- Email: [email protected]
Memory of Prof. Ei Teramoto (1925–1996)
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Mathematical Biosciences 214 (2008) 3–5 www.elsevier.com/locate/mbs
In Memoriam
Memory of Prof. Ei Teramoto (1925–1996)
Ei Teramoto was the founder of the Japanese Society for Mathematical Biology and has been revered as the father of Mathematical Biology in Japan (Fig. 1). He dedicated himself to educating many young Japanese scientists, promoting international exchanges and playing a leading role in establishing mathematical biology in Japan. At the 10th anniversary of his death, I would like to provide a portrait of Ei Teramoto that I formed at close range as one of his early students. Ei Teramoto was born in 1925 in Matsue, an old town along the coast of the Sea of Japan (see Fig. 2, a picture painted by Teramoto). When entering high school, he moved to Kyoto, where he stayed for the rest of his life. He spent his university student days when Japan was fighting World War II, and it was a harsh time for the Japanese. He said he had to survive on food rations of two sweet potatoes a day. He graduated from the Department of Physics of Kyoto University in 1947, and then he immediately joined the faculty of Kyoto University, where he began his research career in statistical physics of chain polymers. In 1969, he moved to the newly founded department of Biophysics. There he started his research in mathematical biology. After retirement from Kyoto University, he continued to work in Ryukoku University for another 7 years. In 1996, Ei Teramoto passed away of liver cancer. His entire work covers an extensive area spanning physics and biology. Ei Teramoto’s first research subject was on the elasticity of high polymers. Unlike other common matters, materials like rubber increase in elasticity as the temperature rises; this is thought to be caused by the thermal motion of the chain polymers that make up these substances. To derive such fundamental properties of polymers using the methods of statistical mechanics, one needs to determine the mean-square end-to-end distance between chain polymers. In the past, this had been determined without taking into account the interaction between segments that form the polymer. But, in reality, two segments cannot exist in the same space at the same time. This observation led Teramoto to carry out a detailed analysis of the so-called excluded-volume effect. The excluded-volume effect can be
doi:10.1016/j.mbs.2008.01.003
explained within the context of a random-walk problem. In a random walk, where n flights take place, the meansquare distance is proportional to n. But if no flights are allowed to occur to places previously visited, how would this affect the mean-square distance? This problem is actually very difficult to solve, because the process is non-Markovian and we have to know the entire past history of the random walk. Since it was still before computers were available, Teramoto counted all the possible paths one by one, using pencil and paper to prove his theory. Later I heard from Teramoto himself that when he stacked the graph paper he used for the calculations, it had reached a height of 2 m. Teramoto presented his results at the 1953 International Conference on Theoretical Physics, which was the first conference held in post-war Japan inviting many prominent scientists from across the globe. Among the audience was Paul J. Flory (Nobel Laureate, 1974), who praised Teramoto’s work as an outstanding breakthrough in polymer physics. As a matter of fact, Flory himself had previously anticipated the existence of the excluded-volume effect, to which Teramoto gave a decisive proof. Later Ei Teramoto became interested in biomolecules like DNA and did studies on helix-coil transitions of DNA and in chemical-reaction kinetics. Meanwhile, he made great efforts to found a new department for biophysics in Kyoto University. In 1969, he moved from the Physics Department to this newly established department. His new office was famous for its ”Tatami” floor, which was probably the only one among all Japanese universities. Sitting on the tatami, he had an air of Samurai around him (see Fig. 1). Over the window of this room, one could see the panorama of Daimonji Hill that lies in East Kyoto. The seasonal changes taking place in the view of Daimonji Hill reminded Teramoto of the natural swings in animal and plant populations; and this perhaps led him to recognize mathematical ecology as a field where theoretical research would be quite effective, and could greatly contribute to human welfare in the future. On a worldwide scale, mathematical biology was still a relatively new field about to undergo a surge of new growth, but in Japan there
4
In Memoriam / Mathematical Biosciences 214 (2008) 3–5
Fig. 1. Ei Teramoto in his tatami-mat office.
were few researchers working in this field. Teramoto and his team entered this unexplored territory with enthusiasm. In the early 70s, Teramoto and his students started studies on the stability and structure of model ecosystems,
which later led to a number of fundamental contributions in population dynamics and ecosystem processes. A few representative studies among them are briefly introduced in the following. In 1978, Teramoto started a series of investigations on the switching effects of predation. He first dealt with a model of switching predation, where one predator feeds on two prey species. If the predation rates are constant, the system is described by the Lotka–Volterra equations, and it had been shown that one of the prey species always becomes extinct. However, Teramoto showed that if the predator preferentially attacks the more abundant prey species, the switching predator stabilizes the whole system, leading to coexistence of the three species. This was elegantly proven by introducing a Lyapunov function. Furthermore, he extended this model to the case where the two prey compete for a common resource. Again, he showed that a switching effect facilitates the coexistence of competing species. This series of papers were the first of their kind in demonstrating the effect of switching in the framework of population dynamics. Teramoto was also interested in biological diffusion. At the time, Professor Masaaki Morisita was on the faculty of Kyoto University, and he had done a pioneering work on population pressure by using ant lions. Teramoto and his team carefully examined Morisita’s empirical data and derived a non-linear diffusion equation, which generally describes animal dispersal under the influence of population pressure and environmental heterogeneity. They further extended this model to a system of two competing species, and showed that inter-specific population pressure leads to habitat segregation of the two species, even when they favor the same habitat. As a result, the two species
Fig. 2. The ruin of Matsue castle, painted by Ei Teramoto.
In Memoriam / Mathematical Biosciences 214 (2008) 3–5
are allowed to coexist though they mutually exclude one another in the absence of population pressure. In Ei Teramoto’s laboratory, there were people working in all types of mathematical biology. In addition to ecology, this ranged from neural networks to developmental pattern formation. More than 50 students in total came out of his laboratory. Many of them have been actively working at the front of mathematical biology. On top of these scientific achievements, he also contributed much to promote the development of mathematical biology in Japan. In 1989, Ei Teramoto and his colleague Masaya Yamaguti established the Japanese Association for Mathematical Biology (JAMB), which was intended to provide a forum to discuss mathematical biology in an informal and friendly atmosphere. Recently, this association was reorganized into a formal academic society, named the Japanese Society for Mathematical Biology (JSMB), in 2003. Ei Teramoto was also one of the founders of the Biophysical Society of Japan, and served as its president for two terms. From 1982 through 1985, he organized a large cooperative research program on sociobiology, which contributed to establishing evolutionary ecology in Japan. In 1990, he founded a fellowship for young scientists in mathematical biology, and supported travel expenses for participating in international conferences. He also performed a number of important administrative roles, including Dean of the Faculty of Science at Kyoto University. Teramoto energetically engaged himself in organizing international conferences. In 1978, 1985 and 1996, he convened the International Symposium on Mathematical Biology in Kyoto. For these conferences, close friends of Teramoto such as Simon Levin, Luigi Ricciardi, Akira Okubo and Lee Segel, among others, joined as organizers and help to invite many distinguished scientists worldwide. These events provided precious opportunities for young Japanese researchers to start exchanges on international stages. In addition to these conferences, Teramoto promoted International Joint Projects between Italy and Japan, and between the US and Japan, co-organized by Luigi Ricciardi and Donald DeAngelis, respectively. These led to very active exchanges of researchers and students from both sides.
5
Teramoto authored about a dozen books; the last one, entitled ”Mathematics of Random Phenomena,” includes his analyses of species-abundance relationships and the spatial structure of populations. A unique feature of the book is that each chapter contains a watercolor picture painted by Teramoto himself; some show the scenery of the promenade that leads from Kyoto University to his favorite pub. One such picture featured the bank of the River Kamo, along which young couples were sitting at even intervals, as though feeling population pressure at work among them. Ei Teramoto loved company and conversations over sake, and would often spend hours discussing science, philosophy and culture. He always related his stories with wit, which made people warm and relaxed. On special occasions, he would sing traditional Japanese love songs in a beautiful and heartfelt manner. He inspired many mathematical biologists of the younger generation. He will be remembered for his warm character, humorous talk, and his way of achieving important jobs in an entertaining way. Now it has been 10 years since he died. Meanwhile, the Japanese Society for Mathematical Biology he founded has been steadily growing, with a current membership of nearly 400. This August (2007), our Society had an international joint meeting with the Society for Mathematical Biology at San Jose in the United States, and last September (2006) we also held another international meeting in Kyushu, Japan, with the Korean Society for Mathematical Biology. In closing, I would like to express my deep gratitude to the organizers of BIOCOMP 2007, particularly, Chairman Prof. Luigi M. Ricciardi, for honoring Ei Teramoto by dedicating this conference to his memory and also providing me the opportunity of making this presentation. Nanako Shigesada * Faculty of Culture and Information Science, Doshisha University, 1-3 Miyakodani Tadara, Kyotanabe 610-0321, Japan E-mail address: [email protected] Received 28 November 2007; accepted 4 January 2008 Available online 18 January 2008
*
Tel.: +81 774 65 7676; fax: +81 774 65 7618.
Mathematical Biosciences 214 (2008) 3–5 www.elsevier.com/locate/mbs
In Memoriam
Memory of Prof. Ei Teramoto (1925–1996)
Ei Teramoto was the founder of the Japanese Society for Mathematical Biology and has been revered as the father of Mathematical Biology in Japan (Fig. 1). He dedicated himself to educating many young Japanese scientists, promoting international exchanges and playing a leading role in establishing mathematical biology in Japan. At the 10th anniversary of his death, I would like to provide a portrait of Ei Teramoto that I formed at close range as one of his early students. Ei Teramoto was born in 1925 in Matsue, an old town along the coast of the Sea of Japan (see Fig. 2, a picture painted by Teramoto). When entering high school, he moved to Kyoto, where he stayed for the rest of his life. He spent his university student days when Japan was fighting World War II, and it was a harsh time for the Japanese. He said he had to survive on food rations of two sweet potatoes a day. He graduated from the Department of Physics of Kyoto University in 1947, and then he immediately joined the faculty of Kyoto University, where he began his research career in statistical physics of chain polymers. In 1969, he moved to the newly founded department of Biophysics. There he started his research in mathematical biology. After retirement from Kyoto University, he continued to work in Ryukoku University for another 7 years. In 1996, Ei Teramoto passed away of liver cancer. His entire work covers an extensive area spanning physics and biology. Ei Teramoto’s first research subject was on the elasticity of high polymers. Unlike other common matters, materials like rubber increase in elasticity as the temperature rises; this is thought to be caused by the thermal motion of the chain polymers that make up these substances. To derive such fundamental properties of polymers using the methods of statistical mechanics, one needs to determine the mean-square end-to-end distance between chain polymers. In the past, this had been determined without taking into account the interaction between segments that form the polymer. But, in reality, two segments cannot exist in the same space at the same time. This observation led Teramoto to carry out a detailed analysis of the so-called excluded-volume effect. The excluded-volume effect can be
doi:10.1016/j.mbs.2008.01.003
explained within the context of a random-walk problem. In a random walk, where n flights take place, the meansquare distance is proportional to n. But if no flights are allowed to occur to places previously visited, how would this affect the mean-square distance? This problem is actually very difficult to solve, because the process is non-Markovian and we have to know the entire past history of the random walk. Since it was still before computers were available, Teramoto counted all the possible paths one by one, using pencil and paper to prove his theory. Later I heard from Teramoto himself that when he stacked the graph paper he used for the calculations, it had reached a height of 2 m. Teramoto presented his results at the 1953 International Conference on Theoretical Physics, which was the first conference held in post-war Japan inviting many prominent scientists from across the globe. Among the audience was Paul J. Flory (Nobel Laureate, 1974), who praised Teramoto’s work as an outstanding breakthrough in polymer physics. As a matter of fact, Flory himself had previously anticipated the existence of the excluded-volume effect, to which Teramoto gave a decisive proof. Later Ei Teramoto became interested in biomolecules like DNA and did studies on helix-coil transitions of DNA and in chemical-reaction kinetics. Meanwhile, he made great efforts to found a new department for biophysics in Kyoto University. In 1969, he moved from the Physics Department to this newly established department. His new office was famous for its ”Tatami” floor, which was probably the only one among all Japanese universities. Sitting on the tatami, he had an air of Samurai around him (see Fig. 1). Over the window of this room, one could see the panorama of Daimonji Hill that lies in East Kyoto. The seasonal changes taking place in the view of Daimonji Hill reminded Teramoto of the natural swings in animal and plant populations; and this perhaps led him to recognize mathematical ecology as a field where theoretical research would be quite effective, and could greatly contribute to human welfare in the future. On a worldwide scale, mathematical biology was still a relatively new field about to undergo a surge of new growth, but in Japan there
4
In Memoriam / Mathematical Biosciences 214 (2008) 3–5
Fig. 1. Ei Teramoto in his tatami-mat office.
were few researchers working in this field. Teramoto and his team entered this unexplored territory with enthusiasm. In the early 70s, Teramoto and his students started studies on the stability and structure of model ecosystems,
which later led to a number of fundamental contributions in population dynamics and ecosystem processes. A few representative studies among them are briefly introduced in the following. In 1978, Teramoto started a series of investigations on the switching effects of predation. He first dealt with a model of switching predation, where one predator feeds on two prey species. If the predation rates are constant, the system is described by the Lotka–Volterra equations, and it had been shown that one of the prey species always becomes extinct. However, Teramoto showed that if the predator preferentially attacks the more abundant prey species, the switching predator stabilizes the whole system, leading to coexistence of the three species. This was elegantly proven by introducing a Lyapunov function. Furthermore, he extended this model to the case where the two prey compete for a common resource. Again, he showed that a switching effect facilitates the coexistence of competing species. This series of papers were the first of their kind in demonstrating the effect of switching in the framework of population dynamics. Teramoto was also interested in biological diffusion. At the time, Professor Masaaki Morisita was on the faculty of Kyoto University, and he had done a pioneering work on population pressure by using ant lions. Teramoto and his team carefully examined Morisita’s empirical data and derived a non-linear diffusion equation, which generally describes animal dispersal under the influence of population pressure and environmental heterogeneity. They further extended this model to a system of two competing species, and showed that inter-specific population pressure leads to habitat segregation of the two species, even when they favor the same habitat. As a result, the two species
Fig. 2. The ruin of Matsue castle, painted by Ei Teramoto.
In Memoriam / Mathematical Biosciences 214 (2008) 3–5
are allowed to coexist though they mutually exclude one another in the absence of population pressure. In Ei Teramoto’s laboratory, there were people working in all types of mathematical biology. In addition to ecology, this ranged from neural networks to developmental pattern formation. More than 50 students in total came out of his laboratory. Many of them have been actively working at the front of mathematical biology. On top of these scientific achievements, he also contributed much to promote the development of mathematical biology in Japan. In 1989, Ei Teramoto and his colleague Masaya Yamaguti established the Japanese Association for Mathematical Biology (JAMB), which was intended to provide a forum to discuss mathematical biology in an informal and friendly atmosphere. Recently, this association was reorganized into a formal academic society, named the Japanese Society for Mathematical Biology (JSMB), in 2003. Ei Teramoto was also one of the founders of the Biophysical Society of Japan, and served as its president for two terms. From 1982 through 1985, he organized a large cooperative research program on sociobiology, which contributed to establishing evolutionary ecology in Japan. In 1990, he founded a fellowship for young scientists in mathematical biology, and supported travel expenses for participating in international conferences. He also performed a number of important administrative roles, including Dean of the Faculty of Science at Kyoto University. Teramoto energetically engaged himself in organizing international conferences. In 1978, 1985 and 1996, he convened the International Symposium on Mathematical Biology in Kyoto. For these conferences, close friends of Teramoto such as Simon Levin, Luigi Ricciardi, Akira Okubo and Lee Segel, among others, joined as organizers and help to invite many distinguished scientists worldwide. These events provided precious opportunities for young Japanese researchers to start exchanges on international stages. In addition to these conferences, Teramoto promoted International Joint Projects between Italy and Japan, and between the US and Japan, co-organized by Luigi Ricciardi and Donald DeAngelis, respectively. These led to very active exchanges of researchers and students from both sides.
5
Teramoto authored about a dozen books; the last one, entitled ”Mathematics of Random Phenomena,” includes his analyses of species-abundance relationships and the spatial structure of populations. A unique feature of the book is that each chapter contains a watercolor picture painted by Teramoto himself; some show the scenery of the promenade that leads from Kyoto University to his favorite pub. One such picture featured the bank of the River Kamo, along which young couples were sitting at even intervals, as though feeling population pressure at work among them. Ei Teramoto loved company and conversations over sake, and would often spend hours discussing science, philosophy and culture. He always related his stories with wit, which made people warm and relaxed. On special occasions, he would sing traditional Japanese love songs in a beautiful and heartfelt manner. He inspired many mathematical biologists of the younger generation. He will be remembered for his warm character, humorous talk, and his way of achieving important jobs in an entertaining way. Now it has been 10 years since he died. Meanwhile, the Japanese Society for Mathematical Biology he founded has been steadily growing, with a current membership of nearly 400. This August (2007), our Society had an international joint meeting with the Society for Mathematical Biology at San Jose in the United States, and last September (2006) we also held another international meeting in Kyushu, Japan, with the Korean Society for Mathematical Biology. In closing, I would like to express my deep gratitude to the organizers of BIOCOMP 2007, particularly, Chairman Prof. Luigi M. Ricciardi, for honoring Ei Teramoto by dedicating this conference to his memory and also providing me the opportunity of making this presentation. Nanako Shigesada * Faculty of Culture and Information Science, Doshisha University, 1-3 Miyakodani Tadara, Kyotanabe 610-0321, Japan E-mail address: [email protected] Received 28 November 2007; accepted 4 January 2008 Available online 18 January 2008
*
Tel.: +81 774 65 7676; fax: +81 774 65 7618.