969 research outputs found
The evolutionary dynamics of laying date in the pied flycatcher Ficedula hypoleuca
Current global warming is unequivocally impacting biodiversity at an unprecedent
rates. Such negative impact can be quantified on species distribution
and diversity, but understanding biodiversity loss can only be fully achieved
by considering the capacity of populations to track prevailing environmental
conditions. Thus, an evolutionary approach is inevitable to comprehend how
populations of species adapt under a scenario of climate change. This PhD follows
a research agenda to quantify the variation of the timing of breeding laying
date and the relative role of environmental variation on phenotypic selection
along the evolutionary mechanisms that may explain local adaptation. Taking
advantage of a long-term monitored population of pied flycatchers Ficedula hypoleuca,
I detected a lack of temporal trend of laying date over 29 years despite
highly variable environmental conditions during the same time period. A lack
of repeatability of the date of breeding, suggesting a high variability among
individuals in laying date and explaining variance of laying date. The intensity of
phenotypic selection on laying date was strongest when environmental conditions
were poor, specifically when minimum temperatures in April were lowest and
May were highest. Despite negative selection on laying date, there was no
evolutionary response at genetic level, suggesting that non-genetic mechanism
may explain local adaptation. Accordingly, we found individual-by-environment
interactions explaining phenological variation that can be partially explained by
genotype-by-environmental interaction. This PhD stresses first, the crucial role
that multiple environmental factors may play on the evolutionary dynamics of
life-history traits and, second, that evolutionary mechanisms that do not involve
genetic changes, namely genotype-by- environmental interactions, may play a
pivotal role on local adaptation
Textural development in sulfide-matrix ore breccias in the Aguablanca Ni-Cu deposit, Spain, revealed by X-ray fluorescence microscopy
The intrusion-hosted Ni-Cu sulfide deposit at Aguablanca in south-western Spain contains a high proportion of ores in the form of sulfide-matrix ore breccias. These are polymict, comprising autoliths and xenoliths in sulfide-rich and/or sulfide-poor matrices. Inclusion lithologies include calc-silicate skarn rocks from the adjacent marbles, ultramafic and mafic cumulates, and remelted and recrystallized mafic rocks containing spinifex-like textures.
Breccia textures have been investigated at mm to cm scale using desk-top and synchrotron-based microbeam XRF mapping which reveal a number of distinctive common features: disaggregation of inclusions into adjacent sulfide along original silicate grain boundaries; complex reverse and oscillatory zoning in Cr content of clinopyroxene grains within sulfide and inside inclusions; narrow reaction rims between country rock clasts and enclosing silicates; and preferential disposition of pyroxene crystals within pyrrhotite-pentlandite aggregates (original MSS) relative to inclusion-poor chalcopyrite.
The observed range of textures is explained by a model of percolation of molten sulfide through a pre-existing silicate-matrix intrusion breccia, preferentially displacing a cotectic or eutectic plagioclase-pyroxene melt. The process is analogous to that believed to have formed interspinifex ore in komatiite-hosted deposits, and also to that responsible for superficially similar sulfide matrix ore breccias at Voisey’s Bay. The preserved range of textures is interpreted as being due to late stage gravity-driven percolation of sulfide liquid from above into a pre-existing partially molten intrusion breccia. This intrusion breccia itself may have been emplaced into the neck of the Aguablanca stock, in the waning stages of magma flow
Decarboxylative Alkynylation and Cyanation of Carboxylic Acids using Photoredox Catalysis and Hypervalent Iodine Reagents
Alkynes and nitriles are important functional groups that serve as versatile building blocks in organic synthesis and find applications in material and medicinal sciences. A convenient and straightforward access to both classes of compounds under mild conditions is, therefore, highly desirable. Herein, we disclose the decarboxylative alkynylation and cyanation of broadly available carboxylic acids using photoredox catalysis and hypervalent iodine reagents. Choices of both catalysts and reagents were crucial. Computational and experimental studies revealed two different possible mechanisms that are dictated by the oxidation potential of the reagents: radical for alkynylation, ionic for cyanation
Campagne HALICAL 2 de pêche à la palangre de fond dans le Nord et sur la ride des Loyauté en Nouvelle-Calédonie : N.O. Alis, 17-27 janvier et 1-17 février1995
La campagne HALICAL 2 du N.O. "Alis" de l'ORSTOM s'est déroulée 17 au 27 janvier et du 1er au 17 février 1995 dans le nord et sur la Ride des Loyauté dans le cadre du programme ZoNéCo. Son objectif était de réaliser une estimation des potentialités halieutiques par pêches à la palangre de fond entre 300 et 800 m dans les zones qui furent cartographiées par l'EM 12 du N.O. "l'Atalante" durant la campagne ZoNéCo 2. 34 poses furent effectuées dont 16 dans le Nord et 18 sur la Ride des Loyauté. Une palangre d'environ 1000 hameçons fut mise à l'eau chaque jour, ce qui a représenté un effort de pêche total de 33600 hameçons. Les prises furent identifiées, dénombrées et pesées au niveau spécifique. 46 espèces différentes furent capturées pour un poids total de 4977 kg dont 3077 kg (62%) d'espèces d'intérêt commercial car dépourvues d'ichtyosarcotoxisme. (D'après résumé d'auteur
Spatial distribution in Norwegian lemming Lemmus lemmus in relation to the phase of the cycle
Competition between individuals of the same or different species affects spatial distribution of organisms at any given time. Consequently, a species geographical distribution is related to population dynamics through density-dependent processes. Small Arctic rodents are important prey species in many Arctic ecosystems. They commonly show large cyclic fluctuations in abundance offering a potential to investigate how landscape characteristics relates to density-dependent habitat selection. Based on long-term summer trapping data of the Norwegian lemming (Lemmus lemmus) in the Scandinavian Mountain tundra, we applied species distribution modeling to test if the effect of environmental variables on lemming distribution changed in relation to the lemming cycle. Lemmings were less habitat specific during the peak phase, as their distribution was only related to primary productivity. During the increase phase, however, lemming distribution was, in addition, associated with landscape characteristics such as hilly terrain and slopes that are less likely to get flooded. Lemming habitat use varied during the cycle, suggesting density-dependent changes in habitat selection that could be explained by intraspecific competition. We believe that the distribution patterns observed during the increase phase show a stronger ecological signal for habitat preference and that the less specific habitat use during the peak phase is a result of lemmings grazing themselves out of the best habitat as the population grows. Future research on lemming winter distribution would make it possible to investigate the year around strategies of habitat selection in lemmings and a better understanding of a fundamental actor in many Arctic ecosystems.publishedVersio
Room-Temperature Decarboxylative Alkynylation of Carboxylic Acids Using Photoredox Catalysis and EBX Reagents
Alkynes are used as building blocks in synthetic and medicinal chemistry, chemical biology, and materials science. Therefore, efficient methods for their synthesis are the subject of intensive research. Herein, we report the direct synthesis of alkynes from readily available carboxylic acids at room temperature under visible-light irradiation. The combination of an iridium photocatalyst with ethynylbenziodoxolone (EBX) reagents allowed the decarboxylative alkynylation of carboxylic acids in good yields under mild conditions. The method could be applied to silyl-, aryl-, and alkyl- substituted alkynes. It was particularly successful in the case of alpha-amino and alpha-oxo acids derived from biomass
New observations by X-ray fluorescence microscopy provide insights for the origin of Aguablanca sulfide-matrix breccias in SW Spain
Depto. de Mineralogía y PetrologíaFac. de Ciencias GeológicasTRUEMinisterio de Economía y Competitividadpu
Room temperature decarboxylative cyanation of carboxylic acids using photoredox catalysis and cyanobenziodoxolones: a divergent mechanism compared to alkynylation
The one-step conversion of aliphatic carboxylic acids to the corresponding nitriles has been accomplished via the merger of visible light mediated photoredox and cyanobenziodoxolones (CBX) reagents. The reaction proceeded in high yields with natural and non-natural alpha-amino and alpha-oxy acids, affording a broad scope of nitriles with excellent tolerance of the substituents in the alpha position. The direct cyanation of dipeptides and drug precursors was also achieved. The mechanism of the decarboxylative cyanation was investigated both computationally and experimentally and compared with the previously developed alkynylation reaction. Alkynylation was found to favor direct radical addition, whereas further oxidation by CBX to a carbocation and cyanide addition appeared more favorable for cyanation. A concerted mechanism is proposed for the reaction of radicals with EBX reagents, in contrast to the usually assumed addition elimination process
Diagnóstico situacional Hospital Gaspar García Laviana- Rivas y Ernesto Sequeira- Región Autónoma Atlántico Sur. Nicaragua. Año 2004.
Estudio de tipo descriptivo de corte transversal, en los Hospitales Ernesto Sequeira de la Región Autónoma del Atlántico Sur y Gaspar García Laviana de Rivas durante el año 2004. Se encontró que en ambos Hospitales brindan atención general, de prioridad Materno-Infantil, ubicados en las cabeceras de los departamentos; pertenecen al Segundo nivel de atención, con un nivel de complejidad básico, de referencias departamental para los centros de salud, cuyo propietario es el Ministerio de Salud. Con poblaciones objetivos mayores de 175,000 habitantes donde el 65% de las personas son niños o mujeres en edad de procrear. La cartera de servicios que ofertan ambos hospitales es acorde a su complejidad en las que se encuentran las cuatro especialidades básicas Medicina Interna, Cirugía General, Pediatría y Gineco obstetricia y los servicios de apoyo tales como: Farmacia, Radiología, Laboratorio así como en su estructura física cuenta con consultorios para consulta externa, emergencia, quirófanos, salas de parto y camas censables. El número de recursos humanos en cada hospital es mayor a 300 personas, donde el 55 al 60% es asistencial. En los recursos financieros el 80% del presupuesto proviene de fondo fiscal y el mayor gasto es en el pago de recursos humanos. El equipamiento asistencial de los hospitales se encuentra desfasado y obsoleto, entre el 20 al 40% en regular y muy mal estado y tienen más de un año de estar sin funcionamiento y no han sido reparados. El modelo de gestión de ambos hospitales es tradicional, sin implementación de herramientas gerenciales, ni toma de decisiones. La producción de servicios es baja en relación a su capacidad instalada
Influenza vaccination coverage against seasonal and pandemic influenza and their determinants in France: a cross-sectional survey
BACKGROUND: Following the emergence of the influenza A(H1N1)2009 virus, the French ministry of health decided to offer free vaccination against pandemic influenza to the entire French population. Groups of people were defined and prioritised for vaccination. METHODS: We took a random sample of the population of mainland France and conducted a retrospective cross-sectional telephone survey to estimate vaccination coverage against seasonal and pandemic influenza and to identify determinants of these vaccinations. RESULTS: 10,091 people were included in the survey. Overall seasonal influenza vaccination coverage (IVC) remained stable in the population from the 2008-2009 season to the 2009-2010 season reaching 20.6% and 20.8% respectively. Overall pandemic IVC in the French population is estimated to be 11.1% (CI95%: 9.8 - 12.4). The highest pandemic IVC was observed in the 0-4 years age group. For individuals with health conditions associated with higher risk of influenza, pandemic IVC was estimated to be 12.2% (CI95%: 9.8 - 15.1). The main determinants associated with pandemic influenza vaccine uptake were: living in a household with a child < 5 years OR(adj): 2.0 (CI95%: 1.3 - 3.1) or with two children < 5 years or more, OR(adj): 2.7 (CI95%: 1.4 - 5.1), living in a household where the head of the family is university graduate (>2 years), OR(adj): 2.5 (CI95%: 1.5 - 4.1), or has a higher professional and managerial occupation, OR(adj): 3.0 (CI95%: 1.5 - 5.5) and being vaccinated against seasonal influenza, OR(adj): 7.1 (CI95%: 5.1 - 10.0). Being an individual with higher risk for influenza was not a determinant for pandemic influenza vaccine uptake. These determinants are not the same as those for seasonal influenza vaccination. CONCLUSIONS: Overall A(H1N1)2009 influenza vaccine uptake remained low, particularly among individuals with higher risk for influenza and was lower than that observed for seasonal influenza. The reasons behind people's reluctance to be vaccinated need to be investigated further
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