Fig. 3.
Rules for the occupation of the gut by ENC agents. (a) Continuum model rules in which the change in ENC agent density C with any time increment dt in any region χ along the intestine is governed by the diffusion-like drift (in this case linear) of ENC agents into and out of the region plus the generation of new ENC agents by logistic production (proliferation) at a set rate λ. Note that when the value of C reaches carrying capacity Cmax, all change in C becomes entirely due to diffusion-like drift. (b) CA model on a square lattice in which ENC movement is equiprobable on all four directions as long as the site of placement is not occupied (this has an effect similar to the movement term outlined in red in 3a). At a set rate ENC agents can proliferate with progeny placed adjacently at random, as long as the site of placement is not occupied (this has an effect similar to the production term outlined in green in 3a). The outcome of these models is shown in Fig. 4.