Thermophotovoltaic (TPV) diodes fabricated from 0.52eV lattice-matched InGaAsSb alloys are grown by Metal Organic Vapor Phase Epitaxy (MOVPE) on GaSb substrates. 4cm{sup 2} multi-chip diode modules with front-surface spectral filters were tested in a vacuum cavity and attained measured efficiency and power density of 19% and 0.58 W/cm{sup 2} respectively at operating at temperatures of T{sub radiator} = 950 C and T{sub diode} = 27 C. Device modeling and minority carrier lifetime measurements of double heterostructure lifetime specimens indicate that diode conversion efficiency is limited predominantly by interface recombination and photon energy loss to the GaSb substrate and back ohmic contact. Recent improvements to the diode include lattice-matched p-type AlGaAsSb passivating layers with interface recombination velocities less than 100 cm/s and new processing techniques enabling thinned substrates and back surface reflectors. Modeling predictions of these improvements to the diode architecture indicate that conversion efficiencies from 27-30% and {approx}0.85 W/cm{sup 2} could be attained under the above operating temperatures.

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This work summarizes recent data on minority carrier lifetime in n- and p-type double heterostructures (DHs) of 0.5-0.6 eV GaInAsSb confined with GaSb and AlGaAsSb cap layers. Recombination times were measured by time-resolved photoluminescence (TRPL) and by optical frequency response (OFR) to sinusoidal excitation. It was shown that one of the mechanisms responsible for interface recombination in GaSb/GaInAsSb/GaSb DHs is thermionic emission of carriers over the heterobarrier. Considerable improvement of carrier confinement was obtained with 1 eV AlGaAsSb cap layers. Optimization of the epitaxial growth resulted in a recombination velocity at GaInAsSb/AlGaAsSb interface as low as 30 cm/s.

The genome sequence of the solvent producing bacterium Clostridium acetobutylicum ATCC824, has been determined by the shotgun approach. The genome consists of a 3.94 Mb chromosome and a 192 kb megaplasmid that contains the majority of genes responsible for solvent production. Comparison of C. acetobutylicum to Bacillus subtilis reveals significant local conservation of gene order, which has not been seen in comparisons of other genomes with similar, or, in some cases, closer, phylogenetic proximity. This conservation allows the prediction of many previously undetected operons in both bacteria.

Antimony-based III-V thermophotovoltaic (TPV) cells are attractive converters for systems with low radiator temperature around 1100 to 1700 K, since these cells potentially can be spectrally matched to the thermal source. Cells under development include GaSb and the lattice-matched GaInAsSb/GaSb and InPAsSb/InAs quaternary systems. GaSb cell technology is the most mature, owing in part to the relative ease in preparation of the binary alloy compared to quaternary GaInAsSb and InPAsSb alloys. Device performance of 0.7-eV GaSb cells exceeds 90% of the practical limit. GaInAsSb TPV cells have been the primary focus of recent research, and cells with energy gap E{sub g} ranging from {approx}0.6 to 0.49 eV have been demonstrated. Quantum efficiency and fill factor approach theoretical limits. Open-circuit voltage factor is as high as 87% of the practical limit for the higher-E{sub g} cells, but degrades to below 80% with decreasing E{sub g} of the alloy, which might be due to Auger recombination. InPAsSb cells are the least studied, and a cell with E{sub g} = 0.45-eV has extended spectral response out to 4.3 {micro}m. This paper briefly reviews the main contributions that have been made for antimonide-based TPV cells, and suggests additional studies for further performance enhancements.

With the advent of tabletop X-ray lasers that operate at high repetition rate more emphasis is being put on finding useful applications for these lasers. The 14.7 nm Ni-like Pd X-ray laser at Lawrence Livermore National Laboratory is being used to do many interferometer experiments. As detailed quantitative comparisons are done between experiments and code simulations it is clear that some of the assumptions used to analyze the experiments need to be modified as one explores plasmas that are only a few times ionized. In the case of aluminium plasmas that have been analyzed with interferometers there has been some unusual behavior where the fringe lines bend the wrong way. In this work we will discuss how the index of refraction for aluminium is far more complicated than generally assumed because there are significant contributions to the index from the continuum and line structure of the bound electrons that can dominate the free electron contribution and even cause the index to be greater than one. We will also discuss some potential applications of the high repetition rate Ne-like Ar X-ray laser at 46.9 nm. In particular we will present modeling that shows how the Ar laser could be used to …

Weekly newspaper from Holliday, Texas that includes local, state, and national news along with advertising.

Daily newspaper from Baytown, Texas that includes local, state, and national news along with advertising.

The large cable programmers, who provide most of the popular cable (and broadcast) television programming, respond that a single large expanded basic service tier represents the most efficient way to offer programming and that allowing customers to obtain networks on an a la carte basis or in small tiers would raise costs – and hence prices to consumers – and also reduce the diversity of programs offered, so that consumer welfare would suffer in the long run. In this report, the pros and cons of offering subscribers only a single large expanded basic service tier and also of the various proposals to provide consumers more options are presented.

Weekly newspaper from Rusk, Texas that includes local, state and national news along with extensive advertising.

Prior to the recent commissioning of the first NIF (National Ignition Facility) beamline, full-scale laser-amplifier-glass cleanliness experiments were performed. Aerosol measurements and obscuration data acquired using a modified flatbed scanner compare favorably to historical large-scale lasers and indicate that NIF is the cleanest large-scale laser built to date.

Climate change and greenhouse gas (GHG) emissions have been an issue in the 108th Congress, as they have been over the past decade. Bills directly addressing climate change issues range from those focused primarily on climate change research (H.R. 1578 and S. 1164) to comprehensive emissions cap and trading programs for all six greenhouse gases (S. 139 and H.R. 4067). This report briefly discusses basic concepts on which these bills are based, and compares major provisions of the bills in each of the following categories: climate change research, GHG reporting and registries, and cap and trade programs.

Weekly newspaper from The Colony, Texas that includes local, state, and national news along with advertising.

Weekly newspaper from Cuero, Texas that includes local, state, and national news along with advertising.

The authors explore the feasibility of adding a performance option to DOE's EnergyStar{copyright} Windows program whereby windows of differing U-factors and SHGCs can qualify so long as they have equivalent annual energy performance. An iterative simulation procedure is used to calculate trade-off equations giving the change in SHGC needed to compensate for a change in U-factor. Of the four EnergyStar{copyright} Window climate zones, trade-off equations are possible only in the Northern and Southern zones. In the North/Central and South/Central zones, equations are not possible either because of large intrazone climate variations or the current SHGC requirements are already near optimum.

Testimony issued by the General Accounting Office with an abstract that begins "In November 2003, GAO testified on the significant level of improper premium class travel purchased with centrally billed accounts. These findings led to concerns over the Department of Defense's (DOD) overall management of the centrally billed account program. At the request of this Committee, Senator Grassley, and Representative Schakowsky, GAO performed work to determine whether DOD controls were adequate to protect the centrally billed accounts from fraud, waste, and abuse. This testimony focuses on whether DOD (1) paid for airline tickets that it did not use and did not process for refund, (2) improperly reimbursed travelers for the cost of airline tickets paid for with centrally billed accounts, and (3) adequately secured access to centrally billed accounts against improper and fraudulent use. This testimony also addresses the internal control breakdowns that led to instances of fraud, waste, and abuse and DOD's corrective actions. In two companion reports issued today, DOD concurred with the 31 recommendations GAO made-- including moving to a well- managed individually billed account program--to improve the management of unused tickets, recover the value of outstanding unused tickets, prevent and detect improper payments, reduce the risk …

A letter report issued by the General Accounting Office with an abstract that begins "Ineffective management and oversight of the Department of Defense's (DOD) premium class travel and unused airline tickets led to concerns about DOD's overall management of the centrally billed accounts. GAO was asked to determine whether (1) DOD improperly reimbursed travelers for airline tickets DOD paid for using centrally billed accounts, (2) internal controls were effective in preventing issuance of unauthorized airline tickets, and (3) other control weaknesses led to compromised and fraudulently used centrally billed accounts."

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Sputtered Be shells are made by sputter deposition of Be, with a radially graded Cu dopant as necessary, onto plastic mandrels supplied by General Atomics. Although the plastic mandrel may not be a design issue, it is a fielding issue because at cryo temperatures the plastic shrinks more than the Be and delaminates. We described in previous memos a proposed method for thermally removing the plastic by burning it in air at elevated temperature. A key aspect to this process is getting air in and out of the shell through the small diameter hole that must be laser drilled in the capsule wall to serve as a fill hole for the fuel. Because the hole is quite small, gas flow through the orifice must be forced, and an external pressure variation was suggested to do this. Further calculations showed that since the volume of the capsule is quite small and the amount of plastic in the shell by comparison is large, the ''pumping'' of air in and out of the shell must occur at least once per minute in order to supply enough O{sub 2} to completely burn the plastic to CO{sub 2} and H{sub 2}O in a reasonable time. …

Daily newspaper from Chickasha, Oklahoma that includes local, state, and national news along with advertising.

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Final report on conference grant supporting the American Physical Society Division of Particles and Fields meeting in Philadlephia, PA April 5-8, 2003.

The International Conference on Charged Particle Optics, CPO, is held every 4 years, and brings together scientists working in all areas of charged-particle optics including electron microscopy, accelerators, spectrometers, electron and ion sources, and theory. In October 2002 the sixth such conference, CPO6, was held near Washington, DC. This is the report on the Sixth International Charged-Particle Optics Conference. Proceedings of this conference have been published in Nuclear Instruments & Methods in Physics Research, Section A Volume 519, February/March 2004.