Professor Dr. Yongwimon Lenbury Thailand Outstanding Scientist Award (Mathematics) Year 2007

The Achievements of Professor Dr. Yongwimon Lenbury

Professor Dr. Yongwimon Lenbury was born in Bangkok on August 23, 1952. Following primary and secondary education in Thailand, she went abroad to study under the Columbo Plan Scholarship and received a B.Sc. and an M.Sc. in Applied Mathematics from the Australian National University. She later received a Ph.D. in Mathematics from Vanderbilt University in the United States of America and returned to the Department of Mathematics, Faculty of Science, Mahidol University to teach, conduct research in dynamical modeling of nonlinear systems in biology and medicine, and guide students at both the undergraduate and graduate levels. She was appointed professor of mathematics in 1996.

From her research contributions, she was meritoriously given the Outstanding Researcher Award in the field of Physical Science and Mathematics from the National Research Council in 1998.

Professor Lenbury's research interest is in the construction and analysis of mathematical models of systems in biology and medical science, using theory of nonlinear and dynamical systems. Her research has yielded over 60 international journal publications, and may be grouped into 3 areas of interest.

The first area is concerned with dynamical modeling of nonlinear systems in biotechnology. Consideration was given to the effects of different important external factors on the effcient operation of continuous bioreactors, such as the effect of products of a fermentation system on the rates of change of cells and limiting substrate, or the effect of membrane permeability on the transfer of nutrient across the cell membrane, due to geometric field variation, for example. The results of such research work on dynamical modeling can be extremely useful for the optimal control and management of such systems of crucial importance in the pharmaceutical and food industries.

The second area involves the dynamical modeling of nonlinear systems in the field of medical science. Professor Lenbury and her research team have been interested in modeling the cortisol secretion as well as testosterone secretion cascade systems in the human body, modeling the control of plasma glucose by insulin secreted by the pancreatic ß-cells, and modeling the roles of estrogen and parathyroid hormones on bone resorption, for example.

Lately, Professor Lenbury has produced research results on the analysis of models for signal transduction processes among living cells, which has important implications on the study of how different processes in the human body function or disfunction. Professor Lenbury and her team collaborate actively with medical experts such as a heart surgeon who routinely carries out coronary bypass operations on patients with atherosclerosis. She would like to advice on how the operation should be carried out for optimal and long lasting result. This needs mathematical modeling and numerical computation to simulate blood flow in stenosed blood vessels using real geometry. Moreover, Professor Lenbury and her team have studied models of several epidemics which create serious control problems, such as HIV, malaria, parasitic infection, and drug resistance.

The third area of her research interest is on the dynamical modeling of nonlinear systems in ecology and environmental science. Extending from the basic population model and that of a predator-prey system, several important factors were incorporated to discover their impacts, such as the impact toxic substances in the environment, impact of migration, that of parasitic infection, or that of delays in reproduction rate, on the stability of the system or survival of the species. This type of research provides valuable information for decision or public policy makers who set regulations and laws on the management and conservation of the environment in parallel with economic and industrial growth of this nation.

All the above research work involves discovering and utilizing novel methodologies for the analysis of complicated model systems, such as nonlinear system theory, singular perturbation theory, bifurcation theory, computational techniques, control theory, knots theory, fixed point theory, incorporation of time delays and stochastic processes, which have to be applied to appropritate model systems under study. Such research work, apart from allowing us to better understand the systems of interest, also enhances our ability to diagnose, control and make life saving treatment decisions. Professor Lenbury's work is thus multidisciplinary in nature that needs participation of researchers from several overlapping fields. Her research team involves mathematicians, physicists, physiologists and medical scientists from several institutions both in Thailand and abroad. Apart form those from various departments at Mahidol University, her team includes researchers from Chiang Mai University, Thammasat University, King Mongkut's Institute of Technology North Bangkok, Burapha University, Bangkok Heart Hospital, Silpakorn University, Vanderbit University, CNR IASI Laboratorio di Biomatematica in ltaly, and so on. Her effort has yielded over 60 publications in international journals, some of which are in the Science Direct's lists of top 25 hottest articles in the respective journals.