39 research outputs found
Corrigendum to: “Measurement of the tt ̄ production cross-section using eμ events with b-tagged jets in pp collisions at √s = 13 TeV with the ATLAS detector” [Phys. Lett. B 761 (2016) 136–157]
This paper describes a measurement of the inclusive top quark pair production cross-section (sigma(t (t) over bar)) with a data sample of 3.2fb(-1)of proton-proton collisions at a centre-of-mass energy of root s= 13TeV, collected in 2015 by the ATLAS detector at the LHC. This measurement uses events with an opposite-charge electron-muon pair in the final state. Jets containing b-quarks are tagged using an algorithm based on track impact parameters and reconstructed secondary vertices. The numbers of events with exactly one and exactly two b-tagged jets are counted and used to determine simultaneously sigma(t (t) over bar) and the efficiency to reconstruct and b-tag a jet from a top quark decay, thereby minimising the associated systematic uncertainties. The cross-section is measured to be:sigma(t (t) over bar) = 818 +/- 8 (stat) +/- 27 (syst) +/- 19 (lumi) +/- 12 (beam) pb,where the four uncertainties arise from data statistics, experimental and theoretical systematic effects, the integrated luminosity and the LHC beam energy, giving a total relative uncertainty of 4.4%. The result is consistent with theoretical QCD calculations at next-to-next-to-leading order. A fiducial measurement corresponding to the experimental acceptance of the leptons is also presented
EXPERIMENTAL STUDY OF THE ORIENTATION OF THREE JET EVENTS IN e+ e- ANNIHILATION AT PETRA
The full TASSO data have been used to study the orientation of three-jet events ine+e− annihilation. The polar angle distributions of the normal to the three-jet plane as well as the polar angle distribution of the most energetic jet have been measured as a function of the thrust cut-off used to select the three-jet sample. The data corrected for radiation and detector effects are compared to QCD predictions and fair agreement is found. As a consistency check we also present measurements of the azimuthal correlations between the lepton and hadron planes. A significant azimuthal dependence is found, consistent again with the QCD predictions
Jaburetox, peptídeo derivado de ureases : efeitos sobre as vias enzimáticas da barata Nauphoeta cinerea
Jaburetox é um peptídeo recombinante (~11 kDa) derivado de uma das isoformas de ureases da planta Canavalia ensiformis, popularmente conhecida como feijão-de-porco. O peptídeo induz efeitos variados em diferentes ordens de insetos, incluindo interferência na contração muscular em baratas da espécie Nauphoeta cinerea, ativação do sistema imunitário do vetor da doença de Chagas, Rhodnius prolixus e também, modula a atividade da enzima UDP-N-acetilglicosamina pirofosforilase (UAP) e da óxido nítrico sintase (NOS) no sistema nervoso central de R. prolixus e Triatoma infestans. Além disso, quando injetado, o Jaburetox é letal para ninfas de R. prolixus e insetos adultos de T. infestans. No presente trabalho foi avaliado o efeito inseticida do Jaburetox em baratas adultas da espécie N. cinerea, assim como, exploramos os efeitos induzidos pelo peptídeo no sistema nervoso central, focando na atividade enzimática das enzimas UAP, NOS, fosfatases ácidas (ACP) e acetilcolinesterase (AChE). Os ensaios enzimáticos foram realizados após tratamentos in vivo e in vitro com o Jaburetox, utilizando homogenatos de sistema nervoso central. Técnicas espectrofotométricas foram utilizadas para mensurar a atividade enzimática e a expressão proteica foi avaliada através de Western blot. Para o ensaio inseticida, Jaburetox foi administrado via oral e via injeção no inseto, utilizando uma dose de 50 μg de Jaburetox por g de inseto, ou o mesmo volume de tampão como controle. Em N. cinerea, ambos os tratamentos, in vivo e in vitro, inibiram parcialmente a atividade da NOS, sem modificar os níveis proteicos da mesma. Nenhuma alteração foi observada nos níveis da ACP após tratamentos com Jaburetox. A enzima UAP apresentou diminuição da atividade após 18 h de tratamento in vivo com o Jaburetox. Além disso, em todos os tratamentos in vivo com o peptídeo foi observado um aumento da atividade da AChE, sugerindo um possível mecanismo de resposta aos inseticidas. Contudo, mesmo após injeção e ingestão de Jaburetox as baratas adultas não tiveram taxas de mortalidade significativas, indicando resistência ao efeito inseticida do peptídeo. Em suma nossos resultados sugerem que o Jaburetox afeta as vias nitrinérgica, assim com a atividade da UAP e da AChE na barata. O fato do peptídeo afetar diferentemente as atividades enzimáticas dos R. prolixus e da N. cinerea podem explicar o porquê as baratas não são susceptíveis ao Jaburetox.Jaburetox is a recombinant peptide (~11 kDa) derived from one of the Canavalia ensiformis (Jack bean) urease isoforms. The peptide induces several effects on insects of different orders, including the interference on muscle twitch tension in the cockroach Nauphoeta cinerea, the activation of the immune system in the Chagas’ disease vector Rhodnius prolixus, and the modulation of the enzyme activities of the UDP-N-acetylglucosamine pyrophosphorylase (UAP) and nitric oxide synthase (NOS) in the central nervous system of R. prolixus and the related triatomine Triatoma infestans. Moreover, when injected, the peptide is lethal for R. prolixus nymphs and T. infestans adults. Here, we evaluated the insecticidal effect of Jaburetox on N. cinerea adult cockroaches and explored the effects induced by Jaburetox on the central nervous system, focusing on the enzymatic activities of UAP, NOS, acid phosphatases (ACP), and acetylcholinesterase (AChE). The enzymatic experiments were performed after in vitro and in vivo treatments with Jaburetox using central nervous system homogenates from adult cockroaches. Spectrophotometric assays were employed to measure the enzyme activities and the protein expression of UAP and NOS was evaluated by Western blot. The insecticidal assay was conducted by injection and ingestion of 50 μg of Jaburetox per g of insect or the same volume of buffer for the controls. In N. cinerea, both in vivo and in vitro treatments with the peptide partially inhibited the activity of NOS, without modifying the protein levels. No alterations on ACP activity were observed upon Jaburetox treatment. In addition, the enzyme activity of UAP only had its activity affected at 18 h after injection. The peptide increased the AChE activity, suggesting a possible mechanism involved in overcoming the toxic effects of the insecticide. Moreover, the cockroaches did not die after Jaburetox injection and ingestion, indicating resistance to the toxic action of the peptide. Taken together, our findings indicate that Jaburetox alters the nitrinergic signaling as well as the AChE and UAP activities. The fact that Jaburetox affects differently the enzyme activities in R. prolixus and N. cinerea may explain why the cockroach is not susceptible to the lethal effect of the peptide
Experimental study of the orientation of three-jet events in annihilation at PETRA
The full TASSO data have been used to study the orientation of three-jet events ine+e− annihilation. The polar angle distributions of the normal to the three-jet plane as well as the polar angle distribution of the most energetic jet have been measured as a function of the thrust cut-off used to select the three-jet sample. The data corrected for radiation and detector effects are compared to QCD predictions and fair agreement is found. As a consistency check we also present measurements of the azimuthal correlations between the lepton and hadron planes. A significant azimuthal dependence is found, consistent again with the QCD predictions