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Horizontal gene transfer and the evolution of transcriptionalregulation in Escherichia coli

Description: Background: Most bacterial genes were acquired by horizontalgene transfer from other bacteria instead of being inherited bycontinuous vertical descent from an ancient ancestor}. To understand howthe regulation of these {acquired} genes evolved, we examined theevolutionary histories of transcription factors and of regulatoryinteractions from the model bacterium Escherichia coli K12. Results:Although most transcription factors have paralogs, these usually arose byhorizontal gene transfer rather t… more
Date: December 20, 2007
Creator: Price, Morgan N.; Dehal, Paramvir S. & Arkin, Adam P.
Partner: UNT Libraries Government Documents Department
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BDDC for nonsymmetric positive definite and symmetric indefinite problems

Description: The balancing domain decomposition methods by constraints are extended to solving both nonsymmetric, positive definite and symmetric, indefinite linear systems. In both cases, certain nonstandard primal constraints are included in the coarse problems of BDDC algorithms to accelerate the convergence. Under the assumption that the subdomain size is small enough, a convergence rate estimate for the GMRES iteration is established that the rate is independent of the number of subdomains and depends … more
Date: December 10, 2008
Creator: Tu, Xuemin & Li, Jing
Partner: UNT Libraries Government Documents Department
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Oxidation of alloys targeted for advanced steam turbines

Description: Ultra supercritical (USC) power plants offer the promise of higher efficiencies and lower emissions. Current goals of the U.S. Department of Energy’s Advanced Power Systems Initiatives include coal generation at 60% efficiency, which would require steam temperatures of up to 760°C. This research examines the steamside oxidation of alloys for use in USC systems, with emphasis placed on applications in high- and intermediate-pressure turbines.
Date: March 12, 2006
Creator: Holcomb, G. R.; Covino, B. S., Jr.; Bullard, S. J.; Ziomek-Moroz, M. & Alman, D. E.
Partner: UNT Libraries Government Documents Department
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Time Reversal Violation

Description: This talk briefly reviews three types of time-asymmetry in physics, which I classify as universal, macroscopic and microscopic. Most of the talk is focused on the latter, namely the violation of T-reversal invariance in particle physics theories. In sum tests of microscopic T-invariance, or observations of its violation, are limited by the fact that, while we can measure many processes, only in very few cases can we construct a matched pair of process and inverse process and observe it with suf… more
Date: January 27, 2009
Creator: Quinn, H.
Partner: UNT Libraries Government Documents Department
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Measurement of Fast Voltage Transients in High-Performance Nb3Sn Magnets

Description: The Superconducting Magnet group at Lawrence Berkeley National Laboratory has been developing Nb{sub 3}Sn high-field accelerator magnet technology for the last fifteen years. In order to support the magnet R&D effort, we are developing a diagnostic system that can help identify the causes of performance limiting quenches by recording small flux-changes within the magnet prior to quench-onset. These analysis techniques were applied to the test results from recent Nb{sub 3}Sn magnets. This pa… more
Date: June 1, 2008
Creator: Lietzke, A. F.; Sabbi, G. L.; Ferracin, P.; Caspi, S.; Zimmerman, S.; Joseph, J. et al.
Partner: UNT Libraries Government Documents Department
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Mechanical and charge transport properties of alkanethiol self-assembled monolayers on Au (111) surface: The Role of Molecular Tilt

Description: The relationship between charge transport and mechanical properties of alkanethiol self-assembled monolayers (SAM) on Au(111) films has been investigated using an atomic force microscope with a conductive tip. Molecular tilts induced by the pressure applied by the tip cause stepwise increases in film conductivity. A decay constant {beta} = 0.57 {+-} 0.03 {angstrom}{sup -1} was found for the current passing through the film as a function of tip-substrate separation due to this molecular tilt. Th… more
Date: November 12, 2007
Creator: Mulleregan, Alice; Qi, Yabing; Ratera, Imma; Park, Jeong Y.; Ashby, Paul D.; Quek, Su Ying et al.
Partner: UNT Libraries Government Documents Department
open access

THz radiation as a bunch diagnostic forlaser-wakefield-accelerated electron bunches

Description: Experimental results are reported from two measurementtechniques (semiconductor switching and electro-optic sampling) thatallow temporal characterization of electron bunches produced by alaser-driven plasma-based accelerator. As femtosecond electron bunchesexit the plasma-vacuum interface, coherent transition radiation (at THzfrequencies) is emitted. Measuring the properties of this radiationallows characterization of the electron bunches. Theoretical work on theemission mechanism is represente… more
Date: February 15, 2006
Creator: van Tilborg, J.; Schroeder, C. B.; Filip, C. V.; Toth, Cs.; Geddes, C. G. R.; Fubiani, G. et al.
Partner: UNT Libraries Government Documents Department
open access

Initial Operation of the High Temperature Electrolysis Integrated Laboratory Scale Experiment at INL

Description: An integrated laboratory scale, 15 kW high-temperature electrolysis facility has been developed at the Idaho National Laboratory under the U.S. Department of Energy Nuclear Hydrogen Initiative. Initial operation of this facility resulted in over 400 hours of operation with an average hydrogen production rate of approximately 0.9 Nm3/hr. The integrated laboratory scale facility is designed to address larger-scale issues such as thermal management (feed-stock heating, high-temperature gas handlin… more
Date: June 1, 2008
Creator: Stoots, C. M.; O'Brien, J. E.; Condie, K. G.; Herring, J. S. & Hartvigsen, J. J.
Partner: UNT Libraries Government Documents Department
open access

Transmission Electron Microscopy Study of Nonpolar a-Plane GaNGrown by Pendeo-Epitaxy on (112_0) 4H-SiC

Description: Pendeo-epitaxy has been applied to nonpolar a-plane GaN layers in order to observe if such process will lead to defect reduction in comparison with direct growth on this plane. Uncoalesced and coalesced a-plane GaN layers with thicknesses 2{micro}m and 12{micro}m, respectively have been studied by conventional and high resolution electron microscopy. The following structural defects have been observed in pendeo-epitaxial layers: (1) basal stacking faults, (2) threading dislocations and (3) pris… more
Date: March 10, 2005
Creator: Zakharov, D. N.; Liliental-Weber, Z.; Wagner, B.; Reitmeier, Z. J.; Preble, E. A. & Davis, R. F.
Partner: UNT Libraries Government Documents Department
open access

Three-dimensional lithographically-defined organotypic tissue arrays for quantitative analysis of morphogenesis and neoplastic progression

Description: Here we describe a simple micromolding method to construct three-dimensional arrays of organotypic epithelial tissue structures that approximate in vivo histology. An elastomeric stamp containing an array of posts of defined geometry and spacing is used to mold microscale cavities into the surface of type I collagen gels. Epithelial cells are seeded into the cavities and covered with a second layer of collagen. The cells reorganize into hollow tissues corresponding to the geometry of the caviti… more
Date: February 13, 2008
Creator: Nelson, Celeste M.; Inman, Jamie L. & Bissell, Mina J.
Partner: UNT Libraries Government Documents Department
open access

Z' Coupling Information From LHeC

Description: No Description Available.
Date: April 4, 2008
Creator: Rizzo, Thomas G.
Partner: UNT Libraries Government Documents Department
open access

R. Bruce Merrifield and Solid-Phase Peptide Synthesis: A Historical Assessment

Description: Bruce Merrifield, trained as a biochemist, had to address three major challenges related to the development and acceptance of solid-phase peptide synthesis (SPPS). The challenges were (1) to reduce the concept of peptide synthesis on a insoluble support to practice, (2) overcome the resistance of synthetic chemists to this novel approach, and (3) establish that a biochemist had the scientific credentials to effect the proposed revolutionary change in chemical synthesis. How these challenges wer… more
Date: December 4, 2007
Creator: Mitchell, A R
Partner: UNT Libraries Government Documents Department
open access

Differentiating neutrino models on the basis of $\theta_{13}$ and lepton flavor violation

Description: The authors show how models of neutrino masses and mixings can be differentiated on the basis of their predictions for {theta}{sub 13} and lepton flavor violation in radiative charged lepton decays and {mu} - e conversion. They illustrate the lepton flavor violation results for five predictive SO(10) SUSY GUT models and point out the relative importance of their heavy right-handed neutrino mass spectra and {theta}{sub 13} predictions.
Date: March 1, 2008
Creator: Albright, Carl H.
Partner: UNT Libraries Government Documents Department
open access

Resonant Soft X-Ray Contrast Variation Methods as Composition-Specific Probes of Thin Polymer Film Structure

Description: We have developed complementary soft x-ray scattering and reflectometry techniques that allow for the morphological analysis of thin polymer films without resorting to chemical modification or isotopic 2 labeling. With these techniques, we achieve significant, x-ray energy-dependent contrast between carbon atoms in different chemical environments using soft x-ray resonance at the carbon edge. Because carbon-containing samples absorb strongly in this region, the scattering length density depends… more
Date: April 4, 2008
Creator: Welch, Cynthia; Welch, Cynthia F.; Hjelm, Rex P.; Mang, Joseph T.; Hawley, Marilyn E.; Wrobleski, Debra A. et al.
Partner: UNT Libraries Government Documents Department
open access

Operation of a Free-Electron Laser from the Extreme Ultraviolet to the Water Window

Description: We report results on the performance of a free-electron laser operating at a wavelength of 13.7 nm where unprecedented peak and average powers for a coherent extreme-ultraviolet radiation source have been measured. In the saturation regime, the peak energy approached 170 {micro}J for individual pulses, and the average energy per pulse reached 70 {micro}J. The pulse duration was in the region of 10 fs, and peak powers of 10 GW were achieved. At a pulse repetition frequency of 700 pulses per seco… more
Date: December 17, 2007
Creator: Ackermann, W.; Asova, G.; Ayvazyan, V.; Azima, A.; Baboi, N.; Bahr, J. et al.
Partner: UNT Libraries Government Documents Department
open access

The U.S. Department of Energy's Aerial Measuring System (AMS)

Description: For nearly 40 years, aerial radiological search and survey missions have been performed by the United States Department of Energy's (USDOE) Remote Sensing Laboratory (RSL). Originally created in 1967 as Aerial Measurement Operations (AMO), the AMS mission has expanded to include acquiring baseline measurements, performing periodic area monitoring, and responding to radiological emergencies. In an accident scenario, AMS fixed-wing and/or rotary-wing systems can be deployed to map radiological de… more
Date: March 1, 2008
Creator: Marianno, Craig
Partner: UNT Libraries Government Documents Department
open access

Magnet R&D for the US LHC Accelerator Research Program (LARP)

Description: In 2004, the US DOE established the LHC Accelerator Research Program (LARP) with the goal of developing a technology base for future upgrades of the LHC. The focus of the magnet program, which is a collaboration of three US laboratories, BNL, FNAL and LBNL, is on development of high gradient quadrupoles using Nb{sub 3}Sn superconductor. Other program components address issues regarding magnet design, radiation-hard materials, long magnet scale-up, quench protection, fabrication techniques and c… more
Date: June 1, 2006
Creator: Gourlay, S. A.; Ambrosio, G.; Andreev, N.; Anerella, M.; Barzi, E.; Bossert, R. et al.
Partner: UNT Libraries Government Documents Department
open access

Future possibilities with Fermilab neutrino beams

Description: We will start with a brief overview of neutrino oscillation physics with emphasis on the remaining unanswered questions. Next, after mentioning near future reactor and accelerator experiments searching for a non zero {theta}{sub 13}, we will introduce the plans for the next generation of long-baseline accelerator neutrino oscillation experiments. We will focus on experiments utilizing powerful (0.7-2.1 MW) Fermilab neutrino beams, either existing or in the design phase.
Date: January 1, 2008
Creator: Saoulidou, Niki
Partner: UNT Libraries Government Documents Department
open access

X-ray spectroscopic study of the charge state and local orderingof room-temperature ferromagnetic Mn oped ZnO

Description: The charge state and local ordering of Mn doped into a pulsed laser deposited single-phase thin film of ZnO are investigated by using X-ray absorption spectroscopy at the O K-, Mn K- and L-edges, and X-ray emission spectroscopy at the O K- and Mn L-edge. This film is found to be ferromagnetic at room temperature. EXAFS measurement shows that Mn{sup 2+} replaces Zn site in tetrahedral symmetry, and there is no evidence for either metallic Mn or MnO in the film. Upon Mn doping, the top of O 2p va… more
Date: August 7, 2007
Creator: Guo, J.-H.; Gupta, Amita; Sharma, Parmanand; Rao, K.V.; Marcus,M.A.; Dong, C.L. et al.
Partner: UNT Libraries Government Documents Department
open access

Plan for Using Solar-Powered Jack Pumps to Sample Groundwater at the Nevada Test Site

Description: Groundwater is sampled from 39 monitoring wells on the Nevada Test Site (NTS) as part of the Routine Radiological Environmental Monitoring Program. Many of these wells were not designed or constructed for long-term groundwater monitoring. Some have extensive completion zones and others have obstructions such as pumps and tubing. The high-volume submersible pumps in some wells are unsuitable for long-term monitoring and result in large volumes of water that may have to be contained and character… more
Date: May 3, 2007
Creator: David Hudson, Charles Lohrstorfer, Bruce Hurley
Partner: UNT Libraries Government Documents Department
open access

Book Review Geostatistical Analysis of Compositional Data

Description: Compositional data are represented as vector variables with individual vector components ranging between zero and a positive maximum value representing a constant sum constraint, usually unity (or 100 percent). The earth sciences are flooded with spatial distributions of compositional data, such as concentrations of major ion constituents in natural waters (e.g. mole, mass, or volume fractions), mineral percentages, ore grades, or proportions of mutually exclusive categories (e.g. a water-oil-r… more
Date: March 26, 2007
Creator: Carle, S F
Partner: UNT Libraries Government Documents Department
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Multi-Megajoule NIF: Ushering In a New Era in High Energy Density Science

Description: This paper describes the status of the stadium-sized National Ignition Facility (NIF), the world's largest laser system and first operational multi-megajoule laser. The 192-beam NIF, located at Lawrence Livermore National Laboratory (LLNL), is 96% complete and scheduled for completion in March 2009. The NIF laser will produce nanosecond laser pulses with energies up to approximately 4 MJ in the infrared (laser wavelength = 1.053-{micro}m) and 2MJ in the ultraviolet (laser wavelength = 0.35-{mic… more
Date: April 30, 2008
Creator: Keane, C & Moses, E I
Partner: UNT Libraries Government Documents Department
open access

Electron cooling rates characterization at Fermilab's Recycler

Description: A 0.1 A, 4.3 MeV DC electron beam is routinely used to cool 8 GeV antiprotons in Fermilab's Recycler storage ring [1]. The primary function of the electron cooler is to increase the longitudinal phase-space density of the antiprotons for storing and preparing high-density bunches for injection into the Tevatron. The longitudinal cooling rate is found to significantly depend on the transverse emittance of the antiproton beam. The paper presents the measured rates and compares them with calculati… more
Date: June 1, 2007
Creator: Prost, Lionel R. & Shemyakin, A.
Partner: UNT Libraries Government Documents Department
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