7,428 research outputs found
La identidad como utopía en América Latina. Palabra y movilización de los pueblos indígenas
_Se reivindica la idea de utopía como proyecto político de emancipación que permite establecer una tensión entre lo que es y lo que se quiere ser, ejemplificándolo con el caso del neozapatismo chiapaneco
A two-layer shallow water model for bedload sediment transport: convergence to Saint-Venant-Exner model
A two-layer shallow water type model is proposed to describe bedload sediment
transport. The upper layer is filled by water and the lower one by sediment.
The key point falls on the definition of the friction laws between the two
layers, which are a generalization of those introduced in Fern\'andez-Nieto et
al. (ESAIM: M2AN, 51:115-145, 2017). This definition allows to apply properly
the two-layer shallow water model for the case of intense and slow bedload
sediment transport. Moreover, we prove that the two-layer model converges to a
Saint-Venant-Exner system (SVE) including gravitational effects when the ratio
between the hydrodynamic and morphodynamic time scales is small. The SVE with
gravitational effects is a degenerated nonlinear parabolic system. This means
that its numerical approximation is very expensive from a computational point
of view, see for example T. Morales de Luna et al. (J. Sci. Comp., 48(1):
258-273, 2011). In this work, gravitational effects are introduced into the
two-layer system without such extra computational cost. Finally, we also
consider a generalization of the model that includes a non-hydrostatic pressure
correction for the fluid layer and the boundary condition at the sediment
surface. Numerical tests show that the model provides promising results and
behave well in low transport rate regimes as well as in many other situations
La identidad como utopía en América Latina. Palabra y movilización de los pueblos indígenas
_Se reivindica la idea de utopía como proyecto político de emancipación que permite establecer una tensión entre lo que es y lo que se quiere ser, ejemplificándolo con el caso del neozapatismo chiapaneco
Morphometric differences in two calanoid sibling species, Boeckella gracilipes and B. titicacae (Crustacea, Copepoda)
Núcleo de Estudios Ambientales, Universidad Católica de TemucoCalanoid copepods are abundant in South American inland waters and include widespread species, such as Boeckella gracilipes (Daday, 1902), which occurs from the Ecuador to Tierra del Fuego Island. This species occurs under various environmental conditions, and is found in oligotrophic lakes in Patagonia (39-54°S) and in shallow mountain lakes north of 39°S. The aim of the present study is to conduct a morphometric comparison of male specimens of B. titicacae collected in Titicaca and B. gracilipes collected in Riñihue lakes, with a third population of B. gracilipes collected in shallow ponds in Salar de Surire. Titicaca and Riñihue lakes are stable environments, whereas Salar de Surire is an extreme environment. These ponds present an extreme environment due to high exposure to solar radiation and high salinity levels. The results of the study revealed differences among the three populations. These results agree well with systematic descriptions in the literature on differences between the populations of Titicaca and Riñihue lakes, and population of Salar de Surire differs slightly from the other two populations. It is probable that the differences between the population of Salar de Surire and the other two populations result from the extreme environment in Salar de Surire. High exposure to solar radiation, high salinity and extreme variations in temperature enhance genetic variations that are consequently expressed in morphology.Los copépodos calanoideos son abundantes en aguas continentales sudamericanas e incluyen especies de amplia distribución geográfica como Boeckella gracilipes (Daday, 1902) que se encuentra desde Ecuador hasta la isla de Tierra del Fuego. Esta especie vive bajo varias condiciones ambientales, y se encuentra en lagos oligotróficos en la Patagonia (39-54°S) y en lagunas superficiales de montaña al norte de los 39°S. El objetivo del presente trabajo es realizar un estudio comparativo morfométrico de machos de B. titicacae colectado en el lago Titicaca y B. gracilipes colectado en el lago Riñihue, ambos son ambientes estables, con una tercera población colectada en lagunas superficiales en el Salar de Surire. Estas lagunas tienen condiciones ambientales extremas debido a alta exposición a la radiación solar y altos niveles de salinidad. Los resultados del presente estudio encontraron diferencias entre las tres poblaciones. Estos resultados concordarían con las descripciones sistemáticas en la literatura sobre las diferencias de las poblaciones de los lagos Titicaca y Riñihue, y la población del salar de Surire tuvo leves diferencias respecto a las dos poblaciones anteriores. Es probable que las diferencias entre la población del Salar de Surire y las otras dos se deban a alta exposición a la radiación solar, salinidad y condiciones extremas de temperatura que acelera las diferencias genéticas las que se expresan en diferencias morfológicas
Richness and Distribution of Zooplanktonic Crustacean Species in Chilean Andes Mountains and Southern Patagonia Shallow Ponds
The lacustrine ecosystems located in the Andes Mountains in the Atacama desert and in the Chilean
Southern Patagonia are characterized by their high levels of salinity, the zooplankton in these sites are characterized by a marked predominance of calanoid copepods at low or intermediate salinity levels, and at high salinity levels pratically only the genus Artemia is dominant. Data on levels of salinity and zooplanktonic
composition in both regions were collected in field work and from published data. Statistical analysis
showed a marked inverse association between salinity and species richness that was notoriously significant
for Andes Mountains (R = -0.8193; p = 0.0037), whereas for Southern Patagonia there were observed weakly
similar results, caused by lack of data between 5.0-15.0 g/l. Both zones observed calanoid dominance at low and moderate salinity levels between 3-51 g/l and 1-16 g/l for Andes Mountains and Southern Patagonia,
respectively, and Artemia genus was dominant at salinities above 100 g/l for Andes Mountains and 20
g/l for Southern Patagonia. Ecological and biogeographic effects, and comparison with zooplankton assemblages
of Australian saline lakes are discussed in the present study
Ecosistemas acuáticos de islas oceánicas de Chile: Conservación de microfauna endémica y el rol de especies exóticas en el control biológico de enfermedades tropicales
Carta al Edito
The Will as Conscious Desire: Kuno Fischer between Spinoza and Nietzsche
Es muy defendible afirmar que el volumen dedicado a Spinoza de la obra Historia de la filosofía moderna de Kuno Fischer es la mediación más importante –si bien no la única– para comprender la relación Spinoza-Nietzsche. A partir de la lectura de esta obra en 1881, Nietzsche reconoce a Spinoza como precursor e identifica una tendencia en común entre ambos: «hacer del conocimiento el afecto más potente». Los principales objetivos de este trabajo son destacar la exposición que Fischer lleva a cabo de algunos de los contenidos de la filosofía spinociana para poder valorar mejor su influencia en Nietzsche y resaltar la importancia que tiene tulo 22 de la edición de 1865, titulado «La voluntad humana», donde se interpreta la voluntad como deseo consciente, lo que tendrá sus consecuencias en la recepción de Nietzsche de la filosofía spinociana, además de permitir una discusión respecto del rol no siempre atendido de la voluntad en Spinoza.It can well be asserted that the volume dedicated to Spinoza in Kuno Fischer’s History of Modern Philosophy is the most important mediation – although not the only one – to comprehend the Spinoza-Nietzsche problem. From his reading in 1881 of this work, Nietzsche recognized Spinoza as a precursor and identified a common tendency between them: “to make knowledge the most potent affect”. The aim of this article is to emphasize Fischer’s exposition of some of the contents of Spinoza’s philosophy to better grasp its influence on Nietzsche and to highlight the importance of this forgotten classic in the history of philosophy. Specifically, chapter 22 from the 1865 edition – titled “The human will” – shall be considered, where will is construed as conscious desire. This has important consequences on Nietzsche’s reception of Spinozian philosophy. Moreover, it can also allow a much richer discussion of the not always pondered role of will in Spinoza
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