  We consider the Nernst effect in the normal state of the underdoped cuprate
superconductors, where recent quantum oscillation experiments have indicated
the existence of Fermi surface pockets and quasiparticle ambipolarity in the
excitation spectrum. Using an ambipolar d-density wave model for the pseudogap,
we predict a peak in the Nernst coefficient with decreasing temperature below
the pseudogap temperature. The existence of the peak and its sign, which we
predict to be the same as that due to mobile vortices in a superconductor,
result from the dominance of the electron pocket at low temperatures, as has
been observed in recent Hall experiments.
