990 research outputs found

    Size-resolved particle measurements of polybrominated diphenyl ethers indoors: Implications for sources and human exposure

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    Polybrominated diphenyl ethers (PBDEs) are flame retardant polymer additives that are widely detected in outdoor and indoor environments. Release of PBDEs from consumer products leads to high concentrations indoors, but mechanisms of release are poorly understood. While ingestion of dust is a well-studied indoor PBDE exposure route, the importance of inhalation exposure is uncertain. To address these unknowns, dust was collected from household vacuum cleaners, and suspended particulate matter (PM) was collected from the same homes in St. John’s, Canada using a cascade impactor. Size-fractionated PM samples (0.01-18 ”m diameter) were analysed for PBDEs. The sum of PBDEs in all PM ranged from 8.7 ± 0.5 to 15.7 ± 0.5 pg/m3, with >50% of PBDE mass in respirable PM (<1 ”m). Mass loadings as a function of particle size suggested both abrasion and off-gassing led to the presence of PBDEs in PM. Variability in the PM mass loadings indicated emission mechanisms were both product- and location-dependent. Congener profiles in co-located vacuum dust and PM samples were different, indicating vacuum dust cannot accurately predict PBDE congeners in respirable PM. A calculated lower limit inhalation exposure to PBDEs (0.19 ng/day) is lower than exposure via diet or ingestion of dust, although the different biochemical pathways for inhalation compared to ingestion may have biological effects. This work highlights the importance of contaminant analysis in size-fractionated PM to assess human exposure via inhalation compared to traditional vacuum dust methods

    Analysis of Potential Benefits and Costs of Adopting a Commercial Building Energy Standard in South Dakota

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    The state of South Dakota is considering adopting a commercial building energy standard. This report evaluates the potential costs and benefits to South Dakota residents from requiring compliance with the most recent edition of the ANSI/ASHRAE/IESNA 90.1-2001 Energy Standard for Buildings except Low-Rise Residential Buildings. These standards were developed in an effort to set minimum requirements for the energy efficient design and construction of new commercial buildings. The quantitative benefits and costs of adopting a commercial building energy code are modeled by comparing the characteristics of assumed current building practices with the most recent edition of the ASHRAE Standard, 90.1-2001. Both qualitative and quantitative benefits and costs are assessed in this analysis. Energy and economic impacts are estimated using results from a detailed building simulation tool (Building Loads Analysis and System Thermodynamics [BLAST] model) combined with a Life-Cycle Cost (LCC) approach to assess corresponding economic costs and benefits

    Observation of Cosmic Ray Anisotropy with Nine Years of IceCube Data

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    Neutrino Education, Outreach, and Communications Activities: Captivating Examples from IceCube

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    Development and validation of HERWIG 7 tunes from CMS underlying-event measurements

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    This paper presents new sets of parameters (“tunes”) for the underlying-event model of the HERWIG7 event generator. These parameters control the description of multiple-parton interactions (MPI) and colour reconnection in HERWIG7, and are obtained from a fit to minimum-bias data collected by the CMS experiment at s=0.9, 7, and 13Te. The tunes are based on the NNPDF 3.1 next-to-next-to-leading-order parton distribution function (PDF) set for the parton shower, and either a leading-order or next-to-next-to-leading-order PDF set for the simulation of MPI and the beam remnants. Predictions utilizing the tunes are produced for event shape observables in electron-positron collisions, and for minimum-bias, inclusive jet, top quark pair, and Z and W boson events in proton-proton collisions, and are compared with data. Each of the new tunes describes the data at a reasonable level, and the tunes using a leading-order PDF for the simulation of MPI provide the best description of the dat

    MUSiC : a model-unspecific search for new physics in proton-proton collisions at root s=13TeV

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    Results of the Model Unspecific Search in CMS (MUSiC), using proton-proton collision data recorded at the LHC at a centre-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 35.9 fb(-1), are presented. The MUSiC analysis searches for anomalies that could be signatures of physics beyond the standard model. The analysis is based on the comparison of observed data with the standard model prediction, as determined from simulation, in several hundred final states and multiple kinematic distributions. Events containing at least one electron or muon are classified based on their final state topology, and an automated search algorithm surveys the observed data for deviations from the prediction. The sensitivity of the search is validated using multiple methods. No significant deviations from the predictions have been observed. For a wide range of final state topologies, agreement is found between the data and the standard model simulation. This analysis complements dedicated search analyses by significantly expanding the range of final states covered using a model independent approach with the largest data set to date to probe phase space regions beyond the reach of previous general searches.Peer reviewe

    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
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