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1

Azimuth Dependence of Solar Radiation on Inclined Surfaces II  

NASA Astrophysics Data System (ADS)

The author carried out an experiment to examine the azimuth dependences of solar radiation on an inclined suface. An integrating function recorder enabled measurements of solar radiation to be taken under all atmospheric conditions. The amount of solar radiation was determined to be greater on a westward-facing surface than on an eastward-facing surface throughout the year.

Shibata, Noboru

2000-02-01

2

Azimuth Dependence of Solar Radiation on Inclined Surfaces  

NASA Astrophysics Data System (ADS)

In general, the daily variation pattern of global solar radiation on an inclined surface is estimated by assuming the symmetrical daily variation of global solar radiation. The author carried out an experiment to examine the azimuth dependences of solar radiation on an inclined surface. In the experiment, the amount of solar radiation was found to be greater on a westward-facing surface than on an eastward-facing surface throughout the year.

Shibata, Noboru

1998-09-01

3

Azimuth Dependence of Solar Radiation on Inclined Surfaces III  

NASA Astrophysics Data System (ADS)

In general, the daily variation pattern of global solar radiation on an inclined surface is estimated by assuming the symmetrical daily variation of global solar radiation. The author carried out an experiment to examine the azimuth dependence of solar radiation on an inclined surface. In the experiment, the amount of solar radiation was found to be greater on a westward-facing surface than on an eastward-facing surface throughout the year.

Shibata, Noboru

2005-01-01

4

Randall-Sundrum graviton spin determination using azimuthal angular dependence  

E-print Network

Quantum interference of helicity amplitudes provides a powerful tool for measuring the spins of new particles. By looking at the azimuthal angular dependence of the differential cross-section in the production followed by decay of a new particle species one can determine its spin by looking at the various cosine modes. The heavy spin-2 Kaluza-Klein (KK) graviton provides a unique signature with a $\\cos{(4 \\phi)}$ mode. We study the feasibility of this approach to measuring the spin of the KK graviton in the Randall-Sundrum Model at the LHC.

Hitoshi Murayama; Vikram Rentala

2009-04-29

5

Numerical analysis of the azimuthal transport of solar particles  

NASA Astrophysics Data System (ADS)

An account is given of magnetic field structure details within the framework of analytical methods previously used by Perez-Peraza (1986) to describe global features of global azimuth transport phenomena involving particles generated in solar flares. A numerical solution is furnished for the model developed; particle energy spectra are derived at the level of the coronal magnetic field's roots for two specific proton events. Characteristics of the large-scale coronal magnetic field topology can be inferred by comparing these spectra with those derived from the interplanetary demodulation of solar proton data at the level of the earth.

Perez-Peraza, J.; Alvarez-Madrigal, M.; Rivero, F.

1987-05-01

6

Marine radar ocean wave retrieval's dependency on range and azimuth  

NASA Astrophysics Data System (ADS)

The strength of the surface wave signal in marine X-band radar (MR) images strongly depends on range and azimuth (i.e., the angle between antenna look and peak wave direction). Traditionally, MR wave analysis is carried out in a set of rectangular windows covering the radar field of view (FOV). The FOV is typically partially obstructed, e.g., due to the coastline or ship superstructures. Especially for ships that are subject to regular course changes, this results in an increased variability or error associated with wave parameters. Using MR measurements from R/P FLIP, acquired off California during the 2010 US Office of Naval Research (ONR) high resolution air-sea interaction (Hi-Res) experiment, this study quantifies the dependency of the radar-based 2D wave spectrum and parameters on range and azimuth. With the help of reference data from a nearby Datawell Waverider buoy, we propose empirical methods to remove the dependency and we illustrate their efficacy.

Lund, Björn; Collins, Clarence O.; Graber, Hans C.; Terrill, Eric; Herbers, Thomas H. C.

2014-07-01

7

Azimuthal angle dependence of dijet production in unpolarized hadron scattering  

SciTech Connect

We study the azimuthal angular dependence of back-to-back dijet production in unpolarized hadron scattering H{sub A}+H{sub B}{yields}J{sub 1}+J{sub 2}+X, arising from the product of two Boer-Mulders functions, which describe the transverse spin distribution of quarks inside an unpolarized hadron. We find that when the dijet is of two identical quarks (J{sub q}+J{sub q}) or a quark-antiquark pair (J{sub q}+J{sub q}), there is a cos{delta}{phi} angular dependence of the dijet, with {delta}{phi}={phi}{sub 1}-{phi}{sub 2}, and {phi}{sub 1} and {phi}{sub 2} are the azimuthal angles of the two individual jets. In the case of J{sub q}+J{sub q} production, we find that there is a color factor enhancement in the gluonic cross section, compared with the result from the standard generalized parton model. We estimate the cos{delta}{phi} asymmetry of dijet production at RHIC, showing that the color factor enhancement in the angular dependence of J{sub q}+J{sub q} production will reverse the sign of the asymmetry.

Lu Zhun; Schmidt, Ivan [Departamento de Fisica, Universidad Tecnica Federico Santa Maria, Casilla 110-V, Valparaiso (Chile) and Center of Subatomic Physics, Valparaiso (Chile)

2008-08-01

8

Charge-dependent azimuthal correlations from AuAu to UU collisions  

E-print Network

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

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

2013-11-21

9

Aspect dependence of the polarimetric characteristics of sea clutter: II. Variation with azimuth angle  

Microsoft Academic Search

The dependence of the spatial, temporal, Doppler and polarization characteristics of monostatic microwave radar sea clutter on the direction of observation relative to the prevailing sea direction has been the subject of many investigations. In most instances, though, the data and interpretation have focussed on the upwind\\/downwind and cross-wind directions, rather than exploring the detailed azimuthal variation. Such a policy

Stuart J. Anderson; James T. Morris

2008-01-01

10

Azimuthal angular dependence study of the atmospheric muon charge ratio at sea level using Geant4  

NASA Astrophysics Data System (ADS)

The azimuth dependence of the cosmic muon charge ratio at sea level was estimated using the Geant4 simulation package. Simulations were separately run at 12 azimuth angles ranging from 0° to 330° with 30° increment. Two hundred thousand proton and alpha particles were randomly distributed over the zenith angle range 30° < ? < 40° at each azimuth angle. The kinetic energy spectra of proton and helium nuclei were taken from the balloon-flight measurements. The atmospheric muon charge ratio was calculated at each azimuthal angle for low energy muons with a mean momentum around 0.5 GeV/c. The Geant4 simulation results have been compared with those of the CORSIKA simulation program and with the WILLI measurements. The simulation results reproduce well the measured east-west effect with a non-zero asymmetry AEW = 0.24. This asymmetry in the charge ratio decreases from 0.37 to 0.19 as the momentum increases from 0.22 to 0.70 GeV/c.

Arslan, Halil; Bektasoglu, Mehmet

2012-05-01

11

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

12

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

13

Azimuthal angle dependence of di-jet production in unpolarized hadron scattering  

SciTech Connect

We study the azimuthal asymmetry of back-to-back di-jet production in unpolarized hadron scattering, arising from the product of two Boer-Mulders functions, which describe the transverse spin distribution of quarks inside an unpolarized hadron. We find that there is a cos {delta}{phi} angular dependence of the di-jet, with {delta}{phi} the difference of the azimuthal angle of tow jets respectively. In the case of J{sub q}+J{sub q} production, we find that there is a color factor enhancement in the gluonic cross-section due to the multiple initial-/final-state interactions, compared with the result from the standard generalized parton model. We estimate the cos {delta}{phi} asymmetry of the total di-jet production at RHIC, showing that the color factor enhancement in the azimuthal asymmetric cross section of J{sub q}+J{sub q} production will reverse the sign of the asymmetry.

Lu Zhun; Schmidt, Ivan [Departamento de Fisica, Universidad Tecnica Federico Santa Maria, Valparaiso (Chile) and Center of Subatomic Physics, Valparaiso (Chile)

2009-08-04

14

Constraining Poiseuille flow in the asthenosphere using depth-dependence of azimuthal seismic anisotropy  

NASA Astrophysics Data System (ADS)

Asthenospheric flow accommodates differential shear between plate and mantle motions (Couette flow) and hosts additional flow driven by horizontal pressure gradients (Poiseuille flow) that may be associated with mantle upwelling and subduction. Determining the relative importance and spatial distribution of Poiseuille flow in the asthenosphere could help discriminate among competing theories of asthenospheric origin and shed light on thermal history of the Earth. Large uncertainties in the flow field and rheological structure of the upper mantle have thus far hindered our ability to constrain the relative importance of Couette and Poiseuille flows in the asthenosphere. We propose a new method to quantify Poiseuille flow in the asthenosphere using observations of the depth-dependence of azimuthal seismic anisotropy. In particular, we employ a simple one-dimensional Couette-Poiseuille flow model and analytically solve for the depth-profiles of the strain axis orientation in the asthenosphere, which approximates the orientation of azimuthal seismic anisotropy. We find that Couette-Poiseuille flow induces rotation of azimuthal seismic anisotropy with depth provided that the horizontal pressure gradient has a component transverse to plate motion. We then construct an algorithm that utilizes observed rotations of azimuthal seismic anisotropy with depth and analytical depth-profiles of the strain axis to invert for the horizontal pressure gradients everywhere in the asthenosphere. We test our method on the output of a global numerical mantle flow model. A comparison of our predicted pressure gradients with those computed directly from the numerical model shows a high degree of agreement, indicating that our method is robust. We show that our algorithm is stable, except for the case in which the component of the pressure gradient transverse to plate motion is close to zero. We establish that Poiseuille flow drives about 40% of the total flow velocity amplitude in the asthenosphere of the numerical model, which indicates that pressure gradients from mantle convection may be an important component of asthenospheric dynamics.

Natarov, Svetlana I.

15

Analytical method of characteristics applied to the azimuthally dependent solar wind  

NASA Astrophysics Data System (ADS)

The application of the analytical method of characteristics to the hypersonic part of a corotating quasi-steady configuration on the ecliptic plane of the azimuthally dependent solar wind is discussed. A QRH approximation has been improved at large heliocentric distances. The approximate equations are made exactly linear by a variable transformation to the characteristics coordinates. The initial value problem of the transformed equations is solved analytically by Riemann's method. Weak shock conditions are shown to be incorporated easily in our method of solution. A typical example is given which shows the appearance of a pair of weak shock waves in the flowfield.

Sakurai, T.

1983-06-01

16

Radial modal dependence of the azimuthal spectrum after parametric down-conversion  

NASA Astrophysics Data System (ADS)

The radial degrees of freedom of the biphoton states that are produced in spontaneous parametric down-conversion (SPDC) in the Laguerre-Gaussian (LG) basis are investigated, theoretically and experimentally. We calculated the theoretical azimuthal Schmidt numbers for different combinations of radial indices and found that a larger azimuthal Schmidt number is obtained for higher radial indices of the signal and idler beams. Moreover, larger azimuthal Schmidt numbers are also obtained when the difference between the two radial indices increases. Comparing these theoretical predictions with the azimuthal Schmidt numbers obtained from experimentally measurements, we found good agreement. Experimentally we demonstrated that it is possible to obtain a threefold increase in the azimuthal Schmidt number while maintaining a reasonable coincidence count rate by using LG modes with slightly larger radial indices.

Zhang, Yingwen; Roux, Filippus S.; McLaren, Melanie; Forbes, Andrew

2014-04-01

17

Magnetic-azimuth dependence of D-layer radio reflectivity, using lightning sferics as radio transmitters  

NASA Astrophysics Data System (ADS)

The Very Low Frequency (3-30 kHz) and Low-Frequency (30-300 kHz) radiation from lightning strokes provides a convenient intense source for studying radio propagation in the ionospheric D-region [Cheng and Cummer, 2005; Cheng et al., 2006; Cheng et al., 2007; Cummer et al., 1998; Jacobson et al., 2010; Shao and Jacobson, 2009]. In this poster we present a new study of the magnetic-azimuth dependence of D-layer radio reflectivity at relatively short ranges (r < 1000 km). This range regime is poorly adapted to a waveguide approach but is well treated by our discrete-reflection approach [Jacobson et al., 2009]. We use cloud-to-ground strokes, which are ~100X more numerous than the Narrow Bipolar Pulse sferics to which our method had previously been confined. Cheng, Z., and S. A. Cummer (2005), Broadband VLF measurements of lightning-induced ionospheric perturbations, Geophys. Res. Lett., 32, L08804, doi:08810.01029/02004GL022187. Cheng, Z., S. A. Cummer, D. N. Baker, and S. G. Kanekal (2006), Nighttime D region electron density profiles and variabilities inferred from broadband measurements using VLF radio emissions from lightning, J. Geophys. Res., 111, A05302, doi:05310.01029/02005JA011308. Cheng, Z., S. A. Cummer, H.-T. Su, and R.-R. Hsu (2007), Broadband very low frequency measurement of D region ionospheric perturbations caused by lightning electromagnetic pulses, J. Geophys. Res., 112, A06318. Cummer, S. A., U. S. Inan, and T. F. Bell (1998), Ionospheric D region remote sensing using VLF radio atmospherics, Radio Sci., 33, 1781-1792. Jacobson, A. R., X. Shao, and R. H. Holzworth (2009), Full-wave reflection of lightning long-wave radio pulses from the ionospheric D-region: Numerical model, J. Geophys. Res.- Space, 114, A03303, doi:03310.01029/02008JA013642. Jacobson, A. R., R. Holzworth, and X.-M. Shao (2010), Full-wave reflection of lightning long-wave radio pulses from the ionospheric D-region: Comparison with midday observations of broadband lightning signals, J. Geophys. Res. -Space, 115, A00E27, doi:10.1029/2009JA014540. Shao, X.-M., and A. R. Jacobson (2009), Model simulation of Very-Low-Frequency and Low-Frequency lightning signal propagation over intermediate ranges, IEEE Trans. Electromag. Compat., 51(3), 519-525.

Jacobson, A. R.; Shao, X.; Holzworth, R. H.; Lay, E. H.

2011-12-01

18

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

E-print Network

We present the measurements of particle pair yields per trigger particle obtained from di-hadron azimuthal correlations in pp collisions at $\\sqrt{s}$=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 Pythia6, Pythia8, and Phojet event generators.

Abelev, Betty; Adamova, Dagmar; Adare, Andrew Marshall; Aggarwal, Madan; Aglieri Rinella, Gianluca; Agnello, Michelangelo; Agocs, Andras Gabor; Agostinelli, Andrea; Ahammed, Zubayer; Ahmad, Arshad; Ahmad, Nazeer; Ahmed, Ijaz; Ahn, Sang Un; Ahn, Sul-Ah; Aimo, Ilaria; Ajaz, Muhammad; Akindinov, Alexander; Aleksandrov, Dmitry; Alessandro, Bruno; Alexandre, Didier; Alici, Andrea; Alkin, Anton; Alme, Johan; Alt, Torsten; Altini, Valerio; Altinpinar, Sedat; Altsybeev, Igor; Andrei, Cristian; Andronic, Anton; Anguelov, Venelin; Anielski, Jonas; Anson, Christopher Daniel; Anticic, Tome; Antinori, Federico; Antonioli, Pietro; Aphecetche, Laurent Bernard; Appelshauser, Harald; Arbor, Nicolas; Arcelli, Silvia; Arend, Andreas; Armesto, Nestor; Arnaldi, Roberta; Aronsson, Tomas Robert; Arsene, Ionut Cristian; Arslandok, Mesut; Asryan, Andzhey; Augustinus, Andre; Averbeck, Ralf Peter; Awes, Terry; Aysto, Juha Heikki; Azmi, Mohd Danish; Bach, Matthias Jakob; Badala, Angela; Baek, Yong Wook; Bailhache, Raphaelle Marie; Bala, Renu; Baldisseri, Alberto; Baltasar Dos Santos Pedrosa, Fernando; Ban, Jaroslav; Baral, Rama Chandra; Barbera, Roberto; Barile, Francesco; Barnafoldi, Gergely Gabor; Barnby, Lee Stuart; Barret, Valerie; Bartke, Jerzy Gustaw; Basile, Maurizio; Bastid, Nicole; Basu, Sumit; Bathen, Bastian; Batigne, Guillaume; Batyunya, Boris; Batzing, Paul Christoph; Baumann, Christoph Heinrich; Bearden, Ian Gardner; Beck, Hans; Behera, Nirbhay Kumar; Belikov, Iouri; Bellini, Francesca; Bellwied, Rene; Belmont-Moreno, Ernesto; Bencedi, Gyula; Beole, Stefania; Berceanu, Ionela; Bercuci, Alexandru; Berdnikov, Yaroslav; Berenyi, Daniel; Bergognon, Anais Annick Erica; Bertens, Redmer Alexander; Berzano, Dario; Betev, Latchezar; Bhasin, Anju; Bhati, Ashok Kumar; Bhom, Jihyun; Bianchi, Livio; Bianchi, Nicola; Bianchin, Chiara; Bielcik, Jaroslav; Bielcikova, Jana; Bilandzic, Ante; Bjelogrlic, Sandro; Blanco, F; Blanco, Francesco; Blau, Dmitry; Blume, Christoph; Boccioli, Marco; Bock, Friederike Bock; Boettger, Stefan; Bogdanov, Alexey; Boggild, Hans; Bogolyubsky, Mikhail; Boldizsar, Laszlo; Bombara, Marek; Book, Julian; Borel, Herve; Borissov, Alexander; Bornschein, Joerg; Bossu, Francesco; Botje, Michiel; Botta, Elena; Braidot, Ermes; Braun-Munzinger, Peter; Bregant, Marco; Breitner, Timo Gunther; Broker, Theo Alexander; Browning, Tyler Allen; Broz, Michal; Brun, Rene; Bruna, Elena; Bruno, Giuseppe Eugenio; Budnikov, Dmitry; Buesching, Henner; Bufalino, Stefania; Buncic, Predrag; Busch, Oliver; Buthelezi, Edith Zinhle; Caffarri, Davide; Cai, Xu; Caines, Helen Louise; Caliva, Alberto; Calvo Villar, Ernesto; Camerini, Paolo; Canoa Roman, Veronica; Cara Romeo, Giovanni; Carena, Francesco; Carena, Wisla; Carlin Filho, Nelson; Carminati, Federico; Casanova Diaz, Amaya Ofelia; Castillo Castellanos, Javier Ernesto; Castillo Hernandez, Juan Francisco; Casula, Ester Anna Rita; Catanescu, Vasile; Cavicchioli, Costanza; Ceballos Sanchez, Cesar; Cepila, Jan; Cerello, Piergiorgio; Chang, Beomsu; Chapeland, Sylvain; Charvet, Jean-Luc Fernand; Chattopadhyay, Subhasis; Chattopadhyay, Sukalyan; Cherney, Michael Gerard; Cheshkov, Cvetan; Cheynis, Brigitte; Chibante Barroso, Vasco Miguel; Chinellato, David; Chochula, Peter; Chojnacki, Marek; Choudhury, Subikash; Christakoglou, Panagiotis; Christensen, Christian Holm; Christiansen, Peter; Chujo, Tatsuya; Chung, Suh-Urk; Cicalo, Corrado; Cifarelli, Luisa; Cindolo, Federico; Cleymans, Jean Willy Andre; Colamaria, Fabio; Colella, Domenico; Collu, Alberto; Conesa Balbastre, Gustavo; Conesa del Valle, Zaida; Connors, Megan Elizabeth; Contin, Giacomo; Contreras, Jesus Guillermo; Cormier, Thomas Michael; Corrales Morales, Yasser; Cortese, Pietro; Cortes Maldonado, Ismael; Cosentino, Mauro Rogerio; Costa, Filippo; Cotallo, Manuel Enrique; Crescio, Elisabetta; Crochet, Philippe; Cruz Alaniz, Emilia; Cruz Albino, Rigoberto; Cuautle, Eleazar; Cunqueiro, Leticia; Czopowicz, Tobiasz Roman; Dainese, Andrea; Dang, Ruina; Danu, Andrea; Das, Indranil; Das, Supriya; Das, Debasish; Das, Kushal; Dash, Sadhana; Dash, Ajay Kumar; De, Sudipan; de Barros, Gabriel; De Caro, Annalisa; de Cataldo, Giacinto; de Cuveland, Jan; De Falco, Alessandro; De Gruttola, Daniele; Delagrange, Hugues; Deloff, Andrzej; De Marco, Nora; Denes, Ervin; De Pasquale, Salvatore; Deppman, Airton; D'Erasmo, Ginevra; de Rooij, Raoul Stefan; Diaz Corchero, Miguel Angel; Di Bari, Domenico; Dietel, Thomas; Di Giglio, Carmelo; Di Liberto, Sergio; Di Mauro, Antonio; Di Nezza, Pasquale; Divia, Roberto; Djuvsland, Oeystein

2013-01-01

19

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

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

20

Mixed harmonic charge dependent azimuthal correlations in Pb-Pb collisions at s=2.76TeV measured with the ALICE experiment at the LHC  

NASA Astrophysics Data System (ADS)

Mixed harmonic charge dependent azimuthal correlations at mid-rapidity in Pb-Pb collisions at s=2.76TeV were measured with the ALICE detector at the LHC. A clear charge dependence for a series of correlations is observed both via the multi-particle cumulant and the event plane methods. Implications from these measurements for the possible effects of the local parity violation in QCD and for models which incorporate the azimuthal anisotropic flow and the local charge conservation on the kinetic freeze-out surface are discussed.

Hori, Yasuto

2013-05-01

21

System Size Dependence of Azimuthal Correlations in Relativistic Heavy Ion Collisions  

E-print Network

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

Wolf G. Holzmann; for the PHENIX Collaboration

2006-08-16

22

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

23

Azimuth-dependent amplification of weak and strong ground motions within a fault zone (Nocera Umbra, central Italy)  

NASA Astrophysics Data System (ADS)

During three moderate-magnitude earthquakes occurred in September-October 1997 in the central Apennines, Italy, accelerations larger than 0.5 g were recorded in the town of Nocera Umbra, 10 to 15 km N-NW of the epicenters. The accelerograph is sited in a fault zone, close to a N30°E tectonic contact. Six temporary seismological stations installed across the fault recorded 82 aftershocks occurred in two seismogenic zones: the Colfiorito-Sellano area, S-SE of the array, and the Gualdo Tadino area, to the north. The array data reveal large variations in terms of both peak ground motions and spectral amplitudes. Within the fault zone, amplifications show a strong dependence on the source azimuth. At the accelerograph site, the effects are particularly large for events from S-SE: peak ground motions are a factor of 14 larger than those of a reference site and conventional spectral ratios attain amplitudes as large as 50 at 7 Hz along the N30°E direction of motion, parallel to the strike of the fault. Nineteen strong motion accelerograms were then used to compare ground motion properties between weak and strong events up to M0 = 1.2 × 1025 dyn cm. A particle motion analysis shows that the directional effect is also present in the strongest motions, even though the amplification of peak ground motion decreases when M0 increases. Results from stochastic simulations indicate that such a behavior is not due to nonlinearity: applying the empirical weak motion transfer functions in a purely linear model the observed peak ground motions of the largest events are fit satisfactorily.

Cultrera, Giovanna; Rovelli, Antonio; Mele, Giuliana; Azzara, Riccardo; Caserta, Arrigo; Marra, Fabrizio

2003-03-01

24

Dependence of enhanced asymmetry-induced transport on collision frequency  

NASA Astrophysics Data System (ADS)

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

Eggleston, D. L.

2014-07-01

25

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

Microsoft Academic Search

We present STAR measurements of the azimuthal anisotropy parameter vâ and the binary-collision scaled centrality ratio R{sub CP} for kaons and lambdas (Î + {bar Î}) at mid-rapidity in Au+Au collisions at âs{sub NN} = 200 GeV. In combination, the vâ and R{sub CP} particle-type dependencies contradict expectations from partonic energy loss followed by standard fragmentation in vacuum. We establish

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

2003-01-01

26

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

Microsoft Academic Search

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

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

2010-01-01

27

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

E-print Network

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 ...

Taylor, Frank E.

28

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

NASA Astrophysics Data System (ADS)

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

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

2010-05-01

29

Mixed harmonic charge dependent azimuthal correlations in Pb-Pb collisions at ?{sNN}=2.76 TeV measured with the ALICE experiment at the LHC  

NASA Astrophysics Data System (ADS)

Mixed harmonic charge dependent azimuthal correlations at mid-rapidity in Pb-Pb collisions at ?{sNN}=2.76 TeV were measured with the ALICE detector at the LHC. A clear charge dependence for a series of correlations is observed both via the multi-particle cumulant and the event plane methods. Implications from these measurements for the possible effects of the local parity violation in QCD and for models which incorporate the azimuthal anisotropic flow and the local charge conservation on the kinetic freeze-out surface are discussed.

Hori, Yasuto

2013-05-01

30

Gravity-dependent transport in industrial processes  

NASA Technical Reports Server (NTRS)

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

Ostrach, Simon; Kamotani, Yasuhiro

1994-01-01

31

Azimuthal Asymmetries and Collins Analyzing Power  

NASA Astrophysics Data System (ADS)

Spin azimuthal asymmetries in pion electro-production in deep inelastic scattering off longitudinally polarized protons, measured by HERMES, are well reproduced theoretically with no adjustable parameters. Predictions for azimuthal asymmetries for a longitudinally polarized deuteron target are given. The z-dependence of the Collins fragmentation function is extracted. The first information on e(x) is extracted from CLAS ALU asymmetry.

Efremov, A. V.; Goeke, K.; Schweitzer, P.

2002-11-01

32

Azimuthal dependence of classical over-barrier hopping diffusion of hydrogen on a vicinal Ni,,111... surface  

E-print Network

... surface E. Nabighian and X. D. Zhu* Department of Physics, University of California at Davis, One Shields, corrosion, and thermal annealing.1­4 Many experimental methods have been devised in the past decades a few lattice constants to microme- ters, depending upon substrates, the orientation of the top- most

Zhu, Xiangdong

33

BIOPHYSICS LETTER Transport at the nanoscale: temperature dependence  

E-print Network

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

Movileanu, Liviu

34

Collins Analyzing Power and Azimuthal Asymmetries  

NASA Astrophysics Data System (ADS)

Spin azimuthal asymmetries in pion electro-production in deep inelastic scattering off longitudinally polarized protons, measured by HERMES, are well reproduced theoretically with no adjustable parameters. Predictions for azimuthal asymmetries for a longitudinally polarized deuteron target are given. Using this the z-dependence of the Collins fragmentation function is extracted for the first time. The first information on e(x) is extracted from CLAS ALU asymmetry.

Efremov, A. V.; Goeke, K.; Schweitzer, P.

2003-07-01

35

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

SciTech Connect

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

Chatrchyan, Serguei; et al.

2012-05-01

36

Azimuthal decomposition with digital holograms.  

PubMed

We demonstrate a simple approach, using digital holograms, to perform a complete azimuthal decomposition of an optical field. Importantly, we use a set of basis functions that are not scale dependent so that unlike other methods, no knowledge of the initial field is required for the decomposition. We illustrate the power of the method by decomposing two examples: superpositions of Bessel beams and Hermite-Gaussian beams (off-axis vortex). From the measured decomposition we show reconstruction of the amplitude, phase and orbital angular momentum density of the field with a high degree of accuracy. PMID:22565722

Litvin, Igor A; Dudley, Angela; Roux, Filippus S; Forbes, Andrew

2012-05-01

37

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

E-print Network

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

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

2014-01-01

38

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

E-print Network

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

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

2014-01-29

39

Azimuthal-angle dependence of charged-pion-interferometry measurements with respect to second- and third-order event planes in Au+Au collisions at ?[S(NN)]=200??GeV.  

PubMed

Charged-pion-interferometry measurements were made with respect to the second- and third-order event plane for Au+Au collisions at sqrt[s_{NN}]=200??GeV. A strong azimuthal-angle dependence of the extracted Gaussian-source radii was observed with respect to both the second- and third-order event planes. The results for the second-order dependence indicate that the initial eccentricity is reduced during the medium evolution, which is consistent with previous results. In contrast, the results for the third-order dependence indicate that the initial triangular shape is significantly reduced and potentially reversed by the end of the medium evolution, and that the third-order oscillations are largely dominated by the dynamical effects from triangular flow. PMID:24949761

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

2014-06-01

40

On the efficiency of azimuthal and rotational splitting for Monte Carlo simulation of clinical linear accelerators  

Microsoft Academic Search

This article presents rotational splitting as a modification to the sampling process of the azimuthal angle used in the variance-reduction technique of azimuthal particle redistribution, with the goal to improve the efficiency of this variance-reduction technique for the Monte Carlo simulation of radiation transport in clinical linear accelerators. Using a constant azimuthal angle, instead of a random one, in the

L. Brualla; W. Sauerwein

2010-01-01

41

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

42

ATP-DEPENDENT SUGAR TRANSPORT COMPLEXITY IN HUMAN ERYTHROCYTES  

PubMed Central

Human erythrocyte glucose sugar transport was examined in resealed red cell ghosts under equilibrium exchange conditions ([sugar]intracellular = [sugar]extracellular). Exchange 3-O-methylglucose (3MG) import and export are monophasic in the absence of cytoplasmic ATP but are biphasic when ATP is present. Biphasic exchange is observed as the rapid filling of a large compartment (66% cell volume) followed by the slow filling of the remaining cytoplasmic space. Biphasic exchange at 20 mM 3MG eliminates the possibility that the rapid exchange phase represents ATP-dependent 3MG binding to the glucose transport protein (GLUT1; cellular [GLUT1] ? 20 ?M). Immunofluorescence activated cell sorting analysis shows that biphasic exchange does not result from heterogeneity in cell size or GLUT1 content. Nucleoside transporter mediated uridine exchange proceeds as rapidly as 3MG exchange but is monoexponential regardless of cytoplasmic [ATP]. This eliminates cellular heterogeneity or an ATP-dependent, nonspecific intracellular diffusion barrier as causes of biphasic exchange. Red cell ghost 3MG and uridine equilibrium volumes (130 fL) are unaffected by ATP. GLUT1 intrinsic activity is unchanged during rapid and slow phases of 3MG exchange. Two models for biphasic sugar transport are presented in which 3MG must overcome a sugar-specific, physical (diffusional) or chemical (isomerization) barrier to equilibrate with cell water. Partial transport inhibition using cytochalasin B or maltose depresses both rapid and slow phases of transport thereby eliminating the physical barrier hypothesis. We propose that biphasic 3MG transport results from ATP-dependent, differential transport of 3MG anomers in which Vmax/Km(app) for ?-3MG exchange transport is 19-fold greater than Vmax/Km(app) for ?-3MG transport. PMID:16928769

Leitch, Jeffry; Carruthers, Anthony

2014-01-01

43

Azimuthal Anisotropy of ?0 Production in Au+Au Collisions at sNN=200GeV: Path-Length Dependence of Jet Quenching and the Role of Initial Geometry  

NASA Astrophysics Data System (ADS)

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

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

2010-10-01

44

Transportation Center Seminar........ "Adaptive Routing in Stochastic Time-Dependent Networks  

E-print Network

), transportation planning under both normal and emergency conditions, and sustainable transportation systems. PriorTransportation Center Seminar........ "Adaptive Routing in Stochastic Time-Dependent Networks: Transportation Center, Chambers Hall Lower Level, 600 Foster St., Evanston Abstract Transportation systems

Bustamante, Fabián E.

45

TonB-dependent transporters and their occurrence in cyanobacteria  

PubMed Central

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

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

2009-01-01

46

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. PMID:22367204

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

2012-01-01

47

Time-dependent deterministic transport on parallel architectures using PARTISN  

Microsoft Academic Search

In addition to the ability to solve the static transport equation, the authors have also incorporated time dependence into the parallel S{sub N} code PARTISN. Using a semi-implicit scheme, PARTISN is capable of performing time-dependent calculations for both fissioning and pure source driven problems. They have applied this to various types of problems such as shielding and prompt fission experiments.

R. E. Alcouffe; R. S. Baker

1998-01-01

48

Time-Dependent Transport in Carbon Nanotube Transistors  

NASA Astrophysics Data System (ADS)

Recently, very high frequency properties of carbon nanotube field-effect transistors (FETs) are attracting extensive research interests due to their high mobility and near ballistic transport [1 -- 4]. To explore the performance limit of CNTFETs for very high frequency applications, it is important to understand time-dependent transport in CNTFETs. Self-consistent, quasi-static quantum simulations have been applied to assess the high-frequency performance [4]. However, the validity of quasi-static approximation needs to be examined. In addition, a full-time dependent simulation is necessary to examine some very important characteristics, such as frequency-dependent conductance. Our study on AC characteristics of CNTFETs is based on solving a full time-dependent quantum transport equation for CNTFETs using the finite difference time domain (FDTD) method for the first time. The dependence of small signal transconductance and gate capacitance on the frequency of the applied bias is examined. The intrinsic cut-off frequency, a device metric important for radio-frequency (RF) applications, and the intrinsic switching time, a metric important for digital switch applications, are computed using the full time-dependent simulations. The validity of the widely used quasi-static approximation is examined.

Chen, Yupeng; Guo, Jing; Wu, Thomas

2006-03-01

49

Transport and Anisotropic Diffusion in Time-Dependent Flow Visualization  

E-print Network

Transport and Anisotropic Diffusion in Time-Dependent Flow Visualization D. B¨urkle T. Preu�er by deformation to the velocity field in 2D or on surfaces in 3D. The Line Integral Convolution (LIC) approach to the visualization of flow fields. This method was based on the solution of an anisotropic diffusion prob- lem

Preusser, Tobias

50

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

2012-02-01

51

Azimuthal Frustration and Bundling in Columnar DNA Aggregates  

PubMed Central

The interaction between two stiff parallel DNA molecules is discussed using linear Debye-Hückel screening theory with and without inclusion of the dielectric discontinuity at the DNA surface, taking into account the helical symmetry of DNA. The pair potential furthermore includes the amount and distribution of counterions adsorbed on the DNA surface. The interaction does not only depend on the interaxial separation of two DNA molecules, but also on their azimuthal orientation. The optimal mutual azimuthal angle is a function of the DNA-DNA interaxial separation, which leads to azimuthal frustrations in an aggregate. On the basis of the pair potential, the positional and orientational order in columnar B-DNA assemblies in solution is investigated. Phase diagrams are calculated using lattice sums supplemented with the entropic contributions of the counterions in solution. A variety of positionally and azimuthally ordered phases and bundling transitions is predicted, which strongly depend on the counterion adsorption patterns. PMID:12770870

Harreis, H. M.; Likos, C. N.; Lowen, H.

2003-01-01

52

Temperature dependence of electronic transport property in ferroelectric polymer films  

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

53

Microfluidic-Enabled Liposomes Elucidate Size-Dependent Transdermal Transport  

PubMed Central

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

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

2014-01-01

54

Microfluidic-enabled liposomes elucidate size-dependent transdermal transport.  

PubMed

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

Hood, Renee R; Kendall, Eric L; Junqueira, Mariana; Vreeland, Wyatt N; Quezado, Zenaide; Finkel, Julia C; DeVoe, Don L

2014-01-01

55

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

56

On the energy-dependence of Hoechst 33342 transport by the ABC transporter LmrA  

Microsoft Academic Search

LmrA is an ATP-binding cassette (ABC) multidrug transporter from Lactococcus lactis, and is a structural homologue of the human multidrug resistance P-glycoprotein (ABCB1), the overexpression of which is associated with multidrug resistance in tumours. We recently observed that a truncated version of LmrA lacking the nucleotide-binding domain mediates a proton motive force-dependent ethidium transport reaction by catalyzing proton-ethidium symport. This

Henrietta Venter; Saroj Velamakanni; Lekshmy Balakrishnan; Hendrik W. van Veen

2008-01-01

57

Temperature dependent electrical transport of disordered reduced graphene oxide  

NASA Astrophysics Data System (ADS)

We report on the simple route for the synthesis of chemically reduced graphene oxide (rGO) using ascorbic acid (a green chemical) as a reducing agent. Temperature-dependent electrical transport properties of rGO thin films have been studied in a wide range (50 K T 400 K) of temperature. Electrical conduction in rGO thin films was displayed in two different temperature regimes. At higher temperatures, Arrhenius-like temperature dependence of resistance was observed indicating a band gap dominating transport behavior. At lower temperatures, the rGO sample showed a conduction mechanism consistent with Mott's two-dimensional variable range hopping (2D-VRH). An unsaturated negative magnetoresistance (MR) was observed up to 3 T field. A decrease in negative MR at high temperatures is attributed to the phonon scattering of charge carriers.

Muchharla, Baleeswaraiah; Narayanan, T. N.; Balakrishnan, Kaushik; Ajayan, Pulickel M.; Talapatra, Saikat

2014-06-01

58

Spin-dependent transport through Fe nanowires on Cu surfaces  

NASA Astrophysics Data System (ADS)

We investigate the transport properties of Fe nanowires on Cu (1 1 1) within the density functional theory. We calculate the electron band structure along the axis of the nanowires. On the basis of the numerical results, we find that some surface bands have one-dimensional dispersion along the nanowires and that some of them exist in the surface projected band gap. These results hint at the possibility of observing spin-dependent quantized current on this system.

Kishi, T.; Kasai, H.; Nakanishi, H.; Diño, W. A.; Komori, F.

2004-05-01

59

Engineering interband transport by time-dependent disorder  

NASA Astrophysics Data System (ADS)

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; Mannella, Riccardo; Wimberger, Sandro

2011-09-01

60

Time-dependent deterministic transport on parallel architectures using PARTISN  

SciTech Connect

In addition to the ability to solve the static transport equation, the authors have also incorporated time dependence into the parallel S{sub N} code PARTISN. Using a semi-implicit scheme, PARTISN is capable of performing time-dependent calculations for both fissioning and pure source driven problems. They have applied this to various types of problems such as shielding and prompt fission experiments. This paper describes the form of the time-dependent equations implemented, their solution strategies in PARTISN including iteration acceleration, and the strategies used for time-step control. Results are presented for a iron-water shielding calculation and a criticality excursion in a uranium solution configuration.

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

1998-07-01

61

Transport of hydrogen in metals with occupancy dependent trap energies  

NASA Astrophysics Data System (ADS)

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

Schmid, K.; von Toussaint, U.; Schwarz-Selinger, T.

2014-10-01

62

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

63

On the efficiency of azimuthal and rotational splitting for Monte Carlo simulation of clinical linear accelerators  

NASA Astrophysics Data System (ADS)

This article presents rotational splitting as a modification to the sampling process of the azimuthal angle used in the variance-reduction technique of azimuthal particle redistribution, with the goal to improve the efficiency of this variance-reduction technique for the Monte Carlo simulation of radiation transport in clinical linear accelerators. Using a constant azimuthal angle, instead of a random one, in the azimuthal particle redistribution technique, increases the efficiency of the simulation of a clinical linear accelerator by about 30% and reduces the latent variance of a 10×10 cm 2 phase space by about 40%.

Brualla, L.; Sauerwein, W.

2010-09-01

64

Time-dependent transport of electrons through a photon cavity  

NASA Astrophysics Data System (ADS)

We use a non-Markovian master equation to describe the transport of Coulomb-interacting electrons through an electromagnetic cavity with one quantized photon mode. The central system is a finite-parabolic quantum wire that is coupled weakly to external parabolic quasi-one-dimensional leads at t=0. With a stepwise introduction of complexity to the description of the system and a corresponding stepwise truncation of the ensuing many-body spaces, we are able to describe the time-dependent transport of Coulomb-interacting electrons through a geometrically complex central system. We take the full electromagnetic interaction of electrons and cavity photons without resorting to the rotating-wave approximation or reduction of the electron states to two levels into account. We observe that the number of initial cavity photons and their polarizations can have important effects on the transport properties of the system. The quasiparticles formed in the central system have lifetimes limited by the coupling to the leads and radiation processes active on a much longer time scale.

Gudmundsson, Vidar; Jonasson, Olafur; Tang, Chi-Shung; Goan, Hsi-Sheng; Manolescu, Andrei

2012-02-01

65

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

2011-10-01

66

Type IIc sodium-dependent phosphate transporter regulates calcium metabolism.  

PubMed

Primary renal inorganic phosphate (Pi) wasting leads to hypophosphatemia, which is associated with skeletal mineralization defects. In humans, mutations in the gene encoding the type IIc sodium-dependent phosphate transporter lead to hereditary hypophophatemic rickets with hypercalciuria, but whether Pi wasting directly causes the bone disorder is unknown. Here, we generated Npt2c-null mice to define the contribution of Npt2c to Pi homeostasis and to bone abnormalities. Homozygous mutants (Npt2c(-/-)) exhibited hypercalcemia, hypercalciuria, and elevated plasma 1,25-dihydroxyvitamin D(3) levels, but they did not develop hypophosphatemia, hyperphosphaturia, renal calcification, rickets, or osteomalacia. The increased levels of 1,25-dihydroxyvitamin D(3) in Npt2c(-/-) mice compared with age-matched Npt2c(+/+) mice may be the result of reduced catabolism, because we observed significantly reduced expression of renal 25-hydroxyvitamin D-24-hydroxylase mRNA but no change in 1alpha-hydroxylase mRNA levels. Enhanced intestinal absorption of calcium (Ca) contributed to the hypercalcemia and increased urinary Ca excretion. Furthermore, plasma levels of the phosphaturic protein fibroblast growth factor 23 were significantly decreased in Npt2c(-/-) mice. Sodium-dependent Pi co-transport at the renal brush border membrane, however, was not different among Npt2c(+/+), Npt2c(+/-), and Npt2c(-/-) mice. In summary, these data suggest that Npt2c maintains normal Ca metabolism, in part by modulating the vitamin D/fibroblast growth factor 23 axis. PMID:19056871

Segawa, Hiroko; Onitsuka, Akemi; Kuwahata, Masashi; Hanabusa, Etsuyo; Furutani, Junya; Kaneko, Ichiro; Tomoe, Yuka; Aranami, Fumito; Matsumoto, Natsuki; Ito, Mikiko; Matsumoto, Mitsuru; Li, Minqi; Amizuka, Norio; Miyamoto, Ken-Ichi

2009-01-01

67

Dimensional dependence of phonon transport in freestanding atomic layer systems  

NASA Astrophysics Data System (ADS)

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

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

2013-11-01

68

Spin-Dependent Transport Phenomena in Ferromagnet/Semiconductor Heterostructures  

NASA Astrophysics Data System (ADS)

This dissertation examines several aspects of spin-dependent transport phenomena in epitaxially grown ferromagnet/n-GaAs heterostructures. Further maturation of the field of semiconductor-based spintronics is hindered by difficulties in evaluating device performance across materials systems. Using Fe/n-GaAs and Co2MnSi/n-GaAs heterostructures as a test case, the main goal of this work is to demonstrate how such difficulties may be overcome by (1) specifying a more quantitative framework for evaluating transport parameters and (2) the introduction of a new spin-to-charge conversion phenomenon which may be parameterized by bulk semiconductor parameters. In the introductory chapter, this work is placed in the broader context of developing improved methods for the generation, modulation, and detection of spins. The lateral spin-valve geometry is presented as a concrete example of the typical measurement procedures employed. Chapter 2 presents the charge-based transport properties of these samples and establishes the notation and calculation techniques to be employed in subsequent chapters. In particular, we examine in detail the calculation of the electrochemical potential for a given carrier concentration. Chapter 3 provides a full derivation of the equations governing spin-dependent transport in the large polarization regime. This is applied to the case of extracting spin lifetimes and diffusion rates, demonstrating how quantitative agreement with theoretical predictions may be obtained upon properly accounting for both device geometry and material parameters. Further examination of the boundary conditions applicable to the heterojunctions of these samples demonstrates to what extent device performance may be parameterized across materials systems. Chapter 4 presents experimental observations of a new spin-to-charge conversion phenomenon using a non-magnetic probe. In the presence of a large non-equilibrium spin accumulation, the combination of a non-constant density of states and energy-dependent conductivity generates an electromotive force (EMF). It is shown that this signal dephases in the presence of applied and hyperfine fields, scales quadratically with the polarization, and is comparable in magnitude to the spin-splitting. Since this spin-generated EMF depends only on experimentally accessible parameters of the bulk material, its magnitude is used to quantify the injected spin polarization in absolute terms, independent of any assumptions regarding the spin-resistance of the interface. Chapter 5 examines spin-dependent contributions to signals measured in the Hall geometry. In particular, a large scattering asymmetry develops in the presence of hyperfine interactions with dynamically polarized nuclei. A pulsed measurement technique is introduced which allows the polarization of the electron spin system and nuclear spin system to be manipulated independently. Based on these results, a possible mechanism is presented based on inhomogeneities in the nuclear polarization. This motivates a phenomenological model which is compared against experimental data using the modeling techniques of the previous chapters.

Geppert, Chad Christopher

69

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. PMID:15548324

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

2004-01-01

70

Dimensional dependence of phonon transport in freestanding atomic layer systems.  

PubMed

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

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

2013-12-01

71

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

72

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

2013-05-01

73

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

74

Azimuthal variation of the P phase in Icelandic receiver functions  

NASA Astrophysics Data System (ADS)

A curious observation has been made on radial receiver functions calculated from teleseisms recorded by 29 broad-band seismometers distributed over Iceland. The arrival time of the direct P phase of the radial receiver functions depends critically upon the azimuth of the teleseismic source. For a seismic station in West Iceland, the direct P phase of the radial receiver function arrives consistently later for easterly source azimuths than for westerly source azimuths. The reverse applies for stations in East Iceland. In the original seismograms, the delayed P phase of the receiver function appears up to 450ms later on the radial than on the vertical component. The seismometer locations in East and West Iceland are separated by the Neovolcanic Zone, a constructive plate boundary. The delayed P phases occur for seismic rays travelling across this zone. However, it is not obvious how wave propagation across the plate boundary zone could cause the observed delays. The tentative explanation proposed here involves the regional dip of the Icelandic lava sequences towards the Neovolcanic Zone. A dipping interface at shallow depth results in a P-S converted phase arriving shortly after the P phase. These phases cannot be separated in the radial receiver functions, given the bandwidth of the observed signals. However, a calculation of receiver functions from estimates of the P, SV and SH wavefields clearly reveals a P-S converted phase at about 500ms for easterly source azimuths in West Iceland and for westerly source azimuths in East Iceland. The amplitudes of the direct P phase and the P-S phase converted at a dipping interface would be expected to vary strongly with azimuth in accordance with the observed behaviour.

Schlindwein, Vera

2001-01-01

75

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

Microsoft Academic Search

Developing a robust large-scale groundwater contaminate transport model requires quantifying the effect of heterogeneity and anisotropy on solute transport. Here we investigated the feasibility of using surface azimuthal resistivity methods to characterize near-surface anisotropy and heterogeneity in order to improve the conceptual model for uranium transport through unconsolidated sediment at the Integrated Field Research Challenge Site (IFRC) which borders the

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

2009-01-01

76

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

77

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

78

Radio-Transit Telescopes steerable in Azimuth  

Microsoft Academic Search

WHEN considering radio-transit telescopes, one ordinarily speaks in terms of instruments steerable in altitude. However, transit telescopes steered in azimuth have potentialities which should be evaluated. Bracewell1 and Drake2 have made suggestions for azimuth steerability. Both their designs utilize offset foci and the concept of a segmented reflecting surface.

P. D. Usher

1963-01-01

79

Evaluation of Fracture Azimuth by EM Wave and Elastic Wave  

NASA Astrophysics Data System (ADS)

Fracture system plays an important role in the development of underground energy, for example enhanced geothermal system (EGS), oil shale and shale gas, etc. Therefore, it becomes more and more important to detect and evaluate the fracture system. Geophysical prospecting is an useful method to evaluate the characteristics of the subsurface fractures. Currently, micro-seismology, multi-wave seismic exploration, and electromagnetic (EM) survey are reported to be used for the purpose. We are studying a method using both elastic wave and EM wave to detect and evaluate the fracture azimuth in laboratory. First, we build a 3D horizontal transverse isotropy (HTI) model, shown in the figure 1, by dry parallel fractures system, which was constructed by plexiglass plates and papers. Then, we used the ultrasonic system to obtain reflected S-wave data. Depending on the shear wave splitting, we evaluated the fracture azimuth by the algorithm of Pearson correlation coefficient. In addition, we used the full Polarimetric ultra wide band electromagnetic (FP-UWB-EM) wave System, shown in the figure 2, to obtain full polarimetric reflected EM-wave data. Depending on the rotation of the EM wave polarimetry, we evaluated the fracture azimuth by the the ration between maximum amplitude of co-polarimetric EM wave and maximum amplitude of cross-polarimetric EM wave. Finally, we used both EM-wave data and S-wave data to evaluate the fracture azimuth by the method of cross plot and statistical mathematics. To sum up, we found that FP-UWB-EM wave can be used to evaluated the fracture azimuth and is more accurate than ultrasound wave. Also joint evaluation using both data could improve the precision.

Feng, X.; Wang, Q.; Liu, C.; Lu, Q.; Zeng, Z.; Liang, W.; Yu, Y.; Ren, Q.

2013-12-01

80

An efficient time-domain approach for simulating Pe-dependent transport through fracture intersections  

E-print Network

Keywords: Discrete fracture network Solute transport Radionuclide Random walk a b s t r a c. Scalable models of flow and transport in discrete fracture networks that accurately represent the smallAn efficient time-domain approach for simulating Pe-dependent transport through fracture

Detwiler, Russell

81

Relative azimuth inversion by way of damped maximum correlation estimates  

NASA Astrophysics Data System (ADS)

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.

2012-06-01

82

Chaotic transport in time-dependent symplectic maps  

E-print Network

The effect of tune modulation in two-dimensional symplectic maps has been studied by using the concept of chaotic transport in terms of flux across resonances. When a single resonance is dominant, the particle escape due ...

Shi, Jack J

1996-05-20

83

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

84

Electron transport-dependent taxis in Rhodobacter sphaeroides.  

PubMed Central

Rhodobacter sphaeroides showed chemotaxis to the terminal electron acceptors oxygen and dimethyl sulfoxide, and the responses to these effectors were shown to be influenced by the relative activities of the different electron transport pathways. R. sphaeroides cells tethered by their flagella showed a step-down response to a decrease in the oxygen or dimethyl sulfoxide concentration when using them as terminal acceptors. Bacteria using photosynthetic electron transport, however, showed a step-down response to oxygen addition. Addition of the proton ionophore carbonyl cyanide 4-trifluoromethoxyphenylhydrazone did not cause a transient behavioral response, although it decreased the electrochemical proton gradient (delta p) and increased the rate of electron transport. However, removal of the ionophore, which caused an increase in delta p and a decrease in the electron transport rate, resulted in a step-down response. Together, these data suggest that behavioral responses of R. sphaeroides to electron transport effectors are caused by changes in the rate of electron transport rather than changes in delta p. PMID:7592334

Gauden, D E; Armitage, J P

1995-01-01

85

A Photon Transport Problem with a Time-Dependent Point Source  

E-print Network

A Photon Transport Problem with a Time-Dependent Point Source A Belleni-Morante Dipartimento di 2007 Abstract We consider a time-dependent problem of photon transport in an interstellar cloud with a point photon source modelled by a Dirac functional. The existence of a unique distributional solution

Mottram, Nigel

86

pH-Dependent passive and active transport of acidic drugs across Caco-2 cell monolayers  

Microsoft Academic Search

The aim of this study was to investigate pH-dependent passive and active transport of acidic drugs across Caco-2 cells. Therefore, the bidirectional pH-dependent transport of two acidic drugs, indomethacin and salicylic acid, across Caco-2 cells was studied in the physiological pH range of the gastrointestinal tract. The transport of both drugs decreased with increased pH, as expected from the pH-partition

Sibylle Neuhoff; Anna-Lena Ungell; Ismael Zamora; Per Artursson

2005-01-01

87

Measurement of azimuthal asymmetries in deep inelastic scattering  

Microsoft Academic Search

The distribution of the azimuthal angle for the charged hadrons has been studied in the hadronic centre-of-mass system for neutral current deep inelastic positron–proton scattering with the ZEUS detector at HERA. Measurements of the dependence of the moments of this distribution on the transverse momenta of the charged hadrons are presented. Asymmetries that can be unambiguously attributed to perturbative QCD

S. Bhadra; C. Catterall; J. E. Cole; W. R. Frisken; R. Hall-Wilton; M. Khakzad; S. Menary; J. Repond; R. Stanek; R. Yoshida; M. C. K. Mattingly; G. Abbiendi; F. Anselmo; P. Antonioli; G. Bari; M. Basile; L. Bellagamba; D. Boscherini; A. Bruni; G. Bruni; G. Cara Romeo; G. Castellini; L. Cifarelli; F. Cindolo; A. Contin; N. Coppola; M. Corradi; S. De Pasquale; P. Giusti; G. Iacobucci; G. Laurenti; G. Levi; A. Margotti; T. Massam; R. Nania; F. Palmonari; A. Pesci; A. Polini; G. Sartorelli; Y. Zamora Garcia; A. Zichichi; C. Amelung; A. Bornheim; I. Brock; K. Coböken; J. Crittenden; R. Deffner; H. Hartmann; K. Heinloth; E. Hilger; P. Irrgang; H.-P. Jakob; A. Kappes; U. F. Katz; R. Kerger; E. Paul; H. Schnurbusch; A. Stifutkin; J. Tandler; K. C. Voss; A. Weber; H. Wieber; D. S. Bailey; O. Barret; N. H. Brook; B. Foster; G. P. Heath; H. F. Heath; J. D. McFall; D. Piccioni; E. Rodrigues; J. Scott; R. J. Tapper; M. Capua; A. Mastroberardino; M. Schioppa; G. Susinno; H. Y. Jeoung; J. Y. Kim; J. H. Lee; I. T. Lim; K. J. Ma; M. Y. Pac; A. Caldwell; W. Liu; X. Liu; B. Mellado; S. Paganis; S. Sampson; W. B. Schmidke; F. Sciulli; J. Chwastowski; A. Eskreys; J. Figiel; K. Klimek; K. Olkiewicz; K. Piotrzkowski; M. Przybycien; P. Stopa; L. Zawiejski; B. Bednarek; K. Jelen; D. Kisielewska; A. M. Kowal; T. Kowalski; E. Rulikowska-Zarebska; L. Suszycki; D. Szuba; A. Kotanski; L. A. T. Bauerdick; U. Behrens; J. K. Bienlein; C. Burgard; D. Dannheim; K. Desler; G. Drews; A. Fox-Murphy; U. Fricke; F. Goebel; P. Göttlicher; R. Graciani; T. Haas; W. Hain; G. F. Hartner; D. Hasell; K. Hebbel; K. F. Johnson; M. Kasemann; W. Koch; U. Kötz; H. Kowalski; L. Lindemann; B. Löhr; M. Martínez; M. Milite; T. Monteiro; M. Moritz; D. Notz; F. Pelucchi; M. C. Petrucci; M. Rohde; P. R. B. Saull; A. A. Savin; U. Schneekloth; F. Selonke; M. Sievers; S. Stonjek; E. Tassi; G. Wolf; U. Wollmer; C. Youngman; W. Zeuner; C. Coldewey; A. Lopez-Duran Viani; A. Meyer; S. Schlenstedt; P. B. Straub; G. Barbagli; E. Gallo; P. Pelfer; G. Maccarrone; L. Votano; A. Bamberger; A. Benen; S. Eisenhardt; P. Markun; H. Raach; S. Wölfle; P. J. Bussey; A. T. Doyle; S. W. Lee; N. Macdonald; G. J. McCance; D. H. Saxon; L. E. Sinclair; I. O. Skillicorn; R. Waugh; I. Bohnet; N. Gendner; U. Holm; A. Meyer-Larsen; H. Salehi; K. Wick; A. Garfagnini; I. Gialas; L. K. Gladilin; D. Kçira; R. Klanner; E. Lohrmann; G. Poelz; F. Zetsche; R. Goncalo; K. R. Long; D. B. Miller; A. D. Tapper; R. Walker; U. Mallik; P. Cloth; D. Filges; T. Ishii; M. Kuze; K. Nagano; K. Tokushuku; S. Yamada; Y. Yamazaki; S. H. Ahn; S. B. Lee; S. K. Park; H. Lim; I. H. Park; D. Son; F. Barreiro; G. García; C. Glasman; O. Gonzalez; L. Labarga; J. del Peso; I. Redondo; J. Terrón; M. Barbi; F. Corriveau; D. S. Hanna; A. Ochs; S. Padhi; M. Riveline; D. G. Stairs; M. Wing; T. Tsurugai; V. Bashkirov; B. A. Dolgoshein; R. K. Dementiev; P. F. Ermolov; Y. A. Golubkov; I. I. Katkov; L. A. Khein; N. A. Korotkova; I. A. Korzhavina; V. A. Kuzmin; O. Y. Lukina; A. S. Proskuryakov; L. M. Shcheglova; A. N. Solomin; N. N. Vlasov; S. A. Zotkin; C. Bokel; M. Botje; N. Brümmer; J. Engelen; S. Grijpink; E. Koffeman; P. Kooijman; S. Schagen; A. van Sighem; H. Tiecke; N. Tuning; J. J. Velthuis; J. Vossebeld; L. Wiggers; E. de Wolf; D. Acosta; B. Bylsma; L. S. Durkin; J. Gilmore; C. M. Ginsburg; C. L. Kim; T. Y. Ling; S. Boogert; A. M. Cooper-Sarkar; R. C. E. Devenish; J. Große-Knetter; T. Matsushita; O. Ruske; M. R. Sutton; R. Walczak; A. Bertolin; R. Brugnera; R. Carlin; F. Dal Corso; U. Dosselli; S. Dusini; S. Limentani; M. Morandin; M. Posocco; L. Stanco; R. Stroili; C. Voci; L. Adamczyk; L. Iannotti; B. Y. Oh; J. R. Okrasinski; W. S. Toothacker; J. J. Whitmore; Y. Iga; G. D'Agostini; G. Marini; A. Nigro; C. Cormack; J. C. Hart; N. A. McCubbin; T. P. Shah; D. Epperson; C. Heusch; H. F.-W. Sadrozinski; A. Seiden; R. Wichmann; D. C. Williams; N. Pavel; H. Abramowicz; S. Dagan; S. Kananov; A. Kreisel; A. Levy; T. Abe; T. Fusayasu; K. Umemori; T. Yamashita; R. Hamatsu; T. Hirose; M. Inuzuka; S. Kitamura; T. Nishimura; M. Arneodo; N. Cartiglia; R. Cirio; M. Costa; M. I. Ferrero; S. Maselli; V. Monaco; C. Peroni; M. Ruspa; R. Sacchi; A. Solano; A. Staiano; M. Dardo; D. C. Bailey; C.-P. Fagerstroem; R. Galea; T. Koop; G. M. Levman; J. F. Martin; R. S. Orr; S. Polenz; A. Sabetfakhri; D. Simmons; J. M. Butterworth; M. E. Hayes; E. A. Heaphy; T. W. Jones; B. J. West; J. Ciborowski; R. Ciesielski; G. Grzelak; R. J. Nowak; J. M. Pawlak; R. Pawlak; B. Smalska; T. Tymieniecka; A. K. Wróblewski; J. A. Zakrzewski; A. F. arnecki; M. Adamus; T. Gadaj; O. Deppe; Y. Eisenberg; D. Hochman; U. Karshon; W. F. Badgett; D. Chapin; R. Cross; C. Foudas; S. Mattingly; D. D. Reeder; W. H. Smith; A. Vaiciulis; T. Wildschek; M. Wodarczyk; A. Deshpande; S. Dhawan; V. W. Hughes

2000-01-01

88

Parameter Dependence of Drift Mode Transport Model for Tokamaks  

NASA Astrophysics Data System (ADS)

A quasi-linear model for transport driven by drift modes is an essential element of the Multi-Mode core transport model. A new version of the quasi-linear drift mode model now includes the following features: The plasma can consist of an arbitrary number of ion species; the transport is integrated over a spectrum of perpendicular wavelengths; eigenfunctions are extended along magnetic field lines, which is particularly important in high beta plasmas with low magnetic shear; and the effects of particle collisions are included. The growth rates of the modes as well as thermal and particle transport are explored in plasmas consisting of multiple hydrogenic and impurity ion species. The model is tested in a stand-alone code by varying plasma parameters such as the temperature gradients, density gradients, plasma beta, magnetic shear, temperature ratios, plasma elongation and collisionality. The results stored in an MDSplus tree and analyzed using IDL. Supported by NSF grant PHY 9820301 and DOE grant DOE DE-FG02-92-ER-54141.

Lindsey, M.; Bateman, G.; Kritz, A. H.; Strand, P.; Weiland, J.

2003-10-01

89

Parametric Dependencies of Transport Using Gyrokinetic Simulations Including Kinetic Electrons  

NASA Astrophysics Data System (ADS)

Nonlinear gyrokinetic simulations are used to systematically study the effects of ExB shear, magnetic shear, safety factor q, Ti/Te, collisionality, plasma beta, and shaping on turbulent energy, particle, and momentum transport due to ion temperature gradient (ITG) and trapped electron modes (TEM) using the GYRO code [1]. Previous work has tended to focus on ITG modes with adiabatic electrons for a single reference case. Here, we report on over 300 nonlinear kinetic electron simulations to be used for benchmarking and transport model development. In simulations varying q, the energy transport exhibits a linear q-scaling while the particle diffusivity can be insensitive to q. For shifted circle geometry, the effect of ExB shear on both ITG and TEM transport is well modeled by a simple quench rule. The quench rule needs to be modified, however, for real geometry. The nonlinear results are compared against quasilinear (QL) diffusivity ratios to assess the accuracy of QL theory on a per-mode basis.In collaboration with R.E. Waltz and J. Candy, General Atomics. [1] J. Candy and R.E. Waltz, Phys. Rev. Lett. 91, 045001 (2003).

Kinsey, J. E.

2006-04-01

90

The SLC34 family of sodium-dependent phosphate transporters.  

PubMed

The SLC34 family of sodium-driven phosphate cotransporters comprises three members: NaPi-IIa (SLC34A1), NaPi-IIb (SLC34A2), and NaPi-IIc (SLC34A3). These transporters mediate the translocation of divalent inorganic phosphate (HPO4 (2-)) together with two (NaPi-IIc) or three sodium ions (NaPi-IIa and NaPi-IIb), respectively. Consequently, phosphate transport by NaPi-IIa and NaPi-IIb is electrogenic. NaPi-IIa and NaPi-IIc are predominantly expressed in the brush border membrane of the proximal tubule, whereas NaPi-IIb is found in many more organs including the small intestine, lung, liver, and testis. The abundance and activity of these transporters are mostly regulated by changes in their expression at the cell surface and are determined by interactions with proteins involved in scaffolding, trafficking, or intracellular signaling. All three transporters are highly regulated by factors including dietary phosphate status, hormones like parathyroid hormone, 1,25-OH2 vitamin D3 or FGF23, electrolyte, and acid-base status. The physiological relevance of the three members of the SLC34 family is underlined by rare Mendelian disorders causing phosphaturia, hypophosphatemia, or ectopic organ calcifications. PMID:24352629

Wagner, Carsten A; Hernando, Nati; Forster, Ian C; Biber, Jürg

2014-01-01

91

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

92

Temperature dependence of amino acid transport in brain slices  

Microsoft Academic Search

A decrease in amino acid influx and exit in incubated slices when the temperature was lowered from 37 to 20°C was observed with all 16 amino acids examined at two concentrations (1 mM and 10 µM). The temperature dependence of cellular amino acid influx observed in slices in vitro contrasts with the absence of temperature dependence of capillary amino acid

M. Banay-Schwartz; K. Lajtha; H. Sershen; A. Lajtha

1977-01-01

93

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

94

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

95

Specificity of the Na + -dependent monocarboxylic acid transport pathway in rabbit renal brush border membranes  

Microsoft Academic Search

Summary The substrate specificity of a Na+-dependent transport pathway forl-lactate was studied in rabbit renal brush border membrane vesicles.Jmax forl-lactate transport was unaffected by the presence of a fixed concentration of two different short-chain monocarboxylic acids, while the apparentKt(Ka) forl-lactate increased, and this is compatible with competitive inhibition. The inhibitor constants (“Ki”'s) for the transport pathway for the two solutes

Edward P. Nord; Stephen H. Wright; Ian Kippen; Ernest M. Wright

1983-01-01

96

Oxygen-dependent electron transport and protection from photoinhibition in leaves of tropical tree species  

Microsoft Academic Search

The roles of photorespiration and the Mehlerperoxidase pathway in sustaining electron transport and protection from photoinhibition were studied in outer canopy leaves of two species of tropical trees: the drought-deciduous Pseudobombax septenatum (Jacq.) Dug. and the evergreen Ficus insipida Willd. Ficus had a higher photosynthetic capacity than Pseudobombax and also a greater capacity for light-dependent electron transport under photorespiratory conditions

Catherine E. Lovelock; Klaus Winter

1996-01-01

97

Photon transport in a time-dependent 3D region Aldo Belleni-Morante1  

E-print Network

Photon transport in a time-dependent 3D region Aldo Belleni-Morante1 , Roberto Monaco2 , Sandra roberto.monaco@polito.it, sandra.pieraccini@polito.it Abstract Photon transport is studied that the time behaviour of V (t) is unknown and the photon distribution function is measured at a location far

Ceragioli, Francesca

98

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

E-print Network

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

Ramsak, Anton

99

Length-Dependent Thermal Transport along Molecular Chains  

NASA Astrophysics Data System (ADS)

We present heat-transport measurements conducted with a vacuum-operated scanning thermal microscope to study the thermal conductance of monolayers of nine different alkane thiols self-assembled on Au(111) surfaces as a function of their length (2 to 18 methylene units). The molecular thermal conductance is probed in a confined area with a diameter below 10 nm in the contact between a silicon tip and the self-assembled monolayer. This yields a pWK-1 sensitivity per molecule at a tip temperature of 200-300 °C versus the gold at room temperature. We found a conductance variance of up to a factor of 3 as a function of alkane chain length, with maximum conductance for a chain length of four carbon atoms.

Meier, T.; Menges, F.; Nirmalraj, P.; Hölscher, H.; Riel, H.; Gotsmann, B.

2014-08-01

100

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

101

Na+-dependent transport of taurine by membrane vesicles of neuroblastoma x glioma hybrid cells.  

PubMed

The transport of taurine into membrane vesicles prepared from neuroblastoma x glioma hybrid cells 108CC5 was studied. A great part of the taurine uptake by the membrane preparation is due to the transport into an osmotically sensitive space of membrane vesicles. Taurine uptake by membrane vesicles is an active transport driven by the concentration gradient of Na+ across the membrane (outside concentration greater than inside). The Km value of 36 microM for Na+-dependent taurine uptake indicates a high-affinity transport system. The rate of taurine transport by the membrane vesicles is enhanced by the K+ gradient (inside concentration greater than outside) and the K+ ionophore valinomycin. Taurine transport is inhibited by several structural analogs of taurine: hypotaurine, beta-alanine, and taurocyamine. All these results indicate that the taurine transport system of the membrane vesicles displays properties almost identical to those of intact neuroblastoma X glioma hybrid cells. PMID:3598583

Yuasa, S; Hamprecht, B

1987-08-01

102

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

NASA Astrophysics Data System (ADS)

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

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

2009-12-01

103

Deterministic methods for time-dependent stochastic neutron transport  

SciTech Connect

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

Baker, Randal S [Los Alamos National Laboratory

2009-01-01

104

Structural insights into substrate recognition in proton-dependent oligopeptide transporters  

PubMed Central

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

Guettou, Fatma; Quistgaard, Esben M; Tresaugues, Lionel; Moberg, Per; Jegerschold, Caroline; Zhu, Lin; Jong, Agnes Jin Oi; Nordlund, Par; Low, Christian

2013-01-01

105

Relationship between the IMF azimuthal angle and solar wind velocity  

NASA Astrophysics Data System (ADS)

The relationship between the IMF azimuthal angle and plasma velocity has been studied independently for three types of solar wind streams (recurrent and transient high-speed streams and low-speed background wind) based on the interplanetary medium parameters measured in the near-Earth orbits in 1964-1996. The relationships between the IMF azimuthal angle cotangent and plasma velocity are close to linear but strongly differ from one another and from the theoretical relationship for all types of streams. These differences area caused by the magnetic field disturbance on the time scales smaller than a day, and the effect of this disturbance has been studied quantitatively. The effective periods of rotation of the IMF sources on the Sun, depending on the solar cycle phase, have been obtained from the relations between the IMF azimuthal angle cotangent and plasma velocity. During the most part of the solar cycle, the periods of rotation of the IMF sources are close to the period of rotation of the solar equator but abruptly increase to the values typical of the solar circumpolar zones in the years of solar minimums.

Erofeev, D. V.

2008-04-01

106

Hole mobility enhancement in uniaxial stressed Ge dependence on stress and transport direction  

NASA Astrophysics Data System (ADS)

Utilizing a six-band k.p valence band calculations that considered a strained perturbation Hamiltonian, uniaxial stress-induced valence band structure parameters for Ge such as band edge energy shift, split, and effective mass were quantitatively evaluated. Based on these valence band parameters, the dependence of hole mobility on uniaxial stress (direction, type, and magnitude) and hole transport direction was theoretical studied. The results show that the hole mobility had a strong dependence on the transport direction and uniaxial stress. The hole mobility enhancement can be found for all transport directions and uniaxial stess configurations, and the hole transport along the [110] direction under the uniaxial [110] compressive stress had the highest mobility compared to other transport directions and stress configurations.

Ma, JianLi; Fu, ZhiFen; Liu, Peng; Zhang, HeMing

2014-10-01

107

A molecular mechanism for aberrantCFTR-dependent HCO3– transport in cystic fibrosis  

PubMed Central

Aberrant HCO3– transport is a hallmark of cystic fibrosis (CF) and is associated with aberrant Cl–-dependent HCO3– transport by the cystic fibrosis transmembrane conductance regulator (CFTR). We show here that HCO3– current by CFTR cannot account for CFTR-activated HCO3– transport and that CFTR does not activate AE1–AE4. In contrast, CFTR markedly activates Cl– and OH–/HCO3– transport by members of the SLC26 family DRA, SLC26A6 and pendrin. Most notably, the SLC26s are electrogenic transporters with isoform-specific stoichiometries. DRA activity occurred at a Cl–/HCO3– ratio ?2. SLC26A6 activity is voltage regulated and occurred at HCO3–/Cl– ?2. The physiological significance of these findings is demonstrated by interaction of CFTR and DRA in the mouse pancreas and an altered activation of DRA by the R117H and G551D mutants of CFTR. These findings provide a molecular mechanism for epithelial HCO3– transport (one SLC26 transporter—electrogenic transport; two SLC26 transporters with opposite stoichiometry in the same membrane domain—electroneutral transport), the CF-associated aberrant HCO3– transport, and reveal a new function of CFTR with clinical implications for CF and congenital chloride diarrhea. PMID:12411484

Ko, Shigeru B.H.; Shcheynikov, Nikolay; Choi, Joo Young; Luo, Xiang; Ishibashi, Kenichi; Thomas, Philip J.; Kim, Joo Young; Kim, Kyung Hwan; Lee, Min Goo; Naruse, Satoru; Muallem, Shmuel

2002-01-01

108

ATP-dependent transport of unconjugated bilirubin by rat liver canalicular plasma membrane vesicles.  

PubMed

The transport of highly purified 3H-labelled unconjugated bilirubin (UCB) was investigated in rat liver plasma membrane vesicles enriched in the canalicular domain and found to be stimulated (more than 5-fold) by the addition of ATP. Other nucleotides, such as AMP, ADP, GTP and a non-hydrolysable ATP analogue (adenosine 5'-[alpha, beta-methylene] triphosphate), did not stimulate [3H]UCB transport, indicating that ATP hydrolysis was necessary for the stimulatory effect. [3H]UCB uptake occurred into an osmotically sensitive space. At an unbound bilirubin concentration ([Bf]) below saturation of the aqueous phase (no more than 70 nM UCB), the ATP-dependent transport followed saturation kinetics with respect to [Bf], with a Km of 26+/-8 nM and a Vmax of 117+/-11 pmol per 15 s per mg of protein. Unlabelled UCB inhibited the uptake of [3H]UCB, indicating that UCB was the transported species. Inhibitors of ATPase activity such as vanadate or diethyl pyrocarbonate decreased the ATP effect (59+/-11% and 100% respectively). Daunomycin, a known substrate for multidrug resistance protein-1, and taurocholate did not inhibit the ATP-dependent [3H]UCB transport, suggesting that neither mdr-1 nor the canalicular bile acid transporter is involved in the canalicular transport of UCB. [3H]UCB uptake (both with and without ATP) in canalicular vesicles obtained from TR- rats was comparable to that in vesicles obtained from Wistar rats, indicating that the canalicular multispecific organic anion transporter, cMOAT, does not account for UCB transport. These results indicate that UCB is transported across the canalicular membrane of the liver cell by an ATP-dependent mechanism involving an as yet unidentified transporter. PMID:9512466

Pascolo, L; Bayon, E J; Cupelli, F; Ostrow, J D; Tiribelli, C

1998-04-01

109

ATP-dependent transport of unconjugated bilirubin by rat liver canalicular plasma membrane vesicles.  

PubMed Central

The transport of highly purified 3H-labelled unconjugated bilirubin (UCB) was investigated in rat liver plasma membrane vesicles enriched in the canalicular domain and found to be stimulated (more than 5-fold) by the addition of ATP. Other nucleotides, such as AMP, ADP, GTP and a non-hydrolysable ATP analogue (adenosine 5'-[alpha, beta-methylene] triphosphate), did not stimulate [3H]UCB transport, indicating that ATP hydrolysis was necessary for the stimulatory effect. [3H]UCB uptake occurred into an osmotically sensitive space. At an unbound bilirubin concentration ([Bf]) below saturation of the aqueous phase (no more than 70 nM UCB), the ATP-dependent transport followed saturation kinetics with respect to [Bf], with a Km of 26+/-8 nM and a Vmax of 117+/-11 pmol per 15 s per mg of protein. Unlabelled UCB inhibited the uptake of [3H]UCB, indicating that UCB was the transported species. Inhibitors of ATPase activity such as vanadate or diethyl pyrocarbonate decreased the ATP effect (59+/-11% and 100% respectively). Daunomycin, a known substrate for multidrug resistance protein-1, and taurocholate did not inhibit the ATP-dependent [3H]UCB transport, suggesting that neither mdr-1 nor the canalicular bile acid transporter is involved in the canalicular transport of UCB. [3H]UCB uptake (both with and without ATP) in canalicular vesicles obtained from TR- rats was comparable to that in vesicles obtained from Wistar rats, indicating that the canalicular multispecific organic anion transporter, cMOAT, does not account for UCB transport. These results indicate that UCB is transported across the canalicular membrane of the liver cell by an ATP-dependent mechanism involving an as yet unidentified transporter. PMID:9512466

Pascolo, L; Bayon, E J; Cupelli, F; Ostrow, J D; Tiribelli, C

1998-01-01

110

Proline transport in Leishmania donovani amastigotes: dependence on pH gradients and membrane potential.  

PubMed

Amastigotes of Leishmania donovani develop and multiply within the acidic phagolysosomes of mammalian macrophages. Isolated amastigotes are acidophilic; they catabolize substrates and synthesize macromolecules optimally at pH 5.5. Substrate transport in amastigotes has not been characterized. Here we show that amastigotes exhibit an uphill transport of proline (active transport) with an acid pH optimum (pH 5.5). It is dependent upon metabolic energy and is driven by proton motive force. Agents which selectively disturb the component forces of proton motive force, such as carbonyl cyanide chlorophenylhydrazone, nigericin and valinomycin, inhibit proline transport. Transport is sensitive to dicyclohexylcarbodiimide and insensitive to ouabain, demonstrating the involvement of a proton ATPase in the maintenance of proton motive force. It is suggested that the plasma membrane pH gradient probably makes the greatest contribution to proton motive force that drives substrate transport in the amastigote stage. PMID:1533014

Glaser, T A; Mukkada, A J

1992-03-01

111

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. PMID:22641192

Razak, K.A.

2012-01-01

112

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

113

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

E-print Network

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.

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

2012-03-13

114

The PTS(Ntr) system globally regulates ATP-dependent transporters in Rhizobium leguminosarum.  

PubMed

Mutation of ptsP encoding EI(Ntr) of the PTS(Ntr) system in Rhizobium leguminosarum strain Rlv3841 caused a pleiotropic phenotype as observed with many bacteria. The mutant formed dry colonies and grew poorly on organic nitrogen or dicarboxylates. Most strikingly the ptsP mutant had low activity of a broad range of ATP-dependent ABC transporters. This lack of activation, which occurred post-translationally, may explain many of the pleiotropic effects. In contrast proton-coupled transport systems were not inhibited in a ptsP mutant. Regulation by PtsP also involves two copies of ptsN that code for EIIA(Ntr) , resulting in a phosphorylation cascade. As in Escherichia coli, the Rlv3841 PTS(Ntr) system also regulates K(+) homeostasis by transcriptional activation of the high-affinity ATP-dependent K(+) transporter KdpABC. This involves direct interaction of a two-component sensor regulator pair KdpDE with unphosphorylated EIIA(Ntr) . Critically, ptsP mutants, which cannot phosphorylate PtsN1 or PtsN2, had a fully activated KdpABC transporter. This is the opposite pattern from that observed with ABC transporters which apparently require phosphorylation of PtsN. These results suggest that ATP-dependent transport might be regulated via PTS(Ntr) responding to the cellular energy charge. ABC transport may be inactivated at low energy charge, conserving ATP for essential processes including K(+) homeostasis. PMID:22340847

Prell, J; Mulley, G; Haufe, F; White, J P; Williams, A; Karunakaran, R; Downie, J A; Poole, P S

2012-04-01

115

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

116

Azimuthal decorrelations of dijets in QCD  

E-print Network

We report on the status of the QCD analysis of dijet azimuthal decorrelations. We emphasise the relevance of resummation of soft and collinear enhancements in describing these observables in the region where the two jets are nearly back-to-back in the transverse plane. We also discuss the sources of theoretical uncertainties and possible research directions aimed at their reduction.

Andrea Banfi

2009-06-26

117

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

E-print Network

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

Chabreyrie, Rodolphe

2014-01-01

118

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

119

Azimuthal temperature modulations of Saturn's A ring caused by self-gravity wakes  

NASA Astrophysics Data System (ADS)

The physical temperatures of the Saturn's A ring measured by the Cassini Composite Infrared Spectrometer (CIRS) show quadrupole azimuthal modulations besides temperature drops in Saturn's shadow. These azimuthal modulations are likely to be caused by self-gravity wakes. In this paper, we develop a new thermal model in which wakes are modeled as elliptical cylinders ignoring inter-wake particles. All the heat fluxes are calculated explicitly taking into account inter-wake shadowing and heating. We apply our model to azimuthal scans of the A ring obtained by CIRS. It is found that the azimuthal modulation of the ring temperature is primarily caused by the azimuthal variation of the geometric filling factor of the ring seen from the Sun. The thermal inertia estimated from the eclipse data (data only inside and near Saturn's shadow) of the low phase scans is ˜10 J m-2 K-1 s-1/2. With this value of the thermal inertia, the amplitude of the azimuthal temperature modulation is overestimated in our model as compared with those observed. This is likely to be because our model ignores inter-wake particles. The bolometric reflectance of wakes is estimated to be 0.35-0.40 although lower values are required to reproduce temperatures at low solar phase angles. This apparent phase dependence of the reflectance indicates that roughness on the wake surfaces is necessary.

Morishima, Ryuji; Spilker, Linda; Turner, Neal

2014-01-01

120

Acoustic Efficiency of Azimuthal Modes in Jet Noise Using Chevron Nozzles  

NASA Technical Reports Server (NTRS)

The link between azimuthal modes in jet turbulence and in the acoustic sound field has been examined in cold, round jets. Chevron nozzles, however, impart an azimuthal structure on the jet with a shape dependent on the number, length and penetration angle of the chevrons. Two particular chevron nozzles, with 3 and 4 primary chevrons respectively, and a round baseline nozzle are compared at both cold and hot jet conditions to determine how chevrons impact the modal structure of the flow and how that change relates to the sound field. The results show that, although the chevrons have a large impact on the azimuthal shape of the mean axial velocity, the impact of chevrons on the azimuthal structure of the fluctuating axial velocity is small at the cold jet condition and smaller still at the hot jet condition. This is supported by results in the azimuthal structure of the sound field, which also shows little difference in between the two chevron nozzles and the baseline nozzle in the distribution of energy across the azimuthal modes measured.

Brown, Clifford A.; Bridges, James

2006-01-01

121

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

2004-01-01

122

A Deterministic-Monte Carlo Hybrid Method for Time-Dependent Neutron Transport Problems  

SciTech Connect

A new deterministic-Monte Carlo hybrid solution technique is derived for the time-dependent transport equation. This new approach is based on dividing the time domain into a number of coarse intervals and expanding the transport solution in a series of polynomials within each interval. The solutions within each interval can be represented in terms of arbitrary source terms by using precomputed response functions. In the current work, the time-dependent response function computations are performed using the Monte Carlo method, while the global time-step march is performed deterministically. This work extends previous work by coupling the time-dependent expansions to space- and angle-dependent expansions to fully characterize the 1D transport response/solution. More generally, this approach represents and incremental extension of the steady-state coarse-mesh transport method that is based on global-local decompositions of large neutron transport problems. An example of a homogeneous slab is discussed as an example of the new developments.

Justin Pounders; Farzad Rahnema

2001-10-01

123

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

124

ATP- and glutathione-dependent transport of chemotherapeutic drugs by the multidrug resistance protein MRP1  

PubMed Central

The present study was performed to investigate the ability of the multidrug resistance protein (MRP1) to transport different cationic substrates in comparison with MDR1-P-glycoprotein (MDR1). Transport studies were performed with isolated membrane vesicles from in vitro selected multidrug resistant cell lines overexpressing MDR1 (A2780AD) or MRP1 (GLC4/Adr) and a MRP1-transfected cell line (S1(MRP)). As substrates we used 3H-labelled derivatives of the hydrophilic monoquaternary cation N-(4?,4?-azo-n-pentyl)-21-deoxy-ajmalinium (APDA), the basic drug vincristine and the more hydrophobic basic drug daunorubicin. All three are known MDR1-substrates. MRP1 did not mediate transport of these substrates per se. In the presence of reduced glutathione (GSH), there was an ATP-dependent uptake of vincristine and daunorubicin, but not of APDA, into GLC4/Adr and S1(MRP) membrane vesicles which could be inhibited by the MRP1-inhibitor MK571. ATP- and GSH-dependent transport of daunorubicin and vincristine into GLC4/Adr membrane vesicles was inhibited by the MRP1-specific monoclonal antibody QCRL-3. MRP1-mediated daunorubicin transport rates were dependent on the concentration of GSH and were maximal at concentrations ?10?mM. The apparent KM value for GSH was 2.7?mM. Transport of daunorubicin in the presence of 10?mM GSH was inhibited by MK571 with an IC50 of 0.4??M. In conclusion, these results demonstrate that MRP1 transports vincristine and daunorubicin in an ATP- and GSH-dependent manner. APDA is not a substrate for MRP1. PMID:10188979

Renes, Johan; de Vries, Elisabeth G E; Nienhuis, Edith F; Jansen, Peter L M; Muller, Michael

1999-01-01

125

One-dimensional virus transport in homogeneous porous media with time-dependent distribution coefficient  

Microsoft Academic Search

A stochastic model for one-dimensional virus transport in homogeneous, saturated, semi-infinite porous media is developed. The model accounts for first-order inactivation of liquid-phase and adsorbed viruses with different inactivation rate constants, and time-dependent distribution coefficient. It is hypothesized that the virus adsorption process is described by a local equilibrium expression with a stochastic time-dependent distribution coefficient. A closed form analytical

Constantinos V. Chrysikopoulos; Youn Sim

1996-01-01

126

Optimal Control using State Dependent Riccati Equation (SDRE) for a Flexible Cable Transporter System with Arbitrarily Varying Lengths  

E-print Network

Optimal Control using State Dependent Riccati Equation (SDRE) for a Flexible Cable Transporter dependent Riccati equation, Galerkin's method. I. INTRODUCTION Cable transporter systems are widely used-dependent Riccati equation. In this paper, we apply SDRE technique to propose an optimal controller for a flexible

Pota, Himanshu Roy

127

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. PMID:22172222

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

2011-01-01

128

Correlation between multiplicities in windows separated in azimuth and rapidity  

NASA Astrophysics Data System (ADS)

The forward-backward (FB) multiplicity correlations in two windows separated in rapidity and azimuth are analyzed in the framework of the model with independent identical sources (strings). Along with the short-range (SR) contribution, originating from the correlation between particles produced by a single string, the long-range (LR) contribution, originating from the fluctuation in the number of strings, is taken into account. The connection of the FB multiplicity correlation coefficient with the two-particle correlation function is traced. The dependencies of the correlation coefficient on the rapidity and azimuthal acceptance of the windows and on the corresponding gaps between them are studied. It is shown that the analysis of these dependencies enables to separate the contributions of two above mechanisms. The comparison of the results with the preliminary experimental data of ALICE shows the strong increase of the LR correlation with the growth of energy from 0.9 to 7 TeV, whereas the contribution of the SR correlations, characterizing the properties of a single source, remains practically the same. In the frame work of the model it corresponds to a three fold increase of the event-by-event fluctuations in the number of emitting sources (strings) with this growth of energy.

Vechernin, Vladimir

2014-07-01

129

Time-dependent radiation transport in a one-dimensional medium  

NASA Technical Reports Server (NTRS)

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

Nagel, W.; Meszaros, P.

1985-01-01

130

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

E-print Network

in the ionic form (Ag ), can enter freshwater rainbow trout via a Na channel situated on the branchial apicalATP-Dependent Silver Transport across the Basolateral Membrane of Rainbow Trout Gills N. R. Bury- brane of Rainbow Trout Gills. Bury, N. R., Grosell, M., Grover, A. K., and Wood, C. M. (1999). Toxicol

Grosell, Martin

131

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

132

A Temperature-Dependent Hartree Approach for Excess Proton Transport in Hydrogen-Bonded Chains  

E-print Network

A Temperature-Dependent Hartree Approach for Excess Proton Transport in Hydrogen-Bonded Chains R. I of an excess proton in a hydrogen-bonded chain, as found in biological systems. A quantum description of all the protons involved in making and breaking hydrogen bonds of the chain must be used; hence the utility

Cukier, Robert I.

133

Electron-Spin-Dependent Terahertz Light Transport in Spintronic-Plasmonic Media K. J. Chau,1  

E-print Network

Electron-Spin-Dependent Terahertz Light Transport in Spintronic-Plasmonic Media K. J. Chau,1 Mark is mediated by dipolar fields associated with induced surface charges (nonreso- nant particle plasmons) [1 opens the door to the marriage of spintronic and plasmonic technologies and could pave the way

Chau, Kenneth

134

Functional assembly of thylakoid DpH-dependent/Tat protein transport pathway components in vitro  

E-print Network

Functional assembly of thylakoid DpH-dependent/Tat protein transport pathway components in vitro and Cellular Biology, University of Florida, Gainesville, USA Assembly of the components of the thylakoid Dp Tat pathway precursor pro- teins. The amounts assembled into thylakoids by this pro- cedure were

135

Passive Ca 2+ Transport and Ca 2+ Dependent K + Transport in Plasmodium falciparum Infected Red Cells  

Microsoft Academic Search

.   Previous reports have indicated that Plasmodium falciparum-infected red cells (pRBC) have an increased Ca2+ permeability. The magnitude of the increase is greater than that normally required to activate the Ca2+-dependent K+ channel (K\\u000a \\u000a \\u000a \\u000a Ca\\u000a \\u000a channel) of the red cell membrane. However, there is evidence that this channel remains inactive in pRBC. To clarify this\\u000a discrepancy, we have reassessed both

H. M. Staines; W. Chang; J. C. Ellory; T. Tiffert; K. Kirk; V. L. Lew

1999-01-01

136

Glutamate transporter-dependent mTOR phosphorylation in M?ller glia cells  

PubMed Central

Glu (glutamate), the excitatory transmitter at the main signalling pathway in the retina, is critically involved in changes in the protein repertoire through the activation of signalling cascades, which regulate protein synthesis at transcriptional and translational levels. Activity-dependent differential gene expression by Glu is related to the activation of ionotropic and metabotropic Glu receptors; however, recent findings suggest the involvement of Na+-dependent Glu transporters in this process. Within the retina, Glu uptake is aimed at the replenishment of the releasable pool, and for the prevention of excitotoxicity and is carried mainly by the GLAST/EAAT-1 (Na+-dependent glutamate/aspartate transporter/excitatory amino acids transporter-1) located in Müller radial glia. Based on the previous work showing the alteration of GLAST expression induced by Glu, the present work investigates the involvement of GLAST signalling in the regulation of protein synthesis in Müller cells. To this end, we explored the effect of D-Asp (D-aspartate) on Ser-2448 mTOR (mammalian target of rapamycin) phosphorylation in primary cultures of chick Müller glia. The results showed that D-Asp transport induces the time- and dose-dependent phosphorylation of mTOR, mimicked by the transportable GLAST inhibitor THA (threo-?-hydroxyaspartate). Signalling leading to mTOR phosphorylation includes Ca2+ influx, the activation of p60src, phosphatidylinositol 3-kinase, protein kinase B, mTOR and p70S6K. Interestingly, GLAST activity promoted AP-1 (activator protein-1) binding to DNA, supporting a function for transporter signalling in retinal long-term responses. These results add a novel receptor-independent pathway for Glu signalling in Müller glia, and further strengthen the critical involvement of these cells in the regulation of glutamatergic transmission in the retina. PMID:22817638

Maria Lopez-Colome, Ana; Martinez-Lozada, Zila; Guillem, Alain M; Lopez, Edith; Ortega, Arturo

2012-01-01

137

Linear Approximation SAR Azimuth Processing Study  

NASA Technical Reports Server (NTRS)

A segmented linear approximation of the quadratic phase function that is used to focus the synthetic antenna of a SAR was studied. Ideal focusing, using a quadratic varying phase focusing function during the time radar target histories are gathered, requires a large number of complex multiplications. These can be largely eliminated by using linear approximation techniques. The result is a reduced processor size and chip count relative to ideally focussed processing and a correspondingly increased feasibility for spaceworthy implementation. A preliminary design and sizing for a spaceworthy linear approximation SAR azimuth processor meeting requirements similar to those of the SEASAT-A SAR was developed. The study resulted in a design with approximately 1500 IC's, 1.2 cubic feet of volume, and 350 watts of power for a single look, 4000 range cell azimuth processor with 25 meters resolution.

Lindquist, R. B.; Masnaghetti, R. K.; Belland, E.; Hance, H. V.; Weis, W. G.

1979-01-01

138

Azimuthally-structured radio beams of pulsars  

NASA Astrophysics Data System (ADS)

There is a growing evidence that radio beams of some pulsars are azimuthally-structured. When viewed down the dipole axis, the beam resembles spokes in a wheel, with narrow emission stripes spreading away from the dipole axis. I will present objects for which the spoke-like model describes their profiles more successfully than the traditional conal geometry. Further from the dipole axis, the stripes do not widen as would be expected for a structure limited by lines of fixed magnetic azimuth. Hence the mathematical formulae that describe the beam do not result from a simple projection of dipolar field lines on the sky. With the ambiguity of pulsar geometry determination through the gamma-ray- or polarisation-based methods, the task is hindered by the unknown radio beam geometry, and the conal interpretation of profiles can be misleading.

Dyks, Jaroslaw

139

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

SciTech Connect

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

Chacon, Luis [ORNL; Del-Castillo-Negrete, Diego B [ORNL; Hauck, C. [Oak Ridge National Laboratory (ORNL)

2014-01-01

140

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

141

Time-dependent single-collision kernels for integral transport theory  

SciTech Connect

The authors discuss time-dependent integral transport equation single-collision kernels for one-dimensional geometries corresponding to the steady-state single-collision kernels found in the available literature calculated by making use of the Laplace transform technique, simple geometric transformation relationships, and point kernel integrations. Using the convolution theorem, the time-dependent scalar flux is obtained by convoluting the single-collision kernel with the time-dependent source. Using the multiple collision formulation of the integral transport solution isotropic sources thar are delta distributions in time are considered in several examples. Analytical solutions for the uncollided and first-collided scalar fluxes are obtained for a boundary source having an isotropic angular distribution directed into a semi-infinite medium and into a slab of thickness b and for a point source at the origin of an infinite medium and finite sphere of radius a.

Henderson, D.L.; Maynard, C.W. (Univ. of Wisconsin, Madison, Nuclear Engineering and Engineering Physics, WI (US))

1989-06-01

142

Inorganic cation dependence of putrescine and spermidine transport in human breast cancer cells.  

PubMed

The mechanism of polyamine uptake in mammalian cells is still poorly understood. The role of inorganic cations in polyamine transport was investigated in ZR-75-1 human breast cancer cells. Although strongly temperature dependent, neither putrescine nor spermidine uptake was mediated by a Na+ cotransport mechanism. In fact, Na+ and cholinium competitively inhibited putrescine uptake relative to that measured in a sucrose-based medium. On the other hand, ouabain, H+, Na+, and Ca2+ ionophores, as well as dissipation of the K+ diffusion potential, strongly inhibited polyamine uptake in keeping with a major role of membrane potential in that process. Polyamine transport was inversely dependent on ambient osmolality at near physiological values. Putrescine transport was inhibited by 70% by decreasing extracellular pH from 7.2 to 6.2, whereas spermidine uptake had a more acidic optimum. Deletion of extracellular Ca2+ inhibited putrescine uptake more strongly than chelation of intracellular Ca2+. In fact, bound divalent cations were absolutely required for polyamine transport, as shown after brief chelation of the cell monolayers with EDTA. Either Mn2+, Ca2+, or Mg2+ sustained putrescine uptake activity with high potency (Km = 50-300 microM). Mn2+ was a much stronger activator of spermidine than putrescine uptake, suggesting a specific role for this metal in polyamine transport. Other transition metals (Co2+, Ni2+, Cu2+, and Zn2+) were mixed activators/antagonists of carrier activity, while Sr2+ and Ba2+ were very weak agonists, while not interfering with Ca2+/Mg(2+)-dependent transport. Thus, polyamine uptake in human breast tumor cells is negatively affected by ionic strength and osmolality, and is driven, at least in part, by the membrane potential, but not by the Na+ electrochemical gradient. Moreover, the polyamine carrier, or a tightly coupled accessory component, appears to have a high-affinity binding site for divalent cations, which is essential for the uptake mechanism. PMID:7530245

Poulin, R; Lessard, M; Zhao, C

1995-01-27

143

Temperature Dependence of the Charge Transport in a C60 based Organic Field Effect Transistor  

NASA Astrophysics Data System (ADS)

We studied the temperature dependence of the electron transport in C60 based Organic Field Effect Transistors (OFETs). On the spin-coated bottom gate dielectric, the semi-conducting C60 thin-film has been grown by standard evaporation technique. Device parameters as the threshold voltage, the field effect mobility and the activation energy of the electron transport were determined in the temperature range from 300 K to 77 K. The field effect mobility obeys the Meyer-Neldel Rule (MNR), which is an empirical relation between activation energy and the mobility prefactor.

Ullah, Mujeeb; Singh, Th. B.; Matt, G. J.; Simbruner, C.; Hernandz-Sosa, G.; Sariciftci, S. N.; Sitter, H.

144

Polarization-Dependent Selective Transport to the Apical Membrane by KIF5B in MDCK Cells  

PubMed Central

SUMMARY Microtubule-based vesicular transport is well documented in epithelial cells, but the specific motors involved and their regulation during polarization are largely unknown. We demonstrate that KIF5B mediates post-Golgi transport of an apical protein in epithelial cells, but only after polarity has developed. Time-lapse imaging of EB1-GFP in polarized MDCK cells showed microtubule plus ends growing toward the apical membrane, implying that plus end-directed N-kinesins might be used to transport apical proteins. Indeed, time-lapse microscopy revealed that expression of a KIF5B dominant negative or microinjection of function-blocking KIF5 antibodies inhibited selectively post-Golgi transport of the apical marker, p75-GFP, after polarization of MDCK cells. Expression of other KIF dominant negatives did not alter p75-GFP trafficking. Immunoprecipitation experiments demonstrated an interaction between KIF5B and p75-GFP in polarized, but not in subconfluent, MDCK cells. Our results demonstrate that apical protein transport depends on selective microtubule motors and that epithelial cells switch kinesins for post-Golgi transport during acquisition of polarity. PMID:17925227

Jaulin, Fanny; Xue, Xiaoxiao; Rodriguez-Boulan, Enrique; Kreitzer, Geri

2007-01-01

145

Kinetics and stoichiometry of Na-dependent Li transport in human red blood cells  

PubMed Central

This paper describes the kinetics and stoichiometry of a tightly coupled Na-Li exchange transport system in human red cells. The system is inhibited by phloretin and furosemide but not by ouabain. Li influx by this system increases and saturates with increasing concentrations of external Li and internal Na and is inhibited competitively by external Na. Comparable functions relate Li efflux and Na efflux to internal and external Li and Na concentrations. Analysis of these relations yields the following values for the ion concentrations required to half-maximally activate the transport system: internal Na and Li 9.0 and 0.5 mM, respectively, external Na and Li 25 and 1.5 mM, respectively. The system performs a 1:1 exchange of Na and Li moving in opposite directions across the red cell membrane. We found no evidence for a simultaneous transport of more than one Na and Li by the system. The maximum transport rate of Na-dependent Li transport varied between 0.1 and 0.37 mmol/(liter of cells X h) in the red cells of the five normal male subjects studied. No significant variations between individual subjects were observed for bicarbonate-stimulated Li transport and for the residual Li fluxes which occur in the absence of bicarbonate and in the presence of ouabain plus phloretin. PMID:690598

1978-01-01

146

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

147

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

NASA Astrophysics Data System (ADS)

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.; Mikkelsen, D. R.; White, A. E.; Reinke, M. L.; Ernst, D.; Podpaly, Y.; Candy, J.

2012-05-01

148

Uptake of the anthracycline pirarubicin into mouse M5076 ovarian sarcoma cells via a sodium-dependent nucleoside transport system  

Microsoft Academic Search

Purpose We have previously demonstrated that the cytotoxicity of anthracyclines, pirarubicin (THP) and doxorubicin (DOX), is partially dominated by their intracellular amounts, which depend on the uptake efficacy of transporter(s). To clarify their transport mechanism, we examined whether or not Na +\\/nucleoside cotransporter (CNT) is involved in the uptake of THP by M5076 cells. Methods Expression of the CNT isoforms

Katsuhito Nagai; Kazuki Nagasawa; Sadaki Fujimoto

2005-01-01

149

Grey transport acceleration method for time-dependent radiative transfer problems  

SciTech Connect

A new iterative method for solving hte time-dependent multifrequency radiative transfer equations is described. The method is applicable to semi-implicit time discretizations that generate a linear steady-state multifrequency transport problem with pseudo-scattering within each time step. The standard ''lambda'' iteration method is shown to often converge slowly for such problems, and the new grey transport acceleration (GTA) method, based on accelerating the lambda method by employing a grey, or frequency-independent transport equation, is developed. The GTA method is shown, theoretically by an iterative Fourier analysis, and experimentally by numerical calculations, to converge significantly faster than the lambda method. In addition, the GTA method is conceptually simple to implement for general differencing schemes, on either Eulerian or Lagrangian meshes. copyright 1988 Academic Press, Inc.

Larsen, E.

1988-10-01

150

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

151

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

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

152

Azimuthal Anisotropy of Light Extraction from Photonic Crystal Light-emitting Diodes  

Microsoft Academic Search

Photonic crystal light-emitting diodes exhibiting anisotropic light extraction efficiency have been investigated experimentally and theoretically. Images of the anisotropy in the azimuthal direction are obtained using annular structures with triangular lattice. Depending on the lattice constants, 6-fold symmetric patterns with varying number of petals are obtained.

H. T. Hsueh; J.-F. T. Wang; C. H. Chao; W. Y. YehandJ; J. Y. Chi; C. F. Lai; H. C. Kuo; T. C. Lu; S. C. Wang

2007-01-01

153

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

PubMed Central

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

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

1993-01-01

154

Time-dependent density functional theory quantum transport simulation in non-orthogonal basis  

SciTech Connect

Basing on the earlier works on the hierarchical equations of motion for quantum transport, we present in this paper a first principles scheme for time-dependent quantum transport by combining time-dependent density functional theory (TDDFT) and Keldysh's non-equilibrium Green's function formalism. This scheme is beyond the wide band limit approximation and is directly applicable to the case of non-orthogonal basis without the need of basis transformation. The overlap between the basis in the lead and the device region is treated properly by including it in the self-energy and it can be shown that this approach is equivalent to a lead-device orthogonalization. This scheme has been implemented at both TDDFT and density functional tight-binding level. Simulation results are presented to demonstrate our method and comparison with wide band limit approximation is made. Finally, the sparsity of the matrices and computational complexity of this method are analyzed.

Kwok, Yan Ho; Xie, Hang; Yam, Chi Yung; Chen, Guan Hua, E-mail: ghc@everest.hku.hk [Department of Chemistry, The University of Hong Kong, Pokfulam Road (Hong Kong); Zheng, Xiao [Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui 230026 (China)] [Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui 230026 (China)

2013-12-14

155

Modelling charge sign dependent modulation of cosmic rays with stochastic transport models  

NASA Astrophysics Data System (ADS)

It is well established that cosmic rays (CRs), as charged particles, undergo gradient, curvature and neutral sheet drifts in the large scale heliospheric magnetic field (HMF). With the HMF polarity switching every ~22 years, the CR drift field also switches direction, leading to so-called charge-sign dependent modulation; drifts depend on both the polarity of the HMF and the charge of the CR particles. With this effect included in modulation models, the complexity of the resulting transport equation necessitates a numerical solution. A numerical scheme that has become fashionable in recent times is the implementation of stochastic differential equations (SDEs). We review this numerical scheme as well as some of the various applications of SDEs to the heliospheric transport of CRs. We also discuss the effectiveness of a SDE based modulation mode in reproducing drift effects, as well as the additional insights gained from using such a numerical technique.

Toit Strauss, Du; Potgieter, Marius

2012-07-01

156

pH-dependent transport of metals through a reactive porous medium  

NASA Astrophysics Data System (ADS)

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

Prigiobbe, V.; Bryant, S. L.

2013-12-01

157

Scale-and shape-dependent transport property of nanoporous materials  

NASA Astrophysics Data System (ADS)

A cellular material was proposed as an ideal candidate for multifunctional material achieving various optimal properties in many length scales. The superior performances on mechanical, thermal, electrical, and fluidic properties have been explored in analytic, numerical, and experimental studies. Since the cellular materials have wide range of potential applications in microscopic devices, characterization in small length scale gains more attentions recently. For this assessment, the atomistic approach as well as continuum approach becomes crucial to characterize its performance in multiscales. One of the key multifunctional features of the nanoporous microstructures would be high fluidic performance. Some studies investigated macroscopic transport properties, but less has been done to address the scale- and shape-dependent transport properties for their microscopic fluidics applications. In this study, we investigated complex flow patterns and transport properties of porous structures in microscopic scales. To address the geometry-dependent transport properties, a non-equilibrium molecular dynamics was employed in the atomistic scale. Various flow channels in the porous materials were introduced to address the size and shape effect of the flow patterns in small length scales.

Hyun, Sangil; Koo, Eunhae

2013-02-01

158

Azimuth orientation of the dragonfly (Sympetrum)  

NASA Technical Reports Server (NTRS)

Evidence is presented of directional orientation by an alighting dragonfly relative to the azimuth of the sun. The effects of wind direction on this orientation are analyzed. It was concluded that wind does not play a major role in orientation but may have some secondary function in helping greater numbers of dragonflies face windward more often than leeward. A search was made to find the principle sensory receptor for orientation. Two possibilities, the large compound eye and the frontal ocelli, were noted; however, no conclusive evidence could be found.

Hisada, M.

1972-01-01

159

Transmission and Reflection in the Stadium Billiard: Time-dependent asymmetric transport  

E-print Network

We investigate the transmission and reflection survival probabilities for the chaotic stadium billiard with two holes placed asymmetrically. Classically, these distributions are shown to have algebraic or exponential decays depending on the choice of injecting hole and exact expressions are given for the first time and confirmed numerically. As there is no reported quantum theoretical or experimental analogue we propose a model for experimental observation of the asymmetric transport using semiconductor nano-structures and comment on the relevant quantum time-scales.

Carl P. Dettmann; Orestis Georgiou

2010-06-07

160

One-dimensional virus transport in porous media with time-dependent inactivation rate coefficients  

Microsoft Academic Search

A model for virus transport in one-dimensional, homogeneous, saturated porous media is developed, accounting for virus sorption and inactivation of liquid phase and adsorbed viruses with different time dependent rate coefficients. The virus inactivation process is represented by a pseudo first-order rate expression. The pseudo first-order approximation is shown to simulate available experimental data from three virus inactivation batch studies

Youn Sim; Constantinos V. Chrysikopoulos

1996-01-01

161

Temperature dependence of transport and equilibrium properties of alkylpyridinium surfactants in aqueous solutions  

Microsoft Academic Search

Conductivity measurements at varying concentrations and temperatures for two alkyl pyridinium surfactants-dodecylpyridinium chloride (DPC) and cetylpyridinium chloride (CPC) in aqueous medium have been performed. The resulting data in the lower concentration range were used for the determination of limiting transport parameters of the surfactant ions. Temperature dependence of limiting ion conductance ?+(surf.cation)? and limiting ion mobility u+(surf.cation)? of surfactant ions

Mohsin Ahmad Bhat; Aijaz Ahmed Dar; Adil Amin; Peer Irfan Rashid; Ghulam Mohammad Rather

2007-01-01

162

Parametric dependence of turbulent particle transport in high density electron heated FTU plasmas  

Microsoft Academic Search

In this paper we present the result of a study carried out at the Frascati Tokamak Upgrade (FTU), on a set of full non-inductive current driven, electron heated, L-mode discharges aimed at investigating the parametric dependence of the electron density profile on the electron temperature and safety factor gradients as predicted by quasi-linear drift-turbulence transport theory. Experiments in FTU allow

M. Romanelli; G. T. Hoang; C. Bourdelle; C. Gormezano; E. Giovannozzi; M. Leigheb; M. Marinucci; D. Marocco; C. Mazzotta; L. Panaccione; V. Pericoli; G. Regnoli; O. Tudisco

2007-01-01

163

ATP-Dependent Transport of Organic Anions in Secretory Vesicles of Saccharomyces cerevisiae  

Microsoft Academic Search

Secretory mutants (sec1, sec6) of Saccharomyces cerevisiae accumulate large pools of secretory vesicles at the restrictive temperature (37^circC) because of a block in the delivery of vesicles to the cell surface. We report that secretory vesicles isolated from sec mutants exhibit ATP-dependent uptake of two classes of organic anions that are substrates for the canalicular carriers of mammalian liver. Transport

Marie V. St-Pierre; Stephan Ruetz; Linda F. Epstein; Philippe Gros; Irwin M. Arias

1994-01-01

164

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

PubMed Central

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

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

2013-01-01

165

Growth temperature dependence of transport properties of InAs epilayers grown on GaP  

E-print Network

with a lattice mismatch of 7%. In the present study, InAs was grown on the wide-band-gap semiconductor GaPGrowth temperature dependence of transport properties of InAs epilayers grown on GaP Victor Souwa 23 June 2000 Undoped InAs was grown by molecular-beam epitaxy directly on GaP at a set of different

Woodall, Jerry M.

166

Cadmium Binding and Sodium-Dependent Solute Transport in Renal Brush-Border Membrane Vesicles  

Microsoft Academic Search

Exposure to cadmium (Cd) impairs renal transport systems for glucose, amino acids, phosphate, and dicarboxylates. To investigate if these changes are directly related to a Cd binding to the renal brush-border membrane, Cd binding and the Na+-dependent uptakes ofd-glucose,l-alanine, phosphate, and succinate were determined in rat renal brush-border membrane vesicles (BBMV) exposed to CdCl2. Cd uptake by BBMV showed time

Do Whan Ahn; Young Mook Kim; Kyoung Ryong Kim; Yang Saeng Park

1999-01-01

167

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

E-print Network

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

Rodolphe Chabreyrie; Stefan G. Llewellyn Smith

2014-05-08

168

Activity Dependent O+ Transport Paths From the Ionosphere to the Ring Current  

NASA Astrophysics Data System (ADS)

Energetic O+ has important dynamic effects on the ring current. Insights into the effects of O+ on ring current dynamics have come primarily from models, not observations. Here we report observations made on the Polar spacecraft by the Toroidal Imaging Mass-Angle Spectrograph (TIMAS) which has measured the flux and energy distribution of escaping O+, cast in auroral boundary coordinates. Comparison with ISEE -1 observations of O+ in the plasma sheet, other recent observations, and multi-fluid simulations of the magnetosphere suggest that there are two distinct pathways for the energization and transport of O+ from the dayside ionosphere to the plasma sheet: 1) Energization and transport over the polar cap into the central plasma sheet which our analysis suggests is significant only during geomagnetically active times; and 2) Energization and transport in three dimensional magnetospheric fields during geomagnetically quiet times that leads to a significant O+ population on the plasma sheet flanks. The consequences of the suggested activity-dependant O+ transport path and transport of O+ in boundary related coordinates have not been previously explored.

Peterson, W.; Andersson, L.; Callahan, B.; Elkington, S.; Winglee, R.; Scudder, J.; Collin, H.

2007-12-01

169

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

170

GGA2- and Ubiquitin-dependent Trafficking of Arn1, the Ferrichrome Transporter of Saccharomyces cerevisiae  

PubMed Central

The intracellular trafficking of Arn1, a ferrichrome transporter in Saccharomyces cerevisiae, is controlled in part by the binding of ferrichrome to the transporter. In the absence of ferrichrome, Arn1 is sorted directly from the Golgi to endosomes. Ferrichrome binding triggers the redistribution of Arn1 to the plasma membrane, whereas ferrichrome transport is associated with the cycling of Arn1 between the plasma membrane and endosomes. Here, we report that the clathrin adaptor Gga2 and ubiquitination by the Rsp5 ubiquitin ligase are required for trafficking of Arn1. Gga2 was required for Golgi-to-endosomal trafficking of Arn1, which was sorted from endosomes to the vacuole for degradation. Trafficking into the vacuolar lumen was dependent on ubiquitination by Rsp5, but ubiquitination was not required for plasma membrane accumulation of Arn1 in the presence of ferrichrome. Retrograde trafficking via the retromer complex or Snx4 was also not required for plasma membrane accumulation. High concentrations of ferrichrome led to higher levels of ubiquitination of Arn1, but they did not induce degradation. Without this ubiquitination, Arn1 remained on the plasma membrane, where it was active for transport. Arn1 was preferentially modified with polyubiquitin chains on a cluster of lysine residues at the amino terminus of the transporter. PMID:17344478

Kim, Youngwoo; Deng, Yi

2007-01-01

171

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

2013-10-01

172

Substrate-Dependent Ligand Inhibition of the Human Organic Cation Transporter OCT2  

PubMed Central

Organic cation transporter 2 (OCT2) mediates the initial step in renal secretion of organic cations: uptake from the blood, across the basolateral membrane, and into the renal proximal tubule cells. Because of its potential as a target for unwanted drug-drug interactions (DDIs), considerable attention has been directed toward understanding the basis of OCT2 selectivity. These studies typically assess selectivity based on ligand inhibition profiles for OCT2-mediated transport of a probe substrate. However, little attention has been given to the potential influence of the substrate on the profile of ligand inhibition. Here we compared the IC50 values obtained for a set of structurally distinct inhibitors against OCT2-mediated transport of three structurally distinct substrates: 1-methyl-4-phenylpyridinium (MPP); metformin; and a novel fluorescent substrate, N,N,N-trimethyl-2-[methyl(7-nitrobenzo[c][l,2,5]oxadiazol-4-yl)amino]ethanaminium iodide (NBD-MTMA). The median IC50 value for inhibition of MPP transport was 9-fold higher than that for inhibition of metformin transport. Similarly, the median IC50 value for inhibition of MPP transport was 5-fold higher than that for NBD-MTMA transport. However, this was not a systematic difference in inhibitory efficacy; the ratio of IC50 values, MPP versus NBD-MTMA, ranged from 88-fold (ipratropium) to 0.3-fold (metformin). These data show that 1) the choice of OCT2 substrate significantly influences both quantitative and qualitative inhibitory interactions with cationic drugs; and 2) ligand interactions with OCT2 are not restricted to competition for a common ligand binding site, consistent with a binding surface characterized by multiple, possibly overlapping interaction sites. Development of predictive models of DDIs with OCT2 must take into account the substrate dependence of ligand interaction with this protein. PMID:23709117

Belzer, Mathew; Morales, Mark; Jagadish, Bhumasamudram; Mash, Eugene A.

2013-01-01

173

Substrate-dependent ligand inhibition of the human organic cation transporter OCT2.  

PubMed

Organic cation transporter 2 (OCT2) mediates the initial step in renal secretion of organic cations: uptake from the blood, across the basolateral membrane, and into the renal proximal tubule cells. Because of its potential as a target for unwanted drug-drug interactions (DDIs), considerable attention has been directed toward understanding the basis of OCT2 selectivity. These studies typically assess selectivity based on ligand inhibition profiles for OCT2-mediated transport of a probe substrate. However, little attention has been given to the potential influence of the substrate on the profile of ligand inhibition. Here we compared the IC50 values obtained for a set of structurally distinct inhibitors against OCT2-mediated transport of three structurally distinct substrates: 1-methyl-4-phenylpyridinium (MPP); metformin; and a novel fluorescent substrate, N,N,N-trimethyl-2-[methyl(7-nitrobenzo[c][l,2,5]oxadiazol-4-yl)amino]ethanaminium iodide (NBD-MTMA). The median IC50 value for inhibition of MPP transport was 9-fold higher than that for inhibition of metformin transport. Similarly, the median IC50 value for inhibition of MPP transport was 5-fold higher than that for NBD-MTMA transport. However, this was not a systematic difference in inhibitory efficacy; the ratio of IC50 values, MPP versus NBD-MTMA, ranged from 88-fold (ipratropium) to 0.3-fold (metformin). These data show that 1) the choice of OCT2 substrate significantly influences both quantitative and qualitative inhibitory interactions with cationic drugs; and 2) ligand interactions with OCT2 are not restricted to competition for a common ligand binding site, consistent with a binding surface characterized by multiple, possibly overlapping interaction sites. Development of predictive models of DDIs with OCT2 must take into account the substrate dependence of ligand interaction with this protein. PMID:23709117

Belzer, Mathew; Morales, Mark; Jagadish, Bhumasamudram; Mash, Eugene A; Wright, Stephen H

2013-08-01

174

New aspect of renal phosphate reabsorption: the type IIc sodium-dependent phosphate transporter.  

PubMed

Abnormalities of the inorganic phosphate (Pi) reabsorption in the kidney result in various metabolic disorders. Na+-dependent Pi (Na/Pi) transporters in the brush border membrane of proximal tubular cells mediate the rate-limiting step in the overall Pi-reabsorptive process. Type IIa and type IIc Na/Pi cotransporters are expressed in the apical membrane of proximal tubular cells and mediate Na/Pi cotransport; the extent of Pi reabsorption in the proximal tubules is determined largely by the abundance of the type IIa Na/Pi cotransporter. However, several studies suggest that the type IIc cotransporter in Pi reabsorption may also play a role in this process. For example, mutation of the type IIc Na/Pi cotransporter gene results in hereditary hypophosphatemic rickets with hypercalciuria, suggesting that the type IIc transporter plays an important role in renal Pi reabsorption in humans and may be a key determinant of the plasma Pi concentration. The type IIc Na/Pi transporter is regulated by parathyroid hormone, dietary Pi, and fibroblast growth factor 23, and studies suggest a differential regulation of the IIa and IIc transporters. Indeed, differences in temporal and/or spatial expression of the type IIa and type IIc Na/Pi transporters may be required for normal phosphate homeostasis and bone development. This review will briefly summarize the regulation of renal Pi transporters in various Pi-wasting disorders and highlight the role of a relatively new member of the Na/Pi cotransporter family: the type IIc Na/Pi transporter/SLC34A3. PMID:17687185

Miyamoto, Ken-ichi; Ito, Mikiko; Tatsumi, Sawako; Kuwahata, Masashi; Segawa, Hiroko

2007-01-01

175

The AMOS (Azimuthal MOde Simulator) wakefield code  

SciTech Connect

AMOS (Azimuthal MOde Simulator) is an electromagnetic simulation computer program that has been developed to study and design accelerator cavities. AMOS simulates the temporal evolution of fields in rotationally symmetric volumes, using a harmonic expansion in the azimuthal coordinate ({phi}) to project the fields onto a two-dimensional, r {minus} z, finite-difference grid. An interactive preprocessor has been developed which allows the user to easily construct AMOS grids from geometric models. A wakefield postprocessor has also been developed to compute wake potentials and impedances from AMOS time-domain data. Graphical postprocessing software is presently under development. AMOS has been used to study accelerating modules in several linear accelerators, including the Advanced Test Accelerator (ATA), the Experimental Test Accelerator-II (ETA-II), SNOMAD, Dual Access Radiographic Hydrodynamics Test facility (DARHT), and others. Ongoing AMOS development objectives include the installation of an open'' boundary condition (Lindman), an rf tensor ferrite model, and the extension of AMOS to irregular, boundary conforming grids. 9 refs., 10 figs., 1 tab.

DeFord, J.F.; Craig, G.D.; McLeod, R.R.

1990-01-23

176

Functional Implications and Ubiquitin-Dependent Degradation of the Peptide Transporter Ptr2 in Saccharomyces cerevisiae.  

PubMed

The peptide transporter Ptr2 plays a central role in di- or tripeptide import in Saccharomyces cerevisiae. Although PTR2 transcription has been extensively analyzed in terms of upregulation by the Ubr1-Cup9 circuit, the structural and functional information for this transporter is limited. Here we identified 14 amino acid residues required for peptide import through Ptr2 based on the crystallographic information of Streptococcus thermophilus peptide transporter PepTst and based on the conservation of primary sequences among the proton-dependent oligopeptide transporters (POTs). Expression of Ptr2 carrying one of the 14 mutations of which the corresponding residues of PepTst are involved in peptide recognition, salt bridge interaction, or peptide translocation failed to enable ptr2?trp1 cell growth in alanyl-tryptophan (Ala-Trp) medium. We observed that Ptr2 underwent rapid degradation after cycloheximide treatment (half-life, approximately 1 h), and this degradation depended on Rsp5 ubiquitin ligase. The ubiquitination of Ptr2 most likely occurs at the N-terminal lysines 16, 27, and 34. Simultaneous substitution of arginine for the three lysines fully prevented Ptr2 degradation. Ptr2 mutants of the presumed peptide-binding site (E92Q, R93K, K205R, W362L, and E480D) exhibited severe defects in peptide import and were subjected to Rsp5-dependent degradation when cells were moved to Ala-Trp medium, whereas, similar to what occurs in the wild-type Ptr2, mutant proteins of the intracellular gate were upregulated. These results suggest that Ptr2 undergoes quality control and the defects in peptide binding and the concomitant conformational change render Ptr2 subject to efficient ubiquitination and subsequent degradation. PMID:25172766

Kawai, Ken; Moriya, Atsuto; Uemura, Satoshi; Abe, Fumiyoshi

2014-11-01

177

The molecular mechanism of ion-dependent gating in secondary transporters.  

PubMed

LeuT-like fold Na-dependent secondary active transporters form a large family of integral membrane proteins that transport various substrates against their concentration gradient across lipid membranes, using the free energy stored in the downhill concentration gradient of sodium ions. These transporters play an active role in synaptic transmission, the delivery of key nutrients, and the maintenance of osmotic pressure inside the cell. It is generally believed that binding of an ion and/or a substrate drives the conformational dynamics of the transporter. However, the exact mechanism for converting ion binding into useful work has yet to be established. Using a multi-dimensional path sampling (string-method) followed by all-atom free energy simulations, we established the principal thermodynamic and kinetic components governing the ion-dependent conformational dynamics of a LeuT-like fold transporter, the sodium/benzyl-hydantoin symporter Mhp1, for an entire conformational cycle. We found that inward-facing and outward-facing states of Mhp1 display nearly the same free energies with an ion absent from the Na2 site conserved across the LeuT-like fold transporters. The barrier separating an apo-state from inward-facing or outward-facing states of the transporter is very low, suggesting stochastic gating in the absence of ion/substrate bound. In contrast, the binding of a Na2 ion shifts the free energy stabilizing the outward-facing state and promoting substrate binding. Our results indicate that ion binding to the Na2 site may also play a key role in the intracellular thin gate dynamics modulation by altering its interactions with the transmembrane helix 5 (TM5). The Potential of Mean Force (PMF) computations for a substrate entrance displays two energy minima that correspond to the locations of the main binding site S1 and proposed allosteric S2 binding site. However, it was found that substrate's binds to the site S1 ?5 kcal/mol more favorable than that to the site S2 for all studied bound combinations of ions and a substrate. PMID:24204233

Zhao, Chunfeng; Noskov, Sergei Yu

2013-10-01

178

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

179

Astrocytic glutamate transporter-dependent neuroprotection against glutamate toxicity: an in vitro study of maslinic acid.  

PubMed

The astrocytic glutamate transporters GLAST/EAAT1 and GLT-1/EAAT2 are crucial for the removal of glutamate from the synaptic cleft and are essential for maintaining a low concentration of extracellular glutamate in the brain. Enhanced transporter expression is neuroprotective. In the present study, we tested the neuropotective effects of maslinic acid, a natural product from the Olea europaea plant, on cultures of primary neurons from the cerebral cortex. Studies showed that astrocyte-conditioned medium from maslinic acid-treated astrocytes dose-dependently promoted neuron survival during glutamate toxicity by enhancing extracellular glutamate clearance. Real-time PCR and western blot analysis revealed that maslinic acid pre-treatment significantly increased the expression of GLAST and GLT-1 at the protein and mRNA levels. In addition, this neuroprotection was abolished by the glutamate transporter inhibitor, L-Threohydroxy aspartate (THA), in a co-culture of astrocytes and neurons. These findings suggest that maslinic acid regulates the extracellular glutamate concentration by increasing the expression of astrocytic glutamate transporters, which may, in turn, provide neuroprotection. PMID:21118675

Qian, Yisong; Guan, Teng; Tang, Xuzhen; Huang, Longfei; Huang, Menghao; Li, Yunman; Sun, Hongbin; Yu, Rong; Zhang, Fan

2011-01-25

180

Development of a scintillation proximity assay for analysis of Na+/Cl- -dependent neurotransmitter transporter activity.  

PubMed

Human placental choriocarcinoma (JAR) cells endogenously expressing glycine transporter type 1a (GlyT1a) have been cultured in 96-well scintillating microplates to develop a homogenous screening assay for the detection of GlyT1 antagonists. In these microplates uptake of [14C]glycine was time dependent and saturable with a Michaelis-Menten constant (Km) of 27+/-3 microM. The GlyT1 transport inhibitors sarcosine, ALX-5407, and Org-24598 were tested and shown to block [14C]glycine uptake with expected IC50 values of 37.5+/-4.6 microM, 2.8+/-0.6 nM, and 6.9+/-0.9 nM, respectively. The [14C]glycine uptake process was sensitive to membrane Na+ gradient as blockade of membrane Na+/K+-ATPase by ouabain or Na+ exchanger by benzamil-disrupted glycine accumulation in JAR cells. Glycine influx was not affected by concentration of dimethyl sulfoxide up to 2%. The versatility of this technological approach was further confirmed by the characterization of a saturable [14C]taurine uptake in JAR cells. Taurine transport was of high affinity with a Km of 10.2+/-1.7 microM and fully inhibited by ALX-5407 (IC50=522 +/-83 nM). The developed assay is homogenous, rapid, versatile and amenable to automation for the discovery of new neurotransmitter transporter inhibitors. PMID:12963052

Williams, Jacinta B; Mallorga, Pierre J; Lemaire, Wei; Williams, David L; Na, Sang; Patel, Smita; Conn, P Jeffrey; Conn, Jeffrey P; Pettibone, Douglas J; Austin, Christopher; Sur, Cyrille

2003-10-01

181

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

182

Growth atmosphere dependence of transport properties of NiO epitaxial thin films  

NASA Astrophysics Data System (ADS)

Recent possible applications in nonvolatile resistive switching memory devices renewed the interests in the transport properties of NiO. The variation on the conductivities of NiO films was reported to strongly affect the resistive switching phenomena. The conduction mechanism of NiO has been interpreted in terms of the bulk p-type conduction mechanism via Ni deficiencies (Ni1-?O). Here we investigate the growth atmosphere dependence on the transport properties of NiO thin films epitaxially grown on MgO (001) substrate. The conductivities of NiO thin films showed completely an opposite tendency compared to the bulk p-type conduction mechanism. Microstructural analysis demonstrates that the conductivity of low temperature grown NiO thin films strongly correlates with tailing the band edge via the deterioration of entire film crystallinity rather than the grain boundaries including second phases.

Oka, Keisuke; Yanagida, Takeshi; Nagashima, Kazuki; Tanaka, Hidekazu; Kawai, Tomoji

2008-07-01

183

Kinesin-1-syntaphilin coupling mediates activity-dependent regulation of axonal mitochondrial transport.  

PubMed

Axonal mitochondria are recruited to synaptic terminals in response to neuronal activity, but the mechanisms underlying activity-dependent regulation of mitochondrial transport are largely unknown. In this paper, using genetic mouse model combined with live imaging, we demonstrate that syntaphilin (SNPH) mediates the activity-dependent immobilization of axonal mitochondria through binding to KIF5. In vitro analysis showed that the KIF5-SNPH coupling inhibited the motor adenosine triphosphatase. Neuronal activity further recruited SNPH to axonal mitochondria. This motor-docking interplay was induced by Ca(2+) and synaptic activity and was necessary to establish an appropriate balance between motile and stationary axonal mitochondria. Deleting snph abolished the activity-dependent immobilization of axonal mitochondria. We propose an "Engine-Switch and Brake" model, in which SNPH acts both as an engine off switch by sensing mitochondrial Rho guanosine triphosphatase-Ca(2+) and as a brake by anchoring mitochondria to the microtubule track. Altogether, our study provides new mechanistic insight into the molecular interplay between motor and docking proteins, which arrests axonal mitochondrial transport in response to changes in neuronal activity. PMID:23857772

Chen, Yanmin; Sheng, Zu-Hang

2013-07-22

184

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

SciTech Connect

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

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

2014-01-01

185

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

NASA Astrophysics Data System (ADS)

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

Pigarov, A. Yu.; Krasheninnikov, S. I.; Rognlien, T. D.; Hollmann, E. M.; Lasnier, C. J.; Unterberg, E.

2014-06-01

186

The AMOS (Azimuthal Mode Simulator) code  

SciTech Connect

AMOS is a newly developed computer code that is finding application in the design of accelerator cavities. The program simulates the temporal evolution of electromagnetic fields in rotationally symmetric structures. An explicit Fourier series expansion is assumed in the azimuthal coordinate, which allows different multipole modes to be simulated independently. Nonuniform electrical properties (epsilon, ..mu.., sigma) are permitted, and both impedance and radiation boundary conditions are available. A geometric editor (DRAGON) allows for simple and rapid development/modification of models, and a direct CAD system-DRAGON data link is being used to facilitate the study of existing and developmental linac accelerator cells. A wakefield postprocessor (ANDY) allows the calculation of wake potentials, cavity impedances, etc., from AMOS simulation data. Code verification has consisted of comparisons with exact and approximate analytic results for simple geometries. 6 refs., 3 figs.

DeFord, J.F.; Craig, G.D.; McLeod, R.

1989-03-10

187

Neutral lines and azimuthal 'transport' of solar energetic particles  

NASA Astrophysics Data System (ADS)

The study examines properties of solar energetic particle (SEP) events observed by both Helios spacecraft in the time period March 1976 to March 1980, in particular, variations of the intensity time profiles with angular distance between the flare and the observer's magnetic footpoint. Emphasis is placed on the neutral lines of the large-scale coronal magnetic field. For individual events, it is shown that sector boundaries can have a strong influence on intensities and time scales of SEP events. Variations of onset and maximum times as well as maximum intensities with angular distance between the flare and the observer's magnetic footpoint for 39 SEP events are discussed. It is found that particles can be observed on both sides of sector boundaries during both impulsive and gradual events. The onset times of about 0.5-MeV electrons can be ordered by the occurrence of sector boundaries.

Kallenrode, May-Britt

1993-04-01

188

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. PMID:21702047

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

2011-01-01

189

Variable-range hopping transport: crossovers from temperature dependence to electric field dependence in disordered carbon materials  

NASA Astrophysics Data System (ADS)

Variable-range hopping (VRH) is an important conduction mechanism in disordered conductors. One example of such a disordered conductor is reduced graphene oxide in which VRH dominates the temperature dependence of electronic conduction. Electronic transport is generally by electric field-assisted, thermally-driven VRH, following the theory of Mott, and Pollak and Riess. However, with the increase of electric field and decrease of temperature, we identify a surprisingly smooth crossover to solely field-driven VRH described by the theory of Shklovskii. We give the analytic expression for the crossover field E_C as a function of temperature and coefficients from thermally-driven and field-driven VRH. Besides reduced graphene oxide, we show in this work that our crossover scenario can also account for the experimentally measured conductivity data of three-dimensional (3D) carbon networks as well as that of quasi-1D highly-doped conducting polymers, illustrating the wide validity of our proposed physical scenario. Our crossover scenario has the advantage of combining two distinct regimes of VRH conduction yet remaining within the currently established theoretical framework.

Cheah, Chun Y.; Kaiser, Alan B.

2014-04-01

190

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

NASA Astrophysics Data System (ADS)

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

Aplin, Carol S.

191

NHERF1 Regulation of PTH-dependent Bimodal Pi Transport in Osteoblasts  

PubMed Central

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

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

2012-01-01

192

Geometric dependence of Nb-Bi2Te3-Nb topological Josephson junction transport parameters  

NASA Astrophysics Data System (ADS)

Superconductor-topological insulator-superconductor Josephson junctions have been fabricated in order to study the width dependence of the critical current, normal state resistance and flux periodicity of the critical current modulation in an external field. Previous literature reports suggest anomalous scaling in topological junctions due to the presence of Majorana bound states. However, for most realized devices, one would expect that trivial 2\\pi -periodic Andreev levels dominate transport. We also observe anomalous scaling behaviour of junction parameters, but the scaling can be well explained by mere geometric effects, such as the parallel bulk conductivity shunt and flux focusing.

Molenaar, C. G.; Leusink, D. P.; Wang, X. L.; Brinkman, A.

2014-10-01

193

Defect-concentration dependence of the charge-density-wave transport in tetrathiafulvalene tetracyanoquinodimethane  

NASA Astrophysics Data System (ADS)

The effect of electron-irradiation-induced defects on the non-Ohmic dc conductivity of tetrathiafulvalene tetracyanoquinodimethane (TTF-TCNQ) has been studied. The threshold field (ET) for non-Ohmic transport increases linearly with the defect concentration. This impurity study lends strong support to the explanation of the nonlinear conductivity in TTF-TCNQ by the depinning of the charge-density-wave condensate in strong electric fields. Both the nonlinear current and the Ohmic conductivity present a similar temperature dependence in the Peierls state.

Forro, L.; Lacoe, R.; Bouffard, S.; Jérome, D.

1987-04-01

194

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. PMID:17494091

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

2007-01-01

195

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

Microsoft Academic Search

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

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

2003-01-01

196

Spin-dependent electron transport in zinc- and manganese-doped adenine molecules  

NASA Astrophysics Data System (ADS)

The spin-dependent electron transport properties of zinc- and manganese-doped adenine molecules connected to zigzag graphene leads are studied in the zero bias regime using the non-equilibrium Green's function method. The conductance of the adenine molecule increased and became spin-dependent when a zinc or manganese atom was doped into the molecules. The effects of a transverse electric field on the spin-polarization of the transmitted electrons were investigated and the spin-polarization was controlled by changing the transverse electric field. Under the presence of a transverse electric field, both the zinc- and manganese-doped adenine molecules acted as spin-filters. The maximum spin-polarization of the manganese-doped adenine molecule was greater than the molecule doped with zinc.

Simchi, Hamidreza; Esmaeilzadeh, Mahdi; Mazidabadi, Hossein

2014-01-01

197

Effects of Jet Azimuthal Angular Distributions on Dijet Production Cross Sections in DIS  

E-print Network

A Monte Carlo study of the azimuthal angular distribution around the virtual boson-proton beam axis for dijet events in DIS at HERA is presented. In the presence of typical acceptance cuts on the jets in the laboratory frame, the azimuthal distribution is dominated by kinematic effects rather than the typical $\\cos\\phi$ and $\\cos 2\\phi$ dependence predicted by the QCD matrix elements. This implies that the $\\phi$ dependent part of the QCD matrix elements contributes even to the dijet production cross section. Neglecting this $\\phi$ dependence leads to an error of about 5-8\\% in the production cross section for typical acceptance cuts in the laboratory frame. We also present first NLO results on the $\\phi$-decorrelation of the jets through NLO effects.

Erwin Mirkes; Stefan Willfahrt

1997-08-04

198

Azimuth Variation in Microwave Backscatter over the Greenland Ice Sheet  

E-print Network

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

Long, David G.

199

Azimuth resolution acquisition through trajectory optimization for a SAR seeker  

Microsoft Academic Search

For a SAR seeker, how to acquire the best azimuth resolution within a fixed time is still a problem. As well known, the trajectory and the look angle have an effect on the azimuth resolution of imaging. This paper proposes a trajectory design and optimization method based on genetic algorithms. It builds the constraints of the missile at the flight

Zhao Hongzhong; Xie Huaying; Fu Qiang

2009-01-01

200

STATIC INITIAL AZIMUTH UPDATE METHOD IN LAND NAVIGATION SYSTEMS  

Microsoft Academic Search

The paper presents a method for the initial azimuth selection in Land Navigation Systems (LNS), applying the ZUPT (Zero-velocity UPdaTe) technique. This technique is understood as a correction of the initial setting achieve the best accuracy of the navigation. The case of the inaccurate initial azimuth during stopping of the vehicle (after short drive) in order to setting is considered.

Jacek Szymanowski

201

Azimuthally polarized surface plasmons as effective terahertz waveguides  

E-print Network

Azimuthally polarized surface plasmons as effective terahertz waveguides Qing Cao and Jürgen Jahns to the propagation of an azimuthally polarized surface plasmon along the wire. Some related aspects.6680) Surface plasmon, (230.7370) Waveguides; (260.3910) Metal, optics of. References and links 1. D. M

Jahns, Jürgen

202

Time dependent discrete ordinates neutron transport using distribution iteration in XYZ geometry  

NASA Astrophysics Data System (ADS)

The distribution iteration (DI) algorithm, developed by Wager [32] and Prins [28], for solving the Boltzmann Transport Equation (BTE) has proven, with further development, to be a robust alternative to von Neumann iteration on the scattering source, aka source iteration (SI). Previous work with DI was based on the time-independent form of the transport equation. In this research, the DI algorithm was (1) Improved to provide faster, more efficient, robust convergence; (2) Extended to XYZ geometry; (3) Extended to Multigroup Energy treatment; (4) Extended to solve the time-dependent form of the Boltzmann Transport Equation. The discrete ordinates equations for approximating the BTE have been solved using SI since the discrete ordinates method was developed at Los Alamos Scientific Laboratory by 1953. However, SI is often inefficient by itself and requires an accelerator in order to produce results efficiently and reliably. The acceleration schemes that are in use in production codes are Diffusion Synthetic Acceleration (DSA) and Transport Synthetic Acceleration (TSA). DSA is ineffective for some problems, and cannot be extended to high-performance spatial quadratures. TSA is less effective than DSA and fails for some problems. Krylov acceleration has been explored in recent years, but has many parameters that require problem-dependent tuning for efficiency and effectiveness. The DI algorithm is an alternative to source iteration that, in our testing, does not require an accelerator. I developed a formal verification plan and executed it to verify the results produced by my code that implemented DI with the above features. A new, matrix albedo, boundary condition treatment was developed and implemented so that infinite-medium benchmarks could be included in the verification test suite. The DI algorithm was modified for parallel efficiency and the prior instability of the refinement sweep was corrected. The testing revealed that DI performed as well or faster than source iteration with DSA and that DI continued to work where DSA failed. Performance did degrade when the diamond-difference (without fixup) spatial quadrature was used. Because diamond-difference is a non-positive spatial quadrature, it can produce nonphysical negative fluxes, particularly in higher dimensions. I developed a new fixup scheme to accommodate the negative fluxes, but it did not improve performance in XYZ geometry when the scattering ratio was near unity. My DI algorithm successfully solves the time-dependent form of the BTE using the semi-implicit method implemented by PARTISN. The agreement between DI and PARTISN was excellent. With these improvements and tests, DI is ready for use as a general replacement for von Neumann iteration on the scattering source.

Dishaw, James R.

203

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

NASA Astrophysics Data System (ADS)

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.

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

2011-04-01

204

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

NASA Astrophysics Data System (ADS)

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

Wei, Hsuang-Ping

205

A nitrogen-dependent switch in the high affinity ammonium transport in Medicago truncatula.  

PubMed

Ammonium transporters (AMTs) are crucial for the high affinity primary uptake and translocation of ammonium in plants. In the model legume Medicago truncatula, the genomic set of AMT-type ammonium transporters comprises eight members. Only four genes were abundantly expressed in young seedlings, both in roots and shoots. While the expression of all AMTs in the shoot was not affected by the nitrogen availability, the dominating MtAMT1;1 gene was repressed by nitrogen in roots, despite that cellular nitrogen concentrations were far above deficiency levels. A contrasting de-repression by nitrogen was observed for MtAMT1;4 and MtAMT2;1, which were both expressed at intermediate level. Weak expression was found for MtAMT1;2 and MtAMT2;3, while the other AMTs were not detected in young seedlings. When expressed from their endogenous promoters, translational fusion proteins of MtAMT1;1 and MtAMT2;1 with green fluorescent protein were co-localized in the plasma membrane of rhizodermal cells, but also detected in cortical root layers. Both transporter proteins similarly functionally complemented a yeast strain that is deficient in high affinity ammonium transport, both at acidic and neutral pH. The uptake into yeast mediated by these transporters saturated with Km AMT1;1 = 89 µM and Km AMT2;1 = 123 µM, respectively. When expressed in oocytes, MtAMT1;1 mediated much larger (15)N-ammonium uptake than MtAMT2;1, but NH4 (+) currents were only recorded for MtAMT1;1. These currents saturated with a voltage-dependent Km = 90 µM at -80 mV. The cellular localization and regulation of the AMTs suggests that MtAMT1;1 encodes the major high affinity ammonium transporter gene in low nitrogen grown young M. truncatula roots and despite the similar localization and substrate affinity, MtAMT2;1 appears functionally distinct and more important at higher nitrogen supply. PMID:25164101

Straub, Daniel; Ludewig, Uwe; Neuhäuser, Benjamin

2014-11-01

206

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

207

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

208

The effects of anandamide transport inhibitor AM404 on voltage-dependent calcium channels.  

PubMed

The effects of anandamide transport inhibitor AM404 were investigated on depolarization-induced 45Ca2+ fluxes in transverse tubule membrane vesicles from rabbit skeletal muscle and on Ba2+ currents through L-type voltage-dependent Ca2+ channels in rat myotubes. AM404, at the concentration of 3 microM and higher, caused a significant inhibition of 45Ca2+ fluxes. Radioligand binding studies indicated that the specific binding of [3H]Isradipine to transverse tubule membranes was also inhibited significantly by AM404. In controls and in presence of 10 microM AM404, B(max) values were 51+/-6 and 27+/-5 pM/mg, and KD values were 236+/-43 and 220+/-37 pM, respectively. Inhibitory effects of AEA and arachidonic acid on 45Ca2+ flux and [3H]Isradipine binding reported in earlier studies, were also enhanced significantly in the presence of AM404. In the presence of VDM11 (1 microM), another anandamide transport inhibitor, AM404 continued to inhibit 45Ca2+ fluxes and [3H]Isradipine binding. In rat myotubes, Ca2+ currents through L-type Ca2+ channels recorded in whole-cell configuration of patch clamp technique were inhibited by AM404 in a concentration-dependent manner with an IC50 value of 3.2 microM. In conclusion, results indicate that AM404 inhibits directly the function of L-type voltage-dependent Ca2+ channels in mammalian skeletal muscles. PMID:20171208

Alptekin, Alp; Galadari, Sehammuddin; Shuba, Yaroslav; Petroianu, Georg; Oz, Murat

2010-05-25

209

Hyperbolic theory for pH-dependent adsorption in reactive transport in porous media  

NASA Astrophysics Data System (ADS)

We use the hyperbolic theory of conservation laws to analyze the transport of strontium (Sr2+) through a porous medium with surface complexation. An hydrophilic iron-oxide surface was considered where Sr2+ and hydrogen (H+) compete for the same site leading to competitive adsorption described by an pH-dependent Langmuir isotherm. Despite the importance of pH-dependent adsorption in environmental applications, the basic structure of the displacement has received little attention. In reactive transport problems with pH-dependent adsorption, one of the conservation laws is for the total hydrogen (cHtot = cH+-cOH-) in the system, also called the acidity. The presence of this equation gives rise to additional nonlinearity in the problems that distinguishes them from other competitive sorption problems where hydrogen is not involved. We analyze a 1D reactive transport model with an incompressible fluid containing H+, Sr2+, sodium (Na+), and chlorine (Cl-) flowing through a reactive porous media made of goethite. Under the assumption of overall charge balance and of only advection for Na+ and Cl-, the mathematical problem reduces to a strictly hyperbolic 3x3 system of partial dierential equations (PDEs) for cHtot, Sr2+ (cSr2+), and effective anions (ca = cCl--cNa+) which are coupled by the adsorption isotherms for H+ and Sr2+ and have the non-linearity in the accumulation terms. One characteristic field is linearly degenerate while the other two are non-genuinely nonlinear due to inflection loci in both isotherms. We derived the complete set of analytical solutions to the Riemann problem (constant initial and injected states) and described the characteristic waves that may arise, concluding that only nine combinations of a contact discontinuity with rarefactions, shocks, shock-rarefactions are possible. The composite shock-rarefaction waves arise from the inflection loci in the isotherms and are absent in classic competitive Langmuir sorption. The inflection loci divide the composition space into two distinct high and low pH regions with distinct composition paths. The existence of a detached branch of the Hugoniot-locus is essential to the construction of composite waves that form when the left and right states are in distinct regions of the composition space. Highly resolved numerical solutions at large Peclet numbers show excellent agreement with the analytical solutions in the hyperbolic limit except under certain conditions when a pulse of Sr2+ and one of H+ arise ahead of the cor- responding retarded front and travel at the average fluid velocity. These conditions define the necessary conditions for the occurrence of the non-classical reactive transport which is not limited to only the Sr2+ front as observed in the earlier works [1,2] but it involves also the H+ front. These results raise important questions regarding the prediction of the migration of toxic compounds in the subsurface and pose also theoretical questions about the convergence of the vanishing diffusion solution to the hyperbolic limit, the stability of shock layers in reactive transport, and the role of the Riemann problem as an intermediate asymptotic solution for a wider range of problems. 1. Prigiobbe, V., Hesse, M., Bryant, S. L. (2012) Transport Porous Med 93 127-145. 2. Prigiobbe, V., Hesse, M., Bryant, S. L. (2012) accepted for publication in Geophys Res. Lett.

Prigiobbe, V.; Hesse, M. A.; Bryant, S. L.

2012-12-01

210

Transmembrane glucose transport in skeletal muscle of patients with non-insulin-dependent diabetes.  

PubMed Central

Insulin resistance for glucose metabolism in skeletal muscle is a key feature in non-insulin-dependent diabetes mellitus (NIDDM). Which cellular effectors of glucose metabolism are involved is still unknown. We investigated whether transmembrane glucose transport in vivo is impaired in skeletal muscle in nonobese NIDDM patients. We performed euglycemic insulin clamp studies in combination with the forearm balance technique (brachial artery and deep forearm vein catheterization) in six nonobese NIDDM patients and five age- and weight-matched controls. Unlabeled D-mannitol (a nontransportable molecule) and radioactive 3-O-methyl-D-glucose (the reference molecular probe to assess glucose transport activity) were simultaneously injected into the brachial artery, and the washout curves were measured in the deep venous effluent blood. In vivo transmembrane transport of 3-O-methyl-D-glucose in forearm muscle was determined by computerized analysis of the washout curves. At similar steady-state plasma concentrations of insulin (approximately 500 pmol/liter) and glucose (approximately 5.15 mmol/liter), transmembrane inward transport of 3-O-methyl-D-glucose in skeletal muscle was markedly reduced in the NIDDM patients (6.5 x 10(-2) +/- 0.56 x 10(-2).min-1) compared with controls (12.5 x 10(-2) +/- 1.5 x 10(-2).min-1, P < 0.005). Mean glucose uptake was also reduced in the diabetics both at the whole body level (9.25 +/- 1.84 vs. 28.3 +/- 2.44 mumol/min per kg, P < 0.02) and in the forearm tissues (5.84 +/- 1.51 vs. 37.5 +/- 7.95 mumol/min per kg, P < 0.02). When the latter rates were extrapolated to the whole body level, skeletal muscle accounted for approximately 80% of the defect in insulin action seen in NIDDM patients. We conclude that transmembrane glucose transport, when assessed in vivo in skeletal muscle, is insensitive to insulin in nonobese NIDDM patients, and plays a major role in determining whole body insulin resistance. Images PMID:8326013

Bonadonna, R C; Del Prato, S; Saccomani, M P; Bonora, E; Gulli, G; Ferrannini, E; Bier, D; Cobelli, C; DeFronzo, R A

1993-01-01

211

Spin-dependent transport in elemental and compound semiconductors and nanostructures  

NASA Astrophysics Data System (ADS)

The results obtained on spin-dependent processes via electrically detected magnetic resonance (EDMR), capacitance-detected magnetic resonance (CDMR) and noise-detected magnetic resonance (NDMR) in a variety of different semiconductor materials, devices and nanostructures are reviewed. Similar to optically detected magnetic resonance (ODMR), these detection methods are significantly more sensitive for the detection of paramagnetic states and defects than conventional electron spin resonance (ESR) and can be applied also to semiconductors with an indirect band gap. Using GaAs/AlGaAs-heterostructures and thin films of amorphous hydrogenated silicon (a-Si:H) as examples, the physics of spin-dependent recombination and its detection via spin-dependent photoconductivity is briefly recapitulated. EDMR on pn-diodes from GaP, GaAsP and group-III nitrides, resonant spin-spin scattering in strained Si/SiGe heterostructures, new hysteresis effects in the longitudinal magneto-transport through two-dimensional electron gases and edge-magneto plasmons in different III-V heterostructures are discussed. Various aspects of ferromagnetic III-V semiconductors are investigated, including doping of GaN with Mn, inhomogeneous magnetization of GaMnAs and control of ferromagnetism in semiconductors via hydrogen. Finally, preliminary EDMR experiments on the detection of single paramagnetic defects in MOSFETs via random telegraph noise are presented.

Brandt, M. S.; Goennenwein, S. T. B.; Graf, T.; Huebl, H.; Lauterbach, S.; Stutzmann, M.

2004-07-01

212

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

213

Azimuth estimates by human subjects under free-field and headphone conditions.  

PubMed

Estimates of sound source directions in the horizontal plane (azimuth) were made by human subjects under acoustic free-field (loudspeaker) and dichotic stimulus conditions (headphones). The functional relationship between the binaural cues, interaural time and intensity differences (ITDs and IIDs) and azimuth angle approximately follow a quarter of a full sine wave between 0 degrees straight ahead and the maximum at 90 degrees for ITDs and, depending on frequency for IIDs, at 60-90 degrees lateral (frontal quadrant). Under free-field conditions, these physically determined, interaural difference cues are correctly translated into azimuth angles by all listeners: estimated angles correspond to presented sound directions. In contrast, when providing dichotic stimuli containing ITDs/IIDs, so that sounds come from virtual azimuth angles, only 8% of the listeners estimated according to the expected transfer function of a quarter of a sine wave. However, about 60% of the listeners ranged azimuth directly proportionally to the binaural differences introduced, systematically overestimating virtual angles by up to 20 degrees. The remaining 32% of the listeners systematically overestimated virtual small and midrange sound directions even more. Virtual 40 degrees (corresponding to 12- to 14-dB and/or 450- to 550-microseconds differences) was often estimated as almost 90 degrees. Without corrective feedback, a reduction of the systematic errors was never observed. Central neural mechanisms and conceptual strategies to accomplish the expected transfer from virtual back to free-field directions are proposed to explain the large systematic overestimates: in contrast to our lifelong 'free-acoustic field' experience, we are unable, under dichotic conditions (hence in the absence of complete pinna cues and possibly room acoustics), to use the either innate or, more likely, acquired quarter of a sine interaural difference function necessary to accomplish the correct transfer. PMID:8179519

Schlegel, P A

1994-01-01

214

Azimuthal anisotropy in Au plus Au collisions at root S-NN=200 GeV  

E-print Network

strongly interacting quark gluon plasma phase [2?4]. At larger transverse momenta, measurements of azimuthal anisotropy are also relevant to the observation of jet quenching [5,6]. Given the current debate around these interpretations, we summarize STAR... scatterings. Calculations based on perturbative QCD predict that high-energy partons traversing nuclear matter lose energy through induced gluon radiation [36]. Energy loss (jet quenching) is expected to depend strongly on the color charge density...

Adams, J.; Aggarwal, MM; Ahammed, Z.; Amonett, J.; Anderson, BD; Arkhipkin, D.; Averichev, GS; Badyal, SK; Bai, Y.; Balewski, J.; Barannikova, O.; Barnby, LS; Baudot, J.; Bekele, S.; Belaga, VV; Bellwied, R.; Berger, J.; Bezverkhny, BI; Bharadwaj, S.; Bhasin, A.; Bhati, AK; Bhatia, VS; Bichsel, H.; Bielcik, J.; Bielcikova, J.; Billmeier, A.; Bland, LC; Blyth, CO; Bonner, BE; Botje, M.; Boucham, A.; Brandin, AV; Bravar, A.; Bystersky, M.; Cadman, RV; Cai, XZ; Caines, H.; Sanchez, MCD; Castillo, J.; Catu, O.; Cebra, D.; Chajecki, Z.; Chaloupka, P.; Chattopadhyay, S.; Chen, HF; Chen, Y.; Cheng, J.; Cherney, M.; Chikanian, A.; Christie, W.; Coffin, JP; Cormier, TM; Cramer, JG; Crawford, HJ; Das, D.; Das, S.; de Moura, MM; Derevschikov, AA; Didenko, L.; Dietel, T.; Dogra, SM; Dong, WJ; Dong, X.; Draper, JE; Du, F.; Dubey, AK; Dunin, VB; Dunlop, JC; Mazumdar, MRD; Eckardt, V.; Edwards, WR; Efimov, LG; Emelianov, V.; Engelage, J.; Eppley, G.; Erazmus, B.; Estienne, M.; Fachini, P.; Faivre, J.; Fatemi, R.; Fedorisin, J.; Filimonov, K.; Filip, P.; Finch, E.; Fine, V.; Fisyak, Y.; Fomenko, K.; Fu, J.; Gagliardi, Carl A.; Gaillard, L.; Gans, J.; Ganti, MS; Gaudichet, L.; Guerts, F.; Ghazikhanian, V.; Ghosh, P.; Gonzalez, JE; Grachov, O.; Grebenyuk, O.; Grosnick, D.; Guertin, SM; Guo, Y.; Gupta, A.; Gutierrez, TD; Hallman, TJ; Hamed, A.; Hardtke, D.; Harris, JW; Heinz, M.; Henry, TW; Hepplemann, S.; Hippolyte, B.; Hirsch, A.; Hjort, E.; Hoffmann, GW; Huang, HZ; Huang, SL; Hughes, EW; Humanic, TJ; Igo, G.; Ishihara, A.; Jacobs, P.; Jacobs, WW; Janik, M.; Jiang, H.; Jones, PG; Judd, EG; Kabana, S.; Kang, K.; Kaplan, M.; Keane, D.; Khodyrev, VY; Kiryluk, J.; Kisiel, A.; Kislov, EM; Klay, J.; Klein, SR; Koetke, DD; Kollegger, T.; Kopytine, M.; Kotchenda, L.; Kramer, M.; Kravtsov, P.; Kravtsov, VI; Krueger, K.; Kuhn, C.; Kulikov, AI; Kumar, A.; Kutuev, RK; Kuznetsov, AA; Lamont, MAC; Landgraf, JM; Lange, S.; Laue, F.; Lauret, J.; Lebedev, A.; Lednicky, R.; Lehocka, S.; LeVine, MJ; Li, C.; Li, Q.; Li, Y.; Lin, G.; Lindenbaum, SJ; Lisa, MA; Liu, F.; Liu, L.; Liu, QJ; Liu, Z.; Ljubicic, T.; Llope, WJ; Long, H.; Langacre, RS; Lopez-Noriega, M.; Love, WA; Lu, Y.; Ludlam, T.; Lynn, D.; Ma, GL; Ma, JG; Ma, YG; Magestro, D.; Mahajan, S.; Mahapatra, DP; Majka, R.; Mangotra, LK; Manweiler, R.; Margetis, S.; Markert, C.; Martin, L.; Marx, JN; Matis, HS; Matulenko, YA; McClain, CJ; McShane, TS; Meissner, F.; Melnick, Y.; Meschanin, A.; Miller, ML; Minaev, NG; Mironov, C.; Mischke, A.; Mishra, DK; Mitchell, J.; Mohanty, B.; Molnar, L.; Moore, CF; Morozov, DA; Munhoz, MG; Nandi, BK; Nayak, SK; Nayak, TK; Nelson, JM; Netrakanti, PK; Nikitin, VA; Nogach, LV; Nurushev, SB; Odyniec, G.; Ogawa, A.; Okorokov, V.; Oldenburg, M.; Olson, D.; Pal, SK; Panebratsev, Y.; Panitkin, SY; Pavlinov, AI; Pawlak, T.; Peitzmann, T.; Perevoztchikov, V.; Perkins, C.; Peryt, W.; Petrov, VA; Phatak, SC; Picha, R.; Planinic, M.; Pluta, J.; Porile, N.; Porter, J.; Poskanzer, AM; Potekhin, M.; Potrebenikova, E.; Potukuchi, BVKS; Prindle, D.; Pruneau, C.; Putschke, J.; Rakness, G.; Raniwala, R.; Raniwala, S.; Ravel, O.; Ray, RL; Razin, SV; Reichhold, D.; Reid, JG; Renault, G.; Retiere, F.; Ridiger, A.; Ritter, HG; Roberts, JB; Rogachevskiy, OV; Romero, JL; Rose, A.; Roy, C.; Ruan, L.; Sahoo, R.; Sakrejda, I.; Salur, S.; Sandweiss, J.; Sarsour, M.; Savin, I.; Sazhin, PS; Schambach, J.; Scharenberg, RP; Schmitz, N.; Schweda, K.; Seger, J.; Seyboth, P.; Shahaliev, E.; Shao, M.; Shao, W.; Sharma, M.; Shen, WQ; Shestermanov, KE; Shimanskiy, SS; Sichtermann, E.; Simon, F.; Singaraju, RN; Skoro, G.; Smirnov, N.; Snellings, R.; Sood, G.; Sorensen, P.; Sowinski, J.; Speltz, J.; Spinka, H. M.; Srivastava, B.; Stadnik, A.; Stanislaus, TDS; Stock, R.; Stolpovsky, A.; Strikhanov, M.; Stringfellow, B.; Suaide, AAP; Sugarbaker, E.; Suire, C.; Sumbera, M.; Surrow, B.; Symons, TJM; de Toledo, AS; Szarwas, P.; Tai, A.; Takahashi, J.; Tang, AH; Tarnowsky, T.; Thein, D.; Thomas, JH; Timoshenko, S.; Tokarev, M.; Trainor, TA; Trentalange, S.; Tribble, Robert E.; Tsai, OD; Ulery, J.; Ullrich, T.; Underwood, DG; Urkinbaev, A.; van Buren, G.; van Leeuwen, M.; Molen, AMV; Varma, R.; Vasilevski, IM; Vasiliev, AN; Vernet, R.; Vigdor, SE; Viyogi, YP; Vokal, S.; Voloshin, SA; Vznuzdaev, M.; Waggoner, WT; Wang, F.; Wang, G.; Wang, G.; Wang, XL; Wang, Y.; Wang, Y.; Wang, ZM; Ward, H.; Watson, JW; Webb, JC; Wells, R.; Westfall, GD; Wetzler, A.; Whitten, C.; Wieman, H.; Wissink, SW; Witt, R.; Wood, J.; Wu, J.; Xu, N.; Xu, Z.; Xu, ZZ; Yamamoto, E.; Yepes, P.; Yurevich, VI; Zanevsky, YV; Zhang, H.; Zhang, WM; Zhang, ZP; Zoulkarneev, R.; Zoulkarneeva, Y.; Zubarev, AN; Braem, A.; Davenport, M.; Cataldo, GD; Bari, DD; Martinengo, P.; Nappi, E.; Paic, G.; Posa, E.; Puiz, F.; Schyns, E.; Star Collaboration; STAR-RICH Collaboration.

2005-01-01

215

The dependence of H-mode energy confinement and transport on collisionality in NSTX  

NASA Astrophysics Data System (ADS)

Understanding the dependence of confinement 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 the 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 increase of normalized confinement with decreasing collisionality. Discharges with lithium conditioning discussed in the present study generally achieved lower collisionality, extending the accessible range of collisionality by a factor of two. 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 confinement time, BT?E, with decreasing collisionality when other dimensionless variables were held as fixed as possible. This increase of confinement 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 (ETG) 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.

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

2013-06-01

216

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

SciTech Connect

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

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

2012-05-15

217

Nonparaxial and paraxial focusing of azimuthal-variant vector beams.  

PubMed

Based on the vectorial Rayleigh-Sommerfeld formulas under the weak nonparaxial approximation, we investigate the propagation behavior of a lowest-order Laguerre-Gaussian beam with azimuthal-variant states of polarization. We present the analytical expressions for the radial, azimuthal, and longitudinal components of the electric field with an arbitrary integer topological charge m focused by a nonaperturing thin lens. We illustrate the three-dimensional optical intensities, energy flux distributions, beam waists, and focal shifts of the focused azimuthal-variant vector beams under the nonparaxial and paraxial approximations. PMID:23038320

Gu, Bing; Cui, Yiping

2012-07-30

218

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

2012-03-01

219

Spin dependent transport and spin transfer in nanoconstrictions and current confined nanomagnets  

NASA Astrophysics Data System (ADS)

In this thesis, I have employed point contact spectroscopy to determine the nature of electron transport across constrained domain walls in a ferromagnetic nanocontact and to uncover the relationship between ballisticity of electron transport and domain wall magnetoresistance. In the range of hole sizes studied (from 10 to 3 nm) the resulting magnetoresistance was found to be less than 0.5% and one that increases with decreasing contact size. I have used point contacts as local probes, to study the spin dependent transport across Ferromagnet/Normal Metal/Ferromagnet(FM/NM/FM) trilayers as well as the consequences of localized spin polarized current injection into a nano magnet on spin angular momentum transfer and high frequency magnetization dynamics. I have demonstrated that absolute values for spin transfer switching critical currents are reduced in this new geometry as compared to uniform current injection. I have also performed micromagnetic simulations to determine the evolution of magnetization under the application of magnetic fields and currents to gain more insights into experimental results. I have used Scanning Transmission Electron Microscopy (STEM), X-Ray Photoemission Spectroscopy (XPS) and Electron Energy Loss Spectroscopy (EELS) techniques to characterize the interfacial mixing and oxygen diffusion in the metallic multilayers of interest. I have shown that the Ta/CuOx bilayer structure provides a smooth substrate by improving interfacial roughness due to grain boundary diffusion of oxygen and reaction with Ta that fills in the grain boundary gaps in Cu. Analysis of the Py/AlOx interface proved a strong oxidation passivation on the Py surface by Al coating accompanied by Fe segregation into the alumina. I have utilized the characterization results to design a new nanomagnet whose sidewalls are protected from adventitious sidewall oxide layers and yields improved device performance. The oxide layers that naturally develop at the sidewalls of Py nanomagnets cause an enhancement in magnetic damping especially for temperatures below the blocking temperature of the AFM layer (?40K). Studies with pillars protected by Al coating and ones with more NiO coating (˜2.5 nm) shed light onto the role of surface oxides in determining temperature dependent behaviour of both spin torque and field driven switching characteristics.

Ozatay, Ozhan

220

Cytokine-dependent regulation of hepatic organic anion transporter gene transactivators in mouse liver.  

PubMed

Proinflammatory cytokines such as TNF-alpha and IL-1beta lead to downregulation of hepatic organic anion transporters in cholestasis. This adapted response is transcriptionally mediated by nuclear hormone receptors and liver-specific transcription factors. Because little is known in vivo about cytokine-dependent regulatory events, mice were treated with either TNF-alpha or IL-1beta for up to 16 h. Transporter mRNA expression was determined by Northern blot analysis, nuclear activity, and protein-expression of transactivators by EMSA and Western blotting. TNF-alpha induces a sustained decrease in Ntcp, Oatp1/Oatp1a1, and Bsep mRNA expression but exerts only transient [multidrug resistance-associated protein 2 (Mrp2)] or no effects (Mrp3) on Mrps. In addition to Ntcp and Oatp1/Oatp1a1, IL-1beta also downregulates Bsep, Mrp2, and Mrp3 mRNAs to some extent. To study transcriptional regulation, Ntcp and Bsep promoters were first cloned from mice revealing a new distal Ntcp hepatocyte nuclear factor 1 (HNF-1) element but otherwise show a conserved localization to known rat regulatory elements. Changes in transporter-expression are preceeded by a reduction in binding activities at IR-1, ER-8, DR-5, and HNF-1alpha sites after 4 h by either cytokine, which remained more sustained by TNF-alpha in the case of nuclear receptors. Nuclear protein levels of retinoid X receptor (RXR)-alpha are significantly decreased by TNF-alpha but only transiently affected by IL-1beta. Minor reductions of retinoic acid receptor, farnesoid X receptor, pregnane X receptor, and constitutive androstane receptor nuclear proteins are restricted to 4 h after cytokine application and paralleled by a decrease in mRNA levels. Basolateral and canalicular transporter systems are downregulated by both cytokines, TNF-alpha and IL-1beta. Activity of HNF-1alpha as regulator of mNtcp is suppressed by both cytokines. Decreased binding activities of nuclear receptor heterodimers may be explained by a reduction of the ubiquitous heterodimerization partner RXR-alpha. PMID:15860642

Geier, Andreas; Dietrich, Christoph G; Voigt, Sebastian; Ananthanarayanan, Meenakshisundaram; Lammert, Frank; Schmitz, Anne; Trauner, Michael; Wasmuth, Hermann E; Boraschi, Diana; Balasubramaniyan, Natarajan; Suchy, Frederick J; Matern, Siegfried; Gartung, Carsten

2005-11-01

221

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

2013-08-15

222

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

PubMed Central

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

2013-01-01

223

Three Ubiquitination Sites of Organic Anion Transporter-1 Synergistically Mediate Protein Kinase C-Dependent Endocytosis of the Transporter  

PubMed Central

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

2013-01-01

224

Azimuthal Asymmetry of Prompt Photons in Nuclear Collisions  

E-print Network

The azimuthal elliptic asymmetry v2 observed in heavy ion collisions, is usually associated with properties of the medium created in the final state. We compute the azimuthal asymmetry which is due to multiple interactions of partons at the initial stage of nuclear collisions, and which is also present in $pA$ collisions. In our approach the main source of azimuthal asymmetry is the combination of parton multiple interactions with the steep variation of the nuclear density at the edge of nuclei. We apply the light-cone dipole formalism to compute the azimuthal asymmetry of prompt photons yield from parton-nucleus, proton-nucleus and nucleus-nucleus collisions at the RHIC energy.

B. Z. Kopeliovich; A. H. Rezaeian; Ivan Schmidt

2007-12-17

225

Azimuthal anisotropy: transition from hydrodynamic flow to jet suppression  

E-print Network

Measured 2nd and 4th azimuthal anisotropy coefficients v_{2,4}(N_{part}), p_T) are scaled with the initial eccentricity \\varepsilon_{2,4}(N_{part}) of the collision zone and studied as a function of the number of participants N_{part} and the transverse momenta p_T. Scaling violations are observed for $p_T \\alt 3$ GeV/c, consistent with a $p_T^2$ dependence of viscous corrections and a linear increase of the relaxation time with $p_T$. 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 $p_T \\agt 3$ GeV/c, suggesting a breakdown of the hydrodynamic ansatz and the onset of a change from flow-driven to suppression-driven anisotropy.

Roy A. Lacey; A. Taranenko; R. Wei; N. N. Ajitanand; J. M. Alexander; J. Jia; R. Pak; K. Dusling; Dirk H. Rischke; D. Teaney

2010-05-27

226

Carbohydrate kinase (RhaK)-dependent ABC transport of rhamnose in Rhizobium leguminosarum demonstrates genetic separation of kinase and transport activities.  

PubMed

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

Rivers, Damien; Oresnik, Ivan J

2013-08-01

227

Measurement of Azimuthal Asymmetries in Inclusive Production of Hadron Pairs in e{sup +}e{sup -} Annihilation at Belle  

SciTech Connect

The Collins effect connects transverse quark spin with a measurable azimuthal dependence in the yield of hadronic fragments around the quark's momentum vector. Using two different reconstruction methods, we find evidence of statistically significant azimuthal asymmetries for charged pion pairs in e{sup +}e{sup -} annihilation at a center-of-mass energy of 10.52 GeV, which can be attributed to a transverse polarization of the primordial quarks. The measurement was performed using a sample of 79x10{sup 6} hadronic events collected with the Belle detector.

Seidl, R.; Hasuko, K.; Grosse Perdekamp, M.; Ogawa, A. [RIKEN BNL Research Center, Upton, New York 11973 (United States); Abe, K.; Hoshi, Y. [Tohoku Gakuin University, Tagajo (Japan); Adachi, I.; Dragic, J.; Gershon, T.; Hazumi, M.; Ishikawa, A.; Itoh, R.; Iwasaki, Y.; Katayama, N.; Kichimi, H.; Limosani, A.; Nakamura, I.; Nakao, M.; Nishida, S.; Ozaki, H. [High Energy Accelerator Research Organization (KEK), Tsukuba (Japan)] (and others)

2006-06-16

228

Control of Arabidopsis meristem development by thioredoxin-dependent regulation of intercellular transport  

Microsoft Academic Search

Cell-to-cell transport in plants occurs through cytoplasmic channels called ``plasmodesmata'' and is regulated by developmental and environmental factors. Callose deposition modulates plasmodesmal transport in vivo, but little is known about the mechanisms that regulate this process. Here we report a genetic approach to identify mutants affecting plasmodesmal transport. We isolated 5 mutants, named gfp arrested trafficking (gat), affected in GFP

Yoselin Benitez-Alfonso; Michelle Cilia; Adrianna San Roman; Carole Thomas; Andy Maule; Stephen Hearn; David Jackson

2009-01-01

229

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

E-print Network

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

Boyer, Edmond

230

Generation of azimuthally and radially polarized off-axis beams with an intracavity large-apex-angle axicon.  

PubMed

Depending on cavity configuration, a c-cut Nd:YVO4 laser by using a large-apex-angle axicon can execute azimuthally and radially polarized operations. A large-apex-angle axicon dominates and stabilizes the generation of the pattern, and expands the difference between the ordinary and extraordinary rays to generate off-axis cylindrical vector beams. When the cavity length is properly adjusted, the polarization of off-axis laser beams can exhibit a transition from azimuthal to radial polarization. The degree of polarizations can be up to 95.4% ± 2.6% and 94% ± 3.7% for azimuthally and radially polarized beams, respectively; and the slope efficiencies are approximately 20.5% for both polarized operations. Using two-pass-mode ray tracing, the ray generating mechanisms and divergent angles of their patterns were analyzed. PMID:23842390

Chang, Ken-Chia; Lin, Tyson; Wei, Ming-Dar

2013-07-01

231

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

232

Polymorphisms in the dopamine transporter gene (SLC6A3/DAT1) and alcohol dependence in humans: a systematic review.  

PubMed

Dopamine neurotransmission has been a key player in attempts to identify genetic factors involved in alcohol dependence. The dopamine transporter terminates dopaminergic neurotransmission, making the gene encoding the transporter (SLC6A3/DAT1) an attractive candidate in clinical studies on alcohol dependence. We conducted a systematic review of 18 studies examining associations between polymorphisms in DAT1 and alcohol dependence. The DAT1 variable number tandem repeat, the most frequent studied polymorphism in DAT1, did not show a direct association with alcohol dependence in general. Several, but not all, studies found that the DAT1 variable number tandem repeat (9-repeat allele) was associated with alcohol-withdrawal symptoms, such as seizures and delirium tremens. We discuss shortcomings, such as lack of power and disregarding moderating variables, as well as future challenges of gene association studies. PMID:19450132

van der Zwaluw, Carmen S; Engels, Rutger C M E; Buitelaar, Jan; Verkes, Robbert J; Franke, Barbara; Scholte, Ron H J

2009-05-01

233

Energy-dependent uptake of benzo[a]pyrene and its cytoskeleton-dependent intracellular transport by the telluric fungus Fusarium solani.  

PubMed

In screening indigenous soil filamentous fungi for polycyclic aromatic hydrocarbons (PAHs) degradation, an isolate of the Fusarium solani was found to incorporate benzo[a]pyrene (BaP) into fungal hyphae before degradation and mineralization. The mechanisms involved in BaP uptake and intracellular transport remain unresolved. To address this, the incorporation of two PAHs, BaP, and phenanthrene (PHE) were studied in this fungus. The fungus incorporated more BaP into cells than PHE, despite the 400-fold higher aqueous solubility of PHE compared with BaP, indicating that PAH incorporation is not based on a simple diffusion mechanism. To identify the mechanism of BaP incorporation and transport, microscopic studies were undertaken with the fluorescence probes Congo Red, BODIPY®493/503, and FM®4-64, targeting different cell compartments respectively fungal cell walls, lipids, and endocytosis. The metabolic inhibitor sodium azide at 100 mM totally blocked BaP incorporation into fungal cells indicating an energy-requirement for PAH uptake into the mycelium. Cytochalasins also inhibited BaP uptake by the fungus and probably its intracellular transport into fungal hyphae. The perfect co-localization of BaP and BODIPY reveals that lipid bodies constitute the intracellular storage sites of BaP in F. solani. Our results demonstrate an energy-dependent uptake of BaP and its cytoskeleton-dependent intracellular transport by F. solani. PMID:24271730

Fayeulle, Antoine; Veignie, Etienne; Slomianny, Christian; Dewailly, Etienne; Munch, Jean-Charles; Rafin, Catherine

2014-03-01

234

Parametric dependence of turbulent particle transport in high density electron heated FTU plasmas  

NASA Astrophysics Data System (ADS)

In this paper we present the result of a study carried out at the Frascati Tokamak Upgrade (FTU), on a set of full non-inductive current driven, electron heated, L-mode discharges aimed at investigating the parametric dependence of the electron density profile on the electron temperature and safety factor gradients as predicted by quasi-linear drift-turbulence transport theory. Experiments in FTU allow the extension of similar studies carried out on other tokamaks to plasmas with higher density and higher magnetic field. Magnetic shear and electron temperature gradients are found to drive opposite turbulent particle flows in the gradient region (0.3 < r/a <= 0.5), while inward thermo-diffusion alone is found in the plasma core (r/a <= 0.3). Density profiles at midradius appear to be controlled by a convective term proportional to the density and independent of the gradient of temperature and magnetic shear. A linear increase in density peaking versus effective collisionality is found, differing from the scaling observed in other FTU plasma regimes.

Romanelli, M.; Hoang, G. T.; Bourdelle, C.; Gormezano, C.; Giovannozzi, E.; Leigheb, M.; Marinucci, M.; Marocco, D.; Mazzotta, C.; Panaccione, L.; Pericoli, V.; Regnoli, G.; Tudisco, O.; FTU Team

2007-06-01

235

Modulation of Bacterial Type III Secretion System by a Spermidine Transporter Dependent Signaling Pathway  

PubMed Central

Background Many gram-negative bacterial pathogens employ Type III secretion systems (T3SS) to inject effector proteins into host cells in infectious processes. Methodology/Principal Findings By screening a transposon mutant library of P. aeruginosa, we found that mutation of spuDEFGH, which encode a major spermidine uptake system, abolished the expression of the exsCEBA operon that codes for key T3SS regulators under inducing conditions (low calcium). Whole genome microarray analysis revealed that inactivation of the spermidine uptake system significantly decreased the transcriptional expression of most, if not all, T3SS genes. Consistently, the spermidine uptake mutants showed decreased expression of the T3SS genes in responding to host cell extract and attenuated cytotoxicity. Furthermore, exogenous addition of spermidine to the wild type strain PAO1 enhanced the expression of exsCEBA and also the effector protein genes. Conclusion/Significance Cumulatively, these data have depicted a novel spermidine transporter-dependent signaling pathway, which appears to play an essential role in modulation of T3SS expression in P. aeruginosa. PMID:18074016

Zhou, Lian; Wang, Jing; Zhang, Lian-Hui

2007-01-01

236

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

E-print Network

Time-dependent helium gas puff experiments have been performed on the Mega Ampere Spherical Tokamak (MAST) during a two point plasma current scan in L-mode and a confinement scan at 900 kA. An evaluation of the He II spectrum line induced by charge exchange suggests anomalous rates of diffusion and inward convection in the outer regions of both L-mode plasmas. Similar rates of diffusion are found in the H-mode plasma, however these rates are consistent with neoclassical predictions. The anomalous inward pinch found in the core of L-mode plasmas is also not apparent in the H-mode core. Linear gyrokinetic simulations of one flux surface in L-mode using the gs2 and gkw codes find that equilibrium flow shear is sufficient to stabilise ITG modes, consistent with BES observations, and suggest that collisionless TEMs may dominate the anomalous helium particle transport. A quasilinear estimate of the dimensionless peaking factor associated with TEMs is in good agreement with experiment. Collisionless TEMs are more st...

Henderson, S S; Casson, F J; Dickinson, D; Fox, M F J; O'Mullane, M; Patel, A; Roach, C M; Summers, H P; Valovic, M

2014-01-01

237

Spin-dependent thermoelectric effects in transport through a nanoscopic junction involving a spin impurity  

NASA Astrophysics Data System (ADS)

Conventional and spin-related thermoelectric effects in transport through a magnetic tunnel junction with a large-spin impurity, such as a magnetic molecule or atom, embedded into the corresponding barrier are studied theoretically in the linear-response regime. The impurity is described by the giant spin Hamiltonian, with both uniaxial and transverse magnetic anisotropy taken into account. Owing to the presence of the transverse component of magnetic anisotropy, the spin of a tunneling electron can be reversed during scattering on the impurity, even in the low-temperature regime. This reversal appears due to the exchange interaction of tunneling electrons with the magnetic impurity. We calculate Seebeck and spin Seebeck coefficients, and analyze their dependence on various parameters of the spin impurity and tunnel junction. In addition, conventional and spin figures of merit as well as the electronic contribution to heat conductance are considered. We also show that pure spin current can be driven by a spin bias applied to the junction with spin impurity, even if no electron transfer between the electrodes can take place. The underlying mechanism employs single-electrode tunneling processes (electrode-spin exchange interaction) and the impurity as an intermediate reservoir of angular momentum.

Misiorny, Maciej; Barna?, Józef

2014-06-01

238

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

NASA Technical Reports Server (NTRS)

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

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

2004-01-01

239

Phosphoenolpyruvate-dependent phosphotransferase system enzyme III and plasmid-encoded sucrose transport in Escherichia coli K-12.  

PubMed Central

The phosphoenolpyruvate-dependent carbohydrate:phosphotransferase system enzyme IISCR, specific for and regulated by sucrose, was analyzed in derivatives of Escherichia coli K-12 carrying the sucrose plasmid pUR404. Enzyme IIScr, coded for by gene scrA of the plasmid, depended for its transport and phosphorylation activity directly on the phosphotransferase system enzyme IIIGlc, Scr, coded for by the chromosomal gene crr. PMID:7045081

Lengeler, J W; Mayer, R J; Schmid, K

1982-01-01

240

Evidence for high affinity binding-protein dependent transport systems in gram-positive bacteria and in Mycoplasma.  

PubMed Central

Gram-negative bacteria are surrounded by two membranes. In these bacteria, a class of high affinity transport systems for concentrating substrates from the medium into the cell, involves a binding protein located between the outer and inner membranes, in the periplasmic region. These 'periplasmic binding-proteins' are thought to bind the substrate in the vicinity of the inner membrane, and to transfer it to a complex of inner membrane proteins for concentration into the cytoplasm. We report evidence leading us to propose that a Gram-positive bacterium, Streptococcus pneumoniae, and a mycoplasma, Mycoplasma hyorhinis, which are surrounded by a single membrane and have therefore no periplasmic region, possess an equivalent to the high affinity periplasmic binding-protein dependent transport systems, i.e. extra-cytoplasmic binding lipoprotein dependent transport systems. The 'binding lipoproteins' would be maintained at proximity of the inner membrane by insertion of their N-terminal glyceride-cysteine into this membrane. Images PMID:3208757

Gilson, E; Alloing, G; Schmidt, T; Claverys, J P; Dudler, R; Hofnung, M

1988-01-01

241

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

Microsoft Academic Search

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

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

2006-01-01

242

The Role of Sodium-Dependent Glucose Transporter 1 and Glucose Transporter 2 in the Absorption of Cyanidin-3-O-?-Glucoside in Caco-2 Cells  

PubMed Central

Anthocyanins have multiple biological activities of benefit to human health. While a few studies have been conducted to evaluate the bioavailability of anthocyanins, the mechanisms of their absorption mechanism remain ill-defined. In the present study, we investigated the absorption mechanism of cyanidin-3-O-?-glucoside (Cy-3-G) in human intestinal epithelial (Caco-2) cells. Cy-3-G transport was assessed by measuring the absorptive and efflux direction. Inhibition studies were conducted using the pharmacological agents, phloridzin, an inhibitor of sodium-dependent glucose transporter 1 (SGLT1), or phloretin, an inhibitor of glucose transporter 2 (GLUT2). The results showed that phloridzin and phloretin significantly inhibited the absorption of Cy-3-G. In addition, Caco-2 cells transfected with small interfering RNA (siRNA) specific for SGLT1 or GLUT2 showed significantly decreased Cy-3-G absorption. These siRNA transfected cells also showed a significantly decreased rate of transport of Cy-3-G compared with the control group. These findings suggest that Cy-3-G absorption is dependent on the activities of SGLT1 and GLUT2 in the small intestine and that SGLT1 and GLUT2 could be a limiting step for the bioavailability of Cy-3-G. PMID:25314643

Zou, Tang-Bin; Feng, Dan; Song, Gang; Li, Hua-Wen; Tang, Huan-Wen; Ling, Wen-Hua

2014-01-01

243

Azimuthal polarization for Raman enhancement in capillary waveguides  

NASA Astrophysics Data System (ADS)

Hollow, metal-lined capillary waveguides have recently been utilized in spontaneous gas-Raman spectroscopy to improve signal strength and response time. The hollow waveguide is used to contain the sample gases, efficiently propagate a pump beam, and efficiently collect Raman scattering from those gases. Transmission losses in the waveguide may be reduced by using an azimuthally polarized pump beam instead of a linearly or radially polarized pump. This will lead to improved Raman signal strength, accuracy, and response time in waveguide-based Raman gas-composition sensors. A linearly polarized laser beam is azimuthally polarized using passive components including a spiral phase plate and an azimuthal-type linear analyzer element. Half-wave plates are then used to switch between the azimuthally polarized beam and the radially polarized beam with no change in input pump power. The collected Raman signal strength and laser throughput are improved when the azimuthally polarized pump is used. Optimization of the hollow waveguide Raman gas sensor is discussed with respect to incident pump polarization.

Mullen, Jessica C.; Buric, Michael P.; Chorpening, Benjamin T.; Woodruff, Steven D.

2013-11-01

244

Quality Control and Substrate-Dependent Downregulation of the Nutrient Transporter Fur4  

PubMed Central

Upon exposure to stress conditions, unfolded cell-surface nutrient transporters are rapidly internalized and degraded via the multivesicular body (MVB) pathway. Similarly, high concentrations of nutrients result in the downregulation of the corresponding transporters. Our studies using the yeast transporter Fur4 revealed that substrate-induced downregulation and quality control utilize a common mechanism. This mechanism is based on a conformation-sensing domain, termed LID (Loop Interaction Domain), that regulates site-specific ubiquitination (also known as degron). Conformational alterations in the transporter induced by unfolding or substrate binding are transmitted to the LID, rendering the degron accessible for ubiquitination by Rsp5. As a consequence, the transporter is rapidly degraded. We propose that the LID-degron system is a conserved, chaperone-independent mechanism responsible for conformation-induced downregulation of many cell-surface transporters under physiological and pathological conditions. PMID:23305501

Keener, Justin M.; Babst, Markus

2013-01-01

245

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

E-print Network

.e., DMT1 (17), hZIP1 (15), hZIP2 (14), and ZnT-1 (28), has provided new molecular and ge- netic tools revealed interesting pH effects on Zn2 transport mediated by either DMT1 (17, 35) or hZIP1 and hZIP2 (14, 15). DMT1 shows nonspecific divalent metal transport (most notably iron transport in the intestine

246

The dependence of exciton transport efficiency on spatial patterns of correlation within the spectral bath  

NASA Astrophysics Data System (ADS)

Spatial correlations in spectral bath motions have been proposed to explain long-lived coherence in exciton transport. Systems of interest, ranging from photosynthetic complexes to organic photovoltaics, contain inhomogeneous environments. We consider the possibility that the degree of spatial correlation varies throughout an exciton transport system. We model exciton transport in the Fenna-Matthews-Olson complex (FMO), a photosynthetic light-harvesting complex. Although it remains unclear whether significant spatial correlations exist in FMO, its very high exciton transport efficiency makes it an interesting case for studies of exciton transport. We also simulate a highly symmetric ten-site model system. We use an extension of the environment-assisted quantum transport model to simulate transport, allowing the spatial correlation function to vary throughout the system. We demonstrate both via analysis and via simulation that exciton transport efficiency is most sensitive to changes in correlation between the site coupled to the trap and its neighboring sites. This asymmetry in sensitivity is highly robust and appears irrespective of changes in parameters such as transition dipole orientations and initial conditions. Our results suggest that in the design of exciton transport systems, efforts to increase efficiency by controlling spatial correlation should be focused on the region near the site of exciton trapping.

Pelzer, Kenley M.; Fidler, Andrew F.; Griffin, Graham B.; Gray, Stephen K.; Engel, Gregory S.

2013-09-01

247

Many-electron transport in Aharonov-Bohm interferometers: A time-dependent density-functional study  

NASA Astrophysics Data System (ADS)

We apply time-dependent density-functional theory to study many-electron transport in Aharonov-Bohm interferometers in a non-equilibrium situation. The conductance properties in the system are complex and depend on the enclosed magnetic flux in the interferometer, the number of interacting electrons, and the mutual distance of the transport channels at the points of encounter. Generally, the electron-electron interactions do not suppress the visibility of Aharonov-Bohm oscillations if the interchannel distance — determined by the positioning of the incompressible strips through the external magnetic field - is optimized. However, the interactions also impose an interesting Aharonov-Bohm phase shift with channel distances below or above the optimal one. This effect is combined with suppressed oscillation amplitudes. We analyze these effects within different approximations for the exchange-correlation potential in time-dependent density-functional theory.

Salman, Aysevil; Kotimäki, Ville; S?dd?ki, Afif; Räsänen, Esa

2013-04-01

248

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

PubMed Central

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

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

2009-01-01

249

The Caenorhabditis elegans snf-11 Gene Encodes a Sodium-dependent GABA Transporter Required for Clearance of Synaptic GABA  

PubMed Central

Sodium-dependent neurotransmitter transporters participate in the clearance and/or recycling of neurotransmitters from synaptic clefts. The snf-11 gene in Caenorhabditis elegans encodes a protein of high similarity to mammalian GABA transporters (GATs). We show here that snf-11 encodes a functional GABA transporter; SNF-11–mediated GABA transport is Na+ and Cl? dependent, has an EC50 value of 168 ?M, and is blocked by the GAT1 inhibitor SKF89976A. The SNF-11 protein is expressed in seven GABAergic neurons, several additional neurons in the head and retrovesicular ganglion, and three groups of muscle cells. Therefore, all GABAergic synapses are associated with either presynaptic or postsynaptic (or both) expression of SNF-11. Although a snf-11 null mutation has no obvious effects on GABAergic behaviors, it leads to resistance to inhibitors of acetylcholinesterase. In vivo, a snf-11 null mutation blocks GABA uptake in at least a subset of GABAergic cells; in a cell culture system, all GABA uptake is abolished by the snf-11 mutation. We conclude that GABA transport activity is not essential for normal GABAergic function in C. elegans and that the localization of SNF-11 is consistent with a GABA clearance function rather than recycling. PMID:16641366

Mullen, Gregory P.; Mathews, Eleanor A.; Saxena, Paurush; Fields, Stephen D.; McManus, John R.; Moulder, Gary; Barstead, Robert J.; Quick, Michael W.

2006-01-01

250

Sequence relationships between integral inner membrane proteins of binding protein-dependent transport systems: evolution by recurrent gene duplications.  

PubMed Central

Periplasmic binding protein-dependent transport systems are composed of a periplasmic substrate-binding protein, a set of 2 (sometimes 1) very hydrophobic integral membrane proteins, and 1 (sometimes 2) hydrophilic peripheral membrane protein that binds and hydrolyzes ATP. These systems are members of the superfamily of ABC transporters. We performed a molecular phylogenetic analysis of the sequences of 70 hydrophobic membrane proteins of these transport systems in order to investigate their evolutionary history. Proteins were grouped into 8 clusters. Within each cluster, protein sequences displayed significant similarities, suggesting that they derive from a common ancestor. Most clusters contained proteins from systems transporting analogous substrates such as monosaccharides, oligopeptides, or hydrophobic amino acids, but this was not a general rule. Proteins from diverse bacteria are found within each cluster, suggesting that the ancestors of current clusters were present before the divergence of bacterial groups. The phylogenetic trees computed for hydrophobic membrane proteins of these permeases are similar to those described for the periplasmic substrate-binding proteins. This result suggests that the genetic regions encoding binding protein-dependent permeases evolved as whole units. Based on the results of the classification of the proteins and on the reconstructed phylogenetic trees, we propose an evolutionary scheme for periplasmic permeases. According to this model, it is probable that these transport systems derive from an ancestral system having only 1 hydrophobic membrane protein.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8003968

Saurin, W.; Dassa, E.

1994-01-01

251

Sequence relationships between integral inner membrane proteins of binding protein-dependent transport systems: evolution by recurrent gene duplications.  

PubMed

Periplasmic binding protein-dependent transport systems are composed of a periplasmic substrate-binding protein, a set of 2 (sometimes 1) very hydrophobic integral membrane proteins, and 1 (sometimes 2) hydrophilic peripheral membrane protein that binds and hydrolyzes ATP. These systems are members of the superfamily of ABC transporters. We performed a molecular phylogenetic analysis of the sequences of 70 hydrophobic membrane proteins of these transport systems in order to investigate their evolutionary history. Proteins were grouped into 8 clusters. Within each cluster, protein sequences displayed significant similarities, suggesting that they derive from a common ancestor. Most clusters contained proteins from systems transporting analogous substrates such as monosaccharides, oligopeptides, or hydrophobic amino acids, but this was not a general rule. Proteins from diverse bacteria are found within each cluster, suggesting that the ancestors of current clusters were present before the divergence of bacterial groups. The phylogenetic trees computed for hydrophobic membrane proteins of these permeases are similar to those described for the periplasmic substrate-binding proteins. This result suggests that the genetic regions encoding binding protein-dependent permeases evolved as whole units. Based on the results of the classification of the proteins and on the reconstructed phylogenetic trees, we propose an evolutionary scheme for periplasmic permeases. According to this model, it is probable that these transport systems derive from an ancestral system having only 1 hydrophobic membrane protein.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8003968

Saurin, W; Dassa, E

1994-02-01

252

Substrate Dependent Alterations of Organic Anion Transporting Polypeptide 1B3 (OATP1B3)  

E-print Network

Organic anion transporting polypeptides (OATPs) are multispecific transporters that mediate the uptake of numerous drugs and xenobiotics into cells. Alterations in the function of the liver–specific OATP1B1 and OATP1B3 have been shown to affect...

Roth, Megan Elizabeth

2011-12-31

253

Time dependent discrete ordinates neutron transport using distribution iteration in XYZ geometry  

Microsoft Academic Search

The distribution iteration (DI) algorithm, developed by Wager [32] and Prins [28], for solving the Boltzmann Transport Equation (BTE) has proven, with further development, to be a robust alternative to von Neumann iteration on the scattering source, aka source iteration (SI). Previous work with DI was based on the time-independent form of the transport equation. In this research, the DI

James R. Dishaw

2007-01-01

254

Parametric dependences of impurity transport in neoclassical, reactive drift wave and gyrokinetic descriptions  

Microsoft Academic Search

Impurity transport in tokamaks is studied using an electrostatic fluid model for main ion and impurity temperature gradient (ITG) mode and trapped electron (TE) mode driven turbulence and the results are compared with nonlinear gyrokinetic simulations using GYRO and neoclas- sical theory. Transport scalings with magnetic shear and impurity fraction are investigated, and the validity of the trace impurity approximation

H. Nordman; T. Fülöp; J Candy; P. Strand; J. Weiland

255

Effect of lipid acyl chain length on activity of sodium-dependent leucine transport system in Pseudomonas aeruginosa.  

PubMed

The sodium-dependent leucine transport system of Pseudomonas aeruginosa was reconstituted into liposomes of binary lipid mixtures of dilauroylphosphatidylethanolamine (di(12:0)PE)/phosphatidylcholine (PC) with cis-monounsaturated fatty acid chains (di(n:1)PC) (n = 14-22) or dioleoylphosphatidylethanolamine (di(18:1)PE)/di(n:1)PC (n = 14-22). Leucine carrier proteins can be activated with phosphatidylethanolamine, whereas activation does not occur in PC-reconstituted vesicles (Uratani, Y., and Aiyama, A. (1986) J. Biol. Chem. 261, 5450-5454). Na+-dependent counterflow was measured at 30 degrees C as reconstituted transport activity. Proteoliposomes containing di(12:0)PE exhibited high counterflow activity at the PC acyl carbon number (n) of 18 and 20 but no or low activity at n = 14, 16, and 22. On the other hand, proteoliposomes containing di(18:1)PE exhibited higher transport activity than those vesicles with di(12:0)PE and corresponding di(n:1)PC. A lipid mixture of di(18:1)PE and di(16:1)PC supported maximal activity. These results show that the leucine transport system of P. aeruginosa is dependent on the lipid acyl chain length and suggest that there exists optimal bilayer thickness for maximal carrier activity. PMID:3119594

Uratani, Y; Wakayama, N; Hoshino, T

1987-12-15

256

D6 PROTEIN KINASE activates auxin transport-dependent growth and PIN-FORMED phosphorylation at the plasma membrane.  

PubMed

The directed cell-to-cell transport of the phytohormone auxin by efflux and influx transporters is essential for proper plant growth and development. Like auxin efflux facilitators of the PIN-FORMED (PIN) family, D6 PROTEIN KINASE (D6PK) from Arabidopsis thaliana localizes to the basal plasma membrane of many cells, and evidence exists that D6PK may directly phosphorylate PINs. We find that D6PK is a membrane-bound protein that is associated with either the basal domain of the plasma membrane or endomembranes. Inhibition of the trafficking regulator GNOM leads to a rapid internalization of D6PK to endomembranes. Interestingly, the dissociation of D6PK from the plasma membrane is also promoted by auxin. Surprisingly, we find that auxin transport-dependent tropic responses are critically and reversibly controlled by D6PK and D6PK-dependent PIN phosphorylation at the plasma membrane. We conclude that D6PK abundance at the plasma membrane and likely D6PK-dependent PIN phosphorylation are prerequisites for PIN-mediated auxin transport. PMID:24930721

Barbosa, Inês C R; Zourelidou, Melina; Willige, Björn C; Weller, Benjamin; Schwechheimer, Claus

2014-06-23

257

Cloning and molecular characterization of the ontogeny of a rat ileal sodium-dependent bile acid transporter.  

PubMed Central

Sodium-dependent bile acid transport in the rat ileum is abruptly expressed at weaning. Degenerate oligonucleotides, based on amino acid sequence identities between the rat liver and hamster ileal transporters, were used to amplify a rat ileal probe. A 1.2-kb cDNA clone, which contains the full coding region (348 amino acids, 38 kD), was isolated by hybridization screening. In vitro translation yielded a 38-kD protein which glycosylated to 48 kD. Sodium-dependent uptake of taurocholate was observed in oocytes injected with cRNA. Northern blot analysis revealed a 5.0-kb mRNA in ileum, kidney, and cecum. A 48-kD protein was detected in ileal brush border membranes and localized to the apical border of villus ileal enterocytes. mRNA and protein expression, which were negligible before weaning, increased dramatically at weaning. Nuclear transcription rates for the transporter increased 15-fold between postnatal days 7 and 28. The apparent molecular weight of the transporter also increased between days 19 and 28. In summary, the developmental regulation of the rat ileal sodium-dependent bile acid cotransporter is characterized by transcriptionally regulated increases in mRNA and protein levels at the time of weaning with changes in apparent molecular weight of the protein after weaning. Images PMID:7860756

Shneider, B L; Dawson, P A; Christie, D M; Hardikar, W; Wong, M H; Suchy, F J

1995-01-01

258

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

USGS Publications Warehouse

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

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

2001-01-01

259

Grapevine MATE-Type Proteins Act as Vacuolar H+-Dependent Acylated Anthocyanin Transporters1[W][OA  

PubMed Central

In grapevine (Vitis vinifera), anthocyanins are responsible for most of the red, blue, and purple pigmentation found in the skin of berries. In cells, anthocyanins are synthesized in the cytoplasm and accumulated into the vacuole. However, little is known about the transport of these compounds through the tonoplast. Recently, the sequencing of the grapevine genome allowed us to identify genes encoding proteins with high sequence similarity to the Multidrug And Toxic Extrusion (MATE) family. Among them, we selected two genes as anthocyanin transporter candidates and named them anthoMATE1 (AM1) and AM3. The expression of both genes was mainly fruit specific and concomitant with the accumulation of anthocyanin pigment. Subcellular localization assays in grapevine hairy roots stably transformed with AM1? or AM3?green fluorescent protein fusion protein revealed that AM1 and AM3 are primarily localized to the tonoplast. Yeast vesicles expressing anthoMATEs transported acylated anthocyanins in the presence of MgATP. Inhibitor studies demonstrated that AM1 and AM3 proteins act in vitro as vacuolar H+-dependent acylated anthocyanin transporters. By contrast, under our experimental conditions, anthoMATEs could not transport malvidin 3-O-glucoside or cyanidin 3-O-glucoside, suggesting that the acyl conjugation was essential for the uptake. Taken together, these results provide evidence that in vitro the two grapevine AM1 and AM3 proteins mediate specifically acylated anthocyanin transport. PMID:19297587

Gomez, Camila; Terrier, Nancy; Torregrosa, Laurent; Vialet, Sandrine; Fournier-Level, Alexandre; Verries, Clotilde; Souquet, Jean-Marc; Mazauric, Jean-Paul; Klein, Markus; Cheynier, Veronique; Ageorges, Agnes

2009-01-01

260

Interactions of noncanonical motifs with hnRNP A2 promote activity-dependent RNA transport in neurons.  

PubMed

A key determinant of neuronal functionality and plasticity is the targeted delivery of select ribonucleic acids (RNAs) to synaptodendritic sites of protein synthesis. In this paper, we ask how dendritic RNA transport can be regulated in a manner that is informed by the cell's activity status. We describe a molecular mechanism in which inducible interactions of noncanonical RNA motif structures with targeting factor heterogeneous nuclear ribonucleoprotein (hnRNP) A2 form the basis for activity-dependent dendritic RNA targeting. High-affinity interactions between hnRNP A2 and conditional GA-type RNA targeting motifs are critically dependent on elevated Ca(2+) levels in a narrow concentration range. Dendritic transport of messenger RNAs that carry such GA motifs is inducible by influx of Ca(2+) through voltage-dependent calcium channels upon ?-adrenergic receptor activation. The combined data establish a functional correspondence between Ca(2+)-dependent RNA-protein interactions and activity-inducible RNA transport in dendrites. They also indicate a role of genomic retroposition in the phylogenetic development of RNA targeting competence. PMID:24841565

Muslimov, Ilham A; Tuzhilin, Aliya; Tang, Thean Hock; Wong, Robert K S; Bianchi, Riccardo; Tiedge, Henri

2014-05-26

261

Barriers to transport in aperiodically time-dependent two-dimensional velocity fields: Nekhoroshev's theorem and "Nearly Invariant" tori  

NASA Astrophysics Data System (ADS)

In this paper we consider fluid transport in two-dimensional flows from the dynamical systems point of view, with the focus on elliptic behaviour and aperiodic and finite time dependence. We give an overview of previous work on general nonautonomous and finite time vector fields with the purpose of bringing to the attention of those working on fluid transport from the dynamical systems point of view a body of work that is extremely relevant, but appears not to be so well known. We then focus on the Kolmogorov-Arnold-Moser (KAM) theorem and the Nekhoroshev theorem. While there is no finite time or aperiodically time-dependent version of the KAM theorem, the Nekhoroshev theorem, by its very nature, is a finite time result, but for a "very long" (i.e. exponentially long with respect to the size of the perturbation) time interval and provides a rigorous quantification of "nearly invariant tori" over this very long timescale. We discuss an aperiodically time-dependent version of the Nekhoroshev theorem due to Giorgilli and Zehnder (1992) (recently refined by Bounemoura, 2013 and Fortunati and Wiggins, 2013) which is directly relevant to fluid transport problems. We give a detailed discussion of issues associated with the applicability of the KAM and Nekhoroshev theorems in specific flows. Finally, we consider a specific example of an aperiodically time-dependent flow where we show that the results of the Nekhoroshev theorem hold.

Wiggins, S.; Mancho, A. M.

2014-02-01

262

Sodium-dependent net urea transport in rat initial inner medullary collecting ducts.  

PubMed Central

We reported that feeding rats 8% protein for 3 wk induces net urea transport and morphologic changes in initial inner medullary collecting ducts (IMCDs) which are not present in rats fed 18% protein. In this study, we measured net urea transport in microperfused initial IMCDs from rats fed 8% protein for > or = 3 wk and tested the effect of inhibiting Na+/K(+)-ATPase activity and found that adding 1 mM ouabain to the bath reversibly inhibited net urea transport from 14 +/- 3 to 6 +/- 2 pmol/mm per min (P < 0.01), and that replacing potassium (with sodium) in the bath reversibly inhibited net urea transport from 18 +/- 3 to 5 +/- 0 pmol/mm per min (P < 0.01). Replacing perfusate sodium with N-methyl-D-glucamine reversibly inhibited net urea transport from 12 +/- 2 to 0 +/- 1 pmol/mm per min (P < 0.01), whereas replacing bath sodium had no significant effect on net urea transport. Adding 10 nM vasopressin to the bath exerted no significant effect on net urea transport. Finally, we measured Na+/K(+)-ATPase activity in initial and terminal IMCDs from rats fed 18% or 8% protein and found no significant difference in either subsegment. Thus, net urea transport in initial IMCDs from rats fed 8% protein for > or = 3 wk requires sodium in the lumen, is reduced by inhibiting Na+/K(+)-ATPase, and is unchanged by vasopressin or phloretin. These results suggest that net urea transport may occur via a novel, secondary active, sodium-urea cotransporter. PMID:7929827

Isozaki, T; Lea, J P; Tumlin, J A; Sands, J M

1994-01-01

263

Kinetics of bidirectional H+ and substrate transport by the proton-dependent amino acid symporter PAT1  

PubMed Central

PAT1 is a recently identified member of the PAT family of proton/amino acid co-transporters with predominant expression in the plasma membrane of enterocytes and in lysosomal membranes of neurons. Previous studies in Xenopus oocytes expressing PAT1 established proton/substrate co-transport associated with positive inward currents for a variety of small neutral amino acids. Here we provide a detailed analysis of the transport mode of the murine PAT1 in oocytes using the two-electrode voltage-clamp technique to measure steady-state and pre-steady-state currents. The GPC (giant patch clamp) technique and efflux studies were employed to characterize the reversed transport mode. Kinetic parameters [Km (Michaelis constant) and Imax (maximum current)] for transport of various substrates revealed a dependence on membrane potential: hyperpolarization increases the substrate affinity and maximal transport velocity. Proton affinity for interaction with PAT1 is almost 100 nM, corresponding to a pH of 7.0 and is independent of substrate. Kinetic analysis revealed that binding of proton most likely occurs before substrate binding and that the proton and substrate are translocated in a simultaneous step. No evidence for a substrate-uncoupled proton shunt was observed. As shown by efflux studies and current measurements by the GPC technique, PAT1 allows bidirectional amino acid transport. Surprisingly, PAT1 exhibits no pre-steady-state currents in the absence of substrate, even at low temperatures, and therefore PAT1 takes an exceptional position among the ion-coupled co-transporters. PMID:15504109

2004-01-01

264

*Iron accumulation in bronchial epithelial cells is dependent on concurrent sodium transport  

EPA Science Inventory

Airway epithelial cells prevent damaging effects of extracellular iron by taking up the metal and sequestering it within intracellular ferritin. Epithelial iron transport is associated with transcellular movement of other cations including changes in the expression or activity of...

265

The products of YCF1 and YLL015w (BPT1) cooperate for the ATP-dependent vacuolar transport of unconjugated bilirubin in Saccharomyces cerevisiae.  

PubMed

Since bilirubin-like pigments are present in the environment as degradation products of heme-containing proteins, yeast could have developed a detoxifying system to transport these compounds into their vacuoles. Vacuoles from Saccharomyces cerevisiae showed an ATP-dependent, saturative transport of unconjugated bilirubin (UCB) that was reduced by 60% and 40% in YCF1 and YLL015w-deleted cells, respectively; the double deletant showed no UCB uptake. Conversely, the transport of bile acids (taurocholate) was comparable in wild and deleted stains. These data identify YCF1 and YLL015w, named BPT1 (Bile Pigment Transporter), as the genes responsible for ATP-dependent UCB transport in yeast. Since YCF1 and YLL015w are rather homologous with multidrug resistant proteins (MRPs), they also suggest the involvement of this class of transporters in the ATP-dependent transport of unconjugated bilirubin. PMID:10790694

Petrovic, S; Pascolo, L; Gallo, R; Cupelli, F; Ostrow, J D; Goffeau, A; Tiribelli, C; Bruschi, C V

2000-04-01

266

Azimuthal Jet Tomography at RHIC and LHC  

E-print Network

Results based on a generic jet-energy loss model that interpolates between running coupling pQCD-based and AdS/CFT-inspired holographic prescriptions are compared to recent data on the high-p_T pion nuclear modification factor and the high-p_T elliptic flow in nuclear collisions at RHIC and LHC. The jet-energy loss model is coupled to various (2+1)d (viscous hydrodynamic) fields. The impact of energy-loss fluctuations is discussed. While a previously proposed AdS/CFT jet-energy loss model with a temperature-independent jet-medium coupling is shown to be inconsistent with the LHC data, we find a rather broad class of jet-energy independent energy-loss models $dE/dx= \\kappa(T) x^z T^{2+z}$ that can account for the current data with different temperature-dependent jet-medium couplings $\\kappa(T)$ and path-length dependence exponents of $0\\le z \\le 2$.

Barbara Betz; Miklos Gyulassy

2014-07-28

267

Azimuthal Jet Tomography at RHIC and LHC  

E-print Network

Results based on a generic jet-energy loss model that interpolates between running coupling pQCD-based and AdS/CFT-inspired holographic prescriptions are compared to recent data on the high-p_T pion nuclear modification factor and the high-p_T elliptic flow in nuclear collisions at RHIC and LHC. The jet-energy loss model is coupled to various (2+1)d (viscous hydrodynamic) fields. The impact of energy-loss fluctuations is discussed. While a previously proposed AdS/CFT jet-energy loss model with a temperature-independent jet-medium coupling is shown to be inconsistent with the LHC data, we find a rather broad class of jet-energy independent energy-loss models $dE/dx= \\kappa(T) x^z T^{2+z}$ that can account for the current data with different temperature-dependent jet-medium couplings $\\kappa(T)$ and path-length dependence exponents of $0\\le z \\le 2$.

Betz, Barbara

2014-01-01

268

PINOID kinase regulates root gravitropism through modulation of PIN2-dependent basipetal auxin transport in Arabidopsis.  

PubMed

Reversible protein phosphorylation is a key regulatory mechanism governing polar auxin transport. We characterized the auxin transport and gravitropic phenotypes of the pinoid-9 (pid-9) mutant of Arabidopsis (Arabidopsis thaliana) and tested the hypothesis that phosphorylation mediated by PID kinase and dephosphorylation regulated by the ROOTS CURL IN NAPHTHYLPHTHALAMIC ACID1 (RCN1) protein might antagonistically regulate root auxin transport and gravity response. Basipetal indole-3-acetic acid transport and gravitropism are reduced in pid-9 seedlings, while acropetal transport and lateral root development are unchanged. Treatment of wild-type seedlings with the protein kinase inhibitor staurosporine phenocopies the reduced auxin transport and gravity response of pid-9, while pid-9 is resistant to inhibition by staurosporine. Staurosporine and the phosphatase inhibitor, cantharidin, delay the asymmetric expression of DR5revGFP (green fluorescent protein) at the root tip after gravistimulation. Gravity response defects of rcn1 and pid-9 are partially rescued by treatment with staurosporine and cantharidin, respectively. The pid-9 rcn1 double mutant has a more rapid gravitropic response than rcn1. These data are consistent with a reciprocal regulation of gravitropism by RCN1 and PID. Furthermore, the effect of staurosporine is lost in pinformed2 (pin2). Our data suggest that reduced PID kinase function inhibits gravitropism and basipetal indole-3-acetic acid transport. However, in contrast to PID overexpression studies, we observed wild-type asymmetric membrane distribution of the PIN2 protein in both pid-9 and wild-type root tips, although PIN2 accumulates in endomembrane structures in pid-9 roots. Similarly, staurosporine-treated plants expressing a PIN2GFP fusion exhibit endomembrane accumulation of PIN2GFP, but no changes in membrane asymmetries were detected. Our data suggest that PID plays a limited role in root development; loss of PID activity alters auxin transport and gravitropism without causing an obvious change in cellular polarity. PMID:19363095

Sukumar, Poornima; Edwards, Karin S; Rahman, Abidur; Delong, Alison; Muday, Gloria K

2009-06-01

269

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

PubMed

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

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

2010-09-01

270

Higher harmonics of azimuthal anisotropy in relativistic heavy ion collisions in HYDJET++ model  

E-print Network

The LHC data on azimuthal anisotropy harmonics from PbPb collisions at center-of-mass energy 2.76 TeV per nucleon pair are analyzed and interpreted in the framework of the HYDJET++ model. The cross-talk of elliptic $v_2$ and triangular $v_3$ flow in the model generates both even and odd harmonics of higher order. Comparison with the experimental data shows that this mechanism is able to reproduce the $p_{\\rm T}$ and centrality dependencies of quadrangular flow $v_4$, and also the basic trends for pentagonal $v_5$ and hexagonal $v_6$ flows.

L. V. Bravina; B. H. Brusheim Johansson; G. Kh. Eyyubova; V. L. Korotkikh; I. P. Lokhtin; L. V. Malinina; S. V. Petrushanko; A. M. Snigirev; E. E. Zabrodin

2013-11-27

271

The Azimuth Project: an open-access educational resource  

E-print Network

other things, the Azimuth Project includes: 1. A project to explain climate physics with the help physics with the help of software that runs on your browser. So far the focus is on energy balance models Project includes: 1. A project to explain climate physics with the help of software that runs on your

Baez, John

272

Tracking Source azimuth Using a Single Vector Sensor  

Microsoft Academic Search

This paper aims at estimating the azimuth of an underwater acoustic source with a single vector sensor. A vector sensor is a device that measures the scalar acoustic pressure field and the vectorial acoustic velocity field at a single location in space. The actual sensor technology allows to build compact vector sensors, with an operational frequency response ranging from a

Paulo Felisberto; Paulo Santos; S. M. Jesus

2010-01-01

273

Azimuthal Distribution of ULF Wave Power in the Magnetosphere  

NASA Astrophysics Data System (ADS)

The Van Allen radiation belts contain highly energetic particles which interact with a variety of plasma and MHD waves. ULF waves play an important role in loss and acceleration of energetic particles. There is still much to be understood about the interaction between charged particles and ULF waves and how these waves influence diffusion of charged particles. We will investigate how ULF wave power distribution in azimuth affects radial diffusion of charged particles. We will present results from CRRES (Combined Release and Radiation Effect Satellite) magnetometer data study regarding the azimuthal distribution of wave power in the geomagnetic field. Current theoretical treatments of radial diffusion assume a constant power distribution in azimuth while our results show that this is clearly not the case. Our ongoing investigation includes further study of azimuthal distribution of wave power as well as the distribution of wave power across different mode numbers. In order to use the in situ point measurements such as from a spacecraft, it is necessary to assume that all of the wave power exists in the first mode. But how valid is this assumption? How much power is contained in the higher modes? These are some of the questions we wish to investigate as a part of our ongoing study to better our understanding of particle dynamics in the magnetosphere.

Ali, A.; Elkington, S. R.

2013-12-01

274

Phenomenology of SIDIS unpolarized cross sections and azimuthal asymmetries  

E-print Network

I review the phenomenology of unpolarized cross sections and azimuthal asymmetries in semi-inclusive deeply inelastic scattering (SIDIS). The general theoretical framework is presented and the validity of the Gaussian model is discussed. A brief account of the existing analyses is provided.

Vincenzo Barone

2012-03-28

275

The Parker-shearing instability in azimuthally magnetized discs  

Microsoft Academic Search

We describe the effects of both magnetic buoyancy and differential rotation on a disc of isothermal gas embedded in a purely azimuthal magnetic field, in order to study the evolution and interplay of Parker and shearing instabilities. We perform a linear analysis of the evolution of perturbations in the shearing sheet model. Both instabilities occur on the slow MHD branch

Thierry Foglizzo; Michel Tagger

1995-01-01

276

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

277

Millennial Timescale Variations of Azimuthal Flows in the Earth's Core  

Microsoft Academic Search

Changes in the length of day at decade timescales and parts of the secular variation of the magnetic field can be both consistently explained by torsional oscillations in the Earth's fluid core. This type of flow is predicted by theory and consists of azimuthal oscillations of rigid cylindrical surfaces aligned with the rotation axis. In this work, we apply the

M. Dumberry; J. Bloxham

2004-01-01

278

Azimuthal asymmetries and vibrational modes in bubble pinch-off  

Microsoft Academic Search

The pressure-driven inertial collapse of a cylindrical void in an inviscid liquid is an integrable, Hamiltonian system that forms a finite-time singularity as the radius of the void collapses to zero. Here it is shown that when the natural cylindrical symmetry of the void is perturbed azimuthally, the perturbation modes neither grow nor decay, but instead cause constant amplitude vibrations

Laura E. Schmidt

2008-01-01

279

Azimuthal Asymmetries and Vibrational Modes in Bubble Pinch-off  

Microsoft Academic Search

The pressure-driven inertial collapse of a cylindrical void in an inviscid liquid is an integrable, Hamiltonian system that forms a finite-time singularity as the radius of the void collapses to zero. Here it is shown that when the natural cylindrical symmetry of the void is perturbed azimuthally, the perturbation modes neither grow nor decay, but instead cause constant amplitude vibrations

Laura E Schmidt

2011-01-01

280

AZIMUTHAL VARIATION OF RADIATION OF SEISMIC ENERGY FROM CAST BLASTS  

E-print Network

AZIMUTHAL VARIATION OF RADIATION OF SEISMIC ENERGY FROM CAST BLASTS D. Craig Pearson Brian W. Stump VARIATION OF RADIATION OF SEISMIC ENERGY FROM CAST BLASTS D. Craig Pearson and Brian W. Stump Los Alamos network of three-component seismic sensors were deployed around a large cast shot in the Black Thunder

281

Kinetics and Energetics of Mg 2+ ,ATP-Dependent Ca 2+ Transport in the Plasma Membrane of Smooth Muscle Cells  

Microsoft Academic Search

Calcium ions play a crucial role in the excitation\\/contraction coupling in smooth muscles. I would like to interpret the biochemical mechanisms underlying Ca2+ exchange and dynamics of such an exchange in the smooth muscles. Particular emphasis is laid on the examination of kinetic, energetic, and catalytic properties of the membrane-linked energy-dependent Ca2+-transporting systems involved in regulation of the intracellular Ca2+

S. O. Kosterin

2003-01-01

282

The Nramp orthologue of Cryptococcus neoformans is a pH-dependent transporter of manganese, iron, cobalt and nickel  

PubMed Central

Cryptococcus neoformans is an important human opportunistic pathogen and a facultative intracellular parasite, particularly in HIV-infected individuals. Little is known about metal ion transport in this organism. C. neoformans encodes a single member of the Nramp (natural resistance-associated macrophage protein) family of bivalent cation transporters, known as Cramp, which we have cloned and expressed in Xenopus laevis oocytes and Spodoptera frugiperda Sf 21 insect cells. Cramp induces saturable transport of a broad range of bivalent transition series cations, including Mn2+, Fe2+, Co2+ and Ni2+. Maximal cation transport occurs at pH 5.5–6.0, consistent with the proton gradient-based energetics of other Nramp orthologues. Mn2+ transport is diminished in the presence of 140 mM Na+, compatible with a Na+ slippage mechanism proposed for the Saccharomyces cerevisiae Nramp orthologue Smf1p. Cramp resembles Smf1p with respect to predicted membrane topology, substrate specificity and pH dependence, but differs in terms of its apparent affinity for Mn2+ and negligible inhibition by Zn2+. Cramp is the first Nramp orthologue from a fungal pathogen to be functionally characterized. Insights afforded by these findings will allow the formulation of new hypotheses regarding the role of metal ions in the pathophysiology of cryptococcosis. PMID:15350193

2004-01-01

283

The N-terminal Domain of a TonB-dependent Transporter Undergoes a Reversible Stepwise Denaturation†  

PubMed Central

Gram-negative bacteria contain a family of outer membrane transport proteins that function in the uptake of rare nutrients, such as iron and vitamin B12. These proteins are termed TonB-dependent because transport requires an interaction with the inner membrane protein TonB. Using a combination of site-directed spin labeling and chemical denaturation, we examined the site-specific unfolding of regions of the Escherichia coli vitamin B12 transporter, BtuB. The data indicate that a portion of the N-terminal region of the protein, which occupies the lumen of the BtuB barrel, denatures prior to the unfolding of the barrel and that the free energy of folding for the N-terminus is less than that typically seen for globular proteins. Moreover, the data indicate that the N-terminal domain does not unfold in a single event, but unfolds in a series of independent steps. The unfolding of the N-terminus is reversible and removal of denaturant restores the native fold of the protein. These data are consistent with proposed transport mechanisms that involve a transient rearrangement or unfolding of the protein N-terminus, and they provide evidence for a specific protein conformation that might be an intermediate accessed during transport. PMID:22497281

Flores Jiménez, Ricardo H.; Cafiso, David S.

2012-01-01

284

Identification of an ATP-dependent copper transport system in endoplasmic reticulum vesicles isolated from rat liver.  

PubMed Central

1. This paper identifies and characterizes an ATP-dependent copper transport system in endoplasmic reticulum vesicles isolated from male rat liver. 2. The transporter has a Km of 2.5 +/- 1.2 mumol 1(-1) copper glutathione (CuGSH) and a Vmax of 4.5 +/- 1.3 nmol (mg protein)-1 (5 min)-1 for copper. 3. At a copper concentration of 2 mumol l-1, ATP dependence reaches saturation, with a Km for ATP of 4.7 +/- 2.4 mmol l-1 and a Vmax of 2.8 +/- 0.6 nmol (mg protein)-1 (5 min)-1. 4. The uptake is dependent on ATP hydrolysis, since a low energy analogue of ATP, adenosine 5'-[beta-gamma-methylene] triphosphate tetralithium (AMP.PCP), has no effect on copper uptake. 5. The transporter is a P-type ATPase, since vanadate inhibits uptake with a high degree of specificity (100 mumol l-1 inhibits uptake by 50% at a copper concentration of 2 mumol l-1). PMID:7738849

Bingham, M J; Burchell, A; McArdle, H J

1995-01-01

285

[Nitric oxide as a possible regulator of energy-dependent Ca2+ transport in mitochondria of uterine smooth muscle].  

PubMed

The influence of the donor and the precursor of NO, namely 100 mM sodium nitroprusside and sodium nitrite on the energo-dependent Ca(2+)-transport in isolated mitochondria from rat myometrium was investigated. Changes in the mitochondrial matrix Ca(2+)-concentration was evaluated by spectrofluorimetry using Ca2+ sensitive probe Fluo-4 AM. Mg(2+)-ATP-dependent Ca(2+)-accumulation on mitochondria in the presence of succinate significantly stimulated by nitric oxide, in particular, 100 microM sodium nitroprusside amplified the transport by 1.6 times relative to its control values. NO effect becomes significant only when the incubation of mitochondria with the compounds was performed. Ca(2+)-accumulation in the presence of sodium nitroprusside effectively suppressed by protonophore (CCCP) and ruthenium red (10 microM). It was concluded that inner mitochondrial membrane Ca(2+)-uniporter stimulated by nitrogen oxide. Ca(2+)-accumulation in mitochondria in the presence of sodium nitroprusside was not sensitive to the action of a specific permeability transition pore inhibitor cyclosporine (5 microM). This data indicates that the role of permeability transition pore is less significant than Ca(2+)-uniporter in the processes of Ca(2+)-transport in mitochondria under the nitric oxide action. Thus, nitric oxide stimulates the energo-dependent Ca(2+)-accumulation by myometrium mitochondria mediated their inner membrane Ca(2+)-uniporter functioning. PMID:25007515

Danylovych, Iu V; Kolomiiets', O V; Danylovych, H V; Kosterin, S O

2014-01-01

286

Crocidolite asbestos fibers undergo size-dependent microtubule-mediated transport after endocytosis in vertebrate lung epithelial cells.  

PubMed

The large respiratory epithelial cells within primary cultures of newt (Taricha granulosa) lung are uniquely suited for high resolution video-enhanced light-microscopic studies. We show here that these cells incorporate crocidolite asbestos fibers within 18 h by endocytosis. Once inside the cell, fibers less than 5 microns in length are seen by video light microscopy to undergo saltatory transport at a maximum velocity of 1.18 microns/s. By contrast, fibers over 5 microns long rarely exhibit saltatory motion. Over time, all of the fibers become preferentially located near the nucleus. This perinuclear accumulation is largely inhibited by disassembling the cytoplasmic microtubules with nocodazole. Same cell correlative light and electron microscopy reveal that fibers exhibiting saltatory behavior are enclosed within a membrane. From these observations we conclude that, upon incorporation into epithelial cells, asbestos fibers undergo size-dependent active transport along cytoplasmic microtubules. Our data are the first to link the dimension-dependent transforming ability of asbestos fibers to a basic cellular function, i.e., the microtubule-dependent transport of cellular components. PMID:1893384

Cole, R W; Ault, J G; Hayden, J H; Rieder, C L

1991-09-15

287

P2Y1 receptor inhibits GABA transport through a calcium signalling-dependent mechanism in rat cortical astrocytes.  

PubMed

Astrocytes express a variety of purinergic (P2) receptors, involved in astrocytic communication through fast increases in [Ca(2+) ]i . Of these, the metabotropic ATP receptors (P2Y) regulate cytoplasmic Ca(2+) levels through the PLC-PKC pathway. GABA transporters are a substrate for a number of Ca(2+) -related kinases, raising the possibility that calcium signalling in astrocytes impact the control of extracellular levels of the major inhibitory transmitter in the brain. To access this possibility we tested the influence of P2Y receptors upon GABA transport into astrocytes. Mature primary cortical astroglial-enriched cultures expressed functional P2Y receptors, as evaluated through Ca(2+) imaging, being P2Y1 the predominant P2Y receptor subtype. ATP (100 ?M, for 1 min) caused an inhibition of GABA transport through either GAT-1 or GAT-3 transporters, decreasing the Vmax kinetic constant. ATP-induced inhibition of GATs activity was still evident in the presence of adenosine deaminase, precluding an adenosine-mediated effect. This, was mimicked by a specific agonist for the P2Y1,12,13 receptor (2-MeSADP). The effect of 2-MeSADP on GABA transport was blocked by the P2 (PPADS) and P2Y1 selective (MRS2179) receptor antagonists, as well as by the PLC inhibitor (U73122). 2-MeSADP failed to inhibit GABA transport in astrocytes where intracellular calcium had been chelated (BAPTA-AM) or where calcium stores were depleted (?-cyclopiazonic acid, CPA). In conclusion, P2Y1 receptors in astrocytes inhibit GABA transport through a mechanism dependent of P2Y1 -mediated calcium signalling, suggesting that astrocytic calcium signalling, which occurs as a consequence of neuronal firing, may operate a negative feedback loop to enhance extracellular levels of GABA. PMID:24733747

Jacob, Pedro F; Vaz, Sandra H; Ribeiro, Joaquim A; Sebastião, Ana M

2014-08-01

288

Zeaxanthin Formation and Energy-Dependent Fluorescence Quenching in Pea Chloroplasts under Artificially Mediated Linear and Cyclic Electron Transport 1  

PubMed Central

Artificially mediated linear (methylviologen) and cyclic (phenazine methosulfate) electron transport induced zeaxanthin-dependent and independent (constitutive) nonphotochemical quenching in osmotically shocked chloroplasts of pea (Pisum sativum L. cv Oregon). Nonphotochemical quenching was quantitated as Stern-Volmer quenching (SVN) calculated as (Fm/F?m)-1 where Fm is the fluorescence intensity with all PSII reaction centers closed in a nonenergized, dark-adapted state and F?m is the fluorescence intensity with all PSII reaction centers closed in an energized state. Reversal of quenching by nigericin and electron-transport inhibitors showed that both quenching types were energy-dependent SVN. Under light-induced saturating ?pH, constitutive-SVN reached steady-state in about 1 minute whereas zeaxanthin-SVN continued to develop for several minutes in parallel with the slow kinetics of violaxanthin deepoxidation. SVN above the constitutive level and relative zeaxanthin concentration showed high linear correlations at steady-state and during induction. Furthermore, Fo quenching, also treated as Stern-Volmer quenching (SVO) and calculated as (Fo/F?o)-1, showed high correlation with zeaxanthin and consequently with SVN (Fo and F?o are fluorescence intensities with all PSII reaction centers in nonenergized and energized states, respectively). These results support the view that zeaxanthin increases SVN above the constitutive level in a concentration-dependent manner and that zeaxanthin-dependent SVN occurs in the pigment bed. Preforming zeaxanthin increased the rate and extent of SVN, indicating that slow events other than the amount of zeaxanthin also affect final zeaxanthin-SVN expression. The redox state of the primary electron acceptor of photosystem II did not appear to determine SVN. Antimycin, when added while chloroplasts were in a dark-adapted or nonenergized state, inhibited both zeaxanthin-SVN and constitutive-SVN induced by linear and cyclic electron transport. These similarities, including possible constitutive Fo quenching, suggest that zeaxanthin-dependent and constitutive SVN are mechanistically related. PMID:16668233

Gilmore, Adam M.; Yamamoto, Harry Y.

1991-01-01

289

Experimental and theoretical study of nickel transport dependence on gradients in Tore Supra  

NASA Astrophysics Data System (ADS)

This paper reports on a Tore Supra experiment consisting in modifying locally the normalized electron temperature gradient R?Te/Te by playing with the electron cyclotron heating wave power deposition radius. Trace nickel was injected by the laser blow-off technique and its behaviour in the plasma has been analysed using a radial impurity transport code. The diffusion coefficient has been found to decrease steeply when |R?Te/Te| is decreased in conditions where linear gyrokinetic calculations find that turbulence is dominated by modes propagating in the electron drift direction. An experimental turbulence threshold for nickel transport has been deduced.

Villegas, D.; Guirlet, R.; Bourdelle, C.; Garbet, X.; Hoang, G. T.; Sabot, R.; Imbeaux, F.; Ségui, J. L.

2014-07-01

290

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

PubMed

Anion and fluid secretion are both defective in cystic fibrosis (CF); however, the transport mechanisms are not well understood. In this study, Cl(-) and HCO(3)(-) secretion was measured using genetically matched CF transmembrane conductance regulator (CFTR)-deficient and CFTR-expressing cell lines derived from the human airway epithelial cell line Calu-3. Forskolin stimulated the short-circuit current (I(sc)) across voltage-clamped monolayers, and also increased the equivalent short-circuit current (I(eq)) calculated under open-circuit conditions. I(sc) was equivalent to the HCO(3)(-) net flux measured using the pH-stat technique, whereas I(eq) was the sum of the Cl(-) and HCO(3)(-) net fluxes. I(eq) and HCO(3)(-) fluxes were increased by bafilomycin and ZnCl(2), suggesting that some secreted HCO(3)(-) is neutralized by parallel electrogenic H(+) secretion. I(eq) and fluid secretion were dependent on the presence of both Na(+) and HCO(3)(-). The carbonic anhydrase inhibitor acetazolamide abolished forskolin stimulation of I(eq) and HCO(3)(-) secretion, suggesting that HCO(3)(-) transport under these conditions requires catalysed synthesis of carbonic acid. Cl(-) was the predominant anion in secretions under all conditions studied and thus drives most of the fluid transport. Nevertheless, 50-70% of Cl(-) and fluid transport was bumetanide-insensitive, suggesting basolateral Cl(-) loading by a sodium-potassium-chloride cotransporter 1 (NKCC1)-independent mechanism. Imposing a transepithelial HCO(3)(-) gradient across basolaterally permeabilized Calu-3 cells sustained a forskolin-stimulated current, which was sensitive to CFTR inhibitors and drastically reduced in CFTR-deficient cells. Net HCO(3)(-) secretion was increased by bilateral Cl(-) removal and therefore did not require apical Cl(-)/HCO(3)(-) exchange. The results suggest a model in which most HCO(3)(-) is recycled basolaterally by exchange with Cl(-), and the resulting HCO(3)(-)-dependent Cl(-) transport provides an osmotic driving force for fluid secretion. PMID:22777674

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

2012-11-01

291

Transportation  

Microsoft Academic Search

India, a country over one billion population has been facing serious difficulty of urban congestion and traffic jams since 1970's in her major cities. Public transport system in Mumbai has been overworking three times its capacity. Public transport system in Delhi, Colcutta and Chennai is also under strain. Elevated railway and underground railway could be options to support overworked surface

Makarand Gulawani

292

Numerical modeling of tidal influence on density-dependent contaminant transport  

Microsoft Academic Search

Transport of contaminants in coastal aquifers subject to tidal fluctuation is an important topic in hydrogeology as a consequence of the significant development of human activities near the shoreline. Despite this, relatively little work has been done to investigate the joint effect of variable water density flow and tidal saltwater head fluctuation. In particular, numerical modeling results have rarely been

A. Brovelli; X. Mao; D. A. Barry

2007-01-01

293

Phospholipid-dependent regulation of cytochrome c3-mediated electron transport across membranes.  

PubMed

Cytochrome c3 (cyt c3) can mediate electron transport across phosphatidylcholine (PC)/cardiolipin (CL) and PC/phosphatidylglycerol (PG) membranes. A two-molecule process is involved in the electron transport across PC/CL membranes in the liquid-crystalline state. In contrast, a single-molecule process dominates the electron transport across PC/CL membranes in the gel state and PC/PG membranes in the liquid-crystalline and gel states. Namely, the electron transport mechanism differs with the phospholipid composition and membrane fluidity. The rate-limiting step of the two-molecule process was lateral diffusion of cyt c3 in membranes. The rate constants for the three single-molecule process cases were similar to each other. To elucidate these reaction processes, interactions between cyt c3 and phosphate groups and between cyt c3 and the glycerol backbones of phospholipid bilayers were investigated by means of 31P and 2H solid-state NMR, respectively, for CL and PC/CL membranes. The results showed that the polar headgroups of both phosphatidylcholine and CL are involved in the binding of cyt c3. Also, cyt c3 penetrates into membranes, which would induce distortion of the lipid bilayer. The molecular mechanisms underlying the single- and two-molecule processes are discussed in terms of membrane structure. PMID:16258050

Kim, Suhk-mann; Yamamoto, Toshinori; Todokoro, Yasuto; Takayama, Yuki; Fujiwara, Toshimichi; Park, Jang-Su; Akutsu, Hideo

2006-01-15

294

A KINETIC MODEL FOR CELL DENSITY DEPENDENT BACTERIAL TRANSPORT IN POROUS MEDIA  

EPA Science Inventory

A kinetic transport model with the ability to account for variations in cell density of the aqueous and solid phases was developed for bacteria in porous media. Sorption kinetics in the advective-dispersive-sorptive equation was described by assuming that adsorption was proportio...

295

Cloning and functional characterization of the human sodium-dependent vitamin C transporters hSVCT1 and hSVCT2.  

PubMed

Two sodium-dependent vitamin C transporters, hSVCT1 and hSVCT2, were cloned from a human kidney cDNA library. hSVCT1 had a 1797 bp open reading frame encoding a 598 amino acid polypeptide. The 1953 bp open reading frame of hSVCT2 encoded a 650 amino acid polypeptide. Using a Xenopus laevis oocyte expression system, both transporters were functionally expressed. By Eadie-Hofstee transformation the apparent K(m) of hSVCT1 for ascorbate was 252.0 microM and of hSVCT2 for ascorbate was 21.3 microM. Both transporters were sodium-dependent and did not transport dehydroascorbic acid. Incubation of oocytes expressing either transporter with phorbol 12-myristate 13-acetate (PMA) inhibited ascorbate transport activity. Availability of the human transporter clones may facilitate new strategies for determining vitamin C intake. PMID:10556521

Daruwala, R; Song, J; Koh, W S; Rumsey, S C; Levine, M

1999-11-01

296

Salvinorin A regulates dopamine transporter function via a kappa opioid receptor and ERK1/2-dependent mechanism.  

PubMed

Salvinorin A (SalA), a selective ?-opioid receptor (KOR) agonist, produces dysphoria and pro-depressant like effects. These actions have been attributed to inhibition of striatal dopamine release. The dopamine transporter (DAT) regulates dopamine transmission via uptake of released neurotransmitter. KORs are apposed to DAT in dopamine nerve terminals suggesting an additional target by which SalA modulates dopamine transmission. SalA produced a concentration-dependent, nor-binaltorphimine (BNI)- and pertussis toxin-sensitive increase of ASP(+) accumulation in EM4 cells coexpressing myc-KOR and YFP-DAT, using live cell imaging and the fluorescent monoamine transporter substrate, trans 4-(4-(dimethylamino)-styryl)-N-methylpyridinium) (ASP(+)). Other KOR agonists also increased DAT activity that was abolished by BNI pretreatment. While SalA increased DAT activity, SalA treatment decreased serotonin transporter (SERT) activity and had no effect on norepinephrine transporter (NET) activity. In striatum, SalA increased the Vmax for DAT mediated DA transport and DAT surface expression. SalA up-regulation of DAT function is mediated by KOR activation and the KOR-linked extracellular signal regulated kinase-½ (ERK1/2) pathway. Co-immunoprecipitation and BRET studies revealed that DAT and KOR exist in a complex. In live cells, DAT and KOR exhibited robust FRET signals under basal conditions. SalA exposure caused a rapid and significant increase of the FRET signal. This suggests that the formation of KOR and DAT complexes is promoted in response to KOR activation. Together, these data suggest that enhanced DA transport and decreased DA release resulting in decreased dopamine signalling may contribute to the dysphoric and pro-depressant like effects of SalA and other KOR agonists. PMID:25107591

Kivell, Bronwyn; Uzelac, Zeljko; Sundaramurthy, Santhanalakshmi; Rajamanickam, Jeyaganesh; Ewald, Amy; Chefer, Vladimir; Jaligam, Vanaja; Bolan, Elizabeth; Simonson, Bridget; Annamalai, Balasubramaniam; Mannangatti, Padmanabhan; Prisinzano, Thomas E; Gomes, Ivone; Devi, Lakshmi A; Jayanthi, Lankupalle D; Sitte, Harald H; Ramamoorthy, Sammanda; Shippenberg, Toni S

2014-11-01

297

Reconstitution of ATP-dependent cGMP transport into proteoliposomes by membrane proteins from human erythrocytes.  

PubMed

The cellular efflux of cGMP from human erythrocytes has previously been characterized in functional studies. The purpose of the present study was to find membrane proteins with the ability to restore ATP-dependent uptake of cGMP into proteoliposomes. Human erythrocyte membranes were solubilized with CHAPS (3-([3-cholamidopropyl]dimethylammonio)-1-propanesulfonate) and gel filtration gave three protein fractions with the ability to restore active transport. Only two of these fractions were retained on a lentil lectin column. By using these two purification steps, active transport was 11 times higher in the first fraction compared to the original material and SDS-PAGE showed the presence of proteins with sizes of 145 kDa and 165 kDa. The second fraction gave 20 times higher active transport after purification and comprised proteins with sizes of 145 kDa and 180 kDa. At present three members of the MRP (multi-resistance associated protein) family have been detected in human erythrocytes: MRPI, MRP4 and MRP5. The last two proteins have been shown to transport cyclic nucleotides. The present findings are compatible with MRP4 as the 145 kDa protein, MRP5 as the 165 kDa protein and MRP1 as the 180 kDa protein. However, the 145 kDa protein could also be SMRP (short multi-resistance protein), the gene splice variant of MRP5. Immunoprecipitation of MRP5 from CHAPS-solubilized extract reduced active transport and specific binding by about 45% and 40%, respectively. This shows that MRP5 is an important cGMP-transporting protein in human erythrocytes. PMID:15025427

Boadu, E; Sager, G

2004-01-01

298

The human multidrug-resistance-associated protein MRP1 mediates ATP-dependent transport of unconjugated bilirubin  

PubMed Central

Results of previous studies have suggested that UCB (unconjugated bilirubin) may be transported by MRP1/Mrp1 (multidrug-resistance-associated protein 1). To test this hypothesis directly, [3H]UCB transport was assessed in plasma-membrane vesicles from MDCKII cells (Madin–Darby canine kidney II cells) stably transfected with human MRP1 or MRP2; wild-type MDCKII cells served as controls. As revealed by Western blotting, transfection achieved abundant expression of MRP1 and MRP2. [3H]UCB uptake was measured in the presence of 60 ?M human serum albumin at a free (unbound) concentration of UCB (BF) ranging from 5 to 72 nM and in the presence of 3 mM ATP or 3 mM AMP-PCP (adenosine 5?-[?,?-methylene]triphosphate). MRP1-transfected vesicles showed transport activity three and five times higher respectively compared with MRP2 or wild-type vesicles, whose transport did not differ significantly. [3H]UCB transport was stimulated 4-fold by 1.5 mM GSH, occurred into an osmotically sensitive space, was inhibited by 3 ?M MK571 and followed saturative kinetics with Km=10±3 nM (BF) and Vmax=100±13 pmol·min?1·(mg of protein)?1. UCB significantly inhibited the transport of LTC4 (leukotriene C4), a leukotriene substrate known to have high affinity for MRP1. Collectively, these results prove directly that MRP1 mediates ATP-dependent cellular export of UCB and supports its role in protecting cells from bilirubin toxicity. PMID:15245331

2004-01-01

299

The human multidrug-resistance-associated protein MRP1 mediates ATP-dependent transport of unconjugated bilirubin.  

PubMed

Results of previous studies have suggested that UCB (unconjugated bilirubin) may be transported by MRP1/Mrp1 (multidrug-resistance-associated protein 1). To test this hypothesis directly, [3H]UCB transport was assessed in plasma-membrane vesicles from MDCKII cells (Madin-Darby canine kidney II cells) stably transfected with human MRP1 or MRP2; wild-type MDCKII cells served as controls. As revealed by Western blotting, transfection achieved abundant expression of MRP1 and MRP2. [3H]UCB uptake was measured in the presence of 60 microM human serum albumin at a free (unbound) concentration of UCB (B(F)) ranging from 5 to 72 nM and in the presence of 3 mM ATP or 3 mM AMP-PCP (adenosine 5'-[beta,gamma-methylene]triphosphate). MRP1-transfected vesicles showed transport activity three and five times higher respectively compared with MRP2 or wild-type vesicles, whose transport did not differ significantly. [3H]UCB transport was stimulated 4-fold by 1.5 mM GSH, occurred into an osmotically sensitive space, was inhibited by 3 microM MK571 and followed saturative kinetics with K(m)=10+/-3 nM (B(F)) and V(max)=100+/-13 pmol x min(-1) x (mg of protein)(-1). UCB significantly inhibited the transport of LTC4 (leukotriene C4), a leukotriene substrate known to have high affinity for MRP1. Collectively, these results prove directly that MRP1 mediates ATP-dependent cellular export of UCB and supports its role in protecting cells from bilirubin toxicity. PMID:15245331

Rigato, Igino; Pascolo, Lorella; Fernetti, Cristina; Ostrow, J Donald; Tiribelli, Claudio

2004-10-15

300

Activity-dependent transport of GABA analogues into specific cell types demonstrated at high resolution using a novel immunocytochemical strategy.  

PubMed

We have raised antisera against the GABA analogues gamma-vinyl GABA, diaminobutyric acid and gabaculine. These analogues are thought to be substrates for high-affinity GABA transporters. Retinae were exposed to micromolar concentrations of these analogues in the presence or absence of uptake inhibitors and then fixed and processed for immunocytochemistry at the light and electron microscopic levels. Immunolabelling for gamma-vinyl GABA revealed specific labelling of GABAergic amacrine cells and displaced amacrine cells in retinae of rabbits, cats, chickens, fish and a monkey. GABA-containing horizontal cells of cat and monkey retinae failed to exhibit labelling for gamma-vinyl GABA, suggesting that they lacked an uptake system for this molecule. In light-adapted fish, gamma-vinyl GABA was readily detected in H1 horizontal cells; similar labelling was also observed in light-adapted chicken retinae. The pattern of labelling in the fish and chicken retinae was modified by dark adaptation, when labelling was greatly reduced in the horizontal cells, indicating the activity dependence of GABA (analogue) transport. Intraperitoneal injection of gamma-vinyl GABA into rats resulted in its transport across the blood-brain barrier and subsequent uptake into populations of GABAergic neurons. The other analogues investigated in this study exhibited different patterns of transport; gabaculine was taken up into glial cells, whilst diaminobutyric acid was taken up into neurons, glial cells and retinal pigment epithelia. Thus, these analogues are probably substrates for different GABA transporters. We conclude that immunocytochemical detection of the high-affinity uptake of gamma-vinyl GABA permits the identification of GABAergic neurons which are actively transporting GABA, and suggest that this novel methodology will be a useful tool in rapidly assessing the recent activity of GABAergic neurons at the cellular level. PMID:8809830

Pow, D V; Baldridge, W; Crook, D K

1996-08-01

301

Zinc transporter ZnT-3 regulates presynaptic Erk1/2 signaling and hippocampus-dependent memory.  

PubMed

The physiological role of vesicular zinc at central glutamatergic synapses remains poorly understood. Here we show that mice lacking the synapse-specific vesicular zinc transporter ZnT3 (ZnT3KO mice) have reduced activation of the Erk1/2 MAPK in hippocampal mossy fiber terminals, disinhibition of zinc-sensitive MAPK tyrosine phosphatase activity, and impaired MAPK signaling during hippocampus-dependent learning. Activity-dependent exocytosis is required for the effect of zinc on presynaptic MAPK and phosphatase activity. ZnT3KO mice have complete deficits in contextual discrimination and spatial working memory. Local blockade of zinc or MAPK in the mossy fiber pathway of wild-type mice impairs contextual discrimination. We conclude that ZnT3 is important for zinc homeostasis modulating presynaptic MAPK signaling and is required for hippocampus-dependent memory. PMID:21245308

Sindreu, Carlos; Palmiter, Richard D; Storm, Daniel R

2011-02-22

302

Temperature- and density-dependent transport regimes in a h-BN/bilayer graphene/h-BN heterostructure  

NASA Astrophysics Data System (ADS)

We report on multiterminal electrical transport measurements performed on a bilayer graphene sheet enclosed by two hexagonal boron nitride flakes. We characterize the temperature dependence of electrical resistivity from 300 mK to 50 K, varying the carrier densities with a back gate. The resistivity curves clearly show a temperature-independent crossing point at density n =nc?2.5×1011 cm-2 for both positive and negative carriers, separating two distinct regions with d? /dT<0 and d? /dT>0, respectively. Our analysis rules out the possibility of a zero-T quantum phase transition, revealing instead the onset of robust ballistic transport for n >nc, while the T dependence close to the neutrality point is the one expected from the parabolic energy-momentum relation. At low temperature (T ?10 K), the data are compatible with transport via variable range hopping mediated by localized impurity sites, with a characteristic exponent 1/3 that is renormalized to 1/2 by Coulomb interaction in the high-density regime.

Cobaleda, C.; Pezzini, S.; Diez, E.; Bellani, V.

2014-03-01

303

Multiterminal multimode spin-dependent scattering matrix formalism: Electron and hole quantum spin transport in multiterminal junctions  

NASA Astrophysics Data System (ADS)

We present a derivation of a scattering matrix method providing an exact multimode solution to spin-dependent quantum transport in multiterminal structures. The method is formulated in a general language such that it can readily be applied to any spin- S system with spin interactions. We apply the formalism to spin-1/2 electron and spin-3/2 hole transport in three- and four-terminal structures. It is shown that the existence of a third lead lifts constraints on the flux polarization of two-terminal electron transport. A spin-rectification property in a three-terminal system with Rashba spin-orbit interaction is demonstrated. We furthermore find that a four-terminal structure can partition a fully spin-polarized electron flux into two oppositely polarized fluxes. For holes, we calculate the polarization vector of both the injected states as well as the outgoing states in a three-terminal structure. Close to the onset of propagating channels, the hole polarization exhibits peak-dip structures attributed to the angular-momentum dependent Fano resonances in the three-terminal junction. We rigorously show that when the outgoing state is restricted to a single channel, the polarization is uniquely determined by the outgoing lead state, independent of the scattering details of the structure.

Brusheim, P.; Csontos, D.; Zülicke, U.; Xu, H. Q.

2008-08-01

304

Effects of Polarization Azimuth of Writing Beams on Diffraction Properties in Vector Holograms Using Radially Polarized Light  

NASA Astrophysics Data System (ADS)

It is very important for realizing the polarization-multiplex holographic memory to clarify the optical properties of vector holograms recorded using the inhomogeneous polarized beams. In the present paper we present a simple yet useful method using the radially polarized writing beams to systematically investigate the optical properties of complicated vector holograms and preliminary data about effects of polarization azimuth of writing beams on diffraction properties. The diffraction properties of the vector holograms written in the azobenzene-containing polymers were strongly dependent on the angle between the grating vector and polarization azimuth of the writing beam. Considering the above-mentioned dependence, the theoretical calculation on the basis of Jones calculus revealed optical properties of the vector holograms written by various types of radially polarized beams.

Ono, Hiroshi; Matsumoto, Taro; Sasaki, Tomoyuki; Kawatsuki, Nobuhiro

2012-06-01

305

Distribution and Functions of TonB-Dependent Transporters in Marine Bacteria and Environments: Implications for Dissolved Organic Matter Utilization  

PubMed Central

Background Bacteria play critical roles in marine nutrient cycles by incorporating and redistributing dissolved organic matter (DOM) and inorganic nutrients in the ocean. TonB-dependent transporter (TBDT) proteins allow Gram-negative bacteria to take up scarce resources from nutrient-limiting environments as well as siderophores, heme, vitamin B12, and recently identified carbohydrates. Thus, the characterization of TBDT distribution and functions is essential to better understand the contribution TBDT to DOM assimilation and its consequences on nutrient cycling in the environment. Methodology/Principal Findings This study presents the distribution of encoded known and putative TBDT proteins in the genomes of microorganisms and from the Global Ocean Survey data. Using a Lek clustering algorithm and substrate specificities, the TBDT sequences were mainly classified into the following three groups: (1) DOM transporters; (2) Siderophores/Vitamins transporters; and (3) Heme/Hemophores/Iron(heme)-binding protein transporters. Diverse TBDTs were found in the genomes of oligotroph Citromicrobium bathyomarinum JL354 and Citromicrobium sp JLT1363 and were highly expressed in the stationary phase of bacterial growth. The results show that the Gammaproteobacteria and the Cytophaga-Flavobacterium-Bacteroides (CFB) group bacteria accounted for the majority of the TBDT gene pool in marine surface waters. Conclusions/Significance The results of this study confirm the ecological importance of TBDTs in DOM assimilation for bacteria in marine environments owing to a wide range of substrate utilization potential in the ubiquitous Gammaproteobacteria and CFB group bacteria. PMID:22829928

Tang, Kai; Jiao, Nianzhi; Liu, Keshao; Zhang, Yao; Li, Shuhui

2012-01-01

306

Analysis of mutations that uncouple transport from phosphorylation in enzyme IIGlc of the Escherichia coli phosphoenolpyruvate-dependent phosphotransferase system.  

PubMed Central

Mutations that uncouple glucose transport from phosphorylation were isolated in plasmid-encoded Escherichia coli enzyme IIGlc of the phosphoenolpyruvate-dependent phosphotransferase system (PTS). The uncoupled enzymes IIGlc were able to transport glucose in the absence of the general phosphoryl-carrying proteins of the PTS, enzyme I and HPr, although with relatively low affinity. Km values of the uncoupled enzymes IIGlc for glucose ranged from 0.5 to 2.5 mM, 2 orders of magnitude higher than the value of normal IIGlc. Most of the mutant proteins were still able to phosphorylate glucose and methyl alpha-glucoside (a non-metabolizable glucose analog specific for IIGlc), indicating that transport and phosphorylation are separable functions of the enzyme. Some of the uncoupled enzymes IIGlc transported glucose with a higher rate and lower apparent Km in a pts+ strain than in a delta ptsHI strain lacking the general proteins enzyme I and HPr. Since the properties of these uncoupled enzymes IIGlc in the presence of PTS-mediated phosphoryl transfer resembled those of wild-type IIGlc, these mutants appeared to be conditionally uncoupled. Sequencing of the mutated ptsG genes revealed that all amino acid substitutions occurred in a hydrophilic segment within the hydrophobic N-terminal part of IIGlc. These results suggest that this hydrophilic loop is involved in binding and translocation of the sugar substrate. Images PMID:1569016

Ruijter, G J; van Meurs, G; Verwey, M A; Postma, P W; van Dam, K

1992-01-01

307

Temperature-dependent gas transport performance of vertically aligned carbon nanotube/parylene composite membranes  

NASA Astrophysics Data System (ADS)

A novel composite membrane consisting of vertically aligned carbon nanotubes (CNTs) and parylene was successfully fabricated. Seamless filling of the spaces in CNT forests with parylene was achieved by a low-pressure chemical vapor deposition (CVD) technique and followed with the Ar/O2 plasma etching to expose CNT tips. Transport properties of various gases through the CNT/parylene membranes were explored. And gas permeances were independent on feed pressure in accordance with the Knudsen model, but the permeance values were over 60 times higher than that predicted by the Knudsen diffusion kinetics, which was attributed to specular momentum reflection inside smooth CNT pores. Gas permeances and enhancement factors over the Knudsen model firstly increased and then decreased with rising temperature, which confirmed the existence of non-Knudsen transport. And surface adsorption diffusion could affect the gas permeance at relatively low temperature. The gas permeance of the CNT/parylene composite membrane could be improved by optimizing operating temperature.

Zhang, Lei; Yang, Junhe; Wang, Xianying; Zhao, Bin; Zheng, Guangping

2014-08-01

308

Loading-Dependent Transport Properties of Zeolitic Imidazolate Frameworks Probed by In-Situ PFG NMR  

NASA Astrophysics Data System (ADS)

Zeolitic imidazolate frameworks (ZIFs), a unique subclass of metal-organic frameworks (MOFs) recently reported by Yaghi group and others, are attracting worldwide attention. Our systematic work on the adsorption and molecular transport in ZIFs has revealed some unique properties of these new materials that could not have been anticipated from standard structural characterization results. More specifically, the rearrangement of the imidazolate linkers (and in some cases, the framework structure) driven by adsorbate-adsorbent interaction causes the window sizes and accessible pore space of ZIFs to deviate (in some cases, drastically) from the values determined by low-temperature single-crystal X-ray crystallography and typical physisorption experiments carried out at liquid nitrogen temperature (77 K) with H2, N2 and Ar. Here we show the high degree of structural flexibility of ZIFs at near ambient temperatures and report the first time their unique adsorption and transport characteristics.

Kortunov, Pavel; Ni, Zheng; Paur, Charanjit; Reyes, Sebastian; Zengel, John

2011-03-01

309

SUMOylation-Dependent LRH-1/PROX1 Interaction Promotes Atherosclerosis by Decreasing Hepatic Reverse Cholesterol Transport.  

PubMed

Reverse cholesterol transport (RCT) is an antiatherogenic process in which excessive cholesterol from peripheral tissues is transported to the liver and finally excreted from the body via the bile. The nuclear receptor liver receptor homolog 1 (LRH-1) drives expression of genes regulating RCT, and its activity can be modified by different posttranslational modifications. Here, we show that atherosclerosis-prone mice carrying a mutation that abolishes SUMOylation of LRH-1 on K289R develop less aortic plaques than control littermates when exposed to a high-cholesterol diet. The mechanism underlying this atheroprotection involves an increase in RCT and its associated hepatic genes and is secondary to a compromised interaction of LRH-1 K289R with the corepressor prospero homeobox protein 1 (PROX1). Our study reveals that the SUMOylation status of a single nuclear receptor lysine residue can impact the development of a complex metabolic disease such as atherosclerosis. PMID:25176150

Stein, Sokrates; Oosterveer, Maaike H; Mataki, Chikage; Xu, Pan; Lemos, Vera; Havinga, Rick; Dittner, Claudia; Ryu, Dongryeol; Menzies, Keir J; Wang, Xu; Perino, Alessia; Houten, Sander M; Melchior, Frauke; Schoonjans, Kristina

2014-10-01

310

Temperature-dependent gas transport performance of vertically aligned carbon nanotube/parylene composite membranes  

PubMed Central

A novel composite membrane consisting of vertically aligned carbon nanotubes (CNTs) and parylene was successfully fabricated. Seamless filling of the spaces in CNT forests with parylene was achieved by a low-pressure chemical vapor deposition (CVD) technique and followed with the Ar/O2 plasma etching to expose CNT tips. Transport properties of various gases through the CNT/parylene membranes were explored. And gas permeances were independent on feed pressure in accordance with the Knudsen model, but the permeance values were over 60 times higher than that predicted by the Knudsen diffusion kinetics, which was attributed to specular momentum reflection inside smooth CNT pores. Gas permeances and enhancement factors over the Knudsen model firstly increased and then decreased with rising temperature, which confirmed the existence of non-Knudsen transport. And surface adsorption diffusion could affect the gas permeance at relatively low temperature. The gas permeance of the CNT/parylene composite membrane could be improved by optimizing operating temperature.

2014-01-01

311

Transverse Dynamics of the Azimuthally Inhomogeneous Electron Bunch in a Multilayer Dielectric Cylindrical Waveguide  

NASA Astrophysics Data System (ADS)

In reference [1], a complete analytical solution for Cherenkov wakefields generated by an azimuthally asymmetric annular beam propagating in a coaxial two-channel dielectric structure was presented. A drive bunch generates Cherenkov radiation (wakefield) inside the dielectric loaded waveguide and a second (witness) bunch passing through the structure at an appropriate delay with respect to the drive bunch is accelerated by the wakefield. Use of a ring beam in a multi-layer waveguide can significantly increase the transformer ratio by providing different paths for the ring driver and the accelerated bunch to pass through the structure. The main challenge of this scheme originates in the transverse dynamics of the drive bunch because of its high charge and relatively low energy. To hold the inner dielectric tube inside the waveguide metal (titanium) threads are used. The threads are located inside the drive beam section of the waveguide that leads to the segmentation of the drive beam. In this paper, we study the transverse dynamics of the annular beam with various types of azimuthally asymmetries that depend on the specifics of the beam generation and multilayer waveguide parameters. The different types of beam asymmetry and hybrid mode dependencies are presented using the original BBU-3000 [7] beam dynamics code.

Altmark, A. M.; Kanareykin, A. D.

2014-05-01

312

Solute transport in porous media with scale-dependent dispersion and periodic boundary conditions  

Microsoft Academic Search

An analytic solution is derived for the one-dimensional equations governing the transport of a tracer in a heterogeneous porous medium subject to rate-limited adsorption with a linear equilibrium isotherm, and also subject to decay. The kinetics of solute adsorption is given by a first-order rate law. The medium is semi-infinite, and periodic boundary conditions are imposed at the inlet boundary.

J. David Logan

1996-01-01

313

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

Microsoft Academic Search

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

ATSUSHI YOKOTA; MARLOES VEENSTRA; PETER KURDI; HENDRIK W. VAN VEEN; WIL N. KONINGS

2000-01-01

314

Growth atmosphere dependence of transport properties of NiO epitaxial thin films  

Microsoft Academic Search

Recent possible applications in nonvolatile resistive switching memory devices renewed the interests in the transport properties of NiO. The variation on the conductivities of NiO films was reported to strongly affect the resistive switching phenomena. The conduction mechanism of NiO has been interpreted in terms of the bulk p-type conduction mechanism via Ni deficiencies (Ni1-deltaO). Here we investigate the growth

Keisuke Oka; Takeshi Yanagida; Kazuki Nagashima; Hidekazu Tanaka; Tomoji Kawai

2008-01-01

315

Two-path transport measurements with bias dependence on a triple quantum dot  

SciTech Connect

We present transport measurements on a lateral triple quantum dot with a star-like geometry and one lead attached to each dot. The system is studied in a regime close to established quadruple points, where all three dots are in resonance. The specific sample structure allows us to apply two different bias voltages to the two source leads and thus to study the influence between the paths with serial double dots.

Kotzian, M.; Rogge, M. C.; Haug, R. J. [Institut für Festkörperphysik, Leibniz Universität Hannover, Appelstr. 2, 30167 Hannover (Germany)

2013-12-04

316

Dependence of the electronic transport on the microstructure in annealed Bi thin films  

NASA Astrophysics Data System (ADS)

Bi thin films, with a thickness ranging from 10 to 100 nm, are deposited by electron-beam evaporation on a thermally oxidized Si(100) substrate. The deposition parameters are optimized in order to maximize the grain size of the polycrystalline films. The evolution of the crystal orientation is examined as a function of the deposition and annealing parameters, by electron back scattering diffraction. Low temperature (21 mK - 150 K) magnetoresistance measurements (up to 15 T) on polycrystalline films reveal weak anti-localization, superimposed by the classical magnetoresistance. The analysis of the weak anti-localization allows us to extract quantum transport parameters, such as the phase coherence and the spin orbit coupling time. From the evolution of the broad magnetoresistance background, we infer the evolution of electronic transport parameters: the mobility, the charge carrier concentration and the mean free path. Magneto-transport and ab initio calculations are combined in order to investigate on the controversial existence of the semimetal-semiconductor transition.

Nhan Bui, Thanh; Raskin, Jean-Pierre; Malet, Loic; Godet, Stephane; Rodrigues Martins, Frederico; Faniel, Sebastien; Gonze, Xavier; Cabosart, Damien; Hackens, Benoit

2013-03-01

317

Time-dependent model of pollutant transport and diffusion in mountain valleys  

SciTech Connect

A new valley air-pollution model has been developed to predict short-term concentrations of nonreactive pollutant species on the valley floor and sidewalls resulting from a continuous elevated source located within a valley. The model was developed for use when the effects of local heating and cooling dominate the valley meteorology and the influence of synoptic circulations is weak. The physical processes acting to disperse pollutants during the nighttime steady-state period and the period of post-sunrise temperature inversion breakup are parameterized in modules within the model. The primary physical processes included in the model are nocturnal down-valley transport and enhanced diffusion of pollutants, plume channeling, plume dilution due to clean air flowing in from valley tributaries, and plume reflection from valley floor and sidewalls. Physical processes in the post-sunrise simulation include down-valley plume transport in the elevated remnant of the nocturnal temperature inversion, pollutant fumigation into growing convective boundary layers, subsidence in the valley atmosphere, and transport and diffusion of pollutants in upslope flows. This paper describes the physical processes incorporated in the model along with their parameterizations.

Whiteman, C.D.; Allwine, K.J.

1982-11-01

318

Transport of bare and capped zinc oxide nanoparticles is dependent on porous medium composition.  

PubMed

Zinc oxide (ZnO) nanoparticles are one of the most frequently used nanoparticles in industry and hence are likely to be introduced to the groundwater environment. The mobility of these nanoparticles in different aquifer materials has not been assessed. While some studies have been published on the transport of ZnO nanoparticles in individual porous media, these studies do not generally account for varying porous medium composition both within and between aquifers. As a first step towards understanding the impact of this variability, this paper compares the transport of bare ZnO nanoparticles (bZnO-NPs) and capped ZnO nanoparticles, coated with tri-aminopropyltriethoxysilane (cZnO-NPs), in saturated columns packed with glass beads, fine grained sand and fine grained calcite, at near-neutral pH and groundwater salinity levels. With the exception of cZnO-NPs in sand columns, ZnO nanoparticles are highly immobile in all three types of studied porous media, with most retention taking place near the column inlet. Results are in general agreement with DLVO theory, and the deviation in experiments with cZnO-NPs flowing through columns packed with sand is linked to variability in zeta potential of the capped nanoparticles and sand grains. Therefore, differences in surface charge of nanoparticles and porous media are demonstrated to be key drivers in nanoparticle transport. PMID:24796515

Kurlanda-Witek, H; Ngwenya, B T; Butler, I B

2014-07-01

319

Auxiliary quantization constraints on the von Roos ordering-ambiguity at zero binding energies; azimuthally symmetrized cylindrical coordinates  

E-print Network

Using azimuthally symmetrized cylindrical coordinates, we report the consequences of zero-energy quantal states on the von Roos Hamiltonian. A position-dependent mass M({\\rho},\\phi,z)=bz^{j}{\\rho}^{2\\u{psion}+1}/2 is used. We show that the zero-energy setting not only offers an additional degree of freedom towards feasible separability for the von Roos Hamiltonian, but also manifestly yields auxiliary quantized ambiguity parametric constraints.

Omar Mustafa

2011-08-29

320

Synthetic aperture radar range - Azimuth ambiguity design and constraints  

NASA Technical Reports Server (NTRS)

Problems concerning the design of a system for mapping a planetary surface with a synthetic aperture radar (SAR) are considered. Given an ambiguity level, resolution, and swath width, the problems are related to the determination of optimum antenna apertures and the most suitable pulse repetition frequency (PRF). From the set of normalized azimuth ambiguity ratio curves, the designer can arrive at the azimuth antenna length, and from the sets of normalized range ambiguity ratio curves, he can arrive at the range aperture length or pulse repetition frequency. A procedure based on this design method is shown in an example. The normalized curves provide results for a SAR using a uniformly or cosine weighted rectangular antenna aperture.

Mehlis, J. G.

1980-01-01

321

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

322

NSOM tips as subwavelength sources for azimuthally polarized light  

E-print Network

The aim of near-field scanning optical microscopy (NSOM) is to reveal the distribution of the electromagnetic field around nanoscale objects. The full vectorial nature of this field is more difficult to measure than just its amplitude. It can only be fully reconstructed with exact knowledge of the optical properties of the probe. Here, we report and numerically explain that NSOM tips with a well-defined apex diameter selectively support azimuthally polarized light (|$E_{\\text{azi}}$|$^2$/|$E_{\\text{tot}}$|$^2$ $\\approx$ 55$\\,$% $\\pm $ 5$\\,$% for 1.4$\\,$\\mu m tip aperture diameter and \\lambda$_0$ = 1550$\\,$nm). We attribute the generation of azimuthal polarization in the metal-coated fiber tip to symmetry breaking in the bend and subsequent plasmonic mode filtering in the truncated conical taper.

Ploss, Daniel; Pfeifer, Hannes; Banzer, Peter; Peschel, Ulf

2014-01-01

323

Maximizing Solar Energy Capture Through Multi-Azimuth PV Arrays  

NASA Astrophysics Data System (ADS)

By orienting photovoltaic (PV) arrays in multiple directions, significantly greater energy capture can be realized in high latitude locations. Conventional wisdom dictates orienting PV panels south (in the northern hemisphere), but multi-azimuth arrays can confer several advantages during the summer months: - Nearly even power production over a large part of the day (20+ hours) - Reduced issues with power quality in grid interactive systems - Support higher loads in independent, off-grid systems - Reduced energy storage (battery) requirements in off-grid systems This poster will present two multi-azimuth systems, one a grid-interactive system deployed at Summit Station, Greenland; the second an independent, off-grid system supporting a science project near Toolik Field Station, Alaska.

Dahl, T. S.

2013-12-01

324

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

325

Azimuthal asymmetry of the coherent backscattering cone: Theoretical results  

NASA Astrophysics Data System (ADS)

The azimuthal asymmetry of the polarized backscattering cone and the intimately related polarization opposition effect (POE) are corollaries of the theory of coherent backscattering (CB) valid in the asymptotic limit of very small particle packing density. In this paper we use numerically exact solutions of the Maxwell equations to study the evolution of these and other manifestations of CB as the packing density in a multiparticle group increases from zero to values typical of actual particle suspensions and particulate surfaces. Our results reveal a remarkable robustness of virtually all effects predicted by the low-density concept of CB and allow us to conclude that the azimuthal asymmetry and POE observed in the laboratory for densely packed discrete random media are indeed caused by CB.

Mishchenko, Michael I.; Dlugach, Janna M.; Liu, Li

2009-11-01

326

Azimuthal and Single Spin Asymmetries in Hard Scattering Processes  

E-print Network

In this article we review the present understanding of azimuthal and single spin asymmetries for inclusive and semi-inclusive particle production in unpolarized and polarized hadronic collisions at high energy and moderately large transverse momentum. After summarizing the experimental information available, we discuss and compare the main theoretical approaches formulated in the framework of perturbative QCD. We then present in some detail a generalization of the parton model with inclusion of spin and intrinsic transverse momentum effects. In this context, we extensively discuss the phenomenology of azimuthal and single spin asymmetries for several processes in different kinematical configurations. A comparison with the predictions of other approaches, when available, is also given. We finally emphasize some relevant open points and challenges for future theoretical and experimental investigation.

U. D'Alesio; F. Murgia

2007-12-28

327

Azimuthal B?D*?-? ¯? angular distribution with tensor operators  

NASA Astrophysics Data System (ADS)

In a recent paper we performed a comprehensive study of the impact of new-physics operators with different Lorentz structures on B ¯?D*+l-?? ¯ decays, ?=e-, ?-, ?-, involving the b?cl?? transition. In this work we extend the previous calculation by including tensor operators. In the case of B ¯?D*+?-?? ¯, we present the full three-angle and q2 angular distribution with tensor new-physics operators with complex couplings. The impact of the tensor operators on various observables in the angular distribution, specially the azimuthal observables including the CP violating triple product asymmetries are discussed. It is shown that these azimuthal observables are very useful in discriminating different new-physics operators. Finally we consider new-physics leptoquark models with tensor interactions and show how the presence of additional scalar operators modify the predictions of the tensor operators.

Duraisamy, Murugeswaran; Sharma, Preet; Datta, Alakabha

2014-10-01

328

Generic framework for anisotropic flow analyses with multiparticle azimuthal correlations  

NASA Astrophysics Data System (ADS)

We present a new generic framework which enables exact and efficient evaluation of all multiparticle azimuthal correlations. The framework can be readily used along with a correction framework for systematic biases in anisotropic flow analyses owing to various detector inefficiencies. A new recursive algorithm has been developed for higher-order correlators for the cases where their direct implementation is not feasible. We propose and discuss new azimuthal observables for anisotropic flow analyses which can be measured for the first time with our new framework. The effect of finite detector granularity on multiparticle correlations is quantified and discussed in detail. We point out the existence of a systematic bias in traditional differential flow analyses which stems solely from the applied selection criteria on particles used in the analyses and is also present in the ideal case when only flow correlations are present. Finally, we extend the applicability of our generic framework to the case of differential multiparticle correlations.

Bilandzic, Ante; Christensen, Christian Holm; Gulbrandsen, Kristjan; Hansen, Alexander; Zhou, You

2014-06-01

329

Magnetotelluric inversion for azimuthally anisotropic resistivities employing artificial neural networks  

NASA Astrophysics Data System (ADS)

An extension of an artificial neural network (ANN) approach to solve the magnetotelluric (MT) inverse problem for azimuthally anisotropic resistivities is presented and applied for a real dataset. Three different model classes, containing general 1-D and 2-D azimuthally anisotropic features, have been considered. For each model class, characteristics of three-layer feed forward ANNs trained through an error back propagation algorithm have been adjusted to approximate the inverse modeling function. It appears that, at least for synthetic models, reasonable results would be obtained by applying the amplitudes of the complex impedance tensor elements as inputs. Furthermore, the Levenberg-Marquart algorithm possesses optimal performance as a learning paradigm for this problem. The evaluation of applicability of the trained ANNs for unknown data sets excluded from the learning procedure reveals that the trained ANNs possess acceptable interpolation and extrapolation abilities to estimate model parameters accurately. This method was also successfully used for a field dataset wherein anisotropy had been previously recognized.

Montahaei, Mansoure; Oskooi, Behrooz

2014-02-01

330

Temperature-dependent ballistic transport in a channel with length below the scattering-limited mean free path  

NASA Astrophysics Data System (ADS)

The temperature-dependent ballistic transport, using nonequilibrium Arora distribution function (NEADF), is shown to result in mobility degradation with reduction in channel length, in direct contrast to expectation of a collision-free transport. The ballistic mean free path (mfp) is much higher than the scattering-limited long-channel mfp, yet the mobility is amazingly lower. High-field effects, converting stochastic velocity vectors to streamlined ones, are found to be negligible when the applied voltage is less than the critical voltage appropriate for a ballistic mfp, especially at cryogenic temperatures. Excellent agreement with the experimental data on a metal-oxide-semiconductor field-effect transistor is obtained. The applications of NEADF are shown to cover a wide spectrum, covering regimes from the scattering-limited to ballistic, from nondegenerate to degenerate, from nanowire to bulk, from low- to high-temperature, and from a low electric field to an extremely high electric field.

Arora, Vijay K.; Zainal Abidin, Mastura Shafinaz; Tan, Michael L. P.; Riyadi, Munawar A.

2012-03-01

331

Temperature dependent transport and photoresponse properties of a Mn-doped ZnO/p-Si heterojunction  

NASA Astrophysics Data System (ADS)

A Mn-doped ZnO (ZMO) thin film was deposited on a p-Si (100) substrate by magnetron sputtering technology. The structure and morphology of the film were tested by x-ray diffraction and atomic force microscopy. The temperature dependent transport and photoresponse properties of the ZMO/Si heterojunction were also investigated. Results show that the ZMO film was successfully deposited in the polycrystalline structure with a smooth and crack-free surface. The current-voltage (I-V) curves show that the heterojunction exhibits excellent rectifying behavior. As temperature is decreased, the ideality factor of the heterojunction becomes remarkably large, implying a significant change of transport mechanism with differing temperatures. Photocurrent can emerge by illumination. Under reverse bias, the photocurrent increases drastically with the increase of reverse bias and then becomes saturated beyond a certain voltage. In addition, the critical voltage increases with the increase of temperature.

Zhao, C. W.; Xing, H.; Chen, C. L.; Y Wang, J.; Dong, X. L.; Zhang, R. L.; Jin, K. X.

2014-04-01

332

Edge contact dependent spin transport for n-type doping zigzag-graphene with asymmetric edge hydrogenation  

PubMed Central

Spin transport features of the n-type doping zigzag graphene nanoribbons (ZGNRs) with an edge contact are investigated by first principle methods, where ZGNRs are C–H2 bonded at one edge while C–H bonded at the other to form an asymmetric edge hydrogenation. The results show that a perfect spin filtering effect (100%) in such ZGNR nanojunctions can be achieved in a very large bias region for the unchanged spin states regardless of bias polarities, and the nanojunction with a contact of two C–H2 bonded edges has larger spin polarized current than that with a contact of two C–H bonded edges. The transmission pathways and the projected density of states (PDOS) demonstrate that the edge of C-H2 bonds play a crucial role for the spin magnetism and spin-dependent transport properties. Moreover, the negative differential resistance (NDR) effect is also observed in the spin-polarized current. PMID:24509476

Deng, Xiaoqing; Zhang, Zhenhua; Tang, Guiping; Fan, Zhiqiang; Zhu, Huali; Yang, Changhu

2014-01-01

333

Spin-dependent transport behavior in C60 and Alq3 based spin valves with a magnetite electrode (invited)  

NASA Astrophysics Data System (ADS)

The spin-dependent transport behavior in organic semiconductors (OSs) is generally observed at low temperatures, which likely results from poor spin injection efficiency at room temperature from the ferromagnetic metal electrodes to the OS layer. Possible reasons for this are the low Curie temperature and/or the small spin polarization efficiency for the ferromagnetic electrodes used in these devices. Magnetite has potential as an advanced candidate for use as the electrode in spintronic devices, because it can achieve 100% spin polarization efficiency in theory, and has a high Curie temperature (850 K). Here, we fabricated two types of organic spin valves using magnetite as a high efficiency electrode. C60 and 8-hydroxyquinoline aluminum (Alq3) were employed as the OS layers. Magnetoresistance ratios of around 8% and over 6% were obtained in C60 and Alq3-based spin valves at room temperature, respectively, which are two of the highest magnetoresistance ratios in organic spin valves reported thus far. The magnetoresistance effect was systemically investigated by varying the thickness of the Alq3 layer. Moreover, the temperature dependence of the magnetoresistance ratios for C60 and Alq3-based spin valves were evaluated to gain insight into the spin-dependent transport behavior. This study provides a useful method in designing organic spin devices operated at room temperature.

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

2014-05-01

334

AN AZIMUTHAL ASYMMETRY IN THE LkH? 330 DISK  

SciTech Connect

Theory predicts that giant planets and low mass stellar companions shape circumstellar disks by opening annular gaps in the gas and dust spatial distribution. For more than a decade it has been debated whether this is the dominant process that leads to the formation of transitional disks. In this paper, we present millimeter-wave interferometric observations of the transitional disk around the young intermediate mass star LkH? 330. These observations reveal a lopsided ring in the 1.3 mm dust thermal emission characterized by a radius of about 100 AU and an azimuthal intensity variation of a factor of two. By comparing the observations with a Gaussian parametric model, we find that the observed asymmetry is consistent with a circular arc, that extends azimuthally by about 90° and emits about 1/3 of the total continuum flux at 1.3 mm. Hydrodynamic simulations show that this structure is similar to the azimuthal asymmetries in the disk surface density that might be produced by the dynamical interaction with unseen low mass companions orbiting within 70 AU from the central star. We argue that such asymmetries might lead to azimuthal variations in the millimeter-wave dust opacity and in the dust temperature, which will also affect the millimeter-wave continuum emission. Alternative explanations for the observed asymmetry that do not require the presence of companions cannot be ruled out with the existing data. Further observations of both the dust and molecular gas emission are required to derive firm conclusions on the origin of the asymmetry observed in the LkH? 330 disk.

Isella, Andrea; Carpenter, John M.; Ricci, Luca [Department of Astronomy, California Institute of Technology, MC 249-17, Pasadena, CA 91125 (United States); Pérez, Laura M. [Jansky Fellow, National Radio Astronomy Observatory, Socorro, NM (United States); Andrews, Sean; Rosenfeld, Katherine, E-mail: isella@astro.caltech.edu [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)

2013-09-20

335

Analysis of azimuthal mode dynamics of mesoscale eddies  

E-print Network

decomposition technique has been developed by which eddy property patterns can be decomposed into radial and azimuthal modal components. The coeffi- cients of the decomposition are then used to calculate the potential energy and approximate kinetic energy.... TABLE OF CONTENTS CHAPTER I. INTRODUCTION a. Previous Observations b. Laboratory Experiments c. Analytical Studies d. Numerical Simulations e . Modal Decomposition CHAPTER II. MATHEMATICAL METHOD a . Selection of Basis Functions b. Orthogonality...

McCalpin, John David

2012-06-07

336

The azimuthal critical state of a superconducting hollow cylinder  

Microsoft Academic Search

We use the critical state model to calculate the flux profiles and magnetization curves for type II superconducting hollow cylinders of different wall thicknesses subject to an azimuthal magnetic field produced by a coaxially arranged current-carrying wire. We analyze the cases of field-independent and field-decaying critical current densities, and systematically compare the results with those expected for the “conventional” slab

E. Altshuler; R. Mulet

1997-01-01

337

Azimuthal clumping instabilities in a Z-pinch wire array  

SciTech Connect

A simple model is constructed to evaluate the temporal evolution of azimuthal clumping instabilities in a cylindrical array of current-carrying wires. An analytic scaling law is derived, which shows that randomly seeded perturbations evolve at the rate of the fastest unstable mode, almost from the start. This instability is entirely analogous to the Jeans instability in a self-gravitating disk, where the mutual attraction of gravity is replaced by the mutual attraction among the current-carrying wires.

Strickler, Trevor; Lau, Y.Y.; Gilgenbach, R.M.; Cuneo, M.E.; Mehlhorn, T.A. [Department of Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, Michigan 48109-2104 (United States)

2005-05-15

338

An Azimuthal Asymmetry in the LkH? 330 Disk  

NASA Astrophysics Data System (ADS)

Theory predicts that giant planets and low mass stellar companions shape circumstellar disks by opening annular gaps in the gas and dust spatial distribution. For more than a decade it has been debated whether this is the dominant process that leads to the formation of transitional disks. In this paper, we present millimeter-wave interferometric observations of the transitional disk around the young intermediate mass star LkH? 330. These observations reveal a lopsided ring in the 1.3 mm dust thermal emission characterized by a radius of about 100 AU and an azimuthal intensity variation of a factor of two. By comparing the observations with a Gaussian parametric model, we find that the observed asymmetry is consistent with a circular arc, that extends azimuthally by about 90° and emits about 1/3 of the total continuum flux at 1.3 mm. Hydrodynamic simulations show that this structure is similar to the azimuthal asymmetries in the disk surface density that might be produced by the dynamical interaction with unseen low mass companions orbiting within 70 AU from the central star. We argue that such asymmetries might lead to azimuthal variations in the millimeter-wave dust opacity and in the dust temperature, which will also affect the millimeter-wave continuum emission. Alternative explanations for the observed asymmetry that do not require the presence of companions cannot be ruled out with the existing data. Further observations of both the dust and molecular gas emission are required to derive firm conclusions on the origin of the asymmetry observed in the LkH? 330 disk.

Isella, Andrea; Pérez, Laura M.; Carpenter, John M.; Ricci, Luca; Andrews, Sean; Rosenfeld, Katherine

2013-09-01

339

Modal Testing and FE-model Validation of Azimuthing Thruster  

Microsoft Academic Search

\\u000a Vibratory behavior of an azimuthing thruster was studied with FE-models and the results were verified by full-scale experiments.\\u000a Studied thruster systems are used both for main propulsion and for steering of vessels. Modeling techniques were developed\\u000a to take into account the most significant factors and phenomena affecting on the vibration behavior of the structure in real\\u000a operation conditions. Modeling of

Vesa Nieminen; Matti Tervonen

340

The hepatobiliary disposition of timosaponin b2 is highly dependent on influx/efflux transporters but not metabolism.  

PubMed

The purpose of this study was to characterize the hepatobiliary disposition of timosaponin B2 (TB-2), a natural saponin. Although TB-2 has multiple pharmacologic activities, the mechanism of its hepatobiliary disposition has not been explored. Because the metabolism of TB-2 is limited and the accumulation of TB-2 in primary hepatocytes is highly temperature dependent (93% of its accumulation is due to active uptake), the contribution of hepatic transporters was investigated. Organic anion-transporting polypeptide (OATP) 1B1- and OATP1B3-transfected human embryonic kidney 293 cells were employed. TB-2 serves as a substrate for OATP1B1 and OATP1B3, with the former playing a predominant role in the hepatic uptake of TB-2. An inhibition study in sandwich-cultured rat hepatocytes suggested that TB-2 is a substrate for both breast cancer resistance protein (Bcrp) and multidrug resistance-associated protein 2 (Mrp2), consistent with its high biliary excretion index (43.1-44.9%). This hypothesis was further verified in BCRP and MRP2 membrane vesicles. The cooperation of uptake and efflux transporters in TB-2 hepatic disposition could partially explain the double-peak phenomenon observed in rat plasma and liver and biliary clearance, which accounted for 70% of the total TB-2 clearance. Moreover, TB-2 significantly increased the rosuvastatin concentration in rat plasma in a concentration-dependent manner and decreased its biliary excretion, which corresponded to reductions in rosuvastatin accumulation in hepatocytes and the biliary excretion index in sandwich-cultured rat hepatocytes, representing a perfect example of a potential saponin-statin drug-drug interaction. These studies demonstrate that transporters (Oatp, Bcrp/Mrp2), but not metabolism, contribute significantly to rat TB-2 hepatobiliary disposition. PMID:25336752

Sheng, Jingjing; Tian, Xiaoting; Xu, Guanglin; Wu, Zhitao; Chen, Chen; Wang, Le; Pan, Lili; Huang, Chenggang; Pan, Guoyu

2015-01-01

341

Crack azimuths on Europa: The G1 lineament sequence revisited  

USGS Publications Warehouse

The tectonic sequence in the anti-jovian area covered by regional mapping images from Galileo's orbit E15 is determined from a study of cross-cutting relationships among lineament features. The sequence is used to test earlier results from orbit G1, based on lower resolution images, which appeared to display a progressive change in azimuthal orientation over about 90?? in a clockwise sense. Such a progression is consistent with expected stress variations that would accompany plausible non-synchronous rotation. The more recent data provide a more complete record than the G1 data did. We find that to fit the sequence into a continual clockwise change of orientation would require at least 1000?? (> 5 cycles) of azimuthal rotation. If due to non-synchronous rotation of Europa, this result implies that we are seeing back further into the tectonic record than the G1 results had suggested. The three sets of orientations found by Geissler et al. now appear to have been spaced out over several cycles, not during a fraction of one cycle. While our more complete sequence of lineament formation is consistent with non-synchronous rotation, a statistical test shows that it cannot be construed as independent evidence. Other lines of evidence do support non-synchronous rotation, but azimuths of crack sequences do not show it, probably because only a couple of cracks form in a given region in any given non-synchronous rotation period. ?? 2004 Elsevier Inc. All rights reserved.

Sarid, A.R.; Greenberg, R.; Hoppa, G.V.; Brown, D.M., Jr.; Geissler, P.

2005-01-01

342

Study of flow factorization with two particle azimuthal correlation  

NASA Astrophysics Data System (ADS)

Elliptic flow (v2) provides information about initial expansion of the medium created in non-central heavy ion collisions. However non-flow effects, such as jet correlation, can contribute significantly to the measured v2. In this talk we investigate the possibility of separating flow and non-flow components of v2 (vn in general) measured via two particle azimuthal correlations. If the observed azimuthal anisotropy is due to global flow, then coefficients vn,n(pT^a, pT^b) in Fourier decomposition of two particle correlation function dN/d?? factorize into product of single particle flow coefficients: vn,n(pT^a, pT^b)) = vn(pT^a)vn(pT^b). Deviation from vn,n factorization indicates a significant non-flow contribution. We investigate the flow and non-flow contributions to two particle azimuthal correlations with model of heavy ions dynamics which includes particles from hydro medium (with a given anisotropic flow) and jet correlations simulated with Pythia. We discuss the feasibility of separation of flow and nonflow in the real data based on the hypothesis of vn,n factorization for a global flow.

Kikola, Daniel; Wang, Fuqiang

2011-10-01

343

Resolution dependence of cross-tropopause ozone transport over east Asia  

NASA Astrophysics Data System (ADS)

Detailed analysis of mesoscale transport of ozone across the tropopause over east Asia during the spring of 2001 is conducted using regional simulations with the University of Wisconsin Nonhydrostatic Modeling System (UWNMS), in situ flight data, and a new two-scale approach to diagnosing this ozone flux. From late February to early April, synoptic activity regularly deformed the tropopause, leading to observations of ozone-rich (concentration exceeding 80 ppbv) stratospheric intrusions and filaments at tropospheric altitudes. Since model resolution is generally not sufficient to capture detailed small-scale mixing processes, an upper bound on the flux is proposed by assuming that there exists a dynamical division by spatial scale, above which the wind conservatively advects large-scale structures, while below it the wind leads to irreversible transport through nonconservative random strain. A formulation for this diagnosis is given and applied to ozone flux across the dynamical tropopause. Simulations were chosen to correspond with DC-8 flight 15 on 26-27 March over east Asia during the Transport and Chemical Evolution Over the Pacific (TRACE-P) campaign. Local and domain-averaged flux values using this method agree with other numerical and observational studies in similar synoptic environments. Sensitivity to numerical resolution, prescribed divisional spatial scale, and potential vorticity (PV) level is investigated. Divergent residual flow in regions of high ozone, and PV gradients tended to maximize flux magnitudes. We estimated the domain-integrated flow of ozone out of the lowermost stratosphere to be about 0.127 Tg/day. Spectral analysis of the wind field lends support for utilization of this dynamical division in this methodology.

Büker, M. L.; Hitchman, Matthew H.; Tripoli, Gregory J.; Pierce, R. B.; Browell, E. V.; Avery, M. A.

2005-02-01

344

Dependence of spontaneous neuronal firing and depolarisation block on astroglial membrane transport mechanisms.  

PubMed

Exposed to a sufficiently high extracellular potassium concentration ([K(?+?)]?), the neuron can fire spontaneous discharges or even become inactivated due to membrane depolarisation ('depolarisation block'). Since these phenomena likely are related to the maintenance and propagation of seizure discharges, it is of considerable importance to understand the conditions under which excess [K(?+?)]? causes them. To address the putative effect of glial buffering on neuronal activity under elevated [K(?+?)](o) conditions, we combined a recently developed dynamical model of glial membrane ion and water transport with a Hodgkin-Huxley type neuron model. In this interconnected glia-neuron model we investigated the effects of natural heterogeneity or pathological changes in glial membrane transporter density by considering a large set of models with different, yet empirically plausible, sets of model parameters. We observed both the high [K(?+?)]?-induced duration of spontaneous neuronal firing and the prevalence of depolarisation block to increase when reducing the magnitudes of the glial transport mechanisms. Further, in some parameter regions an oscillatory bursting spiking pattern due to the dynamical coupling of neurons and glia was observed. Bifurcation analyses of the neuron model and of a simplified version of the neuron-glia model revealed further insights about the underlying mechanism behind these phenomena. The above insights emphasise the importance of combining neuron models with detailed astroglial models when addressing phenomena suspected to be influenced by the astroglia-neuron interaction. To facilitate the use of our neuron-glia model, a CellML version of it is made publicly available. PMID:21667153

Øyehaug, Leiv; Østby, Ivar; Lloyd, Catherine M; Omholt, Stig W; Einevoll, Gaute T

2012-02-01

345

Carrier generation, recombination, trapping, and transport in semiconductors with position-dependent composition. [in junction solar cells  

NASA Technical Reports Server (NTRS)

The spatial variation of the chemical composition of a semiconductor modifies the ideal one-electron energy band model as well as the Shockley equations for carrier recombination and transport in two important ways. The random component of the spatial variation introduces localized states in the energy gap by perturbing the band states. The nonrandom component gives rise to the position dependences of the conduction and valence band edges or the electron affinity and the energy gap. This paper gives the modifications of the Shockley equations from these two effects as well as an example of the steady-state recombination rate from distributed gap states in junction solar cells

Sah, C.-T.; Lindholm, F. A.

1977-01-01

346

Temperature dependence of the electrical transport properties in few-layer graphene interconnects.  

PubMed

We report a systematic investigation of the temperature dependence of electrical resistance behaviours in tri- and four-layer graphene interconnects. Nonlinear current-voltage characteristics were observed at different temperatures, which are attributed to the heating effect. With the resistance curve derivative analysis method, our experimental results suggest that Coulomb interactions play an essential role in our devices. The room temperature measurements further indicate that the graphene layers exhibit the characteristics of semiconductors mainly due to the Coulomb scattering effects. By combining the Coulomb and short-range scattering theory, we derive an analytical model to explain the temperature dependence of the resistance, which agrees well with the experimental results. PMID:23885802

Liu, Yanping; Liu, Zongwen; Lew, Wen Siang; Wang, Qi Jie

2013-01-01

347

Temperature dependence of the electrical transport properties in few-layer graphene interconnects  

PubMed Central

We report a systematic investigation of the temperature dependence of electrical resistance behaviours in tri- and four-layer graphene interconnects. Nonlinear current–voltage characteristics were observed at different temperatures, which are attributed to the heating effect. With the resistance curve derivative analysis method, our experimental results suggest that Coulomb interactions play an essential role in our devices. The room temperature measurements further indicate that the graphene layers exhibit the characteristics of semiconductors mainly due to the Coulomb scattering effects. By combining the Coulomb and short-range scattering theory, we derive an analytical model to explain the temperature dependence of the resistance, which agrees well with the experimental results. PMID:23885802

2013-01-01

348

Time-dependent quantum transport and nonquasistatic effects in carbon nanotube transistors  

NASA Astrophysics Data System (ADS)

Nonquasistatic effects in ac characteristics of carbon nanotube field-effect transistors are examined by solving a full time-dependent, open-boundary Schrödinger equation. The nonquasistatic characteristics, such as the finite channel charging time, and the dependence of small signal transconductance and gate capacitance on the frequency, are explored. The validity of the widely used quasistatic approximation is examined. The results show that the quasistatic approximation overestimates the transconductance and gate capacitance at high frequencies, but gives a more accurate value for the intrinsic cutoff frequency over a wide range of bias conditions.

Chen, Yupeng; Ouyang, Yijian; Guo, Jing; Wu, Thomas X.

2006-11-01

349

Azimuthal anisotropy layering and plate motion in the Pacific Ocean  

NASA Astrophysics Data System (ADS)

We recently developed a three dimensional radially and azimuthally anisotropic model of the upper mantle in north America, using a combination of long-period 3-component surface and overtone waveforms, and SKS splitting measurements (Yuan and Romanowicz, 2010, Yuan et al., 2011). We showed that azimuthal anisotropy is a powerful tool to detect layering in the upper mantle, revealing two domains in the cratonic lithosphere, separated by a sharp laterally varying boundary in the depth range 100-150 km, which seems to coincide with the mid-lithospheric boundary (MLD) found in receiver function studies. Contrary to receiver functions, azimuthal anisotropy also detects the lithosphere-asthenosphere boundary (LAB) as manifested by a change in the fast axis direction, which becomes quasi-parallel to the absolute plate motion below ~250 km depth. A zone of stronger azimuthal anisotropy is found below the LAB both in the western US (peaking at depths of 100-150km) and in the craton (peaking at a depth of about 300 km). Here we show preliminary attempts at expanding our approach to the global scale, with a specific goal of determining whether such an anisotropic LAB can also be observed in the Pacific ocean. We started with our most recent global upper mantle radially anisotropic shear velocity model, determined using the Spectral Element Method (SEMum2; French et al., this meeting). We augment the corresponding global surface wave and overtone dataset (period range 60 to 400 s) with deep events and shorter period body waves, in order to ensure optimal deeper depth (>250km) anisotropy recovery due to the paucity of shear wave splitting measurements in the oceans. Our preliminary results, which do not yet incorporate SKS splitting measurements, look promising as they confirm the layering found previously in North America, using a different, global dataset and starting model. In the Pacific, our study confirms earlier azimuthal anisotropy results in the region (e.g. Smith et al. 2004; Maggi et al. 2006) that the shallow upper mantle beneath the ocean basin is strongly stratified. Our results further illustrate that 1) a shallow anisotropy domain (~100 km) is present, which is high in velocity and has in general a northward anisotropy direction where the plate is old (>80 Ma); and 2) there is a deeper domain (100-200 km) with stronger anisotropy, which correlates spatially with the low velocity zone and has a fast axis direction in good agreement with the absolute plate motion direction (HS3 NUVEL-1A). The boundary between the anisotropy domains clearly follows the age progressive deepening of the fast velocity in the shallow domain, suggesting an oceanic LAB that separates the Pacific lithosphere and the underlying asthenosphere.

Yuan, H.; Romanowicz, B. A.

2012-12-01

350

Pressure dependence of fluid transport properties of shallow fault systems in the Nankai subduction zone  

NASA Astrophysics Data System (ADS)

We measured fluid transport properties at an effective pressure of 40 MPa in core samples of sediments and fault rocks collected by the Integrated Ocean Drilling Program (IODP) NanTroSEIZE drilling project Expedition 316 from the megasplay fault system (site C0004) and the frontal thrust (site C0007) in the Nankai subduction zone. Permeability decreased with effective pressure as a power law function. Permeability values in the fault zones were 8 × 10-18 m2 at site C0004 and 9 × 10-18 m2 at site C0007. Stratigraphic variation in transport properties suggests that the megasplay fault zone may act as a barrier to fluid flow, but the frontal thrust fault zone might not. Depth variation in permeability at site C0007 is probably controlled by the mechanical compaction of sediment. Hydraulic diffusivity at shallow depths was approximately 1 × 10-6 m2 s-1 in both fault zones, which is small enough to lead to pore pressure generation that can cause dynamic fault weakening. However, absence of a very low permeable zone, which may have formed in the Japan Trench subduction zone, might prevent facilitation of huge shallow slips during Nankai subduction zone earthquakes. Porosity tests under dry conditions might have overestimated the porosity.

Tanikawa, Wataru; Mukoyoshi, Hideki; Lin, Weiren; Hirose, Takehiro; Tsutsumi, Akito

2014-12-01

351

Dependence of growth temperature on carrier gas velocity in open tube transport  

NASA Astrophysics Data System (ADS)

The apparent supercooling ( ?T ? Ts - Te, where Ts is the saturation temperature and Te is the equilibr ium growth temperature) of ZnTe crystals was measured in an open tube transport experiment as a function of carrier gas velocity. For four growth tubes with diameters from 0.1 to 0.84 cm, a minimum in ? T of ˜ 0 °C is observed at a Reynolds number of about 50. At lower Reynolds numbers the temperatures required for nucleation and growth were as much as 100 °C below Ts, although it might have been expected that equilibrium would be approached most closely at the lowest gas velocities. At higher Reynolds numbers growth also occurs many degrees below Ts. On the other hand, crystals sometimes grow near the axis of the growth tube at temperatures above Ts. It is suggested that these unexpected results may be due to concentration gradients in the gas phase resulting from thermal diffusion of the heavier atoms and molecules to the cooler regions of the system. Whatever the explanation, the carrier gas velocity performs an important role in crystal growth by open tube transport.

Reed, T. B.; Lafleur, W. J.

1972-12-01

352

Temperature-Dependent Electron Transport in Si and Ge Nanoparticle Photovoltaics  

NASA Astrophysics Data System (ADS)

We have studied both Si and Ge nanoparticle-based photovoltaic (PV) devices fabricated in a layered structure via spin-coating of the colloidal Si or Ge solution. With the low toxicity and high abundance of these group IV elements, combined with the relatively low costs of manufacturing via solution deposition, large-scale device processing offers high dollar-per-Watt opportunities as efficiencies continue to improve. To that end, we previously reported temperature effects of solution-processed PbS quantum dot (QD) PVs, wherein the capping ligand's thermal properties were shown to have strong effects on device performance. Here we show similar ligand effects in group IV QD devices. Current-voltage (I-V) measurements at temperatures from 100 to 360 K under dark conditions were fit to the ideal diode equation revealing the electron transport mechanism, with fit parameters matching transport models. The illuminated I-V data provide insight into each device's built-in potential, carrier mobility, and activation energy. In addition, modulating the illumination intensity gives the ideality factors of the solar cells. We show how these variations with temperature and light-intensity can be used to increase device performance for future studies.

Padilla, Derek; Church, Carena; Muthuswamy, Elayaraja; Kauzlarich, Susan; Carter, Sue

2013-03-01

353

Challenging the utility of third-order azimuth harmonics in the description of ultrarelativistic heavy-ion collisions  

NASA Astrophysics Data System (ADS)

In recent years it has become conventional practice to include higher-order cylindrical harmonics in the phenomenological description of two-particle angular correlations from ultra-relativistic heavy-ion collisions. These model elements, whose dependence on relative azimuth angle has the form cos[m(?1-?2)], where m>2, were introduced to support a hydrodynamic flow interpretation of the same-side (|?1-?2|2 harmonics are not required by the data, that they destabilize the fitting models, and that their net effect is to decompose the same-side peak into two components, one being dependent on and the other being independent of relative pseudorapidity. Thus, we are led to question whether descriptions of angular correlation data including higher-order harmonics inform our understanding of the same-side peak or heavy-ion collisions in general. Results from analysis of two-dimensional angular correlation data from the Relativistic Heavy-Ion Collider (RHIC) and the Large Hadron Collider show that the RHIC data do not exclude a single-Gaussian hypothesis for the same-side peak. We find that the net effect of including the m=3 harmonic or azimuth sextupole in the fitting model is the inclusion of small non-Gaussian dependence in the mathematical description of the same-side peak. Those non-Gaussian effects are systematically insignificant and can be accommodated by minor perturbations to the same-side 2D Gaussian peak model, which act locally at small relative azimuth. We also demonstrate that the 0%-1% 2D angular correlation data for 2.76-TeV Pb+Pb collisions from ATLAS, which display an away-side double peak on azimuth, do not require a sextupole, and exclude a positive same-side sextupole.

Ray, R. L.; Prindle, D. J.; Trainor, T. A.

2013-10-01

354

Low dopamine transporter occupancy by methylphenidate as a possible reason for reduced treatment effectiveness in ADHD patients with cocaine dependence.  

PubMed

Methylphenidate (MPH) occupies brain striatal dopamine transporters (DATs) and is an effective treatment for attention deficit hyperactivity disorder (ADHD). However, patients with ADHD and comorbid cocaine dependence do not benefit significantly from treatment with MPH. To better understand the neurobiology of this phenomenon, we examined DAT availability and the effects of MPH treatment on DAT occupancy in ADHD patients with and without cocaine dependence. ADHD patients without a comorbid substance use disorder (N=16) and ADHD patients with comorbid cocaine dependence (N=8) were imaged at baseline and after two weeks MPH treatment using single photon emission computed tomography (SPECT) with the DAT tracer [(123)I]FP-CIT. Changes in ADHD symptoms were measured with the ADHD symptom rating scale (ASRS). At baseline, we observed lower striatal DAT availability in ADHD patients with cocaine dependence. Following fixed MPH treatment, MPH occupied significantly less striatal DATs in cocaine-dependent than in non-cocaine dependent ADHD patients. There were no significant correlations between baseline DAT availability or DAT occupancy by MPH and ADHD symptom improvement. However, we did find significant correlations between DAT occupancy by MPH and decreases in impulsivity scores and years of cocaine use. These preliminary findings suggest that low DAT occupancy is not the reason why ADHD patients with cocaine dependence do not benefit from MPH treatment. It also suggests that higher dosages of MPH in these patients are probably not the solution and that medications directed at other pharmacological targets should be considered in these comorbid ADHD patients. This trial is registered at the Dutch Trial Register, www.trialregister.nl, under Trial ID number NTR3127. PMID:23731497

Crunelle, Cleo L; van den Brink, Wim; Veltman, Dick J; van Emmerik-van Oortmerssen, Katelijne; Dom, Geert; Schoevers, Robert A; Booij, Jan

2013-12-01

355

Frequency-dependent Monte Carlo simulations of phonon transport in two-dimensional porous silicon with aligned pores  

NASA Astrophysics Data System (ADS)

In this work, phonon transport in two-dimensional (2D) porous silicon structures with aligned pores is investigated by Monte Carlo simulations considering the frequency-dependent phonon mean free paths (MFPs). A boundary condition based on the periodic heat flux with constant virtual wall temperature is developed for the studied periodic structures. Such periodic boundary conditions enable the simulation of the lattice thermal conductivities with a minimum computational domain. For the 2D case, it is found that phonon size effects caused by the periodically arranged pores can be remarkable even when the pore size and spacing are much larger than the averaged phonon MFPs. Our results show the importance of considering the frequency dependence of phonon MFPs in the analysis of micro- and nanostructured materials.

Hao, Qing; Chen, Gang; Jeng, Ming-Shan

2009-12-01

356

Transport across a pinned domain wall across a GaMnAs constriction: from AMR to spin-dependent tunneling.  

NASA Astrophysics Data System (ADS)

We report on the different magnetotransport mechanism across a pinned domain wall in a GaMnAs nanowire dependent on constriction size. Nanometer-sized constrictions are realized in LT-MBE epifilm GaMnAs by standard e-beam lithography and wet-etch chemistries, as well as a ``break-junction method'' to further decrease constriction size. Four-point probe DC IV measurements- with applied fields at varying angles to wire axis- are utilized to study the transport mechanism- as well as magnetic properties. As constriction size approaches epifilm thickness, nonlinear IV response is observed with a differing field dependence on temperature. As constrictions become smaller, we observe a tunneling AMR-like behavior. This effect is more evident after series of high current pulses are applied to decrease the constriction width. ``Break-junction'' method results in higher constriction resistances and increases in resulting MR values.

Cho, Sung Un; Choi, Hyung Kook; Dasilva, Fabio C. S.; Osminer, Teresa; Pappas, David P.; Park, Yun Daniel

2009-03-01

357

Transport in time-dependent dynamical systems: Finite-time coherent sets  

E-print Network

a finite time duration. We are particularly interested in those regions that remain coherent and relatively skeletons of the time-dependent dynamics around which the chaotic dynamics occurs relatively independently an ordered skeleton often hidden in complicated flows. A recent comparison of the geometric and probabilistic

Froyland, Gary

358

Identification and functional analysis of a splice variant of mouse sodium-dependent phosphate transporter Npt2c.  

PubMed

Mutations in the SLC34A3 gene, a sodium-dependent inorganic phosphate (Pi) cotransporter, also referred to as NaPi IIc, causes hereditary hypophosphatemic rickets with hypercalciuria (HHRH), an autosomal recessive disorder. In human and rodent, NaPi IIc is mainly localized in the apical membrane of renal proximal tubular cells. In this study, we identified mouse NaPi IIc variant (Npt2c-v1) that lacks the part of the exon 3 sequence that includes the assumed translation initiation site of Npt2c. Microinjection of mouse Npt2c-v1 cRNA into Xenopus oocytes demonstrated that Npt2c-v1 showed sodium-dependent Pi cotransport activity. The characterization of pH dependency showed activation at extracellular alkaline-pH. Furthermore, Npt2c-v1 mediated Pi transport activity was significantly higher at any pH value than those of Npt2c. In an in vitro study, the localization of the Npt2c-v1 protein was detected in the apical membrane in opossum kidney cells. The expression of Npt2c-v1 mRNA was detected in the heart, spleen, testis, uterus, placenta, femur, cerebellum, hippocampus, diencephalon and brain stem of mouse. Using mouse bone primary cultured cells, we showed the expression of Npt2c-v1 mRNA. In addition, the Npt2c protein was detected in the spermatozoa head. Thus, Npt2c-v1 was expressed in extra-renal tissues such as epididymal spermatozoa and may function as a sodium-dependent phosphate transporter. PMID:22450000

Kuwahara, Shoji; Aranami, Fumito; Segawa, Hiroko; Onitsuka, Akemi; Honda, Naoko; Tominaga, Rieko; Hanabusa, Etsuyo; Kaneko, Ichiro; Yamanaka, Setsuko; Sasaki, Shohei; Ohi, Akiko; Nomura, Kengo; Tatsumi, Sawako; Kido, Shinsuke; Ito, Mikiko; Miyamoto, Ken-ichi

2012-01-01

359

Regulation of monocarboxylic acid transporter-1 by cAMP dependent vesicular trafficking in brain microvascular endothelial cells.  

PubMed

In this study, a detailed characterization of Monocarboxylic Acid Transporter-1 (Mct1) in cytoplasmic vesicles of cultured rat brain microvascular endothelial cells shows them to be a diverse population of endosomes intrinsic to the regulation of the transporter by a brief 25 to 30 minute exposure to the membrane permeant cAMP analog, 8Br-cAMP. The vesicles are heterogeneous in size, mobility, internal pH, and co-localize with discreet markers of particular types of endosomes including early endosomes, clathrin coated vesicles, caveolar vesicles, trans-golgi, and lysosomes. The vesicular localization of Mct1 was not dependent on its N or C termini, however, the size and pH of Mct1 vesicles was increased by deletion of either terminus demonstrating a role for the termini in vesicular trafficking of Mct1. Using a novel BCECF-AM based assay developed in this study, 8Br-cAMP was shown to decrease the pH of Mct1 vesicles after 25 minutes. This result and method were confirmed in experiments with a ratiometric pH-sensitive EGFP-mCherry dual tagged Mct1 construct. Overall, the results indicate that cAMP signaling reduces the functionality of Mct1 in cerebrovascular endothelial cells by facilitating its entry into a highly dynamic vesicular trafficking pathway that appears to lead to the transporter's trafficking to autophagosomes and lysosomes. PMID:24454947

Uhernik, Amy L; Li, Lun; LaVoy, Nathan; Velasquez, Micah J; Smith, Jeffrey P

2014-01-01

360

Proteasome Failure Promotes Positioning of Lysosomes around the Aggresome via Local Block of Microtubule-Dependent Transport  

PubMed Central

Ubiquitinated proteins aggregate upon proteasome failure, and the aggregates are transported to the aggresome. In aggresomes, protein aggregates are actively degraded by the autophagy-lysosome pathway, but why targeting the aggresome promotes degradation of aggregated species is currently unknown. Here we report that the important factor in this process is clustering of lysosomes around the aggresome via a novel mechanism. Proteasome inhibition causes formation of a zone around the centrosome where microtubular transport of lysosomes is suppressed, resulting in their entrapment and accumulation. Microtubule-dependent transport of other organelles, including autophagosomes, mitochondria, and endosomes, is also blocked in this entrapment zone (E-zone), while movement of organelles at the cell periphery remains unaffected. Following the whole-genome small interfering RNA (siRNA) screen for proteins involved in aggresome formation, we defined the pathway that regulates formation of the E-zone, including the Stk11 protein kinase, the Usp9x deubiquitinating enzyme, and their substrate kinase MARK4. Therefore, upon proteasome failure, targeting of aggregated proteins of the aggresome is coordinated with lysosome positioning around this body to facilitate degradation of the abnormal species. PMID:24469403

Zaarur, Nava; Meriin, Anatoli B.; Bejarano, Eloy; Xu, Xiaobin; Gabai, Vladimir L.; Cuervo, Ana Maria

2014-01-01

361

Lead inhibition of Mg/sup 2 +/-ATP-dependent calcium transport in rat liver plasma membranes  

SciTech Connect

In every tissue in which lead/calcium interactions have been examined, lead interferes with cellular calcium homeostasis resulting in an apparent increase in cellular calcium and alterations in calcium-mediated processes. The mechanism(s) by which lead increases cellular calcium are unknown. This study examines the effect of lead (5 nM to 50 ..mu..M) on Mg/sup 2 +/-ATP-dependent calcium transport activity in rat liver plasma membranes. Plasma membrane vesicles were prepared by Percoll density gradient centrifugation. This preparation shows a Mg/sup 2 +/-ATP-dependent calcium uptake with an initial rate of 5 nmol/mg protein/min and reaches a total equilibrium accumulation of 33 nmol/mg protein within 20 min at 20 ..mu..M CaCl/sub 2/, 1 mM ATP, 5 mM MgCl/sub 2/, 100 mM KCl, 5 mM azide, 30 mM histidine-imidazole, pH 6.8. Under these conditions lead inhibits calcium accumulation with half maximal inhibition at 1 ..mu..M; yet even at 50 nM lead, significant inhibition is observed. These observations indicate that lead impairs plasma membrane Ca/sup 2 +/ transport. As a result cellular calcium homeostatis is perturbed. This may represent an important mechanism in the expression of lead toxicity.

Schanne, F.A.X.

1986-03-01

362

Phosphoenolpyruvate-dependent phosphorylation of hexoses by ruminal bacteria: evidence for the phosphotransferase transport system.  

PubMed Central

Six species of ruminal bacteria were surveyed for the phosphoenolpyruvate (PEP)-dependent phosphorylation of glucose. Selenomonas ruminantium HD4, Streptococcus bovis JB1, and Megasphaera elsdenii B159 all showed significant activity, but Butyrivibrio fibrisolvens 49, Bacteroides succinogenes S85, and Bacteroides ruminicola B1(4) showed low rates of PEP-dependent phosphorylation and much higher rates in the presence of ATP. S. ruminantium HD4, S. bovis JB1, and M. elsdenii B159 also used PEP to phosphorylate the nonmetabolizable glucose analog 2-deoxy-D-glucose (2-DG). Rates of 2-DG phosphorylation with ATP were negligible for S. bovis JB1 and M. elsdenii B159, but toluene-treated cells of S. ruminantium HD4 phosphorylated 2-DG in the presence of ATP as well as PEP. Cell-free extracts of S. ruminantium HD4 used ATP but not PEP to phosphorylate glucose and 2-DG. Since PEP could serve as a phosphoryl donor in toluene-treated cells but not in cell-free extracts, there was evidence for membrane and hence phosphotransferase system involvement in the PEP-dependent activity. The ATP-dependent phosphorylating enzymes from S. ruminantium HD4 and S. bovis JB1 had molecular weights of approximately 48,000 and were not inhibited by glucose 6-phosphate. Based on these criteria, they were glucokinases rather than hexokinases. The S. ruminantium HD4 glucokinase was competitively inhibited by 2-DG and mannose, sugars that differ from glucose in the C-2 position. Since 2-DG was a competitive inhibitor of glucose, the same enzyme probably phosphorylates both sugars. The S. bovis JB1 glucokinase was not inhibited by either 2-DG or mannose and had a higher Km and Vmax for glucose. PMID:3789722

Martin, S A; Russell, J B

1986-01-01

363

Orientational imaging of single molecules by using azimuthal and radial polarizations.  

PubMed

Three-dimensional molecular orientations of single fluorescence molecules in polymeric thin films were measured by focused azimuthally and radially polarized light, in which we found that the fluorescence intensity was dependent on the depth position of the molecule with respect to the film surface. We found that the fluorescence intensity for a molecule which is 80 nm deep in the film excited by radial polarization is appreciably larger when compared with the fluorescence intensity for a molecule which is also excited by radial polarization but which is closer to the polymer/air interface, a feature which leads to different fluorescence intensities, under excitation by radial polarization, for molecules with the same polar orientation but with different depths inside the film. We also found that the variation of fluorescence intensity from a molecule inside an 80 nm film in radial polarization is appreciably larger compared with one in azimuthal polarization. These findings were confirmed by comparing experiments using different thickness films with theoretically calculated electric field distributions. PMID:20146536

Ishitobi, Hidekazu; Nakamura, Issei; Hayazawa, Norihiko; Sekkat, Zouheir; Kawata, Satoshi

2010-03-01

364

Azimuthal asymmetries for hadron distributions inside a jet in hadronic collisions  

SciTech Connect

Using a generalized parton model approach including spin and intrinsic parton motion effects, and assuming the validity of factorization for large-p{sub T} jet production in hadronic collisions, we study the azimuthal distribution around the jet axis of leading unpolarized or (pseudo)scalar hadrons, namely pions, produced in the jet fragmentation process. We identify the observable leading-twist azimuthal asymmetries for the unpolarized and single-polarized case related to quark and gluon-originated jets. We account for all physically allowed combinations of the transverse momentum-dependent (TMD) parton distribution and fragmentation functions, with special attention to the Sivers, Boer-Mulders, and transversity quark distributions, and to the Collins fragmentation function for quarks (and to the analogous functions for gluons). For each of these effects we evaluate, at central and forward rapidities and for kinematical configurations accessible at BNL-RHIC, the corresponding potentially maximized asymmetry (for {pi}{sup +} production), obtained by saturating natural positivity bounds (and the Soffer bound for transversity) for the distribution and fragmentation functions involved and summing additively all partonic contributions. We then estimate, for both neutral and charged pions, the asymmetries involving TMD functions for which parametrizations are available. We also study the role of the different mechanisms, and the corresponding transverse single-spin asymmetries, for large-p{sub T} inclusive-jet production.

D'Alesio, Umberto; Pisano, Cristian [Dipartimento di Fisica, Universita di Cagliari, Cittadella Universitaria, I-09042 Monserrato (Italy); Istituto Nazionale di Fisica Nucleare, Sezione di Cagliari, C. P. 170, I-09042 Monserrato (Italy); Murgia, Francesco [Istituto Nazionale di Fisica Nucleare, Sezione di Cagliari, C. P. 170, I-09042 Monserrato (Italy)

2011-02-01

365

Glutathione-Conjugate Transport by RLIP76 is required for Clathrin-Dependent Endocytosis and Chemical Carcinogenesis**  

PubMed Central

Targeted depletion of the RALBP1 encoded 76 kDa splice variant, RLIP76, causes marked and sustained regression of human xenografts of lung, colon, prostate, and kidney cancer without toxicity in nude mouse models. We proposed that the remarkable efficacy and broad-spectrum of RLIP76-targeted therapy is because its glutathione-conjugate (GS-E) transport-activity is required for clathrin-dependent endocytosis (CDE), that regulates all ligand-receptor signaling, and that RLIP76 is required not only for survival of cancer cells, but also for their very existence. We studied RLIP76 mutant proteins, and the functional consequences of their expression into RLIP76?/? MEFs, and identified key residues for GS-E binding in RLIP76, established the requirement of RLIP76-mediated GS-E transport for CDE, and demonstrated a direct correlation between GS-E transport activities with CDE. Depletion of RLIP76 nearly completely blocked signaling down-stream of EGF in a CDE-dependent manner, and Wnt5a signaling in a CDE-independent manner. The seminal prediction of this hypothesis, that RLIP76?/? mice will be deficient in chemical neoplasia, was confirmed. Benzo[a]pyrene, dimethylbenzanthracene and phorbol esters are ineffective in causing neoplasia in RLIP76?/?. PMA-induced skin carcinogenesis in RLIP76+/+ mouse was suppressed completely by depletion of either PKC? or RLIP76 by siRNA or antisense, and could be restored by topical application of RLIP76 protein in RLIP76?/? mouse skin. Likewise, chemical pulmonary carcinogenesis was absent in female and nearly absent in male RLIP76?/? mice. In RLIP76?/? mice, p53, p38, and JNK activation did not occur in response to either carcinogen. Our findings demonstrate a fundamental role of RLIP76 in chemical carcinogenesis. PMID:21220488

Singhal, Sharad S.; Wickramarachchi, Dilki; Yadav, Sushma; Singhal, Jyotsana; Leake, Kathryn; Vatsyayan, Rit; Chaudhary, Pankaj; Lelsani, Poorna; Suzuki, Sumihiro; Yang, Shaohua; Awasthi, Yogesh C.; Awasthi, Sanjay

2011-01-01

366

Protein Kinase C-dependent Ubiquitination and Clathrin-mediated Endocytosis of the Cationic Amino Acid Transporter CAT-1*  

PubMed Central

Cationic amino acid transporter 1 (CAT-1) is responsible for the bulk of the uptake of cationic amino acids in most mammalian cells. Activation of protein kinase C (PKC) leads to down-regulation of the cell surface CAT-1. To examine the mechanisms of PKC-induced down-regulation of CAT-1, a functional mutant of CAT-1 (CAT-1-HA-GFP) was generated in which a hemagglutinin antigen (HA) epitope tag was introduced into the second extracellular loop and GFP was attached to the carboxyl terminus. CAT-1-HA-GFP was stably expressed in porcine aorthic endothelial and human epithelial kidney (HEK) 293 cells. Using the HA antibody internalization assay we have demonstrated that PKC-dependent endocytosis was strongly inhibited by siRNA depletion of clathrin heavy chain, indicating that CAT-1-HA-GFP internalization requires clathrin-coated pits. Internalized CAT-1-HA-GFP was accumulated in early, recycling, and late endosomes. PKC activation also resulted in ubiquitination of CAT-1. CAT-1 ubiquitination and endocytosis in phorbol ester-stimulated porcine aorthic endothelial and HEK293 cells were inhibited by siRNA knockdown of NEDD4-2 and NEDD4-1 E3 ubiquitin ligases, respectively. In contrast, ubiquitination and endocytosis of the dopamine transporter was dependent on NEDD4-2 in all cell types tested. Altogether, our data suggest that ubiquitination mediated by NEDD4-2 or NEDD4-1 leading to clathrin-mediated endocytosis is the common mode of regulation of various transporter proteins by PKC. PMID:21212261

Vina-Vilaseca, Arnau; Bender-Sigel, Julia; Sorkina, Tatiana; Closs, Ellen Ildicho; Sorkin, Alexander

2011-01-01

367

Advances in colloid and biocolloid transport in porous media: particle size-dependent dispersivity and gravity effects  

NASA Astrophysics Data System (ADS)

Accurate prediction of colloid and biocolloid transport in porous media relies heavily on usage of suitable dispersion coefficients. The widespread procedure for dispersion coefficient determination consists of conducting conservative tracer experiments and subsequently fitting the collected breakthrough data with a selected advection-dispersion transport model. The fitted dispersion coefficient is assumed to characterize the porous medium and is often used thereafter to analyze experimental results obtained from the same porous medium with other solutes, colloids, and biocolloids. The classical advection-dispersion equation implies that Fick's first law of diffusion adequately describes the dispersion process, or that the dispersive flux is proportional to the concentration gradient. Therefore, the above-described procedure inherently assumes that the dispersive flux of all solutes, colloids and biocolloids under the same flow field conditions is exactly the same. Furthermore, the available mathematical models for colloid and biocoloid transport in porous media do not adequately account for gravity effects. Here an extensive laboratory study was undertaken in order to assess whether the dispersivity, which traditionally has been considered to be a property of the porous medium, is dependent on colloid particle size, interstitial velocity and length scale. The breakthrough curves were successfully simulated with a mathematical model describing colloid and biocolloid transport in homogeneous, water saturated porous media. The results demonstrated that the dispersivity increases very slowly with increasing interstitial velocity, and increases with column length. Furthermore, contrary to earlier results, which were based either on just a few experimental observations or experimental conditions leading to low mass recoveries, dispersivity was positively correlated with colloid particle size. Also, transport experiments were performed with biocolloids (bacteriophages: ?X174, MS2) and colloids (clays: kaolinite KGa-1b, montmorillonite STx-1b) in packed columns placed in various orientations (horizontal, vertical, and diagonal) under both up-flow and down-flow modes. All experiments were conducted under electrostatically unfavorable conditions. The experimental data were fitted with a newly developed, analytical, one dimensional, colloid and biocolloid transport model, accounting for gravity effects. The results revealed that flow direction has a significant influence on particle deposition. The rate of particle deposition was shown to be greater for up-flow than for down-flow direction, suggesting that gravity was a significant driving force for biocolloid and colloid deposition.

Chrysikopoulos, Constantinos V.; Manariotis, Ioannis D.; Syngouna, Vasiliki I.

2014-05-01

368

The Arabidopsis concentration-dependent influx/efflux transporter ABCB4 regulates cellular auxin levels in the root epidermis.  

PubMed

Arabidopsis ATP-binding cassette B4 (ABCB4) is a root-localised auxin efflux transporter with reported auxin uptake activity in low auxin concentrations. Results reported here demonstrate that ABCB4 is a substrate-activated regulator of cellular auxin levels. The contribution of ABCB4 to shootward auxin movement at the root apex increases with auxin concentration, but in root hair elongation assays ABCB4-mediated uptake is evident at low concentrations as well. Uptake kinetics of ABCB4 heterologously expressed in Schizosaccharomyces pombe differed from the saturation kinetics of AUX1 as uptake converted to efflux at threshold indole-3-acetic acid (IAA) concentrations. The concentration dependence of ABCB4 appears to be a direct effect on transporter activity, as ABCB4 expression and ABCB4 plasma membrane (PM) localisation at the root apex are relatively insensitive to changes in auxin concentration. However, PM localization of ABCB4 decreases with 1-naphthylphthalamic acid (NPA) treatment. Unlike other plant ABCBs studied to date, and consistent with decreased detergent solubility, ABCB4(pro) :ABCB4-GFP is partially internalised in all cell types by 0.05% DMSO, but not 0.1% ethanol. In trichoblasts, ABCB4(pro) :ABCB4-GFP PM signals are reduced by >200 nm IAA and 2,4-dichlorophenoxyacetic acid (2,4-D). In heterologous systems and in planta, ABCB4 transports benzoic acid with weak affinity, but not the oxidative catabolism products 2-oxindole-3-acetic-acid and 2-oxindole-3-acetyl-?-D-glucose. ABCB4 mediates uptake, but not efflux, of the synthetic auxin 2,4-D in cells lacking AUX1 activity. Results presented here suggest that 2,4-D is a non-competitive inhibitor of IAA transport by ABCB4 and indicate that ABCB4 is a target of 2,4-D herbicidal activity. PMID:21992190

Kubeš, Martin; Yang, Haibing; Richter, Gregory L; Cheng, Yan; M?odzi?ska, Ewa; Wang, Xia; Blakeslee, Joshua J; Carraro, Nicola; Petrášek, Jan; Zažímalová, Eva; Hoyerová, Klára; Peer, Wendy Ann; Murphy, Angus S

2012-02-01

369

The Distribution of the Elements in the Galactic Disk. II. Azimuthal and Radial Variation in Abundances from Cepheids  

NASA Astrophysics Data System (ADS)

This paper reports on the spectroscopic investigation of 101 Cepheids in the Carina region. These Cepheids extend previous samples by about 35% in number and increase the amount of the Galactic disk coverage especially in the direction of l ? 270°. The new Cepheids do not add much information to the radial gradient, but provide a substantial increase in azimuthal coverage. We find no azimuthal dependence in abundance over an 80° angle from the Galactic center in an annulus of 1 kpc depth centered on the Sun. A simple linear fit to the Cepheid data yields a gradient d[Fe/H]/dRG = -0.055 ± 0.003 dex kpc-1 which is somewhat shallower than found from our previous, smaller Cepheid sample.

Luck, R. E.; Andrievsky, S. M.; Kovtyukh, V. V.; Gieren, W.; Graczyk, D.

2011-08-01

370

Systematic Parameter Estimation of a Density-Dependent Groundwater-Flow and Solute-Transport Model  

NASA Astrophysics Data System (ADS)

A SEAWAT-based, flow and transport model of seawater-intrusion was developed for the Santa Barbara groundwater basin in southern California that utilizes dual-domain porosity. Model calibration can be difficult when simulating flow and transport in large-scale hydrologic systems with extensive heterogeneity. To facilitate calibration, the hydrogeologic properties in this model are based on the fraction of coarse and fine-grained sediment interpolated from drillers' logs. This approach prevents over-parameterization by assigning one set of parameters to coarse material and another set to fine material. Estimated parameters include boundary conditions (such as areal recharge and surface-water seepage), hydraulic conductivities, dispersivities, and mass-transfer rate. As a result, the model has 44 parameters that were estimated by using the parameter-estimation software PEST, which uses the Gauss-Marquardt-Levenberg algorithm, along with various features such as singular value decomposition to improve calibration efficiency. The model is calibrated by using 36 years of observed water-level and chloride-concentration measurements, as well as first-order changes in head and concentration. Prior information on hydraulic properties is also provided to PEST as additional observations. The calibration objective is to minimize the squared sum of weighted residuals. In addition, observation sensitivities are investigated to effectively calibrate the model. An iterative parameter-estimation procedure is used to dynamically calibrate steady state and transient simulation models. The resulting head and concentration states from the steady-state-model provide the initial conditions for the transient model. The transient calibration provides updated parameter values for the next steady-state simulation. This process repeats until a reasonable fit is obtained. Preliminary results from the systematic calibration process indicate that tuning PEST by using a set of synthesized observations generated from model output reduces execution times significantly. Parameter sensitivity analyses indicate that both simulated heads and chloride concentrations are sensitive to the ocean boundary conductance parameter. Conversely, simulated heads are sensitive to some parameters, such as specific fault conductances, but chloride concentrations are insensitive to the same parameters. Heads are specifically found to be insensitive to mobile domain texture but sensitive to hydraulic conductivity and specific storage. The chloride concentrations are insensitive to some hydraulic conductivity and fault parameters but sensitive to mass transfer rate and longitudinal dispersivity. Future work includes investigating the effects of parameter and texture characterization uncertainties on seawater intrusion simulations.

Stanko, Z.; Nishikawa, T.; Traum, J. A.

2013-12-01

371

Temperature-dependence of ink transport during thermal dip-pen nanolithography  

NASA Astrophysics Data System (ADS)

We investigate the control of tip temperature on feature size during dip-pen nanolithography (DPN) of mercaptohexadecanoic acid (MHA) on Au. Heated atomic force microscopy (AFM) probes operated between 25 °C and 50 °C wrote nanostructures of MHA for various dwell times and tip speeds. The feature size exhibited an exponential dependence on tip temperature with an apparent activation barrier of 165 kJ/mol. Analysis of the ink transfer process shows that, while ˜1/3 of the barrier is from ink dissolution into the meniscus, the rest reflects the barrier to adsorption onto the growing feature, a process that has been ignored in previous DPN models.

Chung, Sungwook; Felts, Jonathan R.; Wang, Debin; King, William P.; De Yoreo, James J.

2011-11-01

372

WILLI – a scintillator detector setup for studies of the zenith and azimuth variation of charge ratio and flux of atmospheric muons  

Microsoft Academic Search

The primary and secondary components of the cosmic radiation are influenced by the geomagnetic field. This leads - in addition to the variation with the zenith angle - to an azimuth dependence, in particular of the ratio of positive and negative muons, pronounced as East-West effect of muon charge ratio for low energy muons. The compact scintillator detector arrangement, WILLI,

I. M. Brancus; H. Rebel; A. Haungs; B. Mitrica; A. Bercuci; A. Saftoiu; M. Petcu; J. Wentz; O. Sima; G. Toma; M. Duma; C. Aiftimiei

2008-01-01

373

Lysine 27 Ubiquitination of the Mitochondrial Transport Protein Miro Is Dependent on Serine 65 of the Parkin Ubiquitin Ligase*  

PubMed Central

Mitochondrial transport plays an important role in matching mitochondrial distribution to localized energy production and calcium buffering requirements. Here, we demonstrate that Miro1, an outer mitochondrial membrane (OMM) protein crucial for the regulation of mitochondrial trafficking and distribution, is a substrate of the PINK1/Parkin mitochondrial quality control system in human dopaminergic neuroblastoma cells. Moreover, Miro1 turnover on damaged mitochondria is altered in Parkinson disease (PD) patient-derived fibroblasts containing a pathogenic mutation in the PARK2 gene (encoding Parkin). By analyzing the kinetics of Miro1 ubiquitination, we further demonstrate that mitochondrial damage triggers rapid (within minutes) and persistent Lys-27-type ubiquitination of Miro1 on the OMM, dependent on PINK1 and Parkin. Proteasomal degradation of Miro1 is then seen on a slower time scale, within 2–3 h of the onset of ubiquitination. We find Miro ubiquitination in dopaminergic neuroblastoma cells is independent of Miro1 phosphorylation at Ser-156 but is dependent on the recently identified Ser-65 residue within Parkin that is phosphorylated by PINK1. Interestingly, we find that Miro1 can stabilize phospho-mutant versions of Parkin on the OMM, suggesting that Miro is also part of a Parkin receptor complex. Moreover, we demonstrate that Ser-65 in Parkin is critical for regulating Miro levels upon mitochondrial damage in rodent cortical neurons. Our results provide new insights into the ubiquitination-dependent regulation of the Miro-mediated mitochondrial transport machinery by PINK1/Parkin and also suggest that disruption of this regulation may be implicated in Parkinson disease pathogenesis. PMID:24671417

Birsa, Nicol; Norkett, Rosalind; Wauer, Tobias; Mevissen, Tycho E. T.; Wu, Hsiu-Chuan; Foltynie, Thomas; Bhatia, Kailash; Hirst, Warren D.; Komander, David; Plun-Favreau, Helene; Kittler, Josef T.

2014-01-01

374

Stacking-dependent band gap and quantum transport in trilayer graphene  

NASA Astrophysics Data System (ADS)

Graphene is an extraordinary two-dimensional (2D) system with chiral charge carriers and fascinating electronic, mechanical and thermal properties. In multilayer graphene, stacking order provides an important yet rarely explored degree of freedom for tuning its electronic properties. For instance, Bernal-stacked trilayer graphene (B-TLG) is semi-metallic with a tunable band overlap, and rhombohedral-stacked trilayer graphene (r-TLG) is predicted to be semiconducting with a tunable band gap. These multilayer graphenes are also expected to exhibit rich novel phenomena at low charge densities owing to enhanced electronic interactions and competing symmetries. Here we demonstrate the dramatically different transport properties in TLG with different stacking orders, and the unexpected spontaneous gap opening in charge neutral r-TLG. At the Dirac point, B-TLG remains metallic, whereas r-TLG becomes insulating with an intrinsic interaction-driven gap ~6meV. In magnetic fields, well-developed quantum Hall (QH) plateaux in r-TLG split into three branches at higher fields. Such splitting is a signature of the Lifshitz transition, a topological change in the Fermi surface, that is found only in r-TLG. Our results underscore the rich interaction-induced phenomena in trilayer graphene with different stacking orders, and its potential towards electronic applications.

Bao, W.; Jing, L.; Velasco, J.; Lee, Y.; Liu, G.; Tran, D.; Standley, B.; Aykol, M.; Cronin, S. B.; Smirnov, D.; Koshino, M.; McCann, E.; Bockrath, M.; Lau, C. N.

2011-12-01

375

Gene-dose dependent effects of methamphetamine on interval timing in dopamine-transporter knockout mice.  

PubMed

The dopamine transporter (DAT) is the major regulator of the spatial and temporal resolution of dopaminergic neurotransmission in the brain. Hyperdopaminergic mice with DAT gene deletions were evaluated for their ability to perform duration discriminations in the seconds-to-minutes range. DAT -/- mice were unable to demonstrate temporal control of behavior in either fixed-interval or peak-interval timing procedures, whereas DAT +/- mice were similar to DAT +/+ mice under normal conditions. Low to moderate-dose methamphetamine (MAP) challenges indicated that DAT +/- mice were less sensitive to the clock-speed enhancing effects of MAP compared with DAT +/+ mice. In contrast, DAT +/- mice were more vulnerable than DAT +/+ mice to the disruptive effects of MAP at high doses as revealed by the elevation of response rate in the right hand tail of the Gaussian-shaped timing functions. Moreover, this treatment made DAT +/- mice functionally equivalent to DAT -/- mice in terms of the loss of temporal control. Taken together, these results demonstrate the importance of dopaminergic control of interval timing in cortico-striatal circuits and the potential link of timing dysfunctions to schizophrenia and drug abuse. PMID:21296093

Meck, Warren H; Cheng, Ruey-Kuang; MacDonald, Christopher J; Gainetdinov, Raul R; Caron, Marc G; Cevik, Münire Özlem

2012-03-01

376

Study of thickness-dependent magnetic and transport properties of Fe/Al nanostructures  

NASA Astrophysics Data System (ADS)

The paper presents magnetic and transport properties of compositionally modulated Fe/Al multilayer structures (MLS), with an overall atomic concentration ratio of Fe:Al = 3:1, 2:1 and 1:1. All MLS show soft ferromagnetic behaviour at room temperature (RT) with an in-plane easy axis of magnetization. In each case, coercivity increases continuously and magnetization decreases with an increase in temperature due to enhancement in the anisotropy as a result of non-uniform and disordered formation of thin intermixed (dead) FeAl layer at the interfaces. The Curie temperature obtained for the MLS is much less than that of bcc Fe but is well above RT. The observed magnetic behaviour is mainly attributed to the formation of different FeAl phases and increase in anti-ferromagnetic interlayer coupling with addition of Al. The formation of these phases is also supported by resistivity results. The results of this research enabled us to understand that by controlling of layers thickness and temperature in multilayer systems, the nanogranular thin films with good resistive and soft magnetic properties can be obtained.

Vyas, Anupam; Rajan, Sandeep; Kumar, Anil; Brajpuriya, Ranjeet

2014-09-01

377

Influence of model melanoidins on calcium-dependent transport mechanisms in smooth muscle tissue.  

PubMed

Melanoidins obtained from L-arginine and D-glucose (MW > 3500 Da) were tested for their ability to influence the contractility of gastric smooth muscles. A study within the range 0.1-10 mg/mL revealed that at low concentrations, the melanoidins provoked concentration-dependent contraction, whereas a muscle relaxation was registered at high concentrations. The contraction was preceded by changes in the calcium membrane current as measured by single sucrose-gap method and significantly attenuated by the calcium channel blockers D-600 and nifedipine. Measurements with Ca(2+)-selective electrode showed that the melanoidins decreased the concentration of ionized Ca(2+ )in tissue bath in concentration-dependent manner. Experiments carried out in solutions with lower than normal Ca(2+) concentration and using melanoidins preliminary saturated with Ca(2+ )confirmed that the calcium chelation by melanoidins was a key contributing cause for the development of relaxant response. The results obtained showed that the melanoidins could influence the contractility of smooth muscles through at least two pathways: at low concentrations they caused depolarization and activation of L-type calcium channels, stimulated the Ca(2+ )influx, and provoked contraction, whereas at high concentrations calcium binding by melanoidins led to significant depletion of extracellular calcium ions and contributed to the relaxation process observed. PMID:17357983

Stefanova, Iliyana D; Argirova, Mariana D; Krustev, Athanas D

2007-04-01

378

Improved formation evaluation using azimuthal porosity data while drilling  

SciTech Connect

Measurement of formation porosity and lithology in azimuthal quadrants around the borehole is now available. This new information is provided by a nuclear tool that makes azimuthal density, photoelectric factor and neutron porosity measurements while drilling. In addition. an ultrasonic sensor provides a tool standoff measurement in each quadrant. While rotating the quadrants are defined by a magnetometer and oriented with the gravity vector, so that bottom, left, right and top quadrants are identified. The tool can be run with several different stabilizer sizes or without a stabilizer, giving the driller more latitude in configuring the bottomhole assembly. The azimuthal capability allows the measurement of porosity with an unstabilized or {open_quotes}slick{close_quotes} tool without degradation of the measurement. This is accomplished by computing the porosity from the bottom quadrant where there is little tool standoff in deviated or horizontal wells. Utilizing bottom quadrant porosities also results in improved measurement accuracy in cases where borehole conditions are poor due to enlargement or washouts. When the tool is stabilized, the quadrant porosity and lithology measurements result in improved geosteering as well as providing a quantitative measure of formation heterogeneity. At bed boundaries, comparison of top and bottom logs in real time results in better bed boundary detection and confirmation of the tool location within the pay zone. When the tool is between boundaries, an heterogeneity indicator can be computed from the quadrant density, lithology and neutron porosity logs to better evaluate complex formations. The measurement of tool standoff per quadrant provides information on borehole size, shape and rugosity. The data can be used to indicate borehole stability on subsequent bit trips. The paper describes the method of the measurement, hardware implementation and log examples illustrating the tool features.

Evans, M.; Best, D.; Holenka, J. [and others

1995-12-31

379

Microtubule-dependent transport of vimentin filament precursors is regulated by actin and by the concerted action of Rho- and p21-activated kinases.  

PubMed

Intermediate filaments (IFs) form a dense and dynamic network that is functionally associated with microtubules and actin filaments. We used the GFP-tagged vimentin mutant Y117L to study vimentin-cytoskeletal interactions and transport of vimentin filament precursors. This mutant preserves vimentin interaction with other components of the cytoskeleton, but its assembly is blocked at the unit-length filament (ULF) stage. ULFs are easy to track, and they allow a reliable and quantifiable analysis of movement. Our results show that in cultured human vimentin-negative SW13 cells, 2% of vimentin-ULFs move along microtubules bidirectionally, while the majority are stationary and tightly associated with actin filaments. Rapid motor-dependent transport of ULFs along microtubules is enhanced ? 5-fold by depolymerization of actin cytoskeleton with latrunculin B. The microtubule-dependent transport of vimentin ULFs is further regulated by Rho-kinase (ROCK) and p21-activated kinase (PAK): ROCK inhibits ULF transport, while PAK stimulates it. Both kinases act on microtubule transport independently of their effects on actin cytoskeleton. Our study demonstrates the importance of the actin cytoskeleton to restrict IF transport and reveals a new role for PAK and ROCK in the regulation of IF precursor transport.-Robert, A., Herrmann, H., Davidson, M. W., and Gelfand, V. I. Microtubule-dependent transport of vimentin filament precursors is regulated by actin and by the concerted action of Rho- and p21-activated kinases. PMID:24652946

Robert, Amélie; Herrmann, Harald; Davidson, Michael W; Gelfand, Vladimir I

2014-07-01

380

What is the azimuthal quantum force in superconductor  

E-print Network

J.E. Hirsch notes in the recent paper arXiv: 0908.409 that the azimuthal quantum force, introduced ten years ago, would violate the principle of angular momentum conservation. It is specified in the present work that the essence and the method of logical deduction of the quantum force do not overstep the limits of the universally recognised quantum formalism. The puzzle revealed by J.E. Hirsch concerns rather of quantum mechanics in whole than a certain theory or work. The essence of this and other puzzles generated with quantum mechanics is considered shortly.

A. V. Nikulov

2011-04-26