Why is VO2 max after altitude acclimatization still reduced despite normalization of arterial O2 content?

[EN] Acute hypoxia (AH) reduces maximal O2 consumption (VO2 max), but after acclimatization, and despite increases in both hemoglobin concentration and arterial O2 saturation that can normalize arterial O2 concentration ([O2]), VO2 max remains low. To determine why, seven lowlanders were studied at VO2 max (cycle ergometry) at sea level (SL), after 9-10 wk at 5,260 m [chronic hypoxia (CH)], and 6 mo later at SL in AH (FiO2 = 0.105) equivalent to 5,260 m. Pulmonary and leg indexes of O2 transport were measured in each condition. Both cardiac output and leg blood flow were reduced by approximately 15% in both AH and CH (P < 0.05). At maximal exercise, arterial [O2] in AH was 31% lower than at SL (P < 0.05), whereas in CH it was the same as at SL due to both polycythemia and hyperventilation. O2 extraction by the legs, however, remained at SL values in both AH and CH. Although at both SL and in AH, 76% of the cardiac output perfused the legs, in CH the legs received only 67%. Pulmonary VO2 max (4.1 +/- 0.3 l/min at SL) fell to 2.2 +/- 0.1 l/min in AH (P < 0.05) and was only 2.4 +/- 0.2 l/min in CH (P < 0.05). These data suggest that the failure to recover VO2 max after acclimatization despite normalization of arterial [O2] is explained by two circulatory effects of altitude: 1) failure of cardiac output to normalize and 2) preferential redistribution of cardiac output to nonexercising tissues. Oxygen transport from blood to muscle mitochondria, on the other hand, appears unaffected by CH.

Influencia de la temperatura en el comportamiento y color de Palaemon elegans (Rathke, 1837) (Crustacea, Decapoda)

[ES] El camarón de charco (Palaemon elegans) soporta altos rangos de temperatura, pero a medida que ésta baja (hasta 5 ºC) comienza a reducir sus movimientos hasta quedar completamente inmóvil, casi en letargo. A este cambio de comportamiento va unido un cambio en la coloración del cuerpo del animal, que pasa de ser completamente transparente con tonos vivos azules y amarillos a ser translúcido, con azules y amarillos mucho más pálidos

Hércules en la cultura popular contemporánea : una guía de cine, televisión, literatura de masas e internet (1900-2012), y su aprovechamiento en la clase de Español LE/L2

Facultad de Traducción e Interpretación

Comportamiento de apoyo social en especies territoriales: "Parablennius parvicornis" (Valenciennes, 1836) y "Mauligobius maderensis" (Valenciennes, 1837)

[ES] Se estudia el comportamiento de apoyo social entre individuos de dos especies de peces territoriales (Parablennius parvicornis y Mauligobius maderensis) ante una situación de estrés. Se observa que a medida que la densidad de individuos aumentaba el estrés respiratorio en los individuos disminuía.

La historiografía obrera italiana (1900-1981)

[ES] Este artículo estudia la evolución de la historiografía obrera italiana, que surge del marxismo y vinculada al PCI. Esta historiografía militante se caracterizó por la recopilación de fuentes documentales y el estudio del movimiento organizado, al tiempo que se debatía sobre cuestiones socio-económicas. En una segunda fase, a partir de 1956, la historiografía obrera italiana avanzó en pos de un mayor rigor científico, propósito que se concretó en una mayor apertura de los archivos y en la ampliación de la investigación a temáticas políticamente sensibles. Posteriormente, al calor de los cambios experimentados por el país en los años sesenta y setenta, y favorecida por los contactos con historiografías foráneas, la historiografía obrera italiana perdió progresivamente su carácter militante y se renovó con nuevas interrogantes y metodologías. [EN] This article looks at the evolution of labour historiography in Italy, a movement that emerged from Marxism and was linked to the PCI. This militant historiography was characterized by the compilation of documentary sources and the study of the organised movement, while general socio-economic issues were under discussion. The second phase, from 1956 onward, saw Italian labour historiography making advances in achieving greater thoroughness, involving the opening of more archives and expanding the research to politically sensitive issues. Subsequently, in the light of changes experienced by the country in the 1960s and 1970s, and thanks to foreign historiographies, the Italian labour historiography lost its militant nature in a progressive way and developed new queries and methodologies.