Sample records for tail current sheet
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The Topology and Dynamics of Mercury's Tail Plasma and Current Sheets
NASA Astrophysics Data System (ADS)
Al Asad, M. M.; Johnson, C. J.; Philpott, L. C.
2018-05-01
In Mercury's environment, the tail plasma and current sheets represent an integral part of the dynamic magnetosphere. Our study aims to understand the time-averaged, as well as the dynamic, properties of these "sheets" in 3D space using MAG data.
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The Topology and Properties of Mercury's Tail Current Sheet
NASA Astrophysics Data System (ADS)
Al Asad, M.; Johnson, C.; Philpott, L. C.
2017-12-01
The MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft orbited Mercury from March 2011 until April 2015, measuring the vector magnetic field inside and outside the magnetosphere. MESSENGER repeatedly encountered the tail current sheet (TCS) on the nightside of the planet. We examined 1s magnetic field data within 20 minutes of the magnetic equator position on 2435 orbit to characterize the shape and properties of Mercury's TCS and investigate its response to solar wind conditions. Identification of the TCS from vector magnetic field data used the following criteria: (1) a rapid rotation in the field direction from anti-sunward in the southern tail lobe to sunward in the northern lobe, accompanied by (2) a decrease in the field magnitude and (3) an increase in field variability. The current sheet was encountered on 606 orbits allowing the probability of encountering the tail current sheet in the equatorial plane to be mapped. Orbits on which the TCS was identified were binned spatially and superposed epoch analysis used to determine the field magnitude at the edge of the TCS, from which its time-averaged 3D shape was extracted. The TCS has an inner edge at 1.5 RM downtail in the midnight plane with a thickness of 0.34 RM, extends to the observation limit of 2.8 RM, decreasing in thickness to 0.28 RM. The thickness of the TCS increases in the dawn/dusk directions to 0.7 RM at 1.8 RM downtail and ± 1.5 RM from the noon-midnight plane and it warps towards the planet in the dawn/dusk directions. No strong correlations were found between the time-averaged shape and position of the TCS and solar wind conditions such as the solar wind ram pressure and the magnetic disturbance index, nor with parameters that control these conditions such as heliocentric distance. However, it is likely that the TCS does respond to these conditions on time scales too short to be characterized with MESSENGER data. In addition to mapping the shape of the
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NASA Astrophysics Data System (ADS)
Poh, Gangkai; Slavin, James A.; Jia, Xianzhe; Raines, Jim M.; Imber, Suzanne M.; Sun, Wei-Jie; Gershman, Daniel J.; DiBraccio, Gina A.; Genestreti, Kevin J.; Smith, Andy W.
2017-08-01
We analyzed MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) magnetic field and plasma measurements taken during 319 crossings of Mercury's cross-tail current sheet. We found that the measured BZ in the current sheet is higher on the dawnside than the duskside by a factor of ≈3 and the asymmetry decreases with downtail distance. This result is consistent with expectations based upon MHD stress balance. The magnetic fields threading the more stretched current sheet in the duskside have a higher plasma beta than those on the dawnside, where they are less stretched. This asymmetric behavior is confirmed by mean current sheet thickness being greatest on the dawnside. We propose that heavy planetary ion (e.g., Na+) enhancements in the duskside current sheet provides the most likely explanation for the dawn-dusk current sheet asymmetries. We also report the direct measurement of Mercury's substorm current wedge (SCW) formation and estimate the total current due to pileup of magnetic flux to be ≈11 kA. The conductance at the foot of the field lines required to close the SCW current is found to be ≈1.2 S, which is similar to earlier results derived from modeling of Mercury's Region 1 field-aligned currents. Hence, Mercury's regolith is sufficiently conductive for the current to flow radially then across the surface of Mercury's highly conductive iron core. Mercury appears to be closely coupled to its nightside magnetosphere by mass loading of upward flowing heavy planetary ions and electrodynamically by field-aligned currents that transfer momentum and energy to the nightside auroral oval crust and interior. Heavy planetary ion enhancements in Mercury's duskside current sheet provide explanation for cross-tail asymmetries found in this study. The total current due to the pileup of magnetic flux and conductance required to close the SCW current is found to be ≈11 kA and 1.2 S. Mercury is coupled to magnetotail by mass loading of heavy ions
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The Giacobini-Zinner magnetotail - Tail configuration and current sheet
NASA Technical Reports Server (NTRS)
Mccomas, D. J.; Gosling, J. T.; Bame, S. J.; Slavin, J. A.; Smith, E. J.
1987-01-01
The configuration and properties of the draped Giacobini-Zinner magnetotail and its field-reversing current sheet are studied using the combined magnetic field and plasma electron data sets obtained from the International Cometary Explorer spacecraft when it traversed (in October 1985) the comet 7800 km downstream of the nucleus. The MHD equations are used to derive pressure balance and plasma acceleration conditions. The implications of the various properties derived are examined, particularly with regard to the upstream near-nucleus region where the tail formation process occurs.
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NASA Astrophysics Data System (ADS)
Zhao, Duo; Fu, Suiyan; Parks, George K.; Sun, Weijie; Zong, Qiugang; Pan, Dongxiao; Wu, Tong
2017-08-01
We present new observations of electron distributions and the accompanying waves during the current sheet activities at ˜60 RE in the geomagnetic tail detected by the ARTEMIS (Acceleration, Reconnection, Turbulence, and Electrodynamics of the Moon's Interaction with the Sun) spacecraft. We find that electron flat-top distribution is a common feature near the neutral sheet of the tailward flowing plasmas, consistent with the electron distributions that are shaped in the reconnection region. Whistler mode waves are generated by the anisotropic electron temperature associated with the electron flat-top distributions. These whistler mode waves are modulated by low frequency ion scale waves that are possibly excited by the high-energy ions injected during the current sheet instability. The magnetic and electric fields of the ion scale waves are in phase with electron density variations, indicating that they are compressional ion cyclotron waves. Our observations present examples of the dynamical processes occurring during the current sheet activities far downstream of the geomagnetic tail.
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Structure of the Magnetotail Current Sheet
NASA Technical Reports Server (NTRS)
Larson, Douglas J.; Kaufmann, Richard L.
1996-01-01
An orbit tracing technique was used to generate current sheets for three magnetotail models. Groups of ions were followed to calculate the resulting cross-tail current. Several groups then were combined to produce a current sheet. The goal is a model in which the ions and associated electrons carry the electric current distribution needed to generate the magnetic field B in which ion orbits were traced. The region -20 R(sub E) less than x less than - 14 R(sub E) in geocentric solar magnetospheric coordinates was studied. Emphasis was placed on identifying the categories of ion orbits which contribute most to the cross-tail current and on gaining physical insight into the manner by which the ions carry the observed current distribution. Ions that were trapped near z = 0, ions that magnetically mirrored throughout the current sheet, and ions that mirrored near the Earth all were needed. The current sheet structure was determined primarily by ion magnetization currents. Electrons of the observed energies carried relatively little cross-tail current in these quiet time current sheets. Distribution functions were generated and integrated to evaluate fluid parameters. An earlier model in which B depended only on z produced a consistent current sheet, but it did not provide a realistic representation of the Earth's middle magnetotail. In the present study, B changed substantially in the x and z directions but only weakly in the y direction within our region of interest. Plasmas with three characteristic particle energies were used with each of the magnetic field models. A plasma was found for each model in which the density, average energy, cross-tail current, and bulk flow velocity agreed well with satellite observations.
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Structure of the Magnetotail Current Sheet
NASA Technical Reports Server (NTRS)
Larson, Douglas J.; Kaufmann, Richard L.
1996-01-01
An orbit tracing technique was used to generate current sheets for three magnetotail models. Groups of ions were followed to calculate the resulting cross-tail current. Several groups then were combined to produce a current sheet. The goal is a model in which the ions and associated electrons carry the electric current distribution needed to generate the magnetic field B in which ion orbits were traced. The region -20 R(E) less than x less than -14 R(E) in geocentric solar magnetospheric coordinates was studied. Emphasis was placed on identifying the categories of ion orbits which contribute most to the cross-tail current and on gaining physical insight into the manner by which the ions carry the observed current distribution. Ions that were trapped near z = 0, ions that magnetically mirrored throughout the current sheet, and ions that mirrored near the Earth all were needed. The current sheet structure was determined primarily by ion magnetization currents. Electrons of the observed energies carried relatively little cross-tail current in these quiet time current sheets. Distribution functions were generated and integrated to evaluate fluid parameters. An earlier model in which B depended only on z produced a consistent current sheet, but it did not provide a realistic representation of the Earth's middle magnetotail. In the present study, B changed substantially in the x and z directions but only weakly in the y direction within our region of interest. Plasmas with three characteristic particle energies were used with each of the magnetic field models. A plasma was found for each model in which the density, average energy, cross-tail current, and bulk flow velocity agreed well with satellite observations.
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The Jovian magnetotail and its current sheet
NASA Technical Reports Server (NTRS)
Behannon, K. W.; Burlaga, L. F.; Ness, N. F.
1980-01-01
Analyses of Voyager magnetic field measurements have extended the understanding of the structural and temporal characteristics of Jupiter's magnetic tail. The magnitude of the magnetic field in the lobes of the tail is found to decrease with Jovicentric distance approximately as r to he-1.4, compared with the power law exponent of -1.7 found for the rate of decrease along the Pioneer 10 outbound trajectory. Voyager observations of magnetic field component variations with Jovicentric distance in the tail do not support the uniform radial plasma outflow model derived from Pioneer data. Voyager 2 has shown that the azimuthal current sheet which surrounds Jupiter in the inner and middle magnetosphere extends tailward (in the anti-Sun direction) to a distance of at least 100 R sub J. In the tail this current sheet consists of a plasma sheet and embedded neutral sheet. In the region of the tail where the sheet is observed, the variation of the magnetic field as a result of the sheet structure and its 10 hr periodic motion is the dominant variation seen.
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A study of weak anisotropy in electron pressure in the tail current sheet
NASA Technical Reports Server (NTRS)
Lee, D.-Y.; Voigt, G.-H.
1995-01-01
We adopt a magnetotail model with stretched field lines where ion motions are generally nonadiabatic and where it is assumed that the pressure anisotropy resides only in the electron pressure tensor. We show that the magnetic field lines with p(perpendicular) greater than p(parallel) are less stretched than the corresponding field lines in the isotropic model. For p(parallel) greater than p(perpendicular), the magnetic field lines become more and more stretched as the anisotropy approaches the marginal firehose limit, p(parallel) = p(perpendicular) + B(exp 2)/mu(sub 0). We also show that the tail current density is highly enhanced at the firehose limit, a situation that might be subject to a microscopic instability. However, we emphasize that the enhancement in the current density is notable only near the center of the tail current sheet (z = 0). Thus it remains unclear whether any microscopic instability can significantly alter the global magnetic field configuration of the tail. By comparing the radius of the field-line curvature at z = 0 with the particle's gyroradius, we suspect that even the conventional adiabatic description of electrons may become questionable very close to the marginal firehose limit.
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Cross-tail current, field-aligned current, and B(y)
NASA Technical Reports Server (NTRS)
Kaufmann, Richard L.; Lu, Chen; Larson, Douglas J.
1994-01-01
Orbits of individual charged particles were traced in a one-dimensional magnetic field model that included a uniform cross-tail component B(sub yo). The effects of B(sub yo) on the cross-tail current distribution j(sub y)(z), the average cross-tail drift velocity(nu(sub y)z), and the average pitch angle change(delta alpha) experienced during current sheet encounters were calculated. The addition of a B(sub yo) that exceeded several tenths of one nanotesla completely eliminated all resonance effects for odd-N orbits. An odd-N resonance involves ions that enter and exit the current sheet on the same side. Pitch angles of nearly all such ions changed substantially during a typical current sheet interaction, and there was no region of large cross-tail drift velocity in the presence of a modest B(sub yo). the addition of a very large B(sub yo) guide field in the direction that enhances the natural drift produces a large j(y) and small (Delta alpha) for ions with all energies. The addition of a modest B(sub yo) had less effect near even-N resonances. In this case, ions in a small energy range were found to undergo so little change in pitch angle that particles which originated in the ionosphere would pass through the current sheet and return to the conjugate ionosphere. Finally, the cross-tail drift of ions from regions dominated by stochastic orbits to regions dominated by either resonant or guiding center orbits was considered. The ion drift speed changed substantially during such transitions. The accompanying electrons obey the guiding center equations, so electron drift is more uniform. Any difference between gradients in the fluxes associated with electron and ion drifts requires the presence of a Birkeland current in order to maintain charge neutrality. This plasma sheet region therefore serves as a current generator. The analysis predicts that the resulting Birkeland current connects to the lowest altitude equatorial regions in which ions drift to or from a point
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Magnetic configurations of the tilted current sheets in magnetotail
NASA Astrophysics Data System (ADS)
Shen, C.; Rong, Z. J.; Li, X.; Dunlop, M.; Liu, Z. X.; Malova, H. V.; Lucek, E.; Carr, C.
2008-11-01
In this research, the geometrical structures of tilted current sheet and tail flapping waves have been analysed based on multiple spacecraft measurements and some features of the tilted current sheets have been made clear for the first time. The geometrical features of the tilted current sheet revealed in this investigation are as follows: (1) The magnetic field lines (MFLs) in the tilted current sheet are generally plane curves and the osculating planes in which the MFLs lie are about vertical to the equatorial plane, while the normal of the tilted current sheet leans severely to the dawn or dusk side. (2) The tilted current sheet may become very thin, the half thickness of its neutral sheet is generally much less than the minimum radius of the curvature of the MFLs. (3) In the neutral sheet, the field-aligned current density becomes very large and has a maximum value at the center of the current sheet. (4) In some cases, the current density is a bifurcated one, and the two humps of the current density often superpose two peaks in the gradient of magnetic strength, indicating that the magnetic gradient drift current is possibly responsible for the formation of the two humps of the current density in some tilted current sheets. Tilted current sheets often appear along with tail current sheet flapping waves. It is found that, in the tail flapping current sheets, the minimum curvature radius of the MFLs in the current sheet is rather large with values around 1 RE, while the neutral sheet may be very thin, with its half thickness being several tenths of RE. During the flapping waves, the current sheet is tilted substantially, and the maximum tilt angle is generally larger than 45°. The phase velocities of these flapping waves are several tens km/s, while their periods and wavelengths are several tens of minutes, and several earth radii, respectively. These tail flapping events generally last several hours and occur during quiet periods or periods of weak
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Current Sheet Thinning Associated with Dayside Reconnection
NASA Astrophysics Data System (ADS)
Hsieh, M.; Otto, A.; Ma, X.
2011-12-01
The thinning of the near-Earth current sheet during the growth phase is of critical importance to understand geomagnetic substorms and the conditions that lead to the onset of the expansion phase. We have proposed that convection from the midnight tail region to the dayside as the cause for this current sheet thinning. Adiabatic convection from the near-Earth tail region toward the dayside must conserve the entropy on magnetic field lines. This constraint prohibits a source of the magnetic flux from a region further out in the magnetotail. Thus the near-Earth tail region is increasingly depleted of magnetic flux (the Erickson and Wolf [1980] problem) with entropy matching that of flux tubes that are eroded on the dayside. The process is examined by three-dimensional MHD simulations. The properties of the current sheet thinning are determined as a function of the magnitude of convection toward the dayside and the lobe boundary conditions. It is shown that the model yields a time scale, location, and other general characteristics of the current sheet evolution consistent with observations during the substorm growth phase.
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NASA Technical Reports Server (NTRS)
Lyons, L. R.; Speiser, T. W.
1985-01-01
The paper derives an Ohm's law for single-particle motion in a current sheet, where the magnetic field reverses in direction across the sheet. The result is considerably different from the resistive Ohm's law often used in MHD studies of the geomagnetic tail. Single-particle analysis is extended to obtain a self-consistency relation for a current sheet which agrees with previous results. The results are applicable to the concept of reconnection in that the electric field parallel to the current is obtained for a one-dimensional current sheet with constant normal magnetic field. Dissipated energy goes directly into accelerating particles within the current sheet.
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Cross-tail current - Resonant orbits
NASA Technical Reports Server (NTRS)
Kaufmann, Richard L.; Lu, Chen
1993-01-01
A technique to generate self-consistent 1D current sheets is described. Groups of monoenergetic protons were followed in a modified Harris magnetic field. This sample current sheet is characterized by resonant quasi-adiabatic orbits. The magnetic moment of a quasi-adiabatic ion which is injected from outside a current sheet changes substantially during the orbit but returns to almost its initial value by the time the ion leaves. Several ion and electron groups were combined to produce a plasma sheet in which the charged particles carry the currents needed to generate the magnetic field in which the orbits were traced. An electric field also is required to maintain charge neutrality. Three distinct orbit types, one involving untrapped ions and two composed of trapped ions, were identified. Limitations associated with the use of a 1D model also were investigated; it can provide a good physical picture of an important component of the cross-tail current, but cannot adequately describe any region of the magnetotail in which the principal current sheet is separated from the plasma sheet boundary layer by a nearly isotropic outer position of the central plasma sheet.
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Analysis of Magnetic Flux Rope Chains Embedded in Martian Current Sheets Using MAVEN Data
NASA Astrophysics Data System (ADS)
Bowers, C. F.; DiBraccio, G. A.; Brain, D.; Hara, T.; Gruesbeck, J.; Espley, J. R.; Connerney, J. E. P.; Halekas, J. S.
2017-12-01
The magnetotail of Mars is formed as the interplanetary magnetic field (IMF) drapes around the planet's conducting ionosphere and localized crustal magnetic fields. In this scenario, a cross-tail current sheet separates the sunward and anti-sunward tail lobes. This tail current sheet is a highly dynamic region where magnetic reconnection is able to occur between the oppositely oriented fields. Magnetic flux ropes, a by-product of magnetic reconnection in the tail or in the ionosphere characterized by their helical outer wraps and strong axial core field, are commonly observed in the Martian magnetotail. An initial study using Mars Global Surveyor measurements reported a chain of flux ropes in the tail. During this event, 3 flux ropes were observed during a single traversal of the tail current sheet with a duration of 4 minutes. Here, we perform a statistical survey of these chain-of-flux-rope events to characterize their occurrence in the tail current sheet using Mars Atmosphere and Volatile EvolutioN (MAVEN) data. We implement the well-established technique of Minimum Variance Analysis to confirm the helical structure of the flux ropes and also determine local current sheet orientation. Thorough visual examination of more than 1600 orbits has resulted in the identification of 784 tail current sheet traversals. We determine the current sheet thickness to be on the order of 100-1000 km. From these current sheet observations, a subset of 30 events include embedded chain of flux ropes within the current sheet structure. We find that 87% of these flux rope chain events are identified in the southern latitude regions of Mars, associated with crustal fields. Their location suggests that magnetic reconnection occurring near crustal fields may be the source of these flux ropes. These statistical measurements of both current sheets and associated flux rope chains provide information about the complex magnetospheric dynamics at Mars, and how these dynamics affect atmospheric
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Does a Local B-Minimum Appear in the Tail Current Sheet During a Substorm Growth Phase?
NASA Astrophysics Data System (ADS)
Sergeev, V. A.; Gordeev, E. I.; Merkin, V. G.; Sitnov, M. I.
2018-03-01
Magnetic configurations with dBz/dr > 0 in the midtail current sheet are potentially unstable to various instabilities associated with the explosive substorm onset. Their existence is hard to confirm with observations of magnetospheric spacecraft. Here we use remote sensing by low-altitude spacecraft that measured the loss cone filling rate during electron-rich solar particle event, providing information about magnetic properties of the tail current sheet. We found a latitudinally localized anisotropic 30 keV electron loss cone region embedded inside an extended region of isotropic solar electron precipitation. It was persistently observed for more than 0.5 h during isolated growth phase event by six Polar Operational Environmental Satellites spacecraft, which crossed the premidnight auroral oval. The embedded anisotropic region was observed 1° poleward of the outer radiation belt boundary over 4-5 h wide magnetic local time sector, suggesting a persistent ridge-type Bz2/j maximum in the equatorial plasma sheet at distances 15-20 RE. We discuss infrequent observations of such events taking into account recent results of global magnetohydrodynamic simulations.
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Convection Constraints and Current Sheet Thinning During the Substorm Growth Phase
NASA Astrophysics Data System (ADS)
Otto, A.; Hsieh, M.
2012-12-01
A typical property during the growth phase of geomagnetic substorms is the thinning of the near-Earth current sheet, most pronounced in the region between 6 and 15 RE. We propose that the cause for this current sheet thinning is convection from the midnight tail region to the dayside to replenish magnetospheric magnetic flux that is eroded at the dayside as a result of dayside reconnection. Slow (adiabatic) convection from the near-Earth tail region toward the dayside must conserve the entropy on magnetic field lines. This constraint prohibits a source of magnetic flux from a region further out in the magnetotail. Thus the near-Earth tail region is increasingly depleted of magnetic flux (the Erickson and Wolf [1980] problem) with entropy matching that of flux tubes that are eroded on the dayside. It is proposed that the magnetic flux depletion in the near-Earth tail forces the formation of thin current layers. The process is illustrated and examined by three-dimensional meso-scale MHD simulations. It is shown that the simulations yield a time scale, location, and other general characteristics of the current sheet evolution consistent with observations during the substorm growth phase. The developing thin current sheet is easily destabilized and can undergo localized reconnection events. We present properties of the thinning current sheet, the associated entropy evolution, examples of localized reconnection onset and we discuss the dependence of this process on external parameters such the global reconnection rate.
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Dynamic Harris current sheet thickness from Cluster current density and plasma measurements
NASA Technical Reports Server (NTRS)
Thompson, S. M.; Kivelson, M. G.; Khurana, K. K.; McPherron, R. L.; Weygand, J. M.; Balogh, A.; Reme, H.; Kistler, L. M.
2005-01-01
We use the first accurate measurements of current densities in the plasma sheet to calculate the half-thickness and position of the current sheet as a function of time. Our technique assumes a Harris current sheet model, which is parameterized by lobe magnetic field B(o), current sheet half-thickness h, and current sheet position z(sub o). Cluster measurements of magnetic field, current density, and plasma pressure are used to infer the three parameters as a function of time. We find that most long timescale (6-12 hours) current sheet crossings observed by Cluster cannot be described by a static Harris current sheet with a single set of parameters B(sub o), h, and z(sub o). Noting the presence of high-frequency fluctuations that appear to be superimposed on lower frequency variations, we average over running 6-min intervals and use the smoothed data to infer the parameters h(t) and z(sub o)(t), constrained by the pressure balance lobe magnetic field B(sub o)(t). Whereas this approach has been used in previous studies, the spatial gnuhen& now provided by the Cluster magnetometers were unavailable or not well constrained in earlier studies. We place the calculated hdf&cknessa in a magnetospheric context by examining the change in thickness with substorm phase for three case study events and 21 events in a superposed epoch analysis. We find that the inferred half-thickness in many cases reflects the nominal changes experienced by the plasma sheet during substorms (i.e., thinning during growth phase, thickening following substorm onset). We conclude with an analysis of the relative contribution of (Delta)B(sub z)/(Delta)X to the cross-tail current density during substorms. We find that (Delta)B(sub z)/(Delta)X can contribute a significant portion of the cross-tail c m n t around substorm onset.
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Magnetic Configurations of the Tilted Current Sheets and Dynamics of Their Flapping in Magnetotail
NASA Astrophysics Data System (ADS)
Shen, C.; Rong, Z. J.; Li, X.; Dunlop, M.; Liu, Z. X.; Malova, H. V.; Lucek, E.; Carr, C.
2009-04-01
Based on multiple spacecraft measurements, the geometrical structures of tilted current sheet and tail flapping waves have been analyzed and some features of the tilted current sheets have been made clear for the first time. The geometrical features of the tilted current sheet revealed in this investigation are as follows: (1) The magnetic field lines (MFLs) are generally plane curves and the osculating planes in which the MFLs lie are about vertical to the magnetic equatorial plane, while the tilted current sheet may lean severely to the dawn or dusk side. (2) The tilted current sheet may become very thin, its half thickness is generally much less than the minimum radius of the curvature of the MFLs. (3) In the neutral sheet, the field-aligned current density becomes very large and has a maximum value at the center of the current sheet. (4) In some cases, the current density is a bifurcated one, and the two humps of the current density often superpose two peaks in the gradient of magnetic strength, indicating that the magnetic gradient drift current is possibly responsible for the formation of the two humps of the current density in some tilted current sheets. Tilted current sheets often appear along with tail thick current sheet flapping waves. It is found that, in the tail flapping current sheets, the minimum curvature radius of the MFLs in the current sheet is rather large with values around 1RE, while the neutral sheet may be very thin, with its half thickness being several tenths ofRE. During the flapping waves, the current sheet is tilted substantially, and the maximum tilt angle is generally larger than 45
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NASA Technical Reports Server (NTRS)
Slavin, James A.; Boardsen, S. A.; Sarantos, M.; Acuna, M. H.; Anderson, B. J.; Barabash, S.; Benna, M.; Fraenz, M.; Gloeckler, G.; Gold, R. E.;
2008-01-01
At 23:08 UT on 5 June 2007 the MESSENGER spacecraft reached its closest approach altitude (338 km) during its second flyby of Venus en route to its 2011 orbit insertion at Mercury. Whereas no measurements were collected during MESSENGER'S first Venus flyby in October 2006, the Magnetometer (MAG) and the Energetic Particle and Plasma Spectrometer (EPPS) operated successfully throughout this second encounter. Venus provides the solar system's best example to date of a solar wind - ionosphere planetary interaction. We present MESSENGER observations of the near-tail of Venus with emphasis on determining the time scales for magnetic flux transport, the structure of the cross-tail current sheet at very low altitudes (approx. 300 to 1000 km), and the nature and origin of a magnetic flux rope observed in the current sheet. The availability of the simultaneous Venus Express upstream measurements provides a unique opportunity to examine the influence of solar wind plasma and interplanetary magnetic field conditions on this planet's solar wind interaction at solar minimum.
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CURRENT SHEET THINNING AND ENTROPY CONSTRAINTS DURING THE SUBSTORM GROWTH PHASE
NASA Astrophysics Data System (ADS)
Otto, A.; Hall, F., IV
2009-12-01
A typical property during the growth phase of geomagnetic substorms is the thinning of the near-Earth current sheet, most pronounced in the region between 6 and 15 R_E. We propose that the cause for the current sheet thinning is convection from the midnight tail region to the dayside to replenish magnetospheric magnetic flux which is eroded at the dayside as a result of dayside reconnection. Adiabatic convection from the near-Earth tail region toward the dayside must conserve the entropy on magnetic field lines. This constraint prohibits a source of the magnetic flux from a region further out in the magnetotail. Thus the near-Earth tail region is increasingly depleted of magnetic flux (the Erickson and Wolf [1980] problem) with entropy matching that of flux tubes that are eroded on the dayside. It is proposed that the magnetic flux depletion in the near-Earth tail forces the formation of thin current layers. The process is documented by three-dimensional MHD simulations. It is shown that the simulations yield a time scale, location, and other general characteristics of the current sheet evolution during the substorm growth phase.
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2015-01-01
Abstract The basic properties of the near‐Earth current sheet from 8 RE to 12 RE were determined based on Time History of Events and Macroscale Interactions during Substorms (THEMIS) observations from 2007 to 2013. Ampere's law was used to estimate the current density when the locations of two spacecraft were suitable for the calculation. A total of 3838 current density observations were obtained to study the vertical profile. For typical solar wind conditions, the current density near (off) the central plane of the current sheet ranged from 1 to 2 nA/m2 (1 to 8 nA/m2). All the high current densities appeared off the central plane of the current sheet, indicating the formation of a bifurcated current sheet structure when the current density increased above 2 nA/m2. The median profile also showed a bifurcated structure, in which the half thickness was about 3 RE. The distance between the peak of the current density and the central plane of the current sheet was 0.5 to 1 RE. High current densities above 4 nA/m2 were observed in some cases that occurred preferentially during substorms, but they also occurred in quiet times. In contrast to the commonly accepted picture, these high current densities can form without a high solar wind dynamic pressure. In addition, these high current densities can appear in two magnetic configurations: tail‐like and dipolar structures. At least two mechanisms, magnetic flux depletion and new current system formation during the expansion phase, other than plasma sheet compression are responsible for the formation of the bifurcated current sheets. PMID:27722039
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Ring current dynamics and plasma sheet sources. [magnetic storms
NASA Technical Reports Server (NTRS)
Lyons, L. R.
1984-01-01
The source of the energized plasma that forms in geomagnetic storm ring currents, and ring current decay are discussed. The dominant loss processes for ring current ions are identified as charge exchange and resonant interactions with ion-cyclotron waves. Ring current ions are not dominated by protons. At L4 and energies below a few tens of keV, O+ is the most abundant ion, He+ is second, and protons are third. The plasma sheet contributes directly or indirectly to the ring current particle population. An important source of plasma sheet ions is earthward streaming ions on the outer boundary of the plasma sheet. Ion interactions with the current across the geomagnetic tail can account for the formation of this boundary layer. Electron interactions with the current sheet are possibly an important source of plasma sheet electrons.
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NASA Technical Reports Server (NTRS)
Pritchett, P. L.; Coroniti, F. V.
1992-01-01
The firehose marginally stable current sheet, which may model the flow away from the distant reconnection neutral line, assumes that the accelerated particles escape and never return to re-encounter the current region. This assumption fails on the earthward side where the accelerated ions mirror in the geomagnetic dipole field and return to the current sheet at distances up to about 30 R(E) down the tail. Two-dimensional particle simulations are used to demonstrate that the reflected ions drive a 'shock-like' structure in which the incoming flow is decelerated and the Bz field is highly compressed. These effects are similar to those produced by adiabatic choking of steady convection. Possible implications of this interaction for the dynamics of the tail are considered.
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Energized Oxygen : Speiser Current Sheet Bifurcation
NASA Astrophysics Data System (ADS)
George, D. E.; Jahn, J. M.
2017-12-01
A single population of energized Oxygen (O+) is shown to produce a cross-tail bifurcated current sheet in 2.5D PIC simulations of the magnetotail without the influence of magnetic reconnection. Treatment of oxygen in simulations of space plasmas, specifically a magnetotail current sheet, has been limited to thermal energies despite observations of and mechanisms which explain energized ions. We performed simulations of a homogeneous oxygen background, that has been energized in a physically appropriate manner, to study the behavior of current sheets and magnetic reconnection, specifically their bifurcation. This work uses a 2.5D explicit Particle-In-a-Cell (PIC) code to investigate the dynamics of energized heavy ions as they stream Dawn-to-Dusk in the magnetotail current sheet. We present a simulation study dealing with the response of a current sheet system to energized oxygen ions. We establish a, well known and studied, 2-species GEM Challenge Harris current sheet as a starting point. This system is known to eventually evolve and produce magnetic reconnection upon thinning of the current sheet. We added a uniform distribution of thermal O+ to the background. This 3-species system is also known to eventually evolve and produce magnetic reconnection. We add one additional variable to the system by providing an initial duskward velocity to energize the O+. We also traced individual particle motion within the PIC simulation. Three main results are shown. First, energized dawn- dusk streaming ions are clearly seen to exhibit sustained Speiser motion. Second, a single population of heavy ions clearly produces a stable bifurcated current sheet. Third, magnetic reconnection is not required to produce the bifurcated current sheet. Finally a bifurcated current sheet is compatible with the Harris current sheet model. This work is the first step in a series of investigations aimed at studying the effects of energized heavy ions on magnetic reconnection. This work differs
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NASA Technical Reports Server (NTRS)
Baker, D. N.; Mcpherron, R. L.
1990-01-01
A qualitative model of magnetic field reconfiguration as might result from neutral line formation in the central plasma sheet late in a substorm growth phase is considered. It is suggested that magnetic reconnection probably begins before the substorm expansion phase and that cross-tail current is enhanced across the plasma sheet both earthward and tailward of a limited region near the neutral line. Such an enhanced cross-tail current earthward of the original X line region may contribute to thinning the plasma sheet substantially, and this would in turn affect the drift currents in that location, thus enhancing the current even closer toward the earth. In this way a redistribution and progressive diversion of normal cross-tail current throughout much of the inner portion of the plasma sheet could occur. The resulting intensified current, localized at the inner edge of the plasma sheet, would lead to a very thin plasma confinement region. This would explain the very taillike field and extreme particle dropouts often seen late in substorm growth phases.
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The generation of magnetic fields and electric currents in cometary plasma tails
NASA Technical Reports Server (NTRS)
Ip, W.-H.; Mendis, D. A.
1976-01-01
Due to the folding of the interplanetary magnetic field into the tail as a comet sweeps through the interplanetary medium, the magnetic field in the tail can be built up to the order of 100 gammas at a heliocentric distance of about 1 AU. This folding of magnetic flux tubes also results in a cross-tail electric current passing through a neutral sheet. When streams of enhanced plasma density merge with the main tail, cross-tail currents as large as 1 billion A may result. A condition could arise which causes a significant fraction of this current to be discharged through the inner coma, resulting in rapid ionization. The typical time scale for such outbursts of ionization is estimated to be of the order of 10,000 sec, which is in reasonable agreement with observation.
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NASA Technical Reports Server (NTRS)
Baker, D. N.; Mcpherron, R. L.
1990-01-01
A qualitative model of cross-tail current flow is considered. It is suggested that when magnetic reconnection begins, the current effectively flows across the plasma sheet both earthward and tailward of the disruption region near the neutral line. It is shown that an enhanced cross-tail current earthward of this region would thin the plasma sheet substantially due to the magnetic pinch effect. The results explain the very taillike field and extreme particle dropouts often seen late in substorm growth phases.
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A case study of magnetotail current sheet disruption and diversion
NASA Technical Reports Server (NTRS)
Lui, A. T. Y.; Lopez, R. E.; Krimigis, S. M.; Mcentire, R. W.; Zanetti, L. J.
1988-01-01
On June 1, 1985 the AMPTE/CCE spacecraft (at a geocentric distance of about 8.8 earth radii at the midnight neutral sheet region) observed a dispersionless energetic particle injection and an increase in magnetic field magnitude, which are features commonly attributed to disruption of the near-earth cross-tail current sheet during substorm expansion onsets. An analysis based on high time-resolution measurements from the magnetometer and the energetic particle detector indicates that the current sheet disruption region exhibited localized (less than 1 earth radius) and transient (less than 1 min) particle intensity enhancements, accompanied by complex magnetic field changes with occasional development of a southward magnetic field component. Similar features are seen in other current disruption/diversion events observed by the CCE. The present analysis suggests that the current disruption region is quite turbulent, similar to laboratory experiments on current sheet disruption, with signatures unlike those expected from an X-type neutral line configuration. No clear indication of periodicity in any magnetic field parameter is discernible for this current disruption event.
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On the large-scale structure of the tail current as measured by THEMIS
NASA Astrophysics Data System (ADS)
Kalegaev, V. V.; Alexeev, I. I.; Nazarkov, I. S.; Angelopoulos, V.; Runov, A.
2014-11-01
The magnetic field structure and the spatial characteristics of the large-scale currents in the magnetospheric tail were studied during quiet and moderately disturbed geomagnetic conditions in 2009. The magnetic field of the currents other than the tail current was calculated in terms of a paraboloid model of the Earth’s magnetosphere, A2000, and was subtracted from measurements. It was found on the base of obtained tail current magnetic field radial distribution that the inner edge of the tail current sheet is located in the night side magnetosphere, at distances of about 10 RE and of about 7 RE during quiet and disturbed periods respectively. During the disturbance of February 14, 2009 (Dstmin ∼ -35 nT), the Bx and the Bz component of the tail current magnetic field near its inner edge were about 60 nT, and -60 nT that means that strong cross-tail current have been developed. The tail current parameters at different time moments during February 14, 2009 have been estimated. Solar wind conditions during this event were consistent with those during moderate magnetic storms with minimum Dst of about -100 nT. However, the magnetospheric current systems (magnetopause and cross-tail currents) were located at larger geocentric distances than typical during the 2009 extremely quiet epoch and did not provide the expected Dst magnitude. Very small disturbance on the Earth’s surface was detected consistent with an “inflated” magnetosphere.
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Energization of Ions in near-Earth current sheet disruptions
NASA Technical Reports Server (NTRS)
Taktakishvili, A.; Lopez, R. E.; Goodrich, C. C.
1995-01-01
In this study we examine observations made by AMPTE/CCE of energetic ion bursts during seven substorm periods when the satellite was located near the neutral sheet, and CCE observed the disruption cross-tail current in situ. We compare ion observations to analytic calculations of particle acceleration. We find that the acceleration region size, which we assume to be essentially the current disruption region, to be on the order of 1 R(sub E). Events exhibiting weak acceleration had either relatively small acceleration regions (apparently associated with pseudobreakup activity on the ground) or relatively small changes in the local magnetic field (suggesting that the magnitude of the local current disruption region was limited). These results add additional support for the view that the particle bursts observed during turbulent current sheet disruptions are due to inductive acceleration of ions.
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A current disruption mechanism in the neutral sheet - A possible trigger for substorm expansions
NASA Technical Reports Server (NTRS)
Lui, A. T. Y.; Mankofsky, A.; Chang, C.-L.; Papadopoulos, K.; Wu, C. S.
1990-01-01
A linear analysis is performed to investigate the kinetic cross-field streaming instability in the earth's magnetotail neutral sheet region. Numerical solution of the dispersion equation shows that the instability can occur under conditions expected for the neutral sheet just prior to the onset of substorm expansion. The excited waves are obliquely propagating whistlers with a mixed polarization in the lower hybrid frequency range. The ensuing turbulence of this instability can lead to a local reduction of the cross-tail current causing it to continue through the ionosphere to form a substorm current wedge. A substorm expansion onset scenario is proposed based on this instability in which the relative drift between ions and electrons is primarily due to unmagnetized ions undergoing current sheet acceleration in the presence of a cross-tail electric field. The required electric field strength is within the range of electric field values detected in the neutral sheet region during substorm intervals. The skew in local time of substorm onset location and the three conditions under which substorm onset is observed can be understood on the basis of the proposed scenario.
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Impact of the storm-time plasma sheet ion composition on the ring current energy density
NASA Astrophysics Data System (ADS)
Mouikis, C.; Kistler, L. M.; Petrinec, S. M.; Fuselier, S. A.; Cohen, I.
2017-12-01
The adiabatic inward transport of the night-side near-earth ( 6 Re) hot plasma sheet is the dominant contributor to the ring current pressure during storm times. During storm times, the plasma sheet composition in the 6 - 12 Re tail region changes due to O+ entry from the lobes (from the cusp) and the direct feeding from the night side auroral region. In addition, at substorm onset the plasma sheet O+ ions can be preferentially accelerated. We use MMS and observations during two magnetic storms, 5/8/2016 and 7/16/2017, to monitor the composition changes and energization in the 6 - 12 Re plasma sheet region. For both storms the MMS apogee was in the tail. In addition, we use subsequent Van Allen Probe observations (with apogee in the dawn and dusk respectively) to test if the 6-12 Re plasma sheet, observed by MMS, is a sufficient source of the O+ in the ring current. For this we will compare the phase space density (PSD) of the plasma sheet source population and the PSD of the inner magnetosphere at constant magnetic moment values as used in Kistler et al., [2016].
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NASA Astrophysics Data System (ADS)
Wang, C. P.; Xing, X.
2017-12-01
Ultra-Low Frequency (ULF) plasma waves with frequency range between 1 mHz to 10 Hz are widely observed in the Earth's magnetosphere and on the ground. In particular, Pi2 and Pc4 waves have been found to be closely related to many important dynamic processes in the magnetotail, e.g., fast flows (V > 300 km/s). Observations have shown Pi2 waves in association with fast flows in the near-Earth plasma sheet (X>-30 RE). However, in the mid-tail region, where fast flows are more frequently observed than those in the near-Earth magnetotail, this association has not been evaluated. Our preliminary study using ARTEMIS probes in the mid-tail region (X -60 RE) shows close association between Pi2 and Pc4 waves with the presence of fast flows. Strong connection between mid-tail Pi2 pulsations and high-latitude ground Pi2 signatures are also observed. Among many proposed theories for Pi2 wave, ballooning and firehose instabilities are plausible mechanisms in leading to the generation of plasma waves around Pi2 frequency band. Ballooning instability is widely admitted for fast flow associated Pi2 pulsations in the near-Earth region. However, firehose instability is expected to occur more easily in mid-tail and beyond due to the specific pressure anisotropy in that region. We examined the pressure anisotropy conditions and evaluated firehose instability condition for both Pi2 and Pc4 events in mid-tail. It is found that the plasma is unstable against firehose instability in association with the initiation of Pi2 and Pc4 waves. These may suggest that firehose instability can be a wave generation mechanism in the mid-tail region.
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Structure of the Jovian Magnetodisk Current Sheet: Initial Galileo Observations
NASA Technical Reports Server (NTRS)
Russell, C. T.; Huddleston, D. E.; Khurana, K. K.; Kivelson, M. G.
2001-01-01
The ten-degree tilt of the Jovian magnetic dipole causes the magnetic equator to move back and forth across Jupiter's rotational equator and tile Galileo orbit that lies therein. Beyond about 24 Jovian radii, the equatorial current sheet thins and tile magnetic structure changes from quasi-dipolar into magnetodisk-like with two regions of nearly radial but antiparallel magnetic field separated by a strong current layer. The magnetic field at the center of the current sheet is very weak in this region. Herein we examine tile current sheet at radial distances from 24 55 Jovian radii. We find that the magnetic structure very much resembles tile structure seen at planetary magnetopause and tail current sheet crossings. Tile magnetic field variation is mainly linear with little rotation of the field direction, At times there is almost no small-scale structure present and the normal component of the magnetic field is almost constant through the current sheet. At other times there are strong small-scale structures present in both the southward and northward directions. This small-scale structure appears to grow with radial distance and may provide the seeds for tile explosive reconnection observed at even greater radial distances oil tile nightside. Beyond about 40 Jovian radii, the thin current sheet also appears to be almost constantly in oscillatory motion with periods of about 10 min. The amplitude of these oscillations also appears to grow with radial distance. The source of these fluctuations may be dynamical events in tile more distant magnetodisk.
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Ionospheric control of the dawn-dusk asymmetry of the Mars magnetotail current sheet
NASA Astrophysics Data System (ADS)
Liemohn, Michael W.; Xu, Shaosui; Dong, Chuanfei; Bougher, Stephen W.; Johnson, Blake C.; Ilie, Raluca; De Zeeuw, Darren L.
2017-06-01
This study investigates the role of solar EUV intensity at controlling the location of the Mars magnetotail current sheet and the structure of the lobes. Four simulation results are examined from a multifluid magnetohydrodynamic model. The solar wind and interplanetary magnetic field (IMF) conditions are held constant, and the Mars crustal field sources are omitted from the simulation configuration. This isolates the influence of solar EUV. It is found that solar maximum conditions, regardless of season, result in a Venus-like tail configuration with the current sheet shifted to the -Y (dawnside) direction. Solar minimum conditions result in a flipped tail configuration with the current sheet shifted to the +Y (duskside) direction. The lobes follow this pattern, with the current sheet shifting away from the larger lobe with the higher magnetic field magnitude. The physical process responsible for this solar EUV control of the magnetotail is the magnetization of the dayside ionosphere. During solar maximum, the ionosphere is relatively strong and the draped IMF field lines quickly slip past Mars. At solar minimum, the weaker ionosphere allows the draped IMF to move closer to the planet. These lower altitudes of the closest approach of the field line to Mars greatly hinder the day-to-night flow of magnetic flux. This results in a buildup of magnetic flux in the dawnside lobe as the S-shaped topology on that side of the magnetosheath extends farther downtail. The study demonstrates that the Mars dayside ionosphere exerts significant control over the nightside induced magnetosphere of that planet.
Plain Language SummaryMars, which does not have a strong magnetic field, has an induced magnetic environment from the draping of the interplanetary magnetic field from the Sun. It folds around Mars, forming two "lobes" of magnetic field behind the planet with a <span class="hlt">current</span> <span class="hlt">sheet</span> of electrified gas (plasma) behind it. The <span class="hlt">current</span> <span class="hlt">sheet</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMSM51B2468S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMSM51B2468S"><span>Triggering of explosive reconnection in a thick <span class="hlt">current</span> <span class="hlt">sheet</span> via <span class="hlt">current</span> <span class="hlt">sheet</span> compression: Less <span class="hlt">current</span> <span class="hlt">sheet</span> thinning, more temperature anisotropy</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Shimizu, K.; Shinohara, I.; Fujimoto, M.</p> <p>2016-12-01</p> <p>Two-dimensional kinetic simulations of compression of thick <span class="hlt">current</span> <span class="hlt">sheets</span> are performed to see how it can lead to triggering of explosive magnetic reconnection. The <span class="hlt">current</span> <span class="hlt">sheet</span> under study is simply in a Harris-like anti-paralell and symmetric geometry. A one-dimensional pre-study shows that the compression is more effective to make the plasma anisotropy than to thin the <span class="hlt">current</span> <span class="hlt">sheet</span> width. When the lobe magnetic field is amplified by a factor of 2, the plasma temperature anisotropy inside the <span class="hlt">current</span> <span class="hlt">sheet</span> reaches 2 but the <span class="hlt">current</span> <span class="hlt">sheet</span> thickness is reduced only by 1/sqrt(2). If a <span class="hlt">current</span> <span class="hlt">sheet</span> thickness needs to be comparable to the ion inertial scale for reconnection triggering take place, as is widely and frequently mentioned in the research community, the initial thickness cannot be more than a few ion scale for reconnection to set-in. On the other hand, the temperature anisotropy of 2 can be significant for the triggering problem. Two-dimensional simulations show explosive magnetic reconnection to take place even when the initial <span class="hlt">current</span> <span class="hlt">sheet</span> thickness more than an order of magnitude thicker than the ion scale, indicating the resilient triggering drive supplied by the temperature anisotropy. We also discuss how the reconnection triggering capability of the temperature anisotropy boosted tearing mode for thick <span class="hlt">current</span> <span class="hlt">sheets</span> compares with the instabilities in the plane orthogonal to the reconnecting field.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSM13B2380L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSM13B2380L"><span>Intrinsic Dawn-Dusk Asymmetry of Magnetotail Thin <span class="hlt">Current</span> <span class="hlt">Sheet</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lu, S.; Pritchett, P. L.; Angelopoulos, V.; Artemyev, A.</p> <p>2017-12-01</p> <p>Magnetic reconnection and its related phenomena (flux ropes, dipolarization fronts, bursty bulk flows, particle injections, etc.) occur more frequently on the duskside in the Earth's magnetotail. Magnetohydrodynamic simulations attributed the asymmetry to the nonuniform ionospheric conductance through global scale magnetosphere-ionosphere interaction. Hybrid simulations, on the other hand, found an alternative responsible mechanism: the Hall effect in the magnetotail thin <span class="hlt">current</span> <span class="hlt">sheet</span>, but left an open question: What is the physical origin of the asymmetric Hall effect? The answer could be the temperature difference on the two sides and/or the dawn-dusk transportation of magnetic flux and plasmas. In this work, we use 3-D particle-in-cell simulations to further explore the magnetotail dawn-dusk asymmetry. The magnetotail equilibrium contains a dipole magnetic field and a <span class="hlt">current</span> <span class="hlt">sheet</span> region. The simulation is driven by a symmetric and localized (in the y direction) high-latitude electric field, under which the <span class="hlt">current</span> <span class="hlt">sheet</span> thins with a decrease of Bz. During the same time, a dawn-dusk asymmetry is formed intrinsically in the thin <span class="hlt">current</span> <span class="hlt">sheet</span>, with a smaller Bz, a stronger Hall effect (indicated by the Hall electric field Ez), and a stronger cross-<span class="hlt">tail</span> <span class="hlt">current</span> jy on the duskside. The deep origin of the asymmetry is also shown to be dominated by the dawnward E×B drift of magnetic flux and plasmas. A direct consequence of this intrinsic dawn-dusk asymmetry is that it favors magnetotail reconnection and related phenomena to preferentially occur on the duskside.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19910063746&hterms=jump&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Djump','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19910063746&hterms=jump&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Djump"><span>Chaotic jumps in the generalized first adiabatic invariant in <span class="hlt">current</span> <span class="hlt">sheets</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Brittnacher, M. J.; Whipple, E. C.</p> <p>1991-01-01</p> <p>The present study examines how the changes in the generalized first adiabatic invariant J derived from the separatrix crossing theory can be incorporated into the drift variable approach to generating distribution functions. A method is proposed for determining distribution functions for an ensemble of particles following interaction with the <span class="hlt">tail</span> <span class="hlt">current</span> <span class="hlt">sheet</span> by treating the interaction as a scattering problem characterized by changes in the invariant. Generalized drift velocities are obtained for a 1D <span class="hlt">tail</span> configuration by using the generalized first invariant. The invariant remained constant except for the discrete changes caused by chaotic scattering as the particles cross the separatrix.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JGRA..120.1697H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JGRA..120.1697H"><span>Substorm onset: <span class="hlt">Current</span> <span class="hlt">sheet</span> avalanche and stop layer</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Haerendel, Gerhard</p> <p>2015-03-01</p> <p>A new scenario is presented for the onset of a substorm and the nature of the breakup arc. There are two main components, <span class="hlt">current</span> <span class="hlt">sheet</span> avalanche and stop layer. The first refers to an earthward flow of plasma and magnetic flux from the central <span class="hlt">current</span> <span class="hlt">sheet</span> of the <span class="hlt">tail</span>, triggered spontaneously or by some unknown interaction with an auroral streamer or a suddenly appearing eastward flow at the end of the growth phase. The second offers a mechanism to stop the flow abruptly at the interface between magnetosphere and <span class="hlt">tail</span> and extract momentum and energy to be partially processed locally and partially transmitted as Poynting flux toward the ionosphere. The stop layer has a width of the order of the ion inertial length. The different dynamics of the ions entering freely and the magnetized electrons create an electric polarization field which stops the ion flow and drives a Hall <span class="hlt">current</span> by which flow momentum is transferred to the magnetic field. A simple formalism is used to describe the operation of the process and to enable quantitative conclusions. An important conclusion is that by necessity the stop layer is also highly structured in longitude. This offers a natural explanation for the coarse ray structure of the breakup arc as manifestation of elementary paths of energy and momentum transport. The <span class="hlt">currents</span> aligned with the rays are balanced between upward and downward directions. While the avalanche is invoked for explaining the spontaneous substorm onset at the inner edge of the <span class="hlt">tail</span>, the expansion of the breakup arc for many minutes is taken as evidence for a continued formation of new stop layers by arrival of flow bursts from the near-Earth neutral line. This is in line with earlier conclusions about the nature of the breakup arc. Small-scale structure, propagation speed, and energy flux are quantitatively consistent with observations. However, the balanced small-scale <span class="hlt">currents</span> cannot constitute the substorm <span class="hlt">current</span> wedge. The source of the latter must be</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_1");'>1</a></li> <li class="active"><span>2</span></li> <li><a href="#" onclick='return showDiv("page_3");'>3</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_2 --> <div id="page_3" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_1");'>1</a></li> <li><a href="#" onclick='return showDiv("page_2");'>2</a></li> <li class="active"><span>3</span></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="41"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19900008209','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19900008209"><span>A <span class="hlt">current</span> disruption mechanism in the neutral <span class="hlt">sheet</span> for triggering substorm expansions</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Lui, A. T. Y.; Mankofsky, A.; Chang, C.-L.; Papadopoulos, K.; Wu, C. S.</p> <p>1989-01-01</p> <p>Two main areas were addressed in support of an effort to understand mechanism responsible for the broadband electrostatic noise (BEN) observed in the magnetotail. The first area concerns the generation of BEN in the boundary layer region of the magnetotail whereas the second area concerns the occassional presence of BEN in the neutral <span class="hlt">sheet</span> region. For the generation of BEN in the boundary layer region, a hybrid simulation code was developed to perform reliable longtime, quiet, highly resolved simulations of field aligned electron and ion beam flow. The result of the simulation shows that broadband emissions cannot be generated by beam-plasma instability if realistic values of the ion beam parameters are used. The waves generated from beam-plasma instability are highly discrete and are of high frequencies. For the plasma <span class="hlt">sheet</span> boundary layer condition, the wave frequencies are in the kHz range, which is incompatible with the observation that the peak power in BEN occur in the 10's of Hz range. It was found that the BEN characteristics are more consistent with lower hybrid drift instability. For the occasional presence of BEN in the neutral <span class="hlt">sheet</span> region, a linear analysis of the kinetic cross-field streaming instability appropriate to the neutral <span class="hlt">sheet</span> condition just prior to onset of substorm expansion was performed. By solving numerically the dispersion relation, it was found that the instability has a growth time comparable to the onset time scale of substorm onset. The excited waves have a mixed polarization in the lower hybrid frequency range. The imposed drift driving the instability corresponds to unmagnetized ions undergoing <span class="hlt">current</span> <span class="hlt">sheet</span> acceleration in the presence of a cross-<span class="hlt">tail</span> electric field. The required electric field strength is in the 10 mV/m range which is well within the observed electric field values detected in the neutral <span class="hlt">sheet</span> during substorms. This finding can potentially account for the disruption of cross-<span class="hlt">tail</span> <span class="hlt">current</span> and its diversion to</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19900002353','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19900002353"><span>Numerical study of the <span class="hlt">current</span> <span class="hlt">sheet</span> and PSBL in a magnetotail model</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Doxas, I.; Horton, W.; Sandusky, K.; Tajima, T.; Steinolfson, R.</p> <p>1989-01-01</p> <p>The <span class="hlt">current</span> <span class="hlt">sheet</span> and plasma <span class="hlt">sheet</span> boundary layer (PSBL) in a magnetotail model are discussed. A test particle code is used to study the response of ensembles of particles to a two-dimensional, time-dependent model of the geomagnetic <span class="hlt">tail</span>, and test the proposition (Coroniti, 1985a, b; Buchner and Zelenyi, 1986; Chen and Palmadesso, 1986; Martin, 1986) that the stochasticity of the particle orbits in these fields is an important part of the physical mechanism for magnetospheric substorms. The realistic results obtained for the fluid moments of the particle distribution with this simple model, and their insensitivity to initial conditions, is consistent with this hypothesis.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018PPCF...60a4008N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018PPCF...60a4008N"><span>Collisionless <span class="hlt">current</span> <span class="hlt">sheet</span> equilibria</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Neukirch, T.; Wilson, F.; Allanson, O.</p> <p>2018-01-01</p> <p><span class="hlt">Current</span> <span class="hlt">sheets</span> are important for the structure and dynamics of many plasma systems. In space and astrophysical plasmas they play a crucial role in activity processes, for example by facilitating the release of magnetic energy via processes such as magnetic reconnection. In this contribution we will focus on collisionless plasma systems. A sensible first step in any investigation of physical processes involving <span class="hlt">current</span> <span class="hlt">sheets</span> is to find appropriate equilibrium solutions. The theory of collisionless plasma equilibria is well established, but over the past few years there has been a renewed interest in finding equilibrium distribution functions for collisionless <span class="hlt">current</span> <span class="hlt">sheets</span> with particular properties, for example for cases where the <span class="hlt">current</span> density is parallel to the magnetic field (force-free <span class="hlt">current</span> <span class="hlt">sheets</span>). This interest is due to a combination of scientific curiosity and potential applications to space and astrophysical plasmas. In this paper we will give an overview of some of the recent developments, discuss their potential applications and address a number of open questions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015APS..DPPN12101V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015APS..DPPN12101V"><span>Fluctuation dynamics in reconnecting <span class="hlt">current</span> <span class="hlt">sheets</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>von Stechow, Adrian; Grulke, Olaf; Ji, Hantao; Yamada, Masaaki; Klinger, Thomas</p> <p>2015-11-01</p> <p>During magnetic reconnection, a highly localized <span class="hlt">current</span> <span class="hlt">sheet</span> forms at the boundary between opposed magnetic fields. Its steep perpendicular gradients and fast parallel drifts can give rise to a range of instabilities which can contribute to the overall reconnection dynamics. In two complementary laboratory reconnection experiments, MRX (PPPL, Princeton) and VINETA.II (IPP, Greifswald, Germany), magnetic fluctuations are observed within the <span class="hlt">current</span> <span class="hlt">sheet</span>. Despite the large differences in geometries (toroidal vs. linear), plasma parameters (high vs. low beta) and magnetic configuration (low vs. high magnetic guide field), similar broadband fluctuation characteristics are observed in both experiments. These are identified as Whistler-like fluctuations in the lower hybrid frequency range that propagate along the <span class="hlt">current</span> <span class="hlt">sheet</span> in the electron drift direction. They are intrinsic to the localized <span class="hlt">current</span> <span class="hlt">sheet</span> and largely independent of the slower reconnection dynamics. This contribution characterizes these magnetic fluctuations within the wide parameter range accessible by both experiments. Specifically, the fluctuation spectra and wave dispersion are characterized with respect to the magnetic topology and plasma parameters of the reconnecting <span class="hlt">current</span> <span class="hlt">sheet</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19900027062&hterms=marginal&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dmarginal','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19900027062&hterms=marginal&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dmarginal"><span>Collisionless reconnection in a quasi-neutral <span class="hlt">sheet</span> near marginal stability</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Pritchett, P. L.; Coroniti, F. V.; Pellat, R.; Karimabadi, H.</p> <p>1989-01-01</p> <p>Particle simulations are used to investigate the process of collisionless reconnection in a magnetotail configuration which includes a pressure gradient along the <span class="hlt">tail</span> axis and <span class="hlt">tail</span> flaring. In the absence of electron stabilization effects, the tearing mode is stabilized when the ion gyrofrequency in the normal field exceeds the growth rate in the corresponding one-dimensional <span class="hlt">current</span> <span class="hlt">sheet</span>. The presence of a low-frequency electromagnetic perturbation in the lobes can serve to destabilize a marginally stable <span class="hlt">current</span> <span class="hlt">sheet</span> by producing an extended neutral-<span class="hlt">sheet</span> region which can then undergo reconnection. These results help to explain how X-type neutral lines, such as those associated with the onset of magnetospheric substorms, can be formed in the near-earth plasma <span class="hlt">sheet</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..17.1189W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..17.1189W"><span>Flapping <span class="hlt">current</span> <span class="hlt">sheet</span> with superposed waves seen in space and on the ground</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, Guoqiang; Volwerk, Martin; Nakamura, Rumi; Boakes, Peter; Zhang, Tielong; Ge, Yasong; Yoshikawa, Akimasa; Baishev, Dmitry</p> <p>2015-04-01</p> <p>A wavy <span class="hlt">current</span> <span class="hlt">sheet</span> event observed on 15th of October 2004 between 1235 and 1300 UT has been studied by using Cluster and ground-based magnetometer data. Waves propagating from the <span class="hlt">tail</span> centre to the duskside flank with a period ~30 s and wavelength ~1 RE, are superimposed on a flapping <span class="hlt">current</span> <span class="hlt">sheet</span>, accompanied with a bursty bulk flow (BBF). Three Pi2 pulsations, with onset at ~1236, ~1251 and ~1255 UT, respectively, are observed at the Tixie (TIK) station located near the foot-points of Cluster. The mechanism creating the Pi2 (period ~40 s) onset at ~1236 UT is unclear. The second Pi2 (period ~90 s, onset at ~1251 UT) is associated with a strong field-aligned <span class="hlt">current</span>, which has a strong transverse component of the magnetic field, observed by Cluster with a time delay ~60 s. We suggest that it is caused by bouncing Alfvén waves between the northern and southern ionosphere which transport the field-aligned <span class="hlt">current</span>. For the third Pi2 (period ~60 s) there is almost no damping at the first three periods. They occur in conjunction with periodic field-aligned <span class="hlt">currents</span> one-on-one with 72s delay. We suggest that it is generated by these periodic field-aligned <span class="hlt">currents</span>. We conclude that the strong field-aligned <span class="hlt">currents</span> generated in the plasma <span class="hlt">sheet</span> during flapping with superimposed higher frequency waves can drive Pi2 pulsations on the ground, and periodic field-aligned <span class="hlt">currents</span> can even control the period of the Pi2s.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JGRA..11910078W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JGRA..11910078W"><span>Flapping <span class="hlt">current</span> <span class="hlt">sheet</span> with superposed waves seen in space and on the ground</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, G. Q.; Volwerk, M.; Nakamura, R.; Boakes, P.; Zhang, T. L.; Yoshikawa, A.; Baishev, D. G.</p> <p>2014-12-01</p> <p>A wavy <span class="hlt">current</span> <span class="hlt">sheet</span> event observed on 15 October 2004 between 1235 and 1300 UT has been studied by using Cluster and ground-based magnetometer data. Waves propagating from the <span class="hlt">tail</span> center to the duskside flank with a period ~30 s and wavelength ~1 RE are superimposed on a flapping <span class="hlt">current</span> <span class="hlt">sheet</span>, accompanied with a bursty bulk flow. Three Pi2 pulsations, with onset at ~1236, ~1251, and ~1255 UT, respectively, are observed at the Tixie station located near the foot points of Cluster. The mechanism creating the Pi2 (period ~40 s) onset at ~1236 UT is unclear. The second Pi2 (period ~90 s, onset at ~1251 UT) is associated with a strong field-aligned <span class="hlt">current</span>, which has a strong transverse component of the magnetic field, observed by Cluster with a time delay ~60 s. We suggest that it is caused by bouncing Alfvén waves between the northern and southern ionosphere which transport the field-aligned <span class="hlt">current</span>. For the third Pi2 (period ~60 s) there is almost no damping at the first three periods. They occur in conjunction with periodic field-aligned <span class="hlt">currents</span> one-on-one with 72 s delay. We suggest that it is generated by these periodic field-aligned <span class="hlt">currents</span>. We conclude that the strong field-aligned <span class="hlt">currents</span> generated in the plasma <span class="hlt">sheet</span> during flapping with superimposed higher-frequency waves can drive Pi2 pulsations on the ground, and periodic field-aligned <span class="hlt">currents</span> can even control the period of the Pi2s.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19970026617','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19970026617"><span>Penetration of the Interplanetary Magnetic Field B(sub y) into Earth's Plasma <span class="hlt">Sheet</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hau, L.-N.; Erickson, G. M.</p> <p>1995-01-01</p> <p>There has been considerable recent interest in the relationship between the cross-<span class="hlt">tail</span> magnetic field component B(sub y) and <span class="hlt">tail</span> dynamics. The purpose of this paper is to give an overall description of the penetration of the interplanetary magnetic field (IMF) B(sub y) into the near-Earth plasma <span class="hlt">sheet</span>. We show that plasma <span class="hlt">sheet</span> B(sub y) may be generated by the differential shear motion of field lines and enhanced by flux tube compression. The latter mechanism leads to a B(sub y) analogue of the pressure-balance inconsistency as flux tubes move from the far <span class="hlt">tail</span> toward the Earth. The growth of B(sub y), however, may be limited by the dawn-dusk asymmetry in the shear velocity as a result of plasma <span class="hlt">sheet</span> tilting. B(sub y) penetration into the plasma <span class="hlt">sheet</span> implies field-aligned <span class="hlt">currents</span> flowing between hemispheres. These <span class="hlt">currents</span> together with the IMF B(sub y) related mantle field-aligned <span class="hlt">currents</span> effectively shield the lobe from the IMF B(sub y).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19830023295','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19830023295"><span>A comparison of coronal and interplanetary <span class="hlt">current</span> <span class="hlt">sheet</span> inclinations</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Behannon, K. W.; Burlaga, L. F.; Hundhausen, A. J.</p> <p>1983-01-01</p> <p>The HAO white light K-coronameter observations show that the inclination of the heliospheric <span class="hlt">current</span> <span class="hlt">sheet</span> at the base of the corona can be both large (nearly vertical with respect to the solar equator) or small during Cararington rotations 1660 - 1666 and even on a single solar rotation. Voyager 1 and 2 magnetic field observations of crossing of the heliospheric <span class="hlt">current</span> <span class="hlt">sheet</span> at distances from the Sun of 1.4 and 2.8 AU. Two cases are considered, one in which the corresponding coronameter data indicate a nearly vertical (north-south) <span class="hlt">current</span> <span class="hlt">sheet</span> and another in which a nearly horizontal, near equatorial <span class="hlt">current</span> <span class="hlt">sheet</span> is indicated. For the crossings of the vertical <span class="hlt">current</span> <span class="hlt">sheet</span>, a variance analysis based on hour averages of the magnetic field data gave a minimum variance direction consistent with a steep inclination. The horizontal <span class="hlt">current</span> <span class="hlt">sheet</span> was observed by Voyager as a region of mixed polarity and low speeds lasting several days, consistent with multiple crossings of a horizontal but irregular and fluctuating <span class="hlt">current</span> <span class="hlt">sheet</span> at 1.4 AU. However, variance analysis of individual <span class="hlt">current</span> <span class="hlt">sheet</span> crossings in this interval using 1.92 see averages did not give minimum variance directions consistent with a horizontal <span class="hlt">current</span> <span class="hlt">sheet</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015SZF.....1b..49L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015SZF.....1b..49L"><span>On ballooning instability in <span class="hlt">current</span> <span class="hlt">sheets</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Leonovich, Anatoliy; Kozlov, Daniil</p> <p>2015-06-01</p> <p>The problem of instability of the magnetotail <span class="hlt">current</span> <span class="hlt">sheet</span> to azimuthally small-scale Alfvén and slow magnetosonic (SMS) waves is solved. The solutions describe unstable oscillations in the presence of a <span class="hlt">current</span> <span class="hlt">sheet</span> and correspond to the region of stretched closed field lines of the magnetotail. The spectra of eigen-frequencies of several basic harmonics of standing Alfvén and SMS waves are found in the local and WKB approximation, which are compared. It is shown that the oscillation properties obtained in these approximations differ radically. In the local approximation, the Alfvén waves are stable in the entire range of magnetic shells. SMS waves go into the aperiodic instability regime (the regime of the "ballooning" instability), on magnetic shells crossing the <span class="hlt">current</span> <span class="hlt">sheet</span>. In the WKB approximation, both the Alfvén and SMS oscillations go into an unstable regime with a non-zero real part of their eigen-frequency, on magnetic shells crossing the <span class="hlt">current</span> <span class="hlt">sheet</span>. The structure of azimuthally small-scale Alfvén waves across magnetic shells is determined.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22590924-electron-acceleration-magnetic-islands-dynamically-evolved-coronal-current-sheet','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22590924-electron-acceleration-magnetic-islands-dynamically-evolved-coronal-current-sheet"><span>Electron acceleration by magnetic islands in a dynamically evolved coronal <span class="hlt">current</span> <span class="hlt">sheet</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Zhang, Shaohua, E-mail: shzhang@mail.iggcas.ac.cn; Wang, Bin; Meng, Lifei</p> <p>2016-03-25</p> <p>This work simulated the electron acceleration by magnetic islands in a drastically evolved solar coronal <span class="hlt">current</span> <span class="hlt">sheet</span> via the combined 2.5-dimensional (2.5D) resistive Magnetohydrodynamics (MHD) and guiding-center approximation test-particle methods. With high magnetic Reynolds number of 105, the long–thin <span class="hlt">current</span> <span class="hlt">sheet</span> is evolved into a chain of magnetic islands, growing in size and coalescing with each other, due to tearing instability. The acceleration of electrons is studied in one typical phase when several large magnetic islands are formed. The results show that the electrons with an initial Maxwell distribution evolve into a heavy-<span class="hlt">tailed</span> distribution and more than 20% of themore » electrons can be accelerated higher than 200 keV within 0.1 second and some of them can even be energized up to MeV ranges. The most energetic electrons have a tendency to be around the outer regions of the magnetic islands or to be located in the small secondary magnetic islands. We find that the acceleration and spatial distributions of the energetic electrons is caused by the trapping effect of the magnetic islands and the distributions of the parallel electric field E{sub p}.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/1414921-plasmoid-instability-forming-current-sheets','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/1414921-plasmoid-instability-forming-current-sheets"><span>Plasmoid Instability in Forming <span class="hlt">Current</span> <span class="hlt">Sheets</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Comisso, L.; Lingam, M.; Huang, Y. -M.</p> <p></p> <p>The plasmoid instability has revolutionized our understanding of magnetic reconnection in astrophysical environments. By preventing the formation of highly elongated reconnection layers, it is crucial in enabling the rapid energy conversion rates that are characteristic of many astrophysical phenomena. Most previous studies have focused on Sweet–Parker <span class="hlt">current</span> <span class="hlt">sheets</span>, which are unattainable in typical astrophysical systems. Here we derive a general set of scaling laws for the plasmoid instability in resistive and visco-resistive <span class="hlt">current</span> <span class="hlt">sheets</span> that evolve over time. Our method relies on a principle of least time that enables us to determine the properties of the reconnecting <span class="hlt">current</span> <span class="hlt">sheet</span> (aspect ratio and elapsed time) and the plasmoid instability (growth rate, wavenumber, inner layer width) at the end of the linear phase. After this phase the reconnecting <span class="hlt">current</span> <span class="hlt">sheet</span> is disrupted and fast reconnection can occur. The scaling laws of the plasmoid instability are not simple power laws, and they depend on the Lundquist number (S), the magnetic Prandtl number (P m), the noise of the system (more » $${\\psi }_{0}$$), the characteristic rate of <span class="hlt">current</span> <span class="hlt">sheet</span> evolution ($$1/\\tau $$), and the thinning process. We also demonstrate that previous scalings are inapplicable to the vast majority of astrophysical systems. Furthermore, we explore the implications of the new scaling relations in astrophysical systems such as the solar corona and the interstellar medium. In both of these systems, we show that our scaling laws yield values for the growth rate, wavenumber, and aspect ratio that are much smaller than the Sweet–Parker–based scalings.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1414921-plasmoid-instability-forming-current-sheets','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1414921-plasmoid-instability-forming-current-sheets"><span>Plasmoid Instability in Forming <span class="hlt">Current</span> <span class="hlt">Sheets</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Comisso, L.; Lingam, M.; Huang, Y. -M.; ...</p> <p>2017-11-28</p> <p>The plasmoid instability has revolutionized our understanding of magnetic reconnection in astrophysical environments. By preventing the formation of highly elongated reconnection layers, it is crucial in enabling the rapid energy conversion rates that are characteristic of many astrophysical phenomena. Most previous studies have focused on Sweet–Parker <span class="hlt">current</span> <span class="hlt">sheets</span>, which are unattainable in typical astrophysical systems. Here we derive a general set of scaling laws for the plasmoid instability in resistive and visco-resistive <span class="hlt">current</span> <span class="hlt">sheets</span> that evolve over time. Our method relies on a principle of least time that enables us to determine the properties of the reconnecting <span class="hlt">current</span> <span class="hlt">sheet</span> (aspect ratio and elapsed time) and the plasmoid instability (growth rate, wavenumber, inner layer width) at the end of the linear phase. After this phase the reconnecting <span class="hlt">current</span> <span class="hlt">sheet</span> is disrupted and fast reconnection can occur. The scaling laws of the plasmoid instability are not simple power laws, and they depend on the Lundquist number (S), the magnetic Prandtl number (P m), the noise of the system (more » $${\\psi }_{0}$$), the characteristic rate of <span class="hlt">current</span> <span class="hlt">sheet</span> evolution ($$1/\\tau $$), and the thinning process. We also demonstrate that previous scalings are inapplicable to the vast majority of astrophysical systems. Furthermore, we explore the implications of the new scaling relations in astrophysical systems such as the solar corona and the interstellar medium. In both of these systems, we show that our scaling laws yield values for the growth rate, wavenumber, and aspect ratio that are much smaller than the Sweet–Parker–based scalings.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JGRA..122.6049C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JGRA..122.6049C"><span>Planetary period modulations of Saturn's magnetotail <span class="hlt">current</span> <span class="hlt">sheet</span> during northern spring: Observations and modeling</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cowley, S. W. H.; Provan, G.</p> <p>2017-06-01</p> <p>We study Cassini magnetic field observations at Saturn on a sequence of passes through the near-equatorial magnetotail during 2015, focusing on dual modulation of the plasma/<span class="hlt">current</span> <span class="hlt">sheet</span> associated with northern and southern planetary period oscillations (PPOs). Previous study of inner magnetosphere PPOs during this northern spring interval showed that the southern system amplitude was generally half that of the northern during the first part of the year to late August, after which the southern amplitude weakened to less than one-fifth that of the northern. We examine four sequential <span class="hlt">tail</span> passes in the earlier interval, during which prominent PPO-related <span class="hlt">tail</span> field modulations were observed, with relative (beat) phases of the two PPO systems being near in phase, antiphase, and two opposite near-quadrature conditions. We find that the radial field displayed opposite "sawtooth" asymmetry modulations under opposite near-quadrature conditions, related to previous findings under equinoctial conditions with near-equal northern and southern PPO amplitudes, while modulations were near symmetric for in-phase and antiphase conditions, but with larger radial field modulations for in-phase and larger colatitudinal field modulations for antiphase. A simple physical mathematical model of dual modulation is developed, which provides reasonable correspondence with these data using one set of <span class="hlt">current</span> <span class="hlt">sheet</span> parameters while varying only the relative PPO phases, thus demonstrating that dual modulation can be discerned and modeled even when the northern and southern amplitudes differ by a factor of 2. No such effects were consistently discerned during the later interval when the amplitude ratio was >5.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22599868-effects-electron-pressure-anisotropy-current-sheet-configuration','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22599868-effects-electron-pressure-anisotropy-current-sheet-configuration"><span>Effects of electron pressure anisotropy on <span class="hlt">current</span> <span class="hlt">sheet</span> configuration</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Artemyev, A. V., E-mail: aartemyev@igpp.ucla.edu; Angelopoulos, V.; Runov, A.</p> <p>2016-09-15</p> <p>Recent spacecraft observations in the Earth's magnetosphere have demonstrated that the magnetotail <span class="hlt">current</span> <span class="hlt">sheet</span> can be supported by <span class="hlt">currents</span> of anisotropic electron population. Strong electron <span class="hlt">currents</span> are responsible for the formation of very thin (intense) <span class="hlt">current</span> <span class="hlt">sheets</span> playing the crucial role in stability of the Earth's magnetotail. We explore the properties of such thin <span class="hlt">current</span> <span class="hlt">sheets</span> with hot isotropic ions and cold anisotropic electrons. Decoupling of the motions of ions and electrons results in the generation of a polarization electric field. The distribution of the corresponding scalar potential is derived from the electron pressure balance and the quasi-neutrality condition. Wemore » find that electron pressure anisotropy is partially balanced by a field-aligned component of this polarization electric field. We propose a 2D model that describes a thin <span class="hlt">current</span> <span class="hlt">sheet</span> supported by <span class="hlt">currents</span> of anisotropic electrons embedded in an ion-dominated <span class="hlt">current</span> <span class="hlt">sheet</span>. <span class="hlt">Current</span> density profiles in our model agree well with THEMIS observations in the Earth's magnetotail.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23215495','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23215495"><span>Observations of ionospheric electron beams in the plasma <span class="hlt">sheet</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zheng, H; Fu, S Y; Zong, Q G; Pu, Z Y; Wang, Y F; Parks, G K</p> <p>2012-11-16</p> <p>Electrons streaming along the magnetic field direction are frequently observed in the plasma <span class="hlt">sheet</span> of Earth's geomagnetic <span class="hlt">tail</span>. The impact of these field-aligned electrons on the dynamics of the geomagnetic <span class="hlt">tail</span> is however not well understood. Here we report the first detection of field-aligned electrons with fluxes increasing at ~1 keV forming a "cool" beam just prior to the dissipation of energy in the <span class="hlt">current</span> <span class="hlt">sheet</span>. These field-aligned beams at ~15 R(E) in the plasma <span class="hlt">sheet</span> are nearly identical to those commonly observed at auroral altitudes, suggesting the beams are auroral electrons accelerated upward by electric fields parallel (E([parallel])) to the geomagnetic field. The density of the beams relative to the ambient electron density is δn(b)/n(e)~5-13% and the <span class="hlt">current</span> carried by the beams is ~10(-8)-10(-7) A m(-2). These beams in high β plasmas with large density and temperature gradients appear to satisfy the Bohm criteria to initiate <span class="hlt">current</span> driven instabilities.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22654244-dynamical-generation-current-sheets-astrophysical-plasma-turbulence','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22654244-dynamical-generation-current-sheets-astrophysical-plasma-turbulence"><span>THE DYNAMICAL GENERATION OF <span class="hlt">CURRENT</span> <span class="hlt">SHEETS</span> IN ASTROPHYSICAL PLASMA TURBULENCE</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Howes, Gregory G.</p> <p>2016-08-20</p> <p>Turbulence profoundly affects particle transport and plasma heating in many astrophysical plasma environments, from galaxy clusters to the solar corona and solar wind to Earth's magnetosphere. Both fluid and kinetic simulations of plasma turbulence ubiquitously generate coherent structures, in the form of <span class="hlt">current</span> <span class="hlt">sheets</span>, at small scales, and the locations of these <span class="hlt">current</span> <span class="hlt">sheets</span> appear to be associated with enhanced rates of dissipation of the turbulent energy. Therefore, illuminating the origin and nature of these <span class="hlt">current</span> <span class="hlt">sheets</span> is critical to identifying the dominant physical mechanisms of dissipation, a primary aim at the forefront of plasma turbulence research. Here, we presentmore » evidence from nonlinear gyrokinetic simulations that strong nonlinear interactions between counterpropagating Alfvén waves, or strong Alfvén wave collisions, are a natural mechanism for the generation of <span class="hlt">current</span> <span class="hlt">sheets</span> in plasma turbulence. Furthermore, we conceptually explain this <span class="hlt">current</span> <span class="hlt">sheet</span> development in terms of the nonlinear dynamics of Alfvén wave collisions, showing that these <span class="hlt">current</span> <span class="hlt">sheets</span> arise through constructive interference among the initial Alfvén waves and nonlinearly generated modes. The properties of <span class="hlt">current</span> <span class="hlt">sheets</span> generated by strong Alfvén wave collisions are compared to published observations of <span class="hlt">current</span> <span class="hlt">sheets</span> in the Earth's magnetosheath and the solar wind, and the nature of these <span class="hlt">current</span> <span class="hlt">sheets</span> leads to the expectation that Landau damping of the constituent Alfvén waves plays a dominant role in the damping of turbulently generated <span class="hlt">current</span> <span class="hlt">sheets</span>.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSM11A2277E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSM11A2277E"><span>Kinetic Studies of Thin <span class="hlt">Current</span> <span class="hlt">Sheets</span> at Magnetosheath Jets</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Eriksson, E.; Vaivads, A.; Khotyaintsev, Y. V.; Graham, D. B.; Yordanova, E.; Hietala, H.; Markidis, S.; Giles, B. L.; Andre, M.; Russell, C. T.; Le Contel, O.; Burch, J. L.</p> <p>2017-12-01</p> <p>In near-Earth space one of the most turbulent plasma environments is the magnetosheath (MSH) downstream of the quasi-parallel shock. The particle acceleration and plasma thermalization processes there are still not fully understood. Regions of strong localized <span class="hlt">currents</span> are believed to play a key role in those processes. The Magnetospheric Multiscale (MMS) mission has sufficiently high cadence to study these processes in detail. We present details of studies of two different events that contain strong <span class="hlt">current</span> regions inside the MSH downstream of the quasi-parallel shock. In both cases the shape of the <span class="hlt">current</span> region is in the form of a <span class="hlt">sheet</span>, however they show internal 3D structure on the scale of the spacecraft separation (15 and 20 km, respectively). Both <span class="hlt">current</span> <span class="hlt">sheets</span> have a normal magnetic field component different from zero indicating that the regions at the different sides of the <span class="hlt">current</span> <span class="hlt">sheets</span> are magnetically connected. Both <span class="hlt">current</span> <span class="hlt">sheets</span> are boundaries between two different plasma regions. Furthermore, both <span class="hlt">current</span> <span class="hlt">sheets</span> are observed at MSH jets. These jets are characterized by localized dynamic pressure being larger than the solar wind dynamic pressure. One <span class="hlt">current</span> <span class="hlt">sheet</span> does not seem to be reconnecting while the other shows reconnection signatures. Inside the non-reconnecting <span class="hlt">current</span> <span class="hlt">sheet</span> we observe locally accelerated electron beams along the magnetic field. At energies above the beam energy we observe a loss cone consistent with part of the hot MSH-like electrons escaping into the colder solar wind-like plasma. This suggests that the acceleration process within this <span class="hlt">current</span> <span class="hlt">sheet</span> is similar to the one that occurs at the bow shock, where electron beams and loss cones are also observed. Therefore, we conclude that electron beams observed in the MSH do not have to originate from the bow shock, but can also be generated locally inside the MSH. The reconnecting <span class="hlt">current</span> <span class="hlt">sheet</span> also shows signs of thermalization and electron acceleration processes that are</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19950048209&hterms=convection+currents&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dconvection%2Bcurrents','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19950048209&hterms=convection+currents&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dconvection%2Bcurrents"><span>Hybird state of the <span class="hlt">tail</span> mangetic configuration during steady convection events</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Sergeev, V. A.; Pulkkinen, T. I.; Pellinen, T. I.; Tsyganenko, N. A.</p> <p>1994-01-01</p> <p>Previous observations have shown that during periods of steady magnetospheric convection (SMC) a large amount of magnetic flux crosses the plasma <span class="hlt">sheet</span> (corresponding to approximately 10 deg wide auroral oval at the nightside) and that the magnetic configuration in the midtail is relaxed (the curent <span class="hlt">sheet</span> is thick and contains enhanced B(sub Z). These signatures are typical for the substorm recovery phase. Using near-geostationary magnetic field data, magnetic field modeling and a noval diagostic technique (isotropic boundary algorithm), we show that in the near-Earth <span class="hlt">tail</span> the magnetic confirguration is very stretched during the SMC events. This stretching is caused by an intense, thin westward <span class="hlt">current</span>. Because of the srongly depressed B(sub Z), there is a large radial gradient in the near-<span class="hlt">tail</span> magetic field. These signatures have been peviously associated only with the substorm growth phase. Our results indicate that during the SMC periods the magnetic configuration is very peculiar, with co-existing thin near-Earth <span class="hlt">current</span> <span class="hlt">sheet</span> and thick midtail plasma <span class="hlt">sheet</span>. The deep local minimum of the equatorial B(sub Z) that devleops at R approximately 12 R(sub E) is consistent with steady, adiabatic, Earthward convection in the midtail. These results impose contraints on the existing substorm theories, and call for an explanation of how such a stressed configuration can persist for such a long time without <span class="hlt">tail</span> <span class="hlt">current</span> disruptions that occur at the end of a substorm growth phase.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1993A%26A...279..589B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1993A%26A...279..589B"><span><span class="hlt">Current-sheet</span> formation in two-dimensional coronal fields</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Billinghurst, M. N.; Craig, I. J. D.; Sneyd, A. D.</p> <p>1993-11-01</p> <p>The formation of <span class="hlt">current</span> <span class="hlt">sheets</span> by shearing motions in line-tied twin-lobed fields is examined. A general analytic argument shows that <span class="hlt">current</span> <span class="hlt">sheets</span> form along the fieldline bounding the two lobes in the case of both symmetric and asymmetric footpoint motions. In the case of strictly antisymmetric motions however no <span class="hlt">current</span> <span class="hlt">sheets</span> can form. These findings are reinforced by magnetic relaxation experiments involving sheared two-lobed fields represented by Clebsh variables. It is pointed out that, although <span class="hlt">current</span> singularites cannot be expected to form when the line-tying assumption is relaxed, the two-lobed geometry is still consistent with the formation of highly localised <span class="hlt">currents</span> - and strong resistive dissipation - along field lines close to the bounding fieldline.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_1");'>1</a></li> <li><a href="#" onclick='return showDiv("page_2");'>2</a></li> <li class="active"><span>3</span></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_3 --> <div id="page_4" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_2");'>2</a></li> <li><a href="#" onclick='return showDiv("page_3");'>3</a></li> <li class="active"><span>4</span></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="61"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1343562-dynamo-driven-plasmoid-formation-from-current-sheet-instability','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1343562-dynamo-driven-plasmoid-formation-from-current-sheet-instability"><span>Dynamo-driven plasmoid formation from a <span class="hlt">current-sheet</span> instability</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Ebrahimi, F.</p> <p>2016-12-15</p> <p>Axisymmetric <span class="hlt">current</span>-carrying plasmoids are formed in the presence of nonaxisymmetric fluctuations during nonlinear three-dimensional resistive MHD simulations in a global toroidal geometry. In this study, we utilize the helicity injection technique to form an initial poloidal flux in the presence of a toroidal guide field. As helicity is injected, two types of <span class="hlt">current</span> <span class="hlt">sheets</span> are formed from the oppositely directed field lines in the injector region (primary reconnecting <span class="hlt">current</span> <span class="hlt">sheet</span>), and the poloidal flux compression near the plasma edge (edge <span class="hlt">current</span> <span class="hlt">sheet</span>). We first find that nonaxisymmetric fluctuations arising from the <span class="hlt">current-sheet</span> instability isolated near the plasma edge have tearingmore » parity but can nevertheless grow fast (on the poloidal Alfven time scale). These modes saturate by breaking up the <span class="hlt">current</span> <span class="hlt">sheet</span>. Second, for the first time, a dynamo poloidal flux amplification is observed at the reconnection site (in the region of the oppositely directed magnetic field). This fluctuation-induced flux amplification increases the local Lundquist number, which then triggers a plasmoid instability and breaks the primary <span class="hlt">current</span> <span class="hlt">sheet</span> at the reconnection site. Finally, the plasmoids formation driven by large-scale flux amplification, i.e., a large-scale dynamo, observed here has strong implications for astrophysical reconnection as well as fast reconnection events in laboratory plasmas.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1212467-shape-terrestrial-plasma-sheet-near-earth-magnetospheric-tail-imaged-interstellar-boundary-explorer','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1212467-shape-terrestrial-plasma-sheet-near-earth-magnetospheric-tail-imaged-interstellar-boundary-explorer"><span>Shape of the terrestrial plasma <span class="hlt">sheet</span> in the near-Earth magnetospheric <span class="hlt">tail</span> as imaged by the Interstellar Boundary Explorer</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Dayeh, M. A.; Fuselier, S. A.; Funsten, H. O.; ...</p> <p>2015-04-11</p> <p>We present remote, continuous observations from the Interstellar Boundary Explorer of the terrestrial plasma <span class="hlt">sheet</span> location back to -16 Earth radii (R E) in the magnetospheric <span class="hlt">tail</span> using energetic neutral atom emissions. The time period studied includes two orbits near the winter and summer solstices, thus associated with large negative and positive dipole tilt, respectively. Continuous side-view images reveal a complex shape that is dominated mainly by large-scale warping due to the diurnal motion of the dipole axis. Superposed on the global warped geometry are short-time fluctuations in plasma <span class="hlt">sheet</span> location that appear to be consistent with plasma <span class="hlt">sheet</span> flappingmore » and possibly twisting due to changes in the interplanetary conditions. We conclude that the plasma <span class="hlt">sheet</span> warping due to the diurnal motion dominates the average shape of the plasma <span class="hlt">sheet</span>. Over short times, the position of the plasma <span class="hlt">sheet</span> can be dominated by twisting and flapping.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMSH41E..08L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMSH41E..08L"><span><span class="hlt">Current</span> <span class="hlt">Sheet</span> Properties and Dynamics During Sympathetic Breakout Eruptions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lynch, B. J.; Edmondson, J. K.</p> <p>2013-12-01</p> <p>We present the continued analysis of the high-resolution 2.5D MHD simulations of sympathetic magnetic breakout eruptions from a pseudostreamer source region. We examine the generation of X- and O-type null points during the <span class="hlt">current</span> <span class="hlt">sheet</span> tearing and track the magnetic island formation and evolution during periods of reconnection. The magnetic breakout eruption scenario forms an overlying 'breakout' <span class="hlt">current</span> <span class="hlt">sheet</span> that evolves slowly and removes restraining flux from above the sheared field core that will eventually become the center of the erupting flux rope-like structure. The runaway expansion from the expansion-breakout reconnection positive feedback enables the formation of the second, vertical/radial <span class="hlt">current</span> <span class="hlt">sheet</span> underneath the rising sheared field core as in the standard CHSKP eruptive flare scenario. We will examine the flux transfer rates through the breakout and flare <span class="hlt">current</span> <span class="hlt">sheets</span> and compare the properties of the field and plasma inflows into the <span class="hlt">current</span> <span class="hlt">sheets</span> and the reconnection jet outflows into the flare loops and flux rope ejecta.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22599178-continuous-development-current-sheets-near-away-from-magnetic-nulls','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22599178-continuous-development-current-sheets-near-away-from-magnetic-nulls"><span>Continuous development of <span class="hlt">current</span> <span class="hlt">sheets</span> near and away from magnetic nulls</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Kumar, Sanjay; Bhattacharyya, R.</p> <p>2016-04-15</p> <p>The presented computations compare the strength of <span class="hlt">current</span> <span class="hlt">sheets</span> which develop near and away from the magnetic nulls. To ensure the spontaneous generation of <span class="hlt">current</span> <span class="hlt">sheets</span>, the computations are performed congruently with Parker's magnetostatic theorem. The simulations evince <span class="hlt">current</span> <span class="hlt">sheets</span> near two dimensional and three dimensional magnetic nulls as well as away from them. An important finding of this work is in the demonstration of comparative scaling of peak <span class="hlt">current</span> density with numerical resolution, for these different types of <span class="hlt">current</span> <span class="hlt">sheets</span>. The results document <span class="hlt">current</span> <span class="hlt">sheets</span> near two dimensional magnetic nulls to have larger strength while exhibiting a stronger scalingmore » than the <span class="hlt">current</span> <span class="hlt">sheets</span> close to three dimensional magnetic nulls or away from any magnetic null. The comparative scaling points to a scenario where the magnetic topology near a developing <span class="hlt">current</span> <span class="hlt">sheet</span> is important for energetics of the subsequent reconnection.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PhRvE..95b3209K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PhRvE..95b3209K"><span>Criticality and turbulence in a resistive magnetohydrodynamic <span class="hlt">current</span> <span class="hlt">sheet</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Klimas, Alexander J.; Uritsky, Vadim M.</p> <p>2017-02-01</p> <p>Scaling properties of a two-dimensional (2d) plasma physical <span class="hlt">current-sheet</span> simulation model involving a full set of magnetohydrodynamic (MHD) equations with <span class="hlt">current</span>-dependent resistivity are investigated. The <span class="hlt">current</span> <span class="hlt">sheet</span> supports a spatial magnetic field reversal that is forced through loading of magnetic flux containing plasma at boundaries of the simulation domain. A balance is reached between loading and annihilation of the magnetic flux through reconnection at the <span class="hlt">current</span> <span class="hlt">sheet</span>; the transport of magnetic flux from boundaries to <span class="hlt">current</span> <span class="hlt">sheet</span> is realized in the form of spatiotemporal avalanches exhibiting power-law statistics of lifetimes and sizes. We identify this dynamics as self-organized criticality (SOC) by verifying an extended set of scaling laws related to both global and local properties of the <span class="hlt">current</span> <span class="hlt">sheet</span> (critical susceptibility, finite-size scaling of probability distributions, geometric exponents). The critical exponents obtained from this analysis suggest that the model operates in a slowly driven SOC state similar to the mean-field state of the directed stochastic sandpile model. We also investigate multiscale correlations in the velocity field and find them numerically indistinguishable from certain intermittent turbulence (IT) theories. The results provide clues on physical conditions for SOC behavior in a broad class of plasma systems with propagating instabilities, and suggest that SOC and IT may coexist in driven <span class="hlt">current</span> <span class="hlt">sheets</span> which occur ubiquitously in astrophysical and space plasmas.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28297949','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28297949"><span>Criticality and turbulence in a resistive magnetohydrodynamic <span class="hlt">current</span> <span class="hlt">sheet</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Klimas, Alexander J; Uritsky, Vadim M</p> <p>2017-02-01</p> <p>Scaling properties of a two-dimensional (2d) plasma physical <span class="hlt">current-sheet</span> simulation model involving a full set of magnetohydrodynamic (MHD) equations with <span class="hlt">current</span>-dependent resistivity are investigated. The <span class="hlt">current</span> <span class="hlt">sheet</span> supports a spatial magnetic field reversal that is forced through loading of magnetic flux containing plasma at boundaries of the simulation domain. A balance is reached between loading and annihilation of the magnetic flux through reconnection at the <span class="hlt">current</span> <span class="hlt">sheet</span>; the transport of magnetic flux from boundaries to <span class="hlt">current</span> <span class="hlt">sheet</span> is realized in the form of spatiotemporal avalanches exhibiting power-law statistics of lifetimes and sizes. We identify this dynamics as self-organized criticality (SOC) by verifying an extended set of scaling laws related to both global and local properties of the <span class="hlt">current</span> <span class="hlt">sheet</span> (critical susceptibility, finite-size scaling of probability distributions, geometric exponents). The critical exponents obtained from this analysis suggest that the model operates in a slowly driven SOC state similar to the mean-field state of the directed stochastic sandpile model. We also investigate multiscale correlations in the velocity field and find them numerically indistinguishable from certain intermittent turbulence (IT) theories. The results provide clues on physical conditions for SOC behavior in a broad class of plasma systems with propagating instabilities, and suggest that SOC and IT may coexist in driven <span class="hlt">current</span> <span class="hlt">sheets</span> which occur ubiquitously in astrophysical and space plasmas.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSM31A2611A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSM31A2611A"><span>Plasma <span class="hlt">currents</span> and anisotropy in the <span class="hlt">tail</span>-dipole transition region</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Artemyev, A.; Zhang, X. J.; Angelopoulos, V.; Runov, A.</p> <p>2017-12-01</p> <p>Using conjugated THEMIS and Van Allen Probes observations in the nightside magnetosphere, we examine statistically plasma and magnetic field characteristics at multiple locations simultaneously across the 3-10 RE region (i.e., across the <span class="hlt">tail</span>-dipole transition region, whose location depends on <span class="hlt">tail</span> flux loading and the strength of global convection). We find that the spatial distributions of ion and electron anisotropies vary significantly but systematically with radial distance and geomagnetic activity. For low Kp (<2), ions are transversely anisotropic near Earth but isotropic in the <span class="hlt">tail</span>, whereas electrons are isotropic closer to Earth but field-aligned in <span class="hlt">tail</span>. For large Kp (>4), the anisotropy profiles for ions and electrons reverse: ions are isotropic closer to the Earth and field-aligned in the <span class="hlt">tail</span>, whereas electrons are transversely anisotropic closer to Earth but isotropic in the <span class="hlt">tail</span>. Using the measured plasma anisotropy radial profiles we estimate the <span class="hlt">currents</span> from curvature drifts and compare them with diamagnetic <span class="hlt">currents</span>. We also discuss the implications of the observed plasma anisotropies for the presence and spatial distribution of field-aligned electric fields.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1911173L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1911173L"><span>In situ Observations of Heliospheric <span class="hlt">Current</span> <span class="hlt">Sheets</span> Evolution</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Liu, Yong; Peng, Jun; Huang, Jia; Klecker, Berndt</p> <p>2017-04-01</p> <p>We investigate the Heliospheric <span class="hlt">current</span> <span class="hlt">sheet</span> observation time difference of the spacecraft using the STEREO, ACE and WIND data. The observations are first compared to a simple theory in which the time difference is only determined by the radial and longitudinal separation between the spacecraft. The predictions fit well with the observations except for a few events. Then the time delay caused by the latitudinal separation is taken in consideration. The latitude of each spacecraft is calculated based on the PFSS model assuming that heliospheric <span class="hlt">current</span> <span class="hlt">sheets</span> propagate at the solar wind speed without changing their shapes from the origin to spacecraft near 1AU. However, including the latitudinal effects does not improve the prediction, possibly because that the PFSS model may not locate the <span class="hlt">current</span> <span class="hlt">sheets</span> accurately enough. A new latitudinal delay is predicted based on the time delay using the observations on ACE data. The new method improved the prediction on the time lag between spacecraft; however, further study is needed to predict the location of the heliospheric <span class="hlt">current</span> <span class="hlt">sheet</span> more accurately.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19920071979&hterms=disruption&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Ddisruption','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19920071979&hterms=disruption&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Ddisruption"><span>Observational support for the <span class="hlt">current</span> <span class="hlt">sheet</span> catastrophe model of substorm <span class="hlt">current</span> disruption</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Burkhart, G. R.; Lopez, R. E.; Dusenbery, P. B.; Speiser, T. W.</p> <p>1992-01-01</p> <p>The principles of the <span class="hlt">current</span> <span class="hlt">sheet</span> catastrophe models are briefly reviewed, and observations of some of the signatures predicted by the theory are presented. The data considered here include AMPTE/CCE observations of fifteen <span class="hlt">current</span> <span class="hlt">sheet</span> disruption events. According to the model proposed here, the root cause of the <span class="hlt">current</span> disruption is some process, as yet unknown, that leads to an increase in the k sub A parameter. Possible causes for the increase in k sub A are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFMSM51A2278N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFMSM51A2278N"><span>A Description of Local Time Asymmetries in the Kronian <span class="hlt">Current</span> <span class="hlt">Sheet</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nickerson, J. S.; Hansen, K. C.; Gombosi, T. I.</p> <p>2012-12-01</p> <p>Cassini observations imply that Saturn's magnetospheric <span class="hlt">current</span> <span class="hlt">sheet</span> is displaced northward above the rotational equator [C.S. Arridge et al., Warping of Saturn's magnetospheric and magnetotail <span class="hlt">current</span> <span class="hlt">sheets</span>, Journal of Geophysical Research, Vol. 113, August 2008]. Arridge et al. show that this hinging of the <span class="hlt">current</span> <span class="hlt">sheet</span> above the equator occurs over the noon, midnight, and dawn local time sectors. They present an azimuthally independent model to describe this paraboloid-like geometry. We have used our global MHD model, BATS-R-US/SWMF, to study Saturn's magnetospheric <span class="hlt">current</span> <span class="hlt">sheet</span> under various solar wind dynamic pressure and solar zenith angle conditions. We show that under reasonable conditions the <span class="hlt">current</span> <span class="hlt">sheet</span> does take on the basic shape of the Arridge model in the noon, midnight, and dawn sectors. However, the hinging distance parameter used in the Arridge model is not a constant and does in fact vary in Saturn local time. We recommend that the Arridge model should be adjusted to account for this azimuthal dependence. Arridge et al. does not discuss the shape of the <span class="hlt">current</span> <span class="hlt">sheet</span> in the dusk sector due to an absence of data but does presume that the <span class="hlt">current</span> <span class="hlt">sheet</span> will assume the same geometry in this region. On the contrary, our model shows that this is not the case. On the dusk side the <span class="hlt">current</span> <span class="hlt">sheet</span> hinges (aggressively) southward and cannot be accounted for by the Arridge model. We will present results from our simulations showing the deviation from axisymmetry and the general behavior of the <span class="hlt">current</span> <span class="hlt">sheet</span> under different conditions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19920041910&hterms=disruption&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Ddisruption','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19920041910&hterms=disruption&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Ddisruption"><span><span class="hlt">Current</span> disruptions in the near-earth neutral <span class="hlt">sheet</span> region</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Lui, A. T. Y.; Lopez, R. E.; Anderson, B. J.; Takahashi, K.; Zanetti, L. J.; Mcentire, R. W.; Potemra, T. A.; Klumpar, D. M.; Greene, E. M.; Strangeway, R.</p> <p>1992-01-01</p> <p><span class="hlt">Current</span> disruption events observed by the Charge Composition Explorer during 1985 and 1986 are examined. Occurrence of <span class="hlt">current</span> disruption was accompanied by large magnetic field turbulence and frequently with reversal in the sign of the field component normal to the neutral <span class="hlt">sheet</span>. <span class="hlt">Current</span> disruptions in the near-earth region are found to be typically shortlived (about 1-5 min), and their onsets coincide well with the ground onsets of substorm expansion or intensification in the local time sector of the footpoint of the spacecraft. These events are found almost exclusively close to the field reversal plane of the neutral <span class="hlt">sheet</span> (within about 0.5 RE). Prior to <span class="hlt">current</span> disruption the field strength can be reduced to as low as one seventh of the dipole field value and can recover to nearly the dipole value after disruption. The temporal evolution of particle pressure in the near-earth neutral <span class="hlt">sheet</span> during the onset of <span class="hlt">current</span> disruption indicates that the <span class="hlt">current</span> buildup during the substorm growth phase is associated with enhancement in the particle pressure at the neutral <span class="hlt">sheet</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19870011449','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19870011449"><span>Static <span class="hlt">current-sheet</span> models of quiescent prominences</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Wu, F.; Low, B. C.</p> <p>1986-01-01</p> <p>A particular class of theoretical models idealize the prominence to be a discrete flat electric-<span class="hlt">current</span> <span class="hlt">sheet</span> suspended vertically in a potential magnetic field. The weight of the prominence is supported by the Lorentz force in the <span class="hlt">current</span> <span class="hlt">sheet</span>. These models can be extended to have curved electric-<span class="hlt">current</span> <span class="hlt">sheets</span> and to vary three-dimensionally. The equation for force balance is 1 over 4 pi (del times B) times Bdel p- p9 z=zero. Using Cartesian coordinates we take, for simplicity, a uniform gravity with constant acceleration g in the direction -z. If we are interested not in the detailed internal structure of the prominence, but in the global magnetic configuration around the prominence, we may take prominence plasma to be cold. Consideration is given to how such equilibrium states can be constructed. To simplify the mathematical problem, suppose there is no electric <span class="hlt">current</span> in the atmosphere except for the discrete <span class="hlt">currents</span> in the cold prominence <span class="hlt">sheet</span>. Let us take the plane z =0 to be the base of the atmosphere and restrict our attention to the domain z greater than 0. The task we have is to solve for a magnetic field which is everywhere potential except on some free surface S, subject to suit able to boundary conditions. The surface S is determined by requiring that it possesses a discrete electric <span class="hlt">current</span> density such that the Lorentz force on it is everywhere vertically upward to balance the weight of the material m(S). Since the magnetic field is potential in the external atmosphere, the latter is decoupled from the magnetic field and its plane parallel hydrostatic pressure and density can be prescribed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1986NASCP2442...69W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1986NASCP2442...69W"><span>Static <span class="hlt">current-sheet</span> models of quiescent prominences</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wu, F.; Low, B. C.</p> <p>1986-12-01</p> <p>A particular class of theoretical models idealize the prominence to be a discrete flat electric-<span class="hlt">current</span> <span class="hlt">sheet</span> suspended vertically in a potential magnetic field. The weight of the prominence is supported by the Lorentz force in the <span class="hlt">current</span> <span class="hlt">sheet</span>. These models can be extended to have curved electric-<span class="hlt">current</span> <span class="hlt">sheets</span> and to vary three-dimensionally. The equation for force balance is 1 over 4 pi (del times B) times Bdel p- p9 z=zero. Using Cartesian coordinates we take, for simplicity, a uniform gravity with constant acceleration g in the direction -z. If we are interested not in the detailed internal structure of the prominence, but in the global magnetic configuration around the prominence, we may take prominence plasma to be cold. Consideration is given to how such equilibrium states can be constructed. To simplify the mathematical problem, suppose there is no electric <span class="hlt">current</span> in the atmosphere except for the discrete <span class="hlt">currents</span> in the cold prominence <span class="hlt">sheet</span>. Let us take the plane z =0 to be the base of the atmosphere and restrict our attention to the domain z greater than 0. The task we have is to solve for a magnetic field which is everywhere potential except on some free surface S, subject to suit able to boundary conditions. The surface S is determined by requiring that it possesses a discrete electric <span class="hlt">current</span> density such that the Lorentz force on it is everywhere vertically upward to balance the weight of the material m(S). Since the magnetic field is potential in the external atmosphere, the latter is decoupled from the magnetic field and its plane parallel hydrostatic pressure and density can be prescribed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011JGRA..116.9218R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011JGRA..116.9218R"><span>Statistical survey on the magnetic structure in magnetotail <span class="hlt">current</span> <span class="hlt">sheets</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rong, Z. J.; Wan, W. X.; Shen, C.; Li, X.; Dunlop, M. W.; Petrukovich, A. A.; Zhang, T. L.; Lucek, E.</p> <p>2011-09-01</p> <p>On the basis of the multipoint magnetic observations of Cluster in the region 15-19 RE downtail, the magnetic field structure in magnetotail <span class="hlt">current</span> <span class="hlt">sheet</span> (CS) center is statistically surveyed. It is found that the By component (in GSM coordinates) is distributed mainly within ∣By∣ < 5nT, while the Bz component is mostly positive and distributes mainly within 1˜10 nT. The plane of the magnetic field lines (MFLs) is mostly vertical to the equatorial plane, with the radius of curvature (Rc) of the MFLs being directed earthward and the binormal (perpendicular to the curvature and magnetic field direction) being directed azimuthally westward. The curvature radius of MFLs reaches a minimum, Rc,min, at the CS center and is larger than the corresponding local half thickness of the neutral <span class="hlt">sheet</span>, h. Statistically, it is found that the overall surface of the CS, with the normal pointing basically along the south-north direction, can be approximated to be a plane parallel to equatorial plane, although the local CS may be flapping and is frequently tilted to the equatorial plane. The tilted CS (normal inclined to the equatorial plane) is apt to be observed near both flanks and is mainly associated with the slippage of magnetic flux tubes. It is statistically verified that the minimum curvature radius, Rc,min, half thickness of neutral <span class="hlt">sheet</span>, h, and the slipping angle of MFLs, δ, in the CS satisfies h = Rc,min cosδ. The <span class="hlt">current</span> density, with a mean strength of 4-8 nA/m2, basically flows azimuthally and tangentially to the surface of the CS, from dawn side to the dusk side. There is an obvious dawn-dusk asymmetry of CS, however. For magnetic local times (MLT) ˜21:00-˜01:00, the CS is relatively thinner; the minimum curvature radius of MFLs, Rc,min (0.6-1 RE) and the half-thickness of neutral <span class="hlt">sheet</span>, h (0.2-0.4 RE), are relatively smaller, and Bz (3-5 nT) and the minimum magnetic field, Bmin (5-7 nT), are weaker. It is also found that negative Bz has a higher probability</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20030062108','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20030062108"><span>Phenomenological Model of <span class="hlt">Current</span> <span class="hlt">Sheet</span> Canting in Pulsed Electromagnetic Accelerators</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Markusic, Thomas; Choueiri, E. Y.</p> <p>2003-01-01</p> <p>The phenomenon of <span class="hlt">current</span> <span class="hlt">sheet</span> canting in pulsed electromagnetic accelerators is the departure of the plasma <span class="hlt">sheet</span> (that carries the <span class="hlt">current</span>) from a plane that is perpendicular to the electrodes to one that is skewed, or tipped. Review of pulsed electromagnetic accelerator literature reveals that <span class="hlt">current</span> <span class="hlt">sheet</span> canting is a ubiquitous phenomenon - occurring in all of the standard accelerator geometries. Developing an understanding of <span class="hlt">current</span> <span class="hlt">sheet</span> canting is important because it can detract from the propellant sweeping capabilities of <span class="hlt">current</span> <span class="hlt">sheets</span> and, hence, negatively impact the overall efficiency of pulsed electromagnetic accelerators. In the present study, it is postulated that depletion of plasma near the anode, which results from axial density gradient induced diamagnetic drift, occurs during the early stages of the discharge, creating a density gradient normal to the anode, with a characteristic length on the order of the ion skin depth. Rapid penetration of the magnetic field through this region ensues, due to the Hall effect, leading to a canted <span class="hlt">current</span> front ahead of the initial <span class="hlt">current</span> conduction channel. In this model, once the <span class="hlt">current</span> <span class="hlt">sheet</span> reaches appreciable speeds, entrainment of stationary propellant replenishes plasma in the anode region, inhibiting further Hall-convective transport of the magnetic field; however, the previously established tilted <span class="hlt">current</span> <span class="hlt">sheet</span> remains at a fairly constant canting angle for the remainder of the discharge cycle, exerting a transverse J x B force which drives plasma toward the cathode and accumulates it there. This proposed sequence of events has been incorporated into a phenomenological model. The model predicts that canting can be reduced by using low atomic mass propellants with high propellant loading number density; the model results are shown to give qualitative agreement with experimentally measured canting angle mass dependence trends.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSM22B..02N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSM22B..02N"><span>Thin <span class="hlt">current</span> <span class="hlt">sheets</span> observation by MMS during a near-Earth's magnetotail reconnection event</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nakamura, R.; Varsani, A.; Nakamura, T.; Genestreti, K.; Plaschke, F.; Baumjohann, W.; Nagai, T.; Burch, J.; Cohen, I. J.; Ergun, R.; Fuselier, S. A.; Giles, B. L.; Le Contel, O.; Lindqvist, P. A.; Magnes, W.; Schwartz, S. J.; Strangeway, R. J.; Torbert, R. B.</p> <p>2017-12-01</p> <p>During summer 2017, the four spacecraft of the Magnetospheric Multiscale (MMS) mission traversed the nightside magnetotail <span class="hlt">current</span> <span class="hlt">sheet</span> at an apogee of 25 RE. They detected a number of flow reversal events suggestive of the passage of the reconnection <span class="hlt">current</span> <span class="hlt">sheet</span>. Due to the mission's unprecedented high-time resolution and spatial separation well below the ion scales, structure of thin <span class="hlt">current</span> <span class="hlt">sheets</span> is well resolved both with plasma and field measurements. In this study we examine the detailed structure of thin <span class="hlt">current</span> <span class="hlt">sheets</span> during a flow reversal event from tailward flow to Earthward flow, when MMS crossed the center of the <span class="hlt">current</span> <span class="hlt">sheet</span> . We investigate the changes in the structure of the thin <span class="hlt">current</span> <span class="hlt">sheet</span> relative to the X-point based on multi-point analysis. We determine the motion and strength of the <span class="hlt">current</span> <span class="hlt">sheet</span> from curlometer calculations comparing these with <span class="hlt">currents</span> obtained from the particle data. The observed structures of these <span class="hlt">current</span> <span class="hlt">sheets</span> are also compared with simulations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018JGRA..123.2801L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018JGRA..123.2801L"><span>Formation of Dawn-Dusk Asymmetry in Earth's Magnetotail Thin <span class="hlt">Current</span> <span class="hlt">Sheet</span>: A Three-Dimensional Particle-In-Cell Simulation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lu, San; Pritchett, P. L.; Angelopoulos, V.; Artemyev, A. V.</p> <p>2018-04-01</p> <p>Using a three-dimensional particle-in-cell simulation, we investigate the formation of dawn-dusk asymmetry in Earth's magnetotail. The magnetotail <span class="hlt">current</span> <span class="hlt">sheet</span> is compressed by an external driving electric field down to a thickness on the order of ion kinetic scales. In the resultant thin <span class="hlt">current</span> <span class="hlt">sheet</span> (TCS) where the magnetic field line curvature radius is much smaller than ion gyroradius, a significant portion of the ions becomes unmagnetized and decoupled from the magnetized electrons, giving rise to a Hall electric field Ez and an additional cross-<span class="hlt">tail</span> <span class="hlt">current</span> jy caused by the unmagnetized ions being unable to comove with the electrons in the Hall electric field. The Hall electric field transports via E × B drift magnetic flux and magnetized plasma dawnward, causing a reduction of the <span class="hlt">current</span> <span class="hlt">sheet</span> thickness and the normal magnetic field Bz on the duskside. This leads to an even stronger Hall effect (stronger jy and Ez) in the duskside TCS. Thus, due to the internal kinetic effects in the TCS, namely, the Hall effect and the associated dawnward E × B drift, the magnetotail dawn-dusk asymmetry forms in a short time without any global, long-term effects. The duskside preference of reconnection and associated dynamic phenomena (such as substorm onsets, dipolarizing flux bundles, fast flows, energetic particle injections, and flux ropes), which has been pervasively observed by spacecraft in the past 20 years, can thus be explained as a consequence of this TCS asymmetry.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010PhPl...17k2901B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010PhPl...17k2901B"><span>On spontaneous formation of <span class="hlt">current</span> <span class="hlt">sheets</span>: Untwisted magnetic fields</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bhattacharyya, R.; Low, B. C.; Smolarkiewicz, P. K.</p> <p>2010-11-01</p> <p>This is a study of the spontaneous formation of electric <span class="hlt">current</span> <span class="hlt">sheets</span> in an incompressible viscous fluid with perfect electrical conductivity, governed by the magnetohydrodynamic Navier-Stokes equations. Numerical solutions to two initial value problems are presented for a three-dimensional, periodic, untwisted magnetic field evolving, with no change in magnetic topology under the frozen-in condition and at characteristic fluid Reynolds numbers of the order of 500, from a nonequilibrium initial state with the fluid at rest. The evolution converts magnetic free energy into kinetic energy to be all dissipated away by viscosity so that the field settles into a minimum-energy, static equilibrium. The solutions demonstrate that, as a consequence of the frozen-in condition, <span class="hlt">current</span> <span class="hlt">sheets</span> must form during the evolution despite the geometric simplicity of the prescribed initial fields. In addition to the <span class="hlt">current</span> <span class="hlt">sheets</span> associated with magnetic neutral points and field reversal layers, other <span class="hlt">sheets</span> not associated with such magnetic features are also in evidence. These <span class="hlt">current</span> <span class="hlt">sheets</span> form on magnetic flux surfaces. This property is used to achieve a high degree of the frozen-in condition in the simulations, by describing the magnetic field entirely in terms of the advection of its flux surfaces and integrating the resulting governing equations with a customized version of a general-purpose high-resolution (viz., nonoscillatory) hydrodynamical simulation code EULAG [J. M. Prusa et al., Comput. Fluids 37, 1193 (2008)]. Incompressibility imposes the additional global constraint that the flux surfaces must evolve with no change in the spatial volumes they enclose. In this approach, <span class="hlt">current</span> <span class="hlt">sheet</span> formation is demonstrated graphically by the progressive pressing together of suitably selected flux surfaces until their separation has diminished below the minimal resolved distance on a fixed grid. The frozen-in condition then fails in the simulation as the field reconnects through</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22663797-solar-energetic-particle-transport-near-heliospheric-current-sheet','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22663797-solar-energetic-particle-transport-near-heliospheric-current-sheet"><span>Solar Energetic Particle Transport Near a Heliospheric <span class="hlt">Current</span> <span class="hlt">Sheet</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Battarbee, Markus; Dalla, Silvia; Marsh, Mike S., E-mail: mbattarbee@uclan.ac.uk</p> <p>2017-02-10</p> <p>Solar energetic particles (SEPs), a major component of space weather, propagate through the interplanetary medium strongly guided by the interplanetary magnetic field (IMF). In this work, we analyze the implications that a flat Heliospheric <span class="hlt">Current</span> <span class="hlt">Sheet</span> (HCS) has on proton propagation from SEP release sites to the Earth. We simulate proton propagation by integrating fully 3D trajectories near an analytically defined flat <span class="hlt">current</span> <span class="hlt">sheet</span>, collecting comprehensive statistics into histograms, fluence maps, and virtual observer time profiles within an energy range of 1–800 MeV. We show that protons experience significant <span class="hlt">current</span> <span class="hlt">sheet</span> drift to distant longitudes, causing time profiles to exhibitmore » multiple components, which are a potential source of confusing interpretations of observations. We find that variation of the <span class="hlt">current</span> <span class="hlt">sheet</span> thickness within a realistic parameter range has little effect on particle propagation. We show that the IMF configuration strongly affects the deceleration of protons. We show that in our model, the presence of a flat equatorial HCS in the inner heliosphere limits the crossing of protons into the opposite hemisphere.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19740015258','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19740015258"><span>Analysis of Imp-C data from the magnetospheric <span class="hlt">tail</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Speiser, T. W.</p> <p>1973-01-01</p> <p>Satellite magnetic field measurements in the geomagnetic <span class="hlt">tail</span> <span class="hlt">current</span> <span class="hlt">sheet</span> are analyzed to determine the normal field component, and other CS parameters such as thickness, motion, vector <span class="hlt">current</span> density, etc., and to make correlations with auroral activity as measured by the A sub e index. The satellite data used in the initial part of this study were from Explorer 28 and Explorer 34 satellites.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_2");'>2</a></li> <li><a href="#" onclick='return showDiv("page_3");'>3</a></li> <li class="active"><span>4</span></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_4 --> <div id="page_5" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_3");'>3</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li class="active"><span>5</span></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="81"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018Ap%26SS.363...81P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018Ap%26SS.363...81P"><span><span class="hlt">Current</span> and high-β <span class="hlt">sheets</span> in CIR streams: statistics and interaction with the HCS and the magnetosphere</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Potapov, A. S.</p> <p>2018-04-01</p> <p>Thirty events of CIR streams (corotating interaction regions between fast and slow solar wind) were analyzed in order to study statistically plasma structure within the CIR shear zones and to examine the interaction of the CIRs with the heliospheric <span class="hlt">current</span> <span class="hlt">sheet</span> (HCS) and the Earth's magnetosphere. The occurrence of <span class="hlt">current</span> layers and high-beta plasma <span class="hlt">sheets</span> in the CIR structure has been estimated. It was found that on average, each of the CIR streams had four <span class="hlt">current</span> layers in its structure with a <span class="hlt">current</span> density of more than 0.12 A/m2 and about one and a half high-beta plasma regions with a beta value of more than five. Then we traced how and how often the high-speed stream associated with the CIR can catch up with the heliospheric <span class="hlt">current</span> <span class="hlt">sheet</span> (HCS) and connect to it. The interface of each fourth CIR stream coincided in time within an hour with the HCS, but in two thirds of cases, the CIR connection with the HCS was completely absent. One event of the simultaneous observation of the CIR stream in front of the magnetosphere by the ACE satellite in the vicinity of the L1 libration point and the Wind satellite in the remote geomagnetic <span class="hlt">tail</span> was considered in detail. Measurements of the components of the interplanetary magnetic field and plasma parameters showed that the overall structure of the stream is conserved. Moreover, some details of the fine structure are also transferred through the magnetosphere. In particular, the so-called "magnetic hole" almost does not change its shape when moving from L1 point to a neighborhood of L2 point.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19950029339&hterms=Open+Field&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DOpen%2BField','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19950029339&hterms=Open+Field&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DOpen%2BField"><span>A coronal magnetic field model with horizontal volume and <span class="hlt">sheet</span> <span class="hlt">currents</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Zhao, Xuepu; Hoeksema, J. Todd</p> <p>1994-01-01</p> <p>When globally mapping the observed photospheric magnetic field into the corona, the interaction of the solar wind and magnetic field has been treated either by imposing source surface boundary conditions that tacitly require volume <span class="hlt">currents</span> outside the source surface or by limiting the interaction to thin <span class="hlt">current</span> <span class="hlt">sheets</span> between oppositely directed field regions. Yet observations and numerical Magnetohydrodynamic (MHD) calculations suggest the presence of non-force-free volume <span class="hlt">currents</span> throughout the corona as well as thin <span class="hlt">current</span> <span class="hlt">sheets</span> in the neighborhoods of the interfaces between closed and open field lines or between oppositely directed open field lines surrounding coronal helmet-streamer structures. This work presents a model including both horizontal volume <span class="hlt">currents</span> and streamer <span class="hlt">sheet</span> <span class="hlt">currents</span>. The present model builds on the magnetostatic equilibria developed by Bogdan and Low and the <span class="hlt">current-sheet</span> modeling technique developed by Schatten. The calculation uses synoptic charts of the line-of-sight component of the photospheric magnetic field measured at the Wilcox Solar Observatory. Comparison of an MHD model with the calculated model results for the case of a dipole field and comparison of eclipse observations with calculations for CR 1647 (near solar minimum) show that this horizontal <span class="hlt">current-current-sheet</span> model reproduces polar plumes and axes of corona streamers better than the source-surface model and reproduces polar plumes and axes of corona streamers better than the source-surface model and reproduces coro nal helmet structures better than the <span class="hlt">current-sheet</span> model.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19940035204&hterms=balance+sheet&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dbalance%2Bsheet','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19940035204&hterms=balance+sheet&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dbalance%2Bsheet"><span>Self-consistent <span class="hlt">current</span> <span class="hlt">sheet</span> structures in the quiet-time magnetotail</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Holland, Daniel L.; Chen, James</p> <p>1993-01-01</p> <p>The structure of the quiet-time magnetotail is studied using a test particle simulation. Vlasov equilibria are obtained in the regime where v(D) = E(y) c/B(z) is much less than the ion thermal velocity and are self-consistent in that the <span class="hlt">current</span> and magnetic field satisfy Ampere's law. Force balance between the plasma and magnetic field is satisfied everywhere. The global structure of the <span class="hlt">current</span> <span class="hlt">sheet</span> is found to be critically dependent on the source distribution function. The pressure tensor is nondiagonal in the <span class="hlt">current</span> <span class="hlt">sheet</span> with anisotropic temperature. A kinetic mechanism is proposed whereby changes in the source distribution results in a thinning of the <span class="hlt">current</span> <span class="hlt">sheet</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018A%26A...612A..24Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018A%26A...612A..24Z"><span>Pulsar <span class="hlt">current</span> <span class="hlt">sheet</span> C̆erenkov radiation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhang, Fan</p> <p>2018-04-01</p> <p>Plasma-filled pulsar magnetospheres contain thin <span class="hlt">current</span> <span class="hlt">sheets</span> wherein the charged particles are accelerated by magnetic reconnections to travel at ultra-relativistic speeds. On the other hand, the plasma frequency of the more regular force-free regions of the magnetosphere rests almost precisely on the upper limit of radio frequencies, with the cyclotron frequency being far higher due to the strong magnetic field. This combination produces a peculiar situation, whereby radio-frequency waves can travel at subluminal speeds without becoming evanescent. The conditions are thus conducive to C̆erenkov radiation originating from <span class="hlt">current</span> <span class="hlt">sheets</span>, which could plausibly serve as a coherent radio emission mechanism. In this paper we aim to provide a portrait of the relevant processes involved, and show that this mechanism can possibly account for some of the most salient features of the observed radio signals.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017APS..DPPBO6006T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017APS..DPPBO6006T"><span>Tearing Instability of a <span class="hlt">Current</span> <span class="hlt">Sheet</span> Forming by Sheared Incompressible Flow</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tolman, Elizabeth; Loureiro, Nuno; Uzdensky, Dmitri</p> <p>2017-10-01</p> <p>Sweet-Parker <span class="hlt">current</span> <span class="hlt">sheets</span> are unstable to the tearing mode, suggesting they will not form in physical systems. Understanding magnetic reconnection thus requires study of the stability of a <span class="hlt">current</span> <span class="hlt">sheet</span> as it forms. Such formation can occur as a result of sheared, sub-Alfvénic incompressible flows into and along the <span class="hlt">sheet</span>. This work presents an analysis of how tearing perturbations behave in a <span class="hlt">current</span> <span class="hlt">sheet</span> forming under the influence of such flows, beginning with a phase when the growth rate of the tearing mode is small and the behavior of perturbations is primarily governed by ideal MHD. Later, after the tearing growth rate becomes significant relative to the time scale of the driving flows, the flows cause a slight reduction in the tearing growth rate and wave vector of the dominant mode. Once the tearing mode enters the nonlinear regime, the flows accelerate the tearing growth slightly; during X-point collapse, the flows have negligible effect on the system behavior. This analysis allows greater understanding of reconnection in evolving systems and increases confidence in the application of tools developed in time-independent <span class="hlt">current</span> <span class="hlt">sheets</span> to changing <span class="hlt">current</span> <span class="hlt">sheets</span>. This material is based upon work supported by the National Science Foundation Graduate Research Fellowship.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMSM52A..03K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMSM52A..03K"><span>Comparing Sources of Storm-Time Ring <span class="hlt">Current</span> O+</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kistler, L. M.</p> <p>2015-12-01</p> <p>The first observations of the storm-time ring <span class="hlt">current</span> composition using AMPTE/CCE data showed that the O+ contribution to the ring <span class="hlt">current</span> increases significantly during storms. The ring <span class="hlt">current</span> is predominantly formed from inward transport of the near-earth plasma <span class="hlt">sheet</span>. Thus the increase of O+ in the ring <span class="hlt">current</span> implies that the ionospheric contribution to the plasma <span class="hlt">sheet</span> has increased. The ionospheric plasma that reaches the plasma <span class="hlt">sheet</span> can come from both the cusp and the nightside aurora. The cusp outflow moves through the lobe and enters the plasma <span class="hlt">sheet</span> through reconnection at the near-earth neutral line. The nightside auroral outflow has direct access to nightside plasma <span class="hlt">sheet</span>. Using data from Cluster and the Van Allen Probes spacecraft, we compare the development of storms in cases where there is a clear input of nightside auroral outflow, and in cases where there is a significant cusp input. We find that the cusp input, which enters the <span class="hlt">tail</span> at ~15-20 Re becomes isotropized when it crosses the neutral <span class="hlt">sheet</span>, and becomes part of the hot (>1 keV) plasma <span class="hlt">sheet</span> population as it convects inward. The auroral outflow, which enters the plasma <span class="hlt">sheet</span> closer to the earth, where the radius of curvature of the field line is larger, does not isotropize or become significantly energized, but remains a predominantly field aligned low energy population in the inner magnetosphere. It is the hot plasma <span class="hlt">sheet</span> population that gets accelerated to high enough energies in the inner magnetosphere to contribute strongly to the ring <span class="hlt">current</span> pressure. Thus it appears that O+ that enters the plasma <span class="hlt">sheet</span> further down the <span class="hlt">tail</span> has a greater impact on the storm-time ring <span class="hlt">current</span> than ions that enter closer to the earth.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19940025623','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19940025623"><span>Experimental investigation of possible geomagnetic feedback from energetic (0.1 to 16 keV) terrestrial O(+) ions in the magnetotail <span class="hlt">current</span> <span class="hlt">sheet</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Lennartsson, O. W.; Klumpar, D. M.; Shelley, E. G.; Quinn, J. M.</p> <p>1994-01-01</p> <p>Data from energetic ion mass spectrometers on the ISEE 1 and AMPTE/CCE spacecraft are combined with geomagnetic and solar indices to investigate, in a statistical fashion, whether energized O(+) ions of terrestrial origin constitute a source of feedback which triggers or amplifies geomagnetic activity as has been suggested in the literature, by contributing a destabilizing mass increase in the magnetotail <span class="hlt">current</span> <span class="hlt">sheet</span>. The ISEE 1 data (0.1-16 keV/e) provide in situ observations of the O(+) concentration in the central plasma <span class="hlt">sheet</span>, inside of 23 R(sub E), during the rising and maximum phases of solar cycle 21, as well as inner magnetosphere data from same period. The CCE data (0.1-17 keV/e) taken during the subsequent solar minimum all within 9 R(sub E). provide a reference for long-term variations in the magnetosphere O(+) content. Statistical correlations between the ion data and the indices, and between different indices. all point in the same direction: there is probably no feedback specific to the O(+) ions, in spite of the fact that they often contribute most of the ion mass density in the <span class="hlt">tail</span> <span class="hlt">current</span> <span class="hlt">sheet</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003JGRA..108.1168S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003JGRA..108.1168S"><span>Analyses on the geometrical structure of magnetic field in the <span class="hlt">current</span> <span class="hlt">sheet</span> based on cluster measurements</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Shen, C.; Li, X.; Dunlop, M.; Liu, Z. X.; Balogh, A.; Baker, D. N.; Hapgood, M.; Wang, X.</p> <p>2003-05-01</p> <p>The geometrical structure of the magnetic field is a critical character in the magnetospheric dynamics. Using the magnetic field data measured by the Cluster constellation satellites, the geometrical structure including the curvature radius, directions of curvature, and normal of the osculating planes of the magnetic field lines within the <span class="hlt">current</span> <span class="hlt">sheet</span>/neutral <span class="hlt">sheet</span> have been investigated. The results are (1) Inside of the <span class="hlt">tail</span> neutral <span class="hlt">sheet</span> (NS), the curvature of magnetic field lines points towards Earth, the normal of the osculating plane points duskward, and the characteristic half width (or the minimum curvature radius) of the neutral <span class="hlt">sheet</span> is generally less than 2 RE, for many cases less than 1600 km. (2) Outside of the neutral <span class="hlt">sheet</span>, the curvature of magnetic field lines pointed northward (southward) at the north (south) side of NS, the normal of the osculating plane points dawnward, and the curvature radius is about 5 RE ˜ 10 RE. (3) Thin NS, where the magnetic field lines have the minimum of the curvature radius less than 0.25 RE, may appear at all the local time between LT 20 hours and 4 hours, but thin NS occurs more frequently near to midnight than that at the dawnside and duskside. (4) The size of the NS is dependent on substorm phases. Generally, the NS is thin during the growth and expansion phases and grows thick during the recovery phase. (5) For the one-dimensional NS, the half thickness and flapping velocity of the NS could be quantitatively determined. Therefore the differential geometry analyses based on Cluster 4-point magnetic measurements open a window for visioning the three-dimensional static and dynamic magnetic field structure of geomagnetosphere.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19880036617&hterms=Electric+current&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DElectric%2Bcurrent','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19880036617&hterms=Electric+current&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DElectric%2Bcurrent"><span>Spontaneous formation of electric <span class="hlt">current</span> <span class="hlt">sheets</span> and the origin of solar flares</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Low, B. C.; Wolfson, R.</p> <p>1988-01-01</p> <p>It is demonstrated that the continuous boundary motion of a sheared magnetic field in a tenuous plasma with an infinite electrical conductivity can induce the formation of multiple electric <span class="hlt">current</span> <span class="hlt">sheets</span> in the interior plasma. In response to specific footpoint displacements, the quadrupolar magnetic field considered is shown to require the formation of multiple electric <span class="hlt">current</span> <span class="hlt">sheets</span> as it achieves a force-free state. Some of the <span class="hlt">current</span> <span class="hlt">sheets</span> are found to be of finite length, running along separatrix lines of force which separate lobes of magnetic flux. It is suggested that <span class="hlt">current</span> <span class="hlt">sheets</span> in the form of infinitely thin magnetic shear layers may be unstable to resistive tearing, a process which may have application to solar flares.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19950059027&hterms=current+feedback&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dcurrent%2Bfeedback','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19950059027&hterms=current+feedback&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dcurrent%2Bfeedback"><span>Experimental investigation of possible geomagnetic feedback from energetic (0.1 to 16 keV) terrestrial O(+) ions in the magnetotail <span class="hlt">current</span> <span class="hlt">sheet</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Lennartsson, O. W.; Klumpar, D. M.; Shelley, E. G.; Quinn, J. M.</p> <p>1993-01-01</p> <p>Data from energetic ion mass spectrometers on the International Sun Earth Explorer 1 (ISEE 1) and AMPTE/CCE spacecraft are combined with geomagnetic and solar indices to investigate, in a statistical fashion, whether energized O(+) ions of terrestrial origin constitute a source of feedback which triggers or amplifies geomagnetic magnetotail <span class="hlt">current</span> <span class="hlt">sheet</span>. The ISSE 1 data (0.1-16 keV/e) provide in situ observations of the O(+) solar cycle 21, as well as inner magnetosphere data from same period. The CCE data (0.1-17 keV/e), taken during the subsequent solar minimum, all within 9 R(sub E), provide a reference for long-term variations in the magnetosphere O(+) content. Statistical correlations between the ion data and the indices, and between different indices, all point in the same direction: there is probably no feedback specific to the O(+) ions, in spite of the fact that they often contribute most of the ion mass density in the <span class="hlt">tail</span> <span class="hlt">current</span> <span class="hlt">sheet</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004APS..DPPJP1083G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004APS..DPPJP1083G"><span>Spectroscopic Diagnostics of Electric Fields in the Plasma of <span class="hlt">Current</span> <span class="hlt">Sheets</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gavrilenko, Valeri; Kyrie, Natalya P.; Frank, Anna G.; Oks, Eugene</p> <p>2004-11-01</p> <p>Spectroscopic measurements of electric fields (EFs) in <span class="hlt">current</span> <span class="hlt">sheet</span> plasmas were performed in the CS-3D device. The device is intended to study the evolution of <span class="hlt">current</span> <span class="hlt">sheets</span> and the magnetic reconnection phenomena. We used the broadening of spectral lines (SLs) of HeII ions for diagnostics of EFs in the <span class="hlt">current</span> <span class="hlt">sheet</span> middle plane, and the broadening of SLs of HeI atoms for detection of EFs in the <span class="hlt">current</span> <span class="hlt">sheet</span> peripheral regions. For detection of EFs in <span class="hlt">current</span> <span class="hlt">sheet</span> plasma, we used SLs of HeII ions at 468.6; 320.3 and 656.0 nm, as well as SLs of HeI atoms at 667.8; 587.6; 492.2 and 447.1 nm. The latter two lines are of a special interest since their profiles include the dipole-forbidden components along with the allowed components. The experimental data have been analyzed by using the numerical calculations based on the Model Microfield Method. The maximum plasma density in the middle of the <span class="hlt">sheet</span> was in the range (2-8) × 10^16 cm-3, the density in the peripheral regions was (1-2)×10^15 cm-3, and the strength of the quasi-one-dimensional anomalous electric fields in the peripheral regions reached the value of 100 kV/cm. Supported by CRDF, grant RU-P1-2594-MO-04; by the RFBR, grant 03-02-17282; and by the ISTC, project 2098.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19990104373&hterms=masha&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dmasha','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19990104373&hterms=masha&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dmasha"><span>The Onset of Magnetic Reconnection in <span class="hlt">Tail</span>-Like Equilibria</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hesse, Michael; Birn, Joachim; Kuznetsova, Masha</p> <p>1999-01-01</p> <p>Magnetic reconnection is a fundamental mode of dynamics in the magnetotail, and is recognized as the basic mechanisms converting stored magnetic energy into kinetic energy of plasma particles. The effects of the reconnection process are well documented by spacecraft observations of plasmoids in the distant magnetotail, or bursty bulk flows, and magnetic field dipolarizations in the near Earth region. Theoretical and numerical analyses have, in recent years, shed new light on the way reconnection operates, and, in particular, which microscopic mechanism supports the dissipative electric field in the associated diffusion region. Despite this progress, however. the question of how magnetic reconnection initiates in a <span class="hlt">tail</span>-like magnetic field with finite flux threading the <span class="hlt">current</span> i.<span class="hlt">sheet</span> remains unanswered. Instead, theoretical studies supported by numerical simulations support the point-of-view that such plasma and <span class="hlt">current</span> <span class="hlt">sheets</span> are stable with respect to collisionless tearing mode. In this paper, we will further investigate this conclusion, with emphasis on the question whether it remains valid in plasma <span class="hlt">sheets</span> with embedded thin <span class="hlt">current</span> <span class="hlt">sheets</span>. For this purpose, we perform particle-in-cell simulations of the driven formation of thin <span class="hlt">current</span> <span class="hlt">sheets</span>, and their subsequent evolution either to equilibrium or to instability of a tearing-type mode. In the latter case we will pay particular attention to the nature of the electric field contribution which unmagnetizes the electrons.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JNS....27..531M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JNS....27..531M"><span>Nonlinear Dynamics of Non-uniform <span class="hlt">Current</span>-Vortex <span class="hlt">Sheets</span> in Magnetohydrodynamic Flows</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Matsuoka, C.; Nishihara, K.; Sano, T.</p> <p>2017-04-01</p> <p>A theoretical model is proposed to describe fully nonlinear dynamics of interfaces in two-dimensional MHD flows based on an idea of non-uniform <span class="hlt">current</span>-vortex <span class="hlt">sheet</span>. Application of vortex <span class="hlt">sheet</span> model to MHD flows has a crucial difficulty because of non-conservative nature of magnetic tension. However, it is shown that when a magnetic field is initially parallel to an interface, the concept of vortex <span class="hlt">sheet</span> can be extended to MHD flows (<span class="hlt">current</span>-vortex <span class="hlt">sheet</span>). Two-dimensional MHD flows are then described only by a one-dimensional Lagrange parameter on the <span class="hlt">sheet</span>. It is also shown that bulk magnetic field and velocity can be calculated from their values on the <span class="hlt">sheet</span>. The model is tested by MHD Richtmyer-Meshkov instability with sinusoidal vortex <span class="hlt">sheet</span> strength. Two-dimensional ideal MHD simulations show that the nonlinear dynamics of a shocked interface with density stratification agrees fairly well with that for its corresponding potential flow. Numerical solutions of the model reproduce properly the results of the ideal MHD simulations, such as the roll-up of spike, exponential growth of magnetic field, and its saturation and oscillation. Nonlinear evolution of the interface is found to be determined by the Alfvén and Atwood numbers. Some of their dependence on the <span class="hlt">sheet</span> dynamics and magnetic field amplification are discussed. It is shown by the model that the magnetic field amplification occurs locally associated with the nonlinear dynamics of the <span class="hlt">current</span>-vortex <span class="hlt">sheet</span>. We expect that our model can be applicable to a wide variety of MHD shear flows.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19870064427&hterms=GERD&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DGERD','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19870064427&hterms=GERD&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DGERD"><span>The effects of magnetic B(y) component on geomagnetic <span class="hlt">tail</span> equilibria</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hilmer, Robert V.; Voigt, Gerd-Hannes</p> <p>1987-01-01</p> <p>A two-dimensional linear magnetohydrostatic model of the magnetotail is developed here in order to investigate the effects of a significant B(y) component on the configuration of magnetotail equilibria. It is concluded that the enhanced B(y) values must be an essential part of the quiet magnetotail and do not result from a simple intrusion of the IMF. The B(y) field consists of a constant background component plus a nonuniform field existing only in the plasma <span class="hlt">sheet</span>, where it is dependent on the plasma paramater beta and the strength of the magnetic B(z) component. B(y) is strongest at the neutral <span class="hlt">sheet</span> and decreases monotonically in the + or - z direction, reaching a constant <span class="hlt">tail</span> lobe value at the plasma <span class="hlt">sheet</span> boundaries. The presence of a significant positive B(y) component produces <span class="hlt">currents</span>, including field-aligned <span class="hlt">currents</span>, that flow through the equatorial plane and toward and away from earth in the northern and southern halves of the plasma <span class="hlt">sheet</span>, respectively.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22663407-spatial-offsets-flare-cme-current-sheets','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22663407-spatial-offsets-flare-cme-current-sheets"><span>Spatial Offsets in Flare-CME <span class="hlt">Current</span> <span class="hlt">Sheets</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Raymond, John C.; Giordano, Silvio; Ciaravella, Angela, E-mail: jraymond@cfa.harvard.edu</p> <p></p> <p>Magnetic reconnection plays an integral part in nearly all models of solar flares and coronal mass ejections (CMEs). The reconnection heats and accelerates the plasma, produces energetic electrons and ions, and changes the magnetic topology to form magnetic flux ropes and to allow CMEs to escape. Structures that appear between flare loops and CME cores in optical, UV, EUV, and X-ray observations have been identified as <span class="hlt">current</span> <span class="hlt">sheets</span> and have been interpreted in terms of the nature of the reconnection process and the energetics of the events. Many of these studies have used UV spectral observations of high temperature emissionmore » features in the [Fe xviii] and Si xii lines. In this paper, we discuss several surprising cases in which the [Fe xviii] and Si xii emission peaks are spatially offset from each other. We discuss interpretations based on asymmetric reconnection, on a thin reconnection region within a broader streamer-like structure, and on projection effects. Some events seem to be easily interpreted as the projection of a <span class="hlt">sheet</span> that is extended along the line of sight that is viewed an angle, but a physical interpretation in terms of asymmetric reconnection is also plausible. Other events favor an interpretation as a thin <span class="hlt">current</span> <span class="hlt">sheet</span> embedded in a streamer-like structure.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20060016373&hterms=EIT&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DEIT','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20060016373&hterms=EIT&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DEIT"><span><span class="hlt">Current</span> <span class="hlt">Sheet</span> Evolution In The Aftermath Of A CME Event</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Bemporad, A.; Poletto, G.; Seuss, S. T.; Schwardron, N. A.; Elliott, H. A.; Raymond, J. C.</p> <p>2006-01-01</p> <p>We report on SOHO UVCS observations of the coronal restructuring following a coronal mass ejection (CME) on 2002 November 26, at the time of a SOHO-Ulysses quadrature campaign. Starting about 1.5 hr after a CME in the northwest quadrant, UVCS began taking spectra at 1.7 R, covering emission from both cool and hot plasma. Observations continued, with occasional gaps, for more than 2 days. Emission in the 974.8 A line of [Fe XVIII], indicating temperatures above 6 x 10(exp 6) K, was observed throughout the campaign in a spatially limited location. Comparison with EIT images shows the [Fe XVIII] emission to overlie a growing post-flare loop system formed in the aftermath of the CME. The emission most likely originates in a <span class="hlt">current</span> <span class="hlt">sheet</span> overlying the arcade. Analysis of the [Fe XVIII] emission allows us to infer the evolution of physical parameters in the <span class="hlt">current</span> <span class="hlt">sheet</span> over the entire span of our observations: in particular, we give the temperature versus time in the <span class="hlt">current</span> <span class="hlt">sheet</span> and estimate its density. At the time of the quadrature, Ulysses was directly above the location of the CME and intercepted the ejecta. High ionization state Fe was detected by the Ulysses SWICS throughout the magnetic cloud associated with the CME, although its rapid temporal variation suggests bursty, rather than smooth, reconnection in the coronal <span class="hlt">current</span> <span class="hlt">sheet</span>. The SOHO-Ulysses data set provided us with the unique opportunity of analyzing a <span class="hlt">current</span> <span class="hlt">sheet</span> structure from its lowest coronal levels out to its in situ properties. Both the remote and in situ observations are compared with predictions of theoretical CME models.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012APS..DPPCP8049N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012APS..DPPCP8049N"><span>Magnetospheric Reconnection in Modified <span class="hlt">Current-Sheet</span> Equilibria</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Newman, D. L.; Goldman, M. V.; Lapenta, G.; Markidis, S.</p> <p>2012-10-01</p> <p>Particle simulations of magnetic reconnection in Earth's magnetosphere are frequently initialized with a <span class="hlt">current</span>-carrying Harris equilibrium superposed on a <span class="hlt">current</span>-free uniform background plasma. The Harris equilibrium satisfies local charge neutrality, but requires that the <span class="hlt">sheet</span> <span class="hlt">current</span> be dominated by the hotter species -- often the ions in Earth's magnetosphere. This constraint is not necessarily consistent with observations. A modified kinetic equilibrium that relaxes this constraint on the <span class="hlt">currents</span> was proposed by Yamada et al. [Phys. Plasmas., 7, 1781 (2000)] with no background population. These modified equilibria were characterized by an asymptotic converging or diverging electrostatic field normal to the <span class="hlt">current</span> <span class="hlt">sheet</span>. By reintroducing the background plasma, we have developed new families of equilibria where the asymptotic fields are suppressed by Debye shielding. Because the electrostatic potential profiles of these new equilibria contain wells and/or barriers capable of spatially isolating different populations of electrons and/or ions, these solutions can be further generalized to include classes of asymmetric kinetic equilibria. Examples of both symmetric and asymmetric equilibria will be presented. The dynamical evolution of these equilibria, when perturbed, will be further explored by means of implicit 2D PIC reconnection simulations, including comparisons with simulations employing standard Harris-equilibrium initializations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19890064627&hterms=Physics+Motion+Forces&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DPhysics%253A%2BMotion%2BForces','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19890064627&hterms=Physics+Motion+Forces&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DPhysics%253A%2BMotion%2BForces"><span><span class="hlt">Current</span> <span class="hlt">sheet</span> formation in a sheared force-free-magnetic field. [in sun</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Wolfson, Richard</p> <p>1989-01-01</p> <p>This paper presents the results of a study showing how continuous shearing motion of magnetic footpoints in a tenuous, infinitely conducting plasma can lead to the development of <span class="hlt">current</span> <span class="hlt">sheets</span>, despite the absence of such <span class="hlt">sheets</span> or even of neutral points in the initial state. The calculations discussed here verify the earlier suggestion by Low and Wolfson (1988) that extended <span class="hlt">current</span> <span class="hlt">sheets</span> should form due to the shearing of a force-free quadrupolar magnetic field. More generally, this work augments earlier studies suggesting that the appearance of discontinuities - <span class="hlt">current</span> <span class="hlt">sheets</span> - may be a necessary consequence of the topological invariance imposed on the magnetic field geometry of an ideal MHD system by virtue of its infinite conductivity. In the context of solar physics, the work shows how the gradual and continuous motion of magnetic footpoints at the solar photosphere may lead to the buildup of magnetic energy that can then be released explosively when finite conductivity effects become important and lead to the rapid dissipation of <span class="hlt">current</span> <span class="hlt">sheets</span>. Such energy release may be important in solar flares, coronal mass ejections, and other eruptive events.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018MNRAS.476.4263T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018MNRAS.476.4263T"><span>Evolution of three-dimensional relativistic <span class="hlt">current</span> <span class="hlt">sheets</span> and development of self-generated turbulence</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Takamoto, M.</p> <p>2018-05-01</p> <p>In this paper, the temporal evolution of three-dimensional relativistic <span class="hlt">current</span> <span class="hlt">sheets</span> in Poynting-dominated plasma is studied for the first time. Over the past few decades, a lot of efforts have been conducted on studying the evolution of <span class="hlt">current</span> <span class="hlt">sheets</span> in two-dimensional space, and concluded that sufficiently long <span class="hlt">current</span> <span class="hlt">sheets</span> always evolve into the so-called plasmoid chain, which provides a fast reconnection rate independent of its resistivity. However, it is suspected that plasmoid chain can exist only in the case of two-dimensional approximation, and would show transition to turbulence in three-dimensional space. We performed three-dimensional numerical simulation of relativistic <span class="hlt">current</span> <span class="hlt">sheet</span> using resistive relativistic magnetohydrodynamic approximation. The results showed that the three-dimensional <span class="hlt">current</span> <span class="hlt">sheets</span> evolve not into plasmoid chain but turbulence. The resulting reconnection rate is 0.004, which is much smaller than that of plasmoid chain. The energy conversion from magnetic field to kinetic energy of turbulence is just 0.01 per cent, which is much smaller than typical non-relativistic cases. Using the energy principle, we also showed that the plasmoid is always unstable for a displacement in the opposite direction to its acceleration, probably interchange-type instability, and this always results in seeds of turbulence behind the plasmoids. Finally, the temperature distribution along the <span class="hlt">sheet</span> is discussed, and it is found that the <span class="hlt">sheet</span> is less active than plasmoid chain. Our finding can be applied for many high-energy astrophysical phenomena, and can provide a basic model of the general <span class="hlt">current</span> <span class="hlt">sheet</span> in Poynting-dominated plasma.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004APS..DPPBO3011F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004APS..DPPBO3011F"><span>Structure and Dynamics of <span class="hlt">Current</span> <span class="hlt">Sheets</span> in 3D Magnetic Fields with the X-line</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Frank, Anna G.; Bogdanov, S. Yu.; Bugrov, S. G.; Markov, V. S.; Dreiden, G. V.; Ostrovskaya, G. V.</p> <p>2004-11-01</p> <p>Experimental results are presented on the structure of <span class="hlt">current</span> <span class="hlt">sheets</span> formed in 3D magnetic fields with singular lines of the X-type. Two basic diagnostics were used with the device CS - 3D: two-exposure holographic interferometry and magnetic measurements. Formation of extended <span class="hlt">current</span> <span class="hlt">sheets</span> and plasma compression were observed in the presence of the longitudinal magnetic field component aligned with the X-line. Plasma density decreased and the <span class="hlt">sheet</span> thickness increased with an increase of the longitudinal component. We succeeded to reveal formation of the <span class="hlt">sheets</span> taking unusual shape, namely tilted and asymmetric <span class="hlt">sheets</span>, in plasmas with the heavy ions. These <span class="hlt">current</span> <span class="hlt">sheets</span> were obviously different from the planar <span class="hlt">sheets</span> formed in 2D magnetic fields, i.e. without longitudinal component. Analysis of typical plasma parameters made it evident that plasma dynamics and <span class="hlt">current</span> <span class="hlt">sheet</span> evolution should be treated on the base of the two-fluid approach. Specifically it is necessary to take into account the Hall <span class="hlt">currents</span> in the plane perpendicular to the X-line, and the dynamic effects resulting from interaction of the Hall <span class="hlt">currents</span> and the 3D magnetic field. Supported by RFBR, grant 03-02-17282, and ISTC, project 2098.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_3");'>3</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li class="active"><span>5</span></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_5 --> <div id="page_6" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li class="active"><span>6</span></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="101"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSM33B2661P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSM33B2661P"><span>Asymmetry of the Martian <span class="hlt">Current</span> <span class="hlt">Sheet</span> in a Multi-fluid MHD Model</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Panoncillo, S. G.; Egan, H. L.; Dong, C.; Connerney, J. E. P.; Brain, D. A.; Jakosky, B. M.</p> <p>2017-12-01</p> <p>The solar wind carries interplanetary magnetic field (IMF) lines toward Mars, where they drape around the planet's conducting ionosphere, creating a <span class="hlt">current</span> <span class="hlt">sheet</span> behind the planet where the magnetic field has opposite polarity on either side. In its simplest form, the <span class="hlt">current</span> <span class="hlt">sheet</span> is often thought of as symmetric, extending behind the planet along the Mars-Sun line. Observations and model simulations, however, demonstrate that this idealized representation is only an approximation, and the actual scenario is much more complex. The <span class="hlt">current</span> <span class="hlt">sheet</span> can have 3D structure, move back and forth, and be situated dawnward or duskward of the Mars-Sun line. In this project, we utilized a library of global plasma model results for Mars consisting of a collection of multi-fluid MHD simulations where solar max/min, sub-solar longitude, and the orbital position of Mars are varied individually. The model includes Martian crustal fields, and was run for identical steady solar wind conditions. This library was created for the purpose of comparing model results to MAVEN data; we looked at the results of this model library to investigate <span class="hlt">current</span> <span class="hlt">sheet</span> asymmetries. By altering one variable at a time we were able to measure how these variables influence the location of the <span class="hlt">current</span> <span class="hlt">sheet</span>. We found that the <span class="hlt">current</span> <span class="hlt">sheet</span> is typically shifted toward the dusk side of the planet, and that modeled asymmetries are especially prevalent during solar min. Previous model studies that lack crustal fields have found that, for a Parker spiral IMF, the <span class="hlt">current</span> <span class="hlt">sheet</span> will shift dawnward, while our results typically show the opposite. This could expose certain limitations in the models used, or it could reveal an interaction between the solar wind and the plasma environment of Mars that has not yet been explored. MAVEN data may be compared to the model results to confirm the sense of the modeled asymmetry. These results help us to probe the physics controlling the Martian magnetotail and atmospheric</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012CMaPh.311..247C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012CMaPh.311..247C"><span>A priori Estimates for 3D Incompressible <span class="hlt">Current</span>-Vortex <span class="hlt">Sheets</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Coulombel, J.-F.; Morando, A.; Secchi, P.; Trebeschi, P.</p> <p>2012-04-01</p> <p>We consider the free boundary problem for <span class="hlt">current</span>-vortex <span class="hlt">sheets</span> in ideal incompressible magneto-hydrodynamics. It is known that <span class="hlt">current</span>-vortex <span class="hlt">sheets</span> may be at most weakly (neutrally) stable due to the existence of surface waves solutions to the linearized equations. The existence of such waves may yield a loss of derivatives in the energy estimate of the solution with respect to the source terms. However, under a suitable stability condition satisfied at each point of the initial discontinuity and a flatness condition on the initial front, we prove an a priori estimate in Sobolev spaces for smooth solutions with no loss of derivatives. The result of this paper gives some hope for proving the local existence of smooth <span class="hlt">current</span>-vortex <span class="hlt">sheets</span> without resorting to a Nash-Moser iteration. Such result would be a rigorous confirmation of the stabilizing effect of the magnetic field on Kelvin-Helmholtz instabilities, which is well known in astrophysics.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1983GeoRL..10..912B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1983GeoRL..10..912B"><span>Plasma regimes in the deep geomagnetic <span class="hlt">tail</span> - ISEE 3</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bame, S. J.; Anderson, R. C.; Asbridge, J. R.; Baker, D. N.; Feldman, W. C.; Gosling, J. T.; Hones, E. W., Jr.; McComas, D. J.; Zwickl, R. D.</p> <p>1983-09-01</p> <p>The spacecraft remained close to or within a previously unexplored part of the distant (60-220 earth radii) geomagnetic <span class="hlt">tail</span> nearly continuously from January 1 to March 30, 1983. Analysis of the data reveals that all of the plasma regimes identified previously with near-earth measurements (plasma <span class="hlt">sheet</span>, low-latitude boundary layer, plasma mantle, lobe, and magnetosheath) remain recognizable in the distant <span class="hlt">tail</span>. These regimes, however, are found to be intermingled in a more chaotic fashion than near the earth. Within the plasma <span class="hlt">sheet</span> at approximately 200 earth radii, typical flow velocities are about 500 km/s tailward, considerably higher than in the near-earth plasma <span class="hlt">sheet</span>. Earthward flow within the plasma <span class="hlt">sheet</span> is observed occasionally, indicating the temporary presence of a neutral line beyond 220 earth radii. Also found are strong bidirectional electron anisotropies throughout much of the distant plasma <span class="hlt">sheet</span>, boundary layer, and magnetosheath.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20090001288','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20090001288"><span><span class="hlt">Current</span> <span class="hlt">Sheet</span> Formation in a Conical Theta Pinch Faraday Accelerator with Radio-frequency Assisted Discharge</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Polzin, Kurt A.; Hallock, Ashley K.; Choueiri, Edgar Y.</p> <p>2008-01-01</p> <p>Data from an inductive conical theta pinch accelerator are presented to gain insight into the process of inductive <span class="hlt">current</span> <span class="hlt">sheet</span> formation in the presence of a preionized background gas produced by a steady-state RF-discharge. The presence of a preionized plasma has been previously shown to allow for <span class="hlt">current</span> <span class="hlt">sheet</span> formation at lower discharge voltages and energies than those found in other pulsed inductive accelerator concepts, leading to greater accelerator efficiencies at lower power levels. Time-resolved magnetic probe measurements are obtained for different background pressures and pulse energies to characterize the effects of these parameters on <span class="hlt">current</span> <span class="hlt">sheet</span> formation. Indices are defined that describe time-resolved <span class="hlt">current</span> <span class="hlt">sheet</span> characteristics, such as the total <span class="hlt">current</span> owing in the <span class="hlt">current</span> <span class="hlt">sheet</span>, the time-integrated total <span class="hlt">current</span> ('strength'), and <span class="hlt">current</span> <span class="hlt">sheet</span> velocity. It is found that for a given electric field strength, maximums in total <span class="hlt">current</span>, strength, and velocity occur for one particular background pressure. At other pressures, these <span class="hlt">current</span> <span class="hlt">sheet</span> indices are considerably smaller. The trends observed in these indices are explained in terms of the principles behind Townsend breakdown that lead to a dependence on the ratio of the electric field to the background pressure. Time-integrated photographic data are also obtained at the same experimental conditions, and qualitatively they compare quite favorably with the time-resolved magnetic field data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20050207500&hterms=EIT&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DEIT','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20050207500&hterms=EIT&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DEIT"><span>Coronal <span class="hlt">Current</span> <span class="hlt">Sheet</span> Evolution in the Aftermath of a CME</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Bemporad, A.; Poletto, G.; Suess, S. T.; Ko, Y.-K.; Schwadron, N. A.; Elliott, H. A.; Raymond, J. C.</p> <p>2005-01-01</p> <p>We report on SOHO-UVCS observations of coronal restructuring following a Coronal Mass Ejection (CME) on November 26, 2002, at the time of a SOHO-Ulysses quadrature campaign. Starting about 3 hours after the CME, which was directed towards Ulysses, UVCS began taking spectra at 1.7 solar radii, covering emission from both cool and hot plasma. Observations continued, with occasional gaps, for more than 2 days. Emission in the 974.8 Angstrom line of [Fe XVIII], indicating temperatures above 6x10(6) K, was observed throughout the campaign in a spatially limited location. Comparison with EIT images shows the [Fe XVIII] emission to overlie a growing post-flare loop system formed in the aftermath of the CME. The emission most likely originates in a <span class="hlt">current</span> <span class="hlt">sheet</span> overlying the arcade. Analysis of the [Fe XVIII] emission allows us to infer the evolution of physical parameters in the <span class="hlt">current</span> <span class="hlt">sheet</span> over the entire span of our observations: in particular, we give the temperature vs. time in the <span class="hlt">current</span> <span class="hlt">sheet</span> and estimate the density. Ulysses was directly above the location of the CME and intercepted the ejecta. High ionization state Fe was detected by SWICS throughout the magnetic cloud associated with the CME, although the rapid temporal variation suggests bursty, rather than smooth, reconnection in the coronal <span class="hlt">current</span> <span class="hlt">sheet</span>. Both the remote and in situ observations are compared with predictions of theoretical CME models.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22275816-graphene-electron-cannon-high-current-edge-emission-from-aligned-graphene-sheets','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22275816-graphene-electron-cannon-high-current-edge-emission-from-aligned-graphene-sheets"><span>Graphene electron cannon: High-<span class="hlt">current</span> edge emission from aligned graphene <span class="hlt">sheets</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Liu, Jianlong; Li, Nannan; Guo, Jing</p> <p>2014-01-13</p> <p>High-<span class="hlt">current</span> field emitters are made by graphene paper consist of aligned graphene <span class="hlt">sheets</span>. Field emission luminance pattern shows that their electron beams can be controlled by rolling the graphene paper from <span class="hlt">sheet</span> to cylinder. These specific electron beams would be useful to vacuum devices and electron beam lithograph. To get high-<span class="hlt">current</span> emission, the graphene paper is rolled to array and form graphene cannon. Due to aligned emission array, graphene cannon have high emission <span class="hlt">current</span>. Besides high emission <span class="hlt">current</span>, the graphene cannon is also tolerable with excellent emission stability. With good field emission properties, these aligned graphene emitters bring application insight.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22304083-nonlinear-evolution-three-dimensional-instabilities-thin-thick-electron-scale-current-sheets-plasmoid-formation-current-filamentation','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22304083-nonlinear-evolution-three-dimensional-instabilities-thin-thick-electron-scale-current-sheets-plasmoid-formation-current-filamentation"><span>Nonlinear evolution of three-dimensional instabilities of thin and thick electron scale <span class="hlt">current</span> <span class="hlt">sheets</span>: Plasmoid formation and <span class="hlt">current</span> filamentation</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Jain, Neeraj; Büchner, Jörg; Max Planck Institute for Solar System Research, Justus-Von-Liebig-Weg-3, Göttingen</p> <p></p> <p>Nonlinear evolution of three dimensional electron shear flow instabilities of an electron <span class="hlt">current</span> <span class="hlt">sheet</span> (ECS) is studied using electron-magnetohydrodynamic simulations. The dependence of the evolution on <span class="hlt">current</span> <span class="hlt">sheet</span> thickness is examined. For thin <span class="hlt">current</span> <span class="hlt">sheets</span> (half thickness =d{sub e}=c/ω{sub pe}), tearing mode instability dominates. In its nonlinear evolution, it leads to the formation of oblique <span class="hlt">current</span> channels. Magnetic field lines form 3-D magnetic spirals. Even in the absence of initial guide field, the out-of-reconnection-plane magnetic field generated by the tearing instability itself may play the role of guide field in the growth of secondary finite-guide-field instabilities. For thicker <span class="hlt">current</span> sheetsmore » (half thickness ∼5 d{sub e}), both tearing and non-tearing modes grow. Due to the non-tearing mode, <span class="hlt">current</span> <span class="hlt">sheet</span> becomes corrugated in the beginning of the evolution. In this case, tearing mode lets the magnetic field reconnect in the corrugated ECS. Later thick ECS develops filamentary structures and turbulence in which reconnection occurs. This evolution of thick ECS provides an example of reconnection in self-generated turbulence. The power spectra for both the thin and thick <span class="hlt">current</span> <span class="hlt">sheets</span> are anisotropic with respect to the electron flow direction. The cascade towards shorter scales occurs preferentially in the direction perpendicular to the electron flow.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19850059351&hterms=Electric+current&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3DElectric%2Bcurrent','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19850059351&hterms=Electric+current&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3DElectric%2Bcurrent"><span>Electric and magnetic drift of non-adiabatic ions in the earth's geomagnetic <span class="hlt">tail</span> <span class="hlt">current</span> <span class="hlt">sheet</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Beard, D. B.; Cowley, S. W. H.</p> <p>1985-01-01</p> <p>It has been shown recently that nonadiabatic particles in the earth's magnetotail drift across the <span class="hlt">tail</span> roughly as predicted for adiabatic particles with 90 deg pitch angles. In this paper it is shown that this result implies the existence of an approximate invariant of the motion. Adding the effect of convection associated electric fields, the approximate bounce averaged motion of nonadiabatic particles in the magnetotail can be obtained. Thus the particle motion and energization due to combined magnetic and electric drifts in the magnetotail are easily predicted.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018PhPl...25c2113P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018PhPl...25c2113P"><span>Onset of fast "ideal" tearing in thin <span class="hlt">current</span> <span class="hlt">sheets</span>: Dependence on the equilibrium <span class="hlt">current</span> profile</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pucci, F.; Velli, M.; Tenerani, A.; Del Sarto, D.</p> <p>2018-03-01</p> <p>In this paper, we study the scaling relations for the triggering of the fast, or "ideal," tearing instability starting from equilibrium configurations relevant to astrophysical as well as laboratory plasmas that differ from the simple Harris <span class="hlt">current</span> <span class="hlt">sheet</span> configuration. We present the linear tearing instability analysis for equilibrium magnetic fields which (a) go to zero at the boundary of the domain and (b) contain a double <span class="hlt">current</span> <span class="hlt">sheet</span> system (the latter previously studied as a Cartesian proxy for the m = 1 kink mode in cylindrical plasmas). More generally, we discuss the critical aspect ratio scalings at which the growth rates become independent of the Lundquist number S, in terms of the dependence of the Δ' parameter on the wavenumber k of unstable modes. The scaling Δ'(k) with k at small k is found to categorize different equilibria broadly: the critical aspect ratios may be even smaller than L/a ˜ Sα with α = 1/3 originally found for the Harris <span class="hlt">current</span> <span class="hlt">sheet</span>, but there exists a general lower bound α ≥ 1/4.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMSH42A..04B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMSH42A..04B"><span>Distribution of Plasmoids in Post-Coronal Mass Ejection <span class="hlt">Current</span> <span class="hlt">Sheets</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bhattacharjee, A.; Guo, L.; Huang, Y.</p> <p>2013-12-01</p> <p>Recently, the fragmentation of a <span class="hlt">current</span> <span class="hlt">sheet</span> in the high-Lundquist-number regime caused by the plasmoid instability has been proposed as a possible mechanism for fast reconnection. In this work, we investigate this scenario by comparing the distribution of plasmoids obtained from Large Angle and Spectrometric Coronagraph (LASCO) observational data of a coronal mass ejection event with a resistive magnetohydrodynamic simulation of a similar event. The LASCO/C2 data are analyzed using visual inspection, whereas the numerical data are analyzed using both visual inspection and a more precise topological method. Contrasting the observational data with numerical data analyzed with both methods, we identify a major limitation of the visual inspection method, due to the difficulty in resolving smaller plasmoids. This result raises questions about reports of log-normal distributions of plasmoids and other coherent features in the recent literature. Based on nonlinear scaling relations of the plasmoid instability, we infer a lower bound on the <span class="hlt">current</span> <span class="hlt">sheet</span> width, assuming the underlying mechanism of <span class="hlt">current</span> <span class="hlt">sheet</span> broadening is resistive diffusion.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19900054857&hterms=magnetic+cooling&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dmagnetic%2Bcooling','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19900054857&hterms=magnetic+cooling&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dmagnetic%2Bcooling"><span>Heating and cooling of the earth's plasma <span class="hlt">sheet</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Goertz, C. K.</p> <p>1990-01-01</p> <p>Magnetic-field models based on pressure equilibrium in the quiet magnetotail require nonadiabatic cooling of the plasma as it convects inward or a decrease of the flux tube content. Recent in situ observations of plasma density and temperature indicate that, during quiet convection, the flux tube content may actually increase. Thus the plasma must be cooled during quiet times. The earth plasma <span class="hlt">sheet</span> is generally significantly hotter after the expansion phase of a substorm than before the plasma <span class="hlt">sheet</span> thinning begins and cools during the recovery phase. Heating mechanisms such as reconnection, <span class="hlt">current</span> <span class="hlt">sheet</span> acceleration, plasma expansion, and resonant absorption of surface waves are discussed. It seems that all mechanisms are active, albeit in different regions of the plasma <span class="hlt">sheet</span>. Near-earth <span class="hlt">tail</span> signatures of substorms require local heating as well as a decrease of the flux tube content. It is shown that the resonant absorption of surface waves can provide both.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19720058742&hterms=BALANCE+SHEET&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DBALANCE%2BSHEET','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19720058742&hterms=BALANCE+SHEET&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DBALANCE%2BSHEET"><span>On the balance of stresses in the plasma <span class="hlt">sheet</span>.</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Rich, F. J.; Wolf, R. A.; Vasyliunas, V. M.</p> <p>1972-01-01</p> <p>The stress resulting from magnetic tension on the neutral <span class="hlt">sheet</span> must, in a steady state, be balanced by any one or a combination of (1) a pressure gradient in the direction along the axis of the <span class="hlt">tail</span>, (2) a similar gradient of plasma flow kinetic energy, and (3) the tension resulting from a pressure anisotropy within the plasma <span class="hlt">sheet</span>. Stress balance in the first two cases requires that the ratios h/LX and BZ/BX be of the same order of magnitude, where h is the half-thickness of the neutral <span class="hlt">sheet</span>, LX is the length scale for variations along the axis of the <span class="hlt">tail</span>, and BZ and BX are the magnetic field components in the plasma <span class="hlt">sheet</span> just outside the neutral <span class="hlt">sheet</span>. The second case requires, in addition, that the plasma flow speed within the neutral <span class="hlt">sheet</span> be of the order of or larger than the Alfven speed outside the neutral <span class="hlt">sheet</span>. Stress balance in the third case requires that just outside the neutral <span class="hlt">sheet</span> the plasma pressure obey the marginal firehose stability condition.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19950045382&hterms=method+magnetic&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dmethod%2Bmagnetic','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19950045382&hterms=method+magnetic&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dmethod%2Bmagnetic"><span>Method for confining the magnetic field of the cross-<span class="hlt">tail</span> <span class="hlt">current</span> inside the magnetopause</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Sotirelis, T.; Tsyganenko, N. A.; Stern, D. P.</p> <p>1994-01-01</p> <p>A method is presented for analytically representing the magnetic field due to the cross-<span class="hlt">tail</span> <span class="hlt">current</span> and its closure on the magnetopause. It is an extension of a method used by Tsyganenko (1989b) to confine the dipole field inside an ellipsoidal magnetopause using a scalar potential. Given a model of the cross-<span class="hlt">tail</span> <span class="hlt">current</span>, the implied net magnetic field is obtained by adding to the cross-<span class="hlt">tail</span> <span class="hlt">current</span> field a potential field B = - del gamma, which makes all field lines divide into two disjoint groups, separated by the magnetopause (i.e., the combined field is made to have zero normal component with the magnetopause). The magnetopause is assumed to be an ellipsoid of revolution (a prolate spheroid) as an approximation to observations (Sibeck et al., 1991). This assumption permits the potential gamma to be expressed in spheroidal coordinates, expanded in spheroidal harmonics and its terms evaluated by performing inversion integrals. Finally, the field outside the magnetopause is replaced by zero, resulting in a consistent <span class="hlt">current</span> closure along the magnetopause. This procedure can also be used to confine the modeled field of any other interior magnetic source, though the model <span class="hlt">current</span> must always flow in closed circuits. The method is demonstrated on the T87 cross-<span class="hlt">tail</span> <span class="hlt">current</span>, examples illustrate the effect of changing the size and shape of the prescribed magnetopause and a comparison is made to an independent numerical scheme based on the Biot-Savart equation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22410427-instability-current-sheets-localized-accumulation-magnetic-flux','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22410427-instability-current-sheets-localized-accumulation-magnetic-flux"><span>Instability of <span class="hlt">current</span> <span class="hlt">sheets</span> with a localized accumulation of magnetic flux</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Pritchett, P. L.</p> <p>2015-06-15</p> <p>The longstanding problem of whether a <span class="hlt">current</span> <span class="hlt">sheet</span> with curved magnetic field lines associated with a small “normal” B{sub z} component is stable is investigated using two-dimensional electromagnetic particle-in-cell simulations, employing closed boundary conditions analogous to those normally assumed in energy principle calculations. Energy principle arguments [Sitnov and Schindler, Geophys. Res. Lett. 37, L08102 (2010)] have suggested that an accumulation of magnetic flux at the tailward end of a thin <span class="hlt">current</span> <span class="hlt">sheet</span> could produce a tearing instability. Two classes of such <span class="hlt">current</span> <span class="hlt">sheet</span> configurations are probed: one with a monotonically increasing B{sub z} profile and the other with a localizedmore » B{sub z} “hump.” The former is found to be stable (in 2D) over any reasonable time scale, while the latter is prone to an ideal-like instability that shifts the hump peak in the direction of the curvature normal and erodes the field on the opposite side. The growth rate of this instability is smaller by an order of magnitude than previous suggestions of an instability in an open system. An example is given that suggests that such an unstable hump configuration is unlikely to be produced by external driving of a <span class="hlt">current</span> <span class="hlt">sheet</span> with no B{sub z} accumulation even in the presence of open boundary conditions.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMSH54A..05S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMSH54A..05S"><span>Exploring reconnection, <span class="hlt">current</span> <span class="hlt">sheets</span>, and dissipation in a laboratory MHD turbulence experiment</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schaffner, D. A.</p> <p>2015-12-01</p> <p>The Swarthmore Spheromak Experiment (SSX) can serve as a testbed for studying MHD turbulence in a controllable laboratory setting, and in particular, explore the phenomena of reconnection, <span class="hlt">current</span> <span class="hlt">sheets</span> and dissipation in MHD turbulence. Plasma with turbulently fluctuating magnetic and velocity fields can be generated using a plasma gun source and launched into a flux-conserving cylindrical tunnel. No background magnetic field is applied so internal fields are allowed to evolve dynamically. Point measurements of magnetic and velocity fluctuations yield broadband power-law spectra with a steepening breakpoint indicative of the onset of a dissipation scale. The frequency range at which this steepening occurs can be correlated to the ion inertial scale of the plasma, a length which is characteristic of the size of <span class="hlt">current</span> <span class="hlt">sheets</span> in MHD plasmas and suggests a connection to dissipation. Observation of non-Gaussian intermittent jumps in magnetic field magnitude and angle along with measurements of ion temperature bursts suggests the presence of <span class="hlt">current</span> <span class="hlt">sheets</span> embedded within the turbulent plasma, and possibly even active reconnection sites. Additionally, structure function analysis coupled with appeals to fractal scaling models support the hypothesis that <span class="hlt">current</span> <span class="hlt">sheets</span> are associated with dissipation in this system.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19790061528&hterms=1055&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3D%2526%25231055','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19790061528&hterms=1055&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3D%2526%25231055"><span>Radial deformation of the solar <span class="hlt">current</span> <span class="hlt">sheet</span> as a cause of geomagnetic storms</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Akasofu, S.-I.</p> <p>1979-01-01</p> <p>It is suggested that the solar <span class="hlt">current</span> <span class="hlt">sheet</span>, extending from a coronal streamer, develops a large-scale radial deformation, at times with a very steep gradient at the earth's distance. The associated magnetic field lines (namely, the interplanetary magnetic field (IMF) lines) are expected to have also a large gradient in the vicinity of the <span class="hlt">current</span> <span class="hlt">sheet</span>. It is also suggested that some of the major geomagnetic storms occur when the earth is located in the region where IMF field lines have a large dip angle with respect to the ecliptic plane for an extended period (6-48 h), as a result of a steep radial deformation of the <span class="hlt">current</span> <span class="hlt">sheet</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19950056440&hterms=GERD&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DGERD','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19950056440&hterms=GERD&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DGERD"><span>A magnetospheric magnetic field model with flexible <span class="hlt">current</span> systems driven by independent physical parameters</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hilmer, Robert V.; Voigt, Gerd-Hannes</p> <p>1995-01-01</p> <p>A tilt-dependent magnetic field model of the Earth's magnetosphere with variable magnetopause standoff distance is presented. Flexible analytic representations for the ring and cross-<span class="hlt">tail</span> <span class="hlt">currents</span>, each composed of the elements derived from the Tsyganenko and Usmanov (1982) model, are combined with the fully shielded vacuum dipole configurations of Voigt (1981). Although the <span class="hlt">current</span> <span class="hlt">sheet</span> does not warp in the y-z plane, changes in the shape and position of the neutral <span class="hlt">sheet</span> with dipole tilt are consistent with both MHD equilibrium theory and observations. In addition, there is good agreement with observed Delta B profiles and the average equatorial contours of magnetic field magnitude. While the dipole field is rigorously shielded within the defined magnetopause, the ring and cross-<span class="hlt">tails</span> <span class="hlt">currents</span> are not similarly confined, consequently, the model's region of validity is limited to the inner magnetosphere. The model depends on four independent external parameters. We present a simple but limited method of simulating several substorm related magnetic field changes associated with the disrupion of the near-Earth cross-<span class="hlt">tail</span> <span class="hlt">current</span> <span class="hlt">sheet</span> and collapse of the midnight magnetotail field region. This feature further facilitates the generation of magnetic field configuration time sequences useful in plasma convection simulations of real magnetospheric events.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014ApJ...780..103W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014ApJ...780..103W"><span>Evidence for Two Separate Heliospheric <span class="hlt">Current</span> <span class="hlt">Sheets</span> of Cylindrical Shape During Mid-2012</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, Y.-M.; Young, P. R.; Muglach, K.</p> <p>2014-01-01</p> <p>During the reversal of the Sun's polar fields at sunspot maximum, outward extrapolations of magnetograph measurements often predict the presence of two or more <span class="hlt">current</span> <span class="hlt">sheets</span> extending into the interplanetary medium, instead of the single heliospheric <span class="hlt">current</span> <span class="hlt">sheet</span> (HCS) that forms the basis of the standard "ballerina skirt" picture. By comparing potential-field source-surface models of the coronal streamer belt with white-light coronagraph observations, we deduce that the HCS was split into two distinct structures with circular cross sections during mid-2012. These cylindrical <span class="hlt">current</span> <span class="hlt">sheets</span> were centered near the heliographic equator and separated in longitude by roughly 180° a corresponding four-sector polarity pattern was observed at Earth. Each cylinder enclosed a negative-polarity coronal hole that was identifiable in extreme ultraviolet images and gave rise to a high-speed stream. The two <span class="hlt">current</span> <span class="hlt">sheet</span> systems are shown to be a result of the dominance of the Sun's nonaxisymmetric quadrupole component, as the axial dipole field was undergoing its reversal during solar cycle 24.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20150007963','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20150007963"><span>Evidence for Two Separate Heliospheric <span class="hlt">Current</span> <span class="hlt">Sheets</span> of Cylindrical Shape During Mid-2012</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Wang, Y.-M.; Young, P. R.; Muglach, K.</p> <p>2013-01-01</p> <p>During the reversal of the Sun's polar fields at sunspot maximum, outward extrapolations of magnetograph measurements often predict the presence of two or more <span class="hlt">current</span> <span class="hlt">sheets</span> extending into the interplanetary medium, instead of the single heliospheric <span class="hlt">current</span> <span class="hlt">sheet</span> (HCS) that forms the basis of the standard 'ballerina skirt' picture. By comparing potential-field source-surface models of the coronal streamer belt with white-light coronagraph observations, we deduce that the HCS was split into two distinct structures with circular cross sections during mid-2012. These cylindrical <span class="hlt">current</span> <span class="hlt">sheets</span> were centered near the heliographic equator and separated in longitude by roughly 180 deg; a corresponding four-sector polarity pattern was observed at Earth. Each cylinder enclosed a negative-polarity coronal hole that was identifiable in extreme ultraviolet images and gave rise to a high-speed stream. The two <span class="hlt">current</span> <span class="hlt">sheet</span> systems are shown to be a result of the dominance of the Sun's nonaxisymmetric quadrupole component, as the axial dipole field was undergoing its reversal during solar cycle 24.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018ApJ...858L...4X','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018ApJ...858L...4X"><span>Spectral and Imaging Observations of a <span class="hlt">Current</span> <span class="hlt">Sheet</span> Region in a Small-scale Magnetic Reconnection Event</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Xue, Zhike; Yan, Xiaoli; Yang, Liheng; Wang, Jincheng; Feng, Song; Li, Qiaoling; Ji, Kaifan; Zhao, Li</p> <p>2018-05-01</p> <p>We report a possible <span class="hlt">current</span> <span class="hlt">sheet</span> region associated with a small-scale magnetic reconnection event by using the spectral and imaging observations of the Interface Region Imaging Spectrograph (IRIS) and the magnetograms obtained by the Solar Dynamics Observatory on 2016 August 08. The length and width of the <span class="hlt">current</span> <span class="hlt">sheet</span> region are estimated to be from 1.4 ± 0.1 Mm to 3.0 ± 0.3 Mm and from 0.34 ± 0.01 Mm to 0.64 ± 0.09 Mm, respectively. The evolutions of the length of the <span class="hlt">current</span> <span class="hlt">sheet</span> region are positively correlated with that of the width. These measurements are among the smallest reported. When the IRIS slit scans the <span class="hlt">current</span> <span class="hlt">sheet</span> region, the spectroscopic observations show that the Si IV line is broadened in the <span class="hlt">current</span> <span class="hlt">sheet</span> region and the plasma has a blueshifted feature at the middle and a redshifted feature at the ends of the <span class="hlt">current</span> <span class="hlt">sheet</span> region. The maximum measured blueshifted and redshifted Doppler velocities are ‑20.8 ± 0.9 and 34.1 ± 0.4 km s‑1, respectively. Additionally, the electron number densities of the plasma in the <span class="hlt">current</span> <span class="hlt">sheet</span> region are computed to be around 1011 cm‑3 based on the spectrums of the two O IV lines. The emergence, movement, and cancellation of a small sunspot with negative polarity are observed during the formation and shift of the <span class="hlt">current</span> <span class="hlt">sheet</span> region. We suggest that the occurrence and evolution of the magnetic reconnection are driven by the movement of the small sunspot in the photosphere.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li class="active"><span>6</span></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_6 --> <div id="page_7" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li class="active"><span>7</span></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="121"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMSM21A..04K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMSM21A..04K"><span>Impact of Near-Earth Plasma <span class="hlt">Sheet</span> Dynamics on the Ring <span class="hlt">Current</span> Composition</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kistler, L. M.; Mouikis, C.; Menz, A.; Spence, H. E.; Mitchell, D. G.; Gkioulidou, M.; Lanzerotti, L. J.; Skoug, R. M.; Larsen, B.; Claudepierre, S. G.; Fennell, J. F.; Blake, J. B.</p> <p>2014-12-01</p> <p>How the dynamics in the near-earth plasma <span class="hlt">sheet</span> affects the heavy ion content, and therefore the ion pressure, of the ring <span class="hlt">current</span> in Earth's magnetosphere is an outstanding question. Substorms accelerate plasma in the near-earth region and drive outflow from the aurora, and both these processes can preferentially enhance the population of heavy ions in this region. These heavy ions are then driven into the inner magnetosphere during storms. Thus understanding how the composition of the ring <span class="hlt">current</span> changes requires simultaneous observations in the near-earth plasma <span class="hlt">sheet</span> and in the inner magnetosphere. We use data from the CODIF instrument on Cluster and HOPE, RBSPICE, and MagEIS instruments on the Van Allen Probes to study the acceleration and transport of ions from the plasma <span class="hlt">sheet</span> into the ring <span class="hlt">current</span>. During the main phase of a geomagnetic storm on Aug 4-6, 2013, the Cluster spacecraft were moving inbound in the midnight central plasma <span class="hlt">sheet</span>, while the apogees of the two Van Allen Probes were located on the duskside. The Cluster spacecraft measure the composition and spectral changes in the plasma <span class="hlt">sheet</span>, while the Van Allen Probes measure the ions that reach the inner magnetosphere. A strong increase in 1-40 keV O+ was observed at the Cluster location during the storm main phase, and the Van Allen Probes observed both H+ and O+ being driven deep into the inner magnetosphere. By comparing the variations in phase space density (PSD) vs. magnetic moment at the Cluster and the Van Allen Probes locations, we examine how the composition changes non-adiabatically in the near-earth plasma <span class="hlt">sheet</span>, and how those changes are propagated into the inner magnetosphere, populating the hto ion ring <span class="hlt">current</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015SZF.....1a...4L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015SZF.....1a...4L"><span>MHD-waves in the geomagnetic <span class="hlt">tail</span>: A review</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Leonovich, Anatoliy; Mazur, Vitaliy; Kozlov, Daniil</p> <p>2015-03-01</p> <p>This article presents the review of experimental and theoretical studies on ultra-lowfrequency MHD oscillations of the geomagnetic <span class="hlt">tail</span>. We consider the Kelvin-Helmholtz instability at the magnetopause, oscillations with a discrete spectrum in the "magic frequencies"range, the ballooning instability of coupled Alfvén and slow magnetosonic waves, and "flapping" oscillations of the <span class="hlt">current</span> <span class="hlt">sheet</span> of the geomagnetic <span class="hlt">tail</span>. Over the last decade, observations from THEMIS, CLUSTER and Double Star satellites have been of great importance for experimental studies. The use of several spacecraft allows us to study the structure of MHD oscillations with high spatial resolution. Due to this, we can make a detailed comparison between theoretical results and those obtained from multi-spacecraft studies. To make such comparisons in theoretical studies, in turn, we have to use the numerical models closest to the real magnetosphere.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018ApJ...859...83S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018ApJ...859...83S"><span>Marginal Stability of Sweet–Parker Type <span class="hlt">Current</span> <span class="hlt">Sheets</span> at Low Lundquist Numbers</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Shi, Chen; Velli, Marco; Tenerani, Anna</p> <p>2018-06-01</p> <p>Magnetohydrodynamic simulations have shown that a nonunique critical Lundquist number S c exists, hovering around S c ∼ 104, above which threshold Sweet–Parker type stationary reconnecting configurations become unstable to a fast tearing mode dominated by plasmoid generation. It is known that the flow along the <span class="hlt">sheet</span> plays a stabilizing role, though a satisfactory explanation of the nonuniversality and variable critical Lundquist numbers observed is still lacking. Here we discuss this question using 2D linear MHD simulations and linear stability analyses of Sweet–Parker type <span class="hlt">current</span> <span class="hlt">sheets</span> in the presence of background stationary inflows and outflows at low Lundquist numbers (S ≤ 104). Simulations show that the inhomogeneous outflow stabilizes the <span class="hlt">current</span> <span class="hlt">sheet</span> by stretching the growing magnetic islands and at the same time evacuating the magnetic islands out of the <span class="hlt">current</span> <span class="hlt">sheet</span>. This limits the time during which fluctuations that begin at any given wavelength can remain unstable, rendering the instability nonexponential. We find that the linear theory based on the expanding-wavelength assumption works well for S larger than ∼1000. However, we also find that the inflow and location of the initial perturbation also affect the stability threshold.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018PhPl...25e3506L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018PhPl...25e3506L"><span><span class="hlt">Current</span> <span class="hlt">sheet</span> characteristics of a parallel-plate electromagnetic plasma accelerator operated in gas-prefilled mode</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Liu, Shuai; Huang, Yizhi; Guo, Haishan; Lin, Tianyu; Huang, Dong; Yang, Lanjun</p> <p>2018-05-01</p> <p>The axial characteristics of a <span class="hlt">current</span> <span class="hlt">sheet</span> in a parallel-plate electromagnetic plasma accelerator operated in gas-prefilled mode are reported. The accelerator is powered by a fourteen stage pulse forming network. The capacitor and inductor in each stage are 1.5 μF and 300 nH, respectively, and yield a damped oscillation square wave of <span class="hlt">current</span> with a pulse width of 20.6 μs. Magnetic probes and photodiodes are placed at various axial positions to measure the behavior of the <span class="hlt">current</span> <span class="hlt">sheet</span>. Both magnetic probe and photodiode signals reveal a secondary breakdown when the <span class="hlt">current</span> reverses the direction. An increase in the discharge <span class="hlt">current</span> amplitude and a decrease in pressure lead to a decrease in the <span class="hlt">current</span> shedding factor. The <span class="hlt">current</span> <span class="hlt">sheet</span> velocity and thickness are nearly constant during the run-down phase under the first half-period of the <span class="hlt">current</span>. The <span class="hlt">current</span> <span class="hlt">sheet</span> thicknesses are typically in the range of 25 mm to 40 mm. The <span class="hlt">current</span> <span class="hlt">sheet</span> velocities are in the range of 10 km/s to 45 km/s when the discharge <span class="hlt">current</span> is between 10 kA and 55 kA and the gas prefill pressure is between 30 Pa and 800 Pa. The experimental velocities are about 75% to 90% of the theoretical velocities calculated with the <span class="hlt">current</span> shedding factor. One reason for this could be that the idealized snowplow analysis model ignores the surface drag force.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008ArRMA.187..369C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008ArRMA.187..369C"><span>Existence and Stability of Compressible <span class="hlt">Current</span>-Vortex <span class="hlt">Sheets</span> in Three-Dimensional Magnetohydrodynamics</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chen, Gui-Qiang; Wang, Ya-Guang</p> <p>2008-03-01</p> <p>Compressible vortex <span class="hlt">sheets</span> are fundamental waves, along with shocks and rarefaction waves, in entropy solutions to multidimensional hyperbolic systems of conservation laws. Understanding the behavior of compressible vortex <span class="hlt">sheets</span> is an important step towards our full understanding of fluid motions and the behavior of entropy solutions. For the Euler equations in two-dimensional gas dynamics, the classical linearized stability analysis on compressible vortex <span class="hlt">sheets</span> predicts stability when the Mach number M > sqrt{2} and instability when M < sqrt{2} ; and Artola and Majda’s analysis reveals that the nonlinear instability may occur if planar vortex <span class="hlt">sheets</span> are perturbed by highly oscillatory waves even when M > sqrt{2} . For the Euler equations in three dimensions, every compressible vortex <span class="hlt">sheet</span> is violently unstable and this instability is the analogue of the Kelvin Helmholtz instability for incompressible fluids. The purpose of this paper is to understand whether compressible vortex <span class="hlt">sheets</span> in three dimensions, which are unstable in the regime of pure gas dynamics, become stable under the magnetic effect in three-dimensional magnetohydrodynamics (MHD). One of the main features is that the stability problem is equivalent to a free-boundary problem whose free boundary is a characteristic surface, which is more delicate than noncharacteristic free-boundary problems. Another feature is that the linearized problem for <span class="hlt">current</span>-vortex <span class="hlt">sheets</span> in MHD does not meet the uniform Kreiss Lopatinskii condition. These features cause additional analytical difficulties and especially prevent a direct use of the standard Picard iteration to the nonlinear problem. In this paper, we develop a nonlinear approach to deal with these difficulties in three-dimensional MHD. We first carefully formulate the linearized problem for the <span class="hlt">current</span>-vortex <span class="hlt">sheets</span> to show rigorously that the magnetic effect makes the problem weakly stable and establish energy estimates, especially high-order energy</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20110009938','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20110009938"><span>Formation and Reconnection of Three-Dimensional <span class="hlt">Current</span> <span class="hlt">Sheets</span> in the Solar Corona</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Edmondson, J. K.; Antiochos, S. K.; DeVore, C. R.; Zurbuchen, T. H.</p> <p>2010-01-01</p> <p><span class="hlt">Current-sheet</span> formation and magnetic reconnection are believed to be the basic physical processes responsible for much of the activity observed in astrophysical plasmas, such as the Sun s corona. We investigate these processes for a magnetic configuration consisting of a uniform background field and an embedded line dipole, a topology that is expected to be ubiquitous in the corona. This magnetic system is driven by a uniform horizontal flow applied at the line-tied photosphere. Although both the initial field and the driver are translationally symmetric, the resulting evolution is calculated using a fully three-dimensional magnetohydrodynamic (3D MHD) simulation with adaptive mesh refinement that resolves the <span class="hlt">current</span> <span class="hlt">sheet</span> and reconnection dynamics in detail. The advantage of our approach is that it allows us to apply directly the vast body of knowledge gained from the many studies of 2D reconnection to the fully 3D case. We find that a <span class="hlt">current</span> <span class="hlt">sheet</span> forms in close analogy to the classic Syrovatskii 2D mechanism, but the resulting evolution is different than expected. The <span class="hlt">current</span> <span class="hlt">sheet</span> is globally stable, showing no evidence for a disruption or a secondary instability even for aspect ratios as high as 80:1. The global evolution generally follows the standard Sweet- Parker 2D reconnection model except for an accelerated reconnection rate at a very thin <span class="hlt">current</span> <span class="hlt">sheet</span>, due to the tearing instability and the formation of magnetic islands. An interesting conclusion is that despite the formation of fully 3D structures at small scales, the system remains close to 2D at global scales. We discuss the implications of our results for observations of the solar corona. Subject Headings: Sun: corona Sun: magnetic fields Sun: reconnection</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014cosp...40E.893F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014cosp...40E.893F"><span>Effect of Time Dependent Bending of <span class="hlt">Current</span> <span class="hlt">Sheets</span> in Response to Generation of Plasma Jets and Reverse <span class="hlt">Currents</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Frank, Anna</p> <p></p> <p>Magnetic reconnection is a basis for many impulsive phenomena in space and laboratory plasmas accompanied by effective transformation of magnetic energy. Reconnection processes usually occur in relatively thin <span class="hlt">current</span> <span class="hlt">sheets</span> (CSs), which separate magnetic fields of different or opposite directions. We report on recent observations of time dependent bending of CSs, which results from plasma dynamics inside the <span class="hlt">sheet</span>. The experiments are carried out with the CS-3D laboratory device (Institute of General Physics RAS, Moscow) [1]. The CS magnetic structure with an X line provides excitation of the Hall <span class="hlt">currents</span> and plasma acceleration from the X line to both side edges [2]. In the presence of the guide field By the Hall <span class="hlt">currents</span> give rise to bending of the <span class="hlt">sheet</span>: the peripheral regions located away from the X line are deflected from CS middle plane (z=0) in the opposite directions ±z [3]. We have revealed generation of reverse <span class="hlt">currents</span> jy near the CS edges, i.e. the <span class="hlt">currents</span> flowing in the opposite direction to the main <span class="hlt">current</span> in the <span class="hlt">sheet</span> [4]. There are strong grounds to believe that reverse <span class="hlt">currents</span> are generated by the outflow plasma jets [5], accelerated inside the <span class="hlt">sheet</span> and penetrated into the regions with strong normal magnetic field component Bz [4]. An impressive effect of sudden change in the sign of the CS bend has been disclosed recently, when analyzing distributions of plasma density [6] and <span class="hlt">current</span> away from the X line, in the presence of the guide field By. The CS configuration suddenly becomes opposite from that observed at the initial stage, and this effect correlates well with generation of reverse <span class="hlt">currents</span>. Consequently this effect can be related to excitation of the reverse Hall <span class="hlt">currents</span> owing to generation of reverse <span class="hlt">currents</span> jy in the CS. Hence it may be concluded that CSs may exhibit time dependent vertical z-displacements, and the <span class="hlt">sheet</span> geometry depends on excitation of the Hall <span class="hlt">currents</span>, acceleration of plasma jets and generation of reverse</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1994hcds.rept.....C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1994hcds.rept.....C"><span>High <span class="hlt">current</span> density <span class="hlt">sheet</span>-like electron beam generator</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chow-Miller, Cora; Korevaar, Eric; Schuster, John</p> <p></p> <p><span class="hlt">Sheet</span> electron beams are very desirable for coupling to the evanescent waves in small millimeter wave slow-wave circuits to achieve higher powers. In particular, they are critical for operation of the free-electron-laser-like Orotron. The program was a systematic effort to establish a solid technology base for such a <span class="hlt">sheet</span>-like electron emitter system that will facilitate the detailed studies of beam propagation stability. Specifically, the effort involved the design and test of a novel electron gun using Lanthanum hexaboride (LaB6) as the thermionic cathode material. Three sets of experiments were performed to measure beam propagation as a function of collector <span class="hlt">current</span>, beam voltage, and heating power. The design demonstrated its reliability by delivering 386.5 hours of operation throughout the weeks of experimentation. In addition, the cathode survived two venting and pump down cycles without being poisoned or losing its emission characteristics. A <span class="hlt">current</span> density of 10.7 A/sq cm. was measured while operating at 50 W of ohmic heating power. Preliminary results indicate that the nearby presence of a metal plate can stabilize the beam.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1995SoPh..158...43M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1995SoPh..158...43M"><span>Non-Evolutionarity of a Reconnecting <span class="hlt">Current</span> <span class="hlt">Sheet</span> as a Cause of Its Splitting into MHD Shocks</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Markovsky, S. A.; Somov, B. V.</p> <p>1995-04-01</p> <p>Numerical simulations of the magnetic reconnection process in a <span class="hlt">current</span> <span class="hlt">sheet</span> show that, in some cases, MHD shocks appear to be attached to edges of the <span class="hlt">sheet</span>. The appearance of the shocks may be considered to be a result of splitting of the <span class="hlt">sheet</span>. In the present paper we suppose that this splitting takes place in consequence of non-evolutionarity of the reconnecting <span class="hlt">current</span> <span class="hlt">sheet</span> as a discontinuity. The problem of time evolution of small perturbations does not have a unique solution for a non-evolutionary discontinuity, and it splits into other (evolutionary) discontinuities. Such an approach allows us to determine conditions under which the splitting of the-<span class="hlt">sheet</span> occurs. The main difficulty of this approach is that a <span class="hlt">current</span> <span class="hlt">sheet</span> is not reduced to a classified 1D discontinuity, because inhomogeneity of flow velocity inside the <span class="hlt">sheet</span> is two-dimensional. To formulate the non-evolutionarity problem, we solve the linear MHD equations inside and outside the <span class="hlt">sheet</span> and deduce linearized 1D boundary conditions at its surface. We show that for large enough conductivity, small perturbations exist which interact with the <span class="hlt">sheet</span> as with a discontinuity. Then we obtain a non-evolutionarity criterion, with respect to these perturbations, in the form of a restriction on the flow velocity across the surface of the <span class="hlt">sheet</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19730027259&hterms=plasma+focus&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dplasma%2Bfocus','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19730027259&hterms=plasma+focus&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dplasma%2Bfocus"><span><span class="hlt">Current</span> <span class="hlt">sheet</span> collapse in a plasma focus.</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Jalufka, N. W.; Lee, J. H.</p> <p>1972-01-01</p> <p>Collapse of the <span class="hlt">current</span> <span class="hlt">sheets</span> in a plasma focus has been recorded simultaneously through slits parallel and perpendicular to the symmetry axis in the streak mode. The dark period following the collapse is due to the plasma moving out of the field of view. Microdensitometric measurements of intensity variation also support this conclusion. A large anisotropy is also found in the x-ray radiation pattern. Effects of different vacuum vessels were investigated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSH33A2755H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSH33A2755H"><span>Spatially Localized Particle Energization by Landau Damping in <span class="hlt">Current</span> <span class="hlt">Sheets</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Howes, G. G.; Klein, K. G.; McCubbin, A. J.</p> <p>2017-12-01</p> <p>Understanding the mechanisms of particle energization through the removal of energy from turbulent fluctuations in heliospheric plasmas is a grand challenge problem in heliophysics. Under the weakly collisional conditions typical of heliospheric plasma, kinetic mechanisms must be responsible for this energization, but the nature of those mechanisms remains elusive. In recent years, the spatial localization of plasma heating near <span class="hlt">current</span> <span class="hlt">sheets</span> in the solar wind and numerical simulations has gained much attention. Here we show, using the innovative and new field-particle correlation technique, that the spatially localized particle energization occurring in a nonlinear gyrokinetic simulation has the velocity space signature of Landau damping, suggesting that this well-known collisionless damping mechanism indeed actively leads to spatially localized heating in the vicinity of <span class="hlt">current</span> <span class="hlt">sheets</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22118677-magnetar-giant-flares-precursors-flux-rope-eruptions-current-sheets','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22118677-magnetar-giant-flares-precursors-flux-rope-eruptions-current-sheets"><span>MAGNETAR GIANT FLARES AND THEIR PRECURSORS-FLUX ROPE ERUPTIONS WITH <span class="hlt">CURRENT</span> <span class="hlt">SHEETS</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Yu Cong; Huang Lei, E-mail: cyu@ynao.ac.cn, E-mail: muduri@shao.ac.cn</p> <p>2013-07-10</p> <p>We propose a catastrophic magnetospheric model for magnetar precursors and their successive giant flares. Axisymmetric models of the magnetosphere, which contain both a helically twisted flux rope and a <span class="hlt">current</span> <span class="hlt">sheet</span>, are established based on force-free field configurations. In this model, the helically twisted flux rope would lose its equilibrium and erupt abruptly in response to the slow and quasi-static variations at the ultra-strongly magnetized neutron star's surface. In a previous model without <span class="hlt">current</span> <span class="hlt">sheets</span>, only one critical point exists in the flux rope equilibrium curve. New features show up in the equilibrium curves for the flux rope when currentmore » <span class="hlt">sheets</span> appear in the magnetosphere. The causal connection between the precursor and the giant flare, as well as the temporary re-entry of the quiescent state between the precursor and the giant flare, can be naturally explained. Magnetic energy would be released during the catastrophic state transitions. The detailed energetics of the model are also discussed. The <span class="hlt">current</span> <span class="hlt">sheet</span> created by the catastrophic loss of equilibrium of the flux rope provides an ideal place for magnetic reconnection. We point out the importance of magnetic reconnection for further enhancement of the energy release during eruptions.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19870035873&hterms=population+characteristic&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dpopulation%2Bcharacteristic*','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19870035873&hterms=population+characteristic&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dpopulation%2Bcharacteristic*"><span>Characteristics of the <span class="hlt">tail</span> of Comet Giacobini-Zinner</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Scarf, F. L.</p> <p>1986-01-01</p> <p>The physical structure and characteristics of the Comet Giacobini-Zinner <span class="hlt">tail</span> are described. Variations in the vector B-field configuration, the electron distribution function, the energetic ion population, and the electromagnetic and electrostatic plasma wave spectra are analyzed. The ICE detected a two-lobe magnetic field configuration and a narrow central plasma <span class="hlt">sheet</span>. Additional analyses proposed for the Giacobini-Zinner <span class="hlt">tail</span> data are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20050092387&hterms=EIT&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DEIT','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20050092387&hterms=EIT&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DEIT"><span><span class="hlt">Current</span> <span class="hlt">Sheet</span> Evolution in the Aftermath of a CME Event</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Bemporad, A.; Poletto, G.; Suess, S. T.; Ko, Y.-K.; Schwadron, N. A.; Elliott, H. A.; Raymond, J. C.</p> <p>2005-01-01</p> <p>We report on SOHO-UVCS observations of the coronal restructuring following a Coronal Mass Ejection (CME) on November 26,2002, at the time of a SOHO-Ulysses quadrature campaign. Starting about 3 hours after a CME in the NW quadrant, UVCS began taking spectra at 1.7 solar radius, covering emission from both cool and hot plasma. Observations continued, with occasional gaps, for more than 2 days. Emission in the 974.8 Angstrom line of [Fe XVIII], indicating temperatures above 6 x 10(exp 6) K, was observed throughout the campaign in a spatially limited location. Comparison with EIT images shows the Fe XVIII emission to overlie a growing post-flare loop system formed in the aftermath of the CME. The emission most likely originates in a <span class="hlt">current</span> <span class="hlt">sheet</span> overlying the arcade. Analysis of the [Fe XVIII] emission allows us to infer the evolution of physical parameters in the <span class="hlt">current</span> <span class="hlt">sheet</span> over the entire span of our observations: in particular, we give the temperature vs. time in the <span class="hlt">current</span> <span class="hlt">sheet</span> and estimate the density. At the time of the quadrature, Ulysses was directly above the location of the CME and intercepted the ejecta. High ionization state Fe was detected by Ulysses-SWICS throughout the magnetic cloud associated with the CME. Both the remote and in situ observations are compared with predictions of theoretical CME models.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26556183','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26556183"><span>Synergetic catalysis based on the proline <span class="hlt">tailed</span> metalloporphyrin with graphene <span class="hlt">sheet</span> as efficient mimetic enzyme for ultrasensitive electrochemical detection of dopamine.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Yan, Xiaoyi; Gu, Yue; Li, Cong; Tang, Liu; Zheng, Bo; Li, Yaru; Zhang, Zhiquan; Yang, Ming</p> <p>2016-03-15</p> <p>In this paper, linking with the butoxycarbonyl (BOC) protection of proline, a new <span class="hlt">tailed</span> metalloporphyrin with many useful active functions, nickel (II) 5-[4-N-(tert-Butoxycarbonyl)-l-prolinecoxylpropyloxy]phenyl-10,15,20-triphenylporphyrin (NiTBLPyP), was designed and synthesized. And the NiTBLPyP polymer (poly(NiTBLPyP)) was successfully obtained via a low-cost electrochemical method and exploited as an efficient mimic enzyme. Subsequently, a noncovalent nanohybrid of poly(NiTBLPyP) with graphene (rGO) <span class="hlt">sheet</span> (rGO-poly(NiTBLPyP)) was prepared through π-π stacking interaction for the ultrasensitive and selective detection of DA. The nanohybrid was characterized by UV-vis spectroscopy, Fourier transform infrared spectra, Raman spectroscopy, scanning electron microscopy and electrochemical impedance spectroscopy. Due to the excellent electrocatalytic ability of poly(NiTBLPyP) film and aromatic π-π stacking interaction between poly(NiTBLPyP and rGO <span class="hlt">sheet</span>, the obtained rGO-poly(NiTBLPyP) film exhibited a great synergistic amplification effect toward dopamine oxidation. Under optimum experimental conditions, the logarithm of catalytic <span class="hlt">currents</span> showed a good linear relationship with that of the dopamine concentration in the range of 0.01-200 μM with a low detection limit of 1.40 nM. With good sensitivity and selectivity, the present method was applied to the determination of DA in real sample and the results was satisfactory. Thus, the rGO-poly(NiTBLPyP) film is one of the promising mimetic enzyme for electrocatalysis and relevant fields. Copyright © 2015 Elsevier B.V. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016SoPh..291.3725W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016SoPh..291.3725W"><span>LASCO White-Light Observations of Eruptive <span class="hlt">Current</span> <span class="hlt">Sheets</span> Trailing CMEs</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Webb, David F.; Vourlidas, Angelos</p> <p>2016-12-01</p> <p>Many models of eruptive flares or coronal mass ejections (CMEs) involve formation of a <span class="hlt">current</span> <span class="hlt">sheet</span> connecting the ejecting CME flux rope with a magnetic loop arcade. However, there is very limited observational information on the properties and evolution of these structures, hindering progress in understanding eruptive activity from the Sun. In white-light images, narrow coaxial rays trailing the outward-moving CME have been interpreted as <span class="hlt">current</span> <span class="hlt">sheets</span>. Here, we undertake the most comprehensive statistical study of CME-rays to date. We use SOHO/LASCO data, which have a higher cadence, larger field of view, and better sensitivity than any previous coronagraph. We compare our results to a previous study of Solar Maximum Mission (SMM) CMEs, in 1984 - 1989, having candidate magnetic disconnection features at the CME base, about half of which were followed by coaxial bright rays. We examine all LASCO CMEs during two periods of minimum and maximum activity in Solar Cycle 23, resulting in many more events, ˜130 CME-rays, than during SMM. Important results include: The occurrence rate of the rays is ˜11 % of all CMEs during solar minimum, but decreases to ˜7 % at solar maximum; this is most likely related to the more complex coronal background. The rays appear on average 3 - 4 hours after the CME core, and are typically visible for three-fourths of a day. The mean observed <span class="hlt">current</span> <span class="hlt">sheet</span> length over the ray lifetime is ˜12 R_{⊙}, with the longest <span class="hlt">current</span> <span class="hlt">sheet</span> of 18.5 R_{⊙}. The mean CS growth rates are 188 km s^{-1} at minimum and 324 km s^{-1} at maximum. Outward-moving blobs within several rays, which are indicative of reconnection outflows, have average velocities of ˜350 km s^{-1} with small positive accelerations. A pre-existing streamer is blown out in most of the CME-ray events, but half of these are observed to reform within ˜1 day. The long lifetime and long lengths of the CME-rays challenge our <span class="hlt">current</span> understanding of the evolution of the magnetic</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19950038002&hterms=SPIRAL+MODEL&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DSPIRAL%2BMODEL','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19950038002&hterms=SPIRAL+MODEL&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DSPIRAL%2BMODEL"><span>A test of source-surface model predictions of heliospheric <span class="hlt">current</span> <span class="hlt">sheet</span> inclination</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Burton, M. E.; Crooker, N. U.; Siscoe, G. L.; Smith, E. J.</p> <p>1994-01-01</p> <p>The orientation of the heliospheric <span class="hlt">current</span> <span class="hlt">sheet</span> predicted from a source surface model is compared with the orientation determined from minimum-variance analysis of International Sun-Earth Explorer (ISEE) 3 magnetic field data at 1 AU near solar maximum. Of the 37 cases analyzed, 28 have minimum variance normals that lie orthogonal to the predicted Parker spiral direction. For these cases, the correlation coefficient between the predicted and measured inclinations is 0.6. However, for the subset of 14 cases for which transient signatures (either interplanetary shocks or bidirectional electrons) are absent, the agreement in inclinations improves dramatically, with a correlation coefficient of 0.96. These results validate not only the use of the source surface model as a predictor but also the previously questioned usefulness of minimum variance analysis across complex sector boundaries. In addition, the results imply that interplanetary dynamics have little effect on <span class="hlt">current</span> <span class="hlt">sheet</span> inclination at 1 AU. The dependence of the correlation on transient occurrence suggests that the leading edge of a coronal mass ejection (CME), where transient signatures are detected, disrupts the heliospheric <span class="hlt">current</span> <span class="hlt">sheet</span> but that the <span class="hlt">sheet</span> re-forms between the trailing legs of the CME. In this way the global structure of the heliosphere, reflected both in the source surface maps and in the interplanetary sector structure, can be maintained even when the CME occurrence rate is high.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20110015845','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20110015845"><span>Effect of Inductive Coil Geometry and <span class="hlt">Current</span> <span class="hlt">Sheet</span> Trajectory of a Conical Theta Pinch Pulsed Inductive Plasma Accelerator</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hallock, Ashley K.; Polzin, Kurt A.; Bonds, Kevin W.; Emsellem, Gregory D.</p> <p>2011-01-01</p> <p>Results are presented demonstrating the e ect of inductive coil geometry and <span class="hlt">current</span> <span class="hlt">sheet</span> trajectory on the exhaust velocity of propellant in conical theta pinch pulsed induc- tive plasma accelerators. The electromagnetic coupling between the inductive coil of the accelerator and a plasma <span class="hlt">current</span> <span class="hlt">sheet</span> is simulated, substituting a conical copper frustum for the plasma. The variation of system inductance as a function of plasma position is obtained by displacing the simulated <span class="hlt">current</span> <span class="hlt">sheet</span> from the coil while measuring the total inductance of the coil. Four coils of differing geometries were employed, and the total inductance of each coil was measured as a function of the axial displacement of two sep- arate copper frusta both having the same cone angle and length as the coil but with one compressed to a smaller size relative to the coil. The measured relationship between total coil inductance and <span class="hlt">current</span> <span class="hlt">sheet</span> position closes a dynamical circuit model that is used to calculate the resulting <span class="hlt">current</span> <span class="hlt">sheet</span> velocity for various coil and <span class="hlt">current</span> <span class="hlt">sheet</span> con gura- tions. The results of this model, which neglects the pinching contribution to thrust, radial propellant con nement, and plume divergence, indicate that in a conical theta pinch ge- ometry <span class="hlt">current</span> <span class="hlt">sheet</span> pinching is detrimental to thruster performance, reducing the kinetic energy of the exhausting propellant by up to 50% (at the upper bound for the parameter range of the study). The decrease in exhaust velocity was larger for coils and simulated <span class="hlt">current</span> <span class="hlt">sheets</span> of smaller half cone angles. An upper bound for the pinching contribution to thrust is estimated for typical operating parameters. Measurements of coil inductance for three di erent <span class="hlt">current</span> <span class="hlt">sheet</span> pinching conditions are used to estimate the magnetic pressure as a function of <span class="hlt">current</span> <span class="hlt">sheet</span> radial compression. The gas-dynamic contribution to axial acceleration is also estimated and shown to not compensate for the decrease in axial electromagnetic acceleration</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22663347-coronal-heating-topology-interplay-current-sheets-magnetic-field-lines','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22663347-coronal-heating-topology-interplay-current-sheets-magnetic-field-lines"><span>Coronal Heating Topology: The Interplay of <span class="hlt">Current</span> <span class="hlt">Sheets</span> and Magnetic Field Lines</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Rappazzo, A. F.; Velli, M.; Matthaeus, W. H.</p> <p>2017-07-20</p> <p>The magnetic topology and field line random walk (FLRW) properties of a nanoflare-heated and magnetically confined corona are investigated in the reduced magnetohydrodynamic regime. Field lines originating from <span class="hlt">current</span> <span class="hlt">sheets</span> form coherent structures, called <span class="hlt">current</span> <span class="hlt">sheet</span> connected (CSC) regions, which extend around them. CSC FLRW is strongly anisotropic, with preferential diffusion along the <span class="hlt">current</span> sheets’ in-plane length. CSC FLRW properties remain similar to those of the entire ensemble but exhibit enhanced mean square displacements and separations due to the stronger magnetic field intensities in CSC regions. The implications for particle acceleration and heat transport in the solar corona and wind,more » and for solar moss formation are discussed.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JGRA..12211389L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JGRA..12211389L"><span>Electron Cooling and Isotropization during Magnetotail <span class="hlt">Current</span> <span class="hlt">Sheet</span> Thinning: Implications for Parallel Electric Fields</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lu, San; Artemyev, A. V.; Angelopoulos, V.</p> <p>2017-11-01</p> <p>Magnetotail <span class="hlt">current</span> <span class="hlt">sheet</span> thinning is a distinctive feature of substorm growth phase, during which magnetic energy is stored in the magnetospheric lobes. Investigation of charged particle dynamics in such thinning <span class="hlt">current</span> <span class="hlt">sheets</span> is believed to be important for understanding the substorm energy storage and the <span class="hlt">current</span> <span class="hlt">sheet</span> destabilization responsible for substorm expansion phase onset. We use Time History of Events and Macroscale Interactions during Substorms (THEMIS) B and C observations in 2008 and 2009 at 18 - 25 RE to show that during magnetotail <span class="hlt">current</span> <span class="hlt">sheet</span> thinning, the electron temperature decreases (cooling), and the parallel temperature decreases faster than the perpendicular temperature, leading to a decrease of the initially strong electron temperature anisotropy (isotropization). This isotropization cannot be explained by pure adiabatic cooling or by pitch angle scattering. We use test particle simulations to explore the mechanism responsible for the cooling and isotropization. We find that during the thinning, a fast decrease of a parallel electric field (directed toward the Earth) can speed up the electron parallel cooling, causing it to exceed the rate of perpendicular cooling, and thus lead to isotropization, consistent with observation. If the parallel electric field is too small or does not change fast enough, the electron parallel cooling is slower than the perpendicular cooling, so the parallel electron anisotropy grows, contrary to observation. The same isotropization can also be accomplished by an increasing parallel electric field directed toward the equatorial plane. Our study reveals the existence of a large-scale parallel electric field, which plays an important role in magnetotail particle dynamics during the <span class="hlt">current</span> <span class="hlt">sheet</span> thinning process.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li class="active"><span>7</span></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_7 --> <div id="page_8" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li class="active"><span>8</span></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="141"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20120009826','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20120009826"><span>Kinetic Simulations of <span class="hlt">Current-Sheet</span> Formation and Reconnection at a Magnetic X Line</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Black, C.; Antiochos, S. K.; Hesse, M.; Karpen, J. T.; DeVore, C. R.; Kuznetsova, M. M.; Zenitani, S.</p> <p>2011-01-01</p> <p>The integration of kinetic effects into macroscopic numerical models is <span class="hlt">currently</span> of great interest to the plasma physics community, particularly in the context of magnetic reconnection. We are examining the formation and reconnection of <span class="hlt">current</span> <span class="hlt">sheets</span> in a simple, two-dimensional X-line configuration using high resolution particle-in-cell (PIC) simulations. The initial potential magnetic field is perturbed by thermal pressure introduced into the particle distribution far from the X line. The relaxation of this added stress leads to the development of a <span class="hlt">current</span> <span class="hlt">sheet</span>, which reconnects for imposed stress of sufficient strength. We compare the evolution and final state of our PIC simulations with magnetohydrodynamic simulations assuming both uniform and localized resistivities, and with force-free magnetic-field equilibria in which the amount of reconnect ion across the X line can be constrained to be zero (ideal evolution) or optimal (minimum final magnetic energy). We will discuss implications of our results for reconnection onset and cessation at kinetic scales in dynamically formed <span class="hlt">current</span> <span class="hlt">sheets</span>, such as those occurring in the terrestrial magnetotail and solar corona.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20050160223&hterms=post+event&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dpost%2Bevent','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20050160223&hterms=post+event&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dpost%2Bevent"><span>Dynamical and Physical Properties of a Post-Coronal Mass Ejection <span class="hlt">Current</span> <span class="hlt">Sheet</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Ko, Yuan-Kuen; Raymond, John C.; Lin, Jun; Lawrence, Gareth; Li, Jing; Fludra, Andrzej</p> <p>2003-01-01</p> <p>In the eruptive process of the Kopp-Pneuman type, the closed magnetic field is stretched by the eruption so much that it is usually believed to be " open " to infinity. Formation of the <span class="hlt">current</span> <span class="hlt">sheet</span> in such a configuration makes it possible for the energy in the coronal magnetic field to quickly convert into thermal and kinetic energies and cause significant observational consequences, such as growing postflare/CME loop system in the corona, separating bright flare ribbons in the chromosphere, and fast ejections of the plasma and the magnetic flux. An eruption on 2002 January 8 provides us a good opportunity to look into these observational signatures of and place constraints on the theories of eruptions. The event started with the expansion of a magnetic arcade over an active region, developed into a coronal mass ejection (CME), and left some thin streamer-like structures with successively growing loop systems beneath them. The plasma outflow and the highly ionized states of the plasma inside these streamer-like structures, as well as the growing loops beneath them, lead us to conclude that these structures are associated with a magnetic reconnection site, namely, the <span class="hlt">current</span> <span class="hlt">sheet</span>, of this eruptive process. We combine the data from the Ultraviolet Coronagraph Spectrometer, Large Angle and Spectrometric Coronagraph Experiment, EUV Imaging Telescope, and Coronal Diagnostic Spectrometer on board the Solar and Heliospheric Observatory, as well is from the Mauna Loa Solar Observatory Mark IV K-coronameter, to investigate the morphological and dynamical properties of this event, as well as the physical properties of the <span class="hlt">current</span> <span class="hlt">sheet</span>. The velocity and acceleration of the CME reached up to 1800 km/s and 1 km/sq s, respectively. The acceleration is found to occur mainly at the lower corona (<2.76 Solar Radius). The post-CME loop systems showed behaviors of both postflare loops (upward motion with decreasing speed) and soft X-ray giant arches (upward motion with constant</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19900043484&hterms=stochastic+inversion&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dstochastic%2Binversion','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19900043484&hterms=stochastic+inversion&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dstochastic%2Binversion"><span>Ion precipitation from the inner plasma <span class="hlt">sheet</span> due to stochastic diffusion</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Zelenyi, L.; Galeev, A.; Kennel, C. F.</p> <p>1990-01-01</p> <p>Plasma <span class="hlt">sheet</span> ions do not conserve their first adiabatic invariant when the magnetic field is appreciably <span class="hlt">tail</span>-like. They do conserve a different adiabatic invariant but only to linear, rather than exponential, accuracy in the appropriate small parameter. Thus significant stochastic diffusion can occur for particles crossing the separatrix dividing the segments of orbits on which the particles cross and do not cross the <span class="hlt">tail</span> midplane. Such ions can escape the plasma <span class="hlt">sheet</span> and precipitate into the atmosphere. Stochastic scattering is strongest from those field lines where the ion's Larmor period in the normal component of the neutral <span class="hlt">sheet</span> magnetic field approximately equals its bounce period. By comparing the rates of stochastic ion loss and convection in the <span class="hlt">tail</span>, it is possible to estimate the location and thickness of the inner edge of the ion plasma <span class="hlt">sheet</span> created by stochastic ion loss. Ions of different masses precipitate into the atmosphere at slightly different locations. Since wave particle interactions are not needed, this precipitation will always occur and should be particularly evident during quiet geomagnetic conditions, when it is less likely to be masked by other precipitation mechanisms.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003EAEJA....13008H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003EAEJA....13008H"><span>Glaciological constraints on <span class="hlt">current</span> ice mass changes from modelling the ice <span class="hlt">sheets</span> over the glacial cycles</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Huybrechts, P.</p> <p>2003-04-01</p> <p>The evolution of continental ice <span class="hlt">sheets</span> introduces a long time scale in the climate system. Large ice <span class="hlt">sheets</span> have a memory of millenia, hence the present-day ice <span class="hlt">sheets</span> of Greenland and Antarctica are still adjusting to climatic variations extending back to the last glacial period. This trend is separate from the direct response to mass-balance changes on decadal time scales and needs to be correctly accounted for when assessing <span class="hlt">current</span> and future contributions to sea level. One way to obtain estimates of <span class="hlt">current</span> ice mass changes is to model the past history of the ice <span class="hlt">sheets</span> and their underlying beds over the glacial cycles. Such calculations assist to distinguish between the longer-term ice-dynamic evolution and short-term mass-balance changes when interpreting altimetry data, and are helpful to isolate the effects of postglacial rebound from gravity and altimetry trends. The presentation will discuss results obtained from 3-D thermomechanical ice-<span class="hlt">sheet</span>/lithosphere/bedrock models applied to the Antarctic and Greenland ice <span class="hlt">sheets</span>. The simulations are forced by time-dependent boundary conditions derived from sediment and ice core records and are constrained by geomorphological and glacial-geological data of past ice <span class="hlt">sheet</span> and sea-level stands. <span class="hlt">Current</span> simulations suggest that the Greenland ice <span class="hlt">sheet</span> is close to balance, while the Antarctic ice <span class="hlt">sheet</span> is still losing mass, mainly due to incomplete grounding-line retreat of the West Antarctic ice <span class="hlt">sheet</span> since the LGM. The results indicate that altimetry trends are likely dominated by ice thickness changes but that the gravitational signal mainly reflects postglacial rebound.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016APS..DPPC10099N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016APS..DPPC10099N"><span>Plasmoid formation in the elongated <span class="hlt">current</span> <span class="hlt">sheet</span> during transient CHI on HIST</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nagata, Masayoshi; Fujita, Akihiro; Matsui, Takahiro; Kikuchi, Yusuke; Fukumoto, Naoyuki; Kanki, Takashi</p> <p>2016-10-01</p> <p>The Transient-Coaxial Helicity Injection (T-CHI) is a promising candidate for the non-inductive plasma start-up on Spherical Torus (ST). The problem of the flux closure in the T-CHI is important and related to understand the physics of fast magnetic reconnection. The recent MHD simulation (F. Ebrahimi and R. Raman, Phys. Rev. Lett. 114, 205003 (2015)) on T-CHI for NSTX predicts the formation and breakup of an elongated Sweet-Parker (S-P) <span class="hlt">current</span> <span class="hlt">sheet</span> and a transient to plasmoid instability. According to this simulation, the reconnection rate based on the plasmoid instability is faster than that by S-P model and becomes nearly independent of the Lundquist number S. In this meeting, we will present that the formation of multiple X-points and plasmoids has been observed in T-CHI start-up plasmas on HIST. The stronger external guide (toroidal) magnetic field makes plasma less compressible, leading to slower reconnection time and longer <span class="hlt">current</span> <span class="hlt">sheet</span>. The experimental observation shows that 2/3 plasmoids are generated in the elongated <span class="hlt">current</span> <span class="hlt">sheet</span> with the narrow width comparable to the ion skin depth or the ion sound gyro-radius. The small plasmoids develop to a large-scale flux structure due to a <span class="hlt">current</span> inward diffusion during the decay phase.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002EGSGA..27.5116M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002EGSGA..27.5116M"><span>Cluster Observations of <span class="hlt">Currents</span> In The Plasma <span class="hlt">Sheet</span> During Substorm Expansions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>McPherron, R. L.; Kivelson, M. G.; Khurana, K.; Balogh, A.; Conners, M.; Creutzberg, F.; Moldwin, M.; Rostoker, G.; Russell, C. T.</p> <p></p> <p>From 00 to 12 UT on August 15, 2001 the Cluster spacecraft passed through the plasma <span class="hlt">sheet</span> at 0100 lt and distance 18 Re. During this passage three substorms with multiple onsets were observed in the magnetic field and plasma. The North American ground sector was well located to provide the context and timing of these substorms. We find that each substorm was initially associated with strong Earthward directed field-aligned <span class="hlt">current</span>. The first substorm occurred when the Cluster array was at the boundary of the plasma <span class="hlt">sheet</span>. The effects of the substorm appear at Cluster in associ- ation with an intensification of the expansion into the morning sector and are initiated by a wave of plasma <span class="hlt">sheet</span> thickening followed by vertical oscillations of the plasma <span class="hlt">sheet</span> boundary. The third substorm occurred with Cluster at the neutral <span class="hlt">sheet</span>. It began with a transient pulse of southward Bz followed by a burst of tailward flow. Subse- quently a sequence of bursts of Earthward flow cause stepwise dipolarization of the local magnetic field. Our goal is to present a coherent three-dimensional representa- tion of the Cluster observations for each of these various substorms.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22218623-reconnection-three-dimensional-magnetic-null-points-effect-current-sheet-asymmetry','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22218623-reconnection-three-dimensional-magnetic-null-points-effect-current-sheet-asymmetry"><span>Reconnection at three dimensional magnetic null points: Effect of <span class="hlt">current</span> <span class="hlt">sheet</span> asymmetry</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Wyper, P. F.; Jain, Rekha</p> <p>2013-05-15</p> <p>Asymmetric <span class="hlt">current</span> <span class="hlt">sheets</span> are likely to be prevalent in both astrophysical and laboratory plasmas with complex three dimensional (3D) magnetic topologies. This work presents kinematic analytical models for spine and fan reconnection at a radially symmetric 3D null (i.e., a null where the eigenvalues associated with the fan plane are equal) with asymmetric <span class="hlt">current</span> <span class="hlt">sheets</span>. Asymmetric fan reconnection is characterized by an asymmetric reconnection of flux past each spine line and a bulk flow of plasma across the null point. In contrast, asymmetric spine reconnection is characterized by the reconnection of an equal quantity of flux across the fan planemore » in both directions. The higher modes of spine reconnection also include localized wedges of vortical flux transport in each half of the fan. In this situation, two definitions for reconnection rate become appropriate: a local reconnection rate quantifying how much flux is genuinely reconnected across the fan plane and a global rate associated with the net flux driven across each semi-plane. Through a scaling analysis, it is shown that when the ohmic dissipation in the layer is assumed to be constant, the increase in the local rate bleeds from the global rate as the <span class="hlt">sheet</span> deformation is increased. Both models suggest that asymmetry in the <span class="hlt">current</span> <span class="hlt">sheet</span> dimensions will have a profound effect on the reconnection rate and manner of flux transport in reconnection involving 3D nulls.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1334747-laboratory-observation-resistive-electron-tearing-two-fluid-reconnecting-current-sheet','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1334747-laboratory-observation-resistive-electron-tearing-two-fluid-reconnecting-current-sheet"><span>Laboratory observation of resistive electron tearing in a two-fluid reconnecting <span class="hlt">current</span> <span class="hlt">sheet</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Jara-Almonte, Jonathan; Ji, Hantao; Yamada, Masaaki; ...</p> <p>2016-08-25</p> <p>The spontaneous formation of plasmoids via the resistive electron tearing of a reconnecting <span class="hlt">current</span> <span class="hlt">sheet</span> is observed in the laboratory. These experiments are performed during driven, antiparallel reconnection in the two-fluid regime within the Magnetic Reconnection Experiment. It is found that plasmoids are present even at a very low Lundquist number, and the number of plasmoids scales with both the <span class="hlt">current</span> <span class="hlt">sheet</span> aspect ratio and the Lundquist number. Furthermore, the reconnection electric field increases when plasmoids are formed, leading to an enhanced reconnection rate.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..17..242X','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..17..242X"><span>A Statistical Model of the Magnetotail Neutral <span class="hlt">Sheet</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Xiao, Sudong; Zhang, Tielong; Baumjohann, Wolfgang; Nakamura, Rumi; Ge, Yasong; Du, Aimin; Wang, Guoqiang; Lu, Quanming</p> <p>2015-04-01</p> <p>The neutral <span class="hlt">sheet</span> of the magnetotail is characterized by weak magnetic field, strong cross <span class="hlt">tail</span> <span class="hlt">current</span>, and a reversal of the magnetic field direction across it. The dynamics of the earth's magnetosphere is greatly influenced by physical processes that occur near the neutral <span class="hlt">sheet</span>. However, the exact position of the neutral <span class="hlt">sheet</span> is variable in time. It is therefore essential to have a reliable estimate of the average position of the neutral <span class="hlt">sheet</span>. Magnetic field data from ten years of Cluster, nineteen years of Geotail, four years of TC 1, and seven years of THEMIS observations have been incorporated to obtain a model of the magnetotail neutral <span class="hlt">sheet</span>. All data in aberrated GSM (Geocentric Solar Magnetospheric) coordinate system are normalized to the same solar wind pressure condition. The shape and position of the neutral <span class="hlt">sheet</span>, illustrated directly by the separator of positive and negative Bx on the YZ cross sections, are fitted with a displaced ellipse model. It is consistent with previous studies that the neutral <span class="hlt">sheet</span> becomes curvier in the YZ cross section when the dipole tilt increases, yet our model shows the curviest neutral <span class="hlt">sheet</span> compared with previous models. The new model reveals a hinging distance very close to 10 RE at a reference solar wind dynamic pressure of 2 nPa. We find that the earth dipole tilt angle not only affects the neutral <span class="hlt">sheet</span> configuration in the YZ cross section but also in the XZ cross section. The neutral <span class="hlt">sheet</span> becomes more tilting in the XZ cross section when the dipole tilt increases. The effect of an interplanetary magnetic field (IMF) penetration is studied, and an IMF By-related twisting of about 3° is found. Anticlockwise twisting of the neutral <span class="hlt">sheet</span> is observed, looking along the downtail direction, for a positive IMF By, and clockwise twisting of the neutral <span class="hlt">sheet</span> for a negative IMF By.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19850021595','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19850021595"><span>The influence of the heliospheric <span class="hlt">current</span> <span class="hlt">sheet</span> and angular separation on flare accelerated solar wind</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Henning, H. M.; Scherrer, P. H.; Hoeksema, J. T.</p> <p>1985-01-01</p> <p>A complete set of major flares was used to investigate the effect of the heliospheric <span class="hlt">current</span> <span class="hlt">sheet</span> on the magnitude of the flare associated disturbance measured at Earth. It was also found that the angular separation tended to result in a smaller disturbance. Thirdly, it was determined that flares tend to occur near the heliospheric <span class="hlt">current</span> <span class="hlt">sheet</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22663076-multiple-current-sheet-systems-outer-heliosphere-energy-release-turbulence','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22663076-multiple-current-sheet-systems-outer-heliosphere-energy-release-turbulence"><span>MULTIPLE <span class="hlt">CURRENT</span> <span class="hlt">SHEET</span> SYSTEMS IN THE OUTER HELIOSPHERE: ENERGY RELEASE AND TURBULENCE</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Burgess, D.; Gingell, P. W.; Matteini, L.</p> <p>2016-05-01</p> <p>In the outer heliosphere, beyond the solar wind termination shock, it is expected that the warped heliospheric <span class="hlt">current</span> <span class="hlt">sheet</span> forms a region of closely packed, multiple, thin <span class="hlt">current</span> <span class="hlt">sheets</span>. Such a system may be subject to the ion-kinetic tearing instability, and hence may generate magnetic islands and hot populations of ions associated with magnetic reconnection. Reconnection processes in this environment have important implications for local particle transport, and for particle acceleration at reconnection sites and in turbulence. We study this complex environment by means of three-dimensional hybrid simulations over long timescales, in order to capture the evolution from linear growthmore » of the tearing instability to a fully developed turbulent state at late times. The final state develops from the highly ordered initial state via both forward and inverse cascades. Component and spectral anisotropy in the magnetic fluctuations is present when a guide field is included. The inclusion of a population of newborn interstellar pickup protons does not strongly affect these results. Finally, we conclude that reconnection between multiple <span class="hlt">current</span> <span class="hlt">sheets</span> can act as an important source of turbulence in the outer heliosphere, with implications for energetic particle acceleration and propagation.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19870036227&hterms=1085&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3D%2526%25231085','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19870036227&hterms=1085&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3D%2526%25231085"><span>The structure of a cometary type I <span class="hlt">tail</span> - Ground-based and ICE observations of P/Giacobini-Zinner</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Slavin, J. A.; Goldberg, B. A.; Smith, E. J.; Mccomas, D. J.; Bame, S. J.</p> <p>1986-01-01</p> <p>Comparison of ground-based and in situ observations of P/Giacobini-Zinner are used to investigate the morphology of a type I cometary <span class="hlt">tail</span>. ICE magnetic field and plasma measurements show a well-defined cometary magnetotail composed of two magnetic lobes in pressure equilibrium with a central plasma <span class="hlt">sheet</span>. A dependence of ion <span class="hlt">tail</span> width on IMF direction is found which strongly suggests that the classical type I ion <span class="hlt">tails</span> observed on the ground consist predominantly of emissions from the slab-shaped plasma <span class="hlt">sheet</span> separating the magnetic lobes. The width of the G-Z magnetotail is determined to be 9.8 (+ or - 0.5) x 10 to the 3rd km with a quasi-circular cross section. The results of this study also indicate that some of the dynamical thinnings and thickenings observed in long type I <span class="hlt">tails</span> may be caused by IMF variations changing the angle with which the plasma <span class="hlt">sheet</span> is viewed at earth.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20150007928','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20150007928"><span>A Tailward Moving <span class="hlt">Current</span> <span class="hlt">Sheet</span> Normal Magnetic Field Front Followed by an Earthward Moving Dipolarization Front</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hwang, K.-J.; Goldstein, M. L.; Moore, T. E.; Walsh, B. M.; Baishev, D. G.; Moiseyev, A. V.; Shevtsov, B. M.; Yumoto, K.</p> <p>2014-01-01</p> <p>A case study is presented using measurements from the Cluster spacecraft and ground-based magnetometers that show a substorm onset propagating from the inner to outer plasma <span class="hlt">sheet</span>. On 3 October 2005, Cluster, traversing an ion-scale <span class="hlt">current</span> <span class="hlt">sheet</span> at the near-Earth plasma <span class="hlt">sheet</span>, detected a sudden enhancement of Bz, which was immediately followed by a series of flux rope structures. Both the local Bz enhancement and flux ropes propagated tailward. Approximately 5 min later, another Bz enhancement, followed by a large density decrease, was observed to rapidly propagate earthward. Between the two Bz enhancements, a significant removal of magnetic flux occurred, possibly resulting from the tailward moving Bz enhancement and flux ropes. In our scenario, this flux removal caused the magnetotail to be globally stretched so that the thinnest <span class="hlt">sheet</span> formed tailward of Cluster. The thinned <span class="hlt">current</span> <span class="hlt">sheet</span> facilitated magnetic reconnection that quickly evolved from plasma <span class="hlt">sheet</span> to lobe and generated the later earthward moving dipolarization front (DF) followed by a reduction in density and entropy. Ground magnetograms located near the meridian of Cluster's magnetic foot points show two-step bay enhancements. The positive bay associated with the first Bz enhancement indicates that the substorm onset signatures propagated from the inner to the outer plasma <span class="hlt">sheet</span>, consistent with the Cluster observation. The more intense bay features associated with the later DF are consistent with the earthward motion of the front. The event suggests that <span class="hlt">current</span> disruption signatures that originated in the near-Earth <span class="hlt">current</span> <span class="hlt">sheet</span> propagated tailward, triggering or facilitating midtail reconnection, thereby preconditioning the magnetosphere for a later strong substorm enhancement.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006GeoRL..3319102D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006GeoRL..3319102D"><span>Detection of oppositely directed reconnection jets in a solar wind <span class="hlt">current</span> <span class="hlt">sheet</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Davis, M. S.; Phan, T. D.; Gosling, J. T.; Skoug, R. M.</p> <p>2006-10-01</p> <p>We report the first two-spacecraft (Wind and ACE) detection of oppositely directed plasma jets within a bifurcated <span class="hlt">current</span> <span class="hlt">sheet</span> in the solar wind. The event occurred on January 3, 2003 and provides further direct evidence that such jets result from reconnection. The magnetic shear across the bifurcated <span class="hlt">current</span> <span class="hlt">sheet</span> at both Wind and ACE was ~150°, indicating that the magnetic shear must have been the same at the reconnection site located between the two spacecraft. These observations thus provide strong evidence for component merging with a guide field ~ 30% of the antiparallel field. The dimensionless reconnection rate based on the measured inflow was 0.03, implying fast reconnection.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018PlPhR..44..424D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018PlPhR..44..424D"><span>Time Evolution of the Macroscopic Characteristics of a Thin <span class="hlt">Current</span> <span class="hlt">Sheet</span> in the Course of Its Formation in the Earth's Magnetotail</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Domrin, V. I.; Malova, H. V.; Popov, V. Yu.</p> <p>2018-04-01</p> <p>A numerical model is developed that allows tracing the time evolution of a <span class="hlt">current</span> <span class="hlt">sheet</span> from a relatively thick <span class="hlt">current</span> configuration with isotropic distributions of the pressure and temperature in an extremely thin <span class="hlt">current</span> <span class="hlt">sheet</span>, which plays a key role in geomagnetic processes. Such a configuration is observed in the Earth's magnetotail in the stage preceding a large-scale geomagnetic disturbance (substorm). Thin <span class="hlt">current</span> <span class="hlt">sheets</span> are reservoirs of the free energy released during geomagnetic disturbances. The time evolution of the components of the pressure tensor caused by changes in the structure of the <span class="hlt">current</span> <span class="hlt">sheet</span> is investigated. It is shown that the pressure tensor in the <span class="hlt">current</span> <span class="hlt">sheet</span> evolves in two stages. In the first stage, a <span class="hlt">current</span> <span class="hlt">sheet</span> with a thickness of eight to ten proton Larmor radii forms. This stage is characterized by the plasma drift toward the <span class="hlt">current</span> <span class="hlt">sheet</span> and the Earth and can be described in terms of the Chu-Goldberger-Low approximation. In the second stage, an extremely thin <span class="hlt">current</span> <span class="hlt">sheet</span> with an anisotropic plasma pressure tensor forms, due to which the system is maintained in an equilibrium state. Estimates of the characteristic time of the system evolution agree with available experimental data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22661418-evidence-quasi-adiabatic-motion-charged-particles-strong-current-sheets-solar-wind','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22661418-evidence-quasi-adiabatic-motion-charged-particles-strong-current-sheets-solar-wind"><span>EVIDENCE FOR QUASI-ADIABATIC MOTION OF CHARGED PARTICLES IN STRONG <span class="hlt">CURRENT</span> <span class="hlt">SHEETS</span> IN THE SOLAR WIND</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Malova, H. V.; Popov, V. Yu.; Grigorenko, E. E.</p> <p></p> <p>We investigate quasi-adiabatic dynamics of charged particles in strong <span class="hlt">current</span> <span class="hlt">sheets</span> (SCSs) in the solar wind, including the heliospheric <span class="hlt">current</span> <span class="hlt">sheet</span> (HCS), both theoretically and observationally. A self-consistent hybrid model of an SCS is developed in which ion dynamics is described at the quasi-adiabatic approximation, while the electrons are assumed to be magnetized, and their motion is described in the guiding center approximation. The model shows that the SCS profile is determined by the relative contribution of two <span class="hlt">currents</span>: (i) the <span class="hlt">current</span> supported by demagnetized protons that move along open quasi-adiabatic orbits, and (ii) the electron drift <span class="hlt">current</span>. The simplestmore » modeled SCS is found to be a multi-layered structure that consists of a thin <span class="hlt">current</span> <span class="hlt">sheet</span> embedded into a much thicker analog of a plasma <span class="hlt">sheet</span>. This result is in good agreement with observations of SCSs at ∼1 au. The analysis of fine structure of different SCSs, including the HCS, shows that an SCS represents a narrow <span class="hlt">current</span> layer (with a thickness of ∼10{sup 4} km) embedded into a wider region of about 10{sup 5} km, independently of the SCS origin. Therefore, multi-scale structuring is very likely an intrinsic feature of SCSs in the solar wind.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006AGUFMSM43C..02D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006AGUFMSM43C..02D"><span>Detection of oppositely directed reconnection jets in a solar wind <span class="hlt">current</span> <span class="hlt">sheet</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Davis, M. S.; Phan, T. D.; Gosling, J. T.; Skoug, R. M.</p> <p>2006-12-01</p> <p>We report the first two-spacecraft (Wind and ACE) detection of oppositely directed plasma jets within a bifurcated <span class="hlt">current</span> <span class="hlt">sheet</span> in the solar wind. The event occurred on January 3, 2003 and provides further direct evidence that such jets result from reconnection. The magnetic shear across the bifurcated <span class="hlt">current</span> <span class="hlt">sheet</span> at both Wind and ACE was approximately 150 degrees, indicating that the magnetic shear must have been the same at the reconnection site located between the two spacecraft. These observations thus provide strong evidence for component merging with a guide field approximately 30% of the antiparallel field. The dimensionless reconnection rate based on the measured inflow was 0.03, implying fast reconnection.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19930004289','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19930004289"><span>The 3-D description of vertical <span class="hlt">current</span> <span class="hlt">sheets</span> with application to solar flares</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Fontenla, Juan M.; Davis, J. M.</p> <p>1991-01-01</p> <p>Following a brief review of the processes which have been suggested for explaining the occurrence of solar flares we suggest a new scenario which builds on the achievements of the previous suggestion that the <span class="hlt">current</span> <span class="hlt">sheets</span>, which develop naturally in 3-D cases with gravity from impacting independent magnetic structures (i.e., approaching <span class="hlt">current</span> systems), do not consist of horizontal <span class="hlt">currents</span> but are instead predominantly vertical <span class="hlt">current</span> systems. This suggestion is based on the fact that as the subphotospheric sources of the magnetic field displace the upper photosphere and lower chromosphere regions, where plasma beta is near unity, will experience predominantly horizontal mass motions which will lead to a distorted 3-D configurations of the magnetic field having stored free energy. In our scenario, a vertically flowing <span class="hlt">current</span> <span class="hlt">sheet</span> separates the plasma regions associated with either of the subphotospheric sources. This reflects the balanced tension of the two stressed fields which twist around each other. This leads naturally to a metastable or unstable situation as the twisted field emerges into a low beta region where vertical motions are not inhibited by gravity. In our flare scenario the impulsive energy release occurs, initially, not by reconnection but mainly by the rapid change of the magnetic field which has become unstable. During the impulsive phase the field lines contort in such way as to realign the electric <span class="hlt">current</span> <span class="hlt">sheet</span> into a minimum energy horizontal flow. This contortion produces very large electric fields which will accelerate particles. As the <span class="hlt">current</span> evolves to a horizontal configuration the magnetic field expands vertically, which can be accompanied by eruptions of material. The instability of a horizontal <span class="hlt">current</span> is well known and causes the magnetic field to undergo a rapid outward expansion. In our scenario, fast reconnection is not necessary to trigger the flare, however, slow reconnection would occur continuously in the <span class="hlt">current</span> layer</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19930004962','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19930004962"><span><span class="hlt">Current</span> status of liquid <span class="hlt">sheet</span> radiator research</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Chubb, Donald L.; Calfo, Frederick D.; Mcmaster, Matthew S.</p> <p>1993-01-01</p> <p>Initial research on the external flow, low mass liquid <span class="hlt">sheet</span> radiator (LSR), has been concentrated on understanding its fluid mechanics. The surface tension forces acting at the edges of the <span class="hlt">sheet</span> produce a triangular planform for the radiating surface of width, W, and length, L. It has been experimentally verified that (exp L)/W agrees with the theoretical result, L/W = (We/8)exp 1/2, where We is the Weber number. Instability can cause holes to form in regions of large curvature such as where the edge cylinders join the <span class="hlt">sheet</span> of thickness, tau. The W/tau limit that will cause hole formation with subsequent destruction of the <span class="hlt">sheet</span> has yet to be reached experimentally. Although experimental measurements of <span class="hlt">sheet</span> emissivity have not yet been performed because of limited program scope, calculations of the emissivity and <span class="hlt">sheet</span> lifetime is determined by evaporation losses were made for two silicon based oils; Dow Corning 705 and Me(sub 2). Emissivities greater than 0.75 are calculated for tau greater than or equal to 200 microns for both oils. Lifetimes for Me(sub 2) are much longer than lifetimes for 705. Therefore, Me(sub 2) is the more attractive working fluid for higher temperatures (T greater than or equal to 400 K).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018FlDyR..50a1402M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018FlDyR..50a1402M"><span>Large scale EMF in <span class="hlt">current</span> <span class="hlt">sheets</span> induced by tearing modes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mizerski, Krzysztof A.</p> <p>2018-02-01</p> <p>An extension of the analysis of resistive instabilities of a <span class="hlt">sheet</span> pinch from a famous work by Furth et al (1963 Phys. Fluids 6 459) is presented here, to study the mean electromotive force (EMF) generated by the developing instability. In a Cartesian configuration and in the presence of a <span class="hlt">current</span> <span class="hlt">sheet</span> first the boundary layer technique is used to obtain global, matched asymptotic solutions for the velocity and magnetic field and then the solutions are used to calculate the large-scale EMF in the system. It is reported, that in the bulk the curl of the mean EMF is linear in {{j}}0\\cdot {{B}}0, a simple pseudo-scalar quantity constructed from the large-scale quantities.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li class="active"><span>8</span></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_8 --> <div id="page_9" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li class="active"><span>9</span></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="161"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22663852-observations-formation-development-structure-current-sheet-eruptive-solar-flare','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22663852-observations-formation-development-structure-current-sheet-eruptive-solar-flare"><span>Observations of the Formation, Development, and Structure of a <span class="hlt">Current</span> <span class="hlt">Sheet</span> in an Eruptive Solar Flare</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Seaton, Daniel B.; Darnel, Jonathan M.; Bartz, Allison E., E-mail: daniel.seaton@noaa.gov</p> <p>2017-02-01</p> <p>We present Atmospheric Imaging Assembly observations of a structure we interpret as a <span class="hlt">current</span> <span class="hlt">sheet</span> associated with an X4.9 flare and coronal mass ejection that occurred on 2014 February 25 in NOAA Active Region 11990. We characterize the properties of the <span class="hlt">current</span> <span class="hlt">sheet</span>, finding that the <span class="hlt">sheet</span> remains on the order of a few thousand kilometers thick for much of the duration of the event and that its temperature generally ranged between 8 and 10 MK. We also note the presence of other phenomena believed to be associated with magnetic reconnection in <span class="hlt">current</span> <span class="hlt">sheets</span>, including supra-arcade downflows and shrinking loops.more » We estimate that the rate of reconnection during the event was M{sub A} ≈ 0.004–0.007, a value consistent with model predictions. We conclude with a discussion of the implications of this event for reconnection-based eruption models.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20040129661','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20040129661"><span>Mutual Inductance Problem for a System Consisting of a <span class="hlt">Current</span> <span class="hlt">Sheet</span> and a Thin Metal Plate</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Fulton, J. P.; Wincheski, B.; Nath, S.; Namkung, M.</p> <p>1993-01-01</p> <p>Rapid inspection of aircraft structures for flaws is of vital importance to the commercial and defense aircraft industry. In particular, inspecting thin aluminum structures for flaws is the focus of a large scale R&D effort in the nondestructive evaluation (NDE) community. Traditional eddy <span class="hlt">current</span> methods used today are effective, but require long inspection times. New electromagnetic techniques which monitor the normal component of the magnetic field above a sample due to a <span class="hlt">sheet</span> of <span class="hlt">current</span> as the excitation, seem to be promising. This paper is an attempt to understand and analyze the magnetic field distribution due to a <span class="hlt">current</span> <span class="hlt">sheet</span> above an aluminum test sample. A simple theoretical model, coupled with a two dimensional finite element model (FEM) and experimental data will be presented in the next few sections. A <span class="hlt">current</span> <span class="hlt">sheet</span> above a conducting sample generates eddy <span class="hlt">currents</span> in the material, while a sensor above the <span class="hlt">current</span> <span class="hlt">sheet</span> or in between the two plates monitors the normal component of the magnetic field. A rivet or a surface flaw near a rivet in an aircraft aluminum skin will disturb the magnetic field, which is imaged by the sensor. Initial results showed a strong dependence of the flaw induced normal magnetic field strength on the thickness and conductivity of the <span class="hlt">current-sheet</span> that could not be accounted for by skin depth attenuation alone. It was believed that the eddy <span class="hlt">current</span> imaging method explained the dependence of the thickness and conductivity of the flaw induced normal magnetic field. Further investigation, suggested the complexity associated with the mutual inductance of the system needed to be studied. The next section gives an analytical model to better understand the phenomenon.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19850030808&hterms=Magnetic+energy&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DMagnetic%2Benergy','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19850030808&hterms=Magnetic+energy&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DMagnetic%2Benergy"><span>Driven magnetic reconnection in three dimensions - Energy conversion and field-aligned <span class="hlt">current</span> generation</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Sato, T.; Walker, R. J.; Ashour-Abdalla, M.</p> <p>1984-01-01</p> <p>The energy conversion processes occurring in three-dimensional driven reconnection is analyzed. In particular, the energy conversion processes during localized reconnection in a taillike magnetic configuration are studied. It is found that three-dimensional driven reconnection is a powerful energy converter which transforms magnetic energy into plasma bulk flow and thermal energy. Three-dimensional driven reconnection is an even more powerful energy converter than two-dimensional reconnection, because in the three-dimensional case, plasmas were drawn into the reconnection region from the sides as well as from the top and bottom. Field-aligned <span class="hlt">currents</span> are generated by three-dimensional driven reconnection. The physical mechanism responsible for these <span class="hlt">currents</span> which flow from the <span class="hlt">tail</span> toward the ionosphere on the dawnside of the reconnection region and from the ionosphere toward the <span class="hlt">tail</span> on the duskside is identified. The field-aligned <span class="hlt">currents</span> form as the neutral <span class="hlt">sheet</span> <span class="hlt">current</span> is diverted through the slow shocks which form on the outer edge of the reconnected field lines (outer edge of the plasma <span class="hlt">sheet</span>).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017MS%26E..200a2042B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017MS%26E..200a2042B"><span>Critical study of <span class="hlt">current</span> situation of Vrănicioara <span class="hlt">tailing</span> pond on Cavnicului Valley, risks and consequences</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bud, I.; Duma, S.; Gusat, D.; Pasca, I.; Bud, A.</p> <p>2017-05-01</p> <p>In northern Romania, there are numerous <span class="hlt">tailing</span> ponds, resulting from mining activities that present significant environmental risks. Some of them, including Vrănicioara <span class="hlt">tailing</span> pond, were the subject of technical projects for ecological rehabilitation. Vrănicioara pond is located on the right side of Cavnic Valley, downstream Cavnic town, about 4 kilometers far. It has about 500 m length and is located parallel to the road linking Baia Sprie and Cavnic localities. Chemical and physical stability of the <span class="hlt">tailing</span> pond before rehabilitation interest the research, analysis and conclusions were published in several scientific meetings. In addition, close to the pond at less than 100 m, an open pit has developed, exploiting andesite by mining blast, increasing the risk of physical stability by continuous exposure to vibration. This activity <span class="hlt">currently</span> continues, advancing towards the <span class="hlt">tailing</span> pond body. The critical study addresses the <span class="hlt">current</span> state of Vrănicioara <span class="hlt">Tailing</span> Pond, analysis of some rehabilitation works done incorrectly, analysis of chemical stability that was not a priority during rehabilitation. Research intention is heading to water analysis confirming the existence of acid drainage that was not stopped or at least reduced. The scientific approach is based on the Technical Standards for Waste Deposits, in force in Romania, providing the rules to ensure physical and chemical stability.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19930069264&hterms=disruption&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Ddisruption','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19930069264&hterms=disruption&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Ddisruption"><span>On the energy budget in the <span class="hlt">current</span> disruption region. [of geomagnetic <span class="hlt">tail</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hesse, Michael; Birn, Joachim</p> <p>1993-01-01</p> <p>This study investigates the energy budget in the <span class="hlt">current</span> disruption region of the magnetotail, coincident with a pre-onset thin <span class="hlt">current</span> <span class="hlt">sheet</span>, around substorm onset time using published observational data and theoretical estimates. We find that the <span class="hlt">current</span> disruption/dipolarization process typically requires energy inflow into the primary disruption region. The disruption dipolarization process is therefore endoenergetic, i.e., requires energy input to operate. Therefore we argue that some other simultaneously operating process, possibly a large scale magnetotail instability, is required to provide the necessary energy input into the <span class="hlt">current</span> disruption region.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1980JGR....85.3329J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1980JGR....85.3329J"><span>Modeling Jupiter's <span class="hlt">current</span> disc - Pioneer 10 outbound</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jones, D. E.; Melville, J. G.; Blake, M. L.</p> <p>1980-07-01</p> <p>A model of the magnetic field of the Jovian <span class="hlt">current</span> disk is presented. The model uses Euler functions and the Biot-Savart law applied to a series of concentric, but not necessarily coplanar <span class="hlt">current</span> rings. It was found that the best fit to the Pioneer 10 outbound perturbation magnetic field data is obtained if the <span class="hlt">current</span> disk is twisted, and also bent to tend toward parallelism with the Jovigraphic equator. The inner and outer radii of the disk appear to be about 7 and 150 Jovian radii, respectively; because of the observed <span class="hlt">current</span> disk penetrations, the bent disk also requires a deformation in the form of a bump or wrinkle whose axis tends to exhibit spiraling. Modeling of the azimuthal field shows that it is due to a thin radial <span class="hlt">current</span> <span class="hlt">sheet</span>, but it may actually be due in large part to penetration of a <span class="hlt">tail</span> <span class="hlt">current</span> <span class="hlt">sheet</span> as suggested by Voyager observations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20060009303&hterms=Electric+current&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DElectric%2Bcurrent','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20060009303&hterms=Electric+current&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DElectric%2Bcurrent"><span>Cluster electric <span class="hlt">current</span> density measurements within a magnetic flux rope in the plasma <span class="hlt">sheet</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Slavin, J. A.; Lepping, R. P.; Gjerloev, J.; Goldstein, M. L.; Fairfield, D. H.; Acuna, M. H.; Balogh, A.; Dunlop, M.; Kivelson, M. G.; Khurana, K.</p> <p>2003-01-01</p> <p>On August 22, 2001 all 4 Cluster spacecraft nearly simultaneously penetrated a magnetic flux rope in the <span class="hlt">tail</span>. The flux rope encounter took place in the central plasma <span class="hlt">sheet</span>, Beta(sub i) approx. 1-2, near the leading edge of a bursty bulk flow. The "time-of-flight" of the flux rope across the 4 spacecraft yielded V(sub x) approx. 700 km/s and a diameter of approx.1 R(sub e). The speed at which the flux rope moved over the spacecraft is in close agreement with the Cluster plasma measurements. The magnetic field profiles measured at each spacecraft were first modeled separately using the Lepping-Burlaga force-free flux rope model. The results indicated that the center of the flux rope passed northward (above) s/c 3, but southward (below) of s/c 1, 2 and 4. The peak electric <span class="hlt">currents</span> along the central axis of the flux rope predicted by these single-s/c models were approx.15-19 nA/sq m. The 4-spacecraft Cluster magnetic field measurements provide a second means to determine the electric <span class="hlt">current</span> density without any assumption regarding flux rope structure. The <span class="hlt">current</span> profile determined using the curlometer technique was qualitatively similar to those determined by modeling the individual spacecraft magnetic field observations and yielded a peak <span class="hlt">current</span> density of 17 nA/m2 near the central axis of the rope. However, the curlometer results also showed that the flux rope was not force-free with the component of the <span class="hlt">current</span> density perpendicular to the magnetic field exceeding the parallel component over the forward half of the rope, perhaps due to the pressure gradients generated by the collision of the BBF with the inner magnetosphere. Hence, while the single-spacecraft models are very successful in fitting flux rope magnetic field and <span class="hlt">current</span> variations, they do not provide a stringent test of the force-free condition.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1913077D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1913077D"><span>H+ and O+ dynamics during ultra-low frequency waves in the Earth's magnetotail plasma <span class="hlt">sheet</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>De Spiegeleer, Alexandre; Hamrin, Maria; Pitkänen, Timo; Volwerk, Martin; Mouikis, Christopher; Kistler, Lynn; Nilsson, Hans; Norqvist, Patrik; Andersson, Laila</p> <p>2017-04-01</p> <p>The concentration of ionospheric oxygen (O^+) in the magnetotail plasma <span class="hlt">sheet</span> can be relatively elevated depending on, for instance, the geomagnetic activity as well as the solar cycle. The dynamics of the <span class="hlt">tail</span> plasma <span class="hlt">sheet</span> can be affected by the presence of O+ via for example the generation of instabilities such as the Kelvin-Helmholtz instability. However, the O+ is not always taken into account when studying the dynamics of the <span class="hlt">tail</span> plasma <span class="hlt">sheet</span>. We investigate proton (H^+) and O+ during ultra-low frequency waves (period > 5 min) in the mid-<span class="hlt">tail</span> plasma <span class="hlt">sheet</span> (beyond 10R_E) using Cluster data. We observe that the velocity of O+ can be significantly different from that of H^+. When occuring, this velocity difference always seems to be in the direction parallel to the magnetic field. The parallel velocity of the two species can be observed to be somewhat out of phase, meaning that while one species flows in the parallel direction, the other flows in the anti-parallel direction. Possible causes for such large discrepancies between the dynamics of O+ and H+ are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20010032409&hterms=Russell&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAuthor-Name%26Nf%3DPublication-Date%257CBTWN%2B20000101%2B20001231%26N%3D0%26No%3D20%26Ntt%3DRussell','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20010032409&hterms=Russell&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAuthor-Name%26Nf%3DPublication-Date%257CBTWN%2B20000101%2B20001231%26N%3D0%26No%3D20%26Ntt%3DRussell"><span>Substorms At Jupiter: Galileo Observations of Transient Reconnection in The Near <span class="hlt">Tail</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Russell, C. T.; Khurana, K. K.; Kivelson, M. G.; Huddleston, D. E.</p> <p>2000-01-01</p> <p>The magnetic flux content of the Jovian magnetosphere is set by the internal dynamo, but those magnetic field lines are constantly being loaded by heavy ions at the orbit of lo and dragged inexorably outward by the centrifugal force. Vasyliunas has proposed a steady state reconnecting magnetospheric model that sheds plasma islands of zero net magnetic flux and returns nearly empty flux tubes to the inner magnetosphere. The Galileo observations indicate that beyond 40 Rj the <span class="hlt">current</span> <span class="hlt">sheet</span> begins to tear and beyond 50 Rj on the nightside explosively reconnects as the tearing site reaches the low density lobe region above and below the <span class="hlt">current</span> <span class="hlt">sheet</span>. Small events occur irregularly but on average about every 4 hours and large events about once a day. The magnetic flux reconnected in such events amounts up to about 70,000 Webers/sec and is sufficient to return the outwardly convected magnetic flux to the inner magnetosphere. Since this process releases plasmoids into the jovian <span class="hlt">tail</span>, as do terrestrial substorms; since this process involves explosive reconnection across the <span class="hlt">current</span> <span class="hlt">sheet</span> on the nightside of the planet, as do terrestrial substorms; and since the process is a key in closing the circulation pattern of the magnetic and plasma flux, as it is in terrestrial substorms; we refer to these events as jovian substorms.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018ApJ...854...23B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018ApJ...854...23B"><span>Modeling Solar Energetic Particle Transport near a Wavy Heliospheric <span class="hlt">Current</span> <span class="hlt">Sheet</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Battarbee, Markus; Dalla, Silvia; Marsh, Mike S.</p> <p>2018-02-01</p> <p>Understanding the transport of solar energetic particles (SEPs) from acceleration sites at the Sun into interplanetary space and to the Earth is an important question for forecasting space weather. The interplanetary magnetic field (IMF), with two distinct polarities and a complex structure, governs energetic particle transport and drifts. We analyze for the first time the effect of a wavy heliospheric <span class="hlt">current</span> <span class="hlt">sheet</span> (HCS) on the propagation of SEPs. We inject protons close to the Sun and propagate them by integrating fully 3D trajectories within the inner heliosphere in the presence of weak scattering. We model the HCS position using fits based on neutral lines of magnetic field source surface maps (SSMs). We map 1 au proton crossings, which show efficient transport in longitude via HCS, depending on the location of the injection region with respect to the HCS. For HCS tilt angles around 30°–40°, we find significant qualitative differences between A+ and A‑ configurations of the IMF, with stronger fluences along the HCS in the former case but with a distribution of particles across a wider range of longitudes and latitudes in the latter. We show how a wavy <span class="hlt">current</span> <span class="hlt">sheet</span> leads to longitudinally periodic enhancements in particle fluence. We show that for an A+ IMF configuration, a wavy HCS allows for more proton deceleration than a flat HCS. We find that A‑ IMF configurations result in larger average fluences than A+ IMF configurations, due to a radial drift component at the <span class="hlt">current</span> <span class="hlt">sheet</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19940025621','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19940025621"><span>A study of the formation and dynamics of the Earth's plasma <span class="hlt">sheet</span> using ion composition data</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Lennartsson, O. W.</p> <p>1994-01-01</p> <p>Over two years of data from the Lockheed Plasma Composition Experiment on the ISEE 1 spacecraft, covering ion energies between 100 eV/e and about 16 keV/e, have been analyzed in an attempt to extract new information about three geophysical issues: (1) solar wind penetration of the Earth's magnetic <span class="hlt">tail</span>; (2) relationship between plasma <span class="hlt">sheet</span> and <span class="hlt">tail</span> lobe ion composition; and (3) possible effects of heavy terrestrial ions on plasma <span class="hlt">sheet</span> stability.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/183241-structured-plasma-sheet-thinning-observed-galileo','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/183241-structured-plasma-sheet-thinning-observed-galileo"><span>Structured plasma <span class="hlt">sheet</span> thinning observed by Galileo and 1984-129</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Reeves, G.D.; Belian, R.D.; Fritz, T.A.</p> <p></p> <p>On December 8, 1990, the Galileo spacecraft used the Earth for a gravity assist on its way to Jupiter. Its trajectory was such that is crossed geosynchronous orbit at approximately local midnight between 1900 and 2000 UT. At the same time, spacecraft 1984-129 was also located at geosynchronous orbit near local midnight. Several flux dropout events were observed when the two spacecraft were in the near-Earth plasma <span class="hlt">sheet</span> in the same local time sector. Flux dropout events are associated with plasma <span class="hlt">sheet</span> thinning in the near-Earth <span class="hlt">tail</span> during the growth phase of substorms. This period is unique in that Galileomore » provided a rapid radial profile of the near-Earth plasma <span class="hlt">sheet</span> while 1984-129 provided an azimuthal profile. With measurements from these two spacecraft the authors can distinguish between spatial structures and temporal changes. Their observations confirm that the geosynchronous flux dropout events are consistent with plasma <span class="hlt">sheet</span> thinning which changes the spacecraft`s magnetic connection from the trapping region to the more distant plasma <span class="hlt">sheet</span>. However, for this period, thinning occurred on two spatial and temporal scales. The geosynchronous dropouts were highly localized phenomena of 30 min duration superimposed on a more global reconfiguration of the <span class="hlt">tail</span> lasting approximately 4 hours. 28 refs., 10 figs.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19930083256','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19930083256"><span>Theoretical aerodynamic characteristics of a family of slender wing-<span class="hlt">tail</span>-body combinations</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Lomax, Harvard; Byrd, Paul F</p> <p>1951-01-01</p> <p>The aerodynamic characteristics of an airplane configuration composed of a swept-back, nearly constant chord wing and a triangular <span class="hlt">tail</span> mounted on a cylindrical body are presented. The analysis is based on the assumption that the free-stream Mach number is near unity or that the configuration is slender. The calculations for the <span class="hlt">tail</span> are made on the assumption that the vortex system trailing back from the wing is either a <span class="hlt">sheet</span> lying entirely in the plane of the flat <span class="hlt">tail</span> surface or has completely "rolled up" into two point vortices that lie either in, above, or below the plane of the <span class="hlt">tail</span> surface.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007AGUFMSH53A1069S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007AGUFMSH53A1069S"><span>Conical <span class="hlt">Current</span> <span class="hlt">Sheets</span> in a Source-Surface Model of the Heliosphere</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schulz, M.</p> <p>2007-12-01</p> <p>Different methods of modeling the coronal and heliospheric magnetic field are conveniently visualized and intercompared by applying them to ideally axisymmetric field models. Thus, for example, a dipolar B field with its moment parallel to the Sun's rotation axis leads to a flat heliospheric <span class="hlt">current</span> <span class="hlt">sheet</span>. More general solar B fields (still axisymmetric about the solar rotation axis for simplicity) typically lead to cone-shaped <span class="hlt">current</span> <span class="hlt">sheets</span> beyond the source surface (and presumably also in MHD models). As in the dipolar case [Schulz et al., Solar Phys., 60, 83-104, 1978], such conical <span class="hlt">current</span> <span class="hlt">sheets</span> can be made realistically thin by taking the source surface to be non-spherical in a way that reflects the underlying structure of the Sun's main B field. A source surface that seems to work well in this respect [Schulz, Ann. Geophysicae, 15, 1379-1387, 1997] is a surface of constant F = (1/r)kB, where B is the scalar strength of the Sun's main magnetic field and k (~ 1.4) is a shape parameter. This construction tends to flatten the source surface in regions where B is relatively weak. Thus, for example, the source surface for a dipolar B field is shaped somewhat like a Rugby football, whereas the source surface for an axisymmetric quadrupolar B field is similarly elongated but somewhat flattened (as if stuffed into a cone) at mid-latitudes. A linear combination of co-axial dipolar and quadrupolar B fields generates a somewhat pear-shaped (but still convex) source surface. If the region surrounded by the source surface is regarded as <span class="hlt">current</span>-free, then the source surface itself should be (as nearly as possible) an equipotential surface for the corresponding magnetic scalar potential (expanded, for example, in spherical harmonics). The solar wind should then flow not quite radially, but rather in a straight line along the outward normal to the source surface, and the heliospheric B field should follow a corresponding generalization of Parker's spiral [Levine et al</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20170003265&hterms=layer&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dlayer','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20170003265&hterms=layer&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dlayer"><span>Transient, Small-Scale Field-Aligned <span class="hlt">Currents</span> in the Plasma <span class="hlt">Sheet</span> Boundary Layer During Storm Time Substorms</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Nakamura, R.; Sergeev, V. A.; Baumjohann, W.; Plaschke, F.; Magnes, W.; Fischer, D.; Varsani, A.; Schmid, D.; Nakamura, T. K. M.; Russell, C. T.; <a style="text-decoration: none; " href="javascript:void(0); " onClick="displayelement('author_20170003265'); toggleEditAbsImage('author_20170003265_show'); toggleEditAbsImage('author_20170003265_hide'); "> <img style="display:inline; width:12px; height:12px; " src="images/arrow-up.gif" width="12" height="12" border="0" alt="hide" id="author_20170003265_show"> <img style="width:12px; height:12px; display:none; " src="images/arrow-down.gif" width="12" height="12" border="0" alt="hide" id="author_20170003265_hide"></p> <p>2016-01-01</p> <p>We report on field-aligned <span class="hlt">current</span> observations by the four Magnetospheric Multiscale (MMS) spacecraft near the plasma <span class="hlt">sheet</span> boundary layer (PSBL) during two major substorms on 23 June 2015. Small-scale field-aligned <span class="hlt">currents</span> were found embedded in fluctuating PSBL flux tubes near the Separatrix region. We resolve, for the first time, short-lived earthward (downward) intense field-aligned <span class="hlt">current</span> <span class="hlt">sheets</span> with thicknesses of a few tens of kilometers, which are well below the ion scale, on flux tubes moving equatorward earth ward during outward plasma <span class="hlt">sheet</span> expansion. They coincide with upward field-aligned electron beams with energies of a few hundred eV. These electrons are most likely due to acceleration associated with a reconnection jet or high-energy ion beam-produced disturbances. The observations highlight coupling of multiscale processes in PSBL as a consequence of magnetotail reconnection.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27867235','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27867235"><span>Transient, small-scale field-aligned <span class="hlt">currents</span> in the plasma <span class="hlt">sheet</span> boundary layer during storm time substorms.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Nakamura, R; Sergeev, V A; Baumjohann, W; Plaschke, F; Magnes, W; Fischer, D; Varsani, A; Schmid, D; Nakamura, T K M; Russell, C T; Strangeway, R J; Leinweber, H K; Le, G; Bromund, K R; Pollock, C J; Giles, B L; Dorelli, J C; Gershman, D J; Paterson, W; Avanov, L A; Fuselier, S A; Genestreti, K; Burch, J L; Torbert, R B; Chutter, M; Argall, M R; Anderson, B J; Lindqvist, P-A; Marklund, G T; Khotyaintsev, Y V; Mauk, B H; Cohen, I J; Baker, D N; Jaynes, A N; Ergun, R E; Singer, H J; Slavin, J A; Kepko, E L; Moore, T E; Lavraud, B; Coffey, V; Saito, Y</p> <p>2016-05-28</p> <p>We report on field-aligned <span class="hlt">current</span> observations by the four Magnetospheric Multiscale (MMS) spacecraft near the plasma <span class="hlt">sheet</span> boundary layer (PSBL) during two major substorms on 23 June 2015. Small-scale field-aligned <span class="hlt">currents</span> were found embedded in fluctuating PSBL flux tubes near the separatrix region. We resolve, for the first time, short-lived earthward (downward) intense field-aligned <span class="hlt">current</span> <span class="hlt">sheets</span> with thicknesses of a few tens of kilometers, which are well below the ion scale, on flux tubes moving equatorward/earthward during outward plasma <span class="hlt">sheet</span> expansion. They coincide with upward field-aligned electron beams with energies of a few hundred eV. These electrons are most likely due to acceleration associated with a reconnection jet or high-energy ion beam-produced disturbances. The observations highlight coupling of multiscale processes in PSBL as a consequence of magnetotail reconnection.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSM31A2603M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSM31A2603M"><span>Energization of the Ring <span class="hlt">Current</span> through Convection of Substorm Enhancements of the Plasma <span class="hlt">Sheet</span> Source.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Menz, A.; Kistler, L. M.; Mouikis, C.; Spence, H. E.; Henderson, M. G.; Matsui, H.</p> <p>2017-12-01</p> <p>It has been shown that electric field strength and night-side plasma <span class="hlt">sheet</span> density are the two best predictors of the adiabatic energy gain of the ring <span class="hlt">current</span> during geomagnetic storms (Liemohn and Khazanov, 2005). While H+ dominates the ring <span class="hlt">current</span> during quiet times, O+ can contribute substantially during geomagnetic storms. Substorm activity provides a mechanism to enhance the energy density of O+ in the plasma <span class="hlt">sheet</span> during geomagnetic storms, which is then convected adiabatically into the inner-magnetosphere. Using the Van Allen Probes data in the the plasma <span class="hlt">sheet</span> source region (defined as L>5.5 during storms) and the inner magnetosphere, along with LANL-GEO data to identify substorm injection times, we show that adiabatic convection of O+ enhancements in the source region can explain the observed enhancements in the inner magnetosphere. We use the UNH-IMEF electric field model to calculate drift times from the source region to the inner magnetosphere to test whether enhancements in the inner-magnetosphere can be explained by dipolarization driven enhancements in the plasma <span class="hlt">sheet</span> source hours before.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22472206-current-sheet-plasma-system-controlling-parameter','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22472206-current-sheet-plasma-system-controlling-parameter"><span><span class="hlt">Current</span> <span class="hlt">sheet</span> in plasma as a system with a controlling parameter</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Fridman, Yu. A., E-mail: yulya-fridman@yandex.ru; Chukbar, K. V., E-mail: Chukbar-KV@nrcki.ru</p> <p>2015-08-15</p> <p>A simple kinetic model describing stationary solutions with bifurcated and single-peaked <span class="hlt">current</span> density profiles of a plane electron beam or <span class="hlt">current</span> <span class="hlt">sheet</span> in plasma is presented. A connection is established between the two-dimensional constructions arising in terms of the model and the one-dimensional considerations by Bernstein−Greene−Kruskal facilitating the reconstruction of the distribution function of trapped particles when both the profile of the electric potential and the free particles distribution function are known.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFMSH43C1975L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFMSH43C1975L"><span>Are <span class="hlt">current</span> <span class="hlt">sheets</span> the boundary of fluxtubes in the solar wind? -- A study from multiple spacecraft observation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Li, G.; Arnold, L.; Miao, B.; Yan, Y.</p> <p>2011-12-01</p> <p>G. Li (1,2), L. Arnold (1), B. Miao (3) and Y. Yan (4) (1) Department of Physics, University of Alabama in Huntsville Huntsville, AL, 35899 (2) CSPAR, University of Alabama in Huntsville Huntsville, AL, 35899 (3) School of Earth and Space Sciences, University of Science and Technology of CHINA, Hefei, China (4) Key Laboratory of Solar Activity, National Astronomical Observatories, Chinese Academy of Science, Beijing 100012, China <span class="hlt">Current</span> <span class="hlt">sheets</span> is a common structure in the solar wind and is a significant source of solar wind MHD turbulence intermittency. The origin of these structure is presently unknown. Non-linear interactions of the solar wind MHD turbulence can spontaneously generate these structures. On the other hand, there are proposals that these structures may represent relic structures having solar origins. Using a technique developed in [1], we examine <span class="hlt">current</span> <span class="hlt">sheets</span> in the solar wind from multiple spacecraft. We identify the "single-peak" and "double-peak" events in the solar wind and discuss possible scenarios for these events and its implication of the origin of the <span class="hlt">current</span> <span class="hlt">sheets</span>. [1] Li, G., "Identify <span class="hlt">current-sheet</span>-like structures in the solar wind", ApJL 672, L65, 2008.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22299965-three-dimensional-instabilities-electron-scale-current-sheet-collisionless-magnetic-reconnection','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22299965-three-dimensional-instabilities-electron-scale-current-sheet-collisionless-magnetic-reconnection"><span>Three dimensional instabilities of an electron scale <span class="hlt">current</span> <span class="hlt">sheet</span> in collisionless magnetic reconnection</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Jain, Neeraj; Büchner, Jörg; Max Planck Institute for Solar System Research, Justus-Von-Liebig-Weg-3, Göttingen</p> <p></p> <p>In collisionless magnetic reconnection, electron <span class="hlt">current</span> <span class="hlt">sheets</span> (ECS) with thickness of the order of an electron inertial length form embedded inside ion <span class="hlt">current</span> <span class="hlt">sheets</span> with thickness of the order of an ion inertial length. These ECS's are susceptible to a variety of instabilities which have the potential to affect the reconnection rate and/or the structure of reconnection. We carry out a three dimensional linear eigen mode stability analysis of electron shear flow driven instabilities of an electron scale <span class="hlt">current</span> <span class="hlt">sheet</span> using an electron-magnetohydrodynamic plasma model. The linear growth rate of the fastest unstable mode was found to drop with themore » thickness of the ECS. We show how the nature of the instability depends on the thickness of the ECS. As long as the half-thickness of the ECS is close to the electron inertial length, the fastest instability is that of a translational symmetric two-dimensional (no variations along flow direction) tearing mode. For an ECS half thickness sufficiently larger or smaller than the electron inertial length, the fastest mode is not a tearing mode any more and may have finite variations along the flow direction. Therefore, the generation of plasmoids in a nonlinear evolution of ECS is likely only when the half-thickness is close to an electron inertial length.« less</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li class="active"><span>9</span></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_9 --> <div id="page_10" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li class="active"><span>10</span></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="181"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008cosp...37.3554Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008cosp...37.3554Y"><span>Temporal evolution of a <span class="hlt">Current</span> <span class="hlt">Sheet</span> with Initial Finite Perturbations by Three-dimensional MHD Simulations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yokoyama, Takaaki</p> <p></p> <p>Temporal evolution of a <span class="hlt">current</span> <span class="hlt">sheet</span> with initial perturbations is studied by using the threedimensional resistive magnetohydrodynamic (MHD) simulations. The magnetic reconnection is considered to be the main engine of the energy rele ase in solar flares. The structure of the diffusion region is, however, not stil l understood under the circumstances with enormously large magnetic Reynolds num ber as the solar corona. In particular, the relationship between the flare's macroscopic physics and the microscopic ones are unclear. It is generally believed that the MHD turbulence s hould play a role in the intermediate scale. The initial <span class="hlt">current</span> <span class="hlt">sheet</span> is in an approximately hydromagnetic equilibrium with anti-parallel magnetic field in the y-direction. We imposed a finite-amplitude perturbations (=50ee what happens. Special attention is paid upon the evolution of a three-dimens ional structure in the direction along the initial electric <span class="hlt">current</span> (z-direction ). Our preliminary results are as follows: (1) In the early phase of the evolut ion, high wavenumber modes in the z-direction are excited and grow. (2) Many "X "-type neutral points (lines) are generated along the magnetic neutral line (pla ne) in the <span class="hlt">current</span> <span class="hlt">sheet</span>. When they evolve into the non-linear phase, three-dime nsional structures in the z-direction also evolve. The spatial scale in the z-di rection seems to be almost comparable with that in the xy-plane. (3) The energy release rate is reduced in case of 3D simulations compared with 2D ones probably because of the reduction of the inflow cross sections by the formation of pattc hy structures in the <span class="hlt">current</span> <span class="hlt">sheet</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001EP%26S...53..495B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001EP%26S...53..495B"><span>Spheromaks, solar prominences, and Alfvén instability of <span class="hlt">current</span> <span class="hlt">sheets</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bellan, P. M.; Yee, J.; Hansen, J. F.</p> <p>2001-06-01</p> <p>Three related efforts underway at Caltech are discussed: experimental studies of spheromak formation, experimental simulation of solar prominences, and Alfvén wave instability of <span class="hlt">current</span> <span class="hlt">sheets</span>. Spheromak formation has been studied by using a coaxial magnetized plasma gun to inject helicity-bearing plasma into a very large vacuum chamber. The spheromak is formed without a flux conserver and internal λ profiles have been measured. Spheromak-based technology has been used to make laboratory plasmas having the topology and dynamics of solar prominences. The physics of these structures is closely related to spheromaks (low β, force-free, relaxed state equilibrium) but the boundary conditions and symmetry are different. Like spheromaks, the equilibrium involves a balance between hoop forces, pinch forces, and magnetic tension. It is shown theoretically that if a <span class="hlt">current</span> <span class="hlt">sheet</span> becomes sufficiently thin (of the order of the ion skin depth or smaller), it becomes kinetically unstable with respect to the emission of Alfvén waves and it is proposed that this wave emission is an important aspect of the dynamics of collisionless reconnection.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017ApJ...837...74B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017ApJ...837...74B"><span>Explosive Magnetic Reconnection in Double-<span class="hlt">current</span> <span class="hlt">Sheet</span> Systems: Ideal versus Resistive Tearing Mode</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Baty, Hubert</p> <p>2017-03-01</p> <p>Magnetic reconnection associated with the tearing instability occurring in double-<span class="hlt">current</span> <span class="hlt">sheet</span> systems is investigated within the framework of resistive magnetohydrodynamics (MHD) in a two-dimensional Cartesian geometry. A special emphasis on the existence of fast and explosive phases is taken. First, we extend the recent theory on the ideal tearing mode of a single-<span class="hlt">current</span> <span class="hlt">sheet</span> to a double-<span class="hlt">current</span> layer configuration. A linear stability analysis shows that, in long and thin systems with (length to shear layer thickness) aspect ratios scaling as {S}L9/29 (S L being the Lundquist number based on the length scale L), tearing modes can develop on a fast Alfvénic timescale in the asymptotic limit {S}L\\to ∞ . The linear results are confirmed by means of compressible resistive MHD simulations at relatively high S L values (up to 3× {10}6) for different <span class="hlt">current</span> <span class="hlt">sheet</span> separations. Moreover, the nonlinear evolution of the ideal double tearing mode (IDTM) exhibits a richer dynamical behavior than its single-tearing counterpart, as a nonlinear explosive growth violently ends up with a disruption when the two <span class="hlt">current</span> layers interact trough the merging of plasmoids. The final outcome of the system is a relaxation toward a new state, free of magnetic field reversal. The IDTM dynamics is also compared to the resistive double tearing mode dynamics, which develops in similar systems with smaller aspect ratios, ≳ 2π , and exhibits an explosive secondary reconnection, following an initial slow resistive growth phase. Finally, our results are used to discuss the flaring activity in astrophysical magnetically dominated plasmas, with a particular emphasis on pulsar systems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19930036990&hterms=surface+equipotential&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dsurface%2Bequipotential','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19930036990&hterms=surface+equipotential&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dsurface%2Bequipotential"><span>A scenario for solar wind penetration of earth's magnetic <span class="hlt">tail</span> based on ion composition data from the ISEE 1 spacecraft</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Lennartsson, W.</p> <p>1992-01-01</p> <p>Based on He(2+) and H(-) ion composition data from the Plasma Composition Experiment on ISEE 1, a scenario is proposed for the solar wind penetration of the earth's magnetic <span class="hlt">tail</span>, which does not require that the solar wind plasma be magnetized. While this study does not take issue with the notion that earth's magnetic field merges with the solar wind magnetic field on a regular basis, it focuses on certain aspects of interaction between the solar wind particles and the earth's field, e.g, the fact that the geomagnetic <span class="hlt">tail</span> always has a plasma <span class="hlt">sheet</span>, even during times when the physical signs of magnetic merging are weak or absent. It is argued that the solar plasma enters along slots between the <span class="hlt">tail</span> lobes and the plasma <span class="hlt">sheet</span>, even quite close to earth, convected inward along the plasma <span class="hlt">sheet</span> boundary layer or adjacent to it, by the electric fringe field of the ever present low-latitude magnetopause boundary layer (LLBL). The required E x B drifts are produced by closing LLBL equipotential surfaces through the plasma <span class="hlt">sheet</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016GSL.....3...12M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016GSL.....3...12M"><span>Relation of the auroral substorm to the substorm <span class="hlt">current</span> wedge</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>McPherron, Robert L.; Chu, Xiangning</p> <p>2016-12-01</p> <p>The auroral substorm is an organized sequence of events seen in the aurora near midnight. It is a manifestation of the magnetospheric substorm which is a disturbance of the magnetosphere brought about by the solar wind transfer of magnetic flux from the dayside to the <span class="hlt">tail</span> lobes and its return through the plasma <span class="hlt">sheet</span> to the dayside. The most dramatic feature of the auroral substorm is the sudden brightening and poleward expansion of the aurora. Intimately associated with this expansion is a westward electrical <span class="hlt">current</span> flowing across the bulge of expanding aurora. This <span class="hlt">current</span> is fed by a downward field-aligned <span class="hlt">current</span> (FAC) at its eastern edge and an upward <span class="hlt">current</span> at its western edge. This <span class="hlt">current</span> system is called the substorm <span class="hlt">current</span> wedge (SCW). The SCW forms within a minute of auroral expansion. FAC are created by pressure gradients and field line bending from shears in plasma flow. Both of these are the result of pileup and diversion of plasma flows in the near-earth plasma <span class="hlt">sheet</span>. The origins of these flows are reconnection sites further back in the <span class="hlt">tail</span>. The auroral expansion can be explained by a combination of a change in field line mapping caused by the substorm <span class="hlt">current</span> wedge and a tailward growth of the outer edge of the pileup region. We illustrate this scenario with a complex substorm and discuss some of the problems associated with this interpretation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19900054858&hterms=earth+magnetic+field&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dearth%2Bmagnetic%2Bfield','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19900054858&hterms=earth+magnetic+field&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dearth%2Bmagnetic%2Bfield"><span>A statistical study of magnetic field magnitude changes during substorms in the near earth <span class="hlt">tail</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Lopez, R. E.; Lui, A. T. Y.; Mcentire, R. W.; Potemra, T. A.; Krimigis, S. M.</p> <p>1990-01-01</p> <p>Using AMPTE/CCE data taken in 1985 and 1986 when the CCE apogee (8.8 earth radii) was within 4.5 hours of midnight, 167 injection events in the near-earth magnetotail have been cataloged. These events are exactly or nearly dispersionless on a 72-sec time scale from 25 keV to 285 keV. The changes in the field magnitude are found to be consistent with the expected effects of the diversion/disruption of the cross-<span class="hlt">tail</span> <span class="hlt">current</span> during a substorm, and the latitudinal position of the <span class="hlt">current</span> <span class="hlt">sheet</span> is highly variable within the orbit of CCE. The local time variation of the magnetic-field changes implies that the substorm <span class="hlt">current</span> wedge is composed of longitudinally broad Birkeland <span class="hlt">currents</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018JPlPh..84a9015T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018JPlPh..84a9015T"><span>Development of tearing instability in a <span class="hlt">current</span> <span class="hlt">sheet</span> forming by sheared incompressible flow</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tolman, Elizabeth A.; Loureiro, Nuno F.; Uzdensky, Dmitri A.</p> <p>2018-02-01</p> <p>Sweet-Parker <span class="hlt">current</span> <span class="hlt">sheets</span> in high Lundquist number plasmas are unstable to tearing, suggesting they will not form in physical systems. Understanding magnetic reconnection thus requires study of the stability of a <span class="hlt">current</span> <span class="hlt">sheet</span> as it forms. Formation can occur due to sheared, sub-Alfvénic incompressible flows which narrow the <span class="hlt">sheet</span>. Standard tearing theory (Furth et al. Phys. Fluids, vol. 6 (4), 1963, pp. 459-484, Rutherford, Phys. Fluids, vol. 16 (11), 1973, pp. 1903-1908, Coppi et al. Fizika Plazmy, vol. 2, 1976, pp. 961-966) is not immediately applicable to such forming <span class="hlt">sheets</span> for two reasons: first, because the flow introduces terms not present in the standard calculation; second, because the changing equilibrium introduces time dependence to terms which are constant in the standard calculation, complicating the formulation of an eigenvalue problem. This paper adapts standard tearing mode analysis to confront these challenges. In an initial phase when any perturbations are primarily governed by ideal magnetohydrodynamics, a coordinate transformation reveals that the flow compresses and stretches perturbations. A multiple scale formulation describes how linear tearing mode theory (Furth et al. Phys. Fluids, vol. 6 (4), 1963, pp. 459-484, Coppi et al. Fizika Plazmy, vol. 2, 1976, pp. 961-966) can be applied to an equilibrium changing under flow, showing that the flow affects the separable exponential growth only implicitly, by making the standard scalings time dependent. In the nonlinear Rutherford stage, the coordinate transformation shows that standard theory can be adapted by adding to the stationary rates time dependence and an additional term due to the strengthening equilibrium magnetic field. Overall, this understanding supports the use of flow-free scalings with slight modifications to study tearing in a forming <span class="hlt">sheet</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018Nanot..29B5702M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018Nanot..29B5702M"><span>Effects of electric <span class="hlt">current</span> on individual graphene oxide <span class="hlt">sheets</span> combining in situ transmission electron microscopy and Raman spectroscopy</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Martín, Gemma; Varea, Aïda; Cirera, Albert; Estradé, Sònia; Peiró, Francesca; Cornet, Albert</p> <p>2018-07-01</p> <p>Graphene oxide (GO) is <span class="hlt">currently</span> the object of extensive research because of its potential use in mass production of graphene-based materials, but also due to its tunability which holds great promise for new nanoscale electronic devices and sensors. To obtain a better understanding of the role of GO in electronic nano-devices, the elucidation of the effects of electrical <span class="hlt">current</span> on a single GO <span class="hlt">sheet</span> is of great interest. In this work, in situ transmission electron microscopy is used to study the effects of the electrical <span class="hlt">current</span> flow through single GO <span class="hlt">sheets</span> using an scanning tunneling microscope holder. In order to correlate the applied <span class="hlt">current</span> with the structural properties of GO, Raman spectroscopy is carried out and data analysis is used to obtain information regarding the reduction grade and the disorder degree of the GO <span class="hlt">sheets</span> before and after the application of <span class="hlt">current</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29664411','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29664411"><span>Effects of electric <span class="hlt">current</span> on individual graphene oxide <span class="hlt">sheets</span> combining in situ transmission electron microscopy and Raman spectroscopy.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Martín, Gemma; Varea, Aïda; Cirera, Albert; Estradé, Sònia; Peiró, Francesca; Cornet, Albert</p> <p>2018-04-17</p> <p>Graphene oxide (GO) is <span class="hlt">currently</span> the object of extensive research because of its potential use in mass production of graphene-based materials, but also due to its tunability which holds great promise for new nanoscale electronic devices and sensors. To obtain a better understanding of the role of GO in electronic nano-devices, the elucidation of the effects of electrical <span class="hlt">current</span> on a single GO <span class="hlt">sheet</span> is of great interest. In this work, in situ transmission electron microscopy is used to study the effects of the electrical <span class="hlt">current</span> flow through single GO <span class="hlt">sheets</span> using an scanning tunneling microscope holder. In order to correlate the applied <span class="hlt">current</span> with the structural properties of GO, Raman spectroscopy is carried out and data analysis is used to obtain information regarding the reduction grade and the disorder degree of the GO <span class="hlt">sheets</span> before and after the application of <span class="hlt">current</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018MNRAS.474.3954K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018MNRAS.474.3954K"><span>On the linear stability of sheared and magnetized jets without <span class="hlt">current</span> <span class="hlt">sheets</span> - relativistic case</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kim, Jinho; Balsara, Dinshaw S.; Lyutikov, Maxim; Komissarov, Serguei S.</p> <p>2018-03-01</p> <p>In our prior series of papers, we studied the non-relativistic and relativistic linear stability analysis of magnetized jets that do not have <span class="hlt">current</span> <span class="hlt">sheets</span>. In this paper, we extend our analysis to relativistic jets with a velocity shear and a similar <span class="hlt">current</span> <span class="hlt">sheet</span> free structure. The jets that we study are realistic because we include a velocity shear, a <span class="hlt">current</span> <span class="hlt">sheet</span> free magnetic structure, a relativistic velocity and a realistic thermal pressure so as to achieve overall pressure balance in the unperturbed jet. In order to parametrize the velocity shear, we apply a parabolic profile to the jets' 4-velocity. We find that the velocity shear significantly improves the stability of relativistic magnetized jets. This fact is completely consistent with our prior stability analysis of non-relativistic, sheared jets. The velocity shear mainly plays a role in stabilizing the short wavelength unstable modes for the pinch as well as the kink instability modes. In addition, it also stabilizes the long wavelength fundamental pinch instability mode. We also visualize the pressure fluctuations of each unstable mode to provide a better physical understanding of the enhanced stabilization by the velocity shear. Our overall conclusion is that combining velocity shear with a strong and realistic magnetic field makes relativistic jets even more stable.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.B22B..05Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.B22B..05Y"><span>Deep Submarine <span class="hlt">Tailings</span> Disposal (DSTP) the Proposed Use of Submarine Canyons and Artificial Turbidity <span class="hlt">Currents</span> for the Disposal of Mine Waste: <span class="hlt">Current</span> Practice, Future Plans, and Cumulative Impacts.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Young, R.; Moran, R.</p> <p>2015-12-01</p> <p>The wastes from mining operations ( <span class="hlt">tailings</span>) have been disposed of in the fluvial environment (riverine disposal) and in nearshore marine environments for much of the last century. The scale of modern mining operations has led to increasing use of steep slopes and submarine canyons for deposition of these wastes at depths of 2000m - 4000m. <span class="hlt">Current</span> mine disposal operations in Indonesia and Papua New Guinea which use Deep Sea <span class="hlt">Tailings</span> Placement (DSTP) release volumes between 5000 tpd and 160,000 tpd. Planning is underway by the"Consortium," an industry and government group in Chile which would deposit mine waste of 1M tpd into the Humbolt <span class="hlt">Current</span> Large Marine Ecosystem (HCLME) which provides nearly 20% of the fish biomass harvested on a sustainable basis worldwide. Underwater pipelines discharge <span class="hlt">tailings</span> as a slurry to create a continuous artificial turbidity <span class="hlt">current</span> with particle size distribtions (PSD's) ranging from sand to clay sized fractions. Potential problems arise from benthic smothering, angular particulate uptake by benthic organisms, and from the bioaccumulation of a complex of heavy metals by both benthic and pelagic species. While much is known about the binding of copper and other toxic heavy metals in a reducing environment, little has been done to consider the implications of ocean dumping where 1% of <span class="hlt">tailings</span> discharged may consist of unrecovered heavy metals. Synergistic cumulative impacts to just the HCLME from the dumping of the more than 3M tpy of reactive metals in these <span class="hlt">tailings</span> sediments remains unknown and poses substantial risks. DSTP assumes a stable deep sea depositional environment but upwelling <span class="hlt">currents</span> and plume shear may make this hard to accomplish.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22614096-heliospheric-current-sheet-effects-its-interaction-solar-cosmic-rays','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22614096-heliospheric-current-sheet-effects-its-interaction-solar-cosmic-rays"><span>Heliospheric <span class="hlt">current</span> <span class="hlt">sheet</span> and effects of its interaction with solar cosmic rays</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Malova, H. V., E-mail: hmalova@yandex.ru; Popov, V. Yu.; Grigorenko, E. E.</p> <p>2016-08-15</p> <p>The effects of interaction of solar cosmic rays (SCRs) with the heliospheric <span class="hlt">current</span> <span class="hlt">sheet</span> (HCS) in the solar wind are analyzed. A self-consistent kinetic model of the HCS is developed in which ions with quasiadiabatic dynamics can present. The HCS is considered an equilibrium embedded <span class="hlt">current</span> structure in which two main plasma species with different temperatures (the low-energy background plasma of the solar wind and the higher energy SCR component) contribute to the <span class="hlt">current</span>. The obtained results are verified by comparing with the results of numerical simulations based on solving equations of motion by the particle tracing method in themore » given HCS magnetic field with allowance for SCR particles. It is shown that the HCS is a relatively thin multiscale <span class="hlt">current</span> configuration embedded in a thicker plasma layer. In this case, as a rule, the shear (tangential to the <span class="hlt">sheet</span> <span class="hlt">current</span>) component of the magnetic field is present in the HCS. Taking into account high-energy SCR particles in the HCS can lead to a change of its configuration and the formation of a multiscale embedded structure. Parametric family of solutions is considered in which the <span class="hlt">current</span> balance in the HCS is provided at different SCR temperatures and different densities of the high-energy plasma. The SCR densities are determined at which an appreciable (detectable by satellites) HCS thickening can occur. Possible applications of this modeling to explain experimental observations are discussed.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013hell.conf...16D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013hell.conf...16D"><span>A statistical study of <span class="hlt">current-sheet</span> formation above solar active regions based on selforganized criticality</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dimitropoulou, M.; Isliker, H.; Vlahos, L.; Georgoulis, M.; Anastasiadis, A.; Toutountzi, A.</p> <p>2013-09-01</p> <p>We treat flaring solar active regions as physical systems having reached the self-organized critical state. Their evolving magnetic configurations in the low corona may satisfy an instability criterion, related to the excession of a specific threshold in the curl of the magnetic field. This imposed instability criterion implies an almost zero resistivity everywhere in the solar corona, except in regions where magnetic-field discontinuities and. hence, local <span class="hlt">currents</span>, reach the critical value. In these areas, <span class="hlt">current</span>-driven instabilities enhance the resistivity by many orders of magnitude forming structures which efficiently accelerate charged particles. Simulating the formation of such structures (thought of as <span class="hlt">current</span> <span class="hlt">sheets</span>) via a refined SOC cellular-automaton model provides interesting information regarding their statistical properties. It is shown that the <span class="hlt">current</span> density in such unstable regions follows power-law scaling. Furthermore, the size distribution of the produced <span class="hlt">current</span> <span class="hlt">sheets</span> is best fitted by power laws, whereas their formation probability is investigated against the photospheric magnetic configuration (e.g. Polarity Inversion Lines, Plage). The average fractal dimension of the produced <span class="hlt">current</span> <span class="hlt">sheets</span> is deduced depending on the selected critical threshold. The above-mentioned statistical description of intermittent electric field structures can be used by collisional relativistic test particle simulations, aiming to interpret particle acceleration in flaring active regions and in strongly turbulent media in astrophysical plasmas. The above work is supported by the Hellenic National Space Weather Research Network (HNSWRN) via the THALIS Programme.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20070037448','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20070037448"><span><span class="hlt">Current</span> <span class="hlt">sheet</span> Formation in a Conical Theta Pinch Faraday Accelerator with Radio-Frequency Assisted Discharge</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hallock, Ashley K.; Choueiri, Edgar Y.; Polzin, Kurt A.</p> <p>2007-01-01</p> <p>The inductive formation of <span class="hlt">current</span> <span class="hlt">sheets</span> in a conical theta pinch FARAD (Faraday Accelerator with Radio-frequency Assisted Discharge) thruster is investigated experimentally with time-integrated photography. The goal is to help in understanding the mechanisms and conditions controlling the strength and extent of the <span class="hlt">current</span> <span class="hlt">sheet</span>, which are two indices important for FARAD as a propulsion concept. The profiles of these two indices along the inside walls of the conical acceleration coil are assumed to be related to the profiles of the strength and extent of the luminosity pattern derived from photographs of the discharge. The variations of these profiles as a function of uniform back-fill neutral pressure (with no background magnetic field and all parameters held constant) provided the first clues on the nature and qualitative dependencies of <span class="hlt">current</span> <span class="hlt">sheet</span> formation. It was found that there is an optimal pressure for which both indices reach a maximum and that the rate of change in these indices with pressure differs on either side of this optimal pressure. This allowed the inference that <span class="hlt">current</span> <span class="hlt">sheet</span> formation follows a Townsend-like breakdown mechanism modified by the existence of a finite pressure-dependent radio-frequency-generated electron density background. The observation that the effective location of the luminosity pattern favors the exit-half of the conical coil is explained as the result of the tendency of the inductive discharge circuit to operate near its minimal self-inductance. Movement of the peak in the luminosity pattern towards the upstream side of the cone with increasing pressure is believed to result from the need of the circuit to compensate for the increase in background plasma resistivity due to increasing pressure.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014PhDT.......212C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014PhDT.......212C"><span>Field Emission Properties of Carbon Nanotube Fibers and <span class="hlt">Sheets</span> for a High <span class="hlt">Current</span> Electron Source</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Christy, Larry</p> <p></p> <p>Field emission (FE) properties of carbon nanotube (CNT) fibers from Rice University and the University of Cambridge have been studied for use within a high <span class="hlt">current</span> electron source for a directed energy weapon. Upon reviewing the performance of these two prevalent CNT fibers, cathodes were designed with CNT fibers from the University of Cincinnati Nanoworld Laboratory. Cathodes composed of a single CNT fiber, an array of three CNT fibers, and a nonwoven CNT <span class="hlt">sheet</span> were investigated for FE properties; the goal was to design a cathode with emission <span class="hlt">current</span> in excess of 10 mA. Once the design phase was complete, the cathode samples were fabricated, characterized, and then analyzed to determine FE properties. Electrical conductivity of the CNT fibers was characterized with a 4-probe technique. FE characteristics were measured in an ultra-high vacuum chamber at Wright-Patterson Air Force Base. The arrayed CNT fiber and the enhanced nonwoven CNT <span class="hlt">sheet</span> emitter design demonstrated the most promising FE properties. Future work will include further analysis and cathode design using this nonwoven CNT <span class="hlt">sheet</span> material to increase peak <span class="hlt">current</span> performance during electron emission.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JPhCS.932a2019K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JPhCS.932a2019K"><span>Analytical theory of neutral <span class="hlt">current</span> <span class="hlt">sheets</span> with a sheared magnetic field in collisionless relativistic plasma</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kocharovsky, V. V.; Kocharovsky, Vl V.; Martyanov, V. Yu; Nechaev, A. A.</p> <p>2017-12-01</p> <p>We derive and describe analytically a new wide class of self-consistent magnetostatic structures with sheared field lines and arbitrary energy distributions of particles. To do so we analyze superpositions of two planar <span class="hlt">current</span> <span class="hlt">sheets</span> with orthogonal magnetic fields and cylindrically symmetric momentum distribution functions, such that the magnetic field of one of them is directed along the symmetry axis of the distribution function of the other. These superpositions satisfy the pressure balance equation and allow one to construct configurations with an almost arbitrarily sheared magnetic field. We show that most of previously known <span class="hlt">current</span> <span class="hlt">sheet</span> families with sheared magnetic field lines are included in this novel class.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20120009970','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20120009970"><span><span class="hlt">Current-Sheet</span> Formation and Reconnection at a Magnetic X Line in Particle-in-Cell Simulations</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Black, C.; Antiochos, S. K.; Hesse, M.; Karpen, J. T.; Kuznetsova, M. M.; Zenitani, S.</p> <p>2011-01-01</p> <p>The integration of kinetic effects into macroscopic numerical models is <span class="hlt">currently</span> of great interest to the heliophysics community, particularly in the context of magnetic reconnection. Reconnection governs the large-scale energy release and topological rearrangement of magnetic fields in a wide variety of laboratory, heliophysical, and astrophysical systems. We are examining the formation and reconnection of <span class="hlt">current</span> <span class="hlt">sheets</span> in a simple, two-dimensional X-line configuration using high-resolution particle-in-cell (PIC) simulations. The initial minimum-energy, potential magnetic field is perturbed by excess thermal pressure introduced into the particle distribution function far from the X line. Subsequently, the relaxation of this added stress leads self-consistently to the development of a <span class="hlt">current</span> <span class="hlt">sheet</span> that reconnects for imposed stress of sufficient strength. We compare the time-dependent evolution and final state of our PIC simulations with macroscopic magnetohydrodynamic simulations assuming both uniform and localized electrical resistivities (C. R. DeVore et al., this meeting), as well as with force-free magnetic-field equilibria in which the amount of reconnection across the X line can be constrained to be zero (ideal evolution) or optimal (minimum final magnetic energy). We will discuss implications of our results for understanding magnetic-reconnection onset and cessation at kinetic scales in dynamically formed <span class="hlt">current</span> <span class="hlt">sheets</span>, such as those occurring in the solar corona and terrestrial magnetotail.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSH31B2738S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSH31B2738S"><span>Investigating the Impact of <span class="hlt">Current</span> <span class="hlt">Sheet</span> Crossings on the Propagation of Solar Energetic Particles in the Inner Heliosphere</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schooley, A. K.; Kahler, S.; Lepri, S. T.; Liemohn, M. W.</p> <p>2017-12-01</p> <p>Gradual solar energetic particle events (SEPs) are produced in the solar corona and as these particle events propagate through the inner heliosphere and interplanetary space they might encounter intervening magnetic obstacles such as the heliospheric <span class="hlt">current</span> <span class="hlt">sheet</span>. These encounters may impact SEP acceleration or production. We investigate the extent to which propagation through these intervening structures might be affecting later in-situ SEP measurements at 1 AU. By analyzing large gradual SEP rise phases in a multi-year survey, we investigate the impact crossing a <span class="hlt">current</span> <span class="hlt">sheet</span> or other interplanetary magnetic structure has on in-situ SEP time-intensity profiles. Simultaneous Advanced Composition Explorer (ACE) magnetometer observations and measurements of suprathermal electron pitch angle distributions from ACE's Solar Wind Electron, Proton & Alpha Monitor (SWEPAM) are considered to indicate changes in magnetic polarity and magnetic topology. Potential field source surface models of the heliospheric <span class="hlt">current</span> <span class="hlt">sheet</span> are used to validate potential <span class="hlt">current</span> <span class="hlt">sheet</span> crossing times. We discuss those magnetic obstacles identified that SEPs likely encountered. We discuss the frequency of such encounters, their possible structure and their impact on the SEP time-intensity profiles. Preliminary results indicate that possible intervening interplanetary magnetic structures should be considered when analyzing in-situ SEP observations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSM44A..07Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSM44A..07Y"><span>The Effects of Bursty Bulk Flows on Global-Scale <span class="hlt">Current</span> Systems</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yu, Y.; Cao, J.; Fu, H.; Lu, H.; Yao, Z.</p> <p>2017-12-01</p> <p>Using a global magnetospheric MHD model coupled with a kinetic ring <span class="hlt">current</span> model, we investigate the effects of magnetotail dynamics, particularly the earthward bursty bulk flows (BBFs) produced by the <span class="hlt">tail</span> reconnection, on the global-scale <span class="hlt">current</span> systems. The simulation results indicate that after BBFs brake around X = -10 RE due to the dipolar "magnetic wall," vortices are generated on the edge of the braking region and inside the inner magnetosphere. Each pair of vortex in the inner magnetosphere disturbs the westward ring <span class="hlt">current</span> to arc radially inward as well as toward high latitudes. The resultant pressure gradient on the azimuthal direction induces region-1 sense field-aligned component from the ring <span class="hlt">current</span>, which eventually is diverted into the ionosphere at high latitudes, giving rise to a pair of field-aligned <span class="hlt">current</span> (FAC) eddies in the ionosphere. On the edge of the flow braking region where vortices also emerge, a pair of region-1 sense FACs arises, diverted fromthe cross-<span class="hlt">tail</span> duskward <span class="hlt">current</span>, generating a substorm <span class="hlt">current</span> wedge. This is again attributed to the increase of thermal pressure ahead of the bursty flows turning azimuthally. It is further found that when multiple BBFs, despite their localization, continually and rapidly impinge on the "wall," carrying sufficient <span class="hlt">tail</span> plasma <span class="hlt">sheet</span> population toward the Earth, they can lead to the formation of a new ring <span class="hlt">current</span>. These results indicate the important role that BBFs play in bridging the <span class="hlt">tail</span> and the inner magnetosphere ring <span class="hlt">current</span> and bring new insight into the storm-substorm relation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JGRA..122.6139Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JGRA..122.6139Y"><span>The effects of bursty bulk flows on global-scale <span class="hlt">current</span> systems</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yu, Yiqun; Cao, Jinbin; Fu, Huishan; Lu, Haoyu; Yao, Zhonghua</p> <p>2017-06-01</p> <p>Using a global magnetospheric MHD model coupled with a kinetic ring <span class="hlt">current</span> model, we investigate the effects of magnetotail dynamics, particularly the earthward bursty bulk flows (BBFs) produced by the <span class="hlt">tail</span> reconnection, on the global-scale <span class="hlt">current</span> systems. The simulation results indicate that after BBFs brake around X = -10 RE due to the dipolar "magnetic wall," vortices are generated on the edge of the braking region and inside the inner magnetosphere. Each pair of vortex in the inner magnetosphere disturbs the westward ring <span class="hlt">current</span> to arc radially inward as well as toward high latitudes. The resultant pressure gradient on the azimuthal direction induces region-1 sense field-aligned component from the ring <span class="hlt">current</span>, which eventually is diverted into the ionosphere at high latitudes, giving rise to a pair of field-aligned <span class="hlt">current</span> (FAC) eddies in the ionosphere. On the edge of the flow braking region where vortices also emerge, a pair of region-1 sense FACs arises, diverted from the cross-<span class="hlt">tail</span> duskward <span class="hlt">current</span>, generating a substorm <span class="hlt">current</span> wedge. This is again attributed to the increase of thermal pressure ahead of the bursty flows turning azimuthally. It is further found that when multiple BBFs, despite their localization, continually and rapidly impinge on the "wall," carrying sufficient <span class="hlt">tail</span> plasma <span class="hlt">sheet</span> population toward the Earth, they can lead to the formation of a new ring <span class="hlt">current</span>. These results indicate the important role that BBFs play in bridging the <span class="hlt">tail</span> and the inner magnetosphere ring <span class="hlt">current</span> and bring new insight into the storm-substorm relation.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li class="active"><span>10</span></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_10 --> <div id="page_11" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li class="active"><span>11</span></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="201"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19950047160&hterms=cell+theory&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dcell%2Btheory','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19950047160&hterms=cell+theory&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dcell%2Btheory"><span>A new approach to the linear theory of single-species tearing in two-dimensional quasi-neutral <span class="hlt">sheets</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Brittnacher, M.; Quest, K. B.; Karimabadi, H.</p> <p>1995-01-01</p> <p>We have developed the linear theory of collisionless ion tearing in a two-dimensional magnetotail equilibrium for a single resonant species. We have solved the normal mode problem for tearing instability by an algorithm that employs particle-in-cell simulation to calculate the orbit integrals in the Maxwell-Vlasov eigenmode equation. The results of our single-species tearing analysis can be applied to ion tearing where electron effects are not included. We have calculated the tearing growth rate as a function of the magnetic field component B(sub n) normal to the <span class="hlt">current</span> <span class="hlt">sheet</span> for thick and thin <span class="hlt">current</span> <span class="hlt">sheets</span>, and we show that marginal stability occurs when the normal gyrofrequency Omega(sub n) is comparable to the Harris neutral <span class="hlt">sheet</span> growth rate. A cross-<span class="hlt">tail</span> B(sub y) component has little effect on the growth rate for B(sub y) approximately = B(sub n). Even in the limit B(sub y) much greater than B(sub n), the mode is strongly stabilized by B(sub n). We report than random pitch angle scattering can overcome the stabilizing effect of B(sub n) and drive the growth rate up toward the Harris neutral <span class="hlt">sheet</span> (B(sub n) = 0) value when the pitch angle diffusion rate is comparable to Omega(sub n).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JGRA..122.2795P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JGRA..122.2795P"><span>The most intense <span class="hlt">current</span> <span class="hlt">sheets</span> in the high-speed solar wind near 1 AU</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Podesta, John J.</p> <p>2017-03-01</p> <p>Electric <span class="hlt">currents</span> in the solar wind plasma are investigated using 92 ms fluxgate magnetometer data acquired in a high-speed stream near 1 AU. The minimum resolvable scale is roughly 0.18 s in the spacecraft frame or, using Taylor's "frozen turbulence" approximation, one proton inertial length di in the plasma frame. A new way of identifying <span class="hlt">current</span> <span class="hlt">sheets</span> is developed that utilizes a proxy for the <span class="hlt">current</span> density J obtained from the derivatives of the three orthogonal components of the observed magnetic field B. The most intense <span class="hlt">currents</span> are identified as 5σ events, where σ is the standard deviation of the <span class="hlt">current</span> density. The observed 5σ events are characterized by an average scale size of approximately 3di along the flow direction of the solar wind, a median separation of around 50di or 100di along the flow direction of the solar wind, and a peak <span class="hlt">current</span> density on the order of 0.5 pA/cm2. The associated <span class="hlt">current</span>-carrying structures are consistent with <span class="hlt">current</span> <span class="hlt">sheets</span>; however, the planar geometry of these structures cannot be confirmed using single-point, single-spacecraft measurements. If Taylor's hypothesis continues to hold for the energetically dominant fluctuations at kinetic scales 1<kdi≲40, then the results suggest that the most intense <span class="hlt">current</span>-carrying structures in high-speed wind occur at electron scales, although the peak <span class="hlt">current</span> densities at kinetic and electron scales are predicted to be nearly the same as those found in this study.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMSM43A2487S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMSM43A2487S"><span>Substorms: The Attempt at Magnetospheric Dynamic Equilibrium between Magnetically-Driven Frontside Reconnection and Particle-Driven Reconnection in a Multiple-<span class="hlt">Current-Sheet</span> Magnetotail</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sofko, G. J.; Hussey, G. C.; McWilliams, K. A.; Reimer, A. S.</p> <p>2016-12-01</p> <p>We propose a multi-<span class="hlt">current-sheet</span> model for magnetic substorms. Those storms are normally driven by frontside magnetically-driven reconnection (MDRx), in which the diffusion zone <span class="hlt">current</span> JD and the electric field E have a "load" relationship JD*E >0, indicating transfer if magnetic energy to the particles in the "reconnection jets". As a result of lobe field line transport over the north and south poles, polar cap particles are subject to parallel energization as they flow upward out of the ionosphere. These particles convectively drift toward the equator and subsequently mirror near the Neutral <span class="hlt">Sheet</span> (NSh) region, forming an extended westward NSh <span class="hlt">current</span> <span class="hlt">sheet</span> which is unstable and "tears up" into multiple <span class="hlt">current</span> <span class="hlt">sheets</span>. Each <span class="hlt">current</span> <span class="hlt">sheet</span> has very different behaviour at its ends: (a) strong magnetic pressure and weak particle pressure at its tailward end; (b) strong particle pressure and weak magnetic field at its earthward end. Therefore, in each Separation Zone (SZ) between <span class="hlt">current</span> <span class="hlt">sheets</span>, a strong eastward magnetic curl develops. The associated eastward SZ <span class="hlt">current</span>, caused by diamagnetic electron drift, is squeezed by the repulsion of the westward <span class="hlt">currents</span> tailward and earthward. That <span class="hlt">current</span> becomes intense enough to act as a diffusion zone for "generator-type" or Particle-driven reconnection (PDRx) for which JD*E<0, indicating that the particles return energy to the magnetic field. The PDRx produces a Dipolarization Front (DF) on the earthward side of the SZ and a Plasmoid (PMD) on the tailward side. Such DF-PMD pairs form successively in time and radial downtail SZ distance. In this way, the magnetosphere attempts to achieve a dynamic equilibrium between magnetic and particle energy.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009AGUFMSM11A1544G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009AGUFMSM11A1544G"><span>Effect of <span class="hlt">tail</span> plasma <span class="hlt">sheet</span> conditions on the penetration of the convection electric field in the inner magnetosphere: RCM simulations with self-consistent magnetic field</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gkioulidou, M.; Wang, C.; Lyons, L. R.; Wolf, R.</p> <p>2009-12-01</p> <p>Transport of plasma <span class="hlt">sheet</span> particles into the inner magnetosphere is strongly affected by the penetration of the convection electric field, which is the result of the large-scale magnetosphere ionosphere electromagnetic coupling. This transport, on the other hand, results in plasma heating and magnetic field stretching, which become very significant in the inner plasma <span class="hlt">sheet</span> (inside 20 RE). We have previously run simulations with the Rice Convection Model (RCM), using the Tsyganenko 96 magnetic field model, to investigate how the earthward penetration of electric field depends on plasma <span class="hlt">sheet</span> conditions. Outer proton and electron sources at r ~20 RE, are based on 11 years of Geotail data, and realistically represent the mixture of cold and hot plasma <span class="hlt">sheet</span> population as a function of MLT and interplanetary conditions. We found that shielding of the inner magnetosphere electric field is more efficient for a colder and denser plasma <span class="hlt">sheet</span>, which is found following northward IMF, than for the hotter and more tenuous plasma <span class="hlt">sheet</span> found following southward IMF. Our simulation results so far indicate further earthward penetration of plasma <span class="hlt">sheet</span> particles in response to enhanced convection if the preceding IMF is southward, which leads to weaker electric field shielding. Recently we have integrated the RCM with a magnetic field solver to obtain magnetic fields that are in force balance with given plasma pressures in the equatorial plane. We expect the self-consistent magnetic field to have a pronounced dawn dusk asymmetry due to the asymmetric inner magnetospheric pressure. This should affect the radial distance and MLT of plasma <span class="hlt">sheet</span> penetration into the inner magnetosphere. We are <span class="hlt">currently</span> using this force-balanced and self-consistent model with our realistic boundary conditions to evaluate the dependence of the shielding timescale on pre-existing plasma <span class="hlt">sheet</span> number density and temperature and to more quantitatively determine the correlation between the plasma <span class="hlt">sheet</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015ApJ...807....6C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015ApJ...807....6C"><span>3D MHD Simulation of Flare Supra-Arcade Downflows in a Turbulent <span class="hlt">Current</span> <span class="hlt">Sheet</span> Medium</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cécere, M.; Zurbriggen, E.; Costa, A.; Schneiter, M.</p> <p>2015-07-01</p> <p>Supra-arcade downflows (SADs) are sunward, generally dark, plasma density depletions originated above posteruption flare arcades. In this paper, using 3D MHD simulations we investigate whether the SAD cavities can be produced by a direct combination of the tearing mode and Kelvin-Helmholtz instabilities leading to a turbulent <span class="hlt">current</span> <span class="hlt">sheet</span> (CS) medium or if the <span class="hlt">current</span> <span class="hlt">sheet</span> is merely the background where SADs are produced, triggered by an impulsive deposition of energy. We find that to give an account of the observational dark lane structures an addition of local energy, provided by a reconnection event, is required. We suggest that there may be a closed relation between characteristic SAD sizes and CS widths that must be satisfied to obtain an observable SAD.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22471841-influence-initial-parameters-magnetic-field-plasma-spatial-structure-electric-current-electron-density-current-sheets-formed-helium','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22471841-influence-initial-parameters-magnetic-field-plasma-spatial-structure-electric-current-electron-density-current-sheets-formed-helium"><span>Influence of the initial parameters of the magnetic field and plasma on the spatial structure of the electric <span class="hlt">current</span> and electron density in <span class="hlt">current</span> <span class="hlt">sheets</span> formed in helium</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Ostrovskaya, G. V., E-mail: galya-ostr@mail.ru; Markov, V. S.; Frank, A. G., E-mail: annfrank@fpl.gpi.ru</p> <p></p> <p>The influence of the initial parameters of the magnetic field and plasma on the spatial structure of the electric <span class="hlt">current</span> and electron density in <span class="hlt">current</span> <span class="hlt">sheets</span> formed in helium plasma in 2D and 3D magnetic configurations with X-type singular lines is studied by the methods of holographic interferometry and magnetic measurements. Significant differences in the structures of plasma and <span class="hlt">current</span> <span class="hlt">sheets</span> formed at close parameters of the initial plasma and similar configurations of the initial magnetic fields are revealed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005GApFD..99..433C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005GApFD..99..433C"><span>Wave-induced drift of large floating <span class="hlt">sheets</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Christensen, K. H.; Weber, J. E.</p> <p></p> <p>In this article we study the wave-induced drift of large, flexible shallow floating objects, referred to as <span class="hlt">sheets</span>. When surface waves propagate through a <span class="hlt">sheet</span>, they provide a mean stress on the <span class="hlt">sheet</span>, resulting in a mean drift. In response, the <span class="hlt">sheet</span> generates an Ekman <span class="hlt">current</span>. The drift velocity of the <span class="hlt">sheet</span> is determined by (i) the wave-induced stress, (ii) the viscous stress due to the Ekman <span class="hlt">current</span>, and (iii) the Coriolis force. The <span class="hlt">sheet</span> velocity and the <span class="hlt">current</span> beneath the <span class="hlt">sheet</span> are determined for constant and depth-varying eddy viscosities.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018PhPl...25b2904K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018PhPl...25b2904K"><span>On the influence of the local maxima of total pressure on the <span class="hlt">current</span> <span class="hlt">sheet</span> stability to the kink-like (flapping) mode</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Korovinskiy, D. B.; Erkaev, N. V.; Semenov, V. S.; Ivanov, I. B.; Kiehas, S. A.; Ryzhkov, I. I.</p> <p>2018-02-01</p> <p>The stability of the Fadeev-like <span class="hlt">current</span> <span class="hlt">sheet</span> with respect to transversally propagating kink-like perturbations (flapping mode) is considered in terms of two-dimensional linear magnetohydrodynamic numerical simulations. It is found that the <span class="hlt">current</span> <span class="hlt">sheet</span> is stable when the total pressure minimum is located in the <span class="hlt">sheet</span> center and unstable when the maximum value is reached there. It is shown that an unstable spot of any size enforces the whole <span class="hlt">sheet</span> to be unstable, though the increment of instability decreases with the reduction of the unstable domain. In unstable <span class="hlt">sheets</span>, the dispersion curve of instability shows a good match with the double-gradient (DG) model prediction. Here, the typical growth rate (short-wavelength limit) is close to the DG estimate averaged over the unstable region. In stable configurations, the typical frequency matches the maximum DG estimate. The dispersion curve of oscillations demonstrates a local maximum at wavelength ˜0.7 <span class="hlt">sheet</span> half-width, which is a new feature that is absent in simplified analytical solutions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013atp..prop..192A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013atp..prop..192A"><span><span class="hlt">Current</span> <span class="hlt">Sheets</span> in Pulsar Magnetospheres and Winds: Particle Acceleration and Pulsed Gamma Ray Emission</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Arons, Jonathan</p> <p></p> <p>The research proposed addresses understanding of the origin of non-thermal energy in the Universe, a subject beginning with the discovery of Cosmic Rays and continues, including the study of relativistic compact objects - neutron stars and black holes. Observed Rotation Powered Pulsars (RPPs) have rotational energy loss implying they have TeraGauss magnetic fields and electric potentials as large as 40 PetaVolts. The rotational energy lost is reprocessed into particles which manifest themselves in high energy gamma ray photon emission (GeV to TeV). Observations of pulsars from the FERMI Gamma Ray Observatory, launched into orbit in 2008, have revealed 130 of these stars (and still counting), thus demonstrating the presence of efficient cosmic accelerators within the strongly magnetized regions surrounding the rotating neutron stars. Understanding the physics of these and other Cosmic Accelerators is a major goal of astrophysical research. A new model for particle acceleration in the <span class="hlt">current</span> <span class="hlt">sheets</span> separating the closed and open field line regions of pulsars' magnetospheres, and separating regions of opposite magnetization in the relativistic winds emerging from those magnetopsheres, will be developed. The <span class="hlt">currents</span> established in recent global models of the magnetosphere will be used as input to a magnetic field aligned acceleration model that takes account of the <span class="hlt">current</span> carrying particles' inertia, generalizing models of the terrestrial aurora to the relativistic regime. The results will be applied to the spectacular new results from the FERMI gamma ray observatory on gamma ray pulsars, to probe the physics of the generation of the relativistic wind that carries rotational energy away from the compact stars, illuminating the whole problem of how compact objects can energize their surroundings. The work to be performed if this proposal is funded involves extending and developing concepts from plasma physics on dissipation of magnetic energy in thin <span class="hlt">sheets</span> of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1992AmJPh..60..693S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1992AmJPh..60..693S"><span>Maxwell's theory of eddy <span class="hlt">currents</span> in thin conducting <span class="hlt">sheets</span>, and applications to electromagnetic shielding and MAGLEV</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Saslow, W. M.</p> <p>1992-08-01</p> <p>Using the example of a monopole that is spontaneously generated above a thin conducting <span class="hlt">sheet</span>, the simplicity and power of Maxwell's 1872 theory of eddy <span class="hlt">currents</span> in thin conducting <span class="hlt">sheets</span> is illustrated. This theory employs a receding image construction, with a characteristic recession velocity v0=2/(μ0σd), where the <span class="hlt">sheet</span> has conductivity σ and thickness d. A modern derivation of the theory, employing the magnetic scalar potential, is also presented, with explicit use of the uniqueness theorem. Also discussed are limitations on the theory of which Maxwell, living in a time before the discovery of the electron, could not have been aware. Previous derivations either have not appealed explicitly to the uniqueness theorem, or have employed the now unfamiliar <span class="hlt">current</span> function, and are therefore either incomplete or inaccessible to the modern reader. After the derivation, two important examples considered by Maxwell are presented-a monopole moving above a thin conducting <span class="hlt">sheet</span>, and a monopole above a rotating thin conducting <span class="hlt">sheet</span> (Arago's disk)-and it is argued that the lift force thus obtained makes Maxwell the grandfather, if not the father, of eddy <span class="hlt">current</span> MAGLEV transportation systems. An energy conservation argument is given to derive Davis's result that, for a magnet of arbitrary size and shape moving parallel to a thin conducting <span class="hlt">sheet</span> at a characteristic height h, with velocity v, the ratio of drag force to lift force is equal to v0/v, provided that d≪δc, where δc =√2h/(μ0σv). If d≫δc, the eddy <span class="hlt">currents</span> are confined to a thickness δc, leading to an increase in the dissipation and the drag by a factor of d/δc, so that the ratio of drag to lift force becomes proportional to √v'0/v, where v'0 = 2/(μ0σh). The case of a monopole fixed in position, but oscillating in strength (such as can be simulated by one end of a long, narrow, ac solenoid), is also treated. This is employed to obtain the results for an oscillating magnetic dipole whose moment</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22522235-mhd-simulation-flare-supra-arcade-downflows-turbulent-current-sheet-medium','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22522235-mhd-simulation-flare-supra-arcade-downflows-turbulent-current-sheet-medium"><span>3D MHD SIMULATION OF FLARE SUPRA-ARCADE DOWNFLOWS IN A TURBULENT <span class="hlt">CURRENT</span> <span class="hlt">SHEET</span> MEDIUM</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Cécere, M.; Zurbriggen, E.; Costa, A.</p> <p>2015-07-01</p> <p>Supra-arcade downflows (SADs) are sunward, generally dark, plasma density depletions originated above posteruption flare arcades. In this paper, using 3D MHD simulations we investigate whether the SAD cavities can be produced by a direct combination of the tearing mode and Kelvin–Helmholtz instabilities leading to a turbulent <span class="hlt">current</span> <span class="hlt">sheet</span> (CS) medium or if the <span class="hlt">current</span> <span class="hlt">sheet</span> is merely the background where SADs are produced, triggered by an impulsive deposition of energy. We find that to give an account of the observational dark lane structures an addition of local energy, provided by a reconnection event, is required. We suggest that there maymore » be a closed relation between characteristic SAD sizes and CS widths that must be satisfied to obtain an observable SAD.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22356686-magnetoacoustic-waves-propagating-along-dense-slab-harris-current-sheet-wavelet-spectra','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22356686-magnetoacoustic-waves-propagating-along-dense-slab-harris-current-sheet-wavelet-spectra"><span>Magnetoacoustic waves propagating along a dense slab and Harris <span class="hlt">current</span> <span class="hlt">sheet</span> and their wavelet spectra</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Mészárosová, Hana; Karlický, Marian; Jelínek, Petr</p> <p></p> <p><span class="hlt">Currently</span>, there is a common endeavor to detect magnetoacoustic waves in solar flares. This paper contributes to this topic using an approach of numerical simulations. We studied a spatial and temporal evolution of impulsively generated fast and slow magnetoacoustic waves propagating along the dense slab and Harris <span class="hlt">current</span> <span class="hlt">sheet</span> using two-dimensional magnetohydrodynamic numerical models. Wave signals computed in numerical models were used for computations of the temporal and spatial wavelet spectra for their possible comparison with those obtained from observations. It is shown that these wavelet spectra allow us to estimate basic parameters of waveguides and perturbations. It was foundmore » that the wavelet spectra of waves in the dense slab and <span class="hlt">current</span> <span class="hlt">sheet</span> differ in additional wavelet components that appear in association with the main tadpole structure. These additional components are new details in the wavelet spectrum of the signal. While in the dense slab this additional component is always delayed after the tadpole head, in the <span class="hlt">current</span> <span class="hlt">sheet</span> this component always precedes the tadpole head. It could help distinguish a type of the waveguide in observed data. We present a technique based on wavelets that separates wave structures according to their spatial scales. This technique shows not only how to separate the magnetoacoustic waves and waveguide structure in observed data, where the waveguide structure is not known, but also how propagating magnetoacoustic waves would appear in observations with limited spatial resolutions. The possibilities detecting these waves in observed data are mentioned.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMSM13D4197M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMSM13D4197M"><span>Catapult <span class="hlt">current</span> <span class="hlt">sheet</span> relaxation model confirmed by THEMIS observations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Machida, S.; Miyashita, Y.; Ieda, A.; Nose, M.; Angelopoulos, V.; McFadden, J. P.</p> <p>2014-12-01</p> <p>In this study, we show the result of superposed epoch analysis on the THEMIS probe data during the period from November, 2007 to April, 2009 by setting the origin of time axis to the substorm onset determined by Nishimura with THEMIS all sky imager (THEMS/ASI) data (http://www.atmos.ucla.edu/~toshi/files/paper/Toshi_THEMIS_GBO_list_distribution.xls). We confirmed the presence of earthward flows which can be associated with north-south auroral streamers during the substorm growth phase. At around X = -12 Earth radii (Re), the northward magnetic field and its elevation angle decreased markedly approximately 4 min before substorm onset. A northward magnetic-field increase associated with pre-onset earthward flows was found at around X = -17Re. This variation indicates the occurrence of the local depolarization. Interestingly, in the region earthwards of X = -18Re, earthward flows in the central plasma <span class="hlt">sheet</span> (CPS) reduced significantly about 3min before substorm onset. However, the earthward flows enhanced again at t = -60 sec in the region around X = -14 Re, and they moved toward the Earth. At t = 0, the dipolarization of the magnetic field started at X ~ -10 Re, and simultaneously the magnetic reconnection started at X ~ -20 Re. Synthesizing these results, we can confirm the validity of our catapult <span class="hlt">current</span> <span class="hlt">sheet</span> relaxation model.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19850015098','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19850015098"><span>Periodic substorm activity in the geomagnetic <span class="hlt">tail</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Huang, C. Y.; Eastman, T. E.; Frank, L. A.; Williams, D. J.</p> <p>1983-01-01</p> <p>On 19 May 1978 an anusual series of events is observed with the Quadrispherical LEPEDEA on board the ISEE-1 satellite in the Earth's geomagnetic <span class="hlt">tail</span>. For 13 hours periodic bursts of both ions and electrons are seen in all the particle detectors on the spacecraft. On this day periodic activity is also seen on the ground, where multiple intensifications of the electrojets are observed. At the same time the latitudinal component of the interplanetary magnetic field shows a number of strong southward deflections. It is concluded that an extended period of substorm activity is occurring, which causes repeated thinnings and recoveries of the plasma <span class="hlt">sheet</span>. These are detected by ISEE, which is situated in the plasma <span class="hlt">sheet</span> boundary layer, as periodic dropouts and reappearances of the plasma. Comparisons of the observations at ISEE with those at IMP-8, which for a time is engulfed by the plasma <span class="hlt">sheet</span>, indicate that the activity is relatively localized in spatial extent. For this series of events it is clear that a global approach to magnetospheric dynamics, e.g., reconnection, is inappropriate.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22590585-importance-band-tail-recombination-current-collection-open-circuit-voltage-cztsse-solar-cells','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22590585-importance-band-tail-recombination-current-collection-open-circuit-voltage-cztsse-solar-cells"><span>The importance of band <span class="hlt">tail</span> recombination on <span class="hlt">current</span> collection and open-circuit voltage in CZTSSe solar cells</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Moore, James E.; Purdue University, West Lafayette, Indiana 47907; Hages, Charles J.</p> <p>2016-07-11</p> <p>Cu{sub 2}ZnSn(S,Se){sub 4} (CZTSSe) solar cells typically exhibit high short-circuit <span class="hlt">current</span> density (J{sub sc}), but have reduced cell efficiencies relative to other thin film technologies due to a deficit in the open-circuit voltage (V{sub oc}), which prevent these devices from becoming commercially competitive. Recent research has attributed the low V{sub oc} in CZTSSe devices to small scale disorder that creates band <span class="hlt">tail</span> states within the absorber band gap, but the physical processes responsible for this V{sub oc} reduction have not been elucidated. In this paper, we show that carrier recombination through non-mobile band <span class="hlt">tail</span> states has a strong voltage dependencemore » and is a significant performance-limiting factor, and including these effects in simulation allows us to simultaneously explain the V{sub oc} deficit, reduced fill factor, and voltage-dependent quantum efficiency with a self-consistent set of material parameters. Comparisons of numerical simulations to measured data show that reasonable values for the band <span class="hlt">tail</span> parameters (characteristic energy, capture rate) can account for the observed low V{sub oc}, high J{sub sc}, and voltage dependent collection efficiency. These results provide additional evidence that the presence of band <span class="hlt">tail</span> states accounts for the low efficiencies of CZTSSe solar cells and further demonstrates that recombination through non-mobile band <span class="hlt">tail</span> states is the dominant efficiency limiting mechanism.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014cosp...40E1507K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014cosp...40E1507K"><span>Analogies between Jovian magnetodisk and heliospheric <span class="hlt">current</span> <span class="hlt">sheet</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kislov, Roman; Khabarova, Olga; Malova, Helmi</p> <p></p> <p>Recently due to the development of spatial missions the famous model by E. Parker [1] faced with some problems, such as the effect of magnetic flux excess and the existence of latitude component of magnetic field [2]. Thus the incomplete knowledge about large scale <span class="hlt">current</span> system of heliospheric <span class="hlt">current</span> <span class="hlt">sheet</span> (HCS) motivated us to construct and investigate the self-consistent axisymmetric stationary MHD model of HCS and to compare it with earlier presented model of Jupiterian magnetodisk [3]. Both HCS and magnetodisk have inner plasma sources (i.e. the Sun in case of HCS and satellite Io in case of Jupiter); also they depend on the centrifugal force at small distances and on corotation processes. They both have strong radial component of <span class="hlt">current</span> density, thin elongated structure etc. Thus in the frame of the MHD model we have calculated for HCS the parallel <span class="hlt">currents</span> (analogous to Jovian Birkeland <span class="hlt">currents</span>) and we obtained the latitude component of the magnetic field. The results of the model allowed us to explain the magnetic flux excess by the existence of the self-consistent HCS magnetic field. The decrease of radial magnetic field from the distance from the Sun as the power -5/3 obtained by numerical calculations is in good agreement with experimental data. Generally this model can be applied for the quiet period of the low solar activity when the perturbation of HCS structure named “ballerina skirt” does not play any role. References: 1. Parker E. N., Astrophys. J., V. 128, 664, pp. 664-676, 1958. 2. Khabarova O. V., V. 90, No.11, pp. 919-935, 2013. 3. Kislov R.A. et al., Bull. MSU, Physics and Astron., 2013</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFMSM43A1906L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFMSM43A1906L"><span>A statistical study of the THEMIS satellite data for plasma <span class="hlt">sheet</span> electrons carrying auroral upward field-aligned <span class="hlt">currents</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lee, S.; Shiokawa, K.; McFadden, J. P.</p> <p>2010-12-01</p> <p>The magnetospheric electron precipitation along the upward field-aligned <span class="hlt">currents</span> without the potential difference causes diffuse aurora, and the magnetospheric electrons accelerated by a field-aligned potential difference cause the intense and bright type of aurora, namely discrete aurora. In this study, we are trying to find out when and where the aurora can be caused with or without electron acceleration. We statistically investigate electron density, temperature, thermal <span class="hlt">current</span>, and conductivity in the plasma <span class="hlt">sheet</span> using the data from the electrostatic analyzer (ESA) onboard the THEMIS-D satellite launched in 2007. According to Knight (Planet. Space Sci., 1973) and Lyons (JGR, 1980), the thermal <span class="hlt">current</span>, jth(∝ nT^(1/2) where n is electron density and T is electron temperature in the plasma <span class="hlt">sheet</span>), represents the upper limit to field aligned <span class="hlt">current</span> that can be carried by magnetospheric electrons without field-aligned potential difference. The conductivity, K(∝ nT^(-1/2)), represents the efficiency of the upward field-aligned <span class="hlt">current</span> (j) that the field-aligned potential difference (V) can produce (j=KV). Therefore, estimating jth and K in the plasma <span class="hlt">sheet</span> is important in understanding the ability of plasma <span class="hlt">sheet</span> electrons to carry the field-aligned <span class="hlt">current</span> which is driven by various magnetospheric processes such as flow shear and azimuthal pressure gradient. Similar study was done by Shiokawa et al. (2000) based on the auroral electron data obtained by the DMSP satellites above the auroral oval and the AMPTE/IRM satellite in the near Earth plasma <span class="hlt">sheet</span> at 10-18 Re on February-June 1985 and March-June 1986 during the solar minimum. The purpose of our study is to examine auroral electrons with pitch angle information inside 12 Re where Shiokawa et al. (2000) did not investigate well. For preliminary result, we found that in the dawn side inner magnetosphere (source of the region 2 <span class="hlt">current</span>), electrons can make sufficient thermal <span class="hlt">current</span> without field</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19820040615&hterms=divided+attention&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Ddivided%2Battention','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19820040615&hterms=divided+attention&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Ddivided%2Battention"><span><span class="hlt">Current</span> status of solar cell performance of unconventional silicon <span class="hlt">sheets</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Yoo, H. I.; Liu, J. K.</p> <p>1981-01-01</p> <p>It is pointed out that activities in recent years directed towards reduction in the cost of silicon solar cells for terrestrial photovoltaic applications have resulted in impressive advancements in the area of silicon <span class="hlt">sheet</span> formation from melt. The techniques used in the process of <span class="hlt">sheet</span> formation can be divided into two general categories. All approaches in one category require subsequent ingot wavering. The various procedures of the second category produce silicon in <span class="hlt">sheet</span> form. The performance of baseline solar cells is discussed. The baseline process included identification marking, slicing to size, and surface treatment (etch-polishing) when needed. Attention is also given to the performance of cells with process variations, and the effects of <span class="hlt">sheet</span> quality on performance and processing.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JGRA..120.3415K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JGRA..120.3415K"><span>Distribution of energetic oxygen and hydrogen in the near-Earth plasma <span class="hlt">sheet</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kronberg, E. A.; Grigorenko, E. E.; Haaland, S. E.; Daly, P. W.; Delcourt, D. C.; Luo, H.; Kistler, L. M.; Dandouras, I.</p> <p>2015-05-01</p> <p>The spatial distributions of different ion species are useful indicators for plasma <span class="hlt">sheet</span> dynamics. In this statistical study based on 7 years of Cluster observations, we establish the spatial distributions of oxygen ions and protons at energies from 274 to 955 keV, depending on geomagnetic and solar wind (SW) conditions. Compared with protons, the distribution of energetic oxygen has stronger dawn-dusk asymmetry in response to changes in the geomagnetic activity. When the interplanetary magnetic field (IMF) is directed southward, the oxygen ions show significant acceleration in the <span class="hlt">tail</span> plasma <span class="hlt">sheet</span>. Changes in the SW dynamic pressure (Pdyn) affect the oxygen and proton intensities in the same way. The energetic protons show significant intensity increases at the near-Earth duskside during disturbed geomagnetic conditions, enhanced SW Pdyn, and southward IMF, implying there location of effective inductive acceleration mechanisms and a strong duskward drift due to the increase of the magnetic field gradient in the near-Earth <span class="hlt">tail</span>. Higher losses of energetic ions are observed in the dayside plasma <span class="hlt">sheet</span> under disturbed geomagnetic conditions and enhanced SW Pdyn. These observations are in agreement with theoretical models.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JPlPh..82c9005D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JPlPh..82c9005D"><span>Full particle-in-cell simulations of kinetic equilibria and the role of the initial <span class="hlt">current</span> <span class="hlt">sheet</span> on steady asymmetric magnetic reconnection</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dargent, J.; Aunai, N.; Belmont, G.; Dorville, N.; Lavraud, B.; Hesse, M.</p> <p>2016-06-01</p> <p>> Tangential <span class="hlt">current</span> <span class="hlt">sheets</span> are ubiquitous in space plasmas and yet hard to describe with a kinetic equilibrium. In this paper, we use a semi-analytical model, the BAS model, which provides a steady ion distribution function for a tangential asymmetric <span class="hlt">current</span> <span class="hlt">sheet</span> and we prove that an ion kinetic equilibrium produced by this model remains steady in a fully kinetic particle-in-cell simulation even if the electron distribution function does not satisfy the time independent Vlasov equation. We then apply this equilibrium to look at the dependence of magnetic reconnection simulations on their initial conditions. We show that, as the <span class="hlt">current</span> <span class="hlt">sheet</span> evolves from a symmetric to an asymmetric upstream plasma, the reconnection rate is impacted and the X line and the electron flow stagnation point separate from one another and start to drift. For the simulated systems, we investigate the overall evolution of the reconnection process via the classical signatures discussed in the literature and searched in the Magnetospheric MultiScale data. We show that they seem robust and do not depend on the specific details of the internal structure of the initial <span class="hlt">current</span> <span class="hlt">sheet</span>.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li class="active"><span>11</span></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_11 --> <div id="page_12" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active"><span>12</span></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="221"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMSH51B2590D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMSH51B2590D"><span>The Onset of Magnetic Reconnection: Tearing Instability in <span class="hlt">Current</span> <span class="hlt">Sheets</span> with a Guide Field</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Daldorff, L. K. S.; Klimchuk, J. A.; Knizhnik, K. J.</p> <p>2016-12-01</p> <p>Magnetic reconnection is fundamental to many solar phenomena, ranging from coronal heating, to jets, to flares and CMEs. A poorly understood yet crucial aspect of reconnection is that it does not occur until magnetic stresses have built to sufficiently high levels for significant energy release. If reconnection were to happen too soon, coronal heating would be weak and flares would be small. As part of our program to study the onset conditions for magnetic reconnection, we have investigated the instability of <span class="hlt">current</span> <span class="hlt">sheets</span> to tearing. Surprisingly little work has been done on this problem for <span class="hlt">sheets</span> that include a guide field, i.e., for which the field rotates by less than 180 degrees. This is the most common situation on the Sun. We present numerical 3D resistive MHD simulations of several <span class="hlt">sheets</span> and show how the behaviour depends on the shear angle (rotation). We compare our results to the predictions of linear theory and discuss the nonlinear evolution in terms of plasmoid formation and the interaction of different oblique tearing modes. The relevance to the Sun is explained.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013QSRv...64...33I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013QSRv...64...33I"><span>The Svalbard-Barents Sea ice-<span class="hlt">sheet</span> - Historical, <span class="hlt">current</span> and future perspectives</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ingólfsson, Ólafur; Landvik, Jon Y.</p> <p>2013-03-01</p> <p>The history of research on the Late Quaternary Svalbard-Barents Sea ice <span class="hlt">sheet</span> mirrors the developments of ideas and the shifts of paradigms in glacial theory over the past 150 years. Since the onset of scientific research there in the early 19th Century, Svalbard has been a natural laboratory where ideas and concepts have been tested, and played an important (but rarely acknowledged) role in the break-through of the Ice Age theory in the 1870's. The history of how the scientific perception of the Svalbard-Barents sea ice <span class="hlt">sheet</span> developed in the mid-20th Century also tells a story of how a combination of fairly scattered and often contradictory observational data, and through both deductive and inductive reasoning, could outline a major ice <span class="hlt">sheet</span> that had left but few tangible fingerprints. Since the 1980's, with increased terrestrial stratigraphical data, ever more marine geological evidence and better chronological control of glacial events, our perception of the Svalbard-Barents Sea ice <span class="hlt">sheet</span> has changed. The first reconstructions depicted it as a static, concentric, single-domed ice <span class="hlt">sheet</span>, with ice flowing from an ice divide over the central northern Barents Sea that expanded and declined in response to large-scale, Late Quaternary climate fluctuations, and which was more or less in tune with other major Northern Hemisphere ice <span class="hlt">sheets</span>. We now increasingly perceive it as a very dynamic, multidomed ice <span class="hlt">sheet</span>, controlled by climate fluctuations, relative sea-level change, as well as subglacial topography, substrate properties and basal temperature. In this respect, the Svalbard-Barents Sea ice <span class="hlt">sheet</span> will increasingly hold the key for understanding the dynamics and processes of how marine-based ice <span class="hlt">sheets</span> build-up and decay.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19900065489&hterms=GERD&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DGERD','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19900065489&hterms=GERD&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DGERD"><span>The magnetosphere of Neptune - Its response to daily rotation</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Voigt, Gerd-Hannes; Ness, Norman F.</p> <p>1990-01-01</p> <p>The Neptunian magnetosphere periodically changes every eight hours between a pole-on magnetosphere with only one polar cusp and an earth-type magnetosphere with two polar cusps. In the pole-on configuration, the <span class="hlt">tail</span> <span class="hlt">current</span> <span class="hlt">sheet</span> has an almost circular shape with plasma <span class="hlt">currents</span> closing entirely within the magnetosphere. Eight hours later the <span class="hlt">tail</span> <span class="hlt">current</span> <span class="hlt">sheet</span> assumes an almost flat shape with plasma <span class="hlt">currents</span> touching the magnetotail boundary and closing over the <span class="hlt">tail</span> magnetopause. Magnetic field and <span class="hlt">tail</span> <span class="hlt">current</span> <span class="hlt">sheet</span> configurations have been calculated in a three-dimensional model, but the plasma- and thermodynamic conditions were investigated in a simplified two-dimensional MHD equilibrium magnetosphere. It was found that the free energy in the <span class="hlt">tail</span> region of the two-dimensional model becomes independent of the dipole tilt angle. It is conjectured that the Neptunian magnetotail might assume quasi-static equilibrium states that make the free energy of the system independent of its daily rotation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017QSRv..169...13D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017QSRv..169...13D"><span><span class="hlt">Current</span> state and future perspectives on coupled ice-<span class="hlt">sheet</span> - sea-level modelling</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>de Boer, Bas; Stocchi, Paolo; Whitehouse, Pippa L.; van de Wal, Roderik S. W.</p> <p>2017-08-01</p> <p>The interaction between ice-<span class="hlt">sheet</span> growth and retreat and sea-level change has been an established field of research for many years. However, recent advances in numerical modelling have shed new light on the precise interaction of marine ice <span class="hlt">sheets</span> with the change in near-field sea level, and the related stability of the grounding line position. Studies using fully coupled ice-<span class="hlt">sheet</span> - sea-level models have shown that accounting for gravitationally self-consistent sea-level change will act to slow down the retreat and advance of marine ice-<span class="hlt">sheet</span> grounding lines. Moreover, by simultaneously solving the 'sea-level equation' and modelling ice-<span class="hlt">sheet</span> flow, coupled models provide a global field of relative sea-level change that is consistent with dynamic changes in ice-<span class="hlt">sheet</span> extent. In this paper we present an overview of recent advances, possible caveats, methodologies and challenges involved in coupled ice-<span class="hlt">sheet</span> - sea-level modelling. We conclude by presenting a first-order comparison between a suite of relative sea-level data and output from a coupled ice-<span class="hlt">sheet</span> - sea-level model.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017ApJ...847...98J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017ApJ...847...98J"><span>Oscillations Excited by Plasmoids Formed During Magnetic Reconnection in a Vertical Gravitationally Stratified <span class="hlt">Current</span> <span class="hlt">Sheet</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jelínek, P.; Karlický, M.; Van Doorsselaere, T.; Bárta, M.</p> <p>2017-10-01</p> <p>Using the FLASH code, which solves the full set of the 2D non-ideal (resistive) time-dependent magnetohydrodynamic (MHD) equations, we study processes during the magnetic reconnection in a vertical gravitationally stratified <span class="hlt">current</span> <span class="hlt">sheet</span>. We show that during these processes, which correspond to processes in solar flares, plasmoids are formed due to the tearing mode instability of the <span class="hlt">current</span> <span class="hlt">sheet</span>. These plasmoids move upward or downward along the vertical <span class="hlt">current</span> <span class="hlt">sheet</span> and some of them merge into larger plasmoids. We study the density and temperature structure of these plasmoids and their time evolution in detail. We found that during the merging of two plasmoids, the resulting larger plasmoid starts to oscillate with a period largely determined by L/{c}{{A}}, where L is the size of the plasmoid and c A is the Alfvén speed in the lateral parts of the plasmoid. In our model, L/{c}{{A}} evaluates to ˜ 25 {{s}}. Furthermore, the plasmoid moving downward merges with the underlying flare arcade, which causes oscillations of the arcade. In our model, the period of this arcade oscillation is ˜ 35 {{s}}, which also corresponds to L/{c}{{A}}, but here L means the length of the loop and c A is the average Alfvén speed in the loop. We also show that the merging process of the plasmoid with the flare arcade is a complex process as presented by complex density and temperature structures of the oscillating arcade. Moreover, all these processes are associated with magnetoacoustic waves produced by the motion and merging of plasmoids.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018JGRA..123..548R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018JGRA..123..548R"><span>The Magnetic Field Structure of Mercury's Magnetotail</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rong, Z. J.; Ding, Y.; Slavin, J. A.; Zhong, J.; Poh, G.; Sun, W. J.; Wei, Y.; Chai, L. H.; Wan, W. X.; Shen, C.</p> <p>2018-01-01</p> <p>In this study, we use the magnetic field data measured by MErcury Surface, Space ENvironment, GEochemistry, and Ranging from 2011 to 2015 to investigate the average magnetic field morphology of Mercury's magnetotail in the down <span class="hlt">tail</span> 0-3 <fi>R</fi><fi>M</fi> (<fi>R</fi><fi>M</fi> = 2,440 km, Mercury's radius). It is found that Mercury has a terrestrial-like magnetotail; the magnetic field structure beyond 1.5 <fi>R</fi><fi>M</fi> down <span class="hlt">tail</span> is stretched significantly with typical lobe field 50 nT. A cross-<span class="hlt">tail</span> <span class="hlt">current</span> <span class="hlt">sheet</span> separating the antiparallel field lines of lobes is present in the equatorial plane. The magnetotail width in north-south direction is about 5 <fi>R</fi><fi>M</fi>, while the transverse width is about 4 <fi>R</fi><fi>M</fi>. Thus, the magnetotail shows elongation along the north-south direction. At the cross-<span class="hlt">tail</span> <span class="hlt">current</span> <span class="hlt">sheet</span> center, the normal component of magnetic field (10-20 nT) is much larger than the cross-<span class="hlt">tail</span> component. The lobe-field-aligned component of magnetic field over <span class="hlt">current</span> <span class="hlt">sheet</span> can be well fitted by Harris <span class="hlt">sheet</span> model. The curvature radius of field lines at <span class="hlt">sheet</span> center usually reaches a minimum around midnight (100-200 km) with stronger <span class="hlt">current</span> density (40-50 nA/m2), while the curvature radius increases toward both flanks (400-600 km) with the decreased <span class="hlt">current</span> density (about 20 nA/m2). The half-thickness of <span class="hlt">current</span> <span class="hlt">sheet</span> around midnight is about 0.25 <fi>R</fi><fi>M</fi> or 600 km, and the inner edge of <span class="hlt">current</span> <span class="hlt">sheet</span> is located at the down <span class="hlt">tail</span> about 1.5 <fi>R</fi><fi>M</fi>. Our results about the field structure in the near Mercury's <span class="hlt">tail</span> show an evident dawn-dusk asymmetry as that found in the Earth's magnetotail, but reasons should be different. Possible reasons are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMSH41A2528P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMSH41A2528P"><span>Double <span class="hlt">Current</span> <span class="hlt">Sheet</span> Instabilities and the Transition to Turbulence.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pucci, F.; Velli, M.; Biferale, L.; Sahoo, G.</p> <p>2016-12-01</p> <p>The double tearing instability has often been studied as a proxy for the m=1 kink mode in cylindrical plasma. In this paper we describe the results of 3D simulations of an initially periodic double <span class="hlt">current</span> <span class="hlt">sheet</span> described by Harris equilibria with a guide field in two cases: 1) zero net helicity and an average magnetic field and 2) a well defined helicity (force free but non constant alpha). We study and contrast the de-stabilization and transition to turbulence for these two cases: we describe spectra, cascades, and possible application to heliospheric phenomena, in particular CME evolution and relaxation. The research leading to these results has received fund- ing from the European Union's Seventh Framework Pro- gramme (FP7/2007-2013) under grant agreement No. 339032</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFMSM34B..04D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFMSM34B..04D"><span>Cluster observations of Shear-mode surface waves diverging from Geomagnetic <span class="hlt">Tail</span> reconnection</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dai, L.; Wygant, J. R.; Dombeck, J. P.; Cattell, C. A.; Thaller, S. A.; Mouikis, C.; Balogh, A.; Reme, H.</p> <p>2010-12-01</p> <p>We present the first Cluster spacecraft study of the intense (δB/B~0.5, δE/VAB~0.5) equatorial plane surface waves diverging from magnetic reconnection in the geomagnetic <span class="hlt">tail</span> at ~17 Re. Using phase lag analysis with multi-spacecraft measurements, we quantitatively determine the wavelength and phase velocity of the waves with spacecraft frame frequencies from 0.03 Hz to 1 Hz and wavelengths from much larger (4Re) than to comparable to the H+ gyroradius (~300km). The phase velocities track the strong variations in the equatorial plane projection of the reconnection outflow velocity perpendicular to the magnetic field. The propagation direction and wavelength of the observed surface waves resemble those of flapping waves of the magnetotail <span class="hlt">current</span> <span class="hlt">sheet</span>, suggesting a same origin shared by both of these waves. The observed waves appear ubiquitous in the outflows near magnetotail reconnection. Evidence is found that the observed waves are associated with velocity shear in reconnection outflows. Analysis shows that observed waves are associated with strong field-aligned Alfvenic Poynting flux directed away from the reconnection region toward Earth. These observations present a scenario in which the observed surface waves are driven and convected through a velocity-shear type instability by high-speed (~1000km) reconnection outflows tending to slow down due to power dissipation through Poynting flux. The mapped Poynting flux (100ergs/cm2s) and longitudinal scales (10-100 km) to 100km altitude suggest that the observed waves and their motions are an important boundary condition for night-side aurora. Figure: a) The BX-GSM in the geomagnetic <span class="hlt">tail</span> <span class="hlt">current</span> <span class="hlt">sheet</span>. b) The phase difference wavelet spectrum between Bz_GSM from SC2 and SC3, used to determine the wave phase velocity, is correlated with the reconnection outflow velocity (represented by H+ VX-GSM) c) The spacecraft trajectory through magnetotail reconnection. d) The observed equatorial plane surface wave</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22663463-energetic-particles-kevmev-energies-observed-near-reconnecting-current-sheets-au','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22663463-energetic-particles-kevmev-energies-observed-near-reconnecting-current-sheets-au"><span>Energetic Particles of keV–MeV Energies Observed near Reconnecting <span class="hlt">Current</span> <span class="hlt">Sheets</span> at 1 au</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Khabarova, Olga V.; Zank, Gary P.</p> <p>2017-07-01</p> <p>We provide evidence for particle acceleration up to ∼5 MeV at reconnecting <span class="hlt">current</span> <span class="hlt">sheets</span> in the solar wind based on both case studies and a statistical analysis of the energetic ion and electron flux data from the five Advanced Composition Explorer Electron, Proton, and Alpha Monitor (EPAM) detectors. The case study of a typical reconnection exhaust event reveals (i) a small-scale peak of the energetic ion flux observed in the vicinity of the reconnection exhaust and (ii) a long-timescale atypical energetic particle event (AEPE) encompassing the reconnection exhaust. AEPEs associated with reconnecting strong <span class="hlt">current</span> <span class="hlt">sheets</span> last for many hours, evenmore » days, as confirmed by statistical studies. The case study shows that time-intensity profiles of the ion flux may vary significantly from one EPAM detector to another partially because of the local topology of magnetic fields, but mainly because of the impact of upstream magnetospheric events; therefore, the occurrence of particle acceleration can be hidden. The finding of significant particle energization within a time interval of ±30 hr around reconnection exhausts is supported by a superposed epoch analysis of 126 reconnection exhaust events. We suggest that energetic particles initially accelerated via prolonged magnetic reconnection are trapped and reaccelerated in small- or medium-scale magnetic islands surrounding the reconnecting <span class="hlt">current</span> <span class="hlt">sheet</span>, as predicted by the transport theory of Zank et al. Other mechanisms of initial particle acceleration can contribute also.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22113418-general-formulation-magnetohydrodynamic-wave-propagation-fire-hose-mirror-instabilities-harris-type-current-sheets','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22113418-general-formulation-magnetohydrodynamic-wave-propagation-fire-hose-mirror-instabilities-harris-type-current-sheets"><span>General formulation for magnetohydrodynamic wave propagation, fire-hose, and mirror instabilities in Harris-type <span class="hlt">current</span> <span class="hlt">sheets</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Hau, L.-N.; Department of Physics, National Central University, Jhongli, Taiwan; Lai, Y.-T.</p> <p></p> <p>Harris-type <span class="hlt">current</span> <span class="hlt">sheets</span> with the magnetic field model of B-vector=B{sub x}(z)x-caret+B{sub y}(z)y-caret have many important applications to space, astrophysical, and laboratory plasmas for which the temperature or pressure usually exhibits the gyrotropic form of p{r_reversible}=p{sub Parallel-To }b-caretb-caret+p{sub Up-Tack }(I{r_reversible}-b-caretb-caret). Here, p{sub Parallel-To} and p{sub Up-Tack} are, respectively, to be the pressure component along and perpendicular to the local magnetic field, b-caret=B-vector/B. This study presents the general formulation for magnetohydrodynamic (MHD) wave propagation, fire-hose, and mirror instabilities in general Harris-type <span class="hlt">current</span> <span class="hlt">sheets</span>. The wave equations are expressed in terms of the four MHD characteristic speeds of fast, intermediate, slow, and cuspmore » waves, and in the local (k{sub Parallel-To },k{sub Up-Tack },z) coordinates. Here, k{sub Parallel-To} and k{sub Up-Tack} are, respectively, to be the wave vector along and perpendicular to the local magnetic field. The parameter regimes for the existence of discrete and resonant modes are identified, which may become unstable at the local fire-hose and mirror instability thresholds. Numerical solutions for discrete eigenmodes are shown for stable and unstable cases. The results have important implications for the anomalous heating and stability of thin <span class="hlt">current</span> <span class="hlt">sheets</span>.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22490117-existence-three-dimensional-ideal-magnetohydrodynamic-equilibria-current-sheets','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22490117-existence-three-dimensional-ideal-magnetohydrodynamic-equilibria-current-sheets"><span>Existence of three-dimensional ideal-magnetohydrodynamic equilibria with <span class="hlt">current</span> <span class="hlt">sheets</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Loizu, J.; Princeton Plasma Physics Laboratory, PO Box 451, Princeton, New Jersey 08543; Hudson, S. R.</p> <p>2015-09-15</p> <p>We consider the linear and nonlinear ideal plasma response to a boundary perturbation in a screw pinch. We demonstrate that three-dimensional, ideal-MHD equilibria with continuously nested flux-surfaces and with discontinuous rotational-transform across the resonant rational-surfaces are well defined and can be computed both perturbatively and using fully nonlinear equilibrium calculations. This rescues the possibility of constructing MHD equilibria with <span class="hlt">current</span> <span class="hlt">sheets</span> and continuous, smooth pressure profiles. The results predict that, even if the plasma acts as a perfectly conducting fluid, a resonant magnetic perturbation can penetrate all the way into the center of a tokamak without being shielded at themore » resonant surface.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19950046666&hterms=balance+sheet&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dbalance%2Bsheet','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19950046666&hterms=balance+sheet&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dbalance%2Bsheet"><span>Interpretation of high-speed flows in the plasma <span class="hlt">sheet</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Chen, C. X.; Wolf, R. A.</p> <p>1993-01-01</p> <p>Pursuing an idea suggested by Pontius and Wolf (1990), we propose that the `bursty bulk flows' observed by Baumjohann et al. (1990) and Angelopoulos et al. (1992) are `bubbles' in the Earth's plasma <span class="hlt">sheet</span>. Specifically, they are flux tubes that have lower values of pV(exp 5/3) than their neighbors, where p is the thermal pressure of the particles and V is the volume of a tube containing one unit of magnetic flux. Whether they are created by reconnection or some other mechanism, the bubbles are propelled earthward by a magnetic buoyancy force, which is related to the interchange instability. Most of the major observed characteristics of the bursty bulk flows can be interpreted naturally in terms of the bubble picture. We propose a new `stratified fluid' picture of the plasma <span class="hlt">sheet</span>, based on the idea that bubbles constitute the crucial transport mechanism. Results from simple mathematical models of plasma <span class="hlt">sheet</span> transport support the idea that bubbles can resolve the pressure balance inconsistency, particularly in cases where plasma <span class="hlt">sheet</span> ions are lost by gradient/curvature drift out the sides of the <span class="hlt">tail</span> or bubbles are generated by reconnection in the middle of plasma <span class="hlt">sheet</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19930040399&hterms=2441&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3D%2526%25232441','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19930040399&hterms=2441&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3D%2526%25232441"><span>Limits on plasma anisotropy in a <span class="hlt">tail</span>-like magnetic field</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hill, T. W.; Voigt, G.-H.</p> <p>1992-01-01</p> <p>The condition of magnetohydrostatic equilibrium implies tight constraints on the degree of anisotropy that is supportable in a magnetotail field geometry. If the plasma pressure tensor is assumed to be gyrotropic at the <span class="hlt">tail</span> midplane (z = 0), then equilibrium requires that it also be nearly isotropic there, with P-perpendicular sub 0/P-parallel sub 0 in the range 1 +/- delta square, where delta of about 0.1 is the ratio of the normal field component at the symmetry plane to the field strength in the <span class="hlt">tail</span> lobe. The upper and the lower limits are essentially equivalent, respectively, to the marginal mirror and firehose stability conditions evaluated at z = 0, which have been invoked previously to limit the degree of anisotropy in the plasma <span class="hlt">sheet</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016ApJ...832...16R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016ApJ...832...16R"><span><span class="hlt">Current</span> <span class="hlt">Sheet</span> Structures Observed by the TESIS EUV Telescope during a Flux Rope Eruption on the Sun</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Reva, A. A.; Ulyanov, A. S.; Kuzin, S. V.</p> <p>2016-11-01</p> <p>We use the TESIS EUV telescope to study the <span class="hlt">current</span> <span class="hlt">sheet</span> signatures observed during flux rope eruption. The special feature of the TESIS telescope was its ability to image the solar corona up to a distance of 2 {R}⊙ from the Sun’s center in the Fe 171 Å line. The Fe 171 Å line emission illuminates the magnetic field lines, and the TESIS images reveal the coronal magnetic structure at high altitudes. The analyzed coronal mass ejection (CME) had a core with a spiral—flux rope—structure. The spiral shape indicates that the flux rope radius varied along its length. The flux rope had a complex temperature structure: cold legs (70,000 K, observed in He 304 Å line) and a hotter core (0.7 MK, observed in Fe 171 Å line). Such a structure contradicts the common assumption that the CME core is a cold prominence. When the CME impulsively accelerated, a dark double Y-structure appeared below the flux rope. The Y-structure timing, location, and morphology agree with the previously performed MHD simulations of the <span class="hlt">current</span> <span class="hlt">sheet</span>. We interpreted the Y-structure as a hot envelope of the <span class="hlt">current</span> <span class="hlt">sheet</span> and hot reconnection outflows. The Y-structure had a thickness of 6.0 Mm. Its length increased over time from 79 Mm to more than 411 Mm.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19790038352&hterms=plasma+focus&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dplasma%2Bfocus','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19790038352&hterms=plasma+focus&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dplasma%2Bfocus"><span>Investigation of a staged plasma-focus apparatus. [pinch construction and <span class="hlt">current</span> <span class="hlt">sheet</span> dynamics investigation</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Lee, J. H.; Mcfarland, D. R.; Harries, W. L.</p> <p>1978-01-01</p> <p>A new staged plasma-focus geometry combining two Mather-type plasma-focus guns was constructed, and the <span class="hlt">current-sheet</span> dynamics were investigated. The production of simultaneous pairs of plasma foci was achieved. The intensities of X-ray and fusion-neutron emission were measured and found to agree with the scaling law for a plasma focus. Advantages of this new geometry include the possibility of using plasma-focus type pinches in multiple arrays at power levels beyond the validity regime of the <span class="hlt">current</span> scaling law for a single gun.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JGRA..122..258C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JGRA..122..258C"><span>Planetary period modulations of Saturn's magnetotail <span class="hlt">current</span> <span class="hlt">sheet</span>: A simple illustrative mathematical model</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cowley, S. W. H.; Provan, G.; Hunt, G. J.; Jackman, C. M.</p> <p>2017-01-01</p> <p>We mathematically model the modulation effects on Saturn's equatorial magnetotail and magnetodisk <span class="hlt">current</span> <span class="hlt">sheet</span> produced by the combined magnetic field perturbations of the northern and southern planetary period oscillation (PPO) systems, specifically north-south displacements associated with the radial perturbation field and thickness modulations associated with the colatitudinal perturbation field. Since the phasing of the two PPO systems is taken to be related to the radial field perturbations, while the relative phasing of the colatitudinal perturbations is opposite for the two systems, the north-south oscillations reinforce when the two PPO systems are in phase, while the thickening-thinning effects reinforce when they are in antiphase. For intermediate relative phases we show that when the northern PPO system leads the southern the <span class="hlt">sheet</span> is thicker when moving south to north than when moving north to south, while when the northern PPO system lags the southern the <span class="hlt">sheet</span> is thicker when moving north to south than when moving south to north, thus leading to sawtooth profiles in the radial field for near-equatorial observers, of opposite senses in the two cases. Given empirically determined modulation amplitudes, the maximum sawtooth effect is found to be small when one system dominates the other, but becomes clear when the amplitude of one system lies within a factor of 2 of the other.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/5314023-cross-field-current-instability-substorm-expansions','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/5314023-cross-field-current-instability-substorm-expansions"><span>A cross-field <span class="hlt">current</span> instability for substorm expansions</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Lui, A.T.Y.; Chang, C.L.; Mankofsky, A.</p> <p>1991-07-01</p> <p>The authors investigate a cross-field <span class="hlt">current</span> instability (CFCI) as a candidate for <span class="hlt">current</span> disruption during substorm expansions. The numerical solution of the linear dispersion equation indicates that (1) the proposed instability can occur at the inner edge or the midsection of the neutral <span class="hlt">sheet</span> just prior to the substorm expansion onset although the former environment is found more favorable at the same drift speed scaled to the ion thermal speed, (2) the computed growth time is comparable to the substorm onset time, and (3) the excited waves have a mixed polarization with frequencies near the ion gyrofrequency at the innermore » edge and near the lower hybrid frequency in the midtail region. On the basis of this analysis, they propose a substorm development scenario in which plasma <span class="hlt">sheet</span> thinning during the substorm growth phase leads to an enhancement in the relative drift between ions and electrons. This results in the neutral <span class="hlt">sheet</span> being susceptible to the CHCI and initiates the diversion of the cross-<span class="hlt">tail</span> <span class="hlt">current</span> through the ionosphere. Whether or not a substorm <span class="hlt">current</span> wedge is ultimately formed is regulated by the ionospheric condition. A large number of substorm features can be readily understood with the proposed scheme. These include (1) precursory activities (pseudobreakups) prior to substorm onset, (2) substorm initiation region to be spatially localized, (3) three different solar wind conditions for substorm occurence, (4) skew towards evening local times for substorm onset locations, (5) different acceleration characteristics between ions and electrons, (6) tailward spreading of <span class="hlt">current</span> disruption region after substorm onset, and (7) local time expansion of substorm <span class="hlt">current</span> wedge with possible discrete westward jump for the evening expansion.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19920033163&hterms=magnetic+cooling&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dmagnetic%2Bcooling','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19920033163&hterms=magnetic+cooling&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dmagnetic%2Bcooling"><span>A numerical simulation of magnetic reconnection and radiative cooling in line-tied <span class="hlt">current</span> <span class="hlt">sheets</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Forbes, T. G.; Malherbe, J. M.</p> <p>1991-01-01</p> <p>Radiative MHD equations are used for an optically thin plasma to carry out a numerical experiment related to the formation of 'postflare' loops. The numerical experiment starts with a <span class="hlt">current</span> <span class="hlt">sheet</span> that is in mechanical and thermal equilibrium but is unstable to both tearing-mode and thermal-condensation instabilities. The <span class="hlt">current</span> <span class="hlt">sheet</span> is line-tied at one end to a photospheric-like boundary and evolves asymmetrically. The effects of thermal conduction, resistivity variation, and gravity are ignored. In general, reconnection in the nonlinear stage of the tearing-mode instability can strongly affect the onset of condensations unless the radiative-cooling time scale is much smaller than the tearing-mode time scale. When the ambient plasma is less than 0.2, the reconnection enters a regime where the outflow from the reconnection region is supermagnetosonic with respect to the fast-mode wave speed. In the supermagnetosonic regime the most rapidly condensing regions occur downstream of a fast-mode shock that forms where the outflow impinges on closed loops attached to the photospheric-like boundary. A similar shock-induced condensation might occur during the formation of 'postflare' loops.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018AIPA....8e6122H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018AIPA....8e6122H"><span>Investigation of the magnetic properties of Si-gradient steel <span class="hlt">sheet</span> by comparison with 6.5%Si steel <span class="hlt">sheet</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hiratani, T.; Zaizen, Y.; Oda, Y.; Yoshizaki, S.; Senda, K.</p> <p>2018-05-01</p> <p>In this study, we investigated the magnetic properties of Si-gradient steel <span class="hlt">sheet</span> produced by CVD (chemical vapor deposition) siliconizing process, comparing with 6.5% Si steel <span class="hlt">sheet</span>. The Si-gradient steel <span class="hlt">sheet</span> having silicon concentration gradient in the thickness direction, has larger hysteresis loss and smaller eddy <span class="hlt">current</span> loss than the 6.5% Si steel <span class="hlt">sheet</span>. In such a loss configuration, the iron loss of the Si-gradient steel <span class="hlt">sheet</span> becomes lower than that of the 6.5% Si steel <span class="hlt">sheet</span> at high frequencies. The experiment suggests that tensile stress is formed at the surface layer and compressive stress is formed at the inner layer in the Si gradient steel <span class="hlt">sheet</span>. The magnetic anisotropy is induced by the internal stress and it is considered to affect the magnetization behavior of the Si-gradient steel <span class="hlt">sheet</span>. The small eddy <span class="hlt">current</span> loss of Si-gradient steel <span class="hlt">sheet</span> can be explained as an effect of magnetic flux concentration on the surface layer.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/2268377','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/2268377"><span>Use of a spread <span class="hlt">sheet</span> to calculate the <span class="hlt">current</span>-density distribution produced in human and rat models by low-frequency electric fields.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hart, F X</p> <p>1990-01-01</p> <p>The <span class="hlt">current</span>-density distribution produced inside irregularly shaped, homogeneous human and rat models by low-frequency electric fields is obtained by a two-stage finite-difference procedure. In the first stage the model is assumed to be equipotential. Laplace's equation is solved by iteration in the external region to obtain the capacitive-<span class="hlt">current</span> densities at the model's surface elements. These values then provide the boundary conditions for the second-stage relaxation solution, which yields the internal <span class="hlt">current</span>-density distribution. Calculations were performed with the Excel spread-<span class="hlt">sheet</span> program on a Macintosh-II microcomputer. A spread <span class="hlt">sheet</span> is a two-dimensional array of cells. Each cell of the <span class="hlt">sheet</span> can represent a square element of space. Equations relating the values of the cells can represent the relationships between the potentials in the corresponding spatial elements. Extension to three dimensions is readily made. Good agreement was obtained with <span class="hlt">current</span> densities measured on human models with both, one, or no legs grounded and on rat models in four different grounding configurations. The results also compared well with predictions of more sophisticated numerical analyses. Spread <span class="hlt">sheets</span> can provide an inexpensive and relatively simple means to perform good, approximate dosimetric calculations on irregularly shaped objects.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active"><span>12</span></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_12 --> <div id="page_13" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="241"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMNH33B0257C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMNH33B0257C"><span>Assessing Risks of Mine <span class="hlt">Tailing</span> Dam Failures</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Concha Larrauri, P.; Lall, U.</p> <p>2017-12-01</p> <p>The consequences of <span class="hlt">tailings</span> dam failures can be catastrophic for communities and ecosystems in the vicinity of the dams. The failure of the Fundão <span class="hlt">tailings</span> dam at the Samarco mine in 2015 killed 19 people with severe consequences for the environment. The financial and legal consequences of a <span class="hlt">tailings</span> dam failure can also be significant for the mining companies. For the Fundão <span class="hlt">tailings</span> dam, the company had to pay 6 billion dollars in fines and twenty-one executives were charged with qualified murder. There are tenths of thousands of active, inactive, and abandoned <span class="hlt">tailings</span> dams in the world and there is a need to better understand the hazards posed by these structures to downstream populations and ecosystems. A challenge to assess the risks of <span class="hlt">tailings</span> dams in a large scale is that many of them are not registered in publicly available databases and there is little information about their <span class="hlt">current</span> physical state. Additionally, hazard classifications of <span class="hlt">tailings</span> dams - common in many countries- tend to be subjective, include vague parameter definitions, and are not always updated over time. Here we present a simple methodology to assess and rank the exposure to <span class="hlt">tailings</span> dams using ArcGIS that removes subjective interpretations. The method uses basic information such as <span class="hlt">current</span> dam height, storage volume, topography, population, land use, and hydrological data. A hazard rating risk was developed to compare the potential extent of the damage across dams. This assessment provides a general overview of what in the vicinity of the <span class="hlt">tailings</span> dams could be affected in case of a failure and a way to rank <span class="hlt">tailings</span> dams that is directly linked to the exposure at any given time. One hundred <span class="hlt">tailings</span> dams in Minas Gerais, Brazil were used for the test case. This ranking approach could inform the risk management strategy of the <span class="hlt">tailings</span> dams within a company, and when disclosed, it could enable shareholders and the communities to make decisions on the risks they are taking.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002JGRA..107.1136R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002JGRA..107.1136R"><span>Modeling the heliospheric <span class="hlt">current</span> <span class="hlt">sheet</span>: Solar cycle variations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Riley, Pete; Linker, J. A.; Mikić, Z.</p> <p>2002-07-01</p> <p>In this report we employ an empirically driven, three-dimensional MHD model to explore the evolution of the heliospheric <span class="hlt">current</span> <span class="hlt">sheet</span> (HCS) during the course of the solar cycle. We compare our results with a simpler ``constant-speed'' approach for mapping the HCS outward into the solar wind to demonstrate that dynamic effects can substantially deform the HCS in the inner heliosphere (<~5 AU). We find that these deformations are most pronounced at solar minimum and become less significant at solar maximum, when interaction regions are less effective. Although solar maximum is typically associated with transient, rather than corotating, processes, we show that even under such conditions, the HCS can maintain its structure over the course of several solar rotations. While the HCS may almost always be topologically equivalent to a ``ballerina skirt,'' we discuss an interval approaching the maximum of solar cycle 23 (Carrington rotations 1960 and 1961) when the shape would be better described as ``conch shell''-like. We use Ulysses magnetic field measurements to support the model results.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/867027','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/867027"><span>Electromagnetic augmentation for casting of thin metal <span class="hlt">sheets</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Hull, John R.</p> <p>1989-01-01</p> <p>Thin metal <span class="hlt">sheets</span> are cast by magnetically levitating molten metal deposited in a mold within a ferromagnetic yoke and between AC conducting coils and linearly displacing the magnetically levitated liquid metal while it is being cooled by the water-cooled walls of the mold to form a solid metal <span class="hlt">sheet</span>. A conducting shield is electrically coupled to the molten metal <span class="hlt">sheet</span> to provide a return path for eddy <span class="hlt">currents</span> induced in the metal <span class="hlt">sheet</span> by the <span class="hlt">current</span> in the AC conducting coils. In another embodiment, a DC conducting coil is coupled to the metal <span class="hlt">sheet</span> for providing a direct <span class="hlt">current</span> therein which interacts with the magnetic field to levitate the moving metal <span class="hlt">sheet</span>. Levitation of the metal <span class="hlt">sheet</span> in both molten and solid forms reduces its contact pressure with the mold walls while maintaining sufficient engagement therebetween to permit efficient conductive cooling by the mold through which a coolant fluid may be circulated. The magnetic fields associated with the <span class="hlt">currents</span> in the aforementioned coils levitate the molten metal <span class="hlt">sheet</span> while the mold provides for its lateral and vertical confinement. A leader <span class="hlt">sheet</span> having electromagnetic characteristics similar to those of the molten metal <span class="hlt">sheet</span> is used to start the casing process and precedes the molten metal <span class="hlt">sheet</span> through the yoke/coil arrangement and mold and forms a continuous <span class="hlt">sheet</span> therewith. The yoke/coil arrangement may be either U-shaped with a single racetrack coil or may be rectangular with a pair of spaced, facing bedstead coils.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003GeoRL..30.2135M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003GeoRL..30.2135M"><span>Bashful ballerina: Southward shifted heliospheric <span class="hlt">current</span> <span class="hlt">sheet</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mursula, K.; Hiltula, T.</p> <p>2003-11-01</p> <p>It is known since long [Rosenberg and Coleman, 1969] that one of the two sectors of the interplanetary magnetic field (IMF) observed at the Earth's orbit dominates at high heliographic latitudes during solar minimum times, reflecting the poloidal structure of the global solar magnetic field at these times. Here we find that while this latitudinal variation of the dominant IMF sector around the solar equator is valid for both solar hemispheres during the last four solar minima covered by direct observations, it is systematically more strongly developed in the northern heliographic hemisphere. This implies that the average heliospheric <span class="hlt">current</span> <span class="hlt">sheet</span> is shifted or coned southward during solar minimum times, suggesting that the temporary southward shift of the heliosheet found earlier by Ulysses observations in 1995 is a persistent pattern. This also implies that the open solar magnetic field is north-south asymmetric at these times, suggesting that the solar dynamo has an asymmetric component. Accordingly, the Sun with the heliosheet is like a bashful ballerina who is repeatedly trying to push her excessively high flaring skirt downward. However, the effective shift at 1 AU is only a few degrees, allowing the Rosenberg-Coleman rule to be valid, on an average, in both hemispheres during solar minima.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004cosp...35.2805M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004cosp...35.2805M"><span>Bashful Ballerina: Southward shifted Heliospheric <span class="hlt">Current</span> <span class="hlt">Sheet</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mursula, K.; Hiltula, T.</p> <p></p> <p>It is known since long (Rosenberg and Coleman, 1969) that one of the two sectors of the interplanetary magnetic field (IMF) observed at the Earth's orbit dominates at high heliographic latitudes during solar minimum times, reflecting the poloidal structure of the global solar magnetic field at these times. Here we find that while this latitudinal variation of the dominant IMF sector around the solar equator is valid for both solar hemispheres during the last four solar minima covered by direct observations, it is systematically more strongly developed in the northern heliographic hemisphere. This implies that the average heliospheric <span class="hlt">current</span> <span class="hlt">sheet</span> is shifted or coned southward during solar minimum times, suggesting that the temporary southward shift of the heliosheet found earlier by Ulysses observations in 1995 is a persistent pattern. This also implies that the open solar magnetic field is north-south asymmetric at these times, suggesting that the solar dynamo has an asymmetric component. Accordingly, the Sun with the heliosheet is like a bashful ballerina who is repeatedly trying to push her excessively high flaring skirt downward. However, the effective shift at 1 AU is only a few degrees, allowing the Rosenberg-Coleman rule to be valid, on an average, in both hemispheres during solar minima.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19950046659&hterms=dropout&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Ddropout','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19950046659&hterms=dropout&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Ddropout"><span>Structured plasma <span class="hlt">sheet</span> thinning observed by Galileo and 1984-129</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Reeves, G. D.; Belian, R. D.; Fritz, T. A.; Kivelson, M. G.; Mcentire, R. W.; Roelof, E. C.; Wilken, B.; Williams, D. J.</p> <p>1993-01-01</p> <p>On December 8, 1990, the Galileo spacecraft used the Earth for a gravity assist on its way to Jupiter. Its trajectory was such that it crossed geosynchronous orbit at approximately local midnight between 1900 and 2000 UT. At the same time, spacecraft 1984-129 was also located at geosynchronous orbit near local midnight. Several flux dropout events were observed when the two spacecraft were in the near-Earth plasma <span class="hlt">sheet</span> in the same local time sector. Flux dropout events are associated with plasma <span class="hlt">sheet</span> thinning in the near-profile of the near-Earth plasma <span class="hlt">sheet</span> while 1984-129 provided an azimuthal profile. With measurements from these two spacecraft we can distinguish between spatial structures and temporal change. Our observations confirm that the geosynchronous flux dropout events are consistent with plasma <span class="hlt">sheet</span> thinning which changes the spacecraft's magnetic connection from the trapping region to the more distant plasma <span class="hlt">sheet</span>. However, for this period, thinning occurred on two spatial and temporal scales. The geosynchronous dropouts were highly localized phenomena of 30 min duration superimposed on a more global reconfiguration of the <span class="hlt">tail</span> lasting approximately 4 hours.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19880059413&hterms=technologies+sausages&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dtechnologies%2Bsausages','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19880059413&hterms=technologies+sausages&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dtechnologies%2Bsausages"><span>Streaming sausage, kink and tearing instabilities in a <span class="hlt">current</span> <span class="hlt">sheet</span> with applications to the earth's magnetotail</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Lee, L. C.; Wang, S.; Wei, C. Q.; Tsurutani, B. T.</p> <p>1988-01-01</p> <p>This paper investigates the growth rates and eigenmode structures of the streaming sausage, kink, and tearing instabilities in a <span class="hlt">current</span> <span class="hlt">sheet</span> with a super-Alfvenic flow. The growth rates and eigenmode structures are first considered in the ideal incompressible limit by using a four-layer model, as well as a more realistic case in which all plasma parameters and the magnetic field vary continuously along the direction perpendicular to the magnetic field and plasma flow. An initial-value method is applied to obtain the growth rate and eigenmode profiles of the fastest growing mode, which is either the sausage mode or kink mode. It is shown that, in the earth's magnetotail, where super-Alfvenic plasma flows are observed in the plasma <span class="hlt">sheet</span> and the ratio between the plasma and magnetic pressures far away from the <span class="hlt">current</span> layer is about 0.1-0.3 in the lobes, the streaming sausage and streaming tearing instabilities, but not kink modes, are likely to occur.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19920015552','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19920015552"><span>FDTD modeling of thin impedance <span class="hlt">sheets</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Luebbers, Raymond; Kunz, Karl</p> <p>1991-01-01</p> <p>Thin <span class="hlt">sheets</span> of resistive or dielectric material are commonly encountered in radar cross section calculations. Analysis of such <span class="hlt">sheets</span> is simplified by using <span class="hlt">sheet</span> impedances. It is shown that <span class="hlt">sheet</span> impedances can be modeled easily and accurately using Finite Difference Time Domain (FDTD) methods. These <span class="hlt">sheets</span> are characterized by a discontinuity in the tangential magnetic field on either side of the <span class="hlt">sheet</span> but no discontinuity in tangential electric field. This continuity, or single valued behavior of the electric field, allows the <span class="hlt">sheet</span> <span class="hlt">current</span> to be expressed in terms of an impedance multiplying this electric field.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19980200977','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19980200977"><span>Nonguiding Center Motion and Substorm Effects in the Magnetotail</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Kaufmann, Richard L.; Kontodinas, Ioannis D.; Ball, Bryan M.; Larson, Douglas J.</p> <p>1997-01-01</p> <p>Thick and thin models of the middle magnetotail were developed using a consistent orbit tracing technique. It was found that <span class="hlt">currents</span> carried near the equator by groups of ions with anisotropic distribution functions are not well approximated by the guiding center expressions. The guiding center equations fail primarily because the calculated pressure tensor is not magnetic field aligned. The pressure tensor becomes field aligned as one moves away from the equator, but here there is a small region in which the guiding center equations remain inadequate because the two perpendicular components of the pressure tensor are unequal. The significance of nonguiding center motion to substorm processes then was examined. One mechanism that may disrupt a thin cross-<span class="hlt">tail</span> <span class="hlt">current</span> <span class="hlt">sheet</span> involves field changes that cause ions to begin following chaotic orbits. The lowest-altitude chaotic region, characterized by an adiabaticity parameter kappa approx. equal to 0.8, is especially important. The average cross-<span class="hlt">tail</span> particle drift is slow, and we were unable to generate a thin <span class="hlt">current</span> <span class="hlt">sheet</span> using such ions. Therefore, any process that tends to create a thin <span class="hlt">current</span> <span class="hlt">sheet</span> in a region with kappa approaching 0.8 may cause the cross-<span class="hlt">tail</span> <span class="hlt">current</span> to get so low that it becomes insufficient to support the lobes. A different limit may be important in resonant orbit regions of a thin <span class="hlt">current</span> <span class="hlt">sheet</span> because particles reach a maximum cross-<span class="hlt">tail</span> drift velocity. If the number of ions per unit length decreases as the <span class="hlt">tail</span> is stretched, this part of the plasma <span class="hlt">sheet</span> also may become unable to carry the cross-<span class="hlt">tail</span> <span class="hlt">current</span> needed to support the lobes. Thin <span class="hlt">sheets</span> are needed for both resonant and chaotic orbit mechanisms because the distribution function must be highly structured. A description of <span class="hlt">current</span> continuity is included to show how field aligned <span class="hlt">currents</span> can evolve during the transition from a two-dimensional (2-D) to a 3-D configuration.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JGRA..120.1022L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JGRA..120.1022L"><span>Acceleration of O+ from the cusp to the plasma <span class="hlt">sheet</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Liao, J.; Kistler, L. M.; Mouikis, C. G.; Klecker, B.; Dandouras, I.</p> <p>2015-02-01</p> <p>Heavy ions from the ionosphere that are accelerated in the cusp/cleft have been identified as a direct source for the hot plasma in the plasma <span class="hlt">sheet</span>. However, the details of the acceleration and transport that transforms the originally cold ions into the hot plasma <span class="hlt">sheet</span> population are not fully understood. The polar orbit of the Cluster satellites covers the main transport path of the O+ from the cusp to the plasma <span class="hlt">sheet</span>, so Cluster is ideal for tracking its velocity changes. However, because the cusp outflow is dispersed according to its velocity as it is transported to the <span class="hlt">tail</span>, due to the velocity filter effect, the observed changes in beam velocity over the Cluster orbit may simply be the result of the spacecraft accessing different spatial regions and not necessarily evidence of acceleration. Using the Cluster Ion Spectrometry/Composition Distribution Function instrument onboard Cluster, we compare the distribution function of streaming O+ in the <span class="hlt">tail</span> lobes with the initial distribution function observed over the cusp and reveal that the observations of energetic streaming O+ in the lobes around -20 RE are predominantly due to the velocity filter effect during nonstorm times. During storm times, the cusp distribution is further accelerated. In the plasma <span class="hlt">sheet</span> boundary layer, however, the average O+ distribution function is above the upper range of the outflow distributions at the same velocity during both storm and nonstorm times, indicating that acceleration has taken place. Some of the velocity increase is in the direction perpendicular to the magnetic field, indicating that the E × B velocity is enhanced. However, there is also an increase in the parallel direction, which could be due to nonadiabatic acceleration at the boundary or wave heating.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28800563','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28800563"><span>A novel polymer inclusion membrane based method for continuous clean-up of thiocyanate from gold mine <span class="hlt">tailings</span> water.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Cho, Youngsoo; Cattrall, Robert W; Kolev, Spas D</p> <p>2018-01-05</p> <p>Thiocyanate is present in gold mine <span class="hlt">tailings</span> waters in concentrations up to 1000mgL -1 and this has a serious environmental impact by not allowing water reuse in the flotation of gold ore. This significantly increases the consumption of fresh water and the amount of wastewater discharged in <span class="hlt">tailings</span> dams. At the same time thiocyanate in <span class="hlt">tailings</span> waters often leads to groundwater contamination. A novel continuous membrane-based method for the complete clean-up of thiocyanate in concentrations as high as 1000mgL -1 from its aqueous solutions has been developed. It employs a flat <span class="hlt">sheet</span> polymer inclusion membrane (PIM) of composition 70wt% PVC, 20wt% Aliquat 336 and 10wt% 1-tetradecanol which separates counter-<span class="hlt">current</span> streams of a feed thiocyanate solution and a 1M NaNO 3 receiving solution. The PIM-based system has been operated continuously for 45days with 99% separation efficiency. The volume of the receiving solution has been drastically reduced by recirculating it and continuously removing thiocyanate by precipitating it with in-situ generated Cu(I). The newly developed PIM-based thiocyanate clean-up method is environmentally friendly in terms of reagent use and inexpensive with respect to both equipment and running costs. Copyright © 2017 Elsevier B.V. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003SoPh..213..147B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003SoPh..213..147B"><span>A new Method for Determining the Interplanetary <span class="hlt">Current-Sheet</span> Local Orientation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Blanco, J. J.; Rodríguez-pacheco, J.; Sequeiros, J.</p> <p>2003-03-01</p> <p>In this work we have developed a new method for determining the interplanetary <span class="hlt">current</span> <span class="hlt">sheet</span> local parameters. The method, called `HYTARO' (from Hyperbolic Tangent Rotation), is based on a modified Harris magnetic field. This method has been applied to a pool of 57 events, all of them recorded during solar minimum conditions. The model performance has been tested by comparing both, its outputs and noise response, with these of the `classic MVM' (from Minimum Variance Method). The results suggest that, despite the fact that in many cases they behave in a similar way, there are specific crossing conditions that produce an erroneous MVM response. Moreover, our method shows a lower noise level sensitivity than that of MVM.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21492152','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21492152"><span>Secondary neurulation: Fate-mapping and gene manipulation of the neural tube in <span class="hlt">tail</span> bud.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Shimokita, Eisuke; Takahashi, Yoshiko</p> <p>2011-04-01</p> <p>The body <span class="hlt">tail</span> is a characteristic trait of vertebrates, which endows the animals with a variety of locomotive functions. During embryogenesis, the <span class="hlt">tail</span> develops from the <span class="hlt">tail</span> bud, where neural and mesodermal tissues make a major contribution. The neural tube in the <span class="hlt">tail</span> bud develops by the process known as secondary neurulation (SN), where mesenchymal cells undergo epithelialization and tubulogenesis. These processes contrast with the well known primary neurulation, which is achieved by invagination of an epithelial cell <span class="hlt">sheet</span>. In this study we have identified the origin of SN-undergoing cells, which is located caudo-medially to Hensen's node of early chicken embryo. This region is distinctly fate-mapped from <span class="hlt">tail</span>-forming mesoderm. The identification of the presumptive SN region has allowed us to target this region with exogenous genes using in ovo electroporation techniques. The SN-transgenesis has further enabled an exploration of molecular mechanisms underlying mesenchymal-to-epithelial transition during SN, where activity levels of Cdc42 and Rac1 are critical. This is the first demonstration of molecular and cellular analyses of SN, which can be performed at a high resolution separately from <span class="hlt">tail</span>-forming mesoderm. © 2011 The Authors. Journal compilation © 2011 Japanese Society of Developmental Biologists.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/7017689','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/biblio/7017689"><span>Electromagnetic augmentation for casting of thin metal <span class="hlt">sheets</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Hull, J.R.</p> <p>1987-10-28</p> <p>Thin metal <span class="hlt">sheets</span> are cast by magnetically levitating molten metal deposited in a model within a ferromagnetic yoke and between AC conducting coils and linearly displacing the magnetically levitated liquid metal while it is being cooled by the water-cooled walls of the mold to form a solid metal <span class="hlt">sheet</span>. A conducting shield is electrically coupled to the molten metal <span class="hlt">sheet</span> to provide a return path for eddy <span class="hlt">currents</span> induced in the metal <span class="hlt">sheet</span> by the <span class="hlt">current</span> in the AC conducting coils. In another embodiment, a DC conducting coil is coupled to the metal <span class="hlt">sheet</span> for providing a direct <span class="hlt">current</span> therein which interacts with the magnetic field to levitate the moving metal <span class="hlt">sheet</span>. Levitation of the metal <span class="hlt">sheet</span> in both molten and solid forms reduces its contact pressure with the mold walls while maintaining sufficient engagement therebetween to permit efficient conductive cooling by the mold through which a coolant fluid may be circulated. 8 figs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19920045476&hterms=disruption&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Ddisruption','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19920045476&hterms=disruption&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Ddisruption"><span>Radial expansion of the <span class="hlt">tail</span> <span class="hlt">current</span> disruption during substorms - A new approach to the substorm onset region</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Ohtani, S.; Kokubun, S.; Russell, C. T.</p> <p>1992-01-01</p> <p>A new method is used to examine the radial expansion of the <span class="hlt">tail</span> <span class="hlt">current</span> disruption and the substorm onset region. The expansion of the disruption region is specified by examining the time sequence (phase relationship) between the north-south component and the sun-earth component. This method is tested by applying it to the March 6, 1979, event. The phase relationship indicates that the <span class="hlt">current</span> disruption started on the earthward side of the spacecraft, and expanded tailward past the spacecraft. The method was used for 13 events selected from the ISEE magnetometer data. The results indicate that the <span class="hlt">current</span> disruption usually starts in the near-earth magnetotail and often within 15 RE from the earth.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20090006654&hterms=pathways&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dpathways','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20090006654&hterms=pathways&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dpathways"><span>Plasma <span class="hlt">Sheet</span> Circulation Pathways</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Moore, Thomas E.; Delcourt, D. C.; Slinker, S. P.; Fedder, J. A.; Damiano, P.; Lotko, W.</p> <p>2008-01-01</p> <p>Global simulations of Earth's magnetosphere in the solar wind compute the pathways of plasma circulation through the plasma <span class="hlt">sheet</span>. We address the pathways that supply and drain the plasma <span class="hlt">sheet</span>, by coupling single fluid simulations with Global Ion Kinetic simulations of the outer magnetosphere and the Comprehensive Ring <span class="hlt">Current</span> Model of the inner magnetosphere, including plasmaspheric plasmas. We find that the plasma <span class="hlt">sheet</span> is supplied with solar wind plasmas via the magnetospheric flanks, and that this supply is most effective for northward IMF. For southward IMF, the innermost plasma <span class="hlt">sheet</span> and ring <span class="hlt">current</span> region are directly supplied from the flanks, with an asymmetry of single particle entry favoring the dawn flank. The central plasma <span class="hlt">sheet</span> (near midnight) is supplied, as expected, from the lobes and polar cusps, but the near-Earth supply consists mainly of slowly moving ionospheric outflows for typical conditions. Work with the recently developed multi-fluid LFM simulation shows transport via plasma "fingers" extending Earthward from the flanks, suggestive of an interchange instability. We investigate this with solar wind ion trajectories, seeking to understand the fingering mechanisms and effects on transport rates.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.P13A1893G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.P13A1893G"><span>Multi-Component <span class="hlt">Current</span> <span class="hlt">Sheets</span> in the Martian Magnetotail. MAVEN Observations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Grigorenko, E.; Zelenyi, L. M.; Vaisberg, O. L.; Ermakov, V.; Dubinin, E.; Malova, H. V.</p> <p>2016-12-01</p> <p><span class="hlt">Current</span> <span class="hlt">sheets</span> (CSs) are the wide-spread objects in space and laboratory plasmas. The capability of CSs to maintain their stability, efficiently store and convert energy is a challenge to space physicists for many decades. Extensive studies of the CSs showed that the presence of multi-component plasma distribution can significantly affect the CS structure and dynamics. Such features like CS thinning, embedding and bifurcation are often related to the anisotropy of particle velocity distribution functions and multi-component ion composition, and they can be a source for generation of plasma instabilities and <span class="hlt">current</span> disruption/reconnection. The MAVEN mission equipped with comprehensive instrument suite allows the observations of plasma and magnetic field characteristics with a high time resolution and provides an opportunity to study different processes in the Martian plasma environment. In this work we present the analysis of the CSs observed by MAVEN in the Martian magnetotail and discuss the peculiarities of their structure in relation to the thermal/energy characteristics of different plasma components. The relation to the existing CS models is also discussed. This work is supported by Russian Science Foundation (grant Nr.16-42-01103)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AdSpR..50.1317H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AdSpR..50.1317H"><span>A statistical analysis of substorm associated <span class="hlt">tail</span> activity</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hsu, Tung-Shin; McPherron, Robert L.</p> <p>2012-11-01</p> <p>Substorm onset timing is a critical issue in magnetotail dynamics research. Solar wind energy is accumulated in the magnetosphere and the configuration of the magnetosphere evolves toward an unstable state during the growth phase. At some point, the expansion phase begins and the stored energy is released through a variety of processes that return the magnetosphere to a lower energy state. In recovery the various processes die away. Unfortunately, the ground and magnetospheric signatures of onset, i.e. energy release, can be seen both in the growth phase prior to onset and in the expansion phase after onset. Some investigators refer to each of these events as a substorm. <span class="hlt">Tail</span> observations suggest that most substorms have one event that differentiates the behavior of the <span class="hlt">tail</span> field and plasma. We refer to this time as the "main substorm onset". Each substorm associated phenomenon is timed independently and then compared with main substorm onsets. ISEE-2 <span class="hlt">tail</span> observations are used to examine the <span class="hlt">tail</span> lobe magnetic conditions associated with substorms because ISEE-2 orbit has a high inclination and frequently observes lobe field. Approximately 70 ˜ 75% of <span class="hlt">tail</span> lobe Bt and Bz change are associated with the main substorm onset. If the satellite is more than 3 Re above (below) the neutral <span class="hlt">sheet</span>, 86% (57%) of plasma pressure dropouts are associated with substorms. We interpret our results as evidence that the effect of the growth phase is to drive the magnetosphere towards instability. As it approaches global instability local regions become temporarily unstable but are rapidly quenched. Eventually one of these events develops into the global instability that releases most of the stored energy and returns the magnetosphere to a more stable configuration.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19920044562&hterms=plague&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dplague','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19920044562&hterms=plague&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dplague"><span>Weighted <span class="hlt">current</span> <span class="hlt">sheets</span> supported in normal and inverse configurations - A model for prominence observations</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Demoulin, P.; Forbes, T. G.</p> <p>1992-01-01</p> <p>A technique which incorporates both photospheric and prominence magnetic field observations is used to analyze the magnetic support of solar prominences in two dimensions. The prominence is modeled by a mass-loaded <span class="hlt">current</span> <span class="hlt">sheet</span> which is supported against gravity by magnetic fields from a bipolar source in the photosphere and a massless line <span class="hlt">current</span> in the corona. It is found that prominence support can be achieved in three different kinds of configurations: an arcade topology with a normal polarity; a helical topology with a normal polarity; and a helical topology with an inverse polarity. In all cases the important parameter is the variation of the horizontal component of the prominence field with height. Adding a line <span class="hlt">current</span> external to the prominence eliminates the nonsupport problem which plagues virtually all previous prominence models with inverse polarity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19930053280&hterms=Particles&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DZ%2BParticles','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19930053280&hterms=Particles&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DZ%2BParticles"><span>Particle orbits in model <span class="hlt">current</span> <span class="hlt">sheet</span> with a nonzero B(y) component</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Zhu, Zhongwei; Parks, George</p> <p>1993-01-01</p> <p>The problem of charged particle motions in magnetotaillike model <span class="hlt">current</span> <span class="hlt">sheets</span> is revisited with the inclusion of a nonzero dawn-dusk magnetic field component. Three cases are examined considering both trapped and escaped orbits. The results show that a nonzero B(y) component disturbs the particle orbits by destroying orbit symmetry in the phase space about the z = 0 plane. It also changes the bounce frequency of particle orbits. The presence of B(y) thus modifies the Speiser orbits, particularly near the ejection phase. The process of ejected particle such as ejection direction, ejection velocity, and pitch angles are shown to depend on the sign of the charge.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_13 --> <div id="page_14" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active"><span>14</span></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="261"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AnGeo..34..303X','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AnGeo..34..303X"><span>A statistical study on the shape and position of the magnetotail neutral <span class="hlt">sheet</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Xiao, Sudong; Zhang, Tielong; Ge, Yasong; Wang, Guoqiang; Baumjohann, Wolfgang; Nakamura, Rumi</p> <p>2016-02-01</p> <p>We study the average shape and position of the magnetotail neutral <span class="hlt">sheet</span> based on magnetic field data obtained by Cluster, Geotail, TC-1, and THEMIS from the years 1995 to 2013. All data in the aberrated GSM (geocentric solar magnetospheric) coordinate system are normalized to the same solar wind pressure 2 nPa and downtail distance X ˜ -20RE. Our results show characteristics of the neutral <span class="hlt">sheet</span>, as follows. (1) The neutral <span class="hlt">sheet</span> assumes a greater degree of curve in the YZ cross section when the dipole tilt increases, the Earth dipole tilt angle affects the neutral <span class="hlt">sheet</span> configuration not only in the YZ cross section but also in the XY cross section, and the neutral <span class="hlt">sheet</span> assumes a more significant degree of tilt in the XY cross section when the dipole tilt increases. (2) Counterclockwise twisting of the neutral <span class="hlt">sheet</span> with 3.10° is observed, looking along the downtail direction, for the positive interplanetary magnetic field (IMF) BY with a value of 3 to 8 nT, and clockwise twisting of the neutral <span class="hlt">sheet</span> with 3.37° for the negative IMF BY with a value of -8 to -3 nT, and a northward IMF can result in a greater twisting of the near-<span class="hlt">tail</span> neutral <span class="hlt">sheet</span> than southward. The above results can be a reference to the neutral <span class="hlt">sheet</span> model. Our large database also shows that the displaced ellipse model is effective to study the average shape of the neutral <span class="hlt">sheet</span> with proper parameters when the dipole tilt angle is larger (less) than 10° (-10° ).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19780046156&hterms=1079&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3D%2526%25231079','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19780046156&hterms=1079&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3D%2526%25231079"><span>Adiabatic particle motion in a nearly drift-free magnetic field - Application to the geomagnetic <span class="hlt">tail</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Stern, D. P.</p> <p>1978-01-01</p> <p>An investigation is made of the adiabatic particle motion occurring in an almost drift-free magnetic field. The dependence of the mean drift velocity on the equatorial pitch angle and the variation of the local drift velocity along the trajectories is studied. The fields considered are two-dimensional and resemble the geomagnetic <span class="hlt">tail</span>. Derivations are presented for instantaneous and average drift velocities, bounce times, longitudinal invariants, and approximations to the adiabatic Hamiltonian. As expected, the mean drift velocity is significantly smaller than the instantaneous drift velocities found at typical points on the trajectory. The slow drift indicates that particles advance in the dawn-dusk direction rather slowly in the plasma <span class="hlt">sheet</span> of the magnetospheric <span class="hlt">tail</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22660967-heating-mechanisms-low-solar-atmosphere-through-magnetic-reconnection-current-sheets','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22660967-heating-mechanisms-low-solar-atmosphere-through-magnetic-reconnection-current-sheets"><span>HEATING MECHANISMS IN THE LOW SOLAR ATMOSPHERE THROUGH MAGNETIC RECONNECTION IN <span class="hlt">CURRENT</span> <span class="hlt">SHEETS</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Ni, Lei; Lin, Jun; Roussev, Ilia I.</p> <p>2016-12-01</p> <p>We simulate several magnetic reconnection processes in the low solar chromosphere/photosphere; the radiation cooling, heat conduction and ambipolar diffusion are all included. Our numerical results indicate that both the high temperature (≳8 × 10{sup 4} K) and low temperature (∼10{sup 4} K) magnetic reconnection events can happen in the low solar atmosphere (100–600 km above the solar surface). The plasma β controlled by plasma density and magnetic fields is one important factor to decide how much the plasma can be heated up. The low temperature event is formed in a high β magnetic reconnection process, Joule heating is the mainmore » mechanism to heat plasma and the maximum temperature increase is only several thousand Kelvin. The high temperature explosions can be generated in a low β magnetic reconnection process, slow and fast-mode shocks attached at the edges of the well developed plasmoids are the main physical mechanisms to heat the plasma from several thousand Kelvin to over 8 × 10{sup 4} K. Gravity in the low chromosphere can strongly hinder the plasmoid instability and the formation of slow-mode shocks in a vertical <span class="hlt">current</span> <span class="hlt">sheet</span>. Only small secondary islands are formed; these islands, however, are not as well developed as those in the horizontal <span class="hlt">current</span> <span class="hlt">sheets</span>. This work can be applied to understand the heating mechanism in the low solar atmosphere and could possibly be extended to explain the formation of common low temperature Ellerman bombs (∼10{sup 4} K) and the high temperature Interface Region Imaging Spectrograph (IRIS) bombs (≳8 × 10{sup 4}) in the future.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011A%26A...525A..27P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011A%26A...525A..27P"><span>Evidence for a <span class="hlt">current</span> <span class="hlt">sheet</span> forming in the wake of a coronal mass ejection from multi-viewpoint coronagraph observations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Patsourakos, S.; Vourlidas, A.</p> <p>2011-01-01</p> <p>Context. Ray-like features observed by coronagraphs in the wake of coronal mass ejections (CMEs) are sometimes interpreted as the white light counterparts of <span class="hlt">current</span> <span class="hlt">sheets</span> (CSs) produced by the eruption. The 3D geometry of these ray-like features is largely unknown and its knowledge should clarify their association to the CS and place constraints on CME physics and coronal conditions. Aims: If these rays are related to field relaxation behind CMEs, therefore representing <span class="hlt">current</span> <span class="hlt">sheets</span>, then they should be aligned to the CME axis. With this study we test these important implications for the first time. Methods: An example of such a post-CME ray was observed by various coronagraphs, including these of the Sun Earth Connection Coronal and Heliospheric investigation (SECCHI) onboard the Solar Terrestrial Relations Observatory (STEREO) twin spacecraft and the Large Angle Spectrometric Coronagraph (LASCO) onboard the Solar and Heliospheric Observatory (SOHO). The ray was observed in the aftermath of a CME which occurred on 9 April 2008. The twin STEREO spacecraft were separated by about 48° on that day. This significant separation combined with a third “eye” view supplied by LASCO allow for a truly multi-viewpoint observation of the ray and of the CME. We applied 3D forward geometrical modeling to the CME and to the ray as simultaneously viewed by SECCHI-A and B and by SECCHI-A and LASCO, respectively. Results: We found that the ray can be approximated by a rectangular slab, nearly aligned with the CME axis, and much smaller than the CME in both terms of thickness and depth (≈0.05 and 0.15 R⊙ respectively). The ray electron density and temperature were substantially higher than their values in the ambient corona. We found that the ray and CME are significantly displaced from the associated post-CME flaring loops. Conclusions: The properties and location of the ray are fully consistent with the expectations of the standard CME theories for post-CME <span class="hlt">current</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19860040954&hterms=Saunders&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAuthor-Name%26N%3D0%26No%3D60%26Ntt%3DSaunders%252C%2BM','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19860040954&hterms=Saunders&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAuthor-Name%26N%3D0%26No%3D60%26Ntt%3DSaunders%252C%2BM"><span>Near-<span class="hlt">tail</span> reconnection as the cause of cometary <span class="hlt">tail</span> disconnections</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Russell, C. T.; Saunders, M. A.; Phillips, J. L.; Fedder, J. A.</p> <p>1986-01-01</p> <p>In a cometary <span class="hlt">tail</span> disconnection event the plasma <span class="hlt">tail</span> appears to separate from the coma and to accelerate away from it. As this occurs a new <span class="hlt">tail</span> begins to form. It is proposed that these disconnections arise in a manner analogous to geomagnetic substorms, i.e., by the formation of a strongly reconnecting region in the near <span class="hlt">tail</span> that forms a magnetic island in the coma and ejects the plasma <span class="hlt">tail</span> by strengthening the magnetic 'slingshot' within the <span class="hlt">tail</span>. This reconnection process may be triggered by several different processes, such as interplanetary shocks or variations in the Alfven Mach number.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011JGRA..116.6215J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011JGRA..116.6215J"><span>A statistical study of the inner edge of the electron plasma <span class="hlt">sheet</span> and the net convection potential as a function of geomagnetic activity</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jiang, F.; Kivelson, M. G.; Walker, R. J.; Khurana, K. K.; Angelopoulos, V.; Hsu, T.</p> <p>2011-06-01</p> <p>A widely accepted explanation of the location of the inner edge of the electron plasma <span class="hlt">sheet</span> and its dependence on electron energy is based on drift motions of individual particles. The boundary is identified as the separatrix between drift trajectories linking the <span class="hlt">tail</span> to the dayside magnetopause (open paths) and trajectories closed around the Earth. A statistical study of the inner edge of the electron plasma <span class="hlt">sheet</span> using THEMIS Electrostatic Analyzer plasma data from November 2007 to April 2009 enabled us to examine this model. Using a dipole magnetic field and a Volland-Stern electric field with shielding, we find that a steady state drift boundary model represents the average location of the electron plasma <span class="hlt">sheet</span> boundary and reflects its variation with the solar wind electric field in the local time region between 21:00 and 06:00, except at high activity levels. However, the model does not reproduce the observed energy dispersion of the boundaries. We have also used the location of the inner edge of the electron plasma <span class="hlt">sheet</span> to parameterize the potential drop of the <span class="hlt">tail</span> convection electric field as a function of solar wind electric field (Esw) and geomagnetic activity. The range of Esw examined is small because the data were acquired near solar minimum. For the range of values tested (meaningful statistics only for Esw < 2 mV/m), reasonably good agreement is found between the potential drop of the <span class="hlt">tail</span> convection electric field inferred from the location of the inner edge and the polar cap potential drop calculated from the model of Boyle et al. (1997).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19860049555&hterms=quasi+particle&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dquasi%2Bparticle','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19860049555&hterms=quasi+particle&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dquasi%2Bparticle"><span>Quasi-stagnant plasmoid in the middle <span class="hlt">tail</span> - A new preexpansion phase phenomenon. [in magnetosphere</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Nishida, A.; Terasawa, T.; Scholer, M.; Bame, S. J.; Zwickl, R. D.; Gloeckler, G.; Smith, E. J.</p> <p>1986-01-01</p> <p>From the analysis of ISEE 3 data it is found that a plasmoid is sometimes formed in the middle <span class="hlt">tail</span> outside the intervals of the substorm expansion phase. This plasmoid is produced by reconnection at the X-type neutral line, which is located earthward of the distant neutral line but beyond the substorm-associated near-<span class="hlt">tail</span> neutral line, and it is almost stagnant in that the associated flow speed is less than 300 km/s. The blocking effect of the distant neutral line is the most probable reason for the slow movement. The quasi-stagnant plasmoid is observed at x = -60 to - 100 earth radii for a duration of a few tens of minutes, and in about one half of the cases it is followed by the fast tailward streaming. The onset of this streaming tends to coincide with the onset of the substorm expansion phase, and this probably occurs when the reconnection at the middle-<span class="hlt">tail</span> neutral line comes close to processing the last closed field line. Intensification of the dawn-to-dusk electric field that causes the mantle plasma to reach the plasma <span class="hlt">sheet</span> boundary closer to the earth is suggested as the reason for the formation of the middle-<span class="hlt">tail</span> neutral line earthward of the distant neutral line. The effects on the energetic particle flux and relation to the near-<span class="hlt">tail</span> reconnection are also discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1918710V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1918710V"><span>A Transient Initialization Routine of the Community Ice <span class="hlt">Sheet</span> Model for the Greenland Ice <span class="hlt">Sheet</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>van der Laan, Larissa; van den Broeke, Michiel; Noël, Brice; van de Wal, Roderik</p> <p>2017-04-01</p> <p>The Community Ice <span class="hlt">Sheet</span> Model (CISM) is to be applied in future simulations of the Greenland Ice <span class="hlt">Sheet</span> under a range of climate change scenarios, determining the sensitivity of the ice <span class="hlt">sheet</span> to individual climatic forcings. In order to achieve reliable results regarding ice <span class="hlt">sheet</span> stability and assess the probability of future occurrence of tipping points, a realistic initial ice <span class="hlt">sheet</span> geometry is essential. The <span class="hlt">current</span> work describes and evaluates the development of a transient initialization routine, using NGRIP 18O isotope data to create a temperature anomaly field. Based on the latter, surface mass balance components runoff and precipitation are perturbed for the past 125k years. The precipitation and runoff fields originate from a downscaled 1 km resolution version of the regional climate model RACMO2.3 for the period 1961-1990. The result of the initialization routine is a present-day ice <span class="hlt">sheet</span> with a transient memory of the last glacial-interglacial cycle, which will serve as the future runs' initial condition.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMSM13C4183H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMSM13C4183H"><span>Exploration of a possible cause of magnetic reconfiguration/reconnection due to generation, rather than annihilation, of magnetic field in a nun-uniform thin <span class="hlt">current</span> <span class="hlt">sheet</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Huang, Y. C.; Lyu, L. H.</p> <p>2014-12-01</p> <p>Magnetic reconfiguration/reconnection plays an important role on energy and plasma transport in the space plasma. It is known that magnetic field lines on two sides of a tangential discontinuity can connect to each other only at a neutral point, where the strength of the magnetic field is equal to zero. Thus, the standard reconnection picture with magnetic field lines intersecting at the neutral point is not applicable to the component reconnection events observed at the magnetopause and in the solar corona. In our early study (Yu, Lyu, & Wu, 2011), we have shown that annihilation of magnetic field near a thin <span class="hlt">current</span> <span class="hlt">sheet</span> can lead to the formation of normal magnetic field component (normal to the <span class="hlt">current</span> <span class="hlt">sheet</span>) to break the frozen-in condition and to accelerate the reconnected plasma flux, even without the presence of a neutral point. In this study, we examine whether or not a generation, rather than annihilation, of magnetic field in a nun-uniform thin <span class="hlt">current</span> <span class="hlt">sheet</span> can also lead to reconnection of plasma flux. Our results indicate that a non-uniform enhancement of electric <span class="hlt">current</span> can yield formation of field-aligned <span class="hlt">currents</span>. The normal-component magnetic field generated by the field-aligned <span class="hlt">currents</span> can yield reconnection of plasma flux just outside the <span class="hlt">current</span>-enhancement region. The particle motion that can lead to non-uniform enhancement of electric <span class="hlt">currents</span> will be discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19860037048&hterms=Electric+current&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3DElectric%2Bcurrent','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19860037048&hterms=Electric+current&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3DElectric%2Bcurrent"><span>Observations of field-aligned <span class="hlt">currents</span>, waves, and electric fields at substorm onset</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Smits, D. P.; Hughes, W. J.; Cattell, C. A.; Russell, C. T.</p> <p>1986-01-01</p> <p>Substorm onsets, identified Pi 2 pulsations observed on the Air Force Geophysics Laboratory Magnetometer Network, are studied using magnetometer and electric field data from ISEE 1 as well as magnetometer data from the geosynchronous satellites GOES 2 and 3. The mid-latitude magnetometer data provides the means of both timing and locating the substorm onset so that the spacecraft locations with respect to the substorm <span class="hlt">current</span> systems are known. During two intervals, each containing several onsets or intensifications, ISEE 1 observed field-aligned <span class="hlt">current</span> signatures beginning simultaneously with the mid-latitude Pi 2 pulsation. Close to the earth broadband bursts of wave noise were observed in the electric field data whenever field-aligned <span class="hlt">currents</span> were detected. One onset occurred when ISEE 1 and GOES 2 were on the same field line but in opposite hemispheres. During this onset ISEE 1 and GOES 2 saw magnetic signatures which appear to be due to conjugate field-aligned <span class="hlt">currents</span> flowing out of the western end of the westward auroral electrojets. The ISEE 1 signature is of a line <span class="hlt">current</span> moving westward past the spacecraft. During the other interval, ISEE 1 was in the near-<span class="hlt">tail</span> region near the midnight meridian. Plasma data confirms that the plasma <span class="hlt">sheet</span> thinned and subsequently expanded at onset. Electric field data shows that the plasma moved in the opposite direction to the plasma <span class="hlt">sheet</span> boundary as the boundary expanded which implies that there must have been an abundant source of hot plasma present. The plasma motion was towards the center of the plasma <span class="hlt">sheet</span> and earthwards and consisted of a series of pulses rather than a steady flow.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/79171-electric-potential-moon-magnetosheath-geomagnetic-tail','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/79171-electric-potential-moon-magnetosheath-geomagnetic-tail"><span>Electric potential of the moon in the magnetosheath and in the geomagnetic <span class="hlt">tail</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Moskalenko, A.M.</p> <p>1995-03-01</p> <p>A layer of charged particles near the lunar surface is investigated. It is shown that in the magnetosheath and in the <span class="hlt">tail</span> lobes, where secondary electronic emission of lunar soil in the plasma <span class="hlt">sheet</span> is low, the electrostatic potential as a function of the height over the subsolar region of the surface is nonmonotone. As the terminator is approached, the potential becomes a negative monotone function. For most temperatures of the primary electrons that exist in the plasma <span class="hlt">sheet</span>, secondary electron emission is high. In the case of high secondary electron emission, the electric potential is nonmonotone, and the variationmore » of the potential in the double layer is determined by the secondary electron emission and varies weakly in the passage from the dark side to the bright side.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19880052817&hterms=beans&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dbeans','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19880052817&hterms=beans&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dbeans"><span>Simulation of electrostatic turbulence in the plasma <span class="hlt">sheet</span> boundary layer with electron <span class="hlt">currents</span> and bean-shaped ion beams</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Nishikawa, K.-I.; Frank, L. A.; Huang, C. Y.</p> <p>1988-01-01</p> <p>Plasma data from ISEE-1 show the presence of electron <span class="hlt">currents</span> as well as energetic ion beams in the plasma <span class="hlt">sheet</span> boundary layer. Broadband electrostatic noise and low-frequency electromagnetic bursts are detected in the plasma <span class="hlt">sheet</span> boundary layer, especially in the presence of strong ion flows, <span class="hlt">currents</span>, and steep spacial gradients in the fluxes of few-keV electrons and ions. Particle simulations have been performed to investigate electrostatic turbulence driven by a cold electron beam and/or ion beams with a bean-shaped velocity distribution. The simulation results show that the counterstreaming ion beams as well as the counterstreaming of the cold electron beam and the ion beam excite ion acoustic waves with a given Doppler-shifted real frequency. However, the effect of the bean-shaped ion velocity distributions reduces the growth rates of ion acoustic instability. The simulation results also show that the slowing down of the ion bean is larger at the larger perpendicular velocity. The wave spectra of the electric fields at some points of the simulations show turbulence generated by growing waves.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22525539-spectroscopic-observations-evolving-flare-ribbon-substructure-suggesting-origin-current-sheet-waves','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22525539-spectroscopic-observations-evolving-flare-ribbon-substructure-suggesting-origin-current-sheet-waves"><span>SPECTROSCOPIC OBSERVATIONS OF AN EVOLVING FLARE RIBBON SUBSTRUCTURE SUGGESTING ORIGIN IN <span class="hlt">CURRENT</span> <span class="hlt">SHEET</span> WAVES</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Brannon, S. R.; Longcope, D. W.; Qiu, J.</p> <p>2015-09-01</p> <p>We present imaging and spectroscopic observations from the Interface Region Imaging Spectrograph of the evolution of the flare ribbon in the SOL2014-04-18T13:03 M-class flare event, at high spatial resolution and time cadence. These observations reveal small-scale substructure within the ribbon, which manifests as coherent quasi-periodic oscillations in both position and Doppler velocities. We consider various alternative explanations for these oscillations, including modulation of chromospheric evaporation flows. Among these, we find the best support for some form of wave localized to the coronal <span class="hlt">current</span> <span class="hlt">sheet</span>, such as a tearing mode or Kelvin–Helmholtz instability.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19860048591&hterms=wind+monitor&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dwind%2Bmonitor','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19860048591&hterms=wind+monitor&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dwind%2Bmonitor"><span>Variation of cosmic rays and solar wind properties with respect to the heliospheric <span class="hlt">current</span> <span class="hlt">sheet</span>. II - Rigidity dependence of the latitudinal gradient of cosmic rays at 1 AU</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Newkirk, G., Jr.; Asbridge, J.; Lockwood, J. A.; Garcia-Munoz, M.; Simpson, J. A.</p> <p>1986-01-01</p> <p>The role which empirical determinations of the latitudinal variation of cosmic rays with respect to the <span class="hlt">current</span> <span class="hlt">sheet</span> may have in illuminating the importance of the cross-field drift of particles in the large-scale heliospheric magnetic field is discussed. Using K coronameter observations and measured solar wind speeds, the latitudinal gradients have been determined with respect to the <span class="hlt">current</span> <span class="hlt">sheet</span> for cosmic rays in four rigidity ranges. Gradients vary between approximately -2 and -50 pct/AU. The rigidity dependence of the decrease of cosmic ray flux with distance from the <span class="hlt">current</span> <span class="hlt">sheet</span> lies between the -0.72 to -0.86 power of the rigidity, with the exact dependence being determined by the definition used for the median rigidity of each monitor.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22303764-non-linear-tearing-null-point-current-sheets','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22303764-non-linear-tearing-null-point-current-sheets"><span>Non-linear tearing of 3D null point <span class="hlt">current</span> <span class="hlt">sheets</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Wyper, P. F., E-mail: peterw@maths.dundee.ac.uk; Pontin, D. I., E-mail: dpontin@maths.dundee.ac.uk</p> <p>2014-08-15</p> <p>The manner in which the rate of magnetic reconnection scales with the Lundquist number in realistic three-dimensional (3D) geometries is still an unsolved problem. It has been demonstrated that in 2D rapid non-linear tearing allows the reconnection rate to become almost independent of the Lundquist number (the “plasmoid instability”). Here, we present the first study of an analogous instability in a fully 3D geometry, defined by a magnetic null point. The 3D null <span class="hlt">current</span> layer is found to be susceptible to an analogous instability but is marginally more stable than an equivalent 2D Sweet-Parker-like layer. Tearing of the <span class="hlt">sheet</span> createsmore » a thin boundary layer around the separatrix surface, contained within a flux envelope with a hyperbolic structure that mimics a spine-fan topology. Efficient mixing of flux between the two topological domains occurs as the flux rope structures created during the tearing process evolve within this envelope. This leads to a substantial increase in the rate of reconnection between the two domains.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26045197','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26045197"><span>Submarine and deep-sea mine <span class="hlt">tailing</span> placements: A review of <span class="hlt">current</span> practices, environmental issues, natural analogs and knowledge gaps in Norway and internationally.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ramirez-Llodra, Eva; Trannum, Hilde C; Evenset, Anita; Levin, Lisa A; Andersson, Malin; Finne, Tor Erik; Hilario, Ana; Flem, Belinda; Christensen, Guttorm; Schaanning, Morten; Vanreusel, Ann</p> <p>2015-08-15</p> <p>The mining sector is growing in parallel with societal demands for minerals. One of the most important environmental issues and economic burdens of industrial mining on land is the safe storage of the vast amounts of waste produced. Traditionally, <span class="hlt">tailings</span> have been stored in land dams, but the lack of land availability, potential risk of dam failure and topography in coastal areas in certain countries results in increasing disposal of <span class="hlt">tailings</span> into marine systems. This review describes the different submarine <span class="hlt">tailing</span> disposal methods used in the world in general and in Norway in particular, their impact on the environment (e.g. hyper-sedimentation, toxicity, processes related to changes in grain shape and size, turbidity), <span class="hlt">current</span> legislation and need for future research. Understanding these impacts on the habitat and biota is essential to assess potential ecosystem changes and to develop best available techniques and robust management plans. Copyright © 2015 Elsevier Ltd. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28334283','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28334283"><span>The microbiology of oil sands <span class="hlt">tailings</span>: past, present, future.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Foght, Julia M; Gieg, Lisa M; Siddique, Tariq</p> <p>2017-05-01</p> <p>Surface mining of enormous oil sands deposits in northeastern Alberta, Canada since 1967 has contributed greatly to Canada's economy but has also received negative international attention due largely to environmental concerns and challenges. Not only have microbes profoundly affected the composition and behavior of this petroleum resource over geological time, they <span class="hlt">currently</span> influence the management of semi-solid <span class="hlt">tailings</span> in oil sands <span class="hlt">tailings</span> ponds (OSTPs) and <span class="hlt">tailings</span> reclamation. Historically, microbial impacts on OSTPs were generally discounted, but next-generation sequencing and biogeochemical studies have revealed unexpectedly diverse indigenous communities and expanded our fundamental understanding of anaerobic microbial functions. OSTPs that experienced different processing and management histories have developed distinct microbial communities that influence the behavior and reclamation of the <span class="hlt">tailings</span> stored therein. In particular, the interactions of Deltaproteobacteria and Firmicutes with methanogenic archaea impact greenhouse gas emissions, sulfur cycling, pore water toxicity, sediment biogeochemistry and densification, water usage and the trajectory of long-term mine waste reclamation. This review summarizes historical data; synthesizes <span class="hlt">current</span> understanding of microbial diversity and activities in situ and in vitro; predicts microbial effects on <span class="hlt">tailings</span> remediation and reclamation; and highlights knowledge gaps for future research. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/12546176','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/12546176"><span><span class="hlt">Tail</span> gut cyst.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Rao, G Mallikarjuna; Haricharan, P; Ramanujacharyulu, S; Reddy, K Lakshmi</p> <p>2002-01-01</p> <p>The <span class="hlt">tail</span> gut is a blind extension of the hindgut into the <span class="hlt">tail</span> fold just distal to the cloacal membrane. Remnants of this structure may form <span class="hlt">tail</span> gut cyst. We report a 14-year-old girl with <span class="hlt">tail</span> gut cyst that presented as acute abdomen. The patient recovered after cyst excision.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24241062','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24241062"><span>Telling <span class="hlt">tails</span>: selective pressures acting on investment in lizard <span class="hlt">tails</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Fleming, Patricia A; Valentine, Leonie E; Bateman, Philip W</p> <p>2013-01-01</p> <p>Caudal autotomy is a common defense mechanism in lizards, where the animal may lose part or all of its <span class="hlt">tail</span> to escape entrapment. Lizards show an immense variety in the degree of investment in a <span class="hlt">tail</span> (i.e., length) across species, with <span class="hlt">tails</span> of some species up to three or four times body length (snout-vent length [SVL]). Additionally, body size and form also vary dramatically, including variation in leg development and robustness and length of the body and <span class="hlt">tail</span>. Autotomy is therefore likely to have fundamentally different effects on the overall body form and function in different species, which may be reflected directly in the incidence of lost/regenerating <span class="hlt">tails</span> within populations or, over a longer period, in terms of relative <span class="hlt">tail</span> length for different species. We recorded data (literature, museum specimens, field data) for relative <span class="hlt">tail</span> length (n=350 species) and the incidence of lost/regenerating <span class="hlt">tails</span> (n=246 species). We compared these (taking phylogeny into account) with intrinsic factors that have been proposed to influence selective pressures acting on caudal autotomy, including body form (robustness, body length, leg development, and <span class="hlt">tail</span> specialization) and ecology (foraging behavior, physical and temporal niches), in an attempt to identify patterns that might reflect adaptive responses to these different factors. More gracile species have relatively longer <span class="hlt">tails</span> (all 350 spp., P < 0.001; also significant for five of the six families tested separately), as do longer (all species, P < 0.001; Iguanidae, P < 0.05; Lacertidae, P < 0.001; Scindidae, P < 0.001), climbing (all species, P < 0.05), and diurnal (all species, P < 0.01; Pygopodidae, P < 0.01) species; geckos without specialized <span class="hlt">tails</span> (P < 0.05); or active-foraging skinks (P < 0.05). We also found some relationships with the data for caudal autotomy, with more lost/regenerating <span class="hlt">tails</span> for nocturnal lizards (all 246 spp., P < 0.01; Scindidae, P < 0.05), larger skinks (P < 0.05), climbing geckos (P < 0</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20140002234','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20140002234"><span>Electrostatic Solitary Waves in the Solar Wind: Evidence for Instability at Solar Wind <span class="hlt">Current</span> <span class="hlt">Sheets</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Malaspina, David M.; Newman, David L.; Wilson, Lynn Bruce; Goetz, Keith; Kellogg, Paul J.; Kerstin, Kris</p> <p>2013-01-01</p> <p>A strong spatial association between bipolar electrostatic solitary waves (ESWs) and magnetic <span class="hlt">current</span> <span class="hlt">sheets</span> (CSs) in the solar wind is reported here for the first time. This association requires that the plasma instabilities (e.g., Buneman, electron two stream) which generate ESWs are preferentially localized to solar wind CSs. Distributions of CS properties (including shear angle, thickness, solar wind speed, and vector magnetic field change) are examined for differences between CSs associated with ESWs and randomly chosen CSs. Possible mechanisms for producing ESW-generating instabilities at solar wind CSs are considered, including magnetic reconnection.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active"><span>14</span></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_14 --> <div id="page_15" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="281"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19645442','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19645442"><span>Effect of double-<span class="hlt">tailed</span> surfactant architecture on the conformation, self-assembly, and processing in polypeptide-surfactant complexes.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Junnila, Susanna; Hanski, Sirkku; Oakley, Richard J; Nummelin, Sami; Ruokolainen, Janne; Faul, Charl F J; Ikkala, Olli</p> <p>2009-10-12</p> <p>This work describes the solid-state conformational and structural properties of self-assembled polypeptide-surfactant complexes with double-<span class="hlt">tailed</span> surfactants. Poly(L-lysine) was complexed with three dialkyl esters of phosphoric acid (i.e., phosphodiester surfactants), where the surfactant <span class="hlt">tail</span> branching and length was varied to tune the supramolecular architecture in a facile way. After complexation with the branched surfactant bis(2-ethylhexyl) phosphate in an aqueous solution, the polypeptide chains adopted an alpha-helical conformation. These rod-like helices self-assembled into cylindrical phases with the amorphous alkyl <span class="hlt">tails</span> pointing outward. In complexes with dioctyl phosphate and didodecyl phosphate, which have two linear n-octyl or n-dodecyl <span class="hlt">tails</span>, respectively, the polypeptide formed antiparallel beta-<span class="hlt">sheets</span> separated by alkyl layers, resulting in well-ordered lamellar self-assemblies. By heating, it was possible to trigger a partial opening of the beta-<span class="hlt">sheets</span> and disruption of the lamellar phase. After repeated heating/cooling, all of these complexes also showed a glass transition between 37 and 50 degrees C. Organic solvent treatment and plasticization by overstoichiometric amount of surfactant led to structure modification in poly(L-lysine)-dioctyl phosphate complexes, PLL(diC8)(x) (x = 1.0-3.0). Here, the alpha-helical PLL is surrounded by the surfactants and these bottle-brush-like chains self-assemble in a hexagonal cylindrical morphology. As x is increased, the materials are clearly plasticized and the degree of ordering is improved: The stiff alpha-helical backbones in a softened surfactant matrix give rise to thermotropic liquid-crystalline phases. The complexes were examined by Fourier transform infrared spectroscopy, small- and wide-angle X-ray scattering, transmission electron microscopy, differential scanning calorimetry, polarized optical microscopy, and circular dichroism.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19920048656&hterms=retreated&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dretreated','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19920048656&hterms=retreated&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dretreated"><span>Magnetic islands in the near geomagnetic <span class="hlt">tail</span> and its implications for the mechanism of 1054 UT CDAW 6 substorm</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Lin, N.; Walker, R. J.; Mcpherron, R. L.; Kivelson, M. G.</p> <p>1990-01-01</p> <p>During the 1054 UT CDAW 6 substorm event, two ISEE spacecraft observed dynamic changes in the magnetic field and in the flux of energetic particles in the near-earth plasma <span class="hlt">sheet</span>. In the substorm growth phase, the magnetic field at both ISEE spacecraft became <span class="hlt">tail</span>-like. Following expansion phase onset, two small scale magnetic islands were observed moving tailward at a velocity of about 580 km/s. The passage of these two magnetic islands was coincident with bursts of tailward streaming energetic particles. The length of the magnetic loops was estimated to have been about 2 to 3 earth radii while the height of the loops was less than 0.5 earth radii. The magnetic islands were produced by multipoint reconnection processes in the near <span class="hlt">tail</span> plasma <span class="hlt">sheet</span> which may have been associated with the formation of the near-earth neutral line and the subsequent formation of a large scale plasmoid. The near-earth neutral line retreated tailward later in the expansion phase, as suggested by the reversal of the streaming of energetic particles.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFMSM42B..07G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFMSM42B..07G"><span>Effect of an MLT dependent electron loss rate on the inner magnetosphere electrodynamics and plasma <span class="hlt">sheet</span> penetration to the ring <span class="hlt">current</span> region</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gkioulidou, M.; Wang, C.; Wing, S.; Lyons, L. R.; Wolf, R. A.; Hsu, T.</p> <p>2012-12-01</p> <p>Transport of plasma <span class="hlt">sheet</span> particles into the ring <span class="hlt">current</span> region is strongly affected by the penetrating convection electric field, which is the result of the large-scale magnetosphere-ionosphere (M-I) electromagnetic coupling. One of the main factors controlling this coupling is the ionospheric conductance. As plasma <span class="hlt">sheet</span> electrons drift earthward, they get scattered into the loss cone due to wave-particle interactions and precipitate to the ionosphere, producing auroral conductance. Realistic electron loss is thus important for modeling the (M-I) coupling and penetration of plasma <span class="hlt">sheet</span> into the inner magnetosphere. To evaluate the significance of electron loss rate, we used the Rice Convection Model (RCM) coupled with a force-balanced magnetic field to simulate plasma <span class="hlt">sheet</span> transport under different electron loss rates and under self-consistent electric and magnetic field. The plasma <span class="hlt">sheet</span> ion and electron sources for the simulations are based on the Geotail observations. Two major rates are used: different portions of i) strong pitch-angle diffusion everywhere electron loss rate (strong rate) and ii) a more realistic loss rate with its MLT dependence determined by wave activity (MLT rate). We found that the dawn-dusk asymmetry in the precipitating electron energy flux under the MLT rate, with much higher energy flux at dawn than at dusk, agrees better with statistical DMSP observations. Electrons trapped inside L ~ 8 RE can remain there for many hours under the MLT rate, while those under the strong rate get lost within minutes. Compared with the strong rate, the remaining electrons under the MLT rate cause higher conductance at lower latitudes, allowing for less efficient electric field shielding to convection enhancement, thus further earthward penetration of the plasma <span class="hlt">sheet</span> into the inner magnetosphere. Therefore, our simulation results indicate that the electron loss rate can significantly affect the electrodynamics of the ring <span class="hlt">current</span> region. Development</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006AGUFMSH31A0387H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006AGUFMSH31A0387H"><span>Influence of Heliospheric <span class="hlt">Current</span> <span class="hlt">Sheet</span> presence on geomagnetic storm originated by Magnetic Clouds.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hidalgo, M. A.; Blanco, J. J.</p> <p>2006-12-01</p> <p>It is well known the importance of Magnetic Cloud (MC) on the Magnetosphere and its influence as cause of strong geomagnetic activity, especially fast magnetic cloud. Sometimes magnetic cloud travels in solar wind close to the Heliospheric <span class="hlt">Current</span> <span class="hlt">Sheet</span> (HCS). We wonder if the HCS presence plays some role on the geomagnetic storm development. In this work we will try to respond to this question comparing the effect on the Magnetosphere of MC+HCS and MC without HCS, detected by WIND instruments. This work has been supported by the Spanish Comisión Internacional de Ciencia y Tecnología (CICYT), grant ESP2005-07290-C02-01 and ESP2006-08459 and Madrid Autonomous Community / University of Alcala grant CAM-UAH 2005/007.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016NatSR...626109J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016NatSR...626109J"><span>Infused polymers for cell <span class="hlt">sheet</span> release</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Juthani, Nidhi; Howell, Caitlin; Ledoux, Haylea; Sotiri, Irini; Kelso, Susan; Kovalenko, Yevgen; Tajik, Amanda; Vu, Thy L.; Lin, Jennifer J.; Sutton, Amy; Aizenberg, Joanna</p> <p>2016-05-01</p> <p>Tissue engineering using whole, intact cell <span class="hlt">sheets</span> has shown promise in many cell-based therapies. However, <span class="hlt">current</span> systems for the growth and release of these <span class="hlt">sheets</span> can be expensive to purchase or difficult to fabricate, hindering their widespread use. Here, we describe a new approach to cell <span class="hlt">sheet</span> release surfaces based on silicone oil-infused polydimethylsiloxane. By coating the surfaces with a layer of fibronectin (FN), we were able to grow mesenchymal stem cells to densities comparable to those of tissue culture polystyrene controls (TCPS). Simple introduction of oil underneath an edge of the <span class="hlt">sheet</span> caused it to separate from the substrate. Characterization of <span class="hlt">sheets</span> post-transfer showed that they retain their FN layer and morphology, remain highly viable, and are able to grow and proliferate normally after transfer. We expect that this method of cell <span class="hlt">sheet</span> growth and detachment may be useful for low-cost, flexible, and customizable production of cellular layers for tissue engineering.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4870626','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4870626"><span>Infused polymers for cell <span class="hlt">sheet</span> release</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Juthani, Nidhi; Howell, Caitlin; Ledoux, Haylea; Sotiri, Irini; Kelso, Susan; Kovalenko, Yevgen; Tajik, Amanda; Vu, Thy L.; Lin, Jennifer J.; Sutton, Amy; Aizenberg, Joanna</p> <p>2016-01-01</p> <p>Tissue engineering using whole, intact cell <span class="hlt">sheets</span> has shown promise in many cell-based therapies. However, <span class="hlt">current</span> systems for the growth and release of these <span class="hlt">sheets</span> can be expensive to purchase or difficult to fabricate, hindering their widespread use. Here, we describe a new approach to cell <span class="hlt">sheet</span> release surfaces based on silicone oil-infused polydimethylsiloxane. By coating the surfaces with a layer of fibronectin (FN), we were able to grow mesenchymal stem cells to densities comparable to those of tissue culture polystyrene controls (TCPS). Simple introduction of oil underneath an edge of the <span class="hlt">sheet</span> caused it to separate from the substrate. Characterization of <span class="hlt">sheets</span> post-transfer showed that they retain their FN layer and morphology, remain highly viable, and are able to grow and proliferate normally after transfer. We expect that this method of cell <span class="hlt">sheet</span> growth and detachment may be useful for low-cost, flexible, and customizable production of cellular layers for tissue engineering. PMID:27189419</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27189419','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27189419"><span>Infused polymers for cell <span class="hlt">sheet</span> release.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Juthani, Nidhi; Howell, Caitlin; Ledoux, Haylea; Sotiri, Irini; Kelso, Susan; Kovalenko, Yevgen; Tajik, Amanda; Vu, Thy L; Lin, Jennifer J; Sutton, Amy; Aizenberg, Joanna</p> <p>2016-05-18</p> <p>Tissue engineering using whole, intact cell <span class="hlt">sheets</span> has shown promise in many cell-based therapies. However, <span class="hlt">current</span> systems for the growth and release of these <span class="hlt">sheets</span> can be expensive to purchase or difficult to fabricate, hindering their widespread use. Here, we describe a new approach to cell <span class="hlt">sheet</span> release surfaces based on silicone oil-infused polydimethylsiloxane. By coating the surfaces with a layer of fibronectin (FN), we were able to grow mesenchymal stem cells to densities comparable to those of tissue culture polystyrene controls (TCPS). Simple introduction of oil underneath an edge of the <span class="hlt">sheet</span> caused it to separate from the substrate. Characterization of <span class="hlt">sheets</span> post-transfer showed that they retain their FN layer and morphology, remain highly viable, and are able to grow and proliferate normally after transfer. We expect that this method of cell <span class="hlt">sheet</span> growth and detachment may be useful for low-cost, flexible, and customizable production of cellular layers for tissue engineering.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PhRvB..95x5303R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PhRvB..95x5303R"><span><span class="hlt">Current</span>-induced nonuniform enhancement of <span class="hlt">sheet</span> resistance in A r+ -irradiated SrTi O3</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Roy, Debangsu; Frenkel, Yiftach; Davidovitch, Sagi; Persky, Eylon; Haham, Noam; Gabay, Marc; Kalisky, Beena; Klein, Lior</p> <p>2017-06-01</p> <p>The <span class="hlt">sheet</span> resistance Rs of A r+ irradiated SrTi O3 in patterns with a length scale of several microns increases significantly below ˜40 K in connection with driving <span class="hlt">currents</span> exceeding a certain threshold. The initial lower Rs is recovered upon warming with accelerated recovery around 70 and 160 K. Scanning superconducting quantum interference device microscopy shows local irreversible changes in the spatial distribution of the <span class="hlt">current</span> with a length scale of several microns. We attribute the observed nonuniform enhancement of Rs to the attraction of the charged single-oxygen and dioxygen vacancies by the crystallographic domain boundaries in SrTi O3 . The boundaries, which are nearly ferroelectric below 40 K, are polarized by the local electrical field associated with the driven <span class="hlt">current</span> and the clustered vacancies which suppress conductivity in their vicinity and yield a noticeable enhancement in the device resistance when the <span class="hlt">current</span> path width is on the order of the boundary extension. The temperatures of accelerated conductivity recovery are associated with the energy barriers for the diffusion of the two types of vacancies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA539720','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA539720"><span>A Hybrid Kinetic Model of Asymmetric Thin <span class="hlt">Current</span> <span class="hlt">Sheets</span> with Sheared Flows in a Collisionless Plasma</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>2010-12-27</p> <p>z are aligned with those of the usual Geocentric Sun - Earth (aSE) coordinates. In this frame, +x points from the Earth to the Sun , +y points out of...<span class="hlt">current</span> <span class="hlt">sheet</span> (box) in the solar wind. x, y, and z are aligned with the aSE coordinates, with +X pointing from the Earth toward the Sun , +y out of the...account the exact ion orbits and such properties as the anisotropic and nondiagonal pressure tensor and sheared ion flows. Figure 1a shows a schematic</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017APS..DPPYO6002S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017APS..DPPYO6002S"><span>Magnetic flux pile-up and ion heating in a <span class="hlt">current</span> <span class="hlt">sheet</span> formed by colliding magnetized plasma flows</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Suttle, L.; Hare, J.; Lebedev, S.; Ciardi, A.; Loureiro, N.; Niasse, N.; Burdiak, G.; Clayson, T.; Lane, T.; Robinson, T.; Smith, R.; Stuart, N.; Suzuki-Vidal, F.</p> <p>2017-10-01</p> <p>We present data from experiments carried out at the Magpie pulsed power facility, which show the detailed structure of the interaction of counter-streaming magnetized plasma flows. In our quasi-2D setup, continuous supersonic flows are produced with strong embedded magnetic fields of opposing directions. Their interaction leads to the formation of a dense and long-lasting <span class="hlt">current</span> <span class="hlt">sheet</span>, where we observe the pile-up of the magnetic flux at the <span class="hlt">sheet</span> boundary, as well as the annihilation of field inside, accompanied by an increase in plasma temperature. Spatially resolved measurements with Faraday rotation polarimetry, B-dot probes, XUV imaging, Thomson scattering and laser interferometry diagnostics show the detailed distribution of the magnetic field and other plasma parameters throughout the system. This work was supported in part by the Engineering and Physical Sciences Research Council (EPSRC) Grant No. EP/G001324/1, and by the U.S. Department of Energy (DOE) Awards No. DE-F03-02NA00057 and No. DE-SC-0001063.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AnGeo..31.1109A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AnGeo..31.1109A"><span>Profiles of electron temperature and Bz along Earth's magnetotail</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Artemyev, A. V.; Petrukovich, A. A.; Nakamura, R.; Zelenyi, L. M.</p> <p>2013-06-01</p> <p>We study the electron temperature distribution and the structure of the <span class="hlt">current</span> <span class="hlt">sheet</span> along the magnetotail using simultaneous observations from THEMIS spacecraft. We perform a statistical study of 40 crossings of the <span class="hlt">current</span> <span class="hlt">sheet</span> when the three spacecraft THB, THC, and THD were distributed along the <span class="hlt">tail</span> in the vicinity of midnight with coordinates XB \\in [-30 RE, -20 RE], XC \\in [-20 RE, -15 RE], and XD ~ -10 RE. We obtain profiles of the average electron temperature \\mlab Te\\mrab and the average magnetic field \\mlab Bz\\mrab along the <span class="hlt">tail</span>. Electron temperature and \\mlab Bz\\mrab increase towards the Earth with almost the same rates (i.e., ratio \\mlab Te\\mrab/\\mlab Bz\\mrab ≈ 2 keV/7 nT is approximately constant along the <span class="hlt">tail</span>). We also use statistics of 102 crossings of the <span class="hlt">current</span> <span class="hlt">sheet</span> from THB and THC to estimate dependence of Te and Bz distributions on geomagnetic activity. The ratio \\mlab Te \\mrab/\\mlab Bz\\mrab depends on geomagnetic activity only slightly. Additionally we demonstrate that anisotropy of the electron temperature \\mlab T∥/T⊥\\mrab ≈ 1.1 is almost constant along the <span class="hlt">tail</span> for X \\in [-30 RE, -10 RE].</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.loc.gov/pictures/collection/hh/item/ny1812.photos.351481p/','SCIGOV-HHH'); return false;" href="https://www.loc.gov/pictures/collection/hh/item/ny1812.photos.351481p/"><span>REAR PROFILE OF <span class="hlt">TAIL</span> FROM SECOND LEVEL OF <span class="hlt">TAIL</span> DOCK ...</span></a></p> <p><a target="_blank" href="http://www.loc.gov/pictures/collection/hh/">Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey</a></p> <p></p> <p></p> <p>REAR PROFILE OF <span class="hlt">TAIL</span> FROM SECOND LEVEL OF <span class="hlt">TAIL</span> DOCK STAND, SHOWING AIRCRAFT NUMBER (319), HORIZONTAL STABILIZER, <span class="hlt">TAIL</span> CONE AND COOLING CTS FOR THE AUXILIARY POWER UNIT (APU), MECHANIC PAUL RIDEOUT IS LOWERING THE BALANCE PANELS ON THE STABILIZERS FOR LUBRICATION AND INSPECTION. - Greater Buffalo International Airport, Maintenance Hangar, Buffalo, Erie County, NY</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010JGRA..115.7212H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010JGRA..115.7212H"><span>Equatorward moving arcs and substorm onset</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Haerendel, Gerhard</p> <p>2010-07-01</p> <p>Key observations of phenomena during the growth phase of a substorm are being reviewed with particular attention to the equatorward motion of the hydrogen and electron arcs. The dynamic role of the electron, the so-called growth phase arc, is analyzed. It is part of a <span class="hlt">current</span> system of type II that is instrumental in changing the dominantly equatorward convection from the polar cap into a sunward convection along the auroral oval. A quantitative model of the arc and associated <span class="hlt">current</span> system allows determining the energy required for the flow change. It is suggested that high-β plasma outflow from the central <span class="hlt">current</span> <span class="hlt">sheet</span> of the <span class="hlt">tail</span> creates the <span class="hlt">current</span> generator. Assessment of the energy supplied in this process proves its sufficiency for driving the arc system. The equatorward motion of the arcs is interpreted as a manifestation of the shrinkage of the near-Earth transition region (NETR) between the dipolar magnetosphere and the highly stretched <span class="hlt">tail</span>. This shrinkage is caused by returning magnetic flux to the dayside magnetosphere as partial replacement of the flux eroded by frontside reconnection. As the erosion of the NETR is proceeding, more and more magnetic flux is demanded from the central <span class="hlt">current</span> <span class="hlt">sheet</span> of the near-Earth <span class="hlt">tail</span> until highly accelerated plasma outflow causes the <span class="hlt">current</span> <span class="hlt">sheet</span> to collapse. Propagation of the collapse along the <span class="hlt">tail</span> triggers reconnection and initiates the substorm.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19950038807&hterms=Xx&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DXx','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19950038807&hterms=Xx&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DXx"><span>Comparison of the plasma <span class="hlt">tails</span> of four comets: P/Halley, Okazaki-Levy-Rudenko, Austin, and Levy</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Farnham, Tony L.; Meech, Karen J.</p> <p>1994-01-01</p> <p>Photographic and charge coupled device (CCD) plasma <span class="hlt">tail</span> observations are compared for four comets: P/Halley (22 nights in 1985/1986), Okazaki-Levy-Rudenko 1989 XIX (1989 December 2), Austin 1990 V (nine nights in 1990), and Levy 1990 XX (two nights in 1991). We present a discussion of several image-processing techniques used to enhance the visibility of the plasma <span class="hlt">tail</span> features in order to measure velocities, accelerations, and position angles. The data are used to assess the validity of various physical mechanisms proposed to explain plasma <span class="hlt">tail</span> phenomena. Seven disconnection events were observed in the comet P/Halley data, two in the Austin data, and none for the other comets. Analysis of these data suggests that while the crossing of the solar neutral <span class="hlt">sheet</span> (the sector boundary) is a prominent factor in the production of a disconnection event, it is likely that several mechanisms are at work. A sector boundary crossing has been ruled out as the cause of either the 1986 April 26 P/Halley disconnection or the 1990 May 5/6 Austin disconnection. The motions of the disconnection events, knots, and condensations in the <span class="hlt">tails</span> were seen to increase from 30-60 km/s near the nucleus (within 10(exp 6) km) to 80-100 km/s at 10(exp 7) km, consistent with either bulk motion or Alfven waves. Distinguishing between the two cases is not possible with these data. It was found that although the <span class="hlt">tail</span> ray rotation rate slows as the ray approaches the <span class="hlt">tail</span> axis, it is not a good indicator of the solar wind speed. Historical plasma <span class="hlt">tail</span> data are also used to look for clues as to why some comets form well-developed plasma <span class="hlt">tails</span> and others do not.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/866298','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/866298"><span>Horizontal electromagnetic casting of thin metal <span class="hlt">sheets</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Hull, John R.; Lari, Robert J.; Praeg, Walter F.; Turner, Larry R.</p> <p>1987-01-01</p> <p>Thin metal <span class="hlt">sheets</span> are cast by magnetically suspending molten metal deposited within a ferromagnetic yoke and between AC conducting coils and linearly displacing the magnetically levitated liquid metal while it is being cooled to form a solid metal <span class="hlt">sheet</span>. Magnetic flux increases as the molten metal <span class="hlt">sheet</span> moves downward and decreases as the molten metal <span class="hlt">sheet</span> moves upward to stabilize the <span class="hlt">sheet</span> and maintain it in equilibrium as it is linearly displaced and solidified by cooling gases. A conducting shield is electrically coupled to the molten metal <span class="hlt">sheet</span> by means of either metal <span class="hlt">sheet</span> engaging rollers or brushes on the solidified metal, and by means of an electrode in the vessel containing the molten metal thereby providing a return path for the eddy <span class="hlt">currents</span> induced in the metal <span class="hlt">sheet</span> by the AC coil generated magnetic flux. Variation in the geometry of the conducting shield allows the magnetic flux between the metal <span class="hlt">sheet</span> and the conducting shield to be varied and the thickness in surface quality of the metal <span class="hlt">sheet</span> to be controlled. Side guards provide lateral containment for the molten metal <span class="hlt">sheet</span> and stabilize and shape the magnetic field while a leader <span class="hlt">sheet</span> having electromagnetic characteristics similar to those of the metal <span class="hlt">sheet</span> is used to start the casting process and precedes the molten metal <span class="hlt">sheet</span> through the magnet and forms a continuous <span class="hlt">sheet</span> therewith. The magnet may be either U-shaped with a single racetrack coil or may be rectangular with a pair of facing bedstead coils.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/866574','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/866574"><span>Horizontal electromagnetic casting of thin metal <span class="hlt">sheets</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Hull, John R.; Lari, Robert J.; Praeg, Walter F.; Turner, Larry R.</p> <p>1988-01-01</p> <p>Thin metal <span class="hlt">sheets</span> are cast by magnetically suspending molten metal deposited within a ferromagnetic yoke and between AC conducting coils and linearly displacing the magnetically levitated liquid metal while it is being cooled to form a solid metal <span class="hlt">sheet</span>. Magnetic flux increases as the molten metal <span class="hlt">sheet</span> moves downward and decreases as the molten metal <span class="hlt">sheet</span> moves upward to stabilize the <span class="hlt">sheet</span> and maintain it in equilibrium as it is linearly displaced and solidified by cooling gases. A conducting shield is electrically coupled to the molten metal <span class="hlt">sheet</span> by means of either metal <span class="hlt">sheet</span> engaging rollers or brushes on the solidified metal, and by means of an electrode in the vessel containing the molten metal thereby providing a return path for the eddy <span class="hlt">currents</span> induced in the metal <span class="hlt">sheet</span> by the AC coil generated magnetic flux. Variation in the geometry of the conducting shield allows the magnetic flux between the metal <span class="hlt">sheet</span> and the conducting shield to be varied and the thickness in surface quality of the metal <span class="hlt">sheet</span> to be controlled. Side guards provide lateral containment for the molten metal <span class="hlt">sheet</span> and stabilize and shape the magnetic field while a leader <span class="hlt">sheet</span> having electromagnetic characteristics similar to those of the metal <span class="hlt">sheet</span> is used to start the casting process and precedes the molten metal <span class="hlt">sheet</span> through the magnet and forms a continuous <span class="hlt">sheet</span> therewith. The magnet may be either U-shaped with a single racetrack coil or may be rectangular with a pair of facing bedstead coils.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19930053274&hterms=energy+storage&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Denergy%2Bstorage','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19930053274&hterms=energy+storage&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Denergy%2Bstorage"><span>Energy storage and dissipation in the magnetotail during substorms. I - Particle simulations. II - MHD simulations</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Winglee, R. M.; Steinolfson, R. S.</p> <p>1993-01-01</p> <p>2D electromagnetic particle simulations are used to investigate the dynamics of the <span class="hlt">tail</span> during development of substorms under the influence of the pressure in the magnetospheric boundary layer and the dawn-to-dusk electric field. It is shown that pressure pulses result in thinning of the <span class="hlt">tail</span> <span class="hlt">current</span> <span class="hlt">sheet</span> as the magnetic field becomes pinched near the region where the pressure pulse is applied. The pinching leads to the tailward flow of the <span class="hlt">current</span> <span class="hlt">sheet</span> plasma and the eventual formation and injection of a plasmoid. Surges in the dawn-to-dusk electric field cause plasma on the flanks to convect into the center of the <span class="hlt">current</span> <span class="hlt">sheet</span>, thereby thinning the <span class="hlt">current</span> <span class="hlt">sheet</span>. The pressure in the magnetospheric boundary laser is coupled to the dawn-to-dusk electric field through the conductivity of the <span class="hlt">tail</span>. Changes in the predicted evolution of the magnetosphere during substorms due to changes in the resistivity are investigated under the assumption that MHD theory provides a suitable representation of the global or large-scale evolution of the magnetotail to changes in the solar wind and to reconnection at the dayside magnetopause. It is shown that the overall evolution of the magnetosphere is about the same for three different resistivity distributions with plasmoid formation and ejection in each case.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1177241','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/1177241"><span>Steady State Load Characterization Fact <span class="hlt">Sheet</span>: 2012 Chevy Volt</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Scoffield, Don</p> <p>2015-03-01</p> <p>This fact <span class="hlt">sheet</span> characterizes the steady state charging behavior of a 2012 Chevy Volt. Both level 1 charging (120 volt) and level 2 charging (208 volts) is investigated. This fact <span class="hlt">sheet</span> contains plots of efficiency, power factor, and <span class="hlt">current</span> harmonics as vehicle charging is curtailed. Prominent <span class="hlt">current</span> harmonics are also displayed in a histogram for various charge rates.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28085468','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28085468"><span>Velocity autocorrelation function in supercooled liquids: Long-time <span class="hlt">tails</span> and anomalous shear-wave propagation.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Peng, H L; Schober, H R; Voigtmann, Th</p> <p>2016-12-01</p> <p>Molecular dynamic simulations are performed to reveal the long-time behavior of the velocity autocorrelation function (VAF) by utilizing the finite-size effect in a Lennard-Jones binary mixture. Whereas in normal liquids the classical positive t^{-3/2} long-time <span class="hlt">tail</span> is observed, we find in supercooled liquids a negative <span class="hlt">tail</span>. It is strongly influenced by the transfer of the transverse <span class="hlt">current</span> wave across the period boundary. The t^{-5/2} decay of the negative long-time <span class="hlt">tail</span> is confirmed in the spectrum of VAF. Modeling the long-time transverse <span class="hlt">current</span> within a generalized Maxwell model, we reproduce the negative long-time <span class="hlt">tail</span> of the VAF, but with a slower algebraic t^{-2} decay.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4304130','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4304130"><span>From dinosaurs to birds: a <span class="hlt">tail</span> of evolution</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p></p> <p>2014-01-01</p> <p>A particularly critical event in avian evolution was the transition from long- to short-<span class="hlt">tailed</span> birds. Primitive bird <span class="hlt">tails</span> underwent significant alteration, most notably reduction of the number of caudal vertebrae and fusion of the distal caudal vertebrae into an ossified pygostyle. These changes, among others, occurred over a very short evolutionary interval, which brings into focus the underlying mechanisms behind those changes. Despite the wealth of studies delving into avian evolution, virtually nothing is understood about the genetic and developmental events responsible for the emergence of short, fused <span class="hlt">tails</span>. In this review, we summarize the <span class="hlt">current</span> understanding of the signaling pathways and morphological events that contribute to <span class="hlt">tail</span> extension and termination and examine how mutations affecting the genes that control these pathways might influence the evolution of the avian <span class="hlt">tail</span>. To generate a list of candidate genes that may have been modulated in the transition to short-<span class="hlt">tailed</span> birds, we analyzed a comprehensive set of mouse mutants. Interestingly, a prevalent pleiotropic effect of mutations that cause fused caudal vertebral bodies (as in the pygostyles of birds) is <span class="hlt">tail</span> truncation. We identified 23 mutations in this class, and these were primarily restricted to genes involved in axial extension. At least half of the mutations that cause short, fused <span class="hlt">tails</span> lie in the Notch/Wnt pathway of somite boundary formation or differentiation, leading to changes in somite number or size. Several of the mutations also cause additional bone fusions in the trunk skeleton, reminiscent of those observed in primitive and modern birds. All of our findings were correlated to the fossil record. An open question is whether the relatively sudden appearance of short-<span class="hlt">tailed</span> birds in the fossil record could be accounted for, at least in part, by the pleiotropic effects generated by a relatively small number of mutational events. PMID:25621146</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_15 --> <div id="page_16" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="301"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMSM43A2488M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMSM43A2488M"><span>The Dst Recovery Near Substorm Onset Due to the Transformation of the Blocked Cross-<span class="hlt">Tail</span> <span class="hlt">Current</span> into the Substorm <span class="hlt">Current</span> Wedge</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>McWilliams, K. A.; Sofko, G. J.; Hussey, G. C.; Reimer, A. S.</p> <p>2016-12-01</p> <p>During the growth phase the convex curvature of the lobe field lines permits eastward curvature <span class="hlt">current</span> to dominate on those lobe lines, which blocks the westward cross-<span class="hlt">tail</span> <span class="hlt">current</span> (XTJ). The blocked XTJ (BXTJ) is diverted earthward through the tailward portion of the transition plasmasheet (TPS) region of predominantly dipole lines tailward of the plasmapause. The flow shear of the BXTJ in the TPS produces a downward meridional FAC that results in the pre-onset proton arc in the subauroral region. This ionospheric signature of the growth phase lasts for about an hour, ending about 15 minutes before onset, when the pre-onset electron arc appears. Ions in the outer radiation belt precipitate equatorward of the meridional FAC system, because they are on stretched field lines tailward of the ion trapping boundary. The ion precipitation causes the ionospheric conductivity to increases substantially, providing a new high-conductivity route in the ionosphere for the BXTJ. This diversion of the BXTJ forms the Substorm <span class="hlt">Current</span> Wedge. During the pre-onset proton arc interval, the intensification of the ring <span class="hlt">current</span> and the flow of the BXTJ cause the Dst index to fall. When the BXTJ is diverted into the ionosphere and forms the substorm <span class="hlt">current</span> wedge, it produces a northward magnetic field that causes Dst to have a brief positive deflection of 15-20 nT, despite all indications that the ring <span class="hlt">current</span> continues to grow. The positive Dst deflection is the result both of the loss of the BXTJ from the tailward portion of the TPS and of its new northward field generated by its new route along the SCW. Note that there are two disruptions of the XTJ, first the early growth phase lobe line blocking that diverts the BXTJ earthward into the TPS region, and second (over an hour later, near onset) by the transformation of the BXTJ into the SCW.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19930072240&hterms=balance+sheet&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dbalance%2Bsheet','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19930072240&hterms=balance+sheet&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dbalance%2Bsheet"><span>Characteristics of ion flow in the quiet state of the inner plasma <span class="hlt">sheet</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Angelopoulos, V.; Kennel, C. F.; Coroniti, F. V.; Pellat, R.; Spence, H. E.; Kivelson, M. G.; Walker, R. J.; Baumjohann, W.; Feldman, W. C.; Gosling, J. T.</p> <p>1993-01-01</p> <p>We use AMPTE/IRM and ISEE 2 data to study the properties of the high beta plasma <span class="hlt">sheet</span>, the inner plasma <span class="hlt">sheet</span> (IPS). Bursty bulk flows (BBFs) are excised from the two databases, and the average flow pattern in the non-BBF (quiet) IPS is constructed. At local midnight this ensemble-average flow is predominantly duskward; closer to the flanks it is mostly earthward. The flow pattern agrees qualitatively with calculations based on the Tsyganenko (1987) model (T87), where the earthward flow is due to the ensemble-average cross <span class="hlt">tail</span> electric field and the duskward flow is the diamagnetic drift due to an inward pressure gradient. The IPS is on the average in pressure equilibrium with the lobes. Because of its large variance the average flow does not represent the instantaneous flow field. Case studies also show that the non-BBF flow is highly irregular and inherently unsteady, a reason why earthward convection can avoid a pressure balance inconsistency with the lobes. The ensemble distribution of velocities is a fundamental observable of the quiet plasma <span class="hlt">sheet</span> flow field.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016MMTA...47.4425B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016MMTA...47.4425B"><span>Effect of Temperature and <span class="hlt">Sheet</span> Temper on Isothermal Solidification Kinetics in Clad Aluminum Brazing <span class="hlt">Sheet</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Benoit, Michael J.; Whitney, Mark A.; Wells, Mary A.; Winkler, Sooky</p> <p>2016-09-01</p> <p>Isothermal solidification (IS) is a phenomenon observed in clad aluminum brazing <span class="hlt">sheets</span>, wherein the amount of liquid clad metal is reduced by penetration of the liquid clad into the core. The objective of the <span class="hlt">current</span> investigation is to quantify the rate of IS through the use of a previously derived parameter, the Interface Rate Constant (IRC). The effect of peak temperature and initial <span class="hlt">sheet</span> temper on IS kinetics were investigated. The results demonstrated that IS is due to the diffusion of silicon (Si) from the liquid clad layer into the solid core. Reduced amounts of liquid clad at long liquid duration times, a roughened <span class="hlt">sheet</span> surface, and differences in resolidified clad layer morphology between <span class="hlt">sheet</span> tempers were observed. Increased IS kinetics were predicted at higher temperatures by an IRC model as well as by experimentally determined IRC values; however, the magnitudes of these values are not in good agreement due to deficiencies in the model when applied to alloys. IS kinetics were found to be higher for <span class="hlt">sheets</span> in the fully annealed condition when compared with work-hardened <span class="hlt">sheets</span>, due to the influence of core grain boundaries providing high diffusivity pathways for Si diffusion, resulting in more rapid liquid clad penetration.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018EML....14...37A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018EML....14...37A"><span>High performance electrode material for supercapacitors based on α-Co(OH)2 nano-<span class="hlt">sheets</span> prepared through pulse <span class="hlt">current</span> cathodic electro-deposition (PC-CED)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Aghazadeh, Mustafa; Rashidi, Amir; Ganjali, Mohammad Reza</p> <p>2018-01-01</p> <p>In this paper, the well-defined nano-<span class="hlt">sheets</span> of α-Co(OH)2 were prepared through the cathodic electrosynthesis from an additive-free aqueous cobalt nitrate bath. The pulse <span class="hlt">current</span> cathodic electro-deposition (PC-CED) was used as the means for the controlling the OH- electrogeneration on the cathode surface. The characteristics and electrochemical behavior of the prepared cobalt hydroxide were also assessed through SEM, TEM, XRD, BET, and IR. The results proved the product to be composed of crystalline pure α phase of cobalt hydroxide with <span class="hlt">sheet</span>-like morphology at nanoscale. Evaluations of the electrochemical behaviour of the α-Co(OH)2 nano-<span class="hlt">sheets</span> revealed that they are capable to delivering the specific capacitance of 1122 F g-1 at a discharge load of 3 A g-1 and SC retention of 84% after 4000 continues discharging cycles, suggesting the nano-<span class="hlt">sheets</span> as promising candidates for use in electrochemical supercapacitors. Further, the method used for the preparation of the compounds enjoys the capability of being scaled up. [Figure not available: see fulltext.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19870027662&hterms=earth+magnetic+field&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dearth%2Bmagnetic%2Bfield','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19870027662&hterms=earth+magnetic+field&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dearth%2Bmagnetic%2Bfield"><span>An MHD simulation of the effects of the interplanetary magnetic field By component on the interaction of the solar wind with the earth's magnetosphere during southward interplanetary magnetic field</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Ogino, T.; Walker, R. J.; Ashour-Abdalla, M.; Dawson, J. M.</p> <p>1986-01-01</p> <p>The interaction between the solar wind and the earth's magnetosphere has been studied by using a time-dependent three-dimensional MHD model in which the IMF pointed in several directions between dawnward and southward. When the IMF is dawnward, the dayside cusp and the <span class="hlt">tail</span> lobes shift toward the morningside in the northern magnetosphere. The plasma <span class="hlt">sheet</span> rotates toward the north on the dawnside of the <span class="hlt">tail</span> and toward the south on the duskside. For an increasing southward IMF component, the plasma <span class="hlt">sheet</span> becomes thinner and subsequently wavy because of patchy or localized <span class="hlt">tail</span> reconnection. At the same time, the <span class="hlt">tail</span> field-aligned <span class="hlt">currents</span> have a filamentary layered structure. When projected onto the northern polar cap, the filamentary field-aligned <span class="hlt">currents</span> are located in the same area as the region 1 <span class="hlt">currents</span>, with a pattern similar to that associated with auroral surges. Magnetic reconnection also occurs on the dayside magnetopause for southward IMF.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001JGR...10619117T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001JGR...10619117T"><span>Plasma <span class="hlt">sheet</span> dynamics observed by the Polar spacecraft in association with substorm onsets</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Toivanen, P. K.; Baker, D. N.; Peterson, W. K.; Li, X.; Donovan, E. F.; Viljanen, A.; Keiling, A.; Wygant, J. R.; Kletzing, C. A.</p> <p>2001-09-01</p> <p>We present observations of the Polar spacecraft of magnetospheric substorm signatures in the plasma <span class="hlt">sheet</span> midway along auroral field lines between the ionosphere and the equatorial plasma <span class="hlt">sheet</span>. On October 17, 1997, Polar was located in the onset meridian in conjunction with the Scandinavian magnetometer chain (International Monitor for Auroral Geomagnetic Effects; IMAGE). In addition, a geostationary spacecraft, LANL-97A, was located near the onset meridian. On August 29, 1997, Polar was magnetically conjugate to the Canadian magnetometer chain (Canadian Auroral Network for the OPEN Program Unified Study; CANOPUS) ~5 hours east of the onset meridian. In both cases, substorm activity was manifested as strong magnetic (20 nT) and electric (40 mVm-1) field variations with bursts of parallel Poynting flux (~1 ergcm-2s-1), predominantly directed toward the ionosphere. In the first event Polar was located in the plasma <span class="hlt">sheet</span> near the plasma <span class="hlt">sheet</span> boundary, and the field variations were initiated at the ground onset. In the second event, Polar crossed the plasma <span class="hlt">sheet</span> boundary to the <span class="hlt">tail</span> lobes a few minutes prior to a local plasma <span class="hlt">sheet</span> expansion. As Polar was engulfed by the plasma <span class="hlt">sheet</span>, the field variations occurred in the previously quiet plasma <span class="hlt">sheet</span> boundary. This coincided with the auroral bulge reaching the CANOPUS stations. We compare these two events and argue that the field variations were most probably signatures of the reconnection of open field lines and the subsequent enhanced earthward flows. Furthermore, weak flow bursts were observed at Polar in both events ~9 min before the onset. In the first event, a gradual development toward a negative bay and a burst of Pi2 pulsations were associated with the flow bursts. We anticipate that these signatures, often described in terms of pseudobreakups, were a precursor of the substorm onset, the initiation of the reconnection of closed field lines.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018MNRAS.478..983S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018MNRAS.478..983S"><span>Predicting pulsar scintillation from refractive plasma <span class="hlt">sheets</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Simard, Dana; Pen, Ue-Li</p> <p>2018-07-01</p> <p>The dynamic and secondary spectra of many pulsars show evidence for long-lived, aligned images of the pulsar that are stationary on a thin scattering <span class="hlt">sheet</span>. One explanation for this phenomenon considers the effects of wave crests along <span class="hlt">sheets</span> in the ionized interstellar medium, such as those due to Alfvén waves propagating along <span class="hlt">current</span> <span class="hlt">sheets</span>. If these <span class="hlt">sheets</span> are closely aligned to our line of sight to the pulsar, high bending angles arise at the wave crests and a selection effect causes alignment of images produced at different crests, similar to grazing reflection off of a lake. Using geometric optics, we develop a simple parametrized model of these corrugated <span class="hlt">sheets</span> that can be constrained with a single observation and that makes observable predictions for variations in the scintillation of the pulsar over time and frequency. This model reveals qualitative differences between lensing from overdense and underdense corrugated <span class="hlt">sheets</span>: only if the <span class="hlt">sheet</span> is overdense compared to the surrounding interstellar medium can the lensed images be brighter than the line-of-sight image to the pulsar, and the faint lensed images are closer to the pulsar at higher frequencies if the <span class="hlt">sheet</span> is underdense, but at lower frequencies if the <span class="hlt">sheet</span> is overdense.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018MNRAS.tmp.1079S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018MNRAS.tmp.1079S"><span>Predicting Pulsar Scintillation from Refractive Plasma <span class="hlt">Sheets</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Simard, Dana; Pen, Ue-Li</p> <p>2018-05-01</p> <p>The dynamic and secondary spectra of many pulsars show evidence for long-lived, aligned images of the pulsar that are stationary on a thin scattering <span class="hlt">sheet</span>. One explanation for this phenomenon considers the effects of wave crests along <span class="hlt">sheets</span> in the ionized interstellar medium, such as those due to Alfvén waves propagating along <span class="hlt">current</span> <span class="hlt">sheets</span>. If these <span class="hlt">sheets</span> are closely aligned to our line-of-sight to the pulsar, high bending angles arise at the wave crests and a selection effect causes alignment of images produced at different crests, similar to grazing reflection off of a lake. Using geometric optics, we develop a simple parameterized model of these corrugated <span class="hlt">sheets</span> that can be constrained with a single observation and that makes observable predictions for variations in the scintillation of the pulsar over time and frequency. This model reveals qualitative differences between lensing from overdense and underdense corrugated <span class="hlt">sheets</span>: Only if the <span class="hlt">sheet</span> is overdense compared to the surrounding interstellar medium can the lensed images be brighter than the line-of-sight image to the pulsar, and the faint lensed images are closer to the pulsar at higher frequencies if the <span class="hlt">sheet</span> is underdense, but at lower frequencies if the <span class="hlt">sheet</span> is overdense.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMSM43E..03M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMSM43E..03M"><span>Plasma <span class="hlt">sheet</span> low-entropy flow channels and dipolarization fronts from macro to micro scales: Global MHD and PIC simulations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Merkin, V. G.; Wiltberger, M. J.; Sitnov, M. I.; Lyon, J.</p> <p>2016-12-01</p> <p>Observations show that much of plasma and magnetic flux transport in the magnetotail occurs in the form of discrete activations such as bursty bulk flows (BBFs). These flow structures are typically associated with strong peaks of the Z-component of the magnetic field normal to the magnetotail <span class="hlt">current</span> <span class="hlt">sheet</span> (dipolarization fronts, DFs), as well as density and flux tube entropy depletions also called plasma bubbles. Extensive observational analysis of these structures has been carried out using data from Geotail spacecraft and more recently from Cluster, THEMIS, and MMS multi-probe missions. Global magnetohydrodynamic (MHD) simulations of the magnetosphere reveal similar plasma <span class="hlt">sheet</span> flow bursts, in agreement with regional MHD and particle-in-cell (PIC) models. We present results of high-resolution simulations using the Lyon-Fedder-Mobarry (LFM) global MHD model and analyze the properties of the bursty flows including their structure and evolution as they propagate from the mid-<span class="hlt">tail</span> region into the inner magnetosphere. We highlight similarities and differences with the corresponding observations and discuss comparative properties of plasma bubbles and DFs in our global MHD simulations with their counterparts in 3D PIC simulations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AnGeo..35.1269P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AnGeo..35.1269P"><span><span class="hlt">Tail</span> reconnection in the global magnetospheric context: Vlasiator first results</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Palmroth, Minna; Hoilijoki, Sanni; Juusola, Liisa; Pulkkinen, Tuija I.; Hietala, Heli; Pfau-Kempf, Yann; Ganse, Urs; von Alfthan, Sebastian; Vainio, Rami; Hesse, Michael</p> <p>2017-11-01</p> <p>The key dynamics of the magnetotail have been researched for decades and have been associated with either three-dimensional (3-D) plasma instabilities and/or magnetic reconnection. We apply a global hybrid-Vlasov code, Vlasiator, to simulate reconnection self-consistently in the ion kinetic scales in the noon-midnight meridional plane, including both dayside and nightside reconnection regions within the same simulation box. Our simulation represents a numerical experiment, which turns off the 3-D instabilities but models ion-scale reconnection physically accurately in 2-D. We demonstrate that many known <span class="hlt">tail</span> dynamics are present in the simulation without a full description of 3-D instabilities or without the detailed description of the electrons. While multiple reconnection sites can coexist in the plasma <span class="hlt">sheet</span>, one reconnection point can start a global reconfiguration process, in which magnetic field lines become detached and a plasmoid is released. As the simulation run features temporally steady solar wind input, this global reconfiguration is not associated with sudden changes in the solar wind. Further, we show that lobe density variations originating from dayside reconnection may play an important role in stabilising <span class="hlt">tail</span> reconnection.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AAS...22711807R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AAS...22711807R"><span>A Tale of Two <span class="hlt">Tails</span>: Exploring Stellar Populations in the Tidal <span class="hlt">Tails</span> of NGC 3256</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rodruck, Michael; Charlton, Jane C.; Konstantopoulos, Iraklis</p> <p>2016-01-01</p> <p>Galaxy interactions can inject material into the intergalactic medium via violent gravitational dynamics, often visualized in tidal <span class="hlt">tails</span>. The composition of these <span class="hlt">tails</span> has remained a mystery, as previous studies have focused on detecting tidal features, rather than the composite material itself. We have developed an observing program using deep, multiband imaging to probe the chaotic regions of tidal <span class="hlt">tails</span> in search for an underlying stellar population. NGC 3256's twin tidal <span class="hlt">tails</span> serve as a case study for this new technique. Our results show color values of u - g = 1.15 and r - i = 0.08 for the Western <span class="hlt">tail</span>, and u - g = 1.33 and r - i = 0.22 for the Eastern <span class="hlt">tail</span>, corresponding to discrepant ages between the <span class="hlt">tails</span> of approximately 320 Myr and 785 Myr, respectively. With the interaction age of the system measured at 400 Myr, we find the stellar light in Western <span class="hlt">tail</span> to be dominated by disrupted star clusters formed during and after the interaction, whereas the light from the Eastern <span class="hlt">tail</span> is dominated by a 10 Gyr population originating from the host galaxies. We fit the Eastern <span class="hlt">tail</span> color to a Mixed Stellar Population (MSP) model comprised 94% by mass of a 10 Gyr stellar population, and 6% of a 309 Myr population. We find 52% of the bolometric flux originating from this 10 Gyr population. We also detect a blue to red color gradient in each <span class="hlt">tail</span>, running from galactic center to <span class="hlt">tail</span> tip. In addition to tidal <span class="hlt">tail</span> light, we detect 29 star cluster candidates (SCCs) in the Western <span class="hlt">tail</span> and 19 in the Eastern, with mean ages of 282 Myr and 98 Myr respectively. Interestingly, we find an excess of very blue SCCs in the Eastern <span class="hlt">tail</span> as compared to the Western <span class="hlt">tail</span>, marking a recent, small episode of star formation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19850066650&hterms=high+current+electron+beam&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dhigh%2Bcurrent%2Belectron%2Bbeam','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19850066650&hterms=high+current+electron+beam&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dhigh%2Bcurrent%2Belectron%2Bbeam"><span>Unstable <span class="hlt">current</span> systems and plasma instabilities in astrophysics; Proceedings of the 107th Symposium, University of Maryland, College Park, August 8-11, 1983</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Kundu, M. R. (Editor); Holman, G. D. (Editor)</p> <p>1985-01-01</p> <p>Among the topics discussed are: magnetic field reconnection in cosmic plasmas; energy dissipation mechanisms in the solar corona; and the acceleration of runaway electrons and Joule heating in solar flares. Consideration is also given to: the nonlinear evolution of the resistive tearing mode; anomalous transport in <span class="hlt">current</span> <span class="hlt">sheets</span>; equilibrium and instability in extragalactic jets; and magnetic field reconnection in differentially rotating accretion disks. Among additional topics discussed are: the creation of high energy electron <span class="hlt">tails</span> by lower hybrid waves and its connection with type-II and type-III bursts; beam <span class="hlt">current</span> systems in solar flares; and the spatio-temporal features of microwave emissions of active regions and flares.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20140017077','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20140017077"><span>Forced Reconnection in the Near Magnetotail: Onset and Energy Conversion in PIC and MHD Simulations</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Birn, J.; Hesse, Michael</p> <p>2014-01-01</p> <p>Using two-dimensional particle-in-cell (PIC) together with magnetohydrodynamic (MHD) Q1 simulations of magnetotail dynamics, we investigate the evolution toward onset of reconnection and the subsequent energy transfer and conversion. In either case, reconnection onset is preceded by a driven phase, during which magnetic flux is added to the <span class="hlt">tail</span> at the high-latitude boundaries, followed by a relaxation phase, during which the configuration continues to respond to the driving. The boundary deformation leads to the formation of thin embedded <span class="hlt">current</span> <span class="hlt">sheets</span>, which are bifurcated in the near <span class="hlt">tail</span>, converging to a single <span class="hlt">sheet</span> farther out in the MHD simulations. The thin <span class="hlt">current</span> <span class="hlt">sheets</span> in the PIC simulation are carried by electrons and are associated with a strong perpendicular electrostatic field, which may provide a connection to parallel potentials and auroral arcs and an ionospheric signal even prior to the onset of reconnection. The PIC simulation very well satisfies integral entropy conservation (intrinsic to ideal MHD) during this phase, supporting ideal ballooning stability. Eventually, the <span class="hlt">current</span> intensification leads to the onset of reconnection, the formation and ejection of a plasmoid, and a collapse of the inner <span class="hlt">tail</span>. The earthward flow shows the characteristics of a dipolarization front: enhancement of Bz, associated with a thin vertical electron <span class="hlt">current</span> <span class="hlt">sheet</span> in the PIC simulation. Both MHD and PIC simulations show a dominance of energy conversion from incoming Poynting flux to outgoing enthalpy flux, resulting in heating of the inner <span class="hlt">tail</span>. Localized Joule dissipation plays only a minor role.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22654254-controlling-influence-magnetic-field-solar-wind-outflow-investigation-using-current-sheet-source-surface-model','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22654254-controlling-influence-magnetic-field-solar-wind-outflow-investigation-using-current-sheet-source-surface-model"><span>CONTROLLING INFLUENCE OF MAGNETIC FIELD ON SOLAR WIND OUTFLOW: AN INVESTIGATION USING <span class="hlt">CURRENT</span> <span class="hlt">SHEET</span> SOURCE SURFACE MODEL</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Poduval, B., E-mail: bpoduval@spacescience.org</p> <p>2016-08-10</p> <p>This Letter presents the results of an investigation into the controlling influence of large-scale magnetic field of the Sun in determining the solar wind outflow using two magnetostatic coronal models: <span class="hlt">current</span> <span class="hlt">sheet</span> source surface (CSSS) and potential field source surface. For this, we made use of the Wang and Sheeley inverse correlation between magnetic flux expansion rate (FTE) and observed solar wind speed (SWS) at 1 au. During the period of study, extended over solar cycle 23 and beginning of solar cycle 24, we found that the coefficients of the fitted quadratic equation representing the FTE–SWS inverse relation exhibited significantmore » temporal variation, implying the changing pattern of the influence of FTE on SWS over time. A particularly noteworthy feature is an anomaly in the behavior of the fitted coefficients during the extended minimum, 2008–2010 (CRs 2073–2092), which is considered due to the particularly complex nature of the solar magnetic field during this period. However, this variation was significant only for the CSSS model, though not a systematic dependence on the phase of the solar cycle. Further, we noticed that the CSSS model demonstrated better solar wind prediction during the period of study, which we attribute to the treatment of volume and <span class="hlt">sheet</span> <span class="hlt">currents</span> throughout the corona and the more accurate tracing of footpoint locations resulting from the geometry of the model.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/4794830','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/biblio/4794830"><span><span class="hlt">SHEET</span> PLASMA DEVICE</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Henderson, O.A.</p> <p>1962-07-17</p> <p>An ion-electron plasma heating apparatus of the pinch tube class was developed wherein a plasma is formed by an intense arc discharge through a gas and is radially constricted by the magnetic field of the discharge. To avoid kink and interchange instabilities which can disrupt a conventional arc shortiy after it is formed, the apparatus is a pinch tube with a flat configuration for forming a <span class="hlt">sheet</span> of plasma between two conductive plates disposed parallel and adjacent to the plasma <span class="hlt">sheet</span>. Kink instabilities are suppressed by image <span class="hlt">currents</span> induced in the conductive plates while the interchange instabilities are neutrally stable because of the flat plasma configuration wherein such instabilities may occur but do not dynamically increase in amplitude. (AEC)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSM11C2323L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSM11C2323L"><span>Orientation and spread of reconnection x-line in asymmetric <span class="hlt">current</span> <span class="hlt">sheets</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Liu, Y. H.; Hesse, M.; Wendel, D. E.; Kuznetsova, M.; Wang, S.</p> <p>2017-12-01</p> <p>The magnetic field in solar wind plasmas can shear with Earth's dipole magnetic field at arbitrary angles, and the plasma conditions on the two sides of the (magnetopause) <span class="hlt">current</span> <span class="hlt">sheet</span> can greatly differ. One of the outstanding questions in such asymmetric geometry is what local physics controls the orientation of the reconnection x-line; while the x-line in a simplified 2D model (simulation) always points out of the simulation plane by design, it is unclear how to predict the orientation of the x-line in a fully three-dimensional (3D) system. Using kinetic simulations run on Blue Waters, we develop an approach to explore this 3D nature of the reconnection x-line, and test hypotheses including maximizing the reconnection rate, tearing mode growth rate or reconnection outflow speed, and the bisection solution. Practically, this orientation should correspond to the M-direction of the local LMN coordinate system that is often employed to analyze diffusion region crossings by the Magnetospheric Multiscale Mission (MMS). In this talk, we will also discuss how an x-line spread from a point source in asymmetric geometries, and the boundary effect on the development of the reconnection x-line and turbulence.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19750014179','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19750014179"><span>Observation of low energy protons in the geomagnetic <span class="hlt">tail</span> at lunar distances. M.S. Thesis</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hardy, D. A.</p> <p>1974-01-01</p> <p>Three suprathermal ion detectors stationed on the moon were used to detect a region of plasma flowing antisunward along the ordered field lines of the geomagnetic <span class="hlt">tail</span>, exterior to the plasma <span class="hlt">sheet</span>. The particle flow displays an integral flux, a bulk velocity, temperatures, and number densities uniquely different from the other particle regimes traversed by the moon. No consistent deviation in the field was found to correspond with the occurrence of the events, which have an angular distribution extending between 50 and 100 deg and a spatial distribution over a wide region in both the Y sub sm and Z sub sm directions. The duration of observable particles varies widely between <span class="hlt">tail</span> passages, with an apparent correlation between the number of hours of observation and the Kp index averages over these times. It is proposed that these particles may have entered through the cusp region.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013APS..DFDD28006E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013APS..DFDD28006E"><span>Oblique impact of dense granular <span class="hlt">sheets</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ellowitz, Jake; Guttenberg, Nicholas; Jaeger, Heinrich M.; Nagel, Sidney R.; Zhang, Wendy W.</p> <p>2013-11-01</p> <p>Motivated by experiments showing impacts of granular jets with non-circular cross sections produce thin ejecta <span class="hlt">sheets</span> with anisotropic shapes, we study what happens when two <span class="hlt">sheets</span> containing densely packed, rigid grains traveling at the same speed collide asymmetrically. Discrete particle simulations and a continuum frictional fluid model yield the same steady-state solution of two exit streams emerging from incident streams. When the incident angle Δθ is less than Δθc =120° +/-10° , the exit streams' angles differ from that measured in water <span class="hlt">sheet</span> experiments. Below Δθc , the exit angles from granular and water <span class="hlt">sheet</span> impacts agree. This correspondence is surprising because 2D Euler jet impact, the idealization relevant for both situations, is ill posed: a generic Δθ value permits a continuous family of solutions. Our finding that granular and water <span class="hlt">sheet</span> impacts evolve into the same member of the solution family suggests previous proposals that perturbations such as viscous drag, surface tension or air entrapment select the actual outcome are not correct. <span class="hlt">Currently</span> at Department of Physics, University of Oregon, Eugene, OR 97403.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20010032393&hterms=Russell&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAuthor-Name%26Nf%3DPublication-Date%257CBTWN%2B20000101%2B20001231%26N%3D0%26No%3D20%26Ntt%3DRussell','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20010032393&hterms=Russell&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAuthor-Name%26Nf%3DPublication-Date%257CBTWN%2B20000101%2B20001231%26N%3D0%26No%3D20%26Ntt%3DRussell"><span>Reconnection in Planetary Magnetospheres</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Russell, C. T.</p> <p>2000-01-01</p> <p><span class="hlt">Current</span> <span class="hlt">sheets</span> in planetary magnetospheres that lie between regions of "oppositely-directed" magnetic field are either magnetopause-like, separating plasmas with different properties, or <span class="hlt">tail</span>-like, separating plasmas of rather similar properties. The magnetopause <span class="hlt">current</span> <span class="hlt">sheets</span> generally have a nearly limitless supply of magnetized plasma that can reconnect, possibly setting up steady-state reconnection. In contrast, the plasma on either side of a <span class="hlt">tail</span> <span class="hlt">current</span> <span class="hlt">sheet</span> is stratified so that, as reconnection occurs, the plasma properties, in particular the Alfven velocity, change. If the density drops and the magnetic field increases markedly perpendicular to the <span class="hlt">sheet</span>, explosive reconnection can occur. Even though steady state reconnection can take place at magnetopause <span class="hlt">current</span> <span class="hlt">sheets</span>, the process often appears to be periodic as if a certain low average rate was demanded by the conditions but only a rapid rate was available. Reconnection of sheared fields has been postulated to create magnetic ropes in the solar corona, at the Earth's magnetopause, and in the magnetotail. However, this is not the only way to produce magnetic ropes as the Venus ionosphere shows. The geometry of the reconnecting regions and the plasma conditions both can affect the rate of reconnection. Sorting out the various controlling factors can be assisted through the examination of reconnection in planetary settings. In particular we observe similar small-scale tearing in the magnetopause <span class="hlt">current</span> layers of the Earth, Saturn. Uranus and Neptune and the magnetodisk <span class="hlt">current</span> <span class="hlt">sheet</span> at Jupiter. These sites may be seeds for rapid reconnection if the reconnection site reaches a high Alfven velocity region. In the Jupiter magnetosphere this appears to be achieved with resultant substorm activity. Similar seeds may be present in the Earth's magnetotail with the first one to reach explosive growth dominating the dynamics of the <span class="hlt">tail</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMPP43B1345K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMPP43B1345K"><span>Antarctic Circumpolar <span class="hlt">Current</span> Dynamics and Their Relation to Antarctic Ice <span class="hlt">Sheet</span> and Perennial Sea-Ice Variability in the Central Drake Passage During the Last Climate Cycle</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kuhn, G.; Wu, S.; Hass, H. C.; Klages, J. P.; Zheng, X.; Arz, H. W.; Esper, O.; Hillenbrand, C. D.; Lange, C.; Lamy, F.; Lohmann, G.; Müller, J.; McCave, I. N. N.; Nürnberg, D.; Roberts, J.; Tiedemann, R.; Timmermann, A.; Titschack, J.; Zhang, X.</p> <p>2017-12-01</p> <p>The evolution of the Antarctic Ice <span class="hlt">Sheet</span> during the last climate cycle and the interrelation to global atmospheric and ocean circulation remains controversial and plays an important role for our understanding of ice <span class="hlt">sheet</span> response to modern global warming. The timing and sequence of deglacial warming is relevant for understanding the variability and sensitivity of the Antarctic Ice <span class="hlt">Sheet</span> to climatic changes, and the continuing rise of atmospheric greenhouse gas concentrations. The Antarctic Ice <span class="hlt">Sheet</span> is a pivotal component of the global water budget. Freshwater fluxes from the ice <span class="hlt">sheet</span> may affect the Antarctic Circumpolar <span class="hlt">Current</span> (ACC), which is strongly impacted by the westerly wind belt in the Southern Hemisphere (SHWW) and constricted to its narrowest extent in the Drake Passage. The flow of ACC water masses through Drake Passage is, therefore, crucial for advancing our understanding of the Southern Ocean's role in global meridional overturning circulation and global climate change. In order to address orbital and millennial-scale variability of the Antarctic ice <span class="hlt">sheet</span> and the ACC, we applied a multi-proxy approach on a sediment core from the central Drake Passage including grain size, iceberg-rafted debris, mineral dust, bulk chemical and mineralogical composition, and physical properties. In combination with already published and new sediment records from the Drake Passage and Scotia Sea, as well as high-resolution data from Antarctic ice cores (WDC, EDML), we now have evidence that during glacial times a more northerly extent of the perennial sea-ice zone decreased ACC <span class="hlt">current</span> velocities in the central Drake Passage. During deglaciation the SHWW shifted southwards due to a decreasing temperature gradient between subtropical and polar latitudes caused by sea ice and ice <span class="hlt">sheet</span> decline. This in turn caused Southern Hemisphere warming, a more vigorous ACC, stronger Southern Ocean ventilation, and warm Circumpolar Deep Water (CDW) upwelling on Antarctic shelves</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_16 --> <div id="page_17" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="321"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1305900','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/1305900"><span>3D electrostatic gyrokinetic electron and fully kinetic ion simulation of lower-hybrid drift instability of Harris <span class="hlt">current</span> <span class="hlt">sheet</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Wang, Zhenyu; Lin, Yu; Wang, Xueyi</p> <p></p> <p>The eigenmode stability properties of three-dimensional lower-hybrid-drift-instabilities (LHDI) in a Harris <span class="hlt">current</span> <span class="hlt">sheet</span> with a small but finite guide magnetic field have been systematically studied by employing the gyrokinetic electron and fully kinetic ion (GeFi) particle-in-cell (PIC) simulation model with a realistic ion-to-electron mass ratio m i/m e. In contrast to the fully kinetic PIC simulation scheme, the fast electron cyclotron motion and plasma oscillations are systematically removed in the GeFi model, and hence one can employ the realistic m i/m e. The GeFi simulations are benchmarked against and show excellent agreement with both the fully kinetic PIC simulation and the analytical eigenmode theory. Our studies indicate that, for small wavenumbers, ky, along the <span class="hlt">current</span> direction, the most unstable eigenmodes are peaked at the location wheremore » $$\\vec{k}$$• $$\\vec{B}$$ =0, consistent with previous analytical and simulation studies. Here, $$\\vec{B}$$ is the equilibrium magnetic field and $$\\vec{k}$$ is the wavevector perpendicular to the nonuniformity direction. As ky increases, however, the most unstable eigenmodes are found to be peaked at $$\\vec{k}$$ •$$\\vec{B}$$ ≠0. Additionally, the simulation results indicate that varying m i/m e, the <span class="hlt">current</span> <span class="hlt">sheet</span> width, and the guide magnetic field can affect the stability of LHDI. Simulations with the varying mass ratio confirm the lower hybrid frequency and wave number scalings.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1305900-electrostatic-gyrokinetic-electron-fully-kinetic-ion-simulation-lower-hybrid-drift-instability-harris-current-sheet','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1305900-electrostatic-gyrokinetic-electron-fully-kinetic-ion-simulation-lower-hybrid-drift-instability-harris-current-sheet"><span>3D electrostatic gyrokinetic electron and fully kinetic ion simulation of lower-hybrid drift instability of Harris <span class="hlt">current</span> <span class="hlt">sheet</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Wang, Zhenyu; Lin, Yu; Wang, Xueyi; ...</p> <p>2016-07-07</p> <p>The eigenmode stability properties of three-dimensional lower-hybrid-drift-instabilities (LHDI) in a Harris <span class="hlt">current</span> <span class="hlt">sheet</span> with a small but finite guide magnetic field have been systematically studied by employing the gyrokinetic electron and fully kinetic ion (GeFi) particle-in-cell (PIC) simulation model with a realistic ion-to-electron mass ratio m i/m e. In contrast to the fully kinetic PIC simulation scheme, the fast electron cyclotron motion and plasma oscillations are systematically removed in the GeFi model, and hence one can employ the realistic m i/m e. The GeFi simulations are benchmarked against and show excellent agreement with both the fully kinetic PIC simulation and the analytical eigenmode theory. Our studies indicate that, for small wavenumbers, ky, along the <span class="hlt">current</span> direction, the most unstable eigenmodes are peaked at the location wheremore » $$\\vec{k}$$• $$\\vec{B}$$ =0, consistent with previous analytical and simulation studies. Here, $$\\vec{B}$$ is the equilibrium magnetic field and $$\\vec{k}$$ is the wavevector perpendicular to the nonuniformity direction. As ky increases, however, the most unstable eigenmodes are found to be peaked at $$\\vec{k}$$ •$$\\vec{B}$$ ≠0. Additionally, the simulation results indicate that varying m i/m e, the <span class="hlt">current</span> <span class="hlt">sheet</span> width, and the guide magnetic field can affect the stability of LHDI. Simulations with the varying mass ratio confirm the lower hybrid frequency and wave number scalings.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/6952723-simulation-electrostatic-turbulence-plasma-sheet-boundary-layer-electron-currents-bean-shaped-ion-beams','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/6952723-simulation-electrostatic-turbulence-plasma-sheet-boundary-layer-electron-currents-bean-shaped-ion-beams"><span>Simulation of electrostatic turbulence in the plasma <span class="hlt">sheet</span> boundary layer with electron <span class="hlt">currents</span> and bean-shaped ion beams</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Nishikawa, K.; Frank, L.A.; Huang, C.Y.</p> <p></p> <p>Plasma data from ISEE 1 show the presence of electron <span class="hlt">currents</span> as well as energetic ion beams in the plasma <span class="hlt">sheet</span> boundary layer. Broadband electrostatic noise and low-frequency electromagnetic bursts are detected in the plasma <span class="hlt">sheet</span> boundary layer, especially in the presence of strong ion flows, <span class="hlt">currents</span>, and steep spacial gradients in the fluxes of few-keV electrons and ions. Particle simulations have been performed to investigate electrostatic turbulence driven by a cold electron beam and/or ion beams with a bean-shaped velocity distribution. The simulation results show that the counterstreaming ion beams as well as the counterstreaming of the cold electronmore » beam and the ion beam excite ion acoustic waves with the Doppler-shifted real frequency ..omega..approx. = +- k/sub parallel/(c/sub s/-V/sub i//sub //sub parallel/). However, the effect of the bean-shaped ion velocity distributions reduces the growth rates of ion acoustic instability. The simulation results also show that the slowing down of the ion beam is larger at the larger perpendicular velocity. The wave spectra of the electric fields at some points for simulations show turbulence generated by growing waves. The frequency of these spectra ranges from ..cap omega../sub i/ to ..omega../sub p//sub e/, which is in qualitative agreement with the satellite data. copyright American Geophysical Union 1988« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017ApJ...836..108K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017ApJ...836..108K"><span>High-latitude Conic <span class="hlt">Current</span> <span class="hlt">Sheets</span> in the Solar Wind</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Khabarova, Olga V.; Malova, Helmi V.; Kislov, Roman A.; Zelenyi, Lev M.; Obridko, Vladimir N.; Kharshiladze, Alexander F.; Tokumaru, Munetoshi; Sokół, Justyna M.; Grzedzielski, Stan; Fujiki, Ken'ichi</p> <p>2017-02-01</p> <p>We provide observational evidence for the existence of large-scale cylindrical (or conic-like) <span class="hlt">current</span> <span class="hlt">sheets</span> (CCSs) at high heliolatitudes. Long-lived CCSs were detected by Ulysses during its passages over the South Solar Pole in 1994 and 2007. The characteristic scale of these tornado-like structures is several times less than a typical width of coronal holes within which the CCSs are observed. CCS crossings are characterized by a dramatic decrease in the solar wind speed and plasma beta typical for predicted profiles of CCSs. Ulysses crossed the same CCS at different heliolatitudes at 2-3 au several times in 1994, as the CCS was declined from the rotation axis and corotated with the Sun. In 2007, a CCS was detected directly over the South Pole, and its structure was strongly highlighted by the interaction with comet McNaught. Restorations of solar coronal magnetic field lines reveal the occurrence of conic-like magnetic separators over the solar poles in both 1994 and 2007. Such separators exist only during solar minima. Interplanetary scintillation data analysis confirms the presence of long-lived low-speed regions surrounded by the typical polar high-speed solar wind in solar minima. Energetic particle flux enhancements up to several MeV/nuc are observed at edges of the CCSs. We built simple MHD models of a CCS to illustrate its key features. The CCSs may be formed as a result of nonaxiality of the solar rotation axis and magnetic axis, as predicted by the Fisk-Parker hybrid heliospheric magnetic field model in the modification of Burger and coworkers.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19950005947','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19950005947"><span>Measurements of atmospheric turbulence effects on <span class="hlt">tail</span> rotor acoustics</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hagen, Martin J.; Yamauchi, Gloria K.; Signor, David B.; Mosher, Marianne</p> <p>1994-01-01</p> <p>Results from an outdoor hover test of a full-scale Lynx <span class="hlt">tail</span> rotor are presented. The investigation was designed to further the understanding of the acoustics of an isolated <span class="hlt">tail</span> rotor hovering out-of-ground effect in atmospheric turbulence, without the effects of the main rotor wake or other helicopter components. Measurements include simultaneous rotor performance, noise, inflow, and far-field atmospheric turbulence. Results with grid-generated inflow turbulence are also presented. The effects of atmospheric turbulence ingestion on rotor noise are quantified. In contradiction to <span class="hlt">current</span> theories, increasing rotor inflow and rotor thrust were found to increase turbulence ingestion noise. This is the final report of Task 13A--Helicopter <span class="hlt">Tail</span> Rotor Noise, of the NASA/United Kingdom Defense Research Agency cooperative Aeronautics Research Program.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1402592','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/1402592"><span>O + ion conic and plasma <span class="hlt">sheet</span> dynamics observed by Van Allen Probe satellites during the 1 June 2013 magnetic storm: Energetic Inner Magnetosphere O + Ions</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Burke, W. J.; Erickson, P. J.; Yang, J.</p> <p></p> <p>The Van Allen Probe satellites were near apogee in the late evening local time sector during the 1 June 2013 magnetic storm's main phase. About an hour after crossing the ring <span class="hlt">current</span>'s “nose structure” into the plasma <span class="hlt">sheet</span>, the satellites encountered a quasiperiodic sequence of 0.08–3 keV O + ions. Pitch angle distributions of this population consistently peaked nearly antiparallel to the local magnetic field. We then interpret this population as O + conics originating in the northern ionosphere. The sequences began as fairly steady state conic fluxes with energies in the ~ 80 to 100 eV range. Over aboutmore » a half hour buildup phase, O + energies peaked near 1 keV. During subsequent release phases lasting ~ 20 min, O + energies returned to low-energy starting points. We argue these observations reflect repeated formations and dissolutions of downward, magnetically aligned electric fields (ε||) layers trapping O + conics between mirror points within heating layers below and electrostatic barriers above. Nearly identical variations were observed at the locations of both satellites during 9 of these 13 conic cycles. Phase differences between cycles were observed at both spacecraft during the remaining events. Most “buildup” to “release” phase transitions coincided with AL index minima. But, in situ magnetometer measurements indicate only weak dipolarizations of <span class="hlt">tail</span>-like magnetic fields. The lack of field-aligned reflected O + and <span class="hlt">tail</span>-like magnetic fields suggest that both ionospheres may be active. However, Southern Hemisphere origin conics cannot be observed since they would be isotropized and accelerated during neutral <span class="hlt">sheet</span> crossings.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1402592-ion-conic-plasma-sheet-dynamics-observed-van-allen-probe-satellites-during-june-magnetic-storm-energetic-inner-magnetosphere-ions','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1402592-ion-conic-plasma-sheet-dynamics-observed-van-allen-probe-satellites-during-june-magnetic-storm-energetic-inner-magnetosphere-ions"><span>O + ion conic and plasma <span class="hlt">sheet</span> dynamics observed by Van Allen Probe satellites during the 1 June 2013 magnetic storm: Energetic Inner Magnetosphere O + Ions</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Burke, W. J.; Erickson, P. J.; Yang, J.; ...</p> <p>2016-05-07</p> <p>The Van Allen Probe satellites were near apogee in the late evening local time sector during the 1 June 2013 magnetic storm's main phase. About an hour after crossing the ring <span class="hlt">current</span>'s “nose structure” into the plasma <span class="hlt">sheet</span>, the satellites encountered a quasiperiodic sequence of 0.08–3 keV O + ions. Pitch angle distributions of this population consistently peaked nearly antiparallel to the local magnetic field. We then interpret this population as O + conics originating in the northern ionosphere. The sequences began as fairly steady state conic fluxes with energies in the ~ 80 to 100 eV range. Over aboutmore » a half hour buildup phase, O + energies peaked near 1 keV. During subsequent release phases lasting ~ 20 min, O + energies returned to low-energy starting points. We argue these observations reflect repeated formations and dissolutions of downward, magnetically aligned electric fields (ε||) layers trapping O + conics between mirror points within heating layers below and electrostatic barriers above. Nearly identical variations were observed at the locations of both satellites during 9 of these 13 conic cycles. Phase differences between cycles were observed at both spacecraft during the remaining events. Most “buildup” to “release” phase transitions coincided with AL index minima. But, in situ magnetometer measurements indicate only weak dipolarizations of <span class="hlt">tail</span>-like magnetic fields. The lack of field-aligned reflected O + and <span class="hlt">tail</span>-like magnetic fields suggest that both ionospheres may be active. However, Southern Hemisphere origin conics cannot be observed since they would be isotropized and accelerated during neutral <span class="hlt">sheet</span> crossings.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JMEP...25.4996P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JMEP...25.4996P"><span>Ni-Flash-Coated Galvannealed Steel <span class="hlt">Sheet</span> with Improved Properties</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pradhan, D.; Dutta, M.; Venugopalan, T.</p> <p>2016-11-01</p> <p>In the last several years, automobile industries have increasingly focused on galvannealed (GA) steel <span class="hlt">sheet</span> due to their superior properties such as weldability, paintability and corrosion protection. To improve the properties further, different coatings on GA have been reported. In this context, an electroplating process (flash coating) of bright and adherent Ni plating was developed on GA steel <span class="hlt">sheet</span> for covering the GA defects and enhancing the performances such as weldability, frictional behavior, corrosion resistance and phosphatability. For better illustration, a comparative study with bare GA steel <span class="hlt">sheet</span> has also been carried out. The maximum electroplating <span class="hlt">current</span> density of 700 A/m2 yielded higher cathode <span class="hlt">current</span> efficiency of 95-98%. The performances showed that Ni-coated (coating time 5-7 s) GA steel <span class="hlt">sheet</span> has better spot weldability, lower dynamic coefficient of friction (0.07 in lubrication) and three times more corrosion resistance compared to bare GA steel <span class="hlt">sheet</span>. Plate-like crystal of phosphate coating with size of 10-25 µm was obtained on the Ni-coated GA. The main phase in the phosphate compound was identified as hopeite (63.4 wt.%) along with other phases such as spencerite (28.3 wt.%) and phosphophyllite (8.3 wt.%).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19930084616','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19930084616"><span>Wind-tunnel Investigation of End-plate Effects of Horizontal <span class="hlt">Tails</span> on a Vertical <span class="hlt">Tail</span> Compared with Available Theory</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Murray, Harry E</p> <p>1946-01-01</p> <p>A vertical-<span class="hlt">tail</span> model with stub fuselage was tested in combination with various simulated horizontal <span class="hlt">tails</span> to determine the effect of horizontal-<span class="hlt">tail</span> span and location on the aerodynamic characteristics of the vertical <span class="hlt">tail</span>. Available theoretical data on end-plate effects were collected and presented in the form most suitable for design purposes. Reasonable agreement was obtained between the measured and theoretical end-plate effects of horizontal <span class="hlt">tails</span> on vertical <span class="hlt">tails</span>, and the data indicated that the end-plate effect was determined more by the location of the horizontal <span class="hlt">tail</span> than by the span of the horizontal <span class="hlt">tail</span>. The horizontal <span class="hlt">tail</span> gave most end-plate effect when located near either tip of the vertical <span class="hlt">tail</span> and, when located near the base of the vertical <span class="hlt">tail</span>, the end-plate effect was increased by moving the horizontal <span class="hlt">tail</span> rearward.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JMMM..398..148A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JMMM..398..148A"><span>Magneto-hydrodynamics of coupled fluid-<span class="hlt">sheet</span> interface with mass suction and blowing</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ahmad, R.</p> <p>2016-01-01</p> <p>There are large number of studies which prescribe the kinematics of the <span class="hlt">sheet</span> and ignore the <span class="hlt">sheet</span>'s mechanics. However, the <span class="hlt">current</span> boundary layer analysis investigates the mechanics of both the electrically conducting fluid and a permeable <span class="hlt">sheet</span>, which makes it distinct from the other studies in the literature. One of the objectives of the <span class="hlt">current</span> study is to (i) examine the behaviour of magnetic field effect for both the surface and the electrically conducting fluid (ii) investigate the heat and mass transfer between a permeable <span class="hlt">sheet</span> and the surrounding electrically conducting fluid across the hydro, thermal and mass boundary layers. Self-similar solutions are obtained by considering the RK45 technique. Analytical solution is also found for the stretching <span class="hlt">sheet</span> case. The skin friction dual solutions are presented for various types of <span class="hlt">sheet</span>. The influence of pertinent parameters on the dimensionless velocity, shear stress, temperature, mass concentration, heat and mass transfer rates on the fluid-<span class="hlt">sheet</span> interface is presented graphically as well as numerically. The obtained results are of potential benefit for studying the electrically conducting flow over various soft surfaces such as synthetic plastics, soft silicone <span class="hlt">sheet</span> and soft synthetic rubber <span class="hlt">sheet</span>. These surfaces are easily deformed by thermal fluctuations or thermal stresses.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22663803-high-latitude-conic-current-sheets-solar-wind','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22663803-high-latitude-conic-current-sheets-solar-wind"><span>High-latitude Conic <span class="hlt">Current</span> <span class="hlt">Sheets</span> in the Solar Wind</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Khabarova, Olga V.; Obridko, Vladimir N.; Kharshiladze, Alexander F.</p> <p></p> <p>We provide observational evidence for the existence of large-scale cylindrical (or conic-like) <span class="hlt">current</span> <span class="hlt">sheets</span> (CCSs) at high heliolatitudes. Long-lived CCSs were detected by Ulysses during its passages over the South Solar Pole in 1994 and 2007. The characteristic scale of these tornado-like structures is several times less than a typical width of coronal holes within which the CCSs are observed. CCS crossings are characterized by a dramatic decrease in the solar wind speed and plasma beta typical for predicted profiles of CCSs. Ulysses crossed the same CCS at different heliolatitudes at 2–3 au several times in 1994, as the CCSmore » was declined from the rotation axis and corotated with the Sun. In 2007, a CCS was detected directly over the South Pole, and its structure was strongly highlighted by the interaction with comet McNaught. Restorations of solar coronal magnetic field lines reveal the occurrence of conic-like magnetic separators over the solar poles in both 1994 and 2007. Such separators exist only during solar minima. Interplanetary scintillation data analysis confirms the presence of long-lived low-speed regions surrounded by the typical polar high-speed solar wind in solar minima. Energetic particle flux enhancements up to several MeV/ nuc are observed at edges of the CCSs. We built simple MHD models of a CCS to illustrate its key features. The CCSs may be formed as a result of nonaxiality of the solar rotation axis and magnetic axis, as predicted by the Fisk–Parker hybrid heliospheric magnetic field model in the modification of Burger and coworkers.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3353516','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3353516"><span>The <span class="hlt">Tail</span> Suspension Test</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Terrillion, Chantelle E.; Piantadosi, Sean C.; Bhat, Shambhu; Gould, Todd D.</p> <p>2012-01-01</p> <p>The <span class="hlt">tail</span>-suspension test is a mouse behavioral test useful in the screening of potential antidepressant drugs, and assessing of other manipulations that are expected to affect depression related behaviors. Mice are suspended by their <span class="hlt">tails</span> with tape, in such a position that it cannot escape or hold on to nearby surfaces. During this test, typically six minutes in duration, the resulting escape oriented behaviors are quantified. The <span class="hlt">tail</span>-suspension test is a valuable tool in drug discovery for high-throughput screening of prospective antidepressant compounds. Here, we describe the details required for implementation of this test with additional emphasis on potential problems that may occur and how to avoid them. We also offer a solution to the <span class="hlt">tail</span> climbing behavior, a common problem that renders this test useless in some mouse strains, such as the widely used C57BL/6. Specifically, we prevent <span class="hlt">tail</span> climbing behaviors by passing mouse <span class="hlt">tails</span> through a small plastic cylinder prior to suspension. Finally, we detail how to manually score the behaviors that are manifested in this test. PMID:22315011</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19840004981','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19840004981"><span>The structure of the plasma <span class="hlt">sheet</span>-lobe boundary in the Earth's magnetotail</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Orsini, S.; Candidi, M.; Formisano, V.; Balsiger, H.; Ghielmetti, A.; Ogilvie, K. W.</p> <p>1982-01-01</p> <p>The structure of the magnetotail plasma <span class="hlt">sheet</span>-plasma lobe boundary was studied by observing the properties of tailward flowing O+ ion beams, detected by the ISEE 2 plasma experiment inside the boundary during three time periods. The computed value of the north-south electric field component as well as the O+ parameters are shown to change at the boundary. The results are related to other observations made in this region. The O+ parameters and the Ez component behavior are shown to be consistent with that expected from the topology of the electric field lines in the <span class="hlt">tail</span> as mapped from the ionosphere.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JGRA..122.2889W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JGRA..122.2889W"><span>High-latitude Pi2 pulsations associated with kink-like neutral <span class="hlt">sheet</span> oscillations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, G. Q.; Volwerk, M.; Zhang, T. L.; Schmid, D.; Yoshikawa, A.</p> <p>2017-03-01</p> <p>A kink-like neutral <span class="hlt">sheet</span> oscillation event observed by Cluster between 1436 and 1445 UT on 15 October 2004 has been investigated. The oscillations with periods between 40 and 60 s, observed at (-13.1, 8.7, -0.5) RE, are dominant in BX and BY. And they propagate mainly duskward with a velocity of (86, 147, 46) km/s. Their periods and velocity can be explained by the magnetic double-gradient instability. These oscillations are accompanied by strong field-aligned <span class="hlt">currents</span> (FACs), which prefer to occur near the strongly tilted <span class="hlt">current</span> <span class="hlt">sheet</span>, and local maximum FAC tends to occur near the neutral <span class="hlt">sheet</span>. The FACs show one-to-one correlated with a high-latitude Pi2 pulsation event recorded by KTN and TIK stations with a delay time of 60 and 90 s, respectively. Both the Pi2 and oscillations propagate westward with a comparative conjunctive speed. These findings suggest a strong relation between the FACs and Pi2, and we infer that the Pi2 is caused by the FACs. The periods of the FACs are modulated by the oscillations but not exactly equal, which is one possible reason that the period of the Pi2 caused by the FACs could be different from the oscillations. We speculate that a <span class="hlt">current</span> circuit between the plasma <span class="hlt">sheet</span> and ionosphere can be formed during strongly tilted <span class="hlt">current</span> <span class="hlt">sheet</span>, and successive tilted <span class="hlt">current</span> <span class="hlt">sheet</span> could generate quasiperiodic multiple FAC systems, which can generate high-latitude Pi2 pulsations and control their periods.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018JPlPh..84a9003V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018JPlPh..84a9003V"><span>Nonlinear energy transfer and <span class="hlt">current</span> <span class="hlt">sheet</span> development in localized Alfvén wavepacket collisions in the strong turbulence limit</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Verniero, J. L.; Howes, G. G.; Klein, K. G.</p> <p>2018-02-01</p> <p>In space and astrophysical plasmas, turbulence is responsible for transferring energy from large scales driven by violent events or instabilities, to smaller scales where turbulent energy is ultimately converted into plasma heat by dissipative mechanisms. The nonlinear interaction between counterpropagating Alfvén waves, denoted Alfvén wave collisions, drives this turbulent energy cascade, as recognized by early work with incompressible magnetohydrodynamic (MHD) equations. Recent work employing analytical calculations and nonlinear gyrokinetic simulations of Alfvén wave collisions in an idealized periodic initial state have demonstrated the key properties that strong Alfvén wave collisions mediate effectively the transfer of energy to smaller perpendicular scales and self-consistently generate <span class="hlt">current</span> <span class="hlt">sheets</span>. For the more realistic case of the collision between two initially separated Alfvén wavepackets, we use a nonlinear gyrokinetic simulation to show here that these key properties persist: strong Alfvén wavepacket collisions indeed facilitate the perpendicular cascade of energy and give rise to <span class="hlt">current</span> <span class="hlt">sheets</span>. Furthermore, the evolution shows that nonlinear interactions occur only while the wavepackets overlap, followed by a clean separation of the wavepackets with straight uniform magnetic fields and the cessation of nonlinear evolution in between collisions, even in the gyrokinetic simulation presented here which resolves dispersive and kinetic effects beyond the reach of the MHD theory.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29239649','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29239649"><span>Goal-directed <span class="hlt">tail</span> use in Colombian spider monkeys (Ateles fusciceps rufiventris) is highly lateralized.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Nelson, Eliza L; Kendall, Giulianna A</p> <p>2018-02-01</p> <p>Behavioral laterality refers to a bias in the use of one side of the body over the other and is commonly studied in paired organs (e.g., hands, feet, eyes, antennae). Less common are reports of laterality in unpaired organs (e.g., trunk, tongue, <span class="hlt">tail</span>). The goal of the <span class="hlt">current</span> study was to examine <span class="hlt">tail</span> use biases across different tasks in the Colombian spider monkey ( Ateles fusciceps rufiventris ) for the first time (N = 14). We hypothesized that task context and task complexity influence <span class="hlt">tail</span> laterality in spider monkeys, and we predicted that monkeys would exhibit strong preferences for using the <span class="hlt">tail</span> for manipulation to solve out-of-reach feeding problems, but not for using the <span class="hlt">tail</span> at rest. Our results show that a subset of spider monkeys solved each of the experimental problems through goal-directed <span class="hlt">tail</span> use (N = 7). However, some tasks were more difficult than others, given the number of monkeys who solved the tasks. Our results supported our predictions regarding laterality in <span class="hlt">tail</span> use and only partially replicated prior work on <span class="hlt">tail</span> use preferences in Geoffroy's spider monkeys ( Ateles geoffroyi ). Overall, skilled <span class="hlt">tail</span> use, but not resting <span class="hlt">tail</span> use, was highly lateralized in Colombian spider monkeys. (PsycINFO Database Record (c) 2018 APA, all rights reserved).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.epa.gov/remedytech/nanotechnology-site-remediation-fact-sheet','PESTICIDES'); return false;" href="https://www.epa.gov/remedytech/nanotechnology-site-remediation-fact-sheet"><span>Nanotechnology for Site Remediation: Fact <span class="hlt">Sheet</span></span></a></p> <p><a target="_blank" href="http://www.epa.gov/pesticides/search.htm">EPA Pesticide Factsheets</a></p> <p></p> <p></p> <p>This fact <span class="hlt">sheet</span> presents a snapshot of nanotechnology and its <span class="hlt">current</span> uses in remediation. It presents information to help site project managers understand the potential applications of this group of technologies at their sites.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014cosp...40E2478P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014cosp...40E2478P"><span>The concept of Magnetically Driven Magnetosphere: storm/substorm dynamics and organization of the magnetotail</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pavlov, Nikolai</p> <p></p> <p>A set of novel ideas and approaches have been found in the long-lasting attempts to better understand how the magnetosphere operates. It is proposed a certain vision of the substorm/storm scenario, of the <span class="hlt">tail</span> structure with moderate magnetic By-component, and with intrinsic turbulence. Particle acceleration and the place of the <span class="hlt">tail</span>'s <span class="hlt">current</span> <span class="hlt">sheet(s</span>) in the proposed vision are discussed as well. For the reasoning of the proposal, several key ideas on the purely magnetospheric topics are included in the presentation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.C23D..01R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.C23D..01R"><span>Ice <span class="hlt">sheet</span> systems and sea level change.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rignot, E. J.</p> <p>2015-12-01</p> <p>Modern views of ice <span class="hlt">sheets</span> provided by satellites, airborne surveys, in situ data and paleoclimate records while transformative of glaciology have not fundamentally changed concerns about ice <span class="hlt">sheet</span> stability and collapse that emerged in the 1970's. Motivated by the desire to learn more about ice <span class="hlt">sheets</span> using new technologies, we stumbled on an unexplored field of science and witnessed surprising changes before realizing that most were coming too fast, soon and large. Ice <span class="hlt">sheets</span> are integrant part of the Earth system; they interact vigorously with the atmosphere and the oceans, yet most of this interaction is not part of <span class="hlt">current</span> global climate models. Since we have never witnessed the collapse of a marine ice <span class="hlt">sheet</span>, observations and exploration remain critical sentinels. At present, these observations suggest that Antarctica and Greenland have been launched into a path of multi-meter sea level rise caused by rapid climate warming. While the <span class="hlt">current</span> loss of ice <span class="hlt">sheet</span> mass to the ocean remains a trickle, every mm of sea level change will take centuries of climate reversal to get back, several major marine-terminating sectors have been pushed out of equilibrium, and ice shelves are irremediably being lost. As glaciers retreat from their salty, warm, oceanic margins, they will melt away and retreat slower, but concerns remain about sea level change from vastly marine-based sectors: 2-m sea level equivalent in Greenland and 23-m in Antarctica. Significant changes affect 2/4 marine-based sectors in Greenland - Jakobshavn Isb. and the northeast stream - with Petermann Gl. not far behind. Major changes have affected the Amundsen Sea sector of West Antarctica since the 1980s. Smaller yet significant changes affect the marine-based Wilkes Land sector of East Antarctica, a reminder that not all marine-based ice is in West Antarctica. Major advances in reducing uncertainties in sea level projections will require massive, interdisciplinary efforts that are not <span class="hlt">currently</span> in place</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22133884-tidal-tails-minor-mergers-ii-comparing-star-formation-tidal-tails-ngc','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22133884-tidal-tails-minor-mergers-ii-comparing-star-formation-tidal-tails-ngc"><span>TIDAL <span class="hlt">TAILS</span> OF MINOR MERGERS. II. COMPARING STAR FORMATION IN THE TIDAL <span class="hlt">TAILS</span> OF NGC 2782</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Knierman, Karen A.; Scowen, Paul; Veach, Todd</p> <p>2013-09-10</p> <p>The peculiar spiral NGC 2782 is the result of a minor merger with a mass ratio {approx}4: 1 occurring {approx}200 Myr ago. This merger produced a molecular and H I-rich, optically bright eastern <span class="hlt">tail</span> and an H I-rich, optically faint western <span class="hlt">tail</span>. Non-detection of CO in the western <span class="hlt">tail</span> by Braine et al. suggested that star formation had not yet begun. However, deep UBVR and H{alpha} narrowband images show evidence of recent star formation in the western <span class="hlt">tail</span>, though it lacks massive star clusters and cluster complexes. Using Herschel PACS spectroscopy, we discover 158 {mu}m [C II] emission at themore » location of the three most luminous H{alpha} sources in the eastern <span class="hlt">tail</span>, but not at the location of the even brighter H{alpha} source in the western <span class="hlt">tail</span>. The western <span class="hlt">tail</span> is found to have a normal star formation efficiency (SFE), but the eastern <span class="hlt">tail</span> has a low SFE. The lack of CO and [C II] emission suggests that the western <span class="hlt">tail</span> H II region may have a low carbon abundance and be undergoing its first star formation. The western <span class="hlt">tail</span> is more efficient at forming stars, but lacks massive clusters. We propose that the low SFE in the eastern <span class="hlt">tail</span> may be due to its formation as a splash region where gas heating is important even though it has sufficient molecular and neutral gas to make massive star clusters. The western <span class="hlt">tail</span>, which has lower gas surface density and does not form high-mass star clusters, is a tidally formed region where gravitational compression likely enhances star formation.« less</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_17 --> <div id="page_18" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="341"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22270578-narrow-ray-tail-double-tails-eso-a3627','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22270578-narrow-ray-tail-double-tails-eso-a3627"><span>THE NARROW X-RAY <span class="hlt">TAIL</span> AND DOUBLE Hα <span class="hlt">TAILS</span> OF ESO 137-002 IN A3627</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Zhang, B.; Lin, X. B.; Kong, X.</p> <p>2013-11-10</p> <p>We present the analysis of a deep Chandra observation of a ∼2 L{sub *} late-type galaxy, ESO 137-002, in the closest rich cluster A3627. The Chandra data reveal a long (∼>40 kpc) and narrow <span class="hlt">tail</span> with a nearly constant width (∼3 kpc) to the southeast of the galaxy, and a leading edge ∼1.5 kpc from the galaxy center on the upstream side of the <span class="hlt">tail</span>. The <span class="hlt">tail</span> is most likely caused by the nearly edge-on stripping of ESO 137-002's interstellar medium (ISM) by ram pressure, compared to the nearly face-on stripping of ESO 137-001 discussed in our previous work. Spectralmore » analysis of individual regions along the <span class="hlt">tail</span> shows that the gas throughout it has a rather constant temperature, ∼1 keV, very close to the temperature of the <span class="hlt">tails</span> of ESO 137-001, if the same atomic database is used. The derived gas abundance is low (∼0.2 solar with the single-kT model), an indication of the multiphase nature of the gas in the <span class="hlt">tail</span>. The mass of the X-ray <span class="hlt">tail</span> is only a small fraction (<5%) of the initial ISM mass of the galaxy, suggesting that the stripping is most likely at an early stage. However, with any of the single-kT, double-kT, and multi-kT models we tried, the <span class="hlt">tail</span> is always 'over-pressured' relative to the surrounding intracluster medium (ICM), which could be due to the uncertainties in the abundance, thermal versus non-thermal X-ray emission, or magnetic support in the ICM. The Hα data from the Southern Observatory for Astrophysical Research show a ∼21 kpc <span class="hlt">tail</span> spatially coincident with the X-ray <span class="hlt">tail</span>, as well as a secondary <span class="hlt">tail</span> (∼12 kpc long) to the east of the main <span class="hlt">tail</span> diverging at an angle of ∼23° and starting at a distance of ∼7.5 kpc from the nucleus. At the position of the secondary Hα <span class="hlt">tail</span>, the X-ray emission is also enhanced at the ∼2σ level. We compare the <span class="hlt">tails</span> of ESO 137-001 and ESO 137-002, and also compare the <span class="hlt">tails</span> to simulations. Both the similarities and differences of the <span class="hlt">tails</span> pose challenges to the simulations. Several</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5884497','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5884497"><span>Automatic early warning of <span class="hlt">tail</span> biting in pigs: 3D cameras can detect lowered <span class="hlt">tail</span> posture before an outbreak</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Jack, Mhairi; Futro, Agnieszka; Talbot, Darren; Zhu, Qiming; Barclay, David; Baxter, Emma M.</p> <p>2018-01-01</p> <p><span class="hlt">Tail</span> biting is a major welfare and economic problem for indoor pig producers worldwide. Low <span class="hlt">tail</span> posture is an early warning sign which could reduce <span class="hlt">tail</span> biting unpredictability. Taking a precision livestock farming approach, we used Time-of-flight 3D cameras, processing data with machine vision algorithms, to automate the measurement of pig <span class="hlt">tail</span> posture. Validation of the 3D algorithm found an accuracy of 73.9% at detecting low vs. not low <span class="hlt">tails</span> (Sensitivity 88.4%, Specificity 66.8%). Twenty-three groups of 29 pigs per group were reared with intact (not docked) <span class="hlt">tails</span> under typical commercial conditions over 8 batches. 15 groups had <span class="hlt">tail</span> biting outbreaks, following which enrichment was added to pens and biters and/or victims were removed and treated. 3D data from outbreak groups showed the proportion of low <span class="hlt">tail</span> detections increased pre-outbreak and declined post-outbreak. Pre-outbreak, the increase in low <span class="hlt">tails</span> occurred at an increasing rate over time, and the proportion of low <span class="hlt">tails</span> was higher one week pre-outbreak (-1) than 2 weeks pre-outbreak (-2). Within each batch, an outbreak and a non-outbreak control group were identified. Outbreak groups had more 3D low <span class="hlt">tail</span> detections in weeks -1, +1 and +2 than their matched controls. Comparing 3D <span class="hlt">tail</span> posture and <span class="hlt">tail</span> injury scoring data, a greater proportion of low <span class="hlt">tails</span> was associated with more injured pigs. Low <span class="hlt">tails</span> might indicate more than just <span class="hlt">tail</span> biting as <span class="hlt">tail</span> posture varied between groups and over time and the proportion of low <span class="hlt">tails</span> increased when pigs were moved to a new pen. Our findings demonstrate the potential for a 3D machine vision system to automate <span class="hlt">tail</span> posture detection and provide early warning of <span class="hlt">tail</span> biting on farm. PMID:29617403</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19820028337&hterms=1103&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3D%2526%25231103','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19820028337&hterms=1103&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3D%2526%25231103"><span>Seasonal dependence of large-scale Birkeland <span class="hlt">currents</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Fujii, R.; Iijima, T.; Potemra, T. A.; Sugiura, M.</p> <p>1981-01-01</p> <p>Seasonal variations of large-scale Birkeland <span class="hlt">currents</span> are examined in a study of the source mechanisms and the closure of the three-dimensional <span class="hlt">current</span> systems in the ionosphere. Vector magnetic field data acquired by the TRIAD satellite in the Northern Hemisphere were analyzed for the statistics of single <span class="hlt">sheet</span> and double <span class="hlt">sheet</span> Birkeland <span class="hlt">currents</span> during 555 passes during the summer and 408 passes during the winter. The single <span class="hlt">sheet</span> <span class="hlt">currents</span> are observed more frequently in the dayside of the auroral zone, and more often in summer than in winter. The intensities of both the single and double dayside <span class="hlt">currents</span> are found to be greater in the summer than in the winter by a factor of two, while the intensities of the double <span class="hlt">sheet</span> Birkeland <span class="hlt">currents</span> on the nightside do not show a significant difference from summer to winter. Both the single and double <span class="hlt">sheet</span> <span class="hlt">currents</span> are found at higher latitudes in the summer than in the winter on the dayside. Results suggest that the Birkeland <span class="hlt">current</span> intensities are controlled by the ionospheric conductivity in the polar region, and that the <span class="hlt">currents</span> close via the polar cap when the conductivity there is sufficiently high. It is also concluded that an important source of these <span class="hlt">currents</span> must be a voltage generator in the magnetosphere.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70031295','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70031295"><span>Nesting habitat relationships of sympatric Crested Caracaras, Red-<span class="hlt">tailed</span> Hawks, and White-<span class="hlt">tailed</span> Hawks in South Texas</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Actkinson, M.A.; Kuvlesky, W.P.; Boal, C.W.; Brennan, L.A.; Hernandez, F.</p> <p>2007-01-01</p> <p>We quantified nesting-site habitats for sympatric White-<span class="hlt">tailed</span> Hawks (Buteo albicaudatus) (n = 40), Red-<span class="hlt">tailed</span> Hawks (B. jamaicensis) (n = 39), and Crested Caracaras (Caracara cheriway) (n = 24) in the Coastal Sand Plain of south Texas. White-<span class="hlt">tailed</span> Hawks and Crested Caracara nest sites occurred in savannas, whereas Red-<span class="hlt">tailed</span> Hawk nest sites occurred in woodlands on the edge of savannas. White-<span class="hlt">tailed</span> Hawk nest sites were in shrubs and trees that were shorter (3.5 ?? 1.0 m) and had smaller canopy diameters (5.5 ?? 2.1 m) than those of Red-<span class="hlt">tailed</span> Hawks (10.1 ?? 2.0 m, 13.7 ?? 5.8 m) and Crested Caracaras (5.6 ?? 1.7 m, 8.5 ?? 3.5 m). Red-<span class="hlt">tailed</span> Hawk nest sites had higher woody densities (15.7 ?? 9.6 plants) and more woody cover (84 ?? 19%) than those of White-<span class="hlt">tailed</span> Hawks (5.6 ?? 5.8 plants, 20 ?? 21%) and Crested Caracaras (9.9 ?? 6.7 plants, 55 ?? 34%). Crested Caracara nest sites were in dense, multi-branched shrubs composed of more living material (97 ?? 3%) than those of White-<span class="hlt">tailed</span> (88 ?? 18%) and Red-<span class="hlt">tailed</span> hawks (88 ?? 18%). Nest sites of White-<span class="hlt">tailed</span> Hawks, Red-<span class="hlt">tailed</span> Hawks, and Crested Caracaras were similar to random samples from the surrounding habitat indicating that preferred nesting habitat was available for each of these species at least within 60 m of active nest sites. Nest tree height, along with woody plant and native grass cover best discriminated nest sites among the three raptor species. There was no overlap at Red-<span class="hlt">tailed</span> and White-<span class="hlt">tailed</span> hawk nest sites in vegetation structure, while Crested Caracara nests were in habitat intermediate between the two other species. Partitioning of nesting habitat may be how these raptor species co-exist at the broader landscape scale of our study area in the Coastal Sand Plain of Texas.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017Nanot..28Q5705S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017Nanot..28Q5705S"><span>Large patternable metal nanoparticle <span class="hlt">sheets</span> by photo/e-beam lithography</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Saito, Noboru; Wang, Pangpang; Okamoto, Koichi; Ryuzaki, Sou; Tamada, Kaoru</p> <p>2017-10-01</p> <p>Techniques for micro/nano-scale patterning of large metal nanoparticle <span class="hlt">sheets</span> can potentially be used to realize high-performance photoelectronic devices because the <span class="hlt">sheets</span> provide greatly enhanced electrical fields around the nanoparticles due to localized surface plasmon resonances. However, no single metal nanoparticle <span class="hlt">sheet</span> <span class="hlt">currently</span> exists with sufficient durability for conventional lithographical processes. Here, we report large photo and/or e-beam lithographic patternable metal nanoparticle <span class="hlt">sheets</span> with improved durability by incorporating molecular cross-linked structures between nanoparticles. The cross-linked structures were easily formed by a one-step chemical reaction; immersing a single nanoparticle <span class="hlt">sheet</span> consisting of core metals, to which capping molecules ionically bond, in a dithiol ethanol solution. The ligand exchange reaction processes were discussed in detail, and we demonstrated 20 μm wide line and space patterns, and a 170 nm wide line of the silver nanoparticle <span class="hlt">sheets</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20050029406','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20050029406"><span><span class="hlt">Tail</span> Buffeting</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Abdrashitov, G.</p> <p>1943-01-01</p> <p>An approximate theory of buffeting is here presented, based on the assumption of harmonic disturbing forces. Two cases of buffeting are considered: namely, for a <span class="hlt">tail</span> angle of attack greater and less than the stalling angle, respectively. On the basis of the tests conducted and the results of foreign investigators, a general analysis is given of the nature of the forced vibrations the possible load limits on the <span class="hlt">tail</span>, and the methods of elimination of buffeting.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/963066','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/963066"><span>Sharp-<span class="hlt">tailed</span> Grouse Restoration; Colville Tribes Restore Habitat for Sharp-<span class="hlt">tailed</span> Grouse, Annual Report 2002-2003.</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Whitney, Richard</p> <p>2004-01-01</p> <p>Columbian Sharp-<span class="hlt">Tailed</span> Grouse (Tympanuchus phasianellus columbianus) (CSTG) are an important traditional and cultural species to the Colville Confederated Tribes (CCT), Spokane Tribe of Indians (STOI), and other Tribes in the Region. They were once the most abundant upland bird in the Region. <span class="hlt">Currently</span>, the largest remaining population in Washington State occurs on the CCT Reservation in Okanogan County. Increasing agricultural practices and other land uses has contributed to the decline of sharp-<span class="hlt">tail</span> habitat and populations putting this species at risk. The decline of this species is not new (Yokum, 1952, Buss and Dziedzic, 1955, Zeigler, 1979, Meints 1991, and Crawfordmore » and Snyder 1994). The Tribes (CCT and STOI) are determined to protect, enhance and restore habitat for this species continued existence. When Grand Coulee and Chief Joseph Hydro-projects were constructed, inundated habitat used by this species was lost forever adding to overall decline. To compensate and prevent further habitat loss, the CCT proposed a project with Bonneville Power Administration (BPA) funding to address this species and their habitat requirements. The projects main focus is to address habitat utilized by the <span class="hlt">current</span> CSTG population and determine ways to protect, restore, and enhance habitats for the conservation of this species over time. The project went through the NPPC Review Process and was funded through FY03 by BPA. This report addresses part of the <span class="hlt">current</span> CCT effort to address the conservation of this species on the Colville Reservation.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20110008003','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20110008003"><span><span class="hlt">Current</span> <span class="hlt">Sheets</span> in the Corona and the Complexity of Slow Wind</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Antiochos, Spiro</p> <p>2010-01-01</p> <p>The origin of the slow solar wind has long been one of the most important problems in solar/heliospheric physics. Two observational constraints make this problem especially challenging. First, the slow wind has the composition of the closed-field corona, unlike the fast wind that originates on open field lines. Second, the slow wind has substantial angular extent, of order 30 degrees, which is much larger than the widths observed for streamer stalks or the widths expected theoretically for a dynamic heliospheric <span class="hlt">current</span> <span class="hlt">sheet</span>. We propose that the slow wind originates from an intricate network of narrow (possibly singular) open-field corridors that emanate from the polar coronal hole regions. Using topological arguments, we show that these corridors must be ubiquitous in the solar corona. The total solar eclipse in August 2008, near the lowest point of cycle 23 affords an ideal opportunity to test this theory by using the ultra-high resolution Predictive Science's (PSI) eclipse model for the corona and wind. Analysis of the PSI eclipse model demonstrates that the extent and scales of the open-field corridors can account for both the angular width of the slow wind and its closed-field composition. We discuss the implications of our slow wind theory for the structure of the corona and heliosphere at solar minimum and describe further observational and theoretical tests.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22043555-collisionless-distribution-function-relativistic-force-free-harris-sheet','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22043555-collisionless-distribution-function-relativistic-force-free-harris-sheet"><span>Collisionless distribution function for the relativistic force-free Harris <span class="hlt">sheet</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Stark, C. R.; Neukirch, T.</p> <p></p> <p>A self-consistent collisionless distribution function for the relativistic analogue of the force-free Harris <span class="hlt">sheet</span> is presented. This distribution function is the relativistic generalization of the distribution function for the non-relativistic collisionless force-free Harris <span class="hlt">sheet</span> recently found by Harrison and Neukirch [Phys. Rev. Lett. 102, 135003 (2009)], as it has the same dependence on the particle energy and canonical momenta. We present a detailed calculation which shows that the proposed distribution function generates the required <span class="hlt">current</span> density profile (and thus magnetic field profile) in a frame of reference in which the electric potential vanishes identically. The connection between the parameters ofmore » the distribution function and the macroscopic parameters such as the <span class="hlt">current</span> <span class="hlt">sheet</span> thickness is discussed.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017MS%26E..261a2019H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017MS%26E..261a2019H"><span>Research on Long <span class="hlt">Tail</span> Recommendation Algorithm</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hu, Xuezhi; Zhang, Chuang; Wu, Ming; Zeng, Yang</p> <p>2017-10-01</p> <p>Most recommendation systems in the major electronic commerce platforms are influenced by the long <span class="hlt">tail</span> effect more or less. There are sufficient researches of how to assess recommendation effect while no criteria to evaluate long <span class="hlt">tail</span> recommendation rate. In this study, we first discussed the existing problems of recommending long <span class="hlt">tail</span> products through specific experiments. Then we proposed a long <span class="hlt">tail</span> evaluation criteria and compared the performance in long <span class="hlt">tail</span> recommendation between different models.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JPhCS.669a2055S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JPhCS.669a2055S"><span>Fractal structure of low-temperature plasma of arc discharge as a consequence of the interaction of <span class="hlt">current</span> <span class="hlt">sheets</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Smolanov, N. A.</p> <p>2016-01-01</p> <p>The structure of the particles deposited from the plasma arc discharge were studied. The flow of plasma spreading from the cathode spot to the walls of the vacuum chamber. Electric and magnetic fields to influence the plasma flow. The fractal nature of the particles from the plasma identified by small-angle X-ray scattering. Possible cause of their formation is due to the instability of the growth front and nonequilibrium conditions for their production - a high speed transition of the vapor-liquid-solid or vapor - crystal. The hypothesis of a plasma arc containing dust particles <span class="hlt">current</span> <span class="hlt">sheets</span> was proposed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5056738','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5056738"><span>A Tale of <span class="hlt">Tails</span>: Dissecting the Enhancing Effect of <span class="hlt">Tailed</span> Primers in Real-Time PCR</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Vandenbussche, Frank; Mathijs, Elisabeth; Lefebvre, David; De Clercq, Kris; Van Borm, Steven</p> <p>2016-01-01</p> <p>Non-specific <span class="hlt">tail</span> sequences are often added to the 5’-terminus of primers to improve the robustness and overall performance of diagnostic assays. Despite the widespread use of <span class="hlt">tailed</span> primers, the underlying working mechanism is not well understood. To address this problem, we conducted a detailed in vitro and in silico analysis of the enhancing effect of primer <span class="hlt">tailing</span> on 2 well-established foot-and-mouth disease virus (FMDV) RT-qPCR assays using an FMDV reference panel. <span class="hlt">Tailing</span> of the panFMDV-5UTR primers mainly affected the shape of the amplification curves. Modelling of the raw fluorescence data suggested a reduction of the amplification efficiency due to the accumulation of inhibitors. In depth analysis of PCR products indeed revealed the rapid accumulation of forward-primer derived artefacts. More importantly, <span class="hlt">tailing</span> of the forward primer delayed artefacts formation and concomitantly restored the sigmoidal shape of the amplification curves. Our analysis also showed that primer <span class="hlt">tailing</span> can alter utilisation patterns of degenerate primers and increase the number of primer variants that are able to participate in the reaction. The impact of <span class="hlt">tailed</span> primers was less pronounced in the panFMDV-3D assay with only 5 out of 50 isolates showing a clear shift in Cq values. Sequence analysis of the target region of these 5 isolates revealed several mutations in the inter-primer region that extend an existing hairpin structure immediately downstream of the forward primer binding site. Stabilisation of the forward primer with either a <span class="hlt">tail</span> sequence or cationic spermine units restored the sensitivity of the assay, which suggests that the enhancing effect in the panFMDV-3D assay is due to a more efficient extension of the forward primer. ur results show that primer <span class="hlt">tailing</span> can alter amplification through various mechanisms that are determined by both the assay and target region. These findings expand our understanding of primer <span class="hlt">tailing</span> and should enable a more targeted and</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19930072244&hterms=Plasma+Ring&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3DPlasma%2BRing','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19930072244&hterms=Plasma+Ring&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3DPlasma%2BRing"><span>Energy content of stormtime ring <span class="hlt">current</span> from phase space mapping simulations</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Chen, Margaret W.; Schulz, Michael; Lyons, Larry R.</p> <p>1993-01-01</p> <p>We perform a phase space mapping study to estimate the enhancement in energy content that results from stormtime particle transport in the equatorial magnetosphere. Our pre-storm phase space distribution is based on a steady-state transport model. Using results from guiding-center simulations of ion transport during model storms having main phases of 3 hr, 6 hr, and 12 hr, we map phase space distributions of ring <span class="hlt">current</span> protons from the pre-storm distribution in accordance with Liouville's theorem. We find that transport can account for the entire ten to twenty-fold increase in magnetospheric particle energy content typical of a major storm if a realistic stormtime enhancement of the phase space density f is imposed at the nightside <span class="hlt">tail</span> plasma <span class="hlt">sheet</span> (represented by an enhancement of f at the neutral line in our model).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19860030106&hterms=vlahos&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAuthor-Name%26N%3D0%26No%3D20%26Ntt%3Dvlahos','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19860030106&hterms=vlahos&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAuthor-Name%26N%3D0%26No%3D20%26Ntt%3Dvlahos"><span>Runaway <span class="hlt">tails</span> in magnetized plasmas</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Moghaddam-Taaheri, E.; Vlahos, L.; Rowland, H. L.; Papadopoulos, K.</p> <p>1985-01-01</p> <p>The evolution of a runaway <span class="hlt">tail</span> driven by a dc electric field in a magnetized plasma is analyzed. Depending on the strength of the electric field and the ratio of plasma to gyrofrequency, there are three different regimes in the evolution of the <span class="hlt">tail</span>. The <span class="hlt">tail</span> can be (1) stable with electrons accelerated to large parallel velocities, (2) unstable to Cerenkov resonance because of the depletion of the bulk and the formation of a positive slope, (3) unstable to the anomalous Doppler resonance instability driven by the large velocity anisotropy in the <span class="hlt">tail</span>. Once an instability is triggered (Cerenkov or anomalous Doppler resonance) the <span class="hlt">tail</span> relaxes into an isotropic distribution. The role of a convection type loss term is also discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018RvGeo..56..142P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018RvGeo..56..142P"><span>Ocean Tide Influences on the Antarctic and Greenland Ice <span class="hlt">Sheets</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Padman, Laurie; Siegfried, Matthew R.; Fricker, Helen A.</p> <p>2018-03-01</p> <p>Ocean tides are the main source of high-frequency variability in the vertical and horizontal motion of ice <span class="hlt">sheets</span> near their marine margins. Floating ice shelves, which occupy about three quarters of the perimeter of Antarctica and the termini of four outlet glaciers in northern Greenland, rise and fall in synchrony with the ocean tide. Lateral motion of floating and grounded portions of ice <span class="hlt">sheets</span> near their marine margins can also include a tidal component. These tide-induced signals provide insight into the processes by which the oceans can affect ice <span class="hlt">sheet</span> mass balance and dynamics. In this review, we summarize in situ and satellite-based measurements of the tidal response of ice shelves and grounded ice, and spatial variability of ocean tide heights and <span class="hlt">currents</span> around the ice <span class="hlt">sheets</span>. We review sensitivity of tide heights and <span class="hlt">currents</span> as ocean geometry responds to variations in sea level, ice shelf thickness, and ice <span class="hlt">sheet</span> mass and extent. We then describe coupled ice-ocean models and analytical glacier models that quantify the effect of ocean tides on lower-frequency ice <span class="hlt">sheet</span> mass loss and motion. We suggest new observations and model developments to improve the representation of tides in coupled models that are used to predict future ice <span class="hlt">sheet</span> mass loss and the associated contribution to sea level change. The most critical need is for new data to improve maps of bathymetry, ice shelf draft, spatial variability of the drag coefficient at the ice-ocean interface, and higher-resolution models with improved representation of tidal energy sinks.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28873065','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28873065"><span>Mechanisms of <span class="hlt">tail</span> resorption during anuran metamorphosis.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Nakai, Yuya; Nakajima, Keisuke; Yaoita, Yoshio</p> <p>2017-09-26</p> <p>Amphibian metamorphosis has historically attracted a good deal of scientific attention owing to its dramatic nature and easy observability. However, the genetic mechanisms of amphibian metamorphosis have not been thoroughly examined using modern techniques such as gene cloning, DNA sequencing, polymerase chain reaction or genomic editing. Here, we review the <span class="hlt">current</span> state of knowledge regarding molecular mechanisms underlying tadpole <span class="hlt">tail</span> resorption.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22299645-dynamic-topology-flux-rope-evolution-during-non-linear-tearing-null-point-current-sheets','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22299645-dynamic-topology-flux-rope-evolution-during-non-linear-tearing-null-point-current-sheets"><span>Dynamic topology and flux rope evolution during non-linear tearing of 3D null point <span class="hlt">current</span> <span class="hlt">sheets</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Wyper, P. F., E-mail: peterw@maths.dundee.ac.uk; Pontin, D. I., E-mail: dpontin@maths.dundee.ac.uk</p> <p>2014-10-15</p> <p>In this work, the dynamic magnetic field within a tearing-unstable three-dimensional <span class="hlt">current</span> <span class="hlt">sheet</span> about a magnetic null point is described in detail. We focus on the evolution of the magnetic null points and flux ropes that are formed during the tearing process. Generally, we find that both magnetic structures are created prolifically within the layer and are non-trivially related. We examine how nulls are created and annihilated during bifurcation processes, and describe how they evolve within the <span class="hlt">current</span> layer. The type of null bifurcation first observed is associated with the formation of pairs of flux ropes within the <span class="hlt">current</span> layer.more » We also find that new nulls form within these flux ropes, both following internal reconnection and as adjacent flux ropes interact. The flux ropes exhibit a complex evolution, driven by a combination of ideal kinking and their interaction with the outflow jets from the main layer. The finite size of the unstable layer also allows us to consider the wider effects of flux rope generation. We find that the unstable <span class="hlt">current</span> layer acts as a source of torsional magnetohydrodynamic waves and dynamic braiding of magnetic fields. The implications of these results to several areas of heliophysics are discussed.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2012-title49-vol4/pdf/CFR-2012-title49-vol4-sec236-338.pdf','CFR2012'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2012-title49-vol4/pdf/CFR-2012-title49-vol4-sec236-338.pdf"><span>49 CFR 236.338 - Mechanical locking required in accordance with locking <span class="hlt">sheet</span> and dog chart.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2012&page.go=Go">Code of Federal Regulations, 2012 CFR</a></p> <p></p> <p>2012-10-01</p> <p>... locking <span class="hlt">sheet</span> and dog chart. 236.338 Section 236.338 Transportation Other Regulations Relating to... in accordance with locking <span class="hlt">sheet</span> and dog chart. Mechanical locking shall be in accordance with locking <span class="hlt">sheet</span> and dog chart <span class="hlt">currently</span> in effect. ...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2014-title49-vol4/pdf/CFR-2014-title49-vol4-sec236-338.pdf','CFR2014'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2014-title49-vol4/pdf/CFR-2014-title49-vol4-sec236-338.pdf"><span>49 CFR 236.338 - Mechanical locking required in accordance with locking <span class="hlt">sheet</span> and dog chart.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2014&page.go=Go">Code of Federal Regulations, 2014 CFR</a></p> <p></p> <p>2014-10-01</p> <p>... locking <span class="hlt">sheet</span> and dog chart. 236.338 Section 236.338 Transportation Other Regulations Relating to... in accordance with locking <span class="hlt">sheet</span> and dog chart. Mechanical locking shall be in accordance with locking <span class="hlt">sheet</span> and dog chart <span class="hlt">currently</span> in effect. ...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2013-title49-vol4/pdf/CFR-2013-title49-vol4-sec236-338.pdf','CFR2013'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2013-title49-vol4/pdf/CFR-2013-title49-vol4-sec236-338.pdf"><span>49 CFR 236.338 - Mechanical locking required in accordance with locking <span class="hlt">sheet</span> and dog chart.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2013&page.go=Go">Code of Federal Regulations, 2013 CFR</a></p> <p></p> <p>2013-10-01</p> <p>... locking <span class="hlt">sheet</span> and dog chart. 236.338 Section 236.338 Transportation Other Regulations Relating to... in accordance with locking <span class="hlt">sheet</span> and dog chart. Mechanical locking shall be in accordance with locking <span class="hlt">sheet</span> and dog chart <span class="hlt">currently</span> in effect. ...</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_18 --> <div id="page_19" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="361"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2011-title49-vol4/pdf/CFR-2011-title49-vol4-sec236-338.pdf','CFR2011'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2011-title49-vol4/pdf/CFR-2011-title49-vol4-sec236-338.pdf"><span>49 CFR 236.338 - Mechanical locking required in accordance with locking <span class="hlt">sheet</span> and dog chart.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2011&page.go=Go">Code of Federal Regulations, 2011 CFR</a></p> <p></p> <p>2011-10-01</p> <p>... locking <span class="hlt">sheet</span> and dog chart. 236.338 Section 236.338 Transportation Other Regulations Relating to... in accordance with locking <span class="hlt">sheet</span> and dog chart. Mechanical locking shall be in accordance with locking <span class="hlt">sheet</span> and dog chart <span class="hlt">currently</span> in effect. ...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2010-title49-vol4/pdf/CFR-2010-title49-vol4-sec236-338.pdf','CFR'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2010-title49-vol4/pdf/CFR-2010-title49-vol4-sec236-338.pdf"><span>49 CFR 236.338 - Mechanical locking required in accordance with locking <span class="hlt">sheet</span> and dog chart.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2010&page.go=Go">Code of Federal Regulations, 2010 CFR</a></p> <p></p> <p>2010-10-01</p> <p>... locking <span class="hlt">sheet</span> and dog chart. 236.338 Section 236.338 Transportation Other Regulations Relating to... in accordance with locking <span class="hlt">sheet</span> and dog chart. Mechanical locking shall be in accordance with locking <span class="hlt">sheet</span> and dog chart <span class="hlt">currently</span> in effect. ...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22666061-reconnection-properties-large-scale-current-sheets-during-coronal-mass-ejection-eruptions','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22666061-reconnection-properties-large-scale-current-sheets-during-coronal-mass-ejection-eruptions"><span>RECONNECTION PROPERTIES OF LARGE-SCALE <span class="hlt">CURRENT</span> <span class="hlt">SHEETS</span> DURING CORONAL MASS EJECTION ERUPTIONS</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Lynch, B. J.; Kazachenko, M. D.; Edmondson, J. K.</p> <p>2016-07-20</p> <p>We present a detailed analysis of the properties of magnetic reconnection at large-scale <span class="hlt">current</span> <span class="hlt">sheets</span> (CSs) in a high cadence version of the Lynch and Edmondson 2.5D MHD simulation of sympathetic magnetic breakout eruptions from a pseudostreamer source region. We examine the resistive tearing and break-up of the three main CSs into chains of X- and O-type null points and follow the dynamics of magnetic island growth, their merging, transit, and ejection with the reconnection exhaust. For each CS, we quantify the evolution of the length-to-width aspect ratio (up to ∼100:1), Lundquist number (∼10{sup 3}), and reconnection rate (inflow-to-outflow ratiosmore » reaching ∼0.40). We examine the statistical and spectral properties of the fluctuations in the CSs resulting from the plasmoid instability, including the distribution of magnetic island area, mass, and flux content. We show that the temporal evolution of the spectral index of the reconnection-generated magnetic energy density fluctuations appear to reflect global properties of the CS evolution. Our results are in excellent agreement with recent, high-resolution reconnection-in-a-box simulations even though our CSs’ formation, growth, and dynamics are intrinsically coupled to the global evolution of sequential sympathetic coronal mass ejection eruptions.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19990027438&hterms=paper+planes&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dpaper%2Bplanes','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19990027438&hterms=paper+planes&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dpaper%2Bplanes"><span>The Distant <span class="hlt">Tail</span> at 200 R(sub E): Comparison Between Geotail Observations and the Results from a Global Magnetohydrodynamic Simulation</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Berchem, J.; Raeder, J.; Ashour-Abdalla, M.; Frank, L. A.; Paterson, W. R.; Ackerson, K. L.; Kokubun, S.; Yamamoto, T.; Lepping, R. P.</p> <p>1998-01-01</p> <p>This paper reports a comparison between Geotail observations of plasmas and magnetic fields at 200 R(sub E) in the Earth's magnetotail with results from a time-dependent, global magnetohydrodynamic simulation of the interaction of the solar wind with the magnetosphere. The study focuses on observations from July 7, 1993, during which the Geotail spacecraft crossed the distant <span class="hlt">tail</span> magnetospheric boundary several times while the interplanetary magnetic field (IMF) was predominantly northward and was marked by slow rotations of its clock angle. Simultaneous IMP 8 observations of solar wind ions and the IMF were used as driving input for the MHD simulation, and the resulting time series were compared directly with those from the Geotail spacecraft. The very good agreement found provided the basis for an investigation of the response of the distant <span class="hlt">tail</span> associated with the clock angle of the IMF. Results from the simulation show that the stresses imposed by the draping of magnetosheath field lines and the asymmetric removal of magnetic flux tailward of the cusps altered considerably the shape of the distant <span class="hlt">tail</span> as the solar wind discontinuities convected downstream of Earth. As a result, the cross section of the distant <span class="hlt">tail</span> was considerably flattened along the direction perpendicular to the IMF clock angle, the direction of the neutral <span class="hlt">sheet</span> following that of the IMF. The simulation also revealed that the combined action of magnetic reconnection and the slow rotation of the IMF clock angle led to a braiding of the distant <span class="hlt">tail</span>'s magnetic field lines along the axis of the <span class="hlt">tail</span>, with the plane of the braid lying in the direction of the IMF.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22472500-possible-mechanism-enhancement-maintenance-shear-magnetic-field-component-current-sheet-earths-magnetotail','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22472500-possible-mechanism-enhancement-maintenance-shear-magnetic-field-component-current-sheet-earths-magnetotail"><span>A possible mechanism of the enhancement and maintenance of the shear magnetic field component in the <span class="hlt">current</span> <span class="hlt">sheet</span> of the Earth’s magnetotail</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Grigorenko, E. E., E-mail: elenagrigorenko2003@yahoo.com; Malova, H. V., E-mail: hmalova@yandex.ru; Malykhin, A. Yu., E-mail: anmaurdreg@gmail.com</p> <p>2015-01-15</p> <p>The influence of the shear magnetic field component, which is directed along the electric <span class="hlt">current</span> in the <span class="hlt">current</span> <span class="hlt">sheet</span> (CS) of the Earth’s magnetotail and enhanced near the neutral plane of the CS, on the nonadiabatic dynamics of ions interacting with the CS is studied. The results of simulation of the nonadiabatic ion motion in the prescribed magnetic configuration similar to that observed in the magnetotail CS by the CLUSTER spacecraft demonstrated that, in the presence of some initial shear magnetic field, the north-south asymmetry in the ion reflection/refraction in the CS is observed. This asymmetry leads to the formationmore » of an additional <span class="hlt">current</span> system formed by the oppositely directed electric <span class="hlt">currents</span> flowing in the northern and southern parts of the plasma <span class="hlt">sheet</span> in the planes tangential to the CS plane and in the direction perpendicular to the direction of the electric <span class="hlt">current</span> in the CS. The formation of this <span class="hlt">current</span> system perhaps is responsible for the enhancement and further maintenance of the shear magnetic field near the neutral plane of the CS. The CS structure and ion dynamics observed in 17 intervals of the CS crossings by the CLUSTER spacecraft is analyzed. In these intervals, the shear magnetic field was increased near the neutral plane of the CS, so that the bell-shaped spatial distribution of this field across the CS plane was observed. The results of the present analysis confirm the suggested scenario of the enhancement of the shear magnetic field near the neutral plane of the CS due to the peculiarities of the nonadiabatic ion dynamics.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29311320','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29311320"><span>Power law <span class="hlt">tails</span> in phylogenetic systems.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Qin, Chongli; Colwell, Lucy J</p> <p>2018-01-23</p> <p>Covariance analysis of protein sequence alignments uses coevolving pairs of sequence positions to predict features of protein structure and function. However, <span class="hlt">current</span> methods ignore the phylogenetic relationships between sequences, potentially corrupting the identification of covarying positions. Here, we use random matrix theory to demonstrate the existence of a power law <span class="hlt">tail</span> that distinguishes the spectrum of covariance caused by phylogeny from that caused by structural interactions. The power law is essentially independent of the phylogenetic tree topology, depending on just two parameters-the sequence length and the average branch length. We demonstrate that these power law <span class="hlt">tails</span> are ubiquitous in the large protein sequence alignments used to predict contacts in 3D structure, as predicted by our theory. This suggests that to decouple phylogenetic effects from the interactions between sequence distal sites that control biological function, it is necessary to remove or down-weight the eigenvectors of the covariance matrix with largest eigenvalues. We confirm that truncating these eigenvectors improves contact prediction.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/20034314-new-idea-transporting-tailings-logs-tailings-slurry-pipeline-innovation-technology-mining-waste-fill-method','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/20034314-new-idea-transporting-tailings-logs-tailings-slurry-pipeline-innovation-technology-mining-waste-fill-method"><span>The new idea of transporting <span class="hlt">tailings</span>-logs in <span class="hlt">tailings</span> slurry pipeline and the innovation of technology of mining waste-fill method</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Lin Yu; Wang Fuji; Tao Yan</p> <p>2000-07-01</p> <p>This paper introduced a new idea of transporting mine <span class="hlt">tailings</span>-logs in mine <span class="hlt">tailings</span>-slurry pipeline and a new technology of mine cemented filing of <span class="hlt">tailings</span>-logs with <span class="hlt">tailings</span>-slurry. The hydraulic principles, the compaction of <span class="hlt">tailings</span>-logs and the mechanic function of fillbody of <span class="hlt">tailings</span>-logs cemented by <span class="hlt">tailings</span>-slurry have been discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSM33B2657G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSM33B2657G"><span>An embedding structure of the cross-<span class="hlt">tail</span> CSs and its relation to the ion composition according to MAVEN observations in the Martian magnetotai</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Grigorenko, E. E.; Shuvalov, S. D.; Malova, H. V.; Zelenyi, L. M.</p> <p>2017-12-01</p> <p>The multilayered (embedded) <span class="hlt">Current</span> <span class="hlt">Sheets</span> (CS) are often observed in the Earth's magnetotail. Simulations based on quasi-adiabatic dynamics of different ion components showed that the observed embedding structures can be reconstructed by taking into account the net electric <span class="hlt">currents</span> carried by ions with different masses and, thus, with different gyroradii. The last determines the spatial scales of the corresponding <span class="hlt">current</span> layers. The embedding can be quantitatively described by the ratio of the magnetic field value at the edges of a thin embedded layer Bext to the value of the magnetic field outside a thick CS, B0. For the Earth's magnetotail it was shown that there is a relation between the Bext/B0 and the relative densities of heavy and light ion components. In the Martian magnetotail the embedding feature is also often observed in the cross-<span class="hlt">tail</span> CS formed by the draping of the IMF field lines. The analysis of 100 CS crossings by MAVEN spacecraft showed that in the Martian magnetotail the relation between the embedding characteristics and ion composition is similar to the one observed in the Earth's magnetotail and the spatial scales of the embedded layers are defined by the gyroradii of the <span class="hlt">current</span> carrying ion component.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19900041103&hterms=capture+heart&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dcapture%2Bheart','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19900041103&hterms=capture+heart&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dcapture%2Bheart"><span>High resolution flow field prediction for <span class="hlt">tail</span> rotor aeroacoustics</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Quackenbush, Todd R.; Bliss, Donald B.</p> <p>1989-01-01</p> <p>The prediction of <span class="hlt">tail</span> rotor noise due to the impingement of the main rotor wake poses a significant challenge to <span class="hlt">current</span> analysis methods in rotorcraft aeroacoustics. This paper describes the development of a new treatment of the <span class="hlt">tail</span> rotor aerodynamic environment that permits highly accurate resolution of the incident flow field with modest computational effort relative to alternative models. The new approach incorporates an advanced full-span free wake model of the main rotor in a scheme which reconstructs high-resolution flow solutions from preliminary, computationally inexpensive simulations with coarse resolution. The heart of the approach is a novel method for using local velocity correction terms to capture the steep velocity gradients characteristic of the vortex-dominated incident flow. Sample calculations have been undertaken to examine the principal types of interactions between the <span class="hlt">tail</span> rotor and the main rotor wake and to examine the performance of the new method. The results of these sample problems confirm the success of this approach in capturing the high-resolution flows necessary for analysis of rotor-wake/rotor interactions with dramatically reduced computational cost. Computations of radiated sound are also carried out that explore the role of various portions of the main rotor wake in generating <span class="hlt">tail</span> rotor noise.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/FR-2013-10-03/pdf/2013-24268.pdf','FEDREG'); return false;" href="https://www.gpo.gov/fdsys/pkg/FR-2013-10-03/pdf/2013-24268.pdf"><span>78 FR 61331 - Freshwater Crawfish <span class="hlt">Tail</span> Meat From the People's Republic of China: Preliminary Results of...</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collection.action?collectionCode=FR">Federal Register 2010, 2011, 2012, 2013, 2014</a></p> <p></p> <p>2013-10-03</p> <p>... Meat From the People's Republic of China: Preliminary Results of Antidumping Duty Administrative Review... review and new shipper review of the antidumping duty order on freshwater crawfish <span class="hlt">tail</span> meat from the... antidumping duty order is freshwater crawfish <span class="hlt">tail</span> meat, which is <span class="hlt">currently</span> classified in the Harmonized...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4767187','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4767187"><span>Heavy-<span class="hlt">Tailed</span> Fluctuations in the Spiking Output Intensity of Semiconductor Lasers with Optical Feedback</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p></p> <p>2016-01-01</p> <p>Although heavy-<span class="hlt">tailed</span> fluctuations are ubiquitous in complex systems, a good understanding of the mechanisms that generate them is still lacking. Optical complex systems are ideal candidates for investigating heavy-<span class="hlt">tailed</span> fluctuations, as they allow recording large datasets under controllable experimental conditions. A dynamical regime that has attracted a lot of attention over the years is the so-called low-frequency fluctuations (LFFs) of semiconductor lasers with optical feedback. In this regime, the laser output intensity is characterized by abrupt and apparently random dropouts. The statistical analysis of the inter-dropout-intervals (IDIs) has provided many useful insights into the underlying dynamics. However, the presence of large temporal fluctuations in the IDI sequence has not yet been investigated. Here, by applying fluctuation analysis we show that the experimental distribution of IDI fluctuations is heavy-<span class="hlt">tailed</span>, and specifically, is well-modeled by a non-Gaussian stable distribution. We find a good qualitative agreement with simulations of the Lang-Kobayashi model. Moreover, we uncover a transition from a less-heavy-<span class="hlt">tailed</span> state at low pump <span class="hlt">current</span> to a more-heavy-<span class="hlt">tailed</span> state at higher pump <span class="hlt">current</span>. Our results indicate that fluctuation analysis can be a useful tool for investigating the output signals of complex optical systems; it can be used for detecting underlying regime shifts, for model validation and parameter estimation. PMID:26901346</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19730010086','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19730010086"><span>Magnetic field dissipation in D-<span class="hlt">sheets</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Burlaga, L. F.; Scudder, J. D.</p> <p>1973-01-01</p> <p>The effects of magnetic field annihilation at a tangential or rotational discontinuity in a resistive plasma are examined. The magnetic field intensity profile depends on (1) the field intensities far from the <span class="hlt">current</span> <span class="hlt">sheet</span> (+ and - infinity), (2) the angle between the two intensities, and (3) the electrical resistivity. For a tangential discontinuity, the theory predicts a depression in B, centered at the discontinuity, and it predicts a monotonic transition. The theory provides satisfactory fits to the magnetic field intensity and proton temperature profiles observed for two extremely broad D-<span class="hlt">sheets</span> in the solar wind. Assuming a diffusion time 10 days, one obtains effective resistivities or approximately = 3 x 10 to the 12th power and 2 x 10 to the 13th power emu for the D-<span class="hlt">sheets</span>. Either resistivity at directional discontinuities is much lower than 10 to the 12th power emu or annihilation does not always occur at discontinuities.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1184758','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/1184758"><span>Eddy <span class="hlt">current</span> thickness measurement apparatus</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Rosen, Gary J.; Sinclair, Frank; Soskov, Alexander; Buff, James S.</p> <p>2015-06-16</p> <p>A <span class="hlt">sheet</span> of a material is disposed in a melt of the material. The <span class="hlt">sheet</span> is formed using a cooling plate in one instance. An exciting coil and sensing coil are positioned downstream of the cooling plate. The exciting coil and sensing coil use eddy <span class="hlt">currents</span> to determine a thickness of the solid <span class="hlt">sheet</span> on top of the melt.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28005353','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28005353"><span>Ionic Liquids with Symmetric Diether <span class="hlt">Tails</span>: Bulk and Vacuum-Liquid Interfacial Structures.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hettige, Jeevapani J; Amith, Weththasinghage D; Castner, Edward W; Margulis, Claudio J</p> <p>2017-01-12</p> <p>The behavior in the bulk and at interfaces of biphilic ionic liquids in which either the cation or anion possesses moderately long alkyl <span class="hlt">tails</span> is to a significant degree well understood. Less clear is what happens when both the cation and anion possess <span class="hlt">tails</span> that are not apolar, such as in the case of ether functionalities. The <span class="hlt">current</span> article discusses the structural characteristics of C2OC2OC2-mim + /C2OC2OC2-OSO 3 - in the bulk and at the vacuum interface. We find that the vacuum interface affects only the nanometer length scale. This is in contrast to what we have recently found in ( J. Phys. Chem. Lett. , 2016 , 7 ( 19 ), 3785 - -3790 ) for isoelectronic C[8]-mim + /C[8]-OSO 3 - , where the interface effect is long ranged. Interestingly, ions with the diether <span class="hlt">tail</span> functionality still favor the <span class="hlt">tail</span>-outward orientation at the vacuum interface and the bulk phase preserves the alternation between charged networks and <span class="hlt">tails</span> that is commonly observed for biphilic ionic liquids. However, such alternation is less well-defined and results in a significantly diminished first sharp diffraction peak in the bulk liquid structure function.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23064963','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23064963"><span>Design, construction and management of <span class="hlt">tailings</span> storage facilities for surface disposal in China: case studies of failures.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wei, Zuoan; Yin, Guangzhi; Wang, J G; Wan, Ling; Li, Guangzhi</p> <p>2013-01-01</p> <p>Rapid development of China's economy demands for more mineral resources. At the same time, a vast quantity of mine <span class="hlt">tailings</span>, as the waste byproduct of mining and mineral processing, is being produced in huge proportions. <span class="hlt">Tailings</span> impoundments play an important role in the practical surface disposal of these large quantities of mining waste. Historically, <span class="hlt">tailings</span> were relatively small in quantity and had no commercial value, thus little attention was paid to their disposal. The <span class="hlt">tailings</span> were preferably discharged near the mines and few <span class="hlt">tailings</span> storage facilities were constructed in mainland China. This situation has significantly changed since 2000, because the Chinese economy is growing rapidly and Chinese regulations and legislation require that <span class="hlt">tailings</span> disposal systems must be ready before the mining operation begins. Consequently, data up to 2008 shows that more than 12 000 <span class="hlt">tailings</span> storage facilities have been built in China. This paper reviews the history of <span class="hlt">tailings</span> disposal in China, discusses three cases of <span class="hlt">tailings</span> dam failures and explores failure mechanisms, and the procedures commonly used in China for planning, design, construction and management of <span class="hlt">tailings</span> impoundments. This paper also discusses the <span class="hlt">current</span> situation, shortcomings and key weaknesses, as well as future development trends for <span class="hlt">tailings</span> storage facilities in China.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22493810-two-fluid-study-oblique-tearing-modes-force-free-current-sheet','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22493810-two-fluid-study-oblique-tearing-modes-force-free-current-sheet"><span>A two-fluid study of oblique tearing modes in a force-free <span class="hlt">current</span> <span class="hlt">sheet</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Akçay, Cihan, E-mail: akcay@lanl.gov; Daughton, William; Lukin, Vyacheslav S.</p> <p>2016-01-15</p> <p>Kinetic simulations have demonstrated that three-dimensional reconnection in collisionless regimes proceeds through the formation and interaction of magnetic flux ropes, which are generated due to the growth of tearing instabilities at multiple resonance surfaces. Since kinetic simulations are intrinsically expensive, it is desirable to explore the feasibility of reduced two-fluid models to capture this complex evolution, particularly, in the strong guide field regime, where two-fluid models are better justified. With this goal in mind, this paper compares the evolution of the collisionless tearing instability in a force-free <span class="hlt">current</span> <span class="hlt">sheet</span> with a two-fluid model and fully kinetic simulations. Our results indicatemore » that the most unstable modes are oblique for guide fields larger than the reconnecting field, in agreement with the kinetic results. The standard two-fluid tearing theory is extended to address the tearing instability at oblique angles. The resulting theory yields a flat oblique spectrum and underestimates the growth of oblique modes in a similar manner to kinetic theory relative to kinetic simulations.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22667237-voyager-observations-magnetic-sectors-heliospheric-current-sheet-crossings-outer-heliosphere','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22667237-voyager-observations-magnetic-sectors-heliospheric-current-sheet-crossings-outer-heliosphere"><span>VOYAGER OBSERVATIONS OF MAGNETIC SECTORS AND HELIOSPHERIC <span class="hlt">CURRENT</span> <span class="hlt">SHEET</span> CROSSINGS IN THE OUTER HELIOSPHERE</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Richardson, J. D.; Burlaga, L. F.; Drake, J. F.</p> <p></p> <p>Voyager 1 ( V1 ) has passed through the heliosheath and is in the local interstellar medium. Voyager 2 ( V2 ) has been in the heliosheath since 2007. The role of reconnection in the heliosheath is under debate; compression of the heliospheric <span class="hlt">current</span> <span class="hlt">sheets</span> (HCS) in the heliosheath could lead to rapid reconnection and a reconfiguration of the magnetic field topology. This paper compares the expected and actual amounts of time the Voyager spacecraft observe each magnetic sector and the number of HCS crossings. The predicted and observed values generally agree well. One exception is at Voyager 1 inmore » 2008 and 2009, where the distribution of sectors is more equal than expected and the number of HCS crossings is small. Two other exceptions are at V1 in 2011–2012 and at V2 in 2012, when the spacecraft are in the opposite magnetic sector less than expected and see fewer HCS crossings than expected. These features are consistent with those predicted for reconnection, and consequently searches for other reconnection signatures should focus on these times.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1240683-two-fluid-study-oblique-tearing-modes-force-free-current-sheet','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1240683-two-fluid-study-oblique-tearing-modes-force-free-current-sheet"><span>A two-fluid study of oblique tearing modes in a force-free <span class="hlt">current</span> <span class="hlt">sheet</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Akçay, Cihan; Daughton, William; Lukin, Vyacheslav S.; ...</p> <p>2016-01-01</p> <p>Kinetic simulations have demonstrated that three-dimensional reconnection in collisionless regimes proceeds through the formation and interaction of magnetic flux ropes, which are generated due to the growth of tearing instabilities at multiple resonance surfaces. Because kinetic simulations are intrinsically expensive, it is desirable to explore the feasibility of reduced two-fluid models to capture this complex evolution, particularly, in the strong guide field regime, where two-fluid models are better justified. With this goal in mind, this paper compares the evolution of the collisionless tearing instability in a force-free <span class="hlt">current</span> <span class="hlt">sheet</span> with a two-fluid model and fully kinetic simulations. Our results indicatemore » that the most unstable modes are oblique for guide fields larger than the reconnecting field, in agreement with the kinetic results. The standard two-fluid tearing theory is extended to address the tearing instability at oblique angles. As a results this theory yields a flat oblique spectrum and underestimates the growth of oblique modes in a similar manner to kinetic theory relative to kinetic simulations.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA11076.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA11076.html"><span>Exploring Mercury <span class="hlt">Tail</span></span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2008-08-26</p> <p>As the MESSENGER spacecraft approached Mercury, the UVVS field of view was scanned across the planet's exospheric "<span class="hlt">tail</span>," which is produced by the solar wind pushing Mercury's exosphere (the planet's extremely thin atmosphere) outward. This figure, recently published in Science magazine, shows a map of the distribution of sodium atoms as they stream away from the planet (see PIA10396); red and yellow colors represent a higher abundance of sodium than darker shades of blue and purple, as shown in the colored scale bar, which gives the brightness intensity in units of kiloRayleighs. The escaping atoms eventually form a comet-like <span class="hlt">tail</span> that extends in the direction opposite that of the Sun for many planetary radii. The small squares outlined in black correspond to individual measurements that were used to create the full map. These measurements are the highest-spatial-resolution observations ever made of Mercury's <span class="hlt">tail</span>. In less than six weeks, on October 6, 2008, similar measurements will be made during MESSENGER's second flyby of Mercury. Comparing the measurements from the two flybys will provide an unprecedented look at how Mercury's dynamic exosphere and <span class="hlt">tail</span> vary with time. Date Acquired: January 14, 2008. http://photojournal.jpl.nasa.gov/catalog/PIA11076</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003AGUFMSM22D..07K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003AGUFMSM22D..07K"><span>Magnetospheric Substorm Evolution in the Magnetotail: Challenge to Global MHD Modeling.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kuznetsova, M. M.; Hesse, M.; Dorelli, J.; Rastaetter, L.</p> <p>2003-12-01</p> <p>Testing the ability of global MHD models to describe magnetotail evolution during substroms is one of the elements of science based validation efforts at CCMC. We perform simulations of magnetotail dynamics using global MHD models residing at CCMC. We select solar wind conditions which drive the accumulation of magnetic field in the <span class="hlt">tail</span> lobes and subsequent magnetic reconnection and energy release. We will analyze the effects of spatial resolution in the plasma <span class="hlt">sheet</span> on modeled expansion phase evolution, maximum energy stored in the <span class="hlt">tail</span>, and details of magnetotail reconnection. We will pay special attention to <span class="hlt">current</span> <span class="hlt">sheet</span> thinning and multiple plasmoid formation.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_19 --> <div id="page_20" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="381"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016APS..DFDR13007H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016APS..DFDR13007H"><span>Ice <span class="hlt">sheets</span> on plastically-yielding beds</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hewitt, Ian</p> <p>2016-11-01</p> <p>Many fast flowing regions of ice <span class="hlt">sheets</span> are underlain by a layer of water-saturated sediments, or till. The rheology of the till has been the subject of some controversy, with laboratory tests suggesting almost perfectly plastic behaviour (stress independent of strain rate), but many models adopting a pseudo-viscous description. In this work, we consider the behaviour of glaciers underlain by a plastic bed. The ice is treated as a viscous gravity <span class="hlt">current</span>, on a bed that allows unconstrained slip above a critical yield stress. This simplified description allows rapid sliding, and aims to investigate 'worst-case' scenarios of possible ice-<span class="hlt">sheet</span> disintegration. The plastic bed results in an approximate ice-<span class="hlt">sheet</span> geometry that is primarily controlled by force balance, whilst ice velocity is determined from mass conservation (rather than the other way around, as standard models would hold). The stability of various states is considered, and particular attention is given to the pace at which transitions between unstable states can occur. Finally, we observe that the strength of basal tills depends strongly on pore pressure, and combine the model with a description of subglacial hydrology. Implications for the present-day ice <span class="hlt">sheets</span> in Greenland and Antarctica will be discussed. Funding: ERC Marie Curie FP7 Career Integration Grant.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.A33D0190B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.A33D0190B"><span>Characterization and Modeling of Dust Emissions from an Instrumented Mine <span class="hlt">Tailings</span> Site</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Betterton, E. A.; Stovern, M.; Saez, A.; Csavina, J. L.; Felix Villar, O. I.; Field, J. P.; Rine, K. P.; Russell, M. R.; Saliba, P.</p> <p>2012-12-01</p> <p>Mining operations are potential sources of airborne particulate metal and metalloid contaminants through both direct smelter emissions and wind erosion of mine <span class="hlt">tailings</span>. The warmer, drier conditions predicted for the Southwestern US by climate models may make contaminated atmospheric dust and aerosols increasingly important, due to potential deleterious effects on human health and ecology. Dust emissions and dispersion of contaminants from the Iron King Mine <span class="hlt">tailings</span> in Dewey-Humboldt, Arizona, a Superfund site, are <span class="hlt">currently</span> being investigated through in situ field measurements and computational fluid dynamics modeling. These <span class="hlt">tailings</span> are heavily contaminated with lead and arsenic. We report on the chemical characterization of atmospheric dust and aerosol sampled near the mine <span class="hlt">tailings</span>. Instrumented eddy flux towers were also setup on the mine <span class="hlt">tailings</span> to give both spatial and temporal dust observations. The eddy flux towers have multiple DUSTTRAK monitors as well as weather stations. These in situ observations allow us to assess spatial distribution of suspended particulate. Using the DUSTTRAK flux tower observations at 10-second resolution in conjunction with a computational fluid dynamics model, we have been able to model dust transport from the mine <span class="hlt">tailings</span> to downwind areas. In order to improve the accuracy of the dust transport simulations both regional topographical features and local weather patterns have been incorporated into the model simulations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005AGUFMSM21C..03C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005AGUFMSM21C..03C"><span>The Kelvin-Helmhotz instability and thin <span class="hlt">current</span> <span class="hlt">sheets</span> in the MHD and Hall MHD formalisms</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chacon, L.; Knoll, D.</p> <p>2005-12-01</p> <p>Sheared magnetic fields and sheared flows co-exist in many space, astrophysical, and laboratory plasmas. In such situations the evolution of the Kelvin-Helmhotz instability (KHI) can have a significant impact on the topology of the magnetic field. In particular, it can result in <span class="hlt">current</span> <span class="hlt">sheet</span> thinning [2,3], which may allow Hall scales to become relevant and result in fast reconnection rates [1]. There are a number of interesting applications of this phenomena in the magnetosphere. We will discuss some of our recent work in this area [1,2,3] with special focus on Hall MHD effects on the KHI [1]. As an example, we will discuss the parameter regime in which the 2-D parallel KHI can evolve for sub-Alfvenic flows [1]. This may have important implication for dayside reconnection in the magnetopause. [1] Chacon, Knoll, and Finn, Phys. Lett. A, vol. 308, 2003 [2] Knoll and Chacon, PRL, vol. 88, 2002 [3] Brackbill and Knoll, PRL, vol. 86, 2001</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015NatSR...5E9752E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015NatSR...5E9752E"><span><span class="hlt">Tail</span>-scope: Using friends to estimate heavy <span class="hlt">tails</span> of degree distributions in large-scale complex networks</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Eom, Young-Ho; Jo, Hang-Hyun</p> <p>2015-05-01</p> <p>Many complex networks in natural and social phenomena have often been characterized by heavy-<span class="hlt">tailed</span> degree distributions. However, due to rapidly growing size of network data and concerns on privacy issues about using these data, it becomes more difficult to analyze complete data sets. Thus, it is crucial to devise effective and efficient estimation methods for heavy <span class="hlt">tails</span> of degree distributions in large-scale networks only using local information of a small fraction of sampled nodes. Here we propose a <span class="hlt">tail</span>-scope method based on local observational bias of the friendship paradox. We show that the <span class="hlt">tail</span>-scope method outperforms the uniform node sampling for estimating heavy <span class="hlt">tails</span> of degree distributions, while the opposite tendency is observed in the range of small degrees. In order to take advantages of both sampling methods, we devise the hybrid method that successfully recovers the whole range of degree distributions. Our <span class="hlt">tail</span>-scope method shows how structural heterogeneities of large-scale complex networks can be used to effectively reveal the network structure only with limited local information.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20030020763','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20030020763"><span>Understanding Recent Mass Balance Changes of the Greenland Ice <span class="hlt">Sheet</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>vanderVeen, Cornelius</p> <p>2003-01-01</p> <p>The ultimate goal of this project is to better understand the <span class="hlt">current</span> transfer of mass between the Greenland Ice <span class="hlt">Sheet</span>, the world's oceans and the atmosphere, and to identify processes controlling the rate of this transfer, to be able to predict with greater confidence future contributions to global sea level rise. During the first year of this project, we focused on establishing longer-term records of change of selected outlet glaciers, reevaluation of mass input to the ice <span class="hlt">sheet</span> and analysis of climate records derived from ice cores, and modeling meltwater production and runoff from the margins of the ice <span class="hlt">sheet</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013EGUGA..15.8449B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013EGUGA..15.8449B"><span>Does climate have heavy <span class="hlt">tails</span>?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bermejo, Miguel; Mudelsee, Manfred</p> <p>2013-04-01</p> <p>When we speak about a distribution with heavy <span class="hlt">tails</span>, we are referring to the probability of the existence of extreme values will be relatively large. Several heavy-<span class="hlt">tail</span> models are constructed from Poisson processes, which are the most tractable models. Among such processes, one of the most important are the Lévy processes, which are those process with independent, stationary increments and stochastic continuity. If the random component of a climate process that generates the data exhibits a heavy-<span class="hlt">tail</span> distribution, and if that fact is ignored by assuming a finite-variance distribution, then there would be serious consequences (in the form, e.g., of bias) for the analysis of extreme values. Yet, it appears that it is an open question to what extent and degree climate data exhibit heavy-<span class="hlt">tail</span> phenomena. We present a study about the statistical inference in the presence of heavy-<span class="hlt">tail</span> distribution. In particular, we explore (1) the estimation of <span class="hlt">tail</span> index of the marginal distribution using several estimation techniques (e.g., Hill estimator, Pickands estimator) and (2) the power of hypothesis tests. The performance of the different methods are compared using artificial time-series by means of Monte Carlo experiments. We systematically apply the heavy <span class="hlt">tail</span> inference to observed climate data, in particular we focus on time series data. We study several proxy and directly observed climate variables from the instrumental period, the Holocene and the Pleistocene. This work receives financial support from the European Commission (Marie Curie Initial Training Network LINC, No. 289447, within the 7th Framework Programme).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFM.C11A0522M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFM.C11A0522M"><span>The Rapid Ice <span class="hlt">Sheet</span> Change Observatory (RISCO)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Morin, P.; Howat, I. M.; Ahn, Y.; Porter, C.; McFadden, E. M.</p> <p>2010-12-01</p> <p>The recent expansion of observational capacity from space has revealed dramatic, rapid changes in the Earth’s ice cover. These discoveries have fundamentally altered how scientists view ice-<span class="hlt">sheet</span> change. Instead of just slow changes in snow accumulation and melting over centuries or millennia, important changes can occur in sudden events lasting only months, weeks, or even a single day. Our understanding of these short time- and space-scale processes, which hold important implications for future global sea level rise, has been impeded by the low temporal and spatial resolution, delayed sensor tasking, incomplete coverage, inaccessibility and/or high cost of data available to investigators. New cross-agency partnerships and data access policies provide the opportunity to dramatically improve the resolution of ice <span class="hlt">sheet</span> observations by an order of magnitude, from timescales of months and distances of 10’s of meters, to days and meters or less. Advances in image processing technology also enable application of <span class="hlt">currently</span> under-utilized datasets. The infrastructure for systematically gathering, processing, analyzing and distributing these data does not <span class="hlt">currently</span> exist. Here we present the development of a multi-institutional, multi-platform observatory for rapid ice change with the ultimate objective of helping to elucidate the relevant timescales and processes of ice <span class="hlt">sheet</span> dynamics and response to climate change. The Rapid Ice <span class="hlt">Sheet</span> Observatory (RISCO) gathers observations of short time- and space-scale Cryosphere events and makes them easily accessible to investigators, media and general public. As opposed to existing data centers, which are structured to archive and distribute diverse types of raw data to end users with the specialized software and skills to analyze them, RISCO focuses on three types of geo-referenced raster (image) data products in a format immediately viewable with commonly available software. These three products are (1) sequences of images</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010ets..conf..245K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010ets..conf..245K"><span>The <span class="hlt">Tail</span> of BPM</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kruba, Steve; Meyer, Jim</p> <p></p> <p>Business process management suites (BPMS's) represent one of the fastest growing segments in the software industry as organizations automate their key business processes. As this market matures, it is interesting to compare it to Chris Anderson's 'Long <span class="hlt">Tail</span>.' Although the 2004 "Long <span class="hlt">Tail</span>" article in Wired magazine was primarily about the media and entertainment industries, it has since been applied (and perhaps misapplied) to other markets. Analysts describe a "<span class="hlt">Tail</span> of BPM" market that is, perhaps, several times larger than the traditional BPMS product market. This paper will draw comparisons between the concepts in Anderson's article (and subsequent book) and the BPM solutions market.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/15011778','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/15011778"><span>Detection of massive tidal <span class="hlt">tails</span> around the globular cluster Pal 5 with SDSS commissioning data</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Odenkirchen, Michael; Grebel, Eva K.; Rockosi, Constance M.</p> <p>2000-12-01</p> <p>We report the discovery of two well-defined tidal <span class="hlt">tails</span> emerging from the sparse remote globular cluster Palomar 5. These <span class="hlt">tails</span> stretch out symmetrically to both sides of the cluster in the direction of constant Galactic latitude and subtend an angle of 2.6{sup o} on the sky. The <span class="hlt">tails</span> have been detected in commissioning data of the Sloan Digital Sky Survey (SDSS), providing deep five-color photometry in a 2.5{sup o}-wide band along the equator. The stars in the <span class="hlt">tails</span> make up a substantial part ({approx} 1/3) of the <span class="hlt">current</span> total population of cluster stars in the magnitude interval 19.5 {le} i*more » {le} 22.0. This reveals that the cluster is subject to heavy mass loss. The orientation of the <span class="hlt">tails</span> provides an important key for the determination of the cluster's Galactic orbit.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AIPC.1567..800C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AIPC.1567..800C"><span>Numerical simulation for the magnetic force distribution in electromagnetic forming of small size flat <span class="hlt">sheet</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chen, Xiaowei; Wang, Wenping; Wan, Min</p> <p>2013-12-01</p> <p>It is essential to calculate magnetic force in the process of studying electromagnetic flat <span class="hlt">sheet</span> forming. Calculating magnetic force is the basis of analyzing the <span class="hlt">sheet</span> deformation and optimizing technical parameters. Magnetic force distribution on the <span class="hlt">sheet</span> can be obtained by numerical simulation of electromagnetic field. In contrast to other computing methods, the method of numerical simulation has some significant advantages, such as higher calculation accuracy, easier using and other advantages. In this paper, in order to study of magnetic force distribution on the small size flat <span class="hlt">sheet</span> in electromagnetic forming when flat round spiral coil, flat rectangular spiral coil and uniform pressure coil are adopted, the 3D finite element models are established by software ANSYS/EMAG. The magnetic force distribution on the <span class="hlt">sheet</span> are analyzed when the plane geometries of <span class="hlt">sheet</span> are equal or less than the coil geometries under fixed discharge impulse. The results showed that when the physical dimensions of <span class="hlt">sheet</span> are less than the corresponding dimensions of the coil, the variation of induced <span class="hlt">current</span> channel width on the <span class="hlt">sheet</span> will cause induced <span class="hlt">current</span> crowding effect that seriously influence the magnetic force distribution, and the degree of inhomogeneity of magnetic force distribution is increase nearly linearly with the variation of induced <span class="hlt">current</span> channel width; the small size uniform pressure coil will produce approximately uniform magnetic force distribution on the <span class="hlt">sheet</span>, but the coil is easy to early failure; the desirable magnetic force distribution can be achieved when the unilateral placed flat rectangular spiral coil is adopted, and this program can be take as preferred one, because the longevity of flat rectangular spiral coil is longer than the working life of small size uniform pressure coil.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JGRA..119.1827C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JGRA..119.1827C"><span>The quiet evening auroral arc and the structure of the growth phase near-Earth plasma <span class="hlt">sheet</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Coroniti, F. V.; Pritchett, P. L.</p> <p>2014-03-01</p> <p>The plasma pressure and <span class="hlt">current</span> configuration of the near-Earth plasma <span class="hlt">sheet</span> that creates and sustains the quiet evening auroral arc during the growth phase of magnetospheric substorms is investigated. We propose that the quiet evening arc (QEA) connects to the thin near-Earth <span class="hlt">current</span> <span class="hlt">sheet</span>, which forms during the development of the growth phase enhancement of convection. The <span class="hlt">current</span> <span class="hlt">sheet</span>'s large polarization electric fields are shielded from the ionosphere by an Inverted-V parallel potential drop, thereby producing the electron precipitation responsible for the arc's luminosity. The QEA is located in the plasma <span class="hlt">sheet</span> region of maximal radial pressure gradient and, in the east-west direction, follows the vanishing of the approximately dawn-dusk-directed gradient or fold in the plasma pressure. In the evening sector, the boundary between the Region1 and Region 2 <span class="hlt">current</span> systems occurs where the pressure maximizes (approximately radial gradient of the pressure vanishes) and where the approximately radial gradient of the magnetic flux tube volume also vanishes in an inflection region. The proposed intricate balance of plasma <span class="hlt">sheet</span> pressure and <span class="hlt">currents</span> may well be very sensitive to disruption by the arrival of equatorward traveling auroral streamers and their associated earthward traveling dipolarization fronts.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMSH11B4048S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMSH11B4048S"><span>Magnetic Reconnection in the Heliospheric <span class="hlt">Current</span> <span class="hlt">Sheet</span>: The Implications of the Different Environments Seen by the VoyagerSpacecraft</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Swisdak, M. M.; Drake, J. F.; Opher, M.</p> <p>2014-12-01</p> <p>The magnetic field abutting the heliospheric <span class="hlt">current</span> <span class="hlt">sheet</span> (HCS) is primarily in the azimuthal direction, either east-to-west or west-to-east. Mis-alignment of the solar rotational and magnetic axesleads to the characteristic ballerina-skirt shape of the HCS and during the solar cycle there can be large excursions in the <span class="hlt">sheet</span>'s latitudinal extent. Voyager 2's observations of energetic electrondropouts are related to its crossing of this boundary. Magnetic reconnection is also thought to occur as the HCS compresses and narrows between the termination shock and the heliopause. Near theequator the two HCS field alignments are present in roughly equal amounts, while near the edges the distribution can be considerably skewed. This will lead to substantial differences in the environmentsof the two Voyager spacecraft since Voyager 1 is north of the equator, but firmly in the sector region, while Voyager 2 is south of the equator and skirting the edges of the sector region. We presentparticle-in-cell simulations demonstrating the consequences of the reconnection of asymmetric amounts of flux. In particular, we will discuss Voyager 2's remaining time in the heliosphere -- including theimplications for the solar wind velocity, energetic particle transport, and the expected structure of Voyager 2's heliopause crossing -- and compare it with the data collected from Voyager 1.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2393739','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2393739"><span>Active <span class="hlt">tails</span> enhance arboreal acrobatics in geckos</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Jusufi, Ardian; Goldman, Daniel I.; Revzen, Shai; Full, Robert J.</p> <p>2008-01-01</p> <p>Geckos are nature's elite climbers. Their remarkable climbing feats have been attributed to specialized feet with hairy toes that uncurl and peel in milliseconds. Here, we report that the secret to the gecko's arboreal acrobatics includes an active <span class="hlt">tail</span>. We examine the <span class="hlt">tail</span>'s role during rapid climbing, aerial descent, and gliding. We show that a gecko's <span class="hlt">tail</span> functions as an emergency fifth leg to prevent falling during rapid climbing. A response initiated by slipping causes the <span class="hlt">tail</span> tip to push against the vertical surface, thereby preventing pitch-back of the head and upper body. When pitch-back cannot be prevented, geckos avoid falling by placing their <span class="hlt">tail</span> in a posture similar to a bicycle's kickstand. Should a gecko fall with its back to the ground, a swing of its <span class="hlt">tail</span> induces the most rapid, zero-angular momentum air-righting response yet measured. Once righted to a sprawled gliding posture, circular <span class="hlt">tail</span> movements control yaw and pitch as the gecko descends. Our results suggest that large, active <span class="hlt">tails</span> can function as effective control appendages. These results have provided biological inspiration for the design of an active <span class="hlt">tail</span> on a climbing robot, and we anticipate their use in small, unmanned gliding vehicles and multisegment spacecraft. PMID:18347344</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004APS..MARB23005H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004APS..MARB23005H"><span>Spinomotive force induced by a transverse displacement <span class="hlt">current</span> in a thin metal or doped-semiconductor <span class="hlt">sheet</span>: Classical and quantum views.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hu, Chia-Ren</p> <p>2004-03-01</p> <p>We present classical macroscopic, microscopic, and quantum mechanical arguments to show that in a metallic or electron/hole-doped semiconducting <span class="hlt">sheet</span> thinner than the screening length, a displacement <span class="hlt">current</span> applied normal to it can induce a spinomotive force along it. The magnitude is weak but clearly detectable. The classical arguments are purely electromagnetic. The quantum argument, based on the Dirac equation, shows that the predicted effect originates from the spin-orbit interaction, but not of the usual kind. That is, it relies on an external electric field, whereas the usual S-O interaction involves the electric field generated by the ions. Because the Dirac equation incorporatesThomas precession, which is due to relativistic kinematics, the quantum prediction is a factor of two smaller than the classical prediction. Replacing the displacement <span class="hlt">current</span> by a charge <span class="hlt">current</span>, and one obtains a new source for the spin-Hall effect. Classical macroscopic argument also predicts its existence, but the other two views are controversial.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22518602-turbulence-generated-proton-scale-structures-terrestrial-magnetosheath','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22518602-turbulence-generated-proton-scale-structures-terrestrial-magnetosheath"><span>TURBULENCE-GENERATED PROTON-SCALE STRUCTURES IN THE TERRESTRIAL MAGNETOSHEATH</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Vörös, Zoltán; Narita, Yasuhito; Yordanova, Emiliya</p> <p>2016-03-01</p> <p>Recent results of numerical magnetohydrodynamic simulations suggest that in collisionless space plasmas, turbulence can spontaneously generate thin <span class="hlt">current</span> <span class="hlt">sheets</span>. These coherent structures can partially explain the intermittency and the non-homogenous distribution of localized plasma heating in turbulence. In this Letter, Cluster multi-point observations are used to investigate the distribution of magnetic field discontinuities and the associated small-scale <span class="hlt">current</span> <span class="hlt">sheets</span> in the terrestrial magnetosheath downstream of a quasi-parallel bow shock. It is shown experimentally, for the first time, that the strongest turbulence-generated <span class="hlt">current</span> <span class="hlt">sheets</span> occupy the long <span class="hlt">tails</span> of probability distribution functions associated with extremal values of magnetic field partial derivatives.more » During the analyzed one-hour time interval, about a hundred strong discontinuities, possibly proton-scale <span class="hlt">current</span> <span class="hlt">sheets</span>, were observed.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.fs.usda.gov/treesearch/pubs/44112','TREESEARCH'); return false;" href="https://www.fs.usda.gov/treesearch/pubs/44112"><span>Survival rates of female white-<span class="hlt">tailed</span> deer on an industrial forest following a decline in population density</span></a></p> <p><a target="_blank" href="http://www.fs.usda.gov/treesearch/">Treesearch</a></p> <p>Shawn M. Crimmins; John W. Edwards; Patrick D. Keyser; James M. Crum; W. Mark Ford; Brad F. Miller; Tyler A. Campbell; Karl V. Miller</p> <p>2013-01-01</p> <p>With white-<span class="hlt">tailed</span> deer (Odocoileus virginianus) populations at historically high levels throughout many North American forests, many <span class="hlt">current</span> management activities are aimed at reducing deer populations. However, very little information exists on the ecology of low-density white-<span class="hlt">tailed</span> deer populations or populations that have declined in density. We...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25638082','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25638082"><span>Experimental investigation of a 1 kA/cm² <span class="hlt">sheet</span> beam plasma cathode electron gun.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kumar, Niraj; Pal, Udit Narayan; Pal, Dharmendra Kumar; Prajesh, Rahul; Prakash, Ram</p> <p>2015-01-01</p> <p>In this paper, a cold cathode based <span class="hlt">sheet</span>-beam plasma cathode electron gun is reported with achieved <span class="hlt">sheet</span>-beam <span class="hlt">current</span> density ∼1 kA/cm(2) from pseudospark based argon plasma for pulse length of ∼200 ns in a single shot experiment. For the qualitative assessment of the <span class="hlt">sheet</span>-beam, an arrangement of three isolated metallic-<span class="hlt">sheets</span> is proposed. The actual shape and size of the <span class="hlt">sheet</span>-electron-beam are obtained through a non-conventional method by proposing a dielectric charging technique and scanning electron microscope based imaging. As distinct from the earlier developed <span class="hlt">sheet</span> beam sources, the generated <span class="hlt">sheet</span>-beam has been propagated more than 190 mm distance in a drift space region maintaining <span class="hlt">sheet</span> structure without assistance of any external magnetic field.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4866485','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4866485"><span>Necrosis of the <span class="hlt">tail</span> of pancreas following proximal splenic artery embolization</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Talving, Peep; Rauk, Mariliis; Vipp, Liisa; Isand, Karl-Gunnar; Šamarin, Aleksandr; Põder, Kalle; Rätsep, Indrek; Saar, Sten</p> <p>2016-01-01</p> <p>The <span class="hlt">current</span> case report presents a rare complication of a significant pancreatic <span class="hlt">tail</span> necrosis following proximal splenic artery embolization in a 32-year-old male patient involved in a motorcycle accident. Proximal angiographic embolization of the splenic injury after trauma is a widely accepted method with excellent success rate; however, possible complications may occur and has been described in the literature. Nevertheless, only a few case reports pertinent to clinically significant pancreatic <span class="hlt">tail</span> necrosis after the SAE has been reported. Thus, we add a case report to the scarce literature pertinent to this detrimental and rare complication. PMID:27177891</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSH11B2436Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSH11B2436Y"><span>Numerical Study of the Cascading Energy Conversion of the Reconnecting <span class="hlt">Current</span> <span class="hlt">Sheet</span> in Solar Eruptions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ye, J.; Lin, J.; Raymond, J. C.; Shen, C.</p> <p>2017-12-01</p> <p>In this paper, we present a resistive magnetohydrodynamical study (2D) of the CME eruption based on the Lin & Forbes model (2000) regarding the cascading reconnection by a high-order Godunov scheme code, to better understand the physical mechanisms responsible for the internal structure of the <span class="hlt">current</span> <span class="hlt">sheet</span> (CS) and the high reconnection rate. The main improvements of this work include: 1) large enough spatial scale consistent with the stereo LASCO data that yields an observable <span class="hlt">current</span> <span class="hlt">sheet</span> 2) A realistic plasma environment (S&G, 1999) adopted rather than an isothermal atmosphere and higher resolution inside CS 3) The upper boundary condition set to be open. The simulation shows a typical acceleration below 2 R⊙, then its speed slightly fluctuated, and the flux rope velocity is estimated to be 100 km/s-250 km/s for a slow CME. The reconnection rates are around 0.02 estimated from inflow and outflow velocities. The dynamic features show a great consistence with the LASCO observations. Looking into the fine structure of CS, magnetic reconnection initializes with a Sweet-Parker stage, and undergoes the time-dependent Petschek/fractural patterns. While the CME continues climbing up, the outflow region becomes turbulent which enhances the reconnection rates furthermore. The local reconnection rates present a simple linear dependence with the length-width ratio of multiple small-scale CSs. The principal X-point is close to the Sun's surface during the entire eruption, causing the energy partition to be unequal. Energy conversion in the vicinity of the principal X-point has also been addressed by simply employing energy equations. And we demonstrate that the dominant energy transfer consists of a conversion of the incoming Poynting flux to enthalpy flux in the sunward direction and bulk kinetic energy in the CME direction. The spectrum of magnetic energy doesn't follow a simple power law after secondary islands appear, and the spectrum index varies from 1.5 to 2</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70035740','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70035740"><span>Comparison of the breeding biology of sympatric red-<span class="hlt">tailed</span> Hawks, White-<span class="hlt">tailed</span> Hawks, and Crested Caracaras in south Texas</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Actkinson, M.A.; Kuvlesky, W.P.; Boal, C.W.; Brennan, L.A.; Hernandez, F.</p> <p>2009-01-01</p> <p>We compared the breeding biology of sympatric nesting Red-<span class="hlt">tailed</span> Hawks (Buteo jamaicensis), White-<span class="hlt">tailed</span> Hawks (Buteo albicaudatus), and Crested Caracaras (Caracara cheriway) in south Texas during 2003 and 2004. We monitored 46 breeding attempts by Red-<span class="hlt">tailed</span> Hawks, 56 by White-<span class="hlt">tailed</span> Hawks, and 27 by Crested Caracaras. Observed nesting success was similar for Red-<span class="hlt">tailed</span> Hawks (62%) and Crested Caracaras (61%), but lower for White-<span class="hlt">tailed</span> Hawks (51%). Daily survival rates (0.99) were the same for all three species. Red-<span class="hlt">tailed</span> Hawks and White-<span class="hlt">tailed</span> Hawks both fledged 1.13 young per nesting pair and Crested Caracaras fledged 1.39 young per nesting pair. All three species nested earlier in 2004 than in 2003; in addition, the overall nesting density of these three species almost doubled from 2003 (1.45 pairs/km2) to 2004 (2.71 pairs/km2). Estimated productivity of all three species was within the ranges reported from other studies. Given extensive and progressive habitat alteration in some areas of south Texas, and the limited distributions of White-<span class="hlt">tailed</span> Hawks and Crested Caracaras, the presence of large ranches managed for free-range cattle production and hunting leases likely provides important habitat and may be key areas for conservation of these two species. ?? 2009 The Raptor Research Foundation, Inc.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_20 --> <div id="page_21" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="401"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29536120','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29536120"><span>Ecotoxicity of Mine <span class="hlt">Tailings</span>: Unrehabilitated Versus Rehabilitated.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Maboeta, M S; Oladipo, O G; Botha, S M</p> <p>2018-05-01</p> <p>Earthworms are bioindicators of soil pollution. The ecotoxicity of <span class="hlt">tailings</span> from selected gold mines in South Africa was investigated utilizing Eisenia andrei bioassays and biomarkers. Samples were obtained from unrehabilitated, rehabilitated and naturally vegetated sites. Biomass, neutral red retention time (NRRT), survival and reproduction were assessed using standardized protocols. Earthworm biomass, NRRT and reproductive success in rehabilitated <span class="hlt">tailings</span> (comparable to naturally vegetated site) were significantly higher (p < 0.05) than in unrehabilitated <span class="hlt">tailings</span>. In addition, significantly lower (p < 0.05) body tissue concentrations of As, Cd, Co, Cu and Ni contents were found in the rehabilitated <span class="hlt">tailings</span> compared to the unrehabilitated. Further, significantly lower (p < 0.05) soil Mn and Zn concentrations were obtained in unrehabilitated <span class="hlt">tailings</span> than the rehabilitated and naturally vegetated sites. Overall, reduced ecotoxicity effects were confirmed in rehabilitated compared to unrehabilitated <span class="hlt">tailings</span>. This suggests that rehabilitation as a post-mining restorative strategy has strong positive influence on mine <span class="hlt">tailings</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007AGUSMSM41A..06S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007AGUSMSM41A..06S"><span>Field-Aligned <span class="hlt">Current</span> at Plasma <span class="hlt">Sheet</span> Boundary Layers During Storm Time: Cluster Observation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Shi, J.; Cheng, Z.; Zhang, T.; Dunlop, M.; Liu, Z.</p> <p>2007-05-01</p> <p>The magnetic field data from the FGM instruments on board the four Cluster spacecrafts were used to study Field Aligned <span class="hlt">Current</span> (FAC) at the Plasma <span class="hlt">Sheet</span> Boundary Layers (PSBLs) with the so called "curlometer technique". We analyzed the date obtained in 2001 in the magnetotail and only two cases were found in the storm time. One (August 17, 2001) occurred from sudden commencement to main phase, and the other (October 1, 2001) lay in the main phase and recovery phase. The relationship between the FAC density and the AE index was studied and the results are shown as follows. (1) In the sudden commencement and the main phase the density of the FAC increases obviously, in the recovery phase the density of the FAC increases slightly. (2) From the sudden commencement to the initial stage of the main phase the FAC increases with decreasing AE index and decreases with increasing AE index. From the late stage of the main phase to initial stage of the recovery phase, the FAC increases with increasing AE index and decreases with decreasing AE index. In the late stage of the recovery phase the disturbance of the FAC is not so violent, so that the FAC varying with the AE index is not very obvious.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3968746','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3968746"><span>Microbially-accelerated consolidation of oil sands <span class="hlt">tailings</span>. Pathway I: changes in porewater chemistry</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Siddique, Tariq; Kuznetsov, Petr; Kuznetsova, Alsu; Arkell, Nicholas; Young, Rozlyn; Li, Carmen; Guigard, Selma; Underwood, Eleisha; Foght, Julia M.</p> <p>2014-01-01</p> <p>Dispersed clay particles in mine <span class="hlt">tailings</span> and soft sediments remain suspended for decades, hindering consolidation and challenging effective management of these aqueous slurries. <span class="hlt">Current</span> geotechnical engineering models of self-weight consolidation of <span class="hlt">tailings</span> do not consider microbial contribution to sediment behavior, however, here we show that microorganisms indigenous to oil sands <span class="hlt">tailings</span> change the porewater chemistry and accelerate consolidation of oil sands <span class="hlt">tailings</span>. A companion paper describes the role of microbes in alteration of clay chemistry in <span class="hlt">tailings</span>. Microbial metabolism in mature fine <span class="hlt">tailings</span> (MFT) amended with an organic substrate (hydrolyzed canola meal) produced methane (CH4) and carbon dioxide (CO2). Dissolution of biogenic CO2 lowered the pH of amended MFT to pH 6.4 vs. unamended MFT (pH 7.7). About 12% more porewater was recovered from amended than unamended MFT during 2 months of active microbial metabolism, concomitant with consolidation of <span class="hlt">tailings</span>. The lower pH in amended MFT dissolved carbonate minerals, thereby releasing divalent cations including calcium (Ca2+) and magnesium (Mg2+) and increasing bicarbonate (HCO−3) in porewater. The higher concentrations increased the ionic strength of the porewater, in turn reducing the thickness of the diffuse double layer (DDL) of clay particles by reducing the surface charge potential (repulsive forces) of the clay particles. The combination of these processes accelerated consolidation of oil sands <span class="hlt">tailings</span>. In addition, ebullition of biogenic gases created transient physical channels for release of porewater. In contrast, saturating the MFT with non-biogenic CO2 had little effect on consolidation. These results have significant implications for management and reclamation of oil sands <span class="hlt">tailings</span> ponds and broad importance in anaerobic environments such as contaminated harbors and estuaries containing soft sediments rich in clays and organics. PMID:24711805</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24711805','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24711805"><span>Microbially-accelerated consolidation of oil sands <span class="hlt">tailings</span>. Pathway I: changes in porewater chemistry.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Siddique, Tariq; Kuznetsov, Petr; Kuznetsova, Alsu; Arkell, Nicholas; Young, Rozlyn; Li, Carmen; Guigard, Selma; Underwood, Eleisha; Foght, Julia M</p> <p>2014-01-01</p> <p>Dispersed clay particles in mine <span class="hlt">tailings</span> and soft sediments remain suspended for decades, hindering consolidation and challenging effective management of these aqueous slurries. <span class="hlt">Current</span> geotechnical engineering models of self-weight consolidation of <span class="hlt">tailings</span> do not consider microbial contribution to sediment behavior, however, here we show that microorganisms indigenous to oil sands <span class="hlt">tailings</span> change the porewater chemistry and accelerate consolidation of oil sands <span class="hlt">tailings</span>. A companion paper describes the role of microbes in alteration of clay chemistry in <span class="hlt">tailings</span>. Microbial metabolism in mature fine <span class="hlt">tailings</span> (MFT) amended with an organic substrate (hydrolyzed canola meal) produced methane (CH4) and carbon dioxide (CO2). Dissolution of biogenic CO2 lowered the pH of amended MFT to pH 6.4 vs. unamended MFT (pH 7.7). About 12% more porewater was recovered from amended than unamended MFT during 2 months of active microbial metabolism, concomitant with consolidation of <span class="hlt">tailings</span>. The lower pH in amended MFT dissolved carbonate minerals, thereby releasing divalent cations including calcium (Ca(2+)) and magnesium (Mg(2+)) and increasing bicarbonate (HCO(-) 3) in porewater. The higher concentrations increased the ionic strength of the porewater, in turn reducing the thickness of the diffuse double layer (DDL) of clay particles by reducing the surface charge potential (repulsive forces) of the clay particles. The combination of these processes accelerated consolidation of oil sands <span class="hlt">tailings</span>. In addition, ebullition of biogenic gases created transient physical channels for release of porewater. In contrast, saturating the MFT with non-biogenic CO2 had little effect on consolidation. These results have significant implications for management and reclamation of oil sands <span class="hlt">tailings</span> ponds and broad importance in anaerobic environments such as contaminated harbors and estuaries containing soft sediments rich in clays and organics.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://files.eric.ed.gov/fulltext/ED232618.pdf','ERIC'); return false;" href="http://files.eric.ed.gov/fulltext/ED232618.pdf"><span>Videotex 1983. An ERIC Fact <span class="hlt">Sheet</span>.</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Olson, Michael</p> <p></p> <p>The capabilities and potential of videotex, a two-way interactive communication and information retrieval service, are briefly described in this fact <span class="hlt">sheet</span>. Videotex refers to a two-way linkage between databases and individual consumers in home or office. It is <span class="hlt">currently</span> being used for information retrieval, transactions (e.g., bill paying,…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1989JSP....57..675W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1989JSP....57..675W"><span>Long-time <span class="hlt">tails</span> of the green-kubo integrands for a binary mixture</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wood, W. W.</p> <p>1989-11-01</p> <p>The long-time <span class="hlt">tails</span> for the mutual diffusion coefficient, the thermal diffusivity, the thermal conductivity, and the shear and longitudinal viscosities (from which the <span class="hlt">tail</span> of the bulk viscosity can be calculated) of a nonreactive binary mixture are calculated from mode-coupling theory, and compared with a prior calculation by Pomeau. Three different choices of the thermal forces and <span class="hlt">currents</span> are considered, with the results found to take their simplest form in the case of the de Groot "double-primed set". The decompositions into the kinetic, potential, and cross terms are given.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1998APS..DPP.K6S06S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1998APS..DPP.K6S06S"><span>Space Charge Effect in the <span class="hlt">Sheet</span> and Solid Electron Beam</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Song, Ho Young; Kim, Hyoung Suk; Ahn, Saeyoung</p> <p>1998-11-01</p> <p>We analyze the space charge effect of two different types of electron beam ; <span class="hlt">sheet</span> and solid electron beam. Electron gun simulations are carried out using shadow and control grids for high and low perveance. Rectangular and cylindrical geometries are used for <span class="hlt">sheet</span> and solid electron beam in planar and disk type cathode. The E-gun code is used to study the limiting <span class="hlt">current</span> and space charge loading in each geometries.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19850059791&hterms=FAC&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DFAC','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19850059791&hterms=FAC&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DFAC"><span>ISEE-1 and 2 observations of field-aligned <span class="hlt">currents</span> in the distant midnight magnetosphere</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Elphic, R. C.; Kelly, T. J.; Russell, C. T.</p> <p>1985-01-01</p> <p>Magnetic field measurements obtained in the nightside magnetosphere by the co-orbiting ISEE-1 and 2 spacecraft have been examined for signatures of field-aligned <span class="hlt">currents</span> (FAC). Such <span class="hlt">currents</span> are found on the boundary of the plasma <span class="hlt">sheet</span> both when the plasma <span class="hlt">sheet</span> is expanding and when it is thinning. Evidence is often found for the existence of waves on the plasma <span class="hlt">sheet</span> boundary, leading to multiple crossings of the FAC <span class="hlt">sheet</span>. At times the boundary layer FAC <span class="hlt">sheet</span> orientation is nearly parallel to the X-Z GSM plane, suggesting 'protrusions' of plasma <span class="hlt">sheet</span> into the lobes. The boundary layer <span class="hlt">current</span> polarity is, as expected, into the ionosphere in the midnight to dawn local time sector, and outward near dusk. <span class="hlt">Current</span> <span class="hlt">sheet</span> thicknesses and velocities are essentially independent of plasma <span class="hlt">sheet</span> expansion or thinning, having typical values of 1500 km and 20-40 km/s respectively. Characteristic boundary layer <span class="hlt">current</span> densities are about 10 nanoamps per square meter.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19980231998','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19980231998"><span>Effect of <span class="hlt">Tail</span> Dihedral on Lateral Control Effectiveness at High Subsonic Speeds of Differentially Deflected Horizontal-<span class="hlt">Tail</span> Surfaces on a Configuration having a Thin Highly Tapered Wing</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Fournier, Paul G.</p> <p>1959-01-01</p> <p>Tests have been conducted in the Langley high-speed 7- by 10-foot tunnel to determine the effect of <span class="hlt">tail</span> dihedral on lateral control effectiveness of a complete-model configuration having differentially deflected horizontal-<span class="hlt">tail</span> surfaces. Limited tests were made to determine the lateral characteristics as well as the longitudinal characteristics in sideslip. The wing had an aspect ratio of 3, a taper ratio of 0.14, 28.80 deg sweep of the quarter-chord line with zero sweep at the 80-percent-chord line, and NACA 65A004 airfoil sections. The test Mach number range extended from 0.60 to 0.92. There are only small variations in the roll effectiveness parameter C(sub iota delta) with negative <span class="hlt">tail</span> dihedral angle. The <span class="hlt">tail</span> size used on the test model, however, is perhaps inadequate for providing the roll rates specified by <span class="hlt">current</span> military requirements at subsonic speeds. The lateral aerodynamic characteristics were essentially constant throughout the range of sideslip angle from 12 deg to -12 deg. A general increase in yawing moment was noted with increased negative dihedral throughout the Mach number range.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA492729','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA492729"><span>Active <span class="hlt">Tails</span> Enhance Arboreal Acrobatics in Geckos</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>2008-03-18</p> <p>the secret to the gecko s arboreal acrobatics includes an active <span class="hlt">tail</span>. We examine the <span class="hlt">tail</span> s role during rapid climbing, aerial descent, and gliding. We show that a gecko s <span class="hlt">tail</span> functions as an emergency fifth leg to prevent falling during rapid climbing. A response initiated by slipping causes the <span class="hlt">tail</span> tip to push against the vertical surface, thereby preventing pitch-back of the head and upper body. When pitch-back cannot be prevented, geckos avoid falling by placing their <span class="hlt">tail</span> in a posture similar to a bicycle s kickstand. Should a gecko fall with its back to the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27129422','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27129422"><span>A cis-prenyltransferase from Methanosarcina acetivorans catalyzes both head-to-<span class="hlt">tail</span> and nonhead-to-<span class="hlt">tail</span> prenyl condensation.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ogawa, Takuya; Emi, Koh-Ichi; Koga, Kazushi; Yoshimura, Tohru; Hemmi, Hisashi</p> <p>2016-06-01</p> <p>Cis-prenyltransferase usually consecutively catalyzes the head-to-<span class="hlt">tail</span> condensation reactions of isopentenyl diphosphate to allylic prenyl diphosphate in the production of (E,Z-mixed) polyprenyl diphosphate, which is the precursor of glycosyl carrier lipids. Some recently discovered homologs of the enzyme, however, catalyze the nonhead-to-<span class="hlt">tail</span> condensation reactions between allylic prenyl diphosphates. In this study, we characterize a cis-prenyltransferase homolog from a methanogenic archaeon, Methanosarcina acetivorans, to obtain information on the biosynthesis of the glycosyl carrier lipids within it. This enzyme catalyzes both head-to-<span class="hlt">tail</span> and nonhead-to-<span class="hlt">tail</span> condensation reactions. The kinetic analysis shows that the main reaction of the enzyme is consecutive head-to-<span class="hlt">tail</span> prenyl condensation reactions yielding polyprenyl diphosphates, while the chain lengths of the major products seem shorter than expected for the precursor of glycosyl carrier lipids. On the other hand, a subsidiary reaction of the enzyme, i.e., nonhead-to-<span class="hlt">tail</span> condensation between dimethylallyl diphosphate and farnesyl diphosphate, gives a novel diterpenoid compound, geranyllavandulyl diphosphate. © 2016 Federation of European Biochemical Societies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20150007710','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20150007710"><span>The Substorm <span class="hlt">Current</span> Wedge: Further Insights from MHD Simulations</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Birn, J.; Hesse, M.</p> <p>2015-01-01</p> <p>Using a recent magnetohydrodynamic simulation of magnetotail dynamics, we further investigate the buildup and evolution of the substorm <span class="hlt">current</span> wedge (SCW), resulting from flow bursts generated by near-<span class="hlt">tail</span> reconnection. Each flow burst generates an individual <span class="hlt">current</span> wedge, which includes the reduction of cross-<span class="hlt">tail</span> <span class="hlt">current</span> and the diversion to region 1 (R1)-type field-aligned <span class="hlt">currents</span> (earthward on the dawn and tailward on the duskside), connecting the <span class="hlt">tail</span> with the ionosphere. Multiple flow bursts generate initially multiple SCW patterns, which at later times combine to a wider single SCW pattern. The standard SCWmodel is modified by the addition of several <span class="hlt">current</span> loops, related to particular magnetic field changes: the increase of Bz in a local equatorial region (dipolarization), the decrease of |Bx| away from the equator (<span class="hlt">current</span> disruption), and increases in |By| resulting from azimuthally deflected flows. The associated loop <span class="hlt">currents</span> are found to be of similar magnitude, 0.1-0.3 MA. The combined effect requires the addition of region 2 (R2)-type <span class="hlt">currents</span> closing in the near <span class="hlt">tail</span> through dawnward <span class="hlt">currents</span> but also connecting radially with the R1 <span class="hlt">currents</span>. The <span class="hlt">current</span> closure at the inner boundary, taken as a crude proxy of an idealized ionosphere, demonstrates westward <span class="hlt">currents</span> as postulated in the original SCW picture as well as North-South <span class="hlt">currents</span> connecting R1- and R2-type <span class="hlt">currents</span>, which were larger than the westward <span class="hlt">currents</span> by a factor of almost 2. However, this result should be applied with caution to the ionosphere because of our neglect of finite resistance and Hall effects.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28191715','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28191715"><span>A Two-<span class="hlt">Tailed</span> Phosphopeptide Crystallizes to Form a Lamellar Structure.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Pellach, Michal; Mondal, Sudipta; Harlos, Karl; Mance, Deni; Baldus, Marc; Gazit, Ehud; Shimon, Linda J W</p> <p>2017-03-13</p> <p>The crystal structure of a designed phospholipid-inspired amphiphilic phosphopeptide at 0.8 Å resolution is presented. The phosphorylated β-hairpin peptide crystallizes to form a lamellar structure that is stabilized by intra- and intermolecular hydrogen bonding, including an extended β-<span class="hlt">sheet</span> structure, as well as aromatic interactions. This first reported crystal structure of a two-<span class="hlt">tailed</span> peptidic bilayer reveals similarities in thickness to a typical phospholipid bilayer. However, water molecules interact with the phosphopeptide in the hydrophilic region of the lattice. Additionally, solid-state NMR was used to demonstrate correlation between the crystal structure and supramolecular nanostructures. The phosphopeptide was shown to self-assemble into semi-elliptical nanosheets, and solid-state NMR provides insight into the self-assembly mechanisms. This work brings a new dimension to the structural study of biomimetic amphiphilic peptides with determination of molecular organization at the atomic level. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23739423','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23739423"><span>Ice-<span class="hlt">sheet</span> mass balance and climate change.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hanna, Edward; Navarro, Francisco J; Pattyn, Frank; Domingues, Catia M; Fettweis, Xavier; Ivins, Erik R; Nicholls, Robert J; Ritz, Catherine; Smith, Ben; Tulaczyk, Slawek; Whitehouse, Pippa L; Zwally, H Jay</p> <p>2013-06-06</p> <p>Since the 2007 Intergovernmental Panel on Climate Change Fourth Assessment Report, new observations of ice-<span class="hlt">sheet</span> mass balance and improved computer simulations of ice-<span class="hlt">sheet</span> response to continuing climate change have been published. Whereas Greenland is losing ice mass at an increasing pace, <span class="hlt">current</span> Antarctic ice loss is likely to be less than some recently published estimates. It remains unclear whether East Antarctica has been gaining or losing ice mass over the past 20 years, and uncertainties in ice-mass change for West Antarctica and the Antarctic Peninsula remain large. We discuss the past six years of progress and examine the key problems that remain.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017NPGeo..24..737M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017NPGeo..24..737M"><span>Optimal heavy <span class="hlt">tail</span> estimation - Part 1: Order selection</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mudelsee, Manfred; Bermejo, Miguel A.</p> <p>2017-12-01</p> <p>The <span class="hlt">tail</span> probability, P, of the distribution of a variable is important for risk analysis of extremes. Many variables in complex geophysical systems show heavy <span class="hlt">tails</span>, where P decreases with the value, x, of a variable as a power law with a characteristic exponent, α. Accurate estimation of α on the basis of data is <span class="hlt">currently</span> hindered by the problem of the selection of the order, that is, the number of largest x values to utilize for the estimation. This paper presents a new, widely applicable, data-adaptive order selector, which is based on computer simulations and brute force search. It is the first in a set of papers on optimal heavy <span class="hlt">tail</span> estimation. The new selector outperforms competitors in a Monte Carlo experiment, where simulated data are generated from stable distributions and AR(1) serial dependence. We calculate error bars for the estimated α by means of simulations. We illustrate the method on an artificial time series. We apply it to an observed, hydrological time series from the River Elbe and find an estimated characteristic exponent of 1.48 ± 0.13. This result indicates finite mean but infinite variance of the statistical distribution of river runoff.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26887494','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26887494"><span>Ice stream activity scaled to ice <span class="hlt">sheet</span> volume during Laurentide Ice <span class="hlt">Sheet</span> deglaciation.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Stokes, C R; Margold, M; Clark, C D; Tarasov, L</p> <p>2016-02-18</p> <p>The contribution of the Greenland and West Antarctic ice <span class="hlt">sheets</span> to sea level has increased in recent decades, largely owing to the thinning and retreat of outlet glaciers and ice streams. This dynamic loss is a serious concern, with some modelling studies suggesting that the collapse of a major ice <span class="hlt">sheet</span> could be imminent or potentially underway in West Antarctica, but others predicting a more limited response. A major problem is that observations used to initialize and calibrate models typically span only a few decades, and, at the ice-<span class="hlt">sheet</span> scale, it is unclear how the entire drainage network of ice streams evolves over longer timescales. This represents one of the largest sources of uncertainty when predicting the contributions of ice <span class="hlt">sheets</span> to sea-level rise. A key question is whether ice streams might increase and sustain rates of mass loss over centuries or millennia, beyond those expected for a given ocean-climate forcing. Here we reconstruct the activity of 117 ice streams that operated at various times during deglaciation of the Laurentide Ice <span class="hlt">Sheet</span> (from about 22,000 to 7,000 years ago) and show that as they activated and deactivated in different locations, their overall number decreased, they occupied a progressively smaller percentage of the ice <span class="hlt">sheet</span> perimeter and their total discharge decreased. The underlying geology and topography clearly influenced ice stream activity, but--at the ice-<span class="hlt">sheet</span> scale--their drainage network adjusted and was linked to changes in ice <span class="hlt">sheet</span> volume. It is unclear whether these findings can be directly translated to modern ice <span class="hlt">sheets</span>. However, contrary to the view that sees ice streams as unstable entities that can accelerate ice-<span class="hlt">sheet</span> deglaciation, we conclude that ice streams exerted progressively less influence on ice <span class="hlt">sheet</span> mass balance during the retreat of the Laurentide Ice <span class="hlt">Sheet</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.C23C..03S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.C23C..03S"><span>Surface water hydrology and the Greenland Ice <span class="hlt">Sheet</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Smith, L. C.; Yang, K.; Pitcher, L. H.; Overstreet, B. T.; Chu, V. W.; Rennermalm, A. K.; Cooper, M. G.; Gleason, C. J.; Ryan, J.; Hubbard, A.; Tedesco, M.; Behar, A.</p> <p>2016-12-01</p> <p>Mass loss from the Greenland Ice <span class="hlt">Sheet</span> now exceeds 260 Gt/year, raising global sea level by >0.7 mm annually. Approximately two-thirds of this total mass loss is now driven by negative ice <span class="hlt">sheet</span> surface mass balance (SMB), attributed mainly to production and runoff of meltwater from the ice <span class="hlt">sheet</span> surface. This new dominance of runoff as a driver of GrIS total mass loss will likely persist owing to anticipated further increases in surface melting, reduced meltwater storage in firn, and the waning importance of dynamical mass losses (ice calving) as the ice <span class="hlt">sheets</span> retreat from their marine-terminating margins. It also creates the need and opportunity for integrative research pairing traditional surface water hydrology approaches with glaciology. As one example, we present a way to measure supraglacial "runoff" (i.e. specific discharge) at the supraglacial catchment scale ( 101-102 km2), using in situ measurements of supraglacial river discharge and high-resolution satellite/drone mapping of upstream catchment area. This approach, which is standard in terrestrial hydrology but novel for ice <span class="hlt">sheet</span> science, enables independent verification and improvement of modeled SMB runoff estimates used to project sea level rise. Furthermore, because <span class="hlt">current</span> SMB models do not consider the role of fluvial watershed processes operating on the ice surface, inclusion of even a simple surface routing model materially improves simulations of runoff delivered to moulins, the critical pathways for meltwater entry into the ice <span class="hlt">sheet</span>. Incorporating principles of surface water hydrology and fluvial geomorphology and into glaciological models will thus aid estimates of Greenland meltwater runoff to the global ocean as well as connections to subglacial hydrology and ice <span class="hlt">sheet</span> dynamics.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20080007493&hterms=correlated+anti-correlated&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dcorrelated%2Banti-correlated','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20080007493&hterms=correlated+anti-correlated&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dcorrelated%2Banti-correlated"><span>Slow Mode Waves in the Heliospheric Plasma <span class="hlt">Sheet</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Smith, Edward. J.; Zhou, Xiaoyan</p> <p>2007-01-01</p> <p>We report the results of a search for waves/turbulence in the Heliospheric Plasma <span class="hlt">Sheet</span> (HPS) surrounding the Heliospheric <span class="hlt">Current</span> <span class="hlt">Sheet</span> (HCS). The HPS is treated as a distinctive heliospheric structure distinguished by relatively high Beta, slow speed plasma. The data used in the investigation are from a previously published study of the thicknesses of the HPS and HCS that were obtained in January to May 2004 when Ulysses was near aphelion at 5 AU. The advantage of using these data is that the HPS is thicker at large radial distances and the spacecraft spends longer intervals inside the plasma <span class="hlt">sheet</span>. From the study of the magnetic field and solar wind velocity components, we conclude that, if Alfven waves are present, they are weak and are dominated by variations in the field magnitude, B, and solar wind density, NP, that are anti-correlated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70014240','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70014240"><span>Ecological aspects of microorganisms inhabiting uranium mill <span class="hlt">tailings</span></span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Miller, C.L.; Landa, E.R.; Updegraff, D.M.</p> <p>1987-01-01</p> <p>Numbers and types of microorganisms in uranium mill <span class="hlt">tailings</span> were determined using culturing techniques. Arthrobacter were found to be the predominant microorganism inhabiting the sandy <span class="hlt">tailings</span>, whereas Bacillus and fungi predominated in the slime <span class="hlt">tailings</span>. Sulfate-reducing bacteria, capable of leaching radium, were isolated in low numbers from <span class="hlt">tailings</span> samples but were isolated in significantly high numbers from topsoil in contact with the <span class="hlt">tailings</span>. The results are placed in the context of the magnitude of uranium mill <span class="hlt">tailings</span> in the United States, the hazards posed by the <span class="hlt">tailings</span>, and how such hazards could be enhanced or diminished by microbial activities. Patterns in the composition of the microbial population are evaluated with respect to the ecological variables that influence microbial growth. ?? 1987 Springer-Verlag New York Inc.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19750020523','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19750020523"><span>The source of the electric field in the nightside magnetosphere</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Stern, D. P.</p> <p>1975-01-01</p> <p>In the open magnetosphere model magnetic field lines from the polar caps connect to the interplanetary magnetic field and conduct an electric field from interplanetary space to the polar ionosphere. By examining the magnetic flux involved it is concluded that only slightly more than half of the magnetic flux in the polar caps belongs to open field lines and that such field lines enter or leave the magnetosphere through narrow elongated windows stretching the <span class="hlt">tail</span>. These window regions are identified with the <span class="hlt">tail</span>'s boundary region and shift their position with changes in the interplanetary magnetic field, in particular when a change of interplanetary magnetic sector occurs. The circuit providing electric <span class="hlt">current</span> in the magnetopause and the plasma <span class="hlt">sheet</span> is extended across those windows; thus energy is drained from the interplanetary electric field and an electric potential drop is produced across the plasma <span class="hlt">sheet</span>. The polar cap receives its electric field from interplanetary space on the day side from open magnetic field lines and on the night side from closed field lines leading to the plasma <span class="hlt">sheet</span>. The theory described provides improved understanding of magnetic flux bookkeeping, of the origin of Birkeland <span class="hlt">currents</span>, and of the boundary layer of the geomagnetic <span class="hlt">tail</span>.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_21 --> <div id="page_22" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="421"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JMEP...25.3506J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JMEP...25.3506J"><span>Metallurgical Effects of Shunting <span class="hlt">Current</span> on Resistance Spot-Welded Joints of AA2219 <span class="hlt">Sheets</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jafari Vardanjani, M.; Araee, A.; Senkara, J.; Jakubowski, J.; Godek, J.</p> <p>2016-08-01</p> <p>Shunting effect is the loss of electrical <span class="hlt">current</span> via the secondary circuit provided due to the existence of previous nugget in a series of welding spots. This phenomenon influences on metallurgical aspects of resistance spot-welded (RSW) joints in terms of quality and performance. In this paper RSW joints of AA2219 <span class="hlt">sheets</span> with 1 mm thickness are investigated metallurgically for shunted and single spots. An electro-thermal finite element analysis is performed on the RSW process of shunted spot and temperature distribution and variation are obtained. These predictions are then compared with experimental micrographs. Three values of 5 mm, 20 mm, and infinite (i.e., single spot) are assumed for welding distance. Numerical and experimental results are matching each other in terms of nugget and HAZ geometry as increasing distance raised nugget size and symmetry of HAZ. In addition, important effect of shunting <span class="hlt">current</span> on nugget thickness, microstructure, and Copper segregation on HAZ grain boundaries were discovered. A quantitative analysis is also performed about the influence of welding distance on important properties including ratio of nugget thickness and diameter ( r t), ratio of HAZ area on shunted and free side of nugget ( r HA), and ratio of equivalent segregated and total amount of Copper, measured in sample ( r Cu) on HAZ. Increasing distance from 5 mm to infinite, indicated a gain of 111.04, -45.55, and -75.15% in r t, r HA, and r Cu, respectively, while obtained ratios for 20 mm welding distance was suitable compared to single spot.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19830066648&hterms=earth+magnetic+field&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dearth%2Bmagnetic%2Bfield','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19830066648&hterms=earth+magnetic+field&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dearth%2Bmagnetic%2Bfield"><span>Average configuration of the distant (less than 220-earth-radii) magnetotail - Initial ISEE-3 magnetic field results</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Slavin, J. A.; Tsurutani, B. T.; Smith, E. J.; Jones, D. E.; Sibeck, D. G.</p> <p>1983-01-01</p> <p>Magnetic field measurements from the first two passes of the ISEE-3 GEOTAIL Mission have been used to study the structure of the trans-lunar <span class="hlt">tail</span>. Good agreement was found between the ISEE-3 magnetopause crossings and the Explorer 33, 35 model of Howe and Binsack (1972). Neutral <span class="hlt">sheet</span> location was well ordered by the hinged <span class="hlt">current</span> <span class="hlt">sheet</span> models based upon near earth measurements. Between X = -20 and -120 earth radii the radius of the <span class="hlt">tail</span> increases by about 30 percent while the lobe field strength decreases by approximately 60 percent. Beyond X = -100 to -1200 earth radii the <span class="hlt">tail</span> diameter and lobe field magnitude become nearly constant at terminal values of approximately 60 earth radii and 9 nT, respectively. The distance at which the <span class="hlt">tail</span> was observed to cease flaring, 100-120 earth radii, is in close agreement with the predictions of the analytic <span class="hlt">tail</span> model of Coroniti and Kennel (1972). Overall, the findings of this study suggest that the magnetotail retains much of its near earth structure out to X = -220 earth radii.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19930036996&hterms=magnetic+particles&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dmagnetic%2Bparticles','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19930036996&hterms=magnetic+particles&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dmagnetic%2Bparticles"><span>Initial signatures of magnetic field and energetic particle fluxes at <span class="hlt">tail</span> reconfiguration - Explosive growth phase</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Ohtani, S.; Takahashi, K.; Zanetti, L. J.; Potemra, T. A.; Mcentire, R. W.; Iijima, T.</p> <p>1992-01-01</p> <p>The initial signatures of <span class="hlt">tail</span> field reconfiguration observed in the near-earth magnetotail are examined using data obtained by the AMPTE/CCE magnetometer and the Medium Energy Particle Analyzer. It is found that the <span class="hlt">tail</span> reconfiguration events could be classified as belonging to two types, Type I and Type II. In Type I events, a <span class="hlt">current</span> disruption is immersed in a hot plasma region expanding from inward (earthward/equatorward) of the spacecraft; consequently, the spacecraft is immersed in a hot plasma region expanding from inward. The Type II reconfiguration event is characterized by a distinctive interval (explosive growth phase) just prior to the local commencement of <span class="hlt">tail</span> phase.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19720026264','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19720026264"><span>An elastic analysis of stresses in a uniaxially loaded <span class="hlt">sheet</span> containing an interference-fit bolt</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Crews, J. H., Jr.</p> <p>1972-01-01</p> <p>The stresses in a <span class="hlt">sheet</span> with an interference-fit bolt have been calculated for two <span class="hlt">sheet</span>-bolt interface conditions: a frictionless interface and a fixed (no-slip) interface. The stress distributions were calculated for various combinations of <span class="hlt">sheet</span> and bolt moduli. The results show that for repeated loading the local stress range is significantly smaller if an interference bolt is used instead of a loosely fitting one. This reduction in local stress range is more pronounced when the ratio of bolt modulus to <span class="hlt">sheet</span> modulus is large. The analysis also indicates that <span class="hlt">currently</span> used standard values of interference cause yielding in the <span class="hlt">sheet</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.loc.gov/pictures/collection/hh/item/ca1230.photos.011800p/','SCIGOV-HHH'); return false;" href="https://www.loc.gov/pictures/collection/hh/item/ca1230.photos.011800p/"><span>71. PALMDALE WATER COMPANY, EASTWOOD MULTIPLEARCHED DAM: STRESS <span class="hlt">SHEET</span>, <span class="hlt">SHEET</span> ...</span></a></p> <p><a target="_blank" href="http://www.loc.gov/pictures/collection/hh/">Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey</a></p> <p></p> <p></p> <p>71. PALMDALE WATER COMPANY, EASTWOOD MULTIPLE-ARCHED DAM: STRESS <span class="hlt">SHEET</span>, <span class="hlt">SHEET</span> 3; DECEMBER 20, 1918. Littlerock Water District files. - Little Rock Creek Dam, Little Rock Creek, Littlerock, Los Angeles County, CA</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/980650-ray-crystal-structure-phage-tail-terminator-protein-reveals-biologically-relevant-hexameric-rang-structure-demonstrates-conserved-mechanism-tail-termination-among-divrse-long-tailed-phages','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/980650-ray-crystal-structure-phage-tail-terminator-protein-reveals-biologically-relevant-hexameric-rang-structure-demonstrates-conserved-mechanism-tail-termination-among-divrse-long-tailed-phages"><span>The X-ray Crystal Structure of the Phage <span class="hlt">Tail</span> Terminator Protein Reveals the Biologically Relevant Hexameric Rang Structure and Demonstrates a Conserved mechanism of <span class="hlt">Tail</span> Termination among Divrse Long <span class="hlt">Tailed</span> Phages</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Pell, L.; Liu, A; Edmonds, L</p> <p></p> <p>The <span class="hlt">tail</span> terminator protein (TrP) plays an essential role in phage <span class="hlt">tail</span> assembly by capping the rapidly polymerizing <span class="hlt">tail</span> once it has reached its requisite length and serving as the interaction surface for phage heads. Here, we present the 2.7-A crystal structure of a hexameric ring of gpU, the TrP of phage ?. Using sequence alignment analysis and site-directed mutagenesis, we have shown that this multimeric structure is biologically relevant and we have delineated its functional surfaces. Comparison of the hexameric crystal structure with the solution structure of gpU that we previously solved using NMR spectroscopy shows large structural changesmore » occurring upon multimerization and suggests a mechanism that allows gpU to remain monomeric at high concentrations on its own, yet polymerize readily upon contact with an assembled <span class="hlt">tail</span> tube. The gpU hexamer displays several flexible loops that play key roles in head and <span class="hlt">tail</span> binding, implying a role for disorder-to-order transitions in controlling assembly as has been observed with other ? morphogenetic proteins. Finally, we have found that the hexameric structure of gpU is very similar to the structure of a putative TrP from a contractile phage <span class="hlt">tail</span> even though it displays no detectable sequence similarity. This finding coupled with further bioinformatic investigations has led us to conclude that the TrPs of non-contractile-<span class="hlt">tailed</span> phages, such as ?, are evolutionarily related to those of contractile-<span class="hlt">tailed</span> phages, such as P2 and Mu, and that all long-<span class="hlt">tailed</span> phages may utilize a conserved mechanism for <span class="hlt">tail</span> termination.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005APS..DPPCP1106F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005APS..DPPCP1106F"><span>Fine scale structure in the <span class="hlt">current</span> <span class="hlt">sheet</span> and electrostatic fields during driven magnetic reconnection on the VTF experiment.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fox, William</p> <p>2005-10-01</p> <p>We have conducted a series of experiments in the VTF reconnection experiment[1] to measure with high resolution the <span class="hlt">current</span> channel and electric structures that form in response to driven reconnection. Preliminary measurements have revealed that the <span class="hlt">current</span> <span class="hlt">sheet</span> is not symmetric across the X-line, contradicting an assumption fundamental to nearly every reconnection theory. Importantly, effects related to this asymmetry can account for momentum balance for the electrons at the X-line (i.e. fulfillment of the generalized Ohm's law) via convective inertia (m n v.∇v||). Measurements of strong in-plane electric field structures (E˜ 1 kV/m) near the X-point reveal a mechanism to efficiently heat ions, as has been recently observed by laser induced fluorescence (LIF) measurements of the ion distribution function[2].This work was supported by a DoE Fusion Energy Sciences Fellowship.[1] J. Egedal, et. al. (2001), Rev. Sci. Instrum. 71, 3351 [2] A. Stark, W. Fox, J.Egedal, O. Grulke, T. Klinger, (2005), submitted to Phys. Rev. Lett.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20100021385&hterms=Plasma+Ring&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DPlasma%2BRing','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20100021385&hterms=Plasma+Ring&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DPlasma%2BRing"><span>Recent Simulation Results on Ring <span class="hlt">Current</span> Dynamics Using the Comprehensive Ring <span class="hlt">Current</span> Model</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Zheng, Yihua; Zaharia, Sorin G.; Lui, Anthony T. Y.; Fok, Mei-Ching</p> <p>2010-01-01</p> <p>Plasma <span class="hlt">sheet</span> conditions and electromagnetic field configurations are both crucial in determining ring <span class="hlt">current</span> evolution and connection to the ionosphere. In this presentation, we investigate how different conditions of plasma <span class="hlt">sheet</span> distribution affect ring <span class="hlt">current</span> properties. Results include comparative studies in 1) varying the radial distance of the plasma <span class="hlt">sheet</span> boundary; 2) varying local time distribution of the source population; 3) varying the source spectra. Our results show that a source located farther away leads to a stronger ring <span class="hlt">current</span> than a source that is closer to the Earth. Local time distribution of the source plays an important role in determining both the radial and azimuthal (local time) location of the ring <span class="hlt">current</span> peak pressure. We found that post-midnight source locations generally lead to a stronger ring <span class="hlt">current</span>. This finding is in agreement with Lavraud et al.. However, our results do not exhibit any simple dependence of the local time distribution of the peak ring <span class="hlt">current</span> (within the lower energy range) on the local time distribution of the source, as suggested by Lavraud et al. [2008]. In addition, we will show how different specifications of the magnetic field in the simulation domain affect ring <span class="hlt">current</span> dynamics in reference to the 20 November 2007 storm, which include initial results on coupling the CRCM with a three-dimensional (3-D) plasma force balance code to achieve self-consistency in the magnetic field.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013ERL.....8a5017R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013ERL.....8a5017R"><span>Understanding Greenland ice <span class="hlt">sheet</span> hydrology using an integrated multi-scale approach</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rennermalm, A. K.; Moustafa, S. E.; Mioduszewski, J.; Chu, V. W.; Forster, R. R.; Hagedorn, B.; Harper, J. T.; Mote, T. L.; Robinson, D. A.; Shuman, C. A.; Smith, L. C.; Tedesco, M.</p> <p>2013-03-01</p> <p>Improved understanding of Greenland ice <span class="hlt">sheet</span> hydrology is critically important for assessing its impact on <span class="hlt">current</span> and future ice <span class="hlt">sheet</span> dynamics and global sea level rise. This has motivated the collection and integration of in situ observations, model development, and remote sensing efforts to quantify meltwater production, as well as its phase changes, transport, and export. Particularly urgent is a better understanding of albedo feedbacks leading to enhanced surface melt, potential positive feedbacks between ice <span class="hlt">sheet</span> hydrology and dynamics, and meltwater retention in firn. These processes are not isolated, but must be understood as part of a continuum of processes within an integrated system. This letter describes a systems approach to the study of Greenland ice <span class="hlt">sheet</span> hydrology, emphasizing component interconnections and feedbacks, and highlighting research and observational needs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015ApPhL.106u3503M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015ApPhL.106u3503M"><span>Large-<span class="hlt">current</span>-controllable carbon nanotube field-effect transistor in electrolyte solution</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Myodo, Miho; Inaba, Masafumi; Ohara, Kazuyoshi; Kato, Ryogo; Kobayashi, Mikinori; Hirano, Yu; Suzuki, Kazuma; Kawarada, Hiroshi</p> <p>2015-05-01</p> <p>Large-<span class="hlt">current</span>-controllable carbon nanotube field-effect transistors (CNT-FETs) were fabricated with mm-long CNT <span class="hlt">sheets</span>. The <span class="hlt">sheets</span>, synthesized by remote-plasma-enhanced CVD, contained both single- and double-walled CNTs. Titanium was deposited on the <span class="hlt">sheet</span> as source and drain electrodes, and an electrolyte solution was used as a gate electrode (solution gate) to apply a gate voltage to the CNTs through electric double layers formed around the CNTs. The drain <span class="hlt">current</span> came to be well modulated as electrolyte solution penetrated into the <span class="hlt">sheets</span>, and one of the solution gate CNT-FETs was able to control a large <span class="hlt">current</span> of over 2.5 A. In addition, we determined the transconductance parameter per tube and compared it with values for other CNT-FETs. The potential of CNT <span class="hlt">sheets</span> for applications requiring the control of large <span class="hlt">current</span> is exhibited in this study.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.C11E..01K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.C11E..01K"><span>Extensive Holocene ice <span class="hlt">sheet</span> grounding line retreat and uplift-driven readvance in West Antarctica</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kingslake, J.; Scherer, R. P.; Albrecht, T.; Coenen, J. J.; Powell, R. D.; Reese, R.; Stansell, N.; Tulaczyk, S. M.; Whitehouse, P. L.</p> <p>2017-12-01</p> <p>The West Antarctic Ice <span class="hlt">Sheet</span> (WAIS) reached its Last Glacial Maximum (LGM) extent 29-14 kyr before present. Numerical models used to project future ice-<span class="hlt">sheet</span> contributions to sea-level rise exploit reconstructions of post-LGM ice mass loss to tune model parameterizations. Ice-<span class="hlt">sheet</span> reconstructions are poorly constrained in areas where floating ice shelves or a lack of exposed geology obstruct conventional glacial-geological techniques. In the Weddell and Ross Sea sectors, ice-<span class="hlt">sheet</span> reconstructions have traditionally assumed progressive grounding line (GL) retreat throughout the Holocene. Contrasting this view, using three distinct lines of evidence, we show that the GL retreated hundreds of kilometers inland of its present position, before glacial isostatic rebound during the Mid to Late Holocene caused the GL to readvance to its <span class="hlt">current</span> position. Evidence for retreat and readvance during the last glacial termination includes (1) widespread radiocarbon in sediment cores recovered from beneath ice streams along the Siple and Gould Coasts, indicating marine exposure at least 200 km inland of the <span class="hlt">current</span> GL, (2) ice-penetrating radar observations of relic crevasses and other englacial structures preserved in slow-moving grounded ice, indicating ice-shelf grounding and (3) an ensemble of new ice-<span class="hlt">sheet</span> simulations showing widespread post-LGM retreat of the GL inland of its <span class="hlt">current</span> location and later readvance. The model indicates that GL readvance across low slope ice-stream troughs requires uplift-driven grounding of the ice shelf on topographic highs (ice rises). Our findings highlight ice-shelf pinning points and lithospheric response to unloading as drivers of major ice-<span class="hlt">sheet</span> fluctuations. Full WAIS collapse likely requires GL retreat well beyond its <span class="hlt">current</span> position in the Ronne and Ross Sectors and linkage via Amundsen Sea sector glaciers.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19810023062','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19810023062"><span>Ice <span class="hlt">sheet</span> altimetry</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Brooks, R. L.</p> <p>1981-01-01</p> <p>Generalized surface slopes were computed for the Antarctic and Greenland ice <span class="hlt">sheets</span> by differencing plotted contour levels and dividing them by the distance between the contours. It was observed that more than 90% of the ice <span class="hlt">sheets</span> have surface slopes less than 1%. Seasat test mode-1 Seasat altimeter measurements over Greenland were analyzed by comparisons with collinear and intersecting normal mode Seasat altimeter passes. Over the ice <span class="hlt">sheet</span>, the computed surface elevations from test mode-1 measurements were consistently lower by about 45 m and the AGC levels were down by approximately 6 dB. No test mode-1 data were acquired over Antarctica. It is concluded that analysis of the existing altimeter data base over the two ice <span class="hlt">sheets</span> is crucial in designing a future improved altimeter tracking capability. It is recommended that additional waveform retracking be performed to characterize ice <span class="hlt">sheet</span> topography as a function of geographic area and elevation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017APS..DPPGO4008E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017APS..DPPGO4008E"><span>Coherent <span class="hlt">current</span>-carrying filaments during nonlinear reconnecting ELMs and VDEs</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ebrahimi, Fatima</p> <p>2017-10-01</p> <p>We have examined plasmoid-mediated reconnection in a spherical tokamak using global nonlinear three-dimensional resistive MHD simulations with NIMROD. We have shown that physical <span class="hlt">current</span> <span class="hlt">sheets</span>/layers develop near the edge as a peeling component of ELMs or during vertical displacement events (associated with the scrape-off layer <span class="hlt">currents</span> - halo <span class="hlt">currents</span>), can become unstable to nonaxisymmetric 3-D <span class="hlt">current-sheet</span> instabilities (peeling- or tearing-like) and nonlinearly form edge coherent <span class="hlt">current</span>-carrying filaments. Time-evolving edge <span class="hlt">current</span> <span class="hlt">sheets</span> with reconnecting nature in NSTX and NSTX-U configurations are identified. In the case of peeling-like edge localized modes, the longstanding problem of quasiperiodic ELMs cycles is explained through the relaxation of edge <span class="hlt">current</span> via direct numerical calculations of reconnecting emf terms. For the VDEs during disruption, we show that as the plasma is vertically displaced, edge halo <span class="hlt">current</span> <span class="hlt">sheet</span> becomes MHD unstable and forms coherent edge <span class="hlt">current</span> filament structures, which would eventually bleed into the walls. Our model explains some essential asymmetric physics relevant to the experimental observations. Supported by DOE Grants DE-SC0010565, DE-AC02-09CH11466.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.loc.gov/pictures/collection/hh/item/nj0254.photos.110293p/','SCIGOV-HHH'); return false;" href="https://www.loc.gov/pictures/collection/hh/item/nj0254.photos.110293p/"><span>5. Historic American Buildings Survey Taken from drawing <span class="hlt">sheet</span>, <span class="hlt">SHEET</span> ...</span></a></p> <p><a target="_blank" href="http://www.loc.gov/pictures/collection/hh/">Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey</a></p> <p></p> <p></p> <p>5. Historic American Buildings Survey Taken from drawing <span class="hlt">sheet</span>, <span class="hlt">SHEET</span> #21, Showing the house as restored since Survey. (Dormer windows omitted as not authentic) - Samuel des Marest House, River Road, New Milford, Bergen County, NJ</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27468041','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27468041"><span>EAR AND <span class="hlt">TAIL</span> LESIONS ON CAPTIVE WHITE-<span class="hlt">TAILED</span> DEER FAWNS (ODOCOILEUS VIRGINIANUS): A CASE STUDY.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ferguson, Treena L; Demarais, Stephen; Cooley, Jim; Fleming, Sherrill; Michel, Eric S; Flinn, Emily</p> <p>2016-06-01</p> <p>During the 2008-2011 time period, undiagnosed lesions were observed in 21 of 150 white-<span class="hlt">tailed</span> deer fawns (Odocoileus virginianus) that were part of a captive deer herd at Mississippi State University. Clinical findings in healthy and diseased fawns from 0 to 90 days of age included bite and scratch marks followed by moderate to severe ear and <span class="hlt">tail</span> necrosis. Gross necropsy findings of necrotizing ulcerative dermatitis correlated with histopathologic findings that included focally severe multifocal vasculitis, vascular necrosis, and thrombosis. This article is a clinical description of these previously unreported lesions associated with tissue necrosis in young captive white-<span class="hlt">tailed</span> deer.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19780013752','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19780013752"><span>On the average configuration of the geomagnetic <span class="hlt">tail</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Fairfield, D. H.</p> <p>1978-01-01</p> <p>Over 3000 hours of IMP-6 magnetic field data obtained between 20 and 33 R sub E in the geomagnetic <span class="hlt">tail</span> have been used in a statistical study of the <span class="hlt">tail</span> configuration. A distribution of 2.5 minute averages of B sub Z as a function of position across the <span class="hlt">tail</span> reveals that more flux crosses the equatorial plane near the dawn and dusk flanks than near midnight. The <span class="hlt">tail</span> field projected in the solar magnetospheric equatorial plane deviates from the X axis due to flaring and solar wind aberration by an angle alpha = -0.9 y sub SM - 1.7 where Y sub SM is in earth radii and alpha is in degrees. After removing these effects the Y component of the <span class="hlt">tail</span> field is found to depend on interplanetary sector structure. During an away sector the B sub Y component of the <span class="hlt">tail</span> field is on average 0.5 gamma greater than that during a toward sector, a result that is true in both <span class="hlt">tail</span> lobes and is independent of location across the <span class="hlt">tail</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005AGUFMED33A1235S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005AGUFMED33A1235S"><span>RICO Graduate Student Research Flight: The Island <span class="hlt">Tail</span> Objective</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Small, J. D.; Anderson-Bereznicki, S. D.; Medeiros, B.; Nuijens, L.; Henry, C. K.; O'Donnell, D. M.; Morales, F.; Shen, H.</p> <p>2005-12-01</p> <p>The Rain in Cumulus over the Ocean (RICO) project was an intensive field project aimed to study and understand precipitation processes in trade wind cumulus. The project took place from Nov 23, 2004 until Jan 25, 2005 on two small islands of the Lesser Antilles, Antigua and Barbuda, where trade wind cumulus fields frequently occur during suppressed wintertime conditions. RICO provided a unique combination of research and education by offering the RICO Graduate Seminar Series and the development and implementation of a graduate student designed and directed research flight. One of the main goals of the graduate student research flight was to allow graduate students to participate in the process of developing a research flight plan and identifying scientific goals and objectives first-hand. Added benefits included the possibility of addressing scientific questions not included in the main RICO objectives. This also involved collaboration when discussing different ideas and initiatives and the full development of all stages of the research flight including the coordination of two research aircraft (NCAR-C130, University of Wyoming King Air), one research vessel (RV Seward Johnson), S-Pol radar site and real time operations center satellite information. Seventeen graduate students from both the US and Europe developed two different plans to be presented to RICO project principle investigators; both of which were approved. The island <span class="hlt">tail</span> objective aimed at characterizing the line of clouds known as 'island <span class="hlt">tails</span>' that frequently form off the leeward coast of the Caribbean islands. This objective was successful in its implementation on Jan 18, 2005 with measurements made in vigorous, waterspout producing <span class="hlt">tail</span> clouds immediately downwind of Barbuda. The investigation of these '<span class="hlt">tails</span>' fills a void in <span class="hlt">current</span> cloud physics research since it is the first time this ubiquitous feature of trade-wind islands has been the focus of careful study. Scientific questions to be</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22392313-experimental-investigation-ka-cm-sup-sheet-beam-plasma-cathode-electron-gun','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22392313-experimental-investigation-ka-cm-sup-sheet-beam-plasma-cathode-electron-gun"><span>Experimental investigation of a 1 kA/cm{sup 2} <span class="hlt">sheet</span> beam plasma cathode electron gun</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Kumar, Niraj, E-mail: niraj.ceeri@gmail.com; Narayan Pal, Udit; Prajesh, Rahul</p> <p></p> <p>In this paper, a cold cathode based <span class="hlt">sheet</span>-beam plasma cathode electron gun is reported with achieved <span class="hlt">sheet</span>-beam <span class="hlt">current</span> density ∼1 kA/cm{sup 2} from pseudospark based argon plasma for pulse length of ∼200 ns in a single shot experiment. For the qualitative assessment of the <span class="hlt">sheet</span>-beam, an arrangement of three isolated metallic-<span class="hlt">sheets</span> is proposed. The actual shape and size of the <span class="hlt">sheet</span>-electron-beam are obtained through a non-conventional method by proposing a dielectric charging technique and scanning electron microscope based imaging. As distinct from the earlier developed <span class="hlt">sheet</span> beam sources, the generated <span class="hlt">sheet</span>-beam has been propagated more than 190 mm distance inmore » a drift space region maintaining <span class="hlt">sheet</span> structure without assistance of any external magnetic field.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24552963','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24552963"><span>Modeling the emission, transport and deposition of contaminated dust from a mine <span class="hlt">tailing</span> site.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Stovern, Michael; Betterton, Eric A; Sáez, A Eduardo; Villar, Omar Ignacio Felix; Rine, Kyle P; Russell, Mackenzie R; King, Matt</p> <p>2014-01-01</p> <p>Mining operations are potential sources of airborne particulate metal and metalloid contaminants through both direct smelter emissions and wind erosion of mine <span class="hlt">tailings</span>. The warmer, drier conditions predicted for the Southwestern US by climate models may make contaminated atmospheric dust and aerosols increasingly important, due to potential deleterious effects on human health and ecology. Dust emissions and dispersion of contaminants from the Iron King Mine <span class="hlt">tailings</span> in Dewey-Humboldt, Arizona, a Superfund site, are <span class="hlt">currently</span> being investigated through in situ field measurements and computational fluid dynamics modeling. These <span class="hlt">tailings</span> are significantly contaminated with lead and arsenic with an average soil concentration of 1616 and 1420 ppm, respectively. Similar levels of these contaminants have also been measured in soil samples taken from the area surrounding the mine <span class="hlt">tailings</span>. Using a computational fluid dynamics model, we have been able to model dust transport from the mine <span class="hlt">tailings</span> to the surrounding region. The model includes a distributed Eulerian model to simulate fine aerosol transport and a Lagrangian approach to model fate and transport of larger particles. In order to improve the accuracy of the dust transport simulations both regional topographical features and local weather patterns have been incorporated into the model simulations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AIPC.1896t0010R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AIPC.1896t0010R"><span>Development of a low energy micro <span class="hlt">sheet</span> forming machine</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Razali, A. R.; Ann, C. T.; Shariff, H. M.; Kasim, N. I.; Musa, M. A.; Ahmad, A. F.</p> <p>2017-10-01</p> <p>It is expected that with the miniaturization of materials being processed, energy consumption is also being `miniaturized' proportionally. The focus of this study was to design a low energy micro-<span class="hlt">sheet</span>-forming machine for thin <span class="hlt">sheet</span> metal application and fabricate a low direct <span class="hlt">current</span> powered micro-<span class="hlt">sheet</span>-forming machine. A prototype of low energy system for a micro-<span class="hlt">sheet</span>-forming machine which includes mechanical and electronic elements was developed. The machine was tested for its performance in terms of natural frequency, punching forces, punching speed and capability, energy consumption (single punch and frequency-time based). Based on the experiments, the machine can do 600 stroke per minute and the process is unaffected by the machine's natural frequency. It was also found that sub-Joule of power was required for a single stroke of punching/blanking process. Up to 100micron thick carbon steel shim was successfully tested and punched. It concludes that low power forming machine is feasible to be developed and be used to replace high powered machineries to form micro-products/parts.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_22 --> <div id="page_23" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="441"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018JaJAP..57fHC04T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018JaJAP..57fHC04T"><span>Numerical analysis of band <span class="hlt">tails</span> in nanowires and their effects on the performance of tunneling field-effect transistors</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tanaka, Takahisa; Uchida, Ken</p> <p>2018-06-01</p> <p>Band <span class="hlt">tails</span> in heavily doped semiconductors are one of the important parameters that determine transfer characteristics of tunneling field-effect transistors. In this study, doping concentration and doing profile dependences of band <span class="hlt">tails</span> in heavily doped Si nanowires were analyzed by a nonequilibrium Green function method. From the calculated band <span class="hlt">tails</span>, transfer characteristics of nanowire tunnel field-effect transistors were numerically analyzed by Wentzel–Kramer–Brillouin approximation with exponential barriers. The calculated transfer characteristics demonstrate that the band <span class="hlt">tails</span> induced by dopants degrade the subthreshold slopes of Si nanowires from 5 to 56 mV/dec in the worst case. On the other hand, surface doping leads to a high drain <span class="hlt">current</span> while maintaining a small subthreshold slope.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27656335','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27656335"><span>Modular model for Mercury's magnetospheric magnetic field confined within the average observed magnetopause.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Korth, Haje; Tsyganenko, Nikolai A; Johnson, Catherine L; Philpott, Lydia C; Anderson, Brian J; Al Asad, Manar M; Solomon, Sean C; McNutt, Ralph L</p> <p>2015-06-01</p> <p>Accurate knowledge of Mercury's magnetospheric magnetic field is required to understand the sources of the planet's internal field. We present the first model of Mercury's magnetospheric magnetic field confined within a magnetopause shape derived from Magnetometer observations by the MErcury Surface, Space ENvironment, GEochemistry, and Ranging spacecraft. The field of internal origin is approximated by a dipole of magnitude 190 nT R M 3 , where R M is Mercury's radius, offset northward by 479 km along the spin axis. External field sources include <span class="hlt">currents</span> flowing on the magnetopause boundary and in the cross-<span class="hlt">tail</span> <span class="hlt">current</span> <span class="hlt">sheet</span>. The cross-<span class="hlt">tail</span> <span class="hlt">current</span> is described by a disk-shaped <span class="hlt">current</span> near the planet and a <span class="hlt">sheet</span> <span class="hlt">current</span> at larger (≳ 5 R M ) antisunward distances. The <span class="hlt">tail</span> <span class="hlt">currents</span> are constrained by minimizing the root-mean-square (RMS) residual between the model and the magnetic field observed within the magnetosphere. The magnetopause <span class="hlt">current</span> contributions are derived by shielding the field of each module external to the magnetopause by minimizing the RMS normal component of the magnetic field at the magnetopause. The new model yields improvements over the previously developed paraboloid model in regions that are close to the magnetopause and the nightside magnetic equatorial plane. Magnetic field residuals remain that are distributed systematically over large areas and vary monotonically with magnetic activity. Further advances in empirical descriptions of Mercury's magnetospheric external field will need to account for the dependence of the <span class="hlt">tail</span> and magnetopause <span class="hlt">currents</span> on magnetic activity and additional sources within the magnetosphere associated with Birkeland <span class="hlt">currents</span> and plasma distributions near the dayside magnetopause.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5014231','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5014231"><span>Modular model for Mercury's magnetospheric magnetic field confined within the average observed magnetopause</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Tsyganenko, Nikolai A.; Johnson, Catherine L.; Philpott, Lydia C.; Anderson, Brian J.; Al Asad, Manar M.; Solomon, Sean C.; McNutt, Ralph L.</p> <p>2015-01-01</p> <p>Abstract Accurate knowledge of Mercury's magnetospheric magnetic field is required to understand the sources of the planet's internal field. We present the first model of Mercury's magnetospheric magnetic field confined within a magnetopause shape derived from Magnetometer observations by the MErcury Surface, Space ENvironment, GEochemistry, and Ranging spacecraft. The field of internal origin is approximated by a dipole of magnitude 190 nT RM 3, where RM is Mercury's radius, offset northward by 479 km along the spin axis. External field sources include <span class="hlt">currents</span> flowing on the magnetopause boundary and in the cross‐<span class="hlt">tail</span> <span class="hlt">current</span> <span class="hlt">sheet</span>. The cross‐<span class="hlt">tail</span> <span class="hlt">current</span> is described by a disk‐shaped <span class="hlt">current</span> near the planet and a <span class="hlt">sheet</span> <span class="hlt">current</span> at larger (≳ 5 RM) antisunward distances. The <span class="hlt">tail</span> <span class="hlt">currents</span> are constrained by minimizing the root‐mean‐square (RMS) residual between the model and the magnetic field observed within the magnetosphere. The magnetopause <span class="hlt">current</span> contributions are derived by shielding the field of each module external to the magnetopause by minimizing the RMS normal component of the magnetic field at the magnetopause. The new model yields improvements over the previously developed paraboloid model in regions that are close to the magnetopause and the nightside magnetic equatorial plane. Magnetic field residuals remain that are distributed systematically over large areas and vary monotonically with magnetic activity. Further advances in empirical descriptions of Mercury's magnetospheric external field will need to account for the dependence of the <span class="hlt">tail</span> and magnetopause <span class="hlt">currents</span> on magnetic activity and additional sources within the magnetosphere associated with Birkeland <span class="hlt">currents</span> and plasma distributions near the dayside magnetopause. PMID:27656335</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1914075A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1914075A"><span>Non-thermal electron distribution functions through 3D magnetic reconnection instabilities in the solar wind</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Alejandro Munoz Sepulveda, Patricio; Buechner, Joerg</p> <p>2017-04-01</p> <p>The effects of kinetic instabilities on the solar wind electron velocity distribution functions (eVDFs) are mostly well understood under local homogeneous and stationary conditions. But the solar wind also contains <span class="hlt">current</span> <span class="hlt">sheets</span>, which affect the local properties of instabilities, turbulence and thus the observed non-maxwellian features in the eVDFs. Those processes are vastly unexplored. Therefore, we aim to investigate the influence of self-consistently generated turbulence via electron-scale instabilities in reconnecting <span class="hlt">current</span> <span class="hlt">sheets</span> on the formation of suprathermal features in the eVDFs. For this sake, we carry out 3D fully-kinetic Particle-in-Cell code numerical simulations of force free <span class="hlt">current</span> <span class="hlt">sheets</span> with a guide magnetic field. We find extended <span class="hlt">tails</span>, anisotropic plateaus and non-gyrotropic features in the eVDFs, correlated with the locations and time where micro-turbulence is enhanced in the <span class="hlt">current</span> <span class="hlt">sheet</span> due to <span class="hlt">current</span>-aligned streaming instabilities. We also discuss the influence of the plasma parameters, such as the ion to electron temperature ratio, on the excitation of <span class="hlt">current</span> <span class="hlt">sheet</span> instabilities and their effect on the properties of the eVDFs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017MsT.........14S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017MsT.........14S"><span><span class="hlt">Tail</span> Shape Design of Boat Wind Turbines</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Singamsitty, Venkatesh</p> <p></p> <p>Wind energy is a standout among the most generally utilized sustainable power source assets. A great deal of research and improvements have been happening in the wind energy field. Wind turbines are mechanical devices that convert kinetic energy into electrical power. Boat wind turbines are for the small-scale generation of electric power. In order to catch wind energy effectively, boat wind turbines need to face wind direction. <span class="hlt">Tails</span> are used in boat wind turbines to alter the wind turbine direction and receive the variation of the incoming direction of wind. <span class="hlt">Tails</span> are used to change the performance of boat wind turbines in an effective way. They are required to generate a quick and steady response as per change in wind direction. <span class="hlt">Tails</span> can have various shapes, and their effects on boat wind turbines are different. However, the effects of <span class="hlt">tail</span> shapes on the performance of boat wind turbines are not thoroughly studied yet. In this thesis, five <span class="hlt">tail</span> shapes were studied. Their effects on boat wind turbines were investigated. The power extracted by the turbines from the air and the force acting on the boat wind turbine <span class="hlt">tail</span> were analyzed. The results of this thesis provide a guideline of <span class="hlt">tail</span> shape design for boat wind turbines.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19910020835','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19910020835"><span>F/A-18 1/9th scale model <span class="hlt">tail</span> buffet measurements</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Martin, C. A.; Glaister, M. K.; Maclaren, L. D.; Meyn, L. A.; Ross, J.</p> <p>1991-01-01</p> <p>Wind tunnel tests were carried out on a 1/9th scale model of the F/A-18 at high angles of attack to investigate the characteristics of <span class="hlt">tail</span> buffet due to bursting of the wing leading edge extension (LEX) vortices. The tests were carried out at the Aeronautical Research Laboratory low-speed wind tunnel facility and form part of a collaborative activity with NASA Ames Research Center, organized by The Technical Cooperative Program (TTCP). Information from the program will be used in the planning of similar collaborative tests, to be carried out at NASA Ames, on a full-scale aircraft. The program covered the measurement of unsteady pressures and fin vibration for cases with and without the wing LEX fences fitted. Fourier transform methods were used to analyze the unsteady data, and information on the spatial and temporal content of the vortex burst pressure field was obtained. Flow visualization of the vortex behavior was carried out using smoke and a laser light <span class="hlt">sheet</span> technique.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5004610','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5004610"><span>Quasi-steady state aerodynamics of the cheetah <span class="hlt">tail</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Boje, Edward; Fisher, Callen; Louis, Leeann; Lane, Emily</p> <p>2016-01-01</p> <p>ABSTRACT During high-speed pursuit of prey, the cheetah (Acinonyx jubatus) has been observed to swing its <span class="hlt">tail</span> while manoeuvring (e.g. turning or braking) but the effect of these complex motions is not well understood. This study demonstrates the potential of the cheetah's long, furry <span class="hlt">tail</span> to impart torques and forces on the body as a result of aerodynamic effects, in addition to the well-known inertial effects. The first-order aerodynamic forces on the <span class="hlt">tail</span> are quantified through wind tunnel testing and it is observed that the fur nearly doubles the effective frontal area of the <span class="hlt">tail</span> without much mass penalty. Simple dynamic models provide insight into manoeuvrability via simulation of pitch, roll and yaw <span class="hlt">tail</span> motion primitives. The inertial and quasi-steady state aerodynamic effects of <span class="hlt">tail</span> actuation are quantified and compared by calculating the angular impulse imparted onto the cheetah's body and its shown aerodynamic effects contribute to the <span class="hlt">tail</span>'s angular impulse, especially at the highest forward velocities. PMID:27412267</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27124813','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27124813"><span>Langmuir monolayers composed of single and double <span class="hlt">tail</span> sulfobetaine lipids.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hazell, Gavin; Gee, Anthony P; Arnold, Thomas; Edler, Karen J; Lewis, Simon E</p> <p>2016-07-15</p> <p>Owing to structural similarities between sulfobetaine lipids and phospholipids it should be possible to form stable Langmuir monolayers from long <span class="hlt">tail</span> sulfobetaines. By modification of the density of lipid <span class="hlt">tail</span> group (number of carbon chains) it should also be possible to modulate the two-dimensional phase behaviour of these lipids and thereby compare with that of equivalent phospholipids. Potentially this could enable the use of such lipids for the wide array of applications that <span class="hlt">currently</span> use phospholipids. The benefit of using sulfobetaine lipids is that they can be synthesised by a one-step reaction from cheap and readily available starting materials and will degrade via different pathways than natural lipids. The molecular architecture of the lipid can be easily modified allowing the design of lipids for specific purposes. In addition the reversal of the charge within the sulfobetaine head group relative to the charge orientation in phospholipids may modify behaviour and thereby allow for novel uses of these surfactants. Stable Langmuir monolayers were formed composed of single and double <span class="hlt">tailed</span> sulfobetaine lipids. Surface pressure-area isotherm, Brewster Angle Microscopy and X-ray and neutron reflectometry measurements were conducted to measure the two-dimensional phase behaviour and out-of-plane structure of the monolayers as a function of molecular area. Sulfobetaine lipids are able to form stable Langmuir monolayers with two dimensional phase behaviour analogous to that seen for the well-studied phospholipids. Changing the number of carbon <span class="hlt">tail</span> groups on the lipid from one to two promotes the existence of a liquid condensed phase due to increased Van der Waals interactions between the <span class="hlt">tail</span> groups. Thus the structure of the monolayers appears to be defined by the relative sizes of the head and <span class="hlt">tail</span> groups in a predictable way. However, the presence of sub-phase ions has little effect on the monolayer structure, behaviour that is surprisingly different to</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19930091556','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19930091556"><span>Wing-Fuselage Interference, <span class="hlt">Tail</span> Buffeting, and Air Flow About the <span class="hlt">Tail</span> of a Low-Wing Monoplane</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>White, James A; Hood, Manley J</p> <p>1935-01-01</p> <p>This report presents the results of wind tunnel tests on a Mcdonnell Douglas airplane to determine the wing-fuselage interference of a low-wing monoplane. The tests included a study of <span class="hlt">tail</span> buffeting and the air flow in the region of the <span class="hlt">tail</span>. The airplane was tested with and without the propeller slipstream, both in the original condition and with several devices designed to reduce or eliminate <span class="hlt">tail</span> buffeting. The devices used were wing-fuselage fillets, a NACA cowling, reflexed trailing edge of the wing, and stub auxiliary airfoils.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19830037071&hterms=quasi+particle&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dquasi%2Bparticle','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19830037071&hterms=quasi+particle&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dquasi%2Bparticle"><span>Thermal and suprathermal protons and alpha particles in the earth's plasma <span class="hlt">sheet</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Ipavich, F. M.; Scholer, M.</p> <p>1983-01-01</p> <p>Detailed proton energy spectra in the quasi-stable distant plasma <span class="hlt">sheet</span> over the energy range from approximately 13 keV to approximately 130 keV are presented. These spectra are compared with spectra of simultaneously measured alpha particles in the energy range from approximately 30 keV/Q to approximately 130 keV/Q. The proton spectra are then extended into the higher energy range up to approximately 1 MeV, thereby supplementing the study of Sarris et al. (1981). The temporal behavior of the spectra in the higher energy range is discussed. It is found that below about 16 keV the proton spectra can be represented by a Maxwellian distribution; above this level, a suprathermal <span class="hlt">tail</span> is found that cannot be represented by a single power law.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015SHPMP..49...10M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015SHPMP..49...10M"><span>Four <span class="hlt">tails</span> problems for dynamical collapse theories</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>McQueen, Kelvin J.</p> <p>2015-02-01</p> <p>The primary quantum mechanical equation of motion entails that measurements typically do not have determinate outcomes, but result in superpositions of all possible outcomes. Dynamical collapse theories (e.g. GRW) supplement this equation with a stochastic Gaussian collapse function, intended to collapse the superposition of outcomes into one outcome. But the Gaussian collapses are imperfect in a way that leaves the superpositions intact. This is the <span class="hlt">tails</span> problem. There are several ways of making this problem more precise. But many authors dismiss the problem without considering the more severe formulations. Here I distinguish four distinct <span class="hlt">tails</span> problems. The first (bare <span class="hlt">tails</span> problem) and second (structured <span class="hlt">tails</span> problem) exist in the literature. I argue that while the first is a pseudo-problem, the second has not been adequately addressed. The third (multiverse <span class="hlt">tails</span> problem) reformulates the second to account for recently discovered dynamical consequences of collapse. Finally the fourth (<span class="hlt">tails</span> problem dilemma) shows that solving the third by replacing the Gaussian with a non-Gaussian collapse function introduces new conflict with relativity theory.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24196793','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24196793"><span>Carrier induced magnetic coupling transitions in phthalocyanine-based organometallic <span class="hlt">sheet</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhou, Jian; Sun, Qiang</p> <p>2014-01-07</p> <p>A two-dimensional <span class="hlt">sheet</span> with long range ferromagnetic (FM) order has been hotly pursued <span class="hlt">currently</span>. The recent success in synthesizing polymerized Fe-phthalocyanine (poly-FePc) porous <span class="hlt">sheets</span> paves a possible way to achieve this goal. However, the poly-FePc and its analog poly-CrPc structure are intrinsically antiferromagnetic (AFM). Using first principles combined with Monte-Carlo simulations, we study systematically the carrier-induced magnetic coupling transitions in poly-CrPc and poly-FePc <span class="hlt">sheets</span>. We show that electron doping can induce stable FM states with Curie temperatures of 130-140 K, while hole doping will enhance the stability of the AFM states. Such changes in magnetic couplings depend on the balance of AFM superexchange and FM p-d exchange.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27177891','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27177891"><span>Necrosis of the <span class="hlt">tail</span> of pancreas following proximal splenic artery embolization.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Talving, Peep; Rauk, Mariliis; Vipp, Liisa; Isand, Karl-Gunnar; Šamarin, Aleksandr; Põder, Kalle; Rätsep, Indrek; Saar, Sten</p> <p>2016-05-13</p> <p>The <span class="hlt">current</span> case report presents a rare complication of a significant pancreatic <span class="hlt">tail</span> necrosis following proximal splenic artery embolization in a 32-year-old male patient involved in a motorcycle accident. Proximal angiographic embolization of the splenic injury after trauma is a widely accepted method with excellent success rate; however, possible complications may occur and has been described in the literature. Nevertheless, only a few case reports pertinent to clinically significant pancreatic <span class="hlt">tail</span> necrosis after the SAE has been reported. Thus, we add a case report to the scarce literature pertinent to this detrimental and rare complication. Published by Oxford University Press and JSCR Publishing Ltd. All rights reserved. © The Author 2016.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1994JMMM..133..396M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1994JMMM..133..396M"><span>Analysis and comparison of magnetic <span class="hlt">sheet</span> insulation tests</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Marion-Péra, M. C.; Kedous-Lebouc, A.; Cornut, B.; Brissonneau, P.</p> <p>1994-05-01</p> <p>Magnetic circuits of electrical machines are divided into coated <span class="hlt">sheets</span> in order to limit eddy <span class="hlt">currents</span>. The surface insulation resistance of magnetic <span class="hlt">sheets</span> is difficult to evaluate because it depends on parameters like pressure and covers a wide range of values. Two methods of measuring insulation resistance are analyzed: the standardized 'Franklin device' and a tester developed by British Steel Electrical. Their main drawback is poor local repeatability. The Franklin method allows better quality control of industrial process because it measures only one insulating layer at a time. It also gives more accurate images of the distribution of possible defects. Nevertheless, both methods lead to similar classifications of insulation efficiency.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19980232234','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19980232234"><span>Some Effects of Horizontal-<span class="hlt">Tail</span> Position on the Vertical-<span class="hlt">Tail</span> Pressure Distributions of a Complete Model in Sideslip at High Subsonic Speeds</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Alford, William J., Jr.</p> <p>1958-01-01</p> <p>An investigation has been made in the Langley high-speed 7- by 10-foot tunnel of some effects of horizontal-<span class="hlt">tail</span> position on the vertical-<span class="hlt">tail</span> pressure distributions of a complete model in sideslip at high subsonic speeds. The wing of the model was swept back 28.82 deg at the quarter-chord line and had an aspect ratio of 3.50, a taper ratio of 0.067, and NACA 65A004 airfoil sections parallel to the model plane of symmetry. Tests were made with the horizontal <span class="hlt">tail</span> off, on the wing-chord plane extended, and in T-<span class="hlt">tail</span> arrangements in forward and rearward locations. The test Mach numbers ranged from 0.60 to 0.92, which corresponds to a Reynolds number range from approximately 2.93 x 10(exp 6) to 3.69 x 10(exp 6), based on the wing mean aerodynamic chord. The sideslip angles varied from -3.9 deg to 12.7 deg at several selected angles of attack. The results indicated that, for a given angle of sideslip, increases in angle of attack caused reductions in the vertical-<span class="hlt">tail</span> loads in the vicinity of the root chord and increases at the midspan and tip locations, with rearward movements in the local chordwise centers of pressure for the midspan locations and forward movements near the tip of the vertical <span class="hlt">tail</span>. At the higher angles of attack all configurations investigated experienced outboard and rearward shifts in the center of pressure of the total vertical-<span class="hlt">tail</span> load. Location of the horizontal <span class="hlt">tail</span> on the wing- chord plane extended produced only small effects on the vertical-<span class="hlt">tail</span> loads and centers of pressure. Locating the horizontal <span class="hlt">tail</span> at the tip of the vertical <span class="hlt">tail</span> in the forward position caused increases in the vertical-<span class="hlt">tail</span> loads; this configuration, however, experienced considerable reduction in loads with increasing Mach number. Location of the horizontal <span class="hlt">tail</span> at the tip of the vertical <span class="hlt">tail</span> in the rearward position produced the largest increases in vertical-<span class="hlt">tail</span> loads per degree sideslip angle; this configuration experienced the smallest variations of loads with</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017Natur.541...72B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017Natur.541...72B"><span>Centennial-scale Holocene climate variations amplified by Antarctic Ice <span class="hlt">Sheet</span> discharge</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bakker, Pepijn; Clark, Peter U.; Golledge, Nicholas R.; Schmittner, Andreas; Weber, Michael E.</p> <p>2017-01-01</p> <p>Proxy-based indicators of past climate change show that <span class="hlt">current</span> global climate models systematically underestimate Holocene-epoch climate variability on centennial to multi-millennial timescales, with the mismatch increasing for longer periods. Proposed explanations for the discrepancy include ocean-atmosphere coupling that is too weak in models, insufficient energy cascades from smaller to larger spatial and temporal scales, or that global climate models do not consider slow climate feedbacks related to the carbon cycle or interactions between ice <span class="hlt">sheets</span> and climate. Such interactions, however, are known to have strongly affected centennial- to orbital-scale climate variability during past glaciations, and are likely to be important in future climate change. Here we show that fluctuations in Antarctic Ice <span class="hlt">Sheet</span> discharge caused by relatively small changes in subsurface ocean temperature can amplify multi-centennial climate variability regionally and globally, suggesting that a dynamic Antarctic Ice <span class="hlt">Sheet</span> may have driven climate fluctuations during the Holocene. We analysed high-temporal-resolution records of iceberg-rafted debris derived from the Antarctic Ice <span class="hlt">Sheet</span>, and performed both high-spatial-resolution ice-<span class="hlt">sheet</span> modelling of the Antarctic Ice <span class="hlt">Sheet</span> and multi-millennial global climate model simulations. Ice-<span class="hlt">sheet</span> responses to decadal-scale ocean forcing appear to be less important, possibly indicating that the future response of the Antarctic Ice <span class="hlt">Sheet</span> will be governed more by long-term anthropogenic warming combined with multi-centennial natural variability than by annual or decadal climate oscillations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20010124875&hterms=sodium&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dsodium','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20010124875&hterms=sodium&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dsodium"><span>The Distant Sodium <span class="hlt">Tail</span> of Mercury</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Potter, A. E.; Killen, R. M.; Morgan, T. H.</p> <p>2001-01-01</p> <p>Models of the sodium atmosphere of Mercury predict the possible existence of a cornet-like sodium <span class="hlt">tail</span>. Detection and mapping of the predicted sodium <span class="hlt">tail</span> would provide quantitative data on the energy of the process that produces sodium atoms from the planetary surface. Previous efforts to detect the sodium <span class="hlt">tail</span> by means of observations done during daylight hours have been only partially successful because scattered sunlight obscured the weak sodium emissions in the <span class="hlt">tail</span>. However, at greatest eastern elongation around the March equinox in the northern hemisphere, Mercury can be seen as an evening star in astronomical twilight. At this time, the intensity of scattered sunlight is low enough that sodium emissions as low as 500 Rayleighs can be detected. Additional information is contained in the original extended abstract.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22066471-resistance-spot-welding-ultra-fine-grained-steel-sheets-produced-constrained-groove-pressing-optimization-characterization','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22066471-resistance-spot-welding-ultra-fine-grained-steel-sheets-produced-constrained-groove-pressing-optimization-characterization"><span>Resistance spot welding of ultra-fine grained steel <span class="hlt">sheets</span> produced by constrained groove pressing: Optimization and characterization</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Khodabakhshi, F.; Kazeminezhad, M., E-mail: mkazemi@sharif.edu; Kokabi, A.H.</p> <p>2012-07-15</p> <p>Constrained groove pressing as a severe plastic deformation method is utilized to produce ultra-fine grained low carbon steel <span class="hlt">sheets</span>. The ultra-fine grained <span class="hlt">sheets</span> are joined via resistance spot welding process and the characteristics of spot welds are investigated. Resistance spot welding process is optimized for welding of the <span class="hlt">sheets</span> with different severe deformations and their results are compared with those of as-received samples. The effects of failure mode and expulsion on the performance of ultra-fine grained <span class="hlt">sheet</span> spot welds have been investigated in the present paper and the welding <span class="hlt">current</span> and time of resistance spot welding process according to thesemore » subjects are optimized. Failure mode and failure load obtained in tensile-shear test, microhardness, X-ray diffraction, transmission electron microscope and scanning electron microscope images have been used to describe the performance of spot welds. The region between interfacial to pullout mode transition and expulsion limit is defined as the optimum welding condition. The results show that optimum welding parameters (welding <span class="hlt">current</span> and welding time) for ultra-fine grained <span class="hlt">sheets</span> are shifted to lower values with respect to those for as-received specimens. In ultra-fine grained <span class="hlt">sheets</span>, one new region is formed named recrystallized zone in addition to fusion zone, heat affected zone and base metal. It is shown that microstructures of different zones in ultra-fine grained <span class="hlt">sheets</span> are finer than those of as-received <span class="hlt">sheets</span>. - Highlights: Black-Right-Pointing-Pointer Resistance spot welding process is optimized for joining of UFG steel <span class="hlt">sheets</span>. Black-Right-Pointing-Pointer Optimum welding <span class="hlt">current</span> and time are decreased with increasing the CGP pass number. Black-Right-Pointing-Pointer Microhardness at BM, HAZ, FZ and recrystallized zone is enhanced due to CGP.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017DPS....4942201S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017DPS....4942201S"><span>Detection of Mercury's Potassium <span class="hlt">Tail</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schmidt, Carl; Leblanc, Francois; Moore, Luke; Bida, Thomas A.</p> <p>2017-10-01</p> <p>Ground-based observations of Mercury's exosphere bridge the gap between the MESSENGER and BepiColombo missions and provide a broad counterpart to their in situ measurements. Here we report the first detection of Mercury's potassium <span class="hlt">tail</span> in both emission lines of the D doublet. The sodium to potassium abundance ratio at 5 planetary radii down-<span class="hlt">tail</span> is approximately 95, near the mid-point of a wide range of values that have been quoted over the planet's disk. This is several times the Na/K present in atmospheres of the Galilean satellites and more than an order of magnitude above Mercury's usual analogue, the Moon. The observations confirm that Mercury's anomalously high Na/K ratios cannot be explained by differences in neutral loss rates. The width and structure of the Na and K <span class="hlt">tails</span> is comparable and both exhibit a persistent enhancement in their northern lobe. We interpret this as a signature of Mercury's offset magnetosphere; the exosphere's source rates are locally enhanced at the southern surface, and sloshing from radiation pressure and gravity guides this population into the northern region of the <span class="hlt">tail</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFMGP31A1094T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFMGP31A1094T"><span>Large-scale flows, <span class="hlt">sheet</span> plumes and strong magnetic fields in a rapidly rotating spherical dynamo</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Takahashi, F.</p> <p>2011-12-01</p> <p>Mechanisms of magnetic field intensification by flows of an electrically conducting fluid in a rapidly rotating spherical shell is investigated. Bearing dynamos of the Eartn and planets in mind, the Ekman number is set at 10-5. A strong dipolar solution with magnetic energy 55 times larger than the kinetic energy of thermal convection is obtained. In a regime of small viscosity and inertia with the strong magnetic field, convection structure consists of a few large-scale retrograde flows in the azimuthal direction and sporadic thin <span class="hlt">sheet</span>-like plumes. The magnetic field is amplified through stretching of magnetic lines, which occurs typically through three types of flow: the retrograde azimuthal flow near the outer boundary, the downwelling flow of the <span class="hlt">sheet</span> plume, and the prograde azimuthal flow near the rim of the tangent cylinder induced by the downwelling flow. It is found that either structure of <span class="hlt">current</span> loops or <span class="hlt">current</span> <span class="hlt">sheets</span> is accompanied in each flow structure. <span class="hlt">Current</span> loops emerge as a result of stretching the magnetic lines along the magnetic field, wheres the <span class="hlt">current</span> <span class="hlt">sheets</span> are formed to counterbalance the Coriolis force. Convection structure and processes of magnetic field generation found in the present model are distinct from those in models at larger/smaller Ekman number.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_23 --> <div id="page_24" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active"><span>24</span></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="461"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19830000204&hterms=tapping&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dtapping','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19830000204&hterms=tapping&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dtapping"><span>Transporter for Treated <span class="hlt">Sheet</span> Materials</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Pollack, M., H.</p> <p>1983-01-01</p> <p>Plastic spacers keep parts separated during transport or storage. Cart with rods and spacers holds <span class="hlt">sheets</span> with delicate finishes for storage or transport. <span class="hlt">Sheets</span> supported vertically by rods, or horizontally. Spacers keep <span class="hlt">sheets</span> separated. Designed to eliminate time and expense of tapping, wrapping, and sometimes refinishing aluminum <span class="hlt">sheets</span> with delicate anodized finished.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19850000125&hterms=baking&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dbaking','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19850000125&hterms=baking&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dbaking"><span>Perforating Thin Metal <span class="hlt">Sheets</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Davidson, M. E.</p> <p>1985-01-01</p> <p><span class="hlt">Sheets</span> only few mils thick bonded together, punched, then debonded. Three-step process yields perforated <span class="hlt">sheets</span> of metal. (1): Individual <span class="hlt">sheets</span> bonded together to form laminate. (2): laminate perforated in desired geometric pattern. (3): After baking, laminate separates into individual <span class="hlt">sheets</span>. Developed for fabricating conductive layer on blankets that collect and remove ions; however, perforated foils have other applications - as conductive surfaces on insulating materials; stiffeners and conductors in plastic laminates; reflectors in antenna dishes; supports for thermal blankets; lightweight grille cover materials; and material for mockup of components.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://rosap.ntl.bts.gov/view/dot/18707','DOTNTL'); return false;" href="https://rosap.ntl.bts.gov/view/dot/18707"><span>Evaluation of high intensity <span class="hlt">sheeting</span> for overhead highway signs.</span></a></p> <p><a target="_blank" href="http://ntlsearch.bts.gov/tris/index.do">DOT National Transportation Integrated Search</a></p> <p></p> <p>1974-01-01</p> <p>The <span class="hlt">current</span> practice in Virginia is to reflectorize and illuminate all overhead highway signs because of their important role in the safe and orderly flow of traffic. Reflectorization is obtained by using reflective <span class="hlt">sheeting</span> as background and legend ...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70168726','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70168726"><span>Black-<span class="hlt">tailed</span> and white-<span class="hlt">tailed</span> jackrabbits in the American West: History, ecology, ecological significance, and survey methods</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Simes, Matthew; Longshore, Kathleen M.; Nussear, Kenneth E.; Beatty, Greg L.; Brown, David E.; Esque, Todd C.</p> <p>2015-01-01</p> <p>Across the western United States, Leporidae are the most important prey item in the diet of Golden Eagles (Aquila chrysaetos). Leporids inhabiting the western United States include black-<span class="hlt">tailed</span> (Lepus californicus) and white-<span class="hlt">tailed</span> jackrabbits (Lepus townsendii) and various species of cottontail rabbit (Sylvilagus spp.). Jackrabbits (Lepus spp.) are particularly important components of the ecological and economic landscape of western North America because their abundance influences the reproductive success and population trends of predators such as coyotes (Canis latrans), bobcats (Lynx rufus), and a number of raptor species. Here, we review literature pertaining to black-<span class="hlt">tailed</span> and white-<span class="hlt">tailed</span> jackrabbits comprising over 170 published journal articles, notes, technical reports, conference proceedings, academic theses and dissertations, and other sources dating from the late 19th century to the present. Our goal is to present information to assist those in research and management, particularly with regard to protected raptor species (e.g., Golden Eagles), mammalian predators, and ecological monitoring. We classified literature sources as (1) general information on jackrabbit species, (2) black-<span class="hlt">tailed</span> or (3) white-<span class="hlt">tailed</span> jackrabbit ecology and natural history, or (4) survey methods. These categories, especially 2, 3, and 4, were further subdivided as appropriate. The review also produced several tables on population trends, food habits, densities within various habitats, and jackrabbit growth and development. Black-<span class="hlt">tailed</span> and white-<span class="hlt">tailed</span> jackrabbits are ecologically similar in general behaviors, use of forms, parasites, and food habits, and they are prey to similar predators; but they differ in their preferred habitats. While the black-<span class="hlt">tailed</span> jackrabbit inhabits agricultural land, deserts, and shrublands, the white-<span class="hlt">tailed</span> jackrabbit is associated with prairies, alpine tundra, and sagebrush-steppe. Frequently considered abundant, jackrabbit numbers in western North</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017GMD....10..255P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017GMD....10..255P"><span>An ice <span class="hlt">sheet</span> model validation framework for the Greenland ice <span class="hlt">sheet</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Price, Stephen F.; Hoffman, Matthew J.; Bonin, Jennifer A.; Howat, Ian M.; Neumann, Thomas; Saba, Jack; Tezaur, Irina; Guerber, Jeffrey; Chambers, Don P.; Evans, Katherine J.; Kennedy, Joseph H.; Lenaerts, Jan; Lipscomb, William H.; Perego, Mauro; Salinger, Andrew G.; Tuminaro, Raymond S.; van den Broeke, Michiel R.; Nowicki, Sophie M. J.</p> <p>2017-01-01</p> <p>We propose a new ice <span class="hlt">sheet</span> model validation framework - the Cryospheric Model Comparison Tool (CmCt) - that takes advantage of ice <span class="hlt">sheet</span> altimetry and gravimetry observations collected over the past several decades and is applied here to modeling of the Greenland ice <span class="hlt">sheet</span>. We use realistic simulations performed with the Community Ice <span class="hlt">Sheet</span> Model (CISM) along with two idealized, non-dynamic models to demonstrate the framework and its use. Dynamic simulations with CISM are forced from 1991 to 2013, using combinations of reanalysis-based surface mass balance and observations of outlet glacier flux change. We propose and demonstrate qualitative and quantitative metrics for use in evaluating the different model simulations against the observations. We find that the altimetry observations used here are largely ambiguous in terms of their ability to distinguish one simulation from another. Based on basin-scale and whole-ice-<span class="hlt">sheet</span>-scale metrics, we find that simulations using both idealized conceptual models and dynamic, numerical models provide an equally reasonable representation of the ice <span class="hlt">sheet</span> surface (mean elevation differences of < 1 m). This is likely due to their short period of record, biases inherent to digital elevation models used for model initial conditions, and biases resulting from firn dynamics, which are not explicitly accounted for in the models or observations. On the other hand, we find that the gravimetry observations used here are able to unambiguously distinguish between simulations of varying complexity, and along with the CmCt, can provide a quantitative score for assessing a particular model and/or simulation. The new framework demonstrates that our proposed metrics can distinguish relatively better from relatively worse simulations and that dynamic ice <span class="hlt">sheet</span> models, when appropriately initialized and forced with the right boundary conditions, demonstrate a predictive skill with respect to observed dynamic changes that have occurred on</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1340442','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/1340442"><span>An ice <span class="hlt">sheet</span> model validation framework for the Greenland ice <span class="hlt">sheet</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Price, Stephen F.; Hoffman, Matthew J.; Bonin, Jennifer A.</p> <p></p> <p>We propose a new ice <span class="hlt">sheet</span> model validation framework the Cryospheric Model Comparison Tool (CMCT) that takes advantage of ice <span class="hlt">sheet</span> altimetry and gravimetry observations collected over the past several decades and is applied here to modeling of the Greenland ice <span class="hlt">sheet</span>. We use realistic simulations performed with the Community Ice <span class="hlt">Sheet</span> Model (CISM) along with two idealized, non-dynamic models to demonstrate the framework and its use. Dynamic simulations with CISM are forced from 1991 to 2013 using combinations of reanalysis-based surface mass balance and observations of outlet glacier flux change. We propose and demonstrate qualitative and quanti- tative metricsmore » for use in evaluating the different model simulations against the observations. We find 10 that the altimetry observations used here are largely ambiguous in terms of their ability to distinguish one simulation from another. Based on basin- and whole-ice-<span class="hlt">sheet</span> scale metrics, the model initial condition as well as output from idealized and dynamic models all provide an equally reasonable representation of the ice <span class="hlt">sheet</span> surface (mean elevation differences of <1 m). This is likely due to their short period of record, biases inherent to digital elevation models used for model initial conditions, and biases resulting from firn dynamics, which are not explicitly accounted for in the models or observations. On the other hand, we find that the gravimetry observations used here are able to unambiguously distinguish between simulations of varying complexity, and along with the CMCT, can provide a quantitative score for assessing a particular model and/or simulation. The new framework demonstrates that our proposed metrics can distinguish relatively better from relatively worse simulations and that dynamic ice <span class="hlt">sheet</span> models, when appropriately initialized and forced with the right boundary conditions, demonstrate predictive skill with respect to observed dynamic changes occurring on Greenland over the past few</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5911937','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5911937"><span>An ice <span class="hlt">sheet</span> model validation framework for the Greenland ice <span class="hlt">sheet</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Price, Stephen F.; Hoffman, Matthew J.; Bonin, Jennifer A.; Howat, Ian M.; Neumann, Thomas; Saba, Jack; Tezaur, Irina; Guerber, Jeffrey; Chambers, Don P.; Evans, Katherine J.; Kennedy, Joseph H.; Lenaerts, Jan; Lipscomb, William H.; Perego, Mauro; Salinger, Andrew G.; Tuminaro, Raymond S.; van den Broeke, Michiel R.; Nowicki, Sophie M. J.</p> <p>2018-01-01</p> <p>We propose a new ice <span class="hlt">sheet</span> model validation framework – the Cryospheric Model Comparison Tool (CmCt) – that takes advantage of ice <span class="hlt">sheet</span> altimetry and gravimetry observations collected over the past several decades and is applied here to modeling of the Greenland ice <span class="hlt">sheet</span>. We use realistic simulations performed with the Community Ice <span class="hlt">Sheet</span> Model (CISM) along with two idealized, non-dynamic models to demonstrate the framework and its use. Dynamic simulations with CISM are forced from 1991 to 2013 using combinations of reanalysis-based surface mass balance and observations of outlet glacier flux change. We propose and demonstrate qualitative and quantitative metrics for use in evaluating the different model simulations against the observations. We find that the altimetry observations used here are largely ambiguous in terms of their ability to distinguish one simulation from another. Based on basin- and whole-ice-<span class="hlt">sheet</span> scale metrics, we find that simulations using both idealized conceptual models and dynamic, numerical models provide an equally reasonable representation of the ice <span class="hlt">sheet</span> surface (mean elevation differences of <1 m). This is likely due to their short period of record, biases inherent to digital elevation models used for model initial conditions, and biases resulting from firn dynamics, which are not explicitly accounted for in the models or observations. On the other hand, we find that the gravimetry observations used here are able to unambiguously distinguish between simulations of varying complexity, and along with the CmCt, can provide a quantitative score for assessing a particular model and/or simulation. The new framework demonstrates that our proposed metrics can distinguish relatively better from relatively worse simulations and that dynamic ice <span class="hlt">sheet</span> models, when appropriately initialized and forced with the right boundary conditions, demonstrate predictive skill with respect to observed dynamic changes occurring on Greenland over the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29697704','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29697704"><span>An ice <span class="hlt">sheet</span> model validation framework for the Greenland ice <span class="hlt">sheet</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Price, Stephen F; Hoffman, Matthew J; Bonin, Jennifer A; Howat, Ian M; Neumann, Thomas; Saba, Jack; Tezaur, Irina; Guerber, Jeffrey; Chambers, Don P; Evans, Katherine J; Kennedy, Joseph H; Lenaerts, Jan; Lipscomb, William H; Perego, Mauro; Salinger, Andrew G; Tuminaro, Raymond S; van den Broeke, Michiel R; Nowicki, Sophie M J</p> <p>2017-01-01</p> <p>We propose a new ice <span class="hlt">sheet</span> model validation framework - the Cryospheric Model Comparison Tool (CmCt) - that takes advantage of ice <span class="hlt">sheet</span> altimetry and gravimetry observations collected over the past several decades and is applied here to modeling of the Greenland ice <span class="hlt">sheet</span>. We use realistic simulations performed with the Community Ice <span class="hlt">Sheet</span> Model (CISM) along with two idealized, non-dynamic models to demonstrate the framework and its use. Dynamic simulations with CISM are forced from 1991 to 2013 using combinations of reanalysis-based surface mass balance and observations of outlet glacier flux change. We propose and demonstrate qualitative and quantitative metrics for use in evaluating the different model simulations against the observations. We find that the altimetry observations used here are largely ambiguous in terms of their ability to distinguish one simulation from another. Based on basin- and whole-ice-<span class="hlt">sheet</span> scale metrics, we find that simulations using both idealized conceptual models and dynamic, numerical models provide an equally reasonable representation of the ice <span class="hlt">sheet</span> surface (mean elevation differences of <1 m). This is likely due to their short period of record, biases inherent to digital elevation models used for model initial conditions, and biases resulting from firn dynamics, which are not explicitly accounted for in the models or observations. On the other hand, we find that the gravimetry observations used here are able to unambiguously distinguish between simulations of varying complexity, and along with the CmCt, can provide a quantitative score for assessing a particular model and/or simulation. The new framework demonstrates that our proposed metrics can distinguish relatively better from relatively worse simulations and that dynamic ice <span class="hlt">sheet</span> models, when appropriately initialized and forced with the right boundary conditions, demonstrate predictive skill with respect to observed dynamic changes occurring on Greenland over the past</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1340442-ice-sheet-model-validation-framework-greenland-ice-sheet','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1340442-ice-sheet-model-validation-framework-greenland-ice-sheet"><span>An ice <span class="hlt">sheet</span> model validation framework for the Greenland ice <span class="hlt">sheet</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Price, Stephen F.; Hoffman, Matthew J.; Bonin, Jennifer A.; ...</p> <p>2017-01-17</p> <p>We propose a new ice <span class="hlt">sheet</span> model validation framework the Cryospheric Model Comparison Tool (CMCT) that takes advantage of ice <span class="hlt">sheet</span> altimetry and gravimetry observations collected over the past several decades and is applied here to modeling of the Greenland ice <span class="hlt">sheet</span>. We use realistic simulations performed with the Community Ice <span class="hlt">Sheet</span> Model (CISM) along with two idealized, non-dynamic models to demonstrate the framework and its use. Dynamic simulations with CISM are forced from 1991 to 2013 using combinations of reanalysis-based surface mass balance and observations of outlet glacier flux change. We propose and demonstrate qualitative and quanti- tative metricsmore » for use in evaluating the different model simulations against the observations. We find 10 that the altimetry observations used here are largely ambiguous in terms of their ability to distinguish one simulation from another. Based on basin- and whole-ice-<span class="hlt">sheet</span> scale metrics, the model initial condition as well as output from idealized and dynamic models all provide an equally reasonable representation of the ice <span class="hlt">sheet</span> surface (mean elevation differences of <1 m). This is likely due to their short period of record, biases inherent to digital elevation models used for model initial conditions, and biases resulting from firn dynamics, which are not explicitly accounted for in the models or observations. On the other hand, we find that the gravimetry observations used here are able to unambiguously distinguish between simulations of varying complexity, and along with the CMCT, can provide a quantitative score for assessing a particular model and/or simulation. The new framework demonstrates that our proposed metrics can distinguish relatively better from relatively worse simulations and that dynamic ice <span class="hlt">sheet</span> models, when appropriately initialized and forced with the right boundary conditions, demonstrate predictive skill with respect to observed dynamic changes occurring on Greenland over the past few</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20170003152','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20170003152"><span>An Ice <span class="hlt">Sheet</span> Model Validation Framework for the Greenland Ice <span class="hlt">Sheet</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Price, Stephen F.; Hoffman, Matthew J.; Bonin, Jennifer A.; Howat, Ian M.; Neumann, Thomas A.; Saba, Jack; Tezaur, Irina; Guerber, Jeffrey R.; Chambers, Don P.; Evans, Katherine J.; <a style="text-decoration: none; " href="javascript:void(0); " onClick="displayelement('author_20170003152'); toggleEditAbsImage('author_20170003152_show'); toggleEditAbsImage('author_20170003152_hide'); "> <img style="display:inline; width:12px; height:12px; " src="images/arrow-up.gif" width="12" height="12" border="0" alt="hide" id="author_20170003152_show"> <img style="width:12px; height:12px; display:none; " src="images/arrow-down.gif" width="12" height="12" border="0" alt="hide" id="author_20170003152_hide"></p> <p>2017-01-01</p> <p>We propose a new ice <span class="hlt">sheet</span> model validation framework - the Cryospheric Model Comparison Tool (CmCt) - that takes advantage of ice <span class="hlt">sheet</span> altimetry and gravimetry observations collected over the past several decades and is applied here to modeling of the Greenland ice <span class="hlt">sheet</span>. We use realistic simulations performed with the Community Ice <span class="hlt">Sheet</span> Model (CISM) along with two idealized, non-dynamic models to demonstrate the framework and its use. Dynamic simulations with CISM are forced from 1991 to 2013, using combinations of reanalysis-based surface mass balance and observations of outlet glacier flux change. We propose and demonstrate qualitative and quantitative metrics for use in evaluating the different model simulations against the observations. We find that the altimetry observations used here are largely ambiguous in terms of their ability to distinguish one simulation from another. Based on basin-scale and whole-ice-<span class="hlt">sheet</span>-scale metrics, we find that simulations using both idealized conceptual models and dynamic, numerical models provide an equally reasonable representation of the ice <span class="hlt">sheet</span> surface (mean elevation differences of less than 1 meter). This is likely due to their short period of record, biases inherent to digital elevation models used for model initial conditions, and biases resulting from firn dynamics, which are not explicitly accounted for in the models or observations. On the other hand, we find that the gravimetry observations used here are able to unambiguously distinguish between simulations of varying complexity, and along with the CmCt, can provide a quantitative score for assessing a particular model and/or simulation. The new framework demonstrates that our proposed metrics can distinguish relatively better from relatively worse simulations and that dynamic ice <span class="hlt">sheet</span> models, when appropriately initialized and forced with the right boundary conditions, demonstrate a predictive skill with respect to observed dynamic changes that have occurred</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.H53Q..08C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.H53Q..08C"><span>Heavy <span class="hlt">Tail</span> Behavior of Rainfall Extremes across Germany</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Castellarin, A.; Kreibich, H.; Vorogushyn, S.; Merz, B.</p> <p>2017-12-01</p> <p>Distributions are termed heavy-<span class="hlt">tailed</span> if extreme values are more likely than would be predicted by probability distributions that have exponential asymptotic behavior. Heavy-<span class="hlt">tail</span> behavior often leads to surprise, because historical observations can be a poor guide for the future. Heavy-<span class="hlt">tail</span> behavior seems to be widespread for hydro-meteorological extremes, such as extreme rainfall and flood events. To date there have been only vague hints to explain under which conditions these extremes show heavy-<span class="hlt">tail</span> behavior. We use an observational data set consisting of 11 climate variables at 1440 stations across Germany. This homogenized, gap-free data set covers 110 years (1901-2010) at daily resolution. We estimate the upper <span class="hlt">tail</span> behavior, including its uncertainty interval, of daily precipitation extremes for the 1,440 stations at the annual and seasonal time scales. Different <span class="hlt">tail</span> indicators are tested, including the shape parameter of the Generalized Extreme Value distribution, the upper <span class="hlt">tail</span> ratio and the obesity index. In a further step, we explore to which extent the <span class="hlt">tail</span> behavior can be explained by geographical and climate factors. A large number of characteristics is derived, such as station elevation, degree of continentality, aridity, measures for quantifying the variability of humidity and wind velocity, or event-triggering large-scale atmospheric situation. The link between the upper <span class="hlt">tail</span> behavior and these characteristics is investigated via data mining methods capable of detecting non-linear relationships in large data sets. This exceptionally rich observational data set, in terms of number of stations, length of time series and number of explaining variables, allows insights into the upper <span class="hlt">tail</span> behavior which is rarely possible given the typical observational data sets available.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27412267','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27412267"><span>Quasi-steady state aerodynamics of the cheetah <span class="hlt">tail</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Patel, Amir; Boje, Edward; Fisher, Callen; Louis, Leeann; Lane, Emily</p> <p>2016-08-15</p> <p>During high-speed pursuit of prey, the cheetah (Acinonyx jubatus) has been observed to swing its <span class="hlt">tail</span> while manoeuvring (e.g. turning or braking) but the effect of these complex motions is not well understood. This study demonstrates the potential of the cheetah's long, furry <span class="hlt">tail</span> to impart torques and forces on the body as a result of aerodynamic effects, in addition to the well-known inertial effects. The first-order aerodynamic forces on the <span class="hlt">tail</span> are quantified through wind tunnel testing and it is observed that the fur nearly doubles the effective frontal area of the <span class="hlt">tail</span> without much mass penalty. Simple dynamic models provide insight into manoeuvrability via simulation of pitch, roll and yaw <span class="hlt">tail</span> motion primitives. The inertial and quasi-steady state aerodynamic effects of <span class="hlt">tail</span> actuation are quantified and compared by calculating the angular impulse imparted onto the cheetah's body and its shown aerodynamic effects contribute to the <span class="hlt">tail</span>'s angular impulse, especially at the highest forward velocities. © 2016. Published by The Company of Biologists Ltd.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20130009433','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20130009433"><span><span class="hlt">Sheet</span> Membrane Spacesuit Water Membrane Evaporator</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Bue, Grant; Trevino, Luis; Zapata, Felipe; Dillion, Paul; Castillo, Juan; Vonau, Walter; Wilkes, Robert; Vogel, Matthew; Frodge, Curtis</p> <p>2013-01-01</p> <p>A document describes a <span class="hlt">sheet</span> membrane spacesuit water membrane evaporator (SWME), which allows for the use of one common water tank that can supply cooling water to the astronaut and to the evaporator. Test data showed that heat rejection performance dropped only 6 percent after being subjected to highly contaminated water. It also exhibited robustness with respect to freezing and Martian atmospheric simulation testing. Water was allowed to freeze in the water channels during testing that simulated a water loop failure and vapor backpressure valve failure. Upon closing the backpressure valve and energizing the pump, the ice eventually thawed and water began to flow with no apparent damage to the <span class="hlt">sheet</span> membrane. The membrane evaporator also serves to de-gas the water loop from entrained gases, thereby eliminating the need for special degassing equipment such as is needed by the <span class="hlt">current</span> spacesuit system. As water flows through the three annular water channels, water evaporates with the vapor flowing across the hydrophobic, porous <span class="hlt">sheet</span> membrane to the vacuum side of the membrane. The rate at which water evaporates, and therefore, the rate at which the flowing water is cooled, is a function of the difference between the water saturation pressure on the water side of the membrane, and the pressure on the vacuum side of the membrane. The primary theory is that the hydrophobic <span class="hlt">sheet</span> membrane retains water, but permits vapor pass-through when the vapor side pressure is less than the water saturation pressure. This results in evaporative cooling of the remaining water.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.loc.gov/pictures/collection/hh/item/ca3307.photos.197671p/','SCIGOV-HHH'); return false;" href="https://www.loc.gov/pictures/collection/hh/item/ca3307.photos.197671p/"><span>17. INTAKE PIER, BRIDGE STRESS <span class="hlt">SHEET</span>, <span class="hlt">SHEET</span> 8 OF 117, ...</span></a></p> <p><a target="_blank" href="http://www.loc.gov/pictures/collection/hh/">Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey</a></p> <p></p> <p></p> <p>17. INTAKE PIER, BRIDGE STRESS <span class="hlt">SHEET</span>, <span class="hlt">SHEET</span> 8 OF 117, 1920. - Sacramento River Water Treatment Plant Intake Pier & Access Bridge, Spanning Sacramento River approximately 175 feet west of eastern levee on river; roughly .5 mile downstream from confluence of Sacramento & American Rivers, Sacramento, Sacramento County, CA</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014MCM....50..669G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014MCM....50..669G"><span>Deformation Analysis of RC Ties Externally Strengthened with FRP <span class="hlt">Sheets</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gribniak, V.; Arnautov, A. K.; Kaklauskas, G.; Jakstaite, R.; Tamulenas, V.; Gudonis, E.</p> <p>2014-11-01</p> <p>The <span class="hlt">current</span> study has two objectives: to validate the ability of the Atena finite-element software to estimate the deformations of reinforced concrete (RC) elements strengthened with fiber-reinforced polymer (FRP) <span class="hlt">sheets</span> and to assess the effect of FRP-to-concrete bond strength on the results of numerical simulation. It is shown that the bond strength has to be selected according to the overall stiffness of the composite element. The numerical results found are corroborated experimentally by tensile tests of RC elements strengthened with basalt FRP <span class="hlt">sheets</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.fs.usda.gov/treesearch/pubs/30802','TREESEARCH'); return false;" href="https://www.fs.usda.gov/treesearch/pubs/30802"><span>Comparison of methods to estimate population densities of black-<span class="hlt">tailed</span> prairie dogs</span></a></p> <p><a target="_blank" href="http://www.fs.usda.gov/treesearch/">Treesearch</a></p> <p>Kieth E. Severson; Glenn E. Plumb</p> <p>1999-01-01</p> <p>Recent reintroduction of the black-footed ferret (Mustela nigripes) in west-central South Dakota has focused new attention on black-<span class="hlt">tailed</span> prairie dogs (Cynomys ludovicanus), because prairie dog colonies provide essential habitat for ferrets. <span class="hlt">Currently</span>, management agencies are assessing prairie dog populations by counting active...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20110004923&hterms=sodium&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dsodium','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20110004923&hterms=sodium&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dsodium"><span>The Sodium <span class="hlt">Tail</span> of the Moon</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Matta, M.; Smith, S.; Baumgardner, J.; Wilson, J.; Martinis, C.; Mendillo, M.</p> <p>2009-01-01</p> <p>During the few days centered about new Moon, the lunar surface is optically hidden from Earth-based observers. However, the Moon still offers an observable: an extended sodium <span class="hlt">tail</span>. The lunar sodium <span class="hlt">tail</span> is the escaping "hot" component of a coma-like exosphere of sodium generated by photon-stimulated desorption, solar wind sputtering and meteoroid impact. Neutral sodium atoms escaping lunar gravity experience solar radiation pressure that drives them into the anti-solar direction forming a comet-like <span class="hlt">tail</span>. During new Moon time, the geometry of the Sun, Moon and Earth is such that the anti-sunward sodium flux is perturbed by the terrestrial gravitational field resulting in its focusing into a dense core that extends beyond the Earth. An all-sky camera situated at the El Leoncito Observatory (CASLEO) in Argentina has been successfully imaging this <span class="hlt">tail</span> through a sodium filter at each lunation since April 2006. This paper reports on the results of the brightness of the lunar sodium <span class="hlt">tail</span> spanning 31 lunations between April 2006 and September 2008. Brightness variability trends are compared with both sporadic and shower meteor activity, solar wind proton energy flux and solar near ultra violet (NUV) patterns for possible correlations. Results suggest minimal variability in the brightness of the observed lunar sodium <span class="hlt">tail</span>, generally uncorrelated with any single source, yet consistent with a multi-year period of minimal solar activity and non-intense meteoric fluxes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4913084','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4913084"><span>Bovine Viral Diarrhea Virus (BVDV) in White-<span class="hlt">Tailed</span> Deer (Odocoileus virginianus)</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Passler, Thomas; Ditchkoff, Stephen S.; Walz, Paul H.</p> <p>2016-01-01</p> <p>Bovine viral diarrhea virus (BVDV) is the prototypic member of the genus Pestivirus in the family Flaviviridae. Infections with BVDV cause substantial economic losses to the cattle industries, prompting various organized control programs in several countries. In North America, these control programs are focused on the identification and removal of persistently infected (PI) cattle, enhancement of BVDV-specific immunity through vaccination, and the implementation of biosecure farming practices. To be successful, control measures must be based on complete knowledge of the epidemiology of BVDV, including the recognition of other potential sources of the virus. BVDV does not possess strict host-specificity, and infections of over 50 species in the mammalian order Artiodactyla have been reported. Over 50 years ago, serologic surveys first suggested the susceptibility of white-<span class="hlt">tailed</span> deer (Odocoileus virginianus), the most abundant free-ranging ruminant in North America, to BVDV. However, susceptibility of white-<span class="hlt">tailed</span> deer to BVDV infection does not alone imply a role in the epidemiology of the virus. To be a potential wildlife reservoir, white-<span class="hlt">tailed</span> deer must: (1) be susceptible to BVDV, (2) shed BVDV, (3) maintain BVDV in the population, and (4) have sufficient contact with cattle that allow spillback infections. Based on the <span class="hlt">current</span> literature, this review discusses the potential of white-<span class="hlt">tailed</span> deer to be a reservoir for BVDV. PMID:27379074</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009PhyA..388..691B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009PhyA..388..691B"><span>Physical space and long-<span class="hlt">tail</span> markets</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bentley, R. Alexander; Madsen, Mark E.; Ormerod, Paul</p> <p>2009-03-01</p> <p>The Internet is known to have had a powerful impact on on-line retailer strategies in markets characterised by long-<span class="hlt">tail</span> distribution of sales [C. Anderson, Long <span class="hlt">Tail</span>: Why the Future of Business is Selling Less of More, Hyperion, New York, 2006]. Such retailers can exploit the long <span class="hlt">tail</span> of the market, since they are effectively without physical limit on the number of choices on offer. Here we examine two extensions of this phenomenon. First, we introduce turnover into the long-<span class="hlt">tail</span> distribution of sales. Although over any given period such as a week or a month, the distribution is right-skewed and often power law distributed, over time there is considerable turnover in the rankings of sales of individual products. Second, we establish some initial results on the implications for shelf-space and physical retailers in such markets.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/871716','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/871716"><span>Method for heating a glass <span class="hlt">sheet</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Boaz, Premakaran Tucker</p> <p>1998-01-01</p> <p>A method for heating a glass <span class="hlt">sheet</span> includes the steps of heating a glass <span class="hlt">sheet</span> to a first predetermined temperature and applying microwave energy to the glass <span class="hlt">sheet</span> to heat the glass <span class="hlt">sheet</span> to at least a second predetermined temperature to allow the glass <span class="hlt">sheet</span> to be formed.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active"><span>24</span></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_24 --> <div id="page_25" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li class="active"><span>25</span></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="481"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5468947','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5468947"><span>Clinching for <span class="hlt">sheet</span> materials</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>He, Xiaocong</p> <p>2017-01-01</p> <p>Abstract Latest developments in the clinching of <span class="hlt">sheet</span> materials are reviewed in this article. Important issues are discussed, such as tool design, process parameters and joinability of some new lightweight <span class="hlt">sheet</span> materials. Hybrid and modified clinching processes are introduced to a general reader. Several unaddressed issues in the clinching of <span class="hlt">sheet</span> materials are identified. PMID:28656065</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19870009353','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19870009353"><span>Liquid <span class="hlt">sheet</span> radiator</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Chubb, Donald L.; White, K. Alan, III</p> <p>1987-01-01</p> <p>A new external flow radiator concept, the liquid <span class="hlt">sheet</span> radiator (LSR), is introduced. The LSR <span class="hlt">sheet</span> flow is described and an expression for the length/width (l/w), ratio is presented. A linear dependence of l/w on velocity is predicted that agrees with experimental results. Specific power for the LSR is calculated and is found to be nearly the same as the specific power of a liquid droplet radiator, (LDR). Several <span class="hlt">sheet</span> thicknesses and widths were experimentally investigated. In no case was the flow found to be unstable.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/672583','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/biblio/672583"><span>Method for heating a glass <span class="hlt">sheet</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Boaz, P.T.</p> <p>1998-07-21</p> <p>A method for heating a glass <span class="hlt">sheet</span> includes the steps of heating a glass <span class="hlt">sheet</span> to a first predetermined temperature and applying microwave energy to the glass <span class="hlt">sheet</span> to heat the glass <span class="hlt">sheet</span> to at least a second predetermined temperature to allow the glass <span class="hlt">sheet</span> to be formed. 5 figs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19950053475&hterms=Open+Field&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DOpen%2BField','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19950053475&hterms=Open+Field&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DOpen%2BField"><span>Four large-scale field-aligned <span class="hlt">current</span> systmes in the dayside high-latitude region</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Ohtani, S.; Potemra, T. A.; Newell, P.T.; Zanetti, L. J.; Iijima, T.; Watanabe, M.; Blomberg, L. G.; Elphinstone, R. D.; Murphree, J. S.; Yamauchi, M.</p> <p>1995-01-01</p> <p>A system of four <span class="hlt">current</span> <span class="hlt">sheets</span> of large-scale field-aligned <span class="hlt">currents</span> (FACs) was discovered in the data set of simultaneous Viking and Defense Meteorological Satellire Program-F7 (DMSP-F7) crossing of the dayside high-latitude region. This paper reports four examples of this system that were observed in the prenoon sector. The flow polarities of FACs are upward, downward, upward, and downward, from equatorward to poleward. The lowest-latitude upward <span class="hlt">current</span> is flowing mostly in the central plasma <span class="hlt">sheet</span> (CPS) precipitation region, often overlapping with the boundary plasma <span class="hlt">sheet</span> (BPS) at its poleward edge, andis interpreted as a region 2 <span class="hlt">current</span>. The pair of downward and upward FACs in the middle of te structure are collocated with structured electron precipitation. The precipitation of high-energy (greater than 1 keV) electrons is more intense in the lower-latitude downward <span class="hlt">current</span> <span class="hlt">sheet</span>. The highest-latitude downward flowing <span class="hlt">current</span> <span class="hlt">sheet</span> is located in a weak, low-energy particle precipitation region, suggesting that this <span class="hlt">current</span> is flowing on open field lines. Simulaneous observations in the postnoon local time sector reveal the standard three-<span class="hlt">sheet</span> structure of FACs, sometimes described as region 2, region 1, and mantle (referred to the midday region O) <span class="hlt">currents</span>. A high correlation was found between the occurrence of the four FAC <span class="hlt">sheet</span> structure and negative interplanetary magnetic field (IMF) B(sub Y). We discuss the FAC structurein terms of three types of convection cells: the merging, viscous, andlobe cells. During strongly negative IMF B(sub Y), two convection reversals exist in the prenoon sector; one is inside the viscous cell, and the other is between the viscous cell and the lobe cell. This structure of convection flow is supported by the Viking electric field and auroral UV image data. Based on the convection pattern, the four FAC <span class="hlt">sheet</span> structure is interpreted as the latitude overlap of midday and morning FAC systems. We suggest that the for-<span class="hlt">current</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28712873','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28712873"><span>The effect of oil sands <span class="hlt">tailings</span> pond sediments on embryo-larval walleye (Sander vitreus).</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Raine, J C; Turcotte, D; Tumber, V; Peru, K M; Wang, Z; Yang, C; Headley, J V; Parrott, J L</p> <p>2017-10-01</p> <p>Walleye (Sander vitreus) are a commercially important North American fish species that inhabit the Athabasca River. This river flows through the Athabasca oil sands where natural sources of bitumen erode from the McMurray formation. Little information is available on responses of walleye embryos to oil sands <span class="hlt">tailings</span> pond sediments in a laboratory setting. The <span class="hlt">current</span> study describes the design and implementation of a daily-renewal bioassay to assess the potential effects of <span class="hlt">tailings</span> pond sediments from the Athabasca oil sands area on walleye development. Developing walleye embryos were exposed to increasing concentrations of two <span class="hlt">tailings</span> pond sediments (collected in the Athabasca oil sands area) until the completion of yolk absorption in control fish. Sediments from the <span class="hlt">tailings</span> pond represent a mixture of polycyclic aromatic hydrocarbons (PAHs) and alkylated PAHs. During the 31 day exposure, the walleye were examined for mortalities, weight, length and developmental abnormalities to provide an initial evaluation of the effects of the oil sands <span class="hlt">tailings</span> pond sediments. Walleye embryo survival differed between the <span class="hlt">tailings</span> pond sediments, and survival decreased with increasing sediment concentration. Alkylated PAH content differed between the two <span class="hlt">tailings</span> pond sediments and lower embryo survival corresponded to higher total and alkylated PAH content. <span class="hlt">Tailings</span> pond sediment-exposed walleye exhibited a delay in development, as well as increased percentages of larvae with heart and yolk sac edema, and cranial and spinal malformations. These abnormalities in development are often associated with PAH and alkylated PAH exposure. This study provides an exposure design that can be used to assess sediment toxicity to early developmental stages of a fish species not commonly tested in the lab, and lays the groundwork for future studies with this and other difficult-to-culture species. These results offer information on the potential effects of <span class="hlt">tailings</span> pond sediments</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/20504035','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/20504035"><span>Orientation determination of interfacial beta-<span class="hlt">sheet</span> structures in situ.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Nguyen, Khoi Tan; King, John Thomas; Chen, Zhan</p> <p>2010-07-01</p> <p>Structural information such as orientations of interfacial proteins and peptides is important for understanding properties and functions of such biological molecules, which play crucial roles in biological applications and processes such as antimicrobial selectivity, membrane protein activity, biocompatibility, and biosensing performance. The alpha-helical and beta-<span class="hlt">sheet</span> structures are the most widely encountered secondary structures in peptides and proteins. In this paper, for the first time, a method to quantify the orientation of the interfacial beta-<span class="hlt">sheet</span> structure using a combined attenuated total reflectance Fourier transformation infrared spectroscopic (ATR-FTIR) and sum frequency generation (SFG) vibrational spectroscopic study was developed. As an illustration of the methodology, the orientation of tachyplesin I, a 17 amino acid peptide with an antiparallel beta-<span class="hlt">sheet</span>, adsorbed to polymer surfaces as well as associated with a lipid bilayer was determined using the regular and chiral SFG spectra, together with polarized ATR-FTIR amide I signals. Both the tilt angle (theta) and the twist angle (psi) of the beta-<span class="hlt">sheet</span> at interfaces are determined. The developed method in this paper can be used to obtain in situ structural information of beta-<span class="hlt">sheet</span> components in complex molecules. The combination of this method and the existing methodology that is <span class="hlt">currently</span> used to investigate alpha-helical structures will greatly broaden the application of optical spectroscopy in physical chemistry, biochemistry, biophysics, and structural biology.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24681363','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24681363"><span>Metal mobilization under alkaline conditions in ash-covered <span class="hlt">tailings</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Lu, Jinmei; Alakangas, Lena; Wanhainen, Christina</p> <p>2014-06-15</p> <p>The aim of this study was to determine element mobilization and accumulation in mill <span class="hlt">tailings</span> under alkaline conditions. The <span class="hlt">tailings</span> were covered with 50 cm of fly ash, and above a sludge layer. The <span class="hlt">tailings</span> were geochemically and mineralogically investigated. Sulfides, such as pyrrhotite, sphalerite and galena along with gangue minerals such as dolomite, calcite, micas, chlorite, epidote, Mn-pyroxene and rhodonite were identified in the unoxidized <span class="hlt">tailings</span>. The dissolution of the fly ash layer resulted in a high pH (close to 12) in the underlying <span class="hlt">tailings</span>. This, together with the presence of organic matter, increased the weathering of the <span class="hlt">tailings</span> and mobilization of elements in the uppermost 47 cm of the <span class="hlt">tailings</span>. All primary minerals were depleted, except quartz and feldspar which were covered by blurry secondary carbonates. Sulfide-associated elements such as Cd, Fe, Pb, S and Zn and silicate-associated elements such as Fe, Mg and Mn were released from the depletion zone and accumulated deeper down in the <span class="hlt">tailings</span> where the pH decreased to circum-neutral. Sequential extraction suggests that Cd, Cu, Fe, Pb, S and Zn were retained deeper down in the <span class="hlt">tailings</span> and were mainly associated with the sulfide phase. Calcium, Cr, K and Ni released from the ash layer were accumulated in the uppermost depletion zone of the <span class="hlt">tailings</span>. Copyright © 2014 Elsevier Ltd. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22333161','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22333161"><span>Recovery of iron from cyanide <span class="hlt">tailings</span> with reduction roasting-water leaching followed by magnetic separation.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhang, Yali; Li, Huaimei; Yu, Xianjin</p> <p>2012-04-30</p> <p>Cyanide <span class="hlt">tailing</span> is a kind of solid waste produced in the process of gold extraction from gold ore. In this paper, recovery of iron from cyanide <span class="hlt">tailings</span> was studied with reduction roasting-water leaching process followed by magnetic separation. After analysis of chemical composition and crystalline phase, the effects of different parameters on recovery of iron were chiefly introduced. Systematic studies indicate that the high recovery rate and grade of magnetic concentrate of iron can be achieved under the following conditions: weight ratios of cyanide <span class="hlt">tailings</span>/activated carbon/sodium carbonate/sodium sulfate, 100:10:3:10; temperature, 50 °C; time, 60 min at the reduction roasting stage; the liquid to solid ratio is 15:1 (ml/g), leaching at 60 °C for 5 min and stirring speed at 20 r/min at water-leaching; exciting <span class="hlt">current</span> is 2A at magnetic separation. The iron grade of magnetic concentrate was 59.11% and the recovery ratio was 75.12%. The mineralography of cyanide <span class="hlt">tailings</span>, roasted product, water-leached sample, magnetic concentrate and magnetic <span class="hlt">tailings</span> were studied by X-ray powder diffraction (XRD) technique. The microstructures of above products except magnetic <span class="hlt">tailings</span> were also analyzed by scanning electron microscope (SEM) and energy disperse spectroscopy (EDS) to help understand the mechanism. Copyright © 2012 Elsevier B.V. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.G43A1033W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.G43A1033W"><span>Combustion of available fossil-fuel resources sufficient to eliminate the Antarctic Ice <span class="hlt">Sheet</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Winkelmann, R.; Levermann, A.; Ridgwell, A.; Caldeira, K.</p> <p>2015-12-01</p> <p>The Antarctic Ice <span class="hlt">Sheet</span> stores water equivalent to 58 meters in global sea-level rise. Here we show in simulations with the Parallel Ice <span class="hlt">Sheet</span> Model that burning the <span class="hlt">currently</span> attainable fossil-fuel resources is sufficient to eliminate the ice <span class="hlt">sheet</span>. With cumulative fossil-fuel emissions of 10 000 GtC, Antarctica is projected to become almost ice-free with an average contribution to sea-level rise exceeding 3 meters per century during the first millennium. Consistent with recent observations and simulations, the West Antarctic Ice <span class="hlt">Sheet</span> becomes unstable with 600 to 800 GtC of additional carbon emissions. Beyond this additional carbon release, the destabilization of ice basins in both West- and East Antarctica results in a threshold-increase in global sea level. Unabated carbon emissions thus threaten the Antarctic Ice <span class="hlt">Sheet</span> in its entirety with associated sea-level rise that far exceeds that of all other possible sources.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19950056510&hterms=disintegration&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Ddisintegration','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19950056510&hterms=disintegration&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Ddisintegration"><span>Geometry of thin liquid <span class="hlt">sheet</span> flows</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Chubb, Donald L.; Calfo, Frederick D.; Mcconley, Marc W.; Mcmaster, Matthew S.; Afjeh, Abdollah A.</p> <p>1994-01-01</p> <p>Incompresible, thin <span class="hlt">sheet</span> flows have been of research interest for many years. Those studies were mainly concerned with the stability of the flow in a surrounding gas. Squire was the first to carry out a linear, invicid stability analysis of <span class="hlt">sheet</span> flow in air and compare the results with experiment. Dombrowski and Fraser did an experimental study of the disintegration of <span class="hlt">sheet</span> flows using several viscous liquids. They also detected the formulation of holes in their <span class="hlt">sheet</span> flows. Hagerty and Shea carried out an inviscid stability analysis and calculated growth rates with experimental values. They compared their calculated growth rates with experimental values. Taylor studied extensively the stability of thin liquid <span class="hlt">sheets</span> both theoretically and experimentally. He showed that thin <span class="hlt">sheets</span> in a vacuum are stable. Brown experimentally investigated thin liquid <span class="hlt">sheet</span> flows as a method of application of thin films. Clark and Dumbrowski carried out second-order stability analysis for invicid <span class="hlt">sheet</span> flows. Lin introduced viscosity into the linear stability analysis of thin <span class="hlt">sheet</span> flows in a vacuum. Mansour and Chigier conducted an experimental study of the breakup of a <span class="hlt">sheet</span> flow surrounded by high-speed air. Lin et al. did a linear stability analysis that included viscosity and a surrounding gas. Rangel and Sirignano carried out both a linear and nonlinear invisid stability analysis that applies for any density ratio between the <span class="hlt">sheet</span> liquid and the surrounding gas. Now there is renewed interest in <span class="hlt">sheet</span> flows because of their possible application as low mass radiating surfaces. The objective of this study is to investigate the fluid dynamics of <span class="hlt">sheet</span> flows that are of interest for a space radiator system. Analytical expressions that govern the <span class="hlt">sheet</span> geometry are compared with experimental results. Since a space radiator will operate in a vacuum, the analysis does not include any drag force on the <span class="hlt">sheet</span> flow.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2012-title37-vol1/pdf/CFR-2012-title37-vol1-sec1-76.pdf','CFR2012'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2012-title37-vol1/pdf/CFR-2012-title37-vol1-sec1-76.pdf"><span>37 CFR 1.76 - Application data <span class="hlt">sheet</span>.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2012&page.go=Go">Code of Federal Regulations, 2012 CFR</a></p> <p></p> <p>2012-07-01</p> <p>... 37 Patents, Trademarks, and Copyrights 1 2012-07-01 2012-07-01 false Application data <span class="hlt">sheet</span>. 1.76... Application data <span class="hlt">sheet</span>. (a) Application data <span class="hlt">sheet</span>. An application data <span class="hlt">sheet</span> is a <span class="hlt">sheet</span> or <span class="hlt">sheets</span>, that may... bibliographic data, arranged in a format specified by the Office. An application data <span class="hlt">sheet</span> must be titled...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28086905','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28086905"><span>Reduction of eddy <span class="hlt">current</span> losses in inductive transmission systems with ferrite <span class="hlt">sheets</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Maaß, Matthias; Griessner, Andreas; Steixner, Viktor; Zierhofer, Clemens</p> <p>2017-01-05</p> <p>Improvements in eddy <span class="hlt">current</span> suppression are necessary to meet the demand for increasing miniaturization of inductively driven transmission systems in industrial and biomedical applications. The high magnetic permeability and the simultaneously low electrical conductivity of ferrite materials make them ideal candidates for shielding metallic surfaces. For systems like cochlear implants the transmission of data as well as energy over an inductive link is conducted within a well-defined parameter set. For these systems, the shielding can be of particular importance if the properties of the link can be preserved. In this work, we investigate the effect of single and double-layered substrates consisting of ferrite and/or copper on the inductance and coupling of planar spiral coils. The examined link systems represent realistic configurations for active implantable systems such as cochlear implants. Experimental measurements are complemented with analytical calculations and finite element simulations, which are in good agreement for all measured parameters. The results are then used to study the transfer efficiency of an inductive link in a series-parallel resonant topology as a function of substrate size, the number of coil turns and coil separation. We find that ferrite <span class="hlt">sheets</span> can be used to shield the system from unwanted metallic surfaces and to retain the inductive link parameters of the unperturbed system, particularly its transfer efficiency. The required size of the ferrite plates is comparable to the size of the coils, which makes the setup suitable for practical implementations. Since the sizes and geometries chosen for the studied inductive links are comparable to those of cochlear implants, our conclusions apply in particular to these systems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19920059387&hterms=FAC&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DFAC','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19920059387&hterms=FAC&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DFAC"><span>Finite geometry effects of field-aligned <span class="hlt">currents</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Fung, Shing F.; Hoffman, R. A.</p> <p>1992-01-01</p> <p>Results are presented of model calculations of the magnetic field produced by finite <span class="hlt">current</span> regions that would be measured by a spaceborne magnetometer. Conditions were examined under which the infinite <span class="hlt">current</span> <span class="hlt">sheet</span> approximation can be applied to the calculation of the field-aligned <span class="hlt">current</span> (FAC) density, using satellite magnetometer data. The accuracy of the three methods used for calculating the <span class="hlt">current</span> <span class="hlt">sheet</span> normal direction with respect to the spacecraft trajectory was assessed. It is shown that the model can be used to obtain the position and the orientation of the spacecraft trajectory through the FAC region.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.C32B..05S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.C32B..05S"><span>The Ice <span class="hlt">Sheet</span> Mass Balance Inter-comparison Exercise</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Shepherd, A.; Ivins, E. R.</p> <p>2015-12-01</p> <p> for the second phase of IMBIE, including the project organisation, the work programme and schedule, the main science goals, and its <span class="hlt">current</span> status, and reviews the recent and historical contributions that the Antarctic and Greenland ice <span class="hlt">sheets</span> have made to global sea level rise.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://files.eric.ed.gov/fulltext/ED363017.pdf','ERIC'); return false;" href="http://files.eric.ed.gov/fulltext/ED363017.pdf"><span>Communication Fact <span class="hlt">Sheet</span>.</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>American Speech-Language-Hearing Association, Rockville, MD.</p> <p></p> <p>This brief fact <span class="hlt">sheet</span> examines key aspects of communication, communication disabilities, and intervention. The fact <span class="hlt">sheet</span> addresses the following questions: the nature of communication; communication disabilities (definitions of hearing impairments and speech and language impairments are given); effects of communication disabilities (factors…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009EGUGA..11.8790H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009EGUGA..11.8790H"><span>Study of elevation changes along a profile crossing the Greenland Ice <span class="hlt">Sheet</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hvidegaard, S. M.; Sandberg, L.</p> <p>2009-04-01</p> <p>In recent years much research has focused on determining how the Greenland Ice <span class="hlt">Sheet</span> is responding to the observed climate changes. There is wide agreement on the fact that the Ice <span class="hlt">Sheet</span> is <span class="hlt">currently</span> loosing mass, and studies have shown that the mass loss is found near the ice edge and that no significant changes are found in the central part of the Ice <span class="hlt">Sheet</span>. As a part of European Space Agency's CryoSat Validation Experiment (CryoVEx) running from 2004 to 2008, the National Space Institute (DTU Space) measured the elevations along a profile crossing the Greenland Ice <span class="hlt">Sheet</span>. The elevation observations were carried out in 2004, 2006 and 2008 using airborne laser altimetry from a Twin Otter aircraft. The observed profile follows the old EGIG line (Expédition Glaciologique au Groenland, measured in the 1950's) situated between 69-71N, heading nearly east-west. This unique dataset gives the opportunity to study elevation changes along the profile crossing the ice <span class="hlt">sheet</span>. With this work, we outline the observed elevation changes from the different zones of the ice <span class="hlt">sheet</span>. We furthermore compare elevation changes based on coincident ICESat and airborne laser altimeter data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5559208','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5559208"><span>Seismic evidence for complex sedimentary control of Greenland Ice <span class="hlt">Sheet</span> flow</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Kulessa, Bernd; Hubbard, Alun L.; Booth, Adam D.; Bougamont, Marion; Dow, Christine F.; Doyle, Samuel H.; Christoffersen, Poul; Lindbäck, Katrin; Pettersson, Rickard; Fitzpatrick, Andrew A. W.; Jones, Glenn A.</p> <p>2017-01-01</p> <p>The land-terminating margin of the Greenland Ice <span class="hlt">Sheet</span> has slowed down in recent decades, although the causes and implications for future ice flow are unclear. Explained originally by a self-regulating mechanism where basal slip reduces as drainage evolves from low to high efficiency, recent numerical modeling invokes a sedimentary control of ice <span class="hlt">sheet</span> flow as an alternative hypothesis. Although both hypotheses can explain the recent slowdown, their respective forecasts of a long-term deceleration versus an acceleration of ice flow are contradictory. We present amplitude-versus-angle seismic data as the first observational test of the alternative hypothesis. We document transient modifications of basal sediment strengths by rapid subglacial drainages of supraglacial lakes, the primary <span class="hlt">current</span> control on summer ice <span class="hlt">sheet</span> flow according to our numerical model. Our observations agree with simulations of initial postdrainage sediment weakening and ice flow accelerations, and subsequent sediment restrengthening and ice flow decelerations, and thus confirm the alternative hypothesis. Although simulated melt season acceleration of ice flow due to weakening of subglacial sediments does not <span class="hlt">currently</span> outweigh winter slowdown forced by self-regulation, they could dominate over the longer term. Subglacial sediments beneath the Greenland Ice <span class="hlt">Sheet</span> must therefore be mapped and characterized, and a sedimentary control of ice flow must be evaluated against competing self-regulation mechanisms. PMID:28835915</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28835915','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28835915"><span>Seismic evidence for complex sedimentary control of Greenland Ice <span class="hlt">Sheet</span> flow.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kulessa, Bernd; Hubbard, Alun L; Booth, Adam D; Bougamont, Marion; Dow, Christine F; Doyle, Samuel H; Christoffersen, Poul; Lindbäck, Katrin; Pettersson, Rickard; Fitzpatrick, Andrew A W; Jones, Glenn A</p> <p>2017-08-01</p> <p>The land-terminating margin of the Greenland Ice <span class="hlt">Sheet</span> has slowed down in recent decades, although the causes and implications for future ice flow are unclear. Explained originally by a self-regulating mechanism where basal slip reduces as drainage evolves from low to high efficiency, recent numerical modeling invokes a sedimentary control of ice <span class="hlt">sheet</span> flow as an alternative hypothesis. Although both hypotheses can explain the recent slowdown, their respective forecasts of a long-term deceleration versus an acceleration of ice flow are contradictory. We present amplitude-versus-angle seismic data as the first observational test of the alternative hypothesis. We document transient modifications of basal sediment strengths by rapid subglacial drainages of supraglacial lakes, the primary <span class="hlt">current</span> control on summer ice <span class="hlt">sheet</span> flow according to our numerical model. Our observations agree with simulations of initial postdrainage sediment weakening and ice flow accelerations, and subsequent sediment restrengthening and ice flow decelerations, and thus confirm the alternative hypothesis. Although simulated melt season acceleration of ice flow due to weakening of subglacial sediments does not <span class="hlt">currently</span> outweigh winter slowdown forced by self-regulation, they could dominate over the longer term. Subglacial sediments beneath the Greenland Ice <span class="hlt">Sheet</span> must therefore be mapped and characterized, and a sedimentary control of ice flow must be evaluated against competing self-regulation mechanisms.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19970022378','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19970022378"><span>Vertical <span class="hlt">Tail</span> Buffeting Alleviation Using Piezoelectric Actuators-Some Results of the Actively Controlled Response of Buffet-Affected <span class="hlt">Tails</span> (ACROBAT) Program</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Moses, Robert W.</p> <p>1997-01-01</p> <p>Buffet is an aeroelastic phenomenon associated with high performance aircraft especially those with twin vertical <span class="hlt">tails</span>. In particular, for the F/A-18 aircraft at high angles of attack, vortices emanating from wing/fuselage leading edge extensions burst, immersing the vertical <span class="hlt">tails</span> in their wake. The resulting buffet loads on the vertical <span class="hlt">tails</span> are a concern from fatigue and inspection points of view. Recently, a 1/6-scale F-18 wind-tunnel model was tested in the Transonic Dynamics Tunnel at the NASA Langley Research Center as part of the Actively Controlled Response Of Buffet Affected <span class="hlt">Tails</span> (ACROBAT) Program to assess the use of active controls in reducing vertical <span class="hlt">tail</span> buffeting. The starboard vertical <span class="hlt">tail</span> was equipped with an active rudder and the port vertical <span class="hlt">tail</span> was equipped with piezoelectric actuators. The tunnel conditions were atmospheric air at Mach 0.10. By using single-input-single-output control laws at gains well below the physical limits of the actuators, the power spectral density of the root strains at the frequency of the first bending mode of the vertical <span class="hlt">tail</span> was reduced by as much as 60 percent up to angles of attack of 37 degrees. Root mean square (RMS) values of root strain were reduced by as much as 19 percent. The results herein illustrate that buffet alleviation of vertical <span class="hlt">tails</span> can be accomplished using simple active control of the rudder or piezoelectric actuators. In fact, as demonstrated herein, a fixed gain single input single output control law that commands piezoelectric actuators may be active throughout the high angle-of-attack maneuver without requiring any changes during the maneuver. Future tests are mentioned for accentuating the international interest in this area of research.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.G52A..06D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.G52A..06D"><span>Polar ice-<span class="hlt">sheet</span> contributions to sea level during past warm periods</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dutton, A.</p> <p>2015-12-01</p> <p> is a challenge that is <span class="hlt">currently</span> hindered by limited field evidence at high latitudes. Finally, I will explore the concept of how increasing the quantity and quality of paleo sea level and ice <span class="hlt">sheet</span> reconstructions can lead to improved quantification of contemporary changes in ice <span class="hlt">sheets</span> and sea level.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li class="active"><span>25</span></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_25 --> <div class="footer-extlink text-muted" style="margin-bottom:1rem; text-align:center;">Some links on this page may take you to non-federal websites. Their policies may differ from this site.</div> </div><!-- container --> <footer><a id="backToTop" href="#top"> </a><nav><a id="backToTop" href="#top"> </a><ul class="links"><a id="backToTop" href="#top"> </a><li><a id="backToTop" href="#top"></a><a href="/sitemap.html">Site Map</a></li> <li><a href="/members/index.html">Members Only</a></li> <li><a href="/website-policies.html">Website Policies</a></li> <li><a href="https://doe.responsibledisclosure.com/hc/en-us" target="_blank">Vulnerability Disclosure Program</a></li> <li><a href="/contact.html">Contact Us</a></li> </ul> <div class="small">Science.gov is maintained by the U.S. Department of Energy's <a href="https://www.osti.gov/" target="_blank">Office of Scientific and Technical Information</a>, in partnership with <a href="https://www.cendi.gov/" target="_blank">CENDI</a>.</div> </nav> </footer> <script type="text/javascript"><!-- // var lastDiv = ""; function showDiv(divName) { // hide last div if (lastDiv) { document.getElementById(lastDiv).className = "hiddenDiv"; } //if value of the box is not nothing and an object with that name exists, then change the class if (divName && document.getElementById(divName)) { document.getElementById(divName).className = "visibleDiv"; lastDiv = divName; } } //--> </script> <script> /** * Function that tracks a click on an outbound link in Google Analytics. * This function takes a valid URL string as an argument, and uses that URL string * as the event label. */ var trackOutboundLink = function(url,collectionCode) { try { h = window.open(url); setTimeout(function() { ga('send', 'event', 'topic-page-click-through', collectionCode, url); }, 1000); } catch(err){} }; </script> <!-- Google Analytics --> <script> (function(i,s,o,g,r,a,m){i['GoogleAnalyticsObject']=r;i[r]=i[r]||function(){ (i[r].q=i[r].q||[]).push(arguments)},i[r].l=1*new Date();a=s.createElement(o), m=s.getElementsByTagName(o)[0];a.async=1;a.src=g;m.parentNode.insertBefore(a,m) })(window,document,'script','//www.google-analytics.com/analytics.js','ga'); ga('create', 'UA-1122789-34', 'auto'); ga('send', 'pageview'); </script> <!-- End Google Analytics --> <script> showDiv('page_1') </script> </body> </html>