359 research outputs found

    Discovering people's relationships with nature in central Chile : a case study in a peri-urban commune.

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    La valoración social de la vida silvestre es reconocida como esencial para lograr una conservación biológica efectiva. Esto se fundamenta en la comprensión de las relaciones de las personas con la vida silvestre. Esta necesidad ya ha sido planteada en el contexto de las políticas ambientales internacionales. En Chile, ha sido explícitamente mencionada como relevante en la Estrategia Nacional de Biodiversidad, que declara la necesidad de un mejor entendimiento de cómo los ciudadanos chilenos están utilizando y valorando la biodiversidad. Sin embargo, en Chile aún existe poca evidencia científica al respecto. El presente artículo tiene como objetivo analizar las relaciones que las personas tienen con la naturaleza de su territorio de tal forma de establecer cuáles son las visiones que tienen sobre la fauna y flora. El estudio se desarrolla en un área periurbana de la Región Metropolitana de Santiago de Chile. El enfoque utilizado para el análisis de las relaciones personas-vida silvestre fue cualitativo, con base en la Teoría Fundamentada. A través del estudio se evidenció que la naturaleza es identificada por los habitantes por medio de elementos tangibles de su entorno natural, la cual se constituye a través de una relación entre el individuo, la sociedad y el mundo físico. Los resultados muestran una gran importancia de los bosques de quillay (Quillaja saponaria) para los participantes lo cual da luces sobre la relevancia que tiene el contexto sociocultural en el cual se llevan a cabo las valoraciones sociales de la vida silvestre, dado que en este tipo de estudios la fauna generalmente emerge como más relevante. En Chile, a excepción de unos pocos estudios científicos, existen muy pocas experiencias publicadas que aborden la importancia social de plantas particulares. Con este estudio pretendemos aportar a la literatura científica con un estudio de caso así como también contribuir a la gestión de la conservación del área.The social assessment of wildlife is recognized as essential to achieve effective biological conservation. This is based on the understanding of people's relationships with wildlife. This need has already been raised in the context of international environmental policies. In Chile, it has been explicitly mentioned as relevant in the National Biodiversity Strategy, which declares the need for a better understanding of how Chilean citizens are using and valuing biodiversity. However, in Chile there is still little scientific evidence in this regard. This article aims to analyze the relationships that people have with nature in their territory in order to establish what the visions that they have on fauna and flora are. The study is carried out in a peri-urban area of the Metropolitan Region of Santiago de Chile. The approach used for the analysis of people-wildlife relationships was qualitative, based on the Grounded Theory. Through the study it was shown that nature is identified by the inhabitants through tangible elements of their natural environment, which is constituted through a relationship between the individual, society and the physical world. The results show a great importance of the quillay forests (Quillaja saponaria) for the participants which gives light on the relevance of the socio-cultural context in which social assessment of wildlife are carried out, given that in this type of studies fauna generally emerges as more relevant. With the exception of a few scientific studies, there are very few published experiences in Chile that address the social importance of particular plants. This study intends to contribute to the scientific literature with a case study, as well as to contribute to the management of the conservation of the area

    Search for new particles in events with energetic jets and large missing transverse momentum in proton-proton collisions at root s=13 TeV

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    A search is presented for new particles produced at the LHC in proton-proton collisions at root s = 13 TeV, using events with energetic jets and large missing transverse momentum. The analysis is based on a data sample corresponding to an integrated luminosity of 101 fb(-1), collected in 2017-2018 with the CMS detector. Machine learning techniques are used to define separate categories for events with narrow jets from initial-state radiation and events with large-radius jets consistent with a hadronic decay of a W or Z boson. A statistical combination is made with an earlier search based on a data sample of 36 fb(-1), collected in 2016. No significant excess of events is observed with respect to the standard model background expectation determined from control samples in data. The results are interpreted in terms of limits on the branching fraction of an invisible decay of the Higgs boson, as well as constraints on simplified models of dark matter, on first-generation scalar leptoquarks decaying to quarks and neutrinos, and on models with large extra dimensions. Several of the new limits, specifically for spin-1 dark matter mediators, pseudoscalar mediators, colored mediators, and leptoquarks, are the most restrictive to date.Peer reviewe

    Mortality and pulmonary complications in patients undergoing surgery with perioperative SARS-CoV-2 infection: an international cohort study

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    Background: The impact of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on postoperative recovery needs to be understood to inform clinical decision making during and after the COVID-19 pandemic. This study reports 30-day mortality and pulmonary complication rates in patients with perioperative SARS-CoV-2 infection. Methods: This international, multicentre, cohort study at 235 hospitals in 24 countries included all patients undergoing surgery who had SARS-CoV-2 infection confirmed within 7 days before or 30 days after surgery. The primary outcome measure was 30-day postoperative mortality and was assessed in all enrolled patients. The main secondary outcome measure was pulmonary complications, defined as pneumonia, acute respiratory distress syndrome, or unexpected postoperative ventilation. Findings: This analysis includes 1128 patients who had surgery between Jan 1 and March 31, 2020, of whom 835 (74·0%) had emergency surgery and 280 (24·8%) had elective surgery. SARS-CoV-2 infection was confirmed preoperatively in 294 (26·1%) patients. 30-day mortality was 23·8% (268 of 1128). Pulmonary complications occurred in 577 (51·2%) of 1128 patients; 30-day mortality in these patients was 38·0% (219 of 577), accounting for 81·7% (219 of 268) of all deaths. In adjusted analyses, 30-day mortality was associated with male sex (odds ratio 1·75 [95% CI 1·28–2·40], p\textless0·0001), age 70 years or older versus younger than 70 years (2·30 [1·65–3·22], p\textless0·0001), American Society of Anesthesiologists grades 3–5 versus grades 1–2 (2·35 [1·57–3·53], p\textless0·0001), malignant versus benign or obstetric diagnosis (1·55 [1·01–2·39], p=0·046), emergency versus elective surgery (1·67 [1·06–2·63], p=0·026), and major versus minor surgery (1·52 [1·01–2·31], p=0·047). Interpretation: Postoperative pulmonary complications occur in half of patients with perioperative SARS-CoV-2 infection and are associated with high mortality. Thresholds for surgery during the COVID-19 pandemic should be higher than during normal practice, particularly in men aged 70 years and older. Consideration should be given for postponing non-urgent procedures and promoting non-operative treatment to delay or avoid the need for surgery. Funding: National Institute for Health Research (NIHR), Association of Coloproctology of Great Britain and Ireland, Bowel and Cancer Research, Bowel Disease Research Foundation, Association of Upper Gastrointestinal Surgeons, British Association of Surgical Oncology, British Gynaecological Cancer Society, European Society of Coloproctology, NIHR Academy, Sarcoma UK, Vascular Society for Great Britain and Ireland, and Yorkshire Cancer Research

    Probing effective field theory operators in the associated production of top quarks with a Z boson in multilepton final states at root s=13 TeV

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    Measurement of the Higgs boson production rate in association with top quarks in final states with electrons, muons, and hadronically decaying tau leptons at s√=13TeV

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    The rate for Higgs (H) bosons production in association with either one (tH) or two (tt¯H) top quarks is measured in final states containing multiple electrons, muons, or tau leptons decaying to hadrons and a neutrino, using proton–proton collisions recorded at a center-of-mass energy of 13TeV by the CMS experiment. The analyzed data correspond to an integrated luminosity of 137fb−1. The analysis is aimed at events that contain H→WW, H→ττ, or H→ZZ decays and each of the top quark(s) decays either to lepton+jets or all-jet channels. Sensitivity to signal is maximized by including ten signatures in the analysis, depending on the lepton multiplicity. The separation among tH, tt¯H, and the backgrounds is enhanced through machine-learning techniques and matrix-element methods. The measured production rates for the tt¯H and tH signals correspond to 0.92±0.19(stat)+0.17−0.13(syst) and 5.7±2.7(stat)±3.0(syst) of their respective standard model (SM) expectations. The corresponding observed (expected) significance amounts to 4.7 (5.2) standard deviations for tt¯H, and to 1.4 (0.3) for tH production. Assuming that the Higgs boson coupling to the tau lepton is equal in strength to its expectation in the SM, the coupling yt of the Higgs boson to the top quark divided by its SM expectation, κt=yt/ySMt, is constrained to be within −0.9<κt<−0.7 or 0.7<κt<1.1, at 95% confidence level. This result is the most sensitive measurement of the tt¯H production rate to date.SCOAP

    Observation of triple J/ψ\psi meson production in proton-proton collisions at s\sqrt{s} = 13 TeV

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    The first observation of the simultaneous production of three J/ψ\psi mesons in proton-proton (pp) collisions is presented, based on a data sample collected by the CMS experiment at a center-of-mass energy of 13 TeV and corresponding to an integrated luminosity of 133 fb1^{-1}. The pp \to J/ψ\psi\,J/ψ\psi\,J/ψ\psi\,X process is observed with a significance above five standard deviations in final states with three μ+μ\mu^+\mu^- pairs. The measured inclusive fiducial cross section of σ\sigma(pp \to J/ψ\psi\,J/ψ\psi\,J/ψ\psi\,X)= 272104+141^{+141}_{-104} (stat) ±\pm 17 (syst) fb is compared to theoretical expectations for the production of three J/ψ\psi mesons in single- (SPS), double- (DPS), and triple- (TPS) parton scatterings. Assuming factorization of multiple hard-scattering probabilities in terms of SPS cross sections, the measured process is found to be dominated by DPS and TPS contributions, and an effective DPS cross section, related to the transverse distribution of partons in the proton, of σeff,DPS\sigma_\mathrm{eff,DPS} = 2.71.0+1.4^{+1.4}_{-1.0} (exp) 1.0+1.5{}^{+1.5}_{-1.0} (theo) mb is determined

    First evidence for off-shell production of the Higgs boson and measurement of its width

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    The first evidence for off-shell Higgs production is reported in the final state with two Z bosons decaying into either four charged leptons (muons or electrons), or two charged leptons and two neutrinos, and a measurement of the Higgs boson width is performed. Results are based on data from the CMS experiment at the LHC at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of up to 140 fb1^{-1}. The total rate of off-shell Higgs boson production beyond the Z boson pair production threshold, relative to its standard model expectation, is constrained to the interval [0.0061, 2.0] at 95% confidence level. The scenario with no off-shell production is excluded at 99.97% confidence level (3.6 standard deviations). The width of the Higgs boson is extracted as ΓH\Gamma_{\mathrm{H}} = 3.21.7+2.4_{-1.7}^{+2.4} MeV, in agreement with the standard model expectation of 4.1 MeV. The data are also used to set new constraints on anomalous Higgs boson couplings to W and Z boson pairs

    Measurement of the inclusive and differential ttˉγ\mathrm{t\bar{t}}\gamma cross sections in the dilepton channel and effective field theory interpretation in proton-proton collisions at s\sqrt{s} =13 TeV

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    The production cross section of a top quark pair in association with a photon is measured in proton-proton collisions in the decay channel with two oppositely charged leptons (e±μ^\pm\mu^\mp, e+^+e^-, or μ+μ\mu^+\mu^-). The measurement is performed using 138 fb1^{-1} of proton-proton collision data recorded by the CMS experiment at s\sqrt{s} =13 TeV during the 2016-2018 data-taking period of the CERN LHC. A fiducial phase space is defined such that photons radiated by initial-state particles, top quarks, or any of their decay products are included. An inclusive cross section of 173.5 ±\pm 2.5 (stat) ±\pm 6.3 (syst) fb is measured in a signal region with at least one jet coming from the hadronization of a bottom quark and exactly one photon with transverse momentum above 20 GeV. Differential cross sections are measured as functions of several kinematic observables of the photon, leptons, and jets, and compared to standard model predictions. The measurements are also interpreted in the standard model effective field theory framework, and limits are found on the relevant Wilson coefficients from these results alone and in combination with a previous CMS measurement of the ttˉγ\mathrm{t\bar{t}}\gamma production process using the lepton+jets final state

    Evidence for WW/WZ vector boson scattering in the decay channel ν\ell\nuqq produced in association with two jets in proton-proton collisions at s\sqrt{s} = 13 TeV

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    Evidence is reported for electroweak (EW) vector boson scattering in the decay channel ν\ell\nuqq of two weak vector bosons WV (V = W or Z), produced in association with two parton jets. The search uses a data set of proton-proton collisions at 13 TeV collected with the CMS detector during 2016-2018 with an integrated luminosity of 138 fb1^{-1}. Events are selected requiring one lepton (electron or muon), moderate missing transverse momentum, two jets with a large pseudorapidity separation and a large dijet invariant mass, and a signature consistent with the hadronic decay of a W/Z boson. The cross section is computed in a fiducial phase space defined at parton level requiring all parton transverse momenta pT>p_\mathrm{T} \gt 10 GeV and at least one pair of outgoing partons with invariant mass mqq>m_\mathrm{qq}\gt 100 GeV. The measured and expected EW WV production cross sections are 1.900.46+0.53^{+0.53}_{-0.46} pb and 2.230.11+0.08^{+0.08}_{-0.11} (scale) ±\pm 0.05(PDF) pb, respectively, where PDF is the parton distribution function. The observed EW signal strength is mEWm_\mathrm{EW} = 0.85 pmpm 0.12 (stat)0.17+0.19^{+0.19}_{-0.17} (syst), corresponding to a signal significance of 4.4 standard deviations with 5.1 expected. This is the first evidence of vector boson scattering in the ν\ell\nuqq decay channel at LHC. The simultaneous measurement of the EW and quantum chromodynamics associated diboson production agrees with the standard model prediction
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