Text and Data Mining valid from 2019-01-23
First Online: 23 January 2019
Compliance with Ethical Standards
: Hiroko Segawa, Ichiro Kaneko, Yuji Shiozaki, Mikiko Ito, Sawako Tatsumi, and Ken-Ichi Miyamoto each declare no potential conflicts of interest.
: This article contains no studies with human and animal subjects performed by any of the authors.