Graph of the capture probability P
versus the ratio of the cell to obstacle radius a/R. for (a) a non-absorbing obstacle (b) a perfectly absorbing obstacle. The parameter values are all set to unity with the exception of C0, which has value 10. Notice that for the second case only cells larger than a certain critical size are captured. The data for these plots were obtained from theory (green) and simulations (blue, red) for (a). The blue curve is computed using the gradient in the middle of the cell and the red curve is computed using the gradient across its body. The data for (b) are from simulations only, with the green curve representing data with the central gradient and the blue curve representing data using the gradient across the cell's body.