Coleção de Artigos Acadêmicos
URI permanente para esta coleçãohttps://repositorio.insper.edu.br/handle/11224/3227
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123 resultados
Resultados da Pesquisa
Artigo Científico Direitos Humanos, inteligência artificial e privacidade(2019) Cassino, João Francisco; RODOLFO DA SILVA AVELINO; Silveira, Sérgio Amadeu daEste texto trata dos riscos e implicações da inteligência artificial e dos algoritmos para os objetivos contidos na Declaração Universal dos Direitos Humanos. Nesse sentido, as perspectivas de James Der Derian, Frank Pasquale, David Chandler, Shoshana Zuboff, Philip N. Howard e Nick Srnicek foram mobilizadas para a compreensão da atual fase do capitalismo global, do mercado de captura e o processamento em massa de dados pessoais. Diversos casos descritos indicam que a privacidade é cada vez menos respeitada enquanto as empresas protegem seus segredos competitivos com patentes, códigos fechados e acordos de confidencialidade. Técnicas de Big Data e algoritmos em rede podem ser utilizados para melhorar e agilizar a administração pública, mas também resultam em novas práticas discriminatórias que violam o direito à privacidade, à liberdade de expressão e à justiça. Grupos étnicos e raciais, mulheres e comunidade LGBT já sofrem com decisões tomadas por sistemas computacionais autômatos que levam à segregação e ao preconceito.Artigo Científico An investigation of the distribution of gaze estimation errors in head mounted gaze trackers using polynomial functions(2018) Mardanbegi, Diako; ANDREW TOSHIAKI NAKAYAMA KURAUCHI; Morimoto, Carlos H.Second order polynomials are commonly used for estimating the point-of-gaze in head-mounted eye trackers. Studies in remote (desktop) eye trackers show that although some non-standard 3rd order polynomial models could provide better accuracy, high-order polynomials do not necessarily provide better results. Different than remote setups though, where gaze is estimated over a relatively narrow field-of-view surface (e.g. less than 30x20 degrees on typical computer displays), head-mounted gaze trackers (HMGT) are often desired to cover a relatively wider field-of-view to make sure that the gaze is detected in the scene image even for extreme eye angles. In this paper we investigate the behavior of the gaze estimation error distribution throughout the image of the scene camera when using polynomial functions. Using simulated scenarios, we describe effects of four different sources of error: interpolation, extrapolation, parallax, and radial distortion. We show that the use of third order polynomials result in more accurate gaze estimates in HMGT, and that the use of wide angle lenses might be beneficial in terms of error reduction.Artigo Científico Identification of alterations associated with age in the clustering structure of functional brain networks(2018) Guzman, Grover E. C.; Sato, Joao R.; MACIEL CALEBE VIDAL; Fujita, AndreInitial studies using resting-state functional magnetic resonance imaging on the trajectories of the brain network from childhood to adulthood found evidence of functional integration and segregation over time. The comprehension of how healthy individuals’ functional integration and segregation occur is crucial to enhance our understanding of possible deviations that may lead to brain disorders. Recent approaches have focused on the framework wherein the functional brain network is organized into spatially distributed modules that have been associated with specific cognitive functions. Here, we tested the hypothesis that the clustering structure of brain networks evolves during development. To address this hypothesis, we defined a measure of how well a brain region is clustered (network fitness index), and developed a method to evaluate its association with age. Then, we applied this method to a functional magnetic resonance imaging data set composed of 397 males under 31 years of age collected as part of the Autism Brain Imaging Data Exchange Consortium. As results, we identified two brain regions for which the clustering change over time, namely, the left middle temporal gyrus and the left putamen. Since the network fitness index is associated with both integration and segregation, our finding suggests that the identified brain region plays a role in the development of brain systems.Artigo Científico Particle learning for Bayesian semi-parametric stochasticvolatility model(2019) Virbickaitė, Audronė; HEDIBERT FREITAS LOPES; Ausín, M. Concepción; Galeano, PedroThis article designs a Sequential Monte Carlo (SMC) algorithm for estimation of Bayesian semi-parametric Stochastic Volatility model for financial data. In particular, it makes use of one of the most recent particle filters called Particle Learning (PL). SMC methods are especially well suited for state-space models and can be seen as a cost-efficient alternative to Markov Chain Monte Carlo (MCMC), since they allow for online type inference. The posterior distributions are updated as new data is observed, which is exceedingly costly using MCMC. Also, PL allows for consistent online model comparison using sequential predictive log Bayes factors. A simulated data is used in order to compare the posterior outputs for the PL and MCMC schemes, which are shown to be almost identical. Finally, a short real data application is included.Artigo Científico On the Long-Run Volatility of Stocks(2018) Carvalho, Carlos M.; HEDIBERT FREITAS LOPES; McCulloch, Robert E.In this article, we investigate whether or not the volatility per period of stocks is lower over longer horizons.Taking the perspective of an investor, we evaluate the predictive variance of k-period returns under differentmodel and prior specifications. We adopt the state-space framework of Pástor and Stambaugh to model thedynamics of expected returns and evaluate the effects of prior elicitation in the resulting volatility estimates.Part of the developments includes an extension that incorporates time-varying volatilities and covariancesin a constrained prior information set-up. Our conclusion for the U.S. market, under plausible prior specifi-cations, is that stocks are less volatile in the long run. Model assessment exercises demonstrate the modelsand priors supporting our main conclusions are in accordance with the data. To assess the generality of theresults, we extend our analysis to a number of international equity indices. Supplementary materials for thisarticle are available online.Artigo Científico Walk on the Wild Side: Temporarily Unstable Paths and Multiplicative Sunspots(2019) Ascari, Guido; Bonomolo, Paolo; HEDIBERT FREITAS LOPESWe propose a generalization of the rational expectations framework to allow for temporarily unstable paths. Our approach introduces multiplicative sunspot shocks and it yields drifting parameters and stochastic volatility. Then, we provide an econometric strategy to estimate this generalized model on the data. The methodology allows the data to choose between different possible alternatives: determinacy, indeterminacy, and temporary instability. We apply our methodology to US inflation dynamics in the 1970s through the lens of a simple New Keynesian model. When temporarily unstable paths are allowed, the data unambiguously select them to explain the stagflation period in the 1970s.- Sham Litigation e Garantias Fundamentais do Processo: Três Breves Perguntas (Ou Reflexões)(2019) Osna, Gustavo; Renzetti, Bruno Polonio
- Mumbuca é dinheiro(2019) Cernev, Adrian KemmerO caso aborda a evolução da moeda social Mumbuca, implantada de forma pioneira no município de Maricá-RJ, a qual foi a primeira moeda social digital do país. Ao longo dos seus seis primeiros anos de existência, a moeda vivenciou importantes inovações tecnológicas e de modelo de negócio, assim como o crescimento expressivo da base de usuários. A tecnologia inicial de cartões magnéticos foi substituída pelo aplicativo e plataforma E-Dinheiro, em um modelo híbrido de dinheiro e pagamentos móveis (mobile money e mobile payments). Serviços foram criados para diferentes públicos da plataforma digital e a moeda social parecia alcançar os objetivos sociais propostos. Entretanto, surgiram novos desafios tecnológicos, de negócio e de governança, os quais requeriam uma postura inovadora de seus gestores. Este trabalho sucede o caso de ensino “Mumbuca: a primeira moeda social digital do Brasil”, publicado na GVcasos vol. 6, n.2, jul-dez 2016, podendo ser utilizado como sua continuação.
Artigo Científico Immigration and the path dependence of education: the case of German-speakers in São Paulo, Brazil (1840–1920)(2018) Souza, Bruno Gabriel Witzel deThis article studies the path dependence of human capital accumulation in the state of São Paulo, Brazil. It focuses on the impacts of German-speaking immigrants on education through three channels: their share of the population in the nineteenth century, their on-the-job skills, and the schools they founded. Using a new dataset based on almanacs from 1873 and 1888, these effects are evaluated for the nineteenth, early twentieth, and early twenty-first centuries. The article shows that the institutionalized demand for education of these immigrants, reflected by the establishment of schools, was their main contribution to the accumulation of human capital. The effect of German schools on educational levels required a period to mature and dissipated over time. Nevertheless, its influence was substantial at the beginning of the twentieth century, affecting enrolment levels in private and state schools, a result that suggests the existence of spillover and contagion effects. Moreover, current indicators for stocks and flows of human capital in São Paulo are strongly associated with their historical levels. At the same time, this path dependence is conditional on the type of school: while a positive persistence is found for the private system throughout the twentieth century, convergence occurred in state schools.Artigo Científico Actual and counterfactual growth incidence and deltaLorenz curves: Estimation and inference(2019) Ferreira, Francisco H. G.; SERGIO PINHEIRO FIRPO; Galvao, Antonio F.