On the Discrete Spectrum of Generalized Quantum Tubes
  In this paper, we study the spectrum of quantum tubes. Under certain intrinsic assumptions of the asymptotically flat submanifold of the Euclidean space, we prove the existence of the ground state of the quantum tube. The work is a generalization of Duclos, Exner and Krejcirik (CMP, 223(1), 13-28, 2001) and ourselves(math.DG/0402252). 
Christopher Lin and Zhiqin Lu