Communities in high definition : Spatial and environmental factors shape the micro-distribution of aquatic invertebrates

According to metacommunity theories, the structure of natural communities is the result of both environmental filtering and spatial processes, with their relative importance depending on factors including local habitat characteristics, functional features of organisms, and the spatial scale considered. However, few studies have explored environmental and spatial processes in riverine systems at local scales, explicitly incorporating spatial coordinates into multi-taxa distribution models. To address this gap, we conducted a small-scale study to discriminate between abiotic and biotic factors affecting the distribution of aquatic macroinvertebrates, applying metacommunity concepts. We studied a mountain section in each of three perennial streams within the Po River Basin (northern Italy). We sampled macroinvertebrates both in summer and winter, using specific in situ 50-point random sampling grids. Environmental factors, including benthic organic matter (BOM), flow velocity, water depth, and substrate were recorded together with spatial coordinates for each sampling point. The relationships between community metrics (taxon richness, abundance, biomass, biomass-abundance ratio, and functional feeding groups) and explanatory variables (environmental and spatial) were assessed using generalised additive models. The influence of the explanatory variables on community structure was analysed with joint species distribution models. Environmental variables-primarily BOM-were the main drivers affecting community metrics, whereas the effects of spatial variables varied among metrics, streams, and seasons. During summer, community structure was strongly affected by BOM and spatial position within the riverbed, the latter probably being a proxy for mass effects mediated by biotic and stochastic processes. In contrast, community structure was mainly shaped by hydraulic variables in winter. Using macroinvertebrate communities as a model group, our results demonstrate that metacommunity concepts can explain small-scale variability in community structure. We found that both environmental filtering and biotic processes shape local communities, with the strength of these drivers depending on the season. These insights provide baseline knowledge that informs our understanding of ecological responses to environmental variability in contexts including restoration ecology, habitat suitability modelling, and biomonitoring.Peer reviewe

LFR safety approach and main ELFR safety analysis results

This paper summarizes the approach to safety for the LFR systems, developed on the basis of the recommendations of the Generation IV International Forum (GIF) Risk and Safety Working Group (RSWG) and taking into account the fundamental safety objectives and the Defence-in-Depth approach, as described by IAEA Safety Guides, as well as the Safety quantitative objectives reported in the European Utilities Requirements (EUR). LEADER project activities are focused on the resolution of the key issues as they emerged from the 6th FP ELSY project attempting to reach a new industrial size European Lead-cooled Fast Reactor (ELFR) configuration. Apart from the safety approach, the main results of the ELFR safety transient analysis, where the most important design basis condition (DBC) and design extension condition (DEC) transient initiators were re-analyzed using the system codes RELAP5 (ENEA), TRACE-FRED (PSI), SIM-LFR (KIT) and SIMMER (CIRTEN), are summarized

Identification and categorisation of safety issues for ESNII reactor concepts. Part I: Common phenomena related to materials

International audience; With the aim to develop a joint proposal for a harmonised European methodology for safety assessment of advanced reactors with fast neutron spectrum, SARGEN-IV (Safety Assessment for Reactors of Gen IV) Euratom coordination action project gathered together twenty-two partners' safety experts from twelve EU Member States. The group consisted of eight European Technical Safety Organisations involved in the European Technical Safety Organisation Network (ETSON), European Commission's Joint Research Centre (JRC), system designers, industrial vendors as well as research and development (RandD) organisations. To support the methodology development, key safety features of four fast neutron spectrum reactor concepts considered in Deployment Strategy of the Sustainable Nuclear Energy Technology Platform (SNETP) were reviewed. In particular, outcomes from running European Sustainable Nuclear Industrial Initiative (ESNII) system projects and related Euratom collaborative projects for Sodium-cooled Fast Reactors, Lead-cooled Fast Reactors, Gas-cooled Fast Reactors, and the lead-bismuth eutectic cooled Fast Spectrum Transmutation Experimental Facility were gathered and critically assessed. To allow a consistent build-up of safety architecture for the ESNII reactor concepts, the safety issues were further categorised to identify common phenomena related to materials. Outcomes of the present work also provided guidance for the identification and prioritisation of further RandD needs respective to the identified safety issues. © 2015 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-NDlicense

Ventilatory associated barotrauma in COVID-19 patients: A multicenter observational case control study (COVI-MIX-study)

Background: The risk of barotrauma associated with different types of ventilatory support is unclear in COVID-19 patients. The primary aim of this study was to evaluate the effect of the different respiratory support strategies on barotrauma occurrence; we also sought to determine the frequency of barotrauma and the clinical characteristics of the patients who experienced this complication. Methods: This multicentre retrospective case-control study from 1 March 2020 to 28 February 2021 included COVID-19 patients who experienced barotrauma during hospital stay. They were matched with controls in a 1:1 ratio for the same admission period in the same ward of treatment. Univariable and multivariable logistic regression (OR) were performed to explore which factors were associated with barotrauma and in-hospital death. Results: We included 200 cases and 200 controls. Invasive mechanical ventilation was used in 39.3% of patients in the barotrauma group, and in 20.1% of controls (p<0.001). Receiving non-invasive ventilation (C-PAP/PSV) instead of conventional oxygen therapy (COT) increased the risk of barotrauma (OR 5.04, 95% CI 2.30 - 11.08, p<0.001), similarly for invasive mechanical ventilation (OR 6.24, 95% CI 2.86-13.60, p<0.001). High Flow Nasal Oxygen (HFNO), compared with COT, did not significantly increase the risk of barotrauma. Barotrauma frequency occurred in 1.00% [95% CI 0.88-1.16] of patients; these were older (p=0.022) and more frequently immunosuppressed (p=0.013). Barotrauma was shown to be an independent risk for death (OR 5.32, 95% CI 2.82-10.03, p<0.001). Conclusions: C-PAP/PSV compared with COT or HFNO increased the risk of barotrauma; otherwise HFNO did not. Barotrauma was recorded in 1.00% of patients, affecting mainly patients with more severe COVID-19 disease. Barotrauma was independently associated with mortality. Trial registration: this case-control study was prospectively registered in clinicaltrial.gov as NCT04897152 (on 21 May 2021)

External Event Risk Assessment: Methodology and Application

This study is therefore aimed at the evaluation of the NPP safety performance when subjected to external events, such as the earthquake and/or tsunami (inundation phase), by applying the IDPSA (Integrated Deterministic Probabilistic Safety Analysis) approach, which combines the Probabilistic and Deterministic Safety Assessment ones. To the purpose “stress tests” suggestions, presently foreseen by the European and International Associations, have been taken into account. The main issues as emerging from the Fukushima accident, specifically the LOOP/SBO (Loss Of Offsite Power/Station Black Out) caused by a flooding or tsunami, were analysed. The results indicated that although the containment building is suffering local damaging, no loss of structural integrity occurs

Reliability assessment of passive safety systems for nuclear energy applications: State‐of‐the‐art and open issues

Passive systems are fundamental for the safe development of Nuclear Power Plant (NPP) technology. The accurate assessment of their reliability is crucial for their use in the nuclear industry. In this paper, we present a review of the approaches and procedures for the reliability assessment of passive systems. We complete the work by discussing the pending open issues, in particular with respect to the need of novel sensitivity analysis methods, the role of empirical modelling and the integration of passive safety systems assessment in the (static/dynamic) Probabilistic Safety Assessment (PSA) framework

L&#8217;infanticidio a Milano tra 1862 e 1930 : analisi di 65 dispositivi di sentenza

Gli Autori affrontano il tema del reato di infanticidio nel periodo storico compreso tra l\u2019unit\ue0 d\u2019Italia e l\u2019emanazione del Codice Rocco (1930), con particolare riferimento al territorio milanese. Introdotta l\u2019evoluzione della normativa vigente in Italia dopo il 1861 e riportate le statistiche giudiziarie nazionali circa il reato di infanticidio tra XIX e XX secolo, si procede con l\u2019analisi dettagliata di 65 dispositivi di sentenza della Corte d\u2019Assise di Milano e di Busto Arsizio conservati presso l\u2019Archivio di Stato di Milano in volumi suddivisi per anno, i quali sono stati fotografati e quindi studiati direttamente dal supporto digitale. Dai dati ricavati, si traccia quindi un quadro della situazione milanese caratterizzando l\u2019infanticidio e ponendo particolare attenzione all\u2019autore del reato, alla distribuzione nel territorio, alla modalit\ue0 lesiva impiegata, alle pene comminateAuthors study infanticide during the age between the unification of Italy and the issue of Codice Rocco (1930), in particular around Milan. They introduce the evolution of Italian laws after 1861 and quote national legal statistics about infanticide between XIX and XX century; they particularly analyze 65 executive judgements pronounced by Corte d\u2019Assise in Milan and Busto Arsizio that are kept in Archivio di Stato in Milan in volumes divided into years, and that were photographed and studied on digital images. From data, authors drawn the situation in Milan characterizing infanticide and pointing on the author of the crime, the distribution in the country, the kind of injuries, the length of punishments

Innovative engineering safeguards to cope with corium relocation: Identification of loads and failure modes

The proposed study deals with the assessment of passive systems, implemented in reactor designs to extend the coping period in the event of adverse situations, involving the melting of the core, such as occurred at the Fukushima Daiichi plant. To the aim, the feasibility of a new in-vessel core melt retention (IVCR) strategy is investigated. This strategy is based on an original design of a core catcher made of batch of ceramic multi-layered pebble that, by profiting of the low thermal conductivity, is capable to retard the heat-up of the lower head of the vessel during the relocation of the corium (recognized as the “Achilles-heel” of the Gen. II or earlier PWR designs). The arrest of heat-up and eventual quenching is indeed the key to the survival of the RPV as the significant thermal and pressure loadings may cause a reduction of mechanical strength of the vessel, and even its failure. In doing that, issues evolving and caused by the corium relocation are investigated both analytically and numerically. Thermo-mechanical analyses are performed by means of FEM code, assuming firstly homogeneous pool condition. The heat transport to the hemispherical boundary is simulated through conduction, and, then, through a boundary layer created by the downward flow along the curved wall from the upper part of the pool. Results show that the heat-up of the vessel wall, in the long time period, may cause a thermal degradation of the vessel strength. Nevertheless, the adoption of the proposed core catcher solution extends the coping period: after 1 hr from the event initiating the maximum temperature reached by the vessel wall is below the allowed limit for which localized failure may appear

The REPAS approach to the evaluation of passive safety system reliability

Scope of this research, carried out by ENEA in collaboration with University of Pisa and Polytechnic of Milano since 1999, is the identification of a methodology allowing the evaluation of the reliability of passive systems as a whole, in a more physical and phenomenal way. The paper describe the study, named REPAS (Reliability Evaluation of Passive Safety systems), carried out by the partners and finalised to the development and validation of such a procedure. The strategy of engagement moves from the consideration that a passive system should be theoretically more reliable than an active one. In fact it does not need any external input or energy to operate and it relies only upon natural physical laws (e.g. gravity, natural circulation, internally stored energy, etc.) and/or “intelligent” use of the energy inherently available in the system (e.g. chemical reaction, decay heat, etc.). Nevertheless the passive system may fail its mission not only as a consequence of classical mechanical failure of components, but also for deviation from the expected behaviour, due to physical phenomena mainly related to thermalhydraulics or due to different boundary and initial conditions. The main sources of physical failure are identified and a probability of occurrence is assigned. The reliability analysis is performed on a passive system which operates in two-phase, natural circulation. The selected system is a loop including a heat source and a heat sink where the condensation occurs. The system behaviour under different configurations has been simulated via best-estimate code (Relap5 mod3.2). The results are shown and can be treated in such a way to give qualitative and quantitative information on the system reliability. Main routes of development of the methodology are also depicted