Examples of very unstable linear partial functional differential   equations
  We consider the examples of partial functional differential equations with delay in the Laplacian. First of these equations is linear parabolic equation, the second one is linear hyperbolic equation, third equation is perturbed hyperbolic equation with delay. We show that there are the sequence of eigenvalues in both cases with real parts tends to plus infinity. 
R. S. Ismagilov, N. A. Rautian, V. V. Vlasov
math.AP