162 research outputs found

    Knowledge structure representation and automated updates in intelligent information management systems

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    A continuing effort to apply rapid prototyping and Artificial Intelligence techniques to problems associated with projected Space Station-era information management systems is examined. In particular, timely updating of the various databases and knowledge structures within the proposed intelligent information management system (IIMS) is critical to support decision making processes. Because of the significantly large amounts of data entering the IIMS on a daily basis, information updates will need to be automatically performed with some systems requiring that data be incorporated and made available to users within a few hours. Meeting these demands depends first, on the design and implementation of information structures that are easily modified and expanded, and second, on the incorporation of intelligent automated update techniques that will allow meaningful information relationships to be established. Potential techniques are studied for developing such an automated update capability and IIMS update requirements are examined in light of results obtained from the IIMS prototyping effort

    A rapid prototyping/artificial intelligence approach to space station-era information management and access

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    Applications of rapid prototyping and Artificial Intelligence techniques to problems associated with Space Station-era information management systems are described. In particular, the work is centered on issues related to: (1) intelligent man-machine interfaces applied to scientific data user support, and (2) the requirement that intelligent information management systems (IIMS) be able to efficiently process metadata updates concerning types of data handled. The advanced IIMS represents functional capabilities driven almost entirely by the needs of potential users. Space Station-era scientific data projected to be generated is likely to be significantly greater than data currently processed and analyzed. Information about scientific data must be presented clearly, concisely, and with support features to allow users at all levels of expertise efficient and cost-effective data access. Additionally, mechanisms for allowing more efficient IIMS metadata update processes must be addressed. The work reported covers the following IIMS design aspects: IIMS data and metadata modeling, including the automatic updating of IIMS-contained metadata, IIMS user-system interface considerations, including significant problems associated with remote access, user profiles, and on-line tutorial capabilities, and development of an IIMS query and browse facility, including the capability to deal with spatial information. A working prototype has been developed and is being enhanced

    Search for Higgs boson decays to a Z boson and a photon in proton-proton collisions at s \sqrt{s} = 13 TeV

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    Results are presented from a search for the Higgs boson decay H\toZγ\gamma, where Z+\to\ell^+\ell^- with \ell = e or μ\mu. The search is performed using a sample of proton-proton (pp) collision data at a center-of-mass energy of 13 TeV, recorded by the CMS experiment at the LHC, corresponding to an integrated luminosity of 138 fb1^{-1}. Events are assigned to mutually exclusive categories, which exploit differences in both event topology and kinematics of distinct Higgs production mechanisms to enhance signal sensitivity. The signal strength μ\mu, defined as the product of the cross section and the branching fraction [σ(\sigma(pp\toH)B()\mathcal{B}(H\toZγ)\gamma)] relative to the standard model prediction, is extracted from a simultaneous fit to the +γ\ell^+\ell^-\gamma invariant mass distributions in all categories and is found to be μ\mu=2.4±\pm0.9 for a Higgs boson mass of 125.38 GeV. The statistical significance of the observed excess of events is 2.7 standard deviations. This measurement corresponds to σ(\sigma(pp\toH)B()\mathcal{B}(H\toZγ)\gamma) = 0.21±\pm0.08 pb. The observed (expected) upper limit at 95% confidence level on μ\mu is 4.1 (1.8). The ratio of branching fractions B(\mathcal{B}(H\toZγ)/B(\gamma)/\mathcal{B}(Hγγ)\to\gamma\gamma) is measured to be 1.50.6+0.7^{+0.7}_{-0.6}, which agrees with the standard model prediction of 0.69 ±\pm 0.04 at the 1.5 standard deviation level

    Geoeconomic variations in epidemiology, ventilation management, and outcomes in invasively ventilated intensive care unit patients without acute respiratory distress syndrome: a pooled analysis of four observational studies

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    Background: Geoeconomic variations in epidemiology, the practice of ventilation, and outcome in invasively ventilated intensive care unit (ICU) patients without acute respiratory distress syndrome (ARDS) remain unexplored. In this analysis we aim to address these gaps using individual patient data of four large observational studies. Methods: In this pooled analysis we harmonised individual patient data from the ERICC, LUNG SAFE, PRoVENT, and PRoVENT-iMiC prospective observational studies, which were conducted from June, 2011, to December, 2018, in 534 ICUs in 54 countries. We used the 2016 World Bank classification to define two geoeconomic regions: middle-income countries (MICs) and high-income countries (HICs). ARDS was defined according to the Berlin criteria. Descriptive statistics were used to compare patients in MICs versus HICs. The primary outcome was the use of low tidal volume ventilation (LTVV) for the first 3 days of mechanical ventilation. Secondary outcomes were key ventilation parameters (tidal volume size, positive end-expiratory pressure, fraction of inspired oxygen, peak pressure, plateau pressure, driving pressure, and respiratory rate), patient characteristics, the risk for and actual development of acute respiratory distress syndrome after the first day of ventilation, duration of ventilation, ICU length of stay, and ICU mortality. Findings: Of the 7608 patients included in the original studies, this analysis included 3852 patients without ARDS, of whom 2345 were from MICs and 1507 were from HICs. Patients in MICs were younger, shorter and with a slightly lower body-mass index, more often had diabetes and active cancer, but less often chronic obstructive pulmonary disease and heart failure than patients from HICs. Sequential organ failure assessment scores were similar in MICs and HICs. Use of LTVV in MICs and HICs was comparable (42·4% vs 44·2%; absolute difference -1·69 [-9·58 to 6·11] p=0·67; data available in 3174 [82%] of 3852 patients). The median applied positive end expiratory pressure was lower in MICs than in HICs (5 [IQR 5-8] vs 6 [5-8] cm H2O; p=0·0011). ICU mortality was higher in MICs than in HICs (30·5% vs 19·9%; p=0·0004; adjusted effect 16·41% [95% CI 9·52-23·52]; p<0·0001) and was inversely associated with gross domestic product (adjusted odds ratio for a US$10 000 increase per capita 0·80 [95% CI 0·75-0·86]; p<0·0001). Interpretation: Despite similar disease severity and ventilation management, ICU mortality in patients without ARDS is higher in MICs than in HICs, with a strong association with country-level economic status

    Search for direct pair production of supersymmetric partners of τ\tau leptons in the final state with two hadronically decaying τ\tau leptons and missing transverse momentum in proton-proton collisions at s\sqrt{s} = 13 TeV

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    A search for the direct production of a pair of ττ sleptons, the supersymmetric partners of ττ leptons, is presented. Each ττ slepton is assumed to decay to a ττ lepton and the lightest supersymmetric particle (LSP), which is assumed to be stable and to not interact in the detector, leading to an imbalance in the total reconstructed transverse momentum. The search is carried out in events identified as containing two ττ leptons, each decaying to one or more hadrons and a neutrino, and significant transverse momentum imbalance. In addition to scenarios in which the ττ sleptons decay promptly, the search also addresses scenarios in which the ττ sleptons have sufficiently long lifetimes to give rise to nonprompt ττ leptons. The data were collected in proton-proton collisions at a center-of-mass energy of 13 TeV at the CERN LHC with the CMS detector in 2016–2018, and correspond to an integrated luminosity of 138 fb1^{-1}. No significant excess is seen with respect to standard model expectations. Upper limits on cross sections for the pair production of ττ sleptons are obtained in the framework of simplified models. In a scenario in which the ττ sleptons are superpartners of left-handed ττ leptons, and each undergoes a prompt decay to a ττ lepton and a nearly massless LSP, ττ slepton masses between 115 and 340 GeV are excluded. In a scenario in which the lifetime of the ττ sleptons corresponds to cτ0cτ_0 = 0.1 mm, where τ0τ_0 represents the mean proper lifetime of the ττ slepton, masses between 150 and 220 GeV are excluded

    Constraints on anomalous Higgs boson couplings to vector bosons and fermions from the production of Higgs bosons using the ττ final state

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    A study of anomalous couplings of the Higgs boson to vector bosons and fermions is presented. The data were recorded by the CMS experiment at a center-of-mass energy of pp collisions at the LHC of 13 TeV and correspond to an integrated luminosity of 138 fb-1. The study uses Higgs boson candidates produced mainly in gluon fusion or electroweak vector boson fusion at the LHC that subsequently decay to a pair of τ leptons. Matrix-element and machine-learning techniques were employed in a search for anomalous interactions. The results are combined with those from the four-lepton and two-photon decay channels to yield the most stringent constraints on anomalous Higgs boson couplings to date. The pure CP-odd scenario of the Higgs boson coupling to gluons is excluded at 2.4 standard deviations. The results are consistent with the standard model predictions

    Search for light Higgs bosons from supersymmetric cascade decays in pp\text {pp} collisions at s=13TeV\sqrt{s}=13\,\textrm{TeV}

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    A search is reported for pairs of light Higgs bosons (H1{\textrm{H}} _1) produced in supersymmetric cascade decays in final states with small missing transverse momentum. A data set of LHC pp\hbox {pp} collisions collected with the CMS detector at s=13TeV\sqrt{s}=13\,\text {TeV} and corresponding to an integrated luminosity of 138fb1\,\text {fb}^{-1} is used. The search targets events where both H1{\textrm{H}} _1 bosons decay into pairs that are reconstructed as large-radius jets using substructure techniques. No evidence is found for an excess of events beyond the background expectations of the standard model (SM). Results from the search are interpreted in the next-to-minimal supersymmetric extension of the SM, where a “singlino” of small mass leads to squark and gluino cascade decays that can predominantly end in a highly Lorentz-boosted singlet-like H1{\textrm{H}} _1 and a singlino-like neutralino of small transverse momentum. Upper limits are set on the product of the squark or gluino pair production cross section and the square of the branching fraction of the H1{\textrm{H}} _1 in a benchmark model containing almost mass-degenerate gluinos and light-flavour squarks. Under the assumption of an SM-like branching fraction, H1{\textrm{H}} _1 bosons with masses in the range 40–120GeV\,\text {GeV} arising from the decays of squarks or gluinos with a mass of 1200–2500GeV\,\text {GeV} are excluded at 95% confidence level

    Measurements of Higgs boson production in the decay channel with a pair of τ\tau leptons in proton–proton collisions at s=13\sqrt{s}=13 TeV

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    Measurements of Higgs boson production, where the Higgs boson decays into a pair of τ\tau leptons, are presented, using a sample of proton-proton collisions collected with the CMS experiment at a center-of-mass energy of , corresponding to an integrated luminosity of 138fb1\,\text {fb}^{-1}. Three analyses are presented. Two are targeting Higgs boson production via gluon fusion and vector boson fusion: a neural network based analysis and an analysis based on an event categorization optimized on the ratio of signal over background events. These are complemented by an analysis targeting vector boson associated Higgs boson production. Results are presented in the form of signal strengths relative to the standard model predictions and products of cross sections and branching fraction to τ\tau leptons, in up to 16 different kinematic regions. For the simultaneous measurements of the neural network based analysis and the analysis targeting vector boson associated Higgs boson production signal strengths are found to be 0.82±0.110.82\pm 0.11 for inclusive Higgs boson production, 0.67±0.190.67\pm 0.19 (0.81±0.170.81\pm 0.17) for the production mainly via gluon fusion (vector boson fusion), and 1.79±0.451.79\pm 0.45 for vector boson associated Higgs boson production
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