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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
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

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

Control of the Magnetic and Magnetotransport Properties of La0.67Sr0.33MnO3 Thin Films Through Epitaxial Strain

Description: The influence of epitaxial strain, in the form of tetragonal distortions, on the magnetic and magnetotransport properties of La{sub 0.67}Sr{sub 0.33}MnO{sub 3} thin films was studied. The tetragonal distortion (c/a ratio) was modulated through the choice of the substrate, ranging from c/a=1.007 on (001)-oriented (LaAlO{sub 3}){sub 0.3}(Sr{sub 2}AlTaO{sub 6}){sub 0.7} substrates to 0.952 on (110)-oriented GdScO{sub 3} substrates. In agreement with previous theoretical predictions, these large va… more
Date: December 20, 2007
Creator: Arenholz, Elke; Takamura, Y.; Chopdekar, R.V.; Arenholz, E. & Suzuki, Y.
Partner: UNT Libraries Government Documents Department
open access

Exp6-polar thermodynamics of dense supercritical water

Description: We introduce a simple polar fluid model for the thermodynamics of dense supercritical water based on a Buckingham (exp-6) core and point dipole representation of the water molecule. The proposed exp6-polar thermodynamics, based on ideas originally applied to dipolar hard spheres, performs very well when tested against molecular dynamics simulations. Comparisons of the model predictions with experimental data available for supercritical water yield excellent agreement for the shock Hugoniot, iso… more
Date: December 13, 2007
Creator: Bastea, S & Fried, L E
Partner: UNT Libraries Government Documents Department
open access

Transplanting native dominant plants to facilitate community development in restored coastal plain wetlands.

Description: Abstract: Drained depressional wetlands are typically restored by plugging ditches or breaking drainage tiles to allow recovery of natural ponding regimes, while relying on passive recolonization from seed banks and dispersal to establish emergent vegetation. However, in restored depressions of the southeastern United States Coastal Plain, certain characteristic rhizomatous graminoid species may not recolonize because they are dispersal-limited and uncommon or absent in the seed banks of distur… more
Date: December 1, 2007
Creator: De Steven, Diane & Sharitz, Rebecca R.
Partner: UNT Libraries Government Documents Department
open access

In situ x-ray photoelectron spectroscopy studies of gas/solidinterfaces at near-ambient conditions

Description: X-ray photoelectron spectroscopy (XPS) is a quantitative, chemically specific technique with a probing depth of a few angstroms to a few nanometers. It is therefore ideally suited to investigate the chemical nature of the surfaces of catalysts. Because of the scattering of electrons by gas molecules, XPS is generally performed under vacuum conditions. However, for thermodynamic and/or kinetic reasons, the catalyst's chemical state observed under vacuum reaction conditions is not necessarily the… more
Date: December 3, 2007
Creator: Bluhm, Hendrik; Havecker, Michael; Knop-Gericke, Axel; Kiskinova,Maya; Schlogl, Robert & Salmeron, Miquel
Partner: UNT Libraries Government Documents Department
open access

Shape Determination for Deformed Electromagnetic Cavities

Description: The measured physical parameters of a superconducting cavity differ from those of the designed ideal cavity. This is due to shape deviations caused by both loose machine tolerances during fabrication and by the tuning process for the accelerating mode. We present a shape determination algorithm to solve for the unknown deviations from the ideal cavity using experimentally measured cavity data. The objective is to match the results of the deformed cavity model to experimental data through least-… more
Date: December 10, 2007
Creator: Akcelik, Volkan; Ko, Kwok; Lee, Lie-Quan; Li, Zhenghai; Ng, Cho-Kuen & Xiao, Liling
Partner: UNT Libraries Government Documents Department
open access

Some Interesting Min-Bias Distributions for Early LHC Runs

Description: A few observable distributions in min-bias (inelastic, non-diffractive) events which could be well constrained with early LHC data are presented, with some comments on their significance for placing constraints on theoretical models. The effects of fiducial cuts (p{perpendicular} > 0.5 GeV, |{eta}| < 2.5) and extrapolation from the Tevatron are illustrated.
Date: December 1, 2007
Creator: Skands, P. Z.
Partner: UNT Libraries Government Documents Department
open access

Plasma Suppression of Large Scale Structure Formation in the Universe

Description: We point out that during the reionization epoch of the cosmic history, the plasma collective effect among the ordinary matter would suppress the large scale structure formation. The imperfect Debye shielding at finite temperature would induce a residual long-range electrostatic potential which, working together with the baryon thermal pressure, would counter the gravitational collapse. As a result the effective Jean's length, {tilde {lambda}}{sub J}, is increased by a factor, {tilde {lambda}}{s… more
Date: December 10, 2007
Creator: Chen, Pisin & Lai, Kwang-Chang
Partner: UNT Libraries Government Documents Department
open access

SOFC Interconnect Work at NETL

Description: No Description Available.
Date: December 1, 2007
Creator: Jablonski, P. D. & Alman, D. E.
Partner: UNT Libraries Government Documents Department
open access

Observation of the Decay B+-(c) ---> J/psi pi+- and Measurement of the B+-(c) Mass

Description: The B{sub c}{sup {+-}} meson is observed through the decay B{sub c}{sup {+-}} {yields} J/{psi} {pi}{sup {+-}}, in data corresponding to an integrated luminosity of 2.4 fb{sup -1} recorded by the CDF II detector at the Fermilab Tevatron. A signal of 108 {+-} 15 candidates is observed, with a significance that exceeds 8{sigma}. The mass of the B{sub c}{sup {+-}} meson is measured to be 6275.6 {+-} 2.9(stat.) {+-} 2.5(syst.) MeV/c{sup 2}.
Date: December 1, 2007
Creator: Aaltonen, T.
Partner: UNT Libraries Government Documents Department
open access

Status of FNAL SciBooNE experiment

Description: SciBooNE is a new experiment at FNAL which will make precision neutrino-nucleus cross section measurements in the one GeV region. These measurements are essential for the future neutrino oscillation experiments. We started data taking in the antineutrino mode on June 8, 2007, and collected 5.19 x 10{sup 19} protons on target (POT) before the accelerator shutdown in August. The first data from SciBooNE are reported in this article.
Date: December 1, 2007
Creator: Nakajima, Yasuhiro & U., /Kyoto
Partner: UNT Libraries Government Documents Department
open access

Large-Scale Transport Model Uncertainty and Sensitivity Analysis: Distributed Sources in Complex Hydrogeologic Systems

Description: The Underground Test Area (UGTA) Project of the U.S. Department of Energy, National Nuclear Security Administration Nevada Site Office is in the process of assessing and developing regulatory decision options based on modeling predictions of contaminant transport from underground testing of nuclear weapons at the Nevada Test Site (NTS). The UGTA Project is attempting to develop an effective modeling strategy that addresses and quantifies multiple components of uncertainty including natural vari… more
Date: December 1, 2007
Creator: Sig Drellack, Lance Prothro
Partner: UNT Libraries Government Documents Department
open access

Measurement of the B to Xs gammaBranching Fraction and Photon Energy Spectrum usingthe Recoil Method

Description: We present a measurement of the branching fraction and photon energy spectrum for the decay B {yields} X{sub s}{gamma} using data from the BABAR experiment. The data sample corresponds to an integrated luminosity of 210 fb{sup -1}, from which approximately 680,000 B{bar B} events are tagged by a fully reconstructed hadronic decay of one of the B mesons. In the decay of the second B meson, an isolated high-energy photon is identified. We measure {Beta}(B {yields} X{sub s}{gamma}) = (3.66 {+-} 0.… more
Date: December 4, 2007
Creator: Aubert, B.
Partner: UNT Libraries Government Documents Department
open access

Soft Error Vulnerability of Iterative Linear Algebra Methods

Description: Devices become increasingly vulnerable to soft errors as their feature sizes shrink. Previously, soft errors primarily caused problems for space and high-atmospheric computing applications. Modern architectures now use features so small at sufficiently low voltages that soft errors are becoming significant even at terrestrial altitudes. The soft error vulnerability of iterative linear algebra methods, which many scientific applications use, is a critical aspect of the overall application vulner… more
Date: December 15, 2007
Creator: Bronevetsky, G & de Supinski, B
Partner: UNT Libraries Government Documents Department
open access

The Milky Way as a Kiloparsec-Scale Axionscope

Description: Very high energy gamma-rays are expected to be absorbed by the extragalactic background light over cosmological distances via the process of electron-positron pair production. Recent observations of cosmologically distant gamma-ray emitters by ground based gamma-ray telescopes have, however, revealed a surprising degree of transparency of the universe to very high energy photons. One possible mechanism to explain this observation is the oscillation between photons and axion-like-particles (ALPs… more
Date: December 1, 2007
Creator: Simet, Melanie; Hooper, Dan & Serpico, Pasquale D.
Partner: UNT Libraries Government Documents Department
open access

Carbonyl Emissions from Gasoline and Diesel Motor Vehicles

Description: Carbonyls from gasoline powered light-duty vehicles (LDVs) and heavy-duty diesel powered vehicles (HDDVs) operated on chassis dynamometers were measured using an annular denuder-quartz filter-polyurethane foam sampler with O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine derivatization and chromatography-mass spectrometry analyses. Two internal standards were utilized based on carbonyl recovery, 4-fluorobenzaldehyde for<C8 carbonyls and 6-fluoro-4-chromanone for>_C8 compounds. Gas- and partic… more
Date: December 1, 2007
Creator: Destaillats, Hugo; Jakober, Chris A.; Robert, Michael A.; Riddle, Sarah G.; Destaillats, Hugo; Charles, M. Judith et al.
Partner: UNT Libraries Government Documents Department
open access

Enhancing Price Response Programs through Auto-DR: California's 2007 Implementation Experience

Description: This paper describes automated demand response (Auto-DR) activities, an innovative effort in California to ensure that DR programs produce effective and sustainable impacts. Through the application of automation and communication technologies coupled with well-designed incentives and DR programs such as Critical Peak Pricing (CPP) and Demand Bidding (DBP), Auto-DR is opening up the opportunity for many different types of buildings to effectively participate in DR programs. We present the result… more
Date: December 18, 2007
Creator: Kiliccote, Sila; Wikler, Greg; Chiu, Albert; Piette, Mary Ann; Kiliccote, Sila; Hennage, Dan et al.
Partner: UNT Libraries Government Documents Department
open access

Electron Beam Lifetime in SPEAR3: Measurement and Simulation

Description: In this paper we report on electron beam lifetime measurements as a function of scraper position, RF voltage and bunch fill pattern in SPEAR3. We then outline development of an empirical, macroscopic model using the beam-loss rate equation. By identifying the dependence of loss coefficients on accelerator and beam parameters, a numerically-integrating simulator can be constructed to compute beam decay with time. In a companion paper, the simulator is used to train a parametric, non-linear dynam… more
Date: December 19, 2007
Creator: Corbett, J.; Huang, X.; Lee, M. & Lui, P.
Partner: UNT Libraries Government Documents Department
open access

ILC Reference Design Report: Accelerator Executive Summary

Description: The International Linear Collider (ILC) is a 200-500 GeV center-of-mass high-luminosity linear electron-positron collider, based on 1.3 GHz superconducting radiofrequency (SCRF) accelerating cavities. The use of the SCRF technology was recommended by the International Technology Recommendation Panel (ITRP) in August 2004 [1], and shortly thereafter endorsed by the International Committee for Future Accelerators (ICFA). In an unprecedented milestone in high-energy physics, the many institutes ar… more
Date: December 14, 2007
Creator: Phinney, Nan
Partner: UNT Libraries Government Documents Department
open access

Charm Spectroscopy at BaBar

Description: We present a mini-review on charm spectroscopy at the BABAR experiment. We first report on the c{bar s} meson spectrum, and present precise measurements of the D{sub s1}(2536) meson as well as the properties of the many new states discovered since 2003 (D*{sub s0}(2317), D{sub s1}(2460), D*{sub sJ}(2860), and D{sub sJ}(2700) mesons). We then discuss about charmed baryons observed recently in the BABAR experiment: {Omega}{sub c}{sup 0} and {Omega}*{sub c}{sup 0} css baryons, {Lambda}{sub c}(2940… more
Date: December 21, 2007
Creator: Poireau, Vincent
Partner: UNT Libraries Government Documents Department
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