Figure 6.

The effects of width of threshold window on the durations of drug-on (or drug-off) and number of drug-on/off switches. The parameters are fixed as those in Table 1 with η_RT = η_{P I} = 0.6. (A–B) We fixed the width of threshold window, i.e., let C^TH − C_TH be a constant as 300 μl⁻¹, and C_TH increases from 200 to 600 μl⁻¹; (C–D) We fixed the upper threshold value C^TH as 700 μl⁻¹ and let the lower threshold value C_Th vary from 200 to 600 μl⁻¹; (E–F) We fixed the lower threshold value C_TH as 200 μl⁻¹ and let the upper threshold value C_Th increase from 300 to 700 μl⁻¹.