We review what is different and what is similar in a color superconductor as compared to an ordinary BCS superconductor. The parametric dependence of the zero-temperature gap, {phi}{sub 0}, on the coupling constant differs in QCD from that in BCS theory. On the other hand, the transition temperature to the superconducting phase, T{sub c}, is related to the zero-temperature gap in the same way in QCD as in BCS theory, T{sub c}/{phi}{sub 0} {approx_equal} 0.567.

In their recent paper, Djikpesse and Tarantola (Geophysics 65 (4) pp. 1023-1035, hereinafter D and T) raise a central question about geophysical inversion: how accurately must the physics of seismic waves in the Earth be modeled in order that inversion succeed? Two general criteria for successful inversion appear in D and T's discussion: fit of predicted to observed data, and prediction of Earth structure. The hypothesis underlying inversion is that these criteria are unextricably linked, so that data fit should lead to accurate inference of subsurface features. The authors have also worked on the data discussed in D and T, using different modeling choices and inversion algorithms but also achieving quite successful inversions, in both senses. They feel that a brief comparison of methods and results might highlight the subtle relation between accuracy in modeling and success in inversion as well as raising questions about the appropriateness of D and T's modeling and inversion choices.

The design of general-purpose dynamic load-balancing tools for parallel applications is more challenging than the design of static partitioning tools. Both algorithmic and software engineering issues arise. The authors have addressed many of these issues in the design of the Zoltan dynamic load-balancing library. Zoltan has an object-oriented interface that makes it easy to use and provides separation between the application and the load-balancing algorithms. It contains a suite of dynamic load-balancing algorithms, including both geometric and graph-based algorithms. Its design makes it valuable both as a partitioning tool for a variety of applications and as a research test-bed for new algorithmic development. In this paper, the authors describe Zoltan's design and demonstrate its use in an unstructured-mesh finite element application.

The authors report on the dc performance of the first GaN pnp bipolar junction transistor. The structure was grown by MOCVD on c-plane sapphire substrates and mesas formed by low damage Inductively Coupled Plasma etching with a Cl{sub 2}/Ar chemistry. The dc characteristics were measured up to V{sub BC} of 65 V in common base mode and at temperatures up to 250 C. Under all conditions, I{sub C} {approximately} I{sub E}, indicating higher emitter injection efficiency. The offset voltage was {le} 2 V and devices were operated up to power densities of 40kW{center{underscore}dot}cm{sup {minus}2}.

Very fine-grained Ni and Cu films were formed using pulsed laser deposition on fused silica substrates. The grain sizes in the films were characterized by electron microscopy, and the mechanical properties were determined by ultra-low load indentation, with finite-element modeling used to separate the properties of the layers from those of the substrate. Some Ni films were also examined after annealing to 350 and 450 C to enlarge the grain sizes. These preliminary results show that the observed hardnesses are consistent with a simple extension of the Hall-Petch relationship to grain sizes as small as 11 nm for Ni and 32 nm for Cu.

Non-vacuum electrodeposition and electroless deposition techniques with a potential to prepare large-area uniform precursor films using low-cost source materials and low-cost capital equipment are very attractive for the growth of compound materials for superconductors and photovoltaic applications. In the first part, a low-cost electrodeposition (ED) method will be discussed for fabrication of high-temperature Tl-oxide-based superconductors. In the second part, electrodeposition and electroless deposition of semiconductor Cu-In-Ga-Se thin films will be discussed.

The dynamics of low-x partons in the transverse plane of a high-energy nuclear collision is classical, and therefore admits a fully non-perturbative numerical treatment. The authors report results of a recent study estimating the initial energy density in the central region of a collision. Preliminary estimates of the number of gluons per unit rapidity, and the initial transverse momentum distribution of gluons, are also provided.

Phosphonate binding sites in guanidine and ammonium surface-functionalized silica xerogels were prepared via the molecular imprinting technique and characterized using solid state {sup 31}P MAS NMR. One-point, two-point, and non-specific host-guest interactions between phenylphosphonic acid (PPA) and the functionalized gels were distinguished by characteristic chemical shifts of the observed absorption peaks. Using solid state as well as solution phase NMR analyses, absorptions observed at 15.5 ppm and 6.5 ppm were identified as resulting from the 1:1 (one-point) and 2:1 (two-point) guanidine to phosphonate interactions, respectively. Similar absorptions were observed with the ammonium functionalized gels. By examining the host-guest interactions within the gels, the efficiency of the molecular imprinting procedure with regard to the functional monomer-to-template interaction could be readily assessed. Template removal followed by substrate adsorption studies conducted on the guanidine functionalized gels provided a method to evaluate the binding characteristics of the receptor sites to a phosphonate substrate. During these experiments, {sup 29}Si and {sup 31}P MAS NMR acted as diagnostic monitors to identify structural changes occurring in the gel matrix and at the receptor site from solvent mediated processes.

The authors discuss some recent developments in small x physics. Current understanding of small x physics is that pQCD works at HERA and the Tevatron, but perhaps even better than expected. There is much flexibility in parton distributions to hide interesting new effects. Indeed, there are strong hints from HERA that one is on the threshold of a new regime of truly high parton densities, where one may expect qualitative changes in the behavior of distributions.

MicroElectricalMechanical Systems (MEMS) were subjected to a vibration environment that had a peak acceleration of 120g and spanned frequencies from 20 to 2000 Hz. The device chosen for this test was a surface-micromachined microengine because it possesses many elements (springs, gears, rubbing surfaces) that may be susceptible to vibration. The microengines were unpowered during the test. The authors observed 2 vibration-related failures and 3 electrical failures out of 22 microengines tested. Surprisingly, the electrical failures also arose in four microengines in the control group indicating that they were not vibration related. Failure analysis revealed that the electrical failures were due to shorting of stationary comb fingers to the ground plane.

Investigation and evaluation of a complex system is often accomplished through the use of performance measures based on system response models. The response models are constructed using computer-generated responses supported where possible by physical test results. The general problem considered is one where resources and system complexity together restrict the number of simulations that can be performed. The levels of input variables used in defining environmental scenarios, initial and boundary conditions and for setting system parameters must be selected in an efficient way. This report describes an algorithmic approach for performing this selection.

Pre-and post-test analytical predictions of the dynamic behavior of a 1:10 scale model Reinforced Concrete Containment Vessel are presented. This model, designed and constructed by the Nuclear Power Engineering Corp., was subjected to seismic simulation tests using the high-performance shaking table at the Tadotsu Engineering Laboratory in Japan. A group of tests representing design-level and beyond-design-level ground motions were first conducted to verify design safety margins. These were followed by a series of tests in which progressively larger base motions were applied until structural failure was induced. The analysis was performed by ANATECH Corp. and Sandia National Laboratories for the US Nuclear Regulatory Commission, employing state-of-the-art finite-element software specifically developed for concrete structures. Three-dimensional time-history analyses were performed, first as pre-test blind predictions to evaluate the general capabilities of the analytical methods, and second as post-test validation of the methods and interpretation of the test result. The input data consisted of acceleration time histories for the horizontal, vertical and rotational (rocking) components, as measured by accelerometers mounted on the structure's basemat. The response data consisted of acceleration and displacement records for various points on the structure, as well as time-history records of strain gages mounted on the reinforcement. This paper …

The authors show that the most popular method to simulate Bose-Einstein (BE) interference effects predicts negligible correlations between identical pions originating from the hadronic decay of different W's produced in e{sup +}e{sup {minus}} {r_arrow} W{sup +}W{sup {minus}} {r_arrow} 4 jets at typical linear collider energies.

Liquid wall protection, which challenges chamber clearing, has such advantages it's Heavy Ion Fusion's (HIF) main line chamber design. Thin liquid protection from x rays is necessary to avoid erosion of structural surfaces and thick liquid makes structures behind 0.5 m of Flibe (7 mean free paths for 14 MeV neutrons), last the life of the plant. Liquid wall protection holds the promise of greatly increased economic competitiveness. Driver designers require {approx}200 beams to illuminate recent target designs from two sides. The illumination must be compatible with liquid wall protection. The ''best'' values for driver energy, gain, yield and pulse rate comes out of well-known trade-off studies. The chamber design is based on several key assumptions, which are to be proven before HIF can be shown to be feasible. The chamber R&D needed to reduce the unknowns and risks depend on resolving a few technical issues such as jet surface smoothness and rapid chamber clearing.

N-Reactor fuel constitutes almost 80% of the entire mass of the US Department of Energy's (DOE's) spent fuel inventory. The current plan for disposition of this fuel calls for interim dry storage, followed by direct repository disposal. However, this approach may not be viable for the entire inventory of N-Reactor fuel. The physical condition and chemical composition of much of the fuel have changed during the period that it has been in storage. The cladding of many of the fuel elements has been breached, allowing the metallic uranium fuel to react with water in the storage pools producing uranium oxides (U{sub x}O{sub y}) and uranium hydride (UH{sub 3}). Even if the breached fuel is placed in dry storage, it may continue to undergo significant changes caused by the reaction of exposed uranium with any remaining water in the container. Uranium oxides, uranium hydride, and hydrogen gas are expected to form as a result of this reaction. The presence of potentially explosive hydrogen and uranium hydride, which under certain conditions is pyrophoric, raises technical concerns that will need to be addressed. The electrometallurgical treatment process developed by Argonne National Laboratory (ANL) has potential for conditioning degraded N-Reactor fuel for long-term storage …

Recent experiments at the LLNL Petawatt Laser have demonstrated the generation of intense, high energy beams of electrons and ions from the interaction of ultra-intense laser light with solid targets. Focused laser intensities as high as 6 x 10{sup 20} W/cm{sup 2} are achieved, at which point the quiver energies of the target electrons extend to {approx}10 MeV. In this new, fully relativistic regime of laser-plasma interactions, nuclear processes become important and nuclear techniques are required to diagnose the high-energy particle production. In recent experiments we have observed electrons accelerated to 100 MeV, up to 60 MeV brehmsstrahlung generation, photo-nuclear fission and positron-electron pair creation. We also have observed monoenergetic jets of electrons having sufficiently small emittance to be interesting as a laser-accelerated beam, if the production mechanism could be understood and controlled. The huge flux of multi-MeV ponderomotively accelerated electrons produced in the laser-solid interaction is also observed to accelerate contaminant ions from the rear surface of the solid target up to 50 MeV. We describe spectroscopic measurements which reveal intense monoenergetic beam features in the proton energy spectrum. The total spectrum contains >10{sup 13} protons, while the monoenergetic beam pulses contain {approx}1 nC of protons, and exhibits a …

This engineering feasibility study compared three possible technical options and their economic viability of processing plutonium-bearing sludges containing 0.6 MT of weapons-grade Pu accumulated at the Mining and Chemical Combine (MCC) at Krasnoyarsk. In Option 1, the baseline, the sludges are processed by extraction and purification of plutonium for storage using existing technologies, and the non-soluble radioactive residues generated in these processes undergo subsequent solidification by cementation. Options 2 and 3 involve the direct immobilization of plutonium-bearing sludges into a solid matrix (without any Pu extraction) using a microwave solidification process in a metal crucible to produce a glass, which is boron-silicate in Option 2 and phosphate glass in Option 3. In all three options, the solid radioactive waste end products will be placed in storage for eventual geologic disposal. Immobilization of residual plutonium into glass-like matrices provides both safer storage over the lifetime of the radionuclides and greater security against unauthorized access to stored materials than does the extraction and concentration of PuO{sub 2}, supporting our efforts toward non-proliferation of fissile materials. Although immobilization in boron-silicate glass appears now to be marginally preferable compared to the phosphate glass option, a number of technical issues remain to be assessed by …

The changes in hydrogen bonding at the interface of silica-reinforced polysiloxane composites due to aging in gamma radiation environments were examined in this study. Solvent swelling was utilized to determine the individual contributions of the matrix polymer and polymer-filler interactions to the overall crosslink density. The results show how the polymer-filler hydrogen bonding dominates the overall crosslink density of the material. Air irradiated samples displayed decreased hydrogen bonding at the polymer-filler interface, while vacuum irradiation revealed the opposite effect.

An important application of seismic and acoustic unattended ground sensors (UGS) is the estimation of the three dimensional position of an emitting target. Seismic and acoustic data derived from UGS systems provide the taw information to determine these locations, but can be processed and analyzed in a number of ways using varying amounts of auxiliary information. Processing methods to improve arrival time picking for continuous wave sources and methods for determining and defining the seismic velocity model are the primary variables affecting the localization accuracy. Results using field data collected from an underground facility have shown that using an iterative time picking technique significantly improves the accuracy of the resulting derived target location. Other processing techniques show little advantage over simple crosscorrelation along in terms of accuracy, but may improve the ease with which time picks can be made. An average velocity model found through passive listening or a velocity model determined from a calibration source near the target source both result in similar location accuracies, although the use of station correction severely increases the location error.

The author discusses two variations on the completeness theme in atomic modeling: missing lines as they affect the performance of spectral synthesis codes, and missing configurations as they affect the theoretical emissivities of bright lines, with emphasis on the latter. It is shown that the detrimental effects of working with incomplete atomic models can overshadow those brought about by working with less-than-perfect atomic rates. Atomic models can be brought up to an acceptable level of completeness in a fairly straightforward manner, and on a reasonably short timescale, whereas the long-term goal of comprehensive accuracy is unlikely to be reached on the timescale of the current generation of X-ray observatories. A near-term, albeit imperfect, solution is to hybridize atomic models used to synthesize spectra. A hybrid atomic model is one for which a large-scale atomic model, in which completeness is achieved at the expense of accuracy, is augmented with more accurate atomic quantities as they become available.

The rapid advancement of computational capability including speed and memory size has prompted the wide use of computational fluid dynamics (CFD) codes to simulate complex flow systems. CFD simulations are used to study the operating problems encountered in system, to evaluate the impacts of operation/design parameters on the performance of a system, and to investigate novel design concepts. CFD codes are generally developed based on the conservation laws of mass, momentum, and energy that govern the characteristics of a flow. The governing equations are simplified and discretized for a selected computational grid system. Numerical methods are selected to simplify and calculate approximate flow properties. For turbulent, reacting, and multiphase flow systems the complex processes relating to these aspects of the flow, i.e., turbulent diffusion, combustion kinetics, interfacial drag and heat and mass transfer, etc., are described in mathematical models, based on a combination of fundamental physics and empirical data, that are incorporated into the code. CFD simulation has been applied to a large variety of practical and industrial scale flow systems.

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Fundamental metallurgical aspects of axial splitting in irradiated Zircaloy cladding have been investigated by microstructural characterization and analytical modeling, with emphasis on application of the results to understand high-burnup fuel failure under RIA situations. Optical microscopy, SEM, and TEM were conducted on BWR and PWR fuel cladding tubes that were irradiated to fluence levels of 3.3 x 10{sup 21} n cm{sup {minus}2} to 5.9 x 10{sup 21} n cm{sup {minus}2} (E > 1 MeV) and tested in hot cell at 292--325 C in Ar. The morphology, distribution, and habit planes of macroscopic and microscopic hydrides in as-irradiated and posttest cladding were determined by stereo-TEM. The type and magnitude of the residual stress produced in association with oxide-layer growth and dense hydride precipitation, and several synergistic factors that strongly influence axial-splitting behavior were analyzed. The results of the microstructural characterization and stress analyses were then correlated with axial-splitting behavior of high-burnup PWR cladding reported for simulated-RIA conditions. The effects of key test procedures and their implications for the interpretation of RIA test results are discussed.

The author begins by discussing the history of nuclear power development in the US. He discusses the challenges for nuclear power such as the proliferation of weapons material, waste management, economics, and safety. He then discusses the future for nuclear power, specifically advanced reactor development. People can all be thankful for nuclear power, for it may well be essential to the long term survival of civilization. Within the seeds of its potential for great good, are also the seeds for great harm. People must ensure that it is applied for great good. What is not in question is whether people can live without it, they cannot. United States leadership is crucial in determining how this technology is developed and applied. The size and capability of the United States technical community is decreasing, a trend that cannot be allowed to continue. It is the author's belief that in the future, the need, the vision and the confidence in nuclear power will be restored, but only if the US addresses the immediate challenges. It is a national challenge worthy of the best people this nation has to offer.