Christiane Tretter
On the spectrum of the magnetohydrodynamic mean-field alpha^2-dynamo operator.
Mon, 04/05/2010 - 15:01 — SomNambulAuthors: Christiane Tretter, Uwe Guenther, Heinz Langer
Subjects: Mathematical Physics
AbstractThe existence of magnetohydrodynamic mean-field alpha^2-dynamos with
spherically symmetric, isotropic helical turbulence function alpha is related
to a non-self-adjoint spectral problem for a coupled system of two singular
second order ordinary differential equations. We establish global estimates for
the eigenvalues of this system in terms of the turbulence function alpha and
its derivative alpha'. They allow us to formulate an anti-dynamo theorem and a
non-oscillation theorem.Bounds on the spectrum and reducing subspaces of a J-self-adjoint operator.
Tue, 09/08/2009 - 12:16 — SomNambulAuthors: Sergio Albeverio, Alexander K. Motovilov, Christiane Tretter
Subjects: Spectral Theory
AbstractGiven a self-adjoint involution J on a Hilbert space H, we consider a
J-self-adjoint operator L=A+V on H where A is a possibly unbounded self-adjoint
operator commuting with J and V a bounded J-self-adjoint operator
anti-commuting with J. We establish optimal estimates on the position of the
spectrum of L with respect to the spectrum of A and we obtain norm bounds on
the operator angles between maximal uniformly definite reducing subspaces of
the unperturbed operator A and the perturbed operator L.Bounds on the spectrum and reducing subspaces of a J-self-adjoint operator.
Tue, 09/08/2009 - 12:16 — SomNambulAuthors: Sergio Albeverio, Alexander K. Motovilov, Christiane Tretter
Subjects: Spectral Theory
AbstractGiven a self-adjoint involution J on a Hilbert space H, we consider a
J-self-adjoint operator L=A+V on H where A is a possibly unbounded self-adjoint
operator commuting with J and V a bounded J-self-adjoint operator
anti-commuting with J. We establish optimal estimates on the position of the
spectrum of L with respect to the spectrum of A and we obtain norm bounds on
the operator angles between maximal uniformly definite reducing subspaces of
the unperturbed operator A and the perturbed operator L.
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