Obituary: Masayasu Mimura

By Yasumasa Nishiura

It is with great sadness that I acknowledge the recent passing of Masayasu Mimura, a world-renowned expert in the field of mathematical biology, on April 8, 2021. He was 79 years old. Masayasu—known by friends and colleagues as Mayan—was president of the Japan Society for Industrial and Applied Mathematics from 2002 to 2003 and president of the Japanese Society for Mathematical Biology from 2013 to 2014.

Mayan was born in Takamatsu, Japan in 1941 and spent his youth there. He studied at Kyoto University, earning an M.S. in applied mathematics and physics in 1967 and a Ph.D. in 1973 (under the guidance of Masaya Yamaguti). Every Saturday, Yamaguti organized a seminar in his office that inspired open-minded discussion about a wide spectrum of hot topics in mathematics, biology, and even economics. Mayan was a most active discussant.

Upon receiving his Ph.D., Mayan immediately joined the faculty at Konan University. A defining point in his career was his 1976 visit with James D. Murray at Oxford University. I clearly remember how Mayan established confidence in the exploration of mathematical biology, particularly through modeling and computation. He always made sure to ensure rigor in the various aspects of his research and even started to apply asymptotic analysis techniques to many problems in the late 1970s.

Mayan became a professor at Konan in 1979 and then received a professorship at Hiroshima University the following year. Many mathematics researchers in the 1980s sought to utilize the singular perturbation technique to show the existence and stability of the pulse waves that arise in the Hodgkin-Huxley equations. Mayan presented an invited talk on patterns of reaction diffusion systems at the International Congress of Mathematicians in 1990 and the International Congress for Industrial and Applied Mathematics in 1991. 

Mayan remained dedicated to establishing a center for mathematical biology in Hiroshima, although he moved to the University of Tokyo in 1993. His vision for Hiroshima University was eventually realized with the establishment of the Department of Mathematical and Life Sciences in 1999, which triggered his return to the university that same year. In 2004, Mayan accepted a position at Meiji University. Thanks in large part to his enormous efforts, the university opened the Meiji Institute for Advanced Study of Mathematical Sciences (MIMS) in 2007. Since 2020, MIMS has actively worked as a Ministry of Education, Culture, Sports, Science, and Technology Joint Usage/Research Center. Mayan was also a founding member of the French-Japanese Reaction-Diffusion Laboratory (ReaDiLab) and the France-Japan-Korea-Taiwan Reaction-Diffusion Network (ReaDiNet) International Research Network, where he made tremendous efforts to unite scientists from all four countries. 

Friends and acquaintances remember Mayan as impressively energetic and ambitious, even in his later years. He was endlessly curious, taking delight in unique and unconventional approaches to biological problems. In particular, he maintained a lifelong interest in bacterial colony patterns and competitive diffusion systems, for which he enjoyed the process of mathematical modeling. Students, postdoctoral researchers, and colleagues were extremely important throughout Mayan’s life; in fact, he authored manuscripts with more than 120 different researchers from around the world. He will be deeply missed in our community, but both his memory and work will continue to inspire even greater achievements. 

Mayan passed away with his beloved wife, Yoko Mimura, by his side. He was ranked as Junior Fourth Rank and awarded The Order of the Sacred Treasure, Gold Rays with Neck Ribbon on the day of his passing.

Acknowledgments: The author thanks Elliott Ginder, Hideo Ikeda, Tom Mitsui, Toshi Ogawa, Hisashi Okamoto, and Shigetoshi Yazaki for their valuable input.

Yasumasa Nishiura is a professor emeritus at Hokkaido University, visiting professor at Chubu University, and research advisor at Tohoku University’s Advanced Institute for Materials Research.