Correlated noise in a logistic growth model

The logistic differential equation is used to analyze cancer cell population, in the presence of a correlated Gaussian white noise. We study the steady state properties of tumor cell growth and discuss the effects of the correlated noise. It is found that the degree of correlation of the noise can cause tumor cell extinction.Comment: 3 pages, 4 figure

Modeling an efficient Brownian heat engine

We discuss the effect of subdividing the ratchet potential on the performance of a tiny Brownian heat engine that is modeled as a Brownian particle hopping in a viscous medium in a sawtooth potential (with or without load) assisted by alternately placed hot and cold heat baths along its path. We show that the velocity, the efficiency and the coefficient of performance of the refrigerator maximize when the sawtooth potential is subdivided into series of smaller connected barrier series. When the engine operates quasistatically, we analytically show that the efficiency of the engine can not approach the Carnot efficiency and, the coefficient of performance of the refrigerator is always less than the Carnot refrigerator due to the irreversible heat flow via the kinetic energy.Comment: 8 pages and 14 figure

Fractional Gaussian noise-induced evolution and transitionin anti-tumor model

Noise induced evolution and transition in an anti-tumor model under immune surveillance are investigated in the presence of additive fractional Gaussian noises. Unlike white Gaussian noise, the Hurst exponent of noise plays a constructive role in the evolution. The noise can also induce the transition. As the noise intensity increases, the noises induced the transition from two states to one state for antipersistent case, whereas the curve always presents a bimodal structure and only the heights of their peaks changed for the persistent case

Directed transport in deformable ratchets

Transport of overdamped Brownian particles in deformable potentials is investigated in the presence of asymmetrically unbiased fluctuations. It is found that the deformation of the potential can strongly affect the directed transport. For small noise strength, the current is not always monotonic function of deformable parameter. For large noise strength, there exists a value of deformable parameter at which the current takes its maximum. Therefore, it is possible to obtain the optimal transport by changing the deformation of the potential

Genotype selection model with two time-correlated white noises

We study the steady state properties of a genotype selection model in the presence of two time correlated Gaussian white noises. Based on the corresponding Fokker-Planck equation the steady state solution of the probability distribution has been investigated. The fluctuation of both the mutation factor and the genetic factor can break the balance of the gene selection. The fluctuation of the genetic factor can facilitate the gene separation which allows us to select one gene-type haploid from a gene group while the fluctuation of the mutation factor impedes the gene separation. Remarkably, the correlation time between the two noises can induce the system to change from two states to one.

Negative differential thermal resistance in coupled rotor lattices

We study heat conduction through one-dimensional homogeneous lattices in the presence of the anharmonic nearest-neighbor interaction without an on-site potential. We observe the occurrence of negative differential thermal resistance (NDTR); i.e., there exists a region of temperature difference where the heat flux decreases as the applied temperature difference increases. The strength of nearest-neighbor interactions has negative effects on the occurrence of NDTR. However, the NDTR regime barely changes with rotation frequency. It is also proven that the on-site potential is not a necessary condition for NDTR. These investigations will contribute to the fabrication of thermal devices where NDTR plays an important role