16 resultados para Time-dependent Analysis


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Proceedings of the Information Technology Applications in Biomedicine, Ioannina - Epirus, Greece, October 26-28, 2006

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Proceedings of the Sixth Portuguese Conference on Bioemedical Engineering faro, Portugal

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Dissertação apresentada como requisito parcial para obtenção do grau de Mestre em Estatística e Gestão de Informação

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Thesis presented in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the subject of Electrical and Computer Engineering

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The last three decades have seen quite dramatic changes the way we modeled time dependent data. Linear processes have been in the center stage in modeling time series. As far as the second order properties are concerned, the theory and the methodology are very adequate.However, there are more and more evidences that linear models are not sufficiently flexible and rich enough for modeling purposes and that failure to account for non-linearities can be very misleading and have undesired consequences.

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Dissertação para obtenção do Grau de Mestre em Engenharia Informática

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Thesis submitted to the Instituto Superior de Estatística e Gestão de Informação da Universidade Nova de Lisboa in partial fulfillment of the requirements for the Degree of Doctor of Philosophy in Information Management – Geographic Information Systems

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Abstract Background: Nanotechnology has the potential to provide agriculture with new tools that may be used in the rapid detection and molecular treatment of diseases and enhancement of plant ability to absorb nutrients, among others. Data on nanoparticle toxicity in plants is largely heterogeneous with a diversity of physicochemical parameters reported, which difficult generalizations. Here a cell biology approach was used to evaluate the impact of Quantum Dots (QDs) nanocrystals on plant cells, including their effect on cell growth, cell viability, oxidative stress and ROS accumulation, besides their cytomobility. Results: A plant cell suspension culture of Medicago sativa was settled for the assessment of the impact of the addition of mercaptopropanoic acid coated CdSe/ZnS QDs. Cell growth was significantly reduced when 100 mM of mercaptopropanoic acid -QDs was added during the exponential growth phase, with less than 50% of the cells viable 72 hours after mercaptopropanoic acid -QDs addition. They were up taken by Medicago sativa cells and accumulated in the cytoplasm and nucleus as revealed by optical thin confocal imaging. As part of the cellular response to internalization, Medicago sativa cells were found to increase the production of Reactive Oxygen Species (ROS) in a dose and time dependent manner. Using the fluorescent dye H2DCFDA it was observable that mercaptopropanoic acid-QDs concentrations between 5-180 nM led to a progressive and linear increase of ROS accumulation. Conclusions: Our results showed that the extent of mercaptopropanoic acid coated CdSe/ZnS QDs cytotoxicity in plant cells is dependent upon a number of factors including QDs properties, dose and the environmental conditions of administration and that, for Medicago sativa cells, a safe range of 1-5 nM should not be exceeded for biological applications.

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Old timber structures may show significant variation in the cross section geometry along the same element, as a result of both construction methods and deterioration. As consequence, the definition of the geometric parameters in situ may be both time consuming and costly. This work presents the results of inspections carried out in different timber structures. Based on the obtained results, different simplified geometric models are proposed in order to efficiently model the geometry variations found. Probabilistic modelling techniques are also used to define safety parameters of existing timber structures, when subjected to dead and live loads, namely self-weight and wind actions. The parameters of the models have been defined as probabilistic variables, and safety of a selected case study was assessed using the Monte Carlo simulation technique. Assuming a target reliability index, a model was defined for both the residual cross section and the time dependent deterioration evolution. As a consequence, it was possible to compute probabilities of failure and reliability indices, as well as, time evolution deterioration curves for this structure. The results obtained provide a proposal for definition of the cross section geometric parameters of existing timber structures with different levels of decay, using a simplified probabilistic geometry model and considering a remaining capacity factor for the decayed areas. This model can be used for assessing the safety of the structure at present and for predicting future performance.

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Dissertação para obtenção do Grau de Mestre em Biotecnologia

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Dissertação para obtenção do Grau de Mestre em Engenharia Biomédica

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Dissertação para obtenção do Grau de Doutor em Engenharia Electrotécnica e de Computadores

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Dissertation submitted in partial fulfillment of the requirements for the Degree of Master of Science in Geospatial Technologies

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In the last few years, we have observed an exponential increasing of the information systems, and parking information is one more example of them. The needs of obtaining reliable and updated information of parking slots availability are very important in the goal of traffic reduction. Also parking slot prediction is a new topic that has already started to be applied. San Francisco in America and Santander in Spain are examples of such projects carried out to obtain this kind of information. The aim of this thesis is the study and evaluation of methodologies for parking slot prediction and the integration in a web application, where all kind of users will be able to know the current parking status and also future status according to parking model predictions. The source of the data is ancillary in this work but it needs to be understood anyway to understand the parking behaviour. Actually, there are many modelling techniques used for this purpose such as time series analysis, decision trees, neural networks and clustering. In this work, the author explains the best techniques at this work, analyzes the result and points out the advantages and disadvantages of each one. The model will learn the periodic and seasonal patterns of the parking status behaviour, and with this knowledge it can predict future status values given a date. The data used comes from the Smart Park Ontinyent and it is about parking occupancy status together with timestamps and it is stored in a database. After data acquisition, data analysis and pre-processing was needed for model implementations. The first test done was with the boosting ensemble classifier, employed over a set of decision trees, created with C5.0 algorithm from a set of training samples, to assign a prediction value to each object. In addition to the predictions, this work has got measurements error that indicates the reliability of the outcome predictions being correct. The second test was done using the function fitting seasonal exponential smoothing tbats model. Finally as the last test, it has been tried a model that is actually a combination of the previous two models, just to see the result of this combination. The results were quite good for all of them, having error averages of 6.2, 6.6 and 5.4 in vacancies predictions for the three models respectively. This means from a parking of 47 places a 10% average error in parking slot predictions. This result could be even better with longer data available. In order to make this kind of information visible and reachable from everyone having a device with internet connection, a web application was made for this purpose. Beside the data displaying, this application also offers different functions to improve the task of searching for parking. The new functions, apart from parking prediction, were: - Park distances from user location. It provides all the distances to user current location to the different parks in the city. - Geocoding. The service for matching a literal description or an address to a concrete location. - Geolocation. The service for positioning the user. - Parking list panel. This is not a service neither a function, is just a better visualization and better handling of the information.

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RESUMO: Introdução As normas de orientação clínica são ferramentas úteis na translação de conhecimentos desde a investigação para a prática clínica diária. Estratégias ativas de implementação de normas de orientação clínica requerem elevado esforço organizacional e financeiro. Quando os recursos são escassos, as estratégias passivas podem ser a única opção de disseminação. Desde 2011 a Direção Geral da Saúde publicou cento e cinquenta e nove normas de orientação clínica. Nesta Tese é feita uma avaliação do impacto que estratégias de disseminação de normas de orientação clínica têm no padrão de prescrição dos médicos e uma avaliação qualitativa do processo das normas de orientação clínica em Portugal. Métodos: O primeiro artigo é um estudo quasi experimental usando uma série de análises temporais interrompida para comparar os níveis observados e esperados de prescrição de inibidores da ciclooxigenasa-2, antes e depois da publicação da norma de orientação clínica sobre a utilização de anti-inflamatórios não esteroides. O segundo estudo é um artigo de opinião e debate no qual numa primeira parte contextualiza o processo das normas da Direcção Geral da Saúde, na segunda parte aponta virtudes e defeitos no processo e a terceira parte constitui uma contribuição com vista à melhoria do processo. Discussão A produção de normas de orientação clínica requer metodologia rigorosa e complexa. A literatura médica revela que a translação de conhecimento é uma tarefa árdua. Estratégias de implementação ativas requerem recursos financeiros e organizacionais sólidos. Estratégias de implementação passivas podem representar uma solução aceitável se os recursos financeiros e organizacionais escasseiam. Pouco é conhecido sobre a eficácia destas estratégias fora do contexto de investigação. Com esta Tese pretendo contribuir para a clarificação desta resposta, outros países e instituições podem ver utilidade nesta informação, bem como pretendo contribuir para a discussão e melhoria do processo das normas de orientação clínica em Portugal. ------------------ ABSTRACT: Introduction Clinical practice guidelines can help address the failure to translate research findings into clinical practice. Active clinical practice guidelines implementation strategies require active efforts from organizations and are resource and financially demanding. Passive implementation strategies may represent the only option if resources are scarce. Out of research environment, real world efficacy of passive implementation strategies is still undetermined. Since 2011 the Portuguese General Health Directorate published one hundred and fifty nine guidelines. In this Thesis I evaluate the impact of passive dissemination of clinical practice guideline in clinician’s prescription behavior and review, from a qualitative point of view, the Portuguese clinical practice guideline process. Methods The first study is a quasi-experimental study using a retrospective interrupted time-series analysis design to compare the observed and expected prescription of cyclooxygenase-2 before and after the non steroidal antiinflammatory guideline publication. The second study is an opinion and debate article in which I firstly review the General Health Directorate guideline process. The second part states positive and negative aspects in the process and the third part is a contribution aimed at improving the process in the future. Discussion Clinical practice guidelines production demands a rigorous and complex methodology. medical iterature reveals that knowledge translation is a difficult task. Active implementation strategies demand solid financial and organizational resources. Passive implementation strategies may represent an acceptable solution if financial and organizational resources are scarce. Little is known about the efficacy of these strategies out of the research context. With this Thesis I intend to contribute to clarify this question, other countries and institutions with similar conditions may find this information useful, and also to contribute for the discussion and general improvement of national clinical practice guidelines process.