New or modified models have been proposed for the much-studied Si(111)-(2x1) surface structure, including: a reverse-tilted p-bonded chain model (by Zitzlsperger et al); a three-bond scission model (by Haneman et al); and a p-bonded chain model with enhanced vibrations (present work). These models are compared here to the generally accepted modified p-bonded chain model (by Himpsel et al, 1984), by analyzing low-energy electron diffraction (LEED) I-V curves measured earlier. Using the efficient automated tensor LEED technique, the models can be refined to a much greater degree than with earlier methods of LEED analysis. This study distinctly favors the earlier modified p-bonded chain model, but with strongly enhanced vibrations. To compare models that have different numbers of adjustable free parameters a Hamilton ratio test is used: it can distinguish between improvement due to a better model and improvement due only to more parameters.

This paper discusses an innovative application of new Markov localization techniques that combat the problem of odometry drift, allowing a novel control architecture developed at the Idaho National Engineering and Environmental Laboratory (INEEL) to be utilized within a sensor characterization facility developed at the Remote Sensing Laboratory (RSL) in Nevada. The new robotic capability provided by the INEEL will allow RSL to test and evaluate a wide variety of sensors including radiation detection systems, machine vision systems, and sensors that can detect and track heat sources (e.g. human bodies, machines, chemical plumes). By accurately moving a target at varying speeds along designated paths, the robotic solution allows the detection abilities of a wide variety of sensors to be recorded and analyzed.

Article about the history of the Texas Fashion Collection held at the University of North Texas in Denton.

Although small wind turbine technology and economics have improved in recent years, the small wind market in the United States continues to be driven in large part by state incentives, such as cash rebates, favorable loan programs, and tax credits. This paper examines the state-by-state economic attractiveness of small residential wind systems. Economic attractiveness is evaluated primarily using the break-even turnkey cost (BTC) of a residential wind system as the figure of merit. The BTC is defined here as the aggregate installed cost of a small wind system that could be supported such that the system owner would break even (and receive a specified return on investment) over the life of the turbine, taking into account current available incentives, the wind resource, and the retail electricity rate offset by on-site generation. Based on the analysis presented in this paper, we conclude that: (1) the economics of residential, grid-connected small wind systems is highly variable by state and wind resource class, (2) significant cost reductions will be necessary to stimulate widespread market acceptance absent significant changes in the level of policy support, and (3) a number of policies could help stimulate the market, but state cash incentives currently have the most …

California's recently enacted Renewables Portfolio Standard (RPS, Senate Bill 1078) requires the state's investor-owned utilities (IOUs) to increase the renewable portion of their energy mix, with a goal of 20% renewable energy generation by 2017. Renewable generation projects will compete with each other to supply the IOUs, with the California Public Utilities Commission (CPUC) establishing a process to select the''least-cost, best-fit'' projects. The California Energy Commission (CEC), in support of the CPUC, organized a team to study integration costs in the context of RPS implementation. The analysis team, collectively referred to as the Methods Group, consists of researchers from the National Renewable Energy Laboratory and Oak Ridge National Laboratory and staff members from the California Independent System Operator, Dynamic Design Engineering, and the California Wind Energy Collaborative. This RPS Integration Study is motivated by the RPS's ''least-cost, best-fit'' bid selection criterion, which requires that indirect costs be considered in addition to the energy bid price when selecting eligible renewable projects. This paper summarizes the key results from the Phase I report. Specific issues examined in the report include capacity credit, regulation impacts and costs, and preliminary load-following impacts via the supplemental energy market in California. We also discuss the status …

This report describes the Characterization of Peeling-Ballooning Stability Limits on the Pedestal.

Physically interacting proteins or parts of proteins are expected to evolve in a coordinated manner that preserves proper interactions. Such coevolution at the amino acid-sequence level is well documented and has been used to predict interacting proteins, domains, and amino acids. Interacting proteins are also often precisely coexpressed with one another, presumably to maintain proper stoichiometry among interacting components. Here, we show that the expression levels of physically interacting proteins coevolve. We estimate average expression levels of genes from four closely related fungi of the genus Saccharomyces using the codon adaptation index and show that expression levels of interacting proteins exhibit coordinated changes in these different species. We find that this coevolution of expression is a more powerful predictor of physical interaction than is coevolution of amino acid sequence. These results demonstrate previously uncharacterized coevolution of gene expression, adding a different dimension to the study of the coevolution of interacting proteins and underscoring the importance of maintaining coexpression of interacting proteins over evolutionary time. Our results also suggest that expression coevolution can be used for computational prediction of protein protein interactions.

Atmospheric carbon dioxide (CO2) has increased dramatically since the beginning of the Industrial Revolution as a result of human activities (Keeling and others 1995, Houghton and others 2001). The primary cause of CO2 increases are worldwide fossil fuel burning, biomass burning, and cement manufacturing. These activities are, in turn, tied to the expanding world population and a rising demand for energy. If the steady increase of CO2 continues, there may be profound effects on the environment and the world economy from a "greenhouse effect" that has led to global warming of the atmosphere (Houghton and others 2001).

The study of complex flows by particle simulations is speeded up over molecular dynamics (MD) by more than two orders of magnitude by employing a stochastic collision dynamics method (DSMC) extended to high density (CBA). As a consequence, a picture generated on a single processor shows the typical features of the Rayleigh-Taylor instability and is in quantitative agreement with the experimentally found long time behavior.

This paper discusses the successes and failures over the past three years as efforts at the Idaho National Engineering and Environmental Laboratory (INEEL) have developed and evaluated robot behaviors that promote the emergence of swarm intelligence. Using a team of 12 small robots with the ability to respond to light and sound, the INEEL has investigated the fundamental advantages of swarm behavior as well as the limitations of this approach. The paper discusses the ways in which biology has inspired this work and the ways in which adherence to the biological model has proven to be both a benefit and hindrance to developing a fieldable system. The paper outlines how a hierarchical command and control structure can be imposed in order to permit human control at a level of group abstraction and discusses experimental results that show how group performance scales as different numbers of robots are utilized. Lastly, the paper outlines the applications for which the resulting capabilities have been applied and demonstrated.

A central feature of an Inertial Fusion Energy (IFE) power plant is a target that has been compressed and heated to fusion conditions by the energy input of the driver. The IFE target fabrication programs are focusing on methods that will scale to mass production, and working closely with target designers to make material selections that will satisfy a wide range of required and desirable characteristics. Targets produced for current inertial confinement fusion experiments are estimated to cost about $2500 each. Design studies of cost-effective power production from laser and heavy-ion driven IFE have found a cost requirement of about $0.25-0.30 each. While four orders of magnitude cost reduction may seem at first to be nearly impossible, there are many factors that suggest this is achievable. This paper summarizes the paradigm shifts in target fabrication methodologies that will be needed to economically supply targets and presents the results of ''nth-of-a-kind'' plant layouts and concepts for IFE power plant fueling. Our engineering studies estimate the cost of the target supply in a fusion economy, and show that costs are within the range of commercial feasibility for laser-driven and for heavy ion driven IFE.

Excimer laser fragmentation fluorescence spectroscopy (ELFFS) is used to monitor lead in soil sample and investigate laser-solid interactions. Pure lead nitrate salt and soil doped with lead nitrate are photolyzed with 193 nm light from an ArF excimer at fluences from 0.4 to 4 J/cm{sup 2}. Lead emission is observed at 357.2, 364.0, 368.3, 373.9 and 405.8 nm. Time-resolved data show the decay time of the lead emission at 405.8 nm grows with increasing fluence, and a plasma is formed above fluences of 2 J/cm{sup 2}, where a strong continuum emission interferes with the analyte signal. Fluences below this threshold allow us to achieve a detection limit of approximately 200 ppm in soil.

A series of titanium-substituted manganese oxides, Li{sub x}Ti{sub y}Mn{sub 1-y}O{sub 2} (y = 0.11, 0.22, 0.33, 0.44, and 0.55) with the Na{sub 0.44}MnO{sub 2} structure were prepared from Na{sub x}Ti{sub y}Mn{sub 1-y}O{sub 2} (x {approx} 0.44) precursors. The electrochemical characteristics of these compounds, which retain the unique double-tunnel structure during ion exchange, were examined in lithium/polymer electrolyte cells operating at 85 C. All of the substituted cathode materials intercalated lithium reversibly, with Li{sub x}Ti{sub 0.22}Mn{sub 0.78}O{sub 2} exhibiting the highest capacity in polymer cells, about 10-20% greater than that of unsubstituted Li{sub x}MnO{sub 2} made from Na{sub 0.44}MnO{sub 2}. In common with Li{sub x}MnO{sub 2}, the Ti-substituted materials exhibited good capacity retention over one hundred or more cycles, with some compositions exhibiting a fade rate of less than 0.03% per cycle.

Although DOE's Environmental Management program has made steady progress in cleaning up environmental legacies throughout the DOE complex, there are still significant remediation issues that remain to be solved. For example, DOE faces difficult challenges related to potential mobilization of radionuclides (e.g., actinides) and other hazardous contaminants in soils, removal and final treatment of high-level waste and residuals from leaking tanks, and the long-term stewardship of remediated sites and engineered disposal facilities, to name just a few. In some cases, new technologies and technology applications will be required based on current engineering expertise. In others, however, basic scientific research is needed to understand the mechanisms of how contaminants behave under specific conditions and how they interact with the environment, from which new engineering solutions can emerge. At Brookhaven National Laboratory (BNL) and Stony Brook University, scientists have teamed to use state-of-the-art synchrotron techniques to help understand the basic interactions of contaminants in the environment. Much of this work is conducted at the BNL National Synchrotron Light Source (NSLS), which is a user facility that provides high energy X-ray and ultraviolet photon beams to facilitate the examination of contaminants and materials at the molecular level. These studies allow us to determine …

The objective of the Department of Energy's (DOE) Fernald Closure Project (FCP), in suburban Cincinnati, Ohio, is to safely complete the environmental restoration of the Fernald site by 2006. Over 200 out of 220 total structures, at this DOE plant site which processed uranium ore concentrates into high-purity uranium metal products, have been safely demolished, including eight of the nine major production plants. Documented Safety Analyses (DSAs) for these facilities have gone through a process of simplification, from individual operating Safety Analysis Reports (SARs) to a single site-wide Authorization Basis containing nuclear facility Bases for Interim Operations (BIOs) to individual project Auditable Safety Records (ASRs). The final stage in DSA simplification consists of project-specific Integrated Health and Safety Plans (I-HASPs) and Nuclear Health and Safety Plans (N-HASPs) that address all aspects of safety, from the worker in the field to the safety basis requirements preserving the facility/activity hazard categorization. This paper addresses the evolution of Safety Basis Documentation (SBD), as DSAs, from production through site closure.

Recently the collider physics community has seen significant advances in the formalisms and implementations of event generators. This review is a primer of the methods commonly used for the simulation of high energy physics events at particle colliders. We provide brief descriptions, references, and links to the specific computer codes which implement the methods. The aim is to provide an overview of the available tools, allowing the reader to ascertain which tool is best for a particular application, but also making clear the limitations of each tool.

Average methylmercury levels in five Savannah River tributary streams sampled 11 times over two years were nearly twice as high as in the Savannah River. Total mercury levels in the tributaries did not differ significantly from the river. All of the tributaries drained extensive wetlands that would be expected to support comparatively high rates of methylation. Mercury concentrations in Asiatic clams (Corbicula fluminea) collected from the discharge plumes of Savannah River tributaries were significantly higher than in Asiatic clams collected from the Savannah River upstream from the tributary mouths . These results indicate that streams draining wetlands into coastal plain rivers can create localized areas of elevated methylmercury with resulting increases in the mercury levels of river biota.

Plans to expand the western grid are now underway. Bringing power from low-cost remote resources--including wind--to load centers could reduce costs for all consumers. But many paths appear to be already congested. Locational marginal price-based modeling is designed to identify the most cost-effective paths to be upgraded. The ranking of such paths is intended as the start of a process of political and regulatory approvals that are expected to result in the eventual construction of new and upgraded lines. This paper reviews the necessary data and analytical tasks to accurately represent wind in such modeling, and addresses some policy and regulatory issues that can help with wind integration into the grid. Providing wind fair access to the grid also (and more immediately) depends on tariff and regulatory changes. Expansion of the Rocky Mountain Area Transmission Study (RMATS) study scope to address operational issues supports the development of transmission solutions that enable wind to connect and deliver power in the next few years--much sooner than upgrades can be completed.

This article investigates the impact of the political information available on-line on college students’ motivation to vote. The results illustrate that not only politicians, but educators should be cognizant of this civic engagement process. Schools and teachers of all levels are one the front lines of the battle to create a more informed, more involved citizenry; higher education has a strong influence on motivation to vote.

The effective oxygen conductivities in the zirconia networks of porous LSM-YSZ and LSM-SYSZ composites [i.e. La0.85Sr0.15MnO3(Y2O3)0.08(ZrO2)0.92 and La0.85Sr0.15MnO3(c2O3)0.1(Y2O3)0.01(ZrO2)0.89,respectively] were evaluated by an AC impedance technique using specimens in which LSM was removed by hydrochloric acid leaching. The oxygen conductivities of porous YSZ and SYSZ alone followed a Koh-Fortini relationship. LSM-containing zirconia network conductivities were additionally decreased by the presence of the LSM, presumably by increased grain boundary resistances. Constriction resistances were estimated to have a minor effect.

The U.S. Department of Energy/National Renewable Energy Laboratory (DOE/NREL) has developed a spreadsheet-based wind model (Jobs and Economic Development Impact (JEDI)) that incorporates economic multipliers for jobs, income, and output. Originally developed with state-specific parameters, it can also be used to conduct county and regional analyses. NREL has enlisted the Wind Powering America (WPA) State Wind Working Groups (SWWGs) to conduct county-specific economic impact analyses and has encouraged them to use JEDI if they do not have their own economic model. The objective of the analyses is to identify counties within WPA target states, and preferably counties with a significant agricultural sector, that could economically benefit from wind development. These counties could then explore opportunities to tap into the United States Department of Agriculture (USDA) Farm Bill Section 9006 grants and loans to stimulate wind development. This paper describes the JEDI model and how i t can be used. We will also summarize a series of analyses that were completed to fulfill a General Accounting Office (GAO) request to provide estimates of the economic development benefits of wind power.

The goal of this investigation was to assess the accuracy of 18F-fluorodihydrorotenone (18F-FDHR) as a new deposited myocardial flow tracer and compare the results to those for 201Tl. Methods. The kinetics of these flow tracers were evaluated in 22 isolated, erythrocyte- and albumin-perfused rabbit hearts over a flow range encountered in patients. The two flow tracers plus a vascular reference tracer (131I-albumin) were introduced as a bolus through a port just above the aortic cannula. Myocardial extraction, retention, washout, and uptake parameters were computed from the venous outflow curves using the multiple indicator dilution technique and spectral analysis. Results. The mean initial extraction fractions of 18F-FDHR (0.85 +- 0.07) and 201Tl (0.87 +- 0.05) were not significantly different, although the initial extraction fraction for 18F-FDHR declined with flow (P < 0.0001), whereas the initial extraction fraction of 201Tl did not. Washout of 201Tl was faster (P < 0.001) and more affected by flow (P < 0.05) than 18F-FDHR washout. Except for initial extraction fraction, 18F-FDHR retention was greater (P < 0.001) and less affected by flow (P < 0.05) than 201Tl retention. Reflecting its superior retention, net uptake of 18F-FDHR was better correlated with flow than 201Tl uptake at both …

This paper provides a preliminary assessment of two possible versions of the Next Generation Nuclear Plant (NGNP), a prismatic fuel type helium gas-cooled reactor and a pebblebed fuel helium gas reactor. Both designs will meet the three basic requirements that have been set for the NGNP: a coolant outlet temperature of 1000 C, passive safety, and a total power output consistent with that expected for commercial high-temperature gas-cooled reactors.

Determining reaction cross sections on short-lived nuclear species is a major challenge for nuclear physics and nuclear astrophysics. Many of these nuclei are too difficult to produce with currently available experimental techniques or too short-lived to serve as targets in present-day set-ups. Some nuclear reactions will remain immeasurable even at upcoming and planned radioactive beam facilities. It is therefore important to explore alternative methods for determining reaction cross sections on unstable nuclei.