1,271 Matching Results

Results open in a new window/tab.

3-Nitropropionic Acid is a Suicide Inhibitor of MitochondrialRespiration that, Upon Oxidation by Complex II, Forms a Covalent AdductWith a Catalytic Base Arginine in the Active Site of the Enzyme (open access)

3-Nitropropionic Acid is a Suicide Inhibitor of MitochondrialRespiration that, Upon Oxidation by Complex II, Forms a Covalent AdductWith a Catalytic Base Arginine in the Active Site of the Enzyme

We report three new structures of mitochondrial respiratory Complex II (succinate ubiquinone oxidoreductase, E.C. 1.3.5.1) at up to 2.1 {angstrom} resolution, with various inhibitors. The structures define the conformation of the bound inhibitors and suggest the residues involved in substrate binding and catalysis at the dicarboxylate site. In particular they support the role of Arg297 as a general base catalyst accepting a proton in the dehydrogenation of succinate. The dicarboxylate ligand in oxaloacetate-containing crystals appears to be the same as that reported for Shewanella flavocytochrome c treated with fumarate. The plant and fungal toxin 3-nitropropionic acid, an irreversible inactivator of succinate dehydrogenase, forms a covalent adduct with the side chain of Arg297. The modification eliminates a trypsin cleavage site in the flavoprotein, and tandem mass spectroscopic analysis of the new fragment shows the mass of Arg 297 to be increased by 83 Da and to have potential of losing 44 Da, consistent with decarboxylation, during fragmentation.
Date: December 1, 2005
Creator: Huang, Li-shar; Sun, Gang; Cobessi, David; Wang, Andy C.; Shen,John T.; Tung, Eric Y. et al.
System: The UNT Digital Library
Ambrosia Beetle (Coleoptera: Scolytidae) Species, Flight, and Attack on Living Eastern Cottonwood Trees. (open access)

Ambrosia Beetle (Coleoptera: Scolytidae) Species, Flight, and Attack on Living Eastern Cottonwood Trees.

ABSTRACT In spring 2002, ambrosia beetles (Coleoptera: Scolytidae) infested an intensively managed 22-ha tree plantation on the upper coastal plain of South Carolina. Nearly 3,500 scolytids representing 28 species were captured in ethanol-baited traps from 18 June 2002 to 18 April 2004. More than 88% of total captures were exotic species. Five species [Dryoxylon onoharaensum (Murayama), Euwallacea validus (Eichhoff), Pseudopityophthorus minutissimus (Zimmermann), Xyleborus atratus Eichhoff, and Xyleborus impressus Eichhoff]) were collected in South Carolina for the Þrst time. Of four tree species in the plantation, eastern cottonwood, Populus deltoides Bartram, was the only one attacked, with nearly 40% of the trees sustaining ambrosia beetle damage. Clone ST66 sustained more damage than clone S7C15. ST66 trees receiving fertilization were attacked more frequently than trees receiving irrigation, irrigation_fertilization, or controls, although the number of S7C15 trees attacked did not differ among treatments. The study location is near major shipping ports; our results demonstrate the necessity for intensive monitoring programs to determine the arrival, spread, ecology, and impact of exotic scolytids.
Date: December 1, 2005
Creator: Coyle, D.R. & Wallace, D.C. Booth: M.S.
System: The UNT Digital Library
Antiproton cooling in the Fermilab Recycler Ring (open access)

Antiproton cooling in the Fermilab Recycler Ring

The 8.9-GeV/c Recycler antiproton storage ring is equipped with both stochastic and electron cooling systems. These cooling systems are designed to assist accumulation of antiprotons for the Tevatron collider operations. In this paper we report on an experimental demonstration of electron cooling of high-energy antiprotons. At the time of writing this report, the Recycler electron cooling system is routinely used in collider operations. It has helped to set recent peak luminosity records.
Date: December 1, 2005
Creator: Nagaitsev, S.; Bolshakov, A.; Broemmelsiek, D.; Burov, Alexey V.; Carlson, K.; Gattuso, C. et al.
System: The UNT Digital Library
Assessment of Unglazed Solar Domestic Water Heaters (open access)

Assessment of Unglazed Solar Domestic Water Heaters

Conference paper investigating cost-performance tradeoffs in replacing glazed collectors with unglazed collectors in solar domestic water heating systems.
Date: December 1, 2005
Creator: Burch, J.; Salasovich, J. & Hillman, T.
System: The UNT Digital Library
B -> d* l nu and b -> d l nu form-factors in staggered chiral perturbation theory (open access)

B -> d* l nu and b -> d l nu form-factors in staggered chiral perturbation theory

We calculate the B {yields} D and B {yields} D* form factors at zero recoil in Staggered Chiral Perturbation Theory. We consider heavy-light mesons in which only the light (u, d, or s) quark is staggered; current lattice simulations generally use a highly improved action such as the Fermilab or NRQCD action for the heavy (b or c) quark. We work to lowest order in the heavy quark expansion and to next-to-leading order in the chiral expansion. We present results for a partially quenched theory with three sea quarks in which there are no mass degeneracies (the ''1+1+1'' theory) and for a partially quenched theory in which the u and d sea quark masses are equal (the ''2+1'' theory). We also present results for full (2+1) QCD, along with a numerical estimate of the size of staggered discretization errors. Finally, we calculate the finite volume corrections to the form factors and estimate their numerical size in current lattice simulations.
Date: December 1, 2005
Creator: Laiho, Jack & Van de Water, Ruth S.
System: The UNT Digital Library
Benchmarking and Self-Assessment in the Wine Industry (open access)

Benchmarking and Self-Assessment in the Wine Industry

Not all industrial facilities have the staff or theopportunity to perform a detailed audit of their operations. The lack ofknowledge of energy efficiency opportunities provides an importantbarrier to improving efficiency. Benchmarking programs in the U.S. andabroad have shown to improve knowledge of the energy performance ofindustrial facilities and buildings and to fuel energy managementpractices. Benchmarking provides a fair way to compare the energyintensity of plants, while accounting for structural differences (e.g.,the mix of products produced, climate conditions) between differentfacilities. In California, the winemaking industry is not only one of theeconomic pillars of the economy; it is also a large energy consumer, witha considerable potential for energy-efficiency improvement. LawrenceBerkeley National Laboratory and Fetzer Vineyards developed the firstbenchmarking tool for the California wine industry called "BEST(Benchmarking and Energy and water Savings Tool) Winery". BEST Wineryenables a winery to compare its energy efficiency to a best practicereference winery. Besides overall performance, the tool enables the userto evaluate the impact of implementing efficiency measures. The toolfacilitates strategic planning of efficiency measures, based on theestimated impact of the measures, their costs and savings. The tool willraise awareness of current energy intensities and offer an efficient wayto evaluate the impact of future efficiency measures.
Date: December 1, 2005
Creator: Galitsky, Christina; Radspieler, Anthony; Worrell, Ernst; Healy,Patrick & Zechiel, Susanne
System: The UNT Digital Library
Boiling Temperature and Reversed Deliquescence Relative Humidity Measurements for Mineral Assemblages in the NaCl + NaNO3 + KNO3 + Ca(NO3)2 + H2O System (open access)

Boiling Temperature and Reversed Deliquescence Relative Humidity Measurements for Mineral Assemblages in the NaCl + NaNO3 + KNO3 + Ca(NO3)2 + H2O System

Boiling temperature measurements have been made at ambient pressure for saturated ternary solutions of NaCl + KNO{sub 3} + H{sub 2}O, NaNO{sub 3} + KNO{sub 3} + H{sub 2}O, and NaCl + Ca(NO{sub 3}){sub 2} + H{sub 2}O over the full composition range, along with those of the single salt systems. Boiling temperatures were also measured for the four component NaCl + NaNO{sub 3} + KNO{sub 3} + H{sub 2}O and five component NaCl + NaNO{sub 3} + KNO{sub 3} + Ca(NO{sub 3}){sub 2} + H{sub 2}O mixtures, where the solute mole fraction of Ca(NO{sub 3}){sub 2}, x(Ca(NO{sub 3}){sub 2}), was varied between 0 and 0.25. The maximum boiling temperature found for the NaCl + KNO{sub 3} + H{sub 2}O system is {approx} 134.9 C; for the NaNO{sub 3} + KNO{sub 3} + H{sub 2}O system is {approx} 165.1 C at x(NaNO{sub 3}) {approx} 0.46 and x(KNO{sub 3}) {approx} 0.54; and for the NaCl + Ca(NO{sub 3}){sub 2} + H{sub 2}O system is 164.7 {+-} 0.6 C at x(NaCl) {approx} 0.25 and x(Ca(NO{sub 3}){sub 2}) {approx} 0.75. The NaCl + NaNO{sub 3} + KNO{sub 3} + Ca(NO{sub 3}){sub 2} + H{sub 2}O system forms molten salts below their maximum boiling …
Date: December 1, 2005
Creator: Rard, J A; Staggs, K J; Day, S D & Carroll, S A
System: The UNT Digital Library
CDF computing and event data models (open access)

CDF computing and event data models

The authors discuss the computing systems, usage patterns and event data models used to analyze Run II data from the CDF-II experiment at the Tevatron collider. A critical analysis of the current implementation and design reveals some of the stronger and weaker elements of the system, which serve as lessons for future experiments. They highlight a need to maintain simplicity for users in the face of an increasingly complex computing environment.
Date: December 1, 2005
Creator: Snider, F.D.
System: The UNT Digital Library
Characterization and Properties of Metallic Iron and Iron-Oxide Nanoparticles: Spectroscopy, Electrochemistry, and Kinetics (open access)

Characterization and Properties of Metallic Iron and Iron-Oxide Nanoparticles: Spectroscopy, Electrochemistry, and Kinetics

There are reports that nano-sized zero-valent iron (Fe0) exhibits greater reactivity than micro-sized particles of Fe0, and it has been suggested that the higher reactivity of nano-Fe0 may impart advantages for groundwater remediation or other environmental applications. However, most of these reports are preliminary in that they leave a host of potentially significant (and often challenging) material or process variables either uncontrolled or unresolved. In an effort to better understand the reactivity of nano-Fe0, we have used a variety of complementary techniques to characterize two widely studied nano-Fe0 preparations:  one synthesized by reduction of goethite with heat and H2 (FeH2) and the other by reductive precipitation with borohydride (FeBH). FeH2 is a two-phase material consisting of 40 nm α-Fe0 (made up of crystals approximately the size of the particles) and Fe3O4 particles of similar size or larger containing reduced sulfur; whereas FeBH is mostly 20−80 nm metallic Fe particles (aggregates of <1.5 nm grains) with an oxide shell/coating that is high in oxidized boron. The FeBH particles further aggregate into chains. Both materials exhibit corrosion potentials that are more negative than nano-sized Fe2O3, Fe3O4, micro-sized Fe0, or a solid Fe0 disk, which is consistent with their rapid reduction of oxygen, …
Date: December 1, 2005
Creator: Nurmi, J. T.; Tratnyek, Paul G.; Sarathy, V.; Baer, D. R.; Amonette, J. E.; Pecher, K. et al.
System: The UNT Digital Library
Close Sequence Comparisons are Sufficient to Identify Humancis-Regulatory Elements (open access)

Close Sequence Comparisons are Sufficient to Identify Humancis-Regulatory Elements

Cross-species DNA sequence comparison is the primary method used to identify functional noncoding elements in human and other large genomes. However, little is known about the relative merits of evolutionarily close and distant sequence comparisons, due to the lack of a universal metric for sequence conservation, and also the paucity of empirically defined benchmark sets of cis-regulatory elements. To address this problem, we developed a general-purpose algorithm (Gumby) that detects slowly-evolving regions in primate, mammalian and more distant comparisons without requiring adjustment of parameters, and ranks conserved elements by P-value using Karlin-Altschul statistics. We benchmarked Gumby predictions against previously identified cis-regulatory elements at diverse genomic loci, and also tested numerous extremely conserved human-rodent sequences for transcriptional enhancer activity using reporter-gene assays in transgenic mice. Human regulatory elements were identified with acceptable sensitivity and specificity by comparison with 1-5 other eutherian mammals or 6 other simian primates. More distant comparisons (marsupial, avian, amphibian and fish) failed to identify many of the empirically defined functional noncoding elements. We derived an intuitive relationship between ancient and recent noncoding sequence conservation from whole genome comparative analysis, which explains some of these findings. Lastly, we determined that, in addition to strength of conservation, genomic location …
Date: December 1, 2005
Creator: Prabhakar, Shyam; Poulin, Francis; Shoukry, Malak; Afzal, Veena; Rubin, Edward M.; Couronne, Olivier et al.
System: The UNT Digital Library
Cold-Climate Solar Domestic Water Heating Systems: Life-Cycle Analyses and Opportunities for Cost Reduction (open access)

Cold-Climate Solar Domestic Water Heating Systems: Life-Cycle Analyses and Opportunities for Cost Reduction

Conference paper regarding research in potential cost-savings measures for cold-climate solar domestic water hearing systems.
Date: December 1, 2005
Creator: Burch, J.; Salasovich, J. & Hillman, T.
System: The UNT Digital Library
Colour annealing - a toy model of colour reconnections (open access)

Colour annealing - a toy model of colour reconnections

We present a simple toy model for colour reconnections at the nonperturbative level. The model resembles an annealing-type algorithm and is applicable to any collider and process type, though we argue for a possible enhancement of the effect in hadron-hadron collisions. We present a simple application and study of the consequences for semileptonic t{bar t} events at the Tevatron.
Date: December 1, 2005
Creator: Sandhoff, Marisa; U., /Wuppertal; Skands, Peter & /Fermilab
System: The UNT Digital Library
A Comparative Study for Colloidal Quantum Dot Conduction Bandstate Calculations (open access)

A Comparative Study for Colloidal Quantum Dot Conduction Bandstate Calculations

Via the comparison of th results of a few well controlled calculations methods, we analyze the relative importance of bulk band structure, multi-bulk band coupling and boundary conditions in determining the colloidal quantum dot conduction band eigen energies. We find that while the bulk band structure and correct boundary conditions are important, the effects of multi-bulk band coupling is small. We propose that a heterostructure picture where electron envelope functions inside and outside the quantum dot being connected at the boundary can be applied to collodial quantum dots.
Date: December 1, 2005
Creator: Luo, Jun-Wei; Li, Shu-Shen; Xia, Jian-Bai & Wang, Lin-Wang
System: The UNT Digital Library
The Complete Sequence of the Mitochondrial Genome of the Chamberednautilus (Mollusca: Cephalopoda) (open access)

The Complete Sequence of the Mitochondrial Genome of the Chamberednautilus (Mollusca: Cephalopoda)

Background: Mitochondria contain small genomes that arephysically separate from those of nuclei. Their comparison serves as amodel system for understanding the processes of genome evolution.Although complete mitochondrial genome sequences have been reported formore than 600 animals, the taxonomic sampling is highly biased towardvertebrates and arthropods, leaving much of the diversity yetuncharacterized. Results: The mitochondrial genome of a cephalopodmollusk, the Chambered Nautilus, is 16,258 nts in length and 59.5 percentA+T, both values that are typical of animal mitochondrial genomes. Itcontains the 37 genes that are typical for animal mtDNAs, with 15 on oneDNA strand and 22 on the other. The arrangement of these genes can bederived from that of the distantly related Katharina tunicata (Mollusca:Polyplacophora) by a switch in position of two large blocks of genes andtranspositions of four tRNA genes. There is strong skew in thedistribution of nucleotides between the two strands. There are an unusualnumber of non-coding regions and their function, if any, is not known;however, several of these demark abrupt shifts in nucleotide skew,suggesting that they may play roles in transcription and/or replication.One of the non-coding regions contains multiple repeats of a tRNA-likesequence. Some of the tRNA genes appear to overlap on the same strand,but this could be …
Date: December 1, 2005
Creator: Boore, Jeffrey L.
System: The UNT Digital Library
Continuing u.s. participation in the lhc accelerator program (open access)

Continuing u.s. participation in the lhc accelerator program

The U.S. LHC Accelerator Research Program (LARP) was established to enable U.S. accelerator specialists to take on active and important roles in the LHC accelerator project during its commissioning and early operations, and to be a major collaborator in future LHC performance upgrades. It is hoped that this follow-on effort to the U.S. contributions to the LHC accelerator project will improve the capabilities of the U.S. accelerator community in accelerator science and technology in order to more effectively use, develop, and preserve unique U.S. resources and capabilities during the LHC era.
Date: December 1, 2005
Creator: Syphers, M.J.
System: The UNT Digital Library
Controlled Fusion with Hot-ion Mode in a Degenerate Plasma (open access)

Controlled Fusion with Hot-ion Mode in a Degenerate Plasma

n a Fermi-degenerate plasma, the rate of electron physical processes is much reduced from the classical prediction, possibly enabling new regimes for controlled nuclear fusion, including the hot-ion mode, a regime in which the ion temperature exceeds the electron temperature. Previous calculations of these processes in dense plasmas are now corrected for partial degeneracy and relativistic effects, leading to an expanded regime of self-sustained fusion.
Date: December 1, 2005
Creator: Fisch, S. Son and N.J.
System: The UNT Digital Library
Dark matter and gamma-rays from Draco: MAGIC, GLAST and CACTUS (open access)

Dark matter and gamma-rays from Draco: MAGIC, GLAST and CACTUS

The dwarf spheroidal galaxy Draco has long been considered likely to be one of the brightest point sources of gamma-rays generated through dark matter annihilations. Recent studies of this object have found that it remains largely intact from tidal striping, and may be more massive than previously thought. In this article, we revisit Draco as a source of dark matter annihilation radiation, with these new observational constraints in mind. We discuss the prospects for the experiments MAGIC and GLAST to detect dark matter in Draco, as well as constraints from the observations of EGRET. We also discuss the possibility that the CACTUS experiment has already detected gamma-rays from Draco. We find that it is difficult to generate the flux reported by CACTUS without resorting to non-thermally produced WIMPs and/or a density spike in Draco's dark matter distribution due to the presence of an intermediate mass black hole. We also find that for most annihilation modes, a positive detection of Draco by CACTUS would be inconsistent with the lack of events seen by EGRET.
Date: December 1, 2005
Creator: Bergstrom, Lars; U., /Stockholm; Hooper, Dan & /Fermilab
System: The UNT Digital Library
Double Gap Alfvén Eigenmodes: Revisiting Eigenmodes Interaction with the Alfvén Continuum (open access)

Double Gap Alfvén Eigenmodes: Revisiting Eigenmodes Interaction with the Alfvén Continuum

A new type of global shear Alfvén Eigenmode is found in tokamak plasmas where the mode localization is in the region intersecting the Alfvén continuum. The eigenmode is formed by the coupling of two solutions from two adjacent gaps (akin to potential wells) in the shear Alfvén continuum. For tokamak plasmas with reversed magnetic shear it is shown that the toroidiciy-induced solution tunnels through the continuum to match the ellipticity-induced Alfvén eigenmode (TAE and EAE, respectively) so that the resulting solution is continuous at the point of resonance with the continuum. The existence of these Double Gap Alfvén Eigenmodes (DGAEs) allows for potentially new ways of coupling edge fields to the plasma core in conditions where the core region is conventionally considered inaccessible. Implications include new approaches to heating and current drive in fusion plasmas as well as its possible use as core diagnostic in burning plasmas.
Date: December 1, 2005
Creator: Gorelenkov, N. N.
System: The UNT Digital Library
Effects of Overhangs on the Performance of ElectrochromicWindows (open access)

Effects of Overhangs on the Performance of ElectrochromicWindows

None
Date: December 1, 2005
Creator: Tavil, Aslihan & Lee, Eleanor S.
System: The UNT Digital Library
Electromagnetic logarithms in anti-B ---> X(s) l+ l- (open access)

Electromagnetic logarithms in anti-B ---> X(s) l+ l-

None
Date: December 1, 2005
Creator: Huber, Tobias; Lunghi, Enrico; Misiak, Mikolaj & Wyler, Daniel
System: The UNT Digital Library
Ensemble Atmospheric Modelingfor Emergency Response in Support of Federal Consequence Assessments (open access)

Ensemble Atmospheric Modelingfor Emergency Response in Support of Federal Consequence Assessments

None
Date: December 1, 2005
Creator: Addis, Robert P. & Merrick, John L., Jr.
System: The UNT Digital Library
ESL Startup Workshop (open access)

ESL Startup Workshop

None
Date: December 1, 2005
Creator: Cohen, R H
System: The UNT Digital Library
Expected accuracy in a measurement of the CKM angle alpha using a Dalitz plot analysis of B0 ---> rho pi decays in the BTeV project (open access)

Expected accuracy in a measurement of the CKM angle alpha using a Dalitz plot analysis of B0 ---> rho pi decays in the BTeV project

A precise measurement of the angle {alpha} in the CKM triangle is very important for a complete test of Standard Model. A theoretically clean method to extract {alpha} is provided by B{sup 0} {yields} {rho}{pi} decays. Monte Carlo simulations to obtain the BTeV reconstruction efficiency and to estimate the signal to background ratio for these decays were performed. Finally the time-dependent Dalitz plot analysis, using the isospin amplitude formalism for tre and penguin contributions, was carried out. It was shown that in one year of data taking BTeV could achieve an accuracy on {alpha} better than 5{sup o}.
Date: December 1, 2005
Creator: Shestermanov, K.E.; Vasiliev, A.N; /Serpukhov, IHEP; Butler, J.; Derevschikov, A.A.; Kasper, P. et al.
System: The UNT Digital Library
First observations of separated atmospheric nu(mu) and anti-nu(mu) events in the MINOS detector (open access)

First observations of separated atmospheric nu(mu) and anti-nu(mu) events in the MINOS detector

None
Date: December 1, 2005
Creator: Adamson, P.; Alexopoulos, T.; Allison, W. W. M.; Alner, G. J.; Anderson, K.; Andreopoulos, C. et al.
System: The UNT Digital Library