We present for the first time, the self-consistent solution of the two-dimensional, time-dependent equations of radiation-hydrodynamics governing the accretion of matter onto the highly magnetized polar caps of luminous x-ray pulsars. The calculations show a structure in the accretion column very different from previous one-zone uniform models. We have included all the relevant magnetic field corrections to both the hydrodynamics and the radiative transport. We include a new theory for the diffusion and advection of both radiation energy density and photon number density. For initially uniformly accreting models with super-Eddington flows, we have uncovered evidence of strong radiation-driven outflowing optically thin radiation filled regions of the accretion column embedded in optically-thick inflowing plasma. The development of these photon bubbles'' have growth times on the order of a millisecond and show fluctuations on sub-millisecond timescales. The photon bubbles are likely to be a consequence of convective over-stability and may result in observable fluctuations in the emitted luminosity leading to luminosity dependent changes in the pulse profile. This may provide important new diagnostics for conditions in accreting x-ray pulsars. 13 refs., 18 figs.

Hadron masses are calculated on an 8/sup 3/ /times/ 16 lattice using four flavors of staggered fermion to generate the gauge configurations, but using Wilson fermions to calculate the hadron propagators. The identification of a value of the Wilson hopping parameter with the value of the bare quark mass used in the simulations is discussed.

Long-range as well as head-on beam-beam effects are expected to limit the LHC performance with design parameters. They are also important consideration for the LHC upgrades. To mitigate long-range effects current carrying wires parallel to the beam were proposed. Two such wires are installed in RHIC where they allow studying the effect of strong long-range beam-beam effects, as well as the compensation of a single long-range interaction. The tests provide benchmark data for simulations and analytical treatments. To reduce the head-on beam-beam effect electron lenses were proposed for both RIDC and the LHC. We present the experimental long-range beam-beam program at RHIC and report on head-on compensations studies based on simulations.

We present an extension of conventional laterally resolved soft x-ray photoelectron emission microscopy. A depth resolution along the surface normal down to a few {angstrom} can be achieved by setting up standing x-ray wave fields in a multilayer substrate. The sample is an Ag/Co/Au trilayer, whose first layer has a wedge profile, grown on a Si/MoSi2 multilayer mirror. Tuning the incident x-ray to the mirror Bragg angle we set up standing x-ray wave fields. We demonstrate the resulting depth resolution by imaging the standing wave fields as they move through the trilayer wedge structure.

Formic acid (HCOOH) is a convenient hydrogen carrier in fuel cells designed for portable use. Recent studies have shown that HCOOH decomposition is catalyzed with Ru-based complexes in the aqueous phase at near-ambient temperatures. HCOOH decomposition reactions are used frequently to probe the effects of alloying and cluster size and of geometric and electronic factors in catalysis. These studies have concluded that Pt is the most active metal for HCOOH decomposition, at least as large crystallites and extended surfaces. The identity and oxidation state of surface metal atoms influence the relative rates of dehydrogenation (HCOOH {yields} H{sub 2} + CO{sub 2}) and dehydration (HCOOH {yields} H{sub 2}O + CO) routes, a selectivity requirement for the synthesis of CO-free H{sub 2} streams for low-temperature fuel cells. Group Ib and Group VIII noble metals catalyze dehydrogenation selectively, while base metals and metal oxides catalyze both routes, either directly or indirectly via subsequent water-gas shift (WGS) reactions.

Instabilities with frequencies in the neighborhood of the electron cyclotron frequency are of interest in determining stable operating regimes of hot-electron plasmas in EBT devices and in tandem mirrors. Previous work used model distributions significantly different than those suggested by recent Fokker-Planck studies. We use much more realistic model distributions in a computer code that solves the full electromagnetic dispersion relation governing longitudinal and transverse waves in a uniform plasma. We allow for an arbitrary direction of wave propagation. Results for the whistler and upper-hybrid loss-cone instabilities are presented.

The energy-dispersive x-ray fluorescence analysis (XRFA) technique has been implemented at several spent nuclear fuel reprocessing facilities for nondestructive measurements of uranium and/or plutonium concentrations in process streams and product storage tanks. An important factor in these quantitative measurements is the absorption of the fluoresced x-rays by the solution matrix, which must be taken into account to accurately quantify the U or Pu concentrations. We describe a new, accurate method using a dual transmission source of Gd-153 and Co-57 to correct for matrix effects. Results of measurements on uranium and plutonium solution standards show the methodology to be better than 0.5%, which includes statistical precision, over the concentration range from 1 to 250 g/l. 5 refs., 4 figs., 3 tabs.

We present a new construction of wavelets on arbitrary two-manifold topology for geometry compression. The constructed wavelets generalize symmetric tensor product wavelets with associated B-spline scaling functions to irregular polygonal base mesh domains. The wavelets and scaling functions are tensor products almost everywhere, except in the neighborhoods of some extraordinary points (points of valence unequal four) in the base mesh that defines the topology. The compression of arbitrary polygonal meshes representing isosurfaces of scalar-valued trivariate functions is a primary application. The main contribution of this paper is the generalization of lifted symmetric tensor product B-spline wavelets to two-manifold geometries. Surfaces composed of B-spline patches can easily be converted to this scheme. We present a lossless compression method for geometries with or without associated functions like color, texture, or normals. The new wavelet transform is highly efficient and can represent surfaces at any level of resolution with high degrees of continuity, except at a finite number of extraordinary points in the base mesh. In the neighborhoods of these points detail can be added to the surface to approximate any degree of continuity.

Bremstrahlung Isochromat Spectroscopy (BIS). The XES spectra were collected using a Specs electron gun for the excitation and the XES 350 grating monochromator and channel plate system from Scienta as the photon detection. Spectra were collected in 'normal mode,' where the electron gun kinetic energy (KE) and the energy position of the center of the channel plate were both fixed and the energy distribution in the photon (hv) spectrum was derived from the intensities distributed across the channel plate detector in the energy dispersal direction. The polycrystalline Ce sample was oxidized by exposure to air at ambient pressures. After introduction to the ultra-high vacuum system, the oxidized sample was bombarded with Ar, to clean the topmost surface region and stabilize the surface and near surface regions. Although CeO{sub 2} would be the thermodynamically preferred composition in an oxygen rich environment, the combination of a vacuum environment and ion etching may have driven the near surface region into a Ce{sub 2}O{sub 3} stoichiometry. XES data collection occurred with the sample at or near room temperature. The base pressure of the system was 3 x 10{sup -10} torr, but the pressure changed depending the energy and current of the electron gun. For …

The U.S. Department of Energy (DOE) recently completed a rulemaking process in which it amended the existing energy efficiency standards for residential water heaters. A key factor in DOE?s consideration of new standards is the economic impacts on consumers. Determining such impacts requires a comparison of the additional first cost of energy efficiency design options with the savings in operating costs. This paper describes the method used to conduct the life-cycle cost (LCC) and payback period analysis for gas and electric storage water heaters. It presents the estimated change in LCC associated with more energy-efficient equipment, including heat pump electric water heaters and condensing gas water heaters, for a representative sample of U.S. homes. The study included a detailed accounting of installation costs for the considered design options, with a focus on approaches for accommodating the larger dimensions of more efficient water heaters. For heat pump water heaters, the study also considered airflow requirements, venting issues, and the impact of these products on the indoor environment. The results indicate that efficiency improvement relative to the baseline design reduces the LCC in the majority of homes for both gas and electric storage water heaters, and heat pump electric water heaters and …

Among the different theoretical approaches able to describe fission, microscopic ones can help us in the understanding of this process, as they have the advantage of describing the nuclear structure and the dynamics in a consistent manner. The sole input of the calculations is the nucleon-nucleon interaction. Such a microscopic time-dependent and quantum mechanical formalism has already been used, based on the Gaussian Overlap Approximation of the Generator Coordinate Method with the adiabatic approximation, to analyze the collective dynamics of low-energy fission in {sup 238}U. However, at higher energies, a few MeV above the barrier, the adiabatic approximation doesn't seem valid anymore. Indeed, manifestations of proton pair breaking have been observed in {sup 238}U and {sup 239}U for an excitation energy of 2.3 MeV above the barrier. Taking the intrinsic excitations into account during the fission process will enable us to determine the coupling between collective and intrinsic degrees of freedom, in particular from saddle to scission. Guidelines of the new formalism under development are presented and some preliminary results on overlaps between non excited and excited states are discussed.

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Few engineering materials are limited by their strength; rather they are limited by their resistance to fracture or fracture toughness. It is not by accident that most critical structures, such as bridges, ships, nuclear pressure vessels and so forth, are manufactured from materials that are comparatively low in strength but high in toughness. Indeed, in many classes of materials, strength and toughness are almost mutually exclusive. In the first instance, such resistance to fracture is a function of bonding and crystal structure (or lack thereof), but can be developed through the design of appropriate nano/microstructures. However, the creation of tough microstructures in structural materials, i.e., metals, polymers, ceramics and their composites, is invariably a compromise between resistance to intrinsic damage mechanisms ahead of the tip of a crack (intrinsic toughening) and the formation of crack-tip shielding mechanisms which principally act behind the tip to reduce the effective 'crack-driving force' (extrinsic toughening). Intrinsic toughening is essentially an inherent property of a specific microstructure; it is the dominant form of toughening in ductile (e.g., metallic) materials. However, for most brittle (e.g., ceramic) solids, and this includes many biological materials, it is largely ineffective and toughening conversely must be developed extrinsically, by such …

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The susceptibility or Alloy 22 (N06022) to crevice corrosion may depend on environmental or external factors and metallurgical or internal factors. Some of the most important environmental factors are chloride concentration, inhibitors, temperature and potential. The presence of a weld seam or second phase precipitation in the alloy are classified as internal factors. The localized corrosion resistance of Alloy 22 has been extensively investigated in the last five years, however not all affecting factors were considered in the studies. This paper discusses the current findings regarding the effect of many of these variables on the susceptibility (or resistance) of Alloy 22 to crevice corrosion. The effect of variables such as temperature, chloride concentration and nitrate are rather well understood. However there are only limited or no data regarding effect of other factors such as pH, other inhibitive or deleterious species and type of crevicing material and crevice geometry. There are contradictory results regarding the effect of metallurgical factors such as solution heat treatment.

This paper presents the history of Professor T. D. Lee's seminal work on the theory of relativistic heavy ion collisions, and the founding and development of the Riken Brookhaven Center. A number of anecdotes are given about Prof. Lee, and his strong positive effect on his colleagues, particularly young physicists.

wxWindows is an Open Source, platform independent, User Interface (UI) which has been in development for over eleven years (http://www.wxwindows.org). Currently wxWindows is actively supported for the Linux/Unix (X11, Motif and GTK+), Mac OS 9 and X, all Win32 OSes, MGL, and OS/2 operating systems. wxWindows is written in C++ using an object oriented programming framework; it is a reasonably lightweight API (called wxWidgets) sitting over the native graphics packages of the various platforms it supports. The original version of CALE was written for the basic target platform of Unix using X11 as the graphics package. There have been separate efforts to port the code to Mac OS 9, Mac OS X, Win32, Windows Services for Unix (SFU) and CygWin. Each of these used a variety of different graphical interface approaches and build/make systems. For instance Windows SFU and CygWin could still only use X11 graphics. So could the Win32 version, if a X11 server library and client software were installed. A native Win32 version of CALE was contemplated, but never started. The Macintosh versions were completed but never widely distributed to the users. Given the growing code version support issues, and the slow deviation from the portable code model …

Methods for the numerical discretization of the Vlasov equation should efficiently use the phase space discretization and should introduce only enough numerical dissipation to promote stability and control oscillations. A new high-order, non-linear, finite-volume algorithm for the Vlasov equation that discretely conserves particle number and controls oscillations is presented. The method is fourth-order in space and time in well-resolved regions, but smoothly reduces to a third-order upwind scheme as features become poorly resolved. The new scheme is applied to several standard problems for the Vlasov-Poisson system, and the results are compared with those from other finite-volume approaches, including an artificial viscosity scheme and the Piecewise Parabolic Method. It is shown that the new scheme is able to control oscillations while preserving a higher degree of fidelity of the solution than the other approaches.

To predict the behavior of hydrate-bearing sediments and the economic extractability of natural gas from reservoirs containing gas hydrates, we need reservoir simulators that properly represent the processes that occur, as well as accurate parameters. Several codes are available that represent some or all of the expected processes, and values for some parameters are available. Where values are unavailable, modelers have used estimation techniques to help with their predictions. Although some of these techniques are well respected, measurements are needed in many cases to verify the parameters. We have performed a series of experiments in a partially water saturated silica sand sample. The series included methane hydrate formation, and dissociation by both thermal stimulation and depressurization. The sample was 7.6 cm in diameter and 25 cm in length. In addition to measuring the system pressure and temperatures at four locations in the sample, we measured local density within the sample using x-ray computed tomography. Our goals in performing the experiment were to gather information for estimating thermal properties of the medium and to examine nonequilibrium processes.

Researchers at the Department of Energy's Savannah River Technology Center are using advanced microscopy techniques to understand the effects of trace organic chemical additions on nuclear waste slurry flow properties. Trace organic chemicals, surfactants (rheology modifiers), are being used in all types of industries to modify the flow properties of various commercial chemicals. Nuclear waste treatment at the Department of Energy's weapons production facilities, Savannah River Site and Hanford Reservation, is limited by the viscosity of the nuclear waste slurries as the material is processed through a variety of waste treatment and immobilization processes. The picture was taken using a laser scanning confocal microscope.

Limited research is available on potential adverse effects of school environments on academic performance, despite strong public concern. We examine the scientific evidence relevant to this relationship by reviewing available research relating schools and other indoor environments to human performance or attendance. As a primary focus, we critically review evidence for direct relationships between indoor environmental quality (IEQ) in buildings and performance or attendance. As a secondary focus, we summarize, without critique, evidence on potential connections indirectly linking IEQ to performance or attendance: relationships between IEQ and health, between health and performance or attendance, and between attendance and performance. The most persuasive direct evidence showed increases in indoor concentrations of nitrogen dioxide and outdoor concentrations of several specific pollutants to be related to reduced school attendance. The most persuasive indirect evidence showed indoor dampness and microbiologic pollutants to be related to asthma and respiratory infections, which have in turn been related to reduced performance and attendance. Furthermore, a substantial scientific literature links poor IEQ (e.g., low ventilation rate, excess moisture or formaldehyde) with respiratory and other health effects in children and adults. Overall, evidence suggests that poor IEQ in schools can influence the performance and attendance of students, primarily through …

Increased biomass burning (e.g., forest fires, controlled burns, etc.) and anthropogenic emissions into the earth's atmosphere in the past century have led to much debate with regard to greenhouse gases, atmospheric carbon buildup, aerosol increases, and global warming. Atmospheric aerosols are linked to reduced air quality and visibility (V) in many parts of the world. In south-central South Carolina visibility reduction has been responsible for traffic fatalities on public highways, with resulting lawsuits against governmental entities. Congress passed the Clean Air Act in 1963, with amendments in 1970, 1977, and 1990 to improve air quality. The actual implementation of the Clean Air Act has been an intermittent process because of litigation over some provisions of the Act. However, it is reasonable to assume that visibility has improved in the U.S. over the past decades due to implementation of the Clean Air Act's provisions. In this study visibility data have been acquired for seven weather stations along or near the U.S. East Coast to study how conditions have changed from the 1980s to the 1990s.

The processing rate of Savannah River Site high level waste decontamination processes are limited by the flow rate of the solid-liquid separation. The baseline process, using a 0.1 micron cross flow filter, produces 0.02 gpm/ft2 of filtrate under expected operating conditions. Savannah River National Laboratory personnel identified the rotary microfilter as a technology that could significantly increase filter flux, with throughput improvements of as much as 10X for that specific operation. With funding from the Department of Energy Office of Cleanup Technologies, SRNL personnel are evaluating and developing the rotary microfilter for radioactive service at SRS. This work includes pilot-scale and actual waste testing to evaluate system reliability, the impact of radiation on system components, the filter flux for a variety of waste streams, and relative performance for alternative filter media.

We investigate the appearance of closed timelike curves in quotients of plane waves along spacelike isometries. First we formulate a necessary and sufficient condition for a quotient of a general spacetime to preserve stable causality. We explicitly show that the plane waves are stably causal; in passing, we observe that some pp-waves are not even distinguishing. We then consider the classification of all quotients of the maximally supersymmetric ten-dimensional plane wave under a spacelike isometry, and show that the quotient will lead to closed timelike curves iff the isometry involves a translation along the u direction. The appearance of these closed timelike curves is thus connected to the special properties of the light cones in plane wave spacetimes. We show that all other quotients preserve stable causality.