Browsing by Issue Date, starting with "2020"
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- Audiovisual Quality of Live Music Streaming over Mobile Networks using MPEG-DASHPublication . Rodrigues, Rafael; Pocta, Peter; Melvin, Hugh; Bernardo, Marco V.; Pereira, Manuela; Pinheiro, Antonio M. G.The MPEG-DASH protocol has been rapidly adopted by most major network content providers and enables clients to make informed decisions in the context of HTTP streaming, based on network and device conditions using the available media representations. A review of the literature on adaptive streaming over mobile shows that most emphasis has been on adapting the video quality whereas this work examines the trade-off between video and audio quality. In particular, subjective tests were undertaken for live music streaming over emulated mobile networks with MPEG-DASH. A group of audio/video sequences was designed to emulate varying bandwidth arising from network congestion, with varying trade-off between audio and video bit rates. Absolute Category Rating was used to evaluate the relative impact of both audio and video quality in the overall Quality of Experience (QoE). One key finding from the statistical analysis of Mean Opinion Scores (MOS) results using Analysis of Variance indicates that providing reduced audio quality has a much lower impact on QoE than reducing video quality at similar total bandwidth situations. This paper also describes an objective model for audiovisual quality estimation that combines the outcomes from audio and video metrics into a joint parametric model. The correlation between predicted and subjective MOS was computed using several outcomes (Pearson and Spearman correlation coefficients, Root Mean Square Error (RMSE) and epsilon-insensitive RMSE). The obtained results indicate that the proposed approach is a viable solution for objective audiovisual quality assessment in the context of live music streaming over mobile network.
- Uma aula diferentePublication . Silveira, PedroEste artigo visa revelar o impacto da introdução de atividades interativas na aula na satisfação dos alunos. Partindo da abordagem construtivista do conhecimento e das vantagens da aprendizagem ativa (active learning), foi realizado um estudo empírico que consistiu na comparação dos questionários de satisfação dos alunos de duas turmas em que não foram utilizadas atividades com outras duas em que estas foram realizadas. Os questionários foram sujeitos à análise de conteúdo qualitativa e quantitativa, revelando a valorização que os alunos atribuem às aulas interativas. A interatividade passou a ser considerada o mais importante ponto forte de avaliação tanto da unidade curricular como do docente. Estes resultados reforçam estudos anteriores que mostram as vantagens da aprendizagem ativa no aumento da satisfação dos alunos. Eles são particularmente importantes na área da Ciência Política, em que um tipo de aprendizagem que estimule as capacidades analíticas, o espírito crítico e as competências comunicacionais será especialmente adequado.
- Explicação CientíficaPublication . Castro, EduardoArtigo opinativo do estado da arte da explicação científica. Análise e discussão de modelos e teorias mais relevantes da literatura contemporânea, designadamente, o modelo dedutivo-nomológico, os modelos indutivo-estatístico e de relevância estatística, a teoria pragmática das questões ‘porquê?’, a teoria unificadora dos argumentos padrão e a teoria causal/não-causal contrafactual.
- Perceived Emotional Intelligence: what is its influence in Subjective Well-Being?Publication . Barbosa, Maria Miguel; Monteiro, Samuel; Pereira, Henrique; Esgalhado, Graça; Afonso, Rosa Marina; Loureiro, ManuelIn this article we propose to explore the Perceived Emotional Intelligence influence in Subjective Well-Being. To do so, we carry out a quantitative, transversal study adopting a descriptive approach and inter-subject correlational design. The sample is formed of n = 1377 Portuguese and Brazilian participants, between 18 and 81 years of age, of whom 57.8% identified themselves as female and 42.1% as male, 44.4% were Portuguese and 54.9% were Brazilian. In terms of education 38,1% had a post-graduate/master, 33,2% had a first degree/diploma, 14.9% had up to 12 years of schooling and 13.8% had a Ph.D./post-Ph.D. Participants answered the Assessing Emotions Scale and the Reduced Version of the Portuguese Scale of Positive and Negative Affect. There are differences in many dimensions of PEI, according to socio-demographic characteristics and high perception of the competences forming EI is associated with SWB and has a great effect on predicting the variance of Positive Affect.
- Anaerobic Threshold Biophysical Characterisation of the Four Swimming TechniquesPublication . Carvalho, Diogo Duarte; Soares, Susana; Zacca, R; Sousa, João; Marinho, Daniel; Silva, António; Vilas Boas, J. Paulo; Fernandes, Ricardo J.The anaerobic threshold (AnT) seems to be not only a physiologic boundary but also a transition after which swimmers technique changes, modifying their biomechanical behaviour. We expanded the AnT concept to a biophysical construct in the four conventional swimming techniques. Seventy-two elite swimmers performed a 5×200 m incremental protocol in their preferred swimming technique (with a 0.05 m·s-1 increase and a 30 s interval between steps). A capillary blood samples were collected from the fingertip and stroke rate (SR) and length (SL) determined for the assessment of [La], SR and SL vs. velocity inflexion points (using the interception of a pair of linear and exponential regression curves). The [La] values at the AnT were 3.3±1.0, 3.9±1.1, 2.9±1 .34 and 4.5±1.4 mmol·l-1 (mean±SD) for front crawl, backstroke, breaststroke and butterfly, and its corresponding velocity correlated highly with those at SR and SL inflection points (r=0.91-0.99, p<0.001). The agreement analyses confirmed that AnT represents a biophysical boundary in the four competitive swimming techniques and can be determined individually using [La] and/or SR/SL. Blood lactate increase speed can help characterise swimmers' anaerobic behaviour after AnT and between competitive swimming techniques.
- Energy Sustainability Universal Index (ESUI): A proposed framework applied to the decision-making evaluation in power system generationPublication . Silva, Ricardo M.; Silva, Ana R.C.; Lima, Tânia M.; Santos, Fernando Charrua; Osório, Gerardo J.There are numerous methodologies to measure sustainability, but there are few models on Energy Sustainability (ES) that focus on the proper use of energy sources. This manuscript aims to present the ESUI (Energy Sustainability Universal Index) framework for power generation. The method development consisted of four stages: (i) A survey of the State-of-the-Art to choose the dimensions and variables; (ii) The definition of “damage” concept to incorporate subjective values; (iii) Validation of the found variables through the analysis of 34 electric power plants randomly chosen and tested; and (iv) The mathematical model. From the analyzed power plants through the proposed model, as an example, the Itaipu Binacional Hydroelectric Power Plant is 42% sustainable with an emphasis in the Political- Territorial dimension, while Trillo Nuclear Power Plant is not economically sustainable. The main contributions of the proposed ESUI framework are the classification and evaluation of ES in five dimensions (Environmental, Economic, Social-Cultural, Political-Territorial, and Technological) through a simple process, helping in the management of the decision-making process, accounting simultaneously for subjective aspects and incorporating weighting factors according to the user’s expert opinion.
- Intranasal fosphenytoin: the promise of phosphate esters in nose-to-brain delivery of poorly soluble drugsPublication . Santos, Adriana O.; Pires, Patrícia C.; Rodrigues, Márcio; Alves, Gilberto; Santos, Liliana T.Intranasal administration could increase both safety and efficacy of drugs acting on the central nervous system, but low solubility severely limits administration through this route. Phenytoin’s prodrug, fosphenytoin, is hydrophilic and freely soluble in water, but less permeable since it is dianionic. We aimed to assess whether this phosphoester prodrug could be a suitable alternative to phenytoin in intranasal delivery. Secondly, we aimed to compare simple formulation strategies in fosphenytoin delivery. Fosphenytoin formulations containing thermosensitive and/or mucoadhesive (hydroxypropyl methylcellulose, HPMC) polymers were developed, guided by viscosity, gelling temperatures, osmolality, and in vitro drug release tests. Then, a pharmacokinetic study was performed, comparing an intravenous fosphenytoin solution, an intranasal fosphenytoin solution, and intranasal fosphenytoin mucoadhesive formulations with or without albumin. Formulations containing HPMC allowed high drug strengths, and had a relatively fast release profile, which was not changed by albumin. Intranasal administration of a formulation with HPMC and albumin prolonged drug concentration over time and led to complete or even increased absolute bioavailability. Moreover, phenytoin’s blood levels did not reach the high peak obtained with intravenous administration. In conclusion, the use of phosphate ester prodrugs could be an efficient and safe strategy to increase the intranasal bioavailability of poorly soluble drugs.
- Governo e elites governativas em Portugal (1976-2020)Publication . Camerlo, Marcelo; Paris, André; Ruel, Teresa; Silva, Patrícia; Silveira, PedroNeste Policy Brief apresentamos alguns dados recentemente recolhidos e analisados no âmbito deste projeto para o caso português. Quanto à estrutura, depois de uma secção de enquadramento sobre o lugar do governo no sistema político português, apresentamos uma breve caracterização do actual governo que servirá como ponto de partida para, nas secções seguintes, analisarmos os atributos básicos do governo e das elites governativas em Portugal desde 1976. Assim, serão analisados os principais atributos dos vários governos constitucionais, o seu desenho organizacional, assim como algumas das características mais importantes dos ministros e dos secretários e subsecretários de Estado. Por fim, mesmo tratando-se de uma arena com especificidades próprias, inclui-se uma secção sobre os governos regionais das regiões autónomas.
- Bark residues valorization potential regarding antioxidant and antimicrobial extractsPublication . Neiva, Duarte; Luís, Ângelo; Gominho, Jorge; Domingues, Fernanda C.; Duarte, Ana Paula; Pereira, HelenaBark residual side streams from industries (Eucalyptus globulus—Eg and Picea abies—Pa) or from control of invasive species in Mediterranean countries (Acacia melanoxylon—Am and Acacia dealbata—Ad) are burned for energy production, although their high content of extractable compounds points to a possible valorization as sources of phytochemicals with antioxidant and antimicrobial activities. Non-polar and polar extracts were obtained, and their phenolic contents, antioxidant activity, antiquorum sensing and antimicrobial potential against several human pathogenic microbes (nine bacteria and two yeasts) were determined. Extraction yield ranged from 0.5 to 37% of barks dry weight varying with species and solvent used, and both water and ethanol extracts presented strong or very strong scavenging antioxidant ability. Eg and Pa non-polar extracts showed the lowest minimum inhibitory concentration for gram-positive bacteria (0.04–1.25 mg/mL), while Ad presented the best results among polar extracts regarding bacteria (0.16 mg/mL for K. pneumoniae) and yeast strains (0.02–0.04 mg/mL). Non-polar extracts showed great response against both Candida species (MIC=0.04–0.63 mg/mL). Each extract had diferent antimicrobial activity showing that species and solvents can be used to tailor compounds to target specifc pathogens. Information regarding these bioactive extracts from residual forest side streams can provide possible utilization routes for natural compounds recovery prior to combustion.
- Severity of Ascites Is Associated with Increased Mortality in Patients with Cirrhosis Secondary to Biliary AtresiaPublication . Guedes, Renata R.; Kieling, Carlos; Santos, Jorge Luiz dos; Rocha, Carolina da; Schwengber, Fernando; Adami, Marina R.; Chedid, Marcio F.; Vieira, Sandra M. G.Background Very few prior studies have investigated the presence of ascites as a prognostic factor in children with cirrhosis. To the best of our knowledge, there are no prior studies evaluating the relationship between severity of ascites and patient survival in children with biliary atresia and cirrhosis. Aims To evaluate the association between severity of ascites and survival of children with cirrhosis and biliary atresia. Methods All children with cirrhosis secondary to biliary atresia evaluated at our institution from 2000 to 2014 were included in this study. Patients were classified into four groups: NA = no ascites; A1 = grade 1 ascites; A2 = grade 2 ascites; and A3 = grade 3 ascites. The primary endpoint of the study was mortality within the first year after patient inclusion. Ninetyday mortality was also evaluated. Prognostic factors related to both endpoints also were studied. [...]