The Absence of Plasma in"Spark Plasma Sintering" (open access)

The Absence of Plasma in"Spark Plasma Sintering"

Spark plasma sintering (SPS) is a remarkable method for synthesizing and consolidating a large variety of both novel and traditional materials. The process typically uses moderate uni-axial pressures (<100 MPa) in conjunction with a pulsing on-off DC current during operation. There are a number of mechanisms proposed to account for the enhanced sintering abilities of the SPS process. Of these mechanisms, the one most commonly put forth and the one that draws the most controversy involves the presence of momentary plasma generated between particles. This study employees three separate experimental methods in an attempt to determine the presence or absence of plasma during SPS. The methods employed include: in-situ atomic emission spectroscopy, direct visual observation and ultra-fast in-situ voltage measurements. It was found using these experimental techniques that no plasma is present during the SPS process. This result was confirmed using several different powders across a wide spectrum of SPS conditions.
Date: April 10, 2008
Creator: Hulbert, Dustin M.; Anders, Andre; Dudina, Dina V.; Andersson, Joakim; Jiang, Dongtao; Unuvar, Cosan et al.
Object Type: Article
System: The UNT Digital Library
Chemical imaging of biological materials by NanoSIMS using isotopic and elemental labels (open access)

Chemical imaging of biological materials by NanoSIMS using isotopic and elemental labels

The NanoSIMS 50 combines unprecedented spatial resolution (as good as 50 nm) with ultra-high sensitivity (minimum detection limit of {approx}200 atoms). The NanoSIMS 50 incorporates an array of detectors, enabling simultaneous collection of 5 species originating from the same sputtered volume of a sample. The primary ion beam (Cs{sup +} or O{sup -}) can be scanned across the sample to produce quantitative secondary ion images. This capability for multiple isotope imaging with high spatial resolution provides a novel new approach to the study of biological materials. Studies can be made of sub-regions of tissues, mammalian cells, and bacteria. Major, minor and trace element distributions can be mapped on a submicron scale, growth and metabolism can be tracked using stable isotope labels, and biogenic origin can be determined based on composition. We have applied this technique extensively to mammalian and prokaryotic cells and bacterial spores. The NanoSIMS technology enables the researcher to interrogate the fate of molecules of interest within cells and organs through elemental and isotopic labeling. Biological applications at LLNL will be discussed.
Date: April 10, 2006
Creator: Weber, P K; Fallon, S J; Pett-Ridge, J; Ghosal, S & Hutcheon, I D
Object Type: Article
System: The UNT Digital Library
Origin and Propagation of Cosmic Rays (Some Highlights) (open access)

Origin and Propagation of Cosmic Rays (Some Highlights)

None
Date: April 10, 2008
Creator: Moskalenko, Igor V. & /Stanford U., HEPL /KIPAC, Menlo Park
Object Type: Article
System: The UNT Digital Library
Metrics and Benchmarks for Energy Efficiency in Laboratories (open access)

Metrics and Benchmarks for Energy Efficiency in Laboratories

A wide spectrum of laboratory owners, ranging from universities to federal agencies, have explicit goals for energy efficiency in their facilities. For example, the Energy Policy Act of 2005 (EPACT 2005) requires all new federal buildings to exceed ASHRAE 90.1-2004 [1] by at least 30%. A new laboratory is much more likely to meet energy efficiency goals if quantitative metrics and targets are specified in programming documents and tracked during the course of the delivery process. If not, any additional capital costs or design time associated with attaining higher efficiencies can be difficult to justify. This article describes key energy efficiency metrics and benchmarks for laboratories, which have been developed and applied to several laboratory buildings--both for design and operation. In addition to traditional whole building energy use metrics (e.g. BTU/ft{sup 2}.yr, kWh/m{sup 2}.yr), the article describes HVAC system metrics (e.g. ventilation W/cfm, W/L.s{sup -1}), which can be used to identify the presence or absence of energy features and opportunities during design and operation.
Date: April 10, 2008
Creator: Engineers, Rumsey; Mathew, Paul; Mathew, Paul; Greenberg, Steve; Sartor, Dale; Rumsey, Peter et al.
Object Type: Article
System: The UNT Digital Library
Field evidence for strong chemical separation of contaminants in the Hanford Vadose Zone (open access)

Field evidence for strong chemical separation of contaminants in the Hanford Vadose Zone

Water and chemical transport from a point source withinvadose zone sediments at Hanford were examined with a leak testconsisting of five 3800-liter aliquots of water released at 4.5 m depthevery week over a 4-week period. The third aliquot contained bromide, D2Oand 87Sr. Movement of the tracers was monitored for 9 months by measuringpore water compositions of samples from boreholes drilled 2-8 m from theinjection point. Graded sedimentary layers acting as natural capillarybarriers caused significant lateral spreading of the leak water. D2Oconcentrations>50 percent of the concentration in the tracer aliquotwere detected at 9-11 m depth. However, increased water contents, lowerd18O values, and geophysical monitoring of moisture changes at otherdepths signified high concentrations of leak fluids were added where D2Oconcentrations were<3 percent above background, suggesting limitedmixing between different aliquots of the leak fluids. Initially highbromide concentrations decreased more rapidly over time than D2O,suggesting enhanced transport of bromide due to anion exclusion. Nosignificant increase in 87Sr was detected in the sampled pore water,indicating strong retardation of Sr by the sediments. These resultshighlight some of the processes strongly affecting chemical transport inthe vadose zone and demonstrate the significant separation of contaminantplumes that can occur.
Date: April 10, 2007
Creator: Conrad, Mark E.; DePaolo, Donald J.; Maher, Katharine; Gee,Glendon W. & Ward, Anderson L.
Object Type: Article
System: The UNT Digital Library
Characterization of chemical bonding in low-k dielectric materialsfor interconnect isolation: a xas and eels study (open access)

Characterization of chemical bonding in low-k dielectric materialsfor interconnect isolation: a xas and eels study

The use of low dielectric constant materials in the on-chipinterconnect process reduces interconnect delay, power dissipation andcrosstalk noise. To achieve the requirements of the ITRS for 2007-2009minimal sidewall damage from etch, ash or cleans is required. In chemicalvapor deposited (CVD) organo-silicate glass (OSG) which are used asintermetal dielectric (IMD) materials the substitution of oxygen in SiO2by methyl groups (-CH3) reduces the permittivity significantly (from 4.0in SiO2 to 2.6-3.3 in the OSG), since the electronic polarizability islower for Si-C bonds than for Si-O bonds. However, plasma processing forresist stripping, trench etching and post-etch cleaning removes C and Hcontaining molecular groups from the near-surface layer of OSG.Therefore, compositional analysis and chemical bonding characterizationof structured IMD films with nanometer resolution is necessary forprocess optimization. OSG thin films as-deposited and after plasmatreatment are studied using X-ray absorption spectroscopy (XAS) andelectron energy loss spectroscopy (EELS). In both techniques, the finestructure near the C1s absorption or energy loss edge, respectively,allows to identify C-H, C-C, and C-O bonds. This gives the opportunity todifferentiate between individual low-k materials and their modifications.The O1s signal is less selective to individual bonds. XAS spectra havebeen recorded for non-patterned films and EELS spectra for patternedstructures. The chemical bonding is compared for as-deposited …
Date: April 10, 2006
Creator: Hoffmann, P.; Schmeisser, D.; Engelmann, H. J.; Zschech, E.; Stegmann, H.; Himpsel, F. et al.
Object Type: Article
System: The UNT Digital Library
Barium in Twilight Zone suspended matter as a potential proxy for particulate organic carbon remineralization: Results for the North Pacific (open access)

Barium in Twilight Zone suspended matter as a potential proxy for particulate organic carbon remineralization: Results for the North Pacific

This study focuses on the fate of exported organic carbon in the twilight zone at two contrasting environments in the North Pacific: the oligotrophic ALOHA site (22 degrees 45 minutes N 158 degrees W; Hawaii; studied during June-July 2004) and the mesotrophic Subarctic Pacific K2 site (47 degrees N, 161 degrees W; studied during July-August 2005). Earlier work has shown that non-lithogenic, excess particulate Ba (Ba{sub xs}) in the mesopelagic water column is a potential proxy of organic carbon remineralization. In general Ba{sub xs} contents were significantly larger at K2 than at ALOHA. At ALOHA the Ba{sub xs} profiles from repeated sampling (5 casts) showed remarkable consistency over a period of three weeks, suggesting that the system was close to being at steady state. In contrast, more variability was observed at K2 (6 casts sampled) reflecting the more dynamic physical and biological conditions prevailing in this environment. While for both sites Ba{sub xs} concentrations increased with depth, at K2 a clear maximum was present between the base of the mixed layer at around 50m and 500m, reflecting production and release of Ba{sub xs}. Larger mesopelagic Ba{sub xs} contents and larger bacterial production in the twilight zone at the K2 site …
Date: April 10, 2008
Creator: Dehairs, F.; Jacquet, S.; Savoye, N.; Van Mooy, B. A. S.; Buesseler, K.; Bishop, J. K. B. et al.
Object Type: Article
System: The UNT Digital Library
Minior Actinide Doppler Coefficient Measurement Assessment (open access)

Minior Actinide Doppler Coefficient Measurement Assessment

The "Minor Actinide Doppler Coefficient Measurement Assessment" was a Department of Energy (DOE) U-NERI funded project intended to assess the viability of using either the FLATTOP or the COMET critical assembly to measure high temperature Doppler coefficients. The goal of the project was to calculate using the MCNP5 code the gram amounts of Np-237, Pu-238, Pu-239, Pu-241, AM-241, AM-242m, Am-243, and CM-244 needed to produce a 1E-5 in reactivity for a change in operating temperature 800C to 1000C. After determining the viability of using the assemblies and calculating the amounts of each actinide an experiment will be designed to verify the calculated results. The calculations and any doncuted experiments are designed to support the Advanced Fuel Cycle Initiative in conducting safety analysis of advanced fast reactor or acceoerator-driven transmutation systems with fuel containing high minor actinide content.
Date: April 10, 2008
Creator: Hertel, Nolan E. & Blaylock, Dwayne
Object Type: Report
System: The UNT Digital Library
Documentation of Naval Reactors Papers and Presentations for the Space Technology and International Forum (STAIF) 2006 (open access)

Documentation of Naval Reactors Papers and Presentations for the Space Technology and International Forum (STAIF) 2006

None
Date: April 10, 2006
Creator: Ashcroft, JM
Object Type: Report
System: The UNT Digital Library
Hydrogeologic Assessment of the 4-S Land and Cattle CompanyRanch (open access)

Hydrogeologic Assessment of the 4-S Land and Cattle CompanyRanch

Hydrogeological assessment of the 4-S Land and Cattle Company (4-S Ranch) was conducted using a combination of field investigations and a survey of available literature from nearby agricultural water districts and other entities. The 4-S Ranch has been able to meet most of its own water needs providing irrigated pasture for beef cattle by an active program of shallow groundwater pumping in these miconfined aquifer above the Corcoran Clay. Comparison of groundwater pumping on the 4-S Ranch property with groundwater pumping in the adjacent Merquin and Stevinson Water Districts shows great similarity in the well screened depths and the quality of the groundwater produced by the well fields. The pump yield for the eight active production wells on the 4-S property are comparable to the production and drainage wells in the adjacent water districts. Like these Districts the 4-S Ranch lies close to the Valley trough in a historic discharge area. The 4-S Ranch is unique in that it is bounded and bisected by several major water conveyance facilities including Bear Creek. Although the large number of potential recharge structures would suggest significant groundwater conjunctive use potential the major well field development has occurred along the length of the Eastside …
Date: April 10, 2006
Creator: Quinn, Nigel W.T.
Object Type: Report
System: The UNT Digital Library
Carbon Isotopic Studies of Assimilated and Ecosystem Respired CO2 in a Southeastern Pine Forest (open access)

Carbon Isotopic Studies of Assimilated and Ecosystem Respired CO2 in a Southeastern Pine Forest

Carbon dioxide is the major “greenhouse” gas responsible for global warming. Southeastern pine forests appear to be among the largest terrestrial sinks of carbon dioxide in the US. This collaborative study specifically addressed the isotopic signatures of the large fluxes of carbon taken up by photosynthesis and given off by respiration in this ecosystem. By measuring these isotopic signatures at the ecosystem level, we have provided data that will help to more accurately quantify the magnitude of carbon fluxes on the regional scale and how these fluxes vary in response to climatic parameters such as rainfall and air temperature. The focus of the MBL subcontract was to evaluate how processes operating at the physiological and ecosystem scales affects the resultant isotopic signature of plant waxes that are emitted as aerosols into the convective boundary layer. These wax aerosols provide a large-spatial scale integrative signal of isotopic discrimination of atmospheric carbon dioxide by terrestrial photosynthesis (Conte and Weber 2002). The ecosystem studies have greatly expanded of knowledge of wax biosynthetic controls on their isootpic signature The wax aerosol data products produced under this grant are directly applicable as input for global carbon modeling studies that use variations in the concentration and …
Date: April 10, 2008
Creator: Conte, Maureen H.
Object Type: Text
System: The UNT Digital Library
Microgrids: An emerging paradigm for meeting building electricityand heat requirements efficiently and with appropriate energyquality (open access)

Microgrids: An emerging paradigm for meeting building electricityand heat requirements efficiently and with appropriate energyquality

The first major paradigm shift in electricity generation,delivery, and control is emerging in the developed world, notably Europe,North America, and Japan. This shift will move electricity supply awayfrom the highly centralised universal service quality model with which weare familiar today towards a more dispersed system with heterogeneousqualities of service. One element of dispersed control is the clusteringof sources and sinks into semi-autonomous mu grids (microgrids).Research, development, demonstration, and deployment (RD3) of mu gridsare advancing rapidly on at least three continents, and significantdemonstrations are currently in progress. This paradigm shift will resultin more electricity generation close to end-uses, often involvingcombined heat and power application for building heating and cooling,increased local integration of renewables, and the possible provision ofheterogeneous qualities of electrical service to match the requirementsof various end-uses. In Europe, mu grid RD3 is entering its third majorround under the 7th European Commission Framework Programme; in the U.S.,one specific mu grid concept is undergoing rigorous laboratory testing,and in Japan, where the most activity exists, four major publiclysponsored and two privately sponsored demonstrations are in progress.This evolution poses new challenges to the way buildings are designed,built, and operated. Traditional building energy supply systems willbecome much more complex in at least three ways: …
Date: April 10, 2007
Creator: Marnay, Chris & Firestone, Ryan
Object Type: Article
System: The UNT Digital Library
The NLO Multileg Working Group: Summary Report (open access)

The NLO Multileg Working Group: Summary Report

None
Date: April 10, 2008
Creator: Bern, Z.; Bernicot, C.; Binoth, T.; Boudjema, F.; Britto, R.; Campbell, J. et al.
Object Type: Article
System: The UNT Digital Library
Isotopic Composition of Cosmic-Ray Sources (open access)

Isotopic Composition of Cosmic-Ray Sources

None
Date: April 10, 2008
Creator: Moskalenko, Igor V.; Strong, Andrew W.; Porter, Troy A.; /Stanford U., HEPL /KIPAC, Menlo Park; Strong, Andrew W. & Porter, Troy A.
Object Type: Article
System: The UNT Digital Library
Enhancing Carbon Fixation by Metabolic Engineering: A Model System of Complex Network Modulation (open access)

Enhancing Carbon Fixation by Metabolic Engineering: A Model System of Complex Network Modulation

In the first two years of this research we focused on the development of a DNA microarray for transcriptional studies in the photosynthetic organism Synechocystis and the elucidation of the metabolic pathway for biopolymer synthesis in this organism. In addition we also advanced the molecular biological tools for metabolic engineering of biopolymer synthesis in Synechocystis and initiated a series of physiological studies for the elucidation of the carbon fixing pathways and basic central carbon metabolism of these organisms. During the last two-year period we focused our attention on the continuation and completion of the last task, namely, the development of tools for basic investigations of the physiology of these cells through, primarily, the determination of their metabolic fluxes. The reason for this decision lies in the importance of fluxes as key indicators of physiology and the high level of information content they carry in terms of identifying rate limiting steps in a metabolic pathway. While flux determination is a well-advanced subject for heterotrophic organisms, for the case of autotrophic bacteria, like Synechocystis, some special challenges had to be overcome. These challenges stem mostly from the fact that if one uses {sup 13}C labeled CO{sub 2} for flux determination, the {sup …
Date: April 10, 2008
Creator: Stephanopoulos, Dr. Gregory
Object Type: Report
System: The UNT Digital Library
Detecting antipersonnel mines with a handheld parabolic reflector transmitter/multistatic receiver impulse gpr (open access)

Detecting antipersonnel mines with a handheld parabolic reflector transmitter/multistatic receiver impulse gpr

A novel handheld time-domain array GPR antipersonnel mine detection system using an offset paraboloidal reflector antenna is described. The reflector collimates rays from an ultra-wideband transmitting feed, directing the microwave impulse forward, in front of the antenna structure. As such, much of the ground reflected wave is directed further forward, away from the operator, the reflector, and the receiving antennas, and thereby reducing the major source of clutter. The wave transmitted into the ground that interacts with the target, generating significant backscatter returning toward the receiving antennas. These receiving antennas are configured in a 2 by 2 array to provide spatial focusing in both the along- and cross-track directions. This system has been built and tested at both Lawrence Livermore National Laboratory, and GeoCenters, Inc. In both cases, custom-built wideband antenna elements generate narrow pulse shapes, which allow for resolving small non-metallic targets buried at shallow depths. The LLNL's Micro-Power Impulse Radar (MIR) operates in the 1.5 to 5 GHz range a very narrow pulse shape. The Geo-Centers wideband TEMR antenna elements have higher power, though lower frequency range (850 to 1700 MHz), and generate less residual ringing in the time signal. Preliminary measured data from both systems indicate that …
Date: April 10, 2000
Creator: Rappaport, C.; Yang, B.; Azevedo, S.; Rosenbury, T.; Gough, J. & Dean, A.
Object Type: Article
System: The UNT Digital Library
Microfluidic Tools for Biological Sample Preparation (open access)

Microfluidic Tools for Biological Sample Preparation

Researchers at Lawrence Livermore National Laboratory are developing means to collect and identify fluid-based biological pathogens in the forms of proteins, viruses, and bacteria. To support detection instruments, we are developing a flexible fluidic sample preparation unit. The overall goal of this Microfluidic Module is to input a fluid sample, containing background particulates and potentially target compounds, and deliver a processed sample for detection. We are developing techniques for sample purification, mixing, and filtration that would be useful to many applications including immunologic and nucleic acid assays. Sample preparation functions are accomplished with acoustic radiation pressure, dielectrophoresis, and solid phase extraction. We are integrating these technologies into packaged systems with pumps and valves to control fluid flow and investigating small-scale detection methods.
Date: April 10, 2002
Creator: Visuri, S R; Ness, K; Dzenitis, J; Benett, B; Bettencourt, K; Hamilton, J et al.
Object Type: Article
System: The UNT Digital Library
Escapement and Productivity of Spring Chinook Salmon and Summer Steelhead in the John Day River Basin, 2005-2006 Annual Technical Report. (open access)

Escapement and Productivity of Spring Chinook Salmon and Summer Steelhead in the John Day River Basin, 2005-2006 Annual Technical Report.

The objectives are: (1) Estimate number and distribution of spring Chinook salmon Oncorhynchus tshawytscha redds and spawners in the John Day River subbasin; and (2) Estimate smolt-to-adult survival rates (SAR) and out-migrant abundance for spring Chinook and summer steelhead O. mykiss and life history characteristics of summer steelhead. The John Day River subbasin supports one of the last remaining intact wild populations of spring Chinook salmon and summer steelhead in the Columbia River Basin. These populations, however, remain depressed relative to historic levels. Between the completion of the life history and natural escapement study in 1984 and the start of this project in 1998, spring Chinook spawning surveys did not provide adequate information to assess age structure, progeny-to-parent production values, smolt-to-adult survival (SAR), or natural spawning escapement. Further, only very limited information is available for steelhead life history, escapement, and productivity measures in the John Day subbasin. Numerous habitat protection and rehabilitation projects to improve salmonid freshwater production and survival have also been implemented in the basin and are in need of effectiveness monitoring. While our monitoring efforts outlined here will not specifically measure the effectiveness of any particular project, they will provide much needed background information for developing context …
Date: April 10, 2009
Creator: Schultz, Terra Lang; Wilson, Wayne H. & Ruzycki, James R.
Object Type: Report
System: The UNT Digital Library
Sampling Artifacts from Conductive Silicone Tubing (open access)

Sampling Artifacts from Conductive Silicone Tubing

None
Date: April 10, 2009
Creator: Timko, Michael T.; Yu, Zhenhong; Kroll, Jesse; Jayne, John T.; Worsnop, Douglas R.; Liscinsky, David et al.
Object Type: Article
System: The UNT Digital Library
Chemical Effect of Dry and Wet Cleaning of the Ru Protective Layer of the Extreme ultraviolet (EUV) Lithography Reflector (open access)

Chemical Effect of Dry and Wet Cleaning of the Ru Protective Layer of the Extreme ultraviolet (EUV) Lithography Reflector

The authors report the chemical influence of cleaning of the Ru capping layer on the extreme ultraviolet (EUV) reflector surface. The cleaning of EUV reflector to remove the contamination particles has two requirements: to prevent corrosion and etching of the reflector surface and to maintain the reflectivity functionality of the reflector after the corrosive cleaning processes. Two main approaches for EUV reflector cleaning, wet chemical treatments [sulfuric acid and hydrogen peroxide mixture (SPM), ozonated water, and ozonated hydrogen peroxide] and dry cleaning (oxygen plasma and UV/ozone treatment), were tested. The changes in surface morphology and roughness were characterized using scanning electron microscopy and atomic force microscopy, while the surface etching and change of oxidation states were probed with x-ray photoelectron spectroscopy. Significant surface oxidation of the Ru capping layer was observed after oxygen plasma and UV/ozone treatment, while the oxidation is unnoticeable after SPM treatment. Based on these surface studies, the authors found that SPM treatment exhibits the minimal corrosive interactions with Ru capping layer. They address the molecular mechanism of corrosive gas and liquid-phase chemical interaction with the surface of Ru capping layer on the EUV reflector.
Date: April 10, 2009
Creator: Belau, Leonid; Park, Jeong Y.; Liang, Ted; Seo, Hyungtak & Somorjai, Gabor A.
Object Type: Article
System: The UNT Digital Library
Comprehensive Mechanisms for Combustion Chemistry: An Experimental and Numerical Study with Emphasis on Applied Sensitivity Analysis (open access)

Comprehensive Mechanisms for Combustion Chemistry: An Experimental and Numerical Study with Emphasis on Applied Sensitivity Analysis

This project was an integrated experimental/numerical effort to study pyrolysis and oxidation reactions and mechanisms for small-molecule hydrocarbon structures under conditions representative of combustion environments. The experimental aspects of the work were conducted in large-diameter flow reactors, at 0.3 to 18 atm pressure, 500 to 1100 K temperature, and 10<SUP>-2</SUP> to 2 seconds reaction time. Experiments were also conducted to determine reference laminar flame speeds using a premixed laminar stagnation flame experiment and particle image velocimetry, as well as pressurized bomb experiments. Flow reactor data for oxidation experiments include: (1)adiabatic/isothermal species time-histories of a reaction under fixed initial pressure, temperature, and composition; to determine the species present after a fixed reaction time, initial pressure; (2)species distributions with varying initial reaction temperature; (3)perturbations of a well-defined reaction systems (e.g. CO/H<SUB>2</SUB>/O<SUB>2</SUB> or H<SUB>2</SUB>/O<SUB>2</SUB>)by the addition of small amounts of an additive species. Radical scavenging techniques are applied to determine unimolecular decomposition rates from pyrolysis experiments. Laminar flame speed measurements are determined as a function of equivalence ratio, dilution, and unburned gas temperature at 1 atm pressure. Hierarchical, comprehensive mechanistic construction methods were applied to develop detailed kinetic mechanisms which describe the measurements and literature kinetic data. Modeling using well-defined and validated mechanisms …
Date: April 10, 2009
Creator: Dryer, Frederick L.
Object Type: Report
System: The UNT Digital Library
Monitoring and Evaluation of Supplemented Spring Chinook Salmon and Life Histories of Wild Summer Steelhead in the Grande Ronde Basin, 2007 Annual Report. (open access)

Monitoring and Evaluation of Supplemented Spring Chinook Salmon and Life Histories of Wild Summer Steelhead in the Grande Ronde Basin, 2007 Annual Report.

This is the ninth annual report for a multi-year project designed to monitor and evaluate supplementation of endemic spring Chinook salmon in Catherine Creek and the upper Grande Ronde River. These two streams historically supported anadromous fish populations that provided significant tribal and non-tribal fisheries, but in recent years, have experienced severe declines in abundance. Conventional and captive broodstock supplementation methods are being used to restore these spring Chinook salmon populations. Spring Chinook salmon populations in Catherine Creek and the upper Grande Ronde River, and other streams in the Snake River Basin have experienced severe declines in abundance over the past two decades (Nehlsen et al. 1991). A supplementation program was initiated in Catherine Creek and the upper Grande Ronde River, incorporating the use of both captive and conventional broodstock methods, in order to prevent extinction in the short term and eventually rebuild populations. The captive broodstock component of the program (BPA Project 199801001) uses natural-origin parr collected by seining and reared to maturity at facilities near Seattle, Washington (Manchester Marine Laboratory) and Hood River, Oregon (Bonneville Hatchery). Spawning occurs at Bonneville Hatchery, and resulting progeny are reared in hatcheries. Shortly before outmigration in the spring, juveniles are transferred to …
Date: April 10, 2009
Creator: Boe, Stephen J.; Crump, Carrie A. & Weldert, Rey L.
Object Type: Report
System: The UNT Digital Library
Cosmology with X-ray Cluster Baryons (open access)

Cosmology with X-ray Cluster Baryons

X-ray cluster measurements interpreted with a universal baryon/gas mass fraction can theoretically serve as a cosmological distance probe. We examine issues of cosmological sensitivity for current (e.g., Chandra X-ray Observatory, XMM-Newton) and next generation (e.g., Con-X, XEUS) observations, along with systematic uncertainties and biases. To give competitive next generation constraints on dark energy, we find that systematics will need to be controlled to better than 1percent and any evolution in f_gas (and other cluster gas properties) must be calibrated so the residual uncertainty is weaker than (1+z)0.03.
Date: April 10, 2007
Creator: Linder, Eric V.
Object Type: Article
System: The UNT Digital Library
Novel High Transverse Momentum Phenomena in Hadronic and Nuclear Collisions (open access)

Novel High Transverse Momentum Phenomena in Hadronic and Nuclear Collisions

I discuss a number of novel phenomenological features of QCD in high transverse momentum reactions. The presence of direct higher-twist processes, where a proton is produced directly in the hard subprocess, can explain the 'baryon anomaly' - the large proton-to-pion ratio seen at RHIC in high centrality heavy ion collisions. Direct hadronic processes can also account for the deviation from leading-twist PQCD scaling at fixed x{sub T} = 2 p{sub T}/{radical}s. I suggest that the 'ridge' --the same-side long-range rapidity correlation observed at RHIC in high centrality heavy ion collisions is due to the imprint of semihard DGLAP gluon radiation from initial-state partons which have transverse momenta biased toward the trigger. A model for early thermalization of the quark-gluon medium is also outlined. Rescattering interactions from gluon-exchange, normally neglected in the parton model, have a profound effect in QCD hard-scattering reactions, leading to leading-twist single-spin asymmetries, diffractive deep inelastic scattering, diffractive hard hadronic reactions, the breakdown of the Lam-Tung relation in Drell-Yan reactions, nuclear shadowing--all leading-twist dynamics not incorporated in the light-front wavefunctions of the target computed in isolation. Anti shadowing is shown to be quark flavor specific and thus different in charged and neutral deep inelastic lepton-nucleus scattering. I …
Date: April 10, 2009
Creator: Brodsky, Stanley J.
Object Type: Article
System: The UNT Digital Library