1. University of Granada, Departamento de Matemática Aplicada, Spain
2. IMATI CNR, Pavia, Italy
3. Politecnico of Torino, Italy
4. IMATI CNR, Via A. Ferrata 5/A, 27100 Pavia, Italy
5. University of Granada, Departamento de Matemática Aplicada and Research Unit “Modeling Nature” (MNat), 18071 Granada, Spain