Trust,cooperation, and market formation in the U.S. and Japan

Compared with the U.S., Japan is believed to have a collectivist culture that nurtures high trust. Results from laboratory and survey research, however, show that Americans are more likely to trust strangers than are Japanese. Why would trust be lower in a collectivist culture? We use an agent-based computational model to explore the evolutionary origin of this puzzling empirical finding. Computer simulations suggest that higher social mobility in the U.S. may be the explanation. With low mobility, agents rarely encounter strangers and thus remain highly parochial, trusting only their neighbors and avoiding open-market transactions with outsiders. With moderate mobility, agents learn to read telltale signs of character so that they can take advantage of better opportunities outside the neighborhood. However, if mobility is too great, there is too little trustworthiness to make the effort to discriminate worthwhile. This finding suggests that higher mobility in the U.S. may explain why Americans are more trusting than Japanese, but if mobility becomes too high, the self-reinforcing high-trust equilibrium could collapse.     

Establishment of tolerable upper intake levels of calcium in Japan and U.S

Dietary reference intake for Japanese was revised for use from 2000 to 2004. It was included not only the recommended dietary allowances but also new tolerable upper intake levels (UL) . The UL of calcium is 2,500 mg/day and the level has been decided by a model of the risk assessment by lowest observed adverse effect level with uncertain factors such as the sensitivity for individuals. The way how to decide Japanese UL levels has mostly referred to those by American National Academy of Science. Enough calcium intake is necessary for accumulating optimal peak bone mass in the young and also for suppressing the decrease in bone density in the old, however, too much high intake of calcium will have adverse effect on balance of other minerals.