Photon-counting detectors are important to many areas of astronomy. A new generation, based on microchannel plate intensifiers, is already in use, and so understanding the fundamental problems of image-analysis techniques which are used by both current and new generation devices is necessary. We examine the "pattern noise" problem which causes modulation of the image. We find that it has a number of sources and suggest methods whereby it may be reduced. The problems discussed have applications to all fields (like CCD photometry and astrometry) which employ few-pixel, image-analysis techniques.
In this paper we study quark and lepton mass matrix textures in a model containing an additional U͑1͒ X gauge symmetry with origins in string compactification. The U͑1͒ X symmetry is broken near the string scale, and we assume that the anomalies are canceled by the Green-Schwarz mechanism. We also assume that fermion mass matrices are generated by an additional scalar field through an approach analogous to that of Froggatt and Nielsen. By requiring that supersymmetry not be broken at the high scale, we can derive the vacuum expectation value of this scalar field to then predict fermion masses and mixings for any given X charge assignment. We examine the possible solutions, and although in the simplest model they do not completely agree with experiment, the results are close enough to merit further inspection. ͓S0556-2821͑96͒00810-7͔
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