Text and Data Mining valid from 2019-11-30
Received: 30 August 2019
Accepted: 29 October 2019
First Online: 30 November 2019
Ethics approval and consent to participate
: The study was approved by the Ethics Committee of the Yamanashi University and performed in accordance with the ethical standards of the Declaration of Helsinki and its later amendments.
: All study participants provided informed written consent prior to their study enrollment.
: The authors declare that they have no competing interests.