980 resultados para Hobson, Victor


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La dehesa española y su homónimo portugués (el montado) son sistemas agrosilvopastoriles mediterráneos que proyectan un paisaje excepcional y de elevados valores patrimoniales. Sobre ellos se ciernen nuevas o renovadas amenazas que comprometen su futuro, en un momento (el actual) de creciente revalorización socio-institucional de sus paisajes. Su declaración como paisaje cultural de Unesco puede constituir un potente instrumento para atajar dichas amenazas, pero requiere de la clarificación de ciertos interrogantes relacionados con las escalas. Este artículo se adentra en el valor universal excepcional de la dehesa y propone algunas claves para sustentar su posible incorporación a la Lista de Patrimonio Mundial de Unesco. El análisis se acomete a nivel de tipos de paisaje, pero se avanzan algunos criterios para la selección de ámbitos concretos y representativos susceptibles de integrar una candidatura como “bien en serie”.

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La doctrina de la Proliferación teórica de Paul Karl Feyerabend ha sido interpretada por sus especialistas como un intento de salvaguardar el ideal del progreso científico. Aunque tales estudios hacen justicia, en parte, a la intencionalidad de nuestro filósofo no explicitan la crítica fundamental que implica para Feyerabend el pluralismo teórico. La proliferación teórica constituye en sí misma una reductio ad absurdum de los distintos intentos del positivismo lógico y del racionalismo crítico por definir la ciencia a expensas de lo metafísico. Este artículo presenta la proliferación teórica como una reivindicación del papel positivo que ocupa la metafísica en el quehacer científico. Se consigna la defensa que hace Feyerabend de la metafísica en cuanto que ésta constituye la posibilidad de superar el conservadurismo conceptual, aumentar de contenido empírico de la ciencia y recuperar el valor descriptivo de las teorías científicas.

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Parkinson's disease (PD)-related dementia affects approximately 40% of PD patients and the severity of this dementia correlates significantly with the density of Lewy body (LB) deposition in the PD brain. Aggregated alpha-synuclein protein is the major component of LB's and the non-amyloid component (NAC) region of alpha-synuclein, residues 61-95, is essential for the aggregation and toxicity of this protein. The current study evaluated the effect of pre-aggregated NAC(61-95) injected into the CA3 area of the dorsal hippocampus of the brain on memory in the rat. Previous research has suggested that oxidative stress processes may play a role in the neuropathology of PD, therefore the effect of treatment with vitamin E, an antioxidant, was also evaluated. Male Sprague-Dawley rats were trained in two-lever operant chambers under an alternating-lever cyclic-ratio (ALCR) schedule of food reinforcement. When responding showed no trends, subjects were divided into four groups. Two groups were injected bilaterally into the dorsal hippocampus with aggregated NAC(61-95) (5 mu l suspension), and two groups were injected bilaterally into the dorsal hippocampus with sterile water (5 mu l). Subgroups were treated with either vitamin E (150 mg/kg in Soya oil) or vehicle (Soya oil) daily. Injection of NAC(61-95) induced memory deficits and vitamin E treatment alleviated these. In addition, NAC(61-95) injections induced activated astrocytes and chronic treatment with vitamin E reduced the numbers of activated astrocytes. These results suggest that aggregated NAC(61-95) and associated oxidative stress, may play a role in the pathogenesis of cognitive deficits seen in PD-induced dementia. (C) 2009 Elsevier Inc. All rights reserved.

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Eleven polymorphic microsatellite marker loci were developed from a Leisler's bat (Nyctalus leisleri) genomic enriched library. Assessment of the usefulness of these markers for population genetics studies of Leisler's bats was carried out by screening 100 specimens sampled from eight locations in Ireland and two in Northeastern France. Both moderately and highly polymorphic marker loci were identified. Five to 28 alleles were found to be segregating per locus with observed heterozygosities values ranging from 28.4 to 94%. Initial evaluation indicates that these microsatellites will be useful for genetic based studies aiming, for instance, at parentage and population structure of Leisler's bats.

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Relatively little is known about the biology and ecology of the world's largest (heaviest) bony fish, the ocean sunfish Mola mola, despite its worldwide occurrence in temperate and tropical seas. Studies are now emerging that require many common perceptions about sunfish behaviour and ecology to be re-examined. Indeed, the long-held view that ocean sunfish are an inactive, passively drifting species seems to be entirely misplaced. Technological advances in marine telemetry are revealing distinct behavioural patterns and protracted seasonal movements. Extensive forays by ocean sunfish into the deep ocean have been documented and broad-scale surveys, together with molecular and laboratory based techniques, are addressing the connectivity and trophic role of these animals. These emerging molecular and movement studies suggest that local distinct populations may be prone to depletion through bycatch in commercial fisheries. Rising interest in ocean sunfish, highlighted by the increase in recent publications, warrants a thorough review of the biology and ecology of this species. Here we review the taxonomy, morphology, geography, diet, locomotion, vision, movements, foraging ecology, reproduction and species interactions of M. mola. We present a summary of current conservation issues and suggest methods for addressing fundamental gaps in our knowledge.