Publications 2020

  1. Home
  2. Publications

Books


29.  Bioestatística: síntese teórica e exercícios

Freitas, Adelaide and Cruz, João Pedro

Edições Sílabo

Sem resumo disponível.

ria.ua.pt

Book Chapters


28.  A note on robust estimation of the extremal index

Miranda, M. Cristina Souto and Gomes, M. Ivette and Miranda, M. Manuela Souto

Nonparametric Statistics

Springer

Many examples in the most diverse fields of application show the need for statistical methods of analysis of extremes of dependent data. A crucial issue that appears when there is dependency is the reliable estimation of the extremal index (EI), a parameter related to the clustering of large events. The most popular EI-estimators, like the blocks’ EI-estimators, are very sensitive to anomalous cluster sizes and exhibit a high bias. The need for robust versions of such EI-estimators is the main topic under discussion in this paper.

ria.ua.pt | doi | Peer Reviewed

27.  Extremal index estimation: application to financial data

Miranda, Maria Cristina Souto

Handbook of Research on Accounting and Financial Studies

IGI Global

In finance it is crucial to understand the risk of occurrence of extreme events such as currency crises or stock market crashes. It is important to model the distribution of extreme events. Extreme value theory is known to accurately estimate quantiles and tail probabilities of financial asset returns. These kinds of data are usual related to heavy tailed distributions, where a relevant parameter is the tail index. Fitting data to heavy tail distributions usually assumes independent observations. However, the most usual real market scenario describes clusters of extreme events rather than isolated records over some period of time. In that case, estimating tail probabilities includes estimating the extremal index. This chapter describes the usual extremal index estimators based in different approaches and illustrates their values for a real financial data set. Computations are provided by the use of suitable R packages.

ria.ua.pt | doi | Peer Reviewed

26.  PLS visualization using biplots: an application to team effectivenes

Silva, Alberto and Dimas, Isabel Dórdio and Lourenço, Paulo Renato and Rebelo, Teresa and Freitas, Adelaide

Computational Science and Its Applications: ICCSA 2020

Springer Nature

Based on a factorization provided by the Partial Least Square (PLS) methodology, the construction of a biplot for both exploratory and predictive purposes was shown to visually identify patterns among response and explanatory variables in the same graph. An application on a team effectiveness research, collected from 82 teams from 57 Portuguese companies and their respective leaders, containing two effectiveness criteria (team performance and the quality of the group experience as response variables), was considered and interpretation of the biplot was analyzed in detail. Team effectiveness was considered as the result of the role played by thirteen variables: team trust (two dimensions), team psychological capital (four dimensions), collective behavior, transformational leadership, intragroup conflict (two dimensions), team psychological safety, and team cohesion (two dimensions). Results revealed that the biplot approach proposed was able to capture the most critical variables for the model and correctly assigned the signals and the strength of the regression coefficients. Regarding the response variable team performance, the most significant variables to the model were team efficacy, team optimism, and team psychological safety. Concerning the response variable quality of the group experience, intragroup conflict, team-trust, and team cohesion emerged as the most relevant predictors. Overall, the results found are convergent with the literature on team effectiveness.

ria.ua.pt | doi | Peer Reviewed

25.  Freedman’s paradox: a solution based on normalized entropy

Macedo, Pedro

Theory and applications of time series analysis

Springer

In linear regression models where there are no relationships between the dependent variable and each of the potential explanatory variables – a usual scenario in real-world problems – some of them can be identified as relevant by standard statistical procedures. This incorrect identification is usually known as Freedman's paradox. To avoid this disturbing effect in regression analysis, an info-metrics approach based on normalized entropy is discussed and illustrated in this work. As an alternative to traditional statistical methodologies currently used by practitioners, the simulation results suggest that normalized entropy is a powerful procedure to identify pure noise models.

ria.ua.pt | doi | Peer Reviewed

Articles


24.  Inventory models with reverse logistics for assets acquisition in a liquefied petroleum gas company

Lopes, Cristina and Correia, Aldina and Silva, Eliana Costa e and Monteiro, Magda and Lopes, Rui Borges

Journal of Mathematics in Industry

SpringerOpen

This paper addresses a case study regarding inventory models for acquiring liquefied petroleum gas (LPG) cylinders. This is an industrial challenge that was proposed at an European Study Group with Industry, by a Portuguese energy company, for which the LPG cylinder is the main asset of its LPG business. Due to the importance of this asset, an acquisition plan must be defined in order to determine the amount of LPG cylinders to acquire, and when to acquire them, in order to optimize the investment. As cylinders are returned and refilled, the reverse logistic flows of these assets must be considered. As the classical inventory models are not suitable for this case study, three new inventory models, which account for the return of LPG cylinders, are proposed in this work. The first proposed model considers deterministic constant demand and continuous returns of LPG cylinders, with discrete replenishment from the supplier. The second model is similar, but for the case when the returned cylinders cover for the demand. A third model is also proposed considering that both the demand and the returns are stochastic in nature and the replenishment from the supplier is discrete. The three models address different scenarios that the company is either currently facing or is expecting to occur in the near future.

ria.ua.pt | doi | Peer Reviewed

23.  Qualitatively-improved identified parameters of prestressed concrete catenary poles using sensitivity-based Bayesian approach

Alkam, F. and Pereira, I. and Lahmer, T.

Results in Engineering

Elsevier

Prestressed, spun-cast ultrahigh-strength concrete catenary poles have been used widely for electric train systems; for example, thousands of these poles have been installed along high-speed train tracks in Germany. Given the importance of the functionality of train systems, adequate attention has not been paid to catenary poles in research and the literature. Questions regarding the integrity of catenary poles still exist. This study contributes to identify the actual material properties of the poles of interest because the parameter identification is an essential process for any subsequent evaluation of the integrity of catenary poles. Accordingly, a sensitivity-based Bayesian parameter identification approach is developed to estimate the real material properties of the poles using measurements from multiple experiments and numerical models. This approach integrates the sensitivity of time-dependent measurements into the Bayesian inference, which improves the quality of inferred parameters considerably in comparison with classic Bayesian approaches applied in similar case of studies. Furthermore, the proposed approach combines observations of multiple experiments conducted on full-scale poles using a probabilistic uncertainty framework, which provides informative data used in the parameter identification process. Besides, Bayesian inference quantifies the uncertainty of inferred parameters and estimates the hyperparameters, such as the total errors of the observations. The proposed approach utilizes the efficiency of the transitional Markov Chain Monte Carlo algorithm for sampling from the posterior in both levels of Bayesian inference, namely, the unknown parameters and the hyperparameters. The results show the significant influence of the sensitivity concept in improving the quality of the posterior and highlight the importance of identifying the real material properties during the evaluation of the behavior of existing structures, rather than using the characteristic properties from the datasheet. Applying the proposed approach looks very promising when applied to similar applied case studies.

ria.ua.pt | doi | Peer Reviewed

22.  A multi-model methodology for forecasting sales and returns of liquefied petroleum gas cylinders

Correia, Aldina and Lopes, Cristina and Silva, Eliana Costa e and Monteiro, Magda and Lopes, Rui Borges

Neural Computing and Applications

Springer

In the liquefied petroleum gas (LPG) cylinder business, one of the most important assets is the LPG cylinder. This work addresses the asset acquisition planning for the LPG cylinder business of a company from the energy sector which has recently started this activity. In order to make the acquisition plan, it was necessary to forecast the sales and the LPG cylinder return rate. For that purpose, an ensemble method using time series techniques, multiple linear regression models and artificial neural networks was employed. Sales forecast was obtained using time series techniques, in particular, moving averages and exponential smoothing. Then, forecast of bottled propane gas sales and return rate was also addressed through multiple linear regression and artificial neural networks. A probability density function was defined for each of the different approaches. Afterward, using Monte Carlo simulation, the forecast values are obtained by a linear combination of the probability density functions, thus producing the final forecast. Results show that the company’s expectation of growth is larger than that predicted by the proposed methodology, which means the company should reflect on its current asset acquisition strategy. By combining different approaches, the proposed multi-model methodology allowed to obtain an accurate forecasting, without requiring a lot of historical data.

ria.ua.pt | doi | Peer Reviewed

21.  Time Series components separation based on Singular Spectral Analysis visualization: an HJ-biplot method application

Silva, Alberto Oliveira da and Freitas, Adelaide

Statistics, Optimization and Information Computing

International Academic Press

The extraction of essential features of any real-valued time series is crucial for exploring, modeling and producing, for example, forecasts. Taking advantage of the representation of a time series data by its trajectory matrix of Hankel constructed using Singular Spectrum Analysis, as well as of its decomposition through Principal Component Analysis via Partial Least Squares, we implement a graphical display employing the biplot methodology. A diversity of types of biplots can be constructed depending on the two matrices considered in the factorization of the trajectory matrix. In this work, we discuss the called HJ-biplot which yields a simultaneous representation of both rows and columns of the matrix with maximum quality. Interpretation of this type of biplot on Hankel related trajectory matrices is discussed from a real-world data set.

ria.ua.pt | doi | Peer Reviewed

20.  Older people’s preferences for self-involvement in decision-making if faced with serious illness

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

Geriatrics, Gerontology and Aging

Brazilian Society of Geriatrics and Gerontology (SBGG)

OBJECTIVES: To examine older people’s preferences for self-involvement in end-of-life care decision-making in scenarios of mental capacity (competency) and incapacity, and to identify associated factors. METHODS: A cross-sectional survey was conducted including 400 individuals aged 60+ years living in the city of Belo Horizonte, Brazil. RESULTS: Among 400 respondents, 95.3% preferred self-involvement when capable (due to the high percentage, associated factors were not calculated) and 64.5% preferred self-involvement when incapable through, for example, a living will. Considering that participants could choose multiple answers, the most frequent combinations in the capacity scenario were “yourself” and “other relatives” (76.8%) and “yourself” and “the doctor” (67.8%). In the incapacity scenario, the most frequent combinations were “yourself” and “other relatives” (usually their “ children and, less often, their grandchildren) (59.3%) and “yourself” and “the doctor” (48.5%). Three factors were associated with a preference for self-involvement in an incapacity scenario. Those who were married or had a partner (widowed; adjusted odds ratio [AOR] = 0.37; 95% confidence interval [CI] 0.19-0.68) and those who were male (female; AOR = 0.62; 95%CI 0.38-1.00) were less likely to prefer self-involvement. Those who were younger, as in age bands 60-69 years (80+; AOR = 2.35; 95%CI 1.20-4.58) and 70-79 years (80+; AOR = 2.45; 95%CI 1.21-4.94), were more likely to prefer self-involvement. CONCLUSIONS: Most participants preferred self-involvement in both scenarios of capacity and incapacity. Preference for self-involvement was higher in the scenario of capacity, while preference for the involvement of other relatives (usually their children) was greater in the scenario of incapacity.

ria.ua.pt | doi | Peer Reviewed

19.  Inference for bivariate integer-valued moving average models based on binomial thinning operation

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

Journal of Applied Statistics

Taylor & Francis

Time series of (small) counts are common in practice and appear in a wide variety of fields. In the last three decades, several models that explicitly account for the discreteness of the data have been proposed in the literature. However, for multivariate time series of counts several difficulties arise and the literature is not so detailed. This work considers Bivariate INteger-valued Moving Average, BINMA, models based on the binomial thinning operation. The main probabilistic and statistical properties of BINMA models are studied. Two parametric cases are analysed, one with the cross-correlation generated through a Bivariate Poisson innovation process and another with a Bivariate Negative Binomial innovation process. Moreover, parameter estimation is carried out by the Generalized Method of Moments. The performance of the model is illustrated with synthetic data as well as with real datasets.

ria.ua.pt | doi | Peer Reviewed

18.  New developments in the forecasting of monthly overnight stays in the North Region of Portugal

Silva, Isabel and Alonso, Hugo

Journal of Applied Statistics

Taylor & Francis

The Tourism sector is of strategic importance to the North Region of Portugal and is growing. Forecasting monthly overnight stays in this region is, therefore, a relevant problem. In this paper, we analyze data more recent than those considered in previous studies and use them to develop and compare several forecasting models and methods. We conclude that the best results are achieved by models based on a non-parametric approach not considered so far for these data, the singular spectrum analysis.

ria.ua.pt | doi | Peer Reviewed

17.  Small-scale distribution of microbes and biogeochemistry in the Great Barrier Reef

Carreira, Cátia and Carvalho, Júlia Porto Silva and Talbot, Samantha and Pereira, Isabel and Lønborg, Christian

PeerJ

PeerJ

Microbial communities distribute heterogeneously at small-scales (mm-cm) due to physical, chemical and biological processes. To understand microbial processes and functions it is necessary to appreciate microbes and matter at small scales, however, few studies have determined microbial, viral, and biogeochemical distribution over space and time at these scales. In this study, the small-scale spatial and temporal distribution of microbes (bacteria and chlorophyll a), viruses, dissolved inorganic nutrients and dissolved organic carbon were determined at five locations (spatial) along the Great Barrier Reef (Australia), and over 4 consecutive days (temporal) at a coastal location. Our results show that: (1) the parameters show high small-scale heterogeneity; (2) none of the parameters measured explained the bacterial abundance distributions at these scales spatially or temporally; (3) chemical (ammonium, nitrate/nitrite, phosphate, dissolved organic carbon, and total dissolved nitrogen) and biological (chl a, and bacterial and viral abundances) measurements did not reveal significant relationships at the small scale; and (4) statistically significant differences were found between sites/days for all parameter measured but without a clear pattern.

ria.ua.pt | doi | Peer Reviewed

16.  A comprehensive analysis of age and gender effects in European Portuguese oral vowels

Albuquerque, Luciana and Oliveira, Catarina and Teixeira, António and Sá-Couto, Pedro and Figueiredo, Daniela

Journal of Voice

Elsevier

The knowledge about the age effects in speech acoustics is still disperse and incomplete. This study extends the analyses of the effects of age and gender on acoustics of European Portuguese (EP) oral vowels, in order to complement initial studies with limited sets of acoustic parameters, and to further investigate unclear or inconsistent results. A database of EP vowels produced by a group of 113 adults, aged between 35 and 97, was used. Duration, fundamental frequency (f0), formant frequencies (F1 to F3), and a selection of vowel space metrics (F1 and F2 range ratios, vowel articulation index [VAI] and formant centralization ratio [FCR]) were analyzed. To avoid the arguable division into age groups, the analyses considered age as a continuous variable. The most relevant age-related results included: vowel duration increase in both genders; a general tendency to formant frequencies decrease for females; changes that were consistent with vowel centralization for males, confirmed by the vowel space acoustic indexes; and no evidence of F3 decrease with age, in both genders. This study has contributed to knowledge on aging speech, providing new information for an additional language. The results corroborated that acoustic characteristics of speech change with age and present different patterns between genders.

ria.ua.pt | doi | Peer Reviewed

15.  The effect of an exercise intervention program on bone health after bariatric surgery: a randomized controlled trial

Diniz-Sousa, Florêncio and Veras, Lucas and Boppre, Giorjines and Sá-Couto, Pedro and Devezas, Vítor and Santos-Sousa, Hugo and Preto, John and Vilas-Boas, João Paulo and Machado, Leandro and Oliveira, José and Fonseca, Hélder

Journal of Bone and Mineral Research

Wiley; American Society for Bone and Mineral Research

Exercise has been suggested as a therapeutic approach to attenuate bone loss induced by bariatric surgery (BS), but its effectiveness remains unclear. Our aim was to determine if an exercise-training program could induce benefits on bone mass after BS. Eighty-four patients, submitted to gastric bypass or sleeve gastrectomy, were randomized to either exercise (EG) or control group (CG). One month post-BS, EG underwent a 11-month supervised multicomponent exercise program, while CG received only standard medical care. Patients were assessed before BS and at 1, 6, and 12 months post-BS for body composition, areal bone mineral density (BMD), bone turnover markers, calciotropic hormones, sclerostin, bone material strength index, muscle strength, and daily physical activity. A primary analysis was conducted according to intention-to-treat principles and the primary outcome was the between-group difference on lumbar spine BMD at 12 months post-BS. A secondary analysis was also performed to analyze if the exercise effect depended on training attendance. Twelve months post-BS, primary analysis results revealed that EG had a higher BMD at lumbar spine (+0.024 g∙cm-2 [95% confidence interval (CI) 0.004, 0.044]; p = .015) compared with CG. Among total hip, femoral neck, and 1/3 radius secondary outcomes, only 1/3 radius BMD improved in EG compared with CG (+0.013 g∙cm-2 [95% CI 0.003, 0.023]; p = .020). No significant exercise effects were observed on bone biochemical markers or bone material strength index. EG also had a higher lean mass (+1.5 kg [95% CI 0.1, 2.9]; p = .037) and higher number of high impacts (+51.4 [95% CI 6.6, 96.1]; p = .026) compared with CG. In addition, secondary analysis results suggest that exercise-induced benefits may be obtained on femoral neck BMD but only on those participants with ≥50% exercise attendance compared with CG (+5.3% [95% CI 2.0, 8.6]; p = .006). Our findings suggest that an exercise program is an effective strategy to ameliorate bone health in post-BS patients. © 2020 American Society for Bone and Mineral Research (ASBMR).

ria.ua.pt | doi | Peer Reviewed

14.  Nursing workload assessment in an intensive care unit: a 5-year retrospective analysis

Simões, João Lindo and SáCouto, Pedro and Simões, Carlos Jorge and Oliveira, Cátia and Santos, Neuza Maia dos and Mateus, José and Magalhães, Carlos and Martins, Matilde

Journal of Clinical Nursing

Wiley

Aims: To study the correlation between the workload of intensive care nursing teams and the sociodemographic, anthropometric and clinical characteristics of patients in critical condition in a Portuguese Intensive Care Unit (ICU) during a 5‐year period. Background: Currently, indices of nursing workload quantification are one of the resources used for planning and evaluating ICUs. Evidence shows that there are several factors related to critical patients and their hospitalisation which potentially influence the nursing workload. Design: Retrospective cohort analysis of a health record database from adult patients admitted to a Portuguese ICU between January 1, 2015, and December 31, 2019. Methods: Simplified Therapeutic Intervention Scoring System (TISS‐28) scores of 730 adult patients. Three TISS‐28 assessments were considered: first assessment, last assessment and average. The STROBE guidelines were used in reporting this study. Results: The TISS‐28 has an average of 34.2 ± 6.9 points at admission, which is considered a high nursing workload. A somewhat lower result was found for the discharge and average assessments. It shows that basic activities accounted for the highest percentage of time spent (38.0%), followed by the cardiovascular support category (26.5%). The TISS‐28 shows consistent results throughout the study period, despite a small trend reduction in the last 2 years. Conclusions: Lower workloads were found for age ≤ 44 years and with a shorter length of stay. Higher workload was more probable in patients classified in Cullen Class IV (OR = 2.5) and with a normal to higher weight percentile (OR = 1.9 and 1.5, respectively). Relevance to clinical practice: Knowledge of the factors influencing the nursing workload facilitates the implementation of rules to improve performance in nursing interventions, based on the redefinition of care priorities, increased productivity, human resources management and reduction of additional costs to the organisation, related to possible adverse events, among others.

ria.ua.pt | doi | Peer Reviewed

13.  Effects of a short health education intervention on physical activity, arterial stiffness and cardiac autonomic function in individuals with moderate-to-high cardiovascular risk

Bohn, Lucimére and Sá-Couto, Pedro and Castro, Ana Ramoa and Ribeiro, Fernando and Oliveira, José

Patient Education and Counseling

Elsevier

Objective: This study evaluated the effects of a short health education and counseling intervention program, in a primary healthcare setting, on daily physical activity (PA), arterial stiffness, and cardiac autonomic function in individuals with moderate-to-high risk of cardiovascular disease. Methods: This was a parallel-group study with a 4-month-long intervention, plus 8 months of follow-up. 164 individuals with moderate-to-high cardiovascular risk were allocated to either an intervention (n = 87) or a control group (n = 77). The intervention consisted of 3 walking and face-to-face group sessions plus text messages. Primary outcome was daily PA (sedentary time, light and moderate-to-vigorous PA, all in min/day); secondary outcomes were arterial stiffness i.e., carotid-femoral pulse wave velocity (cfPWV, m/s)] and cardiac autonomic function [(i.e., standard deviation of all N-N intervals (SDNN, ms) and absolute high frequency (HF, ms2)]. Results: There were not significant group*time interactions for sedentary time [−7.4 (7.6); p = 0.331)], light PA [4.4 (6.4); p = 0.491] or moderate-to-vigorous PA [0.1 (2.6); p = 0.938]. Considering secondary outcomes, there were not significant group*time interactions for cfPWV [0.09 (0.18); p = 0.592], Ln_SDNN [0.09 (0.06); p = 0.148], or Ln_HF [0.16 (0.14); p = 0.263]. Conclusion: The program did not improve daily PA, arterial stiffness, or the autonomic cardiac function. Practice Implications: Primary care staff should consider longer or other types of intervention to improve daily PA.

ria.ua.pt | doi | Peer Reviewed

12.  Simulation of image-guided intervention in medical imaging education

Carramate, Lara F. N. D. and Rodrigues, Alexandre and Simões, João Lindo and Sá-Couto, Pedro and Pereira, Rui M. and Pinto, Serafim and Francesco, Silvia de

Journal of Medical Imaging and Radiation Sciences

Elsevier

Introduction/Background: Medical imaging education programs across Europe, despite their variability, include clinical practice as a guarantee of quality because learning in a clinical context is more effective and allows for constructive qualification of students. Learning in a clinical simulation context is a strategy to promote simulated clinical experience and assure patient safety. In this work, a learning experience, consisting of simulating a pacemaker implantation, implemented over 3 years with students pursuing the Medical Imaging and Radiotherapy degree at the University of Aveiro was evaluated. Methods: A pacemaker implantation simulation with fluoroscopic support was performed with students (third year) pursuing the Medical Imaging and Radiotherapy degree at the Simulation Centre of our institution over 3 years (2016, 2017–2018), addressing all the simulation phases. An operating theater, video recording system, high-fidelity full-body manikin with remote control and monitoring, anesthesia, and fluoroscopic C-arm imaging equipment were used for the simulation. After the simulation activity, students completed a questionnaire evaluated the importance of this learning experience for their educational process. Results: Overall, the mean score results were consistent, even considering the three independent groups (one for each academic year). Students considered this experience valuable for their education, strongly agreeing that the simulation environment helped their learning process and allowed them to acquire, consolidate, and deepen knowledge. Furthermore, they considered that it impressed on them the necessity to continue to improve their learning, and that they would like to participate in other simulation scenarios. Discussion/Conclusion: This simulation activity was a valuable experience for the learning process of the students because it facilitated the acquisition and consolidation of knowledge. It also allowed the students to be aware of the importance of being engaged in their own education. The results were highly consistent over the 3 years, reinforcing the positive feedback from this experience.

ria.ua.pt | doi | Peer Reviewed

11.  Perceção de estudantes de Matemática sobre a aprendizagem a distância: um caso de estudo no contexto da pandemia COVID-19

Freitas, Adelaide and Neves, António Jorge and Carvalho, Paula

Indagatio Didactica

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

Como consequência da pandemia COVID-19, foram suspensas, em 16 de março de 2020, todas as atividades presenciais nas instituições de ensino em Portugal, obrigando a alterações abruptas nas metodologias de ensino e de aprendizagem. Emergente desta realidade, importa conhecer experiências de ensino e de aprendizagem vivenciadas por professores e estudantes. O presente trabalho foca-se num caso de estudo: um grupo de estudantes universitários inscritos no ano letivo de 2019/2020 na Licenciatura em Matemática de uma Instituição de Ensino Superior (IES) pública. Tem como objetivo analisar a perceção de estudantes de Matemática sobre a sua aprendizagem a distância (online) que lhes foi exigida, com adaptação a novos métodos de ensino a distância, aquisição de novos processos de aprendizagem e hábitos de trabalho, entre outras mudanças, no contexto da primeira vaga da pandemia COVID-19. Para o efeito, foi elaborado um questionário para recolha de informação e, com ele, aplicado um inquérito a todos os estudantes de Matemática inscritos naquela IES. Neste artigo, descrevem-se e analisam-se as respostas dos estudantes que, de forma anónima, participaram no inquérito. Uma análise quantitativa descritiva dessas respostas mostra que, apesar de, na sua maioria, estes estudantes manifestarem preferência por um ensino maioritariamente presencial, também reportam aspetos positivos do ensino a distância, tais como, a interação entre estudantes promovida por atividades em grupo. Não obstante, são refletidos aspetos menos positivos, nomeadamente, ser menos eficaz na esperada interação aluno-professor, assim como na criação de um ambiente favorável à sua participação no processo de aprendizagem.

ria.ua.pt | doi | Peer Reviewed

10.  Clustering genomic words in human DNA using peaks and trends of distributions

Tavares, Ana Helena and Raymaekers, Jakob and Rousseeuw, Peter J. and Brito, Paula and Afreixo, Vera

Advances in Data Analysis and Classification

Springer

In this work we seek clusters of genomic words in human DNA by studying their inter-word lag distributions. Due to the particularly spiked nature of these histograms, a clustering procedure is proposed that first decomposes each distribution into a baseline and a peak distribution. An outlier-robust fitting method is used to estimate the baseline distribution (the ‘trend’), and a sparse vector of detrended data captures the peak structure. A simulation study demonstrates the effectiveness of the clustering procedure in grouping distributions with similar peak behavior and/or baseline features. The procedure is applied to investigate similarities between the distribution patterns of genomic words of lengths 3 and 5 in the human genome. These experiments demonstrate the potential of the new method for identifying words with similar distance patterns.

ria.ua.pt | doi | Peer Reviewed

9.  Does induction of labor at term increase the risk of cesarean section in advanced maternal age? A systematic review and meta-analysis

Fonseca, Maria João and Santos, Fernanda and Afreixo, Vera and Silva, Isabel Santos and Almeida, Maria do Céu

European Journal of Obstetrics & Gynecology and Reproductive Biology

Elsevier

Background: Women of advanced maternal age, defined as >= 35 years at delivery, are at increased risk of multiple complications during pregnancy, with perinatal death being one of the most feared. For instance, the risk of stillbirth at term in this subgroup of women is higher than in younger women, and particularly high beyond 39 weeks of gestation. Induction of labor at 39–40 weeks might help prevent some cases of perinatal death, however, the fact that induction of labor has been historically associated with an increased risk of cesarean delivery and the knowledge that advanced maternal age is an independent risk factor for cesarean delivery are some of the major reasons why clinicians are reluctant to offer elective induction of labor in this particular group. Objective: The aim of the study was to assess if induction of labor in advanced maternal age was associated with increased rates of cesarean delivery when compared to expectant management. Material and methods: We performed an electronic search limited to published articles available between January 2000 and March 2020. Randomized clinical trials and retrospective studies with large cohorts comparing induction of labor with expectant management in singleton pregnancies at term, of women aged >= 35 years were included. The primary outcome was the rate of cesarean delivery in induction of labor versus expectant management, and secondary outcomes were the occurrence of assisted vaginal delivery and postpartum hemorrhage. Results: Eight studies, including 81151 pregnancies (26,631 in the induction group and 54,520 expectantly managed), were included in the analysis. Six of the included studies were randomized clinical trials with the remaining two being observational and retrospective cohort studies. Induction of labor was not associated with a significant increased risk of cesarean delivery (OR 0.97, 95 % CI 0.86–1.1), assisted vaginal delivery (OR 1.12, 95 % CI 0.96–1.32) or postpartum hemorrhage (OR 1.11, 95 % CI 0.88–1.41). Discussion: The belief that induction of labor is associated with an increased risk of cesarean delivery is based on the results of retrospective studies comparing induction with spontaneous labor at the same gestational age. However, at any point in a pregnancy, the comparison should be between induction of labor and expectant management, with the latter contributing to a pregnancy of greater gestation age and not always leading to spontaneous labor. When comparing induction to expectant management, our study shows no significant increase of cesarean section, assisted vaginal delivery or postpartum hemorrhage. Our study was not powered to assess neonatal outcomes, and additional research is needed to confirm whether induction of labor might have a positive effect in preventing stillbirth. Conclusion: Induction of labor at term in advanced maternal age has no significant impact on cesarean delivery rates, assisted vaginal delivery or postpartum hemorrhage, giving additional reassurance to obstetricians who would consider this intervention in this particular subgroup.

ria.ua.pt | doi | Peer Reviewed

8.  Estrogen receptors in urogenital schistosomiasis and bladder cancer: estrogen receptor alpha-mediated cell proliferation

Bernardo, Carina and Santos, Júlio and Costa, Céu and Tavares, Ana and Amaro, Teresina and Marques, Igor and Gouveia, Maria João and Félix, Vítor and Afreixo, Vera and Brindley, Paul J. and Costa, José Manuel and Amado, Francisco and Helguero, Luisa and Santos, Lúcio L.

Urologic Oncology: Seminars and Original Investigations

Elsevier

Estrogen-like metabolites have been identified in S. haematobium, the helminth parasite that causes urogenital schistosomiasis (UGS) and in patients´ blood and urine during UGS. Estrogen receptor (ER) activation is enriched in the luminal molecular subtype bladder cancer (BlaCa). To date, the significance of ER to these diseases remains elusive. We evaluated ERα and ERβ expression in UGS-related BlaCa (n = 27), UGS-related non-malignant lesions (n = 35), and noninfected BlaCa (n = 80). We investigated the potential of ERα to recognize S. haematobium-derived metabolites by docking and molecular dynamics simulations and studied ERα modulation in vitro using 3 BlaCa cell lines, T24, 5637 and HT1376. ERα was expressed in tumor and stromal cells in approximately 20% noninfected cases and in 30% of UGS-related BlaCa, predominantly in the epithelial cells. Overall, ERα expression was associated with features of tumor aggressiveness such as high proliferation and p53 positive expression. ERα expression correlated with presence of schistosome eggs. ERβ was widely expressed in both cohorts but weaker in UGS-related cases. molecular dynamics simulations of the 4 most abundant S. haematobium-derived metabolites revealed that smaller metabolites have comparable affinity for the ERα active state than 17β-estradiol, while the larger metabolites present higher affinity. Our in vitro findings suggested that ERα activation promotes proliferation in ERα expressing BlaCa cells and that this can be reverted with anti-estrogenic therapy. In summary, we report differential ER expression between UGS-related BlaCa and noninfected BlaCa and provide evidence supporting a role of active ERα during UGS and UGS-induced carcinogenesis.

ria.ua.pt | doi | Peer Reviewed

7.  Multivariate and multiscale complexity of long-range correlated cardiovascular and respiratory variability series

Martins, Aurora and Pernice, Riccardo and Amado, Celestino and Rocha, Ana Paula and Silva, Maria Eduarda and Javorka, Michal and Faes, Luca

Entropy

MDPI

Assessing the dynamical complexity of biological time series represents an important topic with potential applications ranging from the characterization of physiological states and pathological conditions to the calculation of diagnostic parameters. In particular, cardiovascular time series exhibit a variability produced by different physiological control mechanisms coupled with each other, which take into account several variables and operate across multiple time scales that result in the coexistence of short term dynamics and long-range correlations. The most widely employed technique to evaluate the dynamical complexity of a time series at different time scales, the so-called multiscale entropy (MSE), has been proven to be unsuitable in the presence of short multivariate time series to be analyzed at long time scales. This work aims at overcoming these issues via the introduction of a new method for the assessment of the multiscale complexity of multivariate time series. The method first exploits vector autoregressive fractionally integrated (VARFI) models to yield a linear parametric representation of vector stochastic processes characterized by short- and long-range correlations. Then, it provides an analytical formulation, within the theory of state-space models, of how the VARFI parameters change when the processes are observed across multiple time scales, which is finally exploited to derive MSE measures relevant to the overall multivariate process or to one constituent scalar process. The proposed approach is applied on cardiovascular and respiratory time series to assess the complexity of the heart period, systolic arterial pressure and respiration variability measured in a group of healthy subjects during conditions of postural and mental stress. Our results document that the proposed methodology can detect physiologically meaningful multiscale patterns of complexity documented previously, but can also capture significant variations in complexity which cannot be observed using standard methods that do not take into account long-range correlations.

ria.ua.pt | doi | Peer Reviewed

6.  Modelling irregularly spaced time series under preferential sampling

Monteiro, Andreia and Menezes, Raquel and Silva, Maria Eduarda

RevStat

Instituto Nacional de Estatística

Irregularly spaced time series are commonly encountered in the analysis of time series. A particular case is that in which the collection procedure over time depends also on the observed values. In such situations, there is stochastic dependence between the process being modeled and the times at which the observations are made. Ignoring this dependence can lead to biased estimates and misleading inferences. In this paper, we introduce the concept of preferential sampling in the temporal dimension and we propose a model to make inference and prediction. The methodology is illustrated using artificial data as well a real data set.

ria.ua.pt | Peer Reviewed

5.  Treatment priorities among older people if faced with serious illness: improving the quality of life or extending life?

Jorge, Rafaela and Freitas, Adelaide and Sousa, Liliana

Journal of Statistics on Health Decision

Universidade de Aveiro; Centro Hospitalar do Baixo Vouga

Objective: This study aimed to analyse older people`s end-of-life care priorities and to identify factors associated with these priorities. Methods: A cross-sectional face-to-face survey with 400 individuals aged ≥60 living in the city of Belo Horizonte, Brazil was conducted. Participants were asked their treatment priorities if faced with a serious illness with limited time to live. Multinomial logistic regressions were used to identify the associated factors. The possible instability of the factors in the final multivariable model were assessed by bootstrap resampling. Results: Most participants (65.3%) chose the option ‘improve quality of life for the time they had left’. Only 4% said extending life was the most important priority while the option ‘both equally important’ (quality and extension) was chosen by 30.8 of respondents. Participants in the age group 60-69 years were more likely to choose both quality and life extension than choose to extend life alone (AOR=0.18, 95% CI:0.05-0.72; ref: 80+ years). The group comprised of single + widowers is more likely to prioritize both quality and extension than to prioritize just extending life (AOR=0.28, 95% CI:0.09- 0.89; ref: the others marital status) and or just improving the quality of life (AOR=0.62, 95% CI:0.40-0.95; ref: the others marital status). Conclusion: The findings indicated that treatment for improving the quality of life was the most important priority. Two factors influenced the priorities (age group and marital status). To meet people's treatment priorities at end of life, policies need to be formulated to develop palliative care services, train health-care professionals, and educate patients

ria.ua.pt | doi | Peer Reviewed

4.  Design of pulmonary rehabilitation programmes during acute exacerbations of COPD: a systematic review and network meta-analysis

Machado, Ana and Matos Silva, Pedro and Afreixo, Vera and Caneiras, Cátia and Burtin, Chris and Marques, Alda

European Respiratory Review

European Respiratory Society

This systematic review aimed to systematise the different designs used to deliver pulmonary rehabilitation during acute exacerbations of COPD (AECOPD) and explore which ones are the most effective. PubMed, Scopus, Web of Science, EBSCO and Cochrane were searched. Randomised controlled trials comparing pulmonary rehabilitation or at least one of its components with usual care or comparing different components of pulmonary rehabilitation were included. Network meta-analysis was conducted in MetaXL 5.3 using a generalised pairwise modelling framework. Pooled effects compared each treatment to usual care. 42 studies were included. Most studies were conducted in an inpatient setting (57%) and started the intervention 24-48 h after hospital admission (24%). Exercise training (71%), education and psychosocial support (57%) and breathing techniques (55%) were the most used components. Studies combining exercise with breathing techniques presented the larger effects on exercise capacity (weighted mean difference (WMD) -41.06, 95% CI -131.70-49.58) and health-related quality of life (WMD 16.07, 95% CI 10.29-21.84), and breathing techniques presented the larger effects on dyspnoea (WMD 1.90, 95% CI 0.53-3.27) and length of hospitalisation (effect size =0.15, 95% CI -0.28-0.57). A few minor adverse events were found.Pulmonary rehabilitation is a safe intervention during AECOPD. Exercise, breathing techniques, and education and psychosocial support seem to be the core components for implementing pulmonary rehabilitation during AECOPD. Studies may now focus on comparisons of optimal timings to start the intervention, total duration of the intervention, duration and frequency of sessions, and intensity for exercise prescription.

ria.ua.pt | doi | Peer Reviewed

Proceedings


3.  World Health Organization Quality of Life-BREF: versão Aphasia-Friendly

Araújo, Ana and Sá-Couto, Pedro and Valente, Paula and Matos, Maria

14.º Congresso Português do AVC

Sociedade Portuguesa do AVC

Sem resumo disponível.

ria.ua.pt | Peer Reviewed

2.  Classification of HRV using Long Short-Term Memory networks

Leite, Argentina and Silva, Maria Eduarda and Rocha, Ana Paula

2020 11th Conference of the European Study Group on Cardiovascular Oscillations (ESGCO)

IEEE

This work focus on detection of diseases from Heart Rate Variability (HRV) series using Long Short-Term Memory (LSTM) networks. First, non-linear models are used to extract sequences of features that characterize the HRV series. These time sequences are then used as input for the LSTM. HRV recordings from the Noltisalis database are used for training and testing this approach. The results indicate that the procedure provides accuracy scores in the range of 86.7% to 90.0% on the test set.

ria.ua.pt | doi | Peer Reviewed

1.  Vector Autoregressive Fractionally Integrated models to assess multiscale complexity in cardiovascular and respiratory time series

Martins, Aurora and Amado, Celestino and Rocha, Ana Paula and Silva, Maria Eduarda and Pernice, Riccardo and Javorka, Michal and Faes, Luca

2020 11th Conference of the European Study Group on Cardiovascular Oscillations (ESGCO)

IEEE

Cardiovascular variability is the result of the activity of several physiological control mechanisms, which involve different variables and operate across multiple time scales encompassing short term dynamics and long range correlations. This study presents a new approach to assess the multiscale complexity of multivariate time series, based on linear parametric models incorporating autoregressive coefficients and fractional integration. The approach extends to the multivariate case recent works introducing a linear parametric representation of multiscale entropy, and is exploited to assess the complexity of cardiovascular and respiratory time series in healthy subjects studied during postural and mental stress.

ria.ua.pt | doi | Peer Reviewed
(latest changes on 2021-09-13 18:40)

© 2019 CIDMA, all rights reserved