Oscillators continued 2 x=-xtaytx y model for glycolysis y-x y x nullclines a+x a+x x=b fixed point stable or unstable atbiOscillators continued .... y b ay x y x x ay x y 2 2 = − − = − + + & & model for glycolysis 2 2 a x b y a x x y + = + = nullclines: 2 * * a b b y x b + = = fixed point: stable or unstable ? 7