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 Title:  Review: disk evolution and lifetimes
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 Authors:
          Lee Hartmann, CfA

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 Abstract:
          I will review observations of the evolution of disk dust emission and mass accretion.
          As has been recognized for over a decade, timescales for the disappearance of
          small dust in the inner disk and the cessation of disk accretion are similar, a few
          to 10 Myr, with a wide range of outcomes for individual objects.  Some, but not all,
          of this variation in evolutionary timescales is probably due to the presence of binary
          (or multiple) companions.  I will offer a few conjectures concerning the mechanisms
          of disk evolution.

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