The calculated goodness-of-fit measure R2 between numerical data obtained with linear model (i.e. model with σL = const.) and nonlinear model (i.e. model with σL(E)) and in vivo data. σL1(E) and σL2(E) stand for the smoothed Heaviside relationships σL(E) with conductivity increase factor (due to electroporatoion) of two and three, respectively.