Sensing coral reef connectivity pathways from space

Coral reefs rely on inter-habitat connectivity to maintain gene flow, biodiversity and ecosystem resilience. Coral reef communities of the Red Sea exhibit remarkable genetic homogeneity across most of the Arabian Peninsula coastline, with a genetic break towards the southern part of the basin. While previous studies have attributed these patterns to environmental heterogeneity, we hypothesize that they may also emerge as a result of dynamic circulation flow; yet, such linkages remain undemonstrated. Here, we integrate satellite-derived biophysical observations, particle dispersion model simulations, genetic population data and ship-borne in situ profiles to assess reef connectivity in the Red Sea. We simulated long-term (>20 yrs.) connectivity patterns driven by remotely-sensed sea surface height and evaluated results against estimates of genetic distance among populations of anemonefish, Amphiprion bicinctus, along the eastern Red Sea coastline. Predicted connectivity was remarkably consistent with genetic population data, demonstrating that circulation features (eddies, surface currents) formulate physical pathways for gene flow. The southern basin has lower physical connectivity than elsewhere, agreeing with known genetic structure of coral reef organisms. The central Red Sea provides key source regions, meriting conservation priority. Our analysis demonstrates a cost-effective tool to estimate biophysical connectivity remotely, supporting coastal management in data-limited regions

Transfert du Tendon du Muscle Jambier Postérieur : à propos de 24 patients avec un recul moyen de 42 mois

De janvier 1981 à mars 2007, 24 patients souffrants de paralysie irréversible du SPE, ont bénéficié d’une chirurgie de transfert du tendon du muscle jambier postérieur. Les résultats fonctionnels de cette étude rétrospective ont été quantifiiés par la méthode d’évaluation fonctionnelle de STANMORE. Il s’agissait de 14 hommes et 8 femmes, avec un âge moyen de 41,5 ans (18 ans - 65 ans), le délai moyen de prise en charge était de 11 ans (18 mois - 20 ans). Le tendon du muscle jambier postérieur a été fixé : 14 fois sur le 3ème cunéiforme, 6 fois sur le cuboïde, 4 fois sur le 2ème cunéiforme. La fixation du tendon transféré a été assurée par un bouton métallique 17 fois, une vis d’interférence 3 fois, des points trans osseux 3 fois, une agrafe de BLOUNT une fois. Conclusion : le transfert du tendon du muscle jambier postérieur sur le dos du pied est une méthode qui permet de faire retrouver au pied les mouvements perdus suite à la paralysie irréversible du SPE. Ce transfert restaurera la fonction des muscles paralysé

Acute haemodynamic effects of IL-6 treatment in vivo: Involvement of vagus nerve in NO-mediated negative inotropism

Interleukin-6 (IL-6) reduces myocardial haemodynamics. However, the intrinsic mechanisms of IL-6 effects are not known. We hypothesized that nitric oxide (NO) synthesised by neuronal synthase (nNOS) can be the molecular mediator of IL-6-mediated cardiac effects. Thus, we investigated in vivo after IL-6 acute administration: (1) the role of NO pathway; (2) the importance of NO derived from nNOS located in intracardiac vagal ganglion in the anterior surface of the left ventricle. SpragueeDawley (SD) rats (225e250 g) were anaesthetized (sodium pentobarbital 30 mg/kg intraperitoneally administered) and ventilated. The effects of a single IL-6 bolus (100 mg/kg intravenously administered) were studied in four experimental groups: (a) IL-6 (nZ6), (b) IL-6 plus 30 mg/kg of L-NAME (an eNOS and nNOS inhibitor; nZ6), (c) IL-6 plus 25 mg/kg of 7-NI (a specific nNOS inhibitor; nZ6), (d) IL-6 plus vagal resection (nZ6). We evaluated the following parameters: mean aortic pressure (MAP), left ventricular end systolic pressure (LVESP), left ventricular positive peak dP/dt (PP dP/dt). Data are expressed as meanGsem. IL-6 caused a transient but significant reduction of MAP (21.8% of basal: p!0.05), LVESP (from 130G4.2 to 1056.5 mmHg: p!0.05) and PP dP/dt (from 5390G158 to 4400G223 mmHg/s, p!0.02). Concomitant treatment with L-NAME or 7-NI totally abolished IL-6 effects. Vagal resection significantly reduced the haemodynamic effects (MAP: 10% of basal: pZns; LVEDS: from 125G7.3 to 117G6.8 mmHg, p!0.05; PP dP/dt from 5500G150 to 5000G143 mmHg/s, p!0.05). We conclude that acute administration of IL-6 caused transient but significant cardiac negative inotropism. IL-6 haemodynamic effects are partly due to NO synthesised by nNOS located in vagal left ventricular ganglia. 2005 Elsevier Ltd. All rights reserved

Estimating model error covariances in nonlinear state-space models using Kalman smoothing and the expectation-maximisation algorithm

International audienceSpecification and tuning of errors from dynamical models are important issues in data assimilation. In this work, we propose an iterative expectation-maximization (EM) algorithm to estimate the model-error covariances using classical extended and ensemble versions of the Kalman smoother. We show that, for additive model errors, the estimate of the error covariance converges. We also investigate other forms of model error, such as parametric or multiplicative errors. We show that additive Gaussian model error is able to compensate for non-additive sources of error in the algorithms we propose. We also demonstrate the limitations of the extended version of the algorithm and recommend the use of the more robust and flexible ensemble version. This article is a proof of concept of the methodology with the Lorenz-63 attractor. We developed an open-source Python library to enable future users to apply the algorithm to their own nonlinear dynamical models

Experimental Study on Sediment Supply-Limited Bedforms in a Coastal Context

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