Collegamenti di elementi prefabbricati in C.A.P. in zona sismica

Il presente lavoro ha come oggetto la caratterizzazione sperimentale del comportamento meccanico in campo sismico di un particolare tipo di connessione a secco in uso nei collegamenti tra elementi di piano e travi portanti di strutture prefabbricate in C.A. Il sistema di fissaggio in esame è realizzato con connettori a piastra angolare, anche chiamati a squadretta, e il sistema di piano che fa uso di tali connessioni è quello costituito da elementi a doppio T (detti a p greco), elementi nervati più utilizzati nella realizzazione di coperture piane e solai in strutture prefabbricate in C.A. Lo studio è stato sviluppato nell’ambito di un programma di ricerca finanziato dall’Associazione italiana dell’industria di prefabbricazione Assobeton, che si svolge sotto il coordinamento del Politecnico di Milano, in collaborazione con le Università di Pisa, di Firenze, di Bergamo, di Bologna, di Molise e di Napoli. Tale programma di ricerca è finalizzato allo studio del comportamento dei nodi e delle unioni, realizzate prevalentemente a secco, nelle strutture prefabbricate in ambito sismico, con l’obbiettivo di dare risposta alla necessità ampiamente sentita di una soluzione scientificamente completa circa i problemi della loro progettazione, in osservanza dei criteri di duttilità e di gerarchia delle resistenze che le moderne norme sismiche sistematicamente adottano. In applicazione dei risultati dell’analisi sperimentale, si è compiuta un’analisi numerica di un edificio tipo realizzato con l’impiego del collegamento in esame, che ha dimostrato l’inadeguatezza, in campo sismico, della modellazione usuale di tali connessioni

Dealing with COVID-19 stressful events, stress and anxiety: the mediating role of emotion regulation strategies in Italian women

Background This study aims to better understand the causal relationship between COVID-19 stressful events, perceived stress, emotion regulation strategies and anxiety symptoms in Italian women. Specifically, we assumed that: (i) different COVID-19 stressful events can directly or indirectly influence the manifestation of anxiety symptoms; (ii) perceived stress and emotion regulation strategies can mediate the relationship between COVID-19 stressful events and anxiety symptoms. Participants and procedure An online survey was distributed during the Italian mandatory lockdown – between 18th and 28th April 2020 – across the national territory. The final sample was composed of 1132 women living in different Italian regions (North 63.30%, Centre 14.20%, South 18.50%, Islands 4.00%) with a mean age of 40.19 years, ranging from 19 to 83 years (SD = 12.87). Participants filled out the Perceived Stress Scale (PSS-10), Spielberger State-Trait Anxiety Inventory (STAI) X1/R, Emotion Regulation Questionnaire (ERQ-10), five dichotomous questions assessing the COVID-19 stressful events and a demographic form. Pearson correlation analyses were performed to examine whether associations between factors conformed to the prerequisites for path analysis. Path analysis was conducted to test the model. Results “Having contracted the flu during the COVID-19 pandemic” and “having a family member infected by COVID-19” have a direct effect on the level of perceived stress and an indirect effect on the manifestation of anxiety symptoms. Finally, we found that emotion regulation strategies mediate the relationship between perceived stress and state anxiety symptoms. Conclusions Our results allow one to select the stressful events to which, in the pandemic era, it is necessary to pay particular attention in a clinical setting and suggest the implementation of psychological interventions that make emotion regulation an essential direct target of treatment in chronic stress-related pathology such as anxiety disorders.Background This study aims to better understand the causal relationship between COVID-19 stressful events, perceived stress, emotion regulation strategies and anxiety symptoms in Italian women. Specifically, we assumed that: (i) different COVID-19 stressful events can directly or indirectly influence the manifestation of anxiety symptoms; (ii) perceived stress and emotion regulation strategies can mediate the relationship between COVID-19 stressful events and anxiety symptoms. Participants and procedure An online survey was distributed during the Italian mandatory lockdown – between 18th and 28th April 2020 – across the national territory. The final sample was composed of 1132 women living in different Italian regions (North 63.30%, Centre 14.20%, South 18.50%, Islands 4.00%) with a mean age of 40.19 years, ranging from 19 to 83 years (SD = 12.87). Participants filled out the Perceived Stress Scale (PSS-10), Spielberger State-Trait Anxiety Inventory (STAI) X1/R, Emotion Regulation Questionnaire (ERQ-10), five dichotomous questions assessing the COVID-19 stressful events and a demographic form. Pearson correlation analyses were performed to examine whether associations between factors conformed to the prerequisites for path analysis. Path analysis was conducted to test the model. Results “Having contracted the flu during the COVID-19 pandemic” and “having a family member infected by COVID-19” have a direct effect on the level of perceived stress and an indirect effect on the manifestation of anxiety symptoms. Finally, we found that emotion regulation strategies mediate the relationship between perceived stress and state anxiety symptoms. Conclusions Our results allow one to select the stressful events to which, in the pandemic era, it is necessary to pay particular attention in a clinical setting and suggest the implementation of psychological interventions that make emotion regulation an essential direct target of treatment in chronic stress-related pathology such as anxiety disorders

Fire Characterization by Using an Original RST-Based Approach for Fire Radiative Power (FRP) Computation

Fire radiative power (FRP) is a basic parameter for fire characterization since it represents the heat emission rate of fires. Moreover, its temporal integration (fire radiative energy, FRE) is used as a proxy for estimating biomass burning and emissions. From satellite, FRP is generally computed by comparing the Medium InfraRed (MIR) signal of the fire pixel with the background value on the event image. Such an approach is possibly affected by some issues due to fire extent, clouds and smoke over the event area. The enlargement of the background window is the commonly used gimmick to face these issues. However, it may include unrepresentative signals of the fire pixel because of very different land use/cover. In this paper, the alternative Background Radiance Estimator by a Multi-temporal Approach (BREMA), based on the Robust Satellite Technique (RST), is proposed to characterize background and compute FRP. The approach is presented using data from the Spinning Enhanced Visible and InfraRed Imager (SEVIRI) onboard the Meteosat Second Generation (MSG) platform. Moreover, BREMA is here combined with the RST-FIRES (RST for FIRES detection) technique for fire pixel identification and the -SEVIRI retrieval algorithm for transmittance evaluation. Results compared to the operational SEVIRI-based FRP-PIXEL product, although highly correlated in terms of background radiance (r2=0.95) and FRP values (r2=0.96), demonstrated a major capability of BREMA to estimate background radiances regardless of cloudiness or smoke presence during the event and independently on fire extent. The possible impact of the proposed approach on the estimates of CO2 emissions was also evaluated for comparison with the Global Fire Emissions Database (GFED4s)

Mt. Etna Paroxysms of February–April 2021 Monitored and Quantified through a Multi-Platform Satellite Observing System

On 16 February 2021, an eruptive paroxysm took place at Mt. Etna (Sicily, Italy), after continuous Strombolian activity recorded at summit craters, which intensified in December 2020. This was the first of 17 short, but violent, eruptive events occurring during February–April 2021, mostly at a time interval of about 2–3 days between each other. The paroxysms produced lava fountains (up to 1000 m high), huge tephra columns (up to 10–11 km above sea level), lava and pyroclastic flows, expanding 2–4 km towards East and South. The last event, which was characterised by about 3 days of almost continuous eruptive activity (30 March–1 April), generated the most lasting lava fountain (8–9 h). During some paroxysms, volcanic ash led to the temporary closure of the Vincenzo Bellini Catania International Airport. Heavy ash falls then affected the areas surrounding the volcano, in some cases reaching zones located hundreds of kilometres away from the eruptive vent. In this study, we investigate the Mt. Etna paroxysms mentioned above through a multi-platform satellite system. Results retrieved from Advanced Very High Resolution Radiometer (AVHRR), Moderate Resolution Imaging Spectroradiometer (MODIS), and Spinning Enhanced Visible and Infrared Imager (SEVIRI), starting from outputs of the Robust Satellite Techniques for Volcanoes (RSTVOLC), indicate that the 17th paroxysm (31 March–1 April) was the most powerful, with values of radiative power estimated around 14 GW. Moreover, by the analysis of SEVIRI data, we found that the 5th and 17th paroxysms were the most energetic. The Multispectral Instrument (MSI) and the Operational Land Imager (OLI), providing shortwave infrared (SWIR) data at 20/30 m spatial resolution, enabled an accurate localisation of active vents and the mapping of the areas inundated by lava flows. In addition, according to the Normalized Hotspot Indices (NHI) tool, the 1st and 3rd paroxysm (18 and 28 February) generated the largest thermal anomaly at Mt. Etna after June 2013, when Landsat-8 OLI data became available. Despite the impact of clouds/plumes, pixel saturation, and other factors (e.g., satellite viewing geometry) on thermal anomaly identification, the used multi-sensor approach allowed us to retrieve quantitative information about the 17 paroxysms occurring at Mt. Etna. This approach could support scientists in better interpreting changes in thermal activity, which could lead to future and more dangerous eruptions

Reconstruction of primary vertices at the ATLAS experiment in Run 1 proton–proton collisions at the LHC

This paper presents the method and performance of primary vertex reconstruction in proton–proton collision data recorded by the ATLAS experiment during Run 1 of the LHC. The studies presented focus on data taken during 2012 at a centre-of-mass energy of √s=8 TeV. The performance has been measured as a function of the number of interactions per bunch crossing over a wide range, from one to seventy. The measurement of the position and size of the luminous region and its use as a constraint to improve the primary vertex resolution are discussed. A longitudinal vertex position resolution of about 30μm is achieved for events with high multiplicity of reconstructed tracks. The transverse position resolution is better than 20μm and is dominated by the precision on the size of the luminous region. An analytical model is proposed to describe the primary vertex reconstruction efficiency as a function of the number of interactions per bunch crossing and of the longitudinal size of the luminous region. Agreement between the data and the predictions of this model is better than 3% up to seventy interactions per bunch crossing

Search for massive, long-lived particles using multitrack displaced vertices or displaced lepton pairs in pp collisions at √s = 8 TeV with the ATLAS detector

Many extensions of the Standard Model posit the existence of heavy particles with long lifetimes. This article presents the results of a search for events containing at least one long-lived particle that decays at a significant distance from its production point into two leptons or into five or more charged particles. This analysis uses a data sample of proton-proton collisions at √s=8  TeV corresponding to an integrated luminosity of 20.3  fb−1 collected in 2012 by the ATLAS detector operating at the Large Hadron Collider. No events are observed in any of the signal regions, and limits are set on model parameters within supersymmetric scenarios involving R-parity violation, split supersymmetry, and gauge mediation. In some of the search channels, the trigger and search strategy are based only on the decay products of individual long-lived particles, irrespective of the rest of the event. In these cases, the provided limits can easily be reinterpreted in different scenarios

Observation of the γγ→ττ process in Pb+Pb collisions and constraints on the τ-lepton anomalous magnetic moment with the ATLAS detector

This Letter reports the observation of τ-lepton-pair production in ultraperipheral lead-lead collisions Pb+Pb→Pb(γγ→ττ)Pb and constraints on the τ-lepton anomalous magnetic moment a_{τ}. The dataset corresponds to an integrated luminosity of 1.44 nb^{-1} of LHC Pb+Pb collisions at sqrt[s_{NN}]=5.02 TeV recorded by the ATLAS experiment in 2018. Selected events contain one muon from a τ-lepton decay, an electron or charged-particle track(s) from the other τ-lepton decay, little additional central-detector activity, and no forward neutrons. The γγ→ττ process is observed in Pb+Pb collisions with a significance exceeding 5 standard deviations and a signal strength of μ_{ττ}=1.03_{-0.05}^{+0.06} assuming the standard model value for a_{τ}. To measure a_{τ}, a template fit to the muon transverse-momentum distribution from τ-lepton candidates is performed, using a dimuon (γγ→μμ) control sample to constrain systematic uncertainties. The observed 95% confidence-level interval for a_{τ} is -0.057<0.024

Measurements of W+W- production in decay topologies inspired by searches for electroweak supersymmetry

This paper presents a measurement of fiducial and differential cross-sections for W+W- production in proton–proton collisions at s=13 TeV with the ATLAS experiment at the Large Hadron Collider using a dataset corresponding to an integrated luminosity of 139 fb - 1 . Events with exactly one electron, one muon and no hadronic jets are studied. The fiducial region in which the measurements are performed is inspired by searches for the electroweak production of supersymmetric charginos decaying to two-lepton final states. The selected events have moderate values of missing transverse momentum and the ‘stransverse mass’ variable mT2 , which is widely used in searches for supersymmetry at the LHC. The ranges of these variables are chosen so that the acceptance is enhanced for direct W+W- production and suppressed for production via top quarks, which is treated as a background. The fiducial cross-section and particle-level differential cross-sections for six variables are measured and compared with two theoretical SM predictions from perturbative QCD calculations