My research is devoted to the theory of interacting electrons in low dimensional and nanoscale structures. In the past it was focused on the two-dimensional electron gas under the quantum Hall effect conditions. My major contribution to that field was the theoretical prediction, in a joint work with Koulakov and Shklovskii, of stripe and bubble phases at high Landau levels. Subsequently I studied effects of Coulomb interactions and disorder on thermodynamic, spin, and transport properties of one-dimensional conductors. My most recent work is devoted to excitons in semiconductor quantum wells and also to electronic and structural properties of graphene.