Publications

• Estimative of real number of infections by COVID-19 on Brazil and possible scenarios. Infectious Disease Modelling, v. 5, p. 720-736. 2020. doi/10.1016/j.idm.2020.09.004

Authors: P. H. P. Cintra & F. N. Fontinele

Abstract: This paper attempts to provide methods to estimate the real scenario of the novel coronavirus pandemic in Brazil, specifically in the states of Sao Paulo, Pernambuco, Espirito Santo, Amazonas and the Federal District. By the use of a SEIRD mathematical model with age division, we predict the infection and death curves, stating the peak date for Brazil and above states. We also carry out a prediction for the ICU demand in these states and for how severe possible collapse in the local health system would be. Finally, we establish some future scenarios including the relaxation on social isolation and the introduction of vaccines and other efficient therapeutic treatments against the virus.

• Uncanny valley hypothesis and hierarchy of facial features in the human likeness continua: An eye-tracking approach. Psychology & Neuroscience, 2022. https://psycnet.apa.org/doi/10.1037/pne0000281

Authors: I. B. F. Grebot, P. H. P. Cintra, E. F. F. de Lima, M. V. M. de Castro, & M. Jr., Rui

Abstract: Objective: The uncanny valley hypothesis refers to a subjective experience of eeriness to highly human-like objects (e.g., realistic avatars). There is evidence that objects at the human–avatar category boundary along the dimension of human likeness (DHL) are more likely to evoke the uncanny valley effect. Literature has focused on the affective domain of the phenomenon and studies on the cognitive demands are few. Here, we investigate whether perceptual ambiguity could affect the hierarchical processing of facial features. Our study investigated categorical perception of female and male faces along the DHL. Method: Participants performed a real vs. artificial categorization task and behavioral measures (categorization threshold and response time; RT) were calculated to determine avatar, boundary, and human face conditions. Results: An analysis on the hierarchy of gaze dwell time in regions of interest (ROI; eyes, nose, and mouth) showed greater dwell time for the nose area of boundary faces compared to the nose area of avatar and human faces. Conclusions: Results showed that perceptual discrimination difficulty changed the allocation of attentional resources in boundary faces. Such output may contribute on how we process artificial faces and might improve users’ experiences from highly realistic characters.

• Sequential time-window learning with approximate Bayesian computation: an application to epidemic forecasting. Nonlinear Dynamics, 2022. https://doi.org/10.1007/s11071-022-07865-x

Authors: J. P. Valeriano, P. H. P. Cintra, G. Libotte, I. Reis, F. N. Fontinele, R. Silva & S. Malta

Abstract: The long duration of the COVID-19 pandemic allowed for multiple bursts in the infection and death rates, the so-called epidemic waves. This complex behavior is no longer tractable by simple compartmental model and requires more sophisticated mathematical techniques for analyzing epidemic data and generating reliable forecasts. In this work, we propose a framework for analyzing complex dynamical systems by dividing the data in consecutive time-windows to be separately analyzed. We fit parameters for each timewindow through an approximate Bayesian computation (ABC) algorithm, and the posterior distribution of parameters obtained for one window is used as the prior distribution for the next window. This Bayesian learning approach is tested with data on COVID-19 cases in multiple countries and is shown to improve ABC performance and to produce good short-term forecasting.

Analysis of informative priors' effects on epidemic curve fitting. Encontro Acadêmico de Modelagem Computacional. National Laboratory for Scientific Computing, Petrópolis, RJ, Brazil. 2021.

Authors: J. P. Valeriano, P. H. P. Cintra, F. N. Fontinele, I. Reis, L. Lima & T. L. S. Alves

Abstract: In order to verify the effects of using empirical priors to fit epidemiological models through the ABC- SMC method, we considered the SEIRD model with different prior distributions combinations, admitting experimental measurements or not. Comparing the results of these combinations, we observe that the fit with the minimal RMSD final value was the one using all available empirical distributions as priors. However, the values of the parameters obtained do not belong, in general, to the 95% CI of the empirical distributions. We further discuss possible reasons for this deviation.

• Mathematical Models for Describing and Predicting the COVID-19 Pandemic Crisis. (2020). arXiv preprint arXiv:2006.02507. 2020.

Authors: P. H. P. Cintra, M. F. Citeli & F. N. Fontinele

Abstract: The present article studies the extension of two deterministic models for describing the novel coronavirus pandemic crisis, the SIR model and the SEIR model. The models were studied and compared to real data in order to support the validity of each description and extract important information regarding the pandemic, such as the basic reproductive number R0, which might provide useful information concerning the rate of increase of the pandemic predicted by each model. We next proceed to making predictions and comparing more complex models derived from the SEIR model with the SIRD model, in order to find the most suitable one for describing and predicting the pandemic crisis. Aiming to answer the question if the simple SIRD model is able to make reliable predictions and deliver suitable information compared to more complex models.

• Estimating the Number of Infected by COVID-19 in Italy. (2020). https://doi.org/10.20944/preprints202005.0361.v1

Authors: P. H. P. Cintra & F. N. Fontinele

Abstract: Italy suffered heavily with the new pandemic crisis caused by the novel coronavirus SARS-CoV-2. Given the low number of tests performed on the early stages of the outbreak, Italy lost track of most of infections. We use a modified SEIR model to reconstruct the most realistic infection curve using the hospitalization curve of the registered data. Using this method we estimated that, by the end of the first infection wave, about 3-4% of the population will have been infected by the virus. Following the same process, the number of deaths is projected to be between 100000 to 115000. We also find a significant correlation between the number of tests performed, the fraction of undocumented infections and the rate of change dI/dt of the real infection curve. We conclude that herd immunity is not enough to contain further spread of the disease inside the country.

• Forecasting COVID-19 Pandemic in Mozambique and Estimating Possible Scenarios. (2020).. arXiv preprint arXiv:2007.13933.

Authors: C. M. Paulo, F. N. Fontinele & P. H. P. Cintra

Abstract: COVID-19 is now the largest pandemic crisis of this century, with over 16 million registered cases worldwide. African countries have now begun registering an increasing number of cases, yet, not many models developed focus in specific African countries. In our study we use a simple SEIR model to evaluate and predict future scenarios regarding the pandemic crisis in Mozambique. We compare the effect of different policies on the infection curve and estimate epidemiological parameters such as the current infection reproduction number Rt and the growth rate g. We have found a low value for Rt, ranging from 1.11 to 1.48 and a positive growth rate, between g = 0.22 to 0.27. Our simulations also suggest that a lockdown shows potential for reducing the infection peak height in 28%, on average, ranging from 20 to 36%.

• Ligação diatômica: Uma abordagem clássica e quântica. (2019). Physicae Organum - Revista dos Estudantes de Física da UnB, 5(2), 42-62. https://periodicos.unb.br/index.php/physicae/article/view/24022

Authors: P. H. P. Cintra

Abstract: O presente artigo tem a intenção de evidenciar as diferenças entre a análise clássica e quântica de uma molécula diatômica, nos aspectos das transições vibracionais, mostrando os resultados e predições de cada método, descrevendo as soluções e comparando elas com o comportamento real. Deixando claro as limitações e validades de cada método.