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Tuning curves for stimulus disparity were constructed for units in area 18 and along the 17/18 border of the cat visual cortex (N = 248). Units were activated with stimuli moving in the same (in-phase motion) or in the opposite direction (antiphase motion) across the two retinae. Over 70% of the units encountered showed sensitivity to stimulus disparity. A… (More)
We extend the three dimensional stringy black hole of Horne and Horowitz to four dimensions. After a brief discussion of the global properties of the metric, we discuss the stability of the background with respect to small perturbations, following the methods of Gilbert and of Chandrasekhar. The potential for axial perturbations is found to be positive… (More)
Cosmological solutions of the beta function equations for the background fields of the closed bosonic string are investigated at the one-loop level. Following recent workthe of Kostelecky and Perry, it is assumed that the spatial sections of the space-time are conformally flat. Working in the sigma-model frame, the non-trivial tachyon potential is utilized… (More)
We consider solutions of the field equations for the large N dilaton gravity model in 1 + 1 dimensions of Callan, Giddings, Harvey, and Strominger (CGHS). We find time dependant solutions in the weak coupling region with finite mass and vanishing flux, as well as solutions with lie entirely in the Liouville region.
A comprehensive analysis of small fluctuations about two–dimensional string–theoretic and string–inspired black holes is presented. It is shown with specific examples that two–dimensional black holes behave in a radically different way from all known black holes in four dimensions. For both the SL(2, R)/U(1) black hole and the two–dimensional black hole… (More)