46 research outputs found

    Costo sinistri aggregato e strutture di dipendenza: extreme value theory, modelli simulativi e Fast Fourier Transform

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    La corretta determinazione della distribuzione di probabilit脿 del costo sinistri aggregato ha un ruolo fondamentale nell鈥檃nalisi della rischiosit脿 e della solvibilit脿 di una compagnia di assicurazione e la letteratura ha sviluppato, e continua a farlo, diverse modellistiche complesse che consentono di analizzare i rischi assicurativi in modo integrato, individuando eventuali dipendenze tra gli elementi caratterizzanti il profilo di rischio dell鈥檃zienda. Alcune delle tecniche concernenti la modellizzazione del costo sinistri aggregato sono proprio l鈥檕ggetto principale del presente lavoro di tesi, in cui particolare importanza 猫 data al concetto di funzione Copula ed alla Fast Fourier Transform

    Din谩mica temporal de nutrientes, clorofila a y par谩metros de calidad del agua en la Laguna de Venecia

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    Since 1997, CNR-ISMAR has been collecting monthly hydrochemical and phytoplankton data in the northern and central basins of the Lagoon of Venice. The data have been part of the International Long-Term Ecosystem Research (LTER) database since 2007, helping to fill a gap in lagoon environmental studies. Analysing our time series (1998-2017), we were able to observe a rise in water temperature due to climate trends, a reduction in trophic status mainly due to the lower input of inorganic dissolved nitrogen nutrients and an increase in transparency and dissolved oxygen related to the increased biomass of macrophytes (macroalgae and seagrasses). Finally, a reduction in phytoplankton biomass and an accompanying increase in seagrass and macroalgal cover were observed. Present and future studies will help to evaluate the ways in which the Lagoon of Venice ecosystem responds to anthropogenic pressures and global climate change.Desde 1997, el CNR ISMAR ha recopilado datos mensuales de hidroqu铆mica y fitoplancton en las zonas del norte y centro de la Laguna de Venecia. Desde el 2007 los datos hacen parte de la base de datos LTER (International Long-Term Ecosystem Research), ayudando a llenar la falta de datos en los estudios ambientales de la Laguna. Analizando nuestra serie hist贸rica (1998-2017), pudimos observar un aumento de la temperatura del agua debido a las tendencias clim谩ticas, una reducci贸n del estado tr贸fico debido principalmente al menor suministro de nutrientes inorg谩nicos de nitr贸geno disuelto y un aumento de la transparencia y del ox铆geno disuelto relacionado al aumento de la biomasa de macr贸fitas (macroalgas y faner贸颅gamas). Por 煤ltimo, se observ贸 una reducci贸n de la biomasa del fitoplancton y al mismo tiempo un aumento de faner贸gamas y macroalgas. Los actuales y futuros estudios ayudar谩n a evaluar las formas en el cual el ecosistema de la Laguna de Venecia responder谩 a las presiones antropog茅nicas y al cambio clim谩tico global

    B煤squeda de patrones en la comunidad fitoplanct贸nica de una laguna micromareal (Laguna de Venecia): evidencias en diez a帽os de observaci贸n

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    By analysing a ten-year series (1998-2007) of data on hydrochemical properties, phytoplankton abundance and species composition in the Venice Lagoon, we identified i) the average annual phytoplankton biomass cycle, mainly unimodal and fairly well tuned with the fluctuations in temperature and irradiance and (ii) the seasonal succession of the most important species, allowing us to construct a 鈥減hytoplankton calendar鈥. Phytoplankton biomass was significantly lower in the second half of the ten-year period (2003-2007) than in the first half (1998-2002).A trav茅s del an谩lisis de propiedades hidroqu铆micas, abundancia fitoplanct贸nica y composici贸n de especies, en series de diez a帽os (1998-2007), en la laguna de Venecia, se han identificado: i) Un promedio anual del ciclo de la biomasa prevalentemente de forma unimodal y bien sintonizada con las fluctuaciones de temperatura e irradiaci贸n; ii) Una composici贸n cualitativa del fitoplancton que nos ha permitido realizar un 鈥渃alendario del fitoplancton鈥; iii) Un decrecimiento en los 煤ltimos 5 a帽os (2003-2007), de la biomasa con respecto a los 5 primeros a帽os (1998-2003)

    Dissolved Inorganic Nutrients in the Western Mediterranean Sea (2004-2017)

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    Abstract. Long-term time-series are a fundamental prerequisite to understand and detect climate shifts and trends. Understanding the complex interplay of changing ocean variables and the biological implication for marine ecosystems requires extensive data collection for monitoring and hypothesis testing and validation of modelling products. In marginal seas, such as Mediterranean Sea, there are still monitoring gaps, both in time and in space. To contribute filling these gaps, an extensive dataset of dissolved inorganic nutrients profiles (nitrate, NO3; phosphate, PO4 ; and silicate, SiO2) have been collected between 2004 and 2017 in the Western Mediterranean Sea and subjected to quality control techniques to provide to the scientific community a publicly available, long-term, quality controlled, internally consistent biogeochemical data product. The database includes 27 870 stations of dissolved inorganic nutrients sampled during 24 cruises, including temperature and salinity. Details of the quality control (primary and secondary quality control) applied are reported. The data are available in PANGAEA (https://doi.pangaea.de/10.1594/PANGAEA.904172, Belgacem et al. 2019) Keywords: Mediterranean Sea, Dissolved Inorganic Nutrient, biogeochemistr

    Natural or anthropogenic variability? A long-term pattern of the zooplankton communities in an ever-changing transitional ecosystem

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    The Venice Lagoon is an important site belonging to the Italian Long-Term Ecological Research Network (LTER). Alongside with the increasing trend of water temperature and the relevant morphological changes, in recent years, the resident zooplankton populations have also continued to cope with the colonization by alien species, particularly the strong competitor Mnemiopsis leidyi. In this work, we compared the dynamics of the lagoon zooplankton over a period of 20 years. The physical and biological signals are analyzed and compared to evaluate the hypothesis that a slow shift in the environmental balance of the site, such as temperature increase, sea level rise (hereafter called 鈥渕arinization鈥), and competition between species, is contributing to trigger a drift in the internal equilibrium of the resident core zooplankton. Though the copepod community does not seem to have changed its state, some important modifications of structure and assembly mechanisms have already been observed. The extension of the marine influence within the lagoon has compressed the spatial gradients of the habitat and created a greater segregation of the niches available to some typically estuarine taxa and broadened and strengthened the interactions between marine species

    Thoracoscopic resection of a paraaortic bronchogenic cyst

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    Bronchogenic mediastinal cysts (BMC) represent 18% of primitive mediastinal tumors and the most frequent cystic lesions in this area. Nowadays, BMC are usually treated by VATS. However, the presence of major adhesions to vital structures is often considered as an unfavourable condition for thoracoscopic treatment. The authors report the thoracoscopic treatment of a BMC having dense adhesions to the aortic arch. Diagnosis and surgical treatment is described. Review of the literature and surgical options on this topic are discussed

    Surgical management of pulmonary inflammatory pseudotumors: A single center experience

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    <p>Abstract</p> <p>Background</p> <p>The pulmonary inflammatory pseudotumor (PIP) is a rare disease. It is still debated whether it represents an inflammatory lesion characterized by uncontrolled cell growth or a true neoplasm. PIP is characterized by a cellular polymorphism.</p> <p>Methods</p> <p>We retrospectively analyzed 8 patients with PIP treated by surgery between 2001 and 2009. Preoperative thoracic computed tomography (CT) scan was performed in all cases. All patients underwent preoperative bronchoscopy with washing and brushing and/or transbronchial biopsy and preoperative cytology examination</p> <p>Results</p> <p>There were 5 men and 3 women, aged between 38 and 69 years (mean of 58 years). 3 patients (37%) were asymptomatic. The others had symptoms characterized by chest pain, shortness of breath and persistent cough or hemoptysis. 5 patients had neutrophilic leucocytosis. CT scan demonstrated solitary nodules (maximum diameter <3 cm) in 5 patients (62%) and lung masses (maximum diameter >3 cm) in 3 patients (37%). In 2 patients there were signs of pleural infiltration. Distant lesions were excluded in all cases. A preoperative histology examination failed to reach a definitive diagnosis in all patients. At surgery, we performed two lobectomies, one segmentectomy and five wedge resections, these being performed with videothoracoscopy (VATS), except for one patient where open surgery was used. Complete tumor resection was obtained in all patients. According to the Matsubara classification, there were 2 cases of organizing pneumonia, 5 cases of fibrous histiocytoma and one case of lymphoplasmacytoma. All patients were discharged alive from hospital between 4 and 7 days after surgery. At follow-up CT scan performed annually (range 11 to 112 months) (mean 58 months), there were no residual lesions, neither local nor distant recurrences.</p> <p>Conclusions</p> <p>PIP is a rare disease. Many synonyms have been used for this disease, usually in relation to the most represented cell type. The true incidence is unclear. Preoperative diagnosis is difficult to reach, despite performing a bronchoscopy or a transparietal needle aspiration. Different classifications have been proposed for PIP. Either medical, radiation or surgical therapy has been used for PIP. Whenever possible, surgery should be considered the standard treatment. Complete surgical resection is advocated to prevent recurrence.</p

    The Italian long-term ecosystem research (LTER-Italy) network: results, opportunities, and challenges for coastal transitional ecosystems

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    1 - The Long-Term Ecosystem Research (LTER) network, now a global reality, was founded on a combination of long-term ecological studies, short-term experiments, and comparisons among sites and eco-domains. 2 - The LTER-Italy network was officially established as a formal member of the LTER international network in 2006, following a wider on-going process in Europe; it currently consists of 22 sites representing the main ecosystem typologies of Italy. Four coastal transitional ecosystem sites are included in the LTER-Italy network: on the northern Peninsula, these include the Venice Lagoon and the lagoons of the Po River Delta, which are characterized by a temperate climate and the influence of tides; and in the southern sector, these include the coastal ecosystems of Sardinia and the Mar Piccolo of Taranto, which are characterized by a Mediterranean climate and the absence of sensible tides. 3 - In this paper, we present and discuss three main issues: the LTER-International and LTER-Europe context, emphasising the most practical issues and activities that must be addressed for the effective organization and maintenance of LTER networks; the history, structure, and perspectives of the national LTER-Italy network; and the opportunities, strengths, and weaknesses related to participation of the LTER-Italy network in the study of coastal transitional ecosystems

    Congenital hip dysplasia treated by total hip arthroplasty using cementless tapered stem in patients younger than 50聽years old: results after 12-years follow-up

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    Background Congenital hip dysplasia may lead to severe acetabular and femoral abnormalities that can make total hip arthroplasty a challenging procedure. We assessed a series of patients affected by developmental hip dysplasia treated with total hip arthroplasty using cementless tapered stem and here we report the outcomes at long-term follow-up. Materials and methods Twenty-eight patients (24 women and 4 men) aged between 44 and 50 years (mean 47 years) were observed. Clinical evaluation was rated with the Harris Hip Score. Radiographic evaluation consisted in standard anteroposterior and axial view radiographs of the hip. According to Crowe鈥檚 classification, 16 hips presented dysplasia grade 1, 14 grade 2, and 4 grade 3. All patients were treated with total hip arthroplasty using a cementless tapered stem (Wagner Cone Prosthesis). Six patients were operated bilaterally, with a totally of 34 hips operated. After surgery, the patients were clinically and radiographically checked at 3, 6, and 12 months and yearly thereafter until an average follow-up of 12 years (range 10鈥14 years). Results Average Harris Hip Score was 56 卤 9 (range 45鈥69) preoperatively, 90 卤 9 (range 81鈥100) 12 months after surgery, and 91 卤 8 (range 83鈥100) at last follow-up. Radiographic evaluation demonstrated excellent osteointegration of the implants. Signs of bone resorption were present in 6 hips, nevertheless no evidence of loosening was observed and none of the implants has been revised. Conclusions Even in dysplasic femur, the tapered stem allowed adequate stability and orientation of the implant. We consider tapered stem a suitable option for total hip arthroplasty in developmental hip dysplasia, also in case of young patients, thanks to the favourable long-term results
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