The University of Tokyo · Environmental Science
Professor Osamu Saitô's research lab specializes in polymer chemistry and radiation-induced reactions, focusing on the theoretical modeling of molecular weight distributions in irradiated polymers. The lab investigates complex processes such as cross-linking, cyclization, branching, and degradation, with particular attention to gelation kinetics and the role of end-linking probabilities. Additionally, the lab contributes to interdisciplinary studies in historical demography and urban-rural development, particularly in Sub-Saharan Africa and Japan, integrating quantitative methods with social science research. The work bridges physical chemistry with societal and demographic challenges through rigorous analytical and modeling approaches.
Figures are computed from collected data and may differ slightly.
Integro-differential equations are obtained, which describe the variation of molecular weight distributions in a polymer substance caused by irradiation. The solutions of these equations give the gel point and the average molecular weights. In the case of cross-linking without cyclization, the results agree with those obtained by other authors. The problems involving cyclization and branching are also solved, showing that the gel formation is retarded by cyclization and that the weight average b
Urban-rural linkages are an integral part of fostering development in both urban and rural communities. However, the focus on development tends to have an urban bias toward Sub-Saharan Africa (SSA) with an increase in urbanization. Ghana is one of the fastest urbanizing countries in SSA. This paper sought to identify the challenges of urban-rural linkages, their corresponding solutions, and contributions to Agenda 2030 that are context-specific to Ghana through a stepwise solution scanning techn
Activation of TLR4 induces tactile allodynia, which is probably mediated by TNF released by activated spinal glia.
The effect of end-linking induced in polymers by high energy radiation is discussed. When cyclization does not occur, the same results are obtained as those derived by A. Charlesby, and moreover it is known that for any initial distribution the gel formation does not occur when σ is smaller than 1/4, where σ represents the probability that an end produced by a molecular scission links with a monomer unit of another molecule. The theory also gives the average molecular weights and the average end
Historical demography as a separate discipline came into existence when family reconstruction was first developed for the analysis of a pre-transition population. This paper assesses the significant achievements made in this field of population studies since then. Attention is also paid to equally significant findings obtained from aggregative analysis based on back projection, and to a large body of research results for the period of the demographic transition. In the last part of the paper, ne
(1992). Infanticide, fertility and ‘population stagnation’: The state of Tokugawa historical demography. Japan Forum: Vol. 4, No. 2, pp. 369-381.
The advent of modern technology in agriculture has increased the efficiency of our food production but also poses pressures on the sustainability of our planet. The Globally Important Agricultural Heritage Systems (GIAHS) of the Food and Agriculture Organization of the United Nations (FAO) has been developed to safeguard traditional agricultural systems of global importance, which harnesses the harmonious relationship between people and nature. First launched in the World Summit on Sustainable D
Faced with a lack of fine grain data availability, in rapidly emerging urban centers of developing nations, the study explored a mapping methodology to create thematic map of public urban green space (UGS). Using GIS, a thematic map of Nagpur city, India was prepared. The objective was to prepare spatial data that are relevant for planners and policy makers, with detailed UGS typologies and to update the status of overall availability and distribution of hierarchical recreational green spaces in
Computer calculations of the fraction of gel as a function of radiation dose have enabled tables to be constructed of the relation between gel fraction and number of crosslinks for various initial weight to number average molecular weight ratios and for a number of different ratios of chain scissions to crosslinks. The theory is based on the Wesslau molecular-weight distribution function and the results are in much better agreement in the case of many polymers than are the theoretical calculatio
This paper relates to on-line security assessment and determination of optimal preventive measures of power system, which the authors have developed by using two methods, digital and digital-analog hybrid. The description includes the power system of the Tokyo Electric Power Co., Inc. (TEPCO) for the security assessment; the software configuration for the on-line security assessment; fast calculating methods for the assessment, with emphasis on the study of transient stability; methods for deter
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