Weights of edges and nodes on food webs which are available from the empirical data hide much information about energy flows and biomass distributions in ecosystem. We define a set of variables related to weights for each species i, including the throughflow Ti, the total biomass Xi, and the...

The highly detailed international trade data among all countries in the world during 1971–2000 shows that the kinds of export goods and the logarithmic GDP (gross domestic production) of a country have an S-shaped relationship. This indicates that all countries can be divided into three stages...

As huge complex systems consisting of geographic regions, natural resources, people and economic entities, countries follow the allometric scaling law which is ubiquitous in ecological, and urban systems. We systematically investigated the allometric scaling relationships between a large number...