1. São Carlos Institute of Physics, University of São Paulo, São Carlos - SP, PO Box 369, 13560-970, Brazil
2. Institute of Mathematics and Computer Science, University of São Paulo, USP, Avenida Trabalhador São-Carlense, 400, 13566-590, São Carlos, SP, Brazil
3. Institute for Complex Systems and Mathematical Biology, University of Aberdeen, AB24 3UE, Aberdeen, UK