2,036 research outputs found

    From prompt to direct J/ψ\psi production: new insights on the χc1\chi_{c1} and χc2\chi_{c2} polarizations and feed-down contributions from a global-fit analysis of mid-rapidity LHC data

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    While the prompt J/ψ\psi cross section and polarization have been measured with good precision as a function of transverse momentum, pTp_{\rm T}, those of the directly produced J/ψ\psi are practically unknown, given that the cross sections and polarizations of the χc1\chi_{c1} and χc2\chi_{c2} mesons, large indirect contributors to J/ψ\psi production, are only known with rather poor accuracy. The lack of precise measurements of the χcJ\chi_{cJ} polarizations induces large uncertainties in the level of their feed-down contributions to the prompt J/ψ\psi yield, because of the polarization-dependent acceptance corrections. The experimental panorama of charmonium production can be significantly improved through a consistent and model-independent global analysis of existing measurements of J/ψ\psi, ψ\psi(2S) and χc\chi_{c} cross sections and polarizations, faithfully respecting all the correlations and uncertainties. In particular, it is seen that the χcJ\chi_{cJ} polarizations and feed-down fractions to J/ψ\psi production have a negligible dependence on the J/ψ\psi pTp_{\rm T}, with average values λϑχc1=0.55±0.23\lambda_\vartheta^{\chi_{c1}} = 0.55 \pm 0.23, λϑχc2=0.39±0.22\lambda_\vartheta^{\chi_{c2}} = -0.39 \pm 0.22, Rχc1=(18.8±1.4)%R^{\chi_{c1}} = (18.8 \pm 1.4)\% and Rχc2=(6.5±0.5)%R^{\chi_{c2}} = (6.5 \pm 0.5)\%. The analysis also shows that (67.2±1.9)%(67.2 \pm 1.9)\% of the prompt J/ψ\psi yield is due to directly-produced mesons, of polarization constrained to remarkably small values, λϑJ/ψ=0.04±0.06\lambda_\vartheta^{{\rm J}/\psi} = 0.04 \pm 0.06.Comment: Submitted to Eur. Phys. J.

    The continuing evolution of Energy Policy

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    As the world confronts the Covid-19 pandemic, we hope that all of you are doing well. We know that many lives have been greatly disrupted, and that world economic activity is slowing and maybe declining in some places. We have read reports that energy consumption has been greatly affected by the slowdown in world economic activity—likely contributing to the sharp plunge in oil prices earlier this year. We do not know how long this pandemic may last. As we look forward to the end of the pandemic and a recovering world economy, however, we wonder if and how energy systems may have to be transformed, and whether new energy policy needs and approaches will emerge. Will we see any change in the trajectory of adopting sustainable energy systems and reducing carbon emissions?In the academic world, many of us are now teleworking and teaching our courses online. This transition has proved time consuming—so we want to thank our many reviewers who are staying on or close to schedule. So far, Energy Policy has been mostly unaffected by the pandemic, but we must recognize that the Elsevier employees who are responsible for the operations side of the journal may at some time be affected by Covid-19.In the meantime, we want to keep you informed about some recent developments regarding Energy Policy, including a little about its history and our editorial priorities

    The track finding algorithm of the Belle II vertex detectors

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    The Belle II experiment is a high energy multi purpose particle detector operated at the asymmetric e+e-- collier SuperKEKB in Tsukuba (Japan). In this work we describe the algorithm performing the pattern recognition for inner tracking detector which consists of two layers of pixel detectors and four layers of double sided silicon strip detectors arranged around the interaction region. The track finding algorithm will be used both during the High Level Trigger on-line track reconstruction and during the off-line full reconstruction. It must provide good efficiency down to momenta as low as 50 MeV/c where material effects are sizeable even in an extremely thin detector as the VXD. In addition it has to be able to cope with the high occupancy of the Belle II detectors due to the background. The underlying concept of the track finding algorithm, as well as details of the implementation are outlined. The algorithm is proven to run with good performance on simulated Y (4S) â\u86\u92 BB events with an efficiency for reconstructing tracks of above 90% over a wide range of momentum

    Which standard biomarkers are useful for the evaluation of myocardial injury after pulmonary vein isolation with cryoballoon?

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    Wstęp: W dotychczas opublikowanych badaniach dotyczących oceny uszkodzenia mięśnia sercowego po zabiegach ablacji oznaczano aktywność kinazy kreatynowej (CK), izoenzymu sercowego CK (CK-MB) i stężenie sercowych troponin I (cTnI) oraz T (cTnT). Dokonano pomiarów koncentracji kardio-specyficznych biomarkerów jako odpowiednika masy uszkodzonych komórek mięśnia sercowego. Cel: Celem pracy było wyjaśnienie, który ze standardowo dostępnych biomarkerów jest użyteczny w ocenie uszkodzenia komórek mięśnia sercowego po krio-balonowej izolacji żył płucnych (CBA). Metody: U 33 pacjentów z migotaniem przedsionków wykonano CBA. Próbki krwi pobrano przed CBA oraz w 1., 6. oraz 24. godzinie po CBA. Analizie poddano CK, CK-MB i cTnI. Wyniki: W próbkach pobranych po CBA zaobserwowano istotny wzrost koncentracji wszystkich badanych biomarkerów w stosunku do poziomu wyjściowego. Maksymalny wzrost zanotowano w 6. godzinie; CK, CK-MB i cTnI osiągnęły wartości patologiczne u, odpowiednio, 94%, 100% i 100% pacjentów. Maksymalne wartości CK i CK-MB korelowały (p < 0.05) z medianą temperatury osiągniętej w czasie CBA. Wnioski: Okazało się, że CK-MB jest najlepszym standardowym biomarkerem do oceny uszkodzenia mięśnia sercowego po CBA. Sercowa troponina I może być użyteczna jako dodatkowy parametr oceny uszkodzenia po CBA. Kardiol Pol 2011; 69, 11: 1151&#8211;1155Background: Many studies have used creatinine kinase (CK), myocardial bound for CK (CK-MB), and cardiac troponin I (cTnI) and T (cTnT) to evaluate myocardial cells injury after ablation. We applied measurements of the blood concentration of cardio-specific biomarkers as surrogates for the injured cell mass. Aim: To clarify which of the standard biomarkers are useful in the evaluation and quantification of lesions produced by cryoballoon ablation (CBA) during pulmonary vein isolation. Methods: The CBA was performed in 33 patients with atrial fibrillation. Blood samples were obtained before CBA and one, six, and 24 h after CBA. We analysed CK, CK-MB and cTnI. Results: A significant increase of all biomarkers was observed at each hour of collection as compared to the baseline measurement. Maximum median peak levels occurred at 6 h. Pathological values of CK, CK-MB and cTnI were observed in 94%, 100% and 100% of patients, respectively. Both maximum CK and CK-MB values correlated with median temperature (p < 0.05) reached during CBA. Additionally, CK-MB correlated with total cryo-time (p < 0.03). Conclusions: The CK-MB is the best biochemical marker for the evaluation of myocardial injury after CBA. The cTnI can be useful as an additional parameter of myocardial injury after CBA. Kardiol Pol 2011; 69, 11: 1151&#8211;115