630 research outputs found
Short-Training Damage Detection Method for Axially Loaded Beams Subject to Seasonal Thermal Variations
Vibration-based damage features are widely adopted in the field of structural health monitoring (SHM), and particularly in the monitoring of axially loaded beams, due to their high sensitivity to damage-related changes in structural properties. However, changes in environmental and operating conditions often cause damage feature variations which can mask any possible change due to damage, thus strongly affecting the effectiveness of the monitoring strategy. Most of the approaches proposed to tackle this problem rely on the availability of a wide training dataset, accounting for the most part of the damage feature variability due to environmental and operating conditions. These approaches are reliable when a complete training set is available, and this represents a significant limitation in applications where only a short training set can be used. This often occurs when SHM systems aim at monitoring the health state of an already existing and possibly already damaged structure (e.g., tie-rods in historical buildings), or for systems which can undergo rapid deterioration. To overcome this limit, this work proposes a new damage index not affected by environmental conditions and able to properly detect system damages, even in case of short training set. The proposed index is based on the principal component analysis (PCA) of vibration-based damage features. PCA is shown to allow for a simple filtering procedure of the operating and environmental effects on the damage feature, thus avoiding any dependence on the extent of the training set. The proposed index effectiveness is shown through both simulated and experimental case studies related to an axially loaded beam-like structure, and it is compared with a Mahalanobis square distance-based index, as a reference. The obtained results highlight the capability of the proposed index in filtering out the temperature effects on a multivariate damage feature composed of eigenfrequencies, in case of both short and long training set. Moreover, the proposed PCA-based strategy is shown to outperform the benchmark one, both in terms of temperature dependency and damage sensitivity
The evolutionary history of a mammal species with a highly fragmented range: the phylogeography of the European snow vole.
The European snow vole Chionomys nivalis has a patchy distribution restricted to
rocky habitats across southern Europe and the Near and Middle East. We carried
out a phylogeographic study to provide a biogeographic scenario, based on
molecular data, outlining the major processes that determined the current
distribution of the species. The samples include 26 snow voles from 14 different
populations across the entire species range from Spain to Anatolia and Israel.
Nearly complete sequences (1037 bp) of the mitochondrial gene for cytochrome b
were sequenced. Relationships among haplotypes were inferred with neighbourjoining,
maximum likelihood, maximum parsimony analyses and minimum spanning
network. An analysis of mismatch distribution was used to cast light on past
demographic expansion. We found 22 different haplotypes that fall into six distinct
lineages, all but one is supported by high bootstrap values with all methods. Four
lineages are allopatric (Tatra Mts., Iberia, Balkans and Middle East) while
divergent haplotypes from two lineages show sympatry in the Alps and the
Apennines. The basal relationships of these lineages could not be established by
any tree. The mean pairwise genetic distance between lineages ranges from 2.4 to
4.2%. The shape of the mismatch distribution indicated a past expansion event
dating back to between 158 000 and 84 000 years ago. These data can be interpreted
with the existence of southern glacial refugia (Iberia, Balkans, Middle East and
Italy) and one additional northern glacial refugium. The lack of phylogenetic
resolution among lineages and the shape of mismatch distribution are indicative of
a simultaneous and rapid splitting due to a relatively fast initial expansion of
populations. Moreover, the analysis supports the hypothesis of the European
origin of C. nivalis and its subsequent eastward dispersion during the Middle
Pleistocene
Antimicrobial effects of chemically functionalized and/or photo-heated nanoparticles
Antibiotic resistance refers to when microorganisms survive and grow in the presence of specific antibiotics, a phenomenon mainly related to the indiscriminate widespread use and abuse of antibiotics. In this framework, thanks to the design and fabrication of original functional nanomaterials, nanotechnology offers a powerful weapon against several diseases such as cancer and pathogenic illness. Smart nanomaterials, such as metallic nanoparticles and semiconductor nanocrystals, enable the realization of novel drug-free medical therapies for fighting against antibiotic-resistant bacteria. In the light of the latest developments, we highlight the outstanding capabilities of several nanotechnology-inspired approaches to kill antibiotic-resistant bacteria. Chemically functionalized silver and titanium dioxide nanoparticles have been employed for their intrinsic toxicity, which enables them to exhibit an antimicrobial activity while, in a different approach, photo-thermal properties of metallic nanoparticles have been theoretically studied and experimentally tested against several temperature sensitive (mesophilic) bacteria. We also show that it is possible to combine a highly localized targeting with a plasmonic-based heating therapy by properly functionalizing nanoparticle surfaces with covalently linked antibodies. As a perspective, the utilization of properly engineered and chemically functionalized nanomaterials opens a new roads for realizing antibiotic free treatments against pathogens and related diseases
Third-hand smoking: indoor measurements of concentration and sizes of cigarette smoke particles after resuspension
International audienc
Mode of Delivery and Asthma at School Age in 9 European Birth Cohorts
Evidence on the association between mode of delivery and asthma at school age is inconclusive. We assessed the associations between specific modes of delivery and asthma in children from 9 European birth cohorts that enrolled participants between 1996 and 2006. Cohort-specific crude and adjusted risk ratios for asthma at ages 5–9 years were calculated using Poisson regression models and pooled. A sensitivity analysis was carried out in children born at term to reduce confounding due to perinatal factors. The study included 67,613 participants. Cohortspecific rates of cesarean delivery varied from 9.4% to 37.5%. Cesarean delivery, as opposed to vaginal delivery, was associated with an increased risk of asthma (adjusted risk ratio (aRR) = 1.22, 95% confidence interval (CI): 1.02, 1.46). Compared with spontaneous vaginal delivery, the adjusted risk ratio was 1.33 (95% CI: 1.02, 1.75) for elective cesarean delivery, 1.07 (95% CI: 0.94, 1.22) for emergency cesarean delivery, and 0.97 (95% CI: 0.84, 1.12) for operative vaginal delivery. In children born at term, the associations were strengthened only for elective cesarean delivery (aRR = 1.49, 95% CI: 1.13, 1.97). The large sample size allowed analysis of the associations between specific modes of delivery and asthma at school age. The increased risk of asthma associated with elective cesarean delivery, especially among children born at term, is relevant in counteracting the increasing use of this procedure, which is often performed without a clear medical indication.This work was supported by the European Community’s Seventh Framework Programme (FP7/2009–2013) under a grant agreement (grant 241604) and by the University of Turin and the San Paolo Foundation (Turin, Italy). Data collection was funded and the study teams of all participating birth cohorts were supported by local and/or national research organizations
Maternal caffeine consumption during pregnancy and offspring cord blood DNA methylation:an epigenome-wide association study meta-analysis
Background: Prenatal caffeine exposure may influence offspring health via DNA methylation, but no large studies have tested this. Materials & methods: Epigenome-wide association studies and differentially methylated regions in cord blood (450k or EPIC Illumina arrays) were meta-analyzed across six European cohorts (n = 3725). Differential methylation related to self-reported caffeine intake (mg/day) from coffee, tea and cola was compared with assess whether caffeine is driving effects. Results: One CpG site (cg19370043, PRRX1) was associated with caffeine and another (cg14591243, STAG1) with cola intake. A total of 12-22 differentially methylated regions were detected with limited overlap across caffeinated beverages. Conclusion: We found little evidence to support an intrauterine effect of caffeine on offspring DNA methylation. Statistical power limitations may have impacted our findings. </p
Sterile inflammation via TRPM8 RNA-dependent TLR3-NF-kB/IRF3 activation promotes antitumor immunity in prostate cancer
Inflammation is a common condition of prostate tissue, whose impact on carcinogenesis is highly debated. Microbial colonization is a well-documented cause of a small percentage of prostatitis cases, but it remains unclear what underlies the majority of sterile inflammation reported. Here, androgen- independent fluctuations of PSA expression in prostate cells have lead us to identify a prominent function of the Transient Receptor Potential Cation Channel Subfamily M Member 8 (TRPM8) gene in sterile inflammation. Prostate cells secret TRPM8 RNA into extracellular vesicles (EVs), which primes TLR3/NF-kB-mediated inflammatory signaling after EV endocytosis by epithelial cancer cells. Furthermore, prostate cancer xenografts expressing a translation-defective form of TRPM8 RNA contain less collagen type I in the extracellular matrix, significantly more infiltrating NK cells, and larger necrotic areas as compared to control xenografts. These findings imply sustained, androgen-independent expression of TRPM8 constitutes as a promoter of anticancer innate immunity, which may constitute a clinically relevant condition affecting prostate cancer prognosis
Physical Activity After Surgery for Severe Obesity: The Role of Exercise Cognitions
# The Author(s) 2010. This article is published with open access at Springerlink.com Background Physical activity after bariatric surgery is associated with sustained weight loss and improved quality of life. Some bariatric patients engage insufficiently in physical activity. This may be due to exercise cognitions, i.e., specific beliefs about benefits of and barriers to physical exercise. The aim of this study was to examine whether and to what extent both physical activity and exercise cognitions changed at 1 and 2 years post-surgery and whether exercise cognitions predict physical activity. Methods Forty-two bariatric patients (38 women, 4 men; mean age 38±8 years, mean body mass index prior to surgery 47±6 kg/m 2) filled out self-report instruments to examine physical activity and exercise cognitions pre- and post-surgery
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