Plots of empirical models

Gamma Profiles These profiles follow the form c (f) = yt-0 exp (—fit), which is reported in the literature as the gamma-function model [244], This model was used to fit pharmacokinetic data empirically [245,246]. Differentiating with respect to time, we obtain 

In the three profiles above, the coefficient 7 is set according to the initial conditions. For instance, if c(to) = cq at to 0, 7 is equal to 

The linear and x-semilogarithmic plots are uninformative for such decisions. 

In a more realistic context, the observed data usually decay according to a sum 

When the real process generates power-law data, alternatively a sum of exponentials and power function models may be used. But  

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