Funding for this research was provided by:
the National Nature Science Foundation of China (71490735)
Article History
Received: 12 June 2018
Accepted: 14 November 2018
First Online: 14 December 2018
Ethics approval and consent to participate
: Ethical approval was obtained from the Ethics Committee for Medical Research at the School of Public Health, Fudan University. All participants provided written consent to participate.
: Not applicable.
: The authors declare that they have no competing interests.
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