Complex networks and data mining: toward a new perspective for the understanding of complex systems

Complex systems, i.e. systems composed of a large set of elements interacting in a non-linear way, are constantly found all around us. In the last decades, different approaches have been proposed toward their understanding, one of the most interesting being the Complex Network perspective. This legacy of the 18th century mathematical concepts proposed by Leonhard Euler is still current, and more and more relevant in real-world problems. In recent years, it has been demonstrated that network-based representations can yield relevant knowledge about complex systems. In spite of that, several problems have been detected, mainly related to the degree of subjectivity involved in the creation and evaluation of such network structures. In this Thesis, we propose addressing these problems by means of different data mining techniques, thus obtaining a novel hybrid approximation intermingling complex networks and data mining. Results indicate that such techniques can be effectively used to i) enable the creation of novel network representations, ii) reduce the dimensionality of analyzed systems by pre-selecting the most important elements, iii) describe complex networks, and iv) assist in the analysis of different network topologies. The soundness of such approach is validated through different validation cases drawn from actual biomedical problems, e.g. the diagnosis of cancer from tissue analysis, or the study of the dynamics of the brain under different neurological disorders.

Benefits & drawbacks of different means of interaction for placing objects above a video footage

Public Display Systems (PDS) increasingly have a greater presence in our cities. These systems provide information and advertising specifically tailored to audiences in spaces such as airports, train stations, and shopping centers. A large number of public displays are also being deployed for entertainment reasons. Sometimes designing and prototyping PDS come to be a laborious, complex and a costly task. This dissertation focuses on the design and evaluation of PDS at early development phases with the aim of facilitating low-effort, rapid design and the evaluation of interactive PDS. This study focuses on the IPED Toolkit. This tool proposes the design, prototype, and evaluation of public display systems, replicating real-world scenes in the lab. This research aims at identifying benefits and drawbacks on the use of different means to place overlays/virtual displays above a panoramic video footage, recorded at real-world locations. The means of interaction studied in this work are on the one hand the keyboard and mouse, and on the other hand the tablet with two different techniques of use. To carry out this study, an android application has been developed whose function is to allow users to interact with the IPED Toolkit using the tablet. Additionally, the toolkit has been modified and adapted to tablets by using different web technologies. Finally the users study makes a comparison about the different means of interaction.

Clinical practice guidelines in Portugal : quantitative and qualitative evaluation

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.

Quadratic programming versus second order con programming in portfolio optimization

Despite the extensive literature in finding new models to replace the Markowitz model or trying to increase the accuracy of its input estimations, there is less studies about the impact on the results of using different optimization algorithms. This paper aims to add some research to this field by comparing the performance of two optimization algorithms in drawing the Markowitz Efficient Frontier and in real world investment strategies. Second order cone programming is a faster algorithm, appears to be more efficient, but is impossible to assert which algorithm is better. Quadratic Programming often shows superior performance in real investment strategies.