Text and Data Mining valid from 2017-08-19
Received: 18 July 2017
Accepted: 10 August 2017
First Online: 19 August 2017
Compliance with ethical standards
: The authors declare that they have no conflict of interest.
: All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. For this type of study formal consent is not required.
: Informed consent was obtained from all individual participant included in the study.