1,529 research outputs found

    Effectiveness of Flax-TRM composites under traction

    Get PDF
    The scientific research in the field of masonry structures is increasingly welcoming the adoption of innovative and sustainable rehabilitation techniques aimed at the safeguarding of the Built Cultural Heritage. Textile Reinforced Matrix (TRM) composites are the most widely investigated strengthening systems for ancient masonry structures, thanks to their high compatibility level with the material substrates in terms of fire resistance, chemical/physical aspects, reversibility property, little impact on dimensions, stiffness and weight. Nevertheless, in the last years, the growing concern on sustainability increased the interest in products with low environmental impact, for promoting circular economy approaches in the design of the structural interventions. In particular, efforts have been done to replace the most common composites with materials less harmful to the environment, such as natural fibres, for developing compatible and sustainable rehabilitation techniques for masonry structures. This paper presents the preliminary results of experimental tests conducted by the authors on specimens of TRM composites made with natural, vegetable, flax-fibre grids and natural hydraulic lime mortar. The mechanical characterization tests aimed at detecting the tensile behaviour of the natural TRM system compared to the results available in the literature on different vegetable-fibre composites and TRMs made with natural basalt fibres. The experimental tests highlighted the promising mechanical effectiveness of natural TRM systems under traction and offered a hint to further research aimed at improving their mechanical strength and stiffness

    Evolutionary Modeling to Evaluate the Shear Behavior of Circular Reinforced Concrete Columns

    Get PDF
    Despite their frequent occurrence in practice, only limited studies on the shear behavior of reinforced concrete (RC) circular members are available in the literature. Such studies are based on poor assumptions about the physical model, often resulting in being too conservative, as well as technical codes that essentially propose empirical conversion rules. On this topic in this paper, an evolutionary approach named EPR is used to create a structured polynomial model for predicting the shear strength of circular sections. The adopted technique is an evolutionary data mining methodology that generates a transparent and structured representation of the behavior of a system directly from experimental data. In this study experimental data of 61 RC circular columns, as reported in the technical literature, are used to develop the EPR models. As final result, physically consistent shear strength models for circular columns are obtained, to be used in different design situations. The proposed formulations are compared with models available from building codes and literature expressions, showing that EPR technique is capable of capturing and predicting the shear behavior of RC circular elements with very high accuracy. A parametric study is also carried out to evaluate the physical consistency of the proposed models

    Ruolo della timectomia nel trattamento della miastenia gravis: considerazioni e casistica personale

    Get PDF
    L’effetto terapeutico della timectomia sul decorso clinico della miastemia gravis è ancora quanto mai controverso. Infatti, mentre la chirurgia è ormai universalmente accettata per i timomi, il suo ruolo è ancora discutibile in pazienti con miastenia gravis. La via chirurgica di elezione per la timectomia totale è rappre - sentata dalla sternotomia mediana. Altre metodologie chirurgiche includono l’accesso cervicale e la sternotomia parziale. Queste tecni - che, seppure con alterne fortune, hanno mostrato risultati eccellenti nella exeresi del timo. Più recentemente la timectomia toracoscopica video-assistita è stata proposta come una tecnica meno invasiva e parimenti efficace per l’asportazione di quest’organo ed il trattamento della miastenia gravis. Scopo del presente lavoro è quello di riferire l’esperienza degli Autori in tema di timectomia, analizzando i dati riportati dalla lette - ratura internazionale sulla mortalità operatoria, le eventuali compli - canze e i risultati estetici delle diverse tipologie di accesso chirurgico

    Giant endobronchial hamartoma resected by fiberoptic bronchoscopy electrosurgical snaring

    Get PDF
    Less than 1% of lung neoplasms are represented by benign tumors. Among these, hamartomas are the most common with an incidence between 0.025% and 0.32%. In relation to the localization, hamartomas are divided into intraparenchymal and endobronchial

    Twenty‐four‐month real‐life treatment outcomes of polypoidal choroidal vasculopathy versus type 1 macular neovascularization in Caucasians

    Get PDF
    Background To compare 24‐month real‐world outcomes of Vascular Endothelial Growth Factor (VEGF) inhibitors for Polypoidal Choroidal Vasculopathy (PCV) and type 1 Macular Neovascularization (MNV) in a Caucasian population.MethodsRetrospective analysis from a prospectively designed observational database. Data from Italian centres participating in the Fight Retinal Blindness! (FRB!) project were collected. Treatment‐naïve PCV or type 1 MNV commencing treatment after January 2009 were included. The primary outcome was 24‐month visual acuity (VA) change; other outcomes included baseline characteristics, number of anti‐VEGF injections, time to lesion inactivation and proportion of active visits.ResultsA total of 322 eyes (114 PCVs) from 291 patients were included. Median [Q1, Q3] VA at baseline was comparable (70 [55, 75.8] vs. 70 [58.8, 75] letters, p = 0.95). Adjusted VA change at 2 years was higher in PCV (mean [95% CI], +1.2 [−1.6, 4.1] vs. −3.6 [−6, −1.2] letters, p = 0.005). PCV received fewer anti‐VEGF injections over the first 24 months of treatment than type 1 MNV (median [Q1, Q3], 8 [5, 10] vs. 9 [7, 12.2] injections, p = 0.001), inactivated earlier (median [Q1, Q3], 235 [184, 308] vs. 252 [169, 343] days, p = 0.04) and was less frequently graded ‘active’ (62% vs. 68% of visits, p = 0.001). Conclusions PCV had slightly better VA outcomes over 24 months of treatment than type 1 MNV after receiving less anti‐VEGF injections. These results suggest a possible overlap of the two clinical entities with similar visual prognosis in Caucasians

    A jeff=1/2j_\mathrm{eff} = 1/2 pseudospinon continuum in CaIrO3_3

    Full text link
    In so-called jeff=1/2j_\mathrm{eff} = 1/2 systems, including some iridates and ruthenates, the coherent superposition of t2gt_\mathrm{2g} orbitals in the ground state gives rise to hopping processes that strongly depend on the bond geometry. Resonant inelastic x-ray scattering (RIXS) measurements on CaIrO3_3 reveal a prototypical jeff=1/2j_\mathrm{eff} = 1/2 pseudospinon continuum, a hallmark of one-dimensional (1D) magnetic systems despite its three-dimensional crystal structure. The experimental spectra compare very well to the calculated magnetic dynamical structure factor of weakly coupled spin-1/2 chains. We attribute the onset of such quasi-1D magnetism to the fundamental difference in the magnetic interactions between the jeff=1/2j_\mathrm{eff} = 1/2 pseudospins along the corner- and edge-sharing bonds in CaIrO3_3.Comment: 8 pages, 4 figure

    Zero Fluoroscopy Arrhythmias Catheter Ablation: A Trend Toward More Frequent Practice in a High-Volume Center

    Get PDF
    BACKGROUND: Awareness of radiation exposure risks associated to interventional cardiology procedures is growing. The availability of new technologies in electrophysiology laboratories has reduced fluoroscopy usage during arrhythmias ablations. The aim of this study was to describe procedures with and without X-Rays and to assess feasibility, safety, and short-term efficacy of zero fluoroscopy intervention in a high-volume center oriented to keep exposure to ionizing radiation as low as reasonably achievable. METHODS: Cardiac catheter ablations performed in our hospital since January 2017 to June 2021. RESULTS: A total of 1,853 procedures were performed with 1,957 arrhythmias treated. Rate of fluoroless procedures was 15.4% (285 interventions) with an increasing trend from 8.5% in 2017 to 22.9% of first semester 2021. The most frequent arrhythmia treated was atrial fibrillation (646; 3.6% fluoroless) followed by atrioventricular nodal reentrant tachycardia (644; 16.9% fluoroless), atrial flutter (215; 8.8% fluoroless), ventricular tachycardia (178; 17.4% fluoroless), premature ventricular contraction (162; 48.1% fluoroless), and accessory pathways (112; 31.3% fluoroless). Although characteristics of patients and operative details were heterogeneous among treated arrhythmias, use of fluoroscopy did not influence procedure duration. Moreover, feasibility and efficacy were 100% in fluoroless ablations while the rate of major complications was very low and no different with or without fluoroscopy (0.45 vs. 0.35%). CONCLUSION: Limiting the use of X-Rays is necessary, especially when the available technologies allow a zero-use approach. A lower radiation exposure may be reached, reducing fluoroscopy usage whenever possible during cardiac ablation procedures with high safety, full feasibility, and efficacy

    Subretinal fluid may protect against macular atrophy in neovascular age‐related macular degeneration: 5 years of follow‐up from Fight Retinal Blindness registry

    Full text link
    PurposeThe purpose of the study was to assess the association of macular atrophy (MA) according to the activity of macular neovascularization (MNV) (inactive, only subretinal fluid [SRFL], or active, i.e. including intraretinal fluid [IRFL]) using optical coherence tomography (OCT) in patients with neovascular age‐related macular degeneration (nAMD).MethodsMulticentric observational study. Treatment‐naïve nAMD eyes without subfoveal MA or subretinal fibrosis (SF) at baseline were included since 1st January 2010 and 30th September 2016 to allow up to 5 years of treatment follow‐up. Eyes were grouped based on their predominant activity status as: (1) mostly inactive, (2) mostly active non‐SRFL only [IRFL] or (3) mostly active‐SRFL only [onlySRFL]. Kaplan–Meier survival curves estimated the time to development of MA or SF. Cox proportional hazards models evaluated predictors of developing subfoveal MA or SF. The main outcome measure was the risk of developing MA according to predominant MNV activity.ResultsA total of 973 eyes were eligible for analysis. OnlySRFL eyes had lower risk of developing subfoveal MA (HR [95% CI]: 0.56 [0.36, 0.88]; p = 0.024) and extrafoveal MA (HR [95% CI]: 0.41 [0.27, 0.61]; p < 0.001) than IRFL eyes. IRFL eyes had lower visual acuity (VA) (54.5 letters) and the highest proportion of eyes with vision ≤35 letters (25%) at 5 years while onlySRFL eyes had comparable 5‐year VA (63.7 letters) to inactive eyes (63.7 letters).ConclusionSubretinal fluid appears to protect against MA. Distinguishing the compartment of retinal fluid and understanding its relationship with MA and SF can guide the management of nAMD

    Brief communication: Co-seismic displacement on 26 and 30 October 2016 ( M w = 5.9 and 6.5) – earthquakes in central Italy from the analysis of a local GNSS network

    Get PDF
    Abstract. On 24 August 2016 a strong earthquake (Mw = 6.0) affected central Italy and an intense seismic sequence started. Field observations, DInSAR (Differential INterferometry Synthetic-Aperture Radar) analyses and preliminary focal mechanisms, as well as the distribution of aftershocks, suggested the reactivation of the northern sector of the Laga fault, the southern part of which was already rebooted during the 2009 L'Aquila sequence, and of the southern segment of the Mt Vettore fault system (MVFS). Based on this preliminary information and following the stress-triggering concept (Stein, 1999; Steacy et al., 2005), we tentatively identified a potential fault zone that is very vulnerable to future seismic events just north of the earlier epicentral area. Accordingly, we planned a local geodetic network consisting of five new GNSS (Global Navigation Satellite System) stations located a few kilometres away from both sides of the MVFS. This network was devoted to working out, at least partially but in some detail, the possible northward propagation of the crustal network ruptures. The building of the stations and a first set of measurements were carried out during a first campaign (30 September and 2 October 2016). On 26 October 2016, immediately north of the epicentral area of the 24 August event, another earthquake (Mw = 5.9) occurred, followed 4 days later (30 October) by the main shock (Mw = 6.5) of the whole 2016 summer–autumn seismic sequence. Our local geodetic network was fully affected by the new events and therefore we performed a second campaign soon after (11–13 November 2016). In this brief note, we provide the results of our geodetic measurements that registered the co-seismic and immediately post-seismic deformation of the two major October shocks, documenting in some detail the surface deformation close to the fault trace. We also compare our results with the available surface deformation field of the broader area, obtained on the basis of the DInSAR technique, and show an overall good fit
    • …
    corecore