O comportamento de portefólios de fundos de investimento em diferentes períodos macroeconómicos

Dissertação de mestrado em Economia Monetária, Bancária e FinanceiraO presente estudo tem como objetivo principal a análise do comportamento de portefólios de fundos de investimento em períodos de recessão e de expansão económica. O período em análise situa-se entre 1 de janeiro de 2001 e 30 de junho de 2016, com periodicidade diária. A amostra é composta por 7 portefólios que agregam diversos fundos de investimento agrupados por categorias, são elas: fundos de investimento de ações europeias, fundos de investimento de ações norte americanas, fundos de investimento de ações globais, fundos de investimento de obrigações europeias, fundos de investimento de obrigações norte americanas, fundos de investimento de obrigações globais e fundos de investimento mistos. A metodologia baseou-se numa adaptação do modelo de 5 fatores de Fama e French (2015), através da inclusão de 3 variáveis ao modelo já existente, o risco, a idade e o índice de Treynor de cada portefólio. Posteriormente foi incluída uma variável dummy que assume o valor 1 para períodos de expansão económica e o valor 0 para períodos de recessão. Através do teste Chow (1960) e do teste às variáveis dummy constatou-se que de facto as performances dos portefólios em análise são diferentes para períodos de recessão e para períodos de expansão económica. Verificou-se que os portefólios de fundos de investimento de obrigações registam valorizações tanto em períodos de recessão como em períodos de expansão e que os portefólios de fundos de investimento de ações e de fundos de investimento mistos registam, no geral, desvalorizações no valor da unidade de participação em períodos de recessão e valorizações em períodos de expansão. A variável risco não apresentou resultados iguais aos esperados, o que significa que um aumento do nível de risco não traduz necessariamente um aumento da performance dos fundos de investimento. A variável idade, pelo contrário, apresentou o comportamento esperado em quase todos os portefólios. Ou seja, portefólios mais maduros podem apresentar uma melhor performance. O índice de Treynor afirma uma melhor gestão dos portefólios de ações e do portefólio misto do que dos portefólios de obrigações. Os resultados obtidos apenas poderão ser aplicados aos portefólios em análise não podendo ser generalizados.The main objective of this study is the analysis of the behavior of portfolios of investment funds in periods of economical recession and expansion. The period chosen for this analysis was between 1st January 2001 and 30th June 2016 with daily periodicity. The sample is composed by 7 portfolios that gather a variety of investment funds grouped into these categories: investment funds of European stocks, investment funds of North American stocks, investment funds of global stocks, investment funds of European obligations, investment funds of North American obligations, investment funds of global obligations and mixed investment funds. The methodology used is based on an adaptation of the model of 5 factors of Fama and French (2015), through the inclusion of 3 variables to the existent model: risk, age and the Treynor índex of each portfolio. Then, it was also included a dummy variable that assumes the value 1 for periods of economical recession and 0 for periods of economical expansion. Using both the Chow’s test (1960) and the dummy variables test, it was verified that the performances of the portfolios are indeed different, when it comes to economical recession and to economical expansion. On one hand, we were able to conclude that investment funds of obligations increase their value, whether in recession or expansion periods; on the other hand, we managed to conclude that stocks and mixed investment funds value, in general, both the decrease, when it comes to a recession period, and increase, regarding an expansion period. The risk variable did not present the results as it was expected, which means that an increase in risk does not necessarily mean an enhanced performance of investment funds. On the contrary, the age variable presented the expected results in all portfolios. This means that more mature portfolios may register a better performance. Treynor’s índex tells us that the management of stocks and mixed portfolios is better than the portfolios of obligations. The results obtained can only be used in portfolios analysis and cannot be generalized

Ambientes e vida na terra: Os primeiros 4.0 ga

O planeta Terra tem sofrido alterações ao longo do tempo geológico. Pouco tempo decorrido após a sua formação, há cerca de 4.6 Ga, era uma planeta homogéneo. Durante este longo intervalo de tempo, a Geosfera sofreu diversos processos de diferenciação geoquímica e geológica, responsáveis pelo desenvolvimento da actual estrutura interna da Terra. A formação da Atmosfera e da Hidrosfera ocorreu durante o Hadaico, aproximadamente entre 4.5 Ga e 4.4 Ga. A evolução e interacção dos sistemas terrestres, geosfera, atmosfera e hidrosfera, permitiu que fossem reunidas condições favoráveis ao aparecimento da Vida, há pelo menos 3.8 Ga. As formas de Vida foram-se desenvolvendo em diversos ambiente, constituindo outro importante sistema terrestre, a Biosfera. Este artigo tem como principal objectivo a compilação da informação mais relevante relacionada com os principais eventos e outros episódios significantes, que contribuíram para a origem da Vida e seu suporte, tendo como limite temporal o início do Fanerozóico.Environments and Life – the first 4.0 Ga in Earth: The planet Earth has been changing through the geologic time. The Earth was created about 4.6 Ga ago as a homogeneous planet. During this long period of time, several processes occurred originating the geochemical and geological differentiation of the Geosphere and developing the present internal Earth structure. The formation of the Atmosphere and Hydrosphere occurred during the Hadean, approximately 4.5 Ga to 4.4 Ga ago. The evolution and interaction of these important terrestrial systems (geosphere, atmosphere and hydrosphere) allowed, during Earth history, the development of vital conditions for the emergence of Life, at least 3.8 Ga ago. The first organisms might have appeared from the most diverse environments constituting another important system, the Biosphere. The main objective of this article is to compile the most relevant information related with major geological events and other significant episodes, which have contributed to the emergence of Life and its support throughout geological time until Early Paleozoic.Centro de Ciências da Terra (NCT/UM), do Centro de Ciências da Terra (CCT/UM) e do Centro de Geologia da Universidade do Porto (CGUP). Programa de Financiamento Plurianual da FCT, inscrito no POCTI inserido no III Quadro Comunitário de Apoio, co- financiado pelo Governo Português e pela União Europeia (FEDER

Phytoremediation of mixed contaminated soil enhanced with electric current

Brassica rapa is a plant species that can germinate and grow in mixed contaminated soil with PAH and metals (Cr, Pb and Cd). This plant was selected among 14 plant species for electro-phytoremediation tests because its fast germination and growth in contaminated soil. The influence of type of the electric field (AC, DC) and mode of application (continuous, periodic and polarity inversion) was studied in the electro-phytoremediation tests. The application of 1 ACV/cm potential gradient around B. rapa resulted in the effective elimination of anthracene and phenanthrene, but only minor metal removal. The results of this work suggest that alternating current (AC) may be the most suitable electric field for large scale applications. The spatial configuration of electrodes affects the distribution of the electric field in the soil. Various spatial distribution of electrodes have been tested and it has been identified that parallel anodes and cathodes on the soil surface are the most appropriate configuration for field scale applications. Other configurations can be used to concentrate the contaminant around the growing pant or to transport the contaminants from deep soil layers to the rhizosphere.Ministerio de Educación, Cultura y Deporte | Ref. PRX16/0028

Editorial: natural compounds in food safety and preservation

Research Areas: Nutrition & Dieteticsinfo:eu-repo/semantics/publishedVersio

Analysis and optimization of Mn removal from contaminated solid matrixes by electrokinetic remediation

Electrokinetic remediation is a useful technique for the removal of ionic contaminants in soils, sediments, sludges, and other solid porous matrixes. The efficiency of metal removal and the electricity consumption in the electrokinetic treatment of soils largely depend on electric and physicochemical conditions. This study analyzes the electrokinetic treatment of Mn contaminated kaolinite clay specimen and the influence of voltage, current intensity, moisture content, pH, and facilitating agents on metal removal and energy consumption. The objective of this study is to identify the influence of the typical variables used in electrokinetic remediation. The results showed that the operation at constant voltage or constant current intensity were equivalent in terms of metal removal and energy consumption, as long as the electric field intensity was kept low to minimize the consumption in parallel electrochemical reactions, especially the electrolysis of water. The moisture content had a significant influence on the Mn removal. Moisture content higher that 50 percent resulted in very effective Mn removal as compared with kaolinite specimens with lower moisture. The control of pH in the electrolyte solutions and the addition of facilitating agents (organic acids) enhanced the removal of Mn but increased the electric energy cost. Overall, the best conditions for Mn removal involved low to moderate electric potential difference (10 to 30 V), the use of citric acid as the facilitating agent, and the pH control in the cathode at a slightly acid pH. The electrokinetic treatment of a sludge from a water treatment plant contaminated with Mn was effective when pH control on the cathode was used. Mn and various metals (66% of Mn, 30% of Cu, 56% of Zn, 21% Sr, and 21% of Fe) were removed with moderate electricity and acid consumption

Enginnering cardiac tissue using human induced pluripotent stem cell derivatives: Proteomic characterization of co-cultures of cardiomyocytes and endothelial cells

Prediction of cardiac toxicity effect is extremely relevant in the development of new drugs for different medical applications. In this way, it is important to develop more predictable human cell-based models which physiologically better mimic the human heart and allow the prediction of this toxic effect as well as establish the tools that enable the characterization of these complex cell models. To recreate engineered cardiac tissue, it is essential to reproduce the complexity of the heart by resorting to different cell types. Cardiomyocytes (CMs) are functional contractile units of the heart, and it is known that their communication with endothelial cells (ECs) is crucial for cardiac homeostasis. The aim of this study is to recreate a human pluripotent stem cells (hiPSC)-based cardiac tissue model and evaluate the impact of communication between both cell types on the phenotype of CMs. Co-cultures of hiPSC-CM and hiPSC-EC were established and maintained for 12 days as confirmed by immunofluorescence microscopy. Quantitative whole-proteome analysis was performed using SWATH Mass Spectrometry tools to compare the conditions of hiPSC-CM mono-culture and the co-culture of hiPSC-CM and hiPSC-EC. Our data showed relative increase of expression ratios of morphological maturation-related cardiac proteins in hiPSC-CM co-cultures. In particular, the expression ratios of MYH7/MYH6, MYL2/MYL7, TNNI3/TNNI1 increased 2.4-, 5.1-, and 5-fold, respectively, when compared to the mono-culture condition, indicating that in the presence of hiPSC-EC, hPSC-CM display a more adult- and ventricular- like phenotype. Changes in the extracellular matrix composition were also observed, especially related with the increased expression of ECM proteins in co-culture condition namely, collagens I and III (8.6-fold and 6-fold, respectively), fibronectin (3.5-fold) and thrombospondin-4 (2.5-fold). Other growth factors attributed to the extracellular space (e.g. CTGF, PAI1, CRTAP, IGFBP7, and NPPB) that may be responsible for the communication between both cell types have also shown to be up-regulated in the co-culture condition. The presence of a SMA+ (myofibroblast-like) population in the co-culture condition was observed by immunofluorescence microscopy images, which is in agreement with the more complex and fibrotic extracellular matrix found by whole proteome analysis. Ultrastructure characterization of CMs was carried out by transmission electron microscopy. In both conditions, hiPSC-CM displayed aligned myofibrils composed by sarcomeres with organized Z-disks, A- and I-bands, intercalated discs between adjacent cells as well as abundant mitochondria. Noteworthy, sarcomere length was higher in hiPSC-CM cultured with hiPSC-EC, suggesting structural changes associated with cardiomyocyte maturation. Calcium imaging is being performed to evaluate calcium handling of hiPSC-CMs and their response to drugs. All together our data revealed that promoting the communication of hiPSC-CM and hiPSC-EC induced structural changes in hiPSC-CM associated with maturation. This study provides important insights towards the development of more complex cardiac tissues and establishes potent analytical tools for the characterization of these models. This work was supported by Fundação para a Ciência e Tecnologia (FCT)-funded project CARDIOSTEM (MITP-TB/ECE/0013/2013); and iNOVA4Health UID/Multi/04462/2013, a program supported by FCT/Ministério da Educação e Ciência, through national funds and cofounded by FEDER under the PT2020 Partnership Agreement. BA. was supported by FCT Grant SFRH/BD/52475/201

Benefits of phytoremediation amended with DC electric field. Application to soils contaminated with heavy metals

The objective of this study was to determine the influence of the DC electric current in the physicochemical properties of soil. The electric current may induce changes in pH and electric conductivity that will be reflected in the distribution of the electric potential in the soil specimen. This information will be used for the development of a phytoremediation technology amended with electric current. The results showed that low or moderate voltage gradients (0.67 V/cm) induced small changes in physicochemical properties of soil that do not compromise plant survival. The selected voltage gradient was used in electro-phytoremediation tests in soil contaminated with heavy metals (Cd, Co, Cr, Cu, Pb and Zn). Two plants species adapted to the soil and climate conditions were selected (Brassica rapa L. subsp. rapa and Lolium perenne L.). The electric field enhanced the plant growing, mainly in L. perenne, and increased the phytoremediation of the 6 metals. Mixed cultures of the two plant species showed interesting results for large scale applications

Processos de raciocínio matemático e representações de alunos do 8º ano no tópico das funções

Relatório da Prática de Ensino Supervisionada, Mestrado em Ensino de Matemática no 3º Ciclo do Ensino Básico e no Ensino Secundário, Universidade de Lisboa, Instituto de Educação, 2022Este relatório resulta da intervenção letiva realizada com uma turma do 8.º ano do ensino básico, ocorrida durante a subunidade didática – Gráficos de Funções Afins, no final do 2.º Período do ano letivo 2019/2020. O objetivo deste trabalho reside em compreender os processos de raciocínio matemático e as representações usadas por alunos do 8.˚ ano na resolução de tarefas sobre funções. Para dar resposta a esta problemática formulei três questões orientadoras que se prendem com as características dos processos de raciocínio e as dificuldades sentidas na resolução das tarefas, com as representações privilegiadas pelos alunos e com a noção que revelam de função e ainda com a relação entre os processos de raciocínio e as representações usadas. A lecionação da unidade de ensino seguiu uma abordagem maioritariamente exploratória, tendo como objetivo a aprendizagem dos alunos. Foram utilizadas tarefas diversificadas com características predominantemente exploratórias e privilegiado o trabalho autónomo a pares, bem como os momentos de discussão e a síntese de conteúdos. Os alunos foram avaliados recorrendo à observação e questionamento, à análise das produções escritas dentro e fora da sala de aula e através de uma Questão de Aula. A metodologia de investigação seguiu um paradigma interpretativo e uma abordagem qualitativa, onde fui simultaneamente professora e investigadora. Os principais métodos de recolha de dados foram a observação, com registo áudio e vídeo e as produções escritas dos alunos. A análise de dados focou-se nos processos de raciocínio dos alunos, nas representações utilizadas e nas principais dificuldades observadas. Os resultados evidenciaram a intuição dos alunos na interpretação da relação funcional envolvida na representação gráfica de uma função. No entanto, verificam-se dificuldades na transição do concreto para o abstrato e na atribuição de significado à simbologia utilizada. Estas dificuldades são evidentes sobretudo na capacidade de generalização e na conversão para a representação algébrica de uma função. Ainda assim, apesar das dificuldades identificadas, verificou-se que as tarefas exploratórias focadas em correspondências quantitativas contextualizadas foram facilitadoras do processo de generalização, promovendo a compreensão de conceitos abstratos. As dificuldades observadas na justificação residem essencialmente na capacidade de os alunos comunicarem matematicamente, evidenciando a necessidade de continuar a trabalhar estas capacidades transversais.This report is the result of the teaching intervention carried out with a class of grade 8, which took place during the didactic sub-unit – Affine Function Charts, at the end of the 2nd period of the 2019/2020 school year. The aim of this report resides on the understanding of the processes of mathematical reasoning and the representations used by grade 8 students in solving tasks about functions. In order to achieve this aim, I formulated three guiding questions related to the characteristics of the reasoning processes and the difficulties felt in solving tasks, with the representations privileged by the students and with the notion that they reveal of function and also with the relationship between the reasoning processes and the representations used. The teaching of the didactic unit followed a mostly exploratory approach, aiming for students’ learning. A diversity of tasks were used, with predominantly exploratory characteristics, and the teaching approach privileged autonomous work in pairs, as well as moments of discussion and the synthesis of contents. The students were evaluated using observation and questioning, the analysis of written productions inside and outside the classroom and through a Class Question. The research methodology followed an interpretive paradigm and a qualitative approach, where I was both a teacher and a researcher. Data was collected by observation, with audio and video recording and collection of students' written productions. Data analysis focused on the students' reasoning processes, the representations they used and their main difficulties. The results evidenced the students' intuition in the interpretation of the functional relationship involved in the graphical representation of a function. However, there are difficulties in the transition from the concrete to the abstract and in the attribution of meaning to the symbology used. These difficulties are evident above all in the ability to generalize and convert to the algebraic representation of a function. Even so, despite the difficulties identified, the exploratory tasks focused on contextualized quantitative correspondences facilitated the generalization process, promoting the understanding of abstract concepts. The difficulties observed in the justification essentially reside in the students' ability to communicate mathematically, highlighting the need to continue working on these transversal skills

Estudo da compatibilidade electromagnética de aparelhagem de média tensão

Tese de mestrado. Engenharia Electrotécnica e de Computadores (área de Sistemas de Energia). Faculdade de Engenharia. Universidade do Porto, Instituto Superior de Engenharia do Porto. 200