  We study isovector collective excitations in nuclear matter by employing the
linearized Landau-Vlasov equation with and without a non-Markovian binary
collision term at finite temperature. We calculate the giant dipole resonance
(GDR) strength function for finite nuclei using Steinwedel-Jensen model and
also by Thomas-Fermi approximation, and we compare them for 120Sn and 208Pb
with experimental results.
