Funding for this research was provided by:
China National Natural Science Foundation (71761130083)
Received: 12 April 2021
Accepted: 17 August 2021
First Online: 30 August 2021
: The study protocol was approved by the Institutional Review Board of Peking University, Beijing, China. All participants gave written consent after being informed to the aim of the survey and their rights to refuse to participate.
: Not applicable.
: The author reports no conflicts of interest in this work.