Funding for this research was provided by:
Shanghai Pujiang Program (14ZS084)
Institutes of Shanghai Municipal Education Commission (14ZS084)
Received: 23 January 2017
Accepted: 28 January 2018
First Online: 12 February 2018
Ethics approval and consent to participate
: This study was approved by the ethics committees of the Second Military Medical University. A complete survey description was first presented to the participants. Informed written consent, together with oral approvals, was obtained before the testing session according to the Declaration of Helsinki.
: Not applicable.
: The authors declare that they have no competing interests.
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