1. IMT School for Advanced Studies Lucca, Lucca, Italy
2. University of Tuebingen, Tuebingen, Germany
3. IMT School for Advanced Studies, Lucca, Italy
4. Università degli Studi di Milano Bicocca, Milano, Italy
5. University of Tübingen, Tübingen, Baden-Württemberg, Germany
6. Technical University of Munich, Munich, Germany