We discuss the evaluation of observables in two-dimensional conformal
field theory using the topological membrane description, We show that
the spectrum of anomalous dimensions can be obtained perturbatively fr
om the topologically massive quantum field theories by computing radia
tive corrections to Aharonov-Bohm scattering amplitudes for dynamical
charged matter fields, The one-loop corrections in the case of topolog
ically massive Yang-Mills theory are shown to coincide with the scalin
g dimensions of the induced ordinary and supersymmetric WZNW models, W
e examine the effects of the dressing of a topologically massive gauge
theory by topologically massive gravity and show that the one-loop co
ntributions to the Aharonov-Bohm amplitudes coincide with the leading
orders of the KPZ scaling relations for two-dimensional quantum gravit
y. Some general features of the description of conformal field theorie
s via perturbative techniques in the three-dimensional approach are al
so discussed.