99 research outputs found

    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

    Measurement of the cross-section for b-jets produced in association with a Z boson at root s=7 TeV with the ATLAS detector ATLAS Collaboration

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    A measurement is presented of the inclusive cross-section for b-jet production in association with a Z boson in pp collisions at a centre-of-mass energy of root s = 7 TeV. The analysis uses the data sample collected by the ATLAS experiment in 2010, corresponding to an integrated luminosity of approximately 36 pb(-1). The event selection requires a Z boson decaying into high P-T electrons or muons, and at least one b-jet, identified by its displaced vertex, with transverse momentum p(T) > 25 GeV and rapidity vertical bar y vertical bar < 2.1. After subtraction of background processes, the yield is extracted from the vertex mass distribution of the candidate b-jets. The ratio of this cross-section to the inclusive Z cross-section (the average number of b-jets per Z event) is also measured. Both results are found to be in good agreement with perturbative QCD predictions at next-to-leading order

    Obesity and normal birth: A qualitative study of clinician’s management of obese pregnant women during labour

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    Background: Currently one-fifth of women in the UK are obese. Obese, pregnant woman are at an increased risk of experiencing complications of labour and serious morbidity. However, they are also more likely to undergo medical interventions such as induction of labour and caesarean section which in themselves confer additional health risks for obese women such as wound infection and deep vein thrombosis. Reducing unnecessary interventions and increasing normal birth rates for obese women would substantially improve their postnatal health and wellbeing and reduce the burden of NHS resources required to care for them post operatively. This research aimed to explore practitioners&rsquo; experiences of and strategies for providing intrapartum care to obese women.&nbsp; Method: A qualitative methodology was adopted, focus groups and individual interviews were conducted with health professionals. Audio recordings were transcribed verbatim and data analysed using a framework approach.&nbsp; Results: Twenty-four health professionals participated; Six Consultant Obstetricians two Consultant Anaesthetists and 16 midwives. Three key themes emerged from the data: medicalisation of obese birth; promotion of normal obese birth; and the complexities and contradictions in staff attitudes and behaviours. The overall interpretation is that positive approaches to obese birth offer opportunities to promote normal birth. However, many health professionals find the provision of intrapartum care to obese women challenging, and attitudes and behaviours towards the promotion of normal birth are heterogeneous, complex and contradictory.&nbsp; Conclusion: The care of obese women during labour is generally medicalised and focussed on the associated risks. However, although there are conflicting views on how to care for obese women, some practitioners do strive to promote normality and optimise the potential for normal birth by challenging current practices and utilise some &lsquo;interventions&rsquo; in order to facilitate normality and mobility during childbirth. Obesity is a major and growing health problem and a major cause of morbidity and mortality for pregnant women. It is essential that more positive proactive guidelines are available to maximise normal birth if the postnatal health of obese women is to be improved

    Changes to the Fossil Record of Insects through Fifteen Years of Discovery

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    The first and last occurrences of hexapod families in the fossil record are compiled from publications up to end-2009. The major features of these data are compared with those of previous datasets (1993 and 1994). About a third of families (>400) are new to the fossil record since 1994, over half of the earlier, existing families have experienced changes in their known stratigraphic range and only about ten percent have unchanged ranges. Despite these significant additions to knowledge, the broad pattern of described richness through time remains similar, with described richness increasing steadily through geological history and a shift in dominant taxa, from Palaeoptera and Polyneoptera to Paraneoptera and Holometabola, after the Palaeozoic. However, after detrending, described richness is not well correlated with the earlier datasets, indicating significant changes in shorter-term patterns. There is reduced Palaeozoic richness, peaking at a different time, and a less pronounced Permian decline. A pronounced Triassic peak and decline is shown, and the plateau from the mid Early Cretaceous to the end of the period remains, albeit at substantially higher richness compared to earlier datasets. Origination and extinction rates are broadly similar to before, with a broad decline in both through time but episodic peaks, including end-Permian turnover. Origination more consistently exceeds extinction compared to previous datasets and exceptions are mainly in the Palaeozoic. These changes suggest that some inferences about causal mechanisms in insect macroevolution are likely to differ as well

    Review of Journal of Cardiovascular Magnetic Resonance 2013

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    Characterisation of polyphenols in Terminalia arjuna bark extract

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    The bark of Terminalia arjuna is known for its heart-health benefits in ayurvedic literature. This has been further supported by in vivo studies on animal and human volunteers. But there is no detailed study on identification of the active ingredients such as polyphenols. Polyphenols possesses antioxidant properties and are well-known health actives, it is important to characterise polyphenols in Terminalia arjuna. Aqueous extract of Terminalia arjuna bark was analysed for its composition and molecular weight distribution by dialysis. Compositional analysis revealed that it has 44% polyphenols and dialysis study showed that 70% of the polyphenols have molecular weight greater than 3.5 kDa. High performance liquid chromatography and liquid chromatography-mass spectrometry analysis of Terminalia arjuna, confirmed that it contains flavon-3-ols such as (+)-catechin, (+)-gallocatechin and (−)-epigallocatechin. Phenolic acids such as gallic acid, ellagic acid and its derivatives were also found in Terminalia arjuna extract. Ellagic acid derivatives were isolated and their spectral studies indicated that isolated compounds were 3-O-methyl-ellagic acid 4- O-ÎČ-D-xylopyranoside, ellagic acid and 3-O-methyl ellagic acid 3-O-rhamnoside. Hydrolysis and thiolysis studies of high molecular weight polyphenols indicated that they are proanthocyanidins. Given these results, it may be possible to attribute the heart-health effects of Terminalia arjuna to these polyphenols which may be responsible for the endothelial benefit functions like tea

    Compound effect of EHD and surface roughness in pool boiling and CHF with R-123

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    This article is a post-print version of the fianl published article which may be accessed at the link below.Saturated pool boiling of R-123 at 1 bar, including the critical heat flux (CHF), was enhanced by modifying the surface characteristics and applying a high intensity electrostatic field, the latter termed electrohydrodynamic (and abbreviated EHD) enhancement. The heat flux was varied from very low values in the natural convection regime up to CHF. Experiments were performed with increasing and decreasing heat flux to study boiling hysteresis without and with EHD. Boiling occurred on the sand blasted surface of a cylindrical copper block with embedded electrical heating elements, with standardized surface parameter Pa = 3.5 ÎŒm. The electric field was generated by a potential of 5 kV to 25 kV, applied through a 40 mm diameter circular electrode of ss-304 wire mesh, aperture size 5.1 mm, located at distances of 5 - 60 mm from the surface, with most of the data obtained for 20 mm. The data for the rough surface were compared with earlier data for a smooth surface and indicated a significant increase in the heat transfer rates. EHD produced a further increase in the heat transfer rates, particularly at low heat flux values and near the CHF. Boiling hysteresis was reduced progressively by EHD and eliminated at high field strength.This work was supported by Government of Pakistan under a scholarship programme

    Conhecimento de fisioterapeutas sobre a atuação em suporte båsico de vida Physical therapists' knowledge on basic life support

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    O estudo visou avaliar o conhecimento de fisioterapeutas e graduandos em Fisioterapia sobre diagnĂłstico e atendimento de urgĂȘncia Ă  parada cardiorrespiratĂłria. A amostra foi composta de 72 estudantes e 108 fisioterapeutas, dos quais 64 atuam no ambiente extra-hospitalar e 44 no ambiente hospitalar. Foi aplicado aos participantes um questionĂĄrio sobre ressuscitação cardiopulmonar (RCP) baseado nas diretrizes da American Heart Association de 2005. As respostas foram analisadas estatisticamente. Quanto ao diagnĂłstico da parada cardĂ­aca, os grupos comportaram-se de maneira semelhante, optando pela avaliação da"presença de pulso e respiração". Quanto Ă  seqĂŒĂȘncia de atendimento da RCP, a seqĂŒĂȘncia preconizada foi corretamente indicada por 52,8% do grupo estudante, 65,9% do subgrupo hospitalar e 40,6% do subgrupo extra-hospitalar. Quanto Ă  relação compressĂŁo/ventilação, apenas 4,1% do grupo estudante, ninguĂ©m do extra-hospitalar e 25% do subgrupo hospitalar indicaram a relação preconizada atualmente. Quase todos (94%) os participantes reconheceram a importĂąncia do conhecimento em RCP para o fisioterapeuta. Assim, a maioria dos atuais e futuros fisioterapeutas reconhecem a importĂąncia da RCP para sua atuação profissional, mas tĂȘm conhecimento insuficiente sobre o tema e apenas uma pequena parcela busca atualizar-se.<br>This study aimed at assessing undergraduates' and physical therapists' knowledge on diagnosing and emergency treating cardiopulmonary arrest. Subjects were 72 students and 108 physical therapists - of which 64 were active in non-hospital environment and 44 in hospitals - who answered a questionnaire on cardiopulmonary resuscitation (CPR) based on the American Heart Association 2005 guidelines. Answers were statistically analysed. As to diagnosing cardiopulmonary arrest, groups behaved similarly, having chosen the option"absence of consciousness, pulse and breath". Concerning the pattern of CPR assistance, the recommended ABCD sequence was recognized by 52.8% of the students, 65.9% of the hospital subgroup, and 40.6% of the non-hospital subgroup; nobody of the latter, only 4.1% of the students, and 25% of hospital professionals indicated the currently recommended compression/ventilation ratio. Almost all (94%) participants acknowledged the importance of CPR knowledge in physical therapy practice. Thus, though most current and future physical therapists recognize the importance of CPR for their professional role, they have insufficient knowledge about the subject and only few of them seek to update their knowledge
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