Lyapunov Exponents without Rescaling and Reorthogonalization

We present a new method for the computation of Lyapunov exponents utilizing representations of orthogonal matrices applied to decompositions of M or MM_trans where M is the tangent map. This method uses a minimal set of variables, does not require renormalization or reorthogonalization, can be used to efficiently compute partial Lyapunov spectra, and does not break down when the Lyapunov spectrum is degenerate.Comment: 4 pages, no figures, uses RevTeX plus macro (included). Phys. Rev. Lett. (in press

The Quantum-Classical Transition in Nonlinear Dynamical Systems

Viewed as approximations to quantum mechanics, classical evolutions can violate the positive-semidefiniteness of the density matrix. The nature of this violation suggests a classification of dynamical systems based on classical-quantum correspondence; we show that this can be used to identify when environmental interaction (decoherence) will be unsuccessful in inducing the quantum-classical transition. In particular, the late-time Wigner function can become positive without any corresponding approach to classical dynamics. In the light of these results, we emphasize key issues relevant for experiments studying the quantum-classical transition.Comment: 4 pages, multicol revtex (2 figures

Islamic religiosity, subjective well-being, and health

The aim of this paper is to explore the relationship between Islamic religiosity and satisfaction with a diverse range of life and health domains, in a sample of 2909 participants (1446 males, 1463 females) from Algeria. Factor analysis of the Islamic Religiosity Scale (IRS) indicates that it measures Religiosity as a multidimensional construct with two useful factors: Religious Practice and Religious Altruism. Religiosity at some level is ubiquitous through this sample, and it has a strong positive relationship with Subjective Well-Being (SWB). Moreover, this relationship is relatively unaffected by health deficiencies, even though such deficiencies generally have a negative influence on SWB scores. These findings are discussed in terms of the social context of Algeria.<br /