Unbiased Rare Event Sampling in Spatial Stochastic Systems Biology Models Using a Weighted Ensemble of Trajectories
Fig 10
Steady-state estimate of time to produce five P2.
The last event in the complex signaling network of Fig 6 is the production of P2. Using a steady-state approach, weighted ensemble is able to estimate the mean time to producing 5 molecules of P2 as approximately 5,000 seconds. The graph shows the probability flux arriving at the target state (left axis) in each iteration (points), and a running average of that flux computed from the most recent 50% of the data (lines). The mean time to reach the target state (right axis) is obtained via the Hill relation (Eq 1), as the inverse of the steady-state flux. Note that during most iterations, zero weight reaches the target state, as evidenced by the nearly continuous band of points at the bottom of the figure. The running average of the flux is dominated by these uneventful iterations, and hence is less than the nonzero instantaneous values.