In this talk new enclosures for the spectra of operators associated with second order Cauchy problems are presented for non-selfadjoint damping. Our new results yield much better bounds than the numerical range of these non-selfadjoint operators for both uniformly accretive and sectorial damping.
(joint work with B. Jacob, Carsten Trunk and H. Vogt)

We study the Daugavet equation
$\parallel Id+T\parallel$ $=1$ $+$ $\parallel T\parallel$
for Lipschitz operators on a Banach space. For this we introduce a substitute for the concept of slice for the case of non-linear Lipschitz functionals and transfer some results about the Daugavet and the alternative Daugavet equations previously known only for linear operators to the non-linear case.