Transitions induced by time delays and cross-correlated sine-Wiener noises in a tumor-immune system interplay

A model of tumor-immune system interplay with time delays and cross-correlated sine-Wiener noises is investigated by numerical simulations for the stationary probability distribution (SPD) and stationary mean value (st) of tumor cell population. Results show that (i) the structure of the SPD transfers from bimodal to unimodal as the reaction time (tau(alpha)) of the cell population to environmental constraints increases; (ii) conversely, as the time (tau(beta)) of immune system to develop specific immune competence and the correlation time (tau) of noises increase, the structure of the SPD transfers from unimodal to bimodal; (iii) as the cross-correlated intensity (lambda') between noises increases, the transitions induced by tau are suppressed. (C) 2011 Elsevier B.V. All rights reserved.