SATB1 tethers multiple gene loci to reprogram expression profiledriving breast cancer metastasis (open access)

SATB1 tethers multiple gene loci to reprogram expression profiledriving breast cancer metastasis

Global changes in gene expression occur during tumor progression, as indicated by expression profiling of metastatic tumors. How this occurs is poorly understood. SATB1 functions as a genome organizer by folding chromatin via tethering multiple genomic loci and recruiting chromatin remodeling enzymes to regulate chromatin structure and expression of a large number of genes. Here we show that SATB1 is expressed at high levels in aggressive breast cancer cells, and is undetectable in non-malignant breast epithelial cells. Importantly, RNAi-mediated removal of SATB1 from highly-aggressive MDA-MB-231 cells altered the expression levels of over 1200 genes, restored breast-like acinar polarity in three-dimensional cultures, and prevented the metastastic phenotype in vivo. Conversely, overexpression of SATB1 in the less-aggressive breast cancer cell line Hs578T altered the gene expression profile and increased metastasis dramatically in vivo. Thus, SATB1 is a global regulator of gene expression in breast cancer cells, directly regulating crucial metastasis-associated genes, including ERRB2 (HER2/NEU), TGF-{beta}1, matrix metalloproteinase 3, and metastasin. The identification of SATB1 as a protein that re-programs chromatin organization and transcription profiles to promote breast cancer metastasis suggests a new model for metastasis and may provide means of therapeutic intervention.
Date: July 13, 2006
Creator: Han, Hye-Jung; Kohwi, Yoshinori & Kohwi-Shigematsu, Terumi
Object Type: Article
System: The UNT Digital Library
Toward Fast Computation of Dense Image Correspondence on the GPU (open access)

Toward Fast Computation of Dense Image Correspondence on the GPU

Large-scale video processing systems are needed to support human analysis of massive collections of image streams. Video, from both current small-format and future large-format camera systems, constitutes the single largest data source of the near future, dwarfing the output of all other data sources combined. A critical component to further advances in the processing and analysis of such video streams is the ability to register successive video frames into a common coordinate system at the pixel level. This capability enables further downstream processing, such as background/mover segmentation, 3D model extraction, and compression. We present here our recent work on computing these correspondences. We employ coarse-to-fine hierarchical approach, matching pixels from the domain of a source image to the domain of a target image at successively higher resolutions. Our diamond-style image hierarchy, with total pixel counts increasing by only a factor of two at each level, improves the prediction quality as we advance from level to level, and reduces potential grid artifacts in the results. We demonstrate the quality our approach on real aerial city imagery. We find that registration accuracy is generally on the order of one quarter of a pixel. We also benchmark the fundamental processing kernels on the …
Date: August 13, 2007
Creator: Duchaineau, M; Cohen, J & Vaidya, S
Object Type: Article
System: The UNT Digital Library
Transmission Electron Microscopy Study of InN Nanorods (open access)

Transmission Electron Microscopy Study of InN Nanorods

InN nanorods were grown on a, c-, and r-plane of sapphire and also on Si (111) and GaN (0001) by non-catalytic, template-free hydride metal-organic vapor phase epitaxy and studied by transmission electron microscopy, electron energy loss (EELS) and photoluminescence (PL) at room temperature. These nanocrystals have different shapes and different faceting depending on the substrate used and their crystallographic orientation. EELS measurements have confirmed the high purity of these crystals. The observed PL peak was in the range of 0.9-0.95 eV. The strongest PL intensity was observed for the nanocrystals with the larger diameters.
Date: July 13, 2006
Creator: Liliental-Weber, Z.; Li, X.; Kryliouk, Olga; Park, H.J.; Mangum,J. & Anderson, T.
Object Type: Article
System: The UNT Digital Library
Radiation monitoring with CVD Diamonds and PIN Diodes at BaBar (open access)

Radiation monitoring with CVD Diamonds and PIN Diodes at BaBar

The BaBar experiment at the Stanford Linear Accelerator Center has been using two polycrystalline chemical vapor deposition (pCVD) diamonds and 12 silicon PIN diodes for radiation monitoring and protection of the Silicon Vertex Tracker (SVT). We have used the pCVD diamonds for more than 3 years, and the PIN diodes for 7 years. We will describe the SVT and SVT radiation monitoring system as well as the operational difficulties and radiation damage effects on the PIN diodes and pCVD diamonds in a high-energy physics environment.
Date: February 13, 2008
Creator: Bruinsma, M.; Burchat, P.; Curry, S.; Edwards, A.J.; Kagan, H.; Kass, R. et al.
Object Type: Article
System: The UNT Digital Library
Hyperfine Quenching of the 2s2p 3P0 State of Berylliumlike Ions (open access)

Hyperfine Quenching of the 2s2p 3P0 State of Berylliumlike Ions

The hyperfine-induced 2s2p {sup 3}P{sub 0}-2s{sup 2} {sup 1}S{sub 0} transition rate for Be-like {sup 47}Ti{sup 18+} was recently measured in a storage-ring experiment by Schippers et al. [Phys. Rev. Lett. 98, 033001 (2007)]. The measured value of 0.56(3) s{sup -1} is almost 60% larger than the theoretical value of 0.356 s{sup -1} from a multiconfiguration Dirac-Fock calculation by Marques et al. [Phys. Rev. A 47, 929 (1993)]. In this work, we use a large-scale relativistic configuration-interaction method to calculate these hyperfine-induced rates for ions with Z = 6-92. Coherent hyperfine-quenching effects between the 2s2p {sup 1,3}P{sub 1} states are included in a perturbative as well as a radiation damping approach. Contrary to the claims of Marques et al., contributions from the {sup 1}P{sub 1} state are substantial and lead to a hyperfine-induced rate of 0.67 s{sup -1}, in better agreement with, though larger than, the measured value.
Date: March 13, 2008
Creator: Cheng, K T; Chen, M H & Johnson, W R
Object Type: Article
System: The UNT Digital Library
Spatiotemporal variations in growing season exchanges of CO2, H2O,and sensible heat in agricultural fields of the Southern GreatPlains (open access)

Spatiotemporal variations in growing season exchanges of CO2, H2O,and sensible heat in agricultural fields of the Southern GreatPlains

Climate, vegetation cover, and management create fine-scaleheterogeneity in unirrigated agricultural regions, with important but notwell-quantified consequences for spatial and temporal variations insurface CO2, water, and heat fluxes. We measured eddy covariance fluxesin seven agricultural fields--comprising winter wheat, pasture, andsorghum--in the U.S. Southern Great Plains (SGP) during the 2001-2003growing seasons. Land-cover was the dominant source of variation insurface fluxes, with 50-100 percent differences between fields planted inwinter-spring versus fields planted in summer. Interannual variation wasdriven mainly by precipitation, which varied more than two-fold betweenyears. Peak aboveground biomass and growing-season net ecosystem exchange(NEE) of CO2 increased in rough proportion to precipitation. Based on apartitioning of gross fluxes with a regression model, ecosystemrespiration increased linearly with gross primary production, but with anoffset that increased near the time of seed production. Because theregression model was designed for well-watered periods, it successfullyretrieved NEE and ecosystem parameters during the peak growing season,and identified periods of moisture limitation during the summer. Insummary, the effects of crop type, land management, and water limitationon carbon, water, and energy fluxes were large. Capturing the controllingfactors in landscape scale models will be necessary to estimate theecological feedbacks to climate and other environmental impactsassociated with changing human needs for agricultural production of …
Date: June 13, 2007
Creator: Fischer, Marc L.; Billesbach, David P.; Berry, Joseph A.; Riley,William J. & Torn, Margaret S.
Object Type: Article
System: The UNT Digital Library
MARKOV Model Application to Proliferation Risk Reduction of an Advanced Nuclear System (open access)

MARKOV Model Application to Proliferation Risk Reduction of an Advanced Nuclear System

The Generation IV International Forum (GIF) emphasizes proliferation resistance and physical protection (PR&PP) as a main goal for future nuclear energy systems. The GIF PR&PP Working Group has developed a methodology for the evaluation of these systems. As an application of the methodology, Markov model has been developed for the evaluation of proliferation resistance and is demonstrated for a hypothetical Example Sodium Fast Reactor (ESFR) system. This paper presents the case of diversion by the facility owner/operator to obtain material that could be used in a nuclear weapon. The Markov model is applied to evaluate material diversion strategies. The following features of the Markov model are presented here: (1) An effective detection rate has been introduced to account for the implementation of multiple safeguards approaches at a given strategic point; (2) Technical failure to divert material is modeled as intrinsic barriers related to the design of the facility or the properties of the material in the facility; and (3) Concealment to defeat or degrade the performance of safeguards is recognized in the Markov model. Three proliferation risk measures are calculated directly by the Markov model: the detection probability, technical failure probability, and proliferation time. The material type is indicated by …
Date: July 13, 2008
Creator: Bari, R. A.
Object Type: Article
System: The UNT Digital Library
Incorporation of aqueous reaction kinetics and biodegradation intoTOUGHREACT: Application of a multi-region model to hydrobiogeoChemicaltransport of denitrification and sulfate reduction (open access)

Incorporation of aqueous reaction kinetics and biodegradation intoTOUGHREACT: Application of a multi-region model to hydrobiogeoChemicaltransport of denitrification and sulfate reduction

The need to consider aqueous and sorption kinetics andmicrobiological processes arises in many subsurface problems. Ageneral-rate expression has been implemented into the TOUGHREACTsimulator, which considers multiple mechanisms (pathways) and includesmultiple product, Monod, and inhibition terms. This paper presents aformulation for incorporating kinetic rates among primary species intomass-balance equations. The space discretization used is based on aflexible integral finite difference approach that uses irregular griddingto model bio-geologic structures. A general multi-region model forhydrological transport interacted with microbiological and geochemicalprocesses is proposed. A 1-D reactive transport problem with kineticbiodegradation and sorption was used to test the enhanced simulator,which involves the processes that occur when a pulse of water containingNTA (nitrylotriacetate) and cobalt is injected into a column. The currentsimulation results agree very well with those obtained with othersimulators. The applicability of this general multi-region model wasvalidated by results from a published column experiment ofdenitrification and sulfate reduction. The matches with measured nitrateand sulfate concentrations were adjusted with the interficial areabetween mobile hydrological and immobile biological regions. Resultssuggest that TOUGHREACT can not only be a useful interpretative tool forbiogeochemical experiments, but also can produce insight into processesand parameters of microscopic diffusion and their interplay withbiogeochemical reactions. The geometric- and process-based multi-regionmodel may provide …
Date: July 13, 2006
Creator: Xu, Tianfu
Object Type: Article
System: The UNT Digital Library
CHARACTERIZATION OF A HIGH CURRENT INDUCTION ACCELERATOR ELECTRON BEAM VIA OPTICAL TRANSITION RADIATION FROM DIELECTRIC FOILS (open access)

CHARACTERIZATION OF A HIGH CURRENT INDUCTION ACCELERATOR ELECTRON BEAM VIA OPTICAL TRANSITION RADIATION FROM DIELECTRIC FOILS

Traditionally, thin metal foils are employed for optical transition radiation (OTR) beam diagnostics but the possibility of shorting accelerator insulating surfaces and modifying accelerating fields are concerns. The successful utilization of dielectric foils in place of metal ones could alleviate these issues but necessitates more understanding of the OTR data for inferring desired beam parameters because of the dielectric's finite permittivity. Additionally, the temperature dependence of the relevant foil parameters due to beam heating should be accounted for. Here, we present and discuss sample synthetic diagnostic results of Kapton OTR spot-size measurements from the Flash X-Ray (FXR) accelerator which studies these and sightline effects. These simulations show that in some cases, the observed spot-sizes and radii are noticeably larger than the beam radii.
Date: June 13, 2007
Creator: Tang, V; Brown, C & Houck, T
Object Type: Article
System: The UNT Digital Library
Colloid Science of Metal Nanoparticle Catalysts in 2D and 3D Structures. Challenges of Nucleation, Growth, Composition, Particle Shape, Size Control and their Influence on Activity and Selectivity (open access)

Colloid Science of Metal Nanoparticle Catalysts in 2D and 3D Structures. Challenges of Nucleation, Growth, Composition, Particle Shape, Size Control and their Influence on Activity and Selectivity

Recent breakthroughs in synthesis in nanosciences have achieved control of size and shapes of nanoparticles that are relevant for catalyst design. In this article, we review the advance of synthesis of nanoparticles, fabrication of two and three dimensional model catalyst system, characterization, and studies of activity and selectivity. The ability to synthesize monodispersed platinum and rhodium nanoparticles in the 1-10 nm range permitted us to study the influence of composition, structure, and dynamic properties of monodispersed metal nanoparticle on chemical reactivity and selectivity. We review the importance of size and shape of nanoparticles to determine the reaction selectivity in multi-path reactions. The influence of metal-support interaction has been studied by probing the hot electron flows through the metal-oxide interface in catalytic nanodiodes. Novel designs of nanoparticle catalytic systems are discussed.
Date: February 13, 2008
Creator: Somorjai, Gabor A. & Park, Jeong Y.
Object Type: Article
System: The UNT Digital Library
Charmless Two-Body and Quasi-Two-Body B-decays at BABAR (open access)

Charmless Two-Body and Quasi-Two-Body B-decays at BABAR

The authors present improved measurements of the branching fractions and CP asymmetries in the two-body decays B{sup 0} {yields} {pi}{sup 0}{pi}{sup 0}, B{sup 0} {yields} K{sup 0}{pi}{sup 0} and B{sup 0} {yields} K{sup +}{pi}{sup -} as well as the quasi two-body B{sup 0} {yields} K{sub 1}(1270){sup +} {pi}{sup -} and B{sup 0} {yields} K{sub 1}(1400){sup +} {pi}{sup -} decays. These updated measurements are made using the complete set of BABAR data taken at the Y(4S) resonance, collected between 1999 and 2007 at the PEP-II collider at SLAC.
Date: October 13, 2008
Creator: Ofte, Ingrid
Object Type: Article
System: The UNT Digital Library
Cleanup Verification Package for the 118-B-6, 108-B Solid Waste Burial Ground (open access)

Cleanup Verification Package for the 118-B-6, 108-B Solid Waste Burial Ground

This cleanup verification package documents completion of remedial action for the 118-B-6, 108-B Solid Waste Burial Ground. The 118-B-6 site consisted of 2 concrete pipes buried vertically in the ground and capped by a concrete pad with steel lids. The site was used for the disposal of wastes from the "metal line" of the P-10 Tritium Separation Project.
Date: June 13, 2006
Creator: Proctor, M. L.
Object Type: Report
System: The UNT Digital Library
Shielding Calculations for NSLS-II Beamlines. (open access)

Shielding Calculations for NSLS-II Beamlines.

Brookhaven National Laboratory is in the process of designing a new Electron Synchrotron for scientific research using synchrotron radiation. This facility, called the 'National Synchrotron Light Source II' (NSLS-II), will provide x-ray radiation of ultra-high brightness and exceptional spatial and energy resolution. It will also provide advanced insertion devices, optics, detectors, and robotics, and a suite of scientific instruments designed to maximize the scientific output of the facility. The project scope includes the design, construction, installation, and commissioning of the following accelerators: a 200 MeV linac, a booster accelerator operating from 200 MeV to 3.0 GeV, the storage ring which stores 500 mA current of electrons at an energy of 3.0 GeV and 56 beamlines for experiments. It is planned to operate the facility primarily in a top-off mode, thereby maintaining the maximum variation in stored beam current to < 1%. Because of the very demanding requirements for beam emittance and synchrotron radiation brilliance, the beam life-time is expected to be quite low, on the order of 2 hours. Each of the 56 beamlines will be unique in terms of the source properties and configuration. The shielding designs for five representative beamlines are discussed in this paper.
Date: April 13, 2008
Creator: Job,P.K. & Casey, W.R.
Object Type: Article
System: The UNT Digital Library
Electronic Structure of Halogen Doped CuCr2Se4 (open access)

Electronic Structure of Halogen Doped CuCr2Se4

We have employed element and chemically sensitive X-ray absorption spectroscopy (XAS) and X-ray magnetic circular dichroism (XMCD) in order to address a long standing controversy regarding the electronic and magnetic state of CuCr{sub 2}Se{sub 4} via halogen doping of the Se anion site in CuCr{sub 2}Se{sub 4-x}Y{sub x} (Y=Cl and Br). Long range magnetic order is observed above room temperature for all samples. The Cr L{sub 2,3} XAS spectra show a prevalent 3+ valence for the Cr ions independent of doping concentration and doping agent. The Cu L{sub 2,3} XAS spectra show a combination of 1+ and 2+ valence states for all samples. XMCD spectra indicate the presence of a magnetic moment associated with the Cu ions that is aligned antiparallel to the Cr moment.
Date: September 13, 2008
Creator: Arenholz, Elke; Liberati, M.; Neulinger, J. R.; Chopdekar, R. V.; Bettinger, J. S.; Arenholz, E. et al.
Object Type: Article
System: The UNT Digital Library
Soft X-ray Mirrors for the Linac Coherent Light Source (open access)

Soft X-ray Mirrors for the Linac Coherent Light Source

The Linac Coherent Light Source (LCLS) is a 0.15-1.5 nm wavelength free-electron laser (FEL) being constructed at the Stanford Linear Accelerator Center (SLAC) by a multi-institution consortium, including Lawrence Livermore National Laboratory (LLNL). One of LLNL's responsibilities involves the design and construction of two grazing-incidence mirror systems whose primary intent is to reduce radiation levels in the experimental halls by separating the FEL beam from unwanted high-energy photons. This paper discusses one of these systems, the Soft X-ray Offset Mirror System (SOMS) that will operate in the wavelength range 0.62-1.5 nm (0.827-2.00 keV). The unusual properties of the FEL beam translate to stringent specifications in terms of stability, material choice and mirror properties. It also precludes using approaches previously developed for synchrotron light sources. This situation has led us to a unique mirror design, consisting of a reflective boron carbide layer deposited on a silicon substrate. In the first part of this paper, we discuss the basic system requirements for the SOMS and motivate the need for these novel reflective elements. In the second part of this paper, we discuss the development work we have performed, including simulation and experimental verification of the boron carbide coating properties, and the expected …
Date: August 13, 2007
Creator: Pivovaroff, M. J.; Bionta, R. M.; Mccarville, T. J.; Soufli, R. & Stefan, P. M.
Object Type: Article
System: The UNT Digital Library
Intrinsic and Extrinsic Chemical and Isotopic Tracers for Characterization Of Groundwater Systems (open access)

Intrinsic and Extrinsic Chemical and Isotopic Tracers for Characterization Of Groundwater Systems

In many regions, three dimensional characterization of the groundwater regime is limited by coarse well spacing or borehole lithologic logs of low quality. However, regulatory requirements for drinking water or site remediation may require collection of extensive chemical and water quality data from existing wells. Similarly, for wells installed in the distant past, lithologic logs may not be available, but the wells can be sampled for chemical and isotopic constituents. In these situations, a thorough analysis of trends in chemical and isotopic constituents can be a key component in characterizing the regional groundwater system. On a basin or subbasin scale, especially in areas of intensive groundwater management where artificial recharge is important, introduction of an extrinsic tracer can provide a robust picture of groundwater flow. Dissolved gases are particularly good tracers since a large volume of water can be tagged, there are no real or perceived health risks associated with the tracer, and a very large dynamic range allows detection of a small amount of tagged water in well discharge. Recent applications of the application of extrinsic tracers, used in concert with intrinsic chemical and isotopic tracers, demonstrate the power of chemical analyses in interpreting regional subsurface flow regimes.
Date: September 13, 2007
Creator: Moran, J E; Singleton, M J; Carle, S F & Esser, B K
Object Type: Article
System: The UNT Digital Library
Micropatterning of Gold Substrates Based on Poly(Propylene Sulfide-Bl-Ethylene Glycol), (Pps-Peg) Background Passivation and the Molecular-Assembly Patterning by Lift-Off (Mapl) Technique (open access)

Micropatterning of Gold Substrates Based on Poly(Propylene Sulfide-Bl-Ethylene Glycol), (Pps-Peg) Background Passivation and the Molecular-Assembly Patterning by Lift-Off (Mapl) Technique

Poly(propylene sulfide-bl-ethylene glycol) (PPS-PEG) is an amphiphilic block copolymer that spontaneously adsorbs onto gold from solution. This results in the formation of a stable polymeric layer that renders the surface protein resistant when an appropriate architecture is chosen. The established molecular assembly patterning by lift-off (MAPL) technique can convert a prestructured resist film into a pattern of biointeractive chemistry and a noninteractive background. Employing the MAPL technique, we produced a micron-scale PPS-PEG pattern on a gold substrate, and then characterized the patterned structure with Time-of-Flight Secondary Ion Mass Spectrometry (TOF-SIMS) and Atomic Force Microscopy (AFM). Subsequent exposure of the PPS-PEG/gold pattern to protein adsorption (full human serum) was monitored in situ; SPR-imaging shows a selective adsorption of proteins on gold, but not on PPS-PEG areas. Analysis shows a reduction of serum adsorption up to 93% on the PPS-PEG areas as compared to gold, in good agreement with previous analysis on homogeneously adsorbed PPS-PEG on gold. MAPL patterning of PPS-PEG block copolymers fast, versatile and reproducible, and allows for subsequent use of biosensor-based surface analysis methods.
Date: November 13, 2007
Creator: Feller, L.; Bearinger, J. P.; Wu, L.; Hubbell, J. A.; Textor, M. & Tosatti, S.
Object Type: Article
System: The UNT Digital Library
ANALYSIS RESULTS FOR BUILDING 241 702-AZ A TRAIN (open access)

ANALYSIS RESULTS FOR BUILDING 241 702-AZ A TRAIN

This report presents the analyses results for three samples obtained under RPP-PLAN-28509, Sampling and Analysis Plan for Building 241 702-AZ A Train. The sampling and analysis was done in response to problem evaluation request number PER-2004-6139, 702-AZ Filter Rooms Need Radiological Cleanup Efforts.
Date: December 13, 2006
Creator: JB, DUNCAN; JM, FRYE; CA, COOKE; SW, LI & FJ, BROCKMAN
Object Type: Report
System: The UNT Digital Library
Machine-Detector Interface Issues for the ILCPolarimeters (open access)

Machine-Detector Interface Issues for the ILCPolarimeters

This note examines several Machine-Detector Interface (MDI) issues for the Compton polarimeters in the Beam Delivery System of the International Linear Collider (ILC), including (1) alignment tolerances, (2) impact of crossing angle and IR magnets on spin alignment, (3) Z-pole operation, and (4) costs and conventional facilities.
Date: June 13, 2008
Creator: Woods, Mike
Object Type: Article
System: The UNT Digital Library
Comparison of meteorological measurements from sparse and dense surface observational networks in the U.S. southern Great Plains. (open access)

Comparison of meteorological measurements from sparse and dense surface observational networks in the U.S. southern Great Plains.

The primary objective of this study was to analyze the spatial variability of temperature and relative humidity across Kansas (KS) and Oklahoma (OK) for sparse and dense networks by comparing data from (1) the Surface Meteorological Observing System (SMOS) installations at the Atmospheric Radiation Measurement (ARM; Peppler et al. 2007) Program's Southern Great Plains site and (2) the Oklahoma Mesonet (OKM; McPherson et al. 2007). Given the wealth of observations available from these networks, this study provided the unique opportunity to determine, within a quantifiable statistical limit, an optimal distance between stations deployed for observation of the climatological values of temperature and relative humidity. Average distances between a given station and its closest neighboring station for the ARM SMOS ({approx} 70 km) and the OKM ({approx} 30 km; Brotzge and Richardson 2003) networks provided an excellent framework for comparisons of sparse and dense observations (Figure 1). This study further lays groundwork for a future investigation to determine the necessary spacing between observations for initialization of gridded numerical models. The spatial variability of temperature and relative humidity was examined over KS and OK by comparing observations between station pairs located in three primary domains: (1) a sparse domain in KS, consisting …
Date: August 13, 2008
Creator: Monroe, J. W.; Ritsche, M. T.; Franklin, M.; Kehoe, K. E.; Division, Environmental Science & Oklahoma, Univ.of
Object Type: Report
System: The UNT Digital Library
Cleanup Verification Package for the 300 VTS Waste Site (open access)

Cleanup Verification Package for the 300 VTS Waste Site

This cleanup verification package documents completion of remedial action for the 300 Area Vitrification Test Site, also known as the 300 VTS site. The site was used by Pacific Northwest National Laboratory as a field demonstration site for in situ vitrification of soils containing simulated waste.
Date: March 13, 2006
Creator: Mitchell, S. W. Clark and T. H.
Object Type: Report
System: The UNT Digital Library
University Research Program in Robotics - "Technologies for Micro-Electrical-Mechanical Systems in directed Stockpile Work (DSW) Radiation and Campaigns", Final Technical Annual Report, Project Period 9/1/06 - 8/31/07 (open access)

University Research Program in Robotics - "Technologies for Micro-Electrical-Mechanical Systems in directed Stockpile Work (DSW) Radiation and Campaigns", Final Technical Annual Report, Project Period 9/1/06 - 8/31/07

The University Research Program in Robotics (URPR) is an integrated group of universities performing fundamental research that addresses broad-based robotics and automation needs of the NNSA Directed Stockpile Work (DSW) and Campaigns. The URPR mission is to provide improved capabilities in robotics science and engineering to meet the future needs of all weapon systems and other associated NNSA/DOE activities.
Date: December 13, 2007
Creator: Tulenko, James S. & Crane, Carl D.
Object Type: Report
System: The UNT Digital Library
CeBr3 as a High-Resolution Gamma-Ray Detector (open access)

CeBr3 as a High-Resolution Gamma-Ray Detector

Lanthanum halide (LaBr3:Ce) scintillators have been well-documented as high-resolution gamma-ray detectors that are operated at room temperature. These scintillators have better resolution (<3% at 662 keV) relative to sodium iodide (NaI(Tl)) scintillators (7% at 662 keV), but the naturally occurring radioactive isotope 138La causes self-activity in the crystal that occludes portions of the gamma-ray spectrum. This selfactivity limits the use of LaBr3:Ce in high-sensitivity applications. Cerium, the dopant in the LaBr3:Ce matrix possesses useful scintillation properties, and its selfactivity is on the order of 3750 times less than La; however, Ce has not been fully characterized as the chief component in a scintillation detector. This work investigated Ce as the key scintillation matrix component in a scintillation detector with the hypothesis that CeBr3 promises energy resolution comparable or superior to LaBr3:Ce. The researchers involved with this work believe that CeBr3 may be the answer to obtaining high-temperature, high-resolution spectra with greater sensitivity than LaBr3:Ce.
Date: November 13, 2008
Creator: Michael Reed, Paul Guss, Christopher Contreras
Object Type: Article
System: The UNT Digital Library
SHOCK INITIATION EXPERIMENTS ON PBX 9501 EXPLOSIVE AT PRESSURES BELOW 3 GPa WITH ASSOCIATED IGNITION AND GROWTH MODELING (open access)

SHOCK INITIATION EXPERIMENTS ON PBX 9501 EXPLOSIVE AT PRESSURES BELOW 3 GPa WITH ASSOCIATED IGNITION AND GROWTH MODELING

Shock initiation experiments on the explosive PBX 9501 (95% HMX, 2.5% estane, and 2.5% nitroplasticizer by weight) were performed at pressures below 3 GPa to obtain in-situ pressure gauge data, run-distance-to-detonation thresholds, and Ignition and Growth modeling parameters. Propellant driven gas guns (101 mm and 155 mm) were utilized to initiate the PBX 9501 explosive with manganin piezoresistive pressure gauge packages placed between sample slices. The run-distance-to-detonation points on the Pop-plot for these experiments showed agreement with previously published data and Ignition and Growth modeling parameters were obtained with a good fit to the experimental data. This parameter set will allow accurate code predictions to be calculated for safety scenarios in the low-pressure regime (below 3 GPa) involving PBX 9501 explosive.
Date: June 13, 2007
Creator: Chidester, S K; Thompson, D G; Vandersall, K S; Idar, D J; Tarver, C M; Garcia, F et al.
Object Type: Article
System: The UNT Digital Library