4,079 research outputs found

    A new representation for non--local operators and path integrals

    Full text link
    We derive an alternative representation for the relativistic non--local kinetic energy operator and we apply it to solve the relativistic Salpeter equation using the variational sinc collocation method. Our representation is analytical and does not depend on an expansion in terms of local operators. We have used the relativistic harmonic oscillator problem to test our formula and we have found that arbitrarily precise results are obtained, simply increasing the number of grid points. More difficult problems have also been considered, observing in all cases the convergence of the numerical results. Using these results we have also derived a new representation for the quantum mechanical Green's function and for the corresponding path integral. We have tested this representation for a free particle in a box, recovering the exact result after taking the proper limits, and we have also found that the application of the Feynman--Kac formula to our Green's function yields the correct ground state energy. Our path integral representation allows to treat hamiltonians containing non--local operators and it could provide to the community a new tool to deal with such class of problems.Comment: 9 pages ; 1 figure ; refs added ; title modifie

    Bigger Yields From Everbearing Strawberries

    Get PDF
    Many home gardeners and commercial producers of strawberries in Iowa have had discouraging results with everbearing strawberries. One reason is the hot, dry weather we usually have during July and August. Because moisture is short, the late summer crop often consists mostly of small fruits or nubbins - sometimes not even worth harvesting

    Calculating expected DNA remnants from ancient founding events in human population genetics

    Get PDF
    <p>Abstract</p> <p>Background</p> <p>Recent advancements in sequencing and computational technologies have led to rapid generation and analysis of high quality genetic data. Such genetic data have achieved wide acceptance in studies of historic human population origins and admixture. However, in studies relating to small, recent admixture events, genetic factors such as historic population sizes, genetic drift, and mutation can have pronounced effects on data reliability and utility. To address these issues we conducted genetic simulations targeting influential genetic parameters in admixed populations.</p> <p>Results</p> <p>We performed a series of simulations, adjusting variable values to assess the affect of these genetic parameters on current human population studies and what these studies infer about past population structure. Final mean allele frequencies varied from 0.0005 to over 0.50, depending on the parameters.</p> <p>Conclusion</p> <p>The results of the simulations illustrate that, while genetic data may be sensitive and powerful in large genetic studies, caution must be used when applying genetic information to small, recent admixture events. For some parameter sets, genetic data will not be adequate to detect historic admixture. In such cases, studies should consider anthropologic, archeological, and linguistic data where possible.</p

    On the Path Integral in Imaginary Lobachevsky Space

    Full text link
    The path integral on the single-sheeted hyperboloid, i.e.\ in DD-dimensional imaginary Lobachevsky space, is evaluated. A potential problem which we call ``Kepler-problem'', and the case of a constant magnetic field are also discussed.Comment: 16 pages, LATEX, DESY 93-14

    A UAV Mission Hierarchy

    Get PDF
    In the following sections, each of the primary missions are decomposed into mission planning, management, and replanning segments in order to identify what the primary functions a human operator will need to perform. The goal is to understand what tasks/functions are common across different UAV missions and platforms in order to map the generalizability of any particular research project.Prepared for Charles River Analytic

    Weaning Weight Summary for South Dakota Livestock Production Records Association Member Herds Using Crossbreeding

    Get PDF
    The primary objective of this study was to provide members of the Production Records Association an analysis of the weaning weights of various crossbreds produced in member herds. The results should form an important part of the total information needed by members and other cattlemen to formulate individual breeding programs
    corecore