Theoretical analysis of the optomechanics of degenerate bosonic atoms with a single feedback mirror shows that self-structuring occurs only above an input threshold that is quantum mechanical in origin. This threshold also implies a lower limit to the size (period) of patterns that can be produced in a condensate for a given pump intensity. These thresholds are interpreted as due to the quantum...

A method for analyzing a N-component percolation model in terms of one parameter p1 is presented. In Monte Carlo simulations on 16, 32, 64, and 128 simple cubic lattices the percolation threshold p1 c is determined for N52. Continuous transitions of p1 c are reported in two limits for the bond existence probabilities p5 and pÞ . In the same limits, empirical formulas for the percolation thresho...

We probe the geometry around an elementary BPS (EBPS) state in heterotic string theory compactified on a six-torus by scattering a massless scalar off it and comparing with the corresponding experiment in which the EBPS state is replaced by a classical extremal black hole background satisfying the BPS condition. We find that the low energy limit of the scattering amplitudes precisely agree if o...

We discuss how threshold mechanisms can be effectively employed to control chaotic systems onto stable fixed points and limit cycles of widely varying periodicities. Then, we outline the theory and experimental realization of fundamental logic-gates from a chaotic system, using thresholding to effect control. A key feature of this implementation is that a single chaotic 'processor' can be flexi...

Extreme precipitation events have significant environmental consequences because they may cause considerable damages to urban as well as rural areas. The aim of this work is to construct a threshold model which will describe the exceedances over a threshold for the daily precipitation totals over Athens, Greece. The data used are daily precipitation totals recorded at the National Observatory o...

We develop an analytical approach to the susceptible-infected-susceptible epidemic model that allows us to unravel the true origin of the absence of an epidemic threshold in heterogeneous networks. We find that a delicate balance between the number of high degree nodes in the network and the topological distance between them dictates the existence or absence of such a threshold. In particular, ...

We describe evidence consistent with the proposal that the visual system contains a parallel array of size-tuned mechanisms sensitive to orientation texture-defined (OTD) form, and propose that the relative activity of these mechanisms determines spatial frequency discrimination threshold for OTD gratings. Using a pattern of short lines we measured spatial frequency discrimination thresholds fo...