Family formation trends and patterns of women's work trajectories in South Korea : determinants and cohort differences

We use sequence analysis on data from the Korean Labor & Income Panel Study (1998–2019) to investigate trajectories of women’s labour market participation in the eight years after first childbirth. We pay special attention to the type of employment through which mothers participate in the labour market, distinguishing between regular full-time employment, non-regular employment, self-employment, and non-employment. After creating employment sequences, we use cluster analysis to reveal patterns of employment trajectories and average marginal effects derived from multinomial logistic regression to identify women’s characteristics on the distinct trajectories. We find that women of younger cohorts are less likely to solely focus on family and childcare in the years after childbirth. However, their chances of steady work in regular jobs did not increase. Instead, they are more likely to be on unsteady pathways, combining childcare with regular or non-regular jobs. Our results suggest that increases in females’ employment might be partly attributed to mothers’ higher probability to obtain precarious non-regular work jobs. Our results suggest that increases in females’ employment might be partly attributed to mothers’ higher probability to obtain precarious non-regular work

Management of Residential Environment for Maturation of Neighborhoods

学位の種別: 課程博士審査委員会委員 : （主査）東京大学教授 出口 敦, 東京大学教授 味埜 俊, 東京大学准教授 清家 剛, 東京大学准教授 清水 亮, 東京大学特任教授 窪田 亜矢University of Tokyo(東京大学

Does size matter for horny beetles? A geometric morphometric analysis of interspecific and intersexual size and shape variation in Colophon haughtoni Barnard, 1929, and C. kawaii Mizukami, 1997 (Coleoptera: Lucanidae)

Colophon is an understudied, rare and endangered stag beetle genus with all species endemic to isolated mountain peaks in South Africa’s Western Cape. Geometric morphometrics was used to analyse intersexual and interspecific variation of size and shape in the mandibles, heads, pronota and elytra of two sympatric species: Colophon haughtoni and Colophon kawaii. All measured structures showed significant sexual dimorphism, which may result from male-male competition for females. Female mandibles were too small and featureless for analysis, but male Colophon beetles possess large, ornate mandibles for fighting. Males had significantly larger heads and pronota that demonstrated shape changes which may relate to resource diversion to the mandibles and their supporting structures. Females are indistinguishable across species, but males were accurately identified using mandibles, heads and pronota. Male C. kawaii were significantly larger than C. haughtoni for all structures. These results support the species status of C. kawaii, which is currently in doubt due to its hybridisation with C. haughtoni. We also demonstrate the value of geometric morphometrics as a tool which may aid Colophon conservation by providing biological and phylogenetic insights and enabling species identification

Changes in Precarious Employment Among South Korean Women

How does continuity of employment affect precariousness of South Korean women over their life cycle? A multilevel discrete-time logit model shows that marriage and the presence of young children do not worsen precariousness, but poor quality of employment and low occupational status confine women to precarious statuses. Escaping from precarious employment comes from higher educational attainment and longer periods of paid employment

Precarious employment among South Korean women: Insights from a comparison to France

Family responsibilities for women are often associated with precarious employment. This relation varies depending on whether women can reconcile family life and work or not. Based on the Korean Labor and Income Panel Study from 1998 to 2008 and on the French part of the European Community Household Panel between 1998 and 2001, a multiple correspondence analysis shows that precariousness in employment is correlated with family life and levels of education. The better conditions of work-family balance in France enable young mothers to combine family life with stable employment of good quality, which is not the case for South Korean women. The comparison of the two countries highlights the necessary reforms in favor of women’s better being

What has contributed to the large sex differentials in lifespan variation and life expectancy in South Korea?

To date, research on sex differentials in lifespan variation and life expectancy has mainly been conducted in Western countries and there is a dearth of data from South Korea. This study aimed to further the understanding of mortality transition and life expectancy in South Korea, and the associated trajectories of age-at-death variation, through an analysis of life disparity by gender. Using complete life tables for South Korea for 1970–2015, sex differentials (female–male differences) in life disparity and life expectancy at birth were estimated, and sex differentials in life expectancy were decomposed by age and cause of death. The results showed that sex differentials in life expectancy at birth have not reduced significantly in the last 45 years (1970: 7.1 years; 2015: 6.2 years). Life disparity has reduced more rapidly for females than males, and the difference increased from −0.1 year in 1981 to −1.6 years in 2015. Sex differentials in life expectancy and life disparity in South Korea were higher during 1970–2015 than in several Western countries with high life expectancy. The elderly age group (60 and above) contributed 50% of the total sex difference in life expectancy at birth in 1970, and this increased to 70% in 2015. The contribution of the age group 15–59 years reduced significantly over the period. Decomposition of life expectancy at birth by cause revealed that diseases of the circulatory system (2.2 years), followed by external causes (1.3 years), were the most important causes of the sex differences in life expectancy at birth in 1983, and in 2015 neoplasms (2.2 years) and external causes (1.1 years) explained half of the total sex differences. There has been a significant shift in the age-specific pattern of the contribution towards each cause of death. Overall, sex differentials in life disparity and life expectancy at birth have remained significant in South Korea in the last 45 years

Who does not intend to retire? Mothers' opportunity costs and compensation at later ages in Europe

Research investigating the association between women’s work–family trajectories and their retirement intentions is limited. Studies considering how different institutional conditions affect this association are even more limited. To fill this gap, we use the first three waves of the Survey of Health, Ageing and Retirement in Europe, 2004–2009, and apply two-level random effects models with country-level fixed effects to a sample of mothers aged 50–64 years. Our dependent variable is the intention to retire as early as possible. We found that the following two different mechanisms are associated with mothers’ early retirement intentions: (a) strategies to compensate for opportunity costs and (b) work attachment. When all other factors are equal, mothers with a work career characterised by interruptions and part-time work intend to work longer than other mothers, indicating the need to compensate for lower lifelong earnings at older ages. Some compensatory strategies are also observed among mothers who are classified as ‘never married’, ‘divorced’ or ‘widowed’, who wish to continue their careers. In other cases, evidence supporting work attachment mechanisms is found; for instance, working when the youngest child is younger than six years predicts the intention to delay retirement. These results change according to the welfare regime, underlining the importance of family policies and pension benefits to counterbalance the effect of opportunity costs on mothers’ earnings

Engineering of formate-hydrogen lyase gene cluster for improved hydrogen production in Escherichia coli

The formate-hydrogen lyase (FHL) complex of Escherichia coli catalyzes the conversion of formate to hydrogen (H-2) and carbon dioxide (CO2) under anaerobic conditions in the absence of exogenous electron acceptors. The FHL complex consists of formate dehydrogenase (FdhH) and hydrogenase 3 (Hyd3) that are involved in a series of reactions, including formate oxidation (by FdhH), electron transport (by putative five small subunits of Hyd3) and proton reduction (by HycE, large subunit of Hyd3). In this study, the FHL gene cluster and iscR, a negative regulator of iron-sulfur cluster, of E. coli SH5 (BW25113 Delta hycA Delta hyaAB Delta hybBC Delta ldhA Delta frdAB) were altered to increase the FHL-dependent H-2 production activity. When FhlA, a transcriptional regulator of FHL, was overexpressed, the FHL-dependent H-2 production activity was improved significantly to 2.03 mu mol H-2 mg(-1) cdw min(-1) from 1.41 mu mol H-2 mg(-1) cdw min(-1). When an iscR deletion and/or fdhF overexpression was added, the whole-cell FHL activity was improved further to 2.80 mu mol H-2 mg(-1) cdw min(-1) (with Delta iscR) and 2.45 mu mol H-2 mg(-1) cdw min(-1) (with Delta iscR plus fdhF overexpression), respectively. The increase in whole-cell FHL activity was accompanied by an increase in the activity of its member enzymes, such as HycE and/or FdhH. In addition, the highly active recombinant strains exhibited stable performance during prolonged H-2 production with the repeated addition of formate. Overall, the FHL-dependent H-2 production activity of E. coli can be improved more than three-fold by modifying the expression of the relevant genes