Figure 6.

Time curve of the external stimulus u defined in (16) and $\tilde{u}$ defined in (15) with $\tilde{t}=160$ and $\tilde{\phi }=\pi$, of M calculated from the model (1) to (5), of $\tilde{M}$ calculated by an analogous model like (1) to (5) where (2) is replaced by (14) with $\tilde{\alpha }=0.3$, $\beta =2$, $\delta =0.4$ and of $M^u$ calculated from (1) to (5) where (2) is replaced by (8) with $\alpha =1$ for (16) with $\phi =0$. Units and dimensions: abscissa t: time in hours, ordinate U: amount of substance (M, $M^u$, $\tilde{M}$ mRNA, u intensity of illumination, $\tilde{u}$ intensity of signals of receptors stimulated by food intake).