  A relevant relation between the dwell time and the density of states for a
three dimensional system of arbitrary shape with an arbitrary number of
incoming channel is derived. This result extends the one obtained by Gasparian
et al. for the special case of a layered one dimensional symmetrical system. We
believe that such a strong relation between the most widely accepted time
related to the dynamics of a particle and the density of states in the barrier
region, one of the most relevant properties of a system in equilibrium, is rich
of physical significance.
