156 research outputs found
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Architectural requirements for the Red Storm computing system.
This report is based on the Statement of Work (SOW) describing the various requirements for delivering 3 new supercomputer system to Sandia National Laboratories (Sandia) as part of the Department of Energy's (DOE) Accelerated Strategic Computing Initiative (ASCI) program. This system is named Red Storm and will be a distributed memory, massively parallel processor (MPP) machine built primarily out of commodity parts. The requirements presented here distill extensive architectural and design experience accumulated over a decade and a half of research, development and production operation of similar machines at Sandia. Red Storm will have an unusually high bandwidth, low latency interconnect, specially designed hardware and software reliability features, a light weight kernel compute node operating system and the ability to rapidly switch major sections of the machine between classified and unclassified computing environments. Particular attention has been paid to architectural balance in the design of Red Storm, and it is therefore expected to achieve an atypically high fraction of its peak speed of 41 TeraOPS on real scientific computing applications. In addition, Red Storm is designed to be upgradeable to many times this initial peak capability while still retaining appropriate balance in key design dimensions. Installation of the Red Storm computer system at Sandia's New Mexico site is planned for 2004, and it is expected that the system will be operated for a minimum of five years following installation
Understanding Farmersâ Forecast Use from Their Beliefs, Values, Social Norms, and Perceived Obstacles
Although the accuracy of weather and climate forecasts is continuously improving and new information retrieved from climate data is adding to the understanding of climate variation, use of the forecasts and climate information by farmers in farming decisions has changed little. This lack of change may result from knowledge barriers and psychological, social, and economic factors that undermine farmer motivation to use forecasts and climate information. According to the theory of planned behavior (TPB), the motivation to use forecasts may arise from personal attitudes, social norms, and perceived control or ability to use forecasts in specific decisions. These attributes are examined using data from a survey designed around the TPB and conducted among farming communities in the region of eastern Nebraska and the western U.S. Corn Belt. There were three major findings: 1) the utility and value of the forecasts for farming decisions as perceived by farmers are, on average, around 3.0 on a 0â7 scale, indicating much room to improve attitudes toward the forecast value. 2) The use of forecasts by farmers to influence decisions is likely affected by several social groups that can provide âexpert viewpointsâ on forecast use. 3) A major obstacle, next to forecast accuracy, is the perceived identity and reliability of the forecast makers. Given the rapidly increasing number of forecasts in this growing service business, the ambiguous identity of forecast providers may have left farmers confused and may have prevented them from developing both trust in forecasts and skills to use them. These findings shed light on productive avenues for increasing the influence of forecasts, which may lead to greater farming productivity. In addition, this study establishes a set of reference points that can be used for comparisons with future studies to quantify changes in forecast use and influence
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Effects of numerical methods on comparisons between experiments and simulations of shock-accelerated mixing.
We consider the detailed structures of mixing flows for Richtmyer-Meshkov experiments of Prestridge et al. [PRE 00] and Tomkins et al. [TOM 01] and examine the most recent measurements from the experimental apparatus. Numerical simulations of these experiments are performed with three different versions of high resolution finite volume Godunov methods. We compare experimental data with simulations for configurations of one and two diffuse cylinders of SF{sub 6} in air using integral measures as well as fractal analysis and continuous wavelet transforms. The details of the initial conditions have a significant effect on the computed results, especially in the case of the double cylinder. Additionally, these comparisons reveal sensitive dependence of the computed solution on the numerical method
Serotonin-3 Receptors in the Posterior Ventral Tegmental Area Regulate Ethanol Self-Administration of Alcohol-Preferring (P) Rats
Several studies indicated the involvement of serotonin-3 (5-HT
3
) receptors in regulating alcohol-
drinking behavior. The objective of this study was to determine the involvement of 5-HT
3
receptors within the ventral tegmental area (VTA) in regulating ethanol self-administration by
alcohol-preferring (P) rats. Standard two-lever operant chambers were used to examine the effects
of 7 consecutive bilateral micro-infusions of ICS205-930 (ICS), a 5-HT
3
receptor antagonist,
directly into the posterior VTA on the acquisition and maintenance of 15% (v/v) ethanol self-
administration. P rats readily acquired ethanol self-administration by the 4
th
session. The three
highest doses (0.125, 0.25 and 1.25 ug) of ICS prevented acquisition of ethanol self-
administration. During the acquisition post-injection period, all rats treated with ICS demonstrated
higher responding on the ethanol lever, with the highest dose producing the greatest effect. In
contrast, during the maintenance phase, the 3 highest doses (0.75, 1.0 and 1.25 ug) of ICS
significantly increased responding on the ethanol lever; following the 7-day dosing regimen,
responding on the ethanol lever returned to control levels. Micro-infusion of ICS into the posterior
VTA did not alter the low responding on the water lever, and did not alter saccharin (0.0125%
w/v) self-administration.. Micro-infusion of ICS into the anterior VTA did not alter ethanol self-
administration. Overall, the results of this study suggest that 5-HT
3
receptors in the posterior VTA
of the P rat may be involved in regulating ethanol self-administration. In addition, chronic operant
ethanol self-administration, and/or repeated treatments with a 5-HT
3
receptor antagonist may alter
neuronal circuitry within the posterior VTA
Genomewide Association Studies of LRRK2 Modifiers of Parkinson's Disease.
OBJECTIVE: The aim of this study was to search for genes/variants that modify the effect of LRRK2 mutations in terms of penetrance and age-at-onset of Parkinson's disease. METHODS: We performed the first genomewide association study of penetrance and age-at-onset of Parkinson's disease in LRRK2 mutation carriers (776 cases and 1,103 non-cases at their last evaluation). Cox proportional hazard models and linear mixed models were used to identify modifiers of penetrance and age-at-onset of LRRK2 mutations, respectively. We also investigated whether a polygenic risk score derived from a published genomewide association study of Parkinson's disease was able to explain variability in penetrance and age-at-onset in LRRK2 mutation carriers. RESULTS: A variant located in the intronic region of CORO1C on chromosome 12 (rs77395454; p value = 2.5E-08, beta = 1.27, SE = 0.23, risk allele: C) met genomewide significance for the penetrance model. Co-immunoprecipitation analyses of LRRK2 and CORO1C supported an interaction between these 2 proteins. A region on chromosome 3, within a previously reported linkage peak for Parkinson's disease susceptibility, showed suggestive associations in both models (penetrance top variant: p value = 1.1E-07; age-at-onset top variant: p value = 9.3E-07). A polygenic risk score derived from publicly available Parkinson's disease summary statistics was a significant predictor of penetrance, but not of age-at-onset. INTERPRETATION: This study suggests that variants within or near CORO1C may modify the penetrance of LRRK2 mutations. In addition, common Parkinson's disease associated variants collectively increase the penetrance of LRRK2 mutations. ANN NEUROL 2021;90:82-94
Sugarcane (Saccharum X officinarum): A Reference Study for the Regulation of Genetically Modified Cultivars in Brazil
Global interest in sugarcane has increased significantly in recent years due to its economic impact on sustainable energy production. Sugarcane breeding and better agronomic practices have contributed to a huge increase in sugarcane yield in the last 30Â years. Additional increases in sugarcane yield are expected to result from the use of biotechnology tools in the near future. Genetically modified (GM) sugarcane that incorporates genes to increase resistance to biotic and abiotic stresses could play a major role in achieving this goal. However, to bring GM sugarcane to the market, it is necessary to follow a regulatory process that will evaluate the environmental and health impacts of this crop. The regulatory review process is usually accomplished through a comparison of the biology and composition of the GM cultivar and a non-GM counterpart. This review intends to provide information on non-GM sugarcane biology, genetics, breeding, agronomic management, processing, products and byproducts, as well as the current technologies used to develop GM sugarcane, with the aim of assisting regulators in the decision-making process regarding the commercial release of GM sugarcane cultivars
Predicting Academic Performance: A Systematic Literature Review
The ability to predict student performance in a course or program creates opportunities to improve educational outcomes. With effective performance prediction approaches, instructors can allocate resources and instruction more accurately. Research in this area seeks to identify features that can be used to make predictions, to identify algorithms that can improve predictions, and to quantify aspects of student performance. Moreover, research in predicting student performance seeks to determine interrelated features and to identify the underlying reasons why certain features work better than others. This working group report presents a systematic literature review of work in the area of predicting student performance. Our analysis shows a clearly increasing amount of research in this area, as well as an increasing variety of techniques used. At the same time, the review uncovered a number of issues with research quality that drives a need for the community to provide more detailed reporting of methods and results and to increase efforts to validate and replicate work.Peer reviewe
Localization Subsystem Simulation for Mobile Robot
Tato prĂĄce ĆeĆĄĂ implementaci lokalizaÄnĂho algoritmu pro lokalizaÄnĂ subsystĂ©m mobilnĂho robotu. VĂœstupem prĂĄce je simulaÄnĂ program v jazyce C\#, kterĂœ simuluje chovĂĄnĂ senzorĆŻ, pohyb a lokalizaÄnĂ algoritmus zaloĆŸenĂœ na pravdÄpodobnosti. KonkrĂ©tnÄ se jednĂĄ o algoritmus Monte Carlo. SimulaÄnĂ software obsahuje moĆŸnost vĂœbÄru mapy, grafickĂ© zobrazenĂ prĆŻbÄhu simulace, krokovĂĄnĂ lokalizaÄnĂho algoritmu Monte Carlo, LiDAR pro mÄĆenĂ vzdĂĄlenosti, nastavenĂ ĆĄumu a nastavenĂ hustoty ÄĂĄstic pro MCL.The thesis deals with an implementation of a localization algorithm for a localization subsystem of a mobile robot. The outcome is a simulation program in C\# language which simulates sensor behaviour, motion and localization algorithm based on probability. Specifically, it is Monte Carlo algorithm. The simulation software contains a possibility to choose a map, graphic projection of a simulation development, debuging of the Monte Carlo localization algorithm, LiDAR for distance measuring, noise level setting and density of particles for MCL setting.450 - Katedra kybernetiky a biomedicĂnskĂ©ho inĆŸenĂœrstvĂvĂœborn
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