In this paper we prove that a class of non self-adjoint second order differential operators acting in cylinders $Omegatimesmathbb Rsubseteqmathbb R^{d+1}$ have only real discrete spectrum located to the right of the right most point of the essential spectrum. We describe the essential spectrum using the limiting properties of the potential. To track the discrete spectrum we use spatial dynamics and bi-semigroups of linear operators to estimate the decay rate of eigenfunctions associated to isolated eigenvalues.
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