Equilíbrios de poder na África Subsariana : do terrorismo islâmico ao falhanço de uma região

Este artigo analisa o actual cenário geopolítico na África Subsariana. Serão considerados alguns indicadores sociais, políticos e económicos dos principais países da região ocidental africana, compreendida entre o Senegal e a Nigéria. Além deste enquadramento em redor das estruturas estatais, daremos uma particular atenção às modificações na natureza do Islão em África – tendo em conta que estamos perante sociedades com elevada percentagem de população muçulmana –, bem como à crescente presença de redes terroristas na região, concretamente a al-Qaeda. Na última parte, analisaremos o comportamento de duas potências internacionais na região, procurando averiguar que tipo de percepções e reacções aos problemas da estabilidade e segurança regionais têm tido a China e os EUA

Forecasting exchange rates in the frequency domain

Since a long a time that the exchange predictability is a hot topic for finance practitioners and researchers. In this dissertation we study the exchange rate predictability using a method that has never been applied in the literature: the frequency domain. The uncovered interest rate parity, studied by Fisher (1896) was the model selected for this investigation. Instead of the original time series applied in Rossi (2013), we applied the Faria and Verona (2017) methodology in the Rossi (2013) framework. The frequency-decomposed predictor method tested in the interest rate differential model, does not improve the exchange rate predictability across the sample and time horizon selected. This conclusion come from a horse race analysis of different exchange rates, different filters and different frequencies.Desde há muito tempo que, a previsibilidade da taxa de câmbio é um tema quente em mente para profissionais de finanças e pesquisadores. Nesta dissertação estudamos a previsibilidade da taxa de câmbio por um método que nunca foi aplicado neste ramo: o domínio de frequências. A taxa de juro, estudada por Fisher (1896), foi o preditor selecionado para esta investigação. Em vez da original série temporal aplicada em Rossi (2013), aplicamos a metodologia de Faria e Verona (2017) na estimativa de Rossi (2013). O método preditor de decomposição em frequência testado no diferencial da taxa de juro, não melhora a previsibilidade da taxa de câmbio em toda a amostra e horizonte temporal selecionado. Esta conclusão vem de uma análise de corrida de cavalos de diferentes taxas de câmbio, diferentes filtros e diferentes frequências

A Encruzilhada Iraniana: Armas Nucleares e Consequências Geoestratégicas

Este artigo analisa a forma como a cultura estratégica da República Islâmica do Irão, em conjugação com a ideologia revolucionária que emergiu com o derrube do Xá Reza Pahlavi, reforça as ambições nucleares dos mullahs. Nesta perspectiva, o propósito de adquirir armamento nuclear deve ser entendido como um objectivo racional. O artigo analisará, ainda, o enquadramento de segurança regional e as consequências que resultarão de um Irão nuclearizado. Dado que a aquisição de armas nucleares pelo Irão previsivelmente conduzirá a um clima generalizado de insegurança regional, abordaremos as opções disponíveis para prevenir a sua aquisição e as suas previsíveis consequências. As opções em aberto aos decisores políticos Ocidentais não podem ser catalogadas meramente como boas ou más; todas as opções invariavelmente acarretam consequências negativas e, nalguns casos, desastrosas. É precisamente neste quadro de opções menos boas que se deve equacionar o eventual uso da força contra Teerã

Competitive Advantages as a Complete Mediator Variable in Strategic Resources, Dynamic Capabilities and Performance Relations in the Car Sales Sector

Taking the resource-based view –RBV- and the dynamic capability view –DCV- as an orientation, the main aim of this study is to develop the mediator role that competitive advantages play in the relations between strategic resources, dynamic capabilities and performance. The study takes place in a dynamic and changing sector: the sale of new cars in Portugal. The results show that (a) achieving competitive advantages, which are decisive for business results, depends on the available strategic resources and the generating of dynamic capabilities, (b) in dynamic and changing sectors strategic resources are essential to generate dynamic capabilities, (c) firms must center their attention on, more than results, the generating of sustainable competitive advantages as these act as a mediator variable of the effect of strategic resources and dynamic capabilities on performance. The data scrutiny uses structural equation modeling (SEM) through PLS as the statistical instrument. The sample comprises 89 firms which sell new cars in Portugal

Oriflame usage of social media to improve sales and recruitment

CEMSThis work project is related to the business project on Oriflame consultants usage of social media to improve sales and recruitment. The report is focused mainly on three aspects: the analysis of social media usage in Poland, and the direct selling industry where Oriflame is inserted; the exposition of the work done throughout the business project with further recommendations for Oriflame to implement, and an analysis of how ROI can be measured in social media campaigns

Deep Learning on SAR Imagery: Transfer Learning Versus Randomly Initialized Weights

Deploying deep learning on Synthetic Aperture Radar (SAR) data is becoming more common for mapping purposes. One such case is sea ice, which is highly dynamic and rapidly changes as a result of the combined effect of wind, temperature, and ocean currents. Therefore, frequent mapping of sea ice is necessary to ensure safe marine navigation. However, there is a general shortage of expert-labeled data to train deep learning algorithms. Fine-tuning a pre-trained model on SAR imagery is a potential solution. In this paper, we compare the performance of deep learning models trained from scratch using randomly initialized weights against pre-trained models that we fine-tune for this purpose. Our results show that pre-trained models lead to better results, especially on test samples from the melt season

In defense of a benign dual hegemony

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Bare Nouns in Brazilian Portuguese: An experimental study on grinding

Much literature has explored the interpretation of the bare singular (BS) in Brazilian Portuguese. Pires de Oliveira and Rothstein (2011) claim that BS nouns are mass because they denote kinds and argue that this explains why only the BS in Brazilian Portuguese can have a non-cardinal interpretation. In this paper, based on an experimental task with Brazilian Portuguese adult speakers, we explore one of their predictions, namely that the ‘volume interpretation’ of the BS cannot be explained as a case of Grinding. Our results show that Grinding and Volume readings of a BS noun are not equivalent (in favor of their hypothesis). We also show that a volume interpretation of a noun is never preferred when a cardinal interpretation is available, but that this can be explained by other lexical and pragmatic factors. We conclude by suggesting that Rothstein’s (in press) distinction between counting and measuring accounts for the fact that non-cardinal readings are not grinding

Comparison of Cross-Entropy, Dice, and Focal Loss for Sea Ice Type Segmentation

Up-to-date sea ice charts are crucial for safer navigation in ice-infested waters. Recently, Convolutional Neural Network (CNN) models show the potential to accelerate the generation of ice maps for large regions. However, results from CNN models still need to undergo scrutiny as higher metrics performance not always translate to adequate outputs. Sea ice type classes are imbalanced, requiring special treatment during training. We evaluate how three different loss functions, some developed for imbalanced class problems, affect the performance of CNN models trained to predict the dominant ice type in Sentinel-1 images. Despite the fact that Dice and Focal loss produce higher metrics, results from cross-entropy seem generally more physically consistent