Chemically-reacting systems tend to organize themselves in space and time, unless the usual agents of mass and energy transfer among volume elements (e.g. diffusion, convection, radiation) are suppressed. An instance simple enough to be fruitfully tractable in both theory and experiment has come to light in an aqueous isothermal reaction system internally coupled by molecular diffusion alone. Mathematical analysis, computer simulation, and chemical experiments have revealed the existence of mm-scale "organizing centers" in such excitable reaction systems. Dr. Winfree plans to study the anatomy and behavior of such organizing centers experimentally and by computer simulation. Such systems are of interest not only to physical chemists, engineers, and mathematicians, but also to biophysicists studying the activity patterns in neuromuscular tissue, i.e. fibrillations, cardiac rhythms and arrhythmias, and epileptic seizures. For example, recent experimental tests of Dr. Winfree's proposition that the newly discovered three-dimensional waves in reaction-diffusion media should also be observed in heart muscle, where the equations are practically the same even though the underlying physics is quite different, indicate that the proposition is sound. These results are of immediate practical interest to cardiologists.
