Generalized Fractal Kinetics in Complex Systems (Application to Biophysics and Biothechnology)

We derive a universal function for the kinetics of complex systems. This kinetic function unifies and generalizes previous theoretical attempts to describe what has been called "fractal kinetic".The concentration evolutionary equation is formally similar to the relaxation function obtained in the stochastic theory of relaxation, with two exponents a and n. The first one is due to memory effects and short-range correlations and the second one finds its origin in the long-range correlations and geometrical frustrations which give rise to ageing behavior. These effects can be formally handled by introducing adequate probability distributions for the rate coefficient. We show that the distribution of rate coefficients is the consequence of local variations of the free energy (energy landscape) appearing in the exponent of the Arrhenius formula. We discuss briefly the relation of the (n,a) kinetic formalism with the Tsallis theory of nonextensive systems.Comment: 15 pages, 3 figures, submitted to Physica

Vanishing Loss Effect on the Effective ac Conductivity behavior for 2D Composite Metal-Dielectric Films At The Percolation Threshold

We study the imaginary part of the effective $ac$ conductivity as well as its distribution probability for vanishing losses in 2D composites. This investigation showed that the effective medium theory provides only informations about the average conductivity, while its fluctuations which correspond to the field energy in this limit are neglected by this theory.Comment: 6 pages, 2 figures, submitted to Phys.Rev.

Local spin-susceptibility in disordered alloys II

We explore the analogy between a new formulation of the problem of local susceptibility in concentrated alloys and the theory of localization of electronic states in disordered systems. This discussion opens the way to a better description and understanding of the effect of local magnetic properties in disordered systems. In particular, the effect of cluster-cluster interactions and the nature of the magnetic-non magnetic phase transition in alloys is considered. Finally, we discuss the possibility in concentrated alloys of a cluster generalization of the spin glass phase