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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

New experimental capabilities and theoretical insights of high pressure compression waves

Description: Currently there are three platforms that offer quasi-isentropic compression or ramp-wave compression (RWC): light-gas gun, magnetic flux (Z-pinch), and laser. We focus here on the light-gas gun technique and on some current theoretical insights from experimental data. A gradient impedance through the length of the impactor provides the pressure pulse upon impactor to the subject material. Applications and results are given concerning high-pressure strength and liquid to solid, phase transition … more
Date: July 20, 2007
Creator: Orlikowski, D.; Nguyen, J.; Patterson, J. R.; Minich, R.; Martin, L. P. & Holmes, N.
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

Radio-loud high-redshift protogalaxy canidates in Bootes

Description: We used the Near Infrared Camera (NIRC) on Keck I to obtain K{sub s}-band images of four candidate high-redshift radio galaxies selected using optical and radio data in the NOAO Deep Wide-Field Survey in Bootes. Our targets have 1.4 GHz radio flux densities greater than 1 mJy, but are undetected in the optical. Spectral energy distribution fitting suggests that three of these objects are at z > 3, with radio luminosities near the FR-I/FR-II break. The other has photometric redshift z{sub pho… more
Date: July 20, 2007
Creator: Croft, S.; van Breugel, W.; Brown, M. J.; de Vries, W.; Dey, A.; Eisenhardt, P. et al.
Partner: UNT Libraries Government Documents Department
open access

Using RPS Policies to Grow the Solar Market in the United States

Description: The market for photovoltaics in the United States remains small relative to the nation's solar resource potential. Nonetheless, annual grid-connected PV installations have grown from just 4 MW in 2000 to over 100 MW in 2006, fast enough to the catch the attention of the global solar industry. The state of California deserves much of the credit for this growth. The State's historical rebate programs resulted in roughly 75% of the nation's grid-connected PV additions from 2000 through 2006 being … more
Date: November 20, 2007
Creator: Wiser, Ryan H & Wiser, Ryan H.
Partner: UNT Libraries Government Documents Department
open access

Optimal flux patterns in cellular metabolic networks

Description: The availability of whole-cell level metabolic networks of high quality has made it possible to develop a predictive understanding of bacterial metabolism. Using the optimization framework of flux balance analysis, I investigate metabolic response and activity patterns to variations in the availability of nutrient and chemical factors such as oxygen and ammonia by simulating 30,000 random cellular environments. The distribution of reaction fluxes is heavy-tailed for the bacteria H. pylori and E… more
Date: January 20, 2007
Creator: Almaas, E
Partner: UNT Libraries Government Documents Department
open access

GeV electron beams from cm-scale channel guided laser wakefieldaccelerator

Description: Laser-wakefield accelerators (LWFA) can produce electricfields of order 10-100 GV/m suitable for acceleration of electrons torelativistic energies. The wakefields are excited by a relativisticallyintense laser pulse propagating through a plasma and have a phasevelocity determined by the group velocity of the light pulse. Twoimportant effects that can limit the acceleration distanceand hence thenet energy gain obtained by an electron are diffraction of the drivelaser pulse and particle-wake deph… more
Date: February 20, 2007
Creator: Nakamura, K.; Nagler, B.; Toth, Cs.; Geddes, C. G. R.; Schroeder, C.; Esarey, E. et al.
Partner: UNT Libraries Government Documents Department
open access

Testing Short Samples of ITER Conductors and Projection of Their Performance in ITER Magnets

Description: Qualification of the ITER conductor is absolutely necessary. Testing large scale conductors is expensive and time consuming. To test straight 3-4m long samples in a bore of a split solenoid is a relatively economical way in comparison with fabrication of a coil to be tested in a bore of a background field solenoid. However, testing short sample may give ambiguous results due to different constraints in current redistribution in the cable or other end effects which are not present in the large m… more
Date: August 20, 2007
Creator: Martovetsky, N. N.
Partner: UNT Libraries Government Documents Department
open access

Progress on the Design and Fabircation of the MICE SpectrometerSolenoids

Description: The Muon Ionization Cooling Experiment (MICE) willdemonstrate ionization cooling in a short section of a realistic coolingchannel using a muon beam at Rutherford Appleton Laboratory (RAL) in theUK. A five-coil, superconducting spectrometer solenoid magnet at each endof the cooling channel will provide a 4 T uniform field region for thescintillating fiber tracker within the magnet bore tubes. The trackermodules are used to measure the muon beam emittance as it enters andexits the cooling channel… more
Date: June 20, 2007
Creator: Virostek, S.P.; Green, M.A.; Lia, D. & Sizman, M.S.
Partner: UNT Libraries Government Documents Department
open access

An Overview of the Motional Stark Effect Diagnostic On DIII-D And Design Work For An ITER MSE

Description: The advanced tokamak research program at DIII-D relies critically on the measurement of the current density profile. This was made possible by the development of a Motional Stark Effect (MSE) polarimeter that was first installed in 1992. Three major upgrades have since occurred, and improvements in our understanding of critical performance issues and calibration techniques are ongoing. In parallel with these improvements, we have drawn on our DIII-D experience to begin studies and design work f… more
Date: September 20, 2007
Creator: Holcomb, C. T.; Allen, S. L.; Makowski, M. A.; Jayakumar, R. J.; Gu, M. F.; Lerner, S. et al.
Partner: UNT Libraries Government Documents Department
open access

The Energy Diameter Effect

Description: Various relations for the detonation energy and velocity as they relate to the inverse radius of the cylinder are explored. The detonation rate-inverse slope relation seen in reactive flow models can be used to derive the familiar Eyring equation. Generalized inverse radii can be shown to fit large quantities of cylinder and sphere results. A rough relation between detonation energy and detonation velocity is found from collected JWL values. Cylinder test data for ammonium nitrate mixes down to… more
Date: April 20, 2007
Creator: Souers, P; Vitello, P; Garza, R & Hernandez, A
Partner: UNT Libraries Government Documents Department
open access

Detailed chemical kinetic oxidation mechanism for a biodiesel surrogate

Description: A detailed chemical kinetic mechanism has been developed and used to study the oxidation of methyl decanoate, a surrogate for biodiesel fuels. This model has been built by following the rules established by Curran et al. for the oxidation of n-heptane and it includes all the reactions known to be pertinent to both low and high temperatures. Computed results have been compared with methyl decanoate experiments in an engine and oxidation of rapeseed oil methyl esters in a jet stirred reactor. An … more
Date: September 20, 2007
Creator: Herbinet, O; Pitz, W J & Westbrook, C K
Partner: UNT Libraries Government Documents Department
open access

Anti-Hyperon polarization in high energy pp collisions withpolarized beams

Description: We study the longitudinal polarization of the {bar {Sigma}}{sup -}, {bar {Sigma}}{sup +}, {bar {Xi}}{sup 0} and {bar {Xi}}{sup +} anti-hyperons in polarized high energy pp collisions at large transverse momenta, extending a recent study for the {bar {Lambda}} antihyperon. We make predictions by using different parameterizations of the polarized parton densities and models for the polarized fragmentation functions. Similar to the {bar {Lambda}} polarization, the {bar {Xi}}{sup 0} and {bar {Xi}}{… more
Date: November 20, 2007
Creator: Chen, Ye; Liang, Zuo-tang; Sichtermann, Ernst; Xu, Qing-hua & Zhou, Shan-shan
Partner: UNT Libraries Government Documents Department
open access

Gamma-Ray Compton Light Source Development at LLNL

Description: No Description Available.
Date: June 20, 2007
Creator: Hartemann, F. V.; Anderson, S. G.; Barty, C. J.; Gibson, D. J.; Hagmann, C. A.; Johnson, M. S. et al.
Partner: UNT Libraries Government Documents Department
open access

Bounds on Unparticles from the Higgs Sector

Description: We study supersymmetric QCD in the conformal window as a laboratory for unparticle physics, and analyze couplings between the unparticle sector and the Higgs sector. These couplings can lead to the unparticle sector being pushed away from its scale invariant fixed point. We show that this implies that low energy experiments will not be able to see unparticle physics, and the best hope of seeing unparticles is in high energy collider experiments such as the Tevatron and the LHC. We also demonstr… more
Date: May 20, 2007
Creator: Fox, Patrick J.; Rajaraman, Arvind & Shirman, Yuri
Partner: UNT Libraries Government Documents Department
open access

M-theory through the looking glass: Tachyon condensation in the E8 heterotic string

Description: We study the spacetime decay to nothing in string theory and M-theory. First we recall a nonsupersymmetric version of heterotic M-theory, in which bubbles of nothing -- connecting the two E_8 boundaries by a throat -- are expected to be nucleated. We argue that the fate of this system should be addressed at weak string coupling, where the nonperturbative instanton instability is expected to turn into a perturbative tachyonic one. We identify the unique string theory that could describe this pro… more
Date: September 20, 2007
Creator: Horava, Petr; Horava, Petr & Keeler, Cynthia A.
Partner: UNT Libraries Government Documents Department
open access

POLYCHLORINATED BIPHENYL COMPLIANCE ISSUES IN THE 21ST CENTURY: POORLY RECOGNIZED AND POTENTIALLY DEVASTATING-8162

Description: Thirty-one years have passed since the United States Congress passed the Toxic Substances Control Act (TSCA) [1]. The 1976 law essentially eliminated future production of polychlorinated biphenyls (PCBs) within the United States and greatly limited the use of previously manufactured PCBs and PCB products. The ultimate objective of the law was the complete elimination of these chemicals due to concerns about their potentially toxic effects on health and the environment. PCBs were manufactured in… more
Date: November 20, 2007
Creator: Lowry, N
Partner: UNT Libraries Government Documents Department
open access

Fast ignition relevant study of the flux of high intensity laser-generated electrons via a hollow cone into a laser-imploded plasma

Description: An integrated experiment relevant to fast ignition. A Cu-doped deuterated polymer spherical shell target with an inserted hollow Au cone is imploded by a six-beam 900-J, 1-ns laser. A 10-ps, 70-J laser pulse is focused into the cone at the time of peak compression. The flux of high-energy electrons through the imploded material is determined from the yield of Cu K{sub {alpha}} fluorescence by comparison with a Monte Carlo model. The electrons are estimated to carry about 15% of the laser energy… more
Date: November 20, 2007
Creator: Key, M
Partner: UNT Libraries Government Documents Department
open access

CORBA-Based Distributed Software Framework for the NIF Integrated Computer Control System

Description: The National Ignition Facility (NIF), currently under construction at the Lawrence Livermore National Laboratory, is a stadium-sized facility containing a 192-beam, 1.8 Megajoule, 500-Terawatt, ultra-violet laser system together with a 10-meter diameter target chamber with room for nearly 100 experimental diagnostics. The NIF is operated by the Integrated Computer Control System (ICCS) which is a scalable, framework-based control system distributed over 800 computers throughout the NIF. The fra… more
Date: November 20, 2007
Creator: Stout, E A; Carey, R W; Estes, C M; Fisher, J M; Lagin, L J; Mathisen, D G et al.
Partner: UNT Libraries Government Documents Department
open access

Boltzmann babies in the proper time measure

Description: After commenting briefly on the role of the typicality assumption in science, we advocate a phenomenological approach to the cosmological measure problem. Like any other theory, a measure should be simple, general, well defined, and consistent with observation. This allows us to proceed by elimination. As an example, we consider the proper time cutoff on a geodesic congruence. It predicts that typical observers are quantum fluctuations in the early universe, or Boltzmann babies. We sharpen this… more
Date: December 20, 2007
Creator: Bousso, Raphael; Bousso, Raphael; Freivogel, Ben & Yang, I-Sheng
Partner: UNT Libraries Government Documents Department
open access

Progress on the Design of the Coupling coils for MICE andMUCOOL

Description: The Muon Ionization Cooling Experiment (MICE) [1]willdemonstrate ionization cooling in a short section of a realistic coolingchannel using a muon beam at Rutherford Appleton Laboratory (RAL) in theUK. The MICE RF and Coupling Coil (RFCC) Module consists of asuperconducting solenoid mounted around four normal conducting 201.25-MHzRF cavities. The coil package that surrounds the RF cavities is to bemounted in a 1.4 m diameter vacuum vessel. The coupling coil confines thebeam in the RFCC module wi… more
Date: June 20, 2007
Creator: Green, M. A.; Li, D.; Virostek, Steve P.; Wang, L.; Wu, H.; Li, L. K. et al.
Partner: UNT Libraries Government Documents Department
open access

Azimuthal Asymmetric Distribution of Hadrons Inside a Jet atHadron Collider

Description: We study the azimuthal asymmetric distribution of hadronsinside a high energy jet in the single transverse polarized proton protonscattering, coming from the Collins effect multiplied by the quarktransversity distribution. We argue that the Collins function in thisprocess is the same as that in the semi-inclusive deep inelasticscattering. The experimental study of this process will provide usimportant information on the quark transversity distribution and test theuniversality of the fragmentati… more
Date: September 20, 2007
Creator: Yuan, Feng
Partner: UNT Libraries Government Documents Department
open access

Simulating Electron Effects in Heavy-Ion Accelerators with Solenoid Focusing

Description: Contamination from electrons is a concern for solenoid-focused ion accelerators being developed for experiments in high-energy-density physics. These electrons, produced directly by beam ions hitting lattice elements or indirectly by ionization of desorbed neutral gas, can potentially alter the beam dynamics, leading to a time-varying focal spot, increased emittance, halo, and possibly electron-ion instabilities. The electrostatic particle-in-cell code WARP is used to simulate electron-cloud st… more
Date: June 20, 2007
Creator: Sharp, W. M.; Grote, D. P.; Cohen, R. H.; Friedman, A.; Molvik, A. W.; Vay, J. L. et al.
Partner: UNT Libraries Government Documents Department
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