354287.fig.004a
(a)
354287.fig.004b
(b)
354287.fig.004c
(c)
354287.fig.004d
(d)
Figure 4: Numerical simulation of (45) with ; hence (0.347644,  0.0760948,  0.0760948,  4.51674,  0.330353,  0.0765909,  0.0765909,  4.4678) is globally stable. Graphs (a) and (b) illustrate that , and will eventually towards to steady state. Graphs (c) and (d) illustrate that , and will eventually towards to steady state. Initial values are , and .