6 Mantegna, R.N. (1991) Levy walks and enhanced diffusion in Milan stock exchange. Physica A 179:232-242 Martinerie, J.,Adam, C., Le Van Quyen, M., Baulac, M., Clemenceau, S., Renault, B., Varela, F.J. (1998) Epileptic seizures can be anticipated by non-linear analysis Nat Med 4:1173-1176 May, R.M. (1