About the Authors

Guo Liu

Affiliation College of Urban and Environmental Sciences, Peking University, Beijing, China

Yi Yin

Affiliation College of Urban and Environmental Sciences, Peking University, Beijing, China

Hongyan Liu

lhy@urban.pku.edu.cn

Affiliation College of Urban and Environmental Sciences, Peking University, Beijing, China

Qian Hao

Affiliation College of Urban and Environmental Sciences, Peking University, Beijing, China

Competing Interests

The authors have declared that no competing interests exist.

Author Contributions

Conceived and designed the experiments: HL. Performed the experiments: GL YY. Analyzed the data: GL YY QH. Contributed reagents/materials/analysis tools: GL YY QH. Wrote the paper: GL HL.