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This article discusses dynamics of electroencephalogram entropy and pitfalls of scaling detection. Herein the authors study the time evolution of diffusion entropy to elucidate the scaling of EGG time series.

Pendeo-epitaxy has been applied to nonpolar a-plane GaN layers in order to observe if such process will lead to defect reduction in comparison with direct growth on this plane. Uncoalesced and coalesced a-plane GaN layers with thicknesses 2{micro}m and 12{micro}m, respectively have been studied by conventional and high resolution electron microscopy. The following structural defects have been observed in pendeo-epitaxial layers: (1) basal stacking faults, (2) threading dislocations and (3) prismatic stacking faults. Drastic decrease of threading dislocation density and stacking faults have been observed in 'wing' areas with respect to 'seed' areas. Cross-section images reveal cracks and voids at the areas where two coalesced wings meet each other. High resolution electron microscopy shows that the majority of stacking faults are low-energy planar defects of the types I{sub 1}, I{sub 2} and I{sub 3}. The I{sub 3} type basal stacking fault, predicted theoretically, has been observed experimentally for the first time.

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A 1D model of space-charge impedance, assuming atransversely uniform beam with circular cross-section, has been proposedand is being extensively used in the modelling of the microbunchinginstability of relevance for the beam delivery systems of x-ray FELs. Inthis paper we investigate the limitation of the model when applied tostudying the effect of shot noise--one of the sources of themicrobunching instability. We make comparison witha fully 3D calculationand identify the upper end of the frequency spectrum for applicability ofthe 1D model. Relaxation of the assumptions regarding axis-symmetry anduniformity of the transverse density is also reviewed.

A crucial step in human breast cancer progression is the acquisition of invasiveness. There is a distinct lack of human cell culture models to study the transition from pre-invasive to invasive phenotype as it may occur 'spontaneously' in vivo. To delineate molecular alterations important for this transition, we isolated human breast epithelial cell lines that showed partial loss of tissue polarity in three-dimensional reconstituted-basement membrane cultures. These cells remained non-invasive; however, unlike their non-malignant counterparts, they exhibited a high propensity to acquire invasiveness through basement membrane in culture. The genomic aberrations and gene expression profiles of the cells in this model showed a high degree of similarity to primary breast tumor profiles. The xenograft tumors formed by the cell lines in three different microenvironments in nude mice displayed metaplastic phenotypes, including squamous and basal characteristics, with invasive cells exhibiting features of higher grade tumors. To find functionally significant changes in transition from pre-invasive to invasive phenotype, we performed attribute profile clustering analysis on the list of genes differentially expressed between pre-invasive and invasive cells. We found integral membrane proteins, transcription factors, kinases, transport molecules, and chemokines to be highly represented. In addition, expression of matrix metalloproteinases MMP-9,-13,-15,-17 was up regulated …

The physical and electrochemical properties of LixMnO2 and LixTi0.11Mn0.89O2 synthesized from precursors made by glycine-nitrate combustion (GNC) and solid-state synthesis methods (SS) are examined in this paper. The highest specific capacities in lithium cells are obtained for SS-LixMnO2 electrodes at low current densities, but GNC-LixTi0.11Mn0.89O2 electrodes show the best high rate performance. These results can be explained by changes in the voltage characteristics and differences in the particle morphologies induced by the Ti-substitution and synthesis method. Ti-substitution also results in a decrease in the electronic conductivity, but greatly improves the thermal properties and imparts dissolution resistance to the electrode. For these reasons, it is preferable to use LixTi0.11MnO0.89O2 in lithium battery configurations rather than LixMnO2. Suggestions for improving the electrochemical performance of the Ti-substituted variant are given based on the results described herein.

When a networked polymeric composite under high stress is subjected to irradiation, the resulting chemical changes like chain scissioning and cross-link formation can lead to permanent set and altered elastic modulus. Using a commercial silicone elastomer as a specific example we show that a simple 2-stage Tobolsky model in conjunction with Fricker's stress-transfer function can quantitatively reproduce all experimental data as a function of radiation dosage and the static strain at which radiation is turned on, including permanent set, stress-strain response, and net cross-linking density.

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Molecular dynamics is employed to study the low energy states of a beam of charged particles subject to circumferentially varying guiding and focusing forces and with Coulomb forces between the particles. In a constant gradient ring, the lowest energy state is never ordered, but in an alternating gradient structure, operating below the transition energy, the lowest state is ordered. The nature and characteristics of the ground state depends upon the beam density and the ring parameters. For zero temperature the crystal remains intact for a very long time, but at nonzero temperatures it gains energy from the lattice. A critical temperature exists above which the crystal melts rapidly.

We describe a Nanostructure-Initiator Mass Spectrometry (NIMS) enzymatic (Nimzyme) assay in which enzyme substrates are immobilized on the mass spectrometry surface by using fluorous-phase interactions. This 'soft' immobilization allows efficient desorption/ionization while also enabling the use of surface-washing steps to reduce signal suppression from complex biological samples, which results from the preferential retention of the tagged products and reactants. The Nimzyme assay is sensitive to subpicogram levels of enzyme, detects both addition and cleavage reactions (sialyltransferase and galactosidase), is applicable over a wide range of pHs and temperatures, and can measure activity directly from crude cell lysates. The ability of the Nimzyme assay to analyze complex mixtures is illustrated by identifying and directly characterizing {beta}-1,4-galactosidase activity from a thermophilic microbial community lysate. The optimal enzyme temperature and pH were found to be 65 C and 5.5, respectively, and the activity was inhibited by both phenylethyl-{beta}-d-thiogalactopyranoside and deoxygalactonojirimycin. Metagenomic analysis of the community suggests that the activity is from an uncultured, unsequenced {gamma}-proteobacterium. In general, this assay provides an efficient method for detection and characterization of enzymatic activities in complex biological mixtures prior to sequencing or cloning efforts. More generally, this approach may have important applications for screening both enzymatic and …

High resolution mass spectrometers are specialized systems that allow researchers to determine the exact mass of samples to four significant digits by using magnetic and electronic sector mass analyzers. Many of the systems in use today at research laboratories and universities were designed and built more than two decades ago. The manufacturers of these systems have abandoned the support for some of the mass spectrometers and parts to power and control them have become scarce or obsolete. The Savannah River National Laboratory has been involved in the upgrade of the electronics and software for these legacy machines. The Electronics Upgrade of High Resolution Mass Spectrometers consists of assembling high-end commercial instrumentation from reputable manufacturers with a minimal amount of customization to replace the electronics for the older systems. By taking advantage of advances in instrumentation, precise magnet control can be achieved using high resolution current sources and continuous feedback from a high resolution hall-effect probe. The custom equipment include a precision voltage divider/summing amplifier chassis, high voltage power supply chassis and a chassis for controlling the voltage emission for the mass spectrometer source tube. The upgrade package is versatile enough to interface with valve control, vacuum and other instrumentation. Instrument …

Extended X-Ray Absorption Fine Structure (EXAFS), using a laser-imploded target as a source, can yield the properties of laser-shocked metals on a nanosecond time scale. EXAFS measurements of vanadium shocked to {approx}0.4 Mbar yield the compression and temperature in good agreement with hydrodynamic simulations and shock-speed measurements. In laser-shocked titanium at the same pressure, the EXAFS modulation damping is much higher than warranted by the predicted temperature increase. This is shown to be due to the {alpha}-Ti to {omega}-Ti crystal-phase transformation, known to occur below {approx}0.1 Mbar for slower shock waves. The dynamics of material response to shock loading has been extensively studied in the past [1]. The goal of those studies has been to understand the shock-induced deformation and structural changes at the microscopic level [2]. Laser-generated shocks can be employed to broaden these studies to higher pressures ({approx}1 Mbar) and strain rates ({approx} 10{sup 7}-10{sup 8} s{sup -1}). Recently, laser-shocked materials have been studied with in-situ x-ray diffraction [3,4]. The goal of this work is to examine the use of in-situ EXAFS [5] as a complementary characterization of laser-shocked metals. EXAFS is the modulation in the x-ray absorption above the K edge (or L edge) due to the …

The Microwave Tokamak Experiment (MTX) is under construction at LLNL to investigate the feasibility of intense, pulsed microwave radiation for plasma heating on future ignition tokamaks. A high-average-power free-electron laser (FEL) will use the Experimental Test Accelerator (ETA-II), a linear induction accelerator, in combination with an advanced high-field wiggler, to produce 1-2 MW of power at 1-2-mm wavelengths for periods of up to 0.5s. The design of the FEL, termed the intense microwave prototype (IMP), is described, along with the status and major issues associated with the status and major issues associated with the experiment. 10 refs., 8 figs., 4 tabs.

We discuss the DWY (Lagrangian), Quinn-Weinstein, and Rebbi proposals for incorporating fermions into lattice gauge theory and analyze them in the context of weak coupling perturbation theory. We find that none of these proposals leads to a completely satisfactory lattice transcription of fully-interacting gauge theory.

In our quest for accurate linear scaling first-principles molecular dynamics methods for pseudopotential DFT calculations, we investigate the accuracy of real-space grid approaches, with finite differences and spherical localization regions. We examine how the positions of the localization centers affect the accuracy and the convergence rate of the optimization process. In particular we investigate the accuracy of the atomic forces computation compared to the standard O(N{sup 3}) approach. We show the exponential decay of the error on the energy and forces with the size of the localization regions for a variety of realistic physical systems. We propose a new algorithm to automatically adapt the localization centers during the ground state computation which allows for molecular dynamics simulations with diffusion processes. The combination of algorithms proposed lead to a genuine linear scaling First-Principles Molecular Dynamics method with controlled accuracy. We illustrate our approach with examples of microcanonical molecular dynamics with localized orbitals.

Enhancing the proliferation resistance of nuclear energy systems and fuel cycles is an ambitious undertaking. Current systems, dominated by the light water reactor fuel cycle are quite proliferation resistant. However, continued accumulations of plutonium in spent fuel and accumulations of separated plutonium resulting from reprocessing are eroding the proliferation resistance of today's nuclear energy systems. Alternatives to address these issues invariably involve making trade-offs among different proliferation risks and advantages. For example, thorium cycles reduce the quantity and quality of plutonium in spent fuel, but do so at the expense of increased fresh fuel enrichment and/or production of separable U233. Evaluation of these tradeoffs is difficult, as there are serious and significant differences of opinion regarding the relative merits and significance of the various risks of and barriers to proliferation from commercial nuclear power fuel cycles.

The reflectance stability of multilayer coatings for extreme ultraviolet lithography (EUVL) in a commercial tool environment is of uttermost importance to ensure continuous exposures with minimum maintenance cost. We have made substantial progress in designing the protective capping layer coatings, understanding their performance and estimating their lifetimes based on accelerated electron beam and EUV exposure studies. Our current capping layer coatings have about 40 times longer lifetimes than Si-capped multilayer optics. Nevertheless, the lifetime of current Ru-capped multilayers is too short to satisfy commercial tool requirements and further improvements are essential.

This paper describes simulation and experimental results for a 1400A, {+-} 900V peak rated, switch mode power supply for SNS Injection Kicker Magnets. For each magnet (13 m{Omega}, 160{micro}H), the power supply must supply controlled pulses at 60 Hz repetition rate. The pulse current must rise from zero to maximum in less than 1 millisec in a controlled manner, flat top for up to 2 millisec, and should fall in a controlled manner to less than 4A within 500{micro}s. The low current performance during fall time is the biggest challenge in this power supply. The simulation results show that to meet the controlled fall of the current and the current ripple requirements, voltage loop bandwidth of at least 10 kHz and switching frequency of at least 100 kHz are required. To achieve high power high frequency switching with IGBT switches, a series connected topology with three phase shifted (O{sup o}, 60{sup o} & 120{sup o}) converters each with 40 kHz switching frequency (IGBT at 20kHz), has been achieved. In this paper, the circuit topology, relevant system specifications and experimental results that meet the requirements of the power supply are described in detail. A unique six pulse SCR rectifier circuit with …

The Spallation Neutron Source accelerator systems will provide a 1 GeV, 1.44 MW proton beam to a liquid mercury target for neutron production. Beam tuning dumps are provided at the end of the linac (the Linac Dump) and in the Ring-to-Target transport line (the Extraction Dump) [1]. Thin windows are required to separate the accelerator vacuum from the poor vacuum upstream of the beam dump. There are several challenging engineering issues that have been addressed in the window design. Namely, handling of the high local power density deposited by the stripped electrons from the H-beam accelerated in the linac, and the need for low-exposure removal and replacement of an activated window. The thermal design of the linac dump window is presented, as is the design of a vacuum clamp and mechanism that allows remote removal and replacement of the window.

The Spallation Neutron Source (SNS) accelerator systems will provide a 1 GeV, 1.44 MW proton beam to a liquid mercury target for neutron production. In order to satisfy the accelerator systems' portion of the Critical Decision 4 (CD-4) commissioning goal (which marks the completion of the construction phase of the project), a beam pulse with intensity greater than 1 x 10{sup 13} protons must be accumulated in the ring, extracted in a single turn and delivered to the target. A commissioning plan has been formulated for bringing into operation and establishing nominal operating conditions for the various ring and transport line subsystems as well as for establishing beam conditions and parameters which meet the commissioning goal.

Five actual Savannah River Site tank waste samples and three chemically-modified samples were tested to determine solubility limits for uranium and plutonium over a one year time period. Observed final uranium concentrations ranged from 7 mg U/L to 4.5 g U/L. Final plutonium concentrations ranged from 4 {micro}g Pu/L to 12 mg Pu/L. Actinide carbonate complexation is believed to result in the dramatic solubility increases observed for one sample over long time periods. Clarkeite, NaUO{sub 2}(O)OH {center_dot} H{sub 2}O, was found to be the dominant uranium solid phase in equilibrium with the waste supernate in most cases.

The longitudinal coherence of free-electron laser (FEL) radiation can be enhanced by seeding the FEL with high harmonics of an optical laser pulse. The radiation produced by high-harmonic generation (HHG), however, has a fast-varying temporal profile that can violate the slowly varying envelope approximation and limited frequency window that is employed in conventional free-electron laser simulation codes. Here we investigate the implications of violating this approximation on the accuracy of simulations. On the basis of both analytical considerations and 1D numerical studies, it is concluded that, for most realistic scenarios, conventional FEL codes are capable of accurately simulating the FEL process even when the seed radiation violates the slowly varying envelope approximation. We additionally discuss the significance of filtering the harmonic content of broadband HHG seeds.

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