Alpha generation with Twitter’s daily momentum

This thesis does not set out to focus on the dynamics relationship between Twitter and stock prices, but instead tries to understand if using relevant information extracted from tweets has the power to increase investors’ stock picking ability, and generate alpha in portfolio’s choice relative to a benchmark. Despite the short period analyzed, it gives promising results that the sentiment analysis performed by Social Market Analytics Inc. applied to an equity portfolio, is able to generate positive abnormal returns, statistically significant in and out of sample.

Equidade na utilização de medicamentos em Portugal

RESUMO - Este estudo teve como objectivo contribuir para o conhecimento sobre a equidade no sector do medicamento, com uma análise empírica aplicada ao sistema de saúde português. Para o efeito avaliou-se se indivíduos com as mesmas necessidades em saúde, mas com diferentes níveis de rendimento, tiveram idêntica prestação no que diz respeito ao medicamento. Adicionalmente, aprofundou-se esta análise através da identificação de factores associados ao sistema de prestação ou ao utente que contribuíram para gerar iniquidades, com particular destaque para os comportamentos de não aquisição de medicamentos – não adesão primária. A avaliação da equidade foi efectuada através de duas abordagens distintas, mas complementares: uma sob a perspectiva da utilização e outra sob a perspectiva da distribuição da despesa pública com medicamentos. Para estas análises aplicaram-se métodos baseados nos índices de concentração, utilizando dados do Inquérito Nacional de Saúde 2005/06 e dados relativos aos encargos do Serviço Nacional de Saúde com medicamentos. Os resultados revelaram que, perante as mesmas necessidades, o sistema de prestação tende a favorecer os indivíduos de nível socioeconómico superior, quer na utilização quer na distribuição de recursos do Estado com medicamentos. Adicionalmente, a aplicação do método da decomposição do índice de concentração revelou que tanto o rendimento como o nível educacional são atributos individuais que estão associados à iniquidade na utilização de medicamentos. A iniquidade observada neste estudo pode resultar de barreiras em diferentes fases do processo terapêutico, entre as quais se destacam o não acesso à prescrição médica ou a não aquisição dos medicamentos prescritos. Foi este comportamento - designado de não adesão primária - que se analisou na segunda parte da tese. Para tal cruzaram-se os dados de prescrição electrónica com os dados de dispensa no Serviço Nacional de Saúde. Os resultados revelaram que a taxa de não adesão primária foi cerca de 20% e que este comportamento está associado ao sexo feminino ou ser jovem, assim como a características do sistema de prestação como o valor dos copagamentos. Estes dados indiciam que as barreiras na aquisição podem ser indutoras de iniquidades na utilização de medicamentos. A identificação de iniquidade na utilização de medicamentos e dos factores que contribuem para esta situação constituem o primeiro passo para uma estratégia de redução da iniquidade que, de acordo com os resultados desta tese, deve abranger não só o sistema de saúde mas também outras áreas das políticas públicas em Portugal.

Cohesion decay: quantitative analysis of partial sister chromatid cohesion

Cell division is a highly dynamic process where sister chromatids remain associated with each other from the moment of DNA replication until the later stages of mitosis, giving rise to two daughter cells with equal genomes. The “molecular glue” that links sister DNA molecules is called cohesin, a tripartite ring-like protein complex composed of two Structural Maintenance of Chromosome proteins (Smc1 and Smc3) bridged by a kleisin subunit Rad21/Scc1, that together prevent precocious sister chromatid separation. Accumulating evidence has suggested that cohesion decay may be the cause of segregation errors that underlie certain human pathologies. However it remains to be determined how much cohesin loss abolishes functional sister chromatid cohesion. To answer these questions, we have developed different experimental conditions aiming to titrate the levels of cohesin on mitotic chromosomes in a precise manner. Using these tools, we will determine the minimal amount of cohesin needed to confer functional cohesion. The approaches described here take advantage of a system in Drosophila melanogaster where the Tobacco Etch Virus (TEV) protease can cleave the Rad21 subunit of cohesin leading to precocious sister chromatid separation. Firstly, we tried to express different levels of TEV protease to obtain partial loss of cohesion. However, this approach has failed to produce systematic different levels of sister chromatid separation. Most of the work was therefore focused on a second strategy, for which we established strains with different levels of cohesin sensitive/cohesin resistant to TEV protease. Strains containing different amounts of functional cohesin (TEV resistant) were tested by in vitro cleavage and by in vivo injections in embryos for their ability to promote sister chromatid cohesion. Our results reveal that removal of half of the cohesin complexes does not impair chromosome segregation, implying that chromosome cohesion is less sensitive to cohesin amounts than previously anticipated.

Planning and verification of multipath routing protocols

Conventionally the problem of the best path in a network refers to the shortest path problem. However, for the vast majority of networks present nowadays this solution has some limitations which directly affect their proper functioning, as well as an inefficient use of their potentialities. Problems at the level of large networks where graphs of high complexity are commonly present as well as the appearing of new services and their respective requirements, are intrinsically related to the inability of this solution. In order to overcome the needs present in these networks, a new approach to the problem of the best path must be explored. One solution that has aroused more interest in the scientific community considers the use of multiple paths between two network nodes, where they can all now be considered as the best path between those nodes. Therefore, the routing will be discontinued only by minimizing one metric, where only one path between nodes is chosen, and shall be made by the selection of one of many paths, thereby allowing the use of a greater diversity of the present paths (obviously, if the network consents). The establishment of multi-path routing in a given network has several advantages for its operation. Its use may well improve the distribution of network traffic, improve recovery time to failure, or it can still offer a greater control of the network by its administrator. These factors still have greater relevance when networks have large dimensions, as well as when their constitution is of high complexity, such as the Internet, where multiple networks managed by different entities are interconnected. A large part of the growing need to use multipath protocols is associated to the routing made based on policies. Therefore, paths with different characteristics can be considered with equal level of preference, and thus be part of the solution for the best way problem. To perform multi-path routing using protocols based only on the destination address has some limitations but it is possible. Concepts of graph theory of algebraic structures can be used to describe how the routes are calculated and classified, enabling to model the routing problem. This thesis studies and analyzes multi-path routing protocols from the known literature and derives a new algebraic condition which allows the correct operation of these protocols without any network restriction. It also develops a range of software tools that allows the planning and the respective verification/validation of new protocols models according to the study made.

Portfolio optimization with options

A Work Project, presented as part of the requirements for the Award of a Masters Degree in Finance from the NOVA – School of Business and Economics

Equity in the fiscal benefits associated with private health expenditures in Portugal: 2000 - 2010

A Work Project, presented as part of the requirements for the Award of a Masters Degree in Economics from the NOVA – School of Business and Economics

Bond portfolio diversification

Portfolio diversification benefits have been extensively documented and acknowledge in the literature since 1952. However, the majority of the studies have focus on an equity context, and only very few on bonds. The study purposed tries to understand and measure the diversification benefits for a pure bond portfolio by investing in securities with different credit risks, maturities and even geographies. Diversification benefits were achieved under the proposed model and some conclusions were withdrawn.

The Cornerstones of Modern Government Maps, Weights and Measures and Census in Liberal Portugal (19th century)

Thesis submitted for assessment with a view to obtaining the degree of Doctor in History and Civilisation from the European University Institute

Going with the wind: The time for time-of-use tariffs

A Work Project, presented as part of the requirements for the Award of a Masters Degree in Management from the NOVA – School of Business and Economics

Speed and rhythm in organizations: How do different generations cope with speed and rhythm at work?

A Work Project, presented as part of the requirements for the Award of a Masters Degree in Management from the NOVA – School of Business and Economics

Strategic assessment of Portugal Ventures' life sciences portfolio

A Work Project, presented as part of the requirements for the Award of a Masters Degree in Management from the NOVA – School of Business and Economics

Customer Lifetime Value: a framework for application in the insurance industry - Building a Business Process to Generate and Maintain an Automatic Estimation Agent

Research Project submited as partial fulfilment for the Master Degree in Statistics and Information Management

Comparative analysis of multicriteria decision making methods

Dissertação para obtenção do Grau de Mestre em Engenharia Electrotécnica e de Computadores

Equity in access to MRI equipment: the Portuguese case

Magnetic resonance imaging (MRI) is a method of image diagnose proven to be of undeniable importance when it comes to neuro and cardio related diseases. In fact, these diseases (such as: ischemic heart disease, stroke and acute myocardial infection) have high incidence in Portugal. For these reasons, the allocation of this medical technology should not be considered with light thoughts. In fact, making decision of resource allocation in health care can be a very complex and contested matter. The impacts of new technology allocation, such MRI, can be assessed in a variety of ways. However, a fundamental component should always be present: the use of evidence-based decision-making methods. One of these methods is Technology Assessment (TA). This paper aims to characterize the equity on access of the Portuguese population in general, to a specific medical device such as MRI, under the TA point of view. It is hoped to promote a bridge of scientific knowledge between the gap on research and policy-making through TA that can emerge as a tool to aid decision-makers in the organization of health systems. There are gaps in providing healthcare, due to geographical imbalances, with some areas unable to provide certain specialized services, as hospitals in the countryside do not provide all medical specialties. Portugal has also a large independent private sector that provides diagnostic and therapeutic services to NHS users under contracts called conventions. These medical contracts cover ambulatory health facilities for laboratory tests and examinations such as diagnostic tests and Radiology. However, there is no convention from the NHS when concerning the MRI exam. Therefore, this reality can be considered a limitation in the access of the general population to this kind of clinical exam. TA can play an useful and important role in helping the decision-makers to explore potential gains that might be achieved by introducing a more rational decision making into health care management, namely into the Radiology area, regarding the allocation of MRI equipment.