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Considering epicyclic oscillations of pressure-supported perfect fluid tori orbiting Kerr black holes we examine non-geodesic (pressure) effects on the epicyclic modes properties. Using a perturbation method we derive fully general relativistic formulae for eigenfunctions and eigenfrequencies of the radial and vertical epicyclic modes of a slightly non-slender, constant specific angular momentum torus up to second-order accuracy with respect to the torus thickness. The behaviour of the axisymmetric and lowest-order (m = ±1) non-axisymmetric epicyclic modes is investigated. For an arbitrary black hole spin we find that, in comparison with the (axisymmetric) epicyclic frequencies of free test particles, non-slender tori receive negative pressure corrections and thus exhibit lower frequencies. Our findings are in qualitative agreement with the results of a recent pseudo-Newtonian study of the analogous problem defined within the Paczyński-Wiita potential. Implications of our results on the high-frequency quasi-periodic oscillation (QPO) models dealing with epicyclic oscillations are addressed.PACS numbers: 95.30.Lz, 95.30.Sf, 95.85.Nv, 97.60.Lf

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Zinc metal leaves grown two-dimensionally by electrodeposition were experimentally investigated with particular attention to the temperature dependence of their morphology. They changed form from a DLA-like to a disclike pattern with increasing temperature. The results of fractal analyses indicated that at temperatures lower than 20 C, their fractal dimension D is almost constant at 1.66, which is nearly equal to that of the two-dimensional DLA. At temperatures higher than 20 C, D increases almost linearly with temperature. From the analysis of scanning electron microscope images of various magnifications, it is shown that zinc metal leaves are fractals over a wide length range spanning five orders of magnitude with a single value of D. The relationship of the temperature-dependent change in the morphology of the metal leaves with variation of D has been successfully interpreted on the basis of Nittmann and Stanley's statistical mechanical model [J. Nittmann and H. E. Stanley: Nature 321 (1986) 663].