Aluminum in corn plants: influence on growth and morpho-anatomy of root and leaf

A toxicidade do alumínio (Al) é um dos fatores mais limitantes para a produtividade. Esta pesquisa foi realizada para avaliar a influência do Al, em solução nutritiva, na altura de plantas, no peso da matéria seca e nas alterações morfoanatômicas de raízes e folhas de milho (Zea mays L.). O experimento foi conduzido em casa de vegetação com tratamentos constituídos de cinco doses de Al (0; 25; 75; 150; e 300 µmol L-1) e seis repetições. As soluções foram constantemente aeradas e o pH foi ajustado a 4,3, inicialmente. A matéria seca da parte aérea e das raízes e a altura das plantas diminuíram significativamente com o aumento da concentração de Al. As raízes de plantas de milho cultivadas em soluções com Al tiveram seu crescimento inibido e apresentaram menos raízes laterais e desenvolvimento do sistema radicular inferior, em comparação com as das plantas-controle. As folhas das plantas crescidas em soluções que continham 75 e 300 µmol L-1 de Al não apresentaram muita diferença anatômica em relação às das plantas-controle. A bainha da folha das plantas exposta ao Al apresentou epiderme uniestratificada revestida por uma fina camada de cutícula e as células da epiderme e do córtex foram as que menos se desenvolveram. No feixe vascular, o metaxilema e protoxilema não tinham paredes secundárias, e o diâmetro de ambos foi muito menor quando comparado com os das plantas-controle.

Search for neutral Higgs bosons decaying to tau pairs in p(p)over-bar collisions at root s=1.96 TeV

A search for the production of neutral Higgs bosons Phi decaying into tau(+)tau(-) final states in p (p) over bar collisions at a center-of-mass energy of 1.96 TeV is presented. The data, corresponding to an integrated luminosity of approximately 325 pb(-1), were collected by the D0 experiment at the Fermilab Tevatron Collider. Since no excess compared to the expectation from standard model processes is found, limits on the production cross section times branching ratio are set. The results are combined with those obtained from the D0 search for Phi b((b) over bar)-> b (b) over barb((b) over bar) and are interpreted in the minimal supersymmetric standard model.

Search for the Higgs boson in H -> WW(*) decays in p(p)over-bar collisions at root(s)=1.96 TeV

We present a search for the standard model Higgs boson in H -> WW(*) decays with e(+)e(-), e(+/-)mu(-/+), and mu(+)mu(-) final states in p (p) over bar collisions at a center-of-mass-energy of root s = 1.96 TeV. The data, collected from April 2002 to june 2004 with the D0 detector, correspond to an integrated luminosity of 300-325 pb(-1), depending on the final state. The number of events observed is consistent with the expectation from backgrounds. Limits from the combination of all three channels on the Higgs boson production cross section times branching ratio sigma x BR(H -> WW(*)) are presented.

Search for the standard model Higgs boson decaying to bottom quarks in pp collisions at root s=7 TeV

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Search for Higgs bosons decaying to tau(+)tau(-) pairs in p(p)over-bar collisions at root s=1.96 TeV

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Measurement of the ratio of the p(p)over-bar -> W + c-jet cross section to the inclusive p(p)over-bar -> W + jets cross section

We present a measurement of the fraction of inclusive W +jets events produced with net charm quantum number 11, denoted W + c-jet, in p collisions at root s = 1.96 TeV using approximately 1 fb(-1) of data collected by the do detector at the Fermilab Tevatron Collider. We identify the W +jets events via the leptonic W boson decays. Candidate W + c-jet events are selected by requiring a jet containing a muon in association with a reconstructed W boson and exploiting the charge correlation between this muon and W boson decay lepton to perform a nearly model-independent background subtraction. We measure the fraction of W + c-jet events in the inclusive W +jets sample for jet PT > 20 GeV and pseudorapidity |eta| < 2.5 to be 0.074 +/- 0.019(stat.) +/-(0.012)(0.014) (syst.), in agreement with theoretical predictions. The probability that background fluctuations could produce the observed fraction of W + c-jet events is estimated to be 2.5 x 10(-4), which corresponds to a 3.5 sigma statistical significance. Published by Elsevier B.V.

Measurement of isolated photon production in pp and PbPb collisions at root s(NN)=2.76 TeV

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Search for pair production of first-generation leptoquarks in p(p)over-bar collisions at root s=1.96 TeV

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

A combined search for the standard model Higgs boson at root S=1.96 TeV

We present new results of the search for WH --> lvb (b) over bar production in p (p) over bar collisions at a center-of-mass energy of root S = 1.96 TeV, based on a dataset with integrated luminosity of 0.44 fb(-1). We combine these new results with previously published searches by the do collaboration, for WH and ZH production analyzed in the E(T)b (b) over bar final state, for ZH (--> l(+)l(-)b (b) over bar) production, for WH (-->. WWW) production, and for H (--> W W) direct production. No signal-like excess is observed either in the W H analysis or in the combination of all D0 Higgs boson analyses. We set 95% C.L. (expected) upper limits on sigma(p (p) over bar --> WH) x B(H --> b (b) over bar) ranging from 1.6 (2.2) ph to 1.9 (3.3) pb for Higgs boson masses between 105 and 145 GeV, to be compared to the theoretical prediction of 0.13 pb for a Standard Model (SM) Higgs boson with mass in m(H) = 115 GeV. After combination with the other do Higgs boson searches, we obtain for in H = 115 GeV an observed (expected) limit 8.5 (12.1) times higher than the SM predicted Higgs boson production cross section. For m(H) = 160 GeV, the corresponding observed (expected) ratio is 10.2 (9.0). (C) 2008 Elsevier B.V. All rights reserved.

Search for neutral Higgs bosons in the multi-b-jet topology in 5.2 fb(-1) of p(p)over-bar collisions at root s=1.96 TeV

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Measurement of t(t)over-bar production in the tau plus jets topology using p(p)over-bar collisions root s=1.96 TeV

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Search for Associated W and Higgs Boson Production in p(p)over-bar Collisions at root s=1.96 TeV

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Measurement of the top quark pair production cross section in the lepton plus jets channel in proton-antiproton collisions at root s=1.96 TeV

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Indications of Suppression of Excited Upsilon States in Pb-Pb Collisions at root(NN)-N-s=2.76 TeV

A comparison of the relative yields of Upsilon resonances in the mu(+)mu(-) decay channel in Pb-Pb and pp collisions at a center-of-mass energy per nucleon pair of 2.76 TeV is performed with data collected with the CMS detector at the LHC. Using muons of transverse momentum above 4 GeV/c and pseudorapidity below 2.4, the double ratio of the Upsilon(2S) and Upsilon(3S) excited states to the Upsilon(1S) ground state in Pb-Pb and pp collisions, [Upsilon(2S + 3S)/Upsilon(1S)](Pb-Pb) /[Upsilon 2S + 3S)/Upsilon(1S)](pp), is found to be 0.31(-0.15)(+0.19) (stat_ +/- 0.03(syst). The probability to obtain the measured value, or lower, if the true double ratio is unity, is calculated to be less than 1%.

Search for Three-Jet Resonances in pp Collisions at root s=7 TeV

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)