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 Title: 

            Vertical size-sorting of grains in disks

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 Authors:

          C. Dominik

          C.P. Dullemond

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 Abstract:

          Size-sorting will be an important effect in disks with dramatic consequences on the observable properties of a disk.  Observations at optical, near, and even mid-IR are heavily biased to the disk surface.  Grains with different surface/mass ratios will settle in disks at different speeds and will also show different coupling to turbulent vertical mixing.  We will discuss these effects, their consequences on observable quantities like grains sizes, and try to conclude on how representative the observed upper layers are  for the whole diks population of dust.

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