Os atuais avanços na área das Tecnologias da Informação e da Comunicação (TIC) estão mudando a Educação, com a disponibilização de sistemas educativos para apoiar as atividades no processo de ensino e de aprendizagem. Embora o tópico de combinatória seja relevante para o ensino médio e para os cursos de Ciências Exatas, este tópico tem sido desconsiderado nos avanços da Informática na Educação, principalmente ao se considerar o uso de ambientes de aprendizagem via Web. Atualmente, o iComb é, no melhor de nosso conhecimento, o único sistema Web integrável a tais ambientes. Ele é um Módulo de Aprendizagem Interativa (iMA) integrável ao Sistema Gerenciador de Cursos (SGC) Moodle, por meio do plugin iTarefa. O iComb oferece atividades de autoria de exercícios, bem como, sua avaliação automática. No entanto, considerando sua usabilidade, foram detectados alguns problemas na interface. O foco deste trabalho está relacionado ao reprojeto do sistema iComb e seu impacto na aprendizagem de combinatória. Para a reconstrução do iComb adotou-se o método de design de interação, buscando-se a participação efetiva de usuários finais do sistema, em todas as atividades desse processo, com (i) sessões de teste de usabilidade utilizando a versão Java do iComb para identificar problemas e guiar o redesenho do sistema, e (ii) prototipagem e avaliação da interface do sistema redesenhado. Esse processo permitiu implementar uma nova versão do iComb utilizando tecnologias associadas ao HTML5, que será brevemente disponibilizado como software livre. / Current advances in Information and Communication Technologies (ICT) are changing Education with delivering software to support learning/teaching activities. Although being relevant for Science, Technology, Engineering, and Mathematics (STEM) courses, Combinatorial Analysis is almost disregarded in these advances, mostly if we consider their integration with earning Management Systems. Currently, iComb is, at the best of our knowledge, the only system with such a possibility. It is an interactive Learning Module (iLM) that can be integrated to Moodle, through the iAssign plugin. iComb provides authoring activities as well as their automatic assessment. Nevertheless, considering the system usability, several interaction problems were detected during sessions with teachers and students. In this work it is described the process of redesigning the iComb system by adopting Interactive Design, to conduct controlled sessions of system use for (i) identifying usability issues for guiding the system redesign; and (ii) prototyping and evaluate the redesigned system interface, with end-users. This process allowed to implement new version of iComb using HTML5 related technologies that will be sooner available as free software, in order to reach a larger audience. Preliminary results on the interface evaluation indicate that both students and teachers felt more comfortable using the new interface of iComb and found it easier to execute common tasks.

Os atuais avanços na área das Tecnologias da Informação e da Comunicação (TIC) estão mudando a Educação, com a disponibilização de sistemas educativos para apoiar as atividades no processo de ensino e de aprendizagem. Embora o tópico de combinatória seja relevante para o ensino médio e para os cursos de Ciências Exatas, este tópico tem sido desconsiderado nos avanços da Informática na Educação, principalmente ao se considerar o uso de ambientes de aprendizagem via Web. Atualmente, o iComb é, no melhor de nosso conhecimento, o único sistema Web integrável a tais ambientes. Ele é um Módulo de Aprendizagem Interativa (iMA) integrável ao Sistema Gerenciador de Cursos (SGC) Moodle, por meio do plugin iTarefa. O iComb oferece atividades de autoria de exercícios, bem como, sua avaliação automática. No entanto, considerando sua usabilidade, foram detectados alguns problemas na interface. O foco deste trabalho está relacionado ao reprojeto do sistema iComb e seu impacto na aprendizagem de combinatória. Para a reconstrução do iComb adotou-se o método de design de interação, buscando-se a participação efetiva de usuários finais do sistema, em todas as atividades desse processo, com (i) sessões de teste de usabilidade utilizando a versão Java do iComb para identificar problemas e guiar o redesenho do sistema, e (ii) prototipagem e avaliação da interface do sistema redesenhado. Esse processo permitiu implementar uma nova versão do iComb utilizando tecnologias associadas ao HTML5, que será brevemente disponibilizado como software livre. / Current advances in Information and Communication Technologies (ICT) are changing Education with delivering software to support learning/teaching activities. Although being relevant for Science, Technology, Engineering, and Mathematics (STEM) courses, Combinatorial Analysis is almost disregarded in these advances, mostly if we consider their integration with earning Management Systems. Currently, iComb is, at the best of our knowledge, the only system with such a possibility. It is an interactive Learning Module (iLM) that can be integrated to Moodle, through the iAssign plugin. iComb provides authoring activities as well as their automatic assessment. Nevertheless, considering the system usability, several interaction problems were detected during sessions with teachers and students. In this work it is described the process of redesigning the iComb system by adopting Interactive Design, to conduct controlled sessions of system use for (i) identifying usability issues for guiding the system redesign; and (ii) prototyping and evaluate the redesigned system interface, with end-users. This process allowed to implement new version of iComb using HTML5 related technologies that will be sooner available as free software, in order to reach a larger audience. Preliminary results on the interface evaluation indicate that both students and teachers felt more comfortable using the new interface of iComb and found it easier to execute common tasks.

Pas de résumé en français / Malaria is a devastating global health problem that affected 219 million people and caused 660,000 deaths in 2010. Inaccurate estimation of the level of infection may have adverse clinical and therapeutic implications for patients, and for epidemiological endpoint measurements. The level of infection, expressed as the parasite density (PD), is classically defined as the number of asexual parasites relative to a microliter of blood. Microscopy of Giemsa-stained thick blood smears (TBSs) is the gold standard for parasite enumeration. Parasites are counted in a predetermined number of high-power fields (HPFs) or against a fixed number of leukocytes. PD estimation methods usually involve threshold values; either the number of leukocytes counted or the number of HPFs read. Most of these methods assume that (1) the distribution of the thickness of the TBS, and hence the distribution of parasites and leukocytes within the TBS, is homogeneous; and that (2) parasites and leukocytes are evenly distributed in TBSs, and thus can be modeled through a Poisson-distribution. The violation of these assumptions commonly results in overdispersion. Firstly, we studied the statistical properties (mean error, coefficient of variation, false negative rates) of PD estimators of commonly used threshold-based counting techniques and assessed the influence of the thresholds on the cost-effectiveness of these methods. Secondly, we constituted and published the first dataset on parasite and leukocyte counts per HPF. Two sources of overdispersion in data were investigated: latent heterogeneity and spatial dependence. We accounted for unobserved heterogeneity in data by considering more flexible models that allow for overdispersion. Of particular interest were the negative binomial model (NB) and mixture models. The dependent structure in data was modeled with hidden Markov models (HMMs). We found evidence that assumptions (1) and (2) are inconsistent with parasite and leukocyte distributions. The NB-HMM is the closest model to the unknown distribution that generates the data. Finally, we devised a reduced reading procedure of the PD that aims to a better operational optimization and a practical assessing of the heterogeneity in the distribution of parasites and leukocytes in TBSs. A patent application process has been launched and a prototype development of the counter is in process.

Malaria is a devastating global health problem that affected 219 million people and caused 660,000 deaths in 2010. Inaccurate estimation of the level of infection may have adverse clinical and therapeutic implications for patients, and for epidemiological endpoint measurements. The level of infection, expressed as the parasite density (PD), is classically defined as the number of asexual parasites relative to a microliter of blood. Microscopy of Giemsa-stained thick blood smears (TBSs) is the gold standard for parasite enumeration. Parasites are counted in a predetermined number of high-power fields (HPFs) or against a fixed number of leukocytes. PD estimation methods usually involve threshold values; either the number of leukocytes counted or the number of HPFs read. Most of these methods assume that (1) the distribution of the thickness of the TBS, and hence the distribution of parasites and leukocytes within the TBS, is homogeneous; and that (2) parasites and leukocytes are evenly distributed in TBSs, and thus can be modeled through a Poisson-distribution. The violation of these assumptions commonly results in overdispersion. Firstly, we studied the statistical properties (mean error, coefficient of variation, false negative rates) of PD estimators of commonly used threshold-based counting techniques and assessed the influence of the thresholds on the cost-effectiveness of these methods. Secondly, we constituted and published the first dataset on parasite and leukocyte counts per HPF. Two sources of overdispersion in data were investigated: latent heterogeneity and spatial dependence. We accounted for unobserved heterogeneity in data by considering more flexible models that allow for overdispersion. Of particular interest were the negative binomial model (NB) and mixture models. The dependent structure in data was modeled with hidden Markov models (HMMs). We found evidence that assumptions (1) and (2) are inconsistent with parasite and leukocyte distributions. The NB-HMM is the closest model to the unknown distribution that generates the data. Finally, we devised a reduced reading procedure of the PD that aims to a better operational optimization and a practical assessing of the heterogeneity in the distribution of parasites and leukocytes in TBSs. A patent application process has been launched and a prototype development of the counter is in process.