Contaminação por mercúrio em sedimento e em moluscos do Pantanal, Mato Grosso, Brasil Mercury contamination in sediment and in molluscs of Pantanal, Mato Grosso, Brazil

<abstract language="eng">The total level of mercury detected in the sediment and in the tissues of molluscs from the Bento Gomes basin, although low, have shown that the mercury used in the gold mining activities in the Poconé wetlands has contaminated those aquatic habitats in Pantanal. From 69 sediment samples analyzed, 26 % (N = 18) have shown levels ranging from 0.01 to 0.25µg.g-1 of mercury (moist weight). Mercury levels analyzed in 54 samples of mollusc tissues (Ampullaria scalaris Orbigny, 1835; A. canaliculata Lamarck, 1819 and Marisa planogyra Pilsbry, 1933) have shown that 30% (N = 16) were contaminated with levels ranging from 0.02 to 1.16µg.g-1 moist weight. This study shows that the mercury used in digs for gold mining and released into the environment has reached the habitats of Pantanal spread from the sediment into the molluscs living in the region

Diferenciais de produtividade e taxa de câmbio real nas economias desenvolvidas e em desenvolvimento Productivity differentials and the real exchange rate of developed and developing economies

Nos países onde a renda per capita é mais elevada, o nível de preços também é mais alto vis-à-vis os países onde a renda per capita é mais baixa. Esse fenômeno está associado à apreciação da taxa de câmbio real nos países mais ricos e à depreciação dessa taxa nos mais pobres, no longo prazo. O modelo de diferenciais de produtividade de Balassa (1964) e Samuelson (1964), o modelo de dotação relativa de fatores (Heckscher-Ohlin) e o modelo de gostos não homotéticos de Bergstrand (1991) apresentam diferentes explicações para esse fenômeno, e estão testados na literatura empírica do comércio internacional. O modelo de diferenciais de desenvolvimento do "complexo de serviços" está elaborado em Lemos (1988) e foi testado recentemente por Matos e Resende (2005), para o caso do Brasil. Com base neste último trabalho, estimou-se neste estudo uma equação da taxa de câmbio real para um grupo de países desenvolvidos e para outro de países em desenvolvimento (1957-2004). Adotou-se o método de estimação de Johansen. Os resultados corroboram a hipótese do modelo de diferenciais de desenvolvimento do complexo de serviços.<br>In countries where per capita income is high the price level is higher than the level observed in countries where per capita income is low. This phenomenon is associated with real exchange rate appreciation in the rich countries and with the real exchange rate depreciation in the poor countries, in the long-term. The productivity-differential model (Balassa, 1964; and Samuelson, 1964), the relative-factor-endowments model (Heckscher-Ohlin) and Bergstrand's (1991) non-homothetic tastes model, give different explanations for this phenomenon, and have already been tested on the empirical literature on international trade. The differentials development of the service complex model was elaborated by Lemos (1988) and was tested recently by Matos & Resende (2005), in the case of Brazil. Based on Matos & Resende (2005), in this paper an equation for the real exchange rate of a group of developed economies and of a group of underdeveloped economies was estimated (1957-2004). The econometric procedure used was based on the Johansen method. The results do not reject the hypothesis put forward in this paper

Delay, probability, and effort discounting in drug addiction

Impulsivity is a core characteristic of substance abuse in that negative consequences of drug use are devalued in favor of the rewarding effects of the drug. Discounting paradigms are rooted in behavioral economics and are a common measure of impulsive decision making in the addiction literature. Delay discounting, or devaluing future rewards over immediate rewards, has been widely used to assess discounting; however less attention has been paid to other variables such as probability and effort. This chapter discusses the extant research on probability and effort discounting in relation to addiction, which has yielded mixed results and it is yet unclear how addiction relates to impulsive decisions regarding probability and effort. Here, we also discuss the current literature and provide a strong foundation for future investigations in the field of probability and effort discounting