45 research outputs found

    Evaluations of User-Driven Ontology Summarization

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    Ontology Summarization has been found useful to facilitate ontology engineering tasks in a number of different ways. Recently, it has been recognised as a means to facilitate ontology understanding and then support tasks like ontology reuse in ontology construction. Among the works in literature, not only distinctive methods are used to summarize ontology, also different measures are deployed to evaluate the summarization results. Without a set of common evaluation measures in place, it is not possible to compare the performance and therefore judge the effectiveness of those summarization methods. In this paper, we investigate the applicability of the evaluation measures from ontology evaluation and summary evaluation domain for ontology summary evaluation. Based on those measures, we evaluate the performances of the existing user-driven ontology summarization approaches

    Quantification of depth of anesthesia by nonlinear time series analysis of brain electrical activity

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    We investigate several quantifiers of the electroencephalogram (EEG) signal with respect to their ability to indicate depth of anesthesia. For 17 patients anesthetized with Sevoflurane, three established measures (two spectral and one based on the bispectrum), as well as a phase space based nonlinear correlation index were computed from consecutive EEG epochs. In absence of an independent way to determine anesthesia depth, the standard was derived from measured blood plasma concentrations of the anesthetic via a pharmacokinetic/pharmacodynamic model for the estimated effective brain concentration of Sevoflurane. In most patients, the highest correlation is observed for the nonlinear correlation index D*. In contrast to spectral measures, D* is found to decrease monotonically with increasing (estimated) depth of anesthesia, even when a "burst-suppression" pattern occurs in the EEG. The findings show the potential for applications of concepts derived from the theory of nonlinear dynamics, even if little can be assumed about the process under investigation.Comment: 7 pages, 5 figure
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