The backward-bending commute times of married women with household responsibility

The purpose of this paper is to examine theoretically and empirically whether the commute times of married women follow a backward-bending pattern with respect to wage rates. The existing literature has shown that married women tend to choose short commutes because of their relatively low wages combined with comparatively heavy household responsibilities. However, a workleisure model, which includes the simultaneous decision wives take regarding commute times and wage rates, suggests that married women employed in highly paid positions also undertake short commutes, while married women with wage rates in the middle range choose long commutes. These results suggest that the commute times of married women display a backward-bending pattern. Applying an instrumental variable strategy that accounts for the endogeneity of wage rates, the empirical results for employed married women in Japan appear to support this nding. Moreover, one of our results suggests that highly paid married women can still secure greater leisure time with short commutes, despite retaining a heavy load of domestic responsibilities.Working Paper, No.234, 2008.9.1版http://hdl.handle.net/10110/254

The Kuiper Belt and Other Debris Disks

We discuss the current knowledge of the Solar system, focusing on bodies in the outer regions, on the information they provide concerning Solar system formation, and on the possible relationships that may exist between our system and the debris disks of other stars. Beyond the domains of the Terrestrial and giant planets, the comets in the Kuiper belt and the Oort cloud preserve some of our most pristine materials. The Kuiper belt, in particular, is a collisional dust source and a scientific bridge to the dusty "debris disks" observed around many nearby main-sequence stars. Study of the Solar system provides a level of detail that we cannot discern in the distant disks while observations of the disks may help to set the Solar system in proper context.Comment: 50 pages, 25 Figures. To appear in conference proceedings book "Astrophysics in the Next Decade

Genomic prediction model optimization for growth traits of olive flounder (Paralichthys olivaceus)

Genomic prediction (GP) has emerged an effective tool for addressing the many shortcomings of traditional selective breeding, thereby enhancing the selection process. In this study, we optimized GP methods using 5-fold cross-validation to estimate genome-estimated breeding values for the weight traits of olive flounder (Paralichthys olivaceus). To accomplish our goal, we determined the parentage of the target broodstock and the ability of 11 prediction models to predict the weight traits of 1.8-year-old olive flounders, which were genotyped using a 70 K single nucleotide polymorphism (SNP) array. Moreover, our optimization efforts toward the predictive ability of genomic best linear unbiased prediction (GBLUP), Bayesian B (BB), and random forest (RF) methods encompassed changes in various aspects such as fixed effects, SNP quantity, population size, and phenotypic data collected at different fish ages. Additionally, we assessed the predictive ability for the total length and body depth of fish using GBLUP, BB, and RF. Among the 11 prediction methods used in this study, the BB (0.675), Elastic Net (0.679), and RF (0.698) methods exhibited the highest predictive abilities, whereas the GBLUP (0.637) method demonstrated the lowest. Incorporating information regarding fish sex as a fixed effect substantially improved the predictive ability of GBLUP and BB. For mean models, utilizing 3000–5000 random SNP markers resulted in a higher predictive ability, similar to that obtained using 50,000 SNPs. Increasing the population size reduced the standard deviation of the predictive ability. Notably, phenotypic records from 1.8-year-old fish exhibited a significantly higher predictive ability than those from the other age groups. Furthermore, GBLUP, BB, and RF provided higher predictive abilities for length (0.655–0.852) and body depth (0.665–0.861). These findings may significantly shape future olive flounder genomic selection programs and offer valuable insights into GP in aquaculture

Genome-wide association study (GWAS) of growth traits in olive flounder (Paralichthys olivaceus)

Traits linked to growth performance in farmed fish are major drivers of profitability in aquaculture systems. Given the importance of growth-related traits, there have been efforts to unravel the genomic architecture of growth traits and to identify key genes or genomic regions useful as selection markers in various species. Such markers would increase the accuracy of selection and improve rates of genetic progress for growth improvement in breeding programs. Olive flounder (Paralichthys olivaceus) has a considerable market value in Asia and is mainly cultured in South Korea. To facilitate a breeding program for this species, a genome-wide association study (GWAS) was conducted to identify single nucleotide polymorphisms (SNP) associated with growth traits. In total, 1800 fish were measured for body weight (BW), total length (TL), and maximum body depth (BD). Fish were genotyped using the Affymetrix® Axiom® myDesign™ Genotyping Arrays; 1009 fish and 58,756 SNPs remained after the final quality control check. According to the phenotypes, female fish recorded higher BW, TL, and BD than male counterparts of the same age, revealing a sex-dependent growth pattern. There was a strong positive phenotypic correlation (0.945–0.965) and a moderate genotypic correlation (0.286–0.332) between the three growth performance traits of the 1009 fish. Eight SNPs were identified above the significant (p < 8.5 × 10−7) and suggestive (p < 1 × 10−5) thresholds for all traits, and they were mapped primarily onto chromosomes 23 and 24. According to the GWAS analysis, genotypes at loci AX-419206420 and AX-419307742 significantly affected the growth performance of the population. Gene ontology (GO) analysis was performed on 30 candidate genes with notable growth performance effects (p < 1 × 10−4) and GO terms related to neuron development, molecule binding and cytoskeleton organization were highly enriched. Our findings may contribute to understanding of the molecular basis of growth regulation and promote the use of SNP-based genomic selection in flounder culture

Identification of candidate variants and genes associated with temperature tolerance in olive flounders by Genome-Wide Association Study (GWAS)

The Republic of Korea is one of the largest producers of farm-raised olive flounder (Paralichthys olivaceus), accounting for nearly half of the global production. However, global warming has affected the aquaculture industry worldwide as it impacts survival, growth, and immunity and accelerates increases in pathogen load. In this study, we identified thermal stress-related genes in olive flounder using a genome-wide association study (GWAS) to provide a basis for marker-assisted selection and the development of temperature-resistant olive flounder in response to global warming. In total, 768 healthy olive flounder (weight of 159 ± 29.9 g and length of 25.42 ± 1.63 cm) were subjected to thermal stress (19.4–32.5 °C), and dead fish (537) were collected every 30 min. The fin tissues were isolated from all dead and surviving fish (231) and used for gDNA extraction. A high-quality 70 K SNP chip was used for genotyping, and 58,920 SNPs were obtained from 726 individuals after quality filtering. The GWAS identified 216 statistically significant SNPs at the Bonferroni cutoff (8.5 × 10−7). All significant SNPs were located on chromosome (chr) 18 (39 SNPs), chr 19 (176 SNPs), and contig 28 (AGQT02031776.1). After the SNP annotation, 13, 67, and 135 SNPs were identified in exons, introns, and intergenic regions, respectively. Gene and functional annotations revealed that almost all significant SNPs were directly or indirectly associated with the thermal stress response. Annotated genes were further categorized into the following functional groups: metabolic, neural and neuroendocrine, molecular and cellular, and physiological and behavioral responses. The significant SNP-harboring genes identified in this study could be used for marker-assisted genomic selection in future breeding programs

Genome-wide association study of VHSV-resistance trait in Paralichthys olivaceus

In flounder aquaculture, selective breeding plays a vital role in the development of disease-resistant traits and animals with high growth rates. Moreover, superior animals are required to achieve high profits. Unlike growth-related traits, disease-resistant experiments need to be conducted in a controlled environment, as the improper measurement of traits often leads to low genetic correlation and incorrect estimation of breeding values. In this study, viral hemorrhagic septicemia virus (VHSV) resistance was studied using a genome-wide association study (GWAS), and the genetic parameters were estimated. Genotyping was performed using a high-quality 70 K single nucleotide polymorphism (SNP) Affymetrix® Axiom® myDesign™ Genotyping Array of olive flounder. A heritability of ∼0.18 for resistance to VHSV was estimated using genomic information of the fish. According to the GWAS, significant SNPs were detected in chromosomes 21, 24, and contig AGQT02032065.1. Three SNPs showed significance at the genome-wide level (p < 1 × 10−6), while others showed significance above the suggestive cutoff (p < 1 × 10−4). The 3% phenotypic variation was explained by the highest significant SNP, named AX-419319631. Of the important genes for disease resistance, SNPs were associated with plcg1, epha4, clstn2, pik3cb, hes6, meis3, prx6, cep164, siae, and kirrel3b. Most of the genes associated with these SNPs have been previously reported with respect to viral entry, propagation, and immune mechanisms. Therefore, our study provides helpful information regarding VHSV resistance in olive flounder, which can be used for breeding applications