Funding for this research was provided by:
National Natural Science Foundation of China (31670473)
the Hundred-Talent Program of the Chinese Academy of Sciences
Article History
Received: 26 October 2017
Accepted: 5 March 2018
First Online: 15 March 2018
Authors’ contributions
: J. Z and S.Y.L conceived and designed the analysis. S.Y.L supervised the research. J.Z mined data and carried out data analyses. J.Z and S.Y.L wrote the manuscript. R.Z.D and C.S.J commented on the manuscript. All authors read and approved the final manuscript.