Survivorship and fertility schedules of two Sumatran tortoise beetles,Aspidomorpha miliaris andA. sanctaecrucis (Coleoptera: Chrysomelidae) under laboratory conditions

Summary Two species of tortoise beetles,Aspidomorpha miliaris (AM) andA. sanctaecrucis (AS) feeding on a shrub-like morning glory,Ipomoea carnea, were reared under laboratory conditions to study their survivorship and fertility schedules. AM and AS required 34–39 days and 30–37, respectively, for the development of the immature stages. The mean longevity of the males was 88.4 days in AM and 63.8 in AS, and that of females was 87.9 days in AM and 83.3 in AS. The mean length of the pre-reproductive period (27.2 days in AM and 33.8 in AS) was much longer than that of the post-reproductive period (10.9 days in AM and 14.3 in AS). Females laid eggs at a nearly constant rate throughout their reproductive period. The reproductive valueV _x /V ₀ of the two species remained high for most of their adult life, as a result of prolonged survivorship and fertility periods. The total number of eggs produced per female was 442.9 (AM) and 80.1 (AS). The intrinsic rate of natural increaser was 0.070 (AM) and 0.044 (AS) per capita per day. The prolonged reproductive schedules, coupled with strong dispersal power, of these species no doubt have an adaptive value for living in highly disturbed tropical environments, where rainfall is ample but unpredictable and food resources are available throughout the year in a wide area, but distributed in widely flung patches. Contributions to the knowledge of population dynamics of tortoise beetles in Sumatra 3. Contribution No. 33 of Sumatra Nature Study (Entomology). Partly supported by Grants from Japan Society for Promotion of Science for JSPS-DGHE Scientific Cooperation (1980, 1982) and Grants-in-Aid for Overseas Scientific Survey from Ministry of Education, Science and Culture of Japan (Nos. 56041027 and 58041030).     

Prey capture tactics of spiders: An analysis based on a simulation model for spider's growth

Summary The prey capture tactics of spiders was analyzed, considering the energy gained by the capture of prey and that required for it. For the purpose of it, a growth model of spiders was constructed, expressing the flow rate of prey biomass to the spider's body by differential equations. Solving these equations under the differing values of three parameters, growth curves of spiders was obtained. These three parameters are the amount of prey biomass supplied daily to spiders,x ₀, the rate of prey capture of spiders, α, and a coefficient of the respiration rate required for the capture of prey,k. When the value ofk increased, spiders could grow only at high value ofx ₀. These results suggest that habitats with small prey biomass are preferred by spiders adopting a sit-and-wait tactics for prey capture, which requires small values ofk. Wolf spiders are one of these spiders showing that tactics. On the other hand, web-builders which require large amount of energy for spinning webs (namely, take large value ofk), are able to grow only in the habitats with large prey biomass. Each species of spiders are considered to locate in a certain point between both extremes of these tactics for the capture of prey.     

The feeding from edge towards inner part in soybean plot in rufous turtle dove,Streptopellia orientalis (Latham) and the estimation of passing rate of the flock

Summary Rufous turtle dove,Streptopelia orientalis, coming to the soybean field entered it from the outer part to eat soybean cotyledons. As a result, the injured plants extended from the outer to inner parts in the field. A model expressing these behaviours was constructed here, by assuming that the amount of food birds can eat in one block determines whether they stay there or move into neighbour block. As the food decrease due to exploitation of them by birds, birds enter into farther parts with the passage of time. The rate of feeding in all visiting birds (an ₀ wherea is the rate of feeding per individual andn ₀ the number of birds visiting) and the rate of staying at a block,b, was estimated from the field experimental results, using the above model. The value ofan ₀ fluctuated greatly, depending upon the season in which soybean seeds sowed. The value ofb also fluctuated inversely with that ofan ₀, suggesting the the staying rate decreases with an increase in the number of doves coming, probably because of interference among individuals.     

日本的东洋史研究

日本的东洋史研究,中国史占绝对多数。回顾东洋史研究,是按王朝和地域确定研究范围;文学的两大中心东京帝国大学和京都帝国大学有着不同的治学风格;对中国各时代的研究都有代表性的学者涌现。最近证实个别问题的研究较多,题目多种;人们关注新发掘的资料;中日历史学界考察、交流情况越来越多。日本除了在大学增设东洋史专业教育外,还拥有专门的研究机构,刊载东洋史的学术刊物陆续涌现。     

Wages of regular and irregular workers, the price of education, and income inequality

In this paper, we develop a model characterized by skill-biased technological change and increasing costs of education to investigate income inequality. Irregular workers cannot escape poverty by commencing investment in education because wage inequality between regular and irregular workers widens and the price of education increases with the average level of education. Moreover, if the productivity of elementary education is low relative to that of higher education, middle-income individuals are eventually unable to pursue higher education because the threshold for education expenditure rises with the price of education. Thus, income inequality may widen, even among regular workers.     

Experimental studies on the distribution of the aphid counts

Summary The present paper dealt with the sequential changes of the distribution pattern of apterous females aphid populations, that were artificially settled at the beginning on the experimental barley ‘field’. The aphids were settled at random or even with a fixed denisty per plant. For five or six days after the settling, the number of individuals followed the negative binomial distributions in all cases while the parametersk andp were varying. The estimated values ofk were rather small for the first one week after the settling, which may suggest that the number of moving aphids between plants was relatively small and the degree of concentration expressing the intrinsic increase was high. After that, as the number of individuals increased, the number of moving aphids between plants would be considered to be increased. It was found that with the lapse of time the degree of concentration decreased ork became larger. The distribution of aphids per blade in a plant was also described briefly.     

The ingestion in wolf spiders II. The expression of degree of hunger and amount of ingestion in relation to spider's hunger

Summary To express the degree of hunger during both of feeding and unfeeding periods of spiders, equations for the amount of ingestion and food disappearance from the gut were presented using three components: capacity of gut, rate of ingestion and rate of food disappearance. The degree of hunger was expressed by the rate of unfilled capacity of gut to the capacity of gut based on these equations. The rates of ingestion and food disappearance were estimated from the results of experiment with a wolf spider,Pardosa laura. The equations obtained well applied to the experimental result. By changing values of these rates, it was revealed that the ratio of rates of ingestion to food disappearance determine the amount of ingestion.     

Strategic management in major Japanese hightech companies

Since the early 1980s, there has been remarkable progress in advanced technology in Japan and in leading Western countries. What is the present situation in technological development in major Japanese industries and what are the implications for strategic management? The author describes how Japanese industries have harnessed new technologies and suggests a number of concepts which underly these trends. Given the imperatives of advanced technology, he emphasizes the importance of positioning the technology development strategy in the context of strategic management paying particular attention to developing an open organizational culture through a flexible corporate planning system.     

日本横滨大同学校之创立

日本横滨大同学校是康有为、梁启超等维新派和孙中山、陈少白等革命派共同创办的华侨子弟教育机构。以前的研究由于资料不足和革命派与维新派的记载互有出入，所以关于大同学校的创办日期众说纷纭，正确的说法应该是分别从“创立”、“开校”两个不同层面来判断。日本大同学校的创立不仅反映了革命派与维新派的不同教育价值观，也折射出清末政治的潮起潮落。