Dynamical Evolution of Solids Subject to the Drag Force and the   Self-Gravity of an Inhomogeneous and Marginally- Gravitationally Unstable   Disk
  The results of an extensive numerical study of the orbital dynamics of small bodies ranging from micron-sized dust grains to 1 km objects subject to gas drag and also the gravitational attraction of a non-uniform gaseous nebula are presented. The results indicate that it is possible for small bodies to migrate rapidly toward the locations of the maxima of the gas density where the probabilities of collisions and coagulations are enhanced. 
Nader Haghighipour (Carnegie Institution of Washington)