731 Matching Results

Search Results

Results: 1 - 24 next
open access

Equivalence of dipole correction and Coulomb cutoff techniques in supercell calculations

Description: Article on the equivalence of dipole correction and Coulomb cutoff techniques in supercell calculations. In this work, the authors compare the dipole correction and Coulomb cutoff methods under the same conditions in the framework of plane-wave based density-functional theory.
Date: June 3, 2008
Creator: Yu, Liping; Ranjan, Vivek; Lu, W.; Bernholc, Jerry & Buongiorno Nardelli, Marco
Partner: UNT College of Arts and Sciences
open access

Image-Based Modeling Reveals Dynamic Redistribution of DNA Damageinto Nuclear Sub-Domains

Description: Several proteins involved in the response to DNA doublestrand breaks (DSB) f orm microscopically visible nuclear domains, orfoci, after exposure to ionizing radiation. Radiation-induced foci (RIF)are believed to be located where DNA damage occurs. To test thisassumption, we analyzed the spatial distribution of 53BP1, phosphorylatedATM, and gammaH2AX RIF in cells irradiated with high linear energytransfer (LET) radiation and low LET. Since energy is randomly depositedalong high-LET particle path… more
Date: August 3, 2007
Creator: Costes Sylvain V.; Ponomarev, Artem; Chen, James L.; Nguyen, David; Cucinotta, Francis A. & Barcellos-Hoff, Mary Helen
Partner: UNT Libraries Government Documents Department
open access

Plan for Using Solar-Powered Jack Pumps to Sample Groundwater at the Nevada Test Site

Description: Groundwater is sampled from 39 monitoring wells on the Nevada Test Site (NTS) as part of the Routine Radiological Environmental Monitoring Program. Many of these wells were not designed or constructed for long-term groundwater monitoring. Some have extensive completion zones and others have obstructions such as pumps and tubing. The high-volume submersible pumps in some wells are unsuitable for long-term monitoring and result in large volumes of water that may have to be contained and character… more
Date: May 3, 2007
Creator: David Hudson, Charles Lohrstorfer, Bruce Hurley
Partner: UNT Libraries Government Documents Department
open access

How to Calculate Colourful Cross Sections Efficiently

Description: Different methods for the calculation of cross sections with many QCD particles are compared. To this end, CSW vertex rules, Berends-Giele recursion and Feynman-diagram based techniques are implemented as well as various methods for the treatment of colours and phase space integration. We find that typically there is only a small window of jet multiplicities, where the CSW technique has efficiencies comparable or better than both of the other two methods.
Date: September 3, 2008
Creator: Gleisberg, Tanju; Hoeche, Stefan & Krauss, Frank
Partner: UNT Libraries Government Documents Department
open access

In situ x-ray photoelectron spectroscopy studies of gas/solidinterfaces at near-ambient conditions

Description: X-ray photoelectron spectroscopy (XPS) is a quantitative, chemically specific technique with a probing depth of a few angstroms to a few nanometers. It is therefore ideally suited to investigate the chemical nature of the surfaces of catalysts. Because of the scattering of electrons by gas molecules, XPS is generally performed under vacuum conditions. However, for thermodynamic and/or kinetic reasons, the catalyst's chemical state observed under vacuum reaction conditions is not necessarily the… more
Date: December 3, 2007
Creator: Bluhm, Hendrik; Havecker, Michael; Knop-Gericke, Axel; Kiskinova,Maya; Schlogl, Robert & Salmeron, Miquel
Partner: UNT Libraries Government Documents Department
open access

Application of a pilot control banding tool for risk level assessment and control of nanoparticle exposures

Description: Control Banding (CB) strategies offer simplified solutions for controlling worker exposures to constituents that are found in the workplace in the absence of firm toxicological and exposure data. These strategies may be particularly useful in nanotechnology applications, considering the overwhelming level of uncertainty over what nanomaterials and nanotechnologies present as potential work-related health risks, what about these materials might lead to adverse toxicological activity, how risk re… more
Date: March 3, 2008
Creator: Paik, S Y; Zalk, D M & Swuste, P
Partner: UNT Libraries Government Documents Department
open access

Soft X-ray synchrotron radiation investigations of actinidematerials systems utilizing X-ray emission spectroscopy and resonantinelastic X-ray scattering

Description: Synchrotron radiation (SR) methods have been utilized with increasing frequency over the past several years to study topics in actinide science, ranging from those of a fundamental nature to those that address a specifically-targeted technical need. In particular, the emergence of microspectroscopic and fluorescence-based techniques have permitted investigations of actinide materials at sources of soft x-ray SR. Spectroscopic techniques with fluorescence-based detection are useful for actinide … more
Date: January 3, 2004
Creator: Shuh, D.K.; Butorin, S.M.; Guo, J.-H. & Nordgren, J.
Partner: UNT Libraries Government Documents Department
open access

Cfd Modeling Analysis of Mechanical Draft Cooling Tower

Description: Industrial processes use mechanical draft cooling towers (MDCT's) to dissipate waste heat by transferring heat from water to air via evaporative cooling, which causes air humidification. The Savannah River Site (SRS) has a MDCT consisting of four independent compartments called cells. Each cell has its own fan to help maximize heat transfer between ambient air and circulated water. The primary objective of the work is to conduct a parametric study for cooling tower performance under different f… more
Date: March 3, 2008
Creator: Lee, S.; Alfred Garrett, A.; James02 Bollinger, J. & Larry Koffman, L.
Partner: UNT Libraries Government Documents Department
open access

Theoretical investigations of two Si-based spintronic materials

Description: Two Si-based spintronic materials, a Mn-Si digital ferromagnetic heterostructure ({delta}-layer of Mn doped in Si) with defects and dilutely doped Mn{sub x}Si{sub 1-x} alloy are investigated using a density-functional based approach. We model the heterostructure and alloy with a supercell of 64 atoms and examine several configurations of the Mn atoms. We find that 25% substitutional defects without vacancies in the {delta} layer diminishes half metallicity of the DFH substantially. For the allo… more
Date: August 3, 2007
Creator: Fong, C Y; Snow, R; Shaughnessy, M; Pask, J E & Yang, L H
Partner: UNT Libraries Government Documents Department
open access

APTASENSORS FOR BIOSECURITY APPLICATIONS

Description: Nucleic acid aptamers have found steadily increased utility and application steadily over the last decade. In particular, aptamers have been touted as a valuable complement to and in some cases replacement for antibodies due to their structural and functional robustness as well as their ease in generation and synthesis. They are thus attractive for biosecurity applications, e.g. pathogen detection, and are especially well suited since their in vitro generation process does not require infection… more
Date: January 3, 2007
Creator: Fischer, N; Tarasow, T & Tok, J
Partner: UNT Libraries Government Documents Department
open access

Sub-diffraction-limited multilayer coatings for the 0.3-NA Micro-Exposure Tool for extreme ultraviolet lithography

Description: This manuscript discusses the multilayer coating results for the primary and secondary mirrors of the Micro Exposure Tool (MET): a 0.30-numerical aperture (NA) lithographic imaging system with 200 x 600 {micro}m{sup 2} field of view at the wafer plane, operating in the extreme ultraviolet (EUV) wavelength region. Mo/Si multilayers were deposited by DC-magnetron sputtering on large-area, curved MET camera substrates, and a velocity modulation technique was implemented to consistently achieve mul… more
Date: January 3, 2007
Creator: Soufli, R.; Hudyma, R. M.; Spiller, E.; Gullikson, E. M.; Schmidt, M. A.; Robinson, J. C. et al.
Partner: UNT Libraries Government Documents Department
open access

In-situ Spectroscopy of Water Oxidation at Ir Oxide Nanocluster Drivenby Visible TiOCr Charge-Transfer Chromophore in Mesoporous Silica

Description: An all-inorganic photocatalytic unit consisting of a binuclear TiOCr charge-transfer chromophore coupled to an Ir oxide nanocluster has been assembled on the pore surface of mesoporous silica AlMCM-41. In situ FT-Raman and EPR spectroscopy of an aqueous suspension of the resulting IrxOy-TiCr-AlMCM-41 powder reveal the formation of superoxide species when exciting the Ti(IV)OCr(III) --> Ti(III)OCr(IV) metal-to-metal charge-transfer chromophore with visible light. Use of H218O confirms that th… more
Date: June 3, 2008
Creator: Frei, Heinz; Han, Hongxian & Frei, Heinz
Partner: UNT Libraries Government Documents Department
open access

PREDICTION OF SURFACE SETTLEMENT DUE TO THE DISPLACEMENT OF SOFT ZONES

Description: In areas composed of coastal plain sediments, soft zones subjected to partial overburden may be present in the subsurface. During or after a seismic event, these soft zones may be compressed. The resulting displacement due to the deformation of the soft zones will propagate to the ground surface and cause the surface to settle. This paper presents a method to predict the settlement at the surface due to the propagation of the displacement from the soft zones. This method is performed by discret… more
Date: March 3, 2008
Creator: Li, W
Partner: UNT Libraries Government Documents Department
open access

TRWG developmental pathway for biospecimen-based assessment modalities

Description: The Translational Research Working Group (TRWG) was created as a national initiative to evaluate the current status of NCI's investment in translational research and envision its future. The TRWG conceptualized translational research as a set of six developmental processes or pathways focused on various clinical goals. One of those pathways describes the development of biospecimen-based assays that utilize biomarkers for the detection, diagnosis, prognosis, and assessment of response to cancer … more
Date: September 3, 2008
Creator: Group, Translational Research Working; Srivastava, Sudhir; Gray, Joe W.; Reid, Brian J.; Grad, Oren; Greenwood, Addison et al.
Partner: UNT Libraries Government Documents Department
open access

Software Engineering Processes Used to Develop the NIF Integrated Computer Control System

Description: We have developed a new target platform to study Laser Plasma Interaction in ignition-relevant condition at the Omega laser facility (LLE/Rochester)[1]. By shooting an interaction beam along the axis of a gas-filled hohlraum heated by up to 17 kJ of heater beam energy, we were able to create a millimeter-scale underdense uniform plasma at electron temperatures above 3 keV. Extensive Thomson scattering measurements allowed us to benchmark our hydrodynamic simulations performed with HYDRA [1]. As… more
Date: October 3, 2007
Creator: Ludwigsen, A P; Carey, R W; Demaret, R D; Lagin, L J; Reddi, U P & Van Arsdall, P J
Partner: UNT Libraries Government Documents Department
open access

Energy and visual comfort performance of electrochromic windowswith overhangs

Description: DOE-2 building energy simulations were conducted to determine if there were practical architectural and control strategy solutions that would enable electrochromic (EC) windows to significantly improve visual comfort without eroding energy-efficiency benefits. EC windows were combined with overhangs since opaque overhangs provide protection from direct sun which EC windows are unable to do alone. The window wall was divided into an upper and lower aperture so that various combinations of overha… more
Date: November 3, 2005
Creator: Lee, E.S. & Tavil, A.
Partner: UNT Libraries Government Documents Department
open access

Estimating solar access of typical residential rooftops: A case study in San Jose, CA

Description: Shadows cast by trees and buildings can limit the solar access of rooftop solar-energy systems, including photovoltaic panels and thermal collectors. This study characterizes rooftop shading in a residential neighborhood of San Jose, CA, one of four regions analyzed in a wider study of the solar access of California homes.High-resolution orthophotos and LiDAR (Light Detection And Ranging) measurements of surface height were used to create a digital elevation model of all trees and buildings in … more
Date: March 3, 2008
Creator: Levinson, Ronnen M.; Gupta, Smita; Akbari, Hashem & Pomerantz, Melvin
Partner: UNT Libraries Government Documents Department
open access

Manifest Ultraviolet Behavior in the Three-Loop Four-Point Amplitude of N=8 Supergravity

Description: Using the method of maximal cuts, we obtain a form of the three-loop four-point scattering amplitude of N = 8 supergravity in which all ultraviolet cancellations are made manifest. The Feynman loop integrals that appear have a graphical representation with only cubic vertices, and numerator factors that are quadratic in the loop momenta, rather than quartic as in the previous form. This quadratic behavior reflects cancellations beyond those required for finiteness, and matches the quadratic beh… more
Date: September 3, 2008
Creator: Bern, Z.; Carrasco, J. J. M.; Dixon, L. J.; Johansson, H. & Roiban, R.
Partner: UNT Libraries Government Documents Department
open access

Microwave Transmission Measurements of the Electron Cloud Density In The Positron Ring of PEP-II

Description: Clouds of electrons in the vacuum chambers of accelerators of positively charged particle beams present a serious limitation for operation of these machines at high currents. Because of the size of these accelerators, it is difficult to probe the low energy electron clouds over substantial lengths of the beam pipe. We applied a novel technique to directly measure the electron cloud density via the phase shift induced in a TE wave which is independently excited and transmitted over a straight se… more
Date: July 3, 2008
Creator: Pivi, M. T. F.; Krasnykh, A. K; Byrd, J.; Santis, S.De; Sonnad, K. G.; Caspers, F. et al.
Partner: UNT Libraries Government Documents Department
open access

Translating the cancer genome: Going beyond p values

Description: Cancer cells are endowed with diverse biological capabilities driven by myriad inherited and somatic genetic and epigenetic aberrations that commandeer key cancer-relevant pathways. Efforts to elucidate these aberrations began with Boveri's hypothesis of aberrant mitoses causing cancer and continue today with a suite of powerful high-resolution technologies that enable detailed catalogues of genomic aberrations and epigenomic modifications. Tomorrow will likely bring the complete atlas of rever… more
Date: April 3, 2008
Creator: Chin, Lynda; Chin, Lynda & Gray, Joe W.
Partner: UNT Libraries Government Documents Department
open access

An Investigation of the Effect of Graphite Degradation on the Irreversible Capacity in Lithium-ion Cells

Description: The effect of surface structural damage on graphitic anodes, commonly observed in tested Li-ion cells, was investigated. Similar surface structural disorder was artificially induced in Mag-10 synthetic graphite anodes using argon-ion sputtering. Raman microscopy, scanning electron microscopy (SEM) and Brunauer Emmett Teller (BET) measurements confirmed that Ar-ion sputtered Mag-10 electrodes display similar degree of surface degradation as the anodes from tested Li-ion cells. Artificially modif… more
Date: March 3, 2008
Creator: Stevenson, Cynthia; Hardwick, Laurence J.; Marcinek, Marek; Beer, Leanne; Kerr, John B. & Kostecki, Robert
Partner: UNT Libraries Government Documents Department
open access

Tomographic wavefront correction for the LSST

Description: The Large Synoptic Survey Telescope (LSST) is a three mirror modified Paul-Baker design with an 8.4m primary, a 3.4m secondary, and a 5.0m tertiary followed by a 3-element refractive corrector producing a 3.5 degree field of view. This design produces image diameters of <0.3 arcsecond 80% encircled energy over its full field of view. The image quality of this design is sufficient to ensure that the final images produced by the telescope will be limited by the atmospheric seeing at an excelle… more
Date: May 3, 2006
Creator: Phillion, D. W.; Olivier, S. S.; Baker, K.; Seppala, L. & Hvisc, S.
Partner: UNT Libraries Government Documents Department
Back to Top of Screen