Stability of the solutions upon extrapolation in time. Bars indicate the value of χ, which corresponds to the difference between the estimated expression levels averaged over the time points and the expression level extrapolated to τ
(see Eq. 13). The five bars correspond to the five model structures of eqs (5-9). (a) Embryonic time series; τ
corresponds to 3 times the measuring period; (b) full time series; τ
corresponds to the Drosophila life time, i.e. 80 days.