The authors use the relativistic hydrodynamics code Cosmos++ to model the evolution of the radio nebula triggered by the Dec. 27, 2004 giant flare event of soft gamma repeater 1806-20. They primarily focus on the rebrightening and centroid motion occurring subsequent to day 20 following the flare event. They model this period as a mildly relativistic ({gamma} {approx} 1.07-1.67) jetted outflow expanding into the intergalactic medium (IGM). They demonstrate that a jet with total energy {approx} 10{sup 46} ergs confined to a half opening angle {approx} 20{sup o} fits the key observables of this event, e.g. the flux lightcurve, emission map centroid position, and aspect ratio. In particular, they find excellent agreement with observations if the rebrightening is due to the jet, moving at 0.5 c and inclined {approx} 0{sup o}-40{sup o} toward the observer, colliding with a density discontinuity in the IGM at a radius of several 10{sup 16} cm. They also find that a jet with a higher velocity, {approx}> 0.7c, and larger inclination, {approx}> 70{sup o}, moving into a uniform IGM can fit the observations in general, but tends to miss the details of rebrightening. The latter, uniform IGM model predicts an IGM density more than 100 …

Correspondence issued by the Government Accountability Office with an abstract that begins "Securing the U.S. border has received increasing attention since the terrorist attacks of September 11, 2001. For years, U.S. and Canadian citizens have crossed the northern border using documents such as driver's licenses or birth certificates or in some cases without showing any documentation. Border crossings are commonplace; in 2005, for example, an estimated 13 million U.S. citizens crossed the northern border. In the heightened national security environment after September 11, we have previously reported that documents like driver's licenses and birth certificates can easily be obtained, altered, or counterfeited and used by terrorists to travel into and out of the country. The Intelligence Reform and Terrorism Prevention Act of 2004 requires the Secretary of Homeland Security, in consultation with the Secretary of State, to develop and implement a plan that requires a passport or other document or combination of documents that the Secretary of Homeland Security deems sufficient to show identity and citizenship for U.S. citizens and citizens of Bermuda, Canada, and Mexico when entering the United States from certain countries in North, Central, or South America. The act requires the Department of Homeland Security (DHS) and …

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This report details information such as history and analyses of renewable energy tax credit, budget, and electricity production issues.

A comprehensive study on the relationship between yield strength, relative density and ligament sizes is presented for nanoporous Au foams. Depth-sensing nanoindentation tests were performed on nanoporous foams ranging from 20 to 42% relative density with ligament sizes ranging from 10 to 900 nm. The Gibson and Ashby yield strength equation for open-cell macro-cellular foams is modified in order to incorporate ligament size effects. This study demonstrates that at the nanoscale, foam strength is governed by ligament size, in addition to relative density. Furthermore, we present the ligament length scale as a new parameter to tailor foam properties and achieve high strength at low densities.

This month's issue has the following articles: (1) Experiments at the Scale of Simulations--Commentary by Tomas Diaz de la Rubia; (2) A New Realm of Materials Science--Livermore scientists are combining experiment, theory, and simulation to study the response of solids to extreme dynamic stresses at nanometer and subnanosecond scales; (3) Planets and Stars under the Magnifying Glass--An international collaboration involving Laboratory scientists has discovered a planet made of rock or ice orbiting a dim star outside our solar system; and (4) Keeping an Eye on the Prize--A Livermore-IBM team uses a new code and the world's fastest computer to set a performance record for a science application.

Quarterly publication of the Texas Comptroller's Office regarding sales and use tax in the state of Texas, including an analysis by county, analysis by industry, and related notes.

In the last few years, SAXS of biological materials has been rapidly evolving and promises to move structural analysis to a new level. Recent innovations in SAXS data analysis allow ab initio shape predictions of proteins in solution. Furthermore, experimental scattering data can be compared to calculated scattering curves from the growing data base of solved structures and also identify aggregation and unfolded proteins. Combining SAXS results with atomic resolution structures enables detailed characterizations in solution of mass, radius, conformations, assembly, and shape changes associated with protein folding and functions. SAXS can efficiently reveal the spatial organization of protein domains, including domains missing from or disordered in known crystal structures, and establish cofactor or substrate-induced conformational changes. For flexible domains or unstructured regions that are not amenable for study by many other structural techniques, SAXS provides a unique technology. Here, we present SAXS shape predictions for PCNA that accurately predict a trimeric ring assembly and for a full-length DNA repair glycosylase with a large unstructured region. These new results in combination with illustrative published data show how SAXS combined with high resolution crystal structures efficiently establishes architectures, assemblies, conformations, and unstructured regions for proteins and protein complexes in solution.

Superconducting high resolution fast-neutron calorimetric spectrometers based on {sup 6}LiF and TiB{sub 2} absorbers have been developed. These novel cryogenic spectrometers measure the temperature rise produced in exothermal (n, {alpha}) reactions with fast neutrons in {sup 6}Li and {sup 10}B-loaded materials with heat capacity C operating at temperatures T close to 0.1 K. Temperature variations on the order of 0.5 mK are measured with a Mo/Cu thin film multilayer operated in the transition region between its superconducting and its normal state. The advantage of calorimetry for high resolution spectroscopy is due to the small phonon excitation energies k{sub B}T on the order of {mu}eV that serve as signal carriers, resulting in an energy resolution {Delta}E {approx} (k{sub B}T{sup 2}C){sup 1/2}, which can be well below 10 keV. An energy resolution of 5.5 keV has been obtained with a Mo/Cu superconducting sensor and a TiB{sub 2} absorber using thermal neutrons from a {sup 252}Cf neutron source. This resolution is sufficient to observe the effect of recoil nuclei broadening in neutron spectra, which has been related to the lifetime of the first excited state in {sup 7}Li. Fast-neutron spectra obtained with a {sup 6}Li-enriched LiF absorber show an energy resolution of 16 …

Testimony issued by the Government Accountability Office with an abstract that begins "The Office of Personnel Management (OPM) administers the annual Combined Federal Campaign (CFC), which gave more than 22,000 charities access to the federal workplace, helping those in need by collecting more than $250 million in donations during the 2005 campaign. The success of the campaign is predicated on each donor's confidence in a system that ensures donations reach charitable organizations that have met the CFC's specific eligibility requirements and are legitimate charities. For example, to be eligible, each charity must have formally received from the Internal Revenue Service (IRS) tax-exemption designation under 501(c)(3) of the Internal Revenue Code. The Subcommittee on Oversight is reviewing tax-exempt status entities and asked GAO to determine whether charitable organizations participating in the CFC were remitting their payroll and other taxes to the IRS as required by law. Specifically, GAO was asked to investigate and determine whether and to what extent (1) charities listed in the 2005 CFC have unpaid payroll and other taxes; (2) selected charities, their directors or senior officers are abusing the federal tax system; and (3) OPM screens charities for federal tax problems before allowing them to be listed …

Pentaerythritol tetranitrate (PETN) powders are used to initiate other explosives. During long-term storage, changes in powder properties can cause changes in the initiation performance. Changes in the morphology and surface area of aging powders are observed due to sublimation and growth of PETN crystals through coarsening mechanisms, (e.g. Ostwald ripening, sintering, etc.). In order to alleviate the sublimation of PETN crystals under service conditions, stabilization methods such as thermal cycling and doping with certain impurities during or after the crystallization of PETN have been proposed. In this report we present our work on the effect of impurities on the morphology and activation energy of the PETN crystals. The pure and impurity doped crystals of PETN were grown from supersaturated acetone solution by solvent evaporation technique at room temperature. The difference in the morphology of the impurity-doped PETN crystal compared to pure crystal was examined by optical microscopy. The changes in the activation energies and the evaporation rates are determined by thermogravimetric (TGA) analyses. Our activation energies of evaporation agree with earlier reported enthalpies of vaporization. The morphology and activation energy of PETN crystals doped with Ca, Na, and Fe cations are similar to that for pure PETN crystal, whereas the …

This article describes how to accelerate the convergence of Preconditioned Conjugate Gradient (PCG) type eigensolvers for the computation of several states around the band gap of colloidal quantum dots. Our new approach uses the Hamiltonian from the bulk materials constituent for the quantum dot to design an efficient preconditioner for the folded spectrum PCG method. The technique described shows promising results when applied to CdSe quantum dot model problems. We show a decrease in the number of iteration steps by at least a factor of 4 compared to the previously used diagonal preconditioner.

A letter report issued by the Government Accountability Office with an abstract that begins "The Department of Veterans Affairs (VA) is responsible for determining that over 36,000 physicians working in its facilities have the appropriate professional credentials and qualifications to deliver health care to veterans. To do this, VA credentials and privileges physicians providing care at its medical facilities. In this report, GAO determined the extent to which selected VA facilities complied with (1) four VA credentialing requirements and five VA privileging requirements and (2) a requirement to submit information on paid malpractice claims. GAO also determined (3) whether VA has internal controls to help ensure the accuracy of information used to renew clinical privileges. GAO reviewed VA's policies, interviewed VA officials, and randomly sampled 17 physician files at each of seven VA medical facilities."

A letter report issued by the Government Accountability Office with an abstract that begins "In March 2004, GAO reported on gaps in VA's requirements for screening the professional credentials and personal backgrounds of health care practitioners (GAO-04-566). GAO found that VA's requirements did not ensure thorough screening of VA practitioners. VA concurred with four recommendations GAO made to improve practitioner screening. GAO was asked to determine the extent to which (1) VA has taken steps to improve practitioner screening by implementing GAO's recommendations and (2) VA facilities are in compliance with VA's practitioner screening requirements. GAO reviewed VA's current practitioner screening policies to determine if gaps remain, interviewed VA officials, and sampled about 60 practitioner files at each of seven VA facilities selected based on size and geographic location."

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