58 research outputs found
International variation in evidence-based emergency department management of bronchiolitis: a retrospective cohort study
Objectives: We aimed to evaluate the international variation in the use of evidence-based management (EBM) in bronchiolitis. We hypothesised that management consistent with full-EBM practices is associated with the research network of care, adjusted for patient-level characteristics. Secondary objectives were to determine the association between full-EBM and (1) hospitalisation and (2) emergency department (ED) revisits resulting in hospitalisation within 21 days. Design: A secondary analysis of a retrospective cohort study. Setting: 38 paediatric EDs belonging to the Paediatric Emergency Research Network in Canada, USA, Australia/New Zealand UK/Ireland and Spain/Portugal. Patients: Otherwise healthy infants 2â11 months old diagnosed with bronchiolitis between 1 January 2013 and 31 December, 2013. Outcome measures: Primary outcome was management consistent with full-EBM, that is, no bronchodilators/corticosteroids/antibiotics, no chest radiography or laboratory testing. Secondary outcomes included hospitalisations during the index and subsequent ED visits. Results: 1137/2356 (48.3%) infants received full-EBM (ranging from 13.2% in Spain/Portugal to 72.3% in UK/Ireland). Compared with the UK/Ireland, the adjusted ORs (aOR) of full-EBM receipt were lower in Spain/Portugal (aOR 0.08, 95% CI 0.02 to 0.29), Canada (aOR 0.13 (95% CI 0.06 to 0.31) and USA (aOR 0.16 (95% CI 0.07 to 0.35). EBM was less likely in infants with dehydration (aOR 0.49 (95% CI 0.33 to 0.71)), chest retractions (aOR 0.69 (95% CI 0.52 to 0.91)) and nasal flaring (aOR 0.69 (95% CI 0.52 to 0.92)). EBM was associated with reduced odds of hospitalisation at the index visit (aOR 0.77 (95% CI 0.60 to 0.98)) but not at revisits (aOR 1.17 (95% CI 0.74 to 1.85)). Conclusions: Infants with bronchiolitis frequently do not receive full-EBM ED management, particularly those outside of the UK/Ireland. Furthermore, there is marked variation in full-EBM between paediatric emergency networks, and full-EBM delivery is associated with lower likelihood of hospitalisation. Given the global bronchiolitis burden, international ED-focused deimplementation of non-indicated interventions to enhance EBM is needed
Observation of the B0 â Ï0Ï0 decay from an amplitude analysis of B0 â (Ï+Ïâ)(Ï+Ïâ) decays
Protonâproton collision data recorded in 2011 and 2012 by the LHCb experiment, corresponding to an integrated luminosity of 3.0 fbâ1 , are analysed to search for the charmless B0âÏ0Ï0 decay. More than 600 B0â(Ï+Ïâ)(Ï+Ïâ) signal decays are selected and used to perform an amplitude analysis, under the assumption of no CP violation in the decay, from which the B0âÏ0Ï0 decay is observed for the first time with 7.1 standard deviations significance. The fraction of B0âÏ0Ï0 decays yielding a longitudinally polarised final state is measured to be fL=0.745â0.058+0.048(stat)±0.034(syst) . The B0âÏ0Ï0 branching fraction, using the B0âÏKâ(892)0 decay as reference, is also reported as B(B0âÏ0Ï0)=(0.94±0.17(stat)±0.09(syst)±0.06(BF))Ă10â6
Angular analysis of the B-0 -> K*(0) e(+) e(-) decay in the low-q(2) region
An angular analysis of the decay is performed using a data sample, corresponding to an integrated luminosity of 3.0 {\mbox{fb}^{-1}}, collected by the LHCb experiment in collisions at centre-of-mass energies of 7 and 8 TeV during 2011 and 2012. For the first time several observables are measured in the dielectron mass squared () interval between 0.002 and 1.120. The angular observables and which are related to the polarisation and to the lepton forward-backward asymmetry, are measured to be and , where the first uncertainty is statistical and the second systematic. The angular observables and which are sensitive to the photon polarisation in this range, are found to be and . The results are consistent with Standard Model predictions.An angular analysis of the B â K^{*}^{0} e e decay is performed using a data sample, corresponding to an integrated luminosity of 3.0 fb, collected by the LHCb experiment in pp collisions at centre-of-mass energies of 7 and 8 TeV during 2011 and 2012. For the first time several observables are measured in the dielectron mass squared (q) interval between 0.002 and 1.120 GeV /c. The angular observables F and A which are related to the K^{*}^{0} polarisation and to the lepton forward-backward asymmetry, are measured to be F = 0.16 ± 0.06 ± 0.03 and A â=â0.10â±â0.18â±â0.05, where the first uncertainty is statistical and the second systematic. The angular observables A and A which are sensitive to the photon polarisation in this q range, are found to be A â=âââ0.23â±â0.23â±â0.05 and A â=â0.14â±â0.22â±â0.05. The results are consistent with Standard Model predictions.An angular analysis of the decay is performed using a data sample, corresponding to an integrated luminosity of 3.0 {\mbox{fb}^{-1}}, collected by the LHCb experiment in collisions at centre-of-mass energies of 7 and 8 TeV during 2011 and 2012. For the first time several observables are measured in the dielectron mass squared () interval between 0.002 and 1.120. The angular observables and which are related to the polarisation and to the lepton forward-backward asymmetry, are measured to be and , where the first uncertainty is statistical and the second systematic. The angular observables and which are sensitive to the photon polarisation in this range, are found to be and . The results are consistent with Standard Model predictions
Study of the rare B-s(0) and B-0 decays into the pi(+) pi(-) mu(+) mu(-) final state
A search for the rare decays and is performed in a data set corresponding to an integrated luminosity of 3.0 fb collected by the LHCb detector in proton-proton collisions at centre-of-mass energies of 7 and 8 TeV. Decay candidates with pion pairs that have invariant mass in the range 0.5-1.3 GeV/ and with muon pairs that do not originate from a resonance are considered. The first observation of the decay and the first evidence of the decay are obtained and the branching fractions are measured to be and , where the third uncertainty is due to the branching fraction of the decay , used as a normalisation.A search for the rare decays Bs0âÏ+ÏâÎŒ+ÎŒâ and B0âÏ+ÏâÎŒ+ÎŒâ is performed in a data set corresponding to an integrated luminosity of 3.0 fbâ1 collected by the LHCb detector in protonâproton collisions at centre-of-mass energies of 7 and 8 TeV . Decay candidates with pion pairs that have invariant mass in the range 0.5â1.3 GeV/c2 and with muon pairs that do not originate from a resonance are considered. The first observation of the decay Bs0âÏ+ÏâÎŒ+ÎŒâ and the first evidence of the decay B0âÏ+ÏâÎŒ+ÎŒâ are obtained and the branching fractions, restricted to the dipion-mass range considered, are measured to be B(Bs0âÏ+ÏâÎŒ+ÎŒâ)=(8.6±1.5 (stat)±0.7 (syst)±0.7(norm))Ă10â8 and B(B0âÏ+ÏâÎŒ+ÎŒâ)=(2.11±0.51(stat)±0.15(syst)±0.16(norm))Ă10â8 , where the third uncertainty is due to the branching fraction of the decay B0âJ/Ï(âÎŒ+ÎŒâ)Kâ(892)0(âK+Ïâ) , used as a normalisation.A search for the rare decays Bs0âÏ+ÏâÎŒ+ÎŒâ and B0âÏ+ÏâÎŒ+ÎŒâ is performed in a data set corresponding to an integrated luminosity of 3.0 fbâ1 collected by the LHCb detector in protonâproton collisions at centre-of-mass energies of 7 and 8 TeV . Decay candidates with pion pairs that have invariant mass in the range 0.5â1.3 GeV/c2 and with muon pairs that do not originate from a resonance are considered. The first observation of the decay Bs0âÏ+ÏâÎŒ+ÎŒâ and the first evidence of the decay B0âÏ+ÏâÎŒ+ÎŒâ are obtained and the branching fractions, restricted to the dipion-mass range considered, are measured to be B(Bs0âÏ+ÏâÎŒ+ÎŒâ)=(8.6±1.5 (stat)±0.7 (syst)±0.7(norm))Ă10â8 and B(B0âÏ+ÏâÎŒ+ÎŒâ)=(2.11±0.51(stat)±0.15(syst)±0.16(norm))Ă10â8 , where the third uncertainty is due to the branching fraction of the decay B0âJ/Ï(âÎŒ+ÎŒâ)Kâ(892)0(âK+Ïâ) , used as a normalisation.A search for the rare decays and is performed in a data set corresponding to an integrated luminosity of 3.0 fb collected by the LHCb detector in proton-proton collisions at centre-of-mass energies of 7 and 8 TeV. Decay candidates with pion pairs that have invariant mass in the range 0.5-1.3 GeV/ and with muon pairs that do not originate from a resonance are considered. The first observation of the decay and the first evidence of the decay are obtained and the branching fractions, restricted to the dipion-mass range considered, are measured to be and , where the third uncertainty is due to the branching fraction of the decay , used as a normalisation
Measurement of the Z plus b-jet cross-section in pp collisions at root s=7 TeV in the forward region
The associated production of a Z boson or an off-shell photon with a bottom quark in the forward region is studied using proton-proton collisions at a centre-of-mass energy of . The Z bosons are reconstructed in the final state from muons with a transverse momentum larger than , while two transverse momentum thresholds are considered for jets ( and ). Both muons and jets are reconstructed in the pseudorapidity range , and \sigma(\text{\text{Z}/\gamma^*(\mu^{+}\mu^{-})+b-jet}) = 167 \pm 47 (\text{stat}) \pm 29 (\text{syst}) \pm 6 (\text{lumi}) {\,{fb}} for {p_{\rm T}}(jet)
Search for the lepton flavour violating decay tau(-) -> mu(-)mu(+)mu(-)
A search for the lepton flavour violating decay is performed with the LHCb experiment. The data sample corresponds to an integrated luminosity of 1.0 fb of proton-proton collisions at a centre-of-mass energy of 7 TeV and 2.0 fb at 8 TeV. No evidence is found for a signal, and a limit is set at 90% confidence level on the branching fraction, .A search for the lepton flavour violating decay Ï â ÎŒ ÎŒ ÎŒ is performed with the LHCb experiment. The data sample corresponds to an integrated luminosity of 1.0 fb of proton-proton collisions at a centre-of-mass energy of 7 TeV and 2.0 fb at 8 TeV. No evidence is found for a signal, and a limit is set at 90% confidence level on the branching fraction, .A search for the lepton flavour violating decay is performed with the LHCb experiment. The data sample corresponds to an integrated luminosity of of proton-proton collisions at a centre-of-mass energy of and at . No evidence is found for a signal, and a limit is set at confidence level on the branching fraction,
Precise measurements of the properties of the B-1(5721)(0,+) and B-2*(5747)(0,+) states and observation of B-+,B-0 pi(-,+) mass structures
Invariant mass distributions of and combinations are investigated in order to study excited B mesons. The analysis is based on a data sample corresponding to of collision data, recorded by the LHCb detector at centre-of-mass energies of 7 and 8 TeV. Precise measurements of the masses and widths of the and states are reported. Clear enhancements, particularly prominent at high pion transverse momentum, are seen over background in the mass range - MeV in both and combinations. The structures are consistent with the presence of four excited B mesons, labelled and , whose masses and widths are obtained under different hypotheses for their quantum numbers.Invariant mass distributions of B Ï and B Ï combinations are investigated in order to study excited B mesons. The analysis is based on a data sample corresponding to 3.0 fb of pp collision data, recorded by the LHCb detector at centre-of-mass energies of 7 and 8 TeV. Precise measurements of the masses and widths of the B(5721) and B(5747) states are reported. Clear enhancements, particularly prominent at high pion transverse momentum, are seen over background in the mass range 5850-6000 MeV in both B Ï and B Ï combinations. The structures are consistent with the presence of four excited B mesons, labelled B (5840) and B (5960), whose masses and widths are obtained under different hypotheses for their quantum numbers.Invariant mass distributions of B+pi- and B0pi+ combinations are investigated in order to study excited B mesons. The analysis is based on a data sample corresponding to 3.0 fb-1 of pp collision data, recorded by the LHCb detector at centre-of-mass energies of 7 and 8 TeV. Precise measurements of the masses and widths of the B_1(5721)^(0,+) and B_2*(5747)^(0,+) states are reported. Clear enhancements, particularly prominent at high pion transverse momentum, are seen over background in the mass range 5850--6000 MeV in both B+pi- and B0pi+ combinations. The structures are consistent with the presence of four excited B mesons, labelled B_J(5840)^(0,+) and B_J(5960)^(0,+), whose masses and widths are obtained under different hypotheses for their quantum numbers
Measurement of the lifetime of the meson using the decay mode
The difference in total widths between the and mesons is measured using 3.0fb of data collected by the LHCb experiment in 7 and 8 TeV centre-of-mass energy proton-proton collisions at the LHC. Through the study of the time evolution of and decays, the width difference is measured to be where the first uncertainty is statistical and the second systematic. The known lifetime of the meson is used to convert this to a precise measurement of the lifetime, where the first uncertainty is statistical and the second systematic.The difference in total widths between the B+ c and B+ mesons is measured using 3.0 fbâ1 of data collected by the LHCb experiment in 7 and 8 TeV centre-of-mass energy proton-proton collisions at the LHC. Through the study of the time evolution of B+ c â J/ÏÏ+ and B+ â J/ÏK+ decays, the width difference is measured to be âΠ⥠ÎB + c â ÎB+ = 4.46 ± 0.14 ± 0.07 mmâ1 c, where the first uncertainty is statistical and the second systematic. The known lifetime of the B+ meson is used to convert this to a precise measurement of the B+ c lifetime, ÏB + c = 513.4 ± 11.0 ± 5.7 fs, where the first uncertainty is statistical and the second systematic.The difference in total widths between the Bc+ and B+ mesons is measured using a data sample corresponding to an integrated luminosity of 3.0 fbâ1 collected by the LHCb experiment in 7 and 8 TeV centre-of-mass energy protonâproton collisions at the LHC. Through the study of the time evolution of Bc+âJ/ÏÏ+ and B+âJ/ÏK+ decays, the width difference is measured to be ÎÎâĄÎBc+âÎB+=4.46±0.14±0.07 mmâ1c, where the first uncertainty is statistical and the second systematic. The known lifetime of the B+ meson is used to convert this to a precise measurement of the Bc+ lifetime, ÏBc+=513.4±11.0±5.7 fs, where the first uncertainty is statistical and the second is systematic.The difference in total widths between the Bc+ and B+ mesons is measured using a data sample corresponding to an integrated luminosity of 3.0 fbâ1 collected by the LHCb experiment in 7 and 8 TeV centre-of-mass energy protonâproton collisions at the LHC. Through the study of the time evolution of Bc+âJ/ÏÏ+ and B+âJ/ÏK+ decays, the width difference is measured to be ÎÎâĄÎBc+âÎB+=4.46±0.14±0.07 mmâ1c, where the first uncertainty is statistical and the second systematic. The known lifetime of the B+ meson is used to convert this to a precise measurement of the Bc+ lifetime, ÏBc+=513.4±11.0±5.7 fs, where the first uncertainty is statistical and the second is systematic
Measurement of asymmetries and polarisation fractions in decays
An angular analysis of the decay is performed using collisions corresponding to an integrated luminosity of collected by the LHCb experiment at a centre-of-mass energy TeV. A combined angular and mass analysis separates six helicity amplitudes and allows the measurement of the longitudinal polarisation fraction for the decay. A large scalar contribution from the and resonances is found, allowing the determination of additional asymmetries. Triple product and direct asymmetries are determined to be compatible with the Standard Model expectations. The branching fraction is measured to be
Measurement of the CP-violating phase in decays and limits on penguin effects
Time-dependent CP violation is measured in the channel for each resonant final state using data collected with an integrated luminosity of 3.0 fb in collisions using the LHCb detector. The final state with the largest rate, , is used to measure the CP-violating angle to be . This result can be used to limit the size of penguin amplitude contributions to CP violation measurements in, for example, decays. Assuming approximate SU(3) flavour symmetry and neglecting higher order diagrams, the shift in the CP-violating phase is limited to be within the interval [, +] at 95% confidence level. Changes to the limit due to SU(3) symmetry breaking effects are also discussed.Time-dependent CP violation is measured in the B(âââ)0âJ/ÏÏ+Ïâ channel for each Ï+Ïâ resonant final state using data collected with an integrated luminosity of 3.0 fb â1 in pp collisions using the LHCb detector. The final state with the largest rate, J/ÏÏ0(770) , is used to measure the CP -violating angle 2ÎČeff to be (41.7±9.6â6.3+2.8)° . This result can be used to limit the size of penguin amplitude contributions to CP violation measurements in, for example, B(âââ)s0âJ/ÏÏ decays. Assuming approximate SU(3) flavour symmetry and neglecting higher order diagrams, the shift in the CP -violating phase Ïs is limited to be within the interval [ â1.05°,+1.18° ] at 95% confidence level. Changes to the limit due to SU(3) symmetry breaking effects are also discussed.Time-dependent CP violation is measured in the channel for each resonant final state using data collected with an integrated luminosity of 3.0 fb in collisions using the LHCb detector. The final state with the largest rate, , is used to measure the CP-violating angle to be . This result can be used to limit the size of penguin amplitude contributions to CP violation measurements in, for example, decays. Assuming approximate SU(3) flavour symmetry and neglecting higher order diagrams, the shift in the CP-violating phase is limited to be within the interval [, +] at 95% confidence level. Changes to the limit due to SU(3) symmetry breaking effects are also discussed.Time-dependent CP violation is measured in the B0âJ/ÏÏ+Ïâ channel for each Ï+Ïâ resonant final state using data collected with an integrated luminosity of 3.0 fb â1 in pp collisions using the LHCb detector. The final state with the largest rate, J/ÏÏ0(770) , is used to measure the CP -violating angle 2ÎČeff to be (41.7±9.6â6.3+2.8)° . This result can be used to limit the size of penguin amplitude contributions to CP violation measurements in, for example, Bs0âJ/ÏÏ decays. Assuming approximate SU(3) flavour symmetry and neglecting higher order diagrams, the shift in the CP -violating phase Ïs is limited to be within the interval [ â1.05°,+1.18° ] at 95% confidence level. Changes to the limit due to SU(3) symmetry breaking effects are also discussed
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