1. Department of Mathematics, Paris Lodron University, Salzburg, Austria
2. Department of Neurology, Christian Doppler Medical Centre, Paracelsus Medical University, Salzburg, Austria
3. Spinal Cord Injury and Tissue Regeneration Centre Salzburg, Paracelsus Medical University, Salzburg, Austria
4. Institute of Medical Biometry and Informatics, University of Heidelberg, Heidelberg, Germany
5. Department of Statistics, University of Kentucky, Lexington, KY, USA