The thick black curve is the numerically-integrated solution to the mass action equations (49a)–(49d). The leftmost dashed vertical line corresponds to tc1, and the rightmost dashed vertical line corresponds to . The lower dotted horizontal line corresponds to the scaled characteristic value . The constants (without units) used in the numerical simulation are: , , , k1 = 0.01, k2 = 1, k3 = 10, k−3 = 1, k4 = 100 and k−1 = 1. Time has been mapped to the t∞ scale: t∞(t) = 1 – 1/ln[t + exp(1)], and c2 has been numerically scaled by its maximum value.