1,721,199 research outputs found

    Statistical descriptions of nonlinear systems at the onset of chaos

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    Ensemble of initial conditions for nonlinear maps can be described in terms of entropy. This ensemble entropy shows an asymptotic linear growth with rate K. The rate K matches the logarithm of the corresponding asymptotic sensitivity to initial conditions l. The statistical formalism and the equality K 1⁄4 l can be extended to weakly chaotic systems by suitable and corresponding generalizations of the logarithm and of the entropy. Using the logistic map as a test case we consider a wide class of deformed statistical description which includes Tsallis, Abe and Kaniadakis proposals. The physical criterion of finite-entropy growth K strongly restricts the suitable entropies. We study how large is the region in parameter space where the generalized description is useful

    Helioseismology and Beryllium neutrinos

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    We derive a lower limit on the Beryllium neutrino flux on earth, Phi(Be)(min) = 1 . 10(9) cm(-2) s(-1), in the absence of oscillations, by using helioseismic data, the B-neutrino flux; measured by Superkamiokande and the hydrogen abundance at the solar center predicted by Standard Solar Model (SSM) calculations. We emphasize that this abundance is the only result of SSMs needed for getting Phi(Be)(min). We also derive lower bounds for the Gallium signal, G(min) = (91 +/- 3) SNU, and for the Chlorine signal, C(min) = (3.24 +/- 0.14) SNU, which are about 3 sigma above their corresponding experimental values, G(exp) = (72 +/- 6) SNU and C(exp) = (2.56 +/- 0.22) SNU. (C) 1999 Published by Elsevier Science B.V. All rights reserved
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