884 resultados para probabilistic risk assessment
Resumo:
Le ricerche di carattere eustatico, mareografico, climatico, archeologico e geocronologico, sviluppatesi soprattutto nell’ultimo ventennio, hanno messo in evidenza che gran parte delle piane costiere italiane risulta soggetta al rischio di allagamento per ingressione marina dovuta alla risalita relativa del livello medio del mare. Tale rischio è la conseguenza dell’interazione tra la presenza di elementi antropici e fenomeni di diversa natura, spesso difficilmente discriminabili e quantificabili, caratterizzati da magnitudo e velocità molto diverse tra loro. Tra le cause preponderanti che determinano l’ingressione marina possono essere individuati alcuni fenomeni naturali, climatici e geologici, i quali risultano fortemente influenzati dalle attività umane soprattutto a partire dal XX secolo. Tra questi si individuano: - la risalita del livello del mare, principalmente come conseguenza del superamento dell’ultimo acme glaciale e dello scioglimento delle grandi calotte continentali; - la subsidenza. Vaste porzioni delle piane costiere italiane risultano soggette a fenomeni di subsidenza. In certe zone questa assume proporzioni notevoli: per la fascia costiera emiliano-romagnola si registrano ratei compresi tra 1 e 3 cm/anno. Tale subsidenza è spesso il risultato della sovrapposizione tra fenomeni naturali (neotettonica, costipamento di sedimenti, ecc.) e fenomeni indotti dall’uomo (emungimenti delle falde idriche, sfruttamento di giacimenti metaniferi, escavazione di materiali per l’edilizia, ecc.); - terreni ad elevato contenuto organico: la presenza di depositi fortemente costipabili può causare la depressione del piano di campagna come conseguenza di abbassamenti del livello della falda superficiale (per drenaggi, opere di bonifica, emungimenti), dello sviluppo dei processi di ossidazione e decomposizione nei terreni stessi, del costipamento di questi sotto il proprio peso, della carenza di nuovi apporti solidi conseguente alla diminuita frequenza delle esondazioni dei corsi d’acqua; - morfologia: tra i fattori di rischio rientra l’assetto morfologico della piana e, in particolare il tipo di costa (lidi, spiagge, cordoni dunari in smantellamento, ecc. ), la presenza di aree depresse o comunque vicine al livello del mare (fino a 1-2 m s.l.m.), le caratteristiche dei fondali antistanti (batimetria, profilo trasversale, granulometria dei sedimenti, barre sommerse, assenza di barriere biologiche, ecc.); - stato della linea di costa in termini di processi erosivi dovuti ad attività umane (urbanizzazione del litorale, prelievo inerti, costruzione di barriere, ecc.) o alle dinamiche idro-sedimentarie naturali cui risulta soggetta (correnti litoranee, apporti di materiale, ecc. ). Scopo del presente studio è quello di valutare la probabilità di ingressione del mare nel tratto costiero emiliano-romagnolo del Lido delle Nazioni, la velocità di propagazione del fronte d’onda, facendo riferimento allo schema idraulico del crollo di una diga su letto asciutto (problema di Riemann) basato sul metodo delle caratteristiche, e di modellare la propagazione dell’inondazione nell’entroterra, conseguente all’innalzamento del medio mare . Per simulare tale processo è stato utilizzato il complesso codice di calcolo bidimensionale Mike 21. La fase iniziale di tale lavoro ha comportato la raccolta ed elaborazione mediante sistema Arcgis dei dati LIDAR ed idrografici multibeam , grazie ai quali si è provveduto a ricostruire la topo-batimetria di dettaglio della zona esaminata. Nel primo capitolo è stato sviluppato il problema del cambiamento climatico globale in atto e della conseguente variazione del livello marino che, secondo quanto riportato dall’IPCC nel rapporto del 2007, dovrebbe aumentare al 2100 mediamente tra i 28 ed i 43 cm. Nel secondo e terzo capitolo è stata effettuata un’analisi bibliografica delle metodologie per la modellazione della propagazione delle onde a fronte ripido con particolare attenzione ai fenomeni di breaching delle difese rigide ed ambientali. Sono state studiate le fenomenologie che possono inficiare la stabilità dei rilevati arginali, realizzati sia in corrispondenza dei corsi d’acqua, sia in corrispondenza del mare, a discapito della protezione idraulica del territorio ovvero dell’incolumità fisica dell’uomo e dei territori in cui esso vive e produce. In un rilevato arginale, quale che sia la causa innescante la formazione di breccia, la generazione di un’onda di piena conseguente la rottura è sempre determinata da un’azione erosiva (seepage o overtopping) esercitata dall’acqua sui materiali sciolti costituenti il corpo del rilevato. Perciò gran parte dello studio in materia di brecce arginali è incentrato sulla ricostruzione di siffatti eventi di rottura. Nel quarto capitolo è stata calcolata la probabilità, in 5 anni, di avere un allagamento nella zona di interesse e la velocità di propagazione del fronte d’onda. Inoltre è stata effettuata un’analisi delle condizioni meteo marine attuali (clima ondoso, livelli del mare e correnti) al largo della costa emiliano-romagnola, le cui problematiche e linee di intervento per la difesa sono descritte nel quinto capitolo, con particolare riferimento alla costa ferrarese, oggetto negli ultimi anni di continui interventi antropici. Introdotto il sistema Gis e le sue caratteristiche, si è passati a descrivere le varie fasi che hanno permesso di avere in output il file delle coordinate x, y, z dei punti significativi della costa, indispensabili al fine della simulazione Mike 21, le cui proprietà sono sviluppate nel sesto capitolo.
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Long-term dietary exposures to lead in young children were calculated by combining food consumption data of 11 European countries categorised using harmonised broad food categories with occurrence data on lead from different Member States (pan-European approach). The results of the assessment in children living in the Netherlands were compared with a long-term lead intake assessment in the same group using Dutch lead concentration data and linking the consumption and concentration data at the highest possible level of detail. Exposures obtained with the pan-European approach were higher than the national exposure calculations. For both assessments cereals contributed most to the exposure. The lower dietary exposure in the national study was due to the use of lower lead concentrations and...
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Life Cycle Assessment (LCA) is a chain-oriented tool to evaluate the environment performance of products focussing on the entire life cycle of these products: from the extraction of resources, via manufacturing and use, to the final processing of the disposed products. Through all these stages consumption of resources and pollutant releases to air, water, soil are identified and quantified in Life Cycle Inventory (LCI) analysis. Subsequently to the LCI phase follows the Life Cycle Impact Assessment (LCIA) phase; that has the purpose to convert resource consumptions and pollutant releases in environmental impacts. The LCIA aims to model and to evaluate environmental issues, called impact categories. Several reports emphasises the importance of LCA in the field of ENMs. The ENMs offer enormous potential for the development of new products and application. There are however unanswered questions about the impacts of ENMs on human health and the environment. In the last decade the increasing production, use and consumption of nanoproducts, with a consequent release into the environment, has accentuated the obligation to ensure that potential risks are adequately understood to protect both human health and environment. Due to its holistic and comprehensive assessment, LCA is an essential tool evaluate, understand and manage the environmental and health effects of nanotechnology. The evaluation of health and environmental impacts of nanotechnologies, throughout the whole of their life-cycle by using LCA methodology. This is due to the lack of knowledge in relation to risk assessment. In fact, to date, the knowledge on human and environmental exposure to nanomaterials, such ENPs is limited. This bottleneck is reflected into LCA where characterisation models and consequently characterisation factors for ENPs are missed. The PhD project aims to assess limitations and challenges of the freshwater aquatic ecotoxicity potential evaluation in LCIA phase for ENPs and in particular nanoparticles as n-TiO2.
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In this study, some important aspects of the relationship between honey bees (Apis mellifera L.) and pesticides have been investigated. In the first part of the research, the effects of the exposure of honey bees to neonicotinoids and fipronil contaminated dusts were analyzed. In fact, considerable amounts of these pesticides, employed for maize seed dressing treatments, may be dispersed during the sowing operations, thus representing a way of intoxication for honey bees. In particular, a specific way of exposure to this pesticides formulation, the indirect contact, was taken into account. To this aim, we conducted different experimentations, in laboratory, in semi-field and in open field conditions in order to assess the effects on mortality, foraging behaviour, colony development and capacity of orientation. The real dispersal of contaminated dusts was previously assessed in specific filed trials. In the second part, the impact of various pesticides (chemical and biological) on honey bee biochemical-physiological changes, was evaluated. Different ways and durations of exposure to the tested products were also employed. Three experimentations were performed, combining Bt spores and deltamethrin, Bt spores and fipronil, difenoconazole and deltamethrin. Several important enzymes (GST, ALP, SOD, CAT, G6PDH, GAPDH) were selected in order to test the pesticides induced variations in their activity. In particular, these enzymes are involved in different pathways of detoxification, oxidative stress defence and energetic metabolism. The results showed a significant effect on mortality of neonicotinoids and fipronil contaminated dusts, both in laboratory and in semi-field trials. However, no effects were evidenced in honey bees orientation capacity. The analysis of different biochemical indicators highlighted some interesting physiological variations that can be linked to the pesticide exposure. We therefore stress the attention on the possibility of using such a methodology as a novel toxicity endpoint in environmental risk assessment.
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Falls are common and burdensome accidents among the elderly. About one third of the population aged 65 years or more experience at least one fall each year. Fall risk assessment is believed to be beneficial for fall prevention. This thesis is about prognostic tools for falls for community-dwelling older adults. We provide an overview of the state of the art. We then take different approaches: we propose a theoretical probabilistic model to investigate some properties of prognostic tools for falls; we present a tool whose parameters were derived from data of the literature; we train and test a data-driven prognostic tool. Finally, we present some preliminary results on prediction of falls through features extracted from wearable inertial sensors. Heterogeneity in validation results are expected from theoretical considerations and are observed from empirical data. Differences in studies design hinder comparability and collaborative research. According to the multifactorial etiology of falls, assessment on multiple risk factors is needed in order to achieve good predictive accuracy.
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Over the last decades the impact of natural disasters to the global environment is becoming more and more severe. The number of disasters has dramatically increased, as well as the cost to the global economy and the number of people affected. Among the natural disaster, flood catastrophes are considered to be the most costly, devastating, broad extent and frequent, because of the tremendous fatalities, injuries, property damage, economic and social disruption they cause to the humankind. In the last thirty years, the World has suffered from severe flooding and the huge impact of floods has caused hundreds of thousands of deaths, destruction of infrastructures, disruption of economic activity and the loss of property for worth billions of dollars. In this context, satellite remote sensing, along with Geographic Information Systems (GIS), has become a key tool in flood risk management analysis. Remote sensing for supporting various aspects of flood risk management was investigated in the present thesis. In particular, the research focused on the use of satellite images for flood mapping and monitoring, damage assessment and risk assessment. The contribution of satellite remote sensing for the delineation of flood prone zones, the identification of damaged areas and the development of hazard maps was explored referring to selected cases of study.
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Indicated prevention is currently regarded as the most promising strategy to attenuate, delay, or even avert psychosis. Existing criteria need improvement in terms of specificity and individual risk assessment to allow for better targeted and earlier interventions.
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Objective: To review the literature to identify and synthesize the evidence on risk factors for patient falls in geriatric rehabilitation hospital settings. Data sources: Eligible studies were systematically searched on 16 databases from inception to December 2010. Review methods: The search strategies used a combination of terms for rehabilitation hospital patients, falls, risk factors and older adults. Cross-sectional, cohort, case-control studies and randomized clinical trials (RCTs) published in English that investigated risks for falls among patients ≥65 years of age in rehabilitation hospital settings were included. Studies that investigated fall risk assessment tools, but did not investigate risk factors themselves or did not report a measure of risk (e.g. odds ratio, relative risk) were excluded. Results: A total of 2,824 references were identified; only eight articles concerning six studies met the inclusion criteria. In these, 1,924 geriatric rehabilitation patients were followed. The average age of the patients ranged from 77 to 83 years, the percentage of women ranged from 56% to 81%, and the percentage of fallers ranged from 15% to 54%. Two were case-control studies, two were RCTs and four were prospective cohort studies. Several intrinsic and extrinsic risk factors for falls were identified. Conclusion: Carpet flooring, vertigo, being an amputee, confusion, cognitive impairment, stroke, sleep disturbance, anticonvulsants, tranquilizers and antihypertensive medications, age between 71 and 80, previous falls, and need for transfer assistance are risk factors for geriatric patient falls in rehabilitation hospital settings.
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OBJECTIVES To compare health-related quality of life (QoL) in patients undergoing transcatheter aortic valve implantation via transapical access (TA TAVI) with patients undergoing surgical aortic valve replacement (SAVR). METHODS One hundred and forty-four high-risk patients referred for aortic valve replacement underwent TAVI screening and were assigned to either TA TAVI (n = 51, age 79.7 ± 9.2 years, logistic EuroSCORE 26.5 ± 16.1%, 51% males) or SAVR (n = 93, age 81.1 ± 5.3 years, logistic EuroSCORE 12.1 ± 9.3%, 42% males) by the interdisciplinary heart team. QoL was assessed using the Short Form 36 (SF-36) Health Survey Questionnaire and the Hospital Anxiety and Depression Scale. Furthermore, current living conditions and the degree of independence at home were evaluated. RESULTS Patients undergoing TA TAVI were at higher risk as assessed by EuroSCORE (26.5 ± 16 vs. 12.1 ± 9, P < 0.001) and STS score (6.7 ± 4 vs. 4.4 ± 3, P < 0.001) compared with SAVR patients. At the 30-day follow-up, the rate of mortality was similar and amounted to 7.8% for TA TAVI and 7.5% for SAVR patients and raised to 25.5% in TA TAVI and 18.3% in SAVR patients after a follow-up period of 15 ± 10 months. Assessment of QoL revealed no differences in terms of anxiety and depression between TA TAVI and SAVR patients. The SF-36 mental health metascore was similar in both groups (65.6 ± 19 vs. 68.8 ± 22, P = 0.29), while a significant difference was observed in the physical health metascore (49.7 ± 21 vs. 62.0 ± 21, P = 0.015). After adjustment for baseline characteristics, this difference disappeared. However, every added point in the preoperative risk assessment with the STS score decreased the SF-36 physical health dimension by two raw points at the follow-up assessment. CONCLUSIONS Selected high-risk patients undergoing TAVI by using a transapical access achieve similar clinical outcomes and QoL compared with patients undergoing SAVR. Increased STS scores predict worse QoL outcomes.
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Research suggests that mutans streptococci play an important role in cariogenesis in children but the usefulness of bacterial testing in risk assessment is unknown. Our objective was to summarize the literature assessing the association of mutans streptococci and dental caries in preschool children, (Pre)Medline (1966-2003), Embase (1980-2003), the Cochrane Register of Controlled Trials (2003, issue 3), and reference lists of included studies were searched. All abstracts found by the electronic searches (n = 981) were independently scrutinized by 2 reviewers. Minimal requirements for inclusion were assessment of preschool children without caries at baseline, reporting of mutans streptococci present in saliva or plaque at baseline and assessment of caries presence after a minimum of 6 months of follow-up. Participants' details, test methods, methodological characteristics and findings were extracted by one reviewer and cross-checked by another. Homogeneity was tested using chi2 tests. Results of plaque and saliva testing were pooled separately using a fixed effects model. Methodological quality of reports was low. Out of 9 studies included, data from 3 reports on plaque test assessment alone (n = 300) and from 4 reports on saliva test assessment alone (n = 451) were available for pooled analysis. The pooled risk ratio (95% CI) was 3.85 (2.48-5.96) in studies using plaque tests and 2.11 (1.47-3.02) in those using saliva testing. Presence of mutans streptococci, both in plaque or saliva of young caries-free children, appears to be associated with a considerable increase in caries risk. Lack of adjustment for potential confounders in the original studies, however, limits the extent to which interpretations for practice can be made.
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The development of a clinical decision tree based on knowledge about risks and reported outcomes of therapy is a necessity for successful planning and outcome of periodontal therapy. This requires a well-founded knowledge of the disease entity and a broad knowledge of how different risk conditions attribute to periodontitis. The infectious etiology, a complex immune response, and influence from a large number of co-factors are challenging conditions in clinical periodontal risk assessment. The difficult relationship between independent and dependent risk conditions paired with limited information on periodontitis prevalence adds to difficulties in periodontal risk assessment. The current information on periodontitis risk attributed to smoking habits, socio-economic conditions, general health and subjects' self-perception of health, is not comprehensive, and this contributes to limited success in periodontal risk assessment. New models for risk analysis have been advocated. Their utility for the estimation of periodontal risk assessment and prognosis should be tested. The present review addresses several of these issues associated with periodontal risk assessment.
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Large parts of the world are subjected to one or more natural hazards, such as earthquakes, tsunamis, landslides, tropical storms (hurricanes, cyclones and typhoons), costal inundation and flooding. Virtually the entire world is at risk of man-made hazards. In recent decades, rapid population growth and economic development in hazard-prone areas have greatly increased the potential of multiple hazards to cause damage and destruction of buildings, bridges, power plants, and other infrastructure; thus posing a grave danger to the community and disruption of economic and societal activities. Although an individual hazard is significant in many parts of the United States (U.S.), in certain areas more than one hazard may pose a threat to the constructed environment. In such areas, structural design and construction practices should address multiple hazards in an integrated manner to achieve structural performance that is consistent with owner expectations and general societal objectives. The growing interest and importance of multiple-hazard engineering has been recognized recently. This has spurred the evolution of multiple-hazard risk-assessment frameworks and development of design approaches which have paved way for future research towards sustainable construction of new and improved structures and retrofitting of the existing structures. This report provides a review of literature and the current state of practice for assessment, design and mitigation of the impact of multiple hazards on structural infrastructure. It also presents an overview of future research needs related to multiple-hazard performance of constructed facilities.
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Light-frame wood buildings are widely built in the United States (U.S.). Natural hazards cause huge losses to light-frame wood construction. This study proposes methodologies and a framework to evaluate the performance and risk of light-frame wood construction. Performance-based engineering (PBE) aims to ensure that a building achieves the desired performance objectives when subjected to hazard loads. In this study, the collapse risk of a typical one-story light-frame wood building is determined using the Incremental Dynamic Analysis method. The collapse risks of buildings at four sites in the Eastern, Western, and Central regions of U.S. are evaluated. Various sources of uncertainties are considered in the collapse risk assessment so that the influence of uncertainties on the collapse risk of lightframe wood construction is evaluated. The collapse risks of the same building subjected to maximum considered earthquakes at different seismic zones are found to be non-uniform. In certain areas in the U.S., the snow accumulation is significant and causes huge economic losses and threatens life safety. Limited study has been performed to investigate the snow hazard when combined with a seismic hazard. A Filtered Poisson Process (FPP) model is developed in this study, overcoming the shortcomings of the typically used Bernoulli model. The FPP model is validated by comparing the simulation results to weather records obtained from the National Climatic Data Center. The FPP model is applied in the proposed framework to assess the risk of a light-frame wood building subjected to combined snow and earthquake loads. The snow accumulation has a significant influence on the seismic losses of the building. The Bernoulli snow model underestimates the seismic loss of buildings in areas with snow accumulation. An object-oriented framework is proposed in this study to performrisk assessment for lightframe wood construction. For home owners and stake holders, risks in terms of economic losses is much easier to understand than engineering parameters (e.g., inter story drift). The proposed framework is used in two applications. One is to assess the loss of the building subjected to mainshock-aftershock sequences. Aftershock and downtime costs are found to be important factors in the assessment of seismic losses. The framework is also applied to a wood building in the state of Washington to assess the loss of the building subjected to combined earthquake and snow loads. The proposed framework is proven to be an appropriate tool for risk assessment of buildings subjected to multiple hazards. Limitations and future works are also identified.
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Meat and meat products can be contaminated with different species of bacteria resistant to various antimicrobials. The human health risk of a type of meat or meat product carry by emerging antimicrobial resistance depends on (i) the prevalence of contamination with resistant bacteria, (ii) the human health consequences of an infection with a specific bacterium resistant to a specific antimicrobial and (iii) the consumption volume of a specific product. The objective of this study was to compare the risk for consumers arising from their exposure to antibiotic resistant bacteria from meat of four different types (chicken, pork, beef and veal), distributed in four different product categories (fresh meat, frozen meat, dried raw meat products and heat-treated meat products). A semi-quantitative risk assessment model, evaluating each food chain step, was built in order to get an estimated score for the prevalence of Campylobacter spp., Enterococcus spp. and Escherichia coli in each product category. To assess human health impact, nine combinations of bacterial species and antimicrobial agents were considered based on a published risk profile. The combination of the prevalence at retail, the human health impact and the amount of meat or product consumed, provided the relative proportion of total risk attributed to each category of product, resulting in a high, medium or low human health risk. According to the results of the model, chicken (mostly fresh and frozen meat) contributed 6.7% of the overall risk in the highest category and pork (mostly fresh meat and dried raw meat products) contributed 4.0%. The contribution of beef and veal was of 0.4% and 0.1% respectively. The results were tested and discussed for single parameter changes of the model. This risk assessment was a useful tool for targeting antimicrobial resistance monitoring to those meat product categories where the expected risk for public health was greater.
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Starting with an overview on losses due to mountain hazards in the Russian Federation and the European Alps, the question is raised why a substantial number of events still are recorded—despite considerable efforts in hazard mitigation and risk reduction. The main reason for this paradox lies in a missing dynamic risk-based approach, and it is shown that these dynamics have different roots: firstly, neglecting climate change and systems dynamics, the development of hazard scenarios is based on the static approach of design events. Secondly, due to economic development and population dynamics, the elements at risk exposed are subject to spatial and temporal changes. These issues are discussed with respect to temporal and spatial demands. As a result, it is shown how risk is dynamic on a long-term and short-term scale, which has to be acknowledged in the risk concept if this concept is targeted at a sustainable development of mountain regions. A conceptual model is presented that can be used for dynamical risk assessment, and it is shown by different management strategies how this model may be converted into practice. Furthermore, the interconnectedness and interaction between hazard and risk are addressed in order to enhance prevention, the level of protection and the degree of preparedness.