Health monitoring of composite structures via MEMS sensor networks: numerical and experimental results

Laminated composites often develop hidden damages, e.g., delamination. [...

A multiscale approach to the smart deployment of micro-sensors over flexible plates

In former studies, we proposed a topology optimization approach to maximize the sensitivity to damage of measurements collected through a network of sensors deployed over flexible, thin plates. Within such frame, damage must be intended as a change of the structural health characterized by a reduction of the relevant load-carrying capacity. By properly comparing the response of the healthy, undamaged structure and the response of the damaged one, independently of the location of the source of damage, a procedure to optimally deploy a given set of sensors was provided. In this work we extend the aforementioned approach within a multiscale frame, to account for (at least) three different length-scales: a macroscopic one, linked to the dimensions of the structure to be monitored; a mesoscopic one, linked to the characteristic size of the damaged region(s); a microscopic one, linked to the size of inertial microelectromechanical systems (MEMS) to be used within a marginally invasive health monitoring system. Results are provided for a square plate fully clamped along its border, to show how the micro-sensors are to be deployed to maximize the sensitivity of measurements to damage, and to also discuss the speedup obtained with the proposed multiscale approach in comparison with a standard single-scale one

Modelling mixed-mode fracture in poly(methylmethacrylate) using peridynamics

AbstractPeridynamics (Silling (2000)) is a non-local continuum theory that is particularly suited to handle discontinuities in the displacement field, such as those arising during fracture. Peridynamics prescribes that each material point interacts with all its neighbors contained in a sphere of given radius; this assumption introduces a characteristic length scale in the continuum description. In a nutshell, the interactions between material points depend on their relative distance; in the peridynamics framework this distance is called the “bond length”. The equations of motion, holding at each material point, link the material point acceleration to the integral over the point neighborhood of a force density field, whose strength depend on bond-stretches, i.e. the ratio of the actual bond-length over the initial one. In these equations the displacement gradient does not appear, thus naturally allowing for discontinuities in the displacement field to occur. As to failure, the simplest possible damage description is provided by an interaction law prescribing the force to vanish when a critical bond-stretch threshold is crossed; this parameter can be related to the Mode I critical strain energy release rate. A single parameter is needed to describe failure, in principle under every possible loading condition.In this work the predictive abilities of peridynamics were checked against experimental results in the case of mixed-mode failure of brittle polymers. Pre-cracked poly(methylmethacrylate) (PMMA) samples were tested using different specimens, in order to obtain Mode I, Mixed-Mode and Mode II loading conditions. The material was assumed to behave according to a peridynamics brittle elastic material model; the parameters needed to calibrate the elastic behavior were determined from Mode I tests, as was the critical stretch.The peridynamics simulations of mixed-mode tests were able to catch the correct fracture initiation load and to provide a fair description of the crack path under different conditions. The peridynamics model was also able to qualitatively capture the typical “nail” shape assumed by the crack front during propagation

SIAIP position paper: provocation challenge to antibiotics and non-steroidal anti-inflammatory drugs in children

Drug hypersensitivity reactions (DHRs) in childhood are mainly caused by betalactam or non-betalactam antibiotics, and non-steroidal anti-inflammatory drugs (NSAIDs). Laboratory tests for identifying children who are allergic to drugs have low diagnostic accuracy and predictive value. The gold standard to diagnose DHR is represented by the drug provocation test (DPT), that aims of ascertaining the causative role of an allergen and evaluating the tolerance to the suspected drug. Different protocols through the administration of divided increasing doses have been postulated according to the type of drug and the onset of the reaction (immediate or non immediate reactions). DPT protocols differ in doses and time interval between doses. In this position paper, the Italian Pediatric Society for Allergy and Immunology provides a practical guide for provocation test to antibiotics and NSAIDs in children and adolescents

Smart sensing of damage in flexible plates through MEMS

In this work, we present a methodology to monitor the state of damage- or crack-containing flexible plates through low-cost, commercial off-the-shelf MEMS accelerometers. Under quasi-static, time-varying loading conditions we track the evolution of the damaged zone (e.g., the length of an inner crack) accounting for the drift in the compliance of the specimens, measured by means of the magnitude of the load-induced rotation at MEMS position. We then validate this health monitoring methodology, showing that it turns out to be sensitive to the damage and provides results in good accordance with theoretical findings. Next, we propose a technique to optimally deploy the MEMS sensors over the plate. Referring to an isotropic square plate containing damaged zones of reduced bending stiffness, we numerically investigate the sensitivity of the load-induced state (in terms of out-of-plane displacement and rotation of the normal to the mid-plane) to the position of the damaged area, and we adopt a constrained topology optimisation tool to determine the best sensor deployment to efficiently sense the damage

Correction to: Bone metabolism in patients with anorexia nervosa and amenorrhoea.

Unfortunately, the sixth author name was incorrectly spelled as "S. Fassio" instead of "A. Fassio" in the original publication

Consensus communication strategies to improve doctor-patient relationship in paediatric severe asthma

Background: Asthma is a chronic inflammatory disease that is very common among youth worldwide. The burden of this illness is very high not only considering financial costs but also on emotional and social functioning. Guidelines and many researches recommend to develop a good communication between physicians and children/caregiver and their parents. Nevertheless, a previous Italian project showed some criticalities in paediatric severe asthma management. The consensus gathered together experts in paediatric asthma management, experts in narrative medicine and patient associations with the aim of identify simple recommendation to improve communication strategies. Methods: Participants to the consensus received the results of the project and a selection of narratives two weeks before the meeting. The meeting was structured in plenary session and in three working groups discussing respectively about communication strategies with children, adolescents and parents. The task of each working group was to identify the most effective (DO) and least effective practices (DON' T) for 5 phases of the visit: welcome, comprehension of the context, emotions management, duration and end of the visit and endurance of the relationship. Results: Participants agreed that good relationships translate into positive outcomes and reached consensus on communication strategies to implement in the different phase of relationships. Conclusions: The future challenges identified by the participants are the dissemination of this Consensus document and the implementation of effective communication strategies to improve the management of pediatric asthma

Smoking in Systemic Sclerosis: a Longitudinal European Scleroderma Trials and Research Group Study

Data on the role of tobacco exposure in systemic sclerosis (SSc) severity and progression are scarce. We aimed to assess the effects of smoking on the evolution of pulmonary and skin manifestations in the EUSTAR database

Overall mortality in combined pulmonary fibrosis and emphysema related to systemic sclerosis

OBJECTIVES: This multicentre study aimed to investigate the overall mortality of combined pulmonary fibrosis and emphysema (CPFE) in systemic sclerosis (SSc) and to compare CPFE-SSc characteristics with those of other SSc subtypes (with interstitial lung disease-ILD, emphysema or neither). METHODS: Chest CTs, anamnestic data, immunological profile and pulmonary function tests of patients with SSc were retrospectively collected. Each chest CT underwent a semiquantitative assessment blindly performed by three radiologists. Patients were clustered in four groups: SSc-CPFE, SSc-ILD, SSc-emphysema and other-SSc (without ILD nor emphysema). The overall mortality of these groups was calculated by Kaplan-Meier method and compared with the stratified log-rank test; Kruskal-Wallis test, t-Student test and χ² test assessed the differences between groups. P<0.05 was considered statistically significant. RESULTS: We enrolled 470 patients (1959 patient-year); 15.5 % (73/470) died during the follow-up. Compared with the SSc-ILD and other-SSc, in SSc-CPFE there was a higher prevalence of males, lower anticentromere antibodies prevalence and a more reduced pulmonary function (p<0.05). The Kaplan-Meier survival analysis demonstrates a significantly worse survival in patients with SSc-CPFE (HR vs SSc-ILD, vs SSc-emphysema and vs other-SSc, respectively 1.6 (CI 0.5 to 5.2), 1.6 (CI 0.7 to 3.8) and 2.8 (CI 1.2 to 6.6). CONCLUSIONS: CPFE increases the mortality risk in SSc along with a highly impaired lung function. These findings strengthen the importance to take into account emphysema in patients with SSc with ILD