Figure 1.

Graphic illustration of the two equations that, when combined, produce the non-linear growth response curve. The hyperbolic equation F_CU(t) can be regarded as a 'catch-up' equation, (by multiplying with the individual parameter M_Model) asymptotically modulating individual amplitude with time. The "1" on the y-axis gives the asymptotic value of the F_CU(t), and the Equation F_BG(t) can be interpreted as a 'baseline growth' equation that introduces a delayed general growth response with a greater relative impact on individuals with low levels of catch-up growth than on individuals with high levels of catch-up growth.