[1] Inst Fis Liquidos & Sistemas Biol UNLP CONICET, RA-1900 La Plata, Argentina
[2] Univ Sao Paulo, Inst Fis Sao Carlos, Sao Carlos, SP, Brazil
[3] Univ Warwick, Math Inst, Gibbet Hill Rd, Coventry CV4 7AL, W Midlands, England
[4] Univ Warwick, Ctr Complex Sci, Coventry CV4 7AL, W Midlands, England
[5] Univ Zaragoza, Inst Biocomputat & Phys Complex Syst BIFI, E-50018 Zaragoza, Spain
[6] Univ Zaragoza, Dept Theoret Phys, E-50018 Zaragoza, Spain
[7] ISI Fdn, I-10126 Turin, Italy
[8] Univ Sao Paulo, Inst Ciencias Matemat & Comp, Sao Carlos, SP, Brazil
[9] Univ Buenos Aires, FCEN, Inst Calculo, Buenos Aires, DF, Argentina
[10] Consejo Nacl Invest Cient & Tecn, Buenos Aires, DF, Argentina