Measurements and System Identification for the Characterization of Smooth Muscle Cell Dynamics

The paper explicitly reports that the LPM noise-only variance is about 30 dB below the FRF estimate and the total variance (noise + nonlinear) is about 10 dB below the FRF estimate, then concludes that when projected back to the output nearly 30% of the system response is due to nonlinearities (Results section, Fig. 9 narrative) . However, the paper does not specify whether those dB offsets are power- or amplitude-based, nor does it show the projection math. Under the standard power-based interpretation consistent with BLA’s variance-additivity y = GBLA u + ys + ny (eq. and discussion) , the correct fraction attributable to nonlinear distortions is about 9% (not 30%). The model solution performs this calculation transparently and is correct on a power basis. The paper’s statement is, at best, ambiguous (likely mixing amplitude-dB with a power fraction) and leaves out key assumptions; hence, the paper is incomplete on this point. Ancillary experimental details (band 0.06–1 Hz, f0 = 0.0781 Hz) align with the model’s context but do not affect the quantitative discrepancy .