3,767 research outputs found

    Kinematic variations due to changes in pace during men's and women's 5 km road running

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    The purpose of this study was to investigate variations in kinematic parameters in men's and women's 5 km road racing. Athletes often vary their pace and changes particularly tend to occur towards the end of a race due to fatigue and sprint finishes. Twenty competitive distance runners (10 male, 10 female) were videoed as they completed the English National 5 km championships. Three-dimensional kinematic data were analysed using motion analysis software (SIMI, Munich). Data were recorded at 950 m, 2,400 m and 3,850 m. Repeated measures ANOVA showed significant decreases in speed due to reduced step length and cadence in both men and women. These decreases predominantly occurred between the first two measurement points. The hip, knee, ankle and shoulder angles at both initial contact and toe-off did not change significantly, but there were significant reductions in the elbow angle for both men (at initial contact) and women (at toe-off)

    Transport properties of single atoms

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    We present a systematic study of the ballistic electron conductance through sp and 3d transition metal atoms attached to copper and palladium crystalline electrodes. We employ the 'ab initio' screened Korringa-Kohn-Rostoker Green's function method to calculate the electronic structure of nanocontacts while the ballistic transmission and conductance eigenchannels were obtained by means of the Kubo approach as formulated by Baranger and Stone. We demonstrate that the conductance of the systems is mainly determined by the electronic properties of the atom bridging the macroscopic leads. We classify the conducting eigenchannels according to the atomic orbitals of the contact atom and the irreducible representations of the symmetry point group of the system that leads to the microscopic understanding of the conductance. We show that if impurity resonances in the density of states of the contact atom appear at the Fermi energy, additional channels of appropriate symmetry could open. On the other hand the transmission of the existing channels could be blocked by impurity scattering.Comment: RevTEX4, 9 pages, 9 figure

    Radiogenic power and geoneutrino luminosity of the Earth and other terrestrial bodies through time

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    We report the Earth's rate of radiogenic heat production and (anti)neutrino luminosity from geologically relevant short-lived radionuclides (SLR) and long-lived radionuclides (LLR) using decay constants from the geological community, updated nuclear physics parameters, and calculations of the β\beta spectra. We track the time evolution of the radiogenic power and luminosity of the Earth over the last 4.57 billion years, assuming an absolute abundance for the refractory elements in the silicate Earth and key volatile/refractory element ratios (e.g., Fe/Al, K/U, and Rb/Sr) to set the abundance levels for the moderately volatile elements. The relevant decays for the present-day heat production in the Earth (19.9±3.019.9\pm3.0 TW) are from 40^{40}K, 87^{87}Rb, 147^{147}Sm, 232^{232}Th, 235^{235}U, and 238^{238}U. Given element concentrations in kg-element/kg-rock and density ρ\rho in kg/m3^3, a simplified equation to calculate the present day heat production in a rock is: h[μW m3]=ρ(3.387×103K+0.01139Rb+0.04595Sm+26.18Th+98.29U) h \, [\mu \text{W m}^{-3}] = \rho \left( 3.387 \times 10^{-3}\,\text{K} + 0.01139 \,\text{Rb} + 0.04595\,\text{Sm} + 26.18\,\text{Th} + 98.29\,\text{U} \right) The radiogenic heating rate of Earth-like material at Solar System formation was some 103^3 to 104^4 times greater than present-day values, largely due to decay of 26^{26}Al in the silicate fraction, which was the dominant radiogenic heat source for the first 10\sim10 Ma. Assuming instantaneous Earth formation, the upper bound on radiogenic energy supplied by the most powerful short-lived radionuclide 26^{26}Al (t1/2t_{1/2} = 0.7 Ma) is 5.5  ×  \;\times\;1031^{31} J, which is comparable (within a factor of a few) to the planet's gravitational binding energy.Comment: 28 pages, 6 figures, 5 table

    The monitoring system for the aerogel Cherenkov counter of the BELLE detector

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    We report on a design and performances of a monitoring system developed for the aerogel Cherenkov counters (ACC) of the BELLE detector. The system consists of blue LEDs, a diffuser box, and optical distributors which distribute the LED light to the ACC modules. The employed LED (NSPB series) has been observed to have high reliability on the long term stability and the temprature dependence. The diffuser box is employed to reduce the intrinsic non-uniformity of the LED light intensity. The overall performances of the present monitoring system on uniformity and intensity of the light output have been found to satisfy all the requirements for the monitoring.Comment: 24 pages, LaTeX, 13 eps figures, to be published in Nucl. Instrum. and Meth. A. Postscript file (4.5 MB) is available at http://www-hep.phys.saga-u.ac.jp/~murakami/paper/xxx_accmon.p

    The Effects of Religion on Depression and Suicide Rates in the United States

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    Depression and suicide are major health problems in the United States and in the World.  According to the American Foundation for Suicide Prevention (2014), “Suicide claims more lives than war, murder, and natural disasters combined (p. 1).”  Many of the victims of suicide were also victims of depression.  Research has shown that those who are religious are less likely to suffer from depression and less likely to commit suicide.  This study shows that for the three major religious groups in the United States, evangelical Protestants, mainline Protestants, and Catholics, number of cases of depression are reduced, but the number of suicides increases for evangelical Protestants.  Depression may be reduced since religion provides many benefits to individuals including a social network whereby those in distress can seek comfort from others.  Furthermore, those who are religious are also more secure in their beliefs of life after death, personal salvation, and the forgiveness of their sins which may reduce pressures put on them by everyday life.  However, it may  be that feelings of inadequacy over not being able to live up to the strict teachings of some evangelical religious groups and the fact that anyone questioning the strict beliefs of the church should be ostracized, could be contributing factors to the stress, trauma, and lack of self worth, that lead to thoughts of suicide. Keywords: religion, evangelical Protestants, mainline Protestants, Catholics, depression, suicid

    Fine-structure in the nonthermal X-ray emission of SNR RX J1713.7-3946 revealed by Chandra

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    We present morphological and spectroscopic studies of the northwest rim of the supernova remnant RX J1713.7-3946 based on observations by the Chandra X-ray observatory. We found a complex network of nonthermal (synchrotron) X-ray filaments, as well as a 'void' type structure -- a dim region of a circular shape -- in the northwest rim. It is remarkable that despite distinct brightness variations, the X-ray spectra everywhere in this region can be well fitted with a power-law model with photon index around 2.3. We briefly discuss some implications of these results and argue that the resolved X-ray features in the northwest rim may challenge the perceptions of standard (diffusive shock-acceleration) models concerning the production, propagation and radiation of relativistic particles in supernova remnants.Comment: 8 pages, 9 figures; accepted for publication in A&A; significant additions for publication in Main journal (previous version was for A&A Letter); a manuscript (as a single PDF file, 501kb) including all figures is available at http://www.astro.isas.ac.jp/~uchiyama/publication/h4106.pd

    Motion-Induced Magnetic Resonance of Rb Atoms in a Periodic Magnetostatic Field

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    We demonstrate that transitions between Zeeman-split sublevels of Rb atoms are resonantly induced by the motion of the atoms (velocity: about 100 m/s) in a periodic magnetostatic field (period: 1 mm) when the Zeeman splitting corresponds to the frequency of the magnetic field experienced by the moving atoms. A circularly polarized laser beam polarizes Rb atoms with a velocity selected using the Doppler effect and detects their magnetic resonance in a thin cell, to which the periodic field is applied with the arrays of parallel current-carrying wires.Comment: 4 pages, 4 figures; minor corrections, Ref. [9] removed, published in PR

    K0(K0ˉ)K^0(\bar{K^0}) Production in Two-Photon Processes at TRISTAN

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    We have carried out an inclusive measurement of K0(K0ˉ)K^0(\bar{K^0}) production in two-photon processes at TRISTAN. The mean s\sqrt{s} was 58 GeV and the integrated luminosity was 199 pb1^{-1}. High-statistics KsK_s samples were obtained under such conditions as no-, anti-electron, and remnant-jet tags. The remnant-jet tag, in particular, allowed us, for the first time, to measure the cross sections separately for the resolved-photon and direct processes.Comment: 20 pages, Latex format, 4 figures and KEK-mark included. Table 1 revised. To be published in Phys. Lett.
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