Browsing by Issue Date, starting with "2025-02-03"
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- Exploring the bioactive potential of mushroom aqueous extracts: antimicrobial, antioxidant, and prebiotic propertiesPublication . Afonso, Tiago Barros; Marçal, Sara; Vale, Pedro; Sousa, Ana Sofia; Nunes, João; Pintado, ManuelaMushrooms provide essential nutrients and bioactive compounds, namely glucans, protein, and phenolic compounds. In this study, two aqueous extractions were performed (M1 and M2) using Pleurotus ostreatus, Pleurotus eryngii, and Agrocybe cylindracea. In M1, a hot extraction (extract M1) (90 °C, 700 rpm, 1 h) was performed. In M2, a room-temperature extraction (extract M2A) followed by a hot extraction (extract M2B) (90 °C, 700 rpm, 1 h) of the extract M2A residue was performed. The M2B extracts showed the lowest extraction yields (12.58–21.78%), while the other yields ranged between 30.91% and 46.03%. All extracts had high protein (12.09–32.97 g/100 g of dry extract), glucan (12.69–48.57 g/100 g of dry extract), and phenolic contents (7.90–16.65 mg GAEs/g of dry extract) and high antioxidant (ABTS and ORAC assays), antimicrobial, antibiofilm, and prebiotic activities. So, they have potential to be used as functional ingredients or natural preservatives. Extracts from A. cylindracea stood out since they had higher protein content, antioxidant activity, and prebiotic activity (extract M1) and inhibited a higher number of foodborne bacteria (only extract M2A). However, unlike extracts from P. ostreatus and P. eryngii, at 40 mg/mL, they had cytotoxic effects.
- Which risk-return profiles do traditional bonds offer in comparison to inflation-linked bonds during periods of elevated inflation?Publication . Klein, Robin Patrick; Schliephake, EvaThe preceding years have been characterised by inflationary pressure, thereby emphasizing the importance for investors to understand the dynamics of the different bonds classes within such an environment. This thesis investigates the risk-return profiles of different bonds classes (Treasury inflation protected securities, government-, and corporate bonds) within the recent elevated inflationary period. Using comprehensive bonds data from the period of 2014-2024, this study provides key insides about the impact inflation has on these bonds classes. Additionally, it provides insides about the macroeconomic environment that needs to be evaluated to understand the final impact on the bonds market. My findings reveal that treasury inflation protected securities do not provide superior performance within inflationary periods compared to the other bonds classes. High Yield provides higher risk-rewards as credit quality is negatively correlated with risk-reward. The same is true for short duration. The less duration the less risk-reward is provided, on the Government and the Corporate side. Furthermore, it is evident that central bank actions during the recent inflation period influence the bonds market in a novel manner, as unconventional tools are employed to combat yield curve movements and supply shocks. The thesis concludes that long-duration and lower credit quality offer a more preferable risk-return profile while treasury inflation protected securities limit the downside risk.
- Time-varying safe haven properties of currencies, government bonds and commodities : the role of economic, institutional and geopolitical concernsPublication . Pinheiro, Sebastião Abrantes Marques de Melo; Schliephake, EvaThis thesis introduces an innovative approach that analyses safe haven assets by integrating news-based indices to capture the influence of economic, institutional, and geopolitical concerns on investor behaviour. Unlike traditional studies that focus solely on macroeconomic fundamentals, this framework accounts for complex and often intangible factors, such as regulatory uncertainty or geopolitical tensions, offering a more comprehensive view of safe haven dynamics. Using data spanning 2000 to 2023, I study the performance of currencies, government bonds, and commodities during crisis periods defined by extreme volatility and returns in global equity and uncertainty indexes. The results reveal that safe haven properties vary significantly depending on the nature of the crisis. Currencies, such as the USD and CHF, consistently outperform during economic and institutional crises, benefiting from institutional stability and significant foreign exchange reserves. Government bonds show context-dependent behaviour, with U.S. Treasuries excelling under economic concerns and German Bunds performing strongly during institutional crises. Commodities, like gold, appear as the preferred safe haven during geopolitical conflicts driven by their tangible value, while silver and platinum remain constrained by their industrial demand. These findings highlight the time-varying nature of safe haven behaviour and provide practical insights for investors and policymakers seeking tailored crisis-period strategies.
- O exercício das responsabilidades parentais em caso de divórcio e o problema da residência alternadaPublication . Couto, Ana Margarida Rodrigues; Ferreira, Maria Elisabete da CostaO divórcio extingue a relação jurídica do casamento, e com esta, revela-se necessário determinar certos assuntos. Um destes centra-se na regulação do exercício das responsabilidades parentais no caso de existirem filhos menores. Esta mesma regulação comporta questões, entre as quais se destaca a fixação da residência. A residência alternada surge como um modelo cada vez mais utilizado, pelo facto de proporcionar vantagens ao menor, entre as quais, o crescimento em contacto próximo com ambos os seus progenitores. Porém, haverá circunstâncias que impossibilitam o decretamento deste modelo de residência. A decisão passará pela consideração das circunstâncias concretas da família em questão e da própria criança, uma vez que todas as decisões que interfiram com a sua vida deverão ter em conta o seu superior interesse.
- O superior interesse da criança no âmbito da regulação das responsabilidades parentais em caso de divórcioPublication . Fontes, Beatriz Pinheiro Brum; Ferreira, Maria Elisabete da CostaA presente dissertação tem por objeto de estudo a temática do superior interesse da criança no âmbito da regulação das responsabilidades parentais em caso de divórcio. A realidade mostra ser comum o recurso dos progenitores a tribunal, na tentativa de obter uma regulação das responsabilidades parentais que mais os agrade e respeite os seus direitos, ainda que tal seja contrário ao superior interesse do filho. Face a isto, pretendemos analisar de que modo a lei acautela o respeito pelo superior interesse da criança face a estas situações, analisando também a aplicação dessa lei pelos tribunais nas suas decisões. Para tal, socorremo-nos de diversos acórdãos que versam sobre variadas questões. Não sendo todas essas questões consensuais no seio da jurisprudência, vamos dar maior destaque aos casos de violência doméstica e alienação parental no âmbito parental, por consubstanciarem as situações mais problemáticas e desestabilizadoras do bem-estar da criança. Concluindo que a criança é hoje sujeito de direitos cujos interesses devem prevalecer sobre os demais, percebemos também que, por vezes, a concretização e respeito por esse superior interesse não se verifica, quer seja porque a determinação do que é esse superior interesse não é fácil, decidindo os tribunais em desconformidade com o mesmo, quer seja porque os próprios pais obstaculizam a esse respeito.
- Os mais velhos : a perspetiva enquanto agentes de crime, execução de pena e reinserção socialPublication . Ângelo, Nuno Francisco Sousa Fernandes; Faria, Maria Paula Bonifácio Ribeiro deA presente dissertação tem como objetivo fundamental investigar o fenómeno da criminalidade na população mais velha, analisando em particular a atuação desses indivíduos como agentes de crimes, bem como os desafios enfrentados na execução de penas e na sua reinserção social. Através de uma análise transdisciplinar, este estudo procura compreender a criminalidade perpetrada pelos mais velhos: os tipos de crime cometidos nessa faixa etária, as questões da (in)imputabilidade e o impacto da idade na determinação da pena. No que diz respeito à execução de pena, é abordado o regime de permanência na habitação enquanto alternativa justificada ao cumprimento efetivo de pena, em articulação com o direito à proteção da saúde. O estudo revela ser útil considerar diferentes critérios e fatores na classificação do mais velho, de acordo com a área do saber em análise, devendo o Direito adequar-se ao fenómeno evolutivo do envelhecimento populacional. Esta investigação destaca ainda a escassez e inexatidão de dados estatísticos adequados, o que se traduz na necessidade futura de maior precisão das estatísticas criminais relacionadas com a pessoa idosa. Apesar disso, conclui-se que a imputabilidade penal deve ser a regra para os mais velhos, com exceções apenas nos casos previstos pela lei e que, embora não exista uma norma legal expressa que preveja a atenuação da pena em razão da idade avançada, fatores como a personalidade do agente podem influenciar a sua determinação. Por fim, a investigação aponta para a necessidade de criação de programas específicos de reinserção social dos reclusos mais velhos e sugere a análise e adoção de experiências internacionais, como é exemplo o modelo prisional de Singen, sugestionando melhorias no sistema português.
- The key drivers of corporate long-term debt variationPublication . Correia, José Maria Durão Lino Ribeiro; Bonfim, DianaThe objective of this thesis is to study the determinants of the variation of corporate long-term debt, using data for US firms between 1976 and 2023. This thesis shows that both small and medium firms were the main drivers of the downward trend of corporate long-term debt, from 1976 to 2000 and of the upward trend in the two following decades. From 2021 to 2023 it is reported a downward trend caused by small, medium and large firms. Using an OLS estimator for the regressions, this thesis includes firm specific characteristics, related to hypotheses stated in previous literature, and macroeconomic variables which influence the supply and demand of credit. This thesis reports a negative relation between information asymmetry and corporate long-term debt, robust to all specifications and to different proxies for corporate long-term debt. There is also evidence that the maturity matching hypothesis consistently explains its variation, however, this relationship is not robust to different definitions of corporate long-term debt. The downward trend of corporate long-term debt was explained by the increase of the proportion of long-term US treasuries and by the decrease of the proportion of bonds owned by insurance companies. The increase of corporate long-term debt was partially explained by the decrease of the proportion of insured deposits to bank´s total assets. This thesis suggests that both firm characteristics and macroeconomic variables are relevant in explaining the variation of corporate long-term debt, even though macroeconomic variables become less meaningful, after 2000.
- Leading in the digital age: the role of leadership in organizational digital transformationPublication . Sacavém, António; Machado, Andreia de Bem; Santos, João Rodrigues dos; Palma-Moreira, Ana; Belchior-Rocha, Helena; Au-Yong-Oliveira, ManuelIn the modern digital age, organizations face unprecedented challenges and possibilities while managing the intricacies of digital transformation. Accelerated technological developments, changing customer preferences, heightened competition, and dynamic regulatory environments necessitate companies to synchronize their business goals with technological innovations. Leadership is crucial in steering businesses through changes, requiring a deep understanding of change processes and the capacity to adjust leadership accordingly. This research addresses the central question: How does leadership effectively promote organizational digital transformation? The study examines how leaders can effectively promote the adoption of advanced technologies and the promotion of innovation, by first exploring the nature of digital transformation within organizations and then analyzing the evolving dynamics of leadership in this context. An integrative review of the Web of Science (WoS) and Scopus databases was conducted, using the search terms: “Leadership” and “Digital Transformation”. The findings emphasize that effective leadership is crucial for managing the minutiae of digital transformation, integrating technology into organizational processes to facilitate learning, collaboration, and agility, enabling companies to adapt to market shifts, reduce uncertainty, and enhance decision-making for sustainable growth. By using the right tools and with the right frequency, leaders may develop team cohesion—even at a distance. Attentive digital-age leaders will know how to leverage the right mechanisms, and herein, we hope to give some indication of how that may be achieved, so that digital transformation increases rather than decreases team motivation levels.
- Beyond the numbers : the role of attention in stock returnsPublication . Cruz, Miriam Daniel; Schliephake, EvaThis paper investigates whether the Abnormal Google Search Volume Index (ASVI) predicts Abnormal Returns in the Nasdaq-100, using the company9s names combined with the word 8stock9 as a keyword. Analysing data from all Nasdaq-100 stocks between 2019 and 2023, with weekly frequency, I confirm that (1) the ASVI, as a proxy for investor attention, provides unique insights that the other proxies cannot explain, as in Da et al. (2011). Additionally, I find that (2) an increase in investor attention, captured by ASVI, predicts higher short-term abnormal results, with the strongest effects observed during periods of high market volatility, such as during and after the COVID-19 period. Lastly, I find that (3) an increase in ASVI has a stronger impact on the increase of Abnormal Return for technology stocks. These conclusions were mainly based on the CCEMG model, which is particularly suited for analysing macroeconomic shocks. In contrast, GMM cannot capture these effects without further adjustments.
- Marketing nostalgia : engaging consumers through emotional memories. A study of Super Bowl advertising’s impact on consumer behaviorPublication . Vachon, Coline Marie Muriel; Fernandes, DanielThis dissertation examines the role of nostalgia marketing in engaging consumers through emotional memories, focusing on Super Bowl advertisements. Nostalgia, a bridge between past and present, resonates deeply with consumers by evoking cherished memories. The study investigates how nostalgic advertising influences emotional engagement, brand loyalty, and purchase intentions. Using a quantitative approach, data were collected via an online survey of American residents, assessing nostalgic tendencies, emotional responses, and perceptions of Super Bowl commercials. Statistical analyses revealed that nostalgic advertising significantly boosts emotional engagement, especially during culturally relevant events like the Super Bowl. While demographic factors had minimal direct impact, the perceived importance of Super Bowl commercials enhanced the nostalgic effect. The findings emphasize nostalgia’s strategic role in fostering brand loyalty and consumer connection. Marketers can utilize nostalgic elements such as music, visuals, and storytelling to create impactful campaigns. This research contributes to the academic understanding of nostalgia marketing and highlights its potential in diverse cultural and event contexts.