Figure 1

Schematic diagram of the negative feedback oscillator model. $x_i$ is the i th molecular species, ${\alpha }_i$ is the decay rate constant, ${\beta }_i$ is the production rate constant, and $K_i$ is the threshold for turning on/off the production of the target molecular species ($i\in \left\{1,2,\dots ,n\right\}$). n is the number of molecular species. $x_i$ activates $x_{i+1}$ ($i\in \left\{1,2,\dots ,n-1\right\}$). $x_n$ represses $x_1$. All molecular species are subject to degradation.