  It is shown in this paper that for open systems, states which are localized
in space, discrete in energy, and embedded in the continuum of extended states,
can be sustained by low-dimensional and channeled leads. These states have an
origin different from that of analogous states discussed by J. von Neumann and
E. Wigner [Phys. Z., vol. 30, 465 (1929)]. A few representative systems are
discussed. These states cause, for example, infinitely sharp Fano resonance in
transport when they are marginally destroyed.
