220 research outputs found
Seismic fragility and risk assessment of large bridge portfolios: efficient mechanical approaches based on multi-source data collection and integration
No full textIn earthquake-prone countries, most of the existing bridges were designed in the past without appropriate anti-seismic regulations and can induce important direct or indirect losses if subjected to severe seismic ground shaking. The main challenges in the extensive seismic risk assessment of existing bridges are related to the large number of structures to be inspected and the limited available resources. Therefore, time- and cost-saving approaches for providing seismic risk metrics on existing bridges are needed. This dissertation investigates efficient methodologies for bridge-specific seismic risk assessment within portfolio analysis by using multi-source data integration and simplified mechanical approaches.
A methodology for multi-source data collection is described. The applicability of remote-sensing data in populating inventory for structural analysis purposes is discussed. A procedure for using Remotely Piloted Aircraft Systems and photogrammetry to retrieve exhaustive structural information is presented.
The effectiveness of displacement-based assessment approaches to be used together with the capacity spectrum method (CSM) for seismic performance assessment is analysed, considering continuous-deck reinforced-concrete (RC) and steel truss multi-span bridges.
A fragility analysis methodology based on cloud analysis using the CSM results is also presented. The CSM is applied with real (i.e. recorded) ground-motion spectra (as opposed to code-based conventional spectra) to explicitly consider record-to-record variability.
A seismic risk assessment framework combining the proposed efficient data collection and simplified probabilistic seismic assessment methodologies is finally presented. It accounts for the influence of knowledge-based uncertainties associated with an initial incomplete data collection. The proposed approach is applied and tested on eight simply-supported RC bridges of the Basilicata national road network
DRUG DESIGN, SYNTHESIS AND STRUCTURE-ACTIVITY RELATIONSHIPS OF NOVEL MULTIMODAL INDOLE-FUSED TRICYCLIC DERIVATIVES TARGETING CANNABINOID-MODULATED G PROTEIN-COUPLED RECEPTORS AND CHOLINESTERASES
No full textDue to the multi-factorial nature of most neurological disorders, developing multi-target compounds is still considered among the effective approaches to developing neuroprotective drugs. Despite the scientific advances in the areas of neurochemistry, genetics, molecular and cell biology, there is still no effective treatment available that can delay the onset or slow the progression of neurodegenerative diseases, like Alzheimer’s disease (AD) and memory impairments. In the context of the challenging multitarget-directed-ligand (MTDL) design strategy of novel therapeutic agents for treating AD and related syndromes, progress has been made in the medicinal chemistry of drugs acting within and beyond the endocannabinoid system. Endogenous lipids, such as palmitoylethanolamide, that act simultaneously at GPCRs, ion channels, and PPARs can be taken as templates.
In this Ph.D. thesis study, starting from the structures of small-molecules inhibiting well-established AD-related targets, such as cholinesterases (AChE and BChE) and N-methyl-D-aspartate (NMDA) receptor, the synthesis has been carried out of novel rationally designed tricyclic indole-fused derivatives which interestingly proved to act as modulators (antagonists and/or inverse agonists) of the cannabinoid-related GPCRs GPR18 and GPR55, in some cases endowed with additional BChE-selective inhibition. The desired outcome is the combination of the anticholinesterase activity with the modulation of these poorly studied receptors, for a synergistic effect against neuroinflammation and neurodegeneration. Structure−activity relationships were analyzed, and selectivity versus cannabinoid (CB) and CB-like receptors was assessed. Chemical synthesis and analysis, radioligand binding and functional assays, enzymes’ inhibition kinetics and molecular modeling studies, in addition to allowing us to select candidates for in vivo pharmacological evaluation, provided us with useful medicinal chemistry information enabling the optimization of MTDLs against neurological disorders, potentially more effective than the currently available
Travelling-wave resonant four-wave mixing breaks the limits of cavity-enhanced all-optical wavelength conversion
No full textWave mixing inside optical resonators, while experiencing a large enhancement of the nonlinear interaction efficiency, suffers from strong bandwidth constraints, preventing its practical exploitation for processing broad-band signals. Here we show that such limits are overcome by the new concept of travelling-wave resonant four-wave mixing (FWM). This approach combines the efficiency enhancement provided by resonant propagation with a wide-band conversion process. Compared with conventional FWM in bare waveguides, it exhibits higher robustness against chromatic dispersion and propagation loss, while preserving transparency to modulation formats. Travelling-wave resonant FWM has been demonstrated in silicon-coupled ring resonators and was exploited to realize a 630-μm-long wavelength converter operating over a wavelength range wider than 60 nm and with 28-dB gain with respect to a bare waveguide of the same physical length. Full compatibility of the travelling-wave resonant FWM with optical signal processing applications has been demonstrated through signal retiming and reshaping at 10 Gb s(-1)
Travelling-wave resonant four-wave mixing on a silicon chip
No full textWe demonstrate that travelling-wave four-wave
mixing in coupled resonators overcomes the bandwidth
limitations of wavelength conversion in single resonators,
preserving the efficiency enhancement: 28-dB gain over silicon
waveguides of the same length is here achieved
Grating Assisted Coupling in Microring Resonators
No full textGrating Assisted Couplers (GACs) in Silicon-on-Insulator waveguides are studied experimentally as building blocks for optical integrated devices. By including them in a microring resonator configuration, we enhance the GAC wavelength selectivity and limit the resonance range of the microring. This device has the potential for small footprint, highly selective, wavelength filters and sensors
On the Use of Satellite-Based Interferometry for Structural Monitoring of Bridge Portfolios
No full textTransport network management authorities need to address targeted monitoring and structural assessment on appropriately selected critical bridges to improve the serviceability and safety of the network optimising the involved financial budgets and resources. The multi-temporal satellite-based differential interferometry, commonly referred to as MTInSAR, is a remote-sensing technique aimed at detecting displacements of coherent scatterers on the terrestrial surface with centimetre- to millimetre-level accuracy. This paper applies an MTInSAR-based methodology for the portfolio-scale evaluation of deformation phenomena on bridges, suitable for addressing targeted sensor-based monitoring or on-site inspection plans. The methodology is applied to a case-study highway network in Roma (Italy) by using Sentinel-1 (C-band) and COSMO-SkyMed (X-band) satellite datasets. The interferometry products are processed to identify bridge-specific deformation scenarios. The MTInSAR products and the deformation scenarios related to some specific test bridges subjected to subsidence phenomena are analysed to highlight the advantages and disadvantages of the investigated approach
Ochratoxin A and Aflatoxin B1 Detection in Laying Hens for Omega 3-Enriched Eggs Production
No full textMycotoxins are toxic secondary metabolites produced by fungal species that usually contaminate foods and feeds. Their lipophilic properties allow them to persist in the fat tissues of animals that ingest them, representing a risk for the consumers because of their toxicity and carcinogenicity. Apart from their toxicity to humans, there are species more susceptible to the mycotoxin actions, such as the avian ones. This report describes a case in a laying hen farm certified as antibiotic-free, where animals were fed with foodstuff with linseed added to obtain eggs enriched in omega-3 fat acids. In this case, the concurrent action of aflatoxin B1 and ochratoxin A caused a significant decrease in production and an increase in mortality. At pathologic examinations, the animals showed severe kidney degeneration along with liver lesions. The ovary and oviduct were hypoplastic, and evident signs of anemia were observed. Aflatoxin B1 and ochratoxin A were detected by HPLC in foodstuff with the addition of linseed and in organs. This case wants to drive attention to the importance of a careful check of the feedstuff to be used in poultry farms with a quality-oriented production, in order to avoid contaminations that can harm both animal welfare and public health
Trypanosoma (Megatrypanum) pestanai in Eurasian badgers (Meles meles) and Ixodidae ticks, Italy
No full textTrypanosomes are hemoflagellate protozoa transmitted by blood-feeding arthropods causing infections in a wide range of mammals, including humans. Adult badgers (Meles meles, n=2), displaying severe paralysis, ataxia and severe ectoparasite infestation, were rescued from a peri-urban area of Bari (southern Italy). Blood samples and ectoparasites were screened for Trypanosoma spp. by combined PCR/sequencing approach, targeting a fragment of 18S rRNA gene. Smears of hemolymph, guts and salivary glands of the alive ticks were microscopically observed. No hematological alterations, excepted thrombocytopenia, were found. Trypomastigotes and epimastigotes were observed in the blood smears of both badgers and Trypanosoma pestanai was molecularly identified. Out of 33 ticks (i.e., n=31 Ixodes canisuga, n=2 Ixodes ricinus) and 2 fleas (Ctenocephalides felis), 11 specimens (n=5 I. canisuga engorged nymphs, n=4 engorged females and n=2 I. ricinus engorged females) tested positive only for T. pestanai DNA. All smears from ticks were negative. The present study firstly revealed T. pestanai in Ixodidae and badgers from Italy, demonstrating the occurrence of the protozoan on the peninsula. Further studies are needed to clarify the occurrence of the only known vector of this parasite, Paraceras melis flea, as well as other putative arthropods involved in the transmission of T. pestanai
Environmental Causes of Idiopathic Pulmonary Fibrosis
No full textIdiopathic pulmonary fibrosis (IPF), the most common and severe of the idiopathic interstitial pneumonias, is a chronic and relentlessly progressive disease, which occurs mostly in middle-aged and elderly males. Although IPF is by definition “idiopathic”, multiple factors have been reported to increase disease risk, aging being the most prominent one. Several occupational and environmental exposures, including metal dust, wood dust and air pollution, as well as various lifestyle variables, including smoking and diet, have also been associated with an increased risk of IPF, probably through interaction with genetic factors. Many of the predisposing factors appear to act also as trigger for acute exacerbations of the disease, which herald a poor prognosis. The more recent literature on inhalation injuries has focused on the first responders in the World Trade Center attacks and military exposure. In this review, we present an overview of the environmental and occupational causes of IPF and its pathogenesis. While our list is not comprehensive, we have selected specific exposures to highlight based on their overall disease burden
Micro-Ring Resonators Based On Grating Assisted Couplers
No full textGrating Assisted Couplers (GACs) in Silicon-on-Insulator waveguides are studied numerically and experimentally. Their inclusion in a resonant micro-ring configuration enhances their selectivity and limits the resonance range of the microring. We show that a two-wave model based on coupled-mode theory should be replaced by a four-wave model in order to achieve correct device modeling, if the resonant behavior is of interest. This device has potential application for small footprint, highly selective, wavelength filters and sensors
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