357 research outputs found

    On the numerical solution of chaotic dynamical systems using extend precision floating point arithmetic and very high order numerical methods

    Get PDF
    Multiple results in the literature exist that indicate that all computed solutions to chaotic dynamical systems are time-step dependent. That is, solutions with small but different time steps will decouple from each other after a certain (small) finite amount of simulation time. When using double precision floating point arithmetic time step independent solutions have been impossible to compute, no matter how accurate the numerical method. Taking the well-known Lorenz equations as an example, we examine the numerical solution of chaotic dynamical systems using very high order methods as well as extended precision floating point number systems. Time step independent solutions are obtained over a finite period of time. However even with a sixteenth order numerical method and with quad-double floating point numbers, there is a limit to this approach

    Does Broad Banding Improve Pay System Effectiveness?

    Get PDF
    Edwin W. Arnold, Ph.D., SPHR, is professor of management, Department of Management, Auburn University Montgomery, Montgomery, AL 36124. Clyde J. Scott, Ph.D., is associate professor of management, Department of Management and Marketing, University of Alabama, Tuscaloosa, AL 35487

    Bayesian model search and multilevel inference for SNP association studies

    Full text link
    Technological advances in genotyping have given rise to hypothesis-based association studies of increasing scope. As a result, the scientific hypotheses addressed by these studies have become more complex and more difficult to address using existing analytic methodologies. Obstacles to analysis include inference in the face of multiple comparisons, complications arising from correlations among the SNPs (single nucleotide polymorphisms), choice of their genetic parametrization and missing data. In this paper we present an efficient Bayesian model search strategy that searches over the space of genetic markers and their genetic parametrization. The resulting method for Multilevel Inference of SNP Associations, MISA, allows computation of multilevel posterior probabilities and Bayes factors at the global, gene and SNP level, with the prior distribution on SNP inclusion in the model providing an intrinsic multiplicity correction. We use simulated data sets to characterize MISA's statistical power, and show that MISA has higher power to detect association than standard procedures. Using data from the North Carolina Ovarian Cancer Study (NCOCS), MISA identifies variants that were not identified by standard methods and have been externally ``validated'' in independent studies. We examine sensitivity of the NCOCS results to prior choice and method for imputing missing data. MISA is available in an R package on CRAN.Comment: Published in at http://dx.doi.org/10.1214/09-AOAS322 the Annals of Applied Statistics (http://www.imstat.org/aoas/) by the Institute of Mathematical Statistics (http://www.imstat.org

    Studies Related to Nutrients Entering Groundwater From the Heber Valley Sewer Farm and Dairies

    Get PDF
    Foreword: This report includes the results from a two year study in the Heber Valley to determine amounts of nutrients that are entering the groundwaters of the Heber Valley, and might ultimately enter Deer Creek Reservoir. Since Deer Creek Reservoir in Heber Valley, Utah supplies approximately 65 percent of the water distributed to Salt Lake County, the maintenance of its quality is of considerable importance. To maintain the quality of this reservoir and limit its eutrophication best management practices for surface water have been implemented gradually during the past decade in Heber Valley. These practices have significantly improved the qualities of surface streams flowing into the reservoir. However, data for amounts of phosphorus and nitrogen in groundwater inflows to the reservoir are several times larger than predicted from 1967 data. Concern has been voiced that perhaps cleaning up the surface inflows by spreading treated sewage on land, retaining dairy wastes in lagoon, etc, have only delayed the arrival time of nutrients into Deer Creek Reservoir, and that their transmission through gruondwaters into the reservoir will result in eutrophication unless other measures are implemented. To provide data for better understanding of the processes assocaited with soil sorption and transmission of chemicals (with a focus on phosphorus and nitrogen) into the saturated groundwater and ultimately into Deer Creek Reservoir, a three pronged research program was initiated by Utah State University during the Spring of 1989. This program consisted of: 1. Installation of unsaturated zone (Vandose zone) samples that extract water from the partially saturated soil at 6 sites (with two samplers at different depths at each site) within the land disposal area of the Heber Valley Special Service District (referred to as the sewer farm hereafter), and adjacent to two liquid manure lagoons at dairy farms. 2. Laboratory sorption studies on soil columns that were acquired in an undistrubed state from the 6 sites in the above sewer farm , and 3. Development of computer solutions to estimate the transmission of nutrients through the unsaturated top soil into the groundwater. An earlier 1990 preliminary report Interim Report for Studies related to Nutrients Entering Groundwater from the Heber Valley Sewer Farm and Dairies provided information related to the results of the laboratory sorption studies, and tentative results from the field studies based on the data collected during the summer of 1989. Since the field data given in the earlier report covered only a portion of ayear, and the study was continued for a second year that report is superceded by this report. This report provides the data collected over the two year period of the study, 1989-1990. Included in this report are field data obtained from the most critical spring period of 1990 when the surface soils recieve the relatively large quantities of snow melt water. The 1990 water year was again a dry year in which precipitation was considerably below normal. Thus the field collection period did not include a truly wet condition as will undoubtedly occur during years of above normal precipitation. Above normal rainfall did occur during the months of April and May, 1991. However this was not anticipated and the field samplers were unfortunately removed prior to these occurences to allow more easy working of the farm area. Since only a few copies of the above mentioned interim report were reproduced, this report duplicates the description of the field instrumentation, and the laboratory sorption studies. The data tables contained in that report have been updated to include field data from the second year through 1990. The results from the computer solutions that were contained in the interim report as Appendix A are not included herein, however. That report must be consulted for this detail. Field data collected from the first year indicated that larger quantities of nitrogen in the form of nitrate (NO3) than phophorus were within the unsaturated surface soils of the farm irrigated by the treated sewage, and by the dairy lagoons. Based on this information an additional research program, or changing the emphasis of the research, was directed to studying the nitrogen cycle in the groundwater system of Heber Valley to determine in natural processes reduce the amount of NO3- reaching Deer Creek Reservoir through the Heber Valley aquifers. More specifically the additional emphasis was deirected to determine whether conditions exist that favor denitrification and the extent by which such process might be reducing the amounts of NO3- input to Deer Creek Reservoir from the irrigated farm of the Heber Valley Special Service District, and two dairy lagoons. Denitrification is a process whereby bacteria transfer electrons from compounds, known as electron donors, to NO3-, an electron acceptor. The end products of this reduction are gases of N2O and N2, both of which escape to the atmosphere and thus reduce the amount of nitrogen in the water. The results of this sadditional research will be reported in a forthcoming project report consisting of the Ph.D. dissertation by Scott F. Korom Denitrification in the Unconsolidated Deposits of the Heber Valley Aquifer. This dissertation is being written in the format now allowed by Utah State University where different sections are designed as separate papers for submission to professional journals. Therefore the results of the denitrification phases of the research should also be available in future professional journal papers

    A Conceptual Model for a Universal Severity of Emergency Report (USER): An Example in Aviation

    Get PDF
    In emergency situations, it is important that information be communicated quickly, concisely, and efficiently. Breakdowns can occur when the receiver of the emergency call does not fully understand the information that the person is sending. The purpose of this paper is to present a new model for enhancing communication between the sender and receiver in emergency situations. The Universal Severity of Emergency Report (USER) is a model designed to be used in emergency situations and convey more information about the current state of the person declaring the emergency than is currently offered by emergency communication channels. USER provides three key pieces of vital information: severity of the situation, capabilities of the sender, and ability to communicate. Severity identifies the level of the emergency on a scale of 1, 2, or 3. Capabilities use the colors white, yellow, and red to indicate the current self-determined capabilities of the individual. Communicate notifies the receiver if the individual is able to communicate or is unable to communicate. This paper presents this concept in an aviation context, but USER has the potential to be used in any number of industries, including medical, military, shipping, transportation, space flight, and law enforcement

    Low-Melt Poly(amic Acids) and Polyimides and Their Uses

    Get PDF
    Provided are low-melt polyimides and poly(amic acids) (PAAs) for use in repair of electrical wire insulation, flat or ribbon wire harnesses, and flat surfaces comprised of high-performance polymers such as inflatables or solar panels applications. Also provided are methods and devices for repair of electrical insulation

    Low-Melt Poly(Amic Acids) and Polyimides and Their Uses

    Get PDF
    Provided are low-melt polyimides and poly(amic acids) (PAAs) for use as adhesives, and methods of using the materials for attaching two substrates. The methods typically form an adhesive bond that is hermetically sealed to both substrates. Additionally, the method typically forms a cross-linked bonding material that is flexible

    Low-Melt Poly(Amic Acids) and Polyimides and Their Uses

    Get PDF
    Provided are low-melt polyimides and poly(amic acids) (PAAs) for use in repair of electrical wire insulation, flat or ribbon wire harnesses, and flat surfaces comprised of high-performance polymers such as inflatables or solar panels applications. Also provided are methods and devices for repair of electrical insulation

    Methods and tools for Bayesian variable selection and model averaging in normal linear regression

    Get PDF
    In this paper, we briefly review the main methodological aspects concerned with the application of the Bayesian approach to model choice and model averaging in the context of variable selection in regression models. This includes prior elicitation, summaries of the posterior distribution and computational strategies. We then examine and compare various publicly available R-packages, summarizing and explaining the differences between packages and giving recommendations for applied users. We find that all packages reviewed (can) lead to very similar results, but there are potentially important differences in flexibility and efficiency of the packages

    New paradigm for macromolecular crystallography experiments at SSRL: automated crystal screening and remote data collection

    Get PDF
    Through the combination of robust mechanized experimental hardware and a flexible control system with an intuitive user interface, SSRL researchers have screened over 200 000 biological crystals for diffraction quality in an automated fashion. Three quarters of SSRL researchers are using these data-collection tools from remote locations
    • …
    corecore