We study large scale collective dynamics of isoscalar type and examine the influence of interactions residual to independent particle motion. It is argued that for excitations which commonly are present in experimental situations such interactions must not be neglected. With respect to dissipation, our results are contrasted with those of wall friction.

PACS numbers: 21.60.Ev, 21.60.Cs, 24.10.Pa, 24.75.+i