2,232 research outputs found

    Garigliano nuclear power plant: seismic evaluation of the turbine building

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    The Italian Garigliano Nuclear Power Plant (NPP) started its energy production in 1963. At present it is in the decommissioning stage. In order to get a proper management of the radioactive waste that will be produced during the dismantling operations it has been considered convenient to convert the turbine building of the plant into a temporary waste repository. This decision posed a remarkable seismic safety assessment issue. As a matter of fact, the challenge was to extend, in satisfactory safety conditions, the use of an important facility that has reached the end of its designed lifetime and to have this extended use approved by nuclear safety agencies. In this context many tasks have been accomplished, of which the most important are: (a) a new appraisal of site seismic hazard; (b) the execution of many investigations and testing on the construction materials; (c) the set up of a detailed 3D finite element model including the explicit representation of foundation piles and soil; (d) consideration of soil structure kinematic and dynamic nteraction effects. This paper describes the adopted seismic safety assessment criteria which are based on a performance objectives design approach. While performance based design is the approach currently recommended by European Regulations to manage seismic risk and it is fully incorporated in the Italian code for conventional buildings, bridges and plants, NPP are not explicitly considered. Therefore it was necessary to delineate a consistent interpretation of prescribed rules in order to properly select the maximum and operating design earthquakes on one side and corresponding acceptable limit states on the other side. The paper further provides an outline of the numerical analyses carried out, of the main results obtained and of the principal retrofitting actions that will be realized

    Londra si muove bene

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    Analisi delle politiche di tassazione veicolare a Londr

    Yokoyama procedure efficacy on non-highly myopic patients with acquired esotropia and hypotropia

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    Objective: To assess the efficacy of \u201cYokoyama Procedure,\u201d on non-highly myopic patients with acquired esotropia and hypotropia. Methods: The study involved 10 eyes of 5 patients with eso-hypotropia. Inclusion criteria were acquired esotropic-hypotropic strabismus with lateral rectus inferior displacement and superior rectus nasal displacement confirmed by magnetic resonance imaging, refractive errors between \ub16 D, and axial length < 27 mm. Range of full duction movements and maximum angles of abduction-sursumduction was measured in each eye before and after surgery. All patients underwent T1- and T2-weighted magnetic resonance imaging. The surgery was aimed at creating a junction between the muscle bellies of the superior and lateral rectus muscles. This junction was made approximately 14 mm behind the insertions using a non-absorbable mersilene 5/0 suture (Yokoyama procedure). Results: Mean patient age was 64.8 \ub1 4.8 years. The mean globe axial length was 25.4 \ub1 0.76 mm and a mean corresponding spherical equivalent refraction of 123.7 \ub1 1.7 D was observed. Eight eyes on 10 had mild limitation in abduction, while the remaining 2 had no limitation. Three out of 10 eyes showed a moderate limited sursumduction, 5 eyes were categorized as mild, and the remaining 2 had no limitation. No evident post-operative limitation was present in any eye, in both abduction and sursumduction (p < 0.01). Pre-operative esotropia and hypotropia were, respectively, 32 \ub1 11 prismatic diopters and 25 \ub1 5 prismatic diopters, and they were significantly reduced after surgery as 9 \ub1 1.7 prismatic diopters and 6 \ub11 prismatic diopters (p = 0.043), respectively. Conclusion: Yokoyama procedure is an effective, fast, reversible procedure to face eso-hypotropic acquired strabismus, even in patients with a clear magnetic resonance imaging displacement of superior and lateral rectus muscles, and absence of globe dislocation and of elevated myopia

    Spatial-temporal modelling of disease risk accounting for PM2.5 exposure in the province of pavia: An area of the Po valley

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    Spatio-temporal Bayesian disease mapping is the branch of spatial epidemiology interested in providing valuable risk estimates in certain geographical regions using administrative areas as statistical units. The aim of the present paper is to describe spatio-temporal distribution of cardiovascular mortality in the Province of Pavia in 2010 through 2015 and assess its association with environmental pollution exposure. To produce reliable risk estimates, eight different models (hierarchical log-linear model) have been assessed: temporal parametric trend components were included together with some random effects that allowed the accounting of spatial structure of the region. The Bayesian approach allowed the borrowing information effect, including simpler model results in the more complex setting. To compare these models, Watanabe–Akaike Information Criteria (WAIC) and Leave One Out Information Criteria (LOOIC) were applied. In the modelling phase, the relationship between the disease risk and pollutants exposure (PM2.5) accounting for the urbanisation level of each geographical unit showed a strong significant effect of the pollutant exposure (OR = 1.075 and posterior probability, or PP, >0.999, equivalent to p < 0.001). A high-risk cluster of Cardiovascular mortality in the Lomellina subareas in the studied window was identified

    Results and recommendations from an intercomparison of six Hygroscopicity-TDMA systems

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    The performance of six custom-built Hygrocopicity-Tandem Differential Mobility Analyser (H-TDMA) systems was investigated in the frame of an international calibration and intercomparison workshop held in Leipzig, February 2006. The goal of the workshop was to harmonise H-TDMA measurements and develop recommendations for atmospheric measurements and their data evaluation. The H-TDMA systems were compared in terms of the sizing of dry particles, relative humidity (RH) uncertainty, and consistency in determination of number fractions of different hygroscopic particle groups. The experiments were performed in an air-conditioned laboratory using ammonium sulphate particles or an external mixture of ammonium sulphate and soot particles. The sizing of dry particles of the six H-TDMA systems was within 0.2 to 4.2% of the selected particle diameter depending on investigated size and individual system. Measurements of ammonium sulphate aerosol found deviations equivalent to 4.5% RH from the set point of 90% RH compared to results from previous experiments in the literature. Evaluation of the number fraction of particles within the clearly separated growth factor modes of a laboratory generated externally mixed aerosol was done. The data from the H-TDMAs was analysed with a single fitting routine to investigate differences caused by the different data evaluation procedures used for each H-TDMA. The differences between the H-TDMAs were reduced from +12/-13% to +8/-6% when the same analysis routine was applied. We conclude that a common data evaluation procedure to determine number fractions of externally mixed aerosols will improve the comparability of H-TDMA measurements. It is recommended to ensure proper calibration of all flow, temperature and RH sensors in the systems. It is most important to thermally insulate the aerosol humidification unit and the second DMA and to monitor these temperatures to an accuracy of 0.2 degrees C. For the correct determination of external mixtures, it is necessary to take into account size-dependent losses due to diffusion in the plumbing between the DMAs and in the aerosol humidification unit.Peer reviewe

    Celebrating Cercignani's conjecture for the Boltzmann equation

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    Cercignani's conjecture assumes a linear inequality between the entropy and entropy production functionals for Boltzmann's nonlinear integral operator in rarefied gas dynamics. Related to the field of logarithmic Sobolev inequalities and spectral gap inequalities, this issue has been at the core of the renewal of the mathematical theory of convergence to thermodynamical equilibrium for rarefied gases over the past decade. In this review paper, we survey the various positive and negative results which were obtained since the conjecture was proposed in the 1980s.Comment: This paper is dedicated to the memory of the late Carlo Cercignani, powerful mind and great scientist, one of the founders of the modern theory of the Boltzmann equation. 24 pages. V2: correction of some typos and one ref. adde

    Decade-long profile of imaging biomarker use in ophthalmic clinical trials

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    PURPOSE. The purpose of this study was to investigate the use of imaging biomarkers in published clinical trials (CTs) in ophthalmology and its eventual changes during the past 10 years. METHODS. We sampled from published CTs in the fields of cornea, retina, and glaucoma between 2005\u20132006 and 2015\u20132016. Data collected included year of publication, phase, subspecialty, location, compliance with Consolidated Standards for Reporting Trials, impact factor, presence and use of imaging biomarkers (diagnostic, prognostic and predictive; primary and secondary surrogate endpoints), and use of centralized reading centers. RESULTS. We included 652 articles for analysis, equally distributed in three timeframes (2005\u2013 2006, 2010\u20132011, and 2015\u20132016), mainly reporting phase IV CTs and trials on procedures (42.2% and 35.4%, respectively). Imaging biomarkers were included in 46.3% of the analyzed CTs and their use significantly increased over time (P < 0.05). Optical coherence tomography was the most frequently used device (27.7%), whereas diagnostic biomarkers and secondary surrogate endpoints were the most frequent biomarker types (19.5% and 22.5%, respectively). Early-phase CTs showed an increase in the use of biomarkers for patient selection and stratification over time (P < 0.05), but not in the use of imaging surrogate endpoints (P = 0.90). Only 3 of 59 (5.1%) of phase III CTs included primary surrogate imaging endpoints, whereas secondary surrogate imaging endpoints were present in 50.8% of these trials (P < 0.001). Retinal CTs had the highest prevalence for each type of imaging biomarker (P < 0.001). Reading centers were used in 52 of 302 CTs (17.2%), with no significant time-related increase. CONCLUSIONS. Imaging biomarkers are increasingly used in published CTs in ophthalmology. Additional efforts, including centralized reading centers, are needed to improve their validation and use, allowing a wider use of these tools as primary surrogate endpoints in phase III CTs

    Complete characterization of convergence to equilibrium for an inelastic Kac model

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    Pulvirenti and Toscani introduced an equation which extends the Kac caricature of a Maxwellian gas to inelastic particles. We show that the probability distribution, solution of the relative Cauchy problem, converges weakly to a probability distribution if and only if the symmetrized initial distribution belongs to the standard domain of attraction of a symmetric stable law, whose index α\alpha is determined by the so-called degree of inelasticity, p>0p>0, of the particles: α=21+p\alpha=\frac{2}{1+p}. This result is then used: (1) To state that the class of all stationary solutions coincides with that of all symmetric stable laws with index α\alpha. (2) To determine the solution of a well-known stochastic functional equation in the absence of extra-conditions usually adopted

    2-D constrained Navier-Stokes equation and intermediate asymptotics

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    We introduce a modified version of the two-dimensional Navier-Stokes equation, preserving energy and momentum of inertia, which is motivated by the occurrence of different dissipation time scales and related to the gradient flow structure of the 2-D Navier-Stokes equation. The hope is to understand intermediate asymptotics. The analysis we present here is purely formal. A rigorous study of this equation will be done in a forthcoming paper

    Occurrence of the non-native species ophraella communa on ambrosia artemisiifolia in north-eastern italy, with records from slovenia and croatia

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    The ragweed leaf beetle, Ophraella communa LeSage (Coleoptera Chrysomelidae), is of North American origin and is associated with the Asteraceae, and especially with the invasive neophyte Ambrosia artemisiifolia L., which is native to North and Central America and currently naturalized in many parts of Europe, including Italy. The presence of the beetle in northern Italy and southern Switzerland was first noted in 2013. In 2017 it was first reported for Veneto region (north-eastern Italy) and Slovenia, and in 2018 for Croatia. An extensive survey was carried out in summer and autumn 2017 in Friuli Venezia Giulia, after the first accidental finding of some O. communa specimens on A. artemisiifolia plants at a site on the High Friulian Plain in July. To determine a possible pathway of O. communa entry, sites from the nearby eastern Veneto, western Slovenia and north-western Croatia were also inspected. O. communa was detected on A. artemisiifolia in 70 out of the 77 sampled sites in Friuli Venezia Giulia (54 sites), Veneto (5 sites), Slovenia (7 sites) and Croatia (4 sites). The distribution of O. communa on the Friulian and Veneto plains seems to be continuous. In 20% of cases, A. artemisiifolia defoliated plants or completely dried plants, lacking reproductive structures and with stem tissues seriously damaged were observed. In some cases, O. communa was found on other three Asteraceae, namely Xanthium orientale italicum (Moretti) Greuter, Erigeron canadensis (L.) Cronquist and Helianthus annuus L. The pathway of colonization by the beetle in the study area seems to be from west to east. These are the first records of the beetle for Friuli Venezia Giulia. The beetle seems to spread very rapidly across large areas and is very capable of effective control of the invasive weed, A. artemisiifolia
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