[en] New results were derived from average level spacings of neutron resonances for the spin dispersion parameter of the nuclear level density, which demonstrated the influence of shell effects, as well as the interplay of nucleon pairing correlations for nuclei in the mass range from ²⁹Si to ²⁴¹Pu. The volume and surface components of the nuclear level density parameter, as well as the shell-damping factor, were determined as, a_v 0.076 ± 0.009 MeV^-1, a_s = 0.180±0.047MeV^-1, and γ₀ = 0.047 ±0.04MeV^-1, respectively. The effective nucleon mass at the Fermi surface is derived as m^*/m = 1.09±0.13. New evidence is presented for a dipole-quadrupole interaction term in the primary E1 transitions of average resonance capture data. This evidence is obtained by testing a proposed generalized Landau Fermi liquid model for spherical and deformed nuclei, which includes the effect of the dipole-quadrupole interaction. The Landau-Migdal interaction constant and the effective nucleon mass, are determined as F₀^' = 1.49 ± 0.08, and m^*/m = 1.04 ± 0.07, respectively. (author)