Aplicação de dinâmica difusiva : peixes e portadores de carga

Abstract

In the present work, we investigate the diffusive dynamics in two types of natural systems, one biological and other physical-chemical. For the biological system, represented by a fish swimming in a circular arena (aquarium), we used a technique of data acquisition called tracking. With this approach, it was possible to analyze several aspects of fish movement as the preferred positions, angles, speeds, and periods of activity and inactivity. Through the temporal evolution of the fish mean square displacement, the dynamics was identified as superdiffusive. When compared with other animals, the results for one fish indicated differences and possible universalities. For the physical-chemical system, it was proposed an approximate mean square displacement obtained from the electrical conductivity, which considers the possibility of the presence of various types of charge carriers. By using this approach it was possible to make a connection with equivalent circuit models and, by means of electrical impedance spectroscopy measures, a few liquid samples were analyzed. This procedure allows to quantify several effects on the samples via the exponent of the temporal evolution of the approximate mean square displacement. In particular, in the samples analyzed, it was identified a subdiffusive dynamics. Due to the common anomalous diffusion feature in both systems, the achievements obtained here give support to possible models that assume the presence of this type of diffusion.