Browsing by Issue Date, starting with "2025-02"
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- Uma Introdução à Filosofia da MatemáticaPublication . Castro, Eduardo Jorge de SousaEste livro é um manual para um primeiro curso de Filosofia da Matemática. Pode ser usado ao nível de uma graduação ou de uma pós -graduação, de Filosofia ou de Matemática. Restantes académicos e investigadores, bem como professores do ensino não -universitário, podem também encontrar aqui uma referência e uma orientação para o seu trabalho e investigação. O livro apenas pressupõe conhecimentos de matemática e de filosofia, de nível pré -universitário.
- Analysis of the influence of the tip clearance on the performance of transonic compressorsPublication . Lopes, Diogo Marques; Brojo, Francisco Miguel Ribeiro ProençaIn aviation, compressor efficiency is essential for reducing operating costs and improving engine performance. More efficient compressors consume less fuel, which reduces airlines' expenses. It is with this goal in mind that this study was carried out, focusing on the analysis of a transonic compressor. This study explores the performance of the NASA Rotor 67 axial compressor in two configurations: with and without tip clearance. Computational fluid dynamics simulations were carried out to evaluate the effects of tip clearance on the flow characteristics and overall efficiency of the compressor. Tip clearance refers to the small gap between the blade tips of a rotor and the surrounding casing in turbomachinery. This gap is necessary and intentionally designed to allow for thermal expansion, mechanical tolerances, and structural deformation during operation to ensure that the blades do not come into direct contact with the casing. In this study, Ansys CFX software was used as a tool to analyze the aerodynamic performance of the transonic compressor under steady-state conditions, and the model used for the simulations was the SST k-? turbulence model. Ansys CFX makes it possible to accurately simulate the complex flow phenomena present in turbomachinery, including the effects of compressibility. The analysis focused on critical performance metrics such as pressure ratio and efficiency, comparing the two models to understand the impact of the gap on flow characteristics. Contours of the relative Mach number and pressure distributions were used to study the flow behavior in different sections of the rotor, highlighting the main differences between the two cases. The results showed that the absence of spacing improves performance, achieving higher pressure ratios and more uniform flow patterns near the blade tips, where the irregularities induced by spacing were mitigated. This was expected, as tip clearance is associated with leaked losses, which can reduce overall efficiency.
- New delivery systems based on gellan gum nanoparticles for Parkinson Diseases TherapeuticsPublication . Rodrigues, Madalena Filipa Geada; Passarinha, Luís António Paulino; Sousa, Ângela Maria Almeida de; Cristóvão, Ana Clara BrazGlobally, there are up to 10 million people diagnosed with Parkinson's Disease, a chronic neurodegenerative disorder without a cure. Physiologically, it is characterized by the progressive loss of dopaminergic neurons in the substantia nigra. Clinically, patients with this disease reveal several motor symptoms, such as tremors, tension, and postural instability, and non-motors, such as depression and anxiety. To date, the most effective drug combination used in the treatment of Parkinson's disease is the administration of levodopa (L-Dopa) combined with catechol-O-methyltransferase (COMT) inhibitors and monoamine oxidase inhibitors to restore dopaminergic brain levels. However, the commercially available inhibitors have low capabilities to cross the blood-brain barrier and, thus, low bioavailability in the brain. Also, the prolonged use of these drugs is associated with high hepatotoxicity, which currently limits their use. Therefore, the discovery of molecules with the potential to inhibit the COMT and the development of new delivery systems for these drugs are crucial elements to improve the effectiveness of existing therapies. Using polymeric nanoparticles as antiparkinsonian drug carriers presents numerous advantages considering the current therapies. These nanosystems can cross biological barriers due to their chemical properties and small size. Furthermore, they can achieve the therapeutic target more efficiently, increasing the bioavailability of the drug in restricted environments, such as the brain. Also, the application of polysaccharides in developing this type of delivery system presents advantages such as lower economic costs and better biocompatibility and biodegradability compared to oral and intravenous therapies. The discovery of the molecules 3,4-dihydroxy-5-nitrobenzonitrile (ZINC035) and 2- bromo-3,4-dihydroxy-S-nitrobenzaldehyde (ZINC496) as new COMT inhibitors, combined with the potential of nanoparticles based on natural polymers, such as gellan and chitosan, as drug delivery systems, have proven to be the impulse for this work. In the first part of this work, an analytical method using High-Performance Liquid Chromatography (HPLC) was developed to detect and quantify these new inhibitors in brain tissue samples from adult Wistar rats. In this study, the biological samples were spiked with each inhibitor and, subsequently, analyzed using two different types of detection, in which electrochemical detection (HPLC-ECD) was more effective for biological matrices than diode-array detection (HPLC-DAD). Additionally, a study was realized using different mobile phases, varying from 9 to 18% (v/v) of the organic compound (acetonitrile) to optimize the experimental procedure time. The results obtained using an HPLC-ECD analysis system interestingly showed that the molecules under study have interaction capabilities with brain tissues, and due to their similarity with commercial inhibitors, their potential use in Parkinson's therapies has been proven. In the progress of this work, a new polymeric delivery system has been developed to improve metabolism and absorption, increasing their chemical stability, decreasing their susceptibility to enzymatic degradation, and improving bioavailability of the commercial drugs. This delivery system results from the complexation of two natural polymers with opposite charges, the gellan gum (GG) and the chitosan (CH). These polymeric complexes were formulated, testing different conditions, varying the molecular weight of chitosan (5 kDa and low molecular weight) and the ratio and concentration of the polymers (0.05-1 mg/mL). After optimization, the GG/CH systems were prepared with the inclusion of the selected COMT inhibitor (ZINC035) or L-Dopa. In order to obtain the encapsulation efficiency of the nanoparticles, a purification system was developed, testing three different methodologies (centrifugation, filtration and molecular exclusion chromatography) and varying some conditions, such as centrifugation speeds (8000- 12500 rpm), the size of filter pore (0.22 and 0.45 µm) and the elution buffers (sodium acetate, sodium chloride and phosphate-buffered saline). The best GG/CH delivery system had a size of 238.52 nm; a polydispersity index (PDI) value of 0.449 and a zeta potential (ZP) of +30.2 mV. Also, GG/CH nanoparticles loaded with ZINC035 showed a mean size of 163.5 nm; a PDI of 0.355; a zeta potential of +20.6 mV and an encapsulation efficiency of 67.04%, which are stable up to 48h after formulation. Finally, the L-Dopa-loaded delivery systems achieved a size of 177.01 nm, a PDI of 0.392, and an encapsulation efficiency of approximately 26%. Overall, the HPLC system with electrochemical detection developed in this work is an effective and innovative methodology for studying COMT inhibitors in biological tissues. Furthermore, nanoparticulate polymeric systems have unique properties that can be used according to the desired intranasal delivery application and will certainly present advantages over conventional therapies.
- Characterization of Elite Rink Hockey Players, Match and Training DemandsPublication . Ferraz, António Leopoldo Lopes; Travassos, Bruno Filipe Rama; Santos, João Alberto Valente dos; Mendes, Pedro Alexandre DuarteThis work aimed to provide valuable insights into the characteristics of players, training, and game demands in rink hockey, applying the knowledge developed towards a more suitable method for monitoring training and competition to enhance player performance. To achieve this, six studies were conducted with specific objectives: (1) to understand the evolutionary trends in the characterization of players and game performance in men's rink hockey; (2) to characterize the body composition and grip strength of elite male rink hockey players and establish the relationship between ethnicity in body composition and grip strength; (3) to understand the applicability of monitoring systems for physical performance analysis in team sports over the last decade in order to develop knowledge for load monitoring in rink hockey; (4) to understand the dynamics of external and internal load throughout the 2-week training period and competition week of a rink hockey International Championship; (5) to propose a new approach to characterize and classify the physiological and biomechanical specificity of training tasks in relation to elite competition - a quadrant-based classification system; (6) to apply the quadrant-based classification system to characterize and classify load demands, considering the physiological and biomechanical requirements of training and games according to positional dimensions. Overall, the results obtained in the six studies of this thesis promoted a proposal for practical applicability from player profiling to training and game monitoring. Study 1 revealed that the literature on rink hockey is scarce and generally presents a holistic approach to physiological and functional demands, cardiorespiratory adaptations, training characteristics, anthropometry, body composition, conditional profile, game characterization, and injuries in rink hockey. However, most studies are conducted on young athletes, with few studies on elite athletes. Thus, it was essential to conduct research toward characterizing elite athletes and the physical demands of training and competition. Study 2 described that given the characteristics of the sport and its neuromuscular adaptation, elite rink hockey players show a specific anthropometric profile considering percentile values of fat and characteristic grip strength for this sport, with ethnicity, right thigh circumference, and right calf circumference being the variables that best describe fat percentile, while age, distal circumference of the right thigh, and ethnicity better describe grip strength. Considering that monitoring through positional analysis technology in rink hockey is almost non-existent, Study 3 sought to understand how research using indoor positioning systems could contribute to a better understanding of the demands of rink hockey. It was found that most studies have focused on performance analysis, load management, injury development process, and nutrition. Still, in Study 3, it was proposed that integrated analysis of kinematic and mechanical variables should be studied alongside their correlation or association with internal load variables to understand athletes' performance improvement strategies better. In this logic, Study 4 observed in a preparation for an international competition that training demands do not match those of the competition. High-intensity impacts followed by decelerations characterize the metrics that most impact athletes' subjective perception of effort during competition, which are underexplored during training, particularly high-intensity impacts. Therefore, in Studies 5 and 6, a proposal was developed to characterize physiological and biomechanical demands in training and competition situations, providing coaching staff with a methodological tool to optimize microcycle planning. In Study 5, it was found that no exercise category analysed has the physiological and biomechanical demands of the game. While the game is characterized by high physiological and biomechanical demands, most exercises have low physiological and biomechanical demands, except for exercises performed in midcourt and full court, which have high physiological and medium biomechanical demands. Still, in Study 5, no category of exercises with simultaneous high biomechanical and low physiological demands was found. Finally, in study 6, a misalignment between the specific demands of different positions was observed when comparing the game with the training sessions of the microcycle. That is, although the game is characterized by high physiological and biomechanical efforts, advanced players tend to achieve a lower physiological and biomechanical profile than defender-midfielder players. These differences are not considered throughout the microcycle. Finally, this approach used in Studies 5 and 6 allows us to assume that the integrated variables that best characterize the physiological demands in rink hockey are average heart rate, maximum heart rate, and distances skated at high intensity. In turn, those that best integrate biomechanical demands are high-intensity impacts, decelerations, and accelerations. In summary, the results suggest that training does not meet the demands of the game, compromising athletes' appropriate response capacity, particularly considering the game's biomechanical demands. This is because there is a failure to replicate these demands in training in terms of training structure and player individualization, mainly due to the absence of exercises that promote high-intensity impacts associated with decelerations and accelerations. The quadrant-based classification system proposal presented in studies 5 and 6 offers coaching staff a methodology to analyse and adjust training structure and player specificity, thus promoting an environment that better replicates competition demands.
- Bug Taxonomy Classification Using Machine Learning AlgorithmsPublication . Caldeira, Beatriz Isabel Trocas; Pombo, Nuno Gonçalo Coelho CostaBugs are a natural occurrence in the realm of software development. As society increasingly relies on software, the frequency of these occurrences has naturally increased as well, potentially leading to catastrophic consequences for products or businesses. To monitor and manage the bug resolution process, various bug tracking systems have been developed. These platforms enable teams responsible for bug analysis to view identified bugs, track the most common issues, and monitor their resolution status. However, the challenge lies in analyzing each of these reports. In large-scale products, hundreds of reports can be submitted daily through these platforms, whether by other developers, pen testers, or end users. End users, due to their likely lack of knowledge about software, system architecture, or other inherent processes, may submit incorrect or unclear reports. Addressing the need for developers to manually analyze and classify each of these reports (a complex and time-consuming task) through automation is an idea that has been explored by various researchers. This research aims to develop a comprehensive and detailed classification schema that can provide additional, automated information to report analysts, thereby facilitating part of their analysis process. To achieve this, the proposed solution is based on leveraging the high performance and capabilities of the BERT model, a model rooted on Transformer architecture, to classify these reports as accurately as possible, based on the textual descriptions within each report. A dataset was created following this schema, designed through a divideand-conquer approach, and multiple models were trained on each category. The results indicate that BERT can form the basis of a robust solution for this purpose, even when provided with a small amount of labeled data as input and despite the need for some refinement in the training process. The best results were obtained when both the title and the description were used together as input data for the model, with one model achieving an overall accuracy of 75%, and the lowest accuracy being 54.6%.
- Deep Learning-Based Software Defect Prediction via Semantic Key Features of Source Code, Handling Imbalanced DatasetsPublication . Andrade, Hiro Gaspar Inglês de; Pombo, Nuno Gonçalo Coelho Costa; Pais, Sebastião Augusto Rodrigues FigueiredoThis work is part of the master’s thesis in Computer Engineering at the University of Beira Interior. It addresses themes related to software defect prediction, known as SDP, with the main objective of developing a predictive model using contextual features generated through deep learning models. To achieve the defined goals, five fundamental steps were followed: data preprocessing, mapping and embedding of tokens, extraction of contextual information, handling of datasets with class imbalance, and building the machine learning model for defect prediction. The dataset used was PROMISE, which encompasses software projects developed in Java, with multiple versions for each one. The experiments were conducted individually for each version, using static and contextual features generated through LSTM networks. The models were evaluated based on AUC, Accuracy, MCC, Recall, and Precision metrics. In general, it was observed that the use of contextual features resulted in significantly better performance. Among the models tested, Logistic Regression proved to be the most effective, demonstrating the best predictive capability. However, when combining different versions of the projects, a drop in performance was recorded, with the MCC showing low values, especially in the case of Naive Bayes, which in some scenarios even presented negative values. This phenomenon can be explained by factors such as concept drift (the change in data behavior over time) and overfitting (when the model fits excessively to the training data, compromising its ability to generalize), issues that have not been deeply addressed but are considered for future work.
- Análise de ganhos em saúde de prematuros alimentados com recurso ao banco de leite humano: Revisão sistemática da literaturaPublication . Gonçalves, Nuno Miguel Barreto; Almeida, Anabela Antunes de; Pinto, Paula Cristina SantosEsta revisão sistemática teve como objetivo identificar os benefícios para a saúde dos recém-nascidos pré-termo alimentados com leite humano proveniente de um banco de doações. Foram analisados dezasseis estudos recentes envolvendo diferentes populações e unidades neonatais. Os resultados indicaram que o leite humano doado está associado a uma redução significativa da incidência de doenças graves, como a enterocolite necrosante, a sépsis de início tardio e outras complicações neonatais. Além disso, demonstrou ser eficaz no apoio ao crescimento de bebés prematuros, especialmente quando utilizado com fortificantes adequados, e na promoção de uma microbiota intestinal saudável, que contribui para o desenvolvimento do sistema imunitário. Vários estudos demonstraram que os recém-nascidos alimentados com leite humano doado têm uma menor incidência de enterocolite necrosante em comparação com os alimentados exclusivamente com fórmula. Em algumas unidades neonatais, a implementação de bancos de leite humano contribuiu para uma redução da sépsis e da retinopatia da prematuridade. No que diz respeito ao crescimento, observou-se que a utilização de leite humano doado, devidamente fortificado, não compromete o desenvolvimento ponderal dos bebés prematuros, o que reforça a sua eficácia nos regimes nutricionais. Conclui-se que o leite humano doado é uma intervenção eficaz e segura para a promoção da saúde de recém-nascidos prematuros, com impacto positivo na redução da morbimortalidade neonatal. A implementação de bancos de leite humano e de políticas que incentivem a doação são fundamentais para garantir o acesso a esse recurso nas unidades de terapia intensiva, principalmente na ausência ou insuficiência de leite materno. A prática do uso de leite humano doado deve ser incentivada como parte essencial dos cuidados neonatais em ambientes clínicos.
- Exploring the Basis of the Therapeutic Potential of Sulphurous Thermal Waters in Allergic Rhinitis: A Comprehensive Study in an ex-vivo 3D Model of Nasal Epithelial IntegrityPublication . Bonneau, Lucile; Barata, Luis Manuel Taborda; Cardoso, ElsaAllergic rhinitis is a chronic inflammatory condition of the nasal mucosa that impairs epithelial integrity and significantly impacts quality of life. While conventional treatments alleviate symptoms, their limitations have spurred interest in complementary therapies such as the nebulization of sulphurous thermal waters, which are rich in H2S. Despite reported anti-inflammatory properties, the effects of sulphurous thermal waters in allergic rhinitis remain unclear. This study evaluated the therapeutic potential of sulphurous thermal waters in an ex vivo three-dimensional nasal epithelial model (MucilAirTM) derived from patients with allergic rhinitis. The effects of sulphurous thermal water nebulization on epithelial barrier integrity and pro-inflammatory cytokine secretion were analysed under acute and chronic inflammation induced by LPS and TNF-a. Key assessments included TEER, cytokine quantification (IL-8 and MCP-1), and histological evaluation. The results demonstrated that neither sulphurous thermal waters nor isotonic saline solution nebulization, nor H2S supplementation, produced significant anti-inflammatory effects. TEER analysis indicated that epithelial integrity was compromised by inflammation, with no improvement from treatments. Levels of IL-8 and MCP-1 increased with inflammation but were not reduced by sulphurous thermal waters, saline solution, or H2S treatment. Histological evaluation further confirmed that sulphurous thermal waters offered no additional benefit compared to saline in reducing mucus production or goblet cell hyperplasia. These findings highlight the need for future studies to explore thermal waters with higher H2S concentrations (<0.1 mg/L in this study), alternative inflammatory triggers, and more complex models incorporating immune cells to better replicate the pathophysiology of allergic rhinitis.
- Análise de Soluções e Processos de Segurança de Informação em Contexto Institucional no Ensino SuperiorPublication . Manteigueiro, Miguel Filipe da Paula; Gomes, Paulo Alexandre de Jesus; Inácio, Pedro Ricardo MoraisA cibersegurança é um campo cada vez mais emergente no nosso mundo interligado. Com o crescimento exponencial do volume de informações pessoais e profissionais a circular pelas redes digitais, a segurança e a proteção de dados tornam-se cruciais para garantir a privacidade, a integridade e a disponibilidade desses dados. Neste contexto, a proteção contra acessos não autorizados, o combate a ataques cibernéticos e a prevenção de perdas de informação são desafios constantes que requerem soluções sofisticadas e atualizadas. A cibersegurança envolve uma série de práticas e tecnologias desenhadas para salvaguardar sistemas, redes e programas de ciberataques que visam explorar falhas e vulnerabilidades para fins maliciosos. Assim, a segurança de dados não é apenas uma preocupação para quaisquer organizações ou instituições, mas também para o cidadão comum, que se vê ameaçado por riscos como o roubo de identidade, fraude e a invasão da sua privacidade online. O presente estágio foi desenvolvido nos Serviços de Informática da Universidade da Beira Interior (SI.UBI), tendo como objetivo a análise de soluções e processos de segurança da informação em contexto institucional no ensino superior. Desta forma, é feito um enquadramento teórico-prático das várias soluções existentes ao nível da cifragem de bases de dados, ferramentas e desafios relativos à realização de auditorias de segurança, elaboração e definição de um plano de segurança da informação e para a elaboração de uma política de controlo de acessos para documentos internos à instituição. Na sua essência, este trabalho permitiu definir um conjunto de medidas e procedimentos no campo da cibersegurança, conformidade, proteção e segurança de dados numa instituição de ensino superior público. Nomeadamente, demonstrou a viabilidade da utilização do Transparent Data Encryption, um mecanismo presente no Microsoft SQL Server para a cifragem de bases de dados, com um impacto mínimo no desempenho do Sistema de Gestão de Bases de Dados. A auditoria de segurança elaborada revelou diversas vulnerabilidades, cujo impacto pode ser severo, sendo necessário implementar ações de melhoria com a máxima brevidade. Por outro lado, a criação de um plano de segurança da informação e a elaboração de uma política de controlo de acessos aos documentos internos da Universidade da Beira Interior, apresentam as bases para uma possível implementação de um sistema de gestão documental e o comprometimento contínuo para assegurar a segurança da informação na instituição.
- The Impact of Electrification in Automotive Design for Light VehiclesPublication . Calhamar, António Maria Sancho Mègre Queimado; Monteiro, João Manuel Milheiro Caldas PaivaThis dissertation aims to explore the impact of electrification in automotive design. Pivotal historic events that helped shape the contemporary automobile are crucial, as they not only offer a view into varying trends across automotive history but also show how the electric vehicle was once the dominant choice through market share in the early 1900s. This subject matter also elicits interest on the importance of manufacturers, brands and how they adapt to innovations, trends, legislation and consumer interest. The presentation of a case study comparison between electric and internal combustion powered vehicle granted a framework to observe the contrast between two means of propulsion, and what they entail. Subsequently, challenges and opportunities in regard to electric propulsion were researched and analysed. The conclusion being that weight, price, energy density, inadequate infrastructure and lack of versatility as a result of time-consuming charging still plague the electric vehicle, however, home renewable energy, ease of use, solid state batteries, superior packaging, smaller drivetrain volume, absence of mechanical connections between components, lower maintenance needs and running costs, higher efficiency, lower center of gravity, and increased interior space all provide opportunities for electric vehicles to affirm themselves in the highly competitive automotive sector.