PSF in mass photometry
Few Questions:
1) In the 2018 science publication, the PSF is defined as a difference of two concentric 2D Gaussians. There is a parameter T (transmissivity of the mask) that is in this equation. What is the value of T? Is that a constant set by the manufacturer?
2) In the 2020 Nature Comm publication ("Quantifying the heterogeneity of macromolecular machines by mass photometry"), the image processing section does not mention normalizing the ratiometric image. However, this is specified in the 2018 Science paper (i.e subtraction of the mean value from each frame batch). Is this an omission or is normalization no longer done in the latest version of the software?
3) Also in the 2020 Nature Comm publication, the precise functional form of the PSF is not specified to my knowledge. Is the PSF the same as the one in the Science publication. If so, how do the two thresholds (T1,T2) relate to the one specified in the Science publication?
4) In the most recent Nature methods paper ("Mass photometry enables label-free tracking and mass measurement of single proteins on lipid bilayers"), the PSF is a jinc function. Just to make sure, is this PSF specific to dynamic mass photometery? If not, what is the value of the contrast in terms of the fitted values extracted from the jinc function?
Sorry for the long list of questions, but I'm just trying to make sense of the information coming from different publications.