Article showing that knockdown Arabidopsis plants with suppressed expression of the key water-water cycle enzyme, thylakoid-attached copper/zinc superoxide dismutase (KD-SOD), are suppressed in their growth and development. This article provides e genetic evidence for the importance of the water-water cycle in protecting the photosynthetic apparatus of higher plants from photooxidative damage.

Aquifer microcosms were used to determine how ethanol and methyl-tert-butyl ether (MtBE) affect monoaromatic hydrocarbon degradation under different electron-accepting conditions commonly found in contaminated sites experiencing natural attenuation. Response variability was investigated by using aquifer material from four sites with different exposure history. The lag phase prior to BTEX (benzene, toluene, ethylbenzene, and xylenes) and ethanol degradation was typically shorter in microcosms with previously contaminated aquifer material, although previous exposure did not always result in high degradation activity. Toluene was degraded in all aquifer materials and generally under a broader range of electron-accepting conditions compared to benzene, which was degraded only under aerobic conditions. MtBE was not degraded within 100 days under any condition, and it did not affect BTEX or ethanol degradation patterns. Ethanol was often degraded before BTEX compounds, and had a variable effect on BTEX degradation as a function of electron-accepting conditions and aquifer material source. An occasional enhancement of toluene degradation by ethanol occurred in denitrifying microcosms with unlimited nitrate; this may be attributable to the fortuitous growth of toluene-degrading bacteria during ethanol degradation. Nevertheless, experiments with flow-through aquifer columns showed that this beneficial effect could be eclipsed by an ethanol-driven depletion of electron acceptors, which …

A source evaluation case study is presented for observations of algae toxicity in an intermittent stream passing through the Lawrence Livermore National Laboratory near Livermore, California. A five-step procedure is discussed to determine the cause of water toxicity problems and to determine appropriate environmental management practices. Using this approach, an upstream electrical transfer station was identified as the probable source of herbicides causing the toxicity. In addition, an analytical solution for solute transport in overland flow was used to estimate the application level of 40 Kg/ha. Finally, this source investigation demonstrates that pesticides can impact stream water quality regardless of application within levels suggested on manufacturer labels. Environmental managers need to ensure that pesticides that could harm aquatic organisms (including algae) not be used within close proximity to streams or storm drainages and that application timing should be considered for environmental protection.

Facilities to support development of modified nitride-based reactor fuel pellets have been activated and are now in operation at Lawrence Livermore National Laboratory. These facilities provide the controls and monitored laboratory conditions required to produce, evaluate, and verify quality of the nitride-based product required for this fuel application. By preserving the high melting point, high thermal conductivity, and high actinide density properties of nitride fuel while enhancing stoichiometry, density, and grain structure, and by applying inert matrix (ZrN) and neutron absorbing (HfN) additives for improved stability and burn-up characteristics, the requirements for a long-life fuel to support sealed core reactor applications may be met. This paper discusses requirements for producing the modified nitride powders for sintering of fuel pellets, translation of these requirements into facility specifications, and implementation of these specifications as facility capabilities.

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.

We report the first neutron data for a single crystal Chemical Vapor Deposition (CVD) diamond sensor. Results are presented for 2.5, 14.1, and 14.9 MeV incident neutrons. We show that the energy resolution for 14.1 MeV neutrons is at least 2.9% (as limited by the energy spread of the incident neutrons), and perhaps as good as 0.4% (as extrapolated from high resolution {alpha} particle data). This result could be relevant to fusion neutron spectroscopy at machines like the International Thermonuclear Experimental Reactor (ITER). We also show that our sensor has a high neutron linear attenuation coefficient, due to the high atomic density of diamond, and this could lead to applications in fission neutron detection.

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.

We present a higher order kinetic Monte Carlo methodology suitable to model the evolution of systems in which the transition rates are non- trivial to calculate or in which Monte Carlo moves are likely to be non- productive flicker events. The second order residence time algorithm first introduced by Athenes et al.[1] is rederived from the n-fold way algorithm of Bortz et al.[2] as a fully stochastic algorithm. The second order algorithm can be dynamically called when necessary to eliminate unproductive flickering between a metastable state and its neighbors. An algorithm combining elements of the first order and second order methods is shown to be more efficient, in terms of the number of rate calculations, than the first order or second order methods alone while remaining statistically identical. This efficiency is of prime importance when dealing with computationally expensive rate functions such as those arising from long- range Hamiltonians. Our algorithm has been developed for use when considering simulations of vacancy diffusion under the influence of elastic stress fields. We demonstrate the improved efficiency of the method over that of the n-fold way in simulations of vacancy diffusion in alloys. Our algorithm is seen to be an order of magnitude …

Laboratory and field demonstration results obtained as part of the DARPA-sponsored Coherent Communications, Imaging and Targeting (CCIT) program are reviewed. The CCIT concept uses a Phase Conjugation Engine based on a quadrature receiver array, a hologram processor and a spatial light modulator (SLM) for high-speed, digital beam control. Progress on the enabling MEMS SLM, being developed by a consortium consisting of LLNL, academic institutions and small businesses, is presented.

Completion of cased and cemented wells by shaped-charge perforation results in damage to the formation, which can significantly reduce well productivity. Typically, underbalanced conditions are imposed during perforation in an effort to remove damaged rock and shaped-charge debris from the perforation tunnel. Immediately after the shaped-charge jet penetrates the formation, there is a transient surge of fluid from the formation through the perforation and into the well bore. Experimental evidence suggests that it is this transient pressure surge that leads to the removal of damaged rock and charge debris leaving an open perforation tunnel. We have developed a two-stage computational model to simulate the perforation process and subsequent pressure surge and debris removal. The first stage of the model couples a hydrocode with a model of stress-induced permeability evolution to calculate damage to the formation and the resulting permeability field. The second stage simulates the non-Darcy, transient fluid flow from the formation and removes damaged rock and charge debris from the perforation tunnel. We compare the model to a series of API RP43 section 4 flow tests and explore the influence of fluid viscosity and rock strength on the final perforation geometry and permeability.

A top-level overview of the mechanical design for the 2002 Robust Point Design (RPD-2002) fusion chamber is introduced. It is based on the HYLIFE-II design and includes modifications to the liquid pocket configuration and first structural wall (FSW), facilitates periodic maintenance or replacement of internal components, and is compliant with all other RPD-2002 parameters. This work has been carried out by constructing a parametric computer model capable of being updated as future changes become necessary.

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The process of interest in this study is the solidification of a molten metal subjected to rapid pressurization. Most details about solidification occurring when the liquid-solid coexistence line is suddenly transversed along the pressure axis remain unknown. We present preliminary results from an ongoing study of this process for both simple models of metals (Cu) and more sophisticated material models (MGPT potentials for Ta). Atomistic (molecular dynamics) simulations are used to extract details such as the time and length scales that govern these processes. Starting with relatively simple potential models, we demonstrate how molecular dynamics can be used to study solidification. Local and global order parameters that aid in characterizing the phase have been identified, and the dependence of the solidification time on the phase space distance between the final (P,T) state and the coexistence line has been characterized.

Contact modeling is still one of the most difficult aspects of nonlinear implicit structural analysis. Most 3D contact algorithms employed today use node-on-segment approaches for contacting dissimilar meshes. Two pass node-on-segment contact approaches have the well known deficiency of locking due to over constraint. Furthermore, node-on-segment approaches suffer when individual nodes slide out of contact at contact surface boundaries or when contacting nodes slide from facet to facet. This causes jumps in the contact forces due to the discrete nature of the constraint enforcement and difficulties in convergence for implicit solution techniques. In a previous work, we developed a segment-to-segment contact approach based on the mortar method that was applicable to large deformation mechanics. The approach proved extremely robust since it eliminated the overconstraint which caused ''locking'' and provided smooth force variations in large sliding. Here, we extend this previous approach in to treat frictional contact problems. The proposed approach is then applied to several challenging frictional contact problems which demonstrate its effectiveness.

The PLEIADES (Picosecond Laser-Electron Inter-Action for the Dynamical Evaluation of Structures) facility has produced first light at 70 keV. This milestone offers a new opportunity to develop laser-driven, compact, tunable x-ray sources for critical applications such as diagnostics for the National Ignition Facility and time-resolved material studies. The electron beam was focused to 50 {micro}m rms, at 57 MeV, with 260 C of charge, a relative energy spread of 0.2%, and a normalized emittance of 5 mm mrad horizontally and 13 mm mrad vertically. The scattered 820-nm laser pulse had an energy of 180 mJ and a duration of 54 fs. Initial x-rays were captured with a cooled charge-coupled device using a Cesium Iodide scintillator; the peak photon energy was approximately 78 keV, with a total x-ray flux of 1.3 x 10{sup 6} photons/shot, and the observed angular distribution found to agree very well with three-dimensional codes. Simple K-edge radiography of a tantalum foil showed good agreement with the theoretical divergence-angle dependence of the x-ray energy. Optimization of the x-ray dose is currently underway, with the goal of reaching 10{sup 8} photons per shot and a peak brightness approaching 10{sup 20} photons/mm{sup 2}/mrad{sup 2}/s/0.1%bandwidth.

Synchrotron Radiation (SR) has been widely used since the 80's as a tool for many applications of UV, soft X rays and hard X rays in condensed matter physics, chemistry and biology. The evolution of SR sources towards higher brightness has led to the design of low-emittance electron storage rings (emittance is the product of beam size and divergence), and the development of special source magnetic structures, as undulators. This means that more and more photons are available on a narrow bandwidth and on a small collimated beam; in other words there is the possibility of getting a high power in a coherent beam. In most applications, a monochromator is used, and the temporal coherence of the light is given by the monochromator bandwidth. With smaller and smaller sources, even without the use of collimators, the spatial coherence of the light has become appreciable, first in the UV and soft X ray range, and then also with hard X rays. This has made possible new or improved experiments in interferometry, microscopy, holography, correlation spectroscopy, etc. In view of these recent possibilities and applications, it is useful to review some basic concepts about spatial coherence of SR, and its measurement and …

The National Ignition Facility (NIF), currently under construction at the Lawrence Livermore National Laboratory, is a stadium-sized facility containing a 192-beam, 1.8-Megajoule, 500-Terawatt, ultraviolet laser system together with a 10-meter diameter target chamber with room for nearly 100 experimental diagnostics. When completed, NIF will be the world's largest and most energetic laser experimental system, providing an international center to study inertial confinement fusion and the physics of matter at extreme energy densities and pressures. NIF's 192 energetic laser beams will compress fusion targets to conditions required for thermonuclear burn, liberating more energy than required to initiate the fusion reactions. Other NIF experiments will allow the study of physical processes at temperatures approaching 10{sup 8} K and 10{sup 11} Bars, conditions that exist naturally only in the interior of stars, planets and in nuclear weapons. NIF has now completed the first phases of its laser commissioning program. The first four beams of NIF have generated 106 kilo-joules of infrared light, exceeding design requirements. Operation of single beams at the second harmonic (531 nm) and third harmonic (351 nm) at greater than 10 kilojoules have also exceeded the performance criteria. NIF's target experimental systems are being commissioned and experiments have begun. This …

We report refined results for the equilibrium constant for water dimerization (K{sub P}), computed as a function of temperature via fully-coupled 6-D calculation of the canonical (H{sub 2}O){sub 2} partition function on VRT(ASP-W)III, the most accurate water dimer potential energy surface currently available. Partial pressure isotherms calculated for a range of temperatures and relative humidities indicate that water dimers can exist in sufficient concentrations (e.g., 10{sup 18}m{sup -3} at 30 C and 100% relative humidity) to affect physical and chemical processes in the atmosphere. The determinations of additional thermodynamic properties ({Delta}G, {Delta}H, {Delta}S, C{sub P}, C{sub V}) for (H{sub 2}O){sub 2} are presented, and the role of quasi-bound states in the calculation of K{sub P} is discussed at length.

Total energies for the six known polymorphs of plutonium metal have been calculated within spin and orbital polarized density-functional theory as a function of lattice constant. Theoretical equilibrium volumes and bulk moduli correspond well with experimental data and the calculated total energies are consistent with the known phase diagram of Pu. It is shown that a preference for formation of magnetic moments, increasing through the {alpha} {yields} {beta} {yields} {gamma} phases, explain their position in the ambient pressure phase diagram and their anomalous variation of atomic density. A simple model is presented that establishes a relationship between atomic density, crystal symmetry, and magnetic moments which is universally valid for all Pu phases.

Scientific progress is becoming increasingly dependent of our ability to study phenomena at multiple scales and from multiple perspectives. The ability to recontextualize third party data within the semantic and syntactic framework of a given research project is increasingly seen as a primary barrier in multi-scale science. Within the Collaboratory for Multiscale Chemical Science (CMCS) project, we are developing a general-purpose informatics-based approach that emphasizes ''on-demand'' metadata creation, configurable data translations, and semantic mapping to support the rapidly increasing and continually evolving requirements for managing data, metadata, and data relationships in such projects. A concrete example of this approach is the design of the CMCS provenance subsystem. The concept of provenance varies across communities, and multiple independent applications contribute to and use provenance. In CMCS, we have developed generic tools for viewing provenance relationships and for using them to, for example, scope notifications and searches. These tools rely on a configurable concept of provenance defined in terms of other relationships. The result is a very flexible mechanism capable of tracking data provenance across many disciplines and supporting multiple uses of provenance information.

Past microlensing experiments such as the MACHO project have discovered the presence of a larger than expected number of microlensing events toward the Large Magellanic Cloud (LMC). These events could represent a large fraction of the dark matter in the halo of our Galaxy, if they are indeed due to halo lenses. However the locations of most of the lenses are poorly defined. The SuperMacho project will detect and follow up {approx}60 microlensing events exhibiting special properties due to binarity, etc., will allow us to better determine the location and nature of the lenses causing the LMC microlensing events.

The {sup 193}Ir(n,n'){sup 193m}Ir cross section for the production of the 80-keV isomer in {sup 193}Ir is evaluated using a combination of experimental data and nuclear reaction modeling, from threshold to about 20 MeV. Four discrete {gamma} lines feeding the isomer were recently observed with the GEANIE {gamma}-ray detector at LANSCE. Theoretical calculations of the nuclear reaction mechanisms in play are then carried out to evaluate the contributions not accounted for in the experimental setup (direct population; fraction of {gamma}-lines not observed in the experiment; etc). Experiment and modeling are then combined to provide a total cross section for the production of the Iridium isomer. We finally compare our result with activation measurement data available for a few energy points.

The evaporation of a range of synthetic pore water solutions representative of the potential high-level-nuclear-waste repository at Yucca Mountain, NV is being investigated. The motivation of this work is to understand and predict the range of brine compositions that may contact the waste containers from evaporation of pore waters, because these brines could form corrosive thin films on the containers and impact their long-term integrity. A relatively complex synthetic Topopah Spring Tuff pore water was progressively concentrated by evaporation in a closed vessel, heated to 95 C in a series of sequential experiments. Periodic samples of the evaporating solution were taken to determine the evolving water chemistry. According to chemical divide theory at 25 C and 95 C our starting solution should evolve towards a high pH carbonate brine. Results at 95 C show that this solution evolves towards a complex brine that contains about 99 mol% Na{sup +} for the cations, and 71 mol% Cl{sup -}, 18 mol% {Sigma}CO{sub 2}(aq), 9 mol% SO{sub 4}{sup 2-} for the anions. Initial modeling of the evaporating solution indicates precipitation of aragonite, halite, silica, sulfate and fluoride phases. The experiments have been used to benchmark the use of the EQ3/6 geochemical code in …

This study examines the effects of burning and granivory on the reproductive success of the rare plant Amsinckia grandiflora (Boraginaceae). Fire is often used in California grasslands as a means of exotic species control, but the indirect effects of these controls on the reproductive ecology of a native plants are rarely assessed. The interaction of fire with granivory of A. grandiflora seeds was examined in California grasslands over five years (1998-2002). In 1998 and 1999, both burned and unburned plots had bird-exclusion (netted) and no-exclusion (open) treatments. Predation rates were high (51-99%) and final predation rates did not differ among treatments. In 2000, granivory rates in the unburned, open plots were lower than in previous years (14%), and rodent trapping yielded only a single animal. Low granivory rates were observed in 2001 for unburned, open plots (47%). In 2001, burned/open plots experienced significantly more granivory (87%) than either burned/netted plots (37%) or unburned/open plots (47%). In 2002, every seed was taken from burned, open plots. Granivory was highly variable, ranging from 4% to 100% per plot over a three-week period. Nearly all plots were discovered (>10% predation) by granivores in all trials in all years. When data from all treatments …