411 research outputs found
Towards the development of a MEMS-based health monitoring system for lightweight structures
We recently proposed a surface-mounted structural health monitoring (SHM) scheme based on commercial, low-cost inertial MEMS sensors. While such commercial-off-the-shelf sensors are not very accurate, their low cost and negligible weight allow them to be deployed in dense arrays, possibly overcoming inaccuracy through redundancy. Taking the sensor characteristics into account, the development of a MEMS-based SHM method for lightweight structures like thin plates, is tackled from two different viewpoints: sensor accuracy verification, and optimal sensor placement. To assess the accuracy, a preliminary investigation was run on standard composite specimens for delamination testing, adopting a single MEMS three-axis accelerometer. A theoretical interpretation of the results, based on beam bending theory, showed the ability of the system to provide a one-to-one relationship between the delamination length and the sensor output. Concerning the placement of the sensors, an approach for their optimal deployment was developed, using a topology optimization-like formulation. Such formulation looks for the optimal layout of the network by maximizing the overall sensitivity of the output to a damage possibly located anywhere. In this work, accounting for the characteristic sizes of a structural element and of the MEMS package, which might differ by orders of magnitude, we introduce a multi-scale (actually, two-scale) approach to sensor deployment. It is shown that, no matter what the location and size of the damaged area are, a trivial array of evenly spaced sensors does not represent the optimal solution for SHM
Role of air pollutants mediated oxidative stress in respiratory diseases
Airborne particulate (PM) components from fossil fuel combustion can induce oxidative stress initiated by reactive oxygen species (ROS) that are strongly correlated with airway inflammation and asthma. A valid biomarker of airway inflammation is fractionated exhaled nitric oxide (FENO). The oxidative potential of PM2.5 can be evaluated with the dithiothreitol (DTT) dosage, which represents both ROS chemically produced and intracellular ROS of macrophages. This correlates with quality indicators of the internal environment and ventilation strategies such as dilution and removal of airborne contaminants
Vitamin D and rheumatic diseases.
Vitamin D has some well-known effects on calcium, phosphate and bone metabolism, but it has recently shown to have many other effects, which may potentially be relevant to patients with extra-skeletal rheumatic diseases. Such effects may be justified by: 1) the presence of the vitamin D receptors also on extra-osseous cells, such as cartilage cells, sinoviocytes, muscle cells; 2) the proven role of vitamin D in the control of the transcription of genes involved in rheumatic diseases; 3) the evidence that vitamin D has multiple endocrine effects not only on calcium homeostasis; 4) the activation of vitamin D not only in the kidneys, but also in monocyte-macrophage and lymphocytic cell lines and in some epithelial cells with additional intracrine and paracrine effects. Vitamin D deficiency has been reported in numerous metabolic, degenerative, inflammatory and autoimmune rheumatic diseases. In some cases this association was also related to the risk of developing a rheumatic disease or the degree of disease activity. However there is no conclusive evidence of the efficacy of a preventive or therapeutic strategy based on vitamin D supplementation in extra-skeletal rheumatic diseases. This review aims to provide an overview of the latest evidence concerning the relationship between vitamin D and the most relevant rheumatic diseases
Oxygen abundance in local disk and bulge: chemical evolution with a strictly universal IMF
The empirical differential oxygen abundance distribution (EDOD) is deduced
from subsamples related to two different samples involving solar neighbourhood
(SN) thick disk, thin disk, halo, and bulge stars. The EDOD of the SN thick +
thin disk is determined by weighting the mass, for assumed SN thick to thin
disk mass ratio within the range, 0.1-0.9. Inhomogeneous models of chemical
evolution for the SN thick disk, the SN thin disk, the SN thick + thin disk,
the SN halo, and the bulge, are computed assuming the instantaneous recycling
approximation. The EDOD data are fitted, to an acceptable extent, by their TDOD
counterparts provided (i) still undetected, low-oxygen abundance thin disk
stars exist, and (ii) a single oxygen overabundant star is removed from a thin
disk subsample. In any case, the (assumed power-law) stellar initial mass
function (IMF) is universal but gas can be inhibited from, or enhanced in,
forming stars at different rates with respect to a selected reference case.
Models involving a strictly universal IMF (i.e. gas neither inhibited from, nor
enhanced in, forming stars with respect to a selected reference case) can also
reproduce the data. The existence of a strictly universal IMF makes similar
chemical enrichment within active (i.e. undergoing star formation) regions
placed in different environments, but increasing probability of a region being
active passing from SN halo to SN thick + thin disk, SN thin disk, SN thick
disk, and bulge. On the basis of the results, it is realized that the chemical
evolution of the SN thick + thin disk as a whole cannot be excluded.Comment: 26 pages, 10 tables, and 5 figures; tables out of page are splitted
in two parts in Appendix B; sects.4 and 5 rewritten for better understanding
of the results; further references added. Accepted for publication in
Astrophysics & Space Scienc
Toward Understanding the origin of the Fundamental Plane for Early-Type Galaxies
We present a panoramic review of several observational and theoretical
aspects of the modern astrophysical research about the origin of the
Fundamental Plane (FP) relation for Early-Type Galaxies (ETGs). The discussion
is focused on the problem of the tilt and the tightness of the FP, and on the
attempts to derive the luminosity evolution of ETGs with redshift. Finally, a
number of observed features in the FP are interpreted from the standpoint of a
new theoretical approach based on the two-component tensor virial theorem.Comment: 30 pages, 3 figure
Is it possible to make a diagnosis of raw, heated and baked egg allergy in children using cut-offs? A systematic review
The diagnosis of IgE-mediated egg allergy lies both on a compatible clinical history and on the results of skin prick tests (SPTs) and IgEs levels. Both tests have good sensitivity but low specificity. For this reason, oral food challenge (OFC) is the ultimate gold standard for the diagnosis. The aim of the present paper is to systematically review the literature in order to identify, analyze and synthesize the predictive value of SPT and specific IgEs both to egg white and main egg allergens and to review the cut-offs suggested in the literature
Allergy and covid-19
The first cases of as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection have been reported in Wuhan, China in December 2019. The World Health Organization declared the global pandemic in March 2020. Coronavirus disease 2019 (COVID-19) showed high rates of mortality in the adult popula-tion, whereas a mild course was observed in childhood. Allergic diseases, characterized by a type-2 polariza-tion of the immune system, were considered one of the major risk factor of severe COVID-19. Large amounts of clinical data and expert opinions have been collected since the pandemic outbreak. This review summarizes the latest insights on COVID-19 and allergy. (www.actabiomedica.it)
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