  We review our recent work on the low-energy actions and the realizations of
strong-weak coupling dualities in non-perturbative phases of compact
antisymmetric tensor field theories due to p-brane condensation. As examples we
derive and discuss the confining string and confining membrane actions obtained
from compact vector and tensor theories in 4D. We also mention the relevance of
our results for the description of the Hagedorn phase transition of finite
temperature strings.
