16,118 research outputs found

    Consistent services throughout the week for acute medical care.

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    People Who Punish or Reward Tend to Moralize Even Conventional Behaviour

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    Managers who have to reward or punish others may be prone to moralizing. This can create problems because it may make the manager less tolerant of errant behavior while others in the social group, who may be wary of moralizing attitudes, may react against the manager.York's Knowledge Mobilization Unit provides services and funding for faculty, graduate students, and community organizations seeking to maximize the impact of academic research and expertise on public policy, social programming, and professional practice. It is supported by SSHRC and CIHR grants, and by the Office of the Vice-President Research & Innovation. [email protected] www.researchimpact.c

    Entanglement distribution by an arbitrarily inept delivery service

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    We consider the scenario where a company C manufactures in bulk pure entangled pairs of particles, each pair intended for a distinct pair of distant customers. Unfortunately, its delivery service is inept - the probability that any given customer pair receives its intended particles is S, and the customers cannot detect whether an error has occurred. Remarkably, no matter how small S is, it is still possible for C to distribute entanglement by starting with non-maximally entangled pairs. We determine the maximum entanglement distributable for a given S, and also determine the ability of the parties to perform nonlocal tasks with the qubits they receive.Comment: 5 pages, 3 figures. v2 includes minor change

    The Energy Spectrum of Primary Cosmic Ray Electrons in Clusters of Galaxies and Inverse Compton Emission

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    Models for the evolution of the integrated energy spectrum of primary cosmic ray electrons in clusters of galaxies have been calculated, including the effects of losses due to inverse Compton (IC), synchrotron, and bremsstrahlung emission, and Coulomb losses to the intracluster medium (ICM). The combined time scale for these losses reaches a maximum of ~3e9 yr for electrons with a Lorentz factor ~300. Only clusters in which there has been a substantial injection of relativistic electrons since z <~ 1 will have any significant population of primary cosmic ray electrons at present. In typical models, there is a broad peak in the electron energy distribution extending to gamma~300, and a steep drop in the electron population beyond this. In clusters with current particle injection, there is a power-law tail of higher energy electrons with an abundance determined by the current rate of injection. A significant population of electrons with gamma~300, associated with the peak in the particle loss time, is a generic feature of the models. The IC and synchrotron emission from these models was calculated. In the models, EUV and soft X-ray emission are nearly ubiquitous. This emission is produced by electrons with gamma~300. The spectra are predicted to drop rapidly in going from the EUV to the X-ray band. The IC emission also extends down the UV, optical, and IR bands with a fairly flat spectrum. Hard X-ray (HXR) and diffuse radio emission due to high energy electrons (gamma~10e4) is present only in clusters which have current particle acceleration. Assuming that the electrons are accelerated in ICM shocks, one would only expect diffuse HXR/radio emission in clusters which are currently undergoing a large merger.Comment: Accepted for publication in the Astrophysical Journal, with minor revisons to wording for clarity and one additional reference. 19 pages with 16 embedded Postscript figures in emulateapj.sty. Abbreviated abstract belo

    Evaluation of the effectiveness of Eladi Keram for the treatment of acne vulgaris: a randomised controlled pilot study

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    Introduction: Acne is a multifactorial and common skin disease which can significantly affect the quality of life of sufferers. In this study, a topical herbal preparation traditionally used in Ayurvedic medicine was evaluated as a treatment for individuals with acne on their shoulders and backs. Methods: Study participants were randomly assigned either to treatment (Eladi Keram) or vehicle control (coconut oil) groups under double blind conditions and instructed on its daily home application. Standardised lesion counting and acne grading were conducted in accordance with US Food and Drug Administration guidelines and with reference to the Leeds Acne Grading Technique. Participants were assessed for severity of the condition at commencement and on day 28 of treatment. Results: The treatment group showed improvements of 42% (p < 0.005) on the Investigators Global Assessment scale, a 60% (p < 0.05) reduction in inflammatory lesions, a 59% (p < 0.05) reduction in non-inflammatory lesions, and a 59% (p < 0.005) reduction in combined lesion count. The control group showed no statistically significant changes for these criteria. Conclusion: This study is the first reported clinical evaluation of Eladi Keram as a treatment for acne and findings suggest that it could be effective in reducing inflammatory and non-inflammatory lesions, warranting further investigation by means of a larger scale clinical trial

    Turbulence and particle acceleration in collisionless supernovae remnant shocks: II- Cosmic-ray transport

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    Supernovae remnant shock waves could be at the origin of cosmic rays up to energies in excess of the knee (E≃3⋅1015E\simeq3\cdot 10^{15} eV) if the magnetic field is efficiently amplified by the streaming of accelerated particles in the shock precursor. This paper follows up on a previous paper \citep{pell05} which derived the properties of the MHD turbulence so generated, in particular its anisotropic character, its amplitude and its spectrum. In the present paper, we calculate the diffusion coefficients, also accounting for compression through the shock, and show that the predicted three-dimensional turbulence spectrum k⊄S3d(k∄,k⊄)∝k∄−1k⊄−αk_\perp S_{3\rm d}(k_\parallel,k_\perp)\propto k_\parallel^{-1}k_\perp^{-\alpha} (with k∄k_\parallel and k⊄k_\perp the wavenumber components along and perpendicular to the shock normal) generally leads to Bohm diffusion in the parallel direction. However, if the anisotropy is constrained by a relation of the form k∄∝k⊄2/3k_\parallel \propto k_\perp^{2/3}, which arises when the turbulent energy cascade occurs at a constant rate independent of scale, then the diffusion coefficient loses its Bohm scaling and scales as in isotropic Kolmogorov turbulence. We show that these diffusion coefficients allow to account for X-ray observations of supernova remnants. This paper also calculates the modification of the Fermi cycle due to the energy lost by cosmic rays in generating upstream turbulence and the concomittant steepening of the energy spectrum. Finally we confirm that cosmic rays can produced an amplified turbulence in young SNr during their free expansion phase such that the maximal energy is close to the knee and the spectral index is close to 2.3 in the warm phase of the interstellar mediumComment: 13 pages, 4 figures, accepted for publication in Astronomy & Astrophysics main journa

    The Identification of Infrared Synchrotron Radiation from Cassiopeia A

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    We report the discovery of polarized flux at 2.2 micron from the bright shell of the approximately 320 year old supernova remnant Cas A. The fractional polarizations are comparable at 6 cm and 2.2 micron, and the polarization angles are similar, demonstrating that synchrotron radiation from the same relativistic plasma is being observed at these widely separated wavebands. The relativistic electrons radiating at 2.2 micron have an energy of ~ 150 GeV, (gamma ~ 3e5), assuming an ~500 microGauss magnetic field. The total intensity at 2.2 micron lies close to the power law extrapolation from radio frequencies, showing that relativistic particle acceleration is likely an ongoing process; the infrared emitting electrons were accelerated no longer than ~80 years ago. There is a small but significant concave curvature to the spectrum, as expected if the accelerating shocks have been modified by the back pressure of the cosmic rays; given calibration uncertainties, this conclusion must be considered tentative at present. The 2.2 micron polarization angles and the emission-line filaments observed by HST are both offset from the local radial direction by 10 - 20 degrees, providing evidence that the magnetic fields in Cas A are generated by Rayleigh-Taylor instabilities in the decelerating ejecta.Comment: 11 pages, 3 figures, accepted for publication Ap

    Implications of Variability Patterns observed in TeV Blazars on the Structure of the Inner Jet

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    The recent long look X-ray observations of TeV blazars have revealed many important new features concerning their time variability. In this paper, we suggest a physical interpretation for those features based on the framework of the internal and external shock scenarios. We present a simplified model applicable to TeV blazars, and investigate through simulations how each of the model parameters would affect to the observed light curve or spectrum. In particular, we show that the internal shock scenario naturally leads to all the observed variability properties including the structure function, but for it to be applicable, the fractional fluctuation of the initial bulk Lorentz factors must be small, with sigma_gamma / gamma_average < 0.01. This implies very low dynamical efficiency of the internal shock scenario. We also suggest that several observational quantities -- such as the characteristic time scale, the relative amplitude of flares as compared to the steady (``offset'') component, and the slope of the structure function -- can be used to probe the inner jet. The results are applied to the TeV blazar Mrk421, and this, within the context of the model, leads to the determination of several physical parameters: the ejection of a shell with average thickness of ~1E13 cm occurs on average every 10 minutes, and the shells collide ~1E17 cm away from the central source.Comment: 12 pages, 13 figures, to appear in Ap

    The Density Spike in Cosmic-Ray-Modified Shocks: Formation, Evolution, and Instability

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    We examine the formation and evolution of the density enhancement (density spike) that appears downstream of strong, cosmic-ray-modified shocks. This feature results from temporary overcompression of the flow by the combined cosmic-ray shock precursor/gas subshock. Formation of the density spike is expected whenever shock modification by cosmic-ray pressure increases strongly. That occurence may be anticipated for newly generated strong shocks or for cosmic-ray-modified shocks encountering a region of higher external density, for example. The predicted mass density within the spike increases with the shock Mach number and with shocks more dominated by cosmic-ray pressure. We find this spike to be linearly unstable under a modified Rayleigh-Taylor instability criterion at the early stage of its formation. We confirm this instability numerically using two independent codes based on the two-fluid model for cosmic-ray transport. These two-dimensional simulations show that the instability grows impulsively at early stages and then slows down as the gradients of total pressure and gas density decrease. Observational discovery of this unstable density spike behind shocks, possibly through radio emission enhanced by the amplified magnetic fields would provide evidence for the existence of strongly cosmic-ray modified shock structures.Comment: 26 pages in Latex and 6 figures. Accepted to Ap
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