1. Department of Mathematics and Computer Science, University of Catania, 95121 Catania, Italy
2. Department of Educational Sciences, Section of Psychology, University of Catania, 95121 Catania, Italy
3. Azienda Sanitaria Provinciale di Catania, 95100 Catania, Italy
4. Center of Excellence for the Acceleration of Harm Reduction (CoEHAR), University of Catania, 95121 Catania, Italy