Some of the planned core diagnostics for National Ignition Facility (NIF) will use neutron time-of-flight (TOF) spectroscopy techniques to gather information for primary neutron yield measurement or neutron imaging. This technique has been widely and routinely used at other laser facilities including Nova and Omega. TOF methods will also be used to observe target fuel areal density <{rho}R> (radial integral of density) via measuring the number of primary 14.1 MeV neutrons that are down-scattered to lower energies by nuclear collisions inside the compressed target core. The substantially larger target chamber size and higher neutron yield for NIF raises issues related to the large number of scattered neutrons produced by high yield deuterium-tritium (D-T) shots at NIF. The effect of primary neutrons scattered by the walls of the massive target chamber and structures both inside and outside the chamber will contribute a significant scattered background signal when trying to determine the number of neutrons down-scattered from the target core. The optimum detector locations outside the target chamber or target bay wall will be proposed. Appropriate collimators at the chamber port and the bay wall (between the neutron source at target chamber center (TCC) and detector) that maximize detection of signal neutrons …

UDP-glucuronosyltransferases (UGTs) catalyze the glucuronidation of many different chemicals. Glucuronidation is especially important for detoxifying reactive intermediates from metabolic reactions, which otherwise can be biotransformed into highly reactive cytotoxic or carcinogenic species. Detoxification of certain food-borne carcinogenic heterocyclic amines (HAs) is highly dependent on UGT1A-mediated glucuronidation. 2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), the most mass abundant carcinogenic HA found in well-done cooked meat, is extensively glucuronidated by UGT1A proteins. In humans, CYP1A2 catalyzed N-hydroxylation and subsequent UGT1A-mediated glucuronidation is a dominant pathway in the metabolism of PhIP. Therefore, changes in glucuronidation rates could significantly alter PhIP metabolism. To determine the importance of UGT1A-mediated glucuronidation in the biotransformation of PhIP, UGT1A proficient Wistar and UGT1A deficient Gunn rats were exposed to a single 100 {micro}g/kg oral dose of [{sup 14}C]-PhIP. Urine was collected over 24 h and the PhIP urinary metabolite profiles were compared between the two strains. After the 24 h exposure, livers and colon were removed and analyzed for DNA adduct formation by accelerator mass spectrometry. Wistar rats produced several PhIP and N-hydroxy-PhIP glucuronides that accounted for {approx}25% of the total amount of recovered urinary metabolites. In the Gunn rats, PhIP and N-hydroxy-PhIP glucuronides were reduced by 68-92%, compared to the Wistar rats, …

Although age is recognized as the strongest predictor of mortality in chronic disease epidemiology, a calendar-based approach is often employed when evaluating time-related variables. An age-based analysis file, created by determining the value of each time-dependent variable for each age that a cohort member is followed, provides a clear definition of age at exposure and allows development of diverse analytic models. To demonstrate methods, the relationship between cancer mortality and external radiation was analyzed with Poisson regression for 14,095 Oak Ridge National Laboratory workers. Based on previous analysis of this cohort, a model with ten-year lagged cumulative radiation doses partitioned by receipt before (dose-young) or after (dose-old) age 45 was examined. Dose-response estimates were similar to calendar-year-based results with elevated risk for dose-old, but not when film badge readings were weekly before 1957. Complementary results showed increasing risk with older hire ages and earlier birth cohorts, since workers hired after age 45 were born before 1915, and dose-young and dose-old were distributed differently by birth cohorts. Risks were generally higher for smokingrelated than non-smoking-related cancers. It was difficult to single out specific variables associated with elevated cancer mortality because of: (1) birth cohort differences in hire age and mortality experience …

Phase 1 of isotopes in the Project for Intercomparison of Land-surface Parameterization Schemes (iPILPS) compares the simulation of two stable water isotopologues ({sup 1}H{sub 2} {sup 18}O and {sup 1}H{sup 2}H{sup 16}O) at the land-atmosphere interface. The simulations are off-line, with forcing from an isotopically enabled regional model for three locations selected to offer contrasting climates and ecotypes: an evergreen tropical forest, a sclerophyll eucalypt forest and a mixed deciduous wood. Here we report on the experimental framework, the quality control undertaken on the simulation results and the method of intercomparisons employed. The small number of available isotopically-enabled land-surface schemes (ILSSs) limits the drawing of strong conclusions but, despite this, there is shown to be benefit in undertaking this type of isotopic intercomparison. Although validation of isotopic simulations at the land surface must await more, and much more complete, observational campaigns, we find that the empirically-based Craig-Gordon parameterization (of isotopic fractionation during evaporation) gives adequately realistic isotopic simulations when incorporated in a wide range of land-surface codes. By introducing two new tools for understanding isotopic variability from the land surface, the Isotope Transfer Function and the iPILPS plot, we show that different hydrological parameterizations cause very different isotopic responses. We …

This article discusses developments in environmental analytical chemistry that occurred in the years of 2003 and 2004. References were found by searching the ''Science Citation Index and Current Contents''. As in our review of two years ago (A1), techniques are highlighted that represent current trends and state-of-the-art technologies in the sampling, extraction, separation, and detection of trace concentrations, low-part-per-billion and less, of organic, inorganic, and organometallic contaminants in environmental samples. New analytes of interest are also reviewed, the detections of which are made possible by recently developed analytical instruments and methods.

We are developing an edge gyro-kinetic continuum simulation code to study the boundary plasma over a region extending from inside the H-mode pedestal across the separatrix to the divertor plates. A 4-D ({psi}, {theta}, {epsilon}, {mu}) version of this code is presently being implemented, en route to a full 5-D version. A set of gyrokinetic equations[1] are discretized on computational grid which incorporates X-point divertor geometry. The present implementation is a Method of Lines approach where the phase-space derivatives are discretized with finite differences and implicit backwards differencing formulas are used to advance the system in time. A fourth order upwinding algorithm is used for particle cross-field drifts, parallel streaming, and acceleration. Boundary conditions at conducting material surfaces are implemented on the plasma side of the sheath. The Poisson-like equation is solved using GMRES with multi-grid preconditioner from HYPRE. A nonlinear Fokker-Planck collision operator from STELLA[2] in ({nu}{sub {parallel}},{nu}{sub {perpendicular}}) has been streamlined and integrated into the gyro-kinetic package using the same implicit Newton-Krylov solver and interpolating F and dF/dt|{sub coll} to/from ({epsilon}, {mu}) space. With our 4D code we compute the ion thermal flux, ion parallel velocity, self-consistent electric field, and geo-acoustic oscillations, which we compare with standard neoclassical …

Sequencing of full-insert clones from full-length cDNA libraries from both Xenopus laevis and Xenopus tropicalis has been ongoing as part of the Xenopus Gene Collection initiative. Here we present an analysis of 10967 clones (8049 from X. laevis and 2918 from X. tropicalis). The clone set contains 2013 orthologs between X. laevis and X. tropicalis as well as 1795 paralog pairs within X. laevis. 1199 are in-paralogs, believed to have resulted from an allotetraploidization event approximately 30 million years ago, and the remaining 546 are likely out-paralogs that have resulted from more ancient gene duplications, prior to the divergence between the two species. We do not detect any evidence for positive selection by the Yang and Nielsen maximum likelihood method of approximating d{sub N}/d{sub S}. However, d{sub N}/d{sub S} for X. laevis in-paralogs is elevated relative to X. tropicalis orthologs. This difference is highly significant, and indicates an overall relaxation of selective pressures on duplicated gene pairs. Within both groups of paralogs, we found evidence of subfunctionalization, manifested as differential expression of paralogous genes among tissues, as measured by EST information from public resources. We have observed, as expected, a higher instance of subfunctionalization in out-paralogs relative to in-paralogs.

The Rare Earth elements (REE) are known to undergo crystallographic as well as electronic structure changes with applied pressure. On increasing pressure, the trivalent lanthanides follow the sequence hcp {yields} Sm-type {yields} dhcp {yields} fcc {yields} dfcc. In this report we present room-temperature high-pressure x-ray diffraction data for Dy as well as our observations on the post-dfcc phases and concomitant volume changes in the heavy REE.

We report the discovery of the new gravitational lens system CLASS B0631+519. Imaging with the VLA, MERLIN and the VLBA reveals a doubly-imaged flat-spectrum radio core, a doubly-imaged steep-spectrum radio lobe and possible quadruply-imaged emission from a second lobe. The maximum separation between the lensed images is 1.16 arcsec. High resolution mapping with the VLBA at 5 GHz resolves the most magnified image of the radio core into a number of sub-components spread across approximately 20 mas. No emission from the lensing galaxy or an odd image is detected down to 0.31 mJy (5{sigma}) at 8.4 GHz. Optical and near-infrared imaging with the ACS and NICMOS cameras on the HST show that there are two galaxies along the line of sight to the lensed source, as previously discovered by optical spectroscopy. We find that the foreground galaxy at z=0.0896 is a small irregular, and that the other, at z=0.6196 is a massive elliptical which appears to contribute the majority of the lensing effect. The host galaxy of the lensed source is detected in the HST near-infrared imaging as a set of arcs, which form a nearly complete Einstein ring. Mass modeling using non-parametric techniques can reproduce the near-infrared observations and …

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Among the many exceptional properties of Pu is its apparent lack of either local moments or cooperative magnetism. Lashley et al., have recently noted that little experimental evidence for the existence of local moments or collective magnetism has been found in over 50 years. Nevertheless the search for local moments in Pu and Pu-alloys continues, why? Plutonium's physical properties: resistance, magnetic susceptibility, and heat capacity, all support a system with an enhanced electron density of states. Pu sits on the edge of both magnetism and superconductivity and possesses one of the highest elemental Pauli susceptibilities, consistent with a highly correlated electron system. The low-density {delta}-Pu has eluded full first principles description and is both a challenge and an area of active investigation for theorists. The complex changes associated with the transition between the light and heavy actinides happen within the phase diagram of Pu, thus making Pu an intriguing and challenging solid-state system for continuing experimental and theoretical investigation. Recently, Griveau et al., observed the variations in the resistance and superconducting properties of Am metal as a function of pressure to 27GPa and T>0.4K. They postulate that the interesting features in the superconducting critical temperature, T{sub c}, vs. pressure, indicate …

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A one-day workshop sponsored by UC Irvine's Center for Urban Infrastructure, bringing together 20 state departments of transportation and environmental quality to discuss national coordination on alternative fuels.

My talk will focus on our recent computational modeling results of uranium corrosion and the impact of impurities on uranium corrosion, which occurs primarily through hydriding Uranium hydriding is one of the most important processes that has received considerable attention over many years. Although significant number of experimental and modeling studies have been carried out concerning thermo chemistry, diffusion kinetics and mechanisms of U-hydriding, very little is known about the electronic structure and electronic features that govern the U-hydriding process. Our modeling efforts focus the electronic feature that controls the activation barrier and thus the rate of hydriding. Our recent efforts have been focused on the role of impurities such as Fe, Cr, Si, C, Al and so on. Moreover the role of impurities and the role of the product UH{sub 3} on hydriding rating have not been fully understood. Condon's diffusion model was found to be in excellent agreement with the experimental reaction rates. From the slopes of the Arrhenius plot the activation energy was calculated as 6.35 kcal/mole. Bloch and Mintz have discussed two models, one, which considers hydrogen diffusion through a protective UH{sub 3} product layer, and the second where hydride growth occurs at the hydride-metal interface. …