Donald S. Cohen, Charles Lee Powell Professor of Applied Mathematics, Emeritus, passed away on January 9, 2020, at the age of 85. Cohen was one of the first faculty members recruited for Caltech's newly formed applied mathematics program in 1965. He was named associate professor of applied mathematics in 1967 and earned tenure in 1971. His research covered a variety of topics, including early work in the theory of reaction-diffusion equations. His later research in nonlinear differential equations, pattern formation, stability, and bifurcations had a significant impact on mathematical biology and chemical engineering. Cohen was a popular teacher who received awards for undergraduate teaching excellence in 1979, 1987, and 1998; in 2000, he was awarded the Richard P. Feynman Prize for Excellence in Teaching. [Caltech story]
