Development and standardization of a protocol for sperm cryopreservation of two important commercial oyster species

Dissertação de mestrado, Aquacultura e Pescas, Faculdade de Ciências e Tecnologia, Universidade do Algarve, 2015Aquaculture activities have a huge contribution for the world food production and their development is extremely necessary to answer to the lack of resources, especially to the demand for seafood. Bivalve production, especially Crassostrea angulata (Portuguese oyster) has been practiced from long ago, and although its production suffered several constraints, in recent years it has been increasing the interests in recovering production and in preserving nature populations. In this sense, new research needs to guarantee an efficient and economically viable production, contributing to a relatively new environmental concern: wild population restoration. Nowadays, pure wild populations of Crassostrea angulata are rare to find due to multiple factors that affected this oyster industry. Cryopreservation technology could promote alternative techniques to contribute for the resource management efficiency of the Portuguese oyster and associated economic activity. In this sense, standardization of procedures is important for Crassostrea genus. At the present there are no cryopreservation reports on Crassostrea angulata sperm, and therefore, one of the objectives of this work is to design a cryopreservation protocol for this species, testing the more adequate cryoprotectant solution, its ideal concentration, different freezing rates and types of containers. In parallel, this stablished protocol was applied in Crassostrea gigas and compared to other previously published for this species. Analysis of motility, viability, agglutination and fertilizations were used as guides for the establishment of the protocol in C. angulata. Moreover, ATP content, DNA fragmentation and lipid peroxidation were done in order to standardize the same protocol for both species. Movement analysis were assessed by CASA system, viability through common staining techniques and flow cytometer, agglutination was quantified according to the scale developed by Dong et al., (2007), ATP content determined by bioluminescence, Comet assay was performed to quantify the DNA fragmentation and lipid peroxidation determined spectrophotometrically by measuring the absorbance of the malondialdehyde (MDA). Significant differences were observed (p<0.05) for lipid peroxidation and fertilization trials whereas ATP content and fragmentation of DNA of the cryopreserved samples did not differ significantly from the control. In C. gigas, the same analysis were performed and did not reveal post-thaw quality differences in the samples cryopreserved with 10% DMSO. The established protocol revealed to be effective and with a low degree of cellular damage on C. angulata sperm and, at the same time, viable to apply in other species, such as Crassostrea gigas

"Pântanos de relações e colchões de cumplicidade": academia e conjugalidade na perspectiva de quatro mulheres intelectuais

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Filosofia e Ciências Humanas. Programa de Pós-Graduação em Antropologia SocialMuitas vezes, aquilo que está mais próximo escapa de nosso escopo antropológico, seja por sua complexidade, seja por sua "naturalidade". Assim, nessa dissertação abordo, através da trajetória de quatro mulheres intelectuais da área das ciências humanas, casadas com outros ntelectuais, como academia e conjugalidade interpelam-se ao longo de suas carreiras. Ao acompanharmos suas histórias de vida e depoimentos suscitam-se questões importantes para os estudos de gênero e estudos demeios intelectuais: quais são as condições de produção de mulheres acadêmicas no Brasil dos últimos 50 anos? Quais os padrões de onjugalidade que emergem dessas trajetórias? Assim, discuto ao longo da minha dissertação as condições do trabalho intelectual feminino, conjugalidade em camadas médias intelectualizadas, cotidiano e competição acadêmica, nomeação e renomeação conjugal e suas relações com um meio de produção autoral. Por fim, essa iniciativa insere-se em uma vertente dos estudos feministas que propõe-se a visibilizar trajetórias acadêmicas-intelectuais-científicas femininas de modo a propor outras linhagens e possibilidades de filiação para nossas disciplinas.Intellectual paths among women: academia and conjugality from four perspectives Things that are closer to us may often evade from our anthropological outlook, either for their complexity or for their "plainness". Thus this dissertation focuses, trough the lifes and narratives of four intelectual women from the field of human sciences, married with intelectual partners, how academia and conjugality combine throughout their careers. As we follow their testimonies and life stories important questions related to gender studies and studies of the intellectual milieu arise: what are the terms for the output of women academics in Brazil along the last 50 years? What are the conjugality patterns that emerge within these life stories? Here I take the time to reflect about the conditions for female intellectual labor, conjugality in middle class and highly educated environments, everyday life and academic competition, marital naming and renaming and its relations with the prosecution of an authorial work. Lastly, this enterprise falls into a strand of feminist studies which seeks to acknowledge intellectual and professional stories of women, as to propose to our canonical histories new lineages and possibilities of filiation

Edible films and coatings from tropical fruits.

bitstream/item/35274/1/AD10001.pd

A crise da dívida soberana em Portugal, no âmbito da governação da UEM

Doutoramento em Estudos de DesenvolvimentoA crise das dívidas soberanas, que afetou a Zona Euro na sequência da crise financeira global de 2008, representou um abalo nos alicerces do projeto europeu. A ambivalência que se formou entre dois grupos de Estados-membros gerou uma divisão que pôs em causa o equilíbrio no seio das instituições que havia assegurado a coesão e solidez da construção europeia. Gerou-se uma dicotomia entre um grupo de países percecionados como responsáveis, cumpridores e competitivos, por oposição a um outro grupo de indisciplinados e pouco produtivos. Esta fronteira composta por argumentos não só técnicos ou políticos, mas também de natureza moral, cavou clivagens que geraram dinâmicas inesperadas na Europa. Portugal foi um caso paradigmático de um Estado-membro afetado, de forma severa, pela referida crise do Euro e que teve de lidar com as indefinições europeias na resposta a esse período conturbado. Na presente investigação, enquadra-se esta crise nas suas origens, caraterísticas e impacto, tal como se aprofundam as soluções (ou falta delas) que foram sendo experimentadas. A análise empírica, por sua vez, centra-se no caso português e, em particular, na forma como as elites políticas, com capacidade de decisão e influência naquele período, avaliaram a crise nos seus diferentes parâmetros: as suas causas, as respostas encontradas, o modelo de concretização dessas soluções e, por fim, os resultados alcançados. Para esse efeito, procedeu-se a um conjunto de entrevistas semiestruturadas, a um inquérito por questionário com uma amostra mais alargada e à análise de conteúdo dos documentos oficiais emanados da troika, que liderou o plano de resgate a Portugal.The sovereign debt crisis, which affected the Eurozone after the 2008 global financial crisis, shook the foundations of the European project. An ambivalence was formed between two groups of Member States, and it generated a division that jeopardized the historical balance that ensured the cohesion and solidarity within the European institutions. One group of countries was perceived as responsible, compliant, and competitive, and – on the opposite - another group was seen as undisciplined and unproductive. This boundary, built not only on technical or political arguments, but also on top of moral assessments, carved out cleavages promoting unexpected moves in Europe. Portugal was a paradigmatic case of a Member State severely affected by the Euro crisis and which had to deal with European uncertainty in response to this challenging time. In this research study, this crisis is framed in its origins, characteristics, and impact, as well as the solutions (or lack of them) that have been experimented. The empirical analysis, in turn, focuses on the Portuguese case and on the way in which political elites of that period, namely with decision-making and influence power, assessed the crisis in its different parameters: its causes, the responses chosen, the execution model and, finally, the results achieved. For this purpose, a set of semi-structured interviews was carried out, as well as a questionnaire survey with a broader sample, and a content analysis from the official documents issued by the troika institutions that led the rescue plan for Portugal.info:eu-repo/semantics/publishedVersio

Momentum predictability in the frequency domain

In this dissertation I extend the analysis of Wang and Xu (2015) of momentum returns predictability to the frequency domain. The extensive literature on momentum has been essentially focused on what causes momentum, the description of momentum across industry sectors and countries and on its risk management. The very few works that addressed the topic of predictability of momentum returns, studied the role of investors psychological biases, market volatility and market liquidity but none of them exploited the frequency domain analysis of the predictors that have been used. I provide evidence that replacing the original predictors used in Wang and Xu (2015) by their frequency components delivers improved predictability

Microbiological assessment of polyether ionophorous and their derivatives against Gram-positive bacteria

Trabalho Final de Mestrado Integrado, Ciências Farmacêuticas, 2020, Universidade de Lisboa, Faculdade de Farmácia.As bactérias podem ser classificadas como Gram-positivas (Gram+) ou Gram-negativas (Gram-), como forma de refletir os dois tipos básicos de invólucro celular bacteriano relativamente à composição e características estruturais. A grande diferença entre estas reside no facto das Gram+ não apresentarem membrana externa, permitindo a passagem de pequenas moléculas através da rede de peptidoglicano. Desta forma há determinados agentes antibacterianos que apenas são adequados para um tipo de bactéria, como é o caso dos antibióticos ionóforos poliéteres, que apenas são eficazes contra bactérias Gram+. Estes antibióticos são um grupo de compostos naturais, usado normalmente como aditivos alimentares, para prevenção de coccidioses, e como promotores de crescimento. Para além destas funções, apresentam grande espectro de bioatividade, como antibacteriana, antifúngica, antiparasitária, antiviral e anti-tumoral. Os ionóforos poliéteres são lipossolúveis, o que lhes permite fazer o transporte de catiões metálicos através da membrana e libertá-los do outro lado da membrana. O complexo formado entre o antibiótico e o ião é normalmente neutro, uma vez que a pH fisiológico o grupo carboxílico do antibiótico está desprotonado. A especificidade destes antibióticos depende do tamanho do local onde o catião se vai ligar. O transporte dos iões leva a que haja um desequilíbrio eletrolítico, que leva ao aumento da pressão osmótica na célula, ao aumento da célula e por fim à morte da célula bacteriana. Deste grupo de antibióticos, fazem parte a monensina, salinomicina e lasalocid, objetos deste estudo. Vários estudos já realizados, demonstraram que a complexação destes compostos com certos catiões, podem originar estruturas com maior atividade contra bactérias Gram+. Assim, este estudo foi desenvolvido com o objetivo de melhor perceber, a forma como a complexação destes antibióticos com o sódio, pode influenciar a sua atividade antibacteriana. Devido ao curto período para realização do trabalho, só foi possível a realização do método “double layer agar hole diffusion”, que nos permitiu verificar como a adição do catião à estrutura original, leva ao aumento da atividade contra bactérias Gram+. No futuro, é necessário repetir este teste, para obter resultados mais conclusivos, bem como realizar outros testes, de forma a poder comparar os resultados.The common classification of bacteria as Gram-positive or Gram-negative reflects the two main types of bacterial cell envelope regarding composition and structural characteristics. The major difference between them is that Gram+ microorganisms do not have an external membrane, which allows the passage of small molecules through the peptidoglycan network. Thus, certain antibacterial agents are suitable for one type of bacteria, such as polyether ionophorous antibiotics, which are only effective against Gram+ bacteria. These antibiotics are a group of natural compounds, often used as food additives, for example to prevent coccidiosis, and as growth promoters. In addition to these functions, they possess a wide spectrum of bioactivity, such as antibacterial, antifungal, antiparasitic, antiviral, and antitumor. Polyether ionophores are lipid soluble compounds, which are able to transport metal cations across the cell membranes and release them inside the cell. The complex formed between the antibiotic and the metal ion is usually neutral since at physiological pH the carboxylic group of the antibiotic is deprotonated. The specificity of these ligands is due to the size of the cage where the cation binds. The transport of metal cations leads to an electrolyte imbalance, which causes disturbance of homeostatic processes and leads to ultimate death of the bacterial cell. This group of antibiotics includes monensin, salinomycin and lasalocid, which were evaluated in the present work. Several studies already carried out showed that the complexation of these compounds with certain cations undergoes formation of structures with higher activity against Gram+ bacteria. Therefore, this study was developed with the aim of understanding, if the complexation of these antibiotics with sodium ions, can influence their antibacterial activity. Due to the short period for carrying out the work, it was only possible to apply the double layer agar hole diffusion method for the evaluation of properties of target compounds. In the future, it is necessary to repeat this test, to obtain more conclusive results, as well as to perform other assays using different techniques.Com o patrocínio da Faculty of Chemistry and Pharmacy, Sofia University

Structural models to estimate financial institution´s default probability

Mestrado em FinançasNeste estudo procurámos, no âmbito do Modelo de Merton (1973), determinar a Distância ao Incumprimento (DD) para uma amostra de bancos Ibéricos. Através da especificação de três diferentes Barreiras de Imcumprimento (DB), foi possivel obter diferentes resultados, sublinhando a importância da DB para output do modelo. Durante a crise, o risco de liquidez foi atenuado pelas políticas de cedência de liquidez levadas a cabo pelo BCE. As definições usadas para db1 e db2, diferem na forma como são tratados os emprestimos do BCE, permitindo implementar um procedimento assente no cálculo da DD para quantificar a redução no risco dos bancos induzida por estas medidas. Os nossos resultados demonstram que as políticas do BCE reduziram o risco de incumprimento dos bancos que constituem a amostra.This paper is intended to model the default probabilities for selected Iberian Financial Institutions through the application of Merton's Model (1973) framework. Through the use of three different Default Barrier (db) definitions, we were able to obtain very different outputs, stressing how crucial db definition is to the structural model output. Throughout this crisis, liquidity risk was, in some dimension, offset by the ECB funding policies. db1 and db2 definitions, differing only on the way Central Bank loans were treated, were convenient to test non-standard applications of the model. In our study we introduce and test a procedure anchored on Distance to Distress calculation, to quantify the reduction in risk induced by ECB measures, finding that ECB actions effectively reduced bank's default risk