285 research outputs found

    MacrĂłfitas aquĂĄticas do sistema lacustre do Vale do Rio Doce, Minas Gerais, Brasil

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    Resumo Esta pesquisa trata da composição e da ocorrĂȘncia de espĂ©cies de macrĂłfitas aquĂĄticas em ĂĄrea de proteção ambiental e ĂĄreas nĂŁo protegidas, que compĂ”em o conjunto de lagos do Vale do Rio Doce em Minas Gerais, terceiro maior sistema lacustre brasileiro. As informaçÔes foram levantadas a partir de publicaçÔes, material depositado em herbĂĄrios e coletas botĂąnicas entre os anos de 2007 e 2010, em ambientes aquĂĄticos localizados no Parque Estadual do Rio Doce (PERD) e zona de amortecimento. Foram registradas 184 espĂ©cies pertencentes a distintos grupos taxonĂŽmicos, hĂĄbitos e formas biolĂłgicas, sendo aqui proposta a criação de uma nova categoria destas, designada embalsada, para contemplar plantas que se estabelecem em ilhas flutuantes. A pesquisa contribuiu com 152 novas citaçÔes para o Vale do Rio Doce em Minas Gerais, com dois primeiros registros nesse estado e com a descrição de uma espĂ©cie inĂ©dita para a ciĂȘncia. A similaridade florĂ­stica entre ĂĄreas protegidas e nĂŁo protegidas indicou que o PERD guarda 74% das espĂ©cies de macrĂłfitas aquĂĄticas encontradas. Entretanto, 26% do total de espĂ©cies estĂŁo desprotegidas, pois nĂŁo ocorrem nessa unidade de conservação

    Measurements of differential production cross sections for a Z boson in association with jets in pp collisions at root s=8 TeV

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    Search for leptophobic Z ' bosons decaying into four-lepton final states in proton-proton collisions at root s=8 TeV

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    Search for black holes and other new phenomena in high-multiplicity final states in proton-proton collisions at root s=13 TeV

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    Search for heavy resonances decaying into a vector boson and a Higgs boson in final states with charged leptons, neutrinos, and b quarks

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    Search for high-mass diphoton resonances in proton-proton collisions at 13 TeV and combination with 8 TeV search

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    Measurement of the azimuthal anisotropy of Y(1S) and Y(2S) mesons in PbPb collisions at √S^{S}NN = 5.02 TeV

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    The second-order Fourier coefficients (υ2_{2}) characterizing the azimuthal distributions of ΄(1S) and ΄(2S) mesons produced in PbPb collisions at sNN\sqrt{s_{NN}} = 5.02 TeV are studied. The ΄mesons are reconstructed in their dimuon decay channel, as measured by the CMS detector. The collected data set corresponds to an integrated luminosity of 1.7 nb−1^{-1}. The scalar product method is used to extract the υ2_{2} coefficients of the azimuthal distributions. Results are reported for the rapidity range |y| < 2.4, in the transverse momentum interval 0 < pT_{T} < 50 GeV/c, and in three centrality ranges of 10–30%, 30–50% and 50–90%. In contrast to the J/ψ mesons, the measured υ2_{2} values for the ΄ mesons are found to be consistent with zero

    Performance of the CMS Level-1 trigger in proton-proton collisions at √s = 13 TeV

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    At the start of Run 2 in 2015, the LHC delivered proton-proton collisions at a center-of-mass energy of 13\TeV. During Run 2 (years 2015–2018) the LHC eventually reached a luminosity of 2.1× 1034^{34} cm−2^{-2}s−1^{-1}, almost three times that reached during Run 1 (2009–2013) and a factor of two larger than the LHC design value, leading to events with up to a mean of about 50 simultaneous inelastic proton-proton collisions per bunch crossing (pileup). The CMS Level-1 trigger was upgraded prior to 2016 to improve the selection of physics events in the challenging conditions posed by the second run of the LHC. This paper describes the performance of the CMS Level-1 trigger upgrade during the data taking period of 2016–2018. The upgraded trigger implements pattern recognition and boosted decision tree regression techniques for muon reconstruction, includes pileup subtraction for jets and energy sums, and incorporates pileup-dependent isolation requirements for electrons and tau leptons. In addition, the new trigger calculates high-level quantities such as the invariant mass of pairs of reconstructed particles. The upgrade reduces the trigger rate from background processes and improves the trigger efficiency for a wide variety of physics signals
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