Minoru Tabata

Sex- and age-related differences in morbidity rates of 2009 pandemic influenza A H1N1 virus of swine origin in Japan.

Background The objective of the present study was to determine whether the morbidity rates of the 2009 pandemic influenza A H1N1 virus (pdmH1N1) varied by age and/or sex. Methods and Findings Retrospective analysis of 2,024,367 cases of pdmH1N1 was performed using the national surveillance data from influenza sentinel points in Japan. The male-to-female morbidity ratios (M/F ratios) in nineteen age groups were estimated as the primary outcome. The M/F ratios for pdmH1N1 influenza were: >1 in age groups <20 years and ≥80 years (p<0.001); <1 in age groups 20–79 years (p<0.001). This data suggests that males <20 years of age may be more likely to suffer from pdmH1N1 influenza than females in the same age categories. When the infection pattern for pdmH1N1was compared with that of seasonal influenza outbreaks between 2000 and 2008, the M/F ratio for pdmH1N1 influenza was higher in ages 3–29 years and lower in ages 40–79 years. Because the present study was based on the national surveillance, it was impossible to estimate the morbidity rate for the Japanese population. It is also likely that the data did not capture asymptomatic or mild infections. Conclusions Although exposure to the pdmH1N1 virus is assumed to be similar in both boys and girls, M/F ratios were >1 in those younger than 20 years. The subsequent reversal of the M/F ratio in the adult generation could be due to several possibilities, including: greater immunity among adult males, more asymptomatic infections among males, less reporting of illness by males, or differences in exposure to the virus and probability of visiting a clinic. These results suggest that the infection and virulence patterns of pdmH1N1 are more complex than previously considered.

Age and gender specific prevalence of HTLV-1

BACKGROUND The seroprevalence of Human T-cell Leukemia Virus Type 1 (HTLV-1) is female predominant despite the higher incidence of Adult T-cell Leukemia (ATL) in males. If the mother-to-child transmission of HTLV-1 is more common for male infants than in female infants, longer exposure to the virus for males may explain the paradoxically higher incidence of ATL. OBJECTIVES To test the hypothesis that the seroprevalence of HTLV-1 is male predominant during adolescence. STUDY DESIGN The presence of HTLV-1 antibody in 272,043 blood samples donated to a regional blood bank in an HTLV-1 high-endemic region was assessed. RESULTS The entire population of female donors had a significantly higher seroprevalence compared to males (2.05% and 1.80%, respectively, p<0.0001). However, compared with male donors, the carrier rate for female donors was lower for the youngest subgroup (16-19 years, p=0.0011); was similar for the next two age subgroups (20-29 years and 30-39 years); and was significantly higher for the last two age subgroups (40-49 years and over 50-64 years, both p<0.0001). In general, older age subgroups led to higher seroprevalence in both genders. CONCLUSIONS HTLV-1 infection is more common for males until after age 20, when male to female sexual transmission becomes likely. This suggests that mother-to-child transmission is more common for males.

Entropy coefficient of determination for generalized linear models

The objective of the present paper is to propose a predictive power measure for generalized linear models (GLMs). First, basic predictive power measures for GLMs are compared with respect to some desirable properties. We propose a generalized coefficient of determination for GLMs, which is referred to as the entropy coefficient of determination (ECD). The advantage of the measure is discussed in the GLM framework. Second, the asymptotic properties of the maximum likelihood estimator of ECD are discussed. Third, ECD is applied to GLMs with polytomous response variables. Finally, discussions and a conclusion to this study are provided.

Existence, uniqueness, and computation of short-run and long-run equilibria of the Dixit-Stiglitz-Krugman model in an urban setting

The Dixit-Stiglitz-Krugman model is studied in an urban setting.The model has a unique short-run equilibrium.The model has a unique long-run equilibrium.Short-run equilibria are obtained numerically. This study analyzes the short-run and long-run equilibria of the Dixit-Stiglitz-Krugman model, without accounting for agriculture. The model, within the branch of New Economic Geography, describes the real wage distribution and worker movements motivated by the disparity in real wages in an urban setting. No restriction is imposed on the total number of locations where economic activities are conducted. We prove that this model has a short-run equilibrium, obtain a sufficient condition for its uniqueness, and construct an iteration scheme to obtain numerical short-run equilibria whose approximation errors are sufficiently small. Moreover, we prove that if the elasticity of substitution and the transport costs are sufficiently large, then the model has a unique long-run equilibrium.

Three predictive power measures for generalized linear models: The entropy coefficient of determination, the entropy correlation coefficient and the regression correlation coefficient

In this paper, three predictive power measures for generalized linear models (GLMs) are compared, and the utility of the entropy correlation coefficient (ECC) and the entropy coefficient of determination (ECD) is demonstrated. First, ECC, ECD and the regression correlation coefficient (RCC) are briefly explained. Second, relationships of the three measures are discussed, and the necessary and sufficient condition under which ECCÂ and RCCÂ are equal is deduced. Third, ECC and ECD are discussed for GLMs with canonical links and polytomous response variables, and an analysis of the effects of factors in GLMs is given. Finally, a discussion of the conclusions of this study is provided.

The Existence and Uniqueness of Global Solutions to the Initial Value Problem for the System of Nonlinear Integropartial Differential Equations in Spatial Economics: The Dynamic Continuous Dixit-Stiglitz-Krugman Model in an Urban-Rural Setting

Assume that economic activities are conducted in a bounded continuous domain where workers move toward regions that offer higher real wages and away from regions that offer below-average real wages. The density of real wages is calculated by solving the nominal wage equation of the continuous Dixit-Stiglitz-Krugman model in an urban-rural setting. The evolution of the density of workers is described by an unknown function of the replicator equation whose growth rate is equal to the difference between the density of real wages and the average real wage. Hence, the evolution of the densities of workers and real wages is described by the system of the nominal wage equation and the replicator equation. This system of equations is an essentially new kind of system of nonlinear integropartial differential equations in the theory of functional equations. The purpose of this paper is to obtain a sufficient condition for the initial value problem for this system to have a unique global solution.

Statistical solution to the capacity problem in direct-sequence code-division multiple-access communication systems

Capacity in the direct-sequence code-division multiple-access (DS/CDMA) communication system was considered according to the code acquisition performance with the conventional serial-search method, because code acquisition needs a difficult operation. Since capacity in DS/CDMA systems is defined by the maximum number of users that can simultaneously transmit their signals with the same carrier frequencies, assuring a larger capacity is very important in DS/CDMA systems with respect to the economy of frequency source. This paper reconsiders the capacity problem through a statistical approach to code acquisition. First, a DS/CDMA system model is reviewed. Second, properties of the counting method for code acquisition are discussed. It is proved that the method can acquire the target users code under any number of interference users that simultaneously transmit their signals, and that the method can guarantee a considerable precision in code acquisition. Third, an observation time necessary for code acquisition is given from a statistical discussion, and the original counting method is modified into a simpler one. It is concluded that the capacity of the DS/CDMA communication system can be set by the ‘bit error-rate-based capacity or signal-to-noise ratio-based capacity’, i.e. ‘post-acquisition-based criterion’, rather than the ‘acquisition-based capacity’.

Existence of a Short-Run Equilibrium of the Dixit-Stiglitz-Krugman Model

Each short-run equilibrium of the Dixit-Stiglitz-Krugman model is defined as a solution to the wage equation when the distributions of workers and farmers are given functions. We extend the discrete nonlinear operator contained in the wage equation as a set-valued operator. Applying the Kakutani fixed-point theorem to the set-valued operator, under the most general assumptions, we prove that the model has a short-run equilibrium.

Existence and Uniqueness of Solutions to the Wage Equation of Dixit-Stiglitz-Krugman Model with No Restriction on Transport Costs

In spatial economics, the distribution of wages is described by a solution to the wage equation of Dixit-Stiglitz-Krugman model. The wage equation is a discrete equation that has a double nonlinear singular structure in the sense that the equation contains a discrete nonlinear operator whose kernel itself is expressed by another discrete nonlinear operator with a singularity. In this article, no restrictions are imposed on the maximum of transport costs of the model and on the number of regions where economic activities are conducted. Applying Brouwer fixed point theorem to this discrete double nonlinear singular operator, we prove sufficient conditions for the wage equation to have a solution and a unique one.

Existence and computation of solutions to the initial value problem for the replicator equation of evolutionary game defined by the Dixit-Stiglitz-Krugman model in an urban setting

An evolutionary game whose payoffs are defined by a spatial economic model.The replicator equation contains an operator mapping an unknown function to a payoff function.We obtain a numerical solution to the initial value problem for this equation.A global solution converges to an equilibrium attained when all workers are concentrated at a point. Consider an evolutionary game whose payoffs are defined as the distribution of real wages. The distribution of real wages is determined by the Dixit-Stiglitz-Krugman model in an urban setting, and workers (players) move toward points that offer higher real wages and away from points that offer below-average real wages. This game is described by the replicator equation whose unknown function denotes the distribution of workers. The growth rate of population contains an operator that maps an unknown function to the distribution of real wages. We prove that if the elasticity of substitution and the transport costs are sufficiently small, then the initial value problem for this equation has a unique global solution. We obtain a numerical solution by making use of an iteration scheme. We prove estimates for approximation error in this numerical solution. Moreover we prove that if workers are concentrated at a point at the initial time, then the global solution converges to a long-run equilibrium attained when all workers are concentrated at the point. The highest growth rate is attained at the point and the pure best reply is given at the point.