Text and Data Mining valid from 2019-01-09
Received: 28 October 2018
Accepted: 28 December 2018
First Online: 9 January 2019
Ethics approval and consent to participate
: The study was approved by the Institutional Review Board (IRB) of the Kyoto University, where this study was organized, and it was performed in accordance with the ethical standards in the 1964 Declaration of Helsinki and its later amendments. The IRB waived the need for informed consent from the participants because this study was a retrospective study, represented no more than minimal risk to subjects and would not adversely affect their rights and welfare. Before using collected data into statistic procedures, the identification codes were fully encrypted to preserve anonymity. This study did not include intentional deception and sensitive populations or topics.
: Not applicable.
: The authors declare that they have no competing interests.
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