5,668 research outputs found

    Capacitors can radiate - some consequences of the two-capacitor problem with radiation

    Full text link
    We fill a gap in the arguments of Boykin et al [American Journal of Physics, Vol 70 No. 4, pp 415-420 (2002)] by not invoking an electric current loop (i.e. magnetic dipole model) to account for the radiation energy loss, since an obvious corollary of their results is that the capacitors should radiate directly even if the connecting wires are shrunk to zero length. That this is so is shown here by a direct derivation of capacitor radiation using an oscillating electric dipole radiator model for the capacitors as well as the alternative less widely known magnetic 'charge' current loop representation for an electric dipole [see for example "Electromagnetic Waves" by S.A.Schlekunoff, van Nostrand (1948)]. Implications for Electromagnetic Compliance (EMC) issues as well as novel antenna designs further motivate the purpose of this paper.Comment: 5 Pages with No figure

    High orders of Weyl series for the heat content

    Full text link
    This article concerns the Weyl series of spectral functions associated with the Dirichlet Laplacian in a dd-dimensional domain with a smooth boundary. In the case of the heat kernel, Berry and Howls predicted the asymptotic form of the Weyl series characterized by a set of parameters. Here, we concentrate on another spectral function, the (normalized) heat content. We show on several exactly solvable examples that, for even dd, the same asymptotic formula is valid with different values of the parameters. The considered domains are dd-dimensional balls and two limiting cases of the elliptic domain with eccentricity ϵ\epsilon: A slightly deformed disk (ϵ→0\epsilon\to 0) and an extremely prolonged ellipse (ϵ→1\epsilon\to 1). These cases include 2D domains with circular symmetry and those with only one shortest periodic orbit for the classical billiard. We analyse also the heat content for the balls in odd dimensions dd for which the asymptotic form of the Weyl series changes significantly.Comment: 20 pages, 1 figur

    Relativistic and Radiative Corrections to the Mollow Spectrum

    Get PDF
    The incoherent, inelastic part of the resonance fluorescence spectrum of a laser-driven atom is known as the Mollow spectrum [B. R. Mollow, Phys. Rev. 188, 1969 (1969)]. Starting from this level of description, we discuss theoretical foundations of high-precision spectroscopy using the resonance fluorescence light of strongly laser-driven atoms. Specifically, we evaluate the leading relativistic and radiative corrections to the Mollow spectrum, up to the relative orders of (Z alpha)^2 and alpha(Z alpha)^2, respectively, and Bloch-Siegert shifts as well as stimulated radiative corrections involving off-resonant virtual states. Complete results are provided for the hydrogen 1S-2P_{1/2} and 1S-2P_{3/2} transitions; these include all relevant correction terms up to the specified order of approximation and could directly be compared to experimental data. As an application, the outcome of such experiments would allow for a sensitive test of the validity of the dressed-state basis as the natural description of the combined atom-laser system.Comment: 20 pages, 1 figure; RevTe

    Perturbation theory in radial quantization approach and the expectation values of exponential fields in sine-Gordon model

    Get PDF
    A perturbation theory for Massive Thirring Model (MTM) in radial quantization approach is developed. Investigation of the twisted sector in this theory allows us to calculate the vacuum expectation values of exponential fields expiaphi(0) exp iaphi (0) of the sine-Gordon theory in first order over Massive Thirring Models coupling constant. It appears that the apparent difficulty in radial quantization of massive theories, namely the explicite ''time'' dependence of the Hamiltonian, may be successfully overcome. The result we have obtained agrees with the exact formula conjectured by Lukyanov and Zamolodchikov and coincides with the analogous calculations recently carried out in dual angular quantization approach by one of the authors.Comment: 16 pages, no figures, LaTe

    Effects of the Lattice Discreteness on a Soliton in the Su-Schrieffer-Heeger Model

    Full text link
    In this paper we analytically study the effects of the lattice discreteness on the electron band in the SSH model. We propose a modified version of the TLM model which is derived from the SSH model using a continuum approximation. When a soliton is induced in the electron-lattice system, the electron scattering states both at the bottom of the valence band and the top of the conduction band are attracted to the soliton. This attractive force induces weakly localized electronic states at the band edges. Using the modified version of the TLM model, we have succeeded in obtaining analytical solutions of the weakly localized states and the extended states near the bottom of the valence band and the top of the conduction band. This band structure does not modify the order parameters. Our result coincides well with numerical simulation works.Comment: to be appear in J.Phys.Soc.Jpn. Figures should be requested to the author. They will be sent by the conventional airmai

    Self-force of a point charge in the space-time of a symmetric wormhole

    Full text link
    We consider the self-energy and the self-force for an electrically charged particle at rest in the wormhole space-time. We develop general approach and apply it to two specific profiles of the wormhole throat with singular and with smooth curvature. The self-force for these two profiles is found in manifest form; it is an attractive force. We also find an expression for the self-force in the case of arbitrary symmetric throat profile. Far from the throat the self-force is always attractive.Comment: 18 pages, 3 figures Comments: corrected pdf, enlarged pape

    Relativistic ideal Fermi gas at zero temperature and preferred frame

    Full text link
    We discuss the limit T->0 of the relativistic ideal Fermi gas of luxons (particles moving with the speed of light) and tachyons (hypothetical particles faster than light) based on observations of our recent paper: K. Kowalski, J. Rembielinski and K.A. Smolinski, Phys. Rev. D, 76, 045018 (2007). For bradyons this limit is in fact the nonrelativistic one and therefore it is not studied herein

    Flexible insurance for long-term care: A study of stated preferences

    Full text link
    Aging societies need efficient and flexible systems to finance care for the frail elderly. We study pre-retirees' demand for flexible insurance that can finance informal long-term care by paying income in poor health states instead of reimbursing formal care costs. We collect and analyze stated preferences for this long-term care income product, and preferences for informal care. When asked to allocate wealth to a life annuity, a liquid investment and flexible long-term care insurance, around 75% of our sample of 1008 pre-retirees choose some long-term care cover. Study participants treat long-term care income insurance as a complement to informal care from their families. Females who expect to rely exclusively on extensive care from family members prefer more cover than similar males. We also find that if long-term care income insurance were available, some healthier seniors would purchase additional longevity insurance, using liquid funds otherwise set aside to self-insure long-term care risk

    Laplace transform of spherical Bessel functions

    Get PDF
    We provide a simple analytic formula in terms of elementary functions for the Laplace transform j_{l}(p) of the spherical Bessel function than that appearing in the literature, and we show that any such integral transform is a polynomial of order l in the variable p with constant coefficients for the first l-1 powers, and with an inverse tangent function of argument 1/p as the coefficient of the power l. We apply this formula for the Laplace transform of the memory function related to the Langevin equation in a one-dimensional Debye model.Comment: 5 pages LATEX, no figures. Accepted 2002, Physica Script

    Asthma - is survival good enough?

    Get PDF
    Advances in asthma management, particularly the introduction of controller medication of which inhaled corticosteroids are the most important, has resulted in a steady decline in asthma mortality in most countries. This is usually accompanied by a decline in episodes of near-fatal asthma attacks and hospitalisations, and a reduction in other indicators of asthma morbidity. These gains have led to a shift in thinking on the management of asthma, away from simply preventing death and hospitalisations, toward achieving and maintaining sustained control of all clinical features
    • …
    corecore