Basu A, Joanny J F, Jülicher F, Prost J
Theoretical Condensed Matter Physics Division and Centre for Advanced Research and Education, Saha Institute of Nuclear Physics, 1/AF, Bidhannagar, 700 064, Kolkata (Calcutta), India.
Eur Phys J E Soft Matter. 2008 Oct;27(2):149-60. doi: 10.1140/epje/i2008-10364-9. Epub 2008 Sep 11.
We discuss general features of noise and fluctuations in active polar gels close to and away from equilibrium. We use the single-component hydrodynamic theory of active polar gels built by Kruse and coworkers to describe the cytoskeleton in cells. Close to equilibrium, we calculate the response function of the gel to external fields and introduce Langevin forces in the constitutive equations with correlation functions respecting the fluctuation-dissipation theorem. We then discuss the breakage of the fluctuation-dissipation theorem due to an external field such as the activity of the motors. Active gels away from equilibrium are considered at the scaling level. As an example of application of the theory, we calculate the density correlation function (the dynamic structure factor) of a compressible active polar gel and discuss possible instabilities.
我们讨论了接近平衡态和远离平衡态的活性极性凝胶中噪声和涨落的一般特征。我们使用克鲁泽及其同事建立的活性极性凝胶单组分流体动力学理论来描述细胞中的细胞骨架。在接近平衡态时，我们计算凝胶对外场的响应函数，并在本构方程中引入朗之万力，其相关函数遵循涨落耗散定理。然后我们讨论由于外场（如分子马达的活性）导致的涨落耗散定理的破坏。在标度层面考虑远离平衡态的活性凝胶。作为该理论应用的一个例子，我们计算了可压缩活性极性凝胶的密度相关函数（动态结构因子），并讨论了可能的不稳定性。
