Temperature dependence of the energy of a vortex in a two-dimensional   Bose gas
  We evaluate the thermodynamic critical angular velocity Omega_c(T) for creation of a vortex of lowest quantized angular momentum in a strictly two-dimensional Bose gas at temperature T, using a mean-field two-fluid model for the condensate and the thermal cloud. Our results show that (i) a Thomas-Fermi description of the condensate badly fails in predicting the particle density profiles and the energy of the vortex as functions of T; and (ii) an extrapolation of a simple Thomas-Fermi formula for Omega_c(0) is nevertheless approximately useful up to T = 0.5 T_c. 
K.K. Rajagopal, B. Tanatar, P. Vignolo and M.P. Tosi (SNS Italy,   Bilkent University)