This article operationalizes social network structure within the study of secularism, discusses the available research with a focus on atheism in particular, and integrates this research into a schematic theoretical model of atheist self-identity, network structure and health.

This article considers the count and types of traumas (polytraumatization) in relation to post-trauma mental health by conducting a study on the relation of polytraumatization patterns to PTSD clusters, depression, and impulsivity facets. Results indicate that individuals exposed to multiple PTE (potentially traumatizing event) types, particularly interpersonal traumas, may be at risk for more severe post-trauma symptoms.

Article describes study which indicates that nuclear type 2C protein phosphatase (PP2Cδ) impairs p53 acetylation and DNA damage response by compromising BRCA1 function in breast cancer development.

A novel method for determining the equation-of-state (EOS) along the release isentrope in an isochoric (constant volume) heated plasma is presented. The sensitivity of this approach is demonstrated using two different equation-of-state models for a solid density, 10 eV expanding Al plasma. Determining the material EOS data is validated to pressures near 80 Mbar, much higher than current isentropic compression experiments allow. Limitations at high temperature (T{sub e} {ge} 100 eV) due to the formation of a radiative conduction layer near the rarefaction interface are also illustrated.

One problem in similarity-based object retrieval (SBOR) is how to define and estimate the similarity between two objects. In this paper we present a shape similarity measure based on thin-plate splines, and compare its performance with several other measures used in SBOR. We evaluate the methods on both artificial and real images.

Transformation superplasticity is a deformation mechanism induced by thermally-cycling a polymorphic material through the phase transformation range while simultaneously applying an external biasing stress. Unlike microstructural superplasticity, which requires a fine, equiaxed grain structure, this mechanism can be applied to coarse-grained alloys and composites. In this article, we review our research on transformation superplasticity of Ti-6Al-4V/TiB-whisker reinforced composites, during thermal cycling through the titanium {alpha}/{beta} transformation range. The composites exhibit Newtonian flow and superplastic extension under these conditions. We describe the constitutive behavior of composites containing 0, 5 and 10 vol% reinforcing whiskers, and consider the effects of load transfer from matrix to whisker on superplastic deformation using existing rheological models. Additionally, strain hardening due to gradual whisker alignment is observed, and rationalized in terms of increased load transfer for aligned whiskers.

The National Ignition Facility (NIF) laser focuses 1.8 megajoules of ultraviolet light (wavelength 351 nanometers) from 192 beams into a 600-micrometer-diameter volume. Effective use of this output in target experiments requires that the power output from all of the beams match within 8% over their entire 20-nanosecond waveform. The scope of NIF beam diagnostics systems necessary to accomplish this task is unprecedented for laser facilities. Each beamline contains 110 major optical components distributed over a 510-meter path, and diagnostic tolerances for beam measurement are demanding. Total laser pulse energy is measured with 2.8% precision, and the interbeam temporal variation of pulse power is measured with 4% precision. These measurement goals are achieved through use of approximately 160 sensor packages that measure the energy at five locations and power at three locations along each beamline using 335 photodiodes, 215 calorimeters, and 36 digitizers. Successful operation of such a system requires a high level of automation of the widely distributed sensors. Computer control systems provide the basis for operating the shot diagnostics with repeatable accuracy, assisted by operators who oversee system activities and setup, respond to performance exceptions, and complete calibration and maintenance tasks.

Objects of various shapes, with some appreciable hydrogen content, were exposed to fast neutrons from a pulsed D-T generator, resulting in a partially-moderated spectrum of backscattered neutrons. The thermal component of the backscatter was used to form images of the objects by means of a coded aperture thermal neutron imaging system. Timing signals from the neutron generator were used to gate the detection system so as to record only events consistent with thermal neutrons traveling the distance between the target and the detector. It was shown that this time-of-flight method provided a significant improvement in image contrast compared to counting all events detected by the position-sensitive {sup 3}He proportional chamber used in the imager. The technique may have application in the detection and shape-determination of land mines, particularly non-metallic types.

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A variety of approaches for handling effluent from nuclear thermal propulsion system ground tests in an environmentally acceptable manner are discussed. The functional requirements of effluent treatment are defined and concept options are presented within the framework of these requirements. System concepts differ primarily in the choice of fission-product retention and waste handling concepts. The concept options considered range from closed cycle (venting the exhaust to a closed volume or recirculating the hydrogen in a closed loop) to open cycle (real time processing and venting of the effluent). This paper reviews the strengths and weaknesses of different methods to handle effluent from nuclear thermal propulsion system ground tests.

As a result of 828 underground nuclear weapons tests conducted between 1951 and 1992 at the Nevada Test Site (NTS), more than 1E+6 TBq of long-lived radionuclides (actinide device residuals, fission and activation products, etc.) are residual. Included in the radiologic inventory are {sup 99}Tc (technetium) and {sup 129}I (iodine) that are presumably mobile in groundwater and potentially toxic to down-gradient receptors. Understanding the controls of radionuclide mobility associated with these nuclear tests provides insights into the behavior of these same radionuclides in groundwater associated with the proposed Yucca Mountain high-level nuclear waste repository as well as the fidelity of numerical predictions of long-term repository performance. We synthesize a substantial body of data collected on the distribution of {sup 99}Tc and {sup 129}I associated with radionuclide migration studies at NTS, at field scales over distances of hundreds of meters and for durations up to forty years, under hydrogeologic conditions very similar to the proposed geological repository at Yucca Mountain. The results show that Tc does not necessarily exist as a mobile and conservative species TcO{sub 4}{sup -}, as commonly assumed. This is not unexpected as the speciation and migration behavior of {sup 99}Tc will be significantly controlled by the redox …

We present a second-order Godunov algorithm for multidimensional, ideal MHD. Our algorithm is based on the unsplit formulation of Colella, with all of the primary dependent variables centered at the same location. To properly represent the divergence-free condition of the magnetic fields, we apply a discrete projection to the intermediate values of the field at cell faces, and apply a filter to the primary dependent variables at the end of each time step. We apply the method to a suite of linear and nonlinear tests to ascertain accuracy and stability of the scheme under a variety of conditions. The test suite includes rotated planar linear waves, MHD shock tube problems, and low-beta flux tubes. For all of these cases, we observe that the algorithm is second-order accurate for smooth solutions, converges to the correct weak solution for problems involving shocks, and exhibits no evidence of instability or loss of accuracy due to the possible presence of non-solenoidal fields.

Successful dynamic Z-pinch experiments generally require good current delivery to the target load. Power flow losses through highly inductive transmission line configurations reduce the current available to the load. In this Brief Report, a variational calculus technique is used to determine the transmission line configuration that produces the least possible inductance and therefore the best possible current delivery for Z-pinch experiments.

We report on the performance of an S-band RF photocathode electron gun and accelerator for operation with the PLEIADES Thomson x-ray source at LLNL. To produce picosecond, high brightness x-ray pulses, picosecond timing, terahertz bandwidth diagnostics, and RF phase control are required. Planned optical, RF, x-ray and electron beam measurements to characterize the dependence of electron beam parameters and synchronization on RF phase stability are presented.

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The Peak Detector/Derandomizer ASIC (PDD) provides threshold discrimination, peak detection, time-to-amplitude conversion, analog memory, sparsification, and multiplexing for 32 channels of analog pulse data. In this work the spectroscopic capabilities of the chip (high resolution and high rate) are demonstrated along with correlated measurements of pulse risetime. Imaging and coincidence detection using the PDD chip will also be illustrated.

Multiresolution texture-based volume visualization is an excellent technique to enable interactive rendering of massive data sets. Interactive manipulation of a transfer function is necessary for proper exploration of a data set. However, multiresolution techniques require assessing the accuracy of the resulting images, and re-computing the error after each change in a transfer function is very expensive. They extend their existing multiresolution volume visualization method by introducing a method for accelerating error calculations for multiresolution volume approximations. Computing the error for an approximation requires adding individual error terms. One error value must be computed once for each original voxel and its corresponding approximating voxel. For byte data, i.e., data sets where integer function values between 0 and 255 are given, they observe that the set of error pairs can be quite large, yet the set of unique error pairs is small. instead of evaluating the error function for each original voxel, they construct a table of the unique combinations and the number of their occurrences. To evaluate the error, they add the products of the error function for each unique error pair and the frequency of each error pair. This approach dramatically reduces the amount of computation time involved and allows …

Star formation within dwarf galaxies is governed by several factors. Many of these factors are external, including ram-pressure stripping, tidal stripping, and heating by external UV radiation. The latter, in particular, may prevent star formation in the smallest systems. Internal factors include negative feedback in the form of UV radiation, winds and supernovae from massive stars. These act to reduce the star formation efficiency within dwarf systems, which may, in turn, solve several theoretical and observational problems associated with galaxy formation. In this contribution, we discuss our recent work being done to examine the importance of the many factors in the evolution of dwarf galaxies.

The Integrated Computer Control System (ICCS) is based on a scalable software framework that is distributed over some 325 computers throughout the NIF facility. The framework provides templates and services at multiple levels of abstraction for the construction of software applications that communicate via CORBA (Common Object Request Broker Architecture). Various forms of object-oriented software design patterns are implemented as templates to be extended by application software. Developers extend the framework base classes to model the numerous physical control points, thereby sharing the functionality defined by the base classes. About 56,000 software objects each individually addressed through CORBA are to be created in the complete ICCS. Most objects have a persistent state that is initialized at system start-up and stored in a database. Additional framework services are provided by centralized server programs that implement events, alerts, reservations, message logging, database/file persistence, name services, and process management. The ICCS software framework approach allows for efficient construction of a software system that supports a large number of distributed control points representing a complex control application.

Clay-poor lahars of late Holocene age from Mount Rainier change down the White River drainage into lahar-derived fluvial and deltaic deposits that filled an arm of Puget Sound between the sites of Auburn and Seattle, 110-150 km downvalley from the volcano's summit. Lahars in the debris-flow phase left cobbly and bouldery deposits on the walls of valleys within 70 km of the summit. At distances of 80-110 km, transitional (hyperconcentrated) flows deposited pebbles and sand that coat terraces in a gorge incised into glacial drift and the mid-Holocene Osceola Mudflow. On the broad, level floor of the Kent valley at 110-130 km, lahars in the runout or streamflow phase deposited mostly sand-size particles that locally include the trunks of trees probably entrained by the flows. Beyond 130 km, in the Duwamish valley of Tukwila and Seattle, laminated andesitic sand derived from Mount Rainier built a delta northward across the Seattle fault. This distal facies, warped during an earthquake in A.D. 900-930, rests on estuarine mud at depths as great as 20 m. The deltaic filling occurred in episodes that appear to overlap in time with the lahars. As judged from radiocarbon ages of twigs and logs, at least three episodes …

The National Ignition Facility (NIF), currently under construction at the University of California's Lawrence Livermore National Laboratory, is a stadium-sized facility containing a 192-beam, 1.8-Megajoule, 500-Terawatt, 351-nm laser system and a 10-meter diameter target chamber with room for nearly 100 experimental diagnostics. NIF is being built by the National Nuclear Security Administration and when completed will be the world's largest laser experimental system, providing a national center to study inertial confinement fusion and the physics of matter at extreme energy densities and pressures. NIF will provide 192 energetic laser beams that will compress small fusion targets to conditions where they will ignite and burn, liberating more energy than is required to initiate the fusion reactions. NIF experiments will allow the study of physical processes at temperatures approaching 100 million K and 100 billion times atmospheric pressure. These conditions exist naturally only in the interior of stars and in nuclear weapons explosions. In the course of designing the world's most energetic laser system, a number of significant technology breakthroughs have been achieved. Research is also underway to develop a shorter pulse capability on NIF for very high power and extreme electromagnetic field research and applications. We discuss here the technology challenges …

Fast ignition (FI) has significant potential advantages for inertial fusion energy and it is therefore being studied as an exploratory concept in the US fusion energy program. FI is based on short pulse isochoric heating of pre-compressed DT by intense beams of laser accelerated MeV electrons or protons. Recent experimental progress in the study of these two heating processes is discussed. The goal is to benchmark new models in order to predict accurately the requirements for full-scale fast ignition. An overview is presented of the design and experimental testing of a cone target implosion concept for fast ignition. Future prospects and conceptual designs for larger scale FI experiments using planned high energy petawatt upgrades of major lasers in the US are outlined. A long-term roadmap for FI is defined.

The Fokker-Planck package FPPAC had been converted to the Connection Machine 2 (CM2). For fine mesh cases the CM2 outperforms the Cray-2 when it comes to time-integrating the difference equations. For long Legendre expansions the CM2 is also faster at computing the Fokker-Planck coefficients. 3 refs.

We have derived absolute dipole strength-function information for /sup 176/Lu from an average resonance capture study of /sup 175/Lu with 2-keV neutrons and from neutron capture cross-section measurements with neutrons from 30 keV to about 1 MeV. We found that we needed to increase our previous estimate of the relative M1/E1 strengths near 5 MeV by a factor of 3 and to revise downward the absolute magnitude of our E1 strength function. We accomplished the latter, while still maintaining continuity with the photonuclear data, by adjusting the one free parameter in our line shape. The present E1 and M1 strengths now seem correct both near the neutron separation energy and also around 1 MeV.