Particulate matter chemistry and dynamics in the Twilight Zone at VERTIGO ALOHA and K2 Sites (open access)

Particulate matter chemistry and dynamics in the Twilight Zone at VERTIGO ALOHA and K2 Sites

Understanding particle dynamics in the 'Twilight Zone' is critical to prediction of the ocean's carbon cycle. As part of the VERTIGO (VERtical Transformations In the Global Ocean) project, this rarely sampled regime extending from the base of the euphotic layer to 1000 m, was characterized by double-paired day/night Multiple Unit Large Volume in-situ Filtration System (MULVFS) deployments and by {approx}100 high-frequency CTD/transmissometer/turbidity sensor profiles. VERTIGO studies lasting three weeks, contrasted oligotrophic station ALOHA (22.75{sup o}N 158{sup o}W), sampled in June-July 2004, with a biologically productive location (47{sup o}N 161{sup o}E) near station K2 in the Oyashio, occupied July-August 2005. Profiles of major and minor particulate components (C{sub org}, N, P, Ca, Si, Sr, Ba, Mn) in <1, 1-51, and >51 {micro}m size fractions, in-water optics, neutrally buoyant sediment trap (NBST) fluxes, and zooplankton data were intercompared. MULVFS total C{sub org} and C-Star particle beam attenuation coefficient (C{sub P}) were consistently related at both sites with a 27 {micro}M m{sup -1} conversion factor. 26 At K2, C{sub P} profiles further showed a multitude of transient spikes throughout the water column and spike abundance profiles closely paralleled the double peaked abundance profiles of zooplankton. Also at K2, copepods contributed {approx}40% and 10%, …
Date: March 25, 2008
Creator: Bishop, James K.B. & Wood, T.J.
Object Type: Article
System: The UNT Digital Library
Rapid Formation of Supermassive Black Hole Binaries in Galaxy Mergers with Gas (open access)

Rapid Formation of Supermassive Black Hole Binaries in Galaxy Mergers with Gas

Supermassive black holes (SMBHs) are a ubiquitous component of the nuclei of galaxies. It is normally assumed that, following the merger of two massive galaxies, a SMBH binary will form, shrink due to stellar or gas dynamical processes and ultimately coalesce by emitting a burst of gravitational waves. However, so far it has not been possible to show how two SMBHs bind during a galaxy merger with gas due to the difficulty of modeling a wide range of spatial scales. Here we report hydrodynamical simulations that track the formation of a SMBH binary down to scales of a few light years following the collision between two spiral galaxies. A massive, turbulent nuclear gaseous disk arises as a result of the galaxy merger. The black holes form an eccentric binary in the disk in less than a million years as a result of the gravitational drag from the gas rather than from the stars.
Date: March 24, 2008
Creator: Mayer, L.; Kazantzidis, S.; Madau, P.; Colpi, M.; Quinn, T. & Wadsley, J.
Object Type: Article
System: The UNT Digital Library
Post-Translational Modifications of Desulfovibrio vulgaris Hildenborough Sulfate Reduction Pathway Proteins (open access)

Post-Translational Modifications of Desulfovibrio vulgaris Hildenborough Sulfate Reduction Pathway Proteins

Recent developments in shotgun proteomics have enabled high-throughput studies of a variety of microorganisms at a proteome level and provide experimental validation for predicted open reading frames in the corresponding genome. More importantly, advances in mass spectrometric data analysis now allow mining of large proteomics data sets for the presence of post-translational modifications(PTMs). Although PTMs are a critical aspectof cellular activity, such information eludes cell-wide studies conducted at the transcript level. Here, we analyze several mass spectrometric data sets acquired using two-dimensional liquid chromatography tandem mass spectrometry, 2D-LC/MS/MS, for the sulfate reducing bacterium, Desulfovibrio vulgaris Hildenborough. Our searches of the raw spectra led us to discover several post-translationally modified peptides in D. vulgaris. Of these, several peptides containing a lysine with a +42 Da modification were found reproducibly across all data sets. Both acetylation and trimethylation have the same nominal +42 Da mass, and are therefore candidates for this modification. Several spectra were identified having markers for trimethylation, while one is consistent with an acetylation. Surprisingly, these modified peptides predominantly mapped to proteins involved in sulfate respiration. Other highly expressed proteins in D. vulgaris, such as enzymes involved in electron transport and other central metabolic processes, did not contain this …
Date: March 1, 2008
Creator: Gaucher, S. P.; Redding, A. M.; Mukhopadhyay, A.; Keasling, J. D. & Singh, A. K.
Object Type: Article
System: The UNT Digital Library
Studies of Correlated-Electron Systems in High Magnetic Fields and at High Pressures (open access)

Studies of Correlated-Electron Systems in High Magnetic Fields and at High Pressures

None
Date: March 26, 2008
Creator: Cornelius, Dr. Andrew
Object Type: Report
System: The UNT Digital Library
Hydrogen Scenario Analysis Summary Report: Analysis of the Transition to Hydrogen Fuel Cell Vehicles and the Potential Hydrogen Energy Infrastructure Requirements (open access)

Hydrogen Scenario Analysis Summary Report: Analysis of the Transition to Hydrogen Fuel Cell Vehicles and the Potential Hydrogen Energy Infrastructure Requirements

Achieving a successful transition to hydrogen-powered vehicles in the U.S. automotive market will require strong and sustained commitment by hydrogen producers, vehicle manufacturers, transporters and retailers, consumers, and governments. The interaction of these agents in the marketplace will determine the real costs and benefits of early market transformation policies, and ultimately the success of the transition itself. The transition to hydrogen-powered transportation faces imposing economic barriers. The challenges include developing and refining a new and different power-train technology, building a supporting fuel infrastructure, creating a market for new and unfamiliar vehicles, and achieving economies of scale in vehicle production while providing an attractive selection of vehicle makes and models for car-buyers. The upfront costs will be high and could persist for a decade or more, delaying profitability until an adequate number of vehicles can be produced and moved into consumer markets. However, the potential rewards to the economy, environment, and national security are immense. Such a profound market transformation will require careful planning and strong, consistent policy incentives. Section 811 of the Energy Policy Act (EPACT) of 2005, Public Law 109-59 (U.S. House, 2005), calls for a report from the Secretary of Energy on measures to support the transition to …
Date: March 1, 2008
Creator: Greene, David L.; Leiby, Paul Newsome; James, Brian; Perez, Julie; Melendez, Margo; Milbrandt, Anelia et al.
Object Type: Report
System: The UNT Digital Library
Basalt weathering rates on Earth and the duration of liquid water on the plains of Gusev Crater, Mars (open access)

Basalt weathering rates on Earth and the duration of liquid water on the plains of Gusev Crater, Mars

Where Martian rocks have been exposed to liquid water, chemistry versus depth profiles could elucidate both Martian climate history and potential for life. The persistence of primary minerals in weathered profiles constrains the exposure time to liquid water: on Earth, mineral persistence times range from {approx}10 ka (olivine) to {approx}250 ka (glass) to {approx}1Ma (pyroxene) to {approx}5Ma (plagioclase). Such persistence times suggest mineral persistence minima on Mars. However, Martian solutions may have been more acidic than on Earth. Relative mineral weathering rates observed for basalt in Svalbard (Norway) and Costa Rica demonstrate that laboratory pH trends can be used to estimate exposure to liquid water both qualitatively (mineral absence or presence) and quantitatively (using reactive transport models). Qualitatively, if the Martian solution pH > {approx}2, glass should persist longer than olivine; therefore, persistence of glass may be a pH-indicator. With evidence for the pH of weathering, the reactive transport code CrunchFlow can quantitatively calculate the minimum duration of exposure to liquid water consistent with a chemical profile. For the profile measured on the surface of Humphrey in Gusev Crater, the minimum exposure time is 22 ka. If correct, this estimate is consistent with short-term, episodic alteration accompanied by ongoing surface …
Date: March 15, 2008
Creator: Steefel, Carl; Hausrath, E. M.; Navarre-Sitchler, A. K.; Sak, P. B.; Steefel, C. & Brantley, S. L.
Object Type: Article
System: The UNT Digital Library
Measurement of CP Violation in B0 to Phi K0, and of Branching Fraction and CP Violation in B0 to F0(980) K0(S) (open access)

Measurement of CP Violation in B0 to Phi K0, and of Branching Fraction and CP Violation in B0 to F0(980) K0(S)

The authors measure the time-dependent CP asymmetry parameters in B{sup 0} {yields} K{sup +}K{sup -}K{sup 0} based on a data sample of approximately 277 million B-meson pairs recorded at the {Upsilon}(4S) resonance with the BABAR detector at the PEP-II B-meson Factory at SLAC. They reconstruct two-body B{sup 0} decays to {phi}(1020)K{sub s}{sup 0} and {phi}(1020)K{sub L}{sup 0}. Using a time-dependent maximum-likelihood fit, they measure sin2{beta}{sub eff}({phi}K{sup 0}) = 0.48 {+-} 0.28 {+-} 0.10, and C({phi}K{sup 0}) = 0.16 {+-} 0.25 {+-} 0.09, where the first error is statistical, and the second is systematic. They also present measurements of the CP-violating asymmetries in the decay B{sup 0} {yields} f{sub 0}({yields} {pi}{sup +}{pi}{sup -})K{sub s}{sup 0}. The results are obtained from a data sample of 209 x 10{sup 6} {Upsilon}(4S) {yields} B{bar B} decays, also collected with the BABAR detector at the PEP-II asymmetric-energy B Factory at SLAC. From a time-dependent maximum-likelihood fit they measure the mixing-induced CP violation parameter S(f{sub 0}(980)K{sub S}{sup 0}) = - sin 2{beta}{sub eff}f{sub 0}(980)K{sub S}{sup 0} = -0.95{sub -0.23}{sup +0.32} {+-} 0.10 and the direct CP violation parameter C(f{sub 0}(980)K{sub S}{sup 0}) = - 0.24 {+-} 0.31 {+-} 0.15, where the first errors are statistical and …
Date: March 10, 2008
Creator: Kutter, Paul E.
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Texas Parks & Wildlife, Volume 66, Number 3, March 2008 (open access)

Texas Parks & Wildlife, Volume 66, Number 3, March 2008

Magazine discussing natural resources, parks, hunting and fishing, and other information related to the outdoors in Texas.
Date: March 2008
Creator: Texas. Parks and Wildlife Department.
Object Type: Journal/Magazine/Newsletter
System: The Portal to Texas History
Environmental Molecular Sciences Laboratory 2007 Annual Report (open access)

Environmental Molecular Sciences Laboratory 2007 Annual Report

This annual report provides details on the research conducted at the Environmental Molecular Sciences Laboratory in Fiscal Year 2007 and path forward for capability upgrades in Fiscal Year 2008.
Date: March 19, 2008
Creator: Showalter, Mary Ann & Foster, Nancy S.
Object Type: Report
System: The UNT Digital Library
Improving Gas Flooding Efficiency (open access)

Improving Gas Flooding Efficiency

This study focuses on laboratory studies with related analytical and numerical models, as well as work with operators for field tests to enhance our understanding of and capabilities for more efficient enhanced oil recovery (EOR). Much of the work has been performed at reservoir conditions. This includes a bubble chamber and several core flood apparatus developed or modified to measure interfacial tension (IFT), critical micelle concentration (CMC), foam durability, surfactant sorption at reservoir conditions, and pressure and temperature effects on foam systems.Carbon dioxide and N{sub 2} systems have been considered, under both miscible and immiscible conditions. The injection of CO2 into brine-saturated sandstone and carbonate core results in brine saturation reduction in the range of 62 to 82% brine in the tests presented in this paper. In each test, over 90% of the reduction occurred with less than 0.5 PV of CO{sub 2} injected, with very little additional brine production after 0.5 PV of CO{sub 2} injected. Adsorption of all considered surfactant is a significant problem. Most of the effect is reversible, but the amount required for foaming is large in terms of volume and cost for all considered surfactants. Some foams increase resistance to the value beyond what is …
Date: March 31, 2008
Creator: Grigg, Reid; Svec, Robert; Zeng, Zheng; Mikhalin, Alexander; Lin, Yi; Yin, Guoqiang et al.
Object Type: Report
System: The UNT Digital Library
Defense Acquisitions: Assessments of Selected Weapon Programs (open access)

Defense Acquisitions: Assessments of Selected Weapon Programs

A letter report issued by the Government Accountability Office with an abstract that begins "This report is GAO's sixth annual assessment of selected weapon programs. Since 2000, the Department of Defense (DOD) has roughly doubled its planned investment in new systems from $790 billion to $1.6 trillion in 2007, but acquisition outcomes in terms of cost and schedule have not improved. Total acquisition costs for major defense programs in the fiscal year 2007 portfolio have increased 26 percent from first estimates, compared with 6 percent in 2000. Programs have also often failed to deliver capabilities when promised. DOD's acquisition outcomes appear increasingly suboptimal, a condition that needs to be corrected given the pressures faced by the department from other military and major nondiscretionary government demands. This report provides congressional and DOD decision makers with an independent, knowledge-based assessment of defense programs, identifying potential risks when a program's projected attainment of knowledge diverges from best practices. The programs assessed--most of which are considered major acquisitions by DOD--were selected using several factors: high dollar value, acquisition stage, and congressional interest. This report also highlights overall trends in DOD acquisition outcomes and issues raised by the cumulative experience of individual programs. GAO updates …
Date: March 31, 2008
Creator: United States. Government Accountability Office.
Object Type: Report
System: The UNT Digital Library
FCC Record, Volume 23, No. 6, Pages 4465 to 5426, March 17 - March 28, 2008 (open access)

FCC Record, Volume 23, No. 6, Pages 4465 to 5426, March 17 - March 28, 2008

Biweekly, comprehensive compilation of decisions, reports, public notices, and other documents of the U.S. Federal Communications Commission.
Date: March 2008
Creator: United States. Federal Communications Commission.
Object Type: Book
System: The UNT Digital Library