9,847 research outputs found

    Digital filter suppresses effects of nonstatistical noise bursts on multichannel scaler digital averaging systems

    Get PDF
    Digital filter suppresses the effects of nonstatistical noise bursts on data averaged over multichannel scaler. Interposed between the sampled channels and the digital averaging system, it uses binary logic circuitry to compare the number of counts per channel with the average number of counts per channel

    Non-linear screening of external charge by doped graphene

    Get PDF
    We solve a nonlinear integral equation for the electrostatic potential in doped graphene due to an external charge, arising from a Thomas-Fermi (TF) model for screening by graphene's π\pi electron bands. In particular, we study the effects of a finite equilibrium charge carrier density in graphene, non-zero temperature, non-zero gap between graphene and a dielectric substrate, as well as the nonlinearity in the band density of states. Effects of the exchange and correlation interactions are also briefly discussed for undoped graphene at zero temperature. Nonlinear results are compared with both the linearized TF model and the dielectric screening model within random phase approximation (RPA). In addition, image potential of the external charge is evaluated from the solution of the nonlinear integral equation and compared to the results of linear models. We have found generally good agreement between the results of the nonlinear TF model and the RPA model in doped graphene, apart from Friedel oscillations in the latter model. However, relatively strong nonlinear effects are found in the TF model to persist even at high doping densities and large distances of the external charge.Comment: 12 pages including 6 figure

    Cubic spline prewavelets on the four-directional mesh

    Get PDF
    In this paper, we design differentiable, two dimensional, piecewise polynomial cubic prewavelets of particularly small compact support. They are given in closed form, and provide stable, orthogonal decompositions of L^2(\RR^2). In particular, the splines we use in our prewavelet constructions give rise to stable bases of spline spaces that contain all cubic polynomials, whereas the more familiar box spline constructions cannot reproduce all cubic polynomials, unless resorting to a box spline of higher polynomial degree

    C2 piecewise cubic quasi-interpolants on a 6-direction mesh

    Get PDF
    We study two kinds of quasi-interpolants (abbr. QI) in the space of C2 piecewise cubics in the plane, or in a rectangular domain, endowed with the highly symmetric triangulation generated by a uniform 6-direction mesh. It has been proved recently that this space is generated by the integer translates of two multi-box splines. One kind of QIs is of differential type and the other of discrete type. As those QIs are exact on the space of cubic polynomials, their approximation order is 4 for sufficiently smooth functions. In addition, they exhibit nice superconvergent properties at some specific points. Moreover, the infinite norms of the discrete QIs being small, they give excellent approximations of a smooth function and of its first order partial derivatives. The approximation properties of the QIs are illustrated by numerical examples

    The Health Care Financing Maze for Working-Age People with Disabilities

    Get PDF
    Much of the research on health care financing for people with disabilities has focused on the Medicaid and Medicare programs. The findings of this research often highlight the inadequacies of those programs in providing appropriate services to address the special needs of people with disabilities. A focus on these large programs, however, obscures the role of other public and private insurers, as well as the role of programs that provide many additional services to this population – all of which add complexity to the system. The purpose of this paper is to describe the health care financing system as a whole, including the large public programs, other public and private insurers, and the many other programs that provide additional services. The description of the system highlights structural problems that need to be addressed in order to substantially improve the delivery of health and related services to people with disabilities. In the next section, we describe each source of health care financing for working-age people with disabilities and highlight its implications for service delivery and quality of life. In the concluding section, we describe the key structural shortcomings of the current financing system, assess the extent to which current reform efforts are addressing these shortcomings, and discuss the implications for broader efforts to reform health care financing system

    Reconnection in Marginally Collisionless Accretion Disk Coronae

    Full text link
    We point out that a conventional construction placed upon observations of accreting black holes, in which their nonthermal X-ray spectra are produced by inverse comptonization in a coronal plasma, suggests that the plasma is marginally collisionless. Recent developments in plasma physics indicate that fast reconnection takes place only in collisionless plasmas. As has recently been suggested for the Sun's corona, such marginal states may result from a combination of energy balance and the requirements of fast magnetic reconnection.Comment: Revised in response to referee. Accepted ApJ. 11 pp., no figures. Uses aastex 5.0

    A three-dimensional hard spheres theory of scattering of gas atoms from a solid surface

    Get PDF
    Three dimensional model of monatomic gases interacting with solid surfaces represented by similar, noninteracting hard sphere

    The Evolution of Cuspy Triaxial Galaxies Harboring Central Black Holes

    Full text link
    We use numerical simulations to study the evolution of triaxial elliptical galaxies with central black holes. In contrast to earlier numerical studies which used galaxy models with central density ``cores,'' our galaxies have steep central cusps, like those observed in real ellipticals. As a black hole grows in these cuspy triaxial galaxies, the inner regions become rounder owing to chaos induced in the orbit families which populate the model. At larger radii, however, the models maintain their triaxiality, and orbital analyses show that centrophilic orbits there resist stochasticity over many dynamical times. While black hole induced evolution is strong in the inner regions of these galaxies, and reaches out beyond the nominal ``sphere of influence'' of a black hole, our simulations do not show evidence for a rapid {\it global} transformation of the host. The triaxiality of observed elliptical galaxies is therefore not inconsistent with the presence of supermassive black holes at their centers.Comment: 15 pages, 7 figures (1 color). Accepted for publication in Ap

    ANALYSIS OF SUBGROUP EFFECTS IN RANDOMIZED TRIALS WHEN SUBGROUP MEMBERSHIP IS INFORMATIVELY MISSING: APPLICATION TO THE MADIT II STUDY

    Get PDF
    In this paper, we develop and implement a general sensitivity analysis methodology for drawing inference about subgroup effects in a two-arm randomized trial when subgroup status is only known for a non-random sample in one of the trial arms. The methodology is developed in the context of the MADIT II study, a randomized trial designed to evaluate the effectiveness of implantable defibrillators on survival

    Understanding Contextual Differences in Residential LTC Provision for Cross-National Research : Identifying Internationally Relevant CDEs

    Get PDF
    Long-term care (LTC) reflects a growing emphasis on person-centered care (PCC), with services oriented around individuals' needs and preferences. Addressing contextual and cultural differences across countries offers important insight into factors that facilitate or hinder application of PCC practices within and across countries. This article takes an international lens to consider country-specific contexts of LTC, describing preliminary steps to develop common data elements that capture contextual differences across LTC settings globally. Through an iterative series of online, telephone, and in-person sessions, we engaged in in-depth discussions with 11 colleague experts in residential LTC and coauthors from six countries (China and Hong Kong, England, Sweden, Thailand, Trinidad and Tobago, and the United States). Our discussions yielded rich narrative describing a vast range in types of LTC settings, leading to our development of a working definition of residential LTC. Scope of services, funding, ownership, and regulations varied greatly across countries and across different residential LTC settings within countries. Moving forward, we recommend expanding our activities to countries that reflect different stages of residential LTC development. Our goal is to contribute to a larger initiative underway by the WE-THRIVE consortium to establish a global research measurement infrastructure that advances PCC internationally.Peer reviewe
    corecore