Insights into historical drainage evolution based on the phylogeography of the chevron snakehead fish (Channa striata) in the Mekong Basin

1. The phylogeography of freshwater taxa is often integrally linked with landscape changes such as drainage re-alignments that may present the only avenue for historical dispersal for these taxa. Classical models of gene flow do not account for landscape changes and so are of little use in predicting phylogeography in geologically young freshwater landscapes. When the history of drainage formation is unknown, phylogeographical predictions can be based on current freshwater landscape structure, proposed historical drainage geomorphology, or from phylogeographical patterns of co-distributed taxa. 2. This study describes the population structure of a sedentary freshwater fish, the chevron snakehead (Channa striata), across two river drainages on the Indochinese Peninsula. The phylogeographical pattern recovered for C. striata was tested against seven hypotheses based on contemporary landscape structure, proposed history and phylogeographical patterns of codistributed taxa. 3. Consistent with the species ecology, analysis of mitochondrial and microsatellite loci revealed very high differentiation among all sampled sites. A strong signature of historical population subdivision was also revealed within the contemporary Mekong River Basin (MRB). Of the seven phylogeographical hypotheses tested, patterns of co-distributed taxa proved to be the most adequate for describing the phylogeography of C. striata. 4. Results shed new light on SE Asian drainage evolution, indicating that the Middle MRB probably evolved via amalgamation of at least three historically independent drainage sections and in particular that the Mekong River section centred around the northern Khorat Plateau in NE Thailand was probably isolated from the greater Mekong for an extensive period of evolutionary time. In contrast, C. striata populations in the Lower MRB do not show a phylogeographical signature of evolution in historically isolated drainage lines, suggesting drainage amalgamation has been less important for river landscape formation in this region.

A single-Stream jet noise prediction model for a family of chevron nozzles

This study develops a single-stream jet noise prediction model for a family of chevron nozzles. An original equation is proposed for the fourth-order space-time cross-correlations. They are expressed in flow parameters such as streamwise circulation and turbulent kinetic energy. The cross-correlations based on a Reynolds Averaged Navier-Stokes (RANS) flowfield showed a good agreement with those based on a Large Eddy Simulation (LES) flowfield. This proves that the proposed equation describes the cross-correlations accurately. With this novel source description, there is an excellent agreement between our model's far-field noise predictions and measurements1 for a wide range of frequencies and radiation angles. Our model captures the spectral shape, amplitude and peak frequency very well. This establishes that our model holds good for a family of chevron nozzles. As our model provides quick and accurate predictions, a parametric study was performed to understand the effects of a chevron nozzle geometry on jet noise and thrust loss. Chevron penetration is the underpinning factor for jet noise reduction. The reduction of jet noise per unit thrust loss decreases linearly with chevron penetration. The number of chevrons also has a considerable effect on jet noise.

Caso Chevron-Texaco: cuando los pueblos toman la palabra

Este libro analiza las estrategias de comunicación y movilización desarrolladas por los pobladores e indígenas de la Amazonía ecuatoriana en su lucha por la justicia ambiental frente al desastre causado por la Chevron- Texaco durante su operación entre 1964 y 1990. La sentencia emitida por la Corte de Justicia de Sucumbíos en febrero de 2011 reconoce la responsabilidad de la empresa estadounidense por los daños y la negligencia con la que operó, ordenando el pago de una suma millonaria a los pobladores de la Amazonía. En la primera parte, se enmarca la relación entre la explotación petrolera, la globalización neoliberal y el “desarrollo”; se presentan los impactos socioambientales de la explotación petrolera, y se examina el rol de la empresa, del Estado y de los actores sociales. En la segunda parte, se analiza el discurso hegemónico de Chevron-Texaco -dirigido sobre todo a negar la contaminación y deslegitimar a las organizaciones sociales y al Estado ecuatoriano-, y se abordan las estrategias discursivas y comunicacionales desarrolladas por la Asamblea de Afectados y el Frente de Defensa de la Amazonía -cuyo objetivo era simplemente mostrar la realidad-. En la tercera parte, se estudia cómo el trabajo en red con organizaciones ecologistas nacionales y transnacionales del Norte y del Sur potencia la movilización social y la lucha de los pobladores de la Amazonía. Y la autora concluye que esta experiencia constituye un ejemplo y un aporte para quienes día a día trabajan por alcanzar la justicia global.

El derecho a la reparación de las comunidades afectadas por Chevron-Texaco

Entre 1964 y 1990 la compañía petrolera Texaco causó un grave desastre ambiental y humano en el nororiente del Ecuador, por lo que las comunidades indígenas y campesinas presentaron en 1993 una acción en su contra en las cortes de Nueva York. Durante casi 10 años la petrolera luchó para que estas cortes desestimen la causa y la envíen al Ecuador, alegando que era esta la jurisdicción donde debía resolverse el caso. En 2002 las cortes norteamericanas desestimaron la causa por forum non conveniens y en 2003 se presentó una acción contra Chevron Corporation (en adelante Chevron), que en 2001 se había fusionado con Texaco, ante la Corte Provincial de Sucumbíos. Después de 56 inspecciones judiciales, 118 informes periciales, cerca de 64.000 resultados de laboratorio y alrededor de 215.000 páginas de expediente, el 14 de febrero de 2011 el Presidente de la Corte Provincial de Sucumbíos emitió sentencia condenatoria contra Chevron, estableciendo la obligación de pago por medidas de reparación: principales, complementarias y de mitigación que suman un total de US $ 19.021’552.000

A new Amphisbaena with chevron-shaped anterior body annuli from state of Pernambuco: Brazil (Squamata: Amphisbaenidae)

A new species of Amphisbaena is described from Fazenda Porto Seguro, municipality of Buique, state of Pernambuco, in the Caatingas of northeastern Brazil based on four specimens. The new species is a small and slender amphisbaenian with four precloacal pores, 333-337 body annuli, 22-23 tail annuli with discrete evidence of an autotomic site on the 10-12 tail annuli, and 14 dorsal and 17-18 ventral segments per annuli at midbody. The high number of body annuli, the presence of chevron-shaped anterior body annuli, and the fusion of frontal scales distinguish Amphisbaena supernumeraria sp. nov. from its congeners.