We consider probability measure preserving discrete groupoids, group actions and equivalence relations in the context of general spaces. study for these objects notions cost, $\beta$-invariant some higher-dimensional variants. also propose various convergence results about $\ell^2$-Betti numbers rank gradient sequences actions, groupoids or under weak finiteness assumptions. In particular we co...

A bstract Using the upper bound on inelastic reaction cross-section implied by S-matrix unitarity, we derive thermally averaged maximum dark matter (DM) annihilation rate for general k → 2 number-changing reactions, with ≥ 2, taking place either entirely within sector, or involving standard model fields. This translates to a mass of particle saturating observed DM abundance, which, dominantly s...

Temperature-induced limitations on the capacity of the cardiorespiratory system to transport oxygen from the environment to the tissues, manifested as a reduced aerobic scope (maximum minus standard metabolic rate), have been proposed as the principal determinant of the upper thermal limits of fishes and other water-breathing ectotherms. Consequently, the upper thermal niche boundaries of these...