Properties of disks and spiral arms along the Hubble sequence
  This paper presents some new statistical correlations between the properties of disks and spiral arms with some physical properties of galaxies. Our results show that the thickness of spiral disks tend to diminish along the Hubble sequence in the sense that disks of Sc galaxies are 40% thinner than disks of Sab-Sb galaxies. Moreover, the thinner disks tend also to be bluer. We also find that there exists a correlation between HI linewidths and arm pattern within each Hubble type, which suggests that the arm shape is partially determined by the mass of a galaxy. Total mass luminosity ratios and total mass surface densities also have correlations with pitch angles, i.e., for disks with lower surface densities and lower total mass luminosity ratios, the pitch angles tend to be greater. 
Jun Ma (National Astronomical Observatories, P.R. China)