What are the factors of the gap between desired and actual fertility? - A comparative study of four developed countries

This study is an analysis of the gap between the desired and actual number of children for four developed countries. Although the direct costs of raising children is an indispensable element in decision-making regarding having children, it has hardly been treated in relevant studies. We estimate the achievement rate of having the desired number of children by many possible elements, including the direct costs of raising children. The results show significant negative impacts of these direct costs as well as delayed marriage as the main causes for low achievement of desired fertility (Japanese men and women, Korean men). Also, the sexual division of labor affects the wife’s achievement rate in Japan, depending on the husband’s employment situation. No noteworthy negative impact was found in the case of high achievement of desired fertility (French men and women, American men).Our results suggest that reducing the direct costs of raising children and stabilizing the employment situation should be given priority rather than other measures with regard to achieving desired fertility.Fertility, Costs of children, Work-life balance, Job security

Constraints on Generalized Dark Energy from Recent Observations

Effects of a generalized dark energy fluid is investigated on cosmic density fluctuations such as cosmic microwave background. As a general dark energy fluid, we take into consideration the possibility of the anisotropic stress for dark energy, which has not been discussed much in the literature. We comprehensively study its effects on the evolution of density fluctuations along with that of non-adiabatic pressure fluctuation of dark energy, then give constraints on such a generalized dark energy from current observations. We show that, though we cannot find any stringent limits on the anisotropic stress or the non-adiabatic pressure fluctuation themselves, the constrains on the equation of state of dark energy can be affected in some cases by the nature of dark energy fluctuation characterized by these properties. This may have important implications to the strategy to study the nature of dark energy.Comment: 17 pages, 12 figure

Dark matter kinetic decoupling with a light particle

We argue that the acoustic damping of the matter power spectrum is not a generic feature of the kinetic decoupling of dark matter, but even the enhancement can be realized depending on the nature of the kinetic decoupling when compared to that in the standard cold dark matter model. We consider a model that exhibits a ${\it sudden}$ kinetic decoupling and investigate cosmological perturbations in the ${\it standard}$ cosmological background numerically in the model. We also give an analytic discussion in a simplified setup. Our results indicate that the nature of the kinetic decoupling could have a great impact on small scale density perturbations.Comment: 19 pages, 7 figure

Structural Data Recognition with Graph Model Boosting

This paper presents a novel method for structural data recognition using a large number of graph models. In general, prevalent methods for structural data recognition have two shortcomings: 1) Only a single model is used to capture structural variation. 2) Naive recognition methods are used, such as the nearest neighbor method. In this paper, we propose strengthening the recognition performance of these models as well as their ability to capture structural variation. The proposed method constructs a large number of graph models and trains decision trees using the models. This paper makes two main contributions. The first is a novel graph model that can quickly perform calculations, which allows us to construct several models in a feasible amount of time. The second contribution is a novel approach to structural data recognition: graph model boosting. Comprehensive structural variations can be captured with a large number of graph models constructed in a boosting framework, and a sophisticated classifier can be formed by aggregating the decision trees. Consequently, we can carry out structural data recognition with powerful recognition capability in the face of comprehensive structural variation. The experiments shows that the proposed method achieves impressive results and outperforms existing methods on datasets of IAM graph database repository.Comment: 8 page

Effects of Cosmological Moduli Fields on Cosmic Microwave Background

We discuss effects of cosmological moduli fields on the cosmic microwave background (CMB). If a modulus field \phi once dominates the universe, the CMB we observe today is from the decay of \phi and its anisotropy is affected by the primordial fluctuation in the amplitude of the modulus field. Consequently, constraints on the inflaton potential from the CMB anisotropy can be relaxed. In particular, the scale of the inflation may be significantly lowered. In addition, with the cosmological moduli fields, correlated mixture of adiabatic and isocurvature fluctuations may be generated, which results in enhanced CMB angular power spectrum at higher multipoles relative to that of lower ones. Such an enhancement can be an evidence of the cosmological moduli fields, and may be observed in future satellite experiments.Comment: 11pages, 4 figures, numerical error correcte