  A general formalism for the study of excitations above equilibrium in Bethe
ansatz solvable models is presented. Nonzero temperature expressions for
dressed energy, momentum, spin and charge are obtained, and it is found that
the dressed spin and charge are in general momentum dependent. For an
electronic model one may only have spin-charge separation at zero temperature
where the ground state is half-filled and has zero magnetisation. Finally, the
excitations of the Hubbard-Shastry models are examined in detail.
