484 research outputs found

    Formulation of cosmic-ray solar daily variation and its seasonal variation, produced from generalized stationary anisotropy of solar origin

    Get PDF
    In previous papers, a formulation was presented of cosmic ray daily variations produced from solar anisotropies stationary through a year, and also of their annual (or seasonal) modulation caused by the annual variation of the rotation axis of the Earth relative to that of the Sun. These anisotropies are symmetric for an arbitrary rotation around an axis. From observations of the tri-diurnal variation, it has been suggested that solar anisotropies also contain some axis-asymmetric term of the third order with respect to the IMF-axis. This suggestion has recently found support in a theoretical study by Munakata and Nagashima. According to their results, the terms of axis-asymmetry with respect to IMF-axis appear also in the 2nd order anisotropy, together with some different kinds of axis-symmetric terms. The contribution of these anisotropies to the daily variation is different from that of those discussed previously. The above mentioned formulation is extended to a case of a generalized anisotropy

    IMF-sense-dependent cosmic ray anisotropy produced from diffusion-convection in heliosphere

    Get PDF
    It was demonstrated that an interplanetary magnetic field (IMF) sense dependent 2nd order anisotropy is produced by the diffusion convection of cosmic rays in the heliomagnetosphere. The result implies that the anisotropy cannot be expressed only by the pitch angle with respect to the IMF axis

    Internal states of model isotropic granular packings. I. Assembling process, geometry and contact networks

    Get PDF
    This is the first paper of a series of three, reporting on numerical simulation studies of geometric and mechanical properties of static assemblies of spherical beads under an isotropic pressure. Frictionless systems assemble in the unique random close packing (RCP) state in the low pressure limit if the compression process is fast enough, slower processes inducing traces of crystallization, and exhibit specific properties directly related to isostaticity of the force-carrying structure. The different structures of frictional packings assembled by various methods cannot be classified by the sole density. While lubricated systems approach RCP densities and coordination number z^*~=6 on the backbone in the rigid limit, an idealized "vibration" procedure results in equally dense configurations with z^*~=4.5. Near neighbor correlations on various scales are computed and compared to available laboratory data, although z^* values remain experimentally inaccessible. Low coordination packings have many rattlers (more than 10% of the grains carry no force), which should be accounted for on studying position correlations, and a small proportion of harmless "floppy modes" associated with divalent grains. Frictional packings, however slowly assembled under low pressure, retain a finite level of force indeterminacy, except in the limit of infinite friction.Comment: 29 pages. Published in Physical Review

    Heteroepitaxial growth of ferromagnetic MnSb(0001) films on Ge/Si(111) virtual substrates

    Get PDF
    Molecular beam epitaxial growth of ferromagnetic MnSb(0001) has been achieved on high quality, fully relaxed Ge(111)/Si(111) virtual substrates grown by reduced pressure chemical vapor deposition. The epilayers were characterized using reflection high energy electron diffraction, synchrotron hard X-ray diffraction, X-ray photoemission spectroscopy, and magnetometry. The surface reconstructions, magnetic properties, crystalline quality, and strain relaxation behavior of the MnSb films are similar to those of MnSb grown on GaAs(111). In contrast to GaAs substrates, segregation of substrate atoms through the MnSb film does not occur, and alternative polymorphs of MnSb are absent

    Internal states of model isotropic granular packings. III. Elastic properties

    Get PDF
    In this third and final paper of a series, elastic properties of numerically simulated isotropic packings of spherical beads assembled by different procedures and subjected to a varying confining pressure P are investigated. In addition P, which determines the stiffness of contacts by Hertz's law, elastic moduli are chiefly sensitive to the coordination number, the possible values of which are not necessarily correlated with the density. Comparisons of numerical and experimental results for glass beads in the 10kPa-10MPa range reveal similar differences between dry samples compacted by vibrations and lubricated packings. The greater stiffness of the latter, in spite of their lower density, can hence be attributed to a larger coordination number. Voigt and Reuss bounds bracket bulk modulus B accurately, but simple estimation schemes fail for shear modulus G, especially in poorly coordinated configurations under low P. Tenuous, fragile networks respond differently to changes in load direction, as compared to load intensity. The shear modulus, in poorly coordinated packings, tends to vary proportionally to the degree of force indeterminacy per unit volume. The elastic range extends to small strain intervals, in agreement with experimental observations. The origins of nonelastic response are discussed. We conclude that elastic moduli provide access to mechanically important information about coordination numbers, which escape direct measurement techniques, and indicate further perspectives.Comment: Published in Physical Review E 25 page

    Self‐management for adults with epilepsy: Aggregate Managing Epilepsy Well Network findings on depressive symptoms

    Full text link
    ObjectiveTo assess depressive symptom outcomes in a pooled sample of epilepsy self‐management randomized controlled trials (RCTs) from the Managing Epilepsy Well (MEW) Network integrated research database (MEW DB).MethodsFive prospective RCTs involving 453 adults with epilepsy compared self‐management intervention (n = 232) versus treatment as usual or wait‐list control outcomes (n = 221). Depression was assessed with the nine‐item Patient Health Questionnaire. Other variables included age, gender, race, ethnicity, education, income, marital status, seizure frequency, and quality of life. Follow‐up assessments were collapsed into a visit 2 and a visit 3; these were conducted postbaseline.ResultsMean age was 43.5 years (SD = 12.6), nearly two‐thirds were women, and nearly one‐third were African American. Baseline sample characteristics were mostly similar in the self‐management intervention group versus controls. At follow‐up, the self‐management group had a significantly greater reduction in depression compared to controls at visit 2 (P < .0001) and visit 3 (P = .0002). Quality of life also significantly improved in the self‐management group at visit 2 (P = .001) and visit 3 (P = .005).SignificanceAggregate MEW DB analysis of five RCTs found depressive symptom severity and quality of life significantly improved in individuals randomized to self‐management intervention versus controls. Evidence‐based epilepsy self‐management programs should be made more broadly available in neurology practices.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/151320/1/epi16322_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/151320/2/epi16322.pd

    An Elasto-plastic Model for Liquefiable Sands Subjected to Torsional Shear Loadings

    Get PDF
    This paper presents a modeling procedure for simulating the monotonic undrained torsional shear behavior of sands, including stress-strain relationship, and excess pore water pressure generation, while considering the void ratio and stress level dependence of stress-strain-dilatancy behavior of sand. A unique set of soil parameters is required by the model to satisfactorily predict the undrained behavior of loose and dense Toyoura sand over a wide range of initial void ratios and confining pressures, as proven by simulating experimental data produced by the authors and found in the literature
    • 

    corecore