Deep-sea coral communities have long been recognized by fisherman as areas that support large populations of commercial fish. As a consequence, many deep-sea coral communities are threatened by bottom trawling. Successful management and conservation of this widespread deep-sea habitat requires knowledge of the age and growth rates of deep-sea corals. These organisms also contain important archives of intermediate and deep-water variability, and are thus of interest in the context of decadal to century-scale climate dynamics. Here, we present {Delta}{sup 14}C data that suggest that bamboo corals from the Gulf of Alaska are long-lived (75-126 years) and that they acquire skeletal carbon from two distinct sources. Independent verification of our growth rate estimates and coral ages is obtained by counting seasonal Sr/Ca cycles and probable lunar cycle growth bands.

We examine an application of the Gillespie algorithm to simulating spatially inhomogeneous reaction-diffusion systems in mesoscopic volumes such as cells and microchambers. The method involves discretizing the chamber into elements and modeling the diffusion of chemical species by the movement of molecules between neighboring elements. These transitions are expressed in the form of a set of reactions which are added to the chemical system. The derivation of the rates of these diffusion reactions is by comparison with a finite volume discretization of the heat equation on an unevenly spaced grid. The diffusion coefficient of each species is allowed to be inhomogeneous in space, including discontinuities. The resulting system is solved by the Gillespie algorithm using the fast direct method. We show that in an appropriate limit the method reproduces exact solutions of the heat equation for a purely diffusive system and the nonlinear reaction-rate equation describing the cubic autocatalytic reaction.

A new approach to the study of material strength of metals at extreme pressures has been developed on the Omega laser, using a ramped plasma piston drive. The laser drives a shock through a solid plastic reservoir that unloads at the rear free surface, expands across a vacuum gap, and stagnates on the metal sample under study. This produces a gently increasing ram pressure, compressing the sample nearly isentropically. The peak pressure on the sample, inferred from VISAR measurements of velocity, can be varied by adjusting the laser energy and pulse length, gap size, and reservoir density, and obeys a simple scaling relation. In an important application, using in-flight x-ray radiography, the material strength of solid-state samples at high pressure can be inferred by measuring the reductions in the growth rates (stabilization) of Rayleigh-Taylor (RT) unstable interfaces. This paper reports the first attempt to use this new laser-driven, quasi-isentropic technique for determining material strength in high-pressure solids. Modulated foils of Al-6061-T6 were accelerated and compressed to peak pressures of 200 kbar. Modulation growth was recorded at a series of times after peak acceleration and well into the release phase. Fits to the growth data, using a Steinberg-Guinan (SG) constitutive strength …

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The fast ignition (FI) concept requires the generation of a compact, dense, pure fuel mass accessible to an external ignition source. The current baseline FI target is a shell fitted with a reentrant cone extending to near its center. Conventional direct or indirect drive collapses the shell near the tip of the cone and then an ultra-intense laser pulse focused to the inside cone tip generates high-energy electrons to ignite the dense fuel. We have theoretically and experimentally investigated the collapse of such targets, validating modeling and exploring the tradeoffs available, in such an asymmetric geometry, to optimize compaction of the fuel and maintain the integrity of the cone. The collapse is complex. Away from the cone, the shell collapses much as does a conventional implosion, generating a hot, low-density inner core. But because of the open side hot plasma exhausts out toward the tip of the cone. This hot plasma is advantageous for implosion diagnostics; it can provide protons for angular dependent measurements of the shell wall, neutrons for temperature measurements, and self-emission for contamination measurements. But for FI it is a liability; the hot, low-density inner core impedes the compaction of the cold fuel, lowering the implosion/burn efficiency …

Target designs are described that are meant to achieve ignition on the National Ignition Facility. Simulations of recent indirect drive cryogenic capsule designs indicate dramatically reduced growth of short wavelength hydrodynamic instabilities, resulting from two changes in the designs. First, better optimization results from systematic mapping of the ignition target performance over the parameter space of ablator and DT-ice thickness combinations, using techniques developed by one of us (Herrmann). After the space is mapped with one-dimensional simulations, exploration of it with two-dimensional simulations quantifies the dependence of instability growth on target dimensions. Low modes and high modes grow differently in different regions of the space, allowing a trade-off of the two regimes of growth. Significant improvement in high-mode stability can be achieved, relative to previous designs, with only insignificant increase in low-mode growth. This procedure produces capsule designs that, in simulations, tolerate several times the surface roughness that could be tolerated by capsules optimized by older more heuristic techniques. Another significant reduction in instability growth, by another factor of several, is achieved with ablators with 'graded dopants.' In this type of capsule the mid-Z dopant, which is needed in the ablator to minimize x-ray preheat at the ablator-ice interface, is …

In celebration of John von Neumann's 100th birthday, a series of four lectures were presented on the evening of February 10, 2003 during the SIAM Conference on Computational Science and Engineering in San Diego. The venue was appropriate because von Neumann spent much of the later part of his life, in the 1950's, as an unofficial ambassador for computational science. He was then the only senior American scientist who had experience with the new computers (digital, electronic, and programmable) and a vision of their future importance. No doubt he would have relished the chance to attend a meeting such as this. The first speaker, William Aspray, described the ''interesting times'' during which computers were invented. His remarks were based on his history [1] of this period in von Neumann's life. We were honored to have John von Neumann's daughter, Marina von Neumann-Whitman, as our second speaker. Other accounts of von Neumann's life can be found in books by two of his colleagues [2] and [3]. Our third speaker, Peter Lax, provided both mathematical and international perspectives on John von Neumann's career. Finally, Pete Stewart spoke about von Neumann's numerical error analysis [4] in the context of later work; this talk …

Simulation results are presented that illustrate the formation and decay of a spheromak plasma driven by a coaxial electrostatic plasma gun, and that model the energy confinement of the plasma. The physics of magnetic reconnection during spheromak formation is also illuminated. The simulations are performed with the three-dimensional, time-dependent, resistive magnetohydrodynamic NIMROD code. The dimensional, simulation results are compared to data from the SSPX spheromak experiment at the Lawrence Livermore National Laboratory. The simulation results are tracking the experiment with increasing fidelity (e.g., improved agreement with measurements of the magnetic field, fluctuation amplitudes, and electron temperature) as the simulation has been improved in its representations of the geometry of the experiment (plasma gun and flux conserver), the magnetic bias coils, and the detailed time dependence of the current source driving the plasma gun, and uses realistic parameters. The simulations are providing a better understanding of the dominant physics in SSPX, including when the flux surfaces close and the mechanisms limiting the efficiency of electrostatic drive.

The production of supersonic jets of material via the interaction of a strong shock wave with a spatially localized density perturbation is a common feature of inertial confinement fusion and astrophysics. The behavior of two-dimensional (2D) supersonic jets has previously been investigated in detail [J. M. Foster et. al, Phys. Plasmas 9, 2251 (2002)]. In three-dimensions (3D), however, there are new aspects to the behavior of supersonic jets in compressible media. In this paper, the commissioning activities on the National Ignition Facility (NIF) [J. A. Paisner et al., Laser Focus World 30, 75 (1994)] to enable hydrodynamic experiments will be presented as well as the results from the first series of hydrodynamic experiments. In these experiments, two of the first four beams of NIF are used to drive a 40 Mbar shock wave into millimeter scale aluminum targets backed by 100 mg/cc carbon aerogel foam. The remaining beams are delayed in time and are used to provide a point-projection x-ray backlighter source for diagnosing the three-dimensional structure of the jet evolution resulting from a variety of 2D and 3D features. Comparisons between data and simulations using several codes will be presented.

A warm, relativistic fluid theory of a nonequilibrium, collisionless plasma is developed to analyze nonlinear plasma waves excited by intense drive beams. The maximum amplitude and wavelength are calculated for nonrelativistic plasma temperatures and arbitrary plasma wave phase velocities. The maximum amplitude is shown to increase in the presence of a laser field. These results set a limit to the achievable gradient in plasma-based accelerators.

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Results are presented from the 3D electromagnetic turbulence code BOUT, the 2D transport code UEDGE, and theoretical analysis of boundary turbulence and transport in a real divertor-plasma geometry and its relationship to the density limit. Key results include: (1) a transition of the boundary turbulence from resistive X-point to resistive-ballooning as a critical plasma density is exceeded; (2) formation of an X-point MARFE in 2D UEDGE transport simulations for increasing outboard radial transport as found by BOUT for increasing density; (3) formation of a density pedestal due to neutral fueling; (4)identification of convective transport by localized plasma 'blobs' in the SOL at high density and decorrelation of turbulence between the midplane and the divertor leg due to strong X-point magnetic shear; (5) a new divertor-leg instability driven by a radial tilt of the divertor plate.

Many differences exist in Department of Energy (DOE) and Nuclear Regulatory Commission (NRC) Quality Assurance (QA) requirements documents, work scope, organizational structures, and graded application and assessment approaches. These differences must be understood and reconciled to ensure consistent and effective implementation and cost effective assessments of QA Programs for DOE organizations participating in the design, purchase, fabrication, handling, shipping, storing, cleaning, assembly, inspection, testing, operation, maintenance, repair, use and/or modification of the radioactive material packaging. This paper discusses those differences and provides practical recommendations that can serve as stepping stones to more effective and efficient QA programs and value added assessments at DOE sites participating in radioactive material packaging activities.

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A nominal 1500 STP-L PAssively Cooled, Electrically heated hydride (PACE) Bed has been developed for implementation into a new Savannah River Site tritium project. The 1.2 meter (four-foot) long process vessel contains an internal ''U-tube'' for tritium In-Bed Accountability (IBA) measurements. IBA will be performed on six, 12.6 kg production metal hydride storage beds. IBA tests were done on a prototype bed using electric heaters to simulate the radiolytic decay of tritium. Tests had gas flows from 10 to 100 SLPM through the U-tube or 100 SLPM through the bed's vacuum jacket. IBA inventory measurement errors at the 95 percent confidence level were calculated using the correlation of IBA gas temperature rise, or (hydride) bed temperature rise above ambient temperature, versus simulated tritium inventory. Prototype bed IBA inventory errors at 100 SLPM were the largest for gas flows through the vacuum jacket: 15.2 grams for the bed temperature rise and 11.5 grams for the gas temperature rise. For a 100 SLPM U-tube flow, the inventory error was 2.5 grams using bed temperature rise and 1.6 grams using gas temperature rise. For 50 to 100 SLPM U-tube flows, the IBA gas temperature rise inventory errors were nominally one to two grams …

This investigation examines the interface atomic structure and bonding characteristics in an advanced ceramic, obtaining new and unique experimental information that will help to understand and improve the properties of ceramics. Unique direct atomic resolution images have been obtained that illustrate how a range of rare-earth atoms bond to the interface between the intergranular phase and the matrix grains in an advanced silicon nitride ceramic. It has been found that each rare-earth atom bonds to the interface at a different location, depending on atom size, electronic configuration and the presence of oxygen at the interface. This is the key factor to understanding the origin of the mechanical properties in these ceramics and will enable precise tailoring in the future to critically improve the materials performance in wide-ranging applications.

A 38 cm (15 inch) long metal hydride bed fabricated using 11.4 cm (4.5 inch) O.D., standard schedule 316/316L stainless steel pipe was fitted with 22 strain gauges to measure tangential and longitudinal stress resulting from hydride absorption and desorption cycling. Tests were conducted using two different LaNi4.25Al0.75 metal hydride fill-levels in the bed. Tests conducted with hydride filled to two-thirds (1.75L) of the 2.63L total bed volume resulted in a maximum stress less than one-third of the pipe's ASME Code allowable, for hydride absorption up to a hydrogen-to-metal ratio (H/M) of 0.86. After 15 absorption/desorption tests and hydride passivation, examination of the bed interior revealed a significant decrease in particle size and increase in hydride height. The second fill level had 0.4L of fresh hydride added to the bed's cycled hydride material, and 56 absorption/desorption tests, up to a gas loading of 0.83 H/M performed. Second fill tests resulted in maximum stresses less than 40 percent of the ASME Code allowable. Post-test bed radiographs showed a further increase in the apparent hydride fill height, and internal component deformation.

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This study developed a probabilistic methodology for assessment of the reliability and security of electrical energy distribution networks. This included consideration of the future grid system, which will rely heavily on the existing digitally based communication infrastructure for monitoring and protection. Event tree and fault tree methods were utilized. The approach extensively modeled the types of faults that a grid could potentially experience, the response of the grid, and the specific design of the protection schemes. We demonstrated the methods by applying it to a small sub-section of a hypothetical grid based on an existing electrical grid system of a metropolitan area. The results showed that for a typical design that relies on communication network for protection, the communication network reliability could contribute significantly to the frequency of loss of electrical power. The reliability of the communication network could become a more important contributor to the electrical grid reliability as the utilization of the communication network significantly increases in the near future to support ''smart'' transmission and/or distributed generation.

This paper was originally written in response to the concern that rising levels of CO2 in the atmosphere caused by burning of fossil fuels will ultimately contribute to global warming. Now we are beginning to see evidence of coming problems in the supply of fuels for transportation. This paper describes the benefits of adequate energy supply and the problems of future energy supply. Partial solutions are suggested for immediate application as well as longer term solutions to address both of these concerns. To evaluate the situation and solutions we must understand: (1) how much primary energy is currently used world-wide and might be needed in 2100, (2) how important energy is to the welfare of people, (3) the forms of energy sources and end uses and (4) where new sources may come from. The major portion of world primary energy demand is provided by fossil fuels. This portion dropped from 93% in 1970 to 85% in 1995, mainly because of the increased use of nuclear energy. How ever, since the mid-1990s fossil fuels have maintained their 85% share of world energy supply. The importance of the relationship between per capita energy consumption and per capita income for the world is …

Recent experimental results have provided unambiguous evidence that neutrinos have a small but finite mass and mix from one type into another. The phenomenon of neutrino mixing is characterized by the coupling between the neutrino flavor (nu e,mu,tau) and mass eigenstates (nu 1,2,3) and the associated mixing angles. Previous neutrino oscillation experiments have determined two of the three mixing angles in the neutrino mixing matrix, U MNSP. Using multiple neutrino detectors placed at different distances from a nuclear power plant, a future reactor neutrino experiment has the potential to discover and measure the coupling of the electron neutrino flavor to the third mass eigenstate, Ue3, the last undetermined element of the neutrino mixing matrix. In this paper we describe recent efforts in the US towards a next-generation experiment to measure theta13 with reactor neutrinos.

Horizontal path correction of optical beam propagation presents a severe challenge to adaptive optics systems due to the short transverse coherence length and the high degree of scintillation incurred by propagation along these paths. The system presented operates with nearly monochromatic light. It does not require a global reconstruction of the phase, thereby eliminating issues with branch points and making its performance relatively unaffected by scintillation. The systems pixel count, 1024, and relatively high correction speed, in excess of 800 Hz, enable its use for correction of horizontal path beam propagation. We present results from laboratory and field tests of the system in which we have achieved Strehl ratios greater than 0.5.

With residential areas moving closer to military training sites, the effects upon the environment and neighboring civilians due to dust generated by training exercises has become a growing concern. Under a project supported by the Strategic Environmental Research and Development Program (SERDP) of the Department of Defense, a custom application named DUSTRAN is currently under development that integrates a system of EPA atmospheric dispersion models with the ArcGIS application environment in order to simulate the dust dispersion generated by a planned training maneuver. This integration between modeling system and GIS application allows for the use of real world geospatial data such as terrain, land-use, and domain size as input by the modeling system. Output generated by the modeling system, such as concentration and deposition plumes, can then be displayed upon accurate maps representing the training site. This paper discusses the development of this integration between modeling system and Arc GIS application.