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Obligate autotrophy in the ammonia oxidizing bacterium Nitrosomonas europaea. (open access)

Obligate autotrophy in the ammonia oxidizing bacterium Nitrosomonas europaea.

Closing report for project DOE-FG02-03ER15436. The project studied obligate autotrophy in the ammonia oxidizing bacterium Nitrosomonas europaea. Nitrosomonas europaea can obtain all of its energy and reductant for growth from the oxidation of ammonia to nitrite and is, therefore, classified as a chemolithotroph. This bacterium is also an autotroph, which can derive all cellular carbon from carbon dioxide. N. europaea seems incapable of growth with other carbon or energy sources. This restricted capability is surprising given that ammonia is a poor energy source. The main goal of the project was to examine the basis of autotrophy in N. europaea or, thought of another way, to determine the barriers to heterotrophy. The approach was enabled by the N. europaea genome sequence, stimulating new ways of thinking about this physiological paradox—an insistence on a single, albeit poor, energy source. Objective 1 was to examine the expression and regulation of the genes coding for alpha-ketoglutarate dehydrogenase, determine if the enzyme’s activity is present, and determine whether alteration of the expression levels influences autotrophic growth. Although Nitrosomonas europaea lacks measurable alpha-ketoglutarate dehydrogenase activity, the genome sequence revealed the presence of the genes encoding the enzyme. A knockout mutation was created in the sucA gene …
Date: January 1, 2006
Creator: Arp, Daniel James & Sayavedra-Soto, Luis Alberto
Object Type: Text
System: The UNT Digital Library
Measurement of the B meson Lifetimes with the Collider Detector at Fermilab (open access)

Measurement of the B meson Lifetimes with the Collider Detector at Fermilab

The lifetimes of the B{sup -}, B{sup 0} and B{sub s}{sup 0} mesons are measured using partially reconstructed semileptonic decays. Following semileptonic decay processes and their charge conjugates are used for this analysis: B{sup -}/B{sup 0} {yields} {ell}{sup -}{nu}D{sup 0}X; B{sup -}/B{sup 0} {yields} {ell}{sup -}{nu}D*{sup +}X; B{sub s}{sup 0} {yields} {ell}{sup -}{nu}D{sub s}{sup +}x, where {ell}{sup -} denotes either a muon or electron. The data are collected during 2002-2004 by the 8 GeV single lepton triggers in CDF Run II at the Fermilab Tevatron Collider. Corresponding integrated luminosity is about 260 and 360 pb{sup -1} used for the B{sup -}/B{sup 0} and B{sub s}{sup 0} lifetime analyses, respectively. With the single lepton triggers, events which contain a muon or electron with a transverse momentum greater than 8 GeV/c are selected. For these lepton candidates, further lepton identification cuts are applied to improve purity of the B semileptonic decay signal. After the lepton selection, three types of charm mesons associated with the lepton candidates are reconstructed. Following exclusive decay modes are used for the charm meson reconstruction: D{sup 0} {yields} K{sup -}{pi}{sup +}; D*{sup +} {yields} D{sup 0}{pi}{sub s}{sup +}, followed by D{sup 0} {yields} K{sup -}{pi}{sup +}; D{sub s}{sup …
Date: January 1, 2006
Creator: Uozumi, Satoru
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Simulation analysis of within-day flow fluctuation effects on trout below flaming Gorge Dam. (open access)

Simulation analysis of within-day flow fluctuation effects on trout below flaming Gorge Dam.

In addition to being renewable, hydropower has the advantage of allowing rapid load-following, in that the generation rate can easily be varied within a day to match the demand for power. However, the flow fluctuations that result from load-following can be controversial, in part because they may affect downstream fish populations. At Flaming Gorge Dam, located on the Green River in northeastern Utah, concern has been raised about whether flow fluctuations caused by the dam disrupt feeding at a tailwater trout fishery, as fish move in response to flow changes and as the flow changes alter the amount or timing of the invertebrate drift that trout feed on. Western Area Power Administration (Western), which controls power production on submonthly time scales, has made several operational changes to address concerns about flow fluctuation effects on fisheries. These changes include reducing the number of daily flow peaks from two to one and operating within a restricted range of flows. These changes significantly reduce the value of the power produced at Flaming Gorge Dam and put higher load-following pressure on other power plants. Consequently, Western has great interest in understanding what benefits these restrictions provide to the fishery and whether adjusting the restrictions …
Date: January 1, 2006
Creator: Railsback, S. F.; Hayse, J. W.; LaGory, K. E.; Division, Environmental Science & EPRI
Object Type: Report
System: The UNT Digital Library
Negative Halogen Ions for Fusion Applications (open access)

Negative Halogen Ions for Fusion Applications

Over the past quarter century, advances in hydrogen negative ion sources have extended the usable range of hydrogen isotope neutral beams to energies suitable for large magnetically confined fusion devices. Recently, drawing upon this experience, negative halogen ions have been proposed as an alternative to positive ions for heavy ion fusion drivers in inertial confinement fusion, because electron accumulation would be prevented in negative ion beams, and if desired, the beams could be photo-detached to neutrals. This paper reports the results of an experiment comparing the current density and beam emittance of Cl+ and Cl- extracted from substantially ion-ion plasmas with that of Ar+ extracted from an ordinary electron-ion plasma, all using the same source, extractor, and emittance scanner. At similar discharge conditions, the Cl- current was typically 85 – 90% of the positive chlorine current, with an e-/ Cl- ratio as low as seven without grid magnets. The Cl- was as much as 76% of the Ar+ current from a discharge with the same RF drive. The minimum normalized beam emittance and inferred ion temperatures of Cl+, Cl-, and Ar+ were all similar, so the current density and optical quality of Cl- appear as suitable for heavy ion fusion …
Date: January 1, 2006
Creator: Grisham, L. R.; Kwan, J. W.; Hahto, S. K.; Hahto, S. T.; Leung, K. N. & Westenskow, G.
Object Type: Article
System: The UNT Digital Library
Actinic Inspection of EUV Programmed Multilayer Defects andCross-comparison Measurements (open access)

Actinic Inspection of EUV Programmed Multilayer Defects andCross-comparison Measurements

This article is about the Actinic Inspection of Extreme Ultraviolet (EUV) lithography Programmed Multilayer Defects and cross-comparison Measurements.
Date: January 1, 2006
Creator: Goldberg, Kenneth A.; Barty, Anton; Liu, Yanwei; Kearney,Patrick; Tezuka, Yoshihiro; Terasawa, Tsuneo et al.
Object Type: Article
System: The UNT Digital Library
Testing the Specificity of Primers to Environmental Ammonia Monooxygenase (amoA) Genes in Groundwater Treated with Urea to Promote Calcite Precipitation (open access)

Testing the Specificity of Primers to Environmental Ammonia Monooxygenase (amoA) Genes in Groundwater Treated with Urea to Promote Calcite Precipitation

Bacterial ammonia monooxygenase (amoA) genes in DNA isolated from microorganisms in groundwater were characterized by amplification of amoA DNA using polymerase chain reaction (PCR), Restriction Fragment Length Polymorphism (RFLP) analysis, and sequencing. The amoA gene is characteristic of ammonia oxidizing bacteria (AOB). The DNA extracts were acquired from an experiment where dilute molasses and urea were sequentially introduced into a well in the Eastern Snake River Plain Aquifer (ESRPA) in Idaho to examine whether such amendments could stimulate enhanced ureolytic activity. The hydrolysis of urea into ammonium and carbonate serves as the basis for a potential remediation technique for trace metals and radionuclide contaminants that can co-precipitate in calcite. The ammonium ion resulting from ureolysis can promote the growth of AOB. The goal of this work was to investigate the effectiveness of primers designed for quantitative PCR of environmental amoA genes and to evaluate the effect of the molasses and urea amendments upon the population diversity of groundwater AOB. PCR primers designed to target a portion of the amoA gene were used to amplify amoA gene sequences in the groundwater DNA extracts. Following PCR, amplified gene products were cloned and the clones were characterized by RFLP, a DNA restriction technique …
Date: January 1, 2006
Creator: Freeman, S.; Reed, D.W. & Fujita, Y.
Object Type: Article
System: The UNT Digital Library
Physiological Adjustments of Leaf Respiration to Atmospheric Warming in Betula alleghaniensis and Quercus rubra (open access)

Physiological Adjustments of Leaf Respiration to Atmospheric Warming in Betula alleghaniensis and Quercus rubra

Global air temperatures are predicted to rise 1° to 4.5° Celsius by the year 2100. This climatic change is expected to have a great effect on the succession and migration of temperate deciduous forest species. Most physiologically based models of forest response to climatic change focus on the ecosystems as a whole instead of on individual tree species, assuming that the effects of warming on respiration are generally the same for each species, and that processes can not adjust to a changing climate. Experimental data suggest that physiological adjustments are possible, but there is a lack of data in deciduous species. In order to correctly model the effects of climate change on temperate species, species-specific respiration acclimation (adjustment) to rising temperatures is being determined in this experiment. Two temperate deciduous tree species Betula alleghaniensis (BA) and Quercus rubra (QR) were grown over a span of four years in open-top chambers and subjected to two different temperature treatments; ambient and ambient plus 4° Celsius (E4). Between 0530 hours and 1100 hours, respiration was measured over a range of leaf temperatures on several comparable, fully expanded leaves in each treatment. Circular punches were taken from the leaves and dried at 60°C to …
Date: January 1, 2006
Creator: Vollmar, A. & Gunderson, C.
Object Type: Article
System: The UNT Digital Library
Journal of Undergraduate Research, Volume 6, 2006 (open access)

Journal of Undergraduate Research, Volume 6, 2006

None
Date: January 1, 2006
Creator: Faletra, P.; Schuetz, A.; Cherkerzian, D & Clark, T.
Object Type: Journal/Magazine/Newsletter
System: The UNT Digital Library
Eddy Current Imaging of Machined Grooves on a Nickel Wave Strip (open access)

Eddy Current Imaging of Machined Grooves on a Nickel Wave Strip

White paper proposal to client at Y-12 for eddy current inspection
Date: January 1, 2006
Creator: Andersen, Eric S.; Mathews, Royce & Sandness, Gerald A.
Object Type: Report
System: The UNT Digital Library
Failure Atlas for Rolling Bearings in Wind Turbines (open access)

Failure Atlas for Rolling Bearings in Wind Turbines

This Atlas is structured as a supplement to the book: T.E. Tallian: Failure Atlas for Hertz Contact Machine Elements, 2nd edition, ASME Press New York, (1999). The content of the atlas comprises plate pages from the book that contain bearing failure images, application data, and descriptions of failure mode, image, and suspected failure causes. Rolling bearings are a critical component of the mainshaft system, gearbox and generator in the rapidly developing technology of power generating wind turbines. The demands for long service life are stringent; the design load, speed and temperature regimes are demanding and the environmental conditions including weather, contamination, impediments to monitoring and maintenance are often unfavorable. As a result, experience has shown that the rolling bearings are prone to a variety of failure modes that may prevent achievement of design lives. Morphological failure diagnosis is extensively used in the failure analysis and improvement of bearing operation. Accumulated experience shows that the failure appearance and mode of failure causation in wind turbine bearings has many distinguishing features. The present Atlas is a first effort to collect an interpreted database of specifically wind turbine related rolling bearing failures and make it widely available. This Atlas is structured as a …
Date: January 1, 2006
Creator: Tallian, T. E.
Object Type: Report
System: The UNT Digital Library
Characterization of a TK6-Bcl-xL gly-159-ala Human Lymphoblast Clone (open access)

Characterization of a TK6-Bcl-xL gly-159-ala Human Lymphoblast Clone

TK6 cells are a well-characterized human B-lymphoblast cell line derived from WIL-2 cells. A derivative of the TK6 cell line that was stably transfected to express a mutated form of the anti-apoptotic protein Bcl-xL (TK6-Bcl-xL gly-159- ala clone #38) is compared with the parent cell line. Four parameters were evaluated for each cell line: growth under normal conditions, plating efficiency, and frequency of spontaneous mutation to 6‑thioguanine resistance (hypoxanthine phosphoribosyl transferase locus) or trifluorothymidine resistance (thymidine kinase locus). We conclude that the mutated Bcl-xL protein did not affect growth under normal conditions, plating efficiency or spontaneous mutation frequencies at the thymidine kinase (TK) locus. Results at the hypoxanthine phosphoribosyl transferase (HPRT) locus were inconclusive. A mutant fraction for TK6‑Bcl-xL gly-159-ala clone #38 cells exposed to 150cGy of 160kVp x-rays was also calculated. Exposure to x-irradiation increased the mutant fraction of TK6‑Bcl-xL gly-159-ala clone #38 cells.
Date: January 1, 2006
Creator: Chyall, L.: Gauny, S. & Kronenberg, A.
Object Type: Article
System: The UNT Digital Library
Ordered Nucleation Sites for the Growth of Zinc Oxide Nanofibers (open access)

Ordered Nucleation Sites for the Growth of Zinc Oxide Nanofibers

Organic photovoltaics (OPVs) offer a promising route to low cost photovoltaic (PV) technology that can be inexpensively manufactured on a large scale for use in power generation and commercial products. Solar power conversion efficiencies of laboratory scale OPV devices have recently reached ~5%; however, projected efficiencies of at least 10% will be required for commercialization. An analogous approach that has arisen recently that can potentially increase efficiencies employs metal oxide semiconductors as the electron acceptor, creating a hybrid organic-inorganic device. This approach offers the advantage that the conduction band of the oxide can be tuned in a systematic way through doping, thus potentially achieving higher photovoltages in the device. Additionally, nanostructures of these materials can be easily grown from precursor solutions, providing a technique to precisely control the nanoscale geometry. This work focuses on using ZnO, which is known to have high electron mobility (>100 cm2/Vs), as the electron acceptor. Nanofibers of ZnO can be grown from precursors such as zinc acetate or zinc nitrate to form arrays of nanofibers into which a conjugated polymer can be intercalated to form a composite PV device. The morphology of the nanofiber array is critical to the performance of the device, but current …
Date: January 1, 2006
Creator: Wang, J.; Ginley, D.S. & Shaheen, S.
Object Type: Article
System: The UNT Digital Library
Characterizing the Performance of a Proton-Transfer-Reaction Mass Spectrometer with a Rapid Cycling Tenax Preconcentrator (open access)

Characterizing the Performance of a Proton-Transfer-Reaction Mass Spectrometer with a Rapid Cycling Tenax Preconcentrator

Volatile organic compounds (VOCs) are species of interest for atmospheric modeling, worker chemical exposure and medical studies. Sometimes the required detection limits for these compounds is below the capability of existing real-time instrumentation. Preconcentrators have been implemented as an inexpensive way to amplify chemical signals and improve detection limits. Proton-transfer-reaction mass spectrometry (PTR-MS) has been used as a tool for studying low concentrations of VOCs, but it lacks the capability to differentiate chemical signal contributions from isobaric compounds. In this work, behavior of a newly designed Tenax TA preconcentrator when coupled with a PTRMS is characterized. This novel preconcentrator design allows rapid temperature cycling, maintaining near real-time response. The preconcentrator was exposed to a sample gas of toluene in varying concentrations and loading times between and then thermally desorbed for analysis by PTR-MS. The effects of preconcentrating multiple analytes simultaneously were also investigated as well as the chromatographic effects of the preconcentrator. A linear behavior was observed when the integrated ion count rates (ICPS) from thermal desorption peaks were regressed against both varying loading times at a constant toluene concentration and varying concentrations with constant loading times. From these trends, it is possible to determine the concentration of a VOC …
Date: January 1, 2006
Creator: Garland, S.P. & Alexander, M.L.
Object Type: Article
System: The UNT Digital Library
Hydraulic Characteristics of the Lower Snake River during Periods of Juvenile Fall Chinook Salmon Migration, 2002-2006 Final Report. (open access)

Hydraulic Characteristics of the Lower Snake River during Periods of Juvenile Fall Chinook Salmon Migration, 2002-2006 Final Report.

This report documents a four-year study to assess hydraulic conditions in the lower Snake River. The work was conducted for the Bonneville Power Administration, U.S. Department of Energy, by the Pacific Northwest National Laboratory. Cold water released from the Dworshak Reservoir hypolimnion during mid- to late-summer months cools the Clearwater River far below equilibrium temperature. The volume of released cold water augments the Clearwater River, and the combined total discharge is on the order of the Snake River discharge when the two rivers meet at their confluence near the upstream edge of Lower Granite Reservoir. With typical temperature differences between the Clearwater and Snake rivers of 10 C or more during July and August, the density difference between the two rivers during summer flow augmentation periods is sufficient to stratify Lower Granite Reservoir as well as the other three reservoirs downstream. Because cooling of the river is desirable for migrating juvenile fall Chinook salmon (Oncorhynchus tshawytscha) during this same time period, the amount of mixing and cold water entrained into Lower Granite Reservoir's epilimnion at the Clearwater/Snake River confluence is of key biological importance. Data collected during this project indicates the three reservoirs downstream of Lower Granite also stratify as …
Date: January 1, 2006
Creator: Cook, C.; Dibrani, B.; Richmond, M.; Bleich, M.; Titzler, P.. & Fu, T.
Object Type: Report
System: The UNT Digital Library
Applicability of Related Data, Algorithms, and Models to the Simulation of Ground-Coupled Residential Hot Water Piping in California (open access)

Applicability of Related Data, Algorithms, and Models to the Simulation of Ground-Coupled Residential Hot Water Piping in California

Residential water heating is an important consideration in California?s building energy efficiency standard. Explicit treatment of ground-coupled hot water piping is one of several planned improvements to the standard. The properties of water, piping, insulation, backfill materials, concrete slabs, and soil, their interactions, and their variations with temperature and over time are important considerations in the required supporting analysis. Heat transfer algorithms and models devised for generalized, hot water distribution system, ground-source heat pump and ground heat exchanger, nuclear waste repository, buried oil pipeline, and underground electricity transmission cable applications can be adapted to the simulation of under-slab water piping. A numerical model that permits detailed examination of and broad variations in many inputs while employing a technique to conserve computer run time is recommended.
Date: January 1, 2006
Creator: Warner, J. L. & Lutz, J. D.
Object Type: Report
System: The UNT Digital Library
Selection and Characterization of Carbon Black and Surfactants for Development of Small Scale Uranium Oxicarbide Kernels (open access)

Selection and Characterization of Carbon Black and Surfactants for Development of Small Scale Uranium Oxicarbide Kernels

This report supports the effort for development of small scale fabrication of UCO (a mixture of UO{sub 2} and UC{sub 2}) fuel kernels for the generation IV high temperature gas reactor program. In particular, it is focused on optimization of dispersion conditions of carbon black in the broths from which carbon-containing (UO{sub 2} {center_dot} H{sub 2}O + C) gel spheres are prepared by internal gelation. The broth results from mixing a hexamethylenetetramine (HMTA) and urea solution with an acid-deficient uranyl nitrate (ADUN) solution. Carbon black, which is previously added to one or other of the components, must stay dispersed during gelation. The report provides a detailed description of characterization efforts and results, aimed at identification and testing carbon black and surfactant combinations that would produce stable dispersions, with carbon particle sizes below 1 {micro}m, in aqueous HMTA/urea and ADUN solutions. A battery of characterization methods was used to identify the properties affecting the water dispersability of carbon blacks, such as surface area, aggregate morphology, volatile content, and, most importantly, surface chemistry. The report introduces the basic principles for each physical or chemical method of carbon black characterization, lists the results obtained, and underlines cross-correlations between methods. Particular attention is given …
Date: January 1, 2006
Creator: Contescu, Cristian I.
Object Type: Report
System: The UNT Digital Library
Linearity Testing of Photovoltaic Cells (open access)

Linearity Testing of Photovoltaic Cells

Photovoltaic devices are rated in terms of their power output or efficiency with respect to a specific spectrum, total irradiance, and temperature. In order to rate photovoltaic devices, a reference detector whose response is linear with total irradiance is needed. This procedure documents a procedure to determine if a detector is linear over the irradiance range of interest. Testing the short circuit current versus the total irradiance is done by illuminating a reference cell candidate with two lamps that are fitted with programmable filter wheels. The purpose is to reject nonlinear samples as determined by national and international standards from being used as primary reference cells. A calibrated linear reference cell tested by the two lamp method yields a linear result.
Date: January 1, 2006
Creator: Pinegar, S.; Nalley, D. & Emery, K.
Object Type: Article
System: The UNT Digital Library
Development of an Auto-Convergent Free-Boundary Axisymmetric Equilibrium Solver (open access)

Development of an Auto-Convergent Free-Boundary Axisymmetric Equilibrium Solver

The calculation of the magnetic flux given an assumed value for the current profile in axisymmetric toroidal plasmas is essential in studying the effects of various magnetohydrodynamic (MHD) instabilities upon controlled fusion. To this end, an iterative, modular algorithm coupled with a fast, direct elliptic solver for the Grad-Shafranov equation has been used to reconstruct the desired free-boundary equilibrium solution. This free-boundary Grad-Shafranov (FBGS) equilibrium algorithm is modified with the application of the von Hagenow method for determining the flux on the computational boundary, greatly reducing the time cost from O(N3) to O(N2 ln N) machine operations as compared to current Green’s function methods. The inherent variance in implementing the von Hagenow method gives a mean error bound of 0.1 percent with respect to the normal Green’s method. The improvements will allow the grid resolution to be increased efficiently and automatically to reduce the maximum Grad-Shafranov error to values needed for accurate stability calculations on a more effective time scale.
Date: January 1, 2006
Creator: Huang, J. & Menard, J.
Object Type: Article
System: The UNT Digital Library
Dependence of Fracture Toughness on Crystallographic Orientation in Single-Crystalline Cubic (β) Silicon Carbide (open access)

Dependence of Fracture Toughness on Crystallographic Orientation in Single-Crystalline Cubic (β) Silicon Carbide

Along with other desirable properties, the ability of silicon carbide (SiC) to retain high strength after elevated temperature exposures to neutron irradiation renders it potentially applicable in fusion and advanced fission reactors. However, properties of the material such as room temperature fracture toughness must be thoroughly characterized prior to such practical applications. The objective of this work is to investigate the dependence of fracture toughness on crystallographic orientation for single-crystalline β-SiC. X-ray diffraction was first performed on the samples to determine the orientation of the crystal. Nanoindentation was used to determine a hardness of 39.1 and 35.2 GPa and elastic modulus of 474 and 446 GPa for the single-crystalline and polycrystalline samples, respectively. Additionally, crack lengths and indentation diagonals were measured via a Vickers micro-hardness indenter under a load of 100 gf for different crystallographic orientations with indentation diagonals aligned along fundamental cleavage planes. Upon examination of propagation direction of cracks, the cracks usually did not initiate and propagate from the corners of the indentation where the stresses are concentrated but instead from the indentation sides. Such cracks clearly moved along the {1 1 0} family of planes (previously determined to be preferred cleavage plane), demonstrating that the fracture toughness …
Date: January 1, 2006
Creator: Pharr, M.; Katoh, Y. & Bei, H.
Object Type: Article
System: The UNT Digital Library
Surface and Tower Meteorological Instrumentation at Atqasuk (METTWR2H) Handbook (open access)

Surface and Tower Meteorological Instrumentation at Atqasuk (METTWR2H) Handbook

The Atqasuk meteorology station (AMET) uses mainly conventional in situ sensors to measure wind speed, wind direction, air temperature, dew point, and humidity mounted on a 10-m tower. It also obtains barometric pressure, visibility and precipitation data from sensors at or near the base of the tower. In addition, a chilled mirror hygrometer (CMH) is located at 1 m for comparison purposes. Temperature and relative humidity (RH) probes are mounted at 2 m and 5 m on the tower.
Date: January 1, 2006
Creator: Ritsche, MT
Object Type: Report
System: The UNT Digital Library
Plains CO2 Reduction (PCOR) Partnership (Phase I) Final Report (open access)

Plains CO2 Reduction (PCOR) Partnership (Phase I) Final Report

During the period of October 1, 2003, through September 30, 2005, the Plains CO2 Reduction (PCOR) Partnership, identified geologic and terrestrial candidates for near-term practical and environmentally sound carbon dioxide (CO2) sequestration demonstrations in the heartland of North America. The PCOR Partnership region covered nine states and three Canadian provinces. The validation test candidates were further vetted to ensure that they represented projects with (1) commercial potential and (2) a mix that would support future projects both dependent and independent of CO2 monetization. This report uses the findings contained in the PCOR Partnership's two dozen topical reports and half-dozen fact sheets as well as the capabilities of its geographic information system-based Decision Support System to provide a concise picture of the sequestration potential for both terrestrial and geologic sequestration in the PCOR Partnership region based on assessments of sources, sinks, regulations, deployment issues, transportation, and capture and separation. The report also includes concise action plans for deployment and public education and outreach as well as a brief overview of the structure, development, and capabilities of the PCOR Partnership. The PCOR Partnership is one of seven regional partnerships under Phase I of the U.S. Department of Energy National Energy Technology Laboratory's …
Date: January 1, 2006
Creator: Steadman, Edward N.; Daly, Daniel J.; Silva, Lynette L. de; Harju, John A.; Jensen, Melanie D.; O'Leary, Erin M. et al.
Object Type: Report
System: The UNT Digital Library
The W boson production cross section at the LHC through O(alpha**2(s) (open access)

The W boson production cross section at the LHC through O(alpha**2(s)

We compute the {Omicron}({alpha}{sub s}{sup 2}) QCD corrections to the fully differential cross-section pp {yields} WX {yields} {ell}{nu}X, retaining all effects from spin correlations. The knowledge of these corrections makes it possible to calculate with high precision the W boson production rate and acceptance at the LHC, subject to realistic cuts on the lepton and missing energy distributions. For certain choices of cuts we find large corrections when going from next-to-leading order (NLO) to next-to-next-to-leading order (NNLO) in perturbation theory. These corrections are significantly larger than those obtained by parton-shower event generators merged with NLO calculations. Our calculation may be used to assess and significantly reduce the QCD uncertainties in the many studies of W boson production planned at the LHC.
Date: January 1, 2006
Creator: Melnikov, Kirill; U., /Hawaii; Petriello, Frank & /Wisconsin U., Madison /Fermilab
Object Type: Article
System: The UNT Digital Library
The D0 silicon micro-strip tracker (open access)

The D0 silicon micro-strip tracker

The D0 silicon micro-strip tracker (SMT) is part of the D0 upgrade for the Tevatron RunII at Fermilab. The detector has been running successfully since the start of the RunII physics data taking. The tracking and vertexing performance match the expectation from Monte-Carlo studies. An additional inner layer (Layer0) of silicon sensors at R = 1.6cm will be installed in 2005.
Date: January 1, 2006
Creator: Weber, Michael S.
Object Type: Article
System: The UNT Digital Library
Calculation of acceptance and efficiency for neutral D mesons decaying to electron-positrons and rates of pions and kaons faking electron signals at CDF (open access)

Calculation of acceptance and efficiency for neutral D mesons decaying to electron-positrons and rates of pions and kaons faking electron signals at CDF

In the 19th century, the fundamental units of matter were believed to be atoms. Further experiments in the early 20th century demonstrated that protons and neutrons are just two examples of a class of particles called hadrons, and that hadrons are composed of quarks bound together by gluons. This has evolved to today's Standard Model of particle physics (SM) which encapsulates our knowledge of elementary particles and the fundamental forces between them.
Date: January 1, 2006
Creator: Dhaliwal, Daljit K. & U., /Wayne State
Object Type: Report
System: The UNT Digital Library