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Reversible Beta-Hydrogen Elimination of Three-Coordinate Iron(II) Alkyl Complexes: Mechanistic and Thermodynamic Studies

Description: Article discussing mechanistic and thermodynamic studies and reversible beta-hydrogen elimination of three-coordinate iron(II) alkyl complexes.
Date: October 1, 2004
Creator: Vela, Javier; Vaddadi, Sridhar; Cundari, Thomas R., 1964-; Smith, Jeremy M.; Gregory, Elizabeth A.; Lachicotte, Rene J. et al.
Partner: UNT College of Arts and Sciences

In-situ raman microscopy of individual LiNi0.8Co0.15Al0.05O2 particles in the Li-ion battery composite cathode

Description: Kinetic characteristics of Li{sup +} intercalation/deintercalation into/from individual LiNi{sub 0.8}Co{sub 0.15}Al{sub 0.05}O{sub 2} particles in a composite cathode were studied in-situ using Raman microscopy during electrochemical charge-discharge in 1.2 M LiPF{sub 6}, ethylene carbonate (EC): ethyl-methyl carbonate (EMC), 3:7 by volume. Spectroscopic analysis of a cathode that was removed from a tested high-power Li-ion cell, which suffered substantial power and capacity loss, showed that the state of charge (SOC) of oxide particles on the cathode surface was highly non-uniform despite deep discharge of the Li-ion cell at the end of the test. In-situ monitoring of the SOC of selected oxide particles in the composite cathode in a sealed spectro-electrochemical cell revealed that the rate at which particles charge and discharge varied with time and location. The inconsistent kinetic behavior of individual oxide particles was attributed to degradation of the electronically conducting matrix in the composite cathode upon testing. These local micro-phenomena are responsible for the overall impedance rise of the cathode and contribute to the mechanism of lithium-ion cell failure.
Date: October 1, 2004
Creator: Lei, Jinglei; McLarnon, Frank & Kostecki, Robert
Partner: UNT Libraries Government Documents Department

Nonperturbative theory of double photoionization of the hydrogen molecule

Description: We present completely ab initio nonperturbative calculations of the integral and single differential cross sections for double photoionization of H2 for photon energies from 53.9 to 75.7 eV. The method of exterior complex scaling, implemented with B-splines, is used to solve the Schrodinger equation for a correlated continuum wave function corresponding to a single photon having been absorbed by a correlated initial state. The results are in good agreement with experimental integral cross sections.
Date: October 1, 2004
Creator: Vanroose, W.; Martin, F.; Rescigno, T.N. & McCurdy, C.W.
Partner: UNT Libraries Government Documents Department

Corrective Action Investigation Plan for Corrective Action Unit 554: Area 23 Release Site, Nevada Test Site, Nevada, Rev. No.: 0

Description: This Corrective Action Investigation Plan (CAIP) contains project-specific information for conducting site investigation activities at Corrective Action Unit (CAU) 554: Area 23 Release Site, Nevada Test Site, Nevada. Information presented in this CAIP includes facility descriptions, environmental sample collection objectives, and criteria for the selection and evaluation of environmental samples. Corrective Action Unit 554 is located in Area 23 of the Nevada Test Site, which is 65 miles northwest of Las Vegas, Nevada. Corrective Action Unit 554 is comprised of one Corrective Action Site (CAS), which is: 23-02-08, USTs 23-115-1, 2, 3/Spill 530-90-002. This site consists of soil contamination resulting from a fuel release from underground storage tanks (USTs). Corrective Action Site 23-02-08 is being investigated because existing information on the nature and extent of potential contamination is insufficient to evaluate and recommend corrective action alternatives. Additional information will be obtained by conducting a corrective action investigation prior to evaluating corrective action alternatives and selecting the appropriate corrective action for this CAS. The results of the field investigation will support a defensible evaluation of viable corrective action alternatives that will be presented in the Corrective Action Decision Document for CAU 554. Corrective Action Site 23-02-08 will be investigated based on the data quality objectives (DQOs) developed on July 15, 2004, by representatives of the Nevada Division of Environmental Protection; U.S. Department of Energy, National Nuclear Security Administration Nevada Site Office; and contractor personnel. The DQO process was used to identify and define the type, amount, and quality of data needed to develop and evaluate appropriate corrective actions for CAU 554.
Date: October 1, 2004
Creator: Strand, David A.
Partner: UNT Libraries Government Documents Department

Development of an Implementation Plan for Atmospheric Carbon Monitoring in California

Description: This report describes the design of atmospheric CO{sub 2} concentration measurements that, in combination with other measurements and models, would be used to quantify regionally distributed CO{sub 2} exchanges from California's terrestrial ecosystems and CO{sub 2} emissions from fossil fuel combustion. Using models of net ecosystem CO{sub 2} exchange (NEE), fossil fuel CO{sub 2} emissions, and regional meteorology, we predict CO{sub 2} concentration ''signals'' in the atmosphere. The predictions of NEE exhibit spatial and temporal variations that are controlled by land cover and climate. Fossil fuel CO{sub 2} emissions from metropolitan areas are the strongest localized sources of CO{sub 2} while weaker but spatially extensive fossil emissions are present throughout the Central Valley. We subdivide the CO{sub 2} sources into four components: NEE inside and outside CA, and fossil fuel CO{sub 2} inside and outside CA. Maps of predicted atmospheric CO{sub 2} concentration signals from these four sources largely mirror the instantaneous emissions near strong sources but plumes of CO{sub 2} enriched or depleted air are predicted to advect far from their sources. We then identify a baseline set of observing stations from existing and possible future sites that could be used to characterize in-state and out-of-state ecosystem and fossil fuel contributions to atmospheric CO{sub 2} concentrations. For each of the stations we calculate mean midday concentration signals with standard deviation for each month and source. We also calculate the covariance of the signal due to NEE inside CA with each of the other signals to quantify how much of the signal from NEE inside CA might be readily separable from the other signals. On the basis of these predictions, we identify new observing stations and a measurement protocol that, in combination with existing stations, would provide data to estimate NEE within CA. Although beyond the scope of this project, ...
Date: October 1, 2004
Creator: Fischer, Marc L.; Riley, William J. & Tonse, Shaheen
Partner: UNT Libraries Government Documents Department

Concentrations of Radionuclides and Trace Elements in Soils and Vegetation Around the DARHT Facility during 2004

Description: Samples of soil, sediment, and unwashed overstory and understory vegetation were collected at four locations around the Dual-Axis Radiographic Hydrodynamic Test (DARHT) facility at Los Alamos National Laboratory (LANL). All samples were analyzed for concentrations of {sup 3}H, {sup 137}Cs, {sup 90}Sr, {sup 238}Pu, {sup 239,240}Pu, {sup 241}Am, {sup 234}U, {sup 235}U, {sup 238}U, Ag, As, Ba, Be, Cd, Cr, Cu, Hg, Ni, Pb, Sb, Se, and Tl. These results, which represent five years since the start of operations, were compared with baseline statistical reference level (BSRL) data established over a four-year-long preoperational period prior to DARHT operations, and to LANL and U.S. Environmental Protection Agency Screening Action Levels (SALs). Most radionuclides and trace elements in soil, sediment, and vegetation were below BSRL values and those soils/sediments that were above BSRLs were far below SALs.
Date: October 1, 2004
Creator: Fresquez, P.R.
Partner: UNT Libraries Government Documents Department

Spatially resolved characterization of biogenic manganese oxideproduction within a bacterial biofilm

Description: Pseudomonas putida strain MnB1, a biofilm forming bacteria, was used as a model for the study of bacterial Mn oxidation in freshwater and soil environments. The oxidation of Mn{sub (aq)}{sup +2} by P. putida was characterized by spatially and temporally resolving the oxidation state of Mn in the presence of a bacterial biofilm using scanning transmission x-ray microscopy (STXM) combined with near edge x-ray absorption fine structure (NEXAFS) spectroscopy at the Mn-L{sub 2,3} absorption edges. Subsamples were collected from growth flasks containing 0.1 mM and 1 mM total Mn at 16, 24, 36 and 48 hours after inoculation. Immediately after collection, the unprocessed hydrated subsamples were imaged at 40 nm resolution. Manganese NEXAFS spectra were extracted from x-ray energy sequences of STXM images (stacks) and fit with linear combinations of well characterized reference spectra to obtain quantitative relative abundances of Mn(II), Mn(III) and Mn(IV). Careful consideration was given to uncertainty in the normalization of the reference spectra, choice of reference compounds, and chemical changes due to radiation damage. The STXM results confirm that Mn{sub (aq)}{sup +2} was removed from solution by P. putida and was concentrated as Mn(III) and Mn(IV) immediately adjacent to the bacterial cells. The Mn precipitates were completely enveloped by bacterial biofilm material. The distribution of Mn oxidation states was spatially heterogeneous within and between the clusters of bacterial cells. Scanning transmission x-ray microscopy is a promising tool to advance the study of hydrated interfaces between minerals and bacteria, particularly in cases where the structure of bacterial biofilms needs to be maintained.
Date: October 1, 2004
Creator: Toner, Brandy; Fakra, Sirine; Villalobos, Mario; Warwick, Tony & Sposito, Garrison
Partner: UNT Libraries Government Documents Department

Investigating the Molecular Mechanism of TSO1 Function in Arabidopsis cell division and meristem development

Description: Unlike animals, plants are constantly exposed to environmental mutagens including ultraviolet light and reactive oxygen species. Further, plant cells are totipotent with highly plastic developmental programs. An understanding of molecular mechanisms underlying the ability of plants to monitor and repair its DNA and to eliminate damaged cells are of great importance. Previously we have identified two genes, TSO1 and TSO2, from a flowering plant Arabidopsis thaliana. Mutations in these two genes cause callus-like flowers, fasciated shoot apical meristems, and abnormal cell division, indicating that TSO1 and TSO2 may encode important cell cycle regulators. Previous funding from DOE led to the molecular cloning of TSO1, which was shown to encode a novel nuclear protein with two CXC domains suspected to bind DNA. This DOE grant has allowed us to characterize and isolate TSO2 that encodes the small subunit of the ribonucleotide reductase (RNR). RNR comprises two large subunits (R1) an d two small subunits (R2), catalyzes a rate-limiting step in the production of deoxyribonucleotides needed for DNA replication and repair. Previous studies in yeast and mammals indicated that defective RNR often led to cell cycle arrest, growth retardation and p53-dependent apoptosis while abnormally elevated RNR activities led to higher mutation rates. Subsequently, we identified two additional R2 genes, R2A and R2B in the Arabidopsis genome. Using reverse genetics, mutations in R2A and R2B were isolated, and double and triple mutants among the three R2 genes (TSO2, R2A and R2B) were constructed and analyzed. We showed that Arabidopsis tso2 mutants, with reduced dNTP levels, were more sensitive to UV-C. While r2a or r2b single mutants did not exhibit any phenotypes, tso2 r2b double mutants were embryonic lethal and tso2 r2a double mutants were seedling lethal indicating redundant functions among the three R2 genes. Furthermore, tso2 r2a double mutants exhibited increased DNA dam ...
Date: October 1, 2004
Creator: Liu, Zhongchi
Partner: UNT Libraries Government Documents Department

Cancer and aging: The importance of telomeres in genome maintenance

Description: Telomeres are the specialized DNA-protein structures that cap the ends of linear chromosomes, thereby protecting them from degradation and fusion by cellular DNA repair processes. In vertebrate cells, telomeres consist of several kilobase pairs of DNA having the sequence TTAGGG, a few hundred base pairs of single-stranded DNA at the 3' end of the telomeric DNA tract, and a host of proteins that organize the telomeric double and single stranded DNA into a protective structure. Functional telomeres are essential for maintaining the integrity and stability of genomes. When combined with loss of cell cycle checkpoint controls, telomere dysfunction can lead to genomic instability, a common cause and hallmark of cancer. Consequently, normal mammalian cells respond to dysfunctional telomeres by undergoing apoptosis (programmed cell death) or cellular senescence (permanent cell cycle arrest), two cellular tumor suppressor mechanisms. These tumor suppressor mechanisms are potent suppressors of cancer, but recent evidence suggests that they can antagonistically also contribute to aging phenotypes. Here, we review what is known about the structure and function of telomeres in mammalian cells, particularly human cells, and how telomere dysfunction may arise and contribute to cancer and aging phenotypes.
Date: October 1, 2004
Creator: Rodier, Francis; Kim, Sahn-ho; Nijjar, Tarlochan; Yaswen, Paul & Campisi, Judith
Partner: UNT Libraries Government Documents Department

OCRWM Science & Technology Program Corrosion Targeted Thrust

Description: The materials used for isolating waste in the proposed repository are an important component of the overall approach to the design of the repository system. Opportunities exist to enhance the understanding of material corrosion performance and to probe technical enhancements. These enhancements may include optimizing the performance of waste packages for increased reliability and cost effectiveness. Determination of the status and future performance of waste packages based upon materials, design and realistic repository conditions are important to guide rational, reliable and cost effective decisions by policy-makers, managers and engineers.
Date: October 1, 2004
Creator: DOE, U.S.
Partner: UNT Libraries Government Documents Department

2nd International Conference on Pathways, Networks, and Systems: Theory and Experiments

Description: With the availability of whole genome sequences, research attention shifts from gene sequences and genome content to protein functions and systems biology. Genes comprise a major component of the ''parts list'' that is required for building and maintaining of living organisms. Genome DNA sequences reveal the genetic inventory for a rapidly increasing number of species. Defining and interpreting the instruction manual for protein functions, individually and collectively, is the emerging challenge. Defining protein functions is a complex problem because each gene typically encodes several distinct proteins. As a result, the protein inventory includes as many as 100,000 distinct proteins. Protein functions can vary with developmental stage, anatomical location, and environmental context. Like the problem of sequencing the human genome, the multidimensional nature of protein functions in time, space and context constitutes one of the ''big'' problems in biomedical research. Resolving this problem is key to revolutionizing health care where a deep understanding of complex biological systems will lead to more powerful and specific ways to treat, and perhaps, even prevent birth defects and adult diseases. The meeting addressed the above issues.
Date: October 1, 2004
Creator: Aegean Conferences
Partner: UNT Libraries Government Documents Department

Distributed energy resources at naval base ventura county building 1512

Description: This paper reports the findings of a preliminary assessment of the cost effectiveness of distributed energy resources at Naval Base Ventura County (NBVC) Building 1512. This study was conducted in response to the base's request for design assistance to the Federal Energy Management Program. Given the current tariff structure there are two main decisions facing NBVC: whether to install distributed energy resources (DER), or whether to continue the direct access energy supply contract. At the current effective rate, given assumptions about the performance and structure of building energy loads and available generating technology characteristics, the results of this study indicate that if the building installed a 600 kW DER system with absorption cooling and heat capabilities chosen by cost minimization, the energy cost savings would be about 14 percent, or $55,000 per year. However, under current conditions, this study also suggests that significant savings could be obtained if Building 1 512 changed from the direct access contract to a SCE TOU-8 (Southern California Edison time of use tariff number 8) rate without installing a DER system. At current SCE TOU-8 tariffs, the potential savings from installation of a DER system would be about 4 percent, or $15,000 per year.
Date: October 1, 2004
Creator: Bailey, Owen C. & Marnay, Chris
Partner: UNT Libraries Government Documents Department

Corrective Action Investigation Plan for Corrective Action Unit 554: Area 23 Release Site, Nevada Test Site, Nevada, Rev. 0 with ROTC No. 1 and ROTC No. 2

Description: This Corrective Action Investigation Plan (CAIP) contains project-specific information for conducting site investigation activities at Corrective Action Unit (CAU) 554: Area 23 Release Site, Nevada Test Site, Nevada. Information presented in this CAIP includes facility descriptions, environmental sample collection objectives, and criteria for the selection and evaluation of environmental samples. Corrective Action Unit 554 is located in Area 23 of the Nevada Test Site, which is 65 miles northwest of Las Vegas, Nevada. Corrective Action Unit 554 is comprised of one Corrective Action Site (CAS), which is: 23-02-08, USTs 23-115-1, 2, 3/Spill 530-90-002. This site consists of soil contamination resulting from a fuel release from underground storage tanks (USTs). Corrective Action Site 23-02-08 is being investigated because existing information on the nature and extent of potential contamination is insufficient to evaluate and recommend corrective action alternatives. Additional information will be obtained by conducting a corrective action investigation prior to evaluating corrective action alternatives and selecting the appropriate corrective action for this CAS. The results of the field investigation will support a defensible evaluation of viable corrective action alternatives that will be presented in the Corrective Action Decision Document for CAU 554. Corrective Action Site 23-02-08 will be investigated based on the data quality objectives (DQOs) developed on July 15, 2004, by representatives of the Nevada Division of Environmental Protection; U.S. Department of Energy, National Nuclear Security Administration Nevada Site Office; and contractor personnel. The DQO process was used to identify and define the type, amount, and quality of data needed to develop and evaluate appropriate corrective actions for CAU 554. Appendix A provides a detailed discussion of the DQO methodology and the DQOs specific to CAS 23-02-08. The scope of the corrective action investigation for CAU 554 includes the following activities: (1) Move surface debris and/or materials, as needed, to ...
Date: October 1, 2004
Creator: Boehlecke, Robert F.
Partner: UNT Libraries Government Documents Department

ADVANCES IN COMPREHENSIVE GYROKINETIC SIMULATIONS OF TRANSPORT IN TOKAMAKS

Description: A continuum global gyrokinetic code GYRO has been developed to comprehensively simulate core turbulent transport in actual experimental profiles and enable direct quantitative comparisons to the experimental transport flows. GYRO not only treats the now standard ion temperature gradient (ITG) mode turbulence, but also treats trapped and passing electrons with collisions and finite {beta}, equilibrium ExB shear stabilization, and all in real tokamak geometry. Most importantly the code operates at finite relative gyroradius ({rho}{sub *}) so as to treat the profile shear stabilization and nonlocal effects which can break gyroBohm scaling. The code operates in either a cyclic flux-tube limit (which allows only gyroBohm scaling) or a globally with physical profile variation. Rohm scaling of DIII-D L-mode has been simulated with power flows matching experiment within error bars on the ion temperature gradient. Mechanisms for broken gyroBohm scaling, neoclassical ion flows embedded in turbulence, turbulent dynamos and profile corrugations, plasma pinches and impurity flow, and simulations at fixed flow rather than fixed gradient are illustrated and discussed.
Date: October 1, 2004
Creator: RE, WALTZ; J, CANDY; FL, HINTON; C, ESTRADA-MILA & JE, KINSEY
Partner: UNT Libraries Government Documents Department

Clad Degradation- Summary and Abstraction for LA

Description: The purpose of this model report is to develop the summary cladding degradation abstraction that will be used in the Total System Performance Assessment for the License Application (TSPA-LA). Most civilian commercial nuclear fuel is encased in Zircaloy cladding. The model addressed in this report is intended to describe the postulated condition of commercial Zircaloy-clad fuel as a function of postclosure time after it is placed in the repository. Earlier total system performance assessments analyzed the waste form as exposed UO{sub 2}, which was available for degradation at the intrinsic dissolution rate. Water in the waste package quickly became saturated with many of the radionuclides, limiting their release rate. In the total system performance assessments for the Viability Assessment and the Site Recommendation, cladding was analyzed as part of the waste form, limiting the amount of fuel available at any time for degradation. The current model is divided into two stages. The first considers predisposal rod failures (most of which occur during reactor operation and associated activities) and postdisposal mechanical failure (from static loading of rocks) as mechanisms for perforating the cladding. Other fuel failure mechanisms including those caused by handling or transportation have been screened out (excluded) or are treated elsewhere. All stainless-steel-clad fuel, which makes up a small percentage of the overall amount of fuel to be stored, is modeled as failed upon placement in the waste packages. The second stage of the degradation model is the splitting of the cladding from the reaction of water or moist air and UO{sub 2}. The splitting has been observed to be rapid in comparison to the total system performance assessment time steps and is modeled to be instantaneous. After the cladding splits, the rind buildup inside the cladding widens the split, increasing the diffusion area from the fuel rind to ...
Date: October 1, 2004
Creator: Stahl, D.
Partner: UNT Libraries Government Documents Department

Thermodynamics of Hydrogen Production from Dimethyl Ether Steam Reforming and Hydrolysis

Description: The thermodynamic analyses of producing a hydrogen-rich fuel-cell feed from the process of dimethyl ether (DME) steam reforming were investigated as a function of steam-to-carbon ratio (0-4), temperature (100 C-600 C), pressure (1-5 atm), and product species: acetylene, ethanol, methanol, ethylene, methyl-ethyl ether, formaldehyde, formic acid, acetone, n-propanol, ethane and isopropyl alcohol. Results of the thermodynamic processing of dimethyl ether with steam indicate the complete conversion of dimethyl ether to hydrogen, carbon monoxide and carbon dioxide for temperatures greater than 200 C and steam-to-carbon ratios greater than 1.25 at atmospheric pressure (P = 1 atm). Increasing the operating pressure was observed to shift the equilibrium toward the reactants; increasing the pressure from 1 atm to 5 atm decreased the conversion of dimethyl ether from 99.5% to 76.2%. The order of thermodynamically stable products in decreasing mole fraction was methane, ethane, isopropyl alcohol, acetone, n-propanol, ethylene, ethanol, methyl-ethyl ether and methanol--formaldehyde, formic acid, and acetylene were not observed. The optimal processing conditions for dimethyl ether steam reforming occurred at a steam-to-carbon ratio of 1.5, a pressure of 1 atm, and a temperature of 200 C. Modeling the thermodynamics of dimethyl ether hydrolysis (with methanol as the only product considered), the equilibrium conversion of dimethyl ether is limited. The equilibrium conversion was observed to increase with temperature and steam-to-carbon ratio, resulting in a maximum dimethyl ether conversion of approximately 68% at a steam-to-carbon ratio of 4.5 and a processing temperature of 600 C. Thermodynamically, dimethyl ether processed with steam can produce hydrogen-rich fuel-cell feeds--with hydrogen concentrations exceeding 70%. This substantiates dimethyl ether as a viable source of hydrogen for PEM fuel cells.
Date: October 1, 2004
Creator: Semelsberger, T.A.
Partner: UNT Libraries Government Documents Department

Transcriptional Regulation of Apolipoprotein A5 Gene Expression by the Nuclear Receptor ROR alpha

Description: Apolipoprotein A5 has recently been identified as a crucial determinant of plasma triglyceride levels. Our results showed that RORa up-regulates human APOA5 but has no effect on mouse apoa5 promoter. These data suggest an additional important physiological role for RORa in the regulation of genes involved in plasma triglyceride homeostasis in human and probably in the development of atherosclerosis
Date: October 1, 2004
Creator: Genoux, Annelise; Dehondt, Helene; Helleboid-Chapman, Audrey; Duhem, Christian; Hum, Dean W.; Martin, Genevieve et al.
Partner: UNT Libraries Government Documents Department

Thermal Analysis of Simulated Slurry Mix Evaporator Samples

Description: This report documents the results of applying thermal analysis methods to the characterization of the properties of Slurry Mix Evaporator (SME) product samples as a function of temperature. The goal of the research program was to determine if various thermal analysis methods could aid in measuring melter feed melt rate, study the impact of post SME additions of formic acid, and aid in developing a better understanding of melter cold cap chemistry. The thermal analysis methods tested in this program included Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis (TGA), and Accelerating Rate Calorimetry (ARC). The samples used in the study were from a study on the impact of acid stoichiometry and redox on melt rate.
Date: October 1, 2004
Creator: RUSSELL, EIBLING
Partner: UNT Libraries Government Documents Department

ADVANCES IN COMPREHENSIVE GYROKINETIC SIMULATIONS OF TRANSPORT IN TOKAMAKS

Description: A continuum global gyrokinetic code GYRO has been developed to comprehensively simulate core turbulent transport in actual experimental profiles and enable direct quantitative comparisons to the experimental transport flows. GYRO not only treats the now standard ion temperature gradient (ITG) mode turbulence, but also treats trapped and passing electrons with collisions and finite {beta}, equilibrium ExB shear stabilization, and all in real tokamak geometry. Most importantly the code operates at finite relative gyroradius ({rho}{sub *}) so as to treat the profile shear stabilization and nonlocal effects which can break gyroBohm scaling. The code operates in either a cyclic flux-tube limit (which allows only gyroBohm scaling) or globally with physical profile variation. Bohm scaling of DIII-D L-mode has been simulated with power flows matching experiment within error bars on the ion temperature gradient. Mechanisms for broken gyroBohm scaling, neoclassical ion flows embedded in turbulence, turbulent dynamos and profile corrugations, are illustrated.
Date: October 1, 2004
Creator: WALTZ,R.E; CANDY,J; HINTON,F.L; ESTRADA-MILA,C & KINSEY,J.E
Partner: UNT Libraries Government Documents Department

Radiation from laser accelerated electron bunches: Coherent terahertz and femtosecond X-rays

Description: Electron beam based radiation sources provide electromagnetic radiation for countless applications. The properties of the radiation are primarily determined by the properties of the electron beam. Compact laser driven accelerators are being developed that can provide ultra-short electron bunches (femtosecond duration) with relativistic energies reaching towards a GeV. The electron bunches are produced when an intense laser interacts with a dense plasma and excites a large amplitude plasma density modulation (wakefield) that can trap background electrons and accelerate them to high energies. The short pulse nature of the accelerated bunches and high particle energy offer the possibility of generating radiation from one compact source that ranges from coherent terahertz to gamma rays. The intrinsic synchronization to a laser pulse and unique character of the radiation offers a wide range of possibilities for scientific applications. Two particular radiation source regimes are discussed: Coherent terahertz emission and x-ray emission based on betatron oscillations and Thomson scattering.
Date: October 1, 2004
Creator: Leemans, W.P.; Esarey, E.; van Tilborg, J.; Michel, P.A.; Schroeder, C.B.; Toth, Cs. et al.
Partner: UNT Libraries Government Documents Department

Top quark and higgs physics at the tevatron

Description: This is a writeup of my lectures given at the International Workshop on Frontiers of High Energy Physics, held at CCAST, Beijing, China during July 2-10. I discuss some basic experimental techniques for studying the Top quark and Higgsboson at the Tevatron, and review some recent results from CDF and D0 and their future prospects.
Date: October 1, 2004
Creator: Yao, WeiMing
Partner: UNT Libraries Government Documents Department

An overview of alternative fossil fuel price and carbon regulation scenarios

Description: The benefits of the Department of Energy's research and development (R&D) efforts have historically been estimated under business-as-usual market and policy conditions. In recognition of the insurance value of R&D, however, the Office of Energy Efficiency and Renewable Energy (EERE) and the Office of Fossil Energy (FE) have been exploring options for evaluating the benefits of their R&D programs under an array of alternative futures. More specifically, an FE-EERE Scenarios Working Group (the Working Group) has proposed to EERE and FE staff the application of an initial set of three scenarios for use in the Working Group's upcoming analyses: (1) a Reference Case Scenario, (2) a High Fuel Price Scenario, which includes heightened natural gas and oil prices, and (3) a Carbon Cap-and-Trade Scenario. The immediate goal is to use these scenarios to conduct a pilot analysis of the benefits of EERE and FE R&D efforts. In this report, the two alternative scenarios being considered by EERE and FE staff--carbon cap-and-trade and high fuel prices--are compared to other scenarios used by energy analysts and utility planners. The report also briefly evaluates the past accuracy of fossil fuel price forecasts. We find that the natural gas prices through 2025 proposed in the FE-EERE Scenarios Working Group's High Fuel Price Scenario appear to be reasonable based on current natural gas prices and other externally generated gas price forecasts and scenarios. If anything, an even more extreme gas price scenario might be considered. The price escalation from 2025 to 2050 within the proposed High Fuel Price Scenario is harder to evaluate, primarily because few existing forecasts or scenarios extend beyond 2025, but, at first blush, it also appears reasonable. Similarly, we find that the oil prices originally proposed by the Working Group in the High Fuel Price Scenario appear to be reasonable, if ...
Date: October 1, 2004
Creator: Wiser, Ryan & Bolinger, Mark
Partner: UNT Libraries Government Documents Department

Efficacy of intermittent ventilation for providing acceptable indoor air quality

Description: Ventilation standards and guidelines typically treat ventilation as a constant and specify its value. In many circumstances a designer wishes to use intermittent ventilation, rather than constant ventilation, but there are no easy equivalencies available. This report develops a model of efficacy that allows one to calculate how much intermittent ventilation one needs to get the same indoor air quality as a the continuous value specified. We have found that there is a simple relationship between three dimensionless quantities: the temporal ventilation effectiveness (which we call the efficacy), the nominal turn-over and the under-ventilation fraction. This relationship allows the calculation of intermittent ventilation for a wide variety of parameters and conditions. We can use the relationship to define a critical time that separates the regime in which ventilation variations can be averaged over from the regime in which variable ventilation is of low effectiveness. We have found that ventilation load-shifting, temporary protection against poor outdoor air quality and dynamic ventilation strategies can be quite effective in low-density buildings such as single-family houses or office spaces. The results of this work enable ventilation standards and guidelines to allow this extra flexibility and still provide acceptable indoor air quality.
Date: October 1, 2004
Creator: Sherman, M.H.
Partner: UNT Libraries Government Documents Department

Houses need to breathe--right?

Description: Houses need to breathe, but we can no longer leave the important functions associated with ventilation to be met accidentally. A designed ventilation system must be considered as much a part of a home as its heating system. Windows are a key part of that system because they allow a quick increase in ventilation for unusual events, but neither they nor a leaky building shell can be counted on to provide minimum levels.
Date: October 1, 2004
Creator: Sherman, Max H.
Partner: UNT Libraries Government Documents Department