The structure of international stock market returns

The behavior of international stock market returns in terms of their distributional properties, serial dependence, long-memory and conditional volatility is examined. A factor analysis is employed to identify the underlying dimensions of the returns. The analysis reveals the existence of meaningful factors when these are estimated from the empirical properties of a large set of international equity indices. Furthermore, the factor scores discriminate very well the stock markets according to size and level of development.International stock markets; Serial dependence; Long-memory; Conditional volatility; Factor analysis.

Recurrence quantification analysis of global stock markets

This study investigates the presence of deterministic dependencies in international stock markets using recurrence plots and recurrence quantification analysis (RQA). The results are based on a large set of free float-adjusted market capitalization stock indices, covering a period of 15 years. The statistical tests suggest that the dynamics of stock prices in emerging markets is characterized by higher values of RQA measures when compared to their developed counterparts. The behavior of stock markets during critical financial events, such as the burst of the technology bubble, the Asian currency crisis, and the recent subprime mortgage crisis, is analyzed by performing RQA in sliding windows. It is shown that during these events stock markets exhibit a distinctive behavior that is characterized by temporary decreases in the fraction of recurrence points contained in diagonal and vertical structures.Recurrence plot, Recurrence quantification analysis, Nonlinear dynamics, International stock markets

The Structure of International Stock Market Returns

The behavior of international stock market returns in terms of rate of return, unconditional volatility, skewness, excess kurtosis, serial dependence and long-memory is examined. A factor analysis approach is employed to identify the underlying dimensions of stock market returns. In our approach, the factors are estimated not from the observed historical returns but from their empirical properties, without imposing any restriction about the time dependence of the observations. To identify clusters of markets and multivariate outliers, factor analysis is then used to generate factor scores. The findings suggest the existence of meaningful factors which determine the differences in terms of the dependence structure between developed and emerging market returns

On the classification of financial data with domain agnostic features

We compare a data-driven domain agnostic set of canonical features with a smaller collection of features that capture well-known stylized facts about financial asset returns. We show that these facts discriminate better different asset types than general-purpose features. Therefore, financial time series analysis is a domain where well-informed expert knowledge may not be disregarded in favor of agnostic representations of the data.info:eu-repo/semantics/publishedVersio

Toxoplasma gondii: serological study in pigs slaughtered in Portugal

Toxoplasma gondii has a worldwide distribution and usually is not detected macroscopically by traditional meat inspection methods. The aim of this study was to assess the seroprevalence of Toxoplasma gondii in slaughter swine using a modified direct agglutination method (MAT) (Toxo-Screen DA, Biomérieux® SA). No positive results were obtained in sera from 337 animals from 12 intensive production farms tested in duplicate at the dilutions of 1:20 and 1:40. The estimated seroprevalence was 0%. The 95% confidence intervals ranged from 0 to 21.8% within batches, and 0 to 1.1% of all animals. In 10 of the 12 farms, Toxoplasma seroprevalence was below 7% (\u3e99% confidence level). In the remaining two farms, the sampling fraction was too small to distinguish a population with prevalence of 7% from a disease-free population. Our findings suggest that Toxoplasma seroprevalence in intensive pig farms is likely to be below 7%. However, selection of farms was not random, so further studies are required to allow making inferences for all intensive pig farms in the centre and north of Portugal

Remarks on stability of inverted pendula

Using linearization principle and tools from chronological calculus one establishes a criteria for stabilization of, usually unstable, equilibrium position of Double Inverted Pendula when subject an arbitrary fast oscillation. Both, planar and spherical cases are considered.Fundação para a Ciência e a Tecnologia (FCT)Dipartimento di Matematica per le Decisione, Università di Firenze, Itali

Valorization of Waste Cooking Oil into Biodiesel over Heteropolyacids Immobilized on Mesoporous Silica — A Kinetic Study

Biodiesel production from WCO with methanol was carried out over tungstophosphoric acid immobilized on SBA-15 by grafting technique, at 60°C. After PW immobilization, the morphology of the support remained. In order to optimize the conditions, the influence of various reaction parameters, the nature of alcohol and the amount of initial free fatty acid on the transesterification of WCO in the presence of PW-NH2-SBA-15 catalyst were carried out. The esterification/transesterification of WCO with propanol and ethanol led to lower concentration of fatty acid esters than with methanol. When different amounts of free fatty acids (palmitic acid) were added to the WCO, a slight increase on the concentration of FAME was observed. In order to study the catalytic stability of PW-NH2-SBA-15 catalyst, four consecutive batch runs were carried out

AnálisePsicogenética da Inserção dos Jogos de Regras e das Relações Cooperativas no Ambiente Escolar

Trata-se de um estudo sobre a inserção de jogos de regras na escola como estratégia facilitadora do desenvolvimento de relações cooperativas. De acordo com a abordagem psicogenética, o jogo de regras, ao possibilitar trocas entre iguais baseadas na reciprocidade, acaba por favorecer a cooperação. Buscou-se, então, analisar no cotidiano de duas escolas (uma reconhecidamente construtivista e a outra com métodos de ensino ditos tradicionais) as configurações dadas ao jogo de regras e suas possíveis contribuições para a evolução das trocas cooperativas das crianças. Na primeira etapa da coleta dos dados utilizou-se um roteiro de entrevista para os profissionais pedagógicos e um protocolo de observação. Tais instrumentos destinaram-se à caracterização das escolas em termos da utilização de jogos de regras. Em uma segunda etapa foi utilizado um roteiro de entrevista para a investigação de aspectos relacionados à tendência cooperativa dos alunos. Os dados foram sistematizados de forma descritiva, contando vez ou outra com categorizações e buscando compreender em seu conteúdo análises quantitativas e qualitativas. Os resultados demonstraram que a maior presença dos jogos de regras no contexto da escola construtivista foi acompanhada por um maior desempenho cooperativo de seus alunos