About the Authors

Jianhua Xu

Affiliations College of Environmental Sciences and Engineering, Peking University, Beijing, P. R. China, Center for Crisis Management Research, School of Public Policy and Management, Tsinghua University, Beijing, P. R. China

Zongchao Peng

pengzch@mail.tsinghua.edu.cn

Affiliation Center for Crisis Management Research, School of Public Policy and Management, Tsinghua University, Beijing, P. R. China

Competing Interests

The authors have declared that no competing interests exist.

Author Contributions

Conceived and designed the experiments: JX ZP. Performed the experiments: ZP. Analyzed the data: JX. Contributed reagents/materials/analysis tools: ZP. Wrote the paper: JX ZP.