Text and Data Mining valid from 2018-01-25
Received: 11 July 2017
Accepted: 8 January 2018
First Online: 25 January 2018
Compliance with ethical standards
: The authors declare that they have no competing interests.
: There was no outside funding or grants received that assisted in this study.
: This study has been performed in accordance with ethical standards concerning investigations in the United States of America.
: For this type of article informed consent is not required.