550 research outputs found

    Equilibrium relative humidity and lipid oxidation in Brazil-nut, macadamia nut and soybean seed flours

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    Lipid oxidation was studied on the flour of Brazil-nut (Bertolleta excelsa), macadâmia nut (Macadamia integrifoliá) and soybean seed (Glycine max), in enviroments with controlled water activity (Aw) values of 0.51; 0.57; 0.67; 0.75; 0.79 and 0.81 at 35°C. Every 24 hours during 6 days the peroxide value was determined for each Aw in flour with enzyme inactivation (110°C, 2 hours) as well as in flour without inactivation. At low Aw values (up to 0.75) the oxidation by oxigen is the most effective mechanism of deterioration of the lipids. At higher water activity values (0.79 and 0.81) the protective effect of the humidity upon the lipids and the greater mobility of the reagents make the activity of the lipoxigenase the most important mechanism of lipid deterioration.Foi estudada a oxidação de lipídeos adicionados a farinhas de castanha do Pará (Bertholleta excelsa), de macadâmia (Macadâmia integrifolia) e de soja (Glycine max) equilibradas nas atividades de água (Aa) 0,51; 0,57; 0,67; 0,75; 0,79 e 0,81, a 35°C. O substrato utilizado para quantificar tanto a oxidação autocatalítica como a oxidação enzímica foi o óleo de soja na proporção de 20% (p:p). Dois mecanismos de oxidação de lipídeos concorrem pelo substrato nas condições estudadas. A baixos valores de Aa - de 0,51 a 0,75 - o mecanismo mais eficiente é a autoxidação devida à maior exposição do substrato ao oxigênio e à menor mobilidade dos reagentes - enzima e lipídeo - nas reações de natureza enzímica. Em valores de Aa maiores - 0,79 e 0,81 - predomina a oxidação enzímica, e atua a proteção do substrato pela água, frente à ação do oxigênio. O índice de peróxido medido no transcurso de 6 dias apresenta máximos e mínimos devidos a reações secundárias atuando sobre produtos das reações primárias

    Static Observers in Curved Spaces and Non-inertial Frames in Minkowski Spacetime

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    Static observers in curved spacetimes may interpret their proper acceleration as the opposite of a local gravitational field (in the Newtonian sense). Based on this interpretation and motivated by the equivalence principle, we are led to investigate congruences of timelike curves in Minkowski spacetime whose acceleration field coincides with the acceleration field of static observers of curved spaces. The congruences give rise to non-inertial frames that are examined. Specifically we find, based on the locality principle, the embedding of simultaneity hypersurfaces adapted to the non-inertial frame in an explicit form for arbitrary acceleration fields. We also determine, from the Einstein equations, a covariant field equation that regulates the behavior of the proper acceleration of static observers in curved spacetimes. It corresponds to an exact relativistic version of the Newtonian gravitational field equation. In the specific case in which the level surfaces of the norm of the acceleration field of the static observers are maximally symmetric two-dimensional spaces, the energy-momentum tensor of the source is analyzed.Comment: 28 pages, 4 figures

    Use of the electronic tongue as a tool for the characterization of Melipona scutellaris Latreille honey

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    This study aimed to characterize honey of Melipona scutellaris regarding its physicochemical parameters using the electronic tongue (e-tongue) technique combined with the multivariate statistical analysis for honey differentiation. Physicochemical parameters were evaluated following official methods of chemical analyses. A potentiometric electronic tongue with 16 cross-sensitivity sensors was used for the analysis. The Principal Component Analysis and the Cluster Analysis distinguished two groups for the sample set in the evaluation of physicochemical parameters, similar to results found using the electronic tongue. We verified a correlation greater than 0.70 between the profile of potentiometric signals and values of pH, ashes, electrical conductivity, HMF, diastase activity, reducing sugars, and apparent sucrose. The combined use of the electronic tongue with the statistical analysis showed the similarity between samples through the formation of two groups of the sample set. The electronic tongue may be used as a complement to traditional techniques of analyses to determine honey physicochemical parameters, constituting a promising tool in association with the multivariate statistical analysis.This study was financed in part by the “Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brasil” (CAPES) - Finance Code 001 and by the “Fundação de Amparo à Pesquisa do Estado da Bahia” (FAPESB) - under grant PAM0004/2014. We thank “Conselho Nacional de Desenvolvimento Científico e Tecnológico” (CNPq) for the scholarship granted to CALC (No. 305885/2017-0).info:eu-repo/semantics/publishedVersio

    Psychometric assessment of the short-form Child Perceptions Questionnaire: an international collaborative study.

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    OBJECTIVE: To examine the factor structure and other psychometric characteristics of the most commonly used child oral-health-related quality-of-life (OHRQoL) measure (the 16-item short-form CPQ11-14 ) in a large number of children (N = 5804) from different settings and who had a range of caries experience and associated impacts. METHODS: Secondary data analyses used subnational epidemiological samples of 11- to 14-year-olds in Australia (N = 372), New Zealand (three samples: 352, 202, 429), Brunei (423), Cambodia (244), Hong Kong (542), Malaysia (439), Thailand (220, 325), England (88, 374), Germany (1055), Mexico (335) and Brazil (404). Confirmatory factor analysis (CFA) was used to examine the factor structure of the CPQ11-14 across the combined sample and within four regions (Australia/NZ, Asia, UK/Europe and Latin America). Item impact and internal reliability analysis were also conducted. RESULTS: Caries experience varied, with mean DMFT scores ranging from 0.5 in the Malaysian sample to 3.4 in one New Zealand sample. Even more variation was noted in the proportion reporting only fair or poor oral health; this was highest in the Cambodian and Mexican samples and lowest in the German sample and one New Zealand sample. One in 10 reported that their oral health had a marked impact on their life overall. The CFA across all samples revealed two factors with eigenvalues greater than 1. The first involved all items in the oral symptoms and functional limitations subscales; the second involved all emotional well-being and social well-being items. The first was designated the 'symptoms/function' subscale, and the second was designated the 'well-being' subscale. Cronbach's alpha scores were 0.72 and 0.84, respectively. The symptoms/function subscale contained more of the items with greater impact, with the item 'Food stuck in between your teeth' having greatest impact; in the well-being subscale, the 'Felt shy or embarrassed' item had the greatest impact. Repeating the analyses by world region gave similar findings. CONCLUSION: The CPQ11-14 performed well cross-sectionally in the largest analysis of the scale in the literature to date, with robust and mostly consistent psychometric characteristics, albeit with two underlying factors (rather than the originally hypothesized four-factor structure). It appears to be a sound, robust measure which should be useful for research, practice and policy

    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

    Observation of a new chi_b state in radiative transitions to Upsilon(1S) and Upsilon(2S) at ATLAS

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    The chi_b(nP) quarkonium states are produced in proton-proton collisions at the Large Hadron Collider (LHC) at sqrt(s) = 7 TeV and recorded by the ATLAS detector. Using a data sample corresponding to an integrated luminosity of 4.4 fb^-1, these states are reconstructed through their radiative decays to Upsilon(1S,2S) with Upsilon->mu+mu-. In addition to the mass peaks corresponding to the decay modes chi_b(1P,2P)->Upsilon(1S)gamma, a new structure centered at a mass of 10.530+/-0.005 (stat.)+/-0.009 (syst.) GeV is also observed, in both the Upsilon(1S)gamma and Upsilon(2S)gamma decay modes. This is interpreted as the chi_b(3P) system.Comment: 5 pages plus author list (18 pages total), 2 figures, 1 table, corrected author list, matches final version in Physical Review Letter

    Search for displaced vertices arising from decays of new heavy particles in 7 TeV pp collisions at ATLAS

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    We present the results of a search for new, heavy particles that decay at a significant distance from their production point into a final state containing charged hadrons in association with a high-momentum muon. The search is conducted in a pp-collision data sample with a center-of-mass energy of 7 TeV and an integrated luminosity of 33 pb^-1 collected in 2010 by the ATLAS detector operating at the Large Hadron Collider. Production of such particles is expected in various scenarios of physics beyond the standard model. We observe no signal and place limits on the production cross-section of supersymmetric particles in an R-parity-violating scenario as a function of the neutralino lifetime. Limits are presented for different squark and neutralino masses, enabling extension of the limits to a variety of other models.Comment: 8 pages plus author list (20 pages total), 8 figures, 1 table, final version to appear in Physics Letters

    Measurement of the inclusive isolated prompt photon cross-section in pp collisions at sqrt(s)= 7 TeV using 35 pb-1 of ATLAS data

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    A measurement of the differential cross-section for the inclusive production of isolated prompt photons in pp collisions at a center-of-mass energy sqrt(s) = 7 TeV is presented. The measurement covers the pseudorapidity ranges |eta|<1.37 and 1.52<=|eta|<2.37 in the transverse energy range 45<=E_T<400GeV. The results are based on an integrated luminosity of 35 pb-1, collected with the ATLAS detector at the LHC. The yields of the signal photons are measured using a data-driven technique, based on the observed distribution of the hadronic energy in a narrow cone around the photon candidate and the photon selection criteria. The results are compared with next-to-leading order perturbative QCD calculations and found to be in good agreement over four orders of magnitude in cross-section.Comment: 7 pages plus author list (18 pages total), 2 figures, 4 tables, final version published in Physics Letters

    Measurement of D*+/- meson production in jets from pp collisions at sqrt(s) = 7 TeV with the ATLAS detector

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    This paper reports a measurement of D*+/- meson production in jets from proton-proton collisions at a center-of-mass energy of sqrt(s) = 7 TeV at the CERN Large Hadron Collider. The measurement is based on a data sample recorded with the ATLAS detector with an integrated luminosity of 0.30 pb^-1 for jets with transverse momentum between 25 and 70 GeV in the pseudorapidity range |eta| < 2.5. D*+/- mesons found in jets are fully reconstructed in the decay chain: D*+ -> D0pi+, D0 -> K-pi+, and its charge conjugate. The production rate is found to be N(D*+/-)/N(jet) = 0.025 +/- 0.001(stat.) +/- 0.004(syst.) for D*+/- mesons that carry a fraction z of the jet momentum in the range 0.3 < z < 1. Monte Carlo predictions fail to describe the data at small values of z, and this is most marked at low jet transverse momentum.Comment: 10 pages plus author list (22 pages total), 5 figures, 1 table, matches published version in Physical Review
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