2,373 research outputs found
Kosiorek, Thomas M. interview
No full textOral History interview of Thomas M. Kosiorek. Interview conducted by Gabrielle Hanke and Roy McKinney
Netzgebundene Wärmeversorgung : Anregungen für Kommunen und andere Akteure
No full textNETZGEBUNDENE WÄRMEVERSORGUNG - ANREGUNGEN FÜR KOMMUNEN UND ANDERE AKTEURE
Netzgebundene Wärmeversorgung - Anregungen für Kommunen und andere Akteure / Hanke, Thomas (Rights reserved) (-
Aktivitäten des Bundes, der Länder und der Kommunen und Handlungsfelder zur Gebäudesanierung
No full textAKTIVITÄTEN DES BUNDES, DER LÄNDER UND DER KOMMUNEN UND HANDLUNGSFELDER ZUR GEBÄUDESANIERUNG
Aktivitäten des Bundes, der Länder und der Kommunen und Handlungsfelder zur Gebäudesanierung / Hanke, Thomas (Rights reserved) (-
Codimension two index obstructions to positive scalar curvature
No full textWe derive a general obstruction to the existence of Riemannian metrics of positive scalar curvature on closed spin manifolds in terms of hyper-surfaces of codimension two. The proof is based on coarse index theory for Dirac operators that are twisted with Hilbert C -module bundles. Along the way we give a complete and self-contained proof that the minimal closure of a Dirac type operator twisted with a Hilbert C -module bundle on a complete Riemannian manifold is a regular and self-adjoint operator on the Hilbert C -module of L-2-sections of this bundle. Moreover, we give a new proof of Roe's vanishing theorem for the coarse index of the Dirac operator on a complete non-compact Riemannian manifold whose scalar curvature is uniformly positive outside of a compact subset. This proof immediately generalizes to Dirac operators twisted with flat Hilbert C -module bundles
Lipschitz rigidity for scalar curvature
No full textLet M be a closed smooth connected spin manifold of even dimension n , let g be a Riemannian metric of regularity W^{1,p} , p > n , on M whose distributional scalar curvature in the sense of Lee–LeFloch is bounded below by n(n-1) , and let f \colon (M,g) \to \mathbb{S}^n be a 1 -Lipschitz continuous (not necessarily smooth) map of nonzero degree to the unit n -sphere. Then f is a metric isometry. This generalizes a result of Llarull (1998) and answers in the affirmative a question of Gromov (2019) in his Four lectures . Our proof is based on spectral properties of Dirac operators for low regularity Riemannian metrics and twisted with Lipschitz bundles. We argue that the existence of a nonzero harmonic spinor field forces f to be quasiregular in the sense of Reshetnyak, and in this way connect the powerful theory for quasiregular maps to the Atiyah–Singer index theorem
Homotopy groups of the moduli space of metrics of positive scalar curvature
No full textWe show by explicit examples that in many degrees in a stable range the homotopy groups of the moduli spaces of Riemannian metrics of positive scalar curvature on closed smooth manifolds can be non-trivial. This is achieved by further developing and then applying a family version of the surgery construction of Gromov–Lawson to certain nonlinear smooth sphere bundles constructed by Hatcher
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