... zÃiÞ=zÃi, with i ¼ 1,. ,9, obtained by integrating the nine-dimensional PTS model with MATLAB’s ode23s ODE suite (solid curves) and with the time measured in milliseconds. The dashed curves are the ... we denote byy, with dimðyÞ¼ny¼ n À nx] are at quasi-steady-state with respect to the instanta-neous values of the remaining state variables [whichwe denote byx, with dimðxÞ¼nx]. ... major advantages ofthis reduced ODE over the full ODE system are, first,that its dynamics are one-dimensional and thus trans-parent and, second, that only the slow timescale ispresent in it,...