1,568 research outputs found

    Heritability of peach tree resistance to bacterial leaf spot.

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    The objective of this work was to evaluate the broad-sense heritability reaction to bacterial leaf spot (Xanthomonas arboricola pv. pruni), in peach tree populations obtained from directed crosses. Disease severity and defoliation of the genotypes were evaluated in field conditions, with posterior measurement of the healthy leaf area duration (HAD). The observed average heritability (0.51) indicates that the use of the evaluated genitors can be effective for the development of cultivars with higher resistance to the disease.Notas CientĂ­ficas. TĂ­tulo em portuguĂȘs: Herdabilidade de resistĂȘncia de pessegueiro Ă  bacteriose foliar

    Off-shell effects in dilepton production from hot interacting mesons

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    The production of dielectrons in reactions involving a_1 mesons and pions is studied. We compare results obtained with different phenomenological Lagrangians that have been used in connection with hadronic matter and finite nuclei. We insist on the necessity for those interactions to satisfy known empirical properties of the strong interaction. Large off-shell effects in dielectron production are found and some consequences for the interpretation of heavy ion data are outlined. We also compare with results obtained using experimentally-extracted spectral functions.Comment: 14 pages, LaTeX2e, 2 figure

    Machine learning prediction models for mitral valve repairability and mitral regurgitation recurrence in patients undergoing surgical mitral valve repair

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    Background: Mitral valve regurgitation (MR) is the most common valvular heart disease and current variables associated with MR recurrence are still controversial. We aim to develop a machine learning-based prognostic model to predict causes of mitral valve (MV) repair failure and MR recurrence. Methods: 1000 patients who underwent MV repair at our institution between 2008 and 2018 were enrolled. Patients were followed longitudinally for up to three years. Clinical and echocardiographic data were included in the analysis. Endpoints were MV repair surgical failure with consequent MV replacement or moderate/severe MR (>2+) recurrence at one-month and mod-erate/severe MR recurrence after three years. Results: 817 patients (DS1) had an echocardiographic examination at one-month while 295 (DS2) also had one at three years. Data were randomly divided into training (DS1: n = 654; DS2: n = 206) and validation (DS1: n = 164; DS2 n = 89) cohorts. For intra-operative or early MV repair failure assessment, the best area under the curve (AUC) was 0.75 and the complexity of mitral valve prolapse was the main predictor. In predicting moderate/severe recurrent MR at three years, the best AUC was 0.92 and residual MR at six months was the most important predictor. Conclusions: Machine learning algorithms may improve prognosis after MV repair procedure, thus improving indications for correct candidate selection for MV surgical repair

    Performance of clonal rootstocks for "BRS-Kampai" peach and own-rooted trees in a mild-winter region.

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    Abstract: The worldwide main peach-producing are adopting peach training systems with canopy size-controlling clonal rootstocks. However, most peach seedlings commercialised in Brazil are still on seed-propagated rootstocks, which are vigorous and heterogeneous. This study aimed to select rootstocks which induce desirable characteristics of fruit quality, yield efficiency, size control, adaptability and stability in the ‘BRS-Kampai’ grown in subtropical regions with mild winters. We used adaptability and stability methodology and multivariate selection index to determine yield components and fruit quality. The experiment was conducted in five cycles. The treatments consisted of ‘BRS-Kampai’ grafted onto 17 clonal rootstocks of Prunus spp. and own-rooted trees. The evaluated variables were yield per tree, yield per area, fruit mass, fruit diameter, fruit firmness, soluble solids content, titratable acidity, canopy volume and yield efficiency. The rootstocks ‘Ishtara¼’, ‘Genovesa’, ‘Santa Rosa’ and ‘Cadaman’ always induced low yield and low fruit quality when used as clonal rootstocks for the ‘BRS-Kampai’ and showed no potential for use as rootstocks in subtropical humid regions with mild winters. The ‘BRS-Kampai’ own-rooted peach trees or those grafted onto ‘Flordaguard’, ‘Okinawa’ are alternatives for peach cultivation under the edaphoclimatic conditions of Pato Branco-PR, although the training and pruning systems must be adjusted due to high vigour. The clonal rootstocks ‘Tsukuba-3’ and ‘Tsukuba-2’ induced the highest production performance in the canopy cultivar BRS-Kampai, combining fruit quality, yield with higher stability, and yield efficiency making them the most suitable ones among the studied rootstocks. Resumo: Sistemas de condução de pessegueiros com porta-enxertos clonais que reduzem vigor da copa sĂŁo os mais adotados mundialmente. Entretanto, no Brasil ainda se utiliza porta-enxertos propagados por sementes, que sĂŁo vigorosos e heterogĂȘneos. Este trabalho teve como objetivo selecionar porta-enxertos que induzam qualidade de frutos, eficiĂȘncia produtiva, controle de vigor, adaptabilidade e estabilidade em ‘BRS-Kampai’ cultivada em regiĂ”es subtropicais com invernos amenos. Foram utilizadas metodologias de adaptabilidade e estabilidade e Ă­ndice de seleção multivariada para determinar os componentes de produção e qualidade dos frutos. O experimento foi conduzido em cinco ciclos. Os tratamentos consistiram de pessegueiro ‘BRS-Kampai’ autoenraizado ou enxertado em 17 porta-enxertos clonais de Prunus spp. As variĂĄveis avaliadas foram produção por planta, produtividade por ĂĄrea, massa de frutos, diĂąmetro e firmeza de frutos, teor de sĂłlidos solĂșveis, acidez titulĂĄvel, volume de copa e eficiĂȘncia produtiva. Em regiĂ”es subtropicais com invernos ‘Ishtara¼’, ‘Genovesa’, ‘Santa Rosa’ e ‘Cadaman’ induziram baixa produtividade e baixa qualidade de frutos na ‘BRS-Kampai’ e nĂŁo apresentam potencial para uso como porta-enxertos. ‘BRS-Kampai’ autoenraizadas ou enxertadas em ‘Flordaguard’ e ‘Okinawa’ sĂŁo alternativas para o cultivo do pessegueiro, embora os sistemas de condução e poda devam ser ajustados devido ao alto vigor. Os porta-enxertos clonais ‘Tsukuba-3’ e ‘Tsukuba-2’ induziram o maior desempenho produtivo na ‘BRS-Kampai’, aliando qualidade de frutos, produtividade com maior estabilidade e eficiĂȘncia produtiva tornando-os os mais indicados entre os porta-enxertos estudados.TĂ­tulo em portuguĂȘs: Desempenho de porta-enxertos clonais para pessegueiro 'BRS-Kampai'e autoenraizado em regiĂŁo de inverno ameno

    Measurement of the front-end dead-time of the LHCb muon detector and evaluation of its contribution to the muon detection inefficiency

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    A method is described which allows to deduce the dead-time of the front-end electronics of the LHCb muon detector from a series of measurements performed at different luminosities at a bunch-crossing rate of 20 MHz. The measured values of the dead-time range from 70 ns to 100 ns. These results allow to estimate the performance of the muon detector at the future bunch-crossing rate of 40 MHz and at higher luminosity

    Intermediate-mass dilepton spectra and the role of secondary hadronic processes in heavy-ion collisions

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    We carry out a study of intermediate-mass (between 1 and 2.5 GeV) dilepton spectra from hadronic interactions in heavy-ion collisions. The processes considered are ππ→llˉ\pi\pi\to l{\bar l}, πρ→llˉ\pi\rho\to l{\bar l}, πa1→llˉ\pi a_1\to l{\bar l}, πω→llˉ\pi\omega\to l{\bar l}, KKˉ→llˉK{\bar K}\to l{\bar l}, and KKˉ∗+c.c→llˉK{\bar K^*}+c.c \to l{\bar l}. The elementary cross sections for those are obtained from chiral Lagrangians involving pseudoscalar, vector, and axial-vector mesons. The respective electromagnetic form factors are determined by fitting to experimental data for the reverse processes of e+e−→hadronse^+e^-\to hadrons. Based on this input we calculate cross sections and thermal dilepton emission rates and compare our results with those from other approaches. Finally we use these elementary cross sections with a relativistic transport model and calculate dilepton spectra in S+W collisions at SPS energies. The comparison of our results with experimental data from the HELIOS-3 collaboration indicates the importance of the secondary hadronic contributions to the intermediate-mass dilepton spectra.Comment: 25 pages, including 20 postscript figure

    Performance of the LHCb muon system with cosmic rays

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    The LHCb Muon system performance is presented using cosmic ray events collected in 2009. These events allowed to test and optimize the detector configuration before the LHC start. The space and time alignment and the measurement of chamber efficiency, time resolution and cluster size are described in detail. The results are in agreement with the expected detector performance.Comment: Submitted to JINST and accepte

    Measurement of the kinematic variables of beauty particles produced in 350 GeV/c π−\pi^--Cu interactions

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    Using a sample of 2626 b\=b events, produced in 350 GeV/c350\,\hbox{GeV}/c π−\pi^- interactions in a copper target, which includes 1313 events where the decays of both BB and B‟\overline{B} are well reconstructed, we measure the differential distributions with respect to xFx_F and pT2p_T^2 as well as some two-particle kinematic variables. We also compare our results with a previous experiment and with predictions based on perturbative QCD

    Performance of the LHCb muon system

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    The performance of the LHCb Muon system and its stability across the full 2010 data taking with LHC running at ps = 7 TeV energy is studied. The optimization of the detector setting and the time calibration performed with the first collisions delivered by LHC is described. Particle rates, measured for the wide range of luminosities and beam operation conditions experienced during the run, are compared with the values expected from simulation. The space and time alignment of the detectors, chamber efficiency, time resolution and cluster size are evaluated. The detector performance is found to be as expected from specifications or better. Notably the overall efficiency is well above the design requirementsComment: JINST_015P_1112 201

    Azimuthal correlation between beauty particles produced in 350 GeV/c π−\pi^{-}-Cu interactions

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    Using a sample of 10810^8 triggered events, produced in 350 GeV/c350\, \hbox{GeV}/c π−\pi^- interactions in a copper target, we have identified 2626 b\=b events. These include 1313 events where the decays of both BB and B‟\overline{B} are well reconstructed. We measure the azimuthal \hbox{correlation} between beauty particles, and compare our result with predictions based on perturbative QCD
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