Sibling Configuration and Coresidence of Married Couples with an Older Mother in Japan

Abstract This study aims to clarify the effects of sibling configuration on both current and prospective coresidence of married male household heads with their older mother or mother-in-law. Multinomial logit analysis is applied to the data from the 1985 national household survey conducted by the Institute of Population Problems in Tokyo. The analysis is restricted to those heads whose mother and mother-in-law are both aged 60 or older and who do not live or plan to live with both mothers. The results of multinomial logit analysis of current living arrangements show a positive effect of the head's eldest-son status on coresidence with his mother and a positive effect of the wife's eldest-daughter status (in the absence of brothers) on coresidence with her mother, which supports the Heir Priority Hypothesis. The positive effects of the wife having older brothers or older sisters on coresidence with the head's mother also supports this hypothesis. On the other hand, the negative effects of the head having younger brothers or younger sisters and the wife being the youngest child, as well as the positive effect of the wife being the oldest child, on coresidence with the head's mother seem to support the House Crowding Hypothesis. The results of multinomial logit analysis of plans for future living arrangements, controlling for the current living arrangements, also show a similar (positive) effect of the head's eldest-son status on planned coresidence with his mother, supporting the Heir Priority Hypothesis. The reversed effect of the head having younger sisters on planned coresidence with his mother seems to be consistent with the Gender Role Crowding Hypothesis.     

An Edge-Splitting Algorithm in Planar Graphs

For a multigraph G = (V, E), let s V be a designated vertex which has an even degree, and let _G (V – s) denote min{c _G(X) | Ø X V – s}, where c _G(X) denotes the size of cut X. Splitting two adjacent edges (s, u) and (s, v) means deleting these edges and adding a new edge (u, v). For an integer k, splitting two edges e ₁ and e ₂ incident to s is called (k, s)-feasible if _G(V – s) k holds in the resulting graph G. In this paper, we prove that, for a planar graph G and an even k or k = 3 with k _G (V – s), there exists a complete (k, s)-feasible splitting at s such that the resulting graph G is still planar, and present an O(n ³ log n) time algorithm for finding such a splitting, where n = |V|. However, for every odd k 5, there is a planar graph G with a vertex s which has no complete (k, s)-feasible and planarity-preserving splitting. As an application of this result, we show that for an outerplanar graph G and an even integer k the problem of optimally augmenting G to a k-edge-connected planar graph can be solved in O(n ³ log n) time.     

A system for decision support without explicit objective functions

This paper presents a conversational decision support system: Resource Allocation in Business Operation under Uncertain Worth (RAINBOW). The focus is placed on the loosely structured decision situation where the multiple objective functions are given only implicitly and should be locally approximated by the decision maker as the decision making process proceeds. Basically, RAINBOW supports the process of convergence to a preferred alternative by giving the decision maker information which will help him form consistent evaluations of the utility function, the objective functions and the solution for the decision problem.     

Group predatory behavior by the assassin bugAgriosphodrus dohrniSignoret (Hemiptera: Reduviidae)

Summary Nymphs ofAgriosphodrus dohrni Signoret (Reduviidae) have a strong gregariousness and show group predatory behavior. This study was conducted to clarify adaptive significance of group predation of this species, including laboratory observations and 6-year field surveys. In the laboratory, observations on both solitary and group attacking against armyworms were made at varying prey size classes to compare the capture success rate by solitary predators with that by groups. The efficiency in capturing the prey was significantly higher in group attacking at any prey size class compared. Data obtained from the field surveys indicated the tnedency for searching nymphs to feed in group and to increase the number of predators feeding per prey item with increasing prey size. Average sizes of prey captured were also larger in group feeding throughout the nymphal stage. In particular, it was remarkable that, when prey were “creeping” types, the upper size limit of prey eaten was dramatically increased.     

Ecological studies of collembolan populations in a pine forest soil IV. Comparison of distribution patterns

Summary The distribution pattern of ten species of Collembola was studied during the four years period from July 1971 to May 1975 in a pine forest soil. The distribution patterns were analysed for two scales of distribution, i. e., the distribution over the plot of 10×10 m² and the micro-distribution within a block sample consisting of 36 contigious units each 2×2 cm² in area, by applying the -m regression method. The fundamental pattern which appeared was quite similar for the species examined and individuals were aggregated in response to the heterogeneity of habitat conditions. The causes of aggregations were discussed with regard to some environmental factors. The relative abundances of 10 species within the collembolan community was examined in relation to the habitat utilization and the relative abundance was not related to the degree of aggregation but rather to the area occupied by individuals. This suggests that the more numerically abundant species tend to occupy broader micro-habitat. Biological meaning of aggregation was discussed in connection with the population biology and community organization of collembola.     

Social security policy with public debt in an aging economy

This paper analyzes a social security policy with public debt in an overlapping generations growth model. In particular, the paper considers a situation in which population aging causes a heavy burden of social security payments where public debt is issued by the government to finance the payment. In the model presented below, an economy with an aging population may achieve two dynamically inefficient equilibria. Under certain conditions, the effects of pension reform and population aging on capital accumulation are entirely different between the two equilibria. Received: 23 July 2001/Accepted: 22 August 2002 I am deeply grateful to an anonymous referee and Professor A. Cigno, the Editor of this journal, for their valuable comments and suggestions. I am also grateful to Kazuyo Tanimoto and Kiheiji Nishida for their research assistance. Any remaining errors are my own. The research reported here was conducted as part of a larger study, the “Project on Intergenerational Equity” at the Institute of Economic Research, Hitotsubashi University. Financial support from Kani Hoken Bunka Zaidan is also gratefully acknowledged. Responsible editor: Alessandro Cigno.     

Housework, market work, and “doing gender” when marital satisfaction declines

When faced with a decline in marital satisfaction, are wives constrained from increasing their labor market work time in part because they “do gender?” One of the predictions of the human capital accumulation hypothesis, which assumes no constraints, is that housewives with little work experience will respond to a decline in marital satisfaction by increasing labor market work time (only). In contrast, the gender display hypothesis predicts that, in settings where the evaluations of marriage and wives’ work performance are closely intertwined, a decline in marital satisfaction among this group of housewives will increase both labor market work and housework—and the increase in housework serves as a constraint on the increase in labor market work. To evaluate these contrasting hypotheses, we analyze a panel survey of women in contemporary Japan. Results from multinomial logit regression models are more consistent with the gender display hypothesis than the human capital accumulation hypothesis. Housewives with relatively little work experience are 11 times more likely to increase the time spent on both labor market work and housework when the satisfaction of their marriage declines than when it does not. No evidence is found that, when marital satisfaction declines, these housewives are statistically significantly more likely to increase labor market work only.     

The Impact of Social Ties on Depressive Symptoms in U.S. and Japanese Elderly

This study examines the effects of social ties (with spouse, children, friends, neighbors, other relatives, and community groups) on depressive symptom levels in U.S. and Japanese adults aged 60 and over. Nationally representative survey data from the United States ( N = 1,419) and Japan ( N = 2,200) indicate that having a spouse, or increased contacts with friends, neighbors and relatives was associated with fewer depressive symptoms in both samples. The effects of spousal presence were significantly larger in the United States than in Japan. The presence of children was associated with fewer depressive symptoms in Japan only, and this effect was significantly stronger among those currently unmarried as opposed to those who are currently married. We discuss these similarities and differences between countries.     

Density-dependent predation of the antLasius niger (Hymenoptera: Formicidae) on two attended aphidsLachnus tropicalis andMyzocallis kuricola (Homoptera: Aphididae)

The antLasius niger was observed collecting honeydew and preying on the two aphid speciesLachnus tropicalis andMyzocallis kuricola on the chestnut treesCastanea crenata. Observation determined how the antL. niger controlled their predation on the aphids in response to the density and honeydew-productivity of the aphids.Lachnus tropicalis was a better honeydew source thanM. kuricola forL. niger in terms of the amount of honeydew collected per unit time by the ants. The number of foraging workers on a tree increased with the number ofL. tropicalis on the tree, but not with the number ofM. kuricola. The density ofL. tropicalis perL. niger worker on a tree had a positive effect on the predation activity ofL. niger on both aphids, whereas the density ofM. kuricola per ant did not have any significant effect. The predation pressure by the ant which increased withL. tropicalis density, however, directed toM. kuricola rather than toL. tropicalis. These facts suggest (1) thatL. niger control their predation activities on aphids with regards to the densities of the attended aphids per worker, and (2) that the ants prey on the aphid species producing less honeydew. The effects of the ant predation on aphids and the importance of these predation effect in antaphids interactions were discussed.     

用EMME／2建立交通模型：广岛城区的交通研究

过去的３０年，日本广域区已经帮了３个交通规划的研究，在这些研究中所使用的软件已得到有关部门的进一步开发。一般来说，为广岛项目建立的模型还没有在其他地区和，也缺少这些软件使用的有关信息。本研究的目标是为广岛城区使用ＥＭＭＥ／２建立交通模，以评估和探索ＥＭＭＥ／２的可用性，这包括用１９８７年广岛城区交通数据建立模型，以调整的ＥＭＭＥ／２模型得到结果同１９８７年观测的交通数据进行核对，ＥＭＭＥ／２的可适