Exposure Assessment of Heavy Metals Resulting from Farmland Application of Wastewater Sludge in Tianjin, China: The Examination of Two Existing National Standards for Soil and Farmland-Used Sludge

Land application is one of the major methods of managing municipal sludge in China. The sludge is used for fertilizing and conditioning soil, but due to the high concentration of heavy metals and other chemicals that it contains, improper use of sludge will lead to the contamination of farmland soil. To provide guidance on the application of sludge in China, the Control Standards for Pollutants in Sludge for Agricultural Use (CSPSAU) were enacted, and implemented in 1985. Afterwards, the National Environment Quality Standards for Soil (NEQSS) were also formulated and put into effect in 1996. In this article, these two national standards were examined by means of exposure assessment. The main exposure pathway to humans that was considered was dietary intake of crops grown on the sludge-applied farmland. Five major types of agricultural crops (rice, wheat, tuber roots, vegetables, and fruits) and three groups of exposure population (the urban individual group, the rural sludge-applying individual group, and the rural sludge nonapplying individual group) were assessed. This case study in Tianjin, China, shows the necessity of reexamining the national standards of the CSPSAU and the NEQSS in the context of risk assessment. More comprehensive surveys and monitoring programs assessing heavy metals contained in farmland soils and crop tissues will be necessary for examining the risks to human health.     

Optimal dispatching control of an AGV in a JIT production system

This paper deals with an FMS (Flexible Manufacturing System) in a JIT (Just-In-Time) production system. The FMS consists of m workstations, one dispatching station and a single AGV (Automated Guided Vehicle). Each workstation has an input buffer of limited capacity and its processing times are distributed stochastically. When the processing of a new component starts at the workstation, a withdrawal Kanban attached to it is sent to the dispatching station. The AGV chooses one from workstations whose withdrawal Kanbans are accumulated at the dispatching station, and conveys a component with a withdrawal Kanban from the dispatching station to the workstation. The main purpose of this paper is to find an optimal dispatching policy of the AGV that maximizes the long-run expected average reward per unit time. The problem is formulated as a semi-Markov decision process and an optimal dispatching policy is computed. Numerical experiments are performed to make several comparisons.     

Managing Technological and Environmental Risks in Japan

This paper is primarily concerned with environmental risks arising from utilizing modern technology. Our attention focuses on the interface between policy decisions and regulatory measures. The interface involves not only science and technology but also politics and social values, and perceptions which are deeply rooted in the industrial countries. A case of setting air quality standards and regulatory practices in Japan is studied on the basis of scientific and technological knowledge, economic cost, and subjective judgment of what constitutes an acceptable level of risk or health hazard.     

What are Relevant Work Incentive Models? Shirking Model, Gift Exchange Model, or Reciprocity Model

This empirical study examines the relevance of different work incentive models by distinguishing reciprocity induced by pecuniary and non-pecuniary factors. Although the literature does not present an examination of different models all together but rather specifically examines each model mainly through experimental laboratory games, we study which models are suitable to explain work incentives in real labor markets. Our analyses reveal that overall reciprocity induced by non-pecuniary factors motivates employees well. The shirking model induces effort only if employees face a high level of vulnerability to firing. However, the high level of vulnerability to dismissal invalidates the gift exchange and reciprocity models. These results can complement controlled laboratory experiments, whose results are often restricted in applying to the reality.     

Selection and reproductive success in males of the dragonfly,Orthetrum japonicum (Odonata: Libellulidae)

Reproductive success, copulation success, and mating success were measured for a population of male dragonflies,Orthetrum japonicum. Copulation success explained the greatest variation in reproductive success. The proportion of copulations followed by oviposition was positively correlated with the number of oviposited eggs per mating. Directional selection on four morphological characters was estimated. The effect of selection on correlated traits was comparable to that of direct selection. Directional selection varied between traits and between episodes in a single trait. The probability that the observed directional selection on the four morphological traits was expected under the condition of the selective neutrality of traits was not smaller than 5%.     

Stock return predictability: A factor-augmented predictive regression system with shrinkage method

To predict stock market behaviors, we use a factor-augmented predictive regression with shrinkage to incorporate the information available across literally thousands of financial and economic variables. The system is constructed in terms of both expected returns and the tails of the return distribution. We develop the variable selection consistency and asymptotic normality of the estimator. To select the regularization parameter, we employ the prediction error, with the aim of predicting the behavior of the stock market. Through analysis of the Tokyo Stock Exchange, we find that a large number of variables provide useful information for predicting stock market behaviors.     

Flood Risk Acceptability and Economic Value of Evacuation

The economic value of evacuation and its relationship with flood risk acceptability in Japan were studied by applying the contingent valuation method (CVM). Flood risk acceptability here refers to the extent to which people accept the occurrence of floods, in terms of scale and frequency. The economic value of evacuation refers to people's willingness to pay (WTP) for avoiding evacuation inconvenience because of its inconvenience and the potential for certain losses as a result of evacuation. Our main finding was that over half of the people (56%) who actually evacuated in a real flood situation reported inconvenience. The greatest inconveniences were the shortages of information and food. Evacuation inconvenience can be regarded as an important factor causing the low rate of evacuation in Japan. The WTP for avoiding current inconvenience was approximately half of the estimated economic value of evacuation, implying that the current budget for evacuation is too small and should be increased to improve the conditions of evacuation sites. The economic value of evacuation can be taken into consideration in the risk assessment process in order to evaluate the efficiency of risk reduction measures. Flood risk acceptability and home ownership are two major statistically significantly determinants of the WTP. Considering that those who accept flood risk have a lower WTP for flood risk control (ex ante measures) than those who reject it, it is reasonable to think that there may be a tradeoff between the public WTPs for ex ante or ex post measures.     

Risk Management across the Globe: Insights from a Comparative Look at Sweden, Japan, and the United States

In light of the present day risk controversies such as global warming and hormones in beef, partially caused by a more globalized world, national differences and similarities in how to manage risks become increasingly important. In this brief "perspective" we focus on how risks are managed in three nations, namely Japan, Sweden, and the United States, specifically focusing on the roles of deliberation, risk analysis, and the importance of cultural factors.