Hideki Takayasu

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We focus on Internet rumors and present an empirical analysis and simulation results of their diffusion and convergence during emergencies. In particular, we study one rumor that appeared in the immediate aftermath of the Great East Japan Earthquake on March 11, 2011, which later turned out to be misinformation. By investigating whole Japanese tweets that(More)
Yukihiro Aiba, Naomichi Hatano, Hideki Takayasu, Kouhei Marumo, Tokiko Shimizu aDepartment of Physics, Aoyama Gakuin University Chitosedai 6-16-1, Setagaya, Tokyo 157-8572, Japan bSony CSL, Higashi-Gotanda 3-14-13, Shinagawa, Tokyo 141-0022, Japan cInstitute for Monetary and Economic Studies, Bank of Japan, Hongoku-cho Nihonbashi 2-1-1, Chuo, Tokyo(More)
We analyze the distribution of income and income tax of individuals in Japan for the fiscal year 1998. From the rank-size plots we find that the accumulated probability distribution of both data obey a power law with a Pareto exponent very close to −2. We also present an analysis of the distribution of the debts owed by bankrupt companies from 1997 to(More)
We propose a new type of stochastic network evolution model based on annihilation, creation, and coagulation of nodes, together with the preferential attachment rule. The system reaches a unique quasistatistically steady state in which the distribution of links follows a power law, lifetime of nodes follows an exponential distribution, and the mean number(More)
To uncover an underlying mechanism of collective human dynamics, we survey more than 1.8 billion blog entries and observe the statistical properties of word appearances. We focus on words that show dynamic growth and decay with a tendency to diverge on a certain day. After careful pretreatment and the use of a fitting method, we found power laws generally(More)
Abstract. To investigate the actual phenomena of transport on a complex network, we analysed empirical data for an inter-firm trading network, which consists of about one million Japanese firms and the sales of these firms (a sale corresponds to the total in-flow into a node). First, we analysed the relationships between sales and sales of nearest(More)
We investigate the economic hubs and authorities of the world trade network (WTN) from 1992 to 2012, an era of rapid economic globalization. Using a well-defined weighted hyperlink-induced topic search (HITS) algorithm, we can calculate the values of the weighted HITS hub and authority for each country in a conjugate way. In the context of the WTN,(More)
We analyze high-resolution foreign exchange data consisting of 20 million data points of USD-JPY for 13 years to report firm statistical laws in distributions and correlations of exchange rate fluctuations. A conditional probability density analysis clearly shows the existence of trend-following movements at time scale of 8-ticks, about 1 minute.