The dynamics of a (super)particle near the horizon of an extreme ReissnerNordström black hole is shown to be governed by an action that reduces to a (super)conformal mechanics model in the limit of large black hole mass. † Onderzoeksdirecteur FWO, Belgium ⋆ On leave from DAMTP, Univ. of Cambridge, UK

For porcine myocardium, ultrasonic regional deformation parameters, systolic strain (epsilon(sys)) and peak systolic strain rate (SR(sys)), were compared with stroke volume (SV) and contractility [contractility index (CI)] measured as the ratio of end-systolic strain to end-systolic wall stress. Heart rate (HR) and contractility were varied by atrial pacing (AP = 120-180 beats/min, n = 7), incremental dobutamine infusion (DI = 2.5-20 microg. kg(-1). min(-1), n = 7), or continuous esmolol infusion (0.5 mg. kg(-1). min(-1)) + subsequent pacing (120-180 beats/min) (EI group, n = 6). Baseline SR(sys) and epsilon(sys) averaged 5.0 +/- 0.4 s(-1) and 60 +/- 4%. SR(sys) and CI increased linearly with DI (20 microg. kg(-1). min(-1); SR(sys) = 9.9 +/- 0.7 s(-1), P < 0.0001) and decreased with EI (SR(sys) = 3.4 +/- 0.1 s(-1), P < 0.01). During pacing, SR(sys) and CI remained unchanged in the AP and EI groups. During DI, epsilon(sys) and SV initially increased (5 microg. kg(-1). min(-1); epsilon(sys) = 77 +/- 6%, P < 0.01) and then progressively returned to baseline. During EI, SV and epsilon(sys) decreased (epsilon(sys) = 38 +/- 2%, P < 0.001). Pacing also decreased SV and epsilon(sys) in the AP (180 beats/min; epsilon(sys) = 36 +/- 2%, P < 0.001) and EI groups (180 beats/min; epsilon(sys) = 25 +/- 3%, P < 0.001). Thus, for normal myocardium, SR(sys) reflects regional contractile function (being relatively independent of HR), whereas epsilon(sys) reflects changes in SV.

Atrial fibrillation is associated with the fibrosis of subepicardial fatty infiltrates, a process in which cytotoxic lymphocytes might be involved. This remodelling of the atrial subepicardium could contribute to structural remodelling forming a substrate for AF.

The bosonic actions for M2, D3 and M5 branes in their own ddimensional near-horizon background are given in a manifestly SO(p + 1, 2) × SO(d − p − 1) invariant form (p = 2, 3, 5). These symmetries result from a breakdown of ISO(d, 2) (with d = 10 for D3 and d = 11 for M2 and M5) symmetry by the Wess-Zumino term and constraints. The new brane actions, reduce after gaugefixing and solving constraints to (p + 1) dimensional interacting field theories with a non-linearly realized SO(p + 1, 2) conformal invariance. We also present an interacting two-dimensional conformal field theory on a D-string in the near-horizon geometry of a D1+D5 configuration. † Onderzoeksdirecteur FWO, Belgium ⋆ On leave from DAMTP, Univ. of Cambridge, UK

We present a gauge-fixed M 5-brane action: a 6-dimensional field theory of a self-interacting (0,2) tensor multiplet with 32 worldvolume supersymmetries. The quadratic part of this action is shown to be invariant under rigid OSp(8 * |4) superconformal symmetry, with 16 supersymmetries and 16 special supersymmetries.We explore a deep relation between the superconformal symmetry on the worldvolume of the brane and symmetry of the near horizon anti-de Sitter infinite throat geometry of the M 5-brane in space-time. † Onderzoeksdirecteur FWO, Belgium