Mean contrasts extracted from these data were multiplied by a factor of 1.16627 to account for the scaling of scattering contrast with salt concentration (through its effect on the refractive index).
Calibration data (and most other data in this manuscript) were taken at a salt concentration of 100 mM, whereas these data were taken at 500 mM NaCl in order to maintain the open conformation of the non-crosslinked SMM.