Article is a correction to an error in the original publication. The enzymatic step catalyzed by oxophytodienoic acid reductase 3 was misstated. A correction has been made to Section 2. Results and Discussion, Subsection 2.13. Lipids of Plants with Mutations in Lipid-Related Genes, Paragraph 1.

Article develops Trichoderma reesei (Hypocrea jecorina) as a microbial cell factory for the heterologous expression of fungal secondary metabolites.

This scenario proposes establishment of test and engineering facilities to (1) investigate the technological problems associated with laser fusion, (2) demonstrate fissile fuel production, and (3) demonstrate competitive electrical power production. Such facilities would be major milestones along the road to a laser-fusion power economy. The relevant engineering and economic aspects of each of these research and development facilities are discussed. Pellet design and gain predictions corresponding to the most promising laser systems are presented for each plant. The results show that laser fusion has the potential to make a significant contribution to our energy needs. Beginning in the early 1990's, this new technology could be used to produce fissile fuel, and after the turn of the century it could be used to generate electrical power.

The extent to which finite element models of partially buried nuclear power plant structures may be used to compute seismic induced wall pressures is investigated in this paper. Stresses in three dimensional finite elements modeling the soil adjacent to the structure are used and stresses in these elements are used to evaluate wall pressures. Depths of burial of the structure varying from 1/4 to 1 times the height of the structure are considered. The SASSI computer code is used to perform the analyses. The wall pressures for the shallower depths of burial are found to depend on the inertial interaction loads, while the pressures for the deeper embedded structures are found to depend on kinematic interaction loads. The input ground motion for the study has a ZPA equal to 0.3 g. The maximum wall pressures are examined to determine whether non linear effects (separation of the wall and soil or slippage of the soil relative to the wall) are important. Non-linear effects are found to occur for depths of burial less than one half of the height and are found to occur over one half of the buried depth.

The Joint URBAN 2003 field experiment took place in Oklahoma City, Oklahoma, during July 2003 to explore the effect of an urban canopy on the transport and diffusion of a passive tracer released in an urban area. Over one hundred three-dimensional sonic anemometers were deployed in and around the urban area to monitor wind speed, direction, and turbulence during releases of SF6. Deployment locations include a profile of eight sonic anemometers mounted on a crane located 1 km north (typically downwind) of the central business district, and several surface meteorological towers within an urban canyon.

Published thermodynamic data yielding the osmotic coefficients, relative apparent molar enthalpies, and apparent molar heat capacities of Mg(NO{sub 3}){sub 2}(aq) have been collected, recalculated consistently, and critically assessed. The more reliable of these data have been used to evaluate the parameters of the standard three-parameter form of Pitzer's ion-interaction model to higher molalities than previously available, along with the parameters of Archer's four-parameter, extended ion-interaction model, at 298.15 K. Published experimental thermodynamic data were essentially represented equally well by these two models, provided that the exponential coefficient {alpha}{sub 1} of the standard Pitzer model is fixed at the optimum value of {alpha}{sub 1} = 1.55 kg{sup -1/2} x mol{sup -1/2} rather than the traditional value of {alpha}{sub 1} = 2.0 kg{sup -1/2} x mol{sup -1/2} The use of the standard Pitzer model with this modified {alpha}{sub 1} value is recommended for Mg(NO{sub 3}){sub 2}(aq). In addition, an empirical equation is given for the variation of the water activity of a saturated solution with temperature, from 273.54 to 328.20 K, with Mg(NO{sub 3}){sub 2}(aq) x 6H{sub 2}O(s) as the solid phase.

Experimentation, theory, and modeling have all played vital roles in defining what is known about microstructural evolution and the effects of microstructure on material properties. Recently, technology has become an enabling factor, allowing significant advances to be made on several fronts. Experimental evidence of crystallographic slip and the basic theory of crystal plasticity were established in the early 20th century, and the theory and models evolved incrementally over the next 60 years. During this time, modeling was primarily concerned with the average response of polycrystalline aggregates. While some detailed finite element modeling (FEM) with crystal plasticity constitutive relations was performed in the early 1980's, such simulations over taxed the capacity of the available computer hardware. Advances in computer capabilities led to a flurry of activity in finite element modeling in the next 10 years, thus increasing understanding of lattice orientation evolution and generating detailed predictions of spatial orientation distributions that could not be readily validated with existing experimental characterization methods. Significant advancements in material characterization, particularly automated electron backscatter diffraction (EBSD), have made it possible to conduct detailed validation studies of the FEM predictions. The data collected are extensive, and many questions about the evolution of microstructure and its role …

The main function of the RHIC cryogenic system is to maintain the superconducting magnets in the two rings of the new collider-accelerator at Brookhaven National Laboratory at or below 4.5K. The main feature in the RHIC cryogenic system is the helium refrigerator. A new process control philosophy was implemented that allows this system to track the actual load from the accelerator rings and lets it respond accordingly. The refrigerator capacity decreases as the load decreases and increases as the load increases. This has resulted in the following improvements in the operation of the system: (1) Higher reliability because the rotating equipment does not have to run at full load continuously. (2) Greater stability because the system tracks the load continuously and responds quickly to any transients such as a quench. (3) Reduced power consumption because the discharge pressure of the system is adjusted continuously to match the load; therefore, the compressors draw less power when the load fi-om the accelerator rings decreases. This paper also addresses other modifications introduced that added to the efficiency, stability, and reliability of the system. As a result of this upgrade the Carnot efficiency of the refrigerator system has increased to 15% from around 10%.

The authors compare two algorithms for solving the equations of unsteady inviscid compressible flow in an Eulerian frame: a staggered grid, Lagrange plus remap artificial viscosity scheme and a cell-centered, direct Eulerian higher-order Godunov scheme. They use the two methods to compute solutions to a number of one- and two-dimensional problems. The results show the accuracy of the two schemes to be generally equivalent. In a 1984 survey paper by Woodward and Colella, the Lagrange plus remap approach did not compare favorably with the higher-order Godunov methodology. They examine, therefore, how certain features of the staggered grid scheme considered here contribute to its improved accuracy. The critical features are shown to be the use of a monotonic artificial viscosity in the Lagrange step and, in the remap step, the use of a corner transport upwind scheme with van Leer limiters in conjunction with separate advection of internal and kinetic energies.

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This paper presents a divide-and-conquer ray-traced volume rendering algorithm and its implementation on networked workstations and a massively parallel computer, the Connection Machine CM-5. This algorithm distributes the data and the computational load to individual processing units to achieve fast, high-quality rendering of high-resolution data, even when only a modest amount of memory is available on each machine. The volume data, once distributed, is left intact. The processing nodes perform local ray-tracing of their subvolume concurrently. No communication between processing units is needed during this locally ray-tracing process. A subimage is generated by each processing unit and the final image is obtained by compositing subimages in the proper order, which can be determined a priori. Implementations and tests on a group of networked workstations and on the Thinking Machines CM-5 demonstrate the practicality of our algorithm and expose different performance tuning issues for each platform. We use data sets from medical imaging and computational fluid dynamics simulations in the study of this algorithm.

The TVA/EPRI Tailored Collaborative Project {open_quotes}Biotransformation of Polychlorinated Biphenyls (PCBS) in Contaminated Soils{close_quotes}, has as its objective biotransformation of PCB contaminated soils at utility sites (Phase I Report March 1992). However, there is recognition of the existence of other types of nonmetabolic alterations of PCBs in the contaminated soils. Of these nonmetabolic alterations, photoalteration is of special interest to the project. Photoalteration has the potential for enhancing PCB transformation with little intervention and little harm to the microbial community. PCBs have pervaded the environment, and the paucity of knowledge about their chemistry is becoming readily apparent. Although PCBs are quite resistant to degradation, photolysis, which is a chemical decomposition process that is induced by radiant energy, may be important in the environmental chemistry of PCBS. The photochemical degradation of PCBs may affect atmospheric levels of contaminants and photolabile chemicals that reside in water bodies or on surfaces, as for example, on leaves and vegetation. Chemicals present in the environment can undergo direct or indirect phototransformation which includes photosensitized degradation and oxygenation as well as photoinduced degradation. Photoalteration is produced by either artificial light or by light from the sun. Ultraviolet radiation (UV) is known to induce chemical reactions in many …

Uranium enrichment processes have the capability of producing weapons-grade material in the form of highly enriched uranium. Thus, detection of undeclared uranium enrichment activities is an international safeguards concern. The uranium separation technologies currently in use employ UF{sub 6} gas as a separation medium, and trace quantities of enriched uranium are inevitably released to the environment from these facilities. The isotopic content of uranium in the vegetation, soil, and water near the plant site will be altered by these releases and can provide a signature for detecting the presence of enriched uranium activities. This paper discusses environmental sampling and analytical procedures that have been used for the detection of uranium enrichment facilities and possible safeguards applications of these techniques.

We report here the first observation of inclusive {Lambda}{sup 0}, {bar {Lambda}}{sup 0}, K{sub s}{sup 0} production in nucleus-nucleus collisions at 14.5 GeV/n. 11 refs., 6 figs.

Transfer coefficients to predict the passage of isotopes from the environment to terrestrial foods have been derived for various radionuclides of importance in the nuclear fuel cycle. These data update and extend previously recommended handbook values. We derive transfer coefficients to terrestrial foods and describe the systematics of the derived transfer coefficients. Suggestions are offered for changes in the values of transfer coefficients to terrestrial foods that now appear in federal regulatory guides. Deficiencies in our present knowledge concerning transfer coefficients and limitations in the use of these values to ensure compliance with radiation protection standards are discussed.

The Mirror Fusion Test Facility (MFTF-B) now under construction at Lawrence Livermore National Laboratory represents more than an order-of-magnitude step from earlier magnetic-mirror experiments toward a future mirror fusion reactor. In fact, when the device begins operating in 1986, the Lawson criteria of ntau = 10/sup 14/ cm/sup -3/.s will almost be achieved for D-T equivalent operation, thus signifying scientific breakeven. Major steps have been taken to develop MFTF-B technologies for tandem mirrors. Steady-state, high-field, superconducting magnets at reactor-revelant scales are used in the machine. The 30-s beam pulses, ECRH, and ICRH will also introduce steady-state technologies in those systems.

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To minimize the radiological risk from the operation of a waste management system for the safe disposal of high-level waste, performance characteristics of the solidified waste form must be specified. The minimum waste form characteristics that must be specified are the radionuclide volatilization fraction, airborne particulate dispersion fraction, and the aqueous dissolution characteristics. The results indicate that the pre-emplacement environs are more limiting in establishing the waste form performance criteria than the post-emplacement environs. The actual values of expected risk are sensitive to modeling assumptions and data base uncertainties. The transportation step appears to be the most limiting in determining the required performance characteristics.

We present a valence-state model to explain the characteristics of a recently observed pre-edge feature in Mn L{sub 3} x-ray magnetic circular dichroism (XMCD) of ferromagnetic (Ga,Mn)As and (Al,Ga,Mn)As thin films. The prepeak XMCD shows a uniaxial anisotropy, contrary to the cubic symmetry of the main structures induced by the crystalline electric field. Reversing the strain in the host lattice reverses the sign of the uniaxial anisotropy. With increasing carrier localization, the prepeak height increases, indicating an increasing 3d character of the hybridized holes. Hence, the feature is ascribed to transitions from the Mn 2p core level to unoccupied p-d hybridized valence states. The characteristics of the prepeak are readily reproduced by the model calculation taking into account the symmetry of the strain-, spin-orbit-, and exchange-split valence states around the zone center.

This article investigates whether the correct number of classes can still be retrieved when a higher level of nesting in multilevel growth mixture model (MGMM) is ignored.

This article assesses the potential for basin geology and local limnological conditions to predict stable carbon and nitrogen isotope values of six carbon sources at multiple locations in four Neotropical floodplain ecosystems (Paranaá , Pantanal, Araguaia, and Amazon).

As we observe the 200th anniversary of Charles Darwin's birthday, microbiologists interested in the application of Darwin's ideas to the microscopic world have a lot to celebrate: an emerging picture of the (mostly microbial) Tree of Life at ever-increasing resolution, an understanding of horizontal gene transfer as a driving force in the evolution of microbes, and thousands of complete genome sequences to help formulate and refine our theories. At the same time, quantitative models of the microevolutionary processes shaping microbial populations remain just out of reach, a point that is perhaps most dramatically illustrated by the lack of consensus on how (or even whether) to define bacterial species. We summarize progress and prospects in bacterial population genetics, with an emphasis on detecting the footprint of positive Darwinian selection in microbial genomes.

Nanostructures constructed from metal and semiconductor nanocrystals conjugated to, and organized by DNA are an emerging class of material with collective optical properties. We created discrete pyramids of DNA with gold nanocrystals at the tips. By taking small angle X-ray scattering (SAXS) measurments from solutions of these pyramids we confirmed that this pyramidal geometry creates structures which are more rigid in solution than linear DNA. We then took advantage of the tetrahedral symmetry to demonstrate construction of chiral nanostructures.

At high baryon number density, it has been proposed that a new phase of QCD matter controlsthe physics. This matter is confining but can have densities much larger than 3QCD. Its existenceis argued from large Nc approximations, and model computations. It is approximately chirallysymmetric.