Pedro A. C. Sousa

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The dynamic and unstable nature observed in real world applications influences learning systems through changes in data, context and resource availability. Data stream mining systems must be aware and adapt to such changes so that incoming data can continuously be classified with high accuracy. Ensemble approaches have been shown successful in dealing with(More)
An emerging trend in the engineering of complex systems is the use of component integration frameworks. Such a framework prescribes an architectural design that permits exible composition of thirdparty components into applications. A good example is Sun Microsystems' Enterprise JavaBeans (EJB) framework, which supports objectoriented, distributed,(More)
The increasing power of computer technology does not dispense with the need to extract meaningful information out of data sets of ever growing size, and indeed typically exacerbates the complexity of this task. To tackle this general problem, two methods have emerged, at chronologically different times, that are now commonly used in the scientific(More)
The problem of recurring concepts in data stream classification is a special case of concept drift where concepts may reappear. Although several existing methods are able to learn in the presence of concept drift, few consider contextual information when tracking recurring concepts. Nevertheless, in many real-world scenarios context information is available(More)
Development (FLAD). The views and conclusions contained in this document are those of the author and should not be interpreted as representing the official policies, either expressed or implied, of any sponsoring institution, the U.S. government or any other entity. Abstract Advances in computing and networking are prompting users to change their(More)
Mobile activity recognition focuses on inferring the current activities of a mobile user by leveraging the sensory data that is available on today's smart phones. The state of the art in mobile activity recognition uses traditional classification techniques. Thus, the learning process typically involves: i) collection of labelled sensory data that is(More)
AIMS Pulmonary vein isolation is the mainstay of treatment in catheter ablation of paroxysmal atrial fibrillation (AF). Cryoballoon ablation has been introduced more recently than radiofrequency ablation, the standard technique in most centres. Pulmonary veins frequently display anatomical variants, which may compromise the results of cryoballoon ablation.(More)
We introduce a novel method to represent time independent, scalar data sets as complex networks. We apply our method to investigate gene expression in the response to osmotic stress of Arabidopsis thaliana. In the proposed network representation, the most important genes for the plant response turn out to be the nodes with highest centrality in(More)
The prevalence of atrial fibrillation (AF) is increased in hyperthyroidism. The degree to which thyroid hormones affect the outcomes of left atrial (LA) ablation is still unclear. From September 2010 to September 2013, 1,095 patients who underwent LA ablation (59.7% paroxysmal AF, 32.3% persistent AF, and 8.0% LA tachycardia) had their serum(More)