  We calculate the one-loop Yukawa couplings and threshold corrections for
supersymmetric local models of branes at singularities in type IIB string
theory. We compute the corrections coming both from wavefunction and vertex
renormalisation. The former comes in the IR from conventional field theory
running and in the UV from threshold corrections that cause it to run from the
winding scale associated to the full Calabi-Yau volume. The vertex correction
is naively absent as it appears to correspond to superpotential
renormalisation. However, we find that while the Wilsonian superpotential is
not renormalised there is a physical vertex correction in the 1PI action
associated to light particle loops.
