finite element modelling tuned on experimental testing for the structural health assessment of an ancient masonry arch bridge

This paper presents the structural health assessment of a railway ancient masonry arch bridge located in Bologna, Italy. A three-dimensional finite element model of the entire bridge, tuned on in situ experimental tests, has been used for the assessment. In particular, the finite element model has been employed to evaluate the structural health of the bridge both in its actual state and in the hypothesis of a structural strengthening intervention

Modeling environmental ageing in masonry strengthened with composites

The effects of environmental ageing due to rising damp and salt crystallization on composite strengthening systems, e.g. fiber reinforced polymer (FRP) and fiber reinforced cementitious matrix (FRCM), bonded to masonry substrates are still scarcely known. Although few laboratory tests have been recently conducted to this aim, very limited information is available. In this paper, the simulation of accelerated weathering/ageing cycles of masonry strengthened with composites is proposed by means of a multiphase model which accounts for salt transport and crystallization. This multiphase model is implemented together with ad hoc boundary conditions and a restart analysis procedure which attempt to reproduce the repetition of weathering cycles (composed of a wetting phase in a saline solution and a drying phase in the oven). Laboratory accelerated weathering tests on masonry specimens strengthened with lime mortar-based FRCM are numerically reproduced. Additional information on the salt crystallization process within the specimen is obtained along with the weathering procedure. Further numerical insights are shown and compared for different strengthening systems, i.e. cement mortar-based FRCM and FRP. Different salt crystallization patterns in the specimens with different strengthening systems are observed and discussed

Numerical modelling-based damage diagnostics in cultural heritage structures

In this paper, a numerical modelling-based damage diagnostics methodology is proposed for cultural heritage structures (CHSs) made of masonry. Firstly, an integration of 3D documentation data (i.e. point clouds and virtual tours) is developed for the rapid numerical model generation of CHSs. This allows to directly exploit non-comprehensive point clouds (e.g., associated to outer surfaces only) for the solid finite element model generation, where the lacking information is merged with off-site interactive and immersive frameworks. Secondly, a number of nonlinear static and dynamic analyses are conducted on the generated solid model to account for various load scenarios (e.g., earthquakes, soil settlements, etc.), considering a nonlinear continuum constitutive law. Thirdly, a crack pattern matching indicator is introduced to quantitatively identify the most likely load scenario which originated the damage pattern present in the CHS, by comparing numerical and actual crack patterns. The proposed methodology allows to rapidly generate and extract the numerical model that reflects the current (damaged) state of the CHS. This also allows to identify the parts of the CHS susceptible to further damage. The effectiveness of the proposed methodology is promisingly assessed on an actual historical masonry structure, the Morris Island lighthouse in South Carolina (USA)

A Method for Battery Sizing in Parallel P4 Mild Hybrid Electric Vehicles

This article deals with a sensitivity analysis concerning the influence that the capacity of the battery in a parallel hybrid powertrain has on the vehicle's energy regeneration. The architecture under analysis is constituted by an internal combustion engine (ICE), which provides traction to the front axle's wheels, and an electric motor powering the rear wheels. The energy management system (EMS) is based on a simple torque split strategy that distributes the driver's required torque between the front and rear machines as a function of battery and electric motor functional limitations (state of charge, temperatures, and maximum admissible currents). Together with the selected driving cycles, the central role played by the battery size in the overall vehicle recoverable energy is evaluated, while the influence of the powertrain limitations is highlighted, accounting both for uncertain parameters (e.g., initial state of charge [SoC 0]) and for tunable parameters (e.g., maximum electric traction vehicle speed). Therefore, a method of sizing the battery of a P4 mild hybrid electric vehicle (HEV), which allows the maximization of the braking energy recovery, is developed

A computational multiscale approach to couple hygro-mechanical responses of large-scale masonry walls

We present a computational multiscale approach to the nonlinear problems of humidity diffusion and mechanical damage of large-scale masonry walls, and their coupling in terms of the effects of the humidity diffusion on the mechanical response and the effects of the mechanical degradation on the diffusion process. Such an approach allows us to recover, both efficiently and accurately, the complex nonlinear response of large-scale walls, which are in general hard to be solved by means of standard numerical tools. Two representative tests of two- and three-storey walls are here analyzed, and the corresponding results reported and commented, aiming to show how samples like these can potentially serve as reference solutions for more applicative purposes

A damaging block-based model for the analysis of the cyclic behaviour of full-scale masonry structures

In this paper, a damaging block-based model is proposed for the numerical analysis of the cyclic behaviour of full-scale masonry structures. Solid 3D finite elements governed by a plastic-damage constitutive law in tension and compression are used to model the blocks, while a cohesive-frictional contact-based formulation is developed to simulate their cyclic interaction. The use of tests on small-scale specimens to calibrate the mechanical properties of the numerical model is presented and discussed. The tests belong to a comprehensive experimental campaign performed on calcium silicate brick masonry. The calibrated models are used to simulate in-plane and out-of-plane cyclic tests on masonry walls made of the same material, as well as a quasi-static cyclic pushover test on a full-scale terraced masonry house. The efficiency, the potentialities and the accuracy of the model here proposed are shown and discussed. The capability of explicitly representing structural details (e.g. running bonds) and any in-plane and through-thickness texture of masonry, which appears essential to study the response of masonry structures, is guaranteed by the block-based modelling approach. A good agreement between the numerical results and the experimental outcomes is observed. This allows to validate the model in the cyclic response as well as the strategy proposed for its mechanical characterization

Students’ experiences of learning in the operating theatre

Human parechoviruses (HPeVs) are members of the large and growing family of Picornaviridae. Although 16 types have been described on the basis of the phylogenetic analyses of the VP1 encoding region, the majority of published reports relate to the HPeV types 1-8. In pediatrics, HPeV1, HPeV2 and HPeV4-8 mainly cause mild gastrointestinal or respiratory illness; only occasionally more serious diseases have been reported, including myocarditis, encephalitis, pneumonia, meningitis, flaccid paralysis, Reye syndrome and fatal neonatal infection. In contrast, HPeV3 causes severe illness in young infants, including sepsis and conditions involving the central nervous system. Currently, the most sensitive method for detecting HPeV is real-time polymerase chain reaction assays on stools, respiratory swabs, blood and cerebrospinal fluid. However, although it is known that HPeVs play a significant role in various severe pediatric infectious diseases, diagnostic assays are not routinely available in clinical practice and the involvement of HPeV is therefore substantially underestimated. Despite long-term efforts, the development of antiviral therapy against HPeVs is limited; no antiviral medication is available and the use of monoclonal antibodies is still being evaluated. More research is therefore needed to clarify the specific characteristics of this relevant group of viruses and to develop appropriate treatment strategies

Update on the management of pediatric acute osteomyelitis and septic arthritis

Acute osteomyelitis and septic arthritis are two infections whose frequencies are increasing in pediatric patients. Acute osteomyelitis and septic arthritis need to be carefully assessed, diagnosed, and treated to avoid devastating sequelae. Traditionally, the treatment of acute osteoarticular infection in pediatrics was based on prolonged intravenous anti-infective therapy. However, results from clinical trials have suggested that in uncomplicated cases, a short course of a few days of parenteral antibiotics followed by oral therapy is safe and effective. The aim of this review is to provide clinicians an update on recent controversies and advances regarding the management of acute osteomyelitis and septic arthritis in children. In recent years, the emergence of bacterial species resistant to commonly used antibiotics that are particularly aggressive highlights the necessity for further research to optimize treatment approaches and to develop new molecules able to fight the war against acute osteoarticular infection in pediatric patients

Effect of a multistrain probiotic (Lactoflorene® Plus) on inflammatory parameters and microbiota composition in subjects with stress-related symptoms

Stress affects the immune system and intestinal microbiota composition and can lead to imbalance between pro- and anti-inflammatory cytokines or to uncontrolled production of cytokines. The effect of emotional stress on secretory IgA levels also indicates that stress decreases mucosal integrity. Our aim was to evaluate whether a probiotic product (Lactoflorene® Plus) can prevent alterations in the immune response associated with self-reported stress and microbiota composition. Healthy adult volunteers who self-reported psychological stress were enrolled and randomised into a placebo and a probiotic group. Salivary stress markers (α-amylase, cortisol, chromogranin A) and immunological parameters (sIgA, NK cell activity, IL-8, IL-10, TNF-α) in feces and the composition of intestinal microbiota were evaluated. Administration of the product did not exert a direct effect on the salivary stress markers or NK cell activity but did reduce abdominal pain and increase faecal IgA and IL-10 levels. The probiotic product induced a moderate increase in Bifidobacterium and Lactobacillus spp., as expected, and in Faecalibacterium spp., and decreased the size of the Dialister spp. and Escherichia and Shigella populations. Administration of the product helped protect the mucosal barrier by supporting the number of short-chain fatty acid producers and decreasing the load of potentially harmful bacteria, thus reducing intestinal inflammation and abdominal discomfort. ClinicalTrials.gov: NCT03234452

Listeria monocytogenes meningitis in immunocompetent and healthy children: a case report and a review of the literature

BackgroundListeria monocytogenes is a gram-positive bacteria generally transmitted to humans through ingestion of contaminated food. It typically infects high risk subjects, such as pregnant women, neonates, the elderly and immunocompromised patients. Listeria meningitis is rarely reported in previously healthy children with no immunological disorders. However, it can be aggressive in such subjects and is associated with a high mortality rate. Prompt diagnosis is essential so that adequate antibiotic treatment can be started and the best outcome achieved.Case presentationWe report the case of a previously healthy 16-month-old child with Listeria meningitis who was successfully treated with intravenous ampicillin and gentamicin without any sequelae.ConclusionsAlthough Listeria meningitis is rare in previously healthy immunocompetent children, it must be considered, especially in children who do not improve with first-line antibiotic treatment. A review of the literature published since 1996 has been performed, to provide a general overview on this topic