ECE-imaging of the H-mode pedestal (invited).

PubMed

Tobias, B J; Austin, M E; Boom, J E; Burrell, K H; Classen, I G J; Domier, C W; Luhmann, N C; Nazikian, R; Snyder, P B

2012-10-01

A synthetic diagnostic has been developed that reproduces the highly structured electron cyclotron emission (ECE) spectrum radiated from the edge region of H-mode discharges. The modeled dependence on local perturbations of the equilibrium plasma pressure allows for interpretation of ECE data for diagnosis of local quantities. Forward modeling of the diagnostic response in this region allows for improved mapping of the observed fluctuations to flux surfaces within the plasma, allowing for the poloidal mode number of coherent structures to be resolved. In addition, other spectral features that are dependent on both T(e) and n(e) contain information about pedestal structure and the electron energy distribution of localized phenomena, such as edge filaments arising during edge-localized mode (ELM) activity.

Plasma pressure distribution in the surrounding the Earth plasma ring and its role in the magnetospheric dynamics

NASA Astrophysics Data System (ADS)

Antonova, E. E.; Kirpichev, I. P.; Stepanova, M. V.

2014-08-01

We analyzed the characteristics of the plasma region surrounding the Earth at the geocentric distances between 6 and 15RE using the data of THEMIS mission from April 2007 to September 2012. The obtained averaged distributions of plasma pressure, of pressure anisotropy, and of magnetic field near the equatorial plane showed the presence of a ring-shaped structure surrounding the Earth. It was found that for quiet geomagnetic conditions the plasma pressure is nearly isotropic for all magnetic local times at geocentric distances >6RE. Taking into consideration that the minimal values of the magnetic field at the field lines near noon are shifted from the equatorial plane, we estimate the value of plasma beta parameter in the region of minimal values of the magnetic field using the Tsyganenko-2001 magnetic field model. It was found that the values of plasma beta parameter are of the order of unity for the nightside part of the ring-shaped structure in the equatorial plane and for the region of minimal values of the magnetic field in the dayside, indicating that the ring-shaped structure should play an active role in the magnetic field distortion. Comparison of obtained distribution of plasma pressure at the equatorial plane with the values of plasma pressure at low altitudes, showed that the considerable part of the auroral oval can be mapped into the analyzed plasma ring. The role of the high-beta plasma ring surrounding the Earth for Earth-Sun System disturbances is discussed.

FORWARD MODELING OF STANDING KINK MODES IN CORONAL LOOPS. I. SYNTHETIC VIEWS

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

Yuan, Ding; Doorsselaere, Tom Van, E-mail: DYuan2@uclan.ac.uk

2016-04-15

Kink magnetohydrodynamic (MHD) waves are frequently observed in various magnetic structures of the solar atmosphere. They may contribute significantly to coronal heating and could be used as a tool to diagnose the solar plasma. In this study, we synthesize the Fe ix λ171.073 Å emission of a coronal loop supporting a standing kink MHD mode. The kink MHD wave solution of a plasma cylinder is mapped into a semi-torus structure to simulate a curved coronal loop. We decompose the solution into a quasi-rigid kink motion and a quadrupole term, which dominate the plasma inside and outside of the flux tube, respectively.more » At the loop edges, the line of sight integrates relatively more ambient plasma, and the background emission becomes significant. The plasma motion associated with the quadrupole term causes spectral line broadening and emission suppression. The periodic intensity suppression will modulate the integrated intensity and the effective loop width, which both exhibit oscillatory variations at half of the kink period. The quadrupole term can be directly observed as a pendular motion at the front view.« less

Linear theory of plasma Čerenkov masers

NASA Astrophysics Data System (ADS)

Birau, M.

1996-11-01

A different theoretical model of Čerenkov instability in the linear amplification regime of plasma Čerenkov masers is developed. The model assumes a cold relativistic annular electron beam propagating through a column of cold dense plasma, the two bodies being immersed in an infinite magnetic guiding field inside a perfect cylindrical waveguide. In order to simplify the calculations, a radial rectangular distribution of plasma and beam density is assumed and only azimuthal symmetric modes are under investigation. The model's difference consists of taking into account the whole plasma and beam electromagnetic structures in the interpretation of the Čerenkov instability. This model leads to alternative results such as the possibility of emission at several frequencies. In addition, the electric field is calculated taking into account its radial phase dependence, so that a map of the field in the interaction region can be presented.

Toroidal Alfvén eigenmode triggered by trapped anisotropic energetic particles in a toroidal resistive plasma with free boundary

NASA Astrophysics Data System (ADS)

Yang, S. X.; Hao, G. Z.; Liu, Y. Q.; Wang, Z. X.; Hu, Y. J.; Zhu, J. X.; He, H. D.; Wang, A. K.

2018-04-01

The toroidal Alfvén eigenmode (TAE), excited by trapped energetic particles (EPs), is numerically investigated in a tokamak plasma, using the non-perturbative magnetohydrodynamic-kinetic hybrid formulation based MARS-K code (Liu et al 2008 Phys. Plasmas 15 112503). Compared with the fixed boundary condition at the plasma edge, a free boundary enhances the critical value of the EPs kinetic contribution for driving the TAE. Free boundary also induces finite perturbations at the plasma edge as expected. An anisotropic distribution of EPs, in the particle pitch angle space, strongly enhances the instability and results in a more global mode structure, compared with the isotropic case. The plasma resistivity is also found to play a role in the EPs-destabilized TAE. In particular, the mode stability domain is mapped out, in the 2D parameter space of the plasma resistivity and a quantity defining the width of the particle distribution in pitch angle (for anisotropic distribution). A resonance layer in the poloidal mode structure, with the layer width increasing with the plasma resistivity, appears at the large width of the particle distribution in pitch angle space. A mode conversion, from the modified ideal kink by the EPs kinetic effect to the TAE, is also observed while increasing the birth energy of EPs. Computational results suggest that the TAE mode structure can be modified by certain key plasma parameters, such as the EPs kinetic contribution, the equilibrium pressure, the plasma resistivity, the distribution of EPs, as well as the birth energy of EPs. Such modification of the eigenmode structure can only be obtained following the non-perturbative hybrid approach (Wang et al 2013 Phys. Rev. Lett. 111 145003, Wang et al 2015 Phys. Plasmas 22 022509), as adopted in this study. More importantly, numerical results show that near the marginal stability point, the dominant poloidal harmonics of the TAE overlap with each other, and are localized at the tip positions of the Alfvén continua. This kind of TAE structure in high beta plasma with unstable ideal kink is substantially different from that of the conventional TAE.

Concerted spatial-frequency and polarization-phase filtering of laser images of polycrystalline networks of blood plasma smears

NASA Astrophysics Data System (ADS)

Ushenko, Yu A.

2012-11-01

The complex technique of concerted polarization-phase and spatial-frequency filtering of blood plasma laser images is suggested. The possibility of obtaining the coordinate distributions of phases of linearly and circularly birefringent protein networks of blood plasma separately is presented. The statistical (moments of the first to fourth orders) and scale self-similar (logarithmic dependences of power spectra) structure of phase maps of different types of birefringence of blood plasma of two groups of patients-healthy people (donors) and those suffering from rectal cancer-is investigated. The diagnostically sensitive parameters of a pathological change of the birefringence of blood plasma polycrystalline networks are determined. The effectiveness of this technique for detecting change in birefringence in the smears of other biological fluids in diagnosing the appearance of cholelithiasis (bile), operative differentiation of the acute and gangrenous appendicitis (exudate), and differentiation of inflammatory diseases of joints (synovial fluid) is shown.

Seismo-ionospheric anomalies in ionospheric TEC and plasma density before the 17 July 2006 M7.7 south of Java earthquake

NASA Astrophysics Data System (ADS)

Tao, Dan; Cao, Jinbin; Battiston, Roberto; Li, Liuyuan; Ma, Yuduan; Liu, Wenlong; Zhima, Zeren; Wang, Lanwei; Wray Dunlop, Malcolm

2017-04-01

In this paper, we report significant evidence for preseismic ionospheric anomalies in total electron content (TEC) of the global ionosphere map (GIM) and plasma density appearing on day 2 before the 17 July 2006 M7.7 south of Java earthquake. After distinguishing other anomalies related to the geomagnetic activities, we found a temporal precursor around the epicenter on day 2 before the earthquake (15 July 2006), which agrees well with the spatial variations in latitude-longitude-time (LLT) maps. Meanwhile, the sequences of latitude-time-TEC (LTT) plots reveal that the TECs on epicenter side anomalously decrease and lead to an anomalous asymmetric structure with respect to the magnetic equator in the daytime from day 2 before the earthquake. This anomalous asymmetric structure disappears after the earthquake. To further confirm these anomalies, we studied the plasma data from DEMETER satellite in the earthquake preparation zone (2046.4 km in radius) during the period from day 45 before to day 10 after the earthquake, and also found that the densities of both electron and total ion in the daytime significantly increase on day 2 before the earthquake. Very interestingly, O+ density increases significantly and H+ density decreases, while He+ remains relatively stable. These results indicate that there exists a distinct preseismic signal (preseismic ionospheric anomaly) over the epicenter.

FORWARD MODELING OF STANDING KINK MODES IN CORONAL LOOPS. II. APPLICATIONS

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

Yuan, Ding; Doorsselaere, Tom Van, E-mail: DYuan2@uclan.ac.uk

2016-04-15

Magnetohydrodynamic waves are believed to play a significant role in coronal heating, and could be used for remote diagnostics of solar plasma. Both the heating and diagnostic applications rely on a correct inversion (or backward modeling) of the observables into the thermal and magnetic structures of the plasma. However, due to the limited availability of observables, this is an ill-posed issue. Forward modeling is designed to establish a plausible mapping of plasma structuring into observables. In this study, we set up forward models of standing kink modes in coronal loops and simulate optically thin emissions in the extreme ultraviolet bandpasses,more » and then adjust plasma parameters and viewing angles to match three events of transverse loop oscillations observed by the Solar Dynamics Observatory/Atmospheric Imaging Assembly. We demonstrate that forward models could be effectively used to identify the oscillation overtone and polarization, to reproduce the general profile of oscillation amplitude and phase, and to predict multiple harmonic periodicities in the associated emission intensity and loop width variation.« less

Double Magnetic Reconnection Driven by Kelvin-Helmholtz Vortices

NASA Astrophysics Data System (ADS)

Horton, W., Jr.; Faganello, M.; Califano, F.; Pegoraro, F.

2017-12-01

Simulations and theory for the solar wind driven magnetic reconnection in the flanks of the magnetopause is shown to be intrinsically 3D with the secular growth of couple pairs of reconnection regions off the equatorial plane. We call the process double mid-latitude reconnection and show supporting 3D simulations and theory descripting the secular growth of the magnetic reconnection with the resulting mixing of the solar wind plasma with the magnetosphere plasma. The initial phase develops Kelvin-Helmholtz vortices at low-latitude and, through the propagation of Alfven waves far from the region where the stresses are generated, creates a standard quasi-2D low latitude boundary layer magnetic reconnection but off the equatorial plane and with a weak guide field component. The reconnection exponential growth is followed by a secularly growing nonlinear phase that gradually closes the solar wind field lines on the Earth. The nonlinear field line structure provides a channel for penetration of the SW plasma into the MS as observed by spacecraft [THEMIS and Cluster]. The simulations show the amount of solar wind plasma brought into the magnetosphere by tracing the time evolution of the areas corresponding to double reconnected field lines with Poincare maps. The results for the solar wind plasma brought into the magnetosphere seems consistent with the observed plasma transport. Finally, we have shown how the intrinsic 3D nature of the doubly reconnected magnetic field lines leads to the generation of twisted magnetic spatial structures that differ from the quasi-2D magnetic islands structures.

Structure and dynamics of the umagnetized plasma around comet 67P/CG

NASA Astrophysics Data System (ADS)

Henri, P.; Vallières, X.; Gilet, N.; Hajra, R.; Moré, J.; Goetz, C.; Richter, I.; Glassmeier, K. H.; Galand, M. F.; Heritier, K. L.; Eriksson, A. I.; Nemeth, Z.; Tsurutani, B.; Rubin, M.; Altwegg, K.

2016-12-01

At distances close enough to the Sun, when comets are characterised by a significant outgassing, the cometary neutral density may become large enough for both the cometary plasma and the cometary gas to be coupled, through ion-neutral and electron-neutral collisions. This coupling enables the formation of an unmagnetised expanding cometary ionosphere around the comet nucleus, also called diamagnetic cavity, within which the solar wind magnetic field cannot penetrate. The instruments of the Rosetta Plasma Consortium (RPC), onboard the Rosetta Orbiter, enable us to better constrain the structure, dynamics and stability of the plasma around comet 67P/CG. Recently, magnetic field measurements (RPC-MAG) have shown the existence of such a diamagnetic region around comet 67P/CG [Götz et al., 2016]. Contrary to a single, large scale, diamagnetic cavity such as what was observed around comet Halley, Rosetta have crossed several diamagnetic structures along its trajectory around comet 67P/CG. Using electron density measurements from the Mutual Impedance Probe (RPC-MIP) during the different diamagnetic cavity crossings, identified by the flux gate magnetometer (RPC-MAG), we map the unmagnetised plasma density around comet 67P/CG. Our aims is to better constrain the structure, dynamics and stability of this inner cometary plasma layer characterised by cold electrons (as witnessed by the Langmuir Probes RPC-LAP). The ionisation ratio in these unmagnetised region(s) is computed from the measured electron (RPC-MIP) and neutral gas (ROSINA/COPS) densities. In order to assess the importance of solar EUV radiation as a source of ionisation, the observed electron density will be compared to a the density expected from an ionospheric model taking into account solar radiation absorption. The crossings of diamagnetic region(s) by Rosetta show that the unmagnetised cometary plasma is particularly homogeneous, compared to the highly dynamical magnetised plasma observed in adjacent magnetised regions. Moreover, during the crossings of multiple, successive diamagnetic region(s) over time scales of tens of minutes or hours, the plasma density is almost identical in the different unmagnetised regions, suggesting that these unmagnetised regions may be a single diamagnetic structure crossed several times by Rosetta.

Determination of temperature maps of EUV coronal hole jets

NASA Astrophysics Data System (ADS)

Nisticò, Giuseppe; Patsourakos, Spiros; Bothmer, Volker; Zimbardo, Gaetano

2011-11-01

Coronal hole jets are fast ejections of plasma occurring within coronal holes, observed at Extreme-UltraViolet (EUV) and X-ray wavelengths. Recent observations of jets by the STEREO and Hinode missions show that they are transient phenomena which occur at much higher rates than large-scale impulsive phenomena like flares and Coronal Mass Ejections (CMEs). In this paper we describe some typical characteristics of coronal jets observed by the SECCHI instruments of STEREO spacecraft. We show an example of 3D reconstruction of the helical structure for a south pole jet, and present how the angular distribution of the jet position angles changes from the Extreme-UltraViolet-Imager (EUVI) field of view to the CORonagraph1 (COR1) (height ∼2.0 R⊙ heliocentric distance) field of view. Then we discuss a preliminary temperature determination for the jet plasma by using the filter ratio method at 171 and 195 Å and applying a technique for subtracting the EUV background radiation. The results show that jets are characterized by electron temperatures ranging between 0.8 and 1.3 MK. We present the thermal structure of the jet as temperature maps and we describe its thermal evolution.

Investigation of high power impulse magnetron sputtering (HIPIMS) discharge using fast ICCD camera

NASA Astrophysics Data System (ADS)

Hecimovic, Ante

2012-10-01

High power impulse magnetron sputtering (HIPIMS) combines impulse glow discharges at power levels up to the MW range with conventional magnetron cathodes to achieve a highly ionised sputtered flux. The dynamics of the HIPIMS discharge was investigated using fast Intensified Charge Coupled Device (ICCD) camera. In the first experiment the HIPIMS plasma was recorded from the side with goal to analyse the plasma intensity using Abel inversion to obtain the emissivity maps of the plasma species. Resulting emissivity maps provide the information on the spatial distribution of Ar and sputtered material and evolution of the plasma chemistry above the cathode. In the second experiment the plasma emission was recorded with camera facing the target. The images show that the HIPIMS plasma develops drift wave type instabilities characterized by well defined regions of high and low plasma emissivity along the racetrack of the magnetron. The instabilities cause periodic shifts in the floating potential. The structures rotate in ExB direction at velocities of 10 kms-1 and frequencies up to 200 kHz. The high emissivity regions comprise Ar and metal ion emission with strong Ar and metal neutral emission depletion. A detailed analysis of the temporal evolution of the saturated instabilities using four consequently triggered fast ICCD cameras is presented. Furthermore working gas pressure and discharge current variation showed that the shape and the speed of the instability strongly depend on the working gas and target material combination. In order to better understand the mechanism of the instability, different optical interference band pass filters (of metal and gas atom, and ion lines) were used to observe the spatial distribution of each species within the instability.

Angiotensin converting enzyme 2 activity and human atrial fibrillation: increased plasma angiotensin converting enzyme 2 activity is associated with atrial fibrillation and more advanced left atrial structural remodelling.

PubMed

Walters, Tomos E; Kalman, Jonathan M; Patel, Sheila K; Mearns, Megan; Velkoska, Elena; Burrell, Louise M

2017-08-01

Angiotensin converting enzyme 2 (ACE2) is an integral membrane protein whose main action is to degrade angiotensin II. Plasma ACE2 activity is increased in various cardiovascular diseases. We aimed to determine the relationship between plasma ACE2 activity and human atrial fibrillation (AF), and in particular its relationship to left atrial (LA) structural remodelling. One hundred and three participants from a tertiary arrhythmia centre, including 58 with paroxysmal AF (PAF), 20 with persistent AF (PersAF), and 25 controls, underwent clinical evaluation, echocardiographic analysis, and measurement of plasma ACE2 activity. A subgroup of 20 participants underwent invasive LA electroanatomic mapping. Plasma ACE2 activity levels were increased in AF [control 13.3 (9.5-22.3) pmol/min/mL; PAF 16.9 (9.7-27.3) pmol/min/mL; PersAF 22.8 (13.7-33.4) pmol/min/mL, P = 0.006]. Elevated plasma ACE2 was associated with older age, male gender, hypertension and vascular disease, elevated left ventricular (LV) mass, impaired LV diastolic function and advanced atrial disease (P < 0.05 for all). Independent predictors of elevated plasma ACE2 activity were AF (P = 0.04) and vascular disease (P < 0.01). There was a significant relationship between elevated ACE2 activity and low mean LA bipolar voltage (adjusted R2 = 0.22, P = 0.03), a high proportion of complex fractionated electrograms (R2 = 0.32, P = 0.009) and a long LA activation time (R2 = 0.20, P = 0.04). Plasma ACE2 activity is elevated in human AF. Both AF and vascular disease predict elevated plasma ACE2 activity, and elevated plasma ACE2 is significantly associated with more advanced LA structural remodelling. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2016. For permissions please email: journals.permissions@oup.com.

Current density distributions and sputter marks in electron cyclotron resonance ion sources

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

Panitzsch, Lauri; Peleikis, Thies; Boettcher, Stephan

2013-01-15

Most electron cyclotron resonance ion sources use hexapolar magnetic fields for the radial confinement of the plasma. The geometry of this magnetic structure is then-induced by charged particles-mapped onto the inner side of the plasma electrode via sputtering and deposition. The resulting structures usually show two different patterns: a sharp triangular one in the central region which in some cases is even sputtered deep into the material (referred to as thin groove or sharp structure), and a blurred but still triangular-like one in the surroundings (referred to as broad halo). Therefore, both patterns seem to have different sources. To investigatemore » their origins we replaced the standard plasma electrode by a custom-built plasma electrode acting as a planar, multi-segment current-detector. For different biased disc voltages, detector positions, and source biases (referred to the detector) we measured the electrical current density distributions in the plane of the plasma electrode. The results show a strong and sharply confined electron population with triangular shape surrounded by less intense and spatially less confined ions. Observed sputter- and deposition marks are related to the analysis of the results. Our measurements suggest that the two different patterns (thin and broad) indeed originate from different particle populations. The thin structures seem to be caused by the hot electron population while the broad marks seem to stem from the medium to highly charged ions. In this paper we present our measurements together with theoretical considerations and substantiate the conclusions drawn above. The validity of these results is also discussed.« less

Method of azimuthally stable Mueller-matrix diagnostics of blood plasma polycrystalline films in cancer diagnostics

NASA Astrophysics Data System (ADS)

Ushenko, Yu. A.; Prysyazhnyuk, V. P.; Gavrylyak, M. S.; Gorsky, M. P.; Bachinskiy, V. T.; Vanchuliak, O. Ya.

2015-02-01

A new information optical technique of diagnostics of the structure of polycrystalline films of blood plasma is proposed. The model of Mueller-matrix description of mechanisms of optical anisotropy of such objects as optical activity, birefringence, as well as linear and circular dichroism is suggested. The ensemble of informationally topical azimuthally stable Mueller-matrix invariants is determined. Within the statistical analysis of such parameters distributions the objective criteria of differentiation of films of blood plasma taken from healthy and patients with liver cirrhosis were determined. From the point of view of probative medicine the operational characteristics (sensitivity, specificity and accuracy) of the information-optical method of Mueller-matrix mapping of polycrystalline films of blood plasma were found and its efficiency in diagnostics of liver cirrhosis was demonstrated. Prospects of application of the method in experimental medicine to differentiate postmortem changes of the myocardial tissue was examined.

Midlatitude Plasma Bubbles Over China and Adjacent Areas During a Magnetic Storm on 8 September 2017

NASA Astrophysics Data System (ADS)

Aa, Ercha; Huang, Wengeng; Liu, Siqing; Ridley, Aaron; Zou, Shasha; Shi, Liqin; Chen, Yanhong; Shen, Hua; Yuan, Tianjiao; Li, Jianyong; Wang, Tan

2018-03-01

This paper presents observations of postsunset super plasma bubbles over China and adjacent areas during the second main phase of a storm on 8 September 2017. The signatures of the plasma bubbles can be seen or deduced from (1) deep field-aligned total electron content depletions embedded in regional ionospheric maps derived from dense Global Navigation Satellite System networks, (2) significant equatorial and midlatitudinal plasma bite-outs in electron density measurements on board Swarm satellites, and (3) enhancements of ionosonde virtual height and scintillation in local evening associated with strong southward interplanetary magnetic field. The bubbles/depletions covered a broad area mainly within 20°-45°N and 80°-110°E with bifurcated structures and persisted for nearly 5 hr (˜13-18 UT). One prominent feature is that the bubbles extended remarkably along the magnetic field lines in the form of depleted flux tubes, reaching up to midlatitude of around 50°N (magnetic latitude: 45.5°N) that maps to an altitude of 6,600 km over the magnetic equator. The maximum upward drift speed of the bubbles over the magnetic equator was about 700 m/s and gradually decreased with altitude and time. The possible triggering mechanism of the plasma bubbles was estimated to be storm time eastward prompt penetration electric field, while the traveling ionospheric disturbance could play a role in facilitating the latitudinal extension of the depletions.

Vasopressin responses to unloading arterial baroreceptors during cardiac nerve blockade in conscious dogs

NASA Technical Reports Server (NTRS)

O'Donnell, C. P.; Keil, L. C.; Thrasher, T. N.

1992-01-01

We examined the relative contributions of afferent input from the heart and from arterial baroreceptors in the stimulation of arginine vasopressin (AVP) secretion in response to hypotension caused by thoracic inferior vena caval constriction (TIVCC). Afferent input from cardiac receptors was reversibly blocked by infusing 2% procaine into the pericardial space to anesthetize the cardiac nerves. Acute cardiac nerve blockade (CNB) alone caused a rise in mean arterial pressure (MAP) of 24 +/- 3 mmHg but no change in plasma AVP. If the rise in MAP was prevented by TIVCC, plasma AVP increased by 39 +/- 15 pg/ml, and if MAP was allowed to increase and then was forced back to control by TIVCC, plasma AVP increased by 34 +/- 15 pg/ml. Thus the rise in MAP during CNB stimulated arterial baroreceptors, which in turn compensated for the loss of inhibitory input from cardiac receptors on AVP secretion. These results indicate that the maximum secretory response resulting from complete unloading of cardiac receptors at a normal MAP results in a mean increase in plasma AVP of 39 pg/ml in this group of dogs. When MAP was reduced 25% below control levels (from 95 +/- 5 to 69 +/- 3 mmHg) by TIVCC during pericardial saline infusion, plasma AVP increased by 79 +/- 42 pg/ml. However, the same degree of hypotension during CNB (MAP was reduced from 120 +/- 5 to 71 +/- 3 mmHg) led to a greater (P less than 0.05) increase in plasma AVP of 130 +/- 33 pg/ml. Because completely unloading cardiac receptors can account for an increase of only 39 pg/ml on average in this group of dogs, the remainder of the increase in plasma AVP must be due to other sources of stimulation. We suggest that the principal stimulus to AVP secretion after acute CNB in these studies arises from unloading the arterial baroreceptors.

Lunar plasma measurement by MAP-PACE onboard KAGUYA (SELENE)

NASA Astrophysics Data System (ADS)

Saito, Yoshifumi

Low energy charged particles around the Moon were vigorously observed by Moon orbiting satellites and plasma instrumentation placed on the lunar surface in 1960s and 1970s. Though there were some satellites that explored the Moon afterwards, most of them were dedicated to the global mapping of the lunar surface. KAGUYA(SELENE) is a Japanese lunar orbiter that studies the origin and evolution of the Moon by means of global mapping of element abundances, mineralogical composition, and surface geographical mapping from 100km altitude. KAGUYA was successfully launched on 14 September 2007 by HIIA launch vehicle from Tanegashima Space Center in Japan. KAGUYA was inserted into a circular lunar polar orbit of 100km altitude and started continuous observation in mid-December 2007. One of the fourteen science instruments MAP-PACE (MAgnetic field and Plasma experiment - Plasma energy Angle and Composition Experiment) was developed for the comprehensive three-dimensional plasma measurement around the Moon. MAP-PACE consists of 4 sensors: ESA (Electron Spectrum Analyzer)-S1, ESA-S2, IMA (Ion Mass Analyzer), and IEA (Ion Energy Analyzer). ESA-S1 and S2 measure the distribution function of low energy electrons below 15keV. IMA and IEA measure the distribution function of low energy ions below 28keV/q. IMA has an ability to discriminate the ion mass with high mass resolution. PACE sensors have been measuring solar wind, plasmas in the wake region of the Moon and plasmas in the Earth's magnetosphere. ESA sensors have discovered electron heating over magnetic anomalies on the lunar surface. ESA sensors have also observed electrons accelerated from the lunar surface in the wake region. PACE ion sensors have discovered new features of low energy ions around the Moon. IMA has discovered the existence of alkali ions that are originated from the lunar surface or lunar atmosphere and are picked up by the solar wind. IEA and IMA sensors discovered solar wind reflection by the Moon. PACE ion sensors also discovered that ions are rarefied over the magnetic anomaly on the lunar surface while electrons are heated. MAP-PACE has been revealing unexpectedly active plasma environment around the Moon.

Direct chemical evidence for sphingolipid domains in the plasma membranes of fibroblasts [High-Resolution Chemical Imaging of Sphingolipid Distribution in the Plasma Membrane

DOE PAGES

Frisz, Jessica F.; Lou, Kaiyan; Klitzing, Haley A.; ...

2013-01-28

Sphingolipids play important roles in plasma membrane structure and cell signaling. Yet, their lateral distribution in the plasma membrane is poorly understood. Here we quantitatively analyzed the sphingolipid organization on the entire dorsal surface of intact cells by mapping the distribution of 15N-enriched ions from metabolically labeled 15N-sphingolipids in the plasma membrane using high-resolution imaging mass spectrometry. Many types of control experiments (internal, positive, negative, and fixation temperature), along with parallel experiments involving the imaging of fluorescent sphingolipids$-$both in living cells and during fixation of living cells$-$exclude potential artifacts. Micrometer-scale sphingolipid patches consisting of numerous 15Nsphingolipid microdomains with mean diametersmore » of ~200 nm are always present in the plasma membrane. Depletion of 30% of the cellular cholesterol did not eliminate the sphingolipid domains, but did reduce their abundance and long range organization in the plasma membrane. In contrast, disruption of the cytoskeleton eliminated the sphingolipid domains. These results indicate that these sphingolipid assemblages are not lipid rafts, and are instead a distinctly different type of sphingolipid-enriched plasma membrane domain that depends upon cortical actin.« less

Electron and ion distribution functions in magnetopause reconnection

NASA Astrophysics Data System (ADS)

Wang, S.; Chen, L. J.; Bessho, N.; Hesse, M.; Kistler, L. M.; Torbert, R. B.; Mouikis, C.; Pollock, C. J.

2015-12-01

We investigate electron and ion velocity distribution functions in dayside magnetopause reconnection events observed by the Cluster and MMS spacecraft. The goal is to build a spatial map of electron and ion distribution features to enable the indication of the spacecraft location in the reconnection structure, and to understand plasma energization processes. Distribution functions, together with electromagnetic field structures, plasma densities, and bulk velocities, are organized and compared with particle-in-cell simulation results to indicate the proximities to the reconnection X-line. Anisotropic features in the distributions of magnetospheric- and magnetosheath- origin electrons at different locations in the reconnection inflow and exhaust are identified. In particular, parallel electron heating is observed in both the magnetosheath and magnetosphere inflow regions. Possible effects of the guide field strength, waves, and upstream density and temperature asymmetries on the distribution features will be discussed.

Double-reconnected magnetic structures driven by Kelvin-Helmholtz vortices at the Earth's magnetosphere

NASA Astrophysics Data System (ADS)

Faganello, Matteo; Borgogno, Dario; Califano, Francesco; Pegoraro, Francesco

2015-11-01

In an almost collisionless MagnetoHydrodynamic plasma in a relatively strong magnetic field, stresses can be conveyed far from the region where they are exerted e.g., through the propagation of Alfvèn waves. The forced dynamics of line-tied magnetic structures in solar and stellar coronae is a paradigmatic case. We investigate how this action at a distance develops from the equatorial region of the Kelvin-Helmholtz unstable flanks of the Earth's magnetosphere leading to the onset, at mid latitude in both hemispheres, of correlated double magnetic field line reconnection events that can allow the solar wind plasma to enter the Earth's magnetosphere. This mid-latitude double reconnection process, first investigated in, has been confirmed here by following a large set of individual field lines using a method similar to a Poincarè map.

Density Structures, Dynamics, and Seasonal and Solar Cycle Modulations of Saturn's Inner Plasma Disk

NASA Astrophysics Data System (ADS)

Holmberg, M. K. G.; Shebanits, O.; Wahlund, J.-E.; Morooka, M. W.; Vigren, E.; André, N.; Garnier, P.; Persoon, A. M.; Génot, V.; Gilbert, L. K.

2017-12-01

We present statistical results from the Cassini Radio and Plasma Wave Science (RPWS) Langmuir probe measurements recorded during the time interval from orbit 3 (1 February 2005) to 237 (29 June 2016). A new and improved data analysis method to obtain ion density from the Cassini LP measurements is used to study the asymmetries and modulations found in the inner plasma disk of Saturn, between 2.5 and 12 Saturn radii (1 RS=60,268 km). The structure of Saturn's plasma disk is mapped, and the plasma density peak, nmax, is shown to be located at ˜4.6 RS and not at the main neutral source region at 3.95 RS. The shift in the location of nmax is due to that the hot electron impact ionization rate peaks at ˜4.6 RS. Cassini RPWS plasma disk measurements show a solar cycle modulation. However, estimates of the change in ion density due to varying EUV flux is not large enough to describe the detected dependency, which implies that an additional mechanism, still unknown, is also affecting the plasma density in the studied region. We also present a dayside/nightside ion density asymmetry, with nightside densities up to a factor of 2 larger than on the dayside. The largest density difference is found in the radial region 4 to 5 RS. The dynamic variation in ion density increases toward Saturn, indicating an internal origin of the large density variability in the plasma disk rather than being caused by an external source origin in the outer magnetosphere.

Effect of celecoxib on the antihypertensive effect of losartan in a rat model of renovascular hypertension.

PubMed

Boshra, Vivian; El Wakeel, Gehan Abdel Hamid; Nader, Manar A

2011-02-01

Certain nonsteroidal anti-inflammatory drugs have been reported to elevate blood pressure in some hypertensive patients, who are either untreated or treated with antihypertensive agents. This study was undertaken to determine the effect of a selective cyclooxygenase-2 (COX-2) inhibitor, celecoxib, on the antihypertensive effects of the angiotensin II type 1 receptor (AT1) antagonist, losartan potassium. We studied the effect of oral treatment with losartan (30 mg/kg), celecoxib (3 mg/kg), and their combination on the mean arterial blood pressure (MAP), plasma renin activity (PRA), and plasma prostaglandin E2 (PGE2) in male Sprague-Dawley rats with renovascular hypertension (RVH) induced by partial subdiaphragmatic aortic constriction. Treatment was continued for 7 days after aortic coarctation. Aortic coarctation led to significant increases in the MAP, PRA, and plasma PGE2. In RVH rats, losartan treatment caused a significant decrease of MAP with a significant increase in both plasma PGE2 and PRA. Celecoxib caused a nonsignificant change in MAP with a significant decrease in the raised levels of plasma PGE2 and PRA. Concomitant administration of celecoxib and losartan did not significantly affect the lowering effect of losartan on MAP with a subsequent significant decrease in the plasma PGE2 and PRA in RVH rats. Therefore, celecoxib could be used in renin-dependent hypertensive patients who receive losartan, without fear of a rise in their blood pressure.

Plasma in Saturn's Nightside Magnetosphere and the Implications for Global Circulation

NASA Technical Reports Server (NTRS)

McAndrews, H.J.; Thomsen, M.F.; Arridge, C.S.; Jackman, C.M.; Wilson, R.J.; Henderson, M.G.; Tokar, R.L.; Khurana, K.K.; Sittler, E. C.; Coates, A.J.;

Placental growth factor (PlGF) is a surrogate marker in preeclamptic hypertension.

PubMed

Teixeira, Patrícia Gonçalves; Cabral, Antônio Carlos Vieira; Andrade, Silvia Passos; Reis, Zilma Silveira Nogueira; da Cruz, Lívia Pieroni Barroso; Pereira, Jacqueline Braga; Martins, Breno Oliveira de Barcelos; Rezende, Cezar Alencar de Lima

2008-01-01

To evaluate plasma levels of angiogenic factors and their association with preeclampsia. Twenty-three women with preeclampsia and nine normotensive pregnant women from the Maternity of Hospital das Clínicas of Belo Horizonte/MG-Brazil were assessed by National High Blood Pressure Education Program Working Group Creteria (NHBPEPWG). The plasma levels of vascular endothelial growth factor (VEGF) and Placental growth factor (PlGF) were determined by ELISA assay. Plasma concentration of PlGF was 12-fold lower in preeclampsia versus non preeclampsia pregnancies. An inverse correlation was observed between PlGF plasma levels and mean arterial pressure (MAP); a decrease in 1pg/mL of PlGF resulted in 6.18 mm Hg increase in MAP. These results indicate that PlGF is related to MAP in pregnant women.

Comment on 'Mapping the dayside ionosphere to the magnetosphere according to particle precipitation characteristics' by Newell and Meng

NASA Technical Reports Server (NTRS)

Lockwood, M.; Smith, M. F.

1993-01-01

Newell and Meng (1992) present maps of the occurrence probability of various classifications of particle precipitation as seen in the dayside topside ionosphere. It is argued that these are maps of the magnetospheric regions, a contention with which their critics disagree. The latter conclude that, because of convection, any one population of particles seen at low altitudes will have originated from a wide variety of locations, and particle characteristics cannot be mapped back to those in the magnetosphere without detailed knowledge of both the convection and magnetic field. Steplike boundaries between the regions will arise from nonsteady-state conditions and cannot be envisaged as steady-state magnetospheric boundaries between two plasma populations. In their reply Newell and Meng contend that convection does not move plasma from the LLBL into the cusp. Most of the LLBL plasma comes from the magnetosheath, so the direction of plasma transfer is in the other direction.

Development and characterization of plasma targets for controlled injection of electrons into laser-driven wakefields

NASA Astrophysics Data System (ADS)

Kleinwaechter, Tobias; Goldberg, Lars; Palmer, Charlotte; Schaper, Lucas; Schwinkendorf, Jan-Patrick; Osterhoff, Jens

2012-10-01

Laser-driven wakefield acceleration within capillary discharge waveguides has been used to generate high-quality electron bunches with GeV-scale energies. However, owing to fluctuations in laser and plasma conditions in combination with a difficult to control self-injection mechanism in the non-linear wakefield regime these bunches are often not reproducible and can feature large energy spreads. Specialized plasma targets with tailored density profiles offer the possibility to overcome these issues by controlling the injection and acceleration processes. This requires precise manipulation of the longitudinal density profile. Therefore our target concept is based on a capillary structure with multiple gas in- and outlets. Potential target designs are simulated using the fluid code OpenFOAM and those meeting the specified criteria are fabricated using femtosecond-laser machining of structures into sapphire plates. Density profiles are measured over a range of inlet pressures utilizing gas-density profilometry via Raman scattering and pressure calibration with longitudinal interferometry. In combination these allow absolute density mapping. Here we report the preliminary results.

XMM-Newton observations of the supernova remnant IC 443. II. Evidence of stellar ejecta in the inner regions

NASA Astrophysics Data System (ADS)

Troja, E.; Bocchino, F.; Miceli, M.; Reale, F.

2008-07-01

Aims: We investigate the spatial distribution of the physical and chemical properties of the hot X-ray emitting plasma of the supernova remnant IC 443, to derive important constraints on its ionization stage, on the progenitor supernova explosion, on the age of the remnant, and its physical association with a close pulsar wind nebula. Methods: We present XMM-Newton images of IC 443, a median photon energy map, silicon and sulfur equivalent width maps, and a spatially resolved spectral analysis of a set of homogeneous regions. Results: The hard X-ray thermal emission (1.4-5.0 keV) of IC 443 displays a centrally-peaked morphology, its brightness peaks being associated with hot (kT > 1 keV) X-ray emitting plasma. A ring-shaped structure, characterized by high values of equivalent widths and median photon energy, encloses the PWN. Its hard X-ray emission is spectrally characterized by a collisional ionization equilibrium model, and strong emission lines of Mg, Si, and S, requiring oversolar metal abundances. Dynamically, the location of the ejecta ring suggests an SNR age of ~4000 yr. The presence of overionized plasma in the inner regions of IC 443, addressed in previous works, is much less evident in our observations.

Plasma Radiation and Acceleration Effectiveness of CME-driven Shocks

NASA Astrophysics Data System (ADS)

Gopalswamy, N.; Schmidt, J. M.

2008-05-01

CME-driven shocks are effective radio radiation generators and accelerators for Solar Energetic Particles (SEPs). We present simulated 3 D time-dependent radio maps of second order plasma radiation generated by CME- driven shocks. The CME with its shock is simulated with the 3 D BATS-R-US CME model developed at the University of Michigan. The radiation is simulated using a kinetic plasma model that includes shock drift acceleration of electrons and stochastic growth theory of Langmuir waves. We find that in a realistic 3 D environment of magnetic field and solar wind outflow of the Sun the CME-driven shock shows a detailed spatial structure of the density, which is responsible for the fine structure of type II radio bursts. We also show realistic 3 D reconstructions of the magnetic cloud field of the CME, which is accelerated outward by magnetic buoyancy forces in the diverging magnetic field of the Sun. The CME-driven shock is reconstructed by tomography using the maximum jump in the gradient of the entropy. In the vicinity of the shock we determine the Alfven speed of the plasma. This speed profile controls how steep the shock can grow and how stable the shock remains while propagating away from the Sun. Only a steep shock can provide for an effective particle acceleration.

Plasma radiation and acceleration effectiveness of CME-driven shocks

NASA Astrophysics Data System (ADS)

Schmidt, Joachim

CME-driven shocks are effective radio radiation generators and accelerators for Solar Energetic Particles (SEPs). We present simulated 3 D time-dependent radio maps of second order plasma radiation generated by CME-driven shocks. The CME with its shock is simulated with the 3 D BATS-R-US CME model developed at the University of Michigan. The radiation is simulated using a kinetic plasma model that includes shock drift acceleration of electrons and stochastic growth theory of Langmuir waves. We find that in a realistic 3 D environment of magnetic field and solar wind outflow of the Sun the CME-driven shock shows a detailed spatial structure of the density, which is responsible for the fine structure of type II radio bursts. We also show realistic 3 D reconstructions of the magnetic cloud field of the CME, which is accelerated outward by magnetic buoyancy forces in the diverging magnetic field of the Sun. The CME-driven shock is reconstructed by tomography using the maximum jump in the gradient of the entropy. In the vicinity of the shock we determine the Alfven speed of the plasma. This speed profile controls how steep the shock can grow and how stable the shock remains while propagating away from the Sun. Only a steep shock can provide for an effective particle acceleration.

A method to accelerate creation of plasma etch recipes using physics and Bayesian statistics

NASA Astrophysics Data System (ADS)

Chopra, Meghali J.; Verma, Rahul; Lane, Austin; Willson, C. G.; Bonnecaze, Roger T.

2017-03-01

Next generation semiconductor technologies like high density memory storage require precise 2D and 3D nanopatterns. Plasma etching processes are essential to achieving the nanoscale precision required for these structures. Current plasma process development methods rely primarily on iterative trial and error or factorial design of experiment (DOE) to define the plasma process space. Here we evaluate the efficacy of the software tool Recipe Optimization for Deposition and Etching (RODEo) against standard industry methods at determining the process parameters of a high density O2 plasma system with three case studies. In the first case study, we demonstrate that RODEo is able to predict etch rates more accurately than a regression model based on a full factorial design while using 40% fewer experiments. In the second case study, we demonstrate that RODEo performs significantly better than a full factorial DOE at identifying optimal process conditions to maximize anisotropy. In the third case study we experimentally show how RODEo maximizes etch rates while using half the experiments of a full factorial DOE method. With enhanced process predictions and more accurate maps of the process space, RODEo reduces the number of experiments required to develop and optimize plasma processes.

Reconstruction of flux coordinates from discretized magnetic field maps

NASA Astrophysics Data System (ADS)

Predebon, I.; Momo, B.; Suzuki, Y.; Auriemma, F.

2018-04-01

We provide a simple method to build a straight field-line coordinate system from discretized (Poincaré) magnetic field maps. The method is suitable for any plasma domain with nested flux surfaces, including magnetic islands. Illustrative examples are shown for tokamak, heliotron, and reversed-field-pinch plasmas with m = 1 islands.

Schlieren Cinematography of Current Driven Plasma Jet Dynamics

NASA Astrophysics Data System (ADS)

Loebner, Keith; Underwood, Thomas; Cappelli, Mark

2016-10-01

Schlieren cinematography of a pulsed plasma deflagration jet is presented and analyzed. An ultra-high frame rate CMOS camera coupled to a Z-type laser Schlieren apparatus is used to obtain flow-field refractometry data for the continuous flow Z-pinch formed within the plasma deflagration jet. The 10 MHz frame rate for 256 consecutive frames provides high temporal resolution, enabling turbulent fluctuations and plasma instabilities to be visualized over the course of a single pulse (20 μs). The Schlieren signal is radiometrically calibrated to obtain a two dimensional mapping of the refraction angle of the axisymmetric pinch plasma, and this mapping is then Abel inverted to derive the plasma density distribution as a function radius, axial coordinate, and time. Analyses of previously unknown discharge characteristics and comparisons with prior work are discussed.

MetaMapp: mapping and visualizing metabolomic data by integrating information from biochemical pathways and chemical and mass spectral similarity

PubMed Central

2012-01-01

Background Exposure to environmental tobacco smoke (ETS) leads to higher rates of pulmonary diseases and infections in children. To study the biochemical changes that may precede lung diseases, metabolomic effects on fetal and maternal lungs and plasma from rats exposed to ETS were compared to filtered air control animals. Genome- reconstructed metabolic pathways may be used to map and interpret dysregulation in metabolic networks. However, mass spectrometry-based non-targeted metabolomics datasets often comprise many metabolites for which links to enzymatic reactions have not yet been reported. Hence, network visualizations that rely on current biochemical databases are incomplete and also fail to visualize novel, structurally unidentified metabolites. Results We present a novel approach to integrate biochemical pathway and chemical relationships to map all detected metabolites in network graphs (MetaMapp) using KEGG reactant pair database, Tanimoto chemical and NIST mass spectral similarity scores. In fetal and maternal lungs, and in maternal blood plasma from pregnant rats exposed to environmental tobacco smoke (ETS), 459 unique metabolites comprising 179 structurally identified compounds were detected by gas chromatography time of flight mass spectrometry (GC-TOF MS) and BinBase data processing. MetaMapp graphs in Cytoscape showed much clearer metabolic modularity and complete content visualization compared to conventional biochemical mapping approaches. Cytoscape visualization of differential statistics results using these graphs showed that overall, fetal lung metabolism was more impaired than lungs and blood metabolism in dams. Fetuses from ETS-exposed dams expressed lower lipid and nucleotide levels and higher amounts of energy metabolism intermediates than control animals, indicating lower biosynthetic rates of metabolites for cell division, structural proteins and lipids that are critical for in lung development. Conclusions MetaMapp graphs efficiently visualizes mass spectrometry based metabolomics datasets as network graphs in Cytoscape, and highlights metabolic alterations that can be associated with higher rate of pulmonary diseases and infections in children prenatally exposed to ETS. The MetaMapp scripts can be accessed at http://metamapp.fiehnlab.ucdavis.edu. PMID:22591066

Plasma proteins predict conversion to dementia from prodromal disease

PubMed Central

Hye, Abdul; Riddoch-Contreras, Joanna; Baird, Alison L.; Ashton, Nicholas J.; Bazenet, Chantal; Leung, Rufina; Westman, Eric; Simmons, Andrew; Dobson, Richard; Sattlecker, Martina; Lupton, Michelle; Lunnon, Katie; Keohane, Aoife; Ward, Malcolm; Pike, Ian; Zucht, Hans Dieter; Pepin, Danielle; Zheng, Wei; Tunnicliffe, Alan; Richardson, Jill; Gauthier, Serge; Soininen, Hilkka; Kłoszewska, Iwona; Mecocci, Patrizia; Tsolaki, Magda; Vellas, Bruno; Lovestone, Simon

2014-01-01

Background The study aimed to validate previously discovered plasma biomarkers associated with AD, using a design based on imaging measures as surrogate for disease severity and assess their prognostic value in predicting conversion to dementia. Methods Three multicenter cohorts of cognitively healthy elderly, mild cognitive impairment (MCI), and AD participants with standardized clinical assessments and structural neuroimaging measures were used. Twenty-six candidate proteins were quantified in 1148 subjects using multiplex (xMAP) assays. Results Sixteen proteins correlated with disease severity and cognitive decline. Strongest associations were in the MCI group with a panel of 10 proteins predicting progression to AD (accuracy 87%, sensitivity 85%, and specificity 88%). Conclusions We have identified 10 plasma proteins strongly associated with disease severity and disease progression. Such markers may be useful for patient selection for clinical trials and assessment of patients with predisease subjective memory complaints. PMID:25012867

Plasma proteins predict conversion to dementia from prodromal disease.

PubMed

Hye, Abdul; Riddoch-Contreras, Joanna; Baird, Alison L; Ashton, Nicholas J; Bazenet, Chantal; Leung, Rufina; Westman, Eric; Simmons, Andrew; Dobson, Richard; Sattlecker, Martina; Lupton, Michelle; Lunnon, Katie; Keohane, Aoife; Ward, Malcolm; Pike, Ian; Zucht, Hans Dieter; Pepin, Danielle; Zheng, Wei; Tunnicliffe, Alan; Richardson, Jill; Gauthier, Serge; Soininen, Hilkka; Kłoszewska, Iwona; Mecocci, Patrizia; Tsolaki, Magda; Vellas, Bruno; Lovestone, Simon

2014-11-01

The study aimed to validate previously discovered plasma biomarkers associated with AD, using a design based on imaging measures as surrogate for disease severity and assess their prognostic value in predicting conversion to dementia. Three multicenter cohorts of cognitively healthy elderly, mild cognitive impairment (MCI), and AD participants with standardized clinical assessments and structural neuroimaging measures were used. Twenty-six candidate proteins were quantified in 1148 subjects using multiplex (xMAP) assays. Sixteen proteins correlated with disease severity and cognitive decline. Strongest associations were in the MCI group with a panel of 10 proteins predicting progression to AD (accuracy 87%, sensitivity 85%, and specificity 88%). We have identified 10 plasma proteins strongly associated with disease severity and disease progression. Such markers may be useful for patient selection for clinical trials and assessment of patients with predisease subjective memory complaints. Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.

MAVEN Mapping of Plasma Clouds Near Mars

NASA Astrophysics Data System (ADS)

Hurley, D.; Tran, T.; DiBraccio, G. A.; Espley, J. R.; Soobiah, Y. I. J.

2017-12-01

Brace et al. identified parcels of ionospheric plasma above the nominal ionosphere of Venus, dubbed plasma clouds. These were envisioned as instabilities on the ionopause that evolved to escaping parcels of ionospheric plasma. Mars Global Surveyor (MGS) Electron Reflectometer (ER) also detected signatures of ionospheric plasma above the nominal ionopause of Mars. Initial examination of the MGS ER data suggests that plasma clouds are more prevalent at Mars than at Venus, and similarly exhibit a connection to rotations in the upstream Interplanetary Magnetic Field (IMF) as Zhang et al. showed at Venus. We examine electron data from Mars to determine the locations of plasma clouds in the near-Mars environment using MGS and MAVEN data. The extensive coverage of the MAVEN orbit enables mapping an occurrence rate of the photoelectron spectra in Solar Wind Electron Analyzer (SWEA) data spanning all relevant altitudes and solar zenith angles. Martian plasma clouds are observed near the terminator like at Venus. They move to higher altitude as solar zenith angle increases, consistent with the escaping plasma hypothesis.

UAH/NASA Workshop on The Uses of a Tethered Satellite System

NASA Technical Reports Server (NTRS)

Wu, S. T. (Editor)

1978-01-01

Potential applications of the system are categorized into four areas: geological applications, atmospheric applications, electrodynamics and plasma studies, and technology applications. The multiple-use tethered system with feedback control, will be capable of supporting a payload or satellite suspended from the Shuttle cargo bay, at distances up to 100 kilometers from the Shuttle. Experiments proposed include: geomagnetic mapping, lower atmospheric measurements, ionospheric interactions with large space structures, solar wind transport, and magnetohydrodynamic measurements.

Hα Doppler shifts in a tornado in the solar corona

NASA Astrophysics Data System (ADS)

Schmieder, B.; Mein, P.; Mein, N.; Levens, P. J.; Labrosse, N.; Ofman, L.

2017-01-01

Context. High resolution movies in 193 Å from the Atmospheric Imaging Assembly (AIA) on the Solar Dynamic Observatory (SDO) show apparent rotation in the leg of a prominence observed during a coordinated campaign. Such structures are commonly referred to as tornadoes. Time-distance intensity diagrams of the AIA data show the existence of oscillations suggesting that the structure is rotating. Aims: The aim of this paper is to understand if the cool plasma at chromospheric temperatures inside the tornado is rotating around its central axis. Methods: The tornado was also observed in Hα with a cadence of 30 s by the MSDP spectrograph, operating at the Solar Tower in Meudon. The MSDP provides sequences of simultaneous spectra in a 2D field of view from which a cube of Doppler velocity maps is retrieved. Results: The Hα Doppler maps show a pattern with alternatively blueshifted and redshifted areas of 5 to 10'' wide. Over time the blueshifted areas become redshifted and vice versa, with a quasi-periodicity of 40 to 60 min. Weaker amplitude oscillations with periods of 4 to 6 min are superimposed onto these large period oscillations. Conclusions: The Doppler pattern observed in Hα cannot be interpreted as rotation of the cool plasma inside the tornado. The Hα velocity observations give strong constraints on the possible interpretations of the AIA tornado.

Stochastic layer scaling in the two-wire model for divertor tokamaks

NASA Astrophysics Data System (ADS)

Ali, Halima; Punjabi, Alkesh; Boozer, Allen

2009-06-01

The question of magnetic field structure in the vicinity of the separatrix in divertor tokamaks is studied. The authors have investigated this problem earlier in a series of papers, using various mathematical techniques. In the present paper, the two-wire model (TWM) [Reiman, A. 1996 Phys. Plasmas 3, 906] is considered. It is noted that, in the TWM, it is useful to consider an extra equation expressing magnetic flux conservation. This equation does not add any more information to the TWM, since the equation is derived from the TWM. This equation is useful for controlling the step size in the numerical integration of the TWM equations. The TWM with the extra equation is called the flux-preserving TWM. Nevertheless, the technique is apparently still plagued by numerical inaccuracies when the perturbation level is low, resulting in an incorrect scaling of the stochastic layer width. The stochastic broadening of the separatrix in the flux-preserving TWM is compared with that in the low mn (poloidal mode number m and toroidal mode number n) map (LMN) [Ali, H., Punjabi, A., Boozer, A. and Evans, T. 2004 Phys. Plasmas 11, 1908]. The flux-preserving TWM and LMN both give Boozer-Rechester 0.5 power scaling of the stochastic layer width with the amplitude of magnetic perturbation when the perturbation is sufficiently large [Boozer, A. and Rechester, A. 1978, Phys. Fluids 21, 682]. The flux-preserving TWM gives a larger stochastic layer width when the perturbation is low, while the LMN gives correct scaling in the low perturbation region. Area-preserving maps such as the LMN respect the Hamiltonian structure of field line trajectories, and have the added advantage of computational efficiency. Also, for a $1\\frac12$ degree of freedom Hamiltonian system such as field lines, maps do not give Arnold diffusion.

QUIESCENT PROMINENCES IN THE ERA OF ALMA: SIMULATED OBSERVATIONS USING THE 3D WHOLE-PROMINENCE FINE STRUCTURE MODEL

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

Gunár, Stanislav; Heinzel, Petr; Mackay, Duncan H.

2016-12-20

We use the detailed 3D whole-prominence fine structure model to produce the first simulated high-resolution ALMA observations of a modeled quiescent solar prominence. The maps of synthetic brightness temperature and optical thickness shown in the present paper are produced using a visualization method for synthesis of the submillimeter/millimeter radio continua. We have obtained the simulated observations of both the prominence at the limb and the filament on the disk at wavelengths covering a broad range that encompasses the full potential of ALMA. We demonstrate here extent to which the small-scale and large-scale prominence and filament structures will be visible inmore » the ALMA observations spanning both the optically thin and thick regimes. We analyze the relationship between the brightness and kinetic temperature of the prominence plasma. We also illustrate the opportunities ALMA will provide for studying the thermal structure of the prominence plasma from the cores of the cool prominence fine structure to the prominence–corona transition region. In addition, we show that detailed 3D modeling of entire prominences with their numerous fine structures will be important for the correct interpretation of future ALMA observations of prominences.« less

Use of Hilbert Curves in Parallelized CUDA code: Interaction of Interstellar Atoms with the Heliosphere

NASA Astrophysics Data System (ADS)

Destefano, Anthony; Heerikhuisen, Jacob

2015-04-01

Fully 3D particle simulations can be a computationally and memory expensive task, especially when high resolution grid cells are required. The problem becomes further complicated when parallelization is needed. In this work we focus on computational methods to solve these difficulties. Hilbert curves are used to map the 3D particle space to the 1D contiguous memory space. This method of organization allows for minimized cache misses on the GPU as well as a sorted structure that is equivalent to an octal tree data structure. This type of sorted structure is attractive for uses in adaptive mesh implementations due to the logarithm search time. Implementations using the Message Passing Interface (MPI) library and NVIDIA's parallel computing platform CUDA will be compared, as MPI is commonly used on server nodes with many CPU's. We will also compare static grid structures with those of adaptive mesh structures. The physical test bed will be simulating heavy interstellar atoms interacting with a background plasma, the heliosphere, simulated from fully consistent coupled MHD/kinetic particle code. It is known that charge exchange is an important factor in space plasmas, specifically it modifies the structure of the heliosphere itself. We would like to thank the Alabama Supercomputer Authority for the use of their computational resources.

Observation of the magnetospheric ``sash'' and its implications relative to solar-wind/magnetospheric coupling: A multisatellite event analysis

NASA Astrophysics Data System (ADS)

Maynard, N. C.; Savin, S.; Erickson, G. M.; Kawano, H.; Němeček, Z.; Peterson, W. K.; Šafránoková, J.; Sandahl, I.; Scudder, J. D.; Siscoe, G. L.; Sonnerup, B. U. Ö.; Weimer, D. R.; White, W. W.; Wilson, G. R.

2001-04-01

Using a unique data set from the Wind, Polar, Interball 1, Magion 4, and Defense Meteorological Satellite Program (DMSP) F11 satellites, comparisons with the Integrated Space Weather Model (ISM) have provided validation of the global structure predicted by the ISM model, which in turn has allowed us to use the model to interpret the data to further understand boundary layers and magnetospheric processes. The comparisons have shown that the magnetospheric ``sash'' [White et al., 1998], a region of low magnetic field discovered by the MHD modeling which extends along the high-latitude flank of the magnetopause, is related to the turbulent boundary layer on the high-latitude magnetopause, recently mapped by Interball 1. The sash in the data and in the model has rotational discontinuity properties, expected for a reconnection site. At some point near or behind the terminator, the sash becomes a site for reconnection of open field lines, which were previously opened by merging on the dayside. This indicates that significant reconnection in the magnetotail occurs on the flanks. Polar mapped to the high-density extension of the sash into the tilted plasma sheet. The source of the magnetosheath plasma observed by Polar on closed field lines behind the terminator was plasma entry through the low field connection of the sash to the central plasma sheet. The Polar magnetic field line footprints in each hemisphere are moving in different directions. Above and below the tilted plasma sheet the flows in the model are consistent with the corresponding flows in the ionosphere. The turbulence in the plasma sheet allows the convection patterns from each hemisphere to adjust. The boundary layer in the equatorial plane on the flank for this interplanetary magnetic field BY condition, which is below the tilted central plasma sheet, is several RE thick and is on tailward flowing open field lines. This thick boundary layer shields the magnetopause from viscous forces and must be driven by magnetic tension. Above the plasma sheet the boundary layer is dominated by the sash, and the model indicates that the open region inside the sash is considerably thinner.

System of multifunctional Jones matrix tomography of phase anisotropy in diagnostics of endometriosis

NASA Astrophysics Data System (ADS)

Ushenko, V. O.; Koval, G. D.; Ushenko, Yu. O.; Pidkamin, L. Y.; Sidor, M. I.; Vanchuliak, O.; Motrich, A. V.; Gorsky, M. P.; Meglinskiy, I.

2017-09-01

The paper presents the results of Jones-matrix mapping of uterine wall histological sections with second-degree and third-degree endometriosis. The technique of experimental measurement of coordinate distributions of the modulus and phase values of Jones matrix elements is suggested. Within the statistical and cross-correlation approaches the modulus and phase maps of Jones matrix images of optically thin biological layers of polycrystalline films of plasma and cerebrospinal fluid are analyzed. A set of objective parameters (statistical and generalized correlation moments), which are the most sensitive to changes in the phase of anisotropy, associated with the features of polycrystalline structure of uterine wall histological sections with second-degree and third-degree endometriosis are determined.

Plasma Composition in a Sigmoidal Anemone Active Region

NASA Astrophysics Data System (ADS)

Baker, D.; Brooks, D. H.; Démoulin, P.; van Driel-Gesztelyi, L.; Green, L. M.; Steed, K.; Carlyle, J.

2013-11-01

Using spectra obtained by the EUV Imaging Spectrometer (EIS) instrument onboard Hinode, we present a detailed spatially resolved abundance map of an active region (AR)-coronal hole (CH) complex that covers an area of 359'' × 485''. The abundance map provides first ionization potential (FIP) bias levels in various coronal structures within the large EIS field of view. Overall, FIP bias in the small, relatively young AR is 2-3. This modest FIP bias is a consequence of the age of the AR, its weak heating, and its partial reconnection with the surrounding CH. Plasma with a coronal composition is concentrated at AR loop footpoints, close to where fractionation is believed to take place in the chromosphere. In the AR, we found a moderate positive correlation of FIP bias with nonthermal velocity and magnetic flux density, both of which are also strongest at the AR loop footpoints. Pathways of slightly enhanced FIP bias are traced along some of the loops connecting opposite polarities within the AR. We interpret the traces of enhanced FIP bias along these loops to be the beginning of fractionated plasma mixing in the loops. Low FIP bias in a sigmoidal channel above the AR's main polarity inversion line, where ongoing flux cancellation is taking place, provides new evidence of a bald patch magnetic topology of a sigmoid/flux rope configuration.

Numerical studies of nonlocal effects of the low mode numbers tearing modes and their mitigation in the DIII-D

NASA Astrophysics Data System (ADS)

Punjabi, Alkesh; Ali, Halima; Evans, Todd

2006-10-01

In this work, the method of maps [1-4] is used to study the trajectories of magnetic field lines in the DIII-D tokamak. Data from the DIII-D shot 115467 is used to determine the parameters in the maps. Effects of the m=1, n=±1 tearing modes and the dipole perturbation from the C-coils on the motion of field lines are calculated. Internal tearing modes produce non-local effects on the magnetic footprints, and destroy their symmetry. Dipole perturbations mitigate the effects of the tearing modes, spread the heat-flux on the plates over a wider area, reduce the peak heat-flux, and reorganize the phase space structure in a new pattern that has the same symmetry as that of the external perturbation. The low dimensionality of the system and its symplecticity impose severe restrictions on the motion of the system in phase space forcing it to take on the symmetry properties of the perturbations. This work is done under the DOE grant number DE-FG02-01ER54624. 1. A. Punjabi, A. Boozer, and A. Verma, Phys. Rev. lett., 69, 3322 (1992). 2. H. Ali, A. Punjabi, and A. Boozer, Phys. Plasmas 11, 4527 (2004). 3. A. Punjabi, H. Ali, and A. Boozer, Phys. Plasmas 10, 3992 (2003). 4. A. Punjabi, H. Ali, and A. Boozer, Phys. Plasmas 4, 337 (1997).

Far-Field RF Sheaths due to Shear Alfvén Waves in the LAPD

NASA Astrophysics Data System (ADS)

Martin, Michael; van Compernolle, Bart; Gekelman, Walter; Pribyl, Pat; Carter, Troy; D'Ippolito, Daniel A.; Myra, James R.

2013-10-01

Ion cyclotron resonance heating (ICRH) is an important tool in current fusion experiments and will be an essential heating component in ITER. ICRH could be limited by deleterious effects due to the formation of radio frequency (RF) sheaths in the near-field (at the antenna) and in the far-field (e.g. in the divertor region). Far-field sheaths are thought to be caused by the direct launch of or mode conversion to a shear Alfvén wave with an electric field component parallel to the background magnetic field at the wall. In this experiment a limiter plate was inserted into a cylindrical plasma in the LAPD (ne ~ 1010-11 cm-3, Te ~ 5 eV, B0 = 1.2 kG) and RF sheaths were created by directly launching the shear Alfven wave. Plasma potential measurements were made with an emissive probe. DC plasma potential rectification was observed along field lines connected to the plate, serving as an indirect measure of RF sheath formation. 2-D maps of plasma properties and rectified plasma potential will be presented. This research is part of an ongoing campaign to study the formation and structure of RF sheaths.

Potential Mapping of an Indium-Tin-Oxide Glass Box in a GEC Reference Cell

NASA Astrophysics Data System (ADS)

Kaplan, Rebecca; Carmona-Reyes, Jorge; Hyde, Truell; Matthews, Lorin; Casper Program Team

The use of indium-tin-oxide (ITO) coated boxes, as well as boxes coated with other substances, placed on or floating above the lower electrode in studies using Gaseous Electronics Conference Radio Frequency Reference Cells have increased in interest, as have the use of plain glass boxes. This increase in interest is due to the greater ability to control the confinement forces and in effect create dust chain structures which aid in studies within other areas of physics such as; entropy, kinetic dust temperature, plasma balls and coulomb explosions. Further analysis of the data obtained using these boxes shows what appear to be at least two different regions of confinement inside the boxes as well as some unexpected phenomena related to anomalous values and behavior of the electric field. These areas affect the dust to dust and dust to plasma interactions independently in the separate regions and are therefore of great interest. In this study electric potential and electric field maps created in MatLab with data obtained using two probes mounted on CASPER's S-100 nano-manipulator will be presented, connecting the information obtained from these maps to the behavior of the dust observed for different experimental conditions. All of this has been made possible by the opportunity and funding from the CASPER program and the National Science Foundation Grant Number PHY-1262031.

Spatial Studies of Ion Beams in an Expanding Plasma

NASA Astrophysics Data System (ADS)

Aguirre, Evan; Good, Timothy; Scime, Earl; Thompson, Derek

2017-10-01

We report spatially resolved perpendicular and parallel ion velocity distribution function (IVDF) measurements in an expanding argon helicon plasma. The parallel IVDFs, obtained through laser induced fluorescence (LIF), show an ion beam with v 8 km/s flowing downstream that is confined to the center of the discharge. The ion beam is confined to within a few centimeters radially and is measurable for tens of centimeters axially before the LIF signal fades, likely a result of metastable quenching of the beam ions. The axial ion beam velocity slows in agreement with collisional processes. The perpendicular IVDFs show an ion population with a radially outward flow that increases with radial location. The DC electric field, electron temperature, and the plasma density in the double layer plume are all consistent with magnetic field aligned structures. The upstream and downstream electric field measurements show clear evidence of an ion hole that maps along the magnetic field at the edge of the plasma. Current theories and simulations of double layers, which are one-dimensional, completely miss these critically important two-dimensional features.

Particle Heating in Space and Laboratory Plasmas

NASA Astrophysics Data System (ADS)

Scime, E. E.; Keesee, A. M.; Aquirre, E.; Good, T.

2017-12-01

We report spatially resolved perpendicular and parallel ion velocity distribution function (IVDF) measurements in an expanding argon helicon plasma. The parallel IVDFs, obtained through laser induced fluorescence (LIF), show an ion beam with v ˜ 8 km/s flowing downstream that is confined to the center of the discharge. The ion beam is confined to within a few centimeters radially and is measurable for tens of centimeters axially before the LIF signal fades, likely a result of metastable quenching of the beam ions. The axial ion beam velocity slows in agreement with collisional processes. The perpendicular IVDFs show an ion population with a radially outward flow that increases with radial location. The DC electric field, electron temperature, and the plasma density in the double layer plume are all consistent with magnetic field aligned structures. The upstream and downstream electric field measurements show clear evidence of an ion hole that maps along the magnetic field at the edge of the plasma. Current theories and simulations of double layers, which are one-dimensional, completely miss these critically important two-dimensional features.

Process parameter-growth environment-film property relationships for reactive sputter deposited metal (V, Nb, Zr, Y, Au) oxide, nitride, and oxynitride films. Final report, 1 January 1989-30 June 1993

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

Aita, C.R.

1993-09-30

The research developed process parameter-growth environment-film property relations (phase maps) for model sputter-deposited transition metal oxides, nitrides, and oxynitrides grown by reactive sputter deposition at low temperature. Optical emission spectrometry was used for plasma diagnostics. The results summarized here include the role of sputtered metal-oxygen molecular flux in oxide film growth; structural differences in highest valence oxides including conditions for amorphous growth; and using fundamental optical absorption edge features to probe short range structural disorder. Eight appendices containing sixteen journal articles are included.

Multimodality optical coherence tomography and fluorescence confocal scanning laser ophthalmoscopy in a zebrafish model of retinal vascular occlusion and remodeling

NASA Astrophysics Data System (ADS)

Li, Xiaoyue; Spitz, Kathleen; Bozic, Ivan; Tao, Yuankai K.

2018-02-01

Neovascularization in diabetic retinopathy (DR) and age-related macular degeneration (AMD) result in severe vision-loss and are two of the leading causes of blindness. The structural, metabolic, and vascular changes underlying retinal neovascularization are unknown and, thus, there is an unmet need to identify mechanisms of pathogenesis and novel anti-angiogenic therapies. Zebrafish is a robust ophthalmological model because its retina has comparable structure to the human retina and its fecundity and life-cycle enable development of mutant phenotypes of human pathologies. Here, we perform multimodal imaging with OCT and fluorescence confocal scanning laser ophthalmoscopy (cSLO) to identify changes in retinal structure and function in a zebrafish model of vascular leakage. Transgenic zebrafish with EGFP tagged plasma protein were imaged longitudinally at six time points over two weeks to visualize vascular perfusion changes from diethylaminobenzaldehyde (DEAB) treatment. Complementary contrast from OCT-A perfusion maps and cSLO imaging of plasma protein EGFP shows vascular occlusions posttreatment. cSLO images confirm presence of vessels despite loss of OCT-A signal. Plasma protein EGFP contrast also shows significant changes in vessel structure as compared to baseline images. OCT structural volumes show empty vessel cross-sections confirming non-perfusion. In addition, we present algorithms for automated biometric identification of OCT datasets using OCT-A vascular patterns in the presence of significant vascular perfusion changes. These results establish a framework for large-scale in vivo assays to identify novel anti-angiogenic compounds and understand the mechanisms ofneovascularization associated with retinal ocular pathologies.

Recovery of evolution of Grad-Shafranov equilibria from single-spacecraft data: Benchmarking and application to a flux transfer event

NASA Astrophysics Data System (ADS)

Sonnerup, B. U.; Hasegawa, H.; Nakamura, T.

2010-12-01

Even after the advent of multi-spacecraft missions such as Cluster and THEMIS, it has been difficult to distinguish between time evolution of, and spatial variation within, a space plasma structure on the basis of in situ measurements. We present a method for analyzing time evolution of two-dimensional (2D) and magnetohydrostatic, namely Grad-Shafranov equilibria, using data recorded by an observing probe as it traverses a quasi-static, 2D magnetic-field/plasma structure. The method recovers spatial initial values used in the classical Grad-Shafranov (GS) reconstruction [Sonnerup et al., JGR, 2006] for an interval before and after the time of actual measurements, by advancing them backward and forward in time based on a set of equation for an incompressible plasma; the consequence is generation of multiple GS maps or a movie of the 2D field structure. The method is successfully benchmarked by use of a 2D magnetohydrodynamic simulation of time-dependent magnetic reconnection, and then is applied to a magnetic flux transfer event (FTE) seen by Cluster at the dayside high-latitude magnetopause, which has been analyzed with the GS method [Hasegawa et al., Ann. Geophys., 2006]. The application shows that the field lines constituting the FTE flux rope were contracting toward its center as a result of modest convective flow in the region around the core of the flux rope.

Study of Large-Scale Wave Structure and Development of Equatorial Plasma Bubbles Using the C/NOFS Satellite

DTIC Science & Technology

2012-10-31

19241-FR-12-438 October 2012 3 Figure 1 . Two maps showing isodensity contours of the F layer, which were obtained with ALTAIR during the PSSR...REPORT DOCUMENTATION PAGE Form Approved OMB No. 0704-0188 Public reporting burden for this collection of information is estimated to average 1 ...currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. 1 . REPORT DATE (DD-MM-YYYY) 31-10-2012 2. REPORT TYPE

Mapping 3D plasma structure in the solar wind with the L1 constellation: joint observations from Wind, ACE, DSCOVR, and SoHO

NASA Astrophysics Data System (ADS)

Stevens, M. L.; Kasper, J. C.; Case, A. W.; Korreck, K. E.; Szabo, A.; Biesecker, D. A.; Prchlik, J.

2017-12-01

At this moment in time, four observatories with similar instrumentation- Wind, ACE, DSCOVR, and SoHO- are stationed directly upstream of the Earth and making continuous observations. They are separated by drift-time baselines of seconds to minutes, timescales on which MHD instabilities in the solar wind are known to grow and evolve, and spatial baselines of tens to 200 earth radii, length scales relevant to the Earth's magnetosphere. By comparing measurements of matched solar wind structures from the four vantage points, the form of structures and associated dynamics on these scales is illuminated. Our targets include shocks and MHD discontinuities, stream fronts, locii of reconnection and exhaust flow boundary layers, plasmoids, and solitary structures born of nonlinear instability. We use the tetrahedral quality factors and other conventions adopted for Cluster to identify periods where the WADS constellation is suitably non-degenerate and arranged in such a way as to enable specific types of spatial, temporal, or spatiotemporal inferences. We present here an overview of the geometries accessible to the L1 constellation and timing-based and plasma-based observations of solar wind structures from 2016-17. We discuss the unique potential of the constellation approach for space physics and space weather forecasting at 1 AU.

Detection of an electron beam in a high density plasma via an electrostatic probe

NASA Astrophysics Data System (ADS)

Majeski, Stephen; Yoo, Jongsoo; Zweben, Stewart; Yamada, Masaaki; Ji, Hantao

2017-10-01

The perturbation in floating potential by an electron beam is detected by a 1D floating potential probe array to evaluate the use of an electron beam for magnetic field line mapping in the Magnetic Reconnection Experiment (MRX) plasma. The MRX plasma is relatively high density (1013 cm-3) and low temperature (5 eV). Beam electrons are emitted from a tungsten filament and are accelerated by a 200 V potential across the sheath. They stream along the magnetic field lines towards the probe array. The spatial electron beam density profile is assumed to be a Gaussian along the radial axis of MRX and the effective beam width is determined from the radial profile of the floating potential. The magnitude of the perturbation is in agreement with theoretical predictions and the location of the perturbation is also in agreement with field line mapping. In addition, no significant broadening of the electron beam is observed after propagation for tens of centimeters through the high density plasma. These results demonstrate that this method of field line mapping is, in principle, feasible in high density plasmas. This work is supported by the DOE Contract No. DE-AC0209CH11466.

Talbot-Lau x-ray deflectometry phase-retrieval methods for electron density diagnostics in high-energy density experiments.

PubMed

Valdivia, Maria Pia; Stutman, Dan; Stoeckl, Christian; Mileham, Chad; Begishev, Ildar A; Bromage, Jake; Regan, Sean P

2018-01-10

Talbot-Lau x-ray interferometry uses incoherent x-ray sources to measure refraction index changes in matter. These measurements can provide accurate electron density mapping through phase retrieval. An adaptation of the interferometer has been developed in order to meet the specific requirements of high-energy density experiments. This adaptation is known as a moiré deflectometer, which allows for single-shot capabilities in the form of interferometric fringe patterns. The moiré x-ray deflectometry technique requires a set of object and reference images in order to provide electron density maps, which can be costly in the high-energy density environment. In particular, synthetic reference phase images obtained ex situ through a phase-scan procedure, can provide a feasible solution. To test this procedure, an object phase map was retrieved from a single-shot moiré image obtained from a plasma-produced x-ray source. A reference phase map was then obtained from phase-stepping measurements using a continuous x-ray tube source in a small laboratory setting. The two phase maps were used to retrieve an electron density map. A comparison of the moiré and phase-stepping phase-retrieval methods was performed to evaluate single-exposure plasma electron density mapping for high-energy density and other transient plasma experiments. It was found that a combination of phase-retrieval methods can deliver accurate refraction angle mapping. Once x-ray backlighter quality is optimized, the ex situ method is expected to deliver electron density mapping with improved resolution. The steps necessary for improved diagnostic performance are discussed.

Structure of chaotic magnetic field lines in IR-T1 tokamak due to ergodic magnetic limiter

NASA Astrophysics Data System (ADS)

Ahmadi, S.; Salar Elahi, A.; Ghorannevis, M.

2018-03-01

In this paper we have studied an Ergodic Magnetic Limiter (EML) based chaotic magnetic field for transport control in the edge plasma of IR-T1 tokamak. The resonance created by the EML causes perturbation of the equilibrium field line in tokamak and as a result, the field lines are chaotic in the vicinity of the dimerized island chains. Transport barriers are formed in the chaotic field line and actually observe in tokamak with reverse magnetic shear. We used area-preserving non-twist (and twist) Poincaré maps to describe the formation of transport barriers, which are actually features of Hamiltonian systems. This transport barrier is useful in reducing radial diffusion of the field line and thus improving the plasma confinement.

Lack of species-specific difference in pulmonary function when using mouse versus human plasma in a mouse model of hemorrhagic shock.

PubMed

Peng, Zhanglong; Pati, Shibani; Fontaine, Magali J; Hall, Kelly; Herrera, Anthony V; Kozar, Rosemary A

2016-11-01

Clinical studies have demonstrated that the early and empiric use of plasma improves survival after hemorrhagic shock. We have demonstrated in rodent models of hemorrhagic shock that resuscitation with plasma is protective to the lungs compared with lactated Ringer's solution. As our long-term objective is to determine the molecular mechanisms that modulate plasma's protective effects in injured bleeding patients, we have used human plasma in a mouse model of hemorrhagic shock. The goal of the current experiments is to determine if there are significant adverse effects on lung injury when using human versus mouse plasma in an established murine model of hemorrhagic shock and laparotomy. Mice underwent laparotomy and 90 minutes of hemorrhagic shock to a mean arterial pressure (MAP) of 35 ± 5 mm Hg followed by resuscitation at 1× shed blood using either mouse fresh frozen plasma (FFP), human FFP, or human lyophilized plasma. Mean arterial pressure was recorded during shock and for the first 30 minutes of resuscitation. After 3 hours, animals were killed, and lungs collected for analysis. There was a significant increase in early MAP when mouse FFP was used to resuscitate animals compared with human FFP or human lyophilized plasma. However, despite these differences, analysis of the mouse lungs revealed no significant differences in pulmonary histopathology, lung permeability, or lung edema between all three plasma groups. Analysis of neutrophil infiltration in the lungs revealed that mouse FFP decreased neutrophil influx as measured by neutrophil staining; however, myeloperoxidase immunostaining revealed no significant differences in between groups. The study of human plasma in a mouse model of hemorrhagic shock is feasible but does reveal some differences compared with mouse plasma-based resuscitation in physiologic measures such as MAP postresuscitation. Measures of end organ function such as lung injury appear to be comparable in this acute model of hemorrhagic shock and resuscitation.

Structure and dynamics of Ebola virus matrix protein VP40 by a coarse-grained Monte Carlo simulation

NASA Astrophysics Data System (ADS)

Pandey, Ras; Farmer, Barry

Ebola virus matrix protein VP40 (consisting of 326 residues) plays a critical role in viral assembly and its functions such as regulation of viral transcription, packaging, and budding of mature virions into the plasma membrane of infected cells. How does the protein VP40 go through structural evolution during the viral life cycle remains an open question? Using a coarse-grained Monte Carlo simulation we investigate the structural evolution of VP40 as a function of temperature with the input of a knowledge-based residue-residue interaction. A number local and global physical quantities (e.g. mobility profile, contact map, radius of gyration, structure factor) are analyzed with our large-scale simulations. Our preliminary data show that the structure of the protein evolves through different state with well-defined morphologies which can be identified and quantified via a detailed analysis of structure factor.

Performance of a Space-Based Wavelet Compressor for Plasma Count Data on the MMS Fast Plasma Investigation

NASA Technical Reports Server (NTRS)

Barrie, A. C.; Smith, S. E.; Dorelli, J. C.; Gershman, D. J.; Yeh, P.; Schiff, C.; Avanov, L. A.

2017-01-01

Data compression has been a staple of imaging instruments for years. Recently, plasma measurements have utilized compression with relatively low compression ratios. The Fast Plasma Investigation (FPI) on board the Magnetospheric Multiscale (MMS) mission generates data roughly 100 times faster than previous plasma instruments, requiring a higher compression ratio to fit within the telemetry allocation. This study investigates the performance of a space-based compression standard employing a Discrete Wavelet Transform and a Bit Plane Encoder (DWT/BPE) in compressing FPI plasma count data. Data from the first 6 months of FPI operation are analyzed to explore the error modes evident in the data and how to adapt to them. While approximately half of the Dual Electron Spectrometer (DES) maps had some level of loss, it was found that there is little effect on the plasma moments and that errors present in individual sky maps are typically minor. The majority of Dual Ion Spectrometer burst sky maps compressed in a lossless fashion, with no error introduced during compression. Because of induced compression error, the size limit for DES burst images has been increased for Phase 1B. Additionally, it was found that the floating point compression mode yielded better results when images have significant compression error, leading to floating point mode being used for the fast survey mode of operation for Phase 1B. Despite the suggested tweaks, it was found that wavelet-based compression, and a DWT/BPE algorithm in particular, is highly suitable to data compression for plasma measurement instruments and can be recommended for future missions.

Review: engineering particles using the aerosol-through-plasma method

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

Phillips, Jonathan; Luhrs, Claudia C; Richard, Monique

2009-01-01

For decades, plasma processing of materials on the nanoscale has been an underlying enabling technology for many 'planar' technologies, particularly virtually every aspect of modern electronics from integrated-circuit fabrication with nanoscale elements to the newest generation of photovoltaics. However, it is only recent developments that suggest that plasma processing can be used to make 'particulate' structures of value in fields, including catalysis, drug delivery, imaging, higher energy density batteries, and other forms of energy storage. In this paper, the development of the science and technology of one class of plasma production of particulates, namely, aerosol-through-plasma (A-T-P), is reviewed. Various plasmamore » systems, particularly RF and microwave, have been used to create nanoparticles of metals and ceramics, as well as supported metal catalysts. Gradually, the complexity of the nanoparticles, and concomitantly their potential value, has increased. First, unique two-layer particles were generated. These were postprocessed to create unique three-layer nanoscale particles. Also, the technique has been successfully employed to make other high-value materials, including carbon nanotubes, unsupported graphene, and spherical boron nitride. Some interesting plasma science has also emerged from efforts to characterize and map aerosol-containing plasmas. For example, it is clear that even a very low concentration of particles dramatically changes plasma characteristics. Some have also argued that the local-thermodynamic-equilibrium approach is inappropriate to these systems. Instead, it has been suggested that charged- and neutral-species models must be independently developed and allowed to 'interact' only in generation terms.« less

Local turbulence simulations for the multiphase ISM

NASA Astrophysics Data System (ADS)

Kissmann, R.; Kleimann, J.; Fichtner, H.; Grauer, R.

2008-12-01

In this paper, we show results of numerical simulations for the turbulence in the interstellar medium (ISM). These results were obtained using a Riemann solver-free numerical scheme for high-Mach number hyperbolic equations. Here, we especially concentrate on the physical properties of the ISM. That is, we do not present turbulence simulations trimmed to be applicable to the ISM. The simulations are rather based on physical estimates for the relevant parameters of the interstellar gas. Applying our code to simulate the turbulent plasma motion within a typical interstellar molecular cloud, we investigate the influence of different equations of state (isothermal and adiabatic) on the statistical properties of the resulting turbulent structures. We find slightly different density power spectra and dispersion maps, while both cases yield qualitatively similar dissipative structures, and exhibit a departure from the classical Kolmogorov case towards a scaling described by the She-Leveque model. Solving the full energy equation with realistic heating/cooling terms appropriate for the diffuse interstellar gas (DIG), we are able to reproduce a realistic two-phase distribution of cold and warm plasma. When extracting maps of polarized intensity from our simulation data, we find encouraging similarity to actual observations. Finally, we compare the actual magnetic field strength of our simulations to its value inferred from the rotation measure. We find these to be systematically different by a factor of about 1.15, thus highlighting the often-underestimated influence of varying line-of-sight particle densities on the magnetic field strength derived from observed rotation measures.

Global mapping of rat plasma proteins with a native proteomic approach using nondenaturing micro 2DE and quantitative LC-MS/MS.

PubMed

Chen, Shumin; Wen, Meiling; Bu, Shujie; Wang, Ahui; Jin, Ya; Tan, Wen

2016-12-01

Plasma samples from adult male rats were separated by nondenaturing micro 2DE and a reference gel was selected, on which 136 CBB-stained spots were numbered and subjected to in-gel digestion and quantitative LC-MS/MS. The analysis provided the assignment of 1-25 (average eight) non-redundant proteins in each spot and totally 199 proteins were assigned in the 136 spots. About 40% of the proteins were detected in more than one spot and 15% in more than ten spots. We speculate this complexity arose from multiple causes, including protein heterogeneity, overlapping of protein locations and formation of protein complexes. Consequently, such results could not be appropriately presented as a conventional 2DE map, i.e. a list or a gel pattern with one or a few proteins annotated to each spot. Therefore, the LC-MS/MS quantity data was used to reconstruct the gel distribution of each protein and a library containing 199 native protein maps was established for rat plasma. Since proteins that formed a complex would migrate together during the nondenaturing 2DE and thus show similar gel distributions, correlation analysis was attempted for similarity comparison between the maps. The protein pairs showing high correlation coefficients included some well-known complexes, suggesting the promising application of native protein mapping for interaction analysis. With the importance of rat as the most commonly used laboratory animal in biomedical research, we expect this work would facilitate relevant studies by providing not only a reference library of rat plasma protein maps but a means for functional and interaction analysis. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Problems with mapping the auroral oval and magnetospheric substorms

NASA Astrophysics Data System (ADS)

Antonova, E. E.; Vorobjev, V. G.; Kirpichev, I. P.; Yagodkina, O. I.; Stepanova, M. V.

2015-10-01

Accurate mapping of the auroral oval into the equatorial plane is critical for the analysis of aurora and substorm dynamics. Comparison of ion pressure values measured at low altitudes by Defense Meteorological Satellite Program (DMSP) satellites during their crossings of the auroral oval, with plasma pressure values obtained at the equatorial plane from Time History of Events and Macroscale Interactions during Substorms (THEMIS) satellite measurements, indicates that the main part of the auroral oval maps into the equatorial plane at distances between 6 and 12 Earth radii. On the nightside, this region is generally considered to be a part of the plasma sheet. However, our studies suggest that this region could form part of the plasma ring surrounding the Earth. We discuss the possibility of using the results found here to explain the ring-like shape of the auroral oval, the location of the injection boundary inside the magnetosphere near the geostationary orbit, presence of quiet auroral arcs in the auroral oval despite the constantly high level of turbulence observed in the plasma sheet, and some features of the onset of substorm expansion.

Problems with mapping the auroral oval and magnetospheric substorms.

PubMed

Antonova, E E; Vorobjev, V G; Kirpichev, I P; Yagodkina, O I; Stepanova, M V

Accurate mapping of the auroral oval into the equatorial plane is critical for the analysis of aurora and substorm dynamics. Comparison of ion pressure values measured at low altitudes by Defense Meteorological Satellite Program (DMSP) satellites during their crossings of the auroral oval, with plasma pressure values obtained at the equatorial plane from Time History of Events and Macroscale Interactions during Substorms (THEMIS) satellite measurements, indicates that the main part of the auroral oval maps into the equatorial plane at distances between 6 and 12 Earth radii. On the nightside, this region is generally considered to be a part of the plasma sheet. However, our studies suggest that this region could form part of the plasma ring surrounding the Earth. We discuss the possibility of using the results found here to explain the ring-like shape of the auroral oval, the location of the injection boundary inside the magnetosphere near the geostationary orbit, presence of quiet auroral arcs in the auroral oval despite the constantly high level of turbulence observed in the plasma sheet, and some features of the onset of substorm expansion.

Meat juice: An alternative matrix for assessing animal health by measuring acute phase proteins. Correlations of pig-MAP and haptoglobin concentrations in pig meat juice and plasma.

PubMed

Piñeiro, M; Gymnich, S; Knura, S; Piñeiro, C; Petersen, B

2009-10-01

Quantification of acute phase proteins (APPs) in blood can be used for monitoring animal health and welfare on farms, and could be also of interest for the detection of diseased animals during the meat inspection process. However serum or plasma is not always available for end-point analysis at slaughter. Meat juice might provide an adequate, alternative matrix that can be easily obtained for post-mortem analysis at abattoirs. The concentrations of pig Major Acute phase Protein (pig-MAP) and haptoglobin, two of the main APPs in pigs, were determined in approximately 300 paired samples of plasma and meat juice from the diaphragm (pars costalis), obtained after freezing and thawing the muscle. APPs concentrations in meat juice were closely correlated to those in plasma (r=0.695 for haptoglobin, r=0.858 for pig-MAP, p<0.001). These results open new possibilities for the assessment of animal health in pig production, with implications for food safety and meat quality.

Proteomic analysis of plasma-purified VLDL, LDL, and HDL fractions from atherosclerotic patients undergoing carotid endarterectomy: identification of serum amyloid A as a potential marker.

PubMed

Lepedda, Antonio J; Nieddu, Gabriele; Zinellu, Elisabetta; De Muro, Pierina; Piredda, Franco; Guarino, Anna; Spirito, Rita; Carta, Franco; Turrini, Francesco; Formato, Marilena

2013-01-01

Apolipoproteins are very heterogeneous protein family, implicated in plasma lipoprotein structural stabilization, lipid metabolism, inflammation, or immunity. Obtaining detailed information on apolipoprotein composition and structure may contribute to elucidating lipoprotein roles in atherogenesis and to developing new therapeutic strategies for the treatment of lipoprotein-associated disorders. This study aimed at developing a comprehensive method for characterizing the apolipoprotein component of plasma VLDL, LDL, and HDL fractions from patients undergoing carotid endarterectomy, by means of two-dimensional electrophoresis (2-DE) coupled with Mass Spectrometry analysis, useful for identifying potential markers of plaque presence and vulnerability. The adopted method allowed obtaining reproducible 2-DE maps of exchangeable apolipoproteins from VLDL, LDL, and HDL. Twenty-three protein isoforms were identified by peptide mass fingerprinting analysis. Differential proteomic analysis allowed for identifying increased levels of acute-phase serum amyloid A protein (AP SAA) in all lipoprotein fractions, especially in LDL from atherosclerotic patients. Results have been confirmed by western blotting analysis on each lipoprotein fraction using apo AI levels for data normalization. The higher levels of AP SAA found in patients suggest a role of LDL as AP SAA carrier into the subendothelial space of artery wall, where AP SAA accumulates and may exert noxious effects.

Arterial and venous plasma levels of bupivacaine following peripheral nerve blocks.

PubMed

Moore, D C; Mather, L E; Bridenbaugh, L D; Balfour, R I; Lysons, D F; Horton, W G

1976-01-01

Mean arterial plasma (MAP) and peripheral mean venous plasma (MVP) levels of bupivacaine were ascertained in 3 groups of 10 patients each for: (1) intercostal nerve block, 400 mg; (2) block of the sciatic, femoral, and lateral femoral cutaneous nerves, with or without block of the obturator nerve, 400 mg; and (3) supraclavicular brachial plexus block, 300 mg. MAP levels were consistently higher than simultaneously sampled MVP levels, the highest levels occurring from bilateral intercostal nerve block. No evidence of systemic toxicity was observed. The results suggest that bupivacaine has a much wider margin of safety in humans than is now stated.

Coherent structures and turbulence evolution in magnetized non-neutral plasmas

NASA Astrophysics Data System (ADS)

Romé, M.; Chen, S.; Maero, G.

2018-01-01

The evolution of turbulence of a magnetized pure electron plasma confined in a Penning-Malmberg trap is investigated by means of a two-dimensional particle-in-cell numerical code. The transverse plasma dynamics is studied both in the case of free evolution and under the influence of non-axisymmetric, multipolar radio-frequency drives applied on the circular conducting boundary. In the latter case the radio-frequency fields are chosen in the frequency range of the low-order azimuthal (diocotron) modes of the plasma in order to investigate their effect on the insurgence of azimuthal instabilities and the formation and evolution of coherent structures, possibly preventing the relaxation to a fully-developed turbulent state. Different initial density distributions (rings and spirals) are considered, so that evolutions characterized by different levels of turbulence and intermittency are obtained. The time evolution of integral and spectral quantities of interest are computed using a multiresolution analysis based on a wavelet decomposition of density maps. Qualitative features of turbulent relaxation are found to be similar in conditions of both free and forced evolution, but the analysis allows one to highlight fine details of the flow beyond the self-similarity turbulence properties, so that the influence of the initial conditions and the effect of the external forcing can be distinguished. In particular, the presence of small inhomogeneities in the initial density configuration turns out to lead to quite different final states, especially in the presence of competing unstable diocotron modes characterized by similar growth rates.

Understanding the Chaotic Behavior of Field Lines using the Simple Map

NASA Astrophysics Data System (ADS)

Saralkar, R.; White, C.; Ali, H.; Punjabi, A.

1998-11-01

The Simple Map is given by x_n+1=x_n-ky_n(1-y_n), y_n+1=y_n+kx_n+1. Different initial values of x and y create different surfaces. We can see at what point the order begins to fade, at what point the surface breaks up and islands form, and at what point chaos occurs. The outer surfaces are chaotic as expected because the plasma is nearing the X-point in the tokamak, where the order begins to break up. We are specifically investigating two areas of the Simple Map. First we want to see what ther surfaces look like if they are magnified near the X-point. We are looking for self-similar structures in which order can be found in chaos, and chaos can be found in order. Our second investigation deals with how neighboring field lines separate in the chaotic region. We are expecting to see the distance between two close points drastically increase as we near the X-point. Reshama Saralkar and Cedric White are HU CFRT 1998 Summer Fusion High School Workshop Participants from the NASA SHARP PLUS Program. RS attends Watkins Mill High School in Gaithersburg, MD. CW attends Gwynn Park High School in Brandywine,MD. They are mentored by Dr. Ali and Dr. Punjabi of HU CFRT. 1. Punjabi et al, Phys Rev Lett 69 3322 (1992) 2. Punjabi et al, J Plasma Phys 52 91 (1994)

The ameliorating effects of long-term electroacupuncture on cardiovascular remodeling in spontaneously hypertensive rats.

PubMed

Huo, Ze-Jun; Li, Quan; Tian, Gui-Hua; Zhou, Chang-Man; Wei, Xiao-Hong; Pan, Chun-Shui; Yang, Lei; Bai, Yan; Zhang, You-Yi; He, Ke; Wang, Chuan-She; Li, Zhi-Gang; Han, Jing-Yan

2014-04-01

The purpose of this study was to investigate the inhibitory effects of long-term electroacupuncture at BaiHui (DU20) and ZuSanLi (ST36) on cardiovascular remodeling in spontaneously hypertensive rats (SHR) and underlying mechanisms. 6-weeks-old SHR or Wistar male rats were randomly, divided into 6 groups: the control group (SHR/Wistar), the non-acupoint electroacupuncture stimulation group (SHR-NAP/Wistar-NAP) and the electroacupuncture stimulation at DU20 and ST36 group (SHR-AP/Wistar-AP), 24 rats in each group. Rats were treated with or without electroacupuncture at DU20 and ST36, once every other day for a period of 8 weeks. The mean arterial pressure (MAP) was measured once every 2 weeks. By the end of the 8th week, the left ventricular structure and function were assessed by echocardiography. The content of angiotensin II (Ang II), endothelin-1 (ET-1) and nitric oxide (NO) in the plasma was determined using enzyme-linked immunosorbent assay. Histological studies on the heart and the ascending aorta were performed. The expression of angiotensin II type 1 receptor (AT1R), endothelin-1 type A receptor (ETAR), eNOS and iNOS in rat myocardium and ascending aorta was investigated by Western blotting. The MAP in SHR increased linearly over the observation period and significantly reduced following electroacupuncture as compared with sham control SHR rats, while no difference in MAP was observed in Wistar rats between electroacupuncture and sham control. The aortic wall thickness, cardiac hypertrophy and increased collagen level in SHR were attenuated by long term electroacupuncture. The content of Ang II, ET-1 in the plasma decreased, but the content of NO increased after electroacupuncture stimulation in SHR. Long term electroacupuncture significantly inhibited the expression of AT1R, ETAR and iNOS, whereas increased eNOS expression, in myocardium and ascending aorta of SHR. The long term electroacupuncture stimulation at DU20 and ST36 relieves the increased MAP and cardiovascular abnormality in both structure and function in SHR, this beneficial action is most likely mediated via modulation of AT1R-AT1R-ET-1-ETAR and NOS/NO pathway.

Properties of large electric fields in the plasma sheet at 4-7RE measured with Polar

NASA Astrophysics Data System (ADS)

Keiling, A.; Wygant, J. R.; Cattell, C.; Johnson, M.; Temerin, M.; Mozer, F. S.; Kletzing, C. A.; Scudder, J.; Russell, C. T.

2001-04-01

Measurements from the Polar satellite provide evidence for large electric field structures in the plasma sheet at geocentric distances of 4-7RE. These structures had amplitudes perpendicular to the ambient magnetic field that can exceed 100 mV m-1 (6 s averaged). Two years (from May 1, 1996, to April 30, 1998) of electric field data (EZ component, approximately along GSE z) were surveyed. The distribution in invariant latitude (ILAT) and magnetic local time (MLT) of large perpendicular electric field events (defined as >=20 mV m-1 for a 6-s average) delineates the statistical auroral oval with the majority of events occurring in the nightside centered around midnight and a smaller concentration around 1500 MLT. The magnitude-versus-altitude distribution of the electric fields between 4 and 7RE in the nightside could be explained by models which assume either shear Alfvén waves propagating into regions of larger background magnetic fields or electrostatic structures being mapped quasi-statically along equipotential magnetic field lines. In addition, this survey yielded 24 very large amplitude events with |E⊥|>=100mVm-1 (6 s averaged), all of which occurred in the nightside. In the spacecraft frame, the electric field structures occurred on timescales ranging from 10 to 60 s. About 85% of these events occurred in the vicinity of the outer boundary of the plasma sheet; the rest occurred in the central plasma sheet. The polarity of the electric fields was dominantly perpendicular to the nominal plasma sheet boundary. For a large fraction of events (<=50%) the ratios of electric and magnetic fields in the period range from 10 to 60 s were consistent with Alfvén waves. Large Poynting flux (up to 2.5 ergs cm-2s-1) dominantly directed downward along the background magnetic field was associated with 21 events. All 24 events occurred during geomagnetic disturbances such as magnetic substorms. A conjugate study with ground stations for 14 events (out of the 24 events) showed that these structures occurred during times of rapid changes in the H component (or X component) of magnetometer data. For most events this time corresponded to the expansion phase; two events occurred during a quick recovery of the negative H bay signature. Thus there is evidence that large electromagnetic energy transfer processes in the plasma sheet occur during the most dynamic phase of geomagnetic disturbances. From the statistical analysis it was found that Polar observed events larger than 100 mV m-1 (50 mV m-1) in the plasma sheet between 2100 and 0300 MLT with a 2-4% (15%) probability per crossing. These probabilities will be compared to the probability of substorm occurrence during Polar plasma sheet crossings.

Electro-optic spatial decoding on the spherical-wavefront Coulomb fields of plasma electron sources.

PubMed

Huang, K; Esirkepov, T; Koga, J K; Kotaki, H; Mori, M; Hayashi, Y; Nakanii, N; Bulanov, S V; Kando, M

2018-02-13

Detections of the pulse durations and arrival timings of relativistic electron beams are important issues in accelerator physics. Electro-optic diagnostics on the Coulomb fields of electron beams have the advantages of single shot and non-destructive characteristics. We present a study of introducing the electro-optic spatial decoding technique to laser wakefield acceleration. By placing an electro-optic crystal very close to a gas target, we discovered that the Coulomb field of the electron beam possessed a spherical wavefront and was inconsistent with the previously widely used model. The field structure was demonstrated by experimental measurement, analytic calculations and simulations. A temporal mapping relationship with generality was derived in a geometry where the signals had spherical wavefronts. This study could be helpful for the applications of electro-optic diagnostics in laser plasma acceleration experiments.

Localization of Filipin-Sterol Complexes in the Membranes of Beta vulgaris Roots and Spinacia oleracea Chloroplasts 1

PubMed Central

Moeller, Curt H.; Mudd, J. Brian

1982-01-01

Filipin was used as a cytochemical probe for membrane sterols in the root storage tissue of the red beet Beta vulgaris L. and the chloroplasts of Spinacia oleracea L. In unfixed beet tissue, filipin lysed the cells. Freeze-fracture replicas revealed that the filipin-sterol complexes were tightly aggregated in the plasma membrane, while in thin section the complexes corrugated the plasma membrane. If the cells were fixed with glutaraldehyde prior to the filipin treatment, the cell structure was preserved. Filipin-induced lesions were dispersed or clustered loosely in the plasma membrane. A few filipin-sterol complexes were observed in the tonoplast. In spinach chloroplasts, filipin-sterol complexes were limited to the outer membrane of the envelope and were not found in the inner membrane of the envelope or in the lamellar membranes. If the filipin-sterol complexes accurately mapped the distribution of membrane sterols, then sterol was located predominantly in the plasma membrane of the red beet and in the outer membrane of the chloroplast envelope. Furthermore, the sterol may be heterogenously distributed laterally in both these membranes. Images Fig. 2 Fig. 3 Fig. 4 Fig. 5 PMID:16662716

Observational Evidence of a Flux Rope within a Sunspot Umbra

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

Guglielmino, Salvo L.; Zuccarello, Francesca; Romano, Paolo, E-mail: salvo.guglielmino@oact.inaf.it

We observed an elongated filamentary bright structure inside the umbra of the big sunspot in active region NOAA 12529, which differs from the light bridges usually observed in sunspots for its morphology, magnetic configuration, and velocity field. We used observations taken with the Solar Dynamic Observatory satellite to characterize this feature. Its lifetime is 5 days, during which it reaches a maximum length of about 30″. In the maps of the vertical component of the photospheric magnetic field, a portion of the feature has a polarity opposite to that of the hosting sunspot. At the same time, in the entiremore » feature the horizontal component of the magnetic field is about 2000 G, substantially stronger than in the surrounding penumbral filaments. Doppler velocity maps reveal the presence of both upward and downward plasma motions along the structure at the photospheric level. Moreover, looking at the chromospheric level, we noted that it is located in a region corresponding to the edge of a small filament that seems rooted in the sunspot umbra. Therefore, we interpreted the bright structure as the photospheric counterpart of a flux rope touching the sunspot and giving rise to penumbral-like filaments in the umbra.« less

Comprehensive process maps for synthesizing high density aluminum oxide-carbon nanotube coatings by plasma spraying for improved mechanical and wear properties

NASA Astrophysics Data System (ADS)

Keshri, Anup Kumar

Plasma sprayed aluminum oxide ceramic coating is widely used due to its outstanding wear, corrosion, and thermal shock resistance. But porosity is the integral feature in the plasma sprayed coating which exponentially degrades its properties. In this study, process maps were developed to obtain Al2O3-CNT composite coatings with the highest density (i.e. lowest porosity) and improved mechanical and wear properties. Process map is defined as a set of relationships that correlates large number of plasma processing parameters to the coating properties. Carbon nanotubes (CNTs) were added as reinforcement to Al2O 3 coating to improve the fracture toughness and wear resistance. Two novel powder processing approaches viz spray drying and chemical vapor growth were adopted to disperse CNTs in Al2O3 powder. The degree of CNT dispersion via chemical vapor deposition (CVD) was superior to spray drying but CVD could not synthesize powder in large amount. Hence optimization of plasma processing parameters and process map development was limited to spray dried Al2O3 powder containing 0, 4 and 8 wt. % CNTs. An empirical model using Pareto diagram was developed to link plasma processing parameters with the porosity of coating. Splat morphology as a function of plasma processing parameter was also studied to understand its effect on mechanical properties. Addition of a mere 1.5 wt. % CNTs via CVD technique showed ˜27% and ˜24% increase in the elastic modulus and fracture toughness respectively. Improved toughness was attributed to combined effect of lower porosity and uniform dispersion of CNTs which promoted the toughening by CNT bridging, crack deflection and strong CNT/Al2O3 interface. Al2O 3-8 wt. % CNT coating synthesized using spray dried powder showed 73% improvement in the fracture toughness when porosity reduced from 4.7% to 3.0%. Wear resistance of all coatings at room and elevated temperatures (573 K, 873 K) showed improvement with CNT addition and decreased porosity. Such behavior was due to improved mechanical properties, protective film formation due to tribochemical reaction, and CNT bridging between the splats. Finally, process maps correlating porosity content, CNT content, mechanical properties, and wear properties were developed.

The giraffe kidney tolerates high arterial blood pressure by high renal interstitial pressure and low glomerular filtration rate.

PubMed

Damkjaer, M; Wang, T; Brøndum, E; Østergaard, K H; Baandrup, U; Hørlyck, A; Hasenkam, J M; Smerup, M; Funder, J; Marcussen, N; Danielsen, C C; Bertelsen, M F; Grøndahl, C; Pedersen, M; Agger, P; Candy, G; Aalkjaer, C; Bie, P

2015-08-01

The tallest animal on earth, the giraffe (Giraffa camelopardalis) is endowed with a mean arterial blood pressure (MAP) twice that of other mammals. The kidneys reside at heart level and show no sign of hypertension-related damage. We hypothesized that a species-specific evolutionary adaption in the giraffe kidney allows normal for size renal haemodynamics and glomerular filtration rate (GFR) despite a MAP double that of other mammals. Fourteen anaesthetized giraffes were instrumented with vascular and bladder catheters to measure glomerular filtration rate (GFR) and effective renal plasma flow (ERPF). Renal interstitial hydrostatic pressure (RIHP) was assessed by inserting a needle into the medullary parenchyma. Doppler ultrasound measurements provided renal artery resistive index (RI). Hormone concentrations as well as biomechanical, structural and histological characteristics of vascular and renal tissues were determined. GFR averaged 342 ± 99 mL min(-1) and ERPF 1252 ± 305 mL min(-1) . RIHP varied between 45 and 140 mmHg. Renal pelvic pressure was 39 ± 2 mmHg and renal venous pressure 32 ± 4 mmHg. A valve-like structure at the junction of the renal and vena cava generated a pressure drop of 12 ± 2 mmHg. RI was 0.27. The renal capsule was durable with a calculated burst pressure of 600 mmHg. Plasma renin and AngII were 2.6 ± 0.5 mIU L(-1) and 9.1 ± 1.5 pg mL(-1) respectively. In giraffes, GFR, ERPF and RI appear much lower than expected based on body mass. A strong renal capsule supports a RIHP, which is >10-fold that of other mammals effectively reducing the net filtration pressure and protecting against the high MAP. © 2015 Scandinavian Physiological Society. Published by John Wiley & Sons Ltd.

Microscopy of Alloy Formation on Arc Plasma Sintered Oxide Dispersion Strengthen (ODS) Steel

NASA Astrophysics Data System (ADS)

Bandriyana, B.; Sujatno, A.; Salam, R.; Dimyati, A.; Untoro, P.

2017-07-01

The oxide dispersed strengthened (ODS) alloys steel developed as structure material for nuclear power plants (NPP) has good resistant against creep due to their unique microstructure. Microscopy investigation on the microstructure formation during alloying process especially at the early stages was carried out to study the correlation between structure and property of ODS alloys. This was possible thanks to the arc plasma sintering (APS) device which can simulate the time dependent alloying processes. The ODS sample with composition of 88 wt.% Fe and 12 wt.% Cr powder dispersed with 1 wt.% ZrO2 nano powder was mixed in a high energy milling, isostatic compressed to form sample coins and then alloyed in APS. The Scanning Electron Microscope (SEM) with X-ray Diffraction Spectroscopy (EDX) line scan and mapping was used to characterize the microstructure and elemental composition distribution of the samples. The alloying process with unification of each Fe and Cr phase continued by the alloying formation of Fe-Cr by inter-diffusion of both Fe and Cr and followed by the improvement of the mechanical properties of hardness.

Recovery of time evolution of Grad-Shafranov equilibria from single-spacecraft data: Benchmarking and application to a flux transfer event

NASA Astrophysics Data System (ADS)

Hasegawa, Hiroshi; Sonnerup, Bengt U. Ã.-.; Nakamura, Takuma K. M.

2010-11-01

First results are presented of a method, developed by Sonnerup and Hasegawa (2010), for analyzing time evolution of magnetohydrostatic Grad-Shafranov (GS) equilibria, using data recorded by an observing probe as it traverses a quasi-static, two-dimensional (2D), magnetic-field/plasma structure. The method recovers spatial initial values used in the classical GS reconstruction for an interval before and after the time of actual measurements, by advancing them backward and forward in time based on a set of equations for an incompressible plasma; the consequence is generation of multiple GS maps or a movie of the 2D field structure. The method is successfully benchmarked by use of a 2D magnetohydrodynamic simulation of time-dependent magnetic reconnection, and then is applied to a flux transfer event (FTE) seen by the Cluster spacecraft at the dayside high-latitude magnetopause. The application shows that the field lines constituting the FTE flux rope were contracting toward its center as a result of modest convective flow in the region around the core of the flux rope.

Effects of shear on the magnetic footprint and stochastic layer in double-null divertor tokamak

NASA Astrophysics Data System (ADS)

Farhat, Hamidullah; Punjabi, Alkesh; Ali, Halima

2006-10-01

We have developed a new area-preserving map, called the Adjustable Shear Map, to calculate effects of shear on the magnetic footprint and stochastic layer in double-null divertor tokamak. The map is given by equationsxn+1=xn-kyn[(1-yn^2 )(1+syn)+sxn+1^2 ),yn+1=yn+kxn+1[1+s(xn+1^2 +yn^2 )]. k is the map parameter and s is the shear parameter. O-point of the map is (0, 0), and the X-points are (0, 1), and (0, -1). For s=0, k=0.6, the last good surface is y=0.9918 with q ˜3. Here we will report on the effects of shear on the stochastic layer and magnetic footprint as the shear parameter is varied from 0 to -1. Here we will report the preliminary results on the effect of shear on the magnetic foot print and the stochastic layer where the shear parameter s has values between -1 and 0. using method of maps [1-4]. This work is done under the DOE grant number DE-FG02-01ER54624. 1. A. Punjabi, A. Boozer, and A. Verma, Phys. Rev. lett., 69, 3322 (1992). 2. H. Ali, A. Punjabi, and A. Boozer, Phys. Plasmas 11, 4527 (2004). 3. A. Punjabi, H. Ali, and A. Boozer, Phys. Plasmas 10, 3992 (2003). 4. A. Punjabi, H. Ali, and A. Boozer, Phys. Plasmas 4, 337 (1997).

High-resolution measurements of the spatial and temporal evolution of megagauss magnetic fields created in intense short-pulse laser-plasma interactions

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

Chatterjee, Gourab, E-mail: gourab@tifr.res.in; Singh, Prashant Kumar; Adak, Amitava

A pump-probe polarimetric technique is demonstrated, which provides a complete, temporally and spatially resolved mapping of the megagauss magnetic fields generated in intense short-pulse laser-plasma interactions. A normally incident time-delayed probe pulse reflected from its critical surface undergoes a change in its ellipticity according to the magneto-optic Cotton-Mouton effect due to the azimuthal nature of the ambient self-generated megagauss magnetic fields. The temporal resolution of the magnetic field mapping is typically of the order of the pulsewidth, limited by the laser intensity contrast, whereas a spatial resolution of a few μm is achieved by this optical technique. High-harmonics of themore » probe can be employed to penetrate deeper into the plasma to even near-solid densities. The spatial and temporal evolution of the megagauss magnetic fields at the target front as well as at the target rear are presented. The μm-scale resolution of the magnetic field mapping provides valuable information on the filamentary instabilities at the target front, whereas probing the target rear mirrors the highly complex fast electron transport in intense laser-plasma interactions.« less

Pressure-dependent changes in haematocrit and plasma volume during anaesthesia, a randomised clinical trial.

PubMed

Damén, T; Reinsfelt, B; Redfors, B; Nygren, A

2016-05-01

Induction of general anaesthesia has been shown to cause haemodilution and an increase in plasma volume. The aim of this study was to evaluate whether prevention of hypotension during anaesthesia induction could avoid haemodilution. Twenty-four cardiac surgery patients, 66 ± 10 years, were randomised to receive either norepinephrine in a dose needed to maintain mean arterial blood pressure (MAP) at pre-anaesthesia levels after induction or to a control group that received vasopressor if MAP decreased below 60 mmHg. No fluids were infused. Changes in plasma volume were calculated with standard formula: 100 × (Hct(pre)/Hct(post) - 1)/(1 - Hct(pre)). Arterial blood gas was analysed every 10 minutes and non-invasive continuous haemoglobin (SpHb) was continuously measured. Pre-anaesthesia MAP was 98 ± 7 mmHg. Ten minutes after anaesthesia induction, the haematocrit decreased by 5.0 ± 2.5% in the control group compared with 1.2 ± 1.4% in the intervention group, which corresponds to increases in plasma volume by 310 ml and 85 ml respectively. MAP decreased to 69 ± 15 mmHg compared to 92 ± 10 mmHg in the intervention group. The difference maintained throughout the 70 min intervention period. The change in haemoglobin level measured by blood gas analysis could not be detected by SpHb measurement. The mean bias between the SpHb and blood gas haemoglobin was 15 g/l. During anaesthesia induction, haematocrit decreases and plasma volume increases early and parallel to a decrease in blood pressure. This autotransfusion is blunted when blood pressure is maintained at pre-induction levels with norepinephrine. © 2016 The Acta Anaesthesiologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

Mapping the pharmaceutical design space by amorphous ionic liquid strategies.

PubMed

Wiest, Johannes; Saedtler, Marco; Balk, Anja; Merget, Benjamin; Widmer, Toni; Bruhn, Heike; Raccuglia, Marc; Walid, Elbast; Picard, Franck; Stopper, Helga; Dekant, Wolfgang; Lühmann, Tessa; Sotriffer, Christoph; Galli, Bruno; Holzgrabe, Ulrike; Meinel, Lorenz

2017-12-28

Poor water solubility of drugs fuels complex formulations and jeopardizes patient access to medication. Simplifying these complexities we systematically synthesized a library of 36 sterically demanding counterions and mapped the pharmaceutical design space for amorphous ionic liquid strategies for Selurampanel, a poorly water soluble drug used against migraine. Patients would benefit from a rapid uptake after oral administration to alleviate migraine symptoms. Therefore, we probed the ionic liquids for the flux, supersaturation period and hygroscopicity leading to algorithms linking molecular counterion descriptors to predicted pharmaceutical outcome. By that, 30- or 800-fold improvements of the supersaturation period and fluxes were achieved as were immediate to sustained release profiles through structural counterions' optimization compared to the crystalline free acid of Selurampanel. Guided by ionic liquid structure, in vivo profiles ranged from rapid bioavailability and high maximal plasma concentrations to sustained patterns. In conclusion, the study outlined and predicted the accessible pharmaceutical design space of amorphous ionic liquid based and excipient-free formulations pointing to the enormous pharmaceutical potential of ionic liquid designs. Copyright © 2017 Elsevier B.V. All rights reserved.

Enhancing in vivo tumor boundary delineation with structured illumination fluorescence molecular imaging and spatial gradient mapping

NASA Astrophysics Data System (ADS)

Sun, Jessica; Miller, Jessica P.; Hathi, Deep; Zhou, Haiying; Achilefu, Samuel; Shokeen, Monica; Akers, Walter J.

2016-08-01

Fluorescence imaging, in combination with tumor-avid near-infrared (NIR) fluorescent molecular probes, provides high specificity and sensitivity for cancer detection in preclinical animal models, and more recently, assistance during oncologic surgery. However, conventional camera-based fluorescence imaging techniques are heavily surface-weighted such that surface reflection from skin or other nontumor tissue and nonspecific fluorescence signals dominate, obscuring true cancer-specific signals and blurring tumor boundaries. To address this challenge, we applied structured illumination fluorescence molecular imaging (SIFMI) in live animals for automated subtraction of nonspecific surface signals to better delineate accumulation of an NIR fluorescent probe targeting α4β1 integrin in mice bearing subcutaneous plasma cell xenografts. SIFMI demonstrated a fivefold improvement in tumor-to-background contrast when compared with other full-field fluorescence imaging methods and required significantly reduced scanning time compared with diffuse optical spectroscopy imaging. Furthermore, the spatial gradient mapping enhanced highlighting of tumor boundaries. Through the relatively simple hardware and software modifications described, SIFMI can be integrated with clinical fluorescence imaging systems, enhancing intraoperative tumor boundary delineation from the uninvolved tissue.

Polar Spacecraft Based Comparisons of Intense Electric Fields and Poynting Flux Near and Within the Plasma Sheet-Tail Lobe Boundary to UVI Images: An Energy Source for the Aurora

NASA Technical Reports Server (NTRS)

Wygant, J. R.; Keiling, A.; Cattell, C. A.; Johnson, M.; Lysak, R. L.; Temerin, M.; Mozer, F. S.; Kletzing, C. A.; Scudder, J. D.; Peterson, W.;

Polar spacecraft based comparisons of intense electric fields and Poynting flux near and within the plasma sheet-tail lobe boundary to UVI images: An energy source for the aurora

NASA Astrophysics Data System (ADS)

Wygant, J. R.; Keiling, A.; Cattell, C. A.; Johnson, M.; Lysak, R. L.; Temerin, M.; Mozer, F. S.; Kletzing, C. A.; Scudder, J. D.; Peterson, W.; Russell, C. T.; Parks, G.; Brittnacher, M.; Germany, G.; Spann, J.

2000-08-01

In this paper, we present measurements from two passes of the Polar spacecraft of intense electric and magnetic field structures associated with Alfven waves at and within the outer boundary of the plasma sheet at geocentric distances of 4-6 RE near local midnight. The electric field variations have maximum values exceeding 100 mV/m and are typically polarized approximately normal to the plasma sheet boundary. The electric field structures investigated vary over timescales (in the spacecraft frame) ranging from 1 to 30 s. They are associated with strong magnetic field fluctuations with amplitudes of 10-40 nT which lie predominantly in the plane of the plasma sheet and are perpendicular to the local magnetic field. The Poynting flux associated with the perturbation fields measured at these altitudes is about 1-2 ergs cm-2 s-1 and is directed along the average magnetic field direction toward the ionosphere. If the measured Poynting flux is mapped to ionospheric altitudes along converging magnetic field lines, the resulting energy flux ranges up to 100 ergs cm-2s-1. These strongly enhanced Poynting fluxes appear to occur in layers which are observed when the spacecraft is magnetically conjugate (to within a 1° mapping accuracy) to intense auroral structures as detected by the Polar UV Imager (UVI). The electron energy flux (averaged over a spatial resolution of 0.5° ) deposited in the ionosphere due to auroral electron beams as estimated from the intensity in the UVI Lyman-Birge-Hopfield-long filters is 15-30 ergs cm-2s-1. Thus there is evidence that these electric field structures provide sufficient Poynting flux to power the acceleration of auroral electrons (as well as the energization of upflowing ions and Joule heating of the ionosphere). During some events the phasing and ratio of the transverse electric and magnetic field variations are consistent with earthward propagation of Alfven surface waves with phase velocities of 4000-10000 km/s. During other events the phase shifts between electric and magnetic fields suggest interference between upward and downward propagating Alfven waves. The E/B ratios are about an order of magnitude larger than typical values of c/Σp, where Σp is the height integrated Pedersen conductivity. The contribution to the total energy flux at these altitudes from Poynting flux associated with Alfven waves is comparable to or larger than the contribution from the particle energy flux and 1-2 orders of magnitude larger than that estimated from the large-scale steady state convection electric field and field-aligned current system.

Imaging Magnetospheric Boundries at Ionospheric Heights

NASA Astrophysics Data System (ADS)

Baumgardner, J.; Nottingham, D.; Wroten, J.; Mendillo, M.

2001-12-01

Stable auroral red (SAR) arcs are excited by a downward heat flux within a narrow range of fluxtubes that define the plasmapause-ring current interaction region. Ambient F-region electrons near and above the peak height (300-500 km) are heated and collisionally excite atomic oxygen to the O(1D) state, thereby emitting 6300 A photons. At the same time, the diffuse aurora at 6300 A is excited by the precipitation of plasma sheet electrons into the lower thermosphere, exciting O(1D) to emit near 200 km. An all-sky imaging system operating at a sub-auroral site (e.g., at Millstone Hill) can readily record the SAR arc centroid location and the equatorial edge of the diffuse aurora in the same 6300 A image. We have analyzed 75 such cases showing where both stuctures occur in the ionosphere and then conducted field-line mapping to define the L-shell domains of origin in the equatorial plane of the inner magnetosphere (L ~ 2.5 - 4). To within the measurement and mapping accuracies, both boundaries coincide, i.e., the inner edge of the plasma sheet essentially falls along the plasmapause. Since the O(1D) 6300 A emission corresponds to ~2 ev of excitation by magnetospheric processes, this technique defines ELENA (Extremely Low Energetic Neutral Atom) imaging of magnetospheric structures.

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

Baker, D.; Van Driel-Gesztelyi, L.; Green, L. M.

Using spectra obtained by the EUV Imaging Spectrometer (EIS) instrument onboard Hinode, we present a detailed spatially resolved abundance map of an active region (AR)-coronal hole (CH) complex that covers an area of 359'' × 485''. The abundance map provides first ionization potential (FIP) bias levels in various coronal structures within the large EIS field of view. Overall, FIP bias in the small, relatively young AR is 2-3. This modest FIP bias is a consequence of the age of the AR, its weak heating, and its partial reconnection with the surrounding CH. Plasma with a coronal composition is concentrated atmore » AR loop footpoints, close to where fractionation is believed to take place in the chromosphere. In the AR, we found a moderate positive correlation of FIP bias with nonthermal velocity and magnetic flux density, both of which are also strongest at the AR loop footpoints. Pathways of slightly enhanced FIP bias are traced along some of the loops connecting opposite polarities within the AR. We interpret the traces of enhanced FIP bias along these loops to be the beginning of fractionated plasma mixing in the loops. Low FIP bias in a sigmoidal channel above the AR's main polarity inversion line, where ongoing flux cancellation is taking place, provides new evidence of a bald patch magnetic topology of a sigmoid/flux rope configuration.« less

Collocated ionosonde and dense GPS/GLONASS network measurements of midlatitude MSTIDs

NASA Astrophysics Data System (ADS)

Sherstyukov, R. O.; Akchurin, A. D.; Sherstyukov, O. N.

2018-04-01

To analyze midlatitude medium-scale travelling ionospheric disturbances (MSTIDs) over Kazan (55.5°N, 49°E), Russia, the sufficiently dense network of GNSS receivers (more than 150 ground-based stations) were used. For the first time, daytime MSTIDs in the form of their main signature (band structure) on high-resolution two-dimensional maps of the total electron content perturbation (TEC maps) are compared with ionosonde data with a high temporal resolution. For a pair of events, a relationship between southwestward TEC perturbations and evolution of F2 layer traces was established. So F2 peak frequency varied in antiphase to TEC perturbations. The ionograms show that during the movement of plasma depletion band (overhead ionosonde) the F2 peak frequency is the highest, and vice versa, for the plasma enhancement band, the F2 peak frequency is the lowest. One possible explanation may be a greater inclination of the radio beam from the vertical during the placement of a plasma enhancement band above the ionosonde, as evidenced by the absence of multiple reflections and the increased occurrence rate of additional cusp trace. Another possible explanation may be the redistribution of the electron content in the topside ionosphere with a small decrease in the F peak concentration of the layer with a small increase in TEC along the line-of-sight. Analysis of F2 peak frequency variation shows that observed peak-to-peak values of TEC perturbation equal to 0.4 and 1 TECU correspond to the values of ΔN/N equal to 13% and 28%. The need for further research is evident.

Tomographic reconstruction of tokamak plasma light emission using wavelet-vaguelette decomposition

NASA Astrophysics Data System (ADS)

Schneider, Kai; Nguyen van Yen, Romain; Fedorczak, Nicolas; Brochard, Frederic; Bonhomme, Gerard; Farge, Marie; Monier-Garbet, Pascale

2012-10-01

Images acquired by cameras installed in tokamaks are difficult to interpret because the three-dimensional structure of the plasma is flattened in a non-trivial way. Nevertheless, taking advantage of the slow variation of the fluctuations along magnetic field lines, the optical transformation may be approximated by a generalized Abel transform, for which we proposed in Nguyen van yen et al., Nucl. Fus., 52 (2012) 013005, an inversion technique based on the wavelet-vaguelette decomposition. After validation of the new method using an academic test case and numerical data obtained with the Tokam 2D code, we present an application to an experimental movie obtained in the tokamak Tore Supra. A comparison with a classical regularization technique for ill-posed inverse problems, the singular value decomposition, allows us to assess the efficiency. The superiority of the wavelet-vaguelette technique is reflected in preserving local features, such as blobs and fronts, in the denoised emissivity map.

Tomographic reconstruction of tokamak plasma light emission from single image using wavelet-vaguelette decomposition

NASA Astrophysics Data System (ADS)

Nguyen van yen, R.; Fedorczak, N.; Brochard, F.; Bonhomme, G.; Schneider, K.; Farge, M.; Monier-Garbet, P.

2012-01-01

Images acquired by cameras installed in tokamaks are difficult to interpret because the three-dimensional structure of the plasma is flattened in a non-trivial way. Nevertheless, taking advantage of the slow variation of the fluctuations along magnetic field lines, the optical transformation may be approximated by a generalized Abel transform, for which we propose an inversion technique based on the wavelet-vaguelette decomposition. After validation of the new method using an academic test case and numerical data obtained with the Tokam 2D code, we present an application to an experimental movie obtained in the tokamak Tore Supra. A comparison with a classical regularization technique for ill-posed inverse problems, the singular value decomposition, allows us to assess the efficiency. The superiority of the wavelet-vaguelette technique is reflected in preserving local features, such as blobs and fronts, in the denoised emissivity map.

The Heavy Ion Afternoon Bulge: Structure and Formation Mechanisms

NASA Astrophysics Data System (ADS)

Fernandes, P. A.; Larsen, B.; Skoug, R. M.; Reeves, G. D.; Denton, M.; Engel, M.; Ferradas, C.; Funsten, H. O.; Henderson, M. G.; Jahn, J. M.; Morley, S.; Thomsen, M. F.

2017-12-01

Recent observations of near-equatorial inner magnetosphere plasma composition indicate the presence of an "afternoon bulge" plasma population at low L-shell. A detailed statistical survey using HOPE data characterized this afternoon bulge as an enhancement in 10 keV O+ and He+ ions extending from 1100-2200 MLT and 2 ≤ L ≤ 4 during quiet/moderate geomagnetic activity (Kp < 5). This statistical HOPE study postulated that formation of the bulge is caused by variations in Kp: 10 keV particles have access to low L-shells during geomagnetically active times and become trapped during the transition to quiet times. In this study, we expand on previous observations of the afternoon bulge by examining individual transits of this feature by the Van Allen Probes. We analyze periods with optimal spacecraft transits of the afternoon bulge region, including: May - Oct. 2013, Feb. - June 2014, and Apr. - Aug. 2015. We determine the presence and duration of the bulge during case studies representing three categories of geomagnetic activity: 1) extended quiet geomagnetic conditions; 2) sharp transitions of Kp from active to quiet conditions; and 3) rises and falls in Kp on the time scales of spacecraft orbits to days. We thoroughly characterize the energy structure of the bulge as a function of Kp. We also analyze these transits of the bulge in the context of plasma access using both drift path modeling and UBK-derived energy access maps.

Enquiry into the Topology of Plasma Membrane-Localized PIN Auxin Transport Components.

PubMed

Nodzyński, Tomasz; Vanneste, Steffen; Zwiewka, Marta; Pernisová, Markéta; Hejátko, Jan; Friml, Jiří

2016-11-07

Auxin directs plant ontogenesis via differential accumulation within tissues depending largely on the activity of PIN proteins that mediate auxin efflux from cells and its directional cell-to-cell transport. Regardless of the developmental importance of PINs, the structure of these transporters is poorly characterized. Here, we present experimental data concerning protein topology of plasma membrane-localized PINs. Utilizing approaches based on pH-dependent quenching of fluorescent reporters combined with immunolocalization techniques, we mapped the membrane topology of PINs and further cross-validated our results using available topology modeling software. We delineated the topology of PIN1 with two transmembrane (TM) bundles of five α-helices linked by a large intracellular loop and a C-terminus positioned outside the cytoplasm. Using constraints derived from our experimental data, we also provide an updated position of helical regions generating a verisimilitude model of PIN1. Since the canonical long PINs show a high degree of conservation in TM domains and auxin transport capacity has been demonstrated for Arabidopsis representatives of this group, this empirically enhanced topological model of PIN1 will be an important starting point for further studies on PIN structure-function relationships. In addition, we have established protocols that can be used to probe the topology of other plasma membrane proteins in plants. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

Experimental Characterization of Magnetogasdynamic Phenomena in Ultra-High Velocity Pulsed Plasma Jets

NASA Astrophysics Data System (ADS)

Loebner, Keith; Wang, Benjamin; Cappelli, Mark

2014-10-01

The formation and propagation of high velocity plasma jets in a pulsed, coaxial, deflagration-type discharge is examined experimentally. A sensitive, miniaturized, immersed probe array is used to map out magnetic flux density and associated radial current density as a function of time and axial position. This array is also used to probe the magnetic field gradient across the exit of the accelerator and in the jet formation region. Sensitive interferometry via a continuous-wave helium-neon laser source is used to probe the structure of the plasma jet over multiple chords and axial locations. A two dimensional plasma density gradient profile at an instant in time during jet formation is compiled via Shack-Hartmann wavefront sensor analysis. The qualitative characteristics of rarefaction and/or shock wave formation as a function of chamber back-pressure is examined via fast-framing ICCD imaging. These measurements are compared to existing resistive MHD simulations of the coaxial deflagration accelerator and the ensuing rarefaction jet that is expelled from the electrode assembly. The physical mechanisms governing the behavior of the discharge and the formation of these high energy density plasma jets are proposed and validated against both theoretical models and numerically simulated behavior. This research was conducted with Government support under and awarded by DoD, Air Force Office of Scientific Research, National Defense Science and Engineering Graduate (NDSEG) Fellowship, 32 CFR 168a.

Mapping of lead, magnesium and copper accumulation in plant tissues by laser-induced breakdown spectroscopy and laser-ablation inductively coupled plasma mass spectrometry

NASA Astrophysics Data System (ADS)

Kaiser, J.; Galiová, M.; Novotný, K.; Červenka, R.; Reale, L.; Novotný, J.; Liška, M.; Samek, O.; Kanický, V.; Hrdlička, A.; Stejskal, K.; Adam, V.; Kizek, R.

2009-01-01

Laser-Induced Breakdown Spectroscopy (LIBS) and Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) were utilized for mapping the accumulation of Pb, Mg and Cu with a resolution up to 200 μm in a up to cm × cm area of sunflower ( Helianthus annuus L.) leaves. The results obtained by LIBS and LA-ICP-MS are compared with the outcomes from Atomic Absorption Spectrometry (AAS) and Thin-Layer Chromatography (TLC). It is shown that laser-ablation based analytical methods can substitute or supplement these techniques mainly in the cases when a fast multi-elemental mapping of a large sample area is needed.

Integral field spectroscopy of planetary nebulae: mapping the line diagnostics and hydrogen-poor zones with VLT FLAMES

NASA Astrophysics Data System (ADS)

Tsamis, Y. G.; Walsh, J. R.; Péquignot, D.; Barlow, M. J.; Danziger, I. J.; Liu, X.-W.

2008-05-01

Results from the first dedicated study of Galactic planetary nebulae (PNe) by means of optical integral field spectroscopy with the Very Large Telescope Fibre Large Array Multi Element Spectrograph Argus integral field unit are presented. Three typical Galactic disc PNe have been mapped with the 11.5 × 7.2-arcsec2 Argus array: 2D spectral maps of the main shell of NGC5882 and of large areas of NGC 6153 and NGC 7009 with 297 spatial pixels per target were obtained at subarcsec resolutions. A corresponding number of 297 spectra per target were obtained in the 396.4-507.8nm range. Spatially resolved maps of emission lines and of nebular physical properties such as electron temperatures, densities and ionic abundances were produced. The abundances of helium and of doubly ionized carbon and oxygen, relative to hydrogen, were derived from optical recombination lines (ORLs), while those of O2+ were also derived from the classic collisionally excited lines (CELs). The occurrence of the abundance discrepancy problem, pertaining to oxygen, was investigated by mapping the ratio of ORL/CEL abundances for O2+ [the abundance discrepancy factor (ADF)] across the face of the PNe. The ADF varies between targets and also with position within the targets, attaining values of ~40 in the case of NGC 6153 and ~30 in the case of NGC 7009. Correlations of the ADF with geometric distance from the central star and plasma surface brightness (for NGC 6153), as well as with [OIII] electron temperature, plasma ionization state and other physical properties of the targets are established. Very small values of the temperature fluctuation parameter in the plane of the sky, t2A(O2+), are found in all cases. It is argued that these results provide further evidence for the existence in run-of-the-mill PNe of a distinct nebular component consisting of hydrogen-deficient, super-metal-rich plasma. The zones containing this posited component appear as undulations in the CII and OII ORL abundance diagnostics of about 2 spatial pixels across, and so any associated structures should have physical sizes of less than ~1000 astronomical units. Regarding the origin of the inferred zones, we propose that circumstellar discs, Abell 30-type knots, or Helix-type cometary globules may be involved. Implications for emission-line studies of nebulae are discussed. Based on observations made with ESO telescopes at the Paranal Observatory under programme ID 075.D-0847(A). E-mail: ygt@star.ucl.ac.uk

Research of a possibility of receiving sorbents for a sewage disposal from a wastage of coal preparation factory

NASA Astrophysics Data System (ADS)

Buyantuev, S. L.; Kondratenko, A. S.; Shishulkin, S. Y.; Stebenkova, Y. Y.; Khmelev, A. B.

2017-05-01

The paper presents the results of the studies of the structure and porosity of the coal cake processed by electric arc plasma. The main limiting factor in processing of coal cakes sorbents is their high water content. As a result of coal washing, the main share of water introduced into the cake falls on hard-hydrate and colloidal components. This makes impossible application of traditional processes of manufacturing from a cake of coal sorbents. Using the electric arc intensifies the processes of thermal activation of coal cakes associated with thermal shock, destruction and vapor-gas reactions occurring at the surfaces of the particles at an exposure temperature of up to 3000 °C, which increases the title product outlet (sorbent) and thereby reduces manufacturing costs and improves environmental performance. The investigation of the thermal activation zone is carried out in the plasma reactor chamber by thermal imaging method followed by mapping-and 3D-modeling of temperature fields. the most important physical and chemical properties of the sorbents from coal cake activated by plasma was studied. The obtained results showed the possibility of coal cake thermal activation by electric arc plasma to change its material composition, the appearance of porosity and associated sorption capacity applied for wastewater treatment.

The plasma membrane recycling pathway and cell polarity in plants: studies on PIN proteins.

PubMed

Boutté, Yohann; Crosnier, Marie-Thérèse; Carraro, Nicola; Traas, Jan; Satiat-Jeunemaitre, Béatrice

2006-04-01

The PIN-FORMED (PIN) proteins are plasma-membrane-associated facilitators of auxin transport. They are often targeted to one side of the cell only through subcellular mechanisms that remain largely unknown. Here, we have studied the potential roles of the cytoskeleton and endomembrane system in the localisation of PIN proteins. Immunocytochemistry and image analysis on root cells from Arabidopsis thaliana and maize showed that 10-30% of the intracellular PIN proteins mapped to the Golgi network, but never to prevacuolar compartments. The remaining 70-90% were associated with yet to be identified structures. The maintenance of PIN proteins at the plasma membrane depends on a BFA-sensitive machinery, but not on microtubules and actin filaments. The polar localisation of PIN proteins at the plasmamembrane was not reflected by any asymmetric distribution of cytoplasmic organelles. In addition, PIN proteins were inserted in a symmetrical manner at both sides of the cell plate during cytokinesis. Together, the data indicate that the localisation of PIN proteins is a postmitotic event, which depends on local characteristics of the plasma membrane and its direct environment. In this context, we present evidence that microtubule arrays might define essential positional information for PIN localisation. This information seems to require the presence of an intact cell wall.

Fine-mapping, mutation analyses, and structural mapping of cerebrotendinous xanthomatosis in U.S. pedigrees.

PubMed

Lee, M H; Hazard, S; Carpten, J D; Yi, S; Cohen, J; Gerhardt, G T; Salen, G; Patel, S B

2001-02-01

Cerebrotendinous xanthomatosis (CTX) is a rare autosomal recessive disorder of bile acid biosynthesis. Clinically, CTX patients present with tendon xanthomas, juvenile cataracts, and progressive neurological dysfunction and can be diagnosed by the detection of elevated plasma cholestanol levels. CTX is caused by mutations affecting the sterol 27-hydroxylase gene (CYP27 ). CTX has been identified in a number of populations, but seems to have a higher prevalence in the Japanese, Sephardic Jewish, and Italian populations. We have assembled 12 previously unreported pedigrees from the United States. The CYP27 locus had been previously mapped to chromosome 2q33-qter. We performed linkage analyses and found no evidence of genetic heterogeneity. All CTX patients showed segregation with the CYP27 locus, and haplotype analysis and recombinant events allowed us to precisely map CYP27 to chromosome 2q35, between markers D2S1371 and D2S424. Twenty-three mutations were identified from 13 probands analyzed thus far; 11 were compound heterozygotes and 2 had homozygous mutations. Of these, five are novel mutations [Trp100Stop, Pro408Ser, Gln428Stop, a 10-base pair (bp) deletion in exon 1, and a 2-bp deletion in exon 6 of the CYP27 gene]. Three-dimensional structural modeling of sterol 27-hydroxylase showed that, while the majority of the missense mutations disrupt the heme-binding and adrenodoxin-binding domains critical for enzyme activity, two missense mutations (Arg94Trp/Gln and Lys226Arg) are clearly located outside these sites and may identify a potential substrate-binding or other protein contact site.

STUDY OF THE 3D GEOMETRIC STRUCTURE AND TEMPERATURE OF A CORONAL CAVITY USING THE LIMB SYNOPTIC MAP METHOD

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

Karna, N.; Pesnell, W. Dean; Webber, S. A. Hess

2015-09-10

We present the three-dimensional geometric structure and thermal properties of a coronal cavity deduced from limb synoptic maps. The observations are extreme ultraviolet images from the Atmospheric Imager Assembly (AIA) and magnetic images from the Helioseismic Magnetic Imager instruments on board the Solar Dynamics Observatory. We describe a limb synoptic-map method used to effectively identify and measure cavities from annuli of radiance above the solar limb. We find that cavities are best seen in the 211, 193, and 171 Å passbands. The prominence associated with each cavity is best seen in the 304 Å synoptic maps. We also estimate themore » thermal properties of the cavity and surrounding plasma by combining the AIA radiances with a differential emission measure analysis. This paper focuses on one long cavity from a catalog of coronal cavities that we are developing. Cavities in this catalog are designated by a coded name using the Carrington Rotation number and position. Cavity C211347177N was observed during Carrington Rotation 2113 at the northwestern limb of the solar disk with an average latitude of 47° N and a central longitude of 177°. We showed the following. (1) The cavity is a long tube with an elliptical cross-section with ratios of the length to width and the length to height of 11:1 and 7:1, respectively. (2) The cavity is about 1360 Mm long, or 170° in longitude. (3) It is tilted in latitude. (4) And it is slightly hotter than its surroundings.« less

IBEX-lo Sky Maps of Secondary Interstellar Neutrals Helium and Oxygen

NASA Astrophysics Data System (ADS)

Kucharek, H.; Isenberg, P. A.; Jeewoo, P.; Kubiak, M. A.; Bzowski, M.

2017-12-01

There are several populations of heliospheric energetic neutral atoms (ENAs) generated at the various heliospheric interfaces, the inner heliosheath, outer heliosheath (OHS), and the termination shock (TS). Depending on where and how these ENAs are generated, they belong to different energy regimes. While interstellar neutral (ISN) particles flow through the heliospheric boundary is mostly unimpeded, a substantial fraction of ISN H and O is filtered through charge exchange with ambient plasma ions before reaching the TS. Secondary ISN atoms are generated by the charge exchange reaction between primary ISN atoms and interstellar ions in the outer heliosheath, forming walls of H and O in front of the heliopause (HP). The flowing interstellar plasma encounters the heliopause as an obstacle, which deflects the flow. Thus, secondary neutrals measured at 1 AU carry information about the deflected interstellar plasma and the shape of the heliopause that causes the deflection. Due to very different magnitudes of charge exchange cross sections, the main source of the secondary He is charge exchange with the OHS He+, while that of the secondary O is the charge exchange between interstellar O+ and the OHS H. Therefore, the oxygen results are drastically different from those of helium. Interstellar O+ ions behave in principle like the He+ particles with an over-density due to the plasma deceleration. The high density decelerated oxygen ions just upwind of the heliopause encounter an over-density in neutral hydrogen, the hydrogen wall, allowing frequent charge exchange that produce slow neutral oxygen atoms forming the oxygen wall. Thus, the distribution in the sky maps of secondary He and O carries information on the shape as well as the structures in front of it. To investigate the secondary component of the interstellar neutral in detail we have distinguish between the two secondary component's. We engaged theory and simulations for the primary and secondary components to determine differences of between measurements and model predicted data.

Imposed, ordered dust structures and other plasma features in a strongly magnetized plasma

NASA Astrophysics Data System (ADS)

Thomas, Edward; Leblanc, Spencer; Lynch, Brian; Konopka, Uwe; Merlino, Robert; Rosenberg, Marlene

2015-11-01

The Magnetized Dusty Plasma Experiment (MDPX) device has been in operation for just over one year. In that time, the MDPX device has been operating using a uniform magnetic field configuration up to 3.0 Tesla and has successfully produced plasmas and dusty plasmas at high magnetic fields. In these experimental studies, we have made observations of a new type of imposed, ordered structure in a dusty plasma at magnetic fields above 1 T. These dusty plasma structures are shown to scale inversely with neutral pressure and are shown to reflect the spatial structure of a wire mesh placed in the plasma. Additionally, recent measurements have been made that give insights into the effective potential that establishes the ordered structures in the plasma. In this presentation, we report on details of the imposed, ordered dusty plasma structure as well as filamentary features that also appear in the plasma and modify the confinement of the dusty plasma. This work is supported with funding from the NSF and Department of Energy.

The ameliorating effects of long-term electroacupuncture on cardiovascular remodeling in spontaneously hypertensive rats

PubMed Central

2014-01-01

Background The purpose of this study was to investigate the inhibitory effects of long-term electroacupuncture at BaiHui (DU20) and ZuSanLi (ST36) on cardiovascular remodeling in spontaneously hypertensive rats (SHR) and underlying mechanisms. Methods 6-weeks-old SHR or Wistar male rats were randomly, divided into 6 groups: the control group (SHR/Wistar), the non-acupoint electroacupuncture stimulation group (SHR-NAP/Wistar-NAP) and the electroacupuncture stimulation at DU20 and ST36 group (SHR-AP/Wistar-AP), 24 rats in each group. Rats were treated with or without electroacupuncture at DU20 and ST36, once every other day for a period of 8 weeks. The mean arterial pressure (MAP) was measured once every 2 weeks. By the end of the 8th week, the left ventricular structure and function were assessed by echocardiography. The content of angiotensin II (Ang II), endothelin-1 (ET-1) and nitric oxide (NO) in the plasma was determined using enzyme-linked immunosorbent assay. Histological studies on the heart and the ascending aorta were performed. The expression of angiotensin II type 1 receptor (AT1R), endothelin-1 type A receptor (ETAR), eNOS and iNOS in rat myocardium and ascending aorta was investigated by Western blotting. Results The MAP in SHR increased linearly over the observation period and significantly reduced following electroacupuncture as compared with sham control SHR rats, while no difference in MAP was observed in Wistar rats between electroacupuncture and sham control. The aortic wall thickness, cardiac hypertrophy and increased collagen level in SHR were attenuated by long term electroacupuncture. The content of Ang II, ET-1 in the plasma decreased, but the content of NO increased after electroacupuncture stimulation in SHR. Long term electroacupuncture significantly inhibited the expression of AT1R, ETAR and iNOS, whereas increased eNOS expression, in myocardium and ascending aorta of SHR. Conclusions The long term electroacupuncture stimulation at DU20 and ST36 relieves the increased MAP and cardiovascular abnormality in both structure and function in SHR, this beneficial action is most likely mediated via modulation of AT1R-AT1R-ET-1-ETAR and NOS/NO pathway. PMID:24685050

Preliminary Results on the Heat Deposition on Divertor Plate using Low MN Map

NASA Astrophysics Data System (ADS)

Ali, Halima; Punjabi, Alkesh; Boozer, Allen

2003-10-01

The study of magnetic field line behavior and the closely related plasma behavior are important not only for their tokamak application but also for their application to other Hamiltonian, or near-Hamiltonian, systems. The behavior of field lines near a tokamak separatrix has been studied extensively using various approaches. Our approach is called method of maps. In this paper, we introduce an area-preserving map called Low MN map. We first derive the map from the general theory of maps /1/, and then use it to calculate the effects of m = 1, n = 1 perturbations on the stochastic layer and magnetic footprint in single-null divertor tokamaks. We show that there are self-similarities, singularities, and topological equivalences in the pattern of physical parameters that characterize the stochastic layer and the magnetic footprint. Preliminary results in the investigation on the heat distribution on the divertor plate indicate multiple peaked in heat flux profile distributed radially across the divertor target when the amplitude is 10-3. This, and other features, are in good agreement with experimental observations. This work is done under the DOE grant number DE-FG02-01ER54624. 1. A. Punjabi et al, J. Plasma Phys. 52, 91 (1994).

SuperDARN convection and Sondrestrom plasma drift

NASA Astrophysics Data System (ADS)

Xu, L.; Koustov, A. V.; Thayer, J.; McCready, M. A.

2001-07-01

Plasma convection measurements by the Goose Bay and Stokkseyri SuperDARN radar pair and the Sondrestrom incoherent scatter radar are compared in three different ways, by looking at the line-of-sight (l-o-s) velocities, by comparing the SuperDARN vectors and corresponding Sondrestrom l-o-s velocities and by comparing the end products of the instruments, the convection maps. All three comparisons show overall reasonable agreement of the convection measurements though the data spread is significant and for some points a strong disagreement is obvious. The convection map comparison shows a tendency for the SuperDARN velocities to be often less than the Sondrestrom drifts for strong flows (velocities > 1000 m/s) and larger for weak flows (velocities < 500 m/s). On average, both effects do not exceed 35%. Data indicate that inconsistencies between the two data sets occur largely at times of fast temporal variations of the plasma drift and for strongly irregular flow ac-cording to the SuperDARN convection maps. These facts indicate that the observed discrepancies are in many cases a result of the different spatial and temporal resolutions of the instruments.

FLOWS AND WAVES IN BRAIDED SOLAR CORONAL MAGNETIC STRUCTURES

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

Pant, V.; Datta, A.; Banerjee, D., E-mail: vaibhav@iiap.res.in

We study the high frequency dynamics in the braided magnetic structure of an active region (AR 11520) moss as observed by the High-Resolution Coronal Imager (Hi-C). We detect quasi-periodic flows and waves in these structures. We search for high frequency dynamics while looking at power maps of the observed region. We find that shorter periodicities (30–60 s) are associated with small spatial scales which can be resolved by Hi-C only. We detect quasi-periodic flows with a wide range of velocities, from 13–185 km s{sup −1}, associated with braided regions. This can be interpreted as plasma outflows from reconnection sites. Wemore » also find short period and large amplitude transverse oscillations associated with the braided magnetic region. Such oscillations could be triggered by reconnection or such oscillations may trigger reconnection.« less

EIT: Solar corona synoptic observations from SOHO with an Extreme-ultraviolet Imaging Telescope

NASA Technical Reports Server (NTRS)

Delaboudiniere, J. P.; Gabriel, A. H.; Artzner, G. E.; Michels, D. J.; Dere, K. P.; Howard, R. A.; Catura, R.; Stern, R.; Lemen, J.; Neupert, W.

1988-01-01

The Extreme-ultraviolet Imaging Telescope (EIT) of SOHO (solar and heliospheric observatory) will provide full disk images in emission lines formed at temperatures that map solar structures ranging from the chromospheric network to the hot magnetically confined plasma in the corona. Images in four narrow bandpasses will be obtained using normal incidence multilayered optics deposited on quadrants of a Ritchey-Chretien telescope. The EIT is capable of providing a uniform one arc second resolution over its entire 50 by 50 arc min field of view. Data from the EIT will be extremely valuable for identifying and interpreting the spatial and temperature fine structures of the solar atmosphere. Temporal analysis will provide information on the stability of these structures and identify dynamical processes. EIT images, issued daily, will provide the global corona context for aid in unifying the investigations and in forming the observing plans for SOHO coronal instruments.

Observations of subauroral ionospheric dynamics during SED plume passage at Millstone Hill

NASA Astrophysics Data System (ADS)

Zhang, S.; Erickson, P. J.; Coster, A. J.

2017-12-01

Storm enhanced density (SED) is a characteristic ionospheric storm time structure, with a significant plasma density enhancement in a narrow zone. SED structures often (but not always) span the continental US with a base in the US northeast at the afternoon and dusk sector, extending westward or northwest into the high latitude dayside cusp region. It is a typical and repeatable space weather phenomenon occurring during the main phase of magnetic storms with intensity ranging from active to disturbed levels. Observations of stormtime ionospheric density enhancement at subauroral latitudes have a long history, and were termed the 'dusk effect' until relatively recently, when dense networks of GNSS receivers have allowed us to view this structure with much finer spatial and temporal resolution. The formation of a SED plume is a topic under intensive community investigation, but in general it is believed that stormtime ionospheric dynamics and processes within the coupling magnetosphere-ionosphere-thermosphere system are responsible. For instance, poleward and sunward plasma drifts at the edge of the expanded dusk sector high-latitude convection can be important. Subauroral polarization stream (SAPS) are often observed at the poleward edge of the SED plume where ionospheric conductivity is low. SAPS is a huge westward ion flow that can convect ionospheric plasma from the afternoon or evening sector where solar photoionization production is waning, creating low density or density troughs. Stormtime penetration electric fields also exist, creating enhanced low and mid latitude upward ion drifts that move ionospheric plasma upward from the low altitude region where they are produced. This provides another important ionization source to contribute to maintaining the SED plume. This paper will provide analysis of the relative strength of these factors by using joint datasets of current geospace storm events obtained with the Millstone Hill incoherent scatter radar, GNSS TEC maps, and DMSP in situ measurements.

Winds of Massive Magnetic Stars: Interacting Fields and Flow

NASA Astrophysics Data System (ADS)

Daley-Yates, S.; Stevens, I. R.

2018-01-01

We present results of 3D numerical simulations of magnetically confined, radiatively driven stellar winds of massive stars, conducted using the astrophysical MHD code Pluto, with a focus on understanding the rotational variability of radio and sub-mm emission. Radiative driving is implemented according to the Castor, Abbott and Klein theory of radiatively driven winds. Many magnetic massive stars posses a magnetic axis which is inclined with respect to the rotational axis. This misalignment leads to a complex wind structure as magnetic confinement, centrifugal acceleration and radiative driving act to channel the circumstellar plasma into a warped disk whose observable properties should be apparent in multiple wavelengths. This structure is analysed to calculate free-free thermal radio emission and determine the characteristic intensity maps and radio light curves.

Digital holographic interferometry employing Fresnel transform reconstruction for the study of flow shear stabilized Z-pinch plasmas.

PubMed

Ross, M P; Shumlak, U

2016-10-01

The ZaP-HD flow Z-pinch project provides a platform to explore how shear flow stabilized Z-pinches could scale to high-energy-density plasma (plasma with pressures exceeding 1 Mbar) and fusion reactor conditions. The Z-pinch is a linear plasma confinement geometry in which the plasma carries axial electric current and is confined by its self-induced magnetic field. ZaP-HD generates shear stabilized, axisymmetric Z-pinches with stable lifetimes approaching 60 μs. The goal of the project is to increase the plasma density and temperature compared to the previous ZaP project by compressing the plasma to smaller radii (≈1 mm). Radial and axial plasma electron density structure is measured using digital holographic interferometry (DHI), which provides the necessary fine spatial resolution. ZaP-HD's DHI system uses a 2 ns Nd:YAG laser pulse with a second harmonic generator (λ = 532 nm) to produce holograms recorded by a Nikon D3200 digital camera. The holograms are numerically reconstructed with the Fresnel transform reconstruction method to obtain the phase shift caused by the interaction of the laser beam with the plasma. This provides a two-dimensional map of line-integrated electron density, which can be Abel inverted to determine the local number density. The DHI resolves line-integrated densities down to 3 × 10 20 m -2 with spatial resolution near 10 μm. This paper presents the first application of Fresnel transform reconstruction as an analysis technique for a plasma diagnostic, and it analyzes the method's accuracy through study of synthetic data. It then presents an Abel inversion procedure that utilizes data on both sides of a Z-pinch local number density profile to maximize profile symmetry. Error estimation and Abel inversion are applied to the measured data.

Detection of an electron beam in a high density plasma via an electrostatic probe

NASA Astrophysics Data System (ADS)

Majeski, Stephen; Yoo, Jongsoo; Zweben, Stewart; Yamada, Masaaki

2018-07-01

An electron beam is detected by a 1D floating potential probe array in a relatively high density (1012–1013 cm‑3) and low temperature (∼5 eV) plasma of the Magnetic Reconnection Experiment. Clear perturbations in the floating potential profile by the electron beam are observed. Based on the floating potential profile and a current balance equation to the probe array tips, the effective width of the electron beam is determined, from which we determine the radial and toroidal beam current density profiles. After the profile of the electron beam is specified from the measured beam current, we demonstrate the consistency of the current balance equation and the location of the perturbation is also in agreement with field line mapping. No significant broadening of the electron beam is observed after the beam propagates for tens of centimeters through the high density plasma. These results prove that the field line mapping is, in principle, possible in high density plasmas.

Detection of an electron beam in a high density plasma via an electrostatic probe

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

Majeski, Stephen; Yoo, Jongsoo; Zweben, Stewart

Here, an electron beam is detected by a 1D floating potential probe array in a relatively high density (10 12–10 13 cm -3) and low temperature (~5 eV) plasma of the Magnetic Reconnection Experiment. Clear perturbations in the floating potential profile by the electron beam are observed. Based on the floating potential profile and a current balance equation to the probe array tips, the effective width of the electron beam is determined, from which we determine the radial and toroidal beam current density profiles. After the profile of the electron beam is specified from the measured beam current, we demonstratemore » the consistency of the current balance equation and the location of the perturbation is also in agreement with field line mapping. No significant broadening of the electron beam is observed after the beam propagates for tens of centimeters through the high density plasma. These results prove that the field line mapping is, in principle, possible in high density plasmas.« less

Detection of an electron beam in a high density plasma via an electrostatic probe

DOE PAGES

Majeski, Stephen; Yoo, Jongsoo; Zweben, Stewart; ...

2018-05-08

Here, an electron beam is detected by a 1D floating potential probe array in a relatively high density (10 12–10 13 cm -3) and low temperature (~5 eV) plasma of the Magnetic Reconnection Experiment. Clear perturbations in the floating potential profile by the electron beam are observed. Based on the floating potential profile and a current balance equation to the probe array tips, the effective width of the electron beam is determined, from which we determine the radial and toroidal beam current density profiles. After the profile of the electron beam is specified from the measured beam current, we demonstratemore » the consistency of the current balance equation and the location of the perturbation is also in agreement with field line mapping. No significant broadening of the electron beam is observed after the beam propagates for tens of centimeters through the high density plasma. These results prove that the field line mapping is, in principle, possible in high density plasmas.« less

Rotation number of integrable symplectic mappings of the plane

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

Zolkin, Timofey; Nagaitsev, Sergei; Danilov, Viatcheslav

2017-04-11

Symplectic mappings are discrete-time analogs of Hamiltonian systems. They appear in many areas of physics, including, for example, accelerators, plasma, and fluids. Integrable mappings, a subclass of symplectic mappings, are equivalent to a Twist map, with a rotation number, constant along the phase trajectory. In this letter, we propose a succinct expression to determine the rotation number and present two examples. Similar to the period of the bounded motion in Hamiltonian systems, the rotation number is the most fundamental property of integrable maps and it provides a way to analyze the phase-space dynamics.

Chaos in Magnetic Flux Ropes

NASA Astrophysics Data System (ADS)

Gekelman, W. N.; DeHaas, T.; Van Compernolle, B.

2013-12-01

Magnetic Flux Ropes Immersed in a uniform magnetoplasma are observed to twist about themselves, writhe about each other and rotate about a central axis. They are kink unstable and smash into one another as they move. Full three dimensional magnetic field and flows are measured at thousands of time steps. Each collision results in magnetic field line generation and the generation of a quasi-seperatrix layer and induced electric fields. Three dimensional magnetic field lines are computed by conditionally averaging the data using correlation techniques. The permutation entropy1 ,which is related to the Lyapunov exponent, can be calculated from the the time series of the magnetic field data (this is also done with flows) and used to calculate the positions of the data on a Jensen Shannon complexity map2. The location of data on this map indicates if the magnetic fields are stochastic, or fall into regions of minimal or maximal complexity. The complexity is a function of space and time. The complexity map, and analysis will be explained in the course of the talk. Other types of chaotic dynamical models such as the Lorentz, Gissinger and Henon process also fall on the map and can give a clue to the nature of the flux rope turbulence. The ropes fall in the region of the C-H plane where chaotic systems lie. The entropy and complexity change in space and time which reflects the change and possibly type of chaos associated with the ropes. The maps give insight as to the type of chaos (deterministic chaos, fractional diffusion , Levi flights..) and underlying dynamical process. The power spectra of much of the magnetic and flow data is exponential and Lorentzian structures in the time domain are embedded in them. Other quantities such as the Hurst exponent are evaluated for both magnetic fields and plasma flow. Work Supported by a UC-LANL Lab fund and the Basic Plasma Science Facility which is funded by DOE and NSF. 1) C. Bandt, B. Pompe, Phys. Rev. Lett., 88,174102 (2007) 2) O. Russo et al., Phys. Rev. Lett., 99, 154102 (2007), J. Maggs, G.Morales, 55, 085015 (2013)

The gaseous plasmonic response of a one-dimensional photonic crystal composed of striated plasma layers

NASA Astrophysics Data System (ADS)

Wang, B.; Righetti, F.; Cappelli, M. A.

2018-03-01

We present simulations of the response of a one-dimensional striated plasma slab to incident electromagnetic waves that span regions both above and below the plasma frequency, ωp. Photonic bandgap modes are present throughout these regions, and volume and surface plasmon modes facilitate the response below ωp, where the dielectric constant, ɛp < 0. In the vicinity of ωp, most apparently, when ωp is in proximity of the lattice frequency, there is a feature for transverse magnetic (TM) polarization that is associated with the emergence of new dispersion branches. Also for TM polarization, a very low frequency mode emerges outside of the light line. Both these features are plasmonic and are attributed to the excitation of symmetric and asymmetric surface plasmon polaritons (SPPs) at the plasma-dielectric interface of the multi-layer plasma slabs. The features seen in the bandgap maps near ωp reveal the possible presence of Fano resonances between the symmetric branch of the SPP and the Bragg resonance as a narrow stop band (anti-node) is superimposed on the otherwise broad transmission band seen for transverse-electric polarization. We provide renderings that allow the visualization of where the transmission bands are and compute the transmittance and reflectance to facilitate the design and interpretation of experiments. The transmission bands associated with photonic bandgap modes above the plasma frequency are rather broad. The plasmonic modes, i.e., those associated with ɛp ≤ 0, can be quite narrow and are tuned by varying the plasma density, affording an opportunity for the application of these structures as ultra-narrow tunable microwave transmission filters.

New SuperDARN Radar Capabilities for Observing Ionospheric Plasma Convection and ITM Coupling in the Mid-Latitude Ionosphere

NASA Astrophysics Data System (ADS)

Ruohoniemi, J. M.; Baker, J. B.; Greenwald, R. A.; Clausen, L. B.; Shepherd, S. G.; Bristow, W. A.; Talaat, E. R.; Barnes, R. J.

2010-12-01

Within the past year the first pair of SuperDARN radars funded under the NSF MSI program has become operational at a site near Hays, Kansas. The fields of view of the co-located radars are oriented to provide common-volume observations with two existing radars in Virginia (Wallops, Blackstone) and two MSI radars under construction in Oregon (Christmas Valley). The emerging mid-latitude radar chain will complement the existing SuperDARN coverage at polar cap and auroral latitudes within North America. The mid-latitude radars observe the expansion of auroral effects during disturbed periods, subauroral polarization streams, and small-scale ionospheric irregularities on the nightside that open a window on the plasma drifts and electric fields of the quiet-time subauroral ionosphere. They also measure neutral winds at mesospheric heights and the propagation of ionospheric disturbances due to the passage of atmospheric gravity waves. The new radar capabilities provide unprecedented views of ITM processes in the subauroral ionosphere with applications to studies of ionospheric electric fields, ion-neutral coupling, atmospheric tides and planetary waves, ionospheric plasma structuring and plasma instability. In this talk we describe the new capabilities and the potential for providing large-scale context for related ITM measurements over North America. We present the first high-resolution two-dimensional maps of ionospheric plasma convection at mid-latitudes as generated from common-volume observations with the Hays and Blackstone radars.

A hemispherical Langmuir probe array detector for angular resolved measurements on droplet-based laser-produced plasmas

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

Gambino, Nadia, E-mail: gambinon@ethz.ch; Brandstätter, Markus; Rollinger, Bob

2014-09-15

In this work, a new diagnostic tool for laser-produced plasmas (LPPs) is presented. The detector is based on a multiple array of six motorized Langmuir probes. It allows to measure the dynamics of a LPP in terms of charged particles detection with particular attention to droplet-based LPP sources for EUV lithography. The system design permits to temporally resolve the angular and radial plasma charge distribution and to obtain a hemispherical mapping of the ions and electrons around the droplet plasma. The understanding of these dynamics is fundamental to improve the debris mitigation techniques for droplet-based LPP sources. The device hasmore » been developed, built, and employed at the Laboratory for Energy Conversion, ETH Zürich. The experimental results have been obtained on the droplet-based LPP source ALPS II. For the first time, 2D mappings of the ion kinetic energy distribution around the droplet plasma have been obtained with an array of multiple Langmuir probes. These measurements show an anisotropic expansion of the ions in terms of kinetic energy and amount of ion charge around the droplet target. First estimations of the plasma density and electron temperature were also obtained from the analysis of the probe current signals.« less

Observing heliospheric neutral atoms at 1 AU

NASA Astrophysics Data System (ADS)

Heerikhuisen, Jacob; Pogorelov, Nikolai; Florinski, Vladimir; Zank, Gary

2006-09-01

Although in situ observations of distant heliospheric plasma by the Voyagers has proven to be extremely enlightening, such point observations need to be complemented with global measurements taken remotely to obtain a complete picture of the heliosphere and local interstellar environment. Neutral atoms, with their contempt for magnetic fields, provide useful probes of the plasma that generated them. However, there will be a number of ambiguities in neutral atom readings that require a deeper understanding of the plasma processes generating neutral atoms, as well as the loss mechanisms on their flight to the observation point. We introduce a procedure for generating all-sky maps of energetic H-atoms, calculated directly in our Monte-Carlo neutral atom code. Results obtained for a self-consistent axisymmetric MHD-Boltzmann calculation, as well as several non-selfconsistent 3D sky maps, will be presented.

The Interstellar Heliopause Probe: Heliospheric Boundary Explorer Mission to the Interstellar Medium

NASA Astrophysics Data System (ADS)

Wimmer-Schweingruber, Robert F.; McNutt, Ralph

2009-04-01

The Sun, driving a supersonic solar wind, cuts out of the local interstellar medium a giant plasma bubble, the heliosphere. ESA, jointly with NASA, has had an important role in the development of our current understanding of the Suns’ immediate neighborhood. Ulysses is the only spacecraft exploring the third, out-of-ecliptic dimension, while SOHO has allowed us to better understand the influence of the Sun and to image the glow of interstellar matter in the heliosphere. Voyager 1 has recently encountered the innermost boundary of this plasma bubble, the termination shock, and is returning exciting yet puzzling data of this remote region. The next logical step is to leave the heliosphere and to thereby map out in unprecedented detail the structure of the outer heliosphere and its boundaries, the termination shock, the heliosheath, the heliopause, and, after leaving the heliosphere, to discover the true nature of the hydrogen wall, the bow shock, and the local interstellar medium beyond. This will greatly advance our understanding of the heliosphere that is the best-known example for astrospheres as found around other stars. Thus, IHP/HEX will allow us to discover, explore, and understand fundamental astrophysical processes in the largest accessible plasma laboratory, the heliosphere.

The Interstellar Heliopause Probe/Heliospheric Explorer: IHP/HEX

NASA Astrophysics Data System (ADS)

Wimmer-Schweingruber, Robert F.; McNutt, Ralph L.

2010-03-01

The Sun, driving a supersonic solar wind, cuts out of the local interstellar medium a giant plasma bubble, the heliosphere. Dedicated deep-space missions have greatly enhanced our understanding of our immediate neighborhood. Ulysses is the only spacecraft exploring the third, out-of-ecliptic dimension, while SOHO has allowed us to better understand the influence of the Sun and to image the glow of interstellar matter in the heliosphere. Both Voyager spacecraft have recently encountered the innermost boundary of this plasma bubble, the termination shock, and are returning exciting yet puzzling data of this remote region. The next logical step is to leave the heliosphere and to thereby map out in unprecedented detail the structure of the outer heliosphere and its boundaries, the termination shock, the heliosheath, the heliopause, and, after leaving the heliosphere, to discover the true nature of the hydrogen wall, the bow shock, and the local interstellar medium beyond. This will greatly advance our understanding of the heliosphere that is the best-known example for astrospheres as found around other stars. Thus, IHP/HEX will allow us to discover, explore, and understand fundamental astrophysical processes in the largest accessible plasma laboratory, the heliosphere.

Brain Imaging and Blood Biomarker Abnormalities in Children With Autosomal Dominant Alzheimer Disease: A Cross-Sectional Study.

PubMed

Quiroz, Yakeel T; Schultz, Aaron P; Chen, Kewei; Protas, Hillary D; Brickhouse, Michael; Fleisher, Adam S; Langbaum, Jessica B; Thiyyagura, Pradeep; Fagan, Anne M; Shah, Aarti R; Muniz, Martha; Arboleda-Velasquez, Joseph F; Munoz, Claudia; Garcia, Gloria; Acosta-Baena, Natalia; Giraldo, Margarita; Tirado, Victoria; Ramírez, Dora L; Tariot, Pierre N; Dickerson, Bradford C; Sperling, Reisa A; Lopera, Francisco; Reiman, Eric M

2015-08-01

Brain imaging and fluid biomarkers are characterized in children at risk for autosomal dominant Alzheimer disease (ADAD). To characterize and compare structural magnetic resonance imaging (MRI), resting-state and task-dependent functional MRI, and plasma amyloid-β (Aβ) measurements in presenilin 1 (PSEN1) E280A mutation-carrying and noncarrying children with ADAD. Cross-sectional measures of structural and functional MRI and plasma Aβ assays were assessed in 18 PSEN1 E280A carriers and 19 noncarriers aged 9 to 17 years from a Colombian kindred with ADAD. Recruitment and data collection for this study were conducted at the University of Antioquia and the Hospital Pablo Tobon Uribe in Medellín, Colombia, between August 2011 and June 2012. All participants had blood sampling, structural MRI, and functional MRI during associative memory encoding and resting-state and cognitive assessments. Outcome measures included plasma Aβ1-42 concentrations and Aβ1-42:Aβ1-40 ratios, memory encoding-dependent activation changes, resting-state connectivity, and regional gray matter volumes. Structural and functional MRI data were compared using automated brain mapping algorithms and search regions related to AD. Similar to findings in adult mutation carriers, in the later preclinical and clinical stages of ADAD, mutation-carrying children were distinguished from control individuals by significantly higher plasma Aβ1-42 levels (mean [SD]: carriers, 18.8 [5.1] pg/mL and noncarriers, 13.1 [3.2] pg/mL; P < .001) and Aβ1-42:Aβ1-40 ratios (mean [SD]: carriers, 0.32 [0.06] and noncarriers, 0.21 [0.03]; P < .001), as well as less memory encoding task-related deactivation in parietal regions (eg, mean [SD] parameter estimates for the right precuneus were -0.590 [0.50] for noncarriers and -0.087 [0.38] for carriers; P < .005 uncorrected). Unlike carriers in the later stages, mutation-carrying children demonstrated increased functional connectivity of the posterior cingulate cortex with medial temporal lobe regions (mean [SD] parameter estimates were 0.038 [0.070] for noncarriers and 0.190 [0.057] for carriers), as well as greater gray matter volumes in temporal regions (eg, left parahippocampus; P < . 049, corrected for multiple comparisons). Children at genetic risk for ADAD have functional and structural brain changes and abnormal levels of plasma Aβ1-42. The extent to which the underlying brain changes are either neurodegenerative or developmental remains to be determined. This study provides additional information about the earliest known biomarker changes associated with ADAD.

The Adipophilin C Terminus Is a Self-folding Membrane-binding Domain That Is Important for Milk Lipid Secretion*

PubMed Central

Chong, Brandi M.; Russell, Tanya D.; Schaack, Jerome; Orlicky, David J.; Reigan, Philip; Ladinsky, Mark; McManaman, James L.

2011-01-01

Cytoplasmic lipid droplets (CLD) in mammary epithelial cells undergo secretion by a unique membrane envelopment process to produce milk lipids. Adipophilin (ADPH/Plin2), a member of the perilipin/PAT family of lipid droplet-associated proteins, is hypothesized to mediate CLD secretion through interactions with apical plasma membrane elements. We found that the secretion of CLD coated by truncated ADPH lacking the C-terminal region encoding a putative four-helix bundle structure was impaired relative to that of CLD coated by full-length ADPH. We used homology modeling and analyses of the solution and membrane binding properties of purified recombinant ADPH C terminus to understand how this region possibly mediates CLD secretion. Homology modeling supports the concept that the ADPH C terminus forms a four-helix bundle motif and suggests that this structure can form stable membrane bilayer interactions. Circular dichroism and protease mapping studies confirmed that the ADPH C terminus is an independently folding α-helical structure that is relatively resistant to urea denaturation. Liposome binding studies showed that the purified C terminus binds to phospholipid membranes through electrostatic dependent interactions, and cell culture studies documented that it localizes to the plasma membrane. Collectively, these data provide direct evidence that the ADPH C terminus forms a stable membrane binding helical structure that is important for CLD secretion. We speculate that interactions between the four-helix bundle of ADPH and membrane phospholipids may be an initial step in milk lipid secretion. PMID:21383012

Linear and nonlinear response of a rotating tokamak plasma to a resonant error-field

NASA Astrophysics Data System (ADS)

Fitzpatrick, Richard

2014-09-01

An in-depth investigation of the effect of a resonant error-field on a rotating, quasi-cylindrical, tokamak plasma is preformed within the context of constant-ψ, resistive-magnetohydrodynamical theory. General expressions for the response of the plasma at the rational surface to the error-field are derived in both the linear and nonlinear regimes, and the extents of these regimes mapped out in parameter space. Torque-balance equations are also obtained in both regimes. These equations are used to determine the steady-state plasma rotation at the rational surface in the presence of the error-field. It is found that, provided the intrinsic plasma rotation is sufficiently large, the torque-balance equations possess dynamically stable low-rotation and high-rotation solution branches, separated by a forbidden band of dynamically unstable solutions. Moreover, bifurcations between the two stable solution branches are triggered as the amplitude of the error-field is varied. A low- to high-rotation bifurcation is invariably associated with a significant reduction in the width of the magnetic island chain driven at the rational surface, and vice versa. General expressions for the bifurcation thresholds are derived and their domains of validity mapped out in parameter space.

Fine structure of striations observed in barium plasma injections in the magnetospheric cleft

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

Simons, D.J.; Eastman, T.E.; Pongratz, M.B.

1976-01-01

In January and November of 1975, the Los Alamos Scientific Laboratory sponsored four high altitude shaped charge barium plasma injections in the magnetospheric cleft region. These experiments were TORDO UNO (January 6), TORDO DOS (January 11), PERIQUITO UNO (November 25), and PERIQUITO DOS (November 28). All four injections took place near 500 km altitude, and optical data were taken from two aircraft and a ground station. The TORDO DOS and the PERIQUITO experiments showed rapid formation of striations (within one minute after injection), and fast horizontal spreading in contrast with TORDO UNO. In PERIQUITO DOS, the debris cloud spread magneticallymore » east-west with a small net northerly motion. TORDO UNO shows very rapid poleward motion, and the remaining two events resulted in magnetically east-west horizontal spreading, with no noticeable poleward motion. Striations observed in the PERIQUITO DOS experiment separate in opposite directions with relative velocities of up to 3 km/sec. These field-aligned structures appear to form in sheets of approximately constant magnetic latitude. Significant spatial variations occur on a scale of less than 200 meters. Spatial frequency power spectra across these striations have been determined at various times. Observations of the debris cloud and the fast barium streak show strong field-aligned coherency of striation fine structure, indicating a field line mapping of transverse electric fields and gradients.« less

3D Mapping of plasma effective areas via detection of cancer cell damage induced by atmospheric pressure plasma jets

NASA Astrophysics Data System (ADS)

Han, Xu; Liu, Yueing; Stack, M. Sharon; Ptasinska, Sylwia

2014-12-01

In the present study, a nitrogen atmospheric pressure plasma jet (APPJ) was used for irradiation of oral cancer cells. Since cancer cells are very susceptible to plasma treatment, they can be used as a tool for detection of APPJ-effective areas, which extended much further than the visible part of the APPJ. An immunofluorescence assay was used for DNA damage identification, visualization and quantification. Thus, the effective damage area and damage level were determined and plotted as 3D images.

Can Polar Fields Explain Missing Open Flux?

NASA Astrophysics Data System (ADS)

Linker, J.; Downs, C.; Caplan, R. M.; Riley, P.; Mikic, Z.; Lionello, R.

2017-12-01

The "open" magnetic field is the portion of the Sun's magnetic field that extends out into the heliosphere and becomes the interplanetary magnetic field (IMF). Both the IMF and the Sun's magnetic field in the photosphere have been measured for many years. In the standard paradigm of coronal structure, the open magnetic field originates primarily in coronal holes. The regions that are magnetically closed trap the coronal plasma and give rise to the streamer belt. This basic picture is qualitatively reproduced by models of coronal structure using photospheric magnetic fields as input. If this paradigm is correct, there are two primary observational constraints on the models: (1) The open field regions in the model should approximately correspond to coronal holes observed in emission, and (2) the magnitude of the open magnetic flux in the model should match that inferred from in situ spacecraft measurements. Linker et al. (2017, ApJ, submitted) investigated the July 2010 time period for a range of observatory maps and both PFSS and MHD models. We found that all of the model/map combinations underestimated the interplanetary magnetic flux, unless the modeled open field regions were larger than observed coronal holes. An estimate of the open magnetic flux made entirely from solar observations (combining detected coronal hole boundaries with observatory synoptic magnetic maps) also underestimated the interplanetary magnetic flux. The magnetic field near the Sun's poles is poorly observed and may not be well represented in observatory maps. In this paper, we explore whether an underestimate of the polar magnetic flux during this time period could account for the overall underestimate of open magnetic flux. Research supported by NASA, AFOSR, and NSF.

Controllable Surface Reorganization Engineering on Cobalt Phosphide Nanowire Arrays for Efficient Alkaline Hydrogen Evolution Reaction.

PubMed

Xu, Kun; Cheng, Han; Lv, Haifeng; Wang, Jingyu; Liu, Linqi; Liu, Si; Wu, Xiaojun; Chu, Wangsheng; Wu, Changzheng; Xie, Yi

2018-01-01

Developing highly efficient hydrogen evolution reaction (HER) catalysts in alkaline media is considered significant and valuable for water splitting. Herein, it is demonstrated that surface reorganization engineering by oxygen plasma engraving on electocatalysts successfully realizes a dramatically enhanced alkaline HER activity. Taking CoP nanowire arrays grown on carbon cloth (denoted as CoP NWs/CC) as an example, the oxygen plasma engraving can trigger moderate CoO x species formation on the surface of the CoP NWs/CC, which is visually verified by the X-ray absorption fine structure, high-resolution transmission electron microscopy, and energy-dispersive spectrometer (EDS) mapping. Benefiting from the moderate CoO x species formed on the surface, which can promote the water dissociation in alkaline HER, the surface reorganization of the CoP NWs/CC realizes almost fourfold enhanced alkaline HER activity and a 180 mV decreased overpotential at 100 mA cm -2 , compared with the pristine ones. More interestingly, this surface reorganization strategy by oxygen plasma engraving can also be effective to other electrocatalysts such as free-standing CoP, Co 4 N, O-CoSe 2 , and C-CoSe 2 nanowires, which verifies the universality of the strategy. This work thus opens up new avenues for designing alkaline HER electrocatalysts based on oxygen plasma engraving. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Electric Propulsion Test and Evaluation Methodologies for Plasma in the Environments of Space and Testing (EP TEMPEST)

DTIC Science & Technology

2016-04-14

Swanson AEDC Path 1: Magnetized electron transport impeded across magnetic field lines; transport via electron-particle collisions Path 2*: Electron...T&E (higher pressure, metallic walls) → Impacts stability, performance, plume properties, thruster lifetime Magnetic Field Lines Plasma Plume...Development of T&E Methodologies • Current-Voltage- Magnetic Field (I-V-B) Mapping • Facility Interaction Studies • Background Pressure • Plasma Wall

Source of the dayside cusp aurora.

PubMed

Mende, S B; Frey, H U; Angelopoulos, V

2016-08-01

Monochromatic all-sky imagers at South Pole and other Antarctic stations of the Automatic Geophysical Observatory chain recorded the aurora in the region where the Time History of Events and Macroscale Interactions during Substorms (THEMIS) satellites crossed the dayside magnetopause. In several cases the magnetic field lines threading the satellites when mapped to the atmosphere were inside the imagers' field of view. From the THEMIS magnetic field and the plasma density measurements, we were able to locate the position of the magnetopause crossings and map it to the ionosphere using the Tsyganenko-96 field model. Field line mapping is reasonably accurate on the dayside subsolar region where the field is strong, almost dipolar even though compressed. From these coordinated observations, we were able to prove that the dayside cusp aurora of high 630 nm brightness is on open field lines, and it is therefore direct precipitation from the magnetosheath. The cusp aurora contained significant highly structured N 2 + 427.8 nm emission. The THEMIS measurements of the magnetosheath particle energy and density taken just outside the magnetopause compared to the intensity of the structured N 2 + 427.8 nm emissions showed that the precipitating magnetosheath particles had to be accelerated. The most likely electron acceleration mechanism is by dispersive Alfvén waves propagating along the field line. Wave-accelerated suprathermal electrons were seen by FAST and DMSP. The 427.8 nm wavelength channel also shows the presence of a lower latitude hard-electron precipitation zone originating inside the magnetosphere.

Source of the dayside cusp aurora

PubMed Central

Frey, H. U.; Angelopoulos, V.

2016-01-01

Abstract Monochromatic all‐sky imagers at South Pole and other Antarctic stations of the Automatic Geophysical Observatory chain recorded the aurora in the region where the Time History of Events and Macroscale Interactions during Substorms (THEMIS) satellites crossed the dayside magnetopause. In several cases the magnetic field lines threading the satellites when mapped to the atmosphere were inside the imagers' field of view. From the THEMIS magnetic field and the plasma density measurements, we were able to locate the position of the magnetopause crossings and map it to the ionosphere using the Tsyganenko‐96 field model. Field line mapping is reasonably accurate on the dayside subsolar region where the field is strong, almost dipolar even though compressed. From these coordinated observations, we were able to prove that the dayside cusp aurora of high 630 nm brightness is on open field lines, and it is therefore direct precipitation from the magnetosheath. The cusp aurora contained significant highly structured N2 + 427.8 nm emission. The THEMIS measurements of the magnetosheath particle energy and density taken just outside the magnetopause compared to the intensity of the structured N2 + 427.8 nm emissions showed that the precipitating magnetosheath particles had to be accelerated. The most likely electron acceleration mechanism is by dispersive Alfvén waves propagating along the field line. Wave‐accelerated suprathermal electrons were seen by FAST and DMSP. The 427.8 nm wavelength channel also shows the presence of a lower latitude hard‐electron precipitation zone originating inside the magnetosphere. PMID:27867797

Oscillations and Waves in Radio Source of Drifting Pulsation Structures

NASA Astrophysics Data System (ADS)

Karlický, Marian; Rybák, Ján; Bárta, Miroslav

2018-04-01

Drifting pulsation structures (DPSs) are considered to be radio signatures of the plasmoids formed during magnetic reconnection in the impulsive phase of solar flares. In the present paper we analyze oscillations and waves in seven examples of drifting pulsation structures, observed by the 800 - 2000 MHz Ondřejov Radiospectrograph. For their analysis we use a new type of oscillation maps, which give us much more information as regards processes in DPSs than that in previous analyses. Based on these oscillation maps, made from radio spectra by the wavelet technique, we recognized quasi-periodic oscillations with periods ranging from about 1 to 108 s in all studied DPSs. This strongly supports the idea that DPSs are generated during a fragmented magnetic reconnection. Phases of most the oscillations in DPSs, especially for the period around 1 s, are synchronized ("infinite" frequency drift) in the whole frequency range of DPSs. For longer periods in some DPSs we found that the phases of the oscillations drift with the frequency drift in the interval from -17 to +287 MHz s^{-1}. We propose that these drifting phases can be caused (a) by the fast or slow magnetosonic waves generated during the magnetic reconnection and propagating through the plasmoid, (b) by a quasi-periodic structure in the plasma inflowing to the reconnection forming a plasmoid, and (c) by a quasi-periodically varying reconnection rate in the X-point of the reconnection close to the plasmoid.

Calculation of stochastic broadening due to noise and field errors in the simple map in action-angle coordinates

NASA Astrophysics Data System (ADS)

Hinton, Courtney; Punjabi, Alkesh; Ali, Halima

2008-11-01

The simple map is the simplest map that has topology of divertor tokamaks [1]. Recently, the action-angle coordinates for simple map are analytically calculated, and simple map is constructed in action-angle coordinates [2]. Action-angle coordinates for simple map can not be inverted to real space coordinates (R,Z). Because there is logarithmic singularity on the ideal separatrix, trajectories can not cross separatrix [2]. Simple map in action-angle coordinates is applied to calculate stochastic broadening due to magnetic noise and field errors. Mode numbers for noise + field errors from the DIII-D tokamak are used. Mode numbers are (m,n)=(3,1), (4,1), (6,2), (7,2), (8,2), (9,3), (10,3), (11,3), (12,3) [3]. The common amplitude δ is varied from 0.8X10-5 to 2.0X10-5. For this noise and field errors, the width of stochastic layer in simple map is calculated. This work is supported by US Department of Energy grants DE-FG02-07ER54937, DE-FG02-01ER54624 and DE-FG02-04ER54793 1. A. Punjabi, H. Ali, T. Evans, and A. Boozer, Phys. Let. A 364, 140--145 (2007). 2. O. Kerwin, A. Punjabi, and H. Ali, to appear in Physics of Plasmas. 3. A. Punjabi and H. Ali, P1.012, 35^th EPS Conference on Plasma Physics, June 9-13, 2008, Hersonissos, Crete, Greece.

Post-suspension hypotension is attenuated in Sprague-Dawley rats by prostacyclin synthase inhibition

NASA Technical Reports Server (NTRS)

Bayorh, M. A.; Eatman, D.; Walton, M.; Socci, R. R.; Emmett, N.

2002-01-01

Cardiovascular deconditioning, sometimes manifested in astronauts during standing postflight, may be related to the impairment of autonomic function and/or excessive production of endothelium-dependent relaxing factors. In the present study, we examined the cardiovascular responses to 7-day 30 degrees tail-suspension and a subsequent 6-h post-suspension period in conscious male Sprague-Dawley rats to determine the role of prostacyclin in the observed post-suspension reduction in mean arterial pressure (MAP). The specific prostacyclin synthase inhibitor U-51605 (0.3 mg/kg), or saline, was administered intravenously prior to release from suspension and at 2 and 4 h post-suspension. During 7 days of suspension, MAP did not change, however, there was a post-suspension reduction in MAP which was associated with significant increases in plasma prostacyclin and nitric oxide. U-51605 attenuated the observed post-suspension hypotension and reduced plasma prostacyclin levels, but not nitric oxide levels. The baroreflex sensitivity for heart rate was modified by U-51605: increased MAP threshold and effective MAP range. Thus, the post-suspension reduction in mean arterial pressure may be due to overproduction of prostacyclin and/or other endothelium-dependent relaxing factors and alteration in baroreflex activity.

Visualizing fossilization using laser ablation-inductively coupled plasma-mass spectrometry maps of trace elements in Late Cretaceous bones

USGS Publications Warehouse

Koenig, A.E.; Rogers, R.R.; Trueman, C.N.

2009-01-01

Elemental maps generated by laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) provide a previously unavailable high-resolution visualization of the complex physicochemical conditions operating within individual bones during the early stages of diagenesis and fossilization. A selection of LA-ICP-MS maps of bones collected from the Late Cretaceous of Montana (United States) and Madagascar graphically illustrate diverse paths to recrystallization, and reveal unique insights into geochemical aspects of taphonomic history. Some bones show distinct gradients in concentrations of rare earth elements and uranium, with highest concentrations at external bone margins. Others exhibit more intricate patterns of trace element uptake related to bone histology and its control on the flow paths of pore waters. Patterns of element uptake as revealed by LA-ICP-MS maps can be used to guide sampling strategies, and call into question previous studies that hinge upon localized bulk samples of fossilized bone tissue. LA-ICP-MS maps also allow for comparison of recrystallization rates among fossil bones, and afford a novel approach to identifying bones or regions of bones potentially suitable for extracting intact biogeochemical signals. ?? 2009 Geological Society of America.

A Mapping Model for Magnetic Fields with q-profile Variations Typical of Internal Transport Barrier Experiments

NASA Astrophysics Data System (ADS)

Rapoport, B. I.; Pavlenko, I.; Weyssow, B.; Carati, D.

2002-11-01

Recent studies of ion and electron transport indicate that the safety factor profile, q(r), affects internal transport barrier (ITB) formation in magnetic confinement devices [1, 2]. These studies are consistent with experimental observations that low shear suppresses magnetic island interaction and associated stochasticity when the ITB is formed [3]. In this sense the position and quality of the ITB depend on the stochasticity of the magnetic field, and can be controlled by q(r). This study explores effects of the q-profile on magnetic field stochasticity using two-dimensional mapping techniques. Q-profiles typical of ITB experiments are incorporated into Hamiltonian maps to investigate the relation between magnetic field stochasticity and ITB parameters predicted by other models. It is shown that the mapping technique generates results consistent with these predictions, and suggested that Hamiltonian mappings can be useful as simple and computationally inexpensive approximation methods for describing the magnetic field in ITB experiments. 1. I. Voitsekhovitch et al. 29th EPS Conference on Plasma Physics and Controlled Fusion (2002). O-4.04. 2. G.M.D. Hogeweij et al. Nucl. Fusion. 38 (1998): 1881. 3. K.A. Razumova et al. Plasma Phys. Contr. Fusion. 42 (2000): 973.

Self-Consistent Chaotic Transport in a High-Dimensional Mean-Field Hamiltonian Map Model

DOE PAGES

Martínez-del-Río, D.; del-Castillo-Negrete, D.; Olvera, A.; ...

2015-10-30

We studied the self-consistent chaotic transport in a Hamiltonian mean-field model. This model provides a simplified description of transport in marginally stable systems including vorticity mixing in strong shear flows and electron dynamics in plasmas. Self-consistency is incorporated through a mean-field that couples all the degrees-of-freedom. The model is formulated as a large set of N coupled standard-like area-preserving twist maps in which the amplitude and phase of the perturbation, rather than being constant like in the standard map, are dynamical variables. Of particular interest is the study of the impact of periodic orbits on the chaotic transport and coherentmore » structures. Furthermore, numerical simulations show that self-consistency leads to the formation of a coherent macro-particle trapped around the elliptic fixed point of the system that appears together with an asymptotic periodic behavior of the mean field. To model this asymptotic state, we introduced a non-autonomous map that allows a detailed study of the onset of global transport. A turnstile-type transport mechanism that allows transport across instantaneous KAM invariant circles in non-autonomous systems is discussed. As a first step to understand transport, we study a special type of orbits referred to as sequential periodic orbits. Using symmetry properties we show that, through replication, high-dimensional sequential periodic orbits can be generated starting from low-dimensional periodic orbits. We show that sequential periodic orbits in the self-consistent map can be continued from trivial (uncoupled) periodic orbits of standard-like maps using numerical and asymptotic methods. Normal forms are used to describe these orbits and to find the values of the map parameters that guarantee their existence. Numerical simulations are used to verify the prediction from the asymptotic methods.« less

Self-Consistent Chaotic Transport in a High-Dimensional Mean-Field Hamiltonian Map Model

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

Martínez-del-Río, D.; del-Castillo-Negrete, D.; Olvera, A.

We studied the self-consistent chaotic transport in a Hamiltonian mean-field model. This model provides a simplified description of transport in marginally stable systems including vorticity mixing in strong shear flows and electron dynamics in plasmas. Self-consistency is incorporated through a mean-field that couples all the degrees-of-freedom. The model is formulated as a large set of N coupled standard-like area-preserving twist maps in which the amplitude and phase of the perturbation, rather than being constant like in the standard map, are dynamical variables. Of particular interest is the study of the impact of periodic orbits on the chaotic transport and coherentmore » structures. Furthermore, numerical simulations show that self-consistency leads to the formation of a coherent macro-particle trapped around the elliptic fixed point of the system that appears together with an asymptotic periodic behavior of the mean field. To model this asymptotic state, we introduced a non-autonomous map that allows a detailed study of the onset of global transport. A turnstile-type transport mechanism that allows transport across instantaneous KAM invariant circles in non-autonomous systems is discussed. As a first step to understand transport, we study a special type of orbits referred to as sequential periodic orbits. Using symmetry properties we show that, through replication, high-dimensional sequential periodic orbits can be generated starting from low-dimensional periodic orbits. We show that sequential periodic orbits in the self-consistent map can be continued from trivial (uncoupled) periodic orbits of standard-like maps using numerical and asymptotic methods. Normal forms are used to describe these orbits and to find the values of the map parameters that guarantee their existence. Numerical simulations are used to verify the prediction from the asymptotic methods.« less

Microstructure of In x Ga1-x N nanorods grown by molecular beam epitaxy

NASA Astrophysics Data System (ADS)

Webster, R. F.; Soundararajah, Q. Y.; Griffiths, I. J.; Cherns, D.; Novikov, S. V.; Foxon, C. T.

2015-11-01

Transmission electron microscopy is used to examine the structure and composition of In x Ga1-x N nanorods grown by plasma-assisted molecular beam epitaxy. The results confirm a core-shell structure with an In-rich core and In-poor shell resulting from axial and lateral growth sectors respectively. Atomic resolution mapping by energy-dispersive x-ray microanalysis and high angle annular dark field imaging show that both the core and the shell are decomposed into Ga-rich and In-rich platelets parallel to their respective growth surfaces. It is argued that platelet formation occurs at the surfaces, through the lateral expansion of surface steps. Studies of nanorods with graded composition show that decomposition ceases for x ≥ 0.8 and the ratio of growth rates, shell:core, decreases with increasing In concentration.

Scaling of Turbulence and Transport with ρ* in LAPD

NASA Astrophysics Data System (ADS)

Guice, Daniel; Carter, Troy; Rossi, Giovanni

2014-10-01

The plasma column size of the Large Plasma Device (LAPD) is varied in order to investigate the variation of turbulence and transport with ρ* =ρs / a . The data set includes plasmas produced by the standard BaO plasma source (straight field plasma radius a 30 cm) as well as the new higher density, higher temperature LaB6 plasma source (straight field plasma radius a 10 cm). The size of the plasma column is scaled in order to observe a Bohm to Gyro-Bohm diffusion transition. The main plasma column magnetic field is held fixed while the field in the cathode region is changed in order to map the cathode to different plasma column scales in the main chamber. Past experiments in the LAPD have shown a change in the observed diffusion but no transition to Gyro-Bohm diffusion. Results will be presented from an ongoing campaign to push the LAPD into the Gyro-Bohm diffusion regime.

System to continuously produce carbon fiber via microwave assisted plasma processing

DOEpatents

White, Terry L [Knoxville, TN; Paulauskas, Felix L [Knoxville, TN; Bigelow, Timothy S [Knoxville, TN

2010-11-02

A system to continuously produce fully carbonized or graphitized carbon fibers using microwave-assisted plasma (MAP) processing comprises an elongated chamber in which a microwave plasma is excited in a selected gas atmosphere. Fiber is drawn continuously through the chamber, entering and exiting through openings designed to minimize in-leakage of air. There is a gradient of microwave power within the chamber with generally higher power near where the fiber exits and lower power near where the fiber enters. Polyacrylonitrile (PAN), pitch, or any other suitable organic/polymeric precursor fibers can be used as a feedstock for the inventive system. Oxidized or partially oxidized PAN or pitch or other polymeric fiber precursors are run continuously through a MAP reactor in an inert, non-oxidizing atmosphere to heat the fibers, drive off the unwanted elements such as oxygen, nitrogen, and hydrogen, and produce carbon or graphite fibers faster than conventionally produced carbon fibers.

Transfer Orbit Plasma Interaction Experiment (TROPIX)

NASA Astrophysics Data System (ADS)

Hickman, Mark

Viewgraphs on the Transfer Orbit Plasma Interaction Experiment (TROPIX) are presented. Objectives of this research are (1) to map the charged particles in Earth's magnetosphere from LEO to GEO at high inclinations; (2) to measure plasma current collection and resulting shifts in vehicle electrical potential from LEO to GEO across range of orbital inclinations; (3) to study spacecraft interaction with plasma environment using solar electric propulsion (SEP) thrusters as plasma contactors; (4) to measure array degradation over mission duration; (5) to evaluate the potential of various microelectronics, spacecraft components, and instruments for future space missions; and (6) to demonstrate SEP technology applied to a flight vehicle. An overview of TROPIX is presented.

Mapping Nanoscale Absorption of Femtosecond Laser Pulses Using Plasma Explosion Imaging

DTIC Science & Technology

2014-08-06

Libby, S. B.; et al. Observation and Control of Shock Waves in Indivi- dual Nanoplasmas . Phys. Rev. Lett. 2014, 112, 115004. 17. Zhang, X.; Smith, K. a...Laser Light. Phys. Plasmas 2005, 12, 056703. 24. Lezius, M.; Dobosz, S. Hot Nanoplasmas from Intense Laser Irradiation of Argon Clusters. J. Phys. B

3D numerical simulations of negative hydrogen ion extraction using realistic plasma parameters, geometry of the extraction aperture and full 3D magnetic field map

NASA Astrophysics Data System (ADS)

Mochalskyy, S.; Wünderlich, D.; Ruf, B.; Franzen, P.; Fantz, U.; Minea, T.

2014-02-01

Decreasing the co-extracted electron current while simultaneously keeping negative ion (NI) current sufficiently high is a crucial issue on the development plasma source system for ITER Neutral Beam Injector. To support finding the best extraction conditions the 3D Particle-in-Cell Monte Carlo Collision electrostatic code ONIX (Orsay Negative Ion eXtraction) has been developed. Close collaboration with experiments and other numerical models allows performing realistic simulations with relevant input parameters: plasma properties, geometry of the extraction aperture, full 3D magnetic field map, etc. For the first time ONIX has been benchmarked with commercial positive ions tracing code KOBRA3D. A very good agreement in terms of the meniscus position and depth has been found. Simulation of NI extraction with different e/NI ratio in bulk plasma shows high relevance of the direct negative ion extraction from the surface produced NI in order to obtain extracted NI current as in the experimental results from BATMAN testbed.

Quantitative trait loci mapping of the mouse plasma proteome (pQTL).

PubMed

Holdt, Lesca M; von Delft, Annette; Nicolaou, Alexandros; Baumann, Sven; Kostrzewa, Markus; Thiery, Joachim; Teupser, Daniel

2013-02-01

A current challenge in the era of genome-wide studies is to determine the responsible genes and mechanisms underlying newly identified loci. Screening of the plasma proteome by high-throughput mass spectrometry (MALDI-TOF MS) is considered a promising approach for identification of metabolic and disease processes. Therefore, plasma proteome screening might be particularly useful for identifying responsible genes when combined with analysis of variation in the genome. Here, we describe a proteomic quantitative trait locus (pQTL) study of plasma proteome screens in an F(2) intercross of 455 mice mapped with 177 genetic markers across the genome. A total of 69 of 176 peptides revealed significant LOD scores (≥5.35) demonstrating strong genetic regulation of distinct components of the plasma proteome. Analyses were confirmed by mechanistic studies and MALDI-TOF/TOF, liquid chromatography-tandem mass spectrometry (LC-MS/MS) analyses of the two strongest pQTLs: A pQTL for mass-to-charge ratio (m/z) 3494 (LOD 24.9, D11Mit151) was identified as the N-terminal 35 amino acids of hemoglobin subunit A (Hba) and caused by genetic variation in Hba. Another pQTL for m/z 8713 (LOD 36.4; D1Mit111) was caused by variation in apolipoprotein A2 (Apoa2) and cosegregated with HDL cholesterol. Taken together, we show that genome-wide plasma proteome profiling in combination with genome-wide genetic screening aids in the identification of causal genetic variants affecting abundance of plasma proteins.

Quantitative Trait Loci Mapping of the Mouse Plasma Proteome (pQTL)

PubMed Central

Holdt, Lesca M.; von Delft, Annette; Nicolaou, Alexandros; Baumann, Sven; Kostrzewa, Markus; Thiery, Joachim; Teupser, Daniel

2013-01-01

A current challenge in the era of genome-wide studies is to determine the responsible genes and mechanisms underlying newly identified loci. Screening of the plasma proteome by high-throughput mass spectrometry (MALDI-TOF MS) is considered a promising approach for identification of metabolic and disease processes. Therefore, plasma proteome screening might be particularly useful for identifying responsible genes when combined with analysis of variation in the genome. Here, we describe a proteomic quantitative trait locus (pQTL) study of plasma proteome screens in an F2 intercross of 455 mice mapped with 177 genetic markers across the genome. A total of 69 of 176 peptides revealed significant LOD scores (≥5.35) demonstrating strong genetic regulation of distinct components of the plasma proteome. Analyses were confirmed by mechanistic studies and MALDI-TOF/TOF, liquid chromatography-tandem mass spectrometry (LC-MS/MS) analyses of the two strongest pQTLs: A pQTL for mass-to-charge ratio (m/z) 3494 (LOD 24.9, D11Mit151) was identified as the N-terminal 35 amino acids of hemoglobin subunit A (Hba) and caused by genetic variation in Hba. Another pQTL for m/z 8713 (LOD 36.4; D1Mit111) was caused by variation in apolipoprotein A2 (Apoa2) and cosegregated with HDL cholesterol. Taken together, we show that genome-wide plasma proteome profiling in combination with genome-wide genetic screening aids in the identification of causal genetic variants affecting abundance of plasma proteins. PMID:23172855

Repeated Administration of a Mutant Cocaine Esterase: Effects on Plasma Cocaine Levels, Cocaine-Induced Cardiovascular Activity, and Immune Responses in Rhesus Monkeys

PubMed Central

Collins, Gregory T.; Brim, Remy L.; Noon, Kathleen R.; Narasimhan, Diwahar; Lukacs, Nicholas W.; Sunahara, Roger K.; Woods, James H.

2012-01-01

Previous studies have demonstrated the capacity of a long-acting mutant form of a naturally occurring bacterial double mutant cocaine esterase (DM CocE) to antagonize the reinforcing, discriminative, convulsant, and lethal effects of cocaine in rodents and reverse the increases in mean arterial pressure (MAP) and heart rate (HR) produced by cocaine in rhesus monkeys. This study was aimed at characterizing the immunologic responses to repeated dosing with DM CocE and determining whether the development of anti-CocE antibodies altered the capacity of DM CocE to reduce plasma cocaine levels and ameliorate the cardiovascular effects of cocaine in rhesus monkeys. Under control conditions, intravenous administration of cocaine (3 mg/kg) resulted in a rapid increase in the plasma concentration of cocaine (n = 2) and long-lasting increases in MAP and HR (n = 3). Administration of DM CocE (0.32 mg/kg i.v.) 10 min after cocaine resulted in a rapid hydrolysis of cocaine with plasma levels below detection limits within 5 to 8 min. Elevations in MAP and HR were significantly reduced within 25 and 50 min of DM CocE administration, respectively. Although slight (10-fold) increases in anti-CocE antibodies were observed after the fourth administration of DM CocE, these antibodies did not alter the capacity of DM CocE to reduce plasma cocaine levels or ameliorate cocaine's cardiovascular effects. Anti-CocE titers were transient and generally dissipated within 8 weeks. Together, these results suggest that highly efficient cocaine esterases, such as DM CocE, may provide a novel and effective therapeutic for the treatment of acute cocaine intoxication in humans. PMID:22518021

Numerical band structure calculations of plasma metamaterials

NASA Astrophysics Data System (ADS)

Pederson, Dylan; Kourtzanidis, Konstantinos; Raja, Laxminarayan

2015-09-01

Metamaterials (MM) are materials engineered to display negative macroscopic permittivity and permeability. These materials allow for designed control over electromagnetic energy flow, especially at frequencies where natural materials do not interact. Plasmas have recently found application in MM as a negative permittivity component. The permittivity of a plasma depends on its electron density, which can be controlled by an applied field. This means that plasmas can be used in MM to actively control the transmission or reflection of incident waves. This work focuses on a plasma MM geometry in which microplasmas are generated in perforations in a metal plate. We characterizethis material by its band structure, which describes its interaction with incident waves. The plasma-EM interactions are obtained by coupling Maxwell's equations to a simplified plasma momentum equation. A plasma density profile is prescribed, and its effect on the band structure is investigated. The band structure calculations are typically done for static structures, whereas our current density responds to the incident waves. The resulting band structures are compared with experimental results.

Effects of acute and subchronic AT1 receptor blockade on cardiovascular, hydromineral and neuroendocrine responses in female rats.

PubMed

Araujo, Iracema Gomes; Elias, Lucila Leico Kagohara; Antunes-Rodrigues, José; Reis, Luís Carlos; Mecawi, Andre Souza

2013-10-02

Female Wistar rats were ovariectomized (OVX) and separated into two groups that received either estradiol cypionate (EC, 40 μg/kg, sc; OVX-EC) or vehicle (corn oil, sc; OVX-oil) for 14 consecutive days. On the 7th day of treatment, a subset of animals from both the OVX-oil and OVX-EC groups was subjected to subchronic losartan (AT1 receptor antagonist) treatment (0.1g/L in drinking water; ~15 mg/kg/day) for 7 days. Other group of OVX-oil and OVX-EC rats was submitted to an acute losartan injection (100mg/kg, ip) on the 14th day of hormone replacement. In both protocols, the following parameters were measured: I) mean arterial pressure (MAP) and heart rate (HR); II) water and 0.3M saline intake; III) angiotensin II (ANG II), atrial natriuretic peptide (ANP), vasopressin (AVP) and oxytocin (OT) plasma concentrations; and IV) urinary and plasma sodium concentrations. Acute AT1 blockade induced a significant reduction in the MAP in the OVX rats, resulting in increased HR and water intake, which were attenuated by estradiol therapy. Acute AT1 blockade also increased ANG II and OT and reduced ANP plasma concentrations, with no changes in AVP secretion. In addition, acute hypotension was accompanied by a decrease in natriuresis, which was unaltered by estradiol. Subchronic AT1 blockade induced a significant decrease in MAP without changing HR in both groups. Additionally, subchronic losartan treatment induced sodium appetite in OVX rats. Prolonged AT1 blockade increased ANG II and AVP and reduced ANP plasma concentrations. Moreover, it increased natriuresis but did not alter plasma OT concentrations. Finally, estradiol treatment attenuated the increase in salt intake and plasma ANG II concentrations induced by subchronic AT1 blockade. In conclusion, our results suggest differential adaptive responses to the acute or subchronic losartan treatment in OVX and OVX-EC rats. © 2013.

Studies of Nonlinear Phenomena in Plasmas.

DTIC Science & Technology

1980-03-01

Nonperiodic Oscillations of Langmuir Waves, UCLA Engr. Rpt. No. ENG- 7879 , Nov. 1978. .--- j, - :- -- ... . ___________ - - 8 V. PUBLICATIONS, REPORTS AND...OF CHAOTIC OSCILLATIONS ...... ............ 9 V. POINCARE MAPS ......... ...................... . 13 VI . CONCLUDING REMARKS...But the graphs of the Poincare maps in terms of some curve parameter are not readily obtainable. VI . CONCLUDING REMARKS The results of this study

Study of the internal structure, instabilities, and magnetic fields in the dense Z-pinch

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

Ivanov, Vladimir V.

Z-pinches are sources of hot dense plasma which generates powerful x-ray bursts and can been applied to various areas of high-energy-density physics (HEDP). The 26-MA Z machine is at the forefront of many of these applications, but important aspects of HEDP have been studied on generators at the 1 MA current level. Recent development of laser diagnostics and upgrade of the Leopard laser at Nevada Terawatt Facility (NTF) give new opportunities for the dense Z-pinch study. The goal of this project is the investigation of the internal structure of the stagnated Z pinch including sub-mm and micron-scale instabilities, plasma dynamics,more » magnetic fields, and hot spots formation and initiation. New plasma diagnostics will be developed for this project. A 3D structure and instabilities of the pinch will be compared with 3D MHD and spectroscopic modeling and theoretical analysis. The structure and dynamics of stagnated Z pinches has been studied with x-ray self-radiation diagnostics which derive a temperature map of the pinch with a spatial resolution of 70-150 µm. The regular laser diagnostics at 532 nm does not penetrate in the dense pinch due to strong absorption and refraction in trailing plasma. Recent experiments at NTF showed that shadowgraphy at the UV wavelength of 266 nm unfolds a fine structure of the stagnated Z-pinch with unprecedented detail. We propose to develop laser UV diagnostics for Z pinches with a spatial resolution <5 μm to study the small-scale plasma structures, implement two-frame shadowgraphy/interferometry, and develop methods for investigation of strong magnetic fields. New diagnostics will help to understand better basic physical processes in Z pinches. A 3D internal structure of the pinch and characteristic instabilities will be studied in wire arrays with different configurations and compared with 3D MHD simulations and analytical models. Mechanisms of “enhanced heating” of Z-pinch plasma will be studied. Fast dynamics of stagnated plasma will be studied to estimate its contribution to the Doppler broadening of x-ray lines. Development of “necks” and “hot spots” will be studied with high-resolution UV diagnostics, an x-ray streak camera, and x-ray spectroscopy. Laser initiation of hot spots in Z pinches will be tested. A Faraday rotation diagnostic at 266 nm will be applied to 1-10 MG magnetic fields. For magnetic fields B>20 MG, suggested in micropinches, Cotton-Mouton and cutoff diagnostics will be applied. A picosecond optical Kerr shutter will be tested to increase a sensitivity of UV methods for application at multi-MA Z pinches. The proposal is based on the experimental capability of NTF. The Zebra generator produces 1-1.7 MA Z-pinches with electron plasma density of 10 20-10 21cm -3, electron temperature of 0.5-1 keV, and magnetic fields >10 MG. The Leopard laser was upgraded to energy of 90-J at 0.8 ns. This regime will be used for laser initiation of hot spots. A further upgrade to energy of 250-J is suggested for laser-Z-pinch interaction. A picosecond regime will be used for optical gating. A 10-TW Tomcat laser at NTF is available for the high energy UV laser probing of the Z-pinch. Two graduate students will develop new optical and x-ray diagnostics, carry out experiments, and process experimental data. Other students will be involved in the design and fabrication of loads, supporting regular optical and x-ray diagnostics, and data processing. The new plasma diagnostics may be applied to HEDP experiments at NTF and other multi-MA generators. The feasibility of the research plan is based on the experience of the scientific team in Z-pinch plasma physics, laser physics, development of new plasma diagnostics, and the experimental capability of NTF. The experimental group of Dr. V. V. Ivanov (UNR) collaborates with a group for Z pinch MHD modeling of Dr. J. P. Chittenden (Imperial College, London), and theoretical group of Dr. D. D. Ryutov (LLNL). The suggested research ideas are supported by preliminary experiments.« less

Process for forming exoergic structures with the use of a plasma

DOEpatents

Kelly, M.D.

1987-05-29

A method of forming exoergic structures, as well as exoergic structures produced by the method, is provided. The method comprises the steps of passing a plasma-forming gas through a plasma spray gun, forming a plasma spray, introducing exoergic material into the plasma spray and directing the plasma spray toward a substrate, and allowing the exoergic material to become molten in the plasma spray and to thereafter impinge on the substrate to form a solid mass of exoergic material, the shape of which corresponds to the shape of the substrate.

Emergence of kinetic behavior in streaming ultracold neutral plasmas

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

McQuillen, P.; Castro, J.; Bradshaw, S. J.

2015-04-15

We create streaming ultracold neutral plasmas by tailoring the photoionizing laser beam that creates the plasma. By varying the electron temperature, we control the relative velocity of the streaming populations, and, in conjunction with variation of the plasma density, this controls the ion collisionality of the colliding streams. Laser-induced fluorescence is used to map the spatially resolved density and velocity distribution function for the ions. We identify the lack of local thermal equilibrium and distinct populations of interpenetrating, counter-streaming ions as signatures of kinetic behavior. Experimental data are compared with results from a one-dimensional, two-fluid numerical simulation.

Waves generated in the plasma plume of helicon magnetic nozzle

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

Singh, Nagendra; Rao, Sathyanarayan; Ranganath, Praveen

2013-03-15

Experimental measurements have shown that the plasma plume created in a helicon plasma device contains a conical structure in the plasma density and a U-shaped double layer (US-DL) tightly confined near the throat where plasma begins to expand from the source. Recently reported two-dimensional particle-in-cell simulations verified these density and US-DL features of the plasma plume. Simulations also showed that the plasma in the plume develops non-thermal feature consisting of radial ion beams with large densities near the conical surface of the density structure. The plasma waves that are generated by the radial ion beams affecting the structure of themore » plasma plume are studied here. We find that most intense waves persist in the high-density regions of the conical density structure, where the transversely accelerated ions in the radial electric fields in the plume are reflected setting up counter-streaming. The waves generated are primarily ion Bernstein modes. The nonlinear evolution of the waves leads to magnetic field-aligned striations in the fields and the plasma near the conical surface of the density structure.« less

Linear and Nonlinear Response of a Rotating Tokamak Plasma to a Resonant Error-Field

NASA Astrophysics Data System (ADS)

Fitzpatrick, Richard

2014-10-01

An in-depth investigation of the effect of a resonant error-field on a rotating, quasi-cylindrical, tokamak plasma is preformed within the context of resistive-MHD theory. General expressions for the response of the plasma at the rational surface to the error-field are derived in both the linear and nonlinear regimes, and the extents of these regimes mapped out in parameter space. Torque-balance equations are also obtained in both regimes. These equations are used to determine the steady-state plasma rotation at the rational surface in the presence of the error-field. It is found that, provided the intrinsic plasma rotation is sufficiently large, the torque-balance equations possess dynamically stable low-rotation and high-rotation solution branches, separated by a forbidden band of dynamically unstable solutions. Moreover, bifurcations between the two stable solution branches are triggered as the amplitude of the error-field is varied. A low- to high-rotation bifurcation is invariably associated with a significant reduction in the width of the magnetic island chain driven at the rational surface, and vice versa. General expressions for the bifurcation thresholds are derived, and their domains of validity mapped out in parameter space. This research was funded by the U.S. Department of Energy under Contract DE-FG02-04ER-54742.

Impact of cell size on inventory and mapping errors in a cellular geographic information system

NASA Technical Reports Server (NTRS)

Wehde, M. E. (Principal Investigator)

1979-01-01

The author has identified the following significant results. The effect of grid position was found insignificant for maps but highly significant for isolated mapping units. A modelable relationship between mapping error and cell size was observed for the map segment analyzed. Map data structure was also analyzed with an interboundary distance distribution approach. Map data structure and the impact of cell size on that structure were observed. The existence of a model allowing prediction of mapping error based on map structure was hypothesized and two generations of models were tested under simplifying assumptions.

Variability of Protein Structure Models from Electron Microscopy.

PubMed

Monroe, Lyman; Terashi, Genki; Kihara, Daisuke

2017-04-04

An increasing number of biomolecular structures are solved by electron microscopy (EM). However, the quality of structure models determined from EM maps vary substantially. To understand to what extent structure models are supported by information embedded in EM maps, we used two computational structure refinement methods to examine how much structures can be refined using a dataset of 49 maps with accompanying structure models. The extent of structure modification as well as the disagreement between refinement models produced by the two computational methods scaled inversely with the global and the local map resolutions. A general quantitative estimation of deviations of structures for particular map resolutions are provided. Our results indicate that the observed discrepancy between the deposited map and the refined models is due to the lack of structural information present in EM maps and thus these annotations must be used with caution for further applications. Copyright © 2017 Elsevier Ltd. All rights reserved.

Plasma phenomena observed in the MAP/WINE campaign

NASA Technical Reports Server (NTRS)

Friedrich, M.

1989-01-01

The wealth of plasma data gathered in the MAP/WINE campaign allows insight into the generation of electron densities on a large, and the nature of the ions on a small scale. The associated measurements of winds and charged particles help to understand the morphology of the midlatitude ionization which turns out to correlate poorly with geomagnetic activity, but at least slightly with the prevailing winds. A somewhat clearer connection seems to exist between stratospheric warmings and radio wave absorption minima. On the local scale the interpretation of the rocket measurements of positive ions was helped by simultaneous observations of temperatures and atomic oxygen. The relevance of the description winter anomaly for high latitude electron density profiles are examined.

Mapping of native inorganic elements and injected nanoparticles in a biological organ with laser-induced plasma

NASA Astrophysics Data System (ADS)

Motto-Ros, V.; Sancey, L.; Ma, Q. L.; Lux, F.; Bai, X. S.; Wang, X. C.; Yu, Jin; Panczer, G.; Tillement, O.

2012-11-01

Emission spectroscopy of laser-induced plasma from a thin section of mouse kidney successfully detected inorganic elements, Na, Ca, Cu, and Gd, naturally contained in the organ or artificially injected in the form of Gd-based nanoparticle. A two-dimensional scan of the sample allowed the laser beam to explore its surface with a resolution of 100 μm, resulting in a quantitative elemental mapping of the organ with sub-mM sensitivity. The compatibility of the setup with standard optical microscopy emphasizes the potential to provide multiple images of a same biological tissue with different types of response which can be elemental, molecular, or cellular.

Polarization-singular processing of biological layers laser images to diagnose and classify their optical properties

NASA Astrophysics Data System (ADS)

Ushenko, Yu. O.; Telenga, O. Y.

2011-09-01

Presented in this work are the results of investigation aimed at analysis of coordinate distributions for azimuths and ellipticity of polarization (polarization maps) in blood plasma layers laser images of three groups of patients: healthy (group 1), with dysplasia (group 2) and cancer of cervix uteri (group 3). To characterize polarization maps for all groups of samples, the authors have offered to use three groups of parameters: statistical moments of the first to the fourth orders, autocorrelation functions, logarithmic dependences for power spectra related to distributions of azimuths and ellipticity of polarization inherent to blood plasma laser images. Ascertained are the criteria for diagnostics and differentiation of cervix uteri pathological changes.

Mapping the Solar Wind from its Source Region into the Outer Corona

NASA Technical Reports Server (NTRS)

Esser, Ruth

1998-01-01

Knowledge of the radial variation of the plasma conditions in the coronal source region of the solar wind is essential to exploring coronal heating and solar wind acceleration mechanisms. The goal of the present proposal is to determine as many plasma parameters in that region as possible by coordinating different observational techniques, such as Interplanetary Scintillation Observations, spectral line intensity observations, polarization brightness measurements and X-ray observations. The inferred plasma parameters are then used to constrain solar wind models.

Single-Molecule Tracking Photoactivated Localization Microscopy to Map Nano-Scale Structure and Dynamics in Living Spines

PubMed Central

MacGillavry, Harold D.; Blanpied, Thomas A.

2013-01-01

Super-resolution microscopy has rapidly become an indispensable tool in cell biology and neuroscience by enabling measurement in live cells of structures smaller than the classical limit imposed by diffraction. The most widely applied super-resolution method currently is localization microscopy, which takes advantage of the ability to determine the position of individual fluorescent molecules with nanometer accuracy even in cells. By iteratively measuring sparse subsets of photoactivatable fluorescent proteins, protein distribution in macromolecular structures can be accurately reconstructed. Moreover, the motion trajectories of individual molecules within cells can be measured, providing unique ability to measure transport kinetics, exchange rates, and binding affinities of even small subsets of molecules with high temporal resolution and great spatial specificity. This unit describes protocols to measure and quantify the distribution of scaffold proteins within single synapses of cultured hippocampal neurons, and to track and measure the diffusion of intracellular constituents of the neuronal plasma membrane. PMID:25429311

Antiswarming: Structure and dynamics of repulsive chemically active particles

NASA Astrophysics Data System (ADS)

Yan, Wen; Brady, John F.

2017-12-01

Chemically active Brownian particles with surface catalytic reactions may repel each other due to diffusiophoretic interactions in the reaction and product concentration fields. The system behavior can be described by a "chemical" coupling parameter Γc that compares the strength of diffusiophoretic repulsion to Brownian motion, and by a mapping to the classical electrostatic one component plasma (OCP) system. When confined to a constant-volume domain, body-centered cubic (bcc) crystals spontaneously form from random initial configurations when the repulsion is strong enough to overcome Brownian motion. Face-centered cubic (fcc) crystals may also be stable. The "melting point" of the "liquid-to-crystal transition" occurs at Γc≈140 for both bcc and fcc lattices.

Process for forming exoergic structures with the use of a plasma

DOEpatents

Kelly, Michael D.

1989-02-21

A method of forming exoergic structures, as well as exoergic structures produced by the method, is provided. The method comprises the steps of passing a plasma-forming gas through a plasma spray gun, forming a plasma spray, introducing exoergic material into the plasma spray and directing the plasma spray toward a substrate, and allowing the exoergic material to become molten, without chemically reacting in the plasma spray and to thereafter impinge on the substrate to form a solid mass of exoergic material, the shape of which corresponds to the shape of the substrate.

Interstellar heliospheric probe/heliospheric boundary explorer mission—a mission to the outermost boundaries of the solar system

NASA Astrophysics Data System (ADS)

Wimmer-Schweingruber, Robert F.; McNutt, Ralph; Schwadron, Nathan A.; Frisch, Priscilla C.; Gruntman, Mike; Wurz, Peter; Valtonen, Eino

2009-05-01

The Sun, driving a supersonic solar wind, cuts out of the local interstellar medium a giant plasma bubble, the heliosphere. ESA, jointly with NASA, has had an important role in the development of our current understanding of the Suns immediate neighborhood. Ulysses is the only spacecraft exploring the third, out-of-ecliptic dimension, while SOHO has allowed us to better understand the influence of the Sun and to image the glow of interstellar matter in the heliosphere. Voyager 1 has recently encountered the innermost boundary of this plasma bubble, the termination shock, and is returning exciting yet puzzling data of this remote region. The next logical step is to leave the heliosphere and to thereby map out in unprecedented detail the structure of the outer heliosphere and its boundaries, the termination shock, the heliosheath, the heliopause, and, after leaving the heliosphere, to discover the true nature of the hydrogen wall, the bow shock, and the local interstellar medium beyond. This will greatly advance our understanding of the heliosphere that is the best-known example for astrospheres as found around other stars. Thus, IHP/HEX will allow us to discover, explore, and understand fundamental astrophysical processes in the largest accessible plasma laboratory, the heliosphere.

Low-temperature self-limiting atomic layer deposition of wurtzite InN on Si(100)

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

Haider, Ali, E-mail: ali.haider@bilkent.edu.tr, E-mail: biyikli@unam.bilkent.edu.tr; Kizir, Seda; Biyikli, Necmi, E-mail: ali.haider@bilkent.edu.tr, E-mail: biyikli@unam.bilkent.edu.tr

2016-04-15

In this work, we report on self-limiting growth of InN thin films at substrate temperatures as low as 200 °C by hollow-cathode plasma-assisted atomic layer deposition (HCPA-ALD). The precursors used in growth experiments were trimethylindium (TMI) and N{sub 2} plasma. Process parameters including TMI pulse time, N{sub 2} plasma exposure time, purge time, and deposition temperature have been optimized for self-limiting growth of InN with in ALD window. With the increase in exposure time of N{sub 2} plasma from 40 s to 100 s at 200 °C, growth rate showed a significant decrease from 1.60 to 0.64 Å/cycle. At 200 °C, growth ratemore » saturated as 0.64 Å/cycle for TMI dose starting from 0.07 s. Structural, optical, and morphological characterization of InN were carried out in detail. X-ray diffraction measurements revealed the hexagonal wurtzite crystalline structure of the grown InN films. Refractive index of the InN film deposited at 200 °C was found to be 2.66 at 650 nm. 48 nm-thick InN films exhibited relatively smooth surfaces with Rms surface roughness values of 0.98 nm, while the film density was extracted as 6.30 g/cm{sup 3}. X-ray photoelectron spectroscopy (XPS) measurements depicted the peaks of indium, nitrogen, carbon, and oxygen on the film surface and quantitative information revealed that films are nearly stoichiometric with rather low impurity content. In3d and N1s high-resolution scans confirmed the presence of InN with peaks located at 443.5 and 396.8 eV, respectively. Transmission electron microscopy (TEM) and selected area electron diffraction (SAED) further confirmed the polycrystalline structure of InN thin films and elemental mapping revealed uniform distribution of indium and nitrogen along the scanned area of the InN film. Spectral absorption measurements exhibited an optical band edge around 1.9 eV. Our findings demonstrate that HCPA-ALD might be a promising technique to grow crystalline wurtzite InN thin films at low substrate temperatures.« less

NOS II inhibition attenuates post-suspension hypotension in Sprague-Dawley rats

NASA Technical Reports Server (NTRS)

Eatman, D.; Walton, M.; Socci, R. R.; Emmett, N.; Bayorh, M. A.

2003-01-01

The reduction in mean arterial pressure observed in astronauts may be related to the impairment of autonomic function and/or excessive production of endothelium-derived relaxing factors. Here, we examined the role of a nitric oxide synthase II (NOS II) inhibitor AMT (2-amino-dihydro-6-methyl-4H-1,3-thiazine) against the post-suspension reduction in mean arterial pressure (MAP) in conscious male Sprague-Dawley rats. Direct MAP and heart rate were determined prior to tail-suspension, daily during the 7-day suspension and every 2 hrs post-suspension. Prior to release from suspension and at 2 and 4 hrs post-suspension, AMT (0.1 mg/kg), or saline, were administered intravenously. During the 7-day suspension, MAP was not altered, nor were there significant changes in heart rate. The reduction in MAP post-suspension in saline-treated rats was associated with significant increases in plasma nitric oxide and prostacyclin. 2-Amino-dihydro-6-methyl4H-1,3-thiazine reduced plasma nitric oxide levels, but not those of prostacyclin, attenuated the observed post-suspension reduction in MAP and modified the baroreflex sensitivity for heart rate. Thus, the post suspension reduction in mean arterial pressure is due, in part, to overproduction of nitric oxide, via the NOS II pathway, and alteration in baroreflex activity.

2D elemental mapping of sections of human kidney stones using laser ablation inductively-coupled plasma-mass spectrometry: Possibilities and limitations

NASA Astrophysics Data System (ADS)

Vašinová Galiová, Michaela; Čopjaková, Renata; Škoda, Radek; Štěpánková, Kateřina; Vaňková, Michaela; Kuta, Jan; Prokeš, Lubomír; Kynický, Jindřich; Kanický, Viktor

2014-10-01

A 213 nm Nd:YAG-based laser ablation (LA) system coupled to quadrupole-based inductively coupled plasma-mass spectrometer and an ArF* excimer-based LA-system coupled to a double-focusing sector field inductively coupled plasma-mass spectrometer were employed to study the spatial distribution of various elements in kidney stones (uroliths). Sections of the surfaces of uroliths were ablated according to line patterns to investigate the elemental profiles for the different urolith growth zones. This exploratory study was mainly focused on the distinguishing of the main constituents of urinary calculus fragments by means of LA-ICP-mass spectrometry. Changes in the ablation rate for oxalate and phosphate phases related to matrix density and hardness are discussed. Elemental association was investigated on the basis of 2D mapping. The possibility of using NIST SRM 1486 Bone Meal as an external standard for calibration was tested. It is shown that LA-ICP-MS is helpful for determination of the mineralogical composition and size of all phases within the analyzed surface area, for tracing down elemental associations and for documenting the elemental content of urinary stones. LA-ICP-MS results (elemental contents and maps) are compared to those obtained with electron microprobe analysis and solution analysis ICP-MS.

Using Concept Maps to Monitor Knowledge Structure Changes in a Science Classroom

NASA Astrophysics Data System (ADS)

Cook, Leah J.

The aim of this research is to determine what differences may exist in students' structural knowledge while using a variety of concept mapping assessments. A concept map can be used as an assessment which connects concepts in a knowledge domain. A single assessment may not be powerful enough to establish how students' new knowledge relates to prior knowledge. More research is needed to establish how various aspects of the concept mapping task influence the output of map creation by students. Using multiple concept maps and pre-instruction and post-instruction VNOS instruments during a 16-week semester, this study was designed to investigate the impact of concept map training and the impact of assessment design on the created maps. Also, this study was designed to determine what differences can be observed between expert and novice maps and if similarities and differences exist between concept maps and an open-ended assessment. Participants created individual maps and the maps were analyzed for structural complexity, overall structure, and content. The concept maps were then compared by their timing, design, and scores. The results indicate that concept mapping training does significantly impact the shape and structure complexity of the map created by students. Additionally, these data support that students should be frequently reminded of appropriate concept mapping skills and opportunities so that good mapping skills will be utilized. Changing the assessment design does appear to be able to impact the overall structure and complexity of created maps, while narrowing the content focus of the map does not necessarily restrict the overall structure or the complexity. Furthermore, significant differences in structural complexity were observed between novice and expert mappers. The fluctuations of NOS concepts identified in student created maps may suggest why some students were still confused or had incorrect conceptions of NOS, despite explicit and reflective instruction throughout the semester.

Laboratory simulation of the interaction between a tethered satellite system and the ionosphere

NASA Astrophysics Data System (ADS)

Vannaroni, G.; Giovi, R.; de Venuto, F.

1992-10-01

The authors report on the measurements performed in the IFSI/CNR plasma chamber at Frascati related to the laboratory investigation of the interaction between a plasma source and an ambient plasma of ionospheric type. Such an interaction is of relevant interest for the possibility of using electrodynamic tethered satellite systems, orbiting at ionospheric altitude, for generating electric power or propulsion in space. The interaction region was analyzed at various conditions of ambient magnetic field (/0-0.5/ G) and at different polarization levels of the plasma source (/0-40/ V). The plasma measurements were carried out with a diagnostic system using an array of Langmuir probes movable in the chamber so that a map of the plasma parameters could be obtained at the different experimental conditions.

Common Missense Variant in the Glucokinase Regulatory Protein Gene Is Associated With Increased Plasma Triglyceride and C-Reactive Protein but Lower Fasting Glucose Concentrations

PubMed Central

Orho-Melander, Marju; Melander, Olle; Guiducci, Candace; Perez-Martinez, Pablo; Corella, Dolores; Roos, Charlotta; Tewhey, Ryan; Rieder, Mark J.; Hall, Jennifer; Abecasis, Goncalo; Tai, E. Shyong; Welch, Cullan; Arnett, Donna K.; Lyssenko, Valeriya; Lindholm, Eero; Saxena, Richa; de Bakker, Paul I.W.; Burtt, Noel; Voight, Benjamin F.; Hirschhorn, Joel N.; Tucker, Katherine L.; Hedner, Thomas; Tuomi, Tiinamaija; Isomaa, Bo; Eriksson, Karl-Fredrik; Taskinen, Marja-Riitta; Wahlstrand, Björn; Hughes, Thomas E.; Parnell, Laurence D.; Lai, Chao-Qiang; Berglund, Göran; Peltonen, Leena; Vartiainen, Erkki; Jousilahti, Pekka; Havulinna, Aki S.; Salomaa, Veikko; Nilsson, Peter; Groop, Leif; Altshuler, David; Ordovas, Jose M.; Kathiresan, Sekar

2008-01-01

OBJECTIVE—Using the genome-wide association approach, we recently identified the glucokinase regulatory protein gene (GCKR, rs780094) region as a novel quantitative trait locus for plasma triglyceride concentration in Europeans. Here, we sought to study the association of GCKR variants with metabolic phenotypes, including measures of glucose homeostasis, to evaluate the GCKR locus in samples of non-European ancestry and to fine- map across the associated genomic interval. RESEARCH DESIGN AND METHODS—We performed association studies in 12 independent cohorts comprising >45,000 individuals representing several ancestral groups (whites from Northern and Southern Europe, whites from the U.S., African Americans from the U.S., Hispanics of Caribbean origin, and Chinese, Malays, and Asian Indians from Singapore). We conducted genetic fine-mapping across the ∼417-kb region of linkage disequilibrium spanning GCKR and 16 other genes on chromosome 2p23 by imputing untyped HapMap single nucleotide polymorphisms (SNPs) and genotyping 104 SNPs across the associated genomic interval. RESULTS—We provide comprehensive evidence that GCKR rs780094 is associated with opposite effects on fasting plasma triglyceride (Pmeta = 3 × 10−56) and glucose (Pmeta = 1 × 10−13) concentrations. In addition, we confirmed recent reports that the same SNP is associated with C-reactive protein (CRP) level (P = 5 × 10−5). Both fine-mapping approaches revealed a common missense GCKR variant (rs1260326, Pro446Leu, 34% frequency, r2 = 0.93 with rs780094) as the strongest association signal in the region. CONCLUSIONS—These findings point to a molecular mechanism in humans by which higher triglycerides and CRP can be coupled with lower plasma glucose concentrations and position GCKR in central pathways regulating both hepatic triglyceride and glucose metabolism. PMID:18678614

Automated identification and tracking of polar-cap plasma patches at solar minimum

NASA Astrophysics Data System (ADS)

Burston, R.; Hodges, K.; Astin, I.; Jayachandran, P. T.

2014-03-01

A method of automatically identifying and tracking polar-cap plasma patches, utilising data inversion and feature-tracking methods, is presented. A well-established and widely used 4-D ionospheric imaging algorithm, the Multi-Instrument Data Assimilation System (MIDAS), inverts slant total electron content (TEC) data from ground-based Global Navigation Satellite System (GNSS) receivers to produce images of the free electron distribution in the polar-cap ionosphere. These are integrated to form vertical TEC maps. A flexible feature-tracking algorithm, TRACK, previously used extensively in meteorological storm-tracking studies is used to identify and track maxima in the resulting 2-D data fields. Various criteria are used to discriminate between genuine patches and "false-positive" maxima such as the continuously moving day-side maximum, which results from the Earth's rotation rather than plasma motion. Results for a 12-month period at solar minimum, when extensive validation data are available, are presented. The method identifies 71 separate structures consistent with patch motion during this time. The limitations of solar minimum and the consequent small number of patches make climatological inferences difficult, but the feasibility of the method for patches larger than approximately 500 km in scale is demonstrated and a larger study incorporating other parts of the solar cycle is warranted. Possible further optimisation of discrimination criteria, particularly regarding the definition of a patch in terms of its plasma concentration enhancement over the surrounding background, may improve results.

Diagnostics of Plasma Propulsion Devices

NASA Astrophysics Data System (ADS)

Cappelli, Mark A.

1998-11-01

Plasma rockets are rapidly emerging as critical technologies in future space flight. These devices take on various forms, ranging from electro-thermal to electromagnetic accelerators, generally categorized by the method in which electrical energy is converted to thrust. As is the case in many plasma devices, non-intrusive optical (emission, or laser-based) diagnostics is an essential element in the characterization of these plasma sources, as access to the discharges in these plasma engines is often limited. Furthermore, laser-based diagnostics offer additional benefits, including improved spatial resolution, and can provide state-specific measurements of species densities, velocities and energy distributions. In recent years, we have developed and applied a variety of emission and laser-based diagnostics strategies to the characterization of arcjet plasma and closed-drift xenon Hall plasma accelerators. Both of these types of plasma propulsion devices are of immediate interest to the space propulsion community, and are under varying stages of development. Arcjet thrusters have unique properties, with strong plasma density, temperature and velocity gradients, which enhance the coupling between the gasdynamic and plasma physics. Closed-drift Hall plasma thrusters are low density electrostatic devices that are inherently turbulent, and exhibit varying degrees of anomalous cross-field electron transport. Our most extensive, collective effort has been to apply laser-induced fluorescence, Doppler-free laser absorption, and Raman scattering to the characterization of hydrogen and helium arcjet flows. Detailed measurements of velocity, temperatures, and electron densities are compared to the results of magneto-hydrodynamic flowfield simulations. The results show that while the simulations capture many aspects of the flow, there are still some unresolved discrepancies. The database established for Hall thrusters is less extensive, as the laser absorption spectroscopy of xenon is somewhat more complicated due to the hyperfine and isotopic structure of electronic transitions. With an understanding of the spectroscopic absorption lineshape for two select transitions in neutral and ionized xenon, we have successfully mapped out the neutral and singly ionized xenon velocities in the acceleration zone of Hall thrusters. These results indicate that the acceleration zone in a short-channel thruster is outside of the device, consistent with the measurements of plasma potential using more conventional Langmuir electrostatic probes. The spectroscopic data has also been used to identify limitations in ground-test facilities.

MAP3K8 (TPL2/COT) affects obesity-induced adipose tissue inflammation without systemic effects in humans and in mice.

PubMed

Ballak, Dov B; van Essen, Peter; van Diepen, Janna A; Jansen, Henry; Hijmans, Anneke; Matsuguchi, Tetsuya; Sparrer, Helmut; Tack, Cees J; Netea, Mihai G; Joosten, Leo A B; Stienstra, Rinke

2014-01-01

Chronic low-grade inflammation in adipose tissue often accompanies obesity, leading to insulin resistance and increasing the risk for metabolic diseases. MAP3K8 (TPL2/COT) is an important signal transductor and activator of pro-inflammatory pathways that has been linked to obesity-induced adipose tissue inflammation. We used human adipose tissue biopsies to study the relationship of MAP3K8 expression with markers of obesity and expression of pro-inflammatory cytokines (IL-1β, IL-6 and IL-8). Moreover, we evaluated obesity-induced adipose tissue inflammation and insulin resistance in mice lacking MAP3K8 and WT mice on a high-fat diet (HFD) for 16 weeks. Individuals with a BMI >30 displayed a higher mRNA expression of MAP3K8 in adipose tissue compared to individuals with a normal BMI. Additionally, high mRNA expression levels of IL-1β, IL-6 and IL-8, but not TNF -α, in human adipose tissue were associated with higher expression of MAP3K8. Moreover, high plasma SAA and CRP did not associate with increased MAP3K8 expression in adipose tissue. Similarly, no association was found for MAP3K8 expression with plasma insulin or glucose levels. Mice lacking MAP3K8 had similar bodyweight gain as WT mice, yet displayed lower mRNA expression levels of IL-1β, IL-6 and CXCL1 in adipose tissue in response to the HFD as compared to WT animals. However, MAP3K8 deficient mice were not protected against HFD-induced adipose tissue macrophage infiltration or the development of insulin resistance. Together, the data in both human and mouse show that MAP3K8 is involved in local adipose tissue inflammation, specifically for IL-1β and its responsive cytokines IL-6 and IL-8, but does not seem to have systemic effects on insulin resistance.

Computational methods for constructing protein structure models from 3D electron microscopy maps.

PubMed

Esquivel-Rodríguez, Juan; Kihara, Daisuke

2013-10-01

Protein structure determination by cryo-electron microscopy (EM) has made significant progress in the past decades. Resolutions of EM maps have been improving as evidenced by recently reported structures that are solved at high resolutions close to 3Å. Computational methods play a key role in interpreting EM data. Among many computational procedures applied to an EM map to obtain protein structure information, in this article we focus on reviewing computational methods that model protein three-dimensional (3D) structures from a 3D EM density map that is constructed from two-dimensional (2D) maps. The computational methods we discuss range from de novo methods, which identify structural elements in an EM map, to structure fitting methods, where known high resolution structures are fit into a low-resolution EM map. A list of available computational tools is also provided. Copyright © 2013 Elsevier Inc. All rights reserved.

The Role of the Auroral Processes in the Formation of the Outer Electron Radiation Belt

NASA Astrophysics Data System (ADS)

Stepanova, M. V.; Antonova, E. E.; Pinto, V. A.; Moya, P. S.; Riazantseva, M.; Ovchinnikov, I.

2016-12-01

The role of the auroral processes in the formation of the outer electron radiation belt during storms is analyzed using the data of RBSP mission, low orbiting satellites and ground based observations. We analyze fluxes of the low energy precipitating ions using data of the Defense Meteorological Satellite Program (DMSP). The location of the auroral electrojet is obtained from the IMAGE magnetometer network, and of the electron distribution in the outer radiation belt from the RBSP mission. We take into account the latest results on the auroral oval mapping in accordance with which the most part of the auroral oval maps not to the plasma sheet. It maps into the surrounding the Earth plasma ring in which transverse currents are closed inside the magnetosphere. Such currents constitute the high latitude continuation of the ordinary ring current. The development of the ring current and its high latitude continuation generates strong distortion of the Earth's magnetic field and corresponding adiabatic variation of the relativistic electron fluxes. This adiabatic variation should be considered for the analysis of the processes of the acceleration of relativistic electrons and formation of the outer radiation belt. We also analyze the plasma pressure profiles during storms and demonstrate the formation of sharp plasma pressure peak at the equatorial boundary of the auroral oval. It is shown that the observed this peak is directly connected to the creation of the seed population of relativistic electrons. We discuss the possibility to predict the position of new radiation belt during recovery phase of the magnetic storm using data of low orbiting and ground based observations.

A finite element method with overlapping meshes for free-boundary axisymmetric plasma equilibria in realistic geometries

NASA Astrophysics Data System (ADS)

Heumann, Holger; Rapetti, Francesca

2017-04-01

Existing finite element implementations for the computation of free-boundary axisymmetric plasma equilibria approximate the unknown poloidal flux function by standard lowest order continuous finite elements with discontinuous gradients. As a consequence, the location of critical points of the poloidal flux, that are of paramount importance in tokamak engineering, is constrained to nodes of the mesh leading to undesired jumps in transient problems. Moreover, recent numerical results for the self-consistent coupling of equilibrium with resistive diffusion and transport suggest the necessity of higher regularity when approximating the flux map. In this work we propose a mortar element method that employs two overlapping meshes. One mesh with Cartesian quadrilaterals covers the vacuum chamber domain accessible by the plasma and one mesh with triangles discretizes the region outside. The two meshes overlap in a narrow region. This approach gives the flexibility to achieve easily and at low cost higher order regularity for the approximation of the flux function in the domain covered by the plasma, while preserving accurate meshing of the geometric details outside this region. The continuity of the numerical solution in the region of overlap is weakly enforced by a mortar-like mapping.

Nonlinear Optical Interactions in Plasmas at JILA

NASA Astrophysics Data System (ADS)

Dollar, F.; Hickstein, D. D.; Popmintchev, D.; Becker, A.; Ellis, J.; Hernandez-Garcia, C.; Jaron-Becker, A.; Popmintchev, T.; Xiong, W.; Murnane, M. M.; Kapteyn, H. C.; Dukovic, G.; Jimenez, J.; Palm, B.; Schnitzenbaumer, K.; Perez-Hernandez, J.; Gaeta, A.; Gao, X.; Shim, B.; Plaja, L.; Levis, R.; Tarazkar, M.; Foord, M. E.; Gaffney, J. A.; Libby, S. B.

2014-10-01

We present data from two recent experiments. First, we demonstrate direct observations of localized light absorption in a single nanoparticle irradiated by a strong femtosecond laser field. By imaging the photoion momentum distribution resulting from plasma formation in a laser-irradiated nanostructure, we map the spatial location of the highly localized plasma and thereby image the nanoscale light absorption. Secondly, we show the high linear and nonlinear UV refractive indices of both neutral atoms and ions compensate for plasma dispersion, even in multiply-ionized gases. The experimental work was primarily funded by DOE Grant Number: DE-SC0008803, the DARPA PULSE program, and ARO W911NF-12-1-0436.

Effectiveness of recycling light in ultra-bright short-arc discharge lamps.

PubMed

Malul, Asher; Nakar, Doron; Feuermann, Daniel; Gordon, Jeffrey M

2007-10-17

Recycling light back into a plasma lamp's radiant zone can enhance its radiance. Measurements are reported for the effectiveness, spectral properties and modified plasma radiance maps that result from light recycling with a specular hemispherical mirror in commercial 150 W ultrabright Xenon short-arc discharge lamps, motivated by projection, biomedical and high-temperature furnace applications. For certain spectral windows and plasma arc regions, radiance can be heightened by up to 70%. However, the overall light recycling efficiency is reduced to about half this value due to lamp geometry. The manner in which light-plasma interactions affect light recycling efficacy is also elucidated.

Study of plasma-based stable and ultra-wideband electromagnetic wave absorption for stealth application

NASA Astrophysics Data System (ADS)

Xuyang, CHEN; Fangfang, SHEN; Yanming, LIU; Wei, AI; Xiaoping, LI

2018-06-01

A plasma-based stable, ultra-wideband electromagnetic (EM) wave absorber structure is studied in this paper for stealth applications. The stability is maintained by a multi-layer structure with several plasma layers and dielectric layers distributed alternately. The plasma in each plasma layer is designed to be uniform, whereas it has a discrete nonuniform distribution from the overall view of the structure. The nonuniform distribution of the plasma is the key to obtaining ultra-wideband wave absorption. A discrete Epstein distribution model is put forward to constrain the nonuniform electron density of the plasma layers, by which the wave absorption range is extended to the ultra-wideband. Then, the scattering matrix method (SMM) is employed to analyze the electromagnetic reflection and absorption of the absorber structure. In the simulation, the validation of the proposed structure and model in ultra-wideband EM wave absorption is first illustrated by comparing the nonuniform plasma model with the uniform case. Then, the influence of various parameters on the EM wave reflection of the plasma are simulated and analyzed in detail, verifying the EM wave absorption performance of the absorber. The proposed structure and model are expected to be superior in some realistic applications, such as supersonic aircraft.

Theory of Parabolic Arcs in Interstellar Scintillation Spectra

NASA Astrophysics Data System (ADS)

Cordes, James M.; Rickett, Barney J.; Stinebring, Daniel R.; Coles, William A.

2006-01-01

Interstellar scintillation (ISS), observed as time variation in the intensity of a compact radio source, is caused by small-scale structure in the electron density of the interstellar plasma. Dynamic spectra of ISS show modulation in radio frequency and time. Here we relate the (two-dimensional) power spectrum of the dynamic spectrum-the secondary spectrum-to the scattered image of the source. Recent work has identified remarkable parabolic arcs in secondary spectra. Each point in a secondary spectrum corresponds to interference between points in the scattered image with a certain Doppler shift and a certain delay. The parabolic arc corresponds to the quadratic relation between differential Doppler shift and delay through their common dependence on scattering angle. We show that arcs will occur in all media that scatter significant power at angles larger than the rms angle. Thus, effects such as source diameter, steep spectra, and dissipation scales, which truncate high angle scattering, also truncate arcs. Arcs are equally visible in simulations of nondispersive scattering. They are enhanced by anisotropic scattering when the spatial structure is elongated perpendicular to the velocity. In weak scattering the secondary spectrum is directly mapped from the scattered image, and this mapping can be inverted. We discuss additional observed phenomena including multiple arcs and reverse arclets oriented oppositely to the main arc. These phenomena persist for many refractive scattering times, suggesting that they are due to large-scale density structures, rather than low-frequency components of Kolmogorov turbulence.

Coronal magnetic structures observing campaign. I - Simultaneous microwave and soft X-ray observations of active regions at the solar limb

NASA Astrophysics Data System (ADS)

Nitta, N.; White, S. M.; Kundu, M. R.; Gopalswamy, N.; Holman, G. D.; Brosius, J. W.; Schmelz, J. T.; Saba, J. L. R.; Strong, K. T.

1991-06-01

Using simultaneous microwave and soft X-ray measurements made with the Very Large Array (VLA) at 6 and 20 cm and the X-ray Polychromator (XRP) aboard the Solar Maximum Mission (SMM), we have studied two active regions near the solar limb. These observations were taken as part of the Coronal Magnetic Structures Observing Campaign (CoMStOC), a collaboration designed to study the magnetic field in the solar corona. The images in soft X-rays and at 20 cm wavelength are similar: both show peaks above the active regions and extended bridge of emission 200,000 km long connecting the two regions. The brightness temperature of the 20 cm emission is lower than that predicted from the X-ray emitting material, however; it can be attributed to free-free emission in cooler (<106 K) plasma not visible to XRP, with an optical depth ˜1. The 6 cm emission is concentrated at lower altitudes and in a ˜160,000 km long bundle of loops in the northern active region. Comparison of the 6 cm map with the potential magnetic field lines computed from photospheric magnetic fields (measured 2 days earlier) indicates that the 6 cm emission is associated with fields of less than ˜200 G. Such fields would be too weak to attribute the observed 6 cm emission to gyroresonance radiation. Analysis of the 6 cm loop bundle indicates that it is strongly asymmetric, with the magnetic field in the northern leg ˜2 times stronger than in the southern leg; the 6 cm emission most likely arises from a combination of hot ( ≥ 2 × 106 K) and cool plasmas, while the 20 cm emission becomes optically thick in the cooler (˜9 × 103 K) plasma. We estimate an Alfvén speed ˜7000 km s-1 and ratio of electron gyrofrequency to plasma frequency ˜1.0 in the northern leg of the 6 cm loop.

Selenium Accumulation, Distribution, and Speciation in Spineless Prickly Pear Cactus: A Drought- and Salt-Tolerant, Selenium-Enriched Nutraceutical Fruit Crop for Biofortified Foods1[OA

PubMed Central

Bañuelos, Gary S.; Fakra, Sirine C.; Walse, Spencer S.; Marcus, Matthew A.; Yang, Soo In; Pickering, Ingrid J.; Pilon-Smits, Elizabeth A.H.; Freeman, John L.

2011-01-01

The organ-specific accumulation, spatial distribution, and chemical speciation of selenium (Se) were previously unknown for any species of cactus. We investigated Se in Opuntia ficus-indica using inductively coupled plasma mass spectrometry, microfocused x-ray fluorescence elemental and chemical mapping (μXRF), Se K-edge x-ray absorption near-edge structure (XANES) spectroscopy, and liquid chromatography-mass spectrometry (LC-MS). μXRF showed Se concentrated inside small conic, vestigial leaves (cladode tips), the cladode vasculature, and the seed embryos. Se K-edge XANES demonstrated that approximately 96% of total Se in cladode, fruit juice, fruit pulp, and seed is carbon-Se-carbon (C-Se-C). Micro and bulk XANES analysis showed that cladode tips contained both selenate and C-Se-C forms. Inductively coupled plasma mass spectrometry quantification of Se in high-performance liquid chromatography fractions followed by LC-MS structural identification showed selenocystathionine-to-selenomethionine (SeMet) ratios of 75:25, 71:29, and 32:68, respectively in cladode, fruit, and seed. Enzymatic digestions and subsequent analysis confirmed that Se was mainly present in a “free” nonproteinaceous form inside cladode and fruit, while in the seed, Se was incorporated into proteins associated with lipids. μXRF chemical mapping illuminated the specific location of Se reduction and assimilation from selenate accumulated in the cladode tips into the two LC-MS-identified C-Se-C forms before they were transported into the cladode mesophyll. We conclude that Opuntia is a secondary Se-accumulating plant whose fruit and cladode contain mostly free selenocystathionine and SeMet, while seeds contain mainly SeMet in protein. When eaten, the organic Se forms in Opuntia fruit, cladode, and seed may improve health, increase Se mineral nutrition, and help prevent multiple human cancers. PMID:21059825

Selenium Accumulation, Distribution, and Speciation in Spineless Prickly Pear Cactus: A Drought- and Salt-Tolerant, Selenium-Enriched Nutraceutical Fruit Crop for Biofortified Foods

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

Banuelos, Gary S.; Fakra, Sirine C.; Walse, Spencer S.

The organ-specific accumulation, spatial distribution, and chemical speciation of selenium (Se) were previously unknown for any species of cactus. We investigated Se in Opuntia ficus-indica using inductively coupled plasma mass spectrometry, microfocused x-ray fluorescence elemental and chemical mapping ({micro}XRF), Se K-edge x-ray absorption near-edge structure (XANES) spectroscopy, and liquid chromatography-mass spectrometry (LC-MS). {micro}XRF showed Se concentrated inside small conic, vestigial leaves (cladode tips), the cladode vasculature, and the seed embryos. Se K-edge XANES demonstrated that approximately 96% of total Se in cladode, fruit juice, fruit pulp, and seed is carbon-Se-carbon (C-Se-C). Micro and bulk XANES analysis showed that cladode tipsmore » contained both selenate and C-Se-C forms. Inductively coupled plasma mass spectrometry quantification of Se in high-performance liquid chromatography fractions followed by LC-MS structural identification showed selenocystathionine-to-selenomethionine (SeMet) ratios of 75:25, 71:29, and 32:68, respectively in cladode, fruit, and seed. Enzymatic digestions and subsequent analysis confirmed that Se was mainly present in a 'free' nonproteinaceous form inside cladode and fruit, while in the seed, Se was incorporated into proteins associated with lipids. {micro}XRF chemical mapping illuminated the specific location of Se reduction and assimilation from selenate accumulated in the cladode tips into the two LC-MS-identified C-Se-C forms before they were transported into the cladode mesophyll. We conclude that Opuntia is a secondary Se-accumulating plant whose fruit and cladode contain mostly free selenocystathionine and SeMet, while seeds contain mainly SeMet in protein. When eaten, the organic Se forms in Opuntia fruit, cladode, and seed may improve health, increase Se mineral nutrition, and help prevent multiple human cancers.« less

An investigation of plasma enhanced combustion

NASA Astrophysics Data System (ADS)

Kim, Woo Kyung

This study examines the use of plasma discharges in flame stabilization. Three different types of plasma discharges are applied to a lifted jet diffusion flame in coflow, and evaluated for their abilities to enhance flame stabilization. A single electrode corona discharge (SECD) is found to maintain the flame at a 20 % higher coflow speed than that without the discharge. A dielectric barrier discharge (DBD) results in flame stabilization at up to 50 % higher coflow speed. Finally, an ultra short-pulsed repetitive discharge (USRD) is found to increase the stability limit by nearly ten-fold. The stabilization process is sensitive to the positioning of the discharge in the flow field, and the optimal position of the discharge is mapped into mixture fraction space. The result shows that the local mixture fraction at the optimal position is much leaner than that of a conventional lifted jet flame. Parametric studies are conducted in a plasma-assisted methane/air premixed flame system using USRD. Criteria for optimal electrode selection are suggested. Platinum provides the best result at low frequency operation (< 20 kHz) but tungsten shows better performance at high frequency operation (> 20 kHz). The increase in the flame stability limit is also investigated. The flame stability limit extends from an equivalence ratio of 0.7 to 0.47. Nitric oxide (NO) concentration in the premixed flame is measured. The discharge is a potential source of NO. Under certain conditions, we observed the presence of a cold pre-flame, located between the discharge and the main flame. It is found that the pre-flame partially consumes some NO. The flame kernel structure and ignition mechanism of plasma-assisted premixed combustion are discussed. It is observed that the pre-flame has an abundance of OH radicals. The key physics of the flame ignition is the diffusion of an OH stream (from the pre-flame) into the surrounding combustible mixture to form the main flame. Lastly, the proposed flame kernel structure is numerically validated using the OPPDIF code. The simulation shows that possibly three reaction zones, one pre-flame and two main flames, exist in this flame configuration.

Ultrafast molecular processes mapped by femtosecond x-ray diffraction

NASA Astrophysics Data System (ADS)

Elsaesser, Thomas

2012-02-01

X-ray diffraction with a femtosecond time resolution allows for mapping photoinduced structural dynamics on the length scale of a chemical bond and in the time domain of atomic and molecular motion. In a pump-probe approach, a femtosecond excitation pulse induces structural changes which are probed by diffracting a femtosecond hard x-ray pulse from the excited sample. The transient angular positions and intensities of diffraction peaks give insight into the momentary atomic or molecular positions and into the distribution of electronic charge density. The simultaneous measurement of changes on different diffraction peaks is essential for determining atom positions and charge density maps with high accuracy. Recent progress in the generation of ultrashort hard x-ray pulses (Cu Kα, wavelength λ=0.154 nm) in laser-driven plasma sources has led to the implementation of the powder diffraction and the rotating crystal method with a time resolution of 100 fs. In this contribution, we report new results from powder diffraction studies of molecular materials. A first series of experiments gives evidence of a so far unknown concerted transfer of electrons and protons in ammonium sulfate [(NH4)2SO4], a centrosymmetric structure. Charge transfer from the sulfate groups results in the sub-100 fs generation of a confined electron channel along the c-axis of the unit cell which is stabilized by transferring protons from the adjacent ammonium groups into the channel. Time-dependent charge density maps display a periodic modulation of the channel's charge density by low-frequency lattice motions with a concerted electron and proton motion between the channel and the initial proton binding site. A second study addresses atomic rearrangements and charge dislocations in the non-centrosymmetric potassium dihydrogen phosphate [KH2PO4, KDP]. Photoexcitation generates coherent low-frequency motions along the LO and TO phonon coordinates, leaving the average atomic positions unchanged. The time-dependent maps of electron density demonstrate a concomitant oscillatory relocation of electronic charge with a spatial amplitude of the order of a chemical bond length, two orders of magnitude larger than the vibrational amplitudes. The coherent phonon motions drive the charge relocation, similar to a soft mode driven phase transition between the ferro- and paraelectric phase of KDP.

Spatial proximity effects on the excitation of sheath RF voltages by evanescent slow waves in the ion cyclotron range of frequencies

NASA Astrophysics Data System (ADS)

Colas, Laurent; Lu, Ling-Feng; Křivská, Alena; Jacquot, Jonathan; Hillairet, Julien; Helou, Walid; Goniche, Marc; Heuraux, Stéphane; Faudot, Eric

2017-02-01

We investigate theoretically how sheath radio-frequency (RF) oscillations relate to the spatial structure of the near RF parallel electric field E ∥ emitted by ion cyclotron (IC) wave launchers. We use a simple model of slow wave (SW) evanescence coupled with direct current (DC) plasma biasing via sheath boundary conditions in a 3D parallelepiped filled with homogeneous cold magnetized plasma. Within a ‘wide-sheath’ asymptotic regime, valid for large-amplitude near RF fields, the RF part of this simple RF  +  DC model becomes linear: the sheath oscillating voltage V RF at open field line boundaries can be re-expressed as a linear combination of individual contributions by every emitting point in the input field map. SW evanescence makes individual contributions all the larger as the wave emission point is located closer to the sheath walls. The decay of |V RF| with the emission point/sheath poloidal distance involves the transverse SW evanescence length and the radial protrusion depth of lateral boundaries. The decay of |V RF| with the emitter/sheath parallel distance is quantified as a function of the parallel SW evanescence length and the parallel connection length of open magnetic field lines. For realistic geometries and target SOL plasmas, poloidal decay occurs over a few centimeters. Typical parallel decay lengths for |V RF| are found to be smaller than IC antenna parallel extension. Oscillating sheath voltages at IC antenna side limiters are therefore mainly sensitive to E ∥ emission by active or passive conducting elements near these limiters, as suggested by recent experimental observations. Parallel proximity effects could also explain why sheath oscillations persist with antisymmetric strap toroidal phasing, despite the parallel antisymmetry of the radiated field map. They could finally justify current attempts at reducing the RF fields induced near antenna boxes to attenuate sheath oscillations in their vicinity.

Characteristics of equatorial plasma bubbles observed by TEC map based on ground-based GNSS receivers over South America

NASA Astrophysics Data System (ADS)

Barros, Diego; Takahashi, Hisao; Wrasse, Cristiano M.; Figueiredo, Cosme Alexandre O. B.

2018-01-01

A ground-based network of GNSS receivers has been used to monitor equatorial plasma bubbles (EPBs) by mapping the total electron content (TEC map). The large coverage of the TEC map allowed us to monitor several EPBs simultaneously and get characteristics of the dynamics, extension and longitudinal distributions of the EPBs from the onset time until their disappearance. These characteristics were obtained by using TEC map analysis and the keogram technique. TEC map databases analyzed were for the period between November 2012 and January 2016. The zonal drift velocities of the EPBs showed a clear latitudinal gradient varying from 123 m s-1 at the Equator to 65 m s-1 for 35° S latitude. Consequently, observed EPBs are inclined against the geomagnetic field lines. Both zonal drift velocity and the inclination of the EPBs were compared to the thermospheric neutral wind, which showed good agreement. Moreover, the large two-dimensional coverage of TEC maps allowed us to study periodic EPBs with a wide longitudinal distance. The averaged values observed for the inter-bubble distances also presented a clear latitudinal gradient varying from 920 km at the Equator to 640 km at 30° S. The latitudinal gradient in the inter-bubble distances seems to be related to the difference in the zonal drift velocity of the EPB from the Equator to middle latitudes and to the difference in the westward movement of the terminator. On several occasions, the distances reached more than 2000 km. Inter-bubble distances greater than 1000 km have not been reported in the literature.

Recovery of an evolving magnetic flux rope in the solar wind: Decomposing spatial and temporal variations from single-spacecraft data

NASA Astrophysics Data System (ADS)

Hasegawa, H.; Sonnerup, B.; Hu, Q.; Nakamura, T.

2013-12-01

We present a novel single-spacecraft data analysis method for decomposing spatial and temporal variations of physical quantities at points along the path of a spacecraft in spacetime. The method is designed for use in the reconstruction of slowly evolving two-dimensional, magneto-hydrostatic structures (Grad-Shafranov equilibria) in a space plasma. It is an extension of the one developed by Sonnerup and Hasegawa [2010] and Hasegawa et al. [2010], in which it was assumed that variations in the time series of data, recorded as the structures move past the spacecraft, are all due to spatial effects. In reality, some of the observed variations are usually caused by temporal evolution of the structure during the time it moves past the observing spacecraft; the information in the data about the spatial structure is aliased by temporal effects. The purpose here is to remove this time aliasing from the reconstructed maps of field and plasma properties. Benchmark tests are performed by use of synthetic data taken by a virtual spacecraft as it traverses, at a constant velocity, a slowly growing magnetic flux rope in a two-dimensional magnetohydrodynamic simulation of magnetic reconnection. These tests show that the new method can better recover the spacetime behavior of the flux rope than does the original version, in which time aliasing effects had not been removed. An application of the new method to a solar wind flux rope, observed by the ACE spacecraft, suggests that it was evolving in a significant way during the ~17 hour interval of the traversal. References Hasegawa, H., B. U. Ö. Sonnerup, and T. K. M. Nakamura (2010), Recovery of time evolution of Grad-Shafranov equilibria from single-spacecraft data: Benchmarking and application to a flux transfer event, J. Geophys. Res., 115, A11219, doi:10.1029/2010JA015679. Sonnerup, B. U. Ö., and H. Hasegawa (2010), On slowly evolving Grad-Shafranov equilibria, J. Geophys. Res., 115, A11218, doi:10.1029/2010JA015678. Magnetic field maps recovered from (a) the aliased (original) and (b) de-aliased (new) versions of the time evolution method. Colors show the out-of-plane (z) magnetic field component, and white arrows at points along y = 0 show the transverse velocities obtained from the reconstruction. The blue diamonds in panels (b) mark the location of the ACE spacecraft.

Identification of Quantitative Trait Loci That Determine Plasma Total-Cholesterol and Triglyceride Concentrations in DDD/Sgn and C57BL/6J Inbred Mice.

PubMed

Suto, Jun-Ichi; Kojima, Misaki

2017-01-01

DDD/Sgn mice have significantly higher plasma lipid concentrations than C57BL/6J mice. In the present study, we performed quantitative trait loci (QTL) mapping for plasma total-cholesterol (CHO) and triglyceride (TG) concentrations in reciprocal F 2 male intercross populations between the two strains. By single-QTL scans, we identified four significant QTL on chromosomes (Chrs) 1, 5, 17, and 19 for CHO and two significant QTL on Chrs 1 and 12 for TG. By including cross direction as an interactive covariate, we identified separate significant QTL on Chr 17 for CHO but none for TG. When the large phenotypic effect of QTL on Chr 1 was controlled by composite interval mapping, we identified three additional significant QTL on Chrs 3, 4, and 9 for CHO but none for TG. QTL on Chr 19 was a novel QTL for CHO and the allelic effect of this QTL significantly differed between males and females. Whole-exome sequence analysis in DDD/Sgn mice suggested that Apoa2 and Acads were the plausible candidate genes underlying CHO QTL on Chrs 1 and 5, respectively. Thus, we identified a multifactorial basis for plasma lipid concentrations in male mice. These findings will provide insight into the genetic mechanisms of plasma lipid metabolism.

Identification of Quantitative Trait Loci That Determine Plasma Total-Cholesterol and Triglyceride Concentrations in DDD/Sgn and C57BL/6J Inbred Mice

PubMed Central

Kojima, Misaki

2017-01-01

DDD/Sgn mice have significantly higher plasma lipid concentrations than C57BL/6J mice. In the present study, we performed quantitative trait loci (QTL) mapping for plasma total-cholesterol (CHO) and triglyceride (TG) concentrations in reciprocal F2 male intercross populations between the two strains. By single-QTL scans, we identified four significant QTL on chromosomes (Chrs) 1, 5, 17, and 19 for CHO and two significant QTL on Chrs 1 and 12 for TG. By including cross direction as an interactive covariate, we identified separate significant QTL on Chr 17 for CHO but none for TG. When the large phenotypic effect of QTL on Chr 1 was controlled by composite interval mapping, we identified three additional significant QTL on Chrs 3, 4, and 9 for CHO but none for TG. QTL on Chr 19 was a novel QTL for CHO and the allelic effect of this QTL significantly differed between males and females. Whole-exome sequence analysis in DDD/Sgn mice suggested that Apoa2 and Acads were the plausible candidate genes underlying CHO QTL on Chrs 1 and 5, respectively. Thus, we identified a multifactorial basis for plasma lipid concentrations in male mice. These findings will provide insight into the genetic mechanisms of plasma lipid metabolism. PMID:28642824

Method for fabricating beryllium structures

DOEpatents

Hovis, Jr., Victor M.; Northcutt, Jr., Walter G.

1977-01-01

Thin-walled beryllium structures are prepared by plasma spraying a mixture of beryllium powder and about 2500 to 4000 ppm silicon powder onto a suitable substrate, removing the plasma-sprayed body from the substrate and placing it in a sizing die having a coefficient of thermal expansion similar to that of the beryllium, exposing the plasma-sprayed body to a moist atmosphere, outgassing the plasma-sprayed body, and then sintering the plasma-sprayed body in an inert atmosphere to form a dense, low-porosity beryllium structure of the desired thin-wall configuration. The addition of the silicon and the exposure of the plasma-sprayed body to the moist atmosphere greatly facilitate the preparation of the beryllium structure while minimizing the heretofore deleterious problems due to grain growth and grain orientation.

Native protein mapping and visualization of protein interactions in the area of human plasma high-density lipoprotein by combining nondenaturing micro 2DE and quantitative LC-MS/MS.

PubMed

Jin, Ya; Bu, Shujie; Zhang, Jun; Yuan, Qi; Manabe, Takashi; Tan, Wen

2014-07-01

A human plasma sample was subjected to nondenaturing micro 2DE and a gel area (5 mm × 18 mm) that includes high-density lipoprotein (HDL) was cut into 1 mm × 1 mm squares, then the proteins in the 90 gel pieces were analyzed by quantitative LC-MS/MS. Grid-cutting of the gel was employed to; (i) ensure the total analysis of the proteins in the area, (ii) standardize the conditions of analysis by LC-MS/MS, (iii) reconstruct the protein distribution patterns from the quantity data. Totally 154 proteins were assigned in the 90 gel pieces and the quantity distribution of each was reconstructed as a color density pattern (a native protein map). The map of apolipoprotein (Apo) A-I showed a wide apparent mass distribution characteristic to HDL and was compared with the maps of the other 153 proteins. Eleven proteins showed maps of wide distribution that overlapped with the map of Apo A-I, and all have been reported to be the components of HDL. Further, seven minor proteins associated with HDL were detected at the gel positions of high Apo A-I quantity. These results for the first time visualized the localization of HDL apolipoproteins on a nondenaturing 2DE gel and strongly suggested their interactions. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Mapping the Solar Wind from its Source Region into the Outer Corona

NASA Technical Reports Server (NTRS)

Esser, Ruth

1997-01-01

Knowledge of the radial variation of the plasma conditions in the coronal source region of the solar wind is essential to exploring coronal heating and solar wind acceleration mechanisms. The goal of the proposal was to determine as many plasma parameters in the solar wind acceleration region and beyond as possible by coordinating different observational techniques, such as Interplanetary Scintillation Observations, spectral line intensity observations, polarization brightness measurements and X-ray observations. The inferred plasma parameters were then used to constrain solar wind models.

The Plasma Environment at Mercury

NASA Technical Reports Server (NTRS)

Raines, James M.; Gershman, Daniel J.; Zurbuchen, Thomas H.; Gloeckler, George; Slavin, James A.; Anderson, Brian J.; Korth, Haje; Krimigis, Stamatios M.; Killen, Rosemary M.; Sarantos, Menalos;

Shell stability and conditions analyzed using a new method of extracting shell areal density maps from spectrally resolved images of direct-drive inertial confinement fusion implosions

DOE PAGES

Johns, H. M.; Mancini, R. C.; Nagayama, T.; ...

2016-01-25

In warm target direct-drive inertial confinement fusion implosion experiments performed at the OMEGA laser facility, plastic micro-balloons doped with a titanium tracer layer in the shell and filled with deuterium gas were imploded using a low-adiabat shaped laser pulse. Continuum radiation emitted in the core is transmitted through the tracer layer and the resulting spectrum recorded with a gated multi-monochromatic x-ray imager (MMI). Titanium K-shell line absorption spectra observed in the data are due to transitions in L-shell titanium ions driven by the backlighting continuum. The MMI data consist of an array of spectrally resolved images of the implosion. Thesemore » 2-D space-resolved titanium spectral features constrain the plasma conditions and areal density of the titanium doped region of the shell. The MMI data were processed to obtain narrow-band images and space resolved spectra of titanium spectral features. Shell areal density maps, ρL(x,y), extracted using a new method using both narrow-band images and space resolved spectra are confirmed to be consistent within uncertainties. We report plasma conditions in the titanium-doped region of electron temperature (Te) = 400 ± 28 eV, electron number density (N e) = 8.5 × 10 24 ± 2.5 × 10 24 cm –3, and average areal density = 86 ± 7 mg/cm 2. Fourier analysis of areal density maps reveals shell modulations caused by hydrodynamic instability growth near the fuel-shell interface in the deceleration phase. We observe significant structure in modes l = 2–9, dominated by l = 2. We extract a target breakup fraction of 7.1 ± 1.5% from our Fourier analysis. Furthermore, a new method for estimating mix width is evaluated against existing literature and our target breakup fraction. We estimate a mix width of 10.5 ±1 μm.« less

Existence of steady gap solutions in rotating black hole magnetospheres

NASA Astrophysics Data System (ADS)

Levinson, Amir; Segev, Noam

2017-12-01

Under conditions prevailing in certain classes of compact astrophysical systems, the active magnetosphere of a rotating black hole becomes charge starved, giving rise to the formation of a spark gap in which plasma is continuously produced. The plasma production process is accompanied by curvature and inverse Compton emission of gamma rays in the GeV-TeV band, which may be detectable by current and future experiments. The properties of the gap emission have been studied recently using a fully general-relativistic model of a local steady gap. However, this model requires artificial adjustment of the electric current which is determined, in reality, by the global properties of the magnetosphere. In this paper we map the parameter regime in which steady gap solutions exist, using a steady-state gap model in Kerr geometry, and show that such solutions are allowed only under restrictive conditions that may not apply to most astrophysical systems. We further argue that even the allowed solutions are inconsistent with the global magnetospheric structure. We conclude that magnetospheric gaps are inherently intermittent, and point out that this may drastically change their emission properties.

Assessment of Proton Deflectometry for Exploding Wire Experiments

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

Beg, Farhat Nadeem

2013-09-25

This project provides the first demonstration of the application of proton deflectometry for the diagnosis of electromagnetic field topology and current-carrying regions in Z-pinch plasma experiments. Over the course of this project several milestones were achieved. High-energy proton beam generation was demonstrated on the short-pulse high-intensity Leopard laser, (10 Joules in ~350 femtoseconds, and the proton beam generation was shown to be reproducible. Next, protons were used to probe the electromagnetic field structure of short circuit loads in order to benchmark the two numerical codes, the resistive-magnetohydrodynamics (MHD) code, Gorgon, and the hybrid particle-in-cell code, LSP for the interpretation ofmore » results. Lastly, the proton deflectometry technique was used to map the magnetic field structure of pulsed-power-driven plasma loads including wires and supersonic jets formed with metallic foils. Good agreement between the modeling and experiments has been obtained. The demonstrated technique holds great promise to significantly improve the understanding of current flow and electromagnetic field topology in pulsed power driven high energy density plasmas. Proton probing with a high intensity laser was for the first time implemented in the presence of the harsh debris and x-ray producing z-pinch environment driven by a mega-ampere-scale pulsed-power machine. The intellectual merit of the program was that it investigated strongly driven MHD systems and the influence of magnetic field topology on plasma evolution in pulsed power driven plasmas. The experimental program involved intense field-matter interaction in the generation of the proton probe, as well as the generation of plasma subjected to 1 MegaGauss scale magnetic fields. The computational aspect included two well-documented codes, in combination for the first time to provide accurate interpretation of the experimental results. The broader impact included the support of 2 graduate students, one at UCSD and one at NTF, who were exposed to both the experimental physics work, the MHD and PIC modeling of the system. A first generation college undergraduate student was employed to assist in experiments and data analysis throughout the project. Data resulting from the research program were broadly disseminated by publication in scientific journals, and presentation at international and national conferences and workshops.« less

Detection of QTL controlling metabolism, meat quality, and liver quality traits of the overfed interspecific hybrid mule duck.

PubMed

Kileh-Wais, M; Elsen, J M; Vignal, A; Feves, K; Vignoles, F; Fernandez, X; Manse, H; Davail, S; André, J M; Bastianelli, D; Bonnal, L; Filangi, O; Baéza, E; Guéméné, D; Genêt, C; Bernadet, M D; Dubos, F; Marie-Etancelin, C

2013-02-01

The mule duck, an interspecific hybrid obtained by crossing common duck (Anas platyrhynchos) females with Muscovy (Cairina moschata) drakes, is widely used for fatty liver production. The purpose of the present study was to detect and map single and pleiotropic QTL that segregate in the common duck species, and influence the expression of traits in their overfed mule duck offspring. To this end, we generated a common duck backcross (BC) population by crossing Kaiya and heavy Pekin experimental lines, which differ notably in regard to the BW and overfeeding ability of their mule progeny. The BC females were mated to Muscovy drakes and, on average, 4 male mule ducks hatched per BC female (1600 in total) and were measured for growth, metabolism during growth and the overfeeding period, overfeeding ability, and the quality of their breast meat and fatty liver. The phenotypic value of BC females was estimated for each trait by assigning to each female the mean value of the phenotypes of her offspring. Estimations allowed for variance, which depended on the number of male offspring per BC and the heritability of the trait considered. The genetic map used for QTL detection consisted of 91 microsatellite markers aggregated into 16 linkage groups (LG) covering a total of 778 cM. Twenty-two QTL were found to be significant at the 1% chromosome-wide threshold level using the single-trait detection option of the QTLMap software. Most of the QTL detected were related to the quality of breast meat and fatty liver: QTL for meat pH 20 min post mortem were mapped to LG4 (at the 1% genome-wide significance level), and QTL for meat lipid content and cooking losses were mapped to LG2a. The QTL related to fatty liver weight and liver protein and lipid content were for the most part detected on LG2c and LG9. Multitrait analysis highlighted the pleiotropic effects of QTL in these chromosome regions. Apart from the strong QTL for plasma triglyceride content at the end of the overfeeding period mapped to chromosome Z using single-trait analysis, all metabolic trait QTL were detected with the multitrait approach: the QTL mapped to LG14 and LG21 affected the plasma cholesterol and triglyceride contents, whereas the QTL mapped to LG2a seemed to impact glycemia and the basal plasma corticosterone content. A greater density genetic map will be needed to further fine map the QTL.

Normalization of Patient-Identified Plasma Biomarkers in SMNΔ7 Mice following Postnatal SMN Restoration

PubMed Central

Arnold, W. David; Duque, Sandra; Iyer, Chitra C.; Zaworski, Phillip; McGovern, Vicki L.; Taylor, Shannon J.; von Herrmann, Katharine M.; Kobayashi, Dione T.; Chen, Karen S.; Kolb, Stephen J.; Paushkin, Sergey V.; Burghes, Arthur H. M.

2016-01-01

Introduction and Objective Spinal muscular atrophy (SMA) is an autosomal recessive motor neuron disorder. SMA is caused by homozygous loss of the SMN1 gene and retention of the SMN2 gene resulting in reduced levels of full length SMN protein that are insufficient for motor neuron function. Various treatments that restore levels of SMN are currently in clinical trials and biomarkers are needed to determine the response to treatment. Here, we sought to investigate in SMA mice a set of plasma analytes, previously identified in patients with SMA to correlate with motor function. The goal was to determine whether levels of plasma markers were altered in the SMNΔ7 mouse model of SMA and whether postnatal SMN restoration resulted in normalization of the biomarkers. Methods SMNΔ7 and control mice were treated with antisense oligonucleotides (ASO) targeting ISS-N1 to increase SMN protein from SMN2 or scramble ASO (sham treatment) via intracerebroventricular injection on postnatal day 1 (P1). Brain, spinal cord, quadriceps muscle, and liver were analyzed for SMN protein levels at P12 and P90. Ten plasma biomarkers (a subset of biomarkers in the SMA-MAP panel available for analysis in mice) were analyzed in plasma obtained at P12, P30, and P90. Results Of the eight plasma biomarkers assessed, 5 were significantly changed in sham treated SMNΔ7 mice compared to control mice and were normalized in SMNΔ7 mice treated with ASO. Conclusion This study defines a subset of the SMA-MAP plasma biomarker panel that is abnormal in the most commonly used mouse model of SMA. Furthermore, some of these markers are responsive to postnatal SMN restoration. These findings support continued clinical development of these potential prognostic and pharmacodynamic biomarkers. PMID:27907033

Coherent Structures in Plasmas Relevant to Electric Propulsion

DTIC Science & Technology

2016-06-24

AFRL-AFOSR-VA-TR-2016-0229 Coherent Structures in Plasmas Relevant to Electric Propulsion Mark Cappelli LELAND STANFORD JUNIOR UNIV CA Final Report...TITLE AND SUBTITLE Coherent Structures in Plasmas Relevant to Electric Propulsion 5a. CONTRACT NUMBER N/A 5b. GRANT NUMBER FA9550-14-1-0017 5c...to propulsion devices through experimental, theoretical, and numerical studies. 15. SUBJECT TERMS Plasma instabilities in magnetized discharges

Molecular beam epitaxy of InN nanowires on Si

NASA Astrophysics Data System (ADS)

Golam Sarwar, A. T. M.; Carnevale, Santino D.; Kent, Thomas F.; Laskar, Masihhur R.; May, Brelon J.; Myers, Roberto C.

2015-10-01

We report on a systematic growth study of the nucleation process of InN nanowires on Si(1 1 1) substrates using plasma assisted molecular beam epitaxy (PAMBE). Samples are grown with various substrate temperatures and III/V ratios. Scanning electron microscopy, X-ray diffraction spectroscopy, energy dispersive X-ray spectroscopy, and photoluminescence are carried out to map out the variation in structural and optical properties versus growth conditions. Statistical averages of areal density, height, and radius are mapped as a function of substrate temperature and III/V ratio. Three different morphological phases are identified on the growth surface: InN, α-In and β-In. Based on SEM image analysis of samples grown at different conditions, the formation mechanism of these phases is proposed. Finally, the growth phase diagram of PAMBE grown InN on Si under N-rich condition is presented, and tapered versus non-tapered growth conditions are identified. It is found that high growth temperature and low III/V ratio plays a critical role in the growth of non-tapered InN nanowires.

SPECTRO-POLARIMETRIC IMAGING REVEALS HELICAL MAGNETIC FIELDS IN SOLAR PROMINENCE FEET

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

González, M. J. Martínez; Sainz, R. Manso; Ramos, A. Asensio

2015-03-20

Solar prominences are clouds of cool plasma levitating above the solar surface and insulated from the million-degree corona by magnetic fields. They form in regions of complex magnetic topology, characterized by non-potential fields, which can evolve abruptly, disintegrating the prominence and ejecting magnetized material into the heliosphere. However, their physics is not yet fully understood because mapping such complex magnetic configurations and their evolution is extremely challenging, and must often be guessed by proxy from photometric observations. Using state-of-the-art spectro-polarimetric data, we reconstruct the structure of the magnetic field in a prominence. We find that prominence feet harbor helical magneticmore » fields connecting the prominence to the solar surface below.« less

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

Tumurugoti, P.; Clark, B.M.; Edwards, D.J.

Hollandite-rich multiphase waste form compositions processed by melt-solidification and spark plasma sintering (SPS) were characterized, compared, and validated for nuclear waste incorporation. Phase identification by x-ray diffraction (XRD) and electron back-scattered diffraction (EBSD) confirmed hollandite as the major phase present in these samples along with perovskite, pyrochlore and zirconolite. Distribution of selected elements observed by wavelength dispersive spectroscopy (WDS) maps indicated that Cs formed a secondary phase during SPS processing, which was considered undesirable. On the other hand, Cs partitioned into the hollandite phase in melt-processed samples. Further analysis of hollandite structure in melt-processed composition by selected area electron diffractionmore » (SAED) revealed ordered arrangement of tunnel ions (Ba/Cs) and vacancies, suggesting efficient Cs incorporation into the lattice.« less

Transport properties in nontwist area-preserving maps

DOE PAGES

Szezech Jr., J. D.; Caldas, I. L.; Lopes, S. R.; ...

2009-10-23

Nontwist systems, common in the dynamical descriptions of fluids and plasmas, possess a shearless curve with a concomitant transport barrier that eliminates or reduces chaotic transport, even after its breakdown. In order to investigate the transport properties of nontwist systems, we analyze the barrier escape time and barrier transmissivity for the standard nontwist map, a paradigm of such systems. We interpret the sensitive dependence of these quantities upon map parameters by investigating chaotic orbit stickiness and the associated role played by the dominant crossing of stable and unstable manifolds.

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

Frisz, Jessica F.; Klitzing, Haley A.; Lou, Kaiyan

The plasma membranes of mammalian cells are widely expected to contain domains that are enriched with cholesterol and sphingolipids. In this work, we have used high-resolution secondary ion mass spectrometry to directly map the distributions of isotope-labeled cholesterol and sphingolipids in the plasma membranes of intact fibroblast cells. Although acute cholesterol depletion reduced sphingolipid domain abundance, cholesterol was evenly distributed throughout the plasma membrane and was not enriched within the sphingolipid domains. As a result, we rule out favorable cholesterol-sphingolipid interactions as dictating plasma membrane organization in fibroblast cells. Because the sphingolipid domains are disrupted by drugs that depolymerize themore » cells actin cytoskeleton, cholesterol must instead affect the sphingolipid organization via an indirect mechanism that involves the cytoskeleton.« less

Sphingolipid domains in the plasma membranes of fibroblasts are not enriched with cholesterol

DOE PAGES

Frisz, Jessica F.; Klitzing, Haley A.; Lou, Kaiyan; ...

2013-04-22

The plasma membranes of mammalian cells are widely expected to contain domains that are enriched with cholesterol and sphingolipids. In this work, we have used high-resolution secondary ion mass spectrometry to directly map the distributions of isotope-labeled cholesterol and sphingolipids in the plasma membranes of intact fibroblast cells. Although acute cholesterol depletion reduced sphingolipid domain abundance, cholesterol was evenly distributed throughout the plasma membrane and was not enriched within the sphingolipid domains. As a result, we rule out favorable cholesterol-sphingolipid interactions as dictating plasma membrane organization in fibroblast cells. Because the sphingolipid domains are disrupted by drugs that depolymerize themore » cells actin cytoskeleton, cholesterol must instead affect the sphingolipid organization via an indirect mechanism that involves the cytoskeleton.« less

Effects of exposure to simulated microgravity on neuronal catecholamine release and blood pressure responses to norepinephrine and angiotensin

NASA Technical Reports Server (NTRS)

Convertino, V. A.; Ludwig, D. A.; Gray, B. D.; Vernikos, J.

1998-01-01

We tested the hypothesis that exposure to microgravity reduces the neuronal release of catecholamines and blood pressure responses to norepinephrine and angiotensin. Eight men underwent 30 days of 6 degrees head-down tilt (HDT) bedrest to simulate exposure to microgravity. Plasma norepinephrine and mean arterial blood pressure (MAP) were measured before and after a cold pressor test (CPT) and graded norepinephrine infusion (8, 16 and 32 ng/kg/min) on day 6 of a baseline control period (C6) and on days 14 and 27 of HDT. MAP and plasma angiotensin II (Ang-II) were measured during graded Ang-II infusion (1, 2 and 4 ng/kg/min) on C8 and days 16 and 29 of HDT. Baseline total circulating norepinephrine was reduced from 1017ng during the baseline control period to 610 ng at day 14 and 673ng at day 27 of HDT, confirming a hypoadrenergic state. An elevation of norepinephrine (+178 ng) to the CPT during the baseline control period was eliminated by HDT days 14 and 27. During norepinephrine infusion, similar elevations in plasma norepinephrine (7.7 pg/ml/ng/kg/min) caused similar elevations in MAP (0.12 mmHg/ng/kg/min) across all test days. Ang-II infusion produced higher levels of plasma Ang-II during HDT (47.3 pg/ml) than during baseline control (35.5 pg/ml), while producing similar corresponding elevations in blood pressure. While vascular responsiveness to norepinephrine appears unaffected, impaired neuronal release of norepinephrine and reduced vascular responsiveness to Ang-II might contribute to the lessened capacity to vasoconstrict after spaceflight. The time course of alterations indicates effects that occur within two weeks of exposure.

Dynamic unmagnetized plasma in the diamagnetic cavity around comet 67P/Churyumov-Gerasimenko

NASA Astrophysics Data System (ADS)

Hajra, Rajkumar; Henri, Pierre; Vallières, Xavier; Moré, Jerome; Gilet, Nicolas; Wattieaux, Gaetan; Goetz, Charlotte; Richter, Ingo; Tsurutani, Bruce T.; Gunell, Herbert; Nilsson, Hans; Eriksson, Anders I.; Nemeth, Zoltan; Burch, James L.; Rubin, Martin

2018-04-01

The Rosetta orbiter witnessed several hundred diamagnetic cavity crossings (unmagnetized regions) around comet 67P/Churyumov-Gerasimenko during its two year survey of the comet. The characteristics of the plasma environment inside these diamagnetic regions are studied using in situ measurements by the Rosetta Plasma Consortium instruments. Although the unmagnetized plasma density has been observed to exhibit little dynamics compared to the very dynamical magnetized cometary plasma, we detected several localized dynamic plasma structures inside those diamagnetic regions. These plasma structures are not related to the direct ionization of local cometary neutrals. The structures are found to be steepened, asymmetric plasma enhancements with typical rising-to-descending slope ratio of ˜2.8 (±1.9), skewness ˜0.43 (±0.36), mean duration of ˜2.7 (±0.9) min and relative density variation ΔN/N of ˜0.5 (±0.2), observed close to the electron exobase. Similar steepened plasma density enhancements were detected at the magnetized boundaries of the diamagnetic cavity as well as outside the diamagnetic region. The plausible scalelength and propagation direction of the structures are estimated from simple plasma dynamics considerations. It is suggested that they are large-scale unmagnetized plasma enhancements, transmitted from the very dynamical outer magnetized region to the inner magnetic field-free cavity region.

Formation of current singularity in a topologically constrained plasma

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

Zhou, Yao; Huang, Yi-Min; Qin, Hong

2016-02-01

Recently a variational integrator for ideal magnetohydrodynamics in Lagrangian labeling has been developed. Its built-in frozen-in equation makes it optimal for studying current sheet formation. We use this scheme to study the Hahm-Kulsrud-Taylor problem, which considers the response of a 2D plasma magnetized by a sheared field under sinusoidal boundary forcing. We obtain an equilibrium solution that preserves the magnetic topology of the initial field exactly, with a fluid mapping that is non-differentiable. Unlike previous studies that examine the current density output, we identify a singular current sheet from the fluid mapping. These results are benchmarked with a constrained Grad-Shafranovmore » solver. The same signature of current singularity can be found in other cases with more complex magnetic topologies.« less

Investigation of heavy-metal accumulation in selected plant samples using laser induced breakdown spectroscopy and laser ablation inductively coupled plasma mass spectrometry

NASA Astrophysics Data System (ADS)

Galiová, M.; Kaiser, J.; Novotný, K.; Novotný, J.; Vaculovič, T.; Liška, M.; Malina, R.; Stejskal, K.; Adam, V.; Kizek, R.

2008-12-01

Single-pulse Laser-Induced Breakdown Spectroscopy (LIBS) and Laser-Ablation Inductively Coupled Plasma Mass-Spectrometry (LA-ICP-MS) were applied for mapping the silver and copper distribution in Helianthus Annuus L. samples treated with contaminant in controlled conditions. For Ag and Cu detection the 328.07 nm Ag(I) and 324.75 nm Cu(I) lines were used, respectively. The LIBS experimental conditions (mainly the laser energy and the observation window) were optimized in order to avoid self-absorption effect in the measured spectra. In the LA-ICP-MS analysis the Ag 107 and Cu 63 isotopes were detected. The capability of these two analytical techniques for high-resolution mapping of selected trace chemical elements was demonstrated.

Middle Atmosphere Program. Handbook for MAP, volume 19

NASA Technical Reports Server (NTRS)

Goldberg, R. A. (Editor)

1986-01-01

This MAP handbook is concerned with rocket techniques and instrumentation as they are currently employed in the middle atmosphere. It is composed of nine chapters, written by experts on rocket experiments. The emphasis is on measurement techniques rather than results, although results are incorporated wherever they provide examples which illustrate the measurement features. The chapters first cover techniques relating to measurements of neutral dynamics and chemistry, then measurements of the various intermittent and excessive radiation sources which effect the middle atmospheric environment, and finally measurements of the plasma environment including electric fields. The weighting toward plasma related parameters is not accidental, but reflects both the historical headstart given by early development of radio wave and probe techniques to measure electron density, and by the relatively limited number of techniques available for neutral atmospheric measurements.

Surface modification of argon/oxygen plasma treated vulcanized ethylene propylene diene polymethylene surfaces for improved adhesion with natural rubber

NASA Astrophysics Data System (ADS)

Basak, Ganesh C.; Bandyopadhyay, Abhijit; Neogi, Sudarsan; Bhowmick, Anil K.

2011-01-01

Vulcanized ethylene propylene diene polymethylene (EPDM) rubber surface was treated in a radio frequency capacitatively coupled low pressure argon/oxygen plasma to improve adhesion with compounded natural rubber (NR) during co-vulcanization. The plasma modified surfaces were analyzed by means of contact angle measurement, surface energy, attenuated total reflection-infrared spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, energy dispersive X-ray sulfur mapping and atomic force microscopy. Several experimental variables such as plasma power, length of exposure time and composition of the argon-oxygen gas mixture were considered. It was delineated that plasma treatment changed both surface composition and roughness, and consequently increased peel strength. The change in surface composition was mainly ascribed to the formation of C-O and -Cdbnd O functional groups on the vulcanized surfaces. A maximum of 98% improvement in peel strength was observed after plasma treatment.

Characterization of the human plasma phosphoproteome using linear ion trap mass spectrometry and multiple search engines.

PubMed

Carrascal, Montserrat; Gay, Marina; Ovelleiro, David; Casas, Vanessa; Gelpí, Emilio; Abian, Joaquin

2010-02-05

Major plasma protein families play different roles in blood physiology and hemostasis and in immunodefense. Other proteins in plasma can be involved in signaling as chemical messengers or constitute biological markers of the status of distant tissues. In this respect, the plasma phosphoproteome holds potentially relevant information on the mechanisms modulating these processes through the regulation of protein activity. In this work we describe for the first time a collection of phosphopeptides identified in human plasma using immunoaffinity separation of the seven major serum protein families from other plasma proteins, SCX fractionation, and TiO(2) purification prior to LC-MS/MS analysis. One-hundred and twenty-seven phosphosites in 138 phosphopeptides mapping 70 phosphoproteins were identified with FDR < 1%. A high-confidence collection of phosphosites was obtained using a combined search with the OMSSA, SEQUEST, and Phenyx search engines.

Characterizing Suspension Plasma Spray Coating Formation Dynamics through Curvature Measurements

NASA Astrophysics Data System (ADS)

Chidambaram Seshadri, Ramachandran; Dwivedi, Gopal; Viswanathan, Vaishak; Sampath, Sanjay

2016-12-01

Suspension plasma spraying (SPS) enables the production of variety of microstructures with unique mechanical and thermal properties. In SPS, a liquid carrier (ethanol/water) is used to transport the sub-micrometric feedstock into the plasma jet. Considering complex deposition dynamics of SPS technique, there is a need to better understand the relationships among spray conditions, ensuing particle behavior, deposition stress evolution and resultant properties. In this study, submicron yttria-stabilized zirconia particles suspended in ethanol were sprayed using a cascaded arc plasma torch. The stresses generated during the deposition of the layers (termed evolving stress) were monitored via the change in curvature of the substrate measured using an in situ measurement apparatus. Depending on the deposition conditions, coating microstructures ranged from feathery porous to dense/cracked deposits. The evolving stresses and modulus were correlated with the observed microstructures and visualized via process maps. Post-deposition bi-layer curvature measurement via low temperature thermal cycling was carried out to quantify the thermo-elastic response of different coatings. Lastly, preliminary data on furnace cycle durability of different coating microstructures were evaluated. This integrated study involving in situ diagnostics and ex situ characterization along with process maps provides a framework to describe coating formation mechanisms, process parametrics and microstructure description.

What We've Learned from IBEX ENA Imaging of the Heliosheath

NASA Astrophysics Data System (ADS)

Zirnstein, E.

2017-12-01

The Interstellar Boundary Explorer (IBEX) is an Earth-orbiting spacecraft equipped with two single-pixel cameras that detect neutral atoms produced by the interaction of the solar wind (SW) with the very local interstellar medium (VLISM), as well as neutral atoms flowing in from the VLISM itself. Since its launch in 2009, IBEX has provided us with over half a solar cycle of measurements of energetic neutral atom (ENA) fluxes produced in the heliosphere. In particular, a large number of these ENAs originate in the inner heliosheath, a region of nearly incompressible SW plasma that is slowed, compressed, and heated at the termination shock. As the heated SW plasma flows through the heliosheath and down the heliotail, charge-exchange with cold neutral atoms from the VLISM generates ENAs that travel on ballistic trajectories. Some of these ENAs travel to Earth and are detected by IBEX. IBEX all-sky observations of these ENAs show a unique energy and spatial dependence, revealing the structural and plasma properties of the heliosheath. One of the prime scientific objectives of the Interstellar Mapping and Acceleration Probe (IMAP) mission is to understand the SW-VLISM interaction, including the properties of the heliosheath and heliotail. This talk will review key IBEX observations of the inner heliosheath environment, the way they have shaped our understanding of the SW-VLISM interaction, and their implications for the upcoming IMAP mission.

Detergent-Induced Stabilization and Improved 3D Map of the Human Heteromeric Amino Acid Transporter 4F2hc-LAT2

PubMed Central

Harder, Daniel; Stauffer, Mirko; Jeckelmann, Jean-Marc; Brühlmann, Béla; Rosell, Albert; Ilgü, Hüseyin; Kovar, Karin; Palacín, Manuel; Fotiadis, Dimitrios

2014-01-01

Human heteromeric amino acid transporters (HATs) are membrane protein complexes that facilitate the transport of specific amino acids across cell membranes. Loss of function or overexpression of these transporters is implicated in several human diseases such as renal aminoacidurias and cancer. HATs are composed of two subunits, a heavy and a light subunit, that are covalently connected by a disulphide bridge. Light subunits catalyse amino acid transport and consist of twelve transmembrane α-helix domains. Heavy subunits are type II membrane N-glycoproteins with a large extracellular domain and are involved in the trafficking of the complex to the plasma membrane. Structural information on HATs is scarce because of the difficulty in heterologous overexpression. Recently, we had a major breakthrough with the overexpression of a recombinant HAT, 4F2hc-LAT2, in the methylotrophic yeast Pichia pastoris. Microgram amounts of purified protein made possible the reconstruction of the first 3D map of a human HAT by negative-stain transmission electron microscopy. Here we report the important stabilization of purified human 4F2hc-LAT2 using a combination of two detergents, i.e., n-dodecyl-β-D-maltopyranoside and lauryl maltose neopentyl glycol, and cholesteryl hemisuccinate. The superior quality and stability of purified 4F2hc-LAT2 allowed the measurement of substrate binding by scintillation proximity assay. In addition, an improved 3D map of this HAT could be obtained. The detergent-induced stabilization of the purified human 4F2hc-LAT2 complex presented here paves the way towards its crystallization and structure determination at high-resolution, and thus the elucidation of the working mechanism of this important protein complex at the molecular level. PMID:25299125

Detergent-induced stabilization and improved 3D map of the human heteromeric amino acid transporter 4F2hc-LAT2.

PubMed

Meury, Marcel; Costa, Meritxell; Harder, Daniel; Stauffer, Mirko; Jeckelmann, Jean-Marc; Brühlmann, Béla; Rosell, Albert; Ilgü, Hüseyin; Kovar, Karin; Palacín, Manuel; Fotiadis, Dimitrios

2014-01-01

Human heteromeric amino acid transporters (HATs) are membrane protein complexes that facilitate the transport of specific amino acids across cell membranes. Loss of function or overexpression of these transporters is implicated in several human diseases such as renal aminoacidurias and cancer. HATs are composed of two subunits, a heavy and a light subunit, that are covalently connected by a disulphide bridge. Light subunits catalyse amino acid transport and consist of twelve transmembrane α-helix domains. Heavy subunits are type II membrane N-glycoproteins with a large extracellular domain and are involved in the trafficking of the complex to the plasma membrane. Structural information on HATs is scarce because of the difficulty in heterologous overexpression. Recently, we had a major breakthrough with the overexpression of a recombinant HAT, 4F2hc-LAT2, in the methylotrophic yeast Pichia pastoris. Microgram amounts of purified protein made possible the reconstruction of the first 3D map of a human HAT by negative-stain transmission electron microscopy. Here we report the important stabilization of purified human 4F2hc-LAT2 using a combination of two detergents, i.e., n-dodecyl-β-D-maltopyranoside and lauryl maltose neopentyl glycol, and cholesteryl hemisuccinate. The superior quality and stability of purified 4F2hc-LAT2 allowed the measurement of substrate binding by scintillation proximity assay. In addition, an improved 3D map of this HAT could be obtained. The detergent-induced stabilization of the purified human 4F2hc-LAT2 complex presented here paves the way towards its crystallization and structure determination at high-resolution, and thus the elucidation of the working mechanism of this important protein complex at the molecular level.

Influence of the initial parameters of the magnetic field and plasma on the spatial structure of the electric current and electron density in current sheets formed in helium

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

Ostrovskaya, G. V., E-mail: galya-ostr@mail.ru; Markov, V. S.; Frank, A. G., E-mail: annfrank@fpl.gpi.ru

The influence of the initial parameters of the magnetic field and plasma on the spatial structure of the electric current and electron density in current sheets 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 current sheets formed at close parameters of the initial plasma and similar configurations of the initial magnetic fields are revealed.

High-power microwave-induced TM{sub 01} plasma ring

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

Schamiloglu, E.; Jordan, R.; Moreland, L.D.

1996-02-01

Open-shutter photography was used to capture the air breakdown pattern induced by a TM{sub 01} mode radiated by a high-power backward wave oscillator. The resultant plasma ring was formed in air adjacent to a conical horn antenna fitted with a membrane to keep the experiment under vacuum. This image was digitized and further processed using Khoros 2.0 software to obtain the dimensions of the plasma ring. This information was used in an air breakdown analysis to estimate the radiated power, and agrees within 10% with the power measured using field mapping with an open-ended WR-90 waveguide.

Monitoring of conditions inside gas aggregation cluster source during production of Ti/TiOx nanoparticles

NASA Astrophysics Data System (ADS)

Kousal, J.; Kolpaková, A.; Shelemin, A.; Kudrna, P.; Tichý, M.; Kylián, O.; Hanuš, J.; Choukourov, A.; Biederman, H.

2017-10-01

Gas aggregation sources are nowadays rather widely used in the research community for producing nanoparticles. However, the direct diagnostics of conditions inside the source are relatively scarce. In this work, we focused on monitoring the plasma parameters and the composition of the gas during the production of the TiOx nanoparticles. We studied the role of oxygen in the aggregation process and the influence of the presence of the particles on the plasma. The construction of the source allowed us to make a 2D map of the plasma parameters inside the source.

NOAA Office of Exploration and Research > About OER > Organization > Map of

Science.gov Websites

About OER Overview Organization Guiding Documents Organizational Structure Map of Staff and Affiliate Overview Website & Social Media News Room OER Symposium Guiding Documents Organizational Structure Map About OER Overview Organization Guiding Documents Organizational Structure Map of Staff and Affiliate

Advances in Heavy Ion Beam Probe Technology and Operation on MST

NASA Astrophysics Data System (ADS)

Demers, D. R.; Connor, K. A.; Schoch, P. M.; Radke, R. J.; Anderson, J. K.; Craig, D.; den Hartog, D. J.

2003-10-01

A technique to map the magnetic field of a plasma via spectral imaging is being developed with the Heavy Ion Beam Probe on the Madison Symmetric Torus. The technique will utilize two-dimensional images of the ion beam in the plasma, acquired by two CCD cameras, to generate a three-dimensional reconstruction of the beam trajectory. This trajectory, and the known beam ion mass, energy and charge-state, will be used to determine the magnetic field of the plasma. A suitable emission line has not yet been observed since radiation from the MST plasma is both broadband and intense. An effort to raise the emission intensity from the ion beam by increasing beam focus and current has been undertaken. Simulations of the accelerator ion optics and beam characteristics led to a technique, confirmed by experiment, that achieves a narrower beam and marked increase in ion current near the plasma surface. The improvements arising from these simulations will be discussed. Realization of the magnetic field mapping technique is contingent upon accurate reconstruction of the beam trajectory from the camera images. Simulations of two camera CCD images, including the interior of MST, its various landmarks and beam trajectories have been developed. These simulations accept user input such as camera locations, resolution via pixellization and noise. The quality of the images simulated with these and other variables will help guide the selection of viewing port pairs, image size and camera specifications. The results of these simulations will be presented.

Multiscale Auroral Emission Statistics as Evidence of Turbulent Reconnection in Earth's Midtail Plasma Sheet

NASA Technical Reports Server (NTRS)

Klimas, Alex; Uritsky, Vadim; Donovan, Eric

2010-01-01

We provide indirect evidence for turbulent reconnection in Earth's midtail plasma sheet by reexamining the statistical properties of bright, nightside auroral emission events as observed by the UVI experiment on the Polar spacecraft and discussed previously by Uritsky et al. The events are divided into two groups: (1) those that map to absolute value of (X(sub GSM)) < 12 R(sub E) in the magnetotail and do not show scale-free statistics and (2) those that map to absolute value of (X(sub GSM)) > 12 R(sub E) and do show scale-free statistics. The absolute value of (X(sub GSM)) dependence is shown to most effectively organize the events into these two groups. Power law exponents obtained for group 2 are shown to validate the conclusions of Uritsky et al. concerning the existence of critical dynamics in the auroral emissions. It is suggested that the auroral dynamics is a reflection of a critical state in the magnetotail that is based on the dynamics of turbulent reconnection in the midtail plasma sheet.

Optical and magneto-optical properties of one-dimensional magnetized coupled resonator plasma photonic crystals

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

Hamidi, S. M.

2012-01-15

In this paper, the optical and magneto-optical properties of one-dimensional magnetized coupled resonator plasma photonic crystals have been investigated. We use transfer matrix method to solve our magnetized coupled resonator plasma photonic crystals consist of dielectric and magnetized plasma layers. The results of the change in the optical and magneto-optical properties of structure as a result of the alteration in the structural properties such as thickness, plasma frequency and collision frequency, plasma filling factor, number of resonators and dielectric constant of dielectric layers and external magnetic field have been reported. The main feature of this structure is a good magneto-opticalmore » rotation that takes place at the defect modes and the edge of photonic band gap of our proposed optical magnetized plasma waveguide. Our outcomes demonstrate the potential applications of the device for tunable and adjustable filters or reflectors and active magneto-optic in microwave devices under structural parameter and external magnetic field.« less

Optimal contact definition for reconstruction of contact maps.

PubMed

Duarte, Jose M; Sathyapriya, Rajagopal; Stehr, Henning; Filippis, Ioannis; Lappe, Michael

2010-05-27

Contact maps have been extensively used as a simplified representation of protein structures. They capture most important features of a protein's fold, being preferred by a number of researchers for the description and study of protein structures. Inspired by the model's simplicity many groups have dedicated a considerable amount of effort towards contact prediction as a proxy for protein structure prediction. However a contact map's biological interest is subject to the availability of reliable methods for the 3-dimensional reconstruction of the structure. We use an implementation of the well-known distance geometry protocol to build realistic protein 3-dimensional models from contact maps, performing an extensive exploration of many of the parameters involved in the reconstruction process. We try to address the questions: a) to what accuracy does a contact map represent its corresponding 3D structure, b) what is the best contact map representation with regard to reconstructability and c) what is the effect of partial or inaccurate contact information on the 3D structure recovery. Our results suggest that contact maps derived from the application of a distance cutoff of 9 to 11A around the Cbeta atoms constitute the most accurate representation of the 3D structure. The reconstruction process does not provide a single solution to the problem but rather an ensemble of conformations that are within 2A RMSD of the crystal structure and with lower values for the pairwise average ensemble RMSD. Interestingly it is still possible to recover a structure with partial contact information, although wrong contacts can lead to dramatic loss in reconstruction fidelity. Thus contact maps represent a valid approximation to the structures with an accuracy comparable to that of experimental methods. The optimal contact definitions constitute key guidelines for methods based on contact maps such as structure prediction through contacts and structural alignments based on maximum contact map overlap.

Optimal contact definition for reconstruction of Contact Maps

PubMed Central

2010-01-01

Background Contact maps have been extensively used as a simplified representation of protein structures. They capture most important features of a protein's fold, being preferred by a number of researchers for the description and study of protein structures. Inspired by the model's simplicity many groups have dedicated a considerable amount of effort towards contact prediction as a proxy for protein structure prediction. However a contact map's biological interest is subject to the availability of reliable methods for the 3-dimensional reconstruction of the structure. Results We use an implementation of the well-known distance geometry protocol to build realistic protein 3-dimensional models from contact maps, performing an extensive exploration of many of the parameters involved in the reconstruction process. We try to address the questions: a) to what accuracy does a contact map represent its corresponding 3D structure, b) what is the best contact map representation with regard to reconstructability and c) what is the effect of partial or inaccurate contact information on the 3D structure recovery. Our results suggest that contact maps derived from the application of a distance cutoff of 9 to 11Å around the Cβ atoms constitute the most accurate representation of the 3D structure. The reconstruction process does not provide a single solution to the problem but rather an ensemble of conformations that are within 2Å RMSD of the crystal structure and with lower values for the pairwise average ensemble RMSD. Interestingly it is still possible to recover a structure with partial contact information, although wrong contacts can lead to dramatic loss in reconstruction fidelity. Conclusions Thus contact maps represent a valid approximation to the structures with an accuracy comparable to that of experimental methods. The optimal contact definitions constitute key guidelines for methods based on contact maps such as structure prediction through contacts and structural alignments based on maximum contact map overlap. PMID:20507547

High Throughput Plasma Water Treatment

NASA Astrophysics Data System (ADS)

Mujovic, Selman; Foster, John

2016-10-01

The troublesome emergence of new classes of micro-pollutants, such as pharmaceuticals and endocrine disruptors, poses challenges for conventional water treatment systems. In an effort to address these contaminants and to support water reuse in drought stricken regions, new technologies must be introduced. The interaction of water with plasma rapidly mineralizes organics by inducing advanced oxidation in addition to other chemical, physical and radiative processes. The primary barrier to the implementation of plasma-based water treatment is process volume scale up. In this work, we investigate a potentially scalable, high throughput plasma water reactor that utilizes a packed bed dielectric barrier-like geometry to maximize the plasma-water interface. Here, the water serves as the dielectric medium. High-speed imaging and emission spectroscopy are used to characterize the reactor discharges. Changes in methylene blue concentration and basic water parameters are mapped as a function of plasma treatment time. Experimental results are compared to electrostatic and plasma chemistry computations, which will provide insight into the reactor's operation so that efficiency can be assessed. Supported by NSF (CBET 1336375).

Electron Temperature and Plasma Flow Measurements of NIF Hohlraum Plasmas

NASA Astrophysics Data System (ADS)

Barrios, M. A.; Liedahl, D. A.; Schneider, M. B.; Jones, O.; Brow, G. V.; Regan, S. P.; Fournier, K. B.; Moore, A. S.; Ross, J. S.; Eder, D.; Landen, O.; Kauffman, R. L.; Nikroo, A.; Kroll, J.; Jaquez, J.; Huang, H.; Hansen, S. B.; Callahan, D. A.; Hinkel, D. E.; Bradley, D.; Moody, J. D.; LLNL Collaboration; LLE Collaboration; GA Collaboration; SNL Collaboration

2016-10-01

Characterizing the plasma conditions inside NIF hohlraums, in particular mapping the plasma Te, is critical to gaining insight into mechanisms that affect energy coupling and transport in the hohlraum. The dot spectroscopy platform provides a temporal history of the localized Te and plasma flow inside a NIF hohlraum, by introducing a Mn-Co tracer dot, at strategic locations inside the hohlraum, that comes to equilibrium with the local plasma. K-shell X-ray spectroscopy of the tracer dot is recorded onto an absolutely calibrated X-ray streak spectrometer. Isoelectronic and interstage line ratios are used to infer localized Te through comparison with atomic physics calculations using SCRAM. Time resolved X-ray images are simultaneously taken of the expanding dot, providing plasma (ion) flow information. We present recent results provided by this platform and compare with simulations using HYDRA. This work was performed under the auspices of the U.S. Department of Energy by LLNL under Contract DE-AC52-07NA27344.

Resonant- and avalanche-ionization amplification of laser-induced plasma in air

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

Wu, Yue; Zhang, Zhili, E-mail: zzhang24@utk.edu; Jiang, Naibo

2014-10-14

Amplification of laser-induced plasma in air is demonstrated utilizing resonant laser ionization and avalanche ionization. Molecular oxygen in air is ionized by a low-energy laser pulse employing (2 + 1) resonance-enhanced multi-photon ionization (REMPI) to generate seed electrons. Subsequent avalanche ionization of molecular oxygen and nitrogen significantly amplifies the laser-induced plasma. In this plasma-amplification effect, three-body attachments to molecular oxygen dominate the electron-generation and -loss processes, while either nitrogen or argon acts as the third body with low electron affinity. Contour maps of the electron density within the plasma obtained in O₂/N₂ and O₂/Ar gas mixtures are provided to showmore » relative degrees of plasma amplification with respect to gas pressure and to verify that the seed electrons generated by O₂ 2 + 1 REMPI are selectively amplified by avalanche ionization of molecular nitrogen in a relatively low-pressure condition (≤100 Torr). Such plasma amplification occurring in air could be useful in aerospace applications at high altitude.« less

The properties of fast and slow oblique solitons in a magnetized plasma

NASA Astrophysics Data System (ADS)

McKenzie, J. F.; Doyle, T. B.

2002-01-01

This work builds on a recent treatment by McKenzie and Doyle [Phys. Plasmas 8, 4367 (2001)], on oblique solitons in a cold magnetized plasma, to include the effects of plasma thermal pressure. Conservation of total momentum in the direction of wave propagation immediately shows that if the flow is supersonic, compressive (rarefactive) changes in the magnetic pressure induce decelerations (accelerations) in the flow speed, whereas if the flow is subsonic, compressive (rarefactive) changes in the magnetic pressure induce accelerations (decelerations) in the flow speed. Such behavior is characteristic of a Bernoulli-type plasma momentum flux which exhibits a minimum at the plasma sonic point. The plasma energy flux (kinetic plus enthalpy) also shows similar Bernoulli-type behavior. This transonic effect is manifest in the spatial structure equation for the flow speed (in the direction of propagation) which shows that soliton structures may exist if the wave speed lies either (i) in the range between the fast and Alfven speeds or (ii) between the sound and slow mode speed. These conditions follow from the requirement that a defined, characteristic "soliton parameter" m exceeds unity. It is in this latter slow soliton regime that the effects of plasma pressure are most keenly felt. The equilibrium points of the structure equation define the center of the wave. The structure of both fast and slow solitons is elucidated through the properties of the energy integral function of the structure equation. In particular, the slow soliton, which owes its existence to plasma pressure, may have either a compressive or rarefactive nature, and exhibits a rich structure, which is revealed through the spatial structure of the longitudinal speed and its corresponding transverse velocity hodograph.

Structure contour map of the greater Green River basin, Wyoming, Colorado, and Utah

USGS Publications Warehouse

Lickus, M.R.; Law, B.E.

1988-01-01

The Greater Green River basin of Wyoming, Colorado, and Utah contains five basins and associated major uplifts (fig. 1). Published structure maps of the region have commonly used the top of the Lower Cretaceous Dakota Sandstone as a structural datum (Petroleum Ownership Map Company (POMCO), 1984; Rocky Mountain Association of Geologists, 1972). However, because relatively few wells in this area penetrate the Dakota, the Dakota structural datum has to be constructed by projecting down from shallower wells. Extrapolating in this manner may produce errors in the map. The primary purpose of this report is to present a more reliable structure contour map of the Greater Green River basin based on datums that are penetrated by many wells. The final map shows the large- to small-scale structures present in the Greater Green River basin. The availability of subsurface control and the map scale determined whether or not a structural feature was included on the map. In general, large structures such as the Moxa arch, Pinedale anticline, and other large folds were placed on the map based solely on the structure contours. In comparison, smaller folds and some faults were placed on the map based on structure contours and other reports (Bader 1987; Bradley 1961; Love and Christiansen, 1985; McDonald, 1975; Roehler, 1979; Wyoming Geological Association Oil and Gas Symposium Committee, 1979). State geologic maps and other reports were used to position basin margin faults (Bryant, 1985; Gries, 1983a, b; Hansen 1986; Hintze, 1980; Love and Christiansen, 1985; Tweto, 1979, 1983). In addition, an interpreted east-west-trending regional seismic line by Garing and Tainter (1985), which shows the basin configuration in cross-section, was helpful in locating buried faults, such as the high-angle reverse or thrust fault along the west flank of the Rock Springs uplift.

Particle trapping: A key requisite of structure formation and stability of Vlasov–Poisson plasmas

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

Schamel, Hans, E-mail: hans.schamel@uni-bayreuth.de

2015-04-15

Particle trapping is shown to control the existence of undamped coherent structures in Vlasov–Poisson plasmas and thereby affects the onset of plasma instability beyond the realm of linear Landau theory.

Magnetosheath jets: MMS observations of internal structures and jet interactions with ambient plasma

NASA Astrophysics Data System (ADS)

Plaschke, F.; Karlsson, T.; Hietala, H.; Archer, M. O.; Voros, Z.; Nakamura, R.; Magnes, W.; Baumjohann, W.; Torbert, R. B.; Russell, C. T.; Giles, B. L.

2017-12-01

The dayside magnetosheath downstream of the quasi-parallel bow shock is commonly permeated by high-speed jets. Under low IMF cone angle conditions, large scale jets alone (with cross-sectional diameters of over 2 Earth radii) have been found to impact the subsolar magnetopause once every 6 minutes - smaller scale jets occurring much more frequently. The consequences of jet impacts on the magnetopause can be significant: they may trigger local reconnection and waves, alter radiation belt electron drift paths, disturb the geomagnetic field, and potentially generate diffuse throat aurora at the dayside ionosphere. Although some basic statistical properties of jets are well-established, their internal structure and interactions with the surrounding magnetosheath plasma are rather unknown. We present Magnetospheric Multiscale (MMS) observations which reveal a rich jet-internal structure of high-amplitude plasma moment and magnetic field variations and associated currents. These variations/structures are generally found to be in thermal and magnetic pressure balance; they mostly (but not always) convect with the plasma flow. Small velocity differences between plasma and structures are revealed via four-spacecraft timing analysis. Inside a jet core region, where the plasma velocity maximizes, structures are found to propagate forward (i.e., with the jet), whereas backward propagation is found outside that core region. Although super-magnetosonic flows are detected by MMS in the spacecraft frame of reference, no fast shock is seen as the jet plasma is sub-magnetosonic with respect to the ambient magnetosheath plasma. Instead, the fast jet plasma pushes ambient magnetosheath plasma ahead of the jet out of the way, possibly generating anomalous sunward flows in the vicinity, and modifies the magnetic field aligning it with the direction of jet propagation.

Coming To Know: The Role of the Concept Map--Mirror, Assistant, Master?

ERIC Educational Resources Information Center

McAleese, Ray

This paper explains the process of creating and managing concept maps, using reflection as a focus for its argument. Section 1, What is a Concept Map?, highlights the background and definition of concept mapping, explains how maps signify virtual conceptual structures, looks at structural knowledge, provides an example of a concept map, and…

Concept Map Structure, Gender and Teaching Methods: An Investigation of Students' Science Learning

ERIC Educational Resources Information Center

Gerstner, Sabine; Bogner, Franz X.

2009-01-01

Background: This study deals with the application of concept mapping to the teaching and learning of a science topic with secondary school students in Germany. Purpose: The main research questions were: (1) Do different teaching approaches affect concept map structure or students' learning success? (2) Is the structure of concept maps influenced…

Iconicity as structure mapping

PubMed Central

Emmorey, Karen

2014-01-01

Linguistic and psycholinguistic evidence is presented to support the use of structure-mapping theory as a framework for understanding effects of iconicity on sign language grammar and processing. The existence of structured mappings between phonological form and semantic mental representations has been shown to explain the nature of metaphor and pronominal anaphora in sign languages. With respect to processing, it is argued that psycholinguistic effects of iconicity may only be observed when the task specifically taps into such structured mappings. In addition, language acquisition effects may only be observed when the relevant cognitive abilities are in place (e.g. the ability to make structural comparisons) and when the relevant conceptual knowledge has been acquired (i.e. information key to processing the iconic mapping). Finally, it is suggested that iconicity is better understood as a structured mapping between two mental representations than as a link between linguistic form and human experience. PMID:25092669

A Preliminary Investigation of Hall Thruster Technology

NASA Technical Reports Server (NTRS)

Gallimore, Alec D.

1997-01-01

A three-year, NASA/BMDO-sponsored experimental program to conduct performance and plume plasma property measurements on two Russian Stationary Plasma Thrusters (SPTs) has been completed. The program utilized experimental facilitates at the University of Michigan's Plasmadynamics and Electric Propulsion Laboratory (PEPL). The main features of the proposed effort were as follows: We Characterized Hall thruster [and arcjet] performance by measuring ion exhaust velocity with probes at various thruster conditions. Used a variety of probe diagnostics in the thruster plume to measure plasma properties and flow properties including T(sub e) and n(sub e), ion current density and ion energy distribution, and electric fields by mapping plasma potential. Used emission spectroscopy to identify species within the plume and to measure electron temperatures.

Optical and structural properties of plasma-treated Cordyceps bassiana spores as studied by circular dichroism, absorption, and fluorescence spectroscopy

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

Lee, Geon Joon, E-mail: gjlee@kw.ac.kr; Sim, Geon Bo; Choi, Eun Ha

To understand the killing mechanism of fungal spores by plasma treatment, the optical, structural, and biological properties of the insect pathogenic fungus Cordyceps bassiana spores were studied. A nonthermal atmospheric-pressure plasma jet (APPJ) was used to treat the spores in aqueous solution. Optical emission spectra of the APPJ acquired in air indicated emission peaks corresponding to hydroxyl radicals and atomic oxygen. When the APPJ entered the aqueous solution, additional reactive species were derived from the interaction of plasma radicals with the aqueous solution. Fluorescence and absorption spectroscopy confirmed the generation of hydroxyl radicals and hydrogen peroxide in the plasma-activated watermore » (PAW). Spore counting showed that plasma treatment significantly reduced spore viability. Absorption spectroscopy, circular dichroism (CD) spectroscopy, and agarose gel electrophoresis of the DNA extracted from plasma-treated spores showed a reduction in spore DNA content. The magnitude of the dip in the CD spectrum was lower in the plasma-treated spores than in the control, indicating that plasma treatment causes structural modifications and/or damage to cellular components. Tryptophan fluorescence intensity was lower in the plasma-treated spores than in the control, suggesting that plasma treatment modified cell wall proteins. Changes in spore viability and DNA content were attributed to structural modification of the cell wall by reactive species coming from the APPJ and the PAW. Our results provided evidence that the plasma radicals and the derived reactive species play critical roles in fungal spore inactivation.« less

Optical and structural properties of plasma-treated Cordyceps bassiana spores as studied by circular dichroism, absorption, and fluorescence spectroscopy

NASA Astrophysics Data System (ADS)

Lee, Geon Joon; Sim, Geon Bo; Choi, Eun Ha; Kwon, Young-Wan; Kim, Jun Young; Jang, Siun; Kim, Seong Hwan

2015-01-01

To understand the killing mechanism of fungal spores by plasma treatment, the optical, structural, and biological properties of the insect pathogenic fungus Cordyceps bassiana spores were studied. A nonthermal atmospheric-pressure plasma jet (APPJ) was used to treat the spores in aqueous solution. Optical emission spectra of the APPJ acquired in air indicated emission peaks corresponding to hydroxyl radicals and atomic oxygen. When the APPJ entered the aqueous solution, additional reactive species were derived from the interaction of plasma radicals with the aqueous solution. Fluorescence and absorption spectroscopy confirmed the generation of hydroxyl radicals and hydrogen peroxide in the plasma-activated water (PAW). Spore counting showed that plasma treatment significantly reduced spore viability. Absorption spectroscopy, circular dichroism (CD) spectroscopy, and agarose gel electrophoresis of the DNA extracted from plasma-treated spores showed a reduction in spore DNA content. The magnitude of the dip in the CD spectrum was lower in the plasma-treated spores than in the control, indicating that plasma treatment causes structural modifications and/or damage to cellular components. Tryptophan fluorescence intensity was lower in the plasma-treated spores than in the control, suggesting that plasma treatment modified cell wall proteins. Changes in spore viability and DNA content were attributed to structural modification of the cell wall by reactive species coming from the APPJ and the PAW. Our results provided evidence that the plasma radicals and the derived reactive species play critical roles in fungal spore inactivation.

Vacuum arc plasma thrusters with inductive energy storage driver

NASA Technical Reports Server (NTRS)

Schein, Jochen (Inventor); Gerhan, Andrew N. (Inventor); Woo, Robyn L. (Inventor); Au, Michael Y. (Inventor); Krishnan, Mahadevan (Inventor)

2004-01-01

An apparatus for producing a vacuum arc plasma source device using a low mass, compact inductive energy storage circuit powered by a low voltage DC supply acts as a vacuum arc plasma thruster. An inductor is charged through a switch, subsequently the switch is opened and a voltage spike of Ldi/dt is produced initiating plasma across a resistive path separating anode and cathode. The plasma is subsequently maintained by energy stored in the inductor. Plasma is produced from cathode material, which allows for any electrically conductive material to be used. A planar structure, a tubular structure, and a coaxial structure allow for consumption of cathode material feed and thereby long lifetime of the thruster for long durations of time.

Likelihood-based modification of experimental crystal structure electron density maps

DOEpatents

Terwilliger, Thomas C [Sante Fe, NM

2005-04-16

A maximum-likelihood method for improves an electron density map of an experimental crystal structure. A likelihood of a set of structure factors {F.sub.h } is formed for the experimental crystal structure as (1) the likelihood of having obtained an observed set of structure factors {F.sub.h.sup.OBS } if structure factor set {F.sub.h } was correct, and (2) the likelihood that an electron density map resulting from {F.sub.h } is consistent with selected prior knowledge about the experimental crystal structure. The set of structure factors {F.sub.h } is then adjusted to maximize the likelihood of {F.sub.h } for the experimental crystal structure. An improved electron density map is constructed with the maximized structure factors.

Observational evidence of predawn plasma bubble and its irregularity scales in Southeast Asia

NASA Astrophysics Data System (ADS)

Watthanasangmechai, K.; Tsunoda, R. T.; Yokoyama, T.; Ishii, M.; Tsugawa, T.

2016-12-01

This paper describes an event of deep plasma depletion simultaneously detected with GPS, GNU Radio Beacon Receiver (GRBR) and in situ satellite measurement from DMFPF15. The event is on March 7, 2012 at 4:30 LT with geomagnetic quiet condition. Such a sharp depletion at plasma bubble wall detected at predawn is interesting but apparently rare event. Only one event is found from all dataset in March 2012. The inside structure of the predawn plasma bubble was clearly captured by DMSPF15 and the ground-based GRBR. The envelop structure seen from the precessed GPS-TEC appeares as a cluster. The observed cluster is concluded as the structure at the westwall of an upwelling of the large-scale wave structure, that accompanies the fifty- and thousand-km scales. This event is consistent with the plasma bubble structure simulated from the high-resolution bubble (HIRB) model.

Diagnostic study of multiple double layer formation in expanding RF plasma

NASA Astrophysics Data System (ADS)

Chakraborty, Shamik; Paul, Manash Kumar; Roy, Jitendra Nath; Nath, Aparna

2018-03-01

Intensely luminous double layers develop and then expand in size in a visibly glowing RF discharge produced using a plasma source consisting of a semi-transparent cylindrical mesh with a central electrode, in a linear plasma chamber. Although RF discharge is known to be independent of device geometry in the absence of magnetic field, the initiation of RF discharge using such a plasma source results in electron drift and further expansion of the plasma in the vessel. The dynamics of complex plasma structures are studied through electric probe diagnostics in the expanding RF plasma. The measurements made to study the parametric dependence of evolution of double layer structures are analyzed and presented here. The plasma parameter measurements suggest that the complex potential structures initially form with low potential difference between the layers and then gradually expand producing burst oscillations. The present study provides interesting information about the stability of plasma sheath and charge particle dynamics in it that are important to understand the underlying basic sheath physics along with applications in plasma acceleration and propulsion.

Sequence-structure mapping errors in the PDB: OB-fold domains

PubMed Central

Venclovas, Česlovas; Ginalski, Krzysztof; Kang, Chulhee

2004-01-01

The Protein Data Bank (PDB) is the single most important repository of structural data for proteins and other biologically relevant molecules. Therefore, it is critically important to keep the PDB data, as much as possible, error-free. In this study, we have analyzed PDB crystal structures possessing oligonucleotide/oligosaccharide binding (OB)-fold, one of the highly populated folds, for the presence of sequence-structure mapping errors. Using energy-based structure quality assessment coupled with sequence analyses, we have found that there are at least five OB-structures in the PDB that have regions where sequences have been incorrectly mapped onto the structure. We have demonstrated that the combination of these computation techniques is effective not only in detecting sequence-structure mapping errors, but also in providing guidance to correct them. Namely, we have used results of computational analysis to direct a revision of X-ray data for one of the PDB entries containing a fairly inconspicuous sequence-structure mapping error. The revised structure has been deposited with the PDB. We suggest use of computational energy assessment and sequence analysis techniques to facilitate structure determination when homologs having known structure are available to use as a reference. Such computational analysis may be useful in either guiding the sequence-structure assignment process or verifying the sequence mapping within poorly defined regions. PMID:15133161

ARE TORNADO-LIKE MAGNETIC STRUCTURES ABLE TO SUPPORT SOLAR PROMINENCE PLASMA?

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

Luna, M.; Moreno-Insertis, F.; Priest, E.

Recent high-resolution and high-cadence observations have surprisingly suggested that prominence barbs exhibit apparent rotating motions suggestive of a tornado-like structure. Additional evidence has been provided by Doppler measurements. The observations reveal opposite velocities for both hot and cool plasma on the two sides of a prominence barb. This motion is persistent for several hours and has been interpreted in terms of rotational motion of prominence feet. Several authors suggest that such barb motions are rotating helical structures around a vertical axis similar to tornadoes on Earth. One of the difficulties of such a proposal is how to support cool prominencemore » plasma in almost-vertical structures against gravity. In this work we model analytically a tornado-like structure and try to determine possible mechanisms to support the prominence plasma. We have found that the Lorentz force can indeed support the barb plasma provided the magnetic structure is sufficiently twisted and/or significant poloidal flows are present.« less

Plasma turbulence and coherent structures in the polar cap observed by the ICI-2 sounding rocket

NASA Astrophysics Data System (ADS)

Spicher, A.; Miloch, W. J.; Clausen, L. B. N.; Moen, J. I.

2015-12-01

The electron density data from the ICI-2 sounding rocket experiment in the high-latitude F region ionosphere are analyzed using the higher-order spectra and higher-order statistics. Two regions of enhanced fluctuations are chosen for detailed analysis: the trailing edge of a polar cap patch and an electron density enhancement associated with particle precipitation. While these two regions exhibit similar power spectra, our analysis reveals that their internal structures are significantly different. The structures on the edge of the polar cap patch are likely due to nonlinear wave interactions since this region is characterized by intermittency and significant coherent mode coupling. The plasma enhancement subjected to precipitation, however, exhibits stronger random characteristics with uncorrelated phases of density fluctuations. These results suggest that particle precipitation plays a fundamental role in ionospheric plasma structuring creating turbulent-like structures. We discuss the physical mechanisms that cause plasma structuring as well as the possible processes for the low-frequency part of the spectrum in terms of plasma instabilities.

Accaleration of Electrons of the Outer Electron Radiation Belt and Auroral Oval Dynamics

NASA Astrophysics Data System (ADS)

Antonova, Elizaveta; Ovchinnikov, Ilya; Riazantseva, Maria; Znatkova, Svetlana; Pulinets, Maria; Vorobjev, Viachislav; Yagodkina, Oksana; Stepanova, Marina

2016-07-01

We summarize the results of experimental observations demonstrating the role of auroral processes in the formation of the outer electron radiation belt and magnetic field distortion during magnetic storms. We show that the auroral oval does not mapped to the plasma sheet proper (region with magnetic field lines stretched in the tailward direction). It is mapped to the surrounding the Earth plasma ring in which transverse currents are closed inside the magnetosphere. Such currents constitute the high latitude continuation of the ordinary ring current. Mapping of the auroral oval to the region of high latitude continuation of the ordinary ring current explains the ring like shape of the auroral oval with finite thickness near noon and auroral oval dynamics during magnetic storms. The auroral oval shift to low latitudes during storms. The development of the ring current produce great distortion of the Earth's magnetic field and corresponding adiabatic variations of relativistic electron fluxes. Development of the asymmetric ring current produce the dawn-dusk asymmetry of such fluxes. We analyze main features of the observed processes including formation of sharp plasma pressure profiles during storms. The nature of observed pressure peak is analyzed. It is shown that the observed sharp pressure peak is directly connected with the creation of the seed population of relativistic electrons. The possibility to predict the position of new radiation belt during recovery phase of the magnetic storm using data of low orbiting and ground based observations is demonstrated.

Tomographic diagnostics of nonthermal plasmas

NASA Astrophysics Data System (ADS)

Denisova, Natalia

2009-10-01

In the previous work [1], we discussed a ``technology'' of tomographic method and relations between the tomographic diagnostics in thermal (equilibrium) and nonthermal (nonequilibrium) plasma sources. The conclusion has been made that tomographic reconstruction in thermal plasma sources is the standard procedure at present, which can provide much useful information on the plasma structure and its evolution in time, while the tomographic reconstruction of nonthermal plasma has a great potential at making a contribution to understanding the fundamental problem of substance behavior in strongly nonequilibrium conditions. Using medical terminology, one could say, that tomographic diagnostics of the equilibrium plasma sources studies their ``anatomic'' structure, while reconstruction of the nonequilibrium plasma is similar to the ``physiological'' examination: it is directed to study the physical mechanisms and processes. The present work is focused on nonthermal plasma research. The tomographic diagnostics is directed to study spatial structures formed in the gas discharge plasmas under the influence of electrical and gravitational fields. The ways of plasma ``self-organization'' in changing and extreme conditions are analyzed. The analysis has been made using some examples from our practical tomographic diagnostics of nonthermal plasma sources, such as low-pressure capacitive and inductive discharges. [0pt] [1] Denisova N. Plasma diagnostics using computed tomography method // IEEE Trans. Plasma Sci. 2009 37 4 502.

Navigating 3D electron microscopy maps with EM-SURFER.

PubMed

Esquivel-Rodríguez, Juan; Xiong, Yi; Han, Xusi; Guang, Shuomeng; Christoffer, Charles; Kihara, Daisuke

2015-05-30

The Electron Microscopy DataBank (EMDB) is growing rapidly, accumulating biological structural data obtained mainly by electron microscopy and tomography, which are emerging techniques for determining large biomolecular complex and subcellular structures. Together with the Protein Data Bank (PDB), EMDB is becoming a fundamental resource of the tertiary structures of biological macromolecules. To take full advantage of this indispensable resource, the ability to search the database by structural similarity is essential. However, unlike high-resolution structures stored in PDB, methods for comparing low-resolution electron microscopy (EM) density maps in EMDB are not well established. We developed a computational method for efficiently searching low-resolution EM maps. The method uses a compact fingerprint representation of EM maps based on the 3D Zernike descriptor, which is derived from a mathematical series expansion for EM maps that are considered as 3D functions. The method is implemented in a web server named EM-SURFER, which allows users to search against the entire EMDB in real-time. EM-SURFER compares the global shapes of EM maps. Examples of search results from different types of query structures are discussed. We developed EM-SURFER, which retrieves structurally relevant matches for query EM maps from EMDB within seconds. The unique capability of EM-SURFER to detect 3D shape similarity of low-resolution EM maps should prove invaluable in structural biology.

First results from ideal 2-D MHD reconstruction: magnetopause reconnection event seen by Cluster

NASA Astrophysics Data System (ADS)

Teh, W.-L.; Ã-. Sonnerup, B. U.

2008-09-01

We have applied a new reconstruction method (Sonnerup and Teh, 2008), based on the ideal single-fluid MHD equations in a steady-state, two-dimensional geometry, to a reconnection event observed by the Cluster-3 (C3) spacecraft on 5 July 2001, 06:23 UT, at the dawn-side Northern-Hemisphere magnetopause. The event has been previously studied by use of Grad-Shafranov (GS) reconstruction, performed in the deHoffmann-Teller frame, and using the assumption that the flow effects were either negligible or the flow was aligned with the magnetic field. Our new method allows the reconstruction to be performed in the frame of reference moving with the reconnection site (the X-line). In the event studied, this motion is tailward/equatorward at 140 km/s. The principal result of the study is that the new method functions well, generating a magnetic field map that is qualitatively similar to those obtained in the earlier GS-based reconstructions but now includes the reconnection site itself. In comparison with the earlier map by Hasegawa et al. (2004), our new map has a slightly improved ability (cc=0.979 versus cc=0.975) to predict the fields measured by the other three Cluster spacecraft, at distances from C3 ranging from 2132 km (C1) to 2646 km (C4). The new field map indicates the presence of a magnetic X-point, located some 5300 km tailward/equatorward of C3 at the time of its traversal of the magnetopause. In the immediate vicinity of the X-point, the ideal-MHD assumption breaks down, i.e. resistive and/or other effects should be included. We have circumvented this problem by an ad-hoc procedure in which we allow the axial part of convection electric field to be non-constant near the reconnection site. The new reconstruction method also provides a map of the velocity field, in which the inflow into the wedge of reconnected field lines and the plasma jet within it can be seen, and maps of the electric potential and of the electric current distribution. Even though the velocity map is expected to be inaccurate near the X-point, it provides high-quality predictions (cc=0.969) of the velocity components at points along the path of C1, some of which are close to the X-point; the predictions of density and pressure are less good. Except near the reconnection site, the new reconstruction provides a complete characterization, in unprecedented detail, of the entire dynamic plasma and field equilibrium, reconstructed from the C3 data. It represents our best prediction to date of what the actual configuration was like. But, since substantial time variations were present in the event, the recovered structure by necessity includes considerable time aliasing. The invariant direction used in the reconstruction, is found to agree, within 6°, with a recent theoretical prediction of the X-line orientation by Swisdak and Drake (2007).

A Plasma Trajectory Back-Tracing Tool Based on SuperDARN Convection Patterns

NASA Astrophysics Data System (ADS)

David, M.; Sojka, J. J.; Schunk, R. W.; Coster, A. J.; Sterne, K. T.

2017-12-01

Horizontal transport of plasma is one of the dominant factors in determining the distribution of plasma in the F-region ionosphere; this transport is driven by the magnetospheric convection electric field. When studying any electron density feature in the polar cap ionosphere, such as a density patch, TID, or tongue of ionization (TOI), one needs to know where that feature came from; was it generated by local production processes where it lies, or was it transported from another location? The path traveled by a plasma flux tube or plasma packet, which we call a trajectory, is determined by the time-varying convection electric field, and to whatever extent this electric field is known, one can back-trace the history of the plasma density feature in order to answer key questions about it, such as: Was this plasma exposed to sunlight in recent hours? Has this plasma packet passed through the auroral precipitation oval? Did it pass through the cusp? And since movement of a plasma flux tube toward the pole may cause upward ion drifts that result in density increases it is important to know whether the recent history of the density feature includes such convection toward (or away from) the pole.SuperDARN [Super Dual Auroral Radar Network] contains a data base of convection electric field patterns derived from ground station observations and the use of models to fill in gaps in the data. At Utah State University we have developed a software tool based on the SuperDARN convection patterns (which come at a time cadence of 2 minutes) to allow one to back-trace the history of polar cap plasma for an arbitrary length of time.The figure below shows a series of GPS TEC maps of the Northern Hemisphere in magnetic coordinates for 06 March 2016 in which a TOI feature forms at about 1700 UT. A series of locations, marked with X, are chosen such that they lie within the TOI at the time of the last panel (1730 UT); then, the plasma trajectory paths for these 15 locations are traced backward in time for 5 hours, and their locations are plotted on the TEC maps for universal times of 1230, 1330, 1430, 1530, and 1630.

Sterilization mechanism of nitrogen gas plasma: induction of secondary structural change in protein.

PubMed

Sakudo, Akikazu; Higa, Masato; Maeda, Kojiro; Shimizu, Naohiro; Imanishi, Yuichiro; Shintani, Hideharu

2013-07-01

The mechanism of action on biomolecules of N₂ gas plasma, a novel sterilization technique, remains unclear. Here, the effect of N₂ gas plasma on protein structure was investigated. BSA, which was used as the model protein, was exposed to N₂ gas plasma generated by short-time high voltage pulses from a static induction thyristor power supply. N₂ gas plasma-treated BSA at 1.5 kilo pulses per second showed evidence of degradation and modification when assessed by Coomassie brilliant blue staining and ultraviolet spectroscopy at 280 nm. Fourier transform infrared spectroscopy analysis was used to determine the protein's secondary structure. When the amide I region was analyzed in the infrared spectra according to curve fitting and Fourier self-deconvolution, N₂ gas plasma-treated BSA showed increased α-helix and decreased β-turn content. Because heating decreased α-helix and increased β-sheet content, the structural changes induced by N₂ gas plasma-treatment of BSA were not caused by high temperatures. Thus, the present results suggest that conformational changes induced by N₂ gas plasma are mediated by mechanisms distinct from heat denaturation. © 2013 The Societies and Wiley Publishing Asia Pty Ltd.

Plasma impact on structural, morphological and optical properties of copper acetylacetonate thin films

NASA Astrophysics Data System (ADS)

Abdel-Khalek, H.; El-Samahi, M. I.; El-Mahalawy, Ahmed M.

2018-06-01

The influence of plasma exposure on structural, morphological and optical properties of copper (II) acetylacetonate thin films deposited by thermal evaporation technique was investigated. Copper (II) acetylacetonate as-grown thin films were exposed to the atmospheric plasma for different times. The exposure of as-grown cu(acac)2 thin film to atmospheric plasma for 5 min modified its structural, morphological and optical properties. The effect of plasma exposure on structure and roughness of cu(acac)2 thin films was evaluated by XRD and AFM techniques, respectively. The XRD results showed an increment in crystallinity due to exposure for 5 min, but, when the exposure time reaches 10 min, the film was transformed to an amorphous state. The AFM results revealed a strong modification of films roughness when the average roughness decreased from 63.35 nm to 1 nm as a result of interaction with plasma. The optical properties of as-grown and plasma exposured cu(acac)2 thin films were studied using spectrophotometric method. The exposure of cu(acac)2 thin films to plasma produced the indirect energy gap decrease from 3.20 eV to 2.67 eV for 10 min exposure time. The dispersion parameters were evaluated in terms of single oscillator model for as-grown and plasma exposured thin films. The influence of plasma exposure on third order optical susceptibility was studied.

Are supernova remnants quasi-parallel or quasi-perpendicular accelerators

NASA Technical Reports Server (NTRS)

Spangler, S. R.; Leckband, J. A.; Cairns, I. H.

1989-01-01

Observations of shock waves in the solar system which show a pronounced difference in the plasma wave and particle environment depending on whether the shock is propagating along or perpendicular to the interplanetary magnetic field are discussed. Theories for particle acceleration developed for quasi-parallel and quasi-perpendicular shocks, when extended to the interstellar medium suggest that the relativistic electrons in radio supernova remnants are accelerated by either the Q parallel or Q perpendicular mechanisms. A model for the galactic magnetic field and published maps of supernova remnants were used to search for a dependence of structure on the angle Phi. Results show no tendency for the remnants as a whole to favor the relationship expected for either mechanism, although individual sources resemble model remnants of one or the other acceleration process.

Averaged kick maps: less noise, more signal…and probably less bias

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

Pražnikar, Jure; Afonine, Pavel V.; Gunčar, Gregor

2009-09-01

Averaged kick maps are the sum of a series of individual kick maps, where each map is calculated from atomic coordinates modified by random shifts. These maps offer the possibility of an improved and less model-biased map interpretation. Use of reliable density maps is crucial for rapid and successful crystal structure determination. Here, the averaged kick (AK) map approach is investigated, its application is generalized and it is compared with other map-calculation methods. AK maps are the sum of a series of kick maps, where each kick map is calculated from atomic coordinates modified by random shifts. As such, theymore » are a numerical analogue of maximum-likelihood maps. AK maps can be unweighted or maximum-likelihood (σ{sub A}) weighted. Analysis shows that they are comparable and correspond better to the final model than σ{sub A} and simulated-annealing maps. The AK maps were challenged by a difficult structure-validation case, in which they were able to clarify the problematic region in the density without the need for model rebuilding. The conclusion is that AK maps can be useful throughout the entire progress of crystal structure determination, offering the possibility of improved map interpretation.« less

Compositional and structural analysis of nitrogen incorporated and ion implanted diamond thin films

NASA Astrophysics Data System (ADS)

Garratt, Elias James

Significant progress in area of nano-structured thin film systems has taken place in recent decades. In particular, diamond thin film systems are being widely studied for their wear resistant, optical and electronic properties. Of the various methods researchers use to modify the structure of such films, three techniques in particular are of interest due to their versatility: modification of the growth atmosphere, growth on metalized substrates, providing an interfacial layer, and modification through post-growth ion implantation. The aim of this study is to investigate the effects each has to the structure and composition of elements. Different techniques are applied in each section; nitrogen gas dilution in a microwave plasma CVD system, diamond deposition on a metal interfacial layer and ion implantation in thin nanocrystalline diamond film. The forms of nanocrystalline diamond film resulting from such modifications are investigated using advanced spectroscopic and spectrometric techniques, as well as mechanical testing and surface mapping. The impact of these characterizations will provide valuable perspective to researchers in materials science. Understanding the changes to the structure and properties of this class of thin films, which can be induced through various mechanisms, will allow future researchers to refine these films towards technological applications in areas of hard coatings, electronics and photonics.

Continuum kinetic modeling of the tokamak plasma edge

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

Dorf, M. A.; Dorr, M. R.; Hittinger, J. A.

2016-05-15

The first 4D (axisymmetric) high-order continuum gyrokinetic transport simulations that span the magnetic separatrix of a tokamak are presented. The modeling is performed with the COGENT code, which is distinguished by fourth-order finite-volume discretization combined with mapped multiblock grid technology to handle the strong anisotropy of plasma transport and the complex X-point divertor geometry with high accuracy. The calculations take into account the effects of fully nonlinear Fokker-Plank collisions, electrostatic potential variations, and anomalous radial transport. Topics discussed include: (a) ion orbit loss and the associated toroidal rotation and (b) edge plasma relaxation in the presence of anomalous radial transport.

Cardiovascular and Metabolic Consequences of Testosterone Supplements in Young and Old Male Spontaneously Hypertensive Rats: Implications for Testosterone Supplements in Men.

PubMed

Dalmasso, Carolina; Patil, Chetan N; Yanes Cardozo, Licy L; Romero, Damian G; Maranon, Rodrigo O

2017-10-17

The safety of testosterone supplements in men remains unclear. In the present study, we tested the hypothesis that in young and old male spontaneously hypertensive rats (SHR), long-term testosterone supplements increase blood pressure and that the mechanism is mediated in part by activation of the renin-angiotensin system. In untreated males, serum testosterone exhibited a sustained decrease after 5 months of age, reaching a nadir by 18 to 22 months of age. The reductions in serum testosterone were accompanied by an increase in body weight until very old age (18 months). Testosterone supplements were given for 6 weeks to young (12 weeks-YMSHR) and old (21-22 months-OMSHR) male SHR that increased serum testosterone by 2-fold in young males and by 4-fold in old males. Testosterone supplements decreased body weight, fat mass, lean mass, and plasma leptin, and increased plasma estradiol in YMSHR but had no effect in OMSHR. Mean arterial pressure (MAP) was significantly higher in OMSHR than in YMSHR and testosterone supplements decreased MAP in OMSHR, but significantly increased MAP in YMSHR. Enalapril, the angiotensin-converting enzyme inhibitor, reduced MAP in both control and testosterone-supplemented YMSHR, but had a greater effect on MAP in testosterone-treated rats, suggesting the mechanism responsible for the increase in MAP in YMSHR is mediated at least in part by activation of the renin-angiotensin system. Taken together with previous studies, these data suggest that testosterone supplements may have differential effects on men depending on age, cardiovascular and metabolic status, and dose and whether given long-term or short-term. © 2017 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley.

Spectroscopic Ellipsometry Studies of Thin Film a-Si:H Solar Cell Fabrication by Multichamber Deposition in the n-i-p Substrate Configuration

NASA Astrophysics Data System (ADS)

Dahal, Lila Raj

Real time spectroscopic ellipsometry (RTSE), and ex-situ mapping spectroscopic ellipsometry (SE) are powerful characterization techniques capable of performance optimization and scale-up evaluation of thin film solar cells used in various photovoltaics technologies. These non-invasive optical probes employ multichannel spectral detection for high speed and provide high precision parameters that describe (i) thin film structure, such as layer thicknesses, and (ii) thin film optical properties, such as oscillator variables in analytical expressions for the complex dielectric function. These parameters are critical for evaluating the electronic performance of materials in thin film solar cells and also can be used as inputs for simulating their multilayer optical performance. In this Thesis, the component layers of thin film hydrogenated silicon (Si:H) solar cells in the n-i-p or substrate configuration on rigid and flexible substrate materials have been studied by RTSE and ex-situ mapping SE. Depositions were performed by magnetron sputtering for the metal and transparent conducting oxide contacts and by plasma enhanced chemical vapor deposition (PECVD) for the semiconductor doped contacts and intrinsic absorber layers. The motivations are first to optimize the thin film Si:H solar cell in n-i-p substrate configuration for single-junction small-area dot cells and ultimately to scale-up the optimized process to larger areas with minimum loss in device performance. Deposition phase diagrams for both i- and p -layers on 2" x 2" rigid borosilicate glass substrate were developed as functions of the hydrogen-to-silane flow ratio in PECVD. These phase diagrams were correlated with the performance parameters of the corresponding solar cells, fabricated in the Cr/Ag/ZnO/n/i/ p/ITO structure. In both cases, optimization was achieved when the layers were deposited in the protocrystalline phase. Identical solar cell structures were fabricated on 6" x 6" borosilicate glass with 256 cells followed by ex-situ mapping SE on each cell to achieve better statistics for solar cell optimization by correlating local structural parameters with solar cell parameters. Solar cells of similar structure were also fabricated on flexible polymer substrates in the roll-to-roll configuration. In this configuration as well, RTSE was demonstrated as an effective process monitoring and control tool for thin film photovoltaics.

A financial market model with two discontinuities: Bifurcation structures in the chaotic domain

NASA Astrophysics Data System (ADS)

Panchuk, Anastasiia; Sushko, Iryna; Westerhoff, Frank

2018-05-01

We continue the investigation of a one-dimensional piecewise linear map with two discontinuity points. Such a map may arise from a simple asset-pricing model with heterogeneous speculators, which can help us to explain the intricate bull and bear behavior of financial markets. Our focus is on bifurcation structures observed in the chaotic domain of the map's parameter space, which is associated with robust multiband chaotic attractors. Such structures, related to the map with two discontinuities, have been not studied before. We show that besides the standard bandcount adding and bandcount incrementing bifurcation structures, associated with two partitions, there exist peculiar bandcount adding and bandcount incrementing structures involving all three partitions. Moreover, the map's three partitions may generate intriguing bistability phenomena.

Report on Research for Period January 1983-December 1984

DTIC Science & Technology

1985-06-28

WORK UNIT ELEMENT NO. NO. NO. NO 11. TITLE (Include Security Clasification) 9993 XX Report on Research 12. PERSONAL AUTHOR(S) Alice B. McGinty...4rborne Measure- ments -Auroral Soundino Rocket Probes Infrared Atmospnerc Modeling Appendices A AFGL Projects by Program Element 203 B AFGL Rocket Program...obtained a strip map of the earth’s of neutral winds and ionospheric plasma, ionosphere seen from the polar- orbiting electric field-driven plasma drifts, ion

Auroral magnetosphere-ionosphere coupling: A brief topical review

NASA Technical Reports Server (NTRS)

Chiu, Y. T.; Schulz, M.; Cornwall, J. M.

1979-01-01

Auroral arcs result from the acceleration and precipitation of magnetospheric plasma in narrow regions characterized by strong electric fields both perpendicular and parallel to the earth's magnetic field. The various mechanisms that were proposed for the origin of such strong electric fields are often complementary Such mechanisms include: (1) electrostatic double layers; (2) double reverse shock; (3) anomalous resistivity; (4) magnetic mirroring of hot plasma; and (5) mapping of the magnetospheric-convection electric field through an auroral discontinuity.

Atmospheric-pressure plasma activation and surface characterization on polyethylene membrane separator

NASA Astrophysics Data System (ADS)

Tseng, Yu-Chien; Li, Hsiao-Ling; Huang, Chun

2017-01-01

The surface hydrophilic activation of a polyethylene membrane separator was achieved using an atmospheric-pressure plasma jet. The surface of the atmospheric-pressure-plasma-treated membrane separator was found to be highly hydrophilic realized by adjusting the plasma power input. The variations in membrane separator chemical structure were confirmed by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. Chemical analysis showed newly formed carbonyl-containing groups and high surface concentrations of oxygen-containing species on the atmospheric-pressure-plasma-treated polymeric separator surface. It also showed that surface hydrophilicity primarily increased from the polar component after atmospheric-pressure plasma treatment. The surface and pore structures of the polyethylene membrane separator were examined by scanning electron microscopy, revealing a slight alteration in the pore structure. As a result of the incorporation of polar functionalities by atmospheric-pressure plasma activation, the electrolyte uptake and electrochemical impedance of the atmospheric-pressure-plasma-treated membrane separator improved. The investigational results show that the separator surface can be controlled by atmospheric-pressure plasma surface treatment to tailor the hydrophilicity and enhance the electrochemical performance of lithium ion batteries.

Unraveling the Origin of Overionized Plasma in the Galactic Supernova Remnant W49B

NASA Astrophysics Data System (ADS)

Pearson, Sarah; Lopez, L. A.; Ramirez-Ruiz, E.; Castro, D.; Yamaguchi, H.; Slane, P. O.; Smith, R. K.

2013-04-01

In this presentation, I present maps of overionized plasma in the Galactic supernova remnant (SNR) W49B based on a recent 220 ks Chandra Advanced CCD Imaging Spectrometer observation. Overionized plasmas (those where ions are stripped of more electrons than they should be for a given electron temperature) have been found recently in several SNRs, and the physical origin of the rapid cooling necessary to produce them remains uncertain. To assess the cooling scenario responsible for overionization, we performed a spatially-resolved spectroscopic analysis of W49B, measuring the elec- tron temperature by modeling the bremsstrahlung continuum and comparing it to the temperature given by the flux ratio of He-like to H-like lines of sulfur, argon, and calcium. Using these results, we find that the west region of W49B is the most overionized, with a gradient of increasing overionization from East to West. As the ejecta expansion is impeded by molecular material in the east but not in the west, our overionization maps suggest the dominant cooling mechanism is adiabatic expansion of the hot plasma instead of thermal conduction. Furthermore, we find calcium has the greatest degree of overionization relative to argon and sulfur; this result arises because calcium has a longer recombination timescale. Thus, we caution that measurement of overionization is dependent on which elements one employs in their line ratio analysis.

Coupling extended magnetohydrodynamic fluid codes with radiofrequency ray tracing codes for fusion modeling

NASA Astrophysics Data System (ADS)

Jenkins, Thomas G.; Held, Eric D.

2015-09-01

Neoclassical tearing modes are macroscopic (L ∼ 1 m) instabilities in magnetic fusion experiments; if unchecked, these modes degrade plasma performance and may catastrophically destroy plasma confinement by inducing a disruption. Fortunately, the use of properly tuned and directed radiofrequency waves (λ ∼ 1 mm) can eliminate these modes. Numerical modeling of this difficult multiscale problem requires the integration of separate mathematical models for each length and time scale (Jenkins and Kruger, 2012 [21]); the extended MHD model captures macroscopic plasma evolution while the RF model tracks the flow and deposition of injected RF power through the evolving plasma profiles. The scale separation enables use of the eikonal (ray-tracing) approximation to model the RF wave propagation. In this work we demonstrate a technique, based on methods of computational geometry, for mapping the ensuing RF data (associated with discrete ray trajectories) onto the finite-element/pseudospectral grid that is used to model the extended MHD physics. In the new representation, the RF data can then be used to construct source terms in the equations of the extended MHD model, enabling quantitative modeling of RF-induced tearing mode stabilization. Though our specific implementation uses the NIMROD extended MHD (Sovinec et al., 2004 [22]) and GENRAY RF (Smirnov et al., 1994 [23]) codes, the approach presented can be applied more generally to any code coupling requiring the mapping of ray tracing data onto Eulerian grids.

Unified first wall - blanket structure for plasma device applications

DOEpatents

Gruen, D.M.

A plasma device is described for use in controlling nuclear reactions within the plasma including a first wall and blanket formed in a one-piece structure composed of a solid solution containing copper and lithium and melting above about 500/sup 0/C.

Shock structures in a strongly coupled self-gravitating opposite-polarity dust plasma

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

Mamun, A. A.; Schlickeiser, R.

2016-03-15

A strongly coupled, self-gravitating, opposite-polarity dust plasma (containing strongly coupled inertial positive and negative dust fluids, and inertialess weakly coupled ions) is considered. The generalized hydrodynamic model and the reductive perturbation method are employed to examine the possibility for the formation of the dust-acoustic (DA) shock structures in such an opposite-polarity dust plasma. It has been shown that the strong correlation among charged dust is a source of dissipation and is responsible for the formation of the DA shock structures in such the opposite-polarity dust plasma medium. The parametric regimes for the existence of the DA shock structures (associated withmore » electrostatic and gravitational potentials) and their basic properties (viz., polarity, amplitude, width, and speed) are found to be significantly modified by the combined effects of positively charged dust component, self-gravitational field, and strong correlation among charged dust. The implications of our results in different space plasma environments and laboratory plasma devices are briefly discussed.« less

Quasi-discrete particle motion in an externally imposed, ordered structure in a dusty plasma at high magnetic field

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

Thomas, Edward, E-mail: etjr@auburn.edu; Konopka, Uwe; Lynch, Brian

Dusty plasmas have been studied in argon, radio frequency (rf) glow discharge plasmas at magnetic fields up to 2.5 T where the electrons and ions are strongly magnetized. Plasmas are generated between two parallel plate electrodes where the lower, powered electrode is solid and the upper electrode supports a dual mesh consisting of #24 brass and #30 aluminum wire cloth. In this experiment, we study the formation of imposed ordered structures and particle dynamics as a function of magnetic field. Through observations of trapped particles and the quasi-discrete (i.e., “hopping”) motion of particles between the trapping locations, it is possible tomore » make a preliminary estimate of the potential structure that confines the particles to a grid structure in the plasma. This information is used to gain insight into the formation of the imposed grid pattern of the dust particles in the plasma.« less

Enhancing the usability and performance of structured association mapping algorithms using automation, parallelization, and visualization in the GenAMap software system

PubMed Central

2012-01-01

Background Structured association mapping is proving to be a powerful strategy to find genetic polymorphisms associated with disease. However, these algorithms are often distributed as command line implementations that require expertise and effort to customize and put into practice. Because of the difficulty required to use these cutting-edge techniques, geneticists often revert to simpler, less powerful methods. Results To make structured association mapping more accessible to geneticists, we have developed an automatic processing system called Auto-SAM. Auto-SAM enables geneticists to run structured association mapping algorithms automatically, using parallelization. Auto-SAM includes algorithms to discover gene-networks and find population structure. Auto-SAM can also run popular association mapping algorithms, in addition to five structured association mapping algorithms. Conclusions Auto-SAM is available through GenAMap, a front-end desktop visualization tool. GenAMap and Auto-SAM are implemented in JAVA; binaries for GenAMap can be downloaded from http://sailing.cs.cmu.edu/genamap. PMID:22471660

Method for removing atomic-model bias in macromolecular crystallography

DOEpatents

Terwilliger, Thomas C [Santa Fe, NM

2006-08-01

Structure factor bias in an electron density map for an unknown crystallographic structure is minimized by using information in a first electron density map to elicit expected structure factor information. Observed structure factor amplitudes are combined with a starting set of crystallographic phases to form a first set of structure factors. A first electron density map is then derived and features of the first electron density map are identified to obtain expected distributions of electron density. Crystallographic phase probability distributions are established for possible crystallographic phases of reflection k, and the process is repeated as k is indexed through all of the plurality of reflections. An updated electron density map is derived from the crystallographic phase probability distributions for each one of the reflections. The entire process is then iterated to obtain a final set of crystallographic phases with minimum bias from known electron density maps.

Dust remobilization in fusion plasmas under steady state conditions

NASA Astrophysics Data System (ADS)

Tolias, P.; Ratynskaia, S.; De Angeli, M.; De Temmerman, G.; Ripamonti, D.; Riva, G.; Bykov, I.; Shalpegin, A.; Vignitchouk, L.; Brochard, F.; Bystrov, K.; Bardin, S.; Litnovsky, A.

2016-02-01

The first combined experimental and theoretical studies of dust remobilization by plasma forces are reported. The main theoretical aspects of remobilization in fusion devices under steady state conditions are analyzed. In particular, the dominant role of adhesive forces is highlighted and generic remobilization conditions—direct lift-up, sliding, rolling—are formulated. A novel experimental technique is proposed, based on controlled adhesion of dust grains on tungsten samples combined with detailed mapping of the dust deposition profile prior and post plasma exposure. Proof-of-principle experiments in the TEXTOR tokamak and the EXTRAP-T2R reversed-field pinch are presented. The versatile environment of the linear device Pilot-PSI allowed for experiments with different magnetic field topologies and varying plasma conditions that were complemented with camera observations.

Geological Mapping Uses Landsat 4-5TM Satellite Data in Manlai Soum of Omnogovi Aimag

NASA Astrophysics Data System (ADS)

Norovsuren, B.

2014-12-01

Author: Bayanmonkh N1, Undram.G1, Tsolmon.R2, Ariunzul.Ya1, Bayartungalag B31 Environmental Research Information and Study Center 2NUM-ITC-UNESCO Space Science and Remote Sensing International Laboratory, National University of Mongolia 3Geology and Hydrology School, Korea University KEY WORDS: geology, mineral resources, fracture, structure, lithologyABSTRACTGeologic map is the most important map for mining when it does exploration job. In Mongolia geological map completed by Russian geologists which is done by earlier technology. Those maps doesn't satisfy for present requirements. Thus we want to study improve geological map which includes fracture, structural map and lithology use Landsat TM4-5 satellite data. If we can produce a geological map from satellite data with more specification then geologist can explain or read mineralogy very easily. We searched all methodology and researches of every single element of geological mapping. Then we used 3 different remote sensing methodologies to produce structural and lithology and fracture map based on geographic information system's softwares. There can be found a visible lithology border improvement and understandable structural map and we found fracture of the Russian geological map has a lot of distortion. The result of research geologist can read mineralogy elements very easy and discovered 3 unfound important elements from satellite image.

Structure and shale gas production patterns from eastern Kentucky field

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

Shumaker, R.C.

Computer-derived subsurface structure, isopach, and gas-flow maps, based on 4000 drillers logs, have been generated for eastern Kentucky under a project sponsored by the Gas Research Institute. Structure maps show low-relief flextures related to basement structure. Some structures have been mapped at the surface, others have not. Highest final open-flow (fof) of shale gas from wells in Martin County follow a structural low between (basement) anticlines. From there, elevated gas flows (fof) extend westward along the Warfield monocline to Floyd County where the high flow (fof) trend extends southward along the Floyd County channel. In Knott County, the number ofmore » wells with high gas flow (fof) decreases abruptly. The center of highest gas flow (fof) in Floyd County spreads eastward to Pike County, forming a triangular shaped area of high production (fof). The center of highest gas flow (fof) is in an area where possible (basement) structure trends intersect and where low-relief surface folds (probably detached structure) were mapped and shown on the 1922 version of the Floyd County structure map. Modern regional maps, based on geophysical logs from widely spaced wells, do not define the low-relief structures that have been useful in predicting gas flow trends. Detailed maps based on drillers logs can be misleading unless carefully edited. Comparative analysis of high gas flows (fof) and 10-year cumulative production figures in a small area confirms that there is a relationship between gas flow (fof) values and long-term cumulative production.« less

Multi-walled carbon nanotubes injure the plasma membrane of macrophages

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

Hirano, Seishiro; Kanno, Sanae; Furuyama, Akiko

2008-10-15

Carbon nanotubes (CNTs) are emerging nanotechnology materials which are likely to be mass-produced in the near future. However, prior to mass-production, certain health-related concerns should first be addressed. For example, when inhaled, the thin-fibrous shape and the biopersistent characteristics of CNTs may cause pulmonary diseases, in a manner similar to asbestos. In the present study, mouse macrophages (J774.1) were exposed to highly-purified multi-walled CNTs (MWCNTs, 67 nm) or to UICC crocidolite in order to evaluate the toxicity of these nano-size fibers. The cytotoxicity of MWCNTs was found to be higher than that of crocidolite. The toxic effect of MWCNTs wasmore » not affected by N-acetylcysteine, an antioxidant, or buthionine sulfoximine, a glutathione synthesis inhibitor. cDNA microarray analyses suggested that the cytotoxicity of MWCNTs could not be explained satisfactorily by either an increase or decrease of gene expression, although mRNA levels of some cytokines were slightly increased by MWCNTs. Moreover, MWCNTs did not significantly activate either MAP kinases such as ERK, JNK and p38, nor common apoptosis pathways such as caspase 3 and PARP. Electron microscopic studies indicated that MWCNTs associate with the plasma membrane of macrophages and disrupt the integrity of the membrane. Several proteins were found to adsorb onto MWCNTs when MWCNT-exposed macrophages were gently lysed. One of these proteins was macrophage receptor with collagenous structure (MARCO). MARCO-transfected CHO-K1 cells associated with MWCNTs more rapidly than mock-transfected cells. These results indicate that MWCNTs probably trigger cytotoxic effects in phagocytotic cells by reacting with MARCO on the plasma membrane and rupturing the plasma membrane.« less

Radial and local time structure of the Saturnian ring current, revealed by Cassini

NASA Astrophysics Data System (ADS)

Sergis, N.; Jackman, C. M.; Thomsen, M. F.; Krimigis, S. M.; Mitchell, D. G.; Hamilton, D. C.; Dougherty, M. K.; Krupp, N.; Wilson, R. J.

2017-02-01

We analyze particle and magnetic field data obtained between July 2004 and December 2013 in the equatorial magnetosphere of Saturn, by the Cassini spacecraft. The radial and local time distribution of the total (thermal and suprathermal) particle pressure and total plasma beta (ratio of particle to magnetic pressure) over radial distances from 5 to 16 Saturn radii (RS = 60,258 km) is presented. The average azimuthal current density Jϕ and its separate components (inertial, pressure gradient, and anisotropy) are computed as a function of radial distance and local time and presented as equatorial maps. We explore the relative contribution of different physical mechanisms that drive the ring current at Saturn. Results show that (a) the particle pressure is controlled by thermal plasma inside of 8 RS and by the hot ions beyond 12 RS, exhibiting strong local time asymmetry with higher pressures measured at the dusk and night sectors; (b) the plasma beta increases with radial distance and remains >1 beyond 8-10 RS for all local times; (c) the ring current is asymmetric in local time and forms a maximum region between 7 and 13 RS, with values up to 100-115 pA/m2; and (d) the ring current is inertial everywhere inside of 7 RS, exhibits a mixed nature between 7 and 11 RS and is pressure gradient driven beyond 11 RS, with the exception of the noon sector where the mixed nature persists. In the dawn sector, it appears strongly pressure gradient driven for a wider range of radial distance, consistent with fast return flow of hot, tenuous magnetospheric plasma following tail reconnection.

The plasma environment inside geostationary orbit: A Van Allen Probes HOPE survey

PubMed Central

Larsen, Brian A.; Thomsen, Michelle F.; Skoug, Ruth M.; Reeves, Geoffrey D.; Denton, Michael H.; Friedel, Reinhard H. W.; Funsten, Herbert O.; Goldstein, Jerry; Henderson, Michael G.; Jahn, Jörg‐Micha; MacDonald, Elizabeth A.; Olson, David K.

2017-01-01

Abstract The two full precessions in local time completed by the Van Allen Probes enable global specification of the near‐equatorial inner magnetosphere plasma environment. Observations by the Helium‐Oxygen‐Proton‐Electron (HOPE) mass spectrometers provide detailed insight into the global spatial distribution of electrons, H+, He+, and O+. Near‐equatorial omnidirectional fluxes and abundance ratios at energies 0.1–30 keV are presented for 2 ≤ L ≤ 6 as a function of L shell, magnetic local time (MLT), and geomagnetic activity. We present a new tool built on the UBK modeling technique for classifying plasma sheet particle access to the inner magnetosphere. This new tool generates access maps for particles of constant energy for more direct comparison with in situ measurements, rather than the traditional constant μ presentation typically associated with UBK. We present for the first time inner magnetosphere abundances of O+ flux relative to H+ flux as a function of Kp, L, MLT, and energy. At L = 6, the O+/H+ ratio increases with increasing Kp, consistent with previous results. However, at L < 5 the O+/H+ ratio generally decreases with increasing Kp. We identify a new “afternoon bulge” plasma population enriched in 10 keV O+ and superenriched in 10 keV He+ that is present during quiet/moderate geomagnetic activity (Kp < 5) at ~1100–2000 MLT and L shell 2–4. Drift path modeling results are consistent with the narrow energy and approximate MLT location of this enhancement, but the underlying physics describing its formation, structure, and depletion during higher geomagnetic activity are currently not understood. PMID:29214118

The plasma environment inside geostationary orbit: A Van Allen Probes HOPE survey.

PubMed

Fernandes, Philip A; Larsen, Brian A; Thomsen, Michelle F; Skoug, Ruth M; Reeves, Geoffrey D; Denton, Michael H; Friedel, Reinhard H W; Funsten, Herbert O; Goldstein, Jerry; Henderson, Michael G; Jahn, Jörg-Micha; MacDonald, Elizabeth A; Olson, David K

2017-09-01

The two full precessions in local time completed by the Van Allen Probes enable global specification of the near-equatorial inner magnetosphere plasma environment. Observations by the Helium-Oxygen-Proton-Electron (HOPE) mass spectrometers provide detailed insight into the global spatial distribution of electrons, H + , He + , and O + . Near-equatorial omnidirectional fluxes and abundance ratios at energies 0.1-30 keV are presented for 2 ≤ L ≤ 6 as a function of L shell, magnetic local time (MLT), and geomagnetic activity. We present a new tool built on the UBK modeling technique for classifying plasma sheet particle access to the inner magnetosphere. This new tool generates access maps for particles of constant energy for more direct comparison with in situ measurements, rather than the traditional constant μ presentation typically associated with UBK. We present for the first time inner magnetosphere abundances of O + flux relative to H + flux as a function of Kp, L, MLT, and energy. At L = 6, the O + /H + ratio increases with increasing Kp, consistent with previous results. However, at L < 5 the O + /H + ratio generally decreases with increasing Kp. We identify a new "afternoon bulge" plasma population enriched in 10 keV O + and superenriched in 10 keV He + that is present during quiet/moderate geomagnetic activity (Kp < 5) at ~1100-2000 MLT and L shell 2-4. Drift path modeling results are consistent with the narrow energy and approximate MLT location of this enhancement, but the underlying physics describing its formation, structure, and depletion during higher geomagnetic activity are currently not understood.

Rabenosyn-5 and EHD1 interact and sequentially regulate protein recycling to the plasma membrane.

PubMed

Naslavsky, Naava; Boehm, Markus; Backlund, Peter S; Caplan, Steve

2004-05-01

EHD1 has been implicated in the recycling of internalized proteins to the plasma membrane. However, the mechanism by which EHD1 mediates recycling and its relationship to Rab-family-controlled events has yet to be established. To investigate further the mode of EHD1 action, we sought to identify novel interacting partners. GST-EHD1 was used as bait to isolate a approximately 120-kDa species from bovine and murine brain cytosol, which was identified by mass spectrometry as the divalent Rab4/Rab5 effector Rabenosyn-5. We mapped the sites of interaction to the EH domain of EHD1, and the first two of five NPF motifs of Rabenosyn-5. Immunofluorescence microscopy studies revealed that EHD1 and Rabenosyn-5 partially colocalize to vesicular and tubular structures in vivo. To address the functional roles of EHD1 and Rabenosyn-5, we first demonstrated that RNA interference (RNAi) dramatically reduced the level of expression of each protein, either individually or in combination. Depletion of either EHD1 or Rabenosyn-5 delayed the recycling of transferrin and major histocompatibility complex class I to the plasma membrane. However, whereas depletion of EHD1 caused the accumulation of internalized cargo in a compact juxtanuclear compartment, Rabenosyn-5-RNAi caused its retention within a dispersed peripheral compartment. Simultaneous RNAi depletion of both proteins resulted in a similar phenotype to that observed with Rabenosyn-5-RNAi alone, suggesting that Rabenosyn-5 acts before EHD1 in the regulation of endocytic recycling. Our studies suggest that Rabenosyn-5 and EHD1 act sequentially in the transport of proteins from early endosomes to the endosomal recycling compartment and back to the plasma membrane.

Investigating the dynamics of laser induced sparks in atmospheric helium using Rayleigh and Thomson scattering

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

Nedanovska, E.; Nersisyan, G.; Lewis, C. L. S.

2015-01-07

We have used optical Rayleigh and Thomson scattering to investigate the expansion dynamics of laser induced plasma in atmospheric helium and to map its electron parameters both in time and space. The plasma is created using 9 ns duration, 140 mJ pulses from a Nd:YAG laser operating at 1064 nm, focused with a 10 cm focal length lens, and probed with 7 ns, 80 mJ, and 532 nm Nd:YAG laser pulses. Between 0.4 μs and 22.5 μs after breakdown, the electron density decreases from 3.3 × 10{sup 17 }cm{sup −3} to 9 × 10{sup 13 }cm{sup −3}, while the temperature drops from 3.2 eV to 0.1 eV. Spatially resolved Thomson scattering data recorded up to 17.5 μs revealmore » that during this time the laser induced plasma expands at a rate given by R ∼ t{sup 0.4} consistent with a non-radiative spherical blast wave. This data also indicate the development of a toroidal structure in the lateral profile of both electron temperature and density. Rayleigh scattering data show that the gas density decreases in the center of the expanding plasma with a central scattering peak reemerging after about 12 μs. We have utilized a zero dimensional kinetic global model to identify the dominant particle species versus delay time and this indicates that metastable helium and the He{sub 2}{sup +} molecular ion play an important role.« less

Geology of the Cape Mendocino, Eureka, Garberville, and Southwestern Part of the Hayfork 30 x 60 Minute Quadrangles and Adjacent Offshore Area, Northern California

USGS Publications Warehouse

McLaughlin, Robert J.; Ellen, S.D.; Blake, M.C.; Jayko, Angela S.; Irwin, W.P.; Aalto, K.R.; Carver, G.A.; Clarke, S.H.; Barnes, J.B.; Cecil, J.D.; Cyr, K.A.

2000-01-01

Introduction These geologic maps and accompanying structure sections depict the geology and structure of much of northwestern California and the adjacent continental margin. The map area includes the Mendocino triple junction, which is the juncture of the North American continental plate with two plates of the Pacific ocean basin. The map area also encompasses major geographic and geologic provinces of northwestern California. The maps incorporate much previously unpublished geologic mapping done between 1980 and 1995, as well as published mapping done between about 1950 and 1978. To construct structure sections to mid-crustal depths, we integrate the surface geology with interpretations of crustal structure based on seismicity, gravity and aeromagnetic data, offshore structure, and seismic reflection and refraction data. In addition to describing major geologic and structural features of northwestern California, the geologic maps have the potential to address a number of societally relevant issues, including hazards from earthquakes, landslides, and floods and problems related to timber harvest, wildlife habitat, and changing land use. All of these topics will continue to be of interest in the region, as changing land uses and population density interact with natural conditions. In these interactions, it is critical that the policies and practices affecting man and the environment integrate an adequate understanding of the geology. This digital map database, compiled from previously published and unpublished data, and new mapping by the authors, represents the general distribution of bedrock and surficial deposits in the mapped area. Together with the accompanying text file (ceghmf.ps, ceghmf.pdf, ceghmf.txt), it provides current information on the geologic structure and stratigraphy of the area covered. The database delineates map units that are identified by general age and lithology following the stratigraphic nomenclature of the U.S. Geological Survey. The scale of the source maps limits the spatial resolution (scale) of the database to 1:100,000 or smaller.

Electrode assemblies, plasma generating apparatuses, and methods for generating plasma

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

Kong, Peter C.; Grandy, Jon D.; Detering, Brent A.

Electrode assemblies for plasma reactors include a structure or device for constraining an arc endpoint to a selected area or region on an electrode. In some embodiments, the structure or device may comprise one or more insulating members covering a portion of an electrode. In additional embodiments, the structure or device may provide a magnetic field configured to control a location of an arc endpoint on the electrode. Plasma generating modules, apparatus, and systems include such electrode assemblies. Methods for generating a plasma include covering at least a portion of a surface of an electrode with an electrically insulating membermore » to constrain a location of an arc endpoint on the electrode. Additional methods for generating a plasma include generating a magnetic field to constrain a location of an arc endpoint on an electrode.« less

Effects of oxygen plasma treatment power on Aramid fiber III/BMI composite humidity resistance properties

NASA Astrophysics Data System (ADS)

Wang, Jing; Shi, Chen; Feng, Jiayue; Long, Xi; Meng, Lingzhi; Ren, Hang

2018-01-01

The effects of oxygen plasma treatment power on Aramid Fiber III chemical structure and its reinforced bismaleimides (BMI) composite humidity resistance properties were investigated in this work. The aramid fiber III chemical structure under different plasma treatment power were measured by FTIR. The composite bending strength and interlinear shear strength with different plasma treatment power before and after absorption water were tested respectively. The composite rupture morphology was observed by SEM. The FTIR results showed that oxygen plasma treatment do not change the fiber bulk chemical structure. The composite humidity resistance of bending strength and interlinear shear strength are similar for untreated and plasma treated samples. The retention rate of composite bending strength and interlinear shear strength are about 75% and 94%, respectively. The composite rupture mode turns to be the fiber failure after water absorption.

Plasma modification of spoof plasmon propagation along metamaterial-air interfaces

NASA Astrophysics Data System (ADS)

Lee, R.; Wang, B.; Cappelli, M. A.

2017-12-01

We report on measurements of the shift in resonance frequency of "spoof" surface plasmon polariton propagation along a 2-D metamaterial slow-wave structure induced by a gaseous plasma near the metamaterial/air interface. A transmission line circuit model for the metamaterial structure interprets the introduction of a plasma as a decrease in unit cell capacitance, causing a shift in the plasmon dispersion to higher frequency. We show through simulations and experiments that the effects of this shift at the resonance frequency and attenuation below and above resonance depend on the plasma density. The shifts recorded experimentally are small owing to the low plasma densities generated near the structure, ˜ 10 11 cm - 3 , but simulations show that a shift of ˜ 3 % of the resonance frequency can be generated at plasma densities of ˜ 10 12 cm - 3 .

Spatial structures arising along a surface wave produced plasma column: an experimental study

NASA Astrophysics Data System (ADS)

Atanassov, V.; Mateev, E.

2007-04-01

The formation of spatial structures in high-frequency and microwave discharges has been known for several decades. Nevertheless it still raises increased interest, probably due to the variety of the observed phenomena and the lack of adequate and systematic theoretical interpretation. In this paper we present preliminary results on observation of spatial structures appearing along a surface wave sustained plasma column. The experiments have been performed in noble gases (xenon and neon) at low to intermediate pressure and the surface wave has been launched by a surfatron. Under these conditions we have observed and documented: i) appearance of stationary plasma rings; ii) formation of standing-wave striationlike patterns; iii) contraction of the plasma column; iv) plasma column transition into moving plasma balls and filaments. Some of the existing theoretical considerations of these phenomena are reviewed and discussed.

Combustion flame-plasma hybrid reactor systems, and chemical reactant sources

DOEpatents

Kong, Peter C

2013-11-26

Combustion flame-plasma hybrid reactor systems, chemical reactant sources, and related methods are disclosed. In one embodiment, a combustion flame-plasma hybrid reactor system comprising a reaction chamber, a combustion torch positioned to direct a flame into the reaction chamber, and one or more reactant feed assemblies configured to electrically energize at least one electrically conductive solid reactant structure to form a plasma and feed each electrically conductive solid reactant structure into the plasma to form at least one product is disclosed. In an additional embodiment, a chemical reactant source for a combustion flame-plasma hybrid reactor comprising an elongated electrically conductive reactant structure consisting essentially of at least one chemical reactant is disclosed. In further embodiments, methods of forming a chemical reactant source and methods of chemically converting at least one reactant into at least one product are disclosed.

Electrode assemblies, plasma apparatuses and systems including electrode assemblies, and methods for generating plasma

DOEpatents

Kong, Peter C; Grandy, Jon D; Detering, Brent A; Zuck, Larry D

2013-09-17

Electrode assemblies for plasma reactors include a structure or device for constraining an arc endpoint to a selected area or region on an electrode. In some embodiments, the structure or device may comprise one or more insulating members covering a portion of an electrode. In additional embodiments, the structure or device may provide a magnetic field configured to control a location of an arc endpoint on the electrode. Plasma generating modules, apparatus, and systems include such electrode assemblies. Methods for generating a plasma include covering at least a portion of a surface of an electrode with an electrically insulating member to constrain a location of an arc endpoint on the electrode. Additional methods for generating a plasma include generating a magnetic field to constrain a location of an arc endpoint on an electrode.

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

Munsat, Tobin

Overview of University of Colorado Efforts: The University of Colorado group has focused on two primary fronts during the grant period: development of a variety of multi-point diagnostic and/or imaging analysis techniques, and momentum-transport related experiments on a variety of devices (NSTX at PPPL, CSDX at UCSD, LAPD at UCLA, DIII-D at GA). Experimental work has taken advantage of several diagnostic instruments, including fast-framing cameras for imaging of electron density fluctuations (either directly or using injected gas puffs), ECEI for imaging of electron temperature fluctuations, and multi-tipped Langmuir and magnetic probes for corroborating measurements of Reynolds and Maxwell stresses. Modemore » Characterization in CSDX: We have performed a series of experiments at the CSDX linear device at UCSD, in collaboration with Center PI G. Tynan's group. The experiments included a detailed study of velocity estimation techniques, including direct comparisons between Langmuir probes and image-based velocimetry from fast-framing camera data. We used the camera data in a second set of studies to identify the spatial and spectral structure of coherent modes, which illuminates wave behavior to a level of detail previously unavailable, and enables direct comparison of dispersion curves to theoretical estimates. In another CSDX study, similar techniques were used to demonstrate a controlled transition from nonlinearly coupled discrete eigenmodes to fully developed broadband turbulence. The axial magnetic field was varied from 40-240 mT, which drove the transition. At low magnetic fields, the plasma is dominated by drift waves. As the magnetic field is increased, a strong potential gradient at the edge introduces an ExB shear-driven instability. At the transition, another mode with signatures of a rotation-induced Rayleigh–Taylor instability appears at the central plasma region. Concurrently, large axial velocities were found in the plasma core. For larger magnetic fields, all of the instabilities co-exist, leading to rich plasma dynamics and fully developed broadband turbulence. Edge-Turbulence and Flow Experiments in NSTX: A series of Gas Puff Imaging (GPI) observations on NSTX revealed a quasi-periodic oscillation in the plasma edge preceding the L-H transition in a limited set of neutral beam heated plasmas. These ~3 kHz flow oscillations exhibit both long wavelength and long correlation lengths, suggesting they are zonal-flow-like. The flow oscillations are strongly correlated with modulations of the level of edge turbulence, thus the system appears to undergo a predator--prey-type limit-cycle preceding the L-H transition. However, a clear trigger for the L-H transition was not observed. Reynolds stress profiles were obtained directly from image velocimetry for L-mode periods ELM-Precursor Studies in NSTX: A separate study based on NSTX-GPI data captured the two-dimensional evolution of edge-localized mode (ELM) precursors. Precursor events were observed preceding ELMs and ELM-induced H–L back-transitions in radio-frequency heated H-mode plasmas, and the growth of the precursor mode through the ELM filamentation was imaged in the plane perpendicular to the local B-field. Strong edge intensity modulations appeared to propagate in the electron diamagnetic direction while steadily drifting radially outwards. Intensity fluctuations were observed at frequencies around 20 kHz and wavenumbers of 0.05-0.2 cm -1. Upon growing to a trigger point, precursor fluctuations were seen to form filamentary structures and move into the scrape-off layer (SOL) explosively with radial velocities peaking at 8 km/s. Once in the SOL, filaments reverse their propagation direction and travel in the ion diamagnetic direction. Edge intensity fluctuations were strongly correlated with magnetic signals from Mirnov coils, and toroidally distributed coils estimated toroidal mode numbers of n=5-10. Quantitatively similar precursors have been observed in ohmic H-mode plasmas as well, though significantly fewer events are seen in the ohmic cases and none were observed in the near-threshold NBI H-modes studied. Development of Velocimetry and Image Analysis Techniques: Along with the experiments listed above, the Colorado group has continued to explore various velocimetry techniques and their range of validity. We have developed a “linear optical flow” code, which calculates smooth velocity maps while accurately assessing local regions of high curl. This is critical for separating spatial scales of velocity behavior, and thus transport. This code has recently come on-line, and we are currently using it to revisit a number of older datasets. Additionally, we have worked on developing pattern-recognition techniques for imaging diagnostics, based on established digital image compression algorithms. This has the potential to open the analysis of turbulent plasma behavior beyond the well-trodden Fourier and wavelet approaches. Finally, we have extended several of these image-analysis routines to multiple other diagnostic sets, including GPI datasets in NSTX and ECEI imaging on DIII-D. In one study, correlation maps were used to measure the full 2-D mode structure of drift-wave level structures using ECEI for the first time. This enabled direct comparison to gyrokinetic simulations using the GEM code, from which is was determined that TEM modes were being measured in DIII-D.« less

LMSD: LIPID MAPS structure database

PubMed Central

Sud, Manish; Fahy, Eoin; Cotter, Dawn; Brown, Alex; Dennis, Edward A.; Glass, Christopher K.; Merrill, Alfred H.; Murphy, Robert C.; Raetz, Christian R. H.; Russell, David W.; Subramaniam, Shankar

2007-01-01

The LIPID MAPS Structure Database (LMSD) is a relational database encompassing structures and annotations of biologically relevant lipids. Structures of lipids in the database come from four sources: (i) LIPID MAPS Consortium's core laboratories and partners; (ii) lipids identified by LIPID MAPS experiments; (iii) computationally generated structures for appropriate lipid classes; (iv) biologically relevant lipids manually curated from LIPID BANK, LIPIDAT and other public sources. All the lipid structures in LMSD are drawn in a consistent fashion. In addition to a classification-based retrieval of lipids, users can search LMSD using either text-based or structure-based search options. The text-based search implementation supports data retrieval by any combination of these data fields: LIPID MAPS ID, systematic or common name, mass, formula, category, main class, and subclass data fields. The structure-based search, in conjunction with optional data fields, provides the capability to perform a substructure search or exact match for the structure drawn by the user. Search results, in addition to structure and annotations, also include relevant links to external databases. The LMSD is publicly available at PMID:17098933

Plasma impact on structural, morphological and optical properties of copper acetylacetonate thin films.

PubMed

Abdel-Khalek, H; El-Samahi, M I; El-Mahalawy, Ahmed M

2018-06-15

The influence of plasma exposure on structural, morphological and optical properties of copper (II) acetylacetonate thin films deposited by thermal evaporation technique was investigated. Copper (II) acetylacetonate as-grown thin films were exposed to the atmospheric plasma for different times. The exposure of as-grown cu(acac) 2 thin film to atmospheric plasma for 5min modified its structural, morphological and optical properties. The effect of plasma exposure on structure and roughness of cu(acac) 2 thin films was evaluated by XRD and AFM techniques, respectively. The XRD results showed an increment in crystallinity due to exposure for 5min, but, when the exposure time reaches 10min, the film was transformed to an amorphous state. The AFM results revealed a strong modification of films roughness when the average roughness decreased from 63.35nm to ~1nm as a result of interaction with plasma. The optical properties of as-grown and plasma exposured cu(acac) 2 thin films were studied using spectrophotometric method. The exposure of cu(acac) 2 thin films to plasma produced the indirect energy gap decrease from 3.20eV to 2.67eV for 10min exposure time. The dispersion parameters were evaluated in terms of single oscillator model for as-grown and plasma exposured thin films. The influence of plasma exposure on third order optical susceptibility was studied. Copyright © 2018 Elsevier B.V. All rights reserved.

Ionospheric TEC Weather Map Over South America

NASA Astrophysics Data System (ADS)

Takahashi, H.; Wrasse, C. M.; Denardini, C. M.; Pádua, M. B.; de Paula, E. R.; Costa, S. M. A.; Otsuka, Y.; Shiokawa, K.; Monico, J. F. Galera; Ivo, A.; Sant'Anna, N.

2016-11-01

Ionospheric weather maps using the total electron content (TEC) monitored by ground-based Global Navigation Satellite Systems (GNSS) receivers over South American continent, TECMAP, have been operationally produced by Instituto Nacional de Pesquisas Espaciais's Space Weather Study and Monitoring Program (Estudo e Monitoramento Brasileiro de Clima Especial) since 2013. In order to cover the whole continent, four GNSS receiver networks, (Rede Brasileiro de Monitoramento Contínuo) RBMC/Brazilian Institute for Geography and Statistics, Low-latitude Ionospheric Sensor Network, International GNSS Service, and Red Argentina de Monitoreo Satelital Continuo, in total 140 sites, have been used. TECMAPs with a time resolution of 10 min are produced in 12 h time delay. Spatial resolution of the map is rather low, varying between 50 and 500 km depending on the density of the observation points. Large day-to-day variabilities of the equatorial ionization anomaly have been observed. Spatial gradient of TEC from the anomaly trough (total electron content unit, 1 TECU = 1016 el m-2 (TECU) <10) to the crest region (TECU > 80) causes a large ionospheric range delay in the GNSS positioning system. Ionospheric plasma bubbles, their seeding and development, could be monitored. This plasma density (spatial and temporal) variability causes not only the GNSS-based positioning error but also radio wave scintillations. Monitoring of these phenomena by TEC mapping becomes an important issue for space weather concern for high-technology positioning system and telecommunication.

In situ AFM imaging of apolipoprotein A-I directly derived from plasma HDL.

PubMed

Gan, Chaoye; Wang, Zhexuan; Chen, Yong

2017-04-01

The major apolipoproteins of plasma lipoproteins play vital roles in the structural integrity and physiological functions of lipoproteins. More than ten structural models of apolipoprotein A-I (apoA-I), the major apolipoprotein of high-density lipoprotein (HDL), have been developed successively. In these models, apoA-I was supposed to organize in a ring-shaped form. To date, however, there is no direct evidence under physiological condition. Here, atomic force microscopy (AFM) was used to in situ visualize the organization of apoA-I, which was exposed via depletion of the lipid component of plasma HDL pre-immobilized on functionalized mica sheets. For the first time, the ring-shaped coarse structure and three detailed structures (crescent-shaped, gapped "O"-shaped, and parentheses-shaped structures, respectively) of apoA-I in plasma HDL, which have the ability of binding scavenger receptors, were directly observed and quantitatively measured by AFM. The three detailed structures probably represent the different extents to which the lipid component of HDL was depleted. Data on lipid depletion of HDL may provide clues to understand lipid insertion of HDL. These data provide important information for the understanding of the structure/maturation of plasma HDL. Moreover, they suggest a powerful method for directly visualizing the major apolipoproteins of plasma lipoproteins or the protein component of lipoprotein-like lipid-protein complexes. Copyright © 2017 Elsevier B.V. All rights reserved.

Motion of the plasma critical layer during relativistic-electron laser interaction with immobile and comoving ion plasma for ion accelerationa)

NASA Astrophysics Data System (ADS)

Sahai, Aakash A.

2014-05-01

We analyze the motion of the plasma critical layer by two different processes in the relativistic-electron laser-plasma interaction regime (a0>1). The differences are highlighted when the critical layer ions are stationary in contrast to when they move with it. Controlling the speed of the plasma critical layer in this regime is essential for creating low-β traveling acceleration structures of sufficient laser-excited potential for laser ion accelerators. In Relativistically Induced Transparency Acceleration (RITA) scheme, the heavy plasma-ions are fixed and only trace-density light-ions are accelerated. The relativistic critical layer and the acceleration structure move longitudinally forward by laser inducing transparency through apparent relativistic increase in electron mass. In the Radiation Pressure Acceleration (RPA) scheme, the whole plasma is longitudinally pushed forward under the action of the laser radiation pressure, possible only when plasma ions co-propagate with the laser front. In RPA, the acceleration structure velocity critically depends upon plasma-ion mass in addition to the laser intensity and plasma density. In RITA, mass of the heavy immobile plasma-ions does not affect the speed of the critical layer. Inertia of the bared immobile ions in RITA excites the charge separation potential, whereas RPA is not possible when ions are stationary.

Using concept mapping to evaluate knowledge structure in problem-based learning.

PubMed

Hung, Chia-Hui; Lin, Chen-Yung

2015-11-27

Many educational programs incorporate problem-based learning (PBL) to promote students' learning; however, the knowledge structure developed in PBL remains unclear. The aim of this study was to use concept mapping to generate an understanding of the use of PBL in the development of knowledge structures. Using a quasi-experimental study design, we employed concept mapping to illustrate the effects of PBL by examining the patterns of concepts and differences in the knowledge structures of students taught with and without a PBL approach. Fifty-two occupational therapy undergraduates were involved in the study and were randomly divided into PBL and control groups. The PBL group was given two case scenarios for small group discussion, while the control group continued with ordinary teaching and learning. Students were asked to make concept maps after being taught about knowledge structure. A descriptive analysis of the morphology of concept maps was conducted in order to compare the integration of the students' knowledge structures, and statistical analyses were done to understand the differences between groups. Three categories of concept maps were identified as follows: isolated, departmental, and integrated. The students in the control group constructed more isolated maps, while the students in the PBL group tended toward integrated mapping. Concept Relationships, Hierarchy Levels, and Cross Linkages in the concept maps were significantly greater in the PBL group; however, examples of concept maps did not differ significantly between the two groups. The data indicated that PBL had a strong effect on the acquisition and integration of knowledge. The important properties of PBL, including situational learning, problem spaces, and small group interactions, can help students to acquire more concepts, achieve an integrated knowledge structure, and enhance clinical reasoning.

Global Magnetohydrodynamic Modeling of the Solar Corona

NASA Technical Reports Server (NTRS)

Linker, Jon A.

1998-01-01

The coronal magnetic field defines the structure of the solar corona, the position of the heliospheric current sheet, the regions of fast and slow solar wind, and the most likely sites of coronal mass ejections. There are few measurements of the magnetic fields in the corona, but the line-of-sight component of the global magnetic fields in the photosphere have been routinely measured for many years (for example, at Stanford's Wilcox Solar Observatory, and at the National Solar Observatory at Kitt Peak). The SOI/MDI instrument is now providing high-resolution full-disk magnetograms several times a day. Understanding the large-scale structure of the solar corona and inner heliosphere requires accurately mapping the measured photospheric magnetic field into the corona and outward. Ideally, a model should not only extrapolate the magnetic field, but should self-consistently reconstruct both the plasma and magnetic fields in the corona and solar wind. Support from our NASA SR&T contract has allowed us to develop three-dimensional magnetohydrodynamic (MHD) computations of the solar corona that incorporate observed photospheric magnetic fields into the boundary conditions. These calculations not only describe the magnetic field in the corona and interplanetary spice, but also predict the plasma properties as well. Our computations thus far have been successful in reproducing many aspects of both coronal and interplanetary data, including the structure of the streamer belt, the location of coronal hole boundaries, and the position and shape of the heliospheric current sheet. The most widely used technique for extrapolating the photospheric magnetic field into the corona and heliosphere are potential field models, such as the potential field source-surface model (PFSS),and the potential field current-sheet (PFCS) model

The Near-Earth Plasma Environment

NASA Technical Reports Server (NTRS)

Pfaff, Robert F., Jr.

2012-01-01

An overview of the plasma environment near the earth is provided. We describe how the near-earth plasma is formed, including photo-ionization from solar photons and impact ionization at high latitudes from energetic particles. We review the fundamental characteristics of the earth's plasma environment, with emphasis on the ionosphere and its interactions with the extended neutral atmosphere. Important processes that control ionospheric physics at low, middle, and high latitudes are discussed. The general dynamics and morphology of the ionized gas at mid- and low-latitudes are described including electrodynamic contributions from wind-driven dynamos, tides, and planetary-scale waves. The unique properties of the near-earth plasma and its associated currents at high latitudes are shown to depend on precipitating auroral charged particles and strong electric fields which map earthward from the magnetosphere. The upper atmosphere is shown to have profound effects on the transfer of energy and momentum between the high-latitude plasma and the neutral constituents. The article concludes with a discussion of how the near-earth plasma responds to magnetic storms associated with solar disturbances.

Time resolved interferometric study of the plasma plume induced shock wave in confined geometry: Two-dimensional mapping of the ambient and plasma density

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

Choudhury, Kaushik; Singh, R. K.; Kumar, Ajai, E-mail: ajai@ipr.res.in

2016-04-15

An experimental investigation of the laser produced plasma induced shock wave in the presence of confining walls placed along the axial as well as the lateral direction has been performed. A time resolved Mach Zehnder interferometer is set up to track the primary as well as the reflected shock waves and its effect on the evolving plasma plume has been studied. An attempt has been made to discriminate the electronic and medium density contributions towards the changes in the refractive index of the medium. Two dimensional spatial distributions for both ambient medium density and plasma density (electron density) have beenmore » obtained by employing customised inversion technique and algorithm on the recorded interferograms. The observed density pattern of the surrounding medium in the presence of confining walls is correlated with the reflected shock wave propagation in the medium. Further, the shock wave plasma interaction and the subsequent changes in the shape and density of the plasma plume in confined geometry are briefly described.« less

Structure and structure-preserving algorithms for plasma physics

NASA Astrophysics Data System (ADS)

Morrison, P. J.

2016-10-01

Conventional simulation studies of plasma physics are based on numerically solving the underpinning differential (or integro-differential) equations. Usual algorithms in general do not preserve known geometric structure of the physical systems, such as the local energy-momentum conservation law, Casimir invariants, and the symplectic structure (Poincaré invariants). As a consequence, numerical errors may accumulate coherently with time and long-term simulation results may be unreliable. Recently, a series of geometric algorithms that preserve the geometric structures resulting from the Hamiltonian and action principle (HAP) form of theoretical models in plasma physics have been developed by several authors. The superiority of these geometric algorithms has been demonstrated with many test cases. For example, symplectic integrators for guiding-center dynamics have been constructed to preserve the noncanonical symplectic structures and bound the energy-momentum errors for all simulation time-steps; variational and symplectic algorithms have been discovered and successfully applied to the Vlasov-Maxwell system, MHD, and other magnetofluid equations as well. Hamiltonian truncations of the full Vlasov-Maxwell system have opened the field of discrete gyrokinetics and led to the GEMPIC algorithm. The vision that future numerical capabilities in plasma physics should be based on structure-preserving geometric algorithms will be presented. It will be argued that the geometric consequences of HAP form and resulting geometric algorithms suitable for plasma physics studies cannot be adapted from existing mathematical literature but, rather, need to be discovered and worked out by theoretical plasma physicists. The talk will review existing HAP structures of plasma physics for a variety of models, and how they have been adapted for numerical implementation. Supported by DOE DE-FG02-04ER-54742.

a Case Study of Plasma Blob Associated with Plasma Bubble in Low Latitude Region in the Brazilian Sector Using All-Sky Images and DMSP Satellite

NASA Astrophysics Data System (ADS)

Tardelli, F. C.; Abalde, J. R.; Pimenta, A. A.; Kavutarapu, V.; Tardelli, A.

2016-12-01

Using optical techniques and satellite data a plasma blob case was observed on February 23, 2007, in São José dos Campos (SJC) (23.21°S, 45.86°O; dip. Lat. 17.6°S) in the Brazilian sector. This is the first observation of plasma blob in SJC region using data from optical techniques and satellite measurements. The plasma blob is the enhancements in plasma density by a factor of 2 or more above background plasma. Simultaneous all-sky images were used to map the spatial extent of plasma blob. DMSP satellite data were used to confirm the enhancements in plasma density in the ionosphere, which provides important parameters of the ionospheric behavior during the event. During the night of present study, the plasma blob was associated with a plasma bubble and the average zonal drift velocities are 61±6 m-s and 74±8 m-s, respectively. The average North/South and East/West extension of the blob were 591 km and 328 km, respectively. Furthermore, the average longitudinal drift velocity was 85±13 m-s. In this work plasma density is found to be enhanced by a factor of 2 compared to the background plasma. We report for the first time plasma blob in SJC at low latitude region associated with plasma bubble and present important features of their behavior.

Computation of statistical secondary structure of nucleic acids.

PubMed Central

Yamamoto, K; Kitamura, Y; Yoshikura, H

1984-01-01

This paper presents a computer analysis of statistical secondary structure of nucleic acids. For a given single stranded nucleic acid, we generated "structure map" which included all the annealing structures in the sequence. The map was transformed into "energy map" by rough approximation; here, the energy level of every pairing structure consisting of more than 2 successive nucleic acid pairs was calculated. By using the "energy map", the probability of occurrence of each annealed structure was computed, i.e., the structure was computed statistically. The basis of computation was the 8-queen problem in the chess game. The validity of our computer programme was checked by computing tRNA structure which has been well established. Successful application of this programme to small nuclear RNAs of various origins is demonstrated. PMID:6198622

The Canadian Hydrogen Intensity Mapping Experiment (CHIME)

NASA Astrophysics Data System (ADS)

Vanderlinde, Keith; Chime Collaboration

2014-04-01

Hydrogen Intensity (HI) mapping uses redshifted 21cm emission from neutral hydrogen as a 3D tracer of Large Scale Structure (LSS) in the Universe. Imprinted in the LSS is a remnant of the acoustic waves which propagated through the primordial plasma. This feature, the Baryon Acoustic Oscillation (BAO), has a characteristic scale of ~150 co-moving Mpc, which appears in the spatial correlation of LSS. By charting the evolution of this scale over cosmic time, we trace the expansion history of the Universe, constraining the Dark Energy equation of state as it becomes a significant component, particularly at redshifts poorly probed by current BAO surveys. In this talk I will introduce CHIME, a transit radio interferometer designed specifically for this purpose. CHIME is an ambitious new telescope, being built in British Columbia, Canada, and composed of five 20m x 100m parabolic reflectors which focus radiation in one direction (east-west) while interferometry is used to resolve beams in the other (north-south). Earth rotation sweeps them across the sky, resulting in complete daily coverage of the northern celestial hemisphere. Commissioning is underway on the 40 x 37m "Pathfinder" telescope, and the full sized 100m x 100m instrument is funded and under development.

The Structure-Mapping Engine: Algorithm and Examples.

ERIC Educational Resources Information Center

Falkenhainer, Brian; And Others

This description of the Structure-Mapping Engine (SME), a flexible, cognitive simulation program for studying analogical processing which is based on Gentner's Structure-Mapping theory of analogy, points out that the SME provides a "tool kit" for constructing matching algorithms consistent with this theory. This report provides: (1) a…

Analysis of band structure, transmission properties, and dispersion behavior of THz wave in one-dimensional parabolic plasma photonic crystal

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

Askari, Nasim; Eslami, Esmaeil, E-mail: eeslami@iust.ac.ir; Mirzaie, Reza

2015-11-15

The photonic band gap of obliquely incident terahertz electromagnetic waves in a one-dimensional plasma photonic crystal is studied. The periodic structure consists of lossless dielectric and inhomogeneous plasma with a parabolic density profile. The dispersion relation and the THz wave transmittance are analyzed based on the electromagnetic equations and transfer matrix method. The dependence of effective plasma frequency and photonic band gap characteristics on dielectric and plasma thickness, plasma density, and incident angle are discussed in detail. A theoretical calculation for effective plasma frequency is presented and compared with numerical results. Results of these two methods are in good agreement.

The Mesoscale Ionospheric Simulation Testbed (MIST) Regional Data Assimilation Model (Invited)

NASA Astrophysics Data System (ADS)

Comberiate, J.; Kelly, M. A.; Miller, E.; Paxton, L.

2013-12-01

The Mesoscale Ionospheric Simulation Testbed (MIST) provides a regional nowcast and forecast of electron density values and has sufficient resolution to include equatorial plasma bubbles. The SSUSI instrument on the DMSP F18 satellite has high-resolution nightly observations of plasma bubbles at 8 PM local time throughout the current solar maximum. MIST can assimilate SSUSI UV observations, GPS TEC measurements, and SCINDA S4 readings simultaneously into a single scintillation map over a region of interest. MIST also models ionospheric physics to provide a short-term UHF scintillation forecast based on assimilated data. We will present examples of electron density and scintillation maps from MIST. We will also discuss the potential to predict scintillation occurrence up to 6 hours in advance using observations of the equatorial arcs from SSUSI observations at 5:30 PM local time on the DMSP F17 satellite.

Optimizing Compliance and Thermal Conductivity of Plasma Sprayed Thermal Barrier Coatings via Controlled Powders and Processing Strategies

NASA Astrophysics Data System (ADS)

Tan, Yang; Srinivasan, Vasudevan; Nakamura, Toshio; Sampath, Sanjay; Bertrand, Pierre; Bertrand, Ghislaine

2012-09-01

The properties and performance of plasma-sprayed thermal barrier coatings (TBCs) are strongly dependent on the microstructural defects, which are affected by starting powder morphology and processing conditions. Of particular interest is the use of hollow powders which not only allow for efficient melting of zirconia ceramics but also produce lower conductivity and more compliant coatings. Typical industrial hollow spray powders have an assortment of densities resulting in masking potential advantages of the hollow morphology. In this study, we have conducted process mapping strategies using a novel uniform shell thickness hollow powder to control the defect microstructure and properties. Correlations among coating properties, microstructure, and processing reveal feasibility to produce highly compliant and low conductivity TBC through a combination of optimized feedstock and processing conditions. The results are presented through the framework of process maps establishing correlations among process, microstructure, and properties and providing opportunities for optimization of TBCs.

Full-Sun observations for identifying the source of the slow solar wind

PubMed Central

Brooks, David H.; Ugarte-Urra, Ignacio; Warren, Harry P.

2015-01-01

Fast (>700 km s−1) and slow (~400 km s−1) winds stream from the Sun, permeate the heliosphere and influence the near-Earth environment. While the fast wind is known to emanate primarily from polar coronal holes, the source of the slow wind remains unknown. Here we identify possible sites of origin using a slow solar wind source map of the entire Sun, which we construct from specially designed, full-disk observations from the Hinode satellite, and a magnetic field model. Our map provides a full-Sun observation that combines three key ingredients for identifying the sources: velocity, plasma composition and magnetic topology and shows them as solar wind composition plasma outflowing on open magnetic field lines. The area coverage of the identified sources is large enough that the sum of their mass contributions can explain a significant fraction of the mass loss rate of the solar wind. PMID:25562705

Fine Structure of a Laser-Plasma Filament in Air

NASA Astrophysics Data System (ADS)

Eisenmann, Shmuel; Pukhov, Anatoly; Zigler, Arie

2007-04-01

The ability to select and stabilize a single filament during propagation of an ultrashort high-intensity laser pulse in air makes it possible to examine the longitudinal structure of the plasma channel left in its wake. We present detailed measurements of plasma density variations along laser propagation. Over the length of the filament, electron density variations of 3 orders of magnitude are measured. They display evidence of a meter-long postionization range, along which a self-guided structure is observed coupled with a low plasma density, corresponding to ˜3 orders of magnitude decrease from the peak density level.

High-resolution characterization of sequence signatures due to non-random cleavage of cell-free DNA.

PubMed

Chandrananda, Dineika; Thorne, Natalie P; Bahlo, Melanie

2015-06-17

High-throughput sequencing of cell-free DNA fragments found in human plasma has been used to non-invasively detect fetal aneuploidy, monitor organ transplants and investigate tumor DNA. However, many biological properties of this extracellular genetic material remain unknown. Research that further characterizes circulating DNA could substantially increase its diagnostic value by allowing the application of more sophisticated bioinformatics tools that lead to an improved signal to noise ratio in the sequencing data. In this study, we investigate various features of cell-free DNA in plasma using deep-sequencing data from two pregnant women (>70X, >50X) and compare them with matched cellular DNA. We utilize a descriptive approach to examine how the biological cleavage of cell-free DNA affects different sequence signatures such as fragment lengths, sequence motifs at fragment ends and the distribution of cleavage sites along the genome. We show that the size distributions of these cell-free DNA molecules are dependent on their autosomal and mitochondrial origin as well as the genomic location within chromosomes. DNA mapping to particular microsatellites and alpha repeat elements display unique size signatures. We show how cell-free fragments occur in clusters along the genome, localizing to nucleosomal arrays and are preferentially cleaved at linker regions by correlating the mapping locations of these fragments with ENCODE annotation of chromatin organization. Our work further demonstrates that cell-free autosomal DNA cleavage is sequence dependent. The region spanning up to 10 positions on either side of the DNA cleavage site show a consistent pattern of preference for specific nucleotides. This sequence motif is present in cleavage sites localized to nucleosomal cores and linker regions but is absent in nucleosome-free mitochondrial DNA. These background signals in cell-free DNA sequencing data stem from the non-random biological cleavage of these fragments. This sequence structure can be harnessed to improve bioinformatics algorithms, in particular for CNV and structural variant detection. Descriptive measures for cell-free DNA features developed here could also be used in biomarker analysis to monitor the changes that occur during different pathological conditions.

Continuous blood densitometry - Fluid shifts after graded hemorrhage in animals

NASA Technical Reports Server (NTRS)

Hinghofer-Szalkay, H.

1986-01-01

Rapid fluid shifts in four pigs and two dogs subjected to graded hemorrhage are investigated. Arterial blood density (BD), mean arterial pressure (MAP), central venous pressure (CVP), arterial plasma density (PD), hematocrit (Hct) and erythrocyte density were measured. The apparatus and mechancial oscillator technique for measuring density are described. Fluid shifts between red blood cells and blood plasma and alterations in the whole-body-to-large vessel Hct, F(cell) are studied using two models. The bases of the model calculations are discussed. A decrease in MAP, CVP, and BP is detected at the beginning of hemorrhaging; continued bleeding results in further BD decrease correlating with volume displacement. The data reveal that at 15 ml/kg blood loss the mean PD and BD dropped by 0.99 + or - 0.15 and 2.42 + or 0.26 g/liter, respectively, and the Hct dropped by 2.40 + or 0.47 units. The data reveal that inward-shifted fluid has a higher density than normal ultrafiltrate and/or there is a rise in the F(cell) ratio. It is noted that rapid fluid replacement ranged from 5.8 + or - 0.8 to 10.6 + or - 2.0 percent of the initial plasma volume.

Structuring in complex plasma for nonlinearly screened dust particles

NASA Astrophysics Data System (ADS)

Tsytovich, Vadim; Gusein-zade, Namik

2014-03-01

An explanation is proposed for the recently discovered effect of spontaneous dusty plasma structuring (and the appearance of compact dust structures) under conditions of nonlinear dust screening. Physical processes are considered that make homogenous dusty plasma universally unstable and lead to the appearance of structures. It is shown for the first time that the efficiency of structuring increases substantially in the presence of plasma flows caused by the charging of nonlinearly screened dust grains. General results are obtained for arbitrary nonlinear screening, and special attention is paid to the model of nonlinear screening often used since 1964. The growth rate of structuring instability is derived. It is shown that, in the case of nonlinear screening, the structuring has a threshold determined by the friction of grains against the neutral gas. The theoretically obtained threshold agrees with recent experimental observations. The dispersion relation for dusty plasma structuring is shown to be similar to the dispersion relation for gravitational instability with an effective gravitational constant. The effective dust attraction caused by this instability is shown to be collective, and the dependence of the effective gravitational constant on the dust-to-ion density ratio is found explicitly for the first time. It is demonstrated that the proposed method of calculation of dust attraction by using the effective gravitational constant is the most efficient and straightforward. Understanding of the role of nonlinear screening gives deeper physical grounds for the theoretical interpretation of the observed phenomenon of dust crystal formation in complex plasmas.

Mapping forest structure, species gradients and growth in an urban area using lidar and hyperspectral imagery

NASA Astrophysics Data System (ADS)

Gu, Huan

Urban forests play an important role in the urban ecosystem by providing a range of ecosystem services. Characterization of forest structure, species variation and growth in urban forests is critical for understanding the status, function and process of urban ecosystems, and helping maximize the benefits of urban ecosystems through management. The development of methods and applications to quantify urban forests using remote sensing data has lagged the study of natural forests due to the heterogeneity and complexity of urban ecosystems. In this dissertation, I quantify and map forest structure, species gradients and forest growth in an urban area using discrete-return lidar, airborne imaging spectroscopy and thermal infrared data. Specific objectives are: (1) to demonstrate the utility of leaf-off lidar originally collected for topographic mapping to characterize and map forest structure and associated uncertainties, including aboveground biomass, basal area, diameter, height and crown size; (2) to map species gradients using forest structural variables estimated from lidar and foliar functional traits, vegetation indices derived from AVIRIS hyperspectral imagery in conjunction with field-measured species data; and (3) to identify factors related to relative growth rates in aboveground biomass in the urban forests, and assess forest growth patterns across areas with varying degree of human interactions. The findings from this dissertation are: (1) leaf-off lidar originally acquired for topographic mapping provides a robust, potentially low-cost approach to quantify spatial patterns of forest structure and carbon stock in urban areas; (2) foliar functional traits and vegetation indices from hyperspectral data capture gradients of species distributions in the heterogeneous urban landscape; (3) species gradients, stand structure, foliar functional traits and temperature are strongly related to forest growth in the urban forests; and (4) high uncertainties in our ability to map forest structure, species gradient and growth rate occur in residential neighborhoods and along forest edges. Maps generated from this dissertation provide estimates of broad-scale spatial variations in forest structure, species distributions and growth to the city forest managers. The associated maps of uncertainty help managers understand the limitations of the maps and identify locations where the maps are more reliable and where more data are needed.

ISS and Space Environment Interactions in Event of Plasma Contactor Failure

NASA Technical Reports Server (NTRS)

Carruth, M. R., Jr.; Munafo, Paul M. (Technical Monitor)

2000-01-01

The International Space Station (ISS), illustrated in Figure 1, will be the largest, highest power spacecraft placed in orbit. Because of this the design of the electrical power system diverged markedly from previous systems. The solar arrays will operate at 160 V and the power distribution voltage will be 120 V. The structure is grounded to the negative side of the solar arrays so under the right circumstances it is possible to drive the ISS potential very negative. A plasma contactor has been added to the ISS to provide control of the ISS structure potential relative to the ambient plasma. The ISS requirement is that the ISS structure not be greater than 40 V positive or negative of local plasma. What are the ramifications of operating large structures with such high voltage power systems? The application of a plasma contactor on ISS controls the potential between the structure and the local plasma, preventing degrading effects. It is conceivable that there can be situations where the plasma contactor might be non-functional. This might be due to lack of power, the need to turn it off during some of the build-up sequences, the loss of functionality for both plasma contactors before a replacement can be installed, and similar circumstances. A study was undertaken to understand how important it is to have the contactor functioning and how long it might be off before unacceptable degradation to ISS could occur.

Protein Kinase Mitogen-activated Protein Kinase Kinase Kinase Kinase 4 (MAP4K4) Promotes Obesity-induced Hyperinsulinemia.

PubMed

Roth Flach, Rachel J; Danai, Laura V; DiStefano, Marina T; Kelly, Mark; Menendez, Lorena Garcia; Jurczyk, Agata; Sharma, Rohit B; Jung, Dae Young; Kim, Jong Hun; Kim, Jason K; Bortell, Rita; Alonso, Laura C; Czech, Michael P

2016-07-29

Previous studies revealed a paradox whereby mitogen-activated protein kinase kinase kinase kinase 4 (Map4k4) acted as a negative regulator of insulin sensitivity in chronically obese mice, yet systemic deletion of Map4k4 did not improve glucose tolerance. Here, we report markedly reduced glucose-responsive plasma insulin and C-peptide levels in whole body Map4k4-depleted mice (M4K4 iKO) as well as an impaired first phase of insulin secretion from islets derived from M4K4 iKO mice ex vivo After long-term high fat diet (HFD), M4K4 iKO mice pancreata also displayed reduced β cell mass, fewer proliferating β cells and reduced islet-specific gene mRNA expression compared with controls, although insulin content was normal. Interestingly, the reduced plasma insulin in M4K4 iKO mice exposed to chronic (16 weeks) HFD was not observed in response to acute HFD challenge or short term treatment with the insulin receptor antagonist S961. Furthermore, the improved insulin sensitivity in obese M4K4 iKO mice was abrogated by high exogenous insulin over the course of a euglycemic clamp study, indicating that hypoinsulinemia promotes insulin sensitivity in chronically obese M4K4 iKO mice. These results demonstrate that protein kinase Map4k4 drives obesity-induced hyperinsulinemia and insulin resistance in part by promoting insulin secretion from β cells in mice. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

β-Microseminoprotein Endows Post Coital Seminal Plasma with Potent Candidacidal Activity by a Calcium- and pH-Dependent Mechanism

PubMed Central

Edström Hägerwall, Anneli M. L.; Rydengård, Victoria; Fernlund, Per; Mörgelin, Matthias; Baumgarten, Maria; Cole, Alexander M.; Malmsten, Martin; Kragelund, Birthe B.; Sørensen, Ole E.

2012-01-01

The innate immune factors controlling Candida albicans are mostly unknown. Vulvovaginal candidiasis is common in women and affects approximately 70–75% of all women at least once. Despite the propensity of Candida to colonize the vagina, transmission of Candida albicans following sexual intercourse is very rare. This prompted us to investigate whether the post coital vaginal milieu contained factors active against C. albicans. By CFU assays, we found prominent candidacidal activity of post coital seminal plasma at both neutral and the acid vaginal pH. In contrast, normal seminal plasma did not display candidacidal activity prior to acidification. By antifungal gel overlay assay, one clearing zone corresponding to a protein band was found in both post coital and normal seminal plasma, which was subsequently identified as β-microseminoprotein. At neutral pH, the fungicidal activity of β-microseminoprotein and seminal plasma was inhibited by calcium. By NMR spectroscopy, amino acid residue E71 was shown to be critical for the calcium coordination. The acidic vaginal milieu unleashed the fungicidal activity by decreasing the inhibitory effect of calcium. The candidacidal activity of β-microseminoprotein was mapped to a fragment of the C-terminal domain with no structural similarity to other known proteins. A homologous fragment from porcine β-microseminoprotein demonstrated calcium-dependent fungicidal activity in a CFU assay, suggesting this may be a common feature for members of the β-microseminoprotein family. By electron microscopy, β-microseminoprotein was found to cause lysis of Candida. Liposome experiments demonstrated that β-microseminoprotein was active towards ergosterol-containing liposomes that mimic fungal membranes, offering an explanation for the selectivity against fungi. These data identify β-microseminoprotein as an important innate immune factor active against C. albicans and may help explain the low sexual transmission rate of Candida. PMID:22496651

Application of a XMM-Newton EPIC Monte Carlo to Analysis And Interpretation of Data for Abell 1689, RXJ0658-55 And the Centaurus Clusters of Galaxies

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

Andersson, Karl E.; /Stockholm U. /SLAC; Peterson, J.R.

2007-04-17

We propose a new Monte Carlo method to study extended X-ray sources with the European Photon Imaging Camera (EPIC) aboard XMM Newton. The Smoothed Particle Inference (SPI) technique, described in a companion paper, is applied here to the EPIC data for the clusters of galaxies Abell 1689, Centaurus and RXJ 0658-55 (the ''bullet cluster''). We aim to show the advantages of this method of simultaneous spectral-spatial modeling over traditional X-ray spectral analysis. In Abell 1689 we confirm our earlier findings about structure in temperature distribution and produce a high resolution temperature map. We also confirm our findings about velocity structuremore » within the gas. In the bullet cluster, RXJ 0658-55, we produce the highest resolution temperature map ever to be published of this cluster allowing us to trace what looks like the motion of the bullet in the cluster. We even detect a south to north temperature gradient within the bullet itself. In the Centaurus cluster we detect, by dividing up the luminosity of the cluster in bands of gas temperatures, a striking feature to the north-east of the cluster core. We hypothesize that this feature is caused by a subcluster left over from a substantial merger that slightly displaced the core. We conclude that our method is very powerful in determining the spatial distributions of plasma temperatures and very useful for systematic studies in cluster structure.« less

Spatiotemporal mapping of diffusion dynamics and organization in plasma membranes

NASA Astrophysics Data System (ADS)

Bag, Nirmalya; Ng, Xue Wen; Sankaran, Jagadish; Wohland, Thorsten

2016-09-01

Imaging fluorescence correlation spectroscopy (FCS) and the related FCS diffusion law have been applied in recent years to investigate the diffusion modes of lipids and proteins in membranes. These efforts have provided new insights into the membrane structure below the optical diffraction limit, new information on the existence of lipid domains, and on the influence of the cytoskeleton on membrane dynamics. However, there has been no systematic study to evaluate how domain size, domain density, and the probe partition coefficient affect the resulting imaging FCS diffusion law parameters. Here, we characterize the effects of these factors on the FCS diffusion law through simulations and experiments on lipid bilayers and live cells. By segmenting images into smaller 7  ×  7 pixel areas, we can evaluate the FCS diffusion law on areas smaller than 2 µm and thus provide detailed maps of information on the membrane structure and heterogeneity at this length scale. We support and extend this analysis by deriving a mathematical expression to calculate the mean squared displacement (MSDACF) from the autocorrelation function of imaging FCS, and demonstrate that the MSDACF plots depend on the existence of nanoscopic domains. Based on the results, we derive limits for the detection of domains depending on their size, density, and relative viscosity in comparison to the surroundings. Finally, we apply these measurements to bilayers and live cells using imaging total internal reflection FCS and single plane illumination microscopy FCS.

Plasma-driven ultrashort bunch diagnostics

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

Dornmair, I.; Schroeder, C. B.; Floettmann, K.

2016-06-10

Ultrashort electron bunches are crucial for an increasing number of applications, however, diagnosing their longitudinal phase space remains a challenge. We propose a new method that harnesses the strong electric fields present in a laser driven plasma wakefield. By transversely displacing driver laser and witness bunch, a streaking field is applied to the bunch. This field maps the time information to a transverse momentum change and, consequently, to a change of transverse position. We illustrate our method with simulations where we achieve a time resolution in the attosecond range.

Ion Trapping with Fast-Response Ion-Selective Microelectrodes Enhances Detection of Extracellular Ion Channel Gradients

PubMed Central

Messerli, Mark A.; Collis, Leon P.; Smith, Peter J.S.

2009-01-01

Previously, functional mapping of channels has been achieved by measuring the passage of net charge and of specific ions with electrophysiological and intracellular fluorescence imaging techniques. However, functional mapping of ion channels using extracellular ion-selective microelectrodes has distinct advantages over the former methods. We have developed this method through measurement of extracellular K+ gradients caused by efflux through Ca2+-activated K+ channels expressed in Chinese hamster ovary cells. We report that electrodes constructed with short columns of a mechanically stable K+-selective liquid membrane respond quickly and measure changes in local [K+] consistent with a diffusion model. When used in close proximity to the plasma membrane (<4 μm), the ISMs pose a barrier to simple diffusion, creating an ion trap. The ion trap amplifies the local change in [K+] without dramatically changing the rise or fall time of the [K+] profile. Measurement of extracellular K+ gradients from activated rSlo channels shows that rapid events, 10–55 ms, can be characterized. This method provides a noninvasive means for functional mapping of channel location and density as well as for characterizing the properties of ion channels in the plasma membrane. PMID:19217875

Influences of prostanoids and nitric oxide on post-suspension hypotension in female Sprague-Dawley rats

NASA Technical Reports Server (NTRS)

Eatman, D.; Listhrop, R. A.; Beasley, A. S.; Socci, R. R.; Abukhalaf, I.; Bayorh, M. A.

2003-01-01

Impairment in cardiovascular functions sometimes manifested in astronauts during standing postflight, may be related to the diminished autonomic function and/or excessive production of endothelium-dependent relaxing factors. In the present study, using the 30 degrees head-down tilt (HDT) model, we compared the cardiovascular and biochemical effects of 7 days of suspension and a subsequent 6-h post-suspension period between suspended and non-suspended conscious female Sprague-Dawley rats. Mean arterial pressure (MAP) and heart rate were measured prior to suspension (basal), daily thereafter, and every 2h post-suspension. Following 7 days of suspension, MAP was not different from their basal values, however, upon release from suspension, MAP was significantly reduced compared to the non-suspended rats. Nitric oxide levels were elevated while thromboxane A(2) levels declined significantly in both plasma and tissue samples following post-suspension. The levels of prostacyclin following post-suspension remained unaltered in plasma and aortic rings but was significantly elevated in carotid arterial rings. Therefore, the post-suspension reduction in mean arterial pressure is due mostly to overproduction of nitric oxide and to a lesser extent prostacyclin.

HSP60, oxidative stress parameters and cardiometabolic risk markers in hypertensive and normotensive Slovak females.

PubMed

Kuka, P; Bucova, M; Penz, P; Paulovicova, E; Blazicek, P; Atalay, M; Lietava, J

2010-01-01

The aim of our study was to analyse the relationships between hypertension, HSP60, oxidative stress, lipid profile and cardiometabolic risk in 126 females with arterial hypertension (AHW) and 39 normotensive females (AH-). Females with AH+ were significantly older and more frequently suffered from ischemic heart disease, angina pectoris, prior MI, abdominal obesity, obesity, metabolic syndrome and diabetes mellitus. On the other hand, normotensive females smoked significantly more often. Plasma levels of HSP60 were similar in both AH+ and AH- groups. However, hypertensive females exhibited almost two times lower values of oxidative glutation and lower levels of carbonyl protein, but significantly higher levels of homocysteine. In normotensive females, the total glutathione was the only parameter predicting females with the plasma level of HSP60 = 60 ng/ml. The independent predictors in hypertensive females were angina pectoris, triglycerides and the mean arterial pressure (MAP). MAP had also a borderline significance in normotensive females suggesting an association between HSP60 and blood pressure. MAP formed a J shaped curve with HSP60. Results suggest the association of blood pressure and heart shock protein 60 Kda in form of the J curve (Tab. 11, Fig. 3, Ref. 29).

A plasma source driven predator-prey like mechanism as a potential cause of spiraling intermittencies in linear plasma devices

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

Reiser, D.; Ohno, N.; Tanaka, H.

2014-03-15

Three-dimensional global drift fluid simulations are carried out to analyze coherent plasma structures appearing in the NAGDIS-II linear device (nagoya divertor plasma Simulator-II). The numerical simulations reproduce several features of the intermittent spiraling structures observed, for instance, statistical properties, rotation frequency, and the frequency of plasma expulsion. The detailed inspection of the three-dimensional plasma dynamics allows to identify the key mechanism behind the formation of these intermittent events. The resistive coupling between electron pressure and parallel electric field in the plasma source region gives rise to a quasilinear predator-prey like dynamics where the axisymmetric mode represents the prey and themore » spiraling structure with low azimuthal mode number represents the predator. This interpretation is confirmed by a reduced one-dimensional quasilinear model derived on the basis of the findings in the full three-dimensional simulations. The dominant dynamics reveals certain similarities to the classical Lotka-Volterra cycle.« less

Surface modification and stability of detonation nanodiamonds in microwave gas discharge plasma

NASA Astrophysics Data System (ADS)

Stanishevsky, Andrei V.; Walock, Michael J.; Catledge, Shane A.

2015-12-01

Detonation nanodiamonds (DND), with low hydrogen content, were exposed to microwave plasma generated in pure H2, N2, and O2 gases and their mixtures, and investigated using X-ray diffraction (XRD), Fourier Transform Infrared (FTIR), Raman, and X-ray photoelectron spectroscopies. Considerable alteration of the DND surface was observed under the plasma conditions for all used gases, but the diamond structure of the DND particle core was preserved in most cases. The stabilizing effect of H2 in H2/N2 and H2/O2 binary gas plasmas on the DND structure and the temperature-dependent formation of various CNHx surface groups in N2 and H2/N2 plasmas were observed and discussed for the first time. DND surface oxidation and etching were the main effects of O2 plasma, whereas the N2 plasma led to DND surfaces rich in amide groups below 1073 K and nitrile groups at higher temperatures. Noticeable graphitization of the DND core structure was detected only in N2 plasma when the substrate temperature was above 1103 K.

Single-cycle high-intensity electromagnetic pulse generation in the interaction of a plasma wakefield with regular nonlinear structures.

PubMed

Bulanov, S S; Esirkepov, T Zh; Kamenets, F F; Pegoraro, F

2006-03-01

The interaction of regular nonlinear structures (such as subcycle solitons, electron vortices, and wake Langmuir waves) with a strong wake wave in a collisionless plasma can be exploited in order to produce ultrashort electromagnetic pulses. The electromagnetic field of the nonlinear structure is partially reflected by the electron density modulations of the incident wake wave and a single-cycle high-intensity electromagnetic pulse is formed. Due to the Doppler effect the length of this pulse is much shorter than that of the nonlinear structure. This process is illustrated with two-dimensional particle-in-cell simulations. The considered laser-plasma interaction regimes can be achieved in present day experiments and can be used for plasma diagnostics.

Numerical modelling of electromagnetic loads on fusion device structures

NASA Astrophysics Data System (ADS)

Bettini, Paolo; Furno Palumbo, Maurizio; Specogna, Ruben

2014-03-01

In magnetic confinement fusion devices, during abnormal operations (disruptions) the plasma begins to move rapidly towards the vessel wall in a vertical displacement event (VDE), producing plasma current asymmetries, vessel eddy currents and open field line halo currents, each of which can exert potentially damaging forces upon the vessel and in-vessel components. This paper presents a methodology to estimate electromagnetic loads, on three-dimensional conductive structures surrounding the plasma, which arise from the interaction of halo-currents associated to VDEs with a magnetic field of the order of some Tesla needed for plasma confinement. Lorentz forces, calculated by complementary formulations, are used as constraining loads in a linear static structural analysis carried out on a detailed model of the mechanical structures of a representative machine.

Fabrication of controlled hierarchical wrinkle structures on polydimethylsiloxane via one-step C4F8 plasma treatment

NASA Astrophysics Data System (ADS)

Miao, Liming; Cheng, Xiaoliang; Chen, Haotian; Song, Yu; Guo, Hang; Zhang, Jinxin; Chen, Xuexian; Zhang, Haixia

2018-01-01

We report a simple method for fabricating two-dimensional and nested hierarchical wrinkle structures on polydimethylsiloxane surfaces via one-step C4F8 plasma treatment that innovatively combines two approaches to monolayer wrinkle structure fabrication. The wavelengths of the two dimensions of the wrinkle structures can be controlled by plasma treatment (radio frequency (RF) power and plasma treatment time) and stretching (stretching strain and axial stretching), respectively. We also analyze the different interactions between the two dimensions of wrinkle structures with different wavelengths and explain the phenomenon using Fourier waveform superposition. The character of the two dimensions and hierarchy is obvious when the wavelengths of the two wrinkles are different. In surface wetting tests, the hierarchical wrinkle shows great hydrophobicity and keeps the stretching property under 25%.

Sharp plasma pinnacle structure based on shockwave for an improved laser wakefield accelerator

NASA Astrophysics Data System (ADS)

Fang, Ming; Zhang, Zhijun; Wang, Wentao; Liu, Jiansheng; Li, Ruxin

2018-07-01

We created a sharp plasma pinnacle structure for localized electron injection and controlled acceleration in a laser wakefield accelerator. The formation of this shockwave-based pinnacle structure was investigated using aerodynamic theory. Details and scaling laws for the shockwave angle, shock position, shock width, and density ratio were experimentally and theoretically presented. Such work is crucial to yielding an expected plasma density distribution in a laser–plasma experiment but has had little discussion in the literature. Compared with the commonly used shock downramp structure, the particle-in-cell simulations demonstrated that the e beam injected in the created pinnacle structure could be accelerated to higher energy with much smaller root-mean-square relative energy spread. Moreover, this study indicated that the beam charge and transverse emittance can be tuned by the shock angle.

VLF waves in the foreshock

NASA Technical Reports Server (NTRS)

Strangeway, R. J.; Crawford, G. K.

1995-01-01

Plasma waves observed in the VLF range upstream of planetary bow shocks not only modify the particle distributions, but also provide important information about the acceleration processes that occur at the bow shock. Electron plasma oscillations observed near the tangent field line in the electron foreshock are generated by electrons reflected at the bow shock through a process that has been referred to as Fast Fermi acceleration. Fast Fermi acceleration is the same as shock-drift acceleration, which is one of the mechanisms by which ions are energized at the shock. We have generated maps of the VLF emissions upstream of the Venus bow shock, using these maps to infer properties of the shock energization processes. We find that the plasma oscillations extend along the field line up to a distance that appears to be controlled by the shock scale size, implying that shock curvature restricsts the flux and energy of reflected electrons. We also find that the ion acoustic waves are observed in the ion foreshock, but at Venus these emissions are not detected near the ULF forshock boundary. Through analogy with terrestrial ion observations, this implies that the ion acoustic waves are not generated by ion beams, but are instead generated by diffuse ion distributions found deep within the ion foreshock. However, since the shock is much smaller at Venus, and there is no magnetosphere, we might expect ion distributions within the ion foreshock to be different than at the Earth. Mapping studies of the terrestrial foreshock similar to those carried out at Venus appear to be necessary to determine if the inferences drawn from Venus data are applicable to other foreshocks.

Fine structure of modal focusing effect in a three dimensional plasma-sheath-lens formed by disk electrodes

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

Stamate, Eugen, E-mail: eust@dtu.dk; Venture Business Laboratory, Nagoya University, C3-1, Chikusa-ku, Nagoya 464-8603; Yamaguchi, Masahito

2015-08-31

Modal and discrete focusing effects associated with three-dimensional plasma-sheath-lenses show promising potential for applications in ion beam extraction, mass spectrometry, plasma diagnostics and for basic studies of plasma sheath. The ion focusing properties can be adjusted by controlling the geometrical structure of the plasma-sheath-lens and plasma parameters. The positive and negative ion kinetics within the plasma-sheath-lens are investigated both experimentally and theoretically and a modal focusing ring is identified on the surface of disk electrodes. The focusing ring is very sensitive to the sheath thickness and can be used to monitor very small changes in plasma parameters. Three dimensional simulationsmore » are found to be in very good agreement with experiments.« less

Fractal structure of low-temperature plasma of arc discharge as a consequence of the interaction of current sheets

NASA Astrophysics Data System (ADS)

Smolanov, N. A.

2016-01-01

The structure of the particles deposited from the plasma arc discharge were studied. The flow of plasma spreading from the cathode spot to the walls of the vacuum chamber. Electric and magnetic fields to influence the plasma flow. The fractal nature of the particles from the plasma identified by small-angle X-ray scattering. Possible cause of their formation is due to the instability of the growth front and nonequilibrium conditions for their production - a high speed transition of the vapor-liquid-solid or vapor - crystal. The hypothesis of a plasma arc containing dust particles current sheets was proposed.

Semi-automatic mapping of geological Structures using UAV-based photogrammetric data: An image analysis approach

NASA Astrophysics Data System (ADS)

Vasuki, Yathunanthan; Holden, Eun-Jung; Kovesi, Peter; Micklethwaite, Steven

2014-08-01

Recent advances in data acquisition technologies, such as Unmanned Aerial Vehicles (UAVs), have led to a growing interest in capturing high-resolution rock surface images. However, due to the large volumes of data that can be captured in a short flight, efficient analysis of this data brings new challenges, especially the time it takes to digitise maps and extract orientation data. We outline a semi-automated method that allows efficient mapping of geological faults using photogrammetric data of rock surfaces, which was generated from aerial photographs collected by a UAV. Our method harnesses advanced automated image analysis techniques and human data interaction to rapidly map structures and then calculate their dip and dip directions. Geological structures (faults, joints and fractures) are first detected from the primary photographic dataset and the equivalent three dimensional (3D) structures are then identified within a 3D surface model generated by structure from motion (SfM). From this information the location, dip and dip direction of the geological structures are calculated. A structure map generated by our semi-automated method obtained a recall rate of 79.8% when compared against a fault map produced using expert manual digitising and interpretation methods. The semi-automated structure map was produced in 10 min whereas the manual method took approximately 7 h. In addition, the dip and dip direction calculation, using our automated method, shows a mean±standard error of 1.9°±2.2° and 4.4°±2.6° respectively with field measurements. This shows the potential of using our semi-automated method for accurate and efficient mapping of geological structures, particularly from remote, inaccessible or hazardous sites.

A Concept of Cross-Ferroic Plasma Turbulence

PubMed Central

Inagaki, S.; Kobayashi, T.; Kosuga, Y.; Itoh, S.-I.; Mitsuzono, T.; Nagashima, Y.; Arakawa, H.; Yamada, T.; Miwa, Y.; Kasuya, N.; Sasaki, M.; Lesur, M.; Fujisawa, A.; Itoh, K.

2016-01-01

The variety of scalar and vector fields in laboratory and nature plasmas is formed by plasma turbulence. Drift-wave fluctuations, driven by density gradients in magnetized plasmas, are known to relax the density gradient while they can generate flows. On the other hand, the sheared flow in the direction of magnetic fields causes Kelvin-Helmholtz type instabilities, which mix particle and momentum. These different types of fluctuations coexist in laboratory and nature, so that the multiple mechanisms for structural formation exist in extremely non-equilibrium plasmas. Here we report the discovery of a new order in plasma turbulence, in which chained structure formation is realized by cross-interaction between inhomogeneities of scalar and vector fields. The concept of cross-ferroic turbulence is developed, and the causal relation in the multiple mechanisms behind structural formation is identified, by measuring the relaxation rate and dissipation power caused by the complex turbulence-driven flux. PMID:26917218

Theoretical study of the ionospheric plasma cave in the equatorial ionization anomaly region

NASA Astrophysics Data System (ADS)

Chen, Yu-Tsung; Lin, C. H.; Chen, C. H.; Liu, J. Y.; Huba, J. D.; Chang, L. C.; Liu, H.-L.; Lin, J. T.; Rajesh, P. K.

2014-12-01

This paper investigates the physical mechanism of an unusual equatorial electron density structure, plasma cave, located underneath the equatorial ionization anomaly by using theoretical simulations. The simulation results provide important new understanding of the dynamics of the equatorial ionosphere. It has been suggested previously that unusual E>⇀×B>⇀ drifts might be responsible for the observed plasma cave structure, but model simulations in this paper suggest that the more likely cause is latitudinal meridional neutral wind variations. The neutral winds are featured by two divergent wind regions at off-equator latitudes and a convergent wind region around the magnetic equator, resulting in plasma divergences and convergence, respectively, to form the plasma caves structure. The tidal-decomposition analysis further suggests that the cave related meridional neutral winds and the intensity of plasma cave are highly associated with the migrating terdiurnal tidal component of the neutral winds.

Study of the structural and thermal properties of plasma treated jute fibre

NASA Astrophysics Data System (ADS)

Sinha, E.; Rout, S. K.; Barhai, P. K.

2008-08-01

Jute fibres ( Corchorus olitorius), were treated with argon cold plasma for 5, 10 and 15 min. Structural macromolecular parameters of untreated and plasma treated fibres were investigated using small angle X-ray scattering (SAXS), and the crystallinity parameters of the same fibres were determined by using X-ray diffraction (XRD). Differential scanning calorimetry (DSC) was used to study the thermal behavior of the untreated and treated fibres. Comparison and analysis of the results confirmed the changes in the macromolecular structure after plasma treatment. This is due to the swelling of cellulosic particles constituting the fibres, caused by the bombardment of high energetic ions onto the fibre surface. Differential scanning calorimetry data demonstrated the thermal instability of the fibre after cold plasma treatment, as the thermal degradation temperature of hemicelluloses and cellulose was found lowered than that of raw fibre after plasma treatment.

Local Helioseismology of Emerging Active Regions: A Case Study

NASA Astrophysics Data System (ADS)

Kosovichev, Alexander G.; Zhao, Junwei; Ilonidis, Stathis

2018-04-01

Local helioseismology provides a unique opportunity to investigate the subsurface structure and dynamics of active regions and their effect on the large-scale flows and global circulation of the Sun. We use measurements of plasma flows in the upper convection zone, provided by the Time-Distance Helioseismology Pipeline developed for analysis of solar oscillation data obtained by Helioseismic and Magnetic Imager (HMI) on Solar Dynamics Observatory (SDO), to investigate the subsurface dynamics of emerging active region NOAA 11726. The active region emergence was detected in deep layers of the convection zone about 12 hours before the first bipolar magnetic structure appeared on the surface, and 2 days before the emergence of most of the magnetic flux. The speed of emergence determined by tracking the flow divergence with depth is about 1.4 km/s, very close to the emergence speed in the deep layers. As the emerging magnetic flux becomes concentrated in sunspots local converging flows are observed beneath the forming sunspots. These flows are most prominent in the depth range 1-3 Mm, and remain converging after the formation process is completed. On the larger scale converging flows around active region appear as a diversion of the zonal shearing flows towards the active region, accompanied by formation of a large-scale vortex structure. This process occurs when a substantial amount of the magnetic flux emerged on the surface, and the converging flow pattern remains stable during the following evolution of the active region. The Carrington synoptic flow maps show that the large-scale subsurface inflows are typical for active regions. In the deeper layers (10-13 Mm) the flows become diverging, and surprisingly strong beneath some active regions. In addition, the synoptic maps reveal a complex evolving pattern of large-scale flows on the scale much larger than supergranulation

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NOAA Office of Exploration and Research > About OER > Program Review

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Organization Guiding Documents Organizational Structure Map of Staff and Affiliate Locations Strategic Plan Media News Room OER Symposium Overview Organization Guiding Documents Organizational Structure Map of Program Review Home About OER Overview Organization Guiding Documents Organizational Structure Map of

Implementation of structure-mapping inference by event-file binding and action planning: a model of tool-improvisation analogies.

PubMed

Fields, Chris

2011-03-01

Structure-mapping inferences are generally regarded as dependent upon relational concepts that are understood and expressible in language by subjects capable of analogical reasoning. However, tool-improvisation inferences are executed by members of a variety of non-human primate and other species. Tool improvisation requires correctly inferring the motion and force-transfer affordances of an object; hence tool improvisation requires structure mapping driven by relational properties. Observational and experimental evidence can be interpreted to indicate that structure-mapping analogies in tool improvisation are implemented by multi-step manipulation of event files by binding and action-planning mechanisms that act in a language-independent manner. A functional model of language-independent event-file manipulations that implement structure mapping in the tool-improvisation domain is developed. This model provides a mechanism by which motion and force representations commonly employed in tool-improvisation structure mappings may be sufficiently reinforced to be available to inwardly directed attention and hence conceptualization. Predictions and potential experimental tests of this model are outlined.

Development of Broadly Neutralizing Antibodies and Their Mapping by Monomeric gp120 in Human Immunodeficiency Virus Type 1-Infected Humans and Simian-Human Immunodeficiency Virus SHIVSF162P3N-Infected Macaques.

PubMed

Jia, Manxue; Lu, Hong; Markowitz, Martin; Cheng-Mayer, Cecilia; Wu, Xueling

2016-04-01

To improve our understanding of the similarities and differences between neutralizing antibodies elicited by simian-human immunodeficiency virus (SHIV)-infected rhesus macaques and human immunodeficiency virus type 1 (HIV-1)-infected humans, we examined the plasma of 13 viremic macaques infected with SHIVSF162P3Nand 85 HIV-1-infected humans with known times of infection. We identified 5 macaques (38%) from 1 to 2 years postinfection (p.i.) with broadly neutralizing antibodies (bnAbs) against tier 2 HIV-1. In comparison, only 2 out of 42 (5%) human plasma samples collected in a similar time frame of 1 to 3 years p.i. exhibited comparable neutralizing breadths and potencies, with the number increasing to 7 out of 21 (30%) after 3 years p.i. Plasma mapping with monomeric gp120 identified only 2 out of 9 humans and 2 out of 4 macaques that contained gp120-reactive neutralizing antibodies, indicating distinct specificities in these plasma samples, with most of them recognizing the envelope trimer (including gp41) rather than the gp120 monomer. Indeed, a total of 20 gp120-directed monoclonal antibodies (MAbs) isolated from a human subject (AD358) and a Chinese rhesus macaque (GB40) displayed no or limited neutralizing activity against tier 2 strains. These isolated MAbs, mapped to the CD4-binding site, the V3 loop, the inner domain, and the C5 region of gp120, revealed genetic similarity between the human and macaque immunoglobulin genes used to encode some V3-directed MAbs. These results also support the use of envelope trimer probes for efficient isolation of HIV-1 bnAbs. HIV-1 vaccine research can benefit from understanding the development of broadly neutralizing antibodies (bnAbs) in rhesus macaques, commonly used to assess vaccine immunogenicity and efficacy. Here, we examined 85 HIV-1-infected humans and 13 SHIVSF162P3N-infected macaques for bnAbs and found that, similar to HIV-1-infected humans, bnAbs in SHIV-infected macaques are also rare, but their development might have been faster in some of the studied macaques. Plasma mapping with monomeric gp120 indicated that most bnAbs bind to the envelope trimer rather than the gp120 monomer. In support of this, none of the isolated gp120-reactive monoclonal antibodies (MAbs) displayed the neutralization breadth observed in the corresponding plasma. However, the MAb sequences revealed similarity between human and macaque genes used to encode some V3-directed MAbs. Our study sheds light on the timing and development of bnAbs in SHIV-infected macaques in comparison to HIV-1-infected humans and highlights the use of envelope trimer probes for efficient recovery of bnAbs. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

Multi-point observations of large-amplitude electric fields during substorms obtained by THEMIS

NASA Astrophysics Data System (ADS)

Ogasawara, K.; Kasaba, Y.; Nishimura, Y.; Hori, T.; Takada, T.; Miyashita, Y.; Angelopoulos, V.; Bonnell, J. W.; McFadden, J. P.

2009-12-01

Large-amplitude electric fields over 100 mV/m have been observed around the equatorial magnetosphere. These electric fields may contribute to energy transport and particle acceleration in the magnetosphere [e.g., Wygant et al., 2000, 2002], and seem to be related to fast plasma flows with a size of a few Re [Nakamura et al., 2001]. In order to understand their macroscopic characteristics and the effects to magnetic activities, it is important to observe both fields and particles simultaneously at multiple locations within several Re. Five THEMIS probes can frequently provide such chances. In this paper, we show the several events with large-amplitude electric fields during substorms obtained by THEMIS. One of the events is found in 05:50-06:00 UT on 11 March 2008, when TH-D (Xsm=-10.7 Re, Ysm=4.8 Re) and TH-E (Xsm=-10.3 Re, Ysm=5.6 Re) observed intense electric fields. At 05:54 UT, THEMIS GBO-s clearly showed the auroral onset signature. The great intensification was near the SNKQ station, and this structure moved westward with the speed of ~6 km/s. It corresponds to ~200 km/s, as mapped to the TH-D/E location. The footprints of TH-A (Xsm=-6.8 Re, Ysm=-0.4 Re), D, and E were close to the site of the aurora. The location of TH-D was beside that of TH-E, and TH-A was located earthward and eastward from the former two. The enhanced electric fields observed by TH-D and E were associated with magnetic dipolarization and earthward high-speed plasma flow. They were also associated with the depletion of electron density estimated by the spacecraft potential. These features are consistent with the model of plasma bubbles [e.g., Pontius and Wolf, 1990]. The Y components of plasma flows were 200-300 km/s, roughly consistent with the westward auroral motion as mapped to the equatorial magnetosphere. Also, we found that Poynting flux of low frequency was efficient to illuminate the auroral emissions. This fact suggests that electromagnetic energy is transported to the ionosphere. On the other hand, TH-A also observed the large-amplitude electric field greater than TH-D/E. However, TH-A did not detect the high-speed plasma flow nor the depletion of the electron density. In the drift electric field, VxB, estimated from particle and magnetic field observations, TH-D and E detected intense fields, but TH-A found almost zero. This result shows a difference in the role of the electric fields in location of TH-D/E and TH-A. We will show the possible contribution from other factors, such as pressure gradient, current system, and the ionospheric conductivity.

Structure-function analysis of the extracellular domain of the pneumococcal cell division site positioning protein MapZ

NASA Astrophysics Data System (ADS)

Manuse, Sylvie; Jean, Nicolas L.; Guinot, Mégane; Lavergne, Jean-Pierre; Laguri, Cédric; Bougault, Catherine M.; Vannieuwenhze, Michael S.; Grangeasse, Christophe; Simorre, Jean-Pierre

2016-06-01

Accurate placement of the bacterial division site is a prerequisite for the generation of two viable and identical daughter cells. In Streptococcus pneumoniae, the positive regulatory mechanism involving the membrane protein MapZ positions precisely the conserved cell division protein FtsZ at the cell centre. Here we characterize the structure of the extracellular domain of MapZ and show that it displays a bi-modular structure composed of two subdomains separated by a flexible serine-rich linker. We further demonstrate in vivo that the N-terminal subdomain serves as a pedestal for the C-terminal subdomain, which determines the ability of MapZ to mark the division site. The C-terminal subdomain displays a patch of conserved amino acids and we show that this patch defines a structural motif crucial for MapZ function. Altogether, this structure-function analysis of MapZ provides the first molecular characterization of a positive regulatory process of bacterial cell division.

Research on Short Duration Pulsed Radiation Sources.

DTIC Science & Technology

correlate soft X-ray spots with the hard radiation in a 1 kJ plasma focus showed that field structures leading to the appearance of soft X-ray spots...are always present in this plasma focus . These field structures represent m = 0 plasma instabilities and do have a direct influence upon the observed neutron emission. (Author)

Study on the plasma generation characteristics of an induction-triggered coaxial pulsed plasma thruster

NASA Astrophysics Data System (ADS)

Weisheng, CUI; Wenzheng, LIU; Jia, TIAN; Xiuyang, CHEN

2018-02-01

At present, spark plugs are used to trigger discharge in pulsed plasma thrusters (PPT), which are known to be life-limiting components due to plasma corrosion and carbon deposition. A strong electric field could be formed in a cathode triple junction (CTJ) to achieve a trigger function under vacuum conditions. We propose an induction-triggered electrode structure on the basis of the CTJ trigger principle. The induction-triggered electrode structure could increase the electric field strength of the CTJ without changing the voltage between electrodes, contributing to a reduction in the electrode breakdown voltage. Additionally, it can maintain the plasma generation effect when the breakdown voltage is reduced in the discharge experiments. The induction-triggered electrode structure could ensure an effective trigger when the ablation distance of Teflon increases, and the magnetic field produced by the discharge current could further improve the plasma density and propagation velocity. The induction-triggered coaxial PPT we propose has a simplified trigger structure, and it is an effective attempt to optimize the micro-satellite thruster.

Vortex formation in a complex plasma

NASA Astrophysics Data System (ADS)

Ishihara, Osamu

Complex plasma experiments in ground-based laboratories as well as in microgravity conditions have shown the formation of vortex structures in various conditions (e.g., 1,2,3,4). The vortex structures formed in a complex plasma are visible by naked eyes with the help of irradiating laser and the individual dust particles in the structure give us the opportunity to study detailed physics of the commonly observed natural phenomena known such as tornadoes, typhoons, hurricanes and dust devils. Based on the Navier-Stokes equation with proper complex plasma conditions we analyze as much as possible in a universal way the vortex structure and clarifies the role of the controlling parameters like flow velocity and external magnetic field. 1. G. E. Morfill,H. M. Thomas, U. Konopka,H. Rothermel, M. Zuzic, A. Ivlev, and J. Goree, Phys,. Rev. Lett. 83, 1598 (1999). 2. E. Nebbat and R. Annou, Phys. Plasmas 17, 093702 (2010). 3. Y. Saitou and O. Ishihara, Phys. Rev. Lett. 111, 185003 (2013). 4. V. N. Tsytovich and N. G. Gusein-zade, Plasma Phys. Rep. 39, 515 (2013).

Plasma response to the injection of an electron beam

NASA Technical Reports Server (NTRS)

Singh, N.; Schunk, R. W.

1984-01-01

The results of Vlasov-Poisson-solver numerical simulations of the detailed temporal response of a Maxwellian plasma to the sudden injection of an electron beam are presented in graphs and maps and discussed. Phenomena characterized include ion bursts, electron shocks and holes, plasma heating and expulsion, density gradients; cavitons, deep-density-front and solitary-pulse propagation down the density gradient, and Bunemann-mode excitation leading to formation of a virtual cathode and double layers which are at first monotonic or have low-potential-side dips or high-potential-side bumps and become strong as the electron-current density decreases. The strength of the double layer is found to be roughly proportional to the beam energy.

Spatial distribution of the wave field of the surface modes sustaining filamentary discharges

NASA Astrophysics Data System (ADS)

Lishev, St.; Shivarova, A.; Tarnev, Kh.

2008-01-01

The study presents the electrodynamical description of surface-wave-sustained discharges contracted in filamentary structures. The results are for the spatial distribution of the wave field and for the wave propagation characteristics obtained from a two-dimensional model developed for describing surface-wave behavior in plasmas with an arbitrary distribution of the plasma density. In accordance with the experimental observations of filamentary discharges, the plasma density distribution considered is completed by cylindrically shaped gas-discharge channels extended along the discharge length and positioned in the out-of-center region of the discharge, equidistantly in an azimuthal direction. Due to the two-dimensional inhomogeneity of the plasma density of the filamentary structure, the eigen surface mode of the structure is a hybrid wave, with all—six—field components. For identification of its behavior, the surface wave properties in the limiting cases of a plasma ring and a single filament—both radially inhomogeneous—are involved in the discussions. The presentation of the results is for filamentary structures with a decreasing number of filaments (from 10 to 2) starting with the plasma ring, the latter supporting propagation of an azimuthally symmetric wave. Due to the resonance absorption of the surface waves, always present because of the smooth variation of the plasma density, the contours of the critical density are those guiding the surface wave propagation. Decreasing number of filaments in the structure leads to localization of the amplitudes of the wave-field components around the filaments. By analogy with the spatial distribution of the wave field in the plasma ring, the strong resonance enhancement of the wave-field components is along that part of the contour of the critical density which is far off the center of the filamentary structure. The analysis of the spatial distribution of the field components of the filamentary structure shows that the hybrid wave is an eigenmode of the whole structure, i.e., the wave field does not appear as a superposition of fields of eigenmodes of the separated filaments completing it. It is stressed that the spatial distribution of the field components of the eigen hybrid mode of the filamentary structure has an azimuthally symmetric background field.

Does the Loss of Stromal Caveolin-1 Remodel the Tumor Microenvironment by Activating Src-Mediated PEAK1 and PI3K Pathways

DTIC Science & Technology

2016-09-01

Inhibition of MAP kinase pathway prevents plasma protrusions Next we used a selective inhibitor of MAP kinases , PD98059, to address whether we can...from human patients harbor AKT1 and that AKT1 kinase activity is sustained in these particles, nominating them as active signaling platforms...with the extracellular matrix (ECM) and extracellular molecules (2). Though many classic extracellular signaling molecules (e.g., hormones, peptide

Cross-correlation between the 170 GHz survey map and the COBE differential microwave radiometer first-year maps

NASA Technical Reports Server (NTRS)

Ganga, Ken; Cheng, ED; Meyer, Stephan; Page, Lyman

1993-01-01

This letter describes results of a cross-correlation between the 170 GHz partial-sky survey, made with a 3.8 deg beam balloon-borne instrument, and the COBE DMR 'Fit Technique' reduced galaxy all-sky map with a beam of 7 deg. The strong correlation between the data sets implies that the observed structure is consistent with thermal variations in a 2.7 K emitter. A chi-square analysis applied to the correlation function rules out the assumption that there is no structure in either of the two maps. A second test shows that if the DMR map has structure but the 170 GHz map does not, the probability of obtaining the observed correlation is small. Further analyses support the assumption that both maps have structure and that the 170 GHz-DMR cross-correlation is consistent with the analogous DMR correlation function. Maps containing various combinations of noise and Harrison-Zel'dovich power spectra are simulated and correlated to reinforce the result. The correlation provides compelling evidence that both instruments have observed fluctuations consistent with anisotropies in the cosmic microwave background.

Preparation and photocatalytic performance of fibrous Tb3+-doped TiO2 using collagen fiber as template

NASA Astrophysics Data System (ADS)

Luo, Ting; Wan, Xiang-Jun; Jiang, Shang-Xuan; Zhang, Li-Yuan; Hong, Zheng-Qu; Liu, Jiao

2018-04-01

Fibrous Tb3+-doped TiO2 were prepared using collagen fiber as template. Morphology, crystalline structure, surface area, element content, chemical composition and elemental chemical status, microstructure and element distribution of the prepared samples were characterized by using scanning electron microscopy, X-ray diffraction, specific surface area analysis, inductively coupled plasma atomic emission spectrometer, X-ray photoelectron spectroscopy, transmission electron microscope and element mapping, respectively. The photocatalytic activities were evaluated by following degradation of methyl orange. The results showed that the fiber structure of collagen template was fully preserved when the calcination temperature was 500-800 °C. However, with the increase of calcination temperature, crystallinity and average particle size were increased, and the photocatalytic performance was decreased. For 2% Tb3+-TiO2 calcined at 500 °C, the degradation rate of methyl orange reached 93.87% after 6 h when a high-pressure mercury lamp (150 W) was used as the light source for photocatalytic degradation. Titanium tanning agent performance was excellent, the yield of TiO2 was high, and the fiber structure was presented when 0.2 mol/L citric acid/sodium citrate buffer solution was used.

Motion of the plasma critical layer during relativistic-electron laser interaction with immobile and comoving ion plasma for ion acceleration

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

Sahai, Aakash A., E-mail: aakash.sahai@gmail.com

2014-05-15

We analyze the motion of the plasma critical layer by two different processes in the relativistic-electron laser-plasma interaction regime (a{sub 0}>1). The differences are highlighted when the critical layer ions are stationary in contrast to when they move with it. Controlling the speed of the plasma critical layer in this regime is essential for creating low-β traveling acceleration structures of sufficient laser-excited potential for laser ion accelerators. In Relativistically Induced Transparency Acceleration (RITA) scheme, the heavy plasma-ions are fixed and only trace-density light-ions are accelerated. The relativistic critical layer and the acceleration structure move longitudinally forward by laser inducing transparencymore » through apparent relativistic increase in electron mass. In the Radiation Pressure Acceleration (RPA) scheme, the whole plasma is longitudinally pushed forward under the action of the laser radiation pressure, possible only when plasma ions co-propagate with the laser front. In RPA, the acceleration structure velocity critically depends upon plasma-ion mass in addition to the laser intensity and plasma density. In RITA, mass of the heavy immobile plasma-ions does not affect the speed of the critical layer. Inertia of the bared immobile ions in RITA excites the charge separation potential, whereas RPA is not possible when ions are stationary.« less

Paleostress Analysis with Reflection Seismic Data: Example from the Songliao Basin, Northeast China

NASA Astrophysics Data System (ADS)

Liu, G.; Persaud, P.; Zhang, Y.

2017-12-01

Currently paleostress inversion using fault-slip data is a well established approach. However, the deformation history contained in folds has not yet been fully utilized to determine the paleostress field. By applying a 2D FFT-based algorithm to a structure or isopach map derived from reflection seismic data, we find a new way of exploiting the information preserved in folds to determine the paleostress. Our method requires that the strata have a large areal extent and are well preserved. After pre-processing the maps, we find that in the frequency-wavenumber (F-K) domain, folds with similar strikes are grouped into spectrum belts. Each belt parallels the short axis of the fold group and can therefore indicate the direction of the associated maximum horizontal stress. Some information on the relative chronology of stresses can be deduced by comparing the structure and isopach spectrum maps, e.g., if the structure spectrum map has one more spectrum belt than that of the isopach map (an approximate paleo-structure map of the corresponding stratum), we can conclude that the indicated stress postdated the deposition of the stratum. We selected three Late Cretaceous strata from a 3D seismic survey located in the intracontinental Songliao Basin, northeast China. The Songliao has experienced four episodes of deformation: mantle upwelling, rifting, postrift thermal subsidence and structural inversion (Feng et al., 2009). The selected strata were deposited during the third stage. Three structure and two isopach maps were decomposed in the F-K domain. Spectral analysis of the lower isopach map shows eight paleostress directions. We also identify a ninth paleostress in addition to the previous eight from the structure maps and the upper isopach map. The eight stress directions that exist in both the isopach and structure maps may have been active throughout the time period spanned by the strata. We interpret the ninth paleostress as being active after the deposition of the lower stratum. The derived paleostress field fits well with the interpretations of other workers and provides more accurate stress directions and chronology. We further apply this technique to the Central Sichuan basin, southwest China, and confirm the multi-directional compressional tectonics of that basin.

Raman spectroscopic study of plasma-treated salmon DNA

NASA Astrophysics Data System (ADS)

Joon Lee, Geon; Kwon, Young-Wan; Hee Kim, Yong; Ha Choi, Eun

2013-01-01

In this research, we studied the effect of plasma treatment on the optical/structural properties of the deoxyribonucleic acid (DNA) extracted from salmon sperm. DNA-cetyltrimethylammonium (CTMA) films were obtained by complexation of DNA with CTMA. Circular dichroism (CD) and Raman spectra indicated that DNA retained its double helical structure in the solid film. The Raman spectra exhibited several vibration modes corresponding to the nuclear bases and the deoxyribose-phosphate backbones of the DNA, as well as the alkylchains of CTMA. Dielectric-barrier-discharge (DBD) plasma treatment induced structural modification and damage to the DNA, as observed by changes in the ultraviolet-visible absorption, CD, and Raman spectra. The optical emission spectra of the DBD plasma confirmed that DNA modification was induced by plasma ions such as reactive oxygen species and reactive nitrogen species.

Science Measurements for the Io Volcano Observer (IVO)

NASA Astrophysics Data System (ADS)

McEwen, A. S.; Turtle, E. P.; Lorenz, R. D.; Perry, J.; Spencer, J. R.; Kirk, R. L.; Keszthelyi, L. P.; Davies, A. G.; Khurana, K. K.; Jia, X.; Moses, J. I.; Paranicas, C.; Hamilton, C.; Nimmo, F.; Showman, A. P.; Thomas, N.; Wurz, P.; Barabash, S. V.; Wieser, M.; Spohn, T.; Horst, S. M.; Breuer, D.; Iess, L.; Helbert, J.; Heyner, D.; Humm, D. C.; De Pater, I.; Mousis, O.; Bagenal, F.; Sutton, S.; Hibbard, K.; Reynolds, E.; Glassmeier, K. H.

2015-12-01

Proposed for Discovery in 2015, IVO would launch in 2021, arrive at Jupiter in early 2026, and perform at least 9 fast flybys of Io. IVO satisfies the key science objectives of the Io Observer concept for New Frontiers. Science instruments include Narrow- and wide-angle cameras (from APL and UA), dual fluxgate magnetometers (UCLA), thermal mapper (DLR-Germany), ion and neutral mass spectrometer (UBE-Switzerland), and plasma ion analyzer (IRF-Sweden). For more on the mission see http://www.lpi.usra.edu/opag/meetings/feb2015/presentations/. Key measurements include: 1. High-resolution (<20 m/pixel) imaging of volcanic landforms and vent structures; 2. Regional surface changes every encounter; 3. Velocities and effusion rates of dynamic processes; 4. Mapping of 150 K to ≥1000 K surfaces at 0.5-20 km/pixel for volcanic history; 5. Peak color temperature of erupting lavas; 6. Melt fraction of the mantle from electromagnetic sounding; 7. Thickness of Io's lithosphere; 8. Constraints on Io's internal magnetic field; 9. Global pattern of endogenic heat flow driven by tidal heating; 10. Regional topographic anomalies; 11. Tidal k2 to constrain mantle rigidity; 12. Topography of tectonic landforms; 13. Structural changes since Voyager and Galileo imaging; 14. Neutral species in Io's atmosphere and exosphere; 15. SO2, OI, and other emissions (in eclipse); 16. Christiansen Frequency (CF) to constrain SiO2 of warm silicate lavas; 17. Surface color variations from 300-1000 nm; 18. Passive background temperatures to model diurnal T variations; 19. Neutral species in Io's vicinity; 20. Remote monitoring of Na cloud and Io Plasma Torus; 21. Variability of plasma and magnetic signatures; 22. Search for plumes on Europa's bright limb at high phase angles; and 23. Monitor Europa's surface color and albedo for changes. In summary, IVO will acquire a broad suite of measurements to understand how tidal heating drives dynamic phenomena on Io and in the Jupiter system.

Origin and Ion Charge State Evolution of Solar Wind Transients during 4 - 7 August 2011

NASA Astrophysics Data System (ADS)

Rodkin, D.; Goryaev, F.; Pagano, P.; Gibb, G.; Slemzin, V.; Shugay, Y.; Veselovsky, I.; Mackay, D. H.

2017-07-01

We present a study of the complex event consisting of several solar wind transients detected by the Advanced Composition Explorer (ACE) on 4 - 7 August 2011, which caused a geomagnetic storm with Dst=-110 nT. The supposed coronal sources, three flares and coronal mass ejections (CMEs), occurred on 2 - 4 August 2011 in active region (AR) 11261. To investigate the solar origin and formation of these transients, we study the kinematic and thermodynamic properties of the expanding coronal structures using the Solar Dynamics Observatory/Atmospheric Imaging Assembly (SDO/AIA) EUV images and differential emission measure (DEM) diagnostics. The Helioseismic and Magnetic Imager (HMI) magnetic field maps were used as the input data for the 3D magnetohydrodynamic (MHD) model to describe the flux rope ejection (Pagano, Mackay, and Poedts, 2013b). We characterize the early phase of the flux rope ejection in the corona, where the usual three-component CME structure formed. The flux rope was ejected with a speed of about 200 km s^{-1} to the height of 0.25 R_{⊙}. The kinematics of the modeled CME front agrees well with the Solar Terrestrial Relations Observatory (STEREO) EUV measurements. Using the results of the plasma diagnostics and MHD modeling, we calculate the ion charge ratios of carbon and oxygen as well as the mean charge state of iron ions of the 2 August 2011 CME, taking into account the processes of heating, cooling, expansion, ionization, and recombination of the moving plasma in the corona up to the frozen-in region. We estimate a probable heating rate of the CME plasma in the low corona by matching the calculated ion composition parameters of the CME with those measured in situ for the solar wind transients. We also consider the similarities and discrepancies between the results of the MHD simulation and the observations.

THE DISCREPANT KINEMATICS OF ORLs AND CELs IN NGC 7009 AS A FUNCTION OF IONIZATION STRUCTURE

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

Richer, Michael G.; Georgiev, Leonid; Torres-Peimbert, Silvia

2013-08-20

We present spatially and velocity-resolved echelle spectroscopy for NGC 7009 obtained with the UVES spectrograph at the European Southern Observatory's Very Large Telescope. Our objective is to analyze the kinematics of emission lines excited by recombination and collisions with electrons to determine whether similarities or differences could be useful in elucidating the well-known abundance discrepancy derived from them. We construct position-velocity maps for recombination, fluorescence, charge transfer, and collisionally excited lines. We find a plasma component emitting in the C II, N II, O II, and Ne II recombination lines whose kinematics are discrepant: they are incompatible with the ionizationmore » structure derived from all other evidence and the kinematics derived from all of these lines are unexpectedly very similar. We find direct evidence for a recombination contribution to [N II] {lambda}5755. Once taken into account, the electron temperatures from [N II], [O III], and [Ne III] agree at a given position and velocity. The electron densities derived from [O II] and [Ar IV] are consistent with direct imaging and the distribution of hydrogen emission. The kinematics of the C II, N II, O II, and Ne II lines does not coincide with the kinematics of the [O III] and [Ne III] forbidden emission, indicating that there is an additional plasma component to the recombination emission that arises from a different volume from that giving rise to the forbidden emission from the parent ions within NGC 7009. Thus, the chemical abundances derived from either type of line are correct only for the plasma component from which they arise. Apart from [N II] {lambda}5755, we find no anomaly with the forbidden lines usually used to determine chemical abundances in ionized nebulae, so the abundances derived from them should be reliable for the medium from which they arise.« less

Quantum Criticality and Black Holes

ScienceCinema

Sachdev, Subir [Harvard University, Cambridge, Massachusetts, United States

2017-12-09

I will describe the behavior of a variety of condensed matter systems in the vicinity of zero temperature quantum phase transitions. There is a remarkable analogy between the hydrodynamics of such systems and the quantum theory of black holes. I will show how insights from this analogy have shed light on recent experiments on the cuprate high temperature superconductors. Studies of new materials and trapped ultracold atoms are yielding new quantum phases, with novel forms of quantum entanglement. Some materials are of technological importance: e.g. high temperature superconductors. Exact solutions via black hole mapping have yielded first exact results for transport coefficients in interacting many-body systems, and were valuable in determining general structure of hydrodynamics. Theory of VBS order and Nernst effect in cuprates. Tabletop 'laboratories for the entire universe': quantum mechanics of black holes, quark-gluon plasma, neutrons stars, and big-bang physics.

Galileo Outreach Compilation

NASA Technical Reports Server (NTRS)

1998-01-01

This NASA JPL (Jet Propulsion Laboratory) video production is a compilation of the best short movies and computer simulation/animations of the Galileo spacecraft's journey to Jupiter. A limited number of actual shots are presented of Jupiter and its natural satellites. Most of the video is comprised of computer animations of the spacecraft's trajectory, encounters with the Galilean satellites Io, Europa and Ganymede, as well as their atmospheric and surface structures. Computer animations of plasma wave observations of Ganymede's magnetosphere, a surface gravity map of Io, the Galileo/Io flyby, the Galileo space probe orbit insertion around Jupiter, and actual shots of Jupiter's Great Red Spot are presented. Panoramic views of our Earth (from orbit) and moon (from orbit) as seen from Galileo as well as actual footage of the Space Shuttle/Galileo liftoff and Galileo's space probe separation are also included.

The Interaction of Melittin with Dimyristoyl Phosphatidylcholine-Dimyristoyl Phosphatidylserine Lipid Bilayer Membranes

DOE PAGES

Rai, Durgesh K.; Qian, Shuo; Heller, William T.

2016-08-13

We report that membrane-active peptides (MAPs), which interact directly with the lipid bilayer of a cell and include toxins and host defense peptides, display lipid composition-dependent activity. Phosphatidylserine (PS) lipids are anionic lipids that are found throughout the cellular membranes of most eukaryotic organisms where they serve as both a functional component and as a precursor to phosphatidylethanolamine lipids. The inner leaflet of the plasma membrane contains more PS than the outer one, and the asymmetry is actively maintained. Here, the impact of the MAP melittin on the structure of lipid bilayer vesicles made of a mixture of phosphatidylcholine andmore » phosphatidylserine was studied. Small-angle neutron scattering of the MAP associated with selectively deuterium-labeled lipid bilayer vesicles revealed how the thickness and lipid composition of phosphatidylserine-containing vesicles change in response to melittin. The peptide thickens the lipid bilayer for concentrations up to P/L = 1/500, but membrane thinning results when P/L = 1/200. The thickness transition is accompanied by a large change in the distribution of DMPS between the leaflets of the bilayer. The change in composition is driven by electrostatic interactions, while the change in bilayer thickness is driven by changes in the interaction of the peptide with the headgroup region of the lipid bilayer. Lastly, the results provide new information about lipid-specific interactions that take place in mixed composition lipid bilayer membranes.« less

The Interaction of Melittin with Dimyristoyl Phosphatidylcholine-Dimyristoyl Phosphatidylserine Lipid Bilayer Membranes.

PubMed

Rai, Durgesh K; Qian, Shuo; Heller, William T

2016-11-01

Membrane-active peptides (MAPs), which interact directly with the lipid bilayer of a cell and include toxins and host defense peptides, display lipid composition-dependent activity. Phosphatidylserine (PS) lipids are anionic lipids that are found throughout the cellular membranes of most eukaryotic organisms where they serve as both a functional component and as a precursor to phosphatidylethanolamine lipids. The inner leaflet of the plasma membrane contains more PS than the outer one, and the asymmetry is actively maintained. Here, the impact of the MAP melittin on the structure of lipid bilayer vesicles made of a mixture of phosphatidylcholine and phosphatidylserine was studied. Small-angle neutron scattering of the MAP associated with selectively deuterium-labeled lipid bilayer vesicles revealed how the thickness and lipid composition of phosphatidylserine-containing vesicles change in response to melittin. The peptide thickens the lipid bilayer for concentrations up to P/L=1/500, but membrane thinning results when P/L=1/200. The thickness transition is accompanied by a large change in the distribution of DMPS between the leaflets of the bilayer. The change in composition is driven by electrostatic interactions, while the change in bilayer thickness is driven by changes in the interaction of the peptide with the headgroup region of the lipid bilayer. The results provide new information about lipid-specific interactions that take place in mixed composition lipid bilayer membranes. Copyright © 2016 Elsevier B.V. All rights reserved.

Bifurcation structure of successive torus doubling

NASA Astrophysics Data System (ADS)

Sekikawa, Munehisa; Inaba, Naohiko; Yoshinaga, Tetsuya; Tsubouchi, Takashi

2006-01-01

The authors discuss the “embryology” of successive torus doubling via the bifurcation theory, and assert that the coupled map of a logistic map and a circle map has a structure capable of generating infinite number of torus doublings.

Gasdynamic Mirror Fusion Propulsion Experiment

NASA Technical Reports Server (NTRS)

Emrich, Bill; Rodgers, Stephen L. (Technical Monitor)

2000-01-01

A gasdynamic mirror (GDM) fusion propulsion experiment is currently being constructed at the NASA Marshall Space Flight Center (MSFC) to test the feasibility of this particular type of fusion device. Because of the open magnetic field line configuration of mirror fusion devices, they are particularly well suited for propulsion system applications since they allow for the easy ejection of thrust producing plasma. Currently, the MSFC GDM is constructed in three segments. The vacuum chamber mirror segment, the plasma injector mirror segment, and the main plasma chamber segment. Enough magnets are currently available to construct up to three main plasma chamber segments. The mirror segments are also segmented such that they can be expanded to accommodate new end plugging strategies with out requiring the disassembly of the entire mirror segment. The plasma for the experiment is generated in a microwave cavity located between the main magnets and the mirror magnets. Ion heating is accomplished through ambipolar diffusion. The objective of the experiment is to investigate the stability characteristics of the gasdynamic mirror and to map a region of parameter space within which the plasma can be confined in a stable steady state configuration. The mirror ratio, plasma density, and plasma "b" will be varied over a range of values and measurements subsequently taken to determine the degree of plasma stability.

A High Speed, Radiation Hard X-Ray Imaging Spectroscometer for Planetary Investigations

NASA Technical Reports Server (NTRS)

Kraft, R. P.; Kenter, A. T.; Murray, S. S.; Martindale, A.; Pearson, J.; Gladstone, R.; Branduardi-Raymont, G.; Elsner, R.; Kimura, T.; Ezoe, Y.;

SPM analysis of parametric (R)-[11C]PK11195 binding images: plasma input versus reference tissue parametric methods.

PubMed

Schuitemaker, Alie; van Berckel, Bart N M; Kropholler, Marc A; Veltman, Dick J; Scheltens, Philip; Jonker, Cees; Lammertsma, Adriaan A; Boellaard, Ronald

2007-05-01

(R)-[11C]PK11195 has been used for quantifying cerebral microglial activation in vivo. In previous studies, both plasma input and reference tissue methods have been used, usually in combination with a region of interest (ROI) approach. Definition of ROIs, however, can be labourious and prone to interobserver variation. In addition, results are only obtained for predefined areas and (unexpected) signals in undefined areas may be missed. On the other hand, standard pharmacokinetic models are too sensitive to noise to calculate (R)-[11C]PK11195 binding on a voxel-by-voxel basis. Linearised versions of both plasma input and reference tissue models have been described, and these are more suitable for parametric imaging. The purpose of this study was to compare the performance of these plasma input and reference tissue parametric methods on the outcome of statistical parametric mapping (SPM) analysis of (R)-[11C]PK11195 binding. Dynamic (R)-[11C]PK11195 PET scans with arterial blood sampling were performed in 7 younger and 11 elderly healthy subjects. Parametric images of volume of distribution (Vd) and binding potential (BP) were generated using linearised versions of plasma input (Logan) and reference tissue (Reference Parametric Mapping) models. Images were compared at the group level using SPM with a two-sample t-test per voxel, both with and without proportional scaling. Parametric BP images without scaling provided the most sensitive framework for determining differences in (R)-[11C]PK11195 binding between younger and elderly subjects. Vd images could only demonstrate differences in (R)-[11C]PK11195 binding when analysed with proportional scaling due to intersubject variation in K1/k2 (blood-brain barrier transport and non-specific binding).

Seminal plasma proteome of electroejaculated Bos indicus bulls.

PubMed

Rego, J P A; Crisp, J M; Moura, A A; Nouwens, A S; Li, Y; Venus, B; Corbet, N J; Corbet, D H; Burns, B M; Boe-Hansen, G B; McGowan, M R

2014-07-01

The present study describes the seminal plasma proteome of Bos indicus bulls. Fifty-six, 24-month old Australian Brahman sires were evaluated and subjected to electroejaculation. Seminal plasma proteins were separated by 2-D SDS-PAGE and identified by mass spectrometry. The percentage of progressively motile and morphologically normal sperm of the bulls were 70.4 ± 2.3 and 64 ± 3.2%, respectively. A total of 108 spots were identified in the 2-D maps, corresponding to 46 proteins. Binder of sperm proteins accounted for 55.8% of all spots detected in the maps and spermadhesins comprised the second most abundant constituents. Other proteins of the Bos indicus seminal plasma include clusterin, albumin, transferrin, metalloproteinase inhibitor 2, osteopontin, epididymal secretory protein E1, apolipoprotein A-1, heat shock 70 kDa protein, glutathione peroxidase 3, cathelicidins, alpha-enolase, tripeptidyl-peptidase 1, zinc-alpha-2-glycoprotein, plasma serine protease inhibitor, beta 2-microglobulin, proteasome subunit beta type-4, actin, cathepsins, nucleobinding-1, protein S100-A9, hemoglobin subunit alpha, cadherin-1, angiogenin-1, fibrinogen alpha and beta chain, ephirin-A1, protein DJ-1, serpin A3-7, alpha-2-macroglobulin, annexin A1, complement factor B, polymeric immunoglobulin receptor, seminal ribonuclease, ribonuclease-4, prostaglandin-H2 d-isomerase, platelet-activating factor acetylhydrolase, and phosphoglycerate kinase 1. In conclusion, this work uniquely portrays the Bos indicus seminal fluid proteome, based on samples from a large set of animals representing the Brahman cattle of the tropical Northern Australia. Based on putative biochemical attributes, seminal proteins act during sperm maturation, protection, capacitation and fertilization. Copyright © 2014. Published by Elsevier B.V.

Density functional theory calculations of continuum lowering in strongly coupled plasmas.

PubMed

Vinko, S M; Ciricosta, O; Wark, J S

2014-03-24

An accurate description of the ionization potential depression of ions in plasmas due to their interaction with the environment is a fundamental problem in plasma physics, playing a key role in determining the ionization balance, charge state distribution, opacity and plasma equation of state. Here we present a method to study the structure and position of the continuum of highly ionized dense plasmas using finite-temperature density functional theory in combination with excited-state projector augmented-wave potentials. The method is applied to aluminium plasmas created by intense X-ray irradiation, and shows excellent agreement with recently obtained experimental results. We find that the continuum lowering for ions in dense plasmas at intermediate temperatures is larger than predicted by standard plasma models and explain this effect through the electronic structure of the valence states in these strong-coupling conditions.

Double-ring structure formation of intense ion beams with finite radius in a pre-formed plasma

NASA Astrophysics Data System (ADS)

Hu, Zhang-Hu; Wang, Xiao-Juan; Zhao, Yong-Tao; Wang, You-Nian

2017-12-01

The dynamic structure evolution of intense ion beams with a large edge density gradient is investigated in detail with an analytical model and two-dimensional particle-in-cell (PIC) simulations, with special attention paid to the influence of beam radius. At the initial stage of beam-plasma interactions, the ring structure is formed due to the transverse focusing magnetic field induced by the unneutralized beam current in the beam edge region. As the beam-plasma system evolves self-consistently, a second ring structure appears in the case of ion beams with a radius much larger than the plasma skin depth, due to the polarity change in the transverse magnetic field in the central regions compared with the outer, focusing field. Influences of the current-filamentation and two-stream instability on the ring structure can be clearly observed in PIC simulations by constructing two different simulation planes.

Combining 3D structure of real video and synthetic objects

NASA Astrophysics Data System (ADS)

Kim, Man-Bae; Song, Mun-Sup; Kim, Do-Kyoon

1998-04-01

This paper presents a new approach of combining real video and synthetic objects. The purpose of this work is to use the proposed technology in the fields of advanced animation, virtual reality, games, and so forth. Computer graphics has been used in the fields previously mentioned. Recently, some applications have added real video to graphic scenes for the purpose of augmenting the realism that the computer graphics lacks in. This approach called augmented or mixed reality can produce more realistic environment that the entire use of computer graphics. Our approach differs from the virtual reality and augmented reality in the manner that computer- generated graphic objects are combined to 3D structure extracted from monocular image sequences. The extraction of the 3D structure requires the estimation of 3D depth followed by the construction of a height map. Graphic objects are then combined to the height map. The realization of our proposed approach is carried out in the following steps: (1) We derive 3D structure from test image sequences. The extraction of the 3D structure requires the estimation of depth and the construction of a height map. Due to the contents of the test sequence, the height map represents the 3D structure. (2) The height map is modeled by Delaunay triangulation or Bezier surface and each planar surface is texture-mapped. (3) Finally, graphic objects are combined to the height map. Because 3D structure of the height map is already known, Step (3) is easily manipulated. Following this procedure, we produced an animation video demonstrating the combination of the 3D structure and graphic models. Users can navigate the realistic 3D world whose associated image is rendered on the display monitor.

Dynamics of the plasma current sheath in plasma focus discharges in different gases

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

Vinogradov, V. P.; Krauz, V. I., E-mail: krauz-vi@nrcki.ru; Mokeev, A. N.

2016-12-15

The shape of the plasma current sheath (PCS) in the final stage of its radial compression, the dynamics of pinching, and the subsequent pinch decay in plasma focus (PF) discharges in different gases are studied using an improved multichannel system of electron-optical plasma photography and a newly elaborated synchronization system. The PCS structure in discharges in heavy gases (Ne, Ar) is found to differ significantly from that in discharges in hydrogen and deuterium. The influence of a heavy gas (Xe) additive to hydrogen and deuterium on the structure and compression dynamics of the PCS is investigated.

Trapped nonneutral plasmas, liquids, and crystals (the thermal equilibrium states)

NASA Astrophysics Data System (ADS)

Dubin, Daniel H.; O'neil, T. M.

1999-01-01

Plasmas consisting exclusively of particles with a single sign of charge (e.g., pure electron plasmas and pure ion plasmas) can be confined by static electric and magnetic fields (in a Penning trap) and also be in a state of global thermal equilibrium. This important property distinguishes these totally unneutralized plasmas from neutral and quasineutral plasmas. This paper reviews the conditions for, and the structure of, the thermal equilibrium states. Both theory and experiment are discussed, but the emphasis is decidedly on theory. It is a huge advantage to be able to use thermal equilibrium statistical mechanics to describe the plasma state. Such a description is easily obtained and complete, including for example the details of the plasma shape and microscopic order. Pure electron and pure ion plasmas are routinely confined for hours and even days, and thermal equilibrium states are observed. These plasmas can be cooled to the cryogenic temperature range, where liquid and crystal-like states are realized. The authors discuss the structure of the correlated states separately for three plasma sizes: large plasmas, in which the free energy is dominated by the bulk plasma; mesoscale plasmas, in which the free energy is strongly influenced by the surface; and Coulomb clusters, in which the number of particles is so small that the canonical ensemble is not a good approximation for the microcanonical ensemble. All three cases have been studied through numerical simulations, analytic theory, and experiment. In addition to describing the structure of the thermal equilibrium states, the authors develop a thermodynamic theory of the trapped plasma system. Thermodynamic inequalities and Maxwell relations provide useful bounds on and general relationships between partial derivatives of the various thermodynamic variables.

Structural characterization of nano-oxide layers in PtMn based specular spin valves

NASA Astrophysics Data System (ADS)

Zhou, Min; Chen, Lifan; Diao, Zhitao; Park, Chang-Man; Huai, Yiming

2005-05-01

A systematic structure characterization of nano-oxide layers (NOLs) and specular spin valves using x-ray diffraction and high-resolution transmission electron microscopy (HRTEM) has been studied. High-angle x-ray diffraction data show almost identical fcc textures for both natural and plasma NOL spin-valves. Low-angle x-ray reflectivity spectrum shows more deteriorated Kiessig fringes at high incident angles for natural oxide sample, indicating rougher interfaces in natural oxidation than in plasma oxidation. Oxygen exposure plays an important role in NOLs process. Fabricating NOLs without any crystal structure degradation is critical to obtain high MR ratio. HRTEM reveals that oxide clusters mixing with insufficiently oxidized CoFe layers prevailed in natural NOL, and the natural oxidation was inhomogeneous. In contrast, plasma NOL has a thinner, more homogeneously oxidized CoFe layers with sharp interfaces. In plasma NOLs, the structures still maintain CoFe crystal structure. The structures and magnetic correlation of the NOL specular spin valves are discussed.

Nonlinear electric field structures in the inner magnetosphere

DOE PAGES

Malaspina, D. M.; Andersson, L.; Ergun, R. E.; ...

2014-08-28

Recent observations by the Van Allen Probes spacecraft have demonstrated that a variety of electric field structures and nonlinear waves frequently occur in the inner terrestrial magnetosphere, including phase space holes, kinetic field-line resonances, nonlinear whistler-mode waves, and several types of double layer. However, it is nuclear whether such structures and waves have a significant impact on the dynamics of the inner magnetosphere, including the radiation belts and ring current. To make progress toward quantifying their importance, this study statistically evaluates the correlation of such structures and waves with plasma boundaries. A strong correlation is found. These statistical results, combinedmore » with observations of electric field activity at propagating plasma boundaries, are consistent with the identification of these boundaries as the source of free energy responsible for generating the electric field structures and nonlinear waves of interest. Therefore, the ability of these structures and waves to influence plasma in the inner magnetosphere is governed by the spatial extent and dynamics of macroscopic plasma boundaries in that region.« less

Turbulence experiments on the PKU Plasma Test (PPT) device

NASA Astrophysics Data System (ADS)

Xu, Tianchao; Xiao, Chijie; Yang, Xiaoyi; Chen, Yihang; Yu, Yi; Xu, Min; Wang, Long; Lin, Chen; Wang, Xiaogang

2017-10-01

The PKU Plasma Test (PPT) device is a linear plasma device in Peking University, China. It has a vacuum chamber with 1000mm length and 500mm diameter. A pair of Helmholtz coils can generate toroidal magnetic field up to 2000 Gauss, and plasma was generated by a helicon source. Probes and fast camera were used to diagnose the parameters and got the turbulence spectrums, coherent structure, etc. The dynamics of turbulence, coherent structure and parameter profiles have been analyzed, and it has been found that the turbulence states are related to the equilibrium profiles; Some coherent structures exist and show strongly interactions with the background turbulences; The spatial and temporal evolutions of these coherent structures are related to the amplitude of the density gradient and electric field. These results will help on further studies of plasma transport. This work was supported by the National Natural Science Foundation of China under 11575014 and 11375053, CHINA MOST under 2012YQ030142 and ITER-CHINA program 2015GB120001.

Parametric computational study of sheaths in multicomponent Ar/O2 plasma

NASA Astrophysics Data System (ADS)

Hromadka, J.; Ibehej, T.; Hrach, R.

2018-02-01

Our study is devoted to sheath structures emerging in Ar/O2 plasma. By means of two dimensional PIC/MCC computer model two configurations were investigated - sheath structure in the vicinity of a cylindrical Langmuir probe for two different biases and changes of the sheath structure when a cylindrical probe passes into a semi-planar probe. It was shown that O+ ions play important role in shielding out negative bias of a solid immersed in Ar/O2 plasma and edge effects of a semi-planar probe on its sheath structure were evaluated.

Optical Activation of Germanium Plasmonic Antennas in the Mid-Infrared

NASA Astrophysics Data System (ADS)

Fischer, Marco P.; Schmidt, Christian; Sakat, Emilie; Stock, Johannes; Samarelli, Antonio; Frigerio, Jacopo; Ortolani, Michele; Paul, Douglas J.; Isella, Giovanni; Leitenstorfer, Alfred; Biagioni, Paolo; Brida, Daniele

2016-07-01

Impulsive interband excitation with femtosecond near-infrared pulses establishes a plasma response in intrinsic germanium structures fabricated on a silicon substrate. This direct approach activates the plasmonic resonance of the Ge structures and enables their use as optical antennas up to the mid-infrared spectral range. The optical switching lasts for hundreds of picoseconds until charge recombination redshifts the plasma frequency. The full behavior of the structures is modeled by the electrodynamic response established by an electron-hole plasma in a regular array of antennas.

Optical Activation of Germanium Plasmonic Antennas in the Mid-Infrared.

PubMed

Fischer, Marco P; Schmidt, Christian; Sakat, Emilie; Stock, Johannes; Samarelli, Antonio; Frigerio, Jacopo; Ortolani, Michele; Paul, Douglas J; Isella, Giovanni; Leitenstorfer, Alfred; Biagioni, Paolo; Brida, Daniele

2016-07-22

Impulsive interband excitation with femtosecond near-infrared pulses establishes a plasma response in intrinsic germanium structures fabricated on a silicon substrate. This direct approach activates the plasmonic resonance of the Ge structures and enables their use as optical antennas up to the mid-infrared spectral range. The optical switching lasts for hundreds of picoseconds until charge recombination redshifts the plasma frequency. The full behavior of the structures is modeled by the electrodynamic response established by an electron-hole plasma in a regular array of antennas.

Experimental investigation of coaxial-gun-formed plasmas injected into a background transverse magnetic field or plasma

NASA Astrophysics Data System (ADS)

Zhang, Yue; Fisher, Dustin M.; Gilmore, Mark; Hsu, Scott C.; Lynn, Alan G.

2018-05-01

Injection of coaxial-gun-formed magnetized plasmas into a background transverse vacuum magnetic field or into a background magnetized plasma has been studied in the helicon-cathode (HelCat) linear plasma device at the University of New Mexico [M. Gilmore et al., J. Plasma Phys. 81, 345810104 (2015)]. A magnetized plasma jet launched into a background transverse magnetic field shows emergent kink stabilization of the jet due to the formation of a sheared flow in the jet above the kink stabilization threshold 0.1kVA [Y. Zhang et al., Phys. Plasmas 24, 110702 (2017)]. Injection of a spheromak-like plasma into a transverse background magnetic field led to the observation of finger-like structures on the side with a stronger magnetic field null between the spheromak and the background field. The finger-like structures are consistent with magneto-Rayleigh-Taylor instability. Jets or spheromaks launched into a background, low-β magnetized plasma show similar behavior as above, respectively, in both cases.

GIANT LOBES OF CENTAURUS A RADIO GALAXY OBSERVED WITH THE SUZAKU X-RAY SATELLITE

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

Stawarz, L.; Gandhi, P.; Takahashi, T.

2013-03-20

We report on Suzaku observations of selected regions within the southern giant lobe of the radio galaxy Centaurus A. In our analysis we focus on distinct X-ray features detected with the X-ray Imaging Spectrometer within the range 0.5-10 keV, some of which are likely associated with fine structure of the lobe revealed by recent high-quality radio intensity and polarization maps. With the available photon statistics, we find that the spectral properties of the detected X-ray features are equally consistent with thermal emission from hot gas with temperatures kT > 1 keV, or with a power-law radiation continuum characterized by photonmore » indices {Gamma} {approx} 2.0 {+-} 0.5. However, the plasma parameters implied by these different models favor a synchrotron origin for the analyzed X-ray spots, indicating that a very efficient acceleration of electrons up to {approx}> 10 TeV energies is taking place within the giant structure of Centaurus A, albeit only in isolated and compact regions associated with extended and highly polarized radio filaments. We also present a detailed analysis of the diffuse X-ray emission filling the whole field of view of the instrument, resulting in a tentative detection of a soft excess component best fitted by a thermal model with a temperature of kT {approx} 0.5 keV. The exact origin of the observed excess remains uncertain, although energetic considerations point to thermal gas filling the bulk of the volume of the lobe and mixed with the non-thermal plasma, rather than to the alternative scenario involving a condensation of the hot intergalactic medium around the edges of the expanding radio structure. If correct, this would be the first detection of the thermal content of the extended lobes of a radio galaxy in X-rays. The corresponding number density of the thermal gas in such a case is n{sub g} {approx} 10{sup -4} cm{sup -3}, while its pressure appears to be in almost exact equipartition with the volume-averaged non-thermal pressure provided by the radio-emitting electrons and the lobes' magnetic field. A prominent large-scale fluctuation of the Galactic foreground emission, resulting in excess foreground X-ray emission aligned with the lobe, cannot be ruled out. Although tentative, our findings potentially imply that the structure of the extended lobes in active galaxies is likely to be highly inhomogeneous and non-uniform, with magnetic reconnection and turbulent acceleration processes continuously converting magnetic energy to internal energy of the plasma particles, leading to possibly significant spatial and temporal variations in the plasma {beta} parameter around the volume-averaged equilibrium condition {beta} {approx} 1.« less

Dual-function magnetic structure for toroidal plasma devices

DOEpatents

Brown, Robert L.

1978-01-01

This invention relates to a support system wherein the iron core and yoke of the plasma current system of a tokamak plasma containment device is redesigned to support the forces of the magnet coils. The containment rings, which occupy very valuable space around the magnet coils, are utilized to serve as yokes for the core such that the conventional yoke is eliminated. The overall result is an improved aspect ratio, reduction in structure, smaller overall size, and improved access to the plasma ring.

The effect of internal magnetic structure on the fishbone instability

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

Roberts, D.W.; Powell, E.; Kaita, R.

1992-01-01

Plasmas exhibiting the ``fishbone`` instability studied on the PBX-M tokamak show a distinct relationship between the plasma shape, the internal magnetic structure, and the presence or absence of fast ion losses associated with the fishbone mode. We have, for the first time, carried out measurements of the magnetic safety factor profile in fishbone-unstable plasmas, and used the knowledge of the associated experimental equilibria to compare the stability and fast ion loss properties of these plasmas with experimental observations.

The effect of internal magnetic structure on the fishbone instability

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

Roberts, D.W.; Powell, E.; Kaita, R.

1992-01-01

Plasmas exhibiting the fishbone'' instability studied on the PBX-M tokamak show a distinct relationship between the plasma shape, the internal magnetic structure, and the presence or absence of fast ion losses associated with the fishbone mode. We have, for the first time, carried out measurements of the magnetic safety factor profile in fishbone-unstable plasmas, and used the knowledge of the associated experimental equilibria to compare the stability and fast ion loss properties of these plasmas with experimental observations.

Study of ultrasound-assisted radio-frequency plasma discharges in n-dodecane

NASA Astrophysics Data System (ADS)

Camerotto, Elisabeth; De Schepper, Peter; Nikiforov, Anton Y.; Brems, Steven; Shamiryan, Denis; Boullart, Werner; Leys, Christophe; De Gendt, Stefan

2012-10-01

This paper investigates the generation of a stable plasma phase in a liquid hydrocarbon (n-dodecane) by means of ultrasound (US) and radio-frequency (RF) or electromagnetic radiation. It is demonstrated for the first time that ultrasonic aided RF plasma discharges can be generated in a liquid. Plasma discharges are obtained for different gas mixtures at a pressure of 12 kPa and at low ignition powers (100 W for RF and 2.4 W cm-2 for US). Direct carbon deposition from the liquid precursor on Cu, Ni, SiO2 and Si substrates has been obtained and no apparent compositional or structural difference among the substrate materials was observed. Characterization of the deposited solid phase revealed an amorphous structure. In addition, structural changes in the liquid precursor after plasma treatment have been analysed. Optical emission spectroscopy (OES) allowed the estimation of several plasma characteristic temperatures. The plasma excitation temperature was estimated to be about 2.3-2.4 eV. The rotational and vibrational temperatures of the discharge in n-dodecane with Ar as a feed gas were 1400 K and 6500 K, respectively. In Ar/O2 plasma, an increased rotational (1630 K) and vibrational temperature (7200 K) were obtained.

Experiments on Alfv'en waves in high beta plasmas

NASA Astrophysics Data System (ADS)

Gekelman, Walter; Pribyl, Patrick; Cooper, Chris; Vincena, Stephen

2008-11-01

The propagation of Alfv'en waves in high beta plasmas is of great interest in solar wind studies as well as in astrophysical plasmas. Alfv'en wave propagation in a high beta plasma is studied on the axis of a toroidal device at UCLA. The vacuum vessel is 30 meters in circumference, 2 meters wide and 3 meters tall. The plasma has a cross sectional area of 20 cm^2 and can be as long as 120 m which is hundreds of parallel Alfv'en wavelengths. The waves are launched using two orthogonal 5-turn , 5.7 cm diameter loops. The AC currents (10 kHz < f < 250 kHz) to the loops are as high as 2 kA p-p, producing fields of 1 kG on the axis of the antenna. The antenna coils are independently driven such that waves with arbitrary polarization can be launched. Movable three axis magnetic pickup loops detect the wave and are used to construct field maps in the machine. Wave propagation results as a function of plasma beta and input wave energy will be presented.

Validating Laser-Induced Birefringence Theory with Plasma Interferometry

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

Chen, Cecilia; Cornell Univ., Ithaca, NY

2015-09-02

Intense laser beams crossing paths in plasma is theorized to induce birefringence in the medium, resulting from density and refractive index modulations that affect the polarization of incoming light. The goal of the associated experiment, conducted on Janus at Lawrence Livermore’s Jupiter Laser Facility, was to create a tunable laser-plasma waveplate to verify the relationship between dephasing angle and beam intensity, plasma density, plasma temperature, and interaction length. Interferometry analysis of the plasma channel was performed to obtain a density map and to constrain temperature measured from Thomson scattering. Various analysis techniques, including Fast Fourier transform (FFT) and two variationsmore » of fringe-counting, were tried because interferograms captured in this experiment contained unusual features such as fringe discontinuity at channel edges, saddle points, and islands. The chosen method is flexible, semi-automated, and uses a fringe tracking algorithm on a reduced image of pre-traced synthetic fringes. Ultimately, a maximum dephasing angle of 49.6° was achieved using a 1200 μm interaction length, and the experimental results appear to agree with predictions.« less

Effects and Mechanism of Atmospheric-Pressure Dielectric Barrier Discharge Cold Plasma on Lactate Dehydrogenase (LDH) Enzyme

NASA Astrophysics Data System (ADS)

Zhang, Hao; Xu, Zimu; Shen, Jie; Li, Xu; Ding, Lili; Ma, Jie; Lan, Yan; Xia, Weidong; Cheng, Cheng; Sun, Qiang; Zhang, Zelong; Chu, Paul K.

2015-05-01

Proteins are carriers of biological functions and the effects of atmospheric-pressure non-thermal plasmas on proteins are important to applications such as sterilization and plasma-induced apoptosis of cancer cells. Herein, we report our detailed investigation of the effects of helium-oxygen non-thermal dielectric barrier discharge (DBD) plasmas on the inactivation of lactate dehydrogenase (LDH) enzyme solutions. Circular dichroism (CD) and dynamic light scattering (DLS) indicate that the loss of activity stems from plasma-induced modification of the secondary molecular structure as well as polymerization of the peptide chains. Raising the treatment intensity leads to a reduced alpha-helix content, increase in the percentage of the beta-sheet regions and random sequence, as well as gradually decreasing LDH activity. However, the structure of the LDH plasma-treated for 300 seconds exhibits a recovery trend after storage for 24 h and its activity also increases slightly. By comparing direct and indirect plasma treatments, plasma-induced LDH inactivation can be attributed to reactive species (RS) in the plasma, especially ones with a long lifetime including hydrogen peroxide, ozone, and nitrate ion which play the major role in the alteration of the macromolecular structure and molecular diameter in lieu of heat, UV radiation, and charged particles.

Apparatus and method for plasma processing of SRF cavities

NASA Astrophysics Data System (ADS)

Upadhyay, J.; Im, Do; Peshl, J.; Bašović, M.; Popović, S.; Valente-Feliciano, A.-M.; Phillips, L.; Vušković, L.

2016-05-01

An apparatus and a method are described for plasma etching of the inner surface of superconducting radio frequency (SRF) cavities. Accelerator SRF cavities are formed into a variable-diameter cylindrical structure made of bulk niobium, for resonant generation of the particle accelerating field. The etch rate non-uniformity due to depletion of the radicals has been overcome by the simultaneous movement of the gas flow inlet and the inner electrode. An effective shape of the inner electrode to reduce the plasma asymmetry for the coaxial cylindrical rf plasma reactor is determined and implemented in the cavity processing method. The processing was accomplished by moving axially the inner electrode and the gas flow inlet in a step-wise way to establish segmented plasma columns. The test structure was a pillbox cavity made of steel of similar dimension to the standard SRF cavity. This was adopted to experimentally verify the plasma surface reaction on cylindrical structures with variable diameter using the segmented plasma generation approach. The pill box cavity is filled with niobium ring- and disk-type samples and the etch rate of these samples was measured.

SSMap: a new UniProt-PDB mapping resource for the curation of structural-related information in the UniProt/Swiss-Prot Knowledgebase.

PubMed

David, Fabrice P A; Yip, Yum L

2008-09-23

Sequences and structures provide valuable complementary information on protein features and functions. However, it is not always straightforward for users to gather information concurrently from the sequence and structure levels. The UniProt knowledgebase (UniProtKB) strives to help users on this undertaking by providing complete cross-references to Protein Data Bank (PDB) as well as coherent feature annotation using available structural information. In this study, SSMap - a new UniProt-PDB residue-residue level mapping - was generated. The primary objective of this mapping is not only to facilitate the two tasks mentioned above, but also to palliate a number of shortcomings of existent mappings. SSMap is the first isoform sequence-specific mapping resource and is up-to-date for UniProtKB annotation tasks. The method employed by SSMap differs from the other mapping resources in that it stresses on the correct reconstruction of the PDB sequence from structures, and on the correct attribution of a UniProtKB entry to each PDB chain by using a series of post-processing steps. SSMap was compared to other existing mapping resources in terms of the correctness of the attribution of PDB chains to UniProtKB entries, and of the quality of the pairwise alignments supporting the residue-residue mapping. It was found that SSMap shared about 80% of the mappings with other mapping sources. New and alternative mappings proposed by SSMap were mostly good as assessed by manual verification of data subsets. As for local pairwise alignments, it was shown that major discrepancies (both in terms of alignment lengths and boundaries), when present, were often due to differences in methodologies used for the mappings. SSMap provides an independent, good quality UniProt-PDB mapping. The systematic comparison conducted in this study allows the further identification of general problems in UniProt-PDB mappings so that both the coverage and the quality of the mappings can be systematically improved for the benefit of the scientific community. SSMap mapping is currently used to provide PDB cross-references in UniProtKB.

Correlation of Tumor Immunohistochemistry with Dynamic Contrast-Enhanced and DSC-MRI Parameters in Patients with Gliomas.

PubMed

Nguyen, T B; Cron, G O; Bezzina, K; Perdrizet, K; Torres, C H; Chakraborty, S; Woulfe, J; Jansen, G H; Thornhill, R E; Zanette, B; Cameron, I G

2016-12-01

Tumor CBV is a prognostic and predictive marker for patients with gliomas. Tumor CBV can be measured noninvasively with different MR imaging techniques; however, it is not clear which of these techniques most closely reflects histologically-measured tumor CBV. Our aim was to investigate the correlations between dynamic contrast-enhanced and DSC-MR imaging parameters and immunohistochemistry in patients with gliomas. Forty-three patients with a new diagnosis of glioma underwent a preoperative MR imaging examination with dynamic contrast-enhanced and DSC sequences. Unnormalized and normalized cerebral blood volume was obtained from DSC MR imaging. Two sets of plasma volume and volume transfer constant maps were obtained from dynamic contrast-enhanced MR imaging. Plasma volume obtained from the phase-derived vascular input function and bookend T1 mapping (Vp_Φ) and volume transfer constant obtained from phase-derived vascular input function and bookend T1 mapping (K trans _Φ) were determined. Plasma volume obtained from magnitude-derived vascular input function (Vp_SI) and volume transfer constant obtained from magnitude-derived vascular input function (K trans _SI) were acquired, without T1 mapping. Using CD34 staining, we measured microvessel density and microvessel area within 3 representative areas of the resected tumor specimen. The Mann-Whitney U test was used to test for differences according to grade and degree of enhancement. The Spearman correlation was performed to determine the relationship between dynamic contrast-enhanced and DSC parameters and histopathologic measurements. Microvessel area, microvessel density, dynamic contrast-enhanced, and DSC-MR imaging parameters varied according to the grade and degree of enhancement (P < .05). A strong correlation was found between microvessel area and Vp_Φ and between microvessel area and unnormalized blood volume (r s ≥ 0.61). A moderate correlation was found between microvessel area and normalized blood volume, microvessel area and Vp_SI, microvessel area and K trans _Φ, microvessel area and K trans _SI, microvessel density and Vp_Φ, microvessel density and unnormalized blood volume, and microvessel density and normalized blood volume (0.44 ≤ r s ≤ 0.57). A weaker correlation was found between microvessel density and K trans _Φ and between microvessel density and K trans _SI (r s ≤ 0.41). With dynamic contrast-enhanced MR imaging, use of a phase-derived vascular input function and bookend T1 mapping improves the correlation between immunohistochemistry and plasma volume, but not between immunohistochemistry and the volume transfer constant. With DSC-MR imaging, normalization of tumor CBV could decrease the correlation with microvessel area. © 2016 by American Journal of Neuroradiology.

Yetter-Drinfeld modules for Hom-bialgebras

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

Makhlouf, Abdenacer, E-mail: Abdenacer.Makhlouf@uha.fr; Panaite, Florin, E-mail: Florin.Panaite@imar.ro

The aim of this paper is to define and study Yetter-Drinfeld modules over Hom-bialgebras, a generalized version of bialgebras obtained by modifying the algebra and coalgebra structures by a homomorphism. Yetter-Drinfeld modules over a Hom-bialgebra with bijective structure map provide solutions of the Hom-Yang-Baxter equation. The category H/HYD of Yetter-Drinfeld modules with bijective structure maps over a Hom-bialgebra H with bijective structure map can be organized, in two different ways, as a quasi-braided pre-tensor category. If H is quasitriangular (respectively, coquasitriangular) the first (respectively, second) quasi-braided pre-tensor category H/HYD contains, as a quasi-braided pre-tensor subcategory, the category of modules (respectively,more » comodules) with bijective structure maps over H.« less

An experimental study of icing control using DBD plasma actuator

NASA Astrophysics Data System (ADS)

Cai, Jinsheng; Tian, Yongqiang; Meng, Xuanshi; Han, Xuzhao; Zhang, Duo; Hu, Haiyang

2017-08-01

Ice accretion on aircraft or wind turbine has been widely recognized as a big safety threat in the past decades. This study aims to develop a new approach for icing control using an AC-DBD plasma actuator. The experiments of icing control (i.e., anti-/de-icing) on a cylinder model were conducted in an icing wind tunnel with controlled wind speed (i.e., 15 m/s) and temperature (i.e., -10°C). A digital camera was used to record the dynamic processes of plasma anti-icing and de-icing whilst an infrared imaging system was utilized to map the surface temperature variations during the anti-/de-icing processes. It was found that the AC-DBD plasma actuator is very effective in both anti-icing and de-icing operations. While no ice formation was observed when the plasma actuator served as an anti-icing device, a complete removal of the ice layer with a thickness of 5 mm was achieved by activating the plasma actuator for ˜150 s. Such information demonstrated the feasibility of plasma anti-/de-icing, which could potentially provide more effective and safer icing mitigation strategies.

Experimental Study of RF Sheaths due to Shear Alfvén Waves in the LAPD

NASA Astrophysics Data System (ADS)

Martin, Michael; Gekelman, Walter; van Compernolle, Bart; Pribyl, Patrick; Carter, Troy

2014-10-01

Ion cyclotron resonance heating (ICRH) is an important tool in current fusion heating experiments and will be an essential part of heating power in ITER. Radio frequency (RF) sheaths in the near-field (at the antenna) and in the far-field (e.g. the divertor region) form during ICRH and may cause deleterious effects, such as destruction of wall materials and plasma impurity generation. In this study a shear Alfvén wave is launched from an antenna in the LAPD bulk plasma (ne ~ 1012 cm-3, Te ~ 5 eV, B0 = 1.8 kG, diameter = 60 cm, length = 18 m) and forms an RF sheath on a limiter plate. Plasma potential rectification is observed with an emissive probe in the bulk plasma only on field lines connected to the limiter. The largest enhancement occurs inside the current channel of the Alfvén wave. Plasma potential measurements at various axial distances from the limiter show the rectification decreases with distance. 2-D maps of plasma potential as well as E = - ∇Φ will be presented. The scaling of sheath potential with wave power and plasma parameters will also be shown.

COASTING ARC ION SOURCE

DOEpatents

Foster, J.S. Jr.

1957-09-10

An improved ion source is described and in particular a source in which the ions are efficiently removed. The plasma is generated in a tubular amode structure by the oscillation of electrons in an axial magnetic field, as in the Phillips Ion Gage. The novel aspect of the source is the expansion of the plasma as it leaves the anode structure, so as to reduce the ion density at the axis of the anode and present a uniform area of plasma to an extraction grid. The structure utilized in the present patent to expand the plasma comprises flange members of high permeability at the exitgrid end of the amode to diverge the magnetic field adjacent the exit.

Periodical plasma structures controlled by external magnetic field

NASA Astrophysics Data System (ADS)

Schweigert, I. V.; Keidar, M.

2017-11-01

The plasma of Hall thruster type in external magnetic field is studied in 2D3V kinetic simulations using PIC MCC method. The periodical structure with maxima of electron and ion densities is formed and becomes more pronounced with increase of magnetic field incidence angle in the plasma. These ridges of electron and ion densities are aligned with the magnetic field vector and shifted relative each other. This leads to formation of two-dimensional double-layers structure in cylindrical plasma chamber. Depending on Larmor radius and Debye length up to nineteen potential steps appear across the oblique magnetic field. The electrical current gathered on the wall is associated with the electron and ion density ridges.

Modeling adsorption properties of structurally deformed metal–organic frameworks using structure–property map

PubMed Central

Lim, Dae-Woon; Kim, Sungjune; Harale, Aadesh; Yoon, Minyoung; Suh, Myunghyun Paik; Kim, Jihan

2017-01-01

Structural deformation and collapse in metal-organic frameworks (MOFs) can lead to loss of long-range order, making it a challenge to model these amorphous materials using conventional computational methods. In this work, we show that a structure–property map consisting of simulated data for crystalline MOFs can be used to indirectly obtain adsorption properties of structurally deformed MOFs. The structure–property map (with dimensions such as Henry coefficient, heat of adsorption, and pore volume) was constructed using a large data set of over 12000 crystalline MOFs from molecular simulations. By mapping the experimental data points of deformed SNU-200, MOF-5, and Ni-MOF-74 onto this structure–property map, we show that the experimentally deformed MOFs share similar adsorption properties with their nearest neighbor crystalline structures. Once the nearest neighbor crystalline MOFs for a deformed MOF are selected from a structure–property map at a specific condition, then the adsorption properties of these MOFs can be successfully transformed onto the degraded MOFs, leading to a new way to obtain properties of materials whose structural information is lost. PMID:28696307

Hemocompatibility of poly(vinylidene fluoride) membrane grafted with network-like and brush-like antifouling layer controlled via plasma-induced surface PEGylation.

PubMed

Chang, Yung; Shih, Yu-Ju; Ko, Chao-Yin; Jhong, Jheng-Fong; Liu, Ying-Ling; Wei, Ta-Chin

2011-05-03

In this work, the hemocompatibility of PEGylated poly(vinylidene fluoride) (PVDF) microporous membranes with varying grafting coverage and structures via plasma-induced surface PEGylation was studied. Network-like and brush-like PEGylated layers on PVDF membrane surfaces were achieved by low-pressure and atmospheric plasma treatment. The chemical composition, physical morphology, grafting structure, surface hydrophilicity, and hydration capability of prepared membranes were determined to illustrate the correlations between grafting qualities and hemocompatibility of PEGylated PVDF membranes in contact with human blood. Plasma protein adsorption onto different PEGylated PVDF membranes from single-protein solutions and the complex medium of 100% human plasma were measured by enzyme-linked immunosorbent assay (ELISA) with monoclonal antibodies. Hemocompatibility of the PEGylated membranes was evaluated by the antifouling property of platelet adhesion observed by scanning electron microscopy (SEM) and the anticoagulant activity of the blood coagulant determined by testing plasma-clotting time. The control of grafting structures of PEGylated layers highly regulates the PVDF membrane to resist the adsorption of plasma proteins, the adhesion of platelets, and the coagulation of human plasma. It was found that PVDF membranes grafted with brush-like PEGylated layers presented higher hydration capability with binding water molecules than with network-like PEGylated layers to improve the hemocompatible character of plasma protein and blood platelet resistance in human blood. This work suggests that the hemocompatible nature of grafted PEGylated polymers by controlling grafting structures gives them great potential in the molecular design of antithrombogenic membranes for use in human blood.

Nonlinear screening of dust grains and structurization of dusty plasma: II. formation and stability of dust structures

NASA Astrophysics Data System (ADS)

Tsytovich, V. N.; Gusein-zade, N. G.; Ignatov, A. M.

2017-10-01

The second part of the review on dust structures (the first part was published in Plasma Phys. Rep. 39, 515 (2013)) is devoted to experimental and theoretical studies on the stability of structures and their formation from the initially uniform dusty plasma components. The applicability limits of theoretical results and the role played by nonlinearity in the screening of dust grains are considered. The importance of nonlinearity is demonstrated by using numerous laboratory observations of planar clusters and volumetric dust structures. The simplest compact agglomerates of dust grains in the form of stable planar clusters are discussed. The universal character of instability resulting in the structurization of an initially uniform dusty plasma is shown. The fundamental correlations described in the first part of the review, supplemented with effects of dust inertia and dust friction by the neutral gas, are use to analyze structurization instability. The history of the development of theoretical ideas on the physics of the cluster formation for different types of interaction between dust grains is described.

Translation from the collaborative OSM database to cartography

NASA Astrophysics Data System (ADS)

Hayat, Flora

2018-05-01

The OpenStreetMap (OSM) database includes original items very useful for geographical analysis and for creating thematic maps. Contributors record in the open database various themes regarding amenities, leisure, transports, buildings and boundaries. The Michelin mapping department develops map prototypes to test the feasibility of mapping based on OSM. To translate the OSM database structure into a database structure fitted with Michelin graphic guidelines a research project is in development. It aims at defining the right structure for the Michelin uses. The research project relies on the analysis of semantic and geometric heterogeneities in OSM data. In that order, Michelin implements methods to transform the input geographical database into a cartographic image dedicated for specific uses (routing and tourist maps). The paper focuses on the mapping tools available to produce a personalised spatial database. Based on processed data, paper and Web maps can be displayed. Two prototypes are described in this article: a vector tile web map and a mapping method to produce paper maps on a regional scale. The vector tile mapping method offers an easy navigation within the map and within graphic and thematic guide- lines. Paper maps can be partly automatically drawn. The drawing automation and data management are part of the mapping creation as well as the final hand-drawing phase. Both prototypes have been set up using the OSM technical ecosystem.

Evaluating Uncertainties in Coronal Electron Temperature and Radial Speed Measurements Using a Simulation of the Bastille Day Eruption

NASA Astrophysics Data System (ADS)

Reginald, Nelson; St. Cyr, Orville; Davila, Joseph; Rastaetter, Lutz; Török, Tibor

2018-05-01

Obtaining reliable measurements of plasma parameters in the Sun's corona remains an important challenge for solar physics. We previously presented a method for producing maps of electron temperature and speed of the solar corona using K-corona brightness measurements made through four color filters in visible light, which were tested for their accuracies using models of a structured, yet steady corona. In this article we test the same technique using a coronal model of the Bastille Day (14 July 2000) coronal mass ejection, which also contains quiet areas and streamers. We use the coronal electron density, temperature, and flow speed contained in the model to determine two K-coronal brightness ratios at (410.3, 390.0 nm) and (423.3, 398.7 nm) along more than 4000 lines of sight. Now assuming that for real observations, the only information we have for each line of sight are these two K-coronal brightness ratios, we use a spherically symmetric model of the corona that contains no structures to interpret these two ratios for electron temperature and speed. We then compare the interpreted (or measured) values for each line of sight with the true values from the model at the plane of the sky for that same line of sight to determine the magnitude of the errors. We show that the measured values closely match the true values in quiet areas. However, in locations of coronal structures, the measured values are predictably underestimated or overestimated compared to the true values, but can nevertheless be used to determine the positions of the structures with respect to the plane of the sky, in front or behind. Based on our results, we propose that future white-light coronagraphs be equipped to image the corona using four color filters in order to routinely create coronal maps of electron density, temperature, and flow speed.

Plasma Accelerator Development for Dynamic Formation of Plasma Liners: A Status Report

NASA Technical Reports Server (NTRS)

Thio, Y. C. Francis; Eskridge, Richard; Martin, Adam; Smith, James; Lee, Michael; Rodgers, Stephen L. (Technical Monitor)

2001-01-01

An experimental plasma accelerator for magnetic target fusion (MTF) applications under development at the NASA Marshall Space Flight Center is described. The accelerator is a pulsed plasma thruster and has been tested experimentally and plasma jet velocities of approximately 50 km/sec have been obtained. The plasma jet structure has been photographed with 10 ns exposure times to reveal a stable and repeatable plasma structure. Data for velocity profile information has been obtained using light pipes embedded in the gun walls to record the plasma transit at various barrel locations. Preliminary spatially resolved spectral data and magnetic field probe data are also presented. A high speed triggering system has been developed and tested as a means of reducing the gun "jitter". This jitter is being characterized and future work for second generation "ultra-low jitter" gun development is being identified.

Plasma modification of starch.

PubMed

Zhu, Fan

2017-10-01

Plasma is a medium of unbound negative and positive particles with the overall electrical charge being roughly zero. Non-thermal plasma processing is an emerging green technology with great potential to improve the quality and microbial safety of various food materials. Starch is a major component of many food products and is an important ingredient for food and other industries. There has been increasing interest in utilizing plasma to modify the functionalities of starch through interactions with reactive species. This mini-review summarises the impact of plasma on composition, chemical and granular structures, physicochemical properties, and uses of starch. Structure-function relationships of starch components as affected by plasma modifications are discussed. Effect of plasma on the properties of wheat flour, which is a typical example of starch based complex food systems, is also reviewed. Future research directions on how to better utilise plasma to improve the functionalities of starch are suggested. Copyright © 2017 Elsevier Ltd. All rights reserved.

The Voronoi spatio-temporal data structure

NASA Astrophysics Data System (ADS)

Mioc, Darka

2002-04-01

Current GIS models cannot integrate the temporal dimension of spatial data easily. Indeed, current GISs do not support incremental (local) addition and deletion of spatial objects, and they can not support the temporal evolution of spatial data. Spatio-temporal facilities would be very useful in many GIS applications: harvesting and forest planning, cadastre, urban and regional planning, and emergency planning. The spatio-temporal model that can overcome these problems is based on a topological model---the Voronoi data structure. Voronoi diagrams are irregular tessellations of space, that adapt to spatial objects and therefore they are a synthesis of raster and vector spatial data models. The main advantage of the Voronoi data structure is its local and sequential map updates, which allows us to automatically record each event and performed map updates within the system. These map updates are executed through map construction commands that are composed of atomic actions (geometric algorithms for addition, deletion, and motion of spatial objects) on the dynamic Voronoi data structure. The formalization of map commands led to the development of a spatial language comprising a set of atomic operations or constructs on spatial primitives (points and lines), powerful enough to define the complex operations. This resulted in a new formal model for spatio-temporal change representation, where each update is uniquely characterized by the numbers of newly created and inactivated Voronoi regions. This is used for the extension of the model towards the hierarchical Voronoi data structure. In this model, spatio-temporal changes induced by map updates are preserved in a hierarchical data structure that combines events and corresponding changes in topology. This hierarchical Voronoi data structure has an implicit time ordering of events visible through changes in topology, and it is equivalent to an event structure that can support temporal data without precise temporal information. This formal model of spatio-temporal change representation is currently applied to retroactive map updates and visualization of map evolution. It offers new possibilities in the domains of temporal GIS, transaction processing, spatio-temporal queries, spatio-temporal analysis, map animation and map visualization.

Fluid theory and simulations of instabilities, turbulent transport and coherent structures in partially-magnetized plasmas of \\mathbf{E}\\times \\mathbf{B} discharges

NASA Astrophysics Data System (ADS)

Smolyakov, A. I.; Chapurin, O.; Frias, W.; Koshkarov, O.; Romadanov, I.; Tang, T.; Umansky, M.; Raitses, Y.; Kaganovich, I. D.; Lakhin, V. P.

2017-01-01

Partially-magnetized plasmas with magnetized electrons and non-magnetized ions are common in Hall thrusters for electric propulsion and magnetron material processing devices. These plasmas are usually in strongly non-equilibrium state due to presence of crossed electric and magnetic fields, inhomogeneities of plasma density, temperature, magnetic field and beams of accelerated ions. Free energy from these sources make such plasmas prone to various instabilities resulting in turbulence, anomalous transport, and appearance of coherent structures as found in experiments. This paper provides an overview of instabilities that exist in such plasmas. A nonlinear fluid model has been developed for description of the Simon-Hoh, lower-hybrid and ion-sound instabilities. The model also incorporates electron gyroviscosity describing the effects of finite electron temperature. The nonlinear fluid model has been implemented in the BOUT++ framework. The results of nonlinear simulations are presented demonstrating turbulence, anomalous current and tendency toward the formation of coherent structures.

Evaluation of Turner relaxed state as a model of long-lived ion-trapping structures in plasma focus and Z-pinches

NASA Astrophysics Data System (ADS)

Auluck, S. K. H.

2011-03-01

Relatively long-lived spheroidal structures coincident with the neutron emission phase have been observed in frozen deuterium fiber Z-pinch and some plasma focus devices. Existence of energetic ion-trapping mechanism in plasma focus has also been inferred from experimental data. It has been conjectured that these are related phenomena. This paper applies Turner's theory [L. Turner, IEEE Trans. Plasma Sci. 14, 849 (1986)] of relaxation of a Hall magnetofluid to construct a model of these structures and ion-trapping mechanism. Turner's solution modified for a finite-length plasma is used to obtain expressions for the magnetic field, velocity, and equilibrium pressure fields and is shown to represent an entity which is simultaneously a fluid vortex, a force-free magnetic field, a confined finite-pressure plasma, a charged object, and a trapped energetic ion beam. Characteristic features expected from diagnostic experiments are evaluated and shown to resemble experimental observations.

Study of the Role of Vortex Annihilation in the Mechanism of Neutron and X-Ray Production in the Plasma Focus.

DTIC Science & Technology

This paper shows that an understanding of the nature of the x-ray and neutron producing processes in the plasma focus requires a study of the ’fine...structure’ of the plasma focus and that this fine structure study requires diagnostic techniques with spacial resolution down to 50 micrometers and

Impact of low-pressure glow-discharge-pulsed plasma polymerization on properties of polyaniline thin films

NASA Astrophysics Data System (ADS)

Jatratkar, Aviraj A.; Yadav, Jyotiprakash B.; Deshmukh, R. R.; Barshilia, Harish C.; Puri, Vijaya; Puri, R. K.

2016-12-01

This study reports on polyaniline thin films deposited on a glass substrate using a low-pressure glow-discharge-pulsed plasma polymerization method. The polyaniline thin film obtained by pulsed plasma polymerization has been successfully demonstrated as an optical waveguide with a transmission loss of 3.93 dB cm-1, and has the potential to be employed in integrated optics. An attempt has been made to investigate the effect of plasma OFF-time on the structural, optical as well as surface properties of polyaniline thin film. The plasma ON-time has been kept constant and the plasma OFF-time has been varied throughout the work. The plasma OFF-time strongly influenced the properties of the polyaniline thin film, and a nanostructured and compact surface was revealed in the morphological studies. The plasma OFF-time was found to enhance film thickness, roughness, refractive index and optical transmission loss, whereas it reduced the optical band gap of the polyaniline thin films. Retention in the aromatic structure was confirmed by FTIR results. Optical studies revealed a π-π* electronic transition at about 317 nm as well as the formation of a branched structure. As compared with continuous wave plasma, pulsed plasma polymerization shows better properties. Pulsed plasma polymerization reduced the roughness of the film from 1.2 nm to 0.42 nm and the optical transmission loss from 6.56 dB cm-1 to 3.39 dB cm-1.

Design, Analysis and R&D of the EAST In-Vessel Components

NASA Astrophysics Data System (ADS)

Yao, Damao; Bao, Liman; Li, Jiangang; Song, Yuntao; Chen, Wenge; Du, Shijun; Hu, Qingsheng; Wei, Jing; Xie, Han; Liu, Xufeng; Cao, Lei; Zhou, Zibo; Chen, Junling; Mao, Xinqiao; Wang, Shengming; Zhu, Ning; Weng, Peide; Wan, Yuanxi

2008-06-01

In-vessel components are important parts of the EAST superconducting tokamak. They include the plasma facing components, passive plates, cryo-pumps, in-vessel coils, etc. The structural design, analysis and related R&D have been completed. The divertor is designed in an up-down symmetric configuration to accommodate both double null and single null plasma operation. Passive plates are used for plasma movement control. In-vessel coils are used for the active control of plasma vertical movements. Each cryo-pump can provide an approximately 45 m3/s pumping rate at a pressure of 10-1 Pa for particle exhaust. Analysis shows that, when a plasma current of 1 MA disrupts in 3 ms, the EM loads caused by the eddy current and the halo current in a vertical displacement event (VDE) will not generate an unacceptable stress on the divertor structure. The bolted divertor thermal structure with an active cooling system can sustain a load of 2 MW/m2 up to a 60 s operation if the plasma facing surface temperature is limited to 1500 °C. Thermal testing and structural optimization testing were conducted to demonstrate the analysis results.

Area of Stochastic Scrape-Off Layer for a Single-Null Divertor Tokamak Using Simple Map

NASA Astrophysics Data System (ADS)

Fisher, Tiffany; Verma, Arun; Punjabi, Alkesh

1996-11-01

The magnetic topology of a single-null divertor tokamak is represented by Simple Map (Punjabi A, Verma A and Boozer A, Phys Rev Lett), 69, 3322 (1992) and J Plasma Phys, 52, 91 (1994). The Simple map is characterized by a single parameter k representing the toroidal asymmetry. The width of the stochastic scrape-off layer and its area varies with the map parameter k. We calculate the area of the stochastic scrape-off layer for different k's and obtain a parametric expression for the area in terms of k and y _LastGoodSurface(k). This work is supported by US DOE OFES. Tiffany Fisher is a HU CFRT Summer Fusion High school Workshop Scholar from New Bern High School in North Carolina. She is supported by NASA SHARP Plus Program.

High Adjustable Shear Map for a Single-null Divertor Tokamak

NASA Astrophysics Data System (ADS)

Whitten, Michaelangelo; Lam, Maria; Punjabi, Alkesh

1996-11-01

An explicit map that has an adjustable shear s is x1 = x0 - k y0 [ ( 1 - y0 ) ( 1 + s y0 ) + s x ^21 ] y1 = y0 + k x1 [ 1 + s ( x^21 + y^20 ) ] Tokamak shear corresponds to negative s. Thus we can construct maps for variable shear for a single-null divertor tokamak (Punjabi A, Verma A and Boozer A, Phys Rev Lett), 3322, 69 (1992) ^, (Punjabi A, Verma A and Boozer A, J Plasma Phys), 52, 91 (1994). Here we present the results from an initial study of this map. This work is supported by US DOE OFES. Michelangelo Whitten is a HU CFRT Summer Fusion High School Workshop scholar from Bowie High School in El Paso, Texas. He is supported by NASA SHARP Plus Program.

[Effects of electroacupuncture on bispectral index and plasma beta-endorphin in patients undergoing colonoscopy].

PubMed

Ni, Yu-Fei; Li, Jun; Wang, Ben-Fu; Jiang, Song-He; Chen, Yi; Zhang, Wei-Feng; Lian, Qing-Quan

2009-10-01

To observe the effect of electroacupuncture (EA) on bispectral index (BIS) and plasma beta-endorphin (beta-EP) level in patients undergoing colonoscopy. Sixty patients were equally randomized into EA group and control group with 30 cases in each. EA (2 Hz/100 Hz, 4-6 V) was applied to the right Zusanli (ST 36) and Shangjuxu (ST 37), and the left Yinlingquan (SP 9), Sanyinjiao (SP 6) and bilateral Hegu (LI 4) respectively 30 min before colonoscopy. The mean arterial pressure (MAP), heart rate (HR) and BIS in two groups were continuously monitored during the study. Plasma beta-EP concentration was detected by radioimmunoassay. The patient's adverse reactions (including pain, satisfaction degree, etc.) were evaluated by visual analog scale (VAS) and verbal stress scale (VSS). Self-comparison showed that MAP and HR in control group increased significantly during colonoscope's splenic flexure passing (P<0.05). Whereas the 2 indexes in EA group had no significant changes during colonoscope insertion, and its splenic flexure passing, hepatic flexure passing and post-enteroscopy (P>0.05). Comparison between two groups showed that MAP at the time-point of colonoscope insertion, and HR at the time-point of colonoscope's splenic flexure passing in EA group were significantly lower than those in control group (P<0.05). BIS values of EA group were significantly lower than those of control group at different time-points after colonoscope insertion (P<0.01). Plasma beta-EP concentrations at the time-points of colonoscope's hepatic flexure passing and post-enteroscopy were evidently increased in both groups in comparison with pre-enteroscopy (P<0.01), and beta-EP was significantly lower in EA group than that in control group at the time-point of colonoscope's hepatic flexure passing (P<0.05). The dosage of Midazolam used for conscious-sedation and the scores of VAS and VSS were also considerably lower in EA group than those in control group (P<0.05, P<0.01). No significant differences were found between two groups in the adverse reactions as dizziness, nausea, vomiting and abdominal pain, but the patients' satisfaction degree in EA group was evidently higher than that in control group (P<0.05). Acupuncture analgesia can effectively lower the colonoscopy patients' BIS value and plasma beta-EP level, meaning attenuation of the patients' stress responses during colonoscopy after EA.

Statistical study of phase relationships between magnetic and plasma thermal pressures in the near-earth magnetosphere using the THEMIS satellites

NASA Astrophysics Data System (ADS)

Nishi, K.; Kazuo, S.

2017-12-01

The auroral finger-like structures appear in the equatorward part of the auroral oval in the diffuse auroral region, and contribute to the auroral fragmentation into patches during substorm recovery phase. In our previous presentations, we reported the first conjugate observation of auroral finger-like structures using the THEMIS GBO cameras and the THEMIS satellites, which was located at a radial distance of 9 Re in the dawnside plasma sheet. In this conjugate event, we found anti-phase fluctuation of plasma pressure and magnetic pressure with a time scale of 5-20 min in the plasma sheet. This observational fact is consistent with the idea that the finger-like structures are caused by a pressure-driven instability in the balance of plasma and magnetic pressures in the magnetosphere. Then we also searched simultaneous observation events of auroral finger-like structures with the RBSP satellites which have an apogee of 5.8 Re in the inner magnetosphere. Contrary to the first result, the observed variation of plasma and magnetic pressures do not show systematic phase relationship. In order to investigate these phase relationships between plasma and magnetic pressures in the magnetosphere, we statistically analyzed these pressure data using the THEMIS-E satellite for one year in 2011. In the preliminary analysis of pressure variation spectra, we found that out of phase relationship between magnetic and plasma pressures occupied 40 % of the entire period of study. In the presentation, we will discuss these results in the context of relationships between the pressure fluctuations and the magnetospheric instabilities that can cause auroral finger-like structures.

Nonlinear low frequency electrostatic structures in a magnetized two-component auroral plasma

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

Rufai, O. R., E-mail: rajirufai@gmail.com; Scientific Computing, Memorial University of Newfoundland, St John's, Newfoundland and Labrador A1C 5S7; Bharuthram, R., E-mail: rbharuthram@uwc.ac.za

2016-03-15

Finite amplitude nonlinear ion-acoustic solitons, double layers, and supersolitons in a magnetized two-component plasma composed of adiabatic warm ions fluid and energetic nonthermal electrons are studied by employing the Sagdeev pseudopotential technique and assuming the charge neutrality condition at equilibrium. The model generates supersoliton structures at supersonic Mach numbers regime in addition to solitons and double layers, whereas in the unmagnetized two-component plasma case only, soliton and double layer solutions can be obtained. Further investigation revealed that wave obliqueness plays a critical role for the evolution of supersoliton structures in magnetized two-component plasmas. In addition, the effect of ion temperaturemore » and nonthermal energetic electron tends to decrease the speed of oscillation of the nonlinear electrostatic structures. The present theoretical results are compared with Viking satellite observations.« less

Analysis of Helimak Plasma Using Movies of Density Contours

NASA Astrophysics Data System (ADS)

Williams, Chad; Gentle, Kenneth; Li, Bo

2013-10-01

Using an array of Langmuir probes we have created two-dimensional contour plot movies showing the arrangement, convection, and time sequence of plasma structures inside of the Texas Helimak, which approximates aspects of the tokamak SOL. These structures are seen to vary with time, magnetic field line pitch, and applied bias voltage. The probes are distributed in two sets of 48 probes arranged in a grid with two centimeter spacing, providing good spatial resolution of these structures. We find that, for negative biases, the plasma moves away from the biased plate in agreement with the simulations. For positive biases, the plasma is found close to the bias plate. Positive biases are seen to induce more radial convection than the negatively biased case. While all structures vary with time, those at lower magnetic field line pitch are seen to vary most dramatically.

Experimental Characterization of Plasma Detachment from Magnetic Nozzles

NASA Astrophysics Data System (ADS)

Olsen, Christopher Scott

Magnetic nozzles, like Laval nozzles, are observed in several natural systems and have application in areas such as electric propulsion and plasma processing. Plasma flowing through these nozzles is inherently tied to the field lines and must separate for momentum redirection or particle transport to occur. Plasma detachment and associated mechanisms from a magnetic nozzle are investigated. Experimental results are presented from the plume of the VASIMRRTM VX-200 device flowing along an axisymmetric magnetic nozzle and operated at two ion energies to explore momentum dependent detachment. The argon plume expanded into a 150m3 vacuum chamber where the background pressure was low enough that charge-exchange mean-free-paths were longer than experiment scale lengths. This magnetic nozzle system is demonstrated to hydrodynamically scale up to astrophysical plasmas, particularly the solar chromosphere, implying general relevance to many systems. Plasma parameters were mapped over a large spatial range using measurements from multiple plasma diagnostics. The data show that the plume does not follow the magnetic field lines. A mapped integration of the ion flux shows the plume may be divided into three regions where 1) the plume briefly follows the magnetic flux, 2) diverges quadratically before 3) expanding with linear trajectories. Transitioning from region 1→2, the ion flux departs from the magnetic flux suggesting ion detachment. An instability forms in region 2 driving an oscillating electric field that causes ions to expand before enhancing electron cross-field transport through anomalous resistivity. Transitioning from region 2→3 the electric field dissipates, the trajectories linearize, and the plume effectively detaches. A delineation of sub-to-super Alfvenic flow aligns well with the inflection points of the linearization without a change in magnetic topology. The detachment process is best described as a two part process: First, ions detach by a breakdown of the magnetic moment when the quantity |v/fcLB| becomes of order unity. Second, the turbulent electric field enhances electron transport up to a factor of 4+/-1 above collisional diffusion; electron cross-field velocities approximate that of the ions and depart on more centralized field lines. Electrons are believed to detach by breakdown of magnetic moment further downstream in the weaker magnetic field.

Brain-mapping projects using the common marmoset.

PubMed

Okano, Hideyuki; Mitra, Partha

2015-04-01

Globally, there is an increasing interest in brain-mapping projects, including the Brain Research through Advancing Innovative Neurotechnologies (BRAIN) Initiative project in the USA, the Human Brain Project (HBP) in Europe, and the Brain Mapping by Integrated Neurotechnologies for Disease Studies (Brain/MINDS) project in Japan. These projects aim to map the structure and function of neuronal circuits to ultimately understand the vast complexity of the human brain. Brain/MINDS is focused on structural and functional mapping of the common marmoset (Callithrix jacchus) brain. This non-human primate has numerous advantages for brain mapping, including a well-developed frontal cortex and a compact brain size, as well as the availability of transgenic technologies. In the present review article, we discuss strategies for structural and functional mapping of the marmoset brain and the relation of the common marmoset to other animals models. Copyright © 2014 The Authors. Published by Elsevier Ireland Ltd.. All rights reserved.

Serotonin involvement in pituitary-adrenal function

NASA Technical Reports Server (NTRS)

Vernikos-Danellis, J.; Kellar, K. J.; Kent, D.; Gonzales, C.; Berger, P. A.; Barchas, J. D.

1977-01-01

Experiments clarifying the effects of serotonin (5-HT) in the regulation of the hypothalamic-pituitary-adrenocortical system are surveyed. Lesion experiments which seek to determine functional maps of serotonergic input to areas involved in regulation are reported. Investigations of the effects of 5-HT levels on the plasma ACTH response to stress and the diurnal variation in basal plasma corticosterone are summarized, and the question of whether serotonergic transmission is involved in the regulation of all aspects of pituitary-adrenal function is considered with attention to the stimulatory and inhibitory action of 5-HT.

New type of chimera and mutual synchronization of spatiotemporal structures in two coupled ensembles of nonlocally interacting chaotic maps

NASA Astrophysics Data System (ADS)

Bukh, Andrei; Rybalova, Elena; Semenova, Nadezhda; Strelkova, Galina; Anishchenko, Vadim

2017-11-01

We study numerically the dynamics of a network made of two coupled one-dimensional ensembles of discrete-time systems. The first ensemble is represented by a ring of nonlocally coupled Henon maps and the second one by a ring of nonlocally coupled Lozi maps. We find that the network of coupled ensembles can realize all the spatio-temporal structures which are observed both in the Henon map ensemble and in the Lozi map ensemble while uncoupled. Moreover, we reveal a new type of spatiotemporal structure, a solitary state chimera, in the considered network. We also establish and describe the effect of mutual synchronization of various complex spatiotemporal patterns in the system of two coupled ensembles of Henon and Lozi maps.

Evolution of Magnetic Rayleigh–Taylor Instability into the Outer Solar Corona and Low Interplanetary Space

NASA Astrophysics Data System (ADS)

Mishra, Sudheer K.; Singh, Talwinder; Kayshap, P.; Srivastava, A. K.

2018-03-01

We analyze the observations from Solar TErrestrial RElations Observatory (STEREO)-A and B/COR-1 of an eruptive prominence in the intermediate corona on 2011 June 7 at 08:45 UT, which consists of magnetic Rayleigh–Taylor (MRT) unstable plasma segments. Its upper-northward segment shows spatio-temporal evolution of MRT instability in form of finger structures up to the outer corona and low interplanetary space. Using the method of Dolei et al., It is estimated that the density in each bright finger is greater than the corresponding dark region lying below it in the surrounding intermediate corona. The instability is evolved due to wave perturbations that are parallel to the magnetic field at the density interface. We conjecture that the prominence plasma is supported by tension component of the magnetic field against gravity. Through the use of linear stability theory, the magnetic field is estimated as 21–40 mG to suppress growth of MRT instability in the observed finger structures. In the southward plasma segment, a horn-like structure is observed at 11:55 UT in the intermediate corona that also indicates MRT instability. Falling blobs are also observed in both of the plasma segments. In the outer corona, up to 6–13 solar radii, the mushroom-like plasma structures have been identified in the upper-northward MRT unstable plasma segment using STEREO-A/COR-2. These structures most likely grew due to the breaking and twisting of fingers at large spatial scales in weaker magnetic fields. In the lower interplanetary space up to 20 solar radii, these structures are fragmented into various small-scale localized plasma spikes, most likely due to turbulent mixing.

Double layers and double wells in arbitrary degenerate plasmas

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

Akbari-Moghanjoughi, M.

Using the generalized hydrodynamic model, the possibility of variety of large amplitude nonlinear excitations is examined in electron-ion plasma with arbitrary electron degeneracy considering also the ion temperature effect. A new energy-density relation is proposed for plasmas with arbitrary electron degeneracy which reduces to the classical Boltzmann and quantum Thomas-Fermi counterparts in the extreme limits. The pseudopotential method is employed to find the criteria for existence of nonlinear structures such as solitons, periodic nonlinear structures, and double-layers for different cases of adiabatic and isothermal ion fluids for a whole range of normalized electron chemical potential, η{sub 0}, ranging from dilutemore » classical to completely degenerate electron fluids. It is observed that there is a Mach-speed gap in which no large amplitude localized or periodic nonlinear excitations can propagate in the plasma under consideration. It is further revealed that the plasma under investigation supports propagation of double-wells and double-layers the chemical potential and Mach number ranges of which are studied in terms of other plasma parameters. The Mach number criteria for nonlinear waves are shown to significantly differ for cases of classical with η{sub 0} < 0 and quantum with η{sub 0} > 0 regimes. It is also shown that the localized structure propagation criteria possess significant dissimilarities for plasmas with adiabatic and isothermal ions. Current research may be generalized to study the nonlinear structures in plasma containing positrons, multiple ions with different charge states, and charged dust grains.« less

Simulations of Atmospheric Plasma Arcs

NASA Astrophysics Data System (ADS)

Pearcy, Jacob; Chopra, Nirbhav; Jaworski, Michael

2017-10-01

We present the results of computer simulation of cylindrical plasma arcs with characteristics similar to those predicted to be relevant in magnetohydrodynamic (MHD) power conversion systems. These arcs, with core temperatures on the order of 1 eV, place stringent limitations on the lifetime of conventional electrodes used in such systems, suggesting that a detailed analysis of arc characteristics will be crucial in designing more robust electrode systems. Simulations utilize results from NASA's Chemical Equilibrium with Applications (CEA) program to solve the Elenbaas-Heller equation in a variety of plasma compositions, including approximations of coal-burning plasmas as well as pure gas discharges. The effect of carbon dioxide injection on arc characteristics, emulating discharges from molten carbonate salt electrodes, is also analyzed. Results include radial temperature profiles, composition maps, and current-voltage (IV) characteristics of these arcs. Work supported by DOE contract DE-AC02-09CH11466.

Tools for phospho- and glycoproteomics of plasma membranes.

PubMed

Wiśniewski, Jacek R

2011-07-01

Analysis of plasma membrane proteins and their posttranslational modifications is considered as important for identification of disease markers and targets for drug treatment. Due to their insolubility in water, studying of plasma membrane proteins using mass spectrometry has been difficult for a long time. Recent technological developments in sample preparation together with important improvements in mass spectrometric analysis have facilitated analysis of these proteins and their posttranslational modifications. Now, large scale proteomic analyses allow identification of thousands of membrane proteins from minute amounts of sample. Optimized protocols for affinity enrichment of phosphorylated and glycosylated peptides have set new dimensions in the depth of characterization of these posttranslational modifications of plasma membrane proteins. Here, I summarize recent advances in proteomic technology for the characterization of the cell surface proteins and their modifications. In the focus are approaches allowing large scale mapping rather than analytical methods suitable for studying individual proteins or non-complex mixtures.

Growth of vertically aligned carbon nanofibers by low-pressure inductively coupled plasma-enhanced chemical vapor deposition

NASA Astrophysics Data System (ADS)

Caughman, J. B. O.; Baylor, L. R.; Guillorn, M. A.; Merkulov, V. I.; Lowndes, D. H.; Allard, L. F.

2003-08-01

Vertically aligned carbon nanofibers (VACNFs) have been grown using a low-pressure, plasma-enhanced, chemical vapor deposition process. The nanofibers are grown from a nickel catalyst that can be patterned to form arrays of individual, isolated VACNFs. The fibers are grown at pressures below 100 mTorr, using an inductively coupled plasma source with a radio-frequency bias on the sample substrate to allow for independent control of the ion energies. Plasma conditions are related to growth results by comparing optical emission from the plasma to the physical structure of the nanofibers. We find that the ratio of etching species in the plasma to depositing species is critical to the final shape of the carbon structures that are formed.

Plasma Liner Development for MTF Applications: A Status Report

NASA Technical Reports Server (NTRS)

Eskridge, R. E.; Thio, Y. F.; Lee, M.; Martin, A.; Smith, J. W.; Griffin, S. T.; Schafer, Charles (Technical Monitor)

2001-01-01

An experimental plasma gun for Magnetic Target Fusion (MTF) applications under development at the NASA Marshall Space Flight Center is described. This gun has been tested experimentally and plasma jet velocities of approximately 50 km/sec have been obtained. The plasma jet structure has been photographed with 10 ns exposure times to reveal a stable and repeatable plasma structure. Data for velocity profile information has been obtained using light pipes embedded in the gun walls to record the plasma transit at various barrel locations. A high speed triggering system has been developed and tested as a means of reducing the gun "jitter". This jitter has been characterized and future work for second generation "ultra-low jitter" gun development is identified.

Atmospheric-Pressure Plasma Interaction with Soft Materials as Fundamental Processes in Plasma Medicine.

PubMed

Takenaka, Kosuke; Miyazaki, Atsushi; Uchida, Giichiro; Setsuhara, Yuichi

2015-03-01

Molecular-structure variation of organic materials irradiated with atmospheric pressure He plasma jet have been investigated. Optical emission spectrum in the atmospheric-pressure He plasma jet has been measured. The spectrum shows considerable emissions of He lines, and the emission of O and N radicals attributed to air. Variation in molecular structure of Polyethylene terephthalate (PET) film surface irradiated with the atmospheric-pressure He plasma jet has been observed via X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FT-IR). These results via XPS and FT-IR indicate that the PET surface irradiated with the atmospheric-pressure He plasma jet was oxidized by chemical and/or physical effect due to irradiation of active species.

GEOMETRY AND CHARACTERISTICS OF THE HELIOSHEATH REVEALED IN THE FIRST FIVE YEARS OF INTERSTELLAR BOUNDARY EXPLORER OBSERVATIONS

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

Zirnstein, E. J.; McComas, D. J.; Schwadron, N. A.

2016-07-20

We investigate and interpret the geometry and characteristics of the inner heliosheath (IHS) plasma and their impact on the heliotail structure as observed in energetic neutral atom (ENA) maps acquired during the first 5 yr of Interstellar Boundary Explorer ( IBEX ) observations. In particular, IBEX observations of the heliotail reveal distinct, localized emission features (lobes) that provide a rich set of information about the properties and evolution of the heliosheath plasma downstream of the termination shock (TS). We analyze the geometry of the heliotail lobes and find that the plane intersecting the port and starboard heliotail lobe centers ismore » ∼6° from the solar equatorial plane, and the plane intersecting the north and south heliotail lobe centers is ∼90° from the solar equatorial plane, both indicating strong correlation with the fast–slow solar wind asymmetry, and thus reflecting the structure of the IHS flow around the Sun. We also analyze the key parameters and processes that form and shape the port and starboard lobes, which are distinctly different from the north and south lobes. By comparing IBEX ENA observations with results from a simplistic flow model of the heliosphere and a multicomponent description for pickup ions (PUIs) in the IHS, we find that the port and starboard lobe formation is driven by a thin IHS, large nose–tail asymmetry of the distance to the TS (and consequently, a large nose–tail asymmetry of the relative abundance of PUIs at the TS) and the energy-dependent removal of PUIs by charge exchange in the IHS.« less

Climatology of successive equatorial plasma bubbles observed by GPS ROTI over Malaysia

NASA Astrophysics Data System (ADS)

Buhari, S. M.; Abdullah, M.; Yokoyama, T.; Otsuka, Y.; Nishioka, M.; Hasbi, A. M.; Bahari, S. A.; Tsugawa, T.

2017-02-01

The occurrence rate of the equatorial plasma bubble (EPB) with season, solar activity, and geomagnetic conditions are investigated using long-term data sets of Malaysia Real-Time Kinematics Network (MyRTKnet) from 2008 to 2013. The rate of TEC (total electron content) change index (ROTI) in 5 min was derived from MyRTKnet data to detect the EPB with scale sizes around tens of kilometers. Then, the daily east-west cross sections of 2-D ROTI maps were used to examine the EPB features over 100°E-119°E longitudes. The EPBs tend to occur successively in one night along the observational coverage of MyRTKnet during equinoxes in high solar activity years. The perturbations in a form of wavelike structures along the observed longitudes might be responsible for the development of successive EPBs due to high growth rate of the Rayleigh-Taylor instability (RTI) process. On the contrary, the occurrence of successive EPBs is infrequent and the occurrence day of EPB remains active during equinoctial months in low solar activity years. The small growth rate of the RTI process during low solar activity years might require a strong seed perturbation to generate the EPB structure. The occurrence probability of the EPB was found to be similar during quiet and disturbed geomagnetic conditions. The results imply that the strong perturbations play an important role in the development of the EPB in low solar activity years. Nonetheless, the high growth rate of the RTI could cause the successive occurrence of the EPB in high solar activity years.

Finite Beta Boundary Magnetic Fields of NCSX

NASA Astrophysics Data System (ADS)

Grossman, A.; Kaiser, T.; Mioduszewski, P.

2004-11-01

The magnetic field between the plasma surface and wall of the National Compact Stellarator (NCSX), which uses quasi-symmetry to combine the best features of the tokamak and stellarator in a configuration of low aspect ratio is mapped via field line tracing in a range of finite beta in which part of the rotational transform is generated by the bootstrap current. We adopt the methodology developed for W7-X, in which an equilibrium solution is computed by an inverse equilibrium solver based on an energy minimizing variational moments code, VMEC2000[1], which solves directly for the shape of the flux surfaces given the external coils and their currents as well as a bootstrap current provided by a separate transport calculation. The VMEC solution and the Biot-Savart vacuum fields are coupled to the magnetic field solver for finite-beta equilibrium (MFBE2001)[2] code to determine the magnetic field on a 3D grid over a computational domain. It is found that the edge plasma is more stellarator-like, with a complex 3D structure, and less like the ordered 2D symmetric structure of a tokamak. The field lines make a transition from ergodically covering a surface to ergodically covering a volume, as the distance from the last closed magnetic surface is increased. The results are compared with the PIES[3] calculations. [1] S.P. Hirshman et al. Comput. Phys. Commun. 43 (1986) 143. [2] E. Strumberger, et al. Nucl. Fusion 42 (2002) 827. [3] A.H. Reiman and H.S. Greenside, Comput. Phys. Commun. 43, 157 (1986).

Talbot-Lau x-ray deflectometer electron density diagnostic for laser and pulsed power high energy density plasma experiments (invited).

PubMed

Valdivia, M P; Stutman, D; Stoeckl, C; Mileham, C; Begishev, I A; Theobald, W; Bromage, J; Regan, S P; Klein, S R; Muñoz-Cordovez, G; Vescovi, M; Valenzuela-Villaseca, V; Veloso, F

2016-11-01

Talbot-Lau X-ray deflectometry (TXD) has been developed as an electron density diagnostic for High Energy Density (HED) plasmas. The technique can deliver x-ray refraction, attenuation, elemental composition, and scatter information from a single Moiré image. An 8 keV Talbot-Lau interferometer was deployed using laser and x-pinch backlighters. Grating survival and electron density mapping were demonstrated for 25-29 J, 8-30 ps laser pulses using copper foil targets. Moiré pattern formation and grating survival were also observed using a copper x-pinch driven at 400 kA, ∼1 kA/ns. These results demonstrate the potential of TXD as an electron density diagnostic for HED plasmas.

Talbot-Lau X-ray Deflectometer electron density diagnostic for laser and pulsed power high energy density plasma experiments

DOE PAGES

Valdivia, M. P.; Stutman, D.; Stoeckl, C.; ...

2016-04-21

Talbot-Lau X-ray Deflectometry has been developed as an electron density diagnostic for High Energy Density plasmas. The technique can deliver x-ray refraction, attenuation, elemental composition, and scatter information from a single Moiré image. An 8 keV Talbot-Lau interferometer was deployed using laser and x-pinch backlighters. Grating survival and electron density mapping was demonstrated for 25-29 J, 8-30 ps laser pulses using copper foil targets. Moire pattern formation and grating survival was also observed using a copper x-pinch driven at 400 kA, ~1 kA/ns. Lastly, these results demonstrate the potential of TXD as an electron density diagnostic for HED plasmas.

Method and system of Jones-matrix mapping of blood plasma films with "fuzzy" analysis in differentiation of breast pathology changes

NASA Astrophysics Data System (ADS)

Zabolotna, Natalia I.; Radchenko, Kostiantyn O.; Karas, Oleksandr V.

2018-01-01

A fibroadenoma diagnosing of breast using statistical analysis (determination and analysis of statistical moments of the 1st-4th order) of the obtained polarization images of Jones matrix imaginary elements of the optically thin (attenuation coefficient τ <= 0,1 ) blood plasma films with further intellectual differentiation based on the method of "fuzzy" logic and discriminant analysis were proposed. The accuracy of the intellectual differentiation of blood plasma samples to the "norm" and "fibroadenoma" of breast was 82.7% by the method of linear discriminant analysis, and by the "fuzzy" logic method is 95.3%. The obtained results allow to confirm the potentially high level of reliability of the method of differentiation by "fuzzy" analysis.

Understanding the Effect of Gas Dynamics in Plasma Gun Performance for Simulating Fusion Wall Response to Disruption Events

NASA Astrophysics Data System (ADS)

Riedel, Will; Underwood, Thomas; Righetti, Fabio; Cappelli, Mark

2017-10-01

In this work, the suitability of a pulsed coaxial plasma accelerator to simulate the interaction of edge-localized modes with plasma first wall materials is investigated. Experimental measurements derived from a suite of diagnostics are presented that focus on both the properties of the plasma flow and the manner in which such jets couple with material interfaces. Specific emphasis is placed on quantifying the variation in these properties using tungsten tokens exposed to the plasma plume as the gun volume is progressively filled with more neutral gas. These results are mapped to the operational dynamics of the gun via a time-resolved Schlieren cinematic visualization of the density gradient within the flow. Resulting videos indicate the existence of two distinct modes with vastly different characteristic timescales, spatial evolution, and plasma properties. Time resolved quantification of the associated plasma heat flux for both modes, including a range spanning 150 MW m-2 - 10 GW m-2, is presented using both a fast thermocouple gauge and an IR camera. Both diagnostics in conjunction with a heat transfer model provide an accurate description of the energy transfer dynamics and operational characteristics of plasma guns. This work is supported by the U.S. Department of Energy Stewardship Science Academic Program.

Strategies for the generation of parametric images of [11C]PIB with plasma input functions considering discriminations and reproducibility.

PubMed

Edison, Paul; Brooks, David J; Turkheimer, Federico E; Archer, Hilary A; Hinz, Rainer

2009-11-01

Pittsburgh compound B or [11C]PIB is an amyloid imaging agent which shows a clear differentiation between subjects with Alzheimer's disease (AD) and controls. However the observed signal difference in other forms of dementia such as dementia with Lewy bodies (DLB) is smaller, and mild cognitively impaired (MCI) subjects and some healthy elderly normals may show intermediate levels of [11C]PIB binding. The cerebellum, a commonly used reference region for non-specific tracer uptake in [11C]PIB studies in AD may not be valid in Prion disorders or monogenic forms of AD. The aim of this work was to: 1-compare methods for generating parametric maps of [11C]PIB retention in tissue using a plasma input function in respect of their ability to discriminate between AD subjects and controls and 2-estimate the test-retest reproducibility in AD subjects. 12 AD subjects (5 of which underwent a repeat scan within 6 weeks) and 10 control subjects had 90 minute [11C]PIB dynamic PET scans, and arterial plasma input functions were measured. Parametric maps were generated with graphical analysis of reversible binding (Logan plot), irreversible binding (Patlak plot), and spectral analysis. Between group differentiation was calculated using Student's t-test and comparisons between different methods were made using p values. Reproducibility was assessed by intraclass correlation coefficients (ICC). We found that the 75 min value of the impulse response function showed the best group differentiation and had a higher ICC than volume of distribution maps generated from Logan and spectral analysis. Patlak analysis of [11C]PIB binding was the least reproducible.

Pharmacokinetics and electrophysiological effects of sotalol hydrochloride in horses.

PubMed

Broux, B; De Clercq, D; Decloedt, A; Vera, L; Devreese, M; Gehring, R; Croubels, S; van Loon, G

2018-05-01

Arrhythmias in horses may require long-term anti-arrhythmic therapy. Unfortunately, oral anti-arrhythmic drugs for use in horses are currently scarce. In human patients and small animals, sotalol, a β-blocker with class III anti-arrhythmic properties, is often used for long-term treatment. To determine the pharmacokinetics of sotalol at multiple oral dosages in unfasted horses, as well as the effects on electro- and echocardiographic measurements, right atrial and ventricular monophasic action potential (MAP) and effective refractory period (ERP). Placebo controlled, double-blinded experiment. Six healthy, unfasted Warmblood horses were given either 0, 2, 3 or 4 mg/kg bodyweight (bwt) sotalol orally (PO) twice daily (bid) for 9 days in a randomised cross-over design. Echocardiography and surface electrocardiography were performed and plasma concentrations of sotalol and right atrial and right ventricular MAPs and ERPs were determined at steady-state conditions. Statistical analysis was performed using a repeated measures univariate analysis with post hoc Bonferroni corrections. Calculated mean steady-state plasma concentrations determined by nonlinear mixed-effect modelling were 287 (range 234-339), 409 (359-458) and 543 (439-646) ng/mL for 2, 3 and 4 mg/kg bwt sotalol PO bid respectively. Sotalol significantly increased the QT interval and ERPs, but, despite increasing plasma concentrations, higher dosages did not result in a progressive increase in QT interval or ERPs. Echocardiographic and other electrocardiographic measurements did not change significantly. MAP durations at 90% repolarisation were not significantly different during sotalol treatment. Besides transient local sweating, no side effects were noted. Study size and ad libitum feeding of hay. Sotalol at a dose of 2, 3 and 4 mg/kg bwt PO bid increases the QT interval and ERP and might be a useful drug for long-term anti-arrhythmic therapy in horses. © 2017 EVJ Ltd.

PHYSICAL CONDITIONS OF CORONAL PLASMA AT THE TRANSIT OF A SHOCK DRIVEN BY A CORONAL MASS EJECTION

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

Susino, R.; Bemporad, A.; Mancuso, S., E-mail: susino@oato.inaf.it

2015-10-20

We report here on the determination of plasma physical parameters across a shock driven by a coronal mass ejection using white light (WL) coronagraphic images and radio dynamic spectra (RDS). The event analyzed here is the spectacular eruption that occurred on 2011 June 7, a fast CME followed by the ejection of columns of chromospheric plasma, part of them falling back to the solar surface, associated with a M2.5 flare and a type-II radio burst. Images acquired by the Solar and Heliospheric Observatory/LASCO coronagraphs (C2 and C3) were employed to track the CME-driven shock in the corona between 2–12 R{submore » ⊙} in an angular interval of about 110°. In this interval we derived two-dimensional (2D) maps of electron density, shock velocity, and shock compression ratio, and we measured the shock inclination angle with respect to the radial direction. Under plausible assumptions, these quantities were used to infer 2D maps of shock Mach number M{sub A} and strength of coronal magnetic fields at the shock's heights. We found that in the early phases (2–4 R{sub ⊙}) the whole shock surface is super-Alfvénic, while later on (i.e., higher up) it becomes super-Alfvénic only at the nose. This is in agreement with the location for the source of the observed type-II burst, as inferred from RDS combined with the shock kinematic and coronal densities derived from WL. For the first time, a coronal shock is used to derive a 2D map of the coronal magnetic field strength over intervals of 10 R{sub ⊙} altitude and ∼110° latitude.« less

Ion-acoustic and electron-acoustic type nonlinear waves in dusty plasmas

NASA Astrophysics Data System (ADS)

Volosevich, A.-V.; Meister, C.-V.

2003-04-01

In the present work, two three-dimensional nonlinear theoretical models of electrostatic solitary waves are investigated within the frame of magnetohydrodynamics. Both times, a multi-component plasma is considered, which consists of hot electrons with a rather flexible distribution function, hot ions with Boltzmann-type distribution, and (negatively as well as positively charged) dust. Additionally, cold ion beams are taken into account in the model to study ion-acoustic structures (IAS), and cold electron beams are included into the model to investigate electron-acoustic structures (EAS). The numerical results of the considered theoretical models allow to make the following conclusions: 1) Electrostatic structures with negative potential (of rarefaction type) are formed both in the IAS model and in the EAS model, but structures with negative potential (of compressional type) are formed in the IAS model only. 2) The intervals of various plasma parameters (velocities of ion and electron beams, temperatures, densities of the plasma components, ions' masses), for which the existence of IAS and EAS solitary waves and structures is possible, are calculated. 3) Further, the parameters of the electrostatic structures (wave amplitudes, scales along and perpendicular to the magnetic field, velocities) are estimated. 4) The application of the present numerical simulation for multi-component plasmas to various astrophysical systems under different physical conditions is discussed.

Plasma Structure and Behavior of Miniature Ring-Cusp Discharges

NASA Astrophysics Data System (ADS)

Mao, Hann-Shin

Miniature ring-cusp ion thrusters provide a unique blend of high efficiencies and millinewton level thrust for future spacecraft. These thrusters are attractive as a primary propulsion for small satellites that require a high delta V, and as a secondary propulsion for larger spacecraft that require precision formation flying, disturbance rejection, or attitude control. To ensure desirable performance throughout the life of such missions, an advancement in the understanding of the plasma structure and behavior of miniature ring-cusp discharges is required. A research model was fabricated to provide a simplified experimental test bed for the analysis of the plasma discharge chamber of a miniature ion thruster. The plasma source allowed for spatially resolved measurements with a Langmuir probe along a meridian plane. Probe measurements yielded plasma density, electron temperature, and plasma potential data. The magnetic field strength was varied along with the discharge current to determine the plasma behavior under various conditions. The structure of the plasma properties were found to be independent of the discharge power under the proper scaling. It was concluded that weaker magnetic fields can improve the overall performance for ion thruster operation. To further analyze the experimental measurements, a framework was developed based on the magnetic field. A flux aligned coordinate system was developed to decouple the perpendicular and parallel plasma motion with respect to the magnetic field. This was done using the stream function and magnetic scalar potential. Magnetic formulae provided intuition on the field profiles dependence on magnet dimensions. The flux aligned coordinate system showed that the plasma was isopycnic along constant stream function values. This was used to develop an empirical relation suitable for estimating the spatial behavior and to determine the plasma volume and loss areas. The plasma geometry estimates were applied to a control volume analysis on the plasma electrons. Balancing the plasma electron generation and loss yielded nominal values used in miniature ion thrusters. This result was ultimately used to develop a design tool for miniature discharges. This tool was used to perform a parametric evaluation on the magnet field configuration of the research mode. By understanding the plasma behavior, significant improvements over the baseline configuration were obtained with relatively minor changes, thus revealing the importance of plasma structure on the performance of miniature ring-cusp discharges.

Magnetic evaluation of hydrogen pressures changes on MHD fluctuations in IR-T1 tokamak plasma

NASA Astrophysics Data System (ADS)

Alipour, Ramin; Ghanbari, Mohamad R.

2018-04-01

Identification of tokamak plasma parameters and investigation on the effects of each parameter on the plasma characteristics is important for the better understanding of magnetohydrodynamic (MHD) activities in the tokamak plasma. The effect of different hydrogen pressures of 1.9, 2.5 and 2.9 Torr on MHD fluctuations of the IR-T1 tokamak plasma was investigated by using of 12 Mirnov coils, singular value decomposition and wavelet analysis. The parameters such as plasma current, loop voltage, power spectrum density, energy percent of poloidal modes, dominant spatial structures and temporal structures of poloidal modes at different plasma pressures are plotted. The results indicate that the MHD activities at the pressure of 2.5 Torr are less than them at other pressures. It also has been shown that in the stable area of plasma and at the pressure of 2.5 Torr, the magnetic force and the force of plasma pressure are in balance with each other and the MHD activities are at their lowest level.

Functional materials discovery using energy-structure-function maps

NASA Astrophysics Data System (ADS)

Pulido, Angeles; Chen, Linjiang; Kaczorowski, Tomasz; Holden, Daniel; Little, Marc A.; Chong, Samantha Y.; Slater, Benjamin J.; McMahon, David P.; Bonillo, Baltasar; Stackhouse, Chloe J.; Stephenson, Andrew; Kane, Christopher M.; Clowes, Rob; Hasell, Tom; Cooper, Andrew I.; Day, Graeme M.

2017-03-01

Molecular crystals cannot be designed in the same manner as macroscopic objects, because they do not assemble according to simple, intuitive rules. Their structures result from the balance of many weak interactions, rather than from the strong and predictable bonding patterns found in metal-organic frameworks and covalent organic frameworks. Hence, design strategies that assume a topology or other structural blueprint will often fail. Here we combine computational crystal structure prediction and property prediction to build energy-structure-function maps that describe the possible structures and properties that are available to a candidate molecule. Using these maps, we identify a highly porous solid, which has the lowest density reported for a molecular crystal so far. Both the structure of the crystal and its physical properties, such as methane storage capacity and guest-molecule selectivity, are predicted using the molecular structure as the only input. More generally, energy-structure-function maps could be used to guide the experimental discovery of materials with any target function that can be calculated from predicted crystal structures, such as electronic structure or mechanical properties.

Functional materials discovery using energy-structure-function maps.

PubMed

Pulido, Angeles; Chen, Linjiang; Kaczorowski, Tomasz; Holden, Daniel; Little, Marc A; Chong, Samantha Y; Slater, Benjamin J; McMahon, David P; Bonillo, Baltasar; Stackhouse, Chloe J; Stephenson, Andrew; Kane, Christopher M; Clowes, Rob; Hasell, Tom; Cooper, Andrew I; Day, Graeme M

2017-03-30

Molecular crystals cannot be designed in the same manner as macroscopic objects, because they do not assemble according to simple, intuitive rules. Their structures result from the balance of many weak interactions, rather than from the strong and predictable bonding patterns found in metal-organic frameworks and covalent organic frameworks. Hence, design strategies that assume a topology or other structural blueprint will often fail. Here we combine computational crystal structure prediction and property prediction to build energy-structure-function maps that describe the possible structures and properties that are available to a candidate molecule. Using these maps, we identify a highly porous solid, which has the lowest density reported for a molecular crystal so far. Both the structure of the crystal and its physical properties, such as methane storage capacity and guest-molecule selectivity, are predicted using the molecular structure as the only input. More generally, energy-structure-function maps could be used to guide the experimental discovery of materials with any target function that can be calculated from predicted crystal structures, such as electronic structure or mechanical properties.

Diagnostics of microwave assisted electron cyclotron resonance plasma source for surface modification of nylon 6

NASA Astrophysics Data System (ADS)

More, Supriya E.; Das, Partha Sarathi; Bansode, Avinash; Dhamale, Gayatri; Ghorui, S.; Bhoraskar, S. V.; Sahasrabudhe, S. N.; Mathe, Vikas L.

2018-01-01

Looking at the increasing scope of plasma processing of materials surface, here we present the development and diagnostics of a microwave assisted Electron Cyclotron Resonance (ECR) plasma system suitable for surface modification of polymers. Prior to the surface-treatment, a detailed diagnostic mapping of the plasma parameters throughout the reactor chamber was carried out by using single and double Langmuir probe measurements in Ar plasma. Conventional analysis of I-V curves as well as the elucidation form of the Electron Energy Distribution Function (EEDF) has become the source of calibration of plasma parameters in the reaction chamber. The high energy tail in the EEDF of electron temperature is seen to extend beyond 60 eV, at much larger distances from the ECR zone. This proves the suitability of the rector for plasma processing, since the electron energy is much beyond the threshold energy of bond breaking in most of the polymers. Nylon 6 is used as a representative candidate for surface processing in the presence of Ar, H2 + N2, and O2 plasma, treated at different locations inside the plasma chamber. In a typical case, the work of adhesion is seen to almost get doubled when treated with oxygen plasma. Morphology of the plasma treated surface and its hydrophilicity are discussed in view of the variation in electron density and electron temperature at these locations. Nano-protrusions arising from plasma treatment are set to be responsible for the hydrophobicity. Chemical sputtering and physical sputtering are seen to influence the surface morphology on account of sufficient electron energies and increased plasma potential.

An Experimental Study of a Low-Jitter Pulsed Electromagnetic Plasma Accelerator

NASA Technical Reports Server (NTRS)

Thio, Y. C. Francis; Lee, Michael; Eskridge, Richard; Smith, James; Martin, Adam; Rodgers, Stephen L. (Technical Monitor)

2001-01-01

An experimental plasma accelerator for a variety of applications under development at the NASA Marshall Space Flight Center is described. The accelerator is a pulsed plasma thruster and has been tested experimentally and plasma jet velocities of approximately 50 kilometers per second have been obtained. The plasma jet structure has been photographed with 10 ns exposure times to reveal a stable and repeatable plasma structure. Data for velocity profile information has been obtained using light pipes embedded in the gun walls to record the plasma transit at various barrel locations. Preliminary spatially resolved spectral data and magnetic field probe data are also presented. A high speed triggering system has been developed and tested as a means of reducing the gun "jitter". This jitter has been characterized and future work for second generation "ultra-low jitter" gun development is identified.

Vlasov Simulation of Electrostatic Solitary Structures in Multi-Component Plasmas

NASA Technical Reports Server (NTRS)

Umeda, Takayuki; Ashour-Abdalla, Maha; Pickett, Jolene S.; Goldstein, Melvyn L.

2012-01-01

Electrostatic solitary structures have been observed in the Earth's magnetosheath by the Cluster spacecraft. Recent theoretical work has suggested that these solitary structures are modeled by electron acoustic solitary waves existing in a four-component plasma system consisting of core electrons, two counter-streaming electron beams, and one species of background ions. In this paper, the excitation of electron acoustic waves and the formation of solitary structures are studied by means of a one-dimensional electrostatic Vlasov simulation. The present result first shows that either electron acoustic solitary waves with negative potential or electron phase-space holes with positive potential are excited in four-component plasma systems. However, these electrostatic solitary structures have longer duration times and higher wave amplitudes than the solitary structures observed in the magnetosheath. The result indicates that a high-speed and small free energy source may be needed as a fifth component. An additional simulation of a five-component plasma consisting of a stable four-component plasma and a weak electron beam shows the generation of small and fast electron phase-space holes by the bump-on-tail instability. The physical properties of the small and fast electron phase-space holes are very similar to those obtained by the previous theoretical analysis. The amplitude and duration time of solitary structures in the simulation are also in agreement with the Cluster observation.

Spatial distribution of the wave field of the surface modes sustaining filamentary discharges

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

Lishev, St.; Shivarova, A.; Tarnev, Kh.

2008-01-01

The study presents the electrodynamical description of surface-wave-sustained discharges contracted in filamentary structures. The results are for the spatial distribution of the wave field and for the wave propagation characteristics obtained from a two-dimensional model developed for describing surface-wave behavior in plasmas with an arbitrary distribution of the plasma density. In accordance with the experimental observations of filamentary discharges, the plasma density distribution considered is completed by cylindrically shaped gas-discharge channels extended along the discharge length and positioned in the out-of-center region of the discharge, equidistantly in an azimuthal direction. Due to the two-dimensional inhomogeneity of the plasma density ofmore » the filamentary structure, the eigen surface mode of the structure is a hybrid wave, with all--six--field components. For identification of its behavior, the surface wave properties in the limiting cases of a plasma ring and a single filament--both radially inhomogeneous--are involved in the discussions. The presentation of the results is for filamentary structures with a decreasing number of filaments (from 10 to 2) starting with the plasma ring, the latter supporting propagation of an azimuthally symmetric wave. Due to the resonance absorption of the surface waves, always present because of the smooth variation of the plasma density, the contours of the critical density are those guiding the surface wave propagation. Decreasing number of filaments in the structure leads to localization of the amplitudes of the wave-field components around the filaments. By analogy with the spatial distribution of the wave field in the plasma ring, the strong resonance enhancement of the wave-field components is along that part of the contour of the critical density which is far off the center of the filamentary structure. The analysis of the spatial distribution of the field components of the filamentary structure shows that the hybrid wave is an eigenmode of the whole structure, i.e., the wave field does not appear as a superposition of fields of eigenmodes of the separated filaments completing it. It is stressed that the spatial distribution of the field components of the eigen hybrid mode of the filamentary structure has an azimuthally symmetric background field.« less

Fitting Multimeric Protein Complexes into Electron Microscopy Maps Using 3D Zernike Descriptors

PubMed Central

Esquivel-Rodríguez, Juan; Kihara, Daisuke

2012-01-01

A novel computational method for fitting high-resolution structures of multiple proteins into a cryoelectron microscopy map is presented. The method named EMLZerD generates a pool of candidate multiple protein docking conformations of component proteins, which are later compared with a provided electron microscopy (EM) density map to select the ones that fit well into the EM map. The comparison of docking conformations and the EM map is performed using the 3D Zernike descriptor (3DZD), a mathematical series expansion of three-dimensional functions. The 3DZD provides a unified representation of the surface shape of multimeric protein complex models and EM maps, which allows a convenient, fast quantitative comparison of the three dimensional structural data. Out of 19 multimeric complexes tested, near native complex structures with a root mean square deviation of less than 2.5 Å were obtained for 14 cases while medium range resolution structures with correct topology were computed for the additional 5 cases. PMID:22417139

Fitting multimeric protein complexes into electron microscopy maps using 3D Zernike descriptors.

PubMed

Esquivel-Rodríguez, Juan; Kihara, Daisuke

2012-06-14

A novel computational method for fitting high-resolution structures of multiple proteins into a cryoelectron microscopy map is presented. The method named EMLZerD generates a pool of candidate multiple protein docking conformations of component proteins, which are later compared with a provided electron microscopy (EM) density map to select the ones that fit well into the EM map. The comparison of docking conformations and the EM map is performed using the 3D Zernike descriptor (3DZD), a mathematical series expansion of three-dimensional functions. The 3DZD provides a unified representation of the surface shape of multimeric protein complex models and EM maps, which allows a convenient, fast quantitative comparison of the three-dimensional structural data. Out of 19 multimeric complexes tested, near native complex structures with a root-mean-square deviation of less than 2.5 Å were obtained for 14 cases while medium range resolution structures with correct topology were computed for the additional 5 cases.

Rotating plasma structures in the cross-field discharge of Hall thrusters

NASA Astrophysics Data System (ADS)

Mazouffre, Stephane; Grimaud, Lou; Tsikata, Sedina; Matyash, Konstantin

2016-09-01

Rotating plasma structures, also termed rotating spokes, are observed in various types of low-pressure discharges with crossed electric and magnetic field configurations, such as Penning sources, magnetron discharges, negative ion sources and Hall thrusters. Such structures correspond to large-scale high-density plasma blocks that rotate in the E×B drift direction with a typical frequency on the order of a few kHz. Although such structures have been extensively studied in many communities, the mechanism at their origin and their role in electron transport across the magnetic field remain unknown. Here, we will present insights into the nature of spokes, gained from a combination of experiments and advanced particle-in-cell numerical simulations that aim at better understanding the physics and the impact of rotating plasma structures in the ExB discharge of the Hall thruster. As rotating spokes appear in the ionization region of such thrusters, and are therefore difficult to probe with diagnostics, experiments have been performed with a wall-less Hall thruster. In this configuration, the entire plasma discharge is pushed outside the dielectric cavity, through which the gas is injected, using the combination of specific magnetic field topology with appropriate anode geometry.

First CLUSTER plasma and magnetic field measurements of flux transfer events in conjunction with their ionospheric flow signatures

NASA Astrophysics Data System (ADS)

Rae, I. J.; Taylor, M. G.; Lavraud, B.; Cowley, S. W.; Lester, M.; Fenrich, F. R.; Fazakerley, A.; Räme, H.; Sofko, G.; Balogh, A.

2001-12-01

The launch of the Cluster satellite constellation allows, amongst other things, the study of the small-scale spatio-temporal structures in the near-Earth geospace. We present a case study of the high-altitude northern hemispheric cusp by the Cluster-II spacecraft constellation under southward IMF conditions. During this interval Cluster traversed the northern hemispheric dayside region and crossed the magnetopause close to the noon-midnight meridian, and observed both the plasma and magnetic field observations of transient reconnection for a number of hours. Throughout this interval, the ionospheric footprint of the spacecraft maps into the Canadian sector of the Earth's ionosphere into the Saskatoon and Kapuskasing HF radars fields-of-view. This SuperDARN HF radar pair observe the ionospheric flows generated by this transient reconnection during this interval at approximately the same magnetic latitude and local time. The calculated orientation of the reconnected flux tubes is found to be in accordance with the prevailing IMF conditions and the direction of motion of the excited ionospheric flows. We discuss these observations in terms of transient magnetic flux transfer and in terms of the size and location of the active reconnection X-line at the low-latitude magnetopause.

MESSENGER's first Mercury flyby: A summary of scientific observations

NASA Astrophysics Data System (ADS)

Solomon, Sean C.; McNutt, Ralph L.; Boynton, William V.; Evans, Larry G.; Head, James W.; Krimigis, Stamatios M.; Murchie, Scott; Phillips, Roger J.; Slavin, James A.; Zuber, Maria T.

The MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft, developed under NASA's Discovery Program, will be the first probe to orbit the planet Mercury in March 2011. Launched in August 2004, MESSENGER successfully completed the first of three flybys of Mercury in January 2008. The Mercury Dual Imaging System acquired an 11-color mosaic of part of the hemisphere not seen by Mariner 10, including the entire Caloris basin; several large monochrome mosaics at a range of resolutions; a series of color frames designed for photometric analysis; and inbound and outbound movies. The Mercury Atmospheric and Surface Composition Spectrometer obtained the first high-resolution spectral reflectance measurements (at ultraviolet to near-infrared wavelengths) of surface composition, conducted limb scans of exospheric species, and mapped the composition and structure of the tail region. The Magnetometer measured Mercury's internal field at low latitudes and documented the major plasma boundaries of Mercury's magnetosphere. The Energetic Particle and Plasma Spectrometer made the first measurements of low-energy ions in Mercury's magnetosphere. The Mercury Laser Altimeter carried out the first space altimetric profile of the planet. Other instruments in the payload provided baseline measurements that will aid in the interpretation of data from the mission orbital phase. Together, the MESSENGER flyby observations have begun to advance our understanding of the innermost planet.

Numerical simulation of current-free double layers created in a helicon plasma device

NASA Astrophysics Data System (ADS)

Rao, Sathyanarayan; Singh, Nagendra

2012-09-01

Two-dimensional simulations reveal that when radially confined source plasma with magnetized electrons and unmagnetized ions expands into diverging magnetic field B, a current-free double layer (CFDL) embedded in a conical density structure forms, as experimentally measured in the Australian helicon plasma device (HPD). The magnetized electrons follow the diverging B while the unmagnetized ions tend to flow directly downstream of the source, resulting in a radial electric field (E⊥) structure, which couples the ion and electron flows. Ions are transversely (radially) accelerated by E⊥ on the high potential side of the double layer in the CFDL. The accelerated ions are trapped near the conical surface, where E⊥ reverses direction. The potential structure of the CFDL is U-shaped and the plasma density is enhanced on the conical surface. The plasma density is severely depleted downstream of the parallel potential drop (φ||o) in the CFDL; the density depletion and the potential drop are related by quasi-neutrality condition, including the divergence in the magnetic field and in the plasma flow in the conical structure. The potential and density structures, the CFDL spatial size, its electric field strengths and the electron and ion velocities and energy distributions in the CFDL are found to be in good agreements with those measured in the Australian experiment. The applicability of our results to measured axial potential profiles in magnetic nozzle experiments in HPDs is discussed.

Membrane androgen receptor characteristics of human ZIP9 (SLC39A) zinc transporter in prostate cancer cells: Androgen-specific activation and involvement of an inhibitory G protein in zinc and MAP kinase signaling.

PubMed

Thomas, Peter; Pang, Yefei; Dong, Jing

2017-05-15

Characteristics of novel human membrane androgen receptor (mAR), ZIP9 (SLC39A9), were investigated in ZIP9-transfected PC-3 cells (PC3-ZIP9). Ligand blot analysis showed plasma membrane [ 3 H]-T binding corresponds to the position of ZIP9 on Western blots which suggests ZIP9 can bind [ 3 H]-T alone, without a protein partner. Progesterone antagonized testosterone actions, blocking increases in zinc, Erk phosphorylation and apoptosis, further evidence that ZIP9 is specifically activated by androgens. Pre-treatment with GTPγS and pertussis toxin decreased plasma membrane [ 3 H]-T binding and blocked testosterone-induced increases in Erk phosphorylation and intracellular zinc, indicating ZIP9 is coupled to an inhibitory G protein (Gi) that mediates both MAP kinase and zinc signaling. Testosterone treatment of nuclei and mitochondria which express ZIP9 decreased their zinc contents, suggesting ZIP9 also regulates free zinc through releasing it from these intracellular organelles. The results show ZIP9 is a specific Gi coupled-mAR mediating testosterone-induced MAP kinase and zinc signaling in PC3-ZIP9 cells. Copyright © 2017 Elsevier B.V. All rights reserved.

Adaptive plasma for cancer therapy: physics, mechanism and applications

NASA Astrophysics Data System (ADS)

Keidar, Michael

2017-10-01

One of the most promising applications of cold atmospheric plasma (CAP) is the cancer therapy. The uniqueness of plasma is in its ability to change composition in situ. Plasma self-organization could lead to formation of coherent plasma structures. These coherent structures tend to modulate plasma chemistry and composition, including reactive species, the electric field and charged particles. Formation of coherent plasma structures allows the plasma to adapt to external boundary conditions, such as different cells types and their contextual tissues. In this talk we will explore possibilities and opportunities that the adaptive plasma therapeutic system might offer. We shall define such an adaptive system as a plasma device that is able to adjust the plasma composition to obtain optimal desirable outcomes through its interaction with cells and tissues. The efficacy of cold plasma in a pre-clinical model of various cancer types such as lung, bladder, breast, head, neck, brain and skin has been demonstrated. Both in-vitro and in-vivo studies revealed that cold plasmas selectively kill cancer cells. Recently mechanism of plasma selectivity based on aquaporin hypothesis has been proposed. Aquaporins (AQPs) are the confirmed membrane channels of H2O2 and other large molecules. We have demonstrated that the anti-cancer capacity of plasma could be inhibited by silencing the expression of AQPs. Additional possible cell feedback mechanism was recently discovered. It is associated with production of reactive species during direct CAP treatment by cancer cells. Selective production of hydrogen peroxide by different cells can lead to adaptation of chemistry at the plasma-cell interface based on the cellular input. In particular we have found that the discharge voltage is an important factor affecting the ratio of reactive oxygen species to reactive nitrogen species in the gas phase and this correlates well with effect of hydrogen peroxide production by cells. This work was supported by a National Science Foundation, Grant No. 1465061.

Intermittency, nonlinear dynamics and dissipation in the solar wind and astrophysical plasmas

PubMed Central

Matthaeus, W. H.; Wan, Minping; Servidio, S.; Greco, A.; Osman, K. T.; Oughton, S.; Dmitruk, P.

2015-01-01

An overview is given of important properties of spatial and temporal intermittency, including evidence of its appearance in fluids, magnetofluids and plasmas, and its implications for understanding of heliospheric plasmas. Spatial intermittency is generally associated with formation of sharp gradients and coherent structures. The basic physics of structure generation is ideal, but when dissipation is present it is usually concentrated in regions of strong gradients. This essential feature of spatial intermittency in fluids has been shown recently to carry over to the realm of kinetic plasma, where the dissipation function is not known from first principles. Spatial structures produced in intermittent plasma influence dissipation, heating, and transport and acceleration of charged particles. Temporal intermittency can give rise to very long time correlations or a delayed approach to steady-state conditions, and has been associated with inverse cascade or quasi-inverse cascade systems, with possible implications for heliospheric prediction. PMID:25848085

Eddy, drift wave and zonal flow dynamics in a linear magnetized plasma

PubMed Central

Arakawa, H.; Inagaki, S.; Sasaki, M.; Kosuga, Y.; Kobayashi, T.; Kasuya, N.; Nagashima, Y.; Yamada, T.; Lesur, M.; Fujisawa, A.; Itoh, K.; Itoh, S.-I.

2016-01-01

Turbulence and its structure formation are universal in neutral fluids and in plasmas. Turbulence annihilates global structures but can organize flows and eddies. The mutual-interactions between flow and the eddy give basic insights into the understanding of non-equilibrium and nonlinear interaction by turbulence. In fusion plasma, clarifying structure formation by Drift-wave turbulence, driven by density gradients in magnetized plasma, is an important issue. Here, a new mutual-interaction among eddy, drift wave and flow in magnetized plasma is discovered. A two-dimensional solitary eddy, which is a perturbation with circumnavigating motion localized radially and azimuthally, is transiently organized in a drift wave – zonal flow (azimuthally symmetric band-like shear flows) system. The excitation of the eddy is synchronized with zonal perturbation. The organization of the eddy has substantial impact on the acceleration of zonal flow. PMID:27628894

Investigating plasma viscosity with fast framing photography in the ZaP-HD Flow Z-Pinch experiment

NASA Astrophysics Data System (ADS)

Weed, Jonathan Robert

The ZaP-HD Flow Z-Pinch experiment investigates the stabilizing effect of sheared axial flows while scaling toward a high-energy-density laboratory plasma (HEDLP > 100 GPa). Stabilizing flows may persist until viscous forces dissipate a sheared flow profile. Plasma viscosity is investigated by measuring scale lengths in turbulence intentionally introduced in the plasma flow. A boron nitride turbulence-tripping probe excites small scale length turbulence in the plasma, and fast framing optical cameras are used to study time-evolved turbulent structures and viscous dissipation. A Hadland Imacon 790 fast framing camera is modified for digital image capture, but features insufficient resolution to study turbulent structures. A Shimadzu HPV-X camera captures the evolution of turbulent structures with great spatial and temporal resolution, but is unable to resolve the anticipated Kolmogorov scale in ZaP-HD as predicted by a simplified pinch model.

A statistical survey of heat input parameters into the cusp thermosphere

NASA Astrophysics Data System (ADS)

Moen, J. I.; Skjaeveland, A.; Carlson, H. C.

2017-12-01

Based on three winters of observational data, we present those ionosphere parameters deemed most critical to realistic space weather ionosphere and thermosphere representation and prediction, in regions impacted by variability in the cusp. The CHAMP spacecraft revealed large variability in cusp thermosphere densities, measuring frequent satellite drag enhancements, up to doublings. The community recognizes a clear need for more realistic representation of plasma flows and electron densities near the cusp. Existing average-value models produce order of magnitude errors in these parameters, resulting in large under estimations of predicted drag. We fill this knowledge gap with statistics-based specification of these key parameters over their range of observed values. The EISCAT Svalbard Radar (ESR) tracks plasma flow Vi , electron density Ne, and electron, ion temperatures Te, Ti , with consecutive 2-3 minute windshield-wipe scans of 1000x500 km areas. This allows mapping the maximum Ti of a large area within or near the cusp with high temporal resolution. In magnetic field-aligned mode the radar can measure high-resolution profiles of these plasma parameters. By deriving statistics for Ne and Ti , we enable derivation of thermosphere heating deposition under background and frictional-drag-dominated magnetic reconnection conditions. We separate our Ne and Ti profiles into quiescent and enhanced states, which are not closely correlated due to the spatial structure of the reconnection foot point. Use of our data-based parameter inputs can make order of magnitude corrections to input data driving thermosphere models, enabling removal of previous two fold drag errors.

Currents and Flows in Distant Magnetospheres

NASA Technical Reports Server (NTRS)

Kivelson, Margaret Galland

2000-01-01

Space scientists have explored, described, and explained the terrestrial magnetosphere for four decades. Rarely do they point out that the planetary and solar wind parameters controlling the size, shape, and activity of Earth's magnetosphere map out only a small portion of the space of dimensionless parameters that govern magnetospheric properties. With the discovery of Ganymede's magnetosphere, the range of parameters relevant to magnetospheric studies has grown by orders of magnitude. Consider the extremes of Ganymede's and Jupiter's magnetospheres. Jupiter's magnetosphere forms within a plasma flowing at super-Alfvenic speed, whereas Ganymede's forms in a sub-Alfvenic flow. The scale sizes of these magnetospheres, characterized by distances to the magnetopause of order 7x10(exp 6) km and 5x10(exp 3) km, respectively, differ by three orders of magnitude, ranging from 100 to 0.1 times the scale of Earth's magnetosphere. The current systems that control the structure and dynamics of a magnetosphere depend on specific plasma and field properties. Magnetopause currents at Ganymede differ greatly from the forms familiar for Earth and Jupiter, principally because the Mach number of the ambient plasma flow greatly influences the shape of the magnetosphere. A magnetodisk current, present at Jupiter because of its rapid rotation, is absent at Earth and Ganymede. The ring current, extensively investigated at Earth, is probably unimportant at Ganymede because the dynamical variations of the external flow are slow. The ring current is subsumed within the magnetodisk current at Jupiter. This paper describes and contrasts aspects of these and other current systems for the three bodies.

On the nonlinear trapping nature of undamped, coherent structures in collisionless plasmas and its impact on stability

NASA Astrophysics Data System (ADS)

Schamel, Hans; Mandal, Debraj; Sharma, Devendra

2017-03-01

An outstanding notion for collisionless plasmas is the essential nonlinear character of their coherent structures, which in the stationary, weak amplitude limit are described by a continuum of cnoidal electron and ion hole modes governed by a multiparametric nonlinear dispersion relation. The well-known discrete structure of undamped linear plasma modes is seamlessly embedded in this nonlinear continuum as the microscopic texture of plasma begins to reveal itself in the high temperature collisionless plasma limit. This transforms the linear-threshold-based operating mechanism of plasma turbulence into a fundamental nonlinear, multifaceted one. Based on a comprehensive three-level description of increasing profundity, a proof of this novel dictum is presented, which makes use of the joint properties of such structures, their coherency and stationarity, and uses in succession a fluid, linear Vlasov and a full Vlasov description. It unifies discrete and continuum limits by resolving the inevitable resonant region and shows that coherent electrostatic equilibria are generally controlled by kinetic particle trapping and are hence fundamentally nonlinear. By forging a link between damped and growing wave solutions, these modes render plasma stability complex and difficult to evaluate due to the entangled pattern of the stability boundary in function and parameter space, respectively. A direct consequence is the existence of negative energy modes of arbitrarily small amplitudes in the subcritical region of the two-stream instability as well as the failure of linear Landau (Vlasov, van Kampen) theory, whenever resonant particles are involved, in addressing the onset of instability in a current-carrying plasma. Responsible for this subtle phase space behavior is hence the thresholdless omnipresence of the trapping nonlinearity originating from coherency. A high resolution, exact-mass-ratio, multispecies, and collisionless plasma simulation is employed to illustrate exemplarily how tiny seed fluctuations in phase-space can act as a triggering agent for a subcritical plasma excitation verifying an access to these modes in the noisy, collisionless plasma limit.

Effect of the three-dimensional structure of laser emission on the dynamics of low-threshold optical breakdown plasmas

NASA Astrophysics Data System (ADS)

Anisimov, V. N.; Arutiunian, R. V.; Bol'Shov, L. A.; Derkach, O. N.; Kanevskii, M. F.

1989-03-01

The effect of the transverse structure of pulsed CO2 laser emission on the dynamics of laser-induced detonation waves propagating from a metal surface and on plasma transparency recovery is investigated theoretically and experimentally. Particular attention is given to breakdown initiation near the surface. It is suggested that the inclusion of refraction in the plasma into a self-consistent numerical mode is essential for the adequate quantitative description of experimental data on the interaction of laser emission with low-threshold optical breakdown plasmas.

Hollow structure formation of intense ion beams with sharp edge in background plasmas

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

Hu, Zhang-Hu; Wang, You-Nian, E-mail: ynwang@dlut.edu.cn

The transport of intense ion beams with sharp radial beam edge in plasmas has been studied with two-dimensional electromagnetic particle simulations. The initial solid beam evolves into a hollow beam due to the nonlinear sharp transverse force peak in the regions of beam edge. The magnitude and nonlinearity of this peak are enhanced as the ion beam travels further into the plasma, due to the self-consistent interactions between the beam ions and the plasma electrons. This structure formation is shown to be independent on the beam radius.

Cardiovascular effects of simulated zero-gravity in humans

NASA Astrophysics Data System (ADS)

Bonde-Petersen, F.; Suzuki, Y.; Sadámoto, T.; Juel Christensen, N.

Head-down and heat-up tilted bedrest (5 degrees) and head out water immersion (HOWI) for 6 hr were compared. Parameters: Cardiac output (rebreathing method), blood pressure (arm cuff), forearm blood flow (venous occlusion plethysmography), total peripheral (TPR), and forearm vascular (FVR) resistances, Hct, Hb, relativē plasma volume (PV) changes, and plasma catecholamines (single-isotope assay). During HOWI there was as expected a decrement in TPR, FVR, Mean arterial pressure (MAP, from 100 to 80 mmHg), Hct, and PV, and—as a new finding—catecholamines, which were 30-50% lower compared with both + 5 and - 5 degrees bedrest. During head down tilt, MAP was elevated (to 100-110 mmHg) and catecholamines did not fall, while TPR and FVR slowly decreased over 6 hr. HOWI is a stronger stimulus than - 5 degrees bedrest, probably because HOWI elevates central venous pressure more markedly emptying the peripheral veins, while bedrest permits a distension of veins, which induces an increase in sympathetic nervous activity.

Stochastic Ion Heating by the Lower-Hybrid Waves

NASA Technical Reports Server (NTRS)

Khazanov, G.; Tel'nikhin, A.; Krotov, A.

2011-01-01

The resonance lower-hybrid wave-ion interaction is described by a group (differentiable map) of transformations of phase space of the system. All solutions to the map belong to a strange attractor, and chaotic motion of the attractor manifests itself in a number of macroscopic effects, such as the energy spectrum and particle heating. The applicability of the model to the problem of ion heating by waves at the front of collisionless shock as well as ion acceleration by a spectrum of waves is discussed. Keywords: plasma; ion-cyclotron heating; shocks; beat-wave accelerator.

Energy Spectral Behaviors of Communication Networks of Open-Source Communities

PubMed Central

Yang, Jianmei; Yang, Huijie; Liao, Hao; Wang, Jiangtao; Zeng, Jinqun

2015-01-01

Large-scale online collaborative production activities in open-source communities must be accompanied by large-scale communication activities. Nowadays, the production activities of open-source communities, especially their communication activities, have been more and more concerned. Take CodePlex C # community for example, this paper constructs the complex network models of 12 periods of communication structures of the community based on real data; then discusses the basic concepts of quantum mapping of complex networks, and points out that the purpose of the mapping is to study the structures of complex networks according to the idea of quantum mechanism in studying the structures of large molecules; finally, according to this idea, analyzes and compares the fractal features of the spectra in different quantum mappings of the networks, and concludes that there are multiple self-similarity and criticality in the communication structures of the community. In addition, this paper discusses the insights and application conditions of different quantum mappings in revealing the characteristics of the structures. The proposed quantum mapping method can also be applied to the structural studies of other large-scale organizations. PMID:26047331

Measurements of ion energies during plasma heating of the Proto-MPEX High Intensity Plasma Source

NASA Astrophysics Data System (ADS)

Caughman, J. B. O.; Goulding, R. H.; Biewer, T. M.; Bigelow, T. S.; Caneses, J.; Diem, S. J.; Green, D. L.; Isler, R. C.; Rapp, J.; Piotrowicz, P.; Beers, C. J.; Kafle, N.; Showers, M. A.

2017-10-01

The Prototype Materials Plasma Exposure eXperiment (Proto-MPEX) is a linear high-intensity RF plasma source that combines a high-density helicon plasma generator with ion and electron heating sections. It is being used to study the physics of heating over-dense plasmas in a linear configuration with the goal of delivering a plasma heat flux of 10 MW/m2 at a target. The helicon plasma is produced by coupling 13.56 MHz RF power at levels >100 kW. Additional heating is provided by ion cyclotron heating (ICH) ( 25 kW) and electron Bernstein wave (EBW) heating ( 25 kW) at 28 GHz. Measurements of the ion energy distribution with a retarding field energy analyzer (RFEA) show an increase in ion energies in the edge of the plasma when ICH is applied, which is consistent with COMSOL modeling of the power deposition from the antenna. Views of the target plate with an infrared camera show an increase in the surface temperature at large radii during ICH, and these areas map back to magnetic field lines near the antenna. The change in the power deposition at the target during ICH is compared with Thomson Scattering and RFEA measurements near the target. ORNL is managed by UT-Battelle, LLC, for the U.S. DOE under contract DE-AC-05-00OR22725.

Hamiltonian structure of the guiding center plasma model

NASA Astrophysics Data System (ADS)

Burby, J. W.; Sengupta, W.

2018-02-01

The guiding center plasma model (also known as kinetic MHD) is a rigorous sub-cyclotron-frequency closure of the Vlasov-Maxwell system. While the model has been known for decades and it plays a fundamental role in describing the physics of strongly magnetized collisionless plasmas, its Hamiltonian structure has never been found. We provide explicit expressions for the model's Poisson bracket and Hamiltonian and thereby prove that the model is an infinite-dimensional Hamiltonian system. The bracket is derived in a manner which ensures that it satisfies the Jacobi identity. We also report on several previously unknown circulation theorems satisfied by the guiding center plasma model. Without knowledge of the Hamiltonian structure, these circulation theorems would be difficult to guess.

Process to make structured particles

DOEpatents

Knapp, Angela Michelle; Richard, Monique N; Luhrs, Claudia; Blada, Timothy; Phillips, Jonathan

2014-02-04

Disclosed is a process for making a composite material that contains structured particles. The process includes providing a first precursor in the form of a dry precursor powder, a precursor liquid, a precursor vapor of a liquid and/or a precursor gas. The process also includes providing a plasma that has a high field zone and passing the first precursor through the high field zone of the plasma. As the first precursor passes through the high field zone of the plasma, at least part of the first precursor is decomposed. An aerosol having a second precursor is provided downstream of the high field zone of the plasma and the decomposed first material is allowed to condense onto the second precursor to from structured particles.

A DE-1/whistler study of the thermal plasma structure and dynamics in the dusk bulge sector of the magnetosphere

NASA Technical Reports Server (NTRS)

Carpenter, D. L.

1992-01-01

The objective of this research was to obtain new understanding of the thermal plasma structure and dynamics of the plasmasphere bulge region of the magnetosphere, with special emphasis on the erosion process that results in a reduction in plasmasphere size and on the manner in which erosion leads to the presence of patches of dense plasma in the middle and outer afternoon-dusk magnetosphere. Case studies involving data from the DE 1, GEOS 2, and ISEE 1 satellites and from ground whistler stations Siple, Halley, and Kerguelen were used. A copy of the published paper entitled 'A case study of plasma structure in the dusk sector associated with enhanced magnetospheric convection,' is included.

Image processing for optical mapping.

PubMed

Ravindran, Prabu; Gupta, Aditya

2015-01-01

Optical Mapping is an established single-molecule, whole-genome analysis system, which has been used to gain a comprehensive understanding of genomic structure and to study structural variation of complex genomes. A critical component of Optical Mapping system is the image processing module, which extracts single molecule restriction maps from image datasets of immobilized, restriction digested and fluorescently stained large DNA molecules. In this review, we describe robust and efficient image processing techniques to process these massive datasets and extract accurate restriction maps in the presence of noise, ambiguity and confounding artifacts. We also highlight a few applications of the Optical Mapping system.

Plasma-Induced Degradation of Quercetin Associated with the Enhancement of Biological Activities.

PubMed

Kim, Tae Hoon; Lee, Jaemin; Kim, Hyun-Joo; Jo, Cheorun

2017-08-16

Nonthermal plasma is a promising technology to improve the safety and to extend the shelf-life of various minimally processed foods. However, research on plasma-induced systemic degradation related to changes in chemical structure and biological activity is still very limited. In this study, the enhancement of biological activity and the mechanism of degradation of the most common type of flavonol, quercetin, induced by a dielectric barrier discharge (DBD) plasma were investigated. Quercetin is dissolved in methanol and exposed to nonthermal DBD plasma for 5, 10, 20, and 30 min. The quercetin treated with the plasma for 20 min showed rapidly increased α-glucosidase inhibitory and radical scavenging activities compared to those of parent quercetin. The structures of the degradation products 1-3 from the quercetin treated with the plasma for 20 min were isolated and characterized by interpretation of their spectroscopic data. Among the generated products, (±)-alphitonin (1) exhibited significantly improved antidiabetic and antioxidant properties compared to those of the parent quercetin. The antidiabetic and antioxidant properties were measured by α-glucosidase inhibition and 1,1-diphenyl-2-picrylhydrazyl radical scavenging assays. These results suggested that structural changes in quercetin induced by DBD plasma might be attributable to improving the biological activity.

Computational study of sheath structure in oxygen containing plasmas at medium pressures

NASA Astrophysics Data System (ADS)

Hrach, Rudolf; Novak, Stanislav; Ibehej, Tomas; Hrachova, Vera

2016-09-01

Plasma mixtures containing active species are used in many plasma-assisted material treatment technologies. The analysis of such systems is rather difficult, as both physical and chemical processes affect plasma properties. A combination of experimental and computational approaches is the best suited, especially at higher pressures and/or in chemically active plasmas. The first part of our study of argon-oxygen mixtures was based on experimental results obtained in the positive column of DC glow discharge. The plasma was analysed by the macroscopic kinetic approach which is based on the set of chemical reactions in the discharge. The result of this model is a time evolution of the number densities of each species. In the second part of contribution the detailed analysis of processes taking place during the interaction of oxygen containing plasma with immersed substrates was performed, the results of the first model being the input parameters. The used method was the particle simulation technique applied to multicomponent plasma. The sheath structure and fluxes of charged particles to substrates were analysed in the dependence on plasma pressure, plasma composition and surface geometry.

Application of phyto-indication and radiocesium indicative methods for microrelief mapping

NASA Astrophysics Data System (ADS)

Panidi, E.; Trofimetz, L.; Sokolova, J.

2016-04-01

Remote sensing technologies are widely used for production of Digital Elevation Models (DEMs), and geomorphometry techniques are valuable tools for DEM analysis. One of the broadly used applications of these technologies and techniques is relief mapping. In the simplest case, we can identify relief structures using DEM analysis, and produce a map or map series to show the relief condition. However, traditional techniques might fail when used for mapping microrelief structures (structures below ten meters in size). In this case high microrelief dynamics lead to technological and conceptual difficulties. Moreover, erosion of microrelief structures cannot be detected at the initial evolution stage using DEM modelling and analysis only. In our study, we investigate the possibilities and specific techniques for allocation of erosion microrelief structures, and mapping techniques for the microrelief derivatives (e.g. quantitative parameters of microrelief). Our toolset includes the analysis of spatial redistribution of the soil pollutants and phyto-indication analysis, which complement the common DEM modelling and geomorphometric analysis. We use field surveys produced at the test area, which is arable territory with high erosion risks. Our main conclusion at the current stage is that the indicative methods (i.e. radiocesium and phyto-indication methods) are effective for allocation of the erosion microrelief structures. Also, these methods need to be formalized for convenient use.

Effect of Coulomb Collisions on Low Gas Pressure Plasmas

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

Nanbu, K.; Furubayashi, T.

2006-05-05

A recent trend in material processing plasmas is the use of a low gas pressure and high plasma density. In such plasmas, Coulomb collisions among charged particles has been considered to have a significant effect on plasma structure. By use of Bobylev and Nanbu's theory [Phy. Rev. E, 61(2000), 4576], this effect on argon plasmas and oxygen plasmas generated by a capacitive discharge is examined. It is found that the effect is appreciable only for oxygen plasmas.

Isolation and characterization of a cDNA clone specific for avian vitellogenin II.

PubMed Central

Protter, A A; Wang, S Y; Shelness, G S; Ostapchuk, P; Williams, D L

1982-01-01

A clone for vitellogenin, a major avian, estrogen responsive egg yolk protein, was isolated from the cDNA library of estrogen-induced rooster liver. Two forms of plasma vitellogenin, vitellogenin I (VTG I) and vitellogenin II (VTG II), distinguishable on the basis of their unique partial proteolysis maps, have been characterized and their corresponding hepatic precursor forms identified. We have used this criterion to specifically characterize which vitellogenin protein had been cloned. Partial proteolysis maps of BTG I and VTG II standards, synthesized in vivo, were compared to maps of protein synthesized in vitro using RNA hybrid-selected by the vitellogenin plasmid. Eight major digest fragments were found common to the in vitro synthesized vitellogenin and the VTG II standard while no fragments were observed to correspond to the VTG I map. A restriction map of the VTG II cDNA clone permits comparison to previously described cDNA and genomic vitellogenin clones. Images PMID:6182527

Measurements of ion species separation in strong plasma shocks

NASA Astrophysics Data System (ADS)

Rinderknecht, Hans

2017-10-01

Shocks are important dynamic phenomena in inertial confinement fusion (ICF) and astrophysical plasmas. While the relationship between upstream and downstream plasmas far from the shock front is fully determined by conservation equations, the structure of shock fronts is determined by dynamic kinetic processes. Kinetic theory and simulations predict that the width of a strong (M >2) collisional plasma shock front is on the order of tens of ion mean-free-paths. The shock front structure plays an important role for overall dynamics when the shock front width approaches plasma scale lengths, as in the spherically converging shock in the DT-vapor in an ICF implosion. However, there has been no experimental data benchmarking shock front structure in the plasma phase. The structure of a shock front in a plasma with multiple ion species has been directly measured for the first time using a combination of Thomson scattering and proton radiography in experiments on the OMEGA laser. Thomson scattering of a 263.25 nm probe beam is used to diagnose electron density, electron and ion temperature, ion species concentration, and flow velocity in strong shocks (M 5) propagating through low-density (ρ 0.1 mg/cc) plasmas composed of H(98%) +Ne(2%). Within the shock front, velocity separation of the ion species is observed for the first time: the light species (H) accelerates to of order the shocked fluid velocity (450 microns/ns) before the heavy species (Ne) begins to move. This velocity-space separation implies that the separation of ion species occurs at the shock front, a predicted feature of shocks in multi-species plasmas but never observed experimentally until now. Comparison of experimental data with PIC, Vlasov-Fokker-Planck, and multi-component hydrodynamic simulations will be presented.

Structure and Dynamics of Colliding Plasma Jets

DOE PAGES

Li, C.; Ryutov, D.; Hu, S.; ...

2013-12-01

Monoenergetic-proton radiographs of laser-generated, high-Mach-number plasma jets colliding at various angles shed light on the structures and dynamics of these collisions. The observations compare favorably with results from 2D hydrodynamic simulations of multistream plasma jets, and also with results from an analytic treatment of electron flow and magnetic field advection. In collisions of two noncollinear jets, the observed flow structure is similar to the analytic model’s prediction of a characteristic feature with a narrow structure pointing in one direction and a much thicker one pointing in the opposite direction. Spontaneous magnetic fields, largely azimuthal around the colliding jets and generatedmore » by the well-known ∇T e ×∇n e Biermann battery effect near the periphery of the laser spots, are demonstrated to be “frozen in” the plasma (due to high magnetic Reynolds number R M ~5×10⁴) and advected along the jet streamlines of the electron flow. These studies provide novel insight into the interactions and dynamics of colliding plasma jets.« less

Laser Wakefield Acceleration: Structural and Dynamic Studies. Final Technical Report ER40954

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

Downer, Michael C.

2014-04-30

Particle accelerators enable scientists to study the fundamental structure of the universe, but have become the largest and most expensive of scientific instruments. In this project, we advanced the science and technology of laser-plasma accelerators, which are thousands of times smaller and less expensive than their conventional counterparts. In a laser-plasma accelerator, a powerful laser pulse exerts light pressure on an ionized gas, or plasma, thereby driving an electron density wave, which resembles the wake behind a boat. Electrostatic fields within this plasma wake reach tens of billions of volts per meter, fields far stronger than ordinary non-plasma matter (suchmore » as the matter that a conventional accelerator is made of) can withstand. Under the right conditions, stray electrons from the surrounding plasma become trapped within these “wake-fields”, surf them, and acquire energy much faster than is possible in a conventional accelerator. Laser-plasma accelerators thus might herald a new generation of compact, low-cost accelerators for future particle physics, x-ray and medical research. In this project, we made two major advances in the science of laser-plasma accelerators. The first of these was to accelerate electrons beyond 1 gigaelectronvolt (1 GeV) for the first time. In experimental results reported in Nature Communications in 2013, about 1 billion electrons were captured from a tenuous plasma (about 1/100 of atmosphere density) and accelerated to 2 GeV within about one inch, while maintaining less than 5% energy spread, and spreading out less than ½ milliradian (i.e. ½ millimeter per meter of travel). Low energy spread and high beam collimation are important for applications of accelerators as coherent x-ray sources or particle colliders. This advance was made possible by exploiting unique properties of the Texas Petawatt Laser, a powerful laser at the University of Texas at Austin that produces pulses of 150 femtoseconds (1 femtosecond is 10-15 seconds) in duration and 150 Joules in energy (equivalent to the muzzle energy of a small pistol bullet). This duration was well matched to the natural electron density oscillation period of plasma of 1/100 atmospheric density, enabling efficient excitation of a plasma wake, while this energy was sufficient to drive a high-amplitude wake of the right shape to produce an energetic, collimated electron beam. Continuing research is aimed at increasing electron energy even further, increasing the number of electrons captured and accelerated, and developing applications of the compact, multi-GeV accelerator as a coherent, hard x-ray source for materials science, biomedical imaging and homeland security applications. The second major advance under this project was to develop new methods of visualizing the laser-driven plasma wake structures that underlie laser-plasma accelerators. Visualizing these structures is essential to understanding, optimizing and scaling laser-plasma accelerators. Yet prior to work under this project, computer simulations based on estimated initial conditions were the sole source of detailed knowledge of the complex, evolving internal structure of laser-driven plasma wakes. In this project we developed and demonstrated a suite of optical visualization methods based on well-known methods such as holography, streak cameras, and coherence tomography, but adapted to the ultrafast, light-speed, microscopic world of laser-driven plasma wakes. Our methods output images of laser-driven plasma structures in a single laser shot. We first reported snapshots of low-amplitude laser wakes in Nature Physics in 2006. We subsequently reported images of high-amplitude laser-driven plasma “bubbles”, which are important for producing electron beams with low energy spread, in Physical Review Letters in 2010. More recently, we have figured out how to image laser-driven structures that change shape while propagating in a single laser shot. The latter techniques, which use the methods of computerized tomography, were demonstrated on test objects – e.g. laser-driven filaments in air and glass – and reported in Optics Letters in 2013 and Nature Communications in 2014. Their output is a multi-frame movie rather than a snapshot. Continuing research is aimed at applying these tomographic methods directly to evolving laser-driven plasma accelerator structures in our laboratory, then, once perfected, to exporting them to plasma-based accelerator laboratories around the world as standard in-line metrology instruments.« less

Filamentation in the pinched column of the dense plasma focus

NASA Astrophysics Data System (ADS)

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.

2017-03-01

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 filaments connect the surface of a pinched column with internal plasmoids formed at different combinations of filling and puffing gases and they should transport some current 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 filaments, 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 filaments and balls might be a manifestation of the (i) discrete spatial structure of the current 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.

Preliminary study of the CRRES magnetospheric barium releases

NASA Technical Reports Server (NTRS)

Huba, J. D.; Bernhardt, P. A.; Lyon, J. G.

1992-01-01

Preliminary theoretical and computational analyses of the Combined Release and Radiation Effects Satellite (CRRES) magnetospheric barium releases are presented. The focus of the studies is on the evolution of the diamagnetic cavity which is formed by the barium ions as they expand outward, and on the structuring of the density and magnetic field during the expansion phase of the releases. Two sets of simulation studies are discussed. The first set is based upon a 2D ideal MHD code and provides estimates of the time and length scales associated with the formation and collapse of the diamagnetic cavity. The second set uses a nonideal MHD code; specifically, the Hall term is included. This additional term is critical to the dynamics of sub-Alfvenic plasma expansions, such as the CRRES barium releases, because it leads to instability of the expanding plasma. Detailed simulations of the G4 and G10 releases were performed. In both cases the expanding plasma rapidly structured: the G4 release structured at time t less than about 3 s and developed scale sizes of about 1-2 km, while the G10 release structured at time t less than about 22 s and developed scale sizes of about 10-15 km. It is also found that the diamagnetic cavity size is reduced from those obtained from the ideal MHD results because of the structure. On the other hand, the structuring allows the formation of plasma blobs which appear to free stream across the magnetic field; thus, the barium plasma can propagate to larger distances traverse to the magnetic field than the case where no structuring occurs. Finally, a new normal mode of the system was discovered which may be excited at the leading edge of the expanding barium plasma.

The formation of relativistic plasma structures and their potential role in the generation of cosmic ray electrons

NASA Astrophysics Data System (ADS)

Dieckmann, M. E.

2008-11-01

Recent particle-in-cell (PIC) simulation studies have addressed particle acceleration and magnetic field generation in relativistic astrophysical flows by plasma phase space structures. We discuss the astrophysical environments such as the jets of compact objects, and we give an overview of the global PIC simulations of shocks. These reveal several types of phase space structures, which are relevant for the energy dissipation. These structures are typically coupled in shocks, but we choose to consider them here in an isolated form. Three structures are reviewed. (1) Simulations of interpenetrating or colliding plasma clouds can trigger filamentation instabilities, while simulations of thermally anisotropic plasmas observe the Weibel instability. Both transform a spatially uniform plasma into current filaments. These filament structures cause the growth of the magnetic fields. (2) The development of a modified two-stream instability is discussed. It saturates first by the formation of electron phase space holes. The relativistic electron clouds modulate the ion beam and a secondary, spatially localized electrostatic instability grows, which saturates by forming a relativistic ion phase space hole. It accelerates electrons to ultra-relativistic speeds. (3) A simulation is also revised, in which two clouds of an electron-ion plasma collide at the speed 0.9c. The inequal densities of both clouds and a magnetic field that is oblique to the collision velocity vector result in waves with a mixed electrostatic and electromagnetic polarity. The waves give rise to growing corkscrew distributions in the electrons and ions that establish an equipartition between the electron, the ion and the magnetic energy. The filament-, phase space hole- and corkscrew structures are discussed with respect to electron acceleration and magnetic field generation.

Gravity Maps of Antarctic Lithospheric Structure from Remote-Sensing and Seismic Data

NASA Astrophysics Data System (ADS)

Tenzer, Robert; Chen, Wenjin; Baranov, Alexey; Bagherbandi, Mohammad

2018-02-01

Remote-sensing data from altimetry and gravity satellite missions combined with seismic information have been used to investigate the Earth's interior, particularly focusing on the lithospheric structure. In this study, we use the subglacial bedrock relief BEDMAP2, the global gravitational model GOCO05S, and the ETOPO1 topographic/bathymetric data, together with a newly developed (continental-scale) seismic crustal model for Antarctica to compile the free-air, Bouguer, and mantle gravity maps over this continent and surrounding oceanic areas. We then use these gravity maps to interpret the Antarctic crustal and uppermost mantle structure. We demonstrate that most of the gravity features seen in gravity maps could be explained by known lithospheric structures. The Bouguer gravity map reveals a contrast between the oceanic and continental crust which marks the extension of the Antarctic continental margins. The isostatic signature in this gravity map confirms deep and compact orogenic roots under the Gamburtsev Subglacial Mountains and more complex orogenic structures under Dronning Maud Land in East Antarctica. Whereas the Bouguer gravity map exhibits features which are closely spatially correlated with the crustal thickness, the mantle gravity map reveals mainly the gravitational signature of the uppermost mantle, which is superposed over a weaker (long-wavelength) signature of density heterogeneities distributed deeper in the mantle. In contrast to a relatively complex and segmented uppermost mantle structure of West Antarctica, the mantle gravity map confirmed a more uniform structure of the East Antarctic Craton. The most pronounced features in this gravity map are divergent tectonic margins along mid-oceanic ridges and continental rifts. Gravity lows at these locations indicate that a broad region of the West Antarctic Rift System continuously extends between the Atlantic-Indian and Pacific-Antarctic mid-oceanic ridges and it is possibly formed by two major fault segments. Gravity lows over the Transantarctic Mountains confirms their non-collisional origin. Additionally, more localized gravity lows closely coincide with known locations of hotspots and volcanic regions (Marie Byrd Land, Balleny Islands, Mt. Erebus). Gravity lows also suggest a possible hotspot under the South Orkney Islands. However, this finding has to be further verified.

Geologic Map and Map Database of Eastern Sonoma and Western Napa Counties, California

USGS Publications Warehouse

Graymer, R.W.; Brabb, E.E.; Jones, D.L.; Barnes, J.; Nicholson, R.S.; Stamski, R.E.

2007-01-01

Introduction This report contains a new 1:100,000-scale geologic map, derived from a set of geologic map databases (Arc-Info coverages) containing information at 1:62,500-scale resolution, and a new description of the geologic map units and structural relations in the map area. Prepared as part of the San Francisco Bay Region Mapping Project, the study area includes the north-central part of the San Francisco Bay region, and forms the final piece of the effort to generate new, digital geologic maps and map databases for an area which includes Alameda, Contra Costa, Marin, Napa, San Francisco, San Mateo, Santa Clara, Santa Cruz, Solano, and Sonoma Counties. Geologic mapping in Lake County in the north-central part of the map extent was not within the scope of the Project. The map and map database integrates both previously published reports and new geologic mapping and field checking by the authors (see Sources of Data index map on the map sheet or the Arc-Info coverage eswn-so and the textfile eswn-so.txt). This report contains new ideas about the geologic structures in the map area, including the active San Andreas Fault system, as well as the geologic units and their relations. Together, the map (or map database) and the unit descriptions in this report describe the composition, distribution, and orientation of geologic materials and structures within the study area at regional scale. Regional geologic information is important for analysis of earthquake shaking, liquifaction susceptibility, landslide susceptibility, engineering materials properties, mineral resources and hazards, as well as groundwater resources and hazards. These data also assist in answering questions about the geologic history and development of the California Coast Ranges.