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The Diaries of John Gregory Bourke: Volume 4, July 3, 1880-May 22, 1881

Access: Use of this item is restricted to the UNT Community
John Gregory Bourke kept a monumental set of diaries beginning as a young cavalry lieutenant in Arizona in 1872, and ending the evening before his death in 1896. As aide-de-camp to Brigadier General George Crook, he had an insider's view of the early Apache campaigns, the Great Sioux War, the Cheyenne Outbreak, and the Geronimo War. Bourke's writings reveal much about military life on the western frontier, but he also was a noted ethnologist, writing extensive descriptions of American Indian civilization and illustrating his diaries with sketches and photographs. Previously, researchers could consult only a small part of Bourke’s diary material in various publications, or else take a research trip to the archive and microfilm housed at West Point. Now, for the first time, the 124 manuscript volumes of the Bourke diaries are being compiled, edited, and annotated by Charles M. Robinson III, in a planned set of eight books easily accessible to the modern researcher. Volume 4 chronicles the political and managerial affairs in Crook’s Department of the Platte. A large portion centers on the continuing controversy concerning the forced relocation of the Ponca Indians from their ancient homeland along the Dakota-Nebraska line to a new reservation in the …
Date: May 15, 2009
Creator: Bourke, John Gregory
Object Type: Book
System: The UNT Digital Library
Military Housing Privatization: DOD Faces New Challenges Due to Significant Growth at Some Installations and Recent Turmoil in the Financial Markets (open access)

Military Housing Privatization: DOD Faces New Challenges Due to Significant Growth at Some Installations and Recent Turmoil in the Financial Markets

A letter report issued by the Government Accountability Office with an abstract that begins "In response to challenges the Department of Defense (DOD) was facing to repair, renovate, and construct military family housing, Congress enacted the Military Housing Privatization Initiative in 1996. The initiative enables DOD to leverage private sector resources to construct or renovate family housing. As of March 2009, DOD had awarded 94 projects and attracted over $22 billion in private financing. DOD plans to privatize 98 percent of its domestic family housing through 2012. Since GAO's last housing privatization report in 2006, major force structure initiatives have placed new demands on DOD for housing. GAO was asked to assess (1) the progress of DOD's housing privatization program, (2) the occupancy rates of the housing projects, (3) the impact of various force structure initiatives and DOD's efforts to mitigate any challenges, and (4) the effect of financial market turmoil on some projects. To perform this work, GAO visited 13 installations with privatization projects; analyzed project performance data; and interviewed DOD officials, real estate consultants, and private developers."
Date: May 15, 2009
Creator: United States. Government Accountability Office.
Object Type: Report
System: The UNT Digital Library
Financial Audit: Congressional Award Foundation's Fiscal Years 2008 and 2007 Financial Statements (open access)

Financial Audit: Congressional Award Foundation's Fiscal Years 2008 and 2007 Financial Statements

A letter report issued by the Government Accountability Office with an abstract that begins "This report presents our opinion on the financial statements of the Congressional Award Foundation (the Foundation) for the fiscal years ended September 30, 2008, and 2007. These financial statements are the responsibility of the Foundation. This report also presents (1) our opinion on the effectiveness of the Foundation's related internal control as of September 30, 2008, and (2) the results of our tests of the Foundation's compliance during fiscal year 2008 with selected provisions of laws and regulations. We conducted our audit pursuant to section 107 of the Congressional Award Act, as amended (2 U.S.C. 807), and in accordance with U.S. generally accepted government auditing standards."
Date: May 15, 2009
Creator: United States. Government Accountability Office.
Object Type: Report
System: The UNT Digital Library
Organized Crime in the United States: Trends and Issues for Congress (open access)

Organized Crime in the United States: Trends and Issues for Congress

This report discusses the threat of organized crime against the United States, most notably organized crime from criminal organizations in Russia, Asia, Italy, the Balkans, the Middle East, and Africa. The report explores the issue of organized crime in relation to the economic downturn and national security, namely terrorism. The report also discusses how Congress is currently working to address these issues and includes information on relevant pieces of legislation.
Date: May 15, 2009
Creator: Finklea, Kristin M.
Object Type: Report
System: The UNT Digital Library
Greensheet (Houston, Tex.), Vol. 40, No. 178, Ed. 1 Friday, May 15, 2009 (open access)

Greensheet (Houston, Tex.), Vol. 40, No. 178, Ed. 1 Friday, May 15, 2009

Free weekly newspaper that includes business and classified advertising.
Date: May 15, 2009
Creator: unknown
Object Type: Newspaper
System: The Portal to Texas History
Dallas Voice (Dallas, Tex.), Vol. 25, No. 52, Ed. 1 Friday, May 15, 2009 (open access)

Dallas Voice (Dallas, Tex.), Vol. 25, No. 52, Ed. 1 Friday, May 15, 2009

Weekly newspaper from Dallas, Texas that includes local, state, and national news and advertising of interest to the Lesbian, Gay, Bisexual, and Transgender (LGBT) community.
Date: May 15, 2009
Creator: Nash, Tammye
Object Type: Newspaper
System: The UNT Digital Library
Fermi/LAT Discovery of Gamma-Ray Emission From the Flat-Spectrum Radio Quasar PKS 1454-354 (open access)

Fermi/LAT Discovery of Gamma-Ray Emission From the Flat-Spectrum Radio Quasar PKS 1454-354

None
Date: May 15, 2009
Creator: Abdo, Aous A.; Ackermann, M.; Atwood, W. B.; Axelsson, M.; Baldini, L.; Ballet, J. et al.
Object Type: Article
System: The UNT Digital Library
Discovery of Pulsed Gamma Rays from the Young Radio Pulsar PSR J1028-5819 with the Fermi Large Area Telescope (open access)

Discovery of Pulsed Gamma Rays from the Young Radio Pulsar PSR J1028-5819 with the Fermi Large Area Telescope

Radio pulsar PSR J1028-5819 was recently discovered in a high-frequency search (at 3.1 GHz) in the error circle of the Energetic Gamma-Ray Experiment Telescope (EGRET) source 3EG J1027-5817. The spin-down power of this young pulsar is great enough to make it very likely the counterpart for the EGRET source. We report here the discovery of {gamma}-ray pulsations from PSR J1028-5819 in early observations by the Large Area Telescope (LAT) on the Fermi Gamma-Ray Space Telescope. The {gamma}-ray light curve shows two sharp peaks having phase separation of 0.460 {+-} 0.004, trailing the very narrow radio pulse by 0.200 {+-} 0.003 in phase, very similar to that of other known {gamma}-ray pulsars. The measured {gamma}-ray flux gives an efficiency for the pulsar of {approx}10-20% (for outer magnetosphere beam models). No evidence of a surrounding pulsar wind nebula is seen in the current Fermi data but limits on associated emission are weak because the source lies in a crowded region with high background emission. However, the improved angular resolution afforded by the LAT enables the disentanglement of the previous COS-B and EGRET source detections into at least two distinct sources, one of which is now identified as PSR J1028-5819.
Date: May 15, 2009
Creator: Abdo, Aous A.; Ackermann, M.; Atwood, W.B.; Baldini, L.; Ballet, J.; Barbiellini, Guido et al.
Object Type: Article
System: The UNT Digital Library
Greensheet (Houston, Tex.), Vol. 40, No. 179, Ed. 1 Friday, May 15, 2009 (open access)

Greensheet (Houston, Tex.), Vol. 40, No. 179, Ed. 1 Friday, May 15, 2009

Free weekly newspaper that includes business and classified advertising.
Date: May 15, 2009
Creator: unknown
Object Type: Newspaper
System: The Portal to Texas History
Sampling Artifacts from Conductive Silicone Tubing (open access)

Sampling Artifacts from Conductive Silicone Tubing

We report evidence that carbon impregnated conductive silicone tubing used in aerosol sampling systems can introduce two types of experimental artifacts: 1) silicon tubing dynamically absorbs carbon dioxide gas, requiring greater than 5 minutes to reach equilibrium and 2) silicone tubing emits organic contaminants containing siloxane that adsorb onto particles traveling through it and onto downstream quartz fiber filters. The consequence can be substantial for engine exhaust measurements as both artifacts directly impact calculations of particulate mass-based emission indices. The emission of contaminants from the silicone tubing can result in overestimation of organic particle mass concentrations based on real-time aerosol mass spectrometry and the off-line thermal analysis of quartz filters. The adsorption of siloxane contaminants can affect the surface properties of aerosol particles; we observed a marked reduction in the water-affinity of soot particles passed through conductive silicone tubing. These combined observations suggest that the silicone tubing artifacts may have wide consequence for the aerosol community and should, therefore, be used with caution. Gentle heating, physical and chemical properties of the particle carriers, exposure to solvents, and tubing age may influence siloxane uptake. The amount of contamination is expected to increase as the tubing surface area increases and as the …
Date: May 15, 2009
Creator: Timko, Michael T.; Yu, Zhenhong; Kroll, Jesse; Jayne, John T.; Worsnop, Douglas R.; Miake-Lye, Richard C. et al.
Object Type: Article
System: The UNT Digital Library
Optics Design for a Soft X-ray FEL at the SLAC A-Line (open access)

Optics Design for a Soft X-ray FEL at the SLAC A-Line

LCLS capabilities can be significantly extended with a second undulator aiming at the soft x-ray spectrum (1-5 nm). To allow for simultaneous hard and soft x-ray operations, 14 GeV beams at the end of the LCLS accelerator can be intermittently switched into the SLAC A-line (the beam transport line to End Station A) where the second undulator may be located. In this paper, we discuss the A-line optics design for transporting the high-brightness LCLS beams using the existing tunnel. To preserve the high brightness of the LCLS beams, special attention is paid to effects of incoherent and coherent synchrotron radiation. Start-to-end simulations using realistic LCLS beam distributions are carried out.
Date: May 15, 2009
Creator: Geng, H; Ding, Y.; Emma, P.; Huang, Z.; Nosochkov, Y. & Woodley, M.
Object Type: Article
System: The UNT Digital Library
Historic Habitat Opportunities and Food-Web Linkages of Juvenile Salmon in the Columbia River Estuary, Annual Report of Research. (open access)

Historic Habitat Opportunities and Food-Web Linkages of Juvenile Salmon in the Columbia River Estuary, Annual Report of Research.

In 2002 with support from the U.S. Army Corps of Engineers (USACE), an interagency research team began investigating salmon life histories and habitat use in the lower Columbia River estuary to fill significant data gaps about the estuary's potential role in salmon decline and recovery . The Bonneville Power Administration (BPA) provided additional funding in 2004 to reconstruct historical changes in estuarine habitat opportunities and food web linkages of Columbia River salmon (Onchorhynchus spp.). Together these studies constitute the estuary's first comprehensive investigation of shallow-water habitats, including selected emergent, forested, and scrub-shrub wetlands. Among other findings, this research documented the importance of wetlands as nursery areas for juvenile salmon; quantified historical changes in the amounts and distributions of diverse habitat types in the lower estuary; documented estuarine residence times, ranging from weeks to months for many juvenile Chinook salmon (O. tshawytscha); and provided new evidence that contemporary salmonid food webs are supported disproportionately by wetland-derived prey resources. The results of these lower-estuary investigations also raised many new questions about habitat functions, historical habitat distributions, and salmon life histories in other areas of the Columbia River estuary that have not been adequately investigated. For example, quantitative estimates of historical habitat changes …
Date: May 15, 2009
Creator: Bottom, Daniel L.; Simenstad, Charles A. & Campbell, Lance
Object Type: Report
System: The UNT Digital Library
Developmental roles of 21 Drosophila transcription factors are determined by quantitative differences in binding to an overlapping set of thousands of genomic regions (open access)

Developmental roles of 21 Drosophila transcription factors are determined by quantitative differences in binding to an overlapping set of thousands of genomic regions

BACKGROUND: We previously established that six sequence-specific transcription factors that initiate anterior/posterior patterning in Drosophila bind to overlapping sets of thousands of genomic regions in blastoderm embryos. While regions bound at high levels include known and probable functional targets, more poorly bound regions are preferentially associated with housekeeping genes and/or genes not transcribed in the blastoderm, and are frequently found in protein coding sequences or in less conserved non-coding DNA, suggesting that many are likely non-functional. RESULTS: Here we show that an additional 15 transcription factors that regulate other aspects of embryo patterning show a similar quantitative continuum of function and binding to thousands of genomic regions in vivo. Collectively, the 21 regulators show a surprisingly high overlap in the regions they bind given that they belong to 11 DNA binding domain families, specify distinct developmental fates, and can act via different cis-regulatory modules. We demonstrate, however, that quantitative differences in relative levels of binding to shared targets correlate with the known biological and transcriptional regulatory specificities of these factors. CONCLUSIONS: It is likely that the overlap in binding of biochemically and functionally unrelated transcription factors arises from the high concentrations of these proteins in nuclei, which, coupled with their …
Date: May 15, 2009
Creator: MacArthur, Stewart; Li, Xiao-Yong; Li, Jingyi; Brown, James B.; Chu, Hou Cheng; Zeng, Lucy et al.
Object Type: Article
System: The UNT Digital Library
Emissions of trace gases and aerosols during the open combustion of biomass in the laboratory (open access)

Emissions of trace gases and aerosols during the open combustion of biomass in the laboratory

We characterized the gas- and speciated aerosol-phase emissions from the open combustion of 33 different plant species during a series of 255 controlled laboratory burns during the Fire Laboratory at Missoula Experiments (FLAME). The plant species we tested were chosen to improve the existing database for U.S. domestic fuels: laboratory-based emission factors have not previously been reported for many commonly-burned species that are frequently consumed by fires near populated regions and protected scenic areas. The plants we tested included the chaparral species chamise, manzanita, and ceanothus, and species common to the southeastern US (common reed, hickory, kudzu, needlegrass rush, rhododendron, cord grass, sawgrass, titi, and wax myrtle). Fire-integrated emission factors for gas-phase CO{sub 2}, CO, CH{sub 4}, C{sub 2-4} hydrocarbons, NH{sub 3}, SO{sub 2}, NO, NO{sub 2}, HNO{sub 3} and particle-phase organic carbon (OC), elemental carbon (EC), SO{sub 4}{sup 2-}, NO{sub 3}{sup -}, Cl{sup -}, Na{sup +}, K{sup +}, and NH{sub 4}{sup +} generally varied with both fuel type and with the fire-integrated modified combustion efficiency (MCE), a measure of the relative importance of flaming- and smoldering-phase combustion to the total emissions during the burn. Chaparral fuels tended to emit less particulate OC per unit mass of dry fuel than …
Date: May 15, 2009
Creator: McMeeking, Gavin R.; Kreidenweis, Sonia M.; Baker, Stephen; Carrico, Christian M.; Chow, Judith C.; Collett, Jr., Jeffrey L. et al.
Object Type: Article
System: The UNT Digital Library
Functional Analysis of Shewanella, a cross genome comparison. (open access)

Functional Analysis of Shewanella, a cross genome comparison.

The bacterial genus Shewanella includes a group of highly versatile organisms that have successfully adapted to life in many environments ranging from aquatic (fresh and marine) to sedimentary (lake and marine sediments, subsurface sediments, sea vent). A unique respiratory capability of the Shewanellas, initially observed for Shewanella oneidensis MR-1, is the ability to use metals and metalloids, including radioactive compounds, as electron acceptors. Members of the Shewanella genus have also been shown to degrade environmental pollutants i.e. halogenated compounds, making this group highly applicable for the DOE mission. S. oneidensis MR-1 has in addition been found to utilize a diverse set of nutrients and to have a large set of genes dedicated to regulation and to sensing of the environment. The sequencing of the S. oneidensis MR-1 genome facilitated experimental and bioinformatics analyses by a group of collaborating researchers, the Shewanella Federation. Through the joint effort and with support from Department of Energy S. oneidensis MR-1 has become a model organism of study. Our work has been a functional analysis of S. oneidensis MR-1, both by itself and as part of a comparative study. We have improved the annotation of gene products, assigned metabolic functions, and analyzed protein families present …
Date: May 15, 2009
Creator: Serres, Margrethe H.
Object Type: Report
System: The UNT Digital Library
Drought resilience of the California Central Valley surface-groundwater-conveyance system (open access)

Drought resilience of the California Central Valley surface-groundwater-conveyance system

A series of drought simulations were performed for the California Central Valley using computer applications developed by the California Department of Water Resources and historical datasets representing a range of droughts from mild to severe for time periods lasting up to 60 years. Land use, agricultural cropping patterns, and water demand were held fixed at the 2003 level and water supply was decreased by amounts ranging between 25 and 50%, representing light to severe drought types. Impacts were examined for four hydrologic subbasins, the Sacramento Basin, the San Joaquin Basin, the Tulare Basin, and the Eastside Drainage. Results suggest the greatest impacts are in the San Joaquin and Tulare Basins, regions that are heavily irrigated and are presently overdrafted in most years. Regional surface water diversions decrease by as much as 70%. Stream-to-aquifer flows and aquifer storage declines were proportional to drought severity. Most significant was the decline in ground water head for the severe drought cases, where results suggest that under these scenarios the water table is unlikely to recover within the 30-year model-simulated future. However, the overall response to such droughts is not as severe as anticipated and the Sacramento Basin may act as ground-water insurance to sustain …
Date: May 15, 2009
Creator: Miller, N. L.; Dale, L. L.; Brush, C.; Vicuna, S.; Kadir, T. N.; Dogrul, E. C. et al.
Object Type: Article
System: The UNT Digital Library
Radiation Chemistry 2008 Gordon Research Conference - July 6-11, 2008 (open access)

Radiation Chemistry 2008 Gordon Research Conference - July 6-11, 2008

Radiation Chemistry is chemistry initiated by ionizing radiation: i.e. photons or particles with energy sufficient to create charge pairs and/or free radicals in a medium. The important transients include conduction band electrons and 'holes', excitons, ionic and neutral free radicals, highly excited states, and solvated electrons. Effects of radiation span timescales from the energy deposition in femtoseconds, through geminate recombination in picoseconds and nanoseconds, to fast radical chemistry in microseconds and milliseconds, and ultimately to processes like cancer occurring decades later. The radiation sources used to study these processes likewise run from femtosecond lasers to nanosecond accelerators to years of gamma irradiation. As a result the conference has a strong interdisciplinary flavor ranging from fundamental physics to clinical biology. While the conference focuses on fundamental science, application areas highlighted in the present conference will include nuclear power, polymer processing, and extraterrestrial chemistry.
Date: May 15, 2009
Creator: Bartels, David M.
Object Type: Article
System: The UNT Digital Library
On Possible Interpretations of the High Energy Electron-Positron Spectrum Measured by the Fermi Large Area Telescope (open access)

On Possible Interpretations of the High Energy Electron-Positron Spectrum Measured by the Fermi Large Area Telescope

The Fermi-LAT experiment recently reported high precision measurements of the spectrum of cosmic-ray electrons-plus-positrons (CRE) between 20 GeV and 1 TeV. The spectrum shows no prominent spectral features, and is significantly harder than that inferred from several previous experiments. Here we discuss several interpretations of the Fermi results based either on a single large scale Galactic CRE component or by invoking additional electron-positron primary sources, e.g. nearby pulsars or particle Dark Matter annihilation. We show that while the reported Fermi-LAT data alone can be interpreted in terms of a single component scenario, when combined with other complementary experimental results, specifically the CRE spectrum measured by H.E.S.S. and especially the positron fraction reported by PAMELA between 1 and 100 GeV, that class of models fails to provide a consistent interpretation. Rather, we find that several combinations of parameters, involving both the pulsar and dark matter scenarios, allow a consistent description of those results. We also briefly discuss the possibility of discriminating between the pulsar and dark matter interpretations by looking for a possible anisotropy in the CRE flux.
Date: May 15, 2009
Creator: Grasso, D.; Profumo, S.; Strong, A.W.; Baldini, L.; Bellazzini, R.; Bloom, E.D. et al.
Object Type: Report
System: The UNT Digital Library
Observed 1970-2005 cooling of summer daytime temperatures in coastal California (open access)

Observed 1970-2005 cooling of summer daytime temperatures in coastal California

The study evaluated 1948-2004 summer (JJA) mean monthly air temperatures for two California air basins: SoCAB and SFBA. The study focuses on the more rapid post-1970 warming period, and its daily T{sub min} and T{sub max} values were used to produce average monthly values and spatial distributions of trends for each air basins. Additional analyses included T{sub D} values at two NWS sites, SSTs, NCEP reanalysis sea-level pressures, and GCM T{sub ave}-values. Results for all California COOP sites together showed increased JJA T{sub ave}-values; asymmetric warming, as T{sub min}-values increase faster than T{sub max}-values; and thus decreased DTR values. The spatial distribution of observed SoCAB and SFBA T{sub max} values exhibited a complex pattern, with cooling in low-elevation coastal-areas open to marine air penetration and warming at inland areas. Results also showed that decreased DTR values in the valleys arose from small increases at 'inland' sites combined with large decreases at 'coastal' sites. Previous studies suggest that cooling JJA T{sub max}-values in coastal California were due to increased irrigation, coastal upwelling, or cloud cover, while the current hypothesis is that they arises from GHG-induced global-warming of 'inland' areas, which results in increased sea breeze flow activity. Sea level pressure trends …
Date: May 15, 2009
Creator: Lebassi, B.; Gonzalez, J.; Fabris, D.; Maurer, E.; Miller, N.; Milesi, C. et al.
Object Type: Article
System: The UNT Digital Library
Longitudinal Bunch Position Control for the Super-B Accelerator (open access)

Longitudinal Bunch Position Control for the Super-B Accelerator

The use of normal conducting cavities and an ion-clearing gap will cause a significant RF accelerating voltage gap transient and longitudinal phase shift of the individual bunches along the bunch train in both rings of the SuperB accelerator. Small relative centroid position shifts between bunches of the colliding beams will have a large adverse impact on the luminosity due to the small {beta}*{sub y} at the interaction point (IP). We investigate the possibility of minimizing the relative longitudinal position shift between bunches by reducing the gap transient in each ring and matching the longitudinal bunch positions of the two rings at the IP using feedback/feedforward techniques in the LLRF. The analysis is conducted assuming maximum use of the klystron power installed in the system.
Date: May 15, 2009
Creator: Bertsche, Kirk; Rivetta, Claudio; Sullivam, Michael K. & Drago, Alessandro
Object Type: Article
System: The UNT Digital Library
Application of Non-Linear Time-Domain RF Simulations to Longitudinal Emittance Studies for the LHC (open access)

Application of Non-Linear Time-Domain RF Simulations to Longitudinal Emittance Studies for the LHC

A non-linear time-domain simulation has been developed that can determine technical limitations, effects of non-linearities and imperfections, and impact of additive noise on the interaction of the beam with the Impedance Control Radio Frequency (RF) systems [1]. We present a formalism for the extraction of parameters from the time domain simulation to determine the sensitivity of the beam longitudinal emittance and dilution on the RF system characteristics. Previous studies [2], [3] have estimated the effect of a noise source on the beam characteristics assuming an independent perturbation source of the RF voltage and a simplified beam model with no coupling. We present the methodology for the time-domain simulation study of the dependence of the accelerating voltage noise spectrum on the various RF parameters and the technical properties (such as non-linearities, thermal noise, frequency response etc.) of the Low Level RF (LLRF) system components. Future plans to expand this formalism to coupled bunch studies of longitudinal emittance growth in the LHC at nominal and upgraded beam currents are briefly summarized.
Date: May 15, 2009
Creator: Mastorides, T.; Rivetta, C.; Fox, J.D. & Winkle, D.Van
Object Type: Article
System: The UNT Digital Library
Investigations into Cost Reductions of X-band Instrumentation (open access)

Investigations into Cost Reductions of X-band Instrumentation

The prohibitive costs of commercial test equipment for making fast and accurate pulsed phase and amplitude measurements at X-Band result in decreased productivity due to shortages of shared equipment across the test laboratory. In addition, most current set-ups rely on the use of pulsed power heads which do not allow for the measurement of phase thereby limiting the flexibility of available measurements. In this paper, we investigate less expensive in-house designed instrumentation based upon commercial satellite down converters and widely available logarithmic detector amplifiers and phase detectors. The techniques are used to measure X-Band pulses with widths of 50 ns to 10's of usec. We expect a dynamic range of 30-40 dB with accuracies of better than +/- 0.1 dB and +/- 1 degree of phase. We show preliminary results of the built and tested modules. Block diagrams of the down conversion scheme, and the architecture of a multi-signal X-band RF monitor and measurement system is illustrated. Measured results, and possible modifications and upgrades are presented.
Date: May 15, 2009
Creator: Van Winkle, D.; Dolgashev, V. A.; Fox, J. D. & Tantawi, S. G.
Object Type: Article
System: The UNT Digital Library
Sensitivity analysis of ozone formation and transport for a Central California air pollution episode (open access)

Sensitivity analysis of ozone formation and transport for a Central California air pollution episode

CMAQ-HDDM is used to determine spatial and temporal variations in ozone limiting reagents and local vs upwind source contributions for an air pollution episode in Central California. We developed a first- and second- order sensitivity analysis approach with the Decoupled Direct Method to examine spatial and temporal variations of ozone-limiting reagents and the importance of local vs upwind emission sources in the San Joaquin Valley of central California for a five-day ozone episode (29th July-3rd Aug, 2000). Despite considerable spatial variations, nitrogen oxides (NO{sub x}) emission reductions are overall more effective than volatile organic compound (VOC) control for attaining the 8-hr ozone standard in this region for this episode, in contrast to the VOC control that works better for attaining the prior 1-hr ozone standard. Inter-basin source contributions of NO{sub x} emissions are limited to the northern part of the SJV, while anthropogenic VOC (AVOC) emissions, especially those emitted at night, influence ozone formation in the SJV further downwind. Among model input parameters studied here, uncertainties in emissions of NO{sub x} and AVOC, and the rate coefficient of the OH + NO{sub 2} termination reaction, have the greatest effect on first-order ozone responses to changes in NO{sub x} emissions. Uncertainties …
Date: May 15, 2009
Creator: Jin, Ling; Tonse, Shaheen; Cohan, Daniel S.; Mao, Xiaoling; Harley, Robert A. & Brown, Nancy J.
Object Type: Article
System: The UNT Digital Library
RADIATION STABILITY OF NAFION MEMBRANES USED FOR ISOTOPE SEPARATION BY PROTON EXCHANGE MEMBRANE ELECTROLYSIS (open access)

RADIATION STABILITY OF NAFION MEMBRANES USED FOR ISOTOPE SEPARATION BY PROTON EXCHANGE MEMBRANE ELECTROLYSIS

Proton Exchange Membrane Electrolyzers have potential interest for use for hydrogen isotope separation from water. In order for PEME to be fully utilized, more information is needed on the stability of Nafion when exposed to radiation. This work examines Nafion 117 under varying exposure conditions, including dose rate, total dosage and atmospheric condition. Analytical tools, such as FT-IR, ion exchange capacity, DMA and TIC-TOC were used to characterize the exposed membranes. Analysis of the water from saturated membranes can provide important data on the stability of the membranes during radiation exposure. It was found that the dose rate of exposure plays an important role in membrane degradation. Potential mechanisms for membrane degradation include peroxide formation by free radicals.
Date: May 15, 2009
Creator: Fox, E
Object Type: Article
System: The UNT Digital Library