Text and Data Mining valid from 2018-03-30
Received: 25 October 2017
Accepted: 21 March 2018
First Online: 30 March 2018
Compliance with ethical standards
: Nobu Nishiok, Takeshi Ogura, Yoshitaka Kurisu, Miyuki Imanishi, Saori Onda, Wataru Takagi, Tatsushi Sano, Atsushi Okuda, Akira Miyano, Mio Amano, and Kazuhide Higuchi declare that there are no conflict of interest or financial ties to disclose.