Sectorial sift, inverted U-shaped fertility dynamics, and growth

This paper constructs a small open two-sector overlapping-generations model with the subsistence level of consumption of agricultural goods and explains the following key stylized facts in the process of economic development: increases followed by declines in fertility rate, increases in human capital investment for children, and a sectorial shift in labor from agriculture to manufacture.Demographic transition Sectorial sift Economic development

Organizational Modes within Firms and Productivity Growth

This paper develops a simple growth model with moral hazard contracting to examine the interactions between the organizational mode of firms and economic productivity growth. The organizational mode of firms differs in terms of the degree to which decisions of R&D investment are delegated to a manager. We show that the market size restricts the extent of delegation with respect to R&D, which in turn determines the productivity growth rate of the economy. We then show that there exist multiple equilibria: gpartial decentralization equilibriumh with a low growth rate and gfull decentralization equilibriumh with a high growth rate. Finally, we study the effects of social capital and competition on equilibrium organizational modes and show that, under some parametric conditions, these factors induce more decentralized organization and higher productivity growth while lowering the risk of the economy converging to a poverty trap.Centralization and Decentralization, Moral Hazard, Social Capital, Multiple Equilibria, Economic Growth, Competitive Policy

Random Correlation Matrix and De-Noising

In Finance, the modeling of a correlation matrix is one of the important problems. In particular, the correlation matrix obtained from market data has the noise. Here we apply the de-noising processing based on the wavelet analysis to the noisy correlation matrix, which is generated by a parametric function with random parameters. First of all, we show that two properties, i.e. symmetry and ones of all diagonal elements, of the correlation matrix preserve via the de-noising processing and the efficiency of the de-nosing processing by numerical experiments. We propose that the de-noising processing is one of the effective methods in order to reduce the noise in the noisy correlation matrix.correlation matrix, calibration, rank reduction, de-noising, wavelet analysis

Parallel Imports, Drag Price Control and Pharmaceutical Innovation

This paper examines how parallel importation influences pharmaceutical innovation and the welfare of the economy, when crossnational drug price differentials occur not only because of demand elasticity based factors, but also governmental drug price control based factors. By explicitly considering the governmental drug price control baaed factors, this paper shows that parallel importation may enhance pharmaceutical innovation, when the bargaining power of a foreign government is strong and the price elasticity of demand in the foreign market is small. We also show that the increase in R&D induced by parallel imports may even increase the consumer surplus of a country with high demand elasticities and which could face relatively low drug prices, if parallel imports were not allowed.Parallel Imports, Pharmaceutical Innovation, Drug Price Control