Frances, D
Sharma, N
Pofahl, R
Maneck, M
Behrendt, K
Reuter, K
Krieg, T
Klein, C A
Haase, I
Niemann, C
Article History
Received: 22 July 2014
Revised: 28 October 2014
Accepted: 19 December 2014
First Online: 9 February 2015
Competing interests
: The authors declare no conflict of interest.