903 Matching Results

Search Results

Results: 1 - 24 next
open access

First-Principles Theory of Correlated Transport through Nanojunctions

Description: Article on the first-principles theory of correlated transport through nanojunctions.
Date: March 25, 2005
Creator: Ferretti, A.; Calzolari, Arrigo; Di Felice, R.; Manghi, F.; Caldas, Marilia J.; Buongiorno Nardelli, Marco et al.
Partner: UNT College of Arts and Sciences
open access

Selective extraction of copper, mercury, silver and palladium ionsfrom water using hydrophobic ionic liquids.

Description: Extraction of dilute metal ions from water was performed near room temperature with a variety of ionic liquids. Distribution coefficients are reported for fourteen metal ions extracted with ionic liquids containing cations 1-octyl-4-methylpyridinium [4MOPYR]{sup +}, 1-methyl-1-octylpyrrolidinium [MOPYRRO]{sup +} or 1-methyl-1-octylpiperidinium [MOPIP]{sup +}, and anions tetrafluoroborate [BF{sub 4}]{sup +}, trifluoromethyl sulfonate [TfO]{sup +} or nonafluorobutyl sulfonate [NfO]{sup +}. Ionic … more
Date: June 25, 2007
Creator: Papaiconomou, Nicolas; Lee, Jong-Min; Salminen, Justin; VonStosch, Moritz & Prausnitz, John M.
Partner: UNT Libraries Government Documents Department
open access

A Cell-Centered Adaptive Projection Method for the IncompressibleNavier-Stokes Equations in Three Dimensions

Description: We present a method for computing incompressible viscousflows in three dimensions using block-structured local refinement in bothspace and time. This method uses a projection formulation based on acell-centered approximate projection, combined with the systematic use ofmultilevel elliptic solvers to compute increments in the solutiongenerated at boundaries between refinement levels due to refinement intime. We use an L_0-stable second-order semi-implicit scheme to evaluatethe viscous terms. Res… more
Date: September 25, 2007
Creator: Martin, D.F.; Colella, P. & Graves, D.T.
Partner: UNT Libraries Government Documents Department
open access

Design and Performance of the Matching Beamline Between the Bnl Ebis and an Rfq.

Description: A part of a new EBIS-based heavy ion preinjector, the low energy beam transport (LEBT) section between the high current EBIS and the RFQ is a challenging design, because it must serve many functions. In addition to the requirement to provide an efficient matching between the EBIS and the RFQ, this line must serve as a fast ''switchyard'', allowing singly charged ions from external sources to be transported into the EBIS trap region, and extracted, highly charged ions to be deflected to off-axis… more
Date: June 25, 2007
Creator: Alessi, J.; Beebe, E.; Brodowski, J.; Kponou, A.; Okamura, M.; Pikin, A. et al.
Partner: UNT Libraries Government Documents Department
open access

Light-Front Holography and Hadronization at the Amplitude Level

Description: The correspondence between theories in anti-de Sitter space and conformal field theories in physical space-time leads to an analytic, semiclassical model for strongly-coupled QCD which has scale invariance at short distances and color confinement at large distances. Light-front holography is a remarkable feature of AdS/CFT: it allows hadronic amplitudes in the AdS fifth dimension to be mapped to frame-independent light-front wavefunctions of hadrons in physical space-time, thus providing a rela… more
Date: July 25, 2008
Creator: Brodsky, Stanley J.; de Teramond, Guy & Shrock, Robert
Partner: UNT Libraries Government Documents Department
open access

Heavy ion fusion science research for high energy density physics and fusion applications

Description: During the past two years, the U.S. heavy ion fusion science program has made significant experimental and theoretical progress in simultaneous transverse and longitudinal beam compression, ion-beam-driven warm dense matter targets, high brightness beam transport, advanced theory and numerical simulations, and heavy ion target designs for fusion. First experiments combining radial and longitudinal compression of intense ion beams propagating through background plasma resulted in on-axis beam de… more
Date: June 25, 2007
Creator: Logan, B. G.; Bieniosek, F. M.; Barnard, J. J.; Cohen, R. H.; Coleman, J. E.; Davidson, R. C. et al.
Partner: UNT Libraries Government Documents Department
open access

Vibration Measurements to Study the Effect of Cryogen Flow in Superconducting Quadrupole.

Description: The conceptual design of compact superconducting magnets for the International Linear Collider final focus is presently under development. A primary concern in using superconducting quadrupoles is the potential for inducing additional vibrations from cryogenic operation. We have employed a Laser Doppler Vibrometer system to measure the vibrations in a spare RHIC quadrupole magnet under cryogenic conditions. Some preliminary results of these studies were limited in resolution due to a rather lar… more
Date: June 25, 2007
Creator: He, P.; Anerella, M.; Aydin, S.; Ganetis, G.; Harrison, M.; Jain, A. et al.
Partner: UNT Libraries Government Documents Department
open access

Metabolic engineering of Saccharomyces cerevisiae for the production of n-butanol

Description: BackgroundIncreasing energy costs and environmental concerns have motivated engineering microbes for the production of ?second generation? biofuels that have better properties than ethanol.Results& ConclusionsSaccharomyces cerevisiae was engineered with an n-butanol biosynthetic pathway, in which isozymes from a number of different organisms (S. cerevisiae, Escherichia coli, Clostridium beijerinckii, and Ralstonia eutropha) were substituted for the Clostridial enzymes and their effect on n-… more
Date: November 25, 2008
Creator: Steen, EricJ.; Chan, Rossana; Prasad, Nilu; Myers, Samuel; Petzold, Christopher; Redding, Alyssa et al.
Partner: UNT Libraries Government Documents Department
open access

Neutron Soft Errors in Xilinx FPGAs at Lawrence Berkeley National Laboratory

Description: The LBNL 88-Inch Cyclotron offers broad-spectrum neutrons for single event effects testing. We discuss results from this beamline for neutron soft upsets in Xilinx Virtex-4 and -5 field-programmable-gate-array (FPGA) devices.
Date: July 25, 2008
Creator: George, Jeffrey S.; Koga, Rocky & McMahan, Margaret A.
Partner: UNT Libraries Government Documents Department
open access

Executive Summary of the Workshop on Polarization and Beam Energy Measurements at the ILC

Description: This note summarizes the results of the 'Workshop on Polarization and Beam Energy Measurements at the ILC', held at DESY (Zeuthen) April 9-11 2008. The topics for the workshop included (1) physics requirements, (2) polarized sources and low energy polarimetry, (3) BDS polarimeters, (4) BDS energy spectrometers, and (5) physics-based measurements of beam polarization and beam energy from collider data. Discussions focused on the current ILC baseline program as described in the Reference Design R… more
Date: July 25, 2008
Creator: Aurand, B.; Bailey, I.; Bartels, C.; Blair, G.; Brachmann, A.; Clarke, J. et al.
Partner: UNT Libraries Government Documents Department
open access

The Use of Small Coolers in a Magnetic Field

Description: Small 4 K coolers are used to cool superconducting magnets.These coolers are usually used with high temperature suerconductor (HTS)leads. In most cases, magnet is shielded with iron or active shieldcoils. Thus the field at the cooler is low. There are instances when thecooler must be in a magnetic field. Gifford McMahon (GM) coolers or pulsetube coolers are commercially available to cool the magnets. This paperwill discuss how the two types of coolers are affected by the straymagnetic field. St… more
Date: July 25, 2007
Creator: Green, Michael A. & Witte, Holger
Partner: UNT Libraries Government Documents Department
open access

Study of the Decay Ds+ to K+K-e+nu

Description: Using 214 fb{sup -1} of data recorded by the BABAR detector at the PEPII electron-positron collider, they study the decay D{sub s}{sup +} {yields} K{sup +}K{sup -}e{sup +}{nu}{sub e}. Except for a small S-wave contribution, the events with K{sup +}K{sup -} masses in the range 1.01-1.03 GeV/c{sup 2} correspond to {phi} mesons. For D{sub s}{sup +} {yields} {phi}e{sup +}{nu}{sub e} decays, they measure the relative normalization of the Lorentz invariant form factors at q{sup 2} = 0, r{sub V} = V(0… more
Date: July 25, 2008
Creator: Aubert, B.; Bona, M.; Karyotakis, Y.; Lees, J. P.; Poireau, V.; Prencipe, E. et al.
Partner: UNT Libraries Government Documents Department
open access

A Variation of the F-Test for Determining Statistical Relevance ofParticular Parameters in EXAFS Fits

Description: A general problem when fitting EXAFS data is determining whether particular parameters are statistically significant. The F-test is an excellent way of determining relevancy in EXAFS because it only relies on the ratio of the fit residual of two possible models, and therefore the data errors approximately cancel. Although this test is widely used in crystallography (there, it is often called a 'Hamilton test') and has been properly applied to EXAFS data in the past, it is very rarely applied in… more
Date: July 25, 2006
Creator: Downward, L.; Booth, C.H.; Lukens, W.W. & Bridges, F.
Partner: UNT Libraries Government Documents Department
open access

Preparation and Reactions of Base-FreeBis(1,2,4-tri-tert-butylcyclopentadienyl)uranium Oxide, Cp'2UO

Description: Reduction of the uranium metallocene,[eta5-1,2,4-(Me3C)3C5H2]2UCl2 (1), Cp'2UCl2, in the presence of2,2'-bipyridyl and sodium naphthalene gives the dark green metallocenecomplex, Cp'2U(bipy) (6), which reacts with p-tolylazide orpyridine-N-oxide to give Cp'2U=N(p-tolyl) (7) or Cp'2U(O)(py) (8),respectively. The Lewis acid, BPh3, precipitates Ph3B(py) and gives thebase-free oxo, Cp'2UO (10), which crystallizes from pentane. Theoxometallocene 10 behaves as a nucleophile with Me3SiX reagents but i… more
Date: May 25, 2005
Creator: Zi, Guofu; Werkema, Evan L.; Walter, Marc D.; Gottfriedsen,Jochen P. & Andersen, Richard A.
Partner: UNT Libraries Government Documents Department
open access

Isotopic mass-dependence of noble gas diffusion coefficients inwater

Description: Noble gas isotopes are used extensively as tracers inhydrologic and paleoclimatic studies. These applications requireknowledge of the isotopic mass (m) dependence of noble gas diffusioncoefficients in water (D), which has not been measured but is estimatedusing experimental D-values for the major isotopes along with an untestedrelationship from kinetic theory, D prop m-0.5. We applied moleculardynamics methods to determine the mass dependence of D for four noblegases at 298 K, finding that D pr… more
Date: June 25, 2007
Creator: Bourg, I.C. & Sposito, G.
Partner: UNT Libraries Government Documents Department
open access

Spatial Dependence of Condensates in Strongly Coupled Gauge Theories

Description: We analyze quark and gluon condensates in quantum chromodynamics. We suggest that these are localized inside hadrons, because the particles whose interactions are responsible for them are confined within these hadrons. This can explain the results of recent studies of gluon condensate contributions to vacuum correlators. We also give a general discussion of condensates in asymptotically free vectorial and chiral gauge theories.
Date: March 25, 2008
Creator: Brodsky, Stanley J.; /SLAC /SUNY, Stony Brook; Shrock, Robert & /SUNY, Stony Brook
Partner: UNT Libraries Government Documents Department
open access

End-to-End Simulations for the Ebis Preinjector.

Description: The EBIS Project at Brookhaven National Laboratory is in the second year of a four-year project. It will replace the Tandem Van de Graaff accelerators with an Electron Beam Ion Source, an RFQ, and one IH Linac cavity, as the heavy ion preinjector for the Relativistic Heavy Ion Collider (RHIC), and for the NASA Space Radiation Laboratory (NSRL). The preinjector will provide all ions species, He to U, (Q/m >0.16) at 2 MeV/amu at a repetition rate of 5 Hz, pulse length of 10-40 {micro}s, and in… more
Date: June 25, 2007
Creator: Raparia, D.; Alessi, J.; Kponou, A.; Pikin, A.; Ritter, J.; Minaev, S. et al.
Partner: UNT Libraries Government Documents Department
open access

Optical Faraday Cup for Heavy Ion Beams

Description: We have been using alumina scintillators for imaging beams in heavy-ion beam fusion experiments in 2 to 4 transverse dimensions [1]. The scintillator has a limited lifetime under bombardment by the heavy ion beams. As a possible replacement for the scintillator, we are studying the technique of imaging the beam on a gas cloud. A gas cloud for imaging the beam may be created on a solid hole plate placed in the path of the beam, or by a localized gas jet. It is possible to image the beam using ce… more
Date: June 25, 2007
Creator: Bieniosek, Frank; Bieniosek, F. M.; Eylon, S.; Roy, P. K. & Yu, S. S.
Partner: UNT Libraries Government Documents Department
open access

Plasma Lens for Us Based Super Neutrino Beam at Either Fnal or Bnl.

Description: The plasma lens concept is examined as an alternative to focusing horns and solenoids for a neutrino beam facility. The concept is based on a combined high-current lens/target configuration. Current is fed at an electrode located downstream from the beginning of the target where pion capturing is needed. The current is carried by plasma outside the target. A second plasma lens section, with an additional current feed, follows the target. The plasma is immersed in a relatively small solenoidal m… more
Date: June 25, 2007
Creator: Hershcovitch, A.; Weng, W.; Diwan, M.; Gallardo, J.; Kirk, H.; Johnson, B. et al.
Partner: UNT Libraries Government Documents Department
open access

Membrane proteomics of phagosomes suggests a connection to autophagy

Description: Phagocytosis is the central process by which macrophage cellsinternalize and eliminate infectious microbes as well as apoptoticcells. During maturation, phagosomes containing engulfed particlesfuse with various endosomal compartments through theaction of regulatory molecules on the phagosomal membrane. Inthis study, we performed a proteomic analysis of the membranefraction from latex bead-containing (LBC) phagosomes isolatedfrom macrophages. The profile, which comprised 546 proteins,suggests di… more
Date: November 25, 2008
Creator: Shui, Wenqing; Sheu, Leslie; Liu, Jun; Smart, Brian; Petzold, Christopher J.; Hsieh, Tsung-yen et al.
Partner: UNT Libraries Government Documents Department
open access

Electron-Cloud Build-Up Simulations for the FNAL Main Injector

Description: We present a summary on ongoing simulation results for the electron-cloud (EC) buildup in the context of the proposed FNAL Main Injector (MI) intensity upgrade effort [1]. Most of the results presented here are for the field-free region at the location of the retarding field analyzer (RFA) electron detector [2-4]. The primary input variable we exercise is the peak secondary electron yield (SEY) {delta}{sub max}, which we let vary in the range 1.2 {le} {delta}{sub max} {le} 1.7. By combining our… more
Date: August 25, 2008
Creator: Furman, Miguel .A.
Partner: UNT Libraries Government Documents Department
open access

Numerical Study of Coulomb Scattering Effects on Electron Beamfrom a Nano-Tip

Description: Nano-tips with high acceleration gradient around the emission surface have been proposed to generate high brightness beams. However, due to the small size of the tip, the charge density near the tip is very high even for a small number of electrons. The stochastic Coulomb scattering near the tip can degrade the beam quality and cause extra emittance growth and energy spread. In the paper, we present a numerical study of these effects using a direct relativistic N-body model. We found that emitt… more
Date: June 25, 2007
Creator: Qiang, Ji; Corlett, John N.; Lidia, Steven M.; Padmore, HowardA.; Wan, Weishi; Zholent, Andrew A. et al.
Partner: UNT Libraries Government Documents Department
open access

Performance of capillary discharge guided laser plasma wakefieldaccelerator

Description: A GeV-class laser-driven plasma-based wakefield acceleratorhas been realized at the Lawrence Berkeley National Laboratory (LBNL).The device consists of the 40TW high repetition rate Ti:sapphire LOASISlaser system at LBNL and a gas-filled capillary discharge waveguidedeveloped at Oxford University. The operation of the capillary dischargeguided laser plasma wakefield accelerator with a capillaryof 225 mu mdiameter and 33 mm in length was analyzed in detail. The input intensitydependence suggests… more
Date: June 25, 2007
Creator: Nakamura, Kei; Esarey, Eric; Geddes, Cameron G. R.; Gonsalves, Anthony J.; Leemans, Wim P.; Panasenko, Dmitriy et al.
Partner: UNT Libraries Government Documents Department
open access

PROGRESS IN BEAM FOCUSING AND COMPRESSION FOR WARM-DENSE MATTER EXPERIMENTS

Description: The Heavy-Ion Fusion Sciences Virtual National Laboratory is pursuing an approach to target heating experiments in the Warm Dense Matter regime, using spacecharge-dominated ion beams that are simultaneously longitudinally bunched and transversely focused. Longitudinal beam compression by large factors has beendemonstrated in the Neutralized Drift Compression Experiment (NDCX) with controlledramps and forced neutralization. Using an injected 30-mA K+ ion beam with initialkinetic energy 0.3 MeV, … more
Date: September 25, 2008
Creator: Seidl, P. A.; Anders, A.; Bieniosek, F. M.; Barnard, J. J.; Calanog, J.; Chen, A. X. et al.
Partner: UNT Libraries Government Documents Department
Back to Top of Screen