  The bosonization and duality rules in three-dimensions are applied to analyze
some features of superfluids and superconductors. The energy of an ensemble of
vortices in a superfluid is recovered by means of a kind of bound which, to
some extent, shares similarity with the Bogomol'nyi bound. In the case of
superconductors, after recasting the partition function in the form of a pure
effective gauge theory, the existence of finite energy vortex solutions is
discussed
