1. Institute for Mathematics and Scientific Computing, University of Graz8010 Graz, Austria
2. Department of Bioengineering, Politecnico di Milano20133 Milano, Italy
3. Department of Electrical and Computer Engineering, Michigan State UniversityEast Lansing, MI 48824, USA
4. Department of Biomedical Engineering, State University of New York at Stony BrookStony Brook, NY 11794, USA