The oceans play a critical role in regulating the global carbon cycle. Deep-ocean waters are roughly 200% supersaturated with CO{sub 2} compared to surface waters, which are in contact with the atmosphere. This difference is due to the flux of photosynthetically derived organic material from surface to deep waters and its subsequent remineralization, i.e. the biological pump''. The pump is a complex phytoplankton-based ecosystem. the paradoxical nature of ocean regions containing high nutrients and low phytoplankton populations has intrigued biological oceanographers for many years. Hypotheses to explain the paradox include the regulation of productivity by light, temperature, zooplankton grazing, and trace metal limitation and/or toxicity. To date, none of the hypotheses, or combinations thereof, has emerged as a widely accepted explanation for why the nitrogen and phosphorus are not depleted in these regions of the oceans. Recently, new evidence has emerged which supports the hypothesis that iron limitation regulates primary production in these areas. This has stimulated discussions of the feasibility of fertilizing parts the Southern Ocean with iron, and thus sequestering additional atmospheric CO{sub 2} in the deep oceans, where it would remain over the next few centuries. The economic, social, and ethical concerns surrounding such a proposition, along …

The GEM EM calorimeter is optimized for the best energy, position, angular resolution and jet rejection. The detailed simulation results are presented. In the barrel with LKr, an energy resolution of about 6%/{radical}{direct_sum}0.4%, pointing resolution of 40mrad/{radical}E + 0.5mrad, and jet rejection of a factor of 5 are expected.

During the recent (12--22 June 1991) Mount Pinatubo volcano eruptions, the US Air Force Global Weather Central (AFGWC) requested assistance of the US Department of Energy`s Atmospheric Release Advisory Capability (ARAC) in creating volcanic ash cloud aviation advisories for the region of the Philippine Islands. Through application of its three-dimensional material transport and diffusion models using AFGWC meteorological analysis and forecast wind fields ARAC developed extensive analysis and 12-hourly forecast ash cloud position advisories extending to 48 hours for a period of five days. The advisories consisted of ``relative`` ash cloud concentrations in ten layers (surface-5,000 feet, 5,000--10,000 feet and every 10,000 feet to 90,000 feet). The ash was represented as a log-normal size distribution of 10--200 {mu}m diameter solid particles. Size-dependent ``ashfall`` was simulated over time as the eruption clouds dispersed. Except for an internal experimental attempt to model one of the Mount Redoubt, Alaska, eruptions (12/89), ARAC had no prior experience in modeling volcanic eruption ash hazards. For the cataclysmic eruption of 15--16 June, the complex three-dimensional atmospheric structure of the region produced dramatically divergent ash cloud patterns. The large eruptions (> 7--10 km) produced ash plume clouds with strong westward transport over the South China Sea, Southeast …

A new mold material has been developed for use in making rare-earth permanent magnet components with precise dimensions in the 10 to 1000 µm range by hot-forging. These molds are made from molds poly(methyl)methacrylate (PMMA) made by deep x-ray lithography (DXRL). An alumina bonded with colloidal silica has been developed for use in these molds. This material can be heated to 950°C without changing dimensions where it develops the strength needed to withstand the hot-fmging conditions (750°C, 100 MPa). In addition, it disintegrates in HF so that parts can be easily removed after forging.

The NIF Power Conditioning System (PCS) is required to deliver -68 kJ to each of the 3840 flashlamp pairs in the NIF laser in a current pulse with a peak of -500 kA and rise time of- 150 µs. The PCS will consist of 192 modules each of which drive 20 lamp-pairs. Each module will basically be a 6 rnF capacitor bank with a nominal charge voltage of 23.5 kV which is switched by a single pressurized air gas switch to 20 RG-220 cables that are connected to individual lamp loads. In addition each module will have a number of subsystems including; a lamp pre-ionization system, power supplies, isolation circuits, trigger systems, safety dump systems, gas system, and an embedded control system. A module will also include components whose primary function is to limit fault currents and thus minimize collateral damage in faults. In the Prototype Development and Testing effort at Sandia National Laboratories all of these were integrated into a single system and proper fimctionality was demonstrated. Extensive testing was done at nominal operating levels into resistive dummy loads and some testing in fault modes was also done. A description of the system and a summary of testing is …

High resolution 2D imaging experiment on the saturated 18.9 nm Ni-like soft X-ray laser is presented. The imaging experiment allows measurement of the absolute output energy and intensity of the X-ray laser, while it gives detailed information on the spatial characteristics of the X-ray laser for understanding the physics and further improving the performance of the X-ray laser.

Simplified models of EBR-II control and safety rods have been developed for core modeling under various operational and shutdown conditions. A parametric study was performed on normal worth, high worth, and safety rod type control rods. A summary of worth changes due to individual modeling approximations is tabulated. Worth effects due to structural modeling simplification are negligible. Fuel region homogenization and burnup compression contributes more than any other factor. Reference case C/E values (ratio of calculated worth from detailed model to measured worth) of 1.072 and 1.142 for safety and normal worth rods indicate acceptable errors when the approximations are used. Fuel burnup effect illustrates rod worth sensitivity to the modeling approximation. Aggregate effects are calculated under a reduced mesh.

Fermilab experiment E866 has performed a precision measurement of the ratio of Drell-Yan yields from 800 GeV/c protons incident on deuterium and hydrogen targets. The measurement is used to determine the ratio of down antiquarks({bar d}) to up antiquarks({bar u}) in the proton over a broad range in the fraction of the proton momentum carried by the antiquark, 0.02 < x < 0.345. For x < 0.15, the data is in reasonable agreement with pre-existing parton distributions while for x > 0.20 the data is much closer to unity than these parton functions had indicated. The light quark asymmetry provides valuable information on the relative role perturbative and non-perturbative mechanisms play in generating the nucleon sea. A proposal to extend the Drell-Yan measurement to higher values of x using 120 GeV protons from the Fermilab main injector will be discussed.

In this paper we describe the difficulties inherent in making accurate, reproducible measurements of message-passing performance. We describe some of the mistakes often made in attempting such measurements and the consequences of such mistakes. We describe mpptest, a suite of performance measurement programs developed at Argonne National Laboratory, that attempts to avoid such mistakes and obtain reproducible measures of MPI performance that can be useful to both MPI implementers and MPI application writers. We include a number of illustrative examples of its use.

Partitioning and transmutation strategies are under study in several countries as a means of reducing the long-term hazards of spent fuel and other high-level nuclear waste. Various reactor and accelerator-driven system concepts have been proposed to transmute the long-lived radioactive nuclei of waste into stable or short-lived species. Among these concepts, the accelerator-driven transmutation of waste (ATW) system has been proposed by LANL for rapid destruction of transuranic actinides and long-lived fission products ({sup 99}Tc and {sup 129}I).The current reference ATW concept employs a subcritical, liquid metal cooled, fast-spectrum nuclear subsystem. Because the discharged fuel is recycled, analysis of ATW nuclear performance requires modeling of the external cycle as well as the in-core fuel management. The fuel cycle analysis of ATW can be performed rigorously using Monte Carlo calculations coupled with detailed depletion calculations. However, the inefficiency of this approach makes it impractical, particularly in view of (a) the large number of fuel cycle calculations needed for design optimization and (b) the need to represent complex in-core and out-of-core fuel cycle operations. To meet the need for design-oriented capabilities, tools previously developed for fast reactor calculations are being adapted for application to ATW. Here we describe the extension and application …

The oceans play a critical role in regulating the global carbon cycle. Deep-ocean waters are roughly 200% supersaturated with CO{sub 2} compared to surface waters, which are in contact with the atmosphere. This difference is due to the flux of photosynthetically derived organic material from surface to deep waters and its subsequent remineralization, i.e. the ``biological pump``. The pump is a complex phytoplankton-based ecosystem. the paradoxical nature of ocean regions containing high nutrients and low phytoplankton populations has intrigued biological oceanographers for many years. Hypotheses to explain the paradox include the regulation of productivity by light, temperature, zooplankton grazing, and trace metal limitation and/or toxicity. To date, none of the hypotheses, or combinations thereof, has emerged as a widely accepted explanation for why the nitrogen and phosphorus are not depleted in these regions of the oceans. Recently, new evidence has emerged which supports the hypothesis that iron limitation regulates primary production in these areas. This has stimulated discussions of the feasibility of fertilizing parts the Southern Ocean with iron, and thus sequestering additional atmospheric CO{sub 2} in the deep oceans, where it would remain over the next few centuries. The economic, social, and ethical concerns surrounding such a proposition, along …

Electron beam temperature, {beta}{perpendicular} (= v{perpendicular}/v), is important to control for the development of high dose flash radiographic bremsstrahlung sources. At high voltage (> 5 MV) increasing electron beam temperature has a serious deleterious effect on dose production. The average and time resolved behavior of beam temperature was measured during radiographic experiments on the HERMES III accelerator (10 MV, 50 kA, 70 ns). A linear array of thermoluminescent dosimeters (TLDs) were used to estimate the time integrated average of beam temperature. On and off-axis photoconducting diamond (PCD) detectors were used to measure the time resolved bremsstrahlung dose rate, which is dependent on beam energy and temperature. The beam temperature can be determined by correlating PCD response with accelerator voltage and current and also by analyzing the ratio of PCD amplitudes on and off axis. This ratio is insensitive to voltage and current and thus, is more reliable than utilizing absolute dose rate. The data is unfolded using comparisons with Monte Carlo simulations to obtain absolute beam temperatures. The data taken on HERMES III show abrupt increases in {beta}{perpendicular} midway through the pulse indicating rapid onset of beam instability.

Theoretical analysis and preliminary experiment on ionization instability of intense laser pulses in ionizing plasmas are presented. The ionization instability is due to the dependence of the ionization rate on the laser intensity and scatters the laser energy off the original propagation direction.

Collaboration is an increasingly important aspect of magnetic fusion energy research. With the increased size and cost of experiments needed to approach reactor conditions, the numbers being constructed has become limited. In order to satisfy the desire for many groups to conduct research on these facilities, we have come to rely more heavily on collaborations. Fortunately, at the same time, development of high performance computers and fast and reliable wide area networks has provided technological solutions necessary to support the increasingly distributed work force without the need for relocation of entire research staffs. Development of collaboratories, collaborative or virtual laboratories, is intended to provide the capability needed to interact from afar with colleagues at multiple sites. These technologies are useful to groups interacting remotely during experimental operations as well as to those involved in the development of analysis codes and large scale simulations The term ``collaboratory`` refers to a center without walls in which researchers can perform their studies without regard to geographical location - interacting with colleagues, accessing instrumentation, sharing data and computational resources, and accessing information from digital libraries [1],[2]. While it is widely recognized that remote collaboration is not a universal replacement for personal contact, it does …

Colloidal suspensions of Si0{sub 2} in ethanol prepared by the ammonia catalyzed hydrolysis of tetraethyl silicate (TEOS) in ethanol have been routinely used for over 10 years to prepare antireflective (AR) coatings on the fused silica transmissive optical components of high power fusion lasers. Very high purity coatings are required to avoid laser damage and these are obtained when the TEOS is fractionally distilled under N{sub 2} prior to use. Recently we found that products from aerial oxidation of distilled TEOS, had a significant effect on the particle size of our coating suspensions to the detriment of the optical performance. We require particle sizes less than 20 nm to avoid light loss due to scatter and contaminated TEOS gave suspensions with much higher particle sizes. Oxidation products were identified by GC mass spectroscopy and included acetaldehyde, acetic acid, silicon acetates and reaction products of these compounds with ethanol. Acetic acid and silicon acetates were found to be the major cause of large particle formation. These could be removed by careful redistillation preferably in the presence of a small quantity of magnesium ethoxide. Storage in sealed containers over N{sub 2} avoided further problems.

An improved understanding of strongly-driven laser plasma coupling is important for optimal use of the National Ignition Facility (NIF) for both inertial fusion and for a variety of advanced applications. Such applications range from high energy x- ray sources and high temperature hohlraums to fast ignition and laser radiography. We discuss a novel model for the scaling of strongly-driven stimulated Brillouin and Raman scattering. This model postulates an intensity dependent correlation length associated with spatial incoherence due to filamentation and stimulated forward scattering. We first motivate the model and then relate it to a variety of experiments. Particular attention is paid to high temperature hohlraum experiments, which exhibited low to modest stimulated Brillouin scattering even though this instability was strongly driven. We also briefly discuss the strongly nonlinear interaction physics for efficient generation of high energy electrons either _ by irradiating a large plasma with near quarter-critical density or by irradiating overdense targets with ultra intense laser

Hypereutectoid steels have the potential for dramatically increasing the strength of wire used in tire cord and in other high strength wire applications. The basis for this possible breakthrough is the elimination of a brittle proeutectoid network that can form along grain boundaries if appropriate processing procedures and alloy additions are used. A review is made of work done by Japanese and other researchers on eutectoid and mildly hypereutectoid wires. A linear extrapolation of the tensile strength of fine wires predicts higher strengths at higher carbon contents. The influence of processing, alloy additions and carbon content in optimizing the strength, ductility and fracture behavior of hypereutectoid steels is presented. It is proposed that the tensile strength of pearlitic wires is dictated by the fracture strength of the carbide lamella at grain boundary locations in the carbide. Methods to improve the strength of carbide grain boundaries and to decrease the carbide plate thickness will contribute to enhancing the ultrahigh strength obtainable in hypereutectoid steel wires. 23 refs., 13 figs., 1 tab.

This presentation details the success of the cooperative efforts to develop fish rearing projects at the Hanford Site, Richland,WA.

This paper will discuss some basic technical information resources that would be helpful to the novice nuclear criticality safety specialist. These include bibliographic and benchmark compilations, handbooks, and online resources. The specialist should also be familiar with benchmark quality experimental data needed for code validation. This paper will also discuss the critical experiment data obtained in the 1950s and 1960s at the Lawrence Livermore National Laboratory.

Optical component specifications for the high-average-power lasers and transport system used in the Atomic Vapor Laser Isotope Separation (AVLIS) plant must address demanding system performance requirements. The need for high performance optics has to be balanced against the practical desire to reduce the supply risks of cost and schedule. This is addressed in optical system design, careful planning with the optical industry, demonstration of plant quality parts, qualification of optical suppliers and processes, comprehensive procedures for evaluation and test, and a plan for corrective action.

As part of efforts to develop a three-dimensional failure model for composites, a study of failure and fatigue due to combined interlaminar stresses was conducted. The combined stresses were generated using a hollow cylindrical specimen, which was subjected to normal compression and torsion. For both glass and carbon fiber composites, normal compression resulted in a significant enhancement in the interlaminar shear stress and strain at failure. Under moderate compression levels, the failure mode transitioned from elastic to plastic. The observed failure envelope could not be adequately captured using common ply- level failure models. Alternate modeling approaches were examined and it was found that a pressure-dependent failure criterion was required to reproduce the experimental results. The magnitude of the pressure-dependent terms of this model was found to be material dependent. The interlaminar shear fatigue behavior of a carbon/epoxy system was also studied using the cylindrical specimen. Preliminary results indicate that a single S/N curve which is normalized for interlaminar shear strength may be able to reproduce the effects of both temperature and out-of-plane compression on fatigue life. The results demonstrate that there are significant gains to be made in improving interlaminar strengths of composite structures by applying out-of-plane compression. This effect …

The authors present a technique for deriving predictions for the run times of parallel applications from the run times of similar applications that have executed in the past. The novel aspect of the work is the use of search techniques to determine those application characteristics that yield the best definition of similarity for the purpose of making predictions. They use four workloads recorded from parallel computers at Argonne National Laboratory, the Cornell Theory Center, and the San Diego Supercomputer Center to evaluate the effectiveness of the approach.They show that on these workloads the techniques achieve predictions that are between 14 and 60% better than those achieved by other researchers; the approach achieves mean prediction errors that are between 41 and 65% of mean application run times.

Simple statistical mechanics models have been assembled into a wide-range equation of state for the hydrogen isotopes. The solid is represented by an Einstein-Grtineisen model delimited by a Lindemann melting curve. The fluid is represented by an ideal gas plus a soft-sphere fluid configurational term. Dissociation and ionization are approximated by modifying the ideal gas chemical-equilibrium formulation. The T = 0 isotherm and dissociation models have been fitted to new diamond-anvil isotherm and laser-generated shock data. The main limitation of the model is in ionization at high compression.

The integration of PZT and SBT film-based capacitors with Si integrated circuit technology requires the use of processing steps that may degrade the performance of individual device components. Hydrogen annealing to remove damage in the Si FET adversely affects both PZT and SBT, although the mechanisms of degradation are different. We have used Mass spectroscopy of recoiled ions (MSRI), X-ray diffraction (XRD), Raman spectroscopy and electrical characterization to study the mechanisms of hydrogen-induced degradation in these two materials. The mechanism responsible for degradation in SBT during hydrogen annealing appears to be hydrogen-induced volatilization of Bi from the near-surface region during film growth. Although there is a similar, but smaller, loss of Pb in PZT, the resulting change in stoichiometry is not responsible for the degradation of the ferroelectric properties. Raman spectroscopy reveals that PZT films exposed to hydrogen exhibit evidence for the formation of polar hydroxyl [OH-] bonds, which can block the movement of ions in the lattice and inhibit polarization. The possible sites for the incorporation of hydrogen are discussed in terms of ionic radii, and crystal structure.