Letteratura scientifica selezionata sul tema "Talus amazonien"

PALSAR2 polarimetric distortion matrix is measured using corner reflectors deployed in the Amazonian forest. The Amazonian forest near the geomagnetic equator provides ideal sites for the assessment of L-band PALSAR2 antenna parameters, at free Faraday rotation. Corner reflectors (CRs) deployed at free Faraday rotation provide accurate estimation of antenna cross-talks in contrast to the biased measurements obtained with CRs deployed at significant Faraday rotation. The extended Freeman–Van Zyl calibration method introduced and validated for ALOS-PALSAR calibration is used for the assessment of PALSAR-2 calibration parameters. Six datasets collected over the Amazonian rainforests (with CRs) are used to assess PALSAR-2 distortion matrix for five beams (FP6-3 to FP6-7) with incidence angle varying from 25° to 40°. It is shown that the PALSAR2 antenna is highly isolated with very low cross-talks (lower than −40 dB). Finally, the impact of a significant Faraday rotation on antenna cross-talk measurements using CR is discussed.

One of the most persistent of all New World dreams, El Dorado has acquired new life over the last two decades throughout much of the Amazon Basin. Many of the same golden visions that led Orellana and his men to plunge ahead down an “ocean-river” in the sixteenth century continue to prompt large numbers of people in Ecuador, Colombia, Venezuela, Peru, and, above all, Brazil to leave their families and set out for makeshift mining camps to seek their fortunes amidst a sea of mud. This discussion focuses on representations of gold miners or garimpeiros by themselves and others. I argue that although miners unquestionably draw on a much larger oral tradition, their stories stand apart from those told by a more general population in their tendency to portray gold as an active, female agent and in their relative lack of interest in clear-cut morals. In addition, while the vision of nature and natural forces as female and the fixation on violence as a (if not the) key element of life in the garimpo would appear to corroborate precisely those images of miners that reach a national and international public, this surface agreement cloaks important underlying differences that underscore the fundamental multiplicity of metaphor.

Abstract This article presents some results of a long-term research project on the Iskonawa, a Peruvian Amazon community that until recently many specialists considered gone. The few living speakers hold a world of knowledge and oral tradition that a team of Peruvian researchers has been collecting since 2010. Some Iskonawa myths of origin and survival tell us about their relationship with nature, their use of animals and plants, and a bleak future of deforestation, contamination, drug trafficking, and other crimes. In some of these narratives, it is possible to find alternative views of nature and the world in general that challenge the Western and neoliberal approach to the Amazonian basin.

Esta investigación tiene como objetivo evaluar si las narrativas de que la implementación de Centrales Hidroeléctricas son el mejor camino para el desarrollo y una fuente de energía limpia y sostenible representa una estrategia para la imposición de un nuevo ciclo de explotación de la región amazónica, caracterizado por imponer altos costos socioambientales para la región. Con este fin, se discute la resignificación otorgada a los ríos y a la región amazónica en los planes del gobierno brasileño, especialmente a partir de la Operación Amazonia, desde la década de 1960. La Amazonia recibió especial atención del gobierno brasileño en la expansión de las fuentes hidroeléctricas en el sector energético brasileño, sin que hubiera ninguna preocupación con relación a los impactos socioambientales de tales proyectos. Las narrativas y documentos oficiales, sin demostrar veracidad, impusieron la expansión hidroeléctrica como la única forma para el desarrollo del país, lo que hizo posible la construcción de varias centrales hidroeléctricas en la Amazonia, con resultados trágicos para los pueblos y comunidades tradicionales. Para obtener tales consideraciones, se realizó una investigación bibliográfica y documental.

Este estudio presenta la composición, diversidad, abundancia y distribución geográfica y altitudinal de las especies del género Rhagovelia en la cuenca alta de Río Putumayo, Piedemonte sur de la Amazonia, departamento de Putumayo. Las estaciones de muestreo fueron establecidas en el rango altitudinal entre los 160 a 590 m snm, comprendido entre las localidades de Mocoa a Puerto Asis. Las muestras fueron colectadas en Junio y Noviembre de 2015, usando redes entomológicas. En total se presentan siete especies del género Rhagovelia, pertenecientes a los grupos bisignata y robusta; se describe la forma macróptera de la especie Rhagovelia longipes Gould, 1931. Se amplió el rango geográfico para la mayoría de las especies y se preciso el rango altitudinal de tales especies en el pidemonte de la Amazonia. Para cada especie también se caracterizó el hábitat a través de los paramentros físico-químicos del agua donde se recolectaron los especímenes.

A partir del análisis de cuatro libros testimoniales del secuestro de personas del grupo de “los canjeables” se evidencia que la Amazonia es representada a través de dos de las imágenes recurrentes que sobre esta región se han emitido en la historia de su contacto con Occidente: un paraíso abudante en recursos naturales y un infierno verde. La primera de las imágenes responde al imaginario conservacionista de la naturaleza conceptualizada como medio ambiente, en el marco del discurso de la posibilidad de una crisis climática inminente. La segunda, que es la percepción de la Amazonia como un infierno que consume a quien cae en sus redes, se circunscribe a los espacios construidos por la guerrilla y que fueron experimentados con ellos. La representación de la Amazonia está en conexión con el drama que viven las víctimas del secuestro, cuya experiencia individual también se vive de manera grupal, así como transita desde las relaciones entre los seres humanos y de éstos con la naturaleza. Por tanto, la sensación apabulladora del dosel oscuro de la selva y de sus minúsculos, pero incómodos animales, se resalta como escenario del sufrimiento emocional y físico de los cautivos. Así, los libros analizados despliegan un discurso conformado por imaginarios sobre la Amazonia que se pliegan al proyecto social específico delos sectores más influyentes en los campos de la política y la economía en el país. Una de sus narrativas establece que tales territorios están totalmente disponibles para la inversión de capital luego de que sean liberados del dominio de los grupos rebeldes.

La marée interne est un phénomène complexe généré par l'interaction entre les marées de surface avec la topographie marine (monts sous-marins, pentes continentales, dorsales) dans un contexte d'océan stratifié. La dissipation de l'énergie associée à la marée interne engendre un intense mélange vertical qui influence la température de l'océan sur toute la colonne d'eau jusqu'en surface, ce qui a un impact significatif pour circulation thermohaline, pour le mélange profond, et pour la convection nuageuse, concernant le mélange plus en surface. L'ensemble des deux (marée interne et de surface) a donc un impact important sur le climat. Ce mélange influence également les concentrations en nutriments, et par ricochet la production primaire et la distribution des organismes marins. Ces divers impacts sont assez documentés dans certaines régions océaniques grâce aux données in situ et à la modélisation numérique. Mais la question de l'impact de la marée interne sur la structure de la température et des nutriments reste encore ouverte concernant la région au large de l'embouchure de l'Amazone, qui est ma zone d'étude. L'objectif premier de ma thèse, qui est technique, est de fournir une base de données de simulations numériques permettant d'étudier la dynamique de la marée interne et de son impact sur le milieu physique et la biogéochimie marine au large de l'embouchure de l'Amazone. Le second objectif, qui est scientifique, est d'utiliser ces simulations pour analyser l'impact de la marée interne sur la structure de la température et sa variabilité dans le temps. Durant ma thèse, j'ai participé à la mise en place de deux configurations du modèle NEMO dédiées à l'étude des ondes internes de marée. L'une est physique et baptisée "AMAZON36", et l'autre est couplée physique-biogéochimie avec le modèle PISCES et baptisée "AMAZON36-BIO". Ensuite, j'ai réalisé, pour chacune des deux configurations, des simulations jumelles (avec et sans forçage de marée) sur plusieurs années, 2007-2016 et 2013-2016 pour AMAZON36 et AMAZON36 -BIO, respectivement. Dans la suite de la thèse, nous avons utilisé les simulations de la configuration AMAZON36 pour montrer comment au large de l'embouchure de l'Amazone, les ondes internes de marée entrainent un refroidissement significatif de la SST qui induit une augmentation des flux net de chaleur entre l'océan et l'atmosphère sus-jacente. Les ondes internes de marée induisent également un refroidissement de la température sur la verticale à l'intérieur de l'océan, dans la couche de mélange et au-dessus de la thermocline, et un refroidissement en dessous jusqu'à plusieurs centaines de mètres. Nous avons aussi montré que c'est par le mélange vertical que les ondes internes de marée impactent la température sur toute la verticale. Dans la suite, nous avons utilisé ces simulations et des observations satellites de la température de surface de la mer (SST) pour analyser variabilité temporelle de cet impact sur la température aux fréquences semi-diurnes et bimensuelle depuis la surface jusqu'à l'intérieur de la colonne d'eau. Il apparait clairement que les ondes internes dans leurs zones de dissipation sur le talus et au large, entrainent de fortes fluctuations de température à haute fréquence pouvant atteindre plusieurs degrés Celsius, et un peu moins à l'échelle bimensuelle. Les travaux de ma thèse permettent ainsi (i) de mieux appréhender les mécanismes et les échelles temporelles d'action de la marée interne sur la température au large de l'embouchure de l'Amazone, et (ii) posent une base solide, en termes de réalisation de simulations numériques, pour l'analyse de l'impact de la marée interne sur la biogéochimie dans cette région
Internal tides (IT) are a complex phenomenon generated by the interaction between surface tides and marine topography (seamounts, continental slopes, ridges) in a stratified ocean. The dissipation of IT's energy generates an intense vertical mixing that influences the temperature of the ocean over the entire water column down to the surface, which has a significant impact on the thermohaline circulation, for the deep mixing, and for the cloud convection, concerning the mixing close to the surface. Together, they both (internal and surface tides) have a significant impact on the climate. This mixing also influences nutrient concentrations, and in turn the primary production and distribution of marine organisms. These various impacts are well documented in some ocean regions thanks to in situ data and numerical modelling. But the question of the impact of ITs on the structure of temperature and nutrients is still open regarding the region off the mouth of the Amazon, which is my study area. The primary objective of my thesis, which is technical, is to provide a database of numerical simulations to study the dynamics of ITs and their impact on the physical environment and marine biogeochemistry off the mouth of the Amazon. The second objective, which is scientific, is to use these simulations to analyze the impact of ITs on the temperature structure and its variability over time. During my thesis, I participated in the implementation of two configurations of the NEMO model dedicated to the study of ITs. One is physical and called "AMAZON36" and the other is coupled with the PISCES model and is called "AMAZON36 -BIO". Then, for each of the two configurations, I performed twin simulations (with and without tidal forcing) over several years, 2007-2016 and 2013-2016 for AMAZON36 and AMAZON36 -BIO, respectively. In the rest of the thesis, we used simulations of the AMAZON36 configuration to show how off the mouth of the Amazon, the mixing induced by the dissipation of ITs impacts the SST, the net heat flux between the ocean and the overlying atmosphere, the temperature on the vertical. And finally, what are the processes by which the internal tides act. Subsequently, we used these simulations and satellite observations of sea surface temperature (SST) to analyze the temporal variability of this impact on temperature at semi-diurnal and fortnightly frequencies from the surface to the interior of the water column. My thesis has allowed (i) to better understand the mechanisms and the temporal scales of IT's actions on the temperature off the mouth of the Amazon, and (ii) lay a solid basis for the analysis of the impact of the internal tides on biogeochemistry in this region

This chapter mentions how Ruggero Deodato'sCannibal Holocaust was speculated to have inspired the film The Blair Witch Project merely on account of its use of found footage. It talks about Eli Roth's The Green Inferno, which shares its title with the moniker given to Cannibal Holocaust's Amazonian locale. It also points out how Roth gleefully condemns what he exploits and how his 'message' could be interpreted as similarly problematic as Cannibal Holocaust. The chapter discusses Cannibal Holocaust's extreme imagery that initiates an argument about censorship. It analyses the confrontational aspect of Cannibal Holocaust that comes from the audience's own spectatorship.

So, it turns out those many, many Atlantises were all too often riven with misogyny and racism. Those Amazonian tales were frequently vehicles for male fears of powerful capable women seeking rights and recognition. The Greek gods were almost always aliens, immeasurably powerful yet destined to fall. Time travel to Greece and Rome often served to demonstrate how much better ‘we’ are than ‘them’, or conversely (sometimes simultaneously) how much we ‘owe’ them. The iconoclasts of the New Wave literature and the subversive filmmakers of the 1970s were endlessly fascinating, as are the current game developers adapting ancient materials to new and exciting results. Here were glimmers of progressive politics or nuanced representation with classics at their core – elsewhere was a return to the reverence not even of art or culture, but the perceived superiority of manly men from antiquity to support regressive ideologies....