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A Roadmap to Recent Developments in the Theory of Turbulent Generation of Long-wavelength Flows

Description: A brief overview is given of recent results in the theory of turbulent generation of long-wavelength fluctuations; references are provided to more detailed calculations in the literature. Emphasis is placed on conceptual foundations and technical tools, which can be simply illustrated by studies of the scalar (one-field) generalized Hasegawa-Mima equation. Then a functional Hamiltonian formalism is discussed as a way of efficiently handling systems of coupled fields. Casimir invariants are shown to be the appropriate ''plasmon densities''; a tensor spectral-balance equation builds in the conservation constraints automatically. A concise expression can be obtained for the nonlinear growth rate in terms of the spectral density, a tensor generalization of the triad interaction time, and the metric tensor and structure constants of the Hamiltonian structure.
Date: March 16, 2004
Creator: Krommes, John A.
Partner: UNT Libraries Government Documents Department

YbiV from E. coli K12 is a HAD phosphatase

Description: The protein YbiV from Escherichia coli K12 MG1655 is a hypothetical protein with sequence homology to the haloacid dehalogenase (HAD) superfamily of proteins. Although numerous members of this family have been identified, the functions of few are known. Using the crystal structure, sequence analysis, and biochemical assays, we have characterized ybiV as a HAD phosphatase. The crystal structure of YbiV reveals a two domain protein, one with the characteristic HAD hydrolase fold, the other an inserted a/b fold. In an effort to understand the mechanism we also solved and report the structures of YbiV in complex with beryllofluoride (BeF3-) and aluminum trifluoride (AlF3) which have been shown to mimic the phosphorylated intermediate and transition state for hydrolysis, respectively, in analogy to other HAD phosphatases. Analysis of the structures reveals the substrate binding cavity, which is hydrophilic in nature. Both structure and sequence homology indicate ybiV may be a sugar phosphatase, which is supported by biochemical assays which measured the release of free phosphate on a number of sugar-like substrates. We also investigated available genomic and functional data in an effort to determine the physiological substrate.
Date: March 16, 2004
Creator: Roberts, Anne; Lee, Seok-Yong; McCullagh, Emma; Silversmith, Ruth E. & Wemmer, David E.
Partner: UNT Libraries Government Documents Department

Properties of charmonium in lattice QCD with 2+1 flavors of improved staggered sea quarks

Description: We use the dynamical gluon configurations provided by the MILC collaboration in a study of the charmonium spectrum and {psi} leptonic width. We examine sea quark effects on mass splitting and on the leptonic decay matrix element for light masses as low as m{sub s}/5, while keeping the strange quark mass fixed and the lattice spacing nearly constant.
Date: March 16, 2004
Creator: al., Massimo Di Pierro et
Partner: UNT Libraries Government Documents Department

Applying synchrotron phase measurement to the estimation of maximum beam intensity in the Fermilab Booster

Description: It is important to have experimental methods to estimate the maximum beam intensity for the Fermilab Booster as objective input into long term program commitments. An important existing limit is set by the available rf power. This limit is difficult to set a priori, because the real longitudinal impedance is not well known. The synchrotron phase at transition crossing was measured using both the mountain range plot and the direct phase measurement of the RF accelerating voltage relative to the beam, and results were consistent. They were applied to predict 6 x 10{sup 12} maximum Booster beam intensity with present running conditions.
Date: March 16, 2004
Creator: Yang, Xi & MacLachlan, James
Partner: UNT Libraries Government Documents Department

Enhanced vibrations at surfaces with back-bonds nearly parallel to the surface

Description: It has been discovered that several very different surfaces exhibit a common property: unusually large vibration amplitudes of the outermost atoms, well beyond the enhancement normally expected at typical clean surfaces. These special surfaces are: ice H2O(0001), alpha-Al2O3(0001), alpha-Ga(010) and Si(111)-(2x1). The root-mean-square vibration amplitudes in these surfaces are at least double the bulk values. The common cause that may explain these vibration amplitudes is that the surface atoms (or molecules in the case of ice) only have back-bonds that are nearly parallel to the surface. In this geometry, vibrations, especially perpendicular to the surface, involve primarily bond bending rather than bond stretching/compression: since bond bending is relatively soft, the corresponding vibration modes can have larger amplitudes. It is suggested that theory examine and confirm this cause of enhanced surface vibration amplitudes, and explore its implication for other phenomena such as adsorption and catalysis.
Date: March 16, 2004
Creator: Van Hove, M.A.
Partner: UNT Libraries Government Documents Department

Neutral Particle Analyzer Diagnostic on NSTX

Description: The Neutral Particle Analyzer (NPA) diagnostic on the National Spherical Torus Experiment (NSTX) utilizes a PPPL-designed E||B spectrometer that measures the energy spectra of minority hydrogen and bulk deuterium species simultaneously with 39 energy channels per mass specie and a time resolution of 1 ms. The calibrated energy range is E = 0.5-150 keV and the energy resolution varies from AE/E = 3-7% over the surface of the microchannel plate detector.
Date: March 16, 2004
Creator: Medley, S.S. & Roquemore, A.L.
Partner: UNT Libraries Government Documents Department

Thermodynamic Properties of Quinoxaline-1,4-Dioxide Derivatives: A Combined Experimental and Computational Study

Description: Article on thermodynamic properties of quinoxaline-1,4-dioxide derivatives and a combined experimental and computational study.
Date: March 16, 2004
Creator: Silva, Maria D. M. C. Ribeiro da; Gomes, José R. B.; Gonçalves, Jorge M.; Sousa, Emanuel A.; Pandey, Siddharth & Acree, William E. (William Eugene)
Partner: UNT College of Arts and Sciences

Information Security: Continued Efforts Needed to Sustain Progress in Implementing Statutory Requirements

Description: Testimony issued by the General Accounting Office with an abstract that begins "For many years, GAO has reported on the widespread negative impact of poor information security within federal agencies and has identified it as a governmentwide high-risk issue since 1997. Legislation designed to improve information security was enacted in October 2000. It was strengthened in December 2002 by new legislation, the Federal Information Security Management Act of 2002 (FISMA), which incorporated important new requirements. This testimony discusses (1) the Office of Management and Budget's (OMB) recent report to the Congress required by FISMA on the government's overall information security posture, (2) the reported status of efforts by 24 of the largest agencies to implement federal information security requirements, (3) opportunities for improving the usefulness of performance measurement data, and (4) progress by the National Institute of Standards and Technology (NIST) to develop related standards and guidance."
Date: March 16, 2004
Creator: United States. General Accounting Office.
Partner: UNT Libraries Government Documents Department

Homeland Security: Risk Communication Principles May Assist in Refinement of the Homeland Security Advisory System

Description: Testimony issued by the General Accounting Office with an abstract that begins "Established in March 2002, the Homeland Security Advisory System was designed to disseminate information regarding the risk of terrorist acts to federal, state, and local government agencies, private industry, and the public. However, this system generated questions among these entities regarding whether they were receiving the necessary information to respond appropriately to heightened alerts. GAO obtained information on how the Homeland Security Advisory System operates, including the process used to notify federal, state, and local government agencies, private industry, and the public of changes in the threat level. GAO also reviewed literature on risk communication to identify principles and factors to be considered when determining when, what, and how information should be disseminated about threat level changes. Additionally, GAO researched what type of information had been provided to federal, state, and local agencies, private industry, and the public regarding terrorist threats. GAO also identified protective measures that were suggested for these entities to implement during code-orange alerts. Last, GAO identified additional information requested by recipients of threat information."
Date: March 16, 2004
Creator: United States. General Accounting Office.
Partner: UNT Libraries Government Documents Department

Focusing Hard X-rays at Current and Future Light Sources for Microscopy and High-Power Applications

Description: The field of x-ray optics struggles to develop optical systems with the versatility and sophistication of their visible light counterparts. The advent of fourth-generation light sources will make the struggle even more difficult. Fourth-generation light sources include laser/plasma sources, x-ray Free Electron Lasers (FEL), inverse Compton scattering sources, and the National Ignition Facility. LCLS, (Linac Coherent Light Source), and its European cousin, will be the first of the x-ray FELs. The LCLS, to be built at the Stanford Linear Accelerator Center (SLAC), takes advantage of the existing SLAC linear accelerator to send intense, low emittance electron bunches through a 100 m long undulator structure. Through a process called SASE (Self Amplification of Spontaneous Emission) the electrons interact with the radiation fields they produce while in the undulator causing them to collect into micro bunches that emit coherent light. In the case of the LCLS the coherent radiation will have a wavelength in the x-ray regime, and will be tunable from 1.5 to 15 {angstrom}. The LCLS will deliver x-rays in individual coherent packages lasting < 300 fs, making the LCLS a very important source for studying short time phenomenon and for performing high-resolution x-ray structural analysis of molecular sized systems. Moreover, each coherent packet packs 10{sup 12} photons in a very small volume of space- time; the interaction of this packet with matter, and the subsequent aftermath offer new opportunities in physics. To make full use of the LCLS, experimenters must be able to manipulate and focus the LCLS beam, and therefore must contend with the fact that the unprecedented energy density per unit area in the FEL beam is enough to melt most materials in a single pulse. Take the example of the Warm Dense Matter experiment, in which LLNL researchers hope to use a focused LCLS beam to ...
Date: March 16, 2004
Creator: Bionta, R M
Partner: UNT Libraries Government Documents Department

Fermion Monte Carlo Calculations on Liquid-3He

Description: Methods and results for calculations of the ground state energy of the bulk system of {sup 3}He atoms are discussed. Results are encouraging: they believe that they demonstrate that their methods offer a solution of the ''fermion sign problem'' and the possibility of direct computation of many-fermion systems with no uncontrolled approximations. Nevertheless, the method is still rather inefficient compared with variational or fixed-node approximate methods. There appears to be a significant populations size effect. The situation is improved by the inclusion of ''Second Stage Importance Sampling'' and of ''Acceptance/Rejection'' adapted to their needs.
Date: March 16, 2004
Creator: Kalos, M H; Colletti, L & Pederiva, F
Partner: UNT Libraries Government Documents Department

Design and testing of a control strategy for a large naturallyventilated office building

Description: The design for the new Federal Building for San Franciscoincludes an office tower that is to be naturally ventilated. Each flooris designed to be cross-ventilated, through upper windows that arecontrolled by the building management system (BMS). Users have controlover lower windows, which can be as much as 50 percent of the totalopenable area. There are significant differences in the performance andthe control of the windward and leeward sides of the building, andseparate monitoring and control strategies are determined for each side.The performance and control of the building has been designed and testedusing a modified version of EnergyPlus. Results from studies withEnergyPlus and CFD are used in designing the control strategy. EnergyPluswas extended to model a simplified version of the airflow patterndetermined using CFD. Wind-driven cross-ventilation produces a main jetthrough the upper openings of the building, across the ceiling from thewindward to the leeward side. Below this jet, the occupied regions aresubject to a recirculating air flow. Results show that temperatureswithin the building are predicted to be satisfactory, provided a suitablecontrol strategy is implemented uses night cooling in periods of hotweather. The control strategy has 10 window opening modes. EnergyPlus wasextended to simulate the effects of these modes, and to assess theeffects of different forms of user behavior. The results show how userbehavior can significantly influence the buildingperformance.
Date: March 16, 2004
Creator: Carrilho da Graca, Guilherme; Linden, Paul F. & Haves, Philip
Partner: UNT Libraries Government Documents Department

21st Century Community Learning Centers in P.L. 107-110: Background and Funding

Description: This report summarizes the major provisions of the reauthorized 21st Century Community Learning Centers (21st CCLC) program. It includes sections on fundings, national reservations, formula grants to states, competitive local grants, history, program effectiveness, and relevant legislation in the 107th Congress.
Date: March 16, 2004
Creator: McCallion, Gail
Partner: UNT Libraries Government Documents Department

Parliamentary Reference Sources: House of Representatives

Description: This report discusses the availability and format of three types of parliamentary reference materials: official sources such as the House Rules and Manual and the published precedents; publications of committees and offices of the House; and documents prepared by House party and leadership organizations. It also reviews some principles of House parliamentary procedure that are important to consider when using information from parliamentary reference sources.
Date: March 16, 2004
Creator: Carr, Thomas P.
Partner: UNT Libraries Government Documents Department

Comparison of two up-scaling methods in poroelasticity and its generalizations

Description: Two methods of up-scaling coupled equations at the microscale to equations valid at the mesoscale and/or macroscale for fluid-saturated and partially saturated porous media are discussed, compared, and contrasted. The two methods are: (1) two-scale and multiscale homogenization, and (2) volume averaging. Both these methods have advantages for some applications and disadvantages for others. For example, homogenization methods can give formulas for coefficients in the up-scaled equations, whereas volume averaging methods give the form of the up-scaled equations but generally must be supplemented with physical arguments and/or data in order to determine the coefficients. Homogenization theory requires a great deal of mathematical insight from the user in order to choose appropriate scalings for use in the resulting power-law expansions, while volume averaging requires more physical insight to motivate the steps needed to find coefficients. Homogenization often is performed on periodic models, while volume averaging does not require any assumption of periodicity and can therefore be related very directly to laboratory and/or field measurements. Validity of the homogenization process is often limited to specific ranges of frequency - in order to justify the scaling hypotheses that must be made - and therefore cannot be used easily over wide ranges of frequency. However, volume averaging methods can quite easily be used for wide band data analysis.
Date: March 16, 2004
Creator: Berryman, J G
Partner: UNT Libraries Government Documents Department

The effect of a short wavelength mode on the evolution of a long wavelength perturbation driven by a strong blast wave

Description: Shock-accelerated material interfaces are potentially unstable to both the Richtmyer-Meshkov and Rayleigh-Taylor instabilities. Shear that develops along with these instabilities in turn drives the Kelvin-Helmholtz instability. When driven by strong shocks, the evolution and interaction of these instabilities is further complicated by compressibility effects. In this paper, we present a computational study of the formation of jets at strongly driven hydrodynamically unstable interfaces, and the interaction of these jets with one another and with developing spikes and bubbles. This provides a nonlinear spike-spike and spike-bubble interaction mechanism that can have a significant impact on the large-scale characteristics of the mixing layer. These interactions result in sensitivity to the initial perturbation spectrum, including the relative phases of the various modes, that persists long into the nonlinear phase of instability evolution. We describe implications for instability growth rates, the bubble merger process, and the degree of mix in the layer. Finally, we consider results from relevant deceleration RT experiments, performed on OMEGA, to demonstrate some of these effects.
Date: March 16, 2004
Creator: Miles, A R; Edwards, M; Blue, B; Hansen, J F; Robey, H F; Drake, R P et al.
Partner: UNT Libraries Government Documents Department

Warped Supersymmetric Unification with Non-Unified Superparticle Spectrum

Description: We present a new supersymmetric extension of the standard model. The model is constructed in warped space, with a unified bulk symmetry broken by boundary conditions on both the Planck and TeV branes. In the supersymmetric limit, the massless spectrum contains exotic colored particles along with the particle content of the minimal supersymmetric standard model (MSSM). Nevertheless, the model still reproduces the MSSM prediction for gauge coupling unification and does not suffer from a proton decay problem. The exotic states acquire masses from supersymmetry breaking, making the model completely viable, but thereis still the possibility that these states will be detected at the LHC. The lightest of these states is most likely A_5^XY, the fifth component of the gauge field associated with the broken unified symmetry. Because supersymmetry is broken on the SU(5)-violating TeV brane, the gaugino masses generated at the TeV scale are completely independent of one another. We explore some of the unusual features that the superparticle spectrum might have as a consequence.
Date: March 16, 2004
Creator: Nomura, Yasunori; Tucker-Smith, David & Tweedie, Brock
Partner: UNT Libraries Government Documents Department

Matter Unification in Warped Supersymmetric SO(10)

Description: We construct models of warped unification with a bulk SO(10) gauge symmetry and boundary conditions that preserve the SU(4)_C x SU(2)_L x SU(2)_R Pati-Salam gauge group (422). In the dual 4D description, these models are 422 gauge theories in which the apparent unification of gauge couplings in the minimal supersymmetric standard model is explained as a consequence of strong coupling in the ultraviolet. The weakness of the gauge couplings at low energies is ensured in this 4D picture by asymptotically non-free contributions from the conformal sector, which are universal due to an approximate SO(10) global symmetry. The 422 gauge symmetry is broken to the standard model group by a simple set of Higgs fields. An advantage of this setup relative to SU(5) models of warped unification is that matter is automatically required to fill out representations of 422, providing an elegant understanding of the quantum numbers of the standard-model quarks and leptons. The models also naturally incorporate the see-saw mechanism for neutrino masses and bottom-tau unification. Finally, they predict a rich spectrum of exotic particles near the TeV scale, including states with different quantum numbers than those that appear in SU(5) models.
Date: March 16, 2004
Creator: Nomura, Yasunori & Tucker-Smith, David
Partner: UNT Libraries Government Documents Department