Hadronic decay of the gravitino in the early universe and its implications to inflation

We discuss the effects of the gravitino on the big-bang nucleosynthesis (BBN), paying particular attention to the hadronic decay mode of the gravitino. We will see that the hadronic decay of the gravitino significantly affect the BBN and, for the case where the hadronic branching ratio is sizable, very stringent upper bound on the reheating temperature after inflation is obtained.Comment: 6 pages, 2 Postscript figures, Talk given at PASCOS'04 (Boston, MA, August 16 -- 22 (2004

Revisiting Big-Bang Nucleosynthesis Constraints on Dark-Matter Annihilation

We study the effects of dark-matter annihilation during the epoch of big-bang nucleosynthesis on the primordial abundances of light elements. We improve the calculation of the light-element abundances by taking into account the effects of anti-nucleons emitted by the annihilation of dark matter and the interconversion reactions of neutron and proton at inelastic scatterings of energetic nucleons. Comparing the theoretical prediction of the primordial light-element abundances with the latest observational constraints, we derive upper bounds on the dark-matter pair-annihilation cross section. Implication to some of particle-physics models are also discussed.Comment: 10 pages, 2 figure

Corporate Finance and Human Resource Management

Corporate governance can be defined to be an institution that constrains relations between corporate managers and various stakeholders, including shareholders, creditors, workers, suppliers, and customers. Under this broad definition, corporate governance is a system of various sub-systems that are complementary to one another. This paper focuses on two sub-systems of the Japanese corporate governance: one on corporate finance and another on human resource management. After briefly documenting the characteristics of the Japanese corporate governance in these two sub-systems, the paper discusses how each sub-system has been going through substantial changes in recent years. Examining the data for 58 listed companies, we find preliminary evidence on the complementarity between the two sub-systems. The firms that have non-traditional ownership structure (especially high foreign ownership) seem to have more non-traditional human resource management practices.

Cosmic Rays from Dark Matter Annihilation and Big-Bang Nucleosynthesis

Recent measurements of cosmic-ray electron and positron fluxes by PAMELA and ATIC experiments may indicate the existence of annihilating dark matter with large annihilation cross section. We show that the dark matter annihilation in the big-bang nucleosynthesis epoch affects the light element abundances, and it gives stringent constraints on such annihilating dark matter scenarios for the case of hadronic annihilation. Constraints on leptonically annihilating dark matter models are less severer.Comment: 21 pages, 5 figures; added references; corrected the electromagnetic-emission part and got milder constraint from the photodissociation processes by a factor of 50 (v3

Internal migration and utilization of reproductive and maternity care among women in Pakistan: evidence from a recent National Survey

Background: During the last decades, migratory behavior has had a key role in population growth and redistribution in Pakistan. Migration has far-reaching socioeconomic implications for individuals and society at large that could influence the health integrity of Pakistani women. This study aimed to describe the migration patterns and drivers as well as their association with adequate access to reproductive and maternal care among married Pakistani women aged 15–49. Methods: The data from the 2017–18 Pakistan Demographic Health Survey (PDHS) was used to extract the information on the explanatory (sociodemographic and migration backgrounds) and outcome variables (unmet needs for family planning, adequate antenatal care, and delivery at health facilities). Bivariate and multivariate logistic regression analyses were employed to examine the relationship between these explanatory and outcome variables before and after adjustment for sociodemographic inequalities. Results: In unadjusted models, the odds of having adequate ANC and delivery at health facilities were approximately 2 to 4 times higher in those living (urban non-migrant), moving to (urban to urban, rural to urban), or leaving the urban areas (rural to urban) as compared to rural non-migrants; likewise, the odds of the unmet needs for family planning was about 20–50% lower in the same migration streams compared to rural non-migrant. However, after adjustment for sociodemographic inequalities, most of these associations attenuated and only the association of urban to urban migration with unmet needs for family planning and the association of urban non-migrant with delivery at health facilities remained significant. Conclusion: Although the findings suggest that Internal migration flows, particularly those to urban areas (urban to urban and rural to urban), could be associated with better access to reproductive and maternity care among married Pakistani women aged 15–49 years; adjustment for sociodemographic inequalities, particularly education and wealth, nullified this association to a great extent. This has important implications for current policies and interventions in Pakistan and calls for policy reform and women’s rights advocacy to enhance the literacy level of young Pakistani girls through well-tailored interventions, maintaining them at school.publishedVersio