13-08U

Several factors that lead to changes in the universality class of the phase transition into superconducting or superfluid state are discussed. These factors do not concern the consideration of changes of the phase transition mechanism, as it happens in HTS. In particular, we consider how the phase transition is influenced by structural disorder or presence of additional fluctuating field. We analyze cases when such factors may change the universality class of the three-dimensional ($d=3$) $O(2)$-symmetric model. Superfluidity of liquid helium-4 in porous media or superconductivity at presence of fluctuating magnetic field may serve as physical realizations of such model description. The goal of this paper is to attract readers attention to the non-trivial effects that might be forecasted on the base of the renormalization group analysis of realistic models. Detailed description of these effects is given elsewhere.