Download or read book Noise-sustained Oscillation and Synchronization of Excitable Media with Stirring written by and published by . This book was released on 2004 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt: Constructive effects of noise have been well studied in spatially extended systems. In most of these studies, the media are static, reaction-diffusion type, and the constructive effects are a consequence of the interplay between local excitation due to noise perturbation and propagation of excitation due to diffusion. Many chemical or biological processes occur in a fluid environment with mixing. In this paper, we investigate the interplay among noise, excitability, diffusion and mixing in excitable media advected by a chaotic flow, in a 2-d Fitz Hugh-Nagumo model described by the reaction-advection-diffusion equations. Without stirring, noise can only generate non-coherent excited patches of the static media. In the presence of stirring, we can observe three dynamical and pattern formation regimes: (i) Non-coherent excitation, when mixing is not strong enough to achieve synchronization of independent excitations developed at different locations; (ii) Coherent global excitation, when noise-perturbation survives the mixing to generate a synchronized excitation of the whole domain; and (iii) Homogenization, when strong enough stirring dilutes quickly those noise-induced local excitations. In the presence of an external sub-threshold periodic forcing, the period of-the noise-sustained oscillations can be locked by the forcing period with different ratios. Our results may be verified in experiments and find applications in population dynamics of oceanic ecological systems.