Measurement of the tt¯ production cross-section using eμ events with b-tagged jets in pp collisions at √s=7 and 8 TeV with the ATLAS detector

The inclusive top quark pair (tt¯tt¯) production cross-section σtt¯σtt¯ has been measured in proton–proton collisions at s√=7 TeVs=7 TeV and s√=8 TeVs=8 TeV with the ATLAS experiment at the LHC, using tt¯tt¯ events with an opposite-charge eμeμ pair in the final state. The measurement was performed with the 2011 7 TeV dataset corresponding to an integrated luminosity of 4.6 fb−1fb−1 and the 2012 8 TeV dataset of 20.3 fb−1fb−1. The numbers of events with exactly one and exactly two bb-tagged jets were counted and used to simultaneously determine σtt¯σtt¯ and the efficiency to reconstruct and bb-tag a jet from a top quark decay, thereby minimising the associated systematic uncertainties. The cross-section was measured to be: σtt¯σtt¯=182.9±3.1±4.2±3.6±3.3 pb (s√=7 TeV)and=242.4±1.7±5.5±7.5±4.2 pb (s√=8 TeV), σtt¯=182.9±3.1±4.2±3.6±3.3 pb (s=7 TeV)andσtt¯=242.4±1.7±5.5±7.5±4.2 pb (s=8 TeV), where the four uncertainties arise from data statistics, experimental and theoretical systematic effects, knowledge of the integrated luminosity and of the LHC beam energy. The results are consistent with recent theoretical QCD calculations at next-to-next-to-leading order. Fiducial measurements corresponding to the experimental acceptance of the leptons are also reported, together with the ratio of cross-sections measured at the two centre-of-mass energies. The inclusive cross-section results were used to determine the top quark pole mass via the dependence of the theoretically predicted cross-section on mpoletmtpole giving a result of mpoletmtpole=172.9+2.5−2.6=172.9−2.6+2.5 GeV. By looking for an excess of tt¯tt¯ production with respect to the QCD prediction, the results were also used to place limits on the pair-production of supersymmetric top squarks t~1t~1 with masses close to the top quark mass, decaying via t~1→tχ~01t~1→tχ~10 to predominantly right-handed top quarks and a light neutralino χ~01χ~10, the lightest supersymmetric particle. Top squarks with masses between the top quark mass and 177 GeV are excluded at the 95 % confidence level

Internações pediátricas por condições sensíveis à atenção primária em Montes Claros, Minas Gerais, Brasil Admissions to pediatric hospital for conditions amenable to primary care in Montes Claros, Minas Gerais, Brazil

OBJETIVOS: avaliar a prevalência e os fatores associados às internações pediátricas por condições sensíveis à atenção primária (CSAP). MÉTODOS: realizouse inquérito hospitalar ao longo de um ano, com amostra representativa ealeatória de crianças internadas em um município do norte de Minas Gerais. Enfermarias pediátricas foram visitadas uma vez por semana em dias diferentes. Foram investigadas variáveis demográficas, socioeconômicas e relacionadas às condições de saúde. Para a definição das afecções sensíveis a atenção primária utilizou-se a relação oficial publicada pelo Ministério da Saúde. A regressão de Poisson foi utilizada para avaliação conjunta das variáveis associadas às internações por CSAP. RESULTADOS: foram entrevistadas 365 famílias e a prevalência de internações por CSAP foi de 41,4%(n=151). O modelo final revelou que, em uma análise conjunta, as variáveis se mantiveram estatisticamente associadas com as internações por CSAP foram: residir em área da Estratégia de Saúde da Família (RP=1,19; IC95%=1,03-1,61) e idade menor que dois anos de idade (RP=1,42; IC95%=1,35-1,51). CONCLUSÕES: a prevalência observada é semelhante à encontrada em outros estudos e salienta a necessidade de melhoria dos cuidados ambulatoriais para a faixa etária estudada.<br>OBJECTIVE: to evaluate the prevalence and factors associated with admission to pediatric hospital for conditions amenable to primary care. METHODS: an investigation was carried out for the duration of one year, with a representative sample of children admitted to hospital in a municipality in thenorth of the Brazilian State of Minas Gerais. Pediatric wards were visited once a week on different days. Demographic, socio-economic and health variables were studied. Conditions amenable to primary care were established using the official report published by the Brazilian Ministry of Health. The Poisson regression was used to evaluate the set of variables associated with admission to hospital for conditions amenable to primary care. RESULTS: 365 families were interviewed and the prevalence of admission to hospital for conditions amenable to primary care was 41.4% (n=151). Thefinal model revealed that, when taken together, the variables that continued to be associated in a statistically significant fashion with admissions to hospital for conditions amenable to primary care were: living in a Family Health Strategy area (PR=1.19;CI95%=1.039-1.61) and being aged under two years(PR=1.42; CI95%=1.35-1.51). CONCLUSION: the prevalence observed is similar to that found by other studies and highlights the need to improve out patient care for the age group covered by this study