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UNT to work with six Metroplex elementary schools in national arts experiment designed to boost achievement (open access)

UNT to work with six Metroplex elementary schools in national arts experiment designed to boost achievement

An information release document in regards to six metroplex elementary schools plus thirty other schools nationwide were selected to participate as Arts Partner Schools in a $15 million experiment to reform education. The six schools will work with art educators at the University of North Texas, announced this month by the Annenberg Foundation, the Getty Education Institute for the Arts and the National Arts Education Consortium.
Date: March 27, 1997
Creator: LeMay, Nancy C.
System: The UNT Digital Library
Dynamics of N = 2 Supersymmetric Gauge Theories in Three Dimensions (open access)

Dynamics of N = 2 Supersymmetric Gauge Theories in Three Dimensions

We study the structure of the moduli spaces of vacua and superpotentials of N = 2 supersymmetric gauge theories in three dimensions. By analyzing the instanton corrections, we compute the exact superpotentials and determine the quantum Coulomb and Higgs branches of the theories in the weak coupling regions. We find candidates for non-trivial N = 2 superconformal field theories at the singularities of the moduli spaces. The analysis is carried out explicitly for gauge groups U(N{sub c}) and SU(N{sub c}) with N{sub f} flavors. We show that the field theory results are in complete agreement with the intersecting branes picture. We also compute the exact superpotentials for arbitrary gauge groups and arbitrary matter content.
Date: March 21, 1997
Creator: de Boer, J.; Hori, K. & Oz, Y.
System: The UNT Digital Library
Titanium Oxide Aerogel Prepared from Titanium Metal and Hydrogen Peroxide (open access)

Titanium Oxide Aerogel Prepared from Titanium Metal and Hydrogen Peroxide

The reaction of hydrogen peroxide with excess titanium metal produces rigid titanium oxide aquagels. Subsequent solvent exchanges with ethanol and carbon dioxide, and supercritical drying produces the corresponding aerogels. The aerogels are translucent yellow in appearance, are amorphous to X-rays, and have a BET surface area of 350 m{sup 2}/g. The empirical formula of the material, as prepared, is TiO{sub 3}H{sub 2.7}C{sub 0.35}. Infrared spectroscopy indicates the presence of peroxide and carbonate groups. the microstructure of the aerogel consists of a network of elongated particles 2-5 nm in diameter and tens of nm in length. Thermal treatment under argon at 473 K causes rapid decomposition of the aerogel, forming a blue-gray powder consisting of a mixture of rutile and anatase with a surface area of 80 m{sup 2}/g. Additional thermal treatment at 973 K under air forms predominantly rutile, with a surface area of 20 m{sup 2}/g.
Date: March 1, 1997
Creator: Ayers, M. R. & Hunt, A. J.
System: The UNT Digital Library
Analyses of the Grain Boundary Misorientation and Oxygen Content of Bulk Processed YBA(2)CU(3)O(7-D). (open access)

Analyses of the Grain Boundary Misorientation and Oxygen Content of Bulk Processed YBA(2)CU(3)O(7-D).

None
Date: March 31, 1997
Creator: Wang, J. Y.; King, A. H.; Zhu, Y.; Wang, Y. L. & Suenaga,M.
System: The UNT Digital Library
Covariant equations for the three-body bound state (open access)

Covariant equations for the three-body bound state

The covariant spectator (or Gross) equations for the bound state of three identical spin 1/2 particles, in which two of the three interacting particles are always on shell, are developed and reduced to a form suitable for numerical solution. The equations are first written in operator form and compared to the Bethe-Salpeter equation, then expanded into plane wave momentum states, and finally expanded into partial waves using the three-body helicity formalism first introduced by Wick. In order to solve the equations, the two-body scattering amplitudes must be boosted from the overall three-body rest frame to their individual two-body rest frames, and all effects which arise from these boosts, including Wigner rotations and p-spin decomposition of the shell-particle, are treated exactly. In their final form, the equations reduce to a coupled set of Faddeev-like double integral equations with additional channels arising from the negative p-spin states of the off-shell particle.
Date: March 1997
Creator: Stadler, A.; Gross, F. & Frank, M.
System: The UNT Digital Library
Computational tool for comparison of kinematic mechanisms and commonly used kinematic models (open access)

Computational tool for comparison of kinematic mechanisms and commonly used kinematic models

Accurate, reliable, and reproducible methods to measure the movements of human joints have been elusive. Currently, three-dimensional recording methods are used to track the motion of one segment relative to another as the joint moves. Six parameters describe the moving segment`s location and orientation relative to the reference segment: three translations (x, y, and z) and three rotations (yaw, pitch and roll) in the reference frame. The raw data can be difficult to interpret. For this reason, several methods have been developed to measure the motion of human joints and to describe the resulting data. For example, instant helical axes or screw deviation axes (Kinzell et al., 1972), the Joint Coordinate System of Grood and Suntay (1983), and the Euler angle method have been used to describe the movements of bones relative to each other. None of these methods takes into account the physical kinematic mechanism producing the joint motion. More recently, Lupichuk (1995) has developed an algorithm to find, for an arbitrary revolute, the axis` position and orientation in three- dimensional space. Each of these methods has advantages and disadvantages in analyzing joint kinematics. The authors have developed software to provide a means of comparing these methods for arbitrary, …
Date: March 1, 1997
Creator: Hollerbach, K.; Hollister, A.M. & Van Vorhis, R.L.
System: The UNT Digital Library
Effects of coprecipitation on uranium and plutonium concentrations in alkaline salt solutions (open access)

Effects of coprecipitation on uranium and plutonium concentrations in alkaline salt solutions

The chemistry of uranium and plutonium in conjunction with the storage, retrieval and treatment of high-level nuclear waste (HLW) has been the subject of increasing scrutiny due to concerns with nuclear criticality safety. Previous studies focused on determining the solubilities of plutonium and uranium in alkaline salt solutions that encompass the compositions present during storage and evaporation of fresh and aged. Recent studies extend the chemistry to include the effects of coprecipitation on the liquid phase concentrations of plutonium and uranium. Particle size, morphology and identification of crystalline phases in the precipitated solids as well as the plutonium and uranium dissolution characteristics upon dilution of the liquid phases were also determined.
Date: March 19, 1997
Creator: Hobbs, D. T.
System: The UNT Digital Library
Baryons and QCD (open access)

Baryons and QCD

The author presents an idiosyncratic view of baryons which calls for a marriage between quark-based and hadronic models of QCD. He advocates a treatment based on valence quark plus glue dominance of hadron structure, with the sea of q pairs (in the form of virtual hadron pairs) as important corrections.
Date: March 1, 1997
Creator: Isgur, Nathan
System: The UNT Digital Library
From the Feynman-Schwinger representation to the non-perturbative relativistic bound state interaction (open access)

From the Feynman-Schwinger representation to the non-perturbative relativistic bound state interaction

The authors write the 4-point Green function in QCD in the Feynman-Schwinger representation and show that all the dynamical information are contained in the Wilson loop average. They work out the QED case in order to obtain the usual Bethe-Salpeter kernel. Finally they discuss the QCD case in the non-perturbative regime giving some insight in the nature of the interaction kernel.
Date: March 1, 1997
Creator: Brambilla, N. & Vairo, A.
System: The UNT Digital Library
Non-perturbative dynamics of the heavy-light quark system in the non-recoil limit (open access)

Non-perturbative dynamics of the heavy-light quark system in the non-recoil limit

Starting from the relativistic gauge-invariant quark-antiquark Green function the authors obtain the relevant interaction in the one-body limit, which can be interpreted as the kernel of a non-perturbative Dirac equation. They study this kernel in different kinematic regions, reproducing, in particular, for heavy quark the potential case and sum rules results. They discuss the relevance of the result for heavy-light mesons and the relation with the phenomenological Dirac equations used up to now in the literature.
Date: March 1, 1997
Creator: Brambilla, N. & Vairo, A.
System: The UNT Digital Library
PVMPI provides interoperability between MPI implementations (open access)

PVMPI provides interoperability between MPI implementations

Presently, different MPI implementations cannot interoperate with each other. In order to do distributed computing across different vendors` machines now requires that a single MPI implementation, such as MPICH, be used rather than the vendors own optimized MPI implementations. This talk describes a software package called PVMPI the authors are developing that allows interoperability of vendors` optimized MPI versions. Their approach builds on the proven and widely ported Parallel Virtual Machine. The use of PVMPI is transparent to MPI applications and allows intercommunication via all the MPI point-to-point calls. PVMPI allows more flexible control over MPI applications than is currently indicated by the MPI-2 forum by providing access to all the process control and resource control functions available in the PVM virtual machine.
Date: March 1, 1997
Creator: Fagg, G. E.; Dongarra, J. J. & Geist, A.
System: The UNT Digital Library
PC Farms for Offline Event Reconstruction at Fermilab (open access)

PC Farms for Offline Event Reconstruction at Fermilab

Fermilab is investigating the use of PC`s for HEP computing. As a first step we have built a full offline environment under Linux on a set of Pentium (P5) and Pentium Pro (P6) machines (the ``PC Farm``). The Pythia simulation has been ported to run serially and in parallel (using CPS) on the PC Farm. Fermilab software products and CDF offline packages have also been ported to Linux. Run 1 CDF data has been analyzed on both Linux and SGI (Irix) with essentially identical results. The performance of the system is compared to results with commercial UNIX systems.
Date: March 1, 1997
Creator: Beretvas, A.
System: The UNT Digital Library
The Pierre Auger Observatory (open access)

The Pierre Auger Observatory

The Pierre Auger Observatory is an international collaboration for the detailed study of the highest energy cosmic rays. It will operate at two similar sites, one in the northern hemisphere and one in the southern hemisphere. The Observatory is designed to collect a statistically significant data set of events with energies greater than 10{sup 19} eV and with equal exposures for the northern and southern skies.
Date: March 1, 1997
Creator: Hojvat, C.
System: The UNT Digital Library
Contamination issues in superconducting cavity technology (open access)

Contamination issues in superconducting cavity technology

The application of radio-frequency superconductivity technology in particle accelerator projects has become increasingly evident in recent years. Several large scale projects around the world are either completed or close to completion, such as CEBAF, HERA, TRISTAN and LEP. And superconducting cavity technology is seriously being considered for future applications in linear colliders (TESLA), high current proton accelerators (APT, spallation neutron sources), muon colliders and free electron lasers for industrial application. The reason for this multitude of activities are matured technology based on a better understanding of the phenomena encountered in superconducting cavities and the influence of improved material properties and contamination and quality control measures.
Date: March 1, 1997
Creator: Kneisel, Peter
System: The UNT Digital Library
Training and qualification program for nuclear criticality safety technical staff. Revision 1 (open access)

Training and qualification program for nuclear criticality safety technical staff. Revision 1

A training and qualification program for nuclear criticality safety technical staff personnel has been developed and implemented. All personnel who are to perform nuclear criticality safety technical work are required to participate in the program. The program includes both general nuclear criticality safety and plant specific knowledge components. Advantage can be taken of previous experience for that knowledge which is portable such as performance of computer calculations. Candidates step through a structured process which exposes them to basic background information, general plant information, and plant specific information which they need to safely and competently perform their jobs. Extensive documentation is generated to demonstrate that candidates have met the standards established for qualification.
Date: March 5, 1997
Creator: Taylor, R.G. & Worley, C.A.
System: The UNT Digital Library
Overview of composite projects at the FAA Airworthiness Assurance Validation Center (open access)

Overview of composite projects at the FAA Airworthiness Assurance Validation Center

The Airworthiness Assurance NDI Validation Center (AANC) was established by the Federal Aviation Administration (FAA) William J. Hughes Technical Center at Sandia National Laboratories in 1991 to support nondestructive inspection (NDI) technology development and assessment. The evaluations are done using a variety of characterized test specimens and test beds including entire transport and commuter aircraft. Although the initial work at the Center concentrated on metallic structure, the FAA has more recently expanded the AANC`s charter to include projects directed at composite repair and inspection. The three projects briefly described in this paper are: (1) the validation and technology transfer of a thermographic techniques for composite inspection, (2) the development of generic composite laminate and honeycomb calibration reference standards, and (3) the certification of the use of boron epoxy doubler on a Lockheed L-1011.
Date: March 1, 1997
Creator: Shurtleff, William W.; Roach, Dennis P. & Valley, Michael T.
System: The UNT Digital Library
Temperature and moisture dependence of dielectric constant for silica aerogels (open access)

Temperature and moisture dependence of dielectric constant for silica aerogels

The dielectric constants of silica aerogels are among the lowest measured for any solid material. The silica aerogels also exhibit low thermal expansion and are thermally stable to temperatures exceeding 500{degrees}C. However, due to the open porosity and large surface areas for aerogels, their dielectric constants are strongly affected by moisture and temperature. This paper presents data for the dielectric constants of silica aerogels as a function of moisture content at 25{degrees}C, and as a function of temperature, for temperatures in the range from 25{degrees}C to 450{degrees}C. Dielectric constant data are also given for silica aerogels that are heat treated in dry nitrogen at 500{degrees}C, then cooled to 25{degrees}C for measurements in dry air. All measurements are made on bulk aerogel spheres at 22GHz microwave frequency, using a cavity perturbation method. The results of the dependence found here for bulk materials can be inferred to apply also to thin films of silica aerogels having similar nano-structures and densities.
Date: March 1, 1997
Creator: Hrubesh, L. H.
System: The UNT Digital Library
LATIS modeling of laser induced midplane and backplane spallation (open access)

LATIS modeling of laser induced midplane and backplane spallation

The computer code LATIS is used to simulate midplane and backplane spallation resulting from short pulsed laser absorption. A 1-D planar geometry is simulated with an exponential laser absorption profile. The laser pulse length is assumed to be much shorter than the sound transit time across the laser absorption length. The boundary conditions are a fixed front plane and free backplane (backplane spall) and a free front plane and a fixed midplane (midplane spall). The NBS/NRC equation of state for water is used with a self- consistent yet empirical material strength and failure model. The failure model includes the effects of void nucleation, growth and coalescence. Definite signatures of the nucleation and coalescence thresholds are found in the back surface motion for backplane spallation.
Date: March 5, 1997
Creator: Glinksky, M. E.; Bailey, D. S. & London, R. A.
System: The UNT Digital Library
Macroencapsulation of low-level debris waste with the phosphate ceramic process (open access)

Macroencapsulation of low-level debris waste with the phosphate ceramic process

Across the DOE complex, large quantities of contaminated debris and irradiated lead bricks require disposal. The preferred method for disposing of these wastes is macroencapsulation under U.S. Environmental Protection Agency Alternative Treatment Standards. Chemically bonded phosphate ceramics serve as a novel binder, developed at Argonne National Laboratory, for stabilizing and solidifying various low-level mixed wastes. Extremely strong, dense, and impervious to water intrusion, this material was developed with support from the U.S. Department of Energy`s Office of Science and Technology (DOE OST). In this investigation, CBPCs have been used to demonstrate macroencapsulation of various contaminated debris wastes, including cryofractured debris, lead bricks, and lead-lined plastic gloves. This paper describes the processing steps for fabricating the waste forms and the results of various characterizations performed on the waste forms. The conclusion is that simple and low-cost CBPCs are excellent material systems for macroencapsulating debris wastes.
Date: March 1, 1997
Creator: Singh, D.; Wagh, A.S.; Tlustochowicz, M. & Jeong, S.Y.
System: The UNT Digital Library
Design of a High Gradient Quadrupole for the LHC Interaction Regions (open access)

Design of a High Gradient Quadrupole for the LHC Interaction Regions

A collaboration of Fermilab, Lawrence Berkeley National Laboratory and Brookhaven National Laboratory is currently engaged in the design of a high gradient quadrupole suitable for use in the LHC interaction regions. The cold iron design incorporates a two-shell, cos2{theta} coil geometry with a 70 mm aperture. This paper summarizes the progress on a magnetic and mechanical design that meets the requirements of maximum gradient {>=}250 T/m, operation at 1.8K, high field quality and provision for adequate cooling in a high radiation environment.
Date: March 1, 1997
Creator: Bossert, R.; Gourlay, S.A.; Heger, T.; Huang, Y.; Kerby, J.; Lamm, M. J. et al.
System: The UNT Digital Library
Dumping pump and treat: rapid cleanups using thermal technology (open access)

Dumping pump and treat: rapid cleanups using thermal technology

Underground spills of volatile hydrocarbons are often difficult to clean up, especially if the contaminants are present in or below the water table as a separate liquid-organic phase. Excavating and treating the contaminated soil may not be practical or even possible if the affected zone is relatively deep. Merely pumping groundwater has proven to be ineffective because huge amounts of water must be flushed through the contaminated area to clean it; even then the contaminants may not be completely removed. Due to the low solubility of most common contaminants, such pump and treat systems can be expected to take decades to centuries to actually clean a site. Today, many sites are required to pump and treat contaminated groundwater even though there is no expectation that the site will be cleaned. In these cases, the pumps simply control the spread of the contaminant, while requiring a continuous flow of money, paperwork, and management attention. Although pump and treat systems are relatively inexpensive to operate, they represent along term cost. Most importantly, they rarely remove enough contaminant to change the property`s status. Although a pump and treat system can offer compliance in a regulatory sense, it doesn`t solve the site`s liability problem. …
Date: March 11, 1997
Creator: Newmark, R. L. & Aines, R. D.
System: The UNT Digital Library
Gamma ray scanner systems for nondestructive assay of heterogeneous waste barrels (open access)

Gamma ray scanner systems for nondestructive assay of heterogeneous waste barrels

Traditional gamma safeguards measurements have usually been performed using a segmented gamma scanning (SGS) system. The accuracy of this technique relies on the assumption that the sample matrix and the activity are both uniform for a segment. Waste barrels are often highly heterogeneous, span a wide range of composition and matrix type. The primary sources of error are all directly or indirectly related to a non-uniform measurement response associated with unknown radioactive source spatial distribution and heterogeneity of the matrix. These errors can be significantly reduced by some imaging techniques that measure exact spatial locations of sources and attenuation maps. In this paper we describe a joint R&D effort between the Lawrence Livermore National Laboratory (LLNL) and the Institute of Nuclear Techniques (INT) of the Technical University, Budapest, to compare results obtained by two different gamma-ray nondestructive assay (NDA) systems used for imaging waste barrels. The basic principles are the same, but the approaches are different. Key factors to judge the adequacy of a method are the detection limit and the accuracy. Test drums representing waste to be measured are used to determine basic parameters of these techniques.
Date: March 25, 1997
Creator: Martz, H. E.; Decman, B. J.; Roberson, G. P. & Levai, F.
System: The UNT Digital Library
Defects that control the properties of Tl- and Hg-based superconductors (open access)

Defects that control the properties of Tl- and Hg-based superconductors

Defects that affect T{sub c} in Tl{sub 2}Ba{sub 2}CuO{sub 6+{delta}} and HgBa{sub 2}CuO{sub 4+{delta}} and HgBa{sub 2}CuO{sub 4+{delta}} have been characterized by neutron powder diffraction. In Tl{sub 2}Ba{sub 2}CuO{sub 6+{delta}}, the dominant defect is interstitial oxygen between the two Tl-O planes, but Cu substitution on the Tl site also affects properties and there is evidence for a second oxygen defect for compositions in the vicinity of maximum {Tc}. In HgBa{sub 2}CuO{sub 4+{delta}}, there are two competing oxygen defects in the Hg layer. The relative concentrations of these defects switches upon passing from the underdoped region, through the maximum {Tc}, to the overdoped region. This remarkable behavior could result from a change in the topology of the Fermi surface upon passing through the van Hove singularity.
Date: March 1, 1997
Creator: Jorgensen, J. D.; Chmaissem, O.; Hinks, D. G.; Mitchell, J. F.; Wagner, J. L.; Jensen, W. R. et al.
System: The UNT Digital Library
Using seismology for regional confidence building (open access)

Using seismology for regional confidence building

Confidence building between regional parties can be facilitated through cooperative seismological research activities. Shared data, facilities, technology, and research results can (1) assure participants that nuclear testing is not taking place, (2) provide information that can be used to characterize the geophysical parameters of a region for earthquake hazard mitigation, and (3) support basic seismic research.
Date: March 1997
Creator: Nakanishi, K. K.
System: The UNT Digital Library