963 resultados para curva ellittica cubica liscia Nagell-Lutz Mordell legge di gruppo punti razionali


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The flavivirus NS5 protein is one of the most important proteins of the replication complex, and cellular proteins can interact with it. This study shows for the first time that the yellow fever virus (YFV) NS5 protein is able to interact with U1A, a protein involved in splicing and polyadenylation. We confirmed this interaction by GST-pulldown assay and by co-immunoprecipitation in YFV-infected cells. A region between amino acids 368 and 448 was identified as the site of interaction of the NS5 protein with U1A. This region was conserved among some flaviviruses of medical importance. The implications of this interaction for flavivirus replication are discussed.

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Cariria orbiculiconiformis gen. nov. et spec. nov., a gymnosperm with gnetoid characters is described from the upper Aptian Crato Formation of the Araripe Basin in northeastern Brazil. Gross-morphology and anatomical details have been studied and characters have been discussed in respect to various seed plants. Several of these characters fit best with those of Gnetales and their putative fossil allies. However, the fossil plant cannot be assigned to any known extinct or extant group of seed plants in their current circumscription. Stem gross-morphology, xylotomical characters and epidermal features indicate a gnetophytic relationship, whereas characters of the reproductive organs are rather distinct from those found in extant taxa. The reproductive unit of the new taxon represents a triple organ consisting of two dichasial ovulate structures and one median pollen-producing structure containing smooth, monosulcate, boat-shaped pollen in-situ. Each ovulate structure consists of two distinct pairs of bracts, a sterile one at the base and a fertile one forming a terminal orbicular capsule. Stiff processes found in the apex of the ovulate structure may represent micropylar tubes of seeds, as seen in the Bennettitales-Erdtmanithecales-Gnetales group. C orbiculiconiformis gen. nov. et spec. nov. was ans herbaceous or semi-shrub-like plant that may have been adapted to the r-strategy in a stressful environment. (C) 2011 Elsevier B.V. All rights reserved.

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Vegetative and fertile shoots of a shrub-like seed plant from the late Aptian Crato Formation of Brazil are described as Cearania heterophylla Kunzmann, Mohr and Bernardes-de-Oliveira, gen. nov. et sp. nov. Anatomical details of the axes, epidermal features and separate ovulate and pollen producing organs indicate the gymnospermous nature of this plant. The vascular tissue of the axes includes tracheids with bordered pits and fiber tracheids. Vegetative shoots comprising at least three branching orders bear opposite-decussately arranged ovate to lanceolate, dorsiventrally flattened, parallelodromous, rather thick leaves that vary tremendously in size. The amphistomatic leaves bear (brachy-)paracytic stomatal complexes arranged in simple longitudinal files. The ovulate structure is interpreted as a terminally attached single globular ovule/seed surrounded by at least five to six lanceolate bracts. A terminally attached pollen-cone like structure grows on a lateral leafy shoot. The unusual character combination may indicate that the fossils belong to a hitherto unknown group with affinities to ephedroid Gnetales. Sterile shoots formerly often described as Podozamites, Nageiopsis or Lilites that are at least partly congeneric with C. heterophylla Kunzmann, Mohr and Bernardes-de-Oliveira, gen. nov. et sp. nov. had a wide geographic distribution during the Early Cretaceous. (C) 2009 Elsevier B.V. All rights reserved.

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In this paper we study n-dimensional complete spacelike submanifolds with constant normalized scalar curvature immersed in semi-Riemannian space forms. By extending Cheng-Yau`s technique to these ambients, we obtain results to such submanifolds satisfying certain conditions on both the squared norm of the second fundamental form and the mean curvature. We also characterize compact non-negatively curved submanifolds in De Sitter space of index p.

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The fractionation through bioguided antileishmanial activity of the dichloromethane extract of Cassia fistula fruits (Leguminosae) led to the isolation of the active isoflavone biochanin A, identified by spectroscopic methods. This compound showed 50% effective concentration (EC(50)) value of 18.96 mu g/mL against promastigotes of Leishmania (L.) chagasi. The cytotoxicity of this substance against peritoneal macrophages resulted in an EC(50) value of 42.58 mu g/mL. Additionally, biochanin A presented an anti-Trypanosoma-cruzi activity, resulting in an EC(50) value of 18.32 mu g/mL and a 2.4-fold more effectiveness than benznidazole. These results contribute with novel antiprotozoal compounds for future drug design studies.

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In the present investigation, we have evaluated the antileishmanial and antitrypanosomal activity of methanolic crude extracts obtained from eight species of cnidarians and of a modified steroid isolated from the octocoral Carijoa riisei. The antileishmanial activity of cnidarians crude extracts showed 50% inhibitory concentration ( IC50) values in the concentration range between 2.8 and 93.3 mu g/mL. Trypomastigotes of Trypanosoma cruzi were less susceptible to the crude extracts, with IC50 values in the concentration range between 40.9 and 117.9 mu g/mL. The steroid (18-acetoxipregna-1,4,20-trien-3-one) displayed a strong antileishmanial activity, with an IC50 value of 5.5 mu g/mL against promastigotes and 16.88 mu g/mL against intracellular amastigotes. The steroid also displayed mammalian cytotoxicity (IC50 of 10.6 mu g/mL), but no hemolytic activity was observed at the highest concentration of 12.5 mu g/mL. The antileishmanial effect of the steroid in macrophages suggested other mechanism than macrophage activation, as no upregulation of nitric oxide was observed. The antitrypanosomal activity of the steroid resulted in an IC50 value of 50.5 mu g/mL. These results indicate the potential of cnidarian natural compounds as antileishmanial drug candidates.

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Catalogue of a solo exhibition dealing with the theme of women's place in a patriarchal society.

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Differences in habitat quality can affect the abundance, distribution, and physiological status of wild birds. In Australia’s tropical savannas, grass finches live in habitats of varying land use and resultant habitat quality. Recent studies have documented regional declines in the abundance and distribution of small granivorous birds in areas affected by cattle grazing, urban development, and changes in fire frequency and timing. Small birds, especially semi-nomadic species of grass-finches, are extremely difficult to survey for changes in local abundance and productivity. Consequently, we are using a range of physiological measures to determine the susceptibility of populations to decline. We present the preliminary findings of a study using multiple condition indices to describe the health of five grass finch species living in a variety of savanna habitats. Our early results suggest that simple body condition measures such as bird mass, muscle contour, and fat storage, are not always sensitive enough to identify subtle differences in the health of individuals and populations. Measures of haematological health state, stress, and background nutritional status of finch populations appear to be associated with seasonal and site differences where body condition measures or abundance surveys would have failed to present a coherent picture. We are using habitat characteristics important to these species to help explain the differences in the health of finch populations across the North.

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This research is a narrative inquiry into the phenomenon of workplace experiences with Maori culture in the training of physical education teachers. The outcomes show that offering challenging learning and teaching environments of lived experience of Maori culture created opportunities for people to become open to accepting cultural difference.

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This paper develops a framework that uses fuzzy-set theory to measure human well-being. Fuzzy sets allow for gradual transition from one state to another while also allowing one to incorporate rules and goals, and hence are more appropriate for measuring outcomes that are ambiguous. Such ambiguity is an inherent characteristic of cross-country achieved well-being assessments. This framework is used to provide a fuzzy representation of the well known Human Development Index (HDI) and its three components. Fuzzy HDI estimates for 14 Pacific Asian countries are provided and compared with non-fuzzy estimates. Quite large differences in rankings emerge. The paper concludes by suggesting that fuzzy measures should be used more widely to measure achieved well-being outcomes.

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This paper uses 1974 to 2001 panel data for 31 sub-Saharan African and 10 Arab countries and Arellano–Bond estimations to empirically assess the impact on growth of an important indicator associated with MDG 3; namely the ratio of 15–24-year-old literate females to males. Our findings indicate that gender inequalities in literacy have a statistically significant negative effect that is robust to changes in the specification. In addition, it seems that gender inequality has a stronger effect on growth in Arab countries. Interestingly, we find that the interaction between openness to trade and gender inequality has a positive impact. This result suggests that trade-induced growth may be accompanied by greater gender inequalities.