Browsing by Author "Pestana, Pedro"
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- Economic impact of healthcare cyber risksPublication . Brilhante, M. Fátima; Mendonça, Sandra; Pestana, Pedro; Rocha, M. Luísa; Santos, RuiPurpose: The healthcare sector is a primary target for cybercriminals, with health data breaches ranking among the most critical threats. Despite stringent penalties imposed by the U.S. Department of Health and Human Services Office for Civil Rights (OCR), vulnerabilities still persist due to slow detection and ineffective data protection measures. On the other hand, as organizations are often reluctant to disclose security breaches for fear of reputational and market share losses, penalties can serve as a useful proxy for quantifying losses and insurance claims. Methods: This study analyzes fines and settlements (2008–2024) using the traditional lognormal, general extreme value (GEV) and other heavy-tailed statistical models, including the geo-max-stable loglogistic law, and also the mixture models hyperexponential and hyperloglogistic. Results: Mixture models, either the hyperexponential or the hyperloglogistic, deliver the best fit for OCR penalties, and for yearly maxima, the best fit is achieved with the GEV distribution. Regarding Attorneys General fines, the hyperexponential model is optimal, with the GEV model excelling again for their yearly maxima. Hence, mixture models effectively capture the dual nature of penalty data, comprising clusters of moderate and extreme values. However, yearly maxima align better with the GEV model. Conclusions: The findings suggest that while Panjer’s theory for aggregate claims suffices for moderate claims, it must be supplemented with strategies to address extreme cybercrime scenarios, ensuring insurers and reinsurers can manage severe losses effectively.
- European Portuguese Emotional Discourse DatabasePublication . Ferro, Rafael; Pestana, PedroThe European Portuguese Emotional Discourse Database (EPEDD) is an acted Portuguese speech emotional database. It was developed at Escola das Artes da Universidade Católica do Porto, in the scope of a master’s project during the academic year of 2016-2017, by Rafael Ferro and his dissertation director Pedro Pestana. The database consists in 8 actors with an equal representation of each gender, 5 long sentences, 5 short sentences and two single words and 9 emotions: anger, apathy, disgust, fear, interest, joy, sadness and surprise and neutral. In the Actors folder, you will find the recorded emotional utterances, organised by actors and emotions. Additionally, you will find a text file with information concerning the actors.
- Generalized beta models and population growth: so many routes to chaosPublication . Brilhante, M. Fátima; Gomes, M. Ivette; Mendonça, Sandra; Pestana, Dinis; Pestana, PedroLogistic and Gompertz growth equations are the usual choice to model sustainable growth and immoderate growth causing depletion of resources, respectively. Observing that the logistic distribution is geo-max-stable and the Gompertz function is proportional to the Gumbel max-stable distribution, we investigate other models proportional to either geo-max-stable distributions (log-logistic and backward log-logistic) or to other max-stable distributions (Fréchet or max-Weibull). We show that the former arise when in the hyper-logistic Blumberg equation, connected to the Beta (Formula presented.) function, we use fractional exponents (Formula presented.) and (Formula presented.), and the latter when in the hyper-Gompertz-Turner equation, the exponents of the logarithmic factor are real and eventually fractional. The use of a BetaBoop function establishes interesting connections to Probability Theory, Riemann–Liouville’s fractional integrals, higher-order monotonicity and convexity and generalized unimodality, and the logistic map paradigm inspires the investigation of the dynamics of the hyper-logistic and hyper-Gompertz maps.
- Lindenmeyer systems and the harmony of fractalsPublication . Pestana, PedroAn interactive musical application is developed for realtime improvisation with a machine based on Lindenmeyer-systems. This has been used on an installation whose goal is to draw the attention of unexperienced users to the wealth of realtime applications in computer music. Issues on human computer interaction and improvisation grammars had to be dealt with, as well as probabilistic strategies for musical variation. The choice of L-systems as a basis for machine composition is a consequence of their ability to create results that easily have aesthetic appeal, both in the realms of sound and image.
- Measuring the risk of vulnerabilities exploitationPublication . Brilhante, Maria de Fátima; Pestana, Dinis; Pestana, Pedro; Rocha, Maria LuísaModeling the vulnerabilities lifecycle and exploitation frequency are at the core of security of networks evaluation. Pareto, Weibull, and log-normal models have been widely used to model the exploit and patch availability dates, the time to compromise a system, the time between compromises, and the exploitation volumes. Random samples (systematic and simple random sampling) of the time from publication to update of cybervulnerabilities disclosed in 2021 and in 2022 are analyzed to evaluate the goodness-of-fit of the traditional Pareto and log-normal laws. As censoring and thinning almost surely occur, other heavy-tailed distributions in the domain of attraction of extreme value or geo-extreme value laws are investigated as suitable alternatives. Goodness-of-fit tests, the Akaike information criterion (AIC), and the Vuong test, support the statistical choice of log-logistic, a geo-max stable law in the domain of attraction of the Fréchet model of maxima, with hyperexponential and general extreme value fittings as runners-up. Evidence that the data come from a mixture of differently stretched populations affects vulnerabilities scoring systems, specifically the common vulnerabilities scoring system (CVSS).
- Sir Pinski rides againPublication . Gomes, Maria Ivette; Pestana, Dinis; Pestana, PedroThe iterative procedure of removing “almost everything” from a triangle ultimately leading to the Sierpinski's gasket S is well-known. But what is in fact left when almost everything has been taken out? Using the Sir Pinski's game described by Schroeder [4], we identify two dual sets of invariant points in this exquisite game, and from these we identify points left over in Sierpinski gasket. Our discussion also shows that the chaos game does not generate the Sierpinski gasket. It generates an approximation or, at most, a subset of S.
- A systematic review of teacher-facing dashboards for collaborative learning activities and tools in online higher educationPublication . Romão, Tiago; Pestana, Pedro; Morgado, LeonelDashboard for online higher education support monitoring and evaluation of students’ interactions, but mostly limited to interaction occurring within learning management systems. In this study, we sought to find which collaborative learning activities and tools in online higher education are included in teaching dashboards. By following Kitchenham’s procedure for systematic reviews, 36 papers were identified according to this focus and analysed. The results identify dashboards supporting collaborative tools, both synchronous and asynchronous, along categories such as learning management systems, communication tools, social media, computer programming code management platforms, project management platforms, and collaborative writing tools. Dashboard support was also found for collaborative activities, grouped under four categories of forum discussion activities, three categories of communication activities and four categories of collaborative editing/sharing activities, though most of the analysed dashboards only provide support for no more than two or three collaborative tools. This represents a need for further research on how to develop dashboards that combine data from a more diverse set of collaborative activities and tools.