  We discuss a new method for obtaining the WKB approximation to the Dirac
equation with a scalar potential and a time-like vector potential. We use the
WKB solutions to investigate the scaling behavior of a confining model for
quark-hadron duality. In this model, a light quark is bound to a heavy di-quark
by a linear scalar potential. Absorption of virtual photons promotes the quark
to bound states. The analog of the parton model for this case is for a virtual
photon to eject the bound, ground-state quark directly into free continuum
states. We compare the scaling limits of the response functions for these two
transitions.

High Energy Physics - Phenomenology