Effects Of Noise Color And Noise Coupling On Biological System

The effects of noise color and the coupling between noise terms on difference kinds of biological systems are investigated in this paper. The phase transition like phenomenon, the steady state distribution and the transient behavior of the logistic growth model are analyzed. The mean first passage time and the stochastic resonance in a predator-prey model are obtained. The current and the optimized efficiency of the ratchet in an asymmetry periodic external force are discussed. Firstly, the steady state statistical properties of the logistic growth model with colored noise are analyzed when the unified colored noise approximation is applied. It is found that the noise correlation time and the coupling between noise terms can induce first-order-like phase transition and re-entrance phase transition phenomenon. By applying two different kinds of colored noise approximation methods, the concepts of the intensity correlation time and the effective eigenvalue of the time dependent probability distribution function to describe the fluctuations in a laser system can be used to analyze the logistic growth model. It is found that the effects of the noise color and the coupling between noise terms is very important in a logistic growth model. Secondly, the mean first passage time and stochastic resonance in a predator-prey model is studied analytically when a weak periodic signal and coupling between noise terms are included in the system. The effects of noise color and coupling between two noise terms on the mean first passage time and the stochastic resonance in the system are investigated. The effects of other parameters are discussed. Thirdly, the transport phenomenon of Brownian particle induced by noise in a periodic system is investigated when the coupling and multiplicative noise are included in the system. The current and the optimized efficiency are investigated when the forced ratchet is driven by the coupled noise.