We consider smooth actions of totally disconnected groups on simplicial complexes and compare different equivariant cohomology groups associated to such actions. Our main result is that the bivariant equivariant cohomology theory introduced by Baum and Schneider can be described using equivariant periodic cyclic homology. This provides a new approach to the construction of Baum and Schneider as...

We review topologically Nistor’s computation of the homogeneous part of the periodic cyclic cohomology of crossed products Γ⋉A of torsion-free discrete groups Γ with a complex Γ-algebra A. We use periodic cyclic cohomology associated to bornological algebras. Let G be a complex connected semisimple Lie group and B be a minimal parabolic subgroup of G. Applied to torsion-free discrete subgroups ...

We compute the front speeds of the Kolmogorov-Petrovsky-Piskunov (KPP) reactive fronts in two prototypes of periodic incompressible flows (the cellular flows and the cat’s eye flows). The computation is based on adaptive streamline diffusion methods for the advection-diffusion type principal eigenvalue problem associated with the KPP front speeds. In the large amplitude regime, internal layers ...

Numerical, two-dimensional, time-dependent hydrodynamical models of geometrically thick accretion discs around black holes are presented. Accretion flows with non-effective radiation cooling (ADAFs) can be both convectively stable or unstable depending on the value of the viscosity parameter α. The high viscosity flows (α ≃ 1) are stable and have a strong equatorial inflow and bipolar outflows....