33,244,136 research outputs found

    Electrostatic image effects for counter-ions between charged planar walls

    Full text link
    We study the effect of dielectric inhomogeneities on the interaction between two planparallel charged surfaces with oppositely charged mobile charges in between. The dielectric constant between the surfaces is assumed to be different from the dielectric constant of the two semiinfinite regions bounded by the surfaces, giving rise to electrostatic image interactions. We show that on the weak coupling level the image charge effects are generally small, making their mark only in the second order fluctuation term. However, in the strong coupling limit, the image effects are large and fundamental. They modify the interactions between the two surfaces in an essential way. Our calculations are particularly useful in the regime of parameters where computer simulations would be difficult and extremely time consuming due to the complicated nature of the long range image potentials.Comment: 21 pages, 8 figure

    Josephson oscillation of a superfluid Fermi gas

    Full text link
    Using the complete numerical solution of a time-dependent three-dimensional mean-field model we study the Josephson oscillation of a superfluid Fermi gas (SFG) at zero temperature formed in a combined axially-symmetric harmonic plus one-dimensional periodic optical-lattice (OL) potentials after displacing the harmonic trap along the axial OL axis. We study the dependence of Josephson frequency on the strength of the OL potential. The Josephson frequency decreases with increasing strength as found in the experiment of Cataliotti et al. [Science 293 (2001) 843] for a Bose-Einstein condensate and of the experiment of Pezze et al. [Phys. Rev. Lett. 93 (2004) 120401] for an ideal Fermi gas. We demonstrate a breakdown of Josephson oscillation in the SFG for a large displacement of the harmonic trap. These features of Josephson oscillation of a SFG can be tested experimentally.Comment: 7 pages, 10 figure

    Emergence of superfluid transport in a dynamical system of ultracold atoms

    Full text link
    The dynamics of a Bose-Einstein condensate is studied theoretically in a combined periodic plus harmonic external potential. Different dynamical regimes of stable and unstable collective dipole and Bloch oscillations are analysed in terms of a quantum mechanical pendulum model. Nonlinear interactions are shown to counteract quantum-mechanical dephasing and lead to phase-coherent, superfluid transport

    Modelling nucleon-nucleon scattering above 1 GeV

    Full text link
    Motivated by the recent measurement of proton-proton spin-correlation parameters up to 2.5 GeV laboratory energy, we investigate models for nucleon-nucleon (NN) scattering above 1 GeV. Signatures for a gradual failure of the traditional meson model with increasing energy can be clearly identified. Since spin effects are large up to tens of GeV, perturbative QCD cannot be invoked to fix the problems. We discuss various theoretical scenarios and come to the conclusion that we do not have a clear phenomenological understanding of the spin-dependence of the NN interaction above 1 GeV.Comment: 36 pages, 8 figure

    Electromagnetic form factors of the baryon octet in the perturbative chiral quark model

    Full text link
    We apply the perturbative chiral quark model at one loop to analyze the electromagnetic form factors of the baryon octet. The analytic expressions for baryon form factors, which are given in terms of fundamental parameters of low-energy pion-nucleon physics (weak pion decay constant, axial nucleon coupling, strong pion-nucleon form factor), and the numerical results for baryon magnetic moments, charge and magnetic radii are presented. Our results are in good agreement with experimental data.Comment: 15 pages, 6 figures, to be published in Eur. Phys. J.

    Tracking and data system support for Surveyor mission 5, volume 3

    Get PDF
    Surveyor 5 tracking and data system activities evaluated from planning to final flight stage

    Access to undergraduate research experiences at a large research university

    Full text link
    The American Physical Society recently released a statement calling on all university physics departments to provide or facilitate access to research experiences for all undergraduate students. In response, we investigated the current status of access to undergraduate research at University of Colorado Boulder (CU), a large research institution where the number of undergraduate physics majors outnumber faculty by roughly ten to one. We created and administered two surveys within CU's Physics Department: one probed undergraduate students' familiarity with, and participation in, research; the other probed faculty members' experiences as research mentors to undergraduates. We describe the development of these instruments, our results, and our corresponding evidence-based recommendations for improving local access to undergraduate research experiences. Reflecting on our work, we make several connections to an institutional change framework and note how other universities and colleges might adapt our process.Comment: 4 pages, 3 figures, 1 table; Submitted to 2015 PERC Proceeding

    Peran Gaya Kepemimpinan Transformasional Memoderasi Pengaruh Motivasi Intrinsik dan Kecerdasan Emosional terhadap Kinerja Guru (Studi Kasus pada SMA Negeri di Kecamatan Pati Kabupaten Pati)

    Full text link
    This research is intended to examine the influence of motivation intrinsic and emotional intelligence to the state senior high school teachers' work performance with the moderation of transformational leadership style. The specific purpose of this research is to examine the role of transformational leadership style moderates the influence of intrinsic motivation and emotional intelligence to the teachers' work performance. The USAge of this research is to explain and expand the previous research about the role of transformational leadership style moderates the influence of intrinsic motivation and emotional intelligence to the teachers' work performance. This research used the population of 116 teachers of state senior high school in Pati District, Pati Regency. The technique of sample collection used in this research is non-probability sampling with the purposive method. The analysis technique used in this research is regression model moderate quasi. Based on the research result can be conduded that: intrinsic motivation influences teachers' work performance, emotional intelligence influences the teachers' work performance, transformational leadership style do not moderate the influence of intrinsic motivation to teachers' work performance, , transformational leadership style strengthen the influence of emotional intelligence to the teachers' workperformance

    Peran Budaya Organisasional Memoderasi Pengaruh Motivasi dan Komitmen Organisasional terhadap Kinerja Guru (Studi pada Guru Mts Se Kecamatan Kedungwuni Kabupaten Pekalongan)

    Full text link
    This study aims to determine the role of organizational culture moderates the influence of motivation and organizational commitment on MTs teachers performance in Kedungwuni districtof Pekalongan regency. Research was conducted MTs teachers in Kedungwuni district as many as 141 people using the population research. The statistical analyze used by the validity test,reliability test, normality test, classical assumptions, goodness of fit model and hypothesis test. Based on the survey results revealed that the motivation significant and positive impact onteachers performance; organizational commitment significant and positive impact on teachers performance; organizational culture significant and positive impact on teachers performance;organizational culture strengthen the effect of motivation on teachers performance and organizational culture strengthen the influence of organizational commitment to teachers performanc
    corecore