Scroll rings stable

We see that a simple phenomenological model (l)-(2) is able to reproduce a large number of dynamical effects observed in the experiments and in the numerical simulations of the reaction-diffusion models of weakly excitable media. Its modifications can be used to describe the respective phenomena in the anisotropic media as well as the wave propagation over the curved surfaces. A similar model is formulated for the weakly excitable three-dimensional media. It explains a transition from the collapse to expansion of the scroll rings and shows the existence of stable scroll rings. 

---