Sample records for azimuthally dependent transport

  1. Transverse spin dependent azimuthal asymmetries at COMPASS

    E-print Network

    Bakur Parsamyan

    2013-01-29

    In semi-inclusive deep inelastic scattering of polarized leptons on a transversely polarized target eight target transverse spin-dependent azimuthal modulations are allowed. In the QCD parton model half of these asymmetries can be interpreted within the leading order approach and the other four are twist-three contributions. The first two leading twist asymmetries extracted by HERMES and COMPASS experiments are related: one to the transversity distribution and the Collins effect, the other to the Sivers distribution function. These results triggered a lot of interest in the past few years and allowed the first extractions of the transversity and the Sivers distribution functions of nucleon. The remaining six asymmetries were obtained by the COMPASS experiment using a 160 GeV/c longitudinally polarized muon beam and transversely polarized deuteron and proton targets. Here we review preliminary results from COMPASS proton data of 2007.

  2. Nuclear dependencies of azimuthal asymmetries in the Drell-Yan process

    NASA Astrophysics Data System (ADS)

    Chen, Long; Gao, Jian-hua; Liang, Zuo-tang

    2014-03-01

    We study nuclear dependencies of azimuthal asymmetries in the Drell-Yan lepton pair production in nucleon-nucleus collisions with polarized nucleons. We use the "maximal two-gluon correlation approximation," so that we can relate the transverse-momentum-dependent quark distribution in a nucleus to that in a nucleon by a convolution with a Gaussian broadening. We use the Gaussian ansatz for the transverse momentum dependence of such quark distribution functions and obtain the numerical results for the nuclear dependencies. These results show that the qT-integrated azimuthal asymmetries are suppressed.

  3. Azimuthal dependence in the gravity field induced by recent and past cryospheric forcings

    NASA Technical Reports Server (NTRS)

    Yuen, David A.; Gasperini, Paolo; Sabadini, Roberto; Boschi, Enzo

    1987-01-01

    Present-day glacial activities and the current variability of the Antarctic ice volume can cause variations in the long-wavelength gravity field as a consequence of transient viscoelastic responses in the mantle. The azimuthal dependence of the secular variations of the gravitational potential are studied and it is found that the nonaxisymmetric contributions are more important for recent glacial retreats than for Pleistocene deglaciation. Changes in land-based ice covering Antarctica can be detected by monitoring satellite orbits and their sensitivity to variations in gravitational harmonic for degree l greater than 3. Resonances in satellite orbits may be useful for detecting these azimuthally-dependent gravity signals.

  4. Charge-dependent azimuthal correlations from AuAu to UU collisions

    NASA Astrophysics Data System (ADS)

    Bloczynski, John; Huang, Xu-Guang; Zhang, Xilin; Liao, Jinfeng

    2015-07-01

    We study the charge-dependent azimuthal correlations in relativistic heavy ion collisions, as motivated by the search for the Chiral Magnetic Effect (CME) and the investigation of related background contributions. In particular we aim to understand how these correlations induced by various proposed effects evolve from collisions with AuAu system to that with UU system. To do that, we quantify the generation of magnetic field in UU collisions at RHIC energy and its azimuthal correlation with the matter geometry using event-by-event simulations. Taking the experimental data for charge-dependent azimuthal correlations from AuAu collisions and extrapolating to UU with reasonable assumptions, we examine the resulting correlations to be expected in UU collisions and compare them with recent STAR measurements. Based on such analysis we discuss the viability for explaining the data with a combination of the CME-like and flow-induced contributions.

  5. Saturated Fluctuations and Transport in Axial, Azimuthal Hybrid Hall Thruster Simulations

    NASA Astrophysics Data System (ADS)

    Dowdy, Caleb; Aley, Jacob; Fernandez, Eduardo

    2014-10-01

    Simulation studies of Hall thrusters aimed at describing the global domain typically employ hybrid schemes instead of more expensive kinetic approaches. Such simulations are generally in the radial and axial coordinates, assuming axisymmetry in order to circumvent azimuthal dynamics. Cross-field electron transport is enhanced (in an ad-hoc manner) in order to sustain the plasma and produce simulation profiles in semi-quantitative agreement with experimental measurements. In this work we present results from an axial/azimuthal hybrid fluid-PIC model of Hall thrusters that treats the azimuthal dynamics self-consistently, without employing ad-hoc transport parameters. Unlike previous simulation efforts with this model, the current work has succeeded at obtaining fully saturated states at high voltage, resolving the longest (breathing mode) timescales in the system. Equilibrium profiles and fluctuations predicted by the simulation will be presented. The latter are analyzed in terms of their frequency and propagation characteristics, as well as their contribution to transport. Linear stability theory is used to comment on the possible origin of the disturbances. Finally, the role of EXB flow shear on the potential regulation of fluctuation-induced electron transport is discussed. Caleb Dowdy, Jacob Aley and Eduardo Fernandez are supported by a grant from the II- VI Foundation.

  6. TRACING OUTFLOWS AND ACCRETION: A BIMODAL AZIMUTHAL DEPENDENCE OF Mg II ABSORPTION

    SciTech Connect

    Kacprzak, Glenn G. [Swinburne University of Technology, Victoria 3122 (Australia); Churchill, Christopher W.; Nielsen, Nikole M., E-mail: gkacprzak@astro.swin.edu.au [New Mexico State University, Las Cruces, NM 88003 (United States)

    2012-11-20

    We report a bimodality in the azimuthal angle distribution of gas around galaxies as traced by Mg II absorption: halo gas prefers to exist near the projected galaxy major and minor axes. The bimodality is demonstrated by computing the mean azimuthal angle probability distribution function using 88 spectroscopically confirmed Mg II-absorption-selected galaxies [W{sub r} (2796) {>=} 0.1 A] and 35 spectroscopically confirmed non-absorbing galaxies [W{sub r} (2796) < 0.1 A] imaged with Hubble Space Telescope and Sloan Digital Sky Survey. The azimuthal angle distribution for non-absorbers is flat, indicating no azimuthal preference for gas characterized by W{sub r} (2796) < 0.1 A. We find that blue star-forming galaxies clearly drive the bimodality while red passive galaxies may exhibit an excess along their major axis. These results are consistent with galaxy evolution scenarios where star-forming galaxies accrete new gas, forming new stars and producing winds, while red galaxies exist passively due to reduced gas reservoirs. We further compute an azimuthal angle dependent Mg II absorption covering fraction, which is enhanced by as much as 20%-30% along the major and minor axes. The W{sub r} (2796) distribution for gas along the major axis is likely skewed toward weaker Mg II absorption than for gas along the projected minor axis. These combined results are highly suggestive that the bimodality is driven by gas accreted along the galaxy major axis and outflowing along the galaxy minor axis. Adopting these assumptions, we find that the opening angle of outflows and inflows to be 100 Degree-Sign and 40 Degree-Sign , respectively. We find that the probability of detecting outflows is {approx}60%, implying that winds are more commonly observed.

  7. Tracing Outflows and Accretion: A Bimodal Azimuthal Dependence of Mg II Absorption

    NASA Astrophysics Data System (ADS)

    Kacprzak, Glenn G.; Churchill, Christopher W.; Nielsen, Nikole M.

    2012-11-01

    We report a bimodality in the azimuthal angle distribution of gas around galaxies as traced by Mg II absorption: halo gas prefers to exist near the projected galaxy major and minor axes. The bimodality is demonstrated by computing the mean azimuthal angle probability distribution function using 88 spectroscopically confirmed Mg II-absorption-selected galaxies [Wr (2796) >= 0.1 Å] and 35 spectroscopically confirmed non-absorbing galaxies [Wr (2796) < 0.1 Å] imaged with Hubble Space Telescope and Sloan Digital Sky Survey. The azimuthal angle distribution for non-absorbers is flat, indicating no azimuthal preference for gas characterized by Wr (2796) < 0.1 Å. We find that blue star-forming galaxies clearly drive the bimodality while red passive galaxies may exhibit an excess along their major axis. These results are consistent with galaxy evolution scenarios where star-forming galaxies accrete new gas, forming new stars and producing winds, while red galaxies exist passively due to reduced gas reservoirs. We further compute an azimuthal angle dependent Mg II absorption covering fraction, which is enhanced by as much as 20%-30% along the major and minor axes. The Wr (2796) distribution for gas along the major axis is likely skewed toward weaker Mg II absorption than for gas along the projected minor axis. These combined results are highly suggestive that the bimodality is driven by gas accreted along the galaxy major axis and outflowing along the galaxy minor axis. Adopting these assumptions, we find that the opening angle of outflows and inflows to be 100° and 40°, respectively. We find that the probability of detecting outflows is ~60%, implying that winds are more commonly observed.

  8. Hadronization Scheme Dependence of Long-Range Azimuthal Harmonics in High Energy p+A Reactions

    E-print Network

    Esposito, Angelo

    2015-01-01

    We compare the distortion effects of three popular final state hadronization schemes that modify the initial-state gluon azimuthal harmonic correlations in high energy p+A collisions. The three models considered are (1) LPH: local parton-hadron duality, (2) CPR: collinear parton-hadron resonance independent fragmenation, and (3) LUND: color string hadronization. Strong initial-state multi-gluon azimuthal correlations are generated using the non-abelian beam jet bremsstrahlung GLVB model, assuming a saturation scale Qsat = 2 GeV. Long-range final hadron pair elliptic and triangular harmonics are compared based on the three hadronization schemes. Our analysis shows that the hadron level harmonics are strongly hadronization scheme dependent in the low pT < 3 GeV domain.

  9. Hadronization Scheme Dependence of Long-Range Azimuthal Harmonics in High Energy p+A Reactions

    E-print Network

    Angelo Esposito; Miklos Gyulassy

    2015-05-14

    We compare the distortion effects of three popular final state hadronization schemes that modify the initial-state gluon azimuthal harmonic correlations in high energy p+A collisions. The three models considered are (1) LPH: local parton-hadron duality, (2) CPR: collinear parton-hadron resonance independent fragmenation, and (3) LUND: color string hadronization. Strong initial-state multi-gluon azimuthal correlations are generated using the non-abelian beam jet bremsstrahlung GLVB model, assuming a saturation scale Qsat = 2 GeV. Long-range final hadron pair elliptic and triangular harmonics are compared based on the three hadronization schemes. Our analysis shows that the hadron level harmonics are strongly hadronization scheme dependent in the low pT < 3 GeV domain.

  10. Azimuthal angle dependence of the Coulomb barrier parameters for the interaction between two deformed nuclei

    SciTech Connect

    Ismail, M.; Adel, A. [Physics Department, Faculty of Science, Cairo University, Giza (Egypt)

    2011-09-15

    The azimuthal angle ({phi}) dependence of the Coulomb barrier parameters (height V{sub b} and position R{sub b}) are studied in the framework of the double-folding model with the realistic M3Y nucleon-nucleon interaction. Different pairs of axially symmetric, deformed nuclei are considered. For the interaction between medium and heavy nuclei, the maximum percentage of {phi} dependence is studied as a function of relative orientations of the interacting nuclei. It appreciably increases as the values of the deformation parameters increase and is sensitive to the hexadecapole deformation. The smallest {phi} variation is found for the relative orientations {theta}{sub P}={theta}{sub T}=90 deg. The {phi} variation of the Coulomb barrier parameters, as calculated in the present paper, is completely different in both magnitude and behavior from those deduced in the widely used proximity approach.

  11. LETTER TO THE EDITOR: Quantitative description of the azimuthal dependence of the exchange bias effect

    NASA Astrophysics Data System (ADS)

    Radu, Florin; Westphalen, Andreas; Theis-Bröhl, Katharina; Zabel, Hartmut

    2006-01-01

    While the principal features of the exchange bias between a ferromagnet and an antiferromagnet are believed to be understood, a quantitative description is still lacking. We show that interface spin disorder is the main reason for the discrepancy of model calculations versus experimental results. Taking into account spin disorder at the interface between the ferromagnet and the antiferromagnet by modifying the well known Meiklejohn and Bean model, an almost perfect agreement can be reached. As an example this is demonstrated for the CoFe/IrMn exchange biased bilayer by analysing the azimuthal dependence of magnetic hysteresis loops from MOKE measurements. Both exchange bias and coercive fields for the complete 360° angular range are reproduced by our model.

  12. System size dependence of nuclear modification and azimuthal anisotropy of jet quenching

    NASA Astrophysics Data System (ADS)

    De, Somnath; Srivastava, Dinesh K.

    2012-01-01

    We investigate the system size dependence of jet quenching by analysing transverse momentum spectra of neutral pions in Au+Au and Cu+Cu collisions at \\sqrt{s_{\\textrm {NN}}} =200 GeV for different centralities. The fast partons are assumed to lose energy by radiating gluons as they traverse the plasma and undergo multiple collisions. The energy loss per collision, ?, is taken as proportional to E (where E is the energy of the parton), proportional to \\sqrt{E}, or a constant depending on whether the formation time of the gluon is less than the mean path, greater than the mean-free path but less than the path length, or greater than the path length of the partons, respectively. NLO pQCD is used to evaluate pion production by modifying the fragmentation function to account for the energy loss. We reproduce the nuclear modification factor RAA by treating ? as the only free parameter, depending on the centrality and the mechanism of energy loss. These values are seen to explain the nuclear modification of prompt photons caused by the energy lost by final state quarks before they fragment into photons. These also reproduce the azimuthal asymmetry of transverse momentum distribution for pions within a factor of 2 and for prompt photons in fair agreement with experimental data.

  13. A1. Synthetic surface wave phase velocities The azimuthal dependence of phase velocities were computed based on the perturbation

    E-print Network

    Ito, Garrett

    APPENDIX A1. Synthetic surface wave phase velocities The azimuthal dependence of phase velocitiessin4cos2sin2cos 2 1 , 4321 TATATATA U Tc , (1) where T is period, U is group velocity) and the displacement eigenfunctions of the isotropic model. Phase velocity values were calculated for Rayleigh wave

  14. Azimuth-dependent Auger neutralization of He{sup +} on Ag(111) and (110) surfaces

    SciTech Connect

    Valdes, Diego; Monreal, R. C. [Departamento de Fisica Teorica de la Materia Condensada, Universidad Autonoma de Madrid, E-28049 Madrid (Spain); Blanco, J. M. [Departamento de Fisica Teorica de la Materia Condensada, Universidad Autonoma de Madrid, E-28049 Madrid (Spain); European Space Astronomy Centre, ESAC-ESA, Ingenieria y Servicios Aeroespaciales (Spain); Esaulov, V. A. [Laboratoire des Collisions Atomiques et Moleculaires, Universite Paris Sud, 91405 Orsay (France)

    2007-04-15

    We present a detailed theoretical analysis of the role played by s and d electrons in Auger neutralization processes of He{sup +} at Ag(111) and Ag(110) surfaces. We calculate crystal-lattice-site Auger neutralization rates as a function of the perpendicular distance between ions and surfaces. We find that the rate is very insensitive to the lateral position for large values of the perpendicular distance because the contribution of the delocalized s electrons dominates in this case. In contrast, the contribution of d electrons dominates at short perpendicular distances and the strong spatial localization of these electrons causes a similar strong dependence of the Auger rate with lateral position. We perform molecular dynamic simulations of scattered ion trajectories, which, used together with the Auger neutralization rates, allow us to obtain the theoretical ion fraction that we compare with our measurements. This parameter-free theory is able to reproduce the magnitude of the ion survival probability and its dependence with the azimuthal angle of incidence for both surfaces of Ag, thus showing the important role played by localized electrons in Auger neutralization of He.

  15. Pennsylvania salient of the Appalachians: A two-azimuth transport model based on new compilations of Piedmont data

    NASA Astrophysics Data System (ADS)

    Wise, Donald U.

    2004-09-01

    New compilations of geometry and tectonic transport in the Pennsylvania salient suggest that these features continue uninterrupted from the Piedmont through the Valley and Ridge provinces. These data are the basis for a new two-azimuth transport model for origin of the curvature. Edge geometry of an Eocambrian craton and a thickened stratigraphy acted as templates for Alleghanian regional décollement, first as Reading Prong ˜N35°W motion, followed by ˜N68°W Blue Ridge motion. Both displacements involved some drag rotation and overprinting in a central zone. This model avoids the problem of minimal tangential stretching, explains the anthracite basins as trailing-edge graben and basin structures against the autochthonous Pocono Plateau, and produces the Nittany-Juniata culmination as an overprinted pileup of duplexes in the central zone. The model of detachment followed by changing azimuth of motion of a megadécollement sheet may apply to other salients throughout the world.

  16. Nuclear-mass dependence of azimuthal beam-helicity and beam-charge asymmetries in deeply virtual Compton scattering

    SciTech Connect

    Airapetian, A. [Physikalisches Institut, Universitaet Giessen, D-35392 Giessen (Germany); Randall Laboratory of Physics, University of Michigan, Ann Arbor, Michigan 48109-1040 (United States); Akopov, N.; Avakian, R.; Avetissian, A.; Elbakian, G.; Gharibyan, V.; Karyan, G.; Marukyan, H.; Movsisyan, A.; Taroian, S. [Yerevan Physics Institute, 375036 Yerevan (Armenia); Akopov, Z.; Avetisyan, E.; Borissov, A.; Hartig, M.; Holler, Y.; Rostomyan, A.; Schueler, K. P.; Varanda, M.; Ye, Z.; Zihlmann, B. [DESY, D-22603 Hamburg (Germany)

    2010-03-15

    The nuclear-mass dependence of azimuthal cross-section asymmetries with respect to charge and longitudinal polarization of the lepton beam is studied for hard exclusive electroproduction of real photons. The observed beam-charge and beam-helicity asymmetries are attributed to the interference between the Bethe-Heitler and the deeply virtual Compton scattering processes. For various nuclei, the asymmetries are extracted for both coherent and incoherent-enriched regions, which involve different (combinations of) generalized parton distributions. For both regions, the asymmetries are compared to those for a free proton, and no nuclear-mass dependence is found.

  17. Nuclear-mass dependence of azimuthal beam-helicity and beam-charge asymmetries in deeply virtual Compton scattering

    NASA Astrophysics Data System (ADS)

    Airapetian, A.; Akopov, N.; Akopov, Z.; Amarian, M.; Aschenauer, E. C.; Augustyniak, W.; Avakian, R.; Avetissian, A.; Avetisyan, E.; Ball, B.; Belostotski, S.; Bianchi, N.; Blok, H. P.; Böttcher, H.; Borissov, A.; Bowles, J.; Bryzgalov, V.; Burns, J.; Capiluppi, M.; Capitani, G. P.; Cisbani, E.; Ciullo, G.; Contalbrigo, M.; Dalpiaz, P. F.; Deconinck, W.; Leo, R. De; Nardo, L. De; Sanctis, E. De; Diefenthaler, M.; Nezza, P. Di; Düren, M.; Ehrenfried, M.; Elbakian, G.; Ellinghaus, F.; Fabbri, R.; Fantoni, A.; Felawka, L.; Frullani, S.; Gabbert, D.; Gapienko, G.; Gapienko, V.; Garibaldi, F.; Gavrilov, G.; Gharibyan, V.; Giordano, F.; Gliske, S.; Guler, H.; Guzey, V.; Haan, S.; Hadjidakis, C.; Hartig, M.; Hasch, D.; Hill, G.; Hillenbrand, A.; Hoek, M.; Holler, Y.; Hristova, I.; Imazu, Y.; Ivanilov, A.; Jackson, H. E.; Jo, H. S.; Joosten, S.; Kaiser, R.; Karyan, G.; Keri, T.; Kinney, E.; Kisselev, A.; Korotkov, V.; Kozlov, V.; Kravchenko, P.; Lagamba, L.; Lamb, R.; Lapikás, L.; Lehmann, I.; Lenisa, P.; López Ruiz, A.; Lorenzon, W.; Lu, X.-G.; Lu, X.-R.; Ma, B.-Q.; Mahon, D.; Makins, N. C. R.; Manaenkov, S. I.; Manfré, L.; Mao, Y.; Marianski, B.; de La Ossa, A. Martinez; Marukyan, H.; Miller, C. A.; Miyachi, Y.; Movsisyan, A.; Muccifora, V.; Murray, M.; Mussgiller, A.; Nappi, E.; Naryshkin, Y.; Nass, A.; Negodaev, M.; Nowak, W.-D.; Pappalardo, L. L.; Perez-Benito, R.; Raithel, M.; Reimer, P. E.; Reolon, A. R.; Riedl, C.; Rith, K.; Rosner, G.; Rostomyan, A.; Rubin, J.; Ryckbosch, D.; Salomatin, Y.; Schäfer, A.; Schnell, G.; Schüler, K. P.; Shanidze, R.; Shibata, T.-A.; Shutov, V.; Stancari, M.; Statera, M.; Steffens, E.; Steijger, J. J. M.; Stewart, J.; Stinzing, F.; Taroian, S.; Terkulov, A.; Trzcinski, A.; Tytgat, M.; Vandenbroucke, A.; Haarlem, Y. Van; Hulse, C. Van; Varanda, M.; Veretennikov, D.; Vikhrov, V.; Vilardi, I.; Wang, S.; Yaschenko, S.; Ye, H.; Ye, Z.; Yu, W.; Zeiler, D.; Zihlmann, B.; Zupranski, P.; sHERMES Collaboration

    2010-03-01

    The nuclear-mass dependence of azimuthal cross-section asymmetries with respect to charge and longitudinal polarization of the lepton beam is studied for hard exclusive electroproduction of real photons. The observed beam-charge and beam-helicity asymmetries are attributed to the interference between the Bethe-Heitler and the deeply virtual Compton scattering processes. For various nuclei, the asymmetries are extracted for both coherent and incoherent-enriched regions, which involve different (combinations of) generalized parton distributions. For both regions, the asymmetries are compared to those for a free proton, and no nuclear-mass dependence is found.

  18. Dependence of planar alignment layer upon enhancement of azimuthal anchoring energy by reactive mesogens

    NASA Astrophysics Data System (ADS)

    Kim, Youngsik; Lee, You-Jin; Baek, Ji-Ho; Yu, Chang-Jae; Kim, Jae-Hoon

    2015-01-01

    Reactive mesogens (RMs) can enhance the azimuthal anchoring energy of planar alignment layers used in liquid crystal (LC) devices; herein, we studied the interactions between the RMs and the planar alignment material that determine whether this enhancement can occur. Two alignment-layer materials were studied: polyamic acid (PA) and polyimide (PI). The addition of RMs to the PI-type alignment layer was effective in enhancing the azimuthal anchoring energy, whereas the addition of RMs to the PA-type alignment layer had little effect. Surface analysis revealed that the RMs adhered well to the PI-type alignment surface only; in the resulting cell, the presence of the RMs enhanced both the rise and decay times in fringe field switching (FFS)-mode operation.

  19. Centrality Dependence of Azimuthal Anisotropy of Strange Hadrons in 200 GeV Au+Au Collisions

    E-print Network

    M. Oldenburg; for the STAR Collaboration

    2006-07-18

    Measurements of azimuthal anisotropy for strange and multi-strange hadrons are presented for the first time in their centrality dependence. The high statistics results of v2(pT) allow for a more detailed comparison to hydrodynamical model calculations. Number-of-constituent-quark scaling was tested for different centrality classes separately. Higher order anisotropies like v4(pT) are measured for multi-strange hadrons. While we observe agreement between measured data and models a deeper understanding and refinement of the models seem to be necessary in order to fully understand the details of the data.

  20. Multiplicity dependence of two-particle azimuthal correlations in pp collisions at the LHC

    NASA Astrophysics Data System (ADS)

    Abelev, B.; Adam, J.; Adamová, D.; Adare, A. M.; Aggarwal, M. M.; Aglieri Rinella, G.; Agnello, M.; Agocs, A. G.; Agostinelli, A.; Ahammed, Z.; Ahmad Masoodi, A.; Ahmad, N.; Ahmed, I.; Ahn, S. U.; Ahn, S. A.; Aimo, I.; Ajaz, M.; Akindinov, A.; Aleksandrov, D.; Alessandro, B.; Alexandre, D.; Alici, A.; Alkin, A.; Alme, J.; Alt, T.; Altini, V.; Altinpinar, S.; Altsybeev, I.; Andrei, C.; Andronic, A.; Anguelov, V.; Anielski, J.; Anson, C.; Anti?i?, T.; Antinori, F.; Antonioli, P.; Aphecetche, L.; Appelshäuser, H.; Arbor, N.; Arcelli, S.; Arend, A.; Armesto, N.; Arnaldi, R.; Aronsson, T.; Arsene, I. C.; Arslandok, M.; Asryan, A.; Augustinus, A.; Averbeck, R.; Awes, T. C.; Äystö, J.; Azmi, M. D.; Bach, M.; Badalà, A.; Baek, Y. W.; Bailhache, R.; Bala, R.; Baldisseri, A.; Baltasar Dos Santos Pedrosa, F.; Bán, J.; Baral, R. C.; Barbera, R.; Barile, F.; Barnaföldi, G. G.; Barnby, L. S.; Barret, V.; Bartke, J.; Basile, M.; Bastid, N.; Basu, S.; Bathen, B.; Batigne, G.; Batyunya, B.; Batzing, P. C.; Baumann, C.; Bearden, I. G.; Beck, H.; Behera, N. K.; Belikov, I.; Bellini, F.; Bellwied, R.; Belmont-Moreno, E.; Bencedi, G.; Beole, S.; Berceanu, I.; Bercuci, A.; Berdanikov, Y.; Berenyi, D.; Bergognon, A. A. E.; Bertens, R. A.; Berzano, D.; Betev, L.; Bhasin, A.; Bhati, A. K.; Bhom, J.; Bianchi, L.; Bianchi, N.; Bianchin, C.; Biel?ík, J.; Biel?íková, J.; Bilandzic, A.; Bjelogrlic, S.; Blanco, F.; Blanco, F.; Blau, D.; Blume, C.; Boccioli, M.; Bock, F.; Böttger, S.; Bogdanov, A.; Bøggild, H.; Bogolyubsky, M.; Boldizsár, L.; Bombara, M.; Book, J.; Borel, H.; Borissov, A.; Bornschein, J.; Bossú, F.; Botje, M.; Botta, E.; Braidot, E.; Braun-Munzinger, P.; Bregant, M.; Breitner, T.; Broker, T. A.; Browning, T. A.; Broz, M.; Brun, R.; Bruna, E.; Bruno, G. E.; Budnikov, D.; Buesching, H.; Bufalino, S.; Buncic, P.; Busch, O.; Buthelezi, Z.; Caffarri, D.; Cai, X.; Caines, H.; Caliva, A.; Calvo Villar, E.; Camerini, P.; Canoa Roman, V.; Cara Romeo, G.; Carena, F.; Carena, W.; Carlin Filho, N.; Carminati, F.; Casanova Díaz, A.; Castillo Castellanos, J.; Castillo Hernandez, J. F.; Casula, E. A. R.; Catanescu, V.; Cavicchioli, C.; Ceballos Sanchez, C.; Cepila, J.; Cerello, P.; Chang, B.; Chapeland, S.; Charvet, J. L.; Chattopadhyay, S.; Chattopadhyay, S.; Cherney, M.; Cheshkov, C.; Cheynis, B.; Chibante Barroso, V.; Chinellato, D. D.; Chochula, P.; Chojnacki, M.; Choudhury, S.; Christakoglou, P.; Christensen, C. H.; Christiansen, P.; Chujo, T.; Chung, S. U.; Cicalo, C.; Cifarelli, L.; Cindolo, F.; Cleymans, J.; Colamaria, F.; Colella, D.; Collu, A.; Conesa Balbastre, G.; Conesa del Valle, Z.; Connors, M. E.; Contin, G.; Contreras, J. G.; Cormier, T. M.; Corrales Morales, Y.; Cortese, P.; Cortés Maldonado, I.; Cosentino, M. R.; Costa, F.; Cotallo, M. E.; Crescio, E.; Crochet, P.; Cruz Alaniz, E.; Cruz Albino, R.; Cuautle, E.; Cunqueiro, L.; Czopowicz, T. R.; Dainese, A.; Dang, R.; Danu, A.; Das, I.; Das, S.; Das, D.; Das, K.; Dash, S.; Dash, A.; De, S.; de Barros, G. O. V.; De Caro, A.; de Cataldo, G.; de Cuveland, J.; De Falco, A.; De Gruttola, D.; Delagrange, H.; Deloff, A.; De Marco, N.; Dénes, E.; De Pasquale, S.; Deppman, A.; Erasmo, G. D.; de Rooij, R.; Diaz Corchero, M. A.; Di Bari, D.; Dietel, T.; Di Giglio, C.; Di Liberto, S.; Di Mauro, A.; Di Nezza, P.; Divià, R.; Djuvsland, Ø.; Dobrin, A.; Dobrowolski, T.; Dönigus, B.; Dordic, O.; Dubey, A. K.; Dubla, A.; Ducroux, L.; Dupieux, P.; Dutta Majumdar, A. K.; Elia, D.; Elwood, B. G.; Emschermann, D.; Engel, H.; Erazmus, B.; Erdal, H. A.; Eschweiler, D.; Espagnon, B.; Estienne, M.; Esumi, S.; Evans, D.; Evdokimov, S.; Eyyubova, G.; Fabris, D.; Faivre, J.; Falchieri, D.; Fantoni, A.; Fasel, M.; Fehlker, D.; Feldkamp, L.; Felea, D.; Feliciello, A.; Fenton-Olsen, B.; Feofilov, G.; Fernández Téllez, A.; Ferretti, A.; Festanti, A.; Figiel, J.; Figueredo, M. A. S.; Filchagin, S.; Finogeev, D.; Fionda, F. M.; Fiore, E. M.; Floratos, E.; Floris, M.; Foertsch, S.; Foka, P.; Fokin, S.; Fragiacomo, E.; Francescon, A.; Frankenfeld, U.; Fuchs, U.; Furget, C.; Fusco Girard, M.; Gaardhøje, J. J.; Gagliardi, M.; Gago, A.; Gallio, M.; Gangadharan, D. R.; Ganoti, P.; Garabatos, C.; Garcia-Solis, E.; Gargiulo, C.; Garishvili, I.; Gerhard, J.; Germain, M.; Gheata, M.; Gheata, A.; Ghidini, B.; Ghosh, P.; Gianotti, P.; Giubellino, P.; Gladysz-Dziadus, E.; Glässel, P.; Goerlich, L.; Gomez, R.; Ferreiro, E. G.; González-Zamora, P.; Gorbunov, S.; Goswami, A.; Gotovac, S.; Graczykowski, L. K.; Grajcarek, R.; Grelli, A.; Grigoras, A.; Grigoras, C.; Grigoriev, V.; Grigoryan, A.; Grigoryan, S.; Grinyov, B.; Grion, N.; Gros, P.; Grosse-Oetringhaus, J. F.; Grossiord, J.-Y.; Grosso, R.; Guber, F.; Guernane, R.; Guerzoni, B.; Guilbaud, M.

    2013-09-01

    We present the measurements of particle pair yields per trigger particle obtained from di-hadron azimuthal correlations in pp collisions at = 0 .9, 2.76, and 7 TeV recorded with the ALICE detector. The yields are studied as a function of the charged particle multiplicity. Taken together with the single particle yields the pair yields provide information about parton fragmentation at low transverse momenta, as well as on the contribution of multiple parton interactions to particle production. Data are compared to calculations using the PYTHIA6, PYTHIA8, and PHOJET event generators. [Figure not available: see fulltext.

  1. Instabilities of rotational flows in azimuthal magnetic fields of arbitrary radial dependence

    NASA Astrophysics Data System (ADS)

    Kirillov, Oleg N.; Stefani, Frank; Fukumoto, Yasuhide

    2014-06-01

    Using the Wentzel-Kramers-Brillouin (WKB) approximation we perform a linear stability analysis for a rotational flow of a viscous and electrically conducting fluid in an external azimuthal magnetic field that has an arbitrary radial profile B?(R). In the inductionless approximation, we find the growth rate of the three-dimensional perturbation in a closed form and demonstrate in particular that it can be positive when the velocity profile is Keplerian and the magnetic field profile is slightly shallower than R-1.

  2. Longitudinal, Azimuthal and Multiplicity Dependences of Mean Transverse Momentum and Transverse Momentum Correlations in ?+p and K+p Collisions at 250GeV/c

    NASA Astrophysics Data System (ADS)

    Yanping, Huang; Yuanfang, Wu

    2006-04-01

    Rapidity, azimuthal and multiplicity dependence of inclusive mean transverse momentum and transverse momentum correlation is studied in ?+p and K+p collisions at 250 GeV/c. It is found for the first time that rapidity dependence of two-particle transverse momentum correlations is different from those of inclusive mean transverse momentum but both have similar multiplicity dependence. In particular, the transverse momentum correlation is boost-invariant. The strong azimuthal dependence of transverse momentum correlation comes from the constraint of energy-momentum conservation. The results are compared with those from the PYTHIA Monte Carlo generator. The similarities and differences with those from current heavy ion experiments are discussed.

  3. Dependence of enhanced asymmetry-induced transport on collision frequency

    NASA Astrophysics Data System (ADS)

    Eggleston, D. L.

    2014-07-01

    A single-particle code with collisional effects is used to study how asymmetry-induced radial transport in a non-neutral plasma depends on collision frequency. For asymmetries of the form ?1(r) cos(kz) cos(?t-l?), two sources for the transport have been identified: resonant particles and axially trapped particles. The simulation shows that this latter type, which occurs near the radius where ? matches the azimuthal rotation frequency ?R, is usually dominant at low collision frequency ? but becomes negligible at higher ?. This behavior can be understood by noting that axially trapped particles have a lower trapping frequency than resonant particles. In the low ? (banana) regime, the radial oscillations have amplitude ?r ? vr/?T, so axially trapped particles dominate, and the transport may even exceed the resonant particle plateau regime level. As ? increases, collisions start to interrupt the slower axially trapped particle oscillations, while the resonant particles are still in the banana regime, so the axially trapped particle contribution to the transport decreases. At the largest ? values, axially trapped particle transport is negligible and the observed diffusion coefficient matches that given by plateau regime resonant particle theory. Heuristic models based on these considerations give reasonable agreement with the observed scaling laws for the value of the collision frequency where axially trapped particle transport starts to decrease and for the enhancement of the diffusion coefficient produced by axially trapped particles.

  4. Dependence of enhanced asymmetry-induced transport on collision frequency

    SciTech Connect

    Eggleston, D. L. [Occidental College, Physics Department, Los Angeles, California 90041 (United States)

    2014-07-15

    A single-particle code with collisional effects is used to study how asymmetry-induced radial transport in a non-neutral plasma depends on collision frequency. For asymmetries of the form ?{sub 1}(r)?cos(kz)?cos(?t?l?), two sources for the transport have been identified: resonant particles and axially trapped particles. The simulation shows that this latter type, which occurs near the radius where ? matches the azimuthal rotation frequency ?{sub R}, is usually dominant at low collision frequency ? but becomes negligible at higher ?. This behavior can be understood by noting that axially trapped particles have a lower trapping frequency than resonant particles. In the low ? (banana) regime, the radial oscillations have amplitude ?r???v{sub r}/?{sub T}, so axially trapped particles dominate, and the transport may even exceed the resonant particle plateau regime level. As ? increases, collisions start to interrupt the slower axially trapped particle oscillations, while the resonant particles are still in the banana regime, so the axially trapped particle contribution to the transport decreases. At the largest ? values, axially trapped particle transport is negligible and the observed diffusion coefficient matches that given by plateau regime resonant particle theory. Heuristic models based on these considerations give reasonable agreement with the observed scaling laws for the value of the collision frequency where axially trapped particle transport starts to decrease and for the enhancement of the diffusion coefficient produced by axially trapped particles.

  5. Two-charge-particle azimuthal correlations and the azimuthal balance function in RQMD and AMPT

    NASA Astrophysics Data System (ADS)

    Yuanfang, Wu; Yanping, Huang

    2007-08-01

    Two-charge-particle azimuthal correlations (TCPAC) and the azimuthal charge balance function (ACBF) are compared with anisotropic flow by using transport models, RQMD and AMPT. In these two models, TCPAC has the same centrality dependence as anisotropic flow. The momentum conservation contributes only back-to-back correlations in TCPAC, which are well separated from small angle correlations caused by anisotropic transverse momentum distribution, while the centrality dependence of ACBF is different from those of anisotropic flow and TCPAC. This indicates that ACBF cannot be used as another presentation of anisotropic flow, as expected from thermal models.

  6. System Size Dependence of Azimuthal Correlations in Relativistic Heavy Ion Collisions

    E-print Network

    Wolf G. Holzmann; for the PHENIX Collaboration

    2006-08-17

    Systematic comparisons of jet pair correlations obtained in Cu+Cu and Au+Au collisions at $\\sqrt{s_{NN}}=$200 GeV are presented. The measured jet-pair distributions for both systems, show strong modification of the away-side jet. For the same number of participating nucleons, the modification does not show a strong dependence on the collision system. It is suggested that such comparisons can provide important constraints for models which predict specific path length dependent jet modification effects.

  7. Rapidity, azimuthal, and multiplicity dependence of mean transverse momentum and transverse momentum correlations in ?+p and K+p collisions in s=22GeV

    NASA Astrophysics Data System (ADS)

    Atayan, M. R.; Yuting, Bai; de Wolf, E. A.; Endler, A. M. F.; Jinghua, Fu; Gulkanyan, H.; Hakobyan, R.; Yanping, Huang; Kittel, W.; Lianshou, Liu; Zhiming, Li; Metreveli, Z. V.; Smirnova, L. N.; Tikhonova, L. A.; Tomaradze, A. G.; Yuanfang, Wu; Zotkin, S. A.

    2006-04-01

    Rapidity, azimuthal and multiplicity dependence of mean transverse momentum and transverse momentum correlations of charged particles is studied in ?+p and K+p collisions at 250GeV/c incident beam momentum. For the first time, it is found that the rapidity dependence of the two-particle transverse momentum correlation is different from that of the mean transverse momentum, but both have similar multiplicity dependence. In particular, the transverse momentum correlations are boost invariant. This is similar to the recently found boost invariance of the charge balance function. A strong azimuthal dependence of the transverse momentum correlations originates from the constraint of energy-momentum conservation. The results are compared with those from the PYTHIA Monte Carlo generator. The similarities to and differences with the results from current heavy ion experiments are discussed.

  8. Asymmetry-Induced Transport with Azimuthal Perturbations at the Trapping Separatrix

    NASA Astrophysics Data System (ADS)

    Kabantsev, A. A.; Tsidulko, Yu. A.; Driscoll, C. F.

    2008-11-01

    Our experiments show that weak multipolar perturbations added to a trapping separatrix have large effects on asymmetry-induced transport and plasma wave damping, as suggested by recent theoretical models. Here, the pure electron plasma columns have a controlled trapping separatrix created by an applied ?-symmetric wall ``squeeze'' voltage, and a controlled overall asymmetry such as magnetic tilt. Breaking the ?-symmetry of the separatrix by adding multipolar potential perturbations ?m causes large and easily characterized effects for a variety of asymmetry-induced dissipative processes. For example, the measured bulk expansion rate ?P is a function of the angle ?? between the magnetic tilt and the multipolar separatrix perturbation. This function is the sum of phase-constant (c) and phase-variable ( ?) parts, i.e., ?P= ?c+ ??(2 ??). For dipole or quadrupole (m , 2 ) perturbations ?c ??, so ?P 2 ??2?( ??); and for higher (m ,4... ) perturbations one finds ???0, so the ?P enhancement is phase-independent. Moreover, the two parts scale differently with magnetic field B, possibly explaining the puzzling B-1.4 scalings observed experimentally. D.H.E. Dubin and Yu.A. Tsidulko, adjacent poster

  9. Beyond Collins and Sivers: further measurements of the target transverse spin-dependent azimuthal asymmetries in semi-inclusive DIS from COMPASS

    E-print Network

    Aram Kotzinian

    2007-05-16

    In semi-inclusive DIS of polarized leptons on a transversely polarized target eight azimuthal modulations appear in the cross-section. Within QCD parton model four azimuthal asymmetries can be interpreted at leading order, two of them being the already measured Collins and Sivers asymmetries. The other two leading twist asymmetries, related to different transverse momentum dependent quark distribution functions, and also additional four asymmetries which can be interpreted as twist-three contributions have been measured for the first time at COMPASS, using a 160 GeV/c longitudinally polarized ($P_{beam}\\simeq -0.8$) muon beam and a transversely polarized $^6LiD$ target. We present here the preliminary results from the 2002-2004 data.

  10. Observation of Transverse Spin-Dependent Azimuthal Correlations of Charged Pion Pairs in $p^\\uparrow+p$ at $\\sqrt{s}=200$ GeV

    E-print Network

    STAR Collaboration; L. Adamczyk; J. K. Adkins; G. Agakishiev; M. M. Aggarwal; Z. Ahammed; I. Alekseev; J. Alford; A. Aparin; D. Arkhipkin; E. C. Aschenauer; G. S. Averichev; A. Banerjee; R. Bellwied; A. Bhasin; A. K. Bhati; P. Bhattarai; J. Bielcik; J. Bielcikova; L. C. Bland; I. G. Bordyuzhin; J. Bouchet; A. V. Brandin; I. Bunzarov; T. P. Burton; J. Butterworth; H. Caines; M. Calder'on de la Barca S'anchez; J. M. Campbell; D. Cebra; M. C. Cervantes; I. Chakaberia; P. Chaloupka; Z. Chang; S. Chattopadhyay; J. H. Chen; X. Chen; J. Cheng; M. Cherney; W. Christie; G. Contin; H. J. Crawford; S. Das; L. C. De Silva; R. R. Debbe; T. G. Dedovich; J. Deng; A. A. Derevschikov; B. di Ruzza; L. Didenko; C. Dilks; X. Dong; J. L. Drachenberg; J. E. Draper; C. M. Du; L. E. Dunkelberger; J. C. Dunlop; L. G. Efimov; J. Engelage; G. Eppley; R. Esha; O. Evdokimov; O. Eyser; R. Fatemi; S. Fazio; P. Federic; J. Fedorisin; Z. Feng; P. Filip; Y. Fisyak; C. E. Flores; L. Fulek; C. A. Gagliardi; D. Garand; F. Geurts; A. Gibson; M. Girard; L. Greiner; D. Grosnick; D. S. Gunarathne; Y. Guo; S. Gupta; A. Gupta; W. Guryn; A. Hamad; A. Hamed; R. Haque; J. W. Harris; L. He; S. Heppelmann; S. Heppelmann; A. Hirsch; G. W. Hoffmann; D. J. Hofman; S. Horvat; B. Huang; X. Huang; H. Z. Huang; P. Huck; T. J. Humanic; G. Igo; W. W. Jacobs; H. Jang; K. Jiang; E. G. Judd; S. Kabana; D. Kalinkin; K. Kang; K. Kauder; H. W. Ke; D. Keane; A. Kechechyan; Z. H. Khan; D. P. Kikola; I. Kisel; A. Kisiel; L. Kochenda; D. D. Koetke; T. Kollegger; L. K. Kosarzewski; A. F. Kraishan; P. Kravtsov; K. Krueger; I. Kulakov; L. Kumar; R. A. Kycia; M. A. C. Lamont; J. M. Landgraf; K. D. Landry; J. Lauret; A. Lebedev; R. Lednicky; J. H. Lee; X. Li; C. Li; W. Li; Z. M. Li; Y. Li; X. Li; M. A. Lisa; F. Liu; T. Ljubicic; W. J. Llope; M. Lomnitz; R. S. Longacre; X. Luo; Y. G. Ma; G. L. Ma; L. Ma; R. Ma; N. Magdy; R. Majka; A. Manion; S. Margetis; C. Markert; H. Masui; H. S. Matis; D. McDonald; K. Meehan; N. G. Minaev; S. Mioduszewski; B. Mohanty; M. M. Mondal; D. Morozov; M. K. Mustafa; B. K. Nandi; Md. Nasim; T. K. Nayak; G. Nigmatkulov; L. V. Nogach; S. Y. Noh; J. Novak; S. B. Nurushev; G. Odyniec; A. Ogawa; K. Oh; V. Okorokov; D. Olvitt Jr.; B. S. Page; R. Pak; Y. X. Pan; Y. Pandit; Y. Panebratsev; B. Pawlik; H. Pei; C. Perkins; A. Peterson; P. Pile; M. Planinic; J. Pluta; N. Poljak; K. Poniatowska; J. Porter; M. Posik; A. M. Poskanzer; N. K. Pruthi; J. Putschke; H. Qiu; A. Quintero; S. Ramachandran; R. Raniwala; S. Raniwala; R. L. Ray; H. G. Ritter; J. B. Roberts; O. V. Rogachevskiy; J. L. Romero; A. Roy; L. Ruan; J. Rusnak; O. Rusnakova; N. R. Sahoo; P. K. Sahu; I. Sakrejda; S. Salur; J. Sandweiss; A. Sarkar; J. Schambach; R. P. Scharenberg; A. M. Schmah; W. B. Schmidke; N. Schmitz; J. Seger; P. Seyboth; N. Shah; E. Shahaliev; P. V. Shanmuganathan; M. Shao; M. K. Sharma; B. Sharma; W. Q. Shen; S. S. Shi; Q. Y. Shou; E. P. Sichtermann; R. Sikora; M. Simko; M. J. Skoby; D. Smirnov; N. Smirnov; L. Song; P. Sorensen; H. M. Spinka; B. Srivastava; T. D. S. Stanislaus; M. Stepanov; R. Stock; M. Strikhanov; B. Stringfellow; M. Sumbera; B. Summa; X. Sun; Z. Sun; X. M. Sun; Y. Sun; B. Surrow; N. Svirida; M. A. Szelezniak; A. H. Tang; Z. Tang; T. Tarnowsky; A. N. Tawfik; J. H. Thomas; A. R. Timmins; D. Tlusty; M. Tokarev; S. Trentalange; R. E. Tribble; P. Tribedy; S. K. Tripathy; B. A. Trzeciak; O. D. Tsai; T. Ullrich; D. G. Underwood; I. Upsal; G. Van Buren; G. van Nieuwenhuizen; M. Vandenbroucke; R. Varma; A. N. Vasiliev; R. Vertesi; F. Videbæk; Y. P. Viyogi; S. Vokal; S. A. Voloshin; A. Vossen; G. Wang; Y. Wang; F. Wang; Y. Wang; H. Wang; J. S. Wang; J. C. Webb; G. Webb; L. Wen; G. D. Westfall; H. Wieman; S. W. Wissink; R. Witt; Y. F. Wu; Z. G. Xiao; W. Xie; K. Xin; Q. H. Xu; Z. Xu; H. Xu; N. Xu; Y. F. Xu; Q. Yang; Y. Yang; S. Yang; Y. Yang; C. Yang; Z. Ye; P. Yepes; L. Yi; K. Yip; I. -K. Yoo; N. Yu; H. Zbroszczyk; W. Zha; X. P. Zhang; J. Zhang; Y. Zhang; J. Zhang; J. B. Zhang; S. Zhang; Z. Zhang; J. Zhao; C. Zhong; L. Zhou; X. Zhu; Y. Zoulkarneeva; M. Zyzak

    2015-04-01

    We report the observation of transverse polarization-dependent azimuthal correlations in charged pion pair production with the STAR experiment in $p^\\uparrow+p$ collisions at RHIC. These correlations directly probe quark transversity distributions. We measure signals in excess of five standard deviations at high transverse momenta, at high pseudorapidities eta>0.5, and for pair masses around the mass of the rho-meson. This is the first direct transversity measurement in p+p collisions. Comparing the results to data from lepton-nucleon scattering will test the universality of these spin-dependent quantities.

  11. Measurement of the Azimuthal Angle Dependence of Inclusive Jet Yields in Pb + Pb Collisions at ?s[subscript NN] = 2.76??TeV with the ATLAS Detector

    E-print Network

    Taylor, Frank E.

    Measurements of the variation of inclusive jet suppression as a function of relative azimuthal angle, ??, with respect to the elliptic event plane provide insight into the path-length dependence of jet quenching. ATLAS has ...

  12. Gravity-dependent transport in industrial processes

    NASA Technical Reports Server (NTRS)

    Ostrach, Simon; Kamotani, Yasuhiro

    1994-01-01

    Gravity-dependent transport phenomena in various industrial processes are investigated in order to address a broader range of microgravity phenomena and to develop new applications of microgravity. A number of important topics are identified and analyzed in detail. The present article describes results on coating flow, zeolite growth, and rotating electrochemical system.

  13. Observation of charge-dependent azimuthal correlations and possible local strong parity violation in heavy-ion collisions

    Microsoft Academic Search

    Sergei Voloshin; M. M. Aggarwal; Z. Ahammed; A. V. Alakhverdyants; B. D. Anderson; D. Arkhipkin; G. S. Averichev; J. Balewski; O. Barannikova; L. S. Barnby; S. Baumgart; D. R. Beavis; R. Bellwied; F. Benedosso; M. J. Betancourt; R. R. Betts; A. Bhasin; A. K. Bhati; H. Bichsel; J. Bielcikova; B. Biritz; L. C. Bland; I. Bnzarov; B. E. Bonner; J. Bouchet; E. Braidot; A. V. Brandin; A. Bridgeman; E. Bruna; S. Bueltmann; T. P. Burton; X. Z. Cai; H. Caines; M. Calderón de La Barca Sánchez; O. Catu; D. Cebra; R. Cendejas; M. C. Cervantes; Z. Chajecki; P. Chaloupka; S. Chattopadhyay; H. F. Chen; J. H. Chen; J. Cheng; M. Cherney; A. Chikanian; K. E. Choi; W. Christie; P. Chung; R. F. Clarke; M. J. M. Codrington; R. Corliss; T. M. Cormier; M. R. Cosentino; J. G. Cramer; H. J. Crawford; D. Das; S. Dash; M. Daugherity; L. C. de Silva; T. G. Dedovich; M. Dephillips; A. A. Derevschikov; R. Derradi de Souza; L. Didenko; P. Djawotho; V. Dzhordzhadze; S. M. Dogra; X. Dong; J. L. Drachenberg; J. E. Draper; J. C. Dunlop; M. R. Dutta Mazumdar; L. G. Efimov; E. Elhalhuli; M. Elnimr; J. Engelage; G. Eppley; B. Erazmus; M. Estienne; L. Eun; P. Fachini; R. Fatemi; J. Fedorisin; A. Feng; P. Filip; E. Finch; V. Fine; Y. Fisyak; C. A. Gagliardi; D. R. Gangadharan; M. S. Ganti; E. J. Garcia-Solis; A. Geromitsos; F. Geurts; V. Ghazikhanian; P. Ghosh; Y. N. Gorbunov; A. Gordon; O. Grebenyuk; D. Grosnick; B. Grube; S. M. Guertin; K. S. F. F. Guimaraes; A. Gupta; N. Gupta; W. Guryn; B. Haag; T. J. Hallman; A. Hamed; J. W. Harris; M. Heinz; S. Heppelmann; A. Hirsch; E. Hjort; A. M. Hoffman; G. W. Hoffmann; D. J. Hofman; R. S. Hollis; H. Z. Huang; T. J. Humanic; L. Huo; G. Igo; A. Iordanova; P. Jacobs; W. W. Jacobs; P. Jakl; C. Jena; F. Jin; C. L. Jones; P. G. Jones; J. Joseph; E. G. Judd; S. Kabana; K. Kajimoto; K. Kang; J. Kapitan; K. Kauder; D. Keane; A. Kechechyan; D. Kettler; V. Yu. Khodyrev; D. P. Kikola; J. Kiryluk; A. Kisiel; S. R. Klein; A. G. Knospe; A. Kocoloski; D. D. Koetke; J. Konzer; M. Kopytine; I. Koralt; W. Korsch; L. Kotchenda; V. Kouchpil; P. Kravtsov; V. I. Kravtsov; K. Krueger; M. Krus; L. Kumar; P. Kurnadi; M. A. C. Lamont; J. M. Landgraf; S. Lapointe; J. Lauret; A. Lebedev; R. Lednicky; C.-H. Lee; J. H. Lee; W. Leight; M. J. Levine; C. Li; N. Li; Y. Li; G. Lin; S. J. Lindenbaum; M. A. Lisa; F. Liu; H. Liu; J. Liu; L. Liu; T. Ljubicic; W. J. Llope; R. S. Longacre; W. A. Love; Y. Lu; T. Ludlam; G. L. Ma; Y. G. Ma; D. P. Mahapatra; R. Majka; O. I. Mall; L. K. Mangotra; R. Manweiler; S. Margetis; C. Markert; H. Masui; H. S. Matis; Yu. A. Matulenko; D. McDonald; T. S. McShane; A. Meschanin; R. Milner; N. G. Minaev; S. Mioduszewski; A. Mischke; B. Mohanty; D. A. Morozov; M. G. Munhoz; B. K. Nandi; C. Nattrass; T. K. Nayak; J. M. Nelson; P. K. Netrakanti; M. J. Ng; L. V. Nogach; S. B. Nurushev; G. Odyniec; A. Ogawa; H. Okada; V. Okorokov; D. Olson; M. Pachr; B. S. Page; S. K. Pal; Y. Pandit; Y. Panebratsev; T. Pawlak; T. Peitzmann; V. Perevoztchikov; C. Perkins; W. Peryt; S. C. Phatak; P. Pile; M. Planinic; M. A. Ploskon; J. Pluta; D. Plyku; N. Poljak; A. M. Poskanzer; B. V. K. S. Potukuchi; D. Prindle; C. Pruneau; N. K. Pruthi; P. R. Pujahari; J. Putschke; R. Raniwala; S. Raniwala; R. L. Ray; R. Redwine; R. Reed; A. Ridiger; H. G. Ritter; J. B. Roberts; O. V. Rogachevskiy; J. L. Romero; A. Rose; C. Roy; L. Ruan; M. J. Russcher; R. Sahoo; S. Sakai; I. Sakrejda; T. Sakuma; S. Salur; J. Sandweiss; J. Schambach; R. P. Scharenberg; N. Schmitz; J. Seele; J. Seger; I. Selyuzhenkov; Y. Semertzidis; P. Seyboth; E. Shahaliev; M. Shao; M. Sharma; S. S. Shi; X.-H. Shi; E. P. Sichtermann; F. Simon; R. N. Singaraju; M. J. Skoby; N. Smirnov; P. Sorensen; J. Sowinski; H. M. Spinka; B. Srivastava; T. D. S. Stanislaus; D. Staszak; M. Strikhanov; B. Stringfellow; A. A. P. Suaide; M. C. Suarez; N. L. Subba; M. Sumbera; X. M. Sun; Y. Sun; Z. Sun; B. Surrow; T. J. M. Symons; A. Szanto de Toledo; J. Takahashi; A. H. Tang; Z. Tang; L. H. Tarini; T. Tarnowsky; D. Thein; J. H. Thomas; J. Tian; A. R. Timmins; S. Timoshenko; D. Tlusty; M. Tokarev; V. N. Tram; S. Trentalange; R. E. Tribble; O. D. Tsai; J. Ulery; T. Ullrich; D. G. Underwood; G. van Buren; G. van Nieuwenhuizen; J. A. Vanfossen Jr.; R. Varma; G. M. S. Vasconcelos; A. N. Vasiliev; F. Videbaek; Y. P. Viyogi; S. Vokal; M. Wada; M. Walker; F. Wang; G. Wang; H. Wang; J. S. Wang; Q. Wang; X. Wang; Y. Wang; G. Webb; J. C. Webb; G. D. Westfall; C. Whitten Jr.; H. Wieman; S. W. Wissink; R. Witt; Y. Wu; W. Xie; N. Xu; Q. H. Xu; Y. Xu; Z. Xu; Y. Yang; P. Yepes; K. Yip; I.-K. Yoo; Q. Yue; M. Zawisza; H. Zbroszczyk; W. Zhan; S. Zhang; W. M. Zhang; X. P. Zhang; Y. Zhang; Z. P. Zhang; Y. Zhao; C. Zhong; J. Zhou; X. Zhu; R. Zoulkarneev; Y. Zoulkarneeva; J. X. Zuo

    2010-01-01

    Parity (P)-odd domains, corresponding to nontrivial topological solutions of the QCD vacuum, might be created during relativistic heavy-ion collisions. These domains are predicted to lead to charge separation of quarks along the orbital momentum of the system created in noncentral collisions. To study this effect, we investigate a three-particle mixed-harmonics azimuthal correlator which is a P-even observable, but directly sensitive

  14. BIOPHYSICS LETTER Transport at the nanoscale: temperature dependence

    E-print Network

    Movileanu, Liviu

    BIOPHYSICS LETTER Transport at the nanoscale: temperature dependence of ion conductance Catalin European Biophysical Societies' Association 2008 Abstract Temperature dependent ion conductance details of the ion transport. Comparing the temperature dependence of the channel conductance

  15. Time-dependent modelling of mass-loading, transport, chemistry and magnetic fields in Jupiter's magnetosphere

    NASA Astrophysics Data System (ADS)

    Arridge, C. S.

    2013-12-01

    Radial profiles of plasma flux tube content are often modelled using diffusive plasma transport using an assumed source rate and diffusion coefficient. Such diffusive transport modelling can be combined with neutral-cloud theory to provide time-dependent chemistry in the plasma torus. Independently, and not necessarily self-consistently, the radial profile of the plasma azimuthal velocity can be calculated using the Hill-Pontius equation, for the mathematically separable case where the source and transport regions are spatially distinct. These steady state profiles can be imposed into a magnetospheric model to understand the resulting fields and currents. In a non-steady state where the plasma source rate is varying, and/or the outflowing plasma is not in equilibrium, these solutions do not apply. Hence, important questions concerning time-dependent variability in the jovian and saturnian magnetospheres cannot be adequately addressed using such models. In this paper we present a new approach where we solve the time-dependent equations for diffusive radial transport of both mass and angular momentum coupled with a neutral-plasma chemistry model, thus allowing for time-dependent plasma sources and the motion of radial structures produced by such time-dependence. These time-dependent solutions are coupled to an Euler potential magnetospheric model to calculate time-dependent magnetospheric configurations. We present our modelling methodology and the first results from this coupled model.

  16. Temperature-Dependent Transport in Suspended Graphene

    Microsoft Academic Search

    K. I. Bolotin; K. J. Sikes; J. Hone; H. L. Stormer; P. Kim

    2008-01-01

    The resistivity of ultraclean suspended graphene is strongly temperature (T) dependent for 5transport is near-ballistic in a device of ˜2mum dimension and a mobility ˜170000cm2\\/Vs. At large carrier density, n>0.5×1011cm-2, the resistivity increases with increasing T and is linear above 50 K, suggesting carrier scattering from acoustic phonons. At T=240K the mobility is ˜120000cm2\\/Vs, higher than

  17. Temperature-dependent Transport Properties of Graphene

    NASA Astrophysics Data System (ADS)

    Zhong, Bochen; Singh, Amol; Uddin, Ahsan; Koley, Goutam; Webb, Richard

    2014-03-01

    Temperature-dependent transport properties of graphene synthesized by chemical vapor deposition (CVD) on a Cu thin sheet have been investigated. Raman spectra of our samples show good quality of the CVD graphene. We have measured the temperature dependence of conductivity, charge-carrier density and Hall mobility of graphene by patterning them into micrometer-sized Hall bars. Quantum Hall effect has been observed when the temperature is about 60 Kelvin, which is the evidence for single-layer graphene. Furthermore, the results of temperature dependence of Hall mobility indicate that impurity and defect scattering is the primary scattering mechanism at low temperature, while substrate surface polar phonon scattering is dominant at high temperature.

  18. Transverse-rapidity yt dependence of the nonjet azimuth quadrupole from 62- and 200-GeV Au-Au collisions

    NASA Astrophysics Data System (ADS)

    Kettler, David T.; Prindle, Duncan J.; Trainor, Thomas A.

    2015-06-01

    Previous measurements of a quadrupole component of azimuth correlations denoted by symbol v2 have been interpreted to represent elliptic flow, a hydrodynamic phenomenon conjectured to play a major role in noncentral nucleus-nucleus collisions. v2 measurements provide the main support for conclusions that a "perfect liquid" is formed in heavy-ion collisions at the Relativistic Heavy Ion Collider. However, conventional v2 methods based on one-dimensional (1D) azimuth correlations give inconsistent results and may include a jet contribution. In some cases the data trends appear to be inconsistent with hydrodynamic interpretations. In this study we distinguish several components of 2D angular correlations and isolate a nonjet (NJ) azimuth quadrupole denoted by v2{2D} . We establish systematic variations of the NJ quadrupole on yt, centrality, and collision energy. We adopt transverse-rapidity yt as both a velocity measure and a logarithmic alternative to transverse momentum pt. Based on NJ-quadrupole trends, we derive a completely factorized universal parametrization of quantity v2{2D} (yt,b ,?{sN N}) which describes the centrality, yt, and energy dependence. From yt-differential v2(yt) data we isolate a quadrupole spectrum and infer a quadrupole source boost having unexpected properties. NJ quadrupole v2 trends obtained with 2D model fits are remarkably simple. The centrality trend appears to be uncorrelated with a sharp transition in jet-related structure that may indicate rapid change of Au-Au medium properties. The lack of correspondence suggests that the NJ quadrupole may be insensitive to such a medium. Several quadrupole trends have interesting implications for hydro interpretations.

  19. Particle-type dependence of azimuthal anisotropy and nuclearmodification of particle production in Au+Au collisions at sNN = 200GeV

    SciTech Connect

    Adams, J.; Adler, C.; Aggarwal, M.M.; Ahammed, Z.; Amonett, J.; Anderson, B.D.; Anderson, M.; Arkhipkin, D.; Averichev, G.S.; Badyal,S.K.; Balewski, J.; Barannikova, O.; Barnby, L.S.; Baudot, J.; Bekele,S.; Belaga, V.V.; Bellwied, R.; Berger, J.; Bezverkhny, B.I.; Bhardwaj,S.; Bhaskar, P.; Bhati, A.K.; Billmeier, A.; Bland, L.C.; Blyth, C.O.; Bonner, B.E.; Botje, M.; Boucham, A.; Brandin, A.; Bravar, A.; Cadman,R.V.; Cai, X.Z.; Caines, H.; Calderon de la Barca Sanchez, M.; Carroll,J.; Castillo, J.; Castro, M.; Cebra, D.; Chaloupka, P.; Chattopadhyay,S.; Chen, H.F.; Chen, Y.; Chernenko, S.P.; Cherney, M.; Chikanian, A.; Choi, B.; Christie, W.; Coffin, J.P.; Cormier, T.M.; Cramer, J.G.; Crawford, H.J.; Das, D.; Das, S.; Derevschikov, A.A.; Didenko, L.; Dietel, T.; Dong, W.J.; Dong, X.; Draper, J.E.; Du, F.; Dubey, A.K.; Dunin, V.B.; Dunlop, J.C.; Dutta Majumdar, M.R.; Eckardt, V.; Efimov,L.G.; Emelianov, V.; Engelage, J.; Eppley, G.; Erazmus, B.; Fachini, P.; Faine, V.; Faivre, J.; Fatemi, R.; Filimonov, K.; Filip, P.; Finch, E.; Fisyak, Y.; Flierl, D.; Foley, K.J.; Fu, J.; Gagliardi, C.A.; Gagunashvili, N.; Gans, J.; Ganti, M.S.; Gutierrez, T.D.; Gaudichet, L.; Germain, M.; Geurts, F.; Ghazikhanian, V.; Ghosh, P.; Gonzalez, J.E.; Grachov, O.; Grigoriev, V.; Gronstal, S.; Drosnick, D.; Guedon, M.; Guertin, S.M.; Gushin, E.; Hallman, T.J.; Hardtke, D.; Harris, J.W.; Heinz, M.; Henry, T.W.; Heppelmann, S.; Herston, T.; Hippolyte, B.; Hirsch, A.; Hjort, E.; Hoffmann, G.W.; Horsley, M.; Huang, H.Z.; Huang,S.L.; Humanic, T.J.; Igo, G.; Ishihara, A.; Jacobs, P.; Jacobs, W.W.; Janik, M.; Johnson, I.; Jones, P.G.; Judd, E.G.; Kabana, S.; Kaneta, M.; Kaplan, M.; Keane, D.; Kiryluk, J.; Kisiel, A.; Klay, J.; Klein, S.R.; Klyachko, A.; Koetke, D.D.; Kollegger, T.; Konstantinov, A.; Kopytine,S.M.; Kotchenda, L.; Kovalenko, A.D.; Kramer, M.; Kravtsov, P.; Krueger,K.; Kuhn, C.; Kulikov, A.I.; Kunde, G.J.; Kunz, C.L.; Kutuev, R.K.; et al.

    2003-06-18

    We present STAR measurements of the azimuthal anisotropy parameter v{sub 2} and the binary-collision scaled centrality ratio R{sub CP} for kaons and lambdas ({Lambda} + {bar {Lambda}}) at mid-rapidity in Au+Au collisions at {radical}s{sub NN} = 200 GeV. In combination, the v{sub 2} and R{sub CP} particle-type dependencies contradict expectations from partonic energy loss followed by standard fragmentation in vacuum. We establish p{sub T} {approx} 5 GeV/c as the value where the centrality dependent baryon enhancement ends. The K{sub S}{sup 0} and {Lambda} + {bar {Lambda}} v{sub 2} values are consistent with expectations of constituent-quark-number scaling from models of hadron formation by parton coalescence or recombination.

  20. Observation of charge-dependent azimuthal correlations and possible local strong parity violation in heavy-ion collisions

    SciTech Connect

    STAR Collaboration; Abelev, Betty

    2010-07-05

    Parity-odd domains, corresponding to non-trivial topological solutions of the QCD vacuum, might be created during relativistic heavy-ion collisions. These domains are predicted to lead to charge separation of quarks along the orbital momentum of the system created in non-central collisions. To study this effect, we investigate a three particle mixed harmonics azimuthal correlator which is a {Rho}-even observable, but directly sensitive to the charge separation effect. We report measurements of this observable using the STAR detector in Au+Au and Cu+Cu collisions at {radical}s{sub NN} = 200 and 62 GeV. The results are presented as a function of collision centrality, particle separation in rapidity, and particle transverse momentum. A signal consistent with several of the theoretical expectations is detected in all four data sets. We compare our results to the predictions of existing event generators, and discuss in detail possible contributions from other effects that are not related to parity violation.

  1. Observation of charge-dependent azimuthal correlations and possible local strong parity violation in heavy-ion collisions

    NASA Astrophysics Data System (ADS)

    Abelev, B. I.; Aggarwal, M. M.; Ahammed, Z.; Alakhverdyants, A. V.; Anderson, B. D.; Arkhipkin, D.; Averichev, G. S.; Balewski, J.; Barannikova, O.; Barnby, L. S.; Baumgart, S.; Beavis, D. R.; Bellwied, R.; Benedosso, F.; Betancourt, M. J.; Betts, R. R.; Bhasin, A.; Bhati, A. K.; Bichsel, H.; Bielcik, J.; Bielcikova, J.; Biritz, B.; Bland, L. C.; Bnzarov, I.; Bonner, B. E.; Bouchet, J.; Braidot, E.; Brandin, A. V.; Bridgeman, A.; Bruna, E.; Bueltmann, S.; Burton, T. P.; Cai, X. Z.; Caines, H.; Calderón de La Barca Sánchez, M.; Catu, O.; Cebra, D.; Cendejas, R.; Cervantes, M. C.; Chajecki, Z.; Chaloupka, P.; Chattopadhyay, S.; Chen, H. F.; Chen, J. H.; Chen, J. Y.; Cheng, J.; Cherney, M.; Chikanian, A.; Choi, K. E.; Christie, W.; Chung, P.; Clarke, R. F.; Codrington, M. J. M.; Corliss, R.; Cormier, T. M.; Cosentino, M. R.; Cramer, J. G.; Crawford, H. J.; Das, D.; Dash, S.; Daugherity, M.; de Silva, L. C.; Dedovich, T. G.; Dephillips, M.; Derevschikov, A. A.; Derradi de Souza, R.; Didenko, L.; Djawotho, P.; Dzhordzhadze, V.; Dogra, S. M.; Dong, X.; Drachenberg, J. L.; Draper, J. E.; Dunlop, J. C.; Dutta Mazumdar, M. R.; Efimov, L. G.; Elhalhuli, E.; Elnimr, M.; Engelage, J.; Eppley, G.; Erazmus, B.; Estienne, M.; Eun, L.; Fachini, P.; Fatemi, R.; Fedorisin, J.; Feng, A.; Filip, P.; Finch, E.; Fine, V.; Fisyak, Y.; Gagliardi, C. A.; Gangadharan, D. R.; Ganti, M. S.; Garcia-Solis, E. J.; Geromitsos, A.; Geurts, F.; Ghazikhanian, V.; Ghosh, P.; Gorbunov, Y. N.; Gordon, A.; Grebenyuk, O.; Grosnick, D.; Grube, B.; Guertin, S. M.; Guimaraes, K. S. F. F.; Gupta, A.; Gupta, N.; Guryn, W.; Haag, B.; Hallman, T. J.; Hamed, A.; Harris, J. W.; Heinz, M.; Heppelmann, S.; Hirsch, A.; Hjort, E.; Hoffman, A. M.; Hoffmann, G. W.; Hofman, D. J.; Hollis, R. S.; Huang, H. Z.; Humanic, T. J.; Huo, L.; Igo, G.; Iordanova, A.; Jacobs, P.; Jacobs, W. W.; Jakl, P.; Jena, C.; Jin, F.; Jones, C. L.; Jones, P. G.; Joseph, J.; Judd, E. G.; Kabana, S.; Kajimoto, K.; Kang, K.; Kapitan, J.; Kauder, K.; Keane, D.; Kechechyan, A.; Kettler, D.; Khodyrev, V. Yu.; Kikola, D. P.; Kiryluk, J.; Kisiel, A.; Klein, S. R.; Knospe, A. G.; Kocoloski, A.; Koetke, D. D.; Konzer, J.; Kopytine, M.; Koralt, I.; Korsch, W.; Kotchenda, L.; Kouchpil, V.; Kravtsov, P.; Kravtsov, V. I.; Krueger, K.; Krus, M.; Kumar, L.; Kurnadi, P.; Lamont, M. A. C.; Landgraf, J. M.; Lapointe, S.; Lauret, J.; Lebedev, A.; Lednicky, R.; Lee, C.-H.; Lee, J. H.; Leight, W.; Levine, M. J.; Li, C.; Li, N.; Li, Y.; Lin, G.; Lindenbaum, S. J.; Lisa, M. A.; Liu, F.; Liu, H.; Liu, J.; Liu, L.; Ljubicic, T.; Llope, W. J.; Longacre, R. S.; Love, W. A.; Lu, Y.; Ludlam, T.; Ma, G. L.; Ma, Y. G.; Mahapatra, D. P.; Majka, R.; Mall, O. I.; Mangotra, L. K.; Manweiler, R.; Margetis, S.; Markert, C.; Masui, H.; Matis, H. S.; Matulenko, Yu. A.; McDonald, D.; McShane, T. S.; Meschanin, A.; Milner, R.; Minaev, N. G.; Mioduszewski, S.; Mischke, A.; Mohanty, B.; Morozov, D. A.; Munhoz, M. G.; Nandi, B. K.; Nattrass, C.; Nayak, T. K.; Nelson, J. M.; Netrakanti, P. K.; Ng, M. J.; Nogach, L. V.; Nurushev, S. B.; Odyniec, G.; Ogawa, A.; Okada, H.; Okorokov, V.; Olson, D.; Pachr, M.; Page, B. S.; Pal, S. K.; Pandit, Y.; Panebratsev, Y.; Pawlak, T.; Peitzmann, T.; Perevoztchikov, V.; Perkins, C.; Peryt, W.; Phatak, S. C.; Pile, P.; Planinic, M.; Ploskon, M. A.; Pluta, J.; Plyku, D.; Poljak, N.; Poskanzer, A. M.; Potukuchi, B. V. K. S.; Prindle, D.; Pruneau, C.; Pruthi, N. K.; Pujahari, P. R.; Putschke, J.; Raniwala, R.; Raniwala, S.; Ray, R. L.; Redwine, R.; Reed, R.; Ridiger, A.; Ritter, H. G.; Roberts, J. B.; Rogachevskiy, O. V.; Romero, J. L.; Rose, A.; Roy, C.; Ruan, L.; Russcher, M. J.; Sahoo, R.; Sakai, S.; Sakrejda, I.; Sakuma, T.; Salur, S.; Sandweiss, J.; Schambach, J.; Scharenberg, R. P.; Schmitz, N.; Seele, J.; Seger, J.; Selyuzhenkov, I.; Semertzidis, Y.; Seyboth, P.; Shahaliev, E.; Shao, M.; Sharma, M.; Shi, S. S.; Shi, X.-H.; Sichtermann, E. P.; Simon, F.; Singaraju, R. N.; Skoby, M. J.; Smirnov, N.; Sorensen, P.; Sowinski, J.; Spinka, H. M.; Srivastava, B.; Stanislaus, T. D. S.; Staszak, D.; Strikhanov, M.; Stringfellow, B.; Suaide, A. A. P.; Suarez, M. C.; Subba, N. L.; Sumbera, M.; Sun, X. M.; Sun, Y.; Sun, Z.; Surrow, B.; Symons, T. J. M.; Szanto de Toledo, A.; Takahashi, J.; Tang, A. H.; Tang, Z.; Tarini, L. H.; Tarnowsky, T.; Thein, D.; Thomas, J. H.; Tian, J.; Timmins, A. R.; Timoshenko, S.; Tlusty, D.; Tokarev, M.; Tram, V. N.; Trentalange, S.; Tribble, R. E.; Tsai, O. D.; Ulery, J.; Ullrich, T.; Underwood, D. G.; van Buren, G.; van Nieuwenhuizen, G.; Vanfossen, J. A., Jr.; Varma, R.; Vasconcelos, G. M. S.; Vasiliev, A. N.; Videbaek, F.; Viyogi, Y. P.; Vokal, S.; Voloshin, S. A.; Wada, M.; Walker, M.; Wang, F.; Wang, G.; Wang, H.; Wang, J. S.; Wang, Q.; Wang, X.

    2010-05-01

    Parity (P)-odd domains, corresponding to nontrivial topological solutions of the QCD vacuum, might be created during relativistic heavy-ion collisions. These domains are predicted to lead to charge separation of quarks along the orbital momentum of the system created in noncentral collisions. To study this effect, we investigate a three-particle mixed-harmonics azimuthal correlator which is a P-even observable, but directly sensitive to the charge-separation effect. We report measurements of this observable using the STAR detector in Au+Au and Cu+Cu collisions at sNN=200 and 62 GeV. The results are presented as a function of collision centrality, particle separation in rapidity, and particle transverse momentum. A signal consistent with several of the theoretical expectations is detected in all four data sets. We compare our results to the predictions of existing event generators and discuss in detail possible contributions from other effects that are not related to P violation.

  2. Spin Dependent Transport in Novel Magnetic Heterostructures

    NASA Astrophysics Data System (ADS)

    Jayathilaka, Priyanga Buddhika

    Magnetic oxides have become of interest source for spin transport devices due to their high spin polarization. But the real applications of these oxides remains unsatisfactory up to date, mostly due to the change of properties as a result of nano structuring. Magnetite (Fe3O4) is one such a material. High Curie temperature and the half metallicity of Fe 3O4 make it a good potential candidate for spin transport devices. Studies have shown that the nano structuring Fe3O 4 changes most of it's important properties. This includes high saturation magnetization and drop of conductivity by a few orders of magnitude in Fe 3O4 thin films. In this study, we have successfully grown Fe3O4 by reactive sputtering and studied the effect of transition metal buffer layers on structural, transport, and magnetic properties of Fe3O 4. It is shown that the lattice strain created by different buffer layers has major impacts on the properties of Fe3O4 thin films. Also for the first time, the magnetic force microscopic measurements were carried out in Fe3O4 thin films through Verway transition. MFM data with the magnetization data have confirmed that the magnetization of Fe3O4 thin films rotate slightly out of the plane below the Verway transition. Fe3O4 thin films were also successfully used in fabricating spin valve structures with Chromium and Permalloy. Here, the Fe 3O4 was used to generated the spin polarized electrons through reflection instead of direct spin injection. This is a novel method that can be used to inject spins into materials with different conductivities, where the traditional direct spin injection fails. Also the effect of growth field on Fe3O4 and Fe3O4/Cr/Py spin valves were investigated. In Fe3O4 the growth field induced an uni-axial anisotropy while it creates a well define parallel and anti-parallel states in spin valves. Magneto thermal phenomenon including spin dependent Seebeck effectt, Planar Nernst effectt and Anomalous Nernst effectt were measured in ferromagnetic thin films and spin valves. Spin dependent Seebeck effectt and planar Nernst effectt were directly compared with the charge counterpart anisotropic magneto resistance. All the effects exhibited similar behavior indicating the same origin, namely spin dependent scattering.

  3. Stacking dependent electronic structure and transport in bilayer graphene nanoribbons

    E-print Network

    Pandey, Ravi

    Stacking dependent electronic structure and transport in bilayer graphene nanoribbons Xiaoliang University, Houghton, MI 49931, USA b US Army Research Laboratory, Weapons and Materials Research Directorate T The stacking-dependent electronic structure and transport properties of bilayer graphene nanoribbons suspended

  4. Rapidity, azimuthal, and multiplicity dependence of mean transverse momentum and transverse momentum correlations in {pi}{sup +}p and K{sup +}p collisions in {radical}(s)=22 GeV

    SciTech Connect

    Atayan, M.R.; Gulkanyan, H. [Institute of Physics, AM-375036 Yerevan (Armenia); Bai Yuting [Institute of Particle Physics, Hua-Zhong Normal University, Wuhan 430079 (China); De Wolf, E.A. [Department of Physics, University of Antwerp, B-2610 Wilrijk (Belgium); Endler, A.M.F. [Centro Brasileiro de Pesquisas Fisicas, BR-22290 Rio de Janeiro (Brazil); Fu Jinghua; Huang Yanping; Liu Lianshou; Wu Yuanfang [Institute of Particle Physics, Hua-Zhong Normal University, Wuhan 430079 (China); Hakobyan, R. [Institute of Physics, AM-375036 Yerevan (Armenia); Kittel, W. [Radboud University/NIKHEF, NL-6525 ED Nijmegen (Netherlands); Li Zhiming [Institute of Particle Physics, Hua-Zhong Normal University, Wuhan 430079 (China); Radboud University/NIKHEF, NL-6525 ED Nijmegen (Netherlands); Metreveli, Z.V.; Tomaradze, A.G. [Institute for High Energy Physics of Tbilisi State University, GE-380086 Tbilisi (Georgia) and Northwestern University, Evanston, Illinois (United States); Smirnova, L.N.; Tikhonova, L.A. [Scobeltsyn Institute of Nuclear Physics, Lomonosow Moscow State University, RU-119899 Moscow (Russian Federation); Zotkin, S.A. [Scobeltsyn Institute of Nuclear Physics, Lomonosow Moscow State University, RU-119899 Moscow (Russian Federation); DESY, Hamburg (Germany)

    2006-04-01

    Rapidity, azimuthal and multiplicity dependence of mean transverse momentum and transverse momentum correlations of charged particles is studied in {pi}{sup +}p and K{sup +}p collisions at 250 GeV/c incident beam momentum. For the first time, it is found that the rapidity dependence of the two-particle transverse momentum correlation is different from that of the mean transverse momentum, but both have similar multiplicity dependence. In particular, the transverse momentum correlations are boost invariant. This is similar to the recently found boost invariance of the charge balance function. A strong azimuthal dependence of the transverse momentum correlations originates from the constraint of energy-momentum conservation. The results are compared with those from the PYTHIA Monte Carlo generator. The similarities to and differences with the results from current heavy ion experiments are discussed.

  5. Sodium-dependent carnitine transport in human placental choriocarcinoma cells.

    PubMed

    Prasad, P D; Huang, W; Ramamoorthy, S; Carter, A L; Leibach, F H; Ganapathy, V

    1996-10-01

    The JAR human placental choriocarcinoma cells were found to transport carnitine into the intracellular space by a Na(+)-dependent process. The transport showed no requirement for anions. The Na+-dependent process was saturable and the apparent Michaelis-Menten constant for carnitine was 12.3 +/- 0.5 microM. Na+ activated the transport by increasing the affinity of the transport system for carnitine. The transport system specifically interacted with L-carnitine, D-carnitine, acetyl-DL-carnitine and betaine. 6-N-Trimethyllysine and choline had little or no effect on carnitine transport. Of the total transport measured, transport into the intracellular space represented 90%. Plasma membrane vesicles prepared from JAR cells were found to bind carnitine in a Na(+)-dependent manner. The binding was saturable with an apparent dissociation constant of 0.66 +/- 0.08 microM. The binding process was specific for L-carnitine, D-carnitine, acetyl-DL-carnitine, and betaine. 6-N-Trimethyllysine and choline showed little or no affinity. It is concluded that the JAR cells express a Na(+)-dependent high-affinity system for carnitine transport and that the Na(+)-dependent high-affinity carnitine binding detected in purified JAR cell plasma membrane vesicles is possibly related to the transmembrane transport process. PMID:8865821

  6. Azimuthal anisotropy of the Pacific region

    NASA Astrophysics Data System (ADS)

    Maggi, Alessia; Debayle, Eric; Priestley, Keith; Barruol, Guilhem

    2006-10-01

    Azimuthal anisotropy is the dependence of local seismic properties on the azimuth of propagation. We present the azimuthally anisotropic component of a 3D SV velocity model for the Pacific Ocean, derived from the waveform modeling of over 56,000 multi-mode Rayleigh waves followed by a simultaneous inversion for isotropic and azimuthally anisotropic vsv structure. The isotropic vsv model is discussed in a previous paper (A. Maggi, E. Debayle, K. Priestley, G. Barruol, Multi-mode surface waveform tomography of the Pacific Ocean: a close look at the lithospheric cooling signature, Geophys. J. Int. 166 (3) (2006). doi:10.1111/j.1365-246x.2006.03037.x). The azimuthal anisotropy we find is consistent with the lattice preferred orientation model (LPO): the hypothesis of anisotropy generation in the Earth's mantle by preferential alignment of anisotropic crystals in response to the shear strains induced by mantle flow. At lithospheric depths we find good agreement between fast azimuthal anisotropy orientations and ridge spreading directions recorded by sea-floor magnetic anomalies. At asthenospheric depths we find a strong correlation between fast azimuthal anisotropy orientations and the directions of current plate motions. We observe perturbations in the pattern of seismic anisotropy close to Pacific hot-spots that are consistent with the predictions of numerical models of LPO generation in plume-disturbed plate motion-driven mantle flow. These observations suggest that perturbations in the patterns of azimuthal anisotropy may provide indirect evidence for plume-like upwelling in the mantle.

  7. Temperature Dependence of Vertical Transport in Quantum Hall Multilayers

    NASA Astrophysics Data System (ADS)

    Walling, H. A.; Dougherty, D. P.; Druist, D. P.; Gwinn, E. G.; Maranowski, K. D.; Gossard, A. C.

    2001-03-01

    We study the temperature dependence of vertical transport in AlGaAs/GaAs multilayers in the regime of the quantum Hall effect. At low temperatures vertical transport in quantum Hall states occurs on a 2D chiral sheath of edge states near the sidewalls of the sample mesas. At higher temperatures variable range hopping through the bulk of the sample dominates. To extend the temperature range of sheath-dominated transport, we increase the device perimeters using fractal-shaped mesas defined by e-beam lithography. We report on the freeze-out of bulk transport and the weak temperature dependence of the sheath conductivity.

  8. Transverse-rapidity $\\bf y_t$ dependence of the nonjet azimuth quadrupole from 62 and 200 GeV Au-Au collisions

    E-print Network

    Kettler, David T; Trainor, Thomas A

    2015-01-01

    Previous measurements of a quadrupole component of azimuth correlations denoted by symbol $v_2$ have been interpreted to represent elliptic flow, a hydrodynamic phenomenon conjectured to play a major role in noncentral nucleus-nucleus collisions. $v_2$ measurements provide the main support for conclusions that a ``perfect liquid'' is formed in heavy ion collisions at the Relativistic Heavy Ion Collider (RHIC). However, conventional $v_2$ methods based on one-dimensional (1D) azimuth correlations give inconsistent results and may include a jet contribution. In some cases the data trends appear to be inconsistent with hydrodynamic interpretations. In this study we distinguish several components of 2D angular correlations and isolate a nonjet (NJ) azimuth quadrupole denoted by $v_2\\{\\text{2D}\\}$. We establish systematic variations of the NJ quadrupole on $y_t$, centrality and collision energy. We adopt transverse rapidity $y_t$ as both a velocity measure and as a logarithmic alternative to transverse momentum $p...

  9. Time-dependent density functional theory for quantum transport

    NASA Astrophysics Data System (ADS)

    Kwok, Yanho; Zhang, Yu; Chen, GuanHua

    2014-12-01

    The rapid miniaturization of electronic devices motivates research interests in quantum transport. Recently time-dependent quantum transport has become an important research topic. Here we review recent progresses in the development of time-dependent density-functional theory for quantum transport including the theoretical foundation and numerical algorithms. In particular, the reduced-single electron density matrix based hierarchical equation of motion, which can be derived from Liouville-von Neumann equation, is reviewed in details. The numerical implementation is discussed and simulation results of realistic devices will be given.

  10. Electrogenic nature of rat sodium-dependent multivitamin transport.

    PubMed

    Prasad, P D; Srinivas, S R; Wang, H; Leibach, F H; Devoe, L D; Ganapathy, V

    2000-04-21

    We report on the electrogenic nature of the transport process mediated by the rat sodium-dependent multivitamin transporter. In Cos-7 cells, the relationship of Na(+) concentration versus biotin and pantothenate uptake rate was sigmoidal with a Na(+):substrate stoichiometry of 2:1. In Cos-7 cells expressing rat SMVT biotin transport was significantly higher when the membrane was hyperpolarized and considerably reduced when the membrane was depolarized. Similarly, biotin uptake in X. laevis oocytes expressing rat SMVT was inhibited with depolarized oocyte membrane by altering the K(+) permeability across the membrane. It is concluded that the transport of biotin and pantothenate mediated by rat SMVT is electrogenic with a Na(+):substrate coupling ratio of 2:1 and that the transport process is associated with the transfer of one net positive charge across the membrane per transport cycle. PMID:10772912

  11. TonB-dependent transporters and their occurrence in cyanobacteria

    PubMed Central

    Mirus, Oliver; Strauss, Sascha; Nicolaisen, Kerstin; von Haeseler, Arndt; Schleiff, Enrico

    2009-01-01

    Background Different iron transport systems evolved in Gram-negative bacteria during evolution. Most of the transport systems depend on outer membrane localized TonB-dependent transporters (TBDTs), a periplasma-facing TonB protein and a plasma membrane localized machinery (ExbBD). So far, iron chelators (siderophores), oligosaccharides and polypeptides have been identified as substrates of TBDTs. For iron transport, three uptake systems are defined: the lactoferrin/transferrin binding proteins, the porphyrin-dependent transporters and the siderophore-dependent transporters. However, for cyanobacteria almost nothing is known about possible TonB-dependent uptake systems for iron or other substrates. Results We have screened all publicly available eubacterial genomes for sequences representing (putative) TBDTs. Based on sequence similarity, we identified 195 clusters, where elements of one cluster may possibly recognize similar substrates. For Anabaena sp. PCC 7120 we identified 22 genes as putative TBDTs covering almost all known TBDT subclasses. This is a high number of TBDTs compared to other cyanobacteria. The expression of the 22 putative TBDTs individually depends on the presence of iron, copper or nitrogen. Conclusion We exemplified on TBDTs the power of CLANS-based classification, which demonstrates its importance for future application in systems biology. In addition, the tentative substrate assignment based on characterized proteins will stimulate the research of TBDTs in different species. For cyanobacteria, the atypical dependence of TBDT gene expression on different nutrition points to a yet unknown regulatory mechanism. In addition, we were able to clarify a hypothesis of the absence of TonB in cyanobacteria by the identification of according sequences. PMID:19821963

  12. Centrality dependence of dihadron correlations and azimuthal anisotropy harmonics in PbPb collisions at $\\sqrt{s_{NN}}=2.76$ TeV

    SciTech Connect

    Chatrchyan, Serguei; et al.

    2012-05-01

    Measurements from the CMS experiment at the LHC of dihadron correlations for charged particles produced in PbPb collisions at a nucleon-nucleon centre-of-mass energy of 2.76 TeV are presented. The results are reported as a function of the particle transverse momenta (pt) and collision centrality over a broad range in relative pseudorapidity [Delta(eta)] and the full range of relative azimuthal angle [Delta(phi)]. The observed two-dimensional correlation structure in Delta(eta) and Delta(phi) is characterised by a narrow peak at (Delta(eta), Delta(phi)) approximately (0, 0) from jet-like correlations and a long-range structure that persists up to at least |Delta(eta)| = 4. An enhancement of the magnitude of the short-range jet peak is observed with increasing centrality, especially for particles of pt around 1-2 GeV/c. The long-range azimuthal dihadron correlations are extensively studied using a Fourier decomposition analysis. The extracted Fourier coefficients are found to factorise into a product of single-particle azimuthal anisotropies up to pt approximately 3-3.5 GeV/c for at least one particle from each pair, except for the second-order harmonics in the most central PbPb events. Various orders of the single-particle azimuthal anisotropy harmonics are extracted for associated particle pt of 1-3 GeV/c, as a function of the trigger particle pt up to 20 GeV/c and over the full centrality range.

  13. Spin Dependent Transport in Co Nano-Scale Tunnel Junctions

    E-print Network

    Haviland, David

    Spin Dependent Transport in Co Nano-Scale Tunnel Junctions Mattias Urech Section of Nanostructure, Chalmers #12;Abstract Ferromagnetic tunnel junctions have been fabricated, measured and theoretically de-resistors-in-series model. Single-, triple-, and five- junction arrays were fabricated and measured. In or- der to analyze

  14. Temperature dependence of vertical transport in quantum Hall multilayers

    NASA Astrophysics Data System (ADS)

    Walling, H. A.; Dougherty, D. P.; Druist, D. P.; Gwinn, E. G.; Maranowski, K. D.; Gossard, A. C.

    2002-01-01

    We study the temperature dependence of vertical transport in GaAs/Al 0.1Ga 0.9As multilayers, in the regime of the integer quantum Hall effect. At low temperatures, vertical transport in quantum Hall states occurs on a two-dimensional chiral sheath of edge states near the sidewalls of the sample mesas. At higher temperatures, variable-range hopping through the bulk of the sample dominates. To extend the temperature range of sheath-dominated transport, we increase the device perimeters using fractal-shaped mesas defined by e-beam lithography. We report on the freeze-out of bulk transport and the nearly linear increase of the sheath conductivity with temperature.

  15. Azimuth and Altitude

    NSDL National Science Digital Library

    When finding our way through the landscape, we use points of reference to orient ourselves. At sea, navigators use azimuth or bearing to describe the direction and altitude to describe the height of the sun or a star, lighthouse, or buoy used as a point of reference. In this activity students use a compass and their hands to find positions of stars and planets in the night sky or of the sun during the day. Terms introduced include 360 degree circle, azimuth, altitude, and bearing.

  16. Cation-dependent nutrient transport in shrimp digestive tract.

    PubMed

    Simmons, Tamla; Mozo, Julie; Wilson, Jennifer; Ahearn, Gregory A

    2012-02-01

    Purified epithelial brush border membrane vesicles (BBMV) were produced from the hepatopancreas of the Atlantic White shrimp, Litopeneaus setiferus, using standard methods originally developed for mammalian tissues and previously applied to other crustacean and echinoderm epithelia. These vesicles were used to study the cation dependency of sugar and amino acid transport across luminal membranes of hepatopancreatic epithelial cells. (3)H-D: -glucose uptake by BBMV against transient sugar concentration gradients occurred when either transmembrane sodium or potassium gradients were the only driving forces for sugar accumulation, suggesting the presence of a possible coupled transport system capable of using either cation. (3)H-L: -histidine transport was only stimulated by a transmembrane potassium gradient, while (3)H-L: -leucine uptake was enhanced by either a sodium or potassium gradient. These responses suggest the possible presence of a potassium-dependent transporter that accommodates either amino acid and a sodium-dependent system restricted only to L: -leucine. Uptake of (3)H-L: -leucine was significantly stimulated (P < 0.05) by several metallic cations (e.g., Zn(2+), Cu(2+), Mn(2+), Cd(2+), or Co(2+)) at external pH values of 7.0 or 5.0 (internal pH 7.0), suggesting a potential synergistic role of the cations in the transmembrane transfer of amino acids. (3)H-L: -histidine influxes (15 suptakes) were hyperbolic functions of external [zinc] or [manganese], following Michaelis-Menten kinetics. The apparent affinity constant (e.g., K (m)) for manganese was an order of magnitude smaller (K (m) = 0.22 ?M Mn) than that for zinc (K (m) = 1.80 ?M Zn), while no significant difference (P > 0.05) occurred between their maximal transport velocities (e.g., J (max)). These results suggest that a number of cation-dependent nutrient transport systems occur on the shrimp brush border membrane and aid in the absorption of these important dietary elements. PMID:21983793

  17. Anomalous temperature dependence of electrical transport in quantum Hall multilayers

    NASA Astrophysics Data System (ADS)

    Walling, H. A.; Dougherty, D. P.; Druist, D. P.; Gwinn, E. G.; Maranowski, K. D.; Gossard, A. C.

    2004-07-01

    We study the temperature dependence of vertical transport through the chiral sheath of surface states that exists near the sidewalls of GaAs/Al0.01Ga0.09As multilayer structures in the regime of the integer quantum Hall effect. Because variable-range hopping through the bulk provides a parallel conduction channel, we design our experiment to extend the temperature range of sheath-dominated transport. To do so, we increase device perimeter by using fractal-perimeter mesas. We report on the nearly linear increase of the sheath conductivity with temperature, a result not predicted by existing theories for the edge state sheath.

  18. Temperature dependence of electronic transport property in ferroelectric polymer films

    NASA Astrophysics Data System (ADS)

    Zhao, X. L.; Wang, J. L.; Tian, B. B.; Liu, B. L.; Zou, Y. H.; Wang, X. D.; Sun, S.; Sun, J. L.; Meng, X. J.; Chu, J. H.

    2014-10-01

    The leakage current mechanism of ferroelectric copolymer of polyvinylidene fluoride with trifluoroethylene prepared by Langmuir-Blodgett was investigated in the temperature range from 100 K to 350 K. The electron as the dominant injected carrier was observed in the ferroelectric copolymer films. The transport mechanisms in copolymer strongly depend on the temperature and applied voltage. From 100 K to 200 K, Schottky emission dominates the conduction. With temperature increasing, the Frenkel-Poole emission instead of the Schottky emission to conduct the carrier transport. When the temperature gets to 260 K, the leakage current becomes independent of temperature, and the space charge limited current conduction was observed.

  19. Microfluidic-Enabled Liposomes Elucidate Size-Dependent Transdermal Transport

    PubMed Central

    Junqueira, Mariana; Vreeland, Wyatt N.; Quezado, Zenaide; Finkel, Julia C.; DeVoe, Don L.

    2014-01-01

    Microfluidic synthesis of small and nearly-monodisperse liposomes is used to investigate the size-dependent passive transdermal transport of nanoscale lipid vesicles. While large liposomes with diameters above 105 nm are found to be excluded from deeper skin layers past the stratum corneum, the primary barrier to nanoparticle transport, liposomes with mean diameters between 31–41 nm exhibit significantly enhanced penetration. Furthermore, multicolor fluorescence imaging reveals that the smaller liposomes pass rapidly through the stratum corneum without vesicle rupture. These findings reveal that nanoscale liposomes with well-controlled size and minimal size variance are excellent vehicles for transdermal delivery of functional nanoparticle drugs. PMID:24658111

  20. Azimuthal-angle dependence of charged-pion-interferometry measurements with respect to 2$^{\\rm nd}$- and $3^{\\rm rd}$-order event planes in Au$+$Au collisions at $\\sqrt{s_{_{NN}}}=200$ GeV

    E-print Network

    A. Adare; S. Afanasiev; C. Aidala; N. N. Ajitanand; Y. Akiba; H. Al-Bataineh; J. Alexander; K. Aoki; Y. Aramaki; E. T. Atomssa; R. Averbeck; T. C. Awes; B. Azmoun; V. Babintsev; M. Bai; G. Baksay; L. Baksay; K. N. Barish; B. Bassalleck; A. T. Basye; S. Bathe; V. Baublis; C. Baumann; A. Bazilevsky; S. Belikov; R. Belmont; R. Bennett; A. Berdnikov; Y. Berdnikov; A. A. Bickley; J. S. Bok; K. Boyle; M. L. Brooks; H. Buesching; V. Bumazhnov; G. Bunce; S. Butsyk; C. M. Camacho; S. Campbell; C. -H. Chen; C. Y. Chi; M. Chiu; I. J. Choi; R. K. Choudhury; P. Christiansen; T. Chujo; P. Chung; O. Chvala; V. Cianciolo; Z. Citron; B. A. Cole; M. Connors; P. Constantin; M. Csanád; T. Csörg?; T. Dahms; S. Dairaku; I. Danchev; K. Das; A. Datta; G. David; A. Denisov; A. Deshpande; E. J. Desmond; O. Dietzsch; A. Dion; M. Donadelli; O. Drapier; A. Drees; K. A. Drees; J. M. Durham; A. Durum; D. Dutta; S. Edwards; Y. V. Efremenko; F. Ellinghaus; T. Engelmore; A. Enokizono; H. En'yo; S. Esumi; B. Fadem; D. E. Fields; M. Finger; M. Finger; \\, Jr.; F. Fleuret; S. L. Fokin; Z. Fraenkel; J. E. Frantz; A. Franz; A. D. Frawley; K. Fujiwara; Y. Fukao; T. Fusayasu; I. Garishvili; A. Glenn; H. Gong; M. Gonin; Y. Goto; R. Granier de Cassagnac; N. Grau; S. V. Greene; M. Grosse Perdekamp; T. Gunji; H. -Å. Gustafsson; J. S. Haggerty; K. I. Hahn; H. Hamagaki; J. Hamblen; R. Han; J. Hanks; E. P. Hartouni; E. Haslum; R. Hayano; X. He; M. Heffner; T. K. Hemmick; T. Hester; J. C. Hill; M. Hohlmann; W. Holzmann; K. Homma; B. Hong; T. Horaguchi; D. Hornback; S. Huang; T. Ichihara; R. Ichimiya; J. Ide; Y. Ikeda; K. Imai; M. Inaba; D. Isenhower; M. Ishihara; T. Isobe; M. Issah; A. Isupov; D. Ivanischev; B. V. Jacak; J. Jia; J. Jin; B. M. Johnson; K. S. Joo; D. Jouan; D. S. Jumper; F. Kajihara; S. Kametani; N. Kamihara; J. Kamin; J. H. Kang; J. Kapustinsky; K. Karatsu; D. Kawall; M. Kawashima; A. V. Kazantsev; T. Kempel; A. Khanzadeev; K. M. Kijima; B. I. Kim; D. H. Kim; D. J. Kim; E. Kim; E. -J. Kim; S. H. Kim; Y. -J. Kim; E. Kinney; K. Kiriluk; Á. Kiss; E. Kistenev; L. Kochenda; B. Komkov; M. Konno; J. Koster; D. Kotchetkov; A. Kozlov; A. Král; A. Kravitz; G. J. Kunde; K. Kurita; M. Kurosawa; Y. Kwon; G. S. Kyle; R. Lacey; Y. S. Lai; J. G. Lajoie; A. Lebedev; D. M. Lee; J. Lee; K. Lee; K. B. Lee; K. S. Lee; M. J. Leitch; M. A. L. Leite; E. Leitner; B. Lenzi; X. Li; P. Liebing; L. A. Linden Levy; T. Liška; A. Litvinenko; H. Liu; M. X. Liu; B. Love; R. Luechtenborg; D. Lynch; C. F. Maguire; Y. I. Makdisi; A. Malakhov; M. D. Malik; V. I. Manko; E. Mannel; Y. Mao; H. Masui; F. Matathias; M. McCumber; P. L. McGaughey; N. Means; B. Meredith; Y. Miake; A. C. Mignerey; P. Mikeš; K. Miki; A. Milov; M. Mishra; J. T. Mitchell; A. K. Mohanty; Y. Morino; A. Morreale; D. P. Morrison; T. V. Moukhanova; J. Murata; S. Nagamiya; J. L. Nagle; M. Naglis; M. I. Nagy; I. Nakagawa; Y. Nakamiya; T. Nakamura; K. Nakano; J. Newby; M. Nguyen; T. Niida; R. Nouicer; A. S. Nyanin; E. O'Brien; S. X. Oda; C. A. Ogilvie; M. Oka; K. Okada; Y. Onuki; A. Oskarsson; M. Ouchida; K. Ozawa; R. Pak; V. Pantuev; V. Papavassiliou; I. H. Park; J. Park; S. K. Park; W. J. Park; S. F. Pate; H. Pei; J. -C. Peng; H. Pereira; V. Peresedov; D. Yu. Peressounko; C. Pinkenburg; R. P. Pisani; M. Proissl; M. L. Purschke; A. K. Purwar; H. Qu; J. Rak; A. Rakotozafindrabe; I. Ravinovich; K. F. Read; K. Reygers; V. Riabov; Y. Riabov; E. Richardson; D. Roach; G. Roche; S. D. Rolnick; M. Rosati; C. A. Rosen; S. S. E. Rosendahl; P. Rosnet; P. Rukoyatkin; P. Ruži?ka; B. Sahlmueller; N. Saito; T. Sakaguchi; K. Sakashita; V. Samsonov; S. Sano; T. Sato; S. Sawada; K. Sedgwick; J. Seele; R. Seidl; A. Yu. Semenov; R. Seto; D. Sharma; I. Shein; T. -A. Shibata; K. Shigaki; M. Shimomura; K. Shoji; P. Shukla; A. Sickles; C. L. Silva; D. Silvermyr; C. Silvestre; K. S. Sim; B. K. Singh; C. P. Singh; V. Singh; M. Slune?ka; R. A. Soltz; W. E. Sondheim; S. P. Sorensen; I. V. Sourikova; N. A. Sparks; P. W. Stankus; E. Stenlund; S. P. Stoll; T. Sugitate; A. Sukhanov; J. Sziklai; E. M. Takagui; A. Taketani; R. Tanabe; Y. Tanaka; K. Tanida; M. J. Tannenbaum; S. Tarafdar; A. Taranenko; P. Tarján; H. Themann; T. L. Thomas; T. Todoroki; M. Togawa; A. Toia; L. Tomášek; H. Torii; R. S. Towell; I. Tserruya; Y. Tsuchimoto; C. Vale; H. Valle; H. W. van Hecke; E. Vazquez-Zambrano; A. Veicht; J. Velkovska; R. Vértesi; A. A. Vinogradov; M. Virius; V. Vrba; E. Vznuzdaev; X. R. Wang; D. Watanabe; K. Watanabe; Y. Watanabe; F. Wei; R. Wei; J. Wessels; S. N. White; D. Winter; J. P. Wood; C. L. Woody; R. M. Wright; M. Wysocki; W. Xie; Y. L. Yamaguchi; K. Yamaura; R. Yang; A. Yanovich; J. Ying; S. Yokkaichi; Z. You; G. R. Young; I. Younus; I. E. Yushmanov; W. A. Zajc; C. Zhang; S. Zhou; L. Zolin

    2014-01-29

    Charged-pion-interferometry measurements were made with respect to the 2$^{\\rm nd}$- and 3$^{\\rm rd}$-order event plane for Au$+$Au collisions at $\\sqrt{s_{_{NN}}}=200$ GeV. A strong azimuthal-angle dependence of the extracted Gaussian-source radii was observed with respect to both the 2$^{\\rm nd}$- and 3$^{\\rm rd}$-order event planes. The results for the 2$^{\\rm nd}$-order dependence indicate that the initial eccentricity is reduced during the medium evolution, but not reversed in the final state, which is consistent with previous results. In contrast, the results for the 3$^{\\rm rd}$-order dependence indicate that the initial triangular shape is significantly reduced and potentially reversed by the end of the medium evolution, and that the 3$^{\\rm rd}$-order oscillations are largely dominated by the dynamical effects from triangular flow.

  1. Azimuthal-Angle Dependence of Charged-Pion-Interferometry Measurements with Respect to Second- and Third-Order Event Planes in Au +Au Collisions at ?sNN =200 GeV

    NASA Astrophysics Data System (ADS)

    Adare, A.; Afanasiev, S.; Aidala, C.; Ajitanand, N. N.; Akiba, Y.; Al-Bataineh, H.; Alexander, J.; Aoki, K.; Aramaki, Y.; Atomssa, E. T.; Averbeck, R.; Awes, T. C.; Azmoun, B.; Babintsev, V.; Bai, M.; Baksay, G.; Baksay, L.; Barish, K. N.; Bassalleck, B.; Basye, A. T.; Bathe, S.; Baublis, V.; Baumann, C.; Bazilevsky, A.; Belikov, S.; Belmont, R.; Bennett, R.; Berdnikov, A.; Berdnikov, Y.; Bickley, A. A.; Bok, J. S.; Boyle, K.; Brooks, M. L.; Buesching, H.; Bumazhnov, V.; Bunce, G.; Butsyk, S.; Camacho, C. M.; Campbell, S.; Chen, C.-H.; Chi, C. Y.; Chiu, M.; Choi, I. J.; Choudhury, R. K.; Christiansen, P.; Chujo, T.; Chung, P.; Chvala, O.; Cianciolo, V.; Citron, Z.; Cole, B. A.; Connors, M.; Constantin, P.; Csanád, M.; Csörg?, T.; Dahms, T.; Dairaku, S.; Danchev, I.; Das, K.; Datta, A.; David, G.; Denisov, A.; Deshpande, A.; Desmond, E. J.; Dietzsch, O.; Dion, A.; Donadelli, M.; Drapier, O.; Drees, A.; Drees, K. A.; Durham, J. M.; Durum, A.; Dutta, D.; Edwards, S.; Efremenko, Y. V.; Ellinghaus, F.; Engelmore, T.; Enokizono, A.; En'yo, H.; Esumi, S.; Fadem, B.; Fields, D. E.; Finger, M.; Finger, M.; Fleuret, F.; Fokin, S. L.; Fraenkel, Z.; Frantz, J. E.; Franz, A.; Frawley, A. D.; Fujiwara, K.; Fukao, Y.; Fusayasu, T.; Garishvili, I.; Glenn, A.; Gong, H.; Gonin, M.; Goto, Y.; Granier de Cassagnac, R.; Grau, N.; Greene, S. V.; Grosse Perdekamp, M.; Gunji, T.; Gustafsson, H.-Å.; Haggerty, J. S.; Hahn, K. I.; Hamagaki, H.; Hamblen, J.; Han, R.; Hanks, J.; Hartouni, E. P.; Haslum, E.; Hayano, R.; He, X.; Heffner, M.; Hemmick, T. K.; Hester, T.; Hill, J. C.; Hohlmann, M.; Holzmann, W.; Homma, K.; Hong, B.; Horaguchi, T.; Hornback, D.; Huang, S.; Ichihara, T.; Ichimiya, R.; Ide, J.; Ikeda, Y.; Imai, K.; Inaba, M.; Isenhower, D.; Ishihara, M.; Isobe, T.; Issah, M.; Isupov, A.; Ivanischev, D.; Jacak, B. V.; Jia, J.; Jin, J.; Johnson, B. M.; Joo, K. S.; Jouan, D.; Jumper, D. S.; Kajihara, F.; Kametani, S.; Kamihara, N.; Kamin, J.; Kang, J. H.; Kapustinsky, J.; Karatsu, K.; Kawall, D.; Kawashima, M.; Kazantsev, A. V.; Kempel, T.; Khanzadeev, A.; Kijima, K. M.; Kim, B. I.; Kim, D. H.; Kim, D. J.; Kim, E.; Kim, E.-J.; Kim, S. H.; Kim, Y.-J.; Kinney, E.; Kiriluk, K.; Kiss, Á.; Kistenev, E.; Kochenda, L.; Komkov, B.; Konno, M.; Koster, J.; Kotchetkov, D.; Kozlov, A.; Král, A.; Kravitz, A.; Kunde, G. J.; Kurita, K.; Kurosawa, M.; Kwon, Y.; Kyle, G. S.; Lacey, R.; Lai, Y. S.; Lajoie, J. G.; Lebedev, A.; Lee, D. M.; Lee, J.; Lee, K.; Lee, K. B.; Lee, K. S.; Leitch, M. J.; Leite, M. A. L.; Leitner, E.; Lenzi, B.; Li, X.; Liebing, P.; Linden Levy, L. A.; Liška, T.; Litvinenko, A.; Liu, H.; Liu, M. X.; Love, B.; Luechtenborg, R.; Lynch, D.; Maguire, C. F.; Makdisi, Y. I.; Malakhov, A.; Malik, M. D.; Manko, V. I.; Mannel, E.; Mao, Y.; Masui, H.; Matathias, F.; McCumber, M.; McGaughey, P. L.; Means, N.; Meredith, B.; Miake, Y.; Mignerey, A. C.; Mikeš, P.; Miki, K.; Milov, A.; Mishra, M.; Mitchell, J. T.; Mohanty, A. K.; Morino, Y.; Morreale, A.; Morrison, D. P.; Moukhanova, T. V.; Murata, J.; Nagamiya, S.; Nagle, J. L.; Naglis, M.; Nagy, M. I.; Nakagawa, I.; Nakamiya, Y.; Nakamura, T.; Nakano, K.; Newby, J.; Nguyen, M.; Niida, T.; Nouicer, R.; Nyanin, A. S.; O'Brien, E.; Oda, S. X.; Ogilvie, C. A.; Oka, M.; Okada, K.; Onuki, Y.; Oskarsson, A.; Ouchida, M.; Ozawa, K.; Pak, R.; Pantuev, V.; Papavassiliou, V.; Park, I. H.; Park, J.; Park, S. K.; Park, W. J.; Pate, S. F.; Pei, H.; Peng, J.-C.; Pereira, H.; Peresedov, V.; Peressounko, D. Yu.; Pinkenburg, C.; Pisani, R. P.; Proissl, M.; Purschke, M. L.; Purwar, A. K.; Qu, H.; Rak, J.; Rakotozafindrabe, A.; Ravinovich, I.; Read, K. F.; Reygers, K.; Riabov, V.; Riabov, Y.; Richardson, E.; Roach, D.; Roche, G.; Rolnick, S. D.; Rosati, M.; Rosen, C. A.; Rosendahl, S. S. E.; Rosnet, P.; Rukoyatkin, P.; Ruži?ka, P.; Sahlmueller, B.; Saito, N.; Sakaguchi, T.; Sakashita, K.; Samsonov, V.; Sano, S.; Sato, T.; Sawada, S.; Sedgwick, K.; Seele, J.; Seidl, R.; Semenov, A. Yu.; Seto, R.; Sharma, D.; Shein, I.; Shibata, T.-A.; Shigaki, K.; Shimomura, M.; Shoji, K.; Shukla, P.; Sickles, A.; Silva, C. L.; Silvermyr, D.; Silvestre, C.; Sim, K. S.; Singh, B. K.; Singh, C. P.; Singh, V.; Slune?ka, M.; Soltz, R. A.; Sondheim, W. E.; Sorensen, S. P.; Sourikova, I. V.; Sparks, N. A.; Stankus, P. W.; Stenlund, E.; Stoll, S. P.; Sugitate, T.; Sukhanov, A.; Sziklai, J.; Takagui, E. M.; Taketani, A.; Tanabe, R.; Tanaka, Y.; Tanida, K.; Tannenbaum, M. J.; Tarafdar, S.; Taranenko, A.; Tarján, P.; Themann, H.; Thomas, T. L.; Todoroki, T.; Togawa, M.; Toia, A.; Tomášek, L.; Torii, H.; Towell, R. S.; Tserruya, I.; Tsuchimoto, Y.; Vale, C.; Valle, H.; van Hecke, H. W.; Vazquez-Zambrano, E.; Veicht, A.; Velkovska, J.; Vértesi, R.; Vinogradov, A. A.; Virius, M.; Vrba, V.; Vznuzdaev, E.; Wang, X. R.; Watanabe, D.; Watanabe, K.

    2014-06-01

    Charged-pion-interferometry measurements were made with respect to the second- and third-order event plane for Au +Au collisions at ?sNN =200 GeV. A strong azimuthal-angle dependence of the extracted Gaussian-source radii was observed with respect to both the second- and third-order event planes. The results for the second-order dependence indicate that the initial eccentricity is reduced during the medium evolution, which is consistent with previous results. In contrast, the results for the third-order dependence indicate that the initial triangular shape is significantly reduced and potentially reversed by the end of the medium evolution, and that the third-order oscillations are largely dominated by the dynamical effects from triangular flow.

  2. Microtubule-dependent transport and dynamics of vimentin intermediate filaments

    PubMed Central

    Hookway, Caroline; Ding, Liya; Davidson, Michael W.; Rappoport, Joshua Z.; Danuser, Gaudenz; Gelfand, Vladimir I.

    2015-01-01

    We studied two aspects of vimentin intermediate filament dynamics—transport of filaments and subunit exchange. We observed transport of long filaments in the periphery of cells using live-cell structured illumination microscopy. We studied filament transport elsewhere in cells using a photoconvertible-vimentin probe and total internal reflection microscopy. We found that filaments were rapidly transported along linear tracks in both anterograde and retrograde directions. Filament transport was microtubule dependent but independent of microtubule polymerization and/or an interaction with the plus end–binding protein APC. We also studied subunit exchange in filaments by long-term imaging after photoconversion. We found that converted vimentin remained in small clusters along the length of filaments rather than redistributing uniformly throughout the network, even in cells that divided after photoconversion. These data show that vimentin filaments do not depolymerize into individual subunits; they recompose by severing and reannealing. Together these results show that vimentin filaments are very dynamic and that their transport is required for network maintenance. PMID:25717187

  3. Chloride transporter KCC2-dependent neuroprotection depends on the N-terminal protein domain.

    PubMed

    Winkelmann, A; Semtner, M; Meier, J C

    2015-01-01

    Neurodegeneration is a serious issue of neurodegenerative diseases including epilepsy. Downregulation of the chloride transporter KCC2 in the epileptic tissue may not only affect regulation of the polarity of GABAergic synaptic transmission but also neuronal survival. Here, we addressed the mechanisms of KCC2-dependent neuroprotection by assessing truncated and mutated KCC2 variants in different neurotoxicity models. The results identify a threonine- and tyrosine-phosphorylation-resistant KCC2 variant with increased chloride transport activity, but they also identify the KCC2 N-terminal domain (NTD) as the relevant minimal KCC2 protein domain that is sufficient for neuroprotection. As ectopic expression of the KCC2-NTD works independently of full-length KCC2-dependent regulation of Cl(-) transport or structural KCC2 C-terminus-dependent regulation of synaptogenesis, our study may pave the way for a selective neuroprotective therapeutic strategy that will be applicable to a wide range of neurodegenerative diseases. PMID:26043076

  4. The sodium-dependent ascorbic acid transporter family SLC23.

    PubMed

    Bürzle, Marc; Suzuki, Yoshiro; Ackermann, Daniel; Miyazaki, Hiroki; Maeda, Nobuyo; Clémençon, Benjamin; Burrier, Robert; Hediger, Matthias A

    2013-01-01

    Transporters for vitamin C and its oxidized form dehydroascorbic acid (DHA) are crucial to maintain physiological concentrations of this important vitamin that is used in a variety of biochemical processes. The human SLC23 family consists of the Na(+)-dependent vitamin C transporters SVCT1 (encoded by the SLC23A1 gene) and SVCT2 (SLC23A2) as well as an orphan transporter SVCT3 (SLC23A3). Phylogenetically, the SLC23 family belongs to the nucleobase-ascorbate transporter (NAT) family, although no nucleobase transport has yet been demonstrated for the human members of this family. The SVCT1 and SVCT2 transporters are rather specific for ascorbic acid, which is an important antioxidant and plays a crucial role in a many metal-containing enzymes. SVCT1 is expressed predominantly in epithelial tissues such as intestine where it contributes to the supply and maintenance of whole-body ascorbic acid levels. In contrast to various other mammals, humans are not capable of synthesizing ascorbic acid from glucose and therefore the uptake of ascorbic acid from the diet via SVCT1 is essential for maintaining appropriate concentrations of vitamin C in the human body. The expression of SVCT2 is relatively widespread, where it serves to either deliver ascorbic acid to tissues with high demand of the vitamin for enzymatic reactions or to protect metabolically highly active cells or specialized tissues from oxidative stress. The murine Slc23a3 gene encoding the orphan transporter SVCT3 was originally cloned from mouse yolk sac, and subsequent studies showed that it is expressed in the kidney. However, the function of SVCT3 has not been reported and it remains speculative as to whether SVCT3 is a nucleobase transporter. PMID:23506882

  5. The CU 2-D-MAX-DOAS instrument - Part 1: Retrieval of 3-D distributions of NO2 and azimuth-dependent OVOC ratios

    NASA Astrophysics Data System (ADS)

    Ortega, I.; Koenig, T.; Sinreich, R.; Thomson, D.; Volkamer, R.

    2015-06-01

    We present an innovative instrument telescope and describe a retrieval method to probe three-dimensional (3-D) distributions of atmospheric trace gases that are relevant to air pollution and tropospheric chemistry. The University of Colorado (CU) two-dimensional (2-D) multi-axis differential optical absorption spectroscopy (CU 2-D-MAX-DOAS) instrument measures nitrogen dioxide (NO2), formaldehyde (HCHO), glyoxal (CHOCHO), oxygen dimer (O2-O2, or O4), and water vapor (H2O); nitrous acid (HONO), bromine monoxide (BrO), and iodine monoxide (IO) are among other gases that can in principle be measured. Information about aerosols is derived through coupling with a radiative transfer model (RTM). The 2-D telescope has three modes of operation: mode 1 measures solar scattered photons from any pair of elevation angle (-20° < EA < +90° or zenith; zero is to the horizon) and azimuth angle (-180° < AA < +180°; zero being north); mode 2 measures any set of azimuth angles (AAs) at constant elevation angle (EA) (almucantar scans); and mode 3 tracks the direct solar beam via a separate view port. Vertical profiles of trace gases are measured and used to estimate mixing layer height (MLH). Horizontal distributions are then derived using MLH and parameterization of RTM (Sinreich et al., 2013). NO2 is evaluated at different wavelengths (350, 450, and 560 nm), exploiting the fact that the effective path length varies systematically with wavelength. The area probed is constrained by O4 observations at nearby wavelengths and has a diurnal mean effective radius of 7.0 to 25 km around the instrument location; i.e., up to 1960 km2 can be sampled with high time resolution. The instrument was deployed as part of the Multi-Axis DOAS Comparison campaign for Aerosols and Trace gases (MAD-CAT) in Mainz, Germany, from 7 June to 6 July 2013. We present first measurements (modes 1 and 2 only) and describe a four-step retrieval to derive (a) boundary layer vertical profiles and MLH of NO2; (b) near-surface horizontal distributions of NO2; (c) range-resolved NO2 horizontal distribution measurements using an "onion-peeling" approach; and (d) the ratios HCHO to NO2 (RFN), CHOCHO to NO2 (RGN), and CHOCHO to HCHO (RGF) at 14 pre-set azimuth angles distributed over a 360° view. Three-dimensional distribution measurements with 2-D-MAX-DOAS provide an innovative, regional perspective of trace gases as well as their spatial and temporal concentration gradients, and they maximize information to compare near-surface observations with atmospheric models and satellites.

  6. Single-electron approach for time-dependent electron transport

    E-print Network

    Shmuel Gurvitz

    2014-12-03

    We develop a new approach to electron transport in mesoscopic systems by using a particular single-particle basis. Although this basis generates redundant many-particle amplitudes, it greatly simplifies the treatment. By using our method for transport of non-interacting electrons, we generalize the Landauer formula for transient currents and for time-dependent potentials. The result has a very simple form and clear physical interpretation. As an example, we apply it to resonant tunneling through a quantum dot where the tunneling barriers are oscillating in time. We obtain analytical expression for the time-dependent (ac) resonant current. However, in the adiabatic limit this expression displays the dc current for zero bias (electron pumping).

  7. Temperature dependent transport coefficients in a dynamical holographic QCD model

    NASA Astrophysics Data System (ADS)

    Li, Danning; He, Song; Huang, Mei

    2015-06-01

    We investigate temperature dependent behavior of various transport coefficients in a dynamical holographical QCD model. We show the nontrivial temperature dependent behavior of the transport coefficients, like bulk viscosity, electric conductivity as well as jet quenching parameter, and it is found that all these quantities reveal information of the phase transition. Furthermore, with introducing higher derivative corrections in 5D gravity, the shear viscosity over entropy density ratio also shows a valley around phase transition, and it is found that the shear viscosity over entropy density ratio times the jet quenching over temperature cubic ratio almost remains as a constant above phase transition, and the value is two times larger than the perturbative result in Phys.Rev.Lett.99.192301(2007).

  8. Temperature dependent transport coefficients in a dynamical holographic QCD model

    E-print Network

    Danning Li; Song He; Mei Huang

    2014-11-19

    We investigate temperature dependent behavior of various transport coefficients in a dynamical holographical QCD model. We show the nontrivial temperature dependent behavior of the transport coefficients, like bulk viscosity, electric conductivity as well as jet quenching parameter, and it is found that all these quantities reveal information of the phase transition. Furthermore, with introducing higher derivative corrections in 5D gravity, the shear viscosity over entropy density ratio also shows a valley around phase transition, and it is found that the shear viscosity over entropy density ratio times the jet quenching over temperature cubic ratio almost remains as a constant above phase transition, and the value is two times larger than the perturbative result in Phys.Rev.Lett.99.192301(2007).

  9. Interface scattering and spin-dependent transport in granular magnetite

    NASA Astrophysics Data System (ADS)

    Yang, Zhongtian; Zhu, Liya

    2009-07-01

    We have prepared nearly monodisperse Fe 3O 4 of ˜50 nm by a chemical route and investigated the electrical and magnetic transports of the composite granular system. A Verwey transition is observed in the vicinity of 113 K. Above and below the Verwey transition, the electrical transport is dominated by electron hopping behavior showing a good linear relation between resistance and T-1/2. The magnetoresistance (MR) increases with the applied field and does not follow the magnetization to reach the saturation at 10 KOe field. This indicates that the MR is mainly arising from the spin-dependent scattering of electrons through the grain boundaries. The temperature dependence of MR shows it has the highest MR value near the Verwey transition.

  10. On the dependence of the efficiency of a 240?GHz high-power gyrotron on the displacement of the electron beam and on the azimuthal index

    SciTech Connect

    Dumbrajs, O. [Institute of Solid State Physics (ISSP), Association EUROATOM-University of Latvia, Kengaraga iela 8, LV-1063 Riga (Latvia)] [Institute of Solid State Physics (ISSP), Association EUROATOM-University of Latvia, Kengaraga iela 8, LV-1063 Riga (Latvia); Avramidis, K. A.; Franck, J.; Jelonnek, J. [Karlsruhe Institute of Technology (KIT), Institute for Pulsed Power and Microwave Technology (IHM), Association EURATOM-KIT, Kaiserstrasse 12, 76131 Karlsruhe (Germany)] [Karlsruhe Institute of Technology (KIT), Institute for Pulsed Power and Microwave Technology (IHM), Association EURATOM-KIT, Kaiserstrasse 12, 76131 Karlsruhe (Germany)

    2014-01-15

    Two issues in the cavity design for a Megawatt-class, 240?GHz gyrotron are addressed. Those are first, the effect of a misaligned electron beam on the gyrotron efficiency and second, a possible azimuthal instability of the gyrotron. The aforementioned effects are important for any gyrotron operation, but could be more critical in the operation of Megawatt-class gyrotrons at frequencies above 200 GHz, which will be the anticipated requirement of DEMO. The target is to provide some basic trends to be considered during the refinement and optimization of the design. Self-consistent calculations are the base for simulations wherever possible. However, in cases for which self-consistent models were not available, fixed-field results are presented. In those cases, the conservative nature of the results should be kept in mind.

  11. Sodium-dependent ascorbic acid transporter family SLC23

    Microsoft Academic Search

    Hitomi Takanaga; Bryan Mackenzie; Matthias A. Hediger

    2004-01-01

    l-Ascorbic acid (vitamin C) is an effective antioxidant and an essential cofactor in numerous enzymatic reactions. Two Na +-dependent vitamin C transporters (SVCT1 and SVCT2) are members of the SLC23 human gene family, which also contains two orphan members. SVCT1 and SVCT2 display similar properties, including high affinity for l-ascorbic acid, but are discretely distributed. SVCT1 is confined to epithelial

  12. Molecular spintronics: spin-dependent electron transport in molecular wires

    Microsoft Academic Search

    Eldon G. Emberly; George Kirczenow

    2002-01-01

    We present a theoretical study of spin-dependent transport through molecular wires bridging ferromagnetic metal nanocontacts. We extend to magnetic systems a recently proposed model that provides a quantitative explanation of the conductance measurements of Reed et al. [Science 278 (1997) 252] on Au break-junctions bridged by self-assembled molecular monolayers (SAMs) of 1,4-benzene–dithiolate (BDT) molecules. Based on our calculations, we predict

  13. Time-dependent single-electron transport through quantum dots

    Microsoft Academic Search

    Toshimasa Fujisawa; Toshiaki Hayashi; Satoshi Sasaki

    2006-01-01

    We describe time-dependent single-electron transport through quantum dots in the Coulomb blockade regime. Coherent dynamics of a single charge qubit in a double quantum dot is discussed with full one-qubit manipulation. Strength of decoherence is controlled with the applied voltage, but uncontrolled decoherence arises from electron-phonon coupling and background fluctuations. Then energy-relaxation dynamics is discussed for orbital and spin degree

  14. Immunohistochemical localization of Na + -dependent glucose transporter in rat jejunum

    Microsoft Academic Search

    Kuniaki Takata; Toshiko Kasahara; Michihiro Kasahara; Osamu Ezaki; Hiroshi Hirano

    1992-01-01

    Glucose is actively absorbed via a Na+-dependent active glucose transporter (Na-GT) in the small intestine. We raised a polyclonal antibody against the peptide corresponding to amino acids 564–575 of rabbit intestinal Na-GT, and localized it immunohistochemically in the rat jejunum. By means of immunofluorescence staining, Na-GT was located at the brush border of the absorptive epithelial cells of the intestinal

  15. Spin-dependent transport of carriers in semiconductors

    Microsoft Academic Search

    R. Winkler

    2006-01-01

    This article reviews spin-dependent transport of carriers in homogenous three-dimensional and two-dimensional semiconductors. We begin with a discussion of optical orientation of electron spins, which allows both the creation and detection of spin-polarized carriers in semiconductors. Then we review non-equilibrium spin flow including spin drift and diffusion caused by electric fields and concentration gradients. A controlled spin precession is possible

  16. Transport of hydrogen in metals with occupancy dependent trap energies

    SciTech Connect

    Schmid, K., E-mail: klaus.schmid@ipp.mpg.de; Toussaint, U. von; Schwarz-Selinger, T. [Max-Planck-Institut für Plasmaphysik, Boltzmannstraße 2, D-85748 Garching b. München (Germany)

    2014-10-07

    Common diffusion trapping models for modeling hydrogen transport in metals are limited to traps with single de-trapping energies and a saturation occupancy of one. While they are successful in predicting typical mono isotopic ion implantation and thermal degassing experiments, they fail at describing recent experiments on isotope exchange at low temperatures. This paper presents a new modified diffusion trapping model with fill level dependent de-trapping energies that can also explain these new isotope exchange experiments. Density function theory (DFT) calculations predict that even mono vacancies can store between 6 and 12 H atoms with de-trapping energies that depend on the fill level of the mono vacancy. The new fill level dependent diffusion trapping model allows to test these DFT results by bridging the gap in length and time scale between DFT calculations and experiment.

  17. The CU 2-dimensional MAX-DOAS instrument - Part 1: Retrieval of NO2 in 3 dimensions and azimuth dependent OVOC ratios

    NASA Astrophysics Data System (ADS)

    Ortega, I.; Koenig, T.; Sinreich, R.; Thomson, D.; Volkamer, R.

    2014-11-01

    We present an innovative instrument telescope, and describe a retrieval method to probe 3-D distributions of atmospheric trace gases that are relevant to air pollution and tropospheric chemistry. The University of Colorado (CU) two dimensional (2-D) Multi-AXis-Differential Optical Absorption Spectroscopy (CU 2D-MAX-DOAS) instrument measures nitrogen dioxide (NO2), formaldehyde (HCHO), glyoxal (CHOCHO), oxygen dimer (O2-O2, or O4) and water vapor (H2O); also nitrous acid (HONO), bromine monoxide (BrO), iodine monoxide (IO) among other gases can in principle be measured. Information about aerosols is derived through coupling with a radiative transfer model (RTM). The 2-D telescope has 3 modes of operation: (mode 1) measures solar scattered photons from any pair of elevation angle (-20° < EA < +90° or zenith; zero is to the horizon) and azimuth angle (-180° < AA < +180°; zero being North), (mode 2) measures any set of AA at constant EA (almucantar scans); and (mode 3) tracks the direct solar beam via a separate view port. Vertical profiles of trace gases are measured, and used to estimate planetary boundary layer height (PBL). Horizontal distributions are then derived using PBL and parameterization of RTM (Sinreich et al., 2013). NO2 is evaluated at different wavelengths (350, 450, and 560 nm), exploiting the fact that the effective path length varies systematically with wavelength. The area probed is constrained by O4 observations at nearby wavelengths, and has an effective radius of 7.5 to 20 km around the instrument location; i.e., up to 1250 km2 can be sampled near-instantaneously, and with high time resolution. The instrument was deployed as part of the Multi Axis DOAS Comparison campaign for Aerosols and Trace gases (MAD-CAT) in Mainz, Germany from 7 June to 6 July 2013. We present first measurements (modes 1 and 2 only) and describe a four-step retrieval to derive (a) boundary layer vertical profiles of NO2 and PBL; (b) near-surface horizontal distributions of NO2; (c) range resolved NO2 horizontal distribution measurements using an "onion peeling" approach; and (d) the ratios HCHO-to-NO2 (RFN), CHOCHO-to-NO2 (RGN), and CHOCHO-to-HCHO (RGF) at 14 pre-set azimuth angles distributed over a 360° view. 2D-MAX-DOAS provides an innovative, regional perspective about trace gases, their spatial and temporal concentration gradients, and maximizes information to compare near-surface observations with atmospheric models and satellites.

  18. Azimuthal Spoke Propagation in Hall Effect Thrusters

    NASA Technical Reports Server (NTRS)

    Sekerak, Michael J.; Longmier, Benjamin W.; Gallimore, Alec D.; Brown, Daniel L.; Hofer, Richard R.; Polk, James E.

    2013-01-01

    Spokes are azimuthally propagating perturbations in the plasma discharge of Hall Effect Thrusters (HETs) that travel in the E x B direction and have been observed in many different systems. The propagation of azimuthal spokes are investigated in a 6 kW HET known as the H6 using ultra-fast imaging and azimuthally spaced probes. A spoke surface is a 2-D plot of azimuthal light intensity evolution over time calculated from 87,500 frames/s videos. The spoke velocity has been determined using three methods with similar results: manual fitting of diagonal lines on the spoke surface, linear cross-correlation between azimuthal locations and an approximated dispersion relation. The spoke velocity for three discharge voltages (300, 400 and 450 V) and three anode mass flow rates (14.7, 19.5 and 25.2 mg/s) yielded spoke velocities between 1500 and 2200 m/s across a range of normalized magnetic field settings. The spoke velocity was inversely dependent on magnetic field strength for low B-field settings and asymptoted at B-field higher values. The velocities and frequencies are compared to standard drifts and plasma waves such as E x B drift, electrostatic ion cyclotron, magnetosonic and various drift waves. The empirically approximated dispersion relation yielded a characteristic velocity that matched the ion acoustic speed for 5 eV electrons that exist in the near-anode and near-field plume regions of the discharge channel based on internal measurements. Thruster performance has been linked to operating mode where thrust-to-power is maximized when azimuthal spokes are present so investigating the underlying mechanism of spokes will benefit thruster operation.

  19. Influences of electron spin ordering on spin dependent transport

    NASA Astrophysics Data System (ADS)

    Miao, Guo-Xing

    Spintronics is an emerging field in research and technology. The additional spin degree of freedom allows one to design devices with novel and superior performances. A good understanding of the spin transport process is necessary for achieving such goals. In this thesis we investigate the effects of electron spin ordering on spin dependent transport processes in micron-sized devices. In a disordered metallic system, the spontaneous spin ordering leads to an extraordinary Hall voltage transverse to the initial electron transport direction, and the voltage is proportional to the degree of ordering in the spin orientations. We use large amount of doping with heavy impurity atom (Pt) in ferromagnetic metals (Fe, Co, Ni, etc.), as well as reduce the film thickness down to the nanometer range in order to increase spin-orbit scatterings. We have observed record-high Hall slope (22.6muO·cm/T at room temperature). In a well ordered epitaxial rutile system (CrO2/SnO 2), there still exist disorders on the order of ppm levels. The completely polarized spin current forming in the half-metal CrO2 are losing part of their spin polarizations after passing the SnO2 barrier, and limited TMR values (?14%) were observed in CrO2/SnO 2/Co MTJs at l0K. Interestingly, we have observed that the sign of Co spin polarization can be reversed by shifting the surface chemical bonding or applying sufficient bias voltage. The latter is an effect due to the disordered states inside SnO2 barrier. In the case of spin transport that maintains complete spin coherence (CoFeB/MgO/CoFeB), both the spin orientations and the momentum states of electrons are conserved across the MgO barrier, and a significant signal boost is immediately achieved with the realization of coherent spin tunneling. We explain the coexistence of low RA and nearly flat temperature/bias dependence of junction resistance with Butler's model. Detailed analysis on these junctions reveals existence of inelastic tunneling processes despite the nearly perfect band matches. In summary, we have studied spin transport in disordered, ordered, and completely coherent systems, and the manipulation of spin dependent scatterings enables us to achieve effective conversion from spin information into voltage information, which is key to spintronics.

  20. Sodium-dependent bile salt transporters of the SCL10A Transporter Family: More than solute transporters

    PubMed Central

    Anwer, M. Sawkat; Stieger, Bruno

    2013-01-01

    Summary The SLC10A transporter gene family consists of seven members and substrates transported by three members (SLC10A1, SLC10A2 and SLC10A6) are Na+-dependent. SLC10A1 (sodium taurocholate cotransporting polypeptide or NTCP) and SLC10A2 (apical sodium-dependent bile salt transporter or ASBT) transport bile salts and play an important role in maintaining enterohepatic circulation of bile salts. Solutes other than bile salts are also transported by NTCP. However, ASBT has not been shown to be a transporter for non-bile salt substrates. While the transport function of NTCP can potentially be used as liver function test, interpretation of such a test may be complicated by altered expression of NTCP in diseases and presence of drugs that may inhibit NTCP function. Transport of bile salts by NTCP and ASBT is inhibited by a number of drugs and it appears that ASBT is more permissive to drug inhibition than NTCP. The clinical significance of this inhibition in drug disposition and drug-drug interaction remains to be determined. Both NCTP and ASBT undergo post-translational regulations that involve phosphorylation/dephosphorylation, translocation to and retrieval from the plasma membrane and degradation by the ubiquitin-proteasome system. These posttranslational regulations are mediated via signaling pathways involving cAMP, calcium, nitric oxide, phosphoinositide-3-kinase (PI3K), protein kinase C (PKC) and protein phosphatases. There appears to be species difference in the substrate specificity and the regulation of plasma membrane localization of human and rodent NTCP. These differences should be taken into account when extrapolating rodent data for human clinical relevance and developing novel therapies. NTCP has recently been shown to play an important role in HBV and HDV infection by serving as a receptor for entry of these viruses into hepatocytes. PMID:24196564

  1. Azimuthal Anisotropy of {pi}{sup 0} Production in Au+Au Collisions at {radical}(s{sub NN})=200 GeV: Path-Length Dependence of Jet Quenching and the Role of Initial Geometry

    SciTech Connect

    Adare, A.; Bickley, A. A.; Ellinghaus, F.; Glenn, A.; Kinney, E.; Kiriluk, K.; Linden Levy, L. A.; Nagle, J. L.; Rosen, C. A.; Seele, J.; Wysocki, M. [University of Colorado, Boulder, Colorado 80309 (United States); Afanasiev, S.; Isupov, A.; Litvinenko, A.; Malakhov, A.; Peresedov, V.; Rukoyatkin, P.; Zolin, L. [Joint Institute for Nuclear Research, 141980 Dubna, Moscow Region (Russian Federation); Aidala, C.; Datta, A. [Department of Physics, University of Massachusetts, Amherst, Massachusetts 01003-9337 (United States)

    2010-10-01

    We have measured the azimuthal anisotropy of {pi}{sup 0} production for 1dependence steeper than what is implied by current PQCD energy-loss models show reasonable agreement with the data.

  2. Technology of optical azimuth transmission

    NASA Astrophysics Data System (ADS)

    Lu, Honggang; Hu, Chunsheng; Wang, Xingshu; Gao, Yang

    2012-11-01

    It often needs transfer a reference from one place to another place in aerospace and guided missile launching. At first, principles of several typical optical azimuth transmission methods are presented. Several typical methods are introduced, such as Theodolite (including gyro-theodolite) collimation method, Camera series method, Optical apparatus for azimuth method and polarization modulated light transmission method. For these typical azimuth transmission methods, their essential theories are elaborated. Then the devices, the application fields and limitations of these typical methods' are presented. Theodolite (including gyro-theodolite) collimation method is used in the ground assembly of spacecraft. Camera series method and optical apparatus for azimuth method are used in azimuth transmission between different decks of ship. Polarization modulated light transmission method is used in azimuth transmission of rocket and guided missile. At the last, the further developments of these methods are discussed.

  3. Development of a cyclin-dependent kinase inhibitor devoid of ABC transporter-dependent drug resistance

    PubMed Central

    Kaliszczak, M; Patel, H; Kroll, S H B; Carroll, L; Smith, G; Delaney, S; Heathcote, D A; Bondke, A; Fuchter, M J; Coombes, R C; Barrett, A G M; Ali, S; Aboagye, E O

    2013-01-01

    Background: Cyclin-dependent kinases (CDKs) control cell cycle progression, RNA transcription and apoptosis, making them attractive targets for anticancer drug development. Unfortunately, CDK inhibitors developed to date have demonstrated variable efficacy. Methods: We generated drug-resistant cells by continuous low-dose exposure to a model pyrazolo[1,5-a]pyrimidine CDK inhibitor and investigated potential structural alterations for optimal efficacy. Results: We identified induction of the ATP-binding cassette (ABC) transporters, ABCB1 and ABCG2, in resistant cells. Assessment of features involved in the ABC transporter substrate specificity from a compound library revealed high polar surface area (>100?Å2) as a key determinant of transporter interaction. We developed ICEC-0782 that preferentially inhibited CDK2, CDK7 and CDK9 in the nanomolar range. The compound inhibited phosphorylation of CDK substrates and downregulated the short-lived proteins, Mcl-1 and cyclin D1. ICEC-0782 induced G2/M arrest and apoptosis. The permeability and cytotoxicity of ICEC-0782 were unaffected by ABC transporter expression. Following daily oral dosing, the compound inhibited growth of human colon HCT-116 and human breast MCF7 tumour xenografts in vivo by 84% and 94%, respectively. Conclusion: We identified a promising pyrazolo[1,5-a]pyrimidine compound devoid of ABC transporter interaction, highly suitable for further preclinical and clinical evaluation for the treatment of cancer. PMID:24071597

  4. Size dependent transport of amorphous Indium Oxide films.

    NASA Astrophysics Data System (ADS)

    Soman, Swati; Shahar, Dan

    2009-03-01

    Superconductivity in presence of disorder is a topic of interest among experimentalists as well as theoreticians for past several decades. Experiments performed on disordered films of various materials, elemental as well as mixture, have demonstrated Superconductor to Insulator transition (SIT) with increase in disorder or externally applied magnetic field. Disorder is difficult to quantify. However, in an experiment it is controlled by tuning film thickness and/or composition. We present experimental evidence of SIT, in disordered, amorphous Indium Oxide (a:InOx) films, which is tuned by films' lateral dimensions. By fabricating films of same thickness and composition in Hall bar geometry and changing only the sizes of Hall bars, we observe that the sheet resistance per square, R changes with the size of the square, contrary to its definition. The systematic dependence of R on square size is observed to occur only for a critical disorder, similar to percolation model. The observations suggest an inhomogeneous nature of transport near SIT in our samples which are found to be structurally homogeneous. We postulate that such size dependent transport properties are possible to observe in disordered films of other materials that exhibit SIT.

  5. Structure and function of mammalian sodium-dependent multivitamin transporter.

    PubMed

    Prasad, P D; Ganapathy, V

    2000-07-01

    This review focuses on the advances made in recent years in the understanding of the multivitamin transporter, a unique and important transporter that transports not one but three different unrelated water-soluble vitamins namely, pantothenate, biotin and lipoate. The transport process mediated by the transporter is active and is energized by the transmembrane sodium ion gradient as well as the membrane potential. The transporter belongs to the sodium-coupled glucose transporter family. The ubiquitous expression of this transporter in mammalian tissues and the fact that it is highly conserved across the species indicate the nutritional relevance and importance of this transporter. PMID:10929671

  6. Dimensional dependence of phonon transport in freestanding atomic layer systems

    NASA Astrophysics Data System (ADS)

    Kim, Duckjong; Hwangbo, Yun; Zhu, Lijing; Mag-Isa, Alexander E.; Kim, Kwang-Seop; Kim, Jae-Hyun

    2013-11-01

    Due to the fast development of nanotechnology, we have the capability of manipulating atomic layer systems such as graphene, hexagonal boron nitride and dichalcogenides. The major concern in the 2-dimensional nanostructures is how to preserve their exceptional single-layer properties in 3-dimensional bulk structures. In this study, we report that the extreme phonon transport in graphene is highly affected by the graphitic layer stacking based on experimental investigation of the thermal conduction in few-layer graphene, 1-7 layers thick, suspended over holes of various diameters. We fabricate freestanding axisymmetric graphene structures without any perturbing substrate, and measure the in-plane transport property in terms of thermal conduction by using Raman spectroscopy. From the difference in susceptibility to substrate effect, size effect on hot-spot temperature variation and layer number dependence of thermal conductivity, we show that the graphitic membranes with 2 or more layers have characteristics similar to 3-dimensional graphite, which are very different from those of 2-dimensional graphene membranes. This implies that the scattering of out-of-plane phonons by interlayer atomic coupling could be a key mechanism governing the intrinsic thermal property.Due to the fast development of nanotechnology, we have the capability of manipulating atomic layer systems such as graphene, hexagonal boron nitride and dichalcogenides. The major concern in the 2-dimensional nanostructures is how to preserve their exceptional single-layer properties in 3-dimensional bulk structures. In this study, we report that the extreme phonon transport in graphene is highly affected by the graphitic layer stacking based on experimental investigation of the thermal conduction in few-layer graphene, 1-7 layers thick, suspended over holes of various diameters. We fabricate freestanding axisymmetric graphene structures without any perturbing substrate, and measure the in-plane transport property in terms of thermal conduction by using Raman spectroscopy. From the difference in susceptibility to substrate effect, size effect on hot-spot temperature variation and layer number dependence of thermal conductivity, we show that the graphitic membranes with 2 or more layers have characteristics similar to 3-dimensional graphite, which are very different from those of 2-dimensional graphene membranes. This implies that the scattering of out-of-plane phonons by interlayer atomic coupling could be a key mechanism governing the intrinsic thermal property. Electronic supplementary information (ESI) available: Additional figures and table on the sample preparation and the investigation of the PMMA residue on the graphene surface. See DOI: 10.1039/c3nr04000c

  7. Length-dependent thermal transport and ballistic thermal conduction

    NASA Astrophysics Data System (ADS)

    Huang, Bor-Woei; Hsiao, Tzu-Kan; Lin, Kung-Hsuan; Chiou, Dah-Wei; Chang, Chih-Wei

    2015-05-01

    Probing length-dependent thermal conductivity of a given material has been considered as an important experimental method to determine the length of ballistic thermal conduction, or equivalently, the averaged phonon mean free path (l). However, many previous thermal transport measurements have focused on varying the lateral dimensions of samples, rendering the experimental interpretation indirect. Moreover, deducing l is model-dependent in many optical measurement techniques. In addition, finite contact thermal resistances and variations of sample qualities are very likely to obscure the effect in practice, leading to an overestimation of l. We point out that directly investigating one-dimensional length-dependent (normalized) thermal resistance is a better experimental method to determine l. In this regard, we find that no clear experimental data strongly support ballistic thermal conduction of Si or Ge at room temperature. On the other hand, data of both homogeneously-alloyed SiGe nanowires and heterogeneously-interfaced Si-Ge core-shell nanowires provide undisputed evidence for ballistic thermal conduction over several micrometers at room temperature.

  8. Direct method for calculating temperature-dependent transport properties

    NASA Astrophysics Data System (ADS)

    Liu, Yi; Yuan, Zhe; Wesselink, R. J. H.; Starikov, Anton A.; van Schilfgaarde, Mark; Kelly, Paul J.

    2015-06-01

    We show how temperature-induced disorder can be combined in a direct way with first-principles scattering theory to study diffusive transport in real materials. Excellent (good) agreement with experiment is found for the resistivity of Cu, Pd, Pt (and Fe) when lattice (and spin) disorder are calculated from first principles. For Fe, the agreement with experiment is limited by how well the magnetization (of itinerant ferromagnets) can be calculated as a function of temperature. By introducing a simple Debye-like model of spin disorder parameterized to reproduce the experimental magnetization, the temperature dependence of the average resistivity, the anisotropic magnetoresistance, and the spin polarization of a Ni80Fe20 alloy are calculated and found to be in good agreement with existing data. Extension of the method to complex, inhomogeneous materials as well as to the calculation of other finite-temperature physical properties within the adiabatic approximation is straightforward.

  9. Dimensional dependence of phonon transport in freestanding atomic layer systems.

    PubMed

    Kim, Duckjong; Hwangbo, Yun; Zhu, Lijing; Mag-Isa, Alexander E; Kim, Kwang-Seop; Kim, Jae-Hyun

    2013-12-01

    Due to the fast development of nanotechnology, we have the capability of manipulating atomic layer systems such as graphene, hexagonal boron nitride and dichalcogenides. The major concern in the 2-dimensional nanostructures is how to preserve their exceptional single-layer properties in 3-dimensional bulk structures. In this study, we report that the extreme phonon transport in graphene is highly affected by the graphitic layer stacking based on experimental investigation of the thermal conduction in few-layer graphene, 1-7 layers thick, suspended over holes of various diameters. We fabricate freestanding axisymmetric graphene structures without any perturbing substrate, and measure the in-plane transport property in terms of thermal conduction by using Raman spectroscopy. From the difference in susceptibility to substrate effect, size effect on hot-spot temperature variation and layer number dependence of thermal conductivity, we show that the graphitic membranes with 2 or more layers have characteristics similar to 3-dimensional graphite, which are very different from those of 2-dimensional graphene membranes. This implies that the scattering of out-of-plane phonons by interlayer atomic coupling could be a key mechanism governing the intrinsic thermal property. PMID:24126813

  10. pH dependence and compartmentalization of zinc transported across plasma membrane of rat cortical neurons

    E-print Network

    pH dependence and compartmentalization of zinc transported across plasma membrane of rat corticalH dependence and compartmental- ization of zinc transported across plasma membrane of rat cortical neurons. Am. 00143.2001.--In this study, Zn2 transport in rat cortical neurons was characterized by successfully

  11. From Bacteria to Man: Archaic Proton-Dependent Peptide Transporters at Work

    NSDL National Science Digital Library

    PhD Hannelore Daniel (Technical University of Munich Dept of Nut'l Scis-Ernaehrungs-Physiol)

    2006-04-01

    The present review focuses on the electrogenic peptide transporters as the best studied examples of proton-dependent nutrient transporters in mammals and summarizes the most recent findings on their physiological importance. Taking peptide transport as a general phenomenon found in nature, we also include peptide transport mechanisms in bacteria, yeast, invertebrates, and lower vertebrates, which are not that often addressed in physiology journals.

  12. Time Dependent Coherent Electron Transport in Low Dimensional Structures.

    NASA Astrophysics Data System (ADS)

    Foden, Clare Louise

    1990-01-01

    Available from UMI in association with The British Library. Requires signed TDF. In recent years there has been a great deal of interest shown in the vertical transport properties of Low Dimensional Structures. A multitude of different devices have been designed, and their characteristics determined experimentally. Subsequently, there have been many attempts to model theoretically the behaviour of such devices, some more successfully than others. A major stumbling block however remains; the need for answers to various fundamental questions concerning the time-dependence of, and time scales associated with the quantum mechanical behaviour of electrons in a system in which the potential is piecewise constant. However, in non-relativistic quantum mechanics, time has a different status to other dynamical variables, so although it may be possible to calculate and even measure the time dependence of certain quantities, it may not be possible to make direct calculations and measurements of actual times. Thus these fundamental questions have given rise to a multitude of theories, some of which are discussed in the thesis, and all of which are surrounded by controversy. The thesis describes, in detail, theoretical studies on various simple one dimensional models of devices. The first main question addressed is that of how long it takes for an electron to tunnel through a potential barrier, leading on to the second section which comprises of an analysis of whether it is possible to make a measurement of such a time. The latter part of the thesis deals with resonant tunnelling behaviour. The technique used to investigate the electronic motion is an explicitly time dependent one, solving algebraically for the temporal evolution of a wave packet as it traverses the various systems under study. Therefore it may be expected intuitively to give more reasonable solutions to the questions it is attempting to answer than the usual time independent studies.

  13. Precision stationkeeping with azimuthing thrusters

    E-print Network

    Doroski, Adam D

    2011-01-01

    Precision positioning of an unmanned surface vehicle (USV) in a nautical environment is a difficult task. With a dual azimuthing thruster scheme, the optimization of thruster outputs uses an online method to minimize the ...

  14. Gymnemic acids inhibit sodium-dependent glucose transporter 1.

    PubMed

    Wang, Yu; Dawid, Corinna; Kottra, Gabor; Daniel, Hannelore; Hofmann, Thomas

    2014-06-25

    To evaluate the activity of botanicals used in Chinese Traditional Medicine as hypoglycemic agents for diabetes type II prevention and/or treatment, extracts prepared from 26 medicinal herbs were screened for their inhibitory activity on sodium-dependent glucose transporter 1 (SGLT1) by using two-electrode voltage-clamp recording of glucose uptake in Xenopus laevis oocytes microinjected with cRNA for SGLT1. Showing by far the strongest SGLT1 inhibitory effect, the phytochemicals extracted from Gymnema sylvestre (Retz.) Schult were located by means of activity-guided fractionation and identified as 3-O-?-D-glucuronopyranosyl-21-O-2-tigloyl-22-O-2-tigloyl gymnemagenin (1) and 3-O-?-D-glucuronopyranosyl-21-O-2-methylbutyryl-22-O-2-tigloyl gymnemagenin (2) by means of LC-MS/MS, UPLC-TOF/MS, and 1D/2D-NMR experiments. Both saponins exhibited low IC50 values of 5.97 (1) and 0.17 ?M (2), the latter of which was in the same range as found for the high-affinity inhibitor phlorizin (0.21 ?M). As SGLT1 is found in high levels in brush-border membranes of intestinal epithelial cells, these findings demonstrate for the first time the potential of these saponins for inhibiting electrogenic glucose uptake in the gastrointestinal tract. PMID:24856809

  15. Kinesin-1/Hsc70-dependent mechanism of slow axonal transport and its relation to fast axonal transport.

    PubMed

    Terada, Sumio; Kinjo, Masataka; Aihara, Makoto; Takei, Yosuke; Hirokawa, Nobutaka

    2010-02-17

    Cytoplasmic protein transport in axons ('slow axonal transport') is essential for neuronal homeostasis, and involves Kinesin-1, the same motor for membranous organelle transport ('fast axonal transport'). However, both molecular mechanisms of slow axonal transport and difference in usage of Kinesin-1 between slow and fast axonal transport have been elusive. Here, we show that slow axonal transport depends on the interaction between the DnaJ-like domain of the kinesin light chain in the Kinesin-1 motor complex and Hsc70, scaffolding between cytoplasmic proteins and Kinesin-1. The domain is within the tetratricopeptide repeat, which can bind to membranous organelles, and competitive perturbation of the domain in squid giant axons disrupted cytoplasmic protein transport and reinforced membranous organelle transport, indicating that this domain might have a function as a switchover system between slow and fast transport by Hsc70. Transgenic mice overexpressing a dominant-negative form of the domain showed delayed slow transport, accelerated fast transport and optic axonopathy. These findings provide a basis for the regulatory mechanism of intracellular transport and its intriguing implication in neuronal dysfunction. PMID:20111006

  16. Kinesin-1/Hsc70-dependent mechanism of slow axonal transport and its relation to fast axonal transport

    PubMed Central

    Terada, Sumio; Kinjo, Masataka; Aihara, Makoto; Takei, Yosuke; Hirokawa, Nobutaka

    2010-01-01

    Cytoplasmic protein transport in axons (‘slow axonal transport') is essential for neuronal homeostasis, and involves Kinesin-1, the same motor for membranous organelle transport (‘fast axonal transport'). However, both molecular mechanisms of slow axonal transport and difference in usage of Kinesin-1 between slow and fast axonal transport have been elusive. Here, we show that slow axonal transport depends on the interaction between the DnaJ-like domain of the kinesin light chain in the Kinesin-1 motor complex and Hsc70, scaffolding between cytoplasmic proteins and Kinesin-1. The domain is within the tetratricopeptide repeat, which can bind to membranous organelles, and competitive perturbation of the domain in squid giant axons disrupted cytoplasmic protein transport and reinforced membranous organelle transport, indicating that this domain might have a function as a switchover system between slow and fast transport by Hsc70. Transgenic mice overexpressing a dominant-negative form of the domain showed delayed slow transport, accelerated fast transport and optic axonopathy. These findings provide a basis for the regulatory mechanism of intracellular transport and its intriguing implication in neuronal dysfunction. PMID:20111006

  17. Spin-dependent heat transport and thermal boundary resistance

    NASA Astrophysics Data System (ADS)

    Jeong, Taehee

    In this thesis, thermal conductivity change depending on the magnetic configurations has been studied. In order to make different magnetic configurations, we developed a spin valve structure, which has high MR ratio and low saturation field. The high MR ratio was achieved using Co/Cu multilayer and 21A or 34A thick Cu layer. The low saturation field was obtained by implementing different coercivities of the successive ferromagnetic layers. For this purpose, Co/Cu/Cu tri-layered structure was used with the thicknesses of the Co layers; 15 A and 30 A. For the thermal conductivity measurement, a three-omega method was employed with a thermally isolated microscale rod. We fabricated the microscale rod using optical lithography and MEMS process. Then the rod was wire-bonded to a chip-carver for further electrical measurement. For the thermal conductivity measurement, we built the three-omega measurement system using two lock-in amplifiers and two differential amplifiers. A custom-made electromagnet was added to the system to investigate the impact of magnetic field. We observed titanic thermal conductivity change depending on the magnetic configurations of the Co/Cu/Co multilayer. The thermal conductivity change was closely correlated with that of the electric conductivity in terms of the spin orientation, but the thermal conductivity was much more sensitive than that of the electric conductivity. The relative thermal conductivity change was 50% meanwhile that of electric resistivity change was 8.0%. The difference between the two ratios suggests that the scattering mechanism for charge and heat transport in the Co/Cu/Co multilayer is different. The Lorentz number in Weidemann-Franz law is also spin-dependent. Thermal boundary resistance between metal and dielectrics was also studied in this thesis. The thermal boundary resistance becomes critical for heat transport in a nanoscale because the thermal boundary resistance can potentially determine overall heat transport in thin film structures. A transient theraroreflectance (TTR) technique can be used for measuring the thermal conductivity of thin films in cross-sectional direction. In this study, a pump-probe scheme was employed for the TTR technique. We built an optical pump-probe system by using a nanosecond pulse laser for pumping and a continuous-wave laser for probing. A short-time heating event occured at the surface of a sample by shining a laser pulse on the surface. Then the time-resolved thermoreflectance signals were detected using a photodetector and an oscilloscope. The increased temperature decreases slowly and its thermal decay depends on the thermal properties of a sample. Since the reflectivity is linearly proportional to the temperature, the time-resolved thermoreflectance signals have the information of the thermal properties of a sample. In order to extract the thermal properties of a sample, a thermal analysis was performed by fitting the experimental data with thermal models. We developed 2-layered and 3-layered thermal models using the analogies between thermal conduction and electric conduction and a transmission-line concept. We used two sets of sample structures: Au/SiNx/Si substrate and Au/CoFe/SiNx/Si substrate with various thickness of SiN x layer. Using the pump-probe system, we measured the time-resolved thermoreflectance signals for each sample. Then, the thermal conductivity and thermal boundary resistance were obtained by fitting the experimental data with the thermal models. The thermal conductivity of SiNx films was measured to be 2.0 W/mK for both structures. In the case of the thermal boundary resistance, it was 0.81x10-5 m 2K/W at the Au/SiNx interface and 0.54x10 -5 m2K/W at the CoFe/SiNx interface, respectively. The difference of the thermal boundary resistance between Au/SiNx and CoFe/SiNx might be came from the different phonon dispersion of Au and CoFe. The thermal conductivity did not depend on the thickness of SiNx films in the thickness range of 50-200nm. However, the thermal boundary resistance at metal/SiNx interfaces will impa

  18. Temperature-dependent thermal transport properties of Archean rocks

    NASA Astrophysics Data System (ADS)

    Merriman, J. D.; Hofmeister, A.; Nabelek, P. I.; Whittington, A. G.; Benn, K.

    2010-12-01

    Heat transfer controls the rates and styles of fundamental planetary processes including the formation and differentiation of planetary crust, the rheological behavior of the lithosphere and asthenosphere, and the secular cooling of the Earth following its accretion. The Earth's first few hundred million years were characterized by much higher radiogenic heat production and heat flow out of the mantle than seen today, and early continental crust was comprised of rock associations such as granite-greenstone belts and intrusions of tonalite-trondhjemite-granodiorite (TTG). The composition of Archean crustal rocks, and likely variations in radiogenic heat production, have been well documented in past studies. However, the thermal transport properties of these rocks, thermal diffusivity D and thermal conductivity (k=D?CP, where ? is density and CP is isobaric heat capacity), are less well constrained, especially at high temperatures. High temperature measurements of D and k are few, and contact methods may suffer from a combination of imperfect physical contacts and unwanted direct radiative transfer. Using the laser flash analysis (LFA) technique, we determined D of a suite of 14 granite-greenstone and TTG rocks including samples from the Abitibi and Barberton greenstone belts, over a range of crustal temperatures at atmospheric pressure. Dehydration and devolatilization of amphiboles and biotite prevented direct measurement of D for most samples above ~750K, however previous studies of T-dependent D have shown that values of bulk rock diffusivity asymptotically approach a constant value above the ?-? quartz transition (846K). Our measurements yielded a range of D at room temperature from ~3.8 mm2 s-1 for banded iron to ~1 mm2 s-1 for granodiorite. D for all samples decreases with increasing T, and the range of D for the suite narrows to ~0.45 and 0.70 mm2 s-1 for granodiorite and tholeiite basalt respectively by ~1000K. Density of each sample was measured using the Archimedean method and was assumed ~constant over crustal P and T. The T-dependence of CP was calculated from modal mineralogy and published CP data for mineral end-members. Calculated values of k ranged from ~5.7 Wm-1k-1 for a quartz-rich (~38%) tonalite to ~1.7 Wm-1k-1 for a quartz-free syenite at 280K. The range of k at higher temperatures is less restricted than D, as a result of the general increase in CP at higher temperatures and varied between ~2.5 Wm-1k-1 for amphibolite and ~1.5 Wm-1k-1 for syenite. These results show that the T-dependence of D and k cannot be ignored, and variations in thermal transport properties between different rock types, and for a single rock type at different temperatures, may be more important than differences in their radiogenic heat production. This has important implications for the geothermal gradient of Archean crust, its rheological behavior and potential for partial melting.

  19. Transport Through a Clay Barrier with the Contaminant Concentration Dependent Permeability

    Microsoft Academic Search

    Mariusz Kaczmarek; Tomasz Hueckel; Vikas Chawla; Pierluigi Imperiali

    1997-01-01

    Transport of contaminants through clays is characterized by a very low dispersivity, but depends on the sensitivity of its intrinsic permeability to the contaminant's concentration. An additional constitutive relationship for a variable intrinsic permeability is thus adopted leading to a coupled system of equations for diffusive–advective transport in multicomponent liquid. A one-dimensional transport problem is solved using finite difference and

  20. Analytical solution for one-dimensional advection-dispersion transport equation with distance-dependent coefficients

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Mathematical models describing contaminant transport in heterogeneous porous media are often formulated as an advection-dispersion transport equation with distance-dependent transport coefficients. In this work, a general analytical solution is presented for the linear, one-dimensional advection-di...

  1. Hillslope evolution by nonlinear, slope-dependent transport: Steady state morphology and equilibrium adjustment timescales

    Microsoft Academic Search

    Joshua J. Roering; James W. Kirchner; William E. Dietrich

    2001-01-01

    Soil-mantled hillslopes are typically convex near the crest and become increasingly planar downslope, consistent with nonlinear, slope-dependent sediment transport models. In contrast to the widely used linear transport model (in which sediment flux is proportional to slope angle), nonlinear models imply that sediment flux should increase rapidly as hillslope gradient approaches a critical value. Here we explore how nonlinear transport

  2. Renal transport of neutral amino acids. Tubular localization of Na+-dependent phenylalanine- and glucose-transport systems.

    PubMed Central

    Kragh-Hansen, U; Røigaard-Petersen, H; Jacobsen, C; Sheikh, M I

    1984-01-01

    The transport properties for phenylalanine and glucose in luminal-membrane vesicles from outer cortex (pars convoluta) and outer medulla (pars recta) of rabbit kidney were studied by a spectrophotometric method. Uptake of phenylalanine as well as of glucose by the two types of membrane vesicles was found to be Na+-dependent, electrogenic and stereospecific. Na+-dependent transport of L-phenylalanine by outer-cortical membrane vesicles could be accounted for by one transport system (KA congruent to 1.5 mM). By contrast, in the outer-medullary preparation, L-phenylalanine transport occurred via two transport systems, namely a high-affinity system with K1A congruent to 0.33 mM and a low-affinity system with K2A congruent to 7 mM respectively. Na+-dependent uptake of D-glucose by pars convoluta and pars recta membrane vesicles could be described by single, but different, transport systems, namely a low-affinity system with KA congruent to 3.5 mM and a high-affinity system with KA congruent to 0.30 mM respectively. Attempts to calculate the stoichiometry of the different Na+/D-glucose transport systems by using Hill-type plots revealed that the ratio of the Na+/hexose co-transport probably is 1:1 in the case of pars convoluta and 2:1 in membrane vesicles from pars recta. The Na+/L-phenylalanine stoichiometry of the pars convoluta transporter probably is 1:1. Both the high-affinity and the low-affinity Na+-dependent L-phenylalanine transport system of pars recta membrane vesicles seem to operate with a 1:1 stoichiometry. The physiological importance of the arrangement of low-affinity and high-affinity transport systems along the kidney proximal tubule is discussed. Images Fig. 1. PMID:6743259

  3. Salt Dependence of Ion Transport and DNA Translocation through Solid-State

    E-print Network

    Dekker, Cees

    Salt Dependence of Ion Transport and DNA Translocation through Solid-State Nanopores Ralph M. M of the salt dependence of ion transport and DNA translocation through solid-state nanopores. The ionic salt concentrations. DNA translocation is shown to result in either a decrease ([KCl] > 0.4 M

  4. Reduced Dopamine Transporter Availability and Neurocognitive Deficits in Male Patients with Alcohol Dependence

    PubMed Central

    Yen, Che-Hung; Yeh, Yi-Wei; Liang, Chih-Sung; Ho, Pei-Shen; Kuo, Shin-Chang; Huang, Chang-Chih; Chen, Chun-Yen; Shih, Mei-Chen; Ma, Kuo-Hsing; Peng, Giia-Sheun; Lu, Ru-Band; Huang, San-Yuan

    2015-01-01

    Dopamine plays an important role in the development of alcohol dependence, cognitive dysfunction, and is regulated via dopamine transporter activity. Although dopamine transporter activity is critically involved in alcohol dependence, studies observing this relationship are limited. Thus the current study examined whether dopamine transporter availability is associated with developing of alcohol dependence and cognitive dysfunction. Brain imaging with 99mTc-TRODAT-1 as a ligand was used to measure dopamine transporter availability among 26 male patients with pure alcohol dependence and 22 age- and sex- matched healthy volunteers. The Wisconsin Card Sorting Test (WCST) and Tridimensional Personality Questionnaire (TPQ) were administered to assess neurocognitive functioning and personality traits, respectively. Compared to healthy controls, patients with alcohol dependence showed a significant reduction in dopamine transporter availability (p < 0.001), as well as diminished performance on the WCST (p < 0.001). Dopamine transporter availability was negatively correlated with both total and perseverative WCST errors among healthy controls, but only patients with alcohol dependence showed a positive correlation between dopamine transporter availability and a harm avoidance personality profile. Thus, reductions in dopamine transporter availability may play a pathophysiological role in the development of pure alcohol dependence, given its association with neurocognitive deficits. Moreover, personality may influence the development of pure alcohol dependence; however, additional clinical subgroups should be examined to confirm this possibility. PMID:26120847

  5. ATP-Dependent Silver Transport across the Basolateral Membrane of Rainbow Trout Gills

    E-print Network

    Grosell, Martin

    ATP-Dependent Silver Transport across the Basolateral Membrane of Rainbow Trout Gills N. R. Bury Received February 2, 1999; accepted May 19, 1999 ATP-Dependent Silver Transport across the Basolateral Mem. Appl. Pharmacol. 159, 1­8. Silver has been shown to be extremely toxic to freshwater teleosts, acting

  6. Association of serotonin transporter gene polymorphism with nicotine dependence: no evidence for an interaction

    E-print Network

    Association of serotonin transporter gene polymorphism with nicotine dependence: no evidence. Nicotine dependence was measured using the Fag- erstro¨m Test for Nicotine Dependence; trait neuroticism-LPR polymorphism. A 3 · 2 ANOVA of nicotine dependence score, with genotype (L/L, L/S, S/S) and neuroticism (high

  7. Anterograde Glycoprotein-Dependent Transport of Newly Generated Rabies Virus in Dorsal Root Ganglion Neurons

    PubMed Central

    Bauer, Anja; Nolden, Tobias; Schröter, Josephine; Römer-Oberdörfer, Angela; Gluska, Shani; Perlson, Eran

    2014-01-01

    ABSTRACT Rabies virus (RABV) spread is widely accepted to occur only by retrograde axonal transport. However, examples of anterograde RABV spread in peripheral neurons such as dorsal root ganglion (DRG) neurons indicated a possible bidirectional transport by an uncharacterized mechanism. Here, we analyzed the axonal transport of fluorescence-labeled RABV in DRG neurons by live-cell microscopy. Both entry-related retrograde transport of RABV after infection at axon endings and postreplicative transport of newly formed virus were visualized in compartmentalized DRG neuron cultures. Whereas entry-related transport at 1.5 ?m/s occurred only retrogradely, after 2 days of infection, multiple particles were observed in axons moving in both the anterograde and retrograde directions. The dynamics of postreplicative retrograde transport (1.6 ?m/s) were similar to those of entry-related retrograde transport. In contrast, anterograde particle transport at 3.4 ?m/s was faster, indicating active particle transport. Interestingly, RABV missing the glycoproteins did not move anterogradely within the axon. Thus, anterograde RABV particle transport depended on the RABV glycoprotein. Moreover, colocalization of green fluorescent protein (GFP)-labeled ribonucleoproteins (RNPs) and glycoprotein in distal axonal regions as well as cotransport of labeled RNPs with membrane-anchored mCherry reporter confirmed that either complete enveloped virus particles or vesicle associated RNPs were transported. Our data show that anterograde RABV movement in peripheral DRG neurons occurs by active motor protein-dependent transport. We propose two models for postreplicative long-distance transport in peripheral neurons: either transport of complete virus particles or cotransport of RNPs and G-containing vesicles through axons to release virus at distal sites of infected DRG neurons. IMPORTANCE Rabies virus retrograde axonal transport by dynein motors supports virus spread over long distances and lethal infection of the central nervous system. Though active rabies virus transport has been widely accepted to be unidirectional, evidence for anterograde spread in peripheral neurons supports the hypothesis that in some neurons RABV also enters the anterograde pathway by so-far unknown mechanisms. By live microscopy we visualized fast anterograde axonal transport of rabies virus. The velocities exceeded those of retrograde movements, suggesting that active, most likely kinesin-dependent transport machineries are involved. Dependency of anterograde transport on the expression of virus glycoprotein G and cotransport with vesicles further suggest that complete enveloped virus particles or cotransport of virus ribonucleoprotein and G-containing vesicles occurred. These data provide the first insight in the mechanism of anterograde rabies virus transport and substantially contribute to the understanding of RABV replication and spread of newly formed virus in peripheral neurons. PMID:25275124

  8. Azimuthal anisotropy: the higher harmonics

    E-print Network

    Poskanzer, Arthur M

    2004-01-01

    We report the first observations of the fourth harmonic (v_4) in the azimuthal distribution of particles at RHIC. The measurement was done taking advantage of the large elliptic flow generated at RHIC. The integrated v_4 is about a factor of 10 smaller than v_2. For the sixth (v_6) and eighth (v_8) harmonics upper limits on the magnitudes are reported.

  9. Azimuthal anisotropy: the higher harmonics

    E-print Network

    Arthur M. Poskanzer

    2004-03-12

    We report the first observations of the fourth harmonic (v_4) in the azimuthal distribution of particles at RHIC. The measurement was done taking advantage of the large elliptic flow generated at RHIC. The integrated v_4 is about a factor of 10 smaller than v_2. For the sixth (v_6) and eighth (v_8) harmonics upper limits on the magnitudes are reported.

  10. Healthy places, active transport and path dependence: a review of the literature.

    PubMed

    Hensley, Melissa; Mateo-Babiano, Derlie; Minnery, John

    2014-12-01

    Children walking to school, people cycling to the shops or work and neighbours chatting in the street, these are some of the gauges of an active and healthy community that can be achieved through utilising good design principles. But are these principles being applied in urban developments or are policy-makers following a 'path dependent' trajectory that severely limits the best practice outcomes sought? This review examines current research on path dependence to determine how this concept advances our understanding of barriers to change in the built environment, active transport and healthy communities. An online database search of scholarly bibliographic records identified 22 relevant articles for a critical review of studies that evaluated path dependence in the urban and built environment literature with a focus on transport, urban planning and health. A thematic analysis of the articles showed that different types of path dependence have contributed to the dominance of policies and designs supporting car-based transport to the detriment of public transport and active transport modes, leading to sub-optimal development patterns becoming 'locked-in'. However, the outcomes for active transport and physical activity are not all dire, and path dependence theory does provide some guidance on changing policy to achieve better outcomes. This review suggests that path dependence is one of the best theoretical frameworks to help health promoters understand barriers to change and can provide insights into developing future successful public health interventions. Future studies could focus further on active transport, local neighbourhood development and physical activity. PMID:25481484

  11. View-dependent precomputed light transport using non-linear Gaussian function approximations

    E-print Network

    Green, Paul Elijah

    2006-01-01

    We propose a real-time method for rendering rigid objects with complex view-dependent effects under distant all-frequency lighting. Existing precomputed light transport approaches can render rich global illumination effects, ...

  12. Scale dependence of sorption coefficients for contaminant transport in saturated fractured rock

    E-print Network

    Lu, Zhiming

    Scale dependence of sorption coefficients for contaminant transport in saturated fractured rock coefficients for contaminant transport in saturated fractured rock, Geophys. Res. Lett., 36, L01403, doi:10 obtain a substantially different conceptual model than for porous media. In saturated fractured rock

  13. Spin-dependent thermoelectric transport coefficients in near perfect quantum wires A. Ramsak,1,2

    E-print Network

    Ramsak, Anton

    Spin-dependent thermoelectric transport coefficients in near perfect quantum wires T. Rejec,1 A 2002 Thermoelectric transport coefficients are determined for semiconductor quantum wires with weak in thermoelectric coefficients are also found in standard strongly correlated systems: the Anderson model,6

  14. Crystal structure of a bacterial homologue of Na+\\/Cl--dependent neurotransmitter transporters

    Microsoft Academic Search

    Atsuko Yamashita; Satinder K. Singh; Toshimitsu Kawate; Yan Jin; Eric Gouaux

    2005-01-01

    Na+\\/Cl--dependent transporters terminate synaptic transmission by using electrochemical gradients to drive the uptake of neurotransmitters, including the biogenic amines, from the synapse to the cytoplasm of neurons and glia. These transporters are the targets of therapeutic and illicit compounds, and their dysfunction has been implicated in multiple diseases of the nervous system. Here we present the crystal structure of a

  15. Modeling and analysis of time-dependent tritium transport in lithium oxide

    E-print Network

    Raffray, A. René

    the tritium transport behavior in lithium-based ceramic materials. A computer code, named MISTRAL (ModelModeling and analysis of time-dependent tritium transport in lithium oxide A. Badawi, A.R. Raray of the key factors in determining tritium self-suciency, as well as safety, of fusion reactors. Therefore

  16. Diameter Dependence of the Transport Properties of Antimony Telluride Nanowires

    E-print Network

    Heller, Eric

    hole dominant diffusive thermoelectric generation with an enhancement of the TEP for smaller diameter, Massachusetts 02138 ABSTRACT We report measurements of electronic, thermoelectric, and galvanomagnetic of 20-100 nm. Temperature-dependent resistivity and thermoelectric power (TEP) measurements indicate

  17. Composition dependence of ion-transport coefficients in gas mixtures

    NASA Technical Reports Server (NTRS)

    Whealton, J. H.; Mason, E. A.; Robson, R. E.

    1974-01-01

    Simple momentum-transfer theory for the composition dependence of ion mobilities and diffusion coefficients in gas mixtures at arbitrary field strengths is corrected and extended, and compared with a similar theory based on momentum and energy transfer, and with results based on direct solution of the Boltzmann equation by Kihara's method. Final equations are recommended for predicting composition dependences, given only results on ion mobilities and diffusion coefficients in the pure component gases.

  18. Composition dependence of ion transport coefficients in gas mixtures

    NASA Technical Reports Server (NTRS)

    Whealton, J. H.; Mason, E. A.; Robson, R. E.

    1973-01-01

    A simple momentum-transfer theory for the composition dependence of ion mobilities and diffusion coefficients in gas mixtures at arbitrary field strengths is corrected, extended, and compared with a similar theory based on momentum and energy transfer, and with results based on direct solution of the Boltzmann equation by Kihara's method. Final equations are recommended for predicting composition dependences, given only results on ion mobilities and diffusion coefficients in the pure component gases.

  19. An Additive Angular-Dependent Rebalance Acceleration Method for Neutron Transport Equations

    Microsoft Academic Search

    Nam Zin Cho; Chang Je Park

    2001-01-01

    An additive angular-dependent rebalance (AADR) factor acceleration method is described to accelerate the source iteration of discrete ordinates transport calculation. The formulation of the AADR method follows that of the angular-dependent rebalance method in that the rebalance factor is defined only on the cell interface and in that the low-order equation is derived by integrating the transport equation (high-order equation)

  20. View-dependent precomputed light transport using nonlinear Gaussian function approximations

    Microsoft Academic Search

    Paul Green; Jan Kautz; Wojciech Matusik; Frédo Durand

    2006-01-01

    We propose a real-time method for rendering rigid objects with complex view-dependent effects under distant all-frequency light- ing. Existing precomputed light transport approaches can render rich global illumination effects, but high-frequency view-dependent effects such as sharp highlights remain a challenge. We introduce a new representation of the light transport operator based on sums of Gaussians. The nonlinear parameters of our

  1. Doping Dependent Thermopower of PbTe from Boltzmann Transport

    SciTech Connect

    Singh, David J [ORNL

    2010-01-01

    The thermopower of PbTe as a function of temperature and doping level is reported based on Boltzmann transport calculations using the first principles relativistic electronic structure as obtained with the Engel-Vosko generalized gradient approximation. The results are discussed in relation to experimental data. For p-type material there is an enhancement at high-doping levels due to the onset of an increased density of states starting {approx}0.2 eV below the valence band edge. This leads to agreement between the calculated thermopower and recent results on PbTe with heavy Tl doping.

  2. Azimuthal anisotropy: The higher harmonics

    SciTech Connect

    Poskanzer, Arthur M.; STAR Collaboration

    2004-03-12

    We report the first observations of the fourth harmonic (v{sub 4}) in the azimuthal distribution of particles at RHIC. The measurement was done taking advantage of the large elliptic flow generated at RHIC. The integrated v{sub 4} is about a factor of 10 smaller than v{sub 2}. For the sixth (v{sub 6}) and eighth (v{sub 8}) harmonics upper limits on the magnitudes are reported.

  3. Scatterometer azimuthal response and wind wave directionality

    NASA Technical Reports Server (NTRS)

    Giovanangeli, J. P.; Le Calve, O.; Bliven, L.

    1989-01-01

    Azimuthal response of a scatterometer to radiation scattered by the sea surface was studied in a wind-wave tank. The variation of the normalized radar cross section with the azimuth angle is fitted by a three-term series. Results show that the upwind-downwind asymmetry decreases as the wind speed increases. The crosswind modulation depends on the wind velocity. The results show that the evolution of the long-wind-crosswind ratio evolves with wind speed in a manner similar to the evolution of the isotropy of short capillary-gravity waves. The maximum of the isotropy of the short wind waves is obtained for wind velocities close to 4 m/s. For the same value of the velocity, the variations of radar response between long-wind and crosswind directions is minimum. For lower or higher values of wind velocities the directional accuracy of the radar increases, since the wind-wave field tends to align in the wind direction.

  4. Structural insights into substrate recognition in proton-dependent oligopeptide transporters

    PubMed Central

    Guettou, Fatma; Quistgaard, Esben M; Trésaugues, Lionel; Moberg, Per; Jegerschöld, Caroline; Zhu, Lin; Jong, Agnes Jin Oi; Nordlund, Pär; Löw, Christian

    2013-01-01

    Short-chain peptides are transported across membranes through promiscuous proton-dependent oligopeptide transporters (POTs)—a subfamily of the major facilitator superfamily (MFS). The human POTs, PEPT1 and PEPT2, are also involved in the absorption of various drugs in the gut as well as transport to target cells. Here, we present a structure of an oligomeric POT transporter from Shewanella oneidensis (PepTSo2), which was crystallized in the inward open conformation in complex with the peptidomimetic alafosfalin. All ligand-binding residues are highly conserved and the structural insights presented here are therefore likely to also apply to human POTs. PMID:23867627

  5. Fast axonal transport of the proteasome complex depends on membrane interaction and molecular motor function.

    PubMed

    Otero, Maria G; Alloatti, Matías; Cromberg, Lucas E; Almenar-Queralt, Angels; Encalada, Sandra E; Pozo Devoto, Victorio M; Bruno, Luciana; Goldstein, Lawrence S B; Falzone, Tomás L

    2014-04-01

    Protein degradation by the ubiquitin-proteasome system in neurons depends on the correct delivery of the proteasome complex. In neurodegenerative diseases, aggregation and accumulation of proteins in axons link transport defects with degradation impairments; however, the transport properties of proteasomes remain unknown. Here, using in vivo experiments, we reveal the fast anterograde transport of assembled and functional 26S proteasome complexes. A high-resolution tracking system to follow fluorescent proteasomes revealed three types of motion: actively driven proteasome axonal transport, diffusive behavior in a viscoelastic axonema and proteasome-confined motion. We show that active proteasome transport depends on motor function because knockdown of the KIF5B motor subunit resulted in impairment of the anterograde proteasome flux and the density of segmental velocities. Finally, we reveal that neuronal proteasomes interact with intracellular membranes and identify the coordinated transport of fluorescent proteasomes with synaptic precursor vesicles, Golgi-derived vesicles, lysosomes and mitochondria. Taken together, our results reveal fast axonal transport as a new mechanism of proteasome delivery that depends on membrane cargo 'hitch-hiking' and the function of molecular motors. We further hypothesize that defects in proteasome transport could promote abnormal protein clearance in neurodegenerative diseases. PMID:24522182

  6. The renal transport of taurine and the regulation of renal sodium-chloride-dependent transporter activity

    Microsoft Academic Search

    Russell W. Chesney; Israel Zelikovic; Deborah P. Jones; Andrea Budreau; Kent Jolly

    1990-01-01

    A model for the ß-amino acid taurine transport is presented to help define the ionic, pH, and voltage requirements for the movement of taurine into the rat proximal tubule brush border membrane vesicle (BBMV). Sodium-(Na+)-taurine symport across the apical surface of the proximal tubule has a highly specific requirement for Cl- and Br-. Active taurine transport operates with a 2

  7. Theory of spin-dependent transport in ferromagnet-semiconductor heterostructures

    Microsoft Academic Search

    Mark Johnson

    1998-01-01

    The formalism of spin-dependent transport is used to calculate the conductance of device structures comprised of a two-dimensional electron-gas (2DEG) channel and ferromagnetic source and\\/or drain for a variety of magnetization configurations. Among the effects predicted by the calculations is spin-dependent current rectification at a 2DEG-ferromagnet interface.

  8. Time-dependent electron transport through an Aharonov–Bohm ring embedded with two quantum dots

    Microsoft Academic Search

    Hui Pan; Li-Na Zhao; Rong Lü

    2008-01-01

    The time-dependent electron transport through an Aharonov–Bohm ring embedded with two quantum dots in the presence of external microwave (MW) fields are investigated theoretically by using the nonequilibrium Green's function method. Whether the MW field can induce or suppress the Fano resonance depends on the part to which the field is applied. When the MW field is applied only to

  9. Temperature-Dependent Transport in Suspended Graphene K. I. Bolotin,1

    E-print Network

    Kim, Philip

    Temperature-Dependent Transport in Suspended Graphene K. I. Bolotin,1 K. J. Sikes,2 J. Hone,3 H. L of ultraclean suspended graphene is strongly temperature (T) dependent for 5 carrier scattering from acoustic phonons. At T 240 K the mobility is 120 000 cm2 =V s, higher than in any

  10. Kinetic Approach to Quasi-Ballistic Field-Dependent Electron Transport

    E-print Network

    Pulfrey, David L.

    Kinetic Approach to Quasi-Ballistic Field-Dependent Electron Transport A. R. St.Denis1 and D. L, the components of the two fluxes are not as easily described. Here we visualize the various components (ballistic of the different ways a carrier can come to be at #12;Kinetic Approach to Quasi-Ballistic Field-Dependent Electron

  11. Asymptotic analysis of the several competitive equations to solve the time-dependent neutron transport equation

    SciTech Connect

    Shin, U.; Miller, W.F. Jr. [California Univ., Berkeley, CA (United States)]|[Los Alamos National Lab., NM (United States); Morel, J.E. [Los Alamos National Lab., NM (United States)

    1994-10-01

    Using conventional diffusion limit analysis, we asymptotically compare three competitive time-dependent equations (the telegrapher`s equation, the time-dependent Simplified P{sub 2} (SP{sub 2}) equation, and the time-dependent Simplified Evcn-Parity (SEP) equation). The time-dependent SP{sub 2} equation contains higher order asymptotic approximations of the time-dependent transport equation than the other equations in a physical regime in which the time-dependent diffusion equation is the leading order approximation. In addition, we derive the multigroup modified time-dependent SP{sub 2} equation from the multigroup time-dependent transport equation by means of an asymptotic expansion in which the multigroup time-dependent diffusion equation is the leading, order approximation. Numerical comparisons of the timedependent diffusion, the telegrapher`s, the time-dependent SP{sub 2}, and S{sub 8} solutions in 2-D X-Y geometry show that, in most cases, the SP{sub 2} solutions contain most of the transport corrections for the diffusion approximation.

  12. Diameter dependence of the transport properties of antimony telluride nanowires.

    PubMed

    Zuev, Yuri M; Lee, Jin Seok; Galloy, Clément; Park, Hongkun; Kim, Philip

    2010-08-11

    We report measurements of electronic, thermoelectric, and galvanomagnetic properties of individual single crystal antimony telluride (Sb(2)Te(3)) nanowires with diameters in the range of 20-100 nm. Temperature-dependent resistivity and thermoelectric power (TEP) measurements indicate hole dominant diffusive thermoelectric generation with an enhancement of the TEP for smaller diameter wires up to 110 microV/K at T = 300 K. We measure the magnetoresistance in magnetic fields both parallel and perpendicular to the nanowire [110] axis, where strong anisotropic positive magnetoresistance behavior was observed. PMID:20698617

  13. Deterministic methods for time-dependent stochastic neutron transport

    SciTech Connect

    Baker, Randal S [Los Alamos National Laboratory

    2009-01-01

    A numerical method is presented for solving the time-dependent survival probability equation in general (lD/2D/3D) geometries using the multi group SNmethod. Although this equation was first formulated by Bell in the early 1960's, it has only been applied to stationary systems (for other than idealized point models) until recently, and detailed descriptions of numerical solution techniques are lacking in the literature. This paper presents such a description and applies it to a dynamic system representative of a figurative criticality accident scenario.

  14. Strain dependence of the heat transport properties of graphene nanoribbons.

    PubMed

    Yeo, Pei Shan Emmeline; Loh, Kian Ping; Gan, Chee Kwan

    2012-12-14

    Using a combination of accurate density-functional theory and a nonequilibrium Green's function method, we calculate the ballistic thermal conductance characteristics of tensile-strained armchair (AGNR) and zigzag (ZGNR) edge graphene nanoribbons, with widths between 3 and 50 ?. The optimized lateral lattice constants for AGNRs of different widths display a three-family behavior when the ribbons are grouped according to N modulo 3, where N represents the number of carbon atoms across the width of the ribbon. Two lowest-frequency out-of-plane acoustic modes play a decisive role in increasing the thermal conductance of AGNR-N at low temperatures. At high temperatures the effect of tensile strain is to reduce the thermal conductance of AGNR-N and ZGNR-N. These results could be explained by the changes in force constants in the in-plane and out-of-plane directions with the application of strain. This fundamental atomistic understanding of the heat transport in graphene nanoribbons paves a way to effect changes in their thermal properties via strain at various temperatures. PMID:23149343

  15. A NEW MONTE CARLO METHOD FOR TIME-DEPENDENT NEUTRINO RADIATION TRANSPORT

    SciTech Connect

    Abdikamalov, Ernazar; Ott, Christian D.; O'Connor, Evan [TAPIR, California Institute of Technology, MC 350-17, 1200 E California Blvd., Pasadena, CA 91125 (United States); Burrows, Adam; Dolence, Joshua C. [Department of Astrophysical Sciences, Princeton University, Peyton Hall, Ivy Lane, Princeton, NJ 08544 (United States); Loeffler, Frank; Schnetter, Erik, E-mail: abdik@tapir.caltech.edu [Center for Computation and Technology, Louisiana State University, 216 Johnston Hall, Baton Rouge, LA 70803 (United States)

    2012-08-20

    Monte Carlo approaches to radiation transport have several attractive properties such as simplicity of implementation, high accuracy, and good parallel scaling. Moreover, Monte Carlo methods can handle complicated geometries and are relatively easy to extend to multiple spatial dimensions, which makes them potentially interesting in modeling complex multi-dimensional astrophysical phenomena such as core-collapse supernovae. The aim of this paper is to explore Monte Carlo methods for modeling neutrino transport in core-collapse supernovae. We generalize the Implicit Monte Carlo photon transport scheme of Fleck and Cummings and gray discrete-diffusion scheme of Densmore et al. to energy-, time-, and velocity-dependent neutrino transport. Using our 1D spherically-symmetric implementation, we show that, similar to the photon transport case, the implicit scheme enables significantly larger timesteps compared with explicit time discretization, without sacrificing accuracy, while the discrete-diffusion method leads to significant speed-ups at high optical depth. Our results suggest that a combination of spectral, velocity-dependent, Implicit Monte Carlo and discrete-diffusion Monte Carlo methods represents a robust approach for use in neutrino transport calculations in core-collapse supernovae. Our velocity-dependent scheme can easily be adapted to photon transport.

  16. A New Monte Carlo Method for Time-dependent Neutrino Radiation Transport

    NASA Astrophysics Data System (ADS)

    Abdikamalov, Ernazar; Burrows, Adam; Ott, Christian D.; Löffler, Frank; O'Connor, Evan; Dolence, Joshua C.; Schnetter, Erik

    2012-08-01

    Monte Carlo approaches to radiation transport have several attractive properties such as simplicity of implementation, high accuracy, and good parallel scaling. Moreover, Monte Carlo methods can handle complicated geometries and are relatively easy to extend to multiple spatial dimensions, which makes them potentially interesting in modeling complex multi-dimensional astrophysical phenomena such as core-collapse supernovae. The aim of this paper is to explore Monte Carlo methods for modeling neutrino transport in core-collapse supernovae. We generalize the Implicit Monte Carlo photon transport scheme of Fleck & Cummings and gray discrete-diffusion scheme of Densmore et al. to energy-, time-, and velocity-dependent neutrino transport. Using our 1D spherically-symmetric implementation, we show that, similar to the photon transport case, the implicit scheme enables significantly larger timesteps compared with explicit time discretization, without sacrificing accuracy, while the discrete-diffusion method leads to significant speed-ups at high optical depth. Our results suggest that a combination of spectral, velocity-dependent, Implicit Monte Carlo and discrete-diffusion Monte Carlo methods represents a robust approach for use in neutrino transport calculations in core-collapse supernovae. Our velocity-dependent scheme can easily be adapted to photon transport.

  17. Incoherent Interlayer Transport and Angular-Dependent Magnetoresistance Oscillations in Layered Metals

    Microsoft Academic Search

    Ross H. McKenzie; Perez Moses

    1998-01-01

    The effect of incoherent interlayer transport on the interlayer resistance of a layered metal is considered. We find that for both quasi-one-dimensional and quasi-two-dimensional Fermi liquids the angular dependence of the magnetoresistance is essentially the same for coherent and incoherent transport. Consequently, the existence of a three-dimensional Fermi surface is not necessary to explain the oscillations in the magnetoresistance that

  18. A method for inversion of layered shear wavespeed azimuthal anisotropy from Rayleigh wave dispersion using the Neighborhood Algorithm

    NASA Astrophysics Data System (ADS)

    Yao, Huajian

    2015-02-01

    Seismic anisotropy provides important constraints on deformation patterns of Earth's material. Rayleigh wave dispersion data with azimuthal anisotropy can be used to invert for depth-dependent shear wavespeed azimuthal anisotropy, therefore reflecting depth-varying deformation patterns in the crust and upper mantle. In this study, we propose a two-step method that uses the Neighborhood Algorithm (NA) for the point-wise inversion of depth-dependent shear wavespeeds and azimuthal anisotropy from Rayleigh wave azimuthally anisotropic dispersion data. The first step employs the NA to estimate depth-dependent V SV (or the elastic parameter L) as well as their uncertainties from the isotropic part Rayleigh wave dispersion data. In the second step, we first adopt a difference scheme to compute approximate Rayleigh-wave phase velocity sensitivity kernels to azimuthally anisotropic parameters with respect to the velocity model obtained in the first step. Then we perform the NA to estimate the azimuthally anisotropic parameters G c/ L and G s/ L at depths separately from the corresponding cosine and sine terms of the azimuthally anisotropic dispersion data. Finally, we compute the depth-dependent magnitude and fast polarization azimuth of shear wavespeed azimuthal anisotropy. The use of the global search NA and Bayesian analysis allows for more reliable estimates of depth-dependent shear wavespeeds and azimuthal anisotropy as well as their uncertainties. We illustrate the inversion method using the azimuthally anisotropic dispersion data in SE Tibet, where we find apparent changes of fast axes of shear wavespeed azimuthal anisotropy between the crust and uppermost mantle.

  19. JSAP1/JIP3 and JLP regulate kinesin-1-dependent axonal transport to prevent neuronal degeneration.

    PubMed

    Sato, T; Ishikawa, M; Mochizuki, M; Ohta, M; Ohkura, M; Nakai, J; Takamatsu, N; Yoshioka, K

    2015-08-01

    Axonal transport is critical for neuronal development and function, and defective axonal transport has been implicated in neurodegenerative diseases. However, how axonal transport is regulated, or how defective transport leads to neuronal degeneration, remains unclear. Here, we report that c-Jun NH2-terminal kinase (JNK)/stress-activated protein kinase-associated protein 1 (JSAP1, also known as JNK-interacting protein 3 (JIP3)) and JNK-associated leucine zipper protein (JLP) are essential for postnatal brain development. Mice with a double-knockout (dKO) in Jsap1 and Jlp in the dorsal telencephalon developed progressive neuron loss. Using a primary neuron culture system with induced disruption of targeted genes, combined with gene rescue experiments, we show that JSAP1 and JLP regulate kinesin-1-dependent axonal transport with functional redundancy. We also show that the binding of JSAP1 and JLP to kinesin-1 heavy chain is crucial for interactions between kinesin-1 and microtubules. Furthermore, we describe a molecular mechanism by which defective kinesin-1-dependent axonal transport in Jsap1:Jlp dKO neurons causes axonal degeneration and subsequent neuronal death. JNK hyperactivation because of increased intra-axonal Ca(2+) in the Jsap1:Jlp dKO neurons was found to mediate both the axonal degeneration and neuronal death, in cooperation with the Ca(2+)-dependent protease calpain. Our results indicate that axonal JNK may relocate to the nucleus in a dynein-dependent manner, where it activates the transcription factor c-Jun, resulting in neuronal death. Taken together, our data establish JSAP1 and JLP as positive regulators of kinesin-1-dependent axonal transport, which prevents neuronal degeneration. PMID:25571974

  20. High specificity in response of the sodium-dependent multivitamin transporter to derivatives of pantothenic acid.

    PubMed

    Chirapu, Srinivas Reddy; Rotter, Charles J; Miller, Emily L; Varma, Manthena V; Dow, Robert L; Finn, M G

    2013-01-01

    Essential nutrients are attractive targets for the transport of biologically active agents across cell membranes, since many are substrates for active cellular importation pathways. The sodium-dependent multivitamin transporter (SMVT) is among the best characterized of these, and biotin derivatives have been its most popular targets. We have surveyed 45 derivatives of pantothenic acid, another substrate of SMVT, long known as a competitive inhibitor of biotin transport. Variations of the ?-alanyl fragment of pantothenate were uniformly rejected by the transporter, including derivatives with very similar steric and acidic characteristics to the natural substrate. The secondary hydroxyl of the 2,2-dimethyl-1,3-propanediol (pantoyl) fragment was the only position at which potential linkers could be attached while retaining activity as an inhibitor of biotin uptake and a substrate for sodium-dependent transport. However, triazole conjugates to several drug-like cargo motifs were not accepted as substrates by human SMVT in cell culture. Two compounds were observed which did not inhibit biotin uptake but were themselves transported in a sodium-dependent fashion, suggesting more complex behavior than expected. These studies represent the most extensive examination to date of pantothenate as an anchor for SMVT-mediated drug delivery, showing that this route requires further investigation before being judged promising. PMID:23578027

  1. An improved azimuthal estimator for conventional SSR

    Microsoft Academic Search

    G. Galati; F. A. Studer

    1987-01-01

    Azimuth estimators based on target 'begin' and 'end' are primarily conceived for the purposes of detection: the azimuth estimate is a side-product. Attention is presently given to an improved estimator based on the maximum likelihood estimator approach, which is especially suited to such specific azimuth estimation problems as missed replies and which takes advantage of the high S\\/N and steady-target

  2. A transition in mechanisms of size dependent electrical transport at nanoscale metal-oxide interfaces

    SciTech Connect

    Hou, Jiechang; Nonnenmann, Stephen S.; Qin, Wei; Bonnell, Dawn A., E-mail: bonnell@lrsm.seas.upenn.edu [Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104 (United States)

    2013-12-16

    As device miniaturization approaches nanoscale dimensions, interfaces begin to dominate electrical properties. Here the system archetype Au/SrTiO{sub 3} is used to examine the origin of size dependent transport properties along metal-oxide interfaces. We demonstrate that a transition between two classes of size dependent electronic transport mechanisms exists, defined by a critical size ?. At sizes larger than ? an edge-related tunneling effect proportional to 1/D (the height of the supported Au nanoparticle) is observed; interfaces with sizes smaller than ? exhibit random fluctuations in current. The ability to distinguish between these mechanisms is important to future developments in nanoscale device design.

  3. Receptor-Dependent and -Independent Axonal Retrograde Transport of Poliovirus in Motor Neurons? †

    PubMed Central

    Ohka, Seii; Sakai, Mai; Bohnert, Stephanie; Igarashi, Hiroko; Deinhardt, Katrin; Schiavo, Giampietro; Nomoto, Akio

    2009-01-01

    Poliovirus (PV), when injected intramuscularly into the calf, is incorporated into the sciatic nerve and causes an initial paralysis of the inoculated limb in transgenic (Tg) mice carrying the human PV receptor (hPVR/CD155) gene. We have previously demonstrated that a fast retrograde axonal transport process is required for PV dissemination through the sciatic nerves of hPVR-Tg mice and that intramuscularly inoculated PV causes paralytic disease in an hPVR-dependent manner. Here we showed that hPVR-independent axonal transport of PV was observed in hPVR-Tg and non-Tg mice, indicating that several different pathways for PV axonal transport exist in these mice. Using primary motor neurons (MNs) isolated from these mice or rats, we demonstrated that the axonal transport of PV requires several kinetically different motor machineries and that fast transport relies on a system involving cytoplasmic dynein. Unexpectedly, the hPVR-independent axonal transport of PV was not observed in cultured MNs. Thus, PV transport machineries in cultured MNs and in vivo differ in their hPVR requirements. These results suggest that the axonal trafficking of PV is carried out by several distinct pathways and that MNs in culture and in the sciatic nerve in situ are intrinsically different in the uptake and axonal transport of PV. PMID:19244317

  4. Temperature dependent electrical transport behavior of InN/GaN heterostructure based Schottky diodes

    SciTech Connect

    Roul, Basanta; Kumar, Mahesh [Materials Research Centre, Indian Institute of Science, Bangalore 560012 (India); Central Research Laboratory, Bharat Electronics, Bangalore 560013 (India); Rajpalke, Mohana K.; Bhat, Thirumaleshwara N.; Krupanidhi, S. B. [Materials Research Centre, Indian Institute of Science, Bangalore 560012 (India); Sinha, Neeraj [Office of Principal Scientific Advisor, Government of India, New Delhi 110011 (India); Kalghatgi, A. T. [Central Research Laboratory, Bharat Electronics, Bangalore 560013 (India)

    2011-02-15

    InN/GaN heterostructure based Schottky diodes were fabricated by plasma-assisted molecular beam epitaxy. The temperature dependent electrical transport properties were carried out for InN/GaN heterostructure. The barrier height and the ideality factor of the Schottky diodes were found to be temperature dependent. The temperature dependence of the barrier height indicates that the Schottky barrier height is inhomogeneous in nature at the heterostructure interface. The higher value of the ideality factor and its temperature dependence suggest that the current transport is primarily dominated by thermionic field emission (TFE) other than thermionic emission (TE). The room temperature barrier height obtained by using TE and TFE models were 1.08 and 1.43 eV, respectively.

  5. Effect of ischemia reperfusion on sodium-dependent phosphate transport in renal brush border membranes.

    PubMed

    Khundmiri, Syed J; Asghar, Mohammed; Banday, Anees A; Khan, Farah; Salim, Samina; Levi, Moshe; Yusufi, Ahad N K

    2005-10-01

    The effect of ischemia induced acute renal failure (ARF) on the transport of phosphate (Pi) after early (15-30 min) and prolonged (60 min) ischemia in the brush border membrane vesicles (BBMV) from rat renal cortex was studied. Sodium-dependent transport of Pi declined significantly and progressively due to ischemia. Western blot analysis of BBM from ischemic rats showed decreased expression of NaPi-2. A compensatory increase was observed in Pi uptake in BBMV from contralateral kidneys. There was no significant difference in NaPi-2 expression between BBMV from sham and contralateral kidneys. Early blood reperfusion for 15 min after 30 min ischemia caused further decline in Pi uptake. Prolonged reperfusion for 120 min caused partial reversal of transport activities in 30-min ischemic rats. However, no improvement in the transport of Pi was observed in 60-min ischemic rats after 120 min of blood reperfusion. Kinetic studies showed that the effect of ischemia and blood reperfusion was dependent on the Vmax of the Na-Pi transporter. Western blot analysis showed increased expression of NaPi-2 in the BBMs from ischemia-reperfusion animals. Further, a shift in the association of Na ions to transport one molecule of Pi was observed under different extracellular Na concentrations [Na]o. Feeding rats with low Pi diet and/or treatment with thyroid hormone (T3) prior to ischemia resulted in increased basal Pi transport. Ischemia caused similar decline in Pi transport in BBM from LPD and/or T3 animals. However, recovery in these animals was faster than the normal Pi diet fed (NPD) animals. The study suggests a change in the intrinsic properties of the Na-Pi transporter in rat kidneys due to ischemia. The study also indicates that treatment with T3 and feeding LPD prior to ischemia caused faster recovery of phosphate uptake due to ischemia-reperfusion injury. PMID:16182235

  6. A cylinder-to-sphere Fourier view factor model for azimuthal asymmetry studies in cylindrical hohlraums

    NASA Astrophysics Data System (ADS)

    Giorla, J.; Poggi, F.; Paillard, D.

    2002-01-01

    This work addresses the analytical calculation of the irradiation coming from a cylindrical surface to a spherical one. This exact solution of the x-ray transport equation allows one to connect the emitted and the received fluxes, expanded as Fourier modes, by coefficients called Fourier view factors. Such a calculation is well suited to a symmetry study in the Laser Megajoule configuration [P.-A. Holstein, M. André, M. Casanova et al., C. R. Acad. Sci. Paris 1, 693 (2000)] where a cylindrical hohlraum and a spherical capsule are irradiated. Indeed, this 60 quad laser system induces an azimuthal asymmetry of the hohlraum lighting depending on the laser focal spot size. Thus, the Fourier view factors allow one to express the modes of the capsule irradiation as functions of the elliptic spot dimensions.

  7. Interacting effects of the serotonin transporter gene and neuroticism in smoking practices and nicotine dependence

    Microsoft Academic Search

    C Lerman; N E Caporaso; J Audrain; D Main; N R Boyd; P G Shields

    2000-01-01

    Individual differences in propensity to nicotine dependence appear to be mediated, in part, by genetic factors.1 The serotonin transporter gene has a functional polymorphism (5-HTTLPR) which modulates gene transcription and reuptake.2, 3 A possible role in nicotine dependence is suggested by a link between 5-HTTLPR and neuroticism,4 a personality trait which has been related to smoking practices.5 In a cross-sectional

  8. Dependence on Initial Conditions, Memory Efiects, and Ergodicity of Transport in Heterogeneous Media

    Microsoft Academic Search

    N. Suciu; C. Vamo; H. Vereecken; K. Sabelfeld; P. Knabner

    Memory efiects in the pre-asymptotic regime of transport in heterogeneous media, indicated by reliable numerical experiments, are explained by a dependence on initial conditions which is speciflc for systems with space variable properties such as aquifers, turbulent atmosphere or ionized plasmas. For statistically homogeneous random velocity flelds, with flnite correlation range, incompressible, and continuously difierentiable, the one-particle dispersion (average over

  9. Continuous Energy, Multi-Dimensional Transport Calculations for Problem Dependent Resonance Self-Shielding

    SciTech Connect

    T. Downar

    2009-03-31

    The overall objective of the work here has been to eliminate the approximations used in current resonance treatments by developing continuous energy multi-dimensional transport calculations for problem dependent self-shielding calculations. The work here builds on the existing resonance treatment capabilities in the ORNL SCALE code system.

  10. Time-dependent radiation transport in a one-dimensional medium

    NASA Technical Reports Server (NTRS)

    Nagel, W.; Meszaros, P.

    1985-01-01

    An analytic solution of the time-dependent radiation transport problem in a one-dimensional, stationary and homogeneous medium of finite thickness is presented. The solution is found by the method of images, and is compared with an eigenfunction expansion. Previous conjectures about the structure of such an expansion are clarified. The Green's function of this problem is also expanded in scattering orders.

  11. Functional Expression of Sodium-Dependent Vitamin C Transporter 2 in Human Endothelial Cells

    Microsoft Academic Search

    Tadashi Seno; Nobutaka Inoue; Kiyoko Matsui; Junya Ejiri; Ken-ichi Hirata; Seinosuke Kawashima; Mitsuhiro Yokoyama

    2004-01-01

    Since oxidative stress plays an important role in dysregulation of the microcirculation as well as the pathogenesis of atherosclersosis, therapeutic intervention with antioxidants has been speculated to prevent cardiovascular diseases. Ascorbic acid (AA) has been reported to improve endothelial function; however, its intracellular metabolic pathway has not been fully determined. Sodium-dependent vitamin C transporter (SVCT) types 1 and 2 were

  12. Numerical Study of Electromagnetic ETG Turbulence: -dependence of Electron Heat Transport

    E-print Network

    , which describes the evolution of three macroscopic fields: the electrostatic potential, the vectorNumerical Study of Electromagnetic ETG Turbulence: -dependence of Electron Heat Transport B. Labit potential and the electron pressure. There is some evidence from experiments on Tore Supra tokamak

  13. Alcohol and the calcium-dependent potassium transport of human erythrocytes

    Microsoft Academic Search

    R. A. Harris; K. K. Caldwell

    1985-01-01

    In vitro exposure of human red blood cells to ethanol (100 and 400 mM) was found to increase the initial rate of calcium-dependent potassium efflux through the red cell membrane. This effect of ethanol was apparently not due to an elevation of the intracellular free calcium but rather to a direct action of the drug on the transport process as,

  14. Coherent Transport of Neutral Atoms in Spin-Dependent Optical Lattice Potentials

    Microsoft Academic Search

    Olaf Mandel; Markus Greiner; Artur Widera; Tim Rom; Theodor W. Hänsch; Immanuel Bloch

    2003-01-01

    We demonstrate the controlled coherent transport and splitting of atomic wave packets in spin-dependent optical lattice potentials. Such experiments open intriguing possibilities for quantum state engineering of many body states. After first preparing localized atomic wave functions in an optical lattice through a Mott insulating phase, we place each atom in a superposition of two internal spin states. Then state

  15. Measurements of Unpolarized Azimuthal Asymmetries at COMPASS

    E-print Network

    W. Käfer; for the COMPASS collaboration

    2008-08-01

    Azimuthal Asymmetries in unpolarized SIDIS can be used to probe the transverse momentum of quarks inside the nucleon. Furthermore, they give access to the so-far unmeasured Boer-Mulders function. We report on the first measurement of azimuthal asymmetries of the SIDIS cross section from scattering of muons off a deuteron target.

  16. An asymptotic-preserving Lagrangian algorithm for the time-dependent anisotropic heat transport equation

    SciTech Connect

    Chacon, Luis [Los Alamos National Laboratory (LANL), Los Alamos, NM (United States); del-Castillo-Negrete, Diego [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States); Hauck, Cory D. [Univ. of Tennessee, Knoxville, TN (United States)

    2014-09-01

    We propose a Lagrangian numerical algorithm for a time-dependent, anisotropic temperature transport equation in magnetized plasmas in the large guide field regime. The approach is based on an analytical integral formal solution of the parallel (i.e., along the magnetic field) transport equation with sources, and it is able to accommodate both local and non-local parallel heat flux closures. The numerical implementation is based on an operator-split formulation, with two straightforward steps: a perpendicular transport step (including sources), and a Lagrangian (field-line integral) parallel transport step. Algorithmically, the first step is amenable to the use of modern iterative methods, while the second step has a fixed cost per degree of freedom (and is therefore scalable). Accuracy-wise, the approach is free from the numerical pollution introduced by the discrete parallel transport term when the perpendicular to parallel transport coefficient ratio X? /X? becomes arbitrarily small, and is shown to capture the correct limiting solution when ? = X?L2?/X1L2? ? 0 (with L?? L? , the parallel and perpendicular diffusion length scales, respectively). Therefore, the approach is asymptotic-preserving. We demonstrate the capabilities of the scheme with several numerical experiments with varying magnetic field complexity in two dimensions, including the case of transport across a magnetic island.

  17. HST observations of azimuthal asymmetry in Saturn's rings

    Microsoft Academic Search

    Richard G. French; Heikki Salo; Colleen A. McGhee; Luke Dones

    2007-01-01

    From 378 Hubble Space Telescope WFPC2 images obtained between 1996–2004, we have measured the detailed nature of azimuthal brightness variations in Saturn's rings. The extensive geometric coverage, high spatial resolution (?300 kmpx?1), and photometric precision of the UBVRI images have enabled us to determine the dependence of the asymmetry amplitude and longitude of minimum brightness on orbital radius, ring elevation, wavelength,

  18. Azimuthal spin asymmetries in light-cone constituent quark models

    SciTech Connect

    Boffi, S.; Pasquini, B. [Dipartimento di Fisica Nucleare e Teorica, Universita degli Studi di Pavia, Pavia (Italy); Istituto Nazionale di Fisica Nucleare, Sezione di Pavia, Pavia (Italy); Efremov, A. V. [Joint Institute for Nuclear Research, Dubna, 141980 (Russian Federation); Schweitzer, P. [Department of Physics, University of Connecticut, Storrs, Connecticut 06269 (United States)

    2009-05-01

    We present results for all leading-twist azimuthal spin asymmetries in semi-inclusive lepton-nucleon deep-inelastic scattering due to T-even transverse-momentum dependent parton distribution functions on the basis of a light-cone constituent quark model. Attention is paid to discuss the range of applicability of the model, especially with regard to the scale dependence of the observables and the transverse-momentum dependence of the distributions. We find good agreement with available experimental data and present predictions to be further tested by future CLAS, COMPASS, and HERMES data.

  19. Electroosmotic transport in polyelectrolyte-grafted nanochannels with pH-dependent charge density

    NASA Astrophysics Data System (ADS)

    Chen, Guang; Das, Siddhartha

    2015-05-01

    "Smart" polyelectrolyte-grafted or "soft" nanochannels with pH-responsiveness have shown great promise for applications like manipulation of ion transport, ion sensing and selection, current rectification, and many more. In this paper, we develop a theory to study the electroosmotic transport in a polyelectrolyte-grafted (or soft) nanochannel with pH-dependent charge density. In one of our recent studies, we have identified that explicit consideration of hydrogen ion concentration is mandatory for appropriately describing the electrostatics of such systems and the resulting monomer concentration must obey a non-unique, cubic distribution. Here, we use this electrostatic calculation to study the corresponding electroosmotic transport. We establish that the effect of pH in the electroosmotic transport in polyelectrolyte-grafted nanochannels introduces two separate issues: first is the consideration of the hydrogen and hydroxyl ion concentrations in describing the electroosmotic body force, and second is the consideration of the appropriate drag force that bears the signature of this cubic monomeric distribution. Our results indicate that the strength of the electroosmotic velocity for the pH-dependent case is always smaller than that for the pH-independent case, with the extent of this difference being a function of the system parameters. Such nature of the electroosmotic transport will be extremely significant in suppressing the electroosmotic flow strength with implications in large number applications such as capillary electrophoresis induced separation, electric field mediated DNA elongation, electrophoretic DNA nanopore sequencing, and many more.

  20. Transport by Populations of Fast and Slow Kinesins Uncovers Novel Family-Dependent Motor Characteristics Important for In Vivo Function

    E-print Network

    Hancock, William O.

    kinesins include melanosomes (1), intraflagellar transport particles (2­4), axonal transport vesicles (5Article Transport by Populations of Fast and Slow Kinesins Uncovers Novel Family-Dependent Motor made in characterizing kinesin motors at the single-molecule level, predicting their ensemble behavior

  1. Nonmonotonic temperature dependent transport in graphene grown by chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Heo, J.; Chung, H. J.; Lee, Sung-Hoon; Yang, H.; Seo, D. H.; Shin, J. K.; Chung, U.-In; Seo, S.; Hwang, E. H.; Das Sarma, S.

    2011-07-01

    Carrier density and temperature-dependent resistivity of graphene grown by chemical vapor deposition (CVD) is investigated. We observe in low mobility CVD graphene device a generic insulating behavior at low temperatures, and eventually a metallic behavior at high temperatures, manifesting a nonmonotonic temperature dependent resistivity. This feature is strongly affected by carrier density modulation with the low-density samples exhibiting insulating-like temperature dependence up to higher temperatures than the corresponding high-density samples. To explain the temperature and density dependence of the resistivity, we introduce thermal activation of charge carriers in electron-hole puddles induced by randomly distributed charged impurities. Our observed temperature evolution of resistivity is then understood from the competition among thermal activation of charge carriers, temperature-dependent screening, and phonon scattering effects. Our experimental results are in good agreement with recent theories of graphene transport.

  2. Sodium dependent multivitamin transporter (SMVT): a potential target for drug delivery.

    PubMed

    Vadlapudi, Aswani Dutt; Vadlapatla, Ramya Krishna; Mitra, Ashim K

    2012-06-01

    Sodium dependent multivitamin transporter (SMVT; product of the SLC5A6 gene) is an important transmembrane protein responsible for translocation of vitamins and other essential cofactors such as biotin, pantothenic acid and lipoic acid. Hydropathy plot (Kyte-Dolittle algorithm) revealed that human SMVT protein consists of 635 amino acids and 12 transmembrane domains with both amino and carboxyl termini oriented towards the cytoplasm. SMVT is expressed in various tissues such as placenta, intestine, brain, liver, lung, kidney, cornea, retina and heart. This transporter displays broad substrate specificity and excellent capacity for utilization in drug delivery. Drug absorption is often limited by the presence of physiological (epithelial tight junctions), biochemical (efflux transporters and enzymatic degradation) and chemical (size, lipophilicity, molecular weight, charge etc.) barriers. These barriers may cause many potential therapeutics to be dropped from the preliminary screening portfolio and subsequent entry into the market. Transporter targeted delivery has become a powerful approach to deliver drugs to target tissues because of the ability of the transporter to translocate the drug to intracellular organelles at a higher rate. This review highlights studies employing SMVT transporter as a target for drug delivery to improve bioavailability and investigate the feasibility of developing SMVT targeted drug delivery systems. PMID:22420308

  3. Sodium Dependent Multivitamin Transporter (SMVT): A Potential Target for Drug Delivery

    PubMed Central

    Vadlapudi, Aswani Dutt; Vadlapatla, Ramya Krishna; Mitra, Ashim K.

    2015-01-01

    Sodium dependent multivitamin transporter (SMVT; product of the SLC5A6 gene) is an important transmembrane protein responsible for translocation of vitamins and other essential cofactors such as biotin, pantothenic acid and lipoic acid. Hydropathy plot (Kyte-Dolittle algorithm) revealed that human SMVT protein consists of 635 amino acids and 12 transmembrane domains with both amino and carboxyl termini oriented towards the cytoplasm. SMVT is expressed in various tissues such as placenta, intestine, brain, liver, lung, kidney, cornea, retina and heart. This transporter displays broad substrate specificity and excellent capacity for utilization in drug delivery. Drug absorption is often limited by the presence of physiological (epithelial tight junctions), biochemical (efflux transporters and enzymatic degradation) and chemical (size, lipophilicity, molecular weight, charge, etc.) barriers. These barriers may cause many potential therapeutics to be dropped from the preliminary screening portfolio and subsequent entry into the market. Transporter targeted delivery has become a powerful approach to deliver drugs to target tissues because of the ability of the transporter to translocate the drug to intracellular organelles at a higher rate. This review highlights studies employing SMVT transporter as a target for drug delivery to improve bioavailability and investigate the feasibility of developing SMVT targeted drug delivery systems. PMID:22420308

  4. Optimization of Azimuth Angle Settings in Polarizer-Compensator-Sample-Analyzer Off-Null Ellipsometry

    Microsoft Academic Search

    Guoliang Wang; Hans Arwin; Roger Jansson

    2003-01-01

    The dependence of the azimuth angle settings on the change in off-null intensity of a polarizer-compensator-sample-analyzer ellipsometer owing to changes in sample properties is studied. First, a closed-form expression for the relationship between azimuth angles that fulfill the null condition is presented. An approximation for the off-null light intensity near null that is valid for small changes of the p

  5. Angular Dependence of Transport AC Losses in Superconducting Wire with Position-Dependent Critical Current Density in a DC Magnetic Field

    NASA Astrophysics Data System (ADS)

    Su, Xing-liang; Xiong, Li-ting; Gao, Yuan-wen; Zhou, You-he

    2013-07-01

    Transport AC losses play a very important role in high temperature superconductors (HTSs), which usually carry AC transport current under applied magnetic field in typical application-like conditions. In this paper, we propose the analytical formula for transport AC losses in HTS wire by considering critical current density of both inhomogeneous and anisotropic field dependent. The angular dependence of critical current density is described by effective mass theory, and the HTS wire has inhomogeneous distribution cross-section of critical current density. We calculate the angular dependence of normalized AC losses under different DC applied magnetic fields. The numerical results of this formula agree well with the experiment data and are better than the results of Norris formula. This analytical formula can explain the deviation of experimental transport current losses from the Norris formula and apply to calculate transport AC losses in realistic practical condition.

  6. An improved azimuthal estimator for conventional SSR

    NASA Astrophysics Data System (ADS)

    Galati, G.; Studer, F. A.

    Azimuth estimators based on target 'begin' and 'end' are primarily conceived for the purposes of detection: the azimuth estimate is a side-product. Attention is presently given to an improved estimator based on the maximum likelihood estimator approach, which is especially suited to such specific azimuth estimation problems as missed replies and which takes advantage of the high S/N and steady-target characteristics of the secondary surveillance radar/identification friend-or-foe applications. The estimation is completely characterized by filter impulse response, whose shape is optimally designed according to the one-way power radiation of the antenna and the linear or logarithmic receiver detector characteristics.

  7. Anion- and Proton-Dependent Gating of ClC-4 Anion/Proton Transporter under Uncoupling Conditions

    PubMed Central

    Orhan, Gökce; Fahlke, Christoph; Alekov, Alexi K.

    2011-01-01

    ClC-4 is a secondary active transporter that exchanges Cl? ions and H+ with a 2:1 stoichiometry. In external SCN?, ClC-4 becomes uncoupled and transports anions with high unitary transport rate. Upon voltage steps, the number of active transporters varies in a time-dependent manner, resembling voltage-dependent gating of ion channels. We here investigated modification of the voltage dependence of uncoupled ClC-4 by protons and anions to quantify association of substrates with the transporter. External acidification shifts voltage dependence of ClC-4 transport to more positive potentials and leads to reduced transport currents. Internal pH changes had less pronounced effects. Uncoupled ClC-4 transport is facilitated by elevated external [SCN?] but impaired by internal Cl? and I?. Block by internal anions indicates the existence of an internal anion-binding site with high affinity that is not present in ClC channels. The voltage dependence of ClC-4 coupled transport is modulated by external protons and internal Cl? in a manner similar to what is observed under uncoupling conditions. Our data illustrate functional differences but also similarities between ClC channels and transporters. PMID:21354396

  8. TIME-DEPENDENT PERPENDICULAR TRANSPORT OF FAST CHARGED PARTICLES IN A TURBULENT MAGNETIC FIELD

    SciTech Connect

    Fraschetti, F.; Jokipii, J. R. [Departments of Planetary Sciences and Astronomy, University of Arizona, Tucson, AZ 85721 (United States)

    2011-06-20

    We present an analytic derivation of the temporal dependence of the perpendicular transport coefficient of charged particles in magnetostatic turbulence, for times smaller than the time needed for charged particles to travel the turbulence correlation length. This time window is left unexplored in most transport models. In our analysis all magnetic scales are taken to be much larger than the particle gyroradius, so that perpendicular transport is assumed to be dominated by the guiding center motion. Particle drift from the local magnetic field lines (MFLs) and magnetic field line random walk are evaluated separately for slab and three-dimensional (3D) isotropic turbulence. Contributions of wavelength scales shorter and longer than the turbulence coherence length are compared. In contrast to the slab case, particles in 3D isotropic turbulence unexpectedly diffuse from local MFLs; this result questions the common assumption that particle magnetization is independent of turbulence geometry. Extensions of this model will allow for a study of solar wind anisotropies.

  9. Azimuthal Resistivity Investigation of an Unconfined Aquifer at the Hanford Integrated Field Research Challenge Site

    NASA Astrophysics Data System (ADS)

    Greenwood, W. J.; Ward, A. L.; Versteeg, R. J.; Johnson, T. C.; Draper, K.

    2009-12-01

    Developing a robust large-scale groundwater contaminate transport model requires quantifying the effect of heterogeneity and anisotropy on solute transport. Here we investigated the feasibility of using surface azimuthal resistivity methods to characterize near-surface anisotropy and heterogeneity in order to improve the conceptual model for uranium transport through unconsolidated sediment at the Integrated Field Research Challenge Site (IFRC) which borders the Columbia River. A generalized azimuthal resistivity array was constructed with seven telescoping radii and 15° rotations between each electrode. Azimuthal array data were acquired by multiplexing with the MPT-DAS1 system connected to 172 surface electrodes. Array geometries included the square array, arrow array, offset wenner and equatorial dipole-dipole. Effective depths of exploration ranged between 5 and 57 m. Results from the upper 5m of exploration depth exhibit an isotropic resistivity which is consistent with the excavation and homogonous fill depth of the waste ponds at the IFRC. Exploration depths beyond 5 m are influenced by the Hanford and Ringold Formations. These formations exhibit a strong anisotropic resistivity which increases with depth. Assuming that the response is entirely controlled by hydrologic anisotropy, these azimuthal resistivity data suggest a preferential path with a mean azimuth between 150° and 170°. This azimuthal resistivity trend coincides with an incision feature in the Ringold formation measured in a suite of core logs and is consistent with the trajectory of a tracer plume from an injection test conducted in March 2009. Surface azimuthal resistivity methods may also have application in characterizing localized anisotropy and heterogeneity within shallow alluvial deposits at Hanford allowing for the optimal placement of tracer injections and borehole electrodes.

  10. Cell shape-dependent rectification of surface receptor transport in a sinusoidal electric field.

    PubMed Central

    Lee, R C; Gowrishankar, T R; Basch, R M; Patel, P K; Golan, D E

    1993-01-01

    In the presence of an extracellular electric field, transport dynamics of cell surface receptors represent a balance between electromigration and mutual diffusion. Because mutual diffusion is highly dependent on surface geometry, certain asymmetrical cell shapes effectively create an anisotropic resistance to receptor electromigration. If the resistance to receptor transport along a single axis is anisotropic, then an applied sinusoidal electric field will drive a net time-average receptor displacement, effectively rectifying receptor transport. To quantify the importance of this effect, a finite difference mathematical model was formulated and used to describe charged receptor transport in the plane of a plasma membrane. Representative values for receptor electromigration mobility and diffusivity were used. Model responses were examined for low frequency (10(-4)-10 Hz) 10-V/cm fields and compared with experimental measurements of receptor back-diffusion in human fibroblasts. It was found that receptor transport rectification behaved as a low-pass filter; at the tapered ends of cells, sinusoidal electric fields in the 10(-3) Hz frequency range caused a time-averaged accumulation of receptors as great as 2.5 times the initial uniform concentration. The extent of effective rectification of receptor transport was dependent on the rate of geometrical taper. Model studies also demonstrated that receptor crowding could alter transmembrane potential by an order of magnitude more than the transmembrane potential directly induced by the field. These studies suggest that cell shape is important in governing interactions between alternating current (ac) electric fields and cell surface receptors. PMID:8381681

  11. Martian global dust storms - Zonally symmetric numerical simulations including size-dependent particle transport

    NASA Technical Reports Server (NTRS)

    Murphy, James R.; Haberle, Robert M.; Toon, Owen B.; Pollack, James B.

    1993-01-01

    A zonally symmetric primitive-equation grid-point model of the Martian atmosphere is coupled with an aerosol transport/microphysical model in order to numerically investigate the size-dependent transport of dust particles in the Martian atmosphere. The coupled model accounts for diabatic heating due to a radiatively active evolving dust field, but neglects feedbacks between atmosphere-surface interactions and surface dust lifting. The differing suspension lifetimes of dust particles of various sizes (radius = 1-80 microns), in conjunction with spatially varying atmospheric dynamics, result in latitudinal differences in several measurements of the column integrated particle concentration. This work indicates the importance of considering the full range of particle sizes (and shapes) of the suspended dust during Martian global dust storms and their impact upon the spatial extent and wavelength-dependent radiative influence of such storms.

  12. Chirality-dependent transport in double-walled carbon nanotube assemblies: the role of inner tubes.

    PubMed

    Fujisawa, Kazunori; Komiyama, Keita; Muramatsu, Hiroyuki; Shimamoto, Daisuke; Tojo, Tomohiro; Kim, Yoong Ahm; Hayashi, Takuya; Endo, Morinobu; Oshida, Kyoichi; Terrones, Mauricio; Dresselhaus, Mildred S

    2011-09-27

    A fundamental understanding of the electrical properties of carbon nanotubes is vital when fabricating high-performance polymeric composites as well as transparent conductive films. Herein, the chirality-dependent transport mechanisms in peapod- and chemical vapor deposition-grown double-walled carbon nanotubes (DWNTs) films are discussed by identifying the chiralities of the inner and the outer tubes using fast Fourier transform image processing, as well as optical studies (e.g., Raman, UV, and photoluminescence spectroscopies). The observed conduction mechanisms are strongly dependent on the total fraction of the metallic inner and outer tubes within the DWNT samples. Furthermore, the contribution of the inner tubes to the electronic transport properties of DWNT films is confirmed by photochemically deactivating the outer tubes in both types of DWNT samples. PMID:21838288

  13. pH-dependent transport of metals through a reactive porous medium

    NASA Astrophysics Data System (ADS)

    Prigiobbe, V.; Bryant, S. L.

    2013-12-01

    Here we present a study on the effect of pH-dependent adsorption and hydrodynamic dispersion on metal transport through a reactive porous medium with hydrophilic surface. We investigate how the migration of a certain fraction of a metal can be facilitated by its competitive adsorption with protons. We performed laboratory experiments using a chromatographic column filled with silica beads coated with hydrous ferric oxide (HFO) and flooded initially with an acidic solution (pH 3) and then with an alkaline solution (pH > 7) containing either sodium, potassium, lithium, calcium, magnesium, strontium, or barium cations. Concentrations were chosen for which nonclassical transport is predicted. Highly resolved breakthrough curves measured with inline ion chromatography allowed us to observe in all cases the formation of a fast wave/pulse traveling at the interstitial fluid velocity and a retarded front. Classical theory of reactive transport through porous media predicts the formation of only the retarded front and assumes that hydrodynamic dispersion only smooths it without introducing an additional wave. Therefore, the fast wave is a notable exception to this theory. The mechanism responsible for this phenomenon is due to the interplay between hydrodynamic dispersion and pH-dependent adsorption. Hydrodynamic dispersion broadens the metal concentration front at the inlet of the column and creates a mixing zone where the high-pH solution containing the metal mixes with the low-pH solution initially present in the system. The resulting pH of the mixing zone spans a range where both the adsorption and the retardation of the metal are negligible. This leads to the formation of a metal plume, which then separates from the retarded front traveling at the interstitial fluid velocity as an isolated pulse. This fast transport phenomenon operates independently of other modes of rapid transport, such as colloid-facilitated transport and flow in fractures. A one-dimensional reactive transport model for an incompressible fluid was developed combining surface complexation with mass conservation equations for a solute and the acidity (difference between the total proton and the hydroxide concentrations). In all cases, the model agrees with the measurements capturing the underlying physics of the overall transport behavior and it shows the identity of the cation affects the behavior quantitatively but not qualitatively. This indicates that the formation of the fast pulse is a general transport phenomenon. Its potential effects are on the performance of subsurface engineering infrastructures for pollutant containment, the mobilization of metal contaminants by brine acidified upon contact with CO2 during geologic carbon storage, and the chromatographic separation processes in industrial applications.

  14. Serum albumin promotes ATP-binding cassette transporter-dependent sterol uptake in yeast.

    PubMed

    Marek, Magdalena; Silvestro, Daniele; Fredslund, Maria D; Andersen, Tonni G; Pomorski, Thomas G

    2014-12-01

    Sterol uptake in fungi is a multistep process that involves interaction between external sterols and the cell wall, incorporation of sterol molecules into the plasma membrane, and subsequent integration into intracellular membranes for turnover. ATP-binding cassette (ABC) transporters have been implicated in sterol uptake, but key features of their activity remain to be elucidated. Here, we apply fluorescent cholesterol (NBD-cholesterol) to monitor sterol uptake under anaerobic and aerobic conditions in two fungal species, Candida glabrata (Cg) and Saccharomyces cerevisiae (Sc). We found that in both fungal species, ABC transporter-dependent uptake of cholesterol under anaerobic conditions and in mutants lacking HEM1 gene is promoted in the presence of the serum protein albumin that is able to bind the sterol molecule. Furthermore, the C. glabrata ABC transporter CgAus1p expressed in S. cerevisiae requires the presence of serum or albumin for efficient cholesterol uptake. These results suggest that albumin can serve as sterol donor in ABC transporter-dependent sterol uptake, a process potentially important for growth of C. glabrata inside infected humans. PMID:25331273

  15. Time and dose-dependent effects of protein kinase C on proximal bicarbonate transport

    Microsoft Academic Search

    Tong Wang; Yun Lai Chan

    1990-01-01

    Summary Activation of protein kinase C has been shown to cause both stimulation and inhibition of transport processes in the brush-border membrane and renal tubule. This study was designed to examine the dose-response nature and time-dependent effect of 4 ß-phorbol-12-myristate-13-acetate (PMA) on the rates of bicarbonate absorption (JHCO3) and fluid absorption (Jv) in the proximal convoluted tubule (PCT) of rat

  16. Evidence of sodium-dependent glucose transport in human erythroleukemia cells

    Microsoft Academic Search

    James R Bading; Austin K Mircheff; June Kan-Mitchell

    1996-01-01

    Sodium-dependent transport of D-glucose has been reported only in epithelial cells of small intestine and kidney, and well-differentiated tumors thereof. We observed a two-fold decrease (p < 0.05) in the intracellular distribution volume (V1ic, defined as steady-state intracellular uptake ÷ extracellular concentration) of the non-metabolized D-glucose analog 3-O-methylglucose (3-O-MG) when logarithmically growing K562 cells (ananaplastic human erythroleukemia) were incubated 3

  17. Multisystemic Treatment of Substance-Abusing and Dependent Delinquents: Outcomes, Treatment Fidelity, and Transportability

    Microsoft Academic Search

    Scott W. Henggeler; Susan G. Pickrel; Michael J. Brondino

    1999-01-01

    The effectiveness and transportability of multisystemic therapy (MST) were examined in a study that included 118 juvenile offenders meeting DSM-III-R criteria for substance abuse or dependence and their families. Participants were randomly assigned to receive MST versus usual community services. Outcome measures assessed drug use, criminal activity, and days in out-of-home placement at posttreatment (T2) and at a 6-month posttreatment

  18. Cell Cycle-Dependent Microtubule-Based Dynamic Transport of Cytoplasmic Dynein in Mammalian Cells

    Microsoft Academic Search

    Takuya Kobayashi; Takashi Murayama

    2009-01-01

    BackgroundCytoplasmic dynein complex is a large multi-subunit microtubule (MT)-associated molecular motor involved in various cellular functions including organelle positioning, vesicle transport and cell division. However, regulatory mechanism of the cell-cycle dependent distribution of dynein has not fully been understood.Methodology\\/Principal FindingsHere we report live-cell imaging of cytoplasmic dynein in HeLa cells, by expressing multifunctional green fluorescent protein (mfGFP)-tagged 74-kDa intermediate chain

  19. Aquaporin-4–dependent K+ and water transport modeled in brain extracellular space following neuroexcitation

    PubMed Central

    Jin, Byung-Ju; Zhang, Hua; Binder, Devin K.

    2013-01-01

    Potassium (K+) ions released into brain extracellular space (ECS) during neuroexcitation are efficiently taken up by astrocytes. Deletion of astrocyte water channel aquaporin-4 (AQP4) in mice alters neuroexcitation by reducing ECS [K+] accumulation and slowing K+ reuptake. These effects could involve AQP4-dependent: (a) K+ permeability, (b) resting ECS volume, (c) ECS contraction during K+ reuptake, and (d) diffusion-limited water/K+ transport coupling. To investigate the role of these mechanisms, we compared experimental data to predictions of a model of K+ and water uptake into astrocytes after neuronal release of K+ into the ECS. The model computed the kinetics of ECS [K+] and volume, with input parameters including initial ECS volume, astrocyte K+ conductance and water permeability, and diffusion in astrocyte cytoplasm. Numerical methods were developed to compute transport and diffusion for a nonstationary astrocyte–ECS interface. The modeling showed that mechanisms b–d, together, can predict experimentally observed impairment in K+ reuptake from the ECS in AQP4 deficiency, as well as altered K+ accumulation in the ECS after neuroexcitation, provided that astrocyte water permeability is sufficiently reduced in AQP4 deficiency and that solute diffusion in astrocyte cytoplasm is sufficiently low. The modeling thus provides a potential explanation for AQP4-dependent K+/water coupling in the ECS without requiring AQP4-dependent astrocyte K+ permeability. Our model links the physical and ion/water transport properties of brain cells with the dynamics of neuroexcitation, and supports the conclusion that reduced AQP4-dependent water transport is responsible for defective neuroexcitation in AQP4 deficiency. PMID:23277478

  20. Short- and Long- Time Transport Structures in a Three Dimensional Time Dependent Flow

    E-print Network

    Rodolphe Chabreyrie; Stefan G. Llewellyn Smith

    2014-05-08

    Lagrangian transport structures for three-dimensional and time-dependent fluid flows are of great interest in numerous applications, particularly for geophysical or oceanic flows. In such flows, chaotic transport and mixing can play important environmental and ecological roles, for examples in pollution spills or plankton migration. In such flows, where simulations or observations are typically available only over a short time, understanding the difference between short-time and long-time transport structures is critical. In this paper, we use a set of classical (i.e. Poincar\\'e section, Lyapunov exponent) and alternative (i.e. finite time Lyapunov exponent, Lagrangian coherent structures) tools from dynamical systems theory that analyze chaotic transport both qualitatively and quantitatively. With this set of tools we are able to reveal, identify and highlight differences between short- and long-time transport structures inside a flow composed of a primary horizontal contra-rotating vortex chain, small lateral oscillations and a weak Ekman pumping. The difference is mainly the existence of regular or extremely slowly developing chaotic regions that are only present at short time.

  1. Short- and Long- Time Transport Structures in a Three Dimensional Time Dependent Flow

    NASA Astrophysics Data System (ADS)

    Chabreyrie, Rodolphe; Llewellyn Smith, Stefan

    2012-11-01

    Lagrangian transport structures for three-dimensional and time-dependent fluid flows are of great interest in numerous applications, particularly for geophysical or oceanic flows. In such flows, chaotic transport and mixing can play important environmental and ecological roles, for examples in pollution spills or plankton migration. In such flows, where simulations or observations are typically available only over a short time, understanding the difference between short-time and long-time transport structures is critical. In this talk, we use a set of classical (i.e. Poincaré section, Lyapunov exponent) and alternative (i.e. finite time Lyapunov exponent, Lagrangian coherent structures) tools from dynamical systems theory that analyze chaotic transport both qualitatively and quantitatively. With this set of tools we are able to reveal, identify and highlight differences between short- and long-time transport structures inside a flow composed of a primary horizontal contra-rotating vortex chain, small lateral oscillations and a weak Ekman pumping. The difference is mainly the existence of regular or extremely slowly developing chaotic regions that are only present at short time. This research was funded by the ONR MURI Dynamical Systems Theory and Lagrangian Data Assimilation in 3D+1 Geophysical Fluid Dynamics.

  2. N-Glycosylation is required for Na{sup +}-dependent vitamin C transporter functionality

    SciTech Connect

    Subramanian, Veedamali S. [Departments of Medicine, Physiology and Biophysics, University of California, Irvine, CA 92697 (United States)], E-mail: vsubrama@uci.edu; Marchant, Jonathan S. [Department of Pharmacology, University of Minnesota Medical School, MN 55455 (United States); Reidling, Jack C. [Departments of Medicine, Physiology and Biophysics, University of California, Irvine, CA 92697 (United States); Said, Hamid M. [Departments of Medicine, Physiology and Biophysics, University of California, Irvine, CA 92697 (United States); Department of Veterans Affairs Medical Center, Long Beach, CA 90822 (United States)

    2008-09-12

    The human sodium-dependent vitamin C transporters (hSVCT1 and hSVCT2) mediate cellular uptake of ascorbic acid. Both these transporters contain potential sites for N-glycosylation in their extracellular domains (Asn-138, Asn-144 [hSVCT1]; Asn-188, Asn-196 [hSVCT2]), however the role of N-glycosylation in transporter function is unexplored. On the basis of the result that tunicamycin decreased {sup 14}C-ascorbic acid uptake in HepG2 cells, we systematically ablated all consensus N-glycosylation sites in hSVCT1 and hSVCT2 to resolve any effects on ascorbic acid uptake, transporter expression and targeting. We show that removal of individual N-glycosylation sites significantly impairs protein expression and consequently ascorbic acid uptake for hSVCT1 mutants (N138Q is retained intracellularly) and for hSVCT2 mutants (all of which reach the cell surface). N-Glycosylation is therefore essential for vitamin C transporter functionality.

  3. Mechanism of Orientation-Dependent Asymmetric Charge Transport in Tunneling Junctions Comprising Photosystem I.

    PubMed

    Castañeda Ocampo, Olga E; Gordiichuk, Pavlo; Catarci, Stefano; Gautier, Daniel A; Herrmann, Andreas; Chiechi, Ryan C

    2015-07-01

    Recently, photoactive proteins have gained a lot of attention due to their incorporation into bioinspired (photo)electrochemical and solar cells. This paper describes the measurement of the asymmetry of current transport of self-assembled monolayers (SAMs) of the entire photosystem I (PSI) protein complex (not the isolated reaction center, RCI), on two different "director SAMs" supported by ultraflat Au substrates. The director SAMs induce the preferential orientation of PSI, which manifest as asymmetry in tunneling charge-transport. We measured the oriented SAMs of PSI using eutectic Ga-In (EGaIn), a large-area technique, and conducting probe atomic force microscopy (CP-AFM), a single-complex technique, and determined that the transport properties are comparable. By varying the temperatures at which the measurements were performed, we found that there is no measurable dependence of the current on temperature from ±0.1 to ±1.0 V bias, and thus, we suggest tunneling as the mechanism for transport; there are no thermally activated (e.g., hopping) processes. Therefore, it is likely that relaxation in the electron transport chain is not responsible for the asymmetry in the conductance of SAMs of PSI complexes in these junctions, which we ascribe instead to the presence of a large, net dipole moment present in PSI. PMID:26057523

  4. Temperature-dependent electrical transport in ferroelectric organic field-effect transistors

    NASA Astrophysics Data System (ADS)

    Laudari, Amrit; Guha, Suchismita

    2015-03-01

    Ferroelectric dielectrics, permitting access to nearly an order of magnitude range of polarization with temperature as the tuning parameter, offer a great test-bed to monitor the changes in interfacial transport in organic field-effect transistors (OFETs) as the polarization strength is tuned. Temperature-dependent transport studies have been carried out from pentacene and other organic semiconductor-based OFETs using the ferroelectric copolymer poly(vinylidene fluoride-co-trifluoroethylene) (PVDF-TrFe) as a gate insulating layer. By fits to an Arrhenius-type dependence of the charge carrier mobility as a function of temperature, the activation energy in the ferroelectric phase is found to increase as the thickness of the PVDF-TrFe layer increases. For thicknesses of the dielectric layer above 100 nm, the activation energy is found to be greater than 150 meV, which greatly reduces in the paraelectric phase of the dielectric. The weak temperature-dependence of the charge carrier mobility in the ferroelectric phase of PVDF-TrFe may be attributed to a polarization fluctuation driven transport. The threshold voltage decreases upon increasing temperatures with a large change above the ferroelectric to paraelectric phase transition temperature. This work was supported by National Science Foundation under Grant No. ECCS-1305642.

  5. Time-Dependent DIII-D Heat Transport Simulations Using Neural-Network Models

    NASA Astrophysics Data System (ADS)

    Penna, J. M.; Smith, S. P.; Meneghini, O.; Luna, C. J.

    2014-10-01

    The neural network transport model BRAINFUSE has been developed to produce transport fluxes based on local parameters. The BRAIN-FUSE model has been integrated into the transport modeling framework ONETWO in order to develop time dependent solutions and has been validated by artificially varying the input neutral beam power and comparing the output to DIII-D scans. These efforts have led to the development of a time-dependent workflow within the OMFIT integrated modeling framework. The new work flow can evolve the electron and ion temperatures as a function of time dependent sources and equilibria. The effects of different engineering parameters can be explored and optimized in support of DIII-D operations. The efficiency of this workflow enables planning plasma operations of next-day experiments, as will be required for ITER. Work supported in part by the National Undergraduate Fellowship Program in Plasma Physics and Fusion Energy Sciences and the US Department of Energy under DE-FG02-94ER54235 & DE-FC02-04ER54698.

  6. A Modified Direct-Reading Azimuth Protractor

    ERIC Educational Resources Information Center

    Larson, William C.; Pugliese, Joseph M.

    1977-01-01

    Describes the construction of a direct-reading azimuth protractor (DRAP) used for mapping fracture and joint-surface orientations in underground mines where magnetic disturbances affect typical geologic pocket transit. (SL)

  7. Gestational Age-Dependent Changes in Gene Expression of Metabolic Enzymes and Transporters in Pregnant Mice

    PubMed Central

    Shuster, Diana L.; Bammler, Theo K.; Beyer, Richard P.; MacDonald, James W.; Tsai, Jesse M.; Farin, Frederico M.; Hebert, Mary F.; Thummel, Kenneth E.

    2013-01-01

    Pregnancy-induced changes in drug pharmacokinetics can be explained by changes in expression of drug-metabolizing enzymes and transporters and/or normal physiology. In this study, we determined gestational age-dependent expression profiles for all metabolic enzyme and transporter genes in the maternal liver, kidney, small intestine, and placenta of pregnant mice by microarray analysis. We specifically examined the expression of genes important for xenobiotic, bile acid, and steroid hormone metabolism and disposition, namely, cytochrome P450s (Cyp), UDP-glucuronosyltranserases (Ugt), sulfotransferases (Sult), and ATP-binding cassette (Abc), solute carrier (Slc), and solute carrier organic anion (Slco) transporters. Few Ugt and Sult genes were affected by pregnancy. Cyp17a1 expression in the maternal liver increased 3- to 10-fold during pregnancy, which was the largest observed change in the maternal tissues. Cyp1a2, most Cyp2 isoforms, Cyp3a11, and Cyp3a13 expression in the liver decreased on gestation days (gd) 15 and 19 compared with nonpregnant controls (gd 0). In contrast, Cyp2d40, Cyp3a16, Cyp3a41a, Cyp3a41b, and Cyp3a44 in the liver were induced throughout pregnancy. In the placenta, Cyp expression on gd 10 and 15 was upregulated compared with gd 19. Notable changes were also observed in Abc and Slc transporters. Abcc3 expression in the liver and Abcb1a, Abcc4, and Slco4c1 expression in the kidney were downregulated on gd 15 and 19. In the placenta, Slc22a3 (Oct3) expression on gd 10 was 90% lower than that on gd 15 and 19. This study demonstrates important gestational age-dependent expression of metabolic enzyme and transporter genes, which may have mechanistic relevance to drug disposition in human pregnancy. PMID:23175668

  8. Mechanisms underlying azimuth selectivity in the auditory cortex of the pallid bat

    PubMed Central

    Razak, K.A.

    2012-01-01

    This study focused on mechanisms underlying azimuth selectivity in the primary auditory cortex (A1) of pallid bats. The pallid bat listens to prey-generated noise (5–35 kHz) to localize and hunt terrestrial prey. The region of A1 tuned between 5–35 kHz consists of two clusters of neurons distinguished by interaural intensity difference (IID) selectivity: binaurally inhibited (EI) and peaked. The first aim of this study was to use sequential dichotic/free-field stimulation to test the hypothesis that IID is the primary cue underlying azimuth selectivity in neurons tuned in the prey-generated noise frequency band. IID selectivity and ear directionality at the neuron’s characteristic frequency (CF) were used to predict azimuth selectivity functions. The predicted azimuth selectivity was compared with the actual azimuth selectivity from the same neurons. Prediction accuracy was similarly high for EI neurons and peaked neurons with low CF, whereas predictions were increasingly inaccurate with increasing CF among the peaked neurons. The second aim of this study was to compare azimuth selectivity obtained with noise and CF tones to determine the extent to which stimulus bandwidth influences azimuth selectivity in neurons with different binaural properties. The azimuth selectivity functions were similar for the two stimuli in the majority of EI neurons. A greater percentage of peaked neurons showed differences in their azimuth selectivity for noise and tones. This included neurons with multiple peaks when tested with tones and a single peak when tested with noise. Taken together, data from the two aims suggest that azimuth tuning of EI neurons is primarily dictated by IID sensitivity at CF. Peaked neurons, particularly those with high CF, may integrate IID sensitivity across frequency to generate azimuth selectivity for broadband sound. The data are consistent with those found in cat and ferret A1 in that binaurally facilitated neurons depend to a greater extent (compared to EI neurons) on spectral integration of binaural properties to generate azimuth selectivity for broadband stimuli. PMID:22641192

  9. Transverse spin azimuthal asymmetries in SIDIS at COMPASS: Multidimensional analysis

    E-print Network

    Parsamyan, Bakur

    2015-01-01

    COMPASS is a high-energy physics experiment operating at the SPS at CERN. Wide physics program of the experiment comprises study of hadron structure and spectroscopy with high energy muon and hadrons beams. As for the muon-program, one of the important objectives of the COMPASS experiment is the exploration of the transverse spin structure of the nucleon via spin (in)dependent azimuthal asymmetries in single-hadron production in deep inelastic scattering of polarized leptons off transversely polarized target. For this purpose a series of measurements were made in COMPASS, using 160 GeV/c longitudinally polarized muon beam and transversely polarized 6LiD (in 2002, 2003 and 2004) and NH3 (in 2007 and 2010) targets. The experimental results obtained by COMPASS for unpolarized target azimuthal asymmetries, Sivers and Collins effects and other azimuthal observables play an important role in the general understanding of the three-dimensional nature of the nucleon. Giving access to the entire "twsit-2" set of transv...

  10. Azimuthal-spin-wave-mode-driven vortex-core reversals

    NASA Astrophysics Data System (ADS)

    Yoo, Myoung-Woo; Kim, Sang-Koog

    2015-01-01

    We studied, by micromagnetic numerical calculations, asymmetric vortex-core reversals driven by the m = -1 and m = +1 azimuthal spin-wave modes' excitations in soft magnetic circular nano-disks. We addressed the similarities and differences between the asymmetric core reversals in terms of the temporal evolutions of the correlated core-motion speed, locally concentrated perpendicular gyrofield, and magnetization dip near the original vortex core. The criterion for the core reversals was found to be the magnetization dip that must reach the out-of-plane magnetization component, mz = -p, with the initial polarization p, where p = +1 (-1) for the upward (downward) core magnetization. The core-motion speed and the associated perpendicular gyrofield, variable and controllable with static perpendicular field, Hz, applied perpendicularly to the disk plane, must reach their threshold values to meet the ultimate core-reversal criterion. Also, we determined the Hz strength and direction dependence of the core-switching time and threshold exciting field strength required for the core reversals, whose parameters are essential in the application aspect. This work offers deeper insights into the azimuthal spin-wave-driven core-reversal dynamics as well as an efficient means of controlling the azimuthal-modes-driven core reversals.

  11. Globally Visualizing the Microtubule-Dependent Transport Behaviors of Influenza Virus in Live Cells

    PubMed Central

    2015-01-01

    Understanding the microtubule-dependent behaviors of viruses in live cells is very meaningful for revealing the mechanisms of virus infection and endocytosis. Herein, we used a quantum dots-based single-particle tracking technique to dynamically and globally visualize the microtubule-dependent transport behaviors of influenza virus in live cells. We found that the intersection configuration of microtubules can interfere with the transport behaviors of the virus in live cells, which lead to the changing and long-time pausing of the transport behavior of viruses. Our results revealed that most of the viruses moved along straight microtubules rapidly and unidirectionally from the cell periphery to the microtubule organizing center (MTOC) near the bottom of the cell, and the viruses were confined in the grid of microtubules near the top of the cell and at the MTOC near the bottom of the cell. These results provided deep insights into the influence of entire microtubule geometry on the virus infection. PMID:24678700

  12. Fully energy-dependent HZETRN (a galactic cosmic-ray transport code)

    NASA Technical Reports Server (NTRS)

    Shinn, Judy L.; John, Sarah; Tripathi, Ram K.; Norbury, John W.; Wilson, John W.; Townsend, Lawrence W.

    1992-01-01

    For extended manned space missions, the radiation shielding design requires efficient and accurate cosmic-ray transport codes that can handle the physics processes in detail. The Langley Research Center galactic cosmic-ray transport code (HZETRN) is currently under development for such design use. The cross sections for the production of secondary nucleons in the existing HZETRN code are energy dependent only for nucleon collisions. The approximation of energy-independent, heavy-ion fragmentation cross section is now removed by implementing a mathematically simplified energy-dependent stepping formalism for heavy ions. The cross section at each computational grid is obtained by linear interpolation from a few tabulated data to minimize computing time. Test runs were made for galactic cosmic-ray transport through a liquid hydrogen shield and a water shield at solar minimum. The results show no appreciable change in total fluxes or computing time compared with energy-independent calculations. Differences in high LET (linear energy transfer) spectra are noted, however, because of the large variation in cross sections at the low-energy region. The high LET components are significantly higher in the new code and have important implications on biological risk estimates for heavy-ion exposure.

  13. Energy dependence of jet transport parameter and parton saturationin quark-gluon plasma

    SciTech Connect

    Casalderrey-Solana, Jorge; Wang, Xin-Nian

    2007-06-24

    We study the evolution and saturation of the gluondistribution function in the quark-gluon plasma as probed by apropagating parton and its effect on the computation of jet quenching ortransport parameter $\\hat q $. For thermal partons, the saturation scale$Q2_s$ is found to be proportional to the Debye screening mass $\\mu_D2$.For hard probes, evolution at small $x=Q2_s/6ET$ leads to jet energydependence of hat q. We study this dependence for both a conformal gaugetheory in weak and strong coupling limit and for (pure gluon) QCD. Theenergy dependence can be used to extract the shear viscosity $\\eta$ ofthe medium since $\\eta$ can be related to the transport parameter forthermal partons in a transport description. We also derive upper boundson the transport parameter for both energetic and thermal partons. Thelater leads to a lower bound on shear viscosity-to-entropy density ratiowhich is consistent with the conjectured lower bound $\\eta/s\\geq 1/4\\pi$.Implications on the study of jet quenching at RHIC and LHC and the bulkproperties of the dense matter are discussed.

  14. Z dependence of the core impurity transport in ASDEX Upgrade H mode discharges

    NASA Astrophysics Data System (ADS)

    Dux, R.; Peeters, A. G.; Gude, A.; Kallenbach, A.; Neu, R.; ASDEX Upgrade Team

    1999-11-01

    The dependence of core plasma impurity transport on the Z number has been investigated for ASDEX Upgrade H mode discharges. For the elements Ne, Ar, Kr and Xe the diffusion coefficient in the centre is D <= 6 × 10-2m2/s and rises with the radial distance from the centre. With increasing Z number the transport becomes strongly convective with inward directed drift velocities that produce very peaked impurity densities for high Z. The inward drift decreases with decreasing deuterium density gradient. Neoclassical transport of the impurities has been calculated numerically. The calculated diffusion coefficient and drift velocity are close to the experimental values for the lower-Z elements Ne and Ar. However, for high Z, the calculated diffusion coefficient is smaller by a factor of up to 2.5 and the inward drift velocity is too small by a factor of 10. Toroidal rotation of the plasma that leads to an increased impurity density on the outboard side of the flux surfaces is not taken into account by the neoclassical calculations. Inboard/outboard asymmetries are not present for Ar and Ne with toroidal Mach number Mtor around 1. However, for heavier elements than Kr with Mtor approx 2 and an outboard/inboard ratio of approx 1.5, poloidal variation of the impurity density is important and might account for the discrepancy between the measured and calculated transport coefficients.

  15. Time dependent simulation of cosmic-ray shocks including Alfven transport

    NASA Technical Reports Server (NTRS)

    Jones, T. W.

    1993-01-01

    Time evolution of plane, cosmic-ray modified shocks was simulated numerically for the case with parallel magnetic fields. Computations were done in a 'three-fluid' dynamical model incorporating cosmic-ray and Alfven wave energy transport equations. Nonlinear feedback from the cosmic-rays and Alfven waves is included in the equation of motion for the underlying plasma, as is the finite propagation speed and energy dissipation of the Alfven waves. Exploratory results confirm earlier, steady state analyses that found these Alfven transport effects to be potentially important when the upstream Alfven speed and gas sound speeds are comparable. As noted earlier Alfven transport effects tend to reduce the transfer of energy through a shock from gas to energetic particles. These studies show as well that the time scale for modification of the shock is altered in nonlinear ways. It is clear, however, that the consequences of Alfven transport are strongly model dependent and that both advection of cosmic-rays by the waves and dissipation of wave energy in the plasma will be important to model correctly when quantitative results are needed. Comparison is made between simulations based on a constant diffusion coefficient and more realistic diffusion models allowing the diffusion coefficient to vary in response to changes in Alfven wave intensity. No really substantive differences were found between them.

  16. Time-dependent simulation of cosmic-ray shocks, including Alfven transport

    NASA Technical Reports Server (NTRS)

    Jones, T. W.

    1994-01-01

    Time evolution of plane, cosmic-ray modified shocks has been simulated numerically for the case with parallel magnetic fields. Computations were done in a 'three-fluid' dynamical model incorporating cosmic-ray and Alfven-wave energy transport equations. Nonlinear feedback from the cosmic rays and Alfven waves is included in the equation of motion for the underlying plasma, as is the finite propagation speed and energy dissipation of the Alfven waves. Exploratory results confirm earlier, steady state analyses that found these Alfven transport effects to be potentially important when the upstream Alfven speed and gas sound speeds are comparable. As noted earlier, Alfven transport effects tend to reduce the transfer of energy through a shock from gas to energetic particles. These studies show as well that the timescale for modification of the shock is altered in nonlinear ways. It is clear, however, that the consequences of Alfven transport are strongly model dependent and that both advection of cosmic rays by the waves and dissipation of wave energy in the plasma will be important to model correctly when quantitative results are needed. Comparison is made between simulations based on a constant diffusion coefficient and more realistic diffusion models allowing the diffusion coefficient to vary in response to changes in Alfven wave intensity. No really substantive differences were found between them.

  17. Multicomponent, multi-azimuth pre-stack seismic waveform inversion for azimuthally anisotropic media using a parallel and computationally efficient non-dominated sorting genetic algorithm

    NASA Astrophysics Data System (ADS)

    Li, Tao; Mallick, Subhashis

    2015-02-01

    Consideration of azimuthal anisotropy, at least to an orthorhombic symmetry is important in exploring the naturally fractured and unconventional hydrocarbon reservoirs. Full waveform inversion of multicomponent seismic data can, in principle, provide more robust estimates of subsurface elastic parameters and density than the inversion of single component (P wave) seismic data. In addition, azimuthally dependent anisotropy can only be resolved by carefully studying the multicomponent seismic displacement data acquired and processed along different azimuths. Such an analysis needs an inversion algorithm capable of simultaneously optimizing multiple objectives, one for each data component along each azimuth. These multicomponent and multi-azimuthal seismic inversions are non-linear with non-unique solutions; it is therefore appropriate to treat the objectives as a vector and simultaneously optimize each of its components such that the optimal set of solutions could be obtained. The fast non-dominated sorting genetic algorithm (NSGA II) is a robust stochastic global search method capable of handling multiple objectives, but its computational expense increases with increasing number of objectives and the number of model parameters to be inverted for. In addition, an accurate extraction of subsurface azimuthal anisotropy requires multicomponent seismic data acquired at a fine spatial resolution along many source-to-receiver azimuths. Because routine acquisition of such data is prohibitively expensive, they are typically available along two or at most three azimuthal orientations at a spatial resolution where such an inversion could be applied. This paper proposes a novel multi-objective methodology using a parallelized version of NSGA II for waveform inversion of multicomponent seismic displacement data along two azimuths. By scaling the objectives prior to ranking, redefining the crowding distance as functions of the scaled objective and the model spaces, and varying the crossover and mutation parameters over generations, the proposed methodology is also an improvement of the original NSGA II in overall computational efficiency, preservation of population diversity, and rapid sampling of the model space. By first inverting the near-offset pre-stack data for the background isotropic properties and obtaining constraints on the vertical velocities, followed by an inversion of the long-offset data, it is demonstrated that the proposed method can reliably estimate density and azimuthally anisotropic subsurface properties up to the complexity of an orthorhombic symmetry on noisy synthetic data computed from a model based on a real well log under an assumption of 1-D subsurface layers where the ambiguities between lateral heterogeneity and anisotropy could be ignored. In addition, a practical way to approximately compute the uncertainty values in the derived parameters using the method is also demonstrated.

  18. Selective sodium-dependent glucose transporter 1 inhibitors block glucose absorption and impair glucose-dependent insulinotropic peptide release.

    PubMed

    Dobbins, Robert L; Greenway, Frank L; Chen, Lihong; Liu, Yaping; Breed, Sharon L; Andrews, Susan M; Wald, Jeffrey A; Walker, Ann; Smith, Chari D

    2015-06-01

    GSK-1614235 and KGA-2727 are potent, selective inhibitors of the SGLT1 sodium-dependent glucose transporter. Nonclinical (KGA-2727) and clinical (GSK-1614235) trials assessed translation of SGLT1 inhibitor effects from rats to normal human physiology. In rats, KGA-2727 (0.1 mg/kg) or vehicle was given before oral administration of 3-O-methyl-?-d-glucopyranose (3-O-methylglucose, 3-OMG) containing 3-[(3)H]OMG tracer. Tracer absorption and distribution were assessed from plasma, urine, and fecal samples. SGLT1 inhibition reduced urine 3-OMG recovery and increased fecal excretion. SGLT1 inhibitor effects on plasma glucose, insulin, gastric inhibitory peptide (GIP), and glucagon-like peptide-1 (GLP-1) concentrations were also measured during a standard meal. Incremental glucose, insulin, and GIP concentrations were decreased, indicating downregulation of ?-cell and K cell secretion. Minimal effects were observed in the secretion of the L cell product, GLP-1. With the use of a three-way, crossover design, 12 healthy human subjects received placebo or 20 mg GSK-1614235 immediately before or after a meal. Five minutes into the meal, 3-OMG was ingested. Postmeal dosing had little impact, yet premeal dosing delayed and reduced 3-OMG absorption, with an AUC0-10 of 231 ± 31 vs. 446 ± 31 ?g·h(-1)·ml(-1), for placebo. Recovery of tracer in urine was 1.2 ± 0.7 g for premeal dosing and 2.2 ± 0.1 g for placebo. Incremental concentrations of insulin, C-peptide, and GIP were reduced for 2 h with premeal GSK-1614235. Total GLP-1 concentrations were significantly increased, and a trend for increased peptide YY (PYY) was noted. SGLT1 inhibitors block intestinal glucose absorption and reduce GIP secretion in rats and humans, suggesting SGLT1 glucose transport is critical for GIP release. Conversely, GLP-1 and PYY secretion are enhanced by SGLT1 inhibition in humans. PMID:25767259

  19. Dissipative time-dependent quantum transport theory: Quantum interference and phonon induced decoherence dynamics

    NASA Astrophysics Data System (ADS)

    Zhang, Yu; Yam, ChiYung; Chen, GuanHua

    2015-04-01

    A time-dependent inelastic electron transport theory for strong electron-phonon interaction is established via the equations of motion method combined with the small polaron transformation. In this work, the dissipation via electron-phonon coupling is taken into account in the strong coupling regime, which validates the small polaron transformation. The corresponding equations of motion are developed, which are used to study the quantum interference effect and phonon-induced decoherence dynamics in molecular junctions. Numerical studies show clearly quantum interference effect of the transport electrons through two quasi-degenerate states with different couplings to the leads. We also found that the quantum interference can be suppressed by the electron-phonon interaction where the phase coherence is destroyed by phonon scattering. This indicates the importance of electron-phonon interaction in systems with prominent quantum interference effect.

  20. Alcohol and the calcium-dependent potassium transport of human erythrocytes

    SciTech Connect

    Harris, R.A.; Caldwell, K.K.

    1985-01-01

    In vitro exposure of human red blood cells to ethanol (100 and 400 mM) was found to increase the initial rate of calcium-dependent potassium efflux through the red cell membrane. This effect of ethanol was apparently not due to an elevation of the intracellular free calcium but rather to a direct action of the drug on the transport process as, (1) intracellular calcium concentrations were tightly buffered with EGTA, (2) ethanol did not alter the efflux of UVCa from the cells, and (3) dantrolene, which has been proposed to counteract the effect of ethanol on intracellular calcium levels in the erythrocyte, did not inhibit the stimulatory action of ethanol. The efflux of potassium from erythrocytes obtained from chronic alcoholics was not different from that of erythrocytes from non-alcoholic individuals. The relationship of these findings to neuronal potassium transport is discussed.

  1. Numerical solution of the time dependent neutron transport equation by the method of the characteristics

    SciTech Connect

    Talamo, Alberto, E-mail: alby@anl.gov [Nuclear Engineering Division, Argonne National Laboratory, 9700 South Cass Avenue, Lemont, IL 60439 (United States)] [Nuclear Engineering Division, Argonne National Laboratory, 9700 South Cass Avenue, Lemont, IL 60439 (United States)

    2013-05-01

    This study presents three numerical algorithms to solve the time dependent neutron transport equation by the method of the characteristics. The algorithms have been developed taking into account delayed neutrons and they have been implemented into the novel MCART code, which solves the neutron transport equation for two-dimensional geometry and an arbitrary number of energy groups. The MCART code uses regular mesh for the representation of the spatial domain, it models up-scattering, and takes advantage of OPENMP and OPENGL algorithms for parallel computing and plotting, respectively. The code has been benchmarked with the multiplication factor results of a Boiling Water Reactor, with the analytical results for a prompt jump transient in an infinite medium, and with PARTISN and TDTORT results for cross section and source transients. The numerical simulations have shown that only two numerical algorithms are stable for small time steps.

  2. Spin dependent transport in diluted magnetic semiconductor/superconductor tunnel junctions

    NASA Astrophysics Data System (ADS)

    Shokri, A. A.; Negarestani, S.

    2014-12-01

    A modification of Blonder-Tinkham-Klapwijk (BTK) model is proposed to describe transport properties of diluted magnetic semiconductor (DMS)/superconductor(SC)/DMS double tunneling junctions. Coherent spin-polarized transport is studied by taking into account the Andreev reflection on spatial variation of SC barrier parameters in the heterostructure. It is shown that the conductance spectrum exhibits an oscillatory behavior with quasi-particle energy, and the oscillation amplitude is reduced with increasing temperature. We also examine the dependence of tunneling magnetoresistance (TMR) on the barrier strength (?) and spin polarization (P) of two DMS layers. Our results show that TMR decreases with increasing temperature and barrier strength, which may be useful in designing the nano spin-valve devices based on DMS and SC materials.

  3. Frequency-dependent critical current and transport ac loss of superconductor strip and Roebel cable

    NASA Astrophysics Data System (ADS)

    Prasad Thakur, Kailash; Raj, Ashish; Brandt, Ernst Helmut; Kvitkovic, Jozef; Pamidi, Sastry V.

    2011-06-01

    The frequency-dependent critical current of a superconductor strip and Roebel cable has been studied using a 2D finite element simulation. It is shown that the critical current of the superconductor increases with frequency as f1/n, where n is the exponent of the power law flux creep model. Transport ac loss in a superconductor strip decreases with frequency as f - 2/n when the amplitude of the applied ac current is far less than its critical current. However, when the applied current is large and becomes comparable to the critical current, the transport ac loss decreases with frequency as 1/f. The analytical results are substantiated with available experimental data and the results of a 2D finite element simulation.

  4. Smith, E. R., and Kraus, N. C. 2007. Longshore and Sand Transport Calculated by Time-Dependent Shear Stress. Proceedings Coastal Sediments '07 Conference, ASCE Press, Reston,

    E-print Network

    US Army Corps of Engineers

    Smith, E. R., and Kraus, N. C. 2007. Longshore and Sand Transport Calculated by Time- Dependent SAND TRANSPORT CALCULATED BY TIME-DEPENDENT SHEAR STRESS Ernest R. Smith1 and Nicholas C. Kraus1 1. U.C.Kraus@erdc.usace.army.mil. Abstract: Based on longshore sand transport experiments performed in a large basin, measured sand transport

  5. Overexpression of the Auxin Binding PROTEIN1 Modulates PIN-Dependent Auxin Transport in Tobacco Cells

    PubMed Central

    ?ovanová, Milada; Sauer, Michael; Rychtá?, Jan; Friml, Ji?í; Petrášek, Jan; Zažímalová, Eva

    2013-01-01

    Background Auxin binding protein 1 (ABP1) is a putative auxin receptor and its function is indispensable for plant growth and development. ABP1 has been shown to be involved in auxin-dependent regulation of cell division and expansion, in plasma-membrane-related processes such as changes in transmembrane potential, and in the regulation of clathrin-dependent endocytosis. However, the ABP1-regulated downstream pathway remains elusive. Methodology/Principal Findings Using auxin transport assays and quantitative analysis of cellular morphology we show that ABP1 regulates auxin efflux from tobacco BY-2 cells. The overexpression of ABP1can counterbalance increased auxin efflux and auxin starvation phenotypes caused by the overexpression of PIN auxin efflux carrier. Relevant mechanism involves the ABP1-controlled vesicle trafficking processes, including positive regulation of endocytosis of PIN auxin efflux carriers, as indicated by fluorescence recovery after photobleaching (FRAP) and pharmacological manipulations. Conclusions/Significance The findings indicate the involvement of ABP1 in control of rate of auxin transport across plasma membrane emphasizing the role of ABP1 in regulation of PIN activity at the plasma membrane, and highlighting the relevance of ABP1 for the formation of developmentally important, PIN-dependent auxin gradients. PMID:23894588

  6. Multi-fluid transport code modeling of time-dependent recycling in ELMy H-mode

    SciTech Connect

    Pigarov, A. Yu.; Krasheninnikov, S. I.; Hollmann, E. M. [University of California at San Diego, La Jolla, California 92093 (United States); Rognlien, T. D.; Lasnier, C. J. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States); Unterberg, E. [Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)

    2014-06-15

    Simulations of a high-confinement-mode (H-mode) tokamak discharge with infrequent giant type-I ELMs are performed by the multi-fluid, multi-species, two-dimensional transport code UEDGE-MB, which incorporates the Macro-Blob approach for intermittent non-diffusive transport due to filamentary coherent structures observed during the Edge Localized Modes (ELMs) and simple time-dependent multi-parametric models for cross-field plasma transport coefficients and working gas inventory in material surfaces. Temporal evolutions of pedestal plasma profiles, divertor recycling, and wall inventory in a sequence of ELMs are studied and compared to the experimental time-dependent data. Short- and long-time-scale variations of the pedestal and divertor plasmas where the ELM is described as a sequence of macro-blobs are discussed. It is shown that the ELM recovery includes the phase of relatively dense and cold post-ELM divertor plasma evolving on a several ms scale, which is set by the transport properties of H-mode barrier. The global gas balance in the discharge is also analyzed. The calculated rates of working gas deposition during each ELM and wall outgassing between ELMs are compared to the ELM particle losses from the pedestal and neutral-beam-injection fueling rate, correspondingly. A sensitivity study of the pedestal and divertor plasmas to model assumptions for gas deposition and release on material surfaces is presented. The performed simulations show that the dynamics of pedestal particle inventory is dominated by the transient intense gas deposition into the wall during each ELM followed by continuous gas release between ELMs at roughly a constant rate.

  7. Multi-fluid transport code modeling of time-dependent recycling in ELMy H-mode

    SciTech Connect

    Pigarov, A. Yu. [University of California, San Diego; Krasheninnikov, S. I. [University of California, La Jolla; Rognlien, T. D. [Lawrence Livermore National Laboratory (LLNL); Hollmann, E. M. [University of California, San Diego; Lasnier, C. J. [Lawrence Livermore National Laboratory (LLNL); Unterberg, Ezekial A [ORNL

    2014-01-01

    Simulations of a high-confinement-mode (H-mode) tokamak discharge with infrequent giant type-I ELMs are performed by the multi-fluid, multi-species, two-dimensional transport code UEDGE-MB, which incorporates the Macro-Blob approach for intermittent non-diffusive transport due to filamentary coherent structures observed during the Edge Localized Modes (ELMs) and simple time-dependent multi-parametric models for cross-field plasma transport coefficients and working gas inventory in material surfaces. Temporal evolutions of pedestal plasma profiles, divertor recycling, and wall inventory in a sequence of ELMs are studied and compared to the experimental time-dependent data. Short- and long-time-scale variations of the pedestal and divertor plasmas where the ELM is described as a sequence of macro-blobs are discussed. It is shown that the ELM recovery includes the phase of relatively dense and cold post-ELM divertor plasma evolving on a several ms scale, which is set by the transport properties of H-mode barrier. The global gas balance in the discharge is also analyzed. The calculated rates of working gas deposition during each ELM and wall outgassing between ELMs are compared to the ELM particle losses from the pedestal and neutral-beam-injection fueling rate, correspondingly. A sensitivity study of the pedestal and divertor plasmas to model assumptions for gas deposition and release on material surfaces is presented. The performed simulations show that the dynamics of pedestal particle inventory is dominated by the transient intense gas deposition into the wall during each ELM followed by continuous gas release between ELMs at roughly a constant rate.

  8. A 96-well automated method to study inhibitors of human sodium-dependent D-glucose transport

    Microsoft Academic Search

    Francisco Castaneda; Rolf K.-H. Kinne

    2005-01-01

    The sodium-dependent D-glucose transporter (SGLT) family is involved in glucose uptake via intestinal absorption (SGLT1) or\\u000a renal reabsorption (SGLT1 and SGLT2). Current methods for the screening of inhibitors of SGLT transporters are complex, expensive\\u000a and very labor intensive, and have not been applied to human SGLT transporters. The purpose of the present study was to develop\\u000a an alternative 96-well automated

  9. One-Dimensional, Time-Dependent, Integral Neutron Transport For Inertial Confinement Fusion

    NASA Astrophysics Data System (ADS)

    Aplin, Carol S.

    Neutron transport is of great importance to inertial confinement fusion (ICF) for several reasons. An accurate neutron energy spectrum is necessary for tritium breeding purposes, and the deposition of energy in the ICF target by energetic neutrons born from fusion may have detrimental effects on the fusion burn. The goal of this research was to develop an accurate neutron transport method that can be incorporated into an existing radiation-hydrodynamics code for modeling ICF implosions. A novel time-dependent neutron transport method, based on the integral form of the neutron transport equation, was developed. This method utilizes a dimensionless integration space and the Neumann series method to obtain the integral form of the reduced collisions equations. This neutron transport method was implemented for infinite slab and sphere geometries. Using a pulsed source in space and time, the method was used to reproduce benchmark solutions previously published in the literature, and was found to have excellent agreement with these benchmarks. The method was expanded to incorporate finite slab and sphere geometries. The method was implemented for a finite slab, and benchmarked against PARTISN, a finite difference, discrete-ordinates code. The method was found to agree with PARTISN at intermediate mean free times, while diverging from PARTISN at late mean free times. The method was used to obtain analytic expression for the first two collided fluxes in a finite sphere geometry. A collision study was performed for both geometries to determine how many collisions were necessary to approximate the total flux at early mean free times. This study showed that only a few collisions were necessary to approximate the total flux at times of interest to ICF applications.

  10. Regulation of glomerulotubular balance. III. Implication of cytosolic calcium in flow-dependent proximal tubule transport.

    PubMed

    Du, Zhaopeng; Weinbaum, Sheldon; Weinstein, Alan M; Wang, Tong

    2015-04-15

    In the proximal tubule, axial flow (drag on brush-border microvilli) stimulates Na(+) and HCO3 (-) reabsorption by modulating both Na/H exchanger 3 (NHE3) and H-ATPase activity, a process critical to glomerulotubular balance. We have also demonstrated that blocking the angiotensin II receptor decreases baseline transport, but preserves the flow effect; dopamine leaves baseline fluxes intact, but abrogates the flow effect. In the current work, we provide evidence implicating cytosolic calcium in flow-dependent transport. Mouse proximal tubules were microperfused in vitro at perfusion rates of 5 and 20 nl/min, and reabsorption of fluid (Jv) and HCO3 (-) (JHCO3) were measured. We examined the effect of high luminal Ca(2+) (5 mM), 0 mM Ca(2+), the Ca(2+) chelator BAPTA-AM, the inositol 1,4,5-trisphosphate (IP3) receptor antagonist 2-aminoethoxydiphenyl borate (2-APB), and the Ca-ATPase inhibitor thapsigargin. In control tubules, increasing perfusion rate from 5 to 20 nl/min increased Jv by 62% and JHCO3 by 104%. With respect to Na(+) reabsorption, high luminal Ca(2+) decreased transport at low flow, but preserved the flow-induced increase; low luminal Ca(2+) had little impact; both BAPTA and 2-APB had no effect on baseline flux, but abrogated the flow effect; thapsigargin decreased baseline flow, leaving the flow effect intact. With respect to HCO3 (-) reabsorption, high luminal Ca(2+) decreased transport at low flow and mildly diminished the flow-induced increase; low luminal Ca(2+) had little impact; both BAPTA and 2-APB had no effect on baseline flux, but abrogated the flow effect. These data implicate IP3 receptor-mediated intracellular Ca(2+) signaling as a critical step in transduction of microvillous drag to modulate Na(+) and HCO3 (-) transport. PMID:25651568

  11. Spin Dependent Transport in Si/SiGe Few-Electron Quantum Dots

    NASA Astrophysics Data System (ADS)

    Simmons, Christie

    2008-03-01

    Si/SiGe quantum dots are of interest for quantum information processing due in large part to the existence of spin zero isotopes of both Si and Ge. We present the results of transport measurements and integrated charge sensing in silicon double and single quantum dots.[1,2] We observe two effects arising from spin dependent transport in a double quantum dot. First, and as expected, for one direction of current flow we observe spin blockade -- the canonical example of spin-to-charge conversion in transport. In addition, when current flow is reversed, we observe a second effect: strong tails of current extend from the sharp triangular regions in which current conventionally is observed. The presence of these tails is explained by a combination of long spin relaxation times and preferential loading of an excited spin state. We also present charge-sensing measurements of single and double quantum dots using an integrated quantum point contact. The charge sensor signal from single electron tunneling is well correlated with conventional transport through the system. When the tunnel barriers are large and transport through the dot is not measurable, charge sensing remains a viable means to track charge transitions and is used to confirm individual-electron occupation in a single quantum dot. Work performed in collaboration with Nakul Shaji, Madhu Thalakulam, Levente J. Klein, H. Luo, Hua Qin, R. H. Blick, D. E. Savage, M. G. Lagally, A. J. Rimberg, R. Joynt, M. Friesen, S. N. Coppersmith, M. A. Eriksson. Work supported by ARO, LPS, NSF and DOE. (1) Shaji, N. et al. e-print arXiv:0708.0794 (2) Simmons, C. B. et al. Appl. Phys. Lett. 91, 213103 (2007).

  12. Glucose-dependent glucose transporter 1 expression and its impact on viability of thyroid cancer cells.

    PubMed

    Jó?wiak, Pawe?; Krze?lak, Anna; Bry?, Magdalena; Lipi?ska, Anna

    2015-02-01

    Cancer cells exhibit an altered metabolism characterized by enhanced glycolysis and glucose consumption. In glucose?addicted cancer cells upregulation of glucose transport across the plasma membrane is mediated by a family of facilitated glucose transporter proteins, particularly glucose transporter 1 (GLUT1). The aim of the present study was to investigate the impact of GLUT1 expression on glucose uptake and viability of FTC-133 and 8305c thyroid cancer cells growing in hypoglycemic, normoglycemic and hyperglycemic conditions. The results showed that the total expression of GLUT1 was higher in the two cell types growing in low glucose compared to cells growing in normoglycemia or hyperglycemia and this was correlated with AKT Ser473 phosphorylation but not with the expression of hypoxia inducible factor ? (HIF1?). However, the membrane expression of GLUT1 was correlated with HIF1? expression. HIF1? expression was positively correlated with the glucose concentration in FTC-133 cells, whereas this expression was inversely correlated in 8305c cells. Glucose uptake was dependent on the membrane level of GLUT1 but not total GLUT1 expression. Downregulation of GLUT1 expression by RNAi in FTC-133 cells caused a reduction in glucose uptake but did not significantly affect cell viability. In the case of 8305c cells showing low endogenous GLUT1 expression and lack of HIF1? expression in normoxic conditions GLUT1 RNAi impacted cell viability. These data suggested that GLUT1 may be part of an AKT1-dependent mechanism allowing cells to survive in low levels of glucose. Glucose concentration inversely affected HIF1? expression and the level of GLUT1 in membrane as well as glucose uptake in FTC-133 and 8305c cells. The extent of GLUT1 impact on cell viability was also cell-type-dependent. PMID:25502934

  13. NHERF1 Regulation of PTH-dependent Bimodal Pi Transport in Osteoblasts

    PubMed Central

    Wang, Bin; Yang, Yanmei; Liu, Li; Blair, Harry C.; Friedman, Peter A.

    2012-01-01

    Control of systemic inorganic phosphate (Pi) levels is crucial for osteoid mineralization. Parathyroid hormone (PTH) mediates actions on phosphate homeostasis mostly by regulating the activity of the type 2 sodium-phosphate cotransporter (Npt2), and this action requires the PDZ protein NHERF1. Osteoblasts express Npt2 and in response to PTH enhance osteogenesis by increasing mineralized matrix. The regulation of Pi transport in osteoblasts is poorly understood. To address this gap we characterized PTH-dependent Pi transport and the role of NHERF1 in primary mouse calvarial osteoblasts. Under proliferating conditions osteoblasts express Npt2a, Npt2b, PTH receptor, and NHERF1. Npt2a mRNA expression was lower in calvarial osteoblasts from NHERF1-null mice. Under basal conditions Pi uptake in osteoblasts from wild-type mice was greater than that of knockout mice. PTH inhibited Pi uptake in proliferating osteoblasts from wild-type mice, but not in cells from knockout mice. In vitro induction of mineralization enhanced osteoblast differentiation and increased osterix and osteocalcin expression. Contrary to the results with proliferating osteoblasts, PTH increased Pi uptake and ATP secretion in differentiated osteoblasts from wild-type mice. PTH had no effect on Pi uptake or ATP release in differentiated osteoblasts from knockout mice. NHERF1 regulation of PTH-sensitive Pi uptake in proliferating osteoblasts is mediated by cAMP/PKA and PLC/PKC, while modulation of Pi uptake in differentiated osteoblasts depends only on cAMP/PKA signaling. The results suggest that NHERF1 cooperates with PTH in differentiated osteoblasts to increase matrix mineralization. We conclude that NHERF1 regulates PTH differentially affects Na-dependent Pi transport at distinct stages of osteoblast proliferation and maturation. PMID:23046970

  14. A time-dependent momentum-space density functional theoretical approach for electron transport dynamics in molecular devices

    E-print Network

    Chu, Shih-I; Zhou, Zhongyuan

    2009-10-27

    We propose a time-dependent density functional theoretical (TDDFT) approach in momentum (\\mathcal{P} ) space for the study of electron transport in molecular devices under arbitrary biases. The basic equation of motion, which is a time...

  15. Synthesis of a rabbit polyclonal antibody to the human sodium-dependent multivitamin transporter.

    PubMed

    Griffin, Jacob B; Stanley, J Steven; Zempleni, Janos

    2002-07-01

    In mammalian cells, biotin is covalently attached to carboxylases and histones and is required for cell proliferation and function. Cellular uptake of biotin (as well as pantothenic acid and lipoic acid) is mediated by the sodium-dependent multivitamin transporter, SMVT. Studies of cellular biotin homeostasis have been hampered by the lack of an antibody to SMVT. Here, we describe the synthesis of a rabbit polyclonal antibody to human SMVT. Using this antibody, SMVT has been identified in human peripheral blood mononuclear cells, Caco-2 cells, and HepG2 cells. Moreover, we observed that cells respond to proliferation with increased synthesis of SMVT. PMID:12214555

  16. Molecular size of a Na sup + -dependent amino acid transporter in Ehrlich ascites cell plasma membranes estimated by radiation inactivation

    Microsoft Academic Search

    John I. McCormick; R. M. Johnstone; M. Jette; Richard Beliveau; M. Potier

    1991-01-01

    Radiation inactivation was used to estimate the molecular size of a Na{sup +}-dependent amino acid transport system in Ehrlich ascites cell plasma membrane vesicles. Na{sup +}-dependent α-aminoisobutyric acid uptake was measured after membranes were irradiated at -78.5C in a cryoprotective medium. Twenty-five percent of the transport activity was lost at low radiation doses (<0.5 Mrad), suggesting the presence of a

  17. A hybrid transport-diffusion Monte Carlo method for frequency-dependent radiative-transfer simulations

    SciTech Connect

    Densmore, Jeffery D., E-mail: jdd@lanl.gov [Computational Physics and Methods Group, Los Alamos National Laboratory, P.O. Box 1663, MS D409, Los Alamos, NM 87545 (United States); Thompson, Kelly G., E-mail: kgt@lanl.gov [Computational Physics and Methods Group, Los Alamos National Laboratory, P.O. Box 1663, MS D409, Los Alamos, NM 87545 (United States); Urbatsch, Todd J., E-mail: tmonster@lanl.gov [Computational Physics and Methods Group, Los Alamos National Laboratory, P.O. Box 1663, MS D409, Los Alamos, NM 87545 (United States)

    2012-08-15

    Discrete Diffusion Monte Carlo (DDMC) is a technique for increasing the efficiency of Implicit Monte Carlo radiative-transfer simulations in optically thick media. In DDMC, particles take discrete steps between spatial cells according to a discretized diffusion equation. Each discrete step replaces many smaller Monte Carlo steps, thus improving the efficiency of the simulation. In this paper, we present an extension of DDMC for frequency-dependent radiative transfer. We base our new DDMC method on a frequency-integrated diffusion equation for frequencies below a specified threshold, as optical thickness is typically a decreasing function of frequency. Above this threshold we employ standard Monte Carlo, which results in a hybrid transport-diffusion scheme. With a set of frequency-dependent test problems, we confirm the accuracy and increased efficiency of our new DDMC method.

  18. Time-dependent electron transport through an Aharonov Bohm ring embedded with two quantum dots

    NASA Astrophysics Data System (ADS)

    Pan, Hui; Zhao, Li-Na; Lü, Rong

    2008-08-01

    The time-dependent electron transport through an Aharonov-Bohm ring embedded with two quantum dots in the presence of external microwave (MW) fields are investigated theoretically by using the nonequilibrium Green's function method. Whether the MW field can induce or suppress the Fano resonance depends on the part to which the field is applied. When the MW field is applied only to the two quantum dots, the photon-assisted Fano peaks appear at the sidebands of the original Fano peak. The existence of the original Fano peak or the photon-assisted ones can be controlled by the field strength. When the MW field is applied only to one lead, the original Fano peak is suppressed by the MW field, and the negative current caused by the electron-photon pump effects is found.

  19. Azimuthally Anisotropic 3D Velocity Continuation

    DOE PAGESBeta

    Burnett, William; Fomel, Sergey

    2011-01-01

    We extend time-domain velocity continuation to the zero-offset 3D azimuthally anisotropic case. Velocity continuation describes how a seismic image changes given a change in migration velocity. This description turns out to be of a wave propagation process, in which images change along a velocity axis. In the anisotropic case, the velocity model is multiparameter. Therefore, anisotropic image propagation is multidimensional. We use a three-parameter slowness model, which is related to azimuthal variations in velocity, as well as their principal directions. This information is useful for fracture and reservoir characterization from seismic data. We provide synthetic diffraction imaging examples to illustratemore »the concept and potential applications of azimuthal velocity continuation and to analyze the impulse response of the 3D velocity continuation operator.« less

  20. Modulation of ileal apical Na+-dependent bile acid transporter ASBT by protein kinase C

    PubMed Central

    Sarwar, Zaheer; Annaba, Fadi; Dwivedi, Alka; Saksena, Seema; Gill, Ravinder K.; Alrefai, Waddah A.

    2009-01-01

    Ileal apical Na+-dependent bile acid transporter (ASBT) is responsible for reabsorbing the majority of bile acids from the intestinal lumen. Rapid adaptation of ASBT function in response to physiological and pathophysiological stimuli is essential for the maintenance of bile acid homeostasis. However, not much is known about molecular mechanisms responsible for acute posttranscriptional regulation of ileal ASBT. The protein kinase C (PKC)-dependent pathway represents a major cell signaling mechanism influencing intestinal epithelial functions. The present studies were, therefore, undertaken to investigate ASBT regulation in intestinal Caco-2 monolayers by the well-known PKC activator phorbol 12-myristate 13-acetate (PMA). Our results showed that Na+-dependent [3H]taurocholic acid uptake in Caco-2 cells was significantly inhibited in response to 2 h incubation with 100 nM PMA compared with incubation with 4?-PMA (inactive form). The inhibitory effect of PMA was blocked in the presence of 5 ?M bisindolylmaleimide I (PKC inhibitor) but not 1,2-bis(2-aminophenoxy)ethane-N,N,N?,N?-tetraacetic acid-AM (Ca2+ chelator) or LY-294002 (phosphatidylinositol 3-kinase inhibitor). PMA inhibition of ASBT function was also abrogated in the presence of myristoylated PKC? pseudosubstrate peptide, indicating involvement of the atypical PKC? isoform. The inhibition by PMA was associated with a significant decrease in the maximal velocity of the transporter and a reduction in ASBT plasma membrane content, suggesting a modulation by vesicular recycling. Our novel findings demonstrate a posttranscriptional modulation of ileal ASBT function and membrane expression by phorbol ester via a PKC?-dependent pathway. PMID:19571234

  1. Charge-dependent transport switching of single molecular ions in a weak polyelectrolyte multilayer.

    PubMed

    Tauzin, Lawrence J; Shuang, Bo; Kisley, Lydia; Mansur, Andrea P; Chen, Jixin; de Leon, Al; Advincula, Rigoberto C; Landes, Christy F

    2014-07-22

    The tunable nature of weak polyelectrolyte multilayers makes them ideal candidates for drug loading and delivery, water filtration, and separations, yet the lateral transport of charged molecules in these systems remains largely unexplored at the single molecule level. We report the direct measurement of the charge-dependent, pH-tunable, multimodal interaction of single charged molecules with a weak polyelectrolyte multilayer thin film, a 10 bilayer film of poly(acrylic acid) and poly(allylamine hydrochloride) PAA/PAH. Using fluorescence microscopy and single-molecule tracking, two modes of interaction were detected: (1) adsorption, characterized by the molecule remaining immobilized in a subresolution region and (2) diffusion trajectories characteristic of hopping (D ? 10(-9) cm(2)/s). Radius of gyration evolution analysis and comparison with simulated trajectories confirmed the coexistence of the two transport modes in the same single molecule trajectories. A mechanistic explanation for the probe and condition mediated dynamics is proposed based on a combination of electrostatics and a reversible, pH-induced alteration of the nanoscopic structure of the film. Our results are in good agreement with ensemble studies conducted on similar films, confirm a previously-unobserved hopping mechanism for charged molecules in polyelectrolyte multilayers, and demonstrate that single molecule spectroscopy can offer mechanistic insight into the role of electrostatics and nanoscale tunability of transport in weak polyelectrolyte multilayers. PMID:24960617

  2. Conformational Dependence of Charge Transport and Band Gap in Poly (3-Hexyl Thiophene) Oligomers

    NASA Astrophysics Data System (ADS)

    Bhatta, Ram; Yimer, Yeneneh; Tsige, Mesfin; Perry, David

    2011-04-01

    Structural defects will affect the charge transport properties and the band gap in the Poly (3-Hexylthiophene) (P3HT) polymer, a promising electron donor for organic solar cells. In the present work, such effects are modeled by density functional theory (DFT) calculations on P3HT oligomers up to 12 monomer units in planar and non-planar conformations. DFT calculations were performed at B3LYP/6-31++G(d,p) treating both backbone and hexyl chains explicitly. The structural properties of the oligomers change significantly for 2 to 8 unit isolated oligomers but reach asymptotic values by a 10 unit P3HT chain. The dependence of charge transfer integral on chain length and on the backbone torsional angle is reported. The band gap approaches ˜2.0 eV asymptotically as the chain length is increased, which is close to the experimental value. Comparison of the charge transport integral for P3HT with polythiophene (PT) shows that the hexyl chains enhance electronic coupling across the P3HT chain. The charge transport integral declines exponentially as the oligomers are lengthened with a half-length of 4.4 units.

  3. Mechanistic studies of the apical sodium-dependent bile acid transporter.

    PubMed

    Alhadeff, Raphael; Ganoth, Assaf; Arkin, Isaiah T

    2015-06-01

    In mammals, the apical sodium-dependent bile acid transporter (ASBT) is responsible for the reuptake of bile acid from the intestine, thus recycling bile acid that is secreted from the gallbladder, for the purpose of digestion. As bile acid is synthesized from cholesterol, ASBT inhibition could have important implications in regulation of cholesterol levels in the blood. We report on a simulation study of the recently resolved structures of the inward-facing ASBT from Neisseria meningitidis and from Yersinia frederiksenii, as well as of an ASBT variant from Yersinia frederiksenii suggested to be in the outward-facing conformation. Classical and steered atomistic simulations and comprehensive potential of mean force analyses of ASBT, both in the absence and presence of ions and substrate, allow us to characterize and gain structural insights into the Na(+) binding sites and propose a mechanistic model for the transport cycle. In particular, we investigate structural features of the ion translocation pathway, and suggest a third putative Na(+) binding site. Our study sheds light on the structure-function relationship of bacterial ASBT and may promote a deeper understanding of transport mechanism altogether. Proteins 2015; 83:1107-1117. © 2015 Wiley Periodicals, Inc. PMID:25820648

  4. Molecular mechanism of pH-dependent substrate transport by an arginine-agmatine antiporter.

    PubMed

    Wang, Sheng; Yan, Renhong; Zhang, Xi; Chu, Qi; Shi, Yigong

    2014-09-01

    Enteropathogenic bacteria, exemplified by Escherichia coli, rely on acid-resistance systems (ARs) to survive the acidic environment of the stomach. AR3 consumes intracellular protons through decarboxylation of arginine (Arg) in the cytoplasm and exchange of the reaction product agmatine (Agm) with extracellular Arg. The latter process is mediated by the Arg:Agm antiporter AdiC, which is activated in response to acidic pH and remains fully active at pH 6.0 and below. Despite our knowledge of structural information, the molecular mechanism by which AdiC senses acidic pH remains completely unknown. Relying on alanine-scanning mutagenesis and an in vitro proteoliposome-based transport assay, we have identified Tyr74 as a critical pH sensor in AdiC. The AdiC variant Y74A exhibited robust transport activity at all pH values examined while maintaining stringent substrate specificity for Arg:Agm. Replacement of Tyr74 by Phe, but not by any other amino acid, led to the maintenance of pH-dependent substrate transport. These observations, in conjunction with structural information, identify a working model for pH-induced activation of AdiC in which a closed conformation is disrupted by cation-? interactions between proton and the aromatic side chain of Tyr74. PMID:25136114

  5. Dijet azimuthal decorrelations for $\\Delta \\phi_{\\rm dijet} pi/3$ in perturbative QCD

    E-print Network

    Wobisch, M

    2015-01-01

    We point out an inconsistency in perturbative QCD predictions previously used for dijet azimuthal decorrelations for azimuthal angles of $\\Delta\\phi_{\\rm dijet} pi/3$ between the two jets. We show how the inconsistency arises and how the calculations can be modified to provide more accurate results that exhibit a smaller scale dependence and give a better description of the data than the inconsistent results. We also explain how the quality of the predictions strongly depends on a perceivedly minor detail in the definition of the dijet phase space and give recommendations for future measurements.

  6. pH-dependent transport of metal cations in porous media.

    PubMed

    Prigiobbe, Valentina; Bryant, Steven L

    2014-04-01

    We study the effect of pH-dependent adsorption and hydrodynamic dispersion on cation transport through a reactive porous medium with a hydrophilic surface. We investigate how competitive adsorption between a proton and a metal (which in some situations of practical interest may also be a radionuclide) can facilitate the migration of a certain fraction of the latter. We performed laboratory experiments using a chromatographic column filled with silica beads coated with iron oxide and flooded initially with an acidic solution (pH ? 3) and then with an alkaline solution (pH > 7) containing either sodium, potassium, lithium, calcium, magnesium, or barium. The composition of each injected solution was chosen to represent one of two possible theoretical predictions, either a retarded shock and a fast pulse, that is, traveling at the interstitial fluid velocity, or only a retarded shock. Highly resolved breakthrough curves measured with inline ion chromatography allowed us to observe in all cases agreement with theoretical predictions, including numerous observations of a fast pulse. The fast pulse is the result of the interaction between pH-dependent adsorption and hydrodynamic dispersion and has previously been observed in systems with strontium. Here, we show the fast pulse arises also in the case of other cations allowing a generalization of the physical mechanism underlying this phenomenon and consideration of it as a new fast transport behavior. A one-dimensional reactive transport model for an incompressible fluid was developed combining surface complexation with mass conservation equations for a solute and the acidity (difference between the total proton and hydroxide concentration). In all cases, the model agrees with the measurements capturing the underlying physics of the overall transport behavior. Our results suggest that the interplay between pH-dependent adsorption and hydrodynamic dispersion can give rise to the rapid migration of metals through reactive porous media with potential effects on, for example, the performance of subsurface engineering infrastructures for pollutant containment, the mobilization of metal contaminants by brine acidified upon contact with CO2 during geologic carbon storage, and the chromatographic separation processes in industrial applications. PMID:24564735

  7. Transport of Solutes in Hyporheic Zones with Temperature-Dependent Reversible Sorption

    NASA Astrophysics Data System (ADS)

    Kaufman, M.; Cardenas, M. B.; Zheng, L.

    2014-12-01

    One of the most important processes impacting the mobility of heavy metals in rivers and their hyporheic zones is reversible sorption to sediment. Reversible sorption has been shown to be a temperature dependent process, however the impact of this variability on heavy metal fate and transport, as well as environmental metal concentrations, has not received much attention. In this study we used zinc as an example heavy metal. Previous studies of the impact of temperature on the sorption of zinc on a goethite substrate show a change in partitioning coefficient and thus retardation factor of 10 to over 60 percent with a temperature change from 10 to 25*C, depending on concentration of dissolved zinc in the water. This relationship was extrapolated to estimate the change in reversible sorption of zinc on silicate sand. This change was then utilized within a finite-element model coupling hyporheic fluid flow in porous media with heat transfer and solute transport with reversible sorption to explore the ways in which variations in surface water temperature over varying timescales can drive changes in both zinc sorption and dissolved zinc fluxes at the bedform scale. These linked processes are of fundamental importance when considering the number of different ways in which surface water temperatures can be varied through both human and non-human activities.

  8. Biogenesis of the crystalloid organelle in Plasmodium involves microtubule-dependent vesicle transport and assembly.

    PubMed

    Saeed, Sadia; Tremp, Annie Z; Dessens, Johannes T

    2015-07-01

    Malaria parasites possess unique subcellular structures and organelles. One of these is the crystalloid, a multivesicular organelle that forms during the parasite's development in vector mosquitoes. The formation and function of these organelles remain poorly understood. A family of six conserved and modular proteins named LCCL-lectin adhesive-like proteins (LAPs), which have essential roles in sporozoite transmission, localise to the crystalloids. In this study we analyse crystalloid formation using transgenic Plasmodium berghei parasites expressing GFP-tagged LAP3. We show that deletion of the LCCL domain from LAP3 causes retarded crystalloid development, while knockout of LAP3 prevents formation of the organelle. Our data reveal that the process of crystalloid formation involves active relocation of endoplasmic reticulum-derived vesicles to common assembly points via microtubule-dependent transport. Inhibition of microtubule-dependent cargo transport disrupts this process and replicates the LCCL domain deletion mutant phenotype in wildtype parasites. These findings provide the first clear insight into crystalloid biogenesis, demonstrating a fundamental role for the LAP family in this process, and identifying the crystalloid and its formation as potential targets for malaria transmission control. PMID:25900212

  9. Biogenesis of the crystalloid organelle in Plasmodium involves microtubule-dependent vesicle transport and assembly

    PubMed Central

    Saeed, Sadia; Tremp, Annie Z.; Dessens, Johannes T.

    2015-01-01

    Malaria parasites possess unique subcellular structures and organelles. One of these is the crystalloid, a multivesicular organelle that forms during the parasite’s development in vector mosquitoes. The formation and function of these organelles remain poorly understood. A family of six conserved and modular proteins named LCCL-lectin adhesive-like proteins (LAPs), which have essential roles in sporozoite transmission, localise to the crystalloids. In this study we analyse crystalloid formation using transgenic Plasmodium berghei parasites expressing GFP-tagged LAP3. We show that deletion of the LCCL domain from LAP3 causes retarded crystalloid development, while knockout of LAP3 prevents formation of the organelle. Our data reveal that the process of crystalloid formation involves active relocation of endoplasmic reticulum-derived vesicles to common assembly points via microtubule-dependent transport. Inhibition of microtubule-dependent cargo transport disrupts this process and replicates the LCCL domain deletion mutant phenotype in wildtype parasites. These findings provide the first clear insight into crystalloid biogenesis, demonstrating a fundamental role for the LAP family in this process, and identifying the crystalloid and its formation as potential targets for malaria transmission control. PMID:25900212

  10. Spin-dependent transport for armchair-edge graphene nanoribbons between ferromagnetic leads

    NASA Astrophysics Data System (ADS)

    Zhou, Benhu; Chen, Xiongwen; Zhou, Benliang; Ding, Kai-He; Zhou, Guanghui

    2011-04-01

    We theoretically investigate the spin-dependent transport for the system of an armchair-edge graphene nanoribbon (AGNR) between two ferromagnetic (FM) leads with arbitrary polarization directions at low temperatures, where a magnetic insulator is deposited on the AGNR to induce an exchange splitting between spin-up and -down carriers. By using the standard nonequilibrium Green's function (NGF) technique, it is demonstrated that the spin-resolved transport property for the system depends sensitively on both the width of AGNR and the polarization strength of FM leads. The tunneling magnetoresistance (TMR) around zero bias voltage possesses a pronounced plateau structure for a system with semiconducting 7-AGNR or metallic 8-AGNR in the absence of exchange splitting, but this plateau structure for the 8-AGNR system is remarkably broader than that for the 7-AGNR one. Interestingly, an increase of the exchange splitting ? suppresses the amplitude of the structure for the 7-AGNR system. However, the TMR is much enhanced for the 8-AGNR system under a bias amplitude comparable to the splitting strength. Further, the current-induced spin-transfer torque (STT) for the 7-AGNR system is systematically larger than that for the 8-AGNR one. The findings here suggest the design of GNR-based spintronic devices by using a metallic AGNR, but it is more favorable to fabricate a current-controlled magnetic memory element by using a semiconducting AGNR.

  11. Temperature Dependent Transport of Two-Dimensional Electrons in the Integral Quantum Hall Regime.

    NASA Astrophysics Data System (ADS)

    Wei, Hsuang-Ping

    This thesis is concerned with the temperature (T) dependent electronic transport properties of a two dimensional electron gas subject to background potential fluctuations and a perpendicular magnetic field. We have carried out an extensive temperature dependent study of the transport coefficients, in the region of an integral quantum plateau, in an In(,x)Ga(,1-x)As/InP heterostructure for 4.2K < T < 50K. By assuming a simple thermal activation picture, we demonstrate a quantitative deduction of the electron density of states. Our results indicate that there exists a significant number of states (1 x 10('10)cm(' -2)meV('-1)) even at the middle between two Landau levels, which is unexpected from model calculations based on short ranged randomness. In addition, the different T dependent behavior of (rho)(,xx) between the states in the tails and those near the center of a Landau level, indicates the existence of different electron states in a Landau level. Moreover, we have performed T dependent trans- port measurements in the transition region between two quantum plateaus, in several different materials. In the In(,x)Ga(,1-x)As/InP sample, when T(, )> 4K, the transport behavior can be attributed to the T dependent distribution function. When T(, )< 4K, our experi- mental T-driven (sigma)(,xx) vs. (sigma)(,xy) flow diagram is consistent with the pre- dicted theoretical renormalization group flow diagram, and suggests the existence of a critical point related to the localization to delocali- zation transition. However, in the GaAs/Al(,x)Ga(,1-x)As samples there is a difference in the T dependent behavior of (sigma)(,xx), between N = 1(UPARR) and 1(DARR) electrons. First, (sigma)(,xx)(1(UPARR)) decreases with decreasing T; whereas (sigma)(,xx)(1(DARR)) increases with decreasing T for 0.3K(, )< T < 4.2K. Second, (sigma)(,xx)('max) (1(DARR)) ('(TURN)) 3(sigma)(,xx)('max) (1(UPARR)) at T('(TURN))0.5K in all of our samples. These results indicate the existence of spin dependent scattering in GaAs/ Al(,x)Ga(,1-x)As sample. Furthermore the (sigma)(,xx)('max) value in our GaAs/ Al(,x)Ga(,1-x)As samples is found to be smaller than 30% of the value calculated from SCBA, at T('(TURN))4.2K. Finally, in the weak localization regime (B('(TURN))0), our magneto-transport data, in a GaAs/Al(,x)Ga(,1 -x)As sample with a split gate on top, is consistent with 1D localization theory. The extracted l(,in) as a function of (sigma) supports the theory for electron-electron scattering in a weakly disordered system.

  12. Azimuthal Emission Patterns of $K^{+}$ and of $ K^{-} $ Mesons in Ni + Ni Collisions near the Strangeness Production Threshold

    E-print Network

    V. Zinyuk; T. I. Kang; Y. Leifels; N. Herrmann; B. Hong; R. Averbeck; A. Andronic; V. Barret; Z. Basrak; N. Bastid; M. L. Benabderrahmane; M. Berger; P. Buehler; M. Cargnelli; R. ?aplar; I. Carevic; P. Crochet; I. Deppner; P. Dupieux; M. Dželalija; L. Fabbietti; Z. Fodor; P. Gasik; I. Gašpari?; Y. Grishkin; O. N. Hartmann; K. D. Hildenbrand; J. Kecskemeti; Y. J. Kim; M. Kirejczyk; M. Kiš; P. Koczon; R. Kotte; A. Lebedev; A. Le Fèvre; J. L. Liu; X. Lopez; V. Manko; J. Marton; T. Matulewicz; R. Münzer; M. Petrovici; K. Piasecki; F. Rami; A. Reischl; W. Reisdorf; M. S. Ryu; P. Schmidt; A. Schüttauf; Z. Seres; B. Sikora; K. S. Sim; V. Simion; K. Siwek- ilczy?ska; V. Smolyankin; K. Suzuki; Z. Tyminski; P. Wagner; E. Widmann; K. Wi?niewski; Z. G. Xiao; I. Yushmanov; Y. Zhang; A. Zhilin; J. Zmeskal

    2014-07-04

    Azimuthal emission patterns of $K^\\pm$ mesons have been measured in Ni + Ni collisions with the FOPI spectrometer at a beam kinetic energy of 1.91 A GeV. The transverse momentum $p_{T}$ integrated directed and elliptic flow of $K^{+}$ and $K^{-}$ mesons as well as the centrality dependence of $p_{T}$ - differential directed flow of $K^{+}$ mesons are compared to the predictions of HSD and IQMD transport models. The data exhibits different propagation patterns of $K^{+}$ and $K^{-}$ mesons in the compressed and heated nuclear medium and favor the existence of a kaon-nucleon in-medium potential, repulsive for $K^{+}$ mesons and attractive for $K^{-}$ mesons.

  13. Induction of Mrp3 and Mrp4 transporters during acetaminophen hepatotoxicity is dependent on Nrf2

    SciTech Connect

    Aleksunes, Lauren M. [Department of Pharmaceutical Sciences, School of Pharmacy, University of Connecticut, 69 North Eagleville Road, Unit 3092, Storrs, CT 06269-3092 (United States); Department of Pharmacology, Toxicology and Therapeutics, University of Kansas Medical Center, Kansas City, KS (United States)], E-mail: laleksunes@kumc.edu; Slitt, Angela L. [Department of Pharmacology, Toxicology and Therapeutics, University of Kansas Medical Center, Kansas City, KS (United States)], E-mail: aslitt@etal.uri.edu; Maher, Jonathan M. [Department of Pharmacology, Toxicology and Therapeutics, University of Kansas Medical Center, Kansas City, KS (United States)], E-mail: jmaher@tara.tsukuba.ac.jp; Augustine, Lisa M. [Department of Pharmacology and Toxicology, University of Arizona, Tucson, AZ (United States)], E-mail: bird@pharmacy.arizona.edu; Goedken, Michael J. [Department of Pharmaceutical Sciences, School of Pharmacy, University of Connecticut, 69 North Eagleville Road, Unit 3092, Storrs, CT 06269-3092 (United States)], E-mail: michael.goedken@gmail.com; Chan, Jefferson Y. [Department of Pathology, University of California, Irvine, CA (United States)], E-mail: jchan@uci.edu; Cherrington, Nathan J. [Department of Pharmacology and Toxicology, University of Arizona, Tucson, AZ (United States)], E-mail: cherrington@pharmacy.arizona.edu; Klaassen, Curtis D. [Department of Pharmacology, Toxicology and Therapeutics, University of Kansas Medical Center, Kansas City, KS (United States)], E-mail: cklaasse@kumc.edu; Manautou, Jose E. [Department of Pharmaceutical Sciences, School of Pharmacy, University of Connecticut, 69 North Eagleville Road, Unit 3092, Storrs, CT 06269-3092 (United States)], E-mail: jose.manautou@uconn.edu

    2008-01-01

    The transcription factor NFE2-related factor 2 (Nrf2) mediates detoxification and antioxidant gene transcription following electrophile exposure and oxidative stress. Mice deficient in Nrf2 (Nrf2-null) are highly susceptible to acetaminophen (APAP) hepatotoxicity and exhibit lower basal and inducible expression of cytoprotective genes, including NADPH quinone oxidoreductase 1 (Nqo1) and glutamate cysteine ligase (catalytic subunit, or Gclc). Administration of toxic APAP doses to C57BL/6J mice generates electrophilic stress and subsequently increases levels of hepatic Nqo1, Gclc and the efflux multidrug resistance-associated protein transporters 1-4 (Mrp1-4). It was hypothesized that induction of hepatic Mrp1-4 expression following APAP is Nrf2 dependent. Plasma and livers from wild-type (WT) and Nrf2-null mice were collected 4, 24 and 48 h after APAP. As expected, hepatotoxicity was greater in Nrf2-null compared to WT mice. Gene and protein expression of Mrp1-4 and the Nrf2 targets, Nqo1 and Gclc, was measured. Induction of Nqo1 and Gclc mRNA and protein after APAP was dependent on Nrf2 expression. Similarly, APAP treatment increased hepatic Mrp3 and Mrp4 mRNA and protein in WT, but not Nrf2-null mice. Mrp1 was induced in both genotypes after APAP, suggesting that elevated expression of this transporter was independent of Nrf2. Mrp2 was not induced in either genotype at the mRNA or protein levels. These results show that Nrf2 mediates induction of Mrp3 and Mrp4 after APAP but does not affect Mrp1 or Mrp2. Thus coordinated regulation of detoxification enzymes and transporters by Nrf2 during APAP hepatotoxicity is a mechanism by which hepatocytes may limit intracellular accumulation of potentially toxic chemicals.

  14. Length dependence of electron transport through molecular wires--a first principles perspective.

    PubMed

    Khoo, Khoong Hong; Chen, Yifeng; Li, Suchun; Quek, Su Ying

    2015-01-01

    One-dimensional wires constitute a fundamental building block in nanoscale electronics. However, truly one-dimensional metallic wires do not exist due to Peierls distortion. Molecular wires come close to being stable one-dimensional wires, but are typically semiconductors, with charge transport occurring via tunneling or thermally-activated hopping. In this review, we discuss electron transport through molecular wires, from a theoretical, quantum mechanical perspective based on first principles. We focus specifically on the off-resonant tunneling regime, applicable to shorter molecular wires (transport. Here, conductance decays exponentially with the wire length, with an exponential decay constant, beta, that is independent of temperature. Different levels of first principles theory are discussed, starting with the computational workhorse - density functional theory (DFT), and moving on to many-electron GW methods as well as GW-inspired DFT + Sigma calculations. These different levels of theory are applied in two major computational frameworks - complex band structure (CBS) calculations to estimate the tunneling decay constant, beta, and Landauer-Buttiker transport calculations that consider explicitly the effects of contact geometry, and compute the transmission spectra directly. In general, for the same level of theory, the Landauer-Buttiker calculations give more quantitative values of beta than the CBS calculations. However, the CBS calculations have a long history and are particularly useful for quick estimates of beta. Comparing different levels of theory, it is clear that GW and DFT + Sigma calculations give significantly improved agreement with experiment compared to DFT, especially for the conductance values. Quantitative agreement can also be obtained for the Seebeck coefficient - another independent probe of electron transport. This excellent agreement provides confirmative evidence of off-resonant tunneling in the systems under investigation. Calculations show that the tunneling decay constant beta is a robust quantity that does not depend on details of the contact geometry, provided that the same contact geometry is used for all molecular lengths considered. However, because conductance is sensitive to contact geometry, values of beta obtained by considering conductance values where the contact geometry is changing with the molecular junction length can be quite different. Experimentally measured values of beta in general compare well with beta obtained using DFT + Sigma and GW transport calculations, while discrepancies can be attributed to changes in the experimental contact geometries with molecular length. This review also summarizes experimental and theoretical efforts towards finding perfect molecular wires with high conductance and small beta values. PMID:25407785

  15. Glucose deprivation increases monocarboxylate transporter 1 (MCT1) expression and MCT1-dependent tumor cell migration.

    PubMed

    De Saedeleer, C J; Porporato, P E; Copetti, T; Pérez-Escuredo, J; Payen, V L; Brisson, L; Feron, O; Sonveaux, P

    2014-07-31

    The glycolytic end-product lactate is a pleiotropic tumor growth-promoting factor. Its activities primarily depend on its uptake, a process facilitated by the lactate-proton symporter monocarboxylate transporter 1 (MCT1). Therefore, targeting the transporter or its chaperon protein CD147/basigin, itself involved in the aggressive malignant phenotype, is an attractive therapeutic option for cancer, but basic information is still lacking regarding the regulation of the expression, interaction and activities of both proteins. In this study, we found that glucose deprivation dose-dependently upregulates MCT1 and CD147 protein expression and their interaction in oxidative tumor cells. While this posttranslational induction could be recapitulated using glycolysis inhibition, hypoxia, oxidative phosphorylation (OXPHOS) inhibitor rotenone or hydrogen peroxide, it was blocked with alternative oxidative substrates and specific antioxidants, pointing out at a mitochondrial control. Indeed, we found that the stabilization of MCT1 and CD147 proteins upon glucose removal depends on mitochondrial impairment and the associated generation of reactive oxygen species. When glucose was a limited resource (a situation occurring naturally or during the treatment of many tumors), MCT1-CD147 heterocomplexes accumulated, including in cell protrusions of the plasma membrane. It endowed oxidative tumor cells with increased migratory capacities towards glucose. Migration increased in cells overexpressing MCT1 and CD147, but it was inhibited in glucose-starved cells provided with an alternative oxidative fuel, treated with an antioxidant, lacking MCT1 expression, or submitted to pharmacological MCT1 inhibition. While our study identifies the mitochondrion as a glucose sensor promoting tumor cell migration, MCT1 is also revealed as a transducer of this response, providing a new rationale for the use of MCT1 inhibitors in cancer. PMID:24166504

  16. The Dependence of H-mode Energy Confinement and Transport on Collisionality in NSTX

    SciTech Connect

    Kaye, S. M.; Gerhardt, S.; Guttenfelder, W.; Maingi, R.; Bell, R. E.; Diallo, A.; LeBlanc, B. P.; Podesta, M.

    2012-11-27

    Understanding the dependence of confi nement on collisionality in tokamaks is important for the design of next-step devices, which will operate at collisionalities at least one order of magnitude lower than in present generation. A wide range of collisionality has been obtained in the National Spherical Torus Experiment (NSTX) by employing two different wall conditioning techniques, one with boronization and between-shot helium glow discharge conditioning (HeGDC+B), and one using lithium evaporation (Li EVAP). Previous studies of HeGDC+B plasmas indicated a strong and favorable dependence of normalized con nement on collisionality. Discharges with lithium conditioning discussed in the present study gen- erally achieved lower collisionality, extending the accessible range of collisionality by almost an order of unity. While the confinement dependences on dimensional, engineering variables of the HeGDC+B and Li EVAP datasets differed, collisionality was found to unify the trends, with the lower collisionality lithium conditioned discharges extending the trend of increasing normalized confi nement time with decreasing collisionality when other dimension less variables were held as fi xed as possible. This increase of confi nement with decreasing collisionality was driven by a large reduction in electron transport in the outer region of the plasma. This result is consistent with gyrokinetic calculations that show microtearing and Electron Temperature Gradient modes to be more stable for the lower collisionality discharges. Ion transport, near neoclassical at high collisionality, became more anomalous at lower collisionality, possibly due to the growth of hybrid TEM/KBM modes in the outer regions of the plasma.

  17. The Dependence of H-mode Energy Confinement and Transport on Collisionality in NSTX

    SciTech Connect

    Kaye, S. M.; Gerhardt, S.; Guttenfelder, W.; Maingi, R.; Bell, R. E.; Diallo, A.; LeBlanc, B. P.; Podesta, M.

    2012-11-28

    Understanding the dependence of confi nement on collisionality in tokamaks is important for the design of next-step devices, which will operate at collisionalities at least one order of magnitude lower than in present generation. A wide range of collisionality has been obtained in the National Spherical Torus Experiment (NSTX) by employing two different wall conditioning techniques, one with boronization and between-shot helium glow discharge conditioning (HeGDC+B), and one using lithium evaporation (Li EVAP). Previous studies of HeGDC+B plasmas indicated a strong and favorable dependence of normalized con nement on collisionality. Discharges with lithium conditioning discussed in the present study gen- erally achieved lower collisionality, extending the accessible range of collisionality by almost an order of unity. While the confinement dependences on dimensional, engineering variables of the HeGDC+B and Li EVAP datasets differed, collisionality was found to unify the trends, with the lower collisionality lithium conditioned discharges extending the trend of increasing normalized confi nement time with decreasing collisionality when other dimension less variables were held as fi xed as possible. This increase of confi nement with decreasing collisionality was driven by a large reduction in electron transport in the outer region of the plasma. This result is consistent with gyrokinetic calculations that show microtearing and Electron Temperature Gradient modes to be more stable for the lower collisionality discharges. Ion transport, near neoclassical at high collisionality, became more anomalous at lower collisionality, possibly due to the growth of hybrid TEM/KBM modes in the outer regions of the plasma

  18. Vacuum calculations in azimuthally symmetric geometry

    Microsoft Academic Search

    M. S. Chance

    1997-01-01

    A robustly accurate and effective method is presented to solve Laplace{close_quote}s equation in general azimuthally symmetric geometry for the magnetic scalar potential in the region surrounding a plasma discharge which may or may not contain external conductors. These conductors can be topologically toroidal or spherical, and may have toroidal gaps in them. The solution is incorporated into the various magnetohydrodynamic

  19. Vacuum calculations in azimuthally symmetric geometry

    Microsoft Academic Search

    M. S. Chance

    1997-01-01

    A robustly accurate and effective method is presented to solve Laplace’s equation in general azimuthally symmetric geometry for the magnetic scalar potential in the region surrounding a plasma discharge which may or may not contain external conductors. These conductors can be topologically toroidal or spherical, and may have toroidal gaps in them. The solution is incorporated into the various magnetohydrodynamic

  20. VACUUM calculation in azimuthally symmetric geometry

    Microsoft Academic Search

    1996-01-01

    A robustly accurate and effective method is presented to solve Laplace`s equation in general azimuthally symmetric geometry for the magnetic scalar potential in the region surrounding a plasma discharge which may or may not contain external conducting shells. These shells can be topologically toroidal or spherical, and may have toroidal gaps in them. The solution is incorporated into the various

  1. Higher order moments of multiparticle azimuthal correlations

    E-print Network

    Ante Bilandzic

    2014-10-14

    We introduce a general procedure to pave the road towards the ultimate goal of deriving analytic expressions for the probability density functions (p.d.f.'s) of multiparticle azimuthal correlations. All multiparticle azimuthal correlators can be expressed analytically in terms of the real and imaginary parts of $M$-particle $Q$-vectors. We derive the analytic results for the p.d.f.'s of single-particle $Q$-vectors in the most general case and demonstrate that they can be expressed solely in terms of Chebyshev polynomials of the first kind. This leads analytically to the expressions of the characteristic functions of $M$-particle $Q$-vectors in terms of Bessel functions of the first kind. From the obtained characteristics functions we calculate the higher order moments of the real and imaginary parts of $M$-particle $Q$-vectors and use them to obtain the higher order moments of multiparticle azimuthal correlators. Finally, these results are used to investigate the sensitivity of multiparticle azimuthal correlations and to illuminate requirements necessary for future anisotropic flow measurements.

  2. Continuous energy, multi-dimensional discrete ordinates transport calculations for problem dependent resonance treatment

    NASA Astrophysics Data System (ADS)

    Zhong, Zhaopeng

    In the past twenty 20 years considerable progress has been made in developing new methods for solving the multi-dimensional transport problem. However the effort devoted to the resonance self-shielding calculation has lagged, and much less progress has been made in enhancing resonance-shielding techniques for generating problem-dependent multi-group cross sections (XS) for the multi-dimensional transport calculations. In several applications, the error introduced by self-shielding methods exceeds that due to uncertainties in the basic nuclear data, and often they can be the limiting factor on the accuracy of the final results. This work is to improve the accuracy of the resonance self-shielding calculation by developing continuous energy multi-dimensional transport calculations for problem dependent self-shielding calculations. A new method has been developed, it can calculate the continuous-energy neutron fluxes for the whole two-dimensional domain, which can be utilized as weighting function to process the self-shielded multi-group cross sections for reactor analysis and criticality calculations, and during this process, the two-dimensional heterogeneous effect in the resonance self-shielding calculation can be fully included. A new code, GEMINEWTRN (Group and Energy-Pointwise Methodology Implemented in NEWT for Resonance Neutronics) has been developed in the developing version of SCALE [1], it combines the energy pointwise (PW) capability of the CENTRM [2] with the two-dimensional discrete ordinates transport capability of lattice physics code NEWT [14]. Considering the large number of energy points in the resonance region (typically more than 30,000), the computational burden and memory requirement for GEMINEWTRN is tremendously large, some efforts have been performed to improve the computational efficiency, parallel computation has been implemented into GEMINEWTRN, which can save the computation and memory requirement a lot; some energy points reducing techniques have also been developed, improving the computational efficiency at the meanwhile preserving the accuracy. These efforts make the new method much more feasible for practical use.

  3. Lagrangian and Eulerian analysis of transport and mixing in the three dimensional, time dependent Hill's spherical vortex

    NASA Astrophysics Data System (ADS)

    McIlhany, Kevin L.; Guth, Stephen; Wiggins, Stephen

    2015-06-01

    In this paper, we extend the notion of Eulerian indicators (EIs), previously developed for two dimensional time dependent flows, to three dimensional time dependent flows, where the time dependence can be arbitrary. These are applied to a study of transport and mixing in the Hill's spherical vortex subject to a linear strain rate field. We consider the axisymmetric case and the fully three dimensional case with different types of time dependence. We develop a Lagrangian characterization of transport and mixing appropriate for open three dimensional flows and we show that the EIs provide a detailed description of the flow structure that can be correlated with the Lagrangian transport and mixing results. The EIs yield results consistent with the dynamics of the Hill's vortex flow characteristics, correlation with transverse shear, and anti-correlation with transversality.

  4. Blood-to-retina transport of biotin via Na+-dependent multivitamin transporter (SMVT) at the inner blood-retinal barrier.

    PubMed

    Ohkura, Yumiko; Akanuma, Shin-ichi; Tachikawa, Masanori; Hosoya, Ken-ichi

    2010-09-01

    The purpose of this study was to elucidate the mechanisms of biotin transport across the inner blood-retinal barrier (inner BRB). [(3)H]Biotin transport in the retina across the inner BRB was examined using an in vivo integration plot and retinal uptake index analyses in rats. The transport mechanism was characterized using a conditionally immortalized rat retinal capillary endothelial cell line (TR-iBRB2 cells) as an in vitro inner BRB model. The apparent influx permeability clearance (K(in)) per gram retina of [(3)H]biotin was found to be 5.55 microL/(min g retina). The K(in) of [(3)H]biotin was 8.9-fold greater than that of [(3)H]D-mannitol, a non-permeable paracellular marker. [(3)H]Biotin uptake by the retina was found to be significantly inhibited by biotin and pantothenic acid, supporting carrier-mediated influx transport of biotin at the inner BRB. [(3)H]Biotin uptake by TR-iBRB2 cells was Na(+)-, temperature-, and concentration-dependent with a K(m) of 146 microM. These forms of transport were significantly inhibited by Na(+)-dependent multivitamin transporter (SMVT) substrates such as biotin, pantothenic acid, lipoic acid, and desthiobiotin. These transport properties are consistent with those of biotin transport by SMVT. SMVT mRNA was expressed in TR-iBRB2 cells and isolated rat retinal vascular endothelial cells. Our findings suggest that SMVT is involved in the transport of biotin from the circulating blood to the retina across the inner BRB. PMID:20599968

  5. A sodium- and energy-dependent glucose transporter with similarities to SGLT1–2 is expressed in bovine cortical vessels

    Microsoft Academic Search

    Tomoyuki Nishizaki; Anja Kammesheidt; Katumi Sumikawa; Takashi Asada; Yasuhiro Okada

    1995-01-01

    In order to investigate glucose transport at the blood-brain barrier (BBB), glucose transport properties were studied pharmacologically with a novel model system of inverted bovine brain cortical arteries. These vessels displayed glucose transport characteristics of facilitative glucose transporters (GLUT1–5) and of sodium- and energy-dependent glucose transporters (SGLT1–2). So far, glucose transport in the central nervous system (CNS) has only been

  6. Variable effects of nitrate on ATP-dependent proton transport by barley root membranes. [Hordeum vulgare

    SciTech Connect

    DuPont, F.M.

    1987-06-01

    The effects of NO/sub 3//sup -/ and assay temperature on proton translocating ATPases in membranes of barley (Hordeum vulgare L. cv California Mariout 72) roots were examined. The membranes were fractionated on continuous and discontinuous sucrose gradients and proton transport was assayed by monitoring the fluorescence of acridine orange. A peak of H/sup +/-ATPase at 1.11 grams per cubic centimeter was inhibited by 50 millimolar KNO/sub 3/ when assayed at 24/sup 0/C or above and was tentatively identified as the tonoplast H/sup +/-ATPase. A smaller peak of H/sup +/-ATPase at 1.16 grams per cubic centimeter, which was not inhibited by KNO/sub 3/ and was partially inhibited by vanadate, was tentatively identified as the plasma membrane H/sup +/-ATPase. A step gradient gave three fractions enriched, respectively, in endoplasmic reticulum, tonoplast ATPase, and plasma membrane ATPase. There was a delay before 50 millimolar KNO/sub 3/ inhibited ATP hydrolysis by the tonoplast ATPase at 12/sup 0/C and the initial rate of proton transport was stimulated by 50 millimolar KNO/sub 3/. The time course for fluorescence quench indicated that addition of ATP in the presence of KNO/sub 3/ caused a pH gradient to form that subsequently collapsed. This biphasic time course for proton transport in the presence of KNO/sub 3/ was explained by the temperature-dependent delay of the inhibition by KNO/sub 3/. The plasma membrane H/sup +/-ATPase maintained a pH gradient in the presence of KNO/sub 3/ for up to 30 minutes at 24/sup 0/C.

  7. Temperature Dependent Electrical Transport Properties of Ni-Cr and Co-Cr Binary Alloys

    SciTech Connect

    Thakore, B. Y.; Khambholja, S. G.; Bhatt, N. K.; Jani, A. R. [Department of Physics, S P University, Vallabh Vidhyanagar, 388 120, Gujarat (India); Suthar, P. H. [Department of Physics, C U Shah Science College, Ahmedabad, 380 014, Gujarat (India); Gajjar, P. N. [Department of Physics, University Schools of Sciences, Gujarat University, Ahmedabad, 380 009, Gujarat (India)

    2011-12-12

    The temperature dependent electrical transport properties viz. electrical resistivity and thermal conductivity of Ni{sub 10}Cr{sub 90} and Co{sub 20}Cr{sub 80} alloys are computed at various temperatures. The electrical resistivity has been calculated according to Faber-Ziman model combined with Ashcroft-Langreth partial structure factors. In the present work, to include the ion-electron interaction, we have used a well tested local model potential. For exchange-correlation effects, five different forms of local field correction functions due to Hartree (H), Taylor (T), Ichimaru and Utsumi (IU), Farid et al (F) and Sarkar et al (S) are used. The present results due to S function are in good agreement with the experimental data as compared to results obtained using other four functions. The S functions satisfy compressibility sum rule in long wave length limit more accurately as compared to T, IU and F functions, which may be responsible for better agreement of results, obtained using S function. Also, present result confirms the validity of present approach in determining the transport properties of alloys like Ni-Cr and Co-Cr.

  8. Temperature Dependent Electrical Transport Properties of Ni-Cr and Co-Cr Binary Alloys

    NASA Astrophysics Data System (ADS)

    Thakore, B. Y.; Suthar, P. H.; Khambholja, S. G.; Gajjar, P. N.; Bhatt, N. K.; Jani, A. R.

    2011-12-01

    The temperature dependent electrical transport properties viz. electrical resistivity and thermal conductivity of Ni10Cr90 and Co20Cr80 alloys are computed at various temperatures. The electrical resistivity has been calculated according to Faber-Ziman model combined with Ashcroft-Langreth partial structure factors. In the present work, to include the ion-electron interaction, we have used a well tested local model potential. For exchange-correlation effects, five different forms of local field correction functions due to Hartree (H), Taylor (T), Ichimaru and Utsumi (IU), Farid et al (F) and Sarkar et al (S) are used. The present results due to S function are in good agreement with the experimental data as compared to results obtained using other four functions. The S functions satisfy compressibility sum rule in long wave length limit more accurately as compared to T, IU and F functions, which may be responsible for better agreement of results, obtained using S function. Also, present result confirms the validity of present approach in determining the transport properties of alloys like Ni-Cr and Co-Cr.

  9. Azimuth determination of and from horizontal ocean bottom seismic sensors

    Microsoft Academic Search

    F. K. Duennebier; P. N. Anderson; G. J. Fryer

    1987-01-01

    A number of factors must be considered when using particle motion information to determine azimuths to source or azimuths of horizontal geophone axes on or below the ocean floor. These factors include anisotropy, unmatched sensor response, incorrect instrument location, tilted sensors or dipping structure, and poor coupling. Accurate determination of azimuths requires identification and understanding of these factors and their

  10. Temperature and Gas-Environment Dependent Electron and Phonon Transport in Suspended Carbon Nanotubes Up to Electrical Breakdown

    Microsoft Academic Search

    David Mann; Eric Pop; Jien Cao; Qian Wang; Kenneth Goodson; Hongjie Dai

    2005-01-01

    High bias electrical transport characteristics of freely suspended metallic single-walled carbon nanotubes (SWNTs) are investigated at 250-400K in vacuum and various gases. Self-heating is exploited to examine the temperature dependence of phonon transport and optical phonon decay in SWNTs. The acoustic phonon thermal conductivity of a SWNT follows ~1\\/T at high temperatures. Non-equilibrium optical phonon effects in suspended nanotubes decrease

  11. Demonstration of ATP dependent, transcellular transport of lipid across the lymphatic endothelium using an in vitro model of the lacteal

    PubMed Central

    Reed, Alana L.; Rowson, Sydney A.; Dixon, J. Brandon

    2013-01-01

    Purpose The lymphatic system plays crucial roles in tissue fluid balance, trafficking of immune cells, and the uptake of dietary lipid from the intestine. Given these roles there has been an interest in targeting lymphatics through oral lipid-based formulations or intradermal delivery of drug carrier systems. However the mechanisms regulating lipid uptake by lymphatics remain unknown. Thus we sought to modify a previously developed in vitro model to investigate the role of ATP in lipid uptake into the lymphatics. Methods Lymphatic endothelial cells were cultured on a transwell membrane and the effective permeability to free fatty acid and Caco-2 cell-secreted lipid was calculated in the presence or absence of the ATP-inhibitor sodium azide. Results: ATP inhibition reduced Caco-2 cell-secreted lipid transport, but not dextran transport. FFA transport was ATP-dependent primarily during early periods of ATP-inhibition, while Caco-2 cell-secreted lipid transport was lowered at all time points studied. Furthermore, the transcellular component of transport was highly ATP-dependent, a mechanism not observed in fibroblasts, suggesting these mechanisms are unique to lymphatics. Total transport of Caco-2 cell-secreted lipid was dose-dependently reduced by ATP inhibition, and transcellular lipoprotein transport was completely attenuated. Conclusion The transport of lipid across the lymphatic endothelium as demonstrated with this in vitro model occurs in part by an ATP-dependent, transcellular route independent of passive permeability. It remains to be determined the extent that this mechanism exists in vivo and future work should be directed in this area. PMID:24254195

  12. Measurement of azimuthal hadron asymmetries in semi-inclusive deep inelastic scattering off unpolarised nucleons

    NASA Astrophysics Data System (ADS)

    Adolph, C.; Akhunzyanov, R.; Alexeev, M. G.; Alexandrov, Yu.; Alexeev, G. D.; Amoroso, A.; Andrieux, V.; Anosov, V.; Austregesilo, A.; Bade?ek, B.; Balestra, F.; Barth, J.; Baum, G.; Beck, R.; Bedfer, Y.; Berlin, A.; Bernhard, J.; Bertini, R.; Bicker, K.; Bieling, J.; Birsa, R.; Bisplinghoff, J.; Bodlak, M.; Boer, M.; Bordalo, P.; Bradamante, F.; Braun, C.; Bravar, A.; Bressan, A.; Büchele, M.; Burtin, E.; Capozza, L.; Chiosso, M.; Chung, S. U.; Cicuttin, A.; Crespo, M. L.; Curiel, Q.; Dalla Torre, S.; Dasgupta, S. S.; Dasgupta, S.; Denisov, O. Yu.; Donskov, S. V.; Doshita, N.; Duic, V.; Dünnweber, W.; Dziewiecki, M.; Efremov, A.; Elia, C.; Eversheim, P. D.; Eyrich, W.; Faessler, M.; Ferrero, A.; Filin, A.; Finger, M.; Finger, M.; Fischer, H.; Franco, C.; du Fresne von Hohenesche, N.; Friedrich, J. M.; Frolov, V.; Garfagnini, R.; Gautheron, F.; Gavrichtchouk, O. P.; Gerassimov, S.; Geyer, R.; Giorgi, M.; Gnesi, I.; Gobbo, B.; Goertz, S.; Gorzellik, M.; Grabmüller, S.; Grasso, A.; Grube, B.; Guskov, A.; Guthörl, T.; Haas, F.; von Harrach, D.; Hahne, D.; Hashimoto, R.; Heinsius, F. H.; Herrmann, F.; Hinterberger, F.; Höppner, Ch.; Horikawa, N.; d'Hose, N.; Huber, S.; Ishimoto, S.; Ivanov, A.; Ivanshin, Yu.; Iwata, T.; Jahn, R.; Jary, V.; Jasinski, P.; Joerg, P.; Joosten, R.; Kabuß, E.; Kang, D.; Ketzer, B.; Khaustov, G. V.; Khokhlov, Yu. A.; Kisselev, Yu.; Klein, F.; Klimaszewski, K.; Koivuniemi, J. H.; Kolosov, V. N.; Kondo, K.; Königsmann, K.; Konorov, I.; Konstantinov, V. F.; Kotzinian, A. M.; Kouznetsov, O.; Kral, Z.; Krämer, M.; Kroumchtein, Z. V.; Kuchinski, N.; Kunne, F.; Kurek, K.; Kurjata, R. P.; Lednev, A. A.; Lehmann, A.; Levorato, S.; Lichtenstadt, J.; Maggiora, A.; Magnon, A.; Makke, N.; Mallot, G. K.; Marchand, C.; Martin, A.; Marzec, J.; Matousek, J.; Matsuda, H.; Matsuda, T.; Meshcheryakov, G.; Meyer, W.; Michigami, T.; Mikhailov, Yu. V.; Miyachi, Y.; Nagaytsev, A.; Nagel, T.; Nerling, F.; Neubert, S.; Neyret, D.; Nikolaenko, V. I.; Novy, J.; Nowak, W.-D.; Nunes, A. S.; Orlov, I.; Olshevsky, A. G.; Ostrick, M.; Panknin, R.; Panzieri, D.; Parsamyan, B.; Paul, S.; Pesek, M.; Peshekhonov, D.; Piragino, G.; Platchkov, S.; Pochodzalla, J.; Polak, J.; Polyakov, V. A.; Pretz, J.; Quaresma, M.; Quintans, C.; Ramos, S.; Reicherz, G.; Rocco, E.; Rodionov, V.; Rondio, E.; Rychter, A.; Rossiyskaya, N. S.; Ryabchikov, D. I.; Samoylenko, V. D.; Sandacz, A.; Sarkar, S.; Savin, I. A.; Sbrizzai, G.; Schiavon, P.; Schill, C.; Schlüter, T.; Schmidt, A.; Schmidt, K.; Schmieden, H.; Schönning, K.; Schopferer, S.; Schott, M.; Shevchenko, O. Yu.; Silva, L.; Sinha, L.; Sirtl, S.; Slunecka, M.; Sosio, S.; Sozzi, F.; Srnka, A.; Steiger, L.; Stolarski, M.; Sulc, M.; Sulej, R.; Suzuki, H.; Szableski, A.; Szameitat, T.; Sznajder, P.; Takekawa, S.; ter Wolbeek, J.; Tessaro, S.; Tessarotto, F.; Thibaud, F.; Uhl, S.; Uman, I.; Vandenbroucke, M.; Virius, M.; Vondra, J.; Wang, L.; Weisrock, T.; Wilfert, M.; Windmolders, R.; Wi?licki, W.; Wollny, H.; Zaremba, K.; Zavertyaev, M.; Zemlyanichkina, E.; Ziembicki, M.

    2014-09-01

    Spin-averaged asymmetries in the azimuthal distributions of positive and negative hadrons produced in deep inelastic scattering were measured using the CERN SPS longitudinally polarised muon beam at 160 GeV/c and a 6LiD target. The amplitudes of the three azimuthal modulations cos??h, cos?2?h and sin??h were obtained binning the data separately in each of the relevant kinematic variables x, z or pTh and binning in a three-dimensional grid of these three variables. The amplitudes of the cos??h and cos?2?h modulations show strong kinematic dependencies both for positive and negative hadrons.

  13. Neuronal transporter and astrocytic ATP exocytosis underlie activity-dependent adenosine release in the hippocampus

    PubMed Central

    Wall, Mark J; Dale, Nicholas

    2013-01-01

    The neuromodulator adenosine plays an important role in many physiological and pathological processes within the mammalian CNS. However, the precise mechanisms of how the concentration of extracellular adenosine increases following neural activity remain contentious. Here we have used microelectrode biosensors to directly measure adenosine release induced by focal stimulation in stratum radiatum of area CA1 in mouse hippocampal slices. Adenosine release was both action potential and Ca2+ dependent and could be evoked with low stimulation frequencies and small numbers of stimuli. Adenosine release required the activation of ionotropic glutamate receptors and could be evoked by local application of glutamate receptor agonists. Approximately 40% of stimulated-adenosine release occurred by translocation of adenosine via equilibrative nucleoside transporters (ENTs). This component of release persisted in the presence of the gliotoxin fluoroacetate and thus results from the direct release of adenosine from neurons. A reduction of adenosine release in the presence of NTPDase blockers, in slices from CD73?/? and dn-SNARE mice, provides evidence that a component of adenosine release arises from the extracellular metabolism of ATP released from astrocytes. This component of release appeared to have slower kinetics than the direct ENT-mediated release of adenosine. These data suggest that activity-dependent adenosine release is surprisingly complex and, in the hippocampus, arises from at least two distinct mechanisms with different cellular sources. PMID:23713028

  14. Magnetic Resonance Microscopy of Scale Dependent Transport Phenomena and Bioactivity in Porous Media

    NASA Astrophysics Data System (ADS)

    Seymour, J. D.; Codd, S. L.; Romanenko, K. V.; Hornemann, J. A.; Brosten, T. R.

    2008-05-01

    Magnetic resonance microscopy (MRM) provides the ability to obtain data on the pore scale via imaging and the sample scale by bulk measurement, allowing for connection between microscale dynamics and macroscale transport phenomena. This has led to MRM techniques becoming a preeminent method for characterization of dynamics in porous media. A significant question in modeling transport in porous media is definition of the porous media structure as homogeneous (ordered) or heterogeneous (disordered)[1]. One means of defining the 'complexity' of a porous media is based on the dynamics of the system[2]. The ability of MRM to measure the time dependent statistics of the dynamics [3,4,5] provides quantification of the pre-asymptotic dynamics. The transition from preasymptotic to Gaussian transport consistent with models of homogeneous porous media is clearly visualized. Biological activity in porous media, such as microbial growth, typically manifests itself as biofilms or colonies of microbes that adhere to surfaces and are surrounded by a hydrogel of extracellular polymeric substance (EPS). The biofilm growth introduces complexity into the system structure in generation of physical pore blocking, trapping within the EPS gel, elastic interfaces due to the EPS and generation of channels in which faster flow occur. The hierarchy of length and time scales and multiple physical processes which are introduced by the biofilm growth impacts the porous media transport as reflected in the change in dynamics [6]. The transition can be modeled using statistical mechanical approaches based on continuous time random walk (CTRW) processes that generate fractional differential equations[7]. The bioactivity alters the structure of the porous media from homogeneous to heterogeneous resulting in the transition from a Gaussian to a non Gaussian subdiffusive dispersion process. References 1. M. Quintard and S. Whitaker, Transport in ordered and disordered porous media: Volume averaged equations, closure problems and comparison with experiment. Chemical Engineering Science, 48(14): 2537-2564 (1993). 2. N. Goldenfeld and L.P. Kadanoff, Simple lessons from complexity. Science, 284: 87-89 (1999). 3. J.D. Seymour and P.T. Callaghan, Generalized approach to NMR analysis of flow and dispersion in porous medium. AIChE Journal, 43: 2096-2111 (1997). 4. S.L. Codd, B. Manz, J.D. Seymour, and P.T. Callaghan, Taylor dispersion and molecular displacements in poiseuille flow. Physical Review E, 60(4): R3491-R3494 (1999). 5. P.T. Callaghan, Principles of Nuclear Magnetic Resonance Microscopy. New York: Oxford University Press (1991). 6. G.K. Batchelor, Developments in microhydrodynamics, in Theoretical and Applied Mechanics, W.T. Koiter, Editor. North-Holland: Amsterdam. p. 33-55 (1976). 7. J.D. Seymour, J.P. Gage, S.L. Codd, and R. Gerlach, Anomalous fluid transport in porous media induced by biofilm growth. Physical Review Letters, 93: 198103 (2004).

  15. Carbohydrate Kinase (RhaK)-Dependent ABC Transport of Rhamnose in Rhizobium leguminosarum Demonstrates Genetic Separation of Kinase and Transport Activities

    PubMed Central

    Rivers, Damien

    2013-01-01

    In Rhizobium leguminosarum the ABC transporter responsible for rhamnose transport is dependent on RhaK, a sugar kinase that is necessary for the catabolism of rhamnose. This has led to a working hypothesis that RhaK has two biochemical functions: phosphorylation of its substrate and affecting the activity of the rhamnose ABC transporter. To address this hypothesis, a linker-scanning random mutagenesis of rhaK was carried out. Thirty-nine linker-scanning mutations were generated and mapped. Alleles were then systematically tested for their ability to physiologically complement kinase and transport activity in a strain carrying an rhaK mutation. The rhaK alleles generated could be divided into three classes: mutations that did not affect either kinase or transport activity, mutations that eliminated both transport and kinase activity, and mutations that affected transport activity but not kinase activity. Two genes of the last class (rhaK72 and rhaK73) were found to have similar biochemical phenotypes but manifested different physiological phenotypes. Whereas rhaK72 conferred a slow-growth phenotype when used to complement rhaK mutants, the rhaK73 allele did not complement the inability to use rhamnose as a sole carbon source. To provide insight to how these insertional variants might be affecting rhamnose transport and catabolism, structural models of RhaK were generated based on the crystal structure of related sugar kinases. Structural modeling suggests that both rhaK72 and rhaK73 affect surface-exposed residues in two distinct regions that are found on one face of the protein, suggesting that this protein's face may play a role in protein-protein interaction that affects rhamnose transport. PMID:23708135

  16. Azimuthal asymmetries from unpolarized data at COMPASS

    E-print Network

    C. Schill; for the COMPASS collaboration

    2011-07-12

    The investigation of transverse spin and transverse momentum effects in the nucleon is one of the key physics programs of the COMPASS experiment at CERN. COMPASS investigates these effects scattering 160 GeV/c muons off a fixed NH3 or 6LiD target. The azimuthal asymmetries which appear in the cross-section of semi-inclusive deep-inelastic scattering on an unpolarized target have been measured. These asymmetries give insight into the intrinsic transverse momentum of the quarks in the nucleon by the Cahn effect and into a possible correlation between transverse momentum and transverse spin. New results for azimuthal asymmetries of single hadrons produced in scattering muons off an unpolarized 6LiD target are presented.

  17. Measurements of unpolarised azimuthal asymmetries at COMPASS

    E-print Network

    Giulio Sbrizzai; for the COMPASS Collaboration

    2009-02-03

    Azimuthal asymmetries in unpolarized SIDIS can be used to probe the transverse momentum of the quarks inside the nucleon. Furthermore they give access to the so-far unmeasured Boer-Mulders function. We report on the extraction of these asymmetries from the COMPASS data taken with a 160 GeV/c $\\mu ^+$ beam impinging on a deuteron target. This asymmetries have been extracted separately for positive and negative hadrons, and the results have been compared with theoretical predictions.

  18. Origin of azimuthal seismic anisotropy in oceanic plates and mantle

    NASA Astrophysics Data System (ADS)

    Becker, Thorsten W.; Conrad, Clinton P.; Schaeffer, Andrew J.; Lebedev, Sergei

    2014-09-01

    Seismic anisotropy is ubiquitous in the Earth's mantle but strongest in its thermo-mechanical boundary layers. Azimuthal anisotropy in the oceanic lithosphere and asthenosphere can be imaged by surface waves and should be particularly straightforward to relate to well-understood plate kinematics and large-scale mantle flow. However, previous studies have come to mixed conclusions as to the depth extent of the applicability of paleo-spreading and mantle flow models of anisotropy, and no simple, globally valid, relationships exist. Here, we show that lattice preferred orientation (LPO) inferred from mantle flow computations produces a plausible global background model for asthenospheric anisotropy underneath oceanic lithosphere. The same is not true for absolute plate motion (APM) models. A ˜200 km thick layer where the flow model LPO matches observations from tomography lies just below the ˜1200 °C isotherm of a half-space cooling model, indicating strong temperature-dependence of the processes that control the development of azimuthal anisotropy. We infer that the depth extent of shear, and hence the thickness of a relatively strong oceanic lithosphere, can be mapped this way. These findings for the background model, and ocean-basin specific deviations from the half-space cooling pattern, are found in all of the three recent and independent tomographic models considered. Further exploration of deviations from the background model may be useful for general studies of oceanic plate formation and dynamics as well as regional-scale tectonic analyses.

  19. Azimuthal and zenithal anchoring of nematic liquid crystals.

    PubMed

    Vilfan, Mojca; Copic, Martin

    2003-09-01

    Temperature dependence of azimuthal and zenithal anchoring energy coefficients of the nematic liquid crystal 4-n-pentyl-4(')-cyanobiphenyl on rubbed nylon is measured using dynamic light scattering. The method is based on observations of director fluctuations in a planarly aligned wedge cell, where the anchoring energy coefficients can be obtained without any external torques acting on the liquid crystal during the measurement. We found that both anchoring coefficients decrease steadily on approaching the nematic-isotropic transition. Moreover, in the whole temperature range of the nematic phase, the ratio between the zenithal and the azimuthal anchoring coefficients is almost equal to the ratio between the splay and the twist Frank elastic constants. The same result is obtained also for the nematic phase of 4-n-octyl-4(')-cyanobiphenyl. This indicates that the aligning nylon layer directly affects only the monomolecular layer at the surface whereas the observed anchoring is governed by the elastic properties of the alkyl-cyanobiphenyl. PMID:14524785

  20. Enteropathogenic Escherichia coli inhibits ileal sodium-dependent bile acid transporter ASBT

    PubMed Central

    Annaba, Fadi; Sarwar, Zaheer; Gill, Ravinder K.; Ghosh, Amit; Saksena, Seema; Borthakur, Alip; Hecht, Gail A.; Dudeja, Pradeep K.

    2012-01-01

    Apical sodium-dependent bile acid transporter (ASBT) is responsible for the absorption of bile acids from the intestine. A decrease in ASBT function and expression has been implicated in diarrhea associated with intestinal inflammation. Whether infection with pathogenic microorganisms such as the enteropathogenic Escherichia coli (EPEC) affect ASBT activity is not known. EPEC is a food-borne enteric pathogen that translocates bacterial effector molecules via type three secretion system (TTSS) into host cells and is a major cause of infantile diarrhea. We investigated the effects of EPEC infection on ileal ASBT function utilizing human intestinal Caco2 cells and HEK-293 cells stably transfected with ASBT-V5 fusion protein (2BT cells). ASBT activity was significantly inhibited following 60 min infection with EPEC but not with nonpathogenic E. coli. Mutations in bacterial escN, espA, espB, and espD, the genes encoding for the elements of bacterial TTSS, ablated EPEC inhibitory effect on ASBT function. Furthermore, mutation in the bacterial BFP gene encoding for bundle-forming pili abrogated the inhibition of ASBT by EPEC, indicating the essential role for bacterial aggregation and the early attachment. The inhibition by EPEC was associated with a significant decrease in the Vmax of the transporter and a reduction in the level of ASBT on the plasma membrane. The inhibition of ASBT by EPEC was blocked in the presence of protein tyrosine phosphatase inhibitors. Our studies provide novel evidence for the alterations in the activity of ASBT by EPEC infection and suggest a possible effect for EPEC in influencing intestinal bile acid homeostasis. PMID:22403793

  1. Enteropathogenic Escherichia coli inhibits ileal sodium-dependent bile acid transporter ASBT.

    PubMed

    Annaba, Fadi; Sarwar, Zaheer; Gill, Ravinder K; Ghosh, Amit; Saksena, Seema; Borthakur, Alip; Hecht, Gail A; Dudeja, Pradeep K; Alrefai, Waddah A

    2012-05-15

    Apical sodium-dependent bile acid transporter (ASBT) is responsible for the absorption of bile acids from the intestine. A decrease in ASBT function and expression has been implicated in diarrhea associated with intestinal inflammation. Whether infection with pathogenic microorganisms such as the enteropathogenic Escherichia coli (EPEC) affect ASBT activity is not known. EPEC is a food-borne enteric pathogen that translocates bacterial effector molecules via type three secretion system (TTSS) into host cells and is a major cause of infantile diarrhea. We investigated the effects of EPEC infection on ileal ASBT function utilizing human intestinal Caco2 cells and HEK-293 cells stably transfected with ASBT-V5 fusion protein (2BT cells). ASBT activity was significantly inhibited following 60 min infection with EPEC but not with nonpathogenic E. coli. Mutations in bacterial escN, espA, espB, and espD, the genes encoding for the elements of bacterial TTSS, ablated EPEC inhibitory effect on ASBT function. Furthermore, mutation in the bacterial BFP gene encoding for bundle-forming pili abrogated the inhibition of ASBT by EPEC, indicating the essential role for bacterial aggregation and the early attachment. The inhibition by EPEC was associated with a significant decrease in the V(max) of the transporter and a reduction in the level of ASBT on the plasma membrane. The inhibition of ASBT by EPEC was blocked in the presence of protein tyrosine phosphatase inhibitors. Our studies provide novel evidence for the alterations in the activity of ASBT by EPEC infection and suggest a possible effect for EPEC in influencing intestinal bile acid homeostasis. PMID:22403793

  2. Selective and Cytokine-Dependent Regulation of Hepatic Transporters and Bile Acid Homeostasis during Infectious Colitis in Mice

    PubMed Central

    Merrell, Matthew D.; Nyagode, Beatrice A.; Clarke, John D.; Cherrington, Nathan J.

    2014-01-01

    Various disease models have been shown to alter hepatic drug-metabolizing enzyme (DME) and transporter expression and to induce cholestasis through altered enzyme and transporter expression. Previously, we detailed the regulation of hepatic DMEs during infectious colitis caused by Citrobacter rodentium infection. We hypothesized that this infection would also modulate hepatic drug transporter expression and key genes of bile acid (BA) synthesis and transport. Mice lacking Toll-like receptor 4 (TLR4), interleukin-6 (IL-6), or interferon-gamma (IFN?) and appropriate wild-type animals were orally infected with C. rodentium and sacrificed 7 days later. In two wild-type strains, drug transporter mRNA expression was significantly decreased by infection for Slc22a4, Slco1a1, Slco1a4, Slco2b1, and Abcc6, whereas the downregulation of Abcc2, Abcc3, and Abcc4 were strain-dependent. In contrast, mRNA expressions of Slco3a1 and Abcb1b were increased in a strain-dependent manner. Expression of Abcb11, Slc10a1, the two major hepatic BA transporters, and Cyp7a1, the rate-limiting enzyme of BA synthesis, was also significantly decreased in infected animals. None of the above effects were caused by bacterial lipopolysaccharide, since they still occurred in the absence of functional TLR4. The downregulation of Slc22a4 and Cyp7a1 was absent in IFN?-null mice, and the downregulation of Slco1a1 was abrogated in IL-6-null mice, indicating in vivo roles for these cytokines in transporter regulation. These data indicate that C. rodentium infection modulates hepatic drug processing through alteration of transporter expression as well as DMEs. Furthermore, this infection downregulates important genes of BA synthesis and transport and may increase the risk for cholestasis. PMID:24378326

  3. Noncoplanar PCB 95 alters microsomal calcium transport by an immunophilin FKBP12-dependent mechanism.

    PubMed

    Wong, P W; Pessah, I N

    1997-05-01

    Ortho-substituted polychlorinated biphenyls (PCBs) have been shown to alter microsomal Ca2+ transport by selective interaction with ryanodine receptors (RyRs) of muscle sarcoplasmic reticulum (SR) and brain endoplasmic reticulum. The mechanism underlying the actions of PCBs on Ca2+ transport is further elucidated with skeletal SR enriched in Ry1R. Disruption of the association between immunophilin FKBP12 and Ry1R with FK 506 or rapamycin completely eliminates PCB 95-enhanced binding of [3H]ryanodine (IC50 approximately 35 microM) to Ry1R and PCB 95-induced release of Ca2+ from actively loaded SR vesicles (IC50 approximately 11 microM), demonstrating a FKBP12-dependent mechanism. FK 506 selectively eliminates PCB 95-induced Ca2+ release from SR because Ry1R maintains responsiveness to caffeine and Ca2+. PCB 95 and FK 506 are used to examine the relationship between ryanodine-sensitive Ca2+ channels and ryanodine-insensitive Ca2+ leak pathways present in SR vesicles. Micromolar ryanodine completely blocks ryanodine-sensitive Ca2+ efflux but neither eliminates the ryanodine-insensitive Ca2+ leak unmasked by thapsigargin nor enhances the loading capacity of SR vesicles. PCB 95 alone enhances thapsigargin evoked Ca2+ release and therefore diminishes the loading capacity of SR vesicles. However, in the presence of micromolar ryanodine, PCB 95 dose-dependently eliminates the Ca2+ leak unmasked by thapsigargin and significantly enhances the loading capacity of SR vesicles. The actions of PCB 95 on SR-loading capacity are additive with those of FK 506. Structural specificity for these novel actions are further demonstrated with coplanar PCB 126, which is inactive toward Ry1R and lacks the ability to alter the Ca2+ leak pathway. The results reveal that FKBP12 relates ryanodine-insensitive Ca2+ "leak" and ryanodine-sensitive Ca2+ channel efflux pathways of SR by modulating distinct conformations Ry1R complexes. Noncoplanar PCBs, like PCB 95, alter SR Ca2+ buffering by an FKBP12-mediated mechanism. An immunophilin-based mechanism could account for the toxic actions attributed to certain noncoplanar PCB congeners. PMID:9145907

  4. A stromal pool of TatA promotes Tat-dependent protein transport across the thylakoid membrane.

    PubMed

    Frielingsdorf, Stefan; Jakob, Mario; Klösgen, Ralf Bernd

    2008-12-01

    In chloroplasts and bacteria, the Tat (twin-arginine translocation) system is engaged in transporting folded passenger proteins across the thylakoid and cytoplasmic membranes, respectively. To date, three membrane proteins (TatA, TatB, and TatC) have been identified to be essential for Tat-dependent protein translocation in the plant system, whereas soluble factors seem not to be required. In contrast, in the bacterial system, several cytosolic chaperones were described to be involved in Tat transport processes. Therefore, we have examined whether stromal or peripherally associated membrane proteins also play a role in Tat transport across the thylakoid membrane. Analyzing both authentic precursors as well as the chimeric 16/23 protein, which allows us to study each step of the translocation process individually, we demonstrate that a soluble form of TatA is present in the chloroplast stroma, which significantly improves the efficiency of Tat-dependent protein transport. Furthermore, this soluble TatA is able to reconstitute the Tat transport properties of thylakoid membranes that are transport-incompetent due to extraction with solutions of chaotropic salts. PMID:18842584

  5. Polarized localization and borate-dependent degradation of the Arabidopsis borate transporter BOR1 in tobacco BY-2 cells

    PubMed Central

    Matsuoka, Ken

    2013-01-01

    In Arabidopsis the borate transporter BOR1, which is located in the plasma membrane, is degraded in the presence of excess boron by an endocytosis-mediated mechanism. A similar mechanism was suggested in rice as excess boron decreased rice borate transporter levels, although in this case whether the decrease was dependent on an increase in degradation or a decrease in protein synthesis was not elucidated. To address whether the borate-dependent degradation mechanism is conserved among plant cells, we analyzed the fate of GFP-tagged BOR1 (BOR1-GFP) in transformed tobacco BY-2 cells. Cells expressing BOR1-GFP displayed GFP fluorescence at the plasma membrane, especially at the membrane between two attached cells. The plasma membrane signal was abolished when cells were incubated in medium with a high concentration of borate (3 to 5 mM). This decrease in BOR1-GFP signal was mediated by a specific degradation of the protein after internalization by endocytosis from the plasma membrane. Pharmacological analysis indicated that the decrease in BOR1-GFP largely depends on the increase in degradation rate and that the degradation was mediated by a tyrosine-motif and the actin cytoskeleton. Tyr mutants of BOR1-GFP, which has been shown to inhibit borate-dependent degradation in Arabidopsis root cells, did not show borate-dependent endocytosis in tobacco BY-2 cells. These findings indicate that the borate-dependent degradation machinery of the borate transporter is conserved among plant species. PMID:24715955

  6. INTERNATIONAL CONGRESS OF THE AERONAUTICAL SCIENCES In air transport, the evolution of traffic depends

    E-print Network

    Boyer, Edmond

    27TH INTERNATIONAL CONGRESS OF THE AERONAUTICAL SCIENCES 1 Abstract In air transport, the evolution to smaller airports. 1 Introduction During the last decade, the European air transport market saw role in the air transport industry, by improving their attractiveness and their competitiveness

  7. Molecular characterization of the 5' regulatory region of rat sodium-dependent multivitamin transporter gene.

    PubMed

    Chatterjee, N S; Rubin, S A; Said, H M

    2001-03-01

    Previous studies have demonstrated the involvement of a specialized, Na(+)-dependent carrier-mediated system for biotin uptake in mammalian intestine. The molecular identity of the carrier protein, the Na(+)-dependent multivitamin transporter (SMVT), has recently been identified. Upon characterization of transcript expression in the rat intestine, four distinct transcript variants (I-IV) due to heterogeneity at the 5'-untranslated region were found (Chatterjee NS, Kumar CK, Ortiz A, Rubin SA, and Said HM. Am J Physiol Cell Physiol 277: C605-C613, 1999). This finding raised the possibility that multiple promoters may be involved in driving the transcription of the SMVT gene. To test this possibility, we cloned the 5' regulatory region of the SMVT gene by genome walking. A 6.5-kb genomic DNA fragment was identified and sequenced. Three putative promoters (P1, P2, and P3) that were separated by exons of the four previously identified transcript variants were, indeed, found. P1 was found to contain multiple putative regulatory regions like GATA-1, AP-1, AP-2, and C/EBP, including several repeats of purine-rich regions and two TATA-like elements. P2 and P3 were GC rich and also revealed the presence of many putative regulatory elements including several SP-1 consensus sequences. The functional identity of each promoter and the minimal regions required for its function were established by the luciferase assay following transfection of rat-derived cultured intestinal epithelial IEC-6 cells. The highest functional activity of the cloned promoters was found to be in the order of P1 > P2 > P3. These findings represent the first characterization of the 5' regulatory region of any mammalian SMVT gene and should assist in the understanding of transcriptional regulation of this important gene. PMID:11171574

  8. Ballistic spin-dependent transport of Rashba rings with multi-leads

    SciTech Connect

    Huang Guangyao [State Key Laboratory of Optoelectronic Material and Technology and School of Physics and Engineering, Sun Yat-Sen University, Guangzhou 510275 (China); Liang Shidong, E-mail: stslsd@mail.sysu.edu.cn [State Key Laboratory of Optoelectronic Material and Technology and School of Physics and Engineering, Sun Yat-Sen University, Guangzhou 510275 (China)

    2011-05-15

    Research Highlights: > Transmission coefficients of each outgoing lead in multi-lead mesoscopic Rashba rings. > Spin polarizations of each outgoing lead in multi-lead mesoscopic Rashba rings. > Resonant and antiresonant conditions of spin polarization in multi-lead Rashba rings. > Symmetries of conductance and spin polarization of symmetric multi-lead Rashba rings. - Abstract: Using the Landauer-Buettiker formula with the transfer matrix technique, we develop a formalism of the ballistic spin-dependent electron transport in the multi-lead Rashba rings. We give analytic formulas of the total conductance G{sub j}, spin-{sigma} conductance g{sub j}{sup {sigma}} and spin polarization P{sub j} of each outgoing lead j, and their resonant and antiresonant conditions. Analytic studying with numerical investigating Rashba rings with several symmetric and asymmetric leads, we find that G{sub j}, g{sub j}{sup {sigma}} and P{sub j} oscillate with the incoming electron energy and the spin-orbit interaction (SOI) strength, and their antiresonances depend on the incoming electron energy, the SOI strength and the outgoing-lead angle with the incoming lead. For the symmetric-lead rings, G{sub j}, g{sub j}{sup {sigma}} and P{sub j} have some symmetries, G{sub j}=G{sub N-j},g{sub j}{sup {sigma}}=g{sub N-j}{sup -{sigma}}, and P{sub j} = -P{sub N-j} for symmetric leads, j and N - j, where the angles between the symmetric outgoing leads j and N - j and the incoming lead are {gamma}{sub N-j} = 2{pi} - {gamma}{sub j}. The spin polarization of the outgoing lead with {gamma}{sub j} = {pi} is exactly zero for even-N-symmetric-lead rings. These symmetries originate from the lead symmetry and time reversal invariance. For asymmetry-lead rings these symmetries vanish.

  9. Transport properties and Kondo correlations in nanostructures: Time-dependent DMRG method applied to quantum dots coupled to Wilson chains

    E-print Network

    Dias, Luis Gregório

    Transport properties and Kondo correlations in nanostructures: Time-dependent DMRG method applied to metallic leads. Finite-size effects make the usual tDMRG description of the Kondo regime a numerically-bias regime up to bias voltages of the order of the Kondo temperature. These results show

  10. A time dependent propagator method for long mean free path transport of neutral particles in plasma processing reactors

    E-print Network

    Kushner, Mark

    October 1995; accepted for publication 18 December 1995 Plasma etching reactors for microelectronicsA time dependent propagator method for long mean free path transport of neutral particles in plasma processing reactors Wen-yi Tan, Robert J. Hoekstra, and Mark J. Kushnera) Department of Electrical

  11. Spin-Dependent Transport in Molecular Tunnel Junctions J. R. Petta,* S. K. Slater, and D. C. Ralph

    E-print Network

    Petta, Jason

    Spin-Dependent Transport in Molecular Tunnel Junctions J. R. Petta,* S. K. Slater, and D. C. Ralph April 2004; published 20 September 2004) We present measurements of magnetic tunnel junctions made using and demonstrations that molecules can exhibit diode and transistor behaviors [1­7]. However, to date nearly all

  12. Effects of pharmaceutical products and municipal wastewaters on temperature-dependent mitochondrial electron transport activity in Elliptio complanata mussels

    Microsoft Academic Search

    F. Gagné; C. Blaise; C. André; M. Salazar

    2006-01-01

    The advent of global warming has given rise to the issue on how temperature impacts the susceptibility of ectothermic organisms to pollution. The purpose of this study was to examine the effects of pharmaceutical products and domestic wastewaters on temperature-dependent mitochondrial electron transport activity in the freshwater mussel Elliptio complanata. Mitochondria from mussels were freshly prepared and exposed to increasing

  13. Time-dependent transport through quantum-impurity systems with Kondo resonance

    NASA Astrophysics Data System (ADS)

    Cheng, YongXi; Hou, WenJie; Wang, YuanDong; Li, ZhenHua; Wei, JianHua; Yan, YiJing

    2015-03-01

    We investigate the time-dependent transport properties of single and double quantum-impurity systems based on the hierarchical equations of motion (HEOM) approach. In the Kondo regime, the dynamical current oscillates with time in both cases due to the temporal coherence of electrons tunneling through the device, which shares the same mechanism as the single-level resonance without e–e interactions, but shows some different characteristics. For single quantum-impurity systems, the temperature T has an inhibitory effect on the oscillations of dynamic current through its suppression of the Kondo effects. The amplitude of the current oscillations is attenuated by the e–e interaction U in the Kondo regime. The frequency of the current oscillations is found almost independent of T and U. For parallel-coupling double quantum-impurity systems, the oscillation of the current shows similar behavior to the single one, but with two-to-three times larger amplitudes. At the limit of small inter-impurity coupling the oscillation of the current exhibits enhanced characters, while it is weakened at the other limit.

  14. Cys(294) is essential for the function of the human sodium-dependent multivitamin transporter.

    PubMed

    Ghosal, Abhisek; Said, Hamid M

    2012-01-01

    The sodium-dependent multivitamin transporter (SMVT) plays an important role in biotin uptake in the intestine and other cell types. While significant knowledge has been gained with regard to regulation and cell biology of the SMVT system, there is little known about its structure-function relationships. Here we examined the role of each of the ten conserved (among species) cysteine residues in the function of the human SMVT (hSMVT) using site-directed mutagenesis. Our results showed a significant impairment in biotin uptake only in cells transfected with hSMVT mutated at Cys(294), but not at the other conserved cysteine residues; the impairment in biotin uptake caused by mutating Cys(294) was not related to the polar status of substituting amino acid. The inhibition in hSMVT function upon mutating Cys(294) was mediated via a significant reduction in the V(max), but not the apparent K(m), of the biotin uptake process, suggesting a decrease in the number (and/or activity) of hSMVT but not affinity. Biotinylation assay confirmed this suggestion by showing a marked reduction in the level of expression of the mutated protein at the cell membrane, without affecting total cellular level of induced hSMVT. These results show an important role for Cys(294) in the function and cell biology of hSMVT. PMID:22015582

  15. Composition-dependent structural and transport properties of amorphous transparent conducting oxides

    NASA Astrophysics Data System (ADS)

    Khanal, Rabi; Buchholz, D. Bruce; Chang, Robert P. H.; Medvedeva, Julia E.

    2015-05-01

    Structural properties of amorphous In-based oxides, In -X -O with X =Zn , Ga, Sn, or Ge, are investigated using ab initio molecular dynamics liquid-quench simulations. The results reveal that indium retains its average coordination of 5.0 upon 20% X fractional substitution for In, whereas X cations satisfy their natural coordination with oxygen atoms. This finding suggests that the carrier generation is primarily governed by In atoms, in accord with the observed carrier concentration in amorphous In-O and In -X -O . At the same time, the presence of X affects the number of six-coordinated In atoms as well as the oxygen sharing between the InO6 polyhedra. Based on the obtained interconnectivity and spatial distribution of the InO6 and XO x polyhedra in amorphous In -X -O , composition-dependent structural models of the amorphous oxides are derived. The results help explain our Hall mobility measurements in In -X -O thin films grown by pulsed-laser deposition and highlight the importance of long-range structural correlations in the formation of amorphous oxides and their transport properties.

  16. Temperature and force dependence of nanoscale electron transport via the Cu protein azurin.

    PubMed

    Li, Wenjie; Sepunaru, Lior; Amdursky, Nadav; Cohen, Sidney R; Pecht, Israel; Sheves, Mordechai; Cahen, David

    2012-12-21

    Solid-state electron transport (ETp) via a monolayer of immobilized azurin (Az) was examined by conducting probe atomic force microscopy (CP-AFM), as a function of both temperature (248-373K) and applied tip force (6-15 nN). At low forces, ETp via holo-Az (with Cu(2+)) is temperature-independent, but thermally activated via the Cu-depleted form of Az, apo-Az. While this observation agrees with those of macroscopic-scale measurements, we find that for holo-Az the mechanism of ETp at high temperatures changes upon an increase in the force applied by the tip to the proteins; namely, above 310 K and forces >6 nN ETp becomes thermally activated. This is in contrast to apo-Az, where increasing applied force causes only small monotonic increases in currents due to decreased electrode separation. The distinct ETp temperature dependence of holo- and apo-Az is assigned to a difference in structural response to pressure between the two protein forms. An important implication of these CP-AFM results (of measurements over a significant temperature range) is that for reliable ETp measurements on flexible macromolecules, such as proteins, the pressure applied during the measurements should be controlled or at least monitored. PMID:23136937

  17. Spin-dependent transport in a ZnMnO /ZnO heterostructure

    NASA Astrophysics Data System (ADS)

    Masuko, K.; Ashida, A.; Yoshimura, T.; Fujimura, N.

    2008-04-01

    We report a spin-dependent transport property in modulation-doped ZnMnO :Al/ZnMnO/ZnO heterostructures. Using ZnO (0001¯) single crystal substrates, the heterostructures with atomically smooth surface and interface were prepared. For the sample with the Mn concentration of 12at.%, the electron confinement at the ZnMnO /ZnO interface was recognized, indicating that ZnMnO layer acted as a barrier layer. In this paper, we investigated if an s-d exchange interaction exists between s electron conducting in the ZnO channel layer and Mn d spin in the ZnMnO barrier layer at the interface. To eliminate the Lorentz force and weak localization effects from the magnetoresistance (MR), the MR was measured under the magnetic field parallel to the sample surface. For a ZnMnO /ZnO heterostructure with the sheet carrier concentration of 5.46×1012cm-2, at 1.85K, the parallel-field MR revealed that a positive MR was dominant below 0.8T, while a negative MR was recognized above 0.8T. The positive MR was well fitted to a Brillouin function, suggesting the existence of an s-d exchange interaction at the ZnMnO /ZnO interface. The effect of the sheet carrier concentration on the MR behavior was also discussed.

  18. Solvent-type-dependent polymorphism and charge transport in a long fused-ring organic semiconductor.

    PubMed

    Chen, Jihua; Shao, Ming; Xiao, Kai; Rondinone, Adam J; Loo, Yueh-Lin; Kent, Paul R C; Sumpter, Bobby G; Li, Dawen; Keum, Jong K; Diemer, Peter J; Anthony, John E; Jurchescu, Oana D; Huang, Jingsong

    2014-01-01

    Crystalline polymorphism of organic semiconductors is among the critical factors in determining the structure and properties of the resultant organic electronic devices. Herein we report for the first time a solvent-type-dependent polymorphism of a long fused-ring organic semiconductor and its crucial effects on charge transport. A new polymorph of 5,11-bis(triethylsilylethynyl)anthradithiophene (TES ADT) is obtained using solvent-assisted crystallization, and the crystalline polymorphism of TES ADT thin films is correlated with their measured hole mobilities. The best-performing organic thin film transistors of the two TES ADT polymorphs show subthreshold slopes close to 1 V dec(-1), and threshold voltages close to zero, indicating that the density of traps at the semiconductor-dielectric interface is negligible in these devices and the observed up to 10-fold differences in hole mobilities of devices fabricated with different solvents are largely resultant from the presence of two TES ADT polymorphs. Moreover, our results suggest that the best-performing TES ADT devices reported in the literature correspond to the new polymorph identified in this study, which involves crystallization from a weakly polar solvent (such as toluene and chloroform). PMID:24217182

  19. MGS MAG/ER Data Analysis Using a Time and Magnetic Field Dependent Electron Transport Model

    NASA Technical Reports Server (NTRS)

    Liemohn, Michael W.; Mitchell, David L.; Nagy, A. F.

    2004-01-01

    The goal of that project was to examine certain details about the dayside electron environment at Mars as seen by the Mars Global Surveyor (MGS) magnetometer/electron reflectometer (MAG/ER) instrument. Specifically, we stated that we would use the Khazanov and Liemohn (K&L) kinetic electron transport model to analyze features in the observations. This code includes a non-uniform magnetic field and time-dependence in the result (different from most other models of this type). It was originally developed for electron motion along field lines in the Earth's magnetosphere (between conjugate ionospheres), and is thus quite appropriate for application to the Mars magnetic field scenario. Numerous code developments were implemented and the Mars version of the K&L model is fully operational. Initial results from this code have focused on the examination of MGS MAG/ER observations in the crustal field region when it is on the dayside. After several presentations at scientific meetings, this study culminated in a JGR publication last year.

  20. A specific pharmacophore model of sodium-dependent glucose co-transporter 2 (SGLT2) inhibitors.

    PubMed

    Tang, Chunlei; Zhu, Xiaoyun; Huang, Dandan; Zan, Xin; Yang, Baowei; Li, Ying; Du, Xiaoyong; Qian, Hai; Huang, Wenlong

    2012-06-01

    Sodium-dependent glucose co-transporter 2 (SGLT2) plays a pivotal role in maintaining glucose equilibrium in the human body, emerging as one of the most promising targets for the treatment of diabetes mellitus type 2. Pharmacophore models of SGLT2 inhibitors have been generated with a training set of 25 SGLT2 inhibitors using Discovery Studio V2.1. The best hypothesis (Hypo1(SGLT2)) contains one hydrogen bond donor, five excluded volumes, one ring aromatic and three hydrophobic features, and has a correlation coefficient of 0.955, cost difference of 68.76, RMSD of 0.85. This model was validated by test set, Fischer randomization test and decoy set methods. The specificity of Hypo1(SGLT2) was evaluated. The pharmacophore features of Hypo1(SGLT2) were different from the best pharmacophore model (Hypo1(SGLT1)) of SGLT1 inhibitors we developed. Moreover, Hypo1(SGLT2) could effectively distinguish selective inhibitors of SGLT2 from those of SGLT1. These results indicate that a highly predictive and specific pharmacophore model of SGLT2 inhibitors has been successfully obtained. Then Hypo1(SGLT2) was used as a 3D query to screen databases including NCI and Maybridge for identifying new inhibitors of SGLT2. The hit compounds were subsequently subjected to filtering by Lipinski's rule of five. And several compounds selected from the top ranked hits have been suggested for further experimental assay studies. PMID:22120948

  1. Neoclassical and gyrokinetic analysis of time-dependent helium transport experiments on MAST

    NASA Astrophysics Data System (ADS)

    Henderson, S. S.; Garzotti, L.; Casson, F. J.; Dickinson, D.; Fox, M. F. J.; O'Mullane, M.; Patel, A.; Roach, C. M.; Summers, H. P.; Valovi?, M.; The MAST Team

    2014-09-01

    Time-dependent helium gas puff experiments have been performed on the Mega Ampère Spherical Tokamak (MAST) during a two point plasma current scan in L-mode and a confinement scan at 900 kA. An evaluation of the He II (n = 4 ? 3) spectrum line induced by charge exchange suggests anomalous rates of diffusion and inward convection in the outer regions of both L-mode plasmas. Similar rates of diffusion are found in the H-mode plasma, however these rates are consistent with neoclassical predictions. The anomalous inward pinch found in the core of L-mode plasmas is also not apparent in the H-mode core. Linear gyrokinetic simulations of one flux surface in L-mode using the GS2 and GKW codes find that equilibrium flow shear is sufficient to stabilize ITG modes, consistent with beam emission spectroscopy (BES) observations, and suggest that collisionless TEMs may dominate the anomalous helium particle transport. A quasilinear estimate of the dimensionless peaking factor associated with TEMs is in good agreement with experiment. Collisionless TEMs are more stable in H-mode because the electron density gradient is flatter. The steepness of this gradient is therefore pivotal in determining the inward neoclassical particle pinch and the particle flux associated with TEM turbulence.

  2. Beam energy dependence of azimuthal anisotropy at RHIC-PHENIX

    SciTech Connect

    Taranenko, A., E-mail: arkadij@rcf.rhic.bnl.gov [Stony Brook University, Department of Chemistry (United States)

    2012-05-15

    Recent PHENIX measurements of the elliptic ({upsilon}{sub 2}) and hexadecapole ({upsilon}{sub 4}) Fourier flow coefficients for charged hadrons as a function of transverse momentum (p{sub T}), collision centrality and particle species are presented and compared with results from the PHOBOS and STAR Collaborations respectively. The status of extensions to future PHENIX measurements at lower beam energies is also discussed.

  3. Triple- and Quadruple-Gluon Azimuthal Correlations from Glasma and Higher-Dimensional Ridges

    E-print Network

    Sener Ozonder

    2015-02-11

    We calculate the triple- and quadruple-gluon inclusive distributions with arbitrary rapidity and azimuthal angle dependences in the gluon saturation regime by using glasma diagrams. Also, we predict higher-dimensional ridges in triple- and quadruple-hadron correlations for p-p and p-Pb collisions at LHC, which have yet to be measured. In p-p and p-Pb collisions at the top LHC energies, gluon saturation is expected to occur since smaller Bjorken-$x$ values are being probed. Glasma diagrams, which are enhanced at small-$x$, include the gluon saturation effects, and they are used for calculating the long-range rapidity correlations ("ridges") and $v_n$ moments of the azimuthal distribution of detected hadrons. The glasma description reproduces the systematics of the data on both p-p and p-Pb ridges. As an alternative, relativistic hydrodynamics has also been applied to these small systems quite successfully. With the triple- and quadruple-gluon azimuthal correlations, this work aims to set the stage by going beyond the double-gluon azimuthal correlations in order to settle unambiguously the origin of "collectivity" in p-p and p-Pb collisions. We derive the triple- and quadruple-gluon azimuthal correlation functions in terms of unintegrated gluon distributions at arbitrary rapidities and azimuthal angles of the produced gluons. Then, unintegrated gluon distributions from the running coupling Balitsky-Kovchegov evolution equation are used to calculate the triple- and quadruple-gluon correlations for various parameters of gluon momenta, initial scale for small-$x$ evolution and beam energy.

  4. Unmagnetized diffusion for azimuthally symmetric wave and particle distributions

    NASA Technical Reports Server (NTRS)

    Dusenbery, P. B.; Lyons, L. R.

    1988-01-01

    The quasi-linear diffusion of particles from resonant interactions with a spectrum of electrostatic waves is investigated theoretically, extending results obtained for no magnetic field and for strong magnetic fields to cases where the ambient magnetic field which organizes azimuthally symmetric wave and particle distributions does not have to be taken into consideration in evaluating the local interaction. The derivation of the governing equations is explained, and numerical results are presented in extensive graphs and characterized in detail. Slow-mode ion-acoustic waves are shown to be unstable under the plasma conditions studied, and the dependence of resonant-ion diffusion rates with pitch angle, speed, and the distribution of wave energy in wavenumber space is explored. The implications of the present findings for theoretical models of the earth bow shock and plasma-sheet boundary layer are indicated.

  5. Azimuthal asymmetries in the unpolarized SIDIS cross section at COMPASS

    E-print Network

    Giulio Sbrizzai for the COMPASS Collaboration

    2011-01-24

    The study of the spin structure of the nucleon and of the effects rising from the quarks transverse momentum are part of the scientific program of COMPASS, a fixed target experiment at the CERN SPS. The azimuthal asymmetries which appear in the cross-section of SIDIS off unpolarized targets can give insights on the intrinsic momentum structure of the nucleon and on the possible correlation between transverse spin and transverse momentum of the quarks. Here we present the new results for these asymmetries obtained from the COMPASS data collected with a 160 GeV/c positive muon beam impinging on a $^6LiD$ target. The asymmetries are measured for both positive and negative hadrons, and their dependence on several kinematical variable has been studied

  6. Line width dependence of transport properties in graphene nanoribbon interconnects with real space edge roughness determined by Monte Carlo method

    NASA Astrophysics Data System (ADS)

    Misawa, Taichi; Okanaga, Takuya; Mohamad, Aizuddin; Sakai, Tadashi; Awano, Yuji

    2015-05-01

    We developed a novel Monte Carlo simulation model to investigate the line width dependence of the transport properties of multi-layered graphene nanoribbon (GNR) interconnects with edge roughness. We reported that the line width dependence of carrier mobility decreases significantly as the magnitude of the edge roughness gets smaller, which agrees well with experiments. We also discussed the influence of the inelasticity of edge roughness scatterings, inter-layer tunneling, and line width dependent band structures on the line width of the GNR interconnects.

  7. Optimization of azimuth angle settings in polarizer-compensator-sample-analyzer off-null ellipsometry.

    PubMed

    Wang, Guoliang; Arwin, Hans; Jansson, Roger

    2003-01-01

    The dependence of the azimuth angle settings on the change in off-null intensity of a polarizer-compensator-sample-analyzer ellipsometer owing to changes in sample properties is studied. First, a closed-form expression for the relationship between azimuth angles that fulfill the null condition is presented. An approximation for the off-null light intensity near null that is valid for small changes of the p- and s-reflection coefficients of an isotropic sample is then derived. This approximation shows that the intensity change near the null can be described by changes in the ellipsometric parameters tan phi and A only. Expressions for finding the azimuth angle that gives the maximum possible intensity change for a given change in the sample parameters are also derived. The importance of optimization of azimuth angle settings for different samples is investigated and found to depend on tan psi. Numerical and experimental results chosen from the investigation of gas sensors based on porous silicon are included to verify the approximations as well as the optimization. PMID:12518821

  8. An improved reflectometric method to measure the azimuthal anchoring energy of nematic liquid crystals.

    PubMed

    Faetti, S; Mutinati, G C

    2003-03-01

    Some years ago we developed an automatized reflectometric method to measure the surface azimuthal anchoring energy of nematic liquid crystals on an optically isotropic substrate. This method provides a high accuracy and sensitivity but requires the use of wedge glass plates and a sufficiently high anisotropy of the intensity reflectivity coefficients. This latter condition restricts greatly the number of possible substrates that can be investigated with this technique. Here we develop a new reflectometric method which offers comparable or better accuracy and sensitivity but does not require wedge plates and high anisotropy of the reflectivity coefficients. The method is fully automated and provides a direct measurement of the azimuthal director angle. The experimental procedure exploits the dependence of the reflectivity tensor on the surface director orientation. The measurement of the azimuthal angle does not require any knowledge of the optical parameters of the nematic material and of the optically isotropic substrate, and provides an absolute accuracy better than 0.2( degrees ) in the whole range 0-360( degrees ) and a sensitivity better than 0.1( degrees ). This reflectometric method can be also used with weakly anisotropic substrates as well as thin rubbed polymeric layers. In this latter case, the effective uncertainty in the measurement of the director azimuthal angle depends on the substrate anisotropy. A simple and direct experimental procedure to estimate this uncertainty is proposed. PMID:15015108

  9. Cloning in Escherichia coli K-12 of a Na+-dependent transport system from a marine bacterium.

    PubMed

    MacLeod, P R; MacLeod, R A

    1986-03-01

    The transport of D-alanine by Escherichia coli K-12 neither requires nor is stimulated by Na+. The transport of D-alanine by the marine bacterium Alteromonas haloplanktis 214 requires Na+ specifically. Mutants of E. coli which were unable to transport D-alanine were isolated by enrichment for D-cycloserine resistance. One of the mutants was transformed with a gene bank of A. haloplanktis chromosomal DNA. Two transformants, E. coli RM1(pPM1) and E. coli RM1(pPM2) were able to transport D-alanine by a Na+-dependent mechanism. Li+ and K+ were unable to replace Na+. Both transformants contained chimeric plasmids with inserts which hybridized with A. haloplanktis but not E. coli chromosomal DNA or each other. Despite the lack of homology between the inserts, Na+-dependent D-alanine transport in the two transformants could not be distinguished either by kinetic studies or by differences in the capacity of various amino acids to compete for D-alanine uptake. PMID:3512524

  10. The blood-brain barrier sodium-dependent multivitamin transporter: a molecular functional in vitro-in situ correlation.

    PubMed

    Park, Seonghee; Sinko, Patrick J

    2005-10-01

    The molecular mechanism of biotin brain uptake was investigated using an in vitro bovine blood-brain barrier (BBB) cell model and an in situ mouse brain perfusion technique. A functional uptake/transport correlation of the in vitro and in situ characteristics of biotin uptake was investigated. Morphological and immunochemical characteristics (e.g., factor VIII expression) of the primary culture of brain microvessel endothelial cells (BMECs) were confirmed. Gene expression of the multidrug resistance (Mdr1) and sodium-dependent multivitamin (SMVT) transporters was also determined in BMECs. Biotin transport was saturable and Na(+)-dependent at the luminal side of the BBB. The estimated half-saturation concentrations (K(m)) of biotin uptake in vitro and in situ were 49.1 and 35.5 microM, respectively, supporting the presence of a carrier-mediated biotin transport system. Inhibition studies using various biotin derivatives and structural analogs demonstrated the structural requirements for biotin-SMVT interaction. Desthiobiotin and pantothenic acid significantly inhibited the uptake of biotin, whereas 2-iminobiotin and diaminobiotin were very weak inhibitors. Based on our results, there was a good correlation between the in vitro and in situ BBB models, suggesting that when a single membrane transporter is involved in substrate uptake, flexibility in choosing the experimental model can be afforded. The current results are also consistent with the suggestion that the properties of the BBB are likely to be organ-specific rather than species-specific. Further mechanistic and comparative studies are needed to validate these results. In conclusion, the in vitro transporter-based mechanism studies produced valuable molecular functional transport results that correlated well with in situ results. PMID:16033951

  11. A two-dimensional, time-dependent model of suspended sediment transport and bed reworking for continental shelves

    USGS Publications Warehouse

    Harris, C.K.; Wiberg, P.L.

    2001-01-01

    A two-dimensional, time-dependent solution to the transport equation is formulated to account for advection and diffusion of sediment suspended in the bottom boundary layer of continental shelves. This model utilizes a semi-implicit, upwind-differencing scheme to solve the advection-diffusion equation across a two-dimensional transect that is configured so that one dimension is the vertical, and the other is a horizontal dimension usually aligned perpendicular to shelf bathymetry. The model calculates suspended sediment concentration and flux; and requires as input wave properties, current velocities, sediment size distributions, and hydrodynamic sediment properties. From the calculated two-dimensional suspended sediment fluxes, we quantify the redistribution of shelf sediment, bed erosion, and deposition for several sediment sizes during resuspension events. The two-dimensional, time-dependent approach directly accounts for cross-shelf gradients in bed shear stress and sediment properties, as well as transport that occurs before steady-state suspended sediment concentrations have been attained. By including the vertical dimension in the calculations, we avoid depth-averaging suspended sediment concentrations and fluxes, and directly account for differences in transport rates and directions for fine and coarse sediment in the bottom boundary layer. A flux condition is used as the bottom boundary condition for the transport equation in order to capture time-dependence of the suspended sediment field. Model calculations demonstrate the significance of both time-dependent and spatial terms on transport and depositional patterns on continental shelves. ?? 2001 Elsevier Science Ltd. All rights reserved.

  12. Efficiency improvement of organic light-emitting diodes depending on the thickness variation of BCP layer used for electron transport

    Microsoft Academic Search

    Won-Jong Kim; Hyun-Min Choi; Joung-Sik Kim; Tae-Wan Kim; Jin-Woong Hong

    2009-01-01

    In the devices structure of ITO\\/N, N'-diphenyl-N, N'bis(3-methylphenyl)-1, 1'-biphenyl-4, 4'-diamine (TPD)\\/tris(8-hydroxyquinoline)aluminum (Alq3) electron-transport-layer (ETL) (2, 9-Dimethyl-4), 7-diphenyl-1, 10-phenanthroline (BCP))\\/Al, we have studied the efficiency improvement of organic light-emitting diodes depending on the thickness variation of BCP using electron transport layer. The thickness of TPD and Alq3 was manufactured 40 nm, 60 nm under a base pressure of 5 times 10-6

  13. Association of PDZ-containing protein PDZD11 with the human sodium-dependent multivitamin transporter.

    PubMed

    Nabokina, Svetlana M; Subramanian, Veedamali S; Said, Hamid M

    2011-04-01

    Intestinal absorption of biotin is mediated via the sodium-dependent multivitamin transporter (SMVT). Studies from our laboratory and others have characterized different aspects of the human SMVT (hSMVT), but nothing is currently known about protein(s) that may interact with hSMVT and affect its physiology/biology. In this study, a PDZ-containing protein PDZD11 was identified as an interacting partner with hSMVT using yeast two-hybrid screen of a human intestinal cDNA library. The interaction between hSMVT and PDZD11 was confirmed by in vitro GST-pull-down assay and in vivo in a mammalian cell environment by a two-hybrid luciferase and coimmunoprecipitation assays. Furthermore, confocal imaging of live human intestinal epithelial HuTu-80 cells expressing hSMVT-GFP and DsRed-PDZD11 demonstrated colocalization of these two proteins. We also examined the functional consequence of the interaction between hSMVT and PDZD11 in HuTu-80 cells and observed significant induction in [(3)H]biotin uptake upon coexpression of hSMVT and PDZD11. In contrast, knocking down of PDZD11 with gene-specific small interfering RNA led to a significant decrease in biotin uptake; biotinylation assay showed this to be associated with a marked decrease in level of expression of hSMVT at the cell membrane. By truncation approach, we also demonstrated that the PDZ binding domain that is located in the COOH-terminal tail of hSMVT polypeptide is involved in the interaction with PDZD11. These results demonstrate for the first time that PDZD11 is an interacting partner with hSMVT in intestinal epithelial cells and that this interaction affects hSMVT function and cell biology. PMID:21183659

  14. Computational Models for Drug Inhibition of the Human Apical Sodium-dependent Bile Acid Transporter

    PubMed Central

    Zheng, Xiaowan; Ekins, Sean; Raufman, Jean-Pierre; Polli, James E.

    2009-01-01

    The human apical sodium-dependent bile acid transporter (ASBT; SLC10A2) is the primary mechanism for intestinal bile acid re-absorption. In the colon, secondary bile acids increase the risk of cancer. Therefore, drugs that inhibit ASBT have the potential to increase the risk of colon cancer. The objectives of this study were to identify FDA-approved drugs that inhibit ASBT and to derive computational models for ASBT inhibition. Inhibition was evaluated using ASBT-MDCK monolayers and taurocholate as the model substrate. Computational modeling employed a HipHop qualitative approach, a Hypogen quantitative approach, as well as a modified Laplacian Bayesian modeling method using 2D descriptors. Initially, 30 compounds were screened for ASBT inhibition. A qualitative pharmacophore was developed using the most potent 11 compounds and applied to search a drug database, yielding 58 hits. Additional compounds were tested and their Ki values were measured. A 3D-QSAR and a Bayesian model were developed using 38 molecules. The quantitative pharmacophore consisted of one hydrogen bond acceptor, three hydrophobic features, and five excluded volumes. Each model was further validated with two external test sets of 30 and 19 molecules. Validation analysis showed both models exhibited good predictability in determining whether a drug is a potent or non-potent ASBT inhibitor. The Bayesian model correctly ranked the most active compounds. In summary, using a combined in vitro and computational approach, we found that many FDA-approved drugs from diverse classes, such as the dihydropyridine calcium channel blockers and HMG CoA-reductase inhibitors, are ASBT inhibitors. PMID:19673539

  15. Computational models for drug inhibition of the human apical sodium-dependent bile acid transporter.

    PubMed

    Zheng, Xiaowan; Ekins, Sean; Raufman, Jean-Pierre; Polli, James E

    2009-01-01

    The human apical sodium-dependent bile acid transporter (ASBT; SLC10A2) is the primary mechanism for intestinal bile acid reabsorption. In the colon, secondary bile acids increase the risk of cancer. Therefore, drugs that inhibit ASBT have the potential to increase the risk of colon cancer. The objectives of this study were to identify FDA-approved drugs that inhibit ASBT and to derive computational models for ASBT inhibition. Inhibition was evaluated using ASBT-MDCK monolayers and taurocholate as the model substrate. Computational modeling employed a HipHop qualitative approach, a Hypogen quantitative approach, and a modified Laplacian Bayesian modeling method using 2D descriptors. Initially, 30 compounds were screened for ASBT inhibition. A qualitative pharmacophore was developed using the most potent 11 compounds and applied to search a drug database, yielding 58 hits. Additional compounds were tested, and their K(i) values were measured. A 3D-QSAR and a Bayesian model were developed using 38 molecules. The quantitative pharmacophore consisted of one hydrogen bond acceptor, three hydrophobic features, and five excluded volumes. Each model was further validated with two external test sets of 30 and 19 molecules. Validation analysis showed both models exhibited good predictability in determining whether a drug is a potent or nonpotent ASBT inhibitor. The Bayesian model correctly ranked the most active compounds. In summary, using a combined in vitro and computational approach, we found that many FDA-approved drugs from diverse classes, such as the dihydropyridine calcium channel blockers and HMG CoA-reductase inhibitors, are ASBT inhibitors. PMID:19673539

  16. Azimuthal field instability in a confined ferrofluid.

    PubMed

    Dias, Eduardo O; Miranda, José A

    2015-02-01

    We report the development of interfacial ferrohydrodynamic instabilities when an initially circular bubble of a nonmagnetic inviscid fluid is surrounded by a viscous ferrofluid in the confined geometry of a Hele-Shaw cell. The fluid-fluid interface becomes unstable due to the action of magnetic forces induced by an azimuthal field produced by a straight current-carrying wire that is normal to the cell plates. In this framework, a pattern formation process takes place through the interplay between magnetic and surface tension forces. By employing a perturbative mode-coupling approach we investigate analytically both linear and intermediate nonlinear regimes of the interface evolution. As a result, useful analytical information can be extracted regarding the destabilizing role of the azimuthal field at the linear level, as well as its influence on the interfacial pattern morphology at the onset of nonlinear effects. Finally, a vortex sheet formalism is used to access fully nonlinear stationary solutions for the two-fluid interface shapes. PMID:25768610

  17. Azimuthal field instability in a confined ferrofluid

    NASA Astrophysics Data System (ADS)

    Dias, Eduardo O.; Miranda, José A.

    2015-02-01

    We report the development of interfacial ferrohydrodynamic instabilities when an initially circular bubble of a nonmagnetic inviscid fluid is surrounded by a viscous ferrofluid in the confined geometry of a Hele-Shaw cell. The fluid-fluid interface becomes unstable due to the action of magnetic forces induced by an azimuthal field produced by a straight current-carrying wire that is normal to the cell plates. In this framework, a pattern formation process takes place through the interplay between magnetic and surface tension forces. By employing a perturbative mode-coupling approach we investigate analytically both linear and intermediate nonlinear regimes of the interface evolution. As a result, useful analytical information can be extracted regarding the destabilizing role of the azimuthal field at the linear level, as well as its influence on the interfacial pattern morphology at the onset of nonlinear effects. Finally, a vortex sheet formalism is used to access fully nonlinear stationary solutions for the two-fluid interface shapes.

  18. TOPSAR data focusing based on azimuth scaling preprocessing

    NASA Astrophysics Data System (ADS)

    Xu, Wei; Huang, Pingping; Deng, Yunkai

    2011-07-01

    Both Doppler spectral aliasing and azimuth output time folding simultaneously exist in TOPSAR (Terrain Observation by Progressive Scans) raw data. Resampling in both Doppler frequency and azimuth time domain can resolve the azimuth aliasing problem but with the seriously increased computational complexity and memory consumption. According to the special characteristics of TOPSAR raw data support in the slow time/frequency domain (TFD), the presented azimuth scaling preprocessing step is introduced to not only resolve the Doppler spectral aliasing problem but also reduce the increased azimuth samples. Furthermore, the correction of sawtoothed azimuth antenna pattern (AAP) becomes easy to be implemented. The following conventional stripmap processor can be adopted to focus the residual TOPSAR raw data but with the result of azimuth aliased TOPSAR image. The mosaic approach, which has been presented to unfold azimuth aliased ScanSAR image, is exploited to resolve the problem of azimuth output folding in TOPSAR mode. Simulation results and pulse response parameters are given to validate the presented imaging approach.

  19. Dependence of transport rate on area of lithography and pretreatment of tip in dip-pen nanolithography.

    PubMed

    Wu, Tzu-Heng; Lu, Hui-Hsin; Lin, Chii-Wann

    2012-10-16

    This study examines the lithographic capacity of tips in dip-pen nanolithography (DPN). The dependence of the transport rate (R) decay on the area of lithography (A(lith)), the dependence of A(lith) on the lithographic time (t), and the effect of piranha cleaning on the lithographic capacity are considered herein. The dependencies in the line-drawing lithography process are studied using 16-mercaptohexadecanoic acid (MHA) ink. On the basis of the linear decay dependence discovered in the R-A(lith) dependence, piranha treatment can increase the lithographic capacity by up to 35.5-fold, an improvement that may originate from a change in the tip's surface chemistry. Moreover, a theoretical model is derived to describe the A(lith)-t dependence accurately and to predict the tips' lifetime. Furthermore, an experiment involving DPN-based nanostructure fabrication demonstrates the importance of monitoring the tips' transport rate and lifetime. In addition to shedding light on the physical and chemical principles behind DPN, this study provides a comprehensive model for a quantitative analysis of the tips' behavior. PMID:23020585

  20. Scale dependence of sorption coefficients for contaminant transport in saturated fractured rock

    Microsoft Academic Search

    Zhenxue Dai; Andrew Wolfsberg; Zhiming Lu; Hailin Deng

    2009-01-01

    A significant challenge in contaminant transport modeling is to obtain a mechanistic understanding of transport parameter scaling that accurately addresses the combined influence of physical and chemical heterogeneities at different scales. In this paper, we have developed a scaling methodology to upscale matrix sorption coefficients for fractured-rock systems by characterizing both the tortuosity field (physical heterogeneity) and retardation factor field

  1. Mutations in the Caenorhabditis elegans Serotonin Reuptake Transporter MOD-5 Reveal Serotonin-Dependent and -Independent

    E-print Network

    Horvitz, H. Robert

    Mutations in the Caenorhabditis elegans Serotonin Reuptake Transporter MOD-5 Reveal Serotonin the only sero- tonin reuptake transporter (SERT) in C. elegans. The selective serotonin reuptake inhibitor; fluoxetine; serotonin; reuptake; modulation of behavior; SSRI The activity of serotonin (5-HT), a key

  2. Temperature dependence of electron transport in GaN\\/AlGaN quantum cascade detectors

    Microsoft Academic Search

    Sergii V. Gryshchenko; Mykhaiol V. Klymenko; Vladimir V. Lysak; Olexiy V. Shulika; Igor A. Sukhoivanov

    2011-01-01

    In this work we investigate the influence of extractor design and temperature on transport properties of quantum cascade detector. For this purpose we realize numerical calculation of electron lifetimes considering electronphonon and electron impurities scattering. Electron-phonon interactions are treated using Fermi Golden Rule which allows to calculate lifetime of carriers with temperature and structure design taking into account. Transport characteristics

  3. Global Upper Mantle Azimuthal Anisotropy From Probabilistic Tomography

    NASA Astrophysics Data System (ADS)

    Beghein, C.; Yuan, K.

    2014-12-01

    The new model of Yuan and Beghein (2013), hereafter YBaniSV13, is the first global model to constrain 3-D azimuthal anisotropy in the deep upper mantle. It is compatible with previous models in the uppermost 200km of the mantle, but also displays 1% anisotropy above, inside, and below the Mantle Transition Zone (MTZ). Another interesting characteristic of this model is the change in fast seismic direction detected, on average, at ~250km depth and at the MTZ boundaries. These results have important consequences for our understanding of mantle deformation and convection patterns in the mantle. It is therefore important to assess the robustness if these features. We already tested that the model does not strongly depend on the reference 1-D mantle model, on the presence of discontinuities in this reference model, or on the crustal model and Moho depth used to calculate the laterally varying partial derivatives. In this work, we apply a model space approach, the Neighborhood Algorithm (NA) of Sambridge (1999), to determine quantitative model uncertainties and parameter trade-offs. First, the NA generates an ensemble of models with a sampling density that increases toward the best fitting regions of the model space, and then performs a Bayesian appraisal of the models obtained that allows us to determine the likelihood of azimuthal anisotropy in different region of Earth's interior. Such approaches have the advantage of sampling the model null-space, and therefore provide more reliable model uncertainties than traditional inverse techniques. We use YBaniSV13 as initial model, and search the model space around it, allowing for large enough deviations to test the robustness of the anisotropy amplitude. We compare results from a model space search based on the chi-square misfit and from a model space search based on the variance reduction, which is another useful measure of data fit that is independent of data uncertainties. Preliminary results for the chi-square driven search show that most likely model that is close to YBaniSV13, but uncertainties are rather large even in the shallow mantle where azimuthal anisotropy is usually considered to be well-resolved.

  4. OPTIMAL DESIGN OF DEPENDABLE AUTOMATED SYSTEM ARCHITECTURES APPLICATION TO A RAILROAD TRANSPORTATION SYSTEM

    Microsoft Academic Search

    Clarhaut Joffrey

    Designing a dependable automated system needs accurate methods to evaluate efficiently the dependability level of one given component architecture. This evaluation is crucial in order to determine the risks associated with system failures and the remaining properties after the fault occurrence. The dependability level of an automated system depends not only on the kind of component failures that may occur

  5. Contact metal-dependent electrical transport in carbon nanotubes and fabrication of graphene nanoribbons

    NASA Astrophysics Data System (ADS)

    Perello, David

    In this thesis, we fabricate and characterize carbon nanotube (CNT) and graphene-based field effect transistor devices. The CNT-based work centers around the physics of metal contacts to CNT, particularly relating the work function of contact metals to carrier transport across the junction. The graphene work is motivated by the desire to utilize the high carrier mobility of graphene in field effect transistors. CNT have excellent electrical properties including high carrier mobility, large field effect switching capabilities, and a long mean free path. Absent, however is an experimentally-backed model explaining contact-metal work function, device layout, and environment effects. To fill this void, we introduce a surface-inversion channel (SIC) model based on low temperature and electrical measurements of a distinct single-walled semiconducting CNT contacted by Hf, Cr, Ti and Pd electrodes. Anomalous barrier heights and metal-contact dependent band-to-band tunneling phenomena are utilized to show that dependent upon contact work function and gate field, transport occurs either directly between the metal and CNT channel or indirectly via injection of carriers from the metal-covered CNT region to the CNT channel. The model is consistent with previously contradictory experimental results, and the methodology is simple enough to apply in other contact-dominant systems. In agreement with the initial contact theory above, we further develop a model explain Isd-Vsd tendencies in CNT FETs. Using experimental and analytical analysis, we demonstrate a relationship between the contact metal work function and electrical transport properties saturation current (Isat) and differential conductance ssd=6Isd 6Vsd in ambient exposed CNT. A single chemical vapor deposition (CVD)-grown 6 millimeter long semiconducting single-walled CNT is electrically contacted with a statistically significant number of Hf, Cr, Ti, Pd, and Ti, Au electrodes, respectively. The observed exponentially increasing relationship of I sat and sigmasd with metal-contact work function that is explained by a theoretical model derived from thermionic field emission. Statistical analysis and spread of the data suggest that the conduction variability in same-CNT devices results from differences in local surface potential of the metal contact. Based on the theoretical model and methodology, an improved CNT-based gas sensing device layout is suggested; a method to experimentally determine gas-induced work function changes in metals is also proposed. Third, a performance analysis on CNT Schottky diodes using source-drain current anisotropy is explored. An analytical model is derived based on thermionic field emission and used to correlate experimental data from Pd-Hf, Ti-Hf, Cr-Hf, Ti-Cr, and Pd-Au mixed metal devices fabricated on one single 6 mm-long CNT. Results suggest that the difference in work functions of the two contact-metals, and not a dominant Schottky contact, determines diode performance. Results are further applied and demonstrated in a reversible polarity diode. Next, we develop experimental processes to grow high quality monolayer graphene on Cu foil. Cu foil is pre-annealed and hand polished to increase Cu crystalline domain size and reduce surface roughness. This is done to reduce nucleation sites for graphene during CVD growth. After growth on Cu foil, the graphene is transferred to SiO2 using a floating PMMA method described in section 3.2.2. Finally, the quality of the graphene is analyzed via Raman spectroscopy, optical imagery, and sheet resistance measurements. After demonstrating the quality of the graphene film, we investigate the effect of UV irradiation of graphene, CNT, and graphene/CNT hybrids in an oxygen environment. Samples were irradiated by 254/185 nm UV light in an oxygen environment for up to two hours. Results suggest a unique method to generate graphene nanoribbons using aligned carbon nanotubes (CNT) as a graphene etch mask. Ambient and cryogenic Gsd-Vg measurements of resulting ultrathin graphene nanoribbons show p-type character an

  6. Membrane targeting and intracellular trafficking of the human sodium-dependent multivitamin transporter in polarized epithelial cells.

    PubMed

    Subramanian, Veedamali S; Marchant, Jonathan S; Boulware, Michael J; Ma, Thomas Y; Said, Hamid M

    2009-04-01

    The human sodium-dependent multivitamin transporter (hSMVT) mediates sodium-dependent uptake of biotin in renal and intestinal epithelia. To date, however, there is nothing known about the structure-function relationship or targeting sequences in the hSMVT polypeptide that control its polarized expression within epithelia. Here, we focused on the role of the COOH-terminal tail of hSMVT in the targeting and functionality of this transporter. A full-length hSMVT-green fluorescent protein (GFP) fusion protein was functional and expressed at the apical membrane in renal and intestinal cell lines. Microtubule disrupting agents disrupted the mobility of trafficking vesicles and impaired cell surface delivery of hSMVT, which was also prevented in cells treated with dynamitin (p50), brefeldin, or monensin. Progressive truncation of the COOH-terminal tail impaired the functionality and targeting of the transporter. First, biotin transport decreased by approximately 20-30% on deletion of up to 15 COOH-terminal amino acids of hSMVT, a decrease mimicked solely by deletion of the terminal PDZ motif (TSL). Second, deletions into the COOH-terminal tail (between residues 584-612, containing a region of predicted high surface accessibility) resulted in a further drop in hSMVT transport (to approximately 40% of wild-type). Third, apical targeting was lost on deletion of a helical-prone region between amino acids 570-584. We conclude that the COOH tail of hSMVT contains several determinants important for polarized targeting and biotin transport. PMID:19211916

  7. Discriminating top-antitop resonances using azimuthal decay correlations

    NASA Astrophysics Data System (ADS)

    Baumgart, Matthew; Tweedie, Brock

    2011-09-01

    Top-antitop pairs produced in the decay of a new heavy resonance will exhibit spin correlations that contain valuable coupling information. When the tops decay, these correlations imprint themselves on the angular patterns of the final quarks and leptons. While many approaches to the measurement of top spin correlations are known, the most common ones require detailed kinematic reconstructions and are insensitive to some important spin interference effects. In particular, spin-1 resonances with mostly-vector or mostly-axial couplings to top cannot be easily discriminated from one another without appealing to mass-suppressed effects or to more model-dependent interference with continuum Standard Model production. Here, we propose to probe the structure of a resonance's couplings to tops by measuring the azimuthal angles of the tops' decay products about the production axis. These angles exhibit modulations which are typically O(0.1-1), and which by themselves allow for discrimination of spin-0 from higher spins, measurement of the CP-phase for spin-0, and measurement of the vector/axial composition for spins1and 2. For relativistic tops, the azimuthal decay angles can be well-approximated without detailed knowledge of the tops' velocities, and appear to be robust against imperfect energy measurements and neutrino reconstructions. We illustrate this point in the highly challenging dileptonic decay mode, which also exhibits the largest modulations. We comment on the relevance of these observables for testing axigluon-like models that explain the top quark A FB anomaly at the Tevatron, through direct production at the LHC.

  8. Regulation of energy partitioning and alternative electron transport pathways during cold acclimation of lodgepole pine is oxygen dependent.

    PubMed

    Savitch, Leonid V; Ivanov, Alexander G; Krol, Marianna; Sprott, David P; Oquist, Gunnar; Huner, Norman P A

    2010-09-01

    Second year needles of Lodgepole pine (Pinus contorta L.) were exposed for 6 weeks to either simulated control summer ['summer'; 25 °C/250 photon flux denisty (PFD)], autumn ('autumn'; 15°C/250 PFD) or winter conditions ('winter'; 5 °C/250 PFD). We report that the proportion of linear electron transport utilized in carbon assimilation (ETR(CO2)) was 40% lower in both 'autumn' and 'winter' pine when compared with the 'summer' pine. In contrast, the proportion of excess photosynthetic linear electron transport (ETR(excess)) not used for carbon assimilation within the total ETR(Jf) increased by 30% in both 'autumn' and 'winter' pine. In 'autumn' pine acclimated to 15°C, the increased amounts of 'excess' electrons were directed equally to 21 ?kPa O2-dependent and 2 ?kPa O2-dependent alternative electron transport pathways and the fractions of excitation light energy utilized by PSII photochemistry (?(PSII)), thermally dissipated through ?(NPQ) and dissipated by additional quenching mechanism(s) (?(f,D)) were similar to those in 'summer' pine. In contrast, in 'winter' needles acclimated to 5 °C, 60% of photosynthetically generated 'excess' electrons were utilized through the 2 ?kPa O2-dependent electron sink and only 15% by the photorespiratory (21 ?kPa O2) electron pathway. Needles exposed to 'winter' conditions led to a 3-fold lower ?(PSII), only a marginal increase in ?(NPQ) and a 2-fold higher ?(f,D), which was O2 dependent compared with the 'summer' and 'autumn' pine. Our results demonstrate that the employment of a variety of alternative pathways for utilization of photosynthetically generated electrons by Lodgepole pine depends on the acclimation temperature. Furthermore, dissipation of excess light energy through constitutive non-photochemical quenching mechanisms is O2 dependent. PMID:20630988

  9. Azimuthal anchoring energy at the interface between a nematic liquid crystal and a PTFE substrate.

    PubMed

    Campanelli, E; Faetti, S; Nobili, M

    2003-06-01

    The azimuthal anchoring energy of the nematic liquid crystal 4-pentyl-4'-cyanobiphenil (5CB) on a poly(tetrafluoroethylene) (teflon, PTFE) film is measured for the first time. The PTFE film is deposed using the Wittmann and Smith technique which consists on rubbing a bar of this polymer against a glass substrate at a controlled temperature and pressure. Measurements of the azimuthal anchoring energy are made with a reflectometric technique which provides high accuracy and sensitivity. The dependence of the azimuthal anchoring energy on temperature and on the rubbing pressure is investigated. The extrapolation length remains virtually constant in the whole temperature range of the nematic phase except for an increase of 25% close to the clearing temperature. The azimuthal anchoring energy is somewhat strong and increases with increasing the deposition pressure of PTFE. The observation of a relevant pre-transitional anisotropy of the reflection coefficients in the isotropic phase proves that the surface interactions favor an excess of orientational order. Ageing of the anchoring energy and gliding of the easy axis are experimentally observed. Both these phenomena suggest the presence of an anisotropic adsorbed layer of nematic molecules on the PTFE film. PMID:15011060

  10. Role of proton hopping in surface charge transport on tin dioxide as revealed by the thermal dependence of conductance.

    PubMed

    Wexler, Robert B; Sohlberg, Karl

    2014-12-26

    The presence of water on an oxide surface can dramatically alter its electrical properties with important consequences for electrical measurements by scanning probe microscopy, and for the use of semiconducting oxides in sensing applications. Here, the thermal dependence of the conductance of tin dioxide is interpreted by combining semiconductor equilibrium carrier statistics with a proton hopping mechanism. First, the functional form of this charge transport model is fit to experimental conductance data for tin dioxide. Next, the important energy parameters in the model are computed with density functional theory. Comparing the values of the energy parameters obtained by fitting, to the values for the same parameters obtained from electronic structure calculations, yields new insight into the surface charge transport in tin dioxide. In particular, it is found that mobile protons, freed from the dissociative adsorption of water on the [110] surface, are an essential component of the observed thermal dependence of conductance in tin dioxide. PMID:25275726

  11. The role of water in surface charge transport on tin dioxide as revealed by the thermal dependence of conductance

    NASA Astrophysics Data System (ADS)

    Wexler, Robert; Sohlberg, Karl

    2013-03-01

    The presence of water on an oxide surface can dramatically alter its electrical properties with important consequences for electrical measurements by scanning probe microscopy, and for the use of semiconducting oxides in sensing applications. Here, the thermal dependence of the surface conductance of tin dioxide is interpreted by combining equilibrium carrier statistics with the Grotthuss mechanism for proton hopping. The functional form of this charge transport model is fit to experimental conductance data for tin dioxide. Next, the important energy parameters in the model are computed with electronic structure methods. Comparing the values of the energy parameters obtained by fitting to those obtained from electronic structure calculations yields new insight into the surface charge transport in tin dioxide. In particular, it is found that mobile protons, freed by the dissociative adsorption of water on the [110] surface, are an essential component of the observed thermal dependence of surface conductance in tin dioxide.

  12. Ca2+-dependent Calmodulin Binding to FcRn Affects Immunoglobulin G Transport in the Transcytotic Pathway

    PubMed Central

    Dickinson, Bonny L.; Claypool, Steven M.; D'Angelo, June A.; Aiken, Martha L.; Venu, Nanda; Yen, Elizabeth H.; Wagner, Jessica S.; Borawski, Jason A.; Pierce, Amy T.; Hershberg, Robert; Blumberg, Richard S.

    2008-01-01

    The Fc? receptor FcRn transports immunoglobulin G (IgG) so as to avoid lysosomal degradation and to carry it bidirectionally across epithelial barriers to affect mucosal immunity. Here, we identify a calmodulin-binding site within the FcRn cytoplasmic tail that affects FcRn trafficking. Calmodulin binding to the FcRn tail is direct, calcium-dependent, reversible, and specific to residues comprising a putative short amphipathic ?-helix immediately adjacent to the membrane. FcRn mutants with single residue substitutions in this motif, or FcRn mutants lacking the cytoplasmic tail completely, exhibit a shorter half-life and attenuated transcytosis. Chemical inhibitors of calmodulin phenocopy the mutant FcRn defect in transcytosis. These results suggest a novel mechanism for regulation of IgG transport by calmodulin-dependent sorting of FcRn and its cargo away from a degradative pathway and into a bidirectional transcytotic route. PMID:18003977

  13. Gibberellin regulates PIN-FORMED abundance and is required for auxin transport-dependent growth and development in Arabidopsis thaliana.

    PubMed

    Willige, Björn C; Isono, Erika; Richter, René; Zourelidou, Melina; Schwechheimer, Claus

    2011-06-01

    Plants integrate different regulatory signals to control their growth and development. Although a number of physiological observations suggest that there is crosstalk between the phytohormone gibberellin (GA) and auxin, as well as with auxin transport, the molecular basis for this hormonal crosstalk remains largely unexplained. Here, we show that auxin transport is reduced in the inflorescences of Arabidopsis thaliana mutants deficient in GA biosynthesis and signaling. We further show that this reduced auxin transport correlates with a reduction in the abundance of PIN-FORMED (PIN) auxin efflux facilitators in GA-deficient plants and that PIN protein levels recover to wild-type levels following GA treatment. We also demonstrate that the regulation of PIN protein levels cannot be explained by a transcriptional regulation of the PIN genes but that GA deficiency promotes, at least in the case of PIN2, the targeting of PIN proteins for vacuolar degradation. In genetic studies, we reveal that the reduced auxin transport of GA mutants correlates with an impairment in two PIN-dependent growth processes, namely, cotyledon differentiation and root gravitropic responses. Our study thus presents evidence for a role of GA in these growth responses and for a GA-dependent modulation of PIN turnover that may be causative for these differential growth responses. PMID:21642547

  14. Field-dependent critical state of high-Tc superconducting strip simultaneously exposed to transport current and perpendicular magnetic field

    SciTech Connect

    Xue, Cun; He, An; Yong, Huadong; Zhou, Youhe, E-mail: zhouyh@lzu.edu.cn [Key Laboratory of Mechanics on Disaster and Environment in Western China attached to the Ministry of Education of China, and Department of Mechanics and Engineering Sciences, College of Civil Engineering and Mechanics, Lanzhou University, Lanzhou, Gansu 730000 (China)] [Key Laboratory of Mechanics on Disaster and Environment in Western China attached to the Ministry of Education of China, and Department of Mechanics and Engineering Sciences, College of Civil Engineering and Mechanics, Lanzhou University, Lanzhou, Gansu 730000 (China)

    2013-12-15

    We present an exact analytical approach for arbitrary field-dependent critical state of high-T{sub c} superconducting strip with transport current. The sheet current and flux-density profiles are derived by solving the integral equations, which agree with experiments quite well. For small transport current, the approximate explicit expressions of sheet current, flux-density and penetration depth for the Kim model are derived based on the mean value theorem for integration. We also extend the results to the field-dependent critical state of superconducting strip in the simultaneous presence of applied field and transport current. The sheet current distributions calculated by the Kim model agree with experiments better than that by the Bean model. Moreover, the lines in the I{sub a}-B{sub a} plane for the Kim model are not monotonic, which is quite different from that the Bean model. The results reveal that the maximum transport current in thin superconducting strip will decrease with increasing applied field which vanishes for the Bean model. The results of this paper are useful to calculate ac susceptibility and ac loss.

  15. TIMEX: a time-dependent explicit discrete ordinates program for the solution of multigroup transport equations with delayed neutrons

    Microsoft Academic Search

    T. R. Hill; W. H. Reed

    1976-01-01

    TIMEX solves the time-dependent, one-dimensional multigroup transport equation with delayed neutrons in plane, cylindrical, spherical, and two-angle plane geometries. Both regular and adjoint, inhomogeneous and homogeneous problems subject to vacuum, reflective, periodic, white, albedo or inhomogeneous boundary flux conditions are solved. General anisotropic scattering is allowed and anisotropic inhomogeneous sources are permitted. The discrete ordinates approximation for the angular variable

  16. Spin-dependent transport in a nanopillar non-local spin valve J.-B. Laloe a,, T. Yang a

    E-print Network

    Otani, Yoshichika

    Spin-dependent transport in a nanopillar non-local spin valve J.-B. Lalo¨e a,Ã, T. Yang a , T: Lateral spin-valve Spin current a b s t r a c t We investigate the injection of a pure spin current into a non-magnetic Cu wire in a lateral spin valve. We detect the spin accumulation occurring

  17. Serotonin transporter polymorphism as a predictor for escitalopram treatment of major depressive disorder comorbid with alcohol dependence

    Microsoft Academic Search

    Leea H. Muhonen; Jari Lahti; Hannu Alho; Jouko Lönnqvist; Jari Haukka; Sirkku T. Saarikoski

    2011-01-01

    The aim of this study was to determine whether the serotonin transporter gene polymorphism (5-HTTLPR) is associated with the treatment outcomes of escitalopram for patients with comorbid major depression and alcohol dependence. Eighty treatment-seeking patients were randomly assigned to either receive 20mg of escitalopram or a control of 20mg of the non-serotonergically acting memantine. Depression was measured by the Montgomery–Asberg

  18. Sodium-dependent glucose transporter reduces peroxynitrite and cell injury caused by cisplatin in renal tubular epithelial cells

    Microsoft Academic Search

    Akira Ikari; Yoshiaki Nagatani; Mitsutoshi Tsukimoto; Hitoshi Harada; Masao Miwa; Kuniaki Takagi

    2005-01-01

    Cisplatin causes nephropathy accompanied by two types of cell death, necrosis and apoptosis, according to its dosage. The mechanisms of necrosis are still unclear. In this study, we examined how high doses of cisplatin induce cell injury and whether a high affinity sodium-dependent glucose transporter (SGLT1) has a cytoprotective function in renal epithelial LLC-PK1 cells. Cisplatin decreased in transepithelial electrical

  19. Protein translocation across the inner membrane of Gram-negative bacteria: the Sec and Tat dependent protein transport pathways.

    PubMed

    Kudva, Renuka; Denks, Kärt; Kuhn, Patrick; Vogt, Andreas; Müller, Matthias; Koch, Hans-Georg

    2013-01-01

    Gram negative bacteria possess a large variety of protein transport systems, by which proteins that are synthesised in the cytosol are exported to destinations in the cell envelope or entirely secreted into the extracellular environment. The inner membrane (IM) contains three major transport systems for the translocation and insertion of signal sequence containing proteins: the Sec translocon, the YidC insertase, and the Tat system. The heterotrimeric SecYEG translocon forms a narrow channel in the membrane that serves a dual function; it allows the translocation of unfolded proteins across the pore and the integration of ?-helical proteins into the IM. The YidC insertase is a multi-spanning membrane protein that cooperates with the SecYEG translocon during the integration of membrane proteins but also functions as an independent insertase. Depending upon the type of protein cargo that needs to be transported, the Signal Recognition Particle (SRP), the SRP receptor, SecA and chaperones are required to coordinate translation with transport and to target and energise the different transport systems. The Tat system consists of three membrane proteins (TatA, TatB and TatC) which in a still unknown manner accomplish the transmembrane passage of completely folded proteins and protein complexes. PMID:23567322

  20. The Concentration Dependence of Active Potassium Transport in the Human Red Blood Cell*

    PubMed Central

    Sachs, John R.; Welt, Louis G.

    1967-01-01

    The relation between the active potassium influx in the human red blood cell and the extracellular potassium concentration does not appear to be consistent with the Michaelis-Menten model, but is adequately described by a model in which two potassium ions are required simultaneously at some site or sites in the transport mechanism before transport occurs. The same type of relation appears to exist between that portion of the sodium outflux that requires the presence of extracellular potassium and the extracellular potassium concentration. Rubidium, cesium, and lithium, which are apparently transported by the same system that transports potassium, stimulate the potassium influx when both potassium and the second ion are present at low concentrations, as is predicted by the two-site model. PMID:6018751

  1. Frequency dependences in transport through a Tomonaga-Luttinger liquid wire

    Microsoft Academic Search

    V. V. Ponomarenko

    1996-01-01

    Dynamics of one-dimensional electron transport between two reservoirs are studied based on the inhomogeneous Tomonaga-Luttinger-liquid model in the case when the effect of the electron backscattering on the impurities is negligible. The inhomogeneities of the interaction lead to a charge-wave reflection. This effect supposes a special behavior of the transport characteristics at the microwave frequencies. Different features are predicted in

  2. Variable azimuthal anisotropy in Earth's lowermost mantle.

    PubMed

    Garnero, Edward J; Maupin, Valérie; Lay, Thorne; Fouch, Matthew J

    2004-10-01

    A persistent reversal in the expected polarity of the initiation of vertically polarized shear waves that graze the D'' layer (the layer at the boundary between the outer core and the lower mantle of Earth) in some regions starts at the arrival time of horizontally polarized shear waves. Full waveform modeling of the split shear waves for paths beneath the Caribbean requires azimuthal anisotropy at the base of the mantle. Models with laterally coherent patterns of transverse isotropy with the hexagonal symmetry axis of the mineral phases tilted from the vertical by as much as 20 degrees are consistent with the data. Small-scale convection cells within the mantle above the D'' layer may cause the observed variations by inducing laterally variable crystallographic or shape-preferred orientation in minerals in the D'' layer. PMID:15472071

  3. Variable Azimuthal Anisotropy in Earth's Lowermost Mantle

    NASA Astrophysics Data System (ADS)

    Garnero, Edward J.; Maupin, Valérie; Lay, Thorne; Fouch, Matthew J.

    2004-10-01

    A persistent reversal in the expected polarity of the initiation of vertically polarized shear waves that graze the D'' layer (the layer at the boundary between the outer core and the lower mantle of Earth) in some regions starts at the arrival time of horizontally polarized shear waves. Full waveform modeling of the split shear waves for paths beneath the Caribbean requires azimuthal anisotropy at the base of the mantle. Models with laterally coherent patterns of transverse isotropy with the hexagonal symmetry axis of the mineral phases tilted from the vertical by as much as 20° are consistent with the data. Small-scale convection cells within the mantle above the D'' layer may cause the observed variations by inducing laterally variable crystallographic or shape-preferred orientation in minerals in the D'' layer.

  4. VACUUM calculation in azimuthally symmetric geometry

    SciTech Connect

    Chance, M.S.

    1996-11-01

    A robustly accurate and effective method is presented to solve Laplace`s equation in general azimuthally symmetric geometry for the magnetic scalar potential in the region surrounding a plasma discharge which may or may not contain external conducting shells. These shells can be topologically toroidal or spherical, and may have toroidal gaps in them. The solution is incorporated into the various MHD stability codes either through the volume integrated perturbed magnetic energy in the vacuum region or through the continuity requirements for the normal component of the perturbed magnetic field and the total perturbed pressure across the unperturbed plasma-vacuum boundary. The method is based upon using Green`s second identity and the method of collocation. As useful byproducts, the eddy currents and the simulation of Mirnov loop measurements are calculated.

  5. Independent control of polar and azimuthal anchoring.

    PubMed

    Anquetil-Deck, C; Cleaver, D J; Bramble, J P; Atherton, T J

    2013-07-01

    Monte Carlo simulation, experiment, and continuum theory are used to examine the anchoring exhibited by a nematic liquid crystal at a patterned substrate comprising a periodic array of rectangles that, respectively, promote vertical and planar alignment. It is shown that the easy axis and effective anchoring energy promoted by such surfaces can be readily controlled by adjusting the design of the pattern. The calculations reveal rich behavior: for strong anchoring, as exhibited by the simulated system, for rectangle ratios ?2 the nematic aligns in the direction of the long edge of the rectangles, the azimuthal anchoring coefficient changing with pattern shape. In weak anchoring scenarios, however, including our experimental systems, preferential anchoring is degenerate between the two rectangle diagonals. Bistability between diagonally aligned and edge-aligned arrangement is predicted for intermediate combinations of anchoring coefficient and system length scale. PMID:23944468

  6. Effects of hearing protectors on auditory localization in azimuth and elevation.

    PubMed

    Bolia, R S; D'Angelo, W R; Mishler, P J; Morris, L J

    2001-01-01

    An experiment was conducted to determine the effects of two types of hearing protectors on auditory localization performance. Six listeners localized a 750-ms broadband noise from loudspeakers ranging in azimuth from -180 degrees to +180 degrees and in elevation from -75 degrees to +90 degrees. Independent variables included the type of hearing protector and the elevation of the source. Dependent measures included azimuth error, elevation error, and the percentage of trials resulting in a front-back confusion. Performance on each of the dependent measures was found to be mediated by one or more of the independent variables. Actual or potential applications include the generation of improved design guidelines for hearing protectors and workplace alarms. PMID:11474758

  7. A Stealthy Path Planning Method for Aircraft by Constant Azimuth

    Microsoft Academic Search

    Ling-Xiao Wang; De-Yun Zhou; Rui Zheng

    2010-01-01

    According to the characteristic of Radar Cross Section (RCS) of the aircraft and the Schematic graph of the radar range, Flight with certain constant azimuth can make the generic aircraft which does not have the ability of stealth eluding radars in battlefield. The form of spatial curve that the flying aircraft follows with constant azimuth is first proved, then the

  8. Azimuth Variation in Microwave Backscatter over the Greenland Ice Sheet

    E-print Network

    Long, David G.

    ice sheet (see Fig. 2). For each sen- sor, different day ranges were used. SeaWinds uses 2 daysAzimuth Variation in Microwave Backscatter over the Greenland Ice Sheet Ivan S. Ashcraft and David ice sheet. However, most Greenland studies assume constant backscatter for varying azimuth angles

  9. Computation of azimuthal combustion instabilities in an helicopter combustion chamber

    E-print Network

    Nicoud, Franck

    Computation of azimuthal combustion instabilities in an helicopter combustion chamber C. Sensiau to compute azimuthal combustion instabilities is presented. It requires a thermoacoustic model using a n - formulation for the coupling between acoutics and combustion. The parameters n and are computed from a LES

  10. Cloning and functional expression of a cDNA encoding a mammalian sodium-dependent vitamin transporter mediating the uptake of pantothenate, biotin, and lipoate.

    PubMed

    Prasad, P D; Wang, H; Kekuda, R; Fujita, T; Fei, Y J; Devoe, L D; Leibach, F H; Ganapathy, V

    1998-03-27

    Previous studies have shown that a Na+-dependent transport system is responsible for the transplacental transfer of the vitamins pantothenate and biotin and the essential metabolite lipoate. We now report the isolation of a rat placental cDNA encoding a transport protein responsible for this function. The cloned cDNA, when expressed in HeLa cells, induces Na+-dependent pantothenate and biotin transport activities. The transporter is specific for pantothenate, biotin, and lipoate. The Michaelis-Menten constant (Kt) for the transport of pantothenate and biotin in cDNA-transfected cells is 4.9 +/- 1.1 and 15.1 +/- 1.2 microM, respectively. The transport of both vitamins in cDNA-transfected cells is inhibited by lipoate with an inhibition constant (Ki) of approximately 5 microM. The nucleotide sequence of the cDNA (sodium-dependent multivitamin transporter (SMVT)) predicts a protein of 68.6 kDa with 634 amino acids and 12 potential transmembrane domains. Protein data base search indicates significant sequence similarity between SMVT and known members of the Na+-dependent glucose transporter family. Northern blot analysis shows that SMVT transcripts are present in all of the tissues that were tested. The size of the principal transcript is 3.2 kilobases. SMVT represents the first Na+-dependent vitamin transporter to be cloned from a mammalian tissue. PMID:9516450

  11. Feedback control of an azimuthal oscillation in the E Multiplication-Sign B discharge of Hall thrusters

    SciTech Connect

    Griswold, M. E.; Ellison, C. L.; Raitses, Y.; Fisch, N. J. [Princeton Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543 (United States)

    2012-05-15

    Feedback control of a low-frequency azimuthal wave known as a 'rotating spoke' in the E Multiplication-Sign B discharge of a cylindrical Hall thruster was demonstrated. The rotating spoke is an m = 1 azimuthal variation in density, electron temperature, and potential that rotates at about 10% of the local E Multiplication-Sign B electron rotation speed. It causes increased electron transport across the magnetic field and is suspected to be an ionization wave. Feedback control of this wave required special consideration because, although it causes a rotating azimuthal variation in the current density to the anode, it does not show up as a signal in the total thruster discharge current. Therefore, an extra source of information was needed to track the oscillation, which was addressed by using a special anode that was split azimuthally into four segments. The current to each segment oscillates as the rotating spoke passes over it, and feedback is accomplished by resistors connected in series with each anode segment which causes the voltage on a segment to decrease in proportion to the current through that segment. The feedback resulted in the disappearance of a coherent azimuthal wave and a decrease in the time-averaged total discharge current by up to 13.2%.

  12. Bicarbonate-dependent chloride transport drives fluid secretion by the human airway epithelial cell line Calu-3

    PubMed Central

    Shan, Jiajie; Liao, Jie; Huang, Junwei; Robert, Renaud; Palmer, Melissa L; Fahrenkrug, Scott C; O'Grady, Scott M; Hanrahan, John W

    2012-01-01

    Anion and fluid secretion are both defective in cystic fibrosis (CF); however, the transport mechanisms are not well understood. In this study, Cl? and HCO3? secretion was measured using genetically matched CF transmembrane conductance regulator (CFTR)-deficient and CFTR-expressing cell lines derived from the human airway epithelial cell line Calu-3. Forskolin stimulated the short-circuit current (Isc) across voltage-clamped monolayers, and also increased the equivalent short-circuit current (Ieq) calculated under open-circuit conditions. Isc was equivalent to the HCO3? net flux measured using the pH-stat technique, whereas Ieq was the sum of the Cl? and HCO3? net fluxes. Ieq and HCO3? fluxes were increased by bafilomycin and ZnCl2, suggesting that some secreted HCO3? is neutralized by parallel electrogenic H+ secretion. Ieq and fluid secretion were dependent on the presence of both Na+ and HCO3?. The carbonic anhydrase inhibitor acetazolamide abolished forskolin stimulation of Ieq and HCO3? secretion, suggesting that HCO3? transport under these conditions requires catalysed synthesis of carbonic acid. Cl? was the predominant anion in secretions under all conditions studied and thus drives most of the fluid transport. Nevertheless, 50–70% of Cl? and fluid transport was bumetanide-insensitive, suggesting basolateral Cl? loading by a sodium–potassium–chloride cotransporter 1 (NKCC1)-independent mechanism. Imposing a transepithelial HCO3? gradient across basolaterally permeabilized Calu-3 cells sustained a forskolin-stimulated current, which was sensitive to CFTR inhibitors and drastically reduced in CFTR-deficient cells. Net HCO3? secretion was increased by bilateral Cl? removal and therefore did not require apical Cl?/HCO3? exchange. The results suggest a model in which most HCO3? is recycled basolaterally by exchange with Cl?, and the resulting HCO3?-dependent Cl? transport provides an osmotic driving force for fluid secretion. PMID:22777674

  13. Regulation of Nitrate Transport in Citrus Rootstocks Depending on Nitrogen Availability

    PubMed Central

    Cerezo, Miguel; Camañes, Gemma; Flors, Víctor; Primo-Millo, Eduardo

    2007-01-01

    Previously, we reported that in Citrus plants, nitrate influx through the plasmalemma of roots cells follows a biphasic pattern, suggesting the existence of at least two different uptake systems, a high and low affinity transport system (HATS and LATS, respectively). Here, we describe a novel inducible high affinity transport system (iHATS). This new nitrate transport system has a high capacity to uptake nitrate in two different Citrus rootstocks (Cleopatra mandarin and Troyer citrange). The iHATS was saturable, showing higher affinity than constitutive high affinity transport system (cHATS) to the substrate NO3?. The Vmax for this saturable component iHATS was higher than cHATS, reaching similar values in both rootstocks. Additionally, we studied the regulation of root NO3? uptake mediated by both HATS (iHATS and cHATS) and LATS. In both rootstocks, cHATS is constitutive and independent of N-status. Concerning the regulation of iHATS, this system is upregulated by NO3? and down-regulated by the N status and by NO3? itself when plants are exposed to it for a longer period of time. LATS in Cleopatra mandarin and Troyer citrange rootstocks is repressed by the N-status. The use of various metabolic uncouplers or inhibitors indicated that NO3? net uptake mediated by iHATS and LATS was an active transport system in both rootstocks. PMID:19516998

  14. Phosphorylation-regulated axonal dependent transport of syntaxin 1 is mediated by a Kinesin-1 adapter.

    PubMed

    Chua, John Jia En; Butkevich, Eugenia; Worseck, Josephine M; Kittelmann, Maike; Grønborg, Mads; Behrmann, Elmar; Stelzl, Ulrich; Pavlos, Nathan J; Lalowski, Maciej M; Eimer, Stefan; Wanker, Erich E; Klopfenstein, Dieter Robert; Jahn, Reinhard

    2012-04-10

    Presynaptic nerve terminals are formed from preassembled vesicles that are delivered to the prospective synapse by kinesin-mediated axonal transport. However, precisely how the various cargoes are linked to the motor proteins remains unclear. Here, we report a transport complex linking syntaxin 1a (Stx) and Munc18, two proteins functioning in synaptic vesicle exocytosis at the presynaptic plasma membrane, to the motor protein Kinesin-1 via the kinesin adaptor FEZ1. Mutation of the FEZ1 ortholog UNC-76 in Caenorhabditis elegans causes defects in the axonal transport of Stx. We also show that binding of FEZ1 to Kinesin-1 and Munc18 is regulated by phosphorylation, with a conserved site (serine 58) being essential for binding. When expressed in C. elegans, wild-type but not phosphorylation-deficient FEZ1 (S58A) restored axonal transport of Stx. We conclude that FEZ1 operates as a kinesin adaptor for the transport of Stx, with cargo loading and unloading being regulated by protein kinases. PMID:22451907

  15. Fluoride-dependent interruption of the transport cycle of a CLC Cl?/H+ antiporter

    PubMed Central

    Lim, Hyun-Ho; Stockbridge, Randy B.; Miller, Christopher

    2013-01-01

    Cl?/H+ antiporters of the CLC superfamily transport anions across biological membranes in varied physiological contexts. These proteins are weakly selective among anions commonly studied, including Cl?, Br?, I?,NO3?, and SCN?, but appear to be very selective against F?. The recent discovery of a new CLC clade of F?/H+ antiporters, which are highly selective for F? over Cl?, led us to investigate the mechanism of Cl?-over-F? selectivity by a CLC Cl?/H+ antiporter, CLC-ec1. By subjecting purified CLC-ec1 to anion transport measurements, electrophysiological recording, equilibrium ligand-binding studies, and x-ray crystallography, we show that F? binds in the Cl? transport pathway with affinity similar to Cl?, but stalls the transport cycle. Examination of various mutant antiporters implies a “lock-down” mechanism of F? inhibition, in which F?, by virtue of its unique H-bonding chemistry, greatly retards a proton-linked conformational change essential for the transport cycle of CLC-ec1. PMID:24036509

  16. Forward-backward correlations between multiplicities in windows separated in azimuth and rapidity

    E-print Network

    Vladimir Vechernin

    2014-10-24

    The forward-backward (FB) charged particle multiplicity correlations between windows separated in rapidity and azimuth are analyzed using a model that treats strings as independent identical emitters. Both the short-range (SR) contribution, originating from the correlation between multiplicities produced from a single source, and the long-range (LR) contribution, originating from the fluctuation in the number of sources, are taken into account. The dependencies of the FB correlation coefficient, $b$, on the windows' rapidity and azimuthal acceptance and the gaps between these windows are studied and compared with the preliminary data of ALICE. The analysis of these dependencies effectively separates the contributions of two above mechanisms. It is also demonstrated that traditional definitions of FB correlation coefficient $b$ have a strong nonlinear dependence on the acceptance of windows. Suitable alternative observables for the future FB correlation studies are proposed. The connection between $b$ and the two-particle correlation function, $C_2$, is traced, as well as its connection to the untriggered di-hadron correlation analysis. Using a model independent analysis, it is shown that measurement of the FB multiplicity correlations between two small windows separated in rapidity and azimuth fully determine the two-particle correlation function $C_2$, even if the particle distribution in rapidity is not uniform.

  17. Forward-backward correlations between multiplicities in windows separated in azimuth and rapidity

    NASA Astrophysics Data System (ADS)

    Vechernin, Vladimir

    2015-07-01

    The forward-backward (FB) charged particle multiplicity correlations between windows separated in rapidity and azimuth are analyzed using a model that treats strings as independent identical emitters. Both the short-range (SR) contribution, originating from the correlation between multiplicities produced from a single source, and the long-range (LR) contribution, originating from the fluctuation in the number of sources, are taken into account. The dependencies of the FB correlation coefficient, b, on the windows' rapidity and azimuthal acceptance and the gaps between these windows are studied and compared with the preliminary data of ALICE. The analysis of these dependencies effectively separates the contributions of two above mechanisms. It is also demonstrated that traditional definitions of FB correlation coefficient b have a strong nonlinear dependence on the acceptance of windows. Suitable alternative observables for the future FB correlation studies are proposed. The connection between b and the two-particle correlation function, C2, is traced, as well as its connection to the untriggered di-hadron correlation analysis. Using a model independent analysis, it is shown that measurement of the FB multiplicity correlations between two small windows separated in rapidity and azimuth fully determines the two-particle correlation function C2, even if the particle distribution in rapidity is not uniform.

  18. Analyses of azimuthal seismic anisotrophy in the vertically fractured Spraberry and Dean formations, Midland County, Texas 

    E-print Network

    Sudarmo, Bernadus Supraptomo

    1993-01-01

    The configuration of a CDP gather from 3-D seismic reflection has source-receiver pairs located at different azimuths. This can be exploited to observe azimuthal variations of P- wave velocity related to azimuthal anisotropy ...

  19. Zinc transporter ZnT-3 regulates presynaptic Erk1/2 signaling and hippocampus-dependent memory

    PubMed Central

    Sindreu, Carlos; Palmiter, Richard D.; Storm, Daniel R.

    2011-01-01

    The physiological role of vesicular zinc at central glutamatergic synapses remains poorly understood. Here we show that mice lacking the synapse-specific vesicular zinc transporter ZnT3 (ZnT3KO mice) have reduced activation of the Erk1/2 MAPK in hippocampal mossy fiber terminals, disinhibition of zinc-sensitive MAPK tyrosine phosphatase activity, and impaired MAPK signaling during hippocampus-dependent learning. Activity-dependent exocytosis is required for the effect of zinc on presynaptic MAPK and phosphatase activity. ZnT3KO mice have complete deficits in contextual discrimination and spatial working memory. Local blockade of zinc or MAPK in the mossy fiber pathway of wild-type mice impairs contextual discrimination. We conclude that ZnT3 is important for zinc homeostasis modulating presynaptic MAPK signaling and is required for hippocampus-dependent memory. PMID:21245308

  20. Azimuthal anisotropy in U+U collisions at STAR

    DOE PAGESBeta

    Wang, Hui; Sorensen, Paul

    2014-12-01

    The azimuthal anisotropy of particle production is commonly used in high-energy nuclear collisions to study the early evolution of the expanding system. The prolate shape of uranium nuclei makes it possible to study how the geometry of the colliding nuclei affects #12;final state anisotropies. It also provides a unique opportunity to understand how entropy is produced in heavy ion collisions. In this paper, the two- and four- particle cumulant v2 (v2{2} and v2{4}) from U+U collisions at ?sNN = 193 GeV and Au+Au collisions at ?sNN = 200 GeV for inclusive charged hadrons will be presented. The STAR Zero Degreemore »Calorimeters are used to select very central collisions. Differences were observed between the multiplicity dependence of v2{2} for most central Au+Au and U+U collisions. The multiplicity dependence of v2{2} in central collisions were compared to Monte Carlo Glauber model predictions and it was seen that this model cannot explain the present results. (auth)« less

  1. Azimuthal anisotropy in U+U collisions at STAR

    E-print Network

    Hui Wang; Paul Sorensen

    2014-06-29

    The azimuthal anisotropy of particle production is commonly used in high-energy nuclear collisions to study the early evolution of the expanding system. The prolate shape of uranium nuclei makes it possible to study how the geometry of the colliding nuclei affects final state anisotropies. It also provides a unique opportunity to understand how entropy is produced in heavy ion collisions. In this paper, the two- and four- particle cumulant $v_2$ ($v_{2}\\{2\\}$ and $v_{2}\\{4\\}$) from U+U collisions at $\\sqrt{s_{NN}}$ = 193 GeV and Au+Au collisions at $\\sqrt{s_{NN}}$ = 200 GeV for inclusive charged hadrons will be presented. The STAR Zero Degree Calorimeters are used to select very central collisions. Differences were observed between the multiplicity dependence of $v_{2}\\{2\\}$ for most central Au+Au and U+U collisions. The multiplicity dependence of $v_{2}\\{2\\}$ in central collisions were compared to Monte Carlo Glauber model predictions and it was seen that this model cannot explain the present results.

  2. Azimuthal anisotropy in U+U collisions at STAR

    DOE PAGESBeta

    Wang, Hui; Sorensen, Paul

    2014-12-01

    The azimuthal anisotropy of particle production is commonly used in high-energy nuclear collisions to study the early evolution of the expanding system. The prolate shape of uranium nuclei makes it possible to study how the geometry of the colliding nuclei affects #12;final state anisotropies. It also provides a unique opportunity to understand how entropy is produced in heavy ion collisions. In this paper, the two- and four- particle cumulant v2 (v2{2} and v2{4}) from U+U collisions at ?sNN = 193 GeV and Au+Au collisions at ?sNN = 200 GeV for inclusive charged hadrons will be presented. The STAR Zero Degree Calorimeters are used to select very central collisions. Differences were observed between the multiplicity dependence of v2{2} for most central Au+Au and U+U collisions. The multiplicity dependence of v2{2} in central collisions were compared to Monte Carlo Glauber model predictions and it was seen that this model cannot explain the present results. (auth)

  3. Temperature dependence of spin-polarized transport in ferromagnet\\/unconventional superconductor junctions

    Microsoft Academic Search

    T. Hirai; Y. Tanaka; N. Yoshida; Y. Asano; J. Inoue; S. Kashiwaya

    2003-01-01

    Tunneling conductance in ferromagnet\\/unconventional superconductor junctions is studied theoretically as a function of temperature and spin polarization in ferromagnets. In d-wave superconductor junctions, a zero-energy Andreev bound state drastically affects the temperature dependence of the zero-bias conductance (ZBC). In p-wave superconductor junctions, numerical results show various temperature dependences of the ZBC depending on the direction of the magnetic moment in

  4. Dimensionality-dependent charge transport in close-packed nanoparticle arrays: from 2D to 3D.

    PubMed

    Wang, Ying; Duan, Chao; Peng, Lianmao; Liao, Jianhui

    2014-01-01

    Charge transport properties in close-packed nanoparticle arrays with thickness crossing over from two dimensions to three dimensions have been studied. The dimensionality transition of nanoparticle arrays was realized by continually printing spatially well-defined nanoparticle monolayers on top of the device in situ. The evolution of charge transport properties depending on the dimensionality has been investigated in both the Efros-Shaklovskii variable-range-hopping (ES-VRH) (low temperature) regime and the sequential hopping (SH) (medium temperature) regime. We find that the energy barriers to transport decrease when the thickness of nanoparticle arrays increases from monolayer to multilayers, but start to level off at the thickness of 4-5 monolayers. The energy barriers are characterized by the coefficient ?D at ES-VRH regime and the activation energy Ea at SH regime. Moreover, a turning point for the temperature coefficient of conductance was observed in multilayer nanoparticle arrays at high temperature, which is attributed to the increasing mobility with decreasing temperature of hopping transport in three dimensions. PMID:25523836

  5. Deformationally dependent fluid transport properties of porcine coronary arteries based on location in the coronary vasculature

    PubMed Central

    Keyes, Joseph T.; Lockwood, Danielle R.; Simon, Bruce R.; Vande Geest, Jonathan P.

    2013-01-01

    Objective Understanding coronary artery mass transport allows researchers to better comprehend how drugs or proteins move through, and deposit into, the arterial wall. Characterizing how the convective component of transport changes based on arterial location could be useful to better understand how molecules distribute in different locations in the coronary vasculature. Methods and results We measured the mechanical properties and wall fluid flux transport properties of de-endothelialized (similar to post-stenting or angioplasty) left anterior descending (LADC) and right (RC) porcine coronary arteries along their arterial lengths. Multiphoton microscopy was used to determine microstructural differences. Proximal LADC regions had a higher circumferential stiffness than all other regions. Permeability decreased by 198% in the LADC distal region compared to other LADC regions. The RC artery showed a decrease of 46.9% from the proximal to middle region, and 51.7% from the middle to distal regions. The porosity increased in the intima between pressure states, without differences through the remainder of the arterial thickness. Conclusions We showed that the permeabilities and mechanical properties do vary in the coronary vasculature. With variations in mechanical properties, overexpansion of stents can occur more easily while variations in permeability may lead to altered transport based on location. PMID:23127633

  6. Coupled Factors Influencing Concentration Dependent Colloid Transport and Retention in Saturated Porous Media

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The coupled influence of input suspension concentration (Ci), ionic strength (IS) and hydrodynamics on the transport and retention of 1.1 'm carboxyl modified latex colloids in saturated quartz sand (150 'm) was investigated. Results from batch experiments and interaction energy calculations indica...

  7. Modeling of Time-dependent Radial Transport of Electron Distribution Perturbations Caused by ECCD in DIII-D

    SciTech Connect

    Harvey, R. W. [CompX, P.O. Box 2672, Del Mar, CA, 92014 (United States); Prater, R.; Petty, C. C. [General Atomics, San Diego, CA 92186-5608 (United States)

    2007-09-28

    In strongly driven ECCD experiments, consideration of radial transport can be crucial for accurate modeling of otherwise localized electron cyclotron current drive. The DIII-D experiment is in an intermediate driven regime with t{sub transport}{approx}t{sub slowing} for the EC driven electrons. We report computational results from the CQL3D Fokker-Planck simulation code showing radial spreading of driven ECCD in DIII-D. Progress on implementation of a new iterative sparse matrix fully-implicit solve for the full 3D electron distribution, f(u,{theta}{sub u},{rho},t) and toroidal electric potential, V{sub loop({rho},t)} is described. We give a new algorithm for implicit determination of the self-consistent solution of the Ampere-Faraday equation for the time-dependent toroidal electric field.

  8. Cell-cycle-dependent regulation of CNT1, a concentrative nucleoside transporter involved in the uptake of cell-cycle-dependent nucleoside-derived anticancer drugs.

    PubMed

    Valdés, Raquel; Casado, F Javier; Pastor-Anglada, Marçal

    2002-08-23

    Most nucleoside-derived anticancer drugs are taken up by the high-affinity Na-dependent nucleoside transporter CNT1. Since such drugs are to some extent cell-cycle-dependent in their cytotoxic action, we examined the relationship between CNT1 expression and cell-cycle progression in the rat hepatoma cell line FAO. Cell cultures were synchronized either at late G1 or early S stages by combining mimosin treatment with either previous synchronization or not by serum starvation. Cell-cycle progression was then assessed by measuring [methyl-3H]thymidine incorporation into DNA and monitoring cyclin E and A protein levels. In these conditions, CNT1 protein amounts increase at the G1-S transition. When cells were synchronized using hydroxyurea (HU), which directly interacts with nucleotide metabolism by inhibiting ribonucleotide reductase, CNT1 protein amounts increased in synchronized cells and remained high during cell-cycle progression. These data indicate that CNT1 adapts to cell-cycle progression and responds to nucleos(t)ide metabolism status, a feature that might contribute to the cytotoxic action of cell-cycle-dependent anticancer drugs. PMID:12176019

  9. Spin-dependent transport behavior in C60 and Alq3 based spin valves with a magnetite electrode (invited)

    NASA Astrophysics Data System (ADS)

    Zhang, Xianmin; Mizukami, Shigemi; Ma, Qinli; Kubota, Takahide; Oogane, Mikihiko; Naganuma, Hiroshi; Ando, Yasuo; Miyazaki, Terunobu

    2014-05-01

    The spin-dependent transport behavior in organic semiconductors (OSs) is generally observed at low temperatures, which likely results from poor spin injection efficiency at room temperature from the ferromagnetic metal electrodes to the OS layer. Possible reasons for this are the low Curie temperature and/or the small spin polarization efficiency for the ferromagnetic electrodes used in these devices. Magnetite has potential as an advanced candidate for use as the electrode in spintronic devices, because it can achieve 100% spin polarization efficiency in theory, and has a high Curie temperature (850 K). Here, we fabricated two types of organic spin valves using magnetite as a high efficiency electrode. C60 and 8-hydroxyquinoline aluminum (Alq3) were employed as the OS layers. Magnetoresistance ratios of around 8% and over 6% were obtained in C60 and Alq3-based spin valves at room temperature, respectively, which are two of the highest magnetoresistance ratios in organic spin valves reported thus far. The magnetoresistance effect was systemically investigated by varying the thickness of the Alq3 layer. Moreover, the temperature dependence of the magnetoresistance ratios for C60 and Alq3-based spin valves were evaluated to gain insight into the spin-dependent transport behavior. This study provides a useful method in designing organic spin devices operated at room temperature.

  10. Azimuthal distributions of charged hadrons, pions, and kaons produced in deep-inelastic scattering off unpolarized protons and deuterons

    NASA Astrophysics Data System (ADS)

    Airapetian, A.; Akopov, N.; Akopov, Z.; Aschenauer, E. C.; Augustyniak, W.; Avakian, R.; Avetissian, A.; Avetisyan, E.; Belostotski, S.; Blok, H. P.; Borissov, A.; Bowles, J.; Bryzgalov, V.; Burns, J.; Capiluppi, M.; Cisbani, E.; Ciullo, G.; Contalbrigo, M.; Dalpiaz, P. F.; Deconinck, W.; De Leo, R.; De Nardo, L.; De Sanctis, E.; Diefenthaler, M.; Di Nezza, P.; Düren, M.; Elbakian, G.; Ellinghaus, F.; Fantoni, A.; Felawka, L.; Frullani, S.; Gapienko, G.; Gapienko, V.; Garibaldi, F.; Gavrilov, G.; Gharibyan, V.; Giordano, F.; Gliske, S.; Golembiovskaya, M.; Hadjidakis, C.; Hartig, M.; Hasch, D.; Hillenbrand, A.; Hoek, M.; Holler, Y.; Hristova, I.; Imazu, Y.; Ivanilov, A.; Jackson, H. E.; Jo, H. S.; Joosten, S.; Kaiser, R.; Karyan, G.; Keri, T.; Kinney, E.; Kisselev, A.; Korotkov, V.; Kozlov, V.; Kravchenko, P.; Krivokhijine, V. G.; Lagamba, L.; Lapikás, L.; Lehmann, I.; Lenisa, P.; López Ruiz, A.; Lorenzon, W.; Ma, B.-Q.; Mahon, D.; Makins, N. C. R.; Manaenkov, S. I.; Manfré, L.; Mao, Y.; Marianski, B.; Martinez de la Ossa, A.; Marukyan, H.; Miller, C. A.; Miyachi, Y.; Movsisyan, A.; Murray, M.; Nappi, E.; Naryshkin, Y.; Nass, A.; Negodaev, M.; Nowak, W.-D.; Pappalardo, L. L.; Perez-Benito, R.; Petrosyan, A.; Raithel, M.; Reimer, P. E.; Reolon, A. R.; Riedl, C.; Rith, K.; Rosner, G.; Rostomyan, A.; Rubin, J.; Ryckbosch, D.; Salomatin, Y.; Sanftl, F.; Schäfer, A.; Schnell, G.; Schüler, K. P.; Seitz, B.; Shibata, T.-A.; Stancari, M.; Statera, M.; Steijger, J. J. M.; Stewart, J.; Stinzing, F.; Terkulov, A.; Truty, R. M.; Trzcinski, A.; Tytgat, M.; Vandenbroucke, A.; Van Haarlem, Y.; Van Hulse, C.; Veretennikov, D.; Vikhrov, V.; Vilardi, I.; Wang, S.; Yaschenko, S.; Ye, Z.; Yen, S.; Yu, W.; Zagrebelnyy, V.; Zeiler, D.; Zihlmann, B.; Zupranski, P.

    2013-01-01

    The azimuthal cos?? and cos?2? modulations of the distribution of hadrons produced in unpolarized semi-inclusive deep-inelastic scattering of electrons and positrons off hydrogen and deuterium targets have been measured in the HERMES experiment. For the first time these modulations were determined in a four-dimensional kinematic space for positively and negatively charged pions and kaons separately, as well as for unidentified hadrons. These azimuthal dependences are sensitive to the transverse motion and polarization of the quarks within the nucleon via, e.g., the Cahn, Boer-Mulders and Collins effects.

  11. Na(+)- and Cl(-)-dependent neurotransmitter transporters in bovine retina: identification and localization by in situ hybridization histochemistry.

    PubMed

    Jones, E M

    1995-01-01

    The physiological actions of biogenic amine and amino-acid neurotransmitters are terminated by their removal from the synaptic cleft by specific high-affinity transport proteins. The members of the Na(+)- and Cl(-)-dependent neurotransmitter transporter family expressed in bovine retina and responsible for the uptake of biogenic amine and amino-acid neurotransmitters were identified using a reverse transcriptase-polymerase chain reaction-based approach. cDNA clones encoding bovine homologues of glycine (GLYT-1), gamma-aminobutyric acid (GAT-1), creatine (CreaT), and orphan (NTT4) transporters were identified using this strategy. The expression pattern of mRNAs encoding these proteins in the retina was determined by in situ hybridization histochemistry. GLYT-1, CreaT, NTT4, and GAT-1 mRNAs were expressed in the retina by cells in the inner nuclear, inner plexiform, and ganglion cell layers. They were not expressed at detectable levels in the photoreceptor cells whose cell bodies are in the outer nuclear layer and are the most abundant cell type in the retina. GLYT-1 mRNA was present exclusively in the proximal inner nuclear layer. GAT-1 mRNA was localized to both the inner nuclear and ganglion cell layers. CreaT mRNA was expressed in all cell types in the retina, except photoreceptors, and NTT4 mRNA was expressed by a subpopulation of cells in the ganglion cell layer. Elucidation of the expression pattern of these neurotransmitter transporter mRNAs in the retina provides a basis for studies of the role of glycine, gamma-aminobutyric acid, and creatine transporters in retinal function. PMID:8962832

  12. Non-monotonic temperature dependent transport in graphene grown by Chemical Vapor Deposition

    Microsoft Academic Search

    J. Heo; H. J. Chung; Sung-Hoon Lee; H. Yang; D. H. Seo; J. K. Shin; U-In Chung; S. Seo; E. H. Hwang; S. Das Sarma

    2010-01-01

    Temperature-dependent resistivity of graphene grown by chemical vapor\\u000adeposition (CVD) is investigated. We observe in low mobility CVD graphene\\u000adevice a strong insulating behavior at low temperatures and a metallic behavior\\u000aat high temperatures manifesting a non-monotonic in the temperature dependent\\u000aresistivity.This feature is strongly affected by carrier density modulation. To\\u000aunderstand this anomalous temperature dependence, we introduce thermal\\u000aactivation

  13. Experimental Evidence for Ascorbate-Dependent Electron Transport in Leaves with Inactive Oxygen-Evolving Complexes1[OA

    PubMed Central

    Tóth, Szilvia Z.; Puthur, Jos T.; Nagy, Valéria; Garab, Gy?z?

    2009-01-01

    Previously, we showed that in barley (Hordeum vulgare) leaves with heat-inactivated oxygen-evolving complexes, photosystem II (PSII) has access to a large pool of alternative electron donors. Based on in vitro data, we proposed that this donor was ascorbate, yet this hypothesis has not been substantiated in vivo. In this paper, with the aid of chlorophyll a fluorescence induced by short (5-ms) light pulses and 820-nm absorbance transient measurements on wild-type and ascorbate-deficient (vtc2-1) mutant leaves of Arabidopsis (Arabidopsis thaliana), we show that in heat-treated leaves the rate of electron donation to PSII as well as the 3-(3,4-dichlorophenyl)-1,1-dimethylurea-sensitive electron transport toward photosystem I depend on the ascorbate content of the leaves: upon ascorbate treatment, the donation half-time in the wild type and the mutant decreased from 25 to 22 ms and from 55 to 32 ms, respectively. Thermoluminescence measurements show that TyrZ+ is involved in the electron transfer from ascorbate to PSII. These data and the similar ascorbate dependencies of the heat-treated and the tris(hydroxymethyl)aminomethane-treated thylakoid membranes, with maximal donation half-times of about 16 ms, show that ascorbate is capable of supporting a sustained electron transport activity in leaves containing inactivated oxygen-evolving complexes. This alternative electron transport appears to be ubiquitous in the plant kingdom and is present in the green alga Chlamydomonas reinhardtii, and its rate depends on the physiological state of the plants and on environmental conditions. Our data suggest that ascorbate, as an alternative PSII electron donor, plays a physiological role in heat-stressed plants. PMID:19144767

  14. Temperature dependence of electron transport in GaN/AlGaN quantum cascade detectors

    NASA Astrophysics Data System (ADS)

    Gryshchenko, S. V.; Klymenko, M. V.; Shulika, O. V.; Sukhoivanov, I. A.; Lysak, V. V.

    2012-10-01

    In this work we investigate the influence of extractor design and temperature on transport properties of quantum cascade detector. For this purpose we realize numerical calculation of electron lifetimes considering electron-phonon and electron impurities scattering. Electron-phonon interactions are treated using Fermi Golden Rule which allows to calculate lifetime of carriers with temperature and structure design taking into account. Transport characteristics of the quantum cascade detectors have been computed using density matrix theory. As a result, we have obtained the system of ordinary differential equations describing dynamics of electron distribution functions and intersubband correlations. Managing carrier lifetime in quantum wells gives us possibility to make device response faster. Also carrier lifetime is the relevant characteristic, allows us to calculate a lot of parameters such as quantum efficiency and photocurrent.

  15. Nonlinear random-walk approach to concentration-dependent contaminant transport in porous media

    Microsoft Academic Search

    Andrea Zoia; Christelle Latrille; Alain Cartalade

    2009-01-01

    We propose a nonlinear random-walk model to describe the dynamics of dense contaminant plumes in porous media. A coupling between concentration and velocity fields is found so that transport displays non-Fickian features. The qualitative behavior of the pollutant spatial profiles and moments is explored with the help of Monte Carlo simulation, within a continuous-time random-walk approach. Model outcomes are then

  16. Channel-Length-Dependent Transport Behaviors of Graphene Field-Effect Transistors

    Microsoft Academic Search

    Shu-Jen Han; Zhihong Chen; Ageeth A. Bol; Yanning Sun

    2011-01-01

    This letter presents a detailed study of transport in graphene field-effect transistors (GFETs) with various channel lengths, from 5 ?m down to 90 nm, using transferred graphene grown by chemical vapor deposition. An electron-hole asymmetry observed in short-channel devices suggests a strong impact from graphene\\/metal contacts. In addition, for the first time, we observe a shift of the gate voltage

  17. Temperature and illumination dependent junction transport in CdTe-CdS solar cells

    Microsoft Academic Search

    D. L. Linam; G. B. Lush; D. W. Dils; V. P. Singh; J. C. McClure

    2000-01-01

    Various electrical and optical techniques have been used to study junction transport mechanisms in CdTe-CdS solar cells. Current density versus voltage (J-V) characteristics were measured at various temperatures under various broad-spectrum illumination intensities, under visible wavelength monochromatic illumination, and under infrared (IR) illumination. The broad-spectrum J-V data was fit to a parallel diode model in order to extract diode parameters.

  18. Kinesin-Dependent Axonal Transport Is Mediated by the Sunday Driver (SYD) Protein

    Microsoft Academic Search

    Aaron B. Bowman; Adeela Kamal; Bruce W. Ritchings; Alastair Valentine Philp; Maura McGrail; Joseph G. Gindhart; Lawrence S. B. Goldstein

    2000-01-01

    A broadly conserved membrane-associated protein required for the functional interaction of kinesin-I with axonal cargo was identified. Mutations in sunday driver (syd) and the axonal transport motor kinesin-I cause similar phenotypes in Drosophila, including aberrant accumulations of axonal cargoes. GFP-tagged mammalian SYD localizes to tubulovesicular structures that costain for kinesin-I and a marker of the secretory pathway. Coimmunoprecipitation analysis indicates

  19. Enough is enough: TatA demand during Tat-dependent protein transport.

    PubMed

    Hauer, René Steffen; Schlesier, René; Heilmann, Kathleen; Dittmar, Julia; Jakob, Mario; Klösgen, Ralf Bernd

    2013-05-01

    The twin-arginine translocation (Tat(1)) pathway is unique with respect to its property to translocate proteins in a fully folded conformation across ion-tight membranes. In chloroplasts and Gram-negative bacteria, Tat translocase consists of the integral subunits TatB and TatC, which are assumed to constitute the membrane receptor, and TatA, a bitopic membrane protein being responsible in a yet unknown manner for the membrane translocation step. Antibody inhibition of intrinsic thylakoidal TatA activity and recovery of transport by heterologously expressed, purified TatA allowed to exactly quantify the amount of TatA required to catalyse membrane transport of the model Tat substrate 16/23. We can show that TatA concentrations in the 100nM range are sufficient to efficiently catalyse membrane transport of the protein, which corresponds well to the amount of TatA identified in thylakoids. Furthermore, TatA shows cooperativity in its catalytic activity suggesting that Tat translocase operates as an allosteric enzyme complex. PMID:23380705

  20. Nucleotide Dependent Packing Differences in Helical Crystals of the ABC Transporter MsbA

    PubMed Central

    Ward, Andrew; Mulligan, Sheila; Carragher, Bridget; Chang, Geoffrey; Milligan, Ronald A.

    2009-01-01

    Bacterial ATP binding cassette (ABC) exporters fulfill a wide variety of transmembrane transport roles and are homologous to the human multidrug resistance P-glycoprotein. Recent x-ray structures of the exporters MsbA and Sav1866 have begun to describe the conformational changes that accompany the ABC transport cycle. Here we present cryo-electron microscopy structures of MsbA reconstituted into a lipid bilayer. Using ATPase inhibitors, we captured three nucleotide transition states of the transporter that were subsequently reconstituted into helical arrays. The enzyme-substrate complex (trapped by ADP-aluminum fluoride or AMPPNP) crystallized in a different helical lattice than the enzyme-product complex (trapped by ADP-vanadate). ?20Å resolution maps were calculated for each state and revealed MsbA to be a dimer with a large channel between the membrane spanning domains, similar to the outward facing crystal structures of MsbA and Sav1866. This suggests that while there are likely structural differences between the nucleotide transition states, membrane embedded MsbA remains in an outward facing conformation while nucleotide is bound. PMID:19114108

  1. Cross talk of bumetanide-sensitive and HCO 3 ? -dependent transporters activated by IBMX in renal epithelial A6 cells

    Microsoft Academic Search

    N. Niisato; Y. Marunaka

    1997-01-01

    We studied cAMP-dependent regulation of ion transport in aldosterone-untreated renal epithelial A6 cells by measuring short-circuit\\u000a current (I\\u000a \\u000a sc\\u000a ). Biphasic increases in I\\u000a \\u000a sc\\u000a , a transient phase followed by a sustained one, were elicited in response to 1 mM 3-isobutyl-1-methylxanthine (IBMX, an inhibitor\\u000a of phosphodiesterase) which increased cytosolic cAMP concentration. IBMX increased the apical Cl? conductance. The sustained

  2. Extremely weak length-dependent spin transport along alkane chain in Fe3O4/monolayer molecules nanoparticles

    NASA Astrophysics Data System (ADS)

    Wu, Di; Wang, Shen; Yue, Fenjuan; Hu, An; Du, Youwei

    2010-03-01

    Spin transport along alkane chain is investigated using self-assembled monolayers (SAMs) saturated molecules on magnetic nanoparticles. Transmission electron microscopy shows the interparticle distance is about the length of the molecules. Temperature dependent resistivity exhibits variable range hopping behavior, which is attributed to the hopping in the nanoparticle. The resistivity exponentially increases with increasing the molecular length, indicating tunneling is dominant conduction mechanism in the saturated molecules. However, the magnetoresistance is almost constant even though resistivity changes two orders of magnitude at room temperature with varying the molecular length. At low temperature the magnetoresistance gradually increases due to the increase of the surface spin polarization of the nanoparticles.

  3. Magnetic Field-Dependent Interplay Between Incoherent and Fermi Liquid Transport Mechanisms in Low-Dimensional Tau Phase Organic Conductors

    NSDL National Science Digital Library

    Balicas, L.

    2000-01-01

    The US Department of Energy (DOE) Office of Scientific and Technical Information (OSTI) has recently posted a preprint in the field of condensed matter physics in its archive. The third, "Magnetic field-dependent interplay between incoherent and Fermi liquid transport mechanisms in low-dimensional tau phase organic conductors," contains recent experimental results from researchers at Florida State University's National High Magnetic Field Laboratory and the Theoretical and Physical Chemistry Research Institute of Greece. The URL takes readers to the abstract page, from which the full text can be downloaded in .dvi, .ps, or .pdf format.

  4. Color Entanglement for Azimuthal Asymmetries in the Drell-Yan Process

    NASA Astrophysics Data System (ADS)

    Buffing, M. G. A.; Mulders, P. J.

    2014-03-01

    In the resummation of collinear gluons emitted together with active partons from the hadrons in the Drell-Yan process, effects of color entanglement become important when the transverse directions are taken into account. It is then no longer possible to write the cross section as the convolution of two soft correlators and a hard part. We show that the color entanglement introduces additional color factors that must be taken into account in the extraction of transverse momentum-dependent parton distribution functions from azimuthal asymmetries. Examples where such effects matter are the extractions of the double Sivers and double Boer-Mulders asymmetries. Furthermore, we will argue why this color entanglement is a basic ingredient already in the tree-level description of azimuthal asymmetries.

  5. Color entanglement for azimuthal asymmetries in the Drell-Yan process.

    PubMed

    Buffing, M G A; Mulders, P J

    2014-03-01

    In the resummation of collinear gluons emitted together with active partons from the hadrons in the Drell-Yan process, effects of color entanglement become important when the transverse directions are taken into account. It is then no longer possible to write the cross section as the convolution of two soft correlators and a hard part. We show that the color entanglement introduces additional color factors that must be taken into account in the extraction of transverse momentum-dependent parton distribution functions from azimuthal asymmetries. Examples where such effects matter are the extractions of the double Sivers and double Boer-Mulders asymmetries. Furthermore, we will argue why this color entanglement is a basic ingredient already in the tree-level description of azimuthal asymmetries. PMID:24655247

  6. Parametric excitation of azimuthally non-symmetric surface waves propagating in metal waveguides filled with isotropic plasma

    NASA Astrophysics Data System (ADS)

    Girka, V. O.; Girka, ? O.; Sydora, R. D.; Ivahnenko, O.; Shkoda, Y.

    2015-06-01

    The paper is devoted to developing the theory of parametric excitation of electromagnetic waves propagating across the axis of symmetry in cylindrical waveguides partially filled with isotropic plasma. The problem is studied theoretically in the fluid approximation and expressions for the wave fields are derived from Maxwell’s equations. The azimuthally non-symmetric electromagnetic waves propagate in the form of wave packets which are approximately described by the main azimuthal harmonic and two nearest satellite temporal harmonics. The boundary condition, which is cast in a nonlinear form, describes the flowing of a surface current on the plasma interface. This condition allows one to derive an infinite set of equations for harmonics of the tangential electric field of azimuthally non-symmetric surface waves. The dependence of the growth rate of the parametric instability of these waves on parameters of the plasma-filled waveguide and alternating electric field is studied both analytically and numerically.

  7. Azimuthal anisotropy: Transition from hydrodynamic flow to jet suppression

    SciTech Connect

    Lacey, R.; PHENIX Collaboration, et al.

    2010-11-09

    Measured second and fourth azimuthal anisotropy coefficients v{sub 2,4}(N{sub part},p{sub T}) are scaled with the initial eccentricity {var_epsilon}{sub 2,4}(N{sub part}) of the collision zone and studied as a function of the number of participants N{sub part} and the transverse momenta p{sub T}. Scaling violations are observed for p{sub T} {le} 3 GeV/c, consistent with a p{sub T}{sup 2} dependence of viscous corrections and a linear increase of the relaxation time with p{sub T}. These empirical viscous corrections to flow and the thermal distribution function at freeze-out constrain estimates of the specific viscosity and the freeze-out temperature for two different models for the initial collision geometry. The apparent viscous corrections exhibit a sharp maximum for p{sub T} {ge} 3 GeV/c, suggesting a breakdown of the hydrodynamic ansatz and the onset of a change from flow-driven to suppression-driven anisotropy.

  8. Sodium-dependent multivitamin transporter gene is regulated at the chromatin level by histone biotinylation in human Jurkat lymphoblastoma cells.

    PubMed

    Zempleni, Janos; Gralla, Michael; Camporeale, Gabriela; Hassan, Yousef I

    2009-01-01

    The sodium-dependent multivitamin transporter (SMVT) is essential for mediating and regulating biotin entry into mammalian cells. In cells, holocarboxylase synthetase (HCS) mediates covalent binding of biotin to histones; biotinylation of lysine-12 in histone H4 (K12BioH4) causes gene repression. Here we propose a novel role for HCS in sensing and regulating levels of biotin in eukaryotic cells. We hypothesize that nuclear translocation of HCS increases in response to biotin supplementation; HCS then biotinylates histone H4 at SMVT promoters, silencing biotin transporter genes. We show that nuclear translocation of HCS is a biotin-dependent process that might involve tyrosine kinases, histone deacetylases, and histone methyltransferases in human lymphoid (Jurkat) cells. The nuclear translocation of HCS correlated with biotin concentrations in cell culture media; the relative enrichment of both HCS and K12BioH4 at SMVT promoter 1 (but not promoter 2) increased by 91% in cells cultured in medium containing 10 nmol/L biotin compared with 0.25 nmol/L biotin. This increase of K12BioH4 at the SMVT promoter was inversely linked to SMVT expression. Biotin homeostasis by HCS-dependent chromatin remodeling at the SMVT promoter 1 locus was disrupted in HCS knockdown cells, as evidenced by abnormal chromatin structure (K12BioH4 abundance) and increased SMVT expression. The findings from this study are consistent with the theory that HCS senses biotin, and that biotin regulates its own cellular uptake by participating in HCS-dependent chromatin remodeling events at the SMVT promoter 1 locus in Jurkat cells. PMID:19056636

  9. Linearized Hovering Control With One or More Azimuthing Thrusters

    E-print Network

    Hover, Franz S.

    2007-01-01

    We propose a simple method of control system design for marine vehicles with one or more azimuthing propulsors, and specifically for the case where the speed of the actuator is on the same time scale as the plant dynamic ...

  10. Doping-dependent thermopower of PbTe from Boltzmann transport calculations

    SciTech Connect

    Singh, David J. [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)

    2010-05-01

    The thermopower of PbTe as a function of temperature and doping level is reported based on Boltzmann transport calculations using the first principles relativistic electronic structure as obtained with the Engel-Vosko generalized gradient approximation. The results are discussed in relation to experimental data. For p-type material there is an enhancement at high-doping levels due to the onset of an increased density of states starting ~0.2 eV below the valence band edge. This leads to agreement between the calculated thermopower and recent results on PbTe with heavy Tl doping.

  11. Metal Domain Size Dependent Electrical Transport in Pt-CdSe Hybrid Nanoparticle Monolayers.

    PubMed

    Meyns, Michaela; Willing, Svenja; Lehmann, Hauke; Klinke, Christian

    2015-06-23

    Thin films prepared of semiconductor nanoparticles are promising for low-cost electronic applications such as transistors and solar cells. One hurdle for their breakthrough is their notoriously low conductivity. To address this, we precisely decorate CdSe nanoparticles with platinum domains of one to three nanometers in diameter by a facile and robust seeded growth method. We demonstrate the transition from semiconductor to metal dominated conduction in monolayered films. By adjusting the platinum content in such solution-processable hybrid, oligomeric nanoparticles the dark currents through deposited arrays become tunable while maintaining electronic confinement and photoconductivity. Comprehensive electrical measurements allow determining the reigning charge transport mechanisms. PMID:26052966

  12. Presynaptic Na+-dependent transport and exocytose of GABA and glutamate in brain in hypergravity.

    NASA Astrophysics Data System (ADS)

    Borisova, T.; Pozdnyakova, N.; Krisanova, N.; Himmelreich, N.

    ?-Aminobutyric acid (GABA) and L-glutamate are the most widespread neurotransmitter amino acids in the mammalian central nervous system. GABA is now widely recognized as the major inhibitory neurotransmitter. L-glutamate mediates the most of excitatory synaptic neurotransmission in the brain. They involved in the main aspects of normal brain function. The nerve terminals (synaptosomes) offer several advantages as a model system for the study of general mechanisms of neurosecretion. Our data allowed to conclude that exposure of animals to hypergravity (centrifugation of rats at 10G for 1 hour) had a profound effect on synaptic processes in brain. Comparative analysis of uptake and release of GABA and glutamate have demonstrated that hypergravity loading evokes oppositely directed alterations in inhibitory and excitatory signal transmission. We studied the maximal velocities of [^3H]GABA reuptake and revealed more than twofold enhancement of GABA transporter activity (Vmax rises from 1.4 |pm 0.3 nmol/min/mg of protein in the control group to 3.3 ± 0.59 nmol/min/mg of protein for animals exposed to hypergravity (P ? 0.05)). Recently we have also demonstrated the significant lowering of glutamate transporter activity (Vmax of glutamate reuptake decreased from 12.5 ± 3.2 nmol/min/mg of protein in the control group to 5.6 ± 0.9 nmol/min/mg of protein in the group of animals, exposed to the hypergravity stress (P ? 0.05)). Significant changes occurred in release of neurotransmitters induced by stimulating exocytosis with the agents, which depolarized nerve terminal plasma membrane. Depolarization-evoked Ca2+-stimulated release was more abundant for GABA (7.2 ± 0.54% and 11,74 ±1,2 % of total accumulated label for control and hypergravity, respectively (P?0.05)) and was essentially less for glutamate (14.4 ± 0.7% and 6.2 ± 1.9%) after exposure of animals to centrifuge induced artificial gravity. Changes observed in depolarization-evoked exocytotic release seem to be in a concert with alterations of plasma membrane transporters activity studied. Perhaps, lowering of glutamate transporter activity and increase of the velocity of GABA uptake correlated with diminution and augmentation of exocytotic release of these neurotransmitters, respectively. It is possible to suggest that observed changes in the activity of the processes responsible for the uptake and release of excitatory and inhibitory neurotransmitters are likely to be physiologically important and reflect making protective mechanisms more active for neutralization of harm influence of hypergravity stress.

  13. Cell kinetics of differentiation of Na/sup +/-dependent hexose transport in a cultured renal epithelial cell line

    SciTech Connect

    Cook, J.S.; Weiss, E.R.

    1985-01-01

    Fully differentiated cells of the renal proximal tubule have the capability of taking up hexoses across their apical borders by transport coupled to the Na/sup +/-electrochemical gradient. This property is also found in postconfluent cultures of the cloned cell line LLC-PK/sub 1/, a morphologically polarized line of renal cells. Postconfluent cells develop the Na/sup +/-dependent capacity to transport hexoses at their apical surface. This function is not observable during the growth phase of the cultures. To analyze the developmental process at the cellular level a method has been derived to separate transporting cells, expressing the differentiated function, from nontransporting cells. The method is based on the swelling of the cells accompanying the uptake of the nonmetabolizable glucose analog alpha methylglucoside. The swollen cells have a lower buoyant density than the undifferentiated cells and may be separated from them on density gradients. Analysis of the distribution of cells on such gradients shows that after the cells reach confluence the undifferentiated subpopulation is recruited onto the differentiation pathway with a rate constant of 0.2 per day, that 5 to 7 days are required for a cell to traverse this pathway to the fully differentiated state, and that once the maximum uptake capacity is achieved the cells do not develop further.

  14. Proteasome Failure Promotes Positioning of Lysosomes around the Aggresome via Local Block of Microtubule-Dependent Transport

    PubMed Central

    Zaarur, Nava; Meriin, Anatoli B.; Bejarano, Eloy; Xu, Xiaobin; Gabai, Vladimir L.; Cuervo, Ana Maria

    2014-01-01

    Ubiquitinated proteins aggregate upon proteasome failure, and the aggregates are transported to the aggresome. In aggresomes, protein aggregates are actively degraded by the autophagy-lysosome pathway, but why targeting the aggresome promotes degradation of aggregated species is currently unknown. Here we report that the important factor in this process is clustering of lysosomes around the aggresome via a novel mechanism. Proteasome inhibition causes formation of a zone around the centrosome where microtubular transport of lysosomes is suppressed, resulting in their entrapment and accumulation. Microtubule-dependent transport of other organelles, including autophagosomes, mitochondria, and endosomes, is also blocked in this entrapment zone (E-zone), while movement of organelles at the cell periphery remains unaffected. Following the whole-genome small interfering RNA (siRNA) screen for proteins involved in aggresome formation, we defined the pathway that regulates formation of the E-zone, including the Stk11 protein kinase, the Usp9x deubiquitinating enzyme, and their substrate kinase MARK4. Therefore, upon proteasome failure, targeting of aggregated proteins of the aggresome is coordinated with lysosome positioning around this body to facilitate degradation of the abnormal species. PMID:24469403

  15. Haemophilus parainfluenzae expresses diverse lipopolysaccharide O-antigens using ABC transporter and Wzy polymerase-dependent mechanisms

    PubMed Central

    Young, Rosanna E.B.; Twelkmeyer, Brigitte; Vitiazeva, Varvara; Power, Peter M.; Schweda, Elke K.H.; Hood, Derek W.

    2013-01-01

    Lipopolysaccharide O-antigens are the basis of serotyping schemes for Gram negative bacteria and help to determine the nature of host–bacterial interactions. Haemophilus parainfluenzae is a normal commensal of humans but is also an occasional pathogen. The prevalence, diversity and biosynthesis of O-antigens were investigated in this species for the first time. 18/18 commensal H. parainfluenzae isolates contain a O-antigen biosynthesis gene cluster flanked by glnA and pepB, the same position as the hmg locus for tetrasaccharide biosynthesis in Haemophilus influenzae. The O-antigen loci show diverse restriction digest patterns but fall into two main groups: (1) those encoding enzymes for the synthesis and transfer of FucNAc4N in addition to the Wzy-dependent mechanism of O-antigen synthesis and transport and (2) those encoding galactofuranose synthesis/transfer enzymes and an ABC transporter. The other glycosyltransferase genes differ between isolates. Three H. parainfluenzae isolates fell outside these groups and are predicted to synthesise O-antigens containing ribitol phosphate or deoxytalose. Isolates using the ABC transporter system encode a putative O-antigen ligase, required for the synthesis of O-antigen-containing LPS glycoforms, at a separate genomic location. The presence of an O-antigen contributes significantly to H. parainfluenzae resistance to the killing effect of human serum in vitro. The discovery of O-antigens in H. parainfluenzae is striking, as its close relative H. influenzae lacks this cell surface component. PMID:24035104

  16. Temperature dependence of spin-polarized transport in ferromagnet/unconventional superconductor junctions

    NASA Astrophysics Data System (ADS)

    Hirai, T.; Tanaka, Y.; Yoshida, N.; Asano, Y.; Inoue, J.; Kashiwaya, S.

    2003-05-01

    Tunneling conductance in ferromagnet/unconventional superconductor junctions is studied theoretically as a function of temperature and spin polarization in ferromagnets. In d-wave superconductor junctions, a zero-energy Andreev bound state drastically affects the temperature dependence of the zero-bias conductance (ZBC). In p-wave superconductor junctions, numerical results show various temperature dependences of the ZBC depending on the direction of the magnetic moment in ferromagnets and the pairing symmetry in superconductors such as px-, py-, and px+ipy-wave symmetries. The last one is a candidate for the pairing symmetry of Sr2RuO4. From these characteristic features in the conductance, we may obtain information about the degree of spin polarization in ferromagnets and the direction of the d vector in spin-triplet superconductors.

  17. Effects of symmetry and spin configuration on spin-dependent transport properties of iron-phthalocyanine-based devices

    NASA Astrophysics Data System (ADS)

    Cui, Li-Ling; Yang, Bing-Chu; Li, Xin-Mei; Cao, Can; Long, Meng-Qiu

    2014-07-01

    Spin-dependent transport properties of nanodevices constructed by iron-phthalocyanine (FePc) molecule sandwiched between two zigzag graphene nanoribbon electrodes are studied using first-principles quantum transport calculations. The effects of the symmetry and spin configuration of electrodes have been taken into account. It is found that large magnetoresistance, large spin polarization, dual spin-filtering, and negative differential resistance (NDR) can coexist in these devices. Our results show that 5Z-FePc system presents well conductive ability in both parallel (P) and anti-parallel (AP) configurations. For 6Z-FePc-P system, spin filtering effect and large spin polarization can be found. A dual spin filtering and NDR can also be shown in 6Z-FePc-AP. Our studies indicate that the dual spin filtering effect depends on the orbitals symmetry of the energy bands and spin mismatching of the electrodes. And all the effects would open up possibilities for their applications in spin-valve, spin-filter as well as effective spin diode devices.

  18. Pressure dependence of fluid transport properties of shallow fault systems in the Nankai subduction zone

    NASA Astrophysics Data System (ADS)

    Tanikawa, Wataru; Mukoyoshi, Hideki; Lin, Weiren; Hirose, Takehiro; Tsutsumi, Akito

    2014-12-01

    We measured fluid transport properties at an effective pressure of 40 MPa in core samples of sediments and fault rocks collected by the Integrated Ocean Drilling Program (IODP) NanTroSEIZE drilling project Expedition 316 from the megasplay fault system (site C0004) and the frontal thrust (site C0007) in the Nankai subduction zone. Permeability decreased with effective pressure as a power law function. Permeability values in the fault zones were 8 × 10-18 m2 at site C0004 and 9 × 10-18 m2 at site C0007. Stratigraphic variation in transport properties suggests that the megasplay fault zone may act as a barrier to fluid flow, but the frontal thrust fault zone might not. Depth variation in permeability at site C0007 is probably controlled by the mechanical compaction of sediment. Hydraulic diffusivity at shallow depths was approximately 1 × 10-6 m2 s-1 in both fault zones, which is small enough to lead to pore pressure generation that can cause dynamic fault weakening. However, absence of a very low permeable zone, which may have formed in the Japan Trench subduction zone, might prevent facilitation of huge shallow slips during Nankai subduction zone earthquakes. Porosity tests under dry conditions might have overestimated the porosity.

  19. Hyper-dependence of breast cancer cell types on the nuclear transporter Importin ?1.

    PubMed

    Kuusisto, Henna V; Jans, David A

    2015-08-01

    We previously reported that overexpression of members of the Importin (Imp) superfamily of nuclear transporters results in increased nuclear trafficking through conventional transport pathways in tumour cells. Here we show for the first time that the extent of overexpression of Imp?1 correlates with disease state in the MCF10 human breast tumour progression system. Excitingly, we find that targeting Imp?1 activity through siRNA is >30 times more efficient in decreasing the viability of malignant ductal carcinoma cells compared to isogenic non-transformed counterparts, and is highly potent and tumour selective at subnanomolar concentrations. Tumour cell selectivity of the siRNA effects was unique to Imp?1 and not other Imps, with flow cytometric analysis showing >60% increased cell death compared to controls concomitant with reduced nuclear import efficiency as indicated by confocal microscopic analysis. This hypersensitivity of malignant cell types to Imp?1 knockdown raises the exciting possibility of anti-cancer therapies targeted at Imp?1. PMID:25960398

  20. PIC modeling of material dependence on fast electron generation and transport

    NASA Astrophysics Data System (ADS)

    Mishra, R.; Wei, M. S.; Chawla, S.; Sentoku, Y.; Stephens, R. B.; Beg, F. N.

    2011-10-01

    2D collisional PIC simulations, using PICLS code that includes dynamic ionization and radiation cooling, are performed to model a recent experiment on the Titan laser using multi-foil targets, where 2x reduction in total fast electron flux and a smaller spot size through high-Z layer were observed. Modeling show that a thin high-Z transport layer (e.g., Au) near lower Z source layer introduces a collimating effect on fast electron transport. Strong self-generated resistive B-fields are produced inside Au layer and at the interface (Al/Au), which confine the fast electron propagation and can also trap electrons in wing region to inhibit their propagation. In addition, effects of the surface material on LPI produced fast electron source characteristics are examined in both planar and buried cone geometries. Supported by US DOE under contracts DE-AC52 07NA27344(ACE) and DE-FC02-04ER54789 (FSC).

  1. Cellular uptake of dietary flavonoid quercetin 4'-beta-glucoside by sodium-dependent glucose transporter SGLT1.

    PubMed

    Walgren, R A; Lin, J T; Kinne, R K; Walle, T

    2000-09-01

    Although it has been suggested that the intestinal glucose transporter may actively absorb dietary flavonoid glucosides, there is a lack of direct evidence for their transport by this system. In fact, our previous studies with the human Caco-2 cell model of intestinal absorption demonstrated that a major dietary flavonoid, quercetin 4'-beta-glucoside, is effluxed by apically expressed multidrug resistance-associated protein-2, potentially masking evidence for active absorption. The objective of this study was to test the hypothesis that quercetin 4'-beta-glucoside is a substrate for the intestinal sodium-dependent D-glucose cotransporter SGLT1. Cellular uptake of quercetin 4'-beta-glucoside was examined with Caco-2 cells and SGLT1 stably transfected Chinese hamster ovary cells (G6D3 cells). Although quercetin 4'-beta-glucoside is not absorbed across Caco-2 cell monolayers, examination of the cells by indirect fluorescent microscopy as well as by HPLC analysis of cellular content revealed cellular accumulation of this glucoside after apical loading. Consistent with previous observations, the accumulation of quercetin 4'-beta-glucoside in both Caco-2 and G6D3 cells was markedly enhanced in the presence of multidrug resistance-associated protein inhibition. Uptake of quercetin 4'-beta-glucoside was greater in SGLT1-transfected cells than in parental Chinese hamster ovary cells. Uptake of the glucoside by Caco-2 and G6D3 cells was sodium-dependent and was inhibited by the monovalent ionophore nystatin. In both Caco-2 and G6D3 cells, quercetin 4'-beta-glucoside uptake was inhibited by 30 mM glucose and 0.5 mM phloridzin. These results demonstrate for the first time that quercetin 4'-beta-glucoside is transported by SGLT1 across the apical membrane of enterocytes. PMID:10945831

  2. Simulation of channel orientation dependent transport in ultra-scaled monolayer MoX2 (X = S, Se, Te) n-MOSFETs

    NASA Astrophysics Data System (ADS)

    Chang, Jiwon

    2015-04-01

    Transport properties of about 3?nm channel length monolayer MoX2 (X = S, Se, Te) n-channel metal-oxide-semiconductor field effect transistors (MOSFETs) are examined through ballistic full-band quantum transport simulations with atomistic tight-binding Hamiltonians. Our simulations reveal that single gate (SG) monolayer MoX2 MOSFETs with an approximately 2?nm gate underlap exhibit reasonable subthreshold characteristics. From these full-band simulations, we observe channel orientation dependent negative differential resistance (NDR) in the out characteristics in the ballistic transport regime. We discuss and compare NDR properties of monolayer MoX2 n-channel MOSFETs in different transport directions.

  3. PHYSICAL REVIEW E 84, 041115 (2011) Heat generation and transport due to time-dependent forces

    E-print Network

    Li, Baowen

    2011-01-01

    's law [10,14,15] for diffusive systems. It is also expected that time-dependent external forces can of the main goals in nonequilibrium statistical physics. For systems driven arbitrarily far from equilibrium of heat current for the linear system. We found that the current can be expressed in terms

  4. Advances in colloid and biocolloid transport in porous media: particle size-dependent dispersivity and gravity effects

    NASA Astrophysics Data System (ADS)

    Chrysikopoulos, Constantinos V.; Manariotis, Ioannis D.; Syngouna, Vasiliki I.

    2014-05-01

    Accurate prediction of colloid and biocolloid transport in porous media relies heavily on usage of suitable dispersion coefficients. The widespread procedure for dispersion coefficient determination consists of conducting conservative tracer experiments and subsequently fitting the collected breakthrough data with a selected advection-dispersion transport model. The fitted dispersion coefficient is assumed to characterize the porous medium and is often used thereafter to analyze experimental results obtained from the same porous medium with other solutes, colloids, and biocolloids. The classical advection-dispersion equation implies that Fick's first law of diffusion adequately describes the dispersion process, or that the dispersive flux is proportional to the concentration gradient. Therefore, the above-described procedure inherently assumes that the dispersive flux of all solutes, colloids and biocolloids under the same flow field conditions is exactly the same. Furthermore, the available mathematical models for colloid and biocoloid transport in porous media do not adequately account for gravity effects. Here an extensive laboratory study was undertaken in order to assess whether the dispersivity, which traditionally has been considered to be a property of the porous medium, is dependent on colloid particle size, interstitial velocity and length scale. The breakthrough curves were successfully simulated with a mathematical model describing colloid and biocolloid transport in homogeneous, water saturated porous media. The results demonstrated that the dispersivity increases very slowly with increasing interstitial velocity, and increases with column length. Furthermore, contrary to earlier results, which were based either on just a few experimental observations or experimental conditions leading to low mass recoveries, dispersivity was positively correlated with colloid particle size. Also, transport experiments were performed with biocolloids (bacteriophages: ?X174, MS2) and colloids (clays: kaolinite KGa-1b, montmorillonite STx-1b) in packed columns placed in various orientations (horizontal, vertical, and diagonal) under both up-flow and down-flow modes. All experiments were conducted under electrostatically unfavorable conditions. The experimental data were fitted with a newly developed, analytical, one dimensional, colloid and biocolloid transport model, accounting for gravity effects. The results revealed that flow direction has a significant influence on particle deposition. The rate of particle deposition was shown to be greater for up-flow than for down-flow direction, suggesting that gravity was a significant driving force for biocolloid and colloid deposition.

  5. Decoherent time-dependent transport beyond the Landauer-Büttiker formulation: a quantum-drift alternative to quantum jumps

    E-print Network

    Lucas J. Fernández-Alcázar; Horacio M. Pastawski

    2015-02-27

    We present a model for decoherence in time-dependent transport. It boils down into a form of wave function that undergoes a smooth stochastic drift of the phase in a local basis, the Quantum Drift (QD) model. This drift is nothing else but a local energy fluctuation. Unlike Quantum Jumps (QJ) models, no jumps are present in the density as the evolution is unitary. As a first application, we address the transport through a resonant state $\\left\\vert 0\\right\\rangle $ that undergoes decoherence. We show the equivalence with the decoherent steady state transport in presence of a B\\"{u}ttiker's voltage probe. In order to test the dynamics, we consider two many-spin systems whith a local energy fluctuation. A two-spin system is reduced to a two level system (TLS) that oscillates among $\\left\\vert 0\\right\\rangle $ $\\equiv $ $ \\left\\vert \\uparrow \\downarrow \\right\\rangle $ and $\\left\\vert 1\\right\\rangle \\equiv $ $\\left\\vert \\downarrow \\uparrow \\right\\rangle $. We show that QD model recovers not only the exponential damping of the oscillations in the low perturbation regime, but also the non-trivial bifurcation of the damping rates at a critical point, i.e. the quantum dynamical phase transition. We also address the spin-wave like dynamics of local polarization in a spin chain. The QD average solution has about half the dispersion respect to the mean dynamics than QJ. By evaluating the Loschmidt Echo (LE), we find that the pure states $\\left\\vert 0\\right\\rangle $ and $\\left\\vert 1\\right \\rangle $ are quite robust against the local decoherence. In contrast, the LE, and hence coherence, decays faster when the system is in a superposition state. Because its simple implementation, the method is well suited to assess decoherent transport problems as well as to include decoherence in both one-body and many-body dynamics.

  6. Long-range azimuthal correlations in proton-proton and proton-nucleus collisions from the incoherent scattering of partons

    DOE PAGESBeta

    Ma, Guo -Liang [Chinese Academy of Sciences, Shanghai (China). Shanghai Institute of Applied Physics; Bzdak, Adam [Brookhaven National Laboratory (BNL), Upton, NY (United States). Riken BNL Research Center

    2014-12-01

    We show that the incoherent elastic scattering of partons, as present in a multi-phase transport model (AMPT), with a modest parton–parton cross-section of ?=1.5–3 mb?=1.5–3 mb, naturally explains the long-range two-particle azimuthal correlation as observed in proton–proton and proton–nucleus collisions at the Large Hadron Collider.

  7. Akt-dependent and isoform-specific regulation of dopamine transporter cell surface expression.

    PubMed

    Speed, Nicole K; Matthies, Heinrich J G; Kennedy, J Phillip; Vaughan, Roxanne A; Javitch, Jonathan A; Russo, Scott J; Lindsley, Craig W; Niswender, Kevin; Galli, Aurelio

    2010-07-21

    Dopamine (DA) is a neurotransmitter implicated in multiple functions, including movement, cognition, motivation, and reward. The DA transporter (DAT) is responsible for clearing extracellular DA, thereby terminating DA neurotransmission. Previously, it has been shown that insulin signaling through protein kinase B/Akt regulates DAT function by fine-tuning DAT cell surface expression. Importantly, specific Akt isoforms (e.g., Akt1, Akt2) serve distinct physiological functions. Here, we demonstrate using isoform-specific Akt inhibitors that basal activity of Akt2, rather than Akt1, regulates DAT cell surface expression. Since Akt2 activation is mediated by insulin, these data further implicate insulin signaling as an important modulator of DAT function and dopaminergic tone. PMID:22778840

  8. Resistive Switching and Temperature-dependent Transport in HfOx-based Resistive Memory Devices

    NASA Astrophysics Data System (ADS)

    Kim, Seyoung; Ahn, Chiyui; Gokmen, Tayfun; Dial, Oliver; Ritter, Mark

    2014-03-01

    Resistive switching phenomenon in transition metal oxide materials has been studied intensively as a candidate technology for future non-volatile memory applications and electronic synapse devices. Here, we demonstrate an HfOx-based resistive memory device with rare earth metal contact in which the device resistance can be modulated with applied voltage and current. Repeatable and self-compliance switching as well as high yield and device-to-device uniformity are achieved in our devices. To understand the conduction mechanism, we perform transport measurement in multiple devices at different resistance states (initial, low and high resistance states) by probing current as a function of applied voltage at temperatures from 40K to 350K. We find that temperature insensitive tunneling conduction dominates at low temperature, while thermally activated conduction is observed at high temperature. Trap-assisted tunneling and Poole-Frenkel mechanisms are accounted for the characteristics found in different regimes.

  9. Lysine 27 ubiquitination of the mitochondrial transport protein Miro is dependent on serine 65 of the Parkin ubiquitin ligase.

    PubMed

    Birsa, Nicol; Norkett, Rosalind; Wauer, Tobias; Mevissen, Tycho E T; Wu, Hsiu-Chuan; Foltynie, Thomas; Bhatia, Kailash; Hirst, Warren D; Komander, David; Plun-Favreau, Helene; Kittler, Josef T

    2014-05-23

    Mitochondrial transport plays an important role in matching mitochondrial distribution to localized energy production and calcium buffering requirements. Here, we demonstrate that Miro1, an outer mitochondrial membrane (OMM) protein crucial for the regulation of mitochondrial trafficking and distribution, is a substrate of the PINK1/Parkin mitochondrial quality control system in human dopaminergic neuroblastoma cells. Moreover, Miro1 turnover on damaged mitochondria is altered in Parkinson disease (PD) patient-derived fibroblasts containing a pathogenic mutation in the PARK2 gene (encoding Parkin). By analyzing the kinetics of Miro1 ubiquitination, we further demonstrate that mitochondrial damage triggers rapid (within minutes) and persistent Lys-27-type ubiquitination of Miro1 on the OMM, dependent on PINK1 and Parkin. Proteasomal degradation of Miro1 is then seen on a slower time scale, within 2-3 h of the onset of ubiquitination. We find Miro ubiquitination in dopaminergic neuroblastoma cells is independent of Miro1 phosphorylation at Ser-156 but is dependent on the recently identified Ser-65 residue within Parkin that is phosphorylated by PINK1. Interestingly, we find that Miro1 can stabilize phospho-mutant versions of Parkin on the OMM, suggesting that Miro is also part of a Parkin receptor complex. Moreover, we demonstrate that Ser-65 in Parkin is critical for regulating Miro levels upon mitochondrial damage in rodent cortical neurons. Our results provide new insights into the ubiquitination-dependent regulation of the Miro-mediated mitochondrial transport machinery by PINK1/Parkin and also suggest that disruption of this regulation may be implicated in Parkinson disease pathogenesis. PMID:24671417

  10. Lysine 27 Ubiquitination of the Mitochondrial Transport Protein Miro Is Dependent on Serine 65 of the Parkin Ubiquitin Ligase*

    PubMed Central

    Birsa, Nicol; Norkett, Rosalind; Wauer, Tobias; Mevissen, Tycho E. T.; Wu, Hsiu-Chuan; Foltynie, Thomas; Bhatia, Kailash; Hirst, Warren D.; Komander, David; Plun-Favreau, Helene; Kittler, Josef T.

    2014-01-01

    Mitochondrial transport plays an important role in matching mitochondrial distribution to localized energy production and calcium buffering requirements. Here, we demonstrate that Miro1, an outer mitochondrial membrane (OMM) protein crucial for the regulation of mitochondrial trafficking and distribution, is a substrate of the PINK1/Parkin mitochondrial quality control system in human dopaminergic neuroblastoma cells. Moreover, Miro1 turnover on damaged mitochondria is altered in Parkinson disease (PD) patient-derived fibroblasts containing a pathogenic mutation in the PARK2 gene (encoding Parkin). By analyzing the kinetics of Miro1 ubiquitination, we further demonstrate that mitochondrial damage triggers rapid (within minutes) and persistent Lys-27-type ubiquitination of Miro1 on the OMM, dependent on PINK1 and Parkin. Proteasomal degradation of Miro1 is then seen on a slower time scale, within 2–3 h of the onset of ubiquitination. We find Miro ubiquitination in dopaminergic neuroblastoma cells is independent of Miro1 phosphorylation at Ser-156 but is dependent on the recently identified Ser-65 residue within Parkin that is phosphorylated by PINK1. Interestingly, we find that Miro1 can stabilize phospho-mutant versions of Parkin on the OMM, suggesting that Miro is also part of a Parkin receptor complex. Moreover, we demonstrate that Ser-65 in Parkin is critical for regulating Miro levels upon mitochondrial damage in rodent cortical neurons. Our results provide new insights into the ubiquitination-dependent regulation of the Miro-mediated mitochondrial transport machinery by PINK1/Parkin and also suggest that disruption of this regulation may be implicated in Parkinson disease pathogenesis. PMID:24671417

  11. Cooperative effect of pH-dependent ion transport within two symmetric-structured nanochannels.

    PubMed

    Meng, Zheyi; Chen, Yang; Li, Xiulin; Xu, Yanglei; Zhai, Jin

    2015-04-15

    A novel and simple design is introduced to construct bichannel nanofluid diodes by combining two poly(ethylene terephthalate) (PET) films with columnar nanochannel arrays varying in size or in surface charge. This type of bichannel device performs obvious ion current rectification, and the pH-dependent tunability and degree of rectification can be improved by histidine modification. The origin of the ion current rectification and its pH-dependent tunability are attributed to the cooperative effect of the two columnar half-channels and the applied bias on the mobile ions. As a result of surface groups on the bichannel being charged with different polarities or degrees at different pH values, the function of the bichannel device can be converted from a nanofluid diode to a normal nanochannel or to a reverse diode. PMID:25806828

  12. Na-dependent L-proline transport by eel intestinal brush-border membrane vesicles

    SciTech Connect

    Vilella, S.; Ahearn, G.A.; Cassano, G.; Storelli, C. (Universita' di Lecce (Italy) University of Hawaii at Manoa, Honolulu (USA))

    1988-10-01

    L-({sup 3}H)proline uptake by brush-border membrane vesicles prepared from intestinal mucosa of the European eel, Anguilla anguilla, was stimulated by a transmembrane Na gradient (out > in.) Kinetic analysis of L-proline influx, under short-circuited membrane potential conditions, indicated the presence of an apparent single Na-dependent carrier process and a nonsaturable transfer component with an apparent diffusional permeability (P) of 1.53 {plus minus} 0.35 {mu}l{center dot}mg protein{sup {minus}1}{center dot}min{sup {minus}1}. An imposed transmembrane potential (inside negative) increased apparent L-proline binding affinity (lowered K{sub app}) without appreciably altering maximal amino acid influx (J{sub max}). Hill analysis of L-proline influx over a wide range of external Na concentrations indicated a 1:1 stoichiometry for Na-proline cotransport. Use of amino acid inhibitors of L-proline influx suggested that L-proline transfer may occur by either a classical Na-dependent A System with a wide substrate specificity or by the combination of Na-dependent PHE (phenylalanine preferring) and IMINO (proline, {alpha}-methylaminoisobutyric acid preferring) Systems.

  13. A rate code for sound azimuth in monkey auditory cortex: implications for human neuroimaging studies

    PubMed Central

    Werner-Reiss, Uri; Groh, Jennifer M.

    2013-01-01

    Is sound location represented in the auditory cortex of humans and monkeys? Human neuroimaging experiments have had only mixed success at demonstrating sound location sensitivity in primary auditory cortex. This is in apparent conflict with studies in monkeys and other animals, where single-unit recording studies have found stronger evidence for spatial sensitivity. Does this apparent discrepancy reflect a difference between humans and animals, or does it reflect differences in the sensitivity of the methods used for assessing the representation of sound location? The sensitivity of imaging methods such as fMRI depends on two key aspects of the underlying neuronal population: (1) what kind of spatial sensitivity individual neurons exhibit, and (2) whether neurons with similar response preferences are clustered within the brain. To address this question, we conducted a single unit recording study in monkeys. We investigated the nature of spatial sensitivity in individual auditory cortical neurons to determine whether they have receptive fields (place code) or monotonic (rate code) sensitivity to sound azimuth. Secondly, we tested how strongly the population of neurons favors contralateral locations. We report here that the majority of neurons show predominantly monotonic azimuthal sensitivity, forming a rate code for sound azimuth, but that at the population level the degree of contralaterality is modest. This suggests that the weakness of the evidence for spatial sensitivity in human neuroimaging studies of auditory cortex may be due to limited lateralization at the population level, despite what may be considerable spatial sensitivity in individual neurons. PMID:18385333

  14. Azimuthal asymmetries of charged hadrons produced muons off longitudinally polarised deuterons at COMPASS

    NASA Astrophysics Data System (ADS)

    Efremov, Anatoly; COMPASS Collaboration

    2011-05-01

    Azimuthal asymmetries in semi-inclusive production of positive (h+) and negative hadrons (h-) have been measured by scattering of 160 GeV muons off longitudinally polarised deuterons at CERN. The asymmetries were decomposed in several terms, according to their expected modulation as a function of the outgoing hadron azimuthal angle phi. Each term receives contributions from one or several spin and transverse-momentum-dependent parton distribution and fragmentation functions. The amplitudes of all phi-modulation terms of the hadron asymmetries integrated over the kinematic variables are found to be consistent with zero within statistical errors, while the constant terms are nonzero and equal for h+ and h-within the statistical errors. The dependencies of the phi-modulated terms versus the Bjorken momentum fraction x, the hadron fractional momentum z, and the hadron transverse momentum pTh were studied. The x dependence of the constant terms for both positive and negative hadrons is in agreement with the longitudinal double-spin hadron asymmetries, measured in semi-inclusive deep-inelastic scattering. The x dependence of the sin phi-modulation term is less pronounced than that in the corresponding HERMES data. All other dependencies of the phi-modulation amplitudes are consistent with zero within the statistical errors.

  15. Azimuthal asymmetries of charged hadrons produced by high-energy muons scattered off longitudinally polarised deuterons

    NASA Astrophysics Data System (ADS)

    Alekseev, M. G.; Alexakhin, V. Yu.; Alexandrov, Yu.; Alexeev, G. D.; Amoroso, A.; Austregesilo, A.; Bade?ek, B.; Balestra, F.; Barth, J.; Baum, G.; Bedfer, Y.; Bernhard, J.; Bertini, R.; Bettinelli, M.; Birsa, R.; Bisplinghoff, J.; Bordalo, P.; Bradamante, F.; Bravar, A.; Bressan, A.; Brona, G.; Burtin, E.; Bussa, M. P.; Chaberny, D.; Chiosso, M.; Chung, S. U.; Cicuttin, A.; Colantoni, M.; Crespo, M. L.; Dalla Torre, S.; Das, S.; Dasgupta, S. S.; Denisov, O. Yu.; Dhara, L.; Diaz, V.; Donskov, S. V.; Doshita, N.; Duic, V.; Dünnweber, W.; Efremov, A.; El Alaoui, A.; Eversheim, P. D.; Eyrich, W.; Faessler, M.; Ferrero, A.; Filin, A.; Finger, M.; Finger, M.; Fischer, H.; Franco, C.; Friedrich, J. M.; Garfagnini, R.; Gautheron, F.; Gavrichtchouk, O. P.; Gazda, R.; Gerassimov, S.; Geyer, R.; Giorgi, M.; Gnesi, I.; Gobbo, B.; Goertz, S.; Grabmüller, S.; Grasso, A.; Grube, B.; Gushterski, R.; Guskov, A.; Haas, F.; von Harrach, D.; Hasegawa, T.; Heinsius, F. H.; Herrmann, F.; Heß, C.; Hinterberger, F.; Horikawa, N.; Höppner, Ch.; D'Hose, N.; Ilgner, C.; Ishimoto, S.; Ivanov, O.; Ivanshin, Yu.; Iwata, T.; Jahn, R.; Jasinski, P.; Jegou, G.; Joosten, R.; Kabuß, E.; Kang, D.; Ketzer, B.; Khaustov, G. V.; Khokhlov, Yu. A.; Kisselev, Yu.; Klein, F.; Klimaszewski, K.; Koblitz, S.; Koivuniemi, J. H.; Kolosov, V. N.; Kondo, K.; Königsmann, K.; Konopka, R.; Konorov, I.; Konstantinov, V. F.; Korzenev, A.; Kotzinian, A. M.; Kouznetsov, O.; Kowalik, K.; Krämer, M.; Kral, A.; Kroumchtein, Z. V.; Kuhn, R.; Kunne, F.; Kurek, K.; Lauser, L.; Le Goff, J. M.; Lednev, A. A.; Lehmann, A.; Levorato, S.; Lichtenstadt, J.; Liska, T.; Maggiora, A.; Maggiora, M.; Magnon, A.; Mallot, G. K.; Mann, A.; Marchand, C.; Martin, A.; Marzec, J.; Massmann, F.; Matsuda, T.; Meyer, W.; Michigami, T.; Mikhailov, Yu. V.; Moinester, M. A.; Mutter, A.; Nagaytsev, A.; Nagel, T.; Nassalski, J.; Negrini, T.; Nerling, F.; Neubert, S.; Neyret, D.; Nikolaenko, V. I.; Nunes, A. S.; Olshevsky, A. G.; Ostrick, M.; Padee, A.; Panknin, R.; Panzieri, D.; Parsamyan, B.; Paul, S.; Pawlukiewicz-Kaminska, B.; Perevalova, E.; Pesaro, G.; Peshekhonov, D. V.; Piragino, G.; Platchkov, S.; Pochodzalla, J.; Polak, J.; Polyakov, V. A.; Pontecorvo, G.; Pretz, J.; Quintans, C.; Rajotte, J.-F.; Ramos, S.; Rapatsky, V.; Reicherz, G.; Richter, A.; Robinet, F.; Rocco, E.; Rondio, E.; Ryabchikov, D. I.; Samoylenko, V. D.; Sandacz, A.; Santos, H.; Sapozhnikov, M. G.; Sarkar, S.; Savin, I. A.; Sbrizzai, G.; Schiavon, P.; Schill, C.; Schlüter, T.; Schmitt, L.; Schopferer, S.; Schröder, W.; Shevchenko, O. Yu.; Siebert, H.-W.; Silva, L.; Sinha, L.; Sissakian, A. N.; Slunecka, M.; Smirnov, G. I.; Sosio, S.; Sozzi, F.; Srnka, A.; Stolarski, M.; Sulc, M.; Sulej, R.; Takekawa, S.; Tessaro, S.; Tessarotto, F.; Teufel, A.; Tkatchev, L. G.; Uhl, S.; Uman, I.; Virius, M.; Vlassov, N. V.; Vossen, A.; Weitzel, Q.; Windmolders, R.; Wi?licki, W.; Wollny, H.; Zaremba, K.; Zavertyaev, M.; Zemlyanichkina, E.; Ziembicki, M.; Zhao, J.; Zhuravlev, N.; Zvyagin, A.

    2010-11-01

    Azimuthal asymmetries in semi-inclusive production of positive ( h +) and negative hadrons ( h -) have been measured by scattering 160 GeV muons off longitudinally polarised deuterons at CERN. The asymmetries were decomposed in several terms according to their expected modulation in the azimuthal angle ? of the outgoing hadron. Each term receives contributions from one or several spin and transverse-momentum-dependent parton distribution and fragmentation functions. The amplitudes of all ?-modulation terms of the hadron asymmetries integrated over the kinematic variables are found to be consistent with zero within statistical errors, while the constant terms are nonzero and equal for h + and h - within the statistical errors. The dependencies of the ?-modulated terms versus the Bjorken momentum fraction x, the hadron fractional momentum z, and the hadron transverse momentum phT were studied. The x dependence of the constant terms for both positive and negative hadrons is in agreement with the longitudinal double-spin hadron asymmetries, measured in semi-inclusive deep-inelastic scattering. The x dependence of the sin ?-modulation term is less pronounced than that in the corresponding HERMES data. All other dependencies of the ?-modulation amplitudes are consistent with zero within the statistical errors.

  16. Azimuthal asymmetries of charged hadrons produced by high-energy muons scattered off longitudinally polarised deuterons

    E-print Network

    COMPASS Collaboration

    2010-09-18

    Azimuthal asymmetries in semi-inclusive production of positive (h^+) and negative hadrons (h^-) have been measured by scattering 160 GeV muons off longitudinally polarised deuterons at CERN. The asymmetries were decomposed in several terms according to their expected modulation in the azimuthal angle phi of the outgoing hadron. Each term receives contributions from one or several spin and transverse-momentum-dependent parton distribution and fragmentation functions. The amplitudes of all phi-modulation terms of the hadron asymmetries integrated over the kinematic variables are found to be consistent with zero within statistical errors, while the constant terms are nonzero and equal for h^+ and h^- within the statistical errors. The dependencies of the phi-modulated terms versus the Bjorken momentum fraction x, the hadron fractional momentum z, and the hadron transverse momentum p_h^T were studied. The x dependence of the constant terms for both positive and negative hadrons is in agreement with the longitudinal double-spin hadron asymmetries, measured in semi-inclusive deep-inelastic scattering. The x dependence of the sin phi-modulation term is less pronounced than that in the corresponding HERMES data. All other dependencies of the phi-modulation amplitudes are consistent with zero within the statistical errors.

  17. Inhibition by pertussis toxin of the activation of Na(+)-dependent uridine transport in dimethyl-sulphoxide-induced HL-60 leukaemia cells.

    PubMed Central

    Sokoloski, J A; Sartorelli, A C; Handschumacher, R E; Lee, C W

    1991-01-01

    The effects of pertussis toxin on the Na(+)-dependent transport of uridine were studied in HL-60 leukaemia cells induced to differentiate along the granulocytic or monocytic pathways by dimethyl sulphoxide (DMSO) or phorbol 12-myristate 13-acetate (PMA) respectively. Pertussis toxin at 50 ng/ml completely inhibited the activation of Na(+)-dependent uridine transport and consequently prevented the formation of intracellular pools of free uridine which occurs in HL-60 cells induced to differentiate by DMSO. The inhibition of Na(+)-dependent uridine transport by pertussis toxin in cells exposed to DMSO was associated with a 14-fold decrease in affinity, with no change in Vmax. Pertussis toxin, however, had no effect on Na(+)-dependent uridine transport in PMA-induced HL-60 cells. Furthermore, 500 ng of cholera toxin/ml had no effect on the Na(+)-dependent uptake of uridine in DMSO-treated HL-60 cells. These results suggest that the activation of the Na(+)-dependent transport of uridine in HL-60 cells induced to differentiate along the granulocytic pathway by DMSO is coupled to a pertussis-toxin-sensitive guanine-nucleotide binding protein (G-protein). PMID:1747127

  18. Na+ dependent acid-base transporters in the choroid plexus; insights from slc4 and slc9 gene deletion studies

    PubMed Central

    Christensen, Henriette L.; Nguyen, An T.; Pedersen, Fredrik D.; Damkier, Helle H.

    2013-01-01

    The choroid plexus epithelium (CPE) is located in the ventricular system of the brain, where it secretes the majority of the cerebrospinal fluid (CSF) that fills the ventricular system and surrounds the central nervous system. The CPE is a highly vascularized single layer of cuboidal cells with an unsurpassed transepithelial water and solute transport rate. Several members of the slc4a family of bicarbonate transporters are expressed in the CPE. In the basolateral membrane the electroneutral Na+ dependent Cl?/HCO3? exchanger, NCBE (slc4a10) is expressed. In the luminal membrane, the electrogenic Na+:HCO3? cotransporter, NBCe2 (slc4a5) is expressed. The electroneutral Na+:HCO3? cotransporter, NBCn1 (slc4a7), has been located in both membranes. In addition to the bicarbonate transporters, the Na+/H+ exchanger, NHE1 (slc9a1), is located in the luminal membrane of the CPE. Genetically modified mice targeting slc4a2, slc4a5, slc4a7, slc4a10, and slc9a1 have been generated. Deletion of slc4a5, 7 or 10, or slc9a1 has numerous impacts on CP function and structure in these mice. Removal of the transporters affects brain ventricle size (slc4a5 and slc4a10) and intracellular pH regulation (slc4a7 and slc4a10). In some instances, removal of the proteins from the CPE (slc4a5, 7, and 10) causes changes in abundance and localization of non-target transporters known to be involved in pH regulation and CSF secretion. The focus of this review is to combine the insights gathered from these knockout mice to highlight the impact of slc4 gene deletion on the CSF production and intracellular pH regulation resulting from the deletion of slc4a5, 7 and 10, and slc9a1. Furthermore, the review contains a comparison of the described human mutations of these genes to the findings in the knockout studies. Finally, the future perspective of utilizing these proteins as potential targets for the treatment of CSF disorders will be discussed. PMID:24155723

  19. Scale-Dependent Fracture-Matrix Interactions and Their Impact on Radionuclide Transport: Development of efficient particle-tracking methods

    SciTech Connect

    Rajaram, Harihar [University of Colorado, Boulder; Brutz, Michael [University of Colorado, Boulder; Klein, Dylan R [University of Colorado, Boulder; Mallikamas, Wasin [University of Colorado, Boulder

    2014-09-18

    Matrix Diffusion and Adsorption within a rock matrix are important mechanisms for retarding transport of radionuclides in fractured rock. Due to computational limitations and difficulties in characterizing complex subsurface systems, diffusive exchange between a fracture network and surrounding rock matrix is often modeled using simplified conceptual representations. There is significant uncertainty in “effective” parameters used in these models, such as the “effective matrix diffusivity”. Often, these parameters are estimated by fitting sparse breakthrough data, and estimated values fall outside meaningful ranges, because simplified interpretive models do not consider complex three-dimensional flow. There is limited understanding of the relationship between the effective parameters and rock mass characteristics including network structure and matrix properties. There is also evidence for an apparent scale-dependence in “effective matrix diffusion” coefficients. These observations raise questions on whether fracture-matrix interaction parameters estimated from small-scale tracer tests can be used for predicting radionuclide fate and transport at the scale of DOE field sites. High-resolution three-dimensional Discrete-Fracture-Network-Matrix (DFNM) models based on well-defined local scale transport equations can help to address some of these questions. Due to tremendous advances in computational technology over the last 10 years, DFNM modeling in relatively large domains is now feasible. The overarching objective of our research is to use DFNM modeling to improve fundamental understanding of how effective parameters in conceptual models are related to fracture network structure and matrix properties. An advanced three-dimensional DFNM model is being developed, which combines upscaled particle-tracking algorithms for fracture-matrix interaction and a parallel fracture-network flow simulator. The particle-tracking algorithms allow complexity in flow fields at different scales, and track transport across fracture-matrix interfaces based on rigorous local approximations to the transport equations. This modeling approach can incorporate aperture variability, multi-scale preferential flow and matrix heterogeneity. We developed efficient particle-tracking methods for handling matrix diffusion and adsorption on fracture walls and demonstrated their efficiency for use within the context of large-scale complex fracture network models with variability in apertures across a network of fractures and within individual fractures.

  20. Semiclassical theory of the Ehrenfest time dependence of quantum transport in ballistic quantum dots

    NASA Astrophysics Data System (ADS)

    Brouwer, Piet W.; Rahav, Saar

    2006-08-01

    We present a trajectory-based semiclassical calculation of the Ehrenfest-time dependence of the weak localization correction and the universal conductance fluctuations of a ballistic quantum dot with ideal point contacts. While the weak localization correction is proportional to exp(-?E/?D) , where ?E and ?D are the dot’s Ehrenfest time and dwell time, respectively, the variance of the conductance is found to be independent of ?E . The latter is in agreement with numerical simulations of the quantum kicked rotator [J. Tworzydlo , Phys. Rev. B 69, 165318 (2004) and P. Jacquod and E. V. Sukhorukov, Phys. Rev. Lett. 92, 116801 (2004)].

  1. Temperature-dependence of ink transport during thermal dip-pen nanolithography

    NASA Astrophysics Data System (ADS)

    Chung, Sungwook; Felts, Jonathan R.; Wang, Debin; King, William P.; De Yoreo, James J.

    2011-11-01

    We investigate the control of tip temperature on feature size during dip-pen nanolithography (DPN) of mercaptohexadecanoic acid (MHA) on Au. Heated atomic force microscopy (AFM) probes operated between 25 °C and 50 °C wrote nanostructures of MHA for various dwell times and tip speeds. The feature size exhibited an exponential dependence on tip temperature with an apparent activation barrier of 165 kJ/mol. Analysis of the ink transfer process shows that, while ˜1/3 of the barrier is from ink dissolution into the meniscus, the rest reflects the barrier to adsorption onto the growing feature, a process that has been ignored in previous DPN models.

  2. Temperature-dependent Transport Properties of CVD grown Graphene with Pd Functionalization

    NASA Astrophysics Data System (ADS)

    Zhong, Bochen; Uddin, Ahsan; Singh, Amol; Koley, Goutam; Webb, Richard

    2015-03-01

    We have investigated the temperature dependence of carrier density and mobility of CVD grown graphene before and after 2nm Pd deposition by Hall effect measurement. In our samples, Hall mobility increases as temperature increases, indicating that Coulomb scattering is the most important scattering mechanism. The Pd functionalization layer scattering limited carrier mobility is calculated as a function of temperature, and a least-square fit is done. Furthermore, Hall mobility of the Pd-functionalized graphene enhances significantly after exposure to H2 and the dominant scattering mechanism switches to thermal excited substrate optical phonon scattering.

  3. Temperature-Dependent Water and Ion Transport Properties of Barley and Sorghum Roots 1

    PubMed Central

    BassiriRad, Hormoz; Radin, John W.; Matsuda, Kaoru

    1991-01-01

    Root temperature strongly affects shoot growth, possibly via “nonhydraulic messengers” from root to shoot. In short-term studies with barley (Hordeum vulgare L.) and sorghum (Sorghum bicolor L.) seedlings, the optimum root temperatures for leaf expansion were 25° and 35°C, respectively. Hydraulic conductance (Lp) of both intact plants and detached exuding roots of barley increased with increasing root temperature to a high value at 25°C, remaining high with further warming. In sorghum, the Lp of intact plants and of detached roots peaked at 35°C. In both species, root temperature did not affect water potentials of the expanded leaf blade or the growing region despite marked changes in Lp. Extreme temperatures greatly decreased ion flux, particularly K+ and NO3?, to the xylem of detached roots of both species. Removing external K+ did not alter short-term K+ flux to the xylem in sorghum but strongly inhibited flux at high temperature in barley, indicating differences in the sites of temperature effects. Leaf growth responses to root temperature, although apparently “uncoupled” from water transport properties, were correlated with ion fluxes. Studies of putative root messengers must take into account the possible role of ions. PMID:16668404

  4. Hollow silica sphere colloidal crystals: insights into calcination dependent thermal transport.

    PubMed

    Ruckdeschel, P; Kemnitzer, T W; Nutz, F A; Senker, J; Retsch, M

    2015-06-14

    Colloidal crystals consisting of monodisperse hollow silica spheres represent a well-defined porous material class, which features a range of interesting optical, mechanical, and thermal properties. These hierarchically structured materials comprise micropores within the silica network, which are confined to a thin shell (tens of nanometers) of a hollow sphere (hundreds of nanometers). Using simple calcination steps, we markedly change the internal microstructure, which we investigate by a multitude of characterization techniques, while the meso- and macrostructure remains constant. Most importantly the rearrangement of the silica condensation network leads to a reduction in the total surface area and loss of micropores as demonstrated by N2 sorption and hyperpolarized (129)Xe NMR studies. Spin-lattice relaxation shows a drastic increase of the rigidity of the amorphous network. These microstructural changes significantly influence the thermal conductivity through such a porous silica material. We demonstrate a remarkably low thermal conductivity of only 71 mW m(-1) K(-1) for a material of a comparatively high density of 1.04 kg m(-3) at 500 °C calcination temperature. This thermal conductivity increases up to 141 mW m(-1) K(-1) at the highest calcination temperature of 950 °C. The great strength of hollow silica sphere colloidal crystals lies in their hierarchical structure control, which allows further investigation of how the internal microstructure and the interfacial contact points affect the transport of heat. PMID:25978276

  5. Induction of the differentiation of HL-60 cells by phorbol 12-myristate 13-acetate activates a Na(+)-dependent uridine-transport system. Involvement of protein kinase C.

    PubMed Central

    Lee, C W; Sokoloski, J A; Sartorelli, A C; Handschumacher, R E

    1991-01-01

    The Na(+)-dependent transport and facilitated diffusion of uridine were measured after differentiation of HL-60 leukaemia cells along the monocytic pathway by phorbol 12-myristate 13-acetate (PMA). PMA (200 ng/ml) caused a marked increase in Na(+)-dependent uridine transport within 48 h of exposure that was attributable to an increase in transport affinity (apparent Km values of 1.15 +/- 0.22 and 44 +/- 4.4 microM for PMA-induced and uninduced cells respectively), with no change in Vmax. (0.15 +/- 0.02 and 0.13 +/- 0.01 pmol/s per microliter of cell water for PMA-induced and uninduced cells respectively). A corresponding rapid decrease in both the rate of facilitated diffusion and the formation of uracil nucleotides occurred in PMA-induced cells. As a consequence of these changes, intracellular pools of uridine 3-4-fold greater than those in the medium were generated. A similar increase in Na(+)-dependent transport of adenosine, inosine, guanosine, thymidine and cytidine (Km values of 1-4 microM) was observed. The effects of PMA on the activation of the Na(+)-dependent uridine transporter were inhibited by staurosporine, suggesting the involvement of protein kinase C. The findings indicate that a change in the balance of the cellular mechanisms employed for nucleoside transport occurs during the monocytic differentiation of HL-60 leukaemia cells. PMID:2001255

  6. Biotin uptake by T47D breast cancer cells: functional and molecular evidence of sodium-dependent multivitamin transporter (SMVT).

    PubMed

    Vadlapudi, Aswani Dutt; Vadlapatla, Ramya Krishna; Pal, Dhananjay; Mitra, Ashim K

    2013-01-30

    The objective of this study was to investigate functional and molecular evidence of carrier mediated system responsible for biotin uptake in breast cancer (T47D) cells and to delineate mechanism of intracellular regulation of this transporter. Cellular accumulation of [3H] biotin was studied in T47D and normal mammary epithelial (MCF-12A) cells. Reverse transcription polymerase chain reaction (RT-PCR) was carried out to confirm the molecular expression of sodium dependent multivitamin transporter (SMVT) in T47D cells. Quantitative real time PCR analysis was also performed to compare the relative expression of SMVT in T47D and MCF-12A cells. [3H] biotin uptake by T47D cells was found to be concentration dependent with K(m) of 9.24 ?M and V(max) of 27.34 pmol/mg protein/min. Uptake of [3H] biotin on MCF-12A cells was also found to be concentration dependent and saturable, but with a relatively higher K(m) (53.10 ?M) indicating a decrease in affinity of biotin uptake in normal breast cells compared to breast cancer cells. [3H] biotin uptake appears to be time-, temperature-, pH- and sodium ion-dependent but independent of energy and chloride ions. [3H] biotin uptake was significantly inhibited in the presence of biotin, its structural analog desthiobiotin, pantothenic acid and lipoic acid. Concentration dependent inhibition of biotin uptake was evident in the presence of valeric acid which possesses free carboxyl group and biocytin and NHS biotin which are devoid of free carboxyl group. No significant inhibition was observed in the presence of structurally unrelated vitamins (ascorbic acid, folic acid, nicotinic acid, thiamine, pyridoxine and riboflavin). Modulators of PTK, PKC and PKA mediated pathways had no effect, but uptake in presence of calmidazolium (calcium-calmodulin inhibitor) was significantly inhibited. [3H] biotin uptake in the presence of calmidazolium was found to be saturable with a K(m) and V(max) values of 13.49 ?M and 11.20 pmol/mg protein/min, respectively. A band of SMVT mRNA at 774 bp was identified by RT-PCR analysis. Quantitative real time PCR confirmed higher expression of SMVT in T47D cells relative to MCF-12A cells. All these studies demonstrated for the first time the functional and molecular expression of sodium dependent multivitamin transporter (SMVT), a specific carrier-mediated system for biotin uptake, in human derived breast cancer (T47D) cells. The present study also indicated that cancer cells could import more vitamin compared to normal breast cells possibly for maintaining high proliferative status. We investigated the likelihood of selecting this cell line (T47D) as an in vitro cell culture model to study biotin-conjugated anti-cancer drugs/drug delivery systems. PMID:23142496

  7. Sodium-dependent vitamin C transporter SVCT2: Expression and Function in bone marrow stromal cells and in Osteogenesis

    PubMed Central

    Fulzele, Sadanand; Chothe, Paresh; Sangani, Rajnikumar; Chutkan, Norman; Hamrick, Mark; Bhattacharyya, Maryka; Prasad, Puttur D.; Zakhary, Ibrahim; Bowser, Matthew; Isales, Carlos; Ganapathy, Vadivel

    2012-01-01

    Ascorbic acid (Vitamin C) has a critical role in bone formation and osteoblast differentiation, but very little is known about the molecular mechanisms of ascorbic acid entry into bone marrow stromal cells (BMSCs). To address this gap in knowledge, we investigated the identity of the transport system that is responsible for the uptake of ascorbic acid into bone marrow stromal cells (BMSCs). First, we examined the expression of the two known isoforms of the sodium-coupled ascorbic acid transporter, namely SVCT1 and SVCT2, in BMSCs (Lin-ve Sca1+ve) and bone at the mRNA level. Only SVCT2 mRNA was detected in BMSCs and bone. Uptake of ascorbic acid in BMSCs was Na+-dependent and saturable. In order to define the role of SVCT2 in BMSC differentiation into osteoblasts, BMSCs were stimulated with osteogenic media for different time intervals, and the activity of SVCT2 was monitored by ascorbic acid uptake. SVCT2 expression was up-regulated during the osteogenic differentiation of BMSCs; the expression was maximal at the earliest phase of differentiation. Subsequently, osteogenesis was inhibited in BMSCs upon knock-down of SVCT2 by lentivirus shRNA. We also found that the expression of the SVCT2 could be negatively or positively modulated by the presence of oxidant (Sin-1) or antioxidant (Ascorbic acid) compounds, respectively, in BMSCs. Furthermore, we found that this transporter is also regulated with age in mouse bone. These data show that SVCT2 plays a vital role in the osteogenic differentiation of BMSCs and that its expression is altered under conditions associated with redox reaction. Our findings could be relevant to bone tissue engineering and bone related diseases such as osteoporosis in which oxidative stress and aging plays important role. PMID:23089627

  8. Field and temperature dependent electron transport properties of random network single walled and multi walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Rajavel, K.; Verma, S.; Asokan, K.; Rajendra Kumar, R. T.

    2014-09-01

    Field and temperature dependent electron transport properties of random network single walled carbon nanotubes (SWCNTs) and multi walled carbon nanotubes (MWCNTs) were investigated and compared. The electrical characterizations of drop casted CNT samples were done by two probe measurements by varying temperatures from 80 K to 300 K in the field region 1-400 V cm-1. The charge transport mechanisms at low (<3.5 V) and high (>3.5 V) fields were analyzed from measured I-V characteristic curves at various temperatures (<300 K) with respect to applied field. At low field, the ohmic behavior was observed and at high field the charge transport appears to be Poole-Frenkel type in both types of CNTs network. Electron-electron and electron-phonon scatterings in the localized defect states dominate in SWCNTs, whereas in MWCNTs the delocalization of charge carriers as well as the scattering centers is responsible due to the presence of inner shells. Because of the different nature of chirality in random network, the SWCNTs displayed lower conduction when compared to MWCNTs. The variation in Poole-Frenkel co-efficient (?) (SWCNTs-0.193 × 10-22 MWCNTs-0.089 07 × 10-22 J V1/2 cm-1/2), activation energy (SWCNTs-90 meV; MWCNTs-60 meV for field of 7\\;{{V}^{1/2}}\\;c{{m}^{-1/2}}) and trap energy levels (SWCNTs-109 meV; MWCNTs-37 meV) are discussed for both SWCNTs and MWCNTs.

  9. Hollow silica sphere colloidal crystals: insights into calcination dependent thermal transport

    NASA Astrophysics Data System (ADS)

    Ruckdeschel, P.; Kemnitzer, T. W.; Nutz, F. A.; Senker, J.; Retsch, M.

    2015-05-01

    Colloidal crystals consisting of monodisperse hollow silica spheres represent a well-defined porous material class, which features a range of interesting optical, mechanical, and thermal properties. These hierarchically structured materials comprise micropores within the silica network, which are confined to a thin shell (tens of nanometers) of a hollow sphere (hundreds of nanometers). Using simple calcination steps, we markedly change the internal microstructure, which we investigate by a multitude of characterization techniques, while the meso- and macrostructure remains constant. Most importantly the rearrangement of the silica condensation network leads to a reduction in the total surface area and loss of micropores as demonstrated by N2 sorption and hyperpolarized 129Xe NMR studies. Spin-lattice relaxation shows a drastic increase of the rigidity of the amorphous network. These microstructural changes significantly influence the thermal conductivity through such a porous silica material. We demonstrate a remarkably low thermal conductivity of only 71 mW m-1 K-1 for a material of a comparatively high density of 1.04 kg m-3 at 500 °C calcination temperature. This thermal conductivity increases up to 141 mW m-1 K-1 at the highest calcination temperature of 950 °C. The great strength of hollow silica sphere colloidal crystals lies in their hierarchical structure control, which allows further investigation of how the internal microstructure and the interfacial contact points affect the transport of heat.Colloidal crystals consisting of monodisperse hollow silica spheres represent a well-defined porous material class, which features a range of interesting optical, mechanical, and thermal properties. These hierarchically structured materials comprise micropores within the silica network, which are confined to a thin shell (tens of nanometers) of a hollow sphere (hundreds of nanometers). Using simple calcination steps, we markedly change the internal microstructure, which we investigate by a multitude of characterization techniques, while the meso- and macrostructure remains constant. Most importantly the rearrangement of the silica condensation network leads to a reduction in the total surface area and loss of micropores as demonstrated by N2 sorption and hyperpolarized 129Xe NMR studies. Spin-lattice relaxation shows a drastic increase of the rigidity of the amorphous network. These microstructural changes significantly influence the thermal conductivity through such a porous silica material. We demonstrate a remarkably low thermal conductivity of only 71 mW m-1 K-1 for a material of a comparatively high density of 1.04 kg m-3 at 500 °C calcination temperature. This thermal conductivity increases up to 141 mW m-1 K-1 at the highest calcination temperature of 950 °C. The great strength of hollow silica sphere colloidal crystals lies in their hierarchical structure control, which allows further investigation of how the internal microstructure and the interfacial contact points affect the transport of heat. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr00435g

  10. Strain-dependent variations in visceral sensitivity: relationship to stress, anxiety and spinal glutamate transporter expression.

    PubMed

    Moloney, R D; Dinan, T G; Cryan, J F

    2015-04-01

    Responses to painful stimuli differ between populations, ethnic groups, sexes and even among individuals of a family. However, data regarding visceral pain are still lacking. Thus, we investigated differences in visceral nociception across inbred and outbred mouse strains using colorectal distension. Anxiety and depression-like behaviour were assessed using the open field and forced swim test as well as the corticosterone stress response. Possible mechanistic targets [excitatory amino acid transporter (EAAT-1), brain-derived neurotrophic factor (BDNF) and 5HT1A receptor] were also assessed using quantitative real-time polymerase chain reaction. Adult, male, inbred and outbred mouse strains were used in all assays (inbred strains; CBA/J Hsd, C3H/HeNHsd, BALB/c OlaHsd, C57 BL/6JOlaHsd, DBA/2J RccHsd, CAST/EiJ, SM/J, A/J OlaHsd, 129P2/OlaHsd, FVB/NHan Hsd and outbred strains: Swiss Webster, CD-1). mRNA expression levels of EAAT-1, BDNF and 5HT1A receptor (HTR1A) were quantified in the lumbosacral spinal cord, amygdala and hippocampus. A significant effect of strain was found in visceral sensitivity, anxiety and depressive-like behaviours. Strain differences were also seen in both baseline and stress-induced corticosterone levels. CBA/J mice consistently exhibited heightened visceral sensitivity, anxiety behaviour and depression-like behaviour which were associated with decreased spinal EAAT-1 and hippocampal BDNF and HTR1A. Our results show the CBA/J mouse strain as a novel mouse model to unravel the complex mechanisms of brain-gut axis disorders such as irritable bowel syndrome, in particular the underlying mechanisms of visceral hypersensitivity, for which there is great need. Furthermore, this study highlights the importance of genotype and the consequences for future development of transgenic strains in pain research. PMID:25851919

  11. Transport properties and Kondo correlations in nanostructures: Time-dependent DMRG method applied to quantum dots coupled to Wilson chains

    SciTech Connect

    Dias Da Silva, Luis G [ORNL; Heidrich-Meisner, Fabian [ORNL; Feiguin, Adrian E [ORNL; Busser, C. A. [Oakland University, Rochester, MI; Martins, G. B. [Oakland University, Rochester, MI; Anda, E. V. [Pontificia Universidade, Brazil; Dagotto, Elbio R [ORNL

    2008-01-01

    We apply the adaptive time-dependent density-matrix renormalization-group method tDMRG to the study of transport properties of quantum-dot systems connected to metallic leads. Finite-size effects make the usual tDMRG description of the Kondo regime a numerically demanding task. We show that such effects can be attenuated by describing the leads by Wilson chains, in which the hopping matrix elements decay exponentially away from the impurity tn n/2. For a given system size and in the linear-response regime, results for 1 show several improvements over the undamped =1 case: perfect conductance is obtained deeper in the strongly interacting regime and current plateaus remain well defined for longer time scales. Similar improvements were obtained in the finite-bias regime up to bias voltages of the order of the Kondo temperature. These results show that with the proposed modification, the tDMRG characterization of Kondo correlations in the transport properties can be substantially improved, while it turns out to be sufficient to work with much smaller system sizes. We discuss the numerical cost of this approach with respect to the necessary system sizes and the entanglement growth during the time evolution.

  12. Measuring Ligand-Dependent Transport in Nanopatterned PbS Colloidal Quantum Dot Arrays Using Charge Sensing.

    PubMed

    Ray, Nirat; Staley, Neal E; Grinolds, Darcy D W; Bawendi, Moungi G; Kastner, Marc A

    2015-07-01

    Colloidal quantum dot arrays with long organic ligands have better packing order than those with short ligands but are highly resistive, making low-bias conductance measurements impossible with conventional two-probe techniques. We use an integrated charge sensor to study transport in weakly coupled arrays in the low-bias regime, and we nanopattern the arrays to minimize packing disorder. We present the temperature and field dependence of the resistance for nanopatterned oleic-acid and n-butylamine-capped PbS arrays, measuring resistances as high as 10(18) ?. We find that the conduction mechanism changes from nearest neighbor hopping in oleic-acid-capped PbS dots to Mott's variable range hopping in n-butylamine capped PbS dots. Our results can be understood in terms of a change in the interdot coupling strength or a change in density of trap states and highlight the importance of the capping ligand on charge transport through colloidal quantum dot arrays. PMID:26044997

  13. The histidine transporter SLC15A4 coordinates mTOR-dependent inflammatory responses and pathogenic antibody production.

    PubMed

    Kobayashi, Toshihiko; Shimabukuro-Demoto, Shiho; Yoshida-Sugitani, Reiko; Furuyama-Tanaka, Kaori; Karyu, Hitomi; Sugiura, Yuki; Shimizu, Yukiko; Hosaka, Toshiaki; Goto, Motohito; Kato, Norihiro; Okamura, Tadashi; Suematsu, Makoto; Yokoyama, Shigeyuki; Toyama-Sorimachi, Noriko

    2014-09-18

    SLC15A4 is a lysosome-resident, proton-coupled amino-acid transporter that moves histidine and oligopeptides from inside the lysosome to the cytosol of eukaryotic cells. SLC15A4 is required for Toll-like receptor 7 (TLR7)- and TLR9-mediated type I interferon (IFN-I) productions in plasmacytoid dendritic cells (pDCs) and is involved in the pathogenesis of certain diseases including lupus-like autoimmunity. How SLC15A4 contributes to diseases is largely unknown. Here we have shown that B cell SLC15A4 was crucial for TLR7-triggered IFN-I and autoantibody productions in a mouse lupus model. SLC15A4 loss disturbed the endolysosomal pH regulation and probably the v-ATPase integrity, and these changes were associated with disruption of the mTOR pathway, leading to failure of the IFN regulatory factor 7 (IRF7)-IFN-I regulatory circuit. Importantly, SLC15A4's transporter activity was necessary for the TLR-triggered cytokine production. Our findings revealed that SLC15A4-mediated optimization of the endolysosomal state is integral to a TLR7-triggered, mTOR-dependent IRF7-IFN-I circuit that leads to autoantibody production. PMID:25238095

  14. Twisting motion dependent charge transport properties of poly(dG)-poly(dC) DNA molecular wire

    NASA Astrophysics Data System (ADS)

    Yudiarsah, E.; Suhendro, D. K.; Saleh, R.

    2014-09-01

    The effect of twisting motion of bases on charge transport properties of Poly(dG)-Poly(dC) DNA molecule have been studied. The effect is studied by taking into account twisting angle dependent on-site energy and hopping constant in the tight binding Hamiltonian of double-strand DNA model. The average kinetic energy of twisting motions is assumed to be proportional to system temperature. Transfer matrix method has been used in calculating the localization length of the molecule. The results show that increase in temperature shortens the localization length. The transmission probability of charge on the molecule was calculated using transfer and scattering matrix methods simultaneously on the DNA model sandwiched in between two metallic electrodes. The contacts between molecule and both electrodes were chosen such that the presence of metallic electrodes does not change the main features of transport properties of the molecule much. The temperature tends to widen the area with zero transmission around the Fermi energy. The I-V characteristic of the molecule connected to electrodes has been calculated from transmission probability within Landauer-Buttiker Formalism by assuming the voltage drops symmetrically at the contacts. The results show that temperature lowers the magnitude of the I-V characteristic and the differential conductance. In addition to that, the I-V characteristic and the differential conductance also decrease in magnitude with lowering the twisting frequency.

  15. Time Dependent Simulation of Energetic Ion Tail Formation Coupled to Thermal Plasma Transport

    NASA Astrophysics Data System (ADS)

    Batchelor, D. B.; Berry, L. A.; Bernholdt, D. E.; Elwasif, W.; Jaeger, E. F.; Lynch, V. E.; Harvey, R. W.; Bader, A.; Bonoli, P. T.; Jardin, S. C.; Ku, L.-P.

    2008-11-01

    Energetic ion populations have long been observed in tokamak plasmas heated by high power electromagnetic waves in the ion cyclotron range of frequencies. Previous self-consistent simulations [1] of these tails have involved iteration between an RF field solver and a Fokker-Planck solver to find stationary field and particle distributions assuming fixed thermal plasma profiles. Now, using the SWIM Integrated Plasma Simulator framework to couple the AORSA full-wave RF code, the CQL3D Fokker-Planck solver and the TSC tokamak simulation code, we are able to perform time-dependent simulations describing the evolution of the tail population including its effect on heating of the thermal plasma. Comparison will be presented with charge exchange neutral particle analysis measurements on Alcator C-Mod. [1] E.F. Jaeger, L.A. Berry, S.D. Ahern, et al., Phys. Plasmas 13, 056101-1 (2006).

  16. Spin-dependent thermal transport perpendicular to the planes of Co/Cu multilayers

    NASA Astrophysics Data System (ADS)

    Kimling, Johannes; Wilson, R. B.; Rott, Karsten; Kimling, Judith; Reiss, Günter; Cahill, David G.

    2015-04-01

    We report measurements of the cross-plane thermal conductivity of periodic Co/Cu multilayers using time-domain thermoreflectance. The cross-plane thermal conductivity increases from ˜18 W m-1K-1 at remanence to ˜32 W m-1K-1 at saturation fields. This giant magnetothermal resistance (GMTR) effect is consistent with predictions based on the Wiedemann-Franz law. We discuss the role of a spin-dependent temperature, known as spin heat accumulation, in GMTR experiments and develop a three-temperature model capable of predicting the time evolution of the temperatures of majority-spin electrons, minority-spin electrons, and phonons subsequent to pulsed laser heating.

  17. Phase-dependent exciton transport and energy harvesting from thermal environments

    E-print Network

    Oviedo-Casado, S; Chin, A W; Rosenbach, R; Huelga, S F; Plenio, M B

    2015-01-01

    Non-Markovian effects in the evolution of open quantum systems have recently attracted widespread interest, particularly in the context of assessing the efficiency of energy and charge transfer in nanoscale biomolecular networks and quantum technologies. With the aid of many-body simulation methods, we uncover and analyse an ultrafast environmental process that causes energy relaxation in the reduced system to depend explicitly on the phase relation of the initial state preparation. Remarkably, for particular phases and system parameters, the net energy flow is uphill, transiently violating the principle of detailed balance, and implying that energy is spontaneously taken up from the environment. A theoretical analysis reveals that non-secular contributions, significant only within the environmental correlation time, underlie this effect. This suggests that environmental energy harvesting will be observable across a wide range of coupled quantum systems.

  18. Phase-dependent exciton transport and energy harvesting from thermal environments

    E-print Network

    S. Oviedo-Casado; J. Prior; A. W. Chin; R. Rosenbach; S. F. Huelga; M. B. Plenio

    2015-06-26

    Non-Markovian effects in the evolution of open quantum systems have recently attracted widespread interest, particularly in the context of assessing the efficiency of energy and charge transfer in nanoscale biomolecular networks and quantum technologies. With the aid of many-body simulation methods, we uncover and analyse an ultrafast environmental process that causes energy relaxation in the reduced system to depend explicitly on the phase relation of the initial state preparation. Remarkably, for particular phases and system parameters, the net energy flow is uphill, transiently violating the principle of detailed balance, and implying that energy is spontaneously taken up from the environment. A theoretical analysis reveals that non-secular contributions, significant only within the environmental correlation time, underlie this effect. This suggests that environmental energy harvesting will be observable across a wide range of coupled quantum systems.

  19. Anisotropy and Temperature Dependence of Myoglobin Translational Diffusion in Myocardium: Implication for Oxygen Transport and Cellular Architecture

    PubMed Central

    Lin, Ping-Chang; Kreutzer, Ulrike; Jue, Thomas

    2007-01-01

    Pulsed field gradient NMR methods have determined the temperature-dependent diffusion of myoglobin (Mb) in perfused rat myocardium. Mb diffuses with an averaged translational diffusion coefficient (DMb) of 4.24–8.37 × 10?7cm2/s from 22°C to 40°C and shows no orientation preference over a root mean-square displacement of 2.5–3.5 ?m. The DMb agrees with the value predicted by rotational diffusion measurements. Based on the DMb, the equipoise diffusion PO2, the PO2 in which Mb-facilitated and free O2 diffusion contribute equally to the O2 flux, varies from 2.72 to 0.15 in myocardium and from 7.27 to 4.24 mmHg in skeletal muscle. Given the basal PO2 of ?10 mmHg, the Mb contribution to O2 transport appears insignificant in myocardium. In skeletal muscle, Mb-facilitated diffusion begins to contribute significantly only when the PO2 approaches the P50. In marine mammals, the high Mb concentration confers a predominant role for Mb in intracellular O2 transport under all physiological conditions. The Q10 of the DMb ranges from 1.3 to 1.6. The Mb diffusion data indicate that the postulated gel network in the cell must have a minimum percolation cutoff size exceeding 17.5 Å and does not impose tortuosity within the diffusion root mean-square displacement. Moreover, the similar Q10 for the DMb of solution versus cell Mb suggests that any temperature-dependent alteration of the postulated cell matrix does not significantly affect protein mobility. PMID:17218454

  20. Structure-function activity of the human sodium-dependent multivitamin transporter: role of His¹¹? and His²??.

    PubMed

    Ghosal, Abhisek; Said, Hamid M

    2011-01-01

    Intestinal absorption of biotin occurs via a Na(+)-dependent carrier-mediated process that involves the sodium-dependent multivitamin transporter (SMVT; product of the Slc5a6 gene). The SMVT system is exclusively expressed at the apical membrane domain of the polarized intestinal epithelial cells. Whereas previous studies from our laboratory and others have characterized different physiological and biological aspects of SMVT, little is currently known about its structure-function activity relationship. Using site-directed mutagenesis approach, we examined the role of the positively charged histidine (His) residues of the human SMVT (hSMVT) in transporting the negatively charged biotin. Of the seven conserved (across species) His residues in the hSMVT polypeptide, only His¹¹? and His²?? were found to be important for the function of hSMVT as their mutation led to a significant reduction in carrier-mediated biotin uptake. This inhibition was mediated via a significant reduction in the maximal velocity (V(max)), but not the apparent Michaelis constant (K(m)), of the biotin uptake process and was not related to the charge of the His residue. The inhibition was also not due to changes in transcriptional or translational efficiency of the mutated hSMVT compared with wild-type carrier. However, surface biotinylation assay showed a significant reduction in the level of expression of the mutated hSMVT at the cell surface, a finding that was further confirmed by confocal imaging. Our results show important role for His¹¹? and His²?? residues in hSMVT function, which is most probably mediated via an effect on level of hSMVT expression at the cell membrane. PMID:20962270

  1. Oxygen Dependence and Extravascular Transport of Hypoxia-Activated Prodrugs: Comparison of the Dinitrobenzamide Mustard PR-104A and Tirapazamine

    SciTech Connect

    Hicks, Kevin O. [Auckland Cancer Society Research Centre, University of Auckland School of Medical Sciences, Auckland (New Zealand)], E-mail: k.hicks@auckland.ac.nz; Myint, Hilary; Patterson, Adam V.; Pruijn, Frederik B.; Siim, Bronwyn G.; Patel, Kashyap; Wilson, William R. [Auckland Cancer Society Research Centre, University of Auckland School of Medical Sciences, Auckland (New Zealand)

    2007-10-01

    Purpose: To compare oxygen dependence and tissue transport properties of a new hypoxia-activated prodrug, PR-104A, with tirapazamine, and to evaluate the implications for antitumor activity when combined with radiotherapy. Methods and Materials: Oxygen dependence of cytotoxicity was measured by clonogenic assay in SiHa cell suspensions. Tissue transport parameters were determined using SiHa multicellular layers. Spatially resolved pharmacokinetic (PK) and pharmacodynamic (PD) models were developed to predict cell killing in SiHa tumors and tested by clonogenic assay 18 h after treatment with the corresponding phosphate ester, PR-104. Results: The K-value (oxygen concentration to halve cytotoxic potency) of PR-104A was 0.126 {+-} 0.021 {mu}M (10-fold lower than tirapazamine at 1.30 {+-} 0.28 {mu}M). The diffusion coefficient of PR-104A in multicellular layers (4.42 {+-} 0.15 x 10{sup -7} cm{sup 2} s{sup -1}) was lower than that of tirapazamine (1.30 {+-} 0.05 x 10{sup -6} cm{sup 2} s{sup -1}) but PK modeling predicted better penetration to hypoxic cells in tumors because of its slower metabolism. The tirapazamine PK/PD model successfully predicted the measured activity in combination with single-dose radiation against SiHa tumors, and the PR-104A model underpredicted the activity, which was greater for PR-104 than for tirapazamine (at equivalent host toxicity) both with radiation and as a single agent. Conclusion: PR-104/PR-104A has different PK/PD properties from tirapazamine and superior activity with single-dose radiotherapy against SiHa xenografts. We have inferred that PR-104A is better able to kill cells at intermediate partial pressure of oxygen in tumors than implied by the PK/PD model, most likely because of a bystander effect resulting from diffusion of its activated metabolites from severely hypoxic zones.

  2. Azimuthal anisotropy in the D? layer beneath the Caribbean

    NASA Astrophysics Data System (ADS)

    Maupin, ValéRie; Garnero, Edward J.; Lay, Thorne; Fouch, Matthew J.

    2005-08-01

    The lowermost mantle beneath Central America has anisotropic seismic velocity structure manifested in shear wave splitting of signals from South American earthquakes recorded at North American broadband recording stations. Prior studies of deep mantle anisotropy in this region have characterized the structure as having vertical transverse isotropy (VTI), which is sufficient to explain a general trend of early tangential (SH) component arrivals. However, VTI models cannot quantitatively match systematic waveform complexities in the onset of many of the shear waves that graze this region. After accounting for splitting effects of upper mantle anisotropy beneath the recording stations, we model the corrected waveform data using full wave theory for mantle velocity models with an anisotropic D? layer. This is the first attempt to quantitatively model a large data set including azimuthal anisotropy in D?. The models include transverse isotropy with either a vertical or tilted symmetry axis, the latter resulting in azimuthal anisotropy. For some initial shear wave polarizations, tilted transverse isotropy (TTI) produces small, reversed polarity arrivals on the SV components at the arrival time of SH, consistent with the data. Geographical variations in the azimuth of the TTI symmetry axis are indicated by the data. The lack of azimuthal coverage prevents unique resolution of the TTI orientation and also precludes distinguishing between TTI and other azimuthal anisotropy structures such as that predicted for lattice preferred orientation of minerals. Nonetheless, our modeling demonstrates the need for laterally varying anisotropic structure of more complex form than VTI for this region.

  3. Strong azimuthal anchoring energy at a nematic-polyimide interface.

    PubMed

    Faetti, S; Marianelli, P

    2005-11-01

    Some years ago we proposed an automated reflectometric method to measure the director azimuthal angle at the interface between a nematic liquid crystal and another medium. The method ensures a great accuracy and sensitivity and is virtually unaffected by the presence of a director bulk distortion. This latter property makes it possible to measure strong anchoring energies. In the present experiment, we use this method to measure the azimuthal anchoring energy at the interface between the nematic liquid crystal 4-pentyl-4-cyanobiphenyl (5CB) and a rubbed polyimide layer. This kind of interface is characterized by a strong azimuthal anchoring and, thus, it represents a good test for the proposed reflectometric method. An ac planar electric field is applied to a nematic layer and the consequent azimuthal rotation of the director at the interface is measured. The anchoring energy coefficient Wa at room temperature is strong (Wa=0.33 x 10(-3) J/m2) and decreases greatly as the clearing temperature is approached. The time response of the azimuthal surface director angle to a stepwise electric field evidences the characteristic slow dynamics which is currently observed for weak anchoring substrates. PMID:16383621

  4. Concentration Dependent Speciation and Mass Transport Properties of Switchable Polarity Solvents

    SciTech Connect

    Aaron D. Wilson; Christopher J. Orme

    2014-12-01

    Tertiary amine switchable polarity solvents (SPS) consisting of predominantly water, tertiary amine, and tertiary ammonium and bicarbonate ions were produced at various concentrations for three different amines: N,N-dimethylcyclohexylamine, N,N-dimethyloctylamine, and 1 cyclohexylpiperidine. For all concentrations, physical properties were measured including viscosity, molecular diffusion coefficients, freezing point depression, and density. Based on these measurements a variation on the Mark Houwink equation was developed to predict the viscosity of any tertiary amine SPS as a function of concentration using the amine’s molecular mass. The observed physical properties allowed the identification of solution state speciation of non-osmotic SPS, where the amine to carbonic acid ratio is significantly greater than one. These results indicate that at most concentrations the stoichiometric excess amine is involved in solvating a proton with two amines. The physical properties of osmotic SPS have consistent concentration dependence behavior over a wide range of concentrations; this consistence suggests osmotic pressures based on low concentrations freezing point studies can be reliably extrapolated to higher concentrations.

  5. Genetic Variation in Sodium-Dependent Vitamin C Transporters SLC23A1 and SLC23A2 and Risk of Advanced Colorectal Adenoma

    Microsoft Academic Search

    Hans Christian Erichsen; Ulrike Peters; Peter Eck; Robert Welch; Robert E. Schoen; Meredith Yeager; Mark Levine; Richard B. Hayes; Stephen Chanock

    2008-01-01

    Previous observational studies suggest that vitamin C may reduce risk of colorectal cancer. Vitamin C transport is facilitated by membrane bound sodium-dependent transporters, SVCT1 (encoded by SLC23A1) and SVCT2 (encoded by SLC23A2). To investigate if common genetic variants in these two genes are associated with risk of colorectal tumor development, we conducted a case-control study of 656 Caucasian advanced distal

  6. Synthesis and Biologic Evaluation of 11C-Methyl- D-Glucoside, a Tracer of the Sodium-Dependent Glucose Transporters

    Microsoft Academic Search

    Guy M. Bormans; Griet Van Oosterwyck; Tjibbe J. de Groot; Maike Veyhl; Luc Mortelmans; Alfons M. Verbruggen; Hermann Koepsell

    This study aimed to synthesize and to evaluate the biologic characteristics of 11C labeled methyl-D-glucoside, a nonme- tabolizable tracer that is selectively transported by sodium- dependent glucose transporters (SGLTs). Methods: 11C-Meth- yl-D-glucoside was prepared by methylation of glucose with 11C-methyl triflate and was obtained as a mixture of anomers that were separated with high-performance liquid chromatog- raphy. The biodistribution of

  7. Higher harmonics of azimuthal anisotropy in relativistic heavy ion collisions in HYDJET++ model

    E-print Network

    L. V. Bravina; B. H. Brusheim Johansson; G. Kh. Eyyubova; V. L. Korotkikh; I. P. Lokhtin; L. V. Malinina; S. V. Petrushanko; A. M. Snigirev; E. E. Zabrodin

    2014-03-04

    The LHC data on azimuthal anisotropy harmonics from PbPb collisions at center-of-mass energy 2.76 TeV per nucleon pair are analyzed and interpreted in the framework of the HYDJET++ model. The cross-talk of elliptic $v_2$ and triangular $v_3$ flow in the model generates both even and odd harmonics of higher order. Comparison with the experimental data shows that this mechanism is able to reproduce the $p_{\\rm T}$ and centrality dependencies of quadrangular flow $v_4$, and also the basic trends for pentagonal $v_5$ and hexagonal $v_6$ flows.

  8. Phenomenological analysis of azimuthal asymmetries in unpolarized semi-inclusive deep inelastic scattering

    NASA Astrophysics Data System (ADS)

    Barone, V.; Boglione, M.; Gonzalez Hernandez, J. O.; Melis, S.

    2015-04-01

    We present a phenomenological analysis of the cos ? and cos 2 ? asymmetries in unpolarized semi-inclusive deep inelastic scattering, based on the recent multidimensional data released by the COMPASS and HERMES collaborations. In the transverse-momentum-dependent framework, valid at relatively low transverse momenta, these asymmetries arise from intrinsic transverse momentum and transverse spin effects, and from their correlations. The role of the Cahn and Boer-Mulders effects in both azimuthal moments is explored up to order 1 /Q . As the kinematics of the present experiments is dominated by the low-Q2 region, higher-twist contributions turn out to be important, affecting the results of our fits.

  9. Azimuthal Directivity of Fan Tones Containing Multiple Modes

    NASA Technical Reports Server (NTRS)

    Heidelberg, Laurence J.; Sutliff, Daniel L.; Nallasamy, M.

    1997-01-01

    The directivity of fan tone noise is generally measured and plotted in the sideline or flyover plane and it is assumed that this curve is the same for all azimuthal angles. When two or more circumferential (m-order) modes of the same tone are present in the fan duct, an interference pattern develops in the azimuthal direction both in the duct and in the farfield. In this investigation two m-order modes of similar power were generated in a large low speed fan. Farfield measurements and a finite element propagation code both show substantial variations in the azimuthal direction. Induct mode measurement were made and used as input to the code. Although these tests may represent a worst case scenario, the validity of the current practice of assuming axisymmetry should be questioned.

  10. Spin-dependent transport and current-induced spin transfer torque in a strained graphene spin valve

    NASA Astrophysics Data System (ADS)

    Ding, Kai-He; Zhu, Zhen-Gang; Su, Gang

    2014-05-01

    Using the nonequilibrium Green's function method, we investigated theoretically the spin-dependent transport and the current-induced spin transfer torque (CISTT) in a zigzag-graphene-nanoribbon (ZGNR) spin valve in the presence of an applied uniaxial strain to the ZGNR. It is found that, when a longitudinal or transverse strain is applied, the conductance versus the Fermi energy remains unchanged around the Dirac point. However, when the Fermi energy is larger than the molecular field of two ferromagnetic electrodes, the dependence of the conductance on the uniaxial strain exhibits totally different behaviors for parallel and antiparallel configurations for the electrodes' magnetizations, which leads to a transition of magnetoresistance (MR) from a perfect histogramlike behavior to successive cusplike peaks and to a steplike behavior with sharp peaks for the longitudinal and transverse strains, respectively. It is further shown that the CISTT per unit of the bias voltage as a function of the Fermi energy is antisymmetric respective to the Dirac point and exhibits typical successive oscillations composed of broad peaks closely followed by sharp ones.

  11. Incidence Angle-dependent Transport across a Single Graphene p-n Junction Formed by Buried Split-gates

    NASA Astrophysics Data System (ADS)

    Sutar, Surajit; Comfort, Everett; Liu, Jian; Taniguchi, Takashi; Watanabe, Kenji; Lee, Ji Ung

    2012-02-01

    Due to electron chirality effects, carrier transport across Graphene p-n junctions (GPNJ) is predicted to have strong angular dependence [1]. This work reports evidence of such effects in a single GPNJ for various geometries created by the use of buried split-gates (SG). Standard processes are used to fabricate 2-terminal Graphene devices aligned to buried Polysilicon SG at different angles to the junction. Sweeping the SG biases V1 and V2 allows mapping the doping-dependent device resistance (Rt). For doping levels (V1,V2), subtracting the average unipolar resistance Rt(V1,V1) from the bipolar resistance Rt(V1,V2) gives the average junction resistance Rj(V1,V2), subtracting out both contact and channel resistances. For bipolar doping, Rj shows a sharper peak for tilted channels than one that is normal to the junction, the peak being sharpest for 45 , the largest angle probed. This trend is observed for both exfoliated and CVD Graphene, especially for higher mobility and lower widths, consistent with theory. The ratio of the maximal Rj for 45 and 0 devices is about 2.5, significant for the modest Graphene mobilities of our devices. [1] V. Cheianov et al., Science, 315, 2007, pp 1252.

  12. Glucose and fructose uptake by Limulus polyphemus hepatopancreatic brush border and basolateral membrane vesicles: evidence for Na+-dependent sugar transport activity.

    PubMed

    Sterling, Kenneth M; Ahearn, Gregory A

    2011-05-01

    [(3)H]-fructose and [(3)H]-glucose transport activities were determined in brush border membrane vesicles (BBMV) and basolateral membrane vesicles (BLMV) from Limulus polyphemus (horseshoe crab) hepatopancreas. Glucose transport was equilibrative in the absence of sodium and sodium dependent in the presence of sodium in BBMV, suggesting GLUT-like and SGLT-like transport activity. Glucose transport by BLMV was equilibrative and sodium independent. Fructose uptake by BBMV and BLMV was equilibrative in the absence of sodium and sodium dependent in the presence of sodium. Western blot analysis using a rabbit anti-mouse SGLT-1 polyclonal antibody indicated the presence of a cross-reacting horseshoe crab BBMV protein of similar molecular weight to the mammalian SGLT1. Sequence alignment of the mouse SGLT-4 and SGLT1 with a translated, horseshoe crab-expressed sequence tag also indicated significant identity between species. Fructose and glucose uptake in the absence and presence of sodium by hepatopancreas BBMV and BLMV indicated the presence of sodium-dependent transport activity for each sugar that may result from the presence of transporters similar to those described for other species. PMID:21184084

  13. Anion-dependent transport of thallous ions through human erythrocyte membrane.

    PubMed

    Skulskii, I A; Gusev, G P; Sherstobitov, A O; Manninen, V

    1992-12-01

    Undirectional fluxes of 204Tl+ through the human red blood cell membrane were measured. The inward rate coefficient measured in a K(+)-free saline was 15.6 +/- 0.6 hr-1. The influx of Tl+ could be partially inhibited with 0.1 mM ouabain (by 28%), 0.1 mM DIDS (by 50%) or 1 mM furosemide (by 51%). The inhibitory effects of ouabain and DIDS or furosemide were additive. Half-maximal responses were seen at 0.72 microM and 0.22 mM concentrations of DIDS and furosemide, respectively. A similar action of these blockers on Tl+ influx was observed in the erythrocytes incubated in MgCl2-sucrose media. The outward rate coefficient of 204Tl was also inhibited by DIDS and furosemide (by 65 and 52%, respectively). Rate coefficients of 204Tl influx and efflux decreased significantly in the red cells exposed to Cl(-)-free media (NaNO3 or Mg(NO3)2-sucrose). Under these conditions addition of DIDS and furosemide led to only a small inhibition of Tl+ fluxes. There was a linear increase in Tl+ influx with rising of external Cl- concentration within 80-155 mM or HCO3- concentration from 20 to 40 mM when the sum of anions was kept constant (155 mM) with NO3-. The HCO3(-)-stimulated Tl+ influx was completely blocked by 0.05 mM DIDS but only 67% by 1 mM furosemide. The present study provides direct evidence for the occurrence of Cl- (HCO3-)-dependent, DIDS-sensitive movement of Tl+ across the human erythrocyte membrane in both directions. Under physiological conditions, about half of net Tl+ fluxes occurs due to an anion exchange mechanism.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1491427

  14. Age- and sex-dependent susceptibility to phenobarbital-resistant neonatal seizures: role of chloride co-transporters.

    PubMed

    Kang, Seok Kyu; Markowitz, Geoffrey J; Kim, Shin Tae; Johnston, Michael V; Kadam, Shilpa D

    2015-01-01

    Ischemia in the immature brain is an important cause of neonatal seizures. Temporal evolution of acquired neonatal seizures and their response to anticonvulsants are of great interest, given the unreliability of the clinical correlates and poor efficacy of first-line anti-seizure drugs. The expression and function of the electroneutral chloride co-transporters KCC2 and NKCC1 influence the anti-seizure efficacy of GABAA-agonists. To investigate ischemia-induced seizure susceptibility and efficacy of the GABAA-agonist phenobarbital (PB), with NKCC1 antagonist bumetanide (BTN) as an adjunct treatment, we utilized permanent unilateral carotid-ligation to produce acute ischemic-seizures in post-natal day 7, 10, and 12 CD1 mice. Immediate post-ligation video-electroencephalograms (EEGs) quantitatively evaluated baseline and post-treatment seizure burdens. Brains were examined for stroke-injury and western blot analyses to evaluate the expression of KCC2 and NKCC1. Severity of acute ischemic seizures post-ligation was highest at P7. PB was an efficacious anti-seizure agent at P10 and P12, but not at P7. BTN failed as an adjunct, at all ages tested and significantly blunted PB-efficacy at P10. Significant acute post-ischemic downregulation of KCC2 was detected at all ages. At P7, males displayed higher age-dependent seizure susceptibility, associated with a significant developmental lag in their KCC2 expression. This study established a novel neonatal mouse model of PB-resistant seizures that demonstrates age/sex-dependent susceptibility. The age-dependent profile of KCC2 expression and its post-insult downregulation may underlie the PB-resistance reported in this model. Blocking NKCC1 with low-dose BTN following PB treatment failed to improve PB-efficacy. PMID:26029047

  15. Age- and sex-dependent susceptibility to phenobarbital-resistant neonatal seizures: role of chloride co-transporters

    PubMed Central

    Kang, Seok Kyu; Markowitz, Geoffrey J.; Kim, Shin Tae; Johnston, Michael V.; Kadam, Shilpa D.

    2015-01-01

    Ischemia in the immature brain is an important cause of neonatal seizures. Temporal evolution of acquired neonatal seizures and their response to anticonvulsants are of great interest, given the unreliability of the clinical correlates and poor efficacy of first-line anti-seizure drugs. The expression and function of the electroneutral chloride co-transporters KCC2 and NKCC1 influence the anti-seizure efficacy of GABAA-agonists. To investigate ischemia-induced seizure susceptibility and efficacy of the GABAA-agonist phenobarbital (PB), with NKCC1 antagonist bumetanide (BTN) as an adjunct treatment, we utilized permanent unilateral carotid-ligation to produce acute ischemic-seizures in post-natal day 7, 10, and 12 CD1 mice. Immediate post-ligation video-electroencephalograms (EEGs) quantitatively evaluated baseline and post-treatment seizure burdens. Brains were examined for stroke-injury and western blot analyses to evaluate the expression of KCC2 and NKCC1. Severity of acute ischemic seizures post-ligation was highest at P7. PB was an efficacious anti-seizure agent at P10 and P12, but not at P7. BTN failed as an adjunct, at all ages tested and significantly blunted PB-efficacy at P10. Significant acute post-ischemic downregulation of KCC2 was detected at all ages. At P7, males displayed higher age-dependent seizure susceptibility, associated with a significant developmental lag in their KCC2 expression. This study established a novel neonatal mouse model of PB-resistant seizures that demonstrates age/sex-dependent susceptibility. The age-dependent profile of KCC2 expression and its post-insult downregulation may underlie the PB-resistance reported in this model. Blocking NKCC1 with low-dose BTN following PB treatment failed to improve PB-efficacy. PMID:26029047

  16. Range ambiguity suppression for multiple-input, multiple-output synthetic aperture radar system using azimuth phase coding technique

    NASA Astrophysics Data System (ADS)

    Guo, Lei; Wang, Robert; Deng, Yunkai; Wang, Wei; Luo, Xiulian

    2014-01-01

    For synthetic aperture radar (SAR), range ambiguity causes a great deterioration in imaging performance. To suppress range ambiguity, the azimuth phase coding (APC) technique stands out for its effectiveness with a low implementation complexity among the available approaches. With proper phase modulation and demodulation, the position of an ambiguous signal is shifted in Doppler spectrum and then part of the ambiguity can be filtered out by an azimuth filter. However, since the suppression performance heavily depends on the system oversampling rate, the APC technique cannot achieve the same suppression performance for a multichannel SAR system compared with a single-channel SAR system. A method to suppress the range ambiguity for multiple-input, multiple-output (MIMO) SAR system based on APC technique is presented. By taking advantage of more phase centers of the MIMO SAR, a proper azimuth beamformer weight vector can be computed to null out the ambiguity position in the azimuth frequency domain and reconstruct the useful signal; thus most of the ambiguity components can be significantly suppressed. Finally, the simulation results validate the effectiveness of the proposed method.

  17. Azimuthal auroral expansion associated with fast flows in the near-Earth plasma sheet: Coordinated observations of the THEMIS all-sky imagers and multiple spacecraft

    NASA Astrophysics Data System (ADS)

    Ogasawara, K.; Kasaba, Y.; Nishimura, Y.; Hori, T.; Takada, T.; Miyashita, Y.; Angelopoulos, V.; Mende, S. B.; Bonnell, J.

    2011-06-01

    Fast azimuthal auroral expansion and poleward expansion are characteristic features of the expansion phase of substorms. In the first study of its kind, we have investigated the azimuthal auroral expansion and its magnetospheric counterpart using data from Time History of Events and Macroscale Interactions during Substorms (THEMIS) all-sky imagers and multiple spacecraft. During the tail season in 2008-2009, we found 16 events of azimuthally expanding aurora that passed near the magnetic footprints of the multiple spacecraft operating in the near-Earth plasma sheet. In the magnetosphere, these events commonly showed fast azimuthal and earthward flows associated with intense electric fields and magnetic dipolarization. The speed of the propagating structure, which was estimated from the time difference of the depolarization observed by the multiple spacecraft, was close to the measured azimuthal plasma flow velocity. We also found that this azimuthal plasma transport was dominated by the E × B drift speed associated with the enhanced electric field. In a statistical analysis, the averaged speeds of the leading edge of the westward and eastward auroral expansion were 8.8 and 5.3 km/s, respectively. When mapped onto the equatorial magnetosphere, these speeds (267 and 162 km/s) were comparable to the averaged azimuthal plasma (E × B) flow speeds observed by the spacecraft, which were 193 (239) km/s in the westward direction and 112 (139) km/s in the eastward direction. Our events showed that E × B flows and auroral expansion predominantly propagated westward, indicating an effect of westward background convection in the Harang flow shear. From these results, we concluded that the azimuthal auroral expansion was closely related to magnetic dipolarization which expanded azimuthally at the E × B drift speed. On the basis of the abrupt formation of the fast E × B flows and their propagation away from the onset location, we suggest that the effects of the intense large-scale electric fields, which are possibly generated through substorm onset turbulence, propagate to the ionosphere along the magnetic field lines and lead to azimuthal expansion of an auroral arc.

  18. A Human Sodium-Dependent Vitamin C Transporter 2 Isoform Acts as a Dominant-Negative Inhibitor of Ascorbic Acid Transport

    Microsoft Academic Search

    Eugene A. Lutsenko; Juan M. Carcamo; David W. Golde

    2004-01-01

    Vitamin C is transported as ascorbic acid (AA) through the sodium-ascorbate cotransporters (SVCT1 and -2) and as dehydroascorbic acid (DHA) through the facilitative glucose transporters. All cells have glucose transporters and take up DHA that is trapped intracellularly by reduction and accumulated as AA. SVCT2 is widely expressed in cells and tissues at the mRNA level; however, only specialized cells

  19. Spin dependent transport studies in magnetic, non-magnetic, antiferromagnetic, and half metals

    NASA Astrophysics Data System (ADS)

    Acharyya, Rakhi

    This thesis consists of three studies of Current-Perpendicular-to-the-Planes (CPP) Magnetoresistance (MR) of sputtered ferromagnetic/non-magnetic (F/N) multilayers. (a) The first study involves a double-blind comparison of our measurements of the interface specific resistance AR (area A through which the CPP current flows times the CPP resistance R) of Pd/Ir interfaces with no-free-parameter calculations. (b) The second study is of spin relaxation within the antiferromagnets (AF) IrMn and FeMn and at their interfaces with Cu. (c) The third study is of the MR of multilayers involving a nominal half-metal Heusler alloy, Co2Fe(Al0.5Si0.5) (CFAS). A true half-metal should give an especially large CPP-MR. This study involves a different sample geometry, combining optical lithography and ion-beam etching, with epitaxial sputtering at elevated temperatures. (a) For four pairs of lattice-matched metals (Ag/Au, Co/Cu, Fe/Cr, and Pt/Pd) having the same crystal structure and the same lattice parameter to within ˜1%, no-free-parameter calculations of 2AR, twice the interface specific resistance AR have agreed with measured values to within mutual uncertainties. For three pairs, the measured values were known when the calculations were made. For the fourth pair, Pt/Pd, they were not. In contrast, calculations for non-matched pairs, where the lattice parameters differed by 5% or more, disagreed with measured values. In this thesis we study a fifth pair, Pd and Ir, where the lattice parameter mismatch is intermediate, 1.3%. The project was done double-blind with theory collaborators Wang and Xia, with experiment and calculations shared only after both groups settled on their separate values. The values for Pd/Ir calculated with the same assumptions used previously were just outside of uncertainty of the measured ones. An improved calculation gave agreement between the two values. (b) Antiferromagnets (AFs) play important roles in CPP-MR devices as sources of pinning for F-layers in exchange-biased spin-valves (EBSVs), and are also part of a burgeoning field of AF spintronics. For both structures, it is important to understand spin-relaxation within sputtered AFs and at AF/N interfaces. A prior study of spin-relaxation in sputtered FeMn found strong spin-flipping at FeMn/Cu interfaces, but was unable to determine the size of spin-flipping within the FeMn itself. In this thesis we find strong spin-flipping at IrMn/Cu interfaces and confirm strong spin-flipping at FeMn/Cu interfaces. We also discovered an interesting new phenomenon, a weak magnetic dependence of AR in Py, that makes us unable to put a tight bound on the bulk spin-diffusion lengths in sputtered IrMn or FeMn. But these lengths are probably short. (c) The CPP-MR of an F/N multilayer will be enhanced by an F-metal with high spin scattering asymmetry, making such a multilayer more competitive for devices. Half-metallic ferromagnetic metals, such as Heusler alloys, are predicted to have high asymmetry. Experiments with the Heusler alloy CFAS have shown both large Tunneling Magnetoresistance (TMR) and large CPP-MR for multilayers with non-superconducting electrodes sputtered at room temperature and then post-annealed to 500°C. In this thesis we attempt to optimize epitaxial growth using high temperature sputtering to produce highly ordered Heusler alloys grown on superconducting electrodes. We are able to grow CFAS epitaxially, but have obtained maximum CPP MR only about one-third (40%) as large as we expected.

  20. A FOCUSED TRANSPORT APPROACH TO THE TIME-DEPENDENT SHOCK ACCELERATION OF SOLAR ENERGETIC PARTICLES AT A FAST TRAVELING SHOCK

    SciTech Connect

    Le Roux, J. A.; Webb, G. M. [Department of Physics, University of Alabama in Huntsville, Huntsville, AL 35899 (United States)

    2012-02-10

    Some of the most sophisticated models for solar energetic particle (SEP) acceleration at coronal mass ejection driven shocks are based on standard diffusive shock acceleration theory. However, this theory, which only applies when SEP pitch-angle anisotropies are small, might have difficulty in describing first-order Fermi acceleration or the shock pre-heating and injection of SEPs into first-order Fermi acceleration accurately at lower SEP speeds where SEP pitch-angle anisotropies upstream near the shock can be large. To avoid this problem, we use a time-dependent focused transport model to reinvestigate first-order Fermi acceleration at planar parallel and quasi-parallel spherical traveling shocks between the Sun and Earth with high shock speeds associated with rare extreme gradual SEP events. The focused transport model is also used to investigate and compare three different shock pre-heating mechanisms associated with different aspects of the nonuniform cross-shock solar wind flow, namely, the convergence of the flow (adiabatic compression), the shear tensor of the flow, and the acceleration of the flow, and a fourth shock pre-heating mechanism associated with the cross-shock electric field, to determine which pre-heating mechanism contributes the most to injecting shock pre-heated source particles into the first-order Fermi acceleration process. The effects of variations in traveling shock conditions, such as increasing shock obliquity and shock slowdown, and variations in the SEP source with increasing shock distance from the Sun on the coupled processes of shock pre-heating, injection, and first-order Fermi acceleration are analyzed. Besides the finding that the cross-shock acceleration of the solar wind flow yields the dominant shock pre-heating mechanism at high shock speeds, we find that first-order Fermi acceleration at fast traveling shocks differs in a number of respects from the predictions and assumptions of standard steady-state diffusive shock acceleration theory as is discussed below.

  1. Transportation of Aspergillus nidulans Class III and V Chitin Synthases to the Hyphal Tips Depends on Conventional Kinesin

    PubMed Central

    Takeshita, Norio; Wernet, Valentin; Tsuizaki, Makusu; Grün, Nathalie; Hoshi, Hiro-omi; Ohta, Akinori; Fischer, Reinhard; Horiuchi, Hiroyuki

    2015-01-01

    Cell wall formation and maintenance are crucial for hyphal morphogenesis. In many filamentous fungi, chitin is one of the main structural components of the cell wall. Aspergillus nidulans ChsB, a chitin synthase, and CsmA, a chitin synthase with a myosin motor-like domain (MMD) at its N-terminus, both localize predominantly at the hyphal tip regions and at forming septa. ChsB and CsmA play crucial roles in polarized hyphal growth in A. nidulans. In this study, we investigated the mechanism by which CsmA and ChsB accumulate at the hyphal tip in living hyphae. Deletion of kinA, a gene encoding conventional kinesin (kinesin-1), impaired the localization of GFP-CsmA and GFP-ChsB at the hyphal tips. The transport frequency of GFP-CsmA and GFP-ChsB in both anterograde and retrograde direction appeared lower in the kinA-deletion strain compared to wild type, although the velocities of the movements were comparable. Co-localization of GFP-ChsB and GFP-CsmA with mRFP1-KinArigor, a KinA mutant that binds to microtubules but does not move along them, was observed in the posterior of the hyphal tip regions. KinA co-immunoprecipitated with ChsB and CsmA. Co-localization and association of CsmA with KinA did not depend on the MMD. These findings indicate that ChsB and CsmA are transported along microtubules to the subapical region by KinA. PMID:25955346

  2. Diabetes and the Mediterranean diet: a beneficial effect of oleic acid on insulin sensitivity, adipocyte glucose transport and endothelium-dependent vasoreactivity

    Microsoft Academic Search

    M. R YAN; D. M CINERNEY; D. OWENS; P. COLLINS; A. JOHNSON; G. H. T OMKIN

    2000-01-01

    Summary Abnormalities in endothelial function may be associ- transport was significantly greater on the oleic- ated with increased cardiovascular risk in diabetic acid-rich diet (0.56±0.17 vs. 0.29±0.14 nmol\\/105 patients. We examined the effect of an oleic-acid- cells\\/3 min, p<0.0001). Endothelium-dependent rich diet on insulin resistance and endothelium- flow-mediated vasodilatation (FMD) was signific- dependent vasoreactivity in type 2 diabetes. Eleven antly

  3. Polarimetric SAR data compensation for terrain azimuth slope variation

    Microsoft Academic Search

    Jong-Sen Lee; Dale L. Schuler; Thomas L. Ainsworth

    2000-01-01

    This paper addresses the problem of polarimetric SAR (POLSAR) data correction for changes in radar cross sections, which are caused by azimuth slopes. Most radiometric slope corrections remove slope effects to account for the effective scattering pixel area. However, few studies address the slope effect on the radar cross section as a function of polarization states. The authors propose two

  4. Vacuum Calculations in Azimuthally Symmetric Geometry \\Lambda M. S. Chance

    E-print Network

    Vacuum Calculations in Azimuthally Symmetric Geometry \\Lambda M. S. Chance Princeton University' is therefore built into the calculations for such assurances in the numerical accuracy. The code, `vacuum the volume integrated perturbed magnetic energy in the vacuum region or through the continuity requirements

  5. Vacuum Calculations in Azimuthally Symmetric Geometry M. S. Chance

    E-print Network

    Vacuum Calculations in Azimuthally Symmetric Geometry M. S. Chance Princeton University Plasma into the calculations for such assurances in the numerical accuracy. The code, `vacuum', described in the present work energy in the vacuum region or through the continuity requirements for the normal component

  6. Azimuthal Anisotropy In Radar Backscatter From The Ocean

    NASA Technical Reports Server (NTRS)

    Li, F. K.; Neumann, G.; Shaffer, S. J.; Durden, S. L.

    1991-01-01

    Minima offset from nominal crosswind directions. Report describes experimental and theoretical study of azimuthal anisotropy in radar backscatter from surface of ocean. Important objective of this and related studies to enhance ability to sense speed and direction of surface wind remotely by use of airborne or spaceborne radar.

  7. The Azimuth Project: an open-access educational resource

    E-print Network

    Baez, John

    reaction networks,... 3. A wiki for storing information, #12;Among other things, the Azimuth Project reaction networks,... 3. A wiki for storing information, a forum for talking to each other, #12;Among other: box models, chemical reaction networks,... 3. A wiki for storing information, a forum for talking

  8. Laser resonator supporting a nondiffracting, azimuthally polarized mode.

    PubMed

    Muys, Peter

    2012-07-01

    We analyze the lowest-order mode supported by a laser resonator containing an intra-cavity transmissive axicon using the Fox-Li iteration algorithm. Two configurations were considered. By proper choice of the cavity dimensions, the lowest-order mode is nondiffracting and azimuthally polarized. The mode pattern at the output coupler is a Bessel function of the first order. PMID:22743476

  9. Development of a Label-free Assay for Sodium-Dependent Phosphate Transporter NaPi-IIb

    Microsoft Academic Search

    Soo-Hang Wong; Alice Gao; Sabrina Ward; Charles Henley; Paul H. Lee

    2012-01-01

    The most widely used assay format for characterizing plasma membrane transporter activity measures accumulation of radiolabeled substrates in tissues or cells expressing the transporters. This assay format had limitations and disadvantages; therefore, there was an unmet need for development of a homogeneous, nonradioactive assay for membrane transporter proteins. In this report, the authors describe the development of a label-free homogeneous

  10. Acute increase, stimulated by prostaglandin E2, in glucose absorption via the sodium dependent glucose transporter-1 in rat intestine

    PubMed Central

    Scholtka, B; Stumpel, F; Jungermann, K

    1999-01-01

    BACKGROUND/AIMS—Acute stimulation by cAMP of the sodium dependent glucose cotransporter SGLT1 has previously been shown. As prostaglandin E2 (PGE2) increases intracellular cAMP concentrations via its receptor subtypes EP2R and EP4R, it was investigated whether PGE2 could enhance intestinal glucose absorption. ?METHODS—The action of PGE2 on carbohydrate absorption in the ex situ perfused rat small intestine and on 3-O-[14C]methylglucose uptake in isolated villus tip enterocytes was determined. Expression of mRNA for the PGE2 receptor subtypes 1-4 was assayed in enterocytes by reverse transcriptase polymerase chain reaction (RT-PCR). ?RESULTS—In the perfused small intestine, PGE2 acutely increased absorption of glucose and galactose, but not fructose (which is not a substrate for SGLT1); in isolated enterocytes it stimulated 3-O-[14C]methylglucose uptake. The 3-O-[14C]methylglucose uptake could be inhibited by the cAMP antagonist RpcAMPS and the specific inhibitor of SGLT1, phlorizin. High levels of EP2R mRNA and EP4R mRNA were detected in villus tip enterocytes. ?CONCLUSION—PGE2 acutely increased glucose and galactose absorption by the small intestine via the SGLT1, with cAMP serving as the second messenger. PGE2 acted directly on the enterocytes, as the stimulation was still observed in isolated enterocytes and RT-PCR detected mRNA for the cAMP-increasing PGE2 receptors EP2R and EP4R. ?? Keywords: glucose absorption; sodium dependent glucose transporter (SGLT1); prostaglandin; intestine; rat PMID:10075955

  11. Three-Dimensional Numerical Simulation of Density-Dependent Groundwater Flow and Salt Transport Due to Groundwater Pumping in an Unsaturated Fractured Porous Coastal Aquifer System

    Microsoft Academic Search

    J. Kihm; J. Kim

    2009-01-01

    A series of three-dimensional numerical simulations using a generalized multidimensional hydrodynamic dispersion numerical model is performed to analyze density-dependent groundwater flow and salt transport before and during groundwater pumping in an unsaturated fractured porous coastal aquifer system, which is heterogeneous and anisotropic. The coastal aquifer system is located on the western coast of Korea and is composed of the Quaternary

  12. Evidence that Akt mediates platelet-derived growth factor-dependent increases in activity and surface expression of the neuronal glutamate transporter, EAAC1.

    PubMed

    Krizman-Genda, Elizabeth; González, Marco I; Zelenaia, Olga; Robinson, Michael B

    2005-11-01

    Previously we have shown that platelet-derived growth factor (PDGF) rapidly increases the activity of the neuronal glutamate transporter, EAAC1. This increase in activity is associated with a rapid (within minutes) redistribution of transporter from a subcellular compartment to the plasma membrane and is blocked by inhibitors of phosphatidylinositol 3-kinase (PI3K). Similar effects of PI3K inhibitors have been observed for insulin-dependent up-regulation of the GLUT4 subtype of glucose transporter. Although GLUT4 regulation also depends on the serine-threonine kinase (Akt/protein kinase B), a downstream target of PI3K, the downstream effectors responsible of PDGF-dependent regulation of EAAC1 have not been identified. In the present study, PDGF increased the level of Akt phosphorylation (Ser 473) in C6 glioma cells, a cell line that has been used to study regulated trafficking of endogenous EAAC1. Two inhibitors of PI3K blocked this effect. In transient transfection studies, a dominant negative mutant of Akt-1 blocked PDGF-induced redistribution of epitope-tagged EAAC1 (myc-EAAC1). Conversely, constitutively active Akt-1 (CA Akt-1) increased the cell surface expression of myc-EAAC1. A lentiviral vector engineered to express CA Akt-1 increased Akt activation, cell surface expression of endogenous EAAC1, and Na(+)-dependent glutamate transport activity. Together, these studies suggest that Akt is required for PDGF-induced regulation of EAAC1. PMID:16182322

  13. Azimuthal Jet Tomography at RHIC and LHC

    E-print Network

    Barbara Betz; Miklos Gyulassy

    2014-07-28

    Results based on a generic jet-energy loss model that interpolates between running coupling pQCD-based and AdS/CFT-inspired holographic prescriptions are compared to recent data on the high-p_T pion nuclear modification factor and the high-p_T elliptic flow in nuclear collisions at RHIC and LHC. The jet-energy loss model is coupled to various (2+1)d (viscous hydrodynamic) fields. The impact of energy-loss fluctuations is discussed. While a previously proposed AdS/CFT jet-energy loss model with a temperature-independent jet-medium coupling is shown to be inconsistent with the LHC data, we find a rather broad class of jet-energy independent energy-loss models $dE/dx= \\kappa(T) x^z T^{2+z}$ that can account for the current data with different temperature-dependent jet-medium couplings $\\kappa(T)$ and path-length dependence exponents of $0\\le z \\le 2$.

  14. Electronic transport regimes through an alkoxythiolated diphenyl-2,2'-bithiophene-based molecular junction diodes: critical assessment of the thermal dependence

    NASA Astrophysics Data System (ADS)

    Pace, Giuseppina; Caranzi, Lorenzo; Bucella, Sadir G.; Canesi, Eleonora V.; Dell'Erba, Giorgio; Bertarelli, Chiara; Caironi, Mario

    2015-01-01

    The detailed understanding of electronic transport through a single molecule or an ensemble of self-assembled molecules embedded between two metallic leads is still a matter of controversy. Multiple factors influence the charge transport in the molecular junction, with particular attention to be given to the band states of the electrodes, molecular orbital energies, bias potential and importantly molecule-electrode electronic coupling. Moreover it is not trivial to disentangle molecular contributions from other possible conduction pathways directly coupling the opposite electrodes. We here investigate the electronic transport properties of an ensemble molecular junction embedding an alkylthiol derivative of a diphenol substituted bithiophene (DPBT) by means of current vs. voltage and temperature dependent measurements. We explored different junction configurations using: micropores (Au//DPBT//Au and Au//DPBT-polymer conductor//Au) and conductive-atomic force microscopy (c-AFM). In all cases, we found a transition voltage VT of ~0.35 V. The consistent presence of a similar VT in all the tested configurations is a strong, but not conclusive, indication of a molecular signature in the charge transport, which we assessed and confirmed by temperature dependent measurements. We found a transition from an incoherent resonant tunneling at low biases and close to room temperature, where transport is thermally activated with an activation energy of ~85 meV, to a coherent tunneling at voltages higher than VT. Unlike many other molecular junctions reported in the literature, resonant conditions commonly attributed to a hopping transport regime can be found already at room temperature and very low biases for a molecule only ~1.5 nm long. This paper is the first report to clearly show temperature activated transport through a short and not fully conjugated molecule. Moreover, we could clearly identify a regime at low temperatures and low bias where the transport mechanism is controlled by the thermal conductivity of the metal electrodes rather than the molecule.The detailed understanding of electronic transport through a single molecule or an ensemble of self-assembled molecules embedded between two metallic leads is still a matter of controversy. Multiple factors influence the charge transport in the molecular junction, with particular attention to be given to the band states of the electrodes, molecular orbital energies, bias potential and importantly molecule-electrode electronic coupling. Moreover it is not trivial to disentangle molecular contributions from other possible conduction pathways directly coupling the opposite electrodes. We here investigate the electronic transport properties of an ensemble molecular junction embedding an alkylthiol derivative of a diphenol substituted bithiophene (DPBT) by means of current vs. voltage and temperature dependent measurements. We explored different junction configurations using: micropores (Au//DPBT//Au and Au//DPBT-polymer conductor//Au) and conductive-atomic force microscopy (c-AFM). In all cases, we found a transition voltage VT of ~0.35 V. The consistent presence of a similar VT in all the tested configurations is a strong, but not conclusive, indication of a molecular signature in the charge transport, which we assessed and confirmed by temperature dependent measurements. We found a transition from an incoherent resonant tunneling at low biases and close to room temperature, where transport is thermally activated with an activation energy of ~85 meV, to a coherent tunneling at voltages higher than VT. Unlike many other molecular junctions reported in the literature, resonant conditions commonly attributed to a hopping transport regime can be found already at room temperature and very low biases for a molecule only ~1.5 nm long. This paper is the first report to clearly show temperature activated transport through a short and not fully conjugated molecule. Moreover, we could clearly identify a regime at low temperatures and low bias where the transport mechanism is controlled by th

  15. Mean zonal flow generated by azimuthal harmonic forcing in a rotating cylinder

    NASA Astrophysics Data System (ADS)

    Sauret, A.

    2015-06-01

    In this paper, we study analytically the flow in a rotating container subjected to an azimuthal forcing. We show that this mechanical forcing generates a correction to the solid body rotation called mean zonal flow, similar to the time oscillation of the rotation rate of an axisymmetric container. This axisymmetric correction induced by nonlinear effects in the Ekman layers modifies the solid-body rotation of the fluid in the container. At the leading order, the contribution in the bulk is shown to be an azimuthal flow which scales as the square of the amplitude of the multipolar deformation and is independent of the Ekman number. We also show that the mean zonal flow depends on the symmetry of the angular forcing n and the ratio of the angular rate of the deformation to the angular rate of the cylinder {{? }R}={{? }orb}/{{? }spin}. We found that for an elliptical forcing, n = 2, the rotation rate of the zonal flow does not depend on the radial position. In addition, the angular rate is found to be asymmetric with respect to {{? }R}. These scalings are similar to the time harmonic forcing in a cylinder. The particular case of a tidal forcing is also considered.

  16. Characterization of the 5' regulatory region of the human sodium-dependent multivitamin transporter, hSMVT.

    PubMed

    Dey, Sanjit; Subramanian, Veedamali S; Chatterjee, Nabendu S; Rubin, Stanley A; Said, Hamid M

    2002-03-19

    We cloned and functionally characterized the 5' regulatory region of the human sodium-dependent multivitamin transporter (hSMVT) gene, a remarkably versatile carrier responsible for uptake of biotin, pantothenic acid and lipoate. Two potential transcriptional start sites were determined by 5'-RACE and found to be at -4603, and -4303. Two distinct promoters (P1 and P2) were identified. Both putative promoter sequences were TATA-less, CAAT-less, contained highly GC-rich sites, and had multiple putative regulatory cis-elements (e.g., AP1, AP2, C/EBP, SP1, NF1, and GATA). The activities of the putative promoters were confirmed using a firefly luciferase reporter gene assay system following transient transfection into three cultured human cell lines: Caco-2, HEK293, and vascular smooth muscle cells. The minimal region required for basal activity of the hSMVT promoter was also determined by generating a series of deletion constructs and found to be encoded by a sequence between -5846 to -5313 for P1 and between -4417 to -4244 for P2 relative to the translation initiation codon. These results demonstrate the first molecular characterization of the regulatory region of this important human gene. PMID:11955628

  17. An iron-regulated and glycosylation-dependent proteasomal degradation pathway for the plasma membrane metal transporter ZIP14

    PubMed Central

    Zhao, Ningning; Zhang, An-Sheng; Worthen, Christal; Knutson, Mitchell D.; Enns, Caroline A.

    2014-01-01

    Protein degradation is instrumental in regulating cellular function. Plasma membrane proteins targeted for degradation are internalized and sorted to multivesicular bodies, which fuse with lysosomes, where they are degraded. ZIP14 is a newly identified iron transporter with multitransmembrane domains. In an attempt to dissect the molecular mechanisms by which iron regulates ZIP14 levels, we found that ZIP14 is endocytosed, extracted from membranes, deglycosylated, and degraded by proteasomes. This pathway did not depend on the retrograde trafficking to the endoplasmic reticulum and thus did not involve the well-defined endoplasmic reticulum-associated protein degradation pathway. Iron inhibited membrane extraction of internalized ZIP14, resulting in higher steady-state levels of ZIP14. Asparagine-linked (N-linked) glycosylation of ZIP14, particularly the glycosylation at N102, was required for efficient membrane extraction of ZIP14 and therefore is necessary for its iron sensitivity. These findings highlight the importance of proteasomes in the degradation of endocytosed plasma membrane proteins. PMID:24927598

  18. Energy Dependence of Directed Flow in Au+Au Collisions from a Multi-phase Transport Model

    E-print Network

    J. Y. Chen; J. X. Zuo; X. Z. Cai; F. Liu; Y. G. Ma; A. H. Tang

    2009-12-09

    The directed flow of charged hadron and identified particles has been studied in the framework of a multi-phase transport (AMPT) model, for $^{197}$Au+$^{197}$Au collisions at $\\sqrt{s_{NN}}=$200, 130, 62.4, 39, 17.2 and 9.2 GeV. The rapidity, centrality and energy dependence of directed flow for charged particles over a wide rapidity range are presented. AMPT model gives the correct $v_1(y)$ slope, as well as its trend as a function of energy, while it underestimates the magnitude. Within the AMPT model, the proton $v_1$ slope is found to change its sign when the energy increases to 130 GeV - a feature that is consistent with ``anti-flow''. Hadronic re-scattering is found having little effect on $v_1$ at top RHIC energies. These studies can help us to understand the collective dynamics at early times in relativistic heavy-ion collisions, and they can also be served as references for the RHIC Beam Energy Scan program.

  19. Dispersion of Anomalous Azimuthal Rotation and Circular Extinction Contrast in Dyed K2SO4 Crystals

    E-print Network

    Kaminsky, Werner

    Dispersion of Anomalous Azimuthal Rotation and Circular Extinction Contrast in Dyed K2SO4 Crystals Wiley-Liss, Inc. KEY WORDS: dyed crystals; K2SO4; Trypan blue; azimuthal rotation; circular extinction

  20. Electronic transport regimes through an alkoxythiolated diphenyl-2,2'-bithiophene-based molecular junction diodes: critical assessment of the thermal dependence.

    PubMed

    Pace, Giuseppina; Caranzi, Lorenzo; Bucella, Sadir G; Canesi, Eleonora V; Dell'Erba, Giorgio; Bertarelli, Chiara; Caironi, Mario

    2015-02-01

    The detailed understanding of electronic transport through a single molecule or an ensemble of self-assembled molecules embedded between two metallic leads is still a matter of controversy. Multiple factors influence the charge transport in the molecular junction, with particular attention to be given to the band states of the electrodes, molecular orbital energies, bias potential and importantly molecule-electrode electronic coupling. Moreover it is not trivial to disentangle molecular contributions from other possible conduction pathways directly coupling the opposite electrodes. We here investigate the electronic transport properties of an ensemble molecular junction embedding an alkylthiol derivative of a diphenol substituted bithiophene (DPBT) by means of current vs. voltage and temperature dependent measurements. We explored different junction configurations using: micropores (Au//DPBT//Au and Au//DPBT-polymer conductor//Au) and conductive-atomic force microscopy (c-AFM). In all cases, we found a transition voltage V(T) of ?0.35 V. The consistent presence of a similar V(T) in all the tested configurations is a strong, but not conclusive, indication of a molecular signature in the charge transport, which we assessed and confirmed by temperature dependent measurements. We found a transition from an incoherent resonant tunneling at low biases and close to room temperature, where transport is thermally activated with an activation energy of ?85 meV, to a coherent tunneling at voltages higher than V(T). Unlike many other molecular junctions reported in the literature, resonant conditions commonly attributed to a hopping transport regime can be found already at room temperature and very low biases for a molecule only ?1.5 nm long. This paper is the first report to clearly show temperature activated transport through a short and not fully conjugated molecule. Moreover, we could clearly identify a regime at low temperatures and low bias where the transport mechanism is controlled by the thermal conductivity of the metal electrodes rather than the molecule. PMID:25559138

  1. ATP-dependent binding cassette transporter G family member 16 increases plant tolerance to abscisic acid and assists in basal resistance against Pseudomonas syringae DC3000.

    PubMed

    Ji, Hao; Peng, Yanhui; Meckes, Nicole; Allen, Sara; Stewart, C Neal; Traw, M Brian

    2014-10-01

    Plants have been shown previously to perceive bacteria on the leaf surface and respond by closing their stomata. The virulent bacterial pathogen Pseudomonas syringae pv tomato DC3000 (PstDC3000) responds by secreting a virulence factor, coronatine, which blocks the functioning of guard cells and forces stomata to reopen. After it is inside the leaf, PstDC3000 has been shown to up-regulate abscisic acid (ABA) signaling and thereby suppress salicylic acid-dependent resistance. Some wild plants exhibit resistance to PstDC3000, but the mechanisms by which they achieve this resistance remain unknown. Here, we used genome-wide association mapping to identify an ATP-dependent binding cassette transporter gene (ATP-dependent binding cassette transporter G family member16) in Arabidopsis (Arabidopsis thaliana) that contributes to wild plant resistance to PstDC3000. Through microarray analysis and ?-glucuronidase reporter lines, we showed that the gene is up-regulated by ABA, bacterial infection, and coronatine. We also used a green fluorescent protein fusion protein and found that transporter is more likely to localize on plasma membranes than in cell walls. Transferred DNA insertion lines exhibited consistent defective tolerance of exogenous ABA and reduced resistance to infection by PstDC3000. Our conclusion is that ATP-dependent binding cassette transporter G family member16 is involved in ABA tolerance and contributes to plant resistance against PstDC3000. This is one of the first examples, to our knowledge, of ATP-dependent binding cassette transporter involvement in plant resistance to infection by a bacterial pathogen. It also suggests a possible mechanism by which plants reduce the deleterious effects of ABA hijacking during pathogen attack. Collectively, these results improve our understanding of basal resistance in Arabidopsis and offer unique ABA-related targets for improving the innate resistance of plants to bacterial infection. PMID:25146567

  2. Characterization of Organic Anion Transporter 2 (SLC22A7): A Highly Efficient Transporter for Creatinine and Species-Dependent Renal Tubular Expression.

    PubMed

    Shen, Hong; Liu, Tongtong; Morse, Bridget L; Zhao, Yue; Zhang, Yueping; Qiu, Xi; Chen, Cliff; Lewin, Anne C; Wang, Xi-Tao; Liu, Guowen; Christopher, Lisa J; Marathe, Punit; Lai, Yurong

    2015-07-01

    The contribution of organic anion transporter OAT2 (SLC22A7) to the renal tubular secretion of creatinine and its exact localization in the kidney are reportedly controversial. In the present investigation, the transport of creatinine was assessed in human embryonic kidney (HEK) cells that stably expressed human OAT2 (OAT2-HEK) and isolated human renal proximal tubule cells (HRPTCs). The tubular localization of OAT2 in human, monkey, and rat kidney was characterized. The overexpression of OAT2 significantly enhanced the uptake of creatinine in OAT2-HEK cells. Under physiologic conditions (creatinine concentrations of 41.2 and 123.5 µM), the initial rate of OAT2-mediated creatinine transport was approximately 11-, 80-, and 80-fold higher than OCT2, multidrug and toxin extrusion protein (MATE)1, and MATE2K, respectively, resulting in approximately 37-, 1850-, and 80-fold increase of the intrinsic transport clearance when normalized to the transporter protein concentrations. Creatinine intracellular uptake and transcellular transport in HRPTCs were decreased in the presence of 50 µM bromosulfophthalein and 100 µM indomethacin, which inhibited OAT2 more potently than other known creatinine transporters, OCT2 and multidrug and toxin extrusion proteins MATE1 and MATE2K (IC50: 1.3 µM vs. > 100 µM and 2.1 µM vs. > 200 µM for bromosulfophthalein and indomethacin, respectively) Immunohistochemistry analysis showed that OAT2 protein was localized to both basolateral and apical membranes of human and cynomolgus monkey renal proximal tubules, but appeared only on the apical membrane of rat proximal tubules. Collectively, the findings revealed the important role of OAT2 in renal secretion and possible reabsorption of creatinine and suggested a molecular basis for potential species difference in the transporter handling of creatinine. PMID:25904762

  3. Rayleigh Wave Azimuthal Anisotropy beneath the Hawaiian Swell - Evidence for plume-related mantle flow

    NASA Astrophysics Data System (ADS)

    Laske, Gabi; Marzen, Rachel

    2015-04-01

    During the two-stage Hawaiian PLUME (Plume-Lithosphere Undersea Melt Experiment) deployment, we collected continuous seismic data at ten land stations and nearly 70 ocean bottom sites from 2005 through mid-2007. Both the usage broad-band seismometers as well as the central location of Hawaii with good azimuthal seismicity coverage allows us to conduct a comprehensive analysis of surface wave azimuthal anisotropy at periods between 20 and 100 s. Using a triangle method that we developed for earlier studies, we fit propagating spherical wave fronts to the phases at three stations simultaneously to determine the frequency-dependent average phase velocity within these triangles. We use the standard Smith-and-Dahlen parameterization to express azimuthal variations. A systematic comparison between results obtained for different truncation levels in the trigonometric expansion allows us to assess stability of the results and assign error bars. We observe a marked shift in the overall geometry of fast directions. At periods shorter than about 30 s, the fast direction aligns coherently with the fossil spreading direction across the entire PLUME network. This result supports the idea that flow-aligned asthenospheric material is added to the cooling plate as it thickens. This is also consistent with published PLUME shear-wave splitting observations. However, at longer periods, that sense the asthenosphere below the fast direction rotates incoherently, indicating that flow in the asthenosphere is significantly perturbed from the direction of current plate motion. We present results from forward modeling as well as initial inversions that suggest that plume-related mantle flow does not reach into the upper lithosphere, at the scales imposed by both the PLUME station spacing and the surface waves used in this study.

  4. Development of Na/sup +/-dependent hexose transport in cultured renal epithelial cells (LLC-PK/sub 1/)

    SciTech Connect

    Weiss, E.R.; Amsler, K.; Dawson, W.D.; Cook, J.S.

    1984-01-01

    A number of factors were explored to analyze how they interact to yield the increasing transport capacity in differentiating cell populations. These factors include the number of functional transporters in the population, the distribution of these transporters among the individual cells, the Na/sup +/ chemical gradient, the transmembrane potential, the pathways and activities of these pathways for efflux of glucoside, and cell-cell coupling between accumulating and non-accumulating cells. 35 references, 9 figures, 2 tables. (ACR)

  5. Polarization dependent asymmetric magneto-resistance features in nanocrystalline diamond films

    SciTech Connect

    Bhattacharyya, Somnath, E-mail: Somnath.Bhattacharyya@wits.ac.za [Nano-Scale Transport Physics Laboratory, School of Physics, University of the Witwatersrand, Private Bag 3, WITS 2050, Johannesburg (South Africa); DST/NRF Centre of Excellence in Strong Materials, University of the Witwatersrand, Private Bag 3, WITS 2050, Johannesburg, South Africa and Department of Physics and Astronomy, University of Leeds, Leeds LS2 9JT (United Kingdom); Churochkin, Dmitry [Nano-Scale Transport Physics Laboratory, School of Physics, University of the Witwatersrand, Private Bag 3, WITS 2050, Johannesburg (South Africa)

    2014-08-18

    Polar angle-dependence of magneto-resistance (AMR) in heavily nitrogen-incorporated ultra-nanocrystalline diamond (UNCD) films is recorded by applying high magnetic fields, which shows strong anisotropic features at low temperatures. The temperature-dependence of MR and AMR can reveal transport in the weak-localization regime, which is explained by using a superlattice model for arbitrary values of disorder and angles. While a propagative Fermi surface model explains the negative MR features for low degree of disorder the azimuthal angle-dependent MR shows field dependent anisotropy due to the aligned conducting channels on the layers normal to film growth direction. The analysis of MR and AMR can extract the temperature dependence of dephasing time with respect to the elastic scattering time which not only establishes quasi-two dimensional features in this system but also suggests a potential application in monitoring the performance of UNCD based quantum devices.

  6. Blockade of glycine transporter 1 by SSR-504734 promotes cognitive flexibility in glycine/NMDA receptor-dependent manner.

    PubMed

    Nikiforuk, Agnieszka; Kos, Tomasz; Rafa, Dominik; Behl, Berthold; Bespalov, Anton; Popik, Piotr

    2011-01-01

    Accumulating evidence suggests that cognitive processes may be regulated by glycine concentration in the local environment of glutamate N-methyl-d-aspartate receptor (NMDAR). The concentration of glycine is controlled, among other factors, by the glycine transporter 1 (GlyT1). While GlyT1 inhibitors are developed for a number of indications including cognitive improvement, little is known about their effects in tasks depending on prefrontal cortical function. We examined the effect of GlyT1 inhibitor SSR-504734 on cognitive flexibility assessed in the attentional set-shifting task in rats (ASST). The second goal was to elucidate whether SSR-504734 effect has been due to the compound's action at glycine/NMDAR site. Rats treated with SSR-504734 (3 and 10 mg/kg, IP) required significantly less trials to criteria during extra-dimensional shift (EDs) phase of the ASST. The effect of SSR-504734 (3 mg/kg) was completely prevented by the glycine/NMDAR site antagonist, L-687,414 (30 mg/kg, IP) that by itself exerted no effect on cognitive flexibility. Present study demonstrates that the elevation of glycine concentration through the blockade of its reuptake facilitates cognitive flexibility. As this effect was fully blocked by glycine/NMDAR antagonist, SSR-504734-induced cognitive improvement is likely mediated through glycine action at NMDAR. It is suggested that GlyT1 inhibitors like SSR-504734 may represent a useful pharmacological approach for cognitive enhancement, especially in domains critically affected in schizophrenia. PMID:21530555

  7. Solid-state electron transport via cytochrome c depends on electronic coupling to electrodes and across the protein

    PubMed Central

    Amdursky, Nadav; Ferber, Doron; Bortolotti, Carlo Augusto; Dolgikh, Dmitry A.; Chertkova, Rita V.; Pecht, Israel; Sheves, Mordechai; Cahen, David

    2014-01-01

    Electronic coupling to electrodes, ?, as well as that across the examined molecules, H, is critical for solid-state electron transport (ETp) across proteins. Assessing the importance of each of these couplings helps to understand the mechanism of electron flow across molecules. We provide here experimental evidence for the importance of both couplings for solid-state ETp across the electron-mediating protein cytochrome c (CytC), measured in a monolayer configuration. Currents via CytC are temperature-independent between 30 and ?130 K, consistent with tunneling by superexchange, and thermally activated at higher temperatures, ascribed to steady-state hopping. Covalent protein–electrode binding significantly increases ?, as currents across CytC mutants, bound covalently to the electrode via a cysteine thiolate, are higher than those through electrostatically adsorbed CytC. Covalent binding also reduces the thermal activation energy, Ea, of the ETp by more than a factor of two. The importance of H was examined by using a series of seven CytC mutants with cysteine residues at different surface positions, yielding distinct electrode–protein(–heme) orientations and separation distances. We find that, in general, mutants with electrode-proximal heme have lower Ea values (from high-temperature data) and higher conductance at low temperatures (in the temperature-independent regime) than those with a distal heme. We conclude that ETp across these mutants depends on the distance between the heme group and the top or bottom electrode, rather than on the total separation distance between electrodes (protein width). PMID:24706771

  8. Directionality of nucleocytoplasmic transport of the retroviral gag protein depends on sequential binding of karyopherins and viral RNA

    PubMed Central

    Gudleski, Nicole; Flanagan, John M.; Bewley, Maria C.; Parent, Leslie J.

    2010-01-01

    Retroviral Gag polyproteins coopt host factors to traffic from cytosolic ribosomes to the plasma membrane, where virions are released. Before membrane transport, the multidomain Gag protein of Rous sarcoma virus (RSV) undergoes importin-mediated nuclear import and CRM1-dependent nuclear export, an intrinsic step in the assembly pathway. Transient nuclear trafficking of Gag is required for efficient viral RNA (vRNA) encapsidation, suggesting that Gag:vRNA binding might occur in the nucleus. Here, we show that Gag is imported into the nucleus through direct interactions of the Gag NC domain with importin-? (imp-?) and the MA domain with importin-11 (imp-11). The vRNA packaging signal, known as ?, inhibited imp-? binding to Gag, indicating that the NC domain does not bind to imp-? and vRNA simultaneously. Unexpectedly, vRNA binding also prevented the association of imp-11 with both the MA domain alone and with Gag, suggesting that the MA domain may bind to the vRNA genome. In contrast, direct binding of Gag to the nuclear export factor CRM1, via the CRM1-RanGTP heterodimer, was stimulated by ?RNA. These findings suggest a model whereby the genomic vRNA serves as a switch to regulate the ordered association of host import/export factors that mediate Gag nucleocytoplasmic trafficking for virion assembly. The Gag:vRNA interaction appears to serve multiple critical roles in assembly: specific selection of the vRNA genome for packaging, stimulating the formation of Gag dimers, and triggering export of viral ribonucleoprotein complexes from the nucleus. PMID:20435918

  9. Relative suppression of the sodium-dependent Vitamin C transport in mouse versus human lens epithelial cells.

    PubMed

    Obrenovich, Mark E; Fan, Xingjun; Satake, Makoto; Jarvis, Simon M; Reneker, Lixing; Reddan, John R; Monnier, Vincent M

    2006-12-01

    Vitamin C is a major antioxidant and UV absorbent in the human lens. In the rodent lens, the levels are very low for unknown reasons. Searching for clues to explain this suppression, we investigated the comparative uptake of Vitamin C in cultured human and mouse lens epithelial cells. When compared to human HLE-B3 lens epithelial cells, (14)C-ASA uptake was 4- to 10-fold impaired in confluent mouse lens 17EM15 (p < 0.0001) and 21EM15 (p < 0.001) cells, respectively. High glucose concentrations reduced the uptake by 30-50% in all cells (p < 0.005). Incubation of cells with 6-deoxy-6-fluoro-ascorbic (F-ASA), i.e. a probe specific for the sodium-dependent Vitamin C uptake (SVCT2), revealed a 10-fold uptake suppression into mouse 17EM15 relative to human HLE-B3 and JAR choriocarcinoma cells (a control), that could be overcome by overexpressing hSVCT2 using two different promoter constructs. The relative Vitamin C uptake differences suggest either low expression of SVCT2, molecular differences between the transporters themselves or their biological regulation, since a recent study has shown that exogenous feeding of ascorbic acid to rats increased only modestly lenticular uptake (Mody et al., Acta Ophthalmol Scand 83: 228-223, 2005). Elucidation of the mechanism by which SCVT2 activity is suppressed in mouse lens may help unravel a major question of evolutionary significance for night vision in nocturnal animals. PMID:16933033

  10. Rescue of dopamine transporter function in hypoinsulinemic rats by a D2 receptor-ERK dependent mechanism

    PubMed Central

    Owens, W. Anthony; Williams, Jason M.; Saunders, Christine; Avison, Malcolm J.; Galli, Aurelio; Daws, Lynette C.

    2012-01-01

    The dopamine (DA) transporter (DAT) is a major target for abused drugs and a key regulator of extracellular DA. A rapidly growing literature implicates insulin as an important regulator of DAT function. We previously showed that amphetamine (AMPH)-evoked DA release is markedly impaired in rats depleted of insulin with the diabetogenic agent, streptozotocin (STZ). Similarly, functional magnetic resonance imaging experiments revealed that the blood oxygenation level dependent (BOLD) signal following acute AMPH administration in STZ-treated rats is reduced. Here, we report that these deficits are restored by repeated, systemic administration of AMPH (1.78 mg/kg, every other day for 8 days). AMPH stimulates DA D2 receptors indirectly by increasing extracellular DA. Supporting a role for D2 receptors in mediating this “rescue”, the effect was completely blocked by pre-treatment of STZ-treated rats with the D2 receptor antagonist, raclopride, prior to systemic AMPH. D2 receptors regulate DAT cell surface expression through ERK1/2 signaling. In ex vivo striatal preparations, repeated AMPH injections increased immunoreactivity of phosphorylated ERK1/2 in STZ-treated, but not in control rats. These data suggest that repeated exposure to AMPH can rescue, by activating D2 receptors and p-ERK signaling, deficits in DAT function that result from hypoinsulinemia. Our data confirm the idea that disorders influencing insulin levels and/or signaling, such as diabetes and anorexia, can degrade DAT function and that insulin-independent pathways are present that may be exploited as potential therapeutic targets to restore normal DAT function. PMID:22357848

  11. Azimuthal modulation of cosmic ray flux as an effect of geomagnetic field in the ARGO-YBJ experiment

    E-print Network

    Bernardini, P; He, H H; Mancarella, G; Perrone, L; Surdo, A

    2011-01-01

    The geomagnetic field causes not only the East-West effect on the primary cosmic rays but also affects the trajectories of the secondary charged particles in the shower, causing their lateral distribution to be stretched along certain directions. Thus both the density of the secondaries near the shower axis and the trigger efficiency of a detector array decrease. The effect depends on the age and on the direction of the showers, thus involving the measured azimuthal distribution. Here the non-uniformity of the azimuthal distribution of the reconstructed events in the ARGO-YBJ experiment is deeply investigated for different zenith angles on the light of this effect. The influence of the geomagnetic field as well as geometric effects are studied by means of a Monte Carlo simulation.

  12. Pulse Azimuth Clusters Preceding Earthquakes in California, 2005-2010

    NASA Astrophysics Data System (ADS)

    Dunson, C.; Bleier, T. E.

    2010-12-01

    Increases in geomagnetic pulsation activity have been observed preceding many earthquakes in the Quakefinder magnetometer network. Some of these pulses are extremely large, and many have been shown to have consistent angle-of-arrival (azimuth), using the pairs of horizontal coils (North-South and East-West) found at each site. These pulsations can be seen 1-15 days prior to earthquakes nearby the same sites, and since they occur in bursts, they have been termed 'pulse azimuth clusters.' These clusters can be empirically studied using Bernoulli trials, and this approach can produce a favorable decision-making concept for an operational earthquake warning system. A number of issues regarding these ideas are elucidated for purposes of discussion by this poster.

  13. Experimental observation of azimuthal shock waves on nonlinear acoustical vortices

    NASA Astrophysics Data System (ADS)

    Brunet, Thomas; Thomas, Jean-Louis; Marchiano, Régis; Coulouvrat, François

    2009-01-01

    Thanks to a new focused array of piezoelectric transducers, experimental results are reported here to evidence helical acoustical shock waves resulting from the nonlinear propagation of acoustical vortices (AVs). These shock waves have a three-dimensional spiral shape, from which both the longitudinal and azimuthal components are studied. The inverse filter technique used to synthesize AVs allows various parameters to be varied, especially the topological charge which is the key parameter describing screw dislocations. Firstly, an analysis of the longitudinal modes in the frequency domain reveals a wide cascade of harmonics (up to the 60th order) leading to the formation of the shock waves. Then, an original measurement in the transverse plane exhibits azimuthal behaviour which has never been observed until now for acoustical shock waves. Finally, these new experimental results suggest interesting potential applications of nonlinear effects in terms of acoustics spanners in order to manipulate small objects.

  14. Uniaxial Cyclic Stretch-Stimulated Glucose Transport Is Mediated by a Ca2+Dependent Mechanism in Cultured Skeletal Muscle Cells

    Microsoft Academic Search

    Masahiro Iwata; Kimihide Hayakawa; Taro Murakami; Keiji Naruse; Keisuke Kawakami; Masumi Inoue-Miyazu; Louis Yuge; Shigeyuki Suzuki

    2007-01-01

    Objective: Mechanical stimuli such as stretch increase glucose transport and glycogen metabolism in skeletal muscle. However, the molecular mechanisms involved in the mechanotransduction events are poorly understood. The present study was conducted in order to determine whether the signaling mechanism leading to mechanical stretch-stimulated glucose transport is similar to, or distinct from, the signaling mechanisms leading to insulin- and contraction-stimulated

  15. The Arabidopsis GNOM ARF-GEF Mediates Endosomal Recycling, Auxin Transport, and Auxin-Dependent Plant Growth

    Microsoft Academic Search

    Niko Geldner; Nadine Anders; Hanno Wolters; Jutta Keicher; Wolfgang Kornberger; Philippe Muller; Alain Delbarre; Takashi Ueda; Akihiko Nakano; Gerd Jurgens

    2003-01-01

    hormone auxin. Mutations in GNOM lead to develop- tion mutants displaying striking embryonic phenotypes mental defects that resemble those caused by interfer- (Mayer et al., 1993). Mutant embryos show a loss of ing with auxin transport. Both PIN1 localization and cell-to-cell alignment along the embryonic axis, lack the auxin transport are also sensitive to BFA. In this paper, embryonic root,

  16. Analytical solutions of the one-dimensional advection-dispersion solute transport equation subject to time-dependent boundary conditions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Analytical solutions of the advection-dispersion solute transport equation remain useful for a large number of applications in science and engineering. In this paper we extend the Duhamel theorem, originally established for diffusion type problems, to the case of advective-dispersive transport subj...

  17. Unpolarized Azimuthal Asymmetries from the COMPASS Experiment at CERN

    SciTech Connect

    Joosten, Rainer [HISKP, University Bonn, Nussallee 14-16, 53115 Bonn (Germany)

    2009-12-17

    Azimuthal asymmetries in unpolarized SIDIS can be used to probe the transverse momentum of the quarks inside the nucleon. Furthermore, they give access to the so-far unmeasured Boer-Mulders function. In this contribution, results on these asymmetries, extracted separately for positive and negative hadrons, from the COMPASS data taken with a 160 GeV/c {mu}{sup +} beam on a deuteron target will be reported and compared to theoretical predictions.

  18. Azimuthal asymmetries in SIDIS off unpolarized targets at COMPASS

    E-print Network

    Andrea Bressan; for the COMPASS Collaboration

    2009-07-31

    Azimuthal asymmetries measured in unpolarized semi-inclusive deep inelastic scattering bring important information on the inner structure of the nucleons, and can be used both to estimate the average quark transverse momentum k_T and to access the so-far unmeasured Boer-Mulders functions. COMPASS results using part of the 2004 data collected with a 6LiD target and a 160 GeV positive muon beam are presented separately for positive and negative hadrons.

  19. Dihadron Azimuthal Correlation from Collins Effect in Unpolarized Hadron Collisions

    SciTech Connect

    Yuan, Feng

    2010-01-05

    We study the dihadron azimuthal correlation produced nearly back-to-back in unpolarized hadron collisions, arising from the product of two Collins fragmentation functions. Using the latest Collins fragmentation functions extracted from the global analysis of available experimental data, we make predictions for the azimuthalcorrelation of two-pion production in pp collisions at RHIC energies. We find that the correlation is sizable in the mid-rapidity region for moderate jet transverse momentum.

  20. Azimuthal structures of produced particles in heavy-ion interactions

    SciTech Connect

    Vokal, S., E-mail: vokal@sunhe.jinr.ru; Orlova, G. I. [VBLHEP, JINR (Russian Federation); Lehocka, S. [University of P. J. Safarik (Slovakia)

    2009-02-15

    The angular structures of particles produced in {sup 208}Pb at 158 A GeV/c and {sup 197}Au at 11.6 A GeV/c induced interactions with Ag(Br) nuclei in emulsion detector have been investigated. Nonstatistical well-ordered ring-like structures of produced particles in azimuthal plane of a collision have been found, and their parameters have been determined.

  1. Propagation along azimuthally magnetized ferrite-loaded circular waveguides

    NASA Technical Reports Server (NTRS)

    Mueller, R. S.; Rosenbaum, F. J.

    1977-01-01

    The paper describes the modal dispersion characteristics of electromagnetic waves traveling along the azimuthally magnetized ferrite-loaded coaxial transmission line and the ferrite-loaded wire. The modal dispersion curves are used to determine the pass and stop bands of normal propagation. Boundary-value problems were solved with Bolle-Heller functions. The dispersion characteristics of transverse electric modes are presented as plots of the normalized propagation constant vs the normalized frequency.

  2. Multi-azimuthal-angle effects in self-induced supernova neutrino flavor conversions without axial symmetry

    NASA Astrophysics Data System (ADS)

    Mirizzi, Alessandro

    2013-10-01

    The flavor evolution of neutrinos emitted by a supernova (SN) core is strongly affected by the refractive effects associated with the neutrino-neutrino interactions in the deepest stellar regions. Till now, all numerical studies have assumed the axial symmetry for the “multi-angle effects” associated with the neutrino-neutrino interactions. Recently, it has been pointed out in Raffelt, Sarikas, and Seixas [Phys. Rev. Lett. 111, 091101 (2013)] that if this assumption is removed, a new multi-azimuthal-angle (MAA) instability emerges in the flavor evolution of the dense SN neutrino gas, in addition to the one caused by multi-zenith-angle effects. Inspired by this result, for the first time we numerically solve the nonlinear neutrino propagation equations in SN, introducing the azimuthal angle as an angular variable in addition to the usual zenith angle. We consider simple energy spectra with an excess of ?e over ?¯e. We find that even starting with a complete axial symmetric neutrino emission, the MAA effects would lead to significant flavor conversions in normal mass hierarchy, in cases otherwise stable under the only multi-zenith-angle effects. The final outcome of the flavor conversions, triggered by the MAA instability, depends on the initial asymmetry between ?e and ?¯e spectra. If it is sufficiently large, final spectra would show an ordered behavior with spectral swaps and splits. Conversely, for small flavor asymmetries flavor decoherence among angular modes develops, also affecting the flavor evolution in the inverted mass hierarchy.

  3. Measurement of azimuthal asymmetries in neutral current deep inelastic scattering at HERA

    NASA Astrophysics Data System (ADS)

    Chekanov, S.; Derrick, M.; Magill, S.; Miglioranzi, S.; Musgrave, B.; Nicholass, D.; Repond, J.; Yoshida, R.; Mattingly, M. C. K.; Pavel, N.; Yagües Molina, A. G.; Antonelli, S.; Antonioli, P.; Bari, G.; Basile, M.; Bellagamba, L.; Bindi, M.; Boscherini, D.; Bruni, A.; Bruni, G.; Cifarelli, L.; Cindolo, F.; Contin, A.; Corradi, M.; de Pasquale, S.; Iacobucci, G.; Margotti, A.; Nania, R.; Polini, A.; Rinaldi, L.; Sartorelli, G.; Zichichi, A.; Aghuzumtsyan, G.; Bartsch, D.; Brock, I.; Goers, S.; Hartmann, H.; Hilger, E.; Jakob, H.-P.; Jüngst, M.; Kind, O. M.; Paul, E.; Rautenberg, J.; Renner, R.; Samson, U.; Schönberg, V.; Wang, M.; Wlasenko, M.; Brook, N. H.; Heath, G. P.; Morris, J. D.; Namsoo, T.; Capua, M.; Fazio, S.; Mastroberardino, A.; Schioppa, M.; Susinno, G.; Tassi, E.; Kim, J. Y.; Ma, K. J.; Ibrahim, Z. A.; Kamaluddin, B.; Wan Abdullah, W. A. T.; Ning, Y.; Ren, Z.; Sciulli, F.; Chwastowski, J.; Eskreys, A.; Figiel, J.; Galas, A.; Gil, M.; Olkiewicz, K.; Stopa, P.; Zawiejski, L.; Adamczyk, L.; Bo?d, T.; Grabowska-Bo?d, I.; Kisielewska, D.; ?ukasik, J.; Przybycie?, M.; Suszycki, L.; Kota?ski, A.; S?omi?ski, W.; Adler, V.; Behrens, U.; Bloch, I.; Bonato, A.; Borras, K.; Coppola, N.; Fourletova, J.; Geiser, A.; Gladkov, D.; Göttlicher, P.; Gregor, I.; Gutsche, O.; Haas, T.; Hain, W.; Horn, C.; Kahle, B.; Kötz, U.; Kowalski, H.; Lim, H.; Lobodzinska, E.; Löhr, B.; Mankel, R.; Melzer-Pellmann, I.-A.; Montanari, A.; Nguyen, C. N.; Notz, D.; Nuncio-Quiroz, A. E.; Santamarta, R.; Schneekloth, U.; Spiridonov, A.; Stadie, H.; Stösslein, U.; Szuba, D.; Szuba, J.; Theedt, T.; Watt, G.; Wolf, G.; Wrona, K.; Youngman, C.; Zeuner, W.; Schlenstedt, S.; Barbagli, G.; Gallo, E.; Pelfer, P. G.; Bamberger, A.; Dobur, D.; Karstens, F.; Vlasov, N. N.; Bussey, P. J.; Doyle, A. T.; Dunne, W.; Ferrando, J.; Saxon, D. H.; Skillicorn, I. O.; Gialas, I.; Gosau, T.; Holm, U.; Klanner, R.; Lohrmann, E.; Salehi, H.; Schleper, P.; Schörner-Sadenius, T.; Sztuk, J.; Wichmann, K.; Wick, K.; Foudas, C.; Fry, C.; Long, K. R.; Tapper, A. D.; Kataoka, M.; Matsumoto, T.; Nagano, K.; Tokushuku, K.; Yamada, S.; Yamazaki, Y.; Barakbaev, A. N.; Boos, E. G.; Dossanov, A.; Pokrovskiy, N. S.; Zhautykov, B. O.; Son, D.; de Favereau, J.; Piotrzkowski, K.; Barreiro, F.; Glasman, C.; Jimenez, M.; Labarga, L.; Del Peso, J.; Ron, E.; Terrón, J.; Zambrana, M.; Corriveau, F.; Liu, C.; Walsh, R.; Zhou, C.; Tsurugai, T.; Antonov, A.; Dolgoshein, B. A.; Rubinsky, I.; Sosnovtsev, V.; Stifutkin, A.; Suchkov, S.; Dementiev, R. K.; Ermolov, P. F.; Gladilin, L. K.; Katkov, I. I.; Khein, L. A.; Korzhavina, I. A.; Kuzmin, V. A.; Levchenko, B. B.; Lukina, O. Y.; Proskuryakov, A. S.; Shcheglova, L. M.; Zotkin, D. S.; Zotkin, S. A.; Abt, I.; Büttner, C.; Caldwell, A.; Kollar, D.; Schmidke, W. B.; Sutiak, J.; Grigorescu, G.; Keramidas, A.; Koffeman, E.; Kooijman, P.; Pellegrino, A.; Tiecke, H.; Vázquez, M.; Wiggers, L.; Brümmer, N.; Bylsma, B.; Durkin, L. S.; Lee, A.; Ling, T. Y.; Allfrey, P. D.; Bell, M. A.; Cooper-Sarkar, A. M.; Cottrell, A.; Devenish, R. C. E.; Foster, B.; Gwenlan, C.; Korcsak-Gorzo, K.; Patel, S.; Roberfroid, V.; Robertson, A.; Straub, P. B.; Uribe-Estrada, C.; Walczak, R.; Bellan, P.; Bertolin, A.; Brugnera, R.; Carlin, R.; Ciesielski, R.; Dal Corso, F.; Dusini, S.; Garfagnini, A.; Limentani, S.; Longhin, A.; Stanco, L.; Turcato, M.; Oh, B. Y.; Raval, A.; Ukleja, J.; Whitmore, J. J.; Iga, Y.; D'Agostini, G.; Marini, G.; Nigro, A.; Cole, J. E.; Hart, J. C.; Abramowicz, H.; Gabareen, A.; Ingbir, R.; Kananov, S.; Levy, A.; Kuze, M.; Hori, R.; Kagawa, S.; Shimizu, S.; Tawara, T.; Hamatsu, R.; Kaji, H.; Kitamura, S.; Ota, O.; Ri, Y. D.; Ferrero, M. I.; Monaco, V.; Sacchi, R.; Solano, A.; Arneodo, M.; Ruspa, M.; Fourletov, S.; Martin, J. F.; Boutle, S. K.; Butterworth, J. M.; Hall-Wilton, R.; Jones, T. W.; Loizides, J. H.; Sutton, M. R.; Targett-Adams, C.; Wing, M.; Brzozowska, B.; Ciborowski, J.; Grzelak, G.; Kulinski, P.; ?u?niak, P.; Malka, J.; Nowak, R. J.; Pawlak, J. M.; Tymieniecka, T.; Ukleja, A.; ?arnecki, A. F.; Adamus, M.; Plucinski, P.; Eisenberg, Y.; Giller, I.; Hochman, D.; Karshon, U.; Rosin, M.; Brownson, E.; Danielson, T.; Everett, A.; Kcira, D.; Reeder, D. D.; Ryan, P.; Savin, A. A.; Smith, W. H.; Wolfe, H.; Bhadra, S.; Catterall, C. D.; Cui, Y.; Hartner, G.; Menary, S.; Noor, U.; Soares, M.; Standage, J.; Whyte, J.

    2007-07-01

    The distribution of the azimuthal angle of charged and neutral hadrons relative to the lepton plane has been studied for neutral current deep inelastic ep scattering using an integrated luminosity of 45 pb-1 taken with the ZEUS detector. The kinematic range is 100dependence of the moments of the azimuthal distributions on the pseudorapidity and minimum transverse energy of the final-state hadrons are presented. Although the predictions from next-to-leading-order QCD describe the data better than do the Monte Carlo models incorporating leading-logarithm parton showers, they still fail to describe the magnitude of the asymmetries. This suggests that higher-order calculations may be necessary to describe these data.

  4. Azimuthal convective rolls and the subsurface magnetic field

    NASA Astrophysics Data System (ADS)

    Merryfield, William J.

    1990-07-01

    The continual emergence of magnetic flux in solar active regions suggests that a substantial reservoir of flux is present somewhere beneath the photosphere. It has been proposed that this flux could be stored in an azimuthal field of order 3000 G residing in the lower portion of the convection zone. Such a field may be large enough to substantially influence the dynamics of the convection: linear stability analyses indicate that donut-like convective rolls having azimuthal symmetry might then be preferred to banana cells aligned with the rotation axis. Observational detections of such azimuthal rolls have been claimed. The problem of pattern selection by convection in the presence of rotation and a horizontal magnetic field is examined here in a model system consisting of a planar Boussinesq fluid layer. Nonlinear solutions are obtained numerically. It is found that solutions consisting solely of donut cells can exist even at parameter values at which linear theory suggests that banana cells should be preferred instead. However, when the horizontal field decays below a critical value, banana cells may then grow. This leads to the destruction of the horizontal field and a permanent transition to banana cells.

  5. Time-variable transit time distributions and transport: Theory and application to storage-dependent transport of chloride in a watershed

    NASA Astrophysics Data System (ADS)

    Harman, Ciaran J.

    2015-01-01

    Transport processes and pathways through many hydrodynamic systems vary over time, often driven by variations in total water storage. This paper develops a very general approach to modeling unsteady transport through an arbitrary control volume (such as a watershed) that accounts for temporal variability in the underlying transport dynamics. Controls on the selection of discharge from stored water are encapsulated in probability distributions ?Q>(ST,t>) of age-ranked storage ST (the volume of water in storage ranked from youngest to oldest). This framework is applied to a long-term record of rainfall and streamflow chloride in a small, humid watershed at Plynlimon, UK. While a time-invariant gamma distribution for ?Q produced a good fit to data, the fit was significantly improved when the distribution was allowed to vary with catchment storage. However, the variation was inverse to that of a "well-mixed" system where storage has a pure dilution effect. Discharge at high storage was predicted to contain a larger fraction of recent event water than at low storage. The effective volume of storage involved in transport was 3411 mm at mean catchment wetness, but declined by 71 mm per 1 mm of additional catchment storage, while the fraction of event water in discharge increased by 1.4%. This "inverse storage effect" is sufficient to reproduce the observed long-memory 1/f fractal spectral structure of stream chloride. Metrics quantifying the strength and direction of storage effects are proposed as useful signatures, and point toward a unified framework for observing and modeling coupled watershed flow and transport.

  6. P-glycoproteins and other multidrug resistance transporters in the pharmacology of anthelmintics: Prospects for reversing transport-dependent anthelmintic resistance

    PubMed Central

    Lespine, Anne; Ménez, Cécile; Bourguinat, Catherine; Prichard, Roger K.

    2011-01-01

    Parasitic helminths cause significant disease in animals and humans. In the absence of alternative treatments, anthelmintics remain the principal agents for their control. Resistance extends to the most important class of anthelmintics, the macrocyclic lactone endectocides (MLs), such as ivermectin, and presents serious problems for the livestock industries and threatens to severely limit current parasite control strategies in humans. Understanding drug resistance is important for optimizing and monitoring control, and reducing further selection for resistance. Multidrug resistance (MDR) ABC transporters have been implicated in ML resistance and contribute to resistance to a number of other anthelmintics. MDR transporters, such as P-glycoproteins, are essential for many cellular processes that require the transport of substrates across cell membranes. Being overexpressed in response to chemotherapy in tumour cells and to ML-based treatment in nematodes, they lead to therapy failure by decreasing drug concentration at the target. Several anthelmintics are inhibitors of these efflux pumps and appropriate combinations can result in higher treatment efficacy against parasites and reversal of resistance. However, this needs to be balanced against possible increased toxicity to the host, or the components of the combination selecting on the same genes involved in the resistance. Increased efficacy could result from modifying anthelmintic pharmacokinetics in the host or by blocking parasite transporters involved in resistance. Combination of anthelmintics can be beneficial for delaying selection for resistance. However, it should be based on knowledge of resistance mechanisms and not simply on mode of action classes, and is best started before resistance has been selected to any member of the combination. Increasing knowledge of the MDR transporters involved in anthelmintic resistance in helminths will play an important role in allowing for the identification of markers to monitor the spread of resistance and to evaluate new tools and management practices aimed at delaying its spread. PMID:24533264

  7. Azimuthal anisotropy layering and plate motion in the Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Yuan, H.; Romanowicz, B. A.

    2012-12-01

    We recently developed a three dimensional radially and azimuthally anisotropic model of the upper mantle in north America, using a combination of long-period 3-component surface and overtone waveforms, and SKS splitting measurements (Yuan and Romanowicz, 2010, Yuan et al., 2011). We showed that azimuthal anisotropy is a powerful tool to detect layering in the upper mantle, revealing two domains in the cratonic lithosphere, separated by a sharp laterally varying boundary in the depth range 100-150 km, which seems to coincide with the mid-lithospheric boundary (MLD) found in receiver function studies. Contrary to receiver functions, azimuthal anisotropy also detects the lithosphere-asthenosphere boundary (LAB) as manifested by a change in the fast axis direction, which becomes quasi-parallel to the absolute plate motion below ~250 km depth. A zone of stronger azimuthal anisotropy is found below the LAB both in the western US (peaking at depths of 100-150km) and in the craton (peaking at a depth of about 300 km). Here we show preliminary attempts at expanding our approach to the global scale, with a specific goal of determining whether such an anisotropic LAB can also be observed in the Pacific ocean. We started with our most recent global upper mantle radially anisotropic shear velocity model, determined using the Spectral Element Method (SEMum2; French et al., this meeting). We augment the corresponding global surface wave and overtone dataset (period range 60 to 400 s) with deep events and shorter period body waves, in order to ensure optimal deeper depth (>250km) anisotropy recovery due to the paucity of shear wave splitting measurements in the oceans. Our preliminary results, which do not yet incorporate SKS splitting measurements, look promising as they confirm the layering found previously in North America, using a different, global dataset and starting model. In the Pacific, our study confirms earlier azimuthal anisotropy results in the region (e.g. Smith et al. 2004; Maggi et al. 2006) that the shallow upper mantle beneath the ocean basin is strongly stratified. Our results further illustrate that 1) a shallow anisotropy domain (~100 km) is present, which is high in velocity and has in general a northward anisotropy direction where the plate is old (>80 Ma); and 2) there is a deeper domain (100-200 km) with stronger anisotropy, which correlates spatially with the low velocity zone and has a fast axis direction in good agreement with the absolute plate motion direction (HS3 NUVEL-1A). The boundary between the anisotropy domains clearly follows the age progressive deepening of the fast velocity in the shallow domain, suggesting an oceanic LAB that separates the Pacific lithosphere and the underlying asthenosphere.

  8. Flexible coupling between light-dependent electron and vectorial proton transport in illuminated leaves of C 3 plants. Role of photosystem I-dependent proton pumping

    Microsoft Academic Search

    Gabriel Cornic; Nicolai G. Bukhov; Christian Wiese; Richard Bligny; Ulrich Heber

    2000-01-01

    .   The role of cyclic electron transport has been re-examined in leaves of C3 plants because the bioenergetics of chloroplasts (H+\\/e?=?3 in the presence of a Q-cycle; H+\\/ATP?=?4 of ATP synthesis) had suggested that cyclic electron flow has no function in C3 photosynthesis. After light activation of pea leaves, the dark reduction of P700 (the donor pigment of PSI) following

  9. Comment on ’’Simulation of high-field transport in GaAs using a Monte Carlo method and pseudopotential band structures’’ and on ’’Band-structure dependent transport and impact ionization in GaAs’’

    Microsoft Academic Search

    F. Capasso; T. P. Pearsall; K. K. Thornber; R. E. Nahory; M. A. Pollack; G. B. Bachelet; J. R. Chelikowsky

    1982-01-01

    Recent theoretical work by Shichijo, Hess, and Stillman on a Monte Carlo simulation of high-field transport and impact ionization in GaAs is examined. The failure of that calculation to reproduce the experimentally well-documented orientation dependence of impact ionization can be directly related to the use of a phonon scattering rate that is unrealistically high. It is shown that such high

  10. Thiol-Dependent passive K\\/Cl transport in sheep red cells: IV. Furosemide inhibition as a function of external Rb + , Na + , and Cl ?

    Microsoft Academic Search

    P. K. Lauf

    1984-01-01

    Summary The effect of the loop diuretic furosemide (4-chloro-N-furfuryl-5-sulfamoyl-anthranilic acid) on the thiol-dependent, ouabain-insensitive K(Rb)\\/Cl transport in low K+ sheep red cells was studied at various concentrations of extracellular Rb+, Na+ and Cl-. In Rb+-free NaCl media, 2×10-3m furosemide inhibited only one-half of thiol-dependent K+ efflux. In the presence of 23mm RbCl, however, the concentration of furosemide to produce 50%

  11. Alignment dependence of one-dimensional electronic hopping transport observed in films of highly aligned, ultralong single-walled carbon nanotubes

    Microsoft Academic Search

    Cary L. Pint; Ya-Qiong Xu; Emilia Morosan; Robert H. Hauge

    2009-01-01

    The temperature dependent electrical conductivity of highly aligned, as-grown, pristine films of ultralong single-walled carbon nanotubes (SWNTs) is investigated in the framework of conduction based on phonon-assisted electron hopping. A change in transport mechanism occurs between conduction normal to and parallel to the SWNT alignment that results in evolution from bulk three-dimensional (3D) hopping conduction to a one-dimensional (1D) hopping

  12. Exploration of O-spiroketal C-arylglucosides as novel and selective renal sodium-dependent glucose co-transporter 2 (SGLT2) inhibitors

    Microsoft Academic Search

    Binhua Lv; Baihua Xu; Yan Feng; Kun Peng; Ge Xu; Jiyan Du; Lili Zhang; Wenbin Zhang; Ting Zhang; Liangcheng Zhu; Haifeng Ding; Zelin Sheng; Ajith Welihinda; Brian Seed; Yuanwei Chen

    2009-01-01

    A series of novel O-spiroketal C-arylglucosides have been prepared and evaluated in cell-based functional assays for activity against human sodium-dependent glucose co-transporters 1 and 2 (SGLT1 and 2). The core spiro[isobenzofuran-1,2?-pyran] structure proved to be an effective scaffold for diversification and a number of compounds with single digit nanomolar potency and high selectivity have been synthesized. Compound 5a promoted glucosuria

  13. Drastic Magnetoresistance Enhancement on Spin-Dependent-Transport and Appearance of Spin-Glass-Like Behavior for Magnetite Nanoparticle Sinter Calcined at Low Temperature

    Microsoft Academic Search

    H. Kobori; K. Ohnishi; A. Sugimura; T. Taniguchi

    2007-01-01

    We have studied the spin-dependent-transport and magnetization for magnetite nanoparticle sinter (MNPS) calcined at low temperature. As compared with a bulk crystal, the drastic enhancement of negative differential magnetoresistance has been obtained for the MNPS. Below the Verwey transition temperature, we have observed the difference of magnetization between zero-field-cooling and field-cooling. This phenomenon indicates that localized spins in amorphous-like grain-boundary

  14. Drastic Magnetoresistance Enhancement on Spin-Dependent-Transport and Appearance of Spin-Glass-Like Behavior for Magnetite Nanoparticle Sinter Calcined at Low Temperature

    NASA Astrophysics Data System (ADS)

    Kobori, H.; Ohnishi, K.; Sugimura, A.; Taniguchi, T.

    2007-04-01

    We have studied the spin-dependent-transport and magnetization for magnetite nanoparticle sinter (MNPS) calcined at low temperature. As compared with a bulk crystal, the drastic enhancement of negative differential magnetoresistance has been obtained for the MNPS. Below the Verwey transition temperature, we have observed the difference of magnetization between zero-field-cooling and field-cooling. This phenomenon indicates that localized spins in amorphous-like grain-boundary region in the MNPS are spin-glass-like.

  15. Long-range transport of black carbon to the Pacific Ocean and its dependence on aging timescale

    NASA Astrophysics Data System (ADS)

    Zhang, J.; Liu, J.; Tao, S.; Ban-Weiss, G. A.

    2015-06-01

    Improving the ability of global models to predict concentrations of black carbon (BC) over the Pacific Ocean is essential to evaluate the impact of BC on marine climate. In this study, we tag BC tracers from 13 source regions around the globe in a global chemical transport model MOZART-4. Numerous sensitivity simulations are carried out varying the aging timescale of BC emitted from each source region. The aging timescale for each source region is optimized by minimizing errors in vertical profiles of BC mass mixing ratios between simulations and HIAPER Pole-to-Pole Observations (HIPPO). For most HIPPO deployments, in the Northern Hemisphere, optimized aging timescales are less than half a day for BC emitted from tropical and mid-latitude source regions, and about 1 week for BC emitted from high latitude regions in all seasons except summer. We find that East Asian emissions contribute most to the BC loading over the North Pacific, while South American, African and Australian emissions dominate BC loadings over the South Pacific. Dominant source regions contributing to BC loadings in other parts of the globe are also assessed. The lifetime of BC originating from East Asia (i.e., the world's largest BC emitter) is found to be only 2.2 days, much shorter than the global average lifetime of 4.9 days, making East Asia's contribution to global burden only 36 % of BC from the second largest emitter, Africa. Thus, evaluating only relative emission rates without accounting for differences in aging time