function yp = vTau2s_eqn (t, y, p) if y(1) < 0; y(1) = 0; end modt = mod(t,p.per); if (modt <= p.per*p.dc) Ca = p.Ca_level; else Ca=0; end yp = y; yp(1) = (1-y(1))*p.alpha*Ca - y(1)*p.beta;