ESTG - Artigos em revistas internacionais
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- 2ARTs: A Platform for Exercise Prescriptions in Cardiac Recovery PatientsPublication . Pereira, Andreia; Martinho, Ricardo; Pinto, Rui; Rijo, Rui; Grilo, CarlosDue to limited access, increasing costs and an ageing population, the global healthcare system faces significant coverage problems that call for innovative approaches. Health professionals are actively seeking alternative methods to provide care to an increasingly needy population, without increasing human effort and associated costs. eHealth platforms, which use technology to provide patient care, are emerging as transformative solutions for addressing these problems. This study is centered on the demand for a Decision Support System (DSS) in cardiology to enable doctors to prescribe individualized care inside Cardiac Rehabilitation Programmes (CRPs). The 2ARTs project’s main objective is to include a cardiac rehabilitation platform with a DSS within the hospital infrastructure. This DSS uses models to classify patients into different groups, delivering crucial information to assist with decisions regarding treatment. Regarding the DSS, Principal Component Analysis (PCA) emerged as a standout technique for dimensionality reduction, due to its interoperability with clustering algorithms and superior evaluation metrics. The most appropriate clustering technique was determined to be the K-means algorithm, which was supported by the experts analysis. In accordance with the goals of the 2ARTs project, this integration of PCA and K-means provides meaningful insights that improve reasoned decision-making.
- A 2D ray-tracing based model for wave propagation through forests at micro-and millimeter wave frequenciesPublication . Leonor, Nuno R.; Sanchez, Manuel Garcia; Fernandes, Telmo; Caldeirinha, Rafael F. S.This paper proposes the extension of a 2-D ray-tracing-based model for radiowave propagation in the presence of trees and vegetation areas to include real-sized trees and outdoor forest scenarios. The original propagation model proved to be suitable to characterize the electromagnetic behavior in the presence of indoor tree formation scenarios, despite some limitations found when applied to real-sized trees. In addition, the original propagation model requires the prior knowledge of the trees’ re-radiation function to extract the relevant propagation input parameters, which is not always possible to obtain in outdoor scenarios. Therefore, an empirical method to extract the relevant input propagation parameters based on simple measurements is proposed. The performance of the proposed propagation model extension is extensively assessed in both the line-of-trees and tree formation scenarios, including various (and mixed) species, both in- and out-of-leaf foliation states, and at three signal frequencies. Finally, depending on the type of scenario, a benchmark between the proposed propagation model and both the radiative energy transfer (RET) and discrete RET (dRET) models, for line-of-trees and tree formation, respectively, is presented.
- A 2D Ray-Tracing Based Model for Wave Propagation Through Forests at Micro-and Millimeter Wave FrequenciesPublication . Leonor, Nuno R.; Sanchez, Manuel Garcia; Fernandes, Telmo; Caldeirinha, RafaelThis paper proposes the extension of a 2-D ray-tracing-based model for radiowave propagation in the presence of trees and vegetation areas to include real-sized trees and outdoor forest scenarios. The original propagation model proved to be suitable to characterize the electromagnetic behavior in the presence of indoor tree formation scenarios, despite some limitations found when applied to real-sized trees. In addition, the original propagation model requires the prior knowledge of the trees' re-radiation function to extract the relevant propagation input parameters, which is not always possible to obtain in outdoor scenarios. Therefore, an empirical method to extract the relevant input propagation parameters based on simple measurements is proposed. The performance of the proposed propagation model extension is extensively assessed in both the line-of-trees and tree formation scenarios, including various (and mixed) species, both in- and out-of-leaf foliation states, and at three signal frequencies. Finally, depending on the type of scenario, a benchmark between the proposed propagation model and both the radiative energy transfer (RET) and discrete RET (dRET) models, for line-of-trees and tree formation, respectively, is presented.
- 3-D Mechanically Tunable Square Slot FSSPublication . Ferreira, David; Cuinas, Inigo; Caldeirinha, Rafael F. S.; Fernandes, TelmoWe introduce an innovative 3-D mechanically tunable frequency selective surface (FSS), which is inspired by the classical flat square slot FSS. The proposal improves the performance of classical 2-D FSS designs, and it also represents a novel method of achieving mechanical frequency tuning, despite other 3-D designs that consist of a collection of stacked 3-D layers exist. In our proposal, the rotation of an inner element provides tuning capability to the squared cell structure, consisting of metallic grids with a movable inner element. An aluminum prototype was built, which can be tuned from 2.4 to 4 GHz, and also compared its measured performance and numerical simulations. Some characteristics of the proposed structure are the rejection level at main polarization, up to 20 dB, and the maximum frequency sweep of approximately 50% of the fundamental frequency. The prototype showed a stable frequency response for angles of incidence up to 45°. Since results are in good agreement with simulations, we provide parametric equations to design 3-D structures at desired frequencies.
- 3D bioprinting of photocrosslinkable hydrogel constructsPublication . Brás Pereira, Rúben Filipe; Bartolo, PauloThree‐dimensional (3D) bioprinting comprises a group of biofabrication technologies for the additive manufacturing of 3D constructs by precisely printing biocompatible materials, cells and biochemicals in predesigned spatial positions. These technologies have been successfully applied to fabricate biodegradable 3D constructs with intricate architectures and heterogeneous composition, assuming a pivotal role in the field of tissue engineering. However, the full implementation of bioprinting strongly depends on the development of novel biomaterials exhibiting fast crosslinking schemes and appropriate printability, cell‐compatibility and biomechanical properties. Photocrosslinkable hydrogels are attractive materials for bioprinting as they provide fast polymerization under cell‐compatible conditions and exceptional spatiotemporal control over the gelation process. Photopolymerization can also be performed during the bioprinting to promote the instantaneous formation of hydrogel with high well‐defined architecture and structural stability. In this review paper, we summarize the most recent developments on bioprinting of photocrosslinkable biodegradable hydrogels for tissue engineering, focusing on the chemical modification strategies and the combination of photocrosslinking reactions with other gelation modalities.
- 3D deformations by means of monogenic functionsPublication . Morais, João; Ferreira, MiltonIn this paper, the authors compute the coefficient of quasiconformality for monogenic functions in an arbitrary ball of the Euclidean space $\mathbb{R}^3$. This quantification may be needed in applications but also appear to be of intrinsic interest. The main tool used is a 3D Fourier series development of monogenic functions in terms of a special set of solid spherical monogenics. Ultimately, we present some examples showing the applicability of our approach.
- 3D-printed teeth in endodontics: Why, how, problems and future: A narrative reviewPublication . Reis, Tiago; Barbosa, Cláudia; Franco, Margarida; Baptista, Catarina; Alves, Nuno; Castelo-Baz, Pablo; Martín-Cruces, José; Martin-Biedma, BenjaminThree-dimensional printing offers possibilities for the development of new models in endodontics. Numerous studies have used 3D-printed teeth; however, protocols for the standardization of studies still need to be developed. Another problem with 3D-printed teeth is the different areas of literature requested to understand the processes. This review aims to gather evidence about 3Dprinted teeth on the following aspects: (1) why they are advantageous; (2) how they are manufactured; (3) problems they present; and (4) future research topics. Natural teeth are still the standard practice in ex vivo studies and pre-clinical courses, but they have several drawbacks. Printed teeth may overcome all limitations of natural teeth. Printing technology relies on 3D data and post-processing tools to form a 3D model, ultimately generating a prototype using 3D printers. The major concerns with 3D-printed teeth are the resin hardness and printing accuracy of the canal anatomy. Guidance is presented for future studies to solve the problems of 3D-printed teeth and develop well-established protocols, for the standardization of methods to be achieved. In the future, 3D-printed teeth have the possibility to become the gold standard in ex vivo studies and endodontic training.
- 45S5 BAG-Ti6Al4V structures: The influence of the design on some of the physical and chemical interactions that drive cellular responsePublication . Melo-Fonseca, F.; Lima, R.; Costa, M.M.; Bartolomeu, F.; Alves, Nuno; Miranda, A.; Gasik, M.; Silva, F.S.; Silva, N.A.; Miranda, G.Multi-material Ti6Al4V cellular structures impregnated with 45S5 bioactive glass were designed and produced using Selective LaserMelting (SLM), an additive manufacturing technique, combinedwith Press and Sintering focusing on load bearing components like hip implants. These structures were designed to combine Ti6Al4V mechanical properties and promote bone ingrowth into the structure as the bioactive material (45S5) is being absorbed and replaced by newly formed bone. The influence of these structures design on some of the physical and chemical aspects that drive cellular response was assessed. Roughness, wettability, bioactive glass quantity and quality on the structures after processing and the pH measured during cell culture (as a consequence of bioactive glass dissolution) were evaluated and correlated with cellular viability, cellular distribution, morphology and proliferation on the surface and inside the structures.
- Abordagem conceitual às estratégias de Internacionalização sob pressões institucionais duais para legitimidade e conformidadePublication . Ferreira, Manuel Portugal; Serra, Fernando RibeiroInternacionalizar as operações requer que as empresas multinacionais (EMNs) desenvolvam estratégias capazes de lidar, simultaneamente, com as pressões institucionais externas, para a legitimidade, e as pressões institucionais internas, para a conformidade. Neste artigo conceitual e baseado na literatura de teoria institucional em negócios internacionais, desenvolve-se um conjunto de proposições teóricas sobre quais as estratégias de entrada nos mercados externos seguidas pelas EMNs face aos ambientes institucionais. Com foco predominante no ambiente institucional externo e nas diferenças de desenvolvimento institucional, também aborda a relevância de considerar o ambiente interno. As estratégias de entrada tendem a ser baseadas em modos de baixo envolvimento e em parcerias, como joint ventures, para entrar em países institucionalmente imaturos ou institucionalmente mais distantes. As aquisições e as parcerias podem ser usadas se as pressões institucionais forem menores. Conclui-se com uma discussão geral e o apontamento de questões para pesquisas futuras.
- Abordagem do marketing de relacionamento no ensino superiorPublication . Nunes, Getúlio Tadeu; Lanzer, Edgar Augusto; Serra, Fernando Ribeiro; Ferreira, Manuel PortugalO artigo apresenta uma análise do atual cenário competitivo do Ensino Superior brasileiro, com o objetivo de demonstrar que a utilização de estratégias de marketing é um fator crítico de sucesso para essas organizações. O trabalho trata da existência de barreiras contra uma abordagem de marketing nas universidades, fruto de um modelo de gestão acadêmica desenvolvido tendo como base um mercado sem competição, comprovando que há uma resistência contra o uso de estratégias mercadológicas nas instituições de Ensino Superior. Neste trabalho, são analisadas as estratégias de marketing utilizadas e são discutidos a sua importância e os seus resultados sob um enfoque transacional para, imediatamente, ser feito um confronto dessas estratégias com uma abordagem de marketing de relacionamento. É feita uma revisão teórica sobre o marketing relacional, sempre em paralelo com as teorias do marketing transacional e com imediata contextualização para organizações universitárias.