Direct numerical methods for solving the Vlasov equationoffer some advantages over macroparticle simulations, as they do notsuffer from the consequences of the statistical fluctuations inherent inusing a number of macroparticles smaller than thebunch population.Unfortunately these methods are more time-consuming and generallyconsidered impractical in a full 6D phase space. However, in alower-dimension phase space they may become attractive if the beamdynamics is sensitive to the presence of small charge-densityfluctuations and a high resolution is needed. In this paper we present a2D Vlasov solverfor studying the longitudinal beam dynamics insingle-pass systems of interest for X-Ray FELs, where characterization ofthe microbunching instability stemming from self-field amplified noise isof particular relevance.

Adaptive Mesh Refinement (AMR) is a highly effective method for simulations that span a large range of spatiotemporal scales, such as astrophysical simulations that must accommodate ranges from interstellar to sub-planetary. Most mainstream visualization tools still lack support for AMR as a first class data type and AMR code teams use custom built applications for AMR visualization. The Department of Energy's (DOE's) Science Discovery through Advanced Computing (SciDAC) Visualization and Analytics Center for Enabling Technologies (VACET) is currently working on extending VisIt, which is an open source visualization tool that accommodates AMR as a first-class data type. These efforts will bridge the gap between general-purpose visualization applications and highly specialized AMR visual analysis applications. Here, we give an overview of the state of the art in AMR visualization research and tools and describe how VisIt currently handles AMR data.

Renewables portfolio standards (RPS) have--since the late 1990s--proliferated at the state level in the United States. What began as a policy idea minted in California and first described in detail in the pages of the 'Electricity Journal' FPT has emerged as an important driver for renewable energy capacity additions in the United States. Over the years, articles in the 'Electricity Journal' have explored the RPS in more detail, identifying both its strengths and weaknesses. The present article provides an introduction to the history, concept, and design of the RPS, reviews early experience with the policy as applied at the state level, and provides a brief overview of Federal RPS proposals to date and the possible relationship between Federal and state RPS policies. Our purpose is to offer a factual introduction to the RPS, as applied and considered in the U.S. Though elements of state RPS design are summarized here, other publications provide a more thorough review of design lessons that emerge from that experience. In addition, the present article does not describe the results of economic analyses of Federal RPS proposals, though we do cite many of the analyses conducted by the U.S. DOE's Energy Information Administration (EIA).

As flight speed increases, aerodynamic drag rises more sharply than the availability of atmospheric oxygen. The ratio of oxygen mass flux to dynamic pressure cannot be improved by changing altitude. The maximum possible speed for airbreathing propulsion is limited by the ratio of air capture area to vehicle drag area, approximately Mach 6 at equal areas. Simulation of vehicle acceleration shows that the use of atmospheric oxygen offers a significant potential for minimizing onboard consumables at low speeds. These fundamental calculations indicate that a practical airbreathing launch vehicle would accelerate to near steady-state speed while consuming only onboard fuel, then transition to rocket propulsion. It is suggested that an aircraft carrying a rocket-propelled vehicle to approximately Mach 5 could be a realistic technical goal toward improving access to orbit.

Returning Mars geology samples to Earth within science mission budgets requires a miniature launch vehicle (100-200 kg) for ascending from Mars to an orbital rendezvous. A Mars Ascent Vehicle must deliver a velocity change exceeding 4 km/s within minutes, entirely outside the capabilities of satellite propulsion. A possible solution is to scale down liquid launch vehicle principles to achieve stage propellant mass fractions near 90 percent. Feeding a high-pressure engine from thin-walled low pressure tanks permits stage hardware to be sufficiently lightweight and compact, if very high performance pumps can be made available. NASA's Mars Technology Program has funded refinement and testing of a miniature piston pump, powered by reacted propellant. A pump-fed bipropellant rocket stage remains to be developed. The technology could also benefit other future lunar and planetary science programs.

The family of R{sub 5}Si{sub x}Ge{sub 4-x} alloys demonstrates a variety of unique physical phenomena related to magneto-structural transitions associated with reversible breaking and reforming of specific bonds that can be controlled by numerous external parameters such as chemical composition, magnetic field, temperature, and pressure. Therefore, R{sub 5}Si{sub x}Ge{sub 4-x} systems have been extensively studied to uncover the mechanism of the extraordinary magneto-responsive properties including the giant magnetoresistance (GMR) and colossal magnetostriction, as well as giant magnetocaloric effect (GMCE). Until now, more than a half of possible R{sub 5}Si{sub x}Ge{sub 4-x} pseudobinary systems have been completely or partially investigated with respect to their crystallography and phase relationships (R = La, Pr, Nd, Gd, Tb, Dy, Er, Lu, Y). Still, there are other R{sub 5}Si{sub x}Ge{sub 4-x} systems (R = Ce, Sm, Ho, Tm, and Yb) that are not studied yet. Here, we report on phase relationships and structural, magnetic, and thermodynamic properties in the Yb{sub 5}Si{sub x}Ge{sub 4-x} and Sm{sub 5}Si{sub x}Ge{sub 4-x} pseudobinary systems, which may exhibit mixed valence states. The crystallography, phase relationships, and physical properties of Yb{sub 5}Si{sub x}Ge{sub 4-x} alloys with 0 {le} x {le} 4 have been examined by using single crystal and powder x-ray …

This report provides a status of the progress made in Fiscal Year 2006 on tasks identified in the Waste Area Group 10, Operable Unit 10-08, Remedial Investigation/Feasibility Study Work Plan. Major accomplishments include: (1) groundwater sampling and review of the groundwater monitoring data, (2) installation of a Sitewide groundwater-level monitoring network, (3) update of the Groundwater Monitoring and Field Sampling Plan of Operable Unit 10-08, (4) re-evaluation of the risk at Site TSF-08, (5) progress on the Operable Unit 10-08 Sitewide Groundwater Model.

The applicant proposes to design and synthesize a series of fluorine-18-labeled radiopharmaceuticals to be used as amyloid imaging agents for positron emission tomography (PET). The investigators will conduct comprehensive iterative in vitro and in vivo studies based upon well defined acceptance criteria in order to identify lead agents suitable for human studies. The long term goals are to apply the selected radiotracers as potential diagnostic agents of Alzheimer's disease (AD), as surrogate markers of amyloid in the brain to determine the efficacy of anti-amyloid therapeutic drugs, and as tools to help address basic scientific questions regarding the progression of the neuropathology of AD, such as testing the "amyloid cascade hypothesis" which holds that amyloid accumulation is the primary cause of AD.

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