  In weakly bound exotic nuclei, number of excited bound states or narrow
resonances is small and, moreover, they couple strongly to the particle
continuum. Hence, these systems should be described in the quantum open system
formalism which does not artificially separate the subspaces of (quasi-) bound
and scattering states. The Shell Model Embedded in the Continuum provides a
novel approach which solves this problem. Examples of application in sd-shell
nuclei will be presented.
