Caltech Professor of Applied Mathematics, Emeritus, Donald S. Cohen, 1934-2020

Donald S. Cohen, Charles Lee Powell Professor of Applied Mathematics, Emeritus, passed away on January 9. He was 85 years old.

Cohen was one of the first faculty members recruited for Caltech’s newly formed applied mathematics program in 1965, starting as an assistant professor of mathematics. 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 (which are used to model systems with multiple interacting components, such as chemical reactions). His later research on nonlinear differential equations, pattern formation, stability, and bifurcations had a significant impact on mathematical biology and chemical engineering.

He formulated models that led to the development of quantitative studies of population dynamics in biological systems, using techniques that he was later able to adapt to analyzing the stability of chemical reaction systems. Later, he focused on mathematical models in the materials science of polymer films, studying how the properties of polymers could be tailored to control time release of pharmaceuticals.

Cohen earned a bachelor’s degree in physics from Brown University in 1956 and a master’s degree in mathematics from Cornell University in 1959 for his studies on probability and statistics. He earned a doctorate in applied mathematics from the Courant Institute at New York University in 1962.

At Caltech, he 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.

Cohen served as the executive officer of applied mathematics from 1988 to 1993, and chair of the Division of Engineering and Applied Science in 1990. He also served as chairman of the faculty from 1983 to 1985, and from 1986 to 1987 he chaired the faculty advisory committee of the Caltech Board of Trustees to select Caltech’s fifth president. In 1998, he was named Charles Lee Powell Professor of Applied Mathematics. He retired in 2003.

Beyond Caltech, Cohen served on numerous national committees, including the Society for Industrial and Applied Mathematics, the American Mathematical Society, and the American Association for the Advancement of Science. From 1993 to 1995, he served as the director of the Center for Nonlinear Studies at Los Alamos National Laboratory.

A full obituary will be published at a later date.