9,422 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

    The rich cluster of galaxies ABCG~85. IV. Emission line galaxies, luminosity function and dynamical properties

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    This paper is the fourth of a series dealing with the cluster of galaxies ABCG 85. Using our two extensive photometric and spectroscopic catalogues (with 4232 and 551 galaxies respectively), we discuss here three topics derived from optical data. First, we present the properties of emission line versus non-emission line galaxies, showing that their spatial distributions somewhat differ; emission line galaxies tend to be more concentrated in the south region where groups appear to be falling onto the main cluster, in agreement with the hypothesis (presented in our previous paper) that this infall may create a shock which can heat the X-ray emitting gas and also enhance star formation in galaxies. Then, we analyze the luminosity function in the R band, which shows the presence of a dip similar to that observed in other clusters at comparable absolute magnitudes; this result is interpreted as due to comparable distributions of spirals, ellipticals and dwarfs in these various clusters. Finally, we present the dynamical analysis of the cluster using parametric and non-parametric methods and compare the dynamical mass profiles obtained from the X-ray and optical data.Comment: accepted for publication in A&

    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

    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

    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
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