1,385 research outputs found

    Lifetime vigorous but not light-to-moderate habitual physical activity impacts favorably on carotid stiffness in young adults the Amsterdam growth and health longitudinal study

    Get PDF
    Higher levels of habitual physical activity favorably impact on arterial stiffness. It is not clear, however, whether lifetime habitual physical activities of different intensities carry the same protective effect and to what extent any such effect is mediated by other biological cardiovascular risk factors. We, therefore, examined longitudinal data on habitual physical activity and cardiovascular risk factors (8 repeated measures between the ages of 13 and 36 years) in 373 subjects in whom stiffness estimates of the carotid artery were assessed at age 36 years using noninvasive ultrasonography. The time spent in habitual physical activities (in minutes per week) throughout the longitudinal period was compared between subjects across tertiles of the following stiffness estimates: ÎČ-stiffness index, distensibility and compliance coefficients, and the Young's elastic modulus. After adjustments for sex, body height, and other lifestyle variables, subjects in the highest tertile of the ÎČ-stiffness index (ie, with stiffer arteries) had spent, on average, throughout the longitudinal period, less time in vigorous (-26.5 [95% CI:-45.9 to-7.1]) but less so in light-to-moderate habitual physical activities (-11.2 [95% CI:-53.5 to 31.1]) as compared with subjects in the lowest tertile. The difference in time spent in vigorous activities was greatly attenuated when further adjusted for blood lipids, cardiorespiratory fitness, fat distribution, resting heart rate, and mean arterial pressure (to-11.2 [95% CI:-29.4 to 7.0]). Similar results were found for the other stiffness estimates. Promoting vigorous intensity physical activities among the healthy young may, therefore, prevent arterial stiffness and related cardiovascular sequelae later in life, partly through its favorable impact on other biological cardiovascular risk factors

    A simulation toolkit for electroluminescence assessment in rare event experiments

    Full text link
    A good understanding of electroluminescence is a prerequisite when optimising double-phase noble gas detectors for Dark Matter searches and high-pressure xenon TPCs for neutrinoless double beta decay detection. A simulation toolkit for calculating the emission of light through electron impact on neon, argon, krypton and xenon has been developed using the Magboltz and Garfield programs. Calculated excitation and electroluminescence efficiencies, electroluminescence yield and associated statistical fluctuations are presented as a function of electric field. Good agreement with experiment and with Monte Carlo simulations has been obtained

    Shell model in the complex energy plane and two-particle resonances

    Get PDF
    An implementation of the shell-model to the complex energy plane is presented. The representation used in the method consists of bound single-particle states, Gamow resonances and scattering waves on the complex energy plane. Two-particle resonances are evaluated and their structure in terms of the single-particle degreees of freedom are analysed. It is found that two-particle resonances are mainly built upon bound states and Gamow resonances, but the contribution of the scattering states is also important.Comment: 20 pages, 9 figures, submitted to Phys.Rev.

    Systematics of proton emission

    Full text link
    A very simple formula is presented that relates the logarithm of the half-life, corrected by the centrifugal barrier, with the Coulomb parameter in proton decay processes. The corresponding experimental data lie on two straight lines which appear as a result of a sudden change in the nuclear shape marking two regions of deformation independently of the angular momentum of the outgoing proton. This feature provides a powerful tool to assign experimentally quantum numbers in proton emitters.Comment: 4 pages, 3 figure

    Role of dynamical particle-vibration coupling in reconciliation of the d3/2d_{3/2} puzzle for spherical proton emitters

    Get PDF
    It has been observed that decay rate for proton emission from d3/2d_{3/2} single particle state is systematically quenched compared with the prediction of a one dimensional potential model although the same model successfully accounts for measured decay rates from s1/2s_{1/2} and h11/2h_{11/2} states. We reconcile this discrepancy by solving coupled-channels equations, taking into account couplings between the proton motion and vibrational excitations of a daughter nucleus. We apply the formalism to proton emitting nuclei 160,161^{160,161}Re to show that there is a certain range of parameter set of the excitation energy and the dynamical deformation parameter for the quadrupole phonon excitation which reproduces simultaneously the experimental decay rates from the 2d3/2d_{3/2}, 3s1/2s_{1/2} and 1h11/2h_{11/2} states in these nuclei.Comment: RevTex, 12 pages, 4 eps figure

    Renormalization Group Approach to Generalized Cosmological models

    Get PDF
    We revisit here the problem of generalized cosmology using renormalization group approach. A complete analysis of these cosmologies, where specific models appear as asymptotic fixed-points, is given here along with their linearized stability analysis.Comment: 10 pages, to appear in the International Journal of Theoretical Physic

    The Crossing Statistic: Dealing with Unknown Errors in the Dispersion of Type Ia Supernovae

    Full text link
    We propose a new statistic that has been designed to be used in situations where the intrinsic dispersion of a data set is not well known: The Crossing Statistic. This statistic is in general less sensitive than `chi^2' to the intrinsic dispersion of the data, and hence allows us to make progress in distinguishing between different models using goodness of fit to the data even when the errors involved are poorly understood. The proposed statistic makes use of the shape and trends of a model's predictions in a quantifiable manner. It is applicable to a variety of circumstances, although we consider it to be especially well suited to the task of distinguishing between different cosmological models using type Ia supernovae. We show that this statistic can easily distinguish between different models in cases where the `chi^2' statistic fails. We also show that the last mode of the Crossing Statistic is identical to `chi^2', so that it can be considered as a generalization of `chi^2'.Comment: 14 pages, 5 figures. Paper restructured and extended and new interpretation of the method presented. New results concerning model selection. Treatment and error-analysis made fully model independent. References added. Accepted for publication in JCA

    Transfer Matrices and Partition-Function Zeros for Antiferromagnetic Potts Models. V. Further Results for the Square-Lattice Chromatic Polynomial

    Get PDF
    We derive some new structural results for the transfer matrix of square-lattice Potts models with free and cylindrical boundary conditions. In particular, we obtain explicit closed-form expressions for the dominant (at large |q|) diagonal entry in the transfer matrix, for arbitrary widths m, as the solution of a special one-dimensional polymer model. We also obtain the large-q expansion of the bulk and surface (resp. corner) free energies for the zero-temperature antiferromagnet (= chromatic polynomial) through order q^{-47} (resp. q^{-46}). Finally, we compute chromatic roots for strips of widths 9 <= m <= 12 with free boundary conditions and locate roughly the limiting curves.Comment: 111 pages (LaTeX2e). Includes tex file, three sty files, and 19 Postscript figures. Also included are Mathematica files data_CYL.m and data_FREE.m. Many changes from version 1: new material on series expansions and their analysis, and several proofs of previously conjectured results. Final version to be published in J. Stat. Phy

    Large Scale Pressure Fluctuations and Sunyaev-Zel'dovich Effect

    Get PDF
    The Sunyaev-Zel'dovich (SZ) effect associated with pressure fluctuations of the large scale structure gas distribution will be probed with current and upcoming wide-field small angular scale cosmic microwave background experiments. We study the generation of pressure fluctuations by baryons which are present in virialized dark matter halos and by baryons present in small overdensities. For collapsed halos, assuming the gas distribution is in hydrostatic equilibrium with matter density distribution, we predict the pressure power spectrum and bispectrum associated with the large scale structure gas distribution by extending the dark matter halo approach which describes the density field in terms of correlations between and within halos. The projected pressure power spectrum allows a determination of the resulting SZ power spectrum due to virialized structures. The unshocked photoionized baryons present in smaller overdensities trace the Jeans-scale smoothed dark matter distribution. They provide a lower limit to the SZ effect due to large scale structure in the absence of massive collapsed halos. We extend our calculations to discuss higher order statistics, such as bispectrum and skewness in SZ data. The SZ-weak lensing cross-correlation is suggested as a probe of correlations between dark matter and baryon density fields, while the probability distribution functions of peak statistics of SZ halos in wide field CMB data can be used as a probe of cosmology and non-Gaussian evolution of large scale structure pressure fluctuations.Comment: 16 pages, 9 figures; Revised with expanded discussions. Phys. Rev. D. (in press
    • 

    corecore