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Cognitive studies of clinical comprehension reveal that expert clinicians are distinguished by their superior ability to recognize meaningful patterns of data in clinical narratives. For example, in psychiatry, the findings of hallucinations and delusions suggest the subdiagnostic hypothesis of a psychotic episode, which in turn suggests several diagnoses, including schizophrenia. This dissertation describes the design and evaluation of a system that aims to simulate an important aspect of expert comprehension: the ability to recognize clusters of findings that support sub-diagnostic hypotheses. The broad range of content in psychiatric narrative presents a formidable barrier to achieving this goal, as it contains general concepts and descriptions of the subjective experience of psychiatric patients in addition to general medical and psychiatric concepts. Lexically driven language processing of such narrative would require the exhaustive predefinition of every concept likely to be encountered. In contrast, Latent Semantic Analysis (LSA) is a corpus-based statistical model of language that learns human-like estimates of the similarity between concepts from a text corpus. LSA is adapted to create trainable models of sub-diagnostic hypotheses, which are then used to recognize related elements in psychiatric discharge summary text. The system is evaluated against an independently annotated set of psychiatric discharge summaries. System-rater agreement approached rater-rater agreement, providing support for the practical application of vector-based models of meaning in domains with broad conceptual territory. Other applications and implications are discussed, including the presentation of a prototype user interface designed to enhance novice comprehension of psychiatric discourse.

[pt] Os últimos anos testemunharam o uso crescente de dispositivos que rastreiam objetos móveis: equipamentos com GPS e telefones móveis, veículos ou outros sensores da Internet das Coisas, além de dados de localização de check-ins de redes sociais. Estes dados de mobilidade são representados como trajetórias, e armazenam a sequência de posições de um objeto móvel. Porém, estas sequências representam somente os dados de posição originais, que precisam ser semanticamente enriquecidos para permitir tarefas de análise e apoiar um entendimento profundo sobre o comportamento do movimento. Um outro espaço de dados global sem precedentes tem crescido rapidamente, a Web de Dados, graças à iniciativa de Dados Interligados. Estes dados semânticos ricos e livremente disponíveis fornecem uma nova maneira de enriquecer dados de trajetória. Esta tese apresenta contribuições para os desafios que surgem considerando este cenário. Em primeiro lugar, a tese investiga como dados de trajetória podem se beneficiar da iniciativa de dados interligados, guiando todo o processo de enriquecimento semântico utilizando fontes de dados externas. Em segundo lugar, aborda o tópico de computação de similaridade entre entidades representadas como dados interligados com o objetivo de computar a similaridade entre trajetórias semanticamente enriquecidas. A novidade da abordagem apresentada nesta tese consiste em considerar as características relevantes das entidades como listas ranqueadas. Por último, a tese aborda a computação da similaridade entre trajetórias enriquecidas comparando a similaridade entre todas as entidades representadas como dados interligados que representam as trajetórias enriquecidas. / [en] The last years witnessed a growing number of devices that track moving objects: personal GPS equipped devices and GSM mobile phones, vehicles or other sensors from the Internet of Things but also the location data deriving from the Social Networks check-ins. These mobility data are represented as trajectories, recording the sequence of locations of the moving object. However, these sequences only represent the raw location data and they need to be semantically enriched to be meaningful in the analysis tasks and to support a deep understanding of the movement behavior. Another unprecedented global space that is also growing at a fast pace is the Web of Data, thanks to the emergence of the Linked Data initiative. These freely available semantic rich datasets provide a novel way to enhance trajectory data. This thesis presents a contribution to the many challenges that arise from this scenario. First, it investigates how trajectory data may benefit from the Linked Data Initiative by guiding the whole trajectory enrichment process with the use of external datasets. Then, it addresses the pivotal topic of the similarity computation between Linked Data entities with the final objective of computing the similarity between semantically enriched trajectories. The novelty of our approach is that the thesis considers the relevant entity features as a ranked list. Finally, the thesis targets the computation of the similarity between enriched trajectories by comparing the similarity of the Linked Data entities that represent the enriched trajectories.