23 resultados para Northwest Argentina
Resumo:
Fluctuations in Holocene atmospheric radiocarbon concentrations have been shown to be due to variations in solar activity. Analyses of both Be-10 and C-14 nuclides confirm that production-rate changes during the Holocene were largely modulated by solar activity. Analyses of peat samples from two intact European ombrotrophic bogs show that climatic deteriorations during the 'Little Ice Age' are associated with transitions to increasing atmospheric C-14 content due to greater C-14 production. Both ombrotrophic mires, which are positioned c. 800 km apart, register reactions to globally recorded C-14 fluctuations between AD 1449 and 1464 and an almost identical reaction between AD 1601 and 1604.
Resumo:
This article analyzes how Lorca develops the concept of ‘duende’, finding a crucial missing link in the Elogio de Antonia Mercé, ‘la Argentina’ (1930). ‘Duende’ crystallizes around 1929/1930 when the poet explicitly takes into account the art of the dancer in performance. Three aspects of performance are singled out and systematically traced through Lorca's evolving reflections on popular art and the struggle of the modern artist to create the new – from his first lecture on the cante jondo in 1922 to the Arquitectura del cante jondo (1930) and finally Juego y teoría del duende (1933). The conclusion is drawn that it is in the performance and reception of a text – whether it is heard or read – that the artist's agonistic stand between tradition and modernity, repetition and singularity, is played out, in an invitation to the listener or reader to celebrate his or her mortality.
Resumo:
Little is known about the microevolutionary processes shaping within river population genetic structure of aquatic organisms characterized by high levels of homing and spawning site fidelity. Using a microsatellite panel, we observed complex and highly significant levels of intrariver population genetic substructure and Isolation-by-Distance, in the Atlantic salmon stock of a large river system. Two evolutionary models have been considered explaining mechanisms promoting genetic substructuring in Atlantic salmon, the member-vagrant and metapopulation models. We show that both models can be simultaneously used to explain patterns and levels of population structuring within the Foyle system. We show that anthropogenic factors have had a large influence on contemporary population structure observed. In an analytical development, we found that the frequently used estimator of genetic differentiation, F-ST, routinely underestimated genetic differentiation by a factor three to four compared to the equivalent statistic Jost's D-est (Jost 2008). These statistics also showed a near-perfect correlation. Despite ongoing discussions regarding the usefulness of "adjusted" F-ST statistics, we argue that these could be useful to identify and quantify qualitative differences between populations, which are important from management and conservation perspectives as an indicator of existence of biologically significant variation among tributary populations or a warning of critical environmental damage.