Fig. 6.

Contour shows the variation of $R_e$ for different parameter values: a shows the variation of $R_0$ for different values for $\beta$ and ${\delta }_s$, b shows the variation of $R_0$ for different values for $\beta$ and ${\sigma }_1$ and the lower heat map c shows the variation of $R_0$ for different values for $\beta$ and ${\gamma }_1$