Received: 12 January 2020
Accepted: 24 February 2020
First Online: 6 March 2020
Compliance with ethical guidelines
: L. Stålesen Ramfjord, E. Hertenstein, K. Fehér, C. Mikutta, C. Schneider, C. Nissen and J.G. Maier declare that they have no competing interests.
: For this article no studies with human participants or animals were performed by any of the authors. All studies performed were in accordance with the ethical standards indicated in each case.