1,974 research outputs found

    NPK combinations mitigate the deleterious effects of salt stress on the morphophysiology of West Indian Cherry

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    Under salt stress, plant growth and development are negatively affected due to physiological changes,requiring strategies such as fertilization management to minimize these effects. In this scenario, this study aimedto evaluate the effect of combinations of nitrogen, phosphorus, and potassium on the growth, leaf waterstatus, electrolyte leakage, and gas exchange of West Indian Cherry grown under water stress in the secondyear of production. The experiment was conducted in a protected environment in Campina Grande - PB.The treatments were distributed in a randomized block design with a 2 × 10 factorial arrangement with threereplications corresponding to two electrical conductivity levels of irrigation water– ECw (0.6 and 4.0 dS m-1)and ten combinations of fertilization with nitrogen, phosphorus, and potassium (80-100-100; 100-100-100; 120-100-100; 140-100-100; 100-80-100; 100-120-100; 100-140-100; 100-100-80; 100-100-120, and 100-100-140% of therecommendation in the second year of production). Irrigation with the ECw of 4.0 dS m-1 negatively affectedplant growth, the leaf water status, electrolyte leakage, and the leaf gas exchange of West Indian Cherry.However, the 40% increase (C4 -140-100-100% of the recommended N-P2O5-K2O level) in the nitrogen levelmitigated the deleterious effects of salt stress on the relative water content, internal CO2 concentration, and theCO2 assimilation rate of West Indian Cherry plants in the second year of production.Under salt stress, plant growth and development are negatively affected due to physiological changes,requiring strategies such as fertilization management to minimize these effects. In this scenario, this study aimedto evaluate the effect of combinations of nitrogen, phosphorus, and potassium on the growth, leaf waterstatus, electrolyte leakage, and gas exchange of West Indian Cherry grown under water stress in the secondyear of production. The experiment was conducted in a protected environment in Campina Grande - PB.The treatments were distributed in a randomized block design with a 2 × 10 factorial arrangement with threereplications corresponding to two electrical conductivity levels of irrigation water– ECw (0.6 and 4.0 dS m-1)and ten combinations of fertilization with nitrogen, phosphorus, and potassium (80-100-100; 100-100-100; 120-100-100; 140-100-100; 100-80-100; 100-120-100; 100-140-100; 100-100-80; 100-100-120, and 100-100-140% of therecommendation in the second year of production). Irrigation with the ECw of 4.0 dS m-1 negatively affectedplant growth, the leaf water status, electrolyte leakage, and the leaf gas exchange of West Indian Cherry.However, the 40% increase (C4 -140-100-100% of the recommended N-P2O5-K2O level) in the nitrogen levelmitigated the deleterious effects of salt stress on the relative water content, internal CO2 concentration, and theCO2 assimilation rate of West Indian Cherry plants in the second year of production.

    ITASAT-2: ConOps Review and Near-Term Challenges

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    ITASAT-2 is a Brazil-United States mission to study ionospheric phenomena that occur in low orbit and to develop and demonstrate capabilities in geolocation. Brazil will be responsible for the spacecraft development, integration and testing of the CubeSat and the US partners will provide the space weather payloads. The geolocation payload and radiation measurement instrument is intended to be provided by Brazil partners. To be able to accommodate the expected payloads and the required subsystems a 12 U CubeSat is foreseen. This works presents the ongoing work of ITASAT-2 mission covering the Concept of Operation and expected challenges identified for mission development, maneuvers and propulsion, commissioning and operations. The intended partners for the mission are NASA Marshall Space Flight Center, Utah State University, University of Texas at Dallas, Aerospace Corporation, Brazilian Universities and institutes

    Aplicação de quitosana no cultivo do algodoeiro de fibra colorida ‘BRS Jade’ sob restrição hídrica

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    Na região semiárida do Nordeste brasileiro é comum a ocorrência de variação temporal e espacial de chuvas, resultando em limitações hídricas que afetam a produção, especialmente do algodoeiro. Nesse sentido, a quitosana pode ser uma estratégia para minimizar os efeitos do déficit hídrico, melhorando a absorção de água e nutrientes. Objetivou-se com este estudo avaliar o efeito de concentrações de quitosana como atenuante da restrição hídrica no cultivo do algodoeiro de fibra naturalmente colorida ‘BRS Jade’. As plantas foram conduzidas em lisímetros de drenagem sob condições de casa de vegetação.  Utilizou-se o delineamento inteiramente casualizado em esquema fatorial 2 × 4, sendo duas lâminas de irrigação (100 e 50% da necessidade hídrica da cultura) e quatro concentrações de quitosana (0,0; 0,25; 0,50 e 0,75 g L-1) com três repetições e uma planta por parcela. A restrição hídrica em 50% da lâmina reduziu o conteúdo relativo de água, a síntese de pigmentos fotossintéticos e a massa de algodão em caroço. Entretanto, a aplicação foliar de quitosana entre as concentrações de 0,25 e 0,50 g L-1 amenizou os efeitos deletérios da restrição hídrica sobre o teor de clorofila b, carotenoides, diâmetro do caule, área foliar, peso de 100 sementes, peso médio de capulho, massa de algodão em caroço, fitomassa seca total de capulhos, fitomassa seca do caule, da folha e da parte aérea do algodoeiro de fibra colorida ‘BRS Jade’

    The ITA Space Center and Its Role in Space Education in Brazil

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    This paper presents the ITA Space Center and its mission in the formation of human resources and in the research and development of space products. In 2012 the first aerospace engineers were graduated at ITA, and since then many efforts have been done to improve the engineering education. The first effort was the development of AESP-14 CubeSat project, then the development and launch of ITASAT, a 6U CubeSat. These two projects showed that small satellites projects provide a good learning approach once students were deeply involved in the development process. These two projects opened the opportunity for the creation of the ITA Space Center (CEI -acronym for Centro Espacial ITA in Portuguese). Inside its facilities the ITA Space Center provides capabilities for the development of small space projects such as electronics, software engineering, mechanical design, and simulation with the aid of systems engineering and project management. By means of the graduate and undergraduate programs the ITA Space Center is providing education and integration with the industries and other partner organizations. In developing and delivering space products, and fostering higher education in space, the ITA Space Center is accomplishing of its proposed mission

    Jet energy measurement with the ATLAS detector in proton-proton collisions at root s=7 TeV

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    The jet energy scale and its systematic uncertainty are determined for jets measured with the ATLAS detector at the LHC in proton-proton collision data at a centre-of-mass energy of √s = 7TeV corresponding to an integrated luminosity of 38 pb-1. Jets are reconstructed with the anti-kt algorithm with distance parameters R=0. 4 or R=0. 6. Jet energy and angle corrections are determined from Monte Carlo simulations to calibrate jets with transverse momenta pT≥20 GeV and pseudorapidities {pipe}η{pipe}<4. 5. The jet energy systematic uncertainty is estimated using the single isolated hadron response measured in situ and in test-beams, exploiting the transverse momentum balance between central and forward jets in events with dijet topologies and studying systematic variations in Monte Carlo simulations. The jet energy uncertainty is less than 2. 5 % in the central calorimeter region ({pipe}η{pipe}<0. 8) for jets with 60≤pT<800 GeV, and is maximally 14 % for pT<30 GeV in the most forward region 3. 2≤{pipe}η{pipe}<4. 5. The jet energy is validated for jet transverse momenta up to 1 TeV to the level of a few percent using several in situ techniques by comparing a well-known reference such as the recoiling photon pT, the sum of the transverse momenta of tracks associated to the jet, or a system of low-pT jets recoiling against a high-pT jet. More sophisticated jet calibration schemes are presented based on calorimeter cell energy density weighting or hadronic properties of jets, aiming for an improved jet energy resolution and a reduced flavour dependence of the jet response. The systematic uncertainty of the jet energy determined from a combination of in situ techniques is consistent with the one derived from single hadron response measurements over a wide kinematic range. The nominal corrections and uncertainties are derived for isolated jets in an inclusive sample of high-pT jets. Special cases such as event topologies with close-by jets, or selections of samples with an enhanced content of jets originating from light quarks, heavy quarks or gluons are also discussed and the corresponding uncertainties are determined. © 2013 CERN for the benefit of the ATLAS collaboration

    Measurement of the inclusive and dijet cross-sections of b-jets in pp collisions at sqrt(s) = 7 TeV with the ATLAS detector

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    The inclusive and dijet production cross-sections have been measured for jets containing b-hadrons (b-jets) in proton-proton collisions at a centre-of-mass energy of sqrt(s) = 7 TeV, using the ATLAS detector at the LHC. The measurements use data corresponding to an integrated luminosity of 34 pb^-1. The b-jets are identified using either a lifetime-based method, where secondary decay vertices of b-hadrons in jets are reconstructed using information from the tracking detectors, or a muon-based method where the presence of a muon is used to identify semileptonic decays of b-hadrons inside jets. The inclusive b-jet cross-section is measured as a function of transverse momentum in the range 20 < pT < 400 GeV and rapidity in the range |y| < 2.1. The bbbar-dijet cross-section is measured as a function of the dijet invariant mass in the range 110 < m_jj < 760 GeV, the azimuthal angle difference between the two jets and the angular variable chi in two dijet mass regions. The results are compared with next-to-leading-order QCD predictions. Good agreement is observed between the measured cross-sections and the predictions obtained using POWHEG + Pythia. MC@NLO + Herwig shows good agreement with the measured bbbar-dijet cross-section. However, it does not reproduce the measured inclusive cross-section well, particularly for central b-jets with large transverse momenta.Comment: 10 pages plus author list (21 pages total), 8 figures, 1 table, final version published in European Physical Journal

    Single hadron response measurement and calorimeter jet energy scale uncertainty with the ATLAS detector at the LHC

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    The uncertainty on the calorimeter energy response to jets of particles is derived for the ATLAS experiment at the Large Hadron Collider (LHC). First, the calorimeter response to single isolated charged hadrons is measured and compared to the Monte Carlo simulation using proton-proton collisions at centre-of-mass energies of sqrt(s) = 900 GeV and 7 TeV collected during 2009 and 2010. Then, using the decay of K_s and Lambda particles, the calorimeter response to specific types of particles (positively and negatively charged pions, protons, and anti-protons) is measured and compared to the Monte Carlo predictions. Finally, the jet energy scale uncertainty is determined by propagating the response uncertainty for single charged and neutral particles to jets. The response uncertainty is 2-5% for central isolated hadrons and 1-3% for the final calorimeter jet energy scale.Comment: 24 pages plus author list (36 pages total), 23 figures, 1 table, submitted to European Physical Journal

    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 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
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