We study how initial network structure affects the evolution of cooperation in a spatial prisoner’s dilemma game. The network structure is characterized by various statistical properties. Among those properties, we focus on the variance of the degree distribution, and inquire how it affects...

Social phenomena are affected by the structure of networks consisting of personal relationships. In the present paper, the diffusion of information among people is examined. In particular, the relationship between the network structure and the dynamics is studied. First, several networks are...

The decision-making process that precedes the introduction of a new energy system should strive for a balance among human security, environmental safeguards, energy security, proliferation risk, economic risks, etc. For nuclear energy, the Fukushima Daiichi nuclear disaster (Fukushima disaster)...

After the Fukushima nuclear disaster, a reassessment of the energy system is needed in order to include such aspects as human security and resilience. More open and careful discussions are needed concerning the various risks and uncertainties of future energy options, both in Japan and globally....