Abstract. We are interested in the simulation of P-SV seismic wave propagation by a high-order Discontinuous Galerkin method based on centered fluxes at the interfaces combined with a leap-frog time-integration. This non-diffusive method, previously developed for the Maxwell equations [4,9,20], is particularly well adapted to complex topographies and fault discontinuities in the medium. We prove that the scheme is stable under a CFL type condition and that a discrete energy is preserved on an infinite domain. Convergence properties and efficiency of the method are studied through numerical simulations in two and three dimensions of space.Résumé. Nous nous intéressonsà la propagation d'ondes sismiques de types P et SV par une méthode de Galerkin Discontinue d'ordreélevé basée sur des flux centrés aux interfaces combinésà un schéma saute-mouton en temps. Cette méthode non-dissipative, précédemment développée pour leséquations de Maxwell [4,9,20], est particulièrement bien adaptéeà des milieux présentant une topographie complexe ou contenant des failles. On prouve la stabilité du schéma sous une condition de type CFL ainsi que la conservation d'une energie discrète dans un domaine infini. L'efficacité de la méthode est illustrée par des simulations numériques en deux et trois dimensions d'espace.

Abstract. We define discrete differential operators such as grad, div and curl, on general two-dimensional non-orthogonal meshes. These discrete operators verify discrete analogues of usual continuous theorems: discrete Green formulae, discrete Hodge decomposition of vector fields, vector curls have a vanishing divergence and gradients have a vanishing curl. We apply these ideas to discretize div-curl systems. We give error estimates based on the reformulation of these systems into equivalent equations for the potentials. Numerical results illustrate the use of the method on several types of meshes, among which degenerating triangular meshes and non-conforming locally refined meshes.

Aim: Astroglial connexins (Cxs) 30 and 43 are engaged in gap junction and hemichannel activities. Evidence suggests that these functional entities contribute to regulating neurotransmission, thereby influencing brain functions. In particular, preclinical and clinical findings highlight a role of Cx43 in animal models of depression.However, the role of these proteins in response to currently available psychotropic drugs is still unknown. Methods: To investigate this, we evaluated the behavioural effects of the genetic and pharmacological inactivation of Cx43 on the antidepressant-and anxiolytic-like activities of the selective serotonin reuptake inhibitor fluoxetine and the benzodiazepine diazepam, respectively. Results: A single administration of fluoxetine (18 mg/kg; i.p.) produced a higher increase in hippocampal extracellular serotonin levels, and a greater antidepressantlike effect in the tail suspension test in Cx43 knock-down (KD) mice bred on a C57BL/6 background compared to their wild-type littermates. Similarly, in outbred Swiss wild-type mice, the intra-hippocampal injection of a shRNA-Cx43 or the acute systemic injection of the Cxs inhibitor carbenoxolone (CBX: 10 mg/kg; i.p.) potentiated the antidepressant-like effects of fluoxetine. Evaluating the effects of such strategies on diazepam (0.5 mg/kg; i.p.), the results indicate that Cx43 KD mice or wild-types injected with a shRNA-Cx43 in the amygdala, but not in the hippocampus, attenuated the anxiolytic-like effects of this benzodiazepine in the elevated plus maze. The chronic systemic administration of CBX mimicked the latter observations. Conclusion: Collectively, these data pave the way to the development of potentiating strategies in the field of psychiatry based on the modulation of astroglial Cx43. K E Y W O R D Santidepressant, anxiolytic, astrocytes, Connexin 43, hippocampus, serotonin 2 of 17 | PORTAL eT AL.