604 research outputs found

    Long-term trends in the longevity of scientific elites: evidence from the British and the Russian academies of science.

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    National science academies represent intellectual elites and vanguard groups in the achievement of longevity. We estimated life expectancy (LE) at age 50 of members of the British Royal Society (RS) for the years 1670-2007 and of members of the Russian Academy of Sciences (RAS) for the years 1750-2006. The longevity of academicians was higher than that of their corresponding national populations, with the gap widening from the 1950s. Since the 1980s, LE in the RS has been higher than the maximum LE among all high-income countries. In each period, LE in the RS was greater than in the RAS, although since the 1950s it has risen in parallel in the two academies. This steep increase shared by academicians in Britain and Russia suggests that general populations have the potential for a substantial increase in survival to high ages

    Conséquences démographiques du sida en Abidjan : 1986-1992

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    Les statistiques de l'état civil et des formations sanitaires sont notoirement peu utilisées en Afrique pour étudier les tendances de la mortalité. L'étude d'Abidjan montre que c'est une situation très regrettable, car ces statistiques peuvent fournir de précieux renseignements sur l'état sanitaire de la population. Dans le cas présent, l'analyse fine des tendances de la mortalité, couplée avec l'analyse des causes de décès dans les hôpitaux, révèle assez précisément les conséquences démographiques du sida dans la capitale de la Côte d'Ivoire, malgré l'imperfection des données. Les estimations indiquent que près de 25 000 personnes seraient décédées du sida entre 1986 et 1992, les sept premières années de l'épidémie, ce qui confirme qu'Abidjan est une des villes les plus touchées au monde par cette troublante épidémie. Ce sont surtout les jeunes de sexe masculin qui ont été les plus touchés, dans toutes les couches de la société. Un modèle a permis de reconstruire la dynamique de l'épidémie, qui montre que le premier pic des infections se serait produit vers 1987. On peut s'attendre à une moyenne d'environ 7 000 cas de sida par an dans la ville jusqu'à l'an 2000, ce qui aura des conséquences importantes sur l'utilisation des infrastructures hospitalières. L'importance numérique de ces estimations souligne l'urgence de renforcer la lutte contre l'épidémie de sida en Côte d'Ivoire et dans le monde. (Résumé d'auteur

    A PEDAGOGICAL APPROACH TO IMPROVING STUDENTS’ USE OF METACOGNITIVE STRATEGIES

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    Ph.D.Ph.D. Thesis. University of Hawaiʻi at Mānoa 201

    Designing and implementing an assay for the detection of rare and divergent NRPS and PKS clones in European, Antarctic and Cuban soils

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    The ever increasing microbial resistome means there is an urgent need for new antibiotics. Metagenomics is an underexploited tool in the field of drug discovery. In this study we aimed to produce a new updated assay for the discovery of biosynthetic gene clusters encoding bioactive secondary metabolites. PCR assays targeting the polyketide synthases (PKS) and non-ribosomal peptide synthetases (NRPS) were developed. A range of European soils were tested for their biosynthetic potential using clone libraries developed from metagenomic DNA. Results revealed a surprising number of NRPS and PKS clones with similarity to rare Actinomycetes. Many of the clones tested were phylogenetically divergent suggesting they were fragments from novel NRPS and PKS gene clusters. Soils did not appear to cluster by location but did represent NRPS and PKS clones of diverse taxonomic origin. Fosmid libraries were constructed from Cuban and Antarctic soil samples; 17 fosmids were positive for NRPS domains suggesting a hit rate of less than 1 in 10 genomes. NRPS hits had low similarities to both rare Actinobacteria and Proteobacteria; they also clustered with known antibiotic producers suggesting they may encode for pathways producing novel bioactive compounds. In conclusion we designed an assay capable of detecting divergent NRPS and PKS gene clusters from the rare biosphere; when tested on soil samples results suggest the majority of NRPS and PKS pathways and hence bioactive metabolites are yet to be discovere

    Parental effects on early life history traits of haddock Melanogrammus aeglefinus

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    Gametes from five male and three female haddock ( Melanogrammus aeglefinus ) were crossed to produce 15 half-sibling families that were used to evaluate potential parental contributions to early life history variability. Larval morphology at 0 and 5 days post-hatch (dph) and time to starvation in the absence of food were examined. Maternal influences on larval standard length and yolk area were significant at 0 and 5 dph. Paternal effects on larval standard length were significant at 0 and 5 dph, whereas paternal effects on yolk area were only significant at 5 dph. Larval eye diameter was influenced by maternity at day 0 post-hatch and by both maternity and paternity at 5 dph. Myotome height of larvae was subject to maternal and paternal influences at 0 and 5 dph. Growth rate was significantly influenced by both paternity and maternity. Yolk utilization efficiency was significantly influenced by parental interaction, while the time taken for larvae to die in the absence of food was affected only by maternity. Results of this study not only confirm the importance of female contributions to larval development but also indicate a paternal influence on the development and the early life history success of marine fish

    Two-dimensional flexible high diffusive spin circuits

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    Owing to their unprecedented electronic properties, graphene and two-dimensional (2D) crystals have brought fresh opportunities for advances in planar spintronic devices. Graphene is an ideal medium for spin transport while also being an exceptionally resilient material for flexible electronics. However, these extraordinary traits have never been combined to create flexible graphene spin circuits. Realizing such circuits could lead to bendable strain-based spin sensors, a unique platform to explore pure spin current based operations and low power flexible nanoelectronics. Here, we demonstrate graphene spin circuits on flexible substrates for the first time. These circuits, realized using chemical vapour deposited (CVD) graphene, exhibit large spin diffusion coefficients ~0.19-0.24 m2s-1 at room temperature. Compared to conventional devices of graphene on Si/SiO2 substrates, such values are 10-20 times larger and result in a maximum spin diffusion length ~10 um in graphene achieved on such industry standard substrates, showing one order enhanced room temperature non-local spin signals. These devices exhibit state of the art spin diffusion, arising out of a distinct substrate topography that facilitates efficient spin transport, leading to a scalable, high-performance platform towards flexible 2D spintronics. Our innovation unlocks a new domain for the exploration of strain-dependent spin phenomena and paves the way for flexible graphene spin memory-logic units and surface mountable sensors.Comment: Figures made compatible with all operating systems and PDF viewer

    The Pharmacological Effect Of Bothrops Neuwiedii Pauloensis (jararaca-pintada) Snake Venom On Avian Neuromuscular Transmission.

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    The neuromuscular effects of Bothrops neuwiedii pauloensis (jararaca-pintada) venom were studied on isolated chick biventer cervicis nerve-muscle preparations. Venom concentrations of 5-50 micro g/ml produced an initial inhibition and a secondary increase of indirectly evoked twitches followed by a progressive concentration-dependent and irreversible neuromuscular blockade. At venom concentrations of 1-20 micro g/ml, the responses to 13.4 mM KCl were inhibited whereas those to 110 micro M acetylcholine alone and cumulative concentrations of 1 micro M to 10 mM were unaffected. At venom concentrations higher than 50 micro g/ml, there was pronounced muscle contracture with inhibition of the responses to acetylcholine, KCl and direct stimulation. At 20-24 degrees C, the venom (50 g/ml) produced only partial neuromuscular blockade (30.7 +/- 8.0%, N = 3) after 120 min and the initial inhibition and the secondary increase of the twitch responses caused by the venom were prolonged and pronounced and the response to KCl was unchanged. These results indicate that B.n. pauloensis venom is neurotoxic, acting primarily at presynaptic sites, and that enzyme activity may be involved in this pharmacological action.36617-2

    Marginal Eyespots on Butterfly Wings Deflect Bird Attacks Under Low Light Intensities with UV Wavelengths

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    Predators preferentially attack vital body parts to avoid prey escape. Consequently, prey adaptations that make predators attack less crucial body parts are expected to evolve. Marginal eyespots on butterfly wings have long been thought to have this deflective, but hitherto undemonstrated function.Here we report that a butterfly, Lopinga achine, with broad-spectrum reflective white scales in its marginal eyespot pupils deceives a generalist avian predator, the blue tit, to attack the marginal eyespots, but only under particular conditions-in our experiments, low light intensities with a prominent UV component. Under high light intensity conditions with a similar UV component, and at low light intensities without UV, blue tits directed attacks towards the butterfly head.In nature, birds typically forage intensively at early dawn, when the light environment shifts to shorter wavelengths, and the contrast between the eyespot pupils and the background increases. Among butterflies, deflecting attacks is likely to be particularly important at dawn when low ambient temperatures make escape by flight impossible, and when insectivorous birds typically initiate another day's search for food. Our finding that the deflective function of eyespots is highly dependent on the ambient light environment helps explain why previous attempts have provided little support for the deflective role of marginal eyespots, and we hypothesize that the mechanism that we have discovered in our experiments in a laboratory setting may function also in nature when birds forage on resting butterflies under low light intensities
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