Essays on Human Capital Complementarities

The thesis consists of three chapters that study the interplay between skills and health in shaping labour market outcomes. I focus on two distinct but related issues: i) the wage losses among older workers due to work-limiting health conditions, and ii) the long lasting effects of childhood health conditions on human capital formation. Chapter two studies how health conditions among older workers affect their wages depending on the characteristics of their occupations. The U.S. Social Security Act defines disability as the inability due to health conditions to perform physically or mentally demanding tasks. To examine the potentially task-specific nature of work-limiting health conditions, I estimate a wage equation that allows health conditions to have heterogeneous wage returns depending on what kinds of tasks the workers conduct within their occupations. The estimation results, based on a panel dataset of older workers in the U.S., indicate that the magnitude of health-induced wage losses differs substantially across occupations depending on their task characteristics, contrary to the commonly used assumption that health is uniformly valued across occupations. I also show that about 60\% of the health-related wage gaps can be explained by the correlations between health and skills. This chapter further demonstrates that work-limiting health conditions are correlated with the time-varying components of multiple skills. This suggests that econometric models with single-dimensional, time-invariant unobserved heterogeneity may not be fully successful in isolating the influences of the correlations between health and skills. The third chapter investigates the link between childhood health conditions and skill formation. While existing evidence suggests that certain childhood health conditions affect schooling outcomes, little is known as to whether and how such influences persist into labour market skills beyond academic outcomes. By adopting a multidimensional skills/tasks approach, this chapter provides a set of new evidence regarding how childhood health conditions affect skills used in the labour market. To obtain objective measures of childhood health conditions, I exploit medical examinations conducted in the 1958 British National Child Development Study (NCDS). The results point to the importance of childhood health conditions in determining what kinds of occupations individuals pursue in the labour market. In particular, I find that those who had mental health conditions before age 16 tend to select into less cognitive skill demanding jobs while those who had physical health conditions sort into less manual skill demanding jobs. The observed variation in job selections are found as important predictors of the health-related earnings gaps. An important question is whether poor health during childhood influences later outcomes by restricting skill formation, or by mainly affecting future health. To further examine the sources of the earnings gaps associated with childhood health conditions, the fourth chapter develops and estimates a lifecycle model where childhood health conditions can affect formation of skills and health over the life course. The estimated model is used to quantify the relative importance of the multiple channels through which childhood health conditions may affect labour earnings. The results indicate that the most important channel accounting for mental health-related earnings gaps is the skill channel. About 60-65\% of the earnings gaps can be explained by the effects of childhood health conditions on skill formation. The effects of childhood health status on health formation are also found to play important roles

A Prospective Study of Long-term Outcomes in Female Patients with Nonalcoholic Steatohepatitis Using Age- and Body Mass Index-matched Cohorts

In patients with nonalcoholic steatohepatitis (NASH), the prevalence of cirrhosis is higher among women than men, and hepatocellular carcinoma (HCC) develops mainly in the cirrhotic stage among women. However, the long-term outcomes in female patients with NASH have not been fully elucidated, and age, gender and BMI were not simultaneously adjusted in previous studies on the prognosis of NASH. To elucidate the outcomes in female patients with NASH, we prospectively compared NASH patients with advanced fibrosis (advanced NASH) with hepatitis C virus-related advanced fibrosis (advanced CHC) patients and NASH patients with mild fibrosis (mild NASH) using study cohorts that were adjusted for body mass index (BMI) in addition to age. The median follow-up period was 92.5 months. Liver-related complication-free survival was significantly reduced in the advanced NASH group compared to the mild NASH group. No liver-related complications developed in the mild NASH group. The overall survival, liver-related complication- and cardiovascular/cerebrovascular disease-free survival were not significantly different between the advanced NASH and CHC groups. Female patients with NASH and advanced fibrosis may have a less favorable prognosis for liver-related complications than the matched cohorts with NASH and mild fibrosis, but may have a similar prognosis to the matched cohorts with CHC

Freak wave in a two-dimensional directional wavefield with bottom topography change. Part 1. Normal incidence wave

In the propagation and evolution of sea waves, previous studies pointed out that the occurrence of the freak wave height is significantly related to the quasi-resonant four-wave interaction in the modulated waves. From numerical--experimental study over an uneven bottom, the nonlinear effect caused by the bathymetry change also contributes to the occurrence of extreme events in unidirectional waves. To comprehensively analyse the two-dimensional wavefield, this study develops an evolution model for a directional random wavefield based on the depth-modified nonlinear Schrödinger equation, which considers the nonlinear resonant interactions and the wave shoaling the shallow water. Through Monte Carlo simulation, we discuss the directional effect on the four-wave interaction in the wave train and the maximum wave height distribution from deep to shallow water with a slow varying slope. The numerical result indicates that the directional spreading has a dispersion effect on the freak wave height. In a shallow-water environment, this effect becomes weak, and the bottom topography change is the main influencing factor in the wave evolution

THE COMPARISON TO THE CHARACTERISTICS OF THREE-DIMENSIONAL JOINT KINETICS BETWEEN SINGLE LEG AND DOUBLE LEG REBOUND JUMP

The purpose of this study was to clarify the differences between the SRJ and DRJ in terms of three-dimensional joint kinetics for the takeoff leg. Twenty male track and field athletes were performed repeated rebound jump with single leg (SRJ) and double leg (DRJ). Kinematics and kinetics data were recorded using Vicon T20 system (250 Hz) and force platforms (1000 Hz). When comparing a SRJ to a DRJ, the characteristics of the former are as follows: 1) the jump height by a single leg is significantly higher because of the larger hip joint work around the extension-flexion, especially on the abduction-adduction axes; 2) the hip extension and abduction torque is larger; and 3) in the SRJ, the hip abduction torque is larger than the hip extension torque. Therefore, the joint kinetics of the SRJ is characterized by the large hip abduction torque, in addition to the large hip extension torque

Bariatric Surgery on Type 2 Diabetes Mellitus Patients in Japan

Article信州医学雑誌 59(4): 273-279(2011)departmental bulletin pape

Organic Matter Clogging Results in Undeveloped Hardpan and Soil Mineral Leakage in the Rice Terraces in the Philippine Cordilleras

Rice terraces in Cordillera, Philippines, a world cultural heritage site, are threatened by the risk of collapse. It is crucial to manage these rice terraces for their conservation, while simultaneously practicing traditional farming. We examined the soil environment and investigated its effects on rice terrace conservation, by focusing on the hardpan condition; infiltration process, which is related to the collapse of rice terraces; and soil nutrition conditions in these sites. Field survey and soil analysis revealed that in areas where the hardpan was not sufficiently developed and water infiltration was effectively suppressed, organic matter content was significantly high, suggesting organic matter clogging. In these rice terraces, the amounts of P, K, Ca, and Mn were significantly low, showing the mineral leaching under reductive soil conditions. Therefore, hardpan formation, rather than organic matter clogging, is essential for the suppression of infiltration and prevention of potential terrace collapse. Because hardpan formation or organic matter clogging cannot be identified from the surface of flooded rice paddies, it is difficult to identify the influencing factor. Thus, we suggest that the hard soil layer should be checked before the planting season and drainage is allowed after the cropping season in the rainy season