Article History
Received: 16 July 2018
Accepted: 3 August 2018
First Online: 16 August 2018
Ethics approval and consent to participate
: Ethical approval was granted by Institutional Review Board of Thammasat University.(Registry #MTU-EC-OT-0-118/60). A written informed consent was obtained from all the participants in this study.
: Not applicable.
: We declare that none of the authors have any competing interests.
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