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On The Reproducibility of Seasonal Land-surface Climate

Description: The sensitivity of the continental seasonal climate to initial conditions is estimated from an ensemble of decadal simulations of an atmospheric general circulation model with the same specifications of radiative forcings and monthly ocean boundary conditions, but with different initial states of atmosphere and land. As measures of the ''reproducibility'' of continental climate for different initial conditions, spatio-temporal correlations are computed across paired realizations of eleven model… more
Date: October 22, 2004
Creator: Phillips, T J
Partner: UNT Libraries Government Documents Department
open access

Dynamic Load Balancing of Parallel Monte Carlo Transport Calculations

Description: The performance of parallel Monte Carlo transport calculations which use both spatial and particle parallelism is increased by dynamically assigning processors to the most worked domains. Since the particle work load varies over the course of the simulation, this algorithm determines each cycle if dynamic load balancing would speed up the calculation. If load balancing is required, a small number of particle communications are initiated in order to achieve load balance. This method has decrease… more
Date: December 22, 2004
Creator: O'Brien, M; Taylor, J & Procassini, R
Partner: UNT Libraries Government Documents Department
open access

Raman Scattering of Azafullerene C48N12

Description: Raman scattering activities and Raman-active frequencies are reported for the minimum energy structure of azafullerene C{sub 48}N{sub 12} at the B3LYP/6-31G* level of theory. Analysis of the vibrational spectrum shows that the most intense IR and Raman bands are those associated with C-C vibrations, and that strong IR and Raman C-N vibrations occur below 1400 cm{sup -1}. Together with the recently reported infrared, optical absorption and x-ray spectroscopies, a complete identification of this … more
Date: September 22, 2004
Creator: Manaa, M R
Partner: UNT Libraries Government Documents Department
open access

Cable Design for Fast Ramped Superconducting Magnets (Cos-θ Design).

Description: The new heavy ion synchrotron facility proposed by GSI will have two superconducting magnet rings in the same tunnel, with rigidities of 300 T-m and 100 T-m. Fast ramp times are needed, which can cause significant problems for the magnets, particularly in the areas of ac loss and magnetic field distortion. The development of the low loss Rutherford cable that can be used is described, together with a novel insulation scheme designed to promote efficient cooling. Measurements of contact resistan… more
Date: March 22, 2004
Creator: Ghosh, A.
Partner: UNT Libraries Government Documents Department
open access

Resolving the Nature of the LMC Microlensing Event LMC-5

Description: The authors present the results from an analysis of Hubble Space Telescope High Resolution Camera data for the Large Magellanic Cloud microlensing event MACHO-LMC-5. By determining the parallax and proper motion of this object they find that the lens is an M dwarf star at a distance of 578{sub -53}{sup +65}pc with a proper motion of 21.39 {+-} 0.04 mas/yr. Based on the kinematics and location of this star is it more likely to be part of the Galactic thick disk than thin disk population. They co… more
Date: April 22, 2004
Creator: Drake, A J; Cook, K H & Keller, S C
Partner: UNT Libraries Government Documents Department
open access

Concurrent Multiscale Simulation at Finite Temperature: Coarse-Grained Molecular Dynamics

Description: With the advent of nanotechnology, predictive simulations of nanoscale systems have become in great demand. In some cases nanoscale systems can be simulated directly at the level of atoms. The atomistic techniques used range from models based on a quantum mechanical treatment of the electronic bonds to those based on more empirical descriptions of the interatomic forces. In many cases, however, even nanoscale systems are too big for a purely atomistic approach, typically because the nanoscale d… more
Date: January 22, 2004
Creator: Rudd, R E
Partner: UNT Libraries Government Documents Department
open access

Evaluation Of Microdosing Strategies For Studies In Preclinical Drug Development: Demonstration Of Linear Pharmacokinetics In Dogs Of A Nucleoside Analogue Over A 50-Fold Dose Range

Description: The technique of accelerator mass spectrometry (AMS) was validated successfully and utilized to study the pharmacokinetics and disposition in dogs of a preclinical drug candidate (Compound A), after oral and intravenous administration. The primary objective of this study was to examine whether Compound A displayed linear kinetics across sub-pharmacological (microdose) and pharmacological dose ranges in an animal model, prior to initiation of a human microdose study. The AMS-derived disposition … more
Date: April 22, 2004
Creator: Sandhu, P; Vogel, J S; Rose, M J; Ubick, E A; Brunner, J E; Wallace, M A et al.
Partner: UNT Libraries Government Documents Department
open access

Little Supersymmetry and the Supersymmetric Little Hierarchy Problem

Description: The current experimental lower bound on the Higgs mass significantly restricts the allowed parameter space in most realistic supersymmetric models, with the consequence that these models exhibit significant fine-tuning. We propose a solution to this `supersymmetric little hierarchy problem'. We consider scenarios where the stop masses are relatively heavy - in the 500 GeV to a TeV range. Radiative stability of the Higgs soft mass against quantum corrections from the top quark Yukawa coupling is… more
Date: April 22, 2004
Creator: Birkedal, Andreas; Chacko, Z. & Gaillard, Mary K.
Partner: UNT Libraries Government Documents Department
open access

Broadband THz response of a resonantly excited high-densityexciton gas

Description: The density-driven crossover of electron-hole pairs frominsulating to conducting states is observed via the internal 1s-2pexciton resonance. Decreasing interparticle distance induces strongshifts and broadening, and ultimately the disappearance of the excitonicresonance.
Date: November 22, 2004
Creator: Huber, Rupert; Kaindl, Robert A.; Schmid, Benjamin A. & Chemla,Daniel S.
Partner: UNT Libraries Government Documents Department
open access

Secure password-based authenticated key exchange for web services

Description: This paper discusses an implementation of an authenticated key-exchange method rendered on message primitives defined in the WS-Trust and WS-SecureConversation specifications. This IEEE-specified cryptographic method (AuthA) is proven-secure for password-based authentication and key exchange, while the WS-Trust and WS-Secure Conversation are emerging Web Services Security specifications that extend the WS-Security specification. A prototype of the presented protocol is integrated in the WSRF-co… more
Date: November 22, 2004
Creator: Liang, Fang; Meder, Samuel; Chevassut, Olivier & Siebenlist, Frank
Partner: UNT Libraries Government Documents Department
open access

Search for higgs, leptoquarks, and exotics at Tevatron

Description: This paper reviews some of the most recent results from the CDF and D0 experiments on the searches for Standard Model and Non-Standard Model Higgs bosons, and other new phenomena at the Tevatron. Both experiments examine data from proton anti-proton collision at {radical}s = 1.96 TeV, of integrated luminosity {approx} 200 pb{sup -1} (per experiment), to search for Higgs predicted in the Standard Model and beyond Standard Model, supersymmetric particles in the Gauge Mediated Symmetry Breaking sc… more
Date: June 22, 2004
Creator: Wang, Song Ming
Partner: UNT Libraries Government Documents Department
open access

Colloid Formation at Waste Plume Fronts

Description: Highly saline and caustic tank waste solutions containing radionuclides and toxic metals have leaked into sediments at U. S. Department of Energy (DOE) facilities such as the Hanford Site (Washington State). Colloid transport is frequently invoked to explain migration of radionuclides and metals in the subsurface. To understand colloid formation during interactions between highly reactive fluids and sediments and its impact on contaminant transport, we simulated tank waste solution (TWS) leakag… more
Date: May 22, 2004
Creator: Wan, Jiamin; Tokunaga, Tetsu K.; Saiz, Eduardo; Larsen, Joern T.; Zheng, Zuoping & Couture, Rex A.
Partner: UNT Libraries Government Documents Department
open access

Laser triggered injection of electrons in a laser wakefield accelerator with the colliding pulse method

Description: An injection scheme for a laser wakefield accelerator that employs a counter propagating laser (colliding with the drive laser pulse, used to generate a plasma wake) is discussed. The threshold laser intensity for electron injection into the wakefield was analyzed using a heuristic model based on phase-space island overlap. Analysis shows that the injection can be performed using modest counter propagating laser intensity a{sub 1} < 0.5 for a drive laser intensity of a{sub 0} = 1.0. Prelimin… more
Date: October 22, 2004
Creator: Nakamura, K.; Fubiani, G.; Geddes, C. G. R.; Michel, P.; van Tilborg, J.; Toth, C. et al.
Partner: UNT Libraries Government Documents Department
open access

Prospects in CP violation measurements at the Tevatron Collider

Description: The Fermilab Tevatron Collider is currently the most copious source of b-hadrons, thanks to the large b{bar b} production cross-section in 1.96 TeV p{bar p} collisions. Recent detector upgrades allow for a wide range of CP violation and flavor-mixing measurements that are fully competitive (direct asymmetries in self-tagging modes) or complementary (asymmetries of B{sub s} and b-baryons decays) with B-factories. In this paper we review some recent CP violation results from the D0 and CDF II Col… more
Date: June 22, 2004
Creator: Tonelli, Diego
Partner: UNT Libraries Government Documents Department
open access

A prediction for |U{sub e3}| from patterns in the charged lepton spectra

Description: It is shown that empirical relations between the charged lepton spectra and the quark spectra together with a bimaximal or near bimaximal neutrino mixing matrix necessarily imply that there is a contribution to |U{sub e3}| given by {theta}{sub C}/ 3{radical}2 {approx} {radical}(m{sub e}/2m{sub {mu}}) {approx} 0.052, where {theta}{sub C}is the Cabibbo angle. This prediction could be tested in the near future reactor experiments. The charged lepton mixing also generates a less robust prediction f… more
Date: September 22, 2004
Creator: Ferrandis, Javier & Pakvasa, Sandip
Partner: UNT Libraries Government Documents Department
open access

Ground Test Facility for Propulsion and Power Modes of Nuclear Engine Operation

Description: Existing DOE Ground Test Facilities have not been used to support nuclear propulsion testing since the Rover/NERVA programs of the 1960's. Unlike the Rover/NERVA programs, DOE Ground Test facilities for space exploration enabling nuclear technologies can no longer be vented to the open atmosphere. The optimal selection of DOE facilities and accompanying modifications for confinement and treatment of exhaust gases will permit the safe testing of NASA Nuclear Propulsion and Power devices involvin… more
Date: November 22, 2004
Creator: Michael, WILLIAMS
Partner: UNT Libraries Government Documents Department
open access

Using an Active Pixel Sensor In A Vertex Detector

Description: Research has shown that Active Pixel CMOS sensors can detect charged particles. We have been studying whether this process can be used in a collider environment. In particular, we studied the effect of radiation with 55 MeV protons. These results show that a fluence of about 2 x 10{sup 12} protons/cm{sup 2} reduces the signal by a factor of two while the noise increases by 25%. A measurement 6 months after exposure shows that the silicon lattice naturally repairs itself. Heating the silicon to … more
Date: April 22, 2004
Creator: Matis, Howard S.; Bieser, Fred; Chen, Yandong; Gareus, Robin; Kleinfelder, Stuart; Oldenburg, Markus et al.
Partner: UNT Libraries Government Documents Department
open access

Utilizing Strong Tight Intermodal Waste Packaging to Meet Accelerated Cleanup Goals at The Savannah River Site

Description: In support of the accelerated cleanup challenge, personnel at the Savannah River Site have been working diligently to identify and acquire cost-effective waste containers that can be used to package a voluminous amount of low level radioactive waste that needs to be disposed. In so doing, personnel have transformed their paradigm in packaging low level radioactive waste in traditional 45-cubic-foot and 90-cubic-foot containers and utilizing refurbished intermodal containers instead. The transit… more
Date: January 22, 2004
Creator: Kinney, JosephC.
Partner: UNT Libraries Government Documents Department
open access

Coherent transition radiation from a laser wakefield accelerator as an electron bunch diagnostic

Description: The observation and modeling of coherent transition radiation from femtosecond laser accelerated electron bunches is discussed. The coherent transition radiation, scaling quadratically with bunch charge, is generated as the electrons transit the plasma-vacuum boundary. Due to the limited transverse radius of the plasma boundary, diffraction effects will strongly modify the angular distribution and the total energy radiated is reduced compared to an infinite transverse boundary. The multi-nC ele… more
Date: October 22, 2004
Creator: van Tilborg, J.; Geddes, C. G. R.; Toth, C.; Esarey, E.; Schroeder, C. B.; Martin, M. C. et al.
Partner: UNT Libraries Government Documents Department
open access

Domain-size-dependent exchange bias in Co/LaFeO3

Description: X-ray microscopy using magnetic linear dichroism of a zero-field-grown, multi-domain Co/LaFeO{sub 3} ferromagnet/antiferromagnet sample shows a local exchange bias of random direction and magnitude. A statistical analysis of the local bias of individual, micron-size magnetic domains demonstrates an increasing bias field with decreasing domain size as expected for a random distribution of pinned, uncompensated spins, which are believed to mediate the interface coupling. A linear dependence with … more
Date: September 22, 2004
Creator: Scholl, A.; Nolting, F.; Seo, J.W.; Ohldag, H.; Stohr, J.; Raoux,S. et al.
Partner: UNT Libraries Government Documents Department
open access

Comparison of experimental data and 3D simulations of ion beam neutralization from the neutralized transport experiment

Description: The Neutralized Transport Experiment (NTX) at Lawrence Berkeley National Laboratory has been designed to study the final focus and neutralization of high perveance ion beams for applications in heavy ion fusion (HIF) and high energy density physics (HEDP) experiments. Pre-formed plasmas in the last meter before the target of the scaled experiment provide a source of electrons which neutralize the ion current and prevent the space-charge induced spreading of the beam spot. NTX physics issues are… more
Date: September 22, 2004
Creator: Thoma, C.; Welch, D. R.; Yu, S. S.; Henestroza, E.; Roy, P. K.; Eylon, S. et al.
Partner: UNT Libraries Government Documents Department
open access

D-meson enhancement in pp collisions at the LHC due to nonlinear gluon evolution

Description: When nonlinear effects on the gluon evolution are included with constraints from HERA, the gluon distribution in the free proton is enhanced at low momentum fractions, x {approx}< 0.01, and low scales, Q{sup 2} {approx}< 10 GeV{sup 2}, relative to standard, DGLAP-evolved, gluon distributions. Consequently, such gluon distributions can enhance charm production in pp collisions at center of mass energy 14 TeV by up to a factor of five at midrapidity, y {approx} 0, and transverse momentum p{… more
Date: August 22, 2004
Creator: Dainese, A.; Vogt, R.; Bondila, M.; Eskola, K.J. & Kolhinen, V.J.
Partner: UNT Libraries Government Documents Department
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