Puentes, 1802: la rupture du plus grand barrage du monde, ou le double echec d’Antonio de Robles. Le rapport Betancourt

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Barrages et essais en vraie grandeur : auscultation et surveillance

La conception et la réalisation des barrages relèvent de la méthode expérimentale compte tenu de la difficulté à modéliser le corps de l’ouvrage et sa fondation. Le site et la structure qui y est implantée, constituent un laboratoire. La surveillance du comportement pour contrôler la sécurité et améliorer l’économie, s’appuie sur l’observation et l’auscultation par la mesure. On retrace dans cet article, l’histoire de la constitution des outils nécessaires à l’obtention d’une mesure cohérente. Les différents acteurs sont considérés ainsi que la dimension internationale des échanges et transferts technologiques.Design and construction of dams are based upon experimental method due to difficulty of assessing actual conditions of structure and its foundation. Site and works may be considered by themselves as a laboratory. For safety control and economical improvement, surveillance of dam and foundation behavior rely on observation and monitoring. History of development of instrumentation for a performing measurement is given in broad lines. Various implied actors are considered as well as the international framework and technological exchanges

Barrages et essais en vraie grandeur : auscultation et surveillance

La conception et la réalisation des barrages relèvent de la méthode expérimentale compte tenu de la difficulté à modéliser le corps de l’ouvrage et sa fondation. Le site et la structure qui y est implantée, constituent un laboratoire. La surveillance du comportement pour contrôler la sécurité et améliorer l’économie, s’appuie sur l’observation et l’auscultation par la mesure. On retrace dans cet article, l’histoire de la constitution des outils nécessaires à l’obtention d’une mesure cohérente. Les différents acteurs sont considérés ainsi que la dimension internationale des échanges et transferts technologiques.Design and construction of dams are based upon experimental method due to difficulty of assessing actual conditions of structure and its foundation. Site and works may be considered by themselves as a laboratory. For safety control and economical improvement, surveillance of dam and foundation behavior rely on observation and monitoring. History of development of instrumentation for a performing measurement is given in broad lines. Various implied actors are considered as well as the international framework and technological exchanges

André Coyne, de la Dordogne au Zambèze, la passion de construire

Introduction Une poignée d’ingénieurs formés dans une vallée du Massif Central, sous la direction d’un des plus grands ingénieurs de génie civil du xxe siècle, ont pu au sortir de la deuxième guerre mondiale, en moins de 15 ans s‘imposer sur la scène internationale au point d’y concevoir deux des plus grands barrages au monde avant de continuer leur épopée sur les cinq continents. Qui était cet homme qui anima cette petite phalange, dont la postérité plus de cinquante ans après sa mort, est e..

À propos de la ruina montium de Pline l’Ancien : une lecture technique du site de Las Médulas (Léon, Espagne)

Bien que résultant d’une profonde blessure infligée par l’homme à la Nature, le paysage de Las Médulas (León, Espagne) a été inscrit au patrimoine mondial de l’humanité en tant que conservatoire exceptionnel des techniques préindustrielles d’exploitation minière et champ d’étude privilégié de leur impact sur l’environnement quelque vingt siècles plus tard (fig. 2). Ce site est l’un des plus fameux qu’aient laissés les Romains de l’exploitation de l’or alluvial d’Espagne. Plusieurs décennies d..

Cytomegalovirus reactivation enhances the virulence of Staphylococcus aureus pneumonia in a mouse model

International audienceObjectives: Cytomegalovirus (CMV) reactivation in intensive care unit patients may increase mortality and favour bacterial pneumonia. We developed a murine model to compare the severity of staphylococcal pneumonia after CMV reactivation and in CMV-negative mice. Methods: Balb/c mice were primo-infected with murine cytomegalovirus (MCMV n = 90) or received saline (control n = 90). After latency, all mice underwent caecal ligation and puncture to trigger MCMV reactivation in MCMV primary-infected mice. Surviving animals received an intra-nasal inoculation with methicillin-susceptible Staphylococcus aureus (MSSA) to induce pneumonia. Mortality, lung bacterial count, histology and interferon-alpha and gamma serum levels were compared in MCMV reactivated and control mice 2, 5 and 15 days after pneumonia. Results: AfterMSSA pneumonia, MCMV mice showed a trend towards a higher mortality (9.4% versus 0%; p 0.09) and a higher weight loss (2.2 (0.6-4.1 g) versus 0.7 (-0.3 to 1.3 g); p 0.005). The lung bacterial countwas higher in MCMV mice 2 days (5 x 10(3) (10(3) to 3 x 10(5)) versus 10(2) (0 to 4 x 10(2)) CFU/lung; p 0.007) and 5 days (2.5 x 10(4) (1.6 x 10(4) to 6.5 x 10(5)) versus 15 (10-40) CFU/lung; p 0.005) after MSSA pneumonia. 8/40 (20%) MCMV mice developed lung abscesses compared to 0% in control (p 0.011). Interferon-alpha serum levels 2 days after staphylococcal pneumonia were higher in MCMV mice. Conclusions: MCMV reactivation decreased lung bacterial clearance and favoured the development of staphylococcal abscessing pneumonia. CMV reactivation may be responsible for a higher susceptibility to bacterial sepsis. (C) 2016 European Society of Clinical Microbiology and Infectious Diseases. Published by Elsevier Ltd. All rights reserved

Improving the yellow pigment content of bread wheat flour by selecting the three homoeologous copies of Psy1

The yellow pigment content (YPC) of endosperm affects the quality and nutritional value of wheat grain products. Major quantitative trait loci (QTL) for endosperm YPC have been repeatedly mapped on chromosomes 7A and 7B in durum and bread wheats. The genes coding for phytoene synthase (PSY1), which is involved in the biosynthesis of carotenoids, generally co-segregate with these QTL, indicating their role in determining YPC. Here, to study the genetic factors underlying endosperm YPC in bread wheat, the sequence polymorphism of the homoeologous A, B and D copies of genes coding for PSY1, Psy-A1, Psy-B1, and Psy-D1, was studied in a worldwide core collection, which was also phenotyped for flour YPC. Seven novel alleles of Psy-A1 and two novel alleles of Psy-B1 were detected, which confirms the high level of polymorphism of these genes. Two major QTL with respective candidate genes Psy-A1 and Psy-B1 were identified in the distal region of chromosomes 7A and 7B using progeny of a cross between Apache and Ornicar, high and low YPC cultivars, respectively. Association mapping confirms the role of these genes in YPC and shows that the D copy also significantly influences this trait. These results indicate that breeders need to consider all three Psy1 copies when seeking to improve the YPC of wheat endosperm

The cost of host genetic resistance on body condition: evidence from divergently selected sheep

International audienceTrade-offs between host resistance to parasites and host growth or reproduction can occur due to allocation of limited available resources between competing demands. To predict potential trade-offs arising from genetic selection for host resistance, a better understanding of the associated nutritional costs is required. Here, we studied resistance costs by using sheep from lines divergently selected on their resistance to a common blood-feeding gastro-intestinal parasite (Haemonchus contortus). First, we assessed the effects of selection for high or low host resistance on condition traits (body weight, back fat, and muscle thickness) and infection traits (parasite fecal egg excretion and loss in blood haematocrit) at various life stages, in particular during the periparturient period when resource allocation to immunity may limit host resistance. Second, we analysed the condition-infection relationship to detect a possible trade-off, in particular during the periparturient period. We experimentally infected young females in four stages over their first 2 years of life, including twice around parturition (at 1 year and at 2 years of age). Linear mixed-model analyses revealed a large and consistent between-line difference in infection traits during growth and outside of the periparturient period, whereas this difference was strongly attenuated during the periparturient period. Despite their different responses to infection, lines had similar body condition traits. Using covariance decomposition, we then found that the phenotypic relationship between infection and condition was dominated by direct infection costs arising from parasite development within the host. Accounting for these within-individual effects, a cost of resistance on body weight was detected among ewes during their first reproduction. Although this cost and the reproductive constraint on resistance are unlikely to represent a major concern for animal breeding in nutrient-rich environments, this study provides important new insights regarding the nutritional costs of parasite resistance at different lifestages and how these may affect response to selection