  Maldacena's duality between conformal field theories and supergravity is
applied to some conformal invariant models with 8 supercharges appearing in the
F-theory moduli space on a locus of constant coupling. This includes Sp(2N)
gauge theories describing the worldvolume dynamics of D3-branes in the presence
of D7-branes and an orientifold plane. Other examples of this kind are models
with exceptional global symmetries which have no perturbative field theory
description. In all these cases the duality is used to describe perturbations
by primary marginal and relevant operators.
