  For a variety of quantum dots, the widths of different single-particle levels
may naturally differ by orders of magnitude. In particular, the width of one
strongly coupled level may be larger than the spacing between other, very
narrow, levels. We found that in this case many consecutive Coulomb blockade
peaks are due to occupation of the same broad level. Between the peaks the
electron jumps from this level to one of the narrow levels and the transmission
through the dot at the next resonance essentially repeats that at the previous
one. This offers a natural explanation of the salient features of the behavior
of the transmission phase in an interferometer with a QD. The theory of this
effect will be reviewed with special emphasis on the role of the interactions.
New results on the dot-charging measurements and the fine structure of
occupation switchings will be presented, accompanied by the unified description
of the whole series of CB peaks caused by a single broad level. We then discuss
the case where the system approaches the Kondo regime.
