1,721,093 research outputs found
GPS statico e statico rapido: effetto della configurazione satellitare
No full textVengono analizzati gli effetti della geometria satellitare sull'accuratezza di baselines GPS determinate in modalità statica o statico-rapida in post-processamento, in relazione ai valori assunti da indici di qualità della configurazione geometrica specifici per il posizionamento relativ
Glutathione as a natural TBT scavenger in immunosuppressive effect in ascidians
No full textTributyltin (TBT) is a widespread biocide belonging to organotin compounds, a group of important industrial chemicals which resulted severe environmental toxicants known to have detrimental effects on immune system. We have previously reported that incubation of haemocytes of the colonial ascidian Botryllus schlosseri to 10 μM TBT caused significant impairment in yeast phagocytosis, disassembly of cytoskeletal components and induction of apoptosis as a consequence of direct interaction on calmodulin affecting Ca2+ homeostasis. However, in the presence of exogenous calmodulin, although Ca2+-ATPase activity and amoeboid morphology of phagocytes were restored, phagocytosis index, i.e., the percentage of haemocytes containing yeast cells, was still inhibited, indicating that, as suggested for rat thymocytes, the potent immunotoxic effect of TBT occurs with both Ca2+-dependent and Ca2+-independent mechanism.
With the aim to study the capability of TBT to oxidise intracellular thiols, we first assessed the fraction of phagocytes stained by mercury orange - a specific dye for total thiols - and chlorobimane - a fluorescent dye for reduced glutathione - after exposition to 0.1, 1, 10 μM TBT for 1 h. In both cases, we observed a significant decrease in thiol content already after exposition to 0.1 μM TBT. Evaluation of amoebocytic index, i.e., the percentage of haemocytes with amoeboid shape, after co-incubation with 1 μM TBT and increasing concentrations (10, 20, 50 mM) of exogenous sulphydryl compounds revealed the ability of the latter compounds to restore cell morphology beginning from 20 mM for L-cysteine, reduced glutathione, and the glutathione fragment L-cysteinyl-glutamic acid (-Glu-Cys), whereas L-cystine, N-acetylcysteine, oxidised glutathione, and the glutathione fragment L-cysteinyl-glycine (Cys-Gly, probably resulting in 2,5 diketopiperazine derivative) had no restoring effect. Parallel experiments to evaluate the percentage of phagocytes containing tin, revealed with cacotheline dye, showed a perfectly symmetrical trend after co-incubation of TBT and sulphydryl compounds, indicating a scavenger ability of the natural thiol-compounds bearing free amino and carboxyl groups. As regards glutathione content, isodynamic mixtures of TBT and carmustine (BCNU, a specific inhibitor of glutathione-reductase) showed indifferent behaviour, while those of TBT and N-ethylmaleimide (NEM, an alkylating agent which specifically binds to thiol groups) showed an antagonistic interaction. Moreover, positivity to both glutathione-transferase (GST) and glutathione-peroxidase (GPX) antibody, revealed through immunocytochemical localisation, disappeared after incubation of 1 μM TBT, suggesting conformational changes probably due to direct interaction of the xenobiotic with these antioxidant enzymes involved in detoxification metabolic processes.
In conclusion, our results suggest that i) oxidation of thiol groups, a process known to affect cytoskeletal proteins, may be involved in TBT immunotoxicity together with calmodulin interaction, ii) TBT causes depletion in glutathione content through direct interaction with both reduced glutathione and glutathione-dependent enzymes as GST and GPX, iii) although TBT does not interact directly with glutathione-reductase, the activity of this enzyme is inadequate to restore the reduced state of glutathione: the presence of high amounts of oxidised glutathione causes stimulation of Ca2+-releasing property of the inositol-1,4,5,-trisphosphate receptor and both the resulting calcium mobilisation and inhibition of calmodulin-dependent Ca2+-ATPase, increase the intracellular calcium content, and trigger a cascade of secondary events which lead to cell death
Comparison of a local geoid model with a precise levelling network
No full textThis work presents the results of a GPS-LEV measurement campaign carried out on a number of leveling benchmarks part of the Italian national high-precision leveling network, for an extension of some tenths of kilometers around the GPS permanent station of Perugia (UNPG - part of the IGS, EUREF and ASI networks), in central Italy.
A comparison has been made between the geoid undulations locally derived from GPS-LEV and the values given by some geoid models, both global (EGM 96) and national (ITALGEO 95, ITALGEO 99).
The results show that the estimated geoidal heights derived from the correction of GPS-measured ellipsoidal heights with any geoid model need to be “fitted” in some way to the orthometric heights given by the leveling network covering the survey area, thus to the vertical datum as "realised" by the leveling network.
The reason could be the “smoothness” of the geoid model and/or a slight difference in the datum definition between the GPS survey and the geoid model itself.
Some different fitting techniques have been experimented, obtaining acceptable results for technical purposes
Utilizzo delle immagini satellitari ad alta risoluzione come supporto al monitoraggio di una zona costiera
No full textGeomatic techniques for utilities consumption analysis in urban areas during emergency periods
No full textThis paper has the main purpose of proposing a methodology to understand the occupation of parking spots by using the synergy of different geomatic techniques. Aerial, satellites, and UAV data are studied through the OBIA to analyse, by change detection, the main differences pre-, during and post-lockdown due to Covid-19. The first results are really promising and pave the ground for a fu-ture automation of the proposed procedure. The results can be also integrated in BIM and GIS to help the management of utilities consumption in emergency periods, and they create a dataset to enhance and increase consumption efficiency in residential areas
LiDAR-Based Road Cracking Detection: Machine Learning Comparison, Intensity Normalization, and Open-Source WebGIS for Infrastructure Maintenance
Full text linkThis study introduces an innovative and scalable approach for automated road surface assessment by integrating Mobile Mapping System (MMS)-based LiDAR data analysis with an open-source WebGIS platform. In a U.S.-based case study, over 20 datasets were collected along Interstate I-65 in West Lafayette, Indiana, using the Purdue Wheel-based Mobile Mapping System-Ultra High Accuracy (PWMMS-UHA), following Indiana Department of Transportation (INDOT) guidelines. Preprocessing included noise removal, resolution reduction to 2 cm, and ground/non-ground separation using the Cloth Simulation Filter (CSF), resulting in Bare Earth (BE), Digital Terrain Model (DTM), and Above Ground (AG) point clouds. The optimized BE layer, enriched with intensity and color information, enabled crack detection through Density-Based Spatial Clustering of Applications with Noise (DBSCAN) and Random Forest (RF) classification, with and without intensity normalization. DBSCAN parameter tuning was guided by silhouette scores, while model performance was evaluated using precision, recall, F1-score, and the Jaccard Index, benchmarked against reference data. Results demonstrate that RF consistently outperformed DBSCAN, particularly under intensity normalization, achieving Jaccard Index values of 94% for longitudinal and 88% for transverse cracks. A key contribution of this work is the integration of geospatial analytics into an interactive, open-source WebGIS environment-developed using Blender, QGIS, and Lizmap-to support predictive maintenance planning. Moreover, intervention thresholds were defined based on crack surface area, aligned with the Pavement Condition Index (PCI) and FHWA standards, offering a data-driven framework for infrastructure monitoring. This study emphasizes the practical advantages of comparing clustering and machine learning techniques on 3D LiDAR point clouds, both with and without intensity normalization, and proposes a replicable, computationally efficient alternative to deep learning methods, which often require extensive training datasets and high computational resources
Terremoto dell’Aquila del 6 aprile 2009: prime valutazioni degli spostamenti superficiali
No full textUtilizzando dati delle reti di stazioni permanenti dell'Abruzzo, dell'Umbria ed EUREF viene eseguita una determinazione delle deformazioni crostali indotte dal sisma del 2009 nella zona dell'Aquil
Remote Sensing in Coastline Detection
No full text“Is beach erosion a natural cycle or is it getting worse with rising sea levels [...
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