2,479 research outputs found

    The strange and charm quark contributions to the anomalous magnetic moment of the muon from lattice QCD

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    AbstractWe describe a new technique (published in [1]) to determine the contribution to the anomalous magnetic moment of the muon coming from the hadronic vacuum polarisation using lattice QCD. Our method uses PadĂ© approximants to reconstruct the Adler function from its derivatives at q2=0. These are obtained simply and accurately from time-moments of the vector current-current correlator at zero spatial momentum. We test the method using strange quark correlators calculated on MILC Collaboration's nf=2+1+1 HISQ ensembles at multiple values of the lattice spacing, multiple volumes and multiple light sea quark masses (including physical pion mass configurations). We find the (connected) contribution to the anomalous moment from the strange quark vacuum polarisation to be aÎŒs=53.41(59)×10−10, and the contribution from charm quarks to be aÎŒc=14.42(39)×10−10−1% accuracy is achieved for the strange quark contribution. The extension of our method to the light quark contribution and to that from the quark-line disconnected diagram is straightforward

    Does IQ influence association between working memory and adhd symptoms in young adults?

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    Objective: This study examined the association between WM and ADHD symptoms in young adults and whether IQ-score influenced this association. Method: Data from the 1993 Pelotas (Brazil) Birth Cohort Study were analyzed (N = 2,845). Working memory and ADHD symptoms were collected at 22 years. IQ was examined at age 18. Poisson regression with robust variance was used to assess the associations between working memory and ADHD symptoms. We also evaluated whether IQ modified associations between working memory and ADHD symptoms. Results: Working memory was negatively associated with Inattention symptoms of ADHD. The association between working memory and hyperactivity-impulsivity symptoms of ADHD varied by IQ. Conclusions: This study provides new insights to theories about the relationship between WM and ADHD symptoms as well as the development of interventions aimed at improving the performance of WM in ADHD

    Enzyme-assisted modification of flavonoids from Matricaria chamomilla: antioxidant activity and inhibitory effect on digestive enzymes

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    Matricaria chamomilla L. contains antioxidant flavonoids that can have their bioactivity enhanced by enzymatic hydrolysis of specific glycosyl groups. This study implements an untargeted metabolomics approach based on ultra-performance liquid chromatography coupled with electrospray ionisation quadrupole time-of-flight mass spectrometry technique operating in MSE mode (UPLC-QTOF-MSE) and spectrophotometric analysis of chamomile aqueous infusions, before and after hydrolysis by hesperidinase and ?-galactosidase. Several phenolic compounds were altered in the enzymatically treated infusion, with the majority being flavonoid derivatives of apigenin, esculetin, and quercetin. Although enzymatically modifying the infusion only led to a small increase in antioxidant activity (DPPH? method), its inhibitory effect on pancreatic lipase was of particular interest. The enzymatically treated infusion exhibited a greater inhibitory effect (EC50 of 35.6??M) than unmodified infusion and kinetic analysis suggested mixed inhibition of pancreatic lipase. These results are of great relevance due to the potential of enzymatically treated functional foods in human health3514249CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQCOORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPESFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESPsem informaçãosem informação2012/20393–

    Definição e diagnóstico de neuropatia de fibras finas: consenso do Departamento Científico de Neuropatias Periféricas da Academia Brasileira de Neurologia

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    The aim of this study was to describe the results of a Brazilian Consensus on Small Fiber Neuropathy (SFN). Fifteen neurologists (members of the Brazilian Academy of Neurology) reviewed a preliminary draft. Eleven panelists got together in the city of Fortaleza to discuss and finish the text for the manuscript submission. Small fiber neuropathy can be defined as a subtype of neuropathy characterized by selective involvement of unmyelinated or thinly myelinated sensory fibers. Its clinical picture includes both negative and positive manifestations: sensory (pain/ dysesthesias/pruritus) or combined sensory and autonomic complaints, associated with an almost entirely normal neurological examination. Standard electromyography is normal. A growing list of medical conditions is associated with SFN. The classification of SFN may also serve as a useful terminology to uncover minor discrepancies in the normal values from different neurophysiology laboratories. Several techniques may disclose sensory and/or autonomic impairment. Further studies are necessary to refine these techniques and develop specific therapies.O objetivo deste estudo Ă© descrever os resultados de um Consenso Brasileiro sobre Neuropatia de Fibras Finas (NFF). Quinze neurologistas (membros da Academia Brasileira de Neurologia) revisaram uma versĂŁo preliminar do artigo. Onze panelistas se reuniram na cidade de Fortaleza para discutir e terminar o texto para a submissĂŁo do manuscrito. NFF pode ser definida como um subtipo de neuropatia caracterizada pelo envolvimento seletivo de fibras sensitivas amielĂ­nicas ou pouco mielinizadas. Seu quadro clĂ­nico inclui manifestaçÔes negativas e positivas: sensitivas (dor/disestesias/prurido) ou queixas sensitivas e autonĂŽmicas combinadas, associadas a exame neurolĂłgico quase totalmente normal. A eletromiografia convencional Ă© normal. Uma lista crescente de condiçÔes mĂ©dicas causa NFF. NFF tambĂ©m pode servir como uma terminologia Ăștil para referenciar pequenas discrepĂąncias nos valores normais de diferentes laboratĂłrios de neurofisiologia. Diferentes tĂ©cnicas podem evidenciar anormalidades sensitivas e/ou autonĂŽmicas. SĂŁo necessĂĄrios mais estudos para refinĂĄ-las e para o desenvolvimento de terapias especĂ­ficas.Univ Fed Ceara, Fac Med, Hosp Univ Walter Cantidio, Fortaleza, CE, BrazilUniv Sao Paulo, Fac Med Ribeirao Preto, Dept Neurociencias & Hosp Clin, Ribeirao Preto, SP, BrazilUniv Fed Santa Catarina, Florianopolis, SC, BrazilUniv Fed Rio de Janeiro, Dept Neurol, Rio De Janeiro, RJ, BrazilUniv Fed Cariri, Barbalha, CE, BrazilUniv Fed Fluminense, Fac Med, Dept Neurol, Niteroi, RJ, BrazilUniv Estadual Campinas, Dept Neurol, Campinas, SP, BrazilUniv Regiao Joinville, Joinville, SC, BrazilUniv Fed Sao Paulo, Dept Neurol, Sao Paulo, SP, BrazilUniv Fed Uberlandia, Fac Med, Uberlandia, MG, BrazilHosp Moinhos De Vento, Porto Alegre, RS, BrazilUniv Fed Sao Paulo, Dept Neurol, Sao Paulo, SP, BrazilWeb of Scienc

    Measurement of χ c1 and χ c2 production with s√ = 7 TeV pp collisions at ATLAS

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    The prompt and non-prompt production cross-sections for the χ c1 and χ c2 charmonium states are measured in pp collisions at s√ = 7 TeV with the ATLAS detector at the LHC using 4.5 fb−1 of integrated luminosity. The χ c states are reconstructed through the radiative decay χ c → J/ÏˆÎł (with J/ψ → ÎŒ + ÎŒ −) where photons are reconstructed from Îł → e + e − conversions. The production rate of the χ c2 state relative to the χ c1 state is measured for prompt and non-prompt χ c as a function of J/ψ transverse momentum. The prompt χ c cross-sections are combined with existing measurements of prompt J/ψ production to derive the fraction of prompt J/ψ produced in feed-down from χ c decays. The fractions of χ c1 and χ c2 produced in b-hadron decays are also measured

    Measurement of the cross-section and charge asymmetry of WW bosons produced in proton-proton collisions at s=8\sqrt{s}=8 TeV with the ATLAS detector

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    This paper presents measurements of the W+→Ό+ÎœW^+ \rightarrow \mu^+\nu and W−→Ό−ΜW^- \rightarrow \mu^-\nu cross-sections and the associated charge asymmetry as a function of the absolute pseudorapidity of the decay muon. The data were collected in proton--proton collisions at a centre-of-mass energy of 8 TeV with the ATLAS experiment at the LHC and correspond to a total integrated luminosity of 20.2~\mbox{fb^{-1}}. The precision of the cross-section measurements varies between 0.8% to 1.5% as a function of the pseudorapidity, excluding the 1.9% uncertainty on the integrated luminosity. The charge asymmetry is measured with an uncertainty between 0.002 and 0.003. The results are compared with predictions based on next-to-next-to-leading-order calculations with various parton distribution functions and have the sensitivity to discriminate between them.Comment: 38 pages in total, author list starting page 22, 5 figures, 4 tables, submitted to EPJC. All figures including auxiliary figures are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/STDM-2017-13

    Measurement of the production of a W boson in association with a charm quark in pp collisions at √s = 7 TeV with the ATLAS detector

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    The production of a W boson in association with a single charm quark is studied using 4.6 fb−1 of pp collision data at s√ = 7 TeV collected with the ATLAS detector at the Large Hadron Collider. In events in which a W boson decays to an electron or muon, the charm quark is tagged either by its semileptonic decay to a muon or by the presence of a charmed meson. The integrated and differential cross sections as a function of the pseudorapidity of the lepton from the W-boson decay are measured. Results are compared to the predictions of next-to-leading-order QCD calculations obtained from various parton distribution function parameterisations. The ratio of the strange-to-down sea-quark distributions is determined to be 0.96+0.26−0.30 at Q 2 = 1.9 GeV2, which supports the hypothesis of an SU(3)-symmetric composition of the light-quark sea. Additionally, the cross-section ratio σ(W + +cÂŻÂŻ)/σ(W − + c) is compared to the predictions obtained using parton distribution function parameterisations with different assumptions about the s−sÂŻÂŻÂŻ quark asymmetry

    Measurements of fiducial and differential cross sections for Higgs boson production in the diphoton decay channel at s√=8 TeV with ATLAS

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    Measurements of fiducial and differential cross sections are presented for Higgs boson production in proton-proton collisions at a centre-of-mass energy of s√=8 TeV. The analysis is performed in the H → γγ decay channel using 20.3 fb−1 of data recorded by the ATLAS experiment at the CERN Large Hadron Collider. The signal is extracted using a fit to the diphoton invariant mass spectrum assuming that the width of the resonance is much smaller than the experimental resolution. The signal yields are corrected for the effects of detector inefficiency and resolution. The pp → H → γγ fiducial cross section is measured to be 43.2 ±9.4(stat.) − 2.9 + 3.2 (syst.) ±1.2(lumi)fb for a Higgs boson of mass 125.4GeV decaying to two isolated photons that have transverse momentum greater than 35% and 25% of the diphoton invariant mass and each with absolute pseudorapidity less than 2.37. Four additional fiducial cross sections and two cross-section limits are presented in phase space regions that test the theoretical modelling of different Higgs boson production mechanisms, or are sensitive to physics beyond the Standard Model. Differential cross sections are also presented, as a function of variables related to the diphoton kinematics and the jet activity produced in the Higgs boson events. The observed spectra are statistically limited but broadly in line with the theoretical expectations

    Search for dark matter in events with heavy quarks and missing transverse momentum in pp collisions with the ATLAS detector

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    This article reports on a search for dark matterpair production in association with bottom or top quarks in20.3fb−1ofppcollisions collected at√s=8TeVbytheATLAS detector at the LHC. Events with large missing trans-verse momentum are selected when produced in associationwith high-momentum jets of which one or more are identifiedas jets containingb-quarks. Final states with top quarks areselected by requiring a high jet multiplicity and in some casesa single lepton. The data are found to be consistent with theStandard Model expectations and limits are set on the massscale of effective field theories that describe scalar and tensorinteractions between dark matter and Standard Model par-ticles. Limits on the dark-matter–nucleon cross-section forspin-independent and spin-dependent interactions are alsoprovided. These limits are particularly strong for low-massdark matter. Using a simplified model, constraints are set onthe mass of dark matter and of a coloured mediator suitableto explain a possible signal of annihilating dark matter
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