8,218 research outputs found

    Remarks on the derivation of Gross-Pitaevskii equation with magnetic Laplacian

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    The effective dynamics for a Bose-Einstein condensate in the regime of high dilution and subject to an external magnetic field is governed by a magnetic Gross-Pitaevskii equation. We elucidate the steps needed to adapt to the magnetic case the proof of the derivation of the Gross-Pitaevskii equation within the "projection counting" scheme

    Rotational excitation of methylidynium (CH+) by a helium atom at high temperature

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    We aim to obtain accurate rate coefficients for the collisional excitation of CH+ by He for high gas temperatures. The ab initio coupled-cluster [CCSD(T)] approximation was used to compute the interaction potential energy. Cross sections are then derived in the close coupling (CC) approach and rate coefficients inferred by averaging these cross sections over a Maxwell-Boltzmann distribution of kinetic energies. Cross sections are calculated up to 10'000 cm^-1 for J ranging from 0 to 10. Rate coefficients are obtained at high temperatures up to 2000 K.Comment: 4 pages, 3 figures, table with rate coefficients, accepted for publication by A&

    Stark shift of the Cs clock transition frequency: a new experimental approach

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    A room temperature 19-channel magnetic field mapping device for cardiac signals

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    We present a multichannel cardiac magnetic field imaging system built in Fribourg from optical double-resonance Cs vapor magnetometers. It consists of 25 individual sensors designed to record magnetic field maps of the beating human heart by simultaneous measurements on a grid of 19 points over the chest. The system is operated as an array of second order gradiometers using sophisticated digitally controlled feedback loops.Comment: 3 pages, 3 figures, submitted to Applied Physics Letter

    Experiences of the Pre and Post Retirement Period of Female Elite Artistic Gymnasts: An Exploratory Study

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    This study explored retirement experiences of eight, female, former elite artistic gymnasts. Particular attention was afforded to coping strategies employed and dynamics of gymnast’s relationships with significant members of their social support network, in light of identity impact, across the retirement transition period. Retrospective, semi-structured interviews were conducted, transcripts were analysed through content analysis, and represented via pen profiles. Pre-retirement planning emerged as fundamental to the quality of the retirement transition. Keeping in contact with sport was the most frequently cited coping strategy. Social support networks adjusted pre- to post-retirement, identifying parents and partners as the consistent members of these networks across the transition. Findings provide formative recommendations to enhance the post-career education within current lifestyle management programmes, and for the design of a transitional support programme for gymnasts. The study findings may be of relevance for policy and practice in elite sport transitions more generally

    Experiences of the Pre and Post Retirement Period of Female Elite Artistic Gymnasts: An Exploratory Study

    Get PDF
    his study explored retirement experiences of eight, female, former elite artistic gymnasts. Particular attention was afforded to coping strategies employed and dynamics of gymnast’s relationships with significant members of their social support network, in light of identity impact, across the retirement transition period. Retrospective, semi-structured interviews were conducted, transcripts were analysed through content analysis, and represented via pen profiles. Pre-retirement planning emerged as fundamental to the quality of the retirement transition. Keeping in contact with sport was the most frequently cited coping strategy. Social support networks adjusted pre- to post-retirement, identifying parents and partners as the consistent members of these networks across the transition. Findings provide formative recommendations to enhance the post-career education within current lifestyle management programmes, and for the design of a transitional support programme for gymnasts. The study findings may be of relevance for policy and practice in elite sport transitions more generally

    Effective non-linear dynamics of binary condensates and open problems

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    We report on a recent result concerning the effective dynamics for a mixture of Bose-Einstein condensates, a class of systems much studied in physics and receiving a large amount of attention in the recent literature in mathematical physics; for such models, the effective dynamics is described by a coupled system of non-linear Sch\"odinger equations. After reviewing and commenting our proof in the mean field regime from a previous paper, we collect the main details needed to obtain the rigorous derivation of the effective dynamics in the Gross-Pitaevskii scaling limit.Comment: Corrected typos, updated reference

    Resonant Formation of dμtd\mu t Molecules in Deuterium: An Atomic Beam Measurement of Muon Catalyzed dt Fusion

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    Resonant formation of dμtd\mu t molecules in collisions of muonic tritium (μt\mu t) on D2_2 was investigated using a beam of μt\mu t atoms, demonstrating a new direct approach in muon catalyzed fusion studies. Strong epithermal resonances in dμtd\mu t formation were directly revealed for the first time. From the time-of-flight analysis of 2036±1162036\pm 116 dtdt fusion events, a formation rate consistent with 0.73±(0.16)meas±(0.09)model0.73\pm (0.16)_{meas} \pm (0.09)_{model} times the theoretical prediction was obtained. For the largest peak at a resonance energy of 0.423±0.0370.423 \pm 0.037 eV, this corresponds to a rate of (7.1±1.8)×109(7.1 \pm 1.8) \times 10^9 s−1^{-1}, more than an order of magnitude larger than those at low energies.Comment: To appear in Phys. Rev. Let

    Sensitivity of double resonance alignment magnetometers

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    We present an experimental study of the intrinsic magnetometric sensitivity of an optical/rf-frequency double resonance magnetometer in which linearly polarized laser light is used in the optical pumping and detection processes. We show that a semi-empirical model of the magnetometer can be used to describe the magnetic resonance spectra. Then, we present an efficient method to predict the optimum operating point of the magnetometer, i.e., the light power and rf Rabi frequency providing maximum magnetometric sensitivity. Finally, we apply the method to investigate the evolution of the optimum operating point with temperature. The method is very efficient to determine relaxation rates and thus allowed us to determine the three collisional disalignment cross sections for the components of the alignment tensor. Both first and second harmonic signals from the magnetometer are considered and compared
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