Publications 2019

Book Chapters

33.  Periodic INAR(1) Models with Skellam-Distributed Innovations

Santos, Cláudia and Pereira, Isabel and Scotto, Manuel

Computational Science and Its Applications – ICCSA 2019. ICCSA 2019. Lecture Notes in Computer Science


In this paper, an integer-valued autoregressive model of order one (INAR(1)) with time-varying parameters and driven by a periodic sequence of innovations is introduced. The proposed INAR(1) model is based on the signed thinning operator defined by Kachour and Truquet (2011) and conveniently adapted to the periodic case. Basic notations and definitions concerning the periodic signed thinning operator are provided. Based on this thinning operator, Chesneau and Kachour (2012) established a signed INAR(1) model. Motivated by the work of Chesneau and Kachour (2012), we introduce a periodic model, denoted by S-PINAR(1), with period s. In contrast to conventional INAR(1) models, these models are defined in Z allowing for negative values both for the series and its autocorrelation function. For a proper Z-valued time series, a distribution for the innovation term defined on Z is required. The S-PINAR(1) model assumes a specific innovation distribution, the Skellam distribution. Regarding parameter estimation, two methods are considered: conditional least squares and conditional maximum likelihood. The performance of the S-PINAR(1) model is assessed through a simulation study. | doi | Peer Reviewed

32.  Modelling overdispersion with integer-valued moving average processes

Silva, Maria Eduarda and Silva, Isabel and Torres, Cristina

Stochastic Models, Statistics and Their Applications

Springer International Publishing

A new first-order integer-valued moving average, INMA(1), model based on the negative binomial thinning operation defined by Risti´c et al. [21] is proposed and characterized. It is shown that this model has negative binomial (NB) marginal distribution when the innovations follow a NB distribution and therefore it can be used in situations where the data present overdispersion. Additionally, this model is extended to the bivariate context. The Generalized Method of Moments (GMM) is used to estimate the unknown parameters of the proposed models and the results of a simulation study that intends to investigate the performance of the method show that, in general, the estimates are consistent and symmetric. Finally, the proposed model is fitted to a real dataset and the quality of the adjustment is evaluated. | doi | Peer Reviewed

31.  Normalized entropy aggregation for inhomogeneous large-scale data

Costa, Maria da Conceição and Macedo, Pedro

Theory and Applications of Time Series Analysis. ITISE 2018. Contributions to Statistic


It was already in the fifties of the last century that the relationship between information theory, statistics, and maximum entropy was established, following the works of Kullback, Leibler, Lindley and Jaynes. However, the applications were restricted to very specific domains and it was not until recently that the convergence between information processing, data analysis and inference demanded the foundation of a new scientific area, commonly referred to as Info-Metrics. As huge amount of information and large-scale data have become available, the term "big data" has been used to refer to the many kinds of challenges presented in its analysis: many observations, many variables (or both), limited computational resources, different time regimes or multiple sources. In this work, we consider one particular aspect of big data analysis which is the presence of inhomogeneities, compromising the use of the classical framework in regression modelling. A new approach is proposed, based on the introduction of the concepts of info-metrics to the analysis of inhomogeneous large-scale data. The framework of information-theoretic estimation methods is presented, along with some information measures. In particular, the normalized entropy is tested in aggregation procedures and some simulation results are presented. | doi | Peer Reviewed

30.  The HJ-biplot visualization of the Singular Spectrum Analysis method

Silva, Alberto Oliveira da and Freitas, Adelaide

ITISE 2019: International Conference on Time Series and Forecasting: Proceedings of Papers

Godel Impresiones Digitales S.L.

Time series data usually emerge in many scientific domains. The extraction of essential characteristics of this type of data is crucial to characterize the time series and produce, for example, forecasts. In this work, we take advantage of the trajectory matrix constructed in the Singular Spectrum Analysis, as well as of its decomposition through the Principal Component Analysis via Partial Least Squares, to implement a graphical display employing the Biplot method. In these graphs, one can visualize and identify patterns in time series from the simultaneous representation of both rows and columns of such decomposed matrices. The interpretation of various features of the proposed biplot is discussed from a real-world data set. | Peer Reviewed


29.  Cardiorespiratory physiotherapy as a career choice-perspective of students and physiotherapists in Portugal

Marques, Alda and Oliveira, Ana and Machado, Ana and Jácome, Cristina and Cruz, Joana and Pinho, Tânia and Hall, Andreia and Alvelos, Helena and Brooks, Dina

Physiotherapy theory and practice

Taylor & Francis

We investigated Portuguese physiotherapy students' and physiotherapists' (1) perceptions of cardiorespiratory physiotherapy (CRP); (2) factors that influenced their decision to pursue a career in CRP; and (3) suggestions to develop CRP. Online surveys were disseminated to final year students and physiotherapists. A number of 189 students (mean age 23 [SD 6] years; 78% ♀) and 375 physiotherapists (mean age 31 [SD 8] years; 78% ♀) participated. Students' opinions about CRP were positively influenced by lecturers (n = 112, 69%), clinical experiences (n = 110, 68%), and scientific evidence (n = 93, 57%). Only 13% of students were "extremely interested" in specializing in CRP. Interest in the area and clinical exposure were the main factors influencing students to pursue a career in CRP. A percentage of 15 of responding physiotherapists were working in CRP. Their decision to pursue a CRP career was most influenced by their interest in the area (n = 37, 67%) and opportunity to work in acute settings (n = 31; 56%). Main suggestions to develop CRP were (1) include placements in CRP; (2) emphasize health promotion within the curriculum; and (3) develop CRP skills in broader contexts and training. Strategies focusing on changing the curriculum, increasing exposure to CRP, providing good mentorship, developing health promotion activities, and creating postgraduate courses may increase the attractiveness for CRP. | doi | Peer Reviewed

28.  Exploring symmetry in rosettes of Truchet tiles

Hall, Andreia and Almeida, Paulo J. and Teixeira, Ricardo

Journal of Mathematics and the Arts

Taylor & Francis

In 1704 the French priest S ebastien Truchet published a paper where he explored and counted patterns made up from a square divided by a diagonal line into two colored parts,, now known as a Truchet tile. A few years later, Father Dominique Douat continued Truchet's work and published a book in 1722 containing many more patterns and further counts of con gurations. In this paper, we extend the work introduced by Truchet and Douat by considering all possible rosettes made up of an mXn array of square or non-square Truchet tiles. We then classify the rosettes according to their symmetry group and count all the distinct rosettes in each group, for all possible sizes. The results are summarized in a separate section where we further analyze the asymptotic behavior of the counts for square arrays. Finally, some applications are shown using two types of square flexagons. | doi | Peer Reviewed

27.  Famílias e mobilidade interna: uma análise com base nos dados do recenseamento de 2011

Gomes, Maria Cristina Sousa and Freitas, Adelaide and Pinto, Maria Luís Rocha

Análise Social

Universidade de Lisboa, Instituto de Ciências Sociais

Não é frequente considerar-se no âmbito das migrações internas a mobilidade familiar. No entanto, os dados mostram que há características dos municípios que determinam como as famílias se movimentam e se distribuem. A análise de associações entre características populacionais e familiares e variações de fluxos migratórios dos 308 municípios, desenvolvida com base na informação do recenseamento de 2011, pretende refletir sobre a mobilidade familiar em Portugal, salientando aspetos diferenciadores. As associações encontradas, sob duas escalas territoriais, permitem ressaltar dinâmicas territoriais distintas no que respeita aos fenómenos de atração e repulsão associadas à deslocação ou permanência da população nos territórios. | doi | Peer Reviewed

26.  Investigating the use and acceptance of technologies by professors in a higher education institution

Costa, Carolina and Alvelos, Helena and Teixeira, Leonor

International Journal of Online Pedagogy and Course Design

IGI Global

This article analyses the use and acceptance of technologies by professors in the teaching and learning context in a higher education institution. In the empirical study, a questionnaire based on the technology acceptance model was applied. The results indicated that the most used technologies are Moodle, Facebook and YouTube and it was concluded that in general, those technologies are well accepted. Few statistically significant differences between respondents’ gender, scientific areas or ages were found, revealing that the use of those technologies is already widespread in the studied institution. Results also showed that perceived usefulness and perceived ease of use are two important determinants of Moodle acceptance, and that the majority of respondents did not know the MOOC concept. This article is valuable for researchers in the area and for professors that want to implement the use technologies in the teaching and learning context. | doi | Peer Reviewed

25.  Optimal control measures for a susceptible‐carrier‐infectious‐recovered‐susceptible malware propagation model

Gonçalves, João N.C. and Rodrigues, Helena Sofia and Monteiro, M. Teresa T.

Optimal Control Applications and Methods


Purposing to lessen malware propagation, this paper proposes optimal control measures for a susceptible-carrier-infectious-recovered-susceptible (SCIRS) epidemiological model formed by a system of ordinary differential equations. By taking advantage of real-world data related to the number of reported cybercrimes in Japan from 2012 to 2017, an optimal control problem is formulated to minimize the number of infected devices in a cost-effective way. The existence and uniqueness of the results related to the optimality system are proved. Overall, numerical simulations show the usefulness of the proposed control strategies in reducing the spread of malware infections. | doi | Peer Reviewed

24.  Multiscale information storage of linear long-range correlated stochastic processes

Faes, Luca and Pereira, Margarida Almeida and Silva, Maria Eduarda and Pernice, Riccardo and Busacca, Alessandro and Javorka, Michal and Rocha, Ana Paula

Physical review. E

American Physical Society

Information storage, reflecting the capability of a dynamical system to keep predictable information during its evolution over time, is a key element of intrinsic distributed computation, useful for the description of the dynamical complexity of several physical and biological processes. Here we introduce a parametric approach which allows one to compute information storage across multiple timescales in stochastic processes displaying both short-term dynamics and long-range correlations (LRC). Our analysis is performed in the popular framework of multiscale entropy, whereby a time series is first "coarse grained" at the chosen timescale through low-pass filtering and downsampling, and then its complexity is evaluated in terms of conditional entropy. Within this framework, our approach makes use of linear fractionally integrated autoregressive (ARFI) models to derive analytical expressions for the information storage computed at multiple timescales. Specifically, we exploit state space models to provide the representation of lowpass filtered and downsampled ARFI processes, from which information storage is computed at any given timescale relating the process variance to the prediction error variance. This enhances the practical usability of multiscale information storage, as it enables a computationally reliable quantification of a complexity measure which incorporates the effects of LRC together with that of short-term dynamics. The proposed measure is first assessed in simulated ARFI processes reproducing different types of autoregressive dynamics and different degrees of LRC, studying both the theoretical values and the finite sample performance. We find that LRC alter substantially the complexity of ARFI processes even at short timescales, and that reliable estimation of complexity can be achieved at longer timescales only when LRC are properly modeled. Then, we assess multiscale information storage in physiological time series measured in humans during resting state and postural stress, revealing unprecedented responses to stress of the complexity of heart period and systolic arterial pressure variability, which are related to the different role played by LRC in the two conditions. | doi | Peer Reviewed

23.  Maximum entropy: a stochastic frontier approach for electricity distribution regulation

Silva, Elvira and Macedo, Pedro and Soares, Isabel

Journal of Regulatory Economics


The literature on incentive-based regulation in the electricity sector indicates that the size of this sector in a country constrains the choice of frontier methods as well as the model specification itself to measure economic efficiency of regulated firms. The aim of this study is to propose a stochastic frontier approach with maximum entropy estimation, which is designed to extract information from limited and noisy data with minimal statements on the data generation process. Stochastic frontier analysis with generalized maximum entropy and data envelopment analysis – the latter one has been widely used by national regulators – are applied to a cross-section data on thirteen European electricity distribution companies. Technical efficiency scores and rankings of the distribution companies generated by both approaches are sensitive to model specification. Nevertheless, the stochastic frontier analysis with generalized maximum entropy results indicate that technical efficiency scores have similar distributional properties and these scores as well as the rankings of the companies are not very sensitive to the prior information. In general, the same electricity distribution companies are found to be in the highest and lowest efficient groups, reflecting weak sensitivity to the prior information considered in the estimation procedure. | doi | Peer Reviewed

22.  Item pre-knowledge true prevalence in clinical anatomy- application of gated item response theory model

Severo, Milton and Silva-Pereira, Fernanda and Ferreira, Maria Amélia and Monteiro, Magda and Pereira, Isabel

BMC Medical Education

Springer Nature

Background: Computer and paper examinations in our days are constructed from an item pool which is regularly updated. Given the way that exams are created, one of the major concerns is the security of the items that are being used in order to ensure a good estimation of abilities. The aim of this study is to measure the prevalence of item pre-knowledge in our medical school. Methods: The Deterministic, Gated Item Response Theory Model (DGM) was applied to estimate the prevalence of students who have had item pre-knowledge from six multiple choice examinations of the Clinical Anatomy course at the Faculty of Medicine of University of Porto. Each examination consisted of 100 items with an average of 200 students and 20% repeated items per examination. The estimation of the sensitivity and specificity was based on a simulation study. The sensitivity and specificity estimates, and apparent prevalence were used to estimate true prevalence of cheating students in the examinations under study. Results: The specificity in the DGM for different simulation scenarios was between 68 and 98%, while the sensitivity ranged from 60 to 91%. The apparent prevalence was between 0.0 and 3.4%, while the true prevalence ranged from 1.2 to 3.7%. Conclusions: The true prevalence was much lower compared to the students self-reported copying of responses from other students; however, it is important to keep monitoring the pre-knowledge prevalence in order to enforce measures in case an increase occurs. | doi | Peer Reviewed

21.  Bayesian outlier detection in non‐Gaussian autoregressive time series

Silva, Maria Eduarda and Pereira, Isabel and McCabe, Brendan

Journal of Time Series Analysis


This work investigates outlier detection and modelling in non-Gaussian autoregressive time series models with margins in the class of a convolution closed parametric family. This framework allows for a wide variety of models for count and positive data types. The article investigates additive outliers which do not enter the dynamics of the process but whose presence may adversely influence statistical inference based on the data. The Bayesian approach proposed here allows one to estimate, at each time point, the probability of an outlier occurrence and its corresponding size thus identifying the observations that require further investigation. The methodology is illustrated using simulated and observed data sets. | doi | Peer Reviewed

20.  Preference for death at home and associated factors among older people in the city of Belo Horizonte, Brazil

Jorge, Rafaela and Calanzani, Natália and Freitas, Adelaide and Nunes, Rui and Sousa, Liliana

Ciência & Saúde Coletiva

ABRASCO - Associação Brasileira de Saúde Coletiva

We examined people's preferences for place of death and identified factors associated with a home death preference. We asked a representative sample (N = 400) of older people (≥ 60 years) residents in the city of Belo Horizonte, about their preferences for place of death in a situation of serious illness with less than a year to live. Data were analyzed using binomial regression to identify associated factors. 52.2% indicate home as the preferred place of death. Five variables were associated with preference for death at home: those living with 1 child (odds ratio (OR)0.41; 95% confidence interval (CI):0.18-0.92; ref: without children); being in education for up to 4 years (OR0.42; 95% CI:0.20-0.89; ref: higher education); finding it difficult to live with the present income (OR3.18; 95% CI:1.53-6.62; ref: living comfortably); self-assessed fair overall health (OR2.07; 95% CI:1.06-4.03; ref: very good health) and selecting "choosing who makes decisions about your care" as the care priority that would matter to them the most (OR2.43; 95%CI:1.34-4.40; ref: dying in the place you want). Most respondents chose home as preferred place of death. However, most residents of Belo Horizonte die in hospitals, suggesting that preferences are not being considered. | doi | Peer Reviewed

19.  Reliability and validity evidence of the Assessment of Language Use in Social Contexts for Adults (ALUSCA)

Valente, Ana Rita S. and Hall, Andreia and Alvelos, Helena and Leahy, Margaret and Jesus, Luis M. T.

Logopedics Phoniatrics Vocology

Taylor & Francis

Background: The appropriate use of language in context depends on the speaker's pragmatic language competencies. A coding system was used to develop a specific and adult-focused self-administered questionnaire to adults who stutter and adults who do not stutter, The Assessment of Language Use in Social Contexts for Adults, with three categories: precursors, basic exchanges, and extended literal/non-literal discourse. This paper presents the content validity, item analysis, reliability coefficients and evidences of construct validity of the instrument. Methods: Content validity analysis was based on a two-stage process: first, 11 pragmatic questionnaires were assessed to identify items that probe each pragmatic competency and to create the first version of the instrument; second, items were assessed qualitatively by an expert panel composed by adults who stutter and controls, and quantitatively and qualitatively by an expert panel composed by clinicians. A pilot study was conducted with five adults who stutter and five controls to analyse items and calculate reliability. Construct validity evidences were obtained using the hypothesized relationships method and factor analysis with 28 adults who stutter and 28 controls. Results: Concerning content validity, the questionnaires assessed up to 13 pragmatic competencies. Qualitative and quantitative analysis revealed ambiguities in items construction. Disagreement between experts was solved through item modification. The pilot study showed that the instrument presented internal consistency and temporal stability. Significant differences between adults who stutter and controls and different response profiles revealed the instrument's underlying construct. Conclusion: The instrument is reliable and presented evidences of construct validity. | doi | Peer Reviewed

18.  Construção e interpretação de diagramas de extremos e quartis por alunos portugueses do 9.° ano de escolaridade

Carvalho, Maria José and Fernandes, José António and Freitas, Adelaide

Bolema: Boletim de Educação Matemática

Universidade Estadual Paulista

This study deals with the difficulties of 9th grade Portuguese students in the building and interpreting of boxplots (DEQ). The study is based on the responses given by 93 9th grade students to 2 questions on the DEQ in a written diagnostic test. By examining the configurations of the objects and mathematical processes that intervene in the students' resolutions, we have identified discrepancies between the personal meanings reached by the students and the institutional meanings intended in the construction and interpretation of the DEQ, noting that: (i) in the construction of the DEQ we observed confusions in the form of presenting a DEQ by incorporating its numeric support in the diagram itself, and difficulties in the accuracy to be considered for the support scale of the support when the data's variation domain is greater; and (ii) in the interpretation of DEQ, there are clear difficulties in analyzing the distributional form of the data through a DEQ, observing the tendency for the student to respond based on the intuitive perception of the symmetry and dispersion of the distribution, without resorting to statistical measures in their justifications. We also observed that the construction of the DEQ is easier than its interpretation. These results corroborate the idea that the analysis of aggregate data, using DEQ, is not an easy task to understand by students of this level of education, so we suggest a greater articulation between DEQ construction activities and interpretation activities. | doi | Peer Reviewed

17.  Comparing traditional and tablet-based intervention for children with speech sound disorders: a randomised control trial

Jesus, Luis M. T. and Martinez, Joana and Santos, Joaquim and Hall, Andreia and Joffe, Victoria

Journal of Speech, Language, and Hearing Research

American Speech-Language-Hearing Association

Purpose: This article reports on the effectiveness of a novel tablet-based approach to phonological intervention and compares it to a traditional tabletop approach, targeting children with phonologically based speech sound disorders (SSD). Method: Twenty-two Portuguese children with phonologically based SSD were randomly assigned to 1 of 2 interventions, tabletop or tablet (11 children in each group), and received intervention based on the same activities, with the only difference being the delivery. All children were treated by the same speech-language pathologist over 2 blocks of 6 weekly sessions, for 12 sessions of intervention. Participants were assessed at 3 time points: baseline; pre-intervention, after a 3-month waiting period; and post-intervention. Outcome measures included percentage of consonants correct, percentage of vowels correct, and percentage of honemes correct. A generalization of target sounds was also explored. Results: Both tabletop and tablet-based interventions were effective in improving percentage of consonants correct and percentage of phonemes correct scores, with an intervention effect only evident for percentage of vowels correct in the tablet group. Change scores across both interventions were significantly greater after the intervention, compared to baseline, indicating that the change was due to the intervention. High levels of generalization (60% and above for the majority of participants) were obtained across both tabletop and tablet groups. Conclusions: The software proved to be as effective as a traditional tabletop approach in treating children with phonologically based SSD. These findings provide new evidence regarding the use of digital materials in improving speech in children with SSD. Supplemental Material: | doi | Peer Reviewed

16.  Using mathematical magic to improve student’s motivation in mathematics classes

Pais, Sónia and Hall, Andreia

Indagatio Didactica

Centro de Investigação Didática e Tecnologia na Formação de Formadores (CIDTFF/UA)

One of the problems identified in the failure of mathematics teaching is the lack of motivation that students feel towards the discipline. Considering that it is imperative to make the teaching and learning processes of mathematics more stimulating, taking into account modern society and student’s interests, the authors have developed several strategies to increase the interest and improve the success of students in mathematics. Thus, they decided to use mathematical magic tricks in their classes to raise the motivation of the students, captivating them and stimulating their interest in mathematics. In this work, a case study to evaluate how mathematical magic can contribute to increase students’ motivation for learning mathematics is presented. In order to develop this experience, the techniques of inquiry, direct observation and analysis of documents were applied and the following instruments were used: questionnaires and respective analysis grids; production of a battery of tasks of a diversified nature and field notes. The analysis of the collected data allows us to conclude that the use of mathematical magic tricks in the classroom, with the purpose of motivating the students to learn mathematics, revealed to be effective. | Peer Reviewed

15.  Selection and Application of graphical and numerical statistical tools by prospective primary school teachers

Fernandes, José António and Freitas, Adelaide

Acta Scientiae

Universidade Luterana do Brasil

Teaching statistics in the early years requires that teachers at this school level develop skills to analyze small collections of data. Given a collection of quantitative data (12 observations), in this paper we looked at how students and prospective primary school teachers select and make appropriate graphs and identify and determine statistical measures suitable for summarizing the data, including the interpretation of the third quartile. The study involved 50 students who were attending the 2nd year of the Basic Education Bachelor’s program at a university in northern Portugal. The collected data correspond to the answers given by the students in a formal examination in a Probability and Statistics course. An analysis of the answers showed that the students had difficulties in both the selection and application of statistical methods, which were more pronounced when they had to identify the appropriate graphs to represent the data and to determine the quartiles and to interpret the third quartile, and less pronounced in the case of determining other statistical measures. | doi | Peer Reviewed

14.  Distribution of distances between symmetric words in the human genome: analysis of regular peaks

Bastos, Carlos A. C. and Afreixo, Vera and Rodrigues, João M. O. S. and Pinho, Armando J. and Silva, Raquel M.

Interdisciplinary Sciences: Computational Life Sciences

Springer Verlag

Finding DNA sites with high potential for the formation of hairpin/cruciform structures is an important task. Previous works studied the distances between adjacent reversed complement words (symmetric word pairs) and also for non-adjacent words. It was observed that for some words a few distances were favoured (peaks) and that in some distributions there was strong peak regularity. The present work extends previous studies, by improving the detection and characterization of peak regularities in the symmetric word pairs distance distributions of the human genome. This work also analyzes the location of the sequences that originate the observed strong peak periodicity in the distance distribution. The results obtained in this work may indicate genomic sites with potential for the formation of hairpin/cruciform structures. | doi | Peer Reviewed

13.  Meta-analysis of the prevalence and risk factors associated with bovine neosporosis

Ribeiro, Claudia Mello and Soares, Isabela Ribeiro and Mendes, Rodrigo Guerrero and Bastos, Paula Andrea de Santis and Katagiri, Satie and Zavilenski, Renato Bacarin and Abreu, Hudson Felipe Porto de and Afreixo, Vera

Tropical Animal Health and Production


Neospora caninum is one of the main infectious agents that cause reproductive disorders in cattle. However, knowledge about the prevalence and causal factors of bovine neosporosis is needed in order to establish control measures. The purpose of this study was to estimate the pooled prevalence and determine the risk factors of bovine neosporosis using meta-analytic methods. Searches for data on N. caninum seroprevalence and potential risk factors were conducted in the PubMed, LILACS, and SciElo databases. The random effects model was used for the meta-analysis of the included studies. The pooled prevalence of N. caninum in cattle was 24% (95% confidence interval (CI), 19-29) in North and Central America, 24% (95% CI, 20-28) in South America, 18% (95% CI, 14-21) in Asia, 15% (95% CI, 12-18) in Europe, 13% (95% CI, 11-16) in Africa, and 8% (95% CI, 4-14) in Oceania. A significant correlation was found between N. caninum infection and abortion in cows (odds ratio (OR) = 2.66, 95% CI, 1.97-3.59). The following risk factors were signicantly associated with N. caninum seroprevalence: presence of dogs on the farm (OR = 2.84; 95% CI, 1.40-5.80) and the type of cattle production system, with dairy cattle being more susceptible to bovine neosporosis (OR = 1.60; 95% CI, 1.16-2.19) than beef cattle. The adoption of measures to prevent the dissemination of N. caninum in cattle herds is suggested, aiming to reduce the economic losses incurred to the dairy and beef industry. | doi | Peer Reviewed

12.  L-TRUST: long-term risk of cancer in patients under statins therapy: a systematic review and meta-analysis

Craveiro, Nuno Sales and Lopes, Bruno Silva and Tomás, Lara and Almeida, Sofia Fraga and Palma, Helena and Afreixo, Vera and Matos, Luís Costa

Pharmacoepidemiology and Drug Safety


Statins are widely prescribed drugs with established efficacy in primary and secondary prevention of cardiovascular events. Although they are mostly well tolerated, several authors have been emphasizing that the statins' safety profile is not totally clarified especially when considering risk of cancer in patients with long-term exposure to statins. This meta-analysis was aimed at evaluating the risk of cancer in patients with prolonged exposure to statins. | doi | Peer Reviewed

11.  Effects of physical exercise on outcomes of cardiac (dys)function in women with breast cancer undergoing anthracycline or trastuzumab treatment: study protocol for a systematic review

Antunes, Pedro and Esteves, Dulce and Nunes, Célia and Amarelo, Anabela and Fonseca-Moutinho, José and Afreixo, Vera and Costa, Henrique and Alves, Alberto and Joaquim, Ana

Systematic Reviews


Background: Cardiotoxicity is a known complication and one of the most adverse effects from the use of conventional treatments such as anthracyclines and trastuzumab in breast cancer (BC) care. This phenomenon has been associated with the restriction of therapeutic options and the increase of cardiovascular complications, which may compromise the survival of patients. Implementation of preventive strategies is an important approach for the management of this issue. Physical exercise has been proposed as a non-pharmacological strategy to counteracting cardiotoxicity. The aim of this protocol is to describe the rationale and methods for a systematic review of published randomized controlled trials (RCTs) that have analysed the effects of physical exercise on outcomes of cardiac (dys)function in women with BC undergoing neoadjuvant or adjuvant treatment containing anthracyclines and/or trastuzumab. Methods and analysis: This is a protocol for a systematic review reported according to the PRISMA-P 2015 checklist. Randomized controlled trials (RCTs) will be included. The literature will be screened on MEDLINE, EMBASE, the Cochrane Central Register of Controlled Trials, ISI Web of Science and Scopus. The risk of bias of the included RCTs will be assessed using the Cochrane Collaboration’s tool. The primary outcomes will be systolic function (left ventricular ejection fraction), diastolic function (E/A’ ratio, deceleration time of early left ventricular filling, isovolumetric relaxation time, E/E’ septal and lateral ratio) and myocardial deformation imaging outcomes (strain and strain rate [measured in longitudinal, radial, or circumferential directions]). Secondary outcomes will be cardiac biomarkers (troponin I or T, highsensitivity troponin I or T, brain natriuretic peptide, amino terminal of B-type natriuretic peptide). Data will be descriptively reported, and quantitative synthesis will also be considered if the included studies are sufficiently homogenous. Discussion: This systematic review will help to understand the effectiveness of physical exercise on counteracting cardiotoxicity related to anticancer therapies in women with BC. | doi | Peer Reviewed

10.  Meta-analysis of a very low proportion through adjusted wald confidence intervals

Afreixo, V. and Cruz, S. and Freitas, A. and Hernandez, M. A.

Open Access Biostatistics & Bioinformatics

Crimson Publishers

In this paper we will discuss the meta-analysis of one low proportion. It is well known, that there are several methods to perform the meta-analysis of one proportion, based on a linear combination of proportions or transformed proportions. However, in the context of a linear combination of binomial proportions has been proposed some approximate estimators with some improvements on low proportion estimation. In this paper we will show, with a simple adaptation, the possible contribution of several approximate adjusted Wald confidence intervals (CIs) for the meta-analysis of proportions. In the context of low proportions, a simulation study scenario is carried out to compare these CIs amongst themselves and with other available methods with respect to bias and coverage probabilities, using the fixed effect or the random-effects model. Pointing our interest in rare events (analogous for the abundant events) and taking into account the prevalence estimation of the Methicillin-resistant Staphylococcus aureus with mecc gene, we discuss the choice of the meta-analysis methods on this low proportion. The default meta-analysis methods of meta-analysis software programs are not always the best choice, in particular to the meta-analysis of one low proportion, where the methods including the adjusted Wald can outperform. | doi | Peer Reviewed


9.  Using an artistic approach to the teaching of non-euclidean geometry in a professional development course for mathematics teachers

Hall, Andreia and Brás, Isabel and Pais, Sónia

INTED 2019 Proceedings


Elliot Eisner (1933-2014), a pioneer in arts education, suggested that an artistic approach to education could improve its quality and lead to a new vision for teaching and learning [1]. This is true for any subject, including mathematics. Geometry related topics make a perfect setting for a deeper contribution of art to education and allow for a complete symbiosis between the teaching of mathematics and an artistic education. One such topic is the study of non-Euclidean geometry which is now briefly addressed in the middle school mathematics curriculum in Portugal [2]. We believe that the learning and teaching of non-Euclidean geometry can be facilitated by taking the role of an artist and creating works of art, eventually inspired by renowned artists such as M.C. Escher. In this paper, we present some results of a professional development course for mathematics teachers where the participants studied basic non-Euclidean geometry concepts and created ceramic pieces using the Poincaré disk. The course took place in a Portuguese university, from January to March 2018, and involved 20 teachers of grades 1 to 12. The authors have developed a qualitative case study to evaluate how an artistic approach to the teaching of non-Euclidean geometry is perceived, by the mathematics teachers, as a contribution to the learning process. Overall, the activities developed have proved to be successful examples of interdisciplinary methodologies that bring into the teaching of mathematics usual procedures in the teaching of the arts. Moreover, the artistic approach followed during the course helped the teachers develop their geometric competences concerning non-Euclidean geometry in a more solid appropriation and application of the geometric concepts involved. | Peer Reviewed

8.  Mathematical magic in undergraduate mathematical classes for pre-service teachers

Hall, Andreia and Pais, Sónia

INTED 2019 Proceedings


Nowadays we live in an ever-changing society. The educational context is no exception, and requires a renewal of paradigms. Profound changes to the role and function of the teacher and the students are particularly vital [1], [2], [3]. The current University students have different motivations, different attitudes towards the teaching and learning process, and different responses to specific classroom environments and instructional practices [4]. The challenge that teachers face today is to motivate students to learn, get them to commit to and have an active role in their learning [5]. Considering that it is imperative to make the teaching and learning process of mathematics more stimulating, taking into account modern society and student’s interests [6], the authors have developed several strategies to increase the interest and improve the success of students in mathematics. Thus, they decided to use mathematical magic tricks in their classes to raise the motivation of the students, captivating them and stimulating their interest in mathematics. In this work, a case study to evaluate how mathematical magic can contribute to increase students' motivation for learning mathematics is presented. The paper describes how it is conceived as well as the main results. | Peer Reviewed

7.  Dificuldades de alunos do 8.º ano na construção de diagramas de extremos e quartis

Carvalho, Maria José and Fernandes, José António and Freitas, Adelaide

Actas del Tercer Congreso Internacional Virtual de Educación Estadística

Universidad de Granada, Facultad de Ciencias de la Educacion

Neste estudo são analisadas as resoluções de 23 alunos portugueses, do 8.º ano, de tarefas sobre o tema diagramas de extremos e quartis (DEQ) quando os dados são fornecidos de duas formas distintas: dados não organizados e dados representados num... | Peer Reviewed

6.  Analyzing the practices of knowledge sharing and collaboration considering faculty members and researchers: an empirical study

Chedid, Marcello and Alvelos, Helena and Teixeira, Leonor

INTED2019 Proceedings - 13th International Technology, Education and Development Conference


Knowledge sharing and collaboration among university researchers and/or teachers are impacted by: (i) life cycles associated with technological innovations; (ii) economic and cultural globalization; (iii) the educational needs of an increasingly knowledge-driven society; and (iv) the training needs for highperforming professional activities. These factors constitute major opportunities for change in higher education institutions around the world and can be found in internal and/or external collaboration relationships. A collaboration relationship is expected to benefit the related members and teams (teachers, researchers, students and professionals), the communities/organizations that establish the relationship and, consequently, the surrounding society. Several studies reveal that collaboration can be strongly influenced by knowledge sharing. However, often universities evidence an individualistic culture where knowledge is related to the experience and the competence of each researcher and/or teacher. Thus, knowledge is frequently considered as property and as a differentiation factor of each individual. Additionally, the perception of little benefits and rewards in sharing knowledge within the institution lead to the existence of a real distance among the work of the referred actors, who focus their efforts towards individual objectives rather than in common goals. In this context, the individual characteristics tend to show a major impact on knowledge sharing. Considering the limited number of studies in the university’s context regarding knowledge sharing and collaboration practices, especially within Portuguese higher education institutions, the need to explore and deepen the understanding of these questions was identified. Taking this issue into account, this work aims at analyzing the practices of knowledge sharing and collaboration among researchers and/or teachers at the University of Aveiro, Portugal. The empirical study was conducted on the basis of a questionnaire prepared taking into account the literature on the area. The sample consisted of teachers and researchers from University of Aveiro, Portugal, and the questionnaire was provided online. The data was collected anonymously and analyzed with the statistical software SPSS IBM 24. The results present some important facts that can help higher education institutions and their members to define and implement strategies and practices in order to promote higher levels of knowledge sharing and stronger collaboration relationships. | doi | Peer Reviewed

5.  Forecasting temperature time series for irrigation planning problems

Costa, Cláudia and Gonçalves, A. Manuela and Costa, Marco and Lopes, Sofia O.

34th International Workshop on Statistical Modelling (IWSM 2019)


Climate change is a reality and efficient use of scarce resources is vital. The challenge of this project is to study the behaviour of humidity in the soil by mathematical/statistical modeling in order to find optimal solutions to improve the efficiency of daily water use in irrigation systems. For that, it is necessary to estimate and forecast weather variables, in this particular case daily maximum and minimum air temperature. These time series present strong trend and high- frequency seasonality. This way, we perform a state space modeling framework using exponential smoothing by incorporating Box-Cox transformations, ARMA residuals, Trend and Seasonality. | Peer Reviewed

4.  A note on the estimation of stochastic and deterministic production frontiers with maximum entropy

Macedo, Pedro

26th APDR Congress


Stochastic frontier analysis with maximum entropy estimation has received considerable attention in the literature in the recent years. In this work, the estimation of stochastic and deterministic production frontiers with maximum entropy methods, the advantages and disadvantages relatively to maximum likelihood, and some proposals to improve maximum entropy estimation in this context are presented and discussed. | Peer Reviewed

3.  An examination of food distribution and specialised retail sales in Portugal

Sério, Filipe and Costa, Marco and Ribeiro, Humberto

43rd International Scientific Conference on Economic and Social Development

Varazdin Development and Entrepreneurship Agency (VADEA)

The food retail sector in Portugal is mostly concentrated in five main players holding 69.6% of its market share, with two groups leading the Portuguese preference, Continente with 21.9% market share, Pingo Doce with 20.8% market share, followed by Jumbo, Lidl and Intermarché with 9.5%, 8.8% and 8.6%, respectively. These operators up to the year 2012 have guided their performance and price strategy by applying the strategy Every-day-Low-Price that privileges the application of low and stable prices. In this paper we aim to characterize the food retail market in Portugal after the year 2012, identifying the main factors and contextualizing the economic climate. This analysis takes into account that most retailers opted to follow a strategy of high low pricing, which determined that 47% of sales of the year 2018 correspond to promotional sales; in this way, we will devote the analysis of the promotion and the impacts that it has for forecasting sales and supply chain management. Thus, to evaluate the influence of promotions on global sales, we will use weekly data referring to sales in the hypermarkets & "Superstores" channel that includes hypermarkets> 2,500 m2; Supermarkets 400-2,500 m2; Proximity <400 m2, in the period between the first week of 2012 and the last week of 2018, and also data on the number of promotions printed on promotional leaflets on the same the period in question. Applying multiple linear regression models and a previous exploratory analysis of the data we can conclude that the promotions carried out via leaflets actions have a weak capacity to explain the sales obtained in the Hypermarkets & Superstores channel and that are explained in large scale by other variables and the impact of these variables should be object of study in future works. | Peer Reviewed

2.  Fuel retail market: assessing the determinants that influences the performance of sales of fuel stations

Espadilha, Stephanie and Costa, Marco and Magueta, Daniel

43rd International Scientific Conference on Economic and Social Development

Varazdin Development and Entrepreneurship Agency (VADEA)

The oil and energy sector is a very traditional, controversial and competitive sector. This study is based on a Portuguese fuel company and its main objective is to identify and characterize potential variables with predictive capacity for sales of new fuel stations. The database consists of a set of context variables with predictive potential for sales of fuel stations and monthly sales in terms of fuel volume. The research methodology focused on statistical methods of exploratory data analysis, clusters analysis and regression models. The fuel station context variables tend to characterize the socio-economic conditions of the area of influence of each station, such as population density variable, others related to the similar existing supply of both the company itself and the competing companies, and others related to geographical location and accessibility. The exploratory data analysis allowed to identify several patterns in the time series of sales indicating that the investigation of factors must be segmented. Homogeneous groups of fuel stations were identified through a hierarchical agglomerative clustering procedure considering the Ward's minimum variance method and the square Euclidian distance as distance measure. For each of the groups identified, multiple linear regression models were adjusted considering the annual fuel sales in the 1st, 2nd and 3rd years of operation of the stations as dependent variables. The results show that not all the exogenous variables are statistically significant. However, it is possible to conclude that the average daily traffic is the variable with predicted capacity for the most of the groups of fuel stations analyzed. | Peer Reviewed

1.  Interlacing mathematics and art: hands-on non-Euclidean geometry

Hall, Andreia and Brás, Isabel and Pais, Sónia

Proceedings of Bridges 2019: Mathematics, Art, Music, Architecture, Education, Culture

Tessellations Publishing

Elliot Eisner (1933-2014), a pioneer in arts education, suggested that an artistic approach to education could improve its quality and lead to a new vision for teaching and learning. This is true for any subject, including mathematics. Geometry related topics make a perfect setting for a deeper contribution of art to education. One such topic is the study of non-Euclidean geometry. In this paper, we present some results of a professional development course for mathematics teachers where the participants studied non-Euclidean geometry concepts. The participants created ceramic pieces using the Poincaré disk and styrofoam balls covered with fabrics using spherical geometry. | Peer Reviewed
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