This group of investigators will study theoretical models of ionic movement in biological channels. The theoretical models will be used in conjunction with data, to suggest new experiments, and to modify the existing model. The goal of these models is to better understand the biology. Many functions of many cells are determined by individual channel proteins, which control the movement of substances and signals across otherwise quite impermeable membranes. This group will use the theory of Brownian motion of ions in solution to analyze the experimentally known properties of ion movement in channels. The group hopes to understand and predict the large mass of experimental data describing conductance, current-voltage relations, and selectivity of single open channels of various types.