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1

Azimuthal dependence of VLF propagation  

NASA Astrophysics Data System (ADS)

The World Wide Lightning Location Network (WWLLN) is used to measure the normalized lightning electric field at three network stations in order to examine the sferic attenuation between the stroke and the station. The electric field measurements are normalized to the radiated very low frequency (VLF) stroke energy to allow direct comparisons of the many stroke-station paths seen by WWLLN. Comparing past theoretical results and models show that WWLLN observes a stronger dependence of VLF propagation on magnetic azimuth compared to past work. The average attenuation over the water of eastward-propagating sferics is found to be 1.13±0.35 dB/Mm during the day and 0.71±0.68 dB/Mm at night, with westward-propagating sferics having average attenuation rates of 2.98±0.68 dB/Mm and 2.66±0.39 dB/Mm for day and night, respectively.

Hutchins, M. L.; Jacobson, Abram R.; Holzworth, Robert H.; Brundell, James B.

2013-09-01

2

Azimuthal dependence of the heavy quark initiated contributions to DIS  

SciTech Connect

We analyze the azimuthal dependence of the heavy-quark-initiated contributions to the lepton-nucleon deep inelastic scattering (DIS). First we derive the relations between the parton-level semi-inclusive structure functions and the helicity {gamma}*Q cross sections in the case of arbitrary values of the heavy quark mass. Then the azimuth-dependent O({alpha}{sub s}) lepton-quark DIS is calculated in the helicity basis. Finally, we investigate numerically the properties of the cos{phi} and cos2{phi} distributions caused by the photon-quark scattering (QS) contribution. It turns out that, contrary to the basic photon-gluon fusion (GF) component, the QS mechanism is practically cos2{phi}-independent. This fact implies that measurements of the azimuthal distributions in charm leptoproduction could directly probe the charm density in the proton.

Ananikyan, L. N.; Ivanov, N. Ya. [Yerevan Physics Institute, Alikhanian Br.2, 375036 Yerevan (Armenia)

2007-01-01

3

Dependence of ridge formation on trigger azimuth: Correlated emission model  

SciTech Connect

Ridge formation in near-side correlation in heavy-ion collisions is studied in the framework of a phenomenological model called the correlated emission model. Successive soft emissions due to jet-medium interaction lead to the enhancement of thermal partons that follow the local flow directions. The correlation between the flow direction and the semihard parton direction is the major factor that causes the ridge formation to depend on the trigger direction relative to the reaction plane. With the use of a few parameters we have been able to reproduce the data on the ridge yields as functions of the trigger azimuthal angle for different centralities. An inside-outside asymmetry function is proposed to further probe the characteristics of the azimuthal correlation function. Insights are provided for the understanding of some detailed aspects of the centrality dependence.

Chiu, Charles B. [Center for Particles and Fields and Department of Physics, University of Texas at Austin, Austin, Texas 78712 (United States); Hwa, Rudolph C. [Institute of Theoretical Science and Department of Physics, University of Oregon, Eugene, Oregon 97403-5203 (United States)

2009-03-15

4

The Azimuthal Dependence of Love and Rayleigh Wave Propagation in a Slightly Anisotropic Medium  

Microsoft Academic Search

where ois the angular frequency and 0 is the azimuth of the wave-number vector. This azimuthal dependence of the Love and Rayleigh wave phase velocities produces, in turn, a similar azimuthal dependence of the Love and Rayleigh wave group velocities. In view of the accumulating evidence from seismic refraction surveys of upper mantle anisotropy under oceans, the theory may be

Martin L. Smith; F. A. Dahlen

1973-01-01

5

Polarization Dependent Azimuthal Scattering From Tilted Fibre Bragg Gratings  

NASA Astrophysics Data System (ADS)

Polarization sensitive mode coupling characteristics of tilted fibre Bragg gratings (FBGs) have been exploited to develop a number of useful devices including fibre polarimeters, gain flattening filters, spectrum analyzers, polarization dependent loss (PDL) compensators, reconfigurable optical add / drop multiplexers (ROADM), as well as interferometric, and surface plasmon based sensors. Recently it was demonstrated that a single grating structure could couple the light guided in a fibre to two azimuthally separated, polarization independent, radiated beams. However the reasons for such behaviour had not been fully explained, precluding the complete understanding, exploitation and optimization of this phenomenon. This thesis explains the mechanisms underlying such behaviour through a thorough analytical examination of an existing equation formulated with the Volume Current Method (VCM), quantifying the degree to which a tilted FBG's radiation field is directionally dependent on the phase matching characteristics of a grating's three-dimensional structure as well as the polarization dependent dipole response of the medium itself. Examination of the equation's parameter space, revealed the possibility of three-beam azimuthal responses as well, and resulted in some guidelines for the design and optimization of these devices. Experimental measurements of the out-tapped field are also provided, clearly confirming these theoretical findings and reporting the fabrication of a three-beam azimuthal response grating for the first time. Drawing upon these advances, an improved polarimeter design is proposed that samples more than four detected beams with only two tilted FBGs, theoretically resulting in average Stokes vector error reductions of roughly 20%, facilitating monitoring at lower signal to noise ratios (SNRs). Finally, this thesis undertakes an analysis and re-derivation of the VCM formulation itself, designed to expand its applicability to FBGs written with ultrafast pulsed lasers, address some of the potentially limiting assumptions identified by Li et al, and provide users with computationally efficient formulae that are as accurate as possible.

Walker, Robert Bruce

6

Study of charge-dependent azimuthal correlations using reaction-plane-dependent balance functions  

NASA Astrophysics Data System (ADS)

STAR has recently reported charge-dependent azimuthal correlations that are sensitive to the charge separation effect in Au+Au collisions at \\sqrt{s_NN} = 200 GeV. Qualitatively, these results agree with some of the theoretical predictions for local parity violation in heavy-ion collisions. However, a study using reaction-plane-dependent balance functions shows an alternative origin of this signal. The balance function, which measures the correlation between oppositely charged pairs, is sensitive to the mechanisms of charge formation and the subsequent relative diffusion of the balancing charges. The reaction-plane-dependent balance function measurements can be related to STAR's charge-dependent azimuthal correlations. We report reaction-plane-dependent balance functions for Au+Au collisions at \\sqrt{s_NN} = 200, 62.4, 39, 11.5 and 7.7 GeV using the STAR detector. The model of Schlichting and Pratt incorporating local charge conservation and elliptic flow reproduces most of the three-particle azimuthal correlation results at 200 GeV. The experimental charge-dependent azimuthal charge correlations observed at 200 GeV can be explained in terms of local charge conservation and elliptic flow.

Wang, Hui; STAR Collaboration

2011-12-01

7

Depth dependent azimuthal anisotropy in the western US upper mantle  

NASA Astrophysics Data System (ADS)

We present the results of a joint inversion of long period seismic waveforms and SKS splitting measurements for 3D lateral variations of anisotropy in the upper mantle beneath the western US, incorporating recent datasets generated by the USArray deployment as well as other permanent and temporary stations in the region. We find that shallow azimuthal anisotropy closely reflects plate motion generated shear in the asthenosphere in the shallow upper mantle (70-150 km depth), whereas at depths greater than 150 km, it is dominated by northward and upward flow associated with the extension of the East Pacific Rise under the continent, constrained to the east by the western edge of the North American craton, and to the north, by the presence of the East-West trending subduction zone. In particular, the depth-integrated effects of this anisotropy explain the apparent circular pattern of SKS splitting measurements observed in Nevada without the need to invoke any local anomalous structures.

Yuan, Huaiyu; Romanowicz, Barbara

2010-12-01

8

Temporal and azimuthal dependence of sound propagation in shallow water with internal waves  

Microsoft Academic Search

The short time scale (minutes) and azimuthal dependence of sound wave propagation in shallow water regions due to internal waves is examined. Results from the shallow water acoustics in random media (SWARM-95) experiment are presented that reflect these dependencies. Time-dependent internal waves are modeled using the dnoidal solution to the nonlinear internal wave equations, so that the effects of both

M. Badiey; Y. Mu; J. Lynch; J. Apel; S. Wolf

2002-01-01

9

Azimuthal dependence of collective expansion for symmetric heavy-ion collisions.  

PubMed

Detailed studies of the azimuthal dependence of the mean fragment and flow energies in the Au+Au and Xe+CsI systems are reported as a function of incident energy and centrality. Comparisons between data and model calculations show that the flow energy values along different azimuthal directions could be viewed as snapshots of the fireball expansion with different exposure times. For the same number of participating nucleons more transversally elongated participant shapes from the heavier system produce less collective transverse energy. Good agreement with Boltzmann-Uehling-Uhlenbeck calculations is obtained for a soft nuclear equation of state. PMID:14995843

Stoicea, G; Petrovici, M; Andronic, A; Herrmann, N; Alard, J P; Basrak, Z; Barret, V; Bastid, N; Caplar, R; Crochet, P; Dupieux, P; Dzelalija, M; Fodor, Z; Hartmann, O; Hildenbrand, K D; Hong, B; Kecskemeti, J; Kim, Y J; Kirejczyk, M; Korolija, M; Kotte, R; Kress, T; Lebedev, A; Leifels, Y; Lopez, X; Merschmeier, M; Neubert, W; Pelte, D; Rami, F; Reisdorf, W; Schüll, D; Seres, Z; Sikora, B; Sim, K S; Simion, V; Siwek-Wilczy?ska, K; Smolyankin, V; Stockmeier, M; Wi?niewski, K; Wohlfarth, D; Yushmanov, I; Zhilin, A; Danielewicz, P

2004-02-20

10

Energy dependence of the freeze-out eccentricity from the azimuthal dependence of HBT at STAR  

NASA Astrophysics Data System (ADS)

Non-central heavy-ion collisions create an out-of-plane-extended participant zone that expands toward a more round state as the system evolves. The recent RHIC beam energy scan at \\sqrt{s_{NN}} of 7.7, 11.5 and 39 GeV provides an opportunity to explore the energy dependence of the freeze-out eccentricity. The new low-energy data from STAR complement high statistics data sets at \\sqrt{s_{NN}} of 62.4 and 200 GeV. Hanbury Brown-Twiss (HBT) interferometry allows us to determine the size of pion-emitting source regions. The dependence of the HBT radius parameters on the azimuthal angle relative to the reaction plane has been extracted. These dependences can be related to the freeze-out eccentricity. The new results from STAR are consistent with a monotonically decreasing freeze-out eccentricity and constrain any minimum, suggested by previously available data, to lie in the range between 11.5 and 39 GeV. Of several models, UrQMD appears to best predict the STAR and AGS data.

Anson, Christopher; STAR Collaboration

2011-12-01

11

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

SciTech Connect

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.

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

12

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

NASA Astrophysics Data System (ADS)

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.

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

2012-11-01

13

Inversion of azimuthally dependent NMO velocity in transversely isotropic media with a tilted axis of symmetry  

SciTech Connect

Just as the transversely isotropic model with a vertical symmetry axis (VTI media) is typical for describing horizontally layered sediments, transverse isotropy with a tilted symmetry axis (TTI) describes dipping TI layers (such as tilted shale beds near salt domes) or crack systems. P-wave kinematic signatures in TTI media are controlled by the velocity V{sub PO} in the symmetry direction, Thomsen's anisotropic coefficients {xi} and {delta}, and the orientation (tilt {nu} and azimuth {beta}) of the symmetry axis. Here, the authors show that all five parameters can be obtained from azimuthally varying P-wave NMO velocities measured for two reflectors with different dips and/or azimuths (one of the reflectors can be horizontal). The shear-wave velocity V{sub SO} in the symmetry direction, which has negligible influence on P-wave kinematic signatures, can be found only from the moveout of shear waves. Using the exact NMO equation, the authors examine the propagation of errors in observed moveout velocities into estimated values of the anisotropic parameters and establish the necessary conditions for a stable inversion procedure. Since the azimuthal variation of the NMO velocity is elliptical, each reflection event provides them with up to three constraints on the model parameters. Generally, the five parameters responsible for P-wave velocity can be obtained from two P-wave ellipses, but the feasibility of the moveout inversion strongly depends on the tilt {nu}. While most of the analysis is carried out for a single layer, the authors also extend the inversion algorithm to vertically heterogeneous TTI media above a dipping reflector using the generalized Dix equation. A synthetic example for a strongly anisotropic, stratified TTI medium demonstrates a high accuracy of the inversion.

Grechka, V.; Tsvankin, I.

2000-02-01

14

Scaling behavior of the azimuthal and centrality dependencies of jet production in heavy-ion collisions  

SciTech Connect

For heavy-ion collisions at the BNL Relativistic Heavy Ion Collider (RHIC) a scaling behavior is found in the dependencies on azimuthal angle phi and impact parameter b for pion production at high p{sub T} essentially independent of the hadronization process. The scaling variable is in terms of a dynamical path length xi that takes into account detailed properties of geometry, medium density, and probability of hard scattering. It is shown in the recombination model how the nuclear modification factor depends on the average xi-bar(phi,b). The data for pi{sup 0} production at p{sub T}=4-5 and 7-8 GeV/c at RHIC are shown to exhibit the same scaling behavior as found in the model calculation. Extension to back-to-back dijet production has been carried out, showing the existence of xi-bar scaling also in the away-side yield per trigger. At the CERN Large Hadron Collider the hard-parton density can be high enough to realize the likelihood of recombination of shower partons arising from neighboring jets. It is shown that such two-jet recombination can cause strong violation of xi-bar scaling. Furthermore, the large value of R{sub AA} that exceeds 1 can become a striking signature of such a hadronization process at high energy.

Hwa, Rudolph C. [Institute of Theoretical Science and Department of Physics, University of Oregon, Eugene, Oregon 97403-5203 (United States); Yang, C. B. [Institute of Theoretical Science and Department of Physics, University of Oregon, Eugene, Oregon 97403-5203 (United States); Institute of Particle Physics, Hua-Zhong Normal University, Wuhan 430079 (China)

2010-02-15

15

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

SciTech Connect

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.

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

16

Rapidity and centrality dependence of azimuthal correlations in high energy d+Au collisions  

NASA Astrophysics Data System (ADS)

We discuss azimuthal correlations in dAu collisions at different rapidities and centralities and argue that experimentally observed depletion of the back-to-back correlation peak can be quantitatively explained by gluon saturation in the Color Glass Condensate of the gold nucleus.

Tuchin, Kirill

2011-04-01

17

Dependence of nuclear diffraction on the azimuthal angle: (002)- and (0010)-reflections of YIG  

Microsoft Academic Search

Nuclear diffraction of synchrotron radiation has been investigated using YIG single crystals in different scattering geometries.\\u000a Time resolved quantum beat spectra of pure nuclear (002) and (0010) Bragg reflections were observed in a set-up where the\\u000a hyperfine interaction was kept constant, while the azimuthal angle in the (001) surface between the [100] axis and the scattering\\u000a plane (k\\u000a in,k\\u000a out)

H. D. Rüter; R. Rüffer; R. Hollatz; W. Sturhahn; E. Gerdau

1990-01-01

18

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

NASA Astrophysics Data System (ADS)

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.

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

19

A Low Temperature Two-Axis Goniometer for Azimuth Dependent Studies  

SciTech Connect

A novel insert was developed for top-loading liquid helium cryostats that allows a combined {+-}90 deg. sample tilt with a full 360 deg. azimuthal rotation. This sample stick is operational down to 1.5 K and was primarily designed for X-ray scattering in reflecting geometry. The device not being intended for scanning but positioning purposes, motion precision, resolution and repeatability specifications were relaxed to 0.1 deg. and readily achieved. This setup was initially designed for a specific cryostat and implemented at beamline ID20 of the ESRF but it can be easily adapted to similar top loading cryostats including cryomagnets. Initial results on the low temperature phases of CeB6 are presented.

Yakhou, Flora; Bernard, Pascal; Valade, Jean-Paul; Deen, Pascale P. [European Synchrotron Radiation Facility - BP 220, 38043 Grenoble Cedex 9 (France); Harris, Alistair [Etudes et Conception Mecaniques - Les Coings, 38210 Montaud (France); Lapertot, Gerard [Commissariat a l'Energie Atomique, Departement de Recherche Fondamentale sur la Matiere Condensee, SPSMS, 38054 Grenoble Cedex 9 (France)

2007-01-19

20

System Size and Beam Energy Dependence of Azimuthal Anisotropy from PHENIX  

SciTech Connect

We present azimuthal anisotropy measurements in Au+Au and Cu+Cu collisions at {radical}s{sub NN} = 62.4 and 200 GeV. Comparison between reaction plane and cumulant {upsilon}{sub 2} measurements in Au+Au collisions at {radical}s{sub NN} = 200 GeV show that non-flow contributions, originating mainly from jets, influence the extracted {upsilon}{sub 2} for p{sub T} {approx}> 3.5 GeV/c. Number of constituent quark (NCQ) scaling of {upsilon}{sub 2}, when studied as a function of transverse kinetic energy KE{sub T}, is seen to hold for Au+Au collisions at {radical}s{sub NN} = 62.4 and 200 GeV and for Cu+Cu collisions at {radical}s{sub NN} = 200 GeV for KE{sub T} {approx}< 1 GeV/c. Differential hexadecupole flow {upsilon}{sub 4} seems to exhibit scaling with integral {upsilon}{sub 2} for centrality {le} 40% as has been observed for differential {upsilon}{sub 2}.

Issah, Michael [Stony Brook University (SUNY) & Vanderbilt University; Cianciolo, Vince [ORNL; Awes, Terry C [ORNL; Efremenko, Yuri V [ORNL; Enokizono, Akitomo [Lawrence Livermore National Laboratory (LLNL); Read Jr, Kenneth F [ORNL; Silvermyr, David O [ORNL; Sorensen, Soren P [University of Tennessee, Knoxville (UTK); Stankus, Paul W [ORNL; Young, Glenn R [ORNL; PHENIX, Collaboration [The

2008-01-01

21

Multiplicity dependence of azimuthal distributions for 36Ar+197Au collisions at E/A=35 MeV  

NASA Astrophysics Data System (ADS)

Collisions between 36Ar projectile and 197Au target nuclei at E/A=35 MeV have been studied with the Michigan State University Miniball, a 4? phoswich array with a low detection threshold. Azimuthal distributions of charged particles with respect to the reaction plane are determined via the transverse-momentum-tensor method. Dependence on the kinetic energy of the emitted particles, the collision geometry, and the associated charged particle multiplicity is investigated. Corrections for the intrinsic resolution of the experimental reaction plane determination are applied. Scaling implied by the coalescence model is explored and the data are compared to the results of microscopic calculations within the Boltzmann-Uehling-Uhlenbeck theory.

Tsang, M. B.; Bowman, D. R.; Carlin, N.; Danielewicz, P.; Gelbke, C. K.; Gong, W. G.; Kim, Y. D.; Lynch, W. G.; Phair, L.; de Souza, R. T.; Zhu, F.

1993-06-01

22

Longitudinal polarization-dependent coupling of light from an optical fiber to a side-bonded planar proximity detector: application to integrated azimuthally distributed multidetector photopolarimeters  

Microsoft Academic Search

An in-line integrated fiber-optic photopolarimeter (IFOP) is described for the complete measurement of the state of polarization (SOP) of light. The IFOP consists of four azimuthally distributed side-bonded planar proximity detectors (SBPPDs), each of which develops an electrical signal proportional to the polarization-dependent fraction of light that it absorbs from the fiber guide. The four outputs thus developed determine the

R. M. A. Azzam

1990-01-01

23

The cost of transportation`s oil dependence  

SciTech Connect

Transportation is critical to the world`s oil dependence problem because of the large share of world oil it consumes and because of its intense dependence on oil. This paper will focus on the economic costs of transportation`s oil dependence.

Greene, D.L.

1995-05-01

24

Time dependent transport in nanostructures  

NASA Astrophysics Data System (ADS)

Using the Lagrange-function representation [1] we present time-dependent density functional calculations of the transport properties of nanostructures. To avoid the complications related to the semiinfinite leads a complex absorbing potential (CAP) is added to the Hamiltonian [2,3]. This transformation leads to an effectively closed system which is computationally manageable. We will compare the results of the time dependent approach to those of time independent approaches for prototypical molecular devices such as benzene ring between gold electrodes and nanotubes.[4pt] [1] K. Varga, Z. Zhang, S.T. Pantelides, Phys. Rev. Lett. 93, 176403 (2004).[0pt] [2] K. Varga, S.T. Pantelides, Phys. Rev. Lett. 98, 076804 (2007).[0pt] [3] J. A. Driscoll, K. Varga, Phys. Rev. B.

Varga, Kalman

2009-03-01

25

Azimuthal plasma flow in the Kronian magnetosphere  

NASA Astrophysics Data System (ADS)

We study the azimuthal plasma velocity in Saturn's magnetosphere between 3 and 13 Saturnian radii by analysing energetic particle injection events using data of the Magnetospheric Imaging Instrument (MIMI) onboard the Cassini spacecraft. During such events high energetic plasma is transported into the inner part of the magnetosphere. This transport may be evoked by the interchange instability which could be identified as the generation process of injections near Io in the Jovian system. Due to the magnetic drifts, the injected particles begin to disperse and leave an imprint in the electron as well as in the ion spectrograms of the MIMI data. The shape of these profiles strongly depends on the azimuthal velocity distribution of the magnetospheric plasma and the age of the injection event. Comparison of theoretically computed dispersion profiles with observed ones enables us to characterize the azimuthal flow of the plasma. The measured flow profile clearly shows that the plasma tends to subcorotate. Knowledge of the flow profile and the ages of each injection event enables us to calculate the location where the energetic particles were injected into the inner magnetosphere. The night and morning sector are favoured by injections.

Mueller, A.; Saur, J. S.; Krupp, N.; Mitchell, D. G.; Krimigis, S. M.

2009-12-01

26

Azimuthal dependence of pion source radii in Pb+Au collisions at 158A GeV/c  

SciTech Connect

We present results of a two-pion correlation analysis performed with the Pb+Au collision data collected by the upgraded CERES experiment in the fall of 2000. The analysis was done in bins of the reaction centrality and the pion azimuthal emission angle with respect to the reaction plane. The pion source, deduced from the data, is slightly elongated in the direction perpendicular to the reaction plane, similarly as was observed at the Brookhaven National Laboratory Alternating Gradient Synchrotron and Relativistic Heavy Ion Collider.

Adamova, D.; Kushpil, V.; Sumbera, M. [Nuclear Physics Institute of ASCR, 25068 Rez (Czech Republic); Agakichiev, G.; Belaga, V.; Fomenko, K.; Panebrattsev, Y.; Petchenova, O.; Shimansky, S.; Yurevich, V. [Joint Institute for Nuclear Research, RU-141980 Dubna (Russian Federation); Andronic, A.; Braun-Munzinger, P.; Garabatos, C.; Hering, G.; Holeczek, J.; Maas, A.; Marin, A.; Miskowiec, D.; Rak, J.; Sako, H. [GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, D-64291 Darmstadt (Germany)] (and others)

2008-12-15

27

14 CFR 171.315 - Azimuth monitor system requirements.  

Code of Federal Regulations, 2013 CFR

...ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) NAVIGATIONAL FACILITIES NON-FEDERAL NAVIGATION FACILITIES Microwave Landing System (MLS) § 171.315 Azimuth monitor system requirements. (a) The approach azimuth or back...

2013-01-01

28

Binding protein-dependent transport systems  

Microsoft Academic Search

Bacterial binding protein-dependent transport systems are the best characterized members of a superfamily of transporters which are structurally, functionally, and evolutionary related to each other. These transporters are not only found in bacteria but also in yeasts, plants, and animals including man, and include both import and export systems. Although any single system is relatively specific, different systems handle very

C. F. Higgins; S. C. Hyde; M. M. Mimmack; U. Gileadi; D. R. Gill; M. P. Gallagher

1990-01-01

29

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

SciTech Connect

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.

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

30

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

SciTech Connect

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 sq root(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 P violation.

Abelev, B. I.; Barannikova, O.; Betts, R. R.; Garcia-Solis, E. J.; Hofman, D. J.; Hollis, R. S.; Iordanova, A.; Kauder, K.; Suarez, M. C. [University of Illinois at Chicago, Chicago, Illinois 60607 (United States); Aggarwal, M. M.; Bhati, A. K.; Kumar, L.; Pruthi, N. K. [Panjab University, Chandigarh 160014 (India); Ahammed, Z.; Chattopadhyay, S.; Dutta Mazumdar, M. R.; Ganti, M. S.; Ghosh, P.; Mohanty, B.; Nayak, T. K. [Variable Energy Cyclotron Centre, Kolkata 700064 (India)

2010-05-15

31

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

SciTech Connect

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 {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 P violation.

Abelev, B. I.; Aggarwal, M. M.; Ahammed, Z.; Alakhverdyants, A. V.; Anderson, B. D.; Bridgeman, A.; Krueger, K.; Spinka, H. M.; Underwood, D. G.; STAR Collaboration (High Energy Physics); (Univ. of Illinois at Chicago); (Panjab Univ.); (Variable Energy Cyclotron Centre); (Kent State Univ.); (Univ. of Kentucky)

2010-01-01

32

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

SciTech Connect

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.

STAR Collaboration; Abelev, Betty

2010-07-05

33

14 CFR 171.313 - Azimuth performance requirements.  

Code of Federal Regulations, 2013 CFR

...ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) NAVIGATIONAL FACILITIES NON-FEDERAL NAVIGATION FACILITIES Microwave Landing System (MLS) § 171.313 Azimuth performance requirements. This section prescribes the performance...

2013-01-01

34

Phase and group velocities and Q of mantle Love and Rayleigh waves of the first two modes and their azimuthal dependences for the 1963 Kurile Islands earthquake  

NASA Astrophysics Data System (ADS)

Phase and group velocities and Q of mantle Love and Rayleigh waves from the 1963 Kurile Islands earthquake (Mw = 8.5) were determined over 37 great circle paths by a time variable filtering technique, in a period range 100-500 s for the fundamental modes and 100-275 s for the first higher modes. The preliminary reference Earth model (PREM) explains reasonably well the average dispersion results for the fundamental Love and Rayleigh waves. There exists a small, but significant inconsistency between the observation and the model for the first higher Love and Rayleigh waves. The Q structure of PREM is inconsistent with the observation for the fundamental Love waves, but explains other observations reasonably well. The dispersion of each mode shows a clear azimuthal dependence from which the four azimuthal windows were established. The phase and group velocity measurements for each window were, in general, shown to be mutually consistent. The azimuthal variations are largest for the first higher Rayleigh waves, indicating strong lateral heterogeneity in the structure of the low velocity zone. The first of the four windows is characterized by the largest fraction of Precambrian shields and the second window by the largest fraction of normal oceans. A comparison of these two windows may give some insight into deep lateral heterogeneity between continents and oceans. The observed phase and group velocities of the first window are systematically higher than those of the second window for the fundamental Love and Rayleigh waves at periods up to 400 s, and for the first higher Love and Rayleigh waves up to 175 s. Their differences are greatest for the first higher Rayleigh waves and least for the fundamental Rayleigh waves. Although the fundamental Rayleigh waves show the least velocity differences, their persistence up to a period of longer than 300 s is in striking contrast with some of the pure path phase velocities derived earlier for continents and oceans. A set of models for continents and oceans. PEM-C and PEM-O are not consistent with our observation. The third azimuthal window is characterized by trench-marginal seas and the fourth window by mountainous areas, typically the Asian high plateaus from northern China to the Middle East through Tibet. A comparison of these two windows gives some information about deep structural differences between subduction zones and continental collision zones, both belonging to plate convergence zones. For the fundamental and the first higher Love waves, the phase and group velocities for the third window are markedly low, whereas those for the fourth window are somewhat comparable to those for the second window. Slow Rayleigh waves are evident for two windows, with the fourth window apparently being the slowest for the fundamental Rayleigh above 200 s and for the first higher Rayleigh. For the fundamental Rayleigh waves, the third window is very slow below 200 s, but becomes progressively fast as the period increases and tends to be the fastest window around 400 s, suggesting a deep seated high velocity anomaly beneath trench-marginal seas. The dispersion characteristics of the fourth window indicate a thick high velocity lid with an extensive low velocity zone beneath it. The shield-like lithosphere, coupled with an extensive low velocity zone, may be a characteristic feature of continental collision zones. The particle motion of the fundamental Love waves was found not to be purely transverse to a great-circle connecting the epicenter to a station. The departure from the purely transverse motion is systematic among different periods, different G arrivals (G2, G3,...) and different stations, which may be interpreted as being due to lateral refraction.

Fukao, Yoshio; Kobayashi, Minoru

1983-04-01

35

Azimuthal anisotropy of the Pacific region  

NASA Astrophysics Data System (ADS)

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.

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

2006-10-01

36

Temperature dependence of fluid transport in nanopores  

NASA Astrophysics Data System (ADS)

Understanding the temperature-dependent nanofluidic transport behavior is critical for developing thermomechanical nanodevices. By using non-equilibrium molecular dynamics simulations, the thermally responsive transport resistance of liquids in model carbon nanotubes is explored as a function of the nanopore size, the transport rate, and the liquid properties. Both the effective shear stress and the nominal viscosity decrease with the increase of temperature, and the temperature effect is coupled with other non-thermal factors. The molecular-level mechanisms are revealed through the study of the radial density profile and hydrogen bonding of confined liquid molecules. The findings are verified qualitatively with an experiment on nanoporous carbon.

Xu, Baoxing; Wang, Binglei; Park, Taehyo; Qiao, Yu; Zhou, Qulan; Chen, Xi

2012-05-01

37

Dopamine transporter levels in cocaine dependent subjects  

Microsoft Academic Search

Cocaine use is a significant problem in the US and it is well established that cocaine binds to the dopamine transporter (DAT) in the brain. This study was designed to determine if the DAT levels measured by 99mTc TRODAT SPECT (single photon emission computed tomography) brain scans are altered in cocaine dependent subjects and to explore clinical correlates of such

Paul Crits-Christoph; Andrew Newberg; Nancy Wintering; Karl Ploessl; Mary Beth Connolly Gibbons; Sarah Ring-Kurtz; Robert Gallop

2008-01-01

38

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.

39

Dissipative time-dependent quantum transport theory  

NASA Astrophysics Data System (ADS)

A dissipative time-dependent quantum transport theory is developed to treat the transient current through molecular or nanoscopic devices in presence of electron-phonon interaction. The dissipation via phonon is taken into account by introducing a self-energy for the electron-phonon coupling in addition to the self-energy caused by the electrodes. Based on this, a numerical method is proposed. For practical implementation, the lowest order expansion is employed for the weak electron-phonon coupling case and the wide-band limit approximation is adopted for device and electrodes coupling. The corresponding hierarchical equation of motion is derived, which leads to an efficient and accurate time-dependent treatment of inelastic effect on transport for the weak electron-phonon interaction. The resulting method is applied to a one-level model system and a gold wire described by tight-binding model to demonstrate its validity and the importance of electron-phonon interaction for the quantum transport. As it is based on the effective single-electron model, the method can be readily extended to time-dependent density functional theory.

Zhang, Yu; Yam, Chi Yung; Chen, GuanHua

2013-04-01

40

Temperature Dependent Kinetics DNA Charge Transport  

NASA Astrophysics Data System (ADS)

Charge transport (CT) through DNA has been extensively studied, and yet the mechanism of this process is still not yet fully understood. Besides the benefits of understanding charge transport through this fundamental molecule, further understanding of this process will elucidate the biological implications of DNA CT and advance sensing technology. Therefore, we have investigated the temperature dependence of DNA CT by measuring the electrochemistry of DNA monolayers modified with a redox-active probe. By using multiplexed electrodes on silicon chips, we compare square wave voltammetry of distinct DNA sequences under identical experimental conditions. We vary the probe length within the well matched DNA duplex in order to investigate distance dependent kinetics. This length dependent study is a necessary step to understanding the dominant mechanism behind DNA CT. Using a model put forth by O'Dea and Osteryoung and applying a nonlinear least squares analysis we are able to determine the charge transfer rates (k), transfer coefficients (?), and the total surface concentration (&*circ;) of the DNA monolayer. Arrhenius like behavior is observed for the multiple probe locations, and the results are viewed in light of and compared to the prominent charge transport mechanisms.

Wohlgamuth, Chris; McWilliams, Marc; Slinker, Jason

2012-10-01

41

Centrality dependence of dihadron correlations and azimuthal anisotropy harmonics in PbPb collisions at ?{s_{NN}}= 2.76 TeV  

NASA Astrophysics Data System (ADS)

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 ( p T) and collision centrality over a broad range in relative pseudorapidity (? ?) and the full range of relative azimuthal angle (? ?). The observed two-dimensional correlation structure in ? ? and ? ? is characterised by a narrow peak at (? ?,? ?)?(0,0) from jet-like correlations and a long-range structure that persists up to at least |? ?|=4. An enhancement of the magnitude of the short-range jet peak is observed with increasing centrality, especially for particles of p T 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 p T?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 p T of 1-3 GeV/ c, as a function of the trigger particle p T up to 20 GeV/ c and over the full centrality range.

Chatrchyan, S.; Khachatryan, V.; Sirunyan, A. M.; Tumasyan, A.; Adam, W.; Bergauer, T.; Dragicevic, M.; Erö, J.; Fabjan, C.; Friedl, M.; Frühwirth, R.; Ghete, V. M.; Hammer, J.; Hoch, M.; Hörmann, N.; Hrubec, J.; Jeitler, M.; Kiesenhofer, W.; Knapitsch, A.; Krammer, M.; Liko, D.; Mikulec, I.; Pernicka, M.; Rahbaran, B.; Rohringer, C.; Rohringer, H.; Schöfbeck, R.; Strauss, J.; Taurok, A.; Teischinger, F.; Wagner, P.; Waltenberger, W.; Walzel, G.; Widl, E.; Wulz, C.-E.; Mossolov, V.; Shumeiko, N.; Suarez Gonzalez, J.; Bansal, S.; Benucci, L.; Cornelis, T.; De Wolf, E. A.; Janssen, X.; Luyckx, S.; Maes, T.; Mucibello, L.; Ochesanu, S.; Roland, B.; Rougny, R.; Selvaggi, M.; Van Haevermaet, H.; Van Mechelen, P.; Van Remortel, N.; Van Spilbeeck, A.; Blekman, F.; Blyweert, S.; D'Hondt, J.; Gonzalez Suarez, R.; Kalogeropoulos, A.; Maes, M.; Olbrechts, A.; Van Doninck, W.; Van Mulders, P.; Van Onsem, G. P.; Villella, I.; Charaf, O.; Clerbaux, B.; De Lentdecker, G.; Dero, V.; Gay, A. P. R.; Hammad, G. H.; Hreus, T.; Léonard, A.; Marage, P. E.; Thomas, L.; Vander Velde, C.; Vanlaer, P.; Wickens, J.; Adler, V.; Beernaert, K.; Cimmino, A.; Costantini, S.; Garcia, G.; Grunewald, M.; Klein, B.; Lellouch, J.; Marinov, A.; Mccartin, J.; Ocampo Rios, A. A.; Ryckbosch, D.; Strobbe, N.; Thyssen, F.; Tytgat, M.; Vanelderen, L.; Verwilligen, P.; Walsh, S.; Zaganidis, N.; Basegmez, S.; Bruno, G.; Caudron, J.; Ceard, L.; De Favereau De Jeneret, J.; Delaere, C.; du Pree, T.; Favart, D.; Forthomme, L.; Giammanco, A.; Grégoire, G.; Hollar, J.; Lemaitre, V.; Liao, J.; Militaru, O.; Nuttens, C.; Pagano, D.; Pin, A.; Piotrzkowski, K.; Schul, N.; Beliy, N.; Caebergs, T.; Daubie, E.; Alves, G. A.; De Jesus Damiao, D.; Pol, M. E.; Souza, M. H. G.; Aldá Júnior, W. L.; Carvalho, W.; Custódio, A.; Da Costa, E. M.; De Oliveira Martins, C.; Fonseca De Souza, S.; Matos Figueiredo, D.; Mundim, L.; Nogima, H.; Oguri, V.; Prado Da Silva, W. L.; Santoro, A.; Silva Do Amaral, S. M.; Soares Jorge, L.; Sznajder, A.; Anjos, T. S.; Bernardes, C. A.; Dias, F. A.; Fernandez Perez Tomei, T. R.; Gregores, E. M.; Lagana, C.; Marinho, F.; Mercadante, P. G.; Novaes, S. F.; Padula, Sandra S.; Genchev, V.; Iaydjiev, P.; Piperov, S.; Rodozov, M.; Stoykova, S.; Sultanov, G.; Tcholakov, V.; Trayanov, R.; Vutova, M.; Dimitrov, A.; Hadjiiska, R.; Karadzhinova, A.; Kozhuharov, V.; Litov, L.; Pavlov, B.; Petkov, P.; Bian, J. G.; Chen, G. M.; Chen, H. S.; Jiang, C. H.; Liang, D.; Liang, S.; Meng, X.; Tao, J.; Wang, J.; Wang, J.; Wang, X.; Wang, Z.; Xiao, H.; Xu, M.; Zang, J.; Zhang, Z.; Asawatangtrakuldee, C.; Ban, Y.; Guo, S.; Guo, Y.; Li, W.; Liu, S.; Mao, Y.; Qian, S. J.; Teng, H.; Wang, S.; Zhu, B.; Zou, W.; Cabrera, A.; Gomez Moreno, B.; Osorio Oliveros, A. F.; Sanabria, J. C.; Godinovic, N.; Lelas, D.; Plestina, R.; Polic, D.; Puljak, I.; Antunovic, Z.; Dzelalija, M.; Kovac, M.; Brigljevic, V.; Duric, S.; Kadija, K.; Luetic, J.; Morovic, S.; Attikis, A.; Galanti, M.; Mousa, J.; Nicolaou, C.; Ptochos, F.; Razis, P. A.; Finger, M.; Finger, M.; Assran, Y.; Ellithi Kamel, A.; Khalil, S.; Mahmoud, M. A.; Radi, A.; Hektor, A.; Kadastik, M.; Müntel, M.; Raidal, M.; Rebane, L.; Tiko, A.; Azzolini, V.; Eerola, P.; Fedi, G.; Voutilainen, M.; Czellar, S.; Härkönen, J.; Heikkinen, A.; Karimäki, V.; Kinnunen, R.; Kortelainen, M. J.; Lampén, T.; Lassila-Perini, K.; Lehti, S.; Lindén, T.; Luukka, P.; Mäenpää, T.; Peltola, T.; Tuominen, E.; Tuominiemi, J.; Tuovinen, E.; Ungaro, D.; Wendland, L.; Banzuzi, K.; Korpela, A.; Tuuva, T.; Sillou, D.; Besancon, M.; Choudhury, S.; Dejardin, M.; Denegri, D.; Fabbro, B.; Faure, J. L.; Ferri, F.; Ganjour, S.; Givernaud, A.; Gras, P.; Hamel de Monchenault, G.; Jarry, P.; Locci, E.; Malcles, J.; Marionneau, M.; Millischer, L.; Rander, J.; Rosowsky, A.; Shreyber, I.; Titov, M.; Baffioni, S.; Beaudette, F.; Benhabib, L.; Bianchini, L.; Bluj, M.; Broutin, C.; Busson, P.; Charlot, C.; Daci, N.; Dahms, T.; Dobrzynski, L.; Elgammal, S.; Granier de Cassagnac, R.; Haguenauer, M.; Miné, P.; Mironov, C.; Ochando, C.; Paganini, P.; Sabes, D.; Salerno, R.; Sirois, Y.; Thiebaux, C.; Veelken, C.; Zabi, A.; Agram, J.-L.; Andrea, J.; Bloch, D.; Bodin, D.; Brom, J.-M.; Cardaci, M.; Chabert, E. C.; Collard, C.; Conte, E.; Drouhin, F.; Ferro, C.; Fontaine, J.-C.; Gelé, D.; Goerlach, U.; Greder, S.; Juillot, P.; Karim, M.; Le Bihan, A.-C.; Van Hove, P.; Fassi, F.; Mercier, D.; Baty, C.; Beauceron, S.; Beaupere, N.; Bedjidian, M.; Bondu, O.; Boudoul, G.; Boumediene, D.; Brun, H.; Chasserat, J.; Chierici, R.; Contardo, D.; Depasse, P.; El Mamouni, H.; Falkiewicz, A.; Fay, J.; Gascon, S.; Gouzevitch, M.; Ille, B.; Kurca, T.; Le Grand, T.; Lethuillier, M.; Mirabito, L.; Perries, S.; Sordini, V.; Tosi, S.; Tschudi, Y.; Verdier, P.; Viret, S.

2012-05-01

42

Azimuth and Elevation Applet  

NSDL National Science Digital Library

This applet allows users to see what the elevation, noon elevation, and azimuth of the Sun is for specific locations (requested by city or latitude and longitude) and time zone for the current date. This program also shows how long the Sun will be above or below the horizon for the current date and the location the user chooses.

Giesen, Juergen

43

Azimuthal variation of dilatancy  

Microsoft Academic Search

In triaxial laboratory tests, variation of circumferential strain in dilatant granite may reach 100% or more at high stresses. Pseudoelastic compliances s13 and s23 in the plane perpendicular to the maximum stress may differ by a factor of 2-10. Given the magnitude of these differences, in situ azimuthal variation of dilatancy should be the observed rule rather that the exception.

Kate Hadley

1975-01-01

44

Temperature Dependence of DNA Charge Transport  

NASA Astrophysics Data System (ADS)

Charge transport (CT) through DNA has been extensively studied, and yet the mechanism of this process is still not yet fully understood. DNA CT has been utilized in sensing proteins and DNA fragments, and it has been postulated that it may assist DNA damage prevention and repair. Besides the benefits of understanding charge transport through this fundamental molecule, further understanding of this process will elucidate the biological implications of DNA CT and advance sensing technology. Therefore, we have investigated the temperature dependence of DNA CT by measuring the electrochemistry of DNA monolayers modified with a redox-active probe. By using multiplexed electrodes on silicon chips, we compare the cyclic and square wave voltammetry of distinct DNA sequences under identical experimental conditions. Accordingly, we compare well matched DNA duplexes to those containing a single base pair mismatch, which has been shown to attenuate CT. The yield of CT is shown to follow Arrhenius behavior, with increased activation energies for mismatches that structurally distort the duplex. These observations suggest that charge transport is thermally activated and highly dependent upon DNA conformation.

Wohlgamuth, Chris; McWilliams, Marc; Slinker, Jason

2011-10-01

45

Time-dependent transport through molecular junctions  

NASA Astrophysics Data System (ADS)

We investigate transport properties of molecular junctions under two types of bias-a short time pulse or an ac bias-by combining a solution for Green's functions in the time domain with electronic structure information coming from ab initio density functional calculations. We find that the short time response depends on lead structure, bias voltage, and barrier heights both at the molecule-lead contacts and within molecules. Under a low frequency ac bias, the electron flow either tracks or leads the bias signal (resistive or capacitive response) depending on whether the junction is perfectly conducting or not. For high frequency, the current lags the bias signal due to the kinetic inductance. The transition frequency is an intrinsic property of the junctions.

Ke, San-Huang; Liu, Rui; Yang, Weitao; Baranger, Harold U.

2010-06-01

46

Azimuthal Anisotropy and the QGP  

SciTech Connect

Study of azimuthal anisotropy have played very important role at RHIC(Relativistic Heavy Ion Collider) Physics. The large azimuthal anisotropy is the proof of very early thermalization of the system which cannot be obtained without introducing interactions at the partonic level. Quark number scaling of the azimuthal anisotropy suggests a new particle production mechanism characteristic in dense matter.

Miake, Yasuo [Institute of Physics, University of Tsukuba, Tsukuba, 305-8571 (Japan)

2006-11-02

47

Spin Dependent Transport in Chemically Modified Graphene  

NASA Astrophysics Data System (ADS)

Graphene is extremely sensitive to the presence of adatoms on the surface due to its truly 2D nature. This provides a powerful technique to alter and control properties of graphene through intentional chemical modification. In particular, exposure to fluorine adatoms results in the formation of a covalent bond between carbon and fluorine atoms, transforming spinto spbonds. This modification dramatically effects charge transport in graphene, opening a band gap and transforming graphene from semi-metal to semiconductor at high fluorine coverage [1,2]. Fluorination may also have serious impact on spin dependent properties. It has been suggested that covalently bonded adatoms result in increased spin relaxation [3] and may be a contributing factor to the low spin lifetimes experimentally measured in graphene. In this study we perform spin transport measurements on graphene grown via chemical vapor deposition. The graphene surface is systematically modified through exposure to XeFand its affect on spin injection efficiency, spin lifetimes and spin coherence lengths are monitored in order to build a more complete understanding of spin transport in fluorinated graphene.[4pt] [1] J. T. Robinson, et al., Nano Lett., 3001 (2010)[0pt] [2] X. Hong, et al., Phys. Rev. B., 085410 (2011)[0pt] [3] A. H. Castro Neto and F. Guinea, Phys. Rev. Lett., 026804 (2009).

McCreary, Kathleen; van Térve, Olaf; Friedman, Adam; Cobas, Enrique; Li, Connie; Hanbicki, Aubrey; Robinson, Jeremy; Jonker, Berend T.

2013-03-01

48

Magnetic field dependence of asymmetry-induced transport: A new approach  

SciTech Connect

A new technique is used to experimentally study the dependence of asymmetry-induced radial particle flux {gamma} on an axial magnetic field B in a modified Malmberg-Penning trap. This dependence is complicated by the fact that B enters the physics in at least two places: in the asymmetry-induced first order radial drift velocity v{sub r}=E{sub {theta}}/B and in the zeroth order azimuthal drift velocity v{sub {theta}}=E{sub r}/B. To separate these, it is assumed that the latter always enters the physics in the combination {omega}-l{omega}{sub R}, where {omega}{sub R}(r)=v{sub {theta}}/r is the column rotation frequency and {omega} and l are the asymmetry frequency and azimuthal mode number, respectively. Points where {omega}-l{omega}{sub R}=0 are then selected from a {gamma} versus r versus {omega} data set, thus insuring that any function of this combination is constant. When the selected flux is plotted versus the density gradient {nabla}n, a roughly linear dependence is observed, showing that the assumption is valid and that the diffusive contribution to the transport has been isolated. The slope of a least-squares fitted line then gives the diffusion coefficient D{sub 0} for the selected flux. Varying the magnetic field, it is found that D{sub 0}{proportional_to}B{sup -1.33{+-}}{sup 0.05}. This does not match the scaling predicted by resonant particle transport theory.

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

2008-03-15

49

Functional and Molecular Characteristics of Na+-dependent Nucleoside Transporters  

Microsoft Academic Search

Nucleoside transporters play a critical role in the absorption, disposition, and targeting of therapeutically used nucleosides and nucleoside analogs. This review is focused on the Na+-dependent, concentrative nucleoside transporters which are found in a variety of cells including renal, intestinal and hepatic epithelia. Five major Na+-dependent nucleoside transporter subtypes have been characterized in isolated tissue preparations: Nl is purine selective;

Juan Wang; Marci E. Schaner; Silja Thomassen; Sheng-Fang Su; Micheline Piquette-Miller; Kathleen M. Giacomini

1997-01-01

50

Relating micro ave backscatter azimuth modulation to surface properties of the greenland ice sheet  

Microsoft Academic Search

Azimuth modulation of the normalized radar cross- section in satellite data sets over Greenland is investigated. Data sets from the NASA Scatterometer (NSCAT) and from the European Remote Sensing Advanced Microwave Instrument (ERS) are employed. Azimuth dependence is clearly observed. The largest azimuth dependence occurs in the C-band ERS data with peak-to-peak azimuth modulations up to 3.0 dB. The Ku-

Ivan S. Ashcraft; David G. Long

2003-01-01

51

Anisotropic structures in New Zealand: Back-azimuth dependent SKS splitting measurements and crustal stress related rotation of the fast direction.  

NASA Astrophysics Data System (ADS)

A main geological feature in the North Island of New Zealand is the Central Volcanic Region (CVR), which is a continental margin arc system. It spans, wedge-like, from Mt. Ruapehu Volcano to White Island in the north-east and to East Coromandel Peninsula in the north-west. Measurements of seismic anisotropy across the western border were made to find out more about the crust and mantle structure and the relation between anisotropy and boundary deformation in this region, using data from the Central North Island Passive Seismic Experiment recorded during 2001. The Victoria University of Wellington component consisted of three broadband and six triggered short-period seismometers recording continuously. The broadband stations were positioned in a line across the western edge of the CVR with a station spacing of 10 km; 2 stations were moved after six months to get five stations in a line. The Institute of Geological and Nuclear Sciences provided data for selected teleseismic events for 8 more stations, spanning the entire CVR. Shear-wave splitting measurements were used to determine the orientation of the anisotropic system. The results from the broadband teleseismic data show that the splitting fast directions are consistent from station to station, and that delay times are larger within the CVR, suggesting that either anisotropy is stronger within the CVR, or is enhanced by coherent crustal anisotropy. However, the splitting parameters change for a specific back-azimuth. Comparison with other studies showed that for most of New Zealand, events from most back-azimuths show a consistent northeast-southwest, trench-parallel fast direction; but events coming from an 80 deg back-azimuth yield an almost north-south fast direction, possibly explained by regional anisotropy in the D'' layer. Splitting measurements of the local earthquakes yield a rotation of the fast direction from N-S for stations within the CVR to NW-SE for the stations west of the CVR. This is probably caused by crustal stress changes at the western border of the CVR.

Hofmann, S. D.; Savage, M. K.; Gledhill, K. R.; Wenzel, F.

2003-04-01

52

Two-particle azimuthal angle correlations and azimuthal charge balance function in relativistic heavy ion collisions  

SciTech Connect

The two-particle azimuthal angle correlation (TPAC) and azimuthal charge balance function (ACBF) are used to study the anisotropic expansion in relativistic heavy ion collisions. It is demonstrated by the relativistic quantum molecular dynamics (RQMD) model and a multi-phase transport (AMPT) model that the small-angle correlation in TPAC indeed presents anisotropic expansion, and the large-angle (or back-to-back) correlation is mainly due to global momentum conservations. The AMPT model reproduces the observed TPAC, but the RQMD model fails to reproduce the strong correlations in both small and large azimuthal angles. The width of ACBF from RQMD and AMPT models decreases from peripheral to central collisions, consistent with experimental data, but in contrast to the expectation from thermal model calculations. The ACBF is insensitive to anisotropic expansion. It is a probe for the mechanism of hadronization, similar to the charge balance function in rapidity.

Huang Yanping [Institute of High Energy Physics, CAS, Beijing 100049 (China); Graduate University of Chinese Academy of Sciences, Beijing 100049 (China); Institute of Particle Physics, Hua-Zhong Normal University, Wuhan 430079 (China); Na Li; Du Jiaxin; Li Zhiming; Wu Yuanfang [Institute of Particle Physics, Hua-Zhong Normal University, Wuhan 430079 (China)

2009-05-15

53

Azimuthally Sensitive Femtoscopy and {nu}2  

SciTech Connect

I investigate the correlation between spatial and flow anisotropy in determining the elliptic flow and azimuthal dependence of the HBT correlation radii in non-central nuclear collisions. It is shown that the correlation radii are in most cases dominantly sensitive to the anisotropy in space. In case of {nu}2, the correlation depends strongly on particle species. A procedure for disentangling the spatial and the flow anisotropy is proposed.

Tomasik, Boris [Niels Bohr Institute, Blegdamsvej 17, 2100 Copenhagen O (Denmark); Ustav jaderne fyziky AVCR, 25068 Rez (Czech Republic)

2006-04-11

54

Multiplicity, average transverse momentum, and azimuthal anisotropy in U + U collisions at SNN=200 GeV using a multiphase transport model  

NASA Astrophysics Data System (ADS)

Using a multiphase transport (AMPT) model that includes the implementation of deformed uranium nuclei, we have studied the centrality dependence of the charged particle multiplicity (Nch, dNch/d?), average transverse momentum (), eccentricity (?2), triangularity (?3), their fluctuations, elliptic flow (v2), and triangular flow (v3) for different configurations of U+U collisions at midrapidity for sNN = 200 GeV. The calculations have been done for both the default and string-melting versions of the AMPT model. The results are compared to the corresponding observations from Au+Au collisions. We find that for the U+U collisions dNch/d? at midrapidity is enhanced by about 15%-40% depending on the collision and model configuration chosen, compared to Au+Au collisions. Within the several configurations studied, the tip-to-tip collisions lead to the largest values of Nch, transverse energy (ET), and . Both and its fluctuation show a rich centrality dependence, whereas little variation is observed for and its fluctuations. The U+U side-on-side collision configuration provides maximum values of and minimum values of eccentricity fluctuations, whereas for peripheral collisions and mid-central collisions minimum values of and the maximum value of eccentricity fluctuations are observed for the body-to-body configuration and the tip-to-tip configuration has a minimum value of and a maximum value of eccentricity fluctuations for central collisions. The calculated v2 value closely correlates with the eccentricity in the model. It is smallest for the body-to-body configuration in peripheral and mid-central collisions while it is minimum for the tip-to-tip configuration in central collisions. For peripheral collisions v2 in U+U can be about 40% larger than in Au+Au whereas for central collisions it can be a factor of 2 higher depending on the collision configuration. It is also observed that v3(pT) is higher for tip-to-tip and body-to-body configurations compared to other systems for the collision centrality studied.

Haque, Md. Rihan; Lin, Zi-Wei; Mohanty, Bedangadas

2012-03-01

55

Intraflagellar transport and cilia-dependent diseases  

Microsoft Academic Search

Intraflagellar transport involves the movement of large protein particles along ciliary microtubules and is required for the assembly and maintenance of eukaryotic cilia and flagella. Intraflagellar-transport defects in the mouse cause a range of diseases including polycystic kidney disease, retinal degeneration and the laterality abnormality situs inversus, highlighting the important role that motile, sensory and primary cilia play in vertebrates.

Gregory J Pazour; Joel L Rosenbaum

2002-01-01

56

Measurement of the Azimuthal Angle Dependence of Inclusive Jet Yields in Pb+Pb Collisions at sNN=2.76TeV with the ATLAS Detector  

NASA Astrophysics Data System (ADS)

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 measured the ?? dependence of jet yields in 0.14nb-1 of sNN=2.76TeV Pb+Pb collisions at the LHC for jet transverse momenta pT>45GeV in different collision centrality bins using an underlying event subtraction procedure that accounts for elliptic flow. The variation of the jet yield with ?? was characterized by the parameter, v2jet, and the ratio of out-of-plane (??˜?/2) to in-plane (??˜0) yields. Nonzero v2jet values were measured in all centrality bins for pT<160GeV. The jet yields are observed to vary by as much as 20% between in-plane and out-of-plane directions.

Aad, G.; Abajyan, T.; Abbott, B.; Abdallah, J.; Abdel Khalek, S.; Abdinov, O.; Aben, R.; Abi, B.; Abolins, M.; AbouZeid, O. S.; Abramowicz, H.; Abreu, H.; Abulaiti, Y.; Acharya, B. S.; Adamczyk, L.; Adams, D. L.; Addy, T. N.; Adelman, J.; Adomeit, S.; Adye, T.; Aefsky, S.; Agatonovic-Jovin, T.; Aguilar-Saavedra, J. A.; Agustoni, M.; Ahlen, S. P.; Ahmad, A.; Ahsan, M.; Aielli, G.; Åkesson, T. P. A.; Akimoto, G.; Akimov, A. V.; Alam, M. A.; Albert, J.; Albrand, S.; Alconada Verzini, M. J.; Aleksa, M.; Aleksandrov, I. N.; Alessandria, F.; Alexa, C.; Alexander, G.; Alexandre, G.; Alexopoulos, T.; Alhroob, M.; Aliev, M.; Alimonti, G.; Alio, L.; Alison, J.; Allbrooke, B. M. M.; Allison, L. J.; Allport, P. P.; Allwood-Spiers, S. E.; Almond, J.; Aloisio, A.; Alon, R.; Alonso, A.; Alonso, F.; Altheimer, A.; Alvarez Gonzalez, B.; Alviggi, M. G.; Amako, K.; Amaral Coutinho, Y.; Amelung, C.; Ammosov, V. V.; Amor Dos Santos, S. P.; Amorim, A.; Amoroso, S.; Amram, N.; Anastopoulos, C.; Ancu, L. S.; Andari, N.; Andeen, T.; Anders, C. F.; Anders, G.; Anderson, K. J.; Andreazza, A.; Andrei, V.; Anduaga, X. S.; Angelidakis, S.; Anger, P.; Angerami, A.; Anghinolfi, F.; Anisenkov, A. V.; Anjos, N.; Annovi, A.; Antonaki, A.; Antonelli, M.; Antonov, A.; Antos, J.; Anulli, F.; Aoki, M.; Aperio Bella, L.; Apolle, R.; Arabidze, G.; Aracena, I.; Arai, Y.; Arce, A. T. H.; Arfaoui, S.; Arguin, J.-F.; Argyropoulos, S.; Arik, E.; Arik, M.; Armbruster, A. J.; Arnaez, O.; Arnal, V.; Artamonov, A.; Artoni, G.; Arutinov, D.; Asai, S.; Asbah, N.; Ask, S.; Åsman, B.; Asquith, L.; Assamagan, K.; Astalos, R.; Astbury, A.; Atkinson, M.; Atlay, N. B.; Auerbach, B.; Auge, E.; Augsten, K.; Aurousseau, M.; Avolio, G.; Axen, D.; Azuelos, G.; Azuma, Y.; Baak, M. A.; Bacci, C.; Bach, A. M.; Bachacou, H.; Bachas, K.; Backes, M.; Backhaus, M.; Backus Mayes, J.; Badescu, E.; Bagiacchi, P.; Bagnaia, P.; Bai, Y.; Bailey, D. C.; Bain, T.; Baines, J. T.; Baker, O. K.; Baker, S.; Balek, P.; Balli, F.; Banas, E.; Banerjee, Sw.; Banfi, D.; Bangert, A.; Bansal, V.; Bansil, H. S.; Barak, L.; Baranov, S. P.; Barber, T.; Barberio, E. L.; Barberis, D.; Barbero, M.; Bardin, D. Y.; Barillari, T.; Barisonzi, M.; Barklow, T.; Barlow, N.; Barnett, B. M.; Barnett, R. M.; Baroncelli, A.; Barone, G.; Barr, A. J.; Barreiro, F.; Barreiro Guimarães da Costa, J.; Bartoldus, R.; Barton, A. E.; Bartsch, V.; Basye, A.; Bates, R. L.; Batkova, L.; Batley, J. R.; Battistin, M.; Bauer, F.; Bawa, H. S.; Beale, S.; Beau, T.; Beauchemin, P. H.; Beccherle, R.; Bechtle, P.; Beck, H. P.; Becker, K.; Becker, S.; Beckingham, M.; Becks, K. H.; Beddall, A. J.; Beddall, A.; Bedikian, S.; Bednyakov, V. A.; Bee, C. P.; Beemster, L. J.; Beermann, T. A.; Begel, M.; Belanger-Champagne, C.; Bell, P. J.; Bell, W. H.; Bella, G.; Bellagamba, L.; Bellerive, A.; Bellomo, M.; Belloni, A.; Beloborodova, O. L.; Belotskiy, K.; Beltramello, O.; Benary, O.; Benchekroun, D.; Bendtz, K.; Benekos, N.; Benhammou, Y.; Benhar Noccioli, E.; Benitez Garcia, J. A.; Benjamin, D. P.; Bensinger, J. R.; Benslama, K.; Bentvelsen, S.; Berge, D.; Bergeaas Kuutmann, E.; Berger, N.; Berghaus, F.; Berglund, E.; Beringer, J.; Bernard, C.; Bernat, P.; Bernhard, R.; Bernius, C.; Bernlochner, F. U.; Berry, T.; Bertella, C.; Bertolucci, F.; Besana, M. I.; Besjes, G. J.; Bessidskaia, O.; Besson, N.; Bethke, S.; Bhimji, W.; Bianchi, R. M.; Bianchini, L.; Bianco, M.; Biebel, O.; Bieniek, S. P.; Bierwagen, K.; Biesiada, J.; Biglietti, M.; Bilbao De Mendizabal, J.; Bilokon, H.; Bindi, M.; Binet, S.; Bingul, A.; Bini, C.; Bittner, B.; Black, C. W.; Black, J. E.; Black, K. M.; Blackburn, D.; Blair, R. E.; Blanchard, J.-B.; Blazek, T.; Bloch, I.; Blocker, C.; Blocki, J.; Blum, W.; Blumenschein, U.; Bobbink, G. J.; Bobrovnikov, V. S.; Bocchetta, S. S.; Bocci, A.; Boddy, C. R.; Boehler, M.; Boek, J.; Boek, T. T.; Boelaert, N.; Bogaerts, J. A.; Bogdanchikov, A. G.; Bogouch, A.; Bohm, C.; Bohm, J.; Boisvert, V.; Bold, T.; Boldea, V.; Bolnet, N. M.; Bomben, M.; Bona, M.; Boonekamp, M.; Bordoni, S.; Borer, C.; Borisov, A.; Borissov, G.; Borri, M.; Borroni, S.; Bortfeldt, J.; Bortolotto, V.; Bos, K.; Boscherini, D.; Bosman, M.; Boterenbrood, H.; Bouchami, J.; Boudreau, J.; Bouhova-Thacker, E. V.; Boumediene, D.; Bourdarios, C.; Bousson, N.; Boutouil, S.; Boveia, A.; Boyd, J.; Boyko, I. R.; Bozovic-Jelisavcic, I.; Bracinik, J.; Branchini, P.; Brandt, A.; Brandt, G.; Brandt, O.; Bratzler, U.; Brau, B.; Brau, J. E.; Braun, H. M.; Brazzale, S. F.; Brelier, B.; Bremer, J.; Brendlinger, K.; Brenner, R.; Bressler, S.; Bristow, T. M.; Britton, D.; Brochu, F. M.; Brock, I.; Brock, R.; Broggi, F.; Bromberg, C.; Bronner, J.; Brooijmans, G.; Brooks, T.; Brooks, W. K.; Brost, E.; Brown, G.; Brown, J.; Bruckman de Renstrom, P. A.

2013-10-01

57

Azimuthal Anisotropy of pi Production in Au+Au Collisions at s_NN = 200 GeV: Path-length Dependence of Jet-Quenching and the Role of Initial Geometry  

SciTech Connect

We have measured the azimuthal anisotropy of {pi}{sup 0} production for 1 < p{sub T} < 18 GeV/c for Au+Au collisions at {radical}s{sub NN} = 200 GeV. The observed anisotropy shows a gradual decrease for 3 {approx}< p {approx}< 7-10 GeV/c, but remains positive beyond 10 GeV/c. The magnitude of this anisotropy is underpredicted, up to at least {approx}10 GeV/c, by current perturbative QCD (PQCD) energy-loss model calculations. An estimate of the increase in anisotropy expected from initial-geometry modification due to gluon saturation effects and fluctuations is insufficient to account for this discrepancy. Calculations that implement a path-length dependence steeper than what is implied by current PQCD energy-loss models show reasonable agreement with the data.

Adare, A. [University of Colorado, Boulder; Awes, Terry C [ORNL; Cianciolo, Vince [ORNL; Efremenko, Yuri [University of Tennessee, Knoxville (UTK) & Oak Ridge National Laboratory (ORNL); Enokizono, Akitomo [Oak Ridge National Laboratory (ORNL); Read Jr, Kenneth F [ORNL; Silvermyr, David O [ORNL; Sorensen, Soren P [University of Tennessee, Knoxville (UTK); Stankus, Paul W [ORNL; PHENIX, Collaboration [The

2010-01-01

58

Anomalous frequency-dependent transport in composites  

Microsoft Academic Search

We consider transport in metal-insulator composites where the metallic component has a range of conductivities described by the distribution function h(sigma)~sigma-alpha (0

P. M. Hui; D. Stroud

1985-01-01

59

Involvement of glial glutamate transporters in morphine dependence.  

PubMed

There are several lines of evidence implying the involvement of the central glutamatergic system in morphine dependence. Extracellular glutamate released from nerve terminals is counterbalanced by glutamate transporters in neurons (EAAC1 and EAAT4) and glial cells (GLT-1 and GLAST), thereby modulating the glutamatergic system and protecting neurons from an excitotoxic action of glutamate. Here we show that a glial glutamate transporter GLT-1 could be involved in physical and psychological morphine dependence. By Northern blot analysis, the expression of glial glutamate transporter GLT-1, but not GLAST, mRNA was decreased in the striatum/nucleus accumbens (NAc) and thalamus of morphine-dependent rats. Subcutaneous administration of a glutamate transporter activator suppressed the development of physical morphine dependence and morphine-induced conditioned place preference. Intracerebroventricular administration of a glutamate transporter inhibitor to morphine-dependent rats facilitated the expression of naloxone-precipitated morphine withdrawal-induced somatic signs and conditioned place aversion. Furthermore, gene transfer techniques using recombinant adenoviruses revealed that GLT-1 in the locus coeruleus and NAc shell plays inhibitory roles in physical and psychological morphine dependence, respectively. These findings may provide evidence that a glial glutamate transporter GLT-1 could be a new target for preventing physical and psychological morphine dependence. PMID:15542740

Nakagawa, Takayuki; Satoh, Masamichi

2004-10-01

60

Material processing with pulsed radially and azimuthally polarized laser radiation  

Microsoft Academic Search

We report on the generation of radially and azimuthally polarized Q-switched laser radiation and its application in material\\u000a processing. The power levels were sufficiently high to study micro-hole drilling in different metals. Depending on the optical\\u000a properties of the metal, either radial or azimuthal polarization shows the best efficiency and the effect is attributed to\\u000a waveguiding. For steel, a comparison

M. Meier; V. Romano; T. Feurer

2007-01-01

61

Azimuthal asymmetries in deep inelastic scattering at HERA  

SciTech Connect

The distribution of the azimuthal angle of charged and neutral hadrons has been studied in the hadronic centre-of-mass system for neutral current deep inelastic ep scattering with the ZEUS detector at HERA using an integrated luminosity of 45.21 pb-1. Measurements of the dependence of the moments of the azimuthal distribution on the pseudorapidity and minimum transverse energy of the final state hadrons are presented using the energy flow method.

Ukleja, Artur [Hoza 69, 00681 Warsaw (Poland)

2005-10-06

62

TonB-Dependent Transporters Expressed by Neisseria gonorrhoeae.  

PubMed

Neisseria gonorrhoeae causes the common sexually transmitted infection, gonorrhea. This microorganism is an obligate human pathogen, existing nowhere in nature except in association with humans. For growth and proliferation, N. gonorrhoeae requires iron and must acquire this nutrient from within its host. The gonococcus is well-adapted for growth in diverse niches within the human body because it expresses efficient transport systems enabling use of a diverse array of iron sources. Iron transport systems facilitating the use of transferrin, lactoferrin, and hemoglobin have two components: one TonB-dependent transporter and one lipoprotein. A single component TonB-dependent transporter also allows N. gonorrhoeae to avail itself of iron bound to heterologous siderophores produced by bacteria within the same ecological niche. Other TonB-dependent transporters are encoded by the gonococcus but have not been ascribed specific functions. The best characterized iron transport system expressed by N. gonorrhoeae enables the use of human transferrin as a sole iron source. This review summarizes the molecular mechanisms involved in gonococcal iron acquisition from human transferrin and also reviews what is currently known about the other TonB-dependent transport systems. No vaccine is available to prevent gonococcal infections and our options for treating this disease are compromised by the emergence of antibiotic resistance. Because iron transport systems are critical for the survival of the gonococcus in vivo, the surface-exposed components of these systems are attractive candidates for vaccine development or therapeutic intervention. PMID:21747812

Cornelissen, Cynthia Nau; Hollander, Aimee

2011-05-27

63

TonB-Dependent Transporters Expressed by Neisseria gonorrhoeae  

PubMed Central

Neisseria gonorrhoeae causes the common sexually transmitted infection, gonorrhea. This microorganism is an obligate human pathogen, existing nowhere in nature except in association with humans. For growth and proliferation, N. gonorrhoeae requires iron and must acquire this nutrient from within its host. The gonococcus is well-adapted for growth in diverse niches within the human body because it expresses efficient transport systems enabling use of a diverse array of iron sources. Iron transport systems facilitating the use of transferrin, lactoferrin, and hemoglobin have two components: one TonB-dependent transporter and one lipoprotein. A single component TonB-dependent transporter also allows N. gonorrhoeae to avail itself of iron bound to heterologous siderophores produced by bacteria within the same ecological niche. Other TonB-dependent transporters are encoded by the gonococcus but have not been ascribed specific functions. The best characterized iron transport system expressed by N. gonorrhoeae enables the use of human transferrin as a sole iron source. This review summarizes the molecular mechanisms involved in gonococcal iron acquisition from human transferrin and also reviews what is currently known about the other TonB-dependent transport systems. No vaccine is available to prevent gonococcal infections and our options for treating this disease are compromised by the emergence of antibiotic resistance. Because iron transport systems are critical for the survival of the gonococcus in vivo, the surface-exposed components of these systems are attractive candidates for vaccine development or therapeutic intervention.

Cornelissen, Cynthia Nau; Hollander, Aimee

2011-01-01

64

A velocity-dependent anomalous radial transport model for (2-D, 2-V) kinetic transport codes  

NASA Astrophysics Data System (ADS)

Plasma turbulence constitutes a significant part of radial plasma transport in magnetically confined plasmas. This turbulent transport is modeled in the form of anomalous convection and diffusion coefficients in fluid transport codes. There is a need to model the same in continuum kinetic edge codes [such as the (2-D, 2-V) transport version of TEMPEST, NEO, and the code being developed by the Edge Simulation Laboratory] with non-Maxwellian distributions. We present an anomalous transport model with velocity-dependent convection and diffusion coefficients leading to a diagonal transport matrix similar to that used in contemporary fluid transport models (e.g., UEDGE). Also presented are results of simulations corresponding to radial transport due to long-wavelength ExB turbulence using a velocity-independent diffusion coefficient. A BGK collision model is used to enable comparison with fluid transport codes.

Bodi, Kowsik; Krasheninnikov, Sergei; Cohen, Ron; Rognlien, Tom

2008-11-01

65

Time-dependent density functional theory for quantum transport  

NASA Astrophysics Data System (ADS)

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.

Kwok, Yanho; Zhang, Yu; Chen, GuanHua

2013-07-01

66

Azimuthal plasma flow in the Kronian magnetosphere  

NASA Astrophysics Data System (ADS)

We study the azimuthal plasma velocity in Saturn's magnetosphere between 3 and 13 Saturn radii (Rs) by analyzing energetic particle injection events using data of the Magnetospheric Imaging Instrument (MIMI) onboard the Cassini spacecraft in orbit around Saturn. Due to the magnetic drifts, the injected particles at various energies begin to disperse and leave an imprint in the electron as well as in the ion energy spectrograms of the MIMI instrument. The shape of these profiles strongly depends on the azimuthal velocity distribution of the magnetospheric plasma and the age of the injection event. Comparison of theoretically computed dispersion profiles with observed ones enables us to characterize the azimuthal flow of the plasma. The measured flow profile clearly shows that the plasma subcorotates with velocities as low as 80% of full corotation at radial distances between 8 Rs to 13 Rs. With knowledge of the flow profile and the ages of each injection event we can calculate the location where the energetic particles were injected into the inner magnetosphere. The night and morning sector of the Kronian magnetosphere are preferred regions for the generation of hot plasma injections.

Müller, A. L.; Saur, J.; Krupp, N.; Roussos, E.; Mauk, B. H.; Rymer, A. M.; Mitchell, D. G.; Krimigis, S. M.

2010-08-01

67

Solving time-dependent quantum transport problems with balance equations  

NASA Astrophysics Data System (ADS)

Within the framework of the balance equation method for closed electric circuits, we have extended the formalism to model time-dependent transport in mesoscopic structures. The time-dependent quantum mechanical balance equations for momentum and energy are solved by using a time-parametrized boosted statistical operator. The boosted statistical operator has already been successfully applied for describing steady-state quantum transport and is now extended to tackle time-dependent quantum transport problems. As an example we numerically studied the response of a homogeneous quantum wire to a voltage step and a voltage oscillation. For the voltage step we obtain the overshoot effect for sufficiently large voltages, while the voltage oscillation shows the transient response of the quantum wire. The numerical examples clearly show that the balance equation formalism is a powerful tool in modelling quantum transport under various circumstances.

Soree, Bart; Magnus, Wim

2004-03-01

68

Measurement of the Azimuthal Angle Dependence of Inclusive Jet Yields in Pb+Pb Collisions at sqrt[s_{NN}]=2.76??TeV with the ATLAS Detector.  

PubMed

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 measured the ?? dependence of jet yields in 0.14??nb^{-1} of sqrt[s_{NN}]=2.76??TeV Pb+Pb collisions at the LHC for jet transverse momenta p_{T}>45??GeV in different collision centrality bins using an underlying event subtraction procedure that accounts for elliptic flow. The variation of the jet yield with ?? was characterized by the parameter, v_{2}^{jet}, and the ratio of out-of-plane (????/2) to in-plane (???0) yields. Nonzero v_{2}^{jet} values were measured in all centrality bins for p_{T}<160??GeV. The jet yields are observed to vary by as much as 20% between in-plane and out-of-plane directions. PMID:24160592

Aad, G; Abajyan, T; Abbott, B; Abdallah, J; Abdel Khalek, S; Abdinov, O; Aben, R; Abi, B; Abolins, M; Abouzeid, O S; Abramowicz, H; Abreu, H; Abulaiti, Y; Acharya, B S; Adamczyk, L; Adams, D L; Addy, T N; Adelman, J; Adomeit, S; Adye, T; Aefsky, S; Agatonovic-Jovin, T; Aguilar-Saavedra, J A; Agustoni, M; Ahlen, S P; Ahmad, A; Ahsan, M; Aielli, G; Akesson, T P A; Akimoto, G; Akimov, A V; Alam, M A; Albert, J; Albrand, S; Alconada Verzini, M J; Aleksa, M; Aleksandrov, I N; Alessandria, F; Alexa, C; Alexander, G; Alexandre, G; Alexopoulos, T; Alhroob, M; Aliev, M; Alimonti, G; Alio, L; Alison, J; Allbrooke, B M M; Allison, L J; Allport, P P; Allwood-Spiers, S E; Almond, J; Aloisio, A; Alon, R; Alonso, A; Alonso, F; Altheimer, A; Alvarez Gonzalez, B; Alviggi, M G; Amako, K; Amaral Coutinho, Y; Amelung, C; Ammosov, V V; Amor Dos Santos, S P; Amorim, A; Amoroso, S; Amram, N; Anastopoulos, C; Ancu, L S; Andari, N; Andeen, T; Anders, C F; Anders, G; Anderson, K J; Andreazza, A; Andrei, V; Anduaga, X S; Angelidakis, S; Anger, P; Angerami, A; Anghinolfi, F; Anisenkov, A V; Anjos, N; Annovi, A; Antonaki, A; Antonelli, M; Antonov, A; Antos, J; Anulli, F; Aoki, M; Aperio Bella, L; Apolle, R; Arabidze, G; Aracena, I; Arai, Y; Arce, A T H; Arfaoui, S; Arguin, J-F; Argyropoulos, S; Arik, E; Arik, M; Armbruster, A J; Arnaez, O; Arnal, V; Artamonov, A; Artoni, G; Arutinov, D; Asai, S; Asbah, N; Ask, S; Asman, B; Asquith, L; Assamagan, K; Astalos, R; Astbury, A; Atkinson, M; Atlay, N B; Auerbach, B; Auge, E; Augsten, K; Aurousseau, M; Avolio, G; Axen, D; Azuelos, G; Azuma, Y; Baak, M A; Bacci, C; Bach, A M; Bachacou, H; Bachas, K; Backes, M; Backhaus, M; Backus Mayes, J; Badescu, E; Bagiacchi, P; Bagnaia, P; Bai, Y; Bailey, D C; Bain, T; Baines, J T; Baker, O K; Baker, S; Balek, P; Balli, F; Banas, E; Banerjee, Sw; Banfi, D; Bangert, A; Bansal, V; Bansil, H S; Barak, L; Baranov, S P; Barber, T; Barberio, E L; Barberis, D; Barbero, M; Bardin, D Y; Barillari, T; Barisonzi, M; Barklow, T; Barlow, N; Barnett, B M; Barnett, R M; Baroncelli, A; Barone, G; Barr, A J; Barreiro, F; Barreiro Guimarães da Costa, J; Bartoldus, R; Barton, A E; Bartsch, V; Basye, A; Bates, R L; Batkova, L; Batley, J R; Battistin, M; Bauer, F; Bawa, H S; Beale, S; Beau, T; Beauchemin, P H; Beccherle, R; Bechtle, P; Beck, H P; Becker, K; Becker, S; Beckingham, M; Becks, K H; Beddall, A J; Beddall, A; Bedikian, S; Bednyakov, V A; Bee, C P; Beemster, L J; Beermann, T A; Begel, M; Belanger-Champagne, C; Bell, P J; Bell, W H; Bella, G; Bellagamba, L; Bellerive, A; Bellomo, M; Belloni, A; Beloborodova, O L; Belotskiy, K; Beltramello, O; Benary, O; Benchekroun, D; Bendtz, K; Benekos, N; Benhammou, Y; Benhar Noccioli, E; Benitez Garcia, J A; Benjamin, D P; Bensinger, J R; Benslama, K; Bentvelsen, S; Berge, D; Bergeaas Kuutmann, E; Berger, N; Berghaus, F; Berglund, E; Beringer, J; Bernard, C; Bernat, P; Bernhard, R; Bernius, C; Bernlochner, F U; Berry, T; Bertella, C; Bertolucci, F; Besana, M I; Besjes, G J; Bessidskaia, O; Besson, N; Bethke, S; Bhimji, W; Bianchi, R M; Bianchini, L; Bianco, M; Biebel, O; Bieniek, S P; Bierwagen, K; Biesiada, J; Biglietti, M; Bilbao De Mendizabal, J; Bilokon, H; Bindi, M; Binet, S; Bingul, A; Bini, C; Bittner, B; Black, C W; Black, J E; Black, K M; Blackburn, D; Blair, R E; Blanchard, J-B; Blazek, T; Bloch, I; Blocker, C; Blocki, J; Blum, W; Blumenschein, U; Bobbink, G J; Bobrovnikov, V S; Bocchetta, S S; Bocci, A; Boddy, C R; Boehler, M; Boek, J; Boek, T T; Boelaert, N; Bogaerts, J A; Bogdanchikov, A G; Bogouch, A; Bohm, C; Bohm, J; Boisvert, V; Bold, T; Boldea, V; Bolnet, N M; Bomben, M; Bona, M; Boonekamp, M; Bordoni, S; Borer, C; Borisov, A; Borissov, G; Borri, M; Borroni, S; Bortfeldt, J; Bortolotto, V; Bos, K; Boscherini, D; Bosman, M; Boterenbrood, H; Bouchami, J; Boudreau, J; Bouhova-Thacker, E V; Boumediene, D; Bourdarios, C; Bousson, N; Boutouil, S; Boveia, A; Boyd, J; Boyko, I R; Bozovic-Jelisavcic, I; Bracinik, J; Branchini, P; Brandt, A; Brandt, G; Brandt, O; Bratzler, U; Brau, B; Brau, J E; Braun, H M; Brazzale, S F; Brelier, B; Bremer, J; Brendlinger, K; Brenner, R; Bressler, S; Bristow, T M; Britton, D; Brochu, F M; Brock, I; Brock, R; Broggi, F; Bromberg, C; Bronner, J; Brooijmans, G; Brooks, T; Brooks, W K; Brost, E; Brown, G; Brown, J; Bruckman de Renstrom, P A; Bruncko, D; Bruneliere, R; Brunet, S; Bruni, A; Bruni, G; Bruschi, M; Bryngemark, L; Buanes, T; Buat, Q; Bucci, F; Buchanan, J; Buchholz, P; Buckingham, R M; Buckley, A G; Buda, S I; Budagov, I A; Budick, B; Bugge, L; Bulekov, O; Bundock, A C; Bunse, M; Buran, T; Burckhart, H; Burdin, S; Burgess, T; Burke, S; Busato, E; Büscher, V; Bussey, P; Buszello, C P; Butler, B; Butler, J M; Buttar, C M; Butterworth, J M; Buttinger, W; Byszewski, M; Cabrera Urbán, S; Caforio, D; Cakir, O; Calafiura, P; Calderini, G

2013-10-09

69

Time-dependent transport in Aharonov-Bohm interferometers  

NASA Astrophysics Data System (ADS)

A numerical approach is employed to explain transport characteristics in realistic, quantum Hall-based Aharonov-Bohm (AB) interferometers. Firstly, the spatial distribution of incompressible strips, and thus the current channels, are obtained by applying a self-consistent Thomas-Fermi method to a realistic heterostructure under quantized Hall conditions. Secondly, the time-dependent Schrödinger equation is solved for electrons injected in the current channels. Distinctive AB oscillations are found as a function of the magnetic flux. The oscillation amplitude strongly depends on the mutual distance between the transport channels and on their width. At an optimal distance the amplitude and thus the interchannel transport is maximized, which determines the maximum visibility condition. On the other hand, the transport is fully suppressed at magnetic fields corresponding to half-integer flux quanta. The results confirm the applicability of realistic AB interferometers as controllable current switches.

Kotimäki, V.; Cicek, E.; Siddiki, A.; Räsänen, E.

2012-05-01

70

A model for the azimuthal plasma velocity in Saturn's magnetosphere  

Microsoft Academic Search

We present a model for Saturn's magnetospheric azimuthal plasma velocities measured by Voyager 1 and 2. The observed velocity profiles deviate from full corotation and show two dips slightly outside the orbits of Dione and Rhea, for both spacecraft respectively. Our velocity model includes as sources for the deviation: radial mass transport,friction between magnetospheric ions and neutrals, and ion pickup.

Joachim Saur; Barry H. Mauk; F. M. Neubauer

2004-01-01

71

Position-dependent Effects of Polylysine on Sec Protein Transport*  

PubMed Central

The bacterial Sec protein translocation system catalyzes the transport of unfolded precursor proteins across the cytoplasmic membrane. Using a recently developed real time fluorescence-based transport assay, the effects of the number and distribution of positive charges on the transport time and transport efficiency of proOmpA were examined. As expected, an increase in the number of lysine residues generally increased transport time and decreased transport efficiency. However, the observed effects were highly dependent on the polylysine position in the mature domain. In addition, a string of consecutive positive charges generally had a more significant effect on transport time and efficiency than separating the charges into two or more charged segments. Thirty positive charges distributed throughout the mature domain resulted in effects similar to 10 consecutive charges near the N terminus of the mature domain. These data support a model in which the local effects of positive charge on the translocation kinetics dominate over total thermodynamic constraints. The rapid translocation kinetics of some highly charged proOmpA mutants suggest that the charge is partially shielded from the electric field gradient during transport, possibly by the co-migration of counter ions. The transport times of precursors with multiple positively charged sequences, or “pause sites,” were fairly well predicted by a local effect model. However, the kinetic profile predicted by this local effect model was not observed. Instead, the transport kinetics observed for precursors with multiple polylysine segments support a model in which translocation through the SecYEG pore is not the rate-limiting step of transport.

Liang, Fu-Cheng; Bageshwar, Umesh K.; Musser, Siegfried M.

2012-01-01

72

Range and resolution analysis of wide-azimuth angle decomposition  

Microsoft Academic Search

Imaging in complex media benefits from uniform illumination of the target from all possible directions. Moreover, it is desirable to recover reflectivity from seismic data as a function of incidence and azimuthal angles at every location over the reflector. Ap- plications of angle-dependent reflectivity include velocity and anisotropy estimation and amplitude versus angle (AVA) analysis. One way of constructing angle-dependent

Gabriela Melo; Paul Sava

2008-01-01

73

A simple method for inverting the azimuthal anisotropy of surface waves  

NASA Astrophysics Data System (ADS)

We investigate the problem of retrieving anisotropy as a function of depth in the mantle, from the observed azimuthal variations of Love and Rayleigh wave velocities. Following the approach of Smith and Dahlen, this azimuthal dependence is expressed in terms of a Fourier series of the azimuth ?. For the most general case of anisotropy (provided it is small enough), some simple linear combinations of the elastic tensor coefficients are shown to describe the total effect of anisotropy (both polarization anisotropy and azimuthal anisotropy) on the propagation of surface Waves. For the terms that do not depend on the azimuth the combinations are related to the elastic coefficients of a transversely isotropic mantle. For the azimuthal terms the relevant combinations are explicited. It is found that the partial derivatives of the azimuthal terms with respect to these combinations are easy to compute for they are proportional to the partial derivatives of a transversely isotropic model in the case of a plane-layered model. In a first approximation the same property holds true for a spherical earth and we calculate from PREM all the partial derivatives needed for performing the inversion of the azimuthal anisotropy of surface waves in the period range 50-300 s. It is observed that very shallow anisotropy can be responsible for substantial azimuthal variations up to the longest periods. With this approach it is also easy to compute the azimuthal variations of surface wave velocities produced by any anisotropic model. When a Ci j elastic tensor is chosen for the upper mantle, azimuthal variations up to 2% are obtained for Rayleigh waves. The azimuthal variations of Love wave velocities are very small. The 2 ? term of the azimuthal variations of Rayleigh wave velocities is the dominant term. Its fast axis corresponds to the fast axis of P waves.

Montagner, Jean-Paul; Nataf, Henri-Claude

1986-01-01

74

Spin-Dependent Transport through an Interacting Quantum Dot  

Microsoft Academic Search

We study the nonequilibrium spin transport through a quantum dot coupled to the magnetic electrodes. A formula for the spin-dependent current is obtained and is applied to discuss the linear conductance and magnetoresistance in the interacting regime. We show that the Kondo resonance and the correlation-induced spin splitting of the dot levels may be systematically controlled by internal magnetization in

Ping Zhang; Qi-Kun Xue; Yupeng Wang; X. C. Xie

2002-01-01

75

Glutamate Transporter 1: Target for the Treatment of Alcohol Dependence  

PubMed Central

Emerging evidence indicates that many aspects of alcohol and drug dependence involve changes in glutamate transmission. A number of studies have reported that drugs of abuse, including alcohol and cocaine, alter glutamate transport. Extracellular glutamate is regulated by a number of glutamate transporters in various brain regions. Of these transporters, glutamate transporter (GLT1) is a key player in the removal of most of the extracellular glutamate. Similar to neurodegenerative disease models, in which there is dysfunction of the glutamatergic excitatory system, the role of GLT1 has been tested in drug dependence models that show dysfunction of glutamate transmission. We and others have recently found that ceftriaxone, an FDA-approved drug known to elevate GLT1 expression, attenuates cue-induced cocaine relapse. Moreover, we recently found that alcohol-preferring rats treated with ceftriaxone showed a significant dose-dependent reduction in alcohol consumption. We also demonstrated that ceftriaxone-induced upregulation of GLT1 expression was associated with increases in glutamate uptake in Huntington’s disease mouse model. Importantly, ceftriaxone is currently in clinical trials for the treatment of amyotrophic lateral sclerosis. This review provides information about the potential therapeutic role of GLT1 for the treatment of alcohol abuse and dependence.

Rao, P.S.S.; Sari, Y.

2012-01-01

76

Cation-dependent nutrient transport in shrimp digestive tract.  

PubMed

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

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

2011-10-09

77

Azimuthal Anisotropy Results from STAR  

NASA Astrophysics Data System (ADS)

Recent advances in the studies of eventwise azimuthal anisotropy from STAR have been made possible by the high statistics 200 GeV Au + Au datasets taken in 2010 and by the broad range of energies recorded during the first phase of the RHIC beam energy scan. The high statistics full energy Au + Au data have allowed precision studies of flow. These include detailed studies of flow versus non-flow, results of elliptic flow at high pT, the ?2 contributions from jets, and elliptic flow of multi-strange hadrons. Data from the beam energy scan enables STAR to search for evidence of the first order phase transition and the onset of deconfinement through the energy systematics of directed flow, elliptic flow, and azimuthally sensitive HBT.

Cebra, Daniel

2013-05-01

78

Azimuthal anisotropy: The higher harmonics  

SciTech Connect

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.

Poskanzer, Arthur M.; STAR Collaboration

2004-03-12

79

Numerical simulation of time-dependent transport in graphene  

NASA Astrophysics Data System (ADS)

We present a numerical method for modeling time-dependent quantum transport in graphene. The time-dependent Schrodinger equation is solved with a pi-orbital-based atomistic tight-binding Hamiltonian. A novel variation of an alternating-direction semi-implicit scheme is employed on the hexagonal tight-binding lattice to maintain stability and conserve probability while achieving computational efficiency. Open boundaries including source terms to allow time-dependent non-equilibrium Green's function (NEGF) calculation of graphene devices will be discussed.

Reddy, Dharmendar; Jadaun, Priyamvada; Register, Leonard F.; Banerjee, Sanjay K.

2011-03-01

80

Bias-dependent oscillatory electron transport of monatomic sulfur chains  

NASA Astrophysics Data System (ADS)

The bias-dependent oscillatory electron transport of monatomic sulfur chains sandwiched between gold electrodes is investigated with density functional theory and non-equilibrium Green's function method. At zero bias, in contrast to the typical odd-even oscillations observed in most metallic chains, we find that the conductance oscillates with a period of four atoms. However, as the bias voltage is increased the current displays a two-atom periodicity. This emerges gradually, first for the longer chains and then, at voltages larger than 0.7 V, for lengths. The oscillatory behaviors are analyzed by the density of states and the energy-dependent and bias-dependent transmission coefficients.

Yu, Jing-Xin; Cheng, Yan; Sanvito, Stefano; Chen, Xiang-Rong

2012-03-01

81

Energy-dependent nickel transport by Clostridium thermoaceticum  

SciTech Connect

The transport of nickel was highly specific. Divalent cations did not compete with nickel for the transport site except cobalt at equimolar concentration relative to the nickel concentration. Stimulation occurred with some of the metals, particularly with cobalt and iron. Nickel internalized during the assay did not significantly label CO dehydrogenase. PAGE analysis of extracts from cells used in the transport assay revealed that nickel existed primarily in a low M/sub r/ form. /sup 63/NiCl/sub 2/ was observed to be transported by C. thermoaceticum via an energy-dependent mechanism. Glucose, fructose, and xylose supported transport and growth of the organism. Additionally, starvation or incubation with sugar alcohols had no apparent effect or were stimulatory to nickel transport. However, internal P/sub 1/ levels rose sharply while PP/sub 1/ levels dropped during starvation. ATP levels dropped at first, but increased as starvation commenced.Acetic acid was produced by cells that were incubated with glucose,but starved cells did not produce acetate

Lundie, L.L. Jr.

1987-01-01

82

Azimuthal plasma flow in the Kronian magnetosphere  

NASA Astrophysics Data System (ADS)

ABSTRACT Since the Voyager mission it is known that the magnetosphere of Saturn does not rigidly corotate outside 5 Rs. The velocity profiles show a clear breakdown of corotation [1]. However current data obtained by the Cassini spacecraft provide controversial results. The aim of our work is to develop an azimuthal profile for the plasma flow in the inner Kronian magnetosphere. For this purpose, data from the Magnetospheric Imaging Instrument (MIMI) onboard Cassini were analysed. Energetic particle injection events are observed between 3 and 11 Rs. In the data they are visible as dispersion profiles. The shape of these profiles depends, amongst others, on the azimuthal velocity of the magnetosphere [2]. We show how the superposition of the particle drifts with the trajectory of the spacecraft modifies the measured dispersion profiles. A comparison of the data with theoretically predicted profiles indicates that the magnetosphere does not rigidly corotate with Saturn. References [1] Richardson, J.D. and E. C. Sittler Jr., (1986) JGR, 91, 1381-1389. [2] Mauk, B. H. et al., (2005) GRL, 32, L14S05.

Müller, A. L.; Saur, J.; Krupp, N.; Mitchell, D. G.; Krimigis, S. M.; Roussos, E.

2008-09-01

83

TonB-dependent transporters: regulation, structure, and function  

PubMed Central

TonB-dependent transporters (TBDTs) are bacterial outer membrane proteins that bind and transport ferric chelates called siderophores, as well as vitamin B12, nickel complexes, and carbohydrates. The transport process requires energy in the form of protonmotive force and a complex of three inner membrane proteins, TonB-ExbB-ExbD, to transduce this energy to the outer membrane. The siderophore substrates range in complexity from simple small molecules such as citrate to large proteins like serum transferrin and haemoglobin. Because iron uptake is vital for almost all bacteria, expression of TBDTs is regulated in a number of ways that include metal-dependent regulators, ?/anti-? factor systems, small RNAs, and even a riboswitch. In recent years many new structures of TBDTs have been solved in various states, resulting in a more complete picture of siderophore selectivity and binding, signal transduction across the outer membrane, and interaction with TonB-ExbB-ExbD. However, the transport mechanism is still unclear. In this review, we summarize recent progress in understanding regulation, structure and function in TBDTs and questions remaining to be answered.

Noinaj, Nicholas; Guillier, Maude; Barnard, Travis J.; Buchanan, Susan K.

2011-01-01

84

CFTR-Dependent Anion Transport in Airway Epithelia  

Microsoft Academic Search

\\u000a Vertebrates use a variety of anion transport systems to drive transepithelial fluid secretion, each regulated by distinct\\u000a second messenger systems. Tissues such as the pancreatic duct and colon respond to peptide hormones and transmitters that\\u000a elevate intracellular levels of cAMP or cGMP (see Chap. 9 by J. F. White, this volume), whereas most exocrine glands have\\u000a a dominant calcium-dependent system,

J. W. Hanrahan

85

Engineering interband transport by time-dependent disorder  

SciTech Connect

We show how the evolution of atoms in a tilted lattice can be changed and controlled by phase noise on the lattice. Dependent on the characteristic parameters of the noise, the interband transport can be either suppressed or enhanced, which is of interest for very precise control in experiments with Bose-Einstein condensates. The effect of the noise on the survival probability in the ground band is summarized in a scaling plot, stressing the universality of our results.

Tayebirad, Ghazal [Institut fuer Theoretische Physik, Universitaet Heidelberg, Philosophenweg 19, D-69120 Heidelberg (Germany); Mannella, Riccardo [Dipartimento di Fisica ''E. Fermi,'' Universita di Pisa, Largo Pontecorvo 3, I-56127 Pisa (Italy); Wimberger, Sandro [Institut fuer Theoretische Physik, Universitaet Heidelberg, Philosophenweg 19, D-69120 Heidelberg (Germany); Heidelberg Center for Quantum Dynamics, Philosophenweg 12, D-69120 Heidelberg (Germany)

2011-09-15

86

Sodium-dependent ascorbic acid transporter family SLC23  

Microsoft Academic Search

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

Hitomi Takanaga; Bryan Mackenzie; Matthias A. Hediger

2004-01-01

87

Neurofilament Transport Is Dependent on Actin and Myosin  

Microsoft Academic Search

Real-time analyses have revealed that some newly synthesized neurofilament (NF) subunits translocate into and along axonal neurites by moving along the inner plasma membrane surface, suggesting that they may translocate against the submembrane actin cortex. We therefore examined whether or not NF axonal transport was dependent on actin and myosin. Perturbation of filamentous actin in NB2a\\/d1 cells with cytochalasin B

Cheolwha Jung; Teresa M. Chylinski; Aurea Pimenta; Daniela Ortiz; Thomas B. Shea

2004-01-01

88

Molecular spintronics: spin-dependent electron transport in molecular wires  

Microsoft Academic Search

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

Eldon G. Emberly; George Kirczenow

2002-01-01

89

Glucose-dependent Insulinotropic Polypeptide (GIP) Stimulates Transepithelial Glucose Transport  

Microsoft Academic Search

The purpose of this study was to characterize the effects of glucose-dependent insulinotropic peptide (GIP) on small intestinal glucose transport in vitro. Stripped proximal jejunum from fasted mice was mounted in Ussing chambers. The serosal side was bathed in Regular Ringer solution containing 5 mmol\\/l glucose, and the mucosal side, with solution containing 10 mmol\\/l 3-O-methyl glucose (3OMG). Intercellular cyclic

Satish K. Singh; Aaron C. Bartoo; Selvi Krishnan; Michael O. Boylan; John H. Schwartz; M. Michael Wolfe

2008-01-01

90

Heliostat tilt and azimuth angle charts and the heliostat orientation protractor  

Microsoft Academic Search

This paper reports that using cartesian heliostat field coordinates analytical expressions were derived for the heliostat tilt angle s, and heliostat azimuth angle γ (clockwise from south). These expressions are dependent on the field cartesian coordinates of the center of the heliostat and the solar zenith and azimuth angles (clockwise from south), θ{sub z} and Ψ, respectively. Here, cylindrical coordinates

M. M. Elsayed; O. M. Al-Rabghi

1992-01-01

91

Moisture dependence of radon transport in concrete: measurements and modeling.  

PubMed

The moisture dependence of the radon-release rate of concrete was measured under well controlled conditions. It was found that the radon-release rate almost linearly increases up to moisture contents of 50 to 60%. At 70 to 80% a maximum was found and for higher moisture contents the radon-release rate decreases very steeply. It is demonstrated that this dependence can be successfully modeled on basis of the multi-phase radon-transport equation in which values for various input parameters (porosity, diffusion coefficient, emanation factor, etc.) were obtained from independent measurements. Furthermore, a concrete structure development model was used to predict at any moment in time the values of input parameters that depend on the evolution of the concrete microstructure. Information on the concrete manufacturing recipe and curing conditions (temperature, relative humidity) was used as input for the concrete structure model. The combined radon transport and concrete structure model supplied sufficient information to assess the influence of relative humidity on the radon source and barrier aspects of concrete. More specifically, the model has been applied to estimate the relative contributions to the radon exhalation rate of a 20-cm-thick concrete slab of radon produced in the concrete slab itself and due to diffusive transport through the slab of radon from soil gas. PMID:13678285

Cozmuta, I; van der Graaf, E R; de Meijer, R J

2003-10-01

92

Transport and Separatrices in Time-Dependent Flows  

NASA Astrophysics Data System (ADS)

The method of using Finite Time Liapunov Exponents (FTLE) to extract Lagrangian Coherent Structures (LCS) in aperiodic flows, as originally developed by Haller, is applied to geophysical flows, and flows in the phase space of second order dynamical systems. In this approach, the LCS are identified as surfaces of greatest separation that parse the flow into regions with different dynamical behavior. In this way, the LCS reveal the underlying skeleton of turbulence. The time-dependence of the LCS provides insight into the mechanisms by which fluid is transported from one region to another. Of especial interest in this study, is the utility with which the FTLE-LCS method can be used to reveal homoclinic and horseshoe dynamics in aperiodic flows. The FTLE-LCS method is applied to turbulent flow in hurricanes and reveals LCS that delineate sharp boundaries to a storm. Moreover, intersections of the LCS define lobes that mediate transport into and out of a storm through the action of homoclinic lobe dynamics. Using FTLE-LCS, the same homoclinic structures are seen to be a dominant transport mechanism in the Global Ocean, and provide insights into the role of mesoscale eddies in enhancing lateral mixing. Beyond geophysical flows, we also study transport in the phase space of a coupled oscillator model for biomolecules. Before we can analyze transport in this model, we first introduce an appropriate model reduction that captures the relevant statistics of the full system. In the reduced model, we see that transport is again mediated by the process of horseshoe dynamics in a perturbed homoclinic tangle. We also consider some theoretical aspects of FTLE-LCS, including the relationship between LCS and stable/unstable manifolds, the invariance of LCS, and the possibility of an evolution equation describing the motion of the LCS. A parallelized software for computing FTLE is also introduced.

Du Toit, Philip C.

93

Topographic Maps III: Back Azimuths and Triangulation  

NSDL National Science Digital Library

In this activity, students will learn the more advanced mapping skills of calculating back azimuths and triangulation. Using a local 7.5-minute series map, the teacher will select a starting point and an obstacle, have students follow an azimuth that leads them to the obstacle, let them construct a back azimuth and navigate around the obstacle while recording directions and distances. A number of viable solutions usually exist and can form the basis of a class discussion. For the triangulation portion of the exercise, the teacher will select and give grid coordinates for three points on the map and list the azimuths to be followed in the construction of a line through each point. Students will construct an azimuth-back azimuth line through each point until each end of the line hits a map margin. They will then record the coordinates and identify the object located at the intersection point of the three lines.

2012-08-16

94

Spin Dependent Transport in Graphene Nano Ribbon Devices  

NASA Astrophysics Data System (ADS)

Graphene is now one of the promising materials for future nanoelectronics. Especially graphene nanoribbon is attracting great attention since it possesses finite bandgap opening depending on the ribbon width and the transport orientation with respect to the graphene lattice. Another interesting property seen in graphene nanoribbon is the appearance of the ``edge-spin'' polarization at the edges of the zigzag-edged graphene nanoribbon. Recently it has been shown that such edge- spin polarization can be electrically controlled to induce the half-metallic band structure in such structures, meaning the electrical controllability of the spin current in such material. Therefore, toward the realization of the graphene nanoribbon spintronics, it is now important to study the spin- dependent transport characteristics in realistic device structure based on zigzag graphene nanoribbon. Here we present our numerical study of spin transport in zigzag-edged graphene nanoribbon transistor structures [1] using spin-density functional tight-binding method. Special attention is paid to the influence of edge roughness and electrostatic doping on the spin polarization and the spin current. [1] S.Souma, M.Ogawa, T.Yamamoto, K.Watanabe, J.Comp. Electron. 7, 390 (2008).

Souma, Satofumi; Ogawa, Matsuto; Yamamoto, Takahiro; Watanabe, Kazuyuki

2009-03-01

95

ELECTRON-TRANSPORT COMPONENTS OF STREPTOMYCIN-DEPENDENT ESCHERICHIA COLI  

PubMed Central

Bragg, P. D. (University of British Columbia, Vancouver, B. C, Canada) and W. J. Polglase. Electron-transport components of streptomycin-dependent Escherichia coli. J. Bacteriol. 86:544–547. 1963.—When a streptomycin-dependent strain of Escherichia coli was grown in antibiotic-free medium, the resulting streptomycin-depleted cells were found to contain relatively large amounts of vitamin K2. Cytochromes a1 and a2 were absent from depleted cells, and these cells metabolized glucose with the accumulation of lactic acid. Depleted cells were normal in their content of coenzyme Q8, total flavine, and cytochrome b. Growth of depleted cells on medium containing dihydrostreptomycin restored their ability to metabolize lactic acid concomitantly with a decrease in vitamin K2 to a normal level, and with the formation of cytochromes a1 and a2. It is concluded that streptomycin (or dihydrostreptomycin) is required by dependent E. coli for maintenance of the integrity of the electron-transport system.

Bragg, P. D.; Polglase, W. J.

1963-01-01

96

Activity-Dependent Regulation of Surface Glucose Transporter-3  

PubMed Central

Glucose transporter 3 (GLUT3) is the main facilitative glucose transporter in neurons. Glucose provides neurons with a critical energy source for neuronal activity. However, the mechanism by which neuronal activity controls glucose influx via GLUT3 is unknown. We investigated the influence of synaptic stimulation on GLUT3 surface expression and glucose import in primary cultured cortical and hippocampal neurons. Synaptic activity increased surface expression of GLUT3 leading to an elevation of intracellular glucose. The effect was blocked by N-Methyl-D-Aspartate receptor (NMDAR) and neuronal nitric oxide synthase (nNOS) inhibition. The Akt Inhibitor, Akt-I blocked NMDAR-induced GLUT3 surface expression while a nNOS-phosphomimetic mutant (S1412D) enhanced GLUT3 expression at cell surface. These results suggest that NMDAR/Akt-dependent nNOS phosphorylation is coupled to GLUT3 trafficking. We demonstrated that activation of cGMP-dependent protein kinase (cGK) increased the surface expression of GLUT3, which was repressed by Rp-8-pCPT-cGMPS, a potent cell permeable inhibitor of cGKs. These studies characterize the molecular basis for activity dependent increases in surface GLUT3 after stimulation of the NMDARs. NMDAR-induced increase in surface GLUT3 represents a novel pathway for control of energy supply during neuronal activity that is critical for maintaining glucose homeostasis during neuronal transmission.

Ferreira, Jainne M.; Burnett, Arthur L.; Rameau, Gerald A.

2011-01-01

97

Time-dependent transport-equation solver. Master's thesis  

SciTech Connect

A new time dependent neutron and photon transport code was developed. The code, FMP2DT (Finite element, Multigroup, P sub n, 2-Dimensional, Time dependent), was discretized in space using finite elements, discretized in energy using a multigroup approximation, and discretized in time using Euler' backward differencing scheme. Its angular flux dependency was discretized using spherical harmonics. A P sub 1 angular flux approximation allows some modeling of both anisotropic flux behavior and wave behavior. FMP2DT can model radiation transport in XZ slab or RZ cylindrical geometry. An inherently stable iteration solution scheme, an incomplete Cholesky conjugate gradient algorithm, calculates the total flux coefficients. FMP2DT was benchmarked against exact flux calculations in infinite XZ and RZ geometries. Two problems were solved by FMP2DT which involved the observation of the flux decay after injection of an inhomogeneous pulsed source to the configurations. A nuclear reactor, initially critical, had a pulsed source introduced at its center. This is typically done in so called Rossi-alpha experiments. FMP2DT showed that time must be allowed so that only the fundamental mode is dominant or the flux data will not yield credible information to calculate alpha. A uranium borehole problem was solved where FMP2DT showed that a counting instrument must be calibrated for different distances from a pulsed source because the flux decays with a different decay constant for each spatial point. Previous models did not account for this diffusion effect.

Lee, L.W.

1991-05-01

98

Influences of electron spin ordering on spin dependent transport  

NASA Astrophysics Data System (ADS)

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.

Miao, Guo-Xing

99

Spin dependent transport behavior in small world networks  

NASA Astrophysics Data System (ADS)

Density functional theory (DFT) combined with the non equilibrium Green's function formalism (NEGF) is applied to perform spin polarized transport calculations on small world network (SWN) systems consisting of atomic wires. Including the spin property in SWN structures leads to interesting electrical properties. It is revealed that the emerging spin polarization depends mainly on the SWN geometry given by the asymmetric distribution of loops joining the arbitrary atoms on the main chain. The spin-asymmetric behavior which yields the spin polarization is found to be largely determined by those loops which are close to the electrodes. However, spin polarization may vanish for a specific SWN structure due to symmetry.

Caliskan, S.; Canturk, M.

2012-09-01

100

Directional drilling azimuth control system  

SciTech Connect

A downhole anchor assembly is described for absorbing reaction torque from a downhole mud motor in a directional drill string so as to minimize azimuthal deviation from such reaction torque, the anchor assembly comprising: an elongated, generally cylindrical housing having upper and lower ends with tool joints thereon for coupling the body into a directional drill string and having a drilling fluid passage extending longitudinally through its length; at least one elongated chain support body longitudinally mounted in the housing; an elongated, endless anchor chain supported on the body, the chain having an elongated portion thereof longitudinally arranged and generally radially exposed externally of the body, the exposed chain portion being freely longitudinally movable along the body; the body being generally radially shiftable between a retracted position in which the exposed chain portion is substantially recessed in the housing; and actuating means in the housing engageable with the body for shifting the body from the retracted position to its extended position.

Cheek, A.E.

1986-09-23

101

Heat generation and transport due to time-dependent forces.  

PubMed

We study heat generation and transport properties for solids in the presence of arbitrary time-dependent forces. Using a nonequilibrium Green's function (NEGF) approach we present an exact analytical expression of heat current for the linear system. We found that the current can be expressed in terms of the displacement of the atoms in the center and the self-energy of the heat bath. We carry out the calculation for a periodic driving force and study the dependence of steady state current on frequency and system size for one- and two-dimensional systems. We obtain an explicit solution of current for a one-dimensional linear chain connected with a Rubin bath. We found that the heat current is related to the density of states of the system and is independent of the bath temperature in ballistic transport. The baths can absorb energy only when the external frequency lies within the phonon band frequency. We also discuss the effect due to nonlinear interactions in the center. PMID:22181095

Agarwalla, Bijay Kumar; Wang, Jian-Sheng; Li, Baowen

2011-10-12

102

Heat generation and transport due to time-dependent forces  

NASA Astrophysics Data System (ADS)

We study heat generation and transport properties for solids in the presence of arbitrary time-dependent forces. Using a nonequilibrium Green’s function (NEGF) approach we present an exact analytical expression of heat current for the linear system. We found that the current can be expressed in terms of the displacement of the atoms in the center and the self-energy of the heat bath. We carry out the calculation for a periodic driving force and study the dependence of steady state current on frequency and system size for one- and two-dimensional systems. We obtain an explicit solution of current for a one-dimensional linear chain connected with a Rubin bath. We found that the heat current is related to the density of states of the system and is independent of the bath temperature in ballistic transport. The baths can absorb energy only when the external frequency lies within the phonon band frequency. We also discuss the effect due to nonlinear interactions in the center.

Agarwalla, Bijay Kumar; Wang, Jian-Sheng; Li, Baowen

2011-10-01

103

Global Azimuthal Anisotropy in the Transition Zone  

Microsoft Academic Search

Surface wave dispersion measurements for Love wave overtones carry evidence of azimuthal anisotropy in the transition zone of Earth's mantle (400 to 660 kilometers deep). A Backus-Gilbert inversion of anisotropic phase velocity maps, with resolution kernels mainly sensitive to the transition zone, shows a robust long-wavelength azimuthally anisotropic velocity structure. This observation puts new constraints on the mineralogy and dynamics

Jeannot Trampert; Hendrik Jan van Heijst

2002-01-01

104

Azimuthal asymmetry in semi-inclusive deep inelastic scattering off nuclei as probe for q^  

NASA Astrophysics Data System (ADS)

The energy loss parameter q^ is one of the fundamental transport parameters of hadronic matter. Using the twist-4 collinear approach, we show that the cos?? azimuthal asymmetry in unpolarized semi-inclusive deeply inelastic scattering off a large nucleus at intermediate transverse momentum is a sensitive observable for its determination. The effect is due to the suppression of the azimuthal asymmetry by final-state multiple scattering.

Gao, Jian-Hua; Schäfer, Andreas; Zhou, Jian

2012-04-01

105

“Magnifying-Glass” Azimuthal Map Projections  

USGS Publications Warehouse

For maps focusing on a region of interest, but including surrounding areas to provide a setting, new azimuthal projections have been developed with a 'magnifying-glass' effect. On two such projections, inside a circle bounding the region of interest is a standard Azimuthal Equidistant or Lambert Azimuthal Equal-Area projection. Between this circle and an outer bounding circle azimuths remain true and the radial or area scale, respectively, remains constant, but at a reduced value. On four other projections, the inner portion is a standard azimuthal projection, which may be Stereographic, Gnomonic, or the above, but beyond this portion, the radial scale is gradually reduced to zero. Equivalents with rectangular boundaries are also available.

Snyder, John, P.

1987-01-01

106

Transport lattice models of heat transport in skin with spatially heterogeneous, temperature-dependent perfusion  

PubMed Central

Background Investigation of bioheat transfer problems requires the evaluation of temporal and spatial distributions of temperature. This class of problems has been traditionally addressed using the Pennes bioheat equation. Transport of heat by conduction, and by temperature-dependent, spatially heterogeneous blood perfusion is modeled here using a transport lattice approach. Methods We represent heat transport processes by using a lattice that represents the Pennes bioheat equation in perfused tissues, and diffusion in nonperfused regions. The three layer skin model has a nonperfused viable epidermis, and deeper regions of dermis and subcutaneous tissue with perfusion that is constant or temperature-dependent. Two cases are considered: (1) surface contact heating and (2) spatially distributed heating. The model is relevant to the prediction of the transient and steady state temperature rise for different methods of power deposition within the skin. Accumulated thermal damage is estimated by using an Arrhenius type rate equation at locations where viable tissue temperature exceeds 42°C. Prediction of spatial temperature distributions is also illustrated with a two-dimensional model of skin created from a histological image. Results The transport lattice approach was validated by comparison with an analytical solution for a slab with homogeneous thermal properties and spatially distributed uniform sink held at constant temperatures at the ends. For typical transcutaneous blood gas sensing conditions the estimated damage is small, even with prolonged skin contact to a 45°C surface. Spatial heterogeneity in skin thermal properties leads to a non-uniform temperature distribution during a 10 GHz electromagnetic field exposure. A realistic two-dimensional model of the skin shows that tissue heterogeneity does not lead to a significant local temperature increase when heated by a hot wire tip. Conclusions The heat transport system model of the skin was solved by exploiting the mathematical analogy between local thermal models and local electrical (charge transport) models, thereby allowing robust, circuit simulation software to obtain solutions to Kirchhoff's laws for the system model. Transport lattices allow systematic introduction of realistic geometry and spatially heterogeneous heat transport mechanisms. Local representations for both simple, passive functions and more complex local models can be easily and intuitively included into the system model of a tissue.

Gowrishankar, TR; Stewart, Donald A; Martin, Gregory T; Weaver, James C

2004-01-01

107

Relative azimuth inversion by way of damped maximum correlation estimates  

USGS Publications Warehouse

Horizontal seismic data are utilized in a large number of Earth studies. Such work depends on the published orientations of the sensitive axes of seismic sensors relative to true North. These orientations can be estimated using a number of different techniques: SensOrLoc (Sensitivity, Orientation and Location), comparison to synthetics (Ekstrom and Busby, 2008), or by way of magnetic compass. Current methods for finding relative station azimuths are unable to do so with arbitrary precision quickly because of limitations in the algorithms (e.g. grid search methods). Furthermore, in order to determine instrument orientations during station visits, it is critical that any analysis software be easily run on a large number of different computer platforms and the results be obtained quickly while on site. We developed a new technique for estimating relative sensor azimuths by inverting for the orientation with the maximum correlation to a reference instrument, using a non-linear parameter estimation routine. By making use of overlapping windows, we are able to make multiple azimuth estimates, which helps to identify the confidence of our azimuth estimate, even when the signal-to-noise ratio (SNR) is low. Finally, our algorithm has been written as a stand-alone, platform independent, Java software package with a graphical user interface for reading and selecting data segments to be analyzed.

Ringler, A.T.; Edwards, J.D.; Hutt, C.R.; Shelly, F.

2012-01-01

108

Density Dependence of Transport Coefficients from Holographic Hydrodynamics  

NASA Astrophysics Data System (ADS)

We study the transport coefficients of Quark-Gluon-Plasma in finite temperature and finite baryon density. We consider AdS/QCD of charged AdS black hole background with bulk-filling branes identifying the U(1) charge as the baryon number. Using Reissner-Nordström-AdS background, Green functions are explicitly obtained. We calculate the diffusion constant, the shear viscosity and the thermal conductivity, and plot their density and temperature dependences. Hydrodynamic relations between those are shown to hold exactly. The diffusion constant and the shear viscosity are decreasing as a function of density for fixed total energy. For fixed temperature, the fluid becomes less diffusible and more viscous for larger baryon density.

Ge, X.; Matsuo, Y.; Shu, F.; Sin, S.; Tsukioka, T.

2008-11-01

109

Azimuthal Anisotropy of pi0 Production in Au+Au Collisions at sNN=200GeV: Path-Length Dependence of Jet Quenching and the Role of Initial Geometry  

Microsoft Academic Search

We have measured the azimuthal anisotropy of pi0 production for 1

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. Csörgo; 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 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; J. Hanks; R. Han; E. P. Hartouni; E. Haslum; R. Hayano; M. Heffner; S. Hegyi; T. K. Hemmick; T. Hester; X. He; 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. 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. B. Lee; K. S. Lee; M. J. Leitch; M. A. L. Leite; E. Leitner; B. Lenzi; P. Liebing; L. A. Linden Levy; T. Liska; A. Litvinenko; H. Liu; M. X. Liu; X. Li; 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. Mikes; 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; R. Nouicer; A. S. Nyanin; E. O'Brien; S. X. Oda; C. A. Ogilvie; K. Okada; M. Oka; Y. Onuki; A. Oskarsson; M. Ouchida; K. Ozawa; R. Pak; V. Pantuev; V. Papavassiliou; I. H. 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. Ruzicka; 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. Slunecka; 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; M. Togawa; A. Toia; L. Tomásek; 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; G. R. Young; I. Younus; Z. You; I. E. Yushmanov; W. A. Zajc; C. Zhang; S. Zhou; L. Zolin

2010-01-01

110

Spin-dependent quantum transport in nanoscaled geometries  

NASA Astrophysics Data System (ADS)

We discuss experiments where the spin degree of freedom leads to quantum interference phenomena in the solid-state. Under spin-orbit interactions (SOI), spin rotation modifies weak-localization to weak anti-localization (WAL). WAL's sensitivity to spin- and phase coherence leads to its use in determining the spin coherence lengths Ls in materials, of importance moreover in spintronics. Using WAL we measure the dependence of Ls on the wire width w in narrow nanolithographic ballistic InSb wires, ballistic InAs wires, and diffusive Bi wires with surface states with Rashba-like SOI. In all three systems we find that Ls increases with decreasing w. While theory predicts the increase for diffusive wires with linear (Rashba) SOI, we experimentally conclude that the increase in Ls under dimensional confinement may be more universal, with consequences for various applications. Further, in mesoscopic ring geometries on an InAs/AlGaSb 2D electron system (2DES) we observe both Aharonov-Bohm oscillations due to spatial quantum interference, and Altshuler-Aronov-Spivak oscillations due to time-reversed paths. A transport formalism describing quantum coherent networks including ballistic transport and SOI allows a comparison of spin- and phase coherence lengths extracted for such spatial- and temporal-loop quantum interference phenomena. We further applied WAL to study the magnetic interactions between a 2DES at the surface of InAs and local magnetic moments on the surface from rare earth (RE) ions (Gd3+, Ho3+, and Sm3+). The magnetic spin-flip rate carries information about magnetic interactions. Results indicate that the heavy RE ions increase the SOI scattering rate and the spin-flip rate, the latter indicating magnetic interactions. Moreover Ho3+ on InAs yields a spin-flip rate with an unusual power 1/2 temperature dependence, possibly characteristic of a Kondo system. We acknowledge funding from DOE (DE-FG02-08ER46532).

Heremans, Jean J.

2011-10-01

111

Oil Dependence: Is Transport Running out of Affordable Fuel?  

Microsoft Academic Search

The transport sector’s demand for oil is less price sensitive than any other part of the economy. This is partly because demand for transport services is relatively insensitive to price and partly because substitutes for oil in road transport are currently far from cost-effective. Evidence from the USA suggests that as incomes rise, transport sector oil demand becomes even less

2008-01-01

112

The azimuth moveout operator for vertically inhomogeneous media  

Microsoft Academic Search

The azimuth moveout (AMO) operator, unlike the DMO operator, has a 3-D structure in homogeneous isotropic media, with an out-of-plane (crossline) com- ponent. In general, this component is concaved downward giving the operator an overall skewed-saddle shape. The AMO operator is typically smaller in size than conventional DMO operators. When velocity varies vertically, the operator shape changes depending on how

Tariq Alkhalifah; Biondo L. Biondi

113

Azimuthal and zenithal anchoring of nematic liquid crystals  

Microsoft Academic Search

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

Mojca Vilfan; Martin Copic

2003-01-01

114

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

NSDL National Science Digital Library

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.

PhD Hannelore Daniel (Technical University of Munich Dept of Nut'l Scis-Ernaehrungs-Physiol); Britta Spanier (Technical University of Munich Department of Food and Nutrition); Gabor Kottra (Technical University of Munich Department of Food and Nutrition); Dietmar Weitz (Technical University of Munich Department of Food and Nutrition)

2006-04-01

115

Concentration dependent transport of colloids in saturated porous media.  

PubMed

A series of column experiments was undertaken to explore the influence of colloid input concentration (2, 1, 0.5, and 0.25 times a reference concentration), colloid size (negatively charged 3.2 and 1.0 microm carboxyl latex), and sand grain size (360, 240, and 150 microm quartz sands) on transport and deposition. A similar mass of stable mono-dispersed colloids was added to each column. For a given input concentration, decreasing the sand size and increasing the colloid size resulted in increased mass retention in the sand near the column inlet and lower relative concentrations in the effluent. For a given sand and colloid, increasing the input concentration produced less deposition and higher mass recovery in the effluent, especially for coarser sands and smaller colloids. Results of a time dependent attachment (blocking) and detachment model were not consistent with this behavior because the simulations predicted much less retention near the column inlet and a decreasing number of favorable attachment sites (mass of deposited colloids) with increasing input concentration in a given system (colloid and sand). A time dependent straining model (filling of straining sites) provided a better description of the effluent and deposition data, but still could not account for the observed concentration dependent mass recovery. Alternatively, the straining model was refined to include a liberation term that assumed that straining was hindered at higher concentrations (collision frequencies) due to repulsive colloid (aqueous phase)-colloid (strained) interactions. Simulations that included straining, liberation, attachment, and detachment significantly improved the description of the experimental data. PMID:16290313

Bradford, Scott A; Bettahar, Mehdi

2005-11-14

116

Heliostat tilt and azimuth angle charts and the heliostat orientation protractor  

SciTech Connect

This paper reports that using cartesian heliostat field coordinates analytical expressions were derived for the heliostat tilt angle s, and heliostat azimuth angle {gamma} (clockwise from south). These expressions are dependent on the field cartesian coordinates of the center of the heliostat and the solar zenith and azimuth angles (clockwise from south), {theta}{sub z} and {Psi}, respectively. Here, cylindrical coordinates are conveniently used to derive the expressions for the heliostat angles s and {gamma}. The expression of {gamma}is used to construct the so-called heliostat orientation protractor. The protractor is a useful tool to determine the instantaneous heliostat azimuth angle as will be illustrated.

Elsayed, M.M.; Al-Rabghi, O.M. (Thermal Energy Dept., King Abdulaziz Univ., Jeddah 21413 (SA))

1992-02-01

117

A Modified Direct-Reading Azimuth Protractor  

ERIC Educational Resources Information Center

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)

Larson, William C.; Pugliese, Joseph M.

1977-01-01

118

Regions of azimuthal instability in gyrotrons  

SciTech Connect

This paper is devoted to the analysis of the instability of operating modes in high-power gyrotrons with cylindrically symmetric resonators. This instability manifests itself in destruction of the azimuthally uniform wave envelope rotating in a gyrotron resonator having a transverse size greatly exceeding the wavelength. The appearance of azimuthally nonuniform solutions can be interpreted as simultaneous excitation of modes with different azimuthal indices. This problem is studied self-consistently, i.e., taking into account the temporal evolution of both the azimuthal and axial structures of the wave envelope. The region of gyrotron operation free from this instability is identified. The efficiency achievable in this region can be only 1%-2% lower than the maximum efficiency. It is also possible to address the difference between the theory of mode interaction developed under assumption that all modes have fixed axial structure and the self-consistent theory presented here. As known, for fixed axial mode profiles, single-mode high-efficiency oscillations remain stable no matter how dense is the spectrum of competing modes, while the self-consistent theory predicts stable high-efficiency operation only when the azimuthal index does not exceed a certain critical value. It is shown that the azimuthal instability found in the self-consistent theory is caused by excitation of modes having axial structures different from that of the desired central mode.

Dumbrajs, O. [Institute of Solid State Physics, University of Latvia, Kengaraga Street 8, LV-1063 Riga (Latvia); Nusinovich, G. S.; Antonsen, T. M. Jr. [Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, Maryland 20742-3511 (United States)

2012-06-15

119

Time dependent transport simulations of JET H mode plasmas  

Microsoft Academic Search

A drift wave based transport model is used to self-consistently predict the time evolution of temperature and density profiles in JET H mode tokamak discharges. It is found that the same theoretically derived gyro-Bohm transport model previously used to simulate systematic scans of L mode discharges is equally successful in modelling JET ELMy H mode plasmas, implying that core transport

J. E. Kinsey

1999-01-01

120

TEMPERATURE DEPENDENCE OF THE NEUTRON TRANSPORT CROSS SECTION IN PARAFFIN AND POLYETHYLENE  

Microsoft Academic Search

For presentation at Colloquium at R.P.I., February 15, A semi-empirical ; prescription describing the temperature dependence of the neutron transport cross ; section is presented, along with an experimental determination of the same ; quantity. In the prescription, an energy dependent transport cross section is ; calculated from the energy dependent-reduced mass of the scattering center as ob ; tained

Esch

1962-01-01

121

Azimuthal asymmetries in deep inelastic e+p {yields} e+X scattering at HERA  

SciTech Connect

A Monte Carlo study of the azimuthal angular distribution around the virtual boson-proton beam axis at HERA is presented. In the presence of typical acceptance and selection criteria in the laboratory frame the azimuthal distribution is investigated for different kinematical variables. The best measurable dependence of and is found to be for rapidity Y or pseudorapidity {eta} using the energy flow method.

Tymieniecka, Teresa [Warsaw University, Warsaw (Poland)

2005-10-06

122

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

PubMed Central

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.

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

2010-01-01

123

Contaminant transport in soil with depth-dependent reaction coefficients and time-dependent boundary conditions.  

PubMed

Predicting the fate and movement of contaminant in soils and groundwater is essential to assess and reduce the risk of soil contamination and groundwater pollution. Reaction processes of contaminant often decreased monotonously with depth. Time-dependent input sources usually occurred at the inlet of natural or human-made system such as radioactive waste disposal site. This study presented a one-dimensional convection-dispersion equation (CDE) for contaminant transport in soils with depth-dependent reaction coefficients and time-dependent inlet boundary conditions, and derived its analytical solution. The adsorption coefficient and degradation rate were represented as sigmoidal functions of soil depth. Solute breakthrough curves (BTCs) and concentration profiles obtained from CDE with depth-dependent and constant reaction coefficients were compared, and a constant effective reaction coefficient, which was calculated by arithmetically averaging the depth-dependent reaction coefficient, was proposed to reflect the lumped depth-dependent reaction effect. With the effective adsorption coefficient and degradation rate, CDE could produce similar BTCs and concentration profiles as those from CDE with depth-dependent reactions in soils with moderate chemical heterogeneity. In contrast, the predicted concentrations of CDE with fitted reaction coefficients at a certain depth departed significantly from those of CDE with depth-dependent reactions. Parametric analysis was performed to illustrate the effects of sinusoidally and exponentially decaying input functions on solute BTCs. The BTCs and concentration profiles obtained from the solutions for finite and semi-infinite domain were compared to investigate the effects of effluent boundary condition. The finite solution produced higher concentrations at the increasing limb of the BTCs and possessed a higher peak concentration than the semi-infinite solution which had a slightly long tail. Furthermore, the finite solution gave a higher concentration in the immediate vicinity of the exit boundary than the semi-infinite solution. The applicability of the proposed model was tested with a field herbicide and tracer leaching experiment in an agricultural area of northeastern Greece. The simulation results indicated that the proposed CDE with depth-dependent reaction coefficients was able to capture the evolution of metolachlor concentration at the upper soil depths. However, the simulation results at deep depths were not satisfactory as the proposed model did not account for preferential flow observed in the field. PMID:23490106

Gao, Guangyao; Fu, Bojie; Zhan, Hongbin; Ma, Ying

2013-02-26

124

Spin-dependent heat transport and thermal boundary resistance  

NASA Astrophysics Data System (ADS)

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

Jeong, Taehee

125

Temperature-dependent thermal transport properties of Archean rocks  

NASA Astrophysics Data System (ADS)

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.

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

2010-12-01

126

The mechanism of energy-dependent ion transport in mitochondria  

Microsoft Academic Search

Summary The transport of potassium, sodium and various anions in rat-liver mitochondria was studied mainly by analysis of ion content and water compartmentation of the mitochondrial pellet. A comparison of spontaneous transport with valinomycin- or gramicidin-stimulated transport is made. The rate or extent of uptake, the internal concentrations and the concentration ratio (Cin\\/Cout) are calculated and compared to test existing

Hagai Rottenberg

1973-01-01

127

Ionic dependence of amino-acid transport in the exocrine pancreatic epithelium: Calcium dependence of insulin action  

Microsoft Academic Search

Summary Rapid unidirectional transport (15 sec) ofl-serine and 2-methylaminoisobutyric acid (MeAIB) was studied in the isolated perfused rat pancreas using a dual-tracer dilution technique. Time-course experiments in the presence of normal cation gradients revealed a time-dependent transstimulation ofl-serine influx and transinhibition of MeAIB influx. Transport of the model nonmetabolized System A analog MeAIB was Na+ dependent and significantly inhibited during

P. S. R. Norman; G. E. Mann

1987-01-01

128

Free-space azimuthal paraxial wave equation: the azimuthal Bessel-Gauss beam solution  

Microsoft Academic Search

We develop a paraxial wave equation for an azimuthally polarized field propagating in free space. The equation's beamlike solution is composed of a plane-wave propagation factor multiplied by a Bessel function of the first kind, of order one, and a Gaussian factor, which describe the transverse characteristics of the beam. We compare the propagation characteristics of the azimuthal Bessel-Gauss beam

Rebecca H. Jordan; Dennis G. Hall

1994-01-01

129

Spin-dependent electron transport in nanoscale samples  

NASA Astrophysics Data System (ADS)

In this thesis, we describe the research in which we use metallic nanoparticles to explore spin-dependent electron transport at nanometer scale. Nanoscale samples were fabricated by using a state of the art electron beam lithography and shadow evaporation technique. We have investigated spin relaxation and decoherence in metallic grains as a function of bias voltage and magnetic field at low temperatures (down to ˜30mK). At low temperatures, the discrete energy levels within a metallic nanoparticle provides a new means to study the physics of the spin-polarized electron tunneling. We describe measurements of spin-polarized tunneling via discrete energy levels of single Aluminum grain. Spin polarized current saturates quickly as a function of bias voltage, which demonstrates that the ground state and the lowest excited states carry spin polarized current. The ratio of electron-spin relaxation time (T1) to the electron-phonon relaxation rate is in quantitative agreement with the Elliot-Yafet scaling, an evidence that spin-relaxation in Al grains is driven by the spin-orbit interaction. The spin-relaxation time of the low-lying excited states is T1 ? 0.7 mus and 0.1 mus in two samples, showing that electron spin in a metallic grain could be a potential candidate for quantum information research. We also present measurements of mesoscopic resistance fluctuations in cobalt nanoparticles at low temperature and study how the fluctuations with bias voltage, bias fingerprints, respond to magnetization-reversal processes. Bias fingerprints rearrange when domains are nucleated or annihilated. The domain wall causes an electron wave function-phase shift of ˜5 pi. The phase shift is not caused by the Aharonov-Bohm effect; we explain how it arises from the mistracking effect, where electron spins lag in orientation with respect to the moments inside the domain wall. The dephasing length at low temperatures is only 30 nm, which is attributed to the large magnetocrystalline anisotropy in Co.

Wei, Yaguang

130

Computation of synthetic seismograms for stratified azimuthally anisotropic media  

SciTech Connect

The authors outline a method of computing synthetic seismograms for stratified, azimuthally anisotropic, viscoelastic earth models. This method is an extended form of the Kennett algorithm that is efficient for multioffsett vertical seismic profiling. The model consists of a stack of homogeneous plane layers. In each layer, the 6 {times} 6 system matrix A is diagonalized numerically; this permits treatment of triclinic materials, i.e., those with the lowest possible symmetry. Jacobi iteration is an efficient way to diagonalize A because the entries of A change little from one wavenumber to the next. When the material properties are frequency dependent, the wavenumber loops are inside the frequency loop, and the computation is slow even on a supercomputer. When the material parameters are frequency independent, it is better to make frequency the deepest loop, with diagonalization of A outside the loop, in which case vectorization gives a relatively rapid computation. Temporal wraparound is avoided by making use of complex frequencies, and spatial aliasing is avoided by using a generalized Filon's method to evaluate both the wavenumber integrals. Various methods of generating anisotropic elastic constants from microlayers, cracks, and fractures and joints are discussed. Example computations are given for azimuthally isotropic and azimuthally anisotropic (AA) earth models. Comparison of computations using single and double wavenumber integrations for a realistic AA model shows that single wavenumber integration often gives incorrect answers especially at near offsets. Errors due to use of a single wavenumber integration are explained heuristically by use of wave front diagrams for point and line sources.

Mallick, S.; Frazer, L.N. (Univ. of Hawaii, Honolulu (United States))

1990-06-10

131

Meeting future transportation needs: can we break our oil dependence  

Microsoft Academic Search

Americans are returning to cars that consume more gasoline because of a short-term surplus of oil, but the world will have to develop completely new transportation fuels within a century. If the US wants to continue to rely on the automobile as its transportation mode, it must take immediate steps to increase automobile efficiency and to develop new fuels based

Bleviss

2009-01-01

132

Development of Na exp + -Dependent Hexose Transport in Vitro.  

National Technical Information Service (NTIS)

The desriptions given here of experiments with LLC-PK sub 1 cell transport systems are more of a progress report than a definitive statement. The cells give great promise for exploring the differentiation of an important transport system, but a number of ...

J. S. Cook K. Amsler E. R. Weiss C. Shaffer

1981-01-01

133

Azimuthal modulation of C-band scatterometer {sigma}{sup 0} over southern ocean sea ice  

SciTech Connect

In a continuing evaluation of the ERS-1 C-band scatterometer as a tool for studying polar sea ice, the authors evaluate the azimuthal modulation characteristics of Antarctic sea ice. ERS-1 AMI scatterometer mode data sets from several study regions dispersed in the Antarctic seasonal sea ice pack are evaluated for azimuthal modulation. When appropriate, the incidence angle dependence is estimated and removed in a study region before determining whether azimuthal modulation is present in the data. Other comparisons are made using the fore and aft beam measurement difference. The results show that over the ice pack, azimuthal modulation is less than 1 dB at the scale of observation of the ERS-1 C-band scatterometer.

Early, D.S.; Long, D.G. [Brigham Young Univ., Provo, UT (United States)

1997-09-01

134

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...

135

Emerging roles for sodium dependent amino acid transport in mesenchymal cells  

Microsoft Academic Search

The functional aspects of sodium dependent amino acid transport in mesenchymal cells are the subject of this contribution. In a survey of the cross-talk existing among the various transport mechanisms, particular attention is devoted to the role played by substrates shared by several transport systems, such as L-glutamine. Intracellular levels of glutamine are determined by the activity of System A,

V. Dall'Asta; R. Franchi-Gazzola; O. Bussolati; R. Sala; B. M. Rotoli; P. A. Rossi; J. Uggeri; S. Belletti; R. Visigalli; G. C. Gazzola

1996-01-01

136

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

PubMed

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 and 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

Razak, K A

2012-05-26

137

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

PubMed Central

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.

Razak, K.A.

2012-01-01

138

Glutamine transport in isolated epithelial intestinal cells. Identification of a Na + -dependent transport mechanism, highly specific for glutamine  

Microsoft Academic Search

L-Glutamine transport was evaluated in isolated cells from the guinea-pig small intestine by measuring [3H]-L-glutamine uptake. Villous and crypt cells expressed Na+-dependent and Na+-independent transport mechanisms. Glutamine transport systems were identified using various amino acids and analogues as inhibitors. In both villous and crypt cells, 2-(methylamino)-isobutyrate (MeAIB), a system A inhibitor, did not inhibit Na+-dependent glutamine influx. 2-Aminobicyclo(2,2,1)heptane-2-carboxylate (BCH), a

Jesffls R. del Castillo; María C. Súlbaran-Carrasco; Luis Burguillos

2002-01-01

139

Structural domains of chimeric dopamine-noradrenaline human transporters involved in the Na(+)- and Cl(-)-dependence of dopamine transport.  

PubMed

Catecholamine transporters constitute the biological targets for several important drugs, including antidepressants, cocaine, and related compounds. Some information exists about discrete domains of these transporters that are involved in substrate translocation and uptake blockade, but delineation of domains mediating the ionic dependence of the transport remains to be defined. In the present study, human neuronal transporters for dopamine and noradrenaline (hDAT and hNET) and a series of six functional chimeras were transiently expressed in LLC-PK1 cells. Substitution of Cl(-) by isethionate reveals that cassette IV (i.e., the region of the transporter encompassing transmembrane domain 9 through the COOH terminal) plays an important role in the Cl(-)- dependence of the uptake. Substitutions of Na(+) and NaCl by Tris(+) and sucrose, respectively, demonstrate that three different segments scattered across the transporter are involved in the Na(+)- dependence of the transport activity: cassette I (i.e., the region from the amino terminus through the first two transmembrane domains), cassette IV, and junction between transmembrane domains 3 to 5 and 6 to 8. Results of the present work also suggest that the use of Tris(+) as a substitute for Na(+) results in a biased estimate of the Hill number value for hDAT. This study provides useful clues for identifying specific residues involved in the uptake function of the catecholamine transporters. PMID:11093780

Syringas, M; Janin, F; Mezghanni, S; Giros, B; Costentin, J; Bonnet, J J

2000-12-01

140

Type 1 Sodium-dependent Phosphate Transporter (SLC17A1 Protein) Is a Cl?-dependent Urate Exporter*  

PubMed Central

SLC17A1 protein (NPT1) is the first identified member of the SLC17 phosphate transporter family and mediates the transmembrane cotransport of Na+/Pi in oocytes. Although this protein is believed to be a renal polyspecific anion exporter, its transport properties are not well characterized. Here, we show that proteoliposomes containing purified SLC17A1 transport various organic anions such as p-aminohippuric acid and acetylsalicylic acid (aspirin) in an inside positive membrane potential (??)-dependent manner. We found that NPT1 also transported urate. The uptake characteristics were similar to that of SLC17 members in its Cl? dependence and inhibitor sensitivity. When arginine 138, an essential amino acid residue for members of the SLC17 family such as the vesicular glutamate transporter, was specifically mutated to alanine, the resulting mutant protein was inactive in ??-dependent anion transport. Heterologously expressed and purified human NPT1 carrying the single nucleotide polymorphism mutation that is associated with increased risk of gout in humans exhibited 32% lower urate transport activity compared with the wild type protein. These results strongly suggested that NPT1 is a Cl?-dependent polyspecific anion exporter involved in urate excretion under physiological conditions.

Iharada, Masafumi; Miyaji, Takaaki; Fujimoto, Takahiro; Hiasa, Miki; Anzai, Naohiko; Omote, Hiroshi; Moriyama, Yoshinori

2010-01-01

141

Energization of Radiation Belt Electrons by High and Low Azimuthal Mode Number Poloidal Mode ULF Waves  

NASA Astrophysics Data System (ADS)

CME-shock and CIR-driven geomagnetic storms are characterized by enhanced ULF wave activity in the magnetosphere. This enhanced ULF wave power produces both coherent and diffusive transport and energization, as well as pitch angle modification of radiation belt electrons in drift resonance with azimuthally propagating ULF waves. Recent observations of two CME-driven storms1,2 have suggested that poloidal mode waves with both low and high azimuthal mode number may be efficient at accelerating radiation belt electrons. We extend up to m = 50 the analysis of Ozeke and Mann3 who examined drift resonance for poloidal modes up to m = 40. We calculate radial diffusion coefficients for source population electrons in the 50 -500 keV range, and continued resonance with lower m-numbers at higher energies for ULF waves in the Pc 5, 0.4 - 10 mHz range. We use an analytic model for ULF waves superimposed on a compressed dipole, developed for equatorial plane studies by Elkington et al.4 and extended to 3D by Perry et al.4 Assuming a power spectrum which varies as ?-2, consistent with earlier observations, we find greater efficiency for radial transport and acceleration at lower m number where there is greater power for drift resonance at a given frequency. This assumption is consistent with 3D global MHD simulations using the Lyon-Fedder-Mobarry code which we have carried out for realistic solar wind driving conditions during storms. Coherent interaction with ULF waves can also occur at a rate which exceeds nominal radial diffusion estimates but is slower than prompt injection on a drift time scale. Depending on initial electron drift phase, some electrons are accelerated due to the westward azimuthal electric field E?, while others are decelerated by eastward E?, decreasing their pitch angle. A subset of trapped electrons are seen to precipitate to the atmosphere in 3D LFM simulations, showing modulation at the coherent poloidal mode ULF wave frequency in both simulations and MINIS balloon observations for the January 21, 2005 CME-driven storm. Thus Pc 5 poloidal mode ULF waves cause competing increase and decrease in relativistic electron flux. The relative efficiencies of both coherent and diffusive processes will be examined. 1Zong et al., JGR, doi:10.1029/2009JA014393, 2009. 2Tan et al., JGR, doi:10.1029/2010JA016226, 2011. 3Ozeke and Mann, JGR, doi:10.1029/2007JA012468, 2008. 4Elkington et al., doi:10.1029/2001JA009202, 2003, 2003. 5Perry et al., doi:10.1029/2004JA010760, 2005.

Hudson, M. K.; Brito, T.; Elkington, S. R.; Kress, B. T.; Liang, Y.

2011-12-01

142

Global azimuthal anisotropy in the transition zone.  

PubMed

Surface wave dispersion measurements for Love wave overtones carry evidence of azimuthal anisotropy in the transition zone of Earth's mantle (400 to 660 kilometers deep). A Backus-Gilbert inversion of anisotropic phase velocity maps, with resolution kernels mainly sensitive to the transition zone, shows a robust long-wavelength azimuthally anisotropic velocity structure. This observation puts new constraints on the mineralogy and dynamics of the transition zone because this anisotropy may result from aligned minerals, tilted laminated structures, or even organized pockets of fluid inclusions. PMID:12016310

Trampert, Jeannot; van Heijst, Hendrik Jan

2002-05-17

143

Flux Method for the Field Dependent Transport through Multilayer Devices.  

National Technical Information Service (NTIS)

A flux method of treating the one dimensional steady state transport problem of excess charged carriers, created by the generating sources, is analyzed for the multilayer devices in the presence of a nonuniform electric field. General analytical expressio...

R. Kishore

1988-01-01

144

Two-particle azimuthal correlations at forward rapidity in STAR  

NASA Astrophysics Data System (ADS)

During the 2008 run the Relativistic Heavy Ion Collider (RHIC) at the Brookhaven Nation Laboratiory (BNL), NY, provided high luminosity in both p+p and d+Au collisions at sqrt{s_{NN}}=200 GeV. Electromagnetic calorimeter acceptance in STAR was enhanced by the new Forward Meson Spectrometer (FMS), and is now almost contiguous from -1azimuth. This allows measurements of the azimuthal correlation between a forward neutral pion and a second particle in a very large rapidity range. The associated particle can be either a mid-rapidity neutral pion (using the STAR Barrel Electromagnetic Calorimeter, BEMC), a mid-rapidity charged particle (using the STAR Time Projection Chamber, TPC) or a second forward neutral pion in the FMS. Di-hadron azimuthal correlations provide sensitivity to the low longitudinal momentum fraction (x) component of the gluon density in the nuclear target. Initial state nonlinear effects are in fact expected to appear in d+Au collisions when the dense part of the nucleus is probed. The analysis in this thesis shows that such correlations and their dependence on rapidity, transverse momentum and collision centrality are qualitative consistent with the existence of gluon saturation effects in the relativistic nucleus. Correlations between a forward pion and a mid-rapidity particle do not show any significant broadening in the correlated peak in going from p+p to d+Au interactions. On the contrary, when the two particle are both reconstructed in the forward region (where the lowest x value is probed), d+Au collisions present a significantly broader peak in the azimuthal correlation than in p+p. Such effect is stronger when the p_{T} of the associated particle is lower and when central collisions are selected. Theoretical expectations for azimuthal correlations between a dilute system (deuteron) and a saturated target (Gold nucleus) have been explored. Two different approaches (dipole model and k_{T} factorization) for calculating the coincidence probability within the Color Glass Condensate (CGC) framework show qualitative agreement with the measurement.

Braidot, E.

2011-01-01

145

Azimuth angle variations of specular reflection echoes in the lower atmosphere observed with the MU radar  

NASA Astrophysics Data System (ADS)

We studied azimuth angle variations of clear-air echoes in the troposphere and lower stratosphere, observed by steering the antenna beam of the MU radar into 12 positions, the azimuth angle being changed every 30° at a zenith angle of 6°. Azimuth angle variations of the echo intensity were recognized in a large height range in the lower stratosphere, although they were also sometimes found in the troposphere, which was approximated by a fairly smooth sinusoidal curve, with one or two cycles in 360° azimuth angle. Moreover, their structure showed continuous progression with time and altitude. The range of variations was generally greater in the lower stratosphere, the ratio of the maximum to the minimum sometimes exceeding 15 dB. The large azimuth angle variations were associated with the aspect sensitivity of the echo power, suggesting that they were caused by the characteristics of specular reflection rather than the effects of localized turbulence scattering, and suggesting that the reflection surface was corrugated, probably the result of the effects of gravity waves. A numerical model qualitatively explained the fundamental behavior of the azimuth angle dependence of the echo power, it being assumed that the vertical displacement of the reflection surface showed sinusoidal variation caused by the dynamical effects of a monochromatic gravity wave.

Tsuda, Toshitaka; Gordon, William E.; Saito, Hideya

1997-05-01

146

XPORT-dependent transport of TRP and rhodopsin.  

PubMed

TRP channels have emerged as key biological sensors in vision, taste, olfaction, hearing, and touch. Despite their importance, virtually nothing is known about the folding and transport of TRP channels during biosynthesis. Here, we identify XPORT (exit protein of rhodopsin and TRP) as a critical chaperone for TRP and its G protein-coupled receptor (GPCR), rhodopsin (Rh1). XPORT is a resident ER and secretory pathway protein that interacts with TRP and Rh1, as well as with Hsp27 and Hsp90. XPORT promotes the targeting of TRP to the membrane in Drosophila S2 cells, a finding that provides a critical first step toward solving a longstanding problem in the successful heterologous expression of TRP. Mutations in xport result in defective transport of TRP and Rh1, leading to retinal degeneration. Our results identify XPORT as a molecular chaperone and provide a mechanistic link between TRP channels and their GPCRs during biosynthesis and transport. PMID:22099462

Rosenbaum, Erica E; Brehm, Kimberley S; Vasiljevic, Eva; Liu, Che-Hsiung; Hardie, Roger C; Colley, Nansi Jo

2011-11-17

147

Development of Na/sup +/-dependent hexose transport in vitro  

SciTech Connect

The desriptions given here of experiments with LLC-PK/sub 1/ cell transport systems are more of a progress report than a definitive statement. The cells give great promise for exploring the differentiation of an important transport system, but a number of cell biological problems need resolution first. The kinetic analysis described suggests that the individual cells become fully, possibly terminally, differentiated and remain so. It is equally desirable to have a means of separating differentiated from undifferentiated cells, and to know the transport capacity of each. With these questions resolved, the use of modulators of the rate of differentiation, acceleration by inducers and inhibition by tumor promoters, gives obviously important experimental handles in exploring the underlying processes. The clones that have been derived so far add another dimension to the possibilities of this cell system, since the clones show different responses to the inducers and to TPA and these differences will be of value in sorting out mechanisms.

Cook, J.S.; Amsler, K.; Weiss, E.R.; Shaffer, C.

1981-01-01

148

Azimuthal Correlations in p-p collisions  

SciTech Connect

We report the analysis of experimental azimuthal correlations measured by STAR in p-p collisions at {radical}(s{sub NN}) = 200 GeV. We conclude that for a fit of data using Pythia event generator we need to include two values of kT.

Cuautle, Eleazar; Dominguez, Isabel; Paic, Guy [Instituto de Ciencias Nucleares, UNAM, A. P. 70543, 04510 Mexico City (Mexico)

2006-09-25

149

Analytic method for determining astronomical azimuths.  

National Technical Information Service (NTIS)

The analytic method for determining astronomical azimuths is a new means, put forward recently by the author, and a new theory as well. Suppose that near the diurnal apparent motion circle of the Polaris exist a fitting ellipse, with the north celestial p...

Jia Jingyun

1996-01-01

150

Reflection seismology over azimuthally anisotropic media  

Microsoft Academic Search

Recent surveys have shown that azimuthal anisotropy (due most plausibly to aligned fractures) has an impor- tant effect on seismic shear waves. Previous work had discussed these effects on VSP data; the same effects are seen in surface recording of reflections at small to mod- erate angles of incidence. The anisotropic effects one dif- ferent polarization components of vertically traveling

Leon Thomsen

1988-01-01

151

Azimuthal velocity in supercritical circular Couette flow  

Microsoft Academic Search

Although the stability of supercritical circular Couette flow has been studied extensively, results for the velocity field of the flow are limited. The azimuthal velocity profiles for the Taylor vortex, wavy vortex, and turbulent Taylor vortex flow in the annulus between a rotating inner cylinder and a fixed outer cylinder with fixed end conditions were measured using laser Doppler velocimetry.

S. T. Wereley; R. M. Lueptow

1994-01-01

152

Space-Time Dependent Transport, Activation, and Dose Rates for Radioactivated Fluids  

Microsoft Academic Search

Two methods are developed to calculate the space - and time-dependent mass transport of radionuclides, their production and decay, and the associated dose rates generated from the radioactivated fluids flowing through pipes. The work couples space- and time-dependent phenomena, treated as only space- or time-dependent in the open literature. The transport and activation methodology (TAM) is used to numerically calculate

Sergio Gavazza

1992-01-01

153

Proton-dependent coniferin transport, a common major transport event in differentiating xylem tissue of woody plants.  

PubMed

Lignin biosynthesis is an essential physiological activity of vascular plants if they are to survive under various environmental stresses on land. The biosynthesis of lignin proceeds in the cell wall by polymerization of precursors; the initial step of lignin polymerization is the transportation of lignin monomers from the cytosol to the cell wall, which is critical for lignin formation. There has been much debate on the transported form of the lignin precursor, either as free monolignols or their glucosides. In this study, we performed biochemical analyses to characterize the membrane transport mechanism of lignin precursors using angiosperms, hybrid poplar (Populus sieboldii × Populus grandidentata) and poplar (Populus sieboldii), as well gymnosperms, Japanese cypress (Chamaecyparis obtusa) and pine (Pinus densiflora). Membrane vesicles prepared from differentiating xylem tissues showed clear ATP-dependent transport activity of coniferin, whereas less than 4% of the coniferin transport activity was seen for coniferyl alcohol. Bafilomycin A1 and proton gradient erasers markedly inhibited coniferin transport in hybrid poplar membrane vesicles; in contrast, vanadate had no effect. Cis-inhibition experiments suggested that this transport activity was specific for coniferin. Membrane fractionation of hybrid poplar microsomes demonstrated that transport activity was localized to the tonoplast- and endomembrane-rich fraction. Differentiating xylem of Japanese cypress exhibited almost identical transport properties, suggesting the involvement of a common endomembrane-associated proton/coniferin antiport mechanism in the lignifying tissues of woody plants, both angiosperms and gymnosperms. PMID:23585651

Tsuyama, Taku; Kawai, Ryo; Shitan, Nobukazu; Matoh, Toru; Sugiyama, Junji; Yoshinaga, Arata; Takabe, Keiji; Fujita, Minoru; Yazaki, Kazufumi

2013-04-12

154

CONCENTRATION DEPENDENT TRANSPORT OF COLLOIDS IN SATURATED POROUS MEDIA  

Technology Transfer Automated Retrieval System (TEKTRAN)

A series of soil column experiments was undertaken to explore the influence of colloid input concentration on the transport and fate of several colloid sizes in three soils. Stable mono-dispersed colloids and porous media that are negatively charged were employed in these studies. Decreasing the col...

155

Sugar transport in Sulfolobus solfataricus is mediated by two families of binding protein-dependent ABC transporters  

Microsoft Academic Search

The extreme thermoacidophilic archaeon Sulfolobus solfataricus grows optimally at 80°C and pH 3 and uses a variety of sugars as sole carbon and energy source. Glucose transport in this organism is mediated by a high-affinity binding protein-dependent ATP-binding cassette (ABC) transporter. Sugar-binding studies revealed the presence of four additional membrane-bound binding proteins for arabinose, cellobiose, maltose and trehalose. These glycosylated

Marieke G. L. Elferink; Sonja-V. Albers; Wil N. Konings; Arnold J. M. Driessen

2001-01-01

156

Energy-dependent, high-affinity transport of nickel by the acetogen Clostridium thermoaceticum  

SciTech Connect

The nickel transport system of Clostridium thermoaceticum was investigated with {sup 63}NiCl{sub 2} and an anaerobic microfiltration transport assay. Transport was optimal at pH 7 to pH 7.5 and 65{degree}C and decreased in the presence of metabolic uncouplers and inhibitors. Exogenous nickel was concentrated 3,000-fold over the apparent nickel concentration gradient during typical transport assays. Stored cellular energy appeared to provide a short-term energy source to power nickel transport, and starvation experiments demonstrated external energy source stimulation of nickel translocation. The apparent K{sub m} and V{sub max} for nickel transport by carbon monoxide-dependent chemolithotrophic cells approximated 3.2 {mu}M Ni and 400 pmol of Ni transported per min per mg of cells (dry weight), respectively. Magnesium, calcium, cobalt, iron, manganese, and zinc did not inhibit the transport of nickel.

Lundie, L.L. Jr.; Yang, H.; Heinonen, J.K.; Dean, S.I.; Drake, H.L. (Univ. of Mississippi (USA))

1988-12-01

157

Azimuth and Range Optimization of the Velocity Azimuth Display (VAD) Algorithm in the WSR-88D.  

National Technical Information Service (NTIS)

The Velocity Azimuth Display (VAD) algorithm occasionally produces inaccurate wind estimates for the VAD Wind Profile (VWP) product of the Weather Surveillance Radar 1988 Doppler (WSR-88D) System. Weather forecasters have observed differences between the ...

D. L. Craft

1998-01-01

158

Azimuthal anisotropy in central U+U collisions at STAR  

NASA Astrophysics Data System (ADS)

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 provides the possibility to study how the initial geometry of the nuclei affects the azimuthal distributions. This allows one to study a variety of topics such as local parity violation, path length dependence of jet quenching, and particle production in heavy ion collisions. In this talk,the two-particle cumulant, v2, from central U+U collisions at ?sNN= 193 GeV and central Au+Au collisions at ?sNN= 200 GeV for inclusive charged hadrons will be presented. The STAR Zero Degree Calorimeters were used to select the most central collisions. Differences were observed between the multiplicity dependence of v2 for central Au+Au and U+U collisions. The observed v2 slope results were compared to Glauber model predictions and it was seen that this model cannot explain the present results on the multiplicity dependence of v2 in central collisions.

Wang, Hui

2013-04-01

159

2. DETAIL OF THEODOLITE PYLON NORTH OF AZIMUTH ALIGNMENT SHED ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

2. DETAIL OF THEODOLITE PYLON NORTH OF AZIMUTH ALIGNMENT SHED (BLDG. 775). - Vandenberg Air Force Base, Space Launch Complex 3, Azimuth Alignment Shed, Napa & Alden Roads, Lompoc, Santa Barbara County, CA

160

Concentration dependent transport of colloids in saturated porous media  

Microsoft Academic Search

A series of column experiments was undertaken to explore the influence of colloid input concentration (2, 1, 0.5, and 0.25 times a reference concentration), colloid size (negatively charged 3.2 and 1.0 ?m carboxyl latex), and sand grain size (360, 240, and 150 ?m quartz sands) on transport and deposition. A similar mass of stable mono-dispersed colloids was added to each

Scott A. Bradford; Mehdi Bettahar

2006-01-01

161

Do Waves Carrying Orbital Angular Momentum Possess Azimuthal Linear Momentum?  

NASA Astrophysics Data System (ADS)

All beams are a superposition of plane waves, which carry linear momentum in the direction of propagation with no net azimuthal component. However, plane waves incident on a hologram can produce a vortex beam carrying orbital angular momentum that seems to require an azimuthal linear momentum, which presents a paradox. We resolve this by showing that the azimuthal momentum is not a true linear momentum but the azimuthal momentum density is a true component of the linear momentum density.

Speirits, Fiona C.; Barnett, Stephen M.

2013-09-01

162

Feedback Control Of An Azimuthal Oscillation In The ExB Discharge of Hall Thrusters  

SciTech Connect

Feedback control of a low-frequency azimuthal wave known as a "rotating spoke" in the ExB 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 x 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 cause 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%.

Martin E. Griswold, C.L. Ellison, Y. Raitses and N.J. Fisch

2012-04-06

163

pH-Dependence of water and solute transport in toad urinary bladder  

Microsoft Academic Search

pH-Dependence of water and solute transport in toad urinary bladder. Stimulation of urea and water transport by vasopressin (ADH) appears to occur via independent pathways. We examined the effects of altering serosal or mucosal bath pH on transport of water, urea, and sodium. Compared to bladders with a serosal bath pH of 7.4 to 8.0, reducing the serosal bath pH

Christos P Carvounis; Sherman D Levine; Richard M Hays

1979-01-01

164

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

Microsoft Academic Search

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

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

2005-01-01

165

A DESCRIPTION OF A TIME DEPENDENT RADIATION HYDRODYNAMICS TRANSPORT CODE AND SOME NUMERICAL RESULTS  

Microsoft Academic Search

A description of a time-dependent radiation transport code is given. ; The transport equation is written in a form such that the flow of radiation is ; along the characteristics in space-time. Energy conservation, the equation of ; state, and the hydrodynamic equations are writien in a finite difference form. ; Numerical results to several problems of varying degrees of

Byatt

1962-01-01

166

Stacking-order dependent transport properties of trilayer graphene  

NASA Astrophysics Data System (ADS)

We report markedly different transport properties of ABA- and ABC-stacked trilayer graphenes. Our experiments in double-gated trilayer devices provide evidence that a perpendicular electric field opens an energy gap in the ABC trilayer, while it causes the increase of a band overlap in the ABA trilayer. In a perpendicular magnetic field, the ABA trilayer develops quantum Hall plateaus at filling factors of ?=2,4,6,... with a step of ??=2, whereas the inversion-symmetric ABC trilayer exhibits plateaus at ?=6 and 10 with fourfold spin and valley degeneracy.

Jhang, S. H.; Craciun, M. F.; Schmidmeier, S.; Tokumitsu, S.; Russo, S.; Yamamoto, M.; Skourski, Y.; Wosnitza, J.; Tarucha, S.; Eroms, J.; Strunk, C.

2011-10-01

167

Molecular and Functional Characterization of the Intestinal Na +Dependent Multivitamin Transporter  

Microsoft Academic Search

We have cloned a Na+-dependent multivitamin transporter from rabbit intestine (riSMVT). The cDNA codes for a protein of 636 amino acids with 12 putative transmembrane domains. When expressed in mammalian cells, the cDNA induces Na+-dependent uptake of the vitamins pantothenate and biotin. Lipoate is also a substrate for the cDNA-induced uptake process. The affinity constant for the cDNA-specific transport of

Puttur D. Prasad; Haiping Wang; Wei Huang; You-Jun Fei; Frederich H. Leibach; Lawrence D. Devoe; Vadivel Ganapathy

1999-01-01

168

A Time-Dependent Neutron Transport Model and its Coupling to Thermal-Hydraulics  

Microsoft Academic Search

A new neutron transport code for time-dependent analyses of nuclear systems has been developed. The code system is based on the well-known Discrete Ordinates code DORT, which solves the steady-state neutron\\/photon transport equation in two dimensions for an arbitrary number of energy groups and the most common regular geometries. For the implementation of time-dependence a fully implicit first-order scheme was

A. Pautz

169

Azimuthal instability of spinning spatiotemporal solitons  

PubMed

We find one-parameter families of three-dimensional spatiotemporal bright vortex solitons (doughnuts, or spinning light bullets), in dispersive quadratically nonlinear media. We show that they are subject to a strong instability against azimuthal perturbations, similarly to the previously studied (2+1)-dimensional bright spatial vortex solitons. The instability breaks the spinning soliton into several fragments, each being a stable nonspinning light bullet. PMID:11088714

Mihalache; Mazilu; Crasovan; Malomed; Lederer

2000-08-01

170

Use of the azimuthal resistivity technique for determination of regional azimuth of transmissivity  

USGS Publications Warehouse

Many bedrock units contain joint sets that commonly act as preferred paths for the movement of water, electrical charge, and possible contaminants associated with production or transit of crude oil or refined products. To facilitate the development of remediation programs, a need exists to reliably determine regional-scale properties of these joint sets: azimuth of transmissivity ellipse, dominant set, and trend(s). The surface azimuthal electrical resistivity survey method used for local in situ studies can be a noninvasive, reliable, efficient, and relatively cost-effective method for regional studies. The azimuthal resistivity survey method combines the use of standard resistivity equipment with a Wenner array rotated about a fixed center point, at selected degree intervals, which yields an apparent resistivity ellipse from which joint-set orientation can be determined. Regional application of the azimuthal survey method was tested at 17 sites in an approximately 500 km2 (193 mi2) area around Milwaukee, Wisconsin, with less than 15m (50 ft) overburden above the dolomite. Results of 26 azimuthal surveys were compared and determined to be consistent with the results of two other methods: direct observation of joint-set orientation and transmissivity ellipses from multiple-well-aquifer tests. The average of joint-set trend determined by azimuthal surveys is within 2.5?? of the average of joint-set trend determined by direct observation of major joint sets at 24 sites. The average of maximum of transmissivity trend determined by azimuthal surveys is within 5.7?? of the average of maximum of transmissivity trend determined for 14 multiple-well-aquifer tests. Copyright ?? 2010 The American Association of Petroleum Geologists/Division of Environmental Geosciences. All rights reserved.

Carlson, D.

2010-01-01

171

Spin and valley dependent electronic transport in strain engineered graphene  

NASA Astrophysics Data System (ADS)

We study the effect of the gauge potential Avec S induced by a local strain on electronic transport in a strain engineered graphene junction. For the normal/strained/normal/strained/normal graphene junction, by changing the sign of Avec S the K and K' valleys are interchanged, the conductance can change from finite to zero, so we obtain the valley valve effect. For the ferromagnetic/strained/ferromagnetic graphene junction in the parallel magnetization configuration by adjusting the gauge potential strength AS only the incident electrons in the spin-down channel are allowed to transmit, thus we can observe the strain-tunable spin filter effect. The magnetoresistance increases with AS and can reach up to 100%. It is expected these features may be helpful in the design of the strain-tunable spintronic devices.

Niu, ZhiPing

2012-05-01

172

Rat Liver Canalicular Membrane Vesicles Contain an ATP-Dependent Bile Acid Transport System  

NASA Astrophysics Data System (ADS)

The secretion of bile by the liver is primarily determined by the ability of the hepatocyte to transport bile acids into the bile canaliculus. A carrier-mediated process for the transport of taurocholate, the major bile acid in humans and rats, was previously demonstrated in canalicular membrane vesicles from rat liver. This process is driven by an outside-positive membrane potential that is, however, insufficient to explain the large bile acid concentration gradient between the hepatocyte and bile. In this study, we describe an ATP-dependent transport system for taurocholate in inside-out canalicular membrane vesicles from rat liver. The transport system is saturable, temperature-dependent, osmotically sensitive, specifically requires ATP, and does not function in sinusoidal membrane vesicles and right side-out canalicular membrane vesicles. Transport was inhibited by other bile acids but not by substrates for the previously demonstrated ATP-dependent canalicular transport systems for organic cations or nonbile acid organic anions. Defects in ATP-dependent canalicular transport of bile acids may contribute to reduced bile secretion (cholestasis) in various developmental, inheritable, and acquired disorders.

Nishida, Toshirou; Gatmaitan, Zenaida; Che, Mingxin; Arias, Irwin M.

1991-08-01

173

Diameter-dependent ion transport through the interior of isolated single-walled carbon nanotubes  

NASA Astrophysics Data System (ADS)

Nanopores that approach molecular dimensions demonstrate exotic transport behaviour and are theoretically predicted to display discontinuities in the diameter dependence of interior ion transport because of structuring of the internal fluid. No experimental study has been able to probe this diameter dependence in the 0.5-2?nm diameter regime. Here we observe a surprising fivefold enhancement of stochastic ion transport rates for single-walled carbon nanotube centered at a diameter of approximately 1.6?nm. An electrochemical transport model informed from literature simulations is used to understand the phenomenon. We also observe rates that scale with cation type as Li+>K+>Cs+>Na+ and pore blocking extent as K+>Cs+>Na+>Li+ potentially reflecting changes in hydration shell size. Across several ion types, the pore-blocking current and inverse dwell time are shown to scale linearly at low electric field. This work opens up new avenues in the study of transport effects at the nanoscale.

Choi, Wonjoon; Ulissi, Zachary W.; Shimizu, Steven F. E.; Bellisario, Darin O.; Ellison, Mark D.; Strano, Michael S.

2013-09-01

174

Magnetism-dependent transport phenomena in hydrogenated graphene: from spin-splitting to localization effects.  

PubMed

Spin-dependent transport in hydrogenated two-dimensional graphene is explored theoretically. Adsorbed atomic hydrogen impurities can either induce a local antiferromagnetic, ferromagnetic, or nonmagnetic state depending on their density and relative distribution. To describe the various magnetic possibilities of hydrogenated graphene, a self-consistent Hubbard Hamiltonian, optimized by ab initio calculations, is first solved in the mean field approximation for small graphene cells. Then, an efficient order N Kubo transport methodology is implemented, enabling large scale simulations of functionalized graphene. Depending on the underlying intrinsic magnetic ordering of hydrogen-induced spins, remarkably different transport features are predicted for the same impurity concentration. Indeed, while the disordered nonmagnetic graphene system exhibits a transition from diffusive to localization regimes, the intrinsic ferromagnetic state exhibits unprecedented robustness toward quantum interference, maintaining, for certain resonant energies, a quasiballistic regime up to the micrometer scale. Consequently, low temperature transport measurements could unveil the presence of a magnetic state in weakly hydrogenated graphene. PMID:21469688

Leconte, Nicolas; Soriano, David; Roche, Stephan; Ordejon, Pablo; Charlier, Jean-Christophe; Palacios, J J

2011-04-20

175

Strain dependence of the heat transport properties of graphene nanoribbons  

NASA Astrophysics Data System (ADS)

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 Å. 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.

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

2012-12-01

176

Strain dependence of the heat transport properties of graphene nanoribbons.  

PubMed

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

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

2012-11-13

177

Surface harmonics method equations for solving the time-dependent neutron transport problems and their verification  

SciTech Connect

Finite-difference time-dependent equations of Surface Harmonics method have been obtained for plane geometry. Verification of these equations has been carried out by calculations of tasks from 'Benchmark Problem Book ANL-7416'. The capacity and efficiency of the Surface Harmonics method have been demonstrated by solution of the time-dependent neutron transport equation in diffusion approximation. The results of studies showed that implementation of Surface Harmonics method for full-scale calculations will lead to a significant progress in the efficient solution of the time-dependent neutron transport problems in nuclear reactors. (authors)

Boyarinov, V. F.; Kondrushin, A. E.; Fomichenko, P. A. [National Research Center, Kurchatov Inst., Kurchatov Sq. 1, Moscow (Russian Federation)

2012-07-01

178

Higher twist contributions to the azimuthal asymmetries in semi-inclusive DIS  

SciTech Connect

In this talk, I summarize the conclusions and results that we obtained in recent publications to calculate the higher twist contributions to the azimuthal asymmetries in semi-inclusive deep inelastic lepton-nucleon and/or lepton-nucleus scattering. We show that the collinear expansion can be extended to the semi-inclusive scattering process l+p{yields}l+q+X, where q represents the struck quark and corresponds to the current jet in experiments. We present the results for the differential cross section and the azimuthal asymmetries up to twist-4 and discuss the nuclear dependence.

Liang Zuotang [School of physics, Shandong University, Jinan, Shandong 250100 (China)

2011-12-14

179

Radial and Azimuthal Polarizer Using a One-Dimensional Photonic Crystal with a Patterned Liquid Crystal Defect Layer  

NASA Astrophysics Data System (ADS)

We propose a radial and azimuthal polarizer (RAP) using a one-dimensional photonic crystal (1D PhC) with a patterned liquid crystal defect layer. A concentrically aligned liquid crystal defect layer in the 1D PhC causes the defect modes to be polarized azimuthally or radially, depending on the wavelength. Switching between these two polarizations is achieved by controlling the incident light wavelength.

Tagashira, Kenji; Yoshida, Hiroyuki; Kubo, Hitoshi; Fujii, Akihiko; Ozaki, Masanori

2010-06-01

180

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

SciTech Connect

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.

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

181

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

NASA Astrophysics Data System (ADS)

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.

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

2012-08-01

182

ATP-dependent transport of vinblastine in vesicles from human multidrug-resistant cells  

SciTech Connect

Resistance of human cancer cells to multiple cytotoxic hydrophobic agents (multidrug resistance) is due to overexpression of the MDR1 gene, whose product is the plasma membrane P-glycoprotein. Plasma membrane vesicles partially purified from multidrug-resistant human KB carcinoma cells, but not from drug-sensitive cells, accumulate ({sup 3}H)vinblastine in an ATP-dependent manner. This transport is osmotically sensitive, with an apparent K{sub m} of 38 {mu}M for ATP and of {approx} 2 {mu}M for vinblastine. The nonhydrolyzable analog adenosine 5{prime}-({beta},{gamma}-imido)triphosphate does not substitute for ATP but is a competitive inhibitor of ATP for the transport process. Vanadate, and ATPase inhibitor, is a potent noncompetitive inhibitor of transport. These results indicate that hydrolysis of ATP is probably required for active transport vinblastine. Several other drugs to which multidrug-resistant cell lines are resistant inhibit transport, with relative potencies as follows: vincristine > actinomycin D > daunomycin > colchicine = puromycin. Verapamil and quinidine, which reverse the multidrug-resistance phenotype, are good inhibitors of the transport process. These results confirm that multidrug-resistant cells express an energy-dependent plasma membrane transporter for hydrophobic drugs, and establish a system for the detailed biochemical analysis of this transport process.

Horio, M.; Gottesman, M.M.; Pastan, I. (National Institutes of Health, Bethesda, MD (USA))

1988-05-01

183

Transcellular Transport of Benzole Acid Across Caco-2 Cells by a pH-Dependent and Carrier-Mediated Transport Mechanism  

Microsoft Academic Search

The pH-dependent transcellular transport of [14 C]benzoic acid across a Caco-2 cell monolayer is shown to be mediated by a monocarboxylic acid-specific carrier-mediated transport system, localized on the apical membrane. Evidence for the carrier-mediated transport of benzoic acid includes (a) the significant temperature and concentration dependence, (b) the metabolic energy dependence, (c) the inhibition by unlabeled benzoic acid and other

Akira Tsuji; Hitomi Takanaga; Ikumi Tamai; Tetsuya Terasaki

1994-01-01

184

Efficient Computation of Time-Dependent Centralities in Air Transportation Networks  

Microsoft Academic Search

\\u000a We introduce indices of centrality to analyze air transportation networks which represent the importance of airports and individual\\u000a flights dependent on the time of the day (time-dependent centrality indices). Our centrality indices are based on earliest\\u000a arrival paths with a minimum number of transfers in a time- and event-dependent network model. This means, that all paths\\u000a correspond to real connections,

Annabell Berger; Matthias Müller-Hannemann; Steffen Rechner; Alexander Zock

2011-01-01

185

Azimuth determination for vector sensor tools  

SciTech Connect

This invention relates to mapping or survey apparatus and methods, and more particularly concerns derivation of the azimuth output indications for such apparatus in a borehole from the outputs or output indications of either an inertial angular rate vector sensor (or sensors) and an acceleration vector sensor (or sensors), or a magnetic field vector sensor (or sensors), and from the outputs of an acceleration vector sensor (or sensors). At least one of such sensors in any instrument may be canted relative to the borehole axis. Borehole tilt is also derived.

Ott, P. W.; Engebretson, H. J.; Lahue, P. M.; Van Steenwyk, B. H.

1985-12-24

186

Using an electronic compass to determine telemetry azimuths  

USGS Publications Warehouse

Researchers typically collect azimuths from known locations to estimate locations of radiomarked animals. Mobile, vehicle-mounted telemetry receiving systems frequently are used to gather azimuth data. Use of mobile systems typically involves estimating the vehicle's orientation to grid north (vehicle azimuth), recording an azimuth to the transmitter relative to the vehicle azimuth from a fixed rosette around the antenna mast (relative azimuth), and subsequently calculating an azimuth to the transmitter (animal azimuth). We incorporated electronic compasses into standard null-peak antenna systems by mounting the compass sensors atop the antenna masts and evaluated the precision of this configuration. This system increased efficiency by eliminating vehicle orientation and calculations to determine animal azimuths and produced estimates of precision (azimuth SD=2.6 deg., SE=0.16 deg.) similar to systems that required orienting the mobile system to grid north. Using an electronic compass increased efficiency without sacrificing precision and should produce more accurate estimates of locations when marked animals are moving or when vehicle orientation is problematic.

Cox, R. R., Jr.; Scalf, J. D.; Jamison, B. E.; Lutz, R. S.

2002-01-01

187

Spin-dependent transport through point-contacts  

NASA Astrophysics Data System (ADS)

A point-contact spectroscopy technique has been used to study (1) the spin polarization of several ferromagnetic materials, including candidates of half-metallic ferromagnets, and (2) spin-transfer torque effects (more specifically current-induced spin-wave excitations) in single ferromagnetic layers. The values of spin polarization of common ferromagnetic materials (Ni, Co and Fe) have been measured by the point-contact Andreev reflection (PCAR) technique. PCAR uses a sharp superconducting tip to create a small-area interface between the superconductor and the material to be measured. Conductance vs. bias voltage curves have been recorded at helium temperature for specific contacts. Strong nonlinearity exists in the G - V curves due to the Andreev reflection, the process of normal-currentto-supercurrent conversion. The probability of Andreev reflection will be suppressed if the metal is a ferromagnet with certain degree of spin polarization at the Fermi level. Proper quantitative analyses of a conductance curve yield the value of spin polarization P and the strength of interfacial scattering Z. A systematic dependence of P upon Z has been demonstrated and attributed to spin-flip scattering. Most importantly, the intrinsic value of spin polarization can be uniquely determined in the limit of Z = 0, an ideally clean interface. A few candidates of half-metallic ferromagnets, materials with 100% spin polarization, have been studied using the PCAR technique. Single-crystal CrO 2 has been demonstrated to be indeed half-metallic with a polarization no less than 0.96. Strontium doped Lanthenum manganites, La0.7Sr 0.3MnO3 and La0.6Sr0.4MnO3, are highly spin-polarized with P ˜ 0.80, but are unlikely to be half-metallic. Certain compositions of Heusler alloys, NiMnSb and Co 2MnSi, have also been found to have significant P but with no evidence of half-metallicity. The spin-transfer torque effect, the fact that a spin-polarized current is able to impart a torque upon a ferromagnetic entity and thereby alters its magnetic configuration, has been demonstrated in a single ferromagnetic layer, without resorting to multilayer structures. (Abstract shortened by UMI.)

Ji, Yi

188

Requirement for Na(+)-dependent ascorbic acid transport in osteoblast function.  

PubMed

Ascorbic acid is necessary for expression of the osteoblast phenotype. We examined whether Na(+)-dependent transport is required for MC3T3-E1 preosteoblast cells to respond to vitamin C and investigated the role of membrane transport in the intracellular accumulation and function of ascorbate. MC3T3-E1 cells were found to possess a saturable, stereoselective, Na(+)-dependent ascorbic acid transport activity that is sensitive to the transport inhibitors sulfinpyrazone, 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid, and phloretin. Transport activity showed no competition with glucose or 2-deoxyglucose and was not inhibited by cytochalasin B, indicating that it is distinct from known hexose transporters. On addition of 100 microM ascorbic acid to the extracellular medium, intracellular concentrations of 10 mM were reached within 5-10 h and remained constant for up to 24 h. A good correlation was observed between intracellular ascorbic acid concentration and rate of hydroxyproline synthesis. Although ascorbic acid was transported preferentially compared with D-isoascorbic acid, both isomers had equivalent activity in stimulating hydroxyproline formation once they entered cells. Marked stereoselectivity for extracellular L-ascorbic acid relative to D-isoascorbic acid was also seen when alkaline phosphatase and total hydroxyproline were measured after 6 days in culture. Moreover, ascorbic acid transport inhibitors that prevented intracellular accumulation of vitamin blocked the synthesis of hydroxyproline. Thus Na(+)-dependent ascorbic acid transport is required for MC3T3-E1 cells to achieve the millimolar intracellular vitamin C concentrations necessary for maximal prolyl hydroxylase activity and expression of the osteoblast phenotype. PMID:7611363

Franceschi, R T; Wilson, J X; Dixon, S J

1995-06-01

189

Atlantic and Mediterranean Tables of Communication Station Azimuths and LORAN-C Station Azimuths and Distances.  

National Technical Information Service (NTIS)

The tables in SP-272-1 are designed for users of the Navy Communications Stations and LORAN-C Stations. The tables give azimuths to communication and LORAN-C stations, and distances to LORAN-C stations. Index diagrams of coverage of the various tables are...

1979-01-01

190

First-principles study of spin-dependent transport through graphene/BNC/graphene structure  

PubMed Central

First-principles study on the electronic structure and transport property of the boron nitride sheet (BNC) structure, in which a triangular graphene flake surrounded by a hexagonal boron nitride sheet, is implemented. As the graphene flake becomes small and is more isolated by the boron nitride region, the magnetic ordering of the flake increases. When the BNC structure is connected to the graphene electrodes, the spin-polarized charge-density distribution appears only at the triangular graphene flake region, and the electronic structure of the graphene electrode is not spin polarized. First-principles transport calculation reveals that the transport property of the BNC structure is spin dependent.

2013-01-01

191

Time-dependent approach to transport and scattering in atomic and mesoscopic physics  

SciTech Connect

Transport and scattering phenomena in open quantum-systems with a continuous energy spectrum are conveniently solved using the time-dependent Schroedinger equation. In the time-dependent picture, the evolution of an initially localized wave-packet reveals the eigenstates and eigenvalues of the system under consideration. We discuss applications of the wave-packet method in atomic, molecular, and mesoscopic systems and point out specific advantages of the time-dependent approach. In connection with the familiar initial value formulation of classical mechanics, an intuitive interpretation of transport emerges. For interacting many-particle systems, we discuss the efficient calculation of the self-consistent classical transport in the presence of a magnetic field.

Kramer, Tobias [Institut fuer Theoretische Physik, Universitaet Regensburg, 93040 Regensburg (Germany)

2011-03-21

192

Sodium-dependent transport of [3H](1D)chiro-inositol by Tetrahymena.  

PubMed

The transport characteristics of (1D)chiro-inositol by the ciliate Tetrahymena were examined in competition studies employing [3H](1D)chiro-inositol. (1D)chiro-Inositol transport was competed by unlabeled (1D)chiro-inositol, myo-inositol, scyllo-inositol, and D-glucose in a concentration-dependent manner. Conversely, (1D)chiro-inositol competed for [3H]myo- and [3H]scyllo-inositol transport. Lineweaver-Burke analysis of the competition data indicated a Km of 10.3 mM and a Bmax of 4.7 nmol/min/mg for (1D)chiro-inositol. Transport of (1D)chiro-inositol was inhibited by cytochalasin B, an inhibitor of facilitated glucose transporters, and phlorizin, an inhibitor of sodium-dependent transporters. Removal of sodium from the radiolabeling buffer also inhibited uptake. The presence of 0.64 mM calcium or magnesium ions exerted negligible effects on transport, although potassium was inhibitory. [3H](1D)chiro-Inositol was shown to be incorporated into Tetrahymena phosphoinositides. PMID:15218699

Kersting, Michael C; Ryals, Phillip E

193

Abnormal postprandial duodenal chyme transport in patients with long standing insulin dependent diabetes mellitus  

PubMed Central

Abstract ?Background—Patients with long standing diabetes mellitus frequently have upper gut dysmotility. Gastroparesis has been well studied, whereas detailed data on duodenal motor function are limited. ?Aims—To characterise postprandial duodenal chyme transport in such patients. ?Methods—Intraluminal multiple impedance measurement, recently introduced as a novel technique for investigation of chyme transport, was used to study postprandial duodenal chyme flow in 10 patients with long standing insulin dependent diabetes mellitus with gastroparesis, and 10 healthy volunteers. ?Results—Four distinct transport patterns of chyme, termed bolus transport events (BTEs), were found in both groups and could be characterised as: short distance propulsive; simple long distance propulsive; retrograde; and complex long distance propulsive. Diabetic patients had significantly lower numbers of propulsive BTEs (p<0.01), and higher proportions of retrograde BTEs and complex long distance BTEs (p<0.05) than control subjects, whereas the proportion of simple long distance BTEs was significantly lower (p<0.05). The mean propagation velocities of the BTEs were similar in both groups. ?Conclusion—Abnormal postprandial duodenal chyme transport was found in patients with long standing insulin dependent diabetes mellitus. This is characterised by transport disorganisation and may result in disturbed chyme clearance. ?? Keywords: diabetic gastroparesis syndrome; postprandial chyme transport; intraluminal impedance measurement

Nguyen, H; Silny, J; Wuller, S; Marschall, H; Rau, G; Matern, S

1997-01-01

194

Amphetamine induces a calcium/calmodulin-dependent protein kinase II-dependent reduction in norepinephrine transporter surface expression linked to changes in syntaxin 1A/transporter complexes.  

PubMed

Norepinephrine (NE) transporters (NETs) are high-affinity transport proteins that mediate the synaptic clearance of NE after vesicular release. NETs represent a major therapeutic target for antidepressants and are targets of multiple psychostimulants including amphetamine (AMPH) and cocaine. Recently, we demonstrated that syntaxin 1A (SYN1A) regulates NET surface expression and, through binding to the transporter's NH(2) terminus, regulates transporter catalytic function. AMPH induces NE efflux and may also regulate transporter trafficking. We monitored NET distribution and function in catecholaminergic cell lines (CAD) stably transfected with either full-length human NET (CAD-hNET) or with an hNET N-terminal deletion (CAD-hNETDelta(28-47) cells). In hNET-CAD cells, AMPH causes a slow and small reduction of surface hNET with a modest increase in hNET/SYN1A associations at the plasma membrane. In contrast, in CAD-hNETDelta(28-47) cells, AMPH induces a rapid and substantial reduction in surface hNETDelta(28-47) accompanied by a large increase in plasma membrane hNETDelta(28-47)/SYN1A complexes. We also found that AMPH in CAD-hNETDelta(28-47) cells induces a robust increase in cytosolic Ca2+ and concomitant activation of calcium/calmodulin-dependent protein kinase II (CaMKII). Inhibition of either the increase in intracellular Ca2+ or CaMKII activity blocks AMPH-stimulated hNETDelta(28-47) trafficking and the formation of hNETDelta(28-47)/SYN1A complexes. Here, we demonstrate that AMPH stimulation of CAMKII stabilizes an hNET/SYN1A complex. This hNET/SYN1A complex rapidly redistributes, upon AMPH treatment, when mechanisms supported by the transporter's NH2 terminus are eliminated. PMID:17032905

Dipace, Concetta; Sung, Uhna; Binda, Francesca; Blakely, Randy D; Galli, Aurelio

2006-10-10

195

Drell-Yan Lepton Pair Azimuthal Asymmetry in Hadronic Processes  

SciTech Connect

We study the azimuthal asymmetry in the Drell-Yan lepton pair production in hadronic scattering processes at moderate transverse momentum region, taking into account the contributions from the twist-three quark-gluon correlations from the unpolarized hadrons. The contributions are found to dominate the asymmetry, and are not power suppressed by qt/Q at small qt where qt and Q are the transverse momentum and invariant mass of the lepton pair. Accordingly, the Lam-Tung relation will be violated at this momentum region, and its violation depends on the twist-three functions. However, at large transverse momentum qt~;;Q, the Lam-Tung relation still holds because all corrections are power suppressed by Lambda2/qt2 ~;; Lambda2/Q2 where Lambda is the typical nonperturbative scale.

Zhou, Jian; Yuan, Feng; Liang, Zuo-Tang

2009-01-22

196

Azimuthal energy flow in deep inelastic neutrino scattering  

SciTech Connect

Gluon emission and the transverse momentum (p/sub t/) of partons confined in nucleons were studied using deep-inelastic charged-current neutrino-nucleon interactions. For this analysis we use the flow of hadronic energy in the azimuthal direction around the momentum transfer referenced from the neutrino-muon scattering plane. A five standard deviation asymmetry was found. Analysis of this asymmetry indicates a (p/sub t/) of 0.35 +- 0.12 GeV/c if QCD corrections are included, and 0.56 +- 0.05 GeV/c if they are excluded. Some evidence was also observed for x dependence in p/sub t/. Data were taken at Fermilab in 1982 using a 200 ton (fiducial mass) fine grained calorimeter and a dichromatic neutrino beam.

Mukherjee, A.; Bofill, J.; Busza, W.; Eldridge, T.F.; Friedman, J.I.; Fuess, S.; Goodman, M.C.; Kendall, H.W.; Lyons, T.F.; Magahiz, R.A.

1986-06-12

197

Binaural Sound Localizer for Azimuthal Movement Detection Based on Diffraction  

PubMed Central

Sound localization can be realized by utilizing the physics of acoustics in various methods. This paper investigates a novel detection architecture for the azimuthal movement of sound source based on the interaural level difference (ILD) between two receivers. One of the microphones in the system is surrounded by barriers of various heights in order to cast the direction dependent diffraction of the incoming signal. The gradient analysis of the ILD between the structured and unstructured microphone demonstrates the rotation directions as clockwise, counter clockwise, and no rotation of the sound source. Acoustic experiments with different types of sound source over a wide range of target movements show that the average true positive and false positive rates are 67% and 16%, respectively. Spectral analysis demonstrates that the low frequency delivers decreased true and false positive rates and the high frequency presents increases of both rates, overall.

Kim, Keonwook; Choi, Anthony

2012-01-01

198

Diameter-dependent electronic transport properties of Au-catalyst/Ge-nanowire Schottky diodes  

SciTech Connect

We present electronic transport measurements in individual Au-catalyst/Ge-nanowire interfaces demonstrating the presence of a Schottky barrier. Surprisingly, the small-bias conductance density increases with decreasing diameter. Theoretical calculations suggest that this effect arises because electron-hole recombination in the depletion region is the dominant charge transport mechanism, with a diameter dependence of both the depletion width and the electron-hole recombination time. The recombination time is dominated by surface contributions and depends linearly on the nanowire diameter.

Picraux, S Thomas [Los Alamos National Laboratory; Leonard, Francois [SNL; Swartzentruber, Brian S [SNL; Talin, A Alee [SNL

2008-01-01

199

Density dependence of trace tritium transport in H-mode Joint European Torus plasma  

NASA Astrophysics Data System (ADS)

Tritium transport in edge localized mode (ELM) high confinement (H-mode) plasmas is analyzed here as a function of density for discharges from the recent trace tritium experimental campaign performed on Joint European Torus. In this campaign small amounts of tritium have been puffed or injected (with neutral beam injectors) into deuterium plasmas [K.-D. Zastrow, J. M. Adams, Yu. Baranov et al., Plasma Phys. Controlled Fusion 46, B255 (2004)]. Information about the tritium has been obtained from the evolution of the profiles of neutron emission simulated via the TRANSP [R. J. Goldston, D. C. McCune, H. H. Towner, S. L. Davis, R. J. Hawryluk, and G. L. Schmidt, J. Comput. Phys. 43, 61 (1981)] and SANCO (L. Lauro-Taroni, B. Alper, R. Giannella, K. Lawson, F. Marcus, M. Mattioli, P. Smeulders, and M. Von Hellermann, Proceedings of the 21st European Conference on Controlled Fusion and Plasma Physics, Montpelier, France, 1994) codes. A strong inverse correlation of tritium transport with plasma density is found in this analysis. The low tritium transport at high density is close to neoclassical values while the transport becomes strongly anomalous in low density plasmas. The thermal transport does not exhibit such a strong density dependence, leading to a varying ratio of thermal to tritium transport in these discharges. An interpretation of the density effects on the trace tritium transport, partially based on the test particle simulations in plasmas with stochastic magnetic field, is proposed. A simple model for the tritium diffusion coefficient and convective velocity, which includes the modification of the neoclassical particle diffusion in presence of electromagnetic turbulence [A. I. Smolyakov and P. N. Yushmanov, Nucl. Fusion 35, 383 (1993)] completed with an empirical density dependence, is developed. This model has positive ? dependence in agreement with the results of the similarity experiments performed for trace tritium transport.

Voitsekhovitch, I.; Garbet, X.; McDonald, D. C.; Zastrow, K.-D.; Adams, M.; Baranov, Yu.; Belo, P.; Bertalot, L.; Budny, R.; Conroy, S.; Cordey, J. G.; Garzotti, L.; Mantica, P.; McCune, D.; Ongena, J.; Parail, V.; Popovichev, S.; Stork, D.; Whiteford, A. D.

2005-05-01

200

TOPSAR data focusing based on azimuth scaling preprocessing  

NASA Astrophysics Data System (ADS)

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.

Xu, Wei; Huang, Pingping; Deng, Yunkai

2011-07-01

201

14 CFR 171.313 - Azimuth performance requirements.  

Code of Federal Regulations, 2010 CFR

...provided for information only. (3) Antenna alignment. The antenna must be equipped with suitable optical, electrical or mechanical...02 degree. Additionally, the azimuth antenna bias adjustment must be...

2009-01-01

202

14 CFR 171.313 - Azimuth performance requirements.  

Code of Federal Regulations, 2010 CFR

...provided for information only. (3) Antenna alignment. The antenna must be equipped with suitable optical, electrical or mechanical...02 degree. Additionally, the azimuth antenna bias adjustment must be...

2010-01-01

203

Rab9-dependent retrograde transport and endosomal sorting of the endopeptidase furin  

PubMed Central

The endopeptidase furin and the trans-Golgi network protein TGN38 are membrane proteins that recycle between the TGN and plasma membrane. TGN38 is transported by a retromer-dependent pathway from early endosomes to the TGN, whereas the intracellular transport of furin is poorly defined. Here we have identified the itinerary and transport requirements of furin. Using internalisation assays, we show that furin transits the early and late endosomes en route to the TGN. The GTPase Rab9 and the TGN golgin GCC185, components of the late endosome-to-TGN pathway, were required for efficient TGN retrieval of furin. By contrast, TGN38 trafficking was independent of Rab9 and GCC185. To identify the sorting signals for the early endosome-to-TGN pathway, the trafficking of furin–TGN38 chimeras was investigated. The diversion of furin from the Rab9-dependent late-endosome-to-TGN pathway to the retromer-dependent early-endosome-to-TGN pathway required both the transmembrane domain and cytoplasmic tail of TGN38. We present evidence to suggest that the length of the transmembrane domain is a contributing factor in endosomal sorting. Overall, these data show that furin uses the Rab9-dependent pathway from late endosomes and that retrograde transport directly from early endosomes is dependent on both the transmembrane domain and the cytoplasmic tail.

Chia, Pei Zhi Cheryl; Gasnereau, Isabelle; Lieu, Zi Zhao; Gleeson, Paul A.

2011-01-01

204

Space-Time Dependent Transport, Activation, and Dose Rates for Radioactivated Fluids.  

NASA Astrophysics Data System (ADS)

Two methods are developed to calculate the space - and time-dependent mass transport of radionuclides, their production and decay, and the associated dose rates generated from the radioactivated fluids flowing through pipes. The work couples space- and time-dependent phenomena, treated as only space- or time-dependent in the open literature. The transport and activation methodology (TAM) is used to numerically calculate space- and time-dependent transport and activation of radionuclides in fluids flowing through pipes exposed to radiation fields, and volumetric radioactive sources created by radionuclide motions. The computer program Radionuclide Activation and Transport in Pipe (RNATPA1) performs the numerical calculations required in TAM. The gamma ray dose methodology (GAM) is used to numerically calculate space- and time-dependent gamma ray dose equivalent rates from the volumetric radioactive sources determined by TAM. The computer program Gamma Ray Dose Equivalent Rate (GRDOSER) performs the numerical calculations required in GAM. The scope of conditions considered by TAM and GAM herein include (a) laminar flow in straight pipe, (b)recirculating flow schemes, (c) time-independent fluid velocity distributions, (d) space-dependent monoenergetic neutron flux distribution, (e) space- and time-dependent activation process of a single parent nuclide and transport and decay of a single daughter radionuclide, and (f) assessment of space- and time-dependent gamma ray dose rates, outside the pipe, generated by the space- and time-dependent source term distributions inside of it. The methodologies, however, can be easily extended to include all the situations of interest for solving the phenomena addressed in this dissertation. A comparison is made from results obtained by the described calculational procedures with analytical expressions. The physics of the problems addressed by the new technique and the increased accuracy versus non -space and time-dependent methods are presented. The value of the methods is also discussed. It has been demonstrated that TAM and GAM can be used to enhance the understanding of the space- and time-dependent mass transport of radionuclides, their production and decay, and the associated dose rates related to radioactivated fluids flowing through pipes.

Gavazza, Sergio

205

Using variable-frequency asymmetries to probe the magnetic field dependence of radial transport in a Malmberg-Penning trap  

NASA Astrophysics Data System (ADS)

A new experimental technique is used to study the dependence of asymmetry-induced radial particle flux ? on axial magnetic field B in a modified Malmberg-Penning trap. This dependence is complicated by the fact that B enters the physics in at least two places: in the asymmetry-induced first order radial drift velocity vr = E?/B and in the zeroth order azimuthal drift velocity v? = Er/B. To separate these, we employ the hypothesis that the latter always enters the physics in the combination ?-l?R, where ?R = v?/r is the column rotation frequency and ? and l are the asymmetry frequency and azimuthal mode number, respectively. Points where ?-l?R = 0 are then selected from a ? vs r vs ? data set, thus insuring that any function of this combination is constant. When the selected flux ?sel is plotted versus the density gradient, a roughly linear dependence is observed, showing that this selected flux is diffusive. This linear dependence is roughly independent of the bias of the center wire in our trap ?cw. Since in our experiment ?R is proportional to ?cw, this latter point shows that our technique has successfully removed any dependence on ?R and its derivatives, thus confirming our hypothesis. The slope of a least-squares fitted line through the ?sel vs density gradient data then gives the diffusion coefficient D0 under the condition ?-l?R = 0. Varying the magnetic field, we find D0 is proportional to B-1.33+/-0.05, a scaling that does not match any theory we know. These findings are then used to constrain the form of the empirical flux equation. It may be possible to extend this technique to give the functional dependence of the flux on ?-l?R.

Eggleston, D. L.

2009-03-01

206

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

SciTech Connect

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.

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

207

Time domain waveform and azimuth variation of ionospherically reflected VLF/LF radio emissions from lightning  

NASA Astrophysics Data System (ADS)

The Earth's geomagnetic field can, in principle, cause significant magnetic-azimuth variations of the lower ionosphere's reflection of 2-150 kHz radio waves emitted by lightning. There has been little published work on this azimuth variation, either modeled or observational. We use broadband emissions from negative cloud-to-ground lightning strokes to study the azimuthal variations systematically. The data are from the Los Alamos Sferic Array, operating in the United States' southern Great Plains during 2005. We compare the observations to a model of lower-ionosphere reflection of radio waves. The model recapitulates the basic features of the time domain reflection waveforms rather well, except at the lowest frequencies. The model transfer function describing the vertical electric field at the receiver is symmetric about 90° magnetic and about 270° magnetic. Two noteworthy features of the azimuth variation are both predicted by the model, and seen in the data: First, at the lowest frequencies (<30 kHz) there is enhanced reflection for eastward propagation, relative to westward propagation. Second, at the higher frequencies (>50 kHz) there is an opposite enhancement, of the reflection for westward propagation, relative to eastward propagation. The westward enhancement at >50 kHz depends sensitively on range and is most evident in nighttime conditions, while the eastward enhancement at <30 kHz occurs at all ranges studied. Range-dependent frequency modulations of the transfer function are the least for magnetic northward propagation (duplicated by magnetic southward).

Jacobson, Abram R.; Shao, Xuan-Min; Lay, Erin

2012-08-01

208

CALCIUM-DEPENDENT INTERACTIONS OF THE HUMAN NOREPINEPHRINE TRANSPORTER WITH SYNTAXIN 1A  

PubMed Central

The norepinephrine (NE) transporter (NET) terminates noradrenergic signaling by clearing released NE at synapses. The activity of NET can be rapidly regulated by depolarization and receptor activation via Ca2+ and kinase/phosphatase linked pathways. The SNARE protein syntaxin 1A (SYN1A) interacts with NET and influences transporter surface trafficking and catalytic activity. In this study, we establish a link between changes in intracellular Ca2+ and SYN1A/NET interactions. SYN1A influenced NE transport only in the presence of Ca2+ in brain cortical synaptosomes. Although NET/SYN1A associations were sensitive to manipulations of Ca2+ in CHO cells, in vitro binding experiments using purified NET and SYN1A fusion proteins demonstrated a lack of direct Ca2+ sensitivity. Disruption of NET/SYN1A interaction abolished inhibition of NE transport by phorbol ester (PMA) to activate protein kinase C (PKC), but had no effect on transport inhibition by the Ca2+ calmodulin kinase (CaMK) inhibitor KN93. Furthermore, PMA enhanced Ca2+ dependent modulation of NE transport in synaptosomes. Our data reveal roles for SYN1A in the Ca2+-dependent regulation of NET, likely reliant on regulation by PKC signaling, but independent of CaMK.

Sung, Uhna; Blakely, Randy D.

2007-01-01

209

Localization of ATP-dependent calcium transport activity in mouse pancreatic microsomes  

Microsoft Academic Search

Summary Electron-dense deposits representing calcium oxalate crystals which results from ATP-dependent calcium uptake have been localized within vesicles of a heavy microsomal fraction prepared from mouse pancreatic acini. In the absence of either ATP or oxalate, no electron-dense deposits could be observed. By subfractionation of microsomes on discontinuous sucrose gradients, it could be shown that the highest energy-dependent calcium transport

Margret Preissler; John A. Williams

1983-01-01

210

Temperature dependence of antenna excitation transport in native photosystem I particles. [Electronic energy transport (EET)  

SciTech Connect

The temperature dependence of polarized photobleaching dynamics was investigated through 680-nm pump-probe experiments in the Chl a antenna of native photosystem 1 particles (Chl/P700 {approximately} 200) from spinach. The anisotropic decay time is lengthened by an order of magnitude (from {approximately}7 to {approximately}62 ps) when the temperature is reduced from 290 to 38 K; most of this increase occurs between 65 and 38 K. The occurrence of this transition temperature in the tens of kelvin reflects the participation of protein phonons in antenna EET. The isotopic decay kinetics are considerably less temperature sensitive, indicating that the anisotropic and isotropic decays stem from different energy-transfer processes with contrasting temperature dependence. The 38 K photobleaching spectrum at 5 ps exhibits considerably more weighting in the lower energy Chl a spectral forms than the room-temperature spectrum, suggesting that rapid spectral equilibration occurs in the photosystem 1 antenna. In light of the phonon frequency and electron-phonon coupling parameters determined in independent PSI-200 spectral hole-burning experiments, the quantitative temperature dependence int he anisotropic decay times is consistent with a theory for phonon-assisted EET in which the pertinent phonons are independent modes localized about the donor and acceptor chromophores.

Lyle, P.A.; Struve, W.S. (Ames Lab., IA (United States))

1991-05-16

211

Independent control of polar and azimuthal anchoring  

NASA Astrophysics Data System (ADS)

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.

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

2013-07-01

212

VACUUM calculation in azimuthally symmetric geometry  

SciTech Connect

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.

Chance, M.S.

1996-11-01

213

Hybrid Approach for the Public Transportation Time Dependent Orienteering Problem with Time Windows  

NASA Astrophysics Data System (ADS)

The Time Dependent Orienteering Problem with Time Windows (TDOPTW) consists of a set of locations with associated time windows and scores. Visiting a location allows to collect its score as a reward. Traveling time between locations varies depending on the leave time. The objective is to obtain a route that maximizes the obtained score within a limited amount of time. In this paper we target the use of public transportation in a city, where users may move on foot or by public transportation. The approach can also be applied to the logistic sector, for example to the multimodal freight transportation. We apply an hybrid approach to tackle the problem. Experimental results for the city of San Sebastian show we are able to obtain valid routes in real-time.

Garcia, Ander; Arbelaitz, Olatz; Vansteenwegen, Pieter; Souffriau, Wouter; Linaza, Maria Teresa

214

Observation of a large spin-dependent transport length in organic spin valves at room temperature  

NASA Astrophysics Data System (ADS)

The integration of organic semiconductors and magnetism has been a fascinating topic for fundamental scientific research and future applications in electronics, because organic semiconductors are expected to possess a large spin-dependent transport length based on weak spin-orbit coupling and weak hyperfine interaction. However, to date, this length has typically been limited to several nanometres at room temperature, and a large length has only been observed at low temperatures. Here we report on a novel organic spin valve device using C60 as the spacer layer. A magnetoresistance ratio of over 5% was observed at room temperature, which is one of the highest magnetoresistance ratios ever reported. Most importantly, a large spin-dependent transport length of approximately 110?nm was experimentally observed for the C60 layer at room temperature. These results provide insights for further understanding spin transport in organic semiconductors and may strongly advance the development of spin-based organic devices.

Zhang, Xianmin; Mizukami, Shigemi; Kubota, Takahide; Ma, Qinli; Oogane, Mikihiko; Naganuma, Hiroshi; Ando, Yasuo; Miyazaki, Terunobu

2013-01-01

215

Time-dependent transport of field-aligned bursts of electrons in flickering aurora  

Microsoft Academic Search

We have developed a time-dependent auroral electron transport model to study emission rates caused by field-aligned bursts of electrons (FABs) seen in flickering aurora. We simulate flickering FABs by turning on and off a downward electron intensity distribution at a given frequency. We assume this electron beam originates and is modulated at an altitude of 4000 km. We apply collisionless

L. Peticolas; D. Lummerzheim

2000-01-01

216

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

SciTech Connect

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.

T. Downar

2009-03-31

217

Employed Women as a Transportation-Deprived and Transit-Dependent Group.  

National Technical Information Service (NTIS)

In the design of the BART impact travelers study, housewives were specified as one of the transportation-deprived and transit-dependent population groups. However, review of the data suggested that this was not the case, at least among the east bay respon...

F. Carp

1974-01-01

218

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

Microsoft Academic Search

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

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

2004-01-01

219

Characterization of a Na+-dependent betaine transporter with Cl- channel properties in squid motor neurons.  

PubMed

Most marine invertebrates, including squids, use transporters to accumulate organic osmolytes such as betaine, to prevent water loss when exposed to elevated salinity. Although a limited number of flux studies have shown the Na+ dependence of betaine transport, nothing is known about the electrogenic properties of osmolyte transporters. We used whole cell and perforated-patch voltage-clamp techniques to characterize the electrical properties of the betaine transporter in giant fiber lobe motor neurons of the squid Lolliguncula brevis. Betaine activated a large, Cl--selective current that was reversibly blocked by 100 microM niflumic acid (97 +/- 2% block after 40 s, SD; n = 7) and partially inhibited by 500 microM SITS (29 +/- 11%; n = 5). The Cl- current was Na+ dependent and was virtually eliminated by isotonic replacement of Na+ with Li+, NMDG+, or Tris+. Concentration-response data revealed an EC50 in a physiologically relevant range for these animals of 5.1 +/- 0.9 mM (n = 11). In vertebrates, the betaine transporter is structurally related to the GABA transporter, and although GABA did not directly activate the betaine-induced current, it reversibly reduced betaine responses by 34 +/- 14% (n = 8). Short-term changes in osmolality alone did not activate the Cl- current, but when combined with betaine, Cl- currents increased in hypertonic solutions and decreased in hypotonic solutions. Activation of the betaine transporter and Cl- current in hypertonic conditions may affect both volume regulation and excitability in L. brevis motor neurons. This study is the first report of a novel betaine transporter in neurons that can act as a Cl- channel. PMID:10200192

Petty, C N; Lucero, M T

1999-04-01

220

Childhood Adversity, Serotonin Transporter (5-HTTLPR) Genotype, and Risk for Cigarette Smoking and Nicotine Dependence in Alcohol Dependent Adults  

PubMed Central

Background This study examined the extent to which cigarette smoking and nicotine dependence in adults with alcohol dependence (AD) are associated with adverse childhood experiences. Gender, social support, and an allelic variant in the gene encoding the serotonin transporter (5-HTTLPR) were examined as moderators of this relationship. Methods The Semi-Structured Assessment for the Genetics of Alcoholism- Version II (SSAGA-II) was used to assess DSM-IV diagnoses and cigarette smoking characteristics as well as traumatic life events and social support during childhood in 256 AD men (n=149) and women (n=107). Results An increase in number of adverse childhood events was associated with heightened risk of cigarette use and nicotine dependence. 5-HTTLPR genotype, gender, and social support did not significantly moderate the relationships among childhood adversity and ever-smoking or nicotine dependence. Conclusions Results extend previous findings to suggest that childhood adversity is strongly related to risk for ever-smoking and nicotine dependence in AD individuals. Additional research is needed to examine other potential genetic and environmental moderators and mediators of the relationships among smoking, alcohol use, and childhood trauma.

Mingione, Carolyn J.; Heffner, Jaimee L.; Blom, Thomas J.; Anthenelli, Robert M.

2011-01-01

221

Wave orbital velocity, fade, and SAR response to azimuth waves  

Microsoft Academic Search

Orbital motion of azimuth waves imposes differential Doppler shifts on wave imagery as seen by a SAR. This paper shows that these Doppler shifts are a function only of the wave and sensor geometry, and are not a function of SAR parameters. The azimuth wave reflectivity so modulated is equivalent to a redistributed scatterer density which can be used as

R. Raney

1981-01-01

222

Immunocytochemical Evidence of Tulp1-dependent Outer Segment Protein Transport Pathways in Photoreceptor Cells  

PubMed Central

Tulp1 is a protein of unknown function exclusive to rod and cone photoreceptor cells. Mutations in the gene cause autosomal recessive retinitis pigmentosa in humans and photoreceptor degeneration in mice. In tulp1?/? mice, rod and cone opsins are mislocalized, and rhodopsin-bearing extracellular vesicles accumulate around the inner segment, indicating that Tulp1 is involved in protein transport from the inner segment to the outer segment. To investigate this further, we sought to define which outer segment transport pathways are Tulp1-dependent. We used immunohistochemistry to examine the localization of outer segment proteins in tulp1?/? photoreceptors, prior to retinal degeneration. We also surveyed the condition of inner segment organelles and rhodopsin transport machinery proteins. Herein, we show that guanylate cyclase 1 and guanylate cyclase activating proteins 1 and 2 are mislocalized in the absence of Tulp1. Furthermore, arrestin does not translocate to the outer segment in response to light stimulation. Additionally, data from the tulp1?/? retina adds to the understanding of peripheral membrane protein transport, indicating that rhodopsin kinase and transducin do not co-transport in rhodopsin carrier vesicles and phosphodiesterase does not co-transport in guanylate cyclase carrier vesicles. These data implicate Tulp1 in the transport of selective integral membrane outer segment proteins and their associated proteins, specifically, the opsin and guanylate cyclase carrier pathways. The exact role of Tulp1 in outer segment protein transport remains elusive. However, without Tulp1, two rhodopsin transport machinery proteins exhibit abnormal distribution, Rab8 and Rab11, suggesting a role for Tulp1 in vesicular docking and fusion at the plasma membrane near the connecting cilium.

Grossman, Gregory H.; Watson, Rao F.; Pauer, Gayle J.T.; Bollinger, Kathryn; Hagstrom, Stephanie A.

2011-01-01

223

Temperature-dependent electron transport in ZnO micro/nanowires  

NASA Astrophysics Data System (ADS)

Temperature dependent electron transport properties of individual ZnO mirco/nanowires from 293 K to 473 K were investigated by a four-probe method, and the size dependence of activation energy was studied. The conductivity increased with the increasing temperature, which was attributed to the thermal activations of donors: shallow donors and deep donors. The activation energy related to shallow donors was effectively independent of the radius, suggesting that it was associated with the surface conduction channel of ZnO wire, while a nearly inverse dependence of the activation energy of deep donors on the wire diameter may result from the dielectric confinement effect.

Li, Xin; Qi, Junjie; Zhang, Qi; Zhang, Yue

2012-10-01

224

Dependence of seismic mean residuals on distance, azimuth and time  

Microsoft Academic Search

MOST studies on the changes of sesimic velocity which precede earthquakes (see, for example, refs 1-5) are based on data from highly sensitive, but local, seismic networks. Large earthquakes very rarely occur in the neighbourhoods of these networks, so to study velocity changes associated with earthquakes of large magnitude, it is better to use a worldwide network of stations such

A. G. Prozorov

1974-01-01

225

Beam energy dependence of azimuthal anisotropy at RHIC-PHENIX  

SciTech Connect

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.

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

2012-05-15

226

Twist-4 contributions to the azimuthal asymmetry in semi-inclusive deeply inelastic scattering  

SciTech Connect

We calculate the differential cross section for the unpolarized semi-inclusive deeply inelastic scattering process e{sup -}+N{yields}e{sup -}+q+X in leading order of perturbative QCD and up to twist-4 in power corrections and study, in particular, the azimuthal asymmetry . The final results are expressed in terms of transverse momentum dependent parton matrix elements of the target nucleon up to twist-4. We also apply it to e{sup -}+A{yields}e{sup -}+q+X and illustrate numerically the nuclear dependence of the azimuthal asymmetry by using a Gaussian ansatz for the transverse momentum dependent parton matrix elements.

Song Yukun; Liang Zuotang [School of Physics, Shandong University, Jinan, Shandong 250100 (China); Gao Jianhua [Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); Wang XinNian [Institute of Particle Physics, Huazhong Normal University, Wuhan 430079 (China); Nuclear Science Division, MS 70R0319, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)

2011-03-01

227

Diameter-dependent ion transport through the interior of isolated single-walled carbon nanotubes.  

PubMed

Nanopores that approach molecular dimensions demonstrate exotic transport behaviour and are theoretically predicted to display discontinuities in the diameter dependence of interior ion transport because of structuring of the internal fluid. No experimental study has been able to probe this diameter dependence in the 0.5-2?nm diameter regime. Here we observe a surprising fivefold enhancement of stochastic ion transport rates for single-walled carbon nanotube centered at a diameter of approximately 1.6?nm. An electrochemical transport model informed from literature simulations is used to understand the phenomenon. We also observe rates that scale with cation type as Li(+)>K(+)>Cs(+)>Na(+) and pore blocking extent as K(+)>Cs(+)>Na(+)>Li(+) potentially reflecting changes in hydration shell size. Across several ion types, the pore-blocking current and inverse dwell time are shown to scale linearly at low electric field. This work opens up new avenues in the study of transport effects at the nanoscale. PMID:24025921

Choi, Wonjoon; Ulissi, Zachary W; Shimizu, Steven F E; Bellisario, Darin O; Ellison, Mark D; Strano, Michael S

2013-09-12

228

Characterization of the ATP-dependent LTC4 transporter in cisplatin-resistant human KB cells.  

PubMed

An active efflux pump for cis-diamminedichloroplatinum(II) (cisplatin) has been identified in cisplatin-resistant KCP-4 cells isolated from human epidermoid carcinoma KB-3-1 cells. The adenosine triphosphate(ATP)-dependent transport of leukotriene C4 (LTC4), an endogenous substrate for the glutathione S-conjugate export pump(GS-X pump), has been found in membrane vesicles prepared from KCP-4 cells. Multidrug resistance-associated protein (MRP) has also been identified as an ATP-dependent LTC4 transporter. To examine whether the GS-X pump expressed in KCP-4 cells in MRP, we investigated the expression of MRP in KCP-4 cells and compared the LTC4 transporting activity of GS-X pump expressed in KCP-4 cells with that of MRP. The level of MRP gene expression in KCP-4 cells was low and similar to that in KB-3-1 cells. MRP was not detected in membrane vesicles prepared from KB-3-1 and KCP-4 cells by immunoblot analysis. The ATP-dependent transport of LTC4 in KCP-4 and C-A120 vesicles showed saturable kinetics with an apparent Km of 0.18 microM and 0.25 microM, respectively. [3H]LTC4 transport in KCP-4 vesicles was more inhibited by 2,4-dinitrophenyl-S-glutathione(DNP-SG), bis-(glutathionato)-platinum(II) (GS-platinum) complex and glutathione disulfide(GS-SG) and less by LTD4 compared with that in C-A120 vesicles. The character of the LTC4 transporter expressed in KCP-4 vesicles is similar but not identical to that of MRP. Our results suggest that a glutathione S-conjugate export pump which is different from MRP exists in cisplatin-resistant KCP-4 cells. PMID:8806607

Chuman, Y; Chen, Z S; Sumizawa, T; Furukawa, T; Haraguchi, M; Takebayashi, Y; Niwa, K; Yamada, K; Aikou, T; Akiyama, S

1996-09-01

229

MARK/PAR1 kinase is a regulator of microtubule-dependent transport in axons  

PubMed Central

Microtubule-dependent transport of vesicles and organelles appears saltatory because particles switch between periods of rest, random Brownian motion, and active transport. The transport can be regulated through motor proteins, cargo adaptors, or microtubule tracks. We report here a mechanism whereby microtubule associated proteins (MAPs) represent obstacles to motors which can be regulated by microtubule affinity regulating kinase (MARK)/Par-1, a family of kinases that is known for its involvement in establishing cell polarity and in phosphorylating tau protein during Alzheimer neurodegeneration. Expression of MARK causes the phosphorylation of MAPs at their KXGS motifs, thereby detaching MAPs from the microtubules and thus facilitating the transport of particles. This occurs without impairing the intrinsic activity of motors because the velocity during active movement remains unchanged. In primary retinal ganglion cells, transfection with tau leads to the inhibition of axonal transport of mitochondria, APP vesicles, and other cell components which leads to starvation of axons and vulnerability against stress. This transport inhibition can be rescued by phosphorylating tau with MARK.

Mandelkow, Eva-Maria; Thies, Edda; Trinczek, Bernhard; Biernat, Jacek; Mandelkow, Eckard

2004-01-01

230

Measurement of plasma current dependent changes in impurity transport and comparison with nonlinear gyrokinetic simulation  

SciTech Connect

Measured impurity transport coefficients are found to demonstrate a strong dependence on plasma current in the core of Alcator C-Mod. These measurements are compared directly with linear and nonlinear gyrokinetic simulation in an attempt to both qualitatively and quantitatively reproduce the measured impurity transport. Discharges constituting a scan of plasma current from 0.6 to 1.2 MA were performed during the 2010 run campaign. The impurity transport from these discharges was determined using a novel set of spectroscopic diagnostics available on Alcator C-Mod. This diagnostic suite allowed for the effective constraint of impurity transport coefficient profiles inside of r/a = 0.6. A decrease in the measured impurity diffusivity and inward convection is found with increased plasma current. Global, nonlinear gyrokinetic simulations were performed using the GYRO code [J. Candy and R. E. Waltz, J Comput. Phys. 186, 545 (2003)] for all discharges in the experimental scan and are found to reproduce the experimental trends, while demonstrating good quantitative agreement with measurement. A more comprehensive quantitative comparison was performed on the 0.8 MA discharge of the current scan which demonstrates that simultaneous agreement between experiment and simulation in both the impurity particle transport and ion heat transport channels is attainable within experimental uncertainties.

Howard, N. T.; Greenwald, M.; White, A. E.; Reinke, M. L.; Ernst, D.; Podpaly, Y. [MIT-Plasma Science and Fusion Center, Cambridge, Massachusetts 02139 (United States); Mikkelsen, D. R. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States); Candy, J. [General Atomics, San Diego, California 92186 (United States)

2012-05-15

231

Spin-dependent transport of electrons through ferromagnetic\\/insulator\\/semiconductor nanostructures  

Microsoft Academic Search

The model of spin-dependent electron transport through ferromagnetic\\/insulator\\/semiconductor nanostructures was developed on the basis of the transport equation accounting for carrier scattering and the image forces at the interfaces. Modeling was performed for Co\\/Al2O3\\/p-Si and CoFe\\/MgO\\/n-Si nanostructures. Tunneling magnetoresistance was modeled to be 7-13 % in Co\\/Al2O3\\/p-Si nanostructures biased in range from 0.7 to 2.0 V. A scattering well in

Tatiana N. Sidorova; Alexander L. Danilyuk; Vviktor E. Borisenko; F. Arnaud D'Avitaya; J.-L. Lazzari

2008-01-01

232

Mass transport equations unifying descriptions of isothermal diffusion, thermomigration, segregation, and position-dependent diffusivity  

NASA Astrophysics Data System (ADS)

Via the combined use of the jump frequency and chemical force formulation methods, a set of generalized mass transport equations has been derived. This set of equations unifies the descriptions of isothermal diffusion, thermomigration induced by a thermal gradient, and segregation and the position-dependent diffusivity arising from the crystal inhomogeneity. The equations reproduce Fick's laws for the isothermal homogeneous crystal case, and the diffusion-segregation equations for the isothermal inhomogeneous crystal case. Also, a new expression for the heat of transport of thermomigration is obtained.

Tan, T. Y.

1998-11-01

233

Spin-dependent transport through a quantum wire on a graphene surface  

NASA Astrophysics Data System (ADS)

Electron transport through a quantum wire coupled with ferromagnetic leads on a graphene sheet is studied by the Keldysh nonequilibrium Green's function method. We investigate the dependence of the transport properties on the wire-graphene coupling strength in detail. It is found that the peaks of the density of states fade away and the current is suppressed with the increasing wire-graphene coupling strength. The spin polarized strength of the two leads can effectively suppress the current and the transmission. The results obtained provide valuable theoretical guidance to the spintronics experiment.

Yang, Fu-Bin; Cheng, Yan; Liu, Fu-Ti; Chen, Xiang-Rong

2013-01-01

234

Time-Dependent View of Sequential Transport through Molecules with Rapidly Fluctuating Bridges  

NASA Astrophysics Data System (ADS)

Molecules in junctions often fluctuate considerably, especially when subject to the influence of solvent molecules. These fluctuations in site energies and couplings can be sampled, for example, by using molecular dynamics simulations, and can lead to incoherent effects in charge transport. To this end, a popular snapshot-averaged Landauer approach is compared to a time-dependent Green’s function scheme. Since sequential transport dominates in systems with rapidly varying bridges, schemes not taking the time order of conformations into account, such as the Landauer approach, are inappropriate.

Popescu, Bogdan; Woiczikowski, P. Benjamin; Elstner, Marcus; Kleinekathöfer, Ulrich

2012-10-01

235

The Insertion and Transport of Anandamide in Synthetic Lipid Membranes Are Both Cholesterol-Dependent  

PubMed Central

Background Anandamide is a lipid neurotransmitter which belongs to a class of molecules termed the endocannabinoids involved in multiple physiological functions. Anandamide is readily taken up into cells, but there is considerable controversy as to the nature of this transport process (passive diffusion through the lipid bilayer vs. involvement of putative proteic transporters). This issue is of major importance since anandamide transport through the plasma membrane is crucial for its biological activity and intracellular degradation. The aim of the present study was to evaluate the involvement of cholesterol in membrane uptake and transport of anandamide. Methodology/Principal Findings Molecular modeling simulations suggested that anandamide can adopt a shape that is remarkably complementary to cholesterol. Physicochemical studies showed that in the nanomolar concentration range, anandamide strongly interacted with cholesterol monolayers at the air-water interface. The specificity of this interaction was assessed by: i) the lack of activity of structurally related unsaturated fatty acids (oleic acid and arachidonic acid at 50 nM) on cholesterol monolayers, and ii) the weak insertion of anandamide into phosphatidylcholine or sphingomyelin monolayers. In agreement with these data, the presence of cholesterol in reconstituted planar lipid bilayers triggered the stable insertion of anandamide detected as an increase in bilayer capacitance. Kinetics transport studies showed that pure phosphatidylcholine bilayers were weakly permeable to anandamide. The incorporation of cholesterol in phosphatidylcholine bilayers dose-dependently stimulated the translocation of anandamide. Conclusions/Significance Our results demonstrate that cholesterol stimulates both the insertion of anandamide into synthetic lipid monolayers and bilayers, and its transport across bilayer membranes. In this respect, we suggest that besides putative anandamide protein-transporters, cholesterol could be an important component of the anandamide transport machinery. Finally, this study provides a mechanistic explanation for the key regulatory activity played by membrane cholesterol in the responsiveness of cells to anandamide.

Di Pasquale, Eric; Chahinian, Henri; Sanchez, Patrick; Fantini, Jacques

2009-01-01

236

Cyclic GMP-dependent Stimulation of Serotonin Transport Does Not Involve Direct Transporter Phosphorylation by cGMP-dependent Protein Kinase*  

PubMed Central

The serotonin transporter (SERT) is responsible for reuptake of serotonin (5-hydroxytryptamine) after its exocytotic release from neurons. It is the primary target for antidepressants and stimulants, including “ecstasy” (3,4-methylenedioxymethamphetamine). SERT is regulated by several processes, including a cyclic GMP signaling pathway involving nitric oxide synthase, guanylyl cyclase, and cGMP-dependent protein kinase (PKG). Here, we show that SERT was phosphorylated in a PKG I?-dependent manner in vitro, but that SERT was not a direct substrate of PKG. We generated an analog-sensitive gatekeeper residue mutant of PKG I? (M438G) that efficiently used the ATP analog N6-benzyl-ATP. This mutant, but not the wild type (WT) kinase, used the ATP analog to phosphorylate both a model peptide substrate as well as an established protein substrate of PKG (vasodilator-stimulated phosphoprotein). PKG I? M438G effectively substituted for the WT kinase in stimulating SERT-mediated 5-hydroxytryptamine transport in cultured cells. Addition of either WT or mutant PKG I? M438G to membranes containing SERT in vitro led to radiolabel incorporation from [?-33P]ATP but not from similarly labeled N6-benzyl-ATP, indicating that SERT was phosphorylated by another kinase that could not utilize the ATP analog. These results are consistent with the proposed SERT phosphorylation site, Thr-276, being highly divergent from the consensus PKG phosphorylation site sequence, which we verified through peptide library screening. Another proposed SERT kinase, the p38 mitogen-activated protein kinase, could not substitute for PKG in this assay, and p38 inhibitors did not block PKG-dependent phosphorylation of SERT. The results suggest that PKG initiates a kinase cascade that leads to phosphorylation of SERT by an as yet unidentified protein kinase.

Wong, Albert; Zhang, Yuan-Wei; Jeschke, Grace R.; Turk, Benjamin E.; Rudnick, Gary

2012-01-01

237

Selective up-regulation of the glial Na +-dependent glutamate transporter GLT1 by a neuroimmunophilin ligand results in neuroprotection  

Microsoft Academic Search

Excessive accumulation of extracellular glutamate results in neuronal death. Termination of synaptic glutamate transmission and the prevention of excitotoxicity depend on rapid removal of glutamate by high affinity Na+-dependent transporters. The astroglial transporter GLT1 is the predominant subtype, responsible for the bulk of extracellular clearance and for limiting excitotoxicity. This protein is crucial in the prevention of chronic glutamate neurotoxicity,

Raquelli Ganel; Tony Ho; Nicholas J. Maragakis; Mandy Jackson; Joseph P. Steiner; Jeffrey D. Rothstein

2006-01-01

238

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

SciTech Connect

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.

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

2011-06-20

239

Length and temperature dependent crossover of charge transport across molecular junctions  

NASA Astrophysics Data System (ADS)

We study the electronic transport in a molecular junction, in which each unit is coupled to a local phonon bath, using the non-equilibrium Green's function method. We observe the conductance oscillates with the molecular chain length and the oscillation period in odd-numbered chains depends strongly on the applied bias. This oscillatory behavior is smeared out at the bias voltage near the phonon energy. For the phonon-free case, we find a crossover from tunneling to thermally activated transport as the length of the molecule increases. In the presence of electron-phonon interaction, the transport is thermally driven and a crossover from the thermally suppressed to assisted conduction is observed.

Lo, Ya-Lin; Sun, Shih-Jye; Kao, Ying-Jer

2012-02-01

240

What do we learn from the scaling properties of azimuthal anisotropy measurements at RHIC and the LHC?  

NASA Astrophysics Data System (ADS)

Azimuthal anisotropy measurements are a key ingredient in ongoing efforts to pin down the precise value of the transport coefficients of the quark gluon plasma (QGP) produced in heavy ion collisions at both the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC). I will discuss the scaling properties of these measurements and demonstrate their utility as constraints for precision extraction of several transport coefficients.

Lacey, Roy

2013-04-01

241

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

PubMed Central

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.

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

2011-01-01

242

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)

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.

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

2013-07-01

243

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

NASA Astrophysics Data System (ADS)

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.

Murphy, J. R.; Haberle, R. M.; Toon, O. B.; Pollack, J. B.

1993-02-01

244

Transport coefficients of multi-particle collision algorithms with velocity-dependent collision rules  

NASA Astrophysics Data System (ADS)

Detailed calculations of the transport coefficients of a recently introduced particle-based model for fluid dynamics with a non-ideal equation of state are presented. Excluded volume interactions are modeled by means of biased stochastic multi-particle collisions which depend on the local velocities and densities. Momentum and energy are exactly conserved locally. A general scheme to derive transport coefficients for such biased, velocity-dependent collision rules is developed. Analytic expressions for the self-diffusion coefficient and the shear viscosity are obtained, and very good agreement is found with numerical results at small and large mean free paths. The viscosity turns out to be proportional to the square root of temperature, as in a real gas. In addition, the theoretical framework is applied to a two-component version of the model, and expressions for the viscosity and the difference in diffusion of the two species are given.

Ihle, Thomas

2008-06-01

245

Transport coefficients of multi-particle collision algorithms with velocity-dependent collision rules.  

PubMed

Detailed calculations of the transport coefficients of a recently introduced particle-based model for fluid dynamics with a non-ideal equation of state are presented. Excluded volume interactions are modeled by means of biased stochastic multi-particle collisions which depend on the local velocities and densities. Momentum and energy are exactly conserved locally. A general scheme to derive transport coefficients for such biased, velocity-dependent collision rules is developed. Analytic expressions for the self-diffusion coefficient and the shear viscosity are obtained, and very good agreement is found with numerical results at small and large mean free paths. The viscosity turns out to be proportional to the square root of temperature, as in a real gas. In addition, the theoretical framework is applied to a two-component version of the model, and expressions for the viscosity and the difference in diffusion of the two species are given. PMID:21694315

Ihle, Thomas

2008-05-06

246

Symmetry-dependent transport properties and bipolar spin filtering in zigzag ?-graphyne nanoribbons  

NASA Astrophysics Data System (ADS)

First-principles calculations are performed to investigate the transport properties of zigzag ?-graphyne nanoribbons (Z?GNRs). It is found that asymmetric Z?GNRs behave as conductors with linear current-voltage relationships, whereas symmetric Z?GNRs have very small currents under finite bias voltages, similar to those of zigzag graphene nanoribbons. The symmetry-dependent transport properties arise from different coupling rules between the ? and ?* subbands around the Fermi level, which are dependent on the wave-function symmetry of the two subbands. Based on the coupling rules, we further demonstrate the bipolar spin-filtering effect in the symmetric Z?GNRs. It is shown that nearly 100% spin-polarized current can be produced and modulated by the direction of bias voltage and/or magnetization configuration of the electrodes. Moreover, the magnetoresistance effect with the order larger than 500000% is also predicted. Our calculations suggest Z?GNRs as a promising candidate material for spintronics.

Yue, Qu; Chang, Shengli; Tan, Jichun; Qin, Shiqiao; Kang, Jun; Li, Jingbo

2012-12-01

247

Influence of anisotropic scattering on the size of time-dependent systems in monoenergetic neutron transport  

NASA Astrophysics Data System (ADS)

Criticality type eigenvalues of the one-speed transport equation in a homogeneous slab with anisotropic scattering and Marshak boundary conditions are considered. The connection between the transport equations for a critical and for a time-decaying system is established, and thus the time-dependent equation is reduced to the stationary one. Variation of the size of the time-dependent system with anisotropic scattering is studied numerically. Calculations for different combinations of the scattering parameters and the selected values of the time decay constant using the 0022-3727/32/3/020/img1 method are reported. Results are discussed and compared with those already obtained using various methods available in the literature.

Yildiz, Cemal

1999-02-01

248

Time-dependent 2-D modeling of edge plasma transport with high intermittency due to blobs  

NASA Astrophysics Data System (ADS)

Edge plasma transport is well known to be highly intermittent and non-diffusive via coherent structures (so-called blobs and ELM filaments) moving ballistically to walls. This intermittent transport has strong impact on both edge plasma parameters and plasma-wall interactions. The ``macro-blob'' approach to simulate simultaneously the edge plasma transport, statistical turbulent properties, impurities, and wall dynamics within the framework of 2-D edge-plasma fluid transport code has been developed and implemented into UEDGE. The results of time-dependent modeling of bursty plasma and wall responses with the improved UEDGE will be presented. The effect of a sequence of macro-blobs on background plasma profiles, on hydrogen radiation and recycling, and on particle and energy fluxes will be discussed. Impurity dynamics with macro-blobs is also presented showing the enhancement of sputtering rates, alteration of charge state profiles (caused by enhanced outward transport of high states and simultaneous advancement of low states toward the core), and change in erosion/deposition patterns. Work supported by DOE grant DE-FG02-04ER54739 at UCSD and DE-AC52-07NA27344 at LLNL.

Pigarov, A. Yu.; Krasheninnikov, S. I.; Rognlien, T. D.

2011-11-01

249

The opt1 gene of Drosophila melanogaster encodes a proton-dependent dipeptide transporter.  

PubMed

We have cloned and characterized the opt1 gene of Drosophila melanogaster. This gene encodes a protein with significant similarity to the PTR family of oligopeptide transporters. The OPT1 protein is localized to the apical epithelial membrane domains of the midgut, rectum, and female reproductive tract. The opt1 message is maternally loaded into developing oocytes, and OPT1 is found in the alpha-yolk spheres of the developing embryo. It is also found throughout the neuropil of the central nervous system, with elevated expression within the alpha- and beta-lobes of the mushroom bodies. Transport activity was examined in HeLa cells transiently expressing OPT1. This protein is a high-affinity transporter of alanylalanine; the approximate Km constant is 48.8 microM for this substrate. OPT1 dipeptide transport activity is proton dependent. The ability of selected beta-lactams to inhibit alanylalanine transport suggests that OPT1 has a broad specificity in amino acid side chains and has a substrate requirement for an alpha-amino group. Together these data suggest an important role for OPT1 in regulating amino acid availability. PMID:9730971

Roman, G; Meller, V; Wu, K H; Davis, R L

1998-09-01

250

Cathode Work Function Dependence of Electron Transport Efficiency through Buffer Layer in Organic Solar Cells  

NASA Astrophysics Data System (ADS)

An electron transport mechanism through a cathode buffer layer of organic solar cells is experimentally investigated. Inverted organic solar cells with the structure of indium--tin oxide (ITO)/thin cathode metal/bathocuproine (BCP)/fullerene (C60)/copper phthalocyanine (CuPc)/pentacene/Ag (anode) are examined. A new model, in that electrons are transported across the BCP buffer layer not through defect states but over the lowest unoccupied molecular orbital (LUMO), is proposed. That is, the defect state density in the BCP layer is not important for electron transport, though the hopping transport model via the defect states is widely accepted. The transport efficiency is sensitive to the cathode work function (\\mathit{WF}C). As \\mathit{WF}C decreases, the energy difference between the BCP LUMO and the cathode Fermi level decreases. This introduces a low electronic potential barrier height from the cathode to the acceptor. The low \\mathit{WF}C is thus important to achieve a low series resistance. Furthermore, the dependence of \\mathit{WF}C on barrier height is also confirmed for tris(8-hydroxyquinolinato)aluminum buffer.

Oida, Tatsuya; Harafuji, Kenji

2012-09-01

251

Mass and Magnetic Field Dependence of Electrostatic Particle Transport and Turbulence in LAPD-U  

NASA Astrophysics Data System (ADS)

The scaling of particle transport with ion mass and magnetic field strength remains an open question in plasma research. Direct comparison of experiment with theory is often complicated by inability to significantly vary critical parameters such as ion mass, pressure gradient, ion gyro-radius, etc. The LAPD-U magnetized, linear plasma at UCLA provides the ideal platform for such studies, allowing large parameter variation. The magnetic field in LAPD-U can be varied over a range of 500 - 1500 G, while ion species can be varied to change mass by a factor of at least 10. In addition, ion gyro-radii are small compared to the plasma diameter ( 1 m). Cross-field transport in LAPD-U is thought to be caused by electrostatic turbulence, also a leading candidate for transport in fusion plasmas. It is planned, therefore, to investigate turbulence and transport characteristics as a function of parameter space. In particular, measurement of the mass and magnetic field dependence of electrostatic particle transport and turbulence characteristics in LAPD-U will be presented.

Crocker, N. A.; Gilmore, M.; Peebles, W. A.; Will, S.; Nguyen, X. V.; Carter, T. A.

2003-10-01

252

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

SciTech Connect

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.

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

253

Numerical Modeling of Contaminant Transport with Spatially-Dependent Dispersion and Non-Linear Chemical Reaction  

Microsoft Academic Search

A one-dimensional advective-dispersive contaminant transport model with scale-dependent dispersion coefficient in the presence of a nonlinea r chemical reaction of arbitrary order is considered. Two types of variations of the dispersion coefficient with the downstream distance are considered. The first type assumes that the d ispersivity increases as a polynomial function with distance while the other assumes an exponentially- increasing

A. J. Chamkha

2007-01-01

254

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

Microsoft Academic Search

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

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

1999-01-01

255

Binding protein dependent transport of glycine betaine and its osmotic regulation in Escherichia coli K12  

Microsoft Academic Search

Glycine betaine, which functions as an osmoprotectant, is accumulated to high intracellular concentrations in Escherichia coli at high osmolarity. We demonstrate the presence of a high-affinity, binding protein dependent transport system for glycine betaine, which is encoded by the proU region. We show the osmotically regulated synthesis of a 32 kDa periplasmic protein that is a glycine betaine binding protein

Gerhard May; Elke Faatz; Merna Villarejo; Erhard Bremer

1986-01-01

256

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

Microsoft Academic Search

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

Takuya Kobayashi; Takashi Murayama

2009-01-01

257

Vertical heat transports in the ocean and their effect on time-dependent climate change  

Microsoft Academic Search

In response to increasing atmospheric concentrations of greenhouse gases, the rate of time-dependent climate change is determined\\u000a jointly by the strength of climate feedbacks and the efficiency of processes which remove heat from the surface into the deep\\u000a ocean. This work examines the vertical heat transport processes in the ocean of the HADCM2 atmosphere–ocean general circulation\\u000a model (AOGCM) in experiments

J. M. Gregory

2000-01-01

258

Numerically exact, time-dependent study of correlated electron transport in model molecular junctions  

NASA Astrophysics Data System (ADS)

The multilayer multiconfiguration time-dependent Hartree theory within second quantization representation of the Fock space is applied to study correlated electron transport in models of single-molecule junctions. Extending previous work, we consider models which include both electron-electron and electronic-vibrational interaction. The results show the influence of the interactions on the transient and the stationary electrical current. The underlying physical mechanisms are analyzed in conjunction with the nonequilibrium electronic population of the molecular bridge.

Wang, Haobin; Thoss, Michael

2013-04-01

259

Differential Regulation of Mouse Kidney Sodium-Dependent Transporters mRNA by Cadmium  

Microsoft Academic Search

Chronic exposure to cadmium can result in renal glycosuria. Previously, we reported that cadmium reduced the relative abundance of the sodium-glucose cotransporter mRNA (Blumenthal et al., Toxicol. Appl. Pharmacol.149, 49–54, 1998). To investigate this phenomenon further, we isolated full-length cDNA clones encoding both high- and low-affinity sodium-dependent glucose transporters SGLT1 and SGLT2, respectively, from cultured mouse kidney cortical cells. We

Niloofar M. Tabatabai; Samuel S. Blumenthal; Donna L. Lewand; David H. Petering

2001-01-01

260

Sodium-Dependent Amino Acid Transport Is Preserved in Lyophilized Reconstituted Apical Membranes from Intestinal Epithelium  

Microsoft Academic Search

We demonstrate for the first time that functional electrogenic Na+-dependent amino acid transport is preserved for extended periods when purified brush border membranes prepared in hypotonic media are lyophilized and then rehydrated in buffer containing mannitol, NaSCN, and\\/or KSCN\\/valinomycin. Reconstituted lyophilized apical membranes from small intestine formed morphologically, physiologically, and thermodynamically normal vesicles which transportedl-alanine via system B into an

Bruce R. Stevens; Robert L. Preston

1998-01-01

261

Sodium-dependent norepinephrine-induced currents in norepinephrine-transporter-transfected HEK-293 cells blocked by cocaine and antidepressants.  

PubMed

Transport of norepinephrine (NE+) by cocaine- and antidepressant-sensitive transporters in presynaptic terminals is predicted to involve the cotransport of Na+ and Cl-, resulting in a net movement of charge per transport cycle. To explore the relationship between catecholamine transport and ion permeation through the NE transporter, we established a human norepinephrine transporter (hNET) cell line suitable for biochemical analysis and patch-clamp recording. Stable transfection of hNET cDNA into HEK-293 (human embryonic kidney) cells results in lines exhibiting (1) a high number of transporter copies per cell (10(6)), as detected by radioligand binding and hNET-specific antibodies, (2) high-affinity, Na(+)-dependent transport of NE, and (3) inhibitor sensitivities similar to those of native membranes. Whole-cell voltage-clamp of hNET-293 cells reveals NE-induced, Na(+)-dependent currents blocked by antidepressants and cocaine that are absent in parental cells. In addition to NE-dependent currents, transfected cells posses an NE-independent mode of charge movement mediated by hNET. hNET antagonists without effect in non-transfected cells abolish both NE-dependent and NE-independent modes of charge movement in transfected cells. The magnitude of NE-dependent currents in these cells exceeds the expectations of simple carrier models using previous estimates of transport rates. To explain our observations, we propose that hNETs function as ion-gated ligand channels with an indefinite stoichiometry relating ion flux to NE transport. In this view, external Na+ and NE bind to the transporter with finite affinities in a cooperative fashion. However, coupled transport may not predict the magnitude or the kinetics of the total current through the transporter. We propose instead that Na+ gates NE transport and also the parallel inward flux of an indeterminate number of ions through a channel-like pore. PMID:7500004

Galli, A; DeFelice, L J; Duke, B J; Moore, K R; Blakely, R D

1995-10-01

262

pH-Dependent regulation of electron transport and ATP synthesis in chloroplasts.  

PubMed

This review is focused on pH-dependent mechanisms of regulation of photosynthetic electron transport and ATP synthesis in chloroplasts. The light-induced acidification of the thylakoid lumen is known to decelerate the plastoquinol oxidation by the cytochrome b 6 f complex, thus impeding the electron flow between photosystem II and photosystem I. Acidification of the lumen also triggers the dissipation of excess energy in the light-harvesting antenna of photosystem II, thereby protecting the photosynthetic apparatus against a solar stress. After brief description of structural and functional organization of the chloroplast electron transport chain, our attention is focused on the nature of the rate-limiting step of electron transfer between photosystem II and photosystem I. In the context of pH-dependent mechanism of photosynthetic control in chloroplasts, the mechanisms of plastoquinol oxidation by the cytochrome b 6 f complex have been considered. The light-induced alkalization of stroma is another factor of pH-dependent regulation of electron transport in chloroplasts. Alkalization of stroma induces activation of the Bassham-Benson-Calvin cycle reactions, thereby promoting efflux of electrons from photosystem I to NADP(+). The mechanisms of the light-induced activation of ATP synthase are briefly considered. PMID:23695653

Tikhonov, Alexander N

2013-05-22

263

ATP-dependent calcium transport across basal plasma membranes of human placental trophoblast  

SciTech Connect

As a first step in understanding the cellular basis of maternal-fetal calcium transfer, the authors examined the characteristics of calcium uptake by a highly purified preparation of the syncytiotrophoblast basal (fetal facing) plasma membrane. In the presence of nanomolar concentrations of free calcium, basal membranes demonstrated substantial ATP-dependent calcium uptake. This uptake required magnesium, was not significantly affected by Na/sup +/ or K/sup +/ (50 mM), or sodium azide (10 mM). Intravesicular calcium was rapidly and completely released by the calcium ionophore rapidly and completely released by the calcium ionophore A23187. Calcium transport was significantly stimulated by the calcium-dependent regulatory protein calmodulin. Placental membrane fractions enriched in endoplasmic reticulum (ER) and mitochondria also demonstrated ATP-dependent calcium uptake. In contrast to basal membrane, mitochondrial calcium uptake was completely inhibited by azide. The rate of calcium uptake was completely inhibited by azide. The rate of calcium uptake by the ER was only 20% of that of basal membranes. They conclude that the placental basal plasma membrane possesses a high-affinity calcium transport system similar to that found in plasma membranes of a variety of cell types. This transporter is situated to permit it to function in vivo in maternal-fetal calcium transfer.

Fisher, G.J.; Kelley, L.K.; Smith, C.H.

1987-01-01

264

EPR study of electron transport in the cyanobacterium Synechocystis sp. PCC 6803: Oxygen-dependent interrelations between photosynthetic and respiratory electron transport chains  

Microsoft Academic Search

In this work, we investigated electron transport processes in the cyanobacterium Synechocystis sp. PCC 6803, with a special emphasis focused on oxygen-dependent interrelations between photosynthetic and respiratory electron transport chains. Redox transients of the photosystem I primary donor P700 and oxygen exchange processes were measured by the EPR method under the same experimental conditions. To discriminate between the factors controlling

Boris V. Trubitsin; Vasilii V. Ptushenko; Olga A. Koksharova; Mahir D. Mamedov; Liya A. Vitukhnovskaya; Igor A. Grigor'ev; Alexey Yu. Semenov; Alexander N. Tikhonov

2005-01-01

265

Gestational age-dependent changes in gene expression of metabolic enzymes and transporters in pregnant mice.  

PubMed

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

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

2012-11-21

266

Cholate Resistance in Lactococcus lactis Is Mediated by an ATP-Dependent Multispecific Organic Anion Transporter  

PubMed Central

The cholate-resistant Lactococcus lactis strain C41-2, derived from wild-type L. lactis MG1363 through selection for growth on cholate-containing medium, displayed a reduced accumulation of cholate due to an enhanced active efflux. However, L. lactis C41-2 was not cross resistant to deoxycholate or cationic drugs, such as ethidium and rhodamine 6G, which are typical substrates of the multidrug transporters LmrP and LmrA in L. lactis MG1363. The cholate efflux activity in L. lactis C41-2 was not affected by the presence of valinomycin plus nigericin, which dissipated the proton motive force. In contrast, cholate efflux in L. lactis C41-2 was inhibited by ortho-vanadate, an inhibitor of P-type ATPases and ATP-binding cassette transporters. Besides ATP-dependent drug extrusion by LmrA, two other ATP-dependent efflux activities have previously been detected in L. lactis, one for the artificial pH probe 2?,7?-bis-(2-carboxyethyl)-5(and 6)-carboxyfluorescein (BCECF) and the other for the artificial pH probe N-(fluorescein thio-ureanyl)-glutamate (FTUG). Surprisingly, the efflux rate of BCECF, but not that of FTUG, was significantly enhanced in L. lactis C41-2. Further experiments with L. lactis C41-2 cells and inside out membrane vesicles revealed that cholate and BCECF inhibit the transport of each other. These data demonstrate the role of an ATP-dependent multispecific organic anion transporter in cholate resistance in L. lactis.

Yokota, Atsushi; Veenstra, Marloes; Kurdi, Peter; van Veen, Hendrik W.; Konings, Wil N.

2000-01-01

267

AtCCX3 is an Arabidopsis endomembrane H+ -dependent K+ transporter.  

PubMed

The Arabidopsis (Arabidopsis thaliana) cation calcium exchangers (CCXs) were recently identified as a subfamily of cation transporters; however, no plant CCXs have been functionally characterized. Here, we show that Arabidopsis AtCCX3 (At3g14070) and AtCCX4 (At1g54115) can suppress yeast mutants defective in Na(+), K(+), and Mn(2+) transport. We also report high-capacity uptake of (86)Rb(+) in tonoplast-enriched vesicles from yeast expressing AtCCX3. Cation competition studies showed inhibition of (86)Rb(+) uptake in AtCCX3 cells by excess Na(+), K(+), and Mn(2+). Functional epitope-tagged AtCCX3 fusion proteins were localized to endomembranes in plants and yeast. In Arabidopsis, AtCCX3 is primarily expressed in flowers, while AtCCX4 is expressed throughout the plant. Quantitative polymerase chain reaction showed that expression of AtCCX3 increased in plants treated with NaCl, KCl, and MnCl(2). Insertional mutant lines of AtCCX3 and AtCCX4 displayed no apparent growth defects; however, overexpression of AtCCX3 caused increased Na(+) accumulation and increased (86)Rb(+) transport. Uptake of (86)Rb(+) increased in tonoplast-enriched membranes isolated from Arabidopsis lines expressing CCX3 driven by the cauliflower mosaic virus 35S promoter. Overexpression of AtCCX3 in tobacco (Nicotiana tabacum) produced lesions in the leaves, stunted growth, and resulted in the accumulation of higher levels of numerous cations. In summary, these findings suggest that AtCCX3 is an endomembrane-localized H(+)-dependent K(+) transporter with apparent Na(+) and Mn(2+) transport properties distinct from those of previously characterized plant transporters. PMID:18775974

Morris, Jay; Tian, Hui; Park, Sunghun; Sreevidya, Coimbatore S; Ward, John M; Hirschi, Kendal D

2008-09-05

268

Test and Evaluation of Improved Azimuth Pulse Generator (Apg).  

National Technical Information Service (NTIS)

Azimuth pulse generators and a digital-to-synchro converter were subjected to tests at the National Aviation Facilities Experimental Center to ascertain their compliance with engineering requirements and to determine their performance in supplying antenna...

O. D. Carlson

1970-01-01

269

Determining an Azimuth with a North Seeking Gyro.  

National Technical Information Service (NTIS)

Surveyors frequently require an independent means of determining an azimuth. Traditional methods, a magnetic compass reading or stellar observation, suffer from limitations of accuracy or availability. Another possibility is the use of the North Seeking G...

K. P. Logan

1985-01-01

270

Using variable-frequency asymmetries to probe the magnetic field dependence of radial transport in a Malmberg-Penning trap  

SciTech Connect

A new experimental technique is used to study the dependence of asymmetry-induced radial particle flux {gamma} on axial magnetic field B in a modified Malmberg-Penning trap. This dependence is complicated by the fact that B enters the physics in at least two places: in the asymmetry-induced first order radial drift velocity v{sub r} = E{sub {theta}}/B and in the zeroth order azimuthal drift velocity v{sub {theta}} = E{sub r}/B. To separate these, we employ the hypothesis that the latter always enters the physics in the combination {omega}-l{omega}{sub R}, where {omega}{sub R} = v{sub {theta}}/r is the column rotation frequency and {omega} and l are the asymmetry frequency and azimuthal mode number, respectively. Points where {omega}-l{omega}{sub R} = 0 are then selected from a {gamma} vs r vs {omega} data set, thus insuring that any function of this combination is constant. When the selected flux {gamma}{sub sel} is plotted versus the density gradient, a roughly linear dependence is observed, showing that this selected flux is diffusive. This linear dependence is roughly independent of the bias of the center wire in our trap {phi}{sub cw}. Since in our experiment {omega}{sub R} is proportional to {phi}{sub cw}, this latter point shows that our technique has successfully removed any dependence on {omega}{sub R} and its derivatives, thus confirming our hypothesis. The slope of a least-squares fitted line through the {gamma}{sub sel} vs density gradient data then gives the diffusion coefficient D{sub 0} under the condition {omega}-l{omega}{sub R} = 0. Varying the magnetic field, we find D{sub 0} is proportional to B{sup -1.33{+-}}{sup 0.05}, a scaling that does not match any theory we know. These findings are then used to constrain the form of the empirical flux equation. It may be possible to extend this technique to give the functional dependence of the flux on {omega}-l{omega}{sub R}.

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

2009-03-30

271

Temperature dependence of ion and water transport in perfluorinated ionomer membranes for fuel cells.  

PubMed

To clarify the mechanisms of transport of ions and water molecules in perfluorosulfonated ionomer membranes for fuel cells, the temperature dependence of their transport behaviors was investigated in detail. Two types of Flemion membranes having different equivalent weight values (EW) were utilized along with Nafion 117 as the perfluorinated ionomer membranes, and H-, Li-, and Na-form samples were prepared for each membrane by immersion in 0.03 M HCl, LiCl, and NaCl aqueous solutions, respectively. The ionic conductivity, water self-diffusion coefficient (D(H)(2)(O)), and DSC were measured in the fully hydrated state as a function of temperature. The ionic conductivity of the membranes was reflected by the cation transport through the intermediary of water. Clearly, H(+) transports by the Grotthuss (hopping) mechanism, and Li(+) and Na(+) transport by the vehicle mechanism. The differences of the ion transport mechanisms were observed in the activation energies through the Arrhenius plots. The D(H)(2)(O) in the membranes exhibited a tendency similar to the ionic conductivity for the cation species and the EW value. However, no remarkable difference of D(H)(2)(O) between H- and the other cation-form membranes was observed as compared with the ionic conductivity. It indicates that water in each membrane diffuses almost in a similar way; however, H(+) transports by the Grotthuss mechanism so that conductivity of H(+) is much higher than that of the other cations. Moreover, the D(H)(2)(O) and DSC curves showed that a part of water in the membranes freezes around -20 degrees C, but the nonfreezing water remains and diffuses below that temperature. This fact suggests that completely free water (bulk water) does not exist in the membranes, and water weakly interacting with the cation species and the sulfonic acid groups in secondary and higher hydration shells freezes around -20 degrees C, while strongly binding water in primary hydration shells does not freeze. The ratio of freezing and nonfreezing water was estimated from the DSC curves. The D(H)(2)(O) in the membranes was found to be influenced by the ratio of freezing and nonfreezing water. DFT calculation of the interaction (solvation) energy between the cation species and water molecules suggested that the water content and the ratio of freezing and nonfreezing water depend strongly on the cation species penetrated into the membrane. PMID:16851330

Saito, Morihiro; Hayamizu, Kikuko; Okada, Tatsuhiro

2005-03-01

272

Azimuth and elevation direction finding using arbitrary array geometries  

Microsoft Academic Search

An ESPRIT-based algorithm is proposed to estimate the azimuth and elevation angles of multiple independent sources. The algorithm uses cumulants and imposes no geometric constraint on the array. Only one third of the hardware is needed for our algorithm as compared with covariance-based two-dimensional (2-D) ESPRIT. Our algorithm can estimate azimuth and elevation angles of M-1 sources using M sensors.

Tsung-Hsien Liu; Jerry M. Mendel

1998-01-01

273

Time-dependent 3-D dterministic transport on parallel architectures using Dantsys/MPI  

SciTech Connect

In addition to the ability to solve the static transport equation, we have also incorporated time dependence into our parallel 3-D S{sub {ital N}} code DANTSYS/MPI. Using a semi-implicit scheme, DANTSYS/MPI is capable of performing time-dependent calculations for both fissioning and pure source driven problems. We have applied this to various types of problems such as nuclear well logging and prompt fission experiments. This paper describes the form of the time- dependent equations implemented, their solution strategies in DANTSYS/MPI including iteration acceleration, and the strategies used for time-step control. Results are presented for a model nuclear well logging calculation.

Baker, R.S.; Alcouffe, R.E.

1996-12-31

274

Time-dependent transport of field-aligned bursts of electrons in flickering aurora  

NASA Astrophysics Data System (ADS)

We have developed a time-dependent auroral electron transport model to study emission rates caused by field-aligned bursts of electrons (FABs) seen in flickering aurora. We simulate flickering FABs by turning on and off a downward electron intensity distribution at a given frequency. We assume this electron beam originates and is modulated at an altitude of 4000 km. We apply collisionless transport from 4000 to 600 km and solve a time-dependent Boltzmann equation below 600 km. Because FABs have significant flux over a large energy range, dispersion has the most important effect on the resulting emission rates. We find that for a 5 Hz flickering FAB, the column emission rate varies 93% from peak to valley, whereas for 100 Hz flickering, the variation in column emission rate is only 12% from peak to valley. This variation is dependent on the frequency and source altitude. We show that with a time-dependent transport calculation and a filtered fast photometer or imager looking in the zenith, it is possible to obtain an upper limit on the altitude from which the optical flickering originates. We also study what electron detectors on a rocket or satellite might measure in the lower ionosphere when there exists field-aligned bursts of electrons. Velocity dispersion calculations will give source altitudes much lower than is correct if they are derived from low energy electrons (<2 keV) measured at altitudes below 150 km. Our results agree with the interpretation that field-aligned bursts are a temporal rather than spatial feature, and from this knowledge it should be possible to reconstruct the initial electron distribution function at the source altitude.

Peticolas, L.; Lummerzheim, D.

2000-06-01

275

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

SciTech Connect

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.

Casalderrey-Solana, Jorge; Wang, Xin-Nian

2007-06-24

276

CRM1-Dependent Transport Supports Cytoplasmic Accumulation of Adenoviral Early Transcripts  

PubMed Central

The life cycle of adenoviruses is divided by convention into early and late phases, separated by the onset of viral genome replication. Early events include virus adsorption, transport of the genome into the nucleus, and the expression of early genes. After the onset of viral DNA replication, transcription of the major late transcription unit (MLTU) and thereby synthesis of late proteins is induced. These steps are controlled by an orchestra of regulatory processes and require import of the genome and numerous viral proteins into the nucleus, as well as active transport of viral transcripts and proteins from the nucleus to the cytoplasm. The latter is achieved by exploiting the shuttling functions of cellular transport receptors, which normally stimulate the nuclear export of cellular mRNA and protein cargos. A set of adenoviral early and late proteins contains a leucine-rich nuclear export signal of the HIV-1 Rev type, known to be recognized by the cellular export receptor CRM1. However, a role for CRM1-dependent export in supporting adenoviral replication has not been established. To address this issue in detail, we investigated the impact of two different CRM1 inhibitors on several steps of the adenoviral life cycle. Inhibition of CRM1 led to a reduction in viral early and late gene expression, viral genome replication, and progeny virus production. For the first time, our findings indicate that CRM1-dependent shuttling is required for the efficient export of adenoviral early mRNA.

Schmid, Melanie; Gonzalez, Ramon A.

2012-01-01

277

Time-dependent Radial Transport of Electron Distributions Due to ECCD in DIII-D  

NASA Astrophysics Data System (ADS)

The radial transport modeling capability in the CQL3D bounce-averaged Fokker-Planck collisional-rf quasilinear code[1] has been greatly improved and the self-consistent time-dependent toroidal electric field added, making the code truly a ``Fokker-Planck-Transport'' code. The time-dependent, coupled 3D Fokker-Planck equation and the Ampere-Faraday Law equation are solved for the electron distribution, f( u,?u,?,t ), and the toroidal loop voltage, Vloop( ?,t ). A fully 3D, time-implicit solution of the FP equation using sparse-matrix methods[2] is coupled to a new iterative toroidal electric field solve. The DIII-D ECH experiment is in an intermediate driven regime with ?transport ?slowing[3] for the EC driven electrons. Results will be reported for time-evolution of radial profiles of current density, fast electrons, and toroidal loop voltage due to EC heating and current drive in DIII-D. [1] R.W. Harvey and M.G. McCoy, IAEA TCM on Advances in Simulation and Modeling of Thermonuclear Plasmas, Montreal, 1992; USDOC NTIS No. 93002962. [2] Y. Peysson et al., Radio Frequency Power in Plasmas, 15th Topical Conference, Moran, Wyoming (2003). [3] R.W. Harvey et al., Phys. Rev. Lett. 88, 205001 (2002).

Harvey, R. W.; Smirnov, A. P.; Prater, R.; Petty, C. C.

2007-11-01

278

Numerically exact, time-dependent treatment of vibrationally coupled electron transport in single-molecule junctions  

NASA Astrophysics Data System (ADS)

The multilayer multiconfiguration time-dependent Hartree (ML-MCTDH) theory within second quantization representation of the Fock space, a novel numerically exact methodology to treat many-body quantum dynamics for systems containing identical particles, is applied to study the effect of vibrational motion on electron transport in a generic model for single-molecule junctions. The results demonstrate the importance of electronic-vibrational coupling for the transport characteristics. For situations where the energy of the bridge state is located close to the Fermi energy, the simulations show the time-dependent formation of a polaron state that results in a pronounced suppression of the current corresponding to the phenomenon of phonon blockade. We show that this phenomenon cannot be explained solely by the polaron shift of the energy but requires methods that incorporate the dynamical effect of the vibrations on the transport. The accurate results obtained with the ML-MCTDH in this parameter regime are compared to results of nonequilibrium Green's function theory.

Wang, Haobin; Pshenichnyuk, Ivan; Härtle, Rainer; Thoss, Michael

2011-12-01

279

Transverse-momentum-dependent parton distribution function and jet transport in a nuclear medium  

SciTech Connect

We show that the gauge-invariant transverse-momentum-dependent (TMD) quark distribution function can be expressed as a sum of all higher-twist collinear parton matrix elements in terms of a transport operator. From such a general expression, we derive the nuclear broadening of the transverse-momentum distribution. Under the maximal two-gluon correlation approximation, in which all higher-twist nuclear multiple parton correlations with the leading nuclear enhancement are given by products of twist-two nucleon parton distributions, we find the nuclear transverse-momentum distribution as a convolution of a Gaussian distribution and the nucleon TMD quark distribution. The width of the Gaussian, or the mean total transverse-momentum broadening squared, is given by the path integral of the quark transport parameter q-circumflex{sub F} which can also be expressed in a gauge-invariant form and is given by the gluon distribution density in the nuclear medium. We further show that contributions from higher-twist nucleon gluon distributions can be resummed under the extended adjoint two-gluon correlation approximation and the nuclear transverse-momentum distribution can be expressed in terms of a transverse-scale-dependent quark transport parameter or gluon distribution density. We extend the study to hot medium and compare to dipole model approximation and N=4 supersymmetric Yang-Mills (SYM) theory in the strong coupling limit. We find that multiple gluon correlations become important in the strongly coupled system such as N=4 SYM plasma.

Liang Zuotang [Department of Physics, Shandong University, Jinan, Shandong 250100 (China); Wang Xinnian [Nuclear Science Division, MS 70R0319, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Zhou Jian [Department of Physics, Shandong University, Jinan Shandong 250100 (China); Nuclear Science Division, MS 70R0319, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States)

2008-06-15

280

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

NASA Astrophysics Data System (ADS)

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.

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

1999-11-01

281

Reconstitution and characterization of ATP-dependent bile acid transport in human and rat placenta.  

PubMed Central

Bile acid (BA) transport across the human microvillus maternal-facing trophoblast plasma membrane (mTPM) has been recently reported to be stimulated by the presence of ATP [Marin, Bravo, El-Mir and Serrano (1993) J. Hepatol. 18, S41]. Reconstitution of BA transport activity in proteoliposomes from human mTPM is reported in this paper. Typical characteristics of BA transport in native mTPM vesicles, including a requirement for ATP hydrolysis and inhibition by other BA species, were preserved in proteoliposome preparations. BA transport into 20- and 14-day-gestation rat mTPM vesicles was also stimulated by the presence of ATP as noted in human mTPM and in the rat liver canalicular membrane. Besides this functional similarity, these ATP-dependent carriers may share structural characteristics, as demonstrated by studies using an antibody (100 Ab) raised against the 100 kDa BA carrier of the canalicular membrane from rat liver which recognized proteins in both human and rat brush-border trophoblast membranes. Images Figure 2

Bravo, P; Marin, J J; Beveridge, M J; Novak, D A

1995-01-01

282

Strain dependence of transport nonuniversality in disordered conductor-insulator composites  

NASA Astrophysics Data System (ADS)

A vast class of disordered conducting-insulating compounds close to the percolation thresold is characterized by nonuniversal values of transport critical exponents. The lack of universality implies that critical indexes may depend on material properties such as microstructure, composition etc., and that in principle they can be influenced by suitable applied perturbations leading to important informations about the origin of nonuniversality. No firm experimental evidences have been however reported so far, leaving proposed theories of transport nonuniversality practically untested. Here we show that RuO_2-glass compounds have nonuniversal values of transport critical exponents which can be altered by an applied mechanical strain. The controlled variation of the conductance critical index leads to a piezoresistive response which diverges logarithmically at the percolation thresold. Among the proposed theories of nonuniversality, a tunneling-percolation model originally proposed for carbon-black-polymer composites is found to be consistent with the experimental findings, suggesting a common origin of nonuniversality of conducting-insulating compounds for which tunneling is the main mechanism of transport.

Vionnet, Sonia; Grimaldi, Claudio; Maeder, Thomas; Ryser, Peter; Straessler, Sigfrid

2004-03-01

283

Highly tunable spin-dependent electron transport through carbon atomic chains connecting two zigzag graphene nanoribbons  

NASA Astrophysics Data System (ADS)

Motivated by recent experiments of successfully carving out stable carbon atomic chains from graphene, we investigate a device structure of a carbon chain connecting two zigzag graphene nanoribbons with highly tunable spin-dependent transport properties. Our calculation based on the non-equilibrium Green's function approach combined with the density functional theory shows that the transport behavior is sensitive to the spin configuration of the leads and the bridge position in the gap. A bridge in the middle gives an overall good coupling except for around the Fermi energy where the leads with anti-parallel spins create a small transport gap, while the leads with parallel spins give a finite density of states and induce an even-odd oscillation in conductance in terms of the number of atoms in the carbon chain. On the other hand, a bridge at the edge shows a transport behavior associated with the spin-polarized edge states, presenting sharp pure ?-spin and ?-spin peaks beside the Fermi energy in the transmission function. This makes it possible to realize on-chip interconnects or spintronic devices by tuning the spin state of the leads and the bridge position.

Xu, Yuehua; Wang, Bao-Ji; Ke, San-Huang; Yang, Weitao; Alzahrani, A. Z.

2012-09-01

284

Azimuthal anisotropy: Transition from hydrodynamic flow to jet suppression  

SciTech Connect

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.

Lacey, R.; PHENIX Collaboration, et al.

2010-11-09

285

Azimuthal HBT and Transverse Momentum Fluctuations from CERES.  

SciTech Connect

CERES is a dilepton experiment at the CERN SPS, known for its observation of enhanced production of low mass efe- pairs in collisions between heavy nuclei [1]. The upgrade of CERES in 1997-1998 by a radial Time Projection Chamber (TPC) [2] allowed to improve the momentum resolution and the particle identification capability while retaining the cylindrical symmetry. The upgraded experiment is shown in Fig. 1. The upgrade also extended the sensitivity of CERES to hadrons and made possible results like those described below. The measurement of central Pb+Au collisions at the maximum SPS energy of 158 GeV per nucleon in the fall of 2000 was the first run of the fully upgraded CERES and at the same time the last run of this experiment. About 30 million Pb+Au collision events at 158 GeV per nucleon were collected, most of them with centrality within the top 7% of the geometrical cross section {sigma}{sub G} = 6.94 b. Small samples of the 20% and the minimum bias collisions, as well as a short run at 80 AGeV, were recorded in addition. The dilepton mass spectra from this experiment were published in [3]. In this talk I present two particular results of hadron analysis, the azimuthal dependence of two-pion correlations and a differential p{sub t} fluctuation study.

Miskowiec,D.; Rehak, P.; et al.

2007-07-09

286

Characterization of a Mg-dependent, Na-inositol co-transport process in cardiac sarcolemmal vesicles.  

PubMed

[3H]-myo-Inositol transport into cardiac sarcolemmal vesicles is both a time- and Na(+)-dependent process. Transport was stimulated 3-fold by 1 microM valinomycin suggesting the process is electrogenic. myo-Inositol transport was dependent upon the presence of Mn2+ or Mg2+ but not Ca2+. Kinetic analysis revealed a high affinity transport process that was saturable (Vmax, 650 +/- 71 pmoles myo-inositol/mg protein/min; Km, 37.7 +/- 1.3 microM) and a low affinity process that was unsaturable up to 1.0 mM substrate. Transport was not inhibited by 1.0 mM of either L-glucose, D- or L-galactose. However, D-glucose and L-fucose at 1.0 mM were inhibitory. Higher concentrations (30 mM) of each of the sugars inhibited transport. myo-Inositol transport was also inhibited by the inositol isomers (1.0 mM), D-chiro-inositol, epi-inositol and scyllo-inositol with scyllo-inositol being most effective. Kinetic analysis established scyllo-inositol as a competitive inhibitor of cardiac myo-inositol transport, increasing the Km for substrate three-fold (122 +/- 21 microM). These data indicate that inositol transport across cardiac sarcolemma is a Mg(2+)-dependent Na+ co-transport process that is electrogenic and stereospecific. PMID:8411197

Rubin, L J; Hale, C C

1993-06-01

287

Grain-size-dependent thermal transport properties in nanophase yttria-stabilized zirconia.  

SciTech Connect

Understanding the role of grain boundaries in controlling heat flow is critical to the success of many envisioned applications of nanocrystalline materials. This study focuses on the effect of grain boundaries on thermal transport behavior in nanocrystalline yttria-stabilized zirconia (YSZ) coatings prepared by metal-organic chemical vapor deposition. A strong grain-size-dependent reduction in thermal conductivity is observed at all temperatures from 6-480 K. The behavior is due primarily to the effect of interfacial (Kapitza) resistance on thermal transport. In response to the application of heat to a material, interfacial resistance results in a small temperature discontinuity at every grain boundary, an effective that is magnified in nanocrystalline materials because of the large number of grain boundaries. The observed behavior in YSZ is compared with predictions derived from a diffuse-mismatch model. Implications for the possible development of improved thermal barriers based on nano-layered structures with large interfacial thermal resistance are discussed.

Yang, H.-S.; Eastman, J. A.; Thompson, L. J.; Bai, G.-R.

2001-12-13

288

Differential Dependence on Cysteine from Transsulfuration versus Transport During T Cell Activation  

PubMed Central

Abstract The synthesis of glutathione, a major cellular antioxidant with a critical role in T cell proliferation, is limited by cysteine. In this study, we evaluated the contributions of the xC- cystine transporter and the transsulfuration pathway to cysteine provision for glutathione synthesis and antioxidant defense in naïve versus activated T cells and in the immortalized T lymphocyte cell line, Jurkat. We show that the xC- transporter, although absent in naïve T cells, is induced after activation, releasing T cells from their cysteine dependence on antigen-presenting cells. We also demonstrate the existence of an intact transsulfuration pathway in naïve and activated T cells and in Jurkat cells. The flux through the transsulfuration pathway increases in primary but not in transformed T cells in response to oxidative challenge by peroxide. Inhibition of the transsulfuration pathway in both primary and transformed T cells decreases cell viability under oxidative-stress conditions. Antioxid. Redox Signal. 15, 39–47.

Garg, Sanjay K.; Yan, Zhonghua; Vitvitsky, Victor

2011-01-01

289

Alcohol and the calcium-dependent potassium transport of human erythrocytes  

SciTech Connect

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.

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

1985-01-01

290

Fast Water Transport in CNTs: length dependence and entrane/exit effects  

NASA Astrophysics Data System (ADS)

Superfast water transport in carbon nanotube (CNT) membranes has been reported in experimental studies. We use Molecular Dynamics simulations to elucidate the mechanisms of water entry, exit and transport in 2,m-diameter hydrophobic CNTs embedded in a hydrophilic membrane matrix. We demonstrate, for the first time, that under imposed pressures of the order of 1 bar, water entry into the CNT cavity and exit from the CNT end, can occur only on pre-wetted membranes. We conduct large scale simulations for up to 500,m long CNTs and observe a previously unseen dependence of the flow enhancement rates on the CNT length. We relate the present findings to past computational and experimental studies, we discuss previous continuum assessments for this flow and propose underlying physical mechanisms.

Honore Walther, Jens; Koumoutsakos, Petros

2011-11-01

291

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

NASA Astrophysics Data System (ADS)

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.

Talamo, Alberto

2013-05-01

292

Temperature Dependent Transport Study of a Single-Wall Carbon Nanotube Network  

NASA Astrophysics Data System (ADS)

We report the temperature dependence of transport properties of SWCNT network FET devices. The nonlinear ISD-VSD characteristics become linear as increasing temperature because of more diffusive carriers at higher temperature. Zero-bias conductance data is calculated and fitted with simple power-law formula, G~Ta. We obtained two different exponent values of 0.064 and 0.70 from the temperature range from 4.6 K to 40 K, and from 40 K to 295 K respectively. The power-law exponent at high temperature range is consistent with previous studies. However, unusual small power-law exponent at low temperature is attributed to the network junctions, which are disturbing 1D transport in the network structure.

Hwang, Jongseung; Oh, Jung Hyun; Son, Maeng Ho; Ahn, Doyeol; Kim, Hee Tae; Hwang, Sung Woo

2010-01-01

293

Mapping the zinc transporting system in mammary cells: Molecular analysis reveals a phenotype-dependent zinc transporting network during lactation  

PubMed Central

The mammary epithelial cell transitions from a, non-secreting to a terminally differentiated, secreting cell during lactation. Zinc (Zn) is a key modulator of phenotypic transition as it regulates over 300 biological functions including transcription, translation, energy transformation, intracellular signaling and apoptosis. In addition, Zn must be redirected from normal cellular functions into the secretory compartment, as many components of the secretory system are Zn-dependant and an extraordinary amount of Zn is secreted (1–3 mg Zn/d) into milk. Herein, we utilized a “systems biology” approach of genomic and proteomic profiling to explore mechanisms through which Zn is reallocated during phenotype transition in the lactating mammary gland from mice and cultured mammary cells. Nine Zn transporters play key roles in Zn redistribution within the network during lactation. Protein abundance of six Zip (Zip3, Zip5, Zip7, Zip8, Zip10, Zip11) and three ZnT (ZnT2, ZnT4, ZnT9) proteins was expanded > 2-fold during lactation, which was not necessarily reflected by changes in mRNA expression. Our data suggest that Zip5, Zip8 and Zip10 may be key to Zn acquisition from maternal circulation, while multiple Zip proteins reuptake Zn from milk. Confocal microscopy of cultured mammary cells identified the Golgi apparatus (modulated in part by ZnT5, Zip7 and Zip11) and the late endosomal compartment (modulated in part by ZnT2 and Zip3) as key intracellular compartments through which Zn is reallocated during lactation. These results provide an important framework for understanding the Zn transporting network through which mammary gland Zn pools are redistributed and secreted into milk.

Kelleher, Shannon L; Velasquez, Vanessa; Croxford, Thomas P; McCormick, Nicholas H; Lopez, Veronica; MacDavid, Joshua

2011-01-01

294

Oxygen and carbon dioxide transport in time-dependent blood flow past fiber rectangular arrays  

NASA Astrophysics Data System (ADS)

The influence of time-dependent flows on oxygen and carbon dioxide transport for blood flow past fiber arrays arranged in in-line and staggered configurations was computationally investigated as a model for an artificial lung. Both a pulsatile flow, which mimics the flow leaving the right heart and passing through a compliance chamber before entering the artificial lung, and a right ventricular flow, which mimics flow leaving the right heart and directly entering the artificial lung, were considered in addition to a steady flow. The pulsatile flow was modeled as a sinusoidal perturbation superimposed on a steady flow while the right ventricular flow was modeled to accurately depict the period of flow acceleration (increasing flow) and deceleration (decreasing flow) during systole followed by zero flow during diastole. It was observed that the pulsatile flow yielded similar gas transport as compared to the steady flow, while the right ventricular flow resulted in smaller gas transport, with the decrease increasing with Re. The pressure drop across the fiber array (a measure of the resistance), work (an indicator of the work required of the right heart), and shear stress (a measure of potential blood cell activation and damage) are lowest for steady flow, followed by pulsatile flow, and then right ventricular flow. The pressure drop, work, shear stress, and Sherwood numbers (a measure of the gas transport efficiency) decrease with increasing porosity and are smaller for AR<1 as compared to AR>1 (AR is the distance between fibers in the flow direction/distance between fibers in direction perpendicular to flow), although for small porosities the Sherwood numbers are of similar magnitude. In general, for any fiber array geometry, high pressure drop, work, and shear stresses correlate with high Sherwood numbers, and low pressure drop, work, and shear stresses correlate with low Sherwood numbers creating a need for a compromise between pressure drop/work/shear stresses and gas transport.

Zierenberg, Jennifer R.; Fujioka, Hideki; Hirschl, Ronald B.; Bartlett, Robert H.; Grotberg, James B.

2009-03-01

295

P Wave Residuals as a Function of Azimuth, 2. Undulations of the Mantle Low-Velocity Layer as an Explanation  

Microsoft Academic Search

In an earlier paper Bolt and Nuttli presented evidence that the P wave delay times, relative to Berkeley, at a number of seismographic stations in central and northern California, ex!fibit a significant dependence on azimuth of wave approach. Numerical analysis of these data indicates that their amplitudes are too large to be accounted for by crustal structure only. The data

Otto W. Nuttli; Bruce A. Bolt

1969-01-01

296

Study of Azimuthal Correlations in Multiparticle p Tilde p Interactions at 22.4 GeB/C.  

National Technical Information Service (NTIS)

The inclusive azimuthal distributions of pion pairs are studied in anti pp interactions at 24.4 GeV/c. The dependence of the asymmetry parameter on multiplicity, particle rapidity difference, longitudinal and transverse momentum is studied The rho sub 0 a...

B. V. Batyunya I. V. Boguslavsky I. M. Gramenitsky

1979-01-01

297

Functional expression of mammalian glucose transporters in Xenopus laevis oocytes: evidence for cell-dependent insulin sensitivity.  

PubMed Central

We report the functional expression of two different mammalian facilitative glucose transporters in Xenopus oocytes. The RNAs encoding the rat brain and liver glucose transporters were transcribed in vitro and microinjected into Xenopus oocytes. Microinjected cells showed a marked increase in 2-deoxy-D-glucose uptake as compared with controls injected with water. 2-Deoxy-D-glucose uptake increased during the 5 days after microinjection of the RNAs, and the microinjected RNAs were stable for at least 3 days. The expression of functional glucose transporters was dependent on the amount of RNA injected. The oocyte-expressed transporters could be immunoprecipitated with anti-brain and anti-liver glucose transporter-specific antibodies. Uninjected oocytes expressed an endogenous transporter that appeared to be stereospecific and inhibitable by cytochalasin B. This transporter was kinetically and immunologically distinguishable from both rat brain and liver glucose transporters. The uniqueness of this transporter was confirmed by Northern (RNA) blot analysis. The endogenous oocyte transporter was responsive to insulin and to insulinlike growth factor I. Most interestingly, both the rat brain and liver glucose transporters, which were not insulin sensitive in the tissues from which they were cloned, responded to insulin in the oocyte similarly to the endogenous oocyte transporter. These data suggest that the insulin responsiveness of a given glucose transporter depends on the type of cell in which the protein is expressed. The expression of hexose transporters in the microinjected oocytes may help to identify tissue-specific molecules involved in hormonal alterations in hexose transport activity. Images

Vera, J C; Rosen, O M

1989-01-01

298

Experimental evidence for ascorbate-dependent electron transport in leaves with inactive oxygen-evolving complexes.  

PubMed

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 Tyr(Z)(+) 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

Tóth, Szilvia Z; Puthur, Jos T; Nagy, Valéria; Garab, Gyozo

2009-01-14

299

Monte Carlo simulation of time-dependent, transport-limited fluorescent boundary measurements in frequency domain.  

PubMed

Recently, we have presented and experimentally validated a unique numerical solver of the coupled radiative transfer equations (RTEs) for rapidly computing time-dependent excitation and fluorescent light propagation in small animal tomography. Herein, we present a time-dependent Monte Carlo algorithm to validate the forward RTE solver and investigate the impact of physical parameters upon transport-limited measurements in order to best direct the development of the RTE solver for optical tomography. Experimentally, the Monte Carlo simulations for both transport-limited and diffusion-limited propagations are validated using frequency domain photon migration measurements for 1.0%, 0.5%, and 0.2% intralipid solutions containing 1 microM indocyanine green in a 49 cm3 cylindrical phantom corresponding to the small volume employed in small animal tomography. The comparisons between Monte Carlo simulations and the numerical solutions result in mean percent error in amplitude and the phase shift less than 5.0% and 0.7 degrees, respectively, at excitation and emission wavelengths for varying anisotropic factors, lifetimes, and modulation frequencies. Monte Carlo simulations indicate that the accuracy of the forward model is enhanced using (i) suitable source models of photon delivery, (ii) accurate anisotropic factors, and (iii) accurate acceptance angles of collected photons. Monte Carlo simulations also show that the accuracy of the diffusion approximation in the small phantom depends upon (i) the ratio d(phantom)/l(tr), where d(phantom) is the phantom diameter and l(tr) is the transport mean free path; and (ii) the anisotropic factor of the medium. The Monte Carlo simulations validates and guides the future development of an appropriate RTE solver for deployment in small animal optical tomography. PMID:17500461

Pan, Tianshu; Rasmussen, John C; Lee, Jae Hoon; Sevick-Muraca, Eva M

2007-04-01

300

Expression of insulin regulatable glucose transporters in skeletal muscle from Type 2 (non-insulin-dependent) diabetic patients  

Microsoft Academic Search

Summary  A prominent feature of Type 2 (non-insulin-dependent) diabetes mellitus is the inability of insulin to appropiately increase the transport of glucose into target tissue. In adipocytes from individuals with Type 2 diabetes, insulin resistance has been shown to be associated with a depletion of glucose transporters. Similarly, streptozotocin induced diabetes causes a diminished expression of the insulin regulatable glucose transporter

A. Handberg; A. Vaag; P. Damsbo; H. Beck-Nielsen; J. Vinten

1990-01-01

301

Fully predictive time-dependent transport simulations of ITB plasmas in JET, JT-60U and DIII-D  

Microsoft Academic Search

For the first time, the predictive capabilities of the mixed Bohm\\/GyroBohm, Weiland and 'retuned' GLF23 transport models are investigated with ITB discharges from the ITPA ITB database with fully predictive, time-dependent transport simulations. A range of plasma conditions is examined for JET, JT-60U and DIII-D discharges with internal transport barriers (ITBs). The simulations show that the Bohm\\/GyroBohm model is able

T. Tala; F. Imbeaux; V. V. Parail; C. Bourdelle; G. Corrigan; X. Garbet; D. J. Heading; X. Litaudon; P. I. Strand; J. Weiland; JET-EFDA contributors

2006-01-01

302

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

Microsoft Academic Search

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

Francisco Castaneda; Rolf K.-H. Kinne

2005-01-01

303

Humidity dependence of charge transport through DNA revealed by silicon-based nanotweezers manipulation.  

PubMed

The study of the electrical properties of DNA has aroused increasing interest since the last decade. So far, controversial arguments have been put forward to explain the electrical charge transport through DNA. Our experiments on DNA bundles manipulated with silicon-based actuated tweezers demonstrate undoubtedly that humidity is the main factor affecting the electrical conduction in DNA. We explain the quasi-Ohmic behavior of DNA and the exponential dependence of its conductivity with relative humidity from the adsorption of water on the DNA backbone. We propose a quantitative model that is consistent with previous studies on DNA and other materials, like porous silicon, subjected to different humidity conditions. PMID:17827222

Yamahata, Christophe; Collard, Dominique; Takekawa, Tetsuya; Kumemura, Momoko; Hashiguchi, Gen; Fujita, Hiroyuki

2007-09-07

304

Stepwise introduction of model complexity in a generalized master equation approach to time-dependent transport  

NASA Astrophysics Data System (ADS)

We demonstrate that with a stepwise introduction of complexity to a model of an electron system embedded in a photonic cavity and a carefully controlled stepwise truncation of the ensuing many-body space it is possible to describe the time-dependent transport of electrons through the system with a non-Markovian generalized quantum master equation. We show how this approach retains effects of an external magnetic field and the geometry of an anisotropic electronic system. The Coulomb interaction between the electrons and the full electromagnetic coupling between the electrons and the photons are treated in a non-perturbative way using "exact numerical diagonalization".

Gudmundsson, V.; Jonasson, O.; Arnold, Th.; Tang, C.-S.; Goan, H.-S.; Manolescu, A.

2013-02-01

305

Epoxyeicosatrienoic acids affect electrolyte transport in renal tubular epithelial cells: dependence on cyclooxygenase and cell polarity.  

PubMed

We investigated the effects of epoxyeicosatrienoic acids (EETs) on ion transport in the polarized renal distal tubular cell line, Madin-Darby canine kidney (MDCK) C7. Of the four EET regioisomers (5,6-EET, 8,9-EET, 11,12-EET, and 14,15-EET) studied, only apical, but not basolateral, application of 5,6-EET increased short-circuit current (I(sc)) with kinetics similar to those of arachidonic acid. The ion transport was blocked by preincubation with the cyclooxygenase inhibitor indomethacin or with the chloride channel blocker NPPB. Furthermore, both a Cl(-)-free bath solution and the Ca(2+) antagonist verapamil blocked 5,6-EET-induced ion transport. Although the presence of the PGE(2) receptors EP2, EP3, and EP4 was demonstrated, apically added PGE(2) was ineffective and basolaterally added PGE(2) caused a different kinetics in ion transport compared with 5,6-EET. Moreover, PGE(2) synthesis in MDCK C7 cells was unaffected by 5,6-EET treatment. GC/MS/MS analysis of cell supernatants revealed the presence of the biologically inactive 5,6-dihydroxy-PGE(1) in 5,6-EET-treated cells, but not in control cells. Indomethacin suppressed the formation of 5,6-dihydroxy-PGE(1). 5,6-Epoxy-PGE(1), the precursor of 5,6-dihydroxy-PGE(1), caused a similar ion transport as 5,6-EET. Cytochrome P-450 enzymes homolog to human CYP2C8, CYP2C9, and CYP2J2 protein were detected immunologically in the MDCK C7 cells. Our findings suggest that 5,6-EET affects Cl(-) transport in renal distal tubular cells independent of PGE(2) but by a mechanism, dependent on its conversion to 5,6-epoxy-PGE(1) by cyclooxygenase. We suggest a role for this P450 epoxygenase product in the regulation of electrolyte transport, especially as a saluretic compound acting from the luminal side of tubular cells in the mammalian kidney. PMID:17494091

Nüsing, Rolf M; Schweer, Horst; Fleming, Ingrid; Zeldin, Darryl C; Wegmann, Markus

2007-05-09

306

Epoxyeicosatrienoic Acids Affect Electrolyte Transport in Renal Tubular Epithelial Cells: Dependence on Cyclooxygenase and Cell Polarity  

PubMed Central

We investigated the effects of epoxyeicosatrienoic acids (EETs) on ion transport in the polarized renal distal tubular cell line, MDCK C7. Of the four EET regioisomers (5,6-EET, 8,9-EET, 11,12-EET, and 14,15-EET) studied, only apical, but not basolateral, application of 5,6-EET increased short circuit current (Isc) with kinetics similar to those of arachidonic acid. The ion transport was blocked by preincubation with the cyclooxygenase inhibitor indomethacin or with the chloride channel blocker NPPB. Further, both a Cl?-free bath solution and the Ca2+ antagonist verapamil blocked 5,6-EET-induced ion transport. Although the presence of the PGE2 receptors EP2, EP3, and EP4 was demonstrated, apically added PGE2 was ineffective and basolaterally added PGE2 caused a different kinetics in ion transport compared to 5,6-EET. Moreover, PGE2 sythesis in MDCK C7 cells was unaffected by 5,6-EET treatment. GC/MS/MS analysis of cell supernatants revealed the presence of the biologically inactive 5,6-dihydroxy-PGE1 in 5,6-EET-treated cells, but not in control cells. Indomethacin suppressed the formation of 5,6-dihydroxy-PGE1. 5,6-epoxy-PGE1 the precursor of 5,6-dihydroxy-PGE1, caused a similar ion transport as 5,6-EET. Cytochrome P450 enzymes homolog to human CYP2C8, CYP2C9, and CYP2J2 protein were detected immunologically in the MDCK C7 cells. Our findings suggest that 5,6-EET affects Cl-transport in renal distal tubular cells independent of PGE2 but by a mechanism, dependent on its conversion to 5,6-epoxy-PGE1 by cyclooxygenase. We suggest a role for this P450 epoxygenase product in the regulation of electrolyte transport, especially as a saluretic compound acting from the luminal side of tubular cells in the mammalian kidney.

Nusing, Rolf M.; Schweer, Horst; Fleming, Ingrid; Zeldin, Darryl C.; Wegmann, Markus

2007-01-01

307

The hFbpABC Transporter from Haemophilus influenzae Functions as a Binding-Protein-Dependent ABC Transporter with High Specificity and Affinity for Ferric Iron  

PubMed Central

Pathogenic Haemophilus influenzae, Neisseria spp. (Neisseria gonorrhoeae and N. meningitidis), Serratia marcescens, and other gram-negative bacteria utilize a periplasm-to-cytosol FbpABC iron transporter. In this study, we investigated the H. influenzae FbpABC transporter in a siderophore-deficient Escherichia coli background to assess biochemical aspects of FbpABC transporter function. Using a radiolabeled Fe3+ transport assay, we established an apparent Km = 0.9 ?M and Vmax = 1.8 pmol/107cells/min for FbpABC-mediated transport. Complementation experiments showed that hFbpABC is dependent on the FbpA binding protein for transport. The ATPase inhibitor sodium orthovanadate demonstrated dose-dependent inhibition of FbpABC transport, while the protonmotive-force-inhibitor carbonyl cyanide m-chlorophenyl hydrazone had no effect. Metal competition experiments demonstrated that the transporter has high specificity for Fe3+ and selectivity for trivalent metals, including Ga3+ and Al3+, over divalent metals. Metal sensitivity experiments showed that several divalent metals, including copper, nickel, and zinc, exhibited general toxicity towards E. coli. Significantly, gallium-induced toxicity was specific only to E. coli expressing FbpABC. A single-amino-acid mutation in the gene encoding the periplasmic binding protein, FbpA(Y196I), resulted in a greatly diminished iron binding affinity Kd = 5.2 × 10?4 M?1, ?14 orders of magnitude weaker than that of the wild-type protein. Surprisingly, the mutant transporter [FbpA(Y196I)BC] exhibited substantial transport activity, ?35% of wild-type transport, with Km = 1.2 ?M and Vmax = 0.5 pmol/107cells/min. We conclude that the FbpABC complexes possess basic characteristics representative of the family of bacterial binding protein-dependent ABC transporters. However, the specificity and high-affinity binding characteristics suggest that the FbpABC transporters function as specialized transporters satisfying the strict chemical requirements of ferric iron (Fe3+) binding and membrane transport.

Anderson, Damon S.; Adhikari, Pratima; Nowalk, Andrew J.; Chen, Cheng Y.; Mietzner, Timothy A.

2004-01-01

308

The hFbpABC transporter from Haemophilus influenzae functions as a binding-protein-dependent ABC transporter with high specificity and affinity for ferric iron.  

PubMed

Pathogenic Haemophilus influenzae, Neisseria spp. (Neisseria gonorrhoeae and N. meningitidis), Serratia marcescens, and other gram-negative bacteria utilize a periplasm-to-cytosol FbpABC iron transporter. In this study, we investigated the H. influenzae FbpABC transporter in a siderophore-deficient Escherichia coli background to assess biochemical aspects of FbpABC transporter function. Using a radiolabeled Fe3+ transport assay, we established an apparent Km=0.9 microM and Vmax=1.8 pmol/10(7)cells/min for FbpABC-mediated transport. Complementation experiments showed that hFbpABC is dependent on the FbpA binding protein for transport. The ATPase inhibitor sodium orthovanadate demonstrated dose-dependent inhibition of FbpABC transport, while the protonmotive-force-inhibitor carbonyl cyanide m-chlorophenyl hydrazone had no effect. Metal competition experiments demonstrated that the transporter has high specificity for Fe3+ and selectivity for trivalent metals, including Ga3+ and Al3+, over divalent metals. Metal sensitivity experiments showed that several divalent metals, including copper, nickel, and zinc, exhibited general toxicity towards E. coli. Significantly, gallium-induced toxicity was specific only to E. coli expressing FbpABC. A single-amino-acid mutation in the gene encoding the periplasmic binding protein, FbpA(Y196I), resulted in a greatly diminished iron binding affinity Kd=5.2 x 10(-4) M(-1), approximately 14 orders of magnitude weaker than that of the wild-type protein. Surprisingly, the mutant transporter [FbpA(Y196I)BC] exhibited substantial transport activity, approximately 35% of wild-type transport, with Km=1.2 microM and Vmax=0.5 pmol/10(7)cells/min. We conclude that the FbpABC complexes possess basic characteristics representative of the family of bacterial binding protein-dependent ABC transporters. However, the specificity and high-affinity binding characteristics suggest that the FbpABC transporters function as specialized transporters satisfying the strict chemical requirements of ferric iron (Fe3+) binding and membrane transport. PMID:15342592

Anderson, Damon S; Adhikari, Pratima; Nowalk, Andrew J; Chen, Cheng Y; Mietzner, Timothy A

2004-09-01

309

Convective derivatives and Reynolds transport in curvilinear time-dependent coordinates  

NASA Astrophysics Data System (ADS)

A fully covariant formulation of kinematics and dynamics of fluid flows and heat transfer is developed in time-dependent curvilinear coordinate systems. These moving and deformable reference frames have the same properties of a fluid motion and they can be successfully applied to a variety of problems ranging from numerical analysis to theoretical physics. The classical Reynolds transport theorem, the Euler formula and the acceleration addition theorem are extended to these general types of coordinates through a generalization of the convected differentiation concept originally introduced by Oldroyd (1950 Proc. R. Soc. A 200 523-41). A rigorous formulation of dynamical equations and conservation laws in curvilinear time-dependent coordinates could be the key for the construction of variational principles based on the method of constrained variations.

Venturi, Daniele

2009-03-01

310

Time-dependent versus static quantum transport simulations beyond linear response  

NASA Astrophysics Data System (ADS)

To explore whether the density-functional theory-nonequilibrium Green’s function formalism (DFT-NEGF) provides a rigorous framework for quantum transport, we carried out time-dependent density-functional-theory (TDDFT) calculations of the transient current through two realistic molecular devices, a carbon chain and a benzenediol molecule between two aluminum electrodes. The TDDFT simulations for the steady-state current exactly reproduce the results of fully self-consistent DFT-NEGF calculations even beyond linear response. In contrast, sizable differences are found with respect to an equilibrium, non-self-consistent treatment, which are related here to differences in the Kohn-Sham and fully interacting susceptibilities of the device region. Moreover, earlier analytical conjectures on the equivalence of static and time-dependent approaches in the low-bias regime are confirmed with high numerical precision.

Yam, Chiyung; Zheng, Xiao; Chen, Guanhua; Wang, Yong; Frauenheim, Thomas; Niehaus, Thomas A.

2011-06-01

311

Spin-Dependent Electron Transport in an Armchair Graphene Nanoribbon Subject to Charge and Spin Biases  

NASA Astrophysics Data System (ADS)

We study the spin-dependent electron transport in an armchair graphene nanoribbon sample driven by both the charge and the spin biases within the tight-binding framework. By numerical calculations we give the spin-dependent currents for a fixed spin bias as a function of the charge bias. It is found that we can let only one type of spin current pass through the graphene nanoribbon for a wide range of charge bias, which is due to the difference of the bias voltage windows for different spin electrons when the charge and the spin biases coexist. Moreover, the pure spin current can be controlled via the charge bias. Our results are suggestive for developing new kinds of spin filters.

Zhang, Xiao-Wei; Zhao, Hua; Sang, Tian; Liu, Xiao-Chun; Cai, Tuo

2013-01-01

312

Charge transport in DNA: dependence of diffusion coefficient on temperature and electron-phonon coupling constant.  

PubMed

The diffusion coefficient is calculated for a charge propagating along a double-stranded DNA, while it interacts with the nonlinear fluctuational openings of base pairs. The latter structural dynamics of DNA is described by the Peyrard-Bishop-Dauxois model [T. Dauxois, M. Peyrard, and A. R. Bishop, Phys Rev. E 47 R44 (1993)], which represents essential anharmonicities of base-pair stretchings. The dependence of the diffusion coefficient on the temperature and the electron-phonon coupling constant is presented. The diffusion coefficient decreases when either the temperature or the electron-phonon coupling increases. Analytical expressions are provided that describe the temperature dependence of the diffusion coefficient. The variation of the parameters of these expressions with the electron-phonon coupling constant is also discussed. These results quantitatively demonstrate how DNA structural nonlinear dynamics affects macroscopic charge transport properties. PMID:22181442

Kalosakas, G

2011-11-10

313

Field dependent transport properties in InAs nanowire field effect transistors.  

PubMed

We present detailed studies of the field dependent transport properties of InAs nanowire field-effect transistors. Transconductance dependence on both vertical and lateral fields is discussed. Velocity-field plots are constructed from a large set of output and transfer curves that show negative differential conductance behavior and marked mobility degradation at high injection fields. Two dimensional electrothermal simulations at current densities similar to those measured in the InAs NWFET devices indicate that a significant temperature rise occurs in the channel due to enhanced phonon scattering that leads to the observed mobility degradation. Scanning transmission electron microscopy measurements on devices operated at high current densities reveal arsenic vaporization and crystal deformation in the subject nanowires. PMID:18783282

Dayeh, Shadi A; Susac, Darija; Kavanagh, Karen L; Yu, Edward T; Wang, Deli

2008-09-11

314

Riemann solvers for time-dependent transport based on the maximum entropy and spherical harmonics closures  

NASA Astrophysics Data System (ADS)

A Roe-type Riemann solver is used to solve the spherical harmonics and maximum entropy approximations to the time-dependent neutron transport equation. The maximum entropy closure for the two-moment approximation of the transport equation is presented. It is based on the use of the most likely form of the distribution, restricted by certain constraints, to close the equations. It is designed to have a wider range of applicability than a linear two-moment closure. The spherical harmonics expansion of the transport equation is also reviewed. The high-resolution interpolation scheme of standard Riemann solvers has been modified to work with these closures. Three boundary conditions for use with the Riemann solver and the two closures have been developed and are described. They essentially provide the Mark and Marshak boundary conditions, and an extension of the Marshak boundary conditions. The maximum entropy closure does well in deep penetration problems but has difficulties if there is more than one special direction in the problem. For a pulsed isotropic line source the spherical harmonics produce a negative scalar flux at very early times. For less severe problems, or after a few collision times, even low-order spherical harmonics approximations yield excellent results. The Riemann solver provides an exceptionally robust method for numerically solving the resulting equations.

Brunner, Thomas Andrew

315

Vitreal Pharmacokinetics of Biotinylated Ganciclovir: Role of Sodium-Dependent Multivitamin Transporter Expressed on Retina  

PubMed Central

Abstract Purpose The objective of this study was to investigate the role of sodium-dependent multiple vitamin transporter (SMVT) on Biotin-Ganciclovir (biotin-GCV) uptake on both human retinal pigmented epithelium cell line (ARPE-19) and rabbit retina. Study also aims to delineate the vitreal pharmacokinetics of biotin-GCV. Method ARPE-19 was employed to study the in vitro uptake experiments. New Zealand white albino rabbits were used to study in vivo retinal uptake and vitreal pharmacokinetics following intravitreal administration of biotin-GCV. In vitro uptake kinetics of [3H] biotin was determined at various initial concentrations. Competitive inhibition studies were conducted in the presence of unlabelled biotin, desthiobiotin, pantothenic acid, and lipoic acid. Various other uptake studies were performed to functionally characterize the transporter. To provide the molecular evidence of this transporter, Reverse Transcription-Polymerase Chain Reaction (RT-PCR) studies were also conducted. In vivo retinal/choroidal uptake studies were carried out with New Zealand albino rabbits. Unconscious animal ocular microdialysis studies were performed in order to evaluate intravitreal pharmacokinetics of GCV and Biotin-GCV. Results Uptake of [3H] biotin into ARPE-19 was linear over 7min, and found to be saturable with Km of 138.25 ?M and Vmax of 38.85 pmol/min/mg protein. Both pantothenic acid and lipoic acid decreased significantly in uptake of biotin in the concentration-dependent manner. Uptake of biotin into ARPE-19 was found to be temperature, energy, and Na+ dependent but Cl? independent. Further, RT-PCR studies identified a band exhibiting presence of hSMVT on ARPE-19. Biotin-GCV is recognized by SMVT system present on the ARPE-19 and rabbit retina. Vitreal Pharmacokinetics profile reveals that most of the parameters were not significantly different for GCV and Biotin-GCV. However, use of Biotin-GCV may result in sustain levels of regenerated GCV in vitreous. Conclusions SMVT was identified and functionally characterized on ARPE-19 cells. Further, Biotin-GCV shares this transport system. Vitreal pharmacokinetics of the conjugate was determined in unconscious rabbit model.

Janoria, Kumar G.; Boddu, Sai H.S.; Wang, Zhiying; Paturi, Durga K.; Samanta, Swapan; Pal, Dhananjay

2009-01-01

316

Yeast Mn2+ transporter, Smf1p, is regulated by ubiquitin-dependent vacuolar protein sorting.  

PubMed Central

Conditional cdc1(Ts) mutants of S. cerevisiae arrest with a phenotype similar to that exhibited by Mn(2+)-depleted cells. Sequence similarity between Cdc1p and a class of Mn(2+)-dependent phosphoesterases, as well as the observation that conditional cdc1(Ts) growth can be ameliorated by Mn(2+) supplement, suggests that Cdc1p activity is sensitive to intracellular Mn(2+) levels. This article identifies several previously uncharacterized cdc1(Ts) suppressors as class E vps (vacuolar protein sorting) mutants and shows that these, as well as other vps mutants, accumulate high levels of intracellular Mn(2+). Yeast VPS genes play a role in delivery of membrane transporters to the vacuole for degradation, and we show that the vps mutants accumulate elevated levels of the high-affinity Mn(2+) transporter Smf1p. cdc1(Ts) conditional growth is also alleviated by mutations, including doa4 and ubc4, that compromise protein ubiquitination, and these ubiquitination defects are associated with Smf1p accumulation. Epistasis studies show that these suppressors require functional Smf1p to alleviate the cdc1(Ts) growth defect, whereas Smf1p is dispensable for cdc1(Ts) suppression by a mutation (cos16/per1) that does not influence intracellular Mn(2+) levels. Because Smf1p is ubiquitinated in vivo, we propose that Smf1p is targeted to the vacuole for degradation by ubiquitination-dependent protein sorting.

Eguez, Lorena; Chung, Young-Sook; Kuchibhatla, Ajay; Paidhungat, Madan; Garrett, Stephen

2004-01-01

317

Spin-dependent electron transport in a Rashba quantum wire with rough edges  

NASA Astrophysics Data System (ADS)

We investigate theoretically the spin-dependent electron transport in a Rashba quantum wire with rough edges. The charge and spin conductances are calculated as function of the electron energy and wire length by adopting the spin-resolved lattice Green function method. For a single disordered Rashba wire, it is found that the charge conductance quantization is destroyed by the edge disorder. However, a nonzero spin conductance can be generated and its amplitude can be manipulated by varying the wire length, which is attributed to the broken structure symmetries and the spin-dependent quantum interference induced by the rough boundaries. For a large ensemble of disordered Rashba wires, the average charge conductance decreases monotonically, however, the average spin conductance increases to a maximum value and then decreases, with increasing wire length. Further study shows that the influence of the rough edges on the charge and spin conductances can be eliminated by applying a perpendicular magnetic field to the wire. In addition, a very large magnitude of the spin conductance can be achieved when the electron energy lies between the two thresholds of each pair of subbands. These findings may not only benefit to further apprehend the transport properties of the Rashba low-dimensional systems but also provide some theoretical instructions to the application of spintronics devices.

Xiao, X. B.; Li, H. L.; Zhou, G. H.; Liu, N. H.

2012-09-01

318

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

PubMed

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. PMID:21415476

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

2011-03-17

319

Sodium dependency of active chloride transport across isolated fish skin (Gillichthys mirabilis).  

PubMed

1. The effects of thiocyanate, ouabain, ion-substituted Ringer solution and electrochemical gradients on Na+ and Cl- transport were examined using the isolated skin of the marine teleost, Gillichthys mirabilis. 2. Bilateral replacement of Na+ with choline in the bathing solutions reduces net Cl- flux by 93%, indicating that active Cl- transport by the skin is Na-dependent. 3. Thiocyanate inhibits short-circuit current with an ED50 of 6.4 x 10(-4)M, and, at 10(-2)M, decreases Cl-efflux, influx, net flux and short-circuit current by 68, 33, 74 and 81%, respectively. 4. Ouabain (10(-5)M) reduces Cl- efflux and net flux by 56 and 86%, respectively, indicating that the Cl- transport requires Na,K-ATPase. 5. Subsequent addition of thiocyanate to ouabain-treated skin reduces Cl- efflux, net flux and short-circuit current, suggesting that the two agents operate at different sites involved in Cl- transport. 6. Unilateral substitution of gluconate for Cl- on the serosal side does not affect Cl- influx, indicating that Cl- passive transport is via Fickean diffusion, not Cl-Cl exchange diffusion. 7. The addition of NaCl to the mucosal side, which mimics the in vivo sea-water condition, increases Cl- influx and transepithelial potential and decreases tissue resistance. The net flux (secretion) of Cl- with hypertonic saline on the mucosal side (0.51 +/- 0.06 muequiv/cm2 . hr) demonstrates that the skin could secrete Cl- in vivo. 8. Na+ fluxes across the skin are passive, as the observed flux ration (efflux/influx) is similar to that predicted by the Ussing-Teorell equation under both closed- and open-circuit conditions. 9. The permeability ratio (PNa:PCl) in approximately 5.4:1.0, indicating that the skin is more permeable to Na+, and that at least part of the serosa-positive transepithelial potential may be a Na+ diffusion potential. 10. The results suggest that Cl- secretion by Gillichthys skin is secondary active transport involving Na,K-ATPase and serosal Na+. PMID:7320911

Marshall, W S

1981-01-01

320

Sodium dependency of active chloride transport across isolated fish skin (Gillichthys mirabilis).  

PubMed Central

1. The effects of thiocyanate, ouabain, ion-substituted Ringer solution and electrochemical gradients on Na+ and Cl- transport were examined using the isolated skin of the marine teleost, Gillichthys mirabilis. 2. Bilateral replacement of Na+ with choline in the bathing solutions reduces net Cl- flux by 93%, indicating that active Cl- transport by the skin is Na-dependent. 3. Thiocyanate inhibits short-circuit current with an ED50 of 6.4 x 10(-4)M, and, at 10(-2)M, decreases Cl-efflux, influx, net flux and short-circuit current by 68, 33, 74 and 81%, respectively. 4. Ouabain (10(-5)M) reduces Cl- efflux and net flux by 56 and 86%, respectively, indicating that the Cl- transport requires Na,K-ATPase. 5. Subsequent addition of thiocyanate to ouabain-treated skin reduces Cl- efflux, net flux and short-circuit current, suggesting that the two agents operate at different sites involved in Cl- transport. 6. Unilateral substitution of gluconate for Cl- on the serosal side does not affect Cl- influx, indicating that Cl- passive transport is via Fickean diffusion, not Cl-Cl exchange diffusion. 7. The addition of NaCl to the mucosal side, which mimics the in vivo sea-water condition, increases Cl- influx and transepithelial potential and decreases tissue resistance. The net flux (secretion) of Cl- with hypertonic saline on the mucosal side (0.51 +/- 0.06 muequiv/cm2 . hr) demonstrates that the skin could secrete Cl- in vivo. 8. Na+ fluxes across the skin are passive, as the observed flux ration (efflux/influx) is similar to that predicted by the Ussing-Teorell equation under both closed- and open-circuit conditions. 9. The permeability ratio (PNa:PCl) in approximately 5.4:1.0, indicating that the skin is more permeable to Na+, and that at least part of the serosa-positive transepithelial potential may be a Na+ diffusion potential. 10. The results suggest that Cl- secretion by Gillichthys skin is secondary active transport involving Na,K-ATPase and serosal Na+.

Marshall, W S

1981-01-01

321

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

SciTech Connect

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.

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

322

Dopamine and norepinephrine transporter-dependent c-Fos production in vitro: relevance to neuroadaptation.  

PubMed

Cocaine, methylphenidate and other drugs that block dopamine transport indirectly promote immediate early gene expression, via dopamine-mediated activation of D1 dopamine receptors. Increased expression of the immediate early gene (IEG) c-fos, initiates a cascade of intracellular events that may underlie neuroadaptive changes following repeated exposure to the drugs. We investigated whether substrates (dopamine, norepinephrine) of the human dopamine (hDAT) and norepinephrine (hNET) transporters can directly induce c-Fos protein in HEK-293 (HEK) cells transfected with the hDAT and hNET and whether PKC modulators affect this process. Dopamine and norepinephrine robustly induced c-Fos immunofluorescence in both hDAT and hNET cells, but not in untransfected HEK-293 cells, demonstrating that catecholamine-induced c-Fos induction was DAT- and NET-dependent. The PKC activator PMA induced c-Fos in hDAT, hNET and HEK cell lines indicating that PKC stimulated c-Fos independent of transporters. The PKC inhibitor bisindolylmaleimide I (BIS) significantly increased c-Fos expression in hDAT cells, but not in hNET or HEK-293 cells, suggesting that inhibition of DAT-mediated phosphorylation results in c-Fos induction. BIS pretreatment abolished norepinephrine-induced c-Fos expression hNET but not dopamine-induced c-Fos induction in hDAT cells. In conclusion, induction of c-Fos by dopamine and norepinephrine requires the presence of hDAT and hNET but the contributions of hDAT and hNET to c-Fos induction is distinguishable on the basis of differing responses to a PKC inhibitor. These findings present a cell system and methodology for investigating the potential contribution of monoamine transporters to pre-synaptic neuroadaptation. PMID:15763138

Yatin, Servet M; Miller, Gregory M; Madras, Bertha K

2005-04-15

323

3-D prestack migration of common-azimuth data  

SciTech Connect

In principle, downward continuation of 3-D prestack data should be carried out in the 5-D space of full 3-D prestack geometry (recording time, source surface location, and receiver surface location), even when the data sets to be migrated have fewer dimensions, as in the case of common-azimuth data sets that are only four dimensional. This increase in dimensionality of the computational space causes a severe increase in the amount of computations required for migrating the data. Unless this computational efficiency issue is solved, 3-D prestack migration methods based on downward continuation cannot compete with Kirchhoff methods. The authors address this problem by presenting a method for downward continuing common-azimuth data in the original 4-D space of the common-azimuth data geometry. The method is based on a new common-azimuth downward-continuation operator derived by a stationary-phase approximation of the full 3-D prestack downward-continuation operator expressed in the frequency-wavenumber domain. Although the new common-azimuth operator is exact only for constant velocity, a ray-theoretical interpretation of the stationary-phase approximation enables one to derive an accurate generalization of the method to media with both vertical and lateral velocity variations. The proposed migration method successfully imaged a synthetic data set that was generated assuming strong lateral and vertical velocity gradients.

Biondi, B.; Palacharla, G. [Stanford Exploration Project, CA (United States)

1996-11-01

324

Unusual Temperature and Field Dependence of Transport Properties Ba(Fe1-xCox)2As2  

NASA Astrophysics Data System (ADS)

The in-plane transport properties of Ba(Fe1-xCox)2As2 single crystals with x = 0.02 ˜ 0.28 was measured as a function of temperature (2 ˜ 300 K) and magnetic field (up to 14 Tesla). A Cobalt doping composition-temperature (x-T) phase diagram was plotted and shows a non-Fermi liquid (NFL) transport behavior around the optimal doing level. The Hall effect and magneto-resistance results also show an anomaly and a change of field dependence around the optimal doing. The underlying physics of such unusual temperature and field dependence of transport properties ab plane will be discussed.

Xiong, Yimin; Li, Jianneng; Jin, Rongying

2010-10-01

325

Sex-Dependent Modulation of Ethanol Consumption in Vesicular Monoamine Transporter 2 (VMAT2) and Dopamine Transporter (DAT) Knockout Mice  

Microsoft Academic Search

Several lines of evidence suggest that monoaminergic systems, especially dopaminergic and serotoninergic systems, modulate ethanol consumption. Humans display significant differences in expression of the vesicular and plasma membrane monoamine transporters important for monoaminergic functions, including the vesicular monoamine transporter (VMAT2, SLC18A2) and dopamine transporter (DAT, SLC6A3). In addition, many ethanol effects differ by sex in both humans and animal models.

F Scott Hall; I Sora; G R Uhl

2003-01-01

326

Time-dependent transport in heterogeneous formations of bimodal structures: 2. Results  

NASA Astrophysics Data System (ADS)

The theoretical results of part 1 [Dagan and Fiori, 2003] for modeling time-dependent, advective transport of a conservative solute in porous formations of bimodal structure are applied to illustrate the behavior of a few trajectory statistical moments as function of time, of the permeability contrast ?, and of the inclusions volume density n. The computations are carried out for circular (2D) and spherical (3D) inclusions to represent isotropic media. Advective transport is solved by studying the distortion of a thin plume, linear (2D) or planar (3D), normal to the mean velocity U and moving through a single inclusion. The deformation of the plume is determined from the residual trajectories of solute particles that are derived numerically by a quadrature. The longitudinal macrodispersivity is defined by ?L(t; n, ?) = (2U)-1dX11/dt, where X11 is the trajectories second moment in the mean flow direction. The general behavior of the time-dependent longitudinal dispersivity ?L(t; n, ?) and, in particular, its constant, large time limit are examined. The tendency of ?L to the "Fickian" limit with time depends strongly on the conductivity contrast; in particular, for low permeable inclusions (? ? 1) it may be extremely slow. It is shown that the first-order approximation in the conductivity contrast ? is of limited validity (0.3 < ? < 2). The transverse moment X22 tends asymptotically to a constant value. The analysis of the trajectory high order moments shows that the probability density function (pdf) of the solute trajectories tends to normality at large time. Similar to the "Fickian" limit the normal distribution may be reached at very large time in presence of low conductivity inclusions, with the pdf characterized by significant tailing for the trailing part of the pdf.

Fiori, A.; Dagan, G.

2003-05-01

327

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

SciTech Connect

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

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

2012-11-28

328

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

SciTech Connect

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.

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

2012-11-27

329

Sodium-dependent glucose transporter protein as a potential therapeutic target for improving glycemic control in diabetes.  

PubMed

Glucose is transported across the cell membrane by two different types of glucose transporters: glucose-facilitated transporters and sodium-dependent glucose transport (SGLT) proteins. Regulation of SGLT activity (namely, inhibition of SGLT1 and SGLT2 activity and stimulation of SGLT3 activity) represents a potential means of managing hyperglycemia and diabetes, thus preventing complications of diabetes. The purpose of the present review is to discuss the role of SGLT proteins in the pathophysiology of diabetes and to describe the mechanisms by which these transporters may be used for glycemic control and the treatment of diabetes. The regulatory processes involved in SGLT-mediated glucose uptake are also described briefly. This information provides new insight into the complementary mechanisms involved in the regulation of SGLT-mediated glucose transport as well as a basis for further investigation. PMID:22133196

Castaneda-Sceppa, Carmen; Castaneda, Francisco

2011-12-01

330

Functional characterisation of human SGLT-5 as a novel kidney-specific sodium-dependent sugar transporter.  

PubMed

Sodium glucose cotransporters (SGLT) actively catalyse carbohydrate transport across cellular membranes. Six of the 12 known SGLT family members have the capacity to bind and/or transport monosaccharides (SGLT-1 to 6); of these, all but SGLT-5 have been characterised. Here we demonstrate that human SGLT-5 is exclusively expressed in the kidney. Four splice variants were detected and the most abundant SGLT-5-mRNA was functionally characterised. SGLT-5 mediates sodium-dependent [(14)C]-?-methyl-D-glucose (AMG) transport that can be inhibited by mannose, fructose, glucose, and galactose. Uptake studies using demonstrated high capacity transport for mannose and fructose and, to a lesser extent, glucose, AMG, and galactose. SGLT-5 mediated mannose, fructose and AMG transport was weakly (?M potency) inhibited by SGLT-2 inhibitors. In summary, we have characterised SGLT-5 as a kidney mannose transporter. Further studies are warranted to explore the physiological role of SGLT-5. PMID:22212718

Grempler, Rolf; Augustin, Robert; Froehner, Stefanie; Hildebrandt, Tobias; Simon, Eric; Mark, Michael; Eickelmann, Peter

2011-12-30

331

Direction dependent prices in public transport: A good idea? The back haul pricing problem for a monopolistic public transport firm  

Microsoft Academic Search

Markets for transport are often characterised by unequal demand in both directions: every morning during peak hours the trains are crowded while moving towards the direction of large cities, whereas they may be almost empty in the other direction. In this paper we discuss the implications of these imbalances for price setting of transport firms. From the viewpoint of economic

Piet Rietveld; Roberto Roson

2002-01-01

332

Structural phase-dependent hole localization and transport in bismuth vanadate  

NASA Astrophysics Data System (ADS)

We present theoretical evidence for the phase dependence of hole localization and transport in bismuth vanadate (BiVO4). Our hybrid density-functional theory calculations predict that, in the tetragonal phase [tetragonal scheelite BiVO4 (ts-BiVO4)], an excess hole tends to localize around a BiO8 polyhedron with strong lattice distortion, whereas, in the monoclinic phase [monoclinic scheelite BiVO4 (ms-BiVO4)], it spreads over many lattice sites. The phase-dependent behavior is likely related to the higher structural stability of ms-BiVO4 than ts-BiVO4, which may suppress hole-induced lattice distortions. Our study also demonstrates that the relatively weakly localized hole in ms-BiVO4 undergoes faster diffusion compared to the case of ts-BiVO4, irrespective of the fact that the degrees of localization and mobility vary depending on the choice of exchange-correlation functional. The mobility difference may provide an explanation for the enhanced photocatalytic activity of ms-BiVO4 over ts-BiVO4 for water oxidation, considering that the increased mobility would lead to an increase in the hole current to the catalyst surface.

Kweon, Kyoung E.; Hwang, Gyeong S.

2013-05-01

333

The Amino Terminus of Tau Inhibits Kinesin-Dependent Axonal Transport: Implications for Filament Toxicity  

PubMed Central

The neuropathology of Alzheimer's disease (AD) and other tauopathies is characterized by filamentous deposits of the microtubule-associated protein tau, but the relationship between tau polymerization and neurotoxicity is unknown. Here, we examined effects of filamentous tau on fast axonal transport (FAT) using isolated squid axoplasm. Monomeric and filamentous forms of recombinant human tau were perfused in axoplasm, and their effects on kinesin- and dynein-dependent FAT rates were evaluated by video microscopy. Although perfusion of monomeric tau at physiological concentrations showed no effect, tau filaments at the same concentrations selectively inhibited antero-grade (kinesin-dependent) FAT, triggering the release of conventional kinesin from axoplasmic vesicles. Pharmacological experiments indicated that the effect of tau filaments on FAT is mediated by protein phosphatase 1 (PP1) and glycogen synthase kinase-3 (GSK-3) activities. Moreover, deletion analysis suggested that these effects depend on a conserved 18-amino-acid sequence at the amino terminus of tau. Interestingly, monomeric tau isoforms lacking the C-terminal half of the molecule (including the microtubule binding region) recapitulated the effects of full-length filamentous tau. Our results suggest that pathological tau aggregation contributes to neurodegeneration by altering a regulatory pathway for FAT.

LaPointe, Nichole E.; Morfini, Gerardo; Pigino, Gustavo; Gaisina, Irina N.; Kozikowski, Alan P.; Binder, Lester I.; Brady, Scott T.

2009-01-01

334

Pressure dependence of the large polaron transport in anatase TiO2 single crystals  

NASA Astrophysics Data System (ADS)

Anatase is a TiO2 polymorph which is a 3.2 eV gap semiconductor interesting for several applications, including catalysis, photocatalysis, and, especially, dye-sensitized solar cells. Surprisingly, transparent single crystals of anatase grown in our laboratory show a metallic resistivity above 60 K which origin is a shallow donor level created by oxygen vacancies. The high value of the resistivity and its T^3 temperature dependence are the result of the polaronic nature of the charge carriers which is supported by the Seebeck coefficient (S). The application of hydrostatic pressure fails to close the donor level and to extend the conducting state to the entire temperature range. Instead, we have found a non-monotonic variation of the low temperature activation energy with applied pressure which is ascribed to the change of polaron's mobility. Thermo-electric power exhibits an unconventional temperature and pressure dependence shedding an additional light on the conductivity mechanism in this compound. The pressure dependence of S is governed by the transport of the large entropy associated with the polaron formation.

Ja?imovi?, Ja?im; Vaju, Cristian; Berger, Helmuth; Magrez, Arnaud; Cerovski, Viktor; Žiki?, Radomir; Gaál, Richard; Forró, László

2012-02-01

335

Concentrative uridine transport by murine splenocytes: kinetics, substrate specificity, and sodium dependency.  

PubMed

A previous report from this laboratory indicated that the concentration of free uridine (Urd) in many normal murine tissues greatly exceeds that in plasma. We now report that Urd uptake by isolated murine splenocytes is concentrative, and that the rate of uptake from medium containing 10 to 500 microM [3H]Urd conforms to a process that is saturable with a Km of 38.0 +/- 4.1 (SE) microM and Vmax of 2.70 +/- 0.27 pmol/s/microliter cell water. Other ribosyl and deoxyribosyl pyrimidine nucleosides or their analogues were not concentrated by splenocytes; however, ribosyl and deoxyribosyl purine nucleosides and, to a lesser extent, deoxyuridine did inhibit Urd uptake. In this system Urd uptake was not inhibited by 1 microM nitrobenzylthioinosine or 10 microM dipyridamole but was significantly inhibited by 5 mM NaN3 or 250 microM KCN. Transport of Urd involves Na+ cotransport as evidenced by complete inhibition when Na+ is replaced by Li+ in the incubation medium, and it is also inhibited by 3 mM ouabain. Active Urd transport coexists with the nonspecific, carrier mediated, facilitated diffusion of nucleosides as demonstrated by the inhibition of Urd efflux and thymidine influx in splenocytes by nitrobenzylthioinosine and dipyridamole. Under identical conditions, Urd entry into L1210 leukemia cells was nonconcentrative and non-Na+ dependent but inhibited by nitrobenzylthionosine. That nucleosides enter most cultured neoplastic cell lines by facilitated diffusion and not the active transport mechanism for Urd confirms earlier findings and may represent an exploitable target for chemotherapy. PMID:3567894

Darnowski, J W; Holdridge, C; Handschumacher, R E

1987-05-15

336

Stoichiometry dependent electron transport and gas sensing properties of indium oxide nanowires  

NASA Astrophysics Data System (ADS)

The effect of stoichiometry of single crystalline In2O3 nanowires on electrical transport and gas sensing was investigated. The nanowires were synthesized by vapor phase transport and had diameters ranging from 80 to 100 nm and lengths between 10 and 20 ?m, with a growth direction of [001]. Transport measurements revealed n-type conduction, attributed to the presence of oxygen vacancies in the crystal lattice. As-grown In2O3 nanowires were shown to have a carrier concentration of ?5 × 1017 cm-3, while nanowires that were annealed in wet O2 showed a reduced carrier concentration of less than 1016 cm-3. Temperature dependent conductivity measurements on the as-grown nanowires and analysis of the thermally activated Arrhenius conduction for the temperature range of 77-350 K yielded an activation energy of 0.12 eV. This is explained on the basis of carrier exchange that occurs between the surface states and the bulk of the nanowire, resulting in a depleted surface layer of thickness of the order of the Debye length (LD), estimated to be about 3-4 nm for the as-grown nanowires and about 10 times higher for the more stoichiometric nanowires. Significant changes in the electrical conductance of individual In2O3 nanowires were also observed within several seconds of exposure to NH3 and O2 gas molecules at room temperature, thus demonstrating the potential use of In2O3 nanowires as efficient miniaturized chemical sensors. The sensing mechanism is dominated by the nanowire channel conductance, and a simple energy band diagram is used to explain the change in conductivity when gas molecules adsorbed on the nanowire surface influence its electrical properties. Less stoichiometric nanowires were found to be more sensitive to oxidizing gases while more stoichiometric nanowires showed significantly enhanced response to reducing gases.

Gali, Pradeep; Sapkota, Gopal; Syllaios, A. J.; Littler, Chris; Philipose, U.

2013-06-01

337

Temperature-dependent solid-state electron transport through bacteriorhodopsin: experimental evidence for multiple transport paths through proteins.  

PubMed

Electron transport (ETp) across bacteriorhodopsin (bR), a natural proton pump protein, in the solid state (dry) monolayer configuration, was studied as a function of temperature. Transport changes from thermally activated at T > 200 K to temperature independent at <130 K, similar to what we have observed earlier for BSA and apo-azurin. The relatively large activation energy and high temperature stability leads to conditions where bR transports remarkably high current densities above room temperature. Severing the chemical bond between the protein and the retinal polyene only slightly affected the main electron transport via bR. Another thermally activated transport path opens upon retinal oxime production, instead of or in addition to the natural retinal. Transport through either or both of these paths occurs on a background of a general temperature-independent transport. These results lead us to propose a generalized mechanism for ETp across proteins, in which tunneling and hopping coexist and dominate in different temperature regimes. PMID:22296717

Sepunaru, Lior; Friedman, Noga; Pecht, Israel; Sheves, Mordechai; Cahen, David

2012-02-27

338

Isolation and characterization of a sodium-dependent phosphate transporter gene in Dunaliella viridis.  

PubMed

A sodium-dependent phosphate transporter gene, DvSPT1, was isolated from a cDNA library using a probe derived from a subtracted cDNA library of Dunaliella viridis. Sequencing analyses revealed a cDNA sequence of 2649 bp long and encoded an open-reading frame consisting of 672 amino acids. The deduced amino acid sequence of DvSPT1 exhibited 31.2% identity to that of TcPHO from Tetraselmis chui. Hydrophobicity and secondary structure prediction revealed 11 conserved transmembrane domains similar to those found in PHO89 from Saccharomyces cerevisiae and PHO4 from Neurospora crassa. Northern blot analysis indicated that the DvSPT1 expression was induced upon NaCl hyperosmotic stress or phosphate depletion. Functional characterization in yeast Na+ export pump mutant G19 suggested that DvSPT1 encoded a Na+ transporter protein. The gene sequence of GDvSPT1 (7922 bp) was isolated from a genomic library of D. viridis. Southern blot analysis indicated that there exist at least two homologous genes in D. viridis. PMID:16359638

Li, Qiyun; Gao, Xiaoshu; Sun, Yu; Zhang, Qingqi; Song, Rentao; Xu, Zhengkai

2005-12-07

339

Spin-dependent Transport in GaAs/MnAs Core/shell Nanowires  

NASA Astrophysics Data System (ADS)

The integration of a metallic ferromagnet (FM) with a semiconductor (S) in axially- and radially modulated nanowires (NWs) has the potential to open up new opportunities in nanospintronics. We describe a comprehensive study of the structure, magnetism and electrical transport in hybrid core/shell S(GaAs)/FM(MnAs) NWs synthesized by molecular beam epitaxy. This is an unusual system where the competition between magnetocrystalline and shape anisotropies in the FM shell creates a magnetic ordering regime which is distinct from conventional FM metal NWs. We report four probe measurements of the temperature dependence of conductivity and the magnetoresistance (MR) in single NWs over a temperature range 0.5 K - 300 K and in magnetic fields ranging up to 80 kOe. Assuming that electrical transport is dominated by the metallic shell, we use the measured anisotropic MR in conjunction with micromagnetic simulations to gain insight into the magnetization reversal process of the FM shell. We also discuss the possible origins of a striking negative linear MR at high field which becomes more pronounced with increasing temperature. Supported by NSF-MRSEC and ONR.

Liang, J.; Wang, J.; Dellas, N. S.; Cooley, B. J.; Mohney, S. E.; Engel-Herbert, R.; Chan, M. H. W.; Samarth, N.

2011-03-01

340

Elevated Temperature Dependent Transport Properties of As- and P-doped Zinc Oxide  

NASA Astrophysics Data System (ADS)

Achieving highly conductive p-type zinc oxide (ZnO) is desired for the development of ZnO based optoelectronic devices. Understanding electrical properties of ZnO, doped with p-type dopants, is necessary for improving p-type conductivity. We employed temperature dependent Hall effect measurement to study the electrical transport properties of As- and P-doped ZnO epilayers. The samples were grown on sapphire substrates by magnetron sputtering technique. From the Hall effect measurements performed at elevated temperatures ranging from 20 to 750 K, we observed double activation processes in both As- and P-doped ZnO epilayers. We will compare the results of uniform doped and delta-doped samples. Correlation between electrical properties from these Hall effect measurements and optical properties from low temperature photoluminescence measurements will also be discussed.

Cai, B.; Nakarmi, M. L.; Oder, T.; McMaster, M.; Smith, A.; Velpukonda, N.

2012-02-01

341

Anisotropic magnetism and spin-dependent transport in Co nanoparticle embedded ZnO thin films  

NASA Astrophysics Data System (ADS)

Oriented Co nanoparticles were obtained by Co ion implantation in crystalline ZnO thin films grown by pulsed laser deposition. Transmission electron microscopy revealed the presence of elliptically shaped Co precipitates with nanometer size, which are embedded in the ZnO thin films, resulting in anisotropic magnetic behavior. The low-temperature resistance of the Co-implanted ZnO thin films follows the Efros-Shklovskii type variable-range-hopping. Large negative magnetoresistance (MR) exceeding 10% is observed in a magnetic field of 1 T at 2.5 K and the negative MR survives up to 250 K (0.3%). The negative MR reveals hysteresis as well as anisotropy that correlate well with the magnetic properties, clearly demonstrating the presence of spin-dependent transport.

Li, D. Y.; Zeng, Y. J.; Pereira, L. M. C.; Batuk, D.; Hadermann, J.; Zhang, Y. Z.; Ye, Z. Z.; Temst, K.; Vantomme, A.; Van Bael, M. J.; Van Haesendonck, C.

2013-07-01

342

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

Microsoft Academic Search

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

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

1995-01-01

343

Temperature-Dependent Transport of Composite Fermions at Exactly ? = 1/2 Landau Level Filling^**  

NASA Astrophysics Data System (ADS)

We have studied the temperature dependent resistivity at exactly half Landau-level filling of a high-quality two-dimensional electron system in high magnetic field^1. The low-temperature transport at ? = 1/2 Landau-level filling is well parameterized by temperature dependent impurity and phonon scattering of a Fermi liquid of composite fermions with a mass m^*. The gauge field mediated composite fermion-phonon scattering contributes a T-3-dependence to the total mobility. The effective mass of composite fermions is obtained from the temperature dependence of composite fermion-impurity scattering and is somewhat larger than the the masses derived by Shubnikov-de Haas measurements away from half-filling^2,3. The resistivity at high temperatures can be well described by a softening of the composite fermion Fermi-edge. We also observe an anomalous increase in the effective mass under increased illumination at ? = 1/2. This can be understood as either resulting from a change in the effective interaction length between electrons or from decreased fluctuations which reduces the smearing of the divergence of the mass at exactly ? = 1/2. It is remarkable that the scattering behavior around ? = 1/2 can be described in such a simple single-particle picture. ^**Work done in collaboration with S. He, H.L. Stormer, L.N. Pfeiffer, K.W. West, and K.W. Baldwin, AT&T Bell Laboratories. ^1 W. Kang, S. He, H.L. Stormer, K.W. Baldwin, L.N. Pfeiffer, and K.W. West, Phys. Rev. Lett. 75, 4106 (1995). ^2H.C. Manoharan, M. Shayegan, and S.J. Klepper, Phys. Rev. Lett. 73, 3270 (1994). ^3 R.R. Du, H.L. Stormer, D.C. Tsui, A.S. Yeh, L.N. Pfeiffer, and K.W. West, Phys. Rev. Lett. 73, 3274 (1994).

Kang, Woowon

1996-03-01

344

Cyclin-dependent kinase 5 inhibitors: inhibition of dopamine transporter activity.  

PubMed

Cyclin-dependent kinase (Cdk) 5 reduces the rewarding properties of psychostimulants by dampening postsynaptic dopamine (DA) receptor signaling. Cdk5 is also present in midbrain DA neurons, where the DA transporter (DAT) is localized and limits DA neurotransmission by removing extracellular DA. Here, we tested the hypothesis that Cdk5 could also affect the disposition of DA by regulating DAT activity. Incubation of rat dorsal striatal (dSTR) synaptosomes with the Cdk5 inhibitors roscovitine, olomoucine, and 4-{[(7-oxo-6,7-dihydro-8H-[1,3]thiazolo[5,4-e]indol-8-ylidene)methyl]amino}-N-(2-pyridyl)benzenesulfonamide (GW8510) or the inactive congener iso-olomoucine resulted in a rapid, concentration-dependent inhibition of specific [3H]DA uptake. However, roscovitine was the only inhibitor that did not also decrease [3H]2beta-carbomethoxy-3beta-(4-fluorophenyl)tropane (WIN35,428) binding to dSTR DATs. Roscovitine-induced inhibition of dSTR [3H]DA uptake was explained by decreased maximal uptake velocity, without a change in cell-surface DAT levels. Roscovitine did not enhance [3H]DA release mediated by either DAT reverse-transport or Ca(2+) channels in dSTR slices. Instead, roscovitine enhanced spontaneous [3H]DA outflow and inhibited DAT-mediated [3H]DA reaccumulation into dSTR slices. To explore the involvement of Cdk5 in roscovitine-induced down-regulation of DAT activity, Cdk5 protein was knocked down via Cdk5-small interfering RNA by as much as 86% in porcine aortic endothelial cells stably expressing human (h)DATs. However, Cdk5 depletion did not alter hDAT activity. Taken together, our results suggest that roscovitine inhibits DAT activity independently of Cdk5; therefore, results obtained with such inhibitors should be interpreted with caution. Our study is the first to demonstrate that Cdk5 inhibitors reduce brain DAT activity via a mechanism that is independent of DAT trafficking and reverse-transport. PMID:19628755

Price, David A; Sorkin, Alexander; Zahniser, Nancy R

2009-07-23

345

Salt-dependent expression of a nitrate transporter and two amino acid transporter genes in Mesembryanthemum crystallinum.  

PubMed

Uptake and transport of inorganic nitrogen and allocation of amino acids are essential for plant growth and development. To study the effects of salinity on the regulation of transporters for nitrogenous compounds, we characterized the putative nitrate transporter McNRT1 and the amino acid transporters McAAT1 and McAAT2 from Mesembryanthemum crystallinum. By transcript analyses, McAAT1 was found in leaves, McAAT2 in roots, and McNRT1 in both tissues. By in situ PCR McNRT1 was localized, for example, to epidermal and vascular cells whereas McAAT2 was abundant in most cell types in mature roots and McAAT1 in the mesophyll and cells neighbouring xylem vessels in leaves. In response to salt stress, expression of McAAT2 and McNRT1 was stimulated in the root vasculature. In addition, McNRT1 and McAAT1 signals increased in the leaf phloem. Growth of yeast mutants deficient in histidine uptake was restored by McAAT2 whereas both McAAT1 and McAAT2 complemented a yeast mutant carrying a defect in proline uptake. The differential and cell-specific transcriptional activation of genes encoding nitrogen and amino acid transporters under salt stress suggest complex coordinated regulation of these transporter families to maintain uptake and distribution of nitrogenous compounds and amino acids under conditions of high salinity in plants. PMID:12956527

Popova, Olga V; Dietz, Karl-Josef; Golldack, Dortje

2003-06-01

346

Three ubiquitination sites of organic anion transporter-1 synergistically mediate protein kinase C-dependent endocytosis of the transporter.  

PubMed

Organic anion transporter-1 (OAT1) mediates the body disposition of a diverse array of clinically important drugs, including anti-HIV therapeutics, antitumor drugs, antibiotics, antihypertensives, and anti-inflammatories. Therefore, understanding the regulation of OAT1 has profound clinical significance. We previously established that OAT1 constitutively internalizes from and recycles back to cell surface and that activation of protein kinase C (PKC) inhibits OAT1 activity by promoting ubiquitination of the transporter, which then leads to an accelerated internalization of the transporter from cell surface to intracellular compartments. In the current study, we showed that PKC isoform PKC? was responsible for OAT1 ubiquitination. To directly address the role of OAT1 ubiquitination, we then generated two OAT1 mutants, each having multiple lysines (K) simultaneously mutated to arginine (R). One mutant K163/297/303/315/321R lost sensitivities to PKC-induced inhibition of transport activity, to PKC-induced ubiquitination, and to PKC-induced acceleration of transporter internalization. Further dissecting each lysine in this mutant, we identified Lys297, Lys303, and Lys315 as being the ubiquitin conjugation sites. Of interest, mutating any one of the three lysines prevented the ubiquitin conjugation to the other two lysines, suggesting that Lys297, Lys303, and Lys315 may form an optimal structure to interact with ubiquitination machineries. This is the first demonstration that Lys297, Lys303, and Lys315 play a synergistic role in PKC-regulated OAT1 ubiquitination, trafficking, and transport activity. PMID:23640180

Li, Shanshan; Zhang, Qiang; You, Guofeng

2013-05-02

347

Depth localized azimuthal anisotropy from SKS and P receiver functions: The Tien Shan  

NASA Astrophysics Data System (ADS)

Shear wave splitting in the seismic SKS phase provides a unique possibility to judge on deformations at depths inaccessible for direct observations. Fast S wave polarization direction in collisional belts is often parallel to the trend of the belt, although deformations of the mantle lithosphere in low-angle thrusts would lead to the fast polarization direction normal to the trend of the belt. These considerations suggested that the upper mantle in collisional belts is decoupled from the crust. However, SKS technique is notable by a poor depth resolution, and usually it assumes that the fast polarization direction is the same at any depth, which is hard to justify. Here, to investigate depth dependent azimuthal anisotropy in the mantle, we invert jointly P receiver functions and SKS particle motions at a number of seismograph stations. The technique involves azimuthal filtering of the receiver functions and provides a criterion to discriminate between the effects of azimuthal anisotropy and lateral heterogeneity of isotropic medium. A search for the optimum models is conducted with a technique similar to simulated annealing. Testing with synthetics demonstrates that this approach is robust. The results for 10 seismograph stations in the Tien Shan, the world's most active intracontinental collisional belt in Central Asia, reveal a pronounced change in the patterns of azimuthal anisotropy at a depth around 100 km. In the mantle lithosphere (at depths less than 100 km), anisotropy is relatively weak and fast wave polarization direction varies laterally in a broad range. This layer is not necessarily decoupled from the crust: its anisotropy can be a combined effect of present day thrusting and of deformations of the geologic past. In the lower layer (asthenosphere) the average azimuth of fast wave polarization is close to the trend of the belt, whereas magnitude of S wave anisotropy is stable and large (between 5 and 6 per cent). This anisotropy is a likely result of recent uniaxial shortening at right angle to the trend of the belt. At some stations the data require anisotropy in the crust. There is no evidence for anisotropy at depths exceeding 150-250 km.

Vinnik, L. P.; Aleshin, I. M.; Kiselev, S. G.; Kosarev, G. L.; Makeyeva, L. I.

2007-06-01

348

A new inverse problem based approach for azimuthal DOA estimation  

Microsoft Academic Search

We propose a novel algorithm to perform jointly the azimuthal direction-of-arrival (DOA) estimation and the multiuser detection (MUD) of signals impinging on an array of antennas. We treat the DOA estimation as an inverse problem of identifying a specific set of parameters that explains the received signal for a suitable physical model. We reformulate the estimation problem as a highly

Raja D. Balakrishnan; Hyuck M. Kwon

2003-01-01

349

QCD coherence studies using two particle azimuthal correlations  

Microsoft Academic Search

From a sample of 146900 hadronicZ0 decays recorded by the OPAL detector at LEP, we have studied the azimuthal correlations of particles in hadronic events. It is expected that these correlations are sensitive to interference effects in QCD. We have compared the data to QCD Monte Carlo models which include and which do not include interference effects. We find that

P. D. Acton; G. Alexander; J. Allison; P. P. Allport; K. J. Anderson; S. Arcelli; A. Astbury; D. Axen; G. Azuelos; G. A. Bahan; J. T. M. Baines; A. H. Ball; J. Banks; R. J. Barlow; S. Barnett; J. R. Batley; G. Beaudoin; A. Beck; J. Becker; T. Behnke; K. W. Bell; G. Bella; P. Berlich; S. Bethke; O. Biebel; U. Binder; I. J. Bloodworth; P. Bock; B. Boden; H. M. Bosch; S. Bougerolle; H. Breuker; R. M. Brown; A. Buijs; H. J. Burckardt; C. Burgard; P. Capiluppi; R. K. Carnegie; A. A. Carter; J. R. Carter; C. Y. Chang; D. G. Charlton; P. E. L. Clarke; I. Cohen; J. C. Clayton; W. J. Collins; J. E. Conboy; M. Cooper; M. Coupland; M. Cuffiani; S. Dado; G. M. Dallavalle; S. De Jong; L. A. del Pozo; H. Deng; A. Dieckmann; M. Dittmar; M. S. Dixit; E. do Couto e Silva; J. E. Duboscq; E. Duchovni; G. Duckeck; I. P. Duerdoth; D. J. P. Dumas; P. A. Elcombe; P. G. Estabrooks; E. Etzion; H. G. Evans; F. Fabbri; M. Fincke-Keeler; H. M. Fischer; D. G. Fong; M. Foucher; A. Gaidot; O. Ganel; J. W. Gary; J. Gascon; R. F. McGowan; N. I. Geddes; C. Geich-Gimbel; S. W. Gensler; F. X. Gentit; G. Giacomelli; V. Gibson; W. R. Gibson; J. D. Gillies; J. Goldberg; M. J. Goodrick; W. Gorn; C. Grandi; F. C. Grant; J. Hagemann; G. G. Hanson; M. Hansroul; C. K. Hargrove; P. F. Harrison; J. Hart; P. M. Hattersley; M. Hauschild; C. M. Hawkes; E. Heflin; R. J. Hemingway; R. D. Heuer; J. C. Hill; S. J. Hillier; T. Hilse; D. A. Hinshaw; J. D. Hobbs; P. R. Hobson; D. Hochman; R. J. Homer; A. K. Honma; C. P. Howarth; R. E. Hughes-Jones; R. Humbert; P. Igo-Kemenes; H. Ihssen; D. C. Imrie; A. C. Janissen; A. Jawahery; P. W. Jeffreys; H. Jeremie; M. Jimack; M. Jobes; R. W. L. Jones; P. Jovanovic; C. Jui; D. Karlen; K. Kawagoe; T. Kawamoto; R. K. Keeler; R. G. Kellogg; B. W. Kennedy; S. Kluth; T. Kobayashi; T. P. Kokott; S. Komamiya; L. Köpke; J. F. Kral; R. Kowalewski; J. von Krogh; J. Kroll; M. Kuwano; P. Kyberd; G. D. Lafferty; F. Lamarche; J. G. Layter; P. Le Du; P. Leblanc; A. M. Lee; M. H. Lehto; D. Lellouch; P. Lennert; C. Leroy; J. Letts; S. Levergrün; L. Levinson; S. L. Lloyd; F. K. Loebinger; J. M. Lorah; B. Lorazo; M. J. Losty; X. C. Lou; J. Ludwig; M. Mannelli; S. Marcellini; G. Maringer; C. Markus; A. J. Martin; J. P. Martin; T. Mashimo; P. Mättig; U. Maur; J. McKenna; T. J. McMahon; J. R. McNutt; F. Meijers; D. Menszner; F. S. Merritt; H. Mes; A. Michelini; R. P. Middleton; G. Mikenberg; J. Mildenberger; D. J. Miller; R. Mir; W. Mohr; C. Moisan; A. Montanari; T. Mori; M. Morii; T. Mouthuy; B. Nellen; H. H. Nguyen; M. Nozaki; S. W. O'Neale; F. G. Oakham; F. Odorici; H. O. Ogren; C. J. Oram; M. J. Oreglia; S. Orito; J. P. Pansart; B. Panzer-Steindel; P. Paschievici; G. N. Patrick; N. Paz-Jaoshvili; P. Pfister; J. E. Pilcher; D. Pitman; D. E. Plane; P. Poffenberger; B. Poli; A. Pouladdej; E. Prebys; T. W. Pritchard; H. Przysiezniak; G. Quast; M. W. Redmond; D. L. Rees; G. E. Richards; D. Robinson; A. Rollnik; J. M. Roney; E. Ros; S. Rossberg; A. M. Rossi; M. Rosvick; P. Routenburg; K. Runge; O. Runolfsson; D. R. Rust; M. Sasaki; C. Sbarra; A. D. Schaile; O. Schaile; W. Schappert; P. Scharff-Hansen; P. Schenk; H. von der Schmitt; S. Schreiber; C. Schwick; J. Schwiening; W. G. Scott; M. Settles; T. G. Shears; B. C. Shen; C. H. Shepherd-Themistocleous; P. Sherwood; R. Shypit; A. Simon; P. Singh; G. P. Siroli; A. Skuja; A. M. Smith; T. J. Smith; G. A. Snow; R. Sobie; R. W. Springer; M. Sproston; K. Stephens; J. Steuerer; R. Ströhmer; D. Strom; T. Takeshita; P. Taras; S. Tarem; M. Tecchio; P. Teixeira-Dias; N. Tesch; N. J. Thackray; G. Transtromer; N. J. Tresilian; T. Tsukamoto; M. F. Turner; G. Tysarczyk-Niemeyer; D. Van den Plas; R. van Kooten; G. J. VanDalen; G. Vasseur; C. J. Virtue; A. Wagner; D. L. Wagner; C. Wahl; J. P. Walker; C. P. Ward; D. R. Ward; P. M. Watklins; A. T. Watson; N. K. Watson; M. Weber; P. Weber; S. Weisz; P. S. Wells; N. Wermes; M. A. Whalley; G. W. Wilson; J. A. Wilson; V. H. Winterer; T. Wlodek; S. Wotton; T. R. Wyatt; R. Yaari; A. Yeaman; G. Yekutieli; M. Yurko; W. Zeuner; G. T. Zorn

1993-01-01

350

Microwave Landing System (MLS) Back Azimuth Operational Issues Flight Tests.  

National Technical Information Service (NTIS)

This test plan describes a series of flight tests using Microwave Landing System (MLS) back azimuth guidance for missed approach and departure procedures. Issues to be addressed during these flight tests are: (1) The proper point in a missed approach to s...

E. J. Pugacz

1990-01-01

351

Azimuthal pressure gradient as driving force of substorm currents  

Microsoft Academic Search

We have studied the azimuthal pressure gradient in the central plasma sheet during substorms using plasma and magnetic field data obtained by the AMPTE\\/IRM satellite at nightside in radial distances of 9-15 RE. The pressure gradient is statistically estimated for the interval when the magnetic field shows a dipolar configuration (elevation angle >45°). It is found that by this criterion,

K. Shiokawa; G. Haerendel; W. Baumjohann

1998-01-01

352

Azimuthally anisotropic model of the oceanic upper mantle  

Microsoft Academic Search

A mixed form of forward and backward modelings of azimuthally anisotropic oceanic upper mantle is attempted for a data set of surface-wave velocities of periods 30-100 s. One of the basic configurations of the anisotropy postulated in the LID and LVZ is axial symmetry of elastic properties with a horizontal axis parallel to the spreading direction as found in ultramafic

Ichiro Kawasaki

1986-01-01

353

A Comparison of Techniques for Achieving Fine Azimuth Resolution  

Microsoft Academic Search

In the discussion of techniques for achieving azimuth resolution, it is instructive to compare the achievable resolution for three cases: 1) the conventional case for which ¿R Res = k ¿ D 2) the unfocussed synthetic antenna case for which Res = k¿¿R 3) the focussed synthetic antenna case for which Res = kD where ¿ is wavelength, D is

L. J. Cutrona; G. O. Hall

1962-01-01

354

Azimuth\\/elevation direction finding using regular array geometries  

Microsoft Academic Search

The authors consider the problem of extending the estimation of signal parameters via rotational invariance techniques (ESPRIT) algorithm for multiple source, cochannel direction finding to the two-dimensional case (e.g., azimuth and elevation angle estimation). Two algorithms are presented, one based on the optimal (minimal variance) subspace fitting formulation of ESPRIT, and the other based on an approximation to it. The

A. L. Swindlehurst; Thomas Kailath

1993-01-01

355

The Jakes fading model for antenna arrays incorporating azimuth spread  

Microsoft Academic Search

A new method for simulating the multiplicative fading of the narrow-band, flat wireless channel for antenna array receivers is presented. The new approach produces a set of fading waveforms, one waveform associated with each receiver element, in which the waveforms are appropriately correlated to take into account the spread, or dispersion, in the azimuth (arrival angle) of the received signal.

Tracy L. Fulghum; Karl J. Molnar; Alexandra Duel-Hallen

2002-01-01

356

Polarimetric SAR data compensation for terrain azimuth slope variation  

Microsoft Academic Search

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

Jong-Sen Lee; Dale L. Schuler; Thomas L. Ainsworth

2000-01-01

357

Electromagnetic wave spectrum in an azimuthally gyrotropic medium  

Microsoft Academic Search

Maxwell equations are applied to monochromatic electromagnetic waves in an azimuthally gyrotropic medium, and solutions corresponding to axial wave propagation are derived. When the axial restriction is lifted, the field configuration is found to be similar to that of undamped waves in open waveguides, and the propagation-constant spectrum is infinite at a fixed frequency. It is shown by examples for

Iu. M. Terentev

1979-01-01

358

Azimuthal seismic anisotropy constrains net rotation of the lithosphere  

Microsoft Academic Search

Net rotation (NR) of the lithosphere is found in hot spot reference frames, important for tectonics and plume models, but difficult to constrain. Using mantle flow and crystallographic texture modeling, I show that NRs lead to mantle shearing which is recorded in azimuthal seismic anisotropy. The NR amplitude in some hot spot models is so large that it degrades the

T. W. Becker

2008-01-01

359

Azimuthal correlations and alignment of particles in gamma families  

SciTech Connect

Azimuthal angular correlations and the alignment of photons are studied in gamma families recorded by the Pamir Collaboration in a carbon x-ray emulsion chamber. The present interpretation of these experimental data is based on a model of semihard parton scattering in nucleon-nucleus collisions and on arguments favoring the production of exotic beam strings and heavy leading resonances undergoing quasicoplanar decays.

Yuldashbaev, T. S., E-mail: tsju@uzsci.net; Chudakov, V. M.; Nuritdinov, Kh. [Uzbek Academy of Sciences, Institute for Physics and Technology, Fizika-Solntse Research and Production Association (Uzbekistan)

2008-11-15

360

Precision continuous high-strength Azimuth track for large telescopes  

Microsoft Academic Search

A novel track joint was developed for the azimuth track of the 50-m diameter Large Millimeter Telescope (LMT) now under construction in Mexico at an elevation of 4,600 m. The track, which is 430 mm wide by 230 mm deep, must be flat to within +\\/- 0.3 mm, and the material hardness at least 290 Brinell. This design uses a

Joseph Antebi; Frank W. Kan

2003-01-01

361

Azimuthal decorrelation of forward jets in deep inelastic scattering  

SciTech Connect

We study the azimuthal angle decorrelation of forward jets in deep inelastic scattering. We make predictions for this observable at HERA describing the high energy limit of the relevant scattering amplitudes with quasi-multi-Regge kinematics together with a collinearly-improved evolution kernel for multiparton emissions.

Sabio Vera, Agustin [Physics Department, Theory Division, CERN, CH-1211, Geneva 23 (Switzerland); Schwennsen, Florian [II. Institut fuer Theoretische Physik, Universitaet Hamburg, Luruper Chaussee 149, D-22761 Hamburg (Germany)

2008-01-01

362

Azimuthal velocity variations caused by borehole stress concentrations  

Microsoft Academic Search

In laboratory experiments, borehole stress concentrations caused by far-field uniaxial stress produce measurable variations in compressional wave velocities near the borehole. Uniaxial stress was applied perpendicular to the axis of a borehole drilled through a sandstone block. Inside the fluid-filled borehole, refracted compressional waves were propagated in the rock parallel to the borehole axis at discrete azimuths, producing a scan

Kenneth W. Winkler

1996-01-01

363

Resolvability Analysis of Single Azimuth Seismic Moment Tensor Inversion  

Microsoft Academic Search

Summary Microseismicity monitoring of hydraulic fractures is frequently done with a single azimuth observational geometry with receivers deployed in a vertical array. The latter restricts the solutions that we are capable to retrieve and can hide the existence of non-deviatoric sources (Vavrycuk, 2007). The complete recovering of the source mechanisms is an important aspect for the understanding of induced fracturing

Ismael Vera Rodriguez; Mauricio D. Sacchi

2009-01-01

364

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

NASA Astrophysics Data System (ADS)

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).

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

2008-05-01

365

Measurement of azimuthal asymmetries of the unpolarized cross section at HERMES  

SciTech Connect

A multi-dimensional (x, y, z, P{sub hperpendicular}) extraction of cos {phi}{sub h} and cos 2{phi}{sub h} azimuthal asymmetries of unpolarized Semi-Inclusive Deep Inelastic Scattering at HERMES is discussed. The use of data taken with hydrogen and deuterium targets and the separation of positive and negative hadrons allow to access flavor-dependent information about quark intrinsic transverse momenta and spin-orbit correlations. This flavor sensitivity allows for a discrimination between theoretical models in the HERMES kinematic regime.

Giordano, Francesca [INFN and Universita degli studi di Ferrara (Italy); Lamb, Rebecca [University of Illinois (United States)

2009-08-04

366

Post mortem changes in Ca2+ transporting proteins of sarcoplasmic reticulum in dependence on malignant hyperthermia status in pigs  

Microsoft Academic Search

Meat quality of pigs is dependent on biochemical and biophysical processes in the time course post mortem (p.m.) and is associated with the intracellular Ca2+ homeostasis. However, there is little known about changes in the Ca2+ transporting proteins controlling the Ca2+ uptake of sarcoplasmic reticulum (SR) in the time course p.m. In this study changes in the Ca2+ transporting proteins

Ulrich Küchenmeister; Gerda Kuhn; Jochen Wegner; Gerd Nürnberg; Klaus Ender

1999-01-01

367

Effects of symmetry and Stone-Wales defect on spin-dependent electronic transport in zigzag graphene nanoribbons  

Microsoft Academic Search

Spin-dependent electronic transport properties in zigzag graphene nanoribbons (ZGNRs) are studied using first-principles quantum transport calculations. The effects of the symmetry and defect have been considered. The results show that when the spin polarization is considered, both symmetric and asymmetric ZGNRs present semiconductor behavior, which is different from spin-unpolarized result. The symmetry of ZGNRs plays an important role in electron

Yun Ren; Ke-Qiu Chen

2010-01-01

368

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

PubMed

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

Wall, Mark J; Dale, Nicholas

2013-05-27

369

Structural, electronic, magnetic and spin dependent transport properties of Fe/CaS/Fe (001) heterostructures  

NASA Astrophysics Data System (ADS)

Structural, electronic, and magnetic properties of Fe/CaS (001) interfaces and Fe/CaS/Fe (001) heterostructures have been studied by means of a self-consistent Green's function technique for surface and interfaces implemented within the tight-binding linear muffin-tin orbital formalism. Spin dependent transport properties of the Fe/CaS/Fe (001) tunnel junctions with thin and intermediate barriers, in the current-perpendicular-to-plane geometry, have been determined by means of Kubo-Landauer approach implemented within the tight-binding linear muffin-tin orbital formalism. A small charge rearrangement is evidenced at the Fe/CaS (001) interfaces. The iron interfacial magnetic moments are enhanced over the bulk value. A small exchange coupling with the sign depending on the Fe/CaS (001) interface geometric structure and the strength decaying exponentially with the barrier is evidenced. Interfacial charge transfer, interface iron magnetic moments, and tunneling currents are sensitive to the interfacial structure. Interface resonant states have a decisive role in the tunneling process and the main contribution to the current in the ferromagnetic state of the junction is given by the minority-spin electrons.

Vlaic, P.; Burzo, E.; Carva, K.

2013-02-01

370

Dopamine transporter-dependent and -independent actions of trace amine beta-phenylethylamine.  

PubMed

Beta-phenylethylamine (beta-PEA) is an endogenous amine that is found in trace amounts in the brain. It is believed that the locomotor-stimulating action of beta-PEA, much like amphetamine, depends on its ability to increase extracellular dopamine (DA) concentrations owing to reversal of the direction of dopamine transporter (DAT)-mediated DA transport. beta-PEA can also bind directly to the recently identified G protein-coupled receptors, but the physiological significance of this interaction is unclear. To assess the mechanism by which beta-PEA mediates its effects, we compared the neurochemical and behavioral effects of this amine in wild type (WT), heterozygous and 'null' DAT mutant mice. In microdialysis studies, beta-PEA, administered either systemically or locally via intrastriatal infusion, produced a pronounced outflow of striatal DA in WT mice whereas no increase was detected in mice lacking the DAT (DAT-KO mice). Similarly, in fast-scan voltammetry studies beta-PEA did not alter DA release and clearance rate in striatal slices from DAT-KO mice. In behavioral studies beta-PEA produced a robust but transient increase in locomotor activity in WT and heterozygous mice. In DAT-KO mice, whose locomotor activity and stereotypy are increased in a novel environment, beta-PEA (10-100 mg/kg) exerted a potent inhibitory action. At high doses, beta-PEA induced stereotypies in WT and heterozygous mice; some manifestations of stereotypy were also observed in the DAT-KO mice. These data demonstrate that the DAT is required for the striatal DA-releasing and hyperlocomotor actions of beta-PEA. The inhibitory action on hyperactivity and certain stereotypies induced by beta-PEA in DAT-KO mice indicate that targets other than the DAT are responsible for these effects. PMID:15447669

Sotnikova, Tatyana D; Budygin, Evgeny A; Jones, Sara R; Dykstra, Linda A; Caron, Marc G; Gainetdinov, Raul R

2004-10-01

371

ATP-dependent calcium transport in plasma membrane vesicles from neutrophil leukocytes.  

PubMed

Plasma membrane vesicles were prepared from guinea pig peritoneal exudate neutrophils, using nitrogen cavitation to rupture the plasma membrane and differential centrifugation to separate the vesicles. The vesicles were enriched 13.2-fold in (Na+, K+)-ATPase activity and had a cholesterol:protein ratio of 0.15, characteristic of plasma membranes. Contamination of the vesicle preparation with DNA or marker enzyme activities for intracellular organelles was very low. Studies designed to determine vesicle sidedness and integrity indicated that 33% were sealed, inside-out; 41% were sealed, right side-out, and 26% were leaky. The vesicles accumulated 45Ca2+ in a linear fashion for 45 min. The uptake was dependent on the presence of oxalate and MgATP in the incubating medium. Uptake showed a Ka for free Ca2+ of 164 nM and a Vmax of 17.2 nmol/mg . min (based on total protein). GTP, ITP, CTP, UTP, ADP, or AMP supported uptake at rates less than or equal to 11% of ATP. Ca2+ uptake was maximal at pH 7-7.5. Calcium stimulated the hydrolysis of ATP by the vesicles with a Ka for free Ca2+ of 440 nM and Vmax of 17.5 nmol/mg . min (based on total protein). When the Ca2+ uptake rate was based upon those vesicles expected to transport Ca2+ (33% sealed, inside-out vesicles) and Ca2+-stimulated ATPase activity was based upon those vesicles expected to express that activity (26% leaky + 33% sealed, inside-out vesicles), the molar stoichiometry of Ca2+ transported:ATP hydrolyzed was 2.12 +/- 0.12. Calmodulin did not increase either Vmax or Ka for free Ca2+ of the uptake system in the vesicles, even when they were treated previously with ethylene glycol bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid. The high affinity of this system for Ca2+, specificity for ATP, physiological pH optimum, and stoichiometry of Ca2+ transported:ATP hydrolyzed suggest that it represents an important mechanism by which neutrophils maintain low levels of cytoplasmic free Ca2+. PMID:6309768

Ochs, D L; Reed, P W

1983-08-25

372

TRANSPORT  

EPA Science Inventory

Presentation outline: transport principles, effective solubility; gasoline composition; and field examples (plume diving). Presentation conclusions: MTBE transport follows from - phyiscal and chemical properties and hydrology. Field examples show: MTBE plumes > benzene plu...

373

Synaptic uptake and beyond: the sodium- and chloride-dependent neurotransmitter transporter family SLC6  

Microsoft Academic Search

The SLC6 family is a diverse set of transporters that mediate solute translocation across cell plasma membranes by coupling solute transport to the cotransport of sodium and chloride down their electrochemical gradients. These transporters probably have 12 transmembrane domains, with cytoplasmic N- and C-terminal tails, and at least some may function as homo-oligomers. Family members include the transporters for the

Nian-Hang Chen; Maarten E. A. Reith; Michael W. Quick

2004-01-01

374

Super-channel in bacteria: function and structure of the macromolecule import system mediated by a pit-dependent ABC transporter  

Microsoft Academic Search

In a soil isolate, Sphingomonas sp. A1, the transport of a macromolecule (alginate: 27 kDa) is mediated by a pit-dependent ATP-binding cassette (ABC) transporter. The transporter is different from other ABC transporters so far analyzed in that its function is dependent on a pit, a mouth-like organ formed on the cell surface only when cells are compelled to assimilate macromolecules,

Yumiko Mishima; Keiko Momma; Wataru Hashimoto; Bunzo Mikami; Kousaku Murata

2001-01-01

375

Transportation  

Microsoft Academic Search

This paper presents a strategic-level examination of the transportation industry - an industry vital to national prosperity and security. Because the defense sector relies on commercial transportation for both peacetime activities and for power projection, senior military leaders must understand the global transportation industry and the environment in which the private sector operates. They must also assess the role of

Peter Hall; Mohammed Al-Adwan; Dennis M. Brogan; William J. Flannery; Gregory L. Gardner; Elizabeth J. Gilleo; Robert A. Hall; Peter C. Hunt; Nathan M. Kathir; Timothy M. McKeithen; Evan M. Miller; E. Mlikan; Ruben Perales; Lawrence J. Pleis; Paul M. Smith; Paul Needham; Steve Ditmeyer

1969-01-01

376

Binaurality and azimuth tuning of neurons in the auditory cortex of the big brown bat  

Microsoft Academic Search

By using a combined closed and free-field stimulation system, binaurality and azimuth tuning of the neurons in the auditory\\u000a cortex of the big brown bat,Eptesicus fuscus, were studied. A variety of azimuth-tuning functions were demonstrated for the binaural neurons. The large majority of EE\\u000a (contralateral and ipsilateral excitatory) neurons exhibited azimuth selectivity with the best azimuths (BA) at contralateral\\u000a 30°–40°,

Junxian Shen; Qicai Chen

2002-01-01

377

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

PubMed

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

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

2008-10-07

378

GTP-dependent Binding and Nuclear Transport of RNA Polymerase II by Npa3 Protein*  

PubMed Central

We identified XAB1 in a proteomic screen for factors that interact with human RNA polymerase II (RNAPII). Because XAB1 has a conserved Saccharomyces cerevisiae homologue called Npa3, yeast genetics and biochemical analysis were used to dissect the significance of the interaction. Degron-dependent Npa3 depletion resulted in genome-wide transcription decreases, correlating with a loss of RNAPII from genes as measured by chromatin immunoprecipitation. Surprisingly, however, transcription in vitro was unaffected by Npa3, suggesting that it affects a process that is not required for transcription in yeast extracts. Indeed, Npa3 depletion in vivo affects nuclear localization of RNAPII; the polymerase accumulates in the cytoplasm. Npa3 is a member of the GPN-LOOP family of GTPases. Npa3 mutants that either cannot bind GTP or that bind but cannot hydrolyze it are inviable and unable to support nuclear transport of RNAPII. Surprisingly, we were unable to detect interactions between Npa3 and proteins in the classical importin ?/? pathway for nuclear import. Interestingly, Npa3-RNAPII binding is significantly increased by the addition of GTP or its slowly hydrolyzable analogue guanosine 5?-3-O-(thio)triphosphate (GTP?S). Moreover, the Npa3 mutant that binds GTP, but cannot hydrolyze it, binds RNAPII even in the absence of added GTP, whereas the mutant that cannot bind GTP is unable to bind the polymerase. Together, our data suggest that Npa3 defines an unconventional pathway for nuclear import of RNAPII, which involves GTP-dependent binding of Npa3 to the polymerase.

Staresincic, Lidija; Walker, Jane; Dirac-Svejstrup, A. Barbara; Mitter, Richard; Svejstrup, Jesper Q.

2011-01-01

379

Activation of cAMP-dependent signaling pathway induces mouse organic anion transporting polypeptide 2 expression.  

PubMed

Rodent Oatp2 is a hepatic uptake transporter for such compounds as cardiac glycosides. In the present study, we found that fasting resulted in a 2-fold induction of Oatp2 expression in liver of mice. Because the cAMP-protein kinase A (PKA) signaling pathway is activated during fasting, the role of this pathway in Oatp2 induction during fasting was examined. In Hepa-1c1c7 cells, adenylyl cyclase activator forskolin as well as two cellular membrane-permeable cAMP analogs, dibutyryl cAMP and 8-bromo-cAMP, induced Oatp2 mRNA expression in a time- and dose-dependent manner. These three chemicals induced reporter gene activity in cells transfected with a luciferase reporter gene construct containing a 7.6-kilobase (kb) 5'-flanking region of mouse Oatp2. Transient transfection of cells with 5'-deletion constructs derived from the 7.6-kb Oatp2 promoter reporter gene construct, as well as 7.6-kb constructs in which a consensus cAMP response element (CRE) half-site CGTCA (-1808/-1804 bp) was mutated or deleted, confirms that this CRE site was required for the induction of luciferase activity by forskolin. Luciferase activity driven by the Oatp2 promoter containing this CRE site was induced in cells cotransfected with a plasmid encoding the protein kinase A catalytic subunit. Cotransfection of cells with a plasmid encoding the dominant-negative CRE binding protein (CREB) completely abolished the inducibility of the reporter gene activity by forskolin. In conclusion, induction of Oatp2 expression in liver of fasted mice may be caused by activation of the cAMP-dependent signaling pathway, with the CRE site (-1808/-1804) and CREB being the cis- and trans-acting factors mediating the induction, respectively. PMID:17244698

Chen, Chuan; Cheng, Xingguo; Dieter, Matthew Z; Tanaka, Yuji; Klaassen, Curtis D

2007-01-23

380

GTP-dependent binding and nuclear transport of RNA polymerase II by Npa3 protein.  

PubMed

We identified XAB1 in a proteomic screen for factors that interact with human RNA polymerase II (RNAPII). Because XAB1 has a conserved Saccharomyces cerevisiae homologue called Npa3, yeast genetics and biochemical analysis were used to dissect the significance of the interaction. Degron-dependent Npa3 depletion resulted in genome-wide transcription decreases, correlating with a loss of RNAPII from genes as measured by chromatin immunoprecipitation. Surprisingly, however, transcription in vitro was unaffected by Npa3, suggesting that it affects a process that is not required for transcription in yeast extracts. Indeed, Npa3 depletion in vivo affects nuclear localization of RNAPII; the polymerase accumulates in the cytoplasm. Npa3 is a member of the GPN-LOOP family of GTPases. Npa3 mutants that either cannot bind GTP or that bind but cannot hydrolyze it are inviable and unable to support nuclear transport of RNAPII. Surprisingly, we were unable to detect interactions between Npa3 and proteins in the classical importin ?/? pathway for nuclear import. Interestingly, Npa3-RNAPII binding is significantly increased by the addition of GTP or its slowly hydrolyzable analogue guanosine 5'-3-O-(thio)triphosphate (GTP?S). Moreover, the Npa3 mutant that binds GTP, but cannot hydrolyze it, binds RNAPII even in the absence of added GTP, whereas the mutant that cannot bind GTP is unable to bind the polymerase. Together, our data suggest that Npa3 defines an unconventional pathway for nuclear import of RNAPII, which involves GTP-dependent binding of Npa3 to the polymerase. PMID:21844196

Staresincic, Lidija; Walker, Jane; Dirac-Svejstrup, A Barbara; Mitter, Richard; Svejstrup, Jesper Q

2011-08-15

381

Hydrogen peroxide induces loss of dopamine transporter activity: a calcium-dependent oxidative mechanism.  

PubMed

H2O2 dose dependently inhibited dopamine uptake in PC12 cells and in striatal synaptosomes. Treatment with H2O2 resulted in a reversible reduction in Vmax, with no effect on its Km value. This suppressive effect of H2O2 could be relieved by reducing agents (dithiothreitol and cysteine). Furthermore, an oxidizer (dithiodipyridine) also markedly suppressed the dopamine transporter (DAT). Oxidative stress therefore might contribute to the action of H2O2. H2O2 appeared to modify DAT at both extracellular and intracellular sites because cumene-H2O2 (a radical generator mostly restricted to plasma membranes) at high concentrations also slightly suppressed DAT activity and the intracellular overexpression of catalase ameliorated the inhibitory effect of H2O2. Internalization was unlikely to be involved because concanavalin A, which blocked endocytosis, did not prevent the H2O2-evoked inhibition of DAT activity. Interestingly, H2O2 treatment evoked a Ca2+ influx in PC12 cells. Moreover, removal of external calcium by EGTA or reduction in the intracellular calcium level using BAPTA-AM reversed the inhibitory effect of H2O2. Conversely, depletion of intracellular calcium stores using thapsigargin did not affect the reduction in DAT activity by H2O2. Collectively, our results indicate that the DAT, one of the most important proteins controlling the dopaminergic system, is also a redox sensor. In addition, H2O2 might suppress the DAT by a Ca2+-dependent oxidative pathway. PMID:12911632

Huang, Chuen-Lin; Huang, Nai-Kuei; Shyue, Song-Kun; Chern, Yijuang

2003-09-01

382

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

SciTech Connect

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.

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

383

Association of DNA Polymorphisms in the Synaptic Vesicular Amine Transporter Gene (SLC18A2) with Alcohol and Nicotine Dependence  

Microsoft Academic Search

The brain synaptic vesicular amine transporter SLCA18A2 is a key component for the uptake of monoamines like dopamine or serotonin into vesicles. We have analyzed seven DNA polymorphisms located in the genomic region of SLC18A2 for association with alcohol- and nicotine dependence, using a family-based design. Our sample comprised 131 families with alcohol-dependent offspring and 96 families with at least

Sibylle G Schwab; Petra E Franke; Barbara Hoefgen; Vera Guttenthaler; Dirk Lichtermann; Matyas Trixler; Michael Knapp; Wolfgang Maier; Dieter B Wildenauer

2005-01-01

384

Synaptic uptake and beyond: the sodium- and chloride-dependent neurotransmitter transporter family SLC6.  

PubMed

The SLC6 family is a diverse set of transporters that mediate solute translocation across cell plasma membranes by coupling solute transport to the cotransport of sodium and chloride down their electrochemical gradients. These transporters probably have 12 transmembrane domains, with cytoplasmic N- and C-terminal tails, and at least some may function as homo-oligomers. Family members include the transporters for the inhibitory neurotransmitters GABA and glycine, the aminergic transmitters norepinephrine, serotonin, and dopamine, the osmolytes betaine and taurine, the amino acid proline, and the metabolic compound creatine. In addition, this family includes a system B(0+) cationic and neutral amino acid transporter, and two transporters for which the solutes are unknown. In general, SLC6 transporters act to regulate the level of extracellular solute concentrations. In the central and the peripheral nervous system, these transporters can regulate signaling among neurons, are the sites of action of various drugs of abuse, and naturally occurring mutations in several of these proteins are associated with a variety of neurological disorders. For example, transgenic animals lacking specific aminergic transporters show profoundly disturbed behavioral phenotypes and probably represent excellent systems for investigating psychiatric disease. SLC6 transporters are also found in many non-neural tissues, including kidney, intestine, and testis, consistent with their diverse physiological roles. Transporters in this family represent attractive therapeutic targets because they are subject to multiple forms of regulation by many different signaling cascades, and because a number of pharmacological agents have been identified that act specifically on these proteins. PMID:12719981

Chen, Nian-Hang; Reith, Maarten E A; Quick, Michael W

2003-04-29

385

Azimuthal Asymmetry and Transverse Momentum of Hadrons in Deep Inelastic Muon Scattering at 490 GEV.  

NASA Astrophysics Data System (ADS)

The forward charged hadrons produced in deep inelastic scattering of 490 GeV muons from deuterium were studied. The data were taken by the E665 collaboration during the 1987 -1988 Fermilab fixed target run. 3 times 10^4 events (6 times 10^4 hadrons) were collected over a large range of kinematic variables: 100 GeV < nu < 500 GeV, 2 GeV^2 < Q^2 < 100 GeV ^2, 0.003 < x_{Bj } < 0.2, and 0.2 < y_ {Bj} < 0.9. Using the virtual photon axis as the z-axis, the distributions of the produced hadrons in azimuthal angle and in transverse momentum are examined. The primordial k_{|} of the struck patron and {cal O}(alpha _{S}) QCD effects are expected to contribute to an azimuthal asymmetry and to an increase in the average transverse momentum. Some theoretical work in the literature concerning these effects is described and some original results are derived concerning the effects of primordial k_{|} on the azimuthal distribution. A Monte Carlo program is described which includes these theoretical effects and models fragmentation, the detector response, and the event reconstruction. The data exhibit several surprising effects. First, the phi asymmetry in the data is independent of Q ^2, while theoretically it should be more pronounced at low Q^2 and vanish at high Q^2. Second, the phi asymmetry is carried by the most energetic particle in each event, which we call the Rank 1 particle, and there is very little phi asymmetry of the other charged hadrons. Third, this phi asymmetry in the Rank 1 particle is independent of the hadron energy fraction z_{h} . The Monte Carlo predicts a strong z_ {h} dependence and little rank dependence. Finally, the seagull plot shows an unexpected increase in transverse momentum p_{T} for high energy hadrons (z_{h} > 0.4) as a function of Q^2. It is clear from these results that more theoretical work is needed in order to understand primordial k_ {|} and the azimuthal asymmetry in deep inelastic scattering. (Copies available exclusively from MIT Libraries, Rm. 14-0551, Cambridge, MA 02139-4307. Ph. 617 -253-5668; Fax 617-253-1690.).

Baker, Mark David

386

Time Sequence Diffeomorphic Metric Mapping and Parallel Transport Track Time-Dependent Shape Changes  

PubMed Central

Serial MRI human brain scans have facilitated the detection of brain development and of the earliest signs of neuropsychiatric and neurodegenerative diseases, monitoring disease progression, and resolving drug effects in clinical trials for preventing or slowing the rate of brain degeneration. To track anatomical shape changes in serial images, we introduce new point-based time sequence large deformation diffeomorphic metric mapping (TS-LDDMM) to infer the time flow of within-subject geometric shape changes that carry known observations through a period. Its Euler-Lagrange equation is generalized for anatomies whose shapes are characterized by point sets, such as landmarks, curves, and surfaces. The time-dependent momentum obtained from the TS-LDDMM encodes within-subject shape changes. For the purpose of across-subject shape comparison, we then propose a diffeomorphic analysis framework to translate within-subject deformation in a global template without incorporating across-subject anatomical variations via parallel transport technique. The analysis involves the retraction of the within-subject timedependent momentum along the TS-LDDMM trajectory from each time to the baseline, the translation of the momentum in a global template, and the reconstruction of the TS-LDDMM trajectory starting from the global template.

Qiu, Anqi; Albert, Marilyn; Younes, Laurent; Miller, Michael I.

2009-01-01

387

Concentration Dependent Colloid Transport in Saturated Porous Media: The Role of Solution Chemistry  

NASA Astrophysics Data System (ADS)

Recent experimental and theoretical work has demonstrated that colloid retention under unfavorable attachment conditions mainly occurs in the smallest regions of the pore space near grain-grain contacts, in small pore throats, and in hydrodynamically isolated low velocity regions. Colloid retention in these locations is a highly coupled process that depends on the system hydrodynamics, the solution chemistry, and the pore space geometry. In this research we investigated the coupled influence of colloid concentration (over 4 orders of magnitude in 1 micron CML) and solution chemistry (pH=10, and ionic strength from 6 to 100 mM NaCl) on colloid transport and retention in packed (150 micron quartz sand) column experiments. Results demonstrated a strong coupling of colloid concentration and ionic strength (IS) on colloid retention. Specifically, the colloid retention percentage increased with IS and decreased with colloid concentration. The effect of concentration on colloid retention was very pronounced at an IS of 25 mM, but was relatively insignificant at an IS of 6 (unfavorable conditions) and 100 mM (favorable conditions). At an IS of 25 mM, hydrodynamic forces may funnel weakly associated colloids to the smallest regions of the pore space where they were retained. These weakly associated colloids are hypothesized to be susceptible to removal by colloid collisions that increase in frequency with increasing colloid concentration. In this way, increasing colloid concentrations would produce a lower mass flux to and retention in the smaller pore spaces.

Bradford, S. A.; Kim, H. N.; Haznedaroglu, B. Z.; Walker, S. L.; Torkzaban, S.

2008-12-01

388

Stacking-order dependence in thermoelectric transport of biased trilayer graphene  

NASA Astrophysics Data System (ADS)

We numerically study the thermoelectric and thermal transport in trilayer graphene with different stacking orders in the presence of interlayer bias under a strong perpendicular magnetic field. In the biased ABA-stacked case, we find that the thermoelectric conductivity displays different asymptotic behaviors with the varying of the temperature, similar to that of monolayer graphene. In the high-temperature regime, the transverse thermoelectric conductivity ?xy saturates to a universal value 2.77kBe/h at the center of each Landau level, while it displays a linear temperature dependence at the low-temperature limit. The calculated transverse thermal conductivity ?xy exhibits two plateaus away from the band center. The transition between the two plateaus is continuous, which is accompanied by a pronounced peak in the longitudinal thermal conductivity ?xx. In the biased ABC-stacked case, it is found that both the thermoelectric conductivity and thermal conductivity have similar properties to the biased bilayer graphene, which is consistent with the behavior of a band insulator. The obtained results demonstrate the sensitivity of the thermoelectric conductivity to the band gap near the Dirac point. We also verify the validity of the Mott relation and the generalized Wiedemann-Franz law.

Ma, R.; Sheng, L.; Liu, M.; Sheng, D. N.

2012-09-01

389

Fast strontium transport induced by hydrodynamic dispersion and pH-dependent sorption  

NASA Astrophysics Data System (ADS)

As a fluid carries solutes through a porous material, species that sorb onto the surface of the material travel more slowly than the fluid. Stronger adsorption results in slower solute migration, or increased solute retardation. The adsorption of strontium (Sr2+) onto iron-oxides is strongly pH-dependent and becomes significant at high pH. Radioactive Sr2+ isotopes are, therefore, commonly stored in alkaline solutions to maximize their retardation. Field observations and numerical simulations of the leakage of such solutions into low-pH soils, however, show that even Sr2+ stored in alkaline solutions can migrate without retardation. Migration occurs because hydrodynamic dispersion allows mixing of Sr2+ with the low-pH fluid forming an acidic Sr2+-rich plume which can travel without retardation. Here we report the first experimental observations confirming this dispersion-induced fast Sr2+ transport. We report column-flood experiments where a high-pH solution containing Sr2+ was injected into a low-pH porous medium of iron-oxide-coated beads. We observe both a strongly retarded Sr2+ front and an isolated fast pulse of Sr2+ traveling at the average fluid velocity. This dispersion-induced fast pulse of strontium must be taken into account when considering the safety of radionuclide storage in alkaline solutions.

Prigiobbe, Valentina; Hesse, Marc A.; Bryant, Steven L.

2012-09-01

390

Apical localization of sodium-dependent glucose transporter SGLT1 is maintained by cholesterol and microtubules.  

PubMed

A GFP-labeled sodium-dependent glucose transporter SGLT1 (SGLT-GFP) was transfected into MDCK cells. SGLT-GFP was localized at the apical membrane in confluent cells. When cellular cholesterol was depleted by methyl-beta-cyclodextrin (MbetaCD) treatment, the localization of SGLT-GFP gradually switched from apical to whole plasma membrane. Time-lapse microscopy revealed that the effect of MbetaCD appeared within 30 min, and that the transition of SGLT-GFP to the whole plasma membrane was completed within 2 hr after the administration. Immunofluorescence microscopy revealed that the tight junction framework remained steady during this process. The effect of MbetaCD on SGLT-GFP localization was counter-balanced by the addition of cholesterol into the culture medium. Disruption of microtubules by colcemid also perturbed SGLT-GFP localization. SGLT-GFP localized to the whole plasma membrane by colcemid treatment, and apical localization was restored within 1 hr after -removal of colcemid. Inhibition of protein synthesis by cycloheximide had no effect on the transition of SGLT-GFP induced by the MbetaCD or colcemid. These results indicated that the apical localization of SGLT-GFP is maintained by cellular cholesterol and microtubules, possibly with an apical recycling machinery. PMID:17327902

Suzuki, Takeshi; Matsuzaki, Toshiyuki; Hagiwara, Haruo; Aoki, Takeo; Tajika-Takahashi, Yukiko; Takata, Kuniaki

2006-12-06

391

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

PubMed

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

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

2012-11-14

392

Gene expression profiles of sodium-dependent vitamin C transporters in mice after alcohol consumption.  

PubMed

Alcoholic liver disease (ALD) is a serious liver problem in western countries. Our previous study has demonstrated that vitamin C plays a protective role in ALD. The vitamin C homeostasis is tightly regulated by sodium-dependent vitamin C transporters (SVCTs) 1 and 2. But the role of two SVCTs in ALD is less understood. In this study, we examined the expression patterns of two SVCTs in mice after alcohol consumption. Our results suggested that alcohol consumption obviously increased the expression of two SVCTs in liver and SVCT1 in kidney and intestine, which is important for vitamin C absorption. Vitamin C supplement increased the sera vitamin C content and ameliorated the symptom of ALD. Intestinal absorption and renal re-absorption mediated by SVCT1 are key factors to increase the sera vitamin C content after alcohol consumption. We proposed that both reactive oxygen species and low vitamin C concentration regulate the expression of SVCTs, and the protective role of vitamin C is mediated by suppressing the stability of hypoxia-inducible factor-1?. Thus, our study is significant for the understanding of vitamin C homeostasis in ALD and for better use of other antioxidants in ALD therapy. PMID:24080747

Guo, Xiaoqiang; Wang, Yuejia; Shen, Yongqing; Gao, Yingjie; Chang, Yanzhong; Duan, Xianglin

2013-09-29

393

Spatial and temporal features of density-dependent contaminant transport: experimental investigation and numerical modeling.  

PubMed

We investigate the spatial and temporal features of variable-density contaminant plumes migration in porous materials. Our analysis is supported by novel experimental results concerning concentration profiles inside a vertical column setup that has been conceived at CEA to this aim. The experimental method relies on X-ray spectrometry, which allows determining solute profiles as a function of time at several positions along the column. The salient outcomes of the measurements are elucidated, with focus on miscible fluids in homogeneous saturated media. The role of the injected solution molarity is evidenced. As molarity increases, the solutes plume transport progressively deviates from the usual Fickian behavior, and pollutants distribution becomes skewed in the direction dictated by gravity. By resorting to a finite elements approach, we numerically solve the nonlinear equations that rule the pollutants migration: a good agreement is found between the simulated profiles and the experimental data. At high molarity, a strong dependence on initial conditions is found. Finally, we qualitatively explore the (unstable) interfacial dynamics between the dense contaminant plume and the lighter resident fluid that saturates the column, and detail its evolution for finite-duration contaminant injections. PMID:19717206

Zoia, Andrea; Latrille, Christelle; Beccantini, Alberto; Cartadale, Alain

2009-07-28

394

TART 2000: A Coupled Neutron-Photon, 3-D, Combinatorial Geometry, Time Dependent, Monte Carlo Transport Code.  

National Technical Information Service (NTIS)

TART2000 is a coupled neutron-photon, 3 Dimensional, combinatorial geometry, time dependent Monte Carlo radiation transport code. This code can run on any modern computer. It is a complete system to assist you with input Preparation, running Monte Carlo c...

D. E. Cullen

2000-01-01

395

Ca(2+)-dependent heat production by rat skeletal muscle in hypertonic media depends on Na(+)-Cl- co-transport stimulation.  

PubMed Central

1. The rate of energy dissipation (E) in isolated, superfused soleus muscles from young rats was continuously measured under normosmotic and 100-mosM hyperosmotic conditions. The substantial increase of E with respect to basal level in hyperosmolarity (excess E), which is entirely dependent on the presence of extracellular sodium, was largely prevented or inhibited by bumetanide, a potent inhibitor of Na(+)-Cl- co-transport system, or by the removal of chloride from the superfusate (isethionate substitution). Bumetanide or the removal of chloride also acutely decreased basal E, by about 7%. 2. Bumetanide almost entirely suppressed the major, Ca(2+)-dependent part of excess E in hyperosmolarity, as well as the concomitant increase of 45Ca2+ efflux and small increase in resting muscle tension; in contrast, the part of excess E associated with stimulation of Na(+)-H+ exchange in hyperosmolarity was left unmodified. 3. Reduction of 22Na+ influx by bumetanide was more marked in hyperosmolarity than under control conditions, although stimulation of total 22Na+ influx by a 100-mosM stress was not statistically significant. Inhibition of Ca2+ release into the sarcoplasm using dantrolene sodium did not prevent the stimulation of bumetanide-sensitive 22Na+ influx, but rather increased it about fourfold. 4. It is concluded that the largest part of excess E in hyperosmolarity, which is Ca(2+)-dependent energy expenditure, is suppressed when steady-state stimulation of a Na(+)-Cl- co-transport system is inhibited either directly by bumetanide or the removal of extracellular chloride, or indirectly by the blocking of active Na(+)-K+ transport. How the stimulation of Na(+)-Cl- co-transport, by as little as 1 nmol s-1 (g wet muscle weight)-1 during a 100-mosM stress, enhances Ca(2+)-dependent heat by as much as 2.5 mW (g wet muscle weight)-1 remains to be clarified.

Chinet, A

1993-01-01

396

Azimuthal Decorrelation of Jets Widely Separated in Rapidity  

SciTech Connect

This study reports the first measurement of the azimuthal decorrelation between jets with pseudorapidity separation up to five units. The data were accumulated using the D0 detector during the 1992{endash}1993 collider run of the Fermilab Tevatron at {radical}{ital s}=1.8 TeV. These results are compared to next-to-leading order (NLO) QCD predictions and to two leading-log approximations (LLA) where the leading-log terms are resummed to all orders in {alpha}{sub {ital S}}. The final state jets as predicted by NLO QCD show less azimuthal decorrelation than the data. The parton showering LLA Monte Carlo HERWIG describes the data well; an analytical LLA prediction based on Balitsky-Fadin-Kuraev-Lipatov resummation shows more decorrelation than the data. {copyright} {ital 1996 The American Physical Society.}

Abachi, S.; Abbott, B.; Abolins, M.; Acharya, B.S.; Adam, I.; Adams, D.L.; Adams, M.; Ahn, S.; Aihara, H.; Alitti, J.; Alvarez, G.; Alves, G.A.; Amidi, E.; Amos, N.; Anderson, E.W.; Aronson, S.H.; Astur, R.; Avery, R.E.; Baarmand, M.M.; Baden, A.; Balamurali, V.; Balderston, J.; Baldin, B.; Banerjee, S.; Bantly, J.; Bartlett, J.F.; Bazizi, K.; Bendich, J.; Beri, S.B.; Bertram, I.; Bezzubov, V.A.; Bhat, P.C.; Bhatnagar, V.; Bhattacharjee, M.; Bischoff, A.; Biswas, N.; Blazey, G.; Blessing, S.; Bloom, P.; Boehnlein, A.; Bojko, N.I.; Borcherding, F.; Borders, J.; Boswell, C.; Brandt, A.; Brock, R.; Bross, A.; Buchholz, D.; Burtovoi, V.S.; Butler, J.M.; Carvalho, W.; Casey, D.; Castilla-Valdez, H.; Chakraborty, D.; Chang, S.; Chekulaev, S.V.; Chen, L.; Chen, W.; Choi, S.; Chopra, S.; Choudhary, B.C.; Christenson, J.H.; Chung, M.; Claes, D.; Clark, A.R.; Cobau, W.G.; Cochran, J.; Cooper, W.E.; Cretsinger, C.; Cullen-Vidal, D.; Cummings, M.A.; Cutts, D.; Dahl, O.I.; De, K.; Demarteau, M.; Denisenko, N.; Denisov, D.; Denisov, S.P.; Diehl, H.T.; Diesburg, M.; Di Loreto, G.; Dixon, R.; Draper, P.; Drinkard, J.; Ducros, Y.; Dugad, S.R.; Edmunds, D.; Ellison, J.; Elvira, V.D.; Engelmann, R.; Eno, S.; Eppley, G.; Ermolov, P.; Eroshin, O.V.; Evdokimov, V.N.; Fahey, S.; Fahland, T.; Fatyga, M.; Fatyga, M.K.; Featherly, J.; Feher, S.; Fein, D.; Ferbel, T.; Finocchiaro, G.; Fisk, H.E.; Fisyak, Y.; Flattum, E.; Forden, G.E.; Fortner, M.; Frame, K.C.; Franzini, P.; Fuess, S.; Gallas, E.; Galyaev, A.N.; Geld, T.; Genik, R.J. II; Genser, K.; Gerber, C.E.; Gibbard, B.; Glebov, V.; Glenn, S.; Glicenstein, J.F.; Gobbi, B.; Goforth, M.; Goldschmidt, A.; Gomez, B.; Gomez, G.; Goncharov, P.I.; Gonzalez Solis, J.L.; Gordon, H.; Goss, L.T.; Graf, N.; Grannis, P.D.; Green, D.R.; Green, J.; Greenlee, H.; Griffin, G.; Grossman, N.; Grudberg, P.; Gruenendahl, S.; Gu, W.X.; Guglielmo, G.; Guida, J.A.; Guida, J.M.; Guryn, W.; Gurzhiev, S.N.; Gutierrez, P.; Gutnikov, Y.E.; Hadley, N.J.

1996-07-01

397

Geometrical phase and surface plasmon focusing with azimuthal polarization.  

PubMed

Owing to a geometric phase effect, an isosceles triangular aperture etched into thin metal film leads to constructive or destructive interference of surface plasmons excited at the two equal sides under linearly polarized illumination. Through appropriate spatial arrangement of an array of triangles, a highly confined focal spot beyond the diffraction limit can be achieved at the geometric center under azimuthally polarized excitation with field enhancement comparable to a bull's eye plasmonic lens under radially polarized illumination. Through simply rotating the orientation of each triangle aperture by 90°, the plasmonic structure defocuses the same azimuthal polarization illumination due to destructive interference caused by a geometric ?-phase difference between the two sides of the triangle and between the adjacent triangles. PMID:22344113

Chen, Weibin; Nelson, Robert L; Zhan, Qiwen

2012-02-15

398

Temperature dependence of transport properties of spiro-MeOTAD as a hole transport material in solid-state dye-sensitized solar cells.  

PubMed

The internal transport and recombination parameters of solid-state dye-sensitized solar cells (ssDSCs) using the amorphous organic semiconductor 2,2',7,7'-tetrakis(N,N-di-p-methoxyphenylamine)-9,9'-spirobifluorene (spiro-MeOTAD) as a hole transport material (HTM) are investigated using electrical impedance spectroscopy. Devices were fabricated using flat and nanostructured TiO2 and compared to systems using nanostructured ZrO2 to differentiate between the transport processes within the different components of the ssDSC. The effect of chemically p-doping the HTM on its transport was investigated, and its temperature dependence was examined and analyzed using the Arrhenius equation. Using this approach the activation energy of the hole hopping transport within the undoped spiro-MeOTAD film was determined to be 0.34 ± 0.02 and 0.40 ± 0.02 eV for the mesoporous TiO2 and ZrO2 systems, respectively. PMID:23444960

Dualeh, Amalie; Moehl, Thomas; Nazeeruddin, Mohammad Khaja; Grätzel, Michael

2013-03-08

399

Azimuthal Asymmetries From Jets Quenched In Fluctuating Backgrounds  

NASA Astrophysics Data System (ADS)

High momentum jets and hadrons are important probes for the quark gluon plasma (QGP) formed in nuclear collisions at high energies. We investigate how fluctuations in the background density of the QGP and fluctuations in the spatial distribution of the hard process create azimuthal asymmetries of the high momentum hadron spectrum, described by the Fourier coefficients vn, n > 0 . We estimate the coefficients up to v6 in a simple energy loss model tuned to single inclusive hadron suppression.

Rodriguez, R.; Fries, R. J.

2013-09-01

400

3-D prestack migration of common-azimuth data  

Microsoft Academic Search

In principle, downward continuation of 3-D prestack data should be carried out in the 5-D space of full 3-D prestack geometry (recording time, source surface location, and receiver surface location), even when the data sets to be migrated have fewer dimensions, as in the case of common-azimuth data sets that are only four dimensional. This increase in dimensionality of the

Biondo Biondi; G. Palacharla

1996-01-01