Text and Data Mining valid from 2018-05-18
Received: 6 March 2017
Accepted: 26 April 2018
First Online: 18 May 2018
Ethics approval and consent to participate
: The research was ethically approved by the Regional Ethical Review Board (Dnr 736–14) in Gothenburg (Sweden), and followed the ethical considerations of the Helsinki declaration. Written informed consent was obtained from the participants prior to the study.
: The authors declare that they have no competing interests.
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