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The History Engine: Doing History with Digital Tools

Description: Article on the History Engine Project, an online archive consisting of thousands of narratives written and contributed by undergraduates.
Date: September 9, 2009
Creator: Nelson, Robert K.; Nesbit, Scott & Torget, Andrew J., 1978-
Partner: UNT College of Arts and Sciences
open access

Theory and Fluid Simulations of Boundary Plasma Fluctuations

Description: Theoretical and computational investigations are presented of boundary plasma microturbulence that take into account important effects of the geometry of diverted tokamaks--in particular, the effect of x-point magnetic shear and the termination of field lines on divertor plates. We first generalize our previous 'heuristic boundary condition' which describes, in a lumped model, the closure of currents in the vicinity of the x-point region to encompass three current-closure mechanisms. We then us… more
Date: January 9, 2007
Creator: Cohen, R. H.; LaBombard, B.; LoDestro, L. L.; Rognlien, T. D.; Ryutov, D. D.; Terry, J. L. et al.
Partner: UNT Libraries Government Documents Department
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ENCAPSULATION OF PALLADIUM IN POROUS WALL HOLLOW GLASS MICROSPHERES

Description: A new encapsulation method was investigated in an attempt to develop an improved palladium packing material for hydrogen isotope separation. Porous wall hollow glass microspheres (PWHGMs) were produced by using a flame former, heat treating and acid leaching. The PWHGMs were then filled with palladium salt using a soak-and-dry process. The palladium salt was reduced at high temperature to leave palladium inside the microspheres.
Date: April 9, 2008
Creator: Heung, L.; George Wicks, G. & Ray Schumacher, R.
Partner: UNT Libraries Government Documents Department
open access

New Results on Leptonic B Meson Decays at BaBar

Description: The authors present selected new results on leptonic B meson decays from the BABAR experiment: searches for the decays B{sup 0} {yields} {ell}{sup +}{ell}{sup -}, B{sup +} {yields} {ell}{sup +}{nu} and B{sup 0} {yields} {ell}{sup +}{tau}{sup -}, and B {yields} K{nu}{bar {nu}}, where {ell} = e or {mu}. They observe no evidence for these decays and set upper limits on their branching fractions.
Date: June 9, 2008
Creator: Kim, Hojeong
Partner: UNT Libraries Government Documents Department
open access

SYNTHESIS OF THE FULLY PROTECTED PHOSPHORAMIDITE OF THE BENZENE-DNA ADDUCT, N2- (4-HYDROXYPHENYL)-2'-DEOXYGUANOSINE AND INCORPORATION OF THE LATER INTO DNA OLIGOMERS

Description: N2-(4-Hydroxyphenyl)-2'-deoxyguanosine-5'-O-DMT-3'-phosphoramidite has been synthesized and used to incorporate the N2-(4-hydroxyphenyl)-2'-dG (N2-4-HOPh-dG) into DNA, using solid-state synthesis technology. The key step to obtaining the xenonucleoside is a palladium (Xantphos-chelated) catalyzed N2-arylation (Buchwald-Hartwig reaction) of a fully protected 2'-deoxyguanosine derivative by 4-isobutyryloxybromobenzene. The reaction proceeded in good yield and the adduct was converted to the requi… more
Date: June 9, 2008
Creator: Chenna, Ahmed; Gupta, Ramesh C.; Bonala, Radha R.; Johnson, Francis & Huang, Bo
Partner: UNT Libraries Government Documents Department
open access

Behavior of Repeating Earthquake Sequences in Central California and the Implications for Subsurface Fault Creep

Description: Repeating earthquakes (REs) are sequences of events that have nearly identical waveforms and are interpreted to represent fault asperities driven to failure by loading from aseismic creep on the surrounding fault surface at depth. We investigate the occurrence of these REs along faults in central California to determine which faults exhibit creep and the spatio-temporal distribution of this creep. At the juncture of the San Andreas and southern Calaveras-Paicines faults, both faults as well as … more
Date: July 9, 2007
Creator: Templeton, D C; Nadeau, R & Burgmann, R
Partner: UNT Libraries Government Documents Department
open access

Structure and Reactions of Carbon and Hydrogen on Ru(0001): A Scanning Tunneling Microscopy Study

Description: The interaction between carbon and hydrogen atoms on a Ru(0001) surface was studied using scanning tunneling microscopy (STM), Density Functional Theory (DFT) and STM image calculations. Formation of CH species by reaction between adsorbed H and C was observed to occur readily at 100 K. When the coverage of H increased new complexes of the form CH+nH (n = 1, 2 and 3) were observed. These complexes, never observed before, might be precursors for further hydrogenation reactions. DFT analysis reve… more
Date: September 9, 2008
Creator: Shimizu, Tomoko K.; Mugarza, Aitor; Cerda, Jorge & Salmeron, Miquel
Partner: UNT Libraries Government Documents Department
open access

Thermodynamic ground states of platinum metal nitrides

Description: We have systematically studied the thermodynamic stabilities of various phases of the nitrides of the platinum metal elements using density functional theory. We show that for the nitrides of Rh, Pd, Ir and Pt two new crystal structures, in which the metal ions occupy simple tetragonal lattice sites, have lower formation enthalpies at ambient conditions than any previously proposed structures. The region of stability can extend up to 17 GPa for PtN{sub 2}. Furthermore, we show that according to… more
Date: October 9, 2007
Creator: Aberg, D; Sadigh, B; Crowhurst, J & Goncharov, A
Partner: UNT Libraries Government Documents Department
open access

Light-Front Holography and QCD Hadronization at the Amplitude Level

Description: Light-front holography allows hadronic amplitudes in the AdS/QCD fifth dimension to be mapped to frame-independent light-front wavefunctions of hadrons in physical space-time, thus providing a relativistic description of hadrons at the amplitude level. The AdS coordinate z is identified with an invariant light-front coordinate {zeta} which separates the dynamics of quark and gluon binding from the kinematics of constituent spin and internal orbital angular momentum. The result is a single-varia… more
Date: January 9, 2009
Creator: Brodsky, Stanley J. & de Teramond, Guy F.
Partner: UNT Libraries Government Documents Department
open access

Silver ion mediated shape control of platinum nanoparticles: Removal of silver by selective etching leads to increased catalytic activity

Description: A procedure has been developed for the selective etching of Ag from Pt nanoparticles of well-defined shape, resulting in the formation of elementally-pure Pt cubes, cuboctahedra, or octahedra, with a largest vertex-to-vertex distance of {approx}9.5 nm from Ag-modified Pt nanoparticles. A nitric acid etching process was applied Pt nanoparticles supported on mesoporous silica, as well as nanoparticles dispersed in aqueous solution. The characterization of the silica-supported particles by XRD, TE… more
Date: January 9, 2008
Creator: Grass, Michael E.; Yue, Yao; Habas, Susan E.; Rioux, Robert M.; Teall, Chelsea I. & Somorjai, G.A.
Partner: UNT Libraries Government Documents Department
open access

The US Support program to IAEA Safeguards - 2008

Description: The U.S. Support Program to IAEA Safeguards (USSP) was established in 1977 to provide technical assistance to the IAEA Department of Safeguards. Since that time the U.S. Department of State has provided funding of over $200 million and over 900 tasks have been completed by USSP contractors on behalf of the KEA. The USSP is directed by a U.S. interagency subcommittee known as the Subgroup on Safeguards Technical Support (SSTS) and is managed by the International Safeguards Project Office (ISPO) … more
Date: June 9, 2008
Creator: Pepper,S.
Partner: UNT Libraries Government Documents Department
open access

Dynamic versus Static Hadronic Structure Functions

Description: 'Static' structure functions are the probabilistic distributions computed from the square of the light-front wavefunctions of the target hadron. In contrast, the 'dynamic' structure functions measured in deep inelastic lepton-hadron scattering include the effects of rescattering associated with the Wilson line. Initial- and final-state rescattering, neglected in the parton model, can have a profound effect in QCD hard-scattering reactions, producing single-spin asymmetries, diffractive deep ine… more
Date: January 9, 2009
Creator: Brodsky, Stanley J.
Partner: UNT Libraries Government Documents Department
open access

An Extensible Open-Source Compiler Infrastructure for Testing

Description: Testing forms a critical part of the development process for large-scale software, and there is growing need for automated tools that can read, represent, analyze, and transform the application's source code to help carry out testing tasks. However, the support required to compile applications written in common general purpose languages is generally inaccessible to the testing research community. In this paper, we report on an extensible, open-source compiler infrastructure called ROSE, which i… more
Date: December 9, 2005
Creator: Quinlan, D; Ur, S & Vuduc, R
Partner: UNT Libraries Government Documents Department
open access

Photofragment Coincidence Imaging of Small I- (H2O)n Clusters Excited to the Charge-transfer-to-solvent State

Description: The photodissociation dynamics of small I{sup -}(H{sub 2}O){sub n} (n = 2-5) clusters excited to their charge-transfer-to-solvent (CTTS) states have been studied using photofragment coincidence imaging. Upon excitation to the CTTS state, two photodissociation channels were observed. The major channel ({approx}90%) is a 2-body process forming neutral I + (H{sub 2}O){sub n} photofragments, and the minor channel is a 3-body process forming I + (H{sub 2}O){sub n-1} + H{sub 2}O fragments. Both proce… more
Date: November 9, 2005
Creator: Neumark, D. E. Szpunar, K. E. Kautzman, A. E. Faulhaber, and D. M.; Kautzman, K.E.; Faulhaber, A.E. & Faulhaber, A.E.
Partner: UNT Libraries Government Documents Department
open access

Gryrokinetic Simulations of ETG and ITG Turbulence

Description: No Description Available.
Date: January 9, 2007
Creator: Dimits, A. M.; Nevins, W. M.; Shumaker, D. E.; Hammett, G. W.; Dannert, T.; Jenko, F. et al.
Partner: UNT Libraries Government Documents Department
open access

Ionization By Impact Electrons in Solids: Electron Mean Free Path Fitted Over A Wide Energy Range

Description: We propose a simple formula for fitting the electron mean free paths in solids both at high and at low electron energies. The free-electron-gas approximation used for predicting electron mean free paths is no longer valid at low energies (E < 50 eV), as the band structure effects become significant at those energies. Therefore we include the results of the band structure calculations in our fit. Finally, we apply the fit to 9 elements and 2 compounds.
Date: June 9, 2005
Creator: Ziaja, B; London, R A & Hajdu, J
Partner: UNT Libraries Government Documents Department
open access

Accelerator mass spectrometry of actinides

Description: No Description Available.
Date: June 9, 2005
Creator: Marchetti, A. A.; Brown, T. A.; Cox, C. C.; Hamilton, T. F. & Martinelli, R. E.
Partner: UNT Libraries Government Documents Department
open access

EFFECTIVE DOSIMETRIC HALF LIFE OF CESIUM 137 SOIL CONTAMINATION

Description: In the early 1960s, an area of privately-owned swamp adjacent to the US Department of Energy's Savannah River Site (SRS), known as Creek Plantation, was contaminated by site operations. Studies conducted in 1974 estimated that approximately 925 GBq of {sup 137}Cs was deposited in the swamp. Subsequently, a series of surveys--composed of 52 monitoring locations--was initiated to characterize and trend the contaminated environment. The annual, potential, maximum doses to a hypothetical hunter wer… more
Date: January 9, 2008
Creator: Jannik, T; P Fledderman, P & Michael Paller, M
Partner: UNT Libraries Government Documents Department
open access

X-ray streak camera temporal resolution improvement using a longitudinal time-dependent field

Description: X-ray streak cameras (XSC) have been known to be one of the fastest detectors forultrafast X-ray science. A number of applications in material science, biochemistry, accelerator physics, require sub-picosecond resolution to study new phenomena. Inthis paper, we report on a new method which can potentially improve the temporal resolution of a streak camera down to 100 femtoseconds. This method uses a time-dependent acceleration field to lengthen the photoelectron bunch, significantlyimproving th… more
Date: May 9, 2008
Creator: Qiang, Ji; Qiang, J.; Byrd, J.M.; Feng, J. & Huang, G.
Partner: UNT Libraries Government Documents Department
open access

Characterization of a mixed salt of 1-hydroxy-pyridin-2-one Pu(IV)complexes

Description: Most expert analyses of the projected world energy needs show utilization of nuclear energy will be essential for the next few decades, and hence the need to support this technology grows. But as one measure of the supporting science base of this field, as of December 2006, only 25 Pu containing structures were in the Cambridge Structural Database, as compared to 21,807 for Fe. A comparison of the rate of addition to this knowledge base reveals that approximately 500 Fe structures are registere… more
Date: January 9, 2007
Creator: Gorden, Anne E.V.; Xu, Jide; Szigethy, Geza; Oliver, Allen; Shuh,David K. & Raymond, Kenneth N.
Partner: UNT Libraries Government Documents Department
open access

Ion Exclusion by Sub 2-nm Carbon Nanotube Pores

Description: Carbon nanotubes offer an outstanding platform for studying molecular transport at nanoscale, and have become promising materials for nanofluidics and membrane technology due to their unique combination of physical, chemical, mechanical, and electronic properties. In particular, both simulations and experiments have proved that fluid flow through carbon nanotubes of nanometer size diameter is exceptionally fast compared to what continuum hydrodynamic theories would predict when applied on this … more
Date: April 9, 2008
Creator: Fornasiero, F; Park, H G; Holt, J K; Stadermann, M; Grigoropoulos, C P; Noy, A et al.
Partner: UNT Libraries Government Documents Department
open access

Azimuthal HBT and Transverse Momentum Fluctuations from CERES.

Description: CERES is a dilepton experiment at the CERN SPS, known for its observation of enhanced production of low mass efe- pairs in collisions between heavy nuclei [1]. The upgrade of CERES in 1997-1998 by a radial Time Projection Chamber (TPC) [2] allowed to improve the momentum resolution and the particle identification capability while retaining the cylindrical symmetry. The upgraded experiment is shown in Fig. 1. The upgrade also extended the sensitivity of CERES to hadrons and made possible results… more
Date: July 9, 2007
Creator: Miskowiec,D.; Rehak, P. & al., et
Partner: UNT Libraries Government Documents Department
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