Browsing by Issue Date, starting with "2021-08"
Now showing 1 - 10 of 15
Results Per Page
Sort Options
- Funcionalidades e affordances como bases para classificação de apps jornalísticas destinadas a smartphonesPublication . Canavilhas, João; Empinotti, MarinaA centralidade adquirida pelos telefones celulares no cotidiano global transformou estes dispositivos em objetos de interesse para diversas áreas, entre as quais o jornalismo. A evolução tecnológica destes aparelhos, com o constante surgimento de novas valências, alterou as rotinas de produção jornalística, mas também as formas de relacionamento entre o jornalismo e o seu público. Por isso, atualmente é impossível falar de jornalismo sem referir o papel dos celulares em alguma das suas fases de produção, circulação e consumo. [...]
- Plunging Airfoil: Reynolds Number and Angle of Attack EffectsPublication . Camacho, E. A. R.; Neves, Fernando M. S. P.; Silva, André; Barata, Jorge M. M.Natural flight has consistently been the wellspring of many creative minds, yet recreating the propulsive systems of natural flyers is quite hard and challenging. Regarding propulsive systems design, biomimetics offers a wide variety of solutions that can be applied at low Reynolds numbers, achieving high performance and maneuverability systems. The main goal of the current work is to computationally investigate the thrust-power intricacies while operating at different Reynolds numbers, reduced frequencies, nondimensional amplitudes, and mean angles of attack of the oscillatory motion of a NACA0012 airfoil. Simulations are performed utilizing a RANS (Reynolds Averaged Navier-Stokes) approach for a Reynolds number between 8.5×10^3 and 3.4×10^4, reduced frequencies within 1 and 5, and Strouhal numbers from 0.1 to 0.4. The influence of the mean angle-of-attack is also studied in the range of 0º to 10º. The outcomes show ideal operational conditions for the diverse Reynolds numbers, and results regarding thrust-power correlations and the influence of the mean angle-of-attack on the aerodynamic coefficients and the propulsive efficiency are widely explored.
- Cross-border cooperation to strengthen innovation and knowledge transfer: An Iberian casePublication . Nave, Edgar; Franco, MárioThis study seeks to find out the main achievements of a cross-border cooperation project (INESPO III) in terms of innovation and university-firm knowledge transfer in a region situated in the central region of Portugal and Castile and León, Spain. To achieve this aim, research of a qualitative and exploratory nature was chosen., that is, case study method. Data collection was based on seven interviews with several project actors, and content analysis was also used. Through interviews with project beneficiaries, empirical evidence suggests that this type of cooperation allows access to new sources of external knowledge, with the network benefiting globally from each partner’s type of specialization. This study makes an important contribution to the literature on cross-border cooperation by extending its field of research to knowledge transfer and innovation, analysing a project that has produced good results. It can be determinant for government institutions responsible for administering cross-border incentive systems, and for partner networks in drawing process of similar projects for benefit of their own regions, besides the clear academic interest in business cooperation networks. Final results and main contributions of the project are also presented.
- Hypothetical Apophis deep ocean impact - Energy analysisPublication . Morais, Renato; Santos, Luís; Silva, André; Melício, RuiThis paper models a hypothetical Apophis asteroid impact on an chosen deep ocean point on the globe. To assess the potential vulnerabilities of an exposed coast population, the impact effects were assessed as a function of the distance to the asteroid's impact point as well as altitude for the tsunami case. All the tools and models used are valid and can be implemented for any other point on the Earth's surface. The impact modelling includes the analysis of cratering formation, generated earthquake, overpressure, ejected material, generated thermal radiation and tsunami, as well as the global geophysical effects of the impact. The vulnerability models entail best, expected, and worst case scenarios, which allows a reasonable range of results. As the impact occurs in the ocean, and if its a great distance away from populated areas, the population is safeguarded from most of the impact effects. The tsunami is undoubtedly the most far-reaching and threatening impact effect from an asteroid impact on the ocean.
- Hawking Radiation and Black Hole Gravitational Back Reaction - A Quantum Geometrodynamical Simplified ModelPublication . Marto, JoãoThe purpose of this paper is to analyse the back reaction problem, between Hawking radiation and the black hole, in a simplified model for the black hole evaporation in the quantum geometrodynamics context. The idea is to transcribe the most important characteristics of the Wheeler-DeWitt equation into a Schrödinger’s type of equation. Subsequently, we consider Hawking radiation and black hole quantum states evolution under the influence of a potential that includes back reaction. Finally, entropy is estimated as a measure of the entanglement between the black hole and Hawking radiation states in this model.
- The Influence of Embeddedness on Entrepreneurship, Innovation and Strategy: A Gender Perspective in the Agri-Food SectorPublication . Santos, Gina; Marques, C.S.E.; Ferreira, João José de MatosThis study aims to identify the antecedents of entrepreneurial activity in the agri-food sector of the Portuguese region of Trás-os-Montes and Alto Douro (TMAD), taking into account a gender perspective. Thus, we intend to assess whether the environment influences embeddedness, and whether embeddedness, individual entrepreneurial orientation, innovative behaviour and gender impact or influence the perceptions of feasibility and desirability as antecedents of entrepreneurial activity of entrepreneurs in the agri-food sector of the TMAD region. The measurement instrument was applied to 249 firms in the agri-food sector, created in the last 5 years. A model was conceptualised where the relationships between the constructs relating to embeddedness, IEO and EI were presented, and three control variables were subsequently added: the innovative behaviour, the environment and gender. Univariate and multivariate statistical techniques, such as structural equation modelling, were used to assess the proposed conceptual model. Thus, considering the complexity of the model under study, we performed an analysis which considered personal factors or characteristics, such as innovative behaviour, gender and IEO, as these are characteristics of the individual and may be influenced or shaped by external factors such as the context, i.e., the environment and embeddedness.
- Mitoxantrone-loaded lipid nanoparticles for breast cancer therapy – quality-by-design approach and efficacy assessment in 2D and 3D in vitro cancer modelsPublication . Granja, Andreia; Sousa, Rita Lima; Alves, Cátia; Diogo, Duarte de Melo; Pinheiro, Marina; Sousa, Célia T.; Correia, I.J.; Reis, SaletteBreast cancer is the leading cause of cancer-related deaths among women worldwide. The conventional chemotherapeutic regimens used in the treatment of this disease often lead to severe side-effects and reduced efficacy. In this study, a novel drug delivery system for the chemotherapeutic drug mitoxantrone (Mito) was developed using solid lipid nanoparticles (SLN). The production of the SLN was carried out using an organic-solvent-free, low-cost method and optimized using a Box-Behnken design. SLN presented adequate size for cancer-related applications, more than 90% of EE% and remained stable for at least 6 months. A much higher drug release was obtained at acidic pH (mimicking the endosomal compartment) than plasmatic pH, highlighting the potential of the nanosystem for tumor drug delivery. Additionally, SLN were non-hemolytic and cytocompatible, even at high concentrations of lipid. A significantly higher anti-cancer efficacy was obtained for Mito-loaded SLN comparing to the free drug at different concentrations in MCF-7 2D models. Finally, the nanoformulation was evaluated in heterotypic breast cancer spheroids showing capacity to penetrate the tridimensional structure and ability to induce a high anti-tumoral effect, similarly to the free drug. Overall, these results support that the developed SLN are effective Mito nanocarriers for the treatment of breast cancer.
- Georreferenciação de acidente vascular cerebral isquémico na Cova da Beira (2015-17)Publication . Fernandes, José Luís Pinto; Sousa, Miguel Castelo Branco Craveiro de; Almeida, Pedro Gabriel de Faria Lapa Barbosa deA incidência e mortalidade por acidente vascular cerebral apresentam uma dispersão geográfica díspar, com a existência de hot spots ou stroke belts, isto é regiões com agregados de maior incidência e/ou mortalidade por acidente vascular cerebral, frequentemente associados a condições socioeconómicas desfavoráveis ou a diferenças entre populações urbanas e rurais, por todo o mundo. O presente estudo tem como objectivo estudar a dispersão geográfica de acidente vascular cerebral isquémico na Cova da Beira, de modo a determinar a existência ou ausência de hot spots e disparidades entre meios urbanos e rurais, tanto no relativo à incidência como à mortalidade. Materiais e métodos: o estudo teve como população-alvo os doentes internados no CHUCB entre 1 de Janeiro de 2015 e 31 de Dezembro de 2017 por acidente vascular cerebral isquémico (sub)agudo, classificados com os códigos 163.X no International Classification of Diseases 10. Consideraram-se como factores de exclusão doentes com residência oficial externa, episódios de acidente vascular cerebral de etiologia hemorrágica, casos com ausência de informações suficientes ou com diagnóstico incerto, e ainda episódios ocorridos em doentes na população pediátrica. Calcularam-se as taxas de incidência e mortalidade, tanto brutas como padronizadas, e estudou-se a sua dispersão geográfica a nível de freguesia com o estudo da autocorrelação espacial (I de Moran e c de Geary) e kriging simples de 8 sectores. Considerou-se como estatisticamente significativo um valor-p <0,05. O estudo foi aprovado pela Comissão para a Ética em Saúde do Centro Hospitalar Universitário da Cova da Beira. Resultados: a autocorrelação só foi positiva e estatisticamente significativa no mapeamento do número de novos episódios de acidente vascular cerebral, sendo os resultados contraditórios entre os testes usados e inconclusivos para a incidência e mortalidade padronizadas. Mesmo assim, conseguiram-se identificar 3 clusters de incidência padronizada com a ajuda do kriging e ainda uma zona com mortalidade mais elevada na periferia ocidental do concelho da Covilhã. Os doentes rurais são em média 2,53 anos mais velhos do que os urbanos e a incidência bruta é maior em meios rurais, contudo a padronizada é mais elevada em meios urbanos. A nível concelhio, a incidência é significativamente inferior em Belmonte. Conclusões: a Cova da Beira aparenta ter disparidades geográficas marcadas na incidência de acidente vascular cerebral isquémico, apesar de as suas causas serem desconhecidas. A krigagem pode complementar os testes estatísticos de autocorrelação espacial caso sejam inconclusivos e/ou contraditórios e ser um método auxiliar na detecção de agregados.
- Collision Dynamics of a Single Droplet onto a Heated Dry Surface: Jet Fuel and HVO MixturesPublication . Pinto, Pedro Miguel Moreira; Vasconcelos, Daniel; Ribeiro, Daniela; Barata, Jorge M M; Silva, AndréUnderstanding the phenomena behind droplet impact is essential to improve the effectivenessin many industrial applications, such as fuel injection in an internal combustion engine andrapid spray cooling of hot surfaces. This study focuses on an experimental investigation ondroplet impact onto a heated wall. The purpose of this work is to analyse the influence of walltemperature on the morphology of a single droplet impact and observe the possible outcomes.In these experiments, the observation of all heat regimes was possible. Since there is an urgeto implement biofuels in general aviation, the fluids analysed are fuel based. The fluids usedwere distilled water, as a control group, 100% jet fuel, and a mixture of 50% biofuel with 50%jet fuel. This mixture corresponds to the maximum of renewable energy source fuel due to theminimum of 50% of jet fuel required by civil aviation. The impact energy was kept constant, andthe Weber number was set to 320. Furthermore, different wall temperatures were chosen (25◦C−320◦C) to seek every possible impact phenomenon and characterise the impact morphology.The impact dynamics were captured using a high-speed digital camera and the images weredigitally processed.
- Comparison of Commercial and Open-Source CFD Solvers on Surface Tension Dominated FlowsPublication . Vasconcelos, Daniel; Silva, André; Barata, Jorge M MProblems involving multiphase flows require a physical understanding of how the phenomenadevelop and the specific interactions they manifest. For surface tension relevant flows, suchas bubbles and droplets, the importance of modelling and predicting small-scale behaviouris crucial in accurately defining the liquid-gas interface and complex interactions that may takeplace. Axisymmetric numerical simulations of single droplets impacting onto thin liquid films areperformed using commercial and open-source CFD codes. ANSYS Fluent®is the commercialsoftware employed, whereas Basilisk is the open-source CFD solver adopted. The incompress-ible Navier-Stokes equations are coupled and handled differently throughout each software.A solution-adaptive mesh refinement tool is adopted to reduce computational cost. Softwarecomparison is based on quantitative and qualitative analysis, namely crown height and outerdiameter measurements, and the crown curvature and occurrence of splashing, respectively.Results show that Basilisk simulations are in good agreement with the experimental data. Fluent follows the tendency for the crown outer diameter however, in terms of height, the modelunder-predicts its growth and collapses at later stages of the impact for lower thicknesses