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1

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

2

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

3

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

E-print Network

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

Hui Wang; for the STAR Collaboration

2012-01-01

4

Azimuthal ambipolar potential variations and tandem mirror transport  

Microsoft Academic Search

Azimuthal ambipolar potential variations are induced by the magnetic drifts in a quadrupole tandem mirror. Consequently, radial E x B drifts occur and contribute along with the magnetic drifts to the total radial flux in a collisional plasma. This effect is studied self-consistently in the resonant-plateau regime assuming Maxwell-Boltzmann electrons along the field lines. A general form exhibiting the contribution

X. S. Lee; J. R. Myra; P. J. Catto

1983-01-01

5

Azimuthal ambipolar potential variations and tandem mirror transport  

Microsoft Academic Search

Azimuthal ambipolar potential variations are induced by the magnetic drifts in a quadrupole tandem mirror. Consequently, radial E x B drifts occur and contribute along with the magnetic drifts to the total radial flux in a collisional plasma. This effect is studied self-consistently in the resonant-plateau regime assuming Maxwell--Boltzmann electrons along the field lines. A general form exhibiting the contribution

X. S. Lee; J. R. Myra; P. J. Catto

1984-01-01

6

Azimuthal ambipolar potential variations and tandem mirror transport  

Microsoft Academic Search

Azimuthal ambipolar potential variations are induced by the magnetic drifts in a qlodrupole tandem mirror. Consequently, radial E×B drifts occur and contribute along with the magnetic drifts to the total radial flux in a collisional plasma. This effect is studied self-consistently in the resonant-plateau regime assuming Maxwell–Boltzmann electrons along the field lines. A general form exhibiting the contribution of the

X. S. Lee; J. R. Myra; P. J. Catto

1984-01-01

7

Flavor dependent azimuthal asymmetries in unpolarized semi-inclusive DIS at HERMES  

NASA Astrophysics Data System (ADS)

The azimuthal cos? h and cos2? h modulations of the distribution of hadrons produced in unpolarized semi-inclusive deep-inelastic scattering of electrons and positrons off hydrogen and deuterium targets have been measured in the hermes experiment. For the first time these modulations were determined in a 4-Dimensional kinematic space for positively and negatively charged pions and kaons separately, as well as for unidentified hadrons. These azimuthal dependences are sensitive to the transverse motion and polarization of the quarks within the nucleon via, e.g., the Cahn, Boer-Mulders and Collins effects.

Giordano, F.

2014-01-01

8

Relationship between the azimuthal dependencies of nuclear modification factor and ridge yield  

SciTech Connect

The azimuthal angular dependence of the nuclear modification factor R{sub AA}(p{sub T},phi,N{sub part}) recently obtained by PHENIX is related at low p{sub T} to the trigger phi dependence of the ridge yield as measured by STAR in a framework in which the azimuthal anisotropy is driven by semihard scattering near the surface. Careful consideration of the initial geometry leads to the determination of a surface segment in which the production of semihard partons are responsible for the phi dependence of the inclusive distribution on the one hand and for the angular correlation in ridge phenomenology on the other. With v{sub 2} also being well reproduced along with R{sub AA} and ridge yield, all relevant phi dependencies in heavy-ion collisions can now be understood in a unified description that emphasizes the ridge production whether or not a trigger is used.

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

2010-03-15

9

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

10

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

11

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

E-print Network

We study the azimuthal angular dependence of back-to-back di-jet production in unpolarized hadron scattering $H_A+H_B \\to J_1 + J_2 +X$, 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 di-jet is of two identical quarks ($J_q+J_q$) or a quark-antiquark pair ($J_q+J_{\\bar{q}}$), there is a $\\cos \\delta \\phi$ angular dependence of the di-jet, with $\\delta \\phi=\\phi_1-\\phi_2$, and $\\phi_1$ and $\\phi_2$ are the azimuthal angles of the two individual jets. In the case of $J_q+J_q$ 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 di-jet production at RHIC, showing that the color factor enhancement in the angular dependent of $J_q+J_q$ production will reverse the sign of the asymmetry.

Zhun Lu; Ivan Schmidt

2008-05-26

12

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

SciTech Connect

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

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

2011-09-15

13

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

NASA Astrophysics Data System (ADS)

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

Ismail, M.; Adel, A.

2011-09-01

14

The Tricky Azimuthal Dependence of Jet Quenching at RHIC and LHC via CUJET2.0  

E-print Network

High transverse momentum neutral pion and charged hadron suppression pattern with respect to reaction plane at RHIC and LHC energies in central and semi-peripheral AA collisions are studied in a perturbative QCD based model, CUJET2.0. CUJET2.0 has dynamical DGLV radiation kernel and Thoma-Gyulassy elastic energy loss, with both being generalized to including multi-scale running strong coupling as well as energy loss probability fluctuations, and the full jet path integration is performed in a low $p_T$ flow data constrained medium which has 2+1D viscous hydrodynamical expanding profile. We find that in CUJET2.0, with only one control parameter, $\\alpha_{max}$, the maximum coupling strength, fixed to be 0.26, the computed nuclear modification factor $R_{AA}$ in central and semi-peripheral AA collisions are consistent with RHIC and LHC data at average $\\chi^2/d.o.f.<1.5$ level. Simultaneous agreements with high $p_T$ azimuthal anisotropy $v_2$ data are acquired given average $\\alpha_{max}$ over in-plane and out-of-plane paths varying as less as 10\\%, suggests a non-trivial dependence of the high $p_T$ single particle $v_2$ on the azimuthally varied strong coupling.

Jiechen Xu; Alessandro Buzzatti; Miklos Gyulassy

2014-07-20

15

Anisotropic parton escape is the dominant source of azimuthal anisotropy from A Multi-Phase Transport  

E-print Network

We trace the development of azimuthal anisotropy ($v_n$) in A Multi-Phase Transport (AMPT) model using parton-parton collision history. The parton $v_n$ is studied as a function of the number of collisions of each parton in Au+Au and d+Au collisions at $\\sqrt{S_{NN}}$=200~GeV. It is found that the majority of $v_n$ comes from the anisotropic escape probability of partons, with no fundamental difference at low and high transverse momenta. The contribution to $v_n$ from the parton collective flow appears small; however, it is this small anisotropy from the collective flow, not that from the anisotropic escape probability, that is most relevant for medium properties in heavy ion collisions.

He, Liang; Lin, Zi-Wei; Liu, Feng; Molnar, Denes; Wang, Fuqiang

2015-01-01

16

Azimuthal anisotropies of reconstructed jets in Pb + Pb collisions at ?sNN =2.76 TeV in a multiphase transport model  

NASA Astrophysics Data System (ADS)

Azimuthal anisotropies of reconstructed jets [vnjet(n=2,3)] have been investigated in Pb + Pb collisions at the center of mass energy ?sNN =2.76 TeV within a framework of a multiphase transport (AMPT) model. The v2jet is in good agreement with the recent ATLAS data. However, the v3jet shows a smaller magnitude than v2jet, and approaches zero at a larger transverse momentum. It is attributed to the path-length dependence in which the jet energy loss fraction depends on the azimuthal angles with respect to different orders of event planes. The ratio vnjet/?n increases from peripheral to noncentral collisions, and vnjet increases with the initial spatial asymmetry (?n) for a given centrality bin. These behaviors indicate that the vnjet is produced by the strong interactions between jet and the partonic medium with different initial geometry shapes. Therefore, azimuthal anisotropies of reconstructed jet are proposed as a good probe to study the initial spatial fluctuations, which are expected to provide constraints on the path-length dependence of jet quenching models.

Nie, Mao-Wu; Ma, Guo-Liang

2014-07-01

17

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

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

18

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

19

Dependence of enhanced asymmetry-induced transport on collision frequency  

SciTech Connect

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

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

2014-07-15

20

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

21

Azimuthal Offset-Dependent Attributes (AVO And FVO) Applied To Fracture Detection  

E-print Network

Using the amplitude versus offset (AVO) and the frequency versus offset (FVO) information, the diagnostic ability of P-wave seismic data in fracture detection is investigated. The offset-dependent attributes (AVO and FVO) ...

Shen, Feng

1999-01-01

22

Polar-azimuthal angle dependent efficiency of different infrared superconducting nanowire single-photon detector designs  

E-print Network

The illumination-angle-dependent absorptance was determined for three types of superconducting-nanowire singlephoton detector (SNSPD) designs: 1. periodic bare niobium-nitride (NbN) stripes with dimensions of conventional ...

Csete, Maria

23

Rapidity dependence of azimuthal correlations for p+p and d+Au at ?s = 200GeV  

NASA Astrophysics Data System (ADS)

Forward di-jet production in d+Au collisions at RHIC provides sensitivity to Bjorken-x between 0.001 and 0.02 for the nuclear gluon density. The STAR experiment at RHIC has continuous azimuthal coverage with electromagnetic calorimeters for pseudo-rapidity from-1 to 4. We have measured forward+mid-rapidity ?0 - ?0 and ?0 - h azimuthal correlations and forward+forward rapidity ?0 - ?0 azimuthal correlations. Both analyses use the Forward Meson Spectrometer (FMS) triggered data in RHIC 2008 run p+p and d+Au collisions at = 200 GeV. The end-cap electromagnetic calorimeter (EEMC) at STAR covers pseudo-rapidity from 1.07 to 2. This provides us sensitivity to the nuclear gluon density at intermediate x values. Preliminary results on the ?0 - ?0 and ?0 + jet-like azimuthal correlations with both the FMS and the EEMC will be discussed.

Li, Xuan; STAR Collaboration

2011-09-01

24

Particle-Type Dependence of Azimuthal Anisotropy and Nuclear Modification of Particle Production in Au+Au Collisions at &surd;(sNN)=200 GeV  

Microsoft Academic Search

We present STAR measurements of the azimuthal anisotropy parameter v2 and the binary-collision scaled centrality ratio RCP for kaons and lambdas (Lambda+Lambda¯) at midrapidity in Au+Au collisions at &surd;(sNN)=200 GeV. In combination, the v2 and RCP particle-type dependencies contradict expectations from partonic energy loss followed by standard fragmentation in vacuum. We establish pT≈5 GeV\\/c as the value where the centrality

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; H. Bichsel; 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. Calderón de La Barca Sánchez; 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; M. Estienne; 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; L. Gaudichet; M. Germain; F. Geurts; V. Ghazikhanian; P. Ghosh; J. E. Gonzalez; O. Grachov; V. Grigoriev; S. Gronstal; D. Grosnick; M. Guedon; S. M. Guertin; A. Gupta; E. Gushin; T. D. Gutierrez; 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; H. Jiang; I. Johnson; P. G. Jones; E. G. Judd; S. Kabana; M. Kaneta; M. Kaplan; D. Keane; V. Yu. Khodyrev; J. Kiryluk; A. Kisiel; J. Klay; S. R. Klein; A. Klyachko; D. D. Koetke; T. Kollegger; M. Kopytine; L. Kotchenda; A. D. Kovalenko; M. Kramer; P. Kravtsov; V. I. Kravtsov; K. Krueger; C. Kuhn; A. I. Kulikov; A. Kumar; G. J. Kunde; C. L. Kunz; R. Kh. Kutuev; A. A. Kuznetsov; M. A. Lamont; J. M. Landgraf; S. Lange; C. P. Lansdell; B. Lasiuk; F. Laue; J. Lauret; A. Lebedev; R. Lednický; M. J. Levine; C. Li; Q. Li; S. J. Lindenbaum; M. A. Lisa; F. Liu; L. Liu; Z. Liu; Q. J. Liu; T. Ljubicic; W. J. Llope; H. Long; R. S. Longacre; M. Lopez-Noriega; W. A. Love; T. Ludlam; D. Lynn; J. Ma; Y. G. Ma; D. Magestro; S. Mahajan; L. K. Mangotra; D. P. Mahapatra; R. Majka; R. Manweiler; S. Margetis; C. Markert; L. Martin; J. Marx; H. S. Matis; Yu. A. Matulenko; T. S. McShane; F. Meissner; Yu. Melnick; A. Meschanin; M. Messer; M. L. Miller; Z. Milosevich; N. G. Minaev; C. Mironov; D. Mishra; J. Mitchell; B. Mohanty; L. Molnar; C. F. Moore; M. J. Mora-Corral; D. A. Morozov; V. Morozov; M. M. de Moura; M. G. Munhoz; B. K. Nandi; S. K. Nayak; T. K. Nayak; J. M. Nelson; P. Nevski; V. A. Nikitin; L. V. Nogach; B. Norman; S. B. Nurushev; G. Odyniec; A. Ogawa; V. Okorokov; M. Oldenburg; D. Olson; G. Paic; S. U. Pandey; S. K. Pal; Y. Panebratsev; S. Y. Panitkin; A. I. Pavlinov; T. Pawlak; V. Perevoztchikov; C. Perkins; W. Peryt; V. A. Petrov; S. C. Phatak; R. Picha; M. Planinic; J. Pluta; N. Porile; J. Porter; A. M. Poskanzer; M. Potekhin; E. Potrebenikova; B. V. Potukuchi; D. Prindle; C. Pruneau; J. Putschke; G. Rai; G. Rakness; R. Raniwala; S. Raniwala; O. Ravel; R. L. Ray; S. V. Razin; D. Reichhold; J. G. Reid; G. Renault; F. Retiere; A. Ridiger; H. G. Ritter; J. B. Roberts; O. V. Rogachevski; J. L. Romero; A. Rose; C. Roy; L. J. Ruan; R. Sahoo; I. Sakrejda; S. Salur; J. Sandweiss; I. Savin; J. Schambach; R. P. Scharenberg; N. Schmitz; L. S. Schroeder; K. Schweda; J. Seger; D. Seliverstov; P. Seyboth; E. Shahaliev; M. Shao; M. Sharma; K. E. Shestermanov; S. S. Shimanskii; R. N. Singaraju; F. Simon; G. Skoro; N. Smirnov; R. Snellings; G. Sood; P. Sorensen; J. Sowinski; H. M. Spinka; B. Srivastava; S. Stanislaus; R. Stock; A. Stolpovsky; M. Strikhanov; B. Stringfellow; C. Struck; A. A. Suaide; E. Sugarbaker; C. Suire; M. Sumbera; B. Surrow; T. J. Symons; A. Szanto de Toledo; P. Szarwas; A. Tai; J. Takahashi; A. H. Tang; D. Thein; J. H. Thomas; V. Tikhomirov; M. Tokarev; M. B. Tonjes; T. A. Trainor; S. Trentalange; R. E. Tribble; M. D. Trivedi; V. Trofimov; O. Tsai; T. Ullrich; D. G. Underwood; G. van Buren; A. M. Vandermolen; A. N. Vasiliev; M. Vasiliev; S. E. Vigdor; Y. P. Viyogi; S. A. Voloshin; W. Waggoner; F. Wang; G. Wang; X. L. Wang; Z. M. Wang; H. Ward; J. W. Watson; R. Wells; G. D. Westfall; C. Whitten; H. Wieman; R. Willson; S. W. Wissink; R. Witt; J. Wood; J. Wu; N. Xu; Z. Xu; E. Yamamoto; P. Yepes; V. I. Yurevich; Y. V. Zanevski; I. Zborovský; H. Zhang; W. M. Zhang; Z. P. Zhang; P. A. Zolnierczuk; R. Zoulkarneev; J. Zoulkarneeva; A. N. Zubarev

2004-01-01

25

Nuclear suppression of azimuthal asymmetries in semi-inclusive deep inelastic scattering off polarized targets  

E-print Network

We extend the study of nuclear dependence of the transverse momentum dependent parton distribution functions and azimuthal asymmetries to semi-inclusive deep inelastic scattering (SIDIS) off polarized nuclear targets. We show that azimuthal asymmetries are suppressed for SIDIS off a polarized nuclear target relative to that off a polarized nucleon due to multiple scattering inside the nucleus. Using the value of transport parameter inside large nuclei extracted from jet quenching analyses in SIDIS off nuclear targets, we also present a numerical estimate of the nuclear suppression of the azimuthal asymmetry that might be useful to guide the future experimental studies of SIDIS off polarized nuclear targets.

Yu-kun Song; Zuo-tang Liang; Xin-Nian Wang

2014-02-13

26

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.

27

Azimuthal anisotropy of direct photons  

SciTech Connect

The electromagnetic bremsstrahlung produced by a quark interacting with nucleons or nuclei is azimuthally asymmetric. In the light-cone dipole approach this effect is related to the orientation dependent dipole cross section. Such a radiation anisotropy is expected to contribute to the azimuthal asymmetry of direct photons in pA and AA collisions, as well as in deep-inelastic scattering and in the production of dileptons.

Kopeliovich, B. Z. [Departamento de Fisica y Centro de Estudios Subatomicos, Universidad Tecnica Federico Santa Maria, Casilla 110-V, Valparaiso (Chile); Joint Institute for Nuclear Research, Dubna (Russian Federation); Pirner, H. J. [Institute for Theoretical Physics, University of Heidelberg, Philosophenweg 19, D-69120 Heidelberg (Germany); Rezaeian, A. H.; Schmidt, Ivan [Departamento de Fisica y Centro de Estudios Subatomicos, Universidad Tecnica Federico Santa Maria, Casilla 110-V, Valparaiso (Chile)

2008-02-01

28

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

29

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

SciTech Connect

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

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

2003-06-18

30

Measurement of the combined rapidity and pT dependence of dijet azimuthal decorrelations in ppbar collisions at ?{s}=1.96 TeV  

NASA Astrophysics Data System (ADS)

We present the first combined measurement of the rapidity and transverse momentum dependence of dijet azimuthal decorrelations, using the recently proposed quantity R??. The variable R?? measures the fraction of the inclusive dijet events in which the azimuthal separation of the two jets with the highest transverse momenta is less than a specified value of the parameter ??max. The quantity R?? is measured in ppbar collisions at ?{s}=1.96 TeV, as a function of the dijet rapidity interval, the total scalar transverse momentum, and ??max. The measurement uses an event sample corresponding to an integrated luminosity of 0.7 fb-1 collected with the D0 detector at the Fermilab Tevatron Collider. The results are compared to predictions of a perturbative QCD calculation at next-to-leading order in the strong coupling with corrections for non-perturbative effects. The theory predictions describe the data well, except in the kinematic region of large dijet rapidity intervals and small ??max.

Abazov, V. M.; Abbott, B.; Acharya, B. S.; Adams, M.; Adams, T.; Alexeev, G. D.; Alkhazov, G.; Alton, A.; Askew, A.; Atkins, S.; Augsten, K.; Avila, C.; Badaud, F.; Bagby, L.; Baldin, B.; Bandurin, D. V.; Banerjee, S.; Barberis, E.; Baringer, P.; Bartlett, J. F.; Bassler, U.; Bazterra, V.; Bean, A.; Begalli, M.; Bellantoni, L.; Beri, S. B.; Bernardi, G.; Bernhard, R.; Bertram, I.; Besançon, M.; Beuselinck, R.; Bhat, P. C.; Bhatia, S.; Bhatnagar, V.; Blazey, G.; Blessing, S.; Bloom, K.; Boehnlein, A.; Boline, D.; Boos, E. E.; Borissov, G.; Brandt, A.; Brandt, O.; Brock, R.; Bross, A.; Brown, D.; Brown, J.; Bu, X. B.; Buehler, M.; Buescher, V.; Bunichev, V.; Burdin, S.; Buszello, C. P.; Camacho-Pérez, E.; Casey, B. C. K.; Castilla-Valdez, H.; Caughron, S.; Chakrabarti, S.; Chakraborty, D.; Chakravarthula, K.; Chan, K. M.; Chandra, A.; Chapon, E.; Chen, G.; Cho, S. W.; Choi, S.; Choudhary, B.; Cihangir, S.; Claes, D.; Clutter, J.; Cooke, M.; Cooper, W. E.; Corcoran, M.; Couderc, F.; Cousinou, M.-C.; Cutts, D.; Das, A.; Davies, G.; de Jong, S. J.; De La Cruz-Burelo, E.; Déliot, F.; Demina, R.; Denisov, D.; Denisov, S. P.; Desai, S.; Deterre, C.; DeVaughan, K.; Diehl, H. T.; Diesburg, M.; Ding, P. F.; Dominguez, A.; Dubey, A.; Dudko, L. V.; Duggan, D.; Duperrin, A.; Dutt, S.; Dyshkant, A.; Eads, M.; Edmunds, D.; Ellison, J.; Elvira, V. D.; Enari, Y.; Evans, H.; Evdokimov, V. N.; Facini, G.; Feng, L.; Ferbel, T.; Fiedler, F.; Filthaut, F.; Fisher, W.; Fisk, H. E.; Fortner, M.; Fox, H.; Fuess, S.; Garcia-Bellido, A.; García-González, J. A.; García-Guerra, G. A.; Gavrilov, V.; Geng, W.; Gerber, C. E.; Gershtein, Y.; Ginther, G.; Golovanov, G.; Grannis, P. D.; Greder, S.; Greenlee, H.; Grenier, G.; Gris, Ph.; Grivaz, J.-F.; Grohsjean, A.; Grünendahl, S.; Grünewald, M. W.; Guillemin, T.; Gutierrez, G.; Gutierrez, P.; Haley, J.; Han, L.; Harder, K.; Harel, A.; Hauptman, J. M.; Hays, J.; Head, T.; Hebbeker, T.; Hedin, D.; Hegab, H.; Heinson, A. P.; Heintz, U.; Hensel, C.; Heredia-De La Cruz, I.; Herner, K.; Hesketh, G.; Hildreth, M. D.; Hirosky, R.; Hoang, T.; Hobbs, J. D.; Hoeneisen, B.; Hogan, J.; Hohlfeld, M.; Howley, I.; Hubacek, Z.; Hynek, V.; Iashvili, I.; Ilchenko, Y.; Illingworth, R.; Ito, A. S.; Jabeen, S.; Jaffré, M.; Jayasinghe, A.; Jeong, M. S.; Jesik, R.; Jiang, P.; Johns, K.; Johnson, E.; Johnson, M.; Jonckheere, A.; Jonsson, P.; Joshi, J.; Jung, A. W.; Juste, A.; Kajfasz, E.; Karmanov, D.; Kasper, P. A.; Katsanos, I.; Kehoe, R.; Kermiche, S.; Khalatyan, N.; Khanov, A.; Kharchilava, A.; Kharzheev, Y. N.; Kiselevich, I.; Kohli, J. M.; Kozelov, A. V.; Kraus, J.; Kumar, A.; Kupco, A.; Kur?a, T.; Kuzmin, V. A.; Lammers, S.; Landsberg, G.; Lebrun, P.; Lee, H. S.; Lee, S. W.; Lee, W. M.; Lei, X.; Lellouch, J.; Li, D.; Li, H.; Li, L.; Li, Q. Z.; Lim, J. K.; Lincoln, D.; Linnemann, J.; Lipaev, V. V.; Lipton, R.; Liu, H.; Liu, Y.; Lobodenko, A.; Lokajicek, M.; Lopes de Sa, R.; Luna-Garcia, R.; Lyon, A. L.; Maciel, A. K. A.; Magaña-Villalba, R.; Malik, S.; Malyshev, V. L.; Maravin, Y.; Martínez-Ortega, J.; McCarthy, R.; McGivern, C. L.; Meijer, M. M.; Melnitchouk, A.; Menezes, D.; Mercadante, P. G.; Merkin, M.; Meyer, A.; Meyer, J.; Miconi, F.; Mondal, N. K.; Mulhearn, M.; Nagy, E.; Naimuddin, M.; Narain, M.; Nayyar, R.; Neal, H. A.; Negret, J. P.; Neustroev, P.; Nguyen, H. T.; Nunnemann, T.; Orduna, J.; Osman, N.; Osta, J.; Padilla, M.; Pal, A.; Parashar, N.; Parihar, V.; Park, S. K.; Partridge, R.; Parua, N.; Patwa, A.; Penning, B.; Perfilov, M.; Peters, Y.; Petridis, K.; Petrillo, G.; Pétroff, P.; Pleier, M.-A.; Podesta-Lerma, P. L. M.; Podstavkov, V. M.; Popov, A. V.; Prewitt, M.; Price, D.; Prokopenko, N.; Qian, J.; Quadt, A.; Quinn, B.; Rangel, M. S.; Ranjan, K.; Ratoff, P. N.; Razumov, I.; Renkel, P.; Ripp-Baudot, I.; Rizatdinova, F.; Rominsky, M.; Ross, A.; Royon, C.; Rubinov, P.; Ruchti, R.; Sajot, G.; Salcido, P.; Sánchez-Hernández, A.; Sanders, M. P.; Santos, A. S.; Savage, G.; Sawyer, L.; Scanlon, T.; Schamberger, R. D.; Scheglov, Y.; Schellman, H.; Schwanenberger, C.; Schwienhorst, R.; Sekaric, J.; Severini, H.; Shabalina, E.; Shary, V.; Shaw, S.; Shchukin, A. A.; Shivpuri, R. K.; Simak, V.; Skubic, P.; Slattery, P.; Smirnov, D.; Smith, K. J.; Snow, G. R.; Snow, J.; Snyder, S.; Söldner-Rembold, S.; Sonnenschein, L.; Soustruznik, K.; Stark, J.; Stoyanova, D. A.; Strauss, M.; Suter, L.; Svoisky, P.; Titov, M.; Tokmenin, V. V.; Tsai, Y.-T.; Tsybychev, D.; Tuchming, B.; Tully, C.; Uvarov, L.; Uvarov, S.; Uzunyan, S.; Van Kooten, R.; van Leeuwen, W. M.; Varelas, N.; Varnes, E. W.; Vasilyev, I. A.; Verdier, P.; Verkheev, A. Y.; Vertogradov, L. S.; Verzocchi, M.; Vesterinen, M.; Vilanova, D.; Vokac, P.; Wahl, H. D.; Wang, M. H. L. S.; Warchol, J.; Watts, G.; Wayne, M.; Weichert, J.

2013-04-01

31

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

SciTech Connect

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

STAR Collaboration; Abelev, Betty

2010-07-05

32

Mixed harmonic charge dependent azimuthal correlations in Pb-Pb collisions at $\\sqrt{s_{NN}}$ = 2.76 TeV measured with the ALICE experiment at the LHC  

E-print Network

Mixed harmonic charge dependent azimuthal correlations at mid-rapidity in Pb-Pb collisions at $\\sqrt{s_{NN}}$ = 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.

Yasuto Hori; for the ALICE Collaboration

2012-11-07

33

Time-dependent angularly averaged inverse transport  

E-print Network

This paper concerns the reconstruction of the absorption and scattering parameters in a time-dependent linear transport equation from knowledge of angularly averaged measurements performed at the boundary of a domain of interest. We show that the absorption coefficient and the spatial component of the scattering coefficient are uniquely determined by such measurements. We obtain stability results on the reconstruction of the absorption and scattering parameters with respect to the measured albedo operator. The stability results are obtained by a precise decomposition of the measurements into components with different singular behavior in the time domain.

Guillaume Bal; Alexandre Jollivet

2009-02-19

34

Spin Dependent Transport in Novel Magnetic Heterostructures  

NASA Astrophysics Data System (ADS)

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

Jayathilaka, Priyanga Buddhika

35

Dependence of enhanced asymmetry-induced transport on collision frequency  

NASA Astrophysics Data System (ADS)

Our previous studiesfootnotetextD. L. Eggleston, Phys. Plasmas 19, 042307 (2012). of asymmetry-induced radial transport using a single-particle code with collisional effects have identified, for asymmetries of the form ?1(r)(kz)(?t - l?), two sources for the transport: resonant particles (RPs) and axially trapped particles (ATPs). We observe that this latter type, which occurs near the radius where ? matches the azimuthal rotation frequency ?R, is often dominant at low collision frequency ? but becomes negligible at higher ?. This can be understood by noting that ATPs have a lower trapping frequency ?T^2= (l^2?1/rB)|d?R/dr| than RPs. In the low ? (banana) regime, the radial oscillations have amplitude ?r= vr/?T, so ATPs dominate, and the transport may even exceed the RP plateau regime level. As ? increases, collisions start to interrupt the slower ATP oscillations while the RPs are still in the banana regime, so the ATP contribution to the transport decreases. At the largest ? values, ATP transport is negligible and the observed diffusion coefficient matches that given by plateau regime RP theory.footnotetextD. L. Eggleston and T. M. O'Neil, Phys. Plasmas 6, 2699 (1999).

Eggleston, D. L.

2012-10-01

36

Reconstitution of microtubule-dependent organelle transport.  

PubMed

Microtubule (MT)-based motor proteins transport many cellular factors to their functionally relevant locations within cells, and defects in transport are linked to human disease. Understanding the mechanism and regulation of this transport process in living cells is difficult because of the complex in vivo environment and limited means to manipulate the system. On the other hand, in vitro motility assays using purified motors attached to beads does not recapitulate the full complexity of cargo transport in vivo. Assaying motility of organelles in cell extracts is therefore attractive, as natural cargoes are being examined, but in an environment that is more amenable to manipulation. Here, we describe the purification and in vitro MT-based motility of phagosomes from Dictyostelium and lipid droplets from rat liver. These assays have the potential to address diverse questions related to endosome/phagosome maturation, fatty acid regulation, and could also serve as a starting point for reconstituting the motility of other types of organelles. PMID:24630110

Barak, Pradeep; Rai, Ashim; Dubey, Alok Kumar; Rai, Priyanka; Mallik, Roop

2014-01-01

37

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

38

Spin dependent transport effects in Cu nanowires  

NASA Astrophysics Data System (ADS)

In this work we investigate quantum transport in Cu nanowires created by bringing macroscopic Cu wires into and out of contact under an applied magnetic field in air. Here we show that a 70% magnetoconductance effect can be seen in a Cu nanowire in a field of 2 mT at room temperature. We propose that this phenomenon is a consequence of spin filtering due to the adsorption of atmospheric oxygen modifying the electronic band structure and introducing spin split conduction channels. Since bulk Cu is not magnetic it may provide a new perspective for spintronics.

Gillingham, D. M.; Müller, C.; Bland, J. A. C.

2004-06-01

39

Spin-dependent transport in magnetic nanostructures  

Microsoft Academic Search

The charging energy of a metallic grain called a dot embedded in a nanowire causes the single electron tunneling. We propose that when two magnetic dots are embedded in a nanowire, the single electron tunneling process is controlled by an external magnetic field. This is because the tunneling of electrons between magnetic dots depends on the relative angle of the

S. Maekawa; J. Inoue

1996-01-01

40

Azimuth and Altitude  

NSDL National Science Digital Library

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

41

Time-dependent density functional theory for quantum transport  

NASA Astrophysics Data System (ADS)

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

Kwok, Yanho; Zhang, Yu; Chen, GuanHua

2014-12-01

42

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

43

Temperature dependence of the ballistic energy transport in perfluoroalkanes.  

PubMed

Temperature dependence of intramolecular energy transport in perfluoroalkane oligomers with a chain length of 3-11 carbon atoms terminated by a carboxylic acid moiety on one end and a -CF2H group on another end was studied in solution experimentally and theoretically. Experiments were performed using a dual-frequency relaxation-assisted two-dimensional infrared spectroscopy method. The energy transport was initiated by exciting the C?O stretching mode of the acid and recorded by measuring a cross-peak amplitude between the C?O stretching and the C-H bending modes as a function of the waiting time between the excitation and probing. An efficient transport regime with a mean free path of 16.4 ± 2 Å is observed at 35 °C. The energy transport speed decreases at elevated temperatures, indicating a switch from the ballistic transport regime to diffusive. The modeling of the energy transport involving both ballistic and diffusive mechanisms is performed. It explains the temperature dependence of the energy transport speed and confirms a switch of the transport regime from ballistic at lower temperatures to diffusive at higher temperatures. PMID:24697782

Rubtsova, Natalia I; Kurnosov, Arkady A; Burin, Alexander L; Rubtsov, Igor V

2014-07-17

44

Azimuthal Anisotropy and the QGP  

SciTech Connect

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

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

2006-11-02

45

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

46

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

47

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

48

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

SciTech Connect

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

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

2014-01-15

49

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

NASA Astrophysics Data System (ADS)

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

Dumbrajs, O.; Avramidis, K. A.; Franck, J.; Jelonnek, J.

2014-01-01

50

Voltage-dependent phosphate transport in osteoblast-like cells.  

PubMed

Phosphate ion (Pi) in sufficient concentrations is crucial for bone mineralization. The osteoblast (OB) may be responsible for the transport of Pi into the bone interstitium, where mineralization occurs. We previously characterized a Na(+)-dependent Pi transporter (NaPi) in the osteoblastic UMR-106-01 cell line. In the present study, the alteration of Na(+)-dependent Pi transport by changes in membrane potential was investigated. Depolarizing the cells with increasing concentrations of ambient K+ and valinomycin resulted in a progressive decline in Na(+)-dependent Pi uptake to a maximum of 28% at a membrane potential of -18 mV compared to control Na(+)-dependent Pi uptake at a membrane potential of approximately -60 mV. Hyperpolarizing the cells with SCN- increased Na(+)-dependent Pi uptake over control by 50% at an SCN- concentration of 70 mM. Determination of membrane potential by using the fluorescent probe, DiSC3(5), showed that the addition of Pi to cells in Na(+)-containing medium resulted in a small depolarization. These data show that NaPi activity can be altered by membrane potential changes and that the initiation of Na(+)-dependent Pi uptake is associated with depolarization of the plasma membrane of UMR-106-01 cells. Taken together, the cotransport of Na+ and Pi results in the movement of a net positive charge into the cell. PMID:1805540

Luong, K V; Green, J; Kleeman, C R; Yamaguchi, D T

1991-11-01

51

Diameter Dependence of the Transport Properties of Antimony Telluride Nanowires  

E-print Network

Diameter Dependence of the Transport Properties of Antimony Telluride Nanowires Yuri M. Zuev, Jin properties of individual single crystal antimony telluride (Sb2Te3) nanowires with diameters in the range figure of merit in single crystal chalcogenide Sb2Te3 NWs. Antimony telluride (Sb2Te3) is a small bandgap

Heller, Eric

52

Frequency dependence of anomalous transport in field theory and holography  

NASA Astrophysics Data System (ADS)

We study the frequency dependence of anomalous transport coefficients for a relativistic gas of free chiral fermions and for a strongly coupled conformal field theory with holographic dual. We perform the computation by using the Kubo formulae for- malism, and compare with a hydrodynamic calculation of two point functions. Some implications for heavy ion physics are discussed.

Megías, Eugenio; Pena-Benitez, Francisco

2014-11-01

53

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

54

Particle-type dependence of azimuthal anisotropy and nuclear modification of particle production in Au+Au collisions at square root of sNN=200 GeV.  

PubMed

We present STAR measurements of the azimuthal anisotropy parameter v(2) and the binary-collision scaled centrality ratio R(CP) for kaons and lambdas (Lambda+Lambda) at midrapidity in Au+Au collisions at square root of s(NN)=200 GeV. In combination, the v(2) and R(CP) particle-type dependencies contradict expectations from partonic energy loss followed by standard fragmentation in vacuum. We establish p(T) approximately 5 GeV/c as the value where the centrality dependent baryon enhancement ends. The K(0)(S) and Lambda+Lambda v(2) values are consistent with expectations of constituent-quark-number scaling from models of hadron formation by parton coalescence or recombination. PMID:14995300

Adams, J; Adler, C; Aggarwal, M M; Ahammed, Z; Amonett, J; Anderson, B D; Anderson, M; Arkhipkin, D; Averichev, G S; Badyal, S K; Balewski, J; Barannikova, O; Barnby, L S; Baudot, J; Bekele, S; Belaga, V V; Bellwied, R; Berger, J; Bezverkhny, B I; Bhardwaj, S; Bhaskar, P; Bhati, A K; Bichsel, H; Billmeier, A; Bland, L C; Blyth, C O; Bonner, B E; Botje, M; Boucham, A; Brandin, A; Bravar, A; Cadman, R V; Cai, X Z; Caines, H; Calderón de la Barca Sánchez, M; Carroll, J; Castillo, J; Castro, M; Cebra, D; Chaloupka, P; Chattopadhyay, S; Chen, H F; Chen, Y; Chernenko, S P; Cherney, M; Chikanian, A; Choi, B; Christie, W; Coffin, J P; Cormier, T M; Cramer, J G; Crawford, H J; Das, D; Das, S; Derevschikov, A A; Didenko, L; Dietel, T; Dong, W J; Dong, X; Draper, J E; Du, F; Dubey, A K; Dunin, V B; Dunlop, J C; Dutta Majumdar, M R; Eckardt, V; Efimov, L G; Emelianov, V; Engelage, J; Eppley, G; Erazmus, B; Estienne, M; Fachini, P; Faine, V; Faivre, J; Fatemi, R; Filimonov, K; Filip, P; Finch, E; Fisyak, Y; Flierl, D; Foley, K J; Fu, J; Gagliardi, C A; Gagunashvili, N; Gans, J; Ganti, M S; Gaudichet, L; Germain, M; Geurts, F; Ghazikhanian, V; Ghosh, P; Gonzalez, J E; Grachov, O; Grigoriev, V; Gronstal, S; Grosnick, D; Guedon, M; Guertin, S M; Gupta, A; Gushin, E; Gutierrez, T D; Hallman, T J; Hardtke, D; Harris, J W; Heinz, M; Henry, T W; Heppelmann, S; Herston, T; Hippolyte, B; Hirsch, A; Hjort, E; Hoffmann, G W; Horsley, M; Huang, H Z; Huang, S L; Humanic, T J; Igo, G; Ishihara, A; Jacobs, P; Jacobs, W W; Janik, M; Jiang, H; Johnson, I; Jones, P G; Judd, E G; Kabana, S; Kaneta, M; Kaplan, M; Keane, D; Khodyrev, V Yu; Kiryluk, J; Kisiel, A; Klay, J; Klein, S R; Klyachko, A; Koetke, D D; Kollegger, T; Kopytine, M; Kotchenda, L; Kovalenko, A D; Kramer, M; Kravtsov, P; Kravtsov, V I; Krueger, K; Kuhn, C; Kulikov, A I; Kumar, A; Kunde, G J; Kunz, C L; Kutuev, R Kh; Kuznetsov, A A; Lamont, M A C; Landgraf, J M; Lange, S; Lansdell, C P; Lasiuk, B; Laue, F; Lauret, J; Lebedev, A; Lednický, R; LeVine, M J; Li, C; Li, Q; Lindenbaum, S J; Lisa, M A; Liu, F; Liu, L; Liu, Z; Liu, Q J; Ljubicic, T; Llope, W J; Long, H; Longacre, R S; Lopez-Noriega, M; Love, W A; Ludlam, T; Lynn, D; Ma, J; Ma, Y G; Magestro, D; Mahajan, S; Mangotra, L K; Mahapatra, D P; Majka, R; Manweiler, R; Margetis, S; Markert, C; Martin, L; Marx, J; Matis, H S; Matulenko, Yu A; McShane, T S; Meissner, F; Melnick, Yu; Meschanin, A; Messer, M; Miller, M L; Milosevich, Z; Minaev, N G; Mironov, C; Mishra, D; Mitchell, J; Mohanty, B; Molnar, L; Moore, C F; Mora-Corral, M J; Morozov, D A; Morozov, V; de Moura, M M; Munhoz, M G; Nandi, B K; Nayak, S K; Nayak, T K; Nelson, J M; Nevski, P; Nikitin, V A; Nogach, L V; Norman, B; Nurushev, S B; Odyniec, G; Ogawa, A; Okorokov, V; Oldenburg, M; Olson, D; Paic, G; Pandey, S U; Pal, S K; Panebratsev, Y; Panitkin, S Y; Pavlinov, A I; Pawlak, T; Perevoztchikov, V; Perkins, C; Peryt, W; Petrov, V A; Phatak, S C; Picha, R; Planinic, M; Pluta, J; Porile, N; Porter, J; Poskanzer, A M; Potekhin, M; Potrebenikova, E; Potukuchi, B V K S; Prindle, D; Pruneau, C; Putschke, J; Rai, G; Rakness, G; Raniwala, R; Raniwala, S; Ravel, O; Ray, R L; Razin, S V; Reichhold, D; Reid, J G; Renault, G; Retiere, F; Ridiger, A; Ritter, H G; Roberts, J B; Rogachevski, O V; Romero, J L; Rose, A; Roy, C; Ruan, L J; Sahoo, R; Sakrejda, I; Salur, S; Sandweiss, J; Savin, I; Schambach, J; Scharenberg, R P; Schmitz, N; Schroeder, L S; Schweda, K; Seger, J; Seliverstov, D; Seyboth, P; Shahaliev, E; Shao, M; Sharma, M; Shestermanov, K E; Shimanskii, S S; Singaraju, R N; Simon, F; Skoro, G; Smirnov, N; Snellings, R; Sood, G; Sorensen, P; Sowinski, J; Spinka, H M; Srivastava, B; Stanislaus, S; Stock, R; Stolpovsky, A; Strikhanov, M; Stringfellow, B; Struck, C; Suaide, A A P; Sugarbaker, E; Suire, C; Sumbera, M; Surrow, B; Symons, T J M; de Toledo, A Szanto; Szarwas, P; Tai, A; Takahashi, J; Tang, A H; Thein, D; Thomas, J H; Tikhomirov, V; Tokarev, M; Tonjes, M B; Trainor, T A; Trentalange, S; Tribble, R E; Trivedi, M D; Trofimov, V; Tsai, O; Ullrich, T; Underwood, D G; Van Buren, G; VanderMolen, A M; Vasiliev, A N; Vasiliev, M; Vigdor, S E; Viyogi, Y P; Voloshin, S A; Waggoner, W; Wang, F; Wang, G; Wang, X L; Wang, Z M; Ward, H; Watson, J W; Wells, R; Westfall, G D; Whitten, C; Wieman, H; Willson, R; Wissink, S W; Witt, R; Wood, J; Wu, J; Xu, N; Xu, Z; Xu, Z Z; Yamamoto, E; Yepes, P; Yurevich, V I; Zanevski, Y V; Zborovský, I; Zhang, H; Zhang, W M; Zhang, Z P; Zo?nierczuk, P A; Zoulkarneev, R; Zoulkarneeva, J; Zubarev, A N

2004-02-01

55

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

56

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

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

57

Anomeric dependence of fluorodeoxyglucose transport in human erythrocytes.  

PubMed

The transport of several n-fluoro-n-deoxy-D-glucose derivatives across the human erythrocyte membrane has been studied under equilibrium exchange conditions using one- and two-dimensional nuclear magnetic resonance (NMR) techniques. This approach is based on the intracellular 19F shift, which was found to depend on the anomeric form and on the F/OH substitution position. Since the transport behavior of both glucose anomers can be followed simultaneously, this approach is particularly sensitive to differences in anomeric permeability. For 2-, 3-, 4-, and 6-fluorodeoxyglucose analogs, the alpha anomers permeate more rapidly, and the P alpha/P beta ratio is dependent on the position of fluorination, with values of 1.1, 1.3, 2.5, and 1.6, respectively, obtained at 37 degrees C. These results have been analyzed in terms of a simple alternating conformation model for the glucose transporter. Although mutarotase activity has been reported for red cells, mutarotation behavior for all anomers was found to be completely negligible on the transport and spin-lattice relaxation time scales. Metabolic transformation of the fluorinated glucose analogs, primarily to fluorinated gluconate and sorbitol analogs, is very slow and does not significantly interfere with the transport measurements. A mean ratio of 2.6 was found for the extracellular/intracellular fluorine spin-lattice relaxation rates. PMID:8086416

O'Connell, T M; Gabel, S A; London, R E

1994-09-13

58

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

59

Azimuthally Sensitive Femtoscopy and {nu}2  

SciTech Connect

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

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

2006-04-11

60

Technology of optical azimuth transmission  

NASA Astrophysics Data System (ADS)

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

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

2012-11-01

61

Temperature dependent transport coefficients in a dynamical holographic QCD model  

E-print Network

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

Danning Li; Song He; Mei Huang

2014-11-19

62

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

SciTech Connect

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

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

2010-10-01

63

Molecular spintronics: spin-dependent electron transport in molecular wires  

Microsoft Academic Search

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

Eldon G. Emberly; George Kirczenow

2002-01-01

64

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

PubMed

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

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

2003-10-01

65

Transport of hydrogen in metals with occupancy dependent trap energies  

SciTech Connect

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

2014-10-07

66

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

67

Regulation of sodium-dependent phosphate transport in osteoclasts.  

PubMed Central

Osteoclasts are the primary cells responsible for bone resorption. They are exposed to high ambient concentrations of inorganic phosphate (Pi) during the process of bone resorption and they possess specific Pi-transport system(s) capable of taking up Pi released by bone resorption. By immunochemical studies and PCR, we confirmed previous studies suggesting the presence of an Na-dependent Pi transporter related to the renal tubular "NaPi" proteins in the osteoclast. Using polyclonal antibodies to NaPi-2 (the rat variant), an approximately 95-kD protein was detected, localized in discrete vesicles in unpolarized osteoclasts cultured on glass coverslips. However, in polarized osteoclasts cultured on bone, immunofluorescence studies demonstrated the protein to be localized exclusively on the basolateral membrane, where it colocalizes with an Na-H exchanger but opposite to localization of the vacuolar H-ATPase. An inhibitor of phosphatidylinositol 3-kinase, wortmannin, and an inhibitor of actin cytoskeletal organization, cytochalasin D, blocked the bone-stimulated increase in Pi uptake. Phosphonoformic acid (PFA), an inhibitor of the renal NaPi-cotransporter, reduced NaPi uptake in the osteoclast. PFA also elicited a dose-dependent inhibition of bone resorption. PFA limited ATP production in osteoclasts attached to bone particles. Our results suggest that Pi transport in the osteoclast is a process critical to the resorption of bone through provision of necessary energy substrates. PMID:9239400

Gupta, A; Guo, X L; Alvarez, U M; Hruska, K A

1997-01-01

68

Aspects of Tmd Evolution of Azimuthal Asymmetries  

NASA Astrophysics Data System (ADS)

In this contribution TMD evolution of azimuthal asymmetries, in particular of the Sivers and double Collins asymmetries, is addressed. A comparison of the scale dependence is made between asymmetries described with TMD factorization at low transverse momentum and those described with collinear factorization at high transverse momentum. Finally, the advantages of Bessel weighting are discussed: convergence of transverse momentum integrals, suppression of large transverse momentum contributions, and well-defined lattice QCD evaluations of Bessel-weighted TMDs including proper gauge links.

Boer, Daniël

2014-01-01

69

Activity-Dependent Regulation of Surface Glucose Transporter-3  

PubMed Central

Glucose transporter 3 (GLUT3) is the main facilitative glucose transporter in neurons. Glucose provides neurons with a critical energy source for neuronal activity. However, the mechanism by which neuronal activity controls glucose influx via GLUT3 is unknown. We investigated the influence of synaptic stimulation on GLUT3 surface expression and glucose import in primary cultured cortical and hippocampal neurons. Synaptic activity increased surface expression of GLUT3 leading to an elevation of intracellular glucose. The effect was blocked by N-Methyl-D-Aspartate receptor (NMDAR) and neuronal nitric oxide synthase (nNOS) inhibition. The Akt Inhibitor, Akt-I blocked NMDAR-induced GLUT3 surface expression while a nNOS-phosphomimetic mutant (S1412D) enhanced GLUT3 expression at cell surface. These results suggest that NMDAR/Akt-dependent nNOS phosphorylation is coupled to GLUT3 trafficking. We demonstrated that activation of cGMP-dependent protein kinase (cGK) increased the surface expression of GLUT3, which was repressed by Rp-8-pCPT-cGMPS, a potent cell permeable inhibitor of cGKs. These studies characterize the molecular basis for activity dependent increases in surface GLUT3 after stimulation of the NMDARs. NMDAR-induced increase in surface GLUT3 represents a novel pathway for control of energy supply during neuronal activity that is critical for maintaining glucose homeostasis during neuronal transmission. PMID:21307237

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

2011-01-01

70

Influences of electron spin ordering on spin dependent transport  

NASA Astrophysics Data System (ADS)

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

Miao, Guo-Xing

71

Azimuthal Asymmetry and Transverse Momentum in Deep Inelastic Muon Scattering  

E-print Network

The azimuthal asymmetry and the transverse momentum of forward produced charged hadrons in deep inelastic muon scattering have been studied as a function of the event kinematics and of the hadron variables. Primordial $k_T$ of the struck parton and O($\\alpha_s$) corrections to the cross-section are expected to contribute to the transverse momentum and the azimuthal asymmetry of hadrons. The data show some unexpected dependences not present in a Monte Carlo simulation which includes the theoretical parton-level azimuthal asymmetry.

Mark D. Baker for the Fermilab E665 Collaboration

2013-12-17

72

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

PubMed Central

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

Anwer, M. Sawkat; Stieger, Bruno

2013-01-01

73

Sodium-dependent bile salt transporters of the SLC10A transporter family: more than solute transporters.  

PubMed

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

Anwer, M Sawkat; Stieger, Bruno

2014-01-01

74

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.; Löwen, H.

2003-01-01

75

Heat generation and transport due to time-dependent forces  

NASA Astrophysics Data System (ADS)

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

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

2011-10-01

76

Type IIc Sodium–Dependent Phosphate Transporter Regulates Calcium Metabolism  

PubMed Central

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 D3 levels, but they did not develop hypophosphatemia, hyperphosphaturia, renal calcification, rickets, or osteomalacia. The increased levels of 1,25-dihydroxyvitamin D3 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 1?-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

77

Measurement of the azimuthal angle dependence of inclusive jet yields in Pb+Pb collisions at ?(sNN)=2.76 TeV with the ATLAS detector.  

PubMed

Measurements of the variation of inclusive jet suppression as a function of relative azimuthal angle, ??, with respect to the elliptic event plane provide insight into the path-length dependence of jet quenching. ATLAS has measured the ?? dependence of jet yields in 0.14 nb(-1) of ?(s(NN))=2.76 TeV Pb+Pb collisions at the LHC for jet transverse momenta p(T)>45 GeV in different collision centrality bins using an underlying event subtraction procedure that accounts for elliptic flow. The variation of the jet yield with ?? was characterized by the parameter, v(2)(jet), and the ratio of out-of-plane (??~?/2) to in-plane (??~0) yields. Nonzero v(2)(jet) values were measured in all centrality bins for p(T)<160 GeV. The jet yields are observed to vary by as much as 20% between in-plane and out-of-plane directions. PMID:24160592

Aad, G; Abajyan, T; Abbott, B; Abdallah, J; Abdel Khalek, S; Abdinov, O; Aben, R; Abi, B; Abolins, M; AbouZeid, O S; Abramowicz, H; Abreu, H; Abulaiti, Y; Acharya, B S; Adamczyk, L; Adams, D L; Addy, T N; Adelman, J; Adomeit, S; Adye, T; Aefsky, S; Agatonovic-Jovin, T; Aguilar-Saavedra, J A; Agustoni, M; Ahlen, S P; Ahmad, A; Ahsan, M; Aielli, G; Akesson, T P A; Akimoto, G; Akimov, A V; Alam, M A; Albert, J; Albrand, S; Alconada Verzini, M J; Aleksa, M; Aleksandrov, I N; Alessandria, F; Alexa, C; Alexander, G; Alexandre, G; Alexopoulos, T; Alhroob, M; Aliev, M; Alimonti, G; Alio, L; Alison, J; Allbrooke, B M M; Allison, L J; Allport, P P; Allwood-Spiers, S E; Almond, J; Aloisio, A; Alon, R; Alonso, A; Alonso, F; Altheimer, A; Alvarez Gonzalez, B; Alviggi, M G; Amako, K; Amaral Coutinho, Y; Amelung, C; Ammosov, V V; Amor Dos Santos, S P; Amorim, A; Amoroso, S; Amram, N; Anastopoulos, C; Ancu, L S; Andari, N; Andeen, T; Anders, C F; Anders, G; Anderson, K J; Andreazza, A; Andrei, V; Anduaga, X S; Angelidakis, S; Anger, P; Angerami, A; Anghinolfi, F; Anisenkov, A V; Anjos, N; Annovi, A; Antonaki, A; Antonelli, M; Antonov, A; Antos, J; Anulli, F; Aoki, M; Aperio Bella, L; Apolle, R; Arabidze, G; Aracena, I; Arai, Y; Arce, A T H; Arfaoui, S; Arguin, J-F; Argyropoulos, S; Arik, E; Arik, M; Armbruster, A J; Arnaez, O; Arnal, V; Artamonov, A; Artoni, G; Arutinov, D; Asai, S; Asbah, N; Ask, S; 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; Bruncko, D; Bruneliere, R; Brunet, S; Bruni, A; Bruni, G; Bruschi, M; Bryngemark, L; Buanes, T; Buat, Q; Bucci, F; Buchanan, J; Buchholz, P; Buckingham, R M; Buckley, A G; Buda, S I; Budagov, I A; Budick, B; Bugge, L; Bulekov, O; Bundock, A C; Bunse, M; Buran, T; Burckhart, H; Burdin, S; Burgess, T; Burke, S; Busato, E; Büscher, V; Bussey, P; Buszello, C P; Butler, B; Butler, J M; Buttar, C M; Butterworth, J M; Buttinger, W; Byszewski, M; Cabrera Urbán, S; Caforio, D; Cakir, O; Calafiura, P; Calderini, G

2013-10-11

78

Precision stationkeeping with azimuthing thrusters  

E-print Network

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

Doroski, Adam D

2011-01-01

79

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

80

Time dependent neutral gas transport in tokamak edge plasmas  

NASA Astrophysics Data System (ADS)

The effects of neutral particles on the edge plasma conditions play a key role in divertor and limiter physics. In computational models they are usually treated in steady state approximation (instantaneous relaxation). However, the characteristics transport time scale is comparable to the ion acustic time scale. Thus neutral atoms relax to their steady state distributions much slower than electron temperature profiles along the fieldlines are established. A computational assessment of divertor or limiter dynamics requires ultimately an extension to time dependent algorithms. The numerical procedure in the EIRENE Monte Carlo code is presented. A first numerical study of ELM's in the ASDEX-Upgrade divertor plasma has been carried out and the results are briefly discussed.

Reiter, D.; May, Chr.; Coster, D.; Schneider, R.

1995-04-01

81

Vector correlations in dissociative photoionization of O2 in the 20-28 eV range. II. Polar and azimuthal dependence of the molecular frame photoelectron angular distribution  

NASA Astrophysics Data System (ADS)

A combined experimental and theoretical study of the polar and azimuthal dependence of the molecular frame photoelectron angular distributions (MFPADs) for inner-valence-shell photoionization of the O2 molecule into the O2+(B 2Sigmag-,3 2Piu,c 4Sigmau)- states is reported. The measured MFPADs, for each orientation of the molecular axis with respect to the linear polarization of the synchrotron radiation, are derived from the spatial analysis of the (VO+,Ve),P vector correlation, where the nascent ion and electron velocity vectors VO+ and Ve are determined for each dissociative photoionization (DPI) event using imaging and time of flight resolved coincidence technique as described in the companion paper of this series [J. Chem. Phys. 114, 6605 (2001)]. Expressed in the general form of four FLN(thetae) functions which contain all the dynamical information about the photoionization processes, they are compared with the MFPADs computed using the multichannel Schwinger configuration interaction method. A very satisfactory agreement is found. When the lifetime of the O2+ ionic states is a significant fraction of the rotational period, the rotational motion of the molecule is included in the quantal derivation of the MFPADs. Measured MFPADs are also reported for the additional DPI process identified in Paper I, and for DPI involving the excitation of the neutral (3 2Pi]u,4s[sigmag) Rydberg state.

Lafosse, A.; Brenot, J. C.; Guyon, P. M.; Houver, J. C.; Golovin, A. V.; Lebech, M.; Dowek, D.; Lin, P.; Lucchese, R. R.

2002-11-01

82

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

NSDL National Science Digital Library

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

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

2006-04-01

83

Functional dependence of the exact time-dependent Kohn-Sham potential for quantum transport  

NASA Astrophysics Data System (ADS)

We present methods for determining exact steady-state and time-dependent Kohn-Sham potentials from known charge and current densities. Applying these methods to cases of a single electron added to the conduction band of a model semiconductor, we calculate the exact Kohn-Sham potentials and discuss their meaning in the context of describing quantum transport. We show that the inclusion of a longitudinal Kohn-Sham vector potential is quite unavoidable in describing steady-state current-carrying systems, whereas the addition of an electron in a wavepacket state necessitates, inter alia, the appearance of an exchange-correlation electric field. We also present our findings on the functional dependence of the exact Kohn-Sham scalar and vector potentials on the charge and current density.

Ramsden, James; Godby, Rex

2012-02-01

84

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

85

Gymnemic acids inhibit sodium-dependent glucose transporter 1.  

PubMed

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

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

2014-06-25

86

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

87

Temperature-dependent thermal transport properties of Archean rocks  

NASA Astrophysics Data System (ADS)

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

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

2010-12-01

88

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

89

Anomalous diameter dependence of thermal transport in ultra-narrow Si nanowires  

E-print Network

transport, long wavelength phonons. #12;2 I. Introduction In bulk semiconductors and insulators the thermal1 Anomalous diameter dependence of thermal transport in ultra-narrow Si nanowires Hossein calculations of thermal transport in Si nanowires of diameters from 12nm down to 1nm. We show

90

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

E-print Network

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

Grosell, Martin

91

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

92

Azimuthal anisotropy: The higher harmonics  

SciTech Connect

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

Poskanzer, Arthur M.; STAR Collaboration

2004-03-12

93

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

94

Improvement of Azimuthator Based on Particle Simulation  

NASA Astrophysics Data System (ADS)

The azimuthator is an important part of plasma optical mass separation. The existing design for an azimuthator is based on the single particle orbit theory and focused on the movement of ions. In this paper, the particle simulation method is adopted to study the behavior of plasma crossing an azimuthator. The results show that electrons are bounded at the entrance of the azimuthator and an axial electric field is produced due to the charge separation. In order to better achieve the function of the azimuthator, a cathode is designed to transmit the electrons and to obtain a quasi-neutral plasma beam.

Zhao, Hailong; Wang, Chunsheng; Yan, Yuming; Liu, Hongchen; Jiang, Binhao

2015-01-01

95

Mode switching in a gyrotron with azimuthally corrugated resonator.  

PubMed

The operation of a gyrotron having a cylindrical resonator with an azimuthally corrugated wall is analyzed. In such a device, wall corrugation cancels the degeneracy of the modes with azimuthally standing patterns. The coupling between these modes depends on the radius of electron beam. It is shown that such a gyrotron can be easily switched from one mode to another. When the switching is done with the repetition frequency equal to the rotational frequency of magnetic islands, this sort of operation can be used for suppression of neoclassical tearing modes in large-scale tokamaks and stellarators. PMID:17677705

Nusinovich, G S; Sinitsyn, O V; Antonsen, T M

2007-05-18

96

Mode Switching in a Gyrotron with Azimuthally Corrugated Resonator  

SciTech Connect

The operation of a gyrotron having a cylindrical resonator with an azimuthally corrugated wall is analyzed. In such a device, wall corrugation cancels the degeneracy of the modes with azimuthally standing patterns. The coupling between these modes depends on the radius of electron beam. It is shown that such a gyrotron can be easily switched from one mode to another. When the switching is done with the repetition frequency equal to the rotational frequency of magnetic islands, this sort of operation can be used for suppression of neoclassical tearing modes in large-scale tokamaks and stellarators.

Nusinovich, G. S.; Sinitsyn, O. V.; Antonsen, T. M. Jr. [IREAP, University of Maryland, College Park, Maryland 20742-3511 (United States)

2007-05-18

97

Scatterometer azimuthal response and wind wave directionality  

NASA Technical Reports Server (NTRS)

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

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

1989-01-01

98

Expression of a rat renal sodium-dependent dicarboxylate transporter in Xenopus oocytes.  

PubMed Central

Microinjection of mRNA isolated from rat kidney cortex into Xenopus laevis oocytes resulted in the expression of a Na(+)-dependent dicarboxylate transporter, as detected by uptake measurements with [14C]succinate as substrate. The expressed transporter showed an S-shaped Na(+)-dependence with half-maximal activation at 19-21 mM Na+ and a Hill coefficient between 2 and 3. Endogenous succinate uptake was not Na(+)-dependent. Na(+)-stimulated succinate uptake in mRNA-injected oocytes exhibited a maximum at pH 7.5, whereas endogenous Na(+)-independent transporter was fastest at pH 8.5. The expressed dicarboxylate transporter also differed from the endogenous transporter in its sensitivity to citrate as well as dicarboxylates in trans and cis configurations. The expressed transporter resembled the renal basolateral transporter, especially with respect to affinity for succinate (Km 28 microM), activation by Na+, pH-dependence and substrate specificity. After injection of size-fractionated mRNA, succinate uptake was expressed by mRNA of 2-3 kb. Our results suggest expression of the basolateral Na(+)-dependent dicarboxylate transporter after injection of mRNA from rat kidney into Xenopus oocytes. PMID:8280108

Steffgen, J; Kienle, S; Scheyerl, F; Franz, H E

1994-01-01

99

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

PubMed

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

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

2014-12-01

100

Azimuthal Jet Tomography at RHIC and LHC  

E-print Network

A generic jet-energy loss model that is coupled to state-of-the-art hydrodynamic fields and interpolates between a wide class of running coupling pQCD-based and AdS/CFT-inspired models is compared to recent data on the azimuthal and transverse momentum dependence of high-pT pion nuclear modification factors and high-pT elliptic flow measured at RHIC and LHC. We find that RHIC data are surprisingly consistent with various scenarios considered. However, extrapolations to LHC energies favor running coupling pQCD-based models of jet-energy loss. While conformal holographic models are shown to be inconsistent with data, recent non-conformal generalizations of AdS holography may provide an alternative description.

Barbara Betz; Miklos Gyulassy

2014-02-14

101

Functional characterization of a Na+-dependent aspartate transporter from Pyrococcus horikoshii.  

PubMed

Excitatory amino acid transporters (EAATs) are crucial in maintaining extracellular levels of glutamate, the most abundant excitatory neurotransmitter, below toxic levels. The recent three-dimensional crystal structure of GltPh, an archaeal homolog of the EAATs, provides elegant structural details of this family of proteins, yet we know little about the mechanism of the bacterial transporter. Conflicting reports in the literature have described GltPh as an aspartate transporter driven by Na+ or a glutamate transporter driven by either Na+ or H+. Here we use purified protein reconstituted into liposomes to thoroughly characterize the ion and substrate dependence of the GltPh transport. We confirm that GltPh is a Na+-dependent transporter that is highly selective for aspartate over other amino acids, and we show that transport is coupled to at least two Na+ ions. In contrast to the EAATs, transport via GltPh is independent of H+ and K+. We propose a kinetic model of transport in which at least two Na+ ions are coupled to the cotransport of each aspartate molecule by GltPh, and where an ion- and substrate-free transporter reorients to complete the transport cycle. PMID:19380583

Ryan, Renae M; Compton, Emma L R; Mindell, Joseph A

2009-06-26

102

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

103

Topographic Maps III: Back Azimuths and Triangulation  

NSDL National Science Digital Library

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

104

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

E-print Network

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

Green, Paul Elijah

2006-01-01

105

Functional characterization of a Na+-dependent dicarboxylate transporter from Vibrio cholerae  

PubMed Central

The SLC13 transporter family, whose members play key physiological roles in the regulation of fatty acid synthesis, adiposity, insulin resistance, and other processes, catalyzes the transport of Krebs cycle intermediates and sulfate across the plasma membrane of mammalian cells. SLC13 transporters are part of the divalent anion:Na+ symporter (DASS) family that includes several well-characterized bacterial members. Despite sharing significant sequence similarity, the functional characteristics of DASS family members differ with regard to their substrate and coupling ion dependence. The publication of a high resolution structure of dimer VcINDY, a bacterial DASS family member, provides crucial structural insight into this transporter family. However, marrying this structural insight to the current functional understanding of this family also demands a comprehensive analysis of the transporter’s functional properties. To this end, we purified VcINDY, reconstituted it into liposomes, and determined its basic functional characteristics. Our data demonstrate that VcINDY is a high affinity, Na+-dependent transporter with a preference for C4- and C5-dicarboxylates. Transport of the model substrate, succinate, is highly pH dependent, consistent with VcINDY strongly preferring the substrate’s dianionic form. VcINDY transport is electrogenic with succinate coupled to the transport of three or more Na+ ions. In contrast to succinate, citrate, bound in the VcINDY crystal structure (in an inward-facing conformation), seems to interact only weakly with the transporter in vitro. These transport properties together provide a functional framework for future experimental and computational examinations of the VcINDY transport mechanism. PMID:24821967

Mulligan, Christopher; Fitzgerald, Gabriel A.; Wang, Da-Neng

2014-01-01

106

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

107

Time-dependent radiation transport using the staggered-block Jacobi method  

Microsoft Academic Search

The time-dependent radiation transport equation describes the dynamics of radiation traveling through and interacting with a background medium. These dynamics are important in a diversity of fields including nuclear reactor kinetics, stellar evolution, and inertial confinement fusion. Except for trivial problems, the transport equation must be solved numerically. This research is concerned with developing a new deterministic time discretization for

Gregory Grant Davidson

2010-01-01

108

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

E-print Network

Numerical Study of Electromagnetic ETG Turbulence: -dependence of Electron Heat Transport B. Labit. To this end, we have developed a 3D toroidal global fluid code that solves a non-linear electromagnetic model, that magnetic fluctuations play an important role in electron transport [1]. Electromagnetic effects

109

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

Microsoft Academic Search

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

A. Pautz

110

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

111

Comparative cation dependency of sugar transport by crustacean hepatopancreas and intestine.  

PubMed

Glucose is transported in crustacean hepatopancreas and intestine by Na(+)-dependent co-transport, while Na(+)-dependent D-fructose influx has only been described for the hepatopancreas. It is still unclear if the two sugars are independently transported by two distinct cation-dependent co-transporter carrier systems. In this study, lobster (Homarus americanus) hepatopancreas brush border membrane vesicles (BBMV) were used to characterize, in detail, the cation-dependency of both D-[(3)H]-glucose and D-[(3)H]-fructose influxes, while in vitro perfused intestines were employed to determine the nature of cation-dependent sugar transport across this organ. Over the sodium concentration range of 0-100?mM, both [(3)H]-glucose and [(3)H]-fructose influxes (0.1?mM; 1?min uptakes) by hepatopancreatic BBMV were hyperbolic functions of [Na(+)]. [(3)H]-glucose and [(3)H]-fructose influxes by hepatopancreatic BBMV over a potassium concentration range of 15-100?mM were hyperbolic functions of [K(+)]. Both sugars displayed significant (p<0.01) Na(+)/K(+)-dependent and cation-independent uptake processes. Transepithelial 25?µM [(3)H]-glucose and [(3)H]-fructose fluxes across lobster intestine over luminal sodium and potassium concentration ranges of 0-50?mM and 5-100?mM, respectively, were hyperbolic functions of luminal [Na(+)] and [K(+)]. As with hepatopancreatic sugar transport, transepithelial intestinal sugar transport exhibited both significant (p<0.01) Na(+)/K(+)-dependent and cation-independent processes. Results suggest that both D-glucose and D-fructose are transported by a single SGLT-type carrier in each organ with sodium being the "preferred", high affinity, cation for both sugars in the hepatopancreas, and potassium being the "preferred", high affinity, cation for both sugars in the intestine. PMID:24950971

Duka, Ada; Ahearn, Gregory A

2014-01-01

112

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

PubMed

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

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

2014-04-01

113

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

114

A molecular mechanism for aberrant CFTR-dependent HCO(3)(-) transport in cystic fibrosis.  

PubMed

Aberrant HCO(3)(-) transport is a hallmark of cystic fibrosis (CF) and is associated with aberrant Cl(-)-dependent HCO(3)(-) transport by the cystic fibrosis transmembrane conductance regulator (CFTR). We show here that HCO(3)(-) current by CFTR cannot account for CFTR-activated HCO(3)(-) transport and that CFTR does not activate AE1-AE4. In contrast, CFTR markedly activates Cl(-) and OH(-)/HCO(3)(-) 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(-)/HCO(3)(-) ratio > or =2. SLC26A6 activity is voltage regulated and occurred at HCO(3)(-)/Cl(-) > or =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 HCO(3)(-) transport (one SLC26 transporter-electrogenic transport; two SLC26 transporters with opposite stoichiometry in the same membrane domain-electroneutral transport), the CF-associated aberrant HCO(3)(-) 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

2002-11-01

115

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

116

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

117

Relative azimuth inversion by way of damped maximum correlation estimates  

USGS Publications Warehouse

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

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

2012-01-01

118

Asymmetric transport in the bouncer model: Mixed, time dependent, noncompact dynamics  

E-print Network

We consider time-dependence of dynamical transport, following a recent study of the stadium billiard in which classical transmission and reflection probabilities were shown to exhibit exponential or algebraic decay depending on the choice of the lead or "hole". The system considered here is much more general, having a generic mixed phase space structure, time-dependence of the dynamics, and Fermi acceleration (trajectories with unbounded velocity). We propose an efficient numerical scheme for this model, observe the asymmetric transport effect, and discuss observed stretched exponential decays.

Carl P. Dettmann; Edson D. Leonel

2010-10-11

119

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

SciTech Connect

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

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

2012-07-01

120

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

121

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

SciTech Connect

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

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

2012-08-20

122

The temperature dependence of maltose transport in ale and lager strains of brewer's yeast  

PubMed Central

Lager beers are traditionally made at lower temperatures (6–14 °C) than ales (15–25 °C). At low temperatures, lager strains (Saccharomyces pastorianus) ferment faster than ale strains (Saccharomyces cerevisiae). Two lager and two ale strains had similar maltose transport activities at 20 °C, but at 0 °C the lager strains had fivefold greater activity. AGT1, MTT1 and MALx1 are major maltose transporter genes. In nine tested lager strains, the AGT1 genes contained premature stop codons. None of five tested ale strains had this defect. All tested lager strains, but no ale strain, contained MTT1 genes. When functional AGT1 from an ale strain was expressed in a lager strain, the resultant maltose transport activity had the high temperature dependence characteristic of ale yeasts. Lager yeast MTT1 and MALx1 genes were expressed in a maltose-negative laboratory strain of S. cerevisiae. The resultant Mtt1 transport activity had low temperature dependence and the Malx1 activity had high temperature dependence. Faster fermentation at low temperature by lager strains than ale strains may result from their different maltose transporters. The loss of Agt1 transporters during the evolution of lager strains may have provided plasma membrane space for the Mtt1 transporters that perform better at a low temperature. PMID:20402791

Vidgren, Virve; Multanen, Jyri-Pekka; Ruohonen, Laura; Londesborough, John

2010-01-01

123

Spin-dependent transport between magnetic nanopillars through a nano-granular metal matrix  

NASA Astrophysics Data System (ADS)

We investigate the influence of local magnetic field on the spin-dependent transport properties of magnetic granular metals. By means of electron-beam-induced-deposition we fabricate a complex granular system made of Co nanopillars embedded in a Pt-C nano-granular metal matrix. We identify two different spin-dependent tunnelling regimes. In the first one, transport occurs almost exclusively through the nano-granular Pt-C matrix and it is affected by the local stray field due to the Co nanopillars. In the second regime, the transport takes place through both the Pt-C matrix and the Co nanopillars. These two transport regimes are discriminated by the different sign of the magnetoresistance. In particular, a strong enhancement of the magnetoresistance is found at low temperatures in the second regime, which is caused by spin-flip scattering and higher order tunnelling processes.

Porrati, F.; Begun, E.; Sachser, R.; Huth, M.

2014-11-01

124

Aglycone exploration of C-arylglucoside inhibitors of renal sodium-dependent glucose transporter SGLT2  

Microsoft Academic Search

Inhibition of sodium-dependent glucose transporter 2 (SGLT2), the transporter that is responsible for renal re-uptake of glucose, leads to glucosuria in animals. SGLT-mediated glucosuria provides a mechanism to shed excess plasma glucose to ameliorate diabetes-related hyperglycemia and associated complications. The current study demonstrates that the proper relationship of a 4?-substituted benzyl group to a ?-1C-phenylglucoside is important for potent and

Bruce A. Ellsworth; Wei Meng; Manorama Patel; Ravindar N. Girotra; Gang Wu; Philip M. Sher; Deborah L. Hagan; Mary T. Obermeier; William G. Humphreys; James G. Robertson; Aiying Wang; Songping Han; Thomas L. Waldron; Nathan N. Morgan; Jean M. Whaley; William N. Washburn

2008-01-01

125

Evidence for Nucleotide-Dependent Passive H+ Transport Protein in the Plasma Membrane of Barley Roots  

Microsoft Academic Search

; Plasma membranes were isolated from barley roots by two-phase partitioning, and octylglucoside-soluble and -insoluble fractions were obtained. The insoluble fractions were reconstituted into liposomes, and the plasma mem- brane H+-ATPase was shown to participate in MgATP- dependent H+ transport activity. The H+ transport was decreased when the octylglucoside-soluble fraction was reconstituted together with the insoluble fraction. The decrease was

Kousei Yamashita; Tetsuro Mimura; Ken-ichiro Shimazaki

2003-01-01

126

On perturbative azimuthal asymmetry at RHIC  

SciTech Connect

We investigate the azimuthal asymmetry of partons and photons produced at the initial stage of nuclear collisions at the RHIC energy originating from quark-nucleus collisions. In our approach, the azimuthal asymmetry results from the correlation between color dipole orientation and impact parameter of the collision. The asymmetry is sensitive to the rapid variation of the nuclear density at the nuclear periphery. We either introduce the color-dipole orientation into the improved Born approximation, or model the dipole partial amplitude which satisfies available DIS data. We conclude that the azimuthal asymmetry coming from these mechanisms can be sizable.

Rezaeian, A. H. [Departamento de Fisica y Centro de Estudios Subatomicos, Universidad Tecnica Federico Santa Maria, Casilla 110-V, Valparaiso (Chile)

2008-10-13

127

IMF control of the azimuthal direction of earthward magnetotail fast flows?  

NASA Astrophysics Data System (ADS)

Cluster magnetotail data together with ACE solar wind data from 2001-2009 are used to investigate the dependence of the azimuthal flow direction of earthward magnetotail fast flows on the interplanetary magnetic field (IMF). We find indication that fast flows have favorable azimuthal directions that are dependent on the IMF. Our results suggest that for positive IMF By the favorable azimuthal direction of the fast flows is dawnward in the northern plasma sheet and duskward in the southern plasma sheet. For negative IMF By an opposite situation takes place, the favorable azimuthal flow directions are then duskward and dawnward in the northern and southern plasma sheet, respectively. The results are in agreement with the idea that untwisting of reconnected magnetic field lines directs the fast flows in the magnetotail, the field line twist itself being controlled by the IMF.

Pitkänen, T.; Hamrin, M.; Norqvist, P.; Karlsson, T.; Nilsson, H.

2013-12-01

128

Field dependent and disorder-induced nonlinear charge transport in electrochemically doped polypyrrole devices  

NASA Astrophysics Data System (ADS)

Electric field activated charge transport is studied in the metal/polymer/metal device structure of electropolymerized polypyrrole down to 10?K with varying carrier density and disorder. Disorder induced nonlinear behaviour is observed in polypyrrole devices grown at room temperature which is correlated to delocalization of states. The slope parameter of current–voltage characteristics (in log–log scale) increases as the temperature decreases, which indicates the onset of stronger field dependence. The field dependence of mobility becomes dominant as the carrier density decreases. The sharp dip in differential conductance indicates the localization of carriers at low temperatures which reduces the effective number of carriers involved in the transport.

Anjaneyulu, P.; Varade, Vaibhav; Suchand Sangeeth, C. S.; Ramesh, K. P.; Menon, R.

2014-12-01

129

Spin-dependent quasiparticle transport in aluminum single-electron transistors.  

PubMed

We investigate the effect of Zeeman splitting on quasiparticle transport in normal-superconducting-normal (NSN) aluminum single-electron transistors (SETs). In the above-gap transport, the interplay of Coulomb blockade and Zeeman splitting leads to spin-dependence of the sequential tunneling. This creates regimes where either one or both spin species can tunnel onto or off the island. At lower biases, spin-dependence of the single quasiparticle state is studied, and operation of the device as a bipolar spin filter is suggested. PMID:17026322

Ferguson, A J; Andresen, S E; Brenner, R; Clark, R G

2006-08-25

130

Structure dependent energy transport: relaxation-assisted 2DIR measurements and theoretical studies.  

PubMed

Vibrational energy relaxation and transport in a molecule that is far from thermal equilibrium can affect its chemical reactivity. Understanding the energy transport dynamics in such molecules is also important for measuring molecular structural constraints via relaxation-assisted two-dimensional infrared (RA 2DIR) spectroscopy. In this paper we investigated vibrational relaxation and energy transport in the ortho, meta, and para isomers of acetylbenzonitrile (AcPhCN) originated from excitation of the CN stretching mode. The amplitude of the cross-peak among the CN and CO stretching modes served as an indicator for the energy transport from the CN group toward the CO group. A surprisingly large difference is observed in both the lifetimes of the CN mode and in the energy transport rates for the three isomers. The anharmonic DFT calculations and energy transport modeling performed to understand the origin of the differences and to identify the main cross-peak contributors in these isomers described well the majority of the experimental results including mode excited-state lifetimes and the energy transport dynamics. The strong dependence of the energy transport on molecular structure found in this work could be useful for recognizing different isomers of various compounds via RA 2DIR spectroscopy. PMID:21859144

Kasyanenko, Valeriy M; Tesar, Sarah L; Rubtsov, Grigory I; Burin, Alexander L; Rubtsov, Igor V

2011-09-29

131

Probing TMDs through azimuthal distributions of pions inside a jet in hadronic collisions  

NASA Astrophysics Data System (ADS)

The azimuthal distributions around the jet axis of leading pions produced in the jet fragmentation process in pp collisions are studied within the framework of the so-called generalized parton model. The observable leading-twist azimuthal asymmetries are estimated in kinematic configurations presently investigated at RHIC. It is shown how the main contributions coming from the Collins and Sivers effects can be disentangled. In addition, a test of the process dependence of the Sivers function is provided.

D'Alesio, U.; Murgia, F.; Pisano, C.

2014-01-01

132

Dynamic potential-dependent electron transport pathway shifts in anode biofilms of Geobacter sulfurreducens.  

PubMed

Biofilms of the anode-respiring bacterium Geobacter sulfurreducens (G. sulfurreducens) demonstrate dynamic potential-dependent changes between two electron transport pathways that are used selectively depending on the anode potential. Electrochemical impedance spectroscopy (EIS) measurements suggest that these pathways (both n=1), with midpoint potentials of -0.155 (± 0.005) and -0.095 (± 0.003) V versus standard hydrogen electrode, are not additive within the biofilm, but are preferentially used depending on the anode potential. Potential step voltammetry and cyclic voltammetry (CV) confirmed rapid changes between the two pathways in minutes when the anode potential is changed. We confirm that the electrochemical response observed in a slow-scan-rate CV (?1?mV?s(-1) ) is often composed of at least the two pathways characterized. Thus, beyond understanding the electron transport pathways in G.?sulfurreducens, this study also has implications on the interpretation of previously collected and future potential-dependent datasets. PMID:25351488

Yoho, Rachel A; Popat, Sudeep C; Torres, César I

2014-12-01

133

Azimuthal harmonics of color fields in a high energy nucleus  

E-print Network

Recent experimental results have revealed a surprisingly rich structure of multiparticle azimuthal correlations in high energy proton-nucleus collisions. Final state collective effects can be responsible for many of the observed effects, but it has recently been argued that a part of these correlations are present already in the wavefunctions of the colliding particles. We evaluate the momentum space 2-particle cumulant azimuthal anisotropy coefficients v_n{2}, n=2,3,4 from fundamental representation Wilson line distributions describing the high energy nucleus. These would correspond to the flow coefficients in very forward proton nucleus scattering. We find significant differences beteen Wilson lines from the MV model and from JIMWLK evolution. The magnitude and transverse momentum dependence of the v_n{2} values suggest that the fluctuations present in the initial fields are a significant contribution to the observed anisotropies.

Lappi, T

2015-01-01

134

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

135

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

Microsoft Academic Search

We report experimental measurements of the salt dependence of ion transport and DNA translocation through solid-state nanopores. The ionic conductance shows a three-order-of-magnitude decrease with decreasing salt concentrations fro m1Mt o 1ÌM, strongly deviating from bulk linear behavior. The data are described by a model that accounts for a salt-dependent surface charge of the pore. Subsequently, we measure translocation of

Ralph M. M. Smeets; Ulrich F. Keyser; Diego Krapf; Meng-Yue Wu; Nynke H. Dekker; Cees Dekker

2006-01-01

136

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

Microsoft Academic Search

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

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

2000-01-01

137

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

138

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

E-print Network

. The code had the capability of calculating the tritium release and inventory in tran- sient as wellModeling and analysis of time-dependent tritium transport in lithium oxide A. Badawi, A.R. Raray the tritium release and inventory in the blanket. A model has been developed at UCLA to describe the tritium

Raffray, A. René

139

Fabrication and electric-field-dependent transport measurements of mesoscopic graphite devices  

E-print Network

Fabrication and electric-field-dependent transport measurements of mesoscopic graphite devices micromechanical method to extract extremely thin graphite samples. Graphite crystallites with thicknesses ranging from 10 to 100 nm and lateral size 2 m are extracted from bulk. Mesoscopic graphite devices

Cobden, David

140

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.

141

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

142

CONDENSED MATTER: ELECTRONICSTRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICALPROPERTIES: Time-Dependent Transport in Nanoscale Devices  

NASA Astrophysics Data System (ADS)

A method for simulating ballistic time-dependent device transport, which solves the time-dependent Schrödinger equation using the finite difference time domain (FDTD) method together with Poisson's equation, is described in detail. The effective mass Schrödinger equation is solved. The continuous energy spectrum of the system is discretized using adaptive mesh, resulting in energy levels that sample the density-of-states. By calculating time evolution of wavefunctions at sampled energies, time-dependent transport characteristics such as current and charge density distributions are obtained. Simulation results in a nanowire and a coaxially gated carbon nanotube field-effect transistor (CNTFET) are presented. Transient effects, e.g., finite rising time, are investigated in these devices.

Chen, Zhi-Dong; Zhang, Jin-Yu; Yu, Zhi-Ping

2009-03-01

143

K+-dependent Na+ transport driven by respiration in Escherichia coli cells and membrane vesicles.  

PubMed

Respiration-driven Na+ transport from Escherichia coli cells and right-side-out membrane vesicles is strictly dependent on K+. Cells from an E. colic mutant deficient in three major K+ transport systems were incapable of accumulating K+ or expelling Na+ unless valinomycin was added. Membrane vesicles from an E. coli mutant from which the genes encoding the two known electrogenic Na+/nH+ antiporters nhaA and nhaB were deleted transported Na+ as well as did vesicles from wild-type cells. Quantitative analysis of Delta psi and Delta pH showed a high driving force for electrogenic Na+/nH+ antiport whether K+ was present or not, although Na+ transport occurred only in its presence. These results suggest that an Na+/nH+ antiporter is not responsible for the Na+ transport. Respiration-driven efflux of Na+ from vesicles was found to be accompanied by primary uphill efflux of K+. Also, no respiration-dependent efflux of K+ was observed in the absence of Na+. Such coupling between Na+ and K+ fluxes may be explained by the operation of an Na+, K+/H+ antiporter previously described in E. coli membrane vesicles (Verkhovskay, M.L., Verkhovsky, M.I. and Wikström, M. (1995) FEBS Lett. 363, 46-48). Active Na+ transport is abolished when delta mu H+ is eliminated by a protonophore, but at low concentrations the protonophore actually accelerated Na+ transport. Such an effect may be expected if the Na+, K+/H+ antiporter normally operates in tight conjunction with respiratory chain complexes, thus exhibiting some phenomenological properties of a primary redox-linked sodium pump. PMID:8616158

Verkhovskaya, M L; Verkhovsky, M I; Wikström, M

1996-03-28

144

Allelic variation in serotonin transporter function associated with the intensity dependence of the auditory evoked potential.  

PubMed

The intensity dependence of the auditory evoked potential (AEP) has been suggested as an indicator of central serotonergic function, a strong intensity dependence presumably reflecting low serotonergic activity. As individual differences in serotonergic neurotransmission can be accounted for in part by genetic variation in genes of the serotonergic pathway, we investigated whether a functional polymorphism in the promoter region of the serotonin transporter gene (5-HTTLPR) is associated with the AEP intensity dependence. Because dopaminergic influences on the intensity dependence have also been reported, we furthermore explored the role of a functional polymorphism in the dopamine D4 receptor gene (DRD4 exon III) in the modulation of the AEP intensity dependence. AEPs to tones of six intensity levels were recorded from 60 healthy young individuals, and N1/P2 linear as well as median slopes at central electrode sites were computed as measures of the AEP intensity dependence. Analyses of variance showed that there was a significant effect of the 5-HTTLPR on the AEP intensity dependence. Individuals with the ll genotype exhibited a stronger intensity dependence compared to individuals with the ls genotype. This effect was even more pronounced when DRD4 exon III was considered in the analyses. In conclusion, these findings provide further evidence for a role of serotonergic neurotransmission in the modulation of the AEP intensity dependence. The results also point to possible dopaminergic influences on the AEP intensity dependence. PMID:12627465

Strobel, A; Debener, S; Schmidt, D; Hünnerkopf, R; Lesch, K-P; Brocke, B

2003-04-01

145

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

SciTech Connect

The results on time-dependent 2-D fluid modeling of edge plasmas with non-diffusive intermittent transport across the magnetic field (termed cross-field) based on the novel macro-blob approach are presented. The capability of this approach to simulate the long temporal evolution ({approx}0.1 s) of the background plasma and simultaneously the fast spatiotemporal dynamics of blobs ({approx}10{sup -4} s) is demonstrated. An analysis of a periodic sequence of many macro-blobs (PSMB) is given showing that the resulting plasma attains a dynamic equilibrium. Plasma properties in the dynamic equilibrium are discussed. In PSMB modeling, the effect of macro-blob generation frequency on edge plasma parameters is studied. Comparison between PSMB modeling and experimental profile data is given. The calculations are performed for the same plasma discharge using two different models for anomalous cross-field transport: time-average convection and PSMB. Parametric analysis of edge plasma variation with transport coefficients in these models is presented. The capability of the models to accurately simulate enhanced transport due to blobs is compared. Impurity dynamics in edge plasma with macro-blobs is also studied showing strong impact of macro-blob on profiles of impurity charge states caused by enhanced outward transport of high-charge states and simultaneous inward transport of low-charge states towards the core. Macro-blobs cause enhancement of sputtering rates, increase radiation and impurity concentration in plasma, and change erosion/deposition patterns.

Pigarov, A. Yu.; Krasheninnikov, S. I. [University of California at San Diego, La Jolla, California 92093 (United States); Rognlien, T. D. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States)

2012-07-15

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

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

NASA Astrophysics Data System (ADS)

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

Li, Tao; Mallick, Subhashis

2015-02-01

148

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

E-print Network

to transform the infinite dimensional system into a set of finite dimensional Ordinary Differential Equations dependent Riccati equation, Galerkin's method. I. INTRODUCTION Cable transporter systems are widely usedOptimal Control using State Dependent Riccati Equation (SDRE) for a Flexible Cable Transporter

Pota, Himanshu Roy

149

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

150

Role of cyclic-AMP-dependent protein kinase in catabolite inactivation of the glucose and galactose transporters in Saccharomyces cerevisiae.  

PubMed

The derepressed high-affinity glucose transport system and the induced galactose transport system are catabolite inactivated when cells with these transport systems are incubated with glucose. The role of the cyclic AMP cascade in the catabolite inactivation of these transport systems was shown by using mutants affected in the activity of cyclic-AMP-dependent protein kinase (cAPK). In tpk1(w) mutants with reduced cAPK activity, the sugar transport systems were expressed but were not catabolite inactivated. In bcy1 mutants with unbridled cAPK activity resulting from a defective regulatory subunit, the transport systems were absent or present at low levels. PMID:2542229

Ramos, J; Cirillo, V P

1989-06-01

151

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

152

Examination of temperature dependent subgroup formulations in direct whole core transport calculation for power reactors  

SciTech Connect

The traditional subgroup method which has been applied for lattice transport calculations has an inherent limitation for non-uniform temperature distributions. As a measure to incorporate temperature dependence into the subgroup formulation, the subgroup level and number density adjustment method have been proposed. In this paper, the temperature dependent subgroup formulations employed for reflecting the non-uniform temperature effects on the resonance spatial self-shielding are examined for the whole core transport calculation with the thermal feedback. For 2D pin-cell problem with non-uniform temperature profiles, the inherent limitation of conventional subgroup method is confirmed. And the improvement in terms of reactivity is observed with the proposed adjustment scheme. For the real PWR core calculation with thermal feedback in the hot-full-power condition, the noticeable correction for the fuel temperature coefficient by about 10% more negative is obtained with the correction schemes. (authors)

Jung, Y. S.; Lee, U. C.; Joo, H. G. [Dept. of Nuclear Engineering, Seoul National Univ., 599 Gwanak-ro, Gwanak-gu, Seoul (Korea, Republic of)

2012-07-01

153

Orbital-cooperative spin fluctuation and orbital-dependent transport in ruthenates  

NASA Astrophysics Data System (ADS)

Unusual transport properties deviating from the Fermi liquid are observed in ruthenates near a magnetic quantum-critical point (QCP). To understand the electronic properties of the ruthenates near and away from an antiferromagnetic (AF) QCP, I study the electronic structure and magnetic and transport properties for the t2 g-orbital Hubbard model on a square lattice in fluctuation-exchange approximation including Maki-Thompson (MT) current vertex correction (CVC). The results away from the AF QCP reproduce several experimental results of Sr2RuO4 qualitatively and provide new mechanisms about the enhancement of spin fluctuation at QIC -AF?(0.66 ? ,0.66 ? ) , larger mass enhancement of the dx y orbital than that of the dx z /y z orbital, and nonmonotonic temperature dependence of the Hall coefficient. Also, the results near the AF QCP explain the T -linear inplane resistivity in Sr2Ru0.075Ti0.025O4 and give an experimental test on the obtained temperature dependence of the Hall coefficient. I reveal spatial correlation including the self-energy of electrons beyond mean-field approximations is essential to determine the electronic properties of the ruthenates. I also show several ubiquitous transport properties near an AF QCP and characteristic transport properties of a multiorbital system by comparison with results of a single-orbital system near an AF QCP.

Arakawa, Naoya

2014-12-01

154

Structure and mechanism of a bacterial sodium-dependent dicarboxylate transporter  

PubMed Central

In human cells, cytosolic citrate is a major precursor for the synthesis of fatty acids, triacylglycerols, cholesterol and low-density lipoprotein. Cytosolic citrate further regulates the cell’s energy balance by activating the fatty acid synthesis pathway while down-regulating both the glycolysis and fatty acid ?-oxidation pathways (Supplementary Fig. 1) 1–4. The rate of fatty acid synthesis in liver and adipose cells, the two major tissue types for such synthesis, correlates directly with the concentration of citrate in the cytosol 2–5. The cytosolic citrate concentration partially depends on direct import across the plasma membrane via the Na+-dependent citrate transporter (NaCT) 6,7. Mutations of the homologous fly gene (INDY, I’m Not Dead Yet) result in reduced fat storage through calorie restriction 8. More recently, NaCT-knockout mice have been found to have increased hepatic mitochondrial biogenesis, higher lipid oxidation and energy expenditure, and reduced lipogenesis, which taken together protect the mice from obesity and insulin resistance 9. To understand the transport mechanism of NaCT/INDY proteins, here we report the 3.2 Å crystal structure of a bacterial INDY homolog. One citrate molecule and one sodium ion are bound per protein, and their binding sites are defined by conserved amino acid motifs, forming the structural basis for understanding the transporters’ specificity. Comparison of the structures of the two symmetrical halves of the transporter suggests conformational changes that propel substrate translocation. PMID:23086149

Mancusso, Romina; Gregorio, G. Glenn; Liu, Qun; Wang, Da-Neng

2013-01-01

155

[Age-dependent changes in mRNA transport (nucleus-cytoplasm)].  

PubMed

Transport of mRNA from nucleus to cytoplasm is an ATP-dependent process which occurs strictly vectorially. Because the mRNA is structurally bound during transport, mRNA transport is a "solid-state" process consisting of i) mRNA release from the nuclear matrix, ii) mRNA translocation through the nuclear pore, and iii) cytoskeletal binding. We identified and purified the following components involved in the translocation step: i) the nuclear envelope (NE) nucleoside triphosphatase (NTPase) which is stimulated by the 3'poly(A) tail of mRNA, ii) the poly(A)-recognizing mRNA carrier, iii) the NE protein kinase, and iv) the NE phosphatase. In addition, we found that an RNA helicase activity is present in NE, which also may be involved in RNA transport. Our results show that, besides poly(A), also double-stranded RNA structures may modulate RNA export. The amount of mRNA released from nuclei markedly decreases with age. Evidence is presented that this age-dependent change is caused by an impairment of polyadenylation of mRNA, hnRNA processing, release of mRNA from nuclear matrix, and translocations of mRNA from nuclear to cytoplasmic compartment (decrease in activities of NE NTPase, protein kinase, and phosphatase; decrease in poly(A)-binding affinity of mRNA carrier). PMID:8212790

Müller, W E; Agutter, P S; Prochnow, D J; Fasold, H; Sève, A P; Tsiapalis, C M; Schröder, H C

1993-01-01

156

Green's function of the time-dependent radiative transport equation in terms of rotated spherical harmonics  

NASA Astrophysics Data System (ADS)

The time-dependent radiative transport equation is solved for the three-dimensional spatially uniform infinite medium which is illuminated by a point unidirectional source using a spherical harmonics transform under rotation. Apart from the numerical evaluation of a spherical Hankel transform which connects the spatial distance with the radial distance in Fourier space, the dependence on all variables is found analytically. For the special case of a harmonically modulated source, even the spherical Hankel transform can be carried out analytically. Additionally, a special solution for the isotropically scattering infinite medium is given. The Monte Carlo method is used for a successful verification of the derived solution.

Liemert, André; Kienle, Alwin

2012-09-01

157

Green's function of the time-dependent radiative transport equation in terms of rotated spherical harmonics.  

PubMed

The time-dependent radiative transport equation is solved for the three-dimensional spatially uniform infinite medium which is illuminated by a point unidirectional source using a spherical harmonics transform under rotation. Apart from the numerical evaluation of a spherical Hankel transform which connects the spatial distance with the radial distance in Fourier space, the dependence on all variables is found analytically. For the special case of a harmonically modulated source, even the spherical Hankel transform can be carried out analytically. Additionally, a special solution for the isotropically scattering infinite medium is given. The Monte Carlo method is used for a successful verification of the derived solution. PMID:23031041

Liemert, André; Kienle, Alwin

2012-09-01

158

Temperature dependent spin transport properties of platinum inferred from spin Hall magnetoresistance measurements  

NASA Astrophysics Data System (ADS)

We study the temperature dependence of the spin Hall magnetoresistance (SMR) in yttrium iron garnet/platinum hybrid structures via magnetization orientation dependent magnetoresistance measurements. Our experiments show a decrease of the SMR magnitude with decreasing temperature. Using the sensitivity of the SMR to the spin transport properties of the normal metal, we interpret our data in terms of a decrease of the spin Hall angle in platinum from 0.11 at room temperature to 0.075 at 10 K, while the spin diffusion length and the spin mixing conductance of the ferrimagnetic insulator/normal metal interface remain almost constant.

Meyer, Sibylle; Althammer, Matthias; Geprägs, Stephan; Opel, Matthias; Gross, Rudolf; Goennenwein, Sebastian T. B.

2014-06-01

159

Temperature dependent spin transport properties of platinum inferred from spin Hall magnetoresistance measurements  

SciTech Connect

We study the temperature dependence of the spin Hall magnetoresistance (SMR) in yttrium iron garnet/platinum hybrid structures via magnetization orientation dependent magnetoresistance measurements. Our experiments show a decrease of the SMR magnitude with decreasing temperature. Using the sensitivity of the SMR to the spin transport properties of the normal metal, we interpret our data in terms of a decrease of the spin Hall angle in platinum from 0.11 at room temperature to 0.075 at 10?K, while the spin diffusion length and the spin mixing conductance of the ferrimagnetic insulator/normal metal interface remain almost constant.

Meyer, Sibylle, E-mail: sibylle.meyer@wmi.badw-muenchen.de; Althammer, Matthias; Geprägs, Stephan; Opel, Matthias; Goennenwein, Sebastian T. B. [Walther-Meißner-Institut, Bayerische Akademie der Wissenschaften, 85748 Garching (Germany); Gross, Rudolf [Walther-Meißner-Institut, Bayerische Akademie der Wissenschaften, 85748 Garching (Germany); Physik-Department, Technische Universität München, 85748 Garching (Germany)

2014-06-16

160

Evidence of sodium-dependent glucose transport in human erythroleukemia cells  

Microsoft Academic Search

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

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

1996-01-01

161

Time Dependent Simulation of Relativistic Electron Transport and Synchrotron Emission in Radio Galaxies  

Microsoft Academic Search

We present first results from simulations of relativistic electron transport and shock acceleration in time-dependent, multi-dimensional, magnetohydrodynamic, jet flows. These preliminary calculations are based on light, axis-symmetric jets carrying helical magnetic fields. The simulations are done using a new scheme designed for the moderate electron energies associated with radio synchrotron emission in radio galaxies. This enables us to follow the

T. W. Jones; D. Ryu; A. Engel

1998-01-01

162

Azimuthal anisotropy measurements by STAR  

NASA Astrophysics Data System (ADS)

The recent study of centrality and transverse momentum (pT) dependence of inclusive charged hardron elliptic anisotropy (v2) at midrapidity (|?|<1.0) in Au+Au collision at ?{sNN}=7.7,11.5,19.6,27, and 39 GeV in STAR Beam Energy Scan program is presented. We show that the observed increase of inclusive v2 is mainly due to the average pT increase with energy. In Au+Au 200 GeV collisions, the triangular anisotropy (v3) measurements highly depend on measurement methods; v3 is strongly dependent on ??. The difference between two- and four-particle cumulants v2{2} and v2{4} for Au+Au and Cu+Cu collision at ?{sNN}=62.4 and 200 GeV is used to explore flow fluctuations. Furthermore, by exploiting the symmetry of average flow in pseudorapidity ? about midrapidity, the ??-dependent and independent components are separated using v2{2} and v2{4}.

Yi, Li

2014-06-01

163

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

164

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

NASA Astrophysics Data System (ADS)

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

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

1997-05-01

165

Chronic and acute regulation of Na+/Cl- -dependent neurotransmitter transporters: drugs, substrates, presynaptic receptors, and signaling systems.  

PubMed

Na+/Cl- -dependent neurotransmitter transporters, which constitute a gene superfamily, are crucial for limiting neurotransmitter activity. Thus, it is critical to understand their regulation. This review focuses primarily on the norepinephrine transporter, the dopamine transporter, the serotonin transporter, and the gamma-aminobutyric acid transporter GAT1. Chronic administration of drugs that alter neurotransmitter release or inhibit transporter activity can produce persistent compensatory changes in brain transporter number and activity. However, regulation has not been universally observed. Transient alterations in norepinephrine transporter, dopamine transporter, serotonin transporter, and GAT1 function and/or number occur in response to more acute manipulations, including membrane potential changes, substrate exposure, ethanol exposure, and presynaptic receptor activation/inhibition. In many cases, acute regulation has been shown to result from a rapid redistribution of the transporter between the cell surface and intracellular sites. Second messenger systems involved in this rapid regulation include protein kinases and phosphatases, of which protein kinase C has been the best characterized. These signaling systems share the common characteristic of altering maximal transport velocity and/or cell surface expression, consistent with regulation of transporter trafficking. Although less well characterized, arachidonic acid, reactive oxygen species, and nitric oxide also alter transporter function. In addition to post-translational modifications, cytoskeleton interactions and transporter oligomerization regulate transporter activity and trafficking. Furthermore, promoter regions involved in transporter transcriptional regulation have begun to be identified. Together, these findings suggest that Na+/Cl- -dependent neurotransmitter transporters are regulated both long-term and in a more dynamic manner, thereby providing several distinct mechanisms for altering synaptic neurotransmitter concentrations and neurotransmission. PMID:11750035

Zahniser, N R; Doolen, S

2001-10-01

166

Two-particle azimuthal correlations at forward rapidity in STAR  

NASA Astrophysics Data System (ADS)

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

Braidot, E.

2011-01-01

167

ATP-dependent calcium transport in rat parotid basolateral membrane vesicles is modulated by membrane potential.  

PubMed

The ATP-dependent Ca2+ transport activity (T. Takuma, B.L. Kuyatt and B.J. Baum, Biochem. J. 227:239-245, 1985) exhibited by inverted basolateral membrane vesicles isolated from rat parotid gland was further characterized. The activity was dependent on Mg2+. Phosphate (5 mM), but not oxalate (5 mM), increased maximum Ca2+ accumulation by 50%. Half-maximal Ca2+ transport was achieved at approximately 70 nM Ca2+ in EGTA-buffered medium while maximal activity required greater than 1 microM Ca2+ (Vmax = 54 nmol/mg protein/min). Optimal rates of Ca2+ transport were obtained in the presence of KCl, while in a KCl-free medium (mannitol or sucrose) approximately 40% of the total activity was achieved, which could not be stimulated by FCCP. The initial rate of Ca2+ transport could be significantly altered by preimposed membrane potentials generated by K+ gradients in the presence of valinomycin. Compared to the transport rate in the absence of membrane potential, a negative (interior) potential stimulated uptake by approximately 30%, while a positive (interior) potential inhibited uptake. Initial rates of Ca2+ uptake could also be altered by imposing pH gradients, in the absence of KCl. When compared to the initial rate of Ca2+ transport in the absence of a pH gradient, pHi = 7.5/pHo = 7.5; the activity was approximately 60% higher in the presence of an outwardly directed pH gradient, pHi = 7.5/pHo = 8.5; while it was approximately 80% lower when an inwardly directed pH gradient was imposed, pHi = 7.5/pHo = 6.2. The data show that the ATP-dependent Ca2+ transport in BLMV can be modulated by the membrane potential, suggesting therefore that there is a transfer of charge into the vesicle during Ca2+ uptake, which could be compensated by other ion movements. PMID:2969416

Ambudkar, I S; Baum, B J

1988-04-01

168

Scale-Dependent Fracture-Matrix Interactions And Their Impact on Radionuclide Transport - Final Report  

SciTech Connect

Matrix diffusion and adsorption within a rock matrix are widely regarded as important mechanisms for retarding the transport of radionuclides and other solutes in fractured rock (e.g., Neretnieks, 1980; Tang et al., 1981; Maloszewski and Zuber, 1985; Novakowski and Lapcevic, 1994; Jardine et al., 1999; Zhou and Xie, 2003; Reimus et al., 2003a,b). When remediation options are being evaluated for old sources of contamination, where a large fraction of contaminants reside within the rock matrix, slow diffusion out of the matrix greatly increases the difficulty and timeframe of remediation. Estimating the rates of solute exchange between fractures and the adjacent rock matrix is a critical factor in quantifying immobilization and/or remobilization of DOE-relevant contaminants within the subsurface. In principle, the most rigorous approach to modeling solute transport with fracture-matrix interaction would be based on local-scale coupled advection-diffusion/dispersion equations for the rock matrix and in discrete fractures that comprise the fracture network (Discrete Fracture Network and Matrix approach, hereinafter referred to as DFNM approach), fully resolving aperture variability in fractures and matrix property heterogeneity. However, such approaches are computationally demanding, and thus, many predictive models rely upon simplified models. These models typically idealize fracture rock masses as a single fracture or system of parallel fractures interacting with slabs of porous matrix or as a mobile-immobile or multi-rate mass transfer system. These idealizations provide tractable approaches for interpreting tracer tests and predicting contaminant mobility, but rely upon a fitted effective matrix diffusivity or mass-transfer coefficients. However, because these fitted parameters are based upon simplified conceptual models, their effectiveness at predicting long-term transport processes remains uncertain. Evidence of scale dependence of effective matrix diffusion coefficients obtained from tracer tests highlights this point and suggests that the underlying mechanisms and relationship between rock and fracture properties are not fully understood in large complex fracture networks. In this project, we developed a high-resolution DFN model of solute transport in fracture networks to explore and quantify the mechanisms that control transport in complex fracture networks and how these may give rise to observed scale-dependent matrix diffusion coefficients. Results demonstrate that small scale heterogeneity in the flow field caused by local aperture variability within individual fractures can lead to long-tailed breakthrough curves indicative of matrix diffusion, even in the absence of interactions with the fracture matrix. Furthermore, the temporal and spatial scale dependence of these processes highlights the inability of short-term tracer tests to estimate transport parameters that will control long-term fate and transport of contaminants in fractured aquifers.

Detwiler, Russell

2014-06-30

169

Capsaicinoids regulate airway anion transporters through Rho kinase- and cyclic AMP-dependent mechanisms.  

PubMed

To investigate the effects of capsaicinoids on airway anion transporters, we recorded and analyzed transepithelial currents in human airway epithelial Calu-3 cells. Application of capsaicin (100 ?M) attenuated vectorial anion transport, estimated as short-circuit currents (I(SC)), before and after stimulation by forskolin (10 ?M) with concomitant reduction of cytosolic cyclic AMP (cAMP) levels. The capsaicin-induced inhibition of I(SC) was also observed in the response to 8-bromo-cAMP (1 mM, a cell-permeable cAMP analog) and 3-isobutyl-1-methylxanthine (1 mM, an inhibitor of phosphodiesterases). The capsaicin-induced inhibition of I(SC) was attributed to suppression of bumetanide (an inhibitor of the basolateral Na(+)-K(+)-2 Cl(-) cotransporter 1)- and 4,4'-dinitrostilbene-2,2'-disulfonic acid (an inhibitor of basolateral HCO(3)(-)-dependent anion transporters)-sensitive components, which reflect anion uptake via basolateral cAMP-dependent anion transporters. In contrast, capsaicin potentiated apical Cl(-) conductance, which reflects conductivity through the cystic fibrosis transmembrane conductance regulator, a cAMP-regulated Cl(-) channel. All these paradoxical effects of capsaicin were mimicked by capsazepine. Forskolin application also increased phosphorylated myosin phosphatase target subunit 1, and the phosphorylation was prevented by capsaicin and capsazepine, suggesting that these capsaicinoids assume aspects of Rho kinase inhibitors. We also found that the increments in apical Cl(-) conductance were caused by conventional Rho kinase inhibitors, Y-27632 (20 ?M) and HA-1077 (20 ?M), with selective inhibition of basolateral Na(+)-K(+)-2 Cl(-) cotransporter 1. Collectively, capsaicinoids inhibit cAMP-mediated anion transport through down-regulation of basolateral anion uptake, paradoxically accompanied by up-regulation of apical cystic fibrosis transmembrane conductance regulator-mediated anion conductance. The latter is mediated by inhibition of Rho-kinase, which is believed to interact with actin cytoskeleton. PMID:21474433

Hibino, Yoshitaka; Morise, Masahiro; Ito, Yasushi; Mizutani, Takefumi; Matsuno, Tadakatsu; Ito, Satoru; Hashimoto, Naozumi; Sato, Mitsuo; Kondo, Masashi; Imaizumi, Kazuyoshi; Hasegawa, Yoshinori

2011-10-01

170

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

PubMed Central

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

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

2013-01-01

171

The Molecular Mechanism of Ion-Dependent Gating in Secondary Transporters  

PubMed Central

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.

2013-01-01

172

Potential-dependent anion transport across tonoplast vesicles from oat roots  

SciTech Connect

Potential-dependent anion movement was monitored as dissipation of membrane potentials using the fluorescence probe Oxonol V. The potentials (positive inside) were generated with the H/sup +/-pumping pyrophosphatase (PPase) associated with tonoplast vesicles. Unlike the H/sup +/-ATPase, the PPase is stimulated by K/sup +/ and insensitive to anions. The order of permeability for the anions tested was: SCN/sup -/ > Cl/sup -/ = NO/sub 3//sup -/ > Br/sup -/ >> SO/sub 4//sup =/ = H/sub 2/PO/sub 4//sup -/ > acetate = malate > iminodiacetate. Kinetic studies showed that the Cl/sup -/ and NO/sub 3//sup -/ transport activities are saturable (Km = 2 and 5 mM), indicating the existence of proteinaceous anion channels. In contrast to the H/sup +//Cl/sup -/ symporter identified in the same vesicles, the potential-dependent Cl/sup -/ transport was insensitive to 4,4'-diisothiocyano-2,2'-stilbene disulfonic acid. These results suggest the existence of at least two different mechanisms for Cl/sup -/ transport in these vesicles. The potentials generated by the H/sup +/-ATPase and the H/sup +/-PPase were non-additive, giving further support to the notion that both enzymes are on the same population of vesicles.

Kaestner, K.H.; Sze, H.

1986-04-01

173

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

SciTech Connect

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

Casalderrey-Solana, Jorge; Wang, Xin-Nian

2007-06-24

174

SURFACE CHARGE- AND SPACE-DEPENDENT TRANSPORT OF PROTEINS IN CROWDED ENVIRONMENTS OF NANOTAILORED POSTS  

PubMed Central

The reaction and diffusion of molecules across barriers and through crowded environments is integral to biological system function and to separation technologies. Ordered, microfabricated post arrays are a promising route to creating synthetic barriers with controlled chemical and physical characteristics. They can be used to create crowded environments, to mimic aspects of cellular membranes and to serve as engineered replacements of polymer-based separation media. Here, the translational diffusion of fluorescein isothiocyante and various forms of green fluorescent protein (GFP), including “supercharged” variants, are examined in a silicon-based post array environment. The technique of fluorescence recovery after photo-bleaching (FRAP) is combined with analytical approximations and numerical simulations to assess the relative effects of reaction and diffusion on molecular transport, respectively. FRAP experiments were conducted for 64 different cases where the molecular species, the spacing and density of the posts, and the chemical surface charge of the posts were varied. In all cases, the dense packing of the posts hindered the diffusive transport of the fluorescent species. The supercharged GFPs strongly interacted with oppositely charged surfaces. With similar molecular and surface charges, transport is primarily limited by hindered diffusion. For conventional, enhanced GFP in a positively charged surface environment, transport was limited by the coupled action of hindered diffusion and surface interaction with the posts. Quantification of the size-, space-, time-, and charge-dependent translational diffusion in the post array environments can provide insight into natural processes and guide the design and development of selective membrane systems. PMID:20515056

Choi, Chang Kyoung; Fowlkes, Jason D.; Retterer, Scott T.; Siuti, Piro; Iyer, Sukanya; Doktycz, Mitchel J.

2010-01-01

175

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

E-print Network

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

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

2014-01-01

176

Azimuthal emission patterns of K+ and of K- mesons in Ni + Ni collisions near the strangeness production threshold  

NASA Astrophysics Data System (ADS)

Azimuthal emission patterns of K± mesons have been measured in Ni + Ni collisions with the FOPI spectrometer at a beam kinetic energy of 1.91 A GeV. The transverse momentum pT integrated directed and elliptic flow of K+ and K- mesons as well as the centrality dependence of pT - differential directed flow of K+ mesons are compared to the predictions of hadron string dynamics and isospin quantum molecular dynamics transport models. The data exhibits different propagation patterns of K+ and K- mesons in the compressed and heated nuclear medium and favor the existence of a kaon-nucleon in-medium potential, repulsive for K+ mesons and attractive for K- mesons.

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

2014-08-01

177

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

E-print Network

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

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

2014-03-06

178

Effects of charge-dependent vibrational frequencies and anharmonicities in transport through Jens Koch and Felix von Oppen  

E-print Network

Effects of charge-dependent vibrational frequencies and anharmonicities in transport through-molecule devices, we investigate the effects of charge-dependent vibrational frequencies and anharmonic potentials into a multitude of substeps. This effectively leads to a bias-dependent broadening of vibrational features

von Oppen, Felix

179

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

180

Eigen decomposition solution to the one-dimensional time-dependent photon transport equation.  

PubMed

The time-dependent one-dimensional photon transport (radiative transfer) equation is widely used to model light propagation through turbid media with a slab geometry, in a vast number of disciplines. Several numerical and semi-analytical techniques are available to accurately solve this equation. In this work we propose a novel efficient solution technique based on eigen decomposition of the vectorized version of the photon transport equation. Using clever transformations, the four variable integro-differential equation is reduced to a set of first order ordinary differential equations using a combination of a spectral method and the discrete ordinates method. An eigen decomposition approach is then utilized to obtain the closed-form solution of this reduced set of ordinary differential equations. PMID:21369115

Handapangoda, Chintha C; Pathirana, Pubudu N; Premaratne, Malin

2011-02-14

181

Ehrenfest-time dependence of quantum transport corrections and spectral statistics  

NASA Astrophysics Data System (ADS)

The Ehrenfest-time scale in quantum transport separates essentially classical propagation from wave interference and here we consider its effect on the transmission and reflection through quantum dots. In particular, we calculate the Ehrenfest-time dependence of the next-to-leading-order quantum corrections to the transmission and reflection for dc and ac transport and check that our results are consistent with current conservation relations. Looking as well at spectral statistics in closed systems, we finally demonstrate how the contributions analyzed here imply changes in the calculation, given by Brouwer [Phys. Rev. E 74, 066208 (2006)]10.1103/PhysRevE.74.066208, of the next-to-leading order of the spectral form factor. Our semiclassical result coincides with the result obtained by Tian and Larkin [Phys. Rev. B 70, 035305 (2004)]10.1103/PhysRevB.70.035305 by field-theoretical methods.

Waltner, Daniel; Kuipers, Jack

2010-12-01

182

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

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

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

183

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

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

2014-06-15

185

cAMP-dependent protein kinase regulates inhibition of adenosine transport by ethanol.  

PubMed

Ethanol inhibits adenosine uptake, thereby increasing the concentration of extracellular adenosine. Elevation of extracellular adenosine increases intracellular cAMP concentration via activation of adenosine A2 receptors. Extracellular adenosine is also required for the subsequent development of ethanol-induced heterologous desensitization. Here we report that activation of cAMP-dependent protein kinase is necessary for inhibition of adenosine uptake by ethanol and for the consequent accumulation of extracellular adenosine. Ethanol does not inhibit adenosine uptake in mutants of the S49 cell line that lack receptor-stimulated cAMP production (unc cells) or cAMP-dependent protein kinase activity (kin- cells). Forskolin, which bypasses the receptor-coupling defect in unc cells to increase cAMP levels, restores inhibition of adenosine uptake by ethanol. In contrast, in kin- cells forskolin did not restore inhibition of adenosine uptake by ethanol, despite similar increases in cAMP levels. Taken together, these results suggest that cAMP-dependent protein kinase phosphorylates a component of the nucleoside transporter, thereby regulating the sensitivity of adenosine transport to ethanol. PMID:1658611

Nagy, L E; Diamond, I; Gordon, A S

1991-11-01

186

Spin-dependent intergranular transport in magnetite films deposited by ferrite plating  

NASA Astrophysics Data System (ADS)

The present article describes that Fe3-xO4 films prepared by the ferrite plating exhibited negative magnetoresistance associated with spin-dependent intergranular transport. The Fe3-xO4 plated films were composed of Fe3O4 and ?-Fe2O3; the relationship between the degree of oxidation, magnetic and electrical properties by changing the concentration of NaNO2 in the oxidizing solution CNaNO2 was discussed. Current-in-plane (CIP) electrical properties were investigated with a four-probe method at room temperature. Resistivity was about 2-200 ? cm, which is higher than that of bulk magnetite (10-2 ? cm). Negative magnetoresistance with peaks at the coercive field was observed and the MR ratios taken in the maximum field of 2.5 kOe increased up to 5.5% with increasing CNaNO2. Mössbauer spectroscopy and the electrical evaluation showed that an increase in the Fe3+ ion content, in other words, an increase in insulating region raised the resistivity of the films with increasing CNaNO2. The dependence of the MR ratio on CNaNO2 suggested that such insulating region existed in the grain boundaries and the MR effect was caused by the spin-dependent intergranular transport of electrons through the insulating regions. The results suggest that appropriate control of the gain boundaries through changing the oxidizing conditions enables us to improve the MR effect.

Kitamoto, Y.; Nakayama, Y.; Abe, M.

2000-05-01

187

Application of the multigrid amplitude function method for time-dependent transport equation using MOC  

SciTech Connect

An efficient numerical method for time-dependent transport equation, the mutigrid amplitude function (MAF) method, is proposed. The method of characteristics (MOC) is being widely used for reactor analysis thanks to the advances of numerical algorithms and computer hardware. However, efficient kinetic calculation method for MOC is still desirable since it requires significant computation time. Various efficient numerical methods for solving the space-dependent kinetic equation, e.g., the improved quasi-static (IQS) and the frequency transform methods, have been developed so far mainly for diffusion calculation. These calculation methods are known as effective numerical methods and they offer a way for faster computation. However, they have not been applied to the kinetic calculation method using MOC as the authors' knowledge. Thus, the MAF method is applied to the kinetic calculation using MOC aiming to reduce computation time. The MAF method is a unified numerical framework of conventional kinetic calculation methods, e.g., the IQS, the frequency transform, and the theta methods. Although the MAF method is originally developed for the space-dependent kinetic calculation based on the diffusion theory, it is extended to transport theory in the present study. The accuracy and computational time are evaluated though the TWIGL benchmark problem. The calculation results show the effectiveness of the MAF method. (authors)

Tsujita, K.; Endo, T.; Yamamoto, A. [Nagoya University, Department of Material, Physics and Energy Engineering, Furo-cho, Chikusa-ku, Nagoya, 464-8603 (Japan)

2013-07-01

188

Regulation of skeletal muscle sarcolemmal ATP-dependent calcium transport by calmodulin and cAMP-dependent protein kinase.  

PubMed

Skeletal muscle sarcolemma preparations, predominantly in the form of inside-out vesicles, were obtained from porcine muscle by a LiBr-extraction procedure. In the presence of ATP, these preparations were able to accumulate 94 nmol Ca/mg protein after 20 min at 37 degrees C. Sarcolemmal calcium uptake was completely blocked by the calcium ionophore, A23187, but was unaffected by monovalent cation ionophores. Calcium uptake was markedly inhibited by vanadate, with an approximate Ki of 0.5 microM. Oxalate (5 mM) had little effect on the initial phase of calcium uptake, while inorganic phosphate, at concentrations up to 50 mM, had a significant stimulatory effect on sarcolemmal calcium uptake. In contrast to ATP, acetylphosphate had minimal ability and p-nitrophenylphosphate had no ability to support calcium uptake. The maximal initial velocity of skeletal muscle sarcolemmal calcium uptake was 10.0 nmol Ca mg-1 min-1 at 37 degrees C, with a K 1/2 for Ca2+ of 0.88 microM. Addition of either 1 microM calmodulin, or 5 microM cAMP and 0.1 mg/ml cAMP-dependent protein kinase, increased the Vmax to 12.5 and 12.8 nmol Ca mg-1 min-1, respectively, and decreased the K 1/2 for Ca2+ to 0.67 and 0.70 microM, respectively; simultaneous addition of calmodulin and cAMP-dependent protein kinase increased the Vmax to 15.2 nmol Ca mg-1 min-1 and further lowered the K 1/2 to 0.51 microM. When concentrations of NaCl from 10 to 60 mM were added to vesicles that had been loaded with calcium in the presence of ATP, an immediate release of calcium occurred. This process had an approximate K 1/2 for sodium of 10-20 mM and an approximate maximal rate of 50 nmol Ca mg-1 min-1. We conclude that skeletal muscle sarcolemma contains a cAMP-dependent protein kinase- and calmodulin-stimulatable ATP-dependent calcium transport, as well as a sodium: calcium exchange activity. PMID:3931553

Mickelson, J R; Beaudry, T M; Louis, C F

1985-10-01

189

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

190

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

PubMed

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

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

2015-02-01

191

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

Microsoft Academic Search

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

Francisco Castaneda; Rolf K.-H. Kinne

2005-01-01

192

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

Microsoft Academic Search

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

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

1990-01-01

193

Spin-dependent intergranular transport in magnetite films deposited by ferrite plating  

Microsoft Academic Search

The present article describes that Fe3-xO4 films prepared by the ferrite plating exhibited negative magnetoresistance associated with spin-dependent intergranular transport. The Fe3-xO4 plated films were composed of Fe3O4 and gamma-Fe2O3 the relationship between the degree of oxidation, magnetic and electrical properties by changing the concentration of NaNO2 in the oxidizing solution CNaNO2 was discussed. Current-in-plane (CIP) electrical properties were investigated

Y. Kitamoto; Y. Nakayama; M. Abe

2000-01-01

194

Axisymmetry and azimuthal modes in jet noise Havard Vold  

E-print Network

to model both axisymmetric as well as noncircular nozzles. Nomenclature ¯GPP Improved spectral estimator(r) Azimuthal mode coefficient P Helical spectrum Z The set of integers Generic frequency variable Azimuthal of azimuthal wave number m D Diameter of jet nozzle E() The expectation operator gn(r1, x1, r2, x2) Fourier

Papamoschou, Dimitri

195

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

E-print Network

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

Chu, Shih-I; Zhou, Zhongyuan

2009-10-27

196

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

SciTech Connect

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, E-mail: simchi@iust.ac.ir [Department of Physics, Iran University of Science and Technology, Narmak, Tehran 16844 (Iran, Islamic Republic of); Semiconductor Technology Center, Tehran 16844 (Iran, Islamic Republic of); Esmaeilzadeh, Mahdi, E-mail: mahdi@iust.ac.ir; Mazidabadi, Hossein [Department of Physics, Iran University of Science and Technology, Narmak, Tehran 16844 (Iran, Islamic Republic of)

2014-01-28

197

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

198

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

PubMed

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

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

2009-09-01

199

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

PubMed

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

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

2014-09-01

200

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

PubMed Central

Abstract Purpose The objective of this study was to investigate the role of sodium-dependent multiple vitamin transporter (SMVT) on Biotin-Ganciclovir (biotin-GCV) uptake on both human retinal pigmented epithelium cell line (ARPE-19) and rabbit retina. Study also aims to delineate the vitreal pharmacokinetics of biotin-GCV. Method ARPE-19 was employed to study the in vitro uptake experiments. New Zealand white albino rabbits were used to study in vivo retinal uptake and vitreal pharmacokinetics following intravitreal administration of biotin-GCV. In vitro uptake kinetics of [3H] biotin was determined at various initial concentrations. Competitive inhibition studies were conducted in the presence of unlabelled biotin, desthiobiotin, pantothenic acid, and lipoic acid. Various other uptake studies were performed to functionally characterize the transporter. To provide the molecular evidence of this transporter, Reverse Transcription-Polymerase Chain Reaction (RT-PCR) studies were also conducted. In vivo retinal/choroidal uptake studies were carried out with New Zealand albino rabbits. Unconscious animal ocular microdialysis studies were performed in order to evaluate intravitreal pharmacokinetics of GCV and Biotin-GCV. Results Uptake of [3H] biotin into ARPE-19 was linear over 7min, and found to be saturable with Km of 138.25 ?M and Vmax of 38.85 pmol/min/mg protein. Both pantothenic acid and lipoic acid decreased significantly in uptake of biotin in the concentration-dependent manner. Uptake of biotin into ARPE-19 was found to be temperature, energy, and Na+ dependent but Cl? independent. Further, RT-PCR studies identified a band exhibiting presence of hSMVT on ARPE-19. Biotin-GCV is recognized by SMVT system present on the ARPE-19 and rabbit retina. Vitreal Pharmacokinetics profile reveals that most of the parameters were not significantly different for GCV and Biotin-GCV. However, use of Biotin-GCV may result in sustain levels of regenerated GCV in vitreous. Conclusions SMVT was identified and functionally characterized on ARPE-19 cells. Further, Biotin-GCV shares this transport system. Vitreal pharmacokinetics of the conjugate was determined in unconscious rabbit model. PMID:19232011

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

2009-01-01

201

Golgi-dependent transport of cholesterol to the Chlamydia trachomatis inclusion  

PubMed Central

Cholesterol, a lipid not normally found in prokaryotes, was identified in purified Chlamydia trachomatis elementary bodies and in the chlamydial parasitophorous vacuole (inclusion) membrane of infected HeLa cells. Chlamydiae obtained eukaryotic host cell cholesterol both from de novo synthesis or low-density lipoprotein. Acquisition of either de novo-synthesized cholesterol or low-density lipoprotein-derived cholesterol was microtubule-dependent and brefeldin A-sensitive, indicating a requirement for the Golgi apparatus. Transport also required chlamydial protein synthesis, indicative of a pathogen-directed process. The cholesterol trafficking pathway appears to coincide with a previously characterized delivery of sphingomyelin to the inclusion in that similar pharmacological treatments inhibited transport of both sphingomyelin and cholesterol. These results support the hypothesis that sphingomyelin and cholesterol may be cotransported via a Golgi-dependent pathway and that the chlamydial inclusion receives cholesterol preferentially from a brefeldin A-sensitive pathway of cholesterol trafficking from the Golgi apparatus to the plasma membrane. PMID:12743366

Carabeo, Reynaldo A.; Mead, David J.; Hackstadt, Ted

2003-01-01

202

Evidence for Na+ dependent rheogenic HCO3- transport in fused cells of frog distal tubules.  

PubMed

The mechanism of HCO3- transport was studied applying microelectrodes in "giant" cells fused from single epithelial cells of the diluting segment of frog kidney. A sudden increase of extracellular HCO3- concentration from 10 to 20 mmol/l at constant pH hyperpolarized the cell membrane potential of the fused cell. This cell-voltage response was totally abolished by 10(-3) mol/l SITS and significantly reduced by 10(-4) mol/l acetazolamide or by omission of Na+ from the extracellular perfusate. Removal of Na+ from the perfusate caused a transient depolarization. Reapplication of Na+ induced a transient hyperpolarization. 10(-3) mol/l SITS abolished the cell-voltage response to removal and reapplication of Na+. In the intact diluting segment of the isolated perfused frog kidney peritubular perfusion of 10(-4) mol/l acetazolamide reduced the limiting transepithelial electrochemical gradient for H+ significantly from 30 +/- 4 mV to 14 +/- 3 mV. The results suggest: In the diluting segment of the frog kidney a Na+-dependent rheogenic HCO3- transport system exists across the peritubular cell membrane. This rheogenic peritubular Na+/HCO3- cotransporter cooperates with a Na+/H+ exchanger in the luminal membrane, thus driving HCO3- reabsorption. Reabsorption of HCO3- and secretion of H+ depend upon the presence of carbonic anhydrase. PMID:3494986

Wang, W; Dietl, P; Oberleithner, H

1987-03-01

203

Epithelial Organic Cation Transporters Ensure pH-Dependent Drug Absorption in the Airway  

PubMed Central

Most inhaled ?2-adrenergic agonist and anticholinergic bronchodilators have low lipid solubility because of their transient or permanent positive net charge at physiologic pH. Airway absorption of these cationic drugs is incompletely understood. We examined carrier-mediated mechanisms of cationic drug uptake by human airway epithelia. Airway tissues and epithelial cells, obtained from lung donors without preexisting lung disease, were evaluated for organic cation transporter expression by quantitative RT-PCR and immunofluorescence. For in vitro functional studies on primary airway epithelial cells, uptake of the cationic fluorophore 4-[4-(dimethylamino)-styryl]-N-methylpyridinium (ASP+) was characterized. Quantitative RT-PCR analysis demonstrated high mRNA levels for two polyspecific organic cation/carnitine transporters, OCTN1 and OCTN2, in human airway epithelia. Immunofluorescence of human airway sections confirmed OCTN1/2 protein expression, with a predominant localization to the apical portion of epithelial cells. Primary airway epithelial cells showed a carrier-mediated, temperature-sensitive and saturable uptake of ASP+. Seventy-five to eighty percent of ASP+ uptake was inhibited by L-carnitine, an OCTN2-carried zwitterion. The uptake was pH dependent, with ? 3-fold lower rates at acidic (pH 5.7) than at alkaline (pH 8.2) extracellular pH. Albuterol and formoterol inhibited ASP+ uptake, suggesting that all these molecules are carried by the same transport mechanism. These findings demonstrate the existence and functional role of a pH-dependent organic cation uptake machinery, namely OCTN1 and OCTN2, in human airway epithelia. We suggest that epithelial OCTN1/2 are involved in the delivery of inhaled cationic bronchodilators to the airway tissue. PMID:16917073

Horvath, Gabor; Schmid, Nathalie; Fragoso, Miryam A.; Schmid, Andreas; Conner, Gregory E.; Salathe, Matthias; Wanner, Adam

2007-01-01

204

Axial and azimuthal spin-wave eigenmodes in rolled-up permalloy stripes  

NASA Astrophysics Data System (ADS)

We experimentally realized rolled-up permalloy stripes to form three-dimensional ring-like ferromagnetic structures. By means of microwave absorption spectroscopy, we find multiple resonances occurring above a demagnetization field threshold which depends on the ring's axial width. Our experimental data can be well modeled by assuming both axial and azimuthal spin-wave confinement.

Balhorn, Felix; Jeni, Simon; Hansen, Wolfgang; Heitmann, Detlef; Mendach, Stefan

2012-05-01

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

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

PubMed Central

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

Marshall, W S

1981-01-01

207

Decoherent time-dependent transport beyond Landauer-Büttiker: a Quantum Drift alternative to Quantum Jumps  

E-print Network

We present a model for decoherence in time-dependent transport. It boils down into a form of wave function that undergoes a smooth stochastic drift of the phase in a local basis, the Quantum Drift (QD) model. This drift is nothing else but a local energy fluctuation. Unlike Quantum Jumps (QJ) models, no jumps are present in the density as the evolution is unitary. As a first application, we address the transport through a resonant state $\\left\\vert 0\\right\\rangle $ that undergoes decoherence. We show the equivalence with the decoherent steady state transport in presence of a B\\"{u}ttiker's voltage probe. In order to test the dynamics, we consider two many-spin systems whith a local energy fluctuation. A two-spin system is reduced to a two level system (TLS) that oscillates among $\\left\\vert 0\\right\\rangle $ $\\equiv $ $ \\left\\vert \\uparrow \\downarrow \\right\\rangle $ and $\\left\\vert 1\\right\\rangle \\equiv $ $\\left\\vert \\downarrow \\uparrow \\right\\rangle $. We show that QD model recovers not only the exponential damping of the oscillations in the low perturbation regime, but also the non-trivial bifurcation of the damping rates at a critical point, i.e. the quantum dynamical phase transition. We also address the spin-wave like dynamics of local polarization in a spin chain. The QD average solution has about half the dispersion respect to the mean dynamics than QJ. By evaluating the Loschmidt Echo (LE), we find that the pure states $\\left\\vert 0\\right\\rangle $ and $\\left\\vert 1\\right \\rangle $ are quite robust against the local decoherence. In contrast, the LE, and hence coherence, decays faster when the system is in a superposition state. Because its simple implementation, the method is well suited to assess decoherent transport problems as well as to include decoherence in both one-body and many-body dynamics.

Lucas J. Fernández-Alcázar; Horacio M. Pastawski

2015-01-26

208

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

209

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

210

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

211

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

PubMed

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

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

2014-07-31

212

Simulations of the nonlinear dose dependence for substrates of influx and efflux transporters in the human intestine.  

PubMed

The purpose of this study was to develop simulation and modeling methods for the evaluation of pharmacokinetics when intestinal influx and efflux transporters are involved in gastrointestinal absorption. The advanced compartmental absorption and transit (ACAT) model as part of the computer program GastroPlus was used to simulate the absorption and pharmacokinetics of valacyclovir, gabapentin, and talinolol. Each of these drugs is a substrate for an influx or efflux transporter and all show nonlinear dose dependence within the normal therapeutic range. These simulations incorporated the experimentally derived gastrointestinal distributions of transporter expression levels for oligopeptide transporters PepT1 and HPT1 (valacyclovir); System L-amino acid transporter LAT2 and organic cation transporter OCTN1 (gabapentin); and organic anion transporter (OATP1A2) and P-glycoprotein (talinolol). By assuming a uniform distribution of oligopeptide transporter and by application of the in vitro K(m) value for valacyclovir, the simulations accurately reproduced the experimental nonlinear dose dependence. For gabapentin, LAT2 distribution produced simulation results that were much more accurate than OCTN1 distributions. For talinolol, an influx transporter distribution for OATP1A2 and the efflux transporter P-glycoprotein distributed with increasing expression in the distal small intestine produced the best results. The physiological characteristics of the small and large intestines used in the ACAT model were able to accurately account for the positional and temporal changes in concentration and carrier-mediated transport of the three drugs included in this study. The ACAT model reproduced the nonlinear dose dependence for each of these drugs. PMID:19434502

Bolger, Michael B; Lukacova, Viera; Woltosz, Walter S

2009-06-01

213

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

NASA Astrophysics Data System (ADS)

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

Zhong, Zhaopeng

214

The dynamic association of RCC1 with chromatin is modulated by Ran-dependent nuclear transport.  

PubMed

Regulator of chromosome condensation (RCC1) binding to chromatin is highly dynamic, as determined by fluorescence recovery after photobleaching analysis of GFP-RCC1 in stably transfected tsBN2 cells. Microinjection of wild-type or Q69L Ran markedly slowed the mobility of GFP-RCC1, whereas T24N Ran (defective in nucleotide loading) decreased it further still. We found significant alterations in the mobility of intranuclear GFP-RCC1 after treatment with agents that disrupt different Ran-dependent nuclear export pathways. Leptomycin B, which inhibits Crm1/RanGTP-dependent nuclear export, significantly increased the mobility of RCC1 as did high levels of actinomycin D (to inhibit RNA polymerases I, II, and III) or alpha-amanitin (to inhibit RNA polymerases II and III) as well as energy depletion. Inhibition of just mRNA transcription, however, had no affect on GFP-RCC1 mobility consistent with mRNA export being a Ran-independent process. In permeabilized cells, cytosol and GTP were required for the efficient release of GFP-RCC1 from chromatin. Recombinant Ran would not substitute for cytosol, and high levels of supplemental Ran inhibited the cytosol-stimulated release. Thus, RCC1 release from chromatin in vitro requires a factor(s) distinct from, or in addition to, Ran and seems linked in vivo to the availability of Ran-dependent transport cargo. PMID:14565978

Cushman, Ian; Stenoien, David; Moore, Mary Shannon

2004-01-01

215

The Dynamic Association of RCC1 with Chromatin Is Modulated by Ran-dependent Nuclear Transport  

PubMed Central

Regulator of chromosome condensation (RCC1) binding to chromatin is highly dynamic, as determined by fluorescence recovery after photobleaching analysis of GFP-RCC1 in stably transfected tsBN2 cells. Microinjection of wild-type or Q69L Ran markedly slowed the mobility of GFP-RCC1, whereas T24N Ran (defective in nucleotide loading) decreased it further still. We found significant alterations in the mobility of intranuclear GFP-RCC1 after treatment with agents that disrupt different Ran-dependent nuclear export pathways. Leptomycin B, which inhibits Crm1/RanGTP-dependent nuclear export, significantly increased the mobility of RCC1 as did high levels of actinomycin D (to inhibit RNA polymerases I, II, and III) or ?-amanitin (to inhibit RNA polymerases II and III) as well as energy depletion. Inhibition of just mRNA transcription, however, had no affect on GFP-RCC1 mobility consistent with mRNA export being a Ran-independent process. In permeabilized cells, cytosol and GTP were required for the efficient release of GFP-RCC1 from chromatin. Recombinant Ran would not substitute for cytosol, and high levels of supplemental Ran inhibited the cytosol-stimulated release. Thus, RCC1 release from chromatin in vitro requires a factor(s) distinct from, or in addition to, Ran and seems linked in vivo to the availability of Ran-dependent transport cargo. PMID:14565978

Cushman, Ian; Stenoien, David; Moore, Mary Shannon

2004-01-01

216

Structural phase-dependent hole localization and transport in bismuth vanadate  

NASA Astrophysics Data System (ADS)

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

Kweon, Kyoung E.; Hwang, Gyeong S.

2013-05-01

217

Apical sodium-dependent bile acid transporter upregulation is associated with necrotizing enterocolitis.  

PubMed

Necrotizing enterocolitis (NEC) is the most common gastrointestinal emergency of premature infants. Previously, we showed that luminal bile acids (BAs) are increased and correlated with disease development and that the apical sodium-dependent BA transporter (ASBT), which transports BAs from the ileal lumen into enterocytes, is upregulated in rats with NEC. We hypothesized that intraenterocyte, rather than luminal, BAs are associated with NEC and that upregulation of ASBT may be a mechanism by which this occurs. Neonatal rats with or without the ASBT inhibitor SC-435, mice in which ASBT was knocked out, and mice that overproduce BAs were subjected to the NEC protocol. Disease development, ASBT, and the farnesoid X receptor protein, along with luminal and intraenterocyte BA levels, were assessed. In addition, ileal sections from premature infants with and without NEC were examined for ASBT via immunohistology and real-time PCR. When BAs were not transported into enterocytes (rats given SC-435 and ASBT knockout mice), severity and incidence of NEC were reduced. In contrast, in mice that overproduce BAs, ASBT was elevated, intraenterocyte BAs were increased, and disease development was increased. ASBT staining was more intense on the apical membrane of ileal enterocytes from premature infants with NEC than premature infants with non-NEC diagnoses. In addition, ASBT mRNA levels were significantly higher in infants with NEC. These data show that accumulation of intraenterocyte BAs contributes to disease development, elevated ASBT increases disease severity in experimental models of NEC, and ASBT is elevated in human NEC. These data confirm that BAs and upregulation of ASBT play a crucial role in NEC pathogenesis and suggest that inhibition of ASBT could be utilized as a therapeutic modality against this disease. PMID:20616306

Halpern, Melissa D; Weitkamp, Jörn-Hendrik; Mount Patrick, Sarah K; Dobrenen, Holly J; Khailova, Ludmila; Correa, Hernan; Dvorak, Bohuslav

2010-09-01

218

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

Microsoft Academic Search

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

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

1995-01-01

219

Using an electronic compass to determine telemetry azimuths  

USGS Publications Warehouse

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

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

2002-01-01

220

Spin-dependent electron transport in protein-like single-helical molecules.  

PubMed

We report on a theoretical study of spin-dependent electron transport through single-helical molecules connected by two nonmagnetic electrodes, and explain the experiment of significant spin-selective phenomenon observed in ?-helical protein and the contradictory results between the protein and single-stranded DNA. Our results reveal that the ?-helical protein is an efficient spin filter and the spin polarization is robust against the disorder. These results are in excellent agreement with recent experiments [Mishra D, et al. (2013) Proc Natl Acad Sci USA 110(37):14872-14876; Göhler B, et al. (2011) Science 331(6019):894-897] and may facilitate engineering of chiral-based spintronic devices. PMID:25071198

Guo, Ai-Min; Sun, Qing-Feng

2014-08-12

221

The spin-dependent transport of Co-encapsulated Si nanotubes contacted with Cu electrodes  

SciTech Connect

Unlike carbon nanotubes, silicon ones are hard to form. However, they could be stabilized by metal-encapsulation. Using first-principles calculations, we investigate the spin-dependent electronic transport of Co-encapsulated Si nanotubes, which are contacted with Cu electrodes. For the finite tubes, as the tube-length increases, the transmission changes from spin-unpolarized to spin-polarized. Further analysis shows that, not only the screening of electrodes on Co's magnetism but also the spin-asymmetric Co-Co interactions are the physical mechanisms. As Cu and Si are the fundamental elements in semiconductor industry, our results may throw light on the development of silicon-based spintronic devices.

Guo, Yan-Dong; Yan, Xiao-Hong, E-mail: xhyan@nuaa.edu.cn [College of Science, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); College of Electronic Science and Engineering, Nanjing University of Posts and Telecommunications, Nanjing 210046 (China); Xiao, Yang [College of Science, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China)

2014-02-10

222

The spin-dependent transport of Co-encapsulated Si nanotubes contacted with Cu electrodes  

NASA Astrophysics Data System (ADS)

Unlike carbon nanotubes, silicon ones are hard to form. However, they could be stabilized by metal-encapsulation. Using first-principles calculations, we investigate the spin-dependent electronic transport of Co-encapsulated Si nanotubes, which are contacted with Cu electrodes. For the finite tubes, as the tube-length increases, the transmission changes from spin-unpolarized to spin-polarized. Further analysis shows that, not only the screening of electrodes on Co's magnetism but also the spin-asymmetric Co-Co interactions are the physical mechanisms. As Cu and Si are the fundamental elements in semiconductor industry, our results may throw light on the development of silicon-based spintronic devices.

Guo, Yan-Dong; Yan, Xiao-Hong; Xiao, Yang

2014-02-01

223

Structure-dependent optical and electrical transport properties of nanostructured Al-doped ZnO.  

PubMed

The structure-property relation of nanostructured Al-doped ZnO thin films has been investigated in detail through a systematic variation of structure and morphology, with particular emphasis on how they affect optical and electrical properties. A variety of structures, ranging from compact polycrystalline films to mesoporous, hierarchically organized cluster assemblies, are grown by pulsed laser deposition at room temperature at different oxygen pressures. We investigate the dependence of functional properties on structure and morphology and show how the correlation between electrical and optical properties can be studied to evaluate energy gap, conduction band effective mass and transport mechanisms. Understanding these properties opens up opportunities for specific applications in photovoltaic devices, where optimized combinations of conductivity, transparency and light scattering are required. PMID:22914557

Gondoni, P; Ghidelli, M; Di Fonzo, F; Carminati, M; Russo, V; Li Bassi, A; Casari, C S

2012-09-14

224

Spin-Dependent Electron Transport Through a Three-Terminal Mesoscopic Spin-Orbit Coupled Systems  

NASA Astrophysics Data System (ADS)

We studied theoretically the spin-dependent electron transport properties of a three-terminal nanostructure proposed by Xiao and Chen [J. Appl. Phys.1, 108 (2010)]. The spin-resolved recursive Green's function method is used to calculate the three-terminal spin-polarization. We focus on the influence both of the structural parameters and Rashba spin-orbit coupling (SOC) strength in the investigated system. It is shown that the spin-polarization is still a reasonable value for being observable in experiment with small Rashba SOC strength and longer length of the wide region in the investigated system. The underlying physics is revealed to originate from the effect of SOC-induced effective magnetic field at the structure-induced Fano resonance. This length of the middle wide region in three-terminal nanostructure can be more easily fabricated experimentally.

Xu, Zhonghui; Xiao, Xianbo; Chen, Yuguang

2013-03-01

225

Spin-dependent thermoelectronic transport of a single molecule magnet Mn(dmit){sub 2}  

SciTech Connect

We investigate spin-dependent thermoelectronic transport properties of a single molecule magnet Mn(dmit){sub 2} sandwiched between two Au electrodes using first-principles density functional theory combined with nonequilibrium Green's function method. By applying a temperature difference between the two Au electrodes, spin-up and spin-down currents flowing in opposite directions can be induced due to asymmetric distribution of the spin-up and spin-down transmission spectra around the Fermi level. A pure spin current and 100% spin polarization are achieved by tuning back-gate voltage to the system. The spin caloritronics of the molecule with a perpendicular conformation is also explored, where the spin-down current is blocked strongly. These results suggest that Mn(dmit){sub 2} is a promising material for spin caloritronic applications.

Su, Zhongbo; Wei, Xinyuan; Yang, Zhongqin, E-mail: zyang@fudan.edu.cn [State Key Laboratory of Surface Physics and Key Laboratory for Computational Physical Sciences (MOE) and Department of Physics, Fudan University, Shanghai 200433 (China); An, Yipeng [College of Physics and Electronic Engineering and Institute of Computational Materials Design, Henan Normal University, Xinxiang 453007 (China)

2014-05-28

226

Environmental effects on temperature-dependent carrier transports in poly(3-hexylthiophene) films  

NASA Astrophysics Data System (ADS)

Applications of poly(3-hexylthiophene) (P3HT) to solar cells have been reported. The reliability of organic solar cells is a key factor of full-scale applications in commercial optoelectronics. In this study, the environmental effect on the carrier transport in P3HT is researched. Charge-trapping phenomena are studied through time-domain measurement for P3HT thin-film transistors. The time-domain data confirm the hole-trapping model, indicating that water vapor influences the response by producing additional hole traps that serve to increase the current time constant. To understand the P3HT degradation mechanisms, an analysis through the temperature-dependent transfer characteristics is presented. It is shown that the hopping conduction behavior can be affected by exposure to ambient humidity and ambient atmosphere, inducing fluctuations in the hopping distance and the barrier height for hopping that serve to influence the carrier mobility.

Lin, Yow-Jon; Chin, Yi-Min; Chang, Hsing-Cheng

2015-01-01

227

Apoptosis is regulated by the rate of glucose transport in an interleukin 3 dependent cell line  

PubMed Central

In the absence of a survival stimulus, the interleukin 3 (IL-3)- dependent IC.DP cell line undergoes a process termed programmed cell death or apoptosis. Survival can be induced by IL-3, which can also stimulate proliferation of IC.DP cells. IC.DP cells have been stably transfected with the p160v-abl protein tyrosine kinase, activation of the kinase at the permissive temperature permits cell survival in the absence of IL-3 by suppression of apoptosis, although the growth factor is still required for proliferation. Both IL-3 and activation of the v- ABL tyrosine kinase stimulated glucose transport, which may in part be due to a translocation of transporters to the cell surface. Inhibition of glucose uptake markedly increased the rate of apoptosis in these cells, an effect that could be reversed by the provision of alternative energy sources such as glutamine. Growth factor- or oncogene-mediated increases in glucose uptake may therefore represent an important regulatory point in the suppression of apoptosis. PMID:8064240

1994-01-01

228

Time-dependent macrodispersion for solute transport in anisotropic heterogeneous aquifers  

NASA Astrophysics Data System (ADS)

The expected values of the spatial second-order moments of a solute body transported by groundwater are derived for flow through heterogeneous formations of a stationary random anisotropic structure. They are based on a general formulation, which reduces to most existing results in the literature as particular cases. Detailed results are given for the spatial variance as a function of time in the case of axisymmetric anisotropy, average flow parallel to the plane of isotropy, first-order approximation in the log conductivity variance ?Y2, and high Peclet numbers. These results fill the gap existing between the studies of Dagan (1982, 1984), on one hand, and those of Gelhar and Axness (1983) and Neuman et al. (1987), on the other. A preliminary investigation of the higher-order effects in ?Y2 suggests that the use of the first-order approximations is warranted, at present, only for ?Y2 ? 1. The impact of the errors of estimation of the parameters on which transport depends is briefly analyzed.

Dagan, Gedeon

1988-09-01

229

A new multidimensional, energy-dependent two-moment transport code for neutrino-hydrodynamics  

E-print Network

We present the new code ALCAR developed to model multidimensional, multi energy-group neutrino transport in the context of supernovae and neutron-star mergers. The algorithm solves the evolution equations of the 0th- and 1st-order angular moments of the specific intensity, supplemented by an algebraic relation for the 2nd-moment tensor to close the system. The scheme takes into account frame-dependent effects of order O(v/c) as well as the most important types of neutrino interactions. The transport scheme is significantly more efficient than a multidimensional solver of the Boltzmann equation, while it is more accurate and consistent than the flux-limited diffusion method. The finite-volume discretization of the essentially hyperbolic system of moment equations employs methods well-known from hydrodynamics. For the time integration of the potentially stiff moment equations we employ a scheme in which only the local source terms are treated implicitly, while the advection terms are kept explicit, thereby allo...

Just, Oliver; Janka, H -Thomas

2015-01-01

230

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

231

Temperature-dependent coherent carrier transport in quantum cascade lasers This article has been downloaded from IOPscience. Please scroll down to see the full text article.  

E-print Network

Temperature-dependent coherent carrier transport in quantum cascade lasers This article has been of Physics Temperature-dependent coherent carrier transport in quantum cascade lasers Muhammad Anisuzzaman carrier transport in quantum cascade lasers (QCLs) is studied in this paper. It was found that coherent

Maryland, Baltimore County, University of

232

Type 2 (non-insulin-dependent) diabetes mellitus and glucose transporter gene ( GLUT 1 and GLUT 4 ) polymorphism  

Microsoft Academic Search

Glucose transporter genes have been proposed as candidate genes for type 2 (non-insulin-dependent) diabetes mellitus. We chose to study the adult skeletal muscle glucose transporter gene (GLUT 4) andGLUT 1 in consideration of previous conflicting results obtained by different authors. We studied 68 patients with type 2 diabetes, and 66 non-diabetic controls matched for age, sex, and body mass index

C. Magnani; F. Capra; A. Calderara; P. A. Bonini; R. Taramelli; M. Ferrari; A. E. Pontiroli

1992-01-01

233

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

PubMed Central

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

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

2013-01-01

234

Phorbol myristate acetate stimulates ATP-dependent calcium transport by the plasma membrane of neutrophils.  

PubMed Central

We studied the effect of phorbol myristate acetate (PMA) on the plasma membrane ATP-dependent calcium pump in neutrophils. Plasma membrane-enriched fractions ("podosomes") from PMA-stimulated guinea pig neutrophils exhibited a twofold stimulation of ATP-dependent calcium transport when compared with control podosomes. The stimulatory effect was rapid (beginning less than 2 min after exposure to PMA) and reached maximal values within 5 min. PMA increased the maximum velocity but not the affinity of the calcium pump for Ca++. Pump activation was not preceded by a rise in cytosolic free calcium concentration [Ca++]i, as assessed by the intracellularly trapped fluorescent calcium indicator Quin 2, but instead slightly lowered [Ca++]i and prevented the rise in [Ca++]i normally induced by the chemotactic peptide formyl-methionyl-leucyl-phenylalanine. These results suggest that the calcium pump in the plasma membrane of neutrophils may be stimulated by calcium-independent pathways, and that this activation could be one of the earliest events mediating some of the effects of phorbol esters. PMID:6323530

Lagast, H; Pozzan, T; Waldvogel, F A; Lew, P D

1984-01-01

235

Nuclear transport of protein TTC4 depends on the cell cycle.  

PubMed

TTC4 (tetratricopeptide repeat domain protein 4) is a putative tumor suppressor involved in the transformation of melanocytes. At present, the relationships between TTC4 and DNA replication proteins are largely unknown, as are the tissue distribution and subcellular localization of TTC4. Using reverse transcription with the polymerase chain reaction, we have observed that the murine TTC4 gene is ubiquitously expressed. Analysis of the TTC4 subcellular localization has shown that, upon overexpression, TTC4 localizes to the cytoplasm. Interestingly, co-expression with a known protein interaction partner, hampin/MSL1, results in the nuclear translocation of the TTC4 protein. The subcellular localization of endogenous TTC4 depends, however, on the cell cycle: it is mostly nuclear in the G1 and S phases and is evenly distributed between the nucleus and cytoplasm in G2. The nuclear transport of TTC4 is apparently a complex process dependent on interactions with other proteins during the progression of the cell cycle. Thus, the dynamic character of the nuclear accumulation of TTC4 might be a potential link with regard to its function in tumor suppression. PMID:19390865

Dmitriev, Ruslan I; Okkelman, Irina A; Abdulin, Roman A; Shakhparonov, Mikhail I; Pestov, Nikolay B

2009-06-01

236

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

PubMed Central

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

2013-01-01

237

Long-range azimuthal correlations in proton-proton and proton-nucleus collisions from the incoherent scattering of partons  

NASA Astrophysics Data System (ADS)

We show that the incoherent elastic scattering of partons, as present in a multi-phase transport model (AMPT), with a modest parton-parton cross-section of ? = 1.5- 3 mb, naturally explains the long-range two-particle azimuthal correlation as observed in proton-proton and proton-nucleus collisions at the Large Hadron Collider.

Ma, Guo-Liang; Bzdak, Adam

2014-12-01

238

Long-range azimuthal correlations in proton-proton and proton-nucleus collisions from the incoherent scattering of partons  

E-print Network

We show that the incoherent elastic scattering of partons, as present in a multi-phase transport model (AMPT), with a modest parton-parton cross-section of $\\sigma=1.5 - 3$ mb, naturally explains the long-range two-particle azimuthal correlation as observed in proton-proton and proton-nucleus collisions at the Large Hadron Collider.

Guo-Liang Ma; Adam Bzdak

2014-11-13

239

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

PubMed

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

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

2012-05-15

240

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

241

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

242

Independent control of polar and azimuthal anchoring.  

PubMed

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

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

2013-07-01

243

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

PubMed

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

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

2003-09-01

244

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

PubMed Central

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

Matsuoka, Ken

2013-01-01

245

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

NASA Astrophysics Data System (ADS)

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

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

2012-09-01

246

Sweepless time-dependent transport calculations using the staggered block Jacobi method  

SciTech Connect

The Staggered-Block Jacobi (SBJ) method is a new numerical SN transport method for solving time-dependent problems without sweeps or low-order acceleration. Because it is a Jacobian method, it is trivial to parallelize and will scale linearly with the number of processors, It is highly accurate in thick-diffusive problems and unconditionally stable when combined with the lumped linear discontinuous finite element spatial discretization. In this way, the SBJ method is complementary to sweep-based methods, which are accurate and efficient in thin, streaming regions but inefficient in thick, diffusive problems without acceleration. We have extended previous work by demonstrating how sweep-based methods and the SBJ method may be combined to produce a method which is accurate and efficient without acceleration in all optical thicknesses while still retaining good parallel efficiency. Furthermore, iterations may also be added to the SBJ method. This is particularly useful for improving the accuracy of the SBJ method in intermediate-thickness problems.

Davidson, G [Los Alamos National Laboratory; Larsen, E W [Los Alamos National Laboratory

2009-01-01

247

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

248

Relationships of CDXs and apical sodium-dependent bile acid transporter in Barrett’s esophagus  

PubMed Central

Barrett’s esophagus (BE) is characterized by intestinal metaplasia with the differentiated epithelium replaced by another type of epithelium morphologically similar to normal intestinal epithelium. The metaplasia is preceded by bile and acid reflux into the esophagus. BE is a premalignant condition associated with increased risk of esophageal cancer, especially esophageal adenocarcinoma. The Caudal-related homeodomain transcription factors Caudal-related homeodomain transcription factor CDX1 and CDX2 are expressed exclusively in the small and large intestine, playing important roles in proliferation and differentiation of intestinal epithelial cells. Ectopic expression of CDX1 and CDX2 occurs in BE. The apical sodium-dependent bile acid transporter (ASBT) is expressed primarily in terminal ileum where it is a key factor for intestinal reabsorption of bile salts. In addition to upregulation of CDX1 and CDX2, ASBT expression is up-regulated in BE. Furthermore, both CDX1/CDX2 and ASBT expressions are down-regulated in high-grade esophageal dysplasia. The alteration of the above-mentioned factors calls for attention: what is the relationship between CDXs and ASBT aberrant expression in BE? In this commentary, we discuss this issue on basis of the recent study done by Ma et al. PMID:23687410

Zhao, Jingbo; Gregersen, Hans

2013-01-01

249

Relationships of CDXs and apical sodium-dependent bile acid transporter in Barrett's esophagus.  

PubMed

Barrett's esophagus (BE) is characterized by intestinal metaplasia with the differentiated epithelium replaced by another type of epithelium morphologically similar to normal intestinal epithelium. The metaplasia is preceded by bile and acid reflux into the esophagus. BE is a premalignant condition associated with increased risk of esophageal cancer, especially esophageal adenocarcinoma. The Caudal-related homeodomain transcription factors Caudal-related homeodomain transcription factor CDX1 and CDX2 are expressed exclusively in the small and large intestine, playing important roles in proliferation and differentiation of intestinal epithelial cells. Ectopic expression of CDX1 and CDX2 occurs in BE. The apical sodium-dependent bile acid transporter (ASBT) is expressed primarily in terminal ileum where it is a key factor for intestinal reabsorption of bile salts. In addition to upregulation of CDX1 and CDX2, ASBT expression is up-regulated in BE. Furthermore, both CDX1/CDX2 and ASBT expressions are down-regulated in high-grade esophageal dysplasia. The alteration of the above-mentioned factors calls for attention: what is the relationship between CDXs and ASBT aberrant expression in BE? In this commentary, we discuss this issue on basis of the recent study done by Ma et al. PMID:23687410

Zhao, Jingbo; Gregersen, Hans

2013-05-14

250

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

PubMed Central

Serial MRI human brain scans have facilitated the detection of brain development and of the earliest signs of neuropsychiatric and neurodegenerative diseases, monitoring disease progression, and resolving drug effects in clinical trials for preventing or slowing the rate of brain degeneration. To track anatomical shape changes in serial images, we introduce new point-based time sequence large deformation diffeomorphic metric mapping (TS-LDDMM) to infer the time flow of within-subject geometric shape changes that carry known observations through a period. Its Euler-Lagrange equation is generalized for anatomies whose shapes are characterized by point sets, such as landmarks, curves, and surfaces. The time-dependent momentum obtained from the TS-LDDMM encodes within-subject shape changes. For the purpose of across-subject shape comparison, we then propose a diffeomorphic analysis framework to translate within-subject deformation in a global template without incorporating across-subject anatomical variations via parallel transport technique. The analysis involves the retraction of the within-subject timedependent momentum along the TS-LDDMM trajectory from each time to the baseline, the translation of the momentum in a global template, and the reconstruction of the TS-LDDMM trajectory starting from the global template. PMID:19041947

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

2009-01-01

251

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

252

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

253

Electron carrier concentration dependent magnetization and transport properties in ZnO:Co diluted magnetic semiconductor thin films  

E-print Network

for ferromagnetic exchange in ZnO:Co diluted magnetic semiconductor materials. © 2008 American Institute of PhysicsElectron carrier concentration dependent magnetization and transport properties in ZnO:Co diluted October 2008; published online 4 December 2008 Diluted magnetic semiconducting ZnO:Co thin films

Yang, Zheng

254

Incongruent, time-dependent chemical vapour transport in multi-component systems: A case study in Cr-Ge-Si  

NASA Astrophysics Data System (ADS)

Single crystals of various compounds in the ternary system Cr-Ge-Si were grown by chemical vapour transport (CVT) with iodine in a temperature gradient from 800 to 1000 °C. The transport of the solid solution phases Cr(Ge,Si) 3 and Cr 5(Ge,Si) 3 was found to be strongly incongruent and time-dependent. While individual sink crystals are homogeneous and do not show any composition gradient (core-shell structure), the sink a whole is strongly inhomogeneous showing a uniform distribution crystal compositions over a wide composition range. Possible explanations for the observed transport mechanism and implications for synthetic use of incongruent transport systems are discussed. An isothermal section of the ternary phase diagram at 800 °C is given.

Jandl, Isabella; Richter, Klaus W.; Ipser, Herbert

2011-05-01

255

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

256

Object detection by correlation coefficients using azimuthally averaged reference projections  

Microsoft Academic Search

A method of computing correlation coefficients for object detection that takes advantage of using azimuthally averaged reference projections is described and compared with two alternative methods-computing a cross-correlation function or a local correlation coefficient versus the azimuthally averaged reference projections. Two examples of an application from structural biology involving the detection of projection views of biological macromolecules in electron micrographs

William V. Nicholson

2004-01-01

257

Original article Do changes in the azimuthal distribution of maize  

E-print Network

Original article Do changes in the azimuthal distribution of maize leaves over time affect canopy, 86600 Lusignan, France (Received 16 September 1998; accepted 22 February 1999) Abstract - In maize are distributed uniformly. Once we had demonstrated azimuthal re-orientation of maize leaves during the vegetative

Paris-Sud XI, Université de

258

Quality control and substrate-dependent downregulation of the nutrient transporter Fur4.  

PubMed

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

2013-04-01

259

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

260

Partial purification of the Na + -dependent d -glucose transport system from renal brush border membranes  

Microsoft Academic Search

Summary  A membrane extract enriched with the Na+-dependentd-glucose transport system was obtained by differential cholate solubilization of rat renal brush border membranes in the presence of 120mm Na+ ions. Sodium ions were essential in stabilizing the transport system during cholate treatment. This membrane extract was further purified with respect to its Na+-coupledd-glucose transport activity and protein content by the use of

Wha Bin Ira; Kit Yin Ling; Robert G. Faust

1982-01-01

261

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

262

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

263

Soft Gluon Resummations in Dijet Azimuthal Angular Correlations in Hadronic Collisions  

NASA Astrophysics Data System (ADS)

We derive all order soft gluon resummation in dijet azimuthal angular correlation in hadronic collisions at the next-to-leading logarithmic level. The relevant coefficients for the Sudakov resummation factor, the soft and hard factors, are calculated. The theory predictions agree well with the experimental data from D0 Collaboration at the Tevatron. This provides a benchmark calculation for the transverse momentum dependent QCD resummation for jet productions in hadron collisions.

Sun, Peng; Yuan, C.-P.; Yuan, Feng

2014-12-01

264

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

265

Localization of type-III sodium-dependent phosphate transporter 2 in the mouse brain.  

PubMed

Type-III sodium-dependent phosphate transporters 1 and 2 (PiT-1 and PiT-2, respectively) are proteins encoded by SLC20A1 and SLC20A2, respectively. The ubiquitous distribution of PiT-1 and PiT-2 mRNAs in mammalian tissues is in agreement with the housekeeping maintenance of homeostasis of intracellular inorganic phosphate (Pi), which is absorbed from interstitial fluid for normal cellular functions. Recently, mutations of SLC20A2 have been found in patients with idiopathic basal ganglia calcification (IBGC), also known as Fahr's disease. However, the localization of PiT-2 in the brain has not been clarified yet. Therefore, the aim of this study is to clarify the distribution of PiT-2 expression in the mouse brain. Our biochemical and immunohistochemical analyses using a polyclonal antibody (Ab) and a monoclonal Ab showed that PiT-2 was ubiquitously expressed throughout the brain. In terms of the cellular type, PiT-2 was predominantly detected in neurons; it colocalized with ?-tubulin III in the cerebral cortex and with calbindin D-28K in Purkinje cells. Additionally, PiT-2 immunopositivity was detected in the microtubule-associated protein 2-positive neuronal dendrites in the cerebral cortex. However, colocalization with PiT-2 immunopositivity was not observed in the synaptophysin-positive nerve terminals. PiT-2 was also expressed in astrocytes and vascular endothelial cells. Our results indicate that PiT-2 plays an important role in the maintenance of cellular Pi homeostasis in neurons, astrocytes, and endothelial cells. This finding is a milestone in the study of the function of PiT-2 in the normal mouse brain and particularly in the brains of patients with Fahr's disease. PMID:23911649

Inden, Masatoshi; Iriyama, Masaki; Takagi, Mari; Kaneko, Masayuki; Hozumi, Isao

2013-09-19

266

Gabapentin increases extracellular glutamatergic level in the locus coeruleus via astroglial glutamate transporter-dependent mechanisms.  

PubMed

Gabapentin has shown to be effective in animals and humans with acute postoperative and chronic pain. Yet the mechanisms by which gabapentin reduces pain have not been fully addressed. The current study performed in vivo microdialysis in the locus coeruleus (LC) in normal and spinal nerve ligated (SNL) rats to examine the effect of gabapentin on extracellular glutamate concentration and its mechanisms of action with focus on presynaptic GABA-B receptors, astroglial glutamate transporter-1 (GLT-1), and interactions with ?2? subunits of voltage-gated Ca(2+) channels and endogenous noradrenaline. Basal extracellular concentration and tissue content of glutamate in the LC were greater in SNL rats than normal ones. Intravenously administered and LC-perfused gabapentin increased extracellular glutamate concentration in the LC. The net amount of glutamate increased by gabapentin is larger in SNL rats compared with normal ones, although the percentage increases from the baseline did not differ. The gabapentin-related ?2? ligand pregabalin increased extracellular glutamate concentration in the LC, whereas another ?2? ligand, 3-exo-aminobicyclo [2.2.1] heptane-2-exo-carboxylic acid (ABHCA), did not. Selective blockade by the dihydrokainic acid or knock-down of GLT-1 by the small interfering RNA abolished the gabapentin-induced glutamate increase in the LC, whereas blockade of GABA-B receptors by the CGP-35348 and depletion of noradrenalin by the dopamine-?-hydroxylase antibody conjugated to saporin did not. These results suggest that gabapentin induces glutamate release from astrocytes in the LC via GLT-1-dependent mechanisms to stimulate descending inhibition. The present study also demonstrates that this target of gabapentin in astrocytes does not require interaction with ?2? subunits in neurons. PMID:24495399

Suto, Takashi; Severino, Amie L; Eisenach, James C; Hayashida, Ken-ichiro

2014-06-01

267

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

PubMed

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

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

2009-01-01

268

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

269

Analyses of azimuthal seismic anisotrophy in the vertically fractured Spraberry and Dean formations, Midland County, Texas  

E-print Network

The configuration of a CDP gather from 3-D seismic reflection has source-receiver pairs located at different azimuths. This can be exploited to observe azimuthal variations of P- wave velocity related to azimuthal anisotropy in fractured media...

Sudarmo, Bernadus Supraptomo

1993-01-01

270

Arylsulfonylamino-benzanilides as inhibitors of the apical sodium-dependent bile salt transporter (SLC10A2).  

PubMed

The apical sodium-dependent bile salt transporter (ASBT) plays a pivotal role in maintaining bile acid homeostasis. Inhibition of ASBT would reduce bile acid pool size and lower cholesterol levels. In this report, a series of novel arylsulfonylaminobenzanilides were designed and synthesized as potential inhibitors of ASBT. Most of them demonstrated great potency against ASBT's bile acid transport activity. In particular, compound 5g? inhibited ASBT activity with an IC?? value of 0.11 ?M. These compounds represent potential cholesterol-lowering drugs. PMID:23752471

Liu, Hong-Tao; He, Hong-Wei; Bai, Xiao-Guang; Wang, Ju-Xian; Xu, Chang-Liang; Cai, Shi-Ying; Shao, Rong-Guang; Wang, Yu-Cheng

2013-01-01

271

ATP-dependent cadmium transport by the cadA cadmium resistance determinant in everted membrane vesicles of Bacillus subtilis.  

PubMed

Resistance to cadmium conferred by the staphylococcal plasmid pI258 occurs by means of energy-dependent efflux, resulting in decreased intracellular accumulation of cadmium. Recent sequence information suggested that efflux is mediated by a P-type ATPase. The cadA gene was previously expressed in Bacillus subtilis, conferring resistance to cadmium. Everted membrane vesicles were prepared from B. subtilis cells harboring either a plasmid containing the cadA system or the vector plasmid alone. 109Cd2+ transport into the everted membranes was measured in the presence of various energy sources. Cadmium transport was detected only in the presence of ATP as an energy source. The production of an electrochemical proton gradient (delta mu H+) by using NADH or phenazine methosulfate plus ascorbate was not able to drive transport. Reagents which dissipate delta pH abolished calcium transport due to the Ca2+/H+ antiporter but only partially inhibited cadmium transport. Inhibition of transport by the antibiotic bafilomycin A1 occurred at concentrations comparable to those which inhibit P-type ATPases. A band corresponding to the cadA gene product was identified on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and antibodies to the protein were prepared. PMID:1530844

Tsai, K J; Yoon, K P; Lynn, A R

1992-01-01

272

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; Verriès, Clotilde; Souquet, Jean-Marc; Mazauric, Jean-Paul; Klein, Markus; Cheynier, Véronique; Ageorges, Agnès

2009-01-01

273

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

274

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

PubMed Central

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 Ca2+ levels in a narrow concentration range. Dendritic transport of messenger RNAs that carry such GA motifs is inducible by influx of Ca2+ through voltage-dependent calcium channels upon ?-adrenergic receptor activation. The combined data establish a functional correspondence between Ca2+-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

2014-01-01

275

ATP-dependent transport of statins by human and rat MRP2/Mrp2  

SciTech Connect

Multidrug resistance associated protein-2, MRP2 (human), Mrp2 (rat) are an efflux transporter, responsible for the transport of numerous endogenous and xenobiotic compounds including taurocholate, methotrexate and carboxydichlorofluorescein (CDF). The present study aims to characterise transport of statins by human and rat MRP2/Mrp2 using membrane and vesicle preparations. All statins tested (simvastatin, pravastatin, pitavastatin, fluvastatin, atorvastatin, lovastatin and rosuvastatin) stimulated vanadate-sensitive ATPase activity in membranes expressing human or rat MRP2/Mrp2, suggesting that all statins are substrates of human and rat MRP2/Mrp2. The substrate affinity (Km) of all statins for MRP2/Mrp2 was comparable and no correlation between lipophilicity (logD{sub 7.0}) and Km was seen. All statins also inhibited uptake of the fluorescent Mrp2 substrate, CDF (1 ?M) into vesicles expressing human or rat MRP2/Mrp2 with similar IC{sub 50} values. Fitting of the inhibitory data to the hill slope equation, gave hill coefficients (h) of greater than one, suggesting that transport involved more than one binding site for inhibitors of MPR2 and Mrp2. We conclude that statins were transported by both human and rat MRP2/Mrp2 with similar affinity. Statins were also shown to compete with other substrates for transport by MRP2/Mrp2 and that this transport involved more than one binding site on the Mrp2/MRP2 protein. - Highlights: • We characterised MRP2 (human)/Mrp2 (rat)-mediated transport of statins. • We show statins were transported by human and rat MRP2/Mrp2. • Statins competed with a known substrate for transport by MRP2/Mrp2. • Competition involved more than one binding site on the MRP2/Mrp2 protein.

Ellis, Lucy C.J., E-mail: Luc_ellis@yahoo.co.uk [Section of Translational Medicine, Division of Applied Biology, Polwarth Building, Foresterhill, Aberdeen AB25 2ZD (United Kingdom); Hawksworth, Gabrielle M. [Section of Translational Medicine, Division of Applied Biology, Polwarth Building, Foresterhill, Aberdeen AB25 2ZD (United Kingdom); Weaver, Richard J. [Biologie Servier, Drug Safety Research Centre, 905 Route de Saran, 45520 Gidy (France)

2013-06-01

276

Sucrose- and H+-Dependent Charge Movements Associated with the Gating of Sucrose Transporter ZmSUT1  

PubMed Central

Background In contrast to man the majority of higher plants use sucrose as mobile carbohydrate. Accordingly proton-driven sucrose transporters are crucial for cell-to-cell and long-distance distribution within the plant body. Generally very negative plant membrane potentials and the ability to accumulate sucrose quantities of more than 1 M document that plants must have evolved transporters with unique structural and functional features. Methodology/Principal Findings To unravel the functional properties of one specific high capacity plasma membrane sucrose transporter in detail, we expressed the sucrose/H+ co-transporter from maize ZmSUT1 in Xenopus oocytes. Application of sucrose in an acidic pH environment elicited inward proton currents. Interestingly the sucrose-dependent H+ transport was associated with a decrease in membrane capacitance (Cm). In addition to sucrose Cm was modulated by the membrane potential and external protons. In order to explore the molecular mechanism underlying these Cm changes, presteady-state currents (Ipre) of ZmSUT1 transport were analyzed. Decay of Ipre could be best fitted by double exponentials. When plotted against the voltage the charge Q, associated to Ipre, was dependent on sucrose and protons. The mathematical derivative of the charge Q versus voltage was well in line with the observed Cm changes. Based on these parameters a turnover rate of 500 molecules sucrose/s was calculated. In contrast to gating currents of voltage dependent-potassium channels the analysis of ZmSUT1-derived presteady-state currents in the absence of sucrose (I?=?Q/?) was sufficient to predict ZmSUT1 transport-associated currents. Conclusions Taken together our results indicate that in the absence of sucrose, ‘trapped’ protons move back and forth between an outer and an inner site within the transmembrane domains of ZmSUT1. This movement of protons in the electric field of the membrane gives rise to the presteady-state currents and in turn to Cm changes. Upon application of external sucrose, protons can pass the membrane turning presteady-state into transport currents. PMID:20838661

Carpaneto, Armando; Koepsell, Hermann; Bamberg, Ernst; Hedrich, Rainer; Geiger, Dietmar

2010-01-01

277

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

278

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

PubMed

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

Wexler, Robert B; Sohlberg, Karl

2014-12-26

279

Dynamic control of auxin transport-dependent growth by AGCVIII protein kinases.  

PubMed

Recent years have seen important advances in understanding the Arabidopsis thaliana AGCVIII protein kinases D6 PROTEIN KINASE, PINOID/WAGs, and the phototropins. It has become apparent that these kinases control the distribution of the phytohormone auxin within the plant through phosphorylation of PIN-FORMED efflux carriers or of ABC transporters. Strikingly, D6PK and PID share the same phosphosites in PIN-FORMED proteins but have differential phosphosite preferences, which appear to control the activity and polar distribution of PIN-FORMED transporters. All three AGCVIII kinases are membrane-associated proteins that are dynamically transported to and from the plasma membrane. The implications of this dynamic transport for the activity and cell biological behavior of their phosphorylation substrates are just now starting to be understood. PMID:25305415

Barbosa, Inês Cr; Schwechheimer, Claus

2014-12-01

280

Protein kinase-A affects sorting and conformation of the sodium-dependent glucose co-transporter SGLT1.  

PubMed

In Chinese hamster ovary cells expressing rabbit sodium-dependent glucose transporter (rbSGLT1) protein kinase A (PKA) activators (forskolin and 8-Br-cAMP) stimulated alpha-methyl D-glucopyranoside uptake. Kinetic analysis revealed an increase in both V(max) and affinity of the transport. Immunohistochemistry and biotinylation experiments showed that this stimulation was accompanied by an increased amount of SGLT1 localized into the plasma membrane, which explains the higher V(max) of the transport. Cytochalasin D only partly attenuated the effect of forskolin as did deletion of the PKA phosphorylation site of SGLT1 in transient transfection studies. Experiments using an anti-phosphopeptide antibody revealed that forskolin also increased the extent of phosphorylation of SGLT1 in the membrane fraction. These results suggested that regulation of SGLT1 mediated glucose transport involves an additional direct effect on SGLT1 by phosphorylation. To evaluate this assumption further, phosphorylation studies of recombinant human SGLT1 (hSGLT1) in vitro were performed. In the presence of the catalytic subunit PKA and [(32)P] ATP 1.05 mol of phosphate were incorporated/mol of hSGLT1. Additionally, phosphorylated hSGLT1 demonstrated a reduction in tryptophan fluorescence intensity and a higher quenching by the hydrophilic Trp quencher acrylamide, particularly in the presence of D-glucose. These results indicate that PKA-mediated phosphorylation of SGLT1 changes the conformation of the empty carrier and the glucose carrier complex, probably causing the increase in transport affinity. Thus, PKA-mediated phosphorylation of the transporter represents a further mechanism in the regulation of SGLT1-mediated glucose transport in epithelial cells, in addition to a change in surface membrane expression. PMID:19115253

Subramanian, Supriya; Glitz, Petra; Kipp, Helmut; Kinne, Rolf K H; Castaneda, Francisco

2009-02-15

281

Modulation of high affinity ATP-dependent cyclic nucleotide transporters by specific and non-specific cyclic nucleotide phosphodiesterase inhibitors.  

PubMed

Intracellular cyclic nucleotides are eliminated by phosphodiesterases (PDEs) and by ATP Binding cassette transporters such as ABCC4 and ABCC5. PDE5 and ABCC5 have similar affinity for cGMP whereas ABCC5 has much higher affinity for cGMP compared with cAMP. Since the substrate (cGMP) is identical for these two eliminatory processes it is conceivable that various PDE inhibitors also modulate ABCC5-transport. Cyclic GMP is also transported by ABBC4 but the affinity is much lower with a Km 50-100 times higher than for that of ABBCC5. The present study aimed to determine Ki-values for specific or relative specific PDE5 inhibitors (vardenafil, tadalafil, zaprinast and dipyridamole) and the non-specific PDE inhibitors (IBMX, caffeine and theophylline) for ABCC5 and ABCC4 transport. The transport of [(3)H]-cGMP (2 µM) was concentration-dependently inhibited with the following Ki-values: vardenafil (0.62 µM), tadalafil (14.1 µM), zaprinast (0.68 µM) and dipyridamole (1.2 µM), IBMX (10 µM), caffeine (48 µM) and theophylline (69 µM). The Ki-values for the inhibition of the [(3)H]-cAMP (2 µM) transport were: vardenafil (3.4 µM), tadalafil (194 µM), zaprinast (2.8 µM), dipyridamole (5.5 µM), IBMX (16 µM), caffeine (41 µM) and theophylline (85 µM). The specificity for ABCC5 we defined as ratio between Ki-values for inhibition of [(3)H]-cGMP and [(3)H]-cAMP transport. Tadalafil showed the highest specificity (Ki-ratio: 0.073) and caffeine the lowest (Ki-ratio: 1.2). PMID:25445042

Aronsen, Lena; Orvoll, Elin; Lysaa, Roy; Ravna, Aina W; Sager, Georg

2014-12-15

282

Azimuthal distributions of charged hadrons, pions, and kaons produced in deep-inelastic scattering off unpolarized protons and deuterons  

NASA Astrophysics Data System (ADS)

The azimuthal cos?? and cos?2? modulations of the distribution of hadrons produced in unpolarized semi-inclusive deep-inelastic scattering of electrons and positrons off hydrogen and deuterium targets have been measured in the HERMES experiment. For the first time these modulations were determined in a four-dimensional kinematic space for positively and negatively charged pions and kaons separately, as well as for unidentified hadrons. These azimuthal dependences are sensitive to the transverse motion and polarization of the quarks within the nucleon via, e.g., the Cahn, Boer-Mulders and Collins effects.

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

2013-01-01

283

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

E-print Network

Spin-averaged asymmetries in the azimuthal distributions of positive and negative hadrons produced in deep inelastic scattering were measured using the CERN SPS muon beam at $160$ GeV/c and a $^6$LiD target. The amplitudes of the three azimuthal modulations $\\cos\\phi_h$, $\\cos2\\phi_h$ and $\\sin\\phi_h$ were obtained binning the data separately in each of the relevant kinematic variables $x$, $z$ or $p_T^{\\,h}$ and binning in a three-dimensional grid of these three variables. The amplitudes of the $\\cos \\phi_h$ and $\\cos 2\\phi_h$ modulations show strong kinematic dependencies both for positive and negative hadrons.

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

2014-01-24

284

Influence of azimuthal variations in the jovian magnetospheric field on global thermospheric energy inputs  

NASA Astrophysics Data System (ADS)

Jupiter's upper atmosphere is coupled to the magnetosphere via an electrical circuit in which current travels along the planetary magnetic field between these two regions, radially outwards in the magnetospheric equatorial plane, and equatorward through the ionosphere. Energy and momentum are communicated to the thermosphere by a combination of joule heating and ion drag. Together, these processes modify the local thermosphere, and produce a system of meridional and azimuthal winds, as well as localized heating. The driver for this current circuit is the radial transport of plasma outward through the planetary magnetosphere. Io ejects ~1000 kg/s neutral material, which then becomes partly ionized through electron impact and charge exchange, leaving ~500 kg/s plasma to be transported through the magnetosphere. As the remaining plasma moves outwards, it slows in its rotation to conserve angular momentum, bending back the planetary magnetic field lines that thread it. Field-aligned currents simultaneously develop to support this magnetic geometry, transporting angular momentum from the planet to the magnetospheric plasma. In the equatorial plane, a j x B force accelerates the plasma towards corotation with the planet. Axially symmetric models for the magnetic field and plasmasheet have been extensively applied to describe this process. Outside of ~20 RJ (jovian radii), however, the north-south component of the equatorial magnetic field varies significantly with azimuth (local time). Therefore, the magnitude of the current is also expected to change, in accordance with the corresponding variation in the radial profile of magnetospheric plasma angular velocity. Using the UCL JASMIN model, which describes the coupled thermosphere-ionosphere-magnetosphere system in 2.5 dimensions, we explore how these azimuthal variations in the equatorial magnetic field structure modify the ionospheric currents, and discuss the ensuing effects on the thermospheric heating and flows.

Ray, L. C.; Achilleos, N.; Yates, J. N.; Vogt, M. F.

2013-09-01

285

14 CFR 171.313 - Azimuth performance requirements.  

Code of Federal Regulations, 2013 CFR

...NAVIGATIONAL FACILITIES NON-FEDERAL NAVIGATION FACILITIES Microwave Landing System (MLS) § 171.313 Azimuth performance... Includes errors due to ground and airborne equipment and propagation effects. 2 The system PFN component must not...

2013-01-01

286

14 CFR 171.313 - Azimuth performance requirements.  

Code of Federal Regulations, 2010 CFR

...NAVIGATIONAL FACILITIES NON-FEDERAL NAVIGATION FACILITIES Microwave Landing System (MLS) § 171.313 Azimuth performance... Includes errors due to ground and airborne equipment and propagation effects. 2 The system PFN component must not...

2010-01-01

287

14 CFR 171.313 - Azimuth performance requirements.  

Code of Federal Regulations, 2014 CFR

...NAVIGATIONAL FACILITIES NON-FEDERAL NAVIGATION FACILITIES Microwave Landing System (MLS) § 171.313 Azimuth performance... Includes errors due to ground and airborne equipment and propagation effects. 2 The system PFN component must not...

2014-01-01

288

14 CFR 171.313 - Azimuth performance requirements.  

Code of Federal Regulations, 2011 CFR

...NAVIGATIONAL FACILITIES NON-FEDERAL NAVIGATION FACILITIES Microwave Landing System (MLS) § 171.313 Azimuth performance... Includes errors due to ground and airborne equipment and propagation effects. 2 The system PFN component must not...

2011-01-01

289

14 CFR 171.313 - Azimuth performance requirements.  

Code of Federal Regulations, 2012 CFR

...NAVIGATIONAL FACILITIES NON-FEDERAL NAVIGATION FACILITIES Microwave Landing System (MLS) § 171.313 Azimuth performance... Includes errors due to ground and airborne equipment and propagation effects. 2 The system PFN component must not...

2012-01-01

290

Syntaxin 5-Dependent Retrograde Transport to the Golgi is Required for AAV Transduction.  

PubMed

Intracellular transport of recombinant Adeno-associated virus (AAV) is still incompletely understood. In particular, the trafficking steps preceding the release of incoming AAV particles from the endosomal system into the cytoplasm-allowing subsequent nuclear import and the initiation of gene expression-remain to be elucidated fully. Others and we previously showed that a significant proportion of viral particles are transported to the Golgi apparatus, and that Golgi disruption caused by the drug brefeldin A efficiently blocks AAV2 transduction. However, because brefeldin A is known to exert pleiotropic effects on the entire endosomal system, the functional relevance of Golgi transport for AAV transduction remains to be established definitively. Here, we show that AAV2 trafficking toward the trans-Golgi network (TGN) and the Golgi apparatus correlates with transduction efficiency and relies on a non-classical retrograde transport pathway that is independent of retromer, late endosomes and recycling endosomes. AAV2 transduction is unaffected by knock-down of syntaxins 6 and 16, which are two major effectors in the retrograde transport of both exogenous and endogenous cargo. On the other hand, inhibition of syntaxin 5 function by siRNA silencing or treatment with Retro-2cycl strongly decrease AAV2 transduction and Golgi transport. This inhibition of transduction is observed with several AAV serotypes and a number of primary and immortalized cells. Together, our data strongly suggest that syntaxin 5-mediated retrograde transport to the Golgi is a broadly conserved feature of AAV trafficking that appears to be independent of the identity of the receptors used for viral attachment. PMID:25410859

Nonnenmacher, Mathieu E; Cintrat, Jean-Christophe; Gillet, Daniel; Weber, Thomas

2014-11-19

291

Azimuthal structure in wire-array Z pinch experiments  

Microsoft Academic Search

Nested wire-array loads on Z with a high degree of azimuthal symmetry in the outside current-return-shell (which surrounds a z pinch) exhibit a 6±2 azimuthal mode structure in the axial X-ray emission near stagnation when the pinch is viewed from above through a small radiation-exit-hole in the anode. MACH3 numerical simulations show that if a low-number mode like 6 does

Thomas W. L. Sanford; Norman F. Roderick; Raymond C. Mock; Kenneth W. Struve; Darrell L. Peterson

2002-01-01

292

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

293

Substrate-dependent expression of Na+ transport and shunt conductance in A6 epithelia.  

PubMed

A6 epithelia grown in tissue culture vary enormously in their baseline rates of Na+ transport due to differences in growth media, serum, and other unknown factors. To evaluate the effect(s) of substrates on expression of Na+ transport, we determined short-circuit currents, open-circuit voltages, and electrical resistances of mature confluent A6 epithelia grown on a variety of commercially available permeable supports. Because the cells, growth conditions, and all other factors were the same, differences in transport could be attributed alone to the substrate on which the cells were grown. Tissues were grown on both large- and small-diameter inserts of the same type with differing ratios of edge length to area so that the contribution of the edge and tight junction conductances to the combined shunt conductance of the inserts could be evaluated. Shunt and cellular conductances and the cellular Thévenin electromotive force were determined after aldosterone stimulation and amiloride inhibition of Na+ transport. Marked and extreme differences were observed not only for expression of Na+ transport (controls, 0.09-3.94 microA/cm2; aldosterone, 1.53-28.2 microA/cm2) due to changes of apical membrane conductance but also for the development of junctional conductances (3,250 to < infinity omega.cm2) and edge conductances (13,175 to < infinity omega.cm) among substrates. PMID:9277341

Helman, S I; Liu, X

1997-08-01

294

Fluoride-dependent interruption of the transport cycle of a CLC Cl?/H+ antiporter  

PubMed Central

Cl?/H+ antiporters of the CLC superfamily transport anions across biological membranes in varied physiological contexts. These proteins are weakly selective among anions commonly studied, including Cl?, Br?, I?,NO3?, and SCN?, but appear to be very selective against F?. The recent discovery of a new CLC clade of F?/H+ antiporters, which are highly selective for F? over Cl?, led us to investigate the mechanism of Cl?-over-F? selectivity by a CLC Cl?/H+ antiporter, CLC-ec1. By subjecting purified CLC-ec1 to anion transport measurements, electrophysiological recording, equilibrium ligand-binding studies, and x-ray crystallography, we show that F? binds in the Cl? transport pathway with affinity similar to Cl?, but stalls the transport cycle. Examination of various mutant antiporters implies a “lock-down” mechanism of F? inhibition, in which F?, by virtue of its unique H-bonding chemistry, greatly retards a proton-linked conformational change essential for the transport cycle of CLC-ec1. PMID:24036509

Lim, Hyun-Ho; Stockbridge, Randy B.; Miller, Christopher

2013-01-01

295

Combined effect of promoter polymorphisms in the dopamine D4 receptor and the serotonin transporter genes in heroin dependence.  

PubMed

Dopamine D4 receptor (DRD4) and serotonin transporter (SERT) gene polymorphisms were studied, as possible genetic risk factors for substance dependence. The case-control study involved a large cohort (n = 362) of healthy Caucasian population, and an initial sample of 73 substance dependent patients (including a subgroup of 53 heroin dependents). Improved methods were applied for genotype detection of the DRD4 polymorphisms (exon 3 48 bp VNTR; -521 C/T SNP and 120 bp duplication in the 5' flanking region) and the SERT gene polymorphisms (5-hydroxytriptamin transporter linked polymorphic region [5-HTTLPR] in the 5' flanking region and the intron 2 VNTR [STin2]). Association between the -521 C/T SNP of the DRD4 promoter region and substance dependence was significant in the subgroup of heroin dependents (p = 0.044). The other analyzed polymorphisms did not show any significant association, but an interaction between -521 C/T SNP of DRD4 and the 5-HTTLPR polymorphisms was observed. Association between the -521 CC vs. CT or TT genotypes and heroin dependence was enhanced in the presence of short (s or 14-repeat) 5-HTTLPR allele (p 0.01). The odds ratio of 2.14 observed for the -521 CC genotype increased to 4.82 in double homozygotes of -521 CC and 5-HTTLPR ss, emphasizing the importance of combined analysis of polymorphisms in the dopaminergic and serotonergic systems in heroin dependence. However, due to the limited size of our sample these results should be interpreted with caution. PMID:16167465

Szilagyi, Agnes; Boór, Krisztina; Székely, Anna; Gaszner, Péter; Kalász, Huba; Sasvári-Székely, Mária; Barta, Csaba

2005-03-01

296

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

PubMed Central

Anion and fluid secretion are both defective in cystic fibrosis (CF); however, the transport mechanisms are not well understood. In this study, Cl? and HCO3? secretion was measured using genetically matched CF transmembrane conductance regulator (CFTR)-deficient and CFTR-expressing cell lines derived from the human airway epithelial cell line Calu-3. Forskolin stimulated the short-circuit current (Isc) across voltage-clamped monolayers, and also increased the equivalent short-circuit current (Ieq) calculated under open-circuit conditions. Isc was equivalent to the HCO3? net flux measured using the pH-stat technique, whereas Ieq was the sum of the Cl? and HCO3? net fluxes. Ieq and HCO3? fluxes were increased by bafilomycin and ZnCl2, suggesting that some secreted HCO3? is neutralized by parallel electrogenic H+ secretion. Ieq and fluid secretion were dependent on the presence of both Na+ and HCO3?. The carbonic anhydrase inhibitor acetazolamide abolished forskolin stimulation of Ieq and HCO3? secretion, suggesting that HCO3? transport under these conditions requires catalysed synthesis of carbonic acid. Cl? was the predominant anion in secretions under all conditions studied and thus drives most of the fluid transport. Nevertheless, 50–70% of Cl? and fluid transport was bumetanide-insensitive, suggesting basolateral Cl? loading by a sodium–potassium–chloride cotransporter 1 (NKCC1)-independent mechanism. Imposing a transepithelial HCO3? gradient across basolaterally permeabilized Calu-3 cells sustained a forskolin-stimulated current, which was sensitive to CFTR inhibitors and drastically reduced in CFTR-deficient cells. Net HCO3? secretion was increased by bilateral Cl? removal and therefore did not require apical Cl?/HCO3? exchange. The results suggest a model in which most HCO3? is recycled basolaterally by exchange with Cl?, and the resulting HCO3?-dependent Cl? transport provides an osmotic driving force for fluid secretion. PMID:22777674

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

2012-01-01

297

Commensurability-Dependent Transport of a Wigner Crystal in a Nanoconstriction  

NASA Astrophysics Data System (ADS)

We present the first transport measurements of a classical Wigner crystal through a constriction formed by a split-gate electrode. The Wigner crystal is formed on the surface of superfluid helium confined in a microchannel. At low temperatures, the current is periodically suppressed with increasing split-gate voltage, resulting in peaklike transport features. We also present the results of molecular dynamics simulations that reproduce this phenomenon. We demonstrate that, at the split-gate voltages for which the current is suppressed, the electron lattice is arranged such that the stability of particle positions against thermal fluctuations is enhanced. In these configurations, the suppression of transport due to interelectron Coulomb forces becomes important.

Rees, D. G.; Totsuji, H.; Kono, K.

2012-04-01

298

Characterization, cDNA cloning, and functional expression of mouse ileal sodium-dependent bile acid transporter.  

PubMed

Mouse ileal sodium dependent bile acid transporter (ISBT) was characterized using isolated enterocytes. Only enterocytes from the most distal portion showed Na+-dependent [3H]taurocholate uptake. Northern blot analysis using a probe against mouse ISBT revealed the expression of mouse ISBT mRNA to be restricted to the distal ileum. The Km and Vmax for Na+-dependent [3H]taurocholate transport into isolated ileocytes were calculated as 27 microM and 360 pmol/mg protein/min, respectively. Uptake of [3H]taurocholate was inhibited by N-ethylmaleimide. We have cloned ISBT cDNA from mouse ileum. The cDNA included the entire open reading frame coding 348 amino acid protein with seven hydrophobic segments and two N-glycosylation sites. COS-7 cells transfected with the expression vector containing this cDNA expressed Na+-dependent [3H]taurocholate uptake activity with a Km of 34 microM. PMID:10101301

Saeki, T; Matoba, K; Furukawa, H; Kirifuji, K; Kanamoto, R; Iwami, K

1999-04-01

299

Regulation of rat intestinal Na-dependent phosphate transporters by dietary phosphate  

PubMed Central

Hyperphosphatemia associated with chronic kidney disease is one of the factors that can promote vascular calcification, and intestinal Pi absorption is one of the pharmacological targets that prevents it. The type II Na-Pi cotransporter NaPi-2b is the major transporter that mediates Pi reabsorption in the intestine. The potential role and regulation of other Na-Pi transporters remain unknown. We have identified expression of the type III Na-Pi cotransporter PiT-1 in the apical membrane of enterocytes. Na-Pi transport activity and NaPi-2b and PiT-1 proteins are mostly expressed in the duodenum and jejunum of rat small intestine; their expression is negligible in the ileum. In response to a chronic low-Pi diet, there is an adaptive response restricted to the jejunum, with increased brush border membrane (BBM) Na-Pi transport activity and NaPi-2b, but not PiT-1, protein and mRNA abundance. However, in rats acutely switched from a low- to a high-Pi diet, there is an increase in BBM Na-Pi transport activity in the duodenum that is associated with an increase in BBM NaPi-2b protein abundance. Acute adaptive upregulation is restricted to the duodenum and induces an increase in serum Pi that produces a transient postprandial hyperphosphatemia. Our study, therefore, indicates that Na-Pi transport activity and NaPi-2b protein expression are differentially regulated in the duodenum vs. the jejunum and that postprandial upregulation of NaPi-2b could be a potential target for treatment of hyperphosphatemia. PMID:19675183

Caldas, Yupanqui; Sutherland, Eileen; Wilson, Paul; Breusegem, Sophia; Barry, Nicholas; Blaine, Judith; Jiang, Tao; Wang, Xiaoxin X.; Levi, Moshe

2009-01-01

300

ANIT-Induced Intrahepatic Cholestasis Alters Hepatobiliary Transporter Expression via Nrf2-Dependent and Independent Signaling  

PubMed Central

Alpha-naphthylisothiocyanate (ANIT) causes intrahepatic cholestasis by injuring biliary epithelial cells. Adaptive regulation of hepatobiliary transporter expression has been proposed to reduce liver injury during cholestasis. Recently, the oxidative stress transcription factor Nrf2 (nf-e2–related factor 2) was shown to regulate expression of hepatobiliary transporters. The purpose of this study was to determine whether ANIT-induced hepatotoxicity and regulation of hepatobiliary transporters are altered in the absence of Nrf2. For this purpose, wild-type and Nrf2-null mice were administered ANIT (75 mg/kg po). Surprisingly, ANIT-induced hepatotoxicity was similar in both genotypes at 48 h. Accumulation of bile acids in serum and liver was lower in Nrf2-null mice compared with wild-types treated with ANIT. Transporter mRNA profiles differed between wild-type and Nrf2-null mice after ANIT. Bsep (bile salt export pump), Mdr2 (multidrug resistance gene), and Mrp3 (multidrug resistance–associated protein) efflux transporters were increased by ANIT in wild-type, but not in Nrf2-null mice. In contrast, mRNA expression of two hepatic uptake transporters, Ntcp (sodium-taurocholate cotransporting polypeptide) and Oatp1b2 (organic anion transporting peptide), were decreased in both genotypes after ANIT, with larger declines in Nrf2-null mice. mRNA expression of the transcriptional repressor of Ntcp, small heterodimeric partner (SHP), was increased in Nrf2-null mice after ANIT. Furthermore, hepatocyte nuclear factor 1? (HNF1?), which regulates Oatp1b2, was downregulated in ANIT-treated Nrf2-null mice. Preferential upregulation of SHP and downregulation of HNF1? and uptake transporters likely explains why Nrf2-null mice exhibited similar injury to wild-types after ANIT. A subsequent study revealed that treatment of mice with the Nrf2 activator oltipraz protects against ANIT-induced histological injury. Despite compensatory changes in Nrf2-null mice to limit ANIT toxicity, pharmacological activation of Nrf2 may represent a therapeutic option for intrahepatic cholestasis. PMID:19181614

Tanaka, Yuji; Aleksunes, Lauren M.; Cui, Yue Julia; Klaassen, Curtis D.

2009-01-01

301

Horizontal Contraction of Oceanic Lithosphere Tested Using Azimuths of Transform Faults  

NASA Astrophysics Data System (ADS)

A central hypothesis or approximation of plate tectonics is that the plates are rigid, which implies that oceanic lithosphere does not contract horizontally as it cools (hereinafter "no contraction"). An alternative hypothesis is that vertically averaged tensional thermal stress in the competent lithosphere is fully relieved by horizontal thermal contraction (hereinafter "full contraction"). These two hypotheses predict different azimuths for transform faults. We build on prior predictions of horizontal thermal contraction of oceanic lithosphere as a function of age to predict the bias induced in transform-fault azimuths by full contraction for 140 azimuths of transform faults that are globally distributed between 15 plate pairs. Predicted bias increases with the length of adjacent segments of mid-ocean ridges and depends on whether the adjacent ridges are stepped, crenellated, or a combination of the two. All else being equal, the bias decreases with the length of a transform fault and modestly decreases with increasing spreading rate. The value of the bias varies along a transform fault. To correct the observed transform-fault azimuths for the biases, we average the predicted values over the insonified portions of each transform fault. We find the bias to be as large as 2.5°, but more typically is ? 1.0°. We test whether correcting for the predicted biases improves the fit to plate motion data. To do so, we determine the sum-squared normalized misfit for various values of ?, which we define to be the fractional multiple of bias predicted for full contraction. ? = 1 corresponds to the full contraction, while ? = 0 corresponds to no contraction. We find that the minimum in sum-squared normalized misfit is obtained for ? = 0.9 ±0.4 (95% confidence limits), which excludes the hypothesis of no contraction, but is consistent with the hypothesis of full contraction. Application of the correction reduces but does not eliminate the longstanding misfit between the azimuth of the Kane transform fault with respect to those of the other North America-Nubia transform faults. We conclude that significant ridge-parallel horizontal thermal contraction occurs in young oceanic lithosphere and that it is accommodated by widening of transform-fault valleys, which causes biases in transform-fault azimuths up to 2.5°.

Gordon, R. G.; Mishra, J. K.

2012-12-01

302

Azimuthal asymmetries in $p^\\uparrow p \\to {\\rm jet}\\, ?\\, X$  

E-print Network

We study the azimuthal asymmetries for the distributions of leading pions inside a jet produced inclusively in high-energy proton-proton collisions within the framework of the transverse momentum dependent generalized parton model. We present results for the RHIC center-of-mass energies $\\sqrt{s}$ = 200 and 500 GeV, mainly for forward jet rapidities, in particular for the two mechanisms which dominate such asymmetries: the Sivers and the Collins effects. We also briefly discuss the case of inclusive jet production and, adopting the so-called colour gauge invariant parton model, we propose a phenomenological analysis of the process dependence of the quark Sivers function.

Cristian Pisano; Umberto D'Alesio; Francesco Murgia

2014-12-15

303

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

304

Transport anomalies and adaptative pressure-dependent topological constraints in tetrahedral liquids: evidence for a reversibility window analogue.  

PubMed

Topological rigid constraints can be computed rather simply with changing composition and temperature but their estimation remains challenging for other thermodynamic variables. Here, the investigation of densified silicate liquids from molecular dynamics simulations combined with an analysis of radial and angular atomic excursions allows defining a pressure dependence of such constraints. Results show, that for a given composition, the dependence is nonmonotonic as it depends on the interplay between constraints broken by thermal activation and additional constraints arising from the increase of network connectivity under pressure. An anomalous behavior for oxygen bending constraints is obtained in the (P, T) map which connects to reported anomalies in transport properties and is identified as the pressure analogue of the stress-free Boolchand intermediate phase in rigidity driven by composition. PMID:23496720

Bauchy, M; Micoulaut, M

2013-03-01

305

Calcium/Calmodulin-Dependent Kinase II Regulates the Interaction between the Serotonin Transporter and Syntaxin 1A  

PubMed Central

Summary Plasma membrane serotonin transporters (SERTs) regulate serotonin (5HT) levels in brain and are a site of action of antidepressants and psychostimulant drugs of abuse. Syntaxin 1A is a component of the synaptic vesicle docking and fusion apparatus and has been shown to interact with multiple plasma membrane neurotransmitter transporters including SERT. Previously we showed that syntaxin 1A regulates the transport stoichiometry of SERT. When not bound to syntaxin 1A, SERT shows both substrate-independent Na+ fluxes and substrate-dependent Na+ fluxes of variable stoichiometry; these fluxes are eliminated in the presence of syntaxin 1A as Na+ flux becomes strictly coupled to 5HT uptake. However, not known are the endogenous signaling molecules that determine the conducting states that SERT exhibits. In the present experiments, we show that inhibitors of calcium/calmodulin-dependent kinase II (CaM kinase II) modulate the stoichiometry of 5HT flux and that this effect requires syntaxin 1A. The modulation correlates with a shift in the affinity of SERT for syntaxin 1A binding. The regulation by CaM kinase II is eliminated by a mutation in the N-terminal domain of SERT. In neonatal thalomocortical neurons that endogenously express SERT and syntaxin 1A, inhibition of CaM kinase II reveals SERT-mediated currents. These data suggest that calcium-mediated signals can serve as a trigger for regulating protein-protein interactions that control SERT conducting states. PMID:18602929

Ciccone, Marcia A.; Timmons, Miranda; Phillips, Anthony; Quick, Michael W.

2008-01-01

306

Carboxypeptidase E cytoplasmic tail-driven vesicle transport is key for activity-dependent secretion of peptide hormones.  

PubMed

Vesicular transport of peptide hormones from the cell body to the plasma membrane for activity-dependent secretion is important for endocrine function, but how it is achieved is unclear. Here we uncover a mechanism in which the cytoplasmic tail of transmembrane carboxypeptidase E (CPE) found in proopiomelanocotin (POMC)/ACTH vesicles interacts with microtubule-based motors to control transport of these vesicles to the release site in pituitary cells. Overexpression of the CPE tail in live cells significantly reduced the velocity and distance of POMC/ACTH- and CPE-containing vesicle movement into the cell processes. Biochemical studies showed that the CPE tail interacted with dynactin, which, in turn, recruited microtubule plus-end motors kinesin 2 and kinesin 3. Overexpression of the CPE tail inhibited the stimulated secretion of ACTH from AtT20 cells. Thus, the CPE cytoplasmic tail interaction with dynactin-kinesin 2/kinesin 3 plays an important role in the transport of POMC vesicles for activity-dependent secretion. PMID:18202146

Park, Joshua J; Cawley, Niamh X; Loh, Y Peng

2008-04-01

307

Hydrogen sulfide modulates actin-dependent auxin transport via regulating ABPs results in changing of root development in Arabidopsis.  

PubMed

Hydrogen sulfide (H2S) signaling has been considered a key regulator of plant developmental processes and defenses. In this study, we demonstrate that high levels of H2S inhibit auxin transport and lead to alterations in root system development. H2S inhibits auxin transport by altering the polar subcellular distribution of PIN proteins. The vesicle trafficking and distribution of the PIN proteins are an actin-dependent process. H2S changes the expression of several actin-binding proteins (ABPs) and decreases the occupancy percentage of F-actin bundles in the Arabidopsis roots. We observed the effects of H2S on F-actin in T-DNA insertion mutants of cpa, cpb and prf3, indicating that the effects of H2S on F-actin are partially removed in the mutant plants. Thus, these data imply that the ABPs act as downstream effectors of the H2S signal and thereby regulate the assembly and depolymerization of F-actin in root cells. Taken together, our data suggest that the existence of a tightly regulated intertwined signaling network between auxin, H2S and actin that controls root system development. In the proposed process, H2S plays an important role in modulating auxin transport by an actin-dependent method, which results in alterations in root development in Arabidopsis. PMID:25652660

Jia, Honglei; Hu, Yanfeng; Fan, Tingting; Li, Jisheng

2015-01-01

308

Hydrogen sulfide modulates actin-dependent auxin transport via regulating ABPs results in changing of root development in Arabidopsis  

PubMed Central

Hydrogen sulfide (H2S) signaling has been considered a key regulator of plant developmental processes and defenses. In this study, we demonstrate that high levels of H2S inhibit auxin transport and lead to alterations in root system development. H2S inhibits auxin transport by altering the polar subcellular distribution of PIN proteins. The vesicle trafficking and distribution of the PIN proteins are an actin-dependent process. H2S changes the expression of several actin-binding proteins (ABPs) and decreases the occupancy percentage of F-actin bundles in the Arabidopsis roots. We observed the effects of H2S on F-actin in T-DNA insertion mutants of cpa, cpb and prf3, indicating that the effects of H2S on F-actin are partially removed in the mutant plants. Thus, these data imply that the ABPs act as downstream effectors of the H2S signal and thereby regulate the assembly and depolymerization of F-actin in root cells. Taken together, our data suggest that the existence of a tightly regulated intertwined signaling network between auxin, H2S and actin that controls root system development. In the proposed process, H2S plays an important role in modulating auxin transport by an actin-dependent method, which results in alterations in root development in Arabidopsis. PMID:25652660

Jia, Honglei; Hu, Yanfeng; Fan, Tingting; Li, Jisheng

2015-01-01

309

Monosaccharide Absorption Activity of Arabidopsis Roots Depends on Expression Profiles of Transporter Genes under High Salinity Conditions*  

PubMed Central

Plant roots are able to absorb sugars from the rhizosphere but also release sugars and other metabolites that are critical for growth and environmental signaling. Reabsorption of released sugar molecules could help reduce the loss of photosynthetically fixed carbon through the roots. Although biochemical analyses have revealed monosaccharide uptake mechanisms in roots, the transporters that are involved in this process have not yet been fully characterized. In the present study we demonstrate that Arabidopsis STP1 and STP13 play important roles in roots during the absorption of monosaccharides from the rhizosphere. Among 14 STP transporter genes, we found that STP1 had the highest transcript level and that STP1 was a major contributor for monosaccharide uptake under normal conditions. In contrast, STP13 was found to be induced by abiotic stress, with low expression under normal conditions. We analyzed the role of STP13 in roots under high salinity conditions where membranes of the epidermal cells were damaged, and we detected an increase in the amount of STP13-dependent glucose uptake. Furthermore, the amount of glucose efflux from stp13 mutants was higher than that from wild type plants under high salinity conditions. These results indicate that STP13 can reabsorb the monosaccharides that are released by damaged cells under high salinity conditions. Overall, our data indicate that sugar uptake capacity in Arabidopsis roots changes in response to environmental stresses and that this activity is dependent on the expression pattern of sugar transporters. PMID:22041897

Yamada, Kohji; Kanai, Motoki; Osakabe, Yuriko; Ohiraki, Haruka; Shinozaki, Kazuo; Yamaguchi-Shinozaki, Kazuko

2011-01-01

310

A novel method to quantify H +-ATPase-dependent Na + transport across plasma membrane vesicles  

Microsoft Academic Search

To prevent sodium toxicity in plants, Na+ is excluded from the cytosol to the apoplast or the vacuole by Na+\\/H+ antiporters. The secondary active transport of Na+ to apoplast against its electrochemical gradient is driven by plasma membrane H+-ATPases that hydrolyze ATP and pump H+ across the plasma membrane. Current methods to determine Na+ flux rely either on the use

Yongqing Yang; Lei Hu; Xuemei Chen; Eric A. Ottow; Andrea Polle; Xiangning Jiang

2007-01-01

311

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

E-print Network

-glucuronide by OATP1B3, whereas it inhibits transport of 14 Table 1-2: Selected Substrates of OATP1A2. Modified from Roth et al. (Submitted). Substrates References Acebutolol (Kato et al., 2009) Atenolol (Kato et al., 2009) Atrasentan (Katz et...

Roth, Megan Elizabeth

2011-12-31

312

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

Microsoft Academic Search

Tritium transport in edge localized mode (ELM) high confinement (H-mode) plasmas is analyzed here as a function of density for discharges from the recent trace tritium experimental campaign performed on Joint European Torus. In this campaign small amounts of tritium have been puffed or injected (with neutral beam injectors) into deuterium plasmas [K.-D. Zastrow, J. M. Adams, Yu. Baranov et

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

2005-01-01

313

Deformationally dependent fluid transport properties of porcine coronary arteries based on location in the coronary vasculature  

PubMed Central

Objective Understanding coronary artery mass transport allows researchers to better comprehend how drugs or proteins move through, and deposit into, the arterial wall. Characterizing how the convective component of transport changes based on arterial location could be useful to better understand how molecules distribute in different locations in the coronary vasculature. Methods and results We measured the mechanical properties and wall fluid flux transport properties of de-endothelialized (similar to post-stenting or angioplasty) left anterior descending (LADC) and right (RC) porcine coronary arteries along their arterial lengths. Multiphoton microscopy was used to determine microstructural differences. Proximal LADC regions had a higher circumferential stiffness than all other regions. Permeability decreased by 198% in the LADC distal region compared to other LADC regions. The RC artery showed a decrease of 46.9% from the proximal to middle region, and 51.7% from the middle to distal regions. The porosity increased in the intima between pressure states, without differences through the remainder of the arterial thickness. Conclusions We showed that the permeabilities and mechanical properties do vary in the coronary vasculature. With variations in mechanical properties, overexpansion of stents can occur more easily while variations in permeability may lead to altered transport based on location. PMID:23127633

Keyes, Joseph T.; Lockwood, Danielle R.; Simon, Bruce R.; Vande Geest, Jonathan P.

2013-01-01

314

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...

315

Dimensionality-dependent charge transport in close-packed nanoparticle arrays: from 2D to 3D.  

PubMed

Charge transport properties in close-packed nanoparticle arrays with thickness crossing over from two dimensions to three dimensions have been studied. The dimensionality transition of nanoparticle arrays was realized by continually printing spatially well-defined nanoparticle monolayers on top of the device in situ. The evolution of charge transport properties depending on the dimensionality has been investigated in both the Efros-Shaklovskii variable-range-hopping (ES-VRH) (low temperature) regime and the sequential hopping (SH) (medium temperature) regime. We find that the energy barriers to transport decrease when the thickness of nanoparticle arrays increases from monolayer to multilayers, but start to level off at the thickness of 4-5 monolayers. The energy barriers are characterized by the coefficient ?D at ES-VRH regime and the activation energy Ea at SH regime. Moreover, a turning point for the temperature coefficient of conductance was observed in multilayer nanoparticle arrays at high temperature, which is attributed to the increasing mobility with decreasing temperature of hopping transport in three dimensions. PMID:25523836

Wang, Ying; Duan, Chao; Peng, Lianmao; Liao, Jianhui

2014-01-01

316

Dimensionality-dependent charge transport in close-packed nanoparticle arrays: from 2D to 3D  

NASA Astrophysics Data System (ADS)

Charge transport properties in close-packed nanoparticle arrays with thickness crossing over from two dimensions to three dimensions have been studied. The dimensionality transition of nanoparticle arrays was realized by continually printing spatially well-defined nanoparticle monolayers on top of the device in situ. The evolution of charge transport properties depending on the dimensionality has been investigated in both the Efros-Shaklovskii variable-range-hopping (ES-VRH) (low temperature) regime and the sequential hopping (SH) (medium temperature) regime. We find that the energy barriers to transport decrease when the thickness of nanoparticle arrays increases from monolayer to multilayers, but start to level off at the thickness of 4-5 monolayers. The energy barriers are characterized by the coefficient ?D at ES-VRH regime and the activation energy Ea at SH regime. Moreover, a turning point for the temperature coefficient of conductance was observed in multilayer nanoparticle arrays at high temperature, which is attributed to the increasing mobility with decreasing temperature of hopping transport in three dimensions.

Wang, Ying; Duan, Chao; Peng, Lianmao; Liao, Jianhui

2014-12-01

317

Overexpression of specific proton motive force-dependent transporters facilitate the export of surfactin in Bacillus subtilis.  

PubMed

A novel surfactin producer, Bacillus subtilis THY-7, was isolated from soil. Using liposomes and transmembrane transport inhibitors, the surfactin efflux in THY-7 was determined to be mainly dependent on proton motive force (PMF), not ATP hydrolysis. YcxA, KrsE and YerP, three putative lipopeptide transporters with PMF as energy source, were then highlighted in this work. A mutant YcxA named as YcxAmt, with 2 transmembrane helices deletion due to a code-shift mutation of the encoding gene, was identified in THY-7. This truncated YcxAmt was confirmed unable to transfer surfactin; on the contrary, overexpression of the natural full-lengthYcxA enhanced the secretion of surfactin by 89 %. KrsE, a putative kurstakin transporter, was found also capable of transporting surfactin. Overexpression of KrsE increased the production of surfactin by 52 %. In the culture of YerP-overexpressing strain at 24 h, surfactin titer reached 1.58 g L(-1), which was 145 % higher than that of the control. This indicated that YerP acted as the major surfactin exporter in B. subtilis THY-7. PMID:25366377

Li, Xu; Yang, Huan; Zhang, Donglai; Li, Xue; Yu, Huimin; Shen, Zhongyao

2015-01-01

318

Dimensionality-dependent charge transport in close-packed nanoparticle arrays: from 2D to 3D  

PubMed Central

Charge transport properties in close-packed nanoparticle arrays with thickness crossing over from two dimensions to three dimensions have been studied. The dimensionality transition of nanoparticle arrays was realized by continually printing spatially well-defined nanoparticle monolayers on top of the device in situ. The evolution of charge transport properties depending on the dimensionality has been investigated in both the Efros-Shaklovskii variable-range-hopping (ES-VRH) (low temperature) regime and the sequential hopping (SH) (medium temperature) regime. We find that the energy barriers to transport decrease when the thickness of nanoparticle arrays increases from monolayer to multilayers, but start to level off at the thickness of 4–5 monolayers. The energy barriers are characterized by the coefficient ?D at ES-VRH regime and the activation energy Ea at SH regime. Moreover, a turning point for the temperature coefficient of conductance was observed in multilayer nanoparticle arrays at high temperature, which is attributed to the increasing mobility with decreasing temperature of hopping transport in three dimensions. PMID:25523836

Wang, Ying; Duan, Chao; Peng, Lianmao; Liao, Jianhui

2014-01-01

319

Studies of Azimuthal Modulations in Two Hadron Fragmentation of a Transversely Polarised Quark  

E-print Network

We study the azimuthal modulations of dihadron fragmentation functions (DiFFs) of a transversely polarised quark using an NJL-jet based model that incorporates the Collins effect for single hadron emission. The DiFFs are extracted as Monte Carlo (MC) averages of corresponding multiplicities using their probabilistic interpretation. To simplify the model and highlight the possible mechanisms that create this modulation, we choose the elementary Collins function to be proportional to the elementary unpolarised fragmentation and a constant probability ($P_{SF}$) for the quark to flip its spin after a single hadron emission. Moreover, as a leading order calculation, only one of the produced hadrons in the decay chain of the quark is produced with elementary Collins modulation. We calculate the dependence of the polarised DiFFs on various angles such as the azimuthal angle of the single hadron and the angle of the two hadron production plane $\\varphi_R$ for several values of $P_{SF}$. We observe that the polarised DiFFs for oppositely charged pion pairs exhibit a $\\sin(\\varphi_R)$ modulation. This effect is induced purely via the elementary Collins effect and persists even when the quark completely depolarises after a single hadron emission ($P_{SF}=0.5$). Moreover, similar sine modulations are present in the distribution of pion pairs with respect to the azimuthal angle of their total transverse momentum, $\\varphi_T$.

Hrayr H. Matevosyan; Aram Kotzinian; Anthony W. Thomas

2014-02-18

320

Studies of azimuthal modulations in two hadron fragmentation of a transversely polarised quark  

NASA Astrophysics Data System (ADS)

We study the azimuthal modulations of dihadron fragmentation functions (DiFFs) of a transversely polarised quark using an NJL-jet based model that incorporates the Collins effect for single hadron emission. The DiFFs are extracted as Monte Carlo (MC) averages of corresponding multiplicities using their probabilistic interpretation. To simplify the model and highlight the possible mechanisms that create this modulation, we choose the elementary Collins function to be proportional to the elementary unpolarised fragmentation and a constant probability (PSF) for the quark to flip its spin after a single hadron emission. Moreover, as a leading order calculation, only one of the produced hadrons in the decay chain of the quark is produced with elementary Collins modulation. We calculate the dependence of the polarised DiFFs on various angles such as the azimuthal angle of the single hadron and the angle of the two-hadron production plane ?R for several values of PSF. We observe that the polarised DiFFs for oppositely charged pion pairs exhibit a sin(?R) modulation. This effect is induced purely via the elementary Collins effect and persists even when the quark completely depolarises after a single hadron emission (PSF=0.5). Moreover, similar sine modulations are present in the distribution of pion pairs with respect to the azimuthal angle of their total transverse momentum, ?T.

Matevosyan, Hrayr H.; Kotzinian, Aram; Thomas, Anthony W.

2014-04-01

321

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

322

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

323

Correlating Humidity-Dependent Ionically Conductive Surface Area with Transport Phenomena in Proton-Exchange Membranes  

SciTech Connect

The objective of this effort was to correlate the local surface ionic conductance of a Nafion? 212 proton-exchange membrane with its bulk and interfacial transport properties as a function of water content. Both macroscopic and microscopic proton conductivities were investigated at different relative humidity levels, using electrochemical impedance spectroscopy and current-sensing atomic force microscopy (CSAFM). We were able to identify small ion-conducting domains that grew with humidity at the surface of the membrane. Numerical analysis of the surface ionic conductance images recorded at various relative humidity levels helped determine the fractional area of ion-conducting active sites. A simple square-root relationship between the fractional conducting area and observed interfacial mass-transport resistance was established. Furthermore, the relationship between the bulk ionic conductivity and surface ionic conductance pattern of the Nafion? membrane was examined.

He, Qinggang; Kusoglu, Ahmet; Lucas, Ivan T.; Clark, Kyle; Weber, Adam Z.; Kostecki, Robert

2011-08-01

324

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

325

Benchmark solutions for the galactic ion transport equations: Energy and spatially dependent problems  

NASA Technical Reports Server (NTRS)

Nontrivial benchmark solutions are developed for the galactic ion transport (GIT) equations in the straight-ahead approximation. These equations are used to predict potential radiation hazards in the upper atmosphere and in space. Two levels of difficulty are considered: (1) energy independent, and (2) spatially independent. The analysis emphasizes analytical methods never before applied to the GIT equations. Most of the representations derived have been numerically implemented and compared to more approximate calculations. Accurate ion fluxes are obtained (3 to 5 digits) for nontrivial sources. For monoenergetic beams, both accurate doses and fluxes are found. The benchmarks presented are useful in assessing the accuracy of transport algorithms designed to accommodate more complex radiation protection problems. In addition, these solutions can provide fast and accurate assessments of relatively simple shield configurations.

Ganapol, Barry D.; Townsend, Lawrence W.; Wilson, John W.

1989-01-01

326

Low Growth Temperature-Induced Increase in Light Saturated Photosystem I Electron Transport Is Cation Dependent 1  

PubMed Central

Thylakoid membranes isolated from cold tolerant, herbaceous monocots and dicots grown at 5°C exhibit a 1.5-fold to 2.7-fold increase in light saturated rates of photosystem I (PSI) electron transport compared to thylakoids isolated from the same plant species grown at 20°C. This was observed only when either water or reduced dichlorophenolindophenol was used as an electron donor. The apparent quantum yield for PSI electron transport was not affected by growth temperature. The higher light saturated rates of PSI electron transport in 5°C thylakoids had an absolute requirement for the presence of Na+ and Mg+2. The accessibility of reduced dichlorophenolindophenol to the donor site was not affected by growth temperature since 5°C and 20°C thylakoids exhibited no significant difference in the concentration of this electron donor required for half-maximal PSI activity. The cation dependent higher rates of light saturated PSI activity were also observed when rye thylakoids were developed under intermittent light conditions at 5°C. Thus, this cation effect on PSI activity appeared to be independent of light harvesting complex I and II. The extent of the in vitro reversibility of this cation effect appeared to be limited by an inherent decay process for PSI electron transport. The rate of decay for PSI activity was greatest when thylakoids were isolated in the absence of NaCl and MgCl2. We conclude that exposure of plants to low growth temperatures induces a reorganization of thylakoid membranes which increases the light saturated rates of PSI electron transport with no change in the apparent quantum efficiency for this reaction. Cations are required to stabilize this reorganization. Images Figure 4 Figure 5 PMID:16667181

Huner, Norman P. A.; Reynolds, Tracey L.

1989-01-01

327

Amphetamine Distorts Stimulation-Dependent Dopamine Overflow: Effects on D2 Autoreceptors, Transporters, and Synaptic  

E-print Network

Amphetamine Distorts Stimulation-Dependent Dopamine Overflow: Effects on D2 Autoreceptors York 10032, and 4Universite´ Victor Segalen, Bordeaux 33076, France Amphetamine (AMPH) is known sensitization. Key words: dopamine; amphetamine; uptake; amperometry; cyclic voltammetry; D2 receptor

Sulzer, David

328

Voltage-Dependent Proton Transport by the Voltage Sensor of the Shaker K + Channel  

Microsoft Academic Search

In voltage-dependent ion channels, pore opening is initiated by electrically driven movements of charged residues, and this movement generates a gating current. To examine structural rearrangements in the Shaker K+ channel, basic residues R365 and R368 in the S4 segment were replaced with histidine, and gating currents were recorded. Changes in gating charge displacement with solvent pH reveal voltage-dependent changes

Dorine M. Starace; Enrico Stefani; Francisco Bezanilla

1997-01-01

329

Magnetic Field-Dependent Interplay Between Incoherent and Fermi Liquid Transport Mechanisms in Low-Dimensional Tau Phase Organic Conductors  

NSDL National Science Digital Library

The US Department of Energy (DOE) Office of Scientific and Technical Information (OSTI) has recently posted a preprint in the field of condensed matter physics in its archive. The third, "Magnetic field-dependent interplay between incoherent and Fermi liquid transport mechanisms in low-dimensional tau phase organic conductors," contains recent experimental results from researchers at Florida State University's National High Magnetic Field Laboratory and the Theoretical and Physical Chemistry Research Institute of Greece. The URL takes readers to the abstract page, from which the full text can be downloaded in .dvi, .ps, or .pdf format.

Balicas, L.; Brooks, J. S.; Graf, D.; Papavassiliou, George C.; Storr, K.

2000-01-01

330

Subject dependent transfer functions in spatial hearing  

Microsoft Academic Search

Head Related Transfer Functions (HRTF's) characterize the transformation of pressure waves from the sound source to the listener's eardrums. They are of central interest to binaural hearing and to sound localization. The HRTF is a function of the azimuth and elevation of the sound source, and may vary from subject to subject. The functional dependence of the HRTF on azimuth

V. Ralph Algazi; Pierre L. Divenyi; V. A. Martinez; R. O. Duda

1997-01-01

331

Reduced striatal dopamine transporter density associated with working memory deficits in opioid-dependent male subjects: a SPECT study.  

PubMed

Research on the effects of repeated opioid use on striatal dopamine transporters (DATs) has yielded inconsistent results, possibly confounded by a history of methamphetamine or methadone exposure in opioid-dependent individuals. Previous studies have shown that striatal DAT density is positively correlated with the cognitive performance of healthy volunteers. This study aimed to investigate changes in striatal DAT density and their functional significance in opioid-dependent individuals. Single-photon emission computed tomography (SPECT) with [(99m) Tc]TRODAT-1 as a ligand was used to measure striatal DAT levels in 20 opioid-dependent individuals and 20 age- and sex-matched healthy controls. Opioid-dependent individuals had no history of methamphetamine or methadone use. The Wisconsin Card Sorting Test (WCST) was performed to assess neurocognitive function. We found that compared with healthy controls, opioid-dependent individuals showed a significant reduction in striatal DAT density. They also showed poorer performance on the WCST in terms of the trials administered, total errors, perseverative responses, perseverative errors and non-perseverative errors. Striatal DAT levels negatively correlated with non-perseverative errors not only in opioid-dependent individuals but also in healthy controls. These findings suggest that in human, repeated opioid exposure reduces striatal DAT density, which can be associated with non-perseverative errors. Non-perseverative errors may be one of the more sensitive parameters in WCST to identify working memory deficits associated with striatal DAT reduction. Moreover, we suggest that whether opioid-associated neurotoxicity is reversible depends on the brain region. PMID:25439653

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

2014-12-01

332

Angle-dependent magnetoresistance in the weakly incoherent interlayer transport regime in a layered organic conductor.  

PubMed

We present comparative studies of the orientation effect of a strong magnetic field on the interlayer resistance of alpha-(BEDT-TTF)2KHg(SCN)4 samples characterized by different crystal quality. We find striking differences in their behavior, which is attributed to the breakdown of the coherent charge transport across the layers in the lower quality sample. In the latter case, the nonoscillating magnetoresistance background is essentially a function of only the out-of-plane field component, in contradiction to the existing Fermi-liquid theories. PMID:16712253

Kartsovnik, M V; Andres, D; Simonov, S V; Biberacher, W; Sheikin, I; Kushch, N D; Müller, H

2006-04-28

333

LETTER TO THE EDITOR: Spin-dependent quantum transport effects in Cu nanowires  

NASA Astrophysics Data System (ADS)

In this work we investigate quantum transport in Cu nanowires created by bringing macroscopic Cu wires into and out of contact under an applied magnetic field in air. Here we show that a 70% magneto-conductance effect can be seen in a Cu nanowire in a field of 2 mT at room temperature. We propose that this phenomenon is a consequence of spin filtering due to the adsorption of atmospheric oxygen modifying the electronic band structure and introducing spin-split conduction channels. This is a remarkable result since bulk Cu is not magnetic and it may provide a new perspective in the quest for spintronic devices.

Gillingham, D. M.; Müller, C.; Bland, J. A. C.

2003-05-01

334

Presynaptic Na+-dependent transport and exocytose of GABA and glutamate in brain in hypergravity.  

NASA Astrophysics Data System (ADS)

?-Aminobutyric acid (GABA) and L-glutamate are the most widespread neurotransmitter amino acids in the mammalian central nervous system. GABA is now widely recognized as the major inhibitory neurotransmitter. L-glutamate mediates the most of excitatory synaptic neurotransmission in the brain. They involved in the main aspects of normal brain function. The nerve terminals (synaptosomes) offer several advantages as a model system for the study of general mechanisms of neurosecretion. Our data allowed to conclude that exposure of animals to hypergravity (centrifugation of rats at 10G for 1 hour) had a profound effect on synaptic processes in brain. Comparative analysis of uptake and release of GABA and glutamate have demonstrated that hypergravity loading evokes oppositely directed alterations in inhibitory and excitatory signal transmission. We studied the maximal velocities of [^3H]GABA reuptake and revealed more than twofold enhancement of GABA transporter activity (Vmax rises from 1.4 |pm 0.3 nmol/min/mg of protein in the control group to 3.3 ± 0.59 nmol/min/mg of protein for animals exposed to hypergravity (P ? 0.05)). Recently we have also demonstrated the significant lowering of glutamate transporter activity (Vmax of glutamate reuptake decreased from 12.5 ± 3.2 nmol/min/mg of protein in the control group to 5.6 ± 0.9 nmol/min/mg of protein in the group of animals, exposed to the hypergravity stress (P ? 0.05)). Significant changes occurred in release of neurotransmitters induced by stimulating exocytosis with the agents, which depolarized nerve terminal plasma membrane. Depolarization-evoked Ca2+-stimulated release was more abundant for GABA (7.2 ± 0.54% and 11,74 ±1,2 % of total accumulated label for control and hypergravity, respectively (P?0.05)) and was essentially less for glutamate (14.4 ± 0.7% and 6.2 ± 1.9%) after exposure of animals to centrifuge induced artificial gravity. Changes observed in depolarization-evoked exocytotic release seem to be in a concert with alterations of plasma membrane transporters activity studied. Perhaps, lowering of glutamate transporter activity and increase of the velocity of GABA uptake correlated with diminution and augmentation of exocytotic release of these neurotransmitters, respectively. It is possible to suggest that observed changes in the activity of the processes responsible for the uptake and release of excitatory and inhibitory neurotransmitters are likely to be physiologically important and reflect making protective mechanisms more active for neutralization of harm influence of hypergravity stress.

Borisova, T.; Pozdnyakova, N.; Krisanova, N.; Himmelreich, N.

335

Haemophilus parainfluenzae expresses diverse lipopolysaccharide O-antigens using ABC transporter and Wzy polymerase-dependent mechanisms  

PubMed Central

Lipopolysaccharide O-antigens are the basis of serotyping schemes for Gram negative bacteria and help to determine the nature of host–bacterial interactions. Haemophilus parainfluenzae is a normal commensal of humans but is also an occasional pathogen. The prevalence, diversity and biosynthesis of O-antigens were investigated in this species for the first time. 18/18 commensal H. parainfluenzae isolates contain a O-antigen biosynthesis gene cluster flanked by glnA and pepB, the same position as the hmg locus for tetrasaccharide biosynthesis in Haemophilus influenzae. The O-antigen loci show diverse restriction digest patterns but fall into two main groups: (1) those encoding enzymes for the synthesis and transfer of FucNAc4N in addition to the Wzy-dependent mechanism of O-antigen synthesis and transport and (2) those encoding galactofuranose synthesis/transfer enzymes and an ABC transporter. The other glycosyltransferase genes differ between isolates. Three H. parainfluenzae isolates fell outside these groups and are predicted to synthesise O-antigens containing ribitol phosphate or deoxytalose. Isolates using the ABC transporter system encode a putative O-antigen ligase, required for the synthesis of O-antigen-containing LPS glycoforms, at a separate genomic location. The presence of an O-antigen contributes significantly to H. parainfluenzae resistance to the killing effect of human serum in vitro. The discovery of O-antigens in H. parainfluenzae is striking, as its close relative H. influenzae lacks this cell surface component. PMID:24035104

Young, Rosanna E.B.; Twelkmeyer, Brigitte; Vitiazeva, Varvara; Power, Peter M.; Schweda, Elke K.H.; Hood, Derek W.

2013-01-01

336

Cooperative, ATP-dependent association of the nucleotide binding cassettes during the catalytic cycle of ATP-binding cassette transporters.  

PubMed

ATP-binding cassette (ABC) transporters harvest the energy present in cellular ATP to drive the translocation of a structurally diverse set of solutes across the membrane barriers of eubacteria, archaebacteria, and eukaryotes. The positively cooperative ATPase activity (Hill coefficient, 1.7) of a model soluble cassette of known structure, MJ0796, from Methanococcus jannaschii indicates that at least two binding sites participate in the catalytic reaction. Mutation of the catalytic base in MJ0796, E171Q, produced a cassette that can bind but not efficiently hydrolyze ATP. The equivalent mutation (E179Q) in a homologous cassette, MJ1267, had an identical effect. Both mutant cassettes formed dimers in the presence of ATP but not ADP, indicating that the energy of ATP binding is first coupled to the transport cycle through a domain association reaction. The non-hydrolyzable nucleotides adenosine 5'-(beta,gamma-imino)triphosphate and adenosine 5'-3-O-(thio)triphosphate were poor analogues of ATP in terms of their ability to promote dimerization. Moreover, inclusion of MgCl2, substitution of KCl for NaCl, or alterations in the polarity of the side chain at the catalytic base all weakened the ATP-dependent dimer, suggesting that electrostatic interactions are critical for the association reaction. Thus, upon hydrolysis of bound ATP and the release of product, both electrostatic and conformational changes drive the cassettes apart, providing a second opportunity to couple free energy changes to the transport reaction. PMID:11964392

Moody, Jonathan E; Millen, Linda; Binns, Derk; Hunt, John F; Thomas, Philip J

2002-06-14

337

Time-dependent scenario modeling of the Tokamak Physics Experiment using a theory-based transport model  

NASA Astrophysics Data System (ADS)

Predictive transport and current drive simulations are presented for the time evolution of the temperature and density profiles in the Tokamak Physics Experiment (TPX). [W. M. Nevins et al., Proceedings of the International Conference on Plasma Physics and Controlled Nuclear Fusion Research, Würzburg, 1992 (International Atomic Energy Agency, Vienna, 1992), Vol. 3, p. 279]. A distinguishing feature of this study is that we use a theoretically derived transport model that has been empirically calibrated against Ohmic, low-confinement and high-confinement mode discharges from seven different tokamaks. Heating and deposition profiles predicted by the ACCOME current drive and magnetohydrodynamic equilibrium code [R. S. Devoto et al., Nucl. Fusion 32, 773 (1992)] are incorporated into the time-dependent BALDUR one-and-one-half dimensional transport code [C. E. Singer et al., Comput. Phys. Commun. 49, 275 (1988)]. We consider various scenarios of fast wave, lower hybrid, and neutral beam heating and current drive and evaluate the effects on the evolution of density and temperature profiles.

Kinsey, Jon; Kritz, Arnold; Bonoli, Paul; Porkolab, Miklos

1996-03-01

338

Fluorinated pickering emulsions impede interfacial transport and form rigid interface for the growth of anchorage-dependent cells.  

PubMed

This study describes the design and synthesis of amphiphilic silica nanoparticles for the stabilization of aqueous drops in fluorinated oils for applications in droplet microfluidics. The success of droplet microfluidics has thus far relied on one type of surfactant for the stabilization of drops. However, surfactants are known to have two key limitations: (1) interdrop molecular transport leads to cross-contamination of droplet contents, and (2) the incompatibility with the growth of adherent mammalian cells as the liquid-liquid interface is too soft for cell adhesion. The use of nanoparticles as emulsifiers overcomes these two limitations. Particles are effective in mitigating undesirable interdrop molecular transport as they are irreversibly adsorbed to the liquid-liquid interface. They do not form micelles as surfactants do, and thus, a major pathway for interdrop transport is eliminated. In addition, particles at the droplet interface provide a rigid solid-like interface to which cells could adhere and spread, and are thus compatible with the proliferation of adherent mammalian cells such as fibroblasts and breast cancer cells. The particles described in this work can enable new applications for high-fidelity assays and for the culture of anchorage-dependent cells in droplet microfluidics, and they have the potential to become a competitive alternative to current surfactant systems for the stabilization of drops critical for the success of the technology. PMID:25347285

Pan, Ming; Rosenfeld, Liat; Kim, Minkyu; Xu, Manqi; Lin, Edith; Derda, Ratmir; Tang, Sindy K Y

2014-12-10

339

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

340

Separation of Rashba and Dresselhaus spin-orbit interactions using crystal direction dependent transport measurements  

SciTech Connect

The Rashba spin-orbit interaction effective field is always in the plane of the two-dimensional electron gas and perpendicular to the carrier wavevector but the direction of the Dresselhaus field depends on the crystal orientation. These two spin-orbit interaction parameters can be determined separately by measuring and analyzing the Shubnikov-de Haas oscillations for various crystal directions. In the InAs quantum well system investigated, the Dresselhaus term is just 5% of the Rashba term. The gate dependence of the oscillation patterns clearly shows that only the Rashba term is modulated by an external electric field.

Ho Park, Youn [Spin Convergence Research Center, Korea Institute of Science and Technology (KIST), Seoul 136-791 (Korea, Republic of) [Spin Convergence Research Center, Korea Institute of Science and Technology (KIST), Seoul 136-791 (Korea, Republic of); Department of Materials Science and Engineering, Yonsei University, Seoul 120-749 (Korea, Republic of); Kim, Hyung-jun; Chang, Joonyeon; Hee Han, Suk [Spin Convergence Research Center, Korea Institute of Science and Technology (KIST), Seoul 136-791 (Korea, Republic of)] [Spin Convergence Research Center, Korea Institute of Science and Technology (KIST), Seoul 136-791 (Korea, Republic of); Eom, Jonghwa [Department of Physics and Graphene Research Institute, Sejong University, Seoul 143-747 (Korea, Republic of)] [Department of Physics and Graphene Research Institute, Sejong University, Seoul 143-747 (Korea, Republic of); Choi, Heon-Jin [Department of Materials Science and Engineering, Yonsei University, Seoul 120-749 (Korea, Republic of)] [Department of Materials Science and Engineering, Yonsei University, Seoul 120-749 (Korea, Republic of); Cheol Koo, Hyun, E-mail: hckoo@kist.re.kr [Spin Convergence Research Center, Korea Institute of Science and Technology (KIST), Seoul 136-791 (Korea, Republic of); KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul 136-701 (Korea, Republic of)

2013-12-16

341

An ATP-dependent As(III)-glutathione transport system in membrane vesicles of Leishmania tarentolae.  

PubMed Central

Membrane preparations enriched in plasma membrane vesicles prepared from promastigotes of Leishmania tarentolae were shown to accumulate thiolate derivatives of 73As(III). Free arsenite was transported at a low rate, but rapid accumulation was observed after reaction with reduced glutathione (GSH) conditions that favor the formation of As(GS)3. Accumulation required ATP but not electrochemical energy, indicating that As(GS)3 is transported by an ATP-coupled pump. Pentostam, a Sb(V)-containing drug that is one of the first-line therapeutic agents for treatment of leishmaniasis, inhibited uptake after reaction with GSH. Vesicles prepared from a strain in which both copies of the pgpA genes were disrupted accumulated As(GS)3 at wild-type levels, demonstrating that the PgpA protein is not the As(GS)3 pump. These results have important implications for the mechanism of drug resistance in the trypanosomatidae, suggesting that a plasma membrane As(GS)3 pump catalyzes active extrusion of metal thiolates, including the Pentostam-glutathione conjugate. PMID:8700907

Dey, S; Ouellette, M; Lightbody, J; Papadopoulou, B; Rosen, B P

1996-01-01

342

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

NASA Astrophysics Data System (ADS)

Tritium behavior in the solid breeder blanket is one of the key factors in determining tritium self-sufficiency, as well as safety, of fusion reactors. Therefore, it is important to understand the tritium transport mechanisms and processes, in order to accurately determine the tritium release and inventory in the blanket. A model has been developed at UCLA to describe the tritium behavior in solid breeder materials, together with a computer code which can predict the tritium release and inventory. However, the model was limited in some cases: for example, it did not include the capability to account for surface to bulk fluxes and for trapping inside the grain which can have major effects on the tritium transport. The model capabilities have been extended to enable its application over a wide range of experimental conditions. Improvements include: (1) implementing an initial model to account for the general effect of trapping in the bulk, (2) addition of a dissolution flux which would enable a more accurate modeling of solubility driven by hydrogen partial pressure in the solid breeder porosity, (3) inclusion of more hydrogen isotopes species in the pore, and, (4) modification of the existing computer code to allow for broader application, such as the possibility of accounting for both first order and second order adsorption/desorption. The code was used to analyze experimental data on tritium behavior in Li 2O from the BEATRIX-II experiment.

Badawi, A.; Raffray, A. R.; Abdou, M. A.

343

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. PMID:25246864

2014-01-01

344

Phase dependence of transport-aperture coordination variability reveals control strategy of reach-to-grasp movements.  

PubMed

Based on an assumption of movement control optimality in reach-to-grasp movements, we have recently developed a mathematical model of transport-aperture coordination (TAC), according to which the hand-target distance is a function of hand velocity and acceleration, aperture magnitude, and aperture velocity and acceleration (Rand et al. in Exp Brain Res 188:263-274, 2008). Reach-to-grasp movements were performed by young adults under four different reaching speeds and two different transport distances. The residual error magnitude of fitting the above model to data across different trials and subjects was minimal for the aperture-closure phase, but relatively much greater for the aperture-opening phase, indicating considerable difference in TAC variability between those phases. This study's goal is to identify the main reasons for that difference and obtain insights into the control strategy of reach-to-grasp movements. TAC variability within the aperture-opening phase of a single trial was found minimal, indicating that TAC variability between trials was not due to execution noise, but rather a result of inter-trial and inter-subject variability of motor plan. At the same time, the dependence of the extent of trial-to-trial variability of TAC in that phase on the speed of hand transport was sharply inconsistent with the concept of speed-accuracy trade-off: the lower the speed, the larger the variability. Conversely, the dependence of the extent of TAC variability in the aperture-closure phase on hand transport speed was consistent with that concept. Taking into account recent evidence that the cost of neural information processing is substantial for movement planning, the dependence of TAC variability in the aperture-opening phase on task performance conditions suggests that it is not the movement time that the CNS saves in that phase, but the cost of neuro-computational resources and metabolic energy required for TAC regulation in that phase. Thus, the CNS performs a trade-off between that cost and TAC regulation accuracy. It is further discussed that such trade-off is possible because, due to a special control law that governs optimal switching from aperture opening to aperture closure, the inter-trial variability of the end of aperture opening does not affect the high accuracy of TAC regulation in the subsequent aperture-closure phase. PMID:20931181

Rand, Miya K; Shimansky, Y P; Hossain, Abul B M I; Stelmach, George E

2010-11-01

345

Measurement of the anisotropy factor with azimuthal light backscattering  

NASA Astrophysics Data System (ADS)

The potential capability of low coherence backscattering (LBS) is explored to determine the anisotropy factor based on azimuthal light backscattering map. The scattering intensity signal measured at azimuthal angle ?=0° is extracted for analysis. By performing nonlinear regression fitting on the experimental signal to the Henyey-Greenstein phase function, the anisotropy factor is determined. The experiments with tissue phantom consisting of the aqueous suspension of polystyrene microspheres are carried out. The results show that the measured anisotropy factor is well described by Mie theory.

Wang, Pin; Li, Yong-ming; Chen, Bo-han

2014-11-01

346

WKB thresholds of standard, helical, and azimuthal magnetorotational instability  

NASA Astrophysics Data System (ADS)

We consider rotating flows of an electrically conducting, viscous and resistive fluid in an external magnetic field with arbitrary combinations of axial and azimuthal components. Within the short-wavelength approximation, the local stability of the flow is studied with respect to perturbations of arbitrary azimuthal wavenumbers. In the limit of vanishing magnetic Prandtl number (Pm) we find that the maximum critical Rossby number (Ro) for the occurrence of the magnetorotational instability (MRI) is universally governed by the Liu limit {Ro}Liu=2-2&sqrt;{2}? -0.828$ which is below the value for Keplerian rotation Ro Kepler = -0.75.

Kirillov, Oleg; Stefani, Frank

2013-02-01

347

Trap densities and transport properties of pentacene metal-oxide-semiconductor transistors. I. Analytical modeling of time-dependent characteristics  

NASA Astrophysics Data System (ADS)

Metal-oxide-semiconductor (MOS) transistors fabricated with pentacene thin films were characterized by temperature-dependent current-voltage (I-V) characteristics, time-dependent current measurements, and admittance spectroscopy. The channel mobility shows almost linear variation with temperature, suggesting that only shallow traps are present in the semiconductor and at the oxide/semiconductor interface. The admittance spectra feature a broad peak, which can be modeled as the sum of a continuous distribution of relaxation times. The activation energy of this peak is comparable to the polaron binding energy in pentacene. The absence of trap signals in the admittance spectra confirmed that both the semiconductor and the oxide/semiconductor interface have negligible density of deep traps, likely owing to the passivation of SiO2 before pentacene growth. Nevertheless, current instabilities were observed in time-dependent current measurements following the application of gate-voltage pulses. The corresponding activation energy matches the energy of a hole trap in SiO2. We show that hole trapping in the oxide can explain both the temperature and the time dependences of the current instabilities observed in pentacene MOS transistors. The combination of these experimental techniques allows us to derive a comprehensive model for charge transport in hybrid architectures where trapping processes occur at various time and length scales.

Basile, A. F.; Cramer, T.; Kyndiah, A.; Biscarini, F.; Fraboni, B.

2014-06-01

348

Particle production azimuthal asymmetries in a clustering of color sources model  

E-print Network

The collective interactions of many partons in the first stage of the collisions is the usual accepted explanation of the sizable elliptical flow. The clustering of color sources provides a framework of partonic interactions. In this scheme, we show a reasonable agreement with RHIC data for pT<1.5 GeV/c in both the dependence of v2 transverse momentum and in the shape of the nuclear modified factor on the azimuthal angle for different centralities. We show the predictions at LHC energies for Pb-Pb. In the case of proton-proton collisions a sizable v2 is obtained at this energy.

I. Bautista; L. Cunqueiro; J. Dias de Deus; C. Pajares

2009-05-19

349

A novel mode of current switching dependent on activated charge transport  

NASA Astrophysics Data System (ADS)

We demonstrate a fully printed transistor with a planar triode geometry, using nanoparticulate silicon as the semiconductor material, which has a unique mode of operation as an electrically controlled two-way (double throw) switch. A signal applied to the base changes the direction of the current from between the collector and base to between the base and emitter. We further show that the switching characteristic results from the activated charge transport in the semiconductor material, and that it is independent of the dominant carrier type in the semiconductor and the nature of the junction between the semiconductor and the three contacts. The same equivalent circuit, and hence similar device characteristics, can be produced using any other material combination with non-linear current-voltage characteristics, such as a suitable combination of semiconducting and conducting materials, such that a Schottky junction is present at all three contacts.

Britton, David T.; Walton, Stanley D.; Zambou, Serges; Magunje, Batsirai; Jonah, Emmanuel O.; Härting, Margit

2013-08-01

350

Details of Sample Dependence and Transport Properties of URu2Si2  

NASA Astrophysics Data System (ADS)

Resistivity and specific heat measurements were performed in the low carrier unconventional superconductor URu2Si2 on various samples with very different qualities. The superconducting transition temperature (TSC) and the hidden order transition temperature (THO) of these crystals were evaluated as a function of the residual resistivity ratio (RRR). In high quality single crystals the resistivity does not seem to follow a T2 dependence above TSC, indicating that the Fermi liquid regime is restricted to low temperatures. However, an analysis of the isothermal longitudinal magnetoresistivity points out that the T2 dependence may be ``spoiled'' by residual inhomogeneous superconducting contribution. We discuss a possible scenario concerning the distribution of TSC related with the fact that the hidden order phase is very sensitive to the pressure inhomogeneity.

Matsuda, Tatsuma D.; Hassinger, Elena; Aoki, Dai; Taufour, Valentin; Knebel, Georg; Tateiwa, Naoyuki; Yamamoto, Etsuji; Haga, Yoshinori; ?nuki, Yoshichika; Fisk, Zachary; Flouquet, Jacques

2011-11-01

351

Arabidopsis root growth dependence on glutathione is linked to auxin transport  

Microsoft Academic Search

Glutathione depletion, e.g. by the inhibitor of its synthesis, buthionine sulphoximine (BSO), is well known to specifically\\u000a reduce primary root growth. To obtain an insight into the mechanism of this inhibition, we explored the effects of BSO on\\u000a Arabidopsis root growth in more detail. BSO inhibits root growth and reduces glutathione (GSH) concentration in a concentration-dependent\\u000a manner leading to a

Anna Koprivova; Sam T. Mugford; Stanislav Kopriva

2010-01-01

352

Na-dependent L-proline transport by eel intestinal brush-border membrane vesicles  

SciTech Connect

L-({sup 3}H)proline uptake by brush-border membrane vesicles prepared from intestinal mucosa of the European eel, Anguilla anguilla, was stimulated by a transmembrane Na gradient (out > in.) Kinetic analysis of L-proline influx, under short-circuited membrane potential conditions, indicated the presence of an apparent single Na-dependent carrier process and a nonsaturable transfer component with an apparent diffusional permeability (P) of 1.53 {plus minus} 0.35 {mu}l{center dot}mg protein{sup {minus}1}{center dot}min{sup {minus}1}. An imposed transmembrane potential (inside negative) increased apparent L-proline binding affinity (lowered K{sub app}) without appreciably altering maximal amino acid influx (J{sub max}). Hill analysis of L-proline influx over a wide range of external Na concentrations indicated a 1:1 stoichiometry for Na-proline cotransport. Use of amino acid inhibitors of L-proline influx suggested that L-proline transfer may occur by either a classical Na-dependent A System with a wide substrate specificity or by the combination of Na-dependent PHE (phenylalanine preferring) and IMINO (proline, {alpha}-methylaminoisobutyric acid preferring) Systems.

Vilella, S.; Ahearn, G.A.; Cassano, G.; Storelli, C. (Universita' di Lecce (Italy) University of Hawaii at Manoa, Honolulu (USA))

1988-10-01

353

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

354

Lysine 27 ubiquitination of the mitochondrial transport protein Miro is dependent on serine 65 of the Parkin ubiquitin ligase.  

PubMed

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

2014-05-23

355

Transportation  

NSDL National Science Digital Library

A unit designed to increase students' knowledge and understanding of diesel and gasoline engines, providing an introduction for students interested in more specialized training in the automobile field and its scientific principles through math, science, and chemistry. It will also help students realize the importance of transportation, and will help them meet their needs in math through problem solving by dealing with materials in their world, letting them develop skills and techniques through hands-on experience. Includes more than 20 problems to solve.

Bryant, Joyce

2007-05-12

356

Range ambiguity suppression for multiple-input, multiple-output synthetic aperture radar system using azimuth phase coding technique  

NASA Astrophysics Data System (ADS)

For synthetic aperture radar (SAR), range ambiguity causes a great deterioration in imaging performance. To suppress range ambiguity, the azimuth phase coding (APC) technique stands out for its effectiveness with a low implementation complexity among the available approaches. With proper phase modulation and demodulation, the position of an ambiguous signal is shifted in Doppler spectrum and then part of the ambiguity can be filtered out by an azimuth filter. However, since the suppression performance heavily depends on the system oversampling rate, the APC technique cannot achieve the same suppression performance for a multichannel SAR system compared with a single-channel SAR system. A method to suppress the range ambiguity for multiple-input, multiple-output (MIMO) SAR system based on APC technique is presented. By taking advantage of more phase centers of the MIMO SAR, a proper azimuth beamformer weight vector can be computed to null out the ambiguity position in the azimuth frequency domain and reconstruct the useful signal; thus most of the ambiguity components can be significantly suppressed. Finally, the simulation results validate the effectiveness of the proposed method.

Guo, Lei; Wang, Robert; Deng, Yunkai; Wang, Wei; Luo, Xiulian

2014-01-01

357

A Family-Based Analysis of Whether the Functional Promoter Alleles of the Serotonin Transporter Gene HTT Affect the Risk for Alcohol Dependence  

Microsoft Academic Search

A population association between a regulatory variation in the pro- moter of the serotonin transporter gene (Hrr) and severe alcohol dependence was recently reported. We analyzed this potential asso- ciation in a large number of systematically ascertained families in the United States; these families had at least three first-degree relatives who were alcohol-dependent. Analyses focused on individuals de- fined as

Howard J. Edenberg; Jennifer Reynolds; Daniel L. Koller; Henri Begleiter; Kathleen K. Bucholz; P. Michael Conneally; Raymond Crowe; Alison Goate; Victor Hesselbrock; T.-K. Li; John I. Nurnberger; Bernice Porjesz; Theodore Reich; John P. Rice; Marc Schuckit; Jay A. Tischfield; Tatiana Foroud

1998-01-01

358

Expression and water calcium dependence of calcium transporter isoforms in zebrafish gill mitochondrion-rich cells  

PubMed Central

Background Freshwater fish absorb Ca2+ predominantly from ambient water, and more than 97% of Ca2+ uptake is achieved by active transport through gill mitochondrion-rich (MR) cells. In the current model for Ca2+ uptake in gill MR cells, Ca2+ passively enters the cytosol via the epithelium Ca2+ channel (ECaC), and then is extruded into the plasma through the basolateral Na+/Ca2+ exchanger (NCX) and plasma membrane Ca2+-ATPase (PMCA). However, no convincing molecular or cellular evidence has been available to support the role of specific PMCA and/or NCX isoforms in this model. Zebrafish (Danio rerio) is a good model for analyzing isoforms of a gene because of the plentiful genomic databases and expression sequence tag (EST) data. Results Using a strategy of BLAST from the zebrafish genome database (Sanger Institute), 6 isoforms of PMCAs (PMCA1a, PMCA1b, PMCA2, PMCA3a, PMCA3b, and PMCA4) and 7 isoforms of NCXs (NCX1a, NCX1b, NCX2a, NCX2b, NCX3, NCX4a, and NCX4b) were identified. In the reverse-transcriptase polymerase chain reaction (RT-PCR) analysis, 5 PMCAs and 2 NCXs were ubiquitously expressed in various tissues including gills. Triple fluorescence in situ hybridization and immunocytochemistry showed the colocalization of zecac, zpmca2, and zncx1b mRNAs in a portion of gill MR cells (using Na+-K+-ATPase as the marker), implying a subset of ionocytes specifically responsible for the transepithelial Ca2+ uptake in zebrafish gills. The gene expressions in gills of high- or low-Ca2+-acclimated zebrafish by quantitative real-time PCR analysis showed that zecac was the only gene regulated in response to environmental Ca2+ levels, while zpmcas and zncxs remained steady. Conclusion The present study provides molecular evidence for the specific isoforms of Ca2+ transporters, zECaC, zPMCA2, and zNCX1b, supporting the current Ca2+ uptake model, in which ECaC may play a role as the major regulatory target for this mechanism during environmental challenge. PMID:17915033

Liao, Bo-Kai; Deng, Ang-Ni; Chen, Shyh-Chi; Chou, Ming-Yi; Hwang, Pung-Pung

2007-01-01

359

Mixed harmonic azimuthal correlations in Pb--Pb collisions at \\sqrt{s_{NN}}=2.76TeV measured with the ALICE experiment at the LHC  

E-print Network

Mixed harmonic charge dependent azimuthal correlations at mid-rapidity in Pb-Pb collisions at \\sqrt{s_{NN}} = 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 local parity violation in QCD and for models which incorporate azimuthal anisotropic flow and "effective" local charge conservation on the kinetic freeze-out surface are discussed.

Y. Hori for the ALICE collaboration

2013-01-30

360

Origin of power-law composition dependence in ionic transport glasses  

NASA Astrophysics Data System (ADS)

The origin of a power-law correlation between ionic conductivity and cation-contents, found commonly in oxide and chalcogenide glasses, is discussed using the concept of configuration entropy. It is suggested that power-law dependence is primarily attributed to an increase in configuration entropy with mixing cation components into glasses. This effect reduces the potential barrier height to be surmounted by mobile ions, which results in a higher diffusion coefficient (and hence conductivity). The origin of anomalous pre-exponential factors of diffusion coefficient and conductivity can be interpreted in terms of the present context.

Shimakawa, K.; Wagner, T.

2013-04-01

361

Effect of dopamine transporter genotype on intrinsic functional connectivity depends on cognitive state.  

PubMed

Functional connectivity between brain regions can define large-scale neural networks and provide information about relationships between those networks. We examined how relationships within and across intrinsic connectivity networks were 1) sensitive to individual differences in dopaminergic function, 2) modulated by cognitive state, and 3) associated with executive behavioral traits. We found that regardless of cognitive state, connections between frontal, parietal, and striatal nodes of Task-Positive networks (TPNs) and Task-Negative networks (TNNs) showed higher functional connectivity in 10/10 homozygotes of the dopamine transporter gene, a polymorphism influencing synaptic dopamine, than in 9/10 heterozygotes. However, performance of a working memory task (a state requiring dopamine release) modulated genotype differences selectively, such that cross-network connectivity between TPNs and TNNs was higher in 10/10 than 9/10 subjects during working memory but not during rest. This increased cross-network connectivity was associated with increased self-reported measures of impulsivity and inattention traits. By linking a gene regulating synaptic dopamine to a phenotype characterized by inefficient executive function, these findings validate cross-network connectivity as an endophenotype of executive dysfunction. PMID:22047966

Gordon, Evan M; Stollstorff, Melanie; Devaney, Joseph M; Bean, Stephanie; Vaidya, Chandan J

2012-09-01

362

Shear-rate dependent transport coefficients in a binary mixture of Maxwell molecules  

NASA Astrophysics Data System (ADS)

Mass and heat transport in a dilute binary mixture of Maxwell molecules under steady shear flow are studied in the limit of small concentration gradients. The analysis is made from the Gross-Krook kinetic model of the Boltzmann equation. This model is solved by means of a perturbation solution around the steady shear flow solution [Phys. Fluids 8, 2756 (1996)], which applies for arbitrary values of the shear rate. In the first order of the expansion the results show that the mass and heat fluxes are proportional to the concentration gradient but, due to the anisotropy of the problem, mutual diffusion and Dufour tensors can be identified, respectively. Both tensors are explicitly determined in terms of the shear rate and the parameters of the mixture (particle masses, concentrations, and force constants). A comparison with the results derived from the exact Boltzmann equation at the level of the diffusion tensor shows a good agreement for a wide range of values of the shear rate.

Marín, C.; Garzó, V.; López de Haro, M.

2000-03-01

363

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

364

Na+ dependent acid-base transporters in the choroid plexus; insights from slc4 and slc9 gene deletion studies  

PubMed Central

The choroid plexus epithelium (CPE) is located in the ventricular system of the brain, where it secretes the majority of the cerebrospinal fluid (CSF) that fills the ventricular system and surrounds the central nervous system. The CPE is a highly vascularized single layer of cuboidal cells with an unsurpassed transepithelial water and solute transport rate. Several members of the slc4a family of bicarbonate transporters are expressed in the CPE. In the basolateral membrane the electroneutral Na+ dependent Cl?/HCO3? exchanger, NCBE (slc4a10) is expressed. In the luminal membrane, the electrogenic Na+:HCO3? cotransporter, NBCe2 (slc4a5) is expressed. The electroneutral Na+:HCO3? cotransporter, NBCn1 (slc4a7), has been located in both membranes. In addition to the bicarbonate transporters, the Na+/H+ exchanger, NHE1 (slc9a1), is located in the luminal membrane of the CPE. Genetically modified mice targeting slc4a2, slc4a5, slc4a7, slc4a10, and slc9a1 have been generated. Deletion of slc4a5, 7 or 10, or slc9a1 has numerous impacts on CP function and structure in these mice. Removal of the transporters affects brain ventricle size (slc4a5 and slc4a10) and intracellular pH regulation (slc4a7 and slc4a10). In some instances, removal of the proteins from the CPE (slc4a5, 7, and 10) causes changes in abundance and localization of non-target transporters known to be involved in pH regulation and CSF secretion. The focus of this review is to combine the insights gathered from these knockout mice to highlight the impact of slc4 gene deletion on the CSF production and intracellular pH regulation resulting from the deletion of slc4a5, 7 and 10, and slc9a1. Furthermore, the review contains a comparison of the described human mutations of these genes to the findings in the knockout studies. Finally, the future perspective of utilizing these proteins as potential targets for the treatment of CSF disorders will be discussed. PMID:24155723

Christensen, Henriette L.; Nguyen, An T.; Pedersen, Fredrik D.; Damkier, Helle H.

2013-01-01

365

Scale-Dependent Fracture-Matrix Interactions and Their Impact on Radionuclide Transport: Development of efficient particle-tracking methods  

SciTech Connect

Matrix Diffusion and Adsorption within a rock matrix are important mechanisms for retarding transport of radionuclides in fractured rock. Due to computational limitations and difficulties in characterizing complex subsurface systems, diffusive exchange between a fracture network and surrounding rock matrix is often modeled using simplified conceptual representations. There is significant uncertainty in “effective” parameters used in these models, such as the “effective matrix diffusivity”. Often, these parameters are estimated by fitting sparse breakthrough data, and estimated values fall outside meaningful ranges, because simplified interpretive models do not consider complex three-dimensional flow. There is limited understanding of the relationship between the effective parameters and rock mass characteristics including network structure and matrix properties. There is also evidence for an apparent scale-dependence in “effective matrix diffusion” coefficients. These observations raise questions on whether fracture-matrix interaction parameters estimated from small-scale tracer tests can be used for predicting radionuclide fate and transport at the scale of DOE field sites. High-resolution three-dimensional Discrete-Fracture-Network-Matrix (DFNM) models based on well-defined local scale transport equations can help to address some of these questions. Due to tremendous advances in computational technology over the last 10 years, DFNM modeling in relatively large domains is now feasible. The overarching objective of our research is to use DFNM modeling to improve fundamental understanding of how effective parameters in conceptual models are related to fracture network structure and matrix properties. An advanced three-dimensional DFNM model is being developed, which combines upscaled particle-tracking algorithms for fracture-matrix interaction and a parallel fracture-network flow simulator. The particle-tracking algorithms allow complexity in flow fields at different scales, and track transport across fracture-matrix interfaces based on rigorous local approximations to the transport equations. This modeling approach can incorporate aperture variability, multi-scale preferential flow and matrix heterogeneity. We developed efficient particle-tracking methods for handling matrix diffusion and adsorption on fracture walls and demonstrated their efficiency for use within the context of large-scale complex fracture network models with variability in apertures across a network of fractures and within individual fractures.

Rajaram, Harihar [University of Colorado, Boulder; Brutz, Michael [University of Colorado, Boulder; Klein, Dylan R [University of Colorado, Boulder; Mallikamas, Wasin [University of Colorado, Boulder

2014-09-18

366

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

367

Polarimetric SAR data compensation for terrain azimuth slope variation  

Microsoft Academic Search

This paper addresses the problem of polarimetric SAR (POLSAR) data correction for changes in radar cross sections, which are caused by azimuth slopes. Most radiometric slope corrections remove slope effects to account for the effective scattering pixel area. However, few studies address the slope effect on the radar cross section as a function of polarization states. The authors propose two

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

2000-01-01

368

AZIMUTHAL VARIATION OF RADIATION OF SEISMIC ENERGY FROM CAST BLASTS  

E-print Network

the variation of vibration intensity at various angles (azimuths) from large cast blasts. These effects characteristics, blasting personnel can use this information to mitigate vibration effects on local structures could mitigate problems with vibration levels from future blasting operations. Regionally, the local

369

Propagation in Shielded Helical Line Containing Azimuthally Magnetised Latching Ferrite  

Microsoft Academic Search

The propagation in an infinitely long thin-wire cylindrical helix, surrounded by a latching ferrite tube, magnetised azimuthally to remanence and perfectly conducting metallic shield is studied theoretically. The characteristic equation of the system for circularly symmetrical mode, involving the normalized phase constant, structure geometry, latching ferrite parameters and frequency is derived in terms of modified Bessel functions and Tricomi confluent

K. P. Ivanov

1977-01-01

370

Some properties of the circular waveguide with azimuthally magnetized ferrite  

Microsoft Academic Search

A comprehensive analysis of normal rotationally symmetric TE modes in a circular waveguide, filled with ferrite, magnetized azimuthally to remanence by a coaxial switching conductor of finite radius, is presented. The characteristic equation of the structure, derived in terms of Kummer and Tricomi confluent hypergeometric functions of complex parameter and variable, is solved numerically, using specially compiled tables of wave

Kamen P. Ivanov; Georgi N. Georgiev

1990-01-01

371

Azimuth Variation in Microwave Backscatter over the Greenland Ice Sheet  

E-print Network

/ablation balance of the Greenland Ice Sheet is considered a sensitive indicator of global climate change. AlthoughAzimuth Variation in Microwave Backscatter over the Greenland Ice Sheet Ivan S. Ashcraft and David backscatter measurements are becoming an important tool for monitoring the dynamic behavior of the Greenland

Long, David G.

372

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

373

Azimuthally acoustic logging tool to evaluate cementing quality  

NASA Astrophysics Data System (ADS)

An azimuthally sensitive acoustic bond tool (AABT) uses a phased arc array transmitter that can provide directionally focused radiation. The acoustic sonde consists of a phased arc array transmitter and two monopole receivers, the spaces from the transmitter being 0.91?m and 1.52?m, respectively. The transmitter includes eight transducer sub-units. By controlling the high-voltage firing signal phase for each transmitter, the radiation energy of the phased arc array transducer can be focused in a single direction. Compared with conventional monopole and dipole transmitters, the new transmitter provides cement quality evaluation with azimuthal sensitivity, which is not possible with conventional cement bond log/variable density log tools. Laboratory measurements indicate that the directivity curves for the phased arc array and those computed theoretically are consistent and show good agreement. We acquire measurements from a laboratory cistern and from the field to validate the reliability and applicability of the AABT. Results indicate that the AABT accurately evaluates the azimuthal cement quality of case-cement interfaces by imaging the amplitude of the first-arrival wave. This tool visualizes the size, position and orientation of channeling and holes. In the case of good case-cement bonding, the AABT also evaluates the azimuthal cementing quality of the cement formation interface by imaging the amplitude of formation waves.

Lu, Junqiang; Ju, Xiaodong; Qiao, Wenxiao; Men, Baiyong; Wang, Ruijia; Wu, Jinping

2014-08-01

374

Vacuum Calculations in Azimuthally Symmetric Geometry M. S. Chance  

E-print Network

Vacuum Calculations in Azimuthally Symmetric Geometry M. S. Chance Princeton University Plasma, the eddy currents and the simulation of Mirnov loop measurements are calculated. PACS: 52.35.Py, 52.55.Fa and accurate calculation of these eects is available to insure that numerical uncertainties in the overall

375

Vacuum Calculations in Azimuthally Symmetric Geometry \\Lambda M. S. Chance  

E-print Network

Vacuum Calculations in Azimuthally Symmetric Geometry \\Lambda M. S. Chance Princeton University are calculated. PACS: 52.35.Py, 52.55.Fa, 52.55.Hc, 52.35.Bj I. Introduction The solution of the perturbed. It is convenient if a robust and accurate calculation of these effects is available to insure that numerical

376

Azimuthal plasma pressure gradient in quiet time plasma sheet  

Microsoft Academic Search

We have investigated the quiet-time azimuthal plasma pressure gradient in the plasma sheet at a radial distance of 10 RE to 12 RE using two THEMIS spacecraft that were in overlapping orbits during the 2008 THEMIS tail season. The equatorial plasma pressure is estimated by using the in-situ measurement of the plasma pressure and magnetic pressure based on pressure balance

X. Xing; L. R. Lyons; V. Angelopoulos; D. Larson; J. McFadden; C. Carlson; A. Runov; U. Auster

2009-01-01

377

Bifurcation of the endocytic pathway into Rab5-dependent and -independent transport to the vacuole  

NASA Astrophysics Data System (ADS)

The yeast Rab5 homologue, Vps21p, is known to be involved both in the vacuolar protein sorting (VPS) pathway from the trans-Golgi network to the vacuole, and in the endocytic pathway from the plasma membrane to the vacuole. However, the intracellular location at which these two pathways converge remains unclear. In addition, the endocytic pathway is not completely blocked in yeast cells lacking all Rab5 genes, suggesting the existence of an unidentified route that bypasses the Rab5-dependent endocytic pathway. Here we show that convergence of the endocytic and VPS pathways occurs upstream of the requirement for Vps21p in these pathways. We also identify a previously unidentified endocytic pathway mediated by the AP-3 complex. Importantly, the AP-3-mediated pathway appears mostly intact in Rab5-disrupted cells, and thus works as an alternative route to the vacuole/lysosome. We propose that the endocytic traffic branches into two routes to reach the vacuole: a Rab5-dependent VPS pathway and a Rab5-independent AP-3-mediated pathway.

Toshima, Junko Y.; Nishinoaki, Show; Sato, Yoshifumi; Yamamoto, Wataru; Furukawa, Daiki; Siekhaus, Daria Elisabeth; Sawaguchi, Akira; Toshima, Jiro

2014-03-01

378

Ileal apical sodium-dependent bile acid transporter protein levels are down-regulated through ubiquitin-dependent protein degradation induced by bile acids.  

PubMed

The ileal apical sodium-dependent bile acid transporter (ASBT or SLC10A2) has a crucial role in intestinal bile acid absorption. We previously reported that enterobacteria-mediated bile acid conversion was involved in the alteration of ileal ASBT expression levels. In the present study, to investigate the hypothesis that ileal ASBT protein levels are post-translationally regulated by enterobacteria-associated bile acids, alteration of ileal ASBT protein levels was analysed in mice 12 h and 24 h after anti-bacterial drug ampicillin (ABPC) treatment (100 mg/kg, single shot) that altered bile acid composition in the intestinal lumen. In ABPC-treated mice, enterobacteria-biotransformed bile acid, taurodeoxycholic acid (TDCA) and cholic acid (CA) levels were decreased, whereas taurocholic acid (TCA) and tauro-?-muricholic acid levels were increased in the intestinal lumen. Ileal ASBT protein levels in brush-border membrane vesicles (BBMVs), but not ileal Asbt mRNA levels, were significantly increased in the ABPC-treated mice, and the extent of ubiquitination of the ileal ASBT protein was reduced in the ABPC-treated mice. Treatment of ABPC-pretreated mice with CA or TDCA, but not TCA, significantly decreased ileal ASBT protein levels and increased the extent of ubiquitination of ileal ASBT protein. Treatment of mice with the lysosome inhibitor, chloroquine, or the proteasome inhibitor, MG132, increased ileal ASBT protein levels in BBMVs. CA-mediated reduction of ASBT protein levels in the ABPC-pretreated mice was attenuated by co-treatment with chloroquine or MG132. These results suggest that ileal ASBT protein is degraded by a ubiquitin-dependent pathway in response to enterobacteria-associated bile acids. PMID:23872411

Miyata, Masaaki; Yamakawa, Hiroki; Hayashi, Kenjiro; Kuribayashi, Hideaki; Yamazoe, Yasushi; Yoshinari, Kouichi

2013-08-15

379

Studying the energy dependence of elliptic and directed flow within a relativistic transport approach  

NASA Astrophysics Data System (ADS)

The energy excitation functions of directed flow (v1) and elliptic flow (v2) from Ebeam=90 A MeV to Ecm=200 A GeV are explored within the UrQMD framework and discussed in the context of the available data. The radial and the elliptic flow of the particles produced in a relativistic heavy-ion collision are intimately connected to the pressure and its gradients in the early stage of the reaction. Therefore, these observables should also be sensitive to changes in the equation of state. To prove this connection, the temporal evolution of the pressure, pressure gradients and elliptic flow are shown. For the flow excitation functions it is found that, in the energy regime below Ebeam?10 A GeV, the inclusion of nuclear potentials is necessary to describe the data. Above 40 A GeV beam energy, the UrQMD model starts to underestimate the elliptic flow. Around the same energy the slope of the rapidity spectra of the proton directed flow develops negative values. This effect is known as the third flow component (“antiflow”) and cannot be reproduced by the transport model. The difference between the data and the UrQMD model can possibly be explained by assuming a phase transition from hadron gas to quark gluon plasma around Elab=40 A GeV. This would be consistent with the model calculations, indicating a transition from hadronic matter to “string matter” in this energy range. Thus, we speculate that the missing pressure might be generated by strong interactions in the early pre-hadronic/partonic phase of central Au + Au (Pb + Pb) collisions already at lower SPS energies.

Petersen, H.; Bleicher, M.

2007-01-01

380

Biotin uptake by T47D breast cancer cells: functional and molecular evidence of sodium-dependent multivitamin transporter (SMVT).  

PubMed

The objective of this study was to investigate functional and molecular evidence of carrier mediated system responsible for biotin uptake in breast cancer (T47D) cells and to delineate mechanism of intracellular regulation of this transporter. Cellular accumulation of [3H] biotin was studied in T47D and normal mammary epithelial (MCF-12A) cells. Reverse transcription polymerase chain reaction (RT-PCR) was carried out to confirm the molecular expression of sodium dependent multivitamin transporter (SMVT) in T47D cells. Quantitative real time PCR analysis was also performed to compare the relative expression of SMVT in T47D and MCF-12A cells. [3H] biotin uptake by T47D cells was found to be concentration dependent with K(m) of 9.24 ?M and V(max) of 27.34 pmol/mg protein/min. Uptake of [3H] biotin on MCF-12A cells was also found to be concentration dependent and saturable, but with a relatively higher K(m) (53.10 ?M) indicating a decrease in affinity of biotin uptake in normal breast cells compared to breast cancer cells. [3H] biotin uptake appears to be time-, temperature-, pH- and sodium ion-dependent but independent of energy and chloride ions. [3H] biotin uptake was significantly inhibited in the presence of biotin, its structural analog desthiobiotin, pantothenic acid and lipoic acid. Concentration dependent inhibition of biotin uptake was evident in the presence of valeric acid which possesses free carboxyl group and biocytin and NHS biotin which are devoid of free carboxyl group. No significant inhibition was observed in the presence of structurally unrelated vitamins (ascorbic acid, folic acid, nicotinic acid, thiamine, pyridoxine and riboflavin). Modulators of PTK, PKC and PKA mediated pathways had no effect, but uptake in presence of calmidazolium (calcium-calmodulin inhibitor) was significantly inhibited. [3H] biotin uptake in the presence of calmidazolium was found to be saturable with a K(m) and V(max) values of 13.49 ?M and 11.20 pmol/mg protein/min, respectively. A band of SMVT mRNA at 774 bp was identified by RT-PCR analysis. Quantitative real time PCR confirmed higher expression of SMVT in T47D cells relative to MCF-12A cells. All these studies demonstrated for the first time the functional and molecular expression of sodium dependent multivitamin transporter (SMVT), a specific carrier-mediated system for biotin uptake, in human derived breast cancer (T47D) cells. The present study also indicated that cancer cells could import more vitamin compared to normal breast cells possibly for maintaining high proliferative status. We investigated the likelihood of selecting this cell line (T47D) as an in vitro cell culture model to study biotin-conjugated anti-cancer drugs/drug delivery systems. PMID:23142496

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

2013-01-30

381

Sodium-dependent vitamin C transporter SVCT2: Expression and Function in bone marrow stromal cells and in Osteogenesis  

PubMed Central

Ascorbic acid (Vitamin C) has a critical role in bone formation and osteoblast differentiation, but very little is known about the molecular mechanisms of ascorbic acid entry into bone marrow stromal cells (BMSCs). To address this gap in knowledge, we investigated the identity of the transport system that is responsible for the uptake of ascorbic acid into bone marrow stromal cells (BMSCs). First, we examined the expression of the two known isoforms of the sodium-coupled ascorbic acid transporter, namely SVCT1 and SVCT2, in BMSCs (Lin-ve Sca1+ve) and bone at the mRNA level. Only SVCT2 mRNA was detected in BMSCs and bone. Uptake of ascorbic acid in BMSCs was Na+-dependent and saturable. In order to define the role of SVCT2 in BMSC differentiation into osteoblasts, BMSCs were stimulated with osteogenic media for different time intervals, and the activity of SVCT2 was monitored by ascorbic acid uptake. SVCT2 expression was up-regulated during the osteogenic differentiation of BMSCs; the expression was maximal at the earliest phase of differentiation. Subsequently, osteogenesis was inhibited in BMSCs upon knock-down of SVCT2 by lentivirus shRNA. We also found that the expression of the SVCT2 could be negatively or positively modulated by the presence of oxidant (Sin-1) or antioxidant (Ascorbic acid) compounds, respectively, in BMSCs. Furthermore, we found that this transporter is also regulated with age in mouse bone. These data show that SVCT2 plays a vital role in the osteogenic differentiation of BMSCs and that its expression is altered under conditions associated with redox reaction. Our findings could be relevant to bone tissue engineering and bone related diseases such as osteoporosis in which oxidative stress and aging plays important role. PMID:23089627

Fulzele, Sadanand; Chothe, Paresh; Sangani, Rajnikumar; Chutkan, Norman; Hamrick, Mark; Bhattacharyya, Maryka; Prasad, Puttur D.; Zakhary, Ibrahim; Bowser, Matthew; Isales, Carlos; Ganapathy, Vadivel

2012-01-01

382

Field and temperature dependent electron transport properties of random network single walled and multi walled carbon nanotubes  

NASA Astrophysics Data System (ADS)

Field and temperature dependent electron transport properties of random network single walled carbon nanotubes (SWCNTs) and multi walled carbon nanotubes (MWCNTs) were investigated and compared. The electrical characterizations of drop casted CNT samples were done by two probe measurements by varying temperatures from 80 K to 300 K in the field region 1-400 V cm-1. The charge transport mechanisms at low (<3.5 V) and high (>3.5 V) fields were analyzed from measured I-V characteristic curves at various temperatures (<300 K) with respect to applied field. At low field, the ohmic behavior was observed and at high field the charge transport appears to be Poole-Frenkel type in both types of CNTs network. Electron-electron and electron-phonon scatterings in the localized defect states dominate in SWCNTs, whereas in MWCNTs the delocalization of charge carriers as well as the scattering centers is responsible due to the presence of inner shells. Because of the different nature of chirality in random network, the SWCNTs displayed lower conduction when compared to MWCNTs. The variation in Poole-Frenkel co-efficient (?) (SWCNTs-0.193 × 10-22 MWCNTs-0.089 07 × 10-22 J V1/2 cm-1/2), activation energy (SWCNTs-90 meV; MWCNTs-60 meV for field of 7\\;{{V}^{1/2}}\\;c{{m}^{-1/2}}) and trap energy levels (SWCNTs-109 meV; MWCNTs-37 meV) are discussed for both SWCNTs and MWCNTs.

Rajavel, K.; Verma, S.; Asokan, K.; Rajendra Kumar, R. T.

2014-09-01

383

Inhibitors of the 5-lipoxygenase arachidonic acid pathway induce ATP release and ATP-dependent organic cation transport in macrophages.  

PubMed

We have previously described that arachidonic acid (AA)-5-lipoxygenase (5-LO) metabolism inhibitors such as NDGA and MK886, inhibit cell death by apoptosis, but not by necrosis, induced by extracellular ATP (ATPe) binding to P2X7 receptors in macrophages. ATPe binding to P2X7 also induces large cationic and anionic organic molecules uptake in these cells, a process that involves at least two distinct transport mechanisms: one for cations and another for anions. Here we show that inhibitors of the AA-5-LO pathway do not inhibit P2X7 receptors, as judged by the maintenance of the ATPe-induced uptake of fluorescent anionic dyes. In addition, we describe two new transport phenomena induced by these inhibitors in macrophages: a cation-selective uptake of fluorescent dyes and the release of ATP. The cation uptake requires secreted ATPe, but, differently from the P2X7/ATPe-induced phenomena, it is also present in macrophages derived from mice deficient in the P2X7 gene. Inhibitors of phospholipase A2 and of the AA-cyclooxygenase pathway did not induce the cation uptake. The uptake of non-organic cations was investigated by measuring the free intracellular Ca(2+) concentration ([Ca(2+)]i) by Fura-2 fluorescence. NDGA, but not MK886, induced an increase in [Ca(2+)]i. Chelating Ca(2+) ions in the extracellular medium suppressed the intracellular Ca(2+) signal without interfering in the uptake of cationic dyes. We conclude that inhibitors of the AA-5-LO pathway do not block P2X7 receptors, trigger the release of ATP, and induce an ATP-dependent uptake of organic cations by a Ca(2+)- and P2X7-independent transport mechanism in macrophages. PMID:24743022

da Silva-Souza, Hercules Antônio; Lira, Maria Nathalia de; Costa-Junior, Helio Miranda; da Cruz, Cristiane Monteiro; Vasconcellos, Jorge Silvio Silva; Mendes, Anderson Nogueira; Pimenta-Reis, Gabriela; Alvarez, Cora Lilia; Faccioli, Lucia Helena; Serezani, Carlos Henrique; Schachter, Julieta; Persechini, Pedro Muanis

2014-07-01

384

Sec24- and ARFGAP1-dependent trafficking of GABA transporter-1 is a prerequisite for correct axonal targeting.  

PubMed

The GABA transporter-1 (GAT1) is a prototypical protein of the synaptic specialization. Export of GAT1 from the endoplasmic reticulum (ER) is contingent on its interaction with the COPII (coatomer protein-II) coat subunit Sec24D. Here we show that silencing all four Sec24 isoforms strongly inhibits transport of GAT1 to the cell surface. In contrast, transport of GAT1-RL/AS, a mutant that is deficient in Sec24D recruitment, was not inhibited, suggesting a nonconventional, COPII-independent pathway. However, ARFGAP1 bound directly to the C terminus of both GAT1-RL/AS and wild-type GAT1. Surface expression of GAT1-RL/AS involved ARFGAP1. GAT1-RL/AS appeared to bypass the ER-Golgi-intermediate compartment, but its pathway to the plasma membrane still involved passage through the Golgi. Thus, the GAT1-RL/AS mutant allowed to test whether COPII-dependent ER-export is required for correct sorting of GAT1 to the axon terminal in neuronal cells. In contrast to wild-type GAT1, GAT1-RL/AS failed to be specifically enriched at the tip of neurite extensions of CAD.a cells (a neuroblastoma cell line that can be differentiated into a neuron-like phenotype) and in the axon terminals of hippocampal neurons. These findings indicate that correct sorting to the axon is contingent on ER export via the COPII machinery and passage through the ER-Golgi-intermediate compartment. PMID:19020038

Reiterer, Veronika; Maier, Susanne; Sitte, Harald H; Kriz, Alexander; Rüegg, Markus A; Hauri, Hans-Peter; Freissmuth, Michael; Farhan, Hesso

2008-11-19

385

Anomalous temperature dependent transport through single colloidal nanorods strongly coupled to metallic leads.  

PubMed

We report wiring of individual colloidal nanorods (NRs), 30-60 nm long by 3.5-5 nm diameter. Strong electrical coupling is achieved by electron beam induced deposition (EBID) of metallic lines targeting NR tips with nanometric precision. At T = 4 K many devices exhibit smooth I(V) curves with no sharp onset features, which remarkably fit a Fowler-Nordheim tunneling model. All devices exhibit an anomalous exponential temperature dependence of the form I approximately exp(T/T(0)). This irregular behavior cannot be explained by any hopping or activation model and is interpreted by accounting for the lowering of the NR conduction band due to lattice dilation and phonon coupling. PMID:19691333

Steinberg, Hadar; Lilach, Yigal; Salant, Asaf; Wolf, Omri; Faust, Adam; Millo, Oded; Banin, Uri

2009-11-01

386

A role for cyclin-dependent kinase(s) in the modulation of fast anterograde axonal transport: effects defined by olomoucine and the APC tumor suppressor protein  

NASA Technical Reports Server (NTRS)

Proteins that interact with both cytoskeletal and membrane components are candidates to modulate membrane trafficking. The tumor suppressor proteins neurofibromin (NF1) and adenomatous polyposis coli (APC) both bind to microtubules and interact with membrane-associated proteins. The effects of recombinant NF1 and APC fragments on vesicle motility were evaluated by measuring fast axonal transport along microtubules in axoplasm from squid giant axons. APC4 (amino acids 1034-2844) reduced only anterograde movements, whereas APC2 (aa 1034-2130) or APC3 (aa 2130-2844) reduced both anterograde and retrograde transport. NF1 had no effect on organelle movement in either direction. Because APC contains multiple cyclin-dependent kinase (CDK) consensus phosphorylation motifs, the kinase inhibitor olomoucine was examined. At concentrations in which olomoucine is specific for cyclin-dependent kinases (5 microM), it reduced only anterograde transport, whereas anterograde and retrograde movement were both affected at concentrations at which other kinases are inhibited as well (50 microM). Both anterograde and retrograde transport also were inhibited by histone H1 and KSPXK peptides, substrates for proline-directed kinases, including CDKs. Our data suggest that CDK-like axonal kinases modulate fast anterograde transport and that other axonal kinases may be involved in modulating retrograde transport. The specific effect of APC4 on anterograde transport suggests a model in which the binding of APC to microtubules may limit the activity of axonal CDK kinase or kinases in restricted domains, thereby affecting organelle transport.

Ratner, N.; Bloom, G. S.; Brady, S. T.

1998-01-01

387

Mus spicilegus Endogenous Retrovirus HEMV Uses Murine Sodium-Dependent Myo-Inositol Transporter 1 as a Receptor  

PubMed Central

We sought to determine the relationship between two recent additions to the murine leukemia virus (MLV) ecotropic subgroup: Mus cervicolor isolate M813 and Mus spicilegus endogenous retrovirus HEMV. Though divergent in sequence, the two viruses share an Env protein with similarly curtailed VRA and VRB regions, and infection by both is restricted to mouse cells. HEMV and M813 displayed reciprocal receptor interference, suggesting that they share a receptor. Expression of the M813 receptor murine sodium-dependent myo-inositol transporter 1 (mSMIT1) allowed previously nonpermissive cells to be infected by HEMV, indicating that mSMIT1 also serves as a receptor for HEMV. Our findings add HEMV as a second member to the MLV subgroup that uses mSMIT1 to gain entry into cells. PMID:22457525

Tipper, Christopher H.; Cingöz, Oya

2012-01-01

388

Mus spicilegus endogenous retrovirus HEMV uses murine sodium-dependent myo-inositol transporter 1 as a receptor.  

PubMed

We sought to determine the relationship between two recent additions to the murine leukemia virus (MLV) ecotropic subgroup: Mus cervicolor isolate M813 and Mus spicilegus endogenous retrovirus HEMV. Though divergent in sequence, the two viruses share an Env protein with similarly curtailed VRA and VRB regions, and infection by both is restricted to mouse cells. HEMV and M813 displayed reciprocal receptor interference, suggesting that they share a receptor. Expression of the M813 receptor murine sodium-dependent myo-inositol transporter 1 (mSMIT1) allowed previously nonpermissive cells to be infected by HEMV, indicating that mSMIT1 also serves as a receptor for HEMV. Our findings add HEMV as a second member to the MLV subgroup that uses mSMIT1 to gain entry into cells. PMID:22457525

Tipper, Christopher H; Cingöz, Oya; Coffin, John M

2012-06-01

389

Pressure dependence of the oxygen reduction reaction at the platinum microelectrode/nafion interface - Electrode kinetics and mass transport  

NASA Technical Reports Server (NTRS)

The investigation of oxygen reduction kinetics at the platinum/Nafion interface is of great importance in the advancement of proton-exchange-membrane (PEM) fuel-cell technology. This study focuses on the dependence of the oxygen reduction kinetics on oxygen pressure. Conventional Tafel analysis of the data shows that the reaction order with respect to oxygen is unity at both high and low current densities. Chronoamperometric measurements of the transport parameters for oxygen in Nafion show that oxygen dissolution follows Henry's isotherm. The diffusion coefficient of oxygen is invariant with pressure; however, the diffusion coefficient for oxygen is lower when air is used as the equilibrating gas as compared to when oxygen is used for equilibration. These results are of value in understanding the influence of O2 partial pressure on the performance of PEM fuel cells and also in elucidating the mechanism of oxygen reduction at the platinum/Nafion interface.

Parthasarathy, Arvind; Srinivasan, Supramaniam; Appleby, A. J.; Martin, Charles R.

1992-01-01

390

Molecular Switch Controlling the Binding of Anionic Bile Acid Conjugates to Human Apical Sodium-dependent Bile Acid Transporter  

PubMed Central

The human apical sodium-dependent bile acid transporter (hASBT) may serve as a prodrug target for oral drug absorption. Synthetic, biological, NMR and computational approaches identified the structure-activity relationships of mono- and dianionic bile acid conjugates for hASBT binding. Experimental data combined with a conformationally-sampled pharmacophore/QSAR modeling approach (CSP-SAR) predicted that dianionic substituents with intramolecular hydrogen bonding between hydroxyls on the cholane skeleton and the acid group on the conjugate's aromatic ring increased conjugate hydrophobicity and improved binding affinity. Notably, the model predicted the presence of a conformational molecular switch, where shifting the carboxylate substituent on an aromatic ring by a single position controlled binding affinity. Model validation was performed by effectively shifting the spatial location of the carboxylate by inserting a methylene adjacent to the aromatic ring, resulting in the predicted alteration in binding affinity. This work illustrates conformation as a determinant of ligand binding affinity to a biological transporter. PMID:20504026

Rais, Rana; Acharya, Chayan; Tririya, Gasirat; MacKerell, Alexander D.; Polli, James E.

2010-01-01

391

The histidine transporter SLC15A4 coordinates mTOR-dependent inflammatory responses and pathogenic antibody production.  

PubMed

SLC15A4 is a lysosome-resident, proton-coupled amino-acid transporter that moves histidine and oligopeptides from inside the lysosome to the cytosol of eukaryotic cells. SLC15A4 is required for Toll-like receptor 7 (TLR7)- and TLR9-mediated type I interferon (IFN-I) productions in plasmacytoid dendritic cells (pDCs) and is involved in the pathogenesis of certain diseases including lupus-like autoimmunity. How SLC15A4 contributes to diseases is largely unknown. Here we have shown that B cell SLC15A4 was crucial for TLR7-triggered IFN-I and autoantibody productions in a mouse lupus model. SLC15A4 loss disturbed the endolysosomal pH regulation and probably the v-ATPase integrity, and these changes were associated with disruption of the mTOR pathway, leading to failure of the IFN regulatory factor 7 (IRF7)-IFN-I regulatory circuit. Importantly, SLC15A4's transporter activity was necessary for the TLR-triggered cytokine production. Our findings revealed that SLC15A4-mediated optimization of the endolysosomal state is integral to a TLR7-triggered, mTOR-dependent IRF7-IFN-I circuit that leads to autoantibody production. PMID:25238095

Kobayashi, Toshihiko; Shimabukuro-Demoto, Shiho; Yoshida-Sugitani, Reiko; Furuyama-Tanaka, Kaori; Karyu, Hitomi; Sugiura, Yuki; Shimizu, Yukiko; Hosaka, Toshiaki; Goto, Motohito; Kato, Norihiro; Okamura, Tadashi; Suematsu, Makoto; Yokoyama, Shigeyuki; Toyama-Sorimachi, Noriko

2014-09-18

392

Dependence of the localization and function of the human cytomegalovirus protein US6 on the transporter associated with antigen processing.  

PubMed

Human cytomegalovirus protein US6 inhibits the transporter associated with antigen processing (TAP), which transports peptides into the endoplasmic reticulum (ER) for binding to major histocompatibility complex (MHC) class I molecules. We demonstrate that, in TAP-deficient cells, US6 is retained in the ER and binds to calnexin, but does not inhibit cell-surface expression of HLA-A201, an MHC class I allele that binds to peptides whose import into the ER is TAP-independent. Furthermore, in TAP-positive cells, US6 reduces the cell-surface expression of HLA-B2705, an MHC class I allele that is dependent on TAP for peptide binding, to a greater extent than that of HLA-A201. These data demonstrate that US6 has differential effects on the cell-surface expression of MHC class I alleles and are consistent with TAP being the sole inhibitory target of US6 in the MHC class I antigen-presentation pathway. PMID:19439551

Dugan, Gillian E; Hewitt, Eric W

2009-09-01

393

Oxygen Dependence and Extravascular Transport of Hypoxia-Activated Prodrugs: Comparison of the Dinitrobenzamide Mustard PR-104A and Tirapazamine  

SciTech Connect

Purpose: To compare oxygen dependence and tissue transport properties of a new hypoxia-activated prodrug, PR-104A, with tirapazamine, and to evaluate the implications for antitumor activity when combined with radiotherapy. Methods and Materials: Oxygen dependence of cytotoxicity was measured by clonogenic assay in SiHa cell suspensions. Tissue transport parameters were determined using SiHa multicellular layers. Spatially resolved pharmacokinetic (PK) and pharmacodynamic (PD) models were developed to predict cell killing in SiHa tumors and tested by clonogenic assay 18 h after treatment with the corresponding phosphate ester, PR-104. Results: The K-value (oxygen concentration to halve cytotoxic potency) of PR-104A was 0.126 {+-} 0.021 {mu}M (10-fold lower than tirapazamine at 1.30 {+-} 0.28 {mu}M). The diffusion coefficient of PR-104A in multicellular layers (4.42 {+-} 0.15 x 10{sup -7} cm{sup 2} s{sup -1}) was lower than that of tirapazamine (1.30 {+-} 0.05 x 10{sup -6} cm{sup 2} s{sup -1}) but PK modeling predicted better penetration to hypoxic cells in tumors because of its slower metabolism. The tirapazamine PK/PD model successfully predicted the measured activity in combination with single-dose radiation against SiHa tumors, and the PR-104A model underpredicted the activity, which was greater for PR-104 than for tirapazamine (at equivalent host toxicity) both with radiation and as a single agent. Conclusion: PR-104/PR-104A has different PK/PD properties from tirapazamine and superior activity with single-dose radiotherapy against SiHa xenografts. We have inferred that PR-104A is better able to kill cells at intermediate partial pressure of oxygen in tumors than implied by the PK/PD model, most likely because of a bystander effect resulting from diffusion of its activated metabolites from severely hypoxic zones.

Hicks, Kevin O. [Auckland Cancer Society Research Centre, University of Auckland School of Medical Sciences, Auckland (New Zealand)], E-mail: k.hicks@auckland.ac.nz; Myint, Hilary; Patterson, Adam V.; Pruijn, Frederik B.; Siim, Bronwyn G.; Patel, Kashyap; Wilson, William R. [Auckland Cancer Society Research Centre, University of Auckland School of Medical Sciences, Auckland (New Zealand)

2007-10-01

394

KdpFABC reconstituted in Escherichia coli lipid vesicles: substrate dependence of the transport rate.  

PubMed

KdpFABC complexes were reconstituted in Escherichia coli lipid vesicles, and ion pumping was activated by addition of ATP to the external medium which corresponds to the cytoplasm under physiological conditions. ATP-driven potassium extrusion was studied in the presence of various substrates potentially influencing transport rate. The pump current was detected as a decrease of the membrane potential by the voltage-sensitive dye DiSC3(5). The results indicate that high cytoplasmic K(+) concentrations have an inhibitory effect on the KdpFABC complex. The pump current decreased to ?25% of the maximal value at 140 mM K(+) and minimal Mg(2+)concentrations. This effect could be counteracted with increased Mg(2+) concentrations on the cytoplasmic side. This observation may be explained by the Gouy-Chapman effect of two Mg(2+) ions probably bound with a K1/2 of 0.8 mM close to the entrance of the access channel to the binding sites. This factor ensures that under physiological conditions the rate-limiting effect of K(+) release is significantly reduced. Also both ADP and inorganic phosphate are able to reduce the turnover rate of the pump by reversing the phosphorylation step (Ki of 151 ?M) and the dephosphorylation step (Ki of 268 ?M), respectively. In the case of the DDM-solubilized KdpFABC complex, activation energy under turnover conditions was previously found to be 55 kJ/mol, and the o-vanadate inhibition constant is shown here to be ?1 ?M, which is in agreement with values reported for other P-type ATPases. In the case of the reconstituted enzyme, however, significant differences were observed that have to be assigned to effects of the lipid bilayer environment. The activation energy was increased by a factor of 2, whereas the inhibition by o-vanadate became reduced in a way that only ?66% of the enzyme could be inhibited and the inhibition constant was increased to a value of ?60 ?M. PMID:25144826

Damnjanovic, Bojana; Apell, Hans-Jürgen

2014-09-01

395

NF-?B signaling and vesicle transport are correlated with the reactivation of the memory trace of morphine dependence  

PubMed Central

Abstract Background Morphine has been widely used as a clinical anesthetic and analgesic. However, abuse of morphine might result in psychological and physiological dependence. Previous studies have indicated that memory mechanisms play critical roles in morphine dependence. Methods Morphine dependence was established in mice utilizing place preference conditioning (CPP). We observed changes in the methylome and transcriptome of the nucleus accumbens during the reactivation of the memory trace. We also monitored for changes in the methylome and transcriptome of mice that were acutely exposed to morphine. Results We detected 165 and 18 differentially expressed genes (DEGs) and 6 and 24 significant methyl-sensitive cut counting (MSCC) windows in the acute morphine treatment and the CPP model, respectively. The changes in the methylome and transcriptome during the acute treatment were mainly caused by a response to the morphine stimulus; most of the DEGs were correlated with hormone or transcription factor activity regulation. The expression levels of Lcn2 and Hspb1, which participate in the activation of NF-?B, were significantly decreased in the CPP morphine treatment model. Besides, the alternative splicing of the curtailed isoform of Caps1 was significantly increased in the CPP morphine-treated group, and the methylation levels of Arf4, Vapa, and Gga3 were decreased. These genes play critical roles in the regulation of the Golgi network. Conclusions The current study indicates that NF-?B signaling and vesicular transport are correlated with the reactivation of the memory trace in morphine-dependent mice. The results obtained in our study agree with previous observations and identify additional candidate genes for further research. Virtual Slides The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1196707364133126 PMID:25012590

2014-01-01

396

Auxiliary Quantization Constraints on the Von Roos Ordering-Ambiguity at Zero Binding Energies; Azimuthally Symmetrized Cylindrical Coordinates  

NASA Astrophysics Data System (ADS)

Using azimuthally symmetrized cylindrical coordinates, we report the consequences of zero-energy quantal states on the von Roos Hamiltonian. A position-dependent mass (PDM) M(?, ?, z) = bzj?2?+1/2 is used. We show that the zero-energy setting not only offers an additional degree of freedom toward feasible separability for the von Roos Hamiltonian, but also manifestly yields auxiliary quantized ambiguity parametric constraints (i.e. the ambiguity parameters are given in terms of quantum numbers).

Mustafa, Omar

2013-06-01

397

Inhibition of apical sodium-dependent bile acid transporter as a novel treatment for diabetes.  

PubMed

Bile acids are recognized as metabolic modulators. The present study was aimed at evaluating the effects of a potent Asbt inhibitor (264W94), which blocks intestinal absorption of bile acids, on glucose homeostasis in Zucker Diabetic Fatty (ZDF) rats. Oral administration of 264W94 for two wk increased fecal bile acid concentrations and elevated non-fasting plasma total Glp-1. Treatment of 264W94 significantly decreased HbA1c and glucose, and prevented the drop of insulin levels typical of ZDF rats in a dose-dependent manner. An oral glucose tolerance test revealed up to two-fold increase in plasma total Glp-1 and three-fold increase in insulin in 264W94 treated ZDF rats at doses sufficient to achieve glycemic control. Tissue mRNA analysis indicated a decrease in farnesoid X receptor (Fxr) activation in small intestines and the liver but co-administration of a Fxr agonist (GW4064) did not attenuate 264W94 induced glucose lowering effects. In summary, our