7,823 research outputs found

    Weak values and the quantum phase space

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    We address the issue of how to properly treat, and in a more general setting, the concept of a weak value of a weak measurement in quantum mechanics. We show that for this purpose, one must take in account the effects of the measuring process on the entire phase space of the measuring system. By using coherent states, we go a step further than Jozsa in a recent paper, and we present an example where the result of the measurement is symmetrical in the position and momentum observables and seems to be much better suited for quantum optical implementation.Comment: 07 pages, accepted for PR

    Errors on the inverse problem solution for a noisy spherical gravitational wave antenna

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    A single spherical antenna is capable of measuring the direction and polarization of a gravitational wave. It is possible to solve the inverse problem using only linear algebra even in the presence of noise. The simplicity of this solution enables one to explore the error on the solution using standard techniques. In this paper we derive the error on the direction and polarization measurements of a gravitational wave. We show that the solid angle error and the uncertainty on the wave amplitude are direction independent. We also discuss the possibility of determining the polarization amplitudes with isotropic sensitivity for any given gravitational wave source.Comment: 13 pages, 4 figures, LaTeX2e, IOP style, submitted to CQ

    A catalogue of velocities in the cluster of galaxies Abell 85

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    We present a catalogue of velocities for 551 galaxies (and give the coordinates of 39 stars misclassified as galaxies in our photometric plate catalogue) in a region covering about 100'×\times100' (0.94×\times0.94 Mpc for an average redshift of 0.0555, assuming H∘_\circ=50 km s−1^{-1} Mpc−1^{-1}) in the direction of the rich cluster Abell 85. This catalogue includes previously published redshifts by Beers et al. (1991) and Malumuth et al. (1992), together with our 367 new measurements. A total of 305 galaxies have velocities in the interval 13350-20000 km s−1^{-1}, and will be considered as members of the cluster. Abell 85 therefore becomes one of the clusters with the highest number of measured redshifts; its optical properties are being investigated in a companion paper.Comment: Accepted for publication in A&AS, Table 4 available in electronic form onl

    Pseudophakic Cystoid Macular Edema

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    Cataract surgery is an efficient procedure, and is generally associated with good visual results. Nevertheless, cystoid macular edema (CME) may develop, and this can result in suboptimal postoperative vision. Many factors are considered to contribute to its development, and although the treatment options depend upon the underlying cause of CME, the usual therapeutic approach for prophylaxis and treatment of CME is directed towards blocking the inflammatory mediators. This article provides a review of possible risk factors, pathogeneses, incidence rates, and methods of diagnosis, as well as the current guidelines for managing CM

    Stable Gravastars of Anisotropic Dark Energy

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    Dynamical models of prototype gravastars made of phantom energy are constructed, in which an infinitely thin spherical shell of a perfect fluid with the equation of state p=(1−γ)σp = (1-\gamma)\sigma divides the whole spacetime into two regions, the internal region filled with a dark energy (or phantom) fluid, and the external Schwarzschild region. It is found that in some cases the models represent the "bounded excursion" stable gravastars, where the thin shell is oscillating between two finite radii, while in other cases they collapse until the formation of black holes or normal stars. In the phase space, the region for the "bounded excursion" gravastars is very small in comparison to that of black holes, but not empty, as found in our previous papers. Therefore, although the existence of gravastars can not be completely excluded from current analysis, the opposite is not possible either, that is, even if gravastars exist, they do not exclude the existence of black holes.Comment: 35 pages, 43 figures, added some clarifying texts and corrected some typos, accepted for publication in JCA
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