- 著者
- Hiroshi HAMADA
- 出版者
- The Japan Academy
- 雑誌
- Proceedings of the Japan Academy, Series B (ISSN:03862208)
- 巻号頁・発行日
- vol.96, no.7, pp.273-296, 2020-07-31 (Released:2020-08-12)
- 参考文献数
- 158
- 被引用文献数
- 16 35
Although the human body appears superficially symmetrical with regard to the left–right (L-R) axis, most visceral organs are asymmetric in terms of their size, shape, or position. Such morphological asymmetries of visceral organs, which are essential for their proper function, are under the control of a genetic pathway that operates in the developing embryo. In many vertebrates including mammals, the breaking of L-R symmetry occurs at a structure known as the L-R organizer (LRO) located at the midline of the developing embryo. This symmetry breaking is followed by transfer of an active form of the signaling molecule Nodal from the LRO to the lateral plate mesoderm (LPM) on the left side, which results in asymmetric expression of Nodal (a left-side determinant) in the left LPM. Finally, L-R asymmetric morphogenesis of visceral organs is induced by Nodal-Pitx2 signaling. This review will describe our current understanding of the mechanisms that underlie the generation of L-R asymmetry in vertebrates, with a focus on mice.
- 著者
- Hiroshi HAMADA
- 出版者
- Japanese Association For Mathematical Sociology
- 雑誌
- 理論と方法 (ISSN:09131442)
- 巻号頁・発行日
- vol.31, no.2, pp.242-260, 2016 (Released:2017-01-16)
- 参考文献数
- 58
The purpose of this study is to formalize a generative model for income and capital inequality by focusing on the accumulation process of human and network capital. Using this model, we attempt to provide theoretical explanations to three empirical questions. First, why is the relationship between economic growth and income inequality expressed as an inverted U-curve? Second, why does societal relative deprivation increase when economic growth rises (the so-called China puzzle)? Third, why is income inequality stable despite the reduction of human capital inequality? The model assumes that people in a society experience repeatedly random chances of gaining capital interest with a success probability p. People gain additional capital as an interest when they succeed and incur a cost when they fail randomly. We show that the capital distribution approaches a lognormal distribution, and as an output of Cobb-Douglas production function, income distribution is also subject to a lognormal distribution. Analyzing the Gini coefficient and the average income as a function of parameters of the model, we derive the following implications. 1) The inverted U-curve is realized by the expansion of success chance. 2) The China puzzle occurs because the increase of average income and Gini coefficient are simultaneously followed by the expansion of success probability p under the range p∈(0,0.5). 3) The income inequality is stable, though human capital inequality decreases because of human and network capital elasticity and network capital diminishes the impact of human capital equalization on income inequality.