Language

Performance and Accountability Highlights Fiscal Year 2005 (open access)

Performance and Accountability Highlights Fiscal Year 2005

Other written product issued by the Government Accountability Office with an abstract that begins "This report presents the highlights of GAO's fiscal year 2005 Performance and Accountability report. In short, fiscal year 2005 was an exceptional year for GAO. For example, we received a clean opinion from independent auditors on our financial statements and met or exceeded targets for 10 of 14 key performance measures, while setting or matching all-time records for 3 measures. We documented $39.6 billion in financial benefits--a return of $83 for every dollar we spent--and over 1,400 nonfinancial benefits--a record for us. The work we did to produce these benefits helped to shape important legislation, such as the Intelligence Reform and Terrorism Prevention Act of 2004 (Pub. L. No. 108-458), and increase the efficiency of various federal programs, thus improving the lives of millions of Americans. In addition, the rate at which our recommendations were implemented by the Congress or federal agencies rose to 85 percent in fiscal year 2005, and the percentage of our fiscal year 2005 products containing recommendations increased to 63 percent--exceeding the targets we set for both of these measures this year. In addition, in the first year that we are reporting …
Date: January 1, 2006
Creator: United States. Government Accountability Office.
Object Type: Text
System: The UNT Digital Library
Tolerance of Three-Stage CIGS Deposition to Variations Imposed by Roll-to-Roll Processing: Final Technical Report, May 2003 - September 2005 (open access)

Tolerance of Three-Stage CIGS Deposition to Variations Imposed by Roll-to-Roll Processing: Final Technical Report, May 2003 - September 2005

Three-stage co-evaporation of CIGS imposes stringent limits on the parameter space if high-efficient devices are to result. Substrate temperatures during the 1st stage (as well as during the 2nd and 3rd stage), Se partial pressure, and amount of Na supplied are critical for good nucleation, proper In-Ga-selenide precursor phase, and diffusion of Cu into the precursor, as well as diffusion of Ga through the film. In addition, the degree of Cu-rich excursion impacts maximum performance and process tolerance. Enveloping the above is the basic time-temperature profile inextricably linked to the metals delivery rates. Although high-efficiency, three-stage deposited CIGS devices on the R&D scale are grown at about 20-45 minutes to thicknesses of 2 to 2.5 m, the latter is not a viable approach for an economic manufacturing process. At Global Solar Energy, Inc., CIGS films are typically grown in about 6 minutes to thicknesses of less than 2 m. At the same time, the emissivity and thermal conductivity of stainless steel is vastly different from that of glass, and the reduced growth time poses restrictions on the substrate temperature ramp rates and diffusion of species (reaction kinetics). Material compatibility in the highly corrosive Se environment places limitations on the substrate …
Date: January 1, 2006
Creator: Beck, M. E. & Britt, J. S.
Object Type: Report
System: The UNT Digital Library
Testing State-Space Controls for the Controls Advanced Research Turbine: Preprint (open access)

Testing State-Space Controls for the Controls Advanced Research Turbine: Preprint

Control can improve wind turbine performance by enhancing energy capture and reducing dynamic loads. At the National Renewable Energy Laboratory, we are implementing and testing state-space controls on the Controls Advanced Research Turbine (CART), a turbine specifically configured to test advanced controls. We show the design of control systems to regulate turbine speed in Region 3 using rotor collective pitch and reduce dynamic loads in Regions 2 and 3 using generator torque. These controls enhance damping in the first drive train torsion mode. We base these designs on sensors typically used in commercial turbines. We evaluate the performance of these controls by showing field test results. We also compare results from these modern controllers to results from a baseline proportional integral controller for the CART. Finally, we report conclusions to this work and outline future studies.
Date: January 1, 2006
Creator: Wright, A. D.; Fingersh, L. J. & Balas, M. J.
Object Type: Article
System: The UNT Digital Library
Save Energy Now (open access)

Save Energy Now

This DOE Industrial Technologies Program brochure informs industrial audiences about Save Energy Now, part of ''Easy Ways to Save Energy'', a national campaign to save energy and ensure energy security.
Date: January 1, 2006
Creator: unknown
Object Type: Report
System: The UNT Digital Library
Optical Blade Position Tracking System Test (open access)

Optical Blade Position Tracking System Test

The Optical Blade Position Tracking System Test measures the blade deflection along the span of the blade using simple off-the-shelf infrared security cameras along with blade-mounted retro-reflective tape and video image processing hardware and software to obtain these measurements.
Date: January 1, 2006
Creator: Fingersh, L. J.
Object Type: Report
System: The UNT Digital Library
Process R&D for CIS-Based Thin-Film PV: Final Technical Report, April 2002 - April 2005 (open access)

Process R&D for CIS-Based Thin-Film PV: Final Technical Report, April 2002 - April 2005

The primary objectives of this Shell Solar Industries subcontract are to address key near-term technical R&D issues for continued CIS product improvement; continue process development for increased production capacity; develop processes capable of significantly contributing to DOE 2020 PV shipment goals; advance mid- and longer-term R&D needed by industry for future product competitiveness including improving module performance, decreasing production process costs per watt produced, and improving reliability; and perform aggressive module lifetime R&D directed at developing packages that address the DOE goal for modules that will last up to 30 years while retaining 80% of initial power. These production R&D results, production volume, efficiency, high line yield, and advances in understanding are major accomplishments. The demonstrated and maintained high production yield is a major accomplishment supporting attractive cost projections for CIS. Process R&D at successive levels of CIS production has led to the continued demonstration of the prerequisites for commitment to large-scale commercialization. Process and packaging R&D during this and previous subcontracts has demonstrated the potential for further cost and performance improvements.
Date: January 1, 2006
Creator: Tarrant, D. E. & Gay, R. R.
Object Type: Report
System: The UNT Digital Library
The Gayly Oklahoman (Oklahoma City, Okla.), Vol. 24, No. 1, Ed. 1 Sunday, January 1, 2006 (open access)

The Gayly Oklahoman (Oklahoma City, Okla.), Vol. 24, No. 1, Ed. 1 Sunday, January 1, 2006

Semi-monthly newspaper from Oklahoma City, Oklahoma that includes local, state, and national news and advertising of interest to the Lesbian, Gay, Bisexual, and Transgender (LGBT) community.
Date: January 1, 2006
Creator: Hawkins, Don
Object Type: Newspaper
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
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
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
Conductivity Measurements of Synthesized Heteropoly Acid Membranes for Proton Exchange Membrane Fuel Cells (open access)

Conductivity Measurements of Synthesized Heteropoly Acid Membranes for Proton Exchange Membrane Fuel Cells

Fuel cell technology is receiving attention due to its potential to be a pollution free method of electricity production when using renewably produced hydrogen as fuel. In a Proton Exchange Membrane (PEM) fuel cell H2 and O2 react at separate electrodes, producing electricity, thermal energy, and water. A key component of the PEM fuel cell is the membrane that separates the electrodes. DuPont’s Nafion® is the most commonly used membrane in PEM fuel cells; however, fuel cell dehydration at temperatures near 100°C, resulting in poor conductivity, is a major hindrance to fuel cell performance. Recent studies incorporating heteropoly acids (HPAs) into membranes have shown an increase in conductivity and thus improvement in performance. HPAs are inorganic materials with known high proton conductivities. The primary objective of this work is to measure the conductivity of Nafion, X-Ionomer membranes, and National Renewable Energy Laboratory (NREL) Developed Membranes that are doped with different HPAs at different concentrations. Four-point conductivity measurements using a third generation BekkTech conductivity test cell are used to determine membrane conductivity. The effect of multiple temperature and humidification levels is also examined. While the classic commercial membrane, Nafion, has a conductivity of approximately 0.10 S/cm, measurements for membranes in this …
Date: January 1, 2006
Creator: Record, K. A.; Haley, B. T. & Turner, J.
Object Type: Article
System: The UNT Digital Library
Conditioned Place Preference to Acetone Inhalation and the Effects on Locomotor Behavior and 18FDG Uptake (open access)

Conditioned Place Preference to Acetone Inhalation and the Effects on Locomotor Behavior and 18FDG Uptake

Acetone is a component in many inhalants that have been widely abused. While other solvents have addictive potential, such as toluene, it is unclear whether acetone alone contains addictive properties. The locomotor, relative glucose metabolism and abusive effects of acetone inhalation were studied in animals using the conditioned place preference (CPP) paradigm and [18F]2-fluorodeoxy-D-glucose (18FDG) imaging. The CPP apparatus contains two distinct conditioning chambers and a middle adaptation chamber, each lined with photocells to monitor locomotor activity. Adolescent Sprague-Dawley rats (n=16; 90-110 g) were paired with acetone in least preferred conditioning chamber, determined on the pretest day. The animals were exposed to a 10,000 ppm dose for an hour, alternating days with air. A CPP test was conducted after the 3rd, 6th and 12th pairing. In these same animals, the relative glucose metabolism effects were determined using positron emission tomography (PET) imaging with 18FDG. Following the 3rd pairing, there was a significant aversion to the acetone paired chamber (190.9 ± 13.7 sec and 241.7 ± 16.9 sec, acetone and air, respectively). After the 6th pairing, there was no significant preference observed with equal time spent in each chamber (222 ± 21 sec and 207 ± 20 sec, acetone and air-paired, …
Date: January 1, 2006
Creator: Pai, J.C.; Dewey, S.L.; Schiffer, W. & Lee, D.
Object Type: Article
System: The UNT Digital Library
Magnetization, Charge Transport , and Stripe Phases in Nd5/3Sr1/3NiO4+δ Single Crystal (open access)

Magnetization, Charge Transport , and Stripe Phases in Nd5/3Sr1/3NiO4+δ Single Crystal

Stripe phases, in which doped charges are localized along domain walls between antiferromagnetic insulating regions, provide a framework for the electronic structure of doped antiferromagnets such as the superconducting layered copper-oxides. Layered nickel-oxides, such as Nd2–χSrχNiO4, though non-superconducting, exhibit stripe phases in which charges are more localized, resulting in higher charge density modulation amplitudes than their cuprate analogs, thus are more amenable for experimental investigations. We study the magnetic and electric-transport properties of a Nd5/3Sr1/3NiO4+δ single crystal by means of magnetic susceptibility, isothermal magnetization, and electric resistivity measurements. We observe a transition of the magnetic susceptibility with applied field parallel to the c-axis at T ≈ 15 K, which is due to the long-range ordering of Nd3+ magnetic moments. A transition of the in-plane resistivity (ρab) is observed at T ≈ 230 K, which indicates the charge stripe ordering that has also been observed in La2–χSrχNiO4 at about the same temperature. The out-of-plane resistivity (ρc) exhibits a milder transition at T ≈ 200 K. After the stripe phase transition takes place, the electronic transport exhibits variable range hopping behavior. The resistivity anisotropy (ρc /ρab) shows a sharp drop at the ρab transition temperature with decreasing temperature, which indicates the strong …
Date: January 1, 2006
Creator: Zhang, J. Z. & Hucker, M.
Object Type: Article
System: The UNT Digital Library
Silicon Nitride for Direct Water-Splitting and Corrosion Mitigation (open access)

Silicon Nitride for Direct Water-Splitting and Corrosion Mitigation

Todays fossil fuels are becoming harder to obtain, creating pollution problems, and posing hazards to people’s health. One alternative to fossil fuels is hydrogen, capable of serving as a clean and efficient energy carrier. Certain semiconductors are able to harness the energy of photons and direct it into water electrolysis in a process known as photoelectrochemical water splitting. Triple junction devices integrate three semiconductors of different band gaps resulting in a monolithic material that absorbs over a broader spectrum. Amorphous silicon (a-Si) is one such material that, when stacked in tandem, possesses water-splitting capabilities. Even though a-Si is capable of splitting water, it is an unstable material in solution and therefore requires a coating to protect the surface from corrosion. A stable, transparent material that has the potential for corrosion protection is silicon nitride. In this study, silicon nitride thin films were grown using DC magnetron sputtering with varying amounts of argon and nitrogen added to the system. X-ray diffraction indicated amorphous silicon nitride films. Current as a function of potential was determined from cyclic voltammetry measurements. Mott-Schottky analysis showed n-type behavior with absorption and transmission measurements indicated variation in flatband potentials. Variation in band gap values ranging from 1.90 …
Date: January 1, 2006
Creator: Head, J. & Turner, J.A.
Object Type: Article
System: The UNT Digital Library
Olivine Composite Cathode Materials for Improved Lithium Ion Battery Performance (open access)

Olivine Composite Cathode Materials for Improved Lithium Ion Battery Performance

Composite cathode materials in lithium ion batteries have become the subject of a great amount of research recently as cost and safety issues related to LiCoO2 and other layered structures have been discovered. Alternatives to these layered materials include materials with the spinel and olivine structures, but these present different problems, e.g. spinels have low capacities and cycle poorly at elevated temperatures, and olivines exhibit extremely low intrinsic conductivity. Previous work has shown that composite structures containing spinel and layered materials have shown improved electrochemical properties. These types of composite structures have been studied in order to evaluate their performance and safety characteristics necessary for use in lithium ion batteries in portable electronic devices, particularly hybrid-electric vehicles. In this study, we extended that work to layered-olivine and spinel-olivine composites. These materials were synthesized from precursor salts using three methods: direct reaction, ball-milling, and a coreshell synthesis method. X-ray diffraction spectra and electrochemical cycling data show that the core-shell method was the most successful in forming the desired products. The electrochemical performance of the cells containing the composite cathodes varied dramatically, but the low overpotential and reasonable capacities of the spinel-olivine composites make them a promising class for the next generation …
Date: January 1, 2006
Creator: Ward, R. M. & Vaughey, J. T.
Object Type: Article
System: The UNT Digital Library
Analysis of the Habitat of Henslow's Sparrows and Grasshopper Sparrows Compared to Random Grassland Areas (open access)

Analysis of the Habitat of Henslow's Sparrows and Grasshopper Sparrows Compared to Random Grassland Areas

ABSTRAC T Henslow’s Sparrows are endangered prairie birds, and Grasshopper Sparrows are considered rare prairie birds. Both of these birds were abundant in Illinois, but their populations have been declining due to loss of the grasslands. This begins an ongoing study of the birds’ habitat so Fermilab can develop a land management plan for the Henslow’s and Grasshoppers. The Henslow’s were found at ten sites and Grasshoppers at eight sites. Once the birds were located, the vegetation at their sites was studied. Measurements of the maximum plant height, average plant height, and duff height were taken and estimates of the percent of grass, forbs, duff, and bare ground were recorded for each square meter studied. The same measurements were taken at ten random grassland sites on Fermilab property. Several t-tests were performed on the data, and it was found that both Henslow’s Sparrows and Grasshopper Sparrows preferred areas with a larger percentage of grass than random areas. Henslow’s also preferred areas with less bare ground than random areas, while Grasshoppers preferred areas with more bare ground than random areas. In addition, Grasshopper Sparrows preferred a lower percentage of forbs than was found in random areas and a shorter average plant …
Date: January 1, 2006
Creator: Maier, K.; Walton, R. & Kasper, P.
Object Type: Article
System: The UNT Digital Library
Analysis of B → ωlν Decays With BaBar (open access)

Analysis of B → ωlν Decays With BaBar

As part of the BaBar project at SLAC to study the properties of B mesons, we have carried out a study of the exclusive charmless semileptonic decay mode B → ωlν, which can be used to determine the magnitude of the Cabbibo- Kobayashi-Maskawa matrix element Vub. Using simulated event samples, this study focuses on determining criteria on variables for selection of B → ωlν signal and suppression of background from other types of BB events and continuum processes. In addition, we determine optimal cuts on variables to ensure a good neutrino reconstruction. With these selection cuts, we were able to achieve a signal-to-background ratio of 0.68 and a signal efficiency of the order of 1%. Applying these cuts to a sample of 83 million BB events recorded by BaBar in e+e– collisions at the (4S) resonance, we obtain a yield of 115 ± 19 B → ωlν decays.
Date: January 1, 2006
Creator: Chu, Yiwen; Littlejohn, Bryce & Binfelder, J.
Object Type: Article
System: The UNT Digital Library