Investigating the Affinities and Persistence of VX Nerve Agent in Environmental Matrices (open access)

Investigating the Affinities and Persistence of VX Nerve Agent in Environmental Matrices

Laboratory experiments were conducted to determine environmental variables that affect the affinities and persistence of the nerve agent O-ethyl S-(2-diisopropylaminoethyl) methylphosphonothiolate (VX) at dilute concentrations in environmental matrices. Quantitative analyses of VX and its degradation products were performed using LC-MS. Batch hydrolysis experiments demonstrated an increasing hydrolysis rate as pH increased, as shown in previous studies, but also indicated that dissolved aqueous constituents can cause significant differences in the absolute hydrolysis rate. Adsorption isotherms from batch aqueous experiments revealed that VX has a high affinity for hydrophobic organics, a moderate affinity for montmorillonite clay, and a very low affinity for an iron-oxyhydroxide soil mineral, goethite. The adsorption on goethite was increased with the presence of dissolved organic matter in solution. VX degraded rapidly when dried onto goethite, when an inner-sphere complex was forced. No enhanced degradation occurred with goethite in small amounts water. These results suggest that aqueous conditions have important controls on VX adsorption and degradation in the environment and a more mechanistic understanding of these controls is needed in order to enable accurate predictions of its long-term fate and persistence.
Date: March 9, 2004
Creator: Love, A H; Vance, A L; Reynolds, J G & Davisson, M L
Object Type: Article
System: The UNT Digital Library
Normalized Texture Motifs and Their Application to Statistical Object Modeling (open access)

Normalized Texture Motifs and Their Application to Statistical Object Modeling

A fundamental challenge in applying texture features to statistical object modeling is recognizing differently oriented spatial patterns. Rows of moored boats in remote sensed images of harbors should be consistently labeled regardless of the orientation of the harbors, or of the boats within the harbors. This is not straightforward to do, however, when using anisotropic texture features to characterize the spatial patterns. We here propose an elegant solution, termed normalized texture motifs, that uses a parametric statistical model to characterize the patterns regardless of their orientation. The models are learned in an unsupervised fashion from arbitrarily orientated training samples. The proposed approach is general enough to be used with a large category of orientation-selective texture features.
Date: March 9, 2004
Creator: Newsam, S D
Object Type: Article
System: The UNT Digital Library
A technique for accelerating the convergence of restarted GMRES (open access)

A technique for accelerating the convergence of restarted GMRES

We have observed that the residual vectors at the end of each restart cycle of restarted GMRES often alternate direction in a cyclic fashion, thereby slowing convergence. We present a new technique for accelerating the convergence of restarted GMRES by disrupting this alternating pattern. The new algorithm resembles a full conjugate gradient method with polynomial preconditioning, and its implementation requires minimal changes to the standard restarted GMRES algorithm.
Date: March 9, 2004
Creator: Baker, A H; Jessup, E R & Manteuffel, T
Object Type: Article
System: The UNT Digital Library
2004 status report: Savings estimates for the Energy Star(R)voluntarylabeling program (open access)

2004 status report: Savings estimates for the Energy Star(R)voluntarylabeling program

ENERGY STAR(R) is a voluntary labeling program designed toidentify and promote energy-efficient products, buildings and practices.Operated jointly by the Environmental Protection Agency (EPA) and theU.S. Department of Energy (DOE), ENERGY STAR labels exist for more thanthirty products, spanning office equipment, residential heating andcooling equipment, commercial and residential lighting, home electronics,and major appliances. This report presents savings estimates for a subsetof ENERGY STAR labeled products. We present estimates of the energy,dollar and carbon savings achieved by the program in the year 2003, whatwe expect in 2004, and provide savings forecasts for two marketpenetration scenarios for the periods 2004 to 2010 and 2004 to 2020. Thetarget market penetration forecast represents our best estimate of futureENERGY STAR savings. It is based on realistic market penetration goalsfor each of the products. We also provide a forecast under the assumptionof 100 percent market penetration; that is, we assume that all purchasersbuy ENERGY STAR-compliant products instead of standard efficiencyproducts throughout the analysis period.
Date: March 9, 2004
Creator: Webber, Carrie A.; Brown, Richard E. & McWhinney, Marla
Object Type: Report
System: The UNT Digital Library
Luminosity and Redshift dependence of quasar spectral properties (open access)

Luminosity and Redshift dependence of quasar spectral properties

Using a large sample of quasar spectra from the SDSS, we examine the composite spectral trends of quasars as functions of both redshift and luminosity, independently of one another. Aside from the well known Baldwin effect (BE)--the decrease of line equivalent width with luminosity--the average spectral properties are remarkably similar. Host galaxy contamination and the BE are the primary causes for apparent changes in the average spectral slope of the quasars. The BE is detected for most emission lines, including the Balmer lines, but with several exceptions including NV1240A. Emission line shifts of several lines are associated with the BE. The BE is mainly a function of luminosity, but also partly a function of redshift in that line equivalent widths become stronger with redshift. Some of the complex iron features change with redshift, particularly near the small blue bump region.
Date: March 9, 2004
Creator: al., Daniel E. Vanden Berk et
Object Type: Article
System: The UNT Digital Library
Summary of the 2003 Moriond Workshop on electroweak interactions and unified theories (open access)

Summary of the 2003 Moriond Workshop on electroweak interactions and unified theories

The 2003 Moriond Workshop on Electroweak Interactions and Unified Theories covered a very rich, diverse array of recent results concerning neutrinos, astrophysics and cosmology, searches for new particles, Higgs physics, precision low-energy measurements, quark flavor physics, CP violation, and electroweak interactions. In this summary, we recapitulate some of the highlights. We update many of the results reported at the Workshop to include newer findings reported during Summer, 2003. In this report, We recount some of the highlights of the 2003 Moriond Workshop on Electroweak Interactions and Unified Theories.
Date: March 9, 2004
Creator: Kayser, Boris
Object Type: Article
System: The UNT Digital Library
Recent results in high pT physics from CDF (open access)

Recent results in high pT physics from CDF

The authors present the most recent high p{sub T} results from the CDF experiment using p{bar p} collisions at {radical}s = 1.96 TeV produced at the Tevatron Collider at Fermilab. They summarize results in electroweak physics, top physics and searches for physics beyond the Standard Model. Many measurements of important signals like W boson, Z boson, and the top quark have been reestablished. Taking advantage of the increase in energy and detector upgrades, these measurements already begin to be competitive with previous results.
Date: March 9, 2004
Creator: Veramendi, G.
Object Type: Article
System: The UNT Digital Library
A Cryogenic test stand for LHC quadrupole magnets (open access)

A Cryogenic test stand for LHC quadrupole magnets

A new test stand for testing LHC interaction region (IR) quadrupole magnets at the Fermilab Magnet Test Facility has been designed and operated. The test stand uses a double bath system with a lambda plate to provide the magnet with a stagnant bath of pressurized He II at 1.9 K and 0.13 MPa. A cryostated magnet 0.91 m in diameter and up to 13 m in length can be accommodated. This paper describes the system design and operation. Issues related to both 4.5 K and 1.9 K operations and magnet quenching are highlighted. An overview of the data acquisition and cryogenics controls systems is also included.
Date: March 9, 2004
Creator: al., R. J. Rabehl et
Object Type: Article
System: The UNT Digital Library
An Updated Regional Water Table of the Savannah River Site and Related Coverages (open access)

An Updated Regional Water Table of the Savannah River Site and Related Coverages

A new regional-scale map of the water table configuration beneath the Savannah River Site and its surrounding area has been developed. This map is an update to the regional watertable map presented in1998. While similar methods were used to develop the updated coverages, increased accuracy was achieved due to several factors, including: (a) more data (new wells and additional measurements), (b) use of median versus mean water levels for water table contour development, (c) culling erroneous values from the data records, and (d) eliminating wells discovered to not reflect natural conditions.
Date: March 9, 2004
Creator: Hiergesell, R.A.
Object Type: Report
System: The UNT Digital Library
Effect of emittance and rms phase error on angular flux density and pinhole flux-a simulation study of two undulators at 10.5 mm gap including very high harmonics. (open access)

Effect of emittance and rms phase error on angular flux density and pinhole flux-a simulation study of two undulators at 10.5 mm gap including very high harmonics.

There is a trade-off between how much effort should go into the tuning of insertion devices to reduce their rms phase errors and the actual benefits achieved in spectral quality when the real APS beam emittance and beam energy spread are taken into account. In the magnetic measurement laboratory, the measured magnetic fields are analyzed in terms of the rms phase error and the angular flux density, which is calculated from the measured fields for an ideal electron beam, i.e., a zero-emittance beam. In this study, we go beyond the case of an ideal beam to study the effect of the APS beam emittance and beam energy spread on the angular flux density and the pinhole flux (for a typical pinhole size that covers most of the central cone of the radiation) for real-field insertion devices to get an estimate of how low an rms phase error is reasonable to attain. The results presented here are directly applicable to the APS ''canted'' undulators of type A (planar permanent-magnet hybrid insertion devices 2.1 m long and 3.3 cm period length) but also to the standard undulators A (which have a similar design with the same period length but are 0.3 m …
Date: March 9, 2004
Creator: Dejus, R.
Object Type: Report
System: The UNT Digital Library
Anisotropic flow in the forward directions at {radical}s{sub NN} = 200 GeV (open access)

Anisotropic flow in the forward directions at {radical}s{sub NN} = 200 GeV

The addition of the two Forward TPCs to the STAR detector allows one to measure anisotropic flow at forward pseudorapidities. This made possible the first measurement of directed flow at collision energies of {radical}s{sub NN} = 200 GeV. PHOBOS' results on elliptic flow at forward rapidities were confirmed, and the sign of v{sub 2} was determined to be positive for the first time at RHIC energies. The higher harmonic, v{sub 4}, is consistent with the recently suggested v{sub 2}2 scaling behavior.
Date: March 9, 2004
Creator: Oldenburg, Markus D.
Object Type: Article
System: The UNT Digital Library
Bioorganometallic chemistry: biocatalytic oxidation reactions with biomimetic nad+/nadh co-factors and [cp*rh(bpy)h]+ for selective organic synthesis (open access)

Bioorganometallic chemistry: biocatalytic oxidation reactions with biomimetic nad+/nadh co-factors and [cp*rh(bpy)h]+ for selective organic synthesis

The biocatalytic, regioselective hydroxylation of 2-hydroxybiphenyl to the corresponding catechol was accomplished utilizing the monooxygenase 2-hydroxybiphenyl 3-monooxygenase (HbpA). The necessary natural nicotinamide adenine dinucleotide (NAD{sup +}) co-factor for this biocatalytic process was replaced by a biomimetic co-factor, N-benzylnicotinamide bromide, 1a. The interaction between the flavin (FAD) containing HbpA enzyme and the corresponding biomimetic NADH compound, N-benzyl-1,4-dihdronicotinamide, 1b, for hydride transfers, was shown to readily occur. The in situ recycling of the reduced NADH biomimic 1b from 1a was accomplished with [Cp*Rh(bpy)H](Cl); however, productive coupling of this regeneration reaction to the enzymatic hydroxylation reaction was not totally successful, due to a deactivation process concerning the HbpA enzyme peripheral groups; i.e., -SH or -NH{sub 2} possibly reacting with the precatalyst, [Cp*Rh(bpy)(H{sub 2}O)](Cl){sub 2}, and thus inhibiting the co-factor regeneration process. The deactivation mechanism was studied, and a promising strategy of derivatizing these peripheral -SH or -NH{sub 2} groups with a polymer containing epoxide was successful in circumventing the undesired interaction between HbpA and the precatalyst. This latter strategy allowed tandem co-factor regeneration using 1a or 2a, [Cp*Rh(bpy)(H2O)](Cl){sub 2}, and formate ion, in conjunction with the polymer bound, FAD containing HbpA enzyme to provide the catechol product.
Date: March 9, 2004
Creator: Lutz, Jochen; Hollman, Frank; Ho, The Vinh; Schnyder, Adrian; Fish, Richard H. & Schmid, Andreas
Object Type: Article
System: The UNT Digital Library
www.fermiqcd.net (open access)

www.fermiqcd.net

FermiQCD is a C++ library for fast development of parallel lattice QCD applications. The expression FermiQCD Collaboration is used as a collective name to indicate both the users of the software and its contributors. One of the main differences between FermiQCD and libraries developed by other collaborations is that it follows an object oriented design as opposed to a procedural design. FermiQCD should not be identified exclusively with the implementation of the algorithms but, rather, with the strict specifications that define its Application Program Interface. One should think of FermiQCD as a language on its own (a superset of the C++ language), designed to describe Lattice QCD algorithms. The objects of the language include complex numbers (mdp-complex), matrices (mdp-matrix), lattices (mdp-lattice), fields (gauge-field, fermi-field, staggered-field), propagators (fermi-propagator) and actions. Algorithms written in terms of these objects are automatically parallel.
Date: March 9, 2004
Creator: al., Massino Di Pierro et
Object Type: Article
System: The UNT Digital Library

Anisotropic Flow in the Forward Directions

The STAR Forward TPCs (FTPCs) extend the STAR acceptance for charged particles into the region 2.5 < |eta| < 4.0. We see the first signal of directed flow (v{sub 1}) at RHIC energies. While v{sub 1} is consistent with zero in the central rapidity region it rises up to 2 percent at pseudorapidities of +-4. With this signal we can verify that elliptic flow (v{sub 2}) is in-plane. The measurement of v{sub 2} in the FTPCs confirms the falloff by a factor of about 2 compared to mid-rapidity previously seen by PHOBOS [1]. In addition we look for higher harmonics (v{sub n}, n>2) where in the case of v{sub 4} a signal is seen in the STAR TPC. With the available statistics for the FTPCs we give an upper limit for these harmonics, since the results agree with zero within the errors. However, the falloff of v{sub 4} from mid-rapidity to forward-rapidities appears to be faster than for v{sub 2}.[1] B.B. Back. Phys. Rev. Lett. 89, 222301 (2002)
Date: March 9, 2004
Creator: Oldenburg, Markus D. & Putschke, Jorn
Object Type: Poster
System: The UNT Digital Library
First upper limits from LIGO on gravitational wave bursts (open access)

First upper limits from LIGO on gravitational wave bursts

We report on a search for gravitational wave bursts using data from the first science run of the LIGO detectors. Our search focuses on bursts with durations ranging from 4 ms to 100 ms, and with significant power in the LIGO sensitivity band of 150 to 3000 Hz. We bound the rate for such detected bursts at less than 1.6 events per day at 90% confidence level. This result is interpreted in terms of the detection efficiency for ad hoc waveforms (Gaussians and sine-Gaussians) as a function of their root-sum-square strain h{sub rss}; typical sensitivities lie in the range h{sub rss} {approx} 10{sup -19} - 10{sup -17} strain/{radical}Hz, depending on waveform. We discuss improvements in the search method that will be applied to future science data from LIGO and other gravitational wave detectors.
Date: March 9, 2004
Creator: al., B. Abbott et
Object Type: Article
System: The UNT Digital Library
Gas Analysis of Geothermal Fluid Inclusions: A New Technology For Geothermal Exploration (open access)

Gas Analysis of Geothermal Fluid Inclusions: A New Technology For Geothermal Exploration

To increase our knowledge of gaseous species in geothermal systems by fluid inclusion analysis in order to facilitate the use of gas analysis in geothermal exploration. The knowledge of gained by this program can be applied to geothermal exploration, which may expand geothermal production. Knowledge of the gas contents in reservoir fluids can be applied to fluid inclusion gas analysis of drill chip cuttings in a similar fashion as used in the petroleum industry. Thus the results of this project may lower exploration costs both in the initial phase and lower drill hole completion costs. Commercial costs for fluid inclusion analysis done on at 20 feet intervals on chip samples for 10,000 ft oil wells is about $6,000, and the turn around time is a few weeks.
Date: March 9, 2004
Creator: Norman, David I. & Moore, Joseph
Object Type: Report
System: The UNT Digital Library
A High Order Mixed Vector Finite Element Method for Solving the Time Dependent Maxwell Equations on Unstructured Grids (open access)

A High Order Mixed Vector Finite Element Method for Solving the Time Dependent Maxwell Equations on Unstructured Grids

We present a mixed vector finite element method for solving the time dependent coupled Ampere and Faraday laws of Maxwell's equations on unstructured hexahedral grids that employs high order discretization in both space and time. The method is of arbitrary order accuracy in space and up to 5th order accurate in time, making it well suited for electrically large problems where grid anisotropy and numerical dispersion have plagued other methods. In addition, the method correctly models both the jump discontinuities and the divergence-free properties of the electric and magnetic fields, is charge and energy conserving, conditionally stable, and free of spurious modes. Several computational experiments are performed to demonstrate the accuracy, efficiency and benefits of the method.
Date: March 9, 2004
Creator: Rieben, R. N.; Rodrigue, G. H. & White, D. A.
Object Type: Article
System: The UNT Digital Library
Modeling of Fission Neutrons as a Signature for Detection of Highly Enriched Uranium (open access)

Modeling of Fission Neutrons as a Signature for Detection of Highly Enriched Uranium

We present the results of modeling intended to evaluate the feasibility of using neutrons from induced fission in highly enriched uranium (HEU) as a means of detecting clandestine HEU, even when it is embedded in absorbing surroundings, such as commercial cargo. We characterized radiation from induced fission in HEU, which consisted of delayed neutrons at all energies and prompt neutrons at energies above a threshold. We found that for the candidate detector and for the conditions we considered, a distinctive HEU signature should be detectable, given sufficient detector size, and should be robust over a range of cargo content. In the modeled scenario, an intense neutron source was used to induce fissions in a spherical shell of HEU. To absorb, scatter, and moderate the neutrons, we place one layer of simulated cargo between the source and target and an identical layer between the target and detector. The resulting neutrons and gamma rays are resolved in both time and energy to reveal the portion arising from fission. We predicted the dominant reaction rates within calcium fluoride and liquid organic scintillators. Finally, we assessed the relative effectiveness of two common neutron source energies.
Date: March 9, 2004
Creator: Wolford, J. K.; Frank, M. I. & Descalle, M.
Object Type: Article
System: The UNT Digital Library
Void hierarchy and cosmic structure (open access)

Void hierarchy and cosmic structure

Within the context of hierarchical scenarios of gravitational structure formation we describe how an evolving hierarchy of voids evolves on the basis of two processes, the void-in-void process and the void-in-cloud process. The related analytical formulation in terms of a two-barrier excursion problem leads to a self-similarly evolving peaked void size distribution.
Date: March 9, 2004
Creator: Weygaert, Rien van de & Sheth, Ravi
Object Type: Article
System: The UNT Digital Library