Long-Term Evaluation of the Influence of Mechanical Pruning on Olive Growing

In Portugal, olive (Olea europaea L.) groves with the traditional tree density of around 100 trees ha -1, necessitate increasing pruning costs every year. As a result farmers tend to lengthen pruning intervals. With the purpose of studying a mechanised alternative to the expensive, labor-intensive manual pruning practice, the authors established in 1997 field trials with the following three treatments: i) manual pruning with a chain saw; ii) mechanical pruning, performed by a tractor mounted cutting bar provided with 6 circular disc-saws; and iii) mechanical pruning, as in the mechanical pruning treatment, followed by a manual pruning complement. The effect of the above treatments on olive production and on harvesting efficiency was evaluated every year for 8 yr. The harvesting was performed by a trunk shaker, and the remaining non-detached fruits were collected manually. The pruning rate of mechanical pruning (487 trees hour-1man-1) was substantially higher than the values of manual pruning and mechanical+manual pruning, which were the same (20 trees hour-1man-1). Over the 8-yr period, mechanical pruning had an average yield of 36,4 kg tree-1 year-1 which was significantly higher than the 30,1 kg tree-1 year-1 of manual pruning and no significantly different from the 34,1 kg tree-1 year-1 of mechanical+manual pruning. The shaker efficiency was significantly influenced by the year, ranging from 72% to 96%; no significant differences were found between treatments in terms of harvesting efficiency. These tests indicate that after mechanized pruning (horizontal cut at the uppermost part of the canopy) trees can be kept for at least 8 years without any significant loss in olive yield per tree and no effect in harvesting efficiency, therefore reducing costs. Selective manual complement to the mechanized pruning, performed in the same year, does not provide any further advantages in olive yield nor in shaker performance and consequently increasing production costs

Strain partitioning in transpressive shear zones in the southern branch of the Variscan Ibero-Armorican Arc

The Torre de Moncorvo region (NE Portugal) is a key-sector of the Autochthon Domain of the Iberian Terrane. The region experienced Variscan deformation in the southern branch of the Ibero-Armorican Arc wherein the early structures (of Upper Devonian age - D1) denotes the establishment of an heterogeneous sinistral transpressive regime. This regime was also responsible for the development of large-scale left-lateral shear zones whose direction is subparallel to major folds. Finite strains analyses were carried out in the Torre de Moncorvo region using the normalised Fry method on different strain markers: (1) distribution of detrital quartz grains in quartzite rocks of Arenigian-Lanvirnian age; (2) arrangement of oolites in discontinuous Ordovician-Silurian ironstone horizons; (3) the rotation experienced by Skolithos preserved in Lower Ordovician metasedimentary clastic rocks. The results obtained indicate the predominance slightly prolate strain ellipsoids predominate. Nevertheless, the variation of their orientation around mesoscopic folds emphasises the role of strain partitioning in transpressive regime, suggesting that different folding mechanisms were active in the course of the same deformation phase. For the studied cases, tangential longitudinal strain and flexural shear combined with regional sinistral shear seem to be the most common mechanisms of folding. Some of these three-dimensional theoretical models for strain patterns in folds could be used in other regions, where a transpressive regime is inferred

Personalidade e coronariopatia

A incidência das doenças coronárias 1 tem aumentado progressivamente nas últimas décadas, nomeadamente nos países ocidentais, bem como as suas nefastas consequências em termos de morbilidade e mortalidade. Este aumento deve-se em grande parte ao facto dos indivíduos aderirem ao que se descreve como uma vida melhor. As pessoas tornam-se obesas e sedentárias, o avanço tecnico-científico submete-as ao stress e à urgência continuada. Em consonância com este facto, Mota Cardoso (1998) refere que talvez “não seja por acaso que, no início deste século de cidade global e de triunfo das luzes, as doenças cardiovasculares sejam a maior causa de mortalidade dos que tiveram acesso aos seus benefícios”. Assim sendo, as lesões coronárias representam o maior problema de Saúde Pública dos países industrializados. Por outro lado, estas revestem-se de uma importância particular pela perda que representa em anos de vida activa para o indivíduo, família, colectividade e economia. Neste artigo teceremos algumas considerações sobre a influência que a personalidade pode ter no aparecimento das doenças cardiovasculares. Assim, começaremos pela definição de personalidade, sua importância e o papel que a personalidade desempenha no comportamento do indivíduo, tendo em conta a interacção dos diferentes factores. Concluiremos esta análise, destacando alguns estudos efectuados nesta área

A Filosofia Jurídico-Política do Krausismo Português

É sempre com agrado que iniciamos a leitura dum texto que trata o krausismo no nosso país, em particular este que foi objecto de dissertação de doutoramento e que, numa análise escorreita, se centra nos três docentes da Faculdade de Direito da Universidade de Coimbra que, bem vistas as coisas, foram responsáveis pela magna difusão desta corrente neste “reino de noventa léguas”, epíteto, ao que parece, com que Garrett mimoseava o solo que o viu nascer. Cumpre-nos, em primeiro lugar, fornecer uma breve panorâmica sobre esta produção escrita. Deste modo, temos que asseverar que a obra se inicia por uma introdução onde se procura debater a questão das filosofias nacionais e mais em particular da filosofia krausiana portuguesa, discutindo a pertinência de tal conceito. A esta breve exposição segue-se um sumário bosquejo sobre a época histórica em que esta corrente se insere. Após a citada introdução, entra a autora, seguindo o fio lógico anteriormente delineado, no estudo das correntes krausianas. Neste particular, opta por dedicar grande parte do seu labor à exposição da filosofia de Krause (1781-1832), com um pequeno apartado sobre os seus mais conhecidos discípulos: Ahrens (1808-1874) e Tiberghien (1819-1901). No que concerne ao krausismo espanhol, expõe mais enfaticamente a vida e obra de Julián Sanz del Río (1814-1869), Francisco Giner de los Ríos (1839-1915) e Nicolás Salmeron (1838-1908)

Os árabes nos antigos relatos portugueses do Índico

ARABS IN OLD PORTUGUESE ACCOUNTS OF THE INDIAN OCEAN. Arabo- Islamic expansion quickly spread throughout Asia, Africa and Europe and in certain circumstances led to the conversion to Islam of many people that were generically labelled Moors. The arrival of the Portuguese in the East called for a more specific way in which to refer to the population coming from Arabia or that which underwent the process of Arabisation: Arabs, Alarves, Arabians, Bedouins, Maçaris and even names of tribes like Ben Jebra [Banû Djabr]

Forecasting Using Targeted Diffusion Indexes

The simplicity of the standard diffusion index model of Stock and Watson has certainly contributed to its success among practitioners resulting in a growing body of literature on factor-augmented forecasts. However, as pointed out by Bai and Ng, the ranked factors considered in the forecasting equation depend neither on the variable to be forecasted nor on the forecasting horizon. We propose a refinement of the standard approach that retains the computational simplicity while coping with this limitation. Our approach consists of generating a weighted average of all the principal components, the weights depending both on the eigenvalues of the sample correlation matrix and on the covariance between the estimated factor and the targeted variable at the relevant horizon. This "targeted diffusion index" approach is applied to US data and the results show that it outperforms considerably the standard approach in forecasting several major macroeconomic series. Moreover, the improvement is more significant in the final part of the forecasting evaluation period.

Inflation (mis)perceptions in the euro area

There has been a growing interest on inflation perceptions in the euro area, in particular, following the euro cash changeover. It has been pointed out that a gap emerged between observed and perceived inflation since the introduction of the euro notes and coins. Such a statement relies on the fact that inflation perceptions, measured by the well-known balance statistic from the European Commission's consumer survey, hiked after January 2002 and remained high thereafter, as opposed to the observed inflation, which has remained fairly stable. In this paper, we discuss the issue of inflation perceptions measurement, by comparing the balance statistic with an alternative refined measure, which is computed using the probability method. We argue that the balance statistic should be used carefully, as it can induce to misleading conclusions. In fact, we provide, for both euro area and country level, evidence showing that, using the proposed alternative measure, the breakdown in the relationship between observed and perceived inflation did not occur at the time of the euro cash changeover.

Determining the number of factors in approximate factor models with global and group-specific factors

For an approximate factor model, in a static representation, with a common component comprising global factors and factors specific to groups of variables, the consistency of the principal components estimator is discussed. An extension of the well known Bai and Ng criteria is proposed for determining the number of global and group-specific factors. The consistency of the suggested criteria is established and the small sample properties are assessed through Monte Carlo simulations. As an empirical illustration, the proposed criteria is applied to estimate the number of global and country-specific macroeconomic factors for the major euro area countries.

Forecasting hourly prices in the portuguese power market with ARIMA models

As power markets became a recent worldwide phenomenon, electricity prices’ forecast is a new subject for investigators. Due to the electricity’s particularities, a power market has some very specific rules that must be understood before one begins its study. This empirical research presents a comparative study between two forecasting methods of the day-ahead hourly electricity prices in the Portuguese power market: a complete hourly time-series analysis and an hour-by-hour approach, each one for a Summer and an Autumn seasons. My purpose is to check if an exhaustive hourly analysis would improve significantly the energy price forecasts accuracy and, if so, would the additional computing time offsets this improvement. As it is common in energy prices empirical research, we use ARIMA models. To select the models on a first stage, the Mincer- Zarnowitz regression was considered. On a second stage, to compare the models and select the best one in terms of predictive ability, the Harvey-Newbold encompassing test was applied. Some evidence was found that, in accordance to Cuaresma et al. (2004), analysing each hour separately produced better results than considering the complete time series, although the time taken to estimate the models can be an issue for short term predictions. The ARIMA models that captured the weekly effect encompassed the others and produced more accurate forecasts.Com a transformação dos mercados de electricidade num fenómeno mundial, a previsão de preços de electricidade tornou-se num novo tema de estudo para os investigadores. Devido às particularidades da electricidade, um mercado eléctrico tem regras muito específicas que têm que ser compreendidas antes de se iniciar o seu estudo. Este trabalho experimental apresenta um estudo comparativo entre dois métodos de previsão dos preços horários de electricidade para o dia seguinte: uma análise da série horária completa e uma aproximação hora a hora, cada uma delas para um período de Verão e de Outono. O meu objectivo é verificar se uma análise horária exaustiva melhora significativamente a precisão das previsões dos preços de energia e, caso tal se verifique, se o tempo adicional requerido compensa esta melhoria. Como tem sido comum em estudos empíricos sobre preços de energia, utilizámos modelos ARIMA. Para seleccionar os modelos foi considerada a regressão de Mincer-Zarnowitz numa primeira fase. Num segundo momento, para comparar os modelos e seleccionar o melhor no que respeita à capacidade preditiva, o teste de Harvey-Newbold foi aplicado. Encontrámos evidências de que, de acordo com Cuaresma et al. (2004), analisar cada hora separadamente conduz a melhores resultados do que considerar a série temporal completa, embora o tempo requerido para estimar os modelos seja relevante para previsões de curto-prazo. Os modelos ARIMA que captaram o efeito semanal englobavam os outros e produziram previsões mais precisas