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Car- and ride-sharing services are focused on environmental and new business issues in recent years. This study analyzes environmental effects of the transition from car ownership to sharing services and aims to clarify sensitive parameters by sensitivity analysis. The following steps are carried out: 1) model causal relationships between variables in ownership and sharing service business models, 2) develop life cycle simulation models of gasoline and electric vehicles based on these causal relationships, and 3) analyze transition scenarios. The results show that carbon dioxide emissions and copper usage decrease with the diffusion of car- and ride-sharing services, and that the average number of vehicle passengers is the most sensitive parameter for car- and ride-sharing services.

We have demonstrated new and efficient electron transporting (ET) and hole blocking (HB) materials for organic light-emitting devices (OLEDs). The bipyridyl-substituted oxadiazole derivatives can form a stable glassy state with glass transition temperatures greater than 100 °C. The bipyridyl-substituted oxadiazole derivatives have excellent ET, HB and electron accepting ability and also exhibit electrical operation durability. Bipyridyl-substituted oxadiazoles are a promising candidate for ET and HB materials for OLEDs.

In post-World War II Japan, rapid economic growth prompted many youngsters to migrate to metropolitan areas which had abundant employment. Existing researches pointed out that many returned to their home prefectures, but this has not been satisfactory substantiated mainly due to a lack of migration history data. In a previous study (Esaki et al., 1999), we conducted a questionnaire survey and investigated this kind of return migration, namely U-turn migration, to Nagano Prefecture, which is within medium distance from the three largest metropolitan areas (Tokyo, Osaka and Nagoya). This study applied the same methodology to people born and raised in Miyazaki Prefecture, which is located in peripheral Japan, and aimed to obtain a general understanding of U-turn migration.Our questionnaire survey in the present study examined 1, 509 migration histories of male graduates from six high schools in Miyazaki Prefecture (1966-1968 and 1976-1978 graduates). A comparison of the survey results of the two Prefectures, Nagano and Miyazaki, revealed the following facts.First, the rate of U-turn migration from the three largest metropolitan areas to Nagano and Miyazaki was progressively higher for the younger generation. Among the younger generation, the return migration at graduation from university accounted for the larger proportion of all cases of U-turn migration, reflecting a rise in educational background.In case of the two Prefectures, the tendency of U-turn migration returning to the municipality where he had grown up becomes gradually stronger for the younger generation. Migrants' preference for their home municipalities, however, was slightly weaker in Miyazaki Prefecture. On the contrary, there were more 'J-turn' migrants, that is, U-turn migrants who returned not to their home municipalities but to the leading city in the Prefecture, namely Miyazaki City.Esaki et al. (1999) demonstrated that the birthplace of a man's wife was a very strong factor in his decision-making in favor of U-turn migration, although his academic background and whether or not he was the eldest son also affected it. This study confirmed the applicability of the results to the case of Miyazaki, in which those married with women born and raised in Miyazaki Prefecture were more likely to return than those married with women from other Prefectures.In terms of the timing of U-turn migration in accordance with an individual's working career, this study revealed that the majority of the migrants returned to Nagano and Miyazaki Prefectures within five to eight years after getting their first job. This indicates that U-turn migration mostly occurred shortly after they had started their lives in metropolitan areas. Therefore, we can conclude that U-turn migration is an option that young migrants who move away from rural regions may choose at the first turning point in their careers, with relatively little restriction regarding occupational and residential choice.

Traditional urban geography tends to place its research focus on the spatial differentiation of the functions and facilities in the metropolitan region. Little attention, however, has been paid to the drastic changes in everyday life of the urban residents. This review essay tries to overview the recent research trends in various academic fields which have a strong concern with human activities in an urban environment. In this way, some perspectives are suggested for human activity studies in urban geography.Human activities are allocated within both limited time resources and a constrained human activity space, and form the so-called‘human activity pattern’. Here we tentatively subdivided the researches on human activity into three categories: i. e.‘time budget and allocation study’which highlights the time dimension of human activity; ‘spatial behavior study’Which emphasizes the spatial choice; and‘transportation study’ which pays special attention to the human travel pattern. But these three types of studies are intricately entangled with each other and should be treated as a whole. Therefore, in this review essay, we try to understand each of these studies in its own research context and examine how other two types of studies could be evaluated in that context.Our viewpoint is briefly explained in Chapter One, and in the following chapter, we review the time budget and allocation studies in sociology, home economics and microeconomics which treat the time dimension of human activity. Basically, these studies treat the time allocation simply between production and consumption within 24 hours, and tend to be static analyses.In Chapter Three, we trace human activity pattern study in urban planning, human geography and transportation studies. These studies try to answer the question, ‘what activities do people engage in, and why?’The recent. frontier of this research interest is modelling of people's choice of activities within the constrained choice settings. Currently, research foci are on the dynamics of activity pattern change in the long-term and on repetitive patterns in the short-term.Chapter Four takes up time-geographic research in human geography for its tremendous influence on time-related studies. One of the most pronounced characteristics in time-geographic research is its endeavor to incorporate both time and space dimensions as indivisible entities in our understanding of the society. Introduction of an incorporated time-space entity is useful for representation of human activities. More importantly, however, it opens the way to mediation between individual behavior and social structure.Finally in Chapter Five, we discuss new perspectives for understanding of contemporary society. They would emerge from the time-geographical application of human activity studies. Three of them seem especially important. The first perspective is on the value of the identification procedure for ideal types of human activities. The second is on the use of examining human activities from the point of constraints. The third is on the need for a dynamic understanding of the interaction between individuals and society.However affluent it may seem, life in contemporary society is quite deprived when we see it from the point of everday time use. Economists can give support to the fact that economic growth makes time resources more scarce and our everyday life shifts from a time-intensive to a goods-intensive life-style. But we are not satisfied with this trend. We are still looking for clues to escape from the traps of economic growth. We hope this tiny study may help to research this horizon.