Abstract: We consider generalized Schroedinger operators
with an attractive delta-type interaction supported by an infinite
curve with no cusps and self-intersections which is asymptotically
straight in a suitable sense. We show that unless the curve is a
straight line, the operator has at least one isolated eigenvalues
below the threshold of the essential spectrum. For more details see
P. Exner and T. Ichinose, J. Phys. A34 (2001), 1439-1450,
and also math-ph/0001015.