82,391 research outputs found

    Peer observation : a tool for continuing professional development

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    Peer observation has been advocated as a means of monitoring and improving the quality of teaching within Higher Education, whilst peer support and review have been used to provide feedback and monitoring within the clinical context. The process of peer observation of practice within educational, managerial and clinical settings could facilitate improvements in all aspects of practice, have relevance as a tool for continuing professional development (CPD) and help improve the quality of care for service users. This article presents the background and relevance of peer observation to health care professionals, suggests a process that can be implemented and considers relevant contextual issues. Finally it suggests that peer observation has potential benefits for all areas and levels of health care practice

    Energy-momentum balance in quantum dielectrics

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    We calculate the energy-momentum balance in quantum dielectrics such as Bose-Einstein condensates. In agreement with the experiment [G. K. Campbell et al. Phys. Rev. Lett. 94, 170403 (2005)] variations of the Minkowski momentum are imprinted onto the phase, whereas the Abraham tensor drives the flow of the dielectric. Our analysis indicates that the Abraham-Minkowski controversy has its root in the Roentgen interaction of the electromagnetic field in dielectric media

    Recent direct measurement of the Top quark mass and quasi-infrared fixed point

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    We note that the recent direct measurement of the top quark mass at 173.3±5.6(stat)±6.2(syst)173.3 \pm 5.6 (stat) \pm 6.2 (syst) by D0 collaboration severely constrains the theoretically attractive infra-red fixed point scenario of the top quark Yukawa coupling in supersymmetric GUTs. For one-step unified models the above mentioned measurement bounds the arbitrary but experimentally determinable parameter tanβ\tan \beta to the range 1.3tanβ2.11.3 \le \tan \beta \le 2.1. Further crunch on the top quark mass may determine tanβ\tan \beta even more accurately within the fixed point scenario. On the other hand an experimental value of tanβ>2.1\tan \beta > 2.1 will rule out the fixed point scenario bounding ht2(MX)/4πh^2_t(M_X)/4 \pi to 0.022 from above.Comment: 7 pages, Latex with epsf style, 1 figure, captions.st

    Deducing radiation pressure on a submerged mirror from the Doppler shift

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    Radiation pressure on a flat mirror submerged in a transparent liquid, depends not only on the refractive index n of the liquid, but also on the phase angle psi_0 of the Fresnel reflection coefficient of the mirror, which could be anywhere between 0^{\circ} and 180^{\circ}. Depending on the value of psi_0, the momentum per incident photon picked up by the mirror covers the range between the Abraham and Minkowski values, i.e., the interval (2\hbarw_0/nc,2n\hbarw_0/c). Here \hbar is the reduced Planck constant, w_0 is the frequency of the incident photon, and c is the speed of light in vacuum. We argue that a simple experimental setup involving a dielectric slab of refractive index n, a vibrating mirror placed a short distance behind the slab, a collimated, monochromatic light beam illuminating the mirror through the slab, and an interferometer to measure the phase of the reflected beam, is all that is needed to deduce the precise magnitude of the radiation pressure on a submerged mirror. In the proposed experiment, the transparent slab plays the role of the submerging liquid (even though it remains detached from the mirror at all times), and the adjustable gap between the mirror and the slab simulates the variable phase-angle psi_0. The phase of the reflected beam, measured as a function of time during one oscillation period of the mirror, then provides the information needed to determine the gap-dependence of the reflected beam's Doppler shift and, consequently, the radiation pressure experienced by the mirror.Comment: 9 pages, 2 figures, 13 equation

    On the Origin of X-ray Emission From Millisecond Pulsars in 47 Tuc

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    The observed spectra and X-ray luminosities of millisecond pulsars in 47 Tuc can be interpreted in the context of theoretical models based on strong, small scale multipole fields on the neutron star surface. For multipole fields that are relatively strong as compared to the large scale dipole field, the emitted X-rays are thermal and likely result from polar cap heating associated with the return current from the polar gap. On the other hand, for weak multipole fields, the emission is nonthermal and results from synchrotron radiation of e±e^{\pm} pairs created by curvature radiation. The X-ray luminosity, LxL_x, is related to the spin down power, LsdL_{sd}, expressed in the form LxLsdβL_x \propto L^{\beta}_{sd} with β0.5\beta \sim 0.5 and 1\sim 1 for strong and weak multipole fields respectively. If the polar cap size is of the order of the length scale of the multipole field, ss and β0.5\beta \sim 0.5, the polar cap temperature is 3×106K(Lsd1034ergs1)1/8(s3×104cm)1/2\sim 3 \times 10^6 K (\frac{L_{sd}}{10^{34}erg s^{-1}})^{1/8} (\frac{s}{3\times 10^4 cm})^{-1/2}. A comparison of the X-ray properties of millisecond pulsars in globular clusters and in the Galactic field suggests that the emergence of relatively strong small scale multipole fields from the neutron star interior may be correlated with the age and evolutionary history of the underlying neutron star.Comment: 25 pages, 2 figures, accepted for publication in Ap

    Stochastic models for atomic clocks

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    For the atomic clocks used in the National Bureau of Standards Time Scales, an adequate model is the superposition of white FM, random walk FM, and linear frequency drift for times longer than about one minute. The model was tested on several clocks using maximum likelihood techniques for parameter estimation and the residuals were acceptably random. Conventional diagnostics indicate that additional model elements contribute no significant improvement to the model even at the expense of the added model complexity
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