Coleção de Artigos Acadêmicos
URI permanente para esta coleçãohttps://repositorio.insper.edu.br/handle/11224/3227
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338 resultados
Resultados da Pesquisa
Artigo Científico A privacidade e o mercado de dados pessoais(2016) Silveira, Sergio Amadeu; RODOLFO DA SILVA AVELINO; Souza, JoyceO artigo apresenta a estrutura e a dinâmica do mercado de dados pessoais. Mostra a dimensão econômica do dado pessoal para a economia da informação. Apresenta as quatro camadas do mercado de dados: a coleta e armazenamento de informações; o processamento e a mineração de dados; a análise e a formação de amostras; e a modulação. Essas camadas se articulam e se misturam dependendo da organização das empresas que integram esse mercado. O artigo mostra ainda os elementos do mercado de dados no Brasil a partir de entrevistas realizadas com seus operadores. Por fim, indica a relevância do direito à privacidade para impor limites às atividades da economia da interceptação de dados.Artigo Científico Identification of segregated regions in the functional brain connectome of autistic patients by a combination of fuzzy spectral clustering and entropy analysis(2016) Sato, João Ricardo; Balardin, Joana; MACIEL CALEBE VIDAL; André FujitaBackground: Several neuroimaging studies support the model of abnormal development of brain connectivity in patients with autism-spectrum disorders (ASD). In this study, we aimed to test the hypothesis of reduced functional network segregation in autistic patients compared with controls. Methods: Functional MRI data from children acquired under a resting-state protocol (Autism Brain Imaging Data Exchange [ABIDE]) were submitted to both fuzzy spectral clustering (FSC) with entropy analysis and graph modularity analysis. Results: We included data from 814 children in our analysis. We identified 5 regions of interest comprising the motor, temporal and occipito-temporal cortices with increased entropy (p < 0.05) in the clustering structure (i.e., more segregation in the controls). Moreover, we noticed a statistically reduced modularity (p < 0.001) in the autistic patients compared with the controls. Significantly reduced eigenvector centrality values (p < 0.05) in the patients were observed in the same regions that were identified in the FSC analysis. Limitations: There is considerable heterogeneity in the fMRI acquisition protocols among the sites that contributed to the ABIDE data set (e.g., scanner type, pulse sequence, duration of scan and resting-state protocol). Moreover, the sites differed in many variables related to sample characterization (e.g., age, IQ and ASD diagnostic criteria). Therefore, we cannot rule out the possibility that additional differences in functional network organization would be found in a more homogeneous data sample of individuals with ASD. Conclusion: Our results suggest that the organization of the whole-brain functional network in patients with ASD is different from that observed in controls, which implies a reduced modularity of the brain functional networks involved in sensorimotor, social, affective and cognitive processing.Artigo Científico SNA-Based Reasoning for Multi-Agent Team Composition(2015) ANDRE FILIPE DE MORAES BATISTA; Marietto, Maria das Graças BrunoThe social network analysis (SNA), branch of complex systems can be used in the construction of multi agent systems. This paper proposes a study of how social network analysis can assist in modeling multi agent systems, while addressing similarities and differences between the two theories. We built a prototype of multi-agent systems for resolution of tasks through the formation of teams of agents that are formed on the basis of the social network established between agents. Agents make use of performance indicators to assess when should change their social network to maximize the participation in teams.Artigo Científico Uma introdução ao tema Recuperação de Informações Textuais(2013) FABRÍCIO JAILSON BARTHO tema Recuperação de Informação sempre foi um tema muito explorado na academia e no mercado. A forma com que os eventos acadêmicos são conduzidos demonstra uma maturidade muito grande da área, inclusive com uma ligação muito forte com o mercado. Inúmeros livros sobre este tema já foram publicados. No entanto, são poucos os livros publicados em português. Este tutorial tenta preencher esta lacuna apresentando uma introdução sobre o tema Recuperação de Informação, abordando: as principais definições e conceitos da área; os principais modelos que regem o desenvolvimento dos Sistemas de Recuperação de Informação, e; os métodos usualmente empregados na avaliação de Sistemas de Recuperação de Informação.Artigo Científico Pollution, bad-mouthing, and local marketing: The underground of location-based social networks(2014) Costa, Helen; Merschmann, Luiz H.C.; FABRÍCIO JAILSON BARTH; Benevenuto, FabrícioLocation Based Social Networks (LBSNs) are new Web 2.0 systems that are attracting new users in exponential rates. LBSNs like Foursquare and Yelp allow users to share their geographic location with friends through smartphones equipped with GPS, search for interesting places as well as posting tips about existing locations. By allowing users to comment on locations, LBSNs increasingly have to deal with new forms of spammers, which aim at advertising unsolicited messages on tips about locations. Spammers may jeopardize the trust of users on the system, thus, compromising its success in promoting location-based social interactions. In spite of that, the available literature is very limited in providing a deep understanding of this problem. In this paper, we investigated the task of identifying different types of tip spam on a popular Brazilian LBSN system, namely Apontador. Based on a labeled collection of tips provided by Apontador as well as crawled information about users and locations, we identified three types of irregular tips, namely local marketing, pollution and, bad-mouthing. We leveraged our characterization study towards a classification approach able to differentiate these tips with high accuracy.Artigo Científico Detection of the Optic Nerve Head in Fundus Images of the Retina with Gabor Filters and Phase Portrait Analysis(2010) Rangayyan, Rangaraj M.; Zhu, Xiaolu; FABIO JOSE AYRES; Ells, Anna L.We propose a method using Gabor filters and phase portraits to automatically locate the optic nerve head (ONH) in fundus images of the retina. Because the center of the ONH is at or near the focal point of convergence of the retinal vessels, the method includes detection of the vessels using Gabor filters, detection of peaks in the node map obtained via phase portrait analysis, and an intensity-based condition. The method was tested on 40 images from the Digital Retinal Images for Vessel Extraction (DRIVE) database and 81 images from the Structured Analysis of the Retina (STARE) database. An ophthalmologist independently marked the center of the ONH for evaluation of the results. The evaluation of the results includes free-response receiver operating characteristics (FROC) and a measure of distance between the manually marked and detected centers. With the DRIVE database, the centers of the ONH were detected with an average distance of 0.36 mm (18 pixels) to the corresponding centers marked by the ophthalmologist. FROC analysis indicated a sensitivity of 100% at 2.7 false positives per image. With the STARE database, FROC analysis indicated a sensitivity of 88.9% at 4.6 false positives per image.Artigo Científico Effect of Pixel Resolution on Texture Features of Breast Masses in Mammograms(2010) Rangayyan, Rangaraj M.; Nguyen, Thanh M.; FABIO JOSE AYRES; Nandi, Asoke K.The effect of pixel resolution on texture features computed using the gray-level co-occurrence matrix (GLCM) was analyzed in the task of discriminating mammographic breast lesions as benign masses or malignant tumors. Regions in mammograms related to 111 breast masses, including 65 benign masses and 46 malignant tumors, were analyzed at pixel sizes of 50, 100, 200, 400, 600, 800, and 1,000 μm. Classification experiments using each texture feature individually provided accuracy, in terms of the area under the receiver operating characteristics curve (AUC), of up to 0.72. Using the Bayesian classifier and the leave-one-out method, the AUC obtained was in the range 0.73 to 0.75 for the pixel resolutions of 200 to 800 μm, with 14 GLCM-based texture features using adaptive ribbons of pixels around the boundaries of the masses. Texture features computed using the ribbons resulted in higher classification accuracy than the same features computed using the corresponding regions within the mass boundaries. The t test was applied to AUC values obtained using 100 repetitions of random splitting of the texture features from the ribbons of masses into the training and testing sets. The texture features computed with the pixel size of 200 μm provided the highest average AUC with statistically highly significant differences as compared to all of the other pixel sizes tested, except 100 μm.- Entre ideias e instituições: considerações sobre Mangabeira Unger e a "situação constitucional" do Brasil(2011) DIEGO WERNECK ARGUELHESA proposta maior de Roberto Mangabeira Unger no campo do direito consiste em reorientar o pensamento jurídico rumo ao que chama de imaginação institucional: um processo de identificação e exploração de futuros institucionais alternativos implícitos nas ambiguidades e contradições de nossas instituições e aspirações coletivas. No texto “A constituição do experimentalismo democrático”, apresenta razões para justificar a necessidade de reorientarmos, sob a forma de imaginação institucional, o pensamento sobre o direito constitucional no Brasil e sugere aplicações desse tipo de raciocínio a alguns aspectos centrais de nossa “situação constitucional”. Neste comentário ao texto de Unger, procuro (a) inserir essa dúplice abordagem da situação constitucional do Brasil — defesa de um método de pensamento e aplicação desse método a alguns temas e estruturas do direito constitucional brasileiro — na perspectiva mais ampla do pensamento ungeriano sobre o direito; (b) levantar, a partir de critérios extraídos do método que Unger propõe, algumas perplexidades quanto às propostas de reforma via imaginação institucional esboçadas no texto. Mais especificamente, discuto algumas dificuldades em se compatibilizar, com o próprio procedimento de análise proposto por Unger, sua proposta de se resolver impasses entre o presidente e o Congresso com a convocação de eleições antecipadas para ambos os poderes. A meta é contribuir para explicitar algumas características centrais do método de pensamento ungeriano e ilustrar sua operação, ao mesmo tempo que aponto possíveis dificuldades em sua aplicação em casos específicos de redesenho institucional.
Artigo Científico The Hidden Pitfalls of Inclusive Innovation(2015) Narsalay, Raghav; Pongeluppe, Leandro S.; Light, DavidArtigo Científico Observability analysis of inertial navigation errors from optical flow subspace constraint(2016) Waldmann, Jacques; Silva, Raul Ikeda Gomes da; Chagas, Ronan Arraes Jardim