631 research outputs found

    Nutrição mineral de plantas ornamentais XIII: absorção de macronutrientes pelo crisùntemo, cultivar Golden Polaris

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    In order to obtain: The concentration of the macronutrients in the organs of the plant in accordance with its development; The accumulation of the nutrients by the plant. A field trial was carried out at Campina, State of SĂŁo Paulo, Brazil. Plants well fertilized (four replication in a randomized test) with 6, 27, 55, 69, 83, 97, 111 and 125 days after planting were collected and divided into stems and leaves for macronutrient analysis. The author concluded that: In the stems and leaves the nutrient concentrations are instable and vary in accordance with the growth of the plant; The concentrations of N, P, K, Mg and S diminished in the stems and leaves while the contents of P increased in the stems and Ca in the leaves; After 125 days of planting the accumulation of nutrients by the stems and leaves of a plant is: K -689 mg; N - 458 mg; Ca - 130 mg; Mg - 52 mg; P - 46 mg; S - 35 mg.Com o objetivo de determinar: As concentraçÔes dos macronutrientes, nos ĂłrgĂŁos da planta, em função de idade; A acumulação de nutrientes pela planta. Foi instalada um ensaio, no municĂ­pio de Campinas, SP, em solo tradicionalmente adubado. O delineamento estatĂ­stico foi inteiramente casualizado com quatro repetiçÔes e amostragens das plantas realizada aos 6, 27, 55, 69, 83, 97, 111 e 125 dias apĂłs o plantĂŁo, divididos em hastes e folhas que foram secas em estufa a 85°C e analisadas para N, P, K, Ca, Mg e S. Os autores concluiram que: Nas hastes e folhas, as concentraçÔes de nutrientes sĂŁo instĂĄveis e variam em função da idade da planta. As concentraçÔes de N, K, Mg, S diminuem nas hastes e nas folhas com a idade da planta, enquanto o teor de P apresenta pouca variação nas folhas, aumenta nas hastes. O Ca diminue nas hastes aumentando nas folhas. Decorridos 125 dias do plantio, o acĂșmulo de nutrientes pelas hastes de uma planta Ă©: K - 689 mg; N - 458 mg; Ca -130 mg; Mg - 52 mg; P - 46 mg e S - 35 mg

    Particle-Like Description in Quintessential Cosmology

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    Assuming equation of state for quintessential matter: p=w(z)ρp=w(z)\rho, we analyse dynamical behaviour of the scale factor in FRW cosmologies. It is shown that its dynamics is formally equivalent to that of a classical particle under the action of 1D potential V(a)V(a). It is shown that Hamiltonian method can be easily implemented to obtain a classification of all cosmological solutions in the phase space as well as in the configurational space. Examples taken from modern cosmology illustrate the effectiveness of the presented approach. Advantages of representing dynamics as a 1D Hamiltonian flow, in the analysis of acceleration and horizon problems, are presented. The inverse problem of reconstructing the Hamiltonian dynamics (i.e. potential function) from the luminosity distance function dL(z)d_{L}(z) for supernovae is also considered.Comment: 35 pages, 26 figures, RevTeX4, some applications of our treatment to investigation of quintessence models were adde

    Spatial and seasonal variations in the stable carbon isotopic composition of methane in stream sediments of eastern Amazonia

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    The stable carbon isotopic composition of methane (ή13 C-CH4) gas bubbles formed in the sediments of three Amazonian streams was determined over a 5-yr period. The study sites were two ' 'várzea' floodplain (Açu and Maicá) and one 'terra-firme' (Jamaraquá) streams. The ή 13C of sedimentary organic matter (SOM) from the surrounding vegetation and bottom sediments were also determined. The mean ή13C value of SOM was lower in the terra-firme (-29.6‰) than in the várzea stream (-23.8‰) as a result of less C4 plant deposition in the former. The ή 13C-CH4 values varied systematically both seasonally and spatially among the sites during all 5 yr of the study, in association with changes during hydrologic cycle. Overall, the variation in values of ή 13C-CH4 during the high water phase covered a narrower range of values, -63 to -56‰. Contrastively, during the low water phase the ή 13C-CH4 values for várzea and terra-firme streams are different and are in direct opposition. At this phase, the ή13C-CH4 at terra-firme stream is at least 20‰ depleted of 13C compared to várzea streams. Changes in organic matter sources, water levels and associated microbial degradation processes control the observed seasonal and spatial variations in net stable carbon isotopic composition of methane

    Vacuum Stability in Heterotic M-Theory

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    The problem of the stabilization of moduli is discussed within the context of compactified strongly coupled heterotic string theory. It is shown that all geometric, vector bundle and five-brane moduli are completely fixed, within a phenomenologically acceptable range, by non-perturbative physics. This result requires, in addition to the full space of moduli, non-vanishing Neveu-Schwarz flux, gaugino condensation with threshold corrections and the explicit form of the Pfaffians in string instanton superpotentials. The stable vacuum presented here has a negative cosmological constant. The possibility of ``lifting'' this to a metastable vacuum with positive cosmological constant is briefly discussed.Comment: 39 pages, minor correction

    An overview of anti-diabetic plants used in Gabon: Pharmacology and Toxicology

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    © 2017 Elsevier B.V. All rights reserved.Ethnopharmacological relevance: The management of diabetes mellitus management in African communities, especially in Gabon, is not well established as more than 60% of population rely on traditional treatments as primary healthcare. The aim of this review was to collect and present the scientific evidence for the use of medicinal plants that are in currect by Gabonese traditional healers to manage diabetes or hyperglycaemia based here on the pharmacological and toxicological profiles of plants with anti-diabetic activity. There are presented in order to promote their therapeutic value, ensure a safer use by population and provide some bases for further study on high potential plants reviewed. Materials and methods: Ethnobotanical studies were sourced using databases such as Online Wiley library, Pubmed, Google Scholar, PROTA, books and unpublished data including Ph.D. and Master thesis, African and Asian journals. Keywords including ‘Diabetes’ ‘Gabon’ ‘Toxicity’ ‘Constituents’ ‘hyperglycaemia’ were used. Results: A total of 69 plants currently used in Gabon with potential anti-diabetic activity have been identified in the literature, all of which have been used in in vivo or in vitro studies. Most of the plants have been studied in human or animal models for their ability to reduce blood glucose, stimulate insulin secretion or inhibit carbohydrates enzymes. Active substances have been identified in 12 out of 69 plants outlined in this review, these include Allium cepa and Tabernanthe iboga. Only eight plants have their active substances tested for anti-diabetic activity and are suitables for further investigation. Toxicological data is scarce and is dose-related to the functional parameters of major organs such as kidney and liver. Conclusion: An in-depth understanding on the pharmacology and toxicology of Gabonese anti-diabetic plants is lacking yet there is a great scope for new treatments. With further research, the use of Gabonese anti-diabetic plants is important to ensure the safety of the diabetic patients in Gabon.Peer reviewedFinal Accepted Versio

    Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in √s = 7 TeV pp collisions with the ATLAS detector

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    A search for the direct production of charginos and neutralinos in final states with three electrons or muons and missing transverse momentum is presented. The analysis is based on 4.7 fb−1 of proton–proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in three signal regions that are either depleted or enriched in Z-boson decays. Upper limits at 95% confidence level are set in R-parity conserving phenomenological minimal supersymmetric models and in simplified models, significantly extending previous results

    Jet size dependence of single jet suppression in lead-lead collisions at sqrt(s(NN)) = 2.76 TeV with the ATLAS detector at the LHC

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    Measurements of inclusive jet suppression in heavy ion collisions at the LHC provide direct sensitivity to the physics of jet quenching. In a sample of lead-lead collisions at sqrt(s) = 2.76 TeV corresponding to an integrated luminosity of approximately 7 inverse microbarns, ATLAS has measured jets with a calorimeter over the pseudorapidity interval |eta| < 2.1 and over the transverse momentum range 38 < pT < 210 GeV. Jets were reconstructed using the anti-kt algorithm with values for the distance parameter that determines the nominal jet radius of R = 0.2, 0.3, 0.4 and 0.5. The centrality dependence of the jet yield is characterized by the jet "central-to-peripheral ratio," Rcp. Jet production is found to be suppressed by approximately a factor of two in the 10% most central collisions relative to peripheral collisions. Rcp varies smoothly with centrality as characterized by the number of participating nucleons. The observed suppression is only weakly dependent on jet radius and transverse momentum. These results provide the first direct measurement of inclusive jet suppression in heavy ion collisions and complement previous measurements of dijet transverse energy imbalance at the LHC.Comment: 15 pages plus author list (30 pages total), 8 figures, 2 tables, submitted to Physics Letters B. All figures including auxiliary figures are available at http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HION-2011-02

    Exploring low-energy neutrino physics with the Coherent Neutrino Nucleus Interaction Experiment

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    The Coherent Neutrino-Nucleus Interaction Experiment (CONNIE) uses low-noise fully depleted charge-coupled devices (CCDs) with the goal of measuring low-energy recoils from coherent elastic scattering ( CE Îœ NS ) of reactor antineutrinos with silicon nuclei and testing nonstandard neutrino interactions (NSI). We report here the first results of the detector array deployed in 2016, considering an active mass 47.6 g (eight CCDs), which is operating at a distance of 30 m from the core of the Angra 2 nuclear reactor, with a thermal power of 3.8 GW. A search for neutrino events is performed by comparing data collected with the reactor on (2.1 kg-day) and reactor off (1.6 kg-day). The results show no excess in the reactor-on data, reaching the world record sensitivity down to recoil energies of about 1 keV (0.1 keV electron equivalent). A 95% confidence level limit for new physics is established at an event rate of 40 times the one expected from the standard model at this energy scale. The results presented here provide a new window to low-energy neutrino physics, allowing one to explore for the first time the energies accessible through the low threshold of CCDs. They will lead to new constraints on NSI from the CEÎœNS of antineutrinos from nuclear reactors.Fil: Aguilar Arevalo, Alexis. Universidad Nacional AutĂłnoma de MĂ©xico; MĂ©xicoFil: Bertou, Xavier Pierre Louis. ComisiĂłn Nacional de EnergĂ­a AtĂłmica. Gerencia del Área de EnergĂ­a Nuclear. Instituto Balseiro; Argentina. ComisiĂłn Nacional de EnergĂ­a AtĂłmica. Centro AtĂłmico Bariloche; Argentina. Universidad Nacional de Cuyo; Argentina. Consejo Nacional de Investigaciones CientĂ­ficas y TĂ©cnicas. Centro CientĂ­fico TecnolĂłgico Conicet - Patagonia Norte; ArgentinaFil: Bonifazi, Carla Brenda. Universidade Federal do Rio de Janeiro; Brasil. Consejo Nacional de Investigaciones CientĂ­ficas y TĂ©cnicas; ArgentinaFil: Cancelo, Gustavo Indalecio. Fermi National Accelerator Laboratory; Estados UnidosFil: Castañeda, Alejandro. Universidad Nacional AutĂłnoma de MĂ©xico; MĂ©xicoFil: Cervantes Vergara, Brenda. Universidad Nacional AutĂłnoma de MĂ©xico; MĂ©xicoFil: Chavez, Claudio. Universidad Nacional de AsunciĂłn; ParaguayFil: D’Olivo, Juan C.. Universidad Nacional AutĂłnoma de MĂ©xico; MĂ©xicoFil: Dos Anjos, JoĂŁo C.. Centro Brasileiro de Pesquisas FĂ­sicas; BrasilFil: Estrada, Juan. Fermi National Accelerator Laboratory; Estados UnidosFil: Fernandes Neto, Aldo R.. Centro Federal de EducacĂŁo TecnolĂłgica Celso Suckow Da Fonseca; BrasilFil: FernĂĄndez Moroni, Guillermo. Fermi National Accelerator Laboratory; Estados Unidos. Universidad Nacional del Sur; Argentina. Consejo Nacional de Investigaciones CientĂ­ficas y TĂ©cnicas; ArgentinaFil: Foguel, Ana. Universidade Federal do Rio de Janeiro; BrasilFil: Ford, Richard. Fermi National Accelerator Laboratory; Estados UnidosFil: Gonzalez Cuevas, Juan. Universidad Nacional de AsunciĂłn; ParaguayFil: HernĂĄndez, Pamela. Universidad Nacional AutĂłnoma de MĂ©xico; MĂ©xicoFil: Hernandez, Susana. Fermi National Accelerator Laboratory; Estados UnidosFil: Izraelevitch, Federico HernĂĄn. ComisiĂłn Nacional de EnergĂ­a AtĂłmica; Argentina. Universidad Nacional de San MartĂ­n; Argentina. Consejo Nacional de Investigaciones CientĂ­ficas y TĂ©cnicas; ArgentinaFil: Kavner, Alexander R.. University of Michigan; Estados UnidosFil: Kilminster, Ben. Universitat Zurich; SuizaFil: Kuk, Kevin. Fermi National Accelerator Laboratory; Estados UnidosFil: Lima, H.P.. Centro Brasileiro de Pesquisas FĂ­sicas; BrasilFil: Makler, MartĂ­n. Centro Brasileiro de Pesquisas FĂ­sicas; BrasilFil: Molina, Jorge. Universidad Nacional de AsunciĂłn; ParaguayFil: Mota, Philipe. Centro Brasileiro de Pesquisas FĂ­sicas; BrasilFil: Nasteva, Irina. Universidade Federal do Rio de Janeiro; BrasilFil: Paolini, Eduardo Emilio. Universidad Nacional del Sur; Argentina. Consejo Nacional de Investigaciones CientĂ­ficas y TĂ©cnicas. Centro CientĂ­fico TecnolĂłgico Conicet - BahĂ­a Blanca; ArgentinaFil: Romero, Carlos. Universidad Nacional de AsunciĂłn; ParaguayFil: Sarkis, Y.. Universidad Nacional AutĂłnoma de MĂ©xico; MĂ©xicoFil: Sofo Haro, Miguel Francisco. ComisiĂłn Nacional de EnergĂ­a AtĂłmica. Gerencia del Área de EnergĂ­a Nuclear. Instituto Balseiro; Argentina. ComisiĂłn Nacional de EnergĂ­a AtĂłmica; Argentina. Universidad Nacional de Cuyo; Argentina. Fermi National Accelerator Laboratory; Estados Unidos. Consejo Nacional de Investigaciones CientĂ­ficas y TĂ©cnicas. Centro CientĂ­fico Tecnol.conicet - Patagonia Norte. Unidad de Adm.territorial; ArgentinaFil: Souza, IruatĂŁ M. S.. Centro Brasileiro de Pesquisas FĂ­sicas; BrasilFil: Tiffenberg, Javier Sebastian. Fermi National Accelerator Laboratory; Estados Unidos. Consejo Nacional de Investigaciones CientĂ­ficas y TĂ©cnicas; ArgentinaFil: Wagner, Stefan. Centro Brasileiro de Pesquisas FĂ­sicas; Brasil. PontifĂ­cia Universidade CatĂłlica do Rio de Janeiro; Brasi

    Measurement of the polarisation of W bosons produced with large transverse momentum in pp collisions at sqrt(s) = 7 TeV with the ATLAS experiment

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    This paper describes an analysis of the angular distribution of W->enu and W->munu decays, using data from pp collisions at sqrt(s) = 7 TeV recorded with the ATLAS detector at the LHC in 2010, corresponding to an integrated luminosity of about 35 pb^-1. Using the decay lepton transverse momentum and the missing transverse energy, the W decay angular distribution projected onto the transverse plane is obtained and analysed in terms of helicity fractions f0, fL and fR over two ranges of W transverse momentum (ptw): 35 < ptw < 50 GeV and ptw > 50 GeV. Good agreement is found with theoretical predictions. For ptw > 50 GeV, the values of f0 and fL-fR, averaged over charge and lepton flavour, are measured to be : f0 = 0.127 +/- 0.030 +/- 0.108 and fL-fR = 0.252 +/- 0.017 +/- 0.030, where the first uncertainties are statistical, and the second include all systematic effects.Comment: 19 pages plus author list (34 pages total), 9 figures, 11 tables, revised author list, matches European Journal of Physics C versio
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