Received: 4 February 2020
Accepted: 6 April 2020
First Online: 19 April 2020
Ethics approval and consent to participate
: We ensure that this work has been carried out in accordance with the Code of Ethics of the World Medical Association (Declaration of Helsinki) for experiments involving humans, and informed consent was obtained from all participants. The study protocol was approved by the Comprehensive Human Sciences review board at the University of Tsukuba, Japan.
: This is not applicable as the study does not have individual person’s data.
: The authors declared that they have no competing interests.