Resolvent expansions and continuity of the scattering matrix at embedded   thresholds: the case of quantum waveguides
  We present an inversion formula which can be used to obtain resolvent expansions near embedded thresholds. As an application, we prove for a class of quantum waveguides the absence of accumulation of eigenvalues and the continuity of the scattering matrix at all thresholds. 
S. Richard and R. Tiedra de Aldecoa
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