624 research outputs found
Conformal topological Yang-Mills theory and de Sitter holography
A new topological conformal field theory in four Euclidean dimensions is
constructed from N=4 super Yang-Mills theory by twisting the whole of the
conformal group with the whole of the R-symmetry group, resulting in a theory
that is conformally invariant and has two conformally invariant BRST operators.
A curved space generalisation is found on any Riemannian 4-fold. This
formulation has local Weyl invariance and two Weyl-invariant BRST symmetries,
with an action and energy-momentum tensor that are BRST-exact. This theory is
expected to have a holographic dual in 5-dimensional de Sitter space.Comment: 34 pages, AMSTex, Reference adde
Hypoglycemic and anti-lipemic effects of the aqueous extract from Cissus sicyoides
BACKGROUND: Cissus sicyoides (Vitaceae) is a medicinal plant popularly known in Brazil as "cipó-pucá, anil-trepador, cortina, and insulina". The plant is used in several diseases, including rheumatism, epilepsy, stroke and also in the treatment of diabetes. In the present work, we studied the hypoglycemic and anti-lipemic effects of the aqueous extract prepared from fresh leaves of the plant (AECS), in the model of alloxan-induced diabetes in rats. In addition, hepatic enzyme levels were also determined. RESULTS: Results showed that the daily treatment of diabetic rats with AECS for 7 days (100 and 200 mg/kg, p.o.) significantly decreased blood glucose levels in 25 and 22% respectively, as compared to the same groups before AECS treatment. No significant changes were seen in control diabetic rats before (48 h after alloxan administration) and after distilled water treatment. While no changes were seen in total cholesterol levels, a significant decrease was observed in plasma triglyceride levels, in the alloxan-induced diabetic rats after AECS treatment with both doses, as compared to the same groups before treatment. Significant decreases in blood glucose (25%) and triglyceride levels (48%) were also observed in the alloxan-induced diabetic rats after 4 days treatment with AECS (200 mg/kg, p.o.). Aspartate (AST) and alanine (ALT) aminotransferases levels, in diabetic controls and AECS-treated rats, were in the range of reference values presented by normal rats. CONCLUSIONS: The results justify the popular use of C. sicyoides, pointing out to the potential benefit of the plant aqueous extract (AECS) in alternative medicine, in the treatment of type 2 diabetes mellitus
A complete model of the Plasmodium falciparum bifunctional enzyme dihydrofolate reductase-thymidylate synthase: a model to design new antimalarials
On the behaviour of spin-orbit connection of exoplanets
Star-planet interactions play, among other things, a crucial role in
planetary orbital configurations by circularizing orbits, aligning the star and
planet spin and synchronizing stellar rotation with orbital motions. This is
especially true for innermost giant planets, which can be schematized as binary
systems with a very large mass ratio. Despite a few examples where spin-orbit
synchronization has been obtained, there is no demographic study on synchronous
regimes in those systems yet. Here we use a sample of 1,055 stars with
innermost planet companions to show the existence of three observational loci
of star-planet synchronization regimes. Two of them have dominant fractions of
subsynchronous and supersynchronous star-planet systems, and a third less
populated regime of potentially synchronized systems. No synchronous
star-planet system with a period higher than 40 days has been detected yet.
This landscape is different from eclipsing binary systems, most of which are
synchronized. We suggest that planets in a stable asynchronous spin state
belonging to star-planet systems in a supersynchronized regime offer the most
favourable conditions for habitability.Comment: 15 pages, 1 figure in main paper, 6 supplementary figures. Published
in Nature Astronomy, May 202
Produção da banana nanicão (musa sp.) em função de tipos e doses de biofertilizantes
O uso de biofertilizantes na fruticultura vem sendo estudado em diferentes regiões do Brasil, por serem consideradas fontes de nutrientes para as culturas de fácil acesso e de baixo custo. O trabalho teve como objetivo avaliar o crescimento vegetativo da bananeira (Musa sp.) 'Nanica' submetida à aplicação via radicular de diferentes tipos e dosagens de biofertilizantes. O experimento foi conduzido, em condições de campo no Centro de Ciências Humanas e Agrárias (CCHA) da Universidade Estadual da Paraíba (UEPB), Campus Catolé do Rocha. O delineamento experimental foi de blocos casualizados no esquema fatorial 5 x 10, sendo 5 tipos de biofertilizantes (B1 = Esterco bovino (EB); B2 = EB+ farinha de rocha (FR); B3 = EB + FR+ leguminosa (L); B4 = EB+FR+ cinza de madeira (C); e B5 = EB+FR +L+C) e 10 doses (0; 0,3; 0,6; 0,9; 1,2; 1,5; 1,8; 2,1; 2,4 e 2,7 L planta-1 aplicação-1) com quatro repetições.Foramavaliado duranteo 1º e o 2º ciclodacultura, a altura da planta, o diâmetro do caule, o número de folhas ea área foliar unitária e total. Para as variáveis estudadas as dosagens de biofertilizantes não apresentaram efeitos significativos, porém os tipos de biofertilizantes foram significativos colaborando ao aumento da área foliar da planta
Sexual and individual foraging segregation in Gentoo penguins Pygoscelis papua from the Southern Ocean during an abnormal winter
Knowledge about sexual segregation and gender-specific, or indeed individual specialization, in marine organisms has improved considerably in the past decade. In this context, we tested the “Intersexual Competition Hypothesis” for penguins by investigating the feeding ecology of Gentoo penguins during their austral winter non-breeding season. We considered this during unusual environmental conditions (i.e. the year 2009 had observations of high sea surface and air temperatures) in comparison with the long term average at Bird Island, South Georgia. Through conventional (i.e. stomach contents) and stable isotopic values from red blood cells, plasma and feathers of both male and female Gentoo penguins, we showed that there were significant differences between sexes, with males feeding mainly on fish (54% by mass) followed by crustaceans (38%) whereas females fed mainly on crustaceans (89% by mass) followed by fish (4%). Themisto gaudichaudii was the most important crustacean prey for males (64% by mass; 82% by number; 53% by frequency of occurrence) and females (63% by mass; 77% by number; 89% by frequency of occurrence), contrasting with all previous studies that found Antarctic krill Euphausia superba were generally the main prey. Stable isotopic data showed that, in terms of habitat use (based on δ 13C), there were significant differences in short-term carbon signatures between males and females (based on plasma and red blood cells), suggesting that both sexes explored different habitats, with females exploring more offshore pelagic waters and males feeding more in coastal benthic waters. Based on δ 15N, males fed on significantly higher trophic level than females (based on plasma and red blood cells), in agreement with our diet results., Thus, Gentoo penguins behave in a similar manner to other non-breeding penguins species (e.g. king, macaroni and rockhopper penguins), albeit at a smaller spatial scale (as they do not disperse as these other penguins do), in that they have a wider habitat and trophic niche during the Antarctic Winter (in comparison to Summer). We also detected individual specialization in feeding/trophic levels for each gender, with certain males feeding mainly on fish and certain females mainly on crustaceans, which may be driven the prevailing environmental conditions that lead individuals to search for alternative prey, and cause sexual diet segregation. Our results provide further information to help improve understanding about sexual segregation and individual specialization of marine organisms, while contributing valuable information on the winter diet for Antarctic monitoring programs and for modelling Antarctic marine food webs
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Rarity of monodominance in hyperdiverse Amazonian forests.
Tropical forests are known for their high diversity. Yet, forest patches do occur in the tropics where a single tree species is dominant. Such "monodominant" forests are known from all of the main tropical regions. For Amazonia, we sampled the occurrence of monodominance in a massive, basin-wide database of forest-inventory plots from the Amazon Tree Diversity Network (ATDN). Utilizing a simple defining metric of at least half of the trees ≥ 10 cm diameter belonging to one species, we found only a few occurrences of monodominance in Amazonia, and the phenomenon was not significantly linked to previously hypothesized life history traits such wood density, seed mass, ectomycorrhizal associations, or Rhizobium nodulation. In our analysis, coppicing (the formation of sprouts at the base of the tree or on roots) was the only trait significantly linked to monodominance. While at specific locales coppicing or ectomycorrhizal associations may confer a considerable advantage to a tree species and lead to its monodominance, very few species have these traits. Mining of the ATDN dataset suggests that monodominance is quite rare in Amazonia, and may be linked primarily to edaphic factors
Impacto da introdução da vacina pneumocócica conjugada 10 valente nas hospitalizações por pneumonia em crianças de até 4 anos em Goiás após 2010: um estudo antes-depois
A pneumonia está entre as principais causas de morte em crianças em todo o mundo e está relacionada principalmente com o Streptococcus pneumoniae. Diante disso, a vacina pneumocócica conjugada 10-valente (PCV-10) foi criada para reduzir a morbimortalidade no Brasil ocasionado por 10 sorotipos deste patógeno. O objetivo deste trabalho será analisar o impacto da introdução da vacina PCV-10 nas hospitalizações por pneumonia em crianças de até quatro anos em Goiás, comparando os números de hospitalizações e custos do setor público de saúde do período pré-PCV-10 (2008 a 2010) com o período pós-PCV-10 (2011 a 2013). Será realizado um estudo retrospectivo analítico, tipo antes-depois, com base nos dados de hospitalizações de crianças com pneumonia fornecidos pelo banco de dados do Departamento de Informática do Sistema Único de Saúde (DATASUS). Será considerado para o período pré-PCV-10 os anos de 2008, 2009, 2010, pois a cobertura vacinal no ano de implementação da vacina (2010) foi baixa, e período pós-PCV-10 os anos de 2011, 2012 e 2013, pois as coberturas vacinais no período foram iguais ou maiores que 95%. O Teste x2 será usado para analisar as variáveis dicotômicas, enquanto teste t será utilizado para comparação das médias das variáveis dependentes nos períodos pré e pós PCV-10. Ao fim do estudo será possível determinar se o advento da PCV-10 a partir de 2010 em Goiás contribuiu de forma significativa para redução de hospitalizações e custos do setor público de saúde na faixa etária considerada
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