Propagation of Waves of Chemical Activity in Stratified Media

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John Tyson is supported by a grant from the Theoretical and Computational Chemistry Program to perform theoretical studies of propagating waves of chemical activity in stratified media. In collaboration with Pavel K. Brazhnik, Tyson will study wave propagation in media with stratified inhomogeneities attempting to characterize the reflection and refraction of traveling waves at boundaries between layers. The study will be carried out by analytical, numerical, and experimental techniques. Analysis will be done by two complementary methods: the kinematic approach, and singular perturbation theory. Numerical simulation will also exploit complementary methods: standard finite-difference approximations to partial differential equations, and cellular automaton modeling of excitable media. The analytical and numerical results will be compared with experimental observations of wave propagation in a stratified chemical excitable medium, the Belousov-Zhabotinsky reaction. Traveling waves of chemical reaction are unusual but not uncommon occurrences in the natural world. Examples abound in combustion chemistry, catalytic converters, waves of membrane depolarization propagating through muscle tissue, waves of cyclic AMP production in slime mold growth, and a prominent Calcium wave signaling the fertilization of an egg by sperm. Chemical wave propagation has been studied for many years in homogeneous, isotropic media. Tyson's work would be the first attempt to study wave propagation in media with stratified inhomogeneities which are more realistic mimics of important biological systems.