Respiratory symptoms in children living near busy roads and their relationship to vehicular traffic: results of an Italian multicenter study (SIDRIA 2)

BACKGROUND: Epidemiological studies have provided evidence that exposure to vehicular traffic increases the prevalence of respiratory symptoms and may exacerbate pre-existing asthma in children. Self-reported exposure to road traffic has been questioned as a reliable measurement of exposure to air pollutants. The aim of this study was to investigate whether there were specific effects of cars and trucks traffic on current asthma symptoms (i.e. wheezing) and cough or phlegm, and to examine the validity of self-reported traffic exposure. METHODS: The survey was conducted in 2002 in 12 centers in Northern, Center and Southern Italy, different in size, climate, latitude and level of urbanization. Standardized questionnaires filled in by parents were used to collect information on health outcomes and exposure to traffic among 33,632 6-7 and 13-14 years old children and adolescents. Three questions on traffic exposure were asked: the traffic in the zone of residence, the frequency of truck and of car traffic in the street of residence. The presence of a possible response bias for the self-reported traffic was evaluated using external validation (comparison with measurements of traffic flow in the city of Turin) and internal validations (matching by census block, in the cities of Turin, Milan and Rome). RESULTS: Overall traffic density was weakly associated with asthma symptoms but there was a stronger association with cough or phlegm (high traffic density OR = 1.24; 95% CI: 1.04, 1.49). Car and truck traffic were independently associated with cough or phlegm. The results of the external validation did not support the existence of a reporting bias for the observed associations, for all the self-reported traffic indicators examined. The internal validations showed that the observed association between traffic density in the zone of residence and respiratory symptoms did not appear to be explained by an over reporting of traffic by parents of symptomatic subjects. CONCLUSION: Children living in zones with intense traffic are at higher risk for respiratory effects. Since population characteristics are specific, the results of validation of studies on self-reported traffic exposure can not be generalized

Pediatric astrocytomas with monomorphous pilomyxoid features and a less favorable outcome

Among tumors classified as pilocytic astrocytoma (PA) in the Johns Hopkins Hospital Department of Pathology files, we identified 18 cases with a distinctive monomorphous pilomyxoid histological pattern and a higher recurrence rate than that of PA with classical histological features (classical PA). The majority of the tumors occurred in infants and young children and involved the hypothalamic/chiasmatic region. The tumors were histologically similar to PA, but they were more monomorphous and more myxoid. Rosenthal fibers were not seen and only 1 of 18 tumors had eosinophilic granular bodies. At the end of the follow-up period, 6 patients were dead and 12 were alive with evidence of disease. Progression free survival (PFS) at 1 year was 38.7%. In comparison, we identified a control group of 13 classical PAs in the same age range and location as the study group. In this group, PFS at 1 year was 69.2%, which was significantly better than that for pilomyxoid tumors (p = 0.04). There was no CSF dissemination or death due to tumor progression among patients with classical PA. Eight of these patients are alive with recurrent disease, and 4 have no evidence of disease. While the monomorphous pilomyxoid tumors have some resemblance to classical PA, our results suggest that the former is a more aggressive variant or a separate entity that needs to be recognized for prognostic purposes

Energy consistency in homogenisation-based upscaling scheme for localisation in masonry shells

This paper presents an enhanced multi-scale framework for the failure of quasi-brittle thin shells as an improvement of the one proposed in Mercatoris and Massart (Int J Numer Methods Eng 85:1177-1206, 2011). The computational homogenisation-based multi-scale methodology is an attractive solution for heterogeneous materials when their characterisation becomes difficult because of complex evolving behaviour such as damage-induced anisotropy and localisation of degradation. An enhanced upscaling scheme for damage localisation in shell structures is proposed using a periodic computational homogenisation procedure and an energy equivalence between mesostructural material instabilities and aggregate macroscopic cracks. The structural cracking is treated by using embedded strong discontinuities incorporated in the shell formulation, the behaviour of which is deduced by an energetically consistent upscaling scheme. The effects of this energy equivalence are discussed based on results of multi-scale simulations of out-of-plane loaded masonry walls including flexural stair-case failure and compared to the results of direct numerical simulations. A good agreement is observed in terms of the load-bearing capacity and of associated energy dissipation. Based on the homogenisation procedure, the orientation of the structural-scale cracking is detected by means of an acoustic tensor-based failure detection adapted to shell kinematics. A multi-scale bifurcation analysis on a simple loading case is performed in order to discuss the selection of the cracking orientation based on energetic considerations. © 2012 Springer Science+Business Media B.V