Talk 1 Title: Backsplash in dark matter halos Abstract: Recent work has shown that halos in cosmological N-body simulations exhibit a pronounced feature in their density profiles at large radii. I will explain the origin of this newly discovered feature, and describe how it could be used as a ruler to probe cosmology. Talk 2 Title: Probing dark matter substructure using dusty galaxies Abstract: Dusty star forming galaxies are found in large numbers by CMB surveys like SPT and ACT. I will describe how ALMA observations of these galaxies may be used to measure the amount of dark matter substructure that exists in typical galaxy halos. Results from an approved pilot study, scheduled for later this year, should provide an answer to the missing satellites problem.