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465 Matching Results

Start Over Decade 2000-2009 Month April Day 10th Language English

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(open access)

NASA: Compliance With Cost Limits Cannot Be Verified

Correspondence issued by the General Accounting Office with an abstract that begins "The National Aeronautics and Space Administration's (NASA) authorization act for fiscal year 2000 limits expenditures for space station development to $25 billion and for shuttle launches to $17.7 billion. The act also requires NASA to (1) account for and report amounts obligated to date against the cost limits, (2) identify the amounts needed for future development and completion of the space station, and (3) arrange for GAO to verify the accounting within 60 days after submission of the budget request. Last year, GAO reported that NASA, as part of its fiscal year 2002 budget request, did not comply with the act's requirement to use obligations as its basis for reporting against the cost limits but instead used budget authority. The agency was also unable to provide detailed support for the amounts obligated against the limits for evaluation within the 60 days, but said that it could have provided the information if given more time. After a protracted effort, NASA has acknowledged that its systems cannot provide the data needed to support amounts obligated against the limits. NASA's inability to provide detailed data is due to its lack of …

Date: April 10, 2002

Creator: United States. General Accounting Office.

Object Type: Text

System: The UNT Digital Library

(open access)

Content Provider Interviews: Summary Report

This report is part of the Web-at-Risk project. This report summarizes the results of the interviews with content providers. Section 2 identifies the interview methodology. Section 3 describes the results and Section 4 discusses the major findings.

Date: April 10, 2006

Creator: Murray, Kathleen R.

Object Type: Report

System: The UNT Digital Library

(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

(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

(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

(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

(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

(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

(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

(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

(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

(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

(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

(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

(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

(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

(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