978 resultados para Irregular Polygon


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Colombia es el epicentro de una situación humanitaria y de derechos humanos crítica como consecuencia de un conflicto armado anacrónico que persiste sin solución militar posible, pero que continúa sin salida política y negociada a la vista. Las migraciones forzadas, que se expresan en desplazados internos, refugiados y formas de movilidad asociadas a la crisis económica, van más allá de las fronteras y representan una expansión de las consecuencias de una guerra irregular en territorios de países vecinos. Este artículo se limita a describir los cambios políticos que siguieron a la ruptura del proceso de paz, a ofrecer otra lectura del Plan Colombia y sus consecuencias específicas en el campo humanitario, a visibilizar las migraciones forzadas y el refugio y a proponer alternativa de acción conjunta y concertada en la región.

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El trabajo doméstico representa en la actualidad el mayor sector laboral para mujeres migrantes en todo el mundo, encontrándose también en Europa en franca expansión. Esto tiene que ver, entre otras razones, con importantes procesos sociales contemporáneos como, por ejemplo, la pregunta por el cuidado de anciano/as y enfermo/as, la compatibilidad de familia y empleo, el desmantelamiento del Estado de bienestar, las transformaciones demográficas así como también con la inmigración irregular y el trabajo informal que también están relacionados en forma directa o indirecta con preguntas de migración femenina. En lo que sigue se aborda esta interrelación de inclusión selectiva, y a la vez, de exclusión social. Primero me referiré al trabajo doméstico, sus características y problemáticas, a continuación, a la etnización y a la actual creciente demanda de trabajadoras domésticas migrantes. Para esto me baso en una investigación etnográfica de 14 meses sobre el proceso migratorio de empleadas domésticas ecuatorianas en España y Ecuador (2003-2004). La investigación incluye 87 entrevistas formales, un sinnúmero de conversaciones y entrevistas informales, así como observación participativa desarrollada tanto en Madrid como en Ecuador.

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El autor destaca la importancia en términos de compromisos políticos del Ecuador hacia una relación más estrecha con los países del Asia-Pacífico. El nuevo gobierno debe diseñar sus políticas en correspondencia con el escenario impuesto por la democracia liberal y el libre mercado, considerar incentivos para el desarrollo del comercio exterior y atracci6n de inversiones y tomar en cuenta la importancia de la competitividad interna. El sector privado debe revertir el comportamiento irregular de la exportaciones hacia algunos países de Asia-Pacífico y el Ministerio de Relaciones Exteriores fortalecer los lazos a nivel político-diplomático. Finalmente, el autor enfatiza la necesidad de una rápida modernización del sector público.

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Basado en fuentes primarias (epistolarios), el artículo ofrece una aproximación al proceso de formación de grupos armados irregulares, en la provincia de Manabí, a inicios del siglo XIX, como consecuencia de la disputa por el poder y el control del monopolio de la violencia, en el marco de construcción del nuevo régimen republicano. En esta región periférica del Estado central, la sociedad se torna violenta cuando es presionada tanto por el poder estatal, como por los caudillos locales que pretenden formar parte de las estructuras de poder local por medio del reclutamiento forzoso para engrosar las filas de milicias y grupos armados.

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Pone en discusión, desde una perspectiva crítica, el modo en que el discurso sobre la trata de personas se incorpora en la agenda política sobre migraciones en la región sudamericana y las implicancias políticas e ideológicas de esa incorporación. La trata de personas es abordada como “problema migratorio”, como una forma de “migración irregular, con la finalidad de securitizar el debate migratorio fomentando a los migrantes como “problema”.

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El presente trabajo tiene por finalidad visibilizar las brechas territoriales en el ingreso, la pobreza y la desigualdad de Ecuador en el período 2007 – 2013, el análisis se apoya en técnicas de estadística descriptiva para analizar la evolución del ingreso per cápita; gráficas de densidad Kernel para el análisis comparativo de la distribución del ingreso entre territorios; estadística inferencial aplicada a las variaciones de la incidencia de la pobreza y el coeficiente de Gini; y finalmente mediante técnicas econométricas del enfoque de crecimiento “pro-pobre” se identifica la relación entre los niveles de pobreza, el crecimiento del ingreso per cápita y la redistribución del ingreso en los territorios sub nacionales. Los resultados evidencian una estructura territorial sub nacional con marcadas brechas en los niveles y distribución del ingreso, con incidencia irregular de la pobreza a lo largo del país, no obstante durante el período 2007-2013 estas brechas tienden a reducirse, observándose además un crecimiento económico “pro pobre” en la mayoría de provincias entre el 2010 y 2013.

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Colombian foreign policy has gone through important transformations in its formulation and implementation. Through a Neoclassical Realist (NCR) analysis, this article discusses the domestic and systemic factors that have influenced the Foreign Policy Executive (FPE) in Colombia. It makes a historical journey through different presidential terms, ranging from the loss of Panama in 1903, to the adverse decision of the International Court of Justice (ICJ) in 2012, which stripped Bogotá of a significant portion of its Caribbean Sea. This analysis reveals problems in the formulation of Colombian foreign policy due to a weak foreign service, a complex relationship with the United States and the country’s internal conflict; it is argued that if these factors were to be reduced or disappear, a new form of foreign policy in the country would be facilitated in the twenty-first century.

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We used ground surveys to identify breeding habitat for Whimbrel (Numenius phaeopus) in the outer Mackenzie Delta, Northwest Territories, and to test the value of high-resolution IKONOS imagery for mapping additional breeding habitat in the Delta. During ground surveys, we found Whimbrel nests (n = 28) in extensive areas of wet-sedge low-centered polygon (LCP) habitat on two islands in the Delta (Taglu and Fish islands) in 2006 and 2007. Supervised classification using spectral analysis of IKONOS imagery successfully identified additional areas of wet-sedge habitat in the region. However, ground surveys to test this classification found that many areas of wet-sedge habitat had dense shrubs, no standing water, and/or lacked polygon structure and did not support breeding Whimbrel. Visual examination of the IKONOS imagery was necessary to determine which areas exhibited LCP structure. Much lower densities of nesting Whimbrel were also found in upland habitats near wetlands. We used habitat maps developed from a combination of methods, to perform scenario analyses to estimate the potential effects of the Mackenzie Gas Project on Whimbrel habitat. Assuming effective complete habitat loss within 20 m, 50 m, or 250 m of any infrastructure or pipeline, the currently proposed pipeline development would result in loss of 8%, 12%, or 30% of existing Whimbrel habitat. If subsidence were to occur, most Whimbrel habitat could become unsuitable. If the facility is developed, follow-up surveys will be required to test these models.

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We compared habitat features of Golden-winged Warbler (Vermivora chrysoptera) territories in the presence and absence of the Blue-winged Warbler (V. cyanoptera) on reclaimed coal mines in southeastern Kentucky, USA. Our objective was to determine whether there are species specific differences in habitat that can be manipulated to encourage population persistence of the Golden-winged Warbler. When compared with Blue-winged Warblers, Golden-winged Warblers established territories at higher elevations and with greater percentages of grass and canopy cover. Mean territory size (minimum convex polygon) was 1.3 ha (se = 0.1) for Golden-winged Warbler in absence of Blue-winged Warbler, 1.7 ha (se = 0.3) for Golden-winged Warbler coexisting with Blue-winged Warbler, and 2.1 ha (se = 0.3) for Blue-winged Warbler. Territory overlap occurred within and between species (18 of n = 73 territories, 24.7%). All Golden-winged and Blue-winged Warblers established territories that included an edge between reclaimed mine land and mature forest, as opposed to establishing territories in open grassland/shrubland habitat. The mean distance territories extended from a forest edge was 28.0 m (se = 3.8) for Golden-winged Warbler in absence of Blue-winged Warbler, 44.7 m (se = 5.7) for Golden-winged Warbler coexisting with Blue-winged Warbler, and 33.1 m (se = 6.1) for Blue-winged Warbler. Neither territory size nor distances to forest edges differed significantly between Golden-winged Warbler in presence or absence of Blue-winged Warbler. According to Monte Carlo analyses, orchardgrass (Dactylis glomerata), green ash (Fraxinus pennsylvanica) seedlings and saplings, and black locust (Robinia pseudoacacia) saplings were indicative of sites with only Golden-winged Warblers. Sericea lespedeza, goldenrod (Solidago spp.), clematis vine (Clematis spp.), and blackberry (Rubus spp.) were indicative of sites where both species occurred. Our findings complement recent genetic studies and add another factor for examining Golden-winged Warbler population decline. Further, information from our study will aid land managers in manipulating habitat for the Golden-winged Warbler.

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Integrations of a fully-coupled climate model with and without flux adjustments in the equatorial oceans are performed under 2×CO2 conditions to explore in more detail the impact of increased greenhouse gas forcing on the monsoon-ENSO system. When flux adjustments are used to correct some systematic model biases, ENSO behaviour in the modelled future climate features distinct irregular and periodic (biennial) regimes. Comparison with the observed record yields some consistency with ENSO modes primarily based on air-sea interaction and those dependent on basinwide ocean wave dynamics. Simple theory is also used to draw analogies between the regimes and irregular (stochastically forced) and self-excited oscillations respectively. Periodic behaviour is also found in the Asian-Australian monsoon system, part of an overall biennial tendency of the model under these conditions related to strong monsoon forcing and increased coupling between the Indian and Pacific Oceans. The tropospheric biennial oscillation (TBO) thus serves as a useful descriptor for the coupled monsoon-ENSO system in this case. The presence of obvious regime changes in the monsoon-ENSO system on interdecadal timescales, when using flux adjustments, suggests there may be greater uncertainty in projections of future climate, although further modelling studies are required to confirm the realism and cause of such changes.

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We consider the problem of scattering of a time-harmonic acoustic incident plane wave by a sound soft convex polygon. For standard boundary or finite element methods, with a piecewise polynomial approximation space, the computational cost required to achieve a prescribed level of accuracy grows linearly with respect to the frequency of the incident wave. Recently Chandler–Wilde and Langdon proposed a novel Galerkin boundary element method for this problem for which, by incorporating the products of plane wave basis functions with piecewise polynomials supported on a graded mesh into the approximation space, they were able to demonstrate that the number of degrees of freedom required to achieve a prescribed level of accuracy grows only logarithmically with respect to the frequency. Here we propose a related collocation method, using the same approximation space, for which we demonstrate via numerical experiments a convergence rate identical to that achieved with the Galerkin scheme, but with a substantially reduced computational cost.

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In this paper we consider the problem of time-harmonic acoustic scattering in two dimensions by convex polygons. Standard boundary or finite element methods for acoustic scattering problems have a computational cost that grows at least linearly as a function of the frequency of the incident wave. Here we present a novel Galerkin boundary element method, which uses an approximation space consisting of the products of plane waves with piecewise polynomials supported on a graded mesh, with smaller elements closer to the corners of the polygon. We prove that the best approximation from the approximation space requires a number of degrees of freedom to achieve a prescribed level of accuracy that grows only logarithmically as a function of the frequency. Numerical results demonstrate the same logarithmic dependence on the frequency for the Galerkin method solution. Our boundary element method is a discretization of a well-known second kind combined-layer-potential integral equation. We provide a proof that this equation and its adjoint are well-posed and equivalent to the boundary value problem in a Sobolev space setting for general Lipschitz domains.

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Mega-scale glacial lineations (MSGLs) are longitudinally aligned corrugations (ridge-groove structures 6-100 km long) in sediment produced subglacially. They are indicators of fast flow and a common signature of ice-stream beds. We develop a qualitative theory that accounts for their formation, and use numerical modelling, and observations of ice-stream beds to provide supporting evidence. Ice in contact with a rough (scale of 10-10(3) m) bedrock surface will mimic the form of the bed. Because of flow acceleration and convergence in ice-stream onset zones, the ice-base roughness elements experience transverse strain, transforming them from irregular bumps into longitudinally aligned keels of ice protruding downwards. Where such keels slide across a soft sedimentary bed, they plough through the sediments, carving elongate grooves, and deforming material up into intervening ridges. This explains MSGLs and has important implications for ice-stream mechanics. Groove ploughing provides the means to acquire new lubricating sediment and to transport large volumes of it downstream. Keels may provide basal drag in the force budget of ice streams, thereby playing a role in flow regulation and stability We speculate that groove ploughing permits significant ice-stream widening, thus facilitating high-magnitude ice discharge.

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A spatangoid-produced ichnofabric is described from the Miocene Bateig Limestone, SE Spain. This ichnofabric is characterized by the dominant presence of large meniscate burrows (Bichordites) produced by irregular echinoids. This constitutes an unusual mode of occurrence for spatangoid bioturbation, as their traces are most typically preserved in bases and tops of sandstone event beds. In fact, despite their important role as burrowers in modern settings (that can be extended back to the Early Cretaceous based on their body fossil record), spatangoid trace fossils (Scolicia and Bichordites) are comparatively rare. Several factors play an important role in their preservation: mechanism of burrowing, sediment characteristics, early diagenesis and presence/absence of deep-tier burrowers. Spatangoid-produced ichnofabrics, such as those from the Bateig Limestone, characterize depositional settings with intermittent deposition of event beds where there is an absence of deeper-tier bioturbation. (C) 2008 Elsevier B.V. All rights reserved

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Given the non-monotonic form of the radiocarbon calibration curve, the precision of single C-14 dates on the calendar timescale will always be limited. One way around this limitation is through comparison of time-series, which should exhibit the same irregular patterning as the calibration curve. This approach can be employed most directly in the case of wood samples with many years growth present (but not able to be dated by dendrochronology), where the tree-ring series of unknown date can be compared against the similarly constructed C-14 calibration curve built from known-age wood. This process of curve-fitting has come to be called "wiggle-matching." In this paper, we look at the requirements for getting good precision by this method: sequence length, sampling frequency, and measurement precision. We also look at 3 case studies: one a piece of wood which has been independently dendrochronologically dated, and two others of unknown age relating to archaeological activity at Silchester, UK (Roman) and Miletos, Anatolia (relating to the volcanic eruption at Thera).