Testing Nonlinearities Between Brazilian Exchange Rate and Inflation Volatilities

There are few studies directly addressing exchange rate and inflation volatilities, and lack of consensus among them. However, this kind of study is necessary, especially because they can help monetary authorities to know price behavior better. This article analyses the relation between exchange rate and inflation volatilities using a bivariate GARCH model, and therefore modeling conditional volatilities, fact largely unexplored by the literature. We find a semi-concave relation between those series, and this nonlinearity may explain their apparently disconnection under a floating exchange rate system. The article also shows that traditional tests, with non-conditional volatilities, are not robust.

Quantum Search Algorithms on Hierarchical Networks

The "abstract search algorithm" is a well known quantum method to find a marked vertex in a graph. It has been applied with success to searching algorithms for the hypercube and the two-dimensional grid. In this work we provide an example for which that method fails to provide the best algorithm in terms of time complexity. We analyze search algorithms in degree-3 hierarchical networks using quantum walks driven by non-groverian coins. Our conclusions are based on numerical simulations, but the hierarchical structures of the graphs seems to allow analytical results.Comment: IEEE Information Theory Workshop 201

La competencia de “Lolium perenne” RG afecta el rendimiento de uva y la calidad del vino de la región del Duero

To assess the efficacy of post-emergence herbicide programs in “Lolium perenne” L. populations glyphosate resistant (GR), a field experiment was carried out in a Douro vineyard (North Portugal) in 2014. A random block design (RBD) experiment with 11 treatments and three replicates was implemented. Fruit size, cluster number and grape weight were determined. Quality parameters (pH, total polyphenols anthocyanin content and color intensity) were also analysed. Analyses of variance (ANOVAs) were used to test the effects of weed cover on grape yield and quality. Tukey test was used to determine the differences among group means. The results show that weed cover affects crop productivity but it does not affect fruit composition, and therefore to wine quality.En 2014 se llevó a cabo un ensayo en un viñedo del Douro (Norte de Portugal) para evaluar la eficacia de diferentes herbicidas en post-emergencia sobre “L. perenne” GR. Se evaluó los efectos de la infestación en la productividad y calidad de la uva. La productividad se determinó midiendo el tamaño, peso y número de frutos y racimos. Los parámetros de calidad analizados fueron: pH, contenido de antocianinas, polifenoles totales e intensidad de color. El ensayo se dispuso en un diseño de bloques al azar con 11 tratamientos y 3 repeticiones. Se realizó el análisis de varianza (ANOVA) y la prueba de Tukey para observar las diferencias significativas entre la media de la eficacia, la productividad y la calidad. Los resultados obtenidos mostraron que la producción se vio afectada por la cobertura de “L. perenne”. Sin embargo, la composición del fruto, y por lo tanto la calidad del vino no se vio alterada

Boldness traits, not dominance, predict exploratory flight range and homing behaviour in homing pigeons

This study investigated whether consistent individual differences in behaviour (particularly exploratory tendency and object neophilia) were associated with the tendency to explore in free-ranging scenarios. This was tested in homing pigeons. The results showed that birds that were more likely to explore in the loft were also more likely to explore the local area during self-driven flights. When birds were released from a fixed release points, those which had explored less took more tortuous and longer routes back to the loft. This demonstrates the cost associated with lack of exploratory behaviour, and also links traits measured in laboratory scenarios to behaviour in free-ranging animals

Previsão de séries de tempo na presença de mudança estrutural: redes neurais artificials e modelos estruturais

The Brazilian price stabilisation policies and trade liberalisation measures of this decade have considerably increased the difficulty in generating accurate time series forecasts due to structural changes in the data generation processes. In this paper we provide an empirical evaluation of the forecasting performance of Artificial Neural Networks (ANN) and Structural Time Series models (STS) in the presence of structural change. We are basically interested in evaluating the capability of ANN and STS models in terms of both identifying that a structural change has happened and the speed of adjustment of the one step ahead forecasts after the change. We use both real and simulated time series in these exercises. The simulated series are generated from ARIMA processes with imposed structural changes in the mean and trend. On the other hand, we also use real time series data for the Brazilian inflation rate and total imports. The results for the one step ahead forecasts show that the ANN models present a marginally better perfomance than the STS in the periods just after the structural change