167 research outputs found

    TeV-scale seesaw from a multi-Higgs model

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    We suggest new simple model of generating tiny neutrino masses through a TeV-scale seesaw mechanism without requiring tiny Yukawa couplings. This model is a simple extension of the standard model by introducing extra one Higgs singlet, and one Higgs doublet with a tiny vacuum expectation value. Experimental constraints, electroweak precision data and no large flavor changing neutral currents, are satisfied since the extra doublet only has a Yukawa interaction with lepton doublets and right-handed neutrinos, and their masses are heavy of order a TeV-scale. Since active light neutrinos are Majorana particles, this model predicts a neutrinoless double beta decay.Comment: 21 pages, 8 figure

    Viabilidade de uso do híbrido Hawaii 7996 como porta-enxerto de cultuvares comerciais de tomate.

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    A técnica de enxertia é utilizada em algumas hortaliças, principalmente em áreas infestadas, para atribuir resistência a patógenos do solo, minimizando as perdas de produção de cultivares suscetíveis. Este trabalho teve como objetivo avaliar o desenvolvimento e a produtividade de plantas de tomateiro enxertadas em híbrido, tido como resistente a Ralstonia solanacearum, em comparação a pés-francos. O experimento foi desenvolvido em viveiro (produção de mudas e enxertia) e em céu aberto, no município de Cruz das Almas, Bahia, no período de outubro de 2003 a fevereiro de 2004. Utilizou-se o método de enxertia de fenda cheia, com o híbrido ‘Hawaii 7996’ como porta-enxerto e as cultivares Santa Clara, Santa Cruz Kada e Débora Plus, suscetíveis a R. solanacearum, como enxerto. O delineamento experimental foi em blocos ao acaso, com seis tratamentos (3 enxertados e 3 pés-francos), 5 repetições e 6 plantas por parcela útil. Avaliaram-se os caracteres: diâmetro do caule, altura da planta e da primeira inflorescência, distância entre inflorescências e produtividade comercial de frutos. O desenvolvimento das plantas, a produção total e a massa média dos frutos foram semelhantes para os tratamentos enxertados em relação a seus respectivos pés-francos e não houve incompatibilidade entre porta-enxerto e enxerto. A cultivar Santa Cruz Kada foi mais sensível às condições agroecológicas do município de Cruz das Almas, refletindo negativamente na produção e no peso médio dos frutos. Observou-se na enxertia com o híbrido ‘Hawaii 7996’ potencial para viabilizar a produção de tomateiros comerciais suscetíveis à murcha bacteriana, em áreas infestadas com R. solanacearum

    Locally equilibrated stress recovery for goal oriented error estimation in the extended finite element method

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    [EN] Goal oriented error estimation and adaptive procedures are essential for the accurate and efficient evaluation of finite element numerical simulations that involve complex domains. By locally improving the approximation quality, for example, by using the extended finite element method (XFEM), we can solve expensive problems which could result intractable otherwise. Here, we present an error estimation technique for enriched finite element approximations that is based on an equilibrated recovery technique, which considers the stress intensity factor as the quantity of interest. The locally equilibrated superconvergent patch recovery is used to obtain enhanced stress fields for the primal and dual problems defined to evaluate the error estimate.This work was supported by the EPSRC grant EP/G042705/1 "Increased Reliability for Industrially Relevant Automatic Crack Growth Simulation with the eXtended Finite Element Method". Stephane Bordas also thanks partial funding for his time provided by the European Research Council Starting Independent Research Grant (ERC Stg Grant Agreement No. 279578) "RealTCut Towards real time multiscale simulation of cutting in non-linear materials with applications to surgical simulation and computer guided surgery". This work has been carried out within the framework of the research project DPI2010-20542 of the Ministerio de Ciencia e Innovacion (Spain). The financial support of the FPU program (AP2008-01086), the funding from Universitat Politecnica de Valencia and Generalitat Valenciana (PROMETEO/2012/023) are also acknowledged.González Estrada, OA.; Ródenas, J.; Bordas, S.; Nadal, E.; Kerfriden, P.; Fuenmayor Fernández, FJ. (2015). Locally equilibrated stress recovery for goal oriented error estimation in the extended finite element method. Computers and Structures. 152:1-10. https://doi.org/10.1016/j.compstruc.2015.01.015S11015

    Estudos sobre a nutrição mineral do arroz: XXI - efeito das deficiências e excessos minerais na atividade da redútase de nitrato foliar e no teor de proteina dos grãos (nota prévia)

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    Rice plants, varieties IAC-164 and IAC-165 weree grown in number 2 Hoagland's solution, full strength, and with excess of Al and Cl. Nitrate reductase (RNO3) activity was assayed in the leaves one month before harvesting. When the grains were already dry, plants were harvested, the mineral contents of the organs was determined, and crude protein in the grains was also determined (semi micro Kjeldahl). Statistical analyses of the data thus obtained showed that enzymatic activity decreased when the plants were deficient in N, P, and K, as well as when the plants were deficient in N, P, and K, as well as when they had excess Al and Cl. Sulfur deficiency depressed RNO3 activity in variety IAC-164 only. Lack of Mg had the same effect in variety IAC-165. Crude protein in the grains decreased due to lack of N, P, Cu, and S, and to excess both of Al and Cl. In both varieties, however, the deficiencies of K and Mg had apparently the opposite effect. By putting together data from all treatments (except -K and -Mg) a positive correlation between leaf RNO3 activity and grain protein was found to exist.Plantas de arroz das variedades IAC-164 e IAC-165 foram cultivadas em solução nutritiva (nº 2 de Hoagland), completa com deficiência de macronutrientes e de B, Cu e Zn e com excesso de Al e Cl. No fim do ciclo, foi determinada a atividade da redútase de nitrato (RNO3) nas folhas, e após a maturação, foi determinado o teor de proteína bruta dos grãos. Nas duas variedades verificou-se que a atividade enzimática foi diminuída pelas deficiências de N, P, K e pela toxidez de Al e Cl; na IAC-164 a carência de S teve o mesmo efeito depressivo; na IAC-I65, além do efeito mencionado, houve o da falta de Mg. O teor de proteína bruta nos grãos diminuiu com as deficiências de N, P, Se Cu e com a toxidez de Al; aumentou aparentemente nos tratamentos com deficiência de K e Mg. Foi encontrada correlação entre atividade de RNO3 e teor proteico dos grãos quando os dados relativos aos tratamentos -K e -Mg não foram considerados

    Evidence for a mixed mass composition at the `ankle' in the cosmic-ray spectrum

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    We report a first measurement for ultra-high energy cosmic rays of the correlation between the depth of shower maximum and the signal in the water Cherenkov stations of air-showers registered simultaneously by the fluorescence and the surface detectors of the Pierre Auger Observatory. Such a correlation measurement is a unique feature of a hybrid air-shower observatory with sensitivity to both the electromagnetic and muonic components. It allows an accurate determination of the spread of primary masses in the cosmic-ray flux. Up till now, constraints on the spread of primary masses have been dominated by systematic uncertainties. The present correlation measurement is not affected by systematics in the measurement of the depth of shower maximum or the signal in the water Cherenkov stations. The analysis relies on general characteristics of air showers and is thus robust also with respect to uncertainties in hadronic event generators. The observed correlation in the energy range around the `ankle' at lg(E/eV)=18.519.0\lg(E/{\rm eV})=18.5-19.0 differs significantly from expectations for pure primary cosmic-ray compositions. A light composition made up of proton and helium only is equally inconsistent with observations. The data are explained well by a mixed composition including nuclei with mass A>4A > 4. Scenarios such as the proton dip model, with almost pure compositions, are thus disfavoured as the sole explanation of the ultrahigh-energy cosmic-ray flux at Earth.Comment: Published version. Added journal reference and DOI. Added Report Numbe

    High throughput simultaneous assay of atenolol and chlortalidone in combined dose tablets by liquid chromatography and capillary zone electrophoresis

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    New fast liquid chromatographic and capillary zone electrophoresis methods were developed and validated for simultaneous determination of atenolol and chlortalidone in combined dose tablets. The reversed phase HPLC method was carried out on a CN LiChrosorb® (125 x 4 mm, 5 μm) column. The CZE method was carried out on an uncoated fused-silica capillary of 30 cm x 75 μm i.d. with 25 mmol L-1 sodium tetraborate, pH 9.4. The total analysis time was <6 and <2.5 min for HPLC and CZE methods, respectively. Both methods can be used for stability studies as well.Colegio de Farmacéuticos de la Provincia de Buenos Aire
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