Funding for this research was provided by:
Deutsche Forschungsgemeinschaft (SCHL 1844/2-1, SCHL 1844/2-2)
Technische Universität Hamburg (i3)
Received: 11 January 2020
Accepted: 30 June 2020
First Online: 22 July 2020
Compliance with ethical standards
: The authors M. Gromniak, N. Gessert, T. Saathoff and A. Schlaefer declare that they have no conflict of interest.
: This article does not contain any studies with human participants or animals.
: Not applicable.