Particle motion during the compaction of granular matter
  We track particle motions in a granular material subjected to compaction using a laser scattering based imaging method where compaction is achieved through thermal cycling. Particle displacements in this jammed fluid correlate strongly with rearrangments of the Voronoi cells defining the local spatial partitioning about the particles, similar to previous observations of Rahman on cooled liquids. Our observations provide further evidence of commonalities between particle dynamics in granular matter close to jamming and supercooled liquids. 
Steven Slotterback, Masahiro Toiya, Leonard Goff, Jack F. Douglas,   Wolfgang Losert