The accidental release of 26 African honey bee queens (Apis mellifera scutellata) in Brazil in 1957 was the beginning of the Africanization process of honey bees in South America. This was highly impacting on beekeeping across the continent, because, despite being more productive, African honey bees were very aggressive. Many attempts to cross European x African bees were done in order to obtain less aggressive bees (Michener, 1975). There are slight morphological differences between African and European honeybees. In terms of beekeeping management, however, behavioral differences are more important. Besides stinging, another important difference is hygienic behavior. African honeybees are known to be more effective in eliminating dead larvae and pupae than their European counterparts (Guzman-Novoa et al., 1999). Despite the Africanization, there are still regions with a predominance of European subspecies. For example, in Argentina, there was a significant introduction of European subspecies in highly saturated Africanized honey bee regions in order to slow down the Africanization process. This provided more European gene frequency in

realizado na Casa do Médico, de 7 a 10 de Abril de 2010, tendo como membros da

The purpose of this paper is to test the (rational) expectations hypothesis of the term structure of interest rates using Portuguese data for the interbank money market. The results obtained support only a very weak, long-run or “asymptotic ” version of the hypothesis, and broadly agree with previous evidence for other countries. The empirical evidence supports the cointegration of Portuguese rates and the “puzzle ” well known in the literature: although its forecasts of future short-term rates are in the correct direction, the spread between longer and shorter rates fails to forecast future longer rates. In the single equation framework, the implications of the hypothesis in terms of the predictive ability of the spread are also clearly rejected.

In this paper, it is demonstrated by simulation that, contrary to a widely held belief, pure seasonal mean shifts — i.e., seasonal structural breaks which affect only the seasonal cycle — really do matter for Dickey-Fuller long-run unit root tests. Both size and power properties are affected by such breaks but using the t-sig method for lag selection induces a stabilizing effect. Although most results are reassuring when the t-sig method is used, some concern with this type of breaks cannot be disregarded. Further evidence on the poor performance of the t-sig method for quarterly time series in standard (no break) cases is also presented. Keywords: unit roots; seasonality; Dickey-Fuller tests; structural breaks.

the frequency of oscillations. In this work we extended the classical nonlinear lumped-parameter model of alpha rhythms, initially developed by Lopes da Silva and colleagues [Kybernetik 15 (1974) 27], to generate more complex dynamics. We show that the whole spectrum of MEG/EEG signals can be reproduced within

The cerebellar Purkinje cell is among the largest and most complex neurons in the mammalian brain. The 150,000 to 175,000 granule cell inputs received by each Purkinje cell (Harvey and Napper, 1991) constitute the most massive synaptic convergence found on any neuron in the brain (Shepherd, 1990). Purkinje cells are also distinguished by high densities of Ca2+ channels on the dendrite and by a complex apparatus controlling cytoplasmic Ca2+ concentrations, e.g., with cytoplasmic Ca2+ stores possessing IP3 and ryanodine receptors (Brorson et al., 1991), metabotropic receptors (Llano et al., 1991; Staub et al., 1992) and Ca2+ inflow through the Ca2+ channels (Hockberger et al., 1989; Lev-Ram et al., 1992). Numerous physiological (Llinás and Sugimori, 1992) and biochemical studies (Ito, 1984) have provided the neuroscience community with a wealth of details on the firing properties of Purkinje cells in vitro and on the identity and kinetics of synaptic and ionic channels, but an integrated view of how all these

A lo largo de los años ha realizado diferentes estudios con el objetivo de evaluar los efectos fisiológicos resultantes del consumo de carbohidratos de lenta digestion, los llamados de bajo índice glucémico (IG) y sus efectos en la oxidación de la grasa, en el intento de encontrar estrategias dietéticas que faciliten la obtención de una composición corporal satisfac-toria. De acuerdo a lo expuesto, el objetivo de la investiga-ción fue analizar estudios en que se haya evaluado en qué medida el consumo de una dieta con bajo IG afecta a la com-posición corporal, dando énfasis al efecto de la oxidación de la grasa. La investigación se hizo por medio de búsqueda en Internet de artículos en inglés y/o portugués, publicados desde 1995, y para eso se usó las palabras llave glycemic index, glycemic load, glycaemic index, glycaemic load, body fat, body composition, fat oxidation. Fueron incluidos artícu-los que evaluaban ensayos clínicos en animales y/o huma-nos. Los datos fueron recogidos y estudios utilizando datos encontrados en los sitios: Web of Science, Science Direct y Pubmed. Se averiguó que los resultados en la mayoría de los estudios señalan que el consumo de una dieta de bajo IG se produce una baja respuesta insulínica, aumentando la oxi-dación de la grasa corporal. Estos resultados indican que la ingestión de dieta de bajo IG es una estrategia importante para ser utilizada en la prevención y control de la obesidad y también de las enfermedades crónicas a ella asociada.

The alpha rhythm is the most prominent feature observed in the human electroencephalogram (EEG), and is strongest when the subject is in an eyes-closed relaxed state (Niedermeyer and Lopes da Silva, 2004). It is suppressed by attention or mental effort,

possible role of midbrain dopamine neurons in short- and long-term adaptation of saccades to position-reward mapping. J Neurophysiol 92: 2520–2529, 2004. First published May 26, 2004; 10.1152/ jn.00238.2004. Dopamine (DA) neurons respond to sensory stimuli that predict reward. To understand how DA

What is the effect of peripheral muscle fatigue, pulmonary function, and body composition on functional exercise capacity in acromegalic patients? AgnAldo José lopes, PhD1)*, déborA pedrozA guedes dA silvA, MSc1),