1. School of Mathematics and Physics, University of Science and Technology Beijing , Beijing 100083 , China
2. Department of Statistics and Financial Mathematics , School of Mathematics, , Guangzhou 510641 , China
3. South China University of Technology , School of Mathematics, , Guangzhou 510641 , China
4. Shenwan Hongyuan Securities Co. Ltd. , Shanghai 200031 , China
5. School of Mathematics, Shandong University , Jinan 250100 , China
6. Department of Ocean Science and Engineering, Southern University of Science and Technology , Shenzhen, 518055 , China
7. Department of Quantitative and Computational Biology, University of Southern California , California, 90007 , USA