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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

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

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

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

Explosively driven facture and fragmentation of metal cylinders and rings

Description: Cylinders and rings fabricated from AerMet{reg_sign} 100 alloy and AISI 1018 steel have been explosively driven to fragmentation in order to determine the fracture strains for these materials under plane strain and uniaxial stress conditions. The phenomena associated with the dynamic expansion and subsequent break up of the cylinders are monitored with high-speed diagnostics. In addition, complementary experiments are performed in which fragments from the explosively driven cylinder are recover… more
Date: January 3, 2007
Creator: Goto, D; Becker, R C; Orzechowski, T J; Springer, H K; Sunwoo, A J & Syn, C K
Partner: UNT Libraries Government Documents Department
open access

Fuel Effects on a Low-Swirl Injector for Lean Premixed Gas Turbines

Description: Laboratory experiments have been conducted to investigate the fuel effects on the turbulent premixed flames produced by a gas turbine low-swirl injector (LSI). The lean-blow off limits and flame emissions for seven diluted and undiluted hydrocarbon and hydrogen fuels show that the LSI is capable of supporting stable flames that emit < 5 ppm NO{sub x} ({at} 15% O{sub 2}). Analysis of the velocity statistics shows that the non-reacting and reacting flowfields of the LSI exhibit similarity feat… more
Date: December 3, 2007
Creator: Littlejohn, David; Littlejohn, David & Cheng, R.K.
Partner: UNT Libraries Government Documents Department
open access

High power impulse magnetron sputtering: Current-voltage-timecharacteristics indicate the onset of sustained self-sputtering

Description: The commonly used current-voltage characteristics are foundinadequate for describing the pulsed nature of the high power impulsemagnetron sputtering (HIPIMS) discharge, rather, the description needs tobe expanded to current-voltage-time characteristics for each initial gaspressure. Using different target materials (Cu, Ti, Nb, C, W, Al, Cr) anda pulsed constant-voltage supply it is shown that the HIPIMS dischargestypically exhibit an initial pressure dependent current peak followed bya second p… more
Date: August 3, 2007
Creator: Anders, Andre; Andersson, Joakim & Ehiasarian, Arutiun
Partner: UNT Libraries Government Documents Department
open access

Internal Alignment of the SLD Vertex Detector

Description: The tracking resolution and vertex finding capabilities of the SLD experiment depended upon a precise knowledge of the location and orientation of the elements of the SLD pixel vertex detector (VXD3) in 3D space. At the heart of the procedure described here to align the 96 CCDs is the matrix inversion technique of singular value decomposition (SVD). This tool was employed to unfold the detector geometry corrections from the track data in the VXD3. The algorithm was adapted to perform an optimal… more
Date: December 3, 2007
Creator: Jackson, D. J.; Wickens, F. J. & Su, D.
Partner: UNT Libraries Government Documents Department
open access

Local Area Signal-to-Noise Ratio (LASNR) algorithm for Image Segmentation

Description: Many automated image-based applications have need of finding small spots in a variably noisy image. For humans, it is relatively easy to distinguish objects from local surroundings no matter what else may be in the image. We attempt to capture this distinguishing capability computationally by calculating a measurement that estimates the strength of signal within an object versus the noise in its local neighborhood. First, we hypothesize various sizes for the object and corresponding background … more
Date: July 3, 2007
Creator: Kegelmeyer, L; Fong, P; Glenn, S & Liebman, J
Partner: UNT Libraries Government Documents Department
open access

Target Diagnostic Instrument-Based Controls Framework for the National Ignition Facility (NIF)

Description: The extreme physics of targets shocked by NIF's 192-beam laser are observed by a diverse suite of diagnostics including optical backscatter, time-integrated and gated X-ray sensors, and laser velocity interferometry. Diagnostics to diagnose fusion ignition implosion and neutron emissions are being planned. Many diagnostics will be developed by collaborators at other sites, but ad hoc controls could lead to unreliable and costly operations. An instrument-based controls (I-BC) framework for both … more
Date: October 3, 2007
Creator: Shelton, R. T.; O'Brien, D. W.; Kamperschroer, J. H. & Nelson, J. R.
Partner: UNT Libraries Government Documents Department
open access

ESTIMATING THE STRENGTH OF SINGLE-ENDED DISLOCATION SOURCES IN MICROMETER-SIZED SINGLE CRYSTALS

Description: A recent study indicated that the behavior of single-ended dislocation sources contributes to the flow strength of micrometer-scale crystals. In this study 3D discrete dislocation dynamics simulations of micrometer-sized volumes are used to calculate the effects of anisotropy of dislocation line tension (increasing Poisson's ratio, {nu}) on the strength of single-ended dislocation sources and, to compare them with the strength of double-ended sources of equal length. This is done by directly mo… more
Date: May 3, 2007
Creator: Rao, S I; Dimiduk, D M; Tang, M; Parthasarathy, T A; Uchic, M D & Woodward, C
Partner: UNT Libraries Government Documents Department
open access

Algorithm refinement for fluctuating hydrodynamics

Description: This paper introduces an adaptive mesh and algorithmrefinement method for fluctuating hydrodynamics. This particle-continuumhybrid simulates the dynamics of a compressible fluid with thermalfluctuations. The particle algorithm is direct simulation Monte Carlo(DSMC), a molecular-level scheme based on the Boltzmann equation. Thecontinuum algorithm is based on the Landau-Lifshitz Navier-Stokes (LLNS)equations, which incorporate thermal fluctuations into macroscopichydrodynamics by using stochastic… more
Date: July 3, 2007
Creator: Williams, Sarah A.; Bell, John B. & Garcia, Alejandro L.
Partner: UNT Libraries Government Documents Department
open access

Design of Spintronic Materials with Simple Structures

Description: A brief comparison of conventional electronics and spintronics is given. The key features of half metallic binary compounds with the zincblende structure are presented, using MnAs as an example. We discuss the interactions responsible for the half metallic properties. Special properties of superlattices and a digital ferromagnetic heterostructure incorporating zincblende half metals are also discussed.
Date: May 3, 2007
Creator: Fong, C Y; Qian, M C; Liu, K; Yang, L H & Pask, J E
Partner: UNT Libraries Government Documents Department
open access

CAD Model and Visual Assisted Control System for NIF Target Area Positioners

Description: The National Ignition Facility (NIF) target chamber contains precision motion control systems that reach up to 6 meters into the target chamber for handling targets and diagnostics. Systems include the target positioner, an alignment sensor, and diagnostic manipulators (collectively called positioners). Target chamber shot experiments require a variety of positioner arrangements near the chamber center to be aligned to an accuracy of 10 micrometers. Positioners are some of the largest devices i… more
Date: October 3, 2007
Creator: Tekle, E. A.; Wilson, E. F. & Paik, T. S.
Partner: UNT Libraries Government Documents Department
open access

Correspondence of the Gardner and van Genuchten/Mualem relativepermeability function parameters

Description: The Gardner and van Genuchten models of relativepermeability are widely used in analytical and numerical solutions toflow problems. However, the applicab ility of the Gardner model to realproblems is usually limited, because empirical relative permeability datato calibrate the model are not routinely available. In contrast, vanGenuchten parameters can be estimated using more routinely availablematric potential and saturation data. However, the van Genuchten model isnot amenable to analytical so… more
Date: January 3, 2007
Creator: Ghezzehei, Teamrat A.; Kneafsey, Timothy J. & Su, Grace W.
Partner: UNT Libraries Government Documents Department
open access

SPENT FUEL MANAGEMENT AT THE SAVANNAH RIVER SITE

Description: Spent nuclear fuels are received from reactor sites around the world and are being stored in the L-Basin at the Savannah River Site (SRS) in Aiken, South Carolina. The predominant fuel types are research reactor fuel with aluminum-alloy cladding and aluminum-based fuel. Other fuel materials include stainless steel and Zircaloy cladding with uranium oxide fuel. Chemistry control and corrosion surveillance programs have been established and upgraded since the early 1990's to minimize corrosion de… more
Date: November 3, 2007
Creator: Vormelker, P; Robert Sindelar, R & Richard Deible, R
Partner: UNT Libraries Government Documents Department
open access

Absolute and Relative Surrogate Measurements of the 236U(n,f) Cross Section as a Probe for Angular Momentum Effects

Description: Using both the absolute and relative surrogate techniques, the {sup 236}U(n,f) cross section was deduced over an equivalent neutron energy range of 0 to 20 MeV. A 42 MeV {sup 3}He beam from the 88-Inch Cyclotron at Lawrence Berkeley National Laboratory was used to perform a ({sup 3}He,{alpha}) pickup reaction on targets of {sup 235}U (J{sup {pi}}=7/2{sup -}) and {sup 238}U (J{sup {pi}}=0{sup +}) and the fission decay probabilities were determined. The {sup 235}U({sup 3}He,{alpha}f) and {sup 238… more
Date: April 3, 2007
Creator: Lyles, B; Bernstein, L; Burke, J; Escher, J; Thompson, I; Dietrich, F et al.
Partner: UNT Libraries Government Documents Department
open access

Neutron-Absorbing Coatings for Safe Storage of Fissile Materials with Enhanced Shielding & Criticality Safety

Description: Neutron-absorbing Fe-based amorphous-metal coatings have been developed that are more corrosion resistant than other criticality-control materials, including Al-B{sub 4}C composites, borated stainless steels, and Ni-Cr-Mo-Gd alloys. The presence of relatively high concentration of boron in these coatings not only enhances its neutron-absorption capability, but also enables these coatings to exist in the amorphous state. Exceptional corrosion resistance has been achieved with these Fe-based amor… more
Date: July 3, 2007
Creator: Choi, J.; Farmer, J.; Lee, C.; Fischer, L.; Boussoufi, M.; Liu, B. et al.
Partner: UNT Libraries Government Documents Department
open access

Advances in U.S. Heavy Ion Fusion Science

Description: During the past two years, the US 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 physics for fusion. First experiments combining radial and longitudinal compression {pi} of intense ion beams propagating through background plasma resulted in on-axis beam… more
Date: September 3, 2007
Creator: Barnard, J. J.; Logan, B. G.; Bieniosek, F. M.; Cohen, R. H.; Coleman, J. E.; Davidson, R. C. et al.
Partner: UNT Libraries Government Documents Department
open access

Electrical and Optical Gain Lever Effects in InGaAs Double Quantum Well Diode Lasers

Description: In multisection laser diodes, the amplitude or frequency modulation (AM or FM) efficiency can be improved using the gain lever effect. To study gain lever, InGaAs double quantum well (DQW) edge emitting lasers have been fabricated with integrated passive waveguides and dual sections providing a range of split ratios from 1:1 to 9:1. Both the electrical and the optical gain lever have been examined. An electrical gain lever with greater than 7 dB enhancement of AM efficiency was achieved within … more
Date: January 3, 2007
Creator: Pocha, M D; Goddard, L L; Bond, T C; Nikolic, R J; Vernon, S P; Kallman, J S et al.
Partner: UNT Libraries Government Documents Department
open access

NIF ICCS Test Controller for Automated & Manual Testing

Description: The National Ignition Facility (NIF) Integrated Computer Control System (ICCS) is a large (1.5 MSLOC), hierarchical, distributed system that controls all aspects of the NIF laser [1]. The ICCS team delivers software updates to the NIF facility throughout the year to support shot operations and commissioning activities. In 2006, there were 48 releases of ICCS: 29 full releases, 19 patches. To ensure the quality of each delivery, thousands of manual and automated tests are performed using the ICC… more
Date: October 3, 2007
Creator: Zielinski, J S
Partner: UNT Libraries Government Documents Department
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