Text and Data Mining valid from 2019-02-08
Received: 28 July 2018
Revised: 9 December 2018
Accepted: 4 January 2019
First Online: 8 February 2019
Compliance with ethical standards
: The scientific guarantor of this publication is Takatoshi Aoki.
: The authors of this manuscript declare no relationships with any companies whose products or services may be related to the subject matter of the article.
: No complex statistical methods were necessary for this paper.
: Informed consent was waived because of phantom study.
: Institutional Review Board approval was not required because of phantom study.
: • experimental• performed at one institution