1. School of Business and Research Center for Econophysics, East China University of Science and Technology, Shanghai, 200237China.
2. Department of Mathematics, School of Science, East China University of Science and Technology, Shanghai, 200237China.
3. Department of Management, Technology and Economics, ETH Zurich, Scheuchzerstrasse 7, CH-8092, Zurich, Switzerland.
4. Swiss Finance Institute, c/o University of Geneva, 40 blvd. Du Pont dArve, CH 1211, Geneva, 4Switzerland.