van Holde-Weischet integral distribution plots for an ASTFEM simulated velocity experiment of a reversibly self-associating monomer-dimer system with monomer molecular weight of 20 kDa and a frictional ratio of 1.25, equilibrium constant of 1.0, and koff rate of 0.001/sec. Measured at three different loading concentrations covering a 100-fold concentration range, centered on the equilibrium constant [0.1 (filled triangle), 1.0 (open circles), and 10.0 (filled squares), arbitrary concentration units]. The off-vertical shape of the s-value distribution indicates heterogeneity, the shift in s-value with increasing concentration indicates that this system is reversibly self-associating (in contrast to the data shown in Fig. 7.13.7).