Fig. 8.

Distribution of displacement hysteresis coefficient S_hyster. The ratio R(t)/R(0) displays a hysteretic character over a breathing cycle, and a measure of this hysteresis is defined as the ratio S_hyster = A_hyster/A_total. (a) Case without muscle content within the ring (m = 0): the hysteretic loops are clockwise (considered positive) since displacements are larger during inspiration, and diminish toward the external boundary; (b) Case m = 1: the overall hysteretic muscle characteristic is dominant and the surface A_hyster is negative (see Fig. 7(b)).