Browsing by Issue Date, starting with "2016-7-5"
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- The effect of Public Policies Supporting Renewable energy: A comparative study of installed capacity and electricity generationPublication . Pereira, Diogo André dos Santos; Marques, António Manuel CardosoThe design of energy policies, namely those focused on supporting renewable energy sources is crucial for facing the major challenge of combining economic growth and sustainable development. This paper focuses on the 20 countries with the highest electricity production from renewables, and uses a database of policies since 1971. In addition, this paper uses a time-span from 1990 until 2014, which makes it possible to capture the effects of public policies and the drivers that promote renewable energy implementation, in its take-off phase. The paper contributes to the literature by assessing the effects of public policies supporting renewables on both aggregated renewable sources and individual new renewables. Moreover, it contributes by appraising how public policies are influencing both electricity generation and the installed capacity of renewable sources. The characteristics of the panel data require the use of the Driscoll-Kraay estimator with fixed effects to handle them. The results emphasize that the implementation of renewable energy sources has been established essentially by policy-drivers, but that market-drivers are able to promote renewable energy deployment.
- Triangulation of Non-Manifold Implicit Surfaces using Geometric Healing TechniquesPublication . Nguyen, Quoc Trong; Gomes, Abel João PadrãoImplicit surfaces used in geometric modeling are often limited to two-dimensional manifolds because they are defined as zero-set functions that separate the space into binary regions. Non-manifold implicit surfaces containing singularities such as isolated points or self-intersection points are essentially non-polygonizable. Thus, triangulating and rendering such surfaces are not a trival task. This dissertation presents the design and implementation of an algorithm for triangulating and rendering of non-manifold implicit surfaces using geometric healing techniques. The presented algorithm, called Healed Marching-Cubes (HMC), is built on the standard Marching-Cubes algorithm introduced by Lorensen and Cline in 1987[LC87]. In the context of implicit surface triangulation and rendering, there are not many proposed algorithms to solve its typical problems such as self-intersection emerged by non-manifold surfaces. Hence, Healed Marching-Cubes will be a valuable contribution to the field of computer graphics and geometric computing.
- A música como terapia adjuvante no tratamento da doença de ParkinsonPublication . Teles, Luís Filipe Almeida; Baltazar, Graça Maria FernandesAs doenças neurodegenerativas, como a doença de Parkinson, têm um profundo impacto na qualidade de vida dos doentes, afetando as atividades de vida diárias, as relações sociais e familiares, e de forma geral o bem-estar físico e psicológico dos doentes. Este impacto deve-se às alterações motoras (bradicinesia, tremor, rigidez postural e dificuldade em andar) e não motoras (ansiedade e depressão), características da disfunção dopaminérgica associada à doença de Parkinson e que acarretam perdas significativas para o doente. O tratamento da doença de Parkinson é feito maioritariamente com abordagens farmacológicas, sendo o tratamento “gold standard” a levodopa. Este fármaco, assim como os outros usados na doença de Parkinson, ajudam ao controlo dos sintomas motores mas não modificam as alterações não motoras e não alteram o curso da doença. A terapia musical, desde os anos 90, tem sido experimentada como um auxiliar terapêutico na doença de Parkinson. Surgiu inicialmente como uma estratégia para controlar alterações emocionais e psicológicas associadas à doença, tendo posteriormente sido apontada como benéfica também para os sintomas físicos. A terapia musical, através das diversas técnicas, aparece como uma abordagem complementar à terapêutica farmacológica na doença do Parkinson. Os exercícios praticados nas intervenções musicais permitem que através da estimulação rítmica, e devido ao fenómeno de arrastamento, se obtenham resultados a nível dos sintomas motores. Os doentes com doença de Parkinson, após treino rítmico, conseguem ter um caminhar mais simétrico, reduzindo o risco de queda e melhorando a sua postura. A nível dos distúrbios de humor a terapia musical apresentou também resultados positivos. O trabalho aqui apresentado pretende fazer uma revisão crítica dos estudos publicados sobre o uso das terapias musicais na doença de Parkinson, e o seu impacto nos sintomas motores e não-motores e na qualidade de vida global dos doentes.
- Determinantes da Intenção Empreendedora no Ensino Superior Português da Região CentroPublication . Santos, Rui Filipe Pereira dos; Madeira, Maria José AguilarAtualmente existe uma sociedade muito competitiva e, cada vez mais, torna-se relevante incentivar uma atitude empreendedora criando e estimulando empreendedores. O processo empreendedor é uma importante contribuição para a elaboração de novos negócios e empresas, assim como a criação de emprego. Para isso, é importante explorar novas oportunidades e correr riscos. Desta forma, e identificando a importância do empreendedorismo, o objetivo deste estudo consiste em perceber de que forma é influenciada a intenção empreendedora, bem como duas dimensões que desta derivam – a probabilidade empreendedora e a propensão empreendedora, dos estudantes do ensino superior português da região centro, segundo vários fatores determinantes da mesma. Através da revisão de literatura, procura-se explanar os temas essenciais ao presente estudo, assim como os fatores determinantes da intenção empreendedora abordados nesta investigação - o Ensino do empreendedorismo, Autoeficácia, Antecedentes Familiares e Propensão para assumir riscos. Após a explanação teórica, é feita a formulação das hipóteses de investigação. Para o estudo empírico das hipóteses de investigação foram utilizados dados primários, uma amostra de 132 respostas, recolhidas através da aplicação de um questionário online, construído com questões retiradas da versão portuguesa do questionário do EEP (Entrepreneurship Education Project) aplicado em Portugal. O questionário foi aplicado a todos os participantes, das edições de 2010 a 2015, do CEBT (Curso de Empreendedorismo de Base Tecnológica) das instituições de ensino superior português participantes, Universidades de Aveiro, Coimbra e Beira Interior. Analisando os resultados, foi possível concluir que as variáveis Ensino do empreendedorismo, Autoeficácia, Antecedentes familiares e Propensão para assumir riscos, influenciam positivamente a intenção empreendedora dos inquiridos. Relativamente aos resultados da variável Probabilidade empreendedora, conclui-se que apenas o Ensino do empreendedorismo e a Autoeficácia influenciam esta positivamente. Por fim, a variável Propensão empreendedora é influenciada positivamente, apenas, pela Propensão para assumir riscos.
- In vitro assessment of cytochrome P450 2C9 inhibition: tolbutamide as probe substrate and HepaRG cells as human hepatic modelPublication . Gomes, Ana Inês Pacheco Vaz; Alves, Gilberto Lourenço; Ferreira, Ana Filipa da SilvaPharmacokinetics information, especially regarding the drug metabolic profile, is a requirement during the preclinical and clinical development. In vitro methodologies represent more and more useful tools to predict drug safety and toxicity. The cytochrome P450 (CYP450) enzymes are the main responsible for the variability in pharmacokinetics and drug response, being the cytochrome (CYP) 2C9 isoform representative of about 20% of total hepatic CYP450 content, and one of the most important drug-metabolizing isoenzymes. Consequently, the prediction of drug interactions mediated by the inhibition of the CYP2C9 isoenzyme may be of great relevance in the development of new drugs. Due to the fact that HepaRG, a new human cell line derived from a hepatocellular carcinoma, is being considered a promising model to evaluate the in vitro metabolism of drugs, it was herein used for the development of an in vitro methodology for the investigation of CYP2C9 inhibition-based metabolic drug-drug interactions. The high-performance liquid chromatography–diode-array detection (HPLC-DAD) assay developed, enabled the simultaneously quantification of tolbutamide (TOL) and its metabolite 4-hydroxytolbutamide (4-OH-TOL), in HepaRG cell culture medium samples, supporting the subsequent in vitro studies. Chromatographic separation of the analytes (4-OH-TOL and TOL) and the internal standard (IS), carbamazepine (CBZ), was achieved in less than 20 minutes by a gradient elution on a reversed-phase LiChroCART® Purospher Star column (C18, 55 mm × 4 mm; 3 µm particle size), at 35 °C, using a mobile phase composed of phosphate buffer (10 mM) with 0.1% triethylamine (pH 3)/acetonitrile pumped at 0.6 mL/min. The analytes and IS were detected at 230 nm. The method proved to be selective, accurate, precise and linear (r2 = 0.9901) over the concentration ranges of 0.25-200 µM for TOL and 0.25-20 µM for 4-OH-TOL. Furthermore, the absolute recovery of the analytes ranged from 73.2 to 84.8% and their stability was demonstrated in the studied conditions. HepaRG cells were used in the metabolic inhibition studies, in which the reference drugs used as CYP2C9 inhibitors (amiodarone, fluoxetine, ketoconazole, omeprazole and ticlopidine) or flavonoids [baicalein, (-)-epigallocatechin gallate, kaempferol and quercetin] were pre-incubated for 30 minutes, and then TOL (200 µM), a known CYP2C9 probe drug, was co-incubated with the CYP2C9 inhibitors or flavonoids (24 hours). The suitability of the in vitro technique and the experimental analytical procedures developed and validated in the evaluation of potential metabolic inhibition interactions involving the CYP2C9 was demonstrated by the inhibitory effect observed with almost all the concentrations of CYP2C9 inhibitors. Moreover, all the flavonoids also demonstrated to inhibit the CYP2C9 isoenzyme, with exception of baicalein at 50 µM, validating the methodology applicability. This work demonstrated the usefulness of the in vitro assay developed and validated in the HepaRG cell line as a useful in vitro approach to foresee metabolic interactions involving the CYP2C9 isoenzyme inhibition.
- Inspeção técnica e salubridade na habitaçãoPublication . Pinto, Fernando Filipe Almeida; Lanzinha, João Carlos GonçalvesA questão da salubridade na habitação é da maior importância e tem como finalidade garantir e promover a saúde física, mental e social dos indivíduos e da comunidade onde se encontram inseridos, através da satisfação de “necessidades humanas”, tais como fisiológicas, psicológicas, proteção contra contágios ou segurança. Ora um dos requisitos fundamentais dos edifícios de habitação é a garantia aos seus ocupantes de uma vida saudável e segura, pelo que é da maior importância poder dispor-se de instrumentos de implementação prática que permitam verificar as condições necessárias. Por forma a contrariar a degradação do parque habitacional português e garantir as condições de salubridade, conforto e segurança das habitações, torna-se fundamental a existência de uma inspeção técnica inicial e periódica dos edifícios, a exemplo do que acontece noutros países. A presente dissertação foca-se na criação de vários modelos de inspeção, onde se contempla a avaliação das caraterísticas da fração em análise com vista à sua ocupação garantindo-se a existência de todas as infraestruturas e condições necessárias. Para a realização desta dissertação, procedeu-se à identificação de um conjunto de requisitos regulamentares previstos dispersamente na legislação atual em vigor e aplicável aos edifícios novos e existentes. Analisou-se uma pequena amostra sobre a realização de vistorias de habitabilidade e utilização de edifícios por parte das autarquias locais. Reuniu-se todo um conjunto de requisitos regulamentares e procedeu-se à criação dos vários modelos, cujo objetivo passou pela sua aplicação aos casos de estudo, realizando uma avaliação exigencial suportada em fichas de inspeção. Após a aplicação e análise das metodologias, analisam-se os resultados obtidos, tendo como objetivo de avaliar a utilidade e as condições de aplicação dos documentos produzidos a situações práticas de avaliação das condições de salubridade, habitabilidade e utilização.
- On the nexus of energy use - economic development: a panel approachPublication . Gaspar, Jorge Fernando dos Santos; Marques, António Manuel CardosoAt a time when the major concern is the future of the planet, the debate of the distinction between growth and development is ongoing in scientific literature. Traditionally the Gross Domestic Product (GDP) is the indicator commonly used to measure both. However, it is very inefficient to evaluate development. The most prominent indicator as an alternative is the Index of Sustainable Economic Welfare (ISEW). The paper compares the sustainable development proxy (ISEW) with the economic growth measure (GDP), and their relation-ship with energy consumption. The research question is: The usual results for energy-growth nexus found in the literature change with a more suitable indicator to economic development? The traditional hypotheses of the energy-growth nexus are tested through Panel-Corrected Standard Errors estimator (PCSE), for a panel data that contains twenty-two Countries in annual data frequency for the time span 1995-2013. The PCSE is used because in the panel were detected cross-section dependence, serial correlation and heteroscedasticity. The results point out some differences between ISEW and GDP in the energy nexus. It was founded a negative effect from the ISEW on energy consumption, so a new negative conservative hypothesis was founded. The conservative hypothesis was proved for the GDP with energy consumption. It is also noted that for countries having sustainable development, policymakers should review the energy consumption quantity, the way that they manage the trade market, inflation and interested rates optimal levels. Therefore, policymakers should look at ISEW as complementary indicator to GDP and must be adopted by the most countries possible. This may intensify the respect for natural resources, increase the number of energy efficiency policies and improve countries economic welfare.
- Análise de Risco de Mercados AgrícolasPublication . Rodrigues, Karim Jorge de Lima Lobo; Fuinhas, José Alberto Serra Ferreira RodriguesA motivação que conduziu este trabalho foi a constatação da insuficiência de estudos referentes à análise de risco nos projetos agrícolas. Este tema é de vital importância para a implementação de projetos agrícolas, em Cabo Verde, mais particularmente em São Vicente, devido às condições climáticas e geográficas presentes e de modo a que se possam elevar os padrões de segurança e sustentabilidade. Apresenta-se como um suporte de decisão de implementação ou não do projeto, intitulado Análise de Risco de Mercados Agrícolas - Um Projeto na Ilha de São Vicente. Assim, por um lado, os pontos abordados permitiram identificar e analisar os riscos, oportunidades e ameaças (escassez de água, inundações por chuva, entre outros) e constituíram-se como possibilidade de selecionar aqueles que, num contexto de expectativas e necessidades do mercado agrícola São Vicentino, deverão ser controlados, a fim de prevenir potenciais perdas e aumentar a probabilidade de alcançar os objetivos definidos no projeto. Por outro, tal análise permite desenvolver habilidades para tirar benefícios das oportunidades (construção de diques/barragens) e compreender e aplicar as boas práticas de gestão de risco.
- Iminosugar-steroid conjugates as potenctial a-glycosidase inhibitors and antiproliferative agentsPublication . Garcia, Sara Cristina Nobre; Mellet, Carmen Ortiz; Silvestre, Samuel MartinsSteroidal conjugates are actually used in biological, medicinal or supramolecular chemistry, being a target of interest in the design and synthesis of new compounds. A large class of these conjugates are the steroidal glycosides, which includes structurally and biologically diverse semi-synthetic and natural molecules, isolated from a wide variety of both plant and animal species. Another important group of steroid conjugates is formed by steroids and alkaloids. Interestingly, several alkaloids are also glycomimetics, and includes iminosugars such as 1-deoxynojirimycin, and castanospermine. These polyhydroxylated natural and synthetic alkaloids present ability to inhibit glycosidases and have high interest, once they can be used as biological tools in studies concerning glycoconjugates function, targeting and turnover, and as potential therapeutic agents in the treatment of infections, cancer, and metabolic diseases, such as type II diabetes mellitus (DM). Among these, nojirimycin is a D-glucose mimetic and is a selective glucosidase inhibitor, however lacks anomeric selectivity for one type of glucosidases (a or ß). To improve this feature one family of glycomimetics with an endocyclic nitrogen with higher sp2 hybridation character (sp2 iminosugars) was developed based on 1-desoxynojirimycin structure, which has high selectivity for a-glucosidases. Furthermore, it was proposed that the incorporation of axially orientated substituents on pseudoanomeric position can be an important factor in aglycon-based modulation of inhibitory activity and in permeability through biologic membranes. In this context, several new sp2-iminosugar-steroid conjugates were successfully synthesised by the hybridization of a sp2-derivative of 1-desoxynojirimycin and a sterol moiety. These compounds were tested as glycosidase inhibitors, revealing a general high selectivity for a-glucosidases. In addition, a cell proliferation assay through the colorimetric 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide method revealed that, in general, the combination of the two molecules did not lead to an improved cytotoxic effect in comparison with the isolated mother compounds. In addition, it was performed molecular docking studies in order to predict the binding energies and possible interactions with acetylcholinesterase (AcCHE), once it was noticed that dual a-glucosidase and AcCHE inhibitors can be very useful agents on the treatment of type II DM and Alzheimer Disease. The study revealed these compounds can aslo be potential AcCHE inhibition.
- Development of novel 4-azasteroid derivatives as potential 5a-reductase inhibitors Synthesis, biological and computational evaluationPublication . Brito, Vanessa Sofia Figueiredo de; Silvestre, Samuel MartinsThe enzyme steroid 5a-reductase (5AR) is responsible for the NADPH-dependent reduction of testosterone to the androgen 5a-dihydrotestosterone (DHT). The abnormally high 5AR activity in humans results in excessively high DHT levels in peripheral tissues, which has been mainly implicated in the pathogenesis of prostate cancer (PCa) and benign prostatic hyperplasia (BHP). Therefore, the role of DHT had contributed to the interest in finding 5AR inhibitors. Accordingly, several steroidal and non-steroidal inhibitors have been synthesized and tested against 5AR enzymes. Finasteride is a semi-synthetic 4-azasteroid and it was the first 5AR type II inhibitor approved for the treatment of BHP. In addition, it was also demonstrated that dutasteride acts as a 5AR type I and type II inhibitor and turosteride is selective for the type II isoform of this enzyme. Since these compounds have low potency and produce side effects, it becomes necessary to develop more potent and safe compounds. In the present work, several novel 4-azasteroid derivatives were synthesised from testosterone and progesterone, considering the pharmacophore which finasteride, dutasteride and turosteride have in common. Additionally, to introduce a bulky group and improve the affinity to the enzyme, through an aldol condensation reaction, an aldehyde was added in 16-C and 21-C positions of testosterone and progesterone, respectively. The cell proliferation effects of these compounds was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide proliferation assay in NHDF, LNCaP and T47D cell lines, In addiction, the cell viability effects was also analyzed using propidium iodide staning in LNCaP cells. In order to understand the affinity of the new compounds to the 5AR enzyme, molecular docking studies were performed. However, as the 3D structural coordinates of 5AR are not available, the docking studies have to be performed with 5ß-reductase (5BR) enzyme. Docking simulations with androgen receptor, estrogen receptor and CYP17A1 were also accomplished. To evaluate the toxicity of compounds, in silico toxicity studies were realized. In conclusion, the new compounds were successfully obtained in reasonable global yields. Molecular docking results support the information relative to the 5AR inhibition and show that the majority of the novel compounds have a high affinity to 5BR, while a less number of compounds presented low binding energies for the other studied receptors. From in silico toxicity studies, the data showed that compounds with furan substituent, after metabolized, can cause tumorigenic and mutagenic effects. Compound 16-[(4-methylphenyl)methylideny)-4-azaandrost-5-ene-3,17-dione, 6b, is the most promising compound, having a behaviour in LNCaP cell line very similar to which was observed with finasteride and show a lower IC50 than this approved drug in these experimental conditions.