ALCARÁS, J. R. Acoustic wave scattering and internal fields analysis of viscoelastic materials. 2018. 43 f. Dissertation (M.Sc.-Postgraduate program in Physics Applied to Medicine and Biology)

This study presents an algorithmic strategy to analyze a small set of social network information to monitor the dengue disease. Previous studies have achieved similar results based on large datasets of Twitter microblogs. In this study, we successfully map dengue cases using a small data collection of tweets from a medium-size city. A set of modules were constructed to collect, categorize, and display dengue-related tweets. We compared the collected tweets with real data from confirmed dengue cases. We showed a significant correlation between the number of confirmed dengue cases and the number of dengue-related tweets, even considering such a small dataset. The results of this approach may be relevant in public health policies.

In this work, Polyaniline (PANI) was used as a sensing film for pH measures due to its characteristic of switching protonation states under acid and alkaline solutions. Equally produced films had their sensitivity (electric response versus pH) measured before and after being under the influence of a constant electric potential (from 3.5 to 6 V, one for each film) for the analysis on how the electric potential influenced the sensitivity. Then, the protonation caused by the application of the first potential was reversed by applying a constant 5 V reverse potential and the sensitivity was then evaluated again. The results show, on average, a constant relation between intensity of protonation and the potential applied and that the process of protonation is reversible by applying a higher opposite potential then the protonation one.

Discarded plastic is subjected to weather effects from different ecosystems and becomes microplastic particles. Due to their small size, they have spread across the planet. Their presence in living organisms can have several harmful consequences, such as altering the interaction between prey and predator. Huang et al. successfully modeled this system presenting numerical results of ecological relevance. Here, we have rewritten their equations and solved a set of them analytically, confirming that microplastic particles accumulate faster in predators than in prey and calculating the time values from which it happens. Using these analytical solutions, we have retrieved the Lotka–Volterra predator–prey model with time-varying intraspecific coefficients, allowing us to interpret ecological quantities referring to microplastics dispersion. After validating our equations, we solved analytically particular situations of ecological interest, characterized by extreme effects on predatory performance, and proposed a second-order differential equation as a possible next step to address this model. Our results open space for further refinement in the study of predator–prey models under the effects of microplastic particles, either exploring the second-order equation that we propose or modify the Huang et al. model to reduce the number of parameters, embedding in the time-varying intraspecies coefficients all the adverse effects caused by microplastic particles.