Fig. 9.

The density of infected individuals as a function of β for different values of m. Here $\lambda =0.3,$$\sigma =0.5$$\delta =0.6,$$\mu =0.4$ and $\kappa =0.0$. (a): $\gamma =1$; (b): $\gamma =0.5$; (c): $\gamma =0.25$; (d): $\gamma =0$.