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Environmental Whole-Genome Amplification to Access Microbial Diversity in Contaminated Sediments (open access)

Environmental Whole-Genome Amplification to Access Microbial Diversity in Contaminated Sediments

Low-biomass samples from nitrate and heavy metal contaminated soils yield DNA amounts that have limited use for direct, native analysis and screening. Multiple displacement amplification (MDA) using ?29 DNA polymerase was used to amplify whole genomes from environmental, contaminated, subsurface sediments. By first amplifying the genomic DNA (gDNA), biodiversity analysis and gDNA library construction of microbes found in contaminated soils were made possible. The MDA method was validated by analyzing amplified genome coverage from approximately five Escherichia coli cells, resulting in 99.2 percent genome coverage. The method was further validated by confirming overall representative species coverage and also an amplification bias when amplifying from a mix of eight known bacterial strains. We extracted DNA from samples with extremely low cell densities from a U.S. Department of Energy contaminated site. After amplification, small subunit rRNA analysis revealed relatively even distribution of species across several major phyla. Clone libraries were constructed from the amplified gDNA, and a small subset of clones was used for shotgun sequencing. BLAST analysis of the library clone sequences showed that 64.9 percent of the sequences had significant similarities to known proteins, and ''clusters of orthologous groups'' (COG) analysis revealed that more than half of the sequences from …
Date: December 10, 2005
Creator: Abulencia, C. B.; Wyborski, D. L.; Garcia, J.; Podar, M.; Chen, W.; Chang, S. H. et al.
System: The UNT Digital Library
Transverse-momentum dependent modification of dynamic texture in central Au+Au collisions at sqrt(sNN) = 200 GeV (open access)

Transverse-momentum dependent modification of dynamic texture in central Au+Au collisions at sqrt(sNN) = 200 GeV

Correlations in the hadron distributions produced in relativistic Au+Au collisions are studied in the discrete wavelet expansion method. The analysis is performed in the space of pseudorapidity (|{eta}| {le} 1) and azimuth (full 2{pi}) in bins of transverse momentum (p{sub t}) from 0.14 {le} p{sub t} {le} 2.1 GeV/c. In peripheral Au+Au collisions a correlation structure ascribed to minijet fragmentation is observed. It evolves with collision centrality and p{sub t} in a way not seen before which suggests strong dissipation of minijet fragmentation in the longitudinally-expanding medium.
Date: January 10, 2005
Creator: Adams, J.; Aggarwal, M. M.; Ahammed, Z.; Amonett, J.; Anderson, B. D.; Arkhipkin, D. et al.
System: The UNT Digital Library
General computational spectroscopic framework applied to Z-pinch dynamic hohlraum K-shell argon spectra (open access)

General computational spectroscopic framework applied to Z-pinch dynamic hohlraum K-shell argon spectra

We describe a general computational spectroscopic framework for interpreting observed spectra. The framework compares synthetic spectra with measured spectra, then optimizes the agreement using the Dakota toolkit to minimize a merit function that incorporates established spectroscopic techniques. We generate synthetic spectra using the self-consistent nonlocal thermodynamic equilibrium atomic kinetics and radiative transfer code Cretin, relativistic atomic structure and cross section data from Hullac, and detailed spectral line shapes from Totalb. We test the capabilities of both our synthetic spectra model and general spectroscopic framework by analyzing a K-shell argon spectrum from a Z-pinch dynamic hohlraum inertial confinement fusion capsule implosion experiment. The framework obtains close agreement between an experimental spectrum measured by a time integrated focusing spectrometer and the optimal synthetic spectrum. The synthetic spectra show that considering the spatial extent of the capsule and including the effects of optically thick resonance lines significantly affects the interpretation of measured spectra.
Date: January 10, 2005
Creator: Adams, M L; Sinars, D B & Scott, H A
System: The UNT Digital Library
The Dynamic Range of Ultra-High Resolution Cryogenic Gamma-ray Spectrometers (open access)

The Dynamic Range of Ultra-High Resolution Cryogenic Gamma-ray Spectrometers

We are developing high-resolution cryogenic gamma-ray spectrometers for nuclear science and non-proliferation applications. The gamma-ray detectors are composed of a bulk superconducting Sn foil absorber attached to multilayer Mo/Cu transition-edge sensors (TES). The energy resolution achieved with a 1 x 1 x 0.25 mm{sup 3} Sn absorber is 50 -90eV for {gamma}-rays up to 100 keV and it decreases for large absorber sizes. We discuss the trade-offs between energy resolution and dynamic range, as well as development of TES arrays for higher count rates and better sensitivity.
Date: August 10, 2005
Creator: Ali, S.; Terracol, S. F.; Drury, O. B. & Friedrich, S.
System: The UNT Digital Library
Correlation Function and Generalized Master Equation of Arbitrary Age (open access)

Correlation Function and Generalized Master Equation of Arbitrary Age

Article discussing research on correlation function and generalized master equation of arbitrary age.
Date: June 10, 2005
Creator: Allegrini, Paolo; Aquino, Gerardo; Grigolini, Paolo; Palatella, Luigi; Rosa, Angelo & West, Bruce J.
System: The UNT Digital Library
Measurement of the Branching Fraction and Decay Rate Asymmetry of B to D_pi+ pi- pi0 K- (open access)

Measurement of the Branching Fraction and Decay Rate Asymmetry of B to D_pi+ pi- pi0 K-

The authors report the observation of the decay B{sup -} {yields} D{sub {pi}{sup +}{pi}{sup -}{pi}{sup 0}}K{sup -}, where D{sub {pi}{sup +}{pi}{sup -}{pi}{sup 0}} indicates a neutral D meson detected in the final state {pi}{sup +}{pi}{sup -}{pi}{sup 0}, excluding K{sub S}{sup 0}{pi}{sup 0}. This doubly Cabibbo-suppressed decay chain can be used to measure the CKM phase {gamma}. Using about 229 million e{sup +}e{sup -} {yields} B{bar B} events recorded by the BABAR experiment at the PEP-II e{sup +}e{sup -} storage ring, they measure the branching fraction {Beta}(B{sup -} {yields} D{sub {pi}{sup +}{pi}{sup -}{pi}{sup 0}K{sup -}}) = (5.5 {+-} 1.0 (stat.) {+-} 0.7 (syst.)) x 10{sup -6} and the decay rate asymmetry A = -0.02 {+-} 0.16 (stat.) {+-} 0.03 (syst.) for the full decay chain.
Date: June 10, 2005
Creator: Aubert, B.; Barate, R.; Boutigny, D.; Couderc, F.; Karyotakis, Y.; Lees, J. P. et al.
System: The UNT Digital Library
Ion Beam Modification of Materials (open access)

Ion Beam Modification of Materials

This volume contains the proceedings of the 14th International Conference on Ion Beam Modification of Materials, IBMM 2004, and is published by Elsevier-Science Publishers as a special issue of Nuclear Instruments and Methods B. The conference series is the major international forum to present and discuss recent research results and future directions in the field of ion beam modification, synthesis and characterization of materials. The first conference in the series was held in Budapest, Hungary, 1978, and subsequent conferences were held every two years at locations around the Globe, most recently in Japan, Brazil, and the Netherlands. The series brings together physicists, materials scientists, and ion beam specialists from all over the world. The official conference language is English. IBMM 2004 was held on September 5-10, 2004. The focus was on materials science involving both basic ion-solid interaction processes and property changes occurring either during or subsequent to ion bombardment and ion beam processing in relation to materials and device applications. Areas of research included Nanostructures, Multiscale Modeling, Patterning of Surfaces, Focused Ion Beams, Defects in Semiconductors, Insulators and Metals, Cluster Beams, Radiation Effects in Materials, Photonic Devices, Ion Implantation, Ion Beams in Biology and Medicine including New Materials, Imaging, …
Date: October 10, 2005
Creator: Averback, B; de la Rubia, T D; Felter, T E; Hamza, A V & Rehn, L E
System: The UNT Digital Library
Diagnostic Systems Plan for the Advanced Light Source Top-OffUpgrade (open access)

Diagnostic Systems Plan for the Advanced Light Source Top-OffUpgrade

The Advanced Light Source (ALS) will soon be upgraded to enable top-off operations [1], in which electrons are quasi-continuously injected to produce constant stored beam current. The upgrade is structured in two phases. First, we will upgrade our injector from 1.5 GeV to 1.9 GeV to allow full energy injection and will start top-off operations. In the second phase, we will upgrade the Booster Ring (BR) with a bunch cleaning system to allow high bunch purity top-off injection. A diagnostics upgrade will be crucial for success in both phases of the top-off project, and our plan for it is described in this paper. New booster ring diagnostics will include updated beam position monitor (BPM) electronics, a tune monitoring system, and a new scraper. Two new synchrotron light monitors and a beam stop will be added to the booster-to-storage ring transfer line (BTS), and all the existing beam current monitors along the accelerator chain will be integrated into a single injection efficiency monitoring application. A dedicated bunch purity monitor will be installed in the storage ring (SR). Together, these diagnostic upgrades will enable smooth commissioning of the full energy injector and a quick transition to high quality top-off operation at the …
Date: May 10, 2005
Creator: Barry, Walter; Chin, Mike; Robin, David; Sannibale, Fernando; Scarvie, Tom & Steier, Christoph
System: The UNT Digital Library
Neutron Detection with Cryogenics and Semiconductors (open access)

Neutron Detection with Cryogenics and Semiconductors

The common methods of neutron detection are reviewed with special attention paid to the application of cryogenics and semiconductors to the problem. The authors' work with LiF- and boron-based cryogenic instruments is described as well as the use of CdTe and HgI{sub 2} for direct detection of neutrons.
Date: March 10, 2005
Creator: Bell, Z. W.; Carpenter, D. A.; Cristy, S. S. & Lamberti, V. E.
System: The UNT Digital Library
REVIEW OF VARIOUS APPROACHES TO ADDRESS HIGH CURRENTS IN SRF ELECTRON LINACS. (open access)

REVIEW OF VARIOUS APPROACHES TO ADDRESS HIGH CURRENTS IN SRF ELECTRON LINACS.

The combination of high-brightness electron sources and high-current SRF Energy Recovery Linacs (ERL) leads to a new emerging technology: High-power, high-brightness electron beams. This technology enables extremely high average power Free-Electron Lasers, a new generation of extreme brightness light sources, electron coolers of high-energy hadron storage rings, polarized electron-hadron colliders of very high luminosity, compact Thomson scattering X-ray sources, terahertz radiation generators and much more. What is typical for many of these applications is the need for very high current, defined here as over 100 mA average current, and high brightness, which is charge dependant, but needs to be in the range of between sub micron up to perhaps 50 microns, usually the lower--the better. Suffice it to say that while there are a number of projects aiming at this level of performance, none is anywhere near it. This work will review the problems associated with the achievement of such performance and the various approaches taken in a number of laboratories around the world to address the issues.
Date: July 10, 2005
Creator: Ben-Zvi, Ilan
System: The UNT Digital Library
Microscopic failure behavior of nanoporous Gold (open access)

Microscopic failure behavior of nanoporous Gold

Nanoporous metals have recently attracted considerable interest fueled by potential sensor and actuator applications. One of the key issues in this context is the synthesis of high yield strength materials. Nanoporous Au (np-Au) has been suggested as a candidate due to its monolithic character. The material can be synthesized by dealloying Ag-Au alloys, and exhibits an open sponge-like morphology of interconnecting Au ligaments with a typical pore size distribution on the nanometer length scale. Unfortunately, very little is known about the mechanical properties of np-Au besides a length-scale dependent ductile-brittle transition. A key question in this context is: what causes the macroscopic brittleness of np-Au? Is the normal dislocation-mediated plastic deformation suppressed in nanoscale Au ligaments, or is the brittleness a consequence of the macroscopic morphology? Here, we report on the fracture behavior of nanoporous Au studied by scanning electron microscopy. Specifically, we demonstrate the microscopic ductility of nanometer-sized Au ligaments. The observed fracture behavior seems to be general for nanoporous metals, and can be understood in terms of simple fuse networks.
Date: January 10, 2005
Creator: Biener, J.; Hodge, A. & Hamza, A.
System: The UNT Digital Library
Risks of Mortality and Morbidity from Worldwide Terrorism: 1968-2004 (open access)

Risks of Mortality and Morbidity from Worldwide Terrorism: 1968-2004

Worldwide data on terrorist incidents between 1968 and 2004 gathered by the RAND corporation and the Oklahoma City National Memorial Institute for the Prevention of Terrorism (MIPT) were assessed for patterns and trends in morbidity/mortality. Adjusted data analyzed involve a total of 19,828 events, 7,401 ''adverse'' events (each causing {ge}1 victim), and 86,568 ''casualties'' (injuries) of which 25,408 were fatal. Most terror-related adverse events, casualties and deaths involved bombs and guns. Weapon-specific patterns and terror-related risk levels in Israel (IS) have differed markedly from those of all other regions combined (OR). IS had a fatal fraction of casualties about half that of OR, but has experienced relatively constant lifetime terror-related casualty risks on the order of 0.5%--a level 2 to 3 orders of magnitude more than those experienced in OR that increased {approx}100-fold over the same period. Individual event fatality has increased steadily, the median increasing from 14 to 50%. Lorenz curves obtained indicate substantial dispersion among victim/event rates: about half of all victims were caused by the top 2.5% (or 10%) of harm-ranked events in OR (or IS). Extreme values of victim/event rates were approximated fairly well by generalized Pareto models (typically used to fit to data on forest …
Date: February 10, 2005
Creator: Bogen, K. T. & Jones, E. D.
System: The UNT Digital Library
Improved Wind and Turbulence Measurements Using a Low-Cost 3-D Sonic Anemometer at a Low-Wind Site (open access)

Improved Wind and Turbulence Measurements Using a Low-Cost 3-D Sonic Anemometer at a Low-Wind Site

None
Date: May 10, 2005
Creator: Bowen, B M
System: The UNT Digital Library
Imaging Performance of the Si/Ge Hybrid Compton Imager (open access)

Imaging Performance of the Si/Ge Hybrid Compton Imager

The point spread function (PSF) of a fully-instrumented silicon/germanium Compton telescope has been measured as a function of energy and angle. Overall, the resolution ranged from 3{sup o} to 4{sup o} FWHM over most of the energy range and field of view. The various contributions to the resolution have been quantified. These contributions include the energy uncertainty and position uncertainty of the detector; source energy; Doppler broadening; and the 1/r broadening characteristic of Compton back-projection. Furthermore, a distortion of the PSF is observed for sources imaged off-axis from the detector. These contributions are discussed and compared to theory and simulations.
Date: November 10, 2005
Creator: Burks, M; Chivers, D; Cork, C; Cunningham, M; Fabris, L; Gunter, D et al.
System: The UNT Digital Library
Kinetics of HMX and CP Decomposition and Their Extrapolation for Lifetime Assessment (open access)

Kinetics of HMX and CP Decomposition and Their Extrapolation for Lifetime Assessment

Decomposition kinetics are determined for HMX (nitramine octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine) and CP (2-(5-cyanotetrazalato) pentaammine cobalt (III) perchlorate) separately and together. For high levels of thermal stress, the two materials decompose faster as a mixture than individually. This effect is observed both in high-temperature thermal analysis experiments and in long-term thermal aging experiments. An Arrhenius plot of the 10% level of HMX decomposition by itself from a diverse set of experiments is linear from 120 to 260 C, with an apparent activation energy of 165 kJ/mol. Similar but less extensive thermal analysis data for the mixture suggests a slightly lower activation energy for the mixture, and an analogous extrapolation is consistent with the amount of gas observed in the long-term detonator aging experiments, which is about 30 times greater than expected from HMX by itself for 50 months at 100 C. Even with this acceleration, however, it would take {approx}10,000 years to achieve 10% decomposition at {approx}30 C. Correspondingly, negligible decomposition is predicted by this kinetic model for a few decades aging at temperatures slightly above ambient. This prediction is consistent with additional sealed-tube aging experiments at 100-120 C, which are estimated to have an effective thermal dose greater than that from decades …
Date: March 10, 2005
Creator: Burnham, A K; Weese, R K & Andrzejewski, W J
System: The UNT Digital Library
Effect of Activation Cross Section Uncertainties on the Radiological Assessment of the MFE/DEMO First Wall (open access)

Effect of Activation Cross Section Uncertainties on the Radiological Assessment of the MFE/DEMO First Wall

A Monte Carlo procedure has been applied in this work in order to address the impact of activation cross sections (XS) uncertainties on contact dose rate and decay heat calculations for the outboard first wall (FW) of a magnetic fusion energy (MFE) demonstration (DEMO) reactor. The XSs inducing the major uncertainty in the prediction of activation related quantities have been identified. Results have shown that for times corresponding to maintenance activities the uncertainties effect is insignificant since the dominant XSs involved in these calculations are based on accurate experimental data evaluations. However, for times corresponding to waste management/recycling activities, the errors induced by the XSs uncertainties, which in this case are evaluated using systematic models, must be considered. It has been found that two particular isotopes, {sup 60}Co and {sup 94}Nb, are key contributors to the global DEMO FW activation uncertainty results. In these cases, the benefit from further improvements in the accuracy of the critical reaction XSs is discussed.
Date: May 10, 2005
Creator: Cabellos, O; Reyes, S; Sanz, J; Rodriguez, A; Youssef, M & Sawan, M
System: The UNT Digital Library
Euler angles for G2 (open access)

Euler angles for G2

We provide a simple parameterization for the group G2, which is analogous to the Euler parameterization for SU(2). We show how to obtain the general element of the group in a form emphasizing the structure of the fibration of G2 with fiber SO(4) and base H, the variety of quaternionic subalgebras of octonions. In particular this allows us to obtain a simple expression for the Haar measure on G2. Moreover, as a by-product it yields a concrete realization and an Einstein metric for H.
Date: March 10, 2005
Creator: Cacciatori, Sergio; Cerchiai, Bianca Letizia; della Vedova,Alberto; Ortenzi, Giovanni & Scotti, Antonio
System: The UNT Digital Library
Overlapping Schwarz for Nonlinear Problems. An Element Agglomeration Nonlinear Additive Schwarz Preconditioned Newton Method for Unstructured Finite Element Problems (open access)

Overlapping Schwarz for Nonlinear Problems. An Element Agglomeration Nonlinear Additive Schwarz Preconditioned Newton Method for Unstructured Finite Element Problems

This paper extends previous results on nonlinear Schwarz preconditioning ([4]) to unstructured finite element elliptic problems exploiting now nonlocal (but small) subspaces. The non-local finite element subspaces are associated with subdomains obtained from a non-overlapping element partitioning of the original set of elements and are coarse outside the prescribed element subdomain. The coarsening is based on a modification of the agglomeration based AMGe method proposed in [8]. Then, the algebraic construction from [9] of the corresponding non-linear finite element subproblems is applied to generate the subspace based nonlinear preconditioner. The overall nonlinearly preconditioned problem is solved by an inexact Newton method. Numerical illustration is also provided.
Date: February 10, 2005
Creator: Cai, X C; Marcinkowski, L & Vassilevski, P S
System: The UNT Digital Library
Dispersion Analysis of the Pulseline Accelerator (open access)

Dispersion Analysis of the Pulseline Accelerator

The authors analyze the sheath helix model of the pulseline accelerator. They find the dispersion relation for a shielded helix with a dielectric material between the shield and the helix and compare it against the results from 3-D electromagnetic simulations. Expressions for the fields near the beam axis are obtained. A scheme to taper the properties of the helix to maintain synchronism with the accelerated ions is described. An approximate circuit model of the system that includes beam loading is derived.
Date: May 10, 2005
Creator: Caporaso, G J; Briggs, R J; Poole, B R & Nelson, S D
System: The UNT Digital Library
Fracture Permeability Evolution in Desert Peak Quartz Monzonite (open access)

Fracture Permeability Evolution in Desert Peak Quartz Monzonite

Fracture flow experiments are being conducted on quartz monzonite core from the Desert Peak East EGS site, Churchill County, Nevada. The flow experiments are conducted at temperatures of 167-169 C and 5.5 MPa confining pressure through artificial fractures. Two injection fluids, a saline solution and a silica-bearing solution, have been used to date. Flow rates are typically 0.02 mL/min, but other rates have been used. The fracture surfaces are characterized with a contact profilometer. The profilometry data demonstrate that it is possible to fabricate statistically similar fracture surfaces and enable us to map aperture variations, which we use in numerical simulations. Effluent samples are collected for chemical analysis. The fluid pressure gradient is measured across the specimen and effective hydraulic apertures are calculated. The experiments show a reduction in permeability over time for both injection fluids, but a more rapid loss of permeability was observed for the silica-bearing solution. The calculated hydraulic aperture is observed to decrease by 17% for the saline solution and 75% for the silica-bearing fluid, respectively. Electrical resistivity measurements, which are sensitive to the ionic content of the pore fluid, provide additional evidence of fluid-rock interactions.
Date: May 10, 2005
Creator: Carlson, S. R.; Roberts, J. J.; Detwiler, R. L.; Viani, B. E. & Roberts, S. K.
System: The UNT Digital Library
Chiral Suppression of Scalar Glueball Decay (open access)

Chiral Suppression of Scalar Glueball Decay

Because glueballs are SU(3){sub Flavor} singlets, they are expected to couple equally to u,d, and s quarks, so that equal coupling strengths to {pi}{sup +}{pi}{sup -} and K{sup +}K{sup -} are predicted. However, we show that chiral symmetry implies the scalar glueball amplitude for G{sub 0} {yields} {bar q}q is proportional to the quark mass, so that mixing with {bar s}s mesons is enhanced and decays to K{sup +}K{sup -} are favored over {pi}{sup +}{pi}{sup -}. Together with evidence from lattice calculations and from experiment, this supports the hypothesis that f{sub 0}(1710) is the ground state scalar glueball.
Date: June 10, 2005
Creator: Chanowitz, Michael S.
System: The UNT Digital Library
Transverse Beam Instability in a Compact Dielectric Wall Induction Accelerator (open access)

Transverse Beam Instability in a Compact Dielectric Wall Induction Accelerator

Using the dielectric wall accelerator technology, they are developing a compact induction accelerator system primarily intended for pulsed radiography. Unlike the typical induction accelerator cell that is long compared with its accelerating gap width, the proposed dielectric wall induction accelerator cell is short and its accelerating gap width is comparable with the cell length. In this geometry, the RF modes may be coupled from one cell to the next. They will present recent results of RF modeling of the cells and a prediction of the transverse beam instability on a 2-kA, 8-MeV beam.
Date: May 10, 2005
Creator: Chen, Y.; McCarrick, J. F. & Nelson, S. D.
System: The UNT Digital Library
On the Possibility of the Sheath-Driven, Finite-Beta Modes Localized Near the Divertor Plate (open access)

On the Possibility of the Sheath-Driven, Finite-Beta Modes Localized Near the Divertor Plate

It is shown that, in a finite beta plasma, there may exist sheath driven modes whose amplitude decreases exponentially with the distance from the divertor plate. The modes are sensitive to the radial tilt of the divertor plate. The short-wavelength branch of the instability, with the cross-field wavelength Dof order of a few ion gyroradii, is present in the case of a ''positive'' tilt of the divertor plate, whereas the long-wavelength branch, with D of order of 10 or so gyroradii is unstable for the opposite sign of the tilt. The parallel e-folding length becomes less than the distance from the plate to the X point (thereby making the mode insensitive to the processes near the X-point and the upper scrape-off layer) at the plasma betas exceeding (2-3) {center_dot} 10{sup -4}. A detailed analysis of the dispersion relations is provided. The features of the modes that can be used for their experimental identification are discussed. It is pointed out that the analog of these modes may also exist in linear plasma devices with shaped end electrodes.
Date: February 10, 2005
Creator: Cohen, R & Ryutov, D
System: The UNT Digital Library
Dynamics of an Isolated Blob in the Presence of the X-Point (open access)

Dynamics of an Isolated Blob in the Presence of the X-Point

The interplay of X-point shearing and axial plasma redistribution along a moving flux tube is discussed. Blobs limited to the main scrape-off-layer and the blobs entirely confined in the divertor region are identified. A strong effect of the radial tilt of the divertor plate on ''divertor'' blobs is found.
Date: October 10, 2005
Creator: Cohen, R. H. & Ryutov, D. D.
System: The UNT Digital Library