106 research outputs found

    Genetic predisposition to hemophagocytic lymphohistiocytosis: Report on 500 patients from the Italian registry.

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    BACKGROUND: Hemophagocytic lymphohistiocytosis (HLH) is a rare life-threatening disease affecting mostly children but also adults and characterized by hyperinflammatory features. A subset of patients, referred to as having familial hemophagocytic lymphohistiocytosis (FHL), have various underlying genetic abnormalities, the frequencies of which have not been systematically determined previously. OBJECTIVE: This work aims to further our understanding of the pathogenic bases of this rare condition based on an analysis of our 25 years of experience. METHODS: From our registry, we have analyzed a total of 500 unselected patients with HLH. RESULTS: Biallelic pathogenic mutations defining FHL were found in 171 (34%) patients; the proportion of FHL was much higher (64%) in patients given a diagnosis during the first year of life. Taken together, mutations of the genes PRF1 (FHL2) and UNC13D (FHL3) accounted for 70% of cases of FHL. Overall, a genetic diagnosis was possible in more than 90% of our patients with FHL. Perforin expression and the extent of degranulation have been more useful for diagnosing FHL than hemophagocytosis and the cytotoxicity assay. Of 281 (56%) patients classified as having "sporadic" HLH, 43 had monoallelic mutations in one of the FHL-defining genes. Given this gene dosage effect, FHL is not strictly recessive. CONCLUSION: We suggest that the clinical syndrome HLH generally results from the combined effects of an exogenous trigger and genetic predisposition. Within this combination, different weights of exogenous and genetic factors account for the wide disease spectrum that ranges from HLH secondary to severe infection to FHL.Supported by grants from Associazione Italiana Ricerca Istiocitosi (AIRI), Associazione Ciemmeesse-Girotondo per il Meyer, Ministero della Salute (Bando Malattie Rare RF-TOS-2008-1219488), and the Seventh Framework Programme (FP7) of the European Commission (“FIGHT-HLH” Project no. 306124 to M.A.). Disclosure of potential conflict of interest: D. Pende receives royalties paid to her institution. G. M. Griffiths has received research support from the Wellcome Trust. L. Luzzatto is on the Alexion Pharmaceuticals SAB and has received consultancy fees from GlaxoSmithKline.This is the final version of the article. It first appeared from Elsevier via http://dx.doi.org/10.1016/j.jaci.2015.06.04

    Event reconstruction for KM3NeT/ORCA using convolutional neural networks

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    The KM3NeT research infrastructure is currently under construction at two locations in the Mediterranean Sea. The KM3NeT/ORCA water-Cherenkov neutrino detector off the French coast will instrument several megatons of seawater with photosensors. Its main objective is the determination of the neutrino mass ordering. This work aims at demonstrating the general applicability of deep convolutional neural networks to neutrino telescopes, using simulated datasets for the KM3NeT/ORCA detector as an example. To this end, the networks are employed to achieve reconstruction and classification tasks that constitute an alternative to the analysis pipeline presented for KM3NeT/ORCA in the KM3NeT Letter of Intent. They are used to infer event reconstruction estimates for the energy, the direction, and the interaction point of incident neutrinos. The spatial distribution of Cherenkov light generated by charged particles induced in neutrino interactions is classified as shower- or track-like, and the main background processes associated with the detection of atmospheric neutrinos are recognized. Performance comparisons to machine-learning classification and maximum-likelihood reconstruction algorithms previously developed for KM3NeT/ORCA are provided. It is shown that this application of deep convolutional neural networks to simulated datasets for a large-volume neutrino telescope yields competitive reconstruction results and performance improvements with respect to classical approaches

    Event reconstruction for KM3NeT/ORCA using convolutional neural networks

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    The KM3NeT research infrastructure is currently under construction at two locations in the Mediterranean Sea. The KM3NeT/ORCA water-Cherenkov neutrino de tector off the French coast will instrument several megatons of seawater with photosensors. Its main objective is the determination of the neutrino mass ordering. This work aims at demonstrating the general applicability of deep convolutional neural networks to neutrino telescopes, using simulated datasets for the KM3NeT/ORCA detector as an example. To this end, the networks are employed to achieve reconstruction and classification tasks that constitute an alternative to the analysis pipeline presented for KM3NeT/ORCA in the KM3NeT Letter of Intent. They are used to infer event reconstruction estimates for the energy, the direction, and the interaction point of incident neutrinos. The spatial distribution of Cherenkov light generated by charged particles induced in neutrino interactions is classified as shower-or track-like, and the main background processes associated with the detection of atmospheric neutrinos are recognized. Performance comparisons to machine-learning classification and maximum-likelihood reconstruction algorithms previously developed for KM3NeT/ORCA are provided. It is shown that this application of deep convolutional neural networks to simulated datasets for a large-volume neutrino telescope yields competitive reconstruction results and performance improvements with respect to classical approaches

    VERY HIGH ENERGY γ-RAYS from the UNIVERSE'S MIDDLE AGE: DETECTION of the z = 0.940 BLAZAR PKS 1441+25 with MAGIC

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    The flat-spectrum radio quasar PKS 1441+25 at a redshift of z = 0.940 is detected between 40 and 250 GeV with a significance of 25.5σ using the MAGIC telescopes. Together with the gravitationally lensed blazar QSO B0218+357 (z = 0.944), PKS 1441+25 is the most distant very high energy (VHE) blazar detected to date. The observations were triggered by an outburst in 2015 April seen at GeV energies with the Large Area Telescope on board Fermi. Multi-wavelength observations suggest a subdivision of the high state into two distinct flux states. In the band covered by MAGIC, the variability timescale is estimated to be 6.4 ±1.9 days. Modeling the broadband spectral energy distribution with an external Compton model, the location of the emitting region is understood as originating in the jet outside the broad-line region (BLR) during the period of high activity, while being partially within the BLR during the period of low (typical) activity. The observed VHE spectrum during the highest activity is used to probe the extragalactic background light at an unprecedented distance scale for ground-based gamma-ray astronomy

    Production of He-4 and (4) in Pb-Pb collisions at root(NN)-N-S=2.76 TeV at the LHC

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    Results on the production of He-4 and (4) nuclei in Pb-Pb collisions at root(NN)-N-S = 2.76 TeV in the rapidity range vertical bar y vertical bar <1, using the ALICE detector, are presented in this paper. The rapidity densities corresponding to 0-10% central events are found to be dN/dy4(He) = (0.8 +/- 0.4 (stat) +/- 0.3 (syst)) x 10(-6) and dN/dy4 = (1.1 +/- 0.4 (stat) +/- 0.2 (syst)) x 10(-6), respectively. This is in agreement with the statistical thermal model expectation assuming the same chemical freeze-out temperature (T-chem = 156 MeV) as for light hadrons. The measured ratio of (4)/He-4 is 1.4 +/- 0.8 (stat) +/- 0.5 (syst). (C) 2018 Published by Elsevier B.V.Peer reviewe

    Supplement: "Localization and broadband follow-up of the gravitational-wave transient GW150914" (2016, ApJL, 826, L13)

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    This Supplement provides supporting material for Abbott et al. (2016a). We briefly summarize past electromagnetic (EM) follow-up efforts as well as the organization and policy of the current EM follow-up program. We compare the four probability sky maps produced for the gravitational-wave transient GW150914, and provide additional details of the EM follow-up observations that were performed in the different bands

    Insights into the high-energy γ-ray emission of Markarian 501 from extensive multifrequency observations in the Fermi era

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    We report on the γ-ray activity of the blazar Mrk 501 during the first 480 days of Fermi operation. We find that the average Large Area Telescope (LAT) γ-ray spectrum of Mrk 501 can be well described by a single power-law function with a photon index of 1.78 ± 0.03. While we observe relatively mild flux variations with the Fermi-LAT (within less than a factor of two), we detect remarkable spectral variability where the hardest observed spectral index within the LAT energy range is 1.52 ± 0.14, and the softest one is 2.51 ± 0.20. These unexpected spectral changes do not correlate with the measured flux variations above 0.3 GeV. In this paper, we also present the first results from the 4.5 month long multifrequency campaign (2009 March 15-August 1) on Mrk 501, which included the Very Long Baseline Array (VLBA), Swift, RXTE, MAGIC, and VERITAS, the F-GAMMA, GASP-WEBT, and other collaborations and instruments which provided excellent temporal and energy coverage of the source throughout the entire campaign. The extensive radio to TeV data set from this campaign provides us with the most detailed spectral energy distribution yet collected for this source during its relatively low activity. The average spectral energy distribution of Mrk 501 is well described by the standard one-zone synchrotron self-Compton (SSC) model. In the framework of this model, we find that the dominant emission region is characterized by a size ≲0.1 pc (comparable within a factor of few to the size of the partially resolved VLBA core at 15-43 GHz), and that the total jet power (≃1044 erg s-1) constitutes only a small fraction (∼10-3) of the Eddington luminosity. The energy distribution of the freshly accelerated radiating electrons required to fit the time-averaged data has a broken power-law form in the energy range 0.3 GeV-10 TeV, with spectral indices 2.2 and 2.7 below and above the break energy of 20 GeV. We argue that such a form is consistent with a scenario in which the bulk of the energy dissipation within the dominant emission zone of Mrk 501 is due to relativistic, proton-mediated shocks. We find that the ultrarelativistic electrons and mildly relativistic protons within the blazar zone, if comparable in number, are in approximate energy equipartition, with their energy dominating the jet magnetic field energy by about two orders of magnitude. © 2011. The American Astronomical Society

    Assessment of ash agglomeration and fouling in combustion by theoretical and experimental biomass fuels characterization

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    Among the priorities of the EU, there is the need for harvesting large amounts of renewable energy to progress the transition to a low-carbon economy. Flexible biomass provision is envisaged for energy system predictability and for the valorization of renewable feedstock. Nevertheless, biomass is greatly varying in its physical and chemical properties: especially, the variability in the inorganic matter (ash) concentration has an impact on the fuel behaviour in conversion plants, e.g. in combustion, inducing operational challenges. Consequently, the use of opportunity fuels such as agro-residues and bio-renery wastes, is limited. In fact, the current characterization of biomass has a limited value for operational decisions. The objective of this Thesis, developed in collaboration with ENGIE Electrabel, is to develop tools for the biomass characterization with a focus on ash challenges in combustion: agglomeration, slagging and fouling. After the introduction, a model to compute the fuel propensities to induce agglomeration - slagging issues as a function of the ash composition is presented. Such simplied model is applied to characterize unconventional Mediterranean fuels. As a second step, a more fundamental approach based on equilibrium phase diagrams (e.g. K2O-SiO2-CaO) and thermochemical equilibrium calculations is proposed and applied to ten opportunity fuels. Computational and experimental tools are integrated with the development and the validation of a 5-step fuel characterization methodology applied to four woody fuels, including tests in a circulating fluidized bed pilot reactor. A detailed study on fouling of sunflower husks burned with mineral additives, including tests in a drop tube furnace, is nally addressed. The characterization tools developed and validated in this Thesis allow, given a specic fuel, the preliminary evaluation of the risk of ash challenges in combustion: the key for an ecient fuel screening with the objective of operational excellence.(FSA - Sciences de l'ingénieur) -- UCL, 201

    Insight into electric utility business models for high-share renewables and storage integration

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    Since a few years, energy utilities are facing business model disruptions: grid parity of renewable technologies, stable or decreasing demand - especially in the EU -, acceleration of digital innovations within the smart-home market, uncertain policy directives and influential customers' opinions. If, in the past, the lack of entrepreneurial culture within large companies has caused losses of market shares towards smaller, innovative, more digitally mature companies or energy co-operatives, since the last 2-4 years, some utilities have been exploring pathways to fit the energy services demand of customers, in parallel to the requirements from investors and regulators. In this investigation, after a summary of the current status of the energy transition in the EU, emerging business models for the future utility are presented, in a tentative of drawing an updated overview of the current market mutations. The emerging role of the electric energy storage systems within the studied business models is detailed, including the illustration of specific pilot cases, for which technical and economic information are compared

    A modelling approach for the assessment of an air-dryer economic feasibility for small-scale biomass steam boilers

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    Fuel drying is an energetically and economically expensive pretreatment process, which may not be worth the investment in the case of small-scale generation plants. This paper presents an investigation on the air dryer feasibility to enhance the operation of biomass steam boiler. In the proposed approach, the external drying technology using preheated air and the biomass steam production system is modelled in terms of energy and an economical analysis. A focus is given to the system size influence on the dryer economic suitability: the smallest size of the biomass combustion system for which fuel drying is a suitable solution, from the economic point of view, is computed. In the computations, the heat used for drying is assumed to be part of the cost for operating the dryer and the thermal balance of the system is assumed to be previously verified. According to the model results, if the steam production plant operational time is above 8000 h/y, wood chips drying is feasible if the system size is larger than 1.78 tdaf/h of fuel processed
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