Erratum to: HUGO J DOI 10.1007/s11568-010-9137-y

We apologize for an omission in the Acknowledgements section of this article, which should have read as follows:

Acknowledgments This work was supported by a grant from the Max-Planck Innovation Funds and a grant from the German Federal Ministry of Education and Research, NGFNplus, grant no. PNR-01GS08161-2 (to HHR).