George Sell passed away on Friday, May 29. He was born on February 7, 1937, in Milwaukee, Wisconsin, and grew up in the Milwaukee suburb of Hales Corners. He was the oldest of eight children. Two of his siblings died in infancy, so he grew up with four brothers and a sister. In high school, he had the good fortune of teachers who sparked his interest in mathematics and encouraged him to pursue the subject further. With a scholarship from General Electric, where his father worked, he attended Marquette University. It was there in 1955 that he met his wife, Geraldine, and three years later they married.
From Marquette, he went to the University of Michigan for a Ph.D., where he was jointly advised by Wilfred Kaplan and Lamberto Cesari. His thesis was awarded the Sumner B. Myers Prize for the year's best dissertation in mathematics. In addition to his graduate studies, he held a recurring summer job working at AC Sparkplug on the guidance system for the Titan rockets of the nascent space program. During this time, his four oldest children were born. After finishing graduate school in 1962, George spent two years at Harvard University as a Benjamin Pierce Instructor before accepting an assistant professor position at the University of Minnesota. His two youngest children were born during his tenure there. He was promoted to Associate Professor in 1968 after spending the previous year at the University of Southern California, and then served as Full Professor in 1973 until his death. In addition to his service on the faculty of the university, he served as the Director of Undergraduate Studies in 1969-70, as Associate Head of the School of Mathematics in 1970-71.
In 1977-78, George spent a year as Program Director in Classical Analysis at the National Science Foundation (NSF). In the early 1980's he, Willard Miller, Jr., then Department Head, and Hans Weinberger answered the National Science Foundation's call for proposals for a new national mathematics research institute. Their proposal, for Institute for Mathematics and Its Applications, that emphasized the novel idea (for the time) of seriously connecting mathematics with its wide range of applications, in research, in industry, and in government labs, that the NSF decided to fund two Math Institutes, and so the IMA began operations in 1982, continuing to this day. George served as its first Associate Director from 1982 to 1987. Over its many years of existence the IMA has had a profound and wide ranging impact on mathematics, its applications, and the many thousands of researchers who visited, organized programs, served as postdocs, etc. Later, from 1984-94, he served as the first Director of the Army High Performance Computing Research Center at the University of Minnesota.
George devoted the majority of his professional life to the study of differential equations, dynamical systems, and their applications to fluid dynamics, climate modeling, control systems, and elsewhere. Although he held sabbatical appointments at various institutions, he always returned to Minnesota to continue his work. He is the author or coauthor of over 120 research publications in these areas, as well as 5 highly popular books covering dynamics and differential equations. In 1990, George was awarded an honorary doctorate by Leningrad State University in the Soviet Union, just the second foreigner to be so honored by that institution. He supervised 16 Ph.D. students, many of whom went on to successful academic research careers of their own, as well as a large number of postdocs in both the School of Mathematics and the IMA. In 1988, he became the founding editor in chief of the very successful Journal of Dynamics and Differential Equations, and continued to serve in this capacity of managing editor until his death.
Those who knew George will remember him as a kind, loving, and generous person. He enjoyed good food and drink, travel, history, Paris, and the Green Bay Packers. Most importantly, though, he enjoyed simply being in the company of his family and friends. George is predeceased by his parents, George and Alice, and two brothers, Robert and Harvey (a.k.a. Luke). He is survived by siblings, William, David, and Susan; his loving wife and lifetime companion, Geraldine; his children, George (and Christine), Mark (and Penny), Marie, Paula (and Timothy), Thomas (and Dana), and Eric; and by his grandchildren, Meryl, Claire, Erin, Bethany, Matthew, and Annika.
A meeting in George's memory is being planned by the School of Mathematics and the IMA. Details and links will appear soon.