Fig 5.

Time-dependent clearance of bacteria (sum of susceptible and persister bacteria) using a periodic application of biocide. The inset shows the same curves for times between 20 and 40 h to emphasize the difference in the survival curves. Notice that the discontinuous approach has a lower total bacterial concentration at various times, even though the value of the objective functional is higher. Each method clears the bacteria; however, the optimal control has a lower value of the objective functional, J (namely, 5.09 compared with 9.83).