1. Bioinformatics Group, Department of Computer Science, and Interdisciplinary Center for Bioinformatics , Universität Leipzig , Härtelstraße 16–18, D-04107 Leipzig , Germany
2. Max-Planck-Institute for Mathematics in the Sciences , Inselstraße 22 , D-04103 Leipzig , Germany
3. Institute for Theoretical Chemistry , University of Vienna , Währingerstraße 17, A-1090 Wien , Austria
4. Facultad de Ciencias , Universidad National de Colombia , Sede Bogotá , Colombia
5. Santa Fe Institute , 1399 Hyde Park Rd. , Santa Fe , NM 87501 , USA