Received: 20 December 2017
Accepted: 5 January 2018
First Online: 20 February 2018
Ethics approval and consent to participate
: The entire study was performed in accordance with the Helsinki declaration; all subjects provided written informed consent (N.O 43/2009, prot 2161). Ethics committee approval was not required.
: Not applicable.
: GP and GT receive indirect support from TomTec Gmbh. All other authors declare no competing interest, financial or otherwise.
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