Sample records for current sheet filamentation

  1. Coherent current-carrying filaments during nonlinear reconnecting ELMs and VDEs

    NASA Astrophysics Data System (ADS)

    Ebrahimi, Fatima

    2017-10-01

    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 current sheets/layers develop near the edge as a peeling component of ELMs or during vertical displacement events (associated with the scrape-off layer currents - halo currents), can become unstable to nonaxisymmetric 3-D current-sheet instabilities (peeling- or tearing-like) and nonlinearly form edge coherent current-carrying filaments. Time-evolving edge current sheets 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 current via direct numerical calculations of reconnecting emf terms. For the VDEs during disruption, we show that as the plasma is vertically displaced, edge halo current sheet becomes MHD unstable and forms coherent edge current 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.

  2. Filament structure, organization, and dynamics in MreB sheets.

    PubMed

    Popp, David; Narita, Akihiro; Maeda, Kayo; Fujisawa, Tetsuro; Ghoshdastider, Umesh; Iwasa, Mitsusada; Maéda, Yuichiro; Robinson, Robert C

    2010-05-21

    In vivo fluorescence microscopy studies of bacterial cells have shown that the bacterial shape-determining protein and actin homolog, MreB, forms cable-like structures that spiral around the periphery of the cell. The molecular structure of these cables has yet to be established. Here we show by electron microscopy that Thermatoga maritime MreB forms complex, several mum long multilayered sheets consisting of diagonally interwoven filaments in the presence of either ATP or GTP. This architecture, in agreement with recent rheological measurements on MreB cables, may have superior mechanical properties and could be an important feature for maintaining bacterial cell shape. MreB polymers within the sheets appear to be single-stranded helical filaments rather than the linear protofilaments found in the MreB crystal structure. Sheet assembly occurs over a wide range of pH, ionic strength, and temperature. Polymerization kinetics are consistent with a cooperative assembly mechanism requiring only two steps: monomer activation followed by elongation. Steady-state TIRF microscopy studies of MreB suggest filament treadmilling while high pressure small angle x-ray scattering measurements indicate that the stability of MreB polymers is similar to that of F-actin filaments. In the presence of ADP or GDP, long, thin cables formed in which MreB was arranged in parallel as linear protofilaments. This suggests that the bacterial cell may exploit various nucleotides to generate different filament structures within cables for specific MreB-based functions.

  3. Folding of viscous sheets and filaments

    NASA Astrophysics Data System (ADS)

    Skorobogatiy, M.; Mahadevan, L.

    2000-12-01

    We consider the nonlinear folding behavior of a viscous filament or a sheet under the influence of an external force such as gravity. Everyday examples of this phenomenon are provided by the periodic folding of a sheet of honey as it impinges on toast, or the folding of a stream of shampoo as it falls on one's hand. To understand the evolution of a fold, we formulate and solve a free-boundary problem for the phenomenon, give scaling laws for the size of the folds and the frequency with which they are laid out, and verify these experimentally.

  4. THE FREE-FALL TIME OF FINITE SHEETS AND FILAMENTS

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Toala, Jesus A.; Vazquez-Semadeni, Enrique; Gomez, Gilberto C.

    2012-01-10

    Molecular clouds often exhibit filamentary or sheet-like shapes. We compute the free-fall time ({tau}{sub ff}) for finite, uniform, self-gravitating circular sheets and filamentary clouds of small but finite thickness, so that their volume density {rho} can still be defined. We find that, for thin sheets, the free-fall time is larger than that of a uniform sphere with the same volume density by a factor proportional to {radical}A, where the aspect ratio A is given by A = R/h, R being the sheet's radius and h is its thickness. For filamentary clouds, the aspect ratio is defined as A=L/R, where Lmore » is the filament's half-length and R is its (small) radius, and the modification factor is more complicated, although in the limit of large A it again reduces to nearly {radical}A. We propose that our result for filamentary shapes naturally explains the ubiquitous configuration of clumps fed by filaments observed in the densest structures of molecular clouds. Also, the longer free-fall times for non-spherical geometries in general may contribute toward partially alleviating the 'star formation conundrum', namely, the star formation rate in the Galaxy appears to be proceeding in a timescale much larger than the total molecular mass in the Galaxy divided by its typical free-fall time. If molecular clouds are in general formed by thin sheets and long filaments, then their relevant free-fall time may have been systematically underestimated, possibly by factors of up to one order of magnitude.« less

  5. ER sheet persistence is coupled to myosin 1c-regulated dynamic actin filament arrays.

    PubMed

    Joensuu, Merja; Belevich, Ilya; Rämö, Olli; Nevzorov, Ilya; Vihinen, Helena; Puhka, Maija; Witkos, Tomasz M; Lowe, Martin; Vartiainen, Maria K; Jokitalo, Eija

    2014-04-01

    The endoplasmic reticulum (ER) comprises a dynamic three-dimensional (3D) network with diverse structural and functional domains. Proper ER operation requires an intricate balance within and between dynamics, morphology, and functions, but how these processes are coupled in cells has been unclear. Using live-cell imaging and 3D electron microscopy, we identify a specific subset of actin filaments localizing to polygons defined by ER sheets and tubules and describe a role for these actin arrays in ER sheet persistence and, thereby, in maintenance of the characteristic network architecture by showing that actin depolymerization leads to increased sheet fluctuation and transformations and results in small and less abundant sheet remnants and a defective ER network distribution. Furthermore, we identify myosin 1c localizing to the ER-associated actin filament arrays and reveal a novel role for myosin 1c in regulating these actin structures, as myosin 1c manipulations lead to loss of the actin filaments and to similar ER phenotype as observed after actin depolymerization. We propose that ER-associated actin filaments have a role in ER sheet persistence regulation and thus support the maintenance of sheets as a stationary subdomain of the dynamic ER network.

  6. ER sheet persistence is coupled to myosin 1c–regulated dynamic actin filament arrays

    PubMed Central

    Joensuu, Merja; Belevich, Ilya; Rämö, Olli; Nevzorov, Ilya; Vihinen, Helena; Puhka, Maija; Witkos, Tomasz M.; Lowe, Martin; Vartiainen, Maria K.; Jokitalo, Eija

    2014-01-01

    The endoplasmic reticulum (ER) comprises a dynamic three-dimensional (3D) network with diverse structural and functional domains. Proper ER operation requires an intricate balance within and between dynamics, morphology, and functions, but how these processes are coupled in cells has been unclear. Using live-cell imaging and 3D electron microscopy, we identify a specific subset of actin filaments localizing to polygons defined by ER sheets and tubules and describe a role for these actin arrays in ER sheet persistence and, thereby, in maintenance of the characteristic network architecture by showing that actin depolymerization leads to increased sheet fluctuation and transformations and results in small and less abundant sheet remnants and a defective ER network distribution. Furthermore, we identify myosin 1c localizing to the ER-associated actin filament arrays and reveal a novel role for myosin 1c in regulating these actin structures, as myosin 1c manipulations lead to loss of the actin filaments and to similar ER phenotype as observed after actin depolymerization. We propose that ER-associated actin filaments have a role in ER sheet persistence regulation and thus support the maintenance of sheets as a stationary subdomain of the dynamic ER network. PMID:24523293

  7. Fundamental mechanisms of tensile fracture in aluminum sheet undirectionally reinforced with boron filament

    NASA Technical Reports Server (NTRS)

    Herring, H. W.

    1972-01-01

    Results are presented from an experimental study of the tensile-fracture process in aluminum sheet unidirectionally reinforced with boron filament. The tensile strength of the material is severely limited by a noncumulative fracture mechanism which involves the initiation and sustenance of a chain reaction of filament fractures at a relatively low stress level. Matrix fracture follows in a completely ductile manner. The minimum filament stress for initiation of the fracture mechanism is shown to be approximately 1.17 GN/sq m (170 ksi), and appears to be independent of filament diameter, number of filament layers, and the strength of the filament-matrix bond. All the commonly observed features of tensile fracture surfaces are explained in terms of the observed noncumulative fracture mechanism.

  8. Nonlinear evolution of three-dimensional instabilities of thin and thick electron scale current sheets: Plasmoid formation and current filamentation

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Jain, Neeraj; Büchner, Jörg; Max Planck Institute for Solar System Research, Justus-Von-Liebig-Weg-3, Göttingen

    Nonlinear evolution of three dimensional electron shear flow instabilities of an electron current sheet (ECS) is studied using electron-magnetohydrodynamic simulations. The dependence of the evolution on current sheet thickness is examined. For thin current sheets (half thickness =d{sub e}=c/ω{sub pe}), tearing mode instability dominates. In its nonlinear evolution, it leads to the formation of oblique current 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 current sheetsmore » (half thickness ∼5 d{sub e}), both tearing and non-tearing modes grow. Due to the non-tearing mode, current sheet 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 current sheets 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

  9. Triggering of explosive reconnection in a thick current sheet via current sheet compression: Less current sheet thinning, more temperature anisotropy

    NASA Astrophysics Data System (ADS)

    Shimizu, K.; Shinohara, I.; Fujimoto, M.

    2016-12-01

    Two-dimensional kinetic simulations of compression of thick current sheets are performed to see how it can lead to triggering of explosive magnetic reconnection. The current sheet 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 current sheet width. When the lobe magnetic field is amplified by a factor of 2, the plasma temperature anisotropy inside the current sheet reaches 2 but the current sheet thickness is reduced only by 1/sqrt(2). If a current sheet 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 current sheet 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 current sheets compares with the instabilities in the plane orthogonal to the reconnecting field.

  10. Filamentary structures in dense plasma focus: Current filaments or vortex filaments?

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Soto, Leopoldo, E-mail: lsoto@cchen.cl; Pavez, Cristian; Moreno, José

    2014-07-15

    Recent observations of an azimuthally distributed array of sub-millimeter size sources of fusion protons and correlation between extreme ultraviolet (XUV) images of filaments with neutron yield in PF-1000 plasma focus have re-kindled interest in their significance. These filaments have been described variously in literature as current filaments and vortex filaments, with very little experimental evidence in support of either nomenclature. This paper provides, for the first time, experimental observations of filaments on a table-top plasma focus device using three techniques: framing photography of visible self-luminosity from the plasma, schlieren photography, and interferometry. Quantitative evaluation of density profile of filaments frommore » interferometry reveals that their radius closely agrees with the collision-less ion skin depth. This is a signature of relaxed state of a Hall fluid, which has significant mass flow with equipartition between kinetic and magnetic energy, supporting the “vortex filament” description. This interpretation is consistent with empirical evidence of an efficient energy concentration mechanism inferred from nuclear reaction yields.« less

  11. Calculations of axisymmetric vortex sheet roll-up using a panel and a filament model

    NASA Technical Reports Server (NTRS)

    Kantelis, J. P.; Widnall, S. E.

    1986-01-01

    A method for calculating the self-induced motion of a vortex sheet using discrete vortex elements is presented. Vortex panels and vortex filaments are used to simulate two-dimensional and axisymmetric vortex sheet roll-up. A straight forward application using vortex elements to simulate the motion of a disk of vorticity with an elliptic circulation distribution yields unsatisfactroy results where the vortex elements move in a chaotic manner. The difficulty is assumed to be due to the inability of a finite number of discrete vortex elements to model the singularity at the sheet edge and due to large velocity calculation errors which result from uneven sheet stretching. A model of the inner portion of the spiral is introduced to eliminate the difficulty with the sheet edge singularity. The model replaces the outermost portion of the sheet with a single vortex of equivalent circulation and a number of higher order terms which account for the asymmetry of the spiral. The resulting discrete vortex model is applied to both two-dimensional and axisymmetric sheets. The two-dimensional roll-up is compared to the solution for a semi-infinite sheet with good results.

  12. Light sources based on semiconductor current filaments

    DOEpatents

    Zutavern, Fred J.; Loubriel, Guillermo M.; Buttram, Malcolm T.; Mar, Alan; Helgeson, Wesley D.; O'Malley, Martin W.; Hjalmarson, Harold P.; Baca, Albert G.; Chow, Weng W.; Vawter, G. Allen

    2003-01-01

    The present invention provides a new type of semiconductor light source that can produce a high peak power output and is not injection, e-beam, or optically pumped. The present invention is capable of producing high quality coherent or incoherent optical emission. The present invention is based on current filaments, unlike conventional semiconductor lasers that are based on p-n junctions. The present invention provides a light source formed by an electron-hole plasma inside a current filament. The electron-hole plasma can be several hundred microns in diameter and several centimeters long. A current filament can be initiated optically or with an e-beam, but can be pumped electrically across a large insulating region. A current filament can be produced in high gain photoconductive semiconductor switches. The light source provided by the present invention has a potentially large volume and therefore a potentially large energy per pulse or peak power available from a single (coherent) semiconductor laser. Like other semiconductor lasers, these light sources will emit radiation at the wavelength near the bandgap energy (for GaAs 875 nm or near infra red). Immediate potential applications of the present invention include high energy, short pulse, compact, low cost lasers and other incoherent light sources.

  13. Simulation of current-filament dynamics and relaxation in the Pegasus Spherical Tokamak

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    O'Bryan, J. B.; Sovinec, C. R.; Bird, T. M.

    Nonlinear numerical computation is used to investigate the relaxation of non-axisymmetric current-channels from washer-gun plasma sources into 'tokamak-like' plasmas in the Pegasus toroidal experiment [Eidietis et al. J. Fusion Energy 26, 43 (2007)]. Resistive MHD simulations with the NIMROD code [Sovinec et al. Phys. Plasmas 10(5), 1727-1732 (2003)] utilize ohmic heating, temperature-dependent resistivity, and anisotropic, temperature-dependent thermal conduction corrected for regions of low magnetization to reproduce critical transport effects. Adjacent passes of the simulated current-channel attract and generate strong reversed current sheets that suggest magnetic reconnection. With sufficient injected current, adjacent passes merge periodically, releasing axisymmetric current rings from themore » driven channel. The current rings have not been previously observed in helicity injection for spherical tokamaks, and as such, provide a new phenomenological understanding for filament relaxation in Pegasus. After large-scale poloidal-field reversal, a hollow current profile and significant poloidal flux amplification accumulate over many reconnection cycles.« less

  14. Collisionless current sheet equilibria

    NASA Astrophysics Data System (ADS)

    Neukirch, T.; Wilson, F.; Allanson, O.

    2018-01-01

    Current sheets 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 current sheets 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 current sheets with particular properties, for example for cases where the current density is parallel to the magnetic field (force-free current sheets). 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.

  15. Ohm's law for a current sheet

    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.

  16. 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

  17. 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.

  18. 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.

  19. Fundamental Mechanisms of Tensile Fracture in Aluminum Sheet Unidirectionally Reinforced with Boron Filament. Ph.D. Thesis - Virginia Polytechnic Inst.

    NASA Technical Reports Server (NTRS)

    Herring, H. W.

    1971-01-01

    Results are presented from an experimental research effort to gain a more complete understanding of the physics of tensile fracture in unidirectionally reinforced B-Al composite sheet. By varying the degree of filament degradation resulting from fabrication, composite specimens were produced which failed in tension by the cumulative mode, the noncumulative mode, or by any desired combination of the two modes. Radiographic and acoustic emission techniques were combined to identify and physically describe a previously unrecognized fundamental fracture mechanism which was responsible for the noncumulative mode. The tensile strength of the composite was found to be severely limited by the noncumulative mechanism which involved the initiation and sustenance of a chain reaction of filament fractures at a relatively low stress level followed by ductile fracture of the matrix. The minimum average filament stress required for initiation of the fracture mechanism was shown to be approximately 170 ksi, and appeared to be independent of filament diameter, number of filament layers, and the identity of the matrix alloy.

  20. Fluctuation dynamics in reconnecting current sheets

    NASA Astrophysics Data System (ADS)

    von Stechow, Adrian; Grulke, Olaf; Ji, Hantao; Yamada, Masaaki; Klinger, Thomas

    2015-11-01

    During magnetic reconnection, a highly localized current sheet 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 current sheet. 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 current sheet in the electron drift direction. They are intrinsic to the localized current sheet 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 current sheet.

  1. 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

  2. A comparison of coronal and interplanetary current sheet inclinations

    NASA Technical Reports Server (NTRS)

    Behannon, K. W.; Burlaga, L. F.; Hundhausen, A. J.

    1983-01-01

    The HAO white light K-coronameter observations show that the inclination of the heliospheric current sheet 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 current sheet 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) current sheet and another in which a nearly horizontal, near equatorial current sheet is indicated. For the crossings of the vertical current sheet, a variance analysis based on hour averages of the magnetic field data gave a minimum variance direction consistent with a steep inclination. The horizontal current sheet 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 current sheet at 1.4 AU. However, variance analysis of individual current sheet crossings in this interval using 1.92 see averages did not give minimum variance directions consistent with a horizontal current sheet.

  3. On ballooning instability in current sheets

    NASA Astrophysics Data System (ADS)

    Leonovich, Anatoliy; Kozlov, Daniil

    2015-06-01

    The problem of instability of the magnetotail current sheet to azimuthally small-scale Alfvén and slow magnetosonic (SMS) waves is solved. The solutions describe unstable oscillations in the presence of a current sheet 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 current sheet. 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 current sheet. The structure of azimuthally small-scale Alfvén waves across magnetic shells is determined.

  4. 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.

  5. THEMIS two‐point measurements of the cross‐tail current density: A thick bifurcated current sheet in the near‐Earth plasma sheet

    PubMed Central

    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

  6. Plasmoid Instability in Forming Current Sheets

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Comisso, L.; Lingam, M.; Huang, Y. -M.

    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 current sheets, 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 current sheets that evolve over time. Our method relies on a principle of least time that enables us to determine the properties of the reconnecting current sheet (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 current sheet 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 current sheet 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

  7. Plasmoid Instability in Forming Current Sheets

    DOE PAGES

    Comisso, L.; Lingam, M.; Huang, Y. -M.; ...

    2017-11-28

    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 current sheets, 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 current sheets that evolve over time. Our method relies on a principle of least time that enables us to determine the properties of the reconnecting current sheet (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 current sheet 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 current sheet 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

  8. THE EVOLUTION OF THE ELECTRIC CURRENT DURING THE FORMATION AND ERUPTION OF ACTIVE-REGION FILAMENTS

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wang, Jincheng; Yan, Xiaoli; Qu, Zhongquan

    We present a comprehensive study of the electric current related to the formation and eruption of active region filaments in NOAA AR 11884. The vertical current on the solar surface was investigated by using vector magnetograms (VMs) observed by HMI on board the Solar Dynamics Observatory. To obtain the electric current along the filament's axis, we reconstructed the magnetic fields above the photosphere by using nonlinear force-free field extrapolation based on photospheric VMs. Spatio-temporal evolutions of the vertical current on the photospheric surface and the horizontal current along the filament's axis were studied during the long-term evolution and eruption-related period,more » respectively. The results show that the vertical currents of the entire active region behaved with a decreasing trend and the magnetic fields also kept decreasing during the long-term evolution. For the eruption-related evolution, the mean transverse field strengths decreased before two eruptions and increased sharply after two eruptions in the vicinity of the polarity inversion lines underneath the filament. The related vertical current showed different behaviors in two of the eruptions. On the other hand, a very interesting feature was found: opposite horizontal currents with respect to the current of the filament's axis appeared and increased under the filament before the eruptions and disappeared after the eruptions. We suggest that these opposite currents were carried by the new flux emerging from the photosphere bottom and might be the trigger mechanism for these filament eruptions.« less

  9. 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.

  10. The Spin and Orientation of Dark Matter Halos Within Cosmic Filaments

    NASA Astrophysics Data System (ADS)

    Zhang, Youcai; Yang, Xiaohu; Faltenbacher, Andreas; Springel, Volker; Lin, Weipeng; Wang, Huiyuan

    2009-11-01

    Clusters, filaments, sheets, and voids are the building blocks of the cosmic web. Forming dark matter halos respond to these different large-scale environments, and this in turn affects the properties of galaxies hosted by the halos. It is therefore important to understand the systematic correlations of halo properties with the morphology of the cosmic web, as this informs both about galaxy formation physics and possible systematics of weak lensing studies. In this study, we present and compare two distinct algorithms for finding cosmic filaments and sheets, a task which is far less well established than the identification of dark matter halos or voids. One method is based on the smoothed dark matter density field and the other uses the halo distributions directly. We apply both techniques to one high-resolution N-body simulation and reconstruct the filamentary/sheet like network of the dark matter density field. We focus on investigating the properties of the dark matter halos inside these structures, in particular, on the directions of their spins and the orientation of their shapes with respect to the directions of the filaments and sheets. We find that both the spin and the major axes of filament halos with masses lsim1013 h -1 M sun are preferentially aligned with the direction of the filaments. The spins and major axes of halos in sheets tend to lie parallel to the sheets. There is an opposite mass dependence of the alignment strength for the spin (negative) and major (positive) axes, i.e. with increasing halo mass the major axis tends to be more strongly aligned with the direction of the filament, whereas the alignment between halo spin and filament becomes weaker with increasing halo mass. The alignment strength as a function of the distance to the most massive node halo indicates that there is a transit large-scale environment impact: from the two-dimensional collapse phase of the filament to the three-dimensional collapse phase of the cluster/node halo at

  11. Effects of electron pressure anisotropy on current sheet configuration

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Artemyev, A. V., E-mail: aartemyev@igpp.ucla.edu; Angelopoulos, V.; Runov, A.

    2016-09-15

    Recent spacecraft observations in the Earth's magnetosphere have demonstrated that the magnetotail current sheet can be supported by currents of anisotropic electron population. Strong electron currents are responsible for the formation of very thin (intense) current sheets playing the crucial role in stability of the Earth's magnetotail. We explore the properties of such thin current sheets 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 current sheet supported by currents of anisotropic electrons embedded in an ion-dominated current sheet. Current density profiles in our model agree well with THEMIS observations in the Earth's magnetotail.« less

  12. THE DYNAMICAL GENERATION OF CURRENT SHEETS IN ASTROPHYSICAL PLASMA TURBULENCE

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Howes, Gregory G.

    2016-08-20

    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 current sheets, at small scales, and the locations of these current sheets appear to be associated with enhanced rates of dissipation of the turbulent energy. Therefore, illuminating the origin and nature of these current sheets 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 current sheets in plasma turbulence. Furthermore, we conceptually explain this current sheet development in terms of the nonlinear dynamics of Alfvén wave collisions, showing that these current sheets arise through constructive interference among the initial Alfvén waves and nonlinearly generated modes. The properties of current sheets generated by strong Alfvén wave collisions are compared to published observations of current sheets in the Earth's magnetosheath and the solar wind, and the nature of these current sheets leads to the expectation that Landau damping of the constituent Alfvén waves plays a dominant role in the damping of turbulently generated current sheets.« less

  13. 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.

  14. Kinetic Studies of Thin Current Sheets at Magnetosheath Jets

    NASA Astrophysics Data System (ADS)

    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.

    2017-12-01

    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 currents 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 current regions inside the MSH downstream of the quasi-parallel shock. In both cases the shape of the current region is in the form of a sheet, however they show internal 3D structure on the scale of the spacecraft separation (15 and 20 km, respectively). Both current sheets have a normal magnetic field component different from zero indicating that the regions at the different sides of the current sheets are magnetically connected. Both current sheets are boundaries between two different plasma regions. Furthermore, both current sheets are observed at MSH jets. These jets are characterized by localized dynamic pressure being larger than the solar wind dynamic pressure. One current sheet does not seem to be reconnecting while the other shows reconnection signatures. Inside the non-reconnecting current sheet 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 current sheet 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 current sheet also shows signs of thermalization and electron acceleration processes that are

  15. 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.

  16. Disruption of current filaments and isotropization of magnetic field in counter-streaming plasmas

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Fiuza, Frederico

    We study the stability of current filaments produced by the Weibel, or current filamentation, instability in weakly magnetized counter-streaming plasmas. It is shown that a resonance exists between the current-carrying ions and a longitudinal drift-kink mode that strongly deforms and eventually breaks the current filaments. Analytical estimates of the wavelength, growth rate and saturation level of the resonant mode are derived and validated by three-dimensional particle-in-cell simulations. Furthermore, self-consistent simulations of counter-streaming plasmas indicate that this drift-kink mode is dominant in the slow down of the flows and in the isotropization of the magnetic field, playing an important role inmore » the formation of collision less shocks.« less

  17. Current-sheet formation in two-dimensional coronal fields

    NASA Astrophysics Data System (ADS)

    Billinghurst, M. N.; Craig, I. J. D.; Sneyd, A. D.

    1993-11-01

    The formation of current sheets by shearing motions in line-tied twin-lobed fields is examined. A general analytic argument shows that current sheets 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 current sheets 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 current 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 currents - and strong resistive dissipation - along field lines close to the bounding fieldline.

  18. Dynamo-driven plasmoid formation from a current-sheet instability

    DOE PAGES

    Ebrahimi, F.

    2016-12-15

    Axisymmetric current-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 current sheets are formed from the oppositely directed field lines in the injector region (primary reconnecting current sheet), and the poloidal flux compression near the plasma edge (edge current sheet). We first find that nonaxisymmetric fluctuations arising from the current-sheet 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 current sheet. 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 current sheet 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

  19. Current Sheet Properties and Dynamics During Sympathetic Breakout Eruptions

    NASA Astrophysics Data System (ADS)

    Lynch, B. J.; Edmondson, J. K.

    2013-12-01

    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 current sheet tearing and track the magnetic island formation and evolution during periods of reconnection. The magnetic breakout eruption scenario forms an overlying 'breakout' current sheet 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 current sheet 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 current sheets and compare the properties of the field and plasma inflows into the current sheets and the reconnection jet outflows into the flare loops and flux rope ejecta.

  20. Continuous development of current sheets near and away from magnetic nulls

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kumar, Sanjay; Bhattacharyya, R.

    2016-04-15

    The presented computations compare the strength of current sheets which develop near and away from the magnetic nulls. To ensure the spontaneous generation of current sheets, the computations are performed congruently with Parker's magnetostatic theorem. The simulations evince current sheets 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 current density with numerical resolution, for these different types of current sheets. The results document current sheets near two dimensional magnetic nulls to have larger strength while exhibiting a stronger scalingmore » than the current sheets 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 current sheet is important for energetics of the subsequent reconnection.« less

  1. High Current, Multi-Filament Photoconductive Semiconductor Switching

    DTIC Science & Technology

    2011-06-01

    linear PCSS triggered with a 100 fs laser pulse . Figure 1. A generic photoconductive semiconductor switch rapidly discharges a charged capacitor...switching is the most critical challenge remaining for photoconductive semiconductor switch (PCSS) applications in Pulsed Power. Many authors have...isolation and control, pulsed or DC charging, and long device lifetime, provided the current per filament is limited to 20-30A for short pulse (10

  2. Criticality and turbulence in a resistive magnetohydrodynamic current sheet

    NASA Astrophysics Data System (ADS)

    Klimas, Alexander J.; Uritsky, Vadim M.

    2017-02-01

    Scaling properties of a two-dimensional (2d) plasma physical current-sheet simulation model involving a full set of magnetohydrodynamic (MHD) equations with current-dependent resistivity are investigated. The current sheet 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 current sheet; the transport of magnetic flux from boundaries to current sheet 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 current sheet (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 current sheets which occur ubiquitously in astrophysical and space plasmas.

  3. Criticality and turbulence in a resistive magnetohydrodynamic current sheet.

    PubMed

    Klimas, Alexander J; Uritsky, Vadim M

    2017-02-01

    Scaling properties of a two-dimensional (2d) plasma physical current-sheet simulation model involving a full set of magnetohydrodynamic (MHD) equations with current-dependent resistivity are investigated. The current sheet 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 current sheet; the transport of magnetic flux from boundaries to current sheet 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 current sheet (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 current sheets which occur ubiquitously in astrophysical and space plasmas.

  4. In situ Observations of Heliospheric Current Sheets Evolution

    NASA Astrophysics Data System (ADS)

    Liu, Yong; Peng, Jun; Huang, Jia; Klecker, Berndt

    2017-04-01

    We investigate the Heliospheric current sheet 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 current sheets 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 current sheets 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 current sheet more accurately.

  5. Bursting reconnection of the two co-rotating current loops

    NASA Astrophysics Data System (ADS)

    Bulanov, Sergei; Sokolov, Igor; Sakai, Jun-Ichi

    2000-10-01

    Two parallel plasma filaments carrying electric current (current loops) are considered. The Ampere force induces the filaments' coalescence, which is accompanied by the reconnection of the poloidal magnetic field. Initially the loops rotate along the axii of symmetry. Each of the two loops would be in equilibrium in the absence of the other one. The dynamics of the reconnection is numerically simulated using high-resolution numerical scheme for low-resistive magneto-hydrodynamics. The results of numerical simulation are presented in the form of computer movies. The results show that the rotation strongly modifies the reconnection process, resulting in quasi-periodic (bursting) appearance and disappearance of a current sheet. Fast sliding motion of the plasma along the current sheet is a significant element of the complicated structure of reconnection (current-vortex sheet). The magnetic surfaces in the overal flow are strongly rippled by slow magnetosonic perturbations, so that the specific spiral structures form. This should result in the particle transport enhancement.

  6. Radiation from a current filament driven by a traveling wave

    NASA Technical Reports Server (NTRS)

    Levine, D. M.; Meneghini, R.

    1976-01-01

    Solutions are presented for the electromagnetic fields radiated by an arbitrarily oriented current filament located above a perfectly conducting ground plane and excited by a traveling current wave. Both an approximate solution, valid in the fraunhofer region of the filament and predicting the radiation terms in the fields, and an exact solution, which predicts both near and far field components of the electromagnetic fields, are presented. Both solutions apply to current waveforms which propagate along the channel but are valid regardless of the actual waveshape. The exact solution is valid only for waves which propagate at the speed of light, and the approximate solution is formulated for arbitrary velocity of propagation. The spectrum-magnitude of the fourier transform-of the radiated fields is computed by assuming a compound exponential model for the current waveform. The effects of channel orientation and length, as well as velocity of propagation of the current waveform and location of the observer, are discussed. It is shown that both velocity of propagation and an effective channel length are important in determining the shape of the spectrum.

  7. Observational support for the current sheet catastrophe model of substorm current disruption

    NASA Technical Reports Server (NTRS)

    Burkhart, G. R.; Lopez, R. E.; Dusenbery, P. B.; Speiser, T. W.

    1992-01-01

    The principles of the current sheet 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 current sheet disruption events. According to the model proposed here, the root cause of the current 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.

  8. CRISPR system in filamentous fungi: Current achievements and future directions.

    PubMed

    Deng, Huaxiang; Gao, Ruijie; Liao, Xiangru; Cai, Yujie

    2017-09-05

    As eukaryotes, filamentous fungi share many features with humans, and they produce numerous active metabolites, some of which are toxic. Traditional genetic approaches are generally inefficient, but the clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 system that has been widely used for basic research on bacteria, mammals and plants offers a simple, fast, versatile technology for systemic research on filamentous fungi. In this review, we summarized the current knowledge on Cas9 and its variants, various selective markers used to screen positive clones, different ways used to detect off-target mutations, and different approaches used to express and transform the CRISPR complex. We also highlight several methods that improve the nuclease specificity and efficiency, and discuss current and potential applications of CRISPR/Cas9 system in filamentous fungi for pathogenesis decoding, confirmation of the gene and pathway, bioenergy process, drug discovery, and chromatin dynamics. We also describe how the synthetic gene circuit of CRISPR/Cas9 systems has been used in the response to various complex environmental signals to redirect metabolite flux and ensure continuous metabolite biosynthesis. Copyright © 2017. Published by Elsevier B.V.

  9. A Description of Local Time Asymmetries in the Kronian Current Sheet

    NASA Astrophysics Data System (ADS)

    Nickerson, J. S.; Hansen, K. C.; Gombosi, T. I.

    2012-12-01

    Cassini observations imply that Saturn's magnetospheric current sheet is displaced northward above the rotational equator [C.S. Arridge et al., Warping of Saturn's magnetospheric and magnetotail current sheets, Journal of Geophysical Research, Vol. 113, August 2008]. Arridge et al. show that this hinging of the current sheet 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 current sheet under various solar wind dynamic pressure and solar zenith angle conditions. We show that under reasonable conditions the current sheet 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 current sheet in the dusk sector due to an absence of data but does presume that the current sheet 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 current sheet 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 current sheet under different conditions.

  10. Current disruptions in the near-earth neutral sheet region

    NASA Technical Reports Server (NTRS)

    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.

    1992-01-01

    Current disruption events observed by the Charge Composition Explorer during 1985 and 1986 are examined. Occurrence of current disruption was accompanied by large magnetic field turbulence and frequently with reversal in the sign of the field component normal to the neutral sheet. Current 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 sheet (within about 0.5 RE). Prior to current 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 sheet during the onset of current disruption indicates that the current buildup during the substorm growth phase is associated with enhancement in the particle pressure at the neutral sheet.

  11. Static current-sheet models of quiescent prominences

    NASA Technical Reports Server (NTRS)

    Wu, F.; Low, B. C.

    1986-01-01

    A particular class of theoretical models idealize the prominence to be a discrete flat electric-current sheet suspended vertically in a potential magnetic field. The weight of the prominence is supported by the Lorentz force in the current sheet. These models can be extended to have curved electric-current sheets 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 current in the atmosphere except for the discrete currents in the cold prominence sheet. 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 current 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.

  12. Static current-sheet models of quiescent prominences

    NASA Astrophysics Data System (ADS)

    Wu, F.; Low, B. C.

    1986-12-01

    A particular class of theoretical models idealize the prominence to be a discrete flat electric-current sheet suspended vertically in a potential magnetic field. The weight of the prominence is supported by the Lorentz force in the current sheet. These models can be extended to have curved electric-current sheets 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 current in the atmosphere except for the discrete currents in the cold prominence sheet. 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 current 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.

  13. Phenomenological Model of Current Sheet Canting in Pulsed Electromagnetic Accelerators

    NASA Technical Reports Server (NTRS)

    Markusic, Thomas; Choueiri, E. Y.

    2003-01-01

    The phenomenon of current sheet canting in pulsed electromagnetic accelerators is the departure of the plasma sheet (that carries the current) from a plane that is perpendicular to the electrodes to one that is skewed, or tipped. Review of pulsed electromagnetic accelerator literature reveals that current sheet canting is a ubiquitous phenomenon - occurring in all of the standard accelerator geometries. Developing an understanding of current sheet canting is important because it can detract from the propellant sweeping capabilities of current sheets 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 current front ahead of the initial current conduction channel. In this model, once the current sheet 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 current sheet 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.

  14. Thin current sheets observation by MMS during a near-Earth's magnetotail reconnection event

    NASA Astrophysics Data System (ADS)

    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.

    2017-12-01

    During summer 2017, the four spacecraft of the Magnetospheric Multiscale (MMS) mission traversed the nightside magnetotail current sheet at an apogee of 25 RE. They detected a number of flow reversal events suggestive of the passage of the reconnection current sheet. Due to the mission's unprecedented high-time resolution and spatial separation well below the ion scales, structure of thin current sheets is well resolved both with plasma and field measurements. In this study we examine the detailed structure of thin current sheets during a flow reversal event from tailward flow to Earthward flow, when MMS crossed the center of the current sheet . We investigate the changes in the structure of the thin current sheet relative to the X-point based on multi-point analysis. We determine the motion and strength of the current sheet from curlometer calculations comparing these with currents obtained from the particle data. The observed structures of these current sheets are also compared with simulations.

  15. On spontaneous formation of current sheets: Untwisted magnetic fields

    NASA Astrophysics Data System (ADS)

    Bhattacharyya, R.; Low, B. C.; Smolarkiewicz, P. K.

    2010-11-01

    This is a study of the spontaneous formation of electric current sheets 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, current sheets must form during the evolution despite the geometric simplicity of the prescribed initial fields. In addition to the current sheets associated with magnetic neutral points and field reversal layers, other sheets not associated with such magnetic features are also in evidence. These current sheets 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, current sheet 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

  16. 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

  17. Solar Energetic Particle Transport Near a Heliospheric Current Sheet

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Battarbee, Markus; Dalla, Silvia; Marsh, Mike S., E-mail: mbattarbee@uclan.ac.uk

    2017-02-10

    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 Current Sheet (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 current sheet, 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 current sheet 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 current sheet 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

  18. 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.

  19. A coronal magnetic field model with horizontal volume and sheet currents

    NASA Technical Reports Server (NTRS)

    Zhao, Xuepu; Hoeksema, J. Todd

    1994-01-01

    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 currents outside the source surface or by limiting the interaction to thin current sheets between oppositely directed field regions. Yet observations and numerical Magnetohydrodynamic (MHD) calculations suggest the presence of non-force-free volume currents throughout the corona as well as thin current sheets 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 currents and streamer sheet currents. The present model builds on the magnetostatic equilibria developed by Bogdan and Low and the current-sheet 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 current-current-sheet 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 current-sheet model.

  20. Self-consistent current sheet structures in the quiet-time magnetotail

    NASA Technical Reports Server (NTRS)

    Holland, Daniel L.; Chen, James

    1993-01-01

    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 current and magnetic field satisfy Ampere's law. Force balance between the plasma and magnetic field is satisfied everywhere. The global structure of the current sheet is found to be critically dependent on the source distribution function. The pressure tensor is nondiagonal in the current sheet with anisotropic temperature. A kinetic mechanism is proposed whereby changes in the source distribution results in a thinning of the current sheet.

  1. 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.

  2. Pulsar current sheet C̆erenkov radiation

    NASA Astrophysics Data System (ADS)

    Zhang, Fan

    2018-04-01

    Plasma-filled pulsar magnetospheres contain thin current sheets 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 current sheets, 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.

  3. Coupling between Mercury and its nightside magnetosphere: Cross-tail current sheet asymmetry and substorm current wedge formation

    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

  4. Tearing Instability of a Current Sheet Forming by Sheared Incompressible Flow

    NASA Astrophysics Data System (ADS)

    Tolman, Elizabeth; Loureiro, Nuno; Uzdensky, Dmitri

    2017-10-01

    Sweet-Parker current sheets 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 current sheet as it forms. Such formation can occur as a result of sheared, sub-Alfvénic incompressible flows into and along the sheet. This work presents an analysis of how tearing perturbations behave in a current sheet 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 current sheets to changing current sheets. This material is based upon work supported by the National Science Foundation Graduate Research Fellowship.

  5. Self-Association Process of a Peptide in Solution: From β-Sheet Filaments to Large Embedded Nanotubes

    PubMed Central

    Valéry, C.; Artzner, F.; Robert, B.; Gulick, T.; Keller, G.; Grabielle-Madelmont, C.; Torres, M.-L.; Cherif-Cheikh, R.; Paternostre, M.

    2004-01-01

    Lanreotide is a synthetic octapeptide used in the therapy against acromegaly. When mixed with pure water at 10% (w/w), Lanreotide (acetate salt) forms liquid crystalline and monodisperse nanotubes with a radius of 120 Å. The molecular and supramolecular organization of these structures has been determined in a previous work as relying on the lateral association of 26 β-sheet filaments made of peptide noncovalent dimers, the basic building blocks. The work presented here has been devoted to the corresponding self-association mechanisms, through the characterization of the Lanreotide structures formed in water, as a function of peptide (acetate salt) concentration (from 2% to 70% (w/w)) and temperature (from 15°C to 70°C). The corresponding states of water were also identified and quantified from the thermal behavior of water in the Lanreotide mixtures. At room temperature and below 3% (w/w) Lanreotide acetate in water, soluble aggregates were detected. From 3% to 20% (w/w) long individual and monodisperse nanotubes crystallized in a hexagonal lattice were evidenced. Their molecular and supramolecular organizations are identical to the ones characterized for the 10% (w/w) sample. Heating induces the dissolution of the nanotubes into soluble aggregates of the same structural characteristics as the room temperature ones. The solubilization temperature increases from 20°C to 70°C with the peptide concentration and reaches a plateau between 15% and 25% (w/w) in peptide. These aggregates are proposed to be the β-sheet filaments that self-associate to build the walls of the nanotubes. Above 20% (w/w) of Lanreotide acetate in water, polydisperse embedded nanotubes are formed and the hexagonal lattice is lost. These embedded nanotubes exhibit the same molecular and supramolecular organizations as the individual monodisperse nanotubes formed at lower peptide concentration. The embedded nanotubes do not melt in the range of temperature studied indicating a higher

  6. Spontaneous formation of electric current sheets and the origin of solar flares

    NASA Technical Reports Server (NTRS)

    Low, B. C.; Wolfson, R.

    1988-01-01

    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 current sheets in the interior plasma. In response to specific footpoint displacements, the quadrupolar magnetic field considered is shown to require the formation of multiple electric current sheets as it achieves a force-free state. Some of the current sheets are found to be of finite length, running along separatrix lines of force which separate lobes of magnetic flux. It is suggested that current sheets in the form of infinitely thin magnetic shear layers may be unstable to resistive tearing, a process which may have application to solar flares.

  7. Intrinsic Dawn-Dusk Asymmetry of Magnetotail Thin Current Sheet

    NASA Astrophysics Data System (ADS)

    Lu, S.; Pritchett, P. L.; Angelopoulos, V.; Artemyev, A.

    2017-12-01

    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 current sheet, 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 current sheet region. The simulation is driven by a symmetric and localized (in the y direction) high-latitude electric field, under which the current sheet thins with a decrease of Bz. During the same time, a dawn-dusk asymmetry is formed intrinsically in the thin current sheet, with a smaller Bz, a stronger Hall effect (indicated by the Hall electric field Ez), and a stronger cross-tail current 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.

  8. Keratinocyte cytoskeletal roles in cell sheet engineering

    PubMed Central

    2013-01-01

    Background There is an increasing need to understand cell-cell interactions for cell and tissue engineering purposes, such as optimizing cell sheet constructs, as well as for examining adhesion defect diseases. For cell-sheet engineering, one major obstacle to sheet function is that cell sheets in suspension are fragile and, over time, will contract. While the role of the cytoskeleton in maintaining the structure and adhesion of cells cultured on a rigid substrate is well-characterized, a systematic examination of the role played by different components of the cytoskeleton in regulating cell sheet contraction and cohesion in the absence of a substrate has been lacking. Results In this study, keratinocytes were cultured until confluent and cell sheets were generated using dispase to remove the influence of the substrate. The effects of disrupting actin, microtubules or intermediate filaments on cell-cell interactions were assessed by measuring cell sheet cohesion and contraction. Keratin intermediate filament disruption caused comparable effects on cell sheet cohesion and contraction, when compared to actin or microtubule disruption. Interfering with actomyosin contraction demonstrated that interfering with cell contraction can also diminish cell cohesion. Conclusions All components of the cytoskeleton are involved in maintaining cell sheet cohesion and contraction, although not to the same extent. These findings demonstrate that substrate-free cell sheet biomechanical properties are dependent on the integrity of the cytoskeleton network. PMID:23442760

  9. Spectroscopic Diagnostics of Electric Fields in the Plasma of Current Sheets

    NASA Astrophysics Data System (ADS)

    Gavrilenko, Valeri; Kyrie, Natalya P.; Frank, Anna G.; Oks, Eugene

    2004-11-01

    Spectroscopic measurements of electric fields (EFs) in current sheet plasmas were performed in the CS-3D device. The device is intended to study the evolution of current sheets and the magnetic reconnection phenomena. We used the broadening of spectral lines (SLs) of HeII ions for diagnostics of EFs in the current sheet middle plane, and the broadening of SLs of HeI atoms for detection of EFs in the current sheet peripheral regions. For detection of EFs in current sheet 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 sheet 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.

  10. Nonlinear Dynamics of Non-uniform Current-Vortex Sheets in Magnetohydrodynamic Flows

    NASA Astrophysics Data System (ADS)

    Matsuoka, C.; Nishihara, K.; Sano, T.

    2017-04-01

    A theoretical model is proposed to describe fully nonlinear dynamics of interfaces in two-dimensional MHD flows based on an idea of non-uniform current-vortex sheet. Application of vortex sheet 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 sheet can be extended to MHD flows (current-vortex sheet). Two-dimensional MHD flows are then described only by a one-dimensional Lagrange parameter on the sheet. It is also shown that bulk magnetic field and velocity can be calculated from their values on the sheet. The model is tested by MHD Richtmyer-Meshkov instability with sinusoidal vortex sheet 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 sheet 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 current-vortex sheet. We expect that our model can be applicable to a wide variety of MHD shear flows.

  11. Orientation of cosmic web filaments with respect to the underlying velocity field

    NASA Astrophysics Data System (ADS)

    Tempel, E.; Libeskind, N. I.; Hoffman, Y.; Liivamägi, L. J.; Tamm, A.

    2014-01-01

    The large-scale structure of the Universe is characterized by a web-like structure made of voids, sheets, filaments and knots. The structure of this so-called cosmic web is dictated by the local velocity shear tensor. In particular, the local direction of a filament should be strongly aligned with hat{e}_3, the eigenvector associated with the smallest eigenvalue of the tensor. That conjecture is tested here on the basis of a cosmological simulation. The cosmic web delineated by the halo distribution is probed by a marked point process with interactions (the Bisous model), detecting filaments directly from the halo distribution (P-web). The detected P-web filaments are found to be strongly aligned with the local hat{e}_3: the alignment is within 30° for ˜80 per cent of the elements. This indicates that large-scale filaments defined purely from the distribution of haloes carry more than just morphological information, although the Bisous model does not make any prior assumption on the underlying shear tensor. The P-web filaments are also compared to the structure revealed from the velocity shear tensor itself (V-web). In the densest regions, the P- and V-web filaments overlap well (90 per cent), whereas in lower density regions, the P-web filaments preferentially mark sheets in the V-web.

  12. A low-altitude mechanism for mesoscale dynamics, structure, and current filamentation in the discrete aurora

    NASA Technical Reports Server (NTRS)

    Keskinen, M. J.; Chaturvedi, P. K.; Ossakow, S. L.

    1992-01-01

    The 2D nonlinear evolution of the ionization-driven adiabatic auroral arc instability is studied. We find: (1) the adiabatic auroral arc instability can fully develop on time scales of tens to hundreds of seconds and on spatial scales of tens to hundreds of kilometers; (2) the evolution of this instability leads to nonlinear 'hook-shaped' conductivity structures: (3) this instability can lead to parallel current filamentation over a wide range of scale sizes; and (4) the k-spectra of the density, electric field, and parallel current develop into inverse power laws in agreement with satellite observations. Comparison with mesoscale auroral phenomenology and current filamentation structures is made.

  13. 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.

  14. Spatial Offsets in Flare-CME Current Sheets

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Raymond, John C.; Giordano, Silvio; Ciaravella, Angela, E-mail: jraymond@cfa.harvard.edu

    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 current sheets 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 sheet 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 current sheet embedded in a streamer-like structure.« less

  15. Current Sheet Evolution In The Aftermath Of A CME Event

    NASA Technical Reports Server (NTRS)

    Bemporad, A.; Poletto, G.; Seuss, S. T.; Schwardron, N. A.; Elliott, H. A.; Raymond, J. C.

    2006-01-01

    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 current sheet overlying the arcade. Analysis of the [Fe XVIII] emission allows us to infer the evolution of physical parameters in the current sheet over the entire span of our observations: in particular, we give the temperature versus time in the current sheet 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 current sheet. The SOHO-Ulysses data set provided us with the unique opportunity of analyzing a current sheet 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.

  16. Magnetospheric Reconnection in Modified Current-Sheet Equilibria

    NASA Astrophysics Data System (ADS)

    Newman, D. L.; Goldman, M. V.; Lapenta, G.; Markidis, S.

    2012-10-01

    Particle simulations of magnetic reconnection in Earth's magnetosphere are frequently initialized with a current-carrying Harris equilibrium superposed on a current-free uniform background plasma. The Harris equilibrium satisfies local charge neutrality, but requires that the sheet current 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 currents 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 current sheet. 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.

  17. Current sheet formation in a sheared force-free-magnetic field. [in sun

    NASA Technical Reports Server (NTRS)

    Wolfson, Richard

    1989-01-01

    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 current sheets, despite the absence of such sheets or even of neutral points in the initial state. The calculations discussed here verify the earlier suggestion by Low and Wolfson (1988) that extended current sheets 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 - current sheets - 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 current sheets. Such energy release may be important in solar flares, coronal mass ejections, and other eruptive events.

  18. Evolution of three-dimensional relativistic current sheets and development of self-generated turbulence

    NASA Astrophysics Data System (ADS)

    Takamoto, M.

    2018-05-01

    In this paper, the temporal evolution of three-dimensional relativistic current sheets 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 current sheets in two-dimensional space, and concluded that sufficiently long current sheets 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 current sheet using resistive relativistic magnetohydrodynamic approximation. The results showed that the three-dimensional current sheets 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 sheet is discussed, and it is found that the sheet 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 current sheet in Poynting-dominated plasma.

  19. 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

  20. Elastic deformation and failure in protein filament bundles: Atomistic simulations and coarse-grained modeling.

    PubMed

    Hammond, Nathan A; Kamm, Roger D

    2008-07-01

    The synthetic peptide RAD16-II has shown promise in tissue engineering and drug delivery. It has been studied as a vehicle for cell delivery and controlled release of IGF-1 to repair infarcted cardiac tissue, and as a scaffold to promote capillary formation for an in vitro model of angiogenesis. The structure of RAD16-II is hierarchical, with monomers forming long beta-sheets that pair together to form filaments; filaments form bundles approximately 30-60 nm in diameter; branching networks of filament bundles form macroscopic gels. We investigate the mechanics of shearing between the two beta-sheets constituting one filament, and between cohered filaments of RAD16-II. This shear loading is found in filament bundle bending or in tensile loading of fibers composed of partial-length filaments. Molecular dynamics simulations show that time to failure is a stochastic function of applied shear stress, and that for a given loading time behavior is elastic for sufficiently small shear loads. We propose a coarse-grained model based on Langevin dynamics that matches molecular dynamics results and facilities extending simulations in space and time. The model treats a filament as an elastic string of particles, each having potential energy that is a periodic function of its position relative to the neighboring filament. With insight from these simulations, we discuss strategies for strengthening RAD16-II and similar materials.

  1. Structure and Dynamics of Current Sheets in 3D Magnetic Fields with the X-line

    NASA Astrophysics Data System (ADS)

    Frank, Anna G.; Bogdanov, S. Yu.; Bugrov, S. G.; Markov, V. S.; Dreiden, G. V.; Ostrovskaya, G. V.

    2004-11-01

    Experimental results are presented on the structure of current sheets 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 current sheets and plasma compression were observed in the presence of the longitudinal magnetic field component aligned with the X-line. Plasma density decreased and the sheet thickness increased with an increase of the longitudinal component. We succeeded to reveal formation of the sheets taking unusual shape, namely tilted and asymmetric sheets, in plasmas with the heavy ions. These current sheets were obviously different from the planar sheets formed in 2D magnetic fields, i.e. without longitudinal component. Analysis of typical plasma parameters made it evident that plasma dynamics and current sheet evolution should be treated on the base of the two-fluid approach. Specifically it is necessary to take into account the Hall currents in the plane perpendicular to the X-line, and the dynamic effects resulting from interaction of the Hall currents and the 3D magnetic field. Supported by RFBR, grant 03-02-17282, and ISTC, project 2098.

  2. A filament of energetic particles near the high-latitude dawn magnetopause

    NASA Technical Reports Server (NTRS)

    Lui, A. T. Y.; Williams, D. J.; Mcentire, R. W.; Christon, S. P.; Jacquey, C.; Angelopoulos, V.; Yamamoto, T.; Kokubun, S.; Frank, L. A.; Ackerson, K. L.

    1994-01-01

    The Geotail satelite detected a filament of tailward-streaming energetic particles spatially separated from the boundary layer of energetic particles at the high-latitude dawn magnetopause at a downstream distance of approximately 80 R(sub E) on October 27, 1992. During this event, the composition and charge states of energetic ions at energies above approximately 10 keV show significant intermix of ions from solar wind and ionospheric sources. Detailed analysis leads to the deduction that the filament was moving southward towards the neutral sheet at an average speed of approximately 80 km/s, implying an average duskward electric field of approximately 1 mV/m. Its north-south dimension was approximately 1 R(sub E) and it was associated with an earthward directed field-aligned current of approximately 5 mA/m. The filament was separated from the energetic particle boundary layer straddling the magnetopause by approximately 0.8 R(sub E) and was inferred to be detached from the boundary layer at downstream distance beyond approximately 70 R(sub E) in the distant tail.

  3. 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.

  4. Asymmetry of the Martian Current Sheet in a Multi-fluid MHD Model

    NASA Astrophysics Data System (ADS)

    Panoncillo, S. G.; Egan, H. L.; Dong, C.; Connerney, J. E. P.; Brain, D. A.; Jakosky, B. M.

    2017-12-01

    The solar wind carries interplanetary magnetic field (IMF) lines toward Mars, where they drape around the planet's conducting ionosphere, creating a current sheet behind the planet where the magnetic field has opposite polarity on either side. In its simplest form, the current sheet 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 current sheet 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 current sheet asymmetries. By altering one variable at a time we were able to measure how these variables influence the location of the current sheet. We found that the current sheet 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 current sheet 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

  5. A priori Estimates for 3D Incompressible Current-Vortex Sheets

    NASA Astrophysics Data System (ADS)

    Coulombel, J.-F.; Morando, A.; Secchi, P.; Trebeschi, P.

    2012-04-01

    We consider the free boundary problem for current-vortex sheets in ideal incompressible magneto-hydrodynamics. It is known that current-vortex sheets 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 current-vortex sheets 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.

  6. Interaction of reflected ions with the firehose marginally stable current sheet - Implications for plasma sheet convection

    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.

  7. Current Sheet Formation in a Conical Theta Pinch Faraday Accelerator with Radio-frequency Assisted Discharge

    NASA Technical Reports Server (NTRS)

    Polzin, Kurt A.; Hallock, Ashley K.; Choueiri, Edgar Y.

    2008-01-01

    Data from an inductive conical theta pinch accelerator are presented to gain insight into the process of inductive current sheet 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 current sheet 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 current sheet formation. Indices are defined that describe time-resolved current sheet characteristics, such as the total current owing in the current sheet, the time-integrated total current ('strength'), and current sheet velocity. It is found that for a given electric field strength, maximums in total current, strength, and velocity occur for one particular background pressure. At other pressures, these current sheet 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.

  8. ELECTRIC CURRENT FILAMENTATION AT A NON-POTENTIAL MAGNETIC NULL-POINT DUE TO PRESSURE PERTURBATION

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Jelínek, P.; Karlický, M.; Murawski, K., E-mail: pjelinek@prf.jcu.cz

    2015-10-20

    An increase of electric current densities due to filamentation is an important process in any flare. We show that the pressure perturbation, followed by an entropy wave, triggers such a filamentation in the non-potential magnetic null-point. In the two-dimensional (2D), non-potential magnetic null-point, we generate the entropy wave by a negative or positive pressure pulse that is launched initially. Then, we study its evolution under the influence of the gravity field. We solve the full set of 2D time dependent, ideal magnetohydrodynamic equations numerically, making use of the FLASH code. The negative pulse leads to an entropy wave with amore » plasma density greater than in the ambient atmosphere and thus this wave falls down in the solar atmosphere, attracted by the gravity force. In the case of the positive pressure pulse, the plasma becomes evacuated and the entropy wave propagates upward. However, in both cases, owing to the Rayleigh–Taylor instability, the electric current in a non-potential magnetic null-point is rapidly filamented and at some locations the electric current density is strongly enhanced in comparison to its initial value. Using numerical simulations, we find that entropy waves initiated either by positive or negative pulses result in an increase of electric current densities close to the magnetic null-point and thus the energy accumulated here can be released as nanoflares or even flares.« less

  9. Coronal Current Sheet Evolution in the Aftermath of a CME

    NASA Technical Reports Server (NTRS)

    Bemporad, A.; Poletto, G.; Suess, S. T.; Ko, Y.-K.; Schwadron, N. A.; Elliott, H. A.; Raymond, J. C.

    2005-01-01

    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 current sheet overlying the arcade. Analysis of the [Fe XVIII] emission allows us to infer the evolution of physical parameters in the current sheet over the entire span of our observations: in particular, we give the temperature vs. time in the current sheet 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 current sheet. Both the remote and in situ observations are compared with predictions of theoretical CME models.

  10. 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.

  11. 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('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('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('http://adsabs.harvard.edu/abs/2017AGUFMSM33B2642A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSM33B2642A"><span>The Topology and Properties of Mercury's Tail <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>Al Asad, M.; Johnson, C.; Philpott, L. C.</p> <p>2017-12-01</p> <p>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 <span class="hlt">current</span> <span class="hlt">sheet</span> (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 <span class="hlt">current</span> <span class="hlt">sheet</span> was encountered on 606 orbits allowing the probability of encountering the tail <span class="hlt">current</span> <span class="hlt">sheet</span> 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</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=19830046182&hterms=Electric+current&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3DElectric%2Bcurrent','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19830046182&hterms=Electric+current&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3DElectric%2Bcurrent"><span>Electric <span class="hlt">currents</span> and voltage drops along auroral field lines</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>1983-01-01</p> <p>An assessment is presented of the <span class="hlt">current</span> state of knowledge concerning Birkeland <span class="hlt">currents</span> and the parallel electric field, with discussions focusing on the Birkeland primary region 1 <span class="hlt">sheets</span>, the region 2 <span class="hlt">sheets</span> which parallel them and appear to close in the partial ring <span class="hlt">current</span>, the cusp <span class="hlt">currents</span> (which may be correlated with the interplanetary B(y) component), and the Harang <span class="hlt">filament</span>. The energy required by the parallel electric field and the associated particle acceleration processes appears to be derived from the Birkeland <span class="hlt">currents</span>, for which evidence is adduced from particles, inverted V spectra, rising ion beams and expanded loss cones. Conics may on the other hand signify acceleration by electrostatic ion cyclotron waves associated with beams accelerated by the parallel electric field.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1367324-nonlinear-reconnecting-edge-localized-modes-current-carrying-plasmas','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1367324-nonlinear-reconnecting-edge-localized-modes-current-carrying-plasmas"><span>Nonlinear reconnecting edge localized modes in <span class="hlt">current</span>-carrying plasmas</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Ebrahimi, F.</p> <p>2017-05-22</p> <p>Nonlinear edge localized modes in a tokamak are examined using global three-dimensional resistive magnetohydrodynamics simulations. Coherent <span class="hlt">current</span>-carrying <span class="hlt">filament</span> (ribbon-like) structures wrapped around the torus are nonlinearly formed due to nonaxisymmetric reconnecting <span class="hlt">current</span> <span class="hlt">sheet</span> instabilities, the so-called peeling-like edge localized modes. These fast growing modes saturate by breaking axisymmetric <span class="hlt">current</span> layers isolated near the plasma edge and go through repetitive relaxation cycles by expelling <span class="hlt">current</span> radially outward and relaxing it back. The local bidirectional fluctuation-induced electromotive force (emf) from the edge localized modes, the dynamo action, relaxes the axisymmetric <span class="hlt">current</span> density and forms <span class="hlt">current</span> holes near the edge. Furthermore, the three-dimensionalmore » coherent <span class="hlt">current</span>-carrying <span class="hlt">filament</span> structures (sometimes referred to as 3-D plasmoids) observed here should also have strong implications for solar and astrophysical reconnection.« 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_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/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> <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('https://www.osti.gov/servlets/purl/866656','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/866656"><span>Electron emitting <span class="hlt">filaments</span> for electron discharge devices</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Leung, Ka-Ngo; Pincosy, Philip A.; Ehlers, Kenneth W.</p> <p>1988-01-01</p> <p>Electrons are copiously emitted by a device comprising a loop-shaped <span class="hlt">filament</span> made of lanthanum hexaboride. The <span class="hlt">filament</span> is directly heated by an electrical <span class="hlt">current</span> produced along the <span class="hlt">filament</span> by a power supply connected to the terminal legs of the <span class="hlt">filament</span>. To produce a <span class="hlt">filament</span>, a diamond saw or the like is used to cut a slice from a bar made of lanthanum hexaboride. The diamond saw is then used to cut the slice into the shape of a loop which may be generally rectangular, U-shaped, hairpin-shaped, zigzag-shaped, or generally circular. The <span class="hlt">filaments</span> provide high electron emission at a relatively low operating temperature, such as 1600.degree. C. To achieve uniform heating, the <span class="hlt">filament</span> is formed with a cross section which is tapered between the opposite ends of the <span class="hlt">filament</span> to compensate for non-uniform <span class="hlt">current</span> distribution along the <span class="hlt">filament</span> due to the emission of electrons from the <span class="hlt">filament</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/6969013','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/biblio/6969013"><span>Electron emitting <span class="hlt">filaments</span> for electron discharge devices</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Leung, K.N.; Pincosy, P.A.; Ehlers, K.W.</p> <p>1983-06-10</p> <p>Electrons are copiously emitted by a device comprising a loop-shaped <span class="hlt">filament</span> made of lanthanum hexaboride. The <span class="hlt">filament</span> is directly heated by an electrical <span class="hlt">current</span> produced along the <span class="hlt">filament</span> by a power supply connected to the terminal legs of the <span class="hlt">filament</span>. To produce a <span class="hlt">filament</span>, a diamond saw or the like is used to cut a slice from a bar made of lanthanum hexaboride. The diamond saw is then used to cut the slice into the shape of a loop which may be generally rectangular, U-shaped, hairpin-shaped, zigzag-shaped, or generally circular. The <span class="hlt">filaments</span> provide high electron emission at a relatively low operating temperature, such as 1600/sup 0/C. To achieve uniform heating, the <span class="hlt">filament</span> is formed with a cross section which is tapered between the opposite ends of the <span class="hlt">filament</span> to compensate for nonuniform <span class="hlt">current</span> distribution along the <span class="hlt">filament</span> due to the emission of electrons from the <span class="hlt">filament</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009AGUFMSM52A..07O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009AGUFMSM52A..07O"><span><span class="hlt">CURRENT</span> <span class="hlt">SHEET</span> THINNING AND ENTROPY CONSTRAINTS DURING THE SUBSTORM GROWTH PHASE</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Otto, A.; Hall, F., IV</p> <p>2009-12-01</p> <p>A typical property during the growth phase of geomagnetic substorms is the thinning of the near-Earth <span class="hlt">current</span> <span class="hlt">sheet</span>, most pronounced in the region between 6 and 15 R_E. We propose that the cause for the <span class="hlt">current</span> <span class="hlt">sheet</span> 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 <span class="hlt">current</span> 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 <span class="hlt">current</span> <span class="hlt">sheet</span> evolution during the substorm growth phase.</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/2016ApJ...821..117K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016ApJ...821..117K"><span>Cold Milky Way HI Gas in <span class="hlt">Filaments</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kalberla, P. M. W.; Kerp, J.; Haud, U.; Winkel, B.; Ben Bekhti, N.; Flöer, L.; Lenz, D.</p> <p>2016-04-01</p> <p>We investigate data from the Galactic Effelsberg-Bonn H I Survey, supplemented with data from the third release of the Galactic All Sky Survey (GASS III) observed at Parkes. We explore the all-sky distribution of the local Galactic H I gas with | {v}{{LSR}}| \\lt 25 km s-1 on angular scales of 11‧-16‧. Unsharp masking is applied to extract small-scale features. We find cold <span class="hlt">filaments</span> that are aligned with polarized dust emission and conclude that the cold neutral medium (CNM) is mostly organized in <span class="hlt">sheets</span> that are, because of projection effects, observed as <span class="hlt">filaments</span>. These <span class="hlt">filaments</span> are associated with dust ridges, aligned with the magnetic field measured on the structures by Planck at 353 GHz. The CNM above latitudes | b| \\gt 20^\\circ is described by a log-normal distribution, with a median Doppler temperature TD = 223 K, derived from observed line widths that include turbulent contributions. The median neutral hydrogen (H I) column density is NH I ≃ 1019.1 cm-2. These CNM structures are embedded within a warm neutral medium with NH I ≃ 1020 cm-2. Assuming an average distance of 100 pc, we derive for the CNM <span class="hlt">sheets</span> a thickness of ≲0.3 pc. Adopting a magnetic field strength of Btot = (6.0 ± 1.8) μG, proposed by Heiles & Troland, and assuming that the CNM <span class="hlt">filaments</span> are confined by magnetic pressure, we estimate a thickness of 0.09 pc. Correspondingly, the median volume density is in the range 14 ≲ n ≲ 47 cm-3. The authors thank the Deutsche Forschungsgemeinschaft (DFG) for support under grant numbers KE757/11-1, KE757/7-3, KE757/7-2, KE757/7-1, and BE4823/1-1.</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://hdl.handle.net/2060/19850023782','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19850023782"><span>A panel method study of vortex <span class="hlt">sheets</span> with special emphasis on <span class="hlt">sheets</span> of axisymmetric geometry. 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>Sugioka, I.; Widnall, S. E.</p> <p>1985-01-01</p> <p>The self induced evolution of a vortex <span class="hlt">sheet</span> was simulated by modeling the <span class="hlt">sheet</span> using an integration of discrete elements of vorticity. Replacing small sections of a vortex <span class="hlt">sheet</span> by flat panels of constant vorticity is found to reproduce more accurately the initial conditions for the Lagrangian simulation technique than replacement by point vortices. The flat panel method for the vortex <span class="hlt">sheet</span> was then extended to model axisymmetric vortex <span class="hlt">sheets</span>. The local and far field velocities induced by the axisymmetric panels were obtained using matched asymptotic analysis, and some of the uncertainties involved in other models of the axisymmetric vortex <span class="hlt">sheet</span> have been eliminated. One important result of this analysis is the determination of the proper choice of core size for a circular vortex <span class="hlt">filament</span> which may replace a section of an axisymmetric vortex <span class="hlt">sheet</span>. Roll-up of both two dimensional and axisymmetric vortex <span class="hlt">sheets</span> was computed using the panel methods developed in the report.</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('https://www.osti.gov/servlets/purl/865877','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/865877"><span>Apparatus for melt growth of crystalline semiconductor <span class="hlt">sheets</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Ciszek, Theodore F.; Hurd, Jeffery L.</p> <p>1986-01-01</p> <p>An economical method is presented for forming thin <span class="hlt">sheets</span> of crystalline silicon suitable for use in a photovoltaic conversion cell by solidification from the liquid phase. Two spatially separated, generally coplanar <span class="hlt">filaments</span> wettable by liquid silicon and joined together at the end by a bridge member are immersed in a silicon melt and then slowly withdrawn from the melt so that a silicon crystal is grown between the edge of the bridge and the <span class="hlt">filaments</span>.</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> </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/2017ApPhL.111u3505L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017ApPhL.111u3505L"><span>Correlation analysis between the <span class="hlt">current</span> fluctuation characteristics and the conductive <span class="hlt">filament</span> morphology of HfO2-based memristor</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Li, Yi; Yin, Kang-Sheng; Zhang, Mei-Yun; Cheng, Long; Lu, Ke; Long, Shi-Bing; Zhou, Yaxiong; Wang, Zhuorui; Xue, Kan-Hao; Liu, Ming; Miao, Xiang-Shui</p> <p>2017-11-01</p> <p>Memristors are attracting considerable interest for their prospective applications in nonvolatile memory, neuromorphic computing, and in-memory computing. However, the nature of resistance switching is still under debate, and <span class="hlt">current</span> fluctuation in memristors is one of the critical concerns for stable performance. In this work, random telegraph noise (RTN) as the indication of <span class="hlt">current</span> instabilities in distinct resistance states of the Pt/Ti/HfO2/W memristor is thoroughly investigated. Standard two-level digital-like RTN, multilevel <span class="hlt">current</span> instabilities with non-correlation/correlation defects, and irreversible <span class="hlt">current</span> transitions are observed and analyzed. The dependence of RTN on the resistance and read bias reveals that the <span class="hlt">current</span> fluctuation depends strongly on the morphology and evolution of the conductive <span class="hlt">filament</span> composed of oxygen vacancies. Our results link the <span class="hlt">current</span> fluctuation behaviors to the evolution of the conductive <span class="hlt">filament</span> and will guide continuous optimization of memristive devices.</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('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('https://ntrs.nasa.gov/search.jsp?R=19900047760&hterms=dropout&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Ddropout','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19900047760&hterms=dropout&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Ddropout"><span>Extreme energetic particle decreases near geostationary orbit - A manifestation of <span class="hlt">current</span> diversion within 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>Baker, D. N.; Mcpherron, R. L.</p> <p>1990-01-01</p> <p>A qualitative model of magnetic field reconfiguration as might result from neutral line formation in the central plasma <span class="hlt">sheet</span> 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 <span class="hlt">current</span> is enhanced across the plasma <span class="hlt">sheet</span> both earthward and tailward of a limited region near the neutral line. Such an enhanced cross-tail <span class="hlt">current</span> earthward of the original X line region may contribute to thinning the plasma <span class="hlt">sheet</span> substantially, and this would in turn affect the drift <span class="hlt">currents</span> in that location, thus enhancing the <span class="hlt">current</span> even closer toward the earth. In this way a redistribution and progressive diversion of normal cross-tail <span class="hlt">current</span> throughout much of the inner portion of the plasma <span class="hlt">sheet</span> could occur. The resulting intensified <span class="hlt">current</span>, localized at the inner edge of the plasma <span class="hlt">sheet</span>, 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.</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> <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('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/2013ApPhL.102p3502A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013ApPhL.102p3502A"><span>A simple high-voltage high <span class="hlt">current</span> spark gap with subnanosecond jitter triggered by femtosecond laser <span class="hlt">filamentation</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Arantchouk, L.; Houard, A.; Brelet, Y.; Carbonnel, J.; Larour, J.; André, Y.-B.; Mysyrowicz, A.</p> <p>2013-04-01</p> <p>We describe a simple, sturdy, and reliable spark gap operating with air at atmospheric pressure and able to switch <span class="hlt">currents</span> in excess of 10 kA with sub-nanosecond jitter. The spark gap is remotely triggered by a femtosecond laser <span class="hlt">filament</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JPhCS.907a2024N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JPhCS.907a2024N"><span>Supersonic, subsonic and stationary <span class="hlt">filaments</span> in the plasma focus</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nikulin, V. Ya; Startsev, S. A.; Tsybenko, S. P.</p> <p>2017-10-01</p> <p><span class="hlt">Filaments</span> in the plasma focus were investigated using a model of plasma with the London <span class="hlt">current</span>. These structures involve a forward <span class="hlt">current</span> that flows along the surface of a tangential discontinuity and reverse induction <span class="hlt">currents</span> in the surrounding plasma, including those that flow over the surface of discontinuity, where the magnetic field reverses its direction. Supersonic <span class="hlt">filaments</span> demonstrated the capture of plasma by the London <span class="hlt">current</span>, and in subsonic and stationary <span class="hlt">filaments</span>, the London <span class="hlt">current</span> expelled the plasma.</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://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://www.osti.gov/biblio/5719531','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/biblio/5719531"><span>Method and apparatus for melt growth of crystalline semiconductor <span class="hlt">sheets</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Ciszek, T.F.; Hurd, J.L.</p> <p>1981-02-25</p> <p>An economical method is presented for forming thin <span class="hlt">sheets</span> of crystalline silicon suitable for use in a photovoltaic conversion cell by solidification from the liquid phase. Two spatially separated, generally coplanar <span class="hlt">filaments</span> wettable by liquid silicon and joined together at the end by a bridge member are immersed in a silicon melt and then slowly withdrawn from the melt so that a silicon crystal is grown between the edge of the bridge and the <span class="hlt">filaments</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_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/2060/20150007928','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('https://www.ncbi.nlm.nih.gov/pubmed/27992231','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27992231"><span>From Aβ <span class="hlt">Filament</span> to Fibril: Molecular Mechanism of Surface-Activated Secondary Nucleation from All-Atom MD Simulations.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Schwierz, Nadine; Frost, Christina V; Geissler, Phillip L; Zacharias, Martin</p> <p>2017-02-02</p> <p>Secondary nucleation pathways in which existing amyloid fibrils catalyze the formation of new aggregates and neurotoxic oligomers are of immediate importance for the onset and progression of Alzheimer's disease. Here, we apply extensive all-atom molecular dynamics simulations in explicit water to study surface-activated secondary nucleation pathways at the extended lateral β-<span class="hlt">sheet</span> surface of a preformed Aβ 9-40 <span class="hlt">filament</span>. Calculation of free-energy profiles allows us to determine binding free energies and conformational intermediates for nucleation complexes consisting of 1-4 Aβ peptides. In addition, we combine the free-energy profiles with position-dependent diffusion profiles to extract complementary kinetic information and macroscopic growth rates. Single monomers bind to the β-<span class="hlt">sheet</span> surface in a disordered, hydrophobically collapsed conformation, whereas dimers and larger oligomers can retain a cross-β conformation resembling a more ordered fibril structure. The association processes during secondary nucleation follow a dock/lock mechanism consisting of a fast initial encounter phase (docking) and a slow structural rearrangement phase (locking). The major driving forces for surface-activated secondary nucleation are the release of a large number of hydration water molecules and the formation of hydrophobic interface contacts, the latter being in contrast to the elongation process at <span class="hlt">filament</span> tips, which is dominated by the formation of stable and highly specific interface hydrogen bonds. The calculated binding free energies and the association rates for the attachment of Aβ monomers and oligomers to the extended lateral β-<span class="hlt">sheet</span> surface of the <span class="hlt">filament</span> seed are higher compared to those for elongation at the <span class="hlt">filament</span> tips, indicating that secondary nucleation pathways can become important once a critical concentration of <span class="hlt">filaments</span> has formed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4299214','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4299214"><span>β-Helical architecture of cytoskeletal bactofilin <span class="hlt">filaments</span> revealed by solid-state NMR</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Vasa, Suresh; Lin, Lin; Shi, Chaowei; Habenstein, Birgit; Riedel, Dietmar; Kühn, Juliane; Thanbichler, Martin; Lange, Adam</p> <p>2015-01-01</p> <p>Bactofilins are a widespread class of bacterial <span class="hlt">filament</span>-forming proteins, which serve as cytoskeletal scaffolds in various cellular pathways. They are characterized by a conserved architecture, featuring a central conserved domain (DUF583) that is flanked by variable terminal regions. Here, we present a detailed investigation of bactofilin <span class="hlt">filaments</span> from Caulobacter crescentus by high-resolution solid-state NMR spectroscopy. De novo sequential resonance assignments were obtained for residues Ala39 to Phe137, spanning the conserved DUF583 domain. Analysis of the secondary chemical shifts shows that this core region adopts predominantly β-<span class="hlt">sheet</span> secondary structure. Mutational studies of conserved hydrophobic residues located in the identified β-strand segments suggest that bactofilin folding and polymerization is mediated by an extensive and redundant network of hydrophobic interactions, consistent with the high intrinsic stability of bactofilin polymers. Transmission electron microscopy revealed a propensity of bactofilin to form <span class="hlt">filament</span> bundles as well as <span class="hlt">sheet</span>-like, 2D crystalline assemblies, which may represent the supramolecular arrangement of bactofilin in the native context. Based on the diffraction pattern of these 2D crystalline assemblies, scanning transmission electron microscopy measurements of the mass per length of BacA <span class="hlt">filaments</span>, and the distribution of β-strand segments identified by solid-state NMR, we propose that the DUF583 domain adopts a β-helical architecture, in which 18 β-strand segments are arranged in six consecutive windings of a β-helix. PMID:25550503</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25550503','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25550503"><span>β-Helical architecture of cytoskeletal bactofilin <span class="hlt">filaments</span> revealed by solid-state NMR.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Vasa, Suresh; Lin, Lin; Shi, Chaowei; Habenstein, Birgit; Riedel, Dietmar; Kühn, Juliane; Thanbichler, Martin; Lange, Adam</p> <p>2015-01-13</p> <p>Bactofilins are a widespread class of bacterial <span class="hlt">filament</span>-forming proteins, which serve as cytoskeletal scaffolds in various cellular pathways. They are characterized by a conserved architecture, featuring a central conserved domain (DUF583) that is flanked by variable terminal regions. Here, we present a detailed investigation of bactofilin <span class="hlt">filaments</span> from Caulobacter crescentus by high-resolution solid-state NMR spectroscopy. De novo sequential resonance assignments were obtained for residues Ala39 to Phe137, spanning the conserved DUF583 domain. Analysis of the secondary chemical shifts shows that this core region adopts predominantly β-<span class="hlt">sheet</span> secondary structure. Mutational studies of conserved hydrophobic residues located in the identified β-strand segments suggest that bactofilin folding and polymerization is mediated by an extensive and redundant network of hydrophobic interactions, consistent with the high intrinsic stability of bactofilin polymers. Transmission electron microscopy revealed a propensity of bactofilin to form <span class="hlt">filament</span> bundles as well as <span class="hlt">sheet</span>-like, 2D crystalline assemblies, which may represent the supramolecular arrangement of bactofilin in the native context. Based on the diffraction pattern of these 2D crystalline assemblies, scanning transmission electron microscopy measurements of the mass per length of BacA <span class="hlt">filaments</span>, and the distribution of β-strand segments identified by solid-state NMR, we propose that the DUF583 domain adopts a β-helical architecture, in which 18 β-strand segments are arranged in six consecutive windings of a β-helix.</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.ncbi.nlm.nih.gov/pubmed/25019709','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25019709"><span>Optimal swimming of a <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>Montenegro-Johnson, Thomas D; Lauga, Eric</p> <p>2014-06-01</p> <p>Propulsion at microscopic scales is often achieved through propagating traveling waves along hairlike organelles called flagella. Taylor's two-dimensional swimming <span class="hlt">sheet</span> model is frequently used to provide insight into problems of flagellar propulsion. We derive numerically the large-amplitude wave form of the two-dimensional swimming <span class="hlt">sheet</span> that yields optimum hydrodynamic efficiency: the ratio of the squared swimming speed to the rate-of-working of the <span class="hlt">sheet</span> against the fluid. Using the boundary element method, we show that the optimal wave form is a front-back symmetric regularized cusp that is 25% more efficient than the optimal sine wave. This optimal two-dimensional shape is smooth, qualitatively different from the kinked form of Lighthill's optimal three-dimensional flagellum, not predicted by small-amplitude theory, and different from the smooth circular-arc-like shape of active elastic <span class="hlt">filaments</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19900047779&hterms=disruption&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Ddisruption','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19900047779&hterms=disruption&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Ddisruption"><span>A <span class="hlt">current</span> disruption mechanism in the neutral <span class="hlt">sheet</span> - A possible trigger for 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>1990-01-01</p> <p>A linear analysis is performed to investigate the kinetic cross-field streaming instability in the earth's magnetotail neutral <span class="hlt">sheet</span> region. Numerical solution of the dispersion equation shows that the instability can occur under conditions expected for the neutral <span class="hlt">sheet</span> 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 <span class="hlt">current</span> causing it to continue through the ionosphere to form a substorm <span class="hlt">current</span> 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 <span class="hlt">current</span> <span class="hlt">sheet</span> 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 <span class="hlt">sheet</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29709890','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29709890"><span>Solo and keratin <span class="hlt">filaments</span> regulate epithelial tubule morphology.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Nishimura, Ryosuke; Kato, Kagayaki; Fujiwara, Sachiko; Ohashi, Kazumasa; Mizuno, Kensaku</p> <p>2018-04-28</p> <p>Epithelial tubules, consisting of the epithelial cell <span class="hlt">sheet</span> with a central lumen, are the basic structure of many organs. Mechanical forces play an important role in epithelial tubulogenesis; however, little is known about the mechanisms controlling the mechanical forces during epithelial tubule morphogenesis. Solo (also known as ARHGEF40) is a RhoA-targeting guanine-nucleotide exchange factor that is involved in mechanical force-induced RhoA activation and stress fiber formation. Solo binds to keratin-8/keratin-18 (K8/K18) <span class="hlt">filaments</span>, and this interaction plays a crucial role in mechanotransduction. In this study, we examined the roles of Solo and K8/K18 <span class="hlt">filaments</span> in epithelial tubulogenesis using MDCK cells cultured in 3D collagen gels. Knockdown of either Solo or K18 resulted in rounder tubules with increased lumen size, indicating that Solo and K8/K18 <span class="hlt">filaments</span> play critical roles in forming the elongated morphology of epithelial tubules. Moreover, knockdown of Solo or K18 decreased the level of diphosphorylated myosin light chain (a marker of contractile force) at the luminal and outer surfaces of tubules, suggesting that Solo and K8/K18 <span class="hlt">filaments</span> are involved in the generation of the myosin II-mediated contractile force during epithelial tubule morphogenesis. In addition, K18 <span class="hlt">filaments</span> were normally oriented along the long axis of the tubule, but knockdown of Solo perturbed their orientation. These results suggest that Solo plays crucial roles in forming the elongated morphology of epithelial tubules and in regulating myosin II activity and K18 <span class="hlt">filament</span> organization during epithelial tubule formation.</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://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-tail 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-tail <span class="hlt">current</span> and its diversion to</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://adsabs.harvard.edu/abs/2017AGUFMSM43C2737M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSM43C2737M"><span>Impact of the storm-time plasma <span class="hlt">sheet</span> ion composition on the ring <span class="hlt">current</span> energy density</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mouikis, C.; Kistler, L. M.; Petrinec, S. M.; Fuselier, S. A.; Cohen, I.</p> <p>2017-12-01</p> <p>The adiabatic inward transport of the night-side near-earth ( 6 Re) hot plasma <span class="hlt">sheet</span> is the dominant contributor to the ring <span class="hlt">current</span> pressure during storm times. During storm times, the plasma <span class="hlt">sheet</span> 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 <span class="hlt">sheet</span> 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 <span class="hlt">sheet</span> 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 <span class="hlt">sheet</span>, observed by MMS, is a sufficient source of the O+ in the ring <span class="hlt">current</span>. For this we will compare the phase space density (PSD) of the plasma <span class="hlt">sheet</span> source population and the PSD of the inner magnetosphere at constant magnetic moment values as used in Kistler et al., [2016].</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> <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('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 tail 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 tail 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> </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/22611368-design-klystron-filament-power-supply-control-system-east-lhcd','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22611368-design-klystron-filament-power-supply-control-system-east-lhcd"><span>Design of the klystron <span class="hlt">filament</span> power supply control system for EAST LHCD</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>Wu, Zege; Wang, Mao; Hu, Huaichuan</p> <p></p> <p>A <span class="hlt">filament</span> is a critical component of the klystron used to heat the cathode. There are totally 44 klystrons in experimental advanced superconducting tokamak (EAST) lower hybrid <span class="hlt">current</span> drive (LHCD) systems. All klystron <span class="hlt">filaments</span> are powered by AC power suppliers through isolated transformers. In order to achieve better klystron preheat, a klystron <span class="hlt">filament</span> power supply control system is designed to obtain the automatic control of all <span class="hlt">filament</span> power suppliers. Klystron <span class="hlt">filament</span> <span class="hlt">current</span> is measured by PLC and the interlock between <span class="hlt">filament</span> <span class="hlt">current</span> and klystron high voltage system is also implemented. This design has already been deployed in two LHCD systemsmore » and proves feasible completely.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19960000268','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19960000268"><span>Nonequilibrium transport in superconducting <span class="hlt">filaments</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Arutyunov, K. YU.; Danilova, N. P.; Nikolaeva, A. A.</p> <p>1995-01-01</p> <p>The step-like <span class="hlt">current</span>-voltage characteristics of highly homogeneous single-crystalline tin and indium thin <span class="hlt">filaments</span> has been measured. The length of the samples L approximately 1 cm was much greater than the nonequilibrium quasiparticle relaxation length Lambda. It was found that the activation of a successive i-th voltage step occurs at <span class="hlt">current</span> significantly greater than the one derived with the assumption that the phase slip centers are weakly interacting on a scale L much greater than Lambda. The observation of 'subharmonic' fine structure on the voltage-<span class="hlt">current</span> characteristics of tin <span class="hlt">filaments</span> confirms the hypothesis of the long-range phase slip centers interaction.</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('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4375888','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4375888"><span>Side-binding proteins modulate actin <span class="hlt">filament</span> dynamics</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Crevenna, Alvaro H; Arciniega, Marcelino; Dupont, Aurélie; Mizuno, Naoko; Kowalska, Kaja; Lange, Oliver F; Wedlich-Söldner, Roland; Lamb, Don C</p> <p>2015-01-01</p> <p>Actin <span class="hlt">filament</span> dynamics govern many key physiological processes from cell motility to tissue morphogenesis. A central feature of actin dynamics is the capacity of <span class="hlt">filaments</span> to polymerize and depolymerize at their ends in response to cellular conditions. It is <span class="hlt">currently</span> thought that <span class="hlt">filament</span> kinetics can be described by a single rate constant for each end. In this study, using direct visualization of single actin <span class="hlt">filament</span> elongation, we show that actin polymerization kinetics at both <span class="hlt">filament</span> ends are strongly influenced by the binding of proteins to the lateral <span class="hlt">filament</span> surface. We also show that the pointed-end has a non-elongating state that dominates the observed <span class="hlt">filament</span> kinetic asymmetry. Estimates of flexibility as well as effects on fragmentation and growth suggest that the observed kinetic diversity arises from structural alteration. Tuning elongation kinetics by exploiting the malleability of the <span class="hlt">filament</span> structure may be a ubiquitous mechanism to generate a rich variety of cellular actin dynamics. DOI: http://dx.doi.org/10.7554/eLife.04599.001 PMID:25706231</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27120621','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27120621"><span>Role of Intermediate <span class="hlt">Filaments</span> in Vesicular Traffic.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Margiotta, Azzurra; Bucci, Cecilia</p> <p>2016-04-25</p> <p>Intermediate <span class="hlt">filaments</span> are an important component of the cellular cytoskeleton. The first established role attributed to intermediate <span class="hlt">filaments</span> was the mechanical support to cells. However, it is now clear that intermediate <span class="hlt">filaments</span> have many different roles affecting a variety of other biological functions, such as the organization of microtubules and microfilaments, the regulation of nuclear structure and activity, the control of cell cycle and the regulation of signal transduction pathways. Furthermore, a number of intermediate <span class="hlt">filament</span> proteins have been involved in the acquisition of tumorigenic properties. Over the last years, a strong involvement of intermediate <span class="hlt">filament</span> proteins in the regulation of several aspects of intracellular trafficking has strongly emerged. Here, we review the functions of intermediate <span class="hlt">filaments</span> proteins focusing mainly on the recent knowledge gained from the discovery that intermediate <span class="hlt">filaments</span> associate with key proteins of the vesicular membrane transport machinery. In particular, we analyze the <span class="hlt">current</span> understanding of the contribution of intermediate <span class="hlt">filaments</span> to the endocytic pathway.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PhPl...24h2903Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PhPl...24h2903Z"><span>Electron flat-top distributions and cross-scale wave modulations observed in the <span class="hlt">current</span> <span class="hlt">sheet</span> of geomagnetic tail</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhao, Duo; Fu, Suiyan; Parks, George K.; Sun, Weijie; Zong, Qiugang; Pan, Dongxiao; Wu, Tong</p> <p>2017-08-01</p> <p>We present new observations of electron distributions and the accompanying waves during the <span class="hlt">current</span> <span class="hlt">sheet</span> 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 <span class="hlt">sheet</span> 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 <span class="hlt">current</span> <span class="hlt">sheet</span> 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 <span class="hlt">current</span> <span class="hlt">sheet</span> activities far downstream of the geomagnetic tail.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018ApJS..236...15A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018ApJS..236...15A"><span>Prediction of Solar Eruptions Using <span class="hlt">Filament</span> Metadata</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Aggarwal, Ashna; Schanche, Nicole; Reeves, Katharine K.; Kempton, Dustin; Angryk, Rafal</p> <p>2018-05-01</p> <p>We perform a statistical analysis of erupting and non-erupting solar <span class="hlt">filaments</span> to determine the properties related to the eruption potential. In order to perform this study, we correlate <span class="hlt">filament</span> eruptions documented in the Heliophysics Event Knowledgebase (HEK) with HEK <span class="hlt">filaments</span> that have been grouped together using a spatiotemporal tracking algorithm. The HEK provides metadata about each <span class="hlt">filament</span> instance, including values for length, area, tilt, and chirality. We add additional metadata properties such as the distance from the nearest active region and the magnetic field decay index. We compare trends in the metadata from erupting and non-erupting <span class="hlt">filament</span> tracks to discover which properties present signs of an eruption. We find that a change in <span class="hlt">filament</span> length over time is the most important factor in discriminating between erupting and non-erupting <span class="hlt">filament</span> tracks, with erupting tracks being more likely to have decreasing length. We attempt to find an ensemble of predictive <span class="hlt">filament</span> metadata using a Random Forest Classifier approach, but find the probability of correctly predicting an eruption with the <span class="hlt">current</span> metadata is only slightly better than chance.</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/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 tail, 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 tail 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 tail, 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> <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://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://ntrs.nasa.gov/search.jsp?R=19900036674&hterms=dropout&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Ddropout','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19900036674&hterms=dropout&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Ddropout"><span>Extreme energetic particle decreases near geostationary orbit - A manifestation of <span class="hlt">current</span> diversion within 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>Baker, D. N.; Mcpherron, R. L.</p> <p>1990-01-01</p> <p>A qualitative model of cross-tail <span class="hlt">current</span> flow is considered. It is suggested that when magnetic reconnection begins, the <span class="hlt">current</span> effectively flows across the plasma <span class="hlt">sheet</span> both earthward and tailward of the disruption region near the neutral line. It is shown that an enhanced cross-tail <span class="hlt">current</span> earthward of this region would thin the plasma <span class="hlt">sheet</span> 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.</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> <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> </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('https://ntrs.nasa.gov/search.jsp?R=19870045510&hterms=balance+sheet&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dbalance%2Bsheet','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19870045510&hterms=balance+sheet&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dbalance%2Bsheet"><span>The Giacobini-Zinner magnetotail - Tail configuration and <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>Mccomas, D. J.; Gosling, J. T.; Bame, S. J.; Slavin, J. A.; Smith, E. J.</p> <p>1987-01-01</p> <p>The configuration and properties of the draped Giacobini-Zinner magnetotail and its field-reversing <span class="hlt">current</span> <span class="hlt">sheet</span> 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.</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 tail, 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/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('https://www.osti.gov/biblio/4736408','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/biblio/4736408"><span>METHOD OF MAKING TUNGSTEN <span class="hlt">FILAMENTS</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Frazer, J.W.</p> <p>1962-12-18</p> <p>A method of making tungsten <span class="hlt">filaments</span> is described in which the tungsten is completely free of isotope impurities in the range of masses 234 to 245 for use in mass spectrometers. The <span class="hlt">filament</span> comprises a tantalum core generally less than 1 mil in diameter having a coating of potassium-free tantalum-diffused tungsten molecularly bonded thereto. In the preferred process of manufacture a short, thin tantalum <span class="hlt">filament</span> is first mounted between terminal posts mounted in insulated relation through a backing plate. The tungsten is most conveniently vapor plated onto the tantalum by a tungsten carbonyl vapor decomposition method having a critical step because of the tendency of the tantalum to volatilize at the temperature of operntion of the <span class="hlt">filament</span>. The preferred recipe comprises volatilizing tantalum by resistance henting until the <span class="hlt">current</span> drops by about 40%, cutting the voltage back to build up the tungsten, and then gradually building the temperature back up to balance the rate of tungsten deposition with the rate of tantalum volatilization. (AEC)</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/1998A%26A...339..225V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1998A%26A...339..225V"><span>The effect of delays on <span class="hlt">filament</span> oscillations and stability</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>van den Oord, G. H. J.; Schutgens, N. A. J.; Kuperus, M.</p> <p>1998-11-01</p> <p>We discuss the linear response of a <span class="hlt">filament</span> to perturbations, taking the finite communication time between the <span class="hlt">filament</span> and the photosphere into account. The finite communication time introduces delays in the system. Recently Schutgens (1997ab) investigated the solutions of the delay equation for vertical perturbations. In this paper we expand his analysis by considering also horizontal and coupled oscillations. The latter occur in asymmetric coronal fields. We also discuss the effect of Alfven wave emission on <span class="hlt">filament</span> oscillations and show that wave emission is important for stabilizing <span class="hlt">filaments</span>. We introduce a fairly straightforward method to study the solutions of delay equations as a function of the <span class="hlt">filament</span>-photosphere communication time. A solution can be described by a linear combination of damped harmonic oscillations each characterized by a frequency, a damping/growth time and, accordingly, a quality factor. As a secondary result of our analysis we show that, within the context of line <span class="hlt">current</span> models, Kippenhahn/Schlüter-type <span class="hlt">filament</span> equilibria can never be stable in the horizontal and the vertical direction at the same time but we also demonstrate that Kuperus/Raadu-type equilibria can account for both an inverse or a normal polarity signature. The diagnostic value of our analysis for determining, e.g., the <span class="hlt">filament</span> <span class="hlt">current</span> from observations of oscillating <span class="hlt">filaments</span> is discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29687901','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29687901"><span>Thick <span class="hlt">Filament</span> Protein Network, Functions, and Disease Association.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wang, Li; Geist, Janelle; Grogan, Alyssa; Hu, Li-Yen R; Kontrogianni-Konstantopoulos, Aikaterini</p> <p>2018-03-13</p> <p>Sarcomeres consist of highly ordered arrays of thick myosin and thin actin <span class="hlt">filaments</span> along with accessory proteins. Thick <span class="hlt">filaments</span> occupy the center of sarcomeres where they partially overlap with thin <span class="hlt">filaments</span>. The sliding of thick <span class="hlt">filaments</span> past thin <span class="hlt">filaments</span> is a highly regulated process that occurs in an ATP-dependent manner driving muscle contraction. In addition to myosin that makes up the backbone of the thick <span class="hlt">filament</span>, four other proteins which are intimately bound to the thick <span class="hlt">filament</span>, myosin binding protein-C, titin, myomesin, and obscurin play important structural and regulatory roles. Consistent with this, mutations in the respective genes have been associated with idiopathic and congenital forms of skeletal and cardiac myopathies. In this review, we aim to summarize our <span class="hlt">current</span> knowledge on the molecular structure, subcellular localization, interacting partners, function, modulation via posttranslational modifications, and disease involvement of these five major proteins that comprise the thick <span class="hlt">filament</span> of striated muscle cells. © 2018 American Physiological Society. Compr Physiol 8:631-709, 2018. Copyright © 2018 American Physiological Society. All rights reserved.</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://adsabs.harvard.edu/abs/2001PhyC..354..265T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001PhyC..354..265T"><span>The effective resistance between twisted superconducting <span class="hlt">filaments</span> in tapes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Takács, S.; Iwakuma, M.; Funaki, K.</p> <p>2001-05-01</p> <p>We consider two mechanisms, which influence the effective resistance between crossing strands on flat cables or <span class="hlt">filaments</span> in twisted tapes. The one-layer classical Rutherford-type cable and the tapes with twisted BSCCO <span class="hlt">filaments</span> in silver matrix are taken as analogous cases. The amount of the matrix between strands or <span class="hlt">filaments</span> increases the effective conductance compared with the direct <span class="hlt">current</span> paths (determined by the touching area of the <span class="hlt">filaments</span>). The increase factor is about two and can easily be suppressed by other effects, like the contact resistance between the superconductor and the matrix. The second mechanism is due to the existence of induced voltage between any points of crossing <span class="hlt">filaments</span>. This leads to an additional effective conductance, proportional to the square of the total number of <span class="hlt">filaments</span>. Both effects are not very important for isotropic superconductors, but due to the strong anisotropy of critical parameters they can dominate for high temperature superconductors. The first one may partially compensate the influence of the usually weaker critical <span class="hlt">current</span> density perpendicular to the tape. The contribution due to the second effect can explain the higher resistivity of the matrix in BSCCO tapes compared with pure silver. It seems that to obtain low AC coupling losses in BSCCO tapes, structures with small <span class="hlt">filament</span> number are required.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1999PhDT.......226G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1999PhDT.......226G"><span>Production, characterization, and modeling of mineral filled polypropylene <span class="hlt">filaments</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>George, Brian Robert</p> <p>1999-11-01</p> <p>This research produced mineral filled polypropylene <span class="hlt">filaments</span> using a variety of fillers, characterized these <span class="hlt">filaments</span>, and attempted to model their mechanical properties with <span class="hlt">current</span> composite models. Also, these <span class="hlt">filaments</span> were compared with bone to determine if they are suitable for modeling the mechanical properties of bone. Fillers used consist of wollastonite, talc, calcium carbonate, titanium dioxide, and hydroxyapatite. Fillers and polypropylene chips were combined and extruded into rods with the use of a mixer. The rods were chipped up and then formed into <span class="hlt">filaments</span> through melt extrusion utilizing a piston extruder. <span class="hlt">Filaments</span> with volume fractions of filler of 0.05, 0.10, 0.15, and 0.20 were produced. Additionally, some methods of trying to improve the properties of these <span class="hlt">filaments</span> were attempted, but did not result in any significant property improvements. The fillers and <span class="hlt">filaments</span> were visually characterized with a scanning electron microscope. Cross-sections, <span class="hlt">filament</span> outer surfaces, fracture surfaces, and longitudinal cut open surfaces were viewed in this manner. Those <span class="hlt">filaments</span> with anisotropic filler had some oriented filler particles, while all <span class="hlt">filaments</span> suffered from poor adhesion between the polypropylene and the filler as well as agglomerations of filler particles. Twenty specimens of each <span class="hlt">filament</span> were tensile tested and the average tenacity, strain, and modulus were calculated. <span class="hlt">Filaments</span> containing talc, talc and wollastonite, titanium dioxide, or hydroxyapatite suffered from a drastic transition from ductile to brittle with the addition of 0.05 volume fraction of filler. This is evidenced by the sharp decrease in strain at this volume fraction of filler when compared to the strain of the unfilled polypropylene <span class="hlt">filament</span>. Additionally, these same <span class="hlt">filaments</span> suffered a sharp decrease in tenacity at the same volume fraction. These instant decreases are attributed to the agglomerations of filler in the <span class="hlt">filament</span>. Generally, the modulus of the</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/1996SuScT...9.1099T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1996SuScT...9.1099T"><span>Solution spinning of a high-? oxide superconductor: the effect of poly(vinyl alcohol) spinning medium on the critical <span class="hlt">current</span> density of melt-processed ? superconducting <span class="hlt">filaments</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tomita, Hisayo; Sunohara, Makoto; Goto, Tomoko; Takahashi, Kiyohisa</p> <p>1996-12-01</p> <p>The precursor 0953-2048/9/12/014/img9 <span class="hlt">filament</span> was prepared by solution spinning through a homogeneous aqueous poly(vinyl alcohol) (PVA) solution of Y, Ba and Cu acetates. The solution spinning was successfully performed using PVA with degrees of polymerization (DP) of 1700 and 2450 and a degree of saponification of 85 mol%. The as-drawn <span class="hlt">filament</span> was heated to remove volatile components and partially melted to generate a superconducting phase. The effects of the DP of PVA and a content of mixed acetates in the precursor <span class="hlt">filament</span> on the critical <span class="hlt">current</span> density 0953-2048/9/12/014/img10 of the melt-processed <span class="hlt">filament</span> were examined. The higher 0953-2048/9/12/014/img11 was obtained for the <span class="hlt">filament</span> spun from PVA solution of higher DP and lower acetate content. The highest 0953-2048/9/12/014/img11 value of 0953-2048/9/12/014/img13 at 77 K and 0 T was achieved for the <span class="hlt">filament</span> spun from the DP 2450 PVA with an acetate to PVA ratio of two.</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://adsabs.harvard.edu/abs/2000JGR...10527531F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2000JGR...10527531F"><span>Pulsating midmorning auroral arcs, <span class="hlt">filamentation</span> of a mixing region in a flank boundary layer, and ULF waves observed during a Polar-Svalbard conjunction</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Farrugia, C. J.; Sandholt, P. E.; Maynard, N. C.; Burke, W. J.; Scudder, J. D.; Ober, D. M.; Moen, J.; Russell, C. T.</p> <p>2000-12-01</p> <p>Magnetically conjugate observations by the HYDRA and the Magnetic Field Experiment instruments on Polar, meridian-scanning photometers and all-sky imagers at Ny-Ålesund, and International Monitor for Auroral Geomagnetic Effects (IMAGE) magnetometers on November 30, 1997, illustrate aspects of magnetosphere-ionosphere coupling at 0900-1000 magnetic local times (MLT) and 70°-80° magnetic latitudes and their dependence on interplanetary parameters. Initially, Polar crossed a boundary layer on closed field lines where magnetospheric and magnetosheath plasmas are mixed. This region contains <span class="hlt">filaments</span> where magnetospheric electron and ion fluxes are enhanced. These <span class="hlt">filaments</span> are associated with field-aligned <span class="hlt">current</span> structures embedded within the large-scale region 1 (R1) <span class="hlt">current</span>. Ground auroral imagery document the presence at this time of discrete, east-west aligned arcs, which are in one-to-one correspondence with the <span class="hlt">filaments</span>. Temporal variations present in these auroral arcs correlate with Pc 5 pulsations and are probably related to modulations in the interplanetary electric field. The auroral observations indicate that the <span class="hlt">filamented</span> mixing region persisted for many tens of minutes, suggesting a spatial structuring. The data suggest further that the <span class="hlt">filamented</span>, mixing region is an important source of the R1 <span class="hlt">current</span> and the associated midmorning arcs. When the interplanetary magnetic field (IMF) turned strongly north, Polar had entered the dayside extension of the central plasma <span class="hlt">sheet</span>/region 2 <span class="hlt">current</span> system where it and the underlying ground magnetometers recorded a clear field line resonance of frequency ~2.4 mHz (Pc 5 range). The source of these oscillations is most likely the Kelvin-Helmholtz instability. Subsequent to the IMF northward turning, the multiple arcs were replaced by a single auroral form to the north of Ny-Ålesund (at 1000 MLT) in the vicinity of the westward edge of the cusp. ULF pulsation activity changed to the Pc 3-4 range in the regime of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22493821-investigation-effect-resistivity-scrape-off-layer-filaments-using-three-dimensional-simulations','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22493821-investigation-effect-resistivity-scrape-off-layer-filaments-using-three-dimensional-simulations"><span>Investigation of the effect of resistivity on scrape off layer <span class="hlt">filaments</span> using three-dimensional simulations</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>Easy, L., E-mail: le590@york.ac.uk; CCFE, Culham Science Centre, Abingdon OX14 3DB; Militello, F.</p> <p>2016-01-15</p> <p>The propagation of <span class="hlt">filaments</span> in the Scrape Off Layer (SOL) of tokamaks largely determines the plasma profiles in the region. In a conduction limited SOL, parallel temperature gradients are expected, such that the resistance to parallel <span class="hlt">currents</span> is greater at the target than further upstream. Since the perpendicular motion of an isolated <span class="hlt">filament</span> is largely determined by balance of <span class="hlt">currents</span> that flow through it, this may be expected to affect <span class="hlt">filament</span> transport. 3D simulations have thus been used to study the influence of enhanced parallel resistivity on the dynamics of <span class="hlt">filaments</span>. <span class="hlt">Filaments</span> with the smallest perpendicular length scales, which weremore » inertially limited at low resistivity (meaning that polarization rather than parallel <span class="hlt">currents</span> determines their radial velocities), were unaffected by resistivity. For larger <span class="hlt">filaments</span>, faster velocities were produced at higher resistivities due to two mechanisms. First parallel <span class="hlt">currents</span> were reduced and polarization <span class="hlt">currents</span> were enhanced, meaning that the inertial regime extended to larger <span class="hlt">filaments</span>, and second, a potential difference formed along the parallel direction so that higher potentials were produced in the region of the <span class="hlt">filament</span> for the same amount of <span class="hlt">current</span> to flow into the sheath. These results indicate that broader SOL profiles could be produced at higher resistivities.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014PhBio..11a1001A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014PhBio..11a1001A"><span>Methods for modeling cytoskeletal and DNA <span class="hlt">filaments</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Andrews, Steven S.</p> <p>2014-02-01</p> <p>This review summarizes the models that researchers use to represent the conformations and dynamics of cytoskeletal and DNA <span class="hlt">filaments</span>. It focuses on models that address individual <span class="hlt">filaments</span> in continuous space. Conformation models include the freely jointed, Gaussian, angle-biased chain (ABC), and wormlike chain (WLC) models, of which the first three bend at discrete joints and the last bends continuously. Predictions from the WLC model generally agree well with experiment. Dynamics models include the Rouse, Zimm, stiff rod, dynamic WLC, and reptation models, of which the first four apply to isolated <span class="hlt">filaments</span> and the last to entangled <span class="hlt">filaments</span>. Experiments show that the dynamic WLC and reptation models are most accurate. They also show that biological <span class="hlt">filaments</span> typically experience strong hydrodynamic coupling and/or constrained motion. Computer simulation methods that address <span class="hlt">filament</span> dynamics typically compute <span class="hlt">filament</span> segment velocities from local forces using the Langevin equation and then integrate these velocities with explicit or implicit methods; the former are more versatile and the latter are more efficient. Much remains to be discovered in biological <span class="hlt">filament</span> modeling. In particular, <span class="hlt">filament</span> dynamics in living cells are not well understood, and <span class="hlt">current</span> computational methods are too slow and not sufficiently versatile. Although primarily a review, this paper also presents new statistical calculations for the ABC and WLC models. Additionally, it corrects several discrepancies in the literature about bending and torsional persistence length definitions, and their relations to flexural and torsional rigidities.</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://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3249369','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3249369"><span>The Regulation of <span class="hlt">Filamentous</span> Growth in Yeast</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Cullen, Paul J.; Sprague, George F.</p> <p>2012-01-01</p> <p><span class="hlt">Filamentous</span> growth is a nutrient-regulated growth response that occurs in many fungal species. In pathogens, <span class="hlt">filamentous</span> growth is critical for host–cell attachment, invasion into tissues, and virulence. The budding yeast Saccharomyces cerevisiae undergoes <span class="hlt">filamentous</span> growth, which provides a genetically tractable system to study the molecular basis of the response. <span class="hlt">Filamentous</span> growth is regulated by evolutionarily conserved signaling pathways. One of these pathways is a mitogen activated protein kinase (MAPK) pathway. A remarkable feature of the <span class="hlt">filamentous</span> growth MAPK pathway is that it is composed of factors that also function in other pathways. An intriguing challenge therefore has been to understand how pathways that share components establish and maintain their identity. Other canonical signaling pathways—rat sarcoma/protein kinase A (RAS/PKA), sucrose nonfermentable (SNF), and target of rapamycin (TOR)—also regulate <span class="hlt">filamentous</span> growth, which raises the question of how signals from multiple pathways become integrated into a coordinated response. Together, these pathways regulate cell differentiation to the <span class="hlt">filamentous</span> type, which is characterized by changes in cell adhesion, cell polarity, and cell shape. How these changes are accomplished is also discussed. High-throughput genomics approaches have recently uncovered new connections to <span class="hlt">filamentous</span> growth regulation. These connections suggest that <span class="hlt">filamentous</span> growth is a more complex and globally regulated behavior than is <span class="hlt">currently</span> appreciated, which may help to pave the way for future investigations into this eukaryotic cell differentiation behavior. PMID:22219507</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/2017APS..MAR.A4007S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017APS..MAR.A4007S"><span>Broken Detailed Balance of <span class="hlt">Filament</span> Dynamics in Active Networks</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schmidt, Christoph F.; Gladrow, Jannes; Fakhri, Nikta; Mackintosh, Fred C.; Broedersz, Chase</p> <p></p> <p>Endogenous embedded semiflexible <span class="hlt">filaments</span> such as microtubules, or added <span class="hlt">filaments</span> such as single- walled carbon nanotubes can be used as novel tools to noninvasively track equilibrium and nonequilibrium fluctuations in biopolymer networks. We analytically calculated shape fluctuations of semi- flexible probe <span class="hlt">filaments</span> in a viscoelastic environment, driven out of equilibrium by motor activity. Transverse bending fluctuations of the probe <span class="hlt">filaments</span> can be decomposed into dynamic normal modes. We find that these modes no longer evolve independently under non-equilibrium driving. This effective mode coupling results in nonzero circulatory <span class="hlt">currents</span> in a conformational phase space, reflecting a violation of detailed balance. We present predictions for the characteristic frequencies associated with these <span class="hlt">currents</span> and investigate how the temporal signatures of motor activity determine mode correlations, which we find to be consistent with recent experiments on microtubules embedded in cytoskeletal networks.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24423375','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24423375"><span>Optical spectroscopy using gas-phase femtosecond laser <span class="hlt">filamentation</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Odhner, Johanan; Levis, Robert</p> <p>2014-01-01</p> <p>Femtosecond laser <span class="hlt">filamentation</span> occurs as a dynamic balance between the self-focusing and plasma defocusing of a laser pulse to produce ultrashort radiation as brief as a few optical cycles. This unique source has many properties that make it attractive as a nonlinear optical tool for spectroscopy, such as propagation at high intensities over extended distances, self-shortening, white-light generation, and the formation of an underdense plasma. The plasma channel that constitutes a single <span class="hlt">filament</span> and whose position in space can be controlled by its input parameters can span meters-long distances, whereas multifilamentation of a laser beam can be sustained up to hundreds of meters in the atmosphere. In this review, we briefly summarize the <span class="hlt">current</span> understanding and use of laser <span class="hlt">filaments</span> for spectroscopic investigations of molecules. A theoretical framework of <span class="hlt">filamentation</span> is presented, along with recent experimental evidence supporting the established understanding of <span class="hlt">filamentation</span>. Investigations carried out on vibrational and rotational spectroscopy, <span class="hlt">filament</span>-induced breakdown, fluorescence spectroscopy, and backward lasing are discussed.</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/2016PhRvL.116x8301G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PhRvL.116x8301G"><span>Broken Detailed Balance of <span class="hlt">Filament</span> Dynamics in Active Networks</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gladrow, J.; Fakhri, N.; MacKintosh, F. C.; Schmidt, C. F.; Broedersz, C. P.</p> <p>2016-06-01</p> <p>Myosin motor proteins drive vigorous steady-state fluctuations in the actin cytoskeleton of cells. Endogenous embedded semiflexible <span class="hlt">filaments</span> such as microtubules, or added <span class="hlt">filaments</span> such as single-walled carbon nanotubes are used as novel tools to noninvasively track equilibrium and nonequilibrium fluctuations in such biopolymer networks. Here, we analytically calculate shape fluctuations of semiflexible probe <span class="hlt">filaments</span> in a viscoelastic environment, driven out of equilibrium by motor activity. Transverse bending fluctuations of the probe <span class="hlt">filaments</span> can be decomposed into dynamic normal modes. We find that these modes no longer evolve independently under nonequilibrium driving. This effective mode coupling results in nonzero circulatory <span class="hlt">currents</span> in a conformational phase space, reflecting a violation of detailed balance. We present predictions for the characteristic frequencies associated with these <span class="hlt">currents</span> and investigate how the temporal signatures of motor activity determine mode correlations, which we find to be consistent with recent experiments on microtubules embedded in cytoskeletal networks.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018JAP...123h3901H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018JAP...123h3901H"><span>Pulse measurement of the hot spot <span class="hlt">current</span> in a NbTiN superconducting <span class="hlt">filament</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Harrabi, K.; Mekki, A.; Kunwar, S.; Maneval, J. P.</p> <p>2018-02-01</p> <p>We have studied the voltage response of superconducting NbTiN <span class="hlt">filaments</span> to a step-pulse of over-critical <span class="hlt">current</span> I > Ic. The <span class="hlt">current</span> induces the destruction of the Cooper pairs and initiates different mechanisms of dissipation depending on the bath temperature T. For the sample investigated, and for T above a certain T*, not far from Tc, the resistance manifests itself in the form of a phase-slip center, which turns into a normal hot spot (HS) as the step-pulse is given larger amplitudes. However, at all temperatures below T*, the destruction of superconductivity still occurs at Ic(T), but leads directly to an ever-growing HS. By lowering the <span class="hlt">current</span> amplitude during the pulse, one can produce a steady HS and thus define a threshold HS <span class="hlt">current</span> Ih(T). That is achieved by combining two levels of <span class="hlt">current</span>, the first and larger one to initiate an HS, the second one to search for constant voltage response. The double diagram of the functions Ic(T) and Ih(T) was plotted in the T-range Tc/2 < T < Tc, and their crossing found at T* = (8.07 ± 0.07) K.</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('https://www.ncbi.nlm.nih.gov/pubmed/27074222','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27074222"><span>Mutation-specific effects on thin <span class="hlt">filament</span> length in thin <span class="hlt">filament</span> myopathy.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Winter, Josine M de; Joureau, Barbara; Lee, Eun-Jeong; Kiss, Balázs; Yuen, Michaela; Gupta, Vandana A; Pappas, Christopher T; Gregorio, Carol C; Stienen, Ger J M; Edvardson, Simon; Wallgren-Pettersson, Carina; Lehtokari, Vilma-Lotta; Pelin, Katarina; Malfatti, Edoardo; Romero, Norma B; Engelen, Baziel G van; Voermans, Nicol C; Donkervoort, Sandra; Bönnemann, C G; Clarke, Nigel F; Beggs, Alan H; Granzier, Henk; Ottenheijm, Coen A C</p> <p>2016-06-01</p> <p>Thin <span class="hlt">filament</span> myopathies are among the most common nondystrophic congenital muscular disorders, and are caused by mutations in genes encoding proteins that are associated with the skeletal muscle thin <span class="hlt">filament</span>. Mechanisms underlying muscle weakness are poorly understood, but might involve the length of the thin <span class="hlt">filament</span>, an important determinant of force generation. We investigated the sarcomere length-dependence of force, a functional assay that provides insights into the contractile strength of muscle fibers as well as the length of the thin <span class="hlt">filaments</span>, in muscle fibers from 51 patients with thin <span class="hlt">filament</span> myopathy caused by mutations in NEB, ACTA1, TPM2, TPM3, TNNT1, KBTBD13, KLHL40, and KLHL41. Lower force generation was observed in muscle fibers from patients of all genotypes. In a subset of patients who harbor mutations in NEB and ACTA1, the lower force was associated with downward shifted force-sarcomere length relations, indicative of shorter thin <span class="hlt">filaments</span>. Confocal microscopy confirmed shorter thin <span class="hlt">filaments</span> in muscle fibers of these patients. A conditional Neb knockout mouse model, which recapitulates thin <span class="hlt">filament</span> myopathy, revealed a compensatory mechanism; the lower force generation that was associated with shorter thin <span class="hlt">filaments</span> was compensated for by increasing the number of sarcomeres in series. This allowed muscle fibers to operate at a shorter sarcomere length and maintain optimal thin-thick <span class="hlt">filament</span> overlap. These findings might provide a novel direction for the development of therapeutic strategies for thin <span class="hlt">filament</span> myopathy patients with shortened thin <span class="hlt">filament</span> lengths. Ann Neurol 2016;79:959-969. © 2016 American Neurological Association.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4911820','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4911820"><span>Mutation-Specific Effects on Thin <span class="hlt">Filament</span> Length in Thin <span class="hlt">Filament</span> Myopathy</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>de Winter, Josine M.; Joureau, Barbara; Lee, Eun-Jeong; Kiss, Balázs; Yuen, Michaela; Gupta, Vandana A.; Pappas, Christopher T.; Gregorio, Carol C.; Stienen, Ger J. M.; Edvardson, Simon; Wallgren-Pettersson, Carina; Lehtokari, Vilma-Lotta; Pelin, Katarina; Malfatti, Edoardo; Romero, Norma B.; van Engelen, Baziel G.; Voermans, Nicol C.; Donkervoort, Sandra; Bönnemann, C. G.; Clarke, Nigel F.; Beggs, Alan H.; Granzier, Henk; Ottenheijm, Coen A. C.</p> <p>2016-01-01</p> <p>Objective Thin <span class="hlt">filament</span> myopathies are among the most common nondystrophic congenital muscular disorders, and are caused by mutations in genes encoding proteins that are associated with the skeletal muscle thin <span class="hlt">filament</span>. Mechanisms underlying muscle weakness are poorly understood, but might involve the length of the thin <span class="hlt">filament</span>, an important determinant of force generation. Methods We investigated the sarcomere length-dependence of force, a functional assay that provides insights into the contractile strength of muscle fibers as well as the length of the thin <span class="hlt">filaments</span>, in muscle fibers from 51 patients with thin <span class="hlt">filament</span> myopathy caused by mutations in NEB, ACTA1, TPM2, TPM3, TNNT1, KBTBD13, KLHL40, and KLHL41. Results Lower force generation was observed in muscle fibers from patients of all genotypes. In a subset of patients who harbor mutations in NEB and ACTA1, the lower force was associated with downward shifted force–sarcomere length relations, indicative of shorter thin <span class="hlt">filaments</span>. Confocal microscopy confirmed shorter thin <span class="hlt">filaments</span> in muscle fibers of these patients. A conditional Neb knockout mouse model, which recapitulates thin <span class="hlt">filament</span> myopathy, revealed a compensatory mechanism; the lower force generation that was associated with shorter thin <span class="hlt">filaments</span> was compensated for by increasing the number of sarcomeres in series. This allowed muscle fibers to operate at a shorter sarcomere length and maintain optimal thin–thick <span class="hlt">filament</span> overlap. Interpretation These findings might provide a novel direction for the development of therapeutic strategies for thin <span class="hlt">filament</span> myopathy patients with shortened thin <span class="hlt">filament</span> lengths. PMID:27074222</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22162951-diagnosis-femtosecond-plasma-filament-channeling-microwaves-along-filament','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22162951-diagnosis-femtosecond-plasma-filament-channeling-microwaves-along-filament"><span>Diagnosis of femtosecond plasma <span class="hlt">filament</span> by channeling microwaves along the <span class="hlt">filament</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>Alshershby, Mostafa; Ren, Yu; Qin, Jiang</p> <p>2013-05-20</p> <p>We introduce a simple, fast, and non-intrusive experimental method to obtain the basic parameters of femtosecond laser-generated plasma <span class="hlt">filament</span>. The method is based on the channeling of microwaves along both a plasma <span class="hlt">filament</span> and a well-defined conducting wire. By comparing the detected microwaves that propagate along the plasma <span class="hlt">filament</span> and a copper wire with known conductivity and spatial dimension, the basic parameters of the plasma <span class="hlt">filament</span> can be easily obtained. As a result of the possibility of channeling microwave radiation along the plasma <span class="hlt">filament</span>, we were then able to obtain the plasma density distribution along the <span class="hlt">filament</span> length.</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('http://adsabs.harvard.edu/abs/2018JPlPh..84c9002S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018JPlPh..84c9002S"><span>Conditions for the onset of the <span class="hlt">current</span> <span class="hlt">filamentation</span> instability in the laboratory</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Shukla, N.; Vieira, J.; Muggli, P.; Sarri, G.; Fonseca, R.</p> <p>2018-06-01</p> <p>The <span class="hlt">current</span> <span class="hlt">filamentation</span> instability (CFI) is capable of generating strong magnetic fields relevant to the explanation of radiation processes in astrophysical objects and leads to the onset of particle acceleration in collisionless shocks. Probing such extreme scenarios in the laboratory is still an open challenge. In this work, we investigate the possibility of using neutral -~e+$ beams to explore the CFI with realistic parameters, by performing two-dimensional particle-in-cell simulations. We show that CFI can occur unless the rate at which the beam expands due to finite beam emittance is larger than the CFI growth rate and as long as the role of the competing electrostatic two-stream instability (TSI) is negligible. We also show that the longitudinal energy spread, typical of plasma-based accelerated electron-positron fireball beams, plays a minor role in the growth of CFI in these scenarios.</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('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-tailed 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('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> </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('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('https://www.ncbi.nlm.nih.gov/pubmed/17872439','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17872439"><span>Lighting the universe with <span class="hlt">filaments</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Gao, Liang; Theuns, Tom</p> <p>2007-09-14</p> <p>The first stars in the universe form when chemically pristine gas heats as it falls into dark-matter potential wells, cools radiatively because of the formation of molecular hydrogen, and becomes self-gravitating. Using supercomputer simulations, we demonstrated that the stars' properties depend critically on the <span class="hlt">currently</span> unknown nature of the dark matter. If the dark-matter particles have intrinsic velocities that wipe out small-scale structure, then the first stars form in <span class="hlt">filaments</span> with lengths on the order of the free-streaming scale, which can be approximately 10(20) meters (approximately 3 kiloparsecs, corresponding to a baryonic mass of approximately 10(7) solar masses) for realistic "warm dark matter" candidates. Fragmentation of the <span class="hlt">filaments</span> forms stars with a range of masses, which may explain the observed peculiar element abundance pattern of extremely metal-poor stars, whereas coalescence of fragments and stars during the <span class="hlt">filament</span>'s ultimate collapse may seed the supermassive black holes that lurk in the centers of most massive galaxies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018GeoRL..45.2566S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018GeoRL..45.2566S"><span>Does a Local B-Minimum Appear in the Tail <span class="hlt">Current</span> <span class="hlt">Sheet</span> During a Substorm Growth Phase?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sergeev, V. A.; Gordeev, E. I.; Merkin, V. G.; Sitnov, M. I.</p> <p>2018-03-01</p> <p>Magnetic configurations with dBz/dr > 0 in the midtail <span class="hlt">current</span> <span class="hlt">sheet</span> 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 <span class="hlt">current</span> <span class="hlt">sheet</span>. 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 <span class="hlt">sheet</span> at distances 15-20 RE. We discuss infrequent observations of such events taking into account recent results of global magnetohydrodynamic simulations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://eric.ed.gov/?q=standard+AND+model+AND+physics&pg=7&id=EJ896423','ERIC'); return false;" href="https://eric.ed.gov/?q=standard+AND+model+AND+physics&pg=7&id=EJ896423"><span>Calibration and Temperature Profile of a Tungsten <span class="hlt">Filament</span> Lamp</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>de Izarra, Charles; Gitton, Jean-Michel</p> <p>2010-01-01</p> <p>The goal of this work proposed for undergraduate students and teachers is the calibration of a tungsten <span class="hlt">filament</span> lamp from electric measurements that are both simple and precise, allowing to determine the temperature of tungsten <span class="hlt">filament</span> as a function of the <span class="hlt">current</span> intensity. This calibration procedure was first applied to a conventional filament…</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('http://adsabs.harvard.edu/abs/2015SMaS...24l5021C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015SMaS...24l5021C"><span>Fused <span class="hlt">filament</span> 3D printing of ionic polymer-metal composites (IPMCs)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Carrico, James D.; Traeden, Nicklaus W.; Aureli, Matteo; Leang, Kam K.</p> <p>2015-12-01</p> <p>This paper describes a new three-dimensional (3D) fused <span class="hlt">filament</span> additive manufacturing (AM) technique in which electroactive polymer <span class="hlt">filament</span> material is used to build soft active 3D structures, layer by layer. Specifically, the unique actuation and sensing properties of ionic polymer-metal composites (IPMCs) are exploited in 3D printing to create electroactive polymer structures for application in soft robotics and bio-inspired systems. The process begins with extruding a precursor material (non-acid Nafion precursor resin) into a thermoplastic <span class="hlt">filament</span> for 3D printing. The <span class="hlt">filament</span> is then used by a custom-designed 3D printer to manufacture the desired soft polymer structures, layer by layer. Since at this stage the 3D-printed samples are not yet electroactive, a chemical functionalization process follows, consisting in hydrolyzing the precursor samples in an aqueous solution of potassium hydroxide and dimethyl sulfoxide. Upon functionalization, metal electrodes are applied on the samples through an electroless plating process, which enables the 3D-printed IPMC structures to be controlled by voltage signals for actuation (or to act as sensors). This innovative AM process is described in detail and the performance of 3D printed IPMC actuators is compared to an IPMC actuator fabricated from commercially available Nafion <span class="hlt">sheet</span> material. The experimental results show comparable performance between the two types of actuators, demonstrating the potential and feasibility of creating functional 3D-printed IPMCs.</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('https://www.osti.gov/biblio/22218522-filament-velocity-scaling-laws-warm-ions','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22218522-filament-velocity-scaling-laws-warm-ions"><span><span class="hlt">Filament</span> velocity scaling laws for warm 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>Manz, P.; Max-Planck-Institut für Plasmaphysik, EURATOM Assoziation, Boltzmannstr. 2, 85748 Garching; Carralero, D.</p> <p>2013-10-15</p> <p>The dynamics of <span class="hlt">filaments</span> or blobs in the scrape-off layer of magnetic fusion devices are studied by magnitude estimates of a comprehensive drift-interchange-Alfvén fluid model. The standard blob models are reproduced in the cold ion case. Even though usually neglected, in the scrape-off layer, the ion temperature can exceed the electron temperature by an order of magnitude. The ion pressure affects the dynamics of <span class="hlt">filaments</span> amongst others by adding up to the interchange drive and the polarisation <span class="hlt">current</span>. It is shown how both effects modify the scaling laws for <span class="hlt">filament</span> velocity in dependence of its size. Simplifications for experimentally relevantmore » limit regimes are given. These are the sheath dissipation, collisional, and electromagnetic regime.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1996IJMSI.156...31D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1996IJMSI.156...31D"><span>Electron emission controller with pulsed heating of <span class="hlt">filament</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Durakiewicz, Tomasz</p> <p>1996-11-01</p> <p>A novel circuit has been invented for the versatile and safe stabilization of the electron emission <span class="hlt">current</span> (Ie) produced by a hot <span class="hlt">filament</span> in mass spectrometers or in ionization gauges. The voltage signal, which is directly proportional to Ie, is provided to the inverting input of a comparator, whereas the noninverting input is connected to the reference voltage. In addition to the commonly used negative feedback loop, a positive feedback loop was introduced by siting a resistor between the noninverting input and the output of the comparator, which results in a pulsation of the <span class="hlt">filament</span> voltage. The pulses are rectangular, so that the power dissipated by the transistor in the <span class="hlt">filament</span> power supply circuit is radically reduced. To refine the switching action of the transistor, the output of the comparator is connected through a capacitor to the transistor gate. A concise discussion of the phase shift between Ie, the <span class="hlt">filament</span> temperature Tf, and the <span class="hlt">filament</span> voltage Vf, including time constants for different modes of power dissipation, is included.</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> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015APS..DFDE25001S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015APS..DFDE25001S"><span>Nonlinear Binormal Flow of Vortex <span class="hlt">Filaments</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Strong, Scott; Carr, Lincoln</p> <p>2015-11-01</p> <p>With the <span class="hlt">current</span> advances in vortex imaging of Bose-Einstein condensates occurring at the Universities of Arizona, São Paulo and Cambridge, interest in vortex <span class="hlt">filament</span> dynamics is experiencing a resurgence. Recent simulations, Salman (2013), depict dissipative mechanisms resulting from vortex ring emissions and Kelvin wave generation associated with vortex self-intersections. As the local induction approximation fails to capture reconnection events, it lacks a similar dissipative mechanism. On the other hand, Strong&Carr (2012) showed that the exact representation of the velocity field induced by a curved segment of vortex contains higher-order corrections expressed in powers of curvature. This nonlinear binormal flow can be transformed, Hasimoto (1972), into a fully nonlinear equation of Schrödinger type. Continued transformation, Madelung (1926), reveals that the <span class="hlt">filament</span>'s square curvature obeys a quasilinear scalar conservation law with source term. This implies a broader range of <span class="hlt">filament</span> dynamics than is possible with the integrable linear binormal flow. In this talk we show the affect higher-order corrections have on <span class="hlt">filament</span> dynamics and discuss physical scales for which they may be witnessed in future experiments. Partially supported by NSF.</p> </li> <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('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/2014ApJ...794..149C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014ApJ...794..149C"><span>Direct Evidence of an Eruptive, <span class="hlt">Filament</span>-hosting Magnetic Flux Rope Leading to a Fast Solar Coronal Mass Ejection</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chen, Bin; Bastian, T. S.; Gary, D. E.</p> <p>2014-10-01</p> <p>Magnetic flux ropes (MFRs) are believed to be at the heart of solar coronal mass ejections (CMEs). A well-known example is the prominence cavity in the low corona that sometimes makes up a three-part white-light (WL) CME upon its eruption. Such a system, which is usually observed in quiet-Sun regions, has long been suggested to be the manifestation of an MFR with relatively cool <span class="hlt">filament</span> material collecting near its bottom. However, observational evidence of eruptive, <span class="hlt">filament</span>-hosting MFR systems has been elusive for those originating in active regions. By utilizing multi-passband extreme-ultraviolet (EUV) observations from Solar Dynamics Observatory/Atmospheric Imaging Assembly, we present direct evidence of an eruptive MFR in the low corona that exhibits a hot envelope and a cooler core; the latter is likely the upper part of a <span class="hlt">filament</span> that undergoes a partial eruption, which is later observed in the upper corona as the coiled kernel of a fast, WL CME. This MFR-like structure exists more than 1 hr prior to its eruption, and displays successive stages of dynamical evolution, in which both ideal and non-ideal physical processes may be involved. The timing of the MFR kinematics is found to be well correlated with the energy release of the associated long-duration C1.9 flare. We suggest that the long-duration flare is the result of prolonged energy release associated with the vertical <span class="hlt">current</span> <span class="hlt">sheet</span> induced by the erupting MFR.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19740019288','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19740019288"><span>A penny-shaped crack in a <span class="hlt">filament</span> reinforced matrix. 1: The <span class="hlt">filament</span> model</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Erdogan, F.; Pacella, A. H.</p> <p>1973-01-01</p> <p>The electrostatic problem of a penny-shaped crack in an elastic matrix which reinforced by <span class="hlt">filaments</span> or fibers perpendicular to the plane of the crack was studied. The elastic <span class="hlt">filament</span> model was developed for application to evaluation studies of the stress intensity factor along the periphery of the crack, the stresses in the <span class="hlt">filaments</span> or fibers, and the interface shear between the matrix and the <span class="hlt">filaments</span> or fibers. The requirements expected of the model are a sufficiently accurate representation of the <span class="hlt">filament</span> and applicability to the interaction problems involving a cracked elastic continuum with multi-<span class="hlt">filament</span> reinforcements. The technique for developing the model and numerical examples of it are shown.</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('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3196151','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3196151"><span>Tropomodulin Capping of Actin <span class="hlt">Filaments</span> in Striated Muscle Development and Physiology</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Gokhin, David S.; Fowler, Velia M.</p> <p>2011-01-01</p> <p>Efficient striated muscle contraction requires precise assembly and regulation of diverse actin <span class="hlt">filament</span> systems, most notably the sarcomeric thin <span class="hlt">filaments</span> of the contractile apparatus. By capping the pointed ends of actin <span class="hlt">filaments</span>, tropomodulins (Tmods) regulate actin <span class="hlt">filament</span> assembly, lengths, and stability. Here, we explore the <span class="hlt">current</span> understanding of the expression patterns, localizations, and functions of Tmods in both cardiac and skeletal muscle. We first describe the mechanisms by which Tmods regulate myofibril assembly and thin <span class="hlt">filament</span> lengths, as well as the roles of closely related Tmod family variants, the leiomodins (Lmods), in these processes. We also discuss emerging functions for Tmods in the sarcoplasmic reticulum. This paper provides abundant evidence that Tmods are key structural regulators of striated muscle cytoarchitecture and physiology. PMID:22013379</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('https://www.osti.gov/biblio/22663672-formation-eruption-process-filament-active-region-noaa','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22663672-formation-eruption-process-filament-active-region-noaa"><span>Formation and Eruption Process of a <span class="hlt">Filament</span> in Active Region NOAA 12241</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, Jincheng; Yan, Xiaoli; Qu, ZhongQuan</p> <p></p> <p>In order to better understand active-region <span class="hlt">filaments</span>, we present an intensive study on the formation and eruption of a <span class="hlt">filament</span> in active region NOAA 12241 during the period from 2014 December 18 to 19. Using observations from the Helioseismic and Magnetic Imager (HMI) vector magnetograms, we investigate the helicity injection rate, Lorentz force, and vertical electric <span class="hlt">current</span> in the entire region associated with the <span class="hlt">filament</span>. The helicity injection rate before eruption is found to be larger than that after eruption, while the vertical electric <span class="hlt">current</span> undergoes an increase at first and then a gradual decrease, similar to what the magneticmore » flux undergoes. Meanwhile, we find that the right part of the <span class="hlt">filament</span> is formed by magnetic reconnection between two bundles of magnetic field lines while the left part originated from shearing motion. The interaction of the two parts causes the eruption of this <span class="hlt">filament</span>. The mean horizontal magnetic fields in the vicinity of the magnetic polarity inversion line (PIL) enhance rapidly during the eruption. Another striking phenomenon, where the vertical electric <span class="hlt">currents</span> close to the magnetic PIL suddenly expand toward two sides during the eruption, is found. We propose that this fascinating feature is associated with the release of energy during the eruption.« less</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('http://adsabs.harvard.edu/abs/1987Natur.326..805H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1987Natur.326..805H"><span>Sliding movement of single actin <span class="hlt">filaments</span> on one-headed myosin <span class="hlt">filaments</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Harada, Yoshie; Noguchi, Akira; Kishino, Akiyoshi; Yanagida, Toshio</p> <p>1987-04-01</p> <p>The myosin molecule consists of two heads, each of which contains an enzymatic active site and an actin-binding site. The fundamental problem of whether the two heads function independently or cooperatively during muscle contraction has been studied by methods using an actomyosin thread1, superprecipitation2-4 and chemical modification of muscle fibres5. No clear conclusion has yet been reached. We have approached this question using an assay system in which sliding movements of fluorescently labelled single actin <span class="hlt">filaments</span> along myosin <span class="hlt">filaments</span> can be observed directly6,7. Here, we report direct measurement of the sliding of single actin <span class="hlt">filaments</span> along one-headed myosin <span class="hlt">filaments</span> in which the density of heads was varied over a wide range. Our results show that cooperative interaction between the two heads of myosin is not essential for inducing the sliding movement of actin <span class="hlt">filaments</span>.</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 tail <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 tail 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('https://www.osti.gov/servlets/purl/1454792','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/1454792"><span>Transition of Femtosecond-<span class="hlt">Filament</span>-Solid Interactions from Single to Multiple <span class="hlt">Filament</span> Regime</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>Skrodzki, P. J.; Burger, M.; Jovanovic, I.</p> <p></p> <p>High-peak-power fs-laser <span class="hlt">filaments</span> offer unique characteristics attractive to remote sensing via techniques such as remote laser-induced breakdown spectroscopy (R-LIBS). The dynamics of several ablation mechanisms following the interaction between a <span class="hlt">filament</span> and a solid determines the emission strength and reproducibility of target plasma, which is of relevance for R-LIBS applications. Here, we investigate the space- and time-resolved dynamics of ionic and atomic emission from copper as well as the surrounding atmosphere in order to understand limitations of fs-<span class="hlt">filament</span>-ablation for standoff energy delivery. Furthermore, we probe the shock front produced from <span class="hlt">filament</span>-target interaction using time-resolved shadowgraphy and infer laser-material coupling efficienciesmore » for both single and multiple <span class="hlt">filament</span> regimes through analysis of shock expansion with the Sedov model for point detonation. The results provide insight into plasma structure for the range of peak powers up to 30 times the critical power for <span class="hlt">filamentation</span> P cr. Despite the stochastic nucleation of multiple <span class="hlt">filaments</span> at peak-powers greater than 16 P cr, emission of ionic and neutral species increases with pump beam intensity, and short-lived nitrogen emission originating from the ambient is consistently observed. Ultimately, results suggest favorable scaling of emission intensity from target species on the laser pump energy, furthering the prospects for use of <span class="hlt">filament</span>-solid interactions for remote sensing.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1454792-transition-femtosecond-filament-solid-interactions-from-single-multiple-filament-regime','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1454792-transition-femtosecond-filament-solid-interactions-from-single-multiple-filament-regime"><span>Transition of Femtosecond-<span class="hlt">Filament</span>-Solid Interactions from Single to Multiple <span class="hlt">Filament</span> Regime</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Skrodzki, P. J.; Burger, M.; Jovanovic, I.</p> <p>2017-10-06</p> <p>High-peak-power fs-laser <span class="hlt">filaments</span> offer unique characteristics attractive to remote sensing via techniques such as remote laser-induced breakdown spectroscopy (R-LIBS). The dynamics of several ablation mechanisms following the interaction between a <span class="hlt">filament</span> and a solid determines the emission strength and reproducibility of target plasma, which is of relevance for R-LIBS applications. Here, we investigate the space- and time-resolved dynamics of ionic and atomic emission from copper as well as the surrounding atmosphere in order to understand limitations of fs-<span class="hlt">filament</span>-ablation for standoff energy delivery. Furthermore, we probe the shock front produced from <span class="hlt">filament</span>-target interaction using time-resolved shadowgraphy and infer laser-material coupling efficienciesmore » for both single and multiple <span class="hlt">filament</span> regimes through analysis of shock expansion with the Sedov model for point detonation. The results provide insight into plasma structure for the range of peak powers up to 30 times the critical power for <span class="hlt">filamentation</span> P cr. Despite the stochastic nucleation of multiple <span class="hlt">filaments</span> at peak-powers greater than 16 P cr, emission of ionic and neutral species increases with pump beam intensity, and short-lived nitrogen emission originating from the ambient is consistently observed. Ultimately, results suggest favorable scaling of emission intensity from target species on the laser pump energy, furthering the prospects for use of <span class="hlt">filament</span>-solid interactions for remote sensing.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016Nanos...813976K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016Nanos...813976K"><span>Kinetic factors determining conducting <span class="hlt">filament</span> formation in solid polymer electrolyte based planar devices</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Krishnan, Karthik; Aono, Masakazu; Tsuruoka, Tohru</p> <p>2016-07-01</p> <p>Resistive switching characteristics and conducting <span class="hlt">filament</span> formation dynamics in solid polymer electrolyte (SPE) based planar-type atomic switches, with opposing active Ag and inert Pt electrodes, have been investigated by optimizing the device configuration and experimental parameters such as the gap distance between the electrodes, the salt inclusion in the polymer matrix, and the compliance <span class="hlt">current</span> applied in <span class="hlt">current</span>-voltage measurements. The high ionic conductivities of SPE enabled us to make scanning electron microscopy observations of the <span class="hlt">filament</span> formation processes in the sub-micrometer to micrometer ranges. It was found that switching behaviour and <span class="hlt">filament</span> growth morphology depend strongly on several kinetic factors, such as the redox reaction rate at the electrode-polymer interfaces, ion mobility in the polymer matrix, electric field strength, and the reduction sites for precipitation. Different <span class="hlt">filament</span> formations, resulting from unidirectional and dendritic growth behaviours, can be controlled by tuning specified parameters, which in turn improves the stability and performance of SPE-based devices.Resistive switching characteristics and conducting <span class="hlt">filament</span> formation dynamics in solid polymer electrolyte (SPE) based planar-type atomic switches, with opposing active Ag and inert Pt electrodes, have been investigated by optimizing the device configuration and experimental parameters such as the gap distance between the electrodes, the salt inclusion in the polymer matrix, and the compliance <span class="hlt">current</span> applied in <span class="hlt">current</span>-voltage measurements. The high ionic conductivities of SPE enabled us to make scanning electron microscopy observations of the <span class="hlt">filament</span> formation processes in the sub-micrometer to micrometer ranges. It was found that switching behaviour and <span class="hlt">filament</span> growth morphology depend strongly on several kinetic factors, such as the redox reaction rate at the electrode-polymer interfaces, ion mobility in the polymer matrix, electric field strength</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('http://adsabs.harvard.edu/abs/2017A%26A...601A..94R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017A%26A...601A..94R"><span>Galactic cold cores. VIII. <span class="hlt">Filament</span> formation and evolution: <span class="hlt">Filament</span> properties in context with evolutionary models</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rivera-Ingraham, A.; Ristorcelli, I.; Juvela, M.; Montillaud, J.; Men'shchikov, A.; Malinen, J.; Pelkonen, V.-M.; Marston, A.; Martin, P. G.; Pagani, L.; Paladini, R.; Paradis, D.; Ysard, N.; Ward-Thompson, D.; Bernard, J.-P.; Marshall, D. J.; Montier, L.; Tóth, L. V.</p> <p>2017-05-01</p> <p>Context. The onset of star formation is intimately linked with the presence of massive unstable filamentary structures. These <span class="hlt">filaments</span> are therefore key for theoretical models that aim to reproduce the observed characteristics of the star formation process in the Galaxy. Aims: As part of the <span class="hlt">filament</span> study carried out by the Herschel Galactic Cold Cores Key Programme, here we study and discuss the <span class="hlt">filament</span> properties presented in GCC VII (Paper I) in context with theoretical models of <span class="hlt">filament</span> formation and evolution. Methods: A conservatively selected sample of <span class="hlt">filaments</span> located at a distance D< 500 pc was extracted from the GCC fields with the getfilaments algorithm. The physical structure of the <span class="hlt">filaments</span> was quantified according to two main components: the central (Gaussian) region of the <span class="hlt">filament</span> (core component), and the power-law-like region dominating the <span class="hlt">filament</span> column density profile at larger radii (wing component). The properties and behaviour of these components relative to the total linear mass density of the <span class="hlt">filament</span> and the column density of its environment were compared with the predictions from theoretical models describing the evolution of <span class="hlt">filaments</span> under gravity-dominated conditions. Results: The feasibility of a transition from a subcritical to supercritical state by accretion at any given time is dependent on the combined effect of <span class="hlt">filament</span> intrinsic properties and environmental conditions. Reasonably self-gravitating (high Mline,core) <span class="hlt">filaments</span> in dense environments (AV≳ 3 mag) can become supercritical on timescales of t 1 Myr by accreting mass at constant or decreasing width. The trend of increasing Mline,tot (Mline,core and Mline,wing) and ridge AV with background for the <span class="hlt">filament</span> population also indicates that the precursors of star-forming <span class="hlt">filaments</span> evolve coevally with their environment. The simultaneous increase of environment and <span class="hlt">filament</span> AV explains the observed association between dense environments and high Mline,core values</p> </li> <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 tail 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('http://adsabs.harvard.edu/abs/2006SuScT..19..323B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006SuScT..19..323B"><span>Relationship between architecture, <span class="hlt">filament</span> breakage and critical <span class="hlt">current</span> decay in Nb3Sn composite wires repeatedly in-plane bent at room temperature</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Badica, P.; Awaji, S.; Oguro, H.; Nishijima, G.; Watanabe, K.</p> <p>2006-04-01</p> <p>Six Nb3Sn composite wires with different architectures ('central and near-the-edge reinforcement') were repeatedly in-plane bent at room temperature (in-plane 'pre-bending'). Breakage behaviour was revealed from scanning electron microscopy observations by semi-quantitative analysis of the <span class="hlt">filament</span> crack formation and evolution. Cracks are formed in the transversal and longitudinal directions. Transversal cracks show some tolerance to the applied bending strain due to the fact that <span class="hlt">filaments</span> are composite materials; residual Nb core can arrest development of a partial transversal crack initiated in the Nb3Sn outer part of the <span class="hlt">filament</span>. Together with the density of cracks C and the evolution of this parameter with pre-bending strain, ɛpb, in different regions of the wire, R-ɛpb curves are important to understand breakage behaviour of the wires. R is the ratio (number of full transversal cracks)/(number of full transversal cracks + number of partial transversal cracks). Parameters C and R allow us to reveal and satisfactorily understand the wire architecture—breakage—critical <span class="hlt">current</span> decay relationship when pre-bending treatment is applied. As a consequence, breakage criteria necessary to minimize Ic decay were defined and the positive influence of the reinforcement in preventing breakage was observed. It was also found that, in this regard, more Nb in the CuNb reinforcement, for the investigated wires, is better, if the heat treatment for the wire synthesis is performed at 670 °C for 96 h. A different heat treatment, 650 °C for 240 h, is less efficient in preventing <span class="hlt">filament</span> breakage. Our results suggest the possibility of control and improvement of the breakage susceptibility of the <span class="hlt">filaments</span> in the wires and, hence, of the bending Ic decay, through the wise design of the wire architecture (i.e. by correlating design with the choice of composing materials and heat treatments).</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('https://www.osti.gov/biblio/22648601-collective-epithelial-cell-sheet-adhesion-migration-polyelectrolyte-multilayers-uniform-gradients-compliance','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22648601-collective-epithelial-cell-sheet-adhesion-migration-polyelectrolyte-multilayers-uniform-gradients-compliance"><span>Collective epithelial cell <span class="hlt">sheet</span> adhesion and migration on polyelectrolyte multilayers with uniform and gradients of compliance</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>Martinez, Jessica S.; Schlenoff, Joseph B.; Keller, Thomas C.S., E-mail: tkeller@bio.fsu.edu</p> <p></p> <p>Polyelectrolyte multilayers (PEMUs) are tunable thin films that could serve as coatings for biomedical implants. PEMUs built layer by layer with the polyanion poly(acrylic acid) (PAA) modified with a photosensitive 4-(2-hydroxyethoxy) benzophenone (PAABp) group and the polycation poly(allylamine hydrochloride) (PAH) are mechanically tunable by UV irradiation, which forms covalent bonds between the layers and increases PEMU stiffness. PAH-terminated PEMUs (PAH-PEMUs) that were uncrosslinked, UV-crosslinked to a uniform stiffness, or UV-crosslinked with an edge mask or through a neutral density optical gradient filter to form continuous compliance gradients were used to investigate how differences in PEMU stiffness affect the adhesion andmore » migration of epithelial cell <span class="hlt">sheets</span> from scales of the fish Poecilia sphenops (Black Molly) and Carassius auratus (Comet Goldfish). During the progressive collective cell migration, the edge cells (also known as ‘leader’ cells) in the <span class="hlt">sheets</span> on softer uncrosslinked PEMUs and less crosslinked regions of the gradient formed more actin <span class="hlt">filaments</span> and vinculin-containing adherens junctions and focal adhesions than formed in the <span class="hlt">sheet</span> cells on stiffer PEMUs or glass. During <span class="hlt">sheet</span> migration, the ratio of edge cell to internal cell (also known as ‘follower’ cells) motilities were greater on the softer PEMUs than on the stiffer PEMUs or glass, causing tension to develop across the <span class="hlt">sheet</span> and periods of retraction, during which the edge cells lost adhesion to the substrate and regions of the <span class="hlt">sheet</span> retracted toward the more adherent internal cell region. These retraction events were inhibited by the myosin II inhibitor Blebbistatin, which reduced the motility velocity ratios to those for <span class="hlt">sheets</span> on the stiffer PEMUs. Blebbistatin also caused disassembly of actin <span class="hlt">filaments</span>, reorganization of focal adhesions, increased cell spreading at the leading edge, as well as loss of edge cell-cell connections in epithelial cell <span class="hlt">sheets</span> on all</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.ncbi.nlm.nih.gov/pubmed/15342343','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/15342343"><span>Barrier role of actin <span class="hlt">filaments</span> in regulated mucin secretion from airway goblet cells.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ehre, Camille; Rossi, Andrea H; Abdullah, Lubna H; De Pestel, Kathleen; Hill, Sandra; Olsen, John C; Davis, C William</p> <p>2005-01-01</p> <p>Airway goblet cells secrete mucin onto mucosal surfaces under the regulation of an apical, phospholipase C/G(q)-coupled P2Y(2) receptor. We tested whether cortical actin <span class="hlt">filaments</span> negatively regulate exocytosis in goblet cells by forming a barrier between secretory granules and plasma membrane docking sites as postulated for other secretory cells. Immunostaining of human lung tissues and SPOC1 cells (an epithelial, mucin-secreting cell line) revealed an apical distribution of beta- and gamma-actin in ciliated and goblet cells. In goblet cells, actin appeared as a prominent subplasmalemmal <span class="hlt">sheet</span> lying between granules and the apical membrane, and it disappeared from SPOC1 cells activated by purinergic agonist. Disruption of actin <span class="hlt">filaments</span> with latrunculin A stimulated SPOC1 cell mucin secretion under basal and agonist-activated conditions, whereas stabilization with jasplakinolide or overexpression of beta- or gamma-actin conjugated to yellow fluorescent protein (YFP) inhibited secretion. Myristoylated alanine-rich C kinase substrate, a PKC-activated actin-plasma membrane tethering protein, was phosphorylated after agonist stimulation, suggesting a translocation to the cytosol. Scinderin (or adseverin), a Ca(2+)-activated actin <span class="hlt">filament</span> severing and capping protein was cloned from human airway and SPOC1 cells, and synthetic peptides corresponding to its actin-binding domains inhibited mucin secretion. We conclude that actin <span class="hlt">filaments</span> negatively regulate mucin secretion basally in airway goblet cells and are dynamically remodeled in agonist-stimulated cells to promote exocytosis.</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> </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/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> <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('http://adsabs.harvard.edu/abs/2017MNRAS.470.3742P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017MNRAS.470.3742P"><span>A hot X-ray <span class="hlt">filament</span> associated with A3017 galaxy cluster</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Parekh, V.; Durret, F.; Padmanabh, P.; Pandge, M. B.</p> <p>2017-09-01</p> <p>Recent simulations and observations have shown large-scale <span class="hlt">filaments</span> in the cosmic web connecting nodes, with accreting materials (baryonic and dark matter) flowing through them. <span class="hlt">Current</span> high-sensitivity observations also show that the propagation of shocks through <span class="hlt">filaments</span> can heat them up and make <span class="hlt">filaments</span> visible between two or more galaxy clusters or around massive clusters, based on optical and/or X-ray observations. We are reporting here the special case of the cluster A3017 associated with a hot <span class="hlt">filament</span>. The temperature of the <span class="hlt">filament</span> is 3.4^{-0.77}_{+1.30} keV and its length is ∼1 Mpc. We have analysed its archival Chandra data and report various properties. We also analysed GMRT 235/610 MHz radio data. Radio observations have revealed symmetric two-sided lobes that fill cavities in the A3017 cluster core region, associated with central active galactic nucleus. In the radio map, we also noticed a peculiar linear vertical radio structure in the X-ray <span class="hlt">filament</span> region which might be associated with a cosmic <span class="hlt">filament</span> shock. This radio structure could be a radio phoenix or old plasma where an old relativistic population is re-accelerated by shock propagation. Finally, we put an upper limit on the radio luminosity of the <span class="hlt">filament</span> region.</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('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-tail <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/2011Natur.474..184C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011Natur.474..184C"><span>A <span class="hlt">current</span> <span class="hlt">filamentation</span> mechanism for breaking magnetic field lines during reconnection</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Che, H.; Drake, J. F.; Swisdak, M.</p> <p>2011-06-01</p> <p>During magnetic reconnection, the field lines must break and reconnect to release the energy that drives solar and stellar flares and other explosive events in space and in the laboratory. Exactly how this happens has been unclear, because dissipation is needed to break magnetic field lines and classical collisions are typically weak. Ion-electron drag arising from turbulence, dubbed `anomalous resistivity', and thermal momentum transport are two mechanisms that have been widely invoked. Measurements of enhanced turbulence near reconnection sites in space and in the laboratory support the anomalous resistivity idea but there has been no demonstration from measurements that this turbulence produces the necessary enhanced drag. Here we report computer simulations that show that neither of the two previously favoured mechanisms controls how magnetic field lines reconnect in the plasmas of greatest interest, those in which the magnetic field dominates the energy budget. Rather, we find that when the <span class="hlt">current</span> layers that form during magnetic reconnection become too intense, they disintegrate and spread into a complex web of <span class="hlt">filaments</span> that causes the rate of reconnection to increase abruptly. This filamentary web can be explored in the laboratory or in space with satellites that can measure the resulting electromagnetic turbulence.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013PhDT.........4Q','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013PhDT.........4Q"><span>Structural and Mechanical Properties of Intermediate <span class="hlt">Filaments</span> under Extreme Conditions and Disease</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Qin, Zhao</p> <p></p> <p>Intermediate <span class="hlt">filaments</span> are one of the three major components of the cytoskeleton in eukaryotic cells. It was discovered during the recent decades that intermediate <span class="hlt">filament</span> proteins play key roles to reinforce cells subjected to large-deformation as well as participate in signal transduction. However, it is still poorly understood how the nanoscopic structure, as well as the biochemical properties of these protein molecules contribute to their biomechanical functions. In this research we investigate the material function of intermediate <span class="hlt">filaments</span> under various extreme mechanical conditions as well as disease states. We use a full atomistic model and study its response to mechanical stresses. Learning from the mechanical response obtained from atomistic simulations, we build mesoscopic models following the finer-trains-coarser principles. By using this multiple-scale model, we present a detailed analysis of the mechanical properties and associated deformation mechanisms of intermediate <span class="hlt">filament</span> network. We reveal the mechanism of a transition from alpha-helices to beta-<span class="hlt">sheets</span> with subsequent intermolecular sliding under mechanical force, which has been inferred previously from experimental results. This nanoscale mechanism results in a characteristic nonlinear force-extension curve, which leads to a delocalization of mechanical energy and prevents catastrophic fracture. This explains how intermediate <span class="hlt">filament</span> can withstand extreme mechanical deformation of > 1 00% strain despite the presence of structural defects. We combine computational and experimental techniques to investigate the molecular mechanism of Hutchinson-Gilford progeria syndrome, a premature aging disease. We find that the mutated lamin tail .domain is more compact and stable than the normal one. This altered structure and stability may enhance the association of intermediate <span class="hlt">filaments</span> with the nuclear membrane, providing a molecular mechanism of the disease. We study the nuclear membrane association</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('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2108024','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2108024"><span>CYTOPLASMIC <span class="hlt">FILAMENTS</span> OF AMOEBA PROTEUS</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Pollard, Thomas D.; Ito, Susumu</p> <p>1970-01-01</p> <p>The role of <span class="hlt">filaments</span> in consistency changes and movement in a motile cytoplasmic extract of Amoeba proteus was investigated by correlating light and electron microscopic observations with viscosity measurements. The extract is prepared by the method of Thompson and Wolpert (1963). At 0°C, this extract is nonmotile and similar in structure to ameba cytoplasm, consisting of groundplasm, vesicles, mitochondria, and a few 160 A <span class="hlt">filaments</span>. The extract undergoes striking ATP-stimulated streaming when warmed to 22°C. Two phases of movement are distinguished. During the first phase, the apparent viscosity usually increases and numerous 50–70 A <span class="hlt">filaments</span> appear in samples of the extract prepared for electron microscopy, suggesting that the increase in viscosity in caused, at least in part, by the formation of these thin <span class="hlt">filaments</span>. During this initial phase of ATP-stimulated movement, these thin <span class="hlt">filaments</span> are not detectable by phase-contrast or polarization microscopy, but later, in the second phase of movement, 70 A <span class="hlt">filaments</span> aggregate to form birefringent microscopic fibrils. A preparation of pure groundplasm with no 160 A <span class="hlt">filaments</span> or membranous organelles exhibits little or no ATP-stimulated movement, but 50–70 A <span class="hlt">filaments</span> form and aggregate into birefringent fibrils. This observation and the structural relationship of the 70 A and the 160 A <span class="hlt">filaments</span> in the motile extract suggest that both types of <span class="hlt">filaments</span> may be required for movement. These two types of <span class="hlt">filaments</span>, 50–70 A and 160 A, are also present in the cytoplasm of intact amebas. Fixed cells could not be used to study the distribution of these <span class="hlt">filaments</span> during natural ameboid movement because of difficulties in preserving the normal structure of the ameba during preparation for electron microscopy. PMID:4915451</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22587104','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22587104"><span>Defects in crystalline packings of twisted <span class="hlt">filament</span> bundles. I. Continuum theory of disclinations.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Grason, Gregory M</p> <p>2012-03-01</p> <p>We develop the theory of the coupling between in-plane order and out-of-plane geometry in twisted, two-dimensionally ordered <span class="hlt">filament</span> bundles based on the nonlinear continuum elasticity theory of columnar materials. We show that twisted textures of <span class="hlt">filament</span> backbones necessarily introduce stresses into the cross-sectional packing of bundles and that these stresses are formally equivalent to the geometrically induced stresses generated in thin elastic <span class="hlt">sheets</span> that are forced to adopt spherical curvature. As in the case of crystalline order on curved membranes, geometrically induced stresses couple elastically to the presence of topological defects in the in-plane order. We derive the effective theory of multiple disclination defects in the cross section of bundle with a fixed twist and show that above a critical degree of twist, one or more fivefold disclinations is favored in the elastic energy ground state. We study the structure and energetics of multidisclination packings based on models of equilibrium and nonequilibrium cross-sectional order.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/4915451','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/4915451"><span>Cytoplasmic <span class="hlt">filaments</span> of Amoeba proteus. I. The role of <span class="hlt">filaments</span> in consistency changes and movement.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Pollard, T D; Ito, S</p> <p>1970-08-01</p> <p>The role of <span class="hlt">filaments</span> in consistency changes and movement in a motile cytoplasmic extract of Amoeba proteus was investigated by correlating light and electron microscopic observations with viscosity measurements. The extract is prepared by the method of Thompson and Wolpert (1963). At 0 degrees C, this extract is nonmotile and similar in structure to ameba cytoplasm, consisting of groundplasm, vesicles, mitochondria, and a few 160 A <span class="hlt">filaments</span>. The extract undergoes striking ATP-stimulated streaming when warmed to 22 degrees C. Two phases of movement are distinguished. During the first phase, the apparent viscosity usually increases and numerous 50-70 A <span class="hlt">filaments</span> appear in samples of the extract prepared for electron microscopy, suggesting that the increase in viscosity in caused, at least in part, by the formation of these thin <span class="hlt">filaments</span>. During this initial phase of ATP-stimulated movement, these thin <span class="hlt">filaments</span> are not detectable by phase-contrast or polarization microscopy, but later, in the second phase of movement, 70 A <span class="hlt">filaments</span> aggregate to form birefringent microscopic fibrils. A preparation of pure groundplasm with no 160 A <span class="hlt">filaments</span> or membranous organelles exhibits little or no ATP-stimulated movement, but 50-70 A <span class="hlt">filaments</span> form and aggregate into birefringent fibrils. This observation and the structural relationship of the 70 A and the 160 A <span class="hlt">filaments</span> in the motile extract suggest that both types of <span class="hlt">filaments</span> may be required for movement. These two types of <span class="hlt">filaments</span>, 50-70 A and 160 A, are also present in the cytoplasm of intact amebas. Fixed cells could not be used to study the distribution of these <span class="hlt">filaments</span> during natural ameboid movement because of difficulties in preserving the normal structure of the ameba during preparation for electron microscopy.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25730393','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25730393"><span>Solid friction between soft <span class="hlt">filaments</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ward, Andrew; Hilitski, Feodor; Schwenger, Walter; Welch, David; Lau, A W C; Vitelli, Vincenzo; Mahadevan, L; Dogic, Zvonimir</p> <p>2015-06-01</p> <p>Any macroscopic deformation of a <span class="hlt">filamentous</span> bundle is necessarily accompanied by local sliding and/or stretching of the constituent <span class="hlt">filaments</span>. Yet the nature of the sliding friction between two aligned <span class="hlt">filaments</span> interacting through multiple contacts remains largely unexplored. Here, by directly measuring the sliding forces between two bundled F-actin <span class="hlt">filaments</span>, we show that these frictional forces are unexpectedly large, scale logarithmically with sliding velocity as in solid-like friction, and exhibit complex dependence on the <span class="hlt">filaments</span>' overlap length. We also show that a reduction of the frictional force by orders of magnitude, associated with a transition from solid-like friction to Stokes's drag, can be induced by coating F-actin with polymeric brushes. Furthermore, we observe similar transitions in <span class="hlt">filamentous</span> microtubules and bacterial flagella. Our findings demonstrate how altering a <span class="hlt">filament</span>'s elasticity, structure and interactions can be used to engineer interfilament friction and thus tune the properties of fibrous composite materials.</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://ntrs.nasa.gov/search.jsp?R=19850021587&hterms=Electric+current&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DElectric%2Bcurrent','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19850021587&hterms=Electric+current&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DElectric%2Bcurrent"><span>Inferred flows of electric <span class="hlt">currents</span> in solar active regions</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Ding, Y. J.; Hong, Q. F.; Hagyard, M. J.; Deloach, A. C.</p> <p>1985-01-01</p> <p>Techniques to identify sources of major <span class="hlt">current</span> systems in active regions and their channels of flow are explored. Measured photospheric vector magnetic fields together with high resolution white light and H-alpha photographs provide the data base to derive the <span class="hlt">current</span> systems in the photosphere and chromosphere of a solar active region. Simple mathematical constructions of active region fields and <span class="hlt">currents</span> are used to interpret these data under the assumptions that the fields in the lower atmosphere (below 200 km) may not be force free but those in the chromosphere and higher are. The results obtained for the complex active region AR 2372 are: (1) Spots exhibiting significant spiral structure in the penumbral <span class="hlt">filaments</span> were the source of vertical <span class="hlt">currents</span> at the photospheric surface; (2) Magnetic neutral lines where the transverse magnetic field was strongly sheared were channels along which a strong <span class="hlt">current</span> system flowed; (3) The inferred <span class="hlt">current</span> systems produced a neutral <span class="hlt">sheet</span> and oppositely-flowing <span class="hlt">currents</span> in the area of the magnetic delta configuration that was the site of flaring.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013A%26A...559A.112M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013A%26A...559A.112M"><span>Weak-lensing detection of intracluster <span class="hlt">filaments</span> with ground-based data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Maturi, Matteo; Merten, Julian</p> <p>2013-11-01</p> <p>According to the <span class="hlt">current</span> standard model of cosmology, matter in the Universe arranges itself along a network of filamentary structure. These <span class="hlt">filaments</span> connect the main nodes of this so-called "cosmic web", which are clusters of galaxies. Although its large-scale distribution is clearly characterized by numerical simulations, constraining the dark-matter content of the cosmic web in reality turns out to be difficult. The natural method of choice is gravitational lensing. However, the direct detection and mapping of the elusive <span class="hlt">filament</span> signal is challenging and in this work we present two methods that are specifically tailored to achieve this task. A linear matched filter aims at detecting the smooth mass-component of <span class="hlt">filaments</span> and is optimized to perform a shear decomposition that follows the anisotropic component of the lensing signal. <span class="hlt">Filaments</span> clearly inherit this property due to their morphology. At the same time, the contamination arising from the central massive cluster is controlled in a natural way. The <span class="hlt">filament</span> 1σ detection is of about κ ~ 0.01 - 0.005 according to the filter's template width and length, enabling the detection of structures beyond reach with other approaches. The second, complementary method seeks to detect the clumpy component of <span class="hlt">filaments</span>. The detection is determined by the number density of subclump identifications in an area enclosing the potential <span class="hlt">filament</span>, as was found within the observed field with the filter approach. We tested both methods against mocked observations based on realistic N-body simulations of filamentary structure and proved the feasibility of detecting <span class="hlt">filaments</span> with ground-based data.</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> </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/28984591','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28984591"><span>Curcumin Inhibits Tau Aggregation and Disintegrates Preformed Tau <span class="hlt">Filaments</span> in vitro.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Rane, Jitendra Subhash; Bhaumik, Prasenjit; Panda, Dulal</p> <p>2017-01-01</p> <p>The pathological aggregation of tau is a common feature of most of the neuronal disorders including frontotemporal dementia, Parkinson's disease, and Alzheimer's disease. The inhibition of tau aggregation is considered to be one of the important strategies for treating these neurodegenerative diseases. Curcumin, a natural polyphenolic molecule, has been reported to have neuroprotective ability. In this work, curcumin was found to bind to adult tau and fetal tau with a dissociation constant of 3.3±0.4 and 8±1 μM, respectively. Molecular docking studies indicated a putative binding site of curcumin in the microtubule-binding region of tau. Using several complementary techniques, including dynamic light scattering, thioflavin S fluorescence, 90° light scattering, electron microscopy, and atomic force microscopy, curcumin was found to inhibit the aggregation of tau. The dynamic light scattering analysis and atomic force microscopic images revealed that curcumin inhibits the oligomerization of tau. Curcumin also disintegrated preformed tau oligomers. Using Far-UV circular dichroism, curcumin was found to inhibit the β-<span class="hlt">sheets</span> formation in tau indicating that curcumin inhibits an initial step of tau aggregation. In addition, curcumin inhibited tau fibril formation. Furthermore, the effect of curcumin on the preformed tau <span class="hlt">filaments</span> was analyzed by atomic force microscopy, transmission electron microscopy, and 90° light scattering. Curcumin treatment disintegrated preformed tau <span class="hlt">filaments</span>. The results indicated that curcumin inhibited the oligomerization of tau and could disaggregate tau <span class="hlt">filaments</span>.</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('https://www.osti.gov/biblio/22140202-hubble-space-telescope-observations-dusty-filaments-hercules-evidence-entrainment','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22140202-hubble-space-telescope-observations-dusty-filaments-hercules-evidence-entrainment"><span>HUBBLE SPACE TELESCOPE OBSERVATIONS OF DUSTY <span class="hlt">FILAMENTS</span> IN HERCULES A: EVIDENCE FOR ENTRAINMENT</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>O'Dea, C. P.; Kharb, P.; Baum, S. A.</p> <p>2013-07-01</p> <p>We present U-, V-, and I-band images of the host galaxy of Hercules A (3C 348) obtained with HST/WFC3/UVIS. We find a network of dusty <span class="hlt">filaments</span> which are more complex and extended than seen in earlier Hubble Space Telescope (HST) observations. The <span class="hlt">filaments</span> are associated with a faint blue continuum light (possibly from young stars) and faint H{alpha} emission. It seems likely that the cold gas and dust has been stripped from a companion galaxy now seen as a secondary nucleus. There are dusty <span class="hlt">filaments</span> aligned with the base of the jets on both eastern and western sides of themore » galaxy. The morphology of the <span class="hlt">filaments</span> is different on the two sides-the western <span class="hlt">filaments</span> are fairly straight, while the eastern <span class="hlt">filaments</span> are mainly in two loop-like structures. We suggest that despite the difference in morphologies, both sets of <span class="hlt">filaments</span> have been entrained in a slow-moving boundary layer outside the relativistic flow. As suggested by Fabian et al., magnetic fields in the <span class="hlt">filaments</span> may stabilize them against disruption. We consider a speculative scenario to explain the relation between the radio source and the shock and cavities in the hot intracluster medium seen in the Chandra data. We suggest that the radio source originally ({approx}60 Myr ago) propagated along a position angle of {approx}35 Degree-Sign where it created the shock and cavities. The radio source axis changed to its <span class="hlt">current</span> orientation ({approx}100 Degree-Sign ) possibly due to a supermassive black hole merger and began its <span class="hlt">current</span> epoch of activity about 20 Myr ago.« less</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('https://www.ncbi.nlm.nih.gov/pubmed/24908038','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24908038"><span>Role of <span class="hlt">filament</span> annealing in the kinetics and thermodynamics of nucleated polymerization.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Michaels, Thomas C T; Knowles, Tuomas P J</p> <p>2014-06-07</p> <p>The formation of nanoscale protein <span class="hlt">filaments</span> from soluble precursor molecules through nucleated polymerization is a common form of supra-molecular assembly phenomenon. This process underlies the generation of a range of both functional and pathological structures in nature. <span class="hlt">Filament</span> breakage has emerged as a key process controlling the kinetics of the growth reaction since it increases the number of <span class="hlt">filament</span> ends in the system that can act as growth sites. In order to ensure microscopic reversibility, however, the inverse process of fragmentation, end-to-end annealing of <span class="hlt">filaments</span>, is a necessary component of a consistent description of such systems. Here, we combine Smoluchowski kinetics with nucleated polymerization models to generate a master equation description of protein fibrillization, where <span class="hlt">filamentous</span> structures can undergo end-to-end association, in addition to elongation, fragmentation, and nucleation processes. We obtain self-consistent closed-form expressions for the growth kinetics and discuss the key physics that emerges from considering <span class="hlt">filament</span> fusion relative to <span class="hlt">current</span> fragmentation only models. Furthermore, we study the key time scales that describe relaxation to equilibrium.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012APS..MARB40002W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012APS..MARB40002W"><span>Actin <span class="hlt">filament</span> curvature biases branching direction</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, Evan; Risca, Viviana; Chaudhuri, Ovijit; Chia, Jia-Jun; Geissler, Phillip; Fletcher, Daniel</p> <p>2012-02-01</p> <p>Actin <span class="hlt">filaments</span> are key components of the cellular machinery, vital for a wide range of processes ranging from cell motility to endocytosis. Actin <span class="hlt">filaments</span> can branch, and essential in this process is a protein complex known as the Arp2/3 complex, which nucleate new ``daughter'' <span class="hlt">filaments</span> from pre-existing ``mother'' <span class="hlt">filaments</span> by attaching itself to the mother <span class="hlt">filament</span>. Though much progress has been made in understanding the Arp2/3-actin junction, some very interesting questions remain. In particular, F-actin is a dynamic polymer that undergoes a wide range of fluctuations. Prior studies of the Arp2/3-actin junction provides a very static notion of Arp2/3 binding. The question we ask is how differently does the Arp2/3 complex interact with a straight <span class="hlt">filament</span> compared to a bent <span class="hlt">filament</span>? In this study, we used Monte Carlo simulations of a surface-tethered worm-like chain to explore possible mechanisms underlying the experimental observation that there exists preferential branch formation by the Arp2/3 complex on the convex face of a curved <span class="hlt">filament</span>. We show that a fluctuation gating model in which Arp2/3 binding to the actin <span class="hlt">filament</span> is dependent upon a rare high-local-curvature shape fluctuation of the <span class="hlt">filament</span> is consistent with the experimental data.</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 tail 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://www.osti.gov/biblio/22654248-sympathetic-solar-filament-eruptions','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22654248-sympathetic-solar-filament-eruptions"><span>SYMPATHETIC SOLAR <span class="hlt">FILAMENT</span> 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>Wang, Rui; Liu, Ying D.; Zimovets, Ivan</p> <p>2016-08-10</p> <p>The 2015 March 15 coronal mass ejection as one of the two that together drove the largest geomagnetic storm of solar cycle 24 so far was associated with sympathetic <span class="hlt">filament</span> eruptions. We investigate the relations between the different <span class="hlt">filaments</span> involved in the eruption. A surge-like small-scale <span class="hlt">filament</span> motion is confirmed as the trigger that initiated the erupting <span class="hlt">filament</span> with multi-wavelength observations and using a forced magnetic field extrapolation method. When the erupting <span class="hlt">filament</span> moved to an open magnetic field region, it experienced an obvious acceleration process and was accompanied by a C-class flare and the rise of another larger filamentmore » that eventually failed to erupt. We measure the decay index of the background magnetic field, which presents a critical height of 118 Mm. Combining with a potential field source surface extrapolation method, we analyze the distributions of the large-scale magnetic field, which indicates that the open magnetic field region may provide a favorable condition for F2 rapid acceleration and have some relation with the largest solar storm. The comparison between the successful and failed <span class="hlt">filament</span> eruptions suggests that the confining magnetic field plays an important role in the preconditions for an eruption.« less</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> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19740050329&hterms=fiber+reinforced+concrete&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dfiber%2Breinforced%2Bconcrete','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19740050329&hterms=fiber+reinforced+concrete&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dfiber%2Breinforced%2Bconcrete"><span>A penny-shaped crack in a <span class="hlt">filament</span>-reinforced matrix. I - The <span class="hlt">filament</span> model. II - The crack problem</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Erdogan, F.; Pacella, A. H.</p> <p>1974-01-01</p> <p>The study deals with the elastostatic problem of a penny-shaped crack in an elastic matrix which is reinforced by <span class="hlt">filaments</span> or fibers perpendicular to the plane of the crack. An elastic <span class="hlt">filament</span> model is first developed, followed by consideration of the application of the model to the penny-shaped crack problem in which the <span class="hlt">filaments</span> of finite length are asymmetrically distributed around the crack. Since the primary interest is in the application of the results to studies relating to the fracture of fiber or <span class="hlt">filament</span>-reinforced composites and reinforced concrete, the main emphasis of the study is on the evaluation of the stress intensity factor along the periphery of the crack, the stresses in the <span class="hlt">filaments</span> or fibers, and the interface shear between the matrix and the <span class="hlt">filaments</span> or fibers. Using the <span class="hlt">filament</span> model developed, the elastostatic interaction problem between a penny-shaped crack and a slender inclusion or <span class="hlt">filament</span> in an elastic matrix is formulated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://eric.ed.gov/?q=light&pg=6&id=EJ1099918','ERIC'); return false;" href="https://eric.ed.gov/?q=light&pg=6&id=EJ1099918"><span>Tungsten <span class="hlt">Filament</span> Fire</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>Ruiz, Michael J.; Perkins, James</p> <p>2016-01-01</p> <p>We safely remove the outer glass bulb from an incandescent lamp and burn up the tungsten <span class="hlt">filament</span> after the glass is removed. This demonstration dramatically illustrates the necessity of a vacuum or inert gas for the environment surrounding the tungsten <span class="hlt">filament</span> inside the bulb. Our approach has added historical importance since the incandescent…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/20602989','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/20602989"><span>Morphology and rheology in <span class="hlt">filamentous</span> cultivations.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wucherpfennig, T; Kiep, K A; Driouch, H; Wittmann, C; Krull, R</p> <p>2010-01-01</p> <p>Because of their metabolic diversity, high production capacity, secretion efficiency, and capability of carrying out posttranslational modifications, <span class="hlt">filamentous</span> fungi are widely exploited as efficient cell factories in the production of metabolites, bioactive substances, and native or heterologous proteins, respectively. There is, however, a complex relationship between the morphology of these microorganisms, transport phenomena, the viscosity of the cultivation broth, and related productivity. The morphological characteristics vary between freely dispersed mycelia and distinct pellets of aggregated biomass, every growth form having a distinct influence on broth rheology. Hence, the advantages and disadvantages for mycelial or pellet cultivation have to be balanced out carefully. Because of the still inadequate understanding of the morphogenesis of <span class="hlt">filamentous</span> microorganisms, fungal morphology is often a bottleneck of productivity in industrial production. To obtain an optimized production process, it is of great importance to gain a better understanding of the molecular and cell biology of these microorganisms as well as the relevant approaches in biochemical engineering. In this chapter, morphology and growth of <span class="hlt">filamentous</span> fungi are described, with special attention given to specific problems as they arise from fungal growth forms; growth and mass transfer in fungal biopellets are discussed as an example. To emphasize the importance of the flow behavior of <span class="hlt">filamentous</span> cultivation broths, an introduction to rheology is also given, reviewing important rheological models and recent studies concerning rheological parameters. Furthermore, <span class="hlt">current</span> knowledge on morphology and productivity in relation to the environom is outlined in the last section of this review. Copyright 2010 Elsevier Inc. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2752800','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2752800"><span>Hierarchical Structure Controls Nanomechanical Properties of Vimentin Intermediate <span class="hlt">Filaments</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>Qin, Zhao; Kreplak, Laurent; Buehler, Markus J.</p> <p>2009-01-01</p> <p>Intermediate <span class="hlt">filaments</span> (IFs), in addition to microtubules and microfilaments, are one of the three major components of the cytoskeleton in eukaryotic cells, playing a vital role in mechanotransduction and in providing mechanical stability to cells. Despite the importance of IF mechanics for cell biology and cell mechanics, the structural basis for their mechanical properties remains unknown. Specifically, our understanding of fundamental <span class="hlt">filament</span> properties, such as the basis for their great extensibility, stiffening properties, and their exceptional mechanical resilience remains limited. This has prevented us from answering fundamental structure-function relationship questions related to the biomechanical role of intermediate <span class="hlt">filaments</span>, which is crucial to link structure and function in the protein material's biological context. Here we utilize an atomistic-level model of the human vimentin dimer and tetramer to study their response to mechanical tensile stress, and describe a detailed analysis of the mechanical properties and associated deformation mechanisms. We observe a transition from alpha-helices to beta-<span class="hlt">sheets</span> with subsequent interdimer sliding under mechanical deformation, which has been inferred previously from experimental results. By upscaling our results we report, for the first time, a quantitative comparison to experimental results of IF nanomechanics, showing good agreement. Through the identification of links between structures and deformation mechanisms at distinct hierarchical levels, we show that the multi-scale structure of IFs is crucial for their characteristic mechanical properties, in particular their ability to undergo severe deformation of ≈300% strain without breaking, facilitated by a cascaded activation of a distinct deformation mechanisms operating at different levels. This process enables IFs to combine disparate properties such as mechanosensitivity, strength and deformability. Our results enable a new paradigm in studying</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19806221','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19806221"><span>Hierarchical structure controls nanomechanical properties of vimentin intermediate <span class="hlt">filaments</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Qin, Zhao; Kreplak, Laurent; Buehler, Markus J</p> <p>2009-10-06</p> <p>Intermediate <span class="hlt">filaments</span> (IFs), in addition to microtubules and microfilaments, are one of the three major components of the cytoskeleton in eukaryotic cells, playing a vital role in mechanotransduction and in providing mechanical stability to cells. Despite the importance of IF mechanics for cell biology and cell mechanics, the structural basis for their mechanical properties remains unknown. Specifically, our understanding of fundamental <span class="hlt">filament</span> properties, such as the basis for their great extensibility, stiffening properties, and their exceptional mechanical resilience remains limited. This has prevented us from answering fundamental structure-function relationship questions related to the biomechanical role of intermediate <span class="hlt">filaments</span>, which is crucial to link structure and function in the protein material's biological context. Here we utilize an atomistic-level model of the human vimentin dimer and tetramer to study their response to mechanical tensile stress, and describe a detailed analysis of the mechanical properties and associated deformation mechanisms. We observe a transition from alpha-helices to beta-<span class="hlt">sheets</span> with subsequent interdimer sliding under mechanical deformation, which has been inferred previously from experimental results. By upscaling our results we report, for the first time, a quantitative comparison to experimental results of IF nanomechanics, showing good agreement. Through the identification of links between structures and deformation mechanisms at distinct hierarchical levels, we show that the multi-scale structure of IFs is crucial for their characteristic mechanical properties, in particular their ability to undergo severe deformation of approximately 300% strain without breaking, facilitated by a cascaded activation of a distinct deformation mechanisms operating at different levels. This process enables IFs to combine disparate properties such as mechanosensitivity, strength and deformability. Our results enable a new paradigm in</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22370056-unwinding-motion-twisted-active-region-filament','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22370056-unwinding-motion-twisted-active-region-filament"><span>Unwinding motion of a twisted active region <span class="hlt">filament</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>Yan, X. L.; Xue, Z. K.; Kong, D. F.</p> <p></p> <p>To better understand the structures of active region <span class="hlt">filaments</span> and the eruption process, we study an active region <span class="hlt">filament</span> eruption in active region NOAA 11082 in detail on 2010 June 22. Before the <span class="hlt">filament</span> eruption, the opposite unidirectional material flows appeared in succession along the spine of the <span class="hlt">filament</span>. The rising of the <span class="hlt">filament</span> triggered two B-class flares at the upper part of the <span class="hlt">filament</span>. As the bright material was injected into the <span class="hlt">filament</span> from the sites of the flares, the <span class="hlt">filament</span> exhibited a rapid uplift accompanying the counterclockwise rotation of the <span class="hlt">filament</span> body. From the expansion of the <span class="hlt">filament</span>,more » we can see that the <span class="hlt">filament</span> consisted of twisted magnetic field lines. The total twist of the <span class="hlt">filament</span> is at least 5π obtained by using a time slice method. According to the morphology change during the <span class="hlt">filament</span> eruption, it is found that the active region <span class="hlt">filament</span> was a twisted flux rope and its unwinding motion was like a solar tornado. We also find that there was a continuous magnetic helicity injection before and during the <span class="hlt">filament</span> eruption. It is confirmed that magnetic helicity can be transferred from the photosphere to the <span class="hlt">filament</span>. Using the extrapolated potential fields, the average decay index of the background magnetic fields over the <span class="hlt">filament</span> is 0.91. Consequently, these findings imply that the mechanism of solar <span class="hlt">filament</span> eruption could be due to the kink instability and magnetic helicity accumulation.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017MNRAS.464.4666G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017MNRAS.464.4666G"><span>Relation between halo spin and cosmic-web <span class="hlt">filaments</span> at z ≃ 3</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>González, Roberto E.; Prieto, Joaquin; Padilla, Nelson; Jimenez, Raul</p> <p>2017-02-01</p> <p>We investigate the spin evolution of dark matter haloes and their dependence on the number of connected <span class="hlt">filaments</span> from the cosmic web at high redshift (spin-<span class="hlt">filament</span> relation hereafter). To this purpose, we have simulated 5000 haloes in the mass range 5 × 109 h-1 M⊙ to 5 × 1011 h-1 M⊙ at z = 3 in cosmological N-body simulations. We confirm the relation found by Prieto et al. (2015) where haloes with fewer <span class="hlt">filaments</span> have larger spin. We also found that this relation is more significant for higher halo masses, and for haloes with a passive (no major mergers) assembly history. Another finding is that haloes with larger spin or with fewer <span class="hlt">filaments</span> have their <span class="hlt">filaments</span> more perpendicularly aligned with the spin vector. Our results point to a picture in which the initial spin of haloes is well described by tidal torque theory and then gets subsequently modified in a predictable way because of the topology of the cosmic web, which in turn is given by the <span class="hlt">currently</span> favoured Lambda cold dark matter (LCDM) model. Our spin-<span class="hlt">filament</span> relation is a prediction from LCDM that could be tested with observations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4284530','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4284530"><span>Myosin binding protein-C activates thin <span class="hlt">filaments</span> and inhibits thick <span class="hlt">filaments</span> in heart muscle cells</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Kampourakis, Thomas; Yan, Ziqian; Gautel, Mathias; Sun, Yin-Biao; Irving, Malcolm</p> <p>2014-01-01</p> <p>Myosin binding protein-C (MyBP-C) is a key regulatory protein in heart muscle, and mutations in the MYBPC3 gene are frequently associated with cardiomyopathy. However, the mechanism of action of MyBP-C remains poorly understood, and both activating and inhibitory effects of MyBP-C on contractility have been reported. To clarify the function of the regulatory N-terminal domains of MyBP-C, we determined their effects on the structure of thick (myosin-containing) and thin (actin-containing) <span class="hlt">filaments</span> in intact sarcomeres of heart muscle. We used fluorescent probes on troponin C in the thin <span class="hlt">filaments</span> and on myosin regulatory light chain in the thick <span class="hlt">filaments</span> to monitor structural changes associated with activation of demembranated trabeculae from rat ventricle by the C1mC2 region of rat MyBP-C. C1mC2 induced larger structural changes in thin <span class="hlt">filaments</span> than calcium activation, and these were still present when active force was blocked with blebbistatin, showing that C1mC2 directly activates the thin <span class="hlt">filaments</span>. In contrast, structural changes in thick <span class="hlt">filaments</span> induced by C1mC2 were smaller than those associated with calcium activation and were abolished or reversed by blebbistatin. Low concentrations of C1mC2 did not affect resting force but increased calcium sensitivity and reduced cooperativity of force and structural changes in both thin and thick <span class="hlt">filaments</span>. These results show that the N-terminal region of MyBP-C stabilizes the ON state of thin <span class="hlt">filaments</span> and the OFF state of thick <span class="hlt">filaments</span> and lead to a novel hypothesis for the physiological role of MyBP-C in the regulation of cardiac contractility. PMID:25512492</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25512492','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25512492"><span>Myosin binding protein-C activates thin <span class="hlt">filaments</span> and inhibits thick <span class="hlt">filaments</span> in heart muscle cells.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kampourakis, Thomas; Yan, Ziqian; Gautel, Mathias; Sun, Yin-Biao; Irving, Malcolm</p> <p>2014-12-30</p> <p>Myosin binding protein-C (MyBP-C) is a key regulatory protein in heart muscle, and mutations in the MYBPC3 gene are frequently associated with cardiomyopathy. However, the mechanism of action of MyBP-C remains poorly understood, and both activating and inhibitory effects of MyBP-C on contractility have been reported. To clarify the function of the regulatory N-terminal domains of MyBP-C, we determined their effects on the structure of thick (myosin-containing) and thin (actin-containing) <span class="hlt">filaments</span> in intact sarcomeres of heart muscle. We used fluorescent probes on troponin C in the thin <span class="hlt">filaments</span> and on myosin regulatory light chain in the thick <span class="hlt">filaments</span> to monitor structural changes associated with activation of demembranated trabeculae from rat ventricle by the C1mC2 region of rat MyBP-C. C1mC2 induced larger structural changes in thin <span class="hlt">filaments</span> than calcium activation, and these were still present when active force was blocked with blebbistatin, showing that C1mC2 directly activates the thin <span class="hlt">filaments</span>. In contrast, structural changes in thick <span class="hlt">filaments</span> induced by C1mC2 were smaller than those associated with calcium activation and were abolished or reversed by blebbistatin. Low concentrations of C1mC2 did not affect resting force but increased calcium sensitivity and reduced cooperativity of force and structural changes in both thin and thick <span class="hlt">filaments</span>. These results show that the N-terminal region of MyBP-C stabilizes the ON state of thin <span class="hlt">filaments</span> and the OFF state of thick <span class="hlt">filaments</span> and lead to a novel hypothesis for the physiological role of MyBP-C in the regulation of cardiac contractility.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017MsT.........15J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017MsT.........15J"><span>Fabrication of Polylactide Nanocomposite <span class="hlt">Filament</span> Using Melt Extrusion and <span class="hlt">Filament</span> Characterization for 3D Printing</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jain, Shrenik Kumar</p> <p></p> <p>Fused deposition modeling (FDM) technology uses thermoplastic <span class="hlt">filament</span> for layer by layer fabrication of objects. To make functional objects with desired properties, composite <span class="hlt">filaments</span> are required in the FDM. In this thesis, less expensive mesoporous Nano carbon (NC) and carbon nanotube (CNT) infused in Polylactide (PLA) thermoplastic <span class="hlt">filaments</span> were fabricated to improve the electrical properties and maintain sufficient strength for 3D printing. Solution blending was used for nanocomposite fabrication and melt extrusion was employed to make cylindrical <span class="hlt">filaments</span>. Mechanical and electrical properties of 1 to 20 wt% of NC and 1 to 3 wt% of CNT <span class="hlt">filaments</span> were investigated and significant improvement of conductivity (3.76 S/m) and sufficient yield strength (35MPa) were obtained. Scanning electron microscopy (SEM) images exhibited uniform dispersion of nanoparticles in polymer matrix and differential scanning calorimetry (DSC) results showed no significant changes in the glass transition temperature (Tg) for all the compositions. Perspective uses of this <span class="hlt">filament</span> are for fabrication of electrical wires in 3D printed robots, drones, prosthetics, orthotics and others.</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('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4110310','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4110310"><span>The Kinetics Underlying the Velocity of Smooth Muscle Myosin <span class="hlt">Filament</span> Sliding on Actin <span class="hlt">Filaments</span> in Vitro*</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Haldeman, Brian D.; Brizendine, Richard K.; Facemyer, Kevin C.; Baker, Josh E.; Cremo, Christine R.</p> <p>2014-01-01</p> <p>Actin-myosin interactions are well studied using soluble myosin fragments, but little is known about effects of myosin <span class="hlt">filament</span> structure on mechanochemistry. We stabilized unphosphorylated smooth muscle myosin (SMM) and phosphorylated smooth muscle myosin (pSMM) <span class="hlt">filaments</span> against ATP-induced depolymerization using a cross-linker and attached fluorescent rhodamine (XL-Rh-SMM). Electron micrographs showed that these side polar <span class="hlt">filaments</span> are very similar to unmodified <span class="hlt">filaments</span>. They are ∼0.63 μm long and contain ∼176 molecules. Rate constants for ATP-induced dissociation and ADP release from acto-myosin for <span class="hlt">filaments</span> and S1 heads were similar. Actin-activated ATPases of SMM and XL-Rh-SMM were similarly regulated. XL-Rh-pSMM <span class="hlt">filaments</span> moved processively on F-actin that was bound to a PEG brush surface. ATP dependence of <span class="hlt">filament</span> velocities was similar to that for solution ATPases at high [actin], suggesting that both processes are limited by the same kinetic step (weak to strong transition) and therefore are attachment-limited. This differs from actin sliding over myosin monomers, which is primarily detachment-limited. Fitting <span class="hlt">filament</span> data to an attachment-limited model showed that approximately half of the heads are available to move the <span class="hlt">filament</span>, consistent with a side polar structure. We suggest the low stiffness subfragment 2 (S2) domain remains unhindered during <span class="hlt">filament</span> motion in our assay. Actin-bound negatively displaced heads will impart minimal drag force because of S2 buckling. Given the ADP release rate, the velocity, and the length of S2, these heads will detach from actin before slack is taken up into a backwardly displaced high stiffness position. This mechanism explains the lack of detachment-limited kinetics at physiological [ATP]. These findings address how nonlinear elasticity in assemblies of motors leads to efficient collective force generation. PMID:24907276</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/6202700','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/6202700"><span>Epithelial cytoskeletal framework and nuclear matrix-intermediate <span class="hlt">filament</span> scaffold: three-dimensional organization and protein composition.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Fey, E G; Wan, K M; Penman, S</p> <p>1984-06-01</p> <p>Madin-Darby canine kidney (MDCK) cells grow as differentiated, epithelial colonies that display tissue-like organization. We examined the structural elements underlying the colony morphology in situ using three consecutive extractions that produce well-defined fractions for both microscopy and biochemical analysis. First, soluble proteins and phospholipid were removed with Triton X-100 in a physiological buffer. The resulting skeletal framework retained nuclei, dense cytoplasmic <span class="hlt">filament</span> networks, intercellular junctional complexes, and apical microvillar structures. Scanning electron microscopy showed that the apical cell morphology is largely unaltered by detergent extraction. Residual desmosomes, as can be seen in thin sections, were also well-preserved. The skeletal framework was visualized in three dimensions as an unembedded whole mount that revealed the <span class="hlt">filament</span> networks that were masked in Epon-embedded thin sections of the same preparation. The topography of cytoskeletal <span class="hlt">filaments</span> was relatively constant throughout the epithelial <span class="hlt">sheet</span>, particularly across intercellular borders. This ordering of epithelial skeletal <span class="hlt">filaments</span> across contiguous cell boundaries was in sharp contrast to the more independent organization of networks in autonomous cells such as fibroblasts. Further extraction removed the proteins of the salt-labile cytoskeleton and the chromatin as separate fractions, and left the nuclear matrix-intermediate <span class="hlt">filament</span> (NM-IF) scaffold. The NM-IF contained only 5% of total cellular protein, but whole mount transmission electron microscopy and immunofluorescence showed that this scaffold was organized as in the intact epithelium. Immunoblots demonstrate that vimentin, cytokeratins, desmosomal proteins, and a 52,000-mol-wt nuclear matrix protein were found almost exclusively in the NM-IF scaffold. Vimentin was largely perinuclear while the cytokeratins were localized at the cell borders. The 52,000-mol-wt nuclear matrix protein was confined to the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2113071','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2113071"><span>Epithelial cytoskeletal framework and nuclear matrix-intermediate <span class="hlt">filament</span> scaffold: three-dimensional organization and protein composition</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>1984-01-01</p> <p>Madin-Darby canine kidney (MDCK) cells grow as differentiated, epithelial colonies that display tissue-like organization. We examined the structural elements underlying the colony morphology in situ using three consecutive extractions that produce well-defined fractions for both microscopy and biochemical analysis. First, soluble proteins and phospholipid were removed with Triton X-100 in a physiological buffer. The resulting skeletal framework retained nuclei, dense cytoplasmic <span class="hlt">filament</span> networks, intercellular junctional complexes, and apical microvillar structures. Scanning electron microscopy showed that the apical cell morphology is largely unaltered by detergent extraction. Residual desmosomes, as can be seen in thin sections, were also well- preserved. The skeletal framework was visualized in three dimensions as an unembedded whole mount that revealed the <span class="hlt">filament</span> networks that were masked in Epon-embedded thin sections of the same preparation. The topography of cytoskeletal <span class="hlt">filaments</span> was relatively constant throughout the epithelial <span class="hlt">sheet</span>, particularly across intercellular borders. This ordering of epithelial skeletal <span class="hlt">filaments</span> across contiguous cell boundaries was in sharp contrast to the more independent organization of networks in autonomous cells such as fibroblasts. Further extraction removed the proteins of the salt-labile cytoskeleton and the chromatin as separate fractions, and left the nuclear matrix-intermediate <span class="hlt">filament</span> (NM-IF) scaffold. The NM-IF contained only 5% of total cellular protein, but whole mount transmission electron microscopy and immunofluorescence showed that this scaffold was organized as in the intact epithelium. Immunoblots demonstrate that vimentin, cytokeratins, desmosomal proteins, and a 52,000-mol-wt nuclear matrix protein were found almost exclusively in the NM-IF scaffold. Vimentin was largely perinuclear while the cytokeratins were localized at the cell borders. The 52,000-mol-wt nuclear matrix protein was confined to the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26147079','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26147079"><span>Small-scale <span class="hlt">filament</span> eruptions as the driver of X-ray jets in solar coronal holes.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Sterling, Alphonse C; Moore, Ronald L; Falconer, David A; Adams, Mitzi</p> <p>2015-07-23</p> <p>Solar X-ray jets are thought to be made by a burst of reconnection of closed magnetic field at the base of a jet with ambient open field. In the accepted version of the 'emerging-flux' model, such a reconnection occurs at a plasma <span class="hlt">current</span> <span class="hlt">sheet</span> between the open field and the emerging closed field, and also forms a localized X-ray brightening that is usually observed at the edge of the jet's base. Here we report high-resolution X-ray and extreme-ultraviolet observations of 20 randomly selected X-ray jets that form in coronal holes at the Sun's poles. In each jet, contrary to the emerging-flux model, a miniature version of the <span class="hlt">filament</span> eruptions that initiate coronal mass ejections drives the jet-producing reconnection. The X-ray bright point occurs by reconnection of the 'legs' of the minifilament-carrying erupting closed field, analogous to the formation of solar flares in larger-scale eruptions. Previous observations have found that some jets are driven by base-field eruptions, but only one such study, of only one jet, provisionally questioned the emerging-flux model. Our observations support the view that solar <span class="hlt">filament</span> eruptions are formed by a fundamental explosive magnetic process that occurs on a vast range of scales, from the biggest mass ejections and flare eruptions down to X-ray jets, and perhaps even down to smaller jets that may power coronal heating. A similar scenario has previously been suggested, but was inferred from different observations and based on a different origin of the erupting minifilament.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PhPl...24c2706K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PhPl...24c2706K"><span><span class="hlt">Filamentation</span> in the pinched column of the dense plasma focus</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kubes, P.; Paduch, M.; Cikhardt, J.; Cikhardtova, B.; Klir, D.; Kravarik, J.; Rezac, K.; Zielinska, E.; Sadowski, M. J.; Szymaszek, A.; Tomaszewski, K.; Zaloga, D.</p> <p>2017-03-01</p> <p>The paper describes the filamentary structure observed in the high-energy ultraviolet radiation for discharges performed at the hydrogen- or deuterium-filling and at the puffing of hydrogen, deuterium or helium, in a mega-ampere dense plasma-focus facility. The lifetime of this structure overcomes 50 ns. These <span class="hlt">filaments</span> connect the surface of a pinched column with internal plasmoids formed at different combinations of filling and puffing gases and they should transport some <span class="hlt">current</span> and plasma. During all the investigated deuterium shots, the fusion-produced neutrons were recorded. Therefore, deuterons should be present in the region of their acceleration, independent of the applied puffing of the gas. Simultaneously with the observed <span class="hlt">filaments</span>, inside the dense plasma column small plasma-balls of mm-dimensions were observed, which had a similar lifetime (longer than the relaxation time) and quasi-stationary positions in the discharge volume. The observed <span class="hlt">filaments</span> and balls might be a manifestation of the (i) discrete spatial structure of the <span class="hlt">current</span> flowing through and around the dense plasma column and (ii) transport of the plasma from external layers to the central region. Their formation and visualization were easier due to the application of air admixtures in the puffed gas.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18186940','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18186940"><span>Characterization of a <span class="hlt">filamentous</span> biofilm community established in a cellulose-fed microbial fuel cell.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ishii, Shun'ichi; Shimoyama, Takefumi; Hotta, Yasuaki; Watanabe, Kazuya</p> <p>2008-01-10</p> <p>Microbial fuel cells (MFCs) are devices that exploit microorganisms to generate electric power from organic matter. Despite the development of efficient MFC reactors, the microbiology of electricity generation remains to be sufficiently understood. A laboratory-scale two-chamber microbial fuel cell (MFC) was inoculated with rice paddy field soil and fed cellulose as the carbon and energy source. Electricity-generating microorganisms were enriched by subculturing biofilms that attached onto anode electrodes. An electric <span class="hlt">current</span> of 0.2 mA was generated from the first enrichment culture, and ratios of the major metabolites (e.g., electric <span class="hlt">current</span>, methane and acetate) became stable after the forth enrichment. In order to investigate the electrogenic microbial community in the anode biofilm, it was morphologically analyzed by electron microscopy, and community members were phylogenetically identified by 16S rRNA gene clone-library analyses. Electron microscopy revealed that <span class="hlt">filamentous</span> cells and rod-shaped cells with prosthecae-like <span class="hlt">filamentous</span> appendages were abundantly present in the biofilm. <span class="hlt">Filamentous</span> cells and appendages were interconnected via thin <span class="hlt">filaments</span>. The clone library analyses frequently detected phylotypes affiliated with Clostridiales, Chloroflexi, Rhizobiales and Methanobacterium. Fluorescence in-situ hybridization revealed that the Rhizobiales population represented rod-shaped cells with <span class="hlt">filamentous</span> appendages and constituted over 30% of the total population. Bacteria affiliated with the Rhizobiales constituted the major population in the cellulose-fed MFC and exhibited unique morphology with <span class="hlt">filamentous</span> appendages. They are considered to play important roles in the cellulose-degrading electrogenic community.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2254626','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2254626"><span>Characterization of a <span class="hlt">filamentous</span> biofilm community established in a cellulose-fed microbial fuel cell</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Ishii, Shun'ichi; Shimoyama, Takefumi; Hotta, Yasuaki; Watanabe, Kazuya</p> <p>2008-01-01</p> <p>Background Microbial fuel cells (MFCs) are devices that exploit microorganisms to generate electric power from organic matter. Despite the development of efficient MFC reactors, the microbiology of electricity generation remains to be sufficiently understood. Results A laboratory-scale two-chamber microbial fuel cell (MFC) was inoculated with rice paddy field soil and fed cellulose as the carbon and energy source. Electricity-generating microorganisms were enriched by subculturing biofilms that attached onto anode electrodes. An electric <span class="hlt">current</span> of 0.2 mA was generated from the first enrichment culture, and ratios of the major metabolites (e.g., electric <span class="hlt">current</span>, methane and acetate) became stable after the forth enrichment. In order to investigate the electrogenic microbial community in the anode biofilm, it was morphologically analyzed by electron microscopy, and community members were phylogenetically identified by 16S rRNA gene clone-library analyses. Electron microscopy revealed that <span class="hlt">filamentous</span> cells and rod-shaped cells with prosthecae-like <span class="hlt">filamentous</span> appendages were abundantly present in the biofilm. <span class="hlt">Filamentous</span> cells and appendages were interconnected via thin <span class="hlt">filaments</span>. The clone library analyses frequently detected phylotypes affiliated with Clostridiales, Chloroflexi, Rhizobiales and Methanobacterium. Fluorescence in-situ hybridization revealed that the Rhizobiales population represented rod-shaped cells with <span class="hlt">filamentous</span> appendages and constituted over 30% of the total population. Conclusion Bacteria affiliated with the Rhizobiales constituted the major population in the cellulose-fed MFC and exhibited unique morphology with <span class="hlt">filamentous</span> appendages. They are considered to play important roles in the cellulose-degrading electrogenic community. PMID:18186940</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17080728','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17080728"><span>Ultrastructural characteristics of tau <span class="hlt">filaments</span> in tauopathies: immuno-electron microscopic demonstration of tau <span class="hlt">filaments</span> in tauopathies.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Arima, Kunimasa</p> <p>2006-10-01</p> <p>The microtubule-associated protein tau aggregates into <span class="hlt">filaments</span> in the form of neurofibrillary tangles, neuropil threads and argyrophilic grains in neurons, in the form of variable astrocytic tangles in astrocytes and in the form of coiled bodies and argyrophilic threads in oligodendrocytes. These tau <span class="hlt">filaments</span> may be classified into two types, straight <span class="hlt">filaments</span> or tubules with 9-18 nm diameters and "twisted ribbons" composed of two parallel aligned components. In the same disease, the fine structure of tau <span class="hlt">filaments</span> in glial cells roughly resembles that in neurons. In sporadic tauopathies, individual tau <span class="hlt">filaments</span> show characteristic sizes, shapes and arrangements, and therefore contribute to neuropathologic differential diagnosis. In frontotemporal dementias caused by tau gene mutations, variable <span class="hlt">filamentous</span> profiles were observed in association with mutation sites and insoluble tau isoforms, including straight <span class="hlt">filaments</span> or tubules, paired helical <span class="hlt">filament</span>-like <span class="hlt">filaments</span>, and twisted ribbons. Pre-embedding immunoelectron microscopic studies were carried out using anti-3-repeat tau and anti-4-repeat tau specific antibodies, RD3 and RD4. Straight tubules in neuronal and astrocytic Pick bodies were immunolabeled by the anti-3-repeat tau antibody. The anti-4-repeat tau antibody recognized abnormal tubules comprising neurofibrillary tangles, coiled bodies and argyrophilic threads in progressive supranuclear palsy (PSP) and corticobasal degeneration. In the pre-embedding immunoelectron microscopic study using the phosphorylated tau AT8 antibody, tuft-shaped astrocytes of PSP were found to be composed of bundles of abnormal tubules in processes and perikarya of protoplasmic astrocytes. In this study, the 3-repeat tau or 4-repeat tau epitope was detected in situ at the ultrastructural level in abnormal tubules in representative pathological lesions in Pick's disease, PSP and corticobasal degeneration.</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('https://www.osti.gov/biblio/22667191-formation-inverse-shaped-active-region-filament-driven-sunspot-motion-magnetic-reconnection','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22667191-formation-inverse-shaped-active-region-filament-driven-sunspot-motion-magnetic-reconnection"><span>THE FORMATION OF AN INVERSE S-SHAPED ACTIVE-REGION <span class="hlt">FILAMENT</span> DRIVEN BY SUNSPOT MOTION AND 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>Yan, X. L.; Xue, Z. K.; Wang, J. C.</p> <p>2016-11-20</p> <p>We present a detailed study of the formation of an inverse S-shaped <span class="hlt">filament</span> prior to its eruption in active region NOAA 11884 from 2013 October 31 to November 2. In the initial stage, clockwise rotation of a small positive sunspot around the main negative trailing sunspot formed a curved <span class="hlt">filament</span>. Then the small sunspot cancelled with the negative magnetic flux to create a longer active-region <span class="hlt">filament</span> with an inverse S-shape. At the cancellation site a brightening was observed in UV and EUV images and bright material was transferred to the <span class="hlt">filament</span>. Later the <span class="hlt">filament</span> erupted after cancellation of two oppositemore » polarities below the upper part of the <span class="hlt">filament</span>. Nonlinear force-free field extrapolation of vector photospheric fields suggests that the <span class="hlt">filament</span> may have a twisted structure, but this cannot be confirmed from the <span class="hlt">current</span> observations.« 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('http://adsabs.harvard.edu/abs/2016PhLA..380...88S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PhLA..380...88S"><span>Boolean gates on actin <span class="hlt">filaments</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Siccardi, Stefano; Tuszynski, Jack A.; Adamatzky, Andrew</p> <p>2016-01-01</p> <p>Actin is a globular protein which forms long polar <span class="hlt">filaments</span> in the eukaryotic cytoskeleton. Actin networks play a key role in cell mechanics and cell motility. They have also been implicated in information transmission and processing, memory and learning in neuronal cells. The actin <span class="hlt">filaments</span> have been shown to support propagation of voltage pulses. Here we apply a coupled nonlinear transmission line model of actin <span class="hlt">filaments</span> to study interactions between voltage pulses. To represent digital information we assign a logical TRUTH value to the presence of a voltage pulse in a given location of the actin <span class="hlt">filament</span>, and FALSE to the pulse's absence, so that information flows along the <span class="hlt">filament</span> with pulse transmission. When two pulses, representing Boolean values of input variables, interact, then they can facilitate or inhibit further propagation of each other. We explore this phenomenon to construct Boolean logical gates and a one-bit half-adder with interacting voltage pulses. We discuss implications of these findings on cellular process and technological applications.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015NatMa..14..583W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015NatMa..14..583W"><span>Solid friction between soft <span class="hlt">filaments</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ward, Andrew; Hilitski, Feodor; Schwenger, Walter; Welch, David; Lau, A. W. C.; Vitelli, Vincenzo; Mahadevan, L.; Dogic, Zvonimir</p> <p>2015-06-01</p> <p>Any macroscopic deformation of a <span class="hlt">filamentous</span> bundle is necessarily accompanied by local sliding and/or stretching of the constituent <span class="hlt">filaments</span>. Yet the nature of the sliding friction between two aligned <span class="hlt">filaments</span> interacting through multiple contacts remains largely unexplored. Here, by directly measuring the sliding forces between two bundled F-actin <span class="hlt">filaments</span>, we show that these frictional forces are unexpectedly large, scale logarithmically with sliding velocity as in solid-like friction, and exhibit complex dependence on the filaments’ overlap length. We also show that a reduction of the frictional force by orders of magnitude, associated with a transition from solid-like friction to Stokes’s drag, can be induced by coating F-actin with polymeric brushes. Furthermore, we observe similar transitions in <span class="hlt">filamentous</span> microtubules and bacterial flagella. Our findings demonstrate how altering a filament’s elasticity, structure and interactions can be used to engineer interfilament friction and thus tune the properties of fibrous composite materials.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1347136-solid-friction-between-soft-filaments','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1347136-solid-friction-between-soft-filaments"><span>Solid friction between soft <span class="hlt">filaments</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Ward, Andrew; Hilitski, Feodor; Schwenger, Walter; ...</p> <p>2015-03-02</p> <p>Any macroscopic deformation of a <span class="hlt">filamentous</span> bundle is necessarily accompanied by local sliding and/or stretching of the constituent <span class="hlt">filaments</span>. Yet the nature of the sliding friction between two aligned <span class="hlt">filaments</span> interacting through multiple contacts remains largely unexplored. Here, by directly measuring the sliding forces between two bundled F-actin <span class="hlt">filaments</span>, we show that these frictional forces are unexpectedly large, scale logarithmically with sliding velocity as in solid-like friction, and exhibit complex dependence on the filaments’ overlap length. We also show that a reduction of the frictional force by orders of magnitude, associated with a transition from solid-like friction to Stokes’s drag,more » can be induced by coating F-actin with polymeric brushes. Furthermore, we observe similar transitions in <span class="hlt">filamentous</span> microtubules and bacterial flagella. In conclusion, our findings demonstrate how altering a filament’s elasticity, structure and interactions can be used to engineer interfilament friction and thus tune the properties of fibrous composite materials.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015MNRAS.453L.108L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015MNRAS.453L.108L"><span><span class="hlt">Filaments</span> from the galaxy distribution and from the velocity field in the local universe</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Libeskind, Noam I.; Tempel, Elmo; Hoffman, Yehuda; Tully, R. Brent; Courtois, Hélène</p> <p>2015-10-01</p> <p>The cosmic web that characterizes the large-scale structure of the Universe can be quantified by a variety of methods. For example, large redshift surveys can be used in combination with point process algorithms to extract long curvilinear <span class="hlt">filaments</span> in the galaxy distribution. Alternatively, given a full 3D reconstruction of the velocity field, kinematic techniques can be used to decompose the web into voids, <span class="hlt">sheets</span>, <span class="hlt">filaments</span> and knots. In this Letter, we look at how two such algorithms - the Bisous model and the velocity shear web - compare with each other in the local Universe (within 100 Mpc), finding good agreement. This is both remarkable and comforting, given that the two methods are radically different in ideology and applied to completely independent and different data sets. Unsurprisingly, the methods are in better agreement when applied to unbiased and complete data sets, like cosmological simulations, than when applied to observational samples. We conclude that more observational data is needed to improve on these methods, but that both methods are most likely properly tracing the underlying distribution of matter in the Universe.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/15379969','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/15379969"><span>Electron microscopic observations of human sperm whole-mounts after extraction for nuclear matrix and intermediate <span class="hlt">filaments</span> (NM-IF).</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Markova, Maya Dyankova</p> <p>2004-10-01</p> <p>The extraction for nuclear matrix and intermediate <span class="hlt">filaments</span> (NM-IF) is used to reveal, isolate and study these highly resistant structures in different cell types. We applied for the first time this chemical dissection to human spermatozoa and observed them as whole-mounts by unembedded electron microscopy. The general appearance of NM-IF extracted sperm cells was preserved, showing the intermediate <span class="hlt">filament</span>-like properties of their cytoskeletal components. In most heads, a network was observed in subacrosomal position, consisting of hubs interconnected by <span class="hlt">filaments</span>. It seemed to be overlaid on another, finer network. The neck retained its integrity, allowing observations of the three-dimensional structure of the segmented columns. More distally, axoneme and outer dense fibres were covered by submitochondrial cytoskeleton in the middle piece and fibrous sheath in the principal piece, with the annulus usually detached from the fibrous sheath. End piece microtubules were retained in most cells and showed a tendency of cohesion, remaining in a parallel bundle or forming flat <span class="hlt">sheets</span>. In conclusion, our results provided additional structural details of human sperm cytoskeleton and demonstrated the advantages of combining different methodological approaches in ultrastructural research.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19870011450','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19870011450"><span>Recent observations of the formation of <span class="hlt">filaments</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Martin, Sara F.</p> <p>1986-01-01</p> <p>Two examples of the formation of small <span class="hlt">filaments</span> in H alpha are described and illustrated. In both cases, the formation is seen to be the spontaneous appearance of strands of absorbing mass that evolve from no previous structure. The initial development of the <span class="hlt">filaments</span> appears to consist of the accumulation of these absorptive strands along approximately parallel paths in a channel between large-scale, opposite polarity magnetic fields on either side of the <span class="hlt">filaments</span>. The strands exhibit continuous changes in shape and degree of absorption which can be due to successive condensations resulting in new strands, mass motions within the strands, and outflow of the mass from the strands. For at least several hours before the formation of both <span class="hlt">filaments</span>, small-scale fragments of opposite polarity, line-of-sight magnetic flux adjacent to or immediately below the <span class="hlt">filaments</span>, and at the ends of the <span class="hlt">filaments</span>, were cancelling. This type of magnetic flux disappearance continued during the development of the <span class="hlt">filaments</span> and is commonly observed in association with established <span class="hlt">filaments</span>. Cancellation is interpreted as an important evolutionary change in the magnetic field that can lead to configurations suitable for the formation of <span class="hlt">filaments</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22663785-interaction-two-filaments-long-filament-channel-associated-twin-coronal-mass-ejections','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22663785-interaction-two-filaments-long-filament-channel-associated-twin-coronal-mass-ejections"><span>Interaction of Two <span class="hlt">Filaments</span> in a Long <span class="hlt">Filament</span> Channel Associated with Twin Coronal Mass Ejections</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>Zheng, Ruisheng; Chen, Yao; Wang, Bing</p> <p></p> <p>Using the high-quality observations of the Solar Dynamics Observatory , we present the interaction of two <span class="hlt">filaments</span> (F1 and F2) in a long <span class="hlt">filament</span> channel associated with twin coronal mass ejections (CMEs) on 2016 January 26. Before the eruption, a sequence of rapid cancellation and emergence of the magnetic flux has been observed, which likely triggered the ascending of the west <span class="hlt">filament</span> (F1). The east footpoints of rising F1 moved toward the east far end of the <span class="hlt">filament</span> channel, accompanied by post-eruption loops and flare ribbons. This likely indicated a large-scale eruption involving the long <span class="hlt">filament</span> channel, which resulted frommore » the interaction between F1 and the east <span class="hlt">filament</span> (F2). Some bright plasma flew over F2, and F2 stayed at rest during the eruption, likely due to the confinement of its overlying lower magnetic field. Interestingly, the impulsive F1 pushed its overlying magnetic arcades to form the first CME, and F1 finally evolved into the second CME after the collision with the nearby coronal hole. We suggest that the interaction of F1 and the overlying magnetic field of F2 led to the merging reconnection that forms a longer eruptive <span class="hlt">filament</span> loop. Our results also provide a possible picture of the origin of twin CMEs and show that the large-scale magnetic topology of the coronal hole is important for the eventual propagation direction of CMEs.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3274092','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3274092"><span>Femtosecond Laser <span class="hlt">Filamentation</span> for Atmospheric Sensing</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Xu, Huai Liang; Chin, See Leang</p> <p>2011-01-01</p> <p>Powerful femtosecond laser pulses propagating in transparent materials result in the formation of self-guided structures called <span class="hlt">filaments</span>. Such <span class="hlt">filamentation</span> in air can be controlled to occur at a distance as far as a few kilometers, making it ideally suited for remote sensing of pollutants in the atmosphere. On the one hand, the high intensity inside the <span class="hlt">filaments</span> can induce the fragmentation of all matters in the path of <span class="hlt">filaments</span>, resulting in the emission of characteristic fluorescence spectra (fingerprints) from the excited fragments, which can be used for the identification of various substances including chemical and biological species. On the other hand, along with the femtosecond laser <span class="hlt">filamentation</span>, white-light supercontinuum emission in the infrared to UV range is generated, which can be used as an ideal light source for absorption Lidar. In this paper, we present an overview of recent progress concerning remote sensing of the atmosphere using femtosecond laser <span class="hlt">filamentation</span>. PMID:22346566</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018ApJ...858...64R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018ApJ...858...64R"><span>Powering of Hα <span class="hlt">Filaments</span> by Cosmic Rays</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ruszkowski, Mateusz; Yang, H.-Y. Karen; Reynolds, Christopher S.</p> <p>2018-05-01</p> <p>Cluster cool cores possess networks of line-emitting <span class="hlt">filaments</span>. These <span class="hlt">filaments</span> are thought to originate via uplift of cold gas from cluster centers by buoyant active galactic nuclei (AGNs) bubbles, or via local thermal instability in the hot intracluster medium (ICM). Therefore, the <span class="hlt">filaments</span> are either the signatures of AGN feedback or feeding of supermassive black holes. Despite being characterized by very short cooling times, the <span class="hlt">filaments</span> are significant Hα emitters, which suggests that some process continuously powers these structures. Many cool cores host diffuse radio mini halos and AGN injecting radio plasma, suggesting that cosmic rays (CRs) and magnetic fields are present in the ICM. We argue that the excitation of Alfvén waves by CR streaming, and the replenishment of CR energy via accretion onto the <span class="hlt">filaments</span> of high-plasma-β ICM characterized by low CR pressure support, can provide the adequate amount of heating to power and sustain the emission from these <span class="hlt">filaments</span>. This mechanism does not require the CRs to penetrate the <span class="hlt">filaments</span>, even if the <span class="hlt">filaments</span> are magnetically isolated from the ambient ICM, and it may operate irrespectively of whether the <span class="hlt">filaments</span> are dredged up from the center or form in situ in the ICM. This picture is qualitatively consistent with non-thermal line ratios seen in the cold <span class="hlt">filaments</span>. Future X-ray observations of the iron line complex with XARM, Lynx, or Athena could help to test this model by providing constraints on the amount of CRs in the hot plasma that is cooling and accreting onto the <span class="hlt">filaments</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_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('http://adsabs.harvard.edu/abs/2000SuScT..13..405T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2000SuScT..13..405T"><span>Some factors determining the effective resistance between strands in flat cables (or superconducting <span class="hlt">filaments</span> in tapes)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Takács, S.; Iwakuma, M.; Funaki, K.</p> <p>2000-04-01</p> <p>Two effects are considered which can influence the effective resistance between crossing strands on flat cables or <span class="hlt">filaments</span> in twisted tapes. As analogous cases, the one-layer Rutherford-type cable with classical superconductors and the tapes with twisted BSCCO <span class="hlt">filaments</span> in a silver matrix in perpendicular magnetic fields are considered as a model. At first, the amount of the central core between the strands and the silver matrix between the <span class="hlt">filaments</span> increases the effective conductance compared with the direct <span class="hlt">current</span> paths, which is supposed to be proportional to the touching area of <span class="hlt">filaments</span>. The increase factor is about two and can be easily suppressed by other effects, such as the contact resistance between the superconductor and the matrix. However, due to the strong anisotropy of critical parameters for high temperature superconductors, this effect can partially compensate the influence of the usually weaker critical <span class="hlt">current</span> density perpendicular to the tape. The second effect is connected with the existence of the induced voltage between any points of crossing <span class="hlt">filaments</span>. This leads to an additional effective conductance, proportional to the square of the total number of the <span class="hlt">filaments</span>. This contribution is prevailing for the anisotropic superconductors. Therefore, to obtain low ac coupling losses in BSCCO tapes, structures with smaller <span class="hlt">filament</span> number are required. This case is analogous to round structures, leading to ac losses proportional to the square of the layer number in the field direction.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22365520-solar-filament-material-oscillations-drainage-before-eruption','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22365520-solar-filament-material-oscillations-drainage-before-eruption"><span>Solar <span class="hlt">filament</span> material oscillations and drainage before eruption</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>Bi, Yi; Jiang, Yunchun; Yang, Jiayan</p> <p></p> <p>Both large-amplitude longitudinal (LAL) oscillations and material drainage in a solar <span class="hlt">filament</span> are associated with the flow of material along the <span class="hlt">filament</span> axis, often followed by an eruption. However, the relationship between these two motions and a subsequent eruption event is poorly understood. We analyze a <span class="hlt">filament</span> eruption using EUV imaging data captured by the Atmospheric Imaging Array on board the Solar Dynamics Observatory and the Hα images from the Global Oscillation Network Group. Hours before the eruption, the <span class="hlt">filament</span> was activated, with one of its legs undergoing a slow rising motion. The asymmetric activation inclined the <span class="hlt">filament</span> relative tomore » the solar surface. After the active phase, LAL oscillations were observed in the inclined <span class="hlt">filament</span>. The oscillation period increased slightly over time, which may suggest that the magnetic fields supporting the <span class="hlt">filament</span> evolve to be flatter during the slow rising phase. After the oscillations, a significant amount of <span class="hlt">filament</span> material was drained toward one <span class="hlt">filament</span> endpoint, followed immediately by the violent eruption of the <span class="hlt">filament</span>. The material drainage may further support the change in magnetic topology prior to the eruption. Moreover, we suggest that the <span class="hlt">filament</span> material drainage could play a role in the transition from a slow to a fast rise of the erupting <span class="hlt">filament</span>.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2116036','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2116036"><span>Core <span class="hlt">filaments</span> of the nuclear matrix</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>1990-01-01</p> <p>The nuclear matrix is concealed by a much larger mass of chromatin, which can be removed selectively by digesting nuclei with DNase I followed by elution of chromatin with 0.25 M ammonium sulfate. This mild procedure removes chromatin almost completely and preserves nuclear matrix morphology. The complete nuclear matrix consists of a nuclear lamina with an interior matrix composed of thick, polymorphic fibers and large masses that resemble remnant nucleoli. Further extraction of the nuclear matrices of HeLa or MCF-7 cells with 2 M sodium chloride uncovered a network of core <span class="hlt">filaments</span>. A few dark masses remained enmeshed in the <span class="hlt">filament</span> network and may be remnants of the nuclear matrix thick fibers and nucleoli. The highly branched core <span class="hlt">filaments</span> had diameters of 9 and 13 nm measured relative to the intermediate <span class="hlt">filaments</span>. They may serve as the core structure around which the matrix is constructed. The core <span class="hlt">filaments</span> retained 70% of nuclear RNA. This RNA consisted both of ribosomal RNA precursors and of very high molecular weight hnRNA with a modal size of 20 kb. Treatment with RNase A removed the core <span class="hlt">filaments</span>. When 2 M sodium chloride was used directly to remove chromatin after DNase I digestion without a preceding 0.25 M ammonium sulfate extraction, the core <span class="hlt">filaments</span> were not revealed. Instead, the nuclear interior was filled with amorphous masses that may cover the <span class="hlt">filaments</span>. This reflected a requirement for a stepwise increase in ionic strength because gradual addition of sodium chloride to a final concentration of 2 M without an 0.25 M ammonium sulfate extraction uncovered core <span class="hlt">filaments</span>. PMID:2307700</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/2018PhyEd..53c5018L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018PhyEd..53c5018L"><span>In search of the dimensions of an incandescent light bulb <span class="hlt">filament</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ladino, Luis A.; Rondón, Hermilda S.</p> <p>2018-05-01</p> <p>The purpose of this paper is to present and discuss an alternative solution to an experimental problem given to high school students in the XXII Ibero-American Physics Olympiad held by Colombia this year. From the measurements of electric <span class="hlt">current</span> and potential difference across a small tungsten <span class="hlt">filament</span> lamp students should find the dimensions of its <span class="hlt">filament</span>. The results obtained are compared with the ones measured directly. This challenging and low-cost experiment can be easily implemented and carried out in any introductory physics laboratory courses.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016RuPhJ..58.1581A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016RuPhJ..58.1581A"><span>Multiple <span class="hlt">Filamentation</span> of Laser Pulses in a Glass</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Apeksimov, D. V.; Bukin, O. A.; Golik, S. S.; Zemlyanov, A. A.; Iglakova, A. N.; Kabanov, A. M.; Kuchinskaya, O. I.; Matvienko, G. G.; Oshlakov, V. K.; Petrov, A. V.; Sokolova, E. B.</p> <p>2016-03-01</p> <p>Results are presented of experiments on investigation of the spatial characteristics of multi-<span class="hlt">filamentation</span> region of giga- and terawatt pulses of a Ti:sapphire laser in a glass. Dependences are obtained of the coordinate of the beginning of <span class="hlt">filamentation</span> region, number of <span class="hlt">filaments</span>, their distribution along the laser beam axis, and length of <span class="hlt">filaments</span> on the pulse power. It is shown that with increasing radiation power, the number of <span class="hlt">filaments</span> in the multi-<span class="hlt">filamentation</span> region decreases, whereas the <span class="hlt">filament</span> diameter has a quasiconstant value for all powers realized in the experiments. It is shown that as a certain power of the laser pulse with Gauss energy density distribution is reached, the <span class="hlt">filamentation</span> region acquires the shape of a hollow cone with apex directed toward the radiation source.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25492418','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25492418"><span><span class="hlt">Current</span> state and future perspectives of loop-mediated isothermal amplification (LAMP)-based diagnosis of <span class="hlt">filamentous</span> fungi and yeasts.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Niessen, Ludwig</p> <p>2015-01-01</p> <p>Loop-mediated isothermal amplification is a rather novel method of enzymatic deoxyribonucleic acid amplification which can be applied for the diagnosis of viruses, bacteria, and fungi. Although firmly established in viral and bacterial diagnosis, the technology has only recently been applied to a noteworthy number of species in the <span class="hlt">filamentous</span> fungi and yeasts. The <span class="hlt">current</span> review gives an overview of the literature so far published on the topic by discussing the different groups of fungal organisms to which the method has been applied. Moreover, the method is described in detail as well as the different possibilities available for signal detection and quantification and sample preparation. Future perspective of loop-mediated isothermal amplification-based assays is discussed in the light of applicability for fungal diagnostics.</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('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 tail passes in the earlier interval, during which prominent PPO-related tail 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('http://adsabs.harvard.edu/abs/2017ApJ...835...94O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017ApJ...835...94O"><span>Chirality and Magnetic Configurations of Solar <span class="hlt">Filaments</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ouyang, Y.; Zhou, Y. H.; Chen, P. F.; Fang, C.</p> <p>2017-01-01</p> <p>It has been revealed that the magnetic topology in the solar atmosphere displays hemispheric preference, I.e., helicity is mainly negative/positive in the northern/southern hemispheres, respectively. However, the strength of the hemispheric rule and its cyclic variation are controversial. In this paper, we apply a new method based on the <span class="hlt">filament</span> drainage to 571 erupting <span class="hlt">filaments</span> from 2010 May to 2015 December in order to determine the <span class="hlt">filament</span> chirality and its hemispheric preference. It is found that 91.6% of our sample of erupting <span class="hlt">filaments</span> follows the hemispheric rule of helicity sign. It is also found that the strength of the hemispheric preference of the quiescent <span class="hlt">filaments</span> decreases slightly from ˜97% in the rising phase to ˜85% in the declining phase of solar cycle 24, whereas the strength of the intermediate <span class="hlt">filaments</span> keeps a high value around 96 ± 4% at all times. Only the active-region <span class="hlt">filaments</span> show significant variations. Their strength of the hemispheric rule rises from ˜63% to ˜95% in the rising phase, and keeps a high value of 82% ± 5% during the declining phase. Furthermore, during a half-year period around the solar maximum, their hemispheric preference totally vanishes. Additionally, we also diagnose the magnetic configurations of the <span class="hlt">filaments</span> based on our indirect method and find that in our sample of erupting events, 89% are inverse-polarity <span class="hlt">filaments</span> with a flux rope magnetic configuration, whereas 11% are normal-polarity <span class="hlt">filaments</span> with a sheared arcade configuration.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25987265','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25987265"><span>Fabrication of continuous electrospun <span class="hlt">filaments</span> with potential for use as medical fibres.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Mouthuy, Pierre-Alexis; Zargar, Nasim; Hakimi, Osnat; Lostis, Emilie; Carr, Andrew</p> <p>2015-05-19</p> <p>Soft tissue injuries represent a substantial and growing social and economic burden. Medical fibres are commonly used to repair these injuries during surgery. Patient's outcomes are, however, not promising with around 40% of surgical repairs failing within the first few months after surgery due to poor tissue regeneration. The application of nanofibrous <span class="hlt">filaments</span> and yarns as medical fibres and scaffolds has been suggested to improve soft tissue regeneration and enhance the quality of the repair. However, due to a lack of robustness and reliability of the <span class="hlt">current</span> fabrication methods, continuous nanofibrous <span class="hlt">filaments</span> cannot be manufactured and scaled up in industrial settings and are not <span class="hlt">currently</span> available for clinical use. We have developed a robust and automated method that enables the manufacture of continuous electrospun <span class="hlt">filaments</span> and which has the potential to be integrated into existing textile production lines. The technology uses a wire guide to form submicrofibres in a dense, narrow mesh which can be detached as a long and continuous thread. The thread can then be stretched and used to create multifilament yarns which can imitate the hierarchical architecture of tissues such as tendons and ligaments. Electrospun polydioxanone yarns produced by this method showed improved cellular proliferation and adhesion when compared to medical monofilament fibres in <span class="hlt">current</span> clinical use. In vivo, the electrospun yarns showed a good safety profile with mild foreign body reaction and complete degradation within 5 months after implantation. These results suggest that this <span class="hlt">filament</span> collection method has the potential to become a useful platform for the fabrication of future medical textiles.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22661096-measuring-filament-orientation-new-quantitative-local-approach','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22661096-measuring-filament-orientation-new-quantitative-local-approach"><span>Measuring <span class="hlt">Filament</span> Orientation: A New Quantitative, Local Approach</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>Green, C.-E.; Cunningham, M. R.; Jones, P. A.</p> <p></p> <p>The relative orientation between filamentary structures in molecular clouds and the ambient magnetic field provides insight into <span class="hlt">filament</span> formation and stability. To calculate the relative orientation, a measurement of <span class="hlt">filament</span> orientation is first required. We propose a new method to calculate the orientation of the one-pixel-wide <span class="hlt">filament</span> skeleton that is output by <span class="hlt">filament</span> identification algorithms such as filfinder. We derive the local <span class="hlt">filament</span> orientation from the direction of the intensity gradient in the skeleton image using the Sobel filter and a few simple post-processing steps. We call this the “Sobel-gradient method.” The resulting <span class="hlt">filament</span> orientation map can be compared quantitativelymore » on a local scale with the magnetic field orientation map to then find the relative orientation of the <span class="hlt">filament</span> with respect to the magnetic field at each point along the <span class="hlt">filament</span>. It can also be used for constructing radial profiles for <span class="hlt">filament</span> width fitting. The proposed method facilitates automation in analyses of <span class="hlt">filament</span> skeletons, which is imperative in this era of “big data.”.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017ApJS..232....6G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017ApJS..232....6G"><span>Measuring <span class="hlt">Filament</span> Orientation: A New Quantitative, Local Approach</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Green, C.-E.; Dawson, J. R.; Cunningham, M. R.; Jones, P. A.; Novak, G.; Fissel, L. M.</p> <p>2017-09-01</p> <p>The relative orientation between filamentary structures in molecular clouds and the ambient magnetic field provides insight into <span class="hlt">filament</span> formation and stability. To calculate the relative orientation, a measurement of <span class="hlt">filament</span> orientation is first required. We propose a new method to calculate the orientation of the one-pixel-wide <span class="hlt">filament</span> skeleton that is output by <span class="hlt">filament</span> identification algorithms such as filfinder. We derive the local <span class="hlt">filament</span> orientation from the direction of the intensity gradient in the skeleton image using the Sobel filter and a few simple post-processing steps. We call this the “Sobel-gradient method.” The resulting <span class="hlt">filament</span> orientation map can be compared quantitatively on a local scale with the magnetic field orientation map to then find the relative orientation of the <span class="hlt">filament</span> with respect to the magnetic field at each point along the <span class="hlt">filament</span>. It can also be used for constructing radial profiles for <span class="hlt">filament</span> width fitting. The proposed method facilitates automation in analyses of <span class="hlt">filament</span> skeletons, which is imperative in this era of “big data.”</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016Cryo...73...14W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016Cryo...73...14W"><span>Mechanical behaviors of multi-<span class="hlt">filament</span> twist superconducting strand under tensile and cyclic loading</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, Xu; Li, Yingxu; Gao, Yuanwen</p> <p>2016-01-01</p> <p>The superconducting strand, serving as the basic unit cell of the cable-in-conduit-conductors (CICCs), is a typical multi-<span class="hlt">filament</span> twist composite which is always subjected to a cyclic loading under the operating condition. Meanwhile, the superconducting material Nb3Sn in the strand is sensitive to strain frequently relating to the performance degradation of the superconductivity. Therefore, a comprehensive study on the mechanical behavior of the strand helps understanding the superconducting performance of the strained Nb3Sn strands. To address this issue, taking the LMI (internal tin) strand as an example, a three-dimensional structural finite element model, named as the Multi-<span class="hlt">filament</span> twist model, of the strand with the real configuration of the LMI strand is built to study the influences of the plasticity of the component materials, the twist of the <span class="hlt">filament</span> bundle, the initial thermal residual stress and the breakage and its evolution of the <span class="hlt">filaments</span> on the mechanical behaviors of the strand. The effective properties of superconducting <span class="hlt">filament</span> bundle with random <span class="hlt">filament</span> breakage and its evolution versus strain are obtained based on the damage theory of fiber-reinforced composite materials proposed by Curtin and Zhou. From the calculation results of this model, we find that the occurrence of the hysteresis loop in the cyclic loading curve is determined by the reverse yielding of the elastic-plastic materials in the strand. Both the initial thermal residual stress in the strand and the pitch length of the <span class="hlt">filaments</span> have significant impacts on the axial and hysteretic behaviors of the strand. The damage of the <span class="hlt">filaments</span> also affects the axial mechanical behavior of the strand remarkably at large axial strain. The critical <span class="hlt">current</span> of the strand is calculated by the scaling law with the results of the Multi-<span class="hlt">filament</span> twist model. The predicted results of the Multi-<span class="hlt">filament</span> twist model show an acceptable agreement with the experiment.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006EPJE...20..459K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006EPJE...20..459K"><span>Dynamics and mechanics of motor-<span class="hlt">filament</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>Kruse, K.; Jülicher, F.</p> <p>2006-08-01</p> <p>Motivated by the cytoskeleton of eukaryotic cells, we develop a general framework for describing the large-scale dynamics of an active <span class="hlt">filament</span> network. In the cytoskeleton, active cross-links are formed by motor proteins that are able to induce relative motion between <span class="hlt">filaments</span>. Starting from pair-wise interactions of <span class="hlt">filaments</span> via such active processes, our framework is based on momentum conservation and an analysis of the momentum flux. This allows us to calculate the stresses in the <span class="hlt">filament</span> network generated by the action of motor proteins. We derive effective theories for the <span class="hlt">filament</span> dynamics which can be related to continuum theories of active polar gels. As an example, we discuss the stability of homogenous isotropic <span class="hlt">filament</span> distributions in two spatial dimensions.</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('http://adsabs.harvard.edu/abs/2005JPhy4.127..205C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005JPhy4.127..205C"><span>Laser femtoseconde, <span class="hlt">filamentation</span>, nuage et orage</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Courvoisier, F.; Boutou, V.; Kasparian, J.; Salmon, E.; Méjean, G.; Yu, J.; Wolf, J.-P.</p> <p>2005-06-01</p> <p>Les applications telles que le contrôle de foudre grâce aux <span class="hlt">filaments</span> autoguidés générés par un laser femtoseconde nécessitent de propager un tel <span class="hlt">filament</span> à travers des aérosols de gouttes d'eau. Nous montrons qu'un <span class="hlt">filament</span> survit à son interaction avec une goutte de diamètre comparable au sien (95 μ m), ainsi qu'à des nuages d'épaisseur optique 3,2, soit 5% de transmission. Cette transmission est permise par la présence d'un “bain de photons” autour du <span class="hlt">filament</span>. Ce bain forme un réservoir contenant une part importante de l'énergie du faisceau, en équilibre avec le <span class="hlt">filament</span>, et favorisant son alimentation.</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> </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('http://adsabs.harvard.edu/abs/2013CSR....63...59M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013CSR....63...59M"><span>The circulation dynamics associated with a northern Benguela upwelling <span class="hlt">filament</span> during October 2010</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Muller, Annethea A.; Mohrholz, Volker; Schmidt, Martin</p> <p>2013-07-01</p> <p>Upwelling <span class="hlt">filaments</span>, a common feature in all the major upwelling systems, are also regularly observed in the Benguela upwelling system and are thought to provide an effective mechanism for the exchange of matter between the shelf and the open ocean. The mesoscale dynamics of a northern Benguela upwelling <span class="hlt">filament</span> located at approximately 18.5°S were examined and the associated transport was quantified. The development of the <span class="hlt">filament</span> was tracked using optimal interpolated SST satellite data and two transects were consequently sampled across the feature using a towed undulating CTD (ScanFish). Additional hydrographic, nutrient and biological parameters were investigated at several stations along each transect. Following 7 days of strong upwelling favorable winds, sampling coincided with a period of relative wind relaxation and the <span class="hlt">filament</span> was presumably in a decaying state. The basic mesoscale structure of the investigated <span class="hlt">filament</span> corresponded well to what had previously been described for <span class="hlt">filaments</span> from other eastern boundary <span class="hlt">current</span> systems. The cross-shore transport associated with the <span class="hlt">filament</span> was found to be significantly greater than the integrated Ekman transport in the region. With the combination of the high resolution dataset and a MOM-4 ecosystem model the complex mesoscale flow field associated with the feature could be observed and the counterbalancing onshore transport, associated with subsurface dipole eddies, was revealed within the <span class="hlt">filament</span>. The results further suggest that an interaction between the offshore bending of flow at the Angola-Benguela Front (ABF), the detachment of the strong poleward flow from the coast as the thermal front meanders and the observed dipole eddies may be driving <span class="hlt">filament</span> occurrence in the region off Cape Frio.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22667721-chirality-magnetic-configurations-solar-filaments','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22667721-chirality-magnetic-configurations-solar-filaments"><span>CHIRALITY AND MAGNETIC CONFIGURATIONS OF SOLAR <span class="hlt">FILAMENTS</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>Ouyang, Y.; Zhou, Y. H.; Chen, P. F.</p> <p></p> <p>It has been revealed that the magnetic topology in the solar atmosphere displays hemispheric preference, i.e., helicity is mainly negative/positive in the northern/southern hemispheres, respectively. However, the strength of the hemispheric rule and its cyclic variation are controversial. In this paper, we apply a new method based on the <span class="hlt">filament</span> drainage to 571 erupting <span class="hlt">filaments</span> from 2010 May to 2015 December in order to determine the <span class="hlt">filament</span> chirality and its hemispheric preference. It is found that 91.6% of our sample of erupting <span class="hlt">filaments</span> follows the hemispheric rule of helicity sign. It is also found that the strength of the hemisphericmore » preference of the quiescent <span class="hlt">filaments</span> decreases slightly from ∼97% in the rising phase to ∼85% in the declining phase of solar cycle 24, whereas the strength of the intermediate <span class="hlt">filaments</span> keeps a high value around 96 ± 4% at all times. Only the active-region <span class="hlt">filaments</span> show significant variations. Their strength of the hemispheric rule rises from ∼63% to ∼95% in the rising phase, and keeps a high value of 82% ± 5% during the declining phase. Furthermore, during a half-year period around the solar maximum, their hemispheric preference totally vanishes. Additionally, we also diagnose the magnetic configurations of the <span class="hlt">filaments</span> based on our indirect method and find that in our sample of erupting events, 89% are inverse-polarity <span class="hlt">filaments</span> with a flux rope magnetic configuration, whereas 11% are normal-polarity <span class="hlt">filaments</span> with a sheared arcade configuration.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21893596','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21893596"><span>Cytoskeleton in motion: the dynamics of keratin intermediate <span class="hlt">filaments</span> in epithelia.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Windoffer, Reinhard; Beil, Michael; Magin, Thomas M; Leube, Rudolf E</p> <p>2011-09-05</p> <p>Epithelia are exposed to multiple forms of stress. Keratin intermediate <span class="hlt">filaments</span> are abundant in epithelia and form cytoskeletal networks that contribute to cell type-specific functions, such as adhesion, migration, and metabolism. A perpetual keratin <span class="hlt">filament</span> turnover cycle supports these functions. This multistep process keeps the cytoskeleton in motion, facilitating rapid and protein biosynthesis-independent network remodeling while maintaining an intact network. The <span class="hlt">current</span> challenge is to unravel the molecular mechanisms underlying the regulation of the keratin cycle in relation to actin and microtubule networks and in the context of epithelial tissue function.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3171125','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3171125"><span>Cytoskeleton in motion: the dynamics of keratin intermediate <span class="hlt">filaments</span> in epithelia</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Windoffer, Reinhard; Beil, Michael; Magin, Thomas M.</p> <p>2011-01-01</p> <p>Epithelia are exposed to multiple forms of stress. Keratin intermediate <span class="hlt">filaments</span> are abundant in epithelia and form cytoskeletal networks that contribute to cell type–specific functions, such as adhesion, migration, and metabolism. A perpetual keratin <span class="hlt">filament</span> turnover cycle supports these functions. This multistep process keeps the cytoskeleton in motion, facilitating rapid and protein biosynthesis–independent network remodeling while maintaining an intact network. The <span class="hlt">current</span> challenge is to unravel the molecular mechanisms underlying the regulation of the keratin cycle in relation to actin and microtubule networks and in the context of epithelial tissue function. PMID:21893596</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/16441167','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/16441167"><span>Force-velocity relationship of single actin <span class="hlt">filament</span> interacting with immobilised myosin measured by electromagnetic technique.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Holohan, S-J P; Marston, S B</p> <p>2005-06-01</p> <p>The effect of applying an external load to actin <span class="hlt">filaments</span> moving in the in vitro motility assay is studied. Bead-tailed actin <span class="hlt">filaments</span> were made by polymerising actin onto 2.8 microm diameter Dynabeads conjugated with gelsolin-G actin. These were introduced into a motility cell coated with 100 microg/ml rabbit fast skeletal myosin in the presence of ATP and 0.5% methylcellulose. The motility cell was inserted between the pole-pieces of an electromagnet and the fluorescent beads and <span class="hlt">filaments</span> were observed. The force-<span class="hlt">current</span> relationship of the electromagnet was determined from the velocity of free beads in viscous solution and Stokes' equation. The magnet produced up to 6 pN force on the Dynabeads at 1 A. Many bead-tailed actin <span class="hlt">filaments</span> stuck to the surface, but the beads that did move moved at the same speed as unloaded f-actin in the same cell. Bead-tailed <span class="hlt">filaments</span> slowed down under an increasing magnetic load, eventually stalled and then slid backward under increasing load before detaching from the surface. Single-<span class="hlt">filament</span> force-velocity curves were constructed and a stalling force of about 0.6 pN/mm of actin <span class="hlt">filament</span> estimated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMSH53A4197W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMSH53A4197W"><span>A Comparison Study of an Active Region Eruptive <span class="hlt">Filament</span> and a Neighboring Non-Eruptive <span class="hlt">Filament</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wu, S. T.; Jiang, C.; Feng, X. S.; Hu, Q.</p> <p>2014-12-01</p> <p>We perform a comparison study of an eruptive <span class="hlt">filament</span> in the core region of AR 11283 and a nearby non-eruptive <span class="hlt">filament</span>. The coronal magnetic field supporting these two <span class="hlt">filaments</span> is extrapolated using our data-driven CESE-MHD-NLFFF code (Jiang et al. 2013, Jiang etal. 2014), which presents two magnetic flux ropes (FRs) in the same extrapolation box. The eruptive FR contains a bald-patch separatrix surface (BPSS) spatially co-aligned very well with a pre-eruption EUV sigmoid, which is consistent with the BPSS model for the coronal sigmoids. The numerically reproduced magnetic dips of the FRs match observations of the <span class="hlt">filaments</span> strikingly well, which supports strongly the FR-dip model for <span class="hlt">filaments</span>. The FR that supports the AR eruptive <span class="hlt">filament</span> is much smaller (with a length of 3 Mm) compared with the large-scale FR holding the quiescent <span class="hlt">filament</span> (with a length of 30 Mm). But the AR eruptive FR contains most of the magnetic free energy in the extrapolation box and holds a much higher magnetic energy density than the quiescent FR, because it resides along the main polarity inversion line (PIL) around sunspots with strong magnetic shear. Both the FRs are weakly twisted and cannot trigger kink instability. The AR eruptive FR is unstable because its axis reaches above a critical height for torus instability (TI), at which the overlying closed arcades can no longer confine the FR stably. To the contrary, the quiescent FR is firmly held down by its overlying field, as its axis apex is far below the TI threshold height. (This work is partially supported by NSF AGS-1153323 and 1062050)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22663352-high-resolution-observations-sympathetic-filament-eruptions-nvst','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22663352-high-resolution-observations-sympathetic-filament-eruptions-nvst"><span>High-resolution Observations of Sympathetic <span class="hlt">Filament</span> Eruptions by NVST</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>Li, Shangwei; Su, Yingna; Zhou, Tuanhui</p> <p></p> <p>We investigate two sympathetic <span class="hlt">filament</span> eruptions observed by the New Vacuum Solar Telescope on 2015 October 15. The full picture of the eruptions is obtained from the corresponding Solar Dynamics Observatory ( SDO )/Atmospheric Imaging Assembly (AIA) observations. The two <span class="hlt">filaments</span> start from active region NOAA 12434 in the north and end in one large quiescent <span class="hlt">filament</span> channel in the south. The left <span class="hlt">filament</span> erupts first, followed by the right <span class="hlt">filament</span> eruption about 10 minutes later. Clear twist structure and rotating motion are observed in both <span class="hlt">filaments</span> during the eruption. Both eruptions failed, since the <span class="hlt">filaments</span> first rise up, thenmore » flow toward the south and merge into the southern large quiescent <span class="hlt">filament</span>. We also observe repeated activations of mini <span class="hlt">filaments</span> below the right <span class="hlt">filament</span> after its eruption. Using magnetic field models constructed based on SDO /HMI magnetograms via the flux rope insertion method, we find that the left <span class="hlt">filament</span> eruption is likely to be triggered by kink instability, while the weakening of overlying magnetic fields due to magnetic reconnection at an X-point between the two <span class="hlt">filament</span> systems might play an important role in the onset of the right <span class="hlt">filament</span> eruption.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016APS..DPPJO7010L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016APS..DPPJO7010L"><span>Electron plasma wave <span class="hlt">filamentation</span> in the kinetic regime</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lushnikov, Pavel; Rose, Harvey; Silantyev, Denis</p> <p>2016-10-01</p> <p>We consider nonlinear electron plasma wave (EPW) dynamics in the kinetic wavenumber regime, 0.25 < kλD < 0.45 , which is typical for <span class="hlt">current</span> high temperature laser-plasma interaction experiments, where k is the EPW wavenumber and λD is the electron Debye length. In this kinetic regime, EPW frequency reduction due to electron trapping may dominate the ponderomotive frequency shift. Previous 3D PIC simulations showed that the trapped electron EPW <span class="hlt">filamentation</span> instability can saturate stimulated Raman backscatter by reducing the EPWs coherence but multidimensional Vlasov simulations [1] are needed to address that saturation in details. We performed nonlinear, non-equilibrium 2D Vlasov simulations to study the EPW <span class="hlt">filamentation</span>. The initial conditions are created either by external forcing or by constructing the appropriate 1D travelling Bernstein-Greene-Kruskal (BGK) mode. Transverse perturbations of any of these initial conditions grow with time eventually producing strongly nonlinear <span class="hlt">filamentation</span> followed by plasma turbulence. We compared these simulations with the theoretical results on growth rates of the transverse instability BGK mode showing the satisfactory agreement. Supported by the New Mexico Consortium and NSF DMS-1412140.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25978269','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25978269"><span>Generalized minimal principle for rotor <span class="hlt">filaments</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Dierckx, Hans; Wellner, Marcel; Bernus, Olivier; Verschelde, Henri</p> <p>2015-05-01</p> <p>To a reaction-diffusion medium with an inhomogeneous anisotropic diffusion tensor D, we add a fourth spatial dimension such that the determinant of the diffusion tensor is constant in four dimensions. We propose a generalized minimal principle for rotor <span class="hlt">filaments</span>, stating that the scroll wave <span class="hlt">filament</span> strives to minimize its surface area in the higher-dimensional space. As a consequence, stationary scroll wave <span class="hlt">filaments</span> in the original 3D medium are geodesic curves with respect to the metric tensor G=det(D)D(-1). The theory is confirmed by numerical simulations for positive and negative <span class="hlt">filament</span> tension and a model with a non-stationary spiral core. We conclude that <span class="hlt">filaments</span> in cardiac tissue with positive tension preferentially reside or anchor in regions where cardiac cells are less interconnected, such as portions of the cardiac wall with a large number of cleavage planes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4763786','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4763786"><span>Quantitative nanoscale imaging of orientational order in biological <span class="hlt">filaments</span> by polarized superresolution microscopy</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Valades Cruz, Cesar Augusto; Shaban, Haitham Ahmed; Kress, Alla; Bertaux, Nicolas; Monneret, Serge; Mavrakis, Manos; Savatier, Julien; Brasselet, Sophie</p> <p>2016-01-01</p> <p>Essential cellular functions as diverse as genome maintenance and tissue morphogenesis rely on the dynamic organization of <span class="hlt">filamentous</span> assemblies. For example, the precise structural organization of DNA <span class="hlt">filaments</span> has profound consequences on all DNA-mediated processes including gene expression, whereas control over the precise spatial arrangement of cytoskeletal protein <span class="hlt">filaments</span> is key for mechanical force generation driving animal tissue morphogenesis. Polarized fluorescence is <span class="hlt">currently</span> used to extract structural organization of fluorescently labeled biological <span class="hlt">filaments</span> by determining the orientation of fluorescent labels, however with a strong drawback: polarized fluorescence imaging is indeed spatially limited by optical diffraction, and is thus unable to discriminate between the intrinsic orientational mobility of the fluorophore labels and the real structural disorder of the labeled biomolecules. Here, we demonstrate that quantitative single-molecule polarized detection in biological <span class="hlt">filament</span> assemblies allows not only to correct for the rotational flexibility of the label but also to image orientational order of <span class="hlt">filaments</span> at the nanoscale using superresolution capabilities. The method is based on polarized direct stochastic optical reconstruction microscopy, using dedicated optical scheme and image analysis to determine both molecular localization and orientation with high precision. We apply this method to double-stranded DNA in vitro and microtubules and actin stress fibers in whole cells. PMID:26831082</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010A%26A...521A..72S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010A%26A...521A..72S"><span>Striation and convection in penumbral <span class="hlt">filaments</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Spruit, H. C.; Scharmer, G. B.; Löfdahl, M. G.</p> <p>2010-10-01</p> <p>Observations with the 1-m Swedish Solar Telescope of the flows seen in penumbral <span class="hlt">filaments</span> are presented. Time sequences of bright <span class="hlt">filaments</span> show overturning motions strikingly similar to those seen along the walls of small isolated structures in the active regions. The <span class="hlt">filaments</span> show outward propagating striations with inclination angles suggesting that they are aligned with the local magnetic field. We interpret it as the equivalent of the striations seen in the walls of small isolated magnetic structures. Their origin is then a corrugation of the boundary between an overturning convective flow inside the <span class="hlt">filament</span> and the magnetic field wrapping around it. The outward propagation is a combination of a pattern motion due to the downflow observed along the sides of bright <span class="hlt">filaments</span>, and the Evershed flow. The observed short wavelength of the striation argues against the existence of a dynamically significant horizontal field inside the bright <span class="hlt">filaments</span>. Its intensity contrast is explained by the same physical effect that causes the dark cores of <span class="hlt">filaments</span>, light bridges and “canals”. In this way striation represents an important clue to the physics of penumbral structure and its relation with other magnetic structures on the solar surface. We put this in perspective with results from the recent 3-D radiative hydrodynamic simulations. 4 movies are only available in electronic form at http://www.aanda.org</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19950047162&hterms=current+situation&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dcurrent%2Bsituation','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19950047162&hterms=current+situation&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dcurrent%2Bsituation"><span>A study of weak anisotropy in electron pressure in the tail <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>Lee, D.-Y.; Voigt, G.-H.</p> <p>1995-01-01</p> <p>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 <span class="hlt">current</span> 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 <span class="hlt">current</span> density is notable only near the center of the tail <span class="hlt">current</span> <span class="hlt">sheet</span> (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.</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> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013ApJ...775L..32A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013ApJ...775L..32A"><span>Anti-parallel EUV Flows Observed along Active Region <span class="hlt">Filament</span> Threads with Hi-C</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Alexander, Caroline E.; Walsh, Robert W.; Régnier, Stéphane; Cirtain, Jonathan; Winebarger, Amy R.; Golub, Leon; Kobayashi, Ken; Platt, Simon; Mitchell, Nick; Korreck, Kelly; DePontieu, Bart; DeForest, Craig; Weber, Mark; Title, Alan; Kuzin, Sergey</p> <p>2013-09-01</p> <p>Plasma flows within prominences/<span class="hlt">filaments</span> have been observed for many years and hold valuable clues concerning the mass and energy balance within these structures. Previous observations of these flows primarily come from Hα and cool extreme-ultraviolet (EUV) lines (e.g., 304 Å) where estimates of the size of the prominence threads has been limited by the resolution of the available instrumentation. Evidence of "counter-steaming" flows has previously been inferred from these cool plasma observations, but now, for the first time, these flows have been directly imaged along fundamental <span class="hlt">filament</span> threads within the million degree corona (at 193 Å). In this work, we present observations of an AR <span class="hlt">filament</span> observed with the High-resolution Coronal Imager (Hi-C) that exhibits anti-parallel flows along adjacent <span class="hlt">filament</span> threads. Complementary data from the Solar Dynamics Observatory (SDO)/Atmospheric Imaging Assembly (AIA) and Helioseismic and Magnetic Imager are presented. The ultra-high spatial and temporal resolution of Hi-C allow the anti-parallel flow velocities to be measured (70-80 km s-1) and gives an indication of the resolvable thickness of the individual strands (0.''8 ± 0.''1). The temperature of the plasma flows was estimated to be log T (K) = 5.45 ± 0.10 using Emission Measure loci analysis. We find that SDO/AIA cannot clearly observe these anti-parallel flows or measure their velocity or thread width due to its larger pixel size. We suggest that anti-parallel/counter-streaming flows are likely commonplace within all <span class="hlt">filaments</span> and are <span class="hlt">currently</span> not observed in EUV due to <span class="hlt">current</span> instrument spatial resolution.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2000PhyD..146..221S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2000PhyD..146..221S"><span>The Stokesian hydrodynamics of flexing, stretching <span class="hlt">filaments</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Shelley, Michael J.; Ueda, Tetsuji</p> <p>2000-11-01</p> <p>A central element of many fundamental problems in physics and biology lies in the interaction of a viscous fluid with slender, elastic <span class="hlt">filaments</span>. Examples arise in the dynamics of biological fibers, the motility of microscopic organisms, and in phase transitions of liquid crystals. When considering the dynamics on the scale of a single <span class="hlt">filament</span>, the surrounding fluid can often be assumed to be inertialess and hence governed by the Stokes’ equations. A typical simplification then is to assume a local relation, along the <span class="hlt">filament</span>, between the force per unit length exerted by the <span class="hlt">filament</span> upon the fluid and the velocity of the <span class="hlt">filament</span>. While this assumption can be justified through slender-body theory as the leading-order effect, this approximation is only logarithmically separated (in aspect ratio) from the next-order contribution capturing the first effects of non-local interactions mediated by the surrounding fluid; non-local interactions become increasingly important as a <span class="hlt">filament</span> comes within proximity to itself, or another <span class="hlt">filament</span>. Motivated by a pattern forming system in isotropic to smectic-A phase transitions, we consider the non-local Stokesian dynamics of a growing elastica immersed in a fluid. The non-local interactions of the <span class="hlt">filament</span> with itself are included using a modification of the slender-body theory of Keller and Rubinow. This modification is asymptotically equivalent, and removes an instability of their formulation at small, unphysical length-scales. Within this system, the <span class="hlt">filament</span> lives on a marginal stability boundary, driven by a continual process of growth and buckling. Repeated bucklings result in <span class="hlt">filament</span> flex, which, coupled to the non-local interactions and mediated by elastic response, leads to the development of space-filling patterns. We develop numerical methods to solve this system accurately and efficiently, even in the presence of temporal stiffness and the close self-approach of the <span class="hlt">filament</span>. While we have ignored many of the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=545539','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=545539"><span>Mini-thin <span class="hlt">filaments</span> regulated by troponin–tropomyosin</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Gong, Huiyu; Hatch, Victoria; Ali, Laith; Lehman, William; Craig, Roger; Tobacman, Larry S.</p> <p>2005-01-01</p> <p>Striated muscle thin <span class="hlt">filaments</span> contain hundreds of actin monomers and scores of troponins and tropomyosins. To study the cooperative mechanism of thin <span class="hlt">filaments</span>, “mini-thin filaments” were generated by isolating particles nearly matching the minimal structural repeat of thin <span class="hlt">filaments</span>: a double helix of actin subunits with each strand approximately seven actins long and spanned by a troponin–tropomyosin complex. One end of the particles was capped by a gelsolin (segment 1–3)–TnT fusion protein (substituting for normal TnT), and the other end was capped by tropomodulin. EM showed that the particles were 46 ± 9 nm long, with a knob-like mass attributable to gelsolin at one end. Average actin, tropomyosin, and gelsolin–troponin composition indicated one troponin–tropomyosin attached to each strand of the two-stranded actin <span class="hlt">filament</span>. The minifilaments thus nearly represent single regulatory units of thin <span class="hlt">filaments</span>. The myosin S1 MgATPase rate stimulated by the minifilaments was Ca2+-sensitive, indicating that single regulatory length particles are sufficient for regulation. Ca2+ bound cooperatively to cardiac TnC in conventional thin <span class="hlt">filaments</span> but noncooperatively to cardiac TnC in minifilaments in the absence of myosin. This suggests that thin <span class="hlt">filament</span> Ca2+-binding cooperativity reflects indirect troponin–troponin interactions along the long axis of conventional <span class="hlt">filaments</span>, which do not occur in minifilaments. Despite noncooperative Ca2+ binding to minifilaments in the absence of myosin, Ca2+ cooperatively activated the myosin S1-particle ATPase rate. Two-stranded single regulatory units therefore may be sufficient for myosin-mediated Ca2+-binding cooperativity. Functional mini-thin <span class="hlt">filaments</span> are well suited for biochemical and structural analysis of thin-<span class="hlt">filament</span> regulation. PMID:15644437</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JChPh.146b4901M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JChPh.146b4901M"><span>Colloidal transport by active <span class="hlt">filaments</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Manna, Raj Kumar; Kumar, P. B. Sunil; Adhikari, R.</p> <p>2017-01-01</p> <p>Enhanced colloidal transport beyond the limit imposed by diffusion is usually achieved through external fields. Here, we demonstrate the ballistic transport of a colloidal sphere using internal sources of energy provided by an attached active <span class="hlt">filament</span>. The latter is modeled as a chain of chemo-mechanically active beads connected by potentials that enforce semi-flexibility and self-avoidance. The fluid flow produced by the active beads and the forces they mediate are explicitly taken into account in the overdamped equations of motion describing the colloid-<span class="hlt">filament</span> assembly. The speed and efficiency of transport depend on the dynamical conformational states of the <span class="hlt">filament</span>. We characterize these states using <span class="hlt">filament</span> writhe as an order parameter and identify ones yielding maxima in speed and efficiency of transport. The transport mechanism reported here has a remarkable resemblance to the flagellar propulsion of microorganisms which suggests its utility in biomimetic systems.</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('https://ntrs.nasa.gov/search.jsp?R=19890000449&hterms=fog+collection&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dfog%2Bcollection','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19890000449&hterms=fog+collection&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dfog%2Bcollection"><span>Convergent-<span class="hlt">Filament</span> Nonmechanical Pump</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Collins, Earl R., Jr.</p> <p>1989-01-01</p> <p>Simple device induces small flow of liquid without help of moving parts, in presence or absence of gravity. Drops of liquid move on <span class="hlt">filaments</span> from wide end of cone to narrow end. Gradually blend with drops on adjacent <span class="hlt">filaments</span> to form large drops with menisci. Important use expected to be returning liquid condensate in heat pipes, and collection of samples from clouds or fog.</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> </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('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://hdl.handle.net/2060/20120014333','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20120014333"><span>Ultraminiature broadband light source with spiral shaped <span class="hlt">filament</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>McConaghy, Charles F. (Inventor); Olsen, Barry L. (Inventor); Tuma, Margaret L. (Inventor); Collura, Joseph S. (Inventor); Pocha, Michael D. (Inventor); Helvajian, Henry (Inventor); Meyer, Glenn A. (Inventor); Hansen, William W (Inventor)</p> <p>2012-01-01</p> <p>An ultraminiature light source using a double-spiral shaped tungsten <span class="hlt">filament</span> includes end contact portions which are separated to allow for radial and length-wise unwinding of the spiral. The double-spiral <span class="hlt">filament</span> is spaced relatively far apart at the end portions thereof so that contact between portions of the <span class="hlt">filament</span> upon expansion is avoided. The light source is made by fabricating a double-spiral ultraminiature tungsten <span class="hlt">filament</span> from tungsten foil and housing the <span class="hlt">filament</span> in a ceramic package having a reflective bottom and a well wherein the <span class="hlt">filament</span> is suspended. A vacuum furnace brazing process attaches the <span class="hlt">filament</span> to contacts of the ceramic package. Finally, a cover with a transparent window is attached onto the top of the ceramic package by solder reflow in a second vacuum furnace process to form a complete hermetically sealed package.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20160009176','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20160009176"><span>Additive Manufacturing of Multifunctional Components Using High Density Carbon Nanotube Yarn <span class="hlt">Filaments</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Gardner, John M.; Sauti, Godfrey; Kim, Jae-Woo; Cano, Roberto J.; Wincheski, Russell A.; Stelter, Christopher J.; Grimsley, Brian W.; Working, Dennis C.; Siochi, Emilie J.</p> <p>2016-01-01</p> <p>Additive manufacturing allows for design freedom and part complexity not <span class="hlt">currently</span> attainable using traditional manufacturing technologies. Fused <span class="hlt">Filament</span> Fabrication (FFF), for example, can yield novel component geometries and functionalities because the method provides a high level of control over material placement and processing conditions. This is achievable by extrusion of a preprocessed <span class="hlt">filament</span> feedstock material along a predetermined path. However if fabrication of a multifunctional part relies only on conventional <span class="hlt">filament</span> materials, it will require a different material for each unique functionality printed into the part. Carbon nanotubes (CNTs) are an attractive material for many applications due to their high specific strength as well as good electrical and thermal conductivity. The presence of this set of properties in a single material presents an opportunity to use one material to achieve multifunctionality in an additively manufactured part. This paper describes a recently developed method for processing continuous CNT yarn <span class="hlt">filaments</span> into three-dimensional articles, and summarizes the mechanical, electrical, and sensing performance of the components fabricated in this way.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1395253','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/1395253"><span>Graphene-based <span class="hlt">filament</span> material for thermal ionization</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>Hewitt, J.; Shick, C.; Siegfried, M.</p> <p></p> <p>The use of graphene oxide materials for thermal ionization mass spectrometry analysis of plutonium and uranium has been investigated. <span class="hlt">Filament</span> made from graphene oxide slurries have been 3-D printed. A method for attaching these <span class="hlt">filaments</span> to commercial thermal ionization post assemblies has been devised. Resistive heating of the graphene based <span class="hlt">filaments</span> under high vacuum showed stable operation in excess of 4 hours. Plutonium ion production has been observed in an initial set of <span class="hlt">filaments</span> spiked with the Pu 128 Certified Reference Material.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19870011473','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19870011473"><span><span class="hlt">Filament</span> eruption connected to protospheric activity</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Simon, G.; Gesztelyi, L.; Schmieder, B.; Mein, N</p> <p>1986-01-01</p> <p>Two cases of activation of <span class="hlt">filaments</span> that occured in regions of intense magnetic activity was studied. The simultaneous observations from Debrecen Observatory (white light and H alpha filtergram), and from Meudon Observatory (magnetogram, MSDP dopplergram and intensity maps in H alpha) gave a complementary set of data from which can be produced evidence of the influence of the photospheric magnetic field on the destabilization process of the <span class="hlt">filaments</span>. On June 22, 1980, the eruption of the <span class="hlt">filament</span> is associated with the motion of pores, which are manifestations of emerging flux knots. On September 3, 1980, the twisting motions in the <span class="hlt">filament</span> are associated to the birth of a pore in its neighborhood. These observations are discussed.</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://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 tail <span class="hlt">current</span> <span class="hlt">sheet</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013APS..DFDA33004K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013APS..DFDA33004K"><span>Dynamics of contracting surfactant-covered <span class="hlt">filaments</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kamat, Pritish; Thete, Sumeet; Xu, Qi; Basaran, Osman</p> <p>2013-11-01</p> <p>When drops are produced from a nozzle, a thin liquid thread connects the primary drop that is about to form to the rest of the liquid in the nozzle. Often, the thread becomes disconnected from both the primary drop and the remnant liquid mass hanging from the nozzle and thereby gives rise to a free <span class="hlt">filament</span>. Due to surface tension, the free <span class="hlt">filament</span> then contracts or recoils. During recoil, the <span class="hlt">filament</span> can either contract into a single satellite droplet or break up into several small satellites. Such satellite droplets are undesirable in applications where they can, for example, cause misting in a manufacturing environment and mar product quality in ink-jet printing. In many applications, the <span class="hlt">filaments</span> are coated with a monolayer of surfactant. In this work, we study the dynamics of contraction of slender <span class="hlt">filaments</span> of a Newtonian fluid that are covered with a monolayer of surfactant when the surrounding fluid is a passive gas. Taking advantage of the fact that the <span class="hlt">filaments</span> are long and slender, we use a 1D-slender-jet approximation of the governing system of equations consisting of the Navier-Stokes system and the convection-diffusion equation for surfactant transport. We solve the 1D system of equations by a finite element based numerical method.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22666281-interaction-two-filament-channels-different-chiralities','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22666281-interaction-two-filament-channels-different-chiralities"><span>INTERACTION OF TWO <span class="hlt">FILAMENT</span> CHANNELS OF DIFFERENT CHIRALITIES</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>Joshi, Navin Chandra; Magara, Tetsuya; Moon, Yong-Jae</p> <p>2016-07-10</p> <p>We present observations of the interactions between the two <span class="hlt">filament</span> channels of different chiralities and associated dynamics that occurred during 2014 April 18–20. While two flux ropes of different helicity with parallel axial magnetic fields can only undergo a bounce interaction when they are brought together, the observations at first glance show that the heated plasma is moving from one <span class="hlt">filament</span> channel to the other. The SDO /AIA 171 Å observations and the potential-field source-surface magnetic field extrapolation reveal the presence of a fan-spine magnetic configuration over the <span class="hlt">filament</span> channels with a null point located above them. Three different eventsmore » of <span class="hlt">filament</span> activations, partial eruptions, and associated <span class="hlt">filament</span> channel interactions have been observed. The activation initiated in one <span class="hlt">filament</span> channel seems to propagate along the neighboring <span class="hlt">filament</span> channel. We believe that the activation and partial eruption of the <span class="hlt">filaments</span> brings the field lines of flux ropes containing them closer to the null point and triggers the magnetic reconnection between them and the fan-spine magnetic configuration. As a result, the hot plasma moves along the outer spine line toward the remote point. Utilizing the present observations, for the first time we have discussed how two different-chirality <span class="hlt">filament</span> channels can interact and show interrelation.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018MNRAS.475.1646F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018MNRAS.475.1646F"><span>Two-step solar <span class="hlt">filament</span> eruptions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Filippov, B.</p> <p>2018-04-01</p> <p>Coronal mass ejections (CMEs) are closely related to eruptive <span class="hlt">filaments</span> and usually are the continuation of the same eruptive process into the upper corona. There are failed <span class="hlt">filament</span> eruptions when a <span class="hlt">filament</span> decelerates and stops at some greater height in the corona. Sometimes the <span class="hlt">filament</span> after several hours starts to rise again and develops into the successful eruption with a CME formation. We propose a simple model for the interpretation of such two-step eruptions in terms of equilibrium of a flux rope in a two-scale ambient magnetic field. The eruption is caused by a slow decrease of the holding magnetic field. The presence of two critical heights for the initiation of the flux-rope vertical instability allows the flux rope to stay after the first jump some time in a metastable equilibrium near the second critical height. If the decrease of the ambient field continues, the next eruption step follows.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014A%26A...564A.104S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014A%26A...564A.104S"><span>Proper horizontal photospheric flows in a <span class="hlt">filament</span> channel</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schmieder, B.; Roudier, T.; Mein, N.; Mein, P.; Malherbe, J. M.; Chandra, R.</p> <p>2014-04-01</p> <p>Context. An extended <span class="hlt">filament</span> in the central part of the active region NOAA 11106 crossed the central meridian on Sept. 17, 2010 in the southern hemisphere. It has been observed in Hα with the THEMIS telescope in the Canary Islands and in 304 Å with the EUV imager (AIA) onboard the Solar Dynamic Observatory (SDO). Counterstreaming along the Hα threads and bright moving blobs (jets) along the 304 Å <span class="hlt">filament</span> channel were observed during 10 h before the <span class="hlt">filament</span> erupted at 17:03 UT. Aims: The aim of the paper is to understand the coupling between magnetic field and convection in <span class="hlt">filament</span> channels and relate the horizontal photospheric motions to the activity of the <span class="hlt">filament</span>. Methods: An analysis of the proper photospheric motions using SDO/HMI continuum images with the new version of the coherent structure tracking (CST) algorithm developed to track granules, as well as the large scale photospheric flows, was performed for three hours. Using corks, we derived the passive scalar points and produced a map of the cork distribution in the <span class="hlt">filament</span> channel. Averaging the velocity vectors in the southern hemisphere in each latitude in steps of 3.5 arcsec, we defined a profile of the differential rotation. Results: Supergranules are clearly identified in the <span class="hlt">filament</span> channel. Diverging flows inside the supergranules are similar in and out of the <span class="hlt">filament</span> channel. Converging flows corresponding to the accumulation of corks are identified well around the Hα <span class="hlt">filament</span> feet and at the edges of the EUV <span class="hlt">filament</span> channel. At these convergence points, the horizontal photospheric velocity may reach 1 km s-1, but with a mean velocity of 0.35 km s-1. In some locations, horizontal flows crossing the channel are detected, indicating eventually large scale vorticity. Conclusions: The coupling between convection and magnetic field in the photosphere is relatively strong. The <span class="hlt">filament</span> experienced the convection motions through its anchorage points with the photosphere, which are</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19940033528&hterms=kaufmann&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAuthor-Name%26N%3D0%26No%3D40%26Ntt%3Dkaufmann','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19940033528&hterms=kaufmann&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAuthor-Name%26N%3D0%26No%3D40%26Ntt%3Dkaufmann"><span>Cross-tail <span class="hlt">current</span> - Resonant orbits</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.; Lu, Chen</p> <p>1993-01-01</p> <p>A technique to generate self-consistent 1D <span class="hlt">current</span> <span class="hlt">sheets</span> is described. Groups of monoenergetic protons were followed in a modified Harris magnetic field. This sample <span class="hlt">current</span> <span class="hlt">sheet</span> is characterized by resonant quasi-adiabatic orbits. The magnetic moment of a quasi-adiabatic ion which is injected from outside a <span class="hlt">current</span> <span class="hlt">sheet</span> 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 <span class="hlt">sheet</span> in which the charged particles carry the <span class="hlt">currents</span> 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 <span class="hlt">current</span>, but cannot adequately describe any region of the magnetotail in which the principal <span class="hlt">current</span> <span class="hlt">sheet</span> is separated from the plasma <span class="hlt">sheet</span> boundary layer by a nearly isotropic outer position of the central plasma <span class="hlt">sheet</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22661257-plasma-brightenings-failed-solar-filament-eruption','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22661257-plasma-brightenings-failed-solar-filament-eruption"><span>Plasma Brightenings in a Failed Solar <span class="hlt">Filament</span> Eruption</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>Li, Y.; Ding, M. D., E-mail: yingli@nju.edu.cn</p> <p></p> <p>Failed <span class="hlt">filament</span> eruptions are solar eruptions that are not associated with coronal mass ejections. In a failed <span class="hlt">filament</span> eruption, the <span class="hlt">filament</span> materials usually show some ascending and falling motions as well as generating bright EUV emissions. Here we report a failed <span class="hlt">filament</span> eruption (SOL2016-07-22) that occurred in a quiet-Sun region observed by the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory . In this event, the <span class="hlt">filament</span> spreads out but gets confined by the surrounding magnetic field. When interacting with the ambient magnetic field, the <span class="hlt">filament</span> material brightens up and flows along the magnetic field lines through the coronamore » to the chromosphere. We find that some materials slide down along the lifting magnetic structure containing the <span class="hlt">filament</span> and impact the chromosphere, and through kinetic energy dissipation, cause two ribbon-like brightenings in a wide temperature range. There is evidence suggesting that magnetic reconnection occurs between the <span class="hlt">filament</span> magnetic structure and the surrounding magnetic fields where <span class="hlt">filament</span> plasma is heated to coronal temperatures. In addition, thread-like brightenings show up on top of the erupting magnetic fields at low temperatures, which might be produced by an energy imbalance from a fast drop of radiative cooling due to plasma rarefaction. Thus, this single event of a failed <span class="hlt">filament</span> eruption shows the existence of a variety of plasma brightenings that may be caused by completely different heating mechanisms.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017MS%26E..275a2033L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017MS%26E..275a2033L"><span>Fabrication of PLA <span class="hlt">Filaments</span> and its Printable Performance</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Liu, Wenjie; Zhou, Jianping; Ma, Yuming; Wang, Jie; Xu, Jie</p> <p>2017-12-01</p> <p>Fused deposition modeling (FDM) is a typical 3D printing technology and preparation of qualified <span class="hlt">filaments</span> is the basis. In order to prepare polylactic acid (PLA) <span class="hlt">filaments</span> suitable for personalized FDM 3D printing, this article investigated the effect of factors such as extrusion temperature and screw speed on the diameter, surface roughness and ultimate tensile stress of the obtained PLA <span class="hlt">filaments</span>. The optimal process parameters for fabrication of qualified <span class="hlt">filaments</span> were determined. Further, the printable performance of the obtained PLA <span class="hlt">filaments</span> for 3D objects was preliminarily explored.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017APS..DPPPO8010Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017APS..DPPPO8010Y"><span>Development of the striation and <span class="hlt">filament</span> form of the electrothermal instability</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yu, Edmund; Awe, T. J.; Yelton, W. G.; McKenzie, B. B.; Peterson, K. J.; Bauer, B. S.; Hutchinson, T. M.; Fuelling, S.; Yates, K. C.; Shipley, G.</p> <p>2017-10-01</p> <p>Magnetically imploded liners have broad application to ICF, dynamic material property studies, and flux compression. An important consideration in liner performance is the electrothermal instability (ETI), an Ohmic heating instability that manifests in 2 ways: assuming vertical <span class="hlt">current</span> flow, ETI forms hot, horizontal bands (striations) in metals, and vertical <span class="hlt">filaments</span> in plasmas. Striations are especially relevant in that they can develop into density perturbations, which then couple to the dangerous magneto Rayleigh-Taylor (MRT) instability during liner acceleration. Recent visible emission images of Ohmically heated rods show evidence of both the striation and <span class="hlt">filament</span> form of ETI, suggesting several questions: (1) can simulation qualitatively reproduce the data? (2) If so, what seeds the striation ETI, and how does it transition to <span class="hlt">filaments</span>? (3) Does the striation develop into a strong density perturbation, important for MRT? In this work, we use analytic theory and 3D MHD simulation to study how isolated resistive inclusions, embedded in a perfectly smooth rod and communicating through <span class="hlt">current</span> redistribution, can be used to address the above questions. Sandia National Laboratories is a multimission laboratory managed and operated by National Technology and Engineering Solutions of Sandia LLC, a wholly owned subsidiary of Honeywell International Inc. for the U.S. DOE NNSA under contract DE-NA0003525.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22486117-terahertz-waves-radiated-from-two-noncollinear-femtosecond-plasma-filaments','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22486117-terahertz-waves-radiated-from-two-noncollinear-femtosecond-plasma-filaments"><span>Terahertz waves radiated from two noncollinear femtosecond plasma <span class="hlt">filaments</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>Du, Hai-Wei; Hoshina, Hiromichi; Otani, Chiko, E-mail: otani@riken.jp</p> <p>2015-11-23</p> <p>Terahertz (THz) waves radiated from two noncollinear femtosecond plasma <span class="hlt">filaments</span> with a crossing angle of 25° are investigated. The irradiated THz waves from the crossing <span class="hlt">filaments</span> show a small THz pulse after the main THz pulse, which was not observed in those from single-<span class="hlt">filament</span> scheme. Since the position of the small THz pulse changes with the time-delay of two <span class="hlt">filaments</span>, this phenomenon can be explained by a model in which the small THz pulse is from the second <span class="hlt">filament</span>. The denser plasma in the overlap region of the <span class="hlt">filaments</span> changes the movement of space charges in the plasma, thereby changingmore » the angular distribution of THz radiation. As a result, this schematic induces some THz wave from the second <span class="hlt">filament</span> to propagate along the path of the THz wave from the first <span class="hlt">filament</span>. Thus, this schematic alters the direction of the THz radiation from the <span class="hlt">filamentation</span>, which can be used in THz wave remote sensing.« less</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> </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('https://www.osti.gov/biblio/22224073-anti-parallel-euv-flows-observed-along-active-region-filament-threads-hi','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22224073-anti-parallel-euv-flows-observed-along-active-region-filament-threads-hi"><span>ANTI-PARALLEL EUV FLOWS OBSERVED ALONG ACTIVE REGION <span class="hlt">FILAMENT</span> THREADS WITH HI-C</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>Alexander, Caroline E.; Walsh, Robert W.; Régnier, Stéphane</p> <p></p> <p>Plasma flows within prominences/<span class="hlt">filaments</span> have been observed for many years and hold valuable clues concerning the mass and energy balance within these structures. Previous observations of these flows primarily come from Hα and cool extreme-ultraviolet (EUV) lines (e.g., 304 Å) where estimates of the size of the prominence threads has been limited by the resolution of the available instrumentation. Evidence of 'counter-steaming' flows has previously been inferred from these cool plasma observations, but now, for the first time, these flows have been directly imaged along fundamental <span class="hlt">filament</span> threads within the million degree corona (at 193 Å). In this work, wemore » present observations of an AR <span class="hlt">filament</span> observed with the High-resolution Coronal Imager (Hi-C) that exhibits anti-parallel flows along adjacent <span class="hlt">filament</span> threads. Complementary data from the Solar Dynamics Observatory (SDO)/Atmospheric Imaging Assembly (AIA) and Helioseismic and Magnetic Imager are presented. The ultra-high spatial and temporal resolution of Hi-C allow the anti-parallel flow velocities to be measured (70-80 km s{sup –1}) and gives an indication of the resolvable thickness of the individual strands (0.''8 ± 0.''1). The temperature of the plasma flows was estimated to be log T (K) = 5.45 ± 0.10 using Emission Measure loci analysis. We find that SDO/AIA cannot clearly observe these anti-parallel flows or measure their velocity or thread width due to its larger pixel size. We suggest that anti-parallel/counter-streaming flows are likely commonplace within all <span class="hlt">filaments</span> and are <span class="hlt">currently</span> not observed in EUV due to <span class="hlt">current</span> instrument spatial resolution.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/869885','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/869885"><span>Aerogel-supported <span class="hlt">filament</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Wuest, Craig R.; Tillotson, Thomas M.; Johnson, III, Coleman V.</p> <p>1995-01-01</p> <p>The present invention is a thin <span class="hlt">filament</span> embedded in a low density aerogel for use in radiation detection instruments and incandescent lamps. The aerogel provides a supportive matrix that is thermally and electrically nonconductive, mechanically strong, highly porous, gas-permeable, and transparent to ionizing radiation over short distances. A low density, open-cell aerogel is cast around a fine <span class="hlt">filament</span> or wire, which allows the wire to be positioned with little or no tension and keeps the wire in place in the event of breakage. The aerogel support reduces the stresses on the wire caused by vibrational, gravitational, electrical, and mechanical forces.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19660000046','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19660000046"><span>Lamp automatically switches to new <span class="hlt">filament</span> on burnout</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Ingle, W. B.</p> <p>1966-01-01</p> <p>Lamp with primary and secondary <span class="hlt">filaments</span> has a means for automatic switching to the secondary <span class="hlt">filament</span> at primary <span class="hlt">filament</span> burnout. Lamp failures and resultant expenses during oscillograph printing are appreciably reduced.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016RAA....16...18J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016RAA....16...18J"><span>A comparison study of a solar active-region eruptive <span class="hlt">filament</span> and a neighboring non-eruptive <span class="hlt">filament</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jiang, Chao-Wei; Wu, Shi-Tsan; Feng, Xue-Shang; Hu, Qiang</p> <p>2016-01-01</p> <p>Solar active region (AR) 11283 is a very magnetically complex region and it has produced many eruptions. However, there exists a non-eruptive <span class="hlt">filament</span> in the plage region just next to an eruptive one in the AR, which gives us an opportunity to perform a comparison analysis of these two <span class="hlt">filaments</span>. The coronal magnetic field extrapolated using our CESE-MHD-NLFFF code reveals that two magnetic flux ropes (MFRs) exist in the same extrapolation box supporting these two <span class="hlt">filaments</span>, respectively. Analysis of the magnetic field shows that the eruptive MFR contains a bald-patch separatrix surface (BPSS) cospatial very well with a pre-eruptive EUV sigmoid, which is consistent with the BPSS model for coronal sigmoids. The magnetic dips of the non-eruptive MFRs match Hα observation of the non-eruptive <span class="hlt">filament</span> strikingly well, which strongly supports the MFR-dip model for <span class="hlt">filaments</span>. Compared with the non-eruptive MFR/<span class="hlt">filament</span> (with a length of about 200 Mm), the eruptive MFR/<span class="hlt">filament</span> is much smaller (with a length of about 20 Mm), but it contains most of the magnetic free energy in the extrapolation box and holds a much higher free energy density than the non-eruptive one. Both the MFRs are weakly twisted and cannot trigger kink instability. The AR eruptive MFR is unstable because its axis reaches above a critical height for torus instability, at which the overlying closed arcades can no longer confine the MFR stably. On the contrary, the quiescent MFR is very firmly held by its overlying field, as its axis apex is far below the torus-instability threshold height. Overall, this comparison investigation supports that an MFR can exist prior to eruption and the ideal MHD instability can trigger an MFR eruption.</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('http://adsabs.harvard.edu/abs/2017AGUFMSH13A2467Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSH13A2467Z"><span>The Connection Between Solar Coronal Cavities and Solar <span class="hlt">Filaments</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zawadzki, B.; Karna, N.; Prchlik, J.; Reeves, K.; Kempton, D.; Angryk, R.</p> <p>2017-12-01</p> <p><span class="hlt">Filaments</span> are structures in the solar corona made up of relatively cool, dense, partially ionized plasma. Coronal cavities, circular or elliptical regions of low plasma density, are observed above prominences on the solar limb when viewed in EUV and white light coronal images. Since most <span class="hlt">filament</span>/cavity eruptions lead to a coronal mass ejection (CME), determining the likelihood of an eruption event will improve our ability to predict space weather. We examine SDO/AIA cavity metadata and HEK <span class="hlt">filament</span> metadata to determine which cavities are associated with which <span class="hlt">filaments</span> from 2012 to 2015. Our study involved 140 cavities and 368 <span class="hlt">filaments</span> that appeared poleward of +-30 degrees. We categorized the cavities and <span class="hlt">filaments</span> based on the stability of the structures, defined by whether or not the cavity and <span class="hlt">filament</span> exist long enough to track fully across the solar disk. Using these categories we perform a statistical study on various <span class="hlt">filament</span> qualities within the metadata. Our findings indicate that <span class="hlt">filaments</span> with cavities are observed more often at high latitude in compared to <span class="hlt">filaments</span> without cavities. Moreover, our study indicates that a statistically significant difference exists between the <span class="hlt">filament</span> length and tilt distributions for certain categories. This work supported by the NSF-REU solar physics program at SAO, grant number AGS-1560313, and the NSF-DIBBS project, grant number ACI-1443061.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA216220','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA216220"><span>Modeling the Wake as a Continuous Vortex <span class="hlt">Sheet</span> in a Potential-Flow Solution Using Vortex Panels</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>1989-12-01</p> <p>Continuous Vortex <span class="hlt">Sheet</span> ........ 30 0 Redistributing the Vorticity Over anlIncreasing Area ............... 31 System of Linear Equations inG-Primes...i)* 9 ~=- r(x) L~~3 (29) 4v ji -i13 where dl is a differential length along the <span class="hlt">filament</span> dl = dx 1 ( 30 ) when expressed in the local coordinate frame...which 30 models the wing serves as a pattern for this effort, but modifications must be made since the wake is continually growing and distorting. In</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3504962','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3504962"><span>Photophysiology and albedo-changing potential of the ice algal community on the surface of 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>Yallop, Marian L; Anesio, Alexandre M; Perkins, Rupert G; Cook, Joseph; Telling, Jon; Fagan, Daniel; MacFarlane, James; Stibal, Marek; Barker, Gary; Bellas, Chris; Hodson, Andy; Tranter, Martyn; Wadham, Jemma; Roberts, Nicholas W</p> <p>2012-01-01</p> <p>Darkening of parts of the Greenland ice <span class="hlt">sheet</span> surface during the summer months leads to reduced albedo and increased melting. Here we show that heavily pigmented, actively photosynthesising microalgae and cyanobacteria are present on the bare ice. We demonstrate the widespread abundance of green algae in the Zygnematophyceae on the ice <span class="hlt">sheet</span> surface in Southwest Greenland. Photophysiological measurements (variable chlorophyll fluorescence) indicate that the ice algae likely use screening mechanisms to downregulate photosynthesis when exposed to high intensities of visible and ultraviolet radiation, rather than non-photochemical quenching or cell movement. Using imaging microspectrophotometry, we demonstrate that intact cells and <span class="hlt">filaments</span> absorb light with characteristic spectral profiles across ultraviolet and visible wavelengths, whereas inorganic dust particles typical for these areas display little absorption. Our results indicate that the phototrophic community growing directly on the bare ice, through their photophysiology, most likely have an important role in changing albedo, and subsequently may impact melt rates on the ice <span class="hlt">sheet</span>. PMID:23018772</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23018772','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23018772"><span>Photophysiology and albedo-changing potential of the ice algal community on the surface of 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>Yallop, Marian L; Anesio, Alexandre M; Perkins, Rupert G; Cook, Joseph; Telling, Jon; Fagan, Daniel; MacFarlane, James; Stibal, Marek; Barker, Gary; Bellas, Chris; Hodson, Andy; Tranter, Martyn; Wadham, Jemma; Roberts, Nicholas W</p> <p>2012-12-01</p> <p>Darkening of parts of the Greenland ice <span class="hlt">sheet</span> surface during the summer months leads to reduced albedo and increased melting. Here we show that heavily pigmented, actively photosynthesising microalgae and cyanobacteria are present on the bare ice. We demonstrate the widespread abundance of green algae in the Zygnematophyceae on the ice <span class="hlt">sheet</span> surface in Southwest Greenland. Photophysiological measurements (variable chlorophyll fluorescence) indicate that the ice algae likely use screening mechanisms to downregulate photosynthesis when exposed to high intensities of visible and ultraviolet radiation, rather than non-photochemical quenching or cell movement. Using imaging microspectrophotometry, we demonstrate that intact cells and <span class="hlt">filaments</span> absorb light with characteristic spectral profiles across ultraviolet and visible wavelengths, whereas inorganic dust particles typical for these areas display little absorption. Our results indicate that the phototrophic community growing directly on the bare ice, through their photophysiology, most likely have an important role in changing albedo, and subsequently may impact melt rates on the ice <span class="hlt">sheet</span>.</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('http://adsabs.harvard.edu/abs/2017EGUGA..1911067Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1911067Y"><span>Observations of the Growth of an Active Region <span class="hlt">Filament</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yang, Bo</p> <p>2017-04-01</p> <p>We present observations of the growth of an active region <span class="hlt">filament</span> caused by magnetic interactions among the <span class="hlt">filament</span> and its adjacent superpenumbral <span class="hlt">filament</span> (SF) and dark thread-like structures (T). Multistep reconnections are identified during the whole growing process. Magnetic flux convergence and cancellation occurring at the positive footpoint region of the <span class="hlt">filament</span> is the first step reconnection, which resulted in the <span class="hlt">filament</span> bifurcating into two sets of intertwined threads. One set anchored in situ, while the other set moved toward and interacted with the SF and part of T. This indicates the second step reconnection, which gave rise to the disappearance of the SF and the formation of a long thread-like structure that connects the far ends of the <span class="hlt">filament</span> and T. The long thread-like structure further interacted with the T and then separated into two parts, representing the third step reconnection. Finally, another similar long thread-like structure, which intertwined with the fixed <span class="hlt">filament</span> threads, appeared. Hαobservations show that this twisted structure is a longer sinistral <span class="hlt">filament</span>. Based on the observed photospheric vector magnetograms, we performed a non-linear force-free field extrapolation to reconstruct the magnetic fields above the photosphere and found that the coronal magnetic field lines associated with the <span class="hlt">filament</span> consists of two twisted flux ropes winding around each other. These results suggest that magnetic interactions among <span class="hlt">filaments</span> and their adjacent SFs and T could lead to the growth of the <span class="hlt">filaments</span>, and the <span class="hlt">filament</span> is probably supported in a flux rope.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22667368-observations-growth-active-region-filament','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22667368-observations-growth-active-region-filament"><span>OBSERVATIONS OF THE GROWTH OF AN ACTIVE REGION <span class="hlt">FILAMENT</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>Yang, Bo; Jiang, Yunchun; Yang, Jiayan</p> <p></p> <p>We present observations of the growth of an active region <span class="hlt">filament</span> caused by magnetic interactions among the <span class="hlt">filament</span> and its adjacent superpenumbral <span class="hlt">filament</span> (SF) and dark thread-like structures (T). Multistep reconnections are identified during the whole growing process. Magnetic flux convergence and cancellation occurring at the positive footpoint region of the <span class="hlt">filament</span> is the first step reconnection, which resulted in the <span class="hlt">filament</span> bifurcating into two sets of intertwined threads. One set anchored in situ, while the other set moved toward and interacted with the SF and part of T. This indicates the second step reconnection, which gave rise to themore » disappearance of the SF and the formation of a long thread-like structure that connects the far ends of the <span class="hlt">filament</span> and T. The long thread-like structure further interacted with the T and then separated into two parts, representing the third step reconnection. Finally, another similar long thread-like structure, which intertwined with the fixed <span class="hlt">filament</span> threads, appeared. H {sub α} observations show that this twisted structure is a longer sinistral <span class="hlt">filament</span>. Based on the observed photospheric vector magnetograms, we performed a non-linear force-free field extrapolation to reconstruct the magnetic fields above the photosphere and found that the coronal magnetic field lines associated with the <span class="hlt">filament</span> consists of two twisted flux ropes winding around each other. These results suggest that magnetic interactions among <span class="hlt">filaments</span> and their adjacent SFs and T could lead to the growth of the <span class="hlt">filaments</span>, and the <span class="hlt">filament</span> is probably supported in a flux rope.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016IAUS..308...97N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016IAUS..308...97N"><span>An Origami Approximation to the Cosmic Web</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Neyrinck, Mark C.</p> <p>2016-10-01</p> <p>The powerful Lagrangian view of structure formation was essentially introduced to cosmology by Zel'dovich. In the <span class="hlt">current</span> cosmological paradigm, a dark-matter-<span class="hlt">sheet</span> 3D manifold, inhabiting 6D position-velocity phase space, was flat (with vanishing velocity) at the big bang. Afterward, gravity stretched and bunched the <span class="hlt">sheet</span> together in different places, forming a cosmic web when projected to the position coordinates. Here, I explain some properties of an origami approximation, in which the <span class="hlt">sheet</span> does not stretch or contract (an assumption that is false in general), but is allowed to fold. Even without stretching, the <span class="hlt">sheet</span> can form an idealized cosmic web, with convex polyhedral voids separated by straight walls and <span class="hlt">filaments</span>, joined by convex polyhedral nodes. The nodes form in `polygonal' or `polyhedral' collapse, somewhat like spherical/ellipsoidal collapse, except incorporating simultaneous <span class="hlt">filament</span> and wall formation. The origami approximation allows phase-space geometries of nodes, <span class="hlt">filaments</span>, and walls to be more easily understood, and may aid in understanding spin correlations between nearby galaxies. This contribution explores kinematic origami-approximation models giving velocity fields for the first time.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28096266','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28096266"><span>Desmosomes and Intermediate <span class="hlt">Filaments</span>: Their Consequences for Tissue Mechanics.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hatzfeld, Mechthild; Keil, René; Magin, Thomas M</p> <p>2017-06-01</p> <p>Adherens junctions (AJs) and desmosomes connect the actin and keratin <span class="hlt">filament</span> networks of adjacent cells into a mechanical unit. Whereas AJs function in mechanosensing and in transducing mechanical forces between the plasma membrane and the actomyosin cytoskeleton, desmosomes and intermediate <span class="hlt">filaments</span> (IFs) provide mechanical stability required to maintain tissue architecture and integrity when the tissues are exposed to mechanical stress. Desmosomes are essential for stable intercellular cohesion, whereas keratins determine cell mechanics but are not involved in generating tension. Here, we summarize the <span class="hlt">current</span> knowledge of the role of IFs and desmosomes in tissue mechanics and discuss whether the desmosome-keratin scaffold might be actively involved in mechanosensing and in the conversion of chemical signals into mechanical strength. Copyright © 2017 Cold Spring Harbor Laboratory Press; all rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26497658','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26497658"><span>Brownian microhydrodynamics of active <span class="hlt">filaments</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Laskar, Abhrajit; Adhikari, R</p> <p>2015-12-21</p> <p>Slender bodies capable of spontaneous motion in the absence of external actuation in an otherwise quiescent fluid are common in biological, physical and technological contexts. The interplay between the spontaneous fluid flow, Brownian motion, and the elasticity of the body presents a challenging fluid-structure interaction problem. Here, we model this problem by approximating the slender body as an elastic <span class="hlt">filament</span> that can impose non-equilibrium velocities or stresses at the fluid-structure interface. We derive equations of motion for such an active <span class="hlt">filament</span> by enforcing momentum conservation in the fluid-structure interaction and assuming slow viscous flow in the fluid. The fluid-structure interaction is obtained, to any desired degree of accuracy, through the solution of an integral equation. A simplified form of the equations of motion, which allows for efficient numerical solutions, is obtained by applying the Kirkwood-Riseman superposition approximation to the integral equation. We use this form of equation of motion to study dynamical steady states in free and hinged minimally active <span class="hlt">filaments</span>. Our model provides the foundation to study collective phenomena in momentum-conserving, Brownian, active <span class="hlt">filament</span> suspensions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26561133','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26561133"><span>Remote electrical arc suppression by laser <span class="hlt">filamentation</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Schubert, Elise; Mongin, Denis; Kasparian, Jérôme; Wolf, Jean-Pierre</p> <p>2015-11-02</p> <p>We investigate the interaction of narrow plasma channels formed in the <span class="hlt">filamentation</span> of ultrashort laser pulses, with a DC high voltage. The laser <span class="hlt">filaments</span> prevent electrical arcs by triggering corona that neutralize the high-voltage electrodes. This phenomenon, that relies on the electric field modulation and free electron release around the <span class="hlt">filament</span>, opens new prospects to lightning and over-voltage mitigation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JChPh.146o4901S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JChPh.146o4901S"><span>Spontaneous beating and synchronization of extensile active <span class="hlt">filament</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sarkar, Debarati; Thakur, Snigdha</p> <p>2017-04-01</p> <p>We simulate a semi-flexible active <span class="hlt">filament</span> that exhibits spontaneous oscillations on clamping and show self-propulsion when left free. The activity on the <span class="hlt">filament</span> relies on the nano-dimers distributed at regular intervals along the chain. With an emphasis on the spontaneous beating of a clamped <span class="hlt">filament</span>, we demonstrate that the two competing forces necessary for oscillation are the elastic forces due to polymer rigidity and the active forces due to chemical activity. In addition, we also study the synchronization of two extensile <span class="hlt">filaments</span> and the role played by non-local hydrodynamic interactions. We observe a phase lock scenario between the <span class="hlt">filaments</span> during their synchronous motion.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25322453','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25322453"><span>Hydrodynamic interaction induced spontaneous rotation of coupled active <span class="hlt">filaments</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Jiang, Huijun; Hou, Zhonghuai</p> <p>2014-12-14</p> <p>We investigate the coupled dynamics of active <span class="hlt">filaments</span> with long range hydrodynamic interactions (HI). Remarkably, we find that <span class="hlt">filaments</span> can rotate spontaneously under the same conditions in which a single <span class="hlt">filament</span> alone can only move in translation. Detailed analysis reveals that the emergence of coupled rotation originates from an asymmetric flow field associated with HI which breaks the symmetry of translational motion when <span class="hlt">filaments</span> approach. The breaking is then further stabilized by HI to form self-sustained coupled rotation. Intensive simulations show that coupled rotation forms easily when one <span class="hlt">filament</span> tends to collide with the front-half of the other. For head-to-tail approaching, we observe another interesting HI-induced coupled motion, where <span class="hlt">filaments</span> move together in the form of one following the other. Moreover, the radius of coupled rotation increases exponentially as the rigidity of the <span class="hlt">filament</span> increases, which suggests that HI are also important for the alignment of rigid-rod-like <span class="hlt">filaments</span> which has been assumed to be solely a consequence of direct collisions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/55820','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/biblio/55820"><span>Aerogel-supported <span class="hlt">filament</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Wuest, C.R.; Tillotson, T.M.; Johnson, C.V. III</p> <p>1995-05-16</p> <p>The present invention is a thin <span class="hlt">filament</span> embedded in a low density aerogel for use in radiation detection instruments and incandescent lamps. The aerogel provides a supportive matrix that is thermally and electrically nonconductive, mechanically strong, highly porous, gas-permeable, and transparent to ionizing radiation over short distances. A low density, open-cell aerogel is cast around a fine <span class="hlt">filament</span> or wire, which allows the wire to be positioned with little or no tension and keeps the wire in place in the event of breakage. The aerogel support reduces the stresses on the wire caused by vibrational, gravitational, electrical, and mechanical forces. 6 Figs.</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.osti.gov/biblio/22494772-direct-observation-conductive-filament-formation-alq3-based-organic-resistive-memories','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22494772-direct-observation-conductive-filament-formation-alq3-based-organic-resistive-memories"><span>Direct observation of conductive <span class="hlt">filament</span> formation in Alq3 based organic resistive memories</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>Busby, Y., E-mail: yan.busby@unamur.be; Pireaux, J.-J.; Nau, S.</p> <p>2015-08-21</p> <p>This work explores resistive switching mechanisms in non-volatile organic memory devices based on tris(8-hydroxyquinolie)aluminum (Alq{sub 3}). Advanced characterization tools are applied to investigate metal diffusion in ITO/Alq{sub 3}/Ag memory device stacks leading to conductive <span class="hlt">filament</span> formation. The morphology of Alq{sub 3}/Ag layers as a function of the metal evaporation conditions is studied by X-ray reflectivity, while depth profile analysis with X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry is applied to characterize operational memory elements displaying reliable bistable <span class="hlt">current</span>-voltage characteristics. 3D images of the distribution of silver inside the organic layer clearly point towards the existence of conductive filamentsmore » and allow for the identification of the initial <span class="hlt">filament</span> formation and inactivation mechanisms during switching of the device. Initial <span class="hlt">filament</span> formation is suggested to be driven by field assisted diffusion of silver from abundant structures formed during the top electrode evaporation, whereas thermochemical effects lead to local <span class="hlt">filament</span> inactivation.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24015546','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24015546"><span>[Effects of <span class="hlt">filamentous</span> macroalgae on the methane emission from urban river: a review].</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhang, Xiu-Yun; Liang, Xia; He, Chi-Quan</p> <p>2013-05-01</p> <p>The global warming caused by greenhouse gases emission has raised serious concerns. Recent studies found that the carbon dioxide (CO2) and methane (CH4) emissions from river ecosystem can partly offset the carbon sequestration by terrestrial ecosystem, leading to a rethink of the effects of river ecosystem on the global carbon balance and greenhouse gases emission inventory. As an important primary producer in urban river ecosystem, <span class="hlt">filamentous</span> macroalgae can deeply affect the carbon cycle process of river system through changing the abiotic and biotic factors in the interface of water-sediment. This paper reviewed the effects of <span class="hlt">filamentous</span> macroalgae on the CH4 emission from urban river system from the aspects of 1) the effects of urbanization on the river ecosystem and its CH4 emission flux, 2) the effects of <span class="hlt">filamentous</span> macroalgae on the CH4 generation and emission process in natural river systems, and 3) the effects of <span class="hlt">filamentous</span> macroalgae on the primary productivity and CH4 emission process in urban river systems. The <span class="hlt">current</span> problems and future directions in related researches were discussed and prospected.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22661269-star-forming-filament-models','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22661269-star-forming-filament-models"><span>Star-forming <span class="hlt">Filament</span> Models</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>Myers, Philip C., E-mail: pmyers@cfa.harvard.edu</p> <p>2017-03-20</p> <p>New models of star-forming filamentary clouds are presented in order to quantify their properties and to predict their evolution. These 2D axisymmetric models describe <span class="hlt">filaments</span> that have no core, one low-mass core, and one cluster-forming core. They are based on Plummer-like cylinders and spheroids that are bounded by a constant-density surface of finite extent. In contrast to 1D Plummer-like models, they have specific values of length and mass, they approximate observed column density maps, and their distributions of column density ( N -pdfs) are pole-free. Each model can estimate the star-forming potential of a core-<span class="hlt">filament</span> system by identifying the zonemore » of gas dense enough to form low-mass stars and by counting the number of enclosed thermal Jeans masses. This analysis suggests that the Musca central <span class="hlt">filament</span> may be near the start of its star-forming life, with enough dense gas to make its first ∼3 protostars, while the Coronet <span class="hlt">filament</span> is near the midpoint of its star formation, with enough dense gas to add ∼8 protostars to its ∼20 known stars. In contrast, L43 appears to be near the end of its star-forming life, since it lacks enough dense gas to add any new protostars to the two young stellar objectsalready known.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20080037992&hterms=planet+flux&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dplanet%2Bflux','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20080037992&hterms=planet+flux&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dplanet%2Bflux"><span>MESSENGER and Venus Express Observations of the Near-tail of Venus: Magnetic Flux Transport, <span class="hlt">Current</span> <span class="hlt">Sheet</span> Structure, and Flux Rope Formation</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>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.; <a style="text-decoration: none; " href="javascript:void(0); " onClick="displayelement('author_20080037992'); toggleEditAbsImage('author_20080037992_show'); toggleEditAbsImage('author_20080037992_hide'); "> <img style="display:inline; width:12px; height:12px; " src="images/arrow-up.gif" width="12" height="12" border="0" alt="hide" id="author_20080037992_show"> <img style="width:12px; height:12px; display:none; " src="images/arrow-down.gif" width="12" height="12" border="0" alt="hide" id="author_20080037992_hide"></p> <p>2008-01-01</p> <p>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 <span class="hlt">current</span> <span class="hlt">sheet</span> at very low altitudes (approx. 300 to 1000 km), and the nature and origin of a magnetic flux rope observed in the <span class="hlt">current</span> <span class="hlt">sheet</span>. 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4330538','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4330538"><span>Mid-infrared laser <span class="hlt">filaments</span> in the atmosphere</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Mitrofanov, A. V.; Voronin, A. A.; Sidorov-Biryukov, D. A.; Pugžlys, A.; Stepanov, E. A.; Andriukaitis, G.; Flöry, T.; Ališauskas, S.; Fedotov, A. B.; Baltuška, A.; Zheltikov, A. M.</p> <p>2015-01-01</p> <p><span class="hlt">Filamentation</span> of ultrashort laser pulses in the atmosphere offers unique opportunities for long-range transmission of high-power laser radiation and standoff detection. With the critical power of self-focusing scaling as the laser wavelength squared, the quest for longer-wavelength drivers, which would radically increase the peak power and, hence, the laser energy in a single <span class="hlt">filament</span>, has been ongoing over two decades, during which time the available laser sources limited <span class="hlt">filamentation</span> experiments in the atmosphere to the near-infrared and visible ranges. Here, we demonstrate <span class="hlt">filamentation</span> of ultrashort mid-infrared pulses in the atmosphere for the first time. We show that, with the spectrum of a femtosecond laser driver centered at 3.9 μm, right at the edge of the atmospheric transmission window, radiation energies above 20 mJ and peak powers in excess of 200 GW can be transmitted through the atmosphere in a single <span class="hlt">filament</span>. Our studies reveal unique properties of mid-infrared <span class="hlt">filaments</span>, where the generation of powerful mid-infrared supercontinuum is accompanied by unusual scenarios of optical harmonic generation, giving rise to remarkably broad radiation spectra, stretching from the visible to the mid-infrared. PMID:25687621</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29355854','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29355854"><span>Prokaryotic cytoskeletons: protein <span class="hlt">filaments</span> organizing small cells.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wagstaff, James; Löwe, Jan</p> <p>2018-04-01</p> <p>Most, if not all, bacterial and archaeal cells contain at least one protein <span class="hlt">filament</span> system. Although these <span class="hlt">filament</span> systems in some cases form structures that are very similar to eukaryotic cytoskeletons, the term 'prokaryotic cytoskeletons' is used to refer to many different kinds of protein <span class="hlt">filaments</span>. Cytoskeletons achieve their functions through polymerization of protein monomers and the resulting ability to access length scales larger than the size of the monomer. Prokaryotic cytoskeletons are involved in many fundamental aspects of prokaryotic cell biology and have important roles in cell shape determination, cell division and nonchromosomal DNA segregation. Some of the <span class="hlt">filament</span>-forming proteins have been classified into a small number of conserved protein families, for example, the almost ubiquitous tubulin and actin superfamilies. To understand what makes <span class="hlt">filaments</span> special and how the cytoskeletons they form enable cells to perform essential functions, the structure and function of cytoskeletal molecules and their <span class="hlt">filaments</span> have been investigated in diverse bacteria and archaea. In this Review, we bring these data together to highlight the diverse ways that linear protein polymers can be used to organize other molecules and structures in bacteria and archaea.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4102135','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4102135"><span>A Method for 3D-Reconstruction of a Muscle Thick <span class="hlt">Filament</span> Using the Tilt Series Images of a Single <span class="hlt">Filament</span> Electron Tomogram</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Márquez, G.; Pinto, A.; Alamo, L.; Baumann, B.; Ye, F.; Winkler, H.; Taylor, K.; Padrón, R.</p> <p>2014-01-01</p> <p>Summary Myosin interacting-heads (MIH) motifs are visualized in 3D-reconstructions of thick <span class="hlt">filaments</span> from striated muscle. These reconstructions are calculated by averaging methods using images from electron micrographs of grids prepared using numerous <span class="hlt">filament</span> preparations. Here we propose an alternative method to calculate the 3D-reconstruction of a single thick <span class="hlt">filament</span> using only a tilt series images recorded by electron tomography. Relaxed thick <span class="hlt">filaments</span>, prepared from tarantula leg muscle homogenates, were negatively stained. Single-axis tilt series of single isolated thick <span class="hlt">filaments</span> were obtained with the electron microscope at a low electron dose, and recorded on a CCD camera by electron tomography. An IHRSR 3D-recontruction was calculated from the tilt series images of a single thick <span class="hlt">filament</span>. The reconstruction was enhanced by including in the search stage dual tilt image segments while only single tilt along the <span class="hlt">filament</span> axis is usually used, as well as applying a band pass filter just before the back projection. The reconstruction from a single <span class="hlt">filament</span> has a 40 Å resolution and clearly shows the presence of MIH motifs. In contrast, the electron tomogram 3D-reconstruction of the same thick <span class="hlt">filament</span> –calculated without any image averaging and/or imposition of helical symmetry- only reveals MIH motifs infrequently. This is –to our knowledge- the first application of the IHRSR method to calculate a 3D reconstruction from tilt series images. This single <span class="hlt">filament</span> IHRSR reconstruction method (SF-IHRSR) should provide a new tool to assess structural differences between well-ordered thick (or thin) <span class="hlt">filaments</span> in a grid by recording separately their electron tomograms. PMID:24727133</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24727133','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24727133"><span>A method for 3D-reconstruction of a muscle thick <span class="hlt">filament</span> using the tilt series images of a single <span class="hlt">filament</span> electron tomogram.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Márquez, G; Pinto, A; Alamo, L; Baumann, B; Ye, F; Winkler, H; Taylor, K; Padrón, R</p> <p>2014-05-01</p> <p>Myosin interacting-heads (MIH) motifs are visualized in 3D-reconstructions of thick <span class="hlt">filaments</span> from striated muscle. These reconstructions are calculated by averaging methods using images from electron micrographs of grids prepared using numerous <span class="hlt">filament</span> preparations. Here we propose an alternative method to calculate the 3D-reconstruction of a single thick <span class="hlt">filament</span> using only a tilt series images recorded by electron tomography. Relaxed thick <span class="hlt">filaments</span>, prepared from tarantula leg muscle homogenates, were negatively stained. Single-axis tilt series of single isolated thick <span class="hlt">filaments</span> were obtained with the electron microscope at a low electron dose, and recorded on a CCD camera by electron tomography. An IHRSR 3D-recontruction was calculated from the tilt series images of a single thick <span class="hlt">filament</span>. The reconstruction was enhanced by including in the search stage dual tilt image segments while only single tilt along the <span class="hlt">filament</span> axis is usually used, as well as applying a band pass filter just before the back projection. The reconstruction from a single <span class="hlt">filament</span> has a 40 Å resolution and clearly shows the presence of MIH motifs. In contrast, the electron tomogram 3D-reconstruction of the same thick <span class="hlt">filament</span> - calculated without any image averaging and/or imposition of helical symmetry - only reveals MIH motifs infrequently. This is - to our knowledge - the first application of the IHRSR method to calculate a 3D reconstruction from tilt series images. This single <span class="hlt">filament</span> IHRSR reconstruction method (SF-IHRSR) should provide a new tool to assess structural differences between well-ordered thick (or thin) <span class="hlt">filaments</span> in a grid by recording separately their electron tomograms. Copyright © 2014 Elsevier Inc. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25517157','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25517157"><span>Direct observation of subunit exchange along mature vimentin intermediate <span class="hlt">filaments</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Nöding, Bernd; Herrmann, Harald; Köster, Sarah</p> <p>2014-12-16</p> <p>Actin <span class="hlt">filaments</span>, microtubules, and intermediate <span class="hlt">filaments</span> (IFs) are central elements of the metazoan cytoskeleton. At the molecular level, the assembly mechanism for actin <span class="hlt">filaments</span> and microtubules is fundamentally different from that of IFs. The former two types of <span class="hlt">filaments</span> assemble from globular proteins. By contrast, IFs assemble from tetrameric complexes of extended, half-staggered, and antiparallel oriented coiled-coils. These tetramers laterally associate into unit-length <span class="hlt">filaments</span>; subsequent longitudinal annealing of unit-length <span class="hlt">filaments</span> yields mature IFs. In vitro, IFs form open structures without a fixed number of tetramers per cross-section along the <span class="hlt">filament</span>. Therefore, a central question for the structural biology of IFs is whether individual subunits can dissociate from assembled <span class="hlt">filaments</span> and rebind at other sites. Using the fluorescently labeled IF-protein vimentin for assembly, we directly observe and quantitatively determine subunit exchange events between <span class="hlt">filaments</span> as well as with soluble vimentin pools. Thereby we demonstrate that the cross-sectional polymorphism of donor and acceptor <span class="hlt">filaments</span> plays an important role. We propose that in segments of donor <span class="hlt">filaments</span> with more than the standard 32 molecules per cross-section, subunits are not as tightly bound and are predisposed to be released from the <span class="hlt">filament</span>. Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.</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('http://adsabs.harvard.edu/abs/2017APS..DPPG11044K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017APS..DPPG11044K"><span>Directed high-power THz radiation from transverse laser wakefield excited in an electron density <span class="hlt">filament</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kalmykov, Serge; Englesbe, Alexander; Elle, Jennifer; Domonkos, Matthew; Schmitt-Sody, Andreas</p> <p>2017-10-01</p> <p>A tightly focused femtosecond, weakly relativistic laser pulse partially ionizes the ambient gas, creating a string (a ``<span class="hlt">filament</span>'') of electron density, locally reducing the nonlinear index and compensating for the self-focusing effect caused by bound electrons. While maintaining the <span class="hlt">filament</span> over many Rayleigh lengths, the pulse drives inside it a three-dimensional (3D) wave of charge separation - the plasma wake. If the pulse waist size is much smaller than the Langmuir wavelength, electron <span class="hlt">current</span> in the wake is mostly transverse. Electrons, driven by the wake across the sharp radial boundary of the <span class="hlt">filament</span>, lose coherence within 2-3 periods of wakefield oscillations, and the wake decays. The laser pulse is thus accompanied by a short-lived, almost aperiodic electron <span class="hlt">current</span> coupled to the sharp index gradient. The comprehensive 3D hydrodynamic model shows that this structure emits a broad-band THz radiation, with the highest power emitted in the near-forward direction. The THz radiation pattern contains information on wake <span class="hlt">currents</span> surrounding the laser pulse, thus serving as an all-optical diagnostic tool. The results are tested in cylindrical and full 3D PIC simulations using codes WAKE and EPOCH.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017APS..MARX11012W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017APS..MARX11012W"><span>Self-assembly of nematic liquid crystal elastomer <span class="hlt">filaments</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wei, Wei-Shao; Xia, Yu; Yang, Shu; Yodh, A. G.</p> <p></p> <p>In this work we investigate the self-assembly of nematic liquid crystal polymer (NLCP) <span class="hlt">filaments</span> and their corresponding cross-linked elastomer structures. Specifically, by fine-tuning surfactant concentration, prepolymer chain length, and temperature within a background aqueous phase we can generate <span class="hlt">filaments</span> composed of oligomerized LC monomers. <span class="hlt">Filaments</span> with narrowly dispersed diameters ranging from one hundred nanometers to a few micrometers can be obtained. Using polarization optical microscopy, we show that the nematic LCs within the <span class="hlt">filaments</span> have an escaped radial structure. After photo-cross-linking, nematic liquid crystal elastomer <span class="hlt">filaments</span> are obtained with well-maintained directors and smooth surface structure. Since these materials are elastomers, the size and mechanical and optical response of the <span class="hlt">filaments</span> can be ''tuned'' near the nematic to isotropic phase transition temperature. This work is supported by NSF DMR16-07378, PENN MRSEC Grant DMR11-20901, and NASA Grant NNX08AO0G.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29738832','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29738832"><span>Topology of interaction between titin and myosin thick <span class="hlt">filaments</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kellermayer, Miklós; Sziklai, Dominik; Papp, Zsombor; Decker, Brennan; Lakatos, Eszter; Mártonfalvi, Zsolt</p> <p>2018-05-05</p> <p>Titin is a giant protein spanning between the Z- and M-lines of the sarcomere. In the A-band titin is associated with the myosin thick <span class="hlt">filament</span>. It has been speculated that titin may serve as a blueprint for thick-<span class="hlt">filament</span> formation due to the super-repeat structure of its A-band domains. Accordingly, titin might provide a template that determines the length and structural periodicity of the thick <span class="hlt">filament</span>. Here we tested the titin ruler hypothesis by mixing titin and myosin at in situ stoichiometric ratios (300 myosins per 12 titins) in buffers of different ionic strength (KCl concentration range 100-300 mM). The topology of the <span class="hlt">filamentous</span> complexes was investigated with atomic force microscopy. We found that the samples contained distinct, segregated populations of titin molecules and myosin thick <span class="hlt">filaments</span>. We were unable to identify complexes in which myosin molecules were regularly associated to either mono- or oligomeric titin in either relaxed or stretched states of the titin <span class="hlt">filaments</span>. Thus, the electrostatically driven self-association is stronger in both myosin and titin than their binding to each other, and it is unlikely that titin functions as a geometrical template for thick-<span class="hlt">filament</span> formation. However, when allowed to equilibrate configurationally, long myosin thick <span class="hlt">filaments</span> appeared with titin oligomers attached to their surface. The titin meshwork formed on the thick-<span class="hlt">filament</span> surface may play a role in controlling thick-<span class="hlt">filament</span> length by regulating the structural dynamics of myosin molecules and placing a mechanical limit on the <span class="hlt">filament</span> length. Copyright © 2018 Elsevier Inc. All rights reserved.</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('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 tail axis and tail 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/2017JPCM...29o3002M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JPCM...29o3002M"><span>Physical principles of <span class="hlt">filamentous</span> protein self-assembly kinetics</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Michaels, Thomas C. T.; Liu, Lucie X.; Meisl, Georg; Knowles, Tuomas P. J.</p> <p>2017-04-01</p> <p>The polymerization of proteins and peptides into <span class="hlt">filamentous</span> supramolecular structures is an elementary form of self-organization of key importance to the functioning biological systems, as in the case of actin biofilaments that compose the cellular cytoskeleton. Aberrant <span class="hlt">filamentous</span> protein self-assembly, however, is associated with undesired effects and severe clinical disorders, such as Alzheimer’s and Parkinson’s diseases, which, at the molecular level, are associated with the formation of certain forms of <span class="hlt">filamentous</span> protein aggregates known as amyloids. Moreover, due to their unique physicochemical properties, protein <span class="hlt">filaments</span> are finding extensive applications as biomaterials for nanotechnology. With all these different factors at play, the field of <span class="hlt">filamentous</span> protein self-assembly has experienced tremendous activity in recent years. A key question in this area has been to elucidate the microscopic mechanisms through which <span class="hlt">filamentous</span> aggregates emerge from dispersed proteins with the goal of uncovering the underlying physical principles. With the latest developments in the mathematical modeling of protein aggregation kinetics as well as the improvement of the available experimental techniques it is now possible to tackle many of these complex systems and carry out detailed analyses of the underlying microscopic steps involved in protein <span class="hlt">filament</span> formation. In this paper, we review some classical and modern kinetic theories of protein <span class="hlt">filament</span> formation, highlighting their use as a general strategy for quantifying the molecular-level mechanisms and transition states involved in these processes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PhPl...24j2115I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PhPl...24j2115I"><span>Computational studies on scattering of radio frequency waves by density <span class="hlt">filaments</span> in fusion plasmas</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ioannidis, Zisis C.; Ram, Abhay K.; Hizanidis, Kyriakos; Tigelis, Ioannis G.</p> <p>2017-10-01</p> <p>In modern magnetic fusion devices, such as tokamaks and stellarators, radio frequency (RF) waves are commonly used for plasma heating and <span class="hlt">current</span> profile control, as well as for certain diagnostics. The frequencies of the RF waves range from ion cyclotron frequency to the electron cyclotron frequency. The RF waves are launched from structures, like waveguides and <span class="hlt">current</span> straps, placed near the wall in a very low density, tenuous plasma region of a fusion device. The RF electromagnetic fields have to propagate through this scrape-off layer before coupling power to the core of the plasma. The scrape-off layer is characterized by turbulent plasmas fluctuations and by blobs and <span class="hlt">filaments</span>. The variations in the edge density due to these fluctuations and <span class="hlt">filaments</span> can affect the propagation characteristics of the RF waves—changes in density leading to regions with differing plasma permittivity. Analytical full-wave theories have shown that scattering by blobs and <span class="hlt">filaments</span> can alter the RF power flow into the core of the plasma in a variety of ways, such as through reflection, refraction, diffraction, and shadowing [see, for example, Ram and Hizanidis, Phys. Plasmas 23, 022504 (2016), and references therein]. There are changes in the wave vectors and the distribution of power-scattering leading to coupling of the incident RF wave to other plasma waves, side-scattering, surface waves, and fragmentation of the Poynting flux in the direction towards the core. However, these theoretical models are somewhat idealized. In particular, it is assumed that there is step-function discontinuity in the density between the plasma inside the <span class="hlt">filament</span> and the background plasma. In this paper, results from numerical simulations of RF scattering by <span class="hlt">filaments</span> using a commercial full-wave code are described. The <span class="hlt">filaments</span> are taken to be cylindrical with the axis of the cylinder aligned along the direction of the ambient magnetic field. The plasma inside and outside the <span class="hlt">filament</span> is</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25889626','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25889626"><span>Testing a dual-fluorescence assay to monitor the viability of <span class="hlt">filamentous</span> cyanobacteria.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Johnson, Tylor J; Hildreth, Michael B; Gu, Liping; Zhou, Ruanbao; Gibbons, William R</p> <p>2015-06-01</p> <p><span class="hlt">Filamentous</span> cyanobacteria are <span class="hlt">currently</span> being engineered to produce long-chain organic compounds, including 3rd generation biofuels. Because of their <span class="hlt">filamentous</span> morphology, standard methods to quantify viability (e.g., plate counts) are not possible. This study investigated a dual-fluorescence assay based upon the LIVE/DEAD® BacLight™ Bacterial Viability Kit to quantify the percent viability of <span class="hlt">filamentous</span> cyanobacteria using a microplate reader in a high throughput 96-well plate format. The manufacturer's protocol calls for an optical density normalization step to equalize the numbers of viable and non-viable cells used to generate calibration curves. Unfortunately, the isopropanol treatment used to generate non-viable cells released a blue pigment that altered absorbance readings of the non-viable cell solution, resulting in an inaccurate calibration curve. Thus we omitted this optical density normalization step, and carefully divided cell cultures into two equal fractions before the isopropanol treatment. While the resulting calibration curves had relatively high correlation coefficients, their use in various experiments resulted in viability estimates ranging from below 0% to far above 100%. We traced this to the apparent inaccuracy of the propidium iodide (PI) dye that was to stain only non-viable cells. Through further analysis via microplate reader, as well as confocal and wide-field epi-fluorescence microscopy, we observed non-specific binding of PI in viable <span class="hlt">filamentous</span> cyanobacteria. While PI will not work for <span class="hlt">filamentous</span> cyanobacteria, it is possible that other fluorochrome dyes could be used to selectively stain non-viable cells. This will be essential in future studies for screening mutants and optimizing photobioreactor system performance for <span class="hlt">filamentous</span> cyanobacteria. Copyright © 2015 Elsevier B.V. All rights reserved.</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('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5895109','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5895109"><span>Direct observation of the actin <span class="hlt">filament</span> by tip-scan atomic force microscopy</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Narita, Akihiro; Usukura, Eiji; Yagi, Akira; Tateyama, Kiyohiko; Akizuki, Shogo; Kikumoto, Mahito; Matsumoto, Tomoharu; Maéda, Yuichiro; Ito, Shuichi; Usukura, Jiro</p> <p>2016-01-01</p> <p>Actin <span class="hlt">filaments</span>, the actin–myosin complex and the actin–tropomyosin complex were observed by a tip-scan atomic force microscope (AFM), which was recently developed by Olympus as the AFM part of a correlative microscope. This newly developed AFM uses cantilevers of similar size as stage-scan AFMs to improve substantially the spatial and temporal resolution. Such an approach has previously never been possible by a tip-scan system, in which a cantilever moves in the x, y and z directions. We evaluated the performance of this developed tip-scan AFM by observing the molecular structure of actin <span class="hlt">filaments</span> and the actin–tropomyosin complex. In the image of the actin <span class="hlt">filament</span>, the molecular interval of the actin subunits (∼5.5 nm) was clearly observed as stripes. From the shape of the stripes, the polarity of the actin <span class="hlt">filament</span> was directly determined and the results were consistent with the polarity determined by myosin binding. In the image of the actin–tropomyosin complex, each tropomyosin molecule (∼2 nm in diameter) on the actin <span class="hlt">filament</span> was directly observed without averaging images of different molecules. Each tropomyosin molecule on the actin <span class="hlt">filament</span> has never been directly observed by AFM or electron microscopy. Thus, our developed tip-scan AFM offers significant potential in observing purified proteins and cellular structures at nanometer resolution. <span class="hlt">Current</span> results represent an important step in the development of a new correlative microscope to observe nm-order structures at an acceptable frame rate (∼10 s/frame) by AFM at the position indicated by the fluorescent dye observed under a light microscope. PMID:27242058</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018A%26A...610A..62C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018A%26A...610A..62C"><span>On the fragmentation of <span class="hlt">filaments</span> in a molecular cloud simulation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chira, R.-A.; Kainulainen, J.; Ibáñez-Mejía, J. C.; Henning, Th.; Mac Low, M.-M.</p> <p>2018-03-01</p> <p>Context. The fragmentation of <span class="hlt">filaments</span> in molecular clouds has attracted a lot of attention recently as there seems to be a close relation between the evolution of <span class="hlt">filaments</span> and star formation. The study of the fragmentation process has been motivated by simple analytical models. However, only a few comprehensive studies have analysed the evolution of <span class="hlt">filaments</span> using numerical simulations where the <span class="hlt">filaments</span> form self-consistently as part of large-scale molecular cloud evolution. Aim. We address the early evolution of parsec-scale <span class="hlt">filaments</span> that form within individual clouds. In particular, we focus on three questions: How do the line masses of <span class="hlt">filaments</span> evolve? How and when do the <span class="hlt">filaments</span> fragment? How does the fragmentation relate to the line masses of the <span class="hlt">filaments</span>? Methods: We examine three simulated molecular clouds formed in kiloparsec-scale numerical simulations performed with the FLASH adaptive mesh refinement magnetohydrodynamic code. The simulations model a self-gravitating, magnetised, stratified, supernova-driven interstellar medium, including photoelectric heating and radiative cooling. We follow the evolution of the clouds for 6 Myr from the time self-gravity starts to act. We identify <span class="hlt">filaments</span> using the DisPerSe algorithm, and compare the results to other <span class="hlt">filament</span>-finding algorithms. We determine the properties of the identified <span class="hlt">filaments</span> and compare them with the predictions of analytic <span class="hlt">filament</span> stability models. Results: The average line masses of the identified <span class="hlt">filaments</span>, as well as the fraction of mass in filamentary structures, increases fairly continuously after the onset of self-gravity. The <span class="hlt">filaments</span> show fragmentation starting relatively early: the first fragments appear when the line masses lie well below the critical line mass of Ostriker's isolated hydrostatic equilibrium solution ( 16 M⊙ pc-1), commonly used as a fragmentation criterion. The average line masses of <span class="hlt">filaments</span> identified in three-dimensional volume density cubes</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMSH31B2572P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMSH31B2572P"><span>Flux Cancellation Leading to Solar <span class="hlt">Filament</span> Eruptions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Popescu, R. M.; Panesar, N. K.; Sterling, A. C.; Moore, R. L.</p> <p>2016-12-01</p> <p>Solar <span class="hlt">filaments</span> are strands of relatively cool, dense plasma magnetically suspended in the lower density hotter solar corona. They trace magnetic polarity inversion lines (PILs) in the photosphere below, and are supported against gravity at heights of up to 100 Mm above the chromosphere by the magnetic field in and around them. This field erupts when it is rendered unstable by either magnetic flux cancellation or emergence at or near the PIL. We have studied the evolution of photospheric magnetic flux leading to ten observed <span class="hlt">filament</span> eruptions. Specifically, we look for gradual magnetic changes in the neighborhood of the PIL prior to and during eruption. We use Extreme Ultraviolet (EUV) images from the Atmospheric Imaging Assembly (AIA), and magnetograms from the Helioseismic and Magnetic Imager (HMI), both onboard the Solar Dynamics Observatory (SDO), to study <span class="hlt">filament</span> eruptions and their photospheric magnetic fields. We examine whether flux cancellation or/and emergence leads to <span class="hlt">filament</span> eruptions and find that continuous flux cancellation was present at the PIL for many hours prior to each eruption. We present two events in detail and find the following: (a) the pre-eruption <span class="hlt">filament</span>-holding core field is highly sheared and appears in the shape of a sigmoid above the PIL; (b) at the start of the eruption the opposite arms of the sigmoid reconnect in the middle above the site of (tether-cutting) flux cancellation at the PIL; (c) the <span class="hlt">filaments</span> first show a slow-rise, followed by a fast-rise as they erupt. We conclude that these two <span class="hlt">filament</span> eruptions result from flux cancellation in the middle of the sheared field and are in agreement with the standard model for a CME/flare <span class="hlt">filament</span> eruption from a closed bipolar magnetic field [flux cancellation (van Ballegooijen and Martens 1989 and Moore and Roumelrotis 1992) and runaway tether-cutting (Moore et. al 2001)].</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20160014832','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20160014832"><span>Flux Cancellation Leading to CME <span class="hlt">Filament</span> Eruptions</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Popescu, Roxana M.; Panesar, Navdeep K.; Sterling, Alphonse C.; Moore, Ronald L.</p> <p>2016-01-01</p> <p>Solar <span class="hlt">filaments</span> are strands of relatively cool, dense plasma magnetically suspended in the lower density hotter solar corona. They trace magnetic polarity inversion lines (PILs) in the photosphere below, and are supported against gravity at heights of up to approx.100 Mm above the chromosphere by the magnetic field in and around them. This field erupts when it is rendered unstable, often by magnetic flux cancellation or emergence at or near the PIL. We have studied the evolution of photospheric magnetic flux leading to ten observed <span class="hlt">filament</span> eruptions. Specifically, we look for gradual magnetic changes in the neighborhood of the PIL prior to and during eruption. We use Extreme Ultraviolet (EUV) images from the Atmospheric Imaging Assembly (AIA), and magnetograms from the Helioseismic and Magnetic Imager (HMI), both on board the Solar Dynamics Observatory (SDO), to study <span class="hlt">filament</span> eruptions and their photospheric magnetic fields. We examine whether flux cancellation or/and emergence leads to <span class="hlt">filament</span> eruptions. We find that continuous flux cancellation was present at the PIL for many hours prior to each eruption. We present two CME-producing eruptions in detail and find the following: (a) the pre-eruption <span class="hlt">filament</span>-holding core field is highly sheared and appears in the shape of a sigmoid above the PIL; (b) at the start of the eruption the opposite arms of the sigmoid reconnect in the middle above the site of (tether-cutting) flux cancellation at the PIL; (c) the <span class="hlt">filaments</span> first show a slow-rise, followed by a fast-rise as they erupt. We conclude that these two <span class="hlt">filament</span> eruptions result from flux cancellation in the middle of the sheared field, and thereafter evolve in agreement with the standard model for a CME/flare <span class="hlt">filament</span> eruption from a closed bipolar magnetic field [flux cancellation (van Ballegooijen and Martens 1989 and Moore and Roumelrotis 1992) and runaway tether-cutting (Moore et. al 2001)].</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3127193','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3127193"><span>Cofilin-Linked Changes in Actin <span class="hlt">Filament</span> Flexibility Promote Severing</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>McCullough, Brannon R.; Grintsevich, Elena E.; Chen, Christine K.; Kang, Hyeran; Hutchison, Alan L.; Henn, Arnon; Cao, Wenxiang; Suarez, Cristian; Martiel, Jean-Louis; Blanchoin, Laurent; Reisler, Emil; De La Cruz, Enrique M.</p> <p>2011-01-01</p> <p>The actin regulatory protein, cofilin, increases the bending and twisting elasticity of actin <span class="hlt">filaments</span> and severs them. It has been proposed that <span class="hlt">filaments</span> partially decorated with cofilin accumulate stress from thermally driven shape fluctuations at bare (stiff) and decorated (compliant) boundaries, thereby promoting severing. This mechanics-based severing model predicts that changes in actin <span class="hlt">filament</span> compliance due to cofilin binding affect severing activity. Here, we test this prediction by evaluating how the severing activities of vertebrate and yeast cofilactin scale with the flexural rigidities determined from analysis of shape fluctuations. Yeast actin <span class="hlt">filaments</span> are more compliant in bending than vertebrate actin <span class="hlt">filaments</span>. Severing activities of cofilactin isoforms correlate with changes in <span class="hlt">filament</span> flexibility. Vertebrate cofilin binds but does not increase the yeast actin <span class="hlt">filament</span> flexibility, and does not sever them. Imaging of <span class="hlt">filament</span> thermal fluctuations reveals that severing events are associated with local bending and fragmentation when deformations attain a critical angle. The critical severing angle at boundaries between bare and cofilin-decorated segments is smaller than in bare or fully decorated <span class="hlt">filaments</span>. These measurements support a cofilin-severing mechanism in which mechanical asymmetry promotes local stress accumulation and fragmentation at boundaries of bare and cofilin-decorated segments, analogous to failure of some nonprotein materials. PMID:21723825</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016A%26A...589A..31B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016A%26A...589A..31B"><span>Formation of a solar Hα <span class="hlt">filament</span> from orphan penumbrae</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Buehler, D.; Lagg, A.; van Noort, M.; Solanki, S. K.</p> <p>2016-05-01</p> <p>Aims: The formation and evolution of an Hα <span class="hlt">filament</span> in active region (AR) 10953 is described. Methods: Observations from the Solar Optical Telescope (SOT) aboard the Hinode satellite starting from UT 18:09 on 27th April 2007 until UT 06:08 on 1st May 2007 were analysed. 20 scans of the 6302 Å Fe I line pair recorded by SOT/SP were inverted using the spatially coupled version of the SPINOR code. The inversions were analysed together with co-spatial SOT/BFI G-band and Ca II H and SOT/NFI Hα observations. Results: Following the disappearance of an initial Hα <span class="hlt">filament</span> aligned along the polarity inversion line (PIL) of the AR, a new Hα <span class="hlt">filament</span> formed in its place some 20 h later, which remained stable for, at least, another 1.5 days. The creation of the new Hα <span class="hlt">filament</span> was driven by the ascent of horizontal magnetic fields from the photosphere into the chromosphere at three separate locations along the PIL. The magnetic fields at two of these locations were situated directly underneath the initial Hα <span class="hlt">filament</span> and formed orphan penumbrae already aligned along the Hα <span class="hlt">filament</span> channel. The 700 G orphan penumbrae were stable and trapped in the photosphere until the disappearance of the overlying initial Hα <span class="hlt">filament</span>, after which they started to ascend into the chromosphere at 10 ± 5 m/s. Each ascent was associated with a simultaneous magnetic flux reduction of up to 50% in the photosphere. The ascended orphan penumbrae formed dark seed structures in Hα in parallel with the PIL, which elongated and merged to form an Hα <span class="hlt">filament</span>. The <span class="hlt">filament</span> channel featured horizontal magnetic fields of on average 260 G at log (τ) = -2 suspended above the nearly field-free lower photosphere. The fields took on an overall inverse configuration at log (τ) = -2 suggesting a flux rope topology for the new Hα <span class="hlt">filament</span>. The destruction of the initial Hα <span class="hlt">filament</span> was likely caused by the flux emergence at the third location along the PIL. Conclusions: We present a new</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/269254','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/269254"><span>Importance of <span class="hlt">filament</span> diameter when using bass brushing technique.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Vowles, A D; Wade, A B</p> <p>1977-08-01</p> <p>A comparative study using a crossover experimental construction was made of the effectiveness of brushes containing 6/10 nylon <span class="hlt">filaments</span> of 0.132 mm mean diameter using a Bass technique with those containing <span class="hlt">filaments</span> of the same type of nylon but 0.280 mm diameter. Each type of brush was used for a 2-week period. Even though the finer <span class="hlt">filament</span> brushes contained more than three times as many <span class="hlt">filaments</span>, they were inferior in cleaning achievement to the brushes with the broader <span class="hlt">filaments</span>. The difference was particularly marked on the facial aspect, but was largely nullified lingually. The effectiveness of the Bass technique in the gingival zone demonstrated in a previous investigation when brushes containing <span class="hlt">filaments</span> of 0.18 and 0.20 mm were used, was not found in this investigation. It is concluded that <span class="hlt">filament</span> diameter is critical in achieving effective cleaning using the Bass technique.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/863345','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/863345"><span>Method for preparing metallated <span class="hlt">filament</span>-wound structures</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Peterson, George R.</p> <p>1979-01-01</p> <p>Metallated graphite <span class="hlt">filament</span>-wound structures are prepared by coating a continuous multi-<span class="hlt">filament</span> carbon yarn with a metal carbide, impregnating the carbide coated yarn with a polymerizable carbon precursor, winding the resulting <span class="hlt">filament</span> about a mandrel, partially curing the impregnation in air, subjecting the wound composite to heat and pressure to cure the carbon precursor, and thereafter heating the composite in a sizing die at a pressure loading of at least 1000 psi for graphitizing the carbonaceous material in the composite. The carbide in the composite coalesces into rod-like shapes which are disposed in an end-to-end relationship parallel with the <span class="hlt">filaments</span> to provide resistance to erosion in abrasive laden atmospheres.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26480079','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26480079"><span>Beam wandering of femtosecond laser <span class="hlt">filament</span> in air.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Yang, Jing; Zeng, Tao; Lin, Lie; Liu, Weiwei</p> <p>2015-10-05</p> <p>The spatial wandering of a femtosecond laser <span class="hlt">filament</span> caused by the <span class="hlt">filament</span> heating effect in air has been studied. An empirical formula has also been derived from the classical Karman turbulence model, which determines quantitatively the displacement of the beam center as a function of the propagation distance and the effective turbulence structure constant. After fitting the experimental data with this formula, the effective turbulence structure constant has been estimated for a single <span class="hlt">filament</span> generated in laboratory environment. With this result, one may be able to estimate quantitatively the displacement of a <span class="hlt">filament</span> over long distance propagation and interpret the practical performance of the experiments assisted by femtosecond laser <span class="hlt">filamentation</span>, such as remote air lasing, pulse compression, high order harmonic generation (HHG), etc.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23030995','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23030995"><span>Scroll wave <span class="hlt">filaments</span> self-wrap around unexcitable heterogeneities.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Jiménez, Zulma A; Steinbock, Oliver</p> <p>2012-09-01</p> <p>Scroll waves are three-dimensional excitation vortices rotating around one-dimensional phase singularities called <span class="hlt">filaments</span>. In experiments with a chemical reaction-diffusion system and in numerical simulations, we study the pinning of closed <span class="hlt">filament</span> loops to inert cylindrical heterogeneities. We show that the <span class="hlt">filament</span> wraps itself around the heterogeneity and thus avoids contraction and annihilation. This entwining steadily increases the total length of the pinned <span class="hlt">filament</span> and reshapes the entire rotation backbone of the vortex. Self-pinning is fastest for thin cylinders with radii not much larger than the core of the unpinned rotor. The process ends when the <span class="hlt">filament</span> is attached to the entire length of the cylinder. The possible importance of self-pinning in cardiac systems is discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018Nanot..29z5202N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018Nanot..29z5202N"><span>Dimensional quantization effects in the thermodynamics of conductive <span class="hlt">filaments</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Niraula, D.; Grice, C. R.; Karpov, V. G.</p> <p>2018-06-01</p> <p>We consider the physical effects of dimensional quantization in conductive <span class="hlt">filaments</span> that underlie operations of some modern electronic devices. We show that, as a result of quantization, a sufficiently thin <span class="hlt">filament</span> acquires a positive charge. Several applications of this finding include the host material polarization, the stability of <span class="hlt">filament</span> constrictions, the equilibrium <span class="hlt">filament</span> radius, polarity in device switching, and quantization of conductance.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29648548','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29648548"><span>Dimensional quantization effects in the thermodynamics of conductive <span class="hlt">filaments</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Niraula, D; Grice, C R; Karpov, V G</p> <p>2018-06-29</p> <p>We consider the physical effects of dimensional quantization in conductive <span class="hlt">filaments</span> that underlie operations of some modern electronic devices. We show that, as a result of quantization, a sufficiently thin <span class="hlt">filament</span> acquires a positive charge. Several applications of this finding include the host material polarization, the stability of <span class="hlt">filament</span> constrictions, the equilibrium <span class="hlt">filament</span> radius, polarity in device switching, and quantization of conductance.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1249330-propagation-distance-resolved-characteristics-filament-induced-copper-plasma','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1249330-propagation-distance-resolved-characteristics-filament-induced-copper-plasma"><span>Propagation distance-resolved characteristics of <span class="hlt">filament</span>-induced copper plasma</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Ghebregziabher, Isaac; Hartig, Kyle C.; Jovanovic, Igor</p> <p>2016-03-02</p> <p>Copper plasma generated at different <span class="hlt">filament</span>-copper interaction points was characterized by spectroscopic, acoustic, and imaging measurements. The longitudinal variation of the <span class="hlt">filament</span> intensity was qualitatively determined by acoustic measurements in air. The maximum plasma temperature was measured at the location of peak <span class="hlt">filament</span> intensity, corresponding to the maximum mean electron energy during plasma formation. The highest copper plasma density was measured past the location of the maximum electron density in the <span class="hlt">filament</span>, where spectral broadening of the <span class="hlt">filament</span> leads to enhanced ionization. Acoustic measurements in air and on solid target were correlated to reconstructed plasma properties. Lastly, optimal line emissionmore » is measured near the geometric focus of the lens used to produce the <span class="hlt">filament</span>.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4248277','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4248277"><span>Transition from linear- to nonlinear-focusing regime in <span class="hlt">filamentation</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>Lim, Khan; Durand, Magali; Baudelet, Matthieu; Richardson, Martin</p> <p>2014-01-01</p> <p>Laser <span class="hlt">filamentation</span> in gases is often carried out in the laboratory with focusing optics to better stabilize the <span class="hlt">filament</span>, whereas real-world applications of <span class="hlt">filaments</span> frequently involve collimated or near-collimated beams. It is well documented that geometrical focusing can alter the properties of laser <span class="hlt">filaments</span> and, consequently, a transition between a collimated and a strongly focused <span class="hlt">filament</span> is expected. Nevertheless, this transition point has not been identified. Here, we propose an analytical method to determine the transition, and show that it corresponds to an actual shift in the balance of physical mechanisms governing <span class="hlt">filamentation</span>. In high-NA conditions, <span class="hlt">filamentation</span> is primarily governed by geometrical focusing and plasma effects, while the Kerr nonlinearity plays a more significant role as NA decreases. We find the transition between the two regimes to be relatively insensitive to the intrinsic laser parameters, and our analysis agrees well with a wide range of parameters found in published literature. PMID:25434678</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22518726-complex-flare-dynamics-initiated-filamentfilament-interaction','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22518726-complex-flare-dynamics-initiated-filamentfilament-interaction"><span>COMPLEX FLARE DYNAMICS INITIATED BY A FILAMENT–<span class="hlt">FILAMENT</span> INTERACTION</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>Zhu, Chunming; McAteer, R. T. James; Liu, Rui</p> <p>2015-11-01</p> <p>We report on an eruption involving a relatively rare filament–<span class="hlt">filament</span> interaction on 2013 June 21, observed by SDO and STEREO-B. The two <span class="hlt">filaments</span> were separated in height with a “double-decker” configuration. The eruption of the lower <span class="hlt">filament</span> began simultaneously with a descent of the upper <span class="hlt">filament</span>, resulting in a convergence and direct interaction of the two <span class="hlt">filaments</span>. The interaction was accompanied by the heating of surrounding plasma and an apparent crossing of a loop-like structure through the upper <span class="hlt">filament</span>. The subsequent coalescence of the <span class="hlt">filaments</span> drove a bright front ahead of the erupting structures. The whole process was associated withmore » a C3.0 flare followed immediately by an M2.9 flare. Shrinking loops and descending dark voids were observed during the M2.9 flare at different locations above a C-shaped flare arcade as part of the energy release, giving us unique insight into the flare dynamics.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018OptCo.412..161Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018OptCo.412..161Z"><span>Spatial evolution of laser <span class="hlt">filaments</span> in turbulent air</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zeng, Tao; Zhu, Shiping; Zhou, Shengling; He, Yan</p> <p>2018-04-01</p> <p>In this study, the spatial evolution properties of laser <span class="hlt">filament</span> clusters in turbulent air were evaluated using numerical simulations. Various statistical parameters were calculated, such as the percolation probability, filling factor, and average cluster size. The results indicate that turbulence-induced multi-<span class="hlt">filamentation</span> can be described as a new phase transition universality class. In addition, during this process, the relationship between the average cluster size and filling factor could be fit by a power function. Our results are valuable for applications involving <span class="hlt">filamentation</span> that can be influenced by the geometrical features of multiple <span class="hlt">filaments</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014cosp...40E2926S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014cosp...40E2926S"><span>Proper horizontal photospheric flows below an eruptive <span class="hlt">filament</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schmieder, Brigitte; Mein, Pierre; Mein, Nicole; Roudier, Thierry; Chandra, Ramseh</p> <p></p> <p>An analysis of the proper motions using SDO/HMI continuum images with the new version of the coherent structure tracking (CST) algorithm developed to track the granules as well as the large scale photospheric flows, was perfomed during three hours in a region containing a large <span class="hlt">filament</span> channel on September 17, 2010. Supergranules were idenfied in the <span class="hlt">filament</span> channel. Diverging flows inside the supergranules are similar in and out the <span class="hlt">filament</span> channel. Using corks, we derived the passive scalar points and produced maps of cork distribution. The anchorage structures with the photosphere (feet) of the <span class="hlt">filament</span> are located in the areas of converging flows with accumulations of corks. Averaging the velocity vectors for each latitude we defined a profile of the differential rotation. We conclude that the coupling between the convection and magnetic field in the photosphere is relatively strong. The <span class="hlt">filament</span> experienced the convection motions through its feet. On a large scale point-of-view the differential rotation induced a shear of 0.1 km/s in the <span class="hlt">filament</span>. On a small scale point-of-view convection motions favored the interaction/cancellation of the parasitic polarities at the base of the feet with the surrounding network explaining the brightenings,/jets and the eruption that were observed in the EUV <span class="hlt">filament</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3696749','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3696749"><span>Measuring the regulation of keratin <span class="hlt">filament</span> network dynamics</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Moch, Marcin; Herberich, Gerlind; Aach, Til; Leube, Rudolf E.; Windoffer, Reinhard</p> <p>2013-01-01</p> <p>The organization of the keratin intermediate <span class="hlt">filament</span> cytoskeleton is closely linked to epithelial function. To study keratin network plasticity and its regulation at different levels, tools are needed to localize and measure local network dynamics. In this paper, we present image analysis methods designed to determine the speed and direction of keratin <span class="hlt">filament</span> motion and to identify locations of keratin <span class="hlt">filament</span> polymerization and depolymerization at subcellular resolution. Using these methods, we have analyzed time-lapse fluorescence recordings of fluorescent keratin 13 in human vulva carcinoma-derived A431 cells. The fluorescent keratins integrated into the endogenous keratin cytoskeleton, and thereby served as reliable markers of keratin dynamics. We found that increased times after seeding correlated with down-regulation of inward-directed keratin <span class="hlt">filament</span> movement. Bulk flow analyses further revealed that keratin <span class="hlt">filament</span> polymerization in the cell periphery and keratin depolymerization in the more central cytoplasm were both reduced. Treating these cells and other human keratinocyte-derived cells with EGF reversed all these processes within a few minutes, coinciding with increased keratin phosphorylation. These results highlight the value of the newly developed tools for identifying modulators of keratin <span class="hlt">filament</span> network dynamics and characterizing their mode of action, which, in turn, contributes to understanding the close link between keratin <span class="hlt">filament</span> network plasticity and epithelial physiology. PMID:23757496</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('http://adsabs.harvard.edu/abs/2017PhRvF...2l3101M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PhRvF...2l3101M"><span>Bundling of elastic <span class="hlt">filaments</span> induced by hydrodynamic interactions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Man, Yi; Page, William; Poole, Robert J.; Lauga, Eric</p> <p>2017-12-01</p> <p>Peritrichous bacteria swim in viscous fluids by rotating multiple helical flagellar <span class="hlt">filaments</span>. As the bacterium swims forward, all its flagella rotate in synchrony behind the cell in a tight helical bundle. When the bacterium changes its direction, the flagellar <span class="hlt">filaments</span> unbundle and randomly reorient the cell for a short period of time before returning to their bundled state and resuming swimming. This rapid bundling and unbundling is, at its heart, a mechanical process whereby hydrodynamic interactions balance with elasticity to determine the time-varying deformation of the <span class="hlt">filaments</span>. Inspired by this biophysical problem, we present in this paper what is perhaps the simplest model of bundling whereby two or more straight elastic <span class="hlt">filaments</span> immersed in a viscous fluid rotate about their centerline, inducing rotational flows which tend to bend the <span class="hlt">filaments</span> around each other. We derive an integrodifferential equation governing the shape of the <span class="hlt">filaments</span> resulting from mechanical balance in a viscous fluid at low Reynolds number. We show that such equation may be evaluated asymptotically analytically in the long-wavelength limit, leading to a local partial differential equation governed by a single dimensionless bundling number. A numerical study of the dynamics predicted by the model reveals the presence of two configuration instabilities with increasing bundling numbers: first to a crossing state where <span class="hlt">filaments</span> touch at one point and then to a bundled state where <span class="hlt">filaments</span> wrap along each other in a helical fashion. We also consider the case of multiple <span class="hlt">filaments</span> and the unbundling dynamics. We next provide an intuitive physical model for the crossing instability and show that it may be used to predict analytically its threshold and adapted to address the transition to a bundling state. We then use a macroscale experimental implementation of the two-<span class="hlt">filament</span> configuration in order to validate our theoretical predictions and obtain excellent agreement. This long</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('https://www.ncbi.nlm.nih.gov/pubmed/16843490','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/16843490"><span>Energetics and kinetics of cooperative cofilin-actin <span class="hlt">filament</span> interactions.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Cao, Wenxiang; Goodarzi, Jim P; De La Cruz, Enrique M</p> <p>2006-08-11</p> <p>We have evaluated the thermodynamic parameters associated with cooperative cofilin binding to actin <span class="hlt">filaments</span>, accounting for contributions of ion-linked equilibria, and determined the kinetic basis of cooperative cofilin binding. Ions weaken non-contiguous (isolated, non-cooperative) cofilin binding to an actin <span class="hlt">filament</span> without affecting cooperative <span class="hlt">filament</span> interactions. Non-contiguous cofilin binding is coupled to the dissociation of approximately 1.7 thermodynamically bound counterions. Counterion dissociation contributes approximately 40% of the total cofilin binding free energy (in the presence of 50 mM KCl). The non-contiguous and cooperative binding free energies are driven entirely by large, positive entropy changes, consistent with a cofilin-mediated increase in actin <span class="hlt">filament</span> structural dynamics. The rate constant for cofilin binding to an isolated site on an actin <span class="hlt">filament</span> is slow and likely to be limited by <span class="hlt">filament</span> breathing. Cooperative cofilin binding arises from an approximately tenfold more rapid association rate constant and an approximately twofold slower dissociation rate constant. The more rapid association rate constant is presumably a consequence of cofilin-dependent changes in the average orientation of subdomain 2, subunit angular disorder and <span class="hlt">filament</span> twist, which increase the accessibility of a neighboring cofilin-binding site on an actin <span class="hlt">filament</span>. Cooperative association is more rapid than binding to an isolated site, but still slow for a second-order reaction, suggesting that cooperative binding is limited also by binding site accessibility. We suggest that the dissociation of actin-associated ions weakens intersubunit interactions in the actin <span class="hlt">filament</span> lattice that enhance cofilin-binding site accessibility, favor cooperative binding and promote <span class="hlt">filament</span> severing.</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/2015IAUGA..2257985W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015IAUGA..2257985W"><span>Large scale <span class="hlt">filaments</span> associated with Milky Way spiral arms</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, Ke; Testi, Leonardo; Ginsburg, Adam; Walmsley, Malcolm; Molinari, Sergio; Schisano, Eugenio</p> <p>2015-08-01</p> <p>The ubiquity of filamentary structure at various scales through out the Galaxy has triggered a renewed interest in their formation, evolution, and role in star formation. The largest <span class="hlt">filaments</span> can reach up to Galactic scale as part of the spiral arm structure. However, such large scale <span class="hlt">filaments</span> are hard to identify systematically due to limitations in identifying methodology (i.e., as extinction features). We present a new approach to directly search for the largest, coldest, and densest <span class="hlt">filaments</span> in the Galaxy, making use of sensitive Herschel Hi-GAL data complemented by spectral line cubes. We present a sample of the 9 most prominent Herschel <span class="hlt">filaments</span> from a pilot search field. These <span class="hlt">filaments</span> measure 37-99 pc long and 0.6-3.0 pc wide with masses (0.5-8.3)×104 Msun, and beam-averaged (28", or 0.4-0.7 pc) peak H2 column densities of (1.7-9.3)x1022 cm-2. The bulk of the <span class="hlt">filaments</span> are relatively cold (17-21 K), while some local clumps have a dust temperature up to 25-47 K due to local star formation activities. All the <span class="hlt">filaments</span> are located within <~60 pc from the Galactic mid-plane. Comparing the <span class="hlt">filaments</span> to a recent spiral arm model incorporating the latest parallax measurements, we find that 7/9 of them reside within arms, but most are close to arm edges. These <span class="hlt">filaments</span> are comparable in length to the Galactic scale height and therefore are not simply part of a grander turbulent cascade. These giant <span class="hlt">filaments</span>, which often contain regularly spaced pc-scale clumps, are much larger than the <span class="hlt">filaments</span> found in the Herschel Gould's Belt Survey, and they form the upper ends in the filamentary hierarchy. Full operational ALMA and NOEMA will be able to resolve and characterize similar <span class="hlt">filaments</span> in nearby spiral galaxies, allowing us to compare the star formation in a uniform context of spiral arms.</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://adsabs.harvard.edu/abs/2018PlST...20f5101Q','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018PlST...20f5101Q"><span>Combined Langmuir-magnetic probe measurements of type-I ELMy <span class="hlt">filaments</span> in the EAST tokamak</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Qingquan, YANG; Fangchuan, ZHONG; Guosheng, XU; Ning, YAN; Liang, CHEN; Xiang, LIU; Yong, LIU; Liang, WANG; Zhendong, YANG; Yifeng, WANG; Yang, YE; Heng, ZHANG; Xiaoliang, Li</p> <p>2018-06-01</p> <p>Detailed investigations on the filamentary structures associated with the type-I edge-localized modes (ELMs) should be helpful for protecting the materials of a plasma-facing wall on a future large device. Related experiments have been carefully conducted in the Experimental Advanced Superconducting Tokamak (EAST) using combined Langmuir-magnetic probes. The experimental results indicate that the radially outward velocity of type-I ELMy <span class="hlt">filaments</span> can be up to 1.7 km s‑1 in the far scrape-off layer (SOL) region. It is remarkable that the electron temperature of these <span class="hlt">filaments</span> is detected to be ∼50 eV, corresponding to a fraction of 1/6 to the temperature near the pedestal top, while the density (∼ 3× {10}19 {{{m}}}-3) of these <span class="hlt">filaments</span> could be approximate to the line-averaged density. In addition, associated magnetic fluctuations have been clearly observed at the same time, which show good agreement with the density perturbations. A localized <span class="hlt">current</span> on the order of ∼100 kA could be estimated within the <span class="hlt">filaments</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-GSFC_20171208_Archive_e001051.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-GSFC_20171208_Archive_e001051.html"><span>Hanging <span class="hlt">Filament</span></span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2014-06-16</p> <p>The Sun sported a very long <span class="hlt">filament</span> that stretched out over 500,000 miles (800,000 km) and was visible for several days (June 3-4, 2014). It broke apart and dissipated soon after the end of the video clip. <span class="hlt">Filaments</span> are tenuous strands of plasma held above the Sun's surface by magnetic forces. They appear darker because their temperature is somewhat cooler than that of the Sun's surface. The still image, shown in a combination of two wavelengths of extreme ultraviolet light, was taken at 11:33 UT on June 4. Credit: NASA/Goddard/Solar Dynamics Observatory NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27337469','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27337469"><span><span class="hlt">Filamentous</span> Fungi.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Powers-Fletcher, Margaret V; Kendall, Brian A; Griffin, Allen T; Hanson, Kimberly E</p> <p>2016-06-01</p> <p><span class="hlt">Filamentous</span> mycoses are often associated with significant morbidity and mortality. Prompt diagnosis and aggressive treatment are essential for good clinical outcomes in immunocompromised patients. The host immune response plays an essential role in determining the course of exposure to potential fungal pathogens. Depending on the effectiveness of immune response and the burden of organism exposure, fungi can either be cleared or infection can occur and progress to a potentially fatal invasive disease. Nonspecific cellular immunity (i.e., neutrophils, natural killer [NK] cells, and macrophages) combined with T-cell responses are the main immunologic mechanisms of protection. The most common potential mold pathogens include certain hyaline hyphomycetes, endemic fungi, the Mucorales, and some dematiaceous fungi. Laboratory diagnostics aimed at detecting and differentiating these organisms are crucial to helping clinicians make informed decisions about treatment. The purpose of this chapter is to provide an overview of the medically important fungal pathogens, as well as to discuss the patient characteristics, antifungal-therapy considerations, and laboratory tests used in <span class="hlt">current</span> clinical practice for the immunocompromised host.</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 tail <span class="hlt">current</span> <span class="hlt">sheet</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4446331','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4446331"><span>Geometrical and Mechanical Properties Control Actin <span class="hlt">Filament</span> Organization</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Ennomani, Hajer; Théry, Manuel; Nedelec, Francois; Blanchoin, Laurent</p> <p>2015-01-01</p> <p>The different actin structures governing eukaryotic cell shape and movement are not only determined by the properties of the actin <span class="hlt">filaments</span> and associated proteins, but also by geometrical constraints. We recently demonstrated that limiting nucleation to specific regions was sufficient to obtain actin networks with different organization. To further investigate how spatially constrained actin nucleation determines the emergent actin organization, we performed detailed simulations of the actin <span class="hlt">filament</span> system using Cytosim. We first calibrated the steric interaction between <span class="hlt">filaments</span>, by matching, in simulations and experiments, the bundled actin organization observed with a rectangular bar of nucleating factor. We then studied the overall organization of actin <span class="hlt">filaments</span> generated by more complex pattern geometries used experimentally. We found that the fraction of parallel versus antiparallel bundles is determined by the mechanical properties of actin <span class="hlt">filament</span> or bundles and the efficiency of nucleation. Thus nucleation geometry, actin <span class="hlt">filaments</span> local interactions, bundle rigidity, and nucleation efficiency are the key parameters controlling the emergent actin architecture. We finally simulated more complex nucleation patterns and performed the corresponding experiments to confirm the predictive capabilities of the model. PMID:26016478</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27977753','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27977753"><span>Recruitment Kinetics of Tropomyosin Tpm3.1 to Actin <span class="hlt">Filament</span> Bundles in the Cytoskeleton Is Independent of Actin <span class="hlt">Filament</span> Kinetics.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Appaduray, Mark A; Masedunskas, Andrius; Bryce, Nicole S; Lucas, Christine A; Warren, Sean C; Timpson, Paul; Stear, Jeffrey H; Gunning, Peter W; Hardeman, Edna C</p> <p>2016-01-01</p> <p>The actin cytoskeleton is a dynamic network of <span class="hlt">filaments</span> that is involved in virtually every cellular process. Most actin <span class="hlt">filaments</span> in metazoa exist as a co-polymer of actin and tropomyosin (Tpm) and the function of an actin <span class="hlt">filament</span> is primarily defined by the specific Tpm isoform associated with it. However, there is little information on the interdependence of these co-polymers during <span class="hlt">filament</span> assembly and disassembly. We addressed this by investigating the recovery kinetics of fluorescently tagged isoform Tpm3.1 into actin <span class="hlt">filament</span> bundles using FRAP analysis in cell culture and in vivo in rats using intracellular intravital microscopy, in the presence or absence of the actin-targeting drug jasplakinolide. The mobile fraction of Tpm3.1 is between 50% and 70% depending on whether the tag is at the C- or N-terminus and whether the analysis is in vivo or in cultured cells. We find that the continuous dynamic exchange of Tpm3.1 is not significantly impacted by jasplakinolide, unlike tagged actin. We conclude that tagged Tpm3.1 may be able to undergo exchange in actin <span class="hlt">filament</span> bundles largely independent of the assembly and turnover of actin.</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('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> <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.ncbi.nlm.nih.gov/pubmed/18179274','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18179274"><span>Mechanical model for <span class="hlt">filament</span> buckling and growth by phase ordering.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Rey, Alejandro D; Abukhdeir, Nasser M</p> <p>2008-02-05</p> <p>A mechanical model of open <span class="hlt">filament</span> shape and growth driven by phase ordering is formulated. For a given phase-ordering driving force, the model output is the <span class="hlt">filament</span> shape evolution and the <span class="hlt">filament</span> end-point kinematics. The linearized model for the slope of the <span class="hlt">filament</span> is the Cahn-Hilliard model of spinodal decomposition, where the buckling corresponds to concentration fluctuations. Two modes are predicted: (i) sequential growth and buckling and (ii) simultaneous buckling and growth. The relation among the maximum buckling rate, <span class="hlt">filament</span> tension, and matrix viscosity is given. These results contribute to ongoing work in smectic A <span class="hlt">filament</span> buckling.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1990DSRA...37.1753S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1990DSRA...37.1753S"><span>A cool upwelling <span class="hlt">filament</span> off Namibia, southwest Africa: preliminary measurements of physical and biological features</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Shillington, F. A.; Peterson, W. T.; Hutchings, L.; Probyn, T. A.; Waldron, H. N.; Agenbag, J. J.</p> <p>1990-11-01</p> <p>Mesoscale physical and biological measurements were made in a cool upwelling <span class="hlt">filament</span> in the Benguela <span class="hlt">Current</span> system, off Namibia in February 1988. The <span class="hlt">filament</span> had been visible on a satellite infra-red image 2 weeks prior to the survey, and was found to be in a decaying state. Temperature, salinity, 0-50 m integratred nitrate, ammonium, oxygen and plankton data have enabled a consistent picture of the structure to be formed, involving four different water bodies. These are (1) typical continental shelf upwelled water inside the shelf break, (2) <span class="hlt">filament</span> water characterized by salinity of 35.2, high surface integrated nitrate, small phytoplankton cells, and large numbers of salps, (3) warm, blue oligotrophic water to the north, and (4) a warm, high salinity anticyclonic eddy to the south. It is suggested that this southern eddy may have originated from the Agulhas <span class="hlt">Current</span> near Cape Town. Anomalously low nitrate concentrations, that could not be explained, were found in a 100 m thick layer between 100 and 200 m depth on the southern edge of the structure.</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('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2289167','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2289167"><span>Kinetic analysis of F-actin depolymerization in polymorphonuclear leukocyte lysates indicates that chemoattractant stimulation increases actin <span class="hlt">filament</span> number without altering the <span class="hlt">filament</span> length distribution</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>1991-01-01</p> <p>The rate of <span class="hlt">filamentous</span> actin (F-actin) depolymerization is proportional to the number of <span class="hlt">filaments</span> depolarizing and changes in the rate are proportional to changes in <span class="hlt">filament</span> number. To determine the number and length of actin <span class="hlt">filaments</span> in polymorphonuclear leukocytes and the change in <span class="hlt">filament</span> number and length that occurs during the increase in F-actin upon chemoattractant stimulation, the time course of cellular F-actin depolymerization in lysates of control and peptide- stimulated cells was examined. F-actin was quantified by the TRITC- labeled phalloidin staining of pelletable actin. Lysis in 1.2 M KCl and 10 microM DNase I minimized the effects of F-actin binding proteins and G-actin, respectively, on the kinetics of depolymerization. To determine <span class="hlt">filament</span> number and length from a depolymerization time course, depolymerization kinetics must be limited by the actin monomer dissociation rate. Comparison of time courses of depolymerization in the presence (pointed ends free) or absence (barbed and pointed ends free) of cytochalasin suggested depolymerization occurred from both ends of the <span class="hlt">filament</span> and that monomer dissociation was rate limiting. Control cells had 1.7 +/- 0.4 x 10(5) <span class="hlt">filaments</span> with an average length of 0.29 +/- 0.09 microns. Chemo-attractant stimulation for 90 s at room temperature with 0.02 microM N-formylnorleucylleucylphenylalanine caused a twofold increase in F-actin and about a two-fold increase in the total number of actin <span class="hlt">filaments</span> to 4.0 +/- 0.5 x 10(5) <span class="hlt">filaments</span> with an average length of 0.27 +/- 0.07 microns. In both cases, most (approximately 80%) of the <span class="hlt">filaments</span> were quite short (less than or equal to 0.18 micron). The length distributions of actin <span class="hlt">filaments</span> in stimulated and control cells were similar. PMID:1918158</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018SCPMA..61f9611L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018SCPMA..61f9611L"><span>Disintegration of an eruptive <span class="hlt">filament</span> via interactions with quasi-separatrix layers</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Liu, Rui; Chen, Jun; Wang, YuMing</p> <p>2018-06-01</p> <p>The disintegration of solar <span class="hlt">filaments</span> via mass drainage is a frequently observed phenomenon during a variety of <span class="hlt">filament</span> activities. It is generally considered that the draining of dense <span class="hlt">filament</span> material is directed by both gravity and magnetic field, yet the detailed process remains elusive. Here we report on a partial <span class="hlt">filament</span> eruption during which <span class="hlt">filament</span> material drains downward to the surface not only along the <span class="hlt">filament</span>'s legs, but to a remote flare ribbon through a fan-out curtain-like structure. It is found that the magnetic configuration is characterized by two conjoining dome-like quasi-sepratrix layers (QSLs). The <span class="hlt">filament</span> is located underneath one QSL dome, whose footprint apparently bounds the major flare ribbons resulting from the <span class="hlt">filament</span> eruption, whereas the remote flare ribbon matches well with the other QSL dome's far-side footprint. We suggest that the interaction of the <span class="hlt">filament</span> with the overlying QSLs results in the splitting and disintegration of the <span class="hlt">filament</span>.</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> </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=19930000416&hterms=prepregs&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dprepregs','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19930000416&hterms=prepregs&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dprepregs"><span>System Applies Polymer Powder To <span class="hlt">Filament</span> Tow</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Baucom, Robert M.; Snoha, John J.; Marchello, Joseph M.</p> <p>1993-01-01</p> <p>Polymer powder applied uniformly and in continuous manner. Powder-coating system applies dry polymer powder to continuous fiber tow. Unique <span class="hlt">filament</span>-spreading technique, combined with precise control of tension on fibers in system, ensures uniform application of polymer powder to web of spread <span class="hlt">filaments</span>. Fiber tows impregnated with dry polymer powders ("towpregs") produced for preform-weaving and composite-material-molding applications. System and process valuable to prepreg industry, for production of flexible <span class="hlt">filament</span>-windable tows and high-temperature polymer prepregs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4995035','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4995035"><span>A Robust Actin <span class="hlt">Filaments</span> Image Analysis Framework</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Alioscha-Perez, Mitchel; Benadiba, Carine; Goossens, Katty; Kasas, Sandor; Dietler, Giovanni; Willaert, Ronnie; Sahli, Hichem</p> <p>2016-01-01</p> <p>The cytoskeleton is a highly dynamical protein network that plays a central role in numerous cellular physiological processes, and is traditionally divided into three components according to its chemical composition, i.e. actin, tubulin and intermediate <span class="hlt">filament</span> cytoskeletons. Understanding the cytoskeleton dynamics is of prime importance to unveil mechanisms involved in cell adaptation to any stress type. Fluorescence imaging of cytoskeleton structures allows analyzing the impact of mechanical stimulation in the cytoskeleton, but it also imposes additional challenges in the image processing stage, such as the presence of imaging-related artifacts and heavy blurring introduced by (high-throughput) automated scans. However, although there exists a considerable number of image-based analytical tools to address the image processing and analysis, most of them are unfit to cope with the aforementioned challenges. <span class="hlt">Filamentous</span> structures in images can be considered as a piecewise composition of quasi-straight segments (at least in some finer or coarser scale). Based on this observation, we propose a three-steps actin <span class="hlt">filaments</span> extraction methodology: (i) first the input image is decomposed into a ‘cartoon’ part corresponding to the <span class="hlt">filament</span> structures in the image, and a noise/texture part, (ii) on the ‘cartoon’ image, we apply a multi-scale line detector coupled with a (iii) quasi-straight <span class="hlt">filaments</span> merging algorithm for fiber extraction. The proposed robust actin <span class="hlt">filaments</span> image analysis framework allows extracting individual <span class="hlt">filaments</span> in the presence of noise, artifacts and heavy blurring. Moreover, it provides numerous parameters such as <span class="hlt">filaments</span> orientation, position and length, useful for further analysis. Cell image decomposition is relatively under-exploited in biological images processing, and our study shows the benefits it provides when addressing such tasks. Experimental validation was conducted using publicly available datasets, and in osteoblasts</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/11015144','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/11015144"><span>Safety assessment of continuous glass <span class="hlt">filaments</span> used in eclipse.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Swauger, J E; Foy, J W</p> <p>2000-11-01</p> <p>Eclipse is a cigarette that produces smoke by primarily heating, rather than burning, tobacco. The Eclipse heat source assembly employs a continuous <span class="hlt">filament</span> glass mat jacket to insulate the heat source. The glass mat insulator is composed of continuous glass <span class="hlt">filaments</span> and a binder. The purpose of this article is to address the potential toxicological significance of the continuous glass <span class="hlt">filaments</span> under the conditions of intended use. Transfer data and the unique physical characteristics of the <span class="hlt">filaments</span> demonstrate that significant exposure of the smoker will not occur. The available environmental survey data clearly demonstrate that Eclipse smokers are extremely unlikely to be exposed to continuous glass <span class="hlt">filaments</span> at a level that represents a biologically significant increase over background exposure to glass fibers. The chemical composition of the continuous glass <span class="hlt">filaments</span> used in Eclipse is generally similar to C-glass fiber compositions such as MMVF 11 that have failed to produce either tumors or fibrosis in chronic inhalation studies conducted in rats. In vitro dissolution data demonstrate that the continuous glass <span class="hlt">filaments</span> used in Eclipse are more soluble than biologically active fibers such as rock wool (MMVF 21) or asbestos. However, the continuous glass <span class="hlt">filaments</span> used in Eclipse were not as soluble in simulated extracellular lung fluid as representative C-glass fibers (MMVF 10 and MMVF 11). In brief, exposure of Eclipse smokers to continuous glass <span class="hlt">filaments</span> is extremely unlikely to occur at a level that may be construed to be of biological significance.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018LaPhL..15g5403P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018LaPhL..15g5403P"><span>Two-dimensional photoacoustic imaging of femtosecond <span class="hlt">filament</span> in water</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Potemkin, F. V.; Mareev, E. I.; Rumiantsev, B. V.; Bychkov, A. S.; Karabutov, A. A.; Cherepetskaya, E. B.; Makarov, V. A.</p> <p>2018-07-01</p> <p>We report a first-of-its-kind optoacoustic tomography of a femtosecond <span class="hlt">filament</span> in water. Using a broadband (~100 MHz) piezoelectric transducer and a back-projection reconstruction technique, a single <span class="hlt">filament</span> profile was retrieved. Obtained pressure distribution induced by the femtosecond <span class="hlt">filament</span> allowed us to identify the size of the core and the energy reservoir with spatial resolution better than 10 µm. The photoacoustic imaging provides direct measurements of the energy deposition into the medium under <span class="hlt">filamentation</span> of ultrashort laser pulses that cannot be obtained by existing techniques. In combination with a relative simplicity and high accuracy, photoacoustic imaging can be considered as a breakthrough instrument for <span class="hlt">filamentation</span> investigation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=396964','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=396964"><span>Thioredoxin is required for <span class="hlt">filamentous</span> phage assembly.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Russel, M; Model, P</p> <p>1985-01-01</p> <p>Sequence comparisons show that the fip gene product of Escherichia coli, which is required for <span class="hlt">filamentous</span> phage assembly, is thioredoxin. Thioredoxin serves as a cofactor for reductive processes in many cell types and is a constituent of phage T7 DNA polymerase. The fip-1 mutation makes <span class="hlt">filamentous</span> phage and T7 growth temperature sensitive in cells that carry it. The lesion lies within a highly conserved thioredoxin active site. Thioredoxin reductase (NADPH), as well as thioredoxin, is required for efficient <span class="hlt">filamentous</span> phage production. Mutant phages defective in phage gene I are particularly sensitive to perturbations in the fip-thioredoxin system. A speculative model is presented in which thioredoxin reductase, thioredoxin, and the gene I protein interact to drive an engine for <span class="hlt">filamentous</span> phage assembly. Images PMID:3881756</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22370238-simultaneous-transverse-oscillations-prominence-filament-longitudinal-oscillation-another-filament-induced-single-shock-wave','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22370238-simultaneous-transverse-oscillations-prominence-filament-longitudinal-oscillation-another-filament-induced-single-shock-wave"><span>Simultaneous transverse oscillations of a prominence and a <span class="hlt">filament</span> and longitudinal oscillation of another <span class="hlt">filament</span> induced by a single shock wave</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>Shen, Yuandeng; Liu, Ying D.; Chen, P. F.</p> <p>2014-11-10</p> <p>We present the first stereoscopic and Doppler observations of simultaneous transverse oscillations of a prominence and a <span class="hlt">filament</span> and longitudinal oscillation of another <span class="hlt">filament</span> launched by a single shock wave. Using Hα Doppler observations, we derive the three-dimensional oscillation velocities at different heights along the prominence axis. The results indicate that the prominence has a larger oscillation amplitude and damping time at higher altitude, but the periods at different heights are the same (i.e., 13.5 minutes). This suggests that the prominence oscillates like a linear vertical rigid body with one end anchored on the Sun. One of the <span class="hlt">filaments</span> showsmore » weak transverse oscillation after the passing of the shock, which is possibly due to the low altitude of the <span class="hlt">filament</span> and the weakening (due to reflection) of the shock wave before the interaction. Large-amplitude longitudinal oscillation is observed in the other <span class="hlt">filament</span> after the passing of the shock wave. The velocity amplitude and period are about 26.8 km s{sup –1} and 80.3 minutes, respectively. We propose that the orientation of a <span class="hlt">filament</span> or prominence relative to the normal vector of the incoming shock should be an important factor for launching transverse or longitudinal <span class="hlt">filament</span> oscillations. In addition, the restoring forces of the transverse prominence are most likely due to the coupling of gravity and magnetic tension of the supporting magnetic field, while that for the longitudinal <span class="hlt">filament</span> oscillation is probably the resultant force of gravity and magnetic pressure.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28114270','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28114270"><span>Long-range self-organization of cytoskeletal myosin II <span class="hlt">filament</span> stacks.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hu, Shiqiong; Dasbiswas, Kinjal; Guo, Zhenhuan; Tee, Yee-Han; Thiagarajan, Visalatchi; Hersen, Pascal; Chew, Teng-Leong; Safran, Samuel A; Zaidel-Bar, Ronen; Bershadsky, Alexander D</p> <p>2017-02-01</p> <p>Although myosin II <span class="hlt">filaments</span> are known to exist in non-muscle cells, their dynamics and organization are incompletely understood. Here, we combined structured illumination microscopy with pharmacological and genetic perturbations, to study the process of actomyosin cytoskeleton self-organization into arcs and stress fibres. A striking feature of the myosin II <span class="hlt">filament</span> organization was their 'registered' alignment into stacks, spanning up to several micrometres in the direction orthogonal to the parallel actin bundles. While turnover of individual myosin II <span class="hlt">filaments</span> was fast (characteristic half-life time 60 s) and independent of actin <span class="hlt">filament</span> turnover, the process of stack formation lasted a longer time (in the range of several minutes) and required myosin II contractility, as well as actin <span class="hlt">filament</span> assembly/disassembly and crosslinking (dependent on formin Fmnl3, cofilin1 and α-actinin-4). Furthermore, myosin <span class="hlt">filament</span> stack formation involved long-range movements of individual myosin <span class="hlt">filaments</span> towards each other suggesting the existence of attractive forces between myosin II <span class="hlt">filaments</span>. These forces, possibly transmitted via mechanical deformations of the intervening actin <span class="hlt">filament</span> network, may in turn remodel the actomyosin cytoskeleton and drive its self-organization.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017sfcc.confE..57T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017sfcc.confE..57T"><span><span class="hlt">Filaments</span> in Lupus I</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Takahashi, Satoko; Rodon, J.; De Gregorio-Monsalvo, I.; Plunkett, A.</p> <p>2017-06-01</p> <p>The mechanisms behind the formation of sub-stellar mass sources are key to determine the populations at the low-mass end of the stellar distribution. Here, we present mapping observations toward the Lupus I cloud in C18O(2-1) and 13CO(2-1) obtained with APEX. We have identified a few velocity-coherent <span class="hlt">filaments</span>. Each contains several substellar mass sources that are also identified in the 1.1mm continuum data (see also SOLA catalogue presentation). We will discuss the velocity structure, fragmentation properties of the identified <span class="hlt">filaments</span>, and the nature of the detected sources.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014APS..DPPGI1006H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014APS..DPPGI1006H"><span>The influence of <span class="hlt">Filaments</span> in the Private Flux Region on Divertor Power and Particle Deposition</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Harrison, James</p> <p>2014-10-01</p> <p>Recent advances in imaging of the MAST divertor have revealed, for the first time, evidence for <span class="hlt">filaments</span> in the private flux region (PFR). Detailed analysis of the image data shows 3 distinct types of fluctuations occurring within the divertor volume: highly sheared <span class="hlt">filaments</span> in the SOL originating from the outer midplane, high frequency (>50 kHz) <span class="hlt">filaments</span> near the separatrix of the outer divertor leg and <span class="hlt">filaments</span> in the private flux region originating from inner divertor leg. With the need to extrapolate divertor performance from existing machines to future devices, these observations can contribute to our quantitative understanding of transport in the PFR. In particular, they suggest that transport in the PFR is, at least in part, driven by turbulence, which may not be well captured by the Eich/Wagner description of the divertor footprint, expressed in terms of exponential decay in space above the X-point and Gaussian spreading below the X-point. The PFR <span class="hlt">filaments</span> are observed to move largely parallel with the flux surfaces in a way equivalent to a toroidal angular velocity of order 2 ×104 rad/s in H-mode, and slower by a factor of order 2 in L-mode. During their transit parallel to the flux surfaces across the PFR, the <span class="hlt">filaments</span> eject plasma in bursts, away from the separatrix, deeper into the private flux region. Correlation analysis suggests that they are generated by processes local to the inner divertor leg, as there is a weak correlation between fluctuations in the SOL and PFR above what is expected from line integration effects. Scaling of <span class="hlt">filament</span> properties with machine operating parameters, such as plasma <span class="hlt">current</span>, density and auxiliary heating power will be presented, together with a comparison with data from divertor Langmuir probes and IR thermography to estimate the role PFR <span class="hlt">filaments</span> play in determining the width of the divertor footprint.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007AAS...210.5302M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007AAS...210.5302M"><span>Observations of the Merging of Two Quiescent <span class="hlt">Filaments</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mikurda, Katarzyna; Martin, S. F.</p> <p>2007-05-01</p> <p>The two <span class="hlt">filaments</span> were observed close to disk center in the same field of view of approximately 9x9 arc. min. The observations were made using a tunable lithium niobate, narrow band etalon on the 25 cm Martin Solar Telescope at Helio Research in southern California. One <span class="hlt">filament</span> was close to the equator and was oriented nearly east-west and the other, to the west, was oriented north-south with the north end approximately 120 Mm from the west end of the equatorial <span class="hlt">filament</span>. Continued observations were made of these <span class="hlt">filaments</span> for 2 to 5.5 hours per day between October 10 and 15, 2004. The observations were made at multiple wavelengths within + and - 1 Å around Hα. We compared Hα centerline images with data taken by SOHO/EIT at 304A and observed significant differences in the evolution of the <span class="hlt">filaments</span> at these wavelengths. For example, in EIT 304 Å images the two <span class="hlt">filaments</span> seem to join on October 12, i.e. about two days earlier than in Hα. Moreover, the observed merging took longer (over three days) in Hα than in EIT 304 Å images, where it took place on a single day. The dynamics of the merger event is demonstrated with Hα and EIT 304 Å movies. The Doppler velocities calculated from the line wings images before, during and after the merging event were in the normal range for quiescent <span class="hlt">filaments</span>. In our investigation of subsequent SOHO/EIT images at 304 Å we found no sign of an eruption due to the merging of the <span class="hlt">filaments</span>. The contribution of KM was supported under NASA grant NAG5-10852 and SFM acknowledges NSF grant ATM-0519249.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1999APS..DFD..DK05W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1999APS..DFD..DK05W"><span>Dynamics and Breakup of a Contracting Viscous <span class="hlt">Filament</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wilkes, Edward; Notz, Patrick; Ambravaneswaran, Bala; Basaran, Osman</p> <p>1999-11-01</p> <p>Free viscous <span class="hlt">filaments</span> are formed during the breakup of liquid drops and jets. Such <span class="hlt">filaments</span> are typically precursors of satellite droplets that are often undesirable in applications such as ink-jet printing. In this paper, the contraction of an axisymmetric liquid <span class="hlt">filament</span> due to action of surface tension is studied theoretically. The analysis is based on solving (a) the full Navier-Stokes system in two-dimensions (2-d) and (b) a one-dimensional (1-d) approximation of the exact equations based on slender-jet theory. The rigorous, 2-d calculations are carried out with finite element algorithms using either algebraic or elliptic mesh generation. As the <span class="hlt">filament</span> contracts, bulbous regions form at its two ends. When the initial aspect ratio a/b and/or the Reynolds number Re are sufficiently low, the ends coalesce into an oscillating free drop. <span class="hlt">Filament</span> breakup occurs when a/b and/or Re are sufficiently high. The 2-d algorithms reveal for the first time that liquid <span class="hlt">filaments</span> of finite viscosity can overturn prior to interface rupture. The power of elliptic mesh generation over algebraic methods in analyzing such situations is highlighted.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/1141376','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/1141376"><span>Oriented thick and thin <span class="hlt">filaments</span> in Amoeba proteus.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Rinaldi, R A; Hrebenda, B</p> <p>1975-07-01</p> <p>Actin and myosin <span class="hlt">filaments</span> as a foundation of contractile systems are well established from ameba to man (3). Wolpert et al. (19) isolated by differential centrifugation from Amoeba proteus a motile fraction composed of <span class="hlt">filaments</span> which moved upon the addition of ATP. Actin <span class="hlt">filaments</span> are found in amebas (1, 12, 13) which react with vertebrate heavy meromyosin (HMM), forming arrowhead complexes as vertebrate actin (3, 9), and are prominent within the ectoplasmic tube where some of them are attached to the plasmalemma (1, 12). Thick and thin <span class="hlt">filaments</span> possessing the morphological characteristics of myosin and actin have been obtained from isolated ameba cytoplasm (18, 19). In addition, there are <span class="hlt">filaments</span> exhibiting ATPase activity in amebas which react with actin (12, 16, 17). However, giant ameba (Chaos-proteus) shapes are difficult to preserve, and the excellent contributions referred to above are limited by visible distortions occurring in the amebas (rounding up, pseudopods disappearing, and cellular organelles swelling) upon fixation. Achievement of normal ameboid shape in recent glycerination work (15) led us to attempt other electron microscope fixation techniques, resulting in a surprising preservation of A. proteus with a unique orientation of thick and thin <span class="hlt">filaments</span> in the ectoplasmic region.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018MNRAS.474.4881H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018MNRAS.474.4881H"><span>Accretion-driven turbulence in <span class="hlt">filaments</span> - I. Non-gravitational accretion</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Heigl, S.; Burkert, A.; Gritschneder, M.</p> <p>2018-03-01</p> <p>We study accretion-driven turbulence for different inflow velocities in star-forming <span class="hlt">filaments</span> using the code RAMSES. <span class="hlt">Filaments</span> are rarely isolated objects and their gravitational potential will lead to radially dominated accretion. In the non-gravitational case, accretion by itself can already provoke non-isotropic, radially dominated turbulent motions responsible for the complex structure and non-thermal line widths observed in <span class="hlt">filaments</span>. We find that there is a direct linear relation between the absolute value of the total density-weighted velocity dispersion and the infall velocity. The turbulent velocity dispersion in the <span class="hlt">filaments</span> is independent of sound speed or any net flow along the <span class="hlt">filament</span>. We show that the density-weighted velocity dispersion acts as an additional pressure term, supporting the <span class="hlt">filament</span> in hydrostatic equilibrium. Comparing to observations, we find that the projected non-thermal line width variation is generally subsonic independent of inflow velocity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015MNRAS.450.4043W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015MNRAS.450.4043W"><span>Large-scale <span class="hlt">filaments</span> associated with Milky Way spiral arms</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, Ke; Testi, Leonardo; Ginsburg, Adam; Walmsley, C. Malcolm; Molinari, Sergio; Schisano, Eugenio</p> <p>2015-07-01</p> <p>The ubiquity of filamentary structure at various scales throughout the Galaxy has triggered a renewed interest in their formation, evolution, and role in star formation. The largest <span class="hlt">filaments</span> can reach up to Galactic scale as part of the spiral arm structure. However, such large-scale <span class="hlt">filaments</span> are hard to identify systematically due to limitations in identifying methodology (i.e. as extinction features). We present a new approach to directly search for the largest, coldest, and densest <span class="hlt">filaments</span> in the Galaxy, making use of sensitive Herschel Hi-GAL (Herschel Infrared Galactic Plane Survey) data complemented by spectral line cubes. We present a sample of the nine most prominent Herschel <span class="hlt">filaments</span>, including six identified from a pilot search field plus three from outside the field. These <span class="hlt">filaments</span> measure 37-99 pc long and 0.6-3.0 pc wide with masses (0.5-8.3) × 104 M⊙, and beam-averaged (28 arcsec, or 0.4-0.7 pc) peak H2 column densities of (1.7-9.3)× 1022 cm- 2. The bulk of the <span class="hlt">filaments</span> are relatively cold (17-21 K), while some local clumps have a dust temperature up to 25-47 K. All the <span class="hlt">filaments</span> are located within ≲60 pc from the Galactic mid-plane. Comparing the <span class="hlt">filaments</span> to a recent spiral arm model incorporating the latest parallax measurements, we find that 7/9 of them reside within arms, but most are close to arm edges. These <span class="hlt">filaments</span> are comparable in length to the Galactic scaleheight and therefore are not simply part of a grander turbulent cascade.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009IJMSp.279...87J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009IJMSp.279...87J"><span>Isotope ratio measurements of pg-size plutonium samples using TIMS in combination with "multiple ion counting" and <span class="hlt">filament</span> carburization</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jakopic, Rozle; Richter, Stephan; Kühn, Heinz; Benedik, Ljudmila; Pihlar, Boris; Aregbe, Yetunde</p> <p>2009-01-01</p> <p>A sample preparation procedure for isotopic measurements using thermal ionization mass spectrometry (TIMS) was developed which employs the technique of carburization of rhenium <span class="hlt">filaments</span>. Carburized <span class="hlt">filaments</span> were prepared in a special vacuum chamber in which the <span class="hlt">filaments</span> were exposed to benzene vapour as a carbon supply and carburized electrothermally. To find the optimal conditions for the carburization and isotopic measurements using TIMS, the influence of various parameters such as benzene pressure, carburization <span class="hlt">current</span> and the exposure time were tested. As a result, carburization of the <span class="hlt">filaments</span> improved the overall efficiency by one order of magnitude. Additionally, a new "multi-dynamic" measurement technique was developed for Pu isotope ratio measurements using a "multiple ion counting" (MIC) system. This technique was combined with <span class="hlt">filament</span> carburization and applied to the NBL-137 isotopic standard and samples of the NUSIMEP 5 inter-laboratory comparison campaign, which included certified plutonium materials at the ppt-level. The multi-dynamic measurement technique for plutonium, in combination with <span class="hlt">filament</span> carburization, has been shown to significantly improve the precision and accuracy for isotopic analysis of environmental samples with low-levels of plutonium.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://eric.ed.gov/?q=basic+AND+physics&pg=7&id=EJ901516','ERIC'); return false;" href="https://eric.ed.gov/?q=basic+AND+physics&pg=7&id=EJ901516"><span>A First Approach to <span class="hlt">Filament</span> Dynamics</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>Silva, P. E. S.; de Abreu, F. Vistulo; Simoes, R.; Dias, R. G.</p> <p>2010-01-01</p> <p>Modelling elastic <span class="hlt">filament</span> dynamics is a topic of high interest due to the wide range of applications. However, it has reached a high level of complexity in the literature, making it unaccessible to a beginner. In this paper we explain the main steps involved in the computational modelling of the dynamics of an elastic <span class="hlt">filament</span>. We first derive…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19930000325&hterms=lamp&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dlamp','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19930000325&hterms=lamp&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dlamp"><span>Scanning For Hotspots In Lamp <span class="hlt">Filaments</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Powers, Charles E.; Van Sant, Tim; Leidecker, Henning</p> <p>1993-01-01</p> <p>Scanning photometer designed for use in investigation of failures of incandescent lamp <span class="hlt">filaments</span>. Maps brightness as function of position along each <span class="hlt">filament</span> to identify bright (hot) spots, occurring at notches and signifying incipient breaks or rewelds. Also used to measure nonuniformity in outputs of such linear devices as light-emitting diodes, and to measure diffraction patterns of lenses.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22661199-magnetic-fields-massive-dense-cores-dr21-filament-weakly-magnetized-cores-strongly-magnetized-filament','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22661199-magnetic-fields-massive-dense-cores-dr21-filament-weakly-magnetized-cores-strongly-magnetized-filament"><span>Magnetic Fields in the Massive Dense Cores of the DR21 <span class="hlt">Filament</span>: Weakly Magnetized Cores in a Strongly Magnetized <span class="hlt">Filament</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>Ching, Tao-Chung; Lai, Shih-Ping; Zhang, Qizhou</p> <p></p> <p>We present Submillimeter Array 880 μ m dust polarization observations of six massive dense cores in the DR21 <span class="hlt">filament</span>. The dust polarization shows complex magnetic field structures in the massive dense cores with sizes of 0.1 pc, in contrast to the ordered magnetic fields of the parsec-scale <span class="hlt">filament</span>. The major axes of the massive dense cores appear to be aligned either parallel or perpendicular to the magnetic fields of the <span class="hlt">filament</span>, indicating that the parsec-scale magnetic fields play an important role in the formation of the massive dense cores. However, the correlation between the major axes of the cores andmore » the magnetic fields of the cores is less significant, suggesting that during the core formation, the magnetic fields below 0.1 pc scales become less important than the magnetic fields above 0.1 pc scales in supporting a core against gravity. Our analysis of the angular dispersion functions of the observed polarization segments yields a plane-of-sky magnetic field strength of 0.4–1.7 mG for the massive dense cores. We estimate the kinematic, magnetic, and gravitational virial parameters of the <span class="hlt">filament</span> and the cores. The virial parameters show that the gravitational energy in the <span class="hlt">filament</span> dominates magnetic and kinematic energies, while the kinematic energy dominates in the cores. Our work suggests that although magnetic fields may play an important role in a collapsing <span class="hlt">filament</span>, the kinematics arising from gravitational collapse must become more important than magnetic fields during the evolution from <span class="hlt">filaments</span> to massive dense cores.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25788699','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25788699"><span>The evolution of compositionally and functionally distinct actin <span class="hlt">filaments</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Gunning, Peter W; Ghoshdastider, Umesh; Whitaker, Shane; Popp, David; Robinson, Robert C</p> <p>2015-06-01</p> <p>The actin <span class="hlt">filament</span> is astonishingly well conserved across a diverse set of eukaryotic species. It has essentially remained unchanged in the billion years that separate yeast, Arabidopsis and man. In contrast, bacterial actin-like proteins have diverged to the extreme, and many of them are not readily identified from sequence-based homology searches. Here, we present phylogenetic analyses that point to an evolutionary drive to diversify actin <span class="hlt">filament</span> composition across kingdoms. Bacteria use a one-<span class="hlt">filament</span>-one-function system to create distinct <span class="hlt">filament</span> systems within a single cell. In contrast, eukaryotic actin is a universal force provider in a wide range of processes. In plants, there has been an expansion of the number of closely related actin genes, whereas in fungi and metazoa diversification in tropomyosins has increased the compositional variety in actin <span class="hlt">filament</span> systems. Both mechanisms dictate the subset of actin-binding proteins that interact with each <span class="hlt">filament</span> type, leading to specialization in function. In this Hypothesis, we thus propose that different mechanisms were selected in bacteria, plants and metazoa, which achieved actin <span class="hlt">filament</span> compositional variation leading to the expansion of their functional diversity. © 2015. Published by The Company of Biologists Ltd.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=149980','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=149980"><span>Actin <span class="hlt">Filament</span> Polymerization Regulates Gliding Motility by Apicomplexan ParasitesV⃞</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Wetzel, D.M.; Håkansson, S.; Hu, K.; Roos, D.; Sibley, L.D.</p> <p>2003-01-01</p> <p>Host cell entry by Toxoplasma gondii depends critically on actin <span class="hlt">filaments</span> in the parasite, yet paradoxically, its actin is almost exclusively monomeric. In contrast to the absence of stable <span class="hlt">filaments</span> in conventional samples, rapid-freeze electron microscopy revealed that actin <span class="hlt">filaments</span> were formed beneath the plasma membrane of gliding parasites. To investigate the role of actin <span class="hlt">filaments</span> in motility, we treated parasites with the <span class="hlt">filament</span>-stabilizing drug jasplakinolide (JAS) and monitored the distribution of actin in live and fixed cells using yellow fluorescent protein (YFP)-actin. JAS treatment caused YFP-actin to redistribute to the apical and posterior ends, where <span class="hlt">filaments</span> formed a spiral pattern subtending the plasma membrane. Although previous studies have suggested that JAS induces rigor, videomicroscopy demonstrated that JAS treatment increased the rate of parasite gliding by approximately threefold, indicating that <span class="hlt">filaments</span> are rate limiting for motility. However, JAS also frequently reversed the normal direction of motility, disrupting forward migration and cell entry. Consistent with this alteration, subcortical <span class="hlt">filaments</span> in JAS-treated parasites occurred in tangled plaques as opposed to the straight, roughly parallel orientation observed in control cells. These studies reveal that precisely controlled polymerization of actin <span class="hlt">filaments</span> imparts the correct timing, duration, and directionality of gliding motility in the Apicomplexa. PMID:12589042</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.osti.gov/pages/biblio/1235161-plethora-transitions-during-breakup-liquid-filaments','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1235161-plethora-transitions-during-breakup-liquid-filaments"><span>Plethora of transitions during breakup of liquid <span class="hlt">filaments</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Castrejón-Pita, José Rafael; Castrejón-Pita, Alfonso Arturo; Thete, Sumeet Suresh; ...</p> <p>2015-03-30</p> <p>Thinning and breakup of liquid <span class="hlt">filaments</span> are central to dripping of leaky faucets, inkjet drop formation, and raindrop fragmentation. As the <span class="hlt">filament</span> radius decreases, curvature and capillary pressure, both inversely proportional to radius, increase and fluid is expelled with increasing velocity from the neck. As the neck radius vanishes, the governing equations become singular and the <span class="hlt">filament</span> breaks. In slightly viscous liquids, thinning initially occurs in an inertial regime where inertial and capillary forces balance. By contrast, in highly viscous liquids, initial thinning occurs in a viscous regime where viscous and capillary forces balance. As the <span class="hlt">filament</span> thins, viscous forcesmore » in the former case and inertial forces in the latter become important, and theory shows that the <span class="hlt">filament</span> approaches breakup in the final inertial–viscous regime where all three forces balance. However, previous simulations and experiments reveal that transition from an initial to the final regime either occurs at a value of <span class="hlt">filament</span> radius well below that predicted by theory or is not observed. In this paper, we perform new simulations and experiments, and show that a thinning <span class="hlt">filament</span> unexpectedly passes through a number of intermediate transient regimes, thereby delaying onset of the inertial–viscous regime. Finally, the new findings have practical implications regarding formation of undesirable satellite droplets and also raise the question as to whether similar dynamical transitions arise in other free-surface flows such as coalescence that also exhibit singularities.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4403208','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4403208"><span>Plethora of transitions during breakup of liquid <span class="hlt">filaments</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>Castrejón-Pita, José Rafael; Castrejón-Pita, Alfonso Arturo; Thete, Sumeet Suresh; Sambath, Krishnaraj; Hutchings, Ian M.; Hinch, John; Lister, John R.; Basaran, Osman A.</p> <p>2015-01-01</p> <p>Thinning and breakup of liquid <span class="hlt">filaments</span> are central to dripping of leaky faucets, inkjet drop formation, and raindrop fragmentation. As the <span class="hlt">filament</span> radius decreases, curvature and capillary pressure, both inversely proportional to radius, increase and fluid is expelled with increasing velocity from the neck. As the neck radius vanishes, the governing equations become singular and the <span class="hlt">filament</span> breaks. In slightly viscous liquids, thinning initially occurs in an inertial regime where inertial and capillary forces balance. By contrast, in highly viscous liquids, initial thinning occurs in a viscous regime where viscous and capillary forces balance. As the <span class="hlt">filament</span> thins, viscous forces in the former case and inertial forces in the latter become important, and theory shows that the <span class="hlt">filament</span> approaches breakup in the final inertial–viscous regime where all three forces balance. However, previous simulations and experiments reveal that transition from an initial to the final regime either occurs at a value of <span class="hlt">filament</span> radius well below that predicted by theory or is not observed. Here, we perform new simulations and experiments, and show that a thinning <span class="hlt">filament</span> unexpectedly passes through a number of intermediate transient regimes, thereby delaying onset of the inertial–viscous regime. The new findings have practical implications regarding formation of undesirable satellite droplets and also raise the question as to whether similar dynamical transitions arise in other free-surface flows such as coalescence that also exhibit singularities. PMID:25825761</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013NJPh...15c5006W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013NJPh...15c5006W"><span>Mesoscopic model for <span class="hlt">filament</span> orientation in growing actin networks: the role of obstacle geometry</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Weichsel, Julian; Schwarz, Ulrich S.</p> <p>2013-03-01</p> <p>Propulsion by growing actin networks is a universal mechanism used in many different biological systems, ranging from the <span class="hlt">sheet</span>-like lamellipodium of crawling animal cells to the actin comet tails induced by certain bacteria and viruses in order to move within their host cells. Although the core molecular machinery for actin network growth is well preserved in all of these cases, the geometry of the propelled obstacle varies considerably. During recent years, <span class="hlt">filament</span> orientation distribution has emerged as an important observable characterizing the structure and dynamical state of the growing network. Here we derive several continuum equations for the orientation distribution of <span class="hlt">filaments</span> growing behind stiff obstacles of various shapes and validate the predicted steady state orientation patterns by stochastic computer simulations based on discrete <span class="hlt">filaments</span>. We use an ordinary differential equation approach to demonstrate that for flat obstacles of finite size, two fundamentally different orientation patterns peaked at either ±35° or +70°/0°/ - 70° exhibit mutually exclusive stability, in agreement with earlier results for flat obstacles of very large lateral extension. We calculate and validate phase diagrams as a function of model parameters and show how this approach can be extended to obstacles with piecewise straight contours. For curved obstacles, we arrive at a partial differential equation in the continuum limit, which again is in good agreement with the computer simulations. In all cases, we can identify the same two fundamentally different orientation patterns, but only within an appropriate reference frame, which is adjusted to the local orientation of the obstacle contour. Our results suggest that two fundamentally different network architectures compete with each other in growing actin networks, irrespective of obstacle geometry, and clarify how simulated and electron tomography data have to be analyzed for non-flat obstacle geometries.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19850039591&hterms=current+situation&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dcurrent%2Bsituation','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19850039591&hterms=current+situation&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dcurrent%2Bsituation"><span>Steady-state <span class="hlt">currents</span> in p-n junction <span class="hlt">filaments</span> or grains in case of large surface recombination velocities at lateral surfaces</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Von Roos, O.; Lindholm, F. A.</p> <p>1985-01-01</p> <p>Recently it has been pointed out that the saturation <span class="hlt">current</span> of a semiconductor <span class="hlt">filament</span> which constitutes part of a p-n junction diverges when the surface recombination velocity at the faces become infinitely large. Here it is pointed out that this is to be expected on physical grounds since, whenever the carrier concentration is kept off equilibrium by an outside agent, and at the same time recombination lifetimes in the bulk or in surface layers tend to zero, concentration gradients tend to infinity. As also previously noted, the situation can be remedied by using realistic (finite) surface recombination velocities in model calculations. However, this procedure leads to mathematical complexities which have been circumvented recently by the introduction of a heuristic approach. It is the aim of this paper to assess the validity of the heuristic approach by means of detailed and exact calculations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19820011292','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19820011292"><span>A vortex-<span class="hlt">filament</span> and core model for wings with edge vortex separation</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Pao, J. L.; Lan, C. E.</p> <p>1982-01-01</p> <p>A vortex <span class="hlt">filament</span>-vortex core method for predicting aerodynamic characteristics of slender wings with edge vortex separation was developed. Semi-empirical but simple methods were used to determine the initial positions of the free <span class="hlt">sheet</span> and vortex core. Comparison with available data indicates that: (1) the present method is generally accurate in predicting the lift and induced drag coefficients but the predicted pitching moment is too positive; (2) the spanwise lifting pressure distributions estimated by the one vortex core solution of the present method are significantly better than the results of Mehrotra's method relative to the pressure peak values for the flat delta; (3) the two vortex core system applied to the double delta and strake wings produce overall aerodynamic characteristics which have good agreement with data except for the pitching moment; and (4) the computer time for the present method is about two thirds of that of Mehrotra's method.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19970011043','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19970011043"><span>Rotor Vortex <span class="hlt">Filaments</span>: Living on the Slipstream's Edge</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Young, Larry A.</p> <p>1997-01-01</p> <p>The purpose of this paper is to gain a better understanding of rotor wake evolution in hover and axial flow by deriving an analytical solution for the time dependent behavior of vortex <span class="hlt">filament</span> circulation and core size. This solution is applicable only for vortex <span class="hlt">filaments</span> in the rotor far-wake. A primarily inviscid vortex/shear layer interaction (where the slipstream boundary is modeled as a shear layer) has been identified in this analytical treatment. This vortex/shear layer interaction results in decreasing, vortex <span class="hlt">filament</span> circulation and core size with time. The inviscid vortex/shear layer interaction is shown, in a first-order treatment, to be of greater magnitude than viscous diffusion effects. The rate of contraction, and ultimate collapse, of the vortex <span class="hlt">filament</span> core is found to be directly proportional to the rotor inflow velocity. This new insight into vortex <span class="hlt">filament</span> decay promises to help reconcile several disparate observations made in the literature and will, hopefully, promote new advances in theoretical modeling of rotor wakes.</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('https://eric.ed.gov/?q=This+AND+year&pg=2&id=EJ1174767','ERIC'); return false;" href="https://eric.ed.gov/?q=This+AND+year&pg=2&id=EJ1174767"><span>In Search of the Dimensions of an Incandescent Light Bulb <span class="hlt">Filament</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>Ladino, Luis A.; Rondón, Hermilda S.</p> <p>2018-01-01</p> <p>The purpose of this paper is to present and discuss an alternative solution to an experimental problem given to high school students in the XXII Ibero-American Physics Olympiad held by Colombia this year. From the measurements of electric <span class="hlt">current</span> and potential difference across a small tungsten <span class="hlt">filament</span> lamp students should find the dimensions of…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17681627','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17681627"><span>Proteomics of <span class="hlt">filamentous</span> fungi.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kim, Yonghyun; Nandakumar, M P; Marten, Mark R</p> <p>2007-09-01</p> <p>Proteomic analysis, defined here as the global assessment of cellular proteins expressed in a particular biological state, is a powerful tool that can provide a systematic understanding of events at the molecular level. Proteomic studies of <span class="hlt">filamentous</span> fungi have only recently begun to appear in the literature, despite the prevalence of these organisms in the biotechnology industry, and their importance as both human and plant pathogens. Here, we review recent publications that have used a proteomic approach to develop a better understanding of <span class="hlt">filamentous</span> fungi, highlighting sample preparation methods and whole-cell cytoplasmic proteomics, as well as subproteomics of cell envelope, mitochondrial and secreted proteins.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1145719-detection-characterization-multi-filament-evolution-during-resistive-switching','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1145719-detection-characterization-multi-filament-evolution-during-resistive-switching"><span>Detection and characterization of multi-<span class="hlt">filament</span> evolution during resistive switching</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Mickel, Patrick R.; Lohn, Andrew J.; Marinella, Matthew J.</p> <p>2014-08-05</p> <p>We present resistive switching data in TaO x memristors displaying signatures of multi-<span class="hlt">filament</span> switching modes, and develop a geometrically defined equivalent circuit to separate the individual resistances and powers dissipated in each <span class="hlt">filament</span>. Using these resolved values, we compare the individual switching curves of each <span class="hlt">filament</span> and demonstrate that the switching data of each <span class="hlt">filament</span> collapse onto a single switching curve determined by the analytical steady-state resistive switching solution for filamentary switching. Analyzing our results in terms of this solution, we determine the switching temperature, heat flow, conductivity, and time evolving areas of each <span class="hlt">filament</span> during resistive switching. Finally, wemore » discuss operational modes which may limit the formation of additional conducting <span class="hlt">filaments</span>, potentially leading to increased device endurance.« less</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.ncbi.nlm.nih.gov/pubmed/25533039','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25533039"><span><span class="hlt">Filamentous</span> bacteria existence in aerobic granular reactors.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Figueroa, M; Val del Río, A; Campos, J L; Méndez, R; Mosquera-Corral, A</p> <p>2015-05-01</p> <p><span class="hlt">Filamentous</span> bacteria are associated to biomass settling problems in wastewater treatment plants. In systems based on aerobic granular biomass they have been proposed to contribute to the initial biomass aggregation process. However, their development on mature aerobic granular systems has not been sufficiently studied. In the present research work, <span class="hlt">filamentous</span> bacteria were studied for the first time after long-term operation (up to 300 days) of aerobic granular systems. Chloroflexi and Sphaerotilus natans have been observed in a reactor fed with synthetic wastewater. These <span class="hlt">filamentous</span> bacteria could only come from the inoculated sludge. Thiothrix and Chloroflexi bacteria were observed in aerobic granular biomass treating wastewater from a fish canning industry. Meganema perideroedes was detected in a reactor treating wastewater from a plant processing marine products. As a conclusion, the source of <span class="hlt">filamentous</span> bacteria in these mature aerobic granular systems fed with industrial effluents was the incoming wastewater.</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=2109510','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2109510"><span>Oriented thick and thin <span class="hlt">filaments</span> in amoeba proteus</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Rinaldi, RA; Hrebenda, B</p> <p>1975-01-01</p> <p>Actin and myosin <span class="hlt">filaments</span> as a foundation of contractile systems are well established from ameba to man (3). Wolpert et al. (19) isolated by differential centrifugation from Amoeba proteus a motile fraction composed of <span class="hlt">filaments</span> which moved upon the addition of ATP. Actin <span class="hlt">filaments</span> are found in amebas (1, 12, 13) which react with vertebrate heavy meromyosin (HMM), forming arrowhead complexes as vertebrate actin (3, 9), and are prominent within the ectoplasmic tube where some of them are attached to the plasmalemma (1, 12). Thick and thin <span class="hlt">filaments</span> possessing the morphological characteristics of myosin and actin have been obtained from isolated ameba cytoplasm (18, 19). In addition, there are <span class="hlt">filaments</span> exhibiting ATPase activity in amebas which react with actin (12, 16, 17). However, giant ameba (Chaos-proteus) shapes are difficult to preserve, and the excellent contributions referred to above are limited by visible distortions occurring in the amebas (rounding up, pseudopods disappearing, and cellular organelles swelling) upon fixation. Achievement of normal ameboid shape in recent glycerination work (15) led us to attempt other electron microscope fixation techniques, resulting in a surprising preservation of A. proteus with a unique orientation of thick and thin <span class="hlt">filaments</span> in the ectoplasmic region. PMID:1141376</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JPhD...48K5401M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JPhD...48K5401M"><span>Model-based analysis of keratin intermediate <span class="hlt">filament</span> assembly</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Martin, Ines; Leitner, Anke; Walther, Paul; Herrmann, Harald; Marti, Othmar</p> <p>2015-09-01</p> <p>The cytoskeleton of epithelial cells consists of three types of <span class="hlt">filament</span> systems: microtubules, actin <span class="hlt">filaments</span> and intermediate <span class="hlt">filaments</span> (IFs). Here, we took a closer look at type I and type II IF proteins, i.e. keratins. They are hallmark constituents of epithelial cells and are responsible for the generation of stiffness, the cellular response to mechanical stimuli and the integrity of entire cell layers. Thereby, keratin networks constitute an important instrument for cells to adapt to their environment. In particular, we applied models to characterize the assembly of keratin K8 and K18 into elongated <span class="hlt">filaments</span> as a means for network formation. For this purpose, we measured the length of in vitro assembled keratin K8/K18 <span class="hlt">filaments</span> by transmission electron microscopy at different time points. We evaluated the experimental data of the longitudinal annealing reaction using two models from polymer chemistry: the Schulz-Zimm model and the condensation polymerization model. In both scenarios one has to make assumptions about the reaction process. We compare how well the models fit the measured data and thus determine which assumptions fit best. Based on mathematical modelling of experimental <span class="hlt">filament</span> assembly data we define basic mechanistic properties of the elongation reaction process.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/16822062','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/16822062"><span>Adaptive virus detection using <span class="hlt">filament</span>-coupled antibodies.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Stone, Gregory P; Lin, Kelvin S; Haselton, Frederick R</p> <p>2006-01-01</p> <p>We recently reported the development of a <span class="hlt">filament</span>-antibody recognition assay (FARA), in which the presence of virions in solution initiates the formation of enzyme-linked immunosorbent assay (ELISA)-like antibody complexes. The unique features of this assay are that processing is achieved by motion of a <span class="hlt">filament</span> and that, in the presence of a virus, antibody-virus complexes are coupled to the <span class="hlt">filament</span> at known locations. In this work, we combine the unique features of this assay with a 638-nm laser-based optical detector to enable adaptive control of virus detection. Integration of on-line fluorescence detection yields approximately a five-fold increase in signal-to-noise ratio (SNR) compared to the fluorescence detection method reported previously. A one-minute incubation with an M13K07 test virus is required to detect 10(10) virionsml, and 40 min was required to detect 10(8) virionsml. In tests of the components of an adaptive strategy, a 30-min virus (3.3 x 10(10) virionsml) incubation time, followed by repositioning the <span class="hlt">filament</span>-captured virus either within the detecting antibody chamber, (20 microg ml) or within the virus chamber, found an increase in signal roughly proportional to the cumulative residence times in these chambers. Furthermore, cumulative fluorescence signals observed for a <span class="hlt">filament</span>-captured virus after repeated positioning of the <span class="hlt">filament</span> within the virus chamber are similar to those observed for a single long incubation time. The unique features of the FARA-like design combined with online optical detection to direct subsequent bioprocessing steps provides new flexibility for developing adaptive molecular recognition assays.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/3378667','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/3378667"><span><span class="hlt">Filamentous</span> actin organization in the unfertilized sea urchin egg cortex.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Henson, J H; Begg, D A</p> <p>1988-06-01</p> <p>We have investigated the organization of <span class="hlt">filamentous</span> actin in the cortex of unfertilized eggs of the sea urchins Strongylocentrotus purpuratus and Lytechinus variegatus. Rhodamine phalloidin and anti-actin immunofluorescent staining of isolated cortices reveal a punctate pattern of fluorescent sources. Comparison of this pattern with SEM images of microvillar morphology and distribution indicates that <span class="hlt">filamentous</span> actin in the cortex is predominantly localized in the microvilli. Thin-section TEM and quick-freeze deep-etch ultrastructure of isolated cortices demonstrates that this microvillar-associated actin is in a novel organizational state composed of very short <span class="hlt">filaments</span> arranged in a tight network and that these <span class="hlt">filament</span> networks form mounds that extend beyond the plane of the plasma membrane. Actin <span class="hlt">filaments</span> within the networks do not exhibit free ends and make end-on attachments with the membrane only within the region of the evaginating microvilli. Myosin S-1 dissociable crosslinks, 2-3 nm in diameter, are observed between network <span class="hlt">filaments</span> and between network <span class="hlt">filaments</span> and the membrane. A second population of long, individual actin <span class="hlt">filaments</span> is observed in close lateral association with the plasma membrane and frequently complexes with the microvillar actin networks. The <span class="hlt">filamentous</span> actin of the unfertilized egg cortex may participate in establishing the mechanical properties of the egg surface and may function in nucleating the assembly of cortical actin following fertilization.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016ApJ...831..123Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016ApJ...831..123Z"><span>Material Supply and Magnetic Configuration of an Active Region <span class="hlt">Filament</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zou, P.; Fang, C.; Chen, P. F.; Yang, K.; Hao, Q.; Cao, Wenda</p> <p>2016-11-01</p> <p>It is important to study the fine structures of solar <span class="hlt">filaments</span> with high-resolution observations, since it can help us understand the magnetic and thermal structures of the <span class="hlt">filaments</span> and their dynamics. In this paper, we study a newly formed <span class="hlt">filament</span> located inside the active region NOAA 11762, which was observed by the 1.6 m New Solar Telescope at Big Bear Solar Observatory from 16:40:19 UT to 17:07:58 UT on 2013 June 5. As revealed by the Hα filtergrams, cool material is seen to be injected into the <span class="hlt">filament</span> spine with a speed of 5-10 km s-1. At the source of the injection, brightenings are identified in the chromosphere, which are accompanied by magnetic cancellation in the photosphere, implying the importance of magnetic reconnection in replenishing the <span class="hlt">filament</span> with plasmas from the lower atmosphere. Counter-streamings are detected near one endpoint of the <span class="hlt">filament</span>, with the plane-of-the-sky speed being 7-9 km s-1 in the Hα red-wing filtergrams and 9-25 km s-1 in the blue-wing filtergrams. The observations are indicative that this active region <span class="hlt">filament</span> is supported by a sheared arcade without magnetic dips, and the counter-streamings are due to unidirectional flows with alternative directions, rather than due to the longitudinal oscillations of <span class="hlt">filament</span> threads as in many other <span class="hlt">filaments</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016APS..DFDG18008C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016APS..DFDG18008C"><span>Dynamics of a single flexible <span class="hlt">filament</span> in a flowing soap film</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chen, Chaonan; Feng, Shunshan; Zhou, Tong</p> <p>2016-11-01</p> <p>The interactions between flexible plates and surrounding fluids like two-dimensional flag-in-wind problems are important physical phenomena. Here we use a spandex <span class="hlt">filament</span> with one end fixed flapping in gravity-driven soap film device which can be regarded as a quasi-two-dimensional flow tunnel. A silk <span class="hlt">filament</span> had been used previously to demonstrate three stable dynamical states: stretched-straight, flapping, and bistable states. The similar phenomena occured for a spandex <span class="hlt">filament</span> while the bifurcation conditions seem to be different compared with a silk <span class="hlt">filament</span>, as the critical <span class="hlt">filament</span> length is longer and critical inflow velocity is higher than that for a silk <span class="hlt">filament</span>. In the experiment, we considered some representative parameters (<span class="hlt">filament</span> length, inflow velocity, and bending stiffness of the <span class="hlt">filament</span>) to study their effects on the stability of the <span class="hlt">filament</span> and its bifurcation conditions. An interface-tracking ALE finite element method was then conducted to reproduce the experiment and investigate more details about effects of these parameters. which are significant to reveal the underlying mechanism of flag-in-wind problem. Corresponding Author. Email:zhoutong@bit.edu.cn.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JGRC..120.4516S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JGRC..120.4516S"><span>The Cape Ghir <span class="hlt">filament</span> system in August 2009 (NW Africa)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sangrà, Pablo; Troupin, Charles; Barreiro-González, Beatriz; Desmond Barton, Eric; Orbi, Abdellatif; Arístegui, Javier</p> <p>2015-06-01</p> <p>In the framework of the Canaries-Iberian marine ecosystem Exchanges (CAIBEX) experiment, an interdisciplinary high-resolution survey was conducted in the NW African region of Cape Ghir (30°38'N) during August 2009. The anatomy of a major <span class="hlt">filament</span> is investigated on scales down to the submesoscale using in situ and remotely sensed data. The <span class="hlt">filament</span> may be viewed as a system composed of three intimately connected structures: a small, shallow, and cold <span class="hlt">filament</span> embedded within a larger, deeper, and cool <span class="hlt">filament</span> and an intrathermocline anticyclonic eddy (ITE). The cold <span class="hlt">filament</span>, which stretches 110 km offshore, is a shallow feature 60 m deep and 25 km wide, identified by minimal surface temperatures and rich in chlorophyll a. This structure comprises two asymmetrical submesoscale (˜18 km) fronts with jets flowing in opposite directions. The cold <span class="hlt">filament</span> is embedded near the equatorward boundary of a much broader region of approximately 120 km width and 150 m depth that forms the cool <span class="hlt">filament</span> and stretches at least 200 km offshore. This cool region, partly resulting from the influence of cold <span class="hlt">filament</span>, is limited by two asymmetrical mesoscale (˜50 km) frontal boundaries. At the ITE, located north of the cold <span class="hlt">filament</span>, we observe evidence of downwelling as indicated by a relatively high concentration of particles extending from the surface to more than 200 m depth. We hypothesize that this ITE may act as a sink of carbon and thus the <span class="hlt">filament</span> system may serve dual roles of offshore carbon export and carbon sink.</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. 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