Secreted enzymatic activities of ectomycorrhizal fungi as a case study of functional diversity and functional redundancy

• Introduction : Many studies deal with taxonomic diversity (TD) or estimation of functional traits of ectomycorrhizal communities. However, to our knowledge, none of them has ever tried to calculate the functional diversity (FD) of those communities, which is of critical importance for the diversity and reliability of nutrient supply to the tree. • Objectives : Here, we propose to evaluate the functional diversity of ECM communities in their potential ability to mobilise nutrients from organic matter, in two different forest stands. • Results : Results show that in both forest stands: TD is strongly correlated with FD.ECM species are functionally redundant within the communities for their abilities to secrete organic matter degrading enzymes.The functional traits (enzymatic activities) of the studied ectomycorrhizal communities are not related within genera, nor within families or phylogenetically related groups of taxa.Some species show a wide phenotypic plasticity for their enzymatic profiles. • Conclusion : This study provides the first evidence of functional redundancy in ectomycorrhizal communities. More studies are now needed to evaluate the robustness of these results at wider ecosystem scales and using other relevant functional trait

A generic software design for Delaunay refinement meshing

This paper describes a generic software designed to implement meshing algorithms based on the Delaunay refinement paradigm. Such a meshing algorithm is generally described through a set of rules guiding the refinement of mesh elements. The central item of the software design is a generic class, called a mesher level, able to handle one of the rules guiding the refinement process. Several instantiations of the mesher level class can be stacked and tied together to implement the whole refinement process. As shown in this paper, the design is flexible enough to implement all currently known mesh generation algorithms based on Delaunay refinement. In particular it can be used to generate meshes approximating smooth or piecewise smooth surfaces, as well as to mesh three dimensional domains bounded by such surfaces. It also adapts to algorithms handling small input angles and various refinement criteria. This design highly simplifies the task of implementing Delaunay refinement meshing algorithms. It has been used to implemented several meshing algorithms in the CGAL library

Courbes d'apprentissage des internes pour la pratique de l'anesthésie loco-régionale sous échographie : étude CAPPRI

L'utilisation de l'échographie s'est imposée en anesthésie loco-régionale (ALR). Son apprentissage par les internes s'effectue le plus souvent au lit du patient mais n'a pas été évalué dans ce contexte. L'objectif de ce travail était de réaliser les courbes d'apprentissage des internes pour la réalisation échoguidée des principaux blocs nerveux périphériques. Dans une étude prospective observationnelle, 8 internes d anesthésie inexpérimentés en ALR échoguidée ont été inclus pendant leur stage de 3 mois en chirurgie orthopédique. Tous les blocs interscaléniques, axillaires, fémoraux et sciatiques étaient inclus et réalisés sous échographie. Pour chaque type de bloc, une courbe évaluant l efficacité des blocs et une courbe évaluant le temps de réalisation (temps inférieur au 75ème percentile de celui de 2 experts) étaient réalisées. Ces temps étaient aussi comparés à ceux des experts et les erreurs ont été analysées. 522 blocs ont été inclus. 91% étaient efficaces, dont plus de 80 % dès les 5 premiers blocs réalisés. Sur le critère de temps, le taux de succès était supérieur à 80% après 25 blocs interscaléniques et fémoraux et après 20 blocs sciatiques. Le temps de réalisation des blocs n était plus différent entre les internes et les experts après 15 blocs de chaque type. La mauvaise visualisation du bout d aiguille était l erreur la plus fréquente (26%) et persistait jusqu à la fin du stage avec une association significative avec les échecs (p<0.0001). L apprentissage de l ALR échoguidée est rapide mais nécessite probablement entre 20 et 25 blocs de chaque type pour atteindre une performance comparable à celle des experts.Learning of ultrasound (US) guided regional anesthesia differs from learning of regional anesthesia using nerve stimulation. The aim of our study was to determine for the main peripheral nerve blocks, the attempts number required by inexperienced anesthesiology residents at bedside to acquire competency in regional anesthesia using US. In a prospective observational study, 8 inexperienced residents were included. All interscalene, axillary, femoral and sciatic blocks were included and performed using US guidance. 2 types of learning curves were constructed for each type of block : learning curves assessing block efficiency and learning curves assessing execution times (rates of efficient blocks with an execution time less than the 75th percentil of that of 2 experts). Execution times were also compared with that of experts and errors distribution during learning was studied. 522 blocks were included. 91% of blocks were efficient and more than 80% at the beginning of the learning. On the criterion of execution time, success rates were greater than 80% after 25 blocks for interscalene and femoral blocks and after 20 blocks for sciatic block. There was no significant difference between experts and residents execution times after the 15th attempt of each block type. Poor visualization of the needle tip was the most frequent error (26% of blocks) and persisted until the end of the course with a significant association with failed blocks (p < 0.0001). Learning of regional anesthesia using US is fast, but requires a number between 20 and 25 blocks of each type to acquire comparable performance to those of experts in terms of block efficiency and execution time.ANGERS-BU Médecine-Pharmacie (490072105) / SudocSudocFranceF

Meshing 3D domains bounded by piecewise smooth surfaces

35 pagesThis paper proposes an algorithm to mesh 3D domains bounded by piecewise smooth surfaces. The algorithm handle multivolume domains defined by surfaces that may be non connected or non manifold. The boundary and subdivision surfaces are assumed to be described by a complex formed by surface patches stitched together along curve segments. The meshing algorithm is a Delaunay refinement and it uses the notion of restricted Delaunay triangulation to approximate the input curve segments and surface patches. The algorithm yields a mesh with good quality tetrahedra and offers a user control on the size of the tetrahedra. The vertices in the final mesh have a restricted Delaunay triangulation to any input feature which is a homeomorphic and accurate approximation of this feature. The algorithm also provides guarantee on the size and shape of the facets approximating the input surface patches. In its current state the algorithm suffers from a severe angular restriction on input constraints. It basically assumes that two linear subspaces that are tangent to non incident and non disjoint input features on a common point form an angle measuring at least 90 degrees

A generic software design for Delaunay refinement meshing

This paper describes a generic software designed to implement meshing algorithms based on the Delaunay refinement paradigm. Such a meshing algorithm is generally described through a set of rules guiding the refinement of mesh elements. The central item of the software design is a generic class, called a mesher level, able to handle one of the rules guiding the refinement process. Several instantiations of the mesher level class can be stacked and tied together to implement the whole refinement process. As shown in this paper, the design is flexible enough to implement all currently known mesh generation algorithms based on Delaunay refinement. In particular it can be used to generate meshes approximating smooth or piecewise smooth surfaces, as well as to mesh three dimensional domains bounded by such surfaces. It also adapts to algorithms handling small input angles and various refinement criteria. This design highly simplifies the task of implementing Delaunay refinement meshing algorithms. It has been used to implemented several meshing algorithms in the CGAL library

Impact de la carence martiale sur la fatigue en anesthésie-réanimation, de l’étude animale à la clinique humaine

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Iron deficiency without anemia is responsible for decreased left ventricular function and reduced mitochondrial complex I activity in a mouse model

BACKGROUND: Iron deficiency (ID), with or without anemia, is frequent in heart failure patients, and iron supplementation improves patient condition. However, the link between ID (independently of anemia) and cardiac function is poorly understood, but could be explained by an impaired mitochondrial metabolism. Our aim was to explore this hypothesis in a mouse model. METHODS AND RESULTS: We developed a mouse model of ID without anemia, using a blood withdrawal followed by 3-weeks low iron diet. ID was confirmed by low spleen, liver and heart iron contents and the repression of HAMP gene coding for hepcidin. ID was corrected by a single ferric carboxymaltose (FCM) injection (ID + FCM mice). Hemoglobin levels were similar in ID, ID + FCM and control mice. ID mice had impaired physical performances and left ventricular function (echocardiography). Mitochondrial complex I activity of cardiomyocytes was significantly decreased in ID mice, but not complexes II, III and IV activities. ID + FCM mice had improved physical performance, cardiac function and complex I activity compared to ID mice. Using BN-PAGE, we did not observe complex I disassembly, but a reduced quantity of the whole enzyme complex I in ID mice, that was restored in ID + FCM mice. CONCLUSIONS: ID, independently of anemia, is responsible for a decreased left ventricular function, through a reduction in mitochondrial complex I activity, probably secondary to a decrease in complex I quantity. These abnormalities are reversed after iron treatment, and may explain, at least in part, the benefit of iron supplementation in heart failure patients with ID

Meshing Volumes with Curved Boundaries

International audienceThis paper introduces a three-dimensional mesh generation al- gorithm for domains whose boundaries are curved surfaces, possibly with sharp features. The algorithm combines a Delaunay-based surface mesher with a Ruppert-like volume mesher, resulting in a greedy scheme to sample the interior and the boundary of the domain simultaneously. The algorithm constructs provably-good meshes, it gives control on the size of the mesh elements through a user-defined sizing field, and it guarantees the accuracy of the approximation of the domain boundary. A notable feature is that the domain boundary has to be known only through an oracle that can tell whether a given point lies inside the object and whether a given line seg- ment intersects the boundary. This makes the algorithm generic enough to be applied to domains with a wide variety of boundary types, such as im- plicit surfaces, polyhedra, level-sets in 3D gray-scaled images, or point-set surfaces