  Starting from a microscopic t-J like model and a SU(2) spin-charge separation
ansatz, a relativistic continuum gauge lagrangian is obtained in the vicinity
of a nodal point of the Fermi surface. The excitations in the pseudogap phase
are described by topological excitations in the dual model which has a Z_2
global symmetry due to the effect of instantons. Confinement of spinon and
holons emerge from this picture. The adjoint and fundamental strings are
associated with stripes. As the spin gap decreases a local Z_2 symmetry
emerges.
