Fig. 4.

System (20) undergoes a Pitchfork bifurcation when parameters $({\mathit{\alpha }}_1,{\mathit{\alpha }}_2)$ pass the curve $S$ in Fig. 2. a The origin is locally asymptotically stable when $({\mathit{\alpha }}_1,{\mathit{\alpha }}_2)=(-0.003,-0.003)$ under initial conditions $(0.02,0.000004,0.0002,0.0004,0.0002,0.0004)$ (the black curve) and $(-0.02,-0.000004,-0.0002,-0.0004,-0.0002,0.0004)$ (the blue curve). b System (20) has two locally asymptotically stable nontrivial equilibria when $({\mathit{\alpha }}_1,{\mathit{\alpha }}_2)$ = $(-0.003,0.003)$ with the same initial conditions as a. (Color figure online)