Browsing by Issue Date, starting with "2020-01-10"
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- Evaluation of the role of miR-9 and miR-29 in amyloid pathway of Alzheimer's diseasePublication . Riscado, Micaela Sofia Ribeiro; Sousa, Fani Pereira de; Pereira, Patrícia Alexandra NunesAlzheimer’s disease (AD) is a neurodegenerative disorder which occupies the 3rd place of the diseases that cause disability and death in the elderly, but their causes are yet in need of a better understanding. Also, the search of the etiopathological path leading from a healthy state to full-blown dementia could help with the establishment of more effective treatments. MicroRNAs (miRs or miRNAs) are small regulatory non-coding RNAs (sncRNA), which are involved in post-transcriptional gene expression regulation. Diverse studies have shown that the expression levels of several miRNAs are decreased in AD patients and, there is also evidence that certain miRNAs can control the pathologic hallmarks related to the biomarkers of AD. The main biomarkers of AD are extracellular deposits of amyloid-ß peptide (Aß) along with an accumulation of intraneuronal hyperphosphorylated form of the microtubule-associated protein Tau. The aim of this dissertation is to study the role of two under-expressed miRNAs in AD, miR-29 and miR-9, that are related to the regulation of messenger RNA (mRNAs) that encode proteins involved in various pathological pathways of AD. The selection of miRNAs with decreased levels was based on the possibility of performing its delivery into the cells, in order to contradict the pathological environment of AD. To accomplish this issue, synthetic miRNAs and precursors of miRNAs (pre-miRNAs) produced by two different methods (chemical and enzymatic synthesis, respectively) were used, in order to evaluate if the preparation method had influence in the biological activity. Thus, the pre-miRNAs were produced in the laboratory through in vitro transcription using a plasmid DNA (pDNA) as a template and were further subjected to a purification step. To evaluate the biological activity of the miRNAs, N2a695 cells (mutated APP expressing neuroblastoma mouse cell line that mimics the pathological pathway of AD) were used as in vitro model. Two different methods were also used for cells transfection, Lipofectamine and chitosan-nanoparticles for RNA encapsulation and delivery. After RNA extraction, the mRNA expression levels were evaluated for the APP, BACE1 and PS1 proteins. The findings demonstrated a silencing effect on the expression of APP mRNA by pre-miR-9 and of the BACE mRNA by miR-29b and pre-miR-29b. In turn, PS1 mRNA levels were decreased after cells transfection with all types of miRNAs/pre-miRNAs used in this study, being the most prominent result obtained by RT-qPCR. Western blot assays were also performed, in order to quantify the expression levels of the proteins in study. In conclusion, a better understanding of how miRNAs act and what are their specific targets may have a major impact on the pharmaceutical industry, because being regulators in the pathologic pathways in certain diseases, such as AD, they can be used as new therapeutic approaches to regulate altered proteins expression in this pathological environments.
- Hybrid Robust Distributed Propulsion Control of Lateral-Directional Flight DynamicsPublication . Monteiro, Alexandra Teles de Lima Ferreira; Bousson, Kouamana; Reis, Ricardo José Nunes dosFixed-wing flying vehicles are usually controlled by means of control surfaces such as elevator, ailerons, and rudder. These surfaces are operated by hydraulic and/or electric actuators. ln case of failure of the control surface systems (i.e., control actuators and coupling devices), the aircraft may suffer damages leading to severe or even fatal crashes. An increasing history of accidents and incidents motivated researchers to investigate the use of propulsion as an emergency flight control and ever since researches on propulsion controlled flying vehicles have gained increased popularity in the last decades, expanding from safety purposes only as investigators realised propulsion control is more flexible than classical control surfaces and propulsion controlled vehicles are prone to highly fast attitude stabilisation and trajectory tracking. Distributed electric propulsion opens even further opportunities for propulsion controlled aircraft, introducing faster response engines with additional thrust capability, granting scale-free integration flexibility and no power lapse as altitude increases. Also, the DEP implementation profits from aero-propulsive coupling benefits, noise reduction with a substantially lower acoustic impact and a positive impact on the environment. Thus, the emergence of the DEP system concept as a control actuator potentiates new capabilities for future aircraft's design, efficiency and robustness, improving the performance of conventional designs, including reducing the traditional control surfaces and decreasing the aircraft's control system vulnerability to engine-out cases. Hence, the present work addresses the issue of robust lateral-directional dynamics control for a propulsion controlled aircraft with parameter uncertainties, aiming to understand how to robustly control an aircraft through its distributed electric propulsion system and how to use this capability to introduce improvements in an aircraft's design. Concretely, the core issue focuses on designing a hybrid robust roll-yaw controller which is able to deal with a standalone propulsion control operation mode as well as a conventional mode, combining, if needed, both propulsion control and control surface operation. The proposed methods are then validated through computational simulation on realistic flight scenarios, namely several levelled coordinated tums and a critical engine failure. Thus, this work shines a light on the distributed electric propulsion technology potential as a control actuator, taking a step towards reducing our environmental footprint in a time where the need for environmentally responsible solutions in aircraft technology is an indisputable concern.
- Sintomatologia Depressiva e Empowerment Psicológico nos Estudantes UniversitáriosPublication . Alves, Inês Patrícia Farinha; Carvalho, Paula Susana Loureiro Saraiva deA sintomatologia depressiva é uma problemática bastante prevalente na comunidade estudantil principalmente nas universidades. São vários os estudos realizados dentro desta população e são visíveis diversos projetos de forma a combater esta sintomatologia. O empowerment capacita as pessoas para a tomada de decisão, pelo que pessoas empoderadas apresentam um fator protetor no que diz respeito ao funcionamento psicológico. Assim, quando os indivíduos têm empowerment, existe uma maior autoeficácia levando à consequente diminuição de sintomatologia depressiva. Este estudo pretende avaliar a relação existente entre sintomatologia depressiva e empowerment em estudantes universitários da Universidade da Beira Interior. A amostra deste estudo é composta por 188 estudantes da Universidade da Beira Interior dos cursos de Engenharia que frequentam o 1º ciclo de estudos. Desta amostra, 43 indivíduos são do género feminino e 143 indivíduos são do género masculino. Para avaliar a presença de sintomatologia depressiva utilizou-se o Center for Epidemiologic Studies – Depression Scale (CES-D) e para perceber o nível de empowerment, a Escala do Empowerment (ES-P). Os resultados demonstram que grande percentagem da amostra não apresenta sintomatologia depressiva (68.4%) enquanto 27.3% poderá apresentar sintomatologia depressiva. Além disto, os sintomas depressivos incidem mais no género feminino. Quanto ao empowerment, 44.6% apresentaram pontuações acima da média. Foi ainda possível concluir que não existe uma correlação estatisticamente significativa entre a existência de empowerment e a presença de sintomatologia depressiva. O contexto universitário deve promover o empowerment do aluno, aumentando a capacidade de resolução de problemas e de tomada de decisão e consequentemente melhorar o seu estado emocional.