40 research outputs found

    Forecast of urban air pollution level by expertise

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    Introduction. A climate pattern with marine features is typical for St. Petersburg. Vagaries of weather and climate conditions in the last decade specify the timeliness of this work, the purpose of which is to outline the expected level of the open air pollution in St. Petersburg by the “decision tree” method. Materials and Methods. Current data of weather observations carried out at station 26063 (St. Petersburg) from 2006 to 2014 are studied and processed. Within the framework of the study, the data were considered on the vertical profile of the atmosphere obtained through radiosounding the atmosphere of St. Petersburg at 00.00 and 12.00 UTC (Universal Time Coordinated) at Voeykovo station. Research Results . In the course of the investigation, the dependence of the atmospheric air pollution level on the synoptic process and the inertial factor was established which made it possible to figure a scheme for forecasting the air pollution level in the form of the decision tree by expertise. Accuracy of the predictive determination of the expected air pollution group in St. Petersburg was calculated on the dependent material and topped 90% (nighttime hours) and 91% (daytime hours) for a cold period; and - 84% (nighttime hours) and 87% (daylight hours) for a warm period of the year. This suggests that the proposed schemes allow obtaining a more efficient prediction of the atmospheric air pollution level in a cold period of the year. Discussion and Conclusions . In conclusion, basic outcomes and inferences are summarized. - Archives of baseline standard meteorological data and data of the atmosphere radiosounding, as well as synoptic situations and information on the level of atmospheric air pollution in St. Petersburg for the period from 2006 to 2014, are formed. - Groups of synoptic processes typical for St. Petersburg from 2006 to 2014 are established. - Schemes for forecasting the atmospheric air pollution level are developed using the “decision tree” method with accuracy of 84-91%. The research results are applicable for forecasting the urban air pollution level

    Regioselective CH Bond Activation on Stabilized Nitrogen Ylides Promoted by Pd(II) Complexes: Scope and Limitations

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    The orthopalladation of N-ylides [HxCyN–CHC(O)Ar] (HxCyN = pyridine, benzylamine, imidazole, aniline, and phenylpyridine; Ar = aryl) has been studied. The incorporation of the Pd atom to these substrates is regioselective, since the orthopalladation is produced, in most of the cases, only at the aryl ring of the benzoyl group with concomitant C-bonding of the N-ylide. The X-ray structure of one representative example is reported. Factors governing the observed orientation are discussed, because this regioselectivity is worthy of note, considering the deactivating nature of the carbonyl group. Two exceptions to the general trend have been observed. The first one is the double metalation of the ylide [PhMe2NCHC(O)Ph], which incorporates one Pd at each Ph. The second one is the palladation of the phenylpyridine derivative, which occurs at the pyridinic 2-phenyl ring and produces a six-membered palladacycle.Funding by the Ministerio de Ciencia e Innovacion (MICINN) (Spain, Project CTQ2008-01784) and Gobierno de Aragon (Grupo E97) is gratefully acknowledged. L.C. thanks Consejo Superior de Investigaciones Cientificas and MICINN for a Juan de la Cierva contract.Peer reviewe

    Proceedings Of The 23Rd Paediatric Rheumatology European Society Congress: Part Two

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    Multiplicity dependence of inclusive J/ψ production at midrapidity in pp collisions at √s=13 TeV

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    Measurements of the inclusive J/ψ yield as a function of charged-particle pseudorapidity density dNch/dη in pp collisions at √s = 13 TeV with ALICE at the LHC are reported. The J/ψ meson yield is measured at midrapidity (|y| < 0.9) in the dielectron channel, for events selected based on the charged-particle multiplicity at midrapidity (|η| < 1) and at forward rapidity (−3.7 < η < −1.7 and 2.8 < η < 5.1); both observables are normalized to their corresponding averages in minimum bias events. The increase of the normalized J/ψ yield with normalized dNch/dη is significantly stronger than linear and dependent on the transverse momentum. The data are compared to theoretical predictions, which describe the observed trends well, albeit not always quantitatively

    Direct observation of the dead-cone effect in quantum chromodynamics

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    The direct measurement of the QCD dead cone in charm quark fragmentation is reported, using iterative declustering of jets tagged with a fully reconstructed charmed hadron

    Multiplicity dependence of K*(892)0 and ϕ(1020) production in pp collisions at t √s=13 TeV

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    The striking similarities that have been observed between high-multiplicity proton-proton (pp) collisions and heavy-ion collisions can be explored through multiplicity-differential measurements of identified hadrons in pp collisions. With these measurements, it is possible to study mechanisms such as collective flow that determine the shapes of hadron transverse momentum (pT) spectra, to search for possible modifications of the yields of short-lived hadronic resonances due to scattering effects in an extended hadron-gas phase, and to investigate different explanations provided by phenomenological models for enhancement of strangeness production with increasing multiplicity. In this paper, these topics are addressed through measurements of the K∗(892)0 and φ(1020) mesons at midrapidity in pp collisions at √s = 13 TeV as a function of the charged-particle multiplicity. The results include the pT spectra, pT-integrated yields, mean transverse momenta, and the ratios of the yields of these resonances to those of longer-lived hadrons. Comparisons with results from other collision systems and energies, as well as predictions from phenomenological models, are also discussed

    HΛ3 and H‟Λ‟3 lifetime measurement in Pb–Pb collisions at √sNN=5.02 TeV via two-body decay

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    An improved value for the lifetime of the (anti-)hypertriton has been obtained using the data sample of Pb–Pb collisions at √sNN = 5.02 TeV collected by the ALICE experiment at the LHC. The (anti-)hypertriton has been reconstructed via its charged two-body mesonic decay channel and the lifetime has been determined from an exponential fit to the dN/d(ct) spectrum. The measured value, τ = 242+34 −38 (stat.) ± 17 (syst.) ps, is compatible with representative theoretical predictions, thus contributing to the solution of the longstanding hypertriton lifetime puzzle

    Measurement of electrons from semileptonic heavy-flavour hadron decays at midrapidity in pp and Pb–Pb collisions at √sNN = 5.02 TeV

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    The differential invariant yield as a function of transverse momentum (pT) of electrons from semileptonic heavy-flavour hadron decays was measured at midrapidity in central (0–10%), semi-central (30–50%) and peripheral (60–80%) lead–lead (Pb–Pb) collisions at √sNN = 5.02 TeV in the pT intervals 0.5–26 GeV/c (0–10% and 30–50%) and 0.5–10 GeV/c (60–80%). The production cross section in proton–proton (pp) collisions at √s = 5.02 TeV was measured as well in 0.5 < pT < 10 GeV/c and it lies close to the upper band of perturbative QCD calculation uncertainties up to pT = 5 GeV/c and close to the mean value for larger pT. The modification of the electron yield with respect to what is expected for an incoherent superposition of nucleon–nucleon collisions is evaluated by measuring the nuclear modification factor RAA. The measurement of the RAA in different centrality classes allows in-medium energy loss of charm and beauty quarks to be investigated. The RAA shows a suppression with respect to unity at intermediate pT, which increases while moving towards more central collisions. Moreover, the measured RAA is sensitive to the modification of the parton distribution functions (PDF) in nuclei, like nuclear shadowing, which causes a suppression of the heavy-quark production at low pT in heavy-ion collisions at LHC

    Study of the Λ–Λ interaction with femtoscopy correlations in pp and p–Pb collisions at the LHC

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    This work presents new constraints on the existence and the binding energy of a possible – bound state, the H-dibaryon, derived from – femtoscopic measurements by the ALICE collaboration. The results are obtained from a new measurement using the femtoscopy technique in pp collisions at √s = 13 TeV and p–Pb collisions at √sNN = 5.02 TeV, combined with previously published results from pp collisions at √s = 7 TeV. The – scattering parameter space, spanned by the inverse scattering length f −1 0 and the effective range d0, is constrained by comparing the measured – correlation function with calculations obtained within the LednickĂœ model. The data are compatible with hypernuclei results and lattice computations, both predicting a shallow attractive interaction, and permit to test different theoretical approaches describing the – interaction. The region in the (f −1 0 ,d0) plane which would accommodate a – bound state is substantially restricted compared to previous studies. The binding energy of the possible – bound state is estimated within an effective-range expansion approach and is found to be B = 3.2+1.6 −2.4(stat)+1.8 −1.0(syst) MeV
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