Fig. 4

Stochastic simulations along three trajectories in inducer concentration space. a Schematic plot of three trajectories parametrized using the parameter 0 ≤t≤1, ie. t is the fractional displacement traversed by a trajectory. b Histogram of the trajectory along and inside of the bistable region. c Plot along the horizontal trajectory of increasing [IPTG]. d Plot along the vertical trajectory of increasing [DOX]. Each histogram bin corresponds to the normalized count that the difference between the numbers of the LacI and TetR active species had a particular value during the time course of the simulation (10⁷ s). The histograms are horizontal and the bin count represented with colour on a linear scale, normalized to the largest bin among all histograms on the plot. The y-axis represents t, the position along the trajectory. The areas tinted grey indicate regions of monostability, while the non-tinted indicate regions of true bistability