Pratap P, Palit A, Lipson E D
Biophys J. 1986 Oct;50(4):645-51. doi: 10.1016/S0006-3495(86)83504-4.
The light-growth response of Phycomyces has been studied with the sum-of-sinusoids method of nonlinear system identification (Victor, J.D., and R.M. Shapley, 1980, Biophys. J., 29:459). This transient response of the sporangiophore has been treated as a black-box system with one input (logarithm of the light intensity, I) and one output (elongation rate). The light intensity was modulated so that log I, as a function of time, was a sum of sinusoids. The log-mean intensity was 10(-4) W m-2 and the wavelength was 477 nm. The first- and second-order frequency kernels, which represent the linear and nonlinear behavior of the system, were obtained from the Fourier transform of the response at the appropriate component and combination frequencies. Although the first-order kernel accounts for most of the response, there remains a significant nonlinearity beyond the logarithmic transducer presumed to occur at the input of the sensory transduction chain. From the analysis of the frequency kernels, we have derived a dynamic nonlinear model of the light-growth response system. The model consists of a nonlinear subsystem followed by a linear subsystem. The model parameters were estimated from a combined nonlinear least-squares fit to the first- and second-order frequency kernels.
利用非线性系统辨识的正弦和方法（Victor, J.D., 和R.M. Shapley, 1980, Biophys. J., 29:459）研究了毛霉的光生长响应。孢子囊柄的这种瞬态响应被视为一个黑箱系统，有一个输入（光强的对数，I）和一个输出（伸长率）。对光强进行调制，使得作为时间函数的log I是正弦之和。对数平均强度为10(-4) W m-2，波长为477 nm。从响应在适当的分量频率和组合频率处的傅里叶变换获得代表系统线性和非线性行为的一阶和二阶频率核。虽然一阶核占了大部分响应，但在假定发生在感觉转导链输入处的对数换能器之外仍存在显著的非线性。通过对频率核的分析，我们推导了光生长响应系统的动态非线性模型。该模型由一个非线性子系统和一个线性子系统组成。模型参数通过对一阶和二阶频率核的组合非线性最小二乘拟合进行估计。
