55 research outputs found

    Studio delle problematiche delle infiltrazioni e perdite della diga di Medau Zirimilis (Sardegna SW)

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    The costruction earthfill dam Medau Zirimilis, in the territory of Siliqua (SW Sardinia), began in 1989 and ended in 1991. Over the years, a time series of experimental basins, showed several problems of leakage and filtration in dam body. In the present work, through the application of classical methods of hydrogeology and applied, we have studied the problems of infiltration and loss of earth dam of Medau Zirimilis. The research has tried to examine the causes of the existing problems and identify possible solutions. The work of investigation has been developed from the acquisition of a basic knowledge of the geological characteristics of the tax of the dam and its surroundings. The understanding of its technical and constructional features and behavior had the objective to increase the level of reservoir . For this purpose, during the research have been acquired experimental data on levels in various types of water wells and drainage of the dam. Through the elaboration and interpretation with GIS methodologies and software, the attempt of this research was to reconstruct the model of the aquifer and to identify possible preferential of flow paths. Always with the purpose of identifying pathways of water, we have been carried out a study on the mantle of coating internal hangings of the bank barrage made in bituminous conglomerate, applying innovative methodologies, techniques by such as non-destructive surveys to infrared thermography

    Indagini termografiche, trasformazioni architettoniche e degrado dei materiali nelle chiese del centro storico di Siliqua (Sardegna S-W)

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    La termografia a raggi infrarossi, come noto, consente l’analisi strutturale di manufatti edilizi sulla base dell’individuazione di zone a differente temperatura e di possibili processi di scambio termico in stretta relazione con la risposta dei materiali utilizzati alle sollecitazioni termiche a cui sono interessati. Le immagini termiche, soprattutto se acquisite mediante strumentazione caratterizzata da elevata risoluzione e sensibilità, consentono di mettere in evidenza, oltre alla presenza di anomalie legate a processi di alterazione e degradazione dei materiali utilizzati, eventuali trasformazioni architettoniche avvenute nella storia del manufatto e, in particolare, caratteri costruttivi originari nascosti da interventi posteriori. Sulla base di questi presupposti, vengono esposti i risultati di una indagine applicata per lo studio di alcuni tra gli edifici storico-religiosi presenti nel paese di Siliqua (Sardegna sud-occidentale): la Chiesa di San Giorgio, la Chiesa di Sant’Anna e la Chiesa di Santa Margherita. La ricerca, in particolare, ha consentito di mettere in evidenza la struttura e la tessitura muraria dei prospetti principali, oggi coperta dall’intonaco e, sulla base di documenti storici e delle immagini fotografiche del passato, tarare la risposta termica acquisita in base alle specifiche caratteristiche dei materiali utilizzati. Lo studio è stato condotto mediante l’utilizzo della Termocamera IR Thermo Tracer TH9260 (NEC Avio Infrared Technologies Co., Ltd).Infrared thermography, as known, allows the analysis of structural building elements on the basis of the identification of areas at different temperatures and possible heat transfer processes in close relationship with the response of the materials used to thermal stresses to which they are interested. The thermal images, especially if acquired through instrumentation characterized by high resolution and sensitivity, allow to put in evidence, in addition to the presence of anomalies associated with processes of alteration and degradation of the materials used, any architectural transformations occurred in the history of the article and, in particular, original characters constructive hidden by later interventions. Based on these assumptions, the thermographic method has been applied to the study of some of the historical and religious buildings in the country of Siliqua (south-western Sardinia): the Church of San Giorgio, the Church of Sant’Anna and the Church of Santa Margherita. The research, in particular, has made it possible to highlight the structure and texture of the main elevations of walls, now covered by plaster, and, on the basis of historical documents and photographs of the past, adjust the thermal response acquired with the specific materials used. The study has been carried through non-destructive telemetry investigations through the use of Thermal Imaging Camera IR Thermo Tracer TH9260 (NEC Avio Infrared Technologies Co., Ltd)

    Assessing the effect of rotational grazing adoption in Iberian silvopastoral systems with Normalized Difference Vegetation Index time series

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    Adaptive Multi-Paddock (AMP) is a grazing system which combines intensive, rapid grazing livestock rotation with relatively short grazing periods and long recovery time after grazing. The study assesses, under Mediterranean silvopastoral systems, changes in pasture phenology and spatial variability after adopting the AMP under contrasting land cover (Wooded Grassland vs Grassland ) with a remote sensing approach based on the time-series analysis of Normalized Difference Vegetation Index (NDVI) from remote sensing through Landsat satellite. The study revealed an overall positive effect of rotational grazing on pasture phenology and NDVI spatial variability. The AMP adoption resulted in higher estimated values of NDVI at the beginning (under grassland land cover), the end, and the peak of the growing season, while no differences were observed in parameters estimating the length of the growing season. The spatial variability of NDVI was always lower under AMP than in continuously grazed areas, except in the early stages of the growing season under grassland land cover. The results suggested that in a relatively short period (4-5 years), the AMP grazing system can represent a strategy to improve forage availability and exploitation by grazing animals under low stocking rates in extensively managed Mediterranean silvopastoral systems

    Haplotype affinities resolve a major component of goat (<i>Capra hircus</i>) MtDNA D-loop diversity and reveal specific features of the Sardinian stock

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    Goat mtDNA haplogroup A is a poorly resolved lineage absorbing most of the overall diversity and is found in locations as distant as Eastern Asia and Southern Africa. Its phylogenetic dissection would cast light on an important portion of the spread of goat breeding. The aims of this work were 1) to provide an operational definition of meaningful mtDNA units within haplogroup A, 2) to investigate the mechanisms underlying the maintenance of diversity by considering the modes of selection operated by breeders and 3) to identify the peculiarities of Sardinian mtDNA types. We sequenced the mtDNA D-loop in a large sample of animals (1,591) which represents a non-trivial quota of the entire goat population of Sardinia. We found that Sardinia mirrors a large quota of mtDNA diversity of Western Eurasia in the number of variable sites, their mutational pattern and allele frequency. By using Bayesian analysis, a distance-based tree and a network analysis, we recognized demographically coherent groups of sequences identified by particular subsets of the variable positions. The results showed that this assignment system could be reproduced in other studies, capturing the greatest part of haplotype diversity. We identified haplotype groups overrepresented in Sardinian goats as a result of founder effects. We found that breeders maintain diversity of matrilines most likely through equalization of the reproductive potential. Moreover, the relevant amount of inter-farm mtDNA diversity found does not increase proportionally with distance. Our results illustrate the effects of breeding practices on the composition of maternal gene pool and identify mtDNA types that may be considered in projects aimed at retrieving the maternal component of the oldest breeds of Sardinia.</br

    Analoghi di sintesi del feromone sessuale come strumento per il controllo della popolazione di <i>Lymantria dispar</i>

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    La strategia riproduttiva delle farfalle notturne è basata sull’utilizzo di un feromone speciespecifico, prodotto dagli esemplari femminili per il richiamo a lunga distanza degli individui maschi conspecifici. In particolare le femmine di Lymantria dispar, uno dei più importanti insetti fitofagi defogliatori delle sugherete sarde, elaborano un feromone costituito da un unico componente, chiamato (+)disparlure (2-methyl-7,8-epoxy-octadecane) e lo accumulano nella ghiandola del feromone fino al rilascio. Nel presente lavoro abbiamo sintetizzato diversi analoghi del feromone naturale, allo scopo di ottenere molecole con un maggiore potere attrattivo sugli esemplari maschili, o più stabili nel tempo, ossia dotate di tempi di decadimento più lunghi

    Geomorphology and sedimentology of Porto Pino, SW Sardinia, Western Mediterranean

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    This paper presents a detailed (1:4000) geomorphological, sedimentological and ecological map of a Mediterranean microtidal wave-dominated beach system and adjacent inner shelf. This map is an innovative cartographic product that integrates a range of processes of present and past timeframes. It is part of a larger cartography on the coastal geomorphology of Sardinia (Italy) aiming to facilitate coastal management practices and future scientific research. The study area is located in SW Sardinia (Italy), and focuses on Porto Pino beach, an important tourist destination of semi-pristine nature, facing environmental pressures common to many coastal Mediterranean settings. In this context, the main human impact on coastal dune habitats is described and a full environmental characterization of the beach system is presented

    Population Based Study of 12 Autoimmune Diseases in Sardinia, Italy: Prevalence and Comorbidity

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    BACKGROUND: The limited availability of prevalence data based on a representative sample of the general population, and the limited number of diseases considered in studies about co-morbidity are the critical factors in study of autoimmune diseases. This paper describes the prevalence of 12 autoimmune diseases in a representative sample of the general population in the South of Sardinia, Italy, and tests the hypothesis of an overall association among these diseases. METHODS: Data were obtained from 21 GPs. The sample included 25,885 people. Prevalence data were expressed with 95% Poisson C.I. The hypothesis of an overall association between autoimmune diseases was tested by evaluating the co-occurrence within individuals. RESULTS: Prevalence per 100,000 are: 552 rheumatoid arthritis, 124 ulcerative colitis, 15 Crohn's disease, 464 type 1 diabetes, 81 systemic lupus erythematosus, 124 celiac disease, 35 myasthenia gravis, 939 psoriasis/psoriatic arthritis, 35 systemic sclerosis, 224 multiple sclerosis, 31 Sjogren's syndrome, and 2,619 autoimmune thyroiditis. An overall association between autoimmune disorders was highlighted. CONCLUSIONS: The comparisons with prevalence reported in current literature do not show outlier values, except possibly for a few diseases like celiac disease and myasthenia gravis. People already affected by a first autoimmune disease have a higher probability of being affected by a second autoimmune disorder. In the present study, the sample size, together with the low overall prevalence of autoimmune diseases in the population, did not allow us to examine which diseases are most frequently associated with other autoimmune diseases. However, this paper makes available an adequate control population for future clinical studies aimed at exploring the co-morbidity of specific pairs of autoimmune disease
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