Magnetic Resonance Imaging (MRI) techniques have been used to detect areas of low crosslink density in damaged silicone parts in an effort to develop a QA/QC protocol to be used in the development of new parts. Model materials of varying crosslink density first demonstrated the applicability of the method. Analysis of damaged pads has been shown to be clearly distinguishable by MRI. It is our belief that both the T{sub 2} weighted SPI NMR and the T{sub 2} weighted water/fat suppression MRI experiments can be used to map out the location of different cross-linking densities, ultimately determining the quality or homogeneity in polymers.

We discuss the motivation, theory, and formulation of the ab initio No-Core Shell Model (NCSM). In this method the effective Hamiltonians are derived microscopically from realistic nucleon-nucleon (NN) and theoretical three-nucleon (NNN) potentials, as a function of the finite harmonic-oscillator (HO) basis space. We present converged results for the A = 3 and 4 nucleon systems, which are in agreement with results obtained by other exact methods, followed by results for p-shell nuclei. Binding energies, rms radii, excitation spectra, and electromagnetic properties are discussed.The favorable comparison with available data is a consequence of the underlying NN and NNN interactions rather than a phenomenological fit.

The study of materials properties under extreme conditions has made considerable progress over the past decade due to both improvements in experimental techniques and advanced modeling methods. The availability of accurate models is crucial in order to analyze experimental results obtained in extreme conditions of pressure and temperature where experimental data can be scarce. Among theoretical models, ab initio simulations are playing an increasingly important role due to their ability to predict materials properties without the need for any experimental input. Ab initio simulations also allow for an exploration of materials properties in conditions that are unachievable using controlled experiments--such as e.g. the conditions prevailing in the core of large planets. In that limit, they constitute the only quantitative model of condensed matter available today. In this article, we review the current status of ab initio simulations and discuss examples of recent applications in which numerical simulations have provided an essential complement to experimental data.

Preferential flow commonly observed in unsaturated soils allows rapid movement of solute from the soil surface or vadose zone to the groundwater, bypassing a significant volume of unsaturated soil and increasing the risk of groundwater contamination. A variety of evidence indicates that complex preferential patterns observed from fields are fractals. In this study, we developed a relatively simple active region model to incorporate the fractal flow pattern into the continuum approach. In the model, the flow domain is divided into active and inactive regions. Flow occurs preferentially in the active region (characterized by fractals), and inactive region is simply bypassed. A new constitutive relationship (the portion of the active region as a function of saturation) was derived. The validity of the proposed model is demonstrated by the consistency between field observations and the new constitutive relationship.

This report describes the development of a simple active region model to incorporate the fractal flow pattern into the continuum approach.

Measurements of organic carbon (OC) and black carbon (BC)concentrations over a variety of locations worldwide, have been analyzed to infer the spatial distributions of the ratios of OC to BC. Since these ratios determine the relative amounts of scattering and absorption, they are often used to estimate the radiative forcing due to aerosols. An artifact in the protocol for filter measurements of OC has led to widespread overestimates of the ratio of OC to BC in atmospheric aerosols. We developed a criterion to correct for this artifact and analyze corrected OC to BC ratios. The OC to BC ratios, ranging from 1.3to 2.4, appear relatively constant and are generally unaffected by seasonality, sources or technology changes, at the locations considered here. The ratios compare well with emission inventories over Europe and China but are a factor of two lower in other regions. The reduced estimate for OC/BC in aerosols strengthens the argument that reduction of soot emissions maybe a useful approach to slow global warming.

Regional seismic discriminants based on high-frequency P/S ratios reliably distinguish between earthquakes and explosions. However, P/S discriminants in the 0.5 to 3 Hz band (where SNR can be highest) rarely perform well, with similar ratios for earthquake and explosion populations. Variability in discriminant performance has spawned numerous investigations into the generation of S-waves from explosions. Several viable mechanisms for the generation of S-waves from explosions have been forwarded, but most of these mechanisms do not explain observations of frequency-dependant S-wave generation. Recent studies have focused on the affect of near-source scattering to explain the frequency-dependence of both S-wave generation and P/S discriminant performance. In this study we investigate near-source scatter through numerical simulation with a realistic geological model We have constructed a realistic, 3-dimensional earth model of the southern Basin and Range. This regional model includes detailed constraints at the Nevada Test Site (NTS) based on extensive geologic and geophysical studies. Gross structure of the crust and upper mantle is taken from regional surface-wave studies. Variations in crustal thickness are based on receiver function analysis and a compilation of reflection/refraction studies. Upper-crustal constraints are derived from geologic maps and detailed studies of sedimentary basin geometry throughout the study area. The …

Article about shops, music performances, and events around Austin, Texas in November of 2005.

The month-to-month variability of tropical temperatures is larger in the troposphere than at the Earth's surface. This amplification behavior is similar in a range of observations and climate model simulations, and is consistent with basic theory. On multi-decadal timescales, tropospheric amplification of surface warming is a robust feature of model simulations, but occurs in only one observational dataset. Other observations show weak or even negative amplification. These results suggest that either different physical mechanisms control amplification processes on monthly and decadal timescales, and models fail to capture such behavior, or (more plausibly) that residual errors in several observational datasets used here affect their representation of long-term trends.

The authors present a Dalitz-plot analysis of charmless B{sup {+-}} decays to the final state {pi}{sup {+-}}{pi}{sup {+-}}{pi}{sup {-+}} using 210 fb{sup -1} of data recorded by the BABAR experiment at {radical}s = 10.58 GeV. We measure the branching fractions {Beta}(B{sup {+-}} {yields} {pi}{sup {+-}}{pi}{sup {+-}}{pi}{sup {-+}}) = (16.2 {+-} 1.2 {+-} 0.9) x 10{sup -6} and {Beta}(B{sup {+-}} {yields} {rho}{sup 0}(770){pi}{sup {+-}}) = (8.8 {+-} 1.0 {+-} 0.6{sub -0.7}{sup +0.1}) x 10{sup -6}. Measurements of branching fractions for the quasi-two-body decays B{sup {+-}} {yields} {rho}{sup 0}(1450){pi}{sup {+-}}, B{sup {+-}} {yields} f{sub 0}(980){pi}{sup {+-}} and B{sup {+-}} f{sub 2}(1270){pi}{sup {+-}} are also presented. They observe no charge asymmetries for the above modes, and there is no evidence for the decays B{sup {+-}} {yields} {chi}{sub c0}{pi}{sup {+-}}, B{sup {+-}} {yields} f{sub 0}(1370){pi}{sup {+-}} and B{sup {+-}} {yields} {sigma}{pi}{sup {+-}}.

None

Radiation driven heat waves (Marshak Waves) are ubiquitous in astrophysics and terrestrial laser driven high energy density plasma physics (HEDP) experiments. Generally, the equations describing Marshak waves are so nonlinear, that solutions involving more than one spatial dimension require simulation. However, in this paper we show how one may analytically solve the problem of the two-dimensional nonlinear evolution of a Marshak wave, bounded by lossy walls, using an asymptotic expansion in a parameter related to the wall albedo and a simplification of the heat front equation of motion. Three parameters determine the nonlinear evolution, a modified Markshak diffusion constant, a smallness parameter related to the wall albedo, and the spacing of the walls. The final nonlinear solution shows that the Marshak wave will be both slowed and bent by the non-ideal boundary. In the limit of a perfect boundary, the solution recovers the original diffusion-like solution of Marshak. The analytic solution will be compared to a limited set of simulation results and experimental data.

We calculate the leading order BFKL amplitude for the exclusive diffractive process {gamma}*{sub L}(Q{sub 1}{sup 2}) {gamma}*{sub L}(Q{sub 2}{sup 2}) {yields} {rho}{sub L}{sup 0}{rho}{sub L}{sup 0} in the forward direction, which can be studied in future high energy e{sup +}e{sup -} linear colliders. The resummation effects are very large compared to the fixed-order calculation. We also estimate the next-to-leading logarithmic corrections to the amplitude by using a specific resummation of higher order effects and find a substantial growth with energy, but smaller than in the leading logarithmic approximation.

The authors present results of a study of 12 dust-reddened quasars with 0.4 < z < 2.65 and reddenings in the range 0.15 < E(B-V) < 1.7. They obtained ACIS-S X-ray spectra of these quasars, estimated the column densities towards them, and hence obtained the gas:dust ratios in the material obscuring the quasar. They detect all but one of the red quasars in the X-rays. Even though there is no obvious correlation between the X-ray determined column densities of the sources and their optical color or reddening, all of the sources show absorbed X-ray spectra. When they correct the luminosity for absorption, they can be placed among luminous quasars; therefore their objects belong to the group of high luminosity analogues of the sources contributing to the X-ray background seen in deep X-ray observations. Such sources are also found in serendipitous shallow X-ray surveys. There is a hint that the mean spectral slope of the red quasar is higher than that of normal, unobscured quasars, which could be an indication for higher accretion rates and/or an evolutionary effect. They investigate the number density of these sources compared to type 2 AGN based on the X-ray background and estimate how many moderate …

A considerable fraction of radioactivity entering the environment from different nuclear events is associated with particles. The impact of these events can only be fully assessed where there is some knowledge about the mobility of particle bound radionuclides entering the environment. The behavior of particulate radionuclides is dependent on several factors, including the physical, chemical and redox state of the environment, the characteristics of the particles (e.g., the chemical composition, crystallinity and particle size) and on the oxidative state of radionuclides contained in the particles. Six plutonium-containing particles stemming from Runit Island soil (Marshall Islands) were characterized using non-destructive analytical and microanalytical methods. By determining the activity of {sup 239,240}Pu and {sup 241}Am isotopes from their gamma peaks structural information related to Pu matrix was obtained, and the source term was revealed. Composition and elemental distribution in the particles were studied with synchrotron radiation based micro X-ray fluorescence (SR-{mu}-XRF) spectrometry. Scanning electron microscope equipped with energy dispersive X-ray detector (SEMEDX) and secondary ion mass spectrometer (SIMS) were used to examine particle surfaces. Based on the elemental composition the particles were divided into two groups; particles with plain Pu matrix, and particles where the plutonium is included in Si/O-rich matrix being …

We present the characterization of a positron emission tomograph for prostate imaging that centers a patient between a pair of external curved detector banks (ellipse: 45 cm minor, 70 cm major axis). The distance between detector banks adjusts to allow patient access and to position the detectors as closely as possible for maximum sensitivity with patients of various sizes. Each bank is composed of two axial rows of 20 HR+ block detectors for a total of 80 detectors in the camera. The individual detectors are angled in the transaxial plane to point towards the prostate to reduce resolution degradation in that region. The detectors are read out by modified HRRT data acquisition electronics. Compared to a standard whole-body PET camera, our dedicated-prostate camera has the same sensitivity and resolution, less background (less randoms and lower scatter fraction) and a lower cost. We have completed construction of the camera. Characterization data and reconstructed images of several phantoms are shown. Sensitivity of a point source in the center is 946 cps/mu Ci. Spatial resolution is 4 mm FWHM in the central region.

The newly reported Y(4260) becomes the second most massive state in the charmonium family. We argue that it displaces the {psi}(4415) as the (largely) 4s vector charmonium state, recall s-d wave interference to explain the lack of a signal in e{sup -}e{sup +} {yields} hadrons and suggest some further study avenues that can exclude exotic meson assignments. The absence of a J/{psi} KK mode can be understood, beyond phase space suppression, to be a consequence of chiral symmetry. We also provide a model calculation in this sector showing that, although forcing the fit somewhat (which suggests a small sea quark wavefunction component), the state can be incorporated in a standard scheme.

Dimensional changes related to temperature cycling of the {beta} and {delta} polymorphs of HMX (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine) are important for a variety of applications. The coefficient of thermal expansion (CTE) of the {beta} and {delta} phases are measured over a temperature range of -20 C to 215 C by thermo-mechanical analysis (TMA). Dimensional changes associated with the phase transition were also measured, and the time-temperature dependence of the dimensional change is consistent with phase transition kinetics measured earlier by differential scanning calorimetry (DSC). One HMX sample measured by TMA during its initial heating and again three days later during a second heating showed the {beta}-to-{delta} phase transition a second time, thereby indicating back conversion from {delta}-to-{beta} phase HMX during those three days. DSC was used to measure kinetics of the {delta}-to-{beta} back conversion. The most successful approach was to first heat the material to create the {delta} phase, then after a given period at room temperature, measure the heat absorbed during a second pass through the {beta}-to-{delta} phase transition. Back conversion at room temperature follows nucleation-growth kinetics.

The Collaboratory for Multi-scale Chemical Science (CMCS) is developing a powerful informatics-based approach to synthesizing multi-scale information to support a systems-based research approach and is applying it in support of combustion research. An open source multi-scale informatics toolkit is being developed that addresses a number of issues core to the emerging concept of knowledge grids including provenance tracking and lightweight federation of data and application resources into cross-scale information flows. The CMCS portal is currently in use by a number of high-profile pilot groups and is playing a significant role in enabling their efforts to improve and extend community maintained chemical reference information.

To provide a compact high-brightness heavy-ion beam source for Heavy Ion Fusion (HIF) accelerators, we have been experimenting with merging multi-beamlets in an injector which uses an RF plasma source. In an 80-kV 20-microsecond experiment, the RF plasma source has produced up to 5 mA of Ar{sup +} in a single beamlet. An extraction current density of 100 mA/cm{sup 2} was achieved, and the thermal temperature of the ions was below 1 eV. We have tested at full voltage gradient the first 4 gaps of an injector design. Einzel lens were used to focus the beamlets while reducing the beamlet to beamlet space charge interaction. We were able to reach greater than 100 kV/cm in the first four gaps. We also performed experiments on a converging 119 multi-beamlet source. Although the source has the same optics as a full 1.6 MV injector system, these test were carried out at 400 kV due to the test stand HV limit. We have measured the beam's emittance after the beamlets are merged and passed through an electrostatic quadrupole (ESQ). Our goal is to confirm the emittance growth and to demonstrate the technical feasibility of building a driver-scale HIF injector.

The Plasma and Ion Source Technology Group at Lawrence Berkeley National Laboratory has developed various types of advanced D-D (neutron energy 2.5 MeV), D-T (14 MeV) and T-T (0-9 MeV) neutron generators for wide range of applications. These applications include medical (Boron Neutron Capture Therapy), homeland security (Prompt Gamma Activation Analysis, Fast Neutron Activation Analysis and Pulsed Fast Neutron Transmission Spectroscopy) and planetary exploration with a sub-surface material characterization on Mars. These neutron generators utilize RF induction discharge to ionize the deuterium/tritium gas. This discharge method provides high plasma density for high output current, high atomic species from molecular gases, long life operation and versatility for various discharge chamber geometries. Four main neutron generator developments are discussed here: high neutron output co-axial neutron generator for BNCT applications, point neutron generator for security applications, compact and sub-compact axial neutron generator for elemental analysis applications. Current status of the neutron generator development with experimental data will be presented.

The one-dimensional harmonic oscillator in a box problem is possibly the simplest example of a two-mode system. This system has two exactly solvable limits, the harmonic oscillator and a particle in a (one-dimensional) box. Each of the two limits has a characteristic spectral structure describing the two different excitation modes of the system. Near each of these limits, one can use perturbation theory to achieve an accurate description of the eigenstates. Away from the exact limits, however, one has to carry out a matrix diagonalization because the basis-state mixing that occurs is typically too large to be reproduced in any other way. An alternative to casting the problem in terms of one or the other basis set consists of using an ''oblique'' basis that uses both sets. Through a study of this alternative in this one-dimensional problem, we are able to illustrate practical solutions and infer the applicability of the concept for more complex systems, such as in the study of complex nuclei where oblique-basis calculations have been successful.

None

Chemically amplified resists depend upon the post-exposure bake (PEB) process to drive the deprotection reactions (in positive resists) that lead to proper resist development. For this reason they often exhibit critical dimension (CD) sensitivity to PEB temperature variation. In this work the effects of variation in different aspects of the PEB step on post-develop CD are studied for two extreme ultraviolet (EUV) photoresists. The spatial and temporal temperature uniformity of the PEB plate is measured using a wireless sensor wafer. Programmed variations in the bake plate temperature set point are then used to measure the CD sensitivity to steady state temperature variation. In addition, the initial temperature ramp time is modified using a thin sheet of polyimide film between the wafer and the bake plate. This allows for measurement of the CD sensitivity to transient temperature variation. Finally, the bake time is adjusted to measure the CD sensitivity to this parameter.