114 research outputs found

    Restricted Work Due to Workplace Injuries: A Historical Perspective

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    In anticipation of upcoming data on worker characteristics and on case circumstances surrounding workplace injuries that result in job transfer or restricted work, new tabulations look at trends in the outcome of workplace injuries over the past several decade

    On graviton production in braneworld cosmology

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    We study braneworlds in a five dimensional bulk, where cosmological expansion is mimicked by motion through AdS5_5. We show that the five dimensional graviton reduces to the four dimensional one in the late time approximation of such braneworlds. Inserting a fixed regulator brane far from the physical brane, we investigate quantum graviton production due to the motion of the brane. We show that the massive Kaluza-Klein modes decouple completely from the massless mode and they are not generated at all in the limit where the regulator brane position goes to infinity. In the low energy limit, the massless four dimensional graviton obeys the usual 4d equation and is therefore also not generated in a radiation-dominated universe.Comment: 9 pages, minor changes, references correcte

    Exact closed form analytical solutions for vibrating cavities

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    For one-dimensional vibrating cavity systems appearing in the standard illustration of the dynamical Casimir effect, we propose an approach to the construction of exact closed-form solutions. As new results, we obtain solutions that are given for arbitrary frequencies, amplitudes and time regions. In a broad range of parameters, a vibrating cavity model exhibits the general property of exponential instability. Marginal behavior of the system manifests in a power-like growth of radiated energy.Comment: 17 pages, 7 figure

    Vibrating Cavities - A numerical approach

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    We present a general formalism allowing for efficient numerical calculation of the production of massless scalar particles from vacuum in a one-dimensional dynamical cavity, i.e. the dynamical Casimir effect. By introducing a particular parametrization for the time evolution of the field modes inside the cavity we derive a coupled system of first-order linear differential equations. The solutions to this system determine the number of created particles and can be found by means of numerical methods for arbitrary motions of the walls of the cavity. To demonstrate the method which accounts for the intermode coupling we investigate the creation of massless scalar particles in a one-dimensional vibrating cavity by means of three particular cavity motions. We compare the numerical results with analytical predictions as well as a different numerical approach.Comment: 28 pages, 19 figures, accepted for publication in J. Opt. B: Quantum Semiclass. Op

    Sport Psychology Utilization among College Football Coaches: Understanding College Football Coaches’ Attitudes about Sport Psychology

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    As the field of Sport Psychology (SP) continues to expand and become more embedded within college athletic programs, it is necessary to assess practices by which sport psychology providers can be effective in delivering services and accessing populations. Football represents a particular athletic subculture that paradoxically needs services but can be difficult to access. This current study examined perspectives of college football coaches in order to further expand the understanding of college football coaches’ knowledge about sport psychology by assessing coaches’ abilities to identify mental health concerns and their willingness to refer student- athletes to mental health services. Coaches revealed their beliefs about mental health concerns, barriers to accessing mental health services, as well as their perspective of the ideal characteristics of Sport Psychology Consultants (SPC), as it relates to the specific needs of college football players. Results can be used to inform best practices and provide practical implications for improving mental health and overall well-being among college student-athletes

    Fluctuations, dissipation and the dynamical Casimir effect

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    Vacuum fluctuations provide a fundamental source of dissipation for systems coupled to quantum fields by radiation pressure. In the dynamical Casimir effect, accelerating neutral bodies in free space give rise to the emission of real photons while experiencing a damping force which plays the role of a radiation reaction force. Analog models where non-stationary conditions for the electromagnetic field simulate the presence of moving plates are currently under experimental investigation. A dissipative force might also appear in the case of uniform relative motion between two bodies, thus leading to a new kind of friction mechanism without mechanical contact. In this paper, we review recent advances on the dynamical Casimir and non-contact friction effects, highlighting their common physical origin.Comment: 39 pages, 4 figures. Review paper to appear in Lecture Notes in Physics, Volume on Casimir Physics, edited by Diego Dalvit, Peter Milonni, David Roberts, and Felipe da Rosa. Minor changes, a reference adde

    Size constancy is preserved but afterimages are prolonged in typical individuals with higher degrees of self-reported autistic traits

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    Deficits in perceptual constancies from early infancy have been proposed to contribute to autism and exacerbate its symptoms (Hellendoorn et al., Frontiers in Psychology 6:1–16, 2015). Here, we examined size constancy in adults from the general population (N = 106) with different levels of self-reported autistic traits using an approach based on negative afterimages. The afterimage strength, as indexed by duration and vividness, was also quantified. In opposition to the Hellendoorn and colleagues’ model, we were unable to demonstrate any kind of relationship between abilities in size constancy and autistic traits. However, our results demonstrated that individuals with higher degrees of autistic traits experienced more persistent afterimages. We discuss possible retinal and post-retinal explanations for prolonged afterimages in people with higher levels of autistic traits
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