A temperature dependent bulk viscosity coefficient is used in 3 + 1-dimensional hydrodynamic simulations. I study the effect of the increase of bulk viscosity around the critical temperature on the system dynamics in central Pb+Pb collisions at √ sNN = 2760 GeV. With increasing bulk viscosity the lifetime of the system increases slightly. Also the shape of the freeze-out hypersurface changes, the outer layers of the fireball live longer. This effect causes a small reduction of the ratio of two interferometry radii Rout/R side , improving the agreement with experimental data.

An extended time-dependent Hartree-Fock theory which includes the effects of nucleonnucleon collisions is presented and applied to the small-amplitude quadrupole motions of 160 and 4~The collision term of the theory includes not only the Born term but also higher-order terms. It is found that the higher-order terms are essential to the damping of the motions.

Head-on collisions of 16 Oϩ 16 O are calculated using an extended version of the time-dependent Hartree-Fock theory known as the time-dependent density-matrix theory ͑TDDM͒. TDDM deals with both one-body and two-body dissipation in a quantum-mechanical way. A newly developed TDDM code, which includes spin-orbit force in a mean field, is used. It is found that the threshold energy above which the colliding nuclei do not fuse increases due to two-body dissipation. Head-on collisions of 22 Oϩ 22 O are also calculated to investigate the effects of two-body collisions in exotic nuclei. In contrast to the case of 16 Oϩ 16 O, no additional dissipation due to two-body collisions is found in the head-on collisions of 22 Oϩ 22 O.