1000 resultados para TURISMO - INVESTIGACIONES - ARGENTINA
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Monográfico con el título: 'Profesorado principiante e inserción profesional a la docencia'. Investigación original con el título: 'De estudiantes a profesores: primeros desempeños profesionales en secundarios del conurbano bonaerense'. Resumen basado en el de la publicación
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Resumen basado en el de la publicaci??n.
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Radon levels in two old mines in San Luis, Argentina, are reported and analyzed. The radiation dose and environmental health risk of (222)Rn concentrations to both guides and visitors were estimated. CR-39 nuclear track detectors were used for this purpose. The values for the (222)Rn concentration at each monitoring site ranged from 0.43 +/- 0.04 to 1.48 +/- 0.12 kBq m(-3) in the Los Cndores wolfram mine and from 1.8 +/- 0.1 to 6.0 +/- 0.5 kBq center dot m(-3) in the La Carolina gold mine, indicating that, in this mine, the radon levels exceed up to four times the action level of 1.5 kBq m(-3) recommended by the International Commission on Radiological Protection. The patterns of the radon transport process revealed that the La Carolina gold mine can be interpreted as a gas confined into a single tube with constant cross-section and air velocity. Patterns of radon activity, taking into account the chimney-effect winds, were used to detect tributary currents of air from shafts or larger fissures along the main adit of the Los Cndores mine, showing that radon can be used as an important tracer of tributary air currents stream out from fissures and smaller voids in the rock of the mine.
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Radon and gamma radiation level measurements were carried out inside the La Carolina mine, one of the oldest gold mining camps of southern South America, which is open for touristic visits nowadays. CR-39 track-etch detectors and thermoluminescent dosimeters of natural CaF(2) and LiF TLD-100 were exposed at 14 points along the mine tunnels in order to estimate the mean (222)Rn concentration and the ambient dose equivalent during the summer season (November 2008 to February 2009). The values for the (222)Rn concentration at each monitoring site ranged from 1.8 +/- 0.1 kBq m(-3) to 6.0 +/- 0.5 kBq m(-3), with a mean value of 4.8 kBq m(-3), indicating that these measurements exceed in about three times the upper action level recommended by ICRP for workplaces. The correlations between radon and gamma radiation levels inside the mine were also investigated. Effective doses due to (222)Rn and gamma rays inside the mine were determined, resulting in negligible values to tourists. Considering the effective dose to the mine tourist guides, values exceeding 20 mSv of internal contribution to the effective doses can be reached, depending on the number of working hours inside the mine. (C) 2009 Elsevier Ltd. All rights reserved.
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New petrologic, thermobarometric and U-Pb monazite geochronologic information allowed to resolve the metamorphic evolution of a high temperature mid-crustal segment of an ancient subduction-related orogen. The EI Portezuelo Metamorphic-Igneous Complex, in the northern Sierras Pampeanas, is mainly composed of migmatites that evolved from amphibolite to granulite metamorphic facies, reaching thermal peak conditions of 670-820 degrees C and 4.5-5.3 kbar. The petrographic study combined with conventional and pseudosection thermobarometry led to deducing a short prograde metamorphic evolution within migmatite blocks. The garnet-absent migmatites represent amphibolite-facies rocks, whereas the cordierite-garnet-K-feldspar-sillimanite migmatites represent higher metamorphic grade rocks. U-Pb geochronology on monazite grains within leucosome record the time of migmatization between approximate to 477 and 470 Ma. Thus, the El Portezuelo Metamorphic-Igneous Complex is an example of exhumed Early Ordovician anatectic middle crust of the Famatinian mobile belt. Homogeneous exposure of similar paleo-depths throughout the Famatinian back-arc and isobaric cooling paths suggest slow exhumation and consequent longstanding crustal residence at high temperatures. High thermal gradients uniformly distributed in the Famatinian back-arc can be explained by shallow convection of a low-viscosity asthenosphere promoted by subducting-slab dehydration. (C) 2011 Elsevier Ltd. All rights reserved.
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We studied the P-T-t evolution of a mid-crustal igneous-metamorphic segment of the Famatinian Belt in the eastern sector of the Sierra de Velasco during its exhumation to the upper crust. Thermobarometric and geochronological methods combined with field observations permit us to distinguish three tectonic levels. The deepest Level I is represented by metasedimentary xenoliths and characterized by prograde isobaric heating at 20-25 km depth. Early/Middle Ordovician granites that contain xenoliths of Level I intruded in the shallower Level II. The latter is characterized by migmatization coeval with granitic intrusions and a retrograde isobaric cooling P-T path at 14-18 km depth. Level II was exhumed to the shallowest supracrustal Level III, where it was intruded by cordierite-bearing granites during the Middle/Late Ordovician and its host-rock was locally affected by high temperature-low pressure HT/LP metamorphism at 8-10 km depth. Level III was eventually intruded by Early Carboniferous granites after long-term slow exhumation to 6-7 km depth. Early/Middle Ordovician exhumation of Level II to Level III (Exhumation Period I,0.25-0.78 mm/yr) was faster than exhumation of Level III from the Middle/Late Ordovician to the Lower Carboniferous (Exhumation Period II, 0.01-0.09 mm/yr). Slow exhumation rates and the lack of regional evidence of tectonic exhumation suggest that erosion was the main exhumation mechanism of the Famatinian Belt. Widespread slow exhumation associated with crustal thickening under a HT regime suggests that the Famatinian Belt represents the middle crust of an ancient Altiplano-Puna-like orogen. This thermally weakened over-thickened Famatinian crust was slowly exhumed mainly by erosion during similar to 180 Myr. (C) 2010 International Association for Gondwana Research. Published by Elsevier B.V. All rights reserved.
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The whole Valle Fertil-La Huerta section appears as a calc-alkaline plutonic suite typical of a destructive plate margin. New Sr and Nd isotopic whole-rock data and published whole-rock geochemistry suggest that the less-evolved intermediate (dioritic) rocks can be derived by magmatic differentiation, mainly by hornblende + plagioclase +/- Fe-Ti oxide fractional crystallization, from mafic (gabbroic) igneous precursors. Closed-system differentiation, however, cannot produce the typical intermediate (tonalitic) and silicic (granodioritic) plutonic rocks, which requires a preponderant contribution of crustal components. Intermediate and silicic plutonic rocks from Valle Fertil-La Huerta section have formed in a plate subduction setting where the thermal and material input of mantle-derived magmas promoted fusion of fertile metasedimentary rocks and favored mixing of gabbroic or dioritic magmas with crustal granitic melts. Magma mixing is observable in the field and evident in variations of chemical elemental parameters and isotopic ratios, revealing that hybridization coupled with fractionation of magmas took place in the crust. Consideration of the whole-rock geochemical and isotopic data in the context of the Famatinian-Puna magmatic belt as a whole demonstrates that the petrologic model postulated for the Sierra Valle Fertil-La Huerta section has the potential to explain the generation of plutonic and volcanic rocks across the Early Ordovician paleoarc from central and northwestern Argentina. As the petrologic model does not require the intervention of old Precambrian continental crust, the nature of the basement on which thick accretionary turbiditic sequences were deposited remains a puzzling aspect. Discussion in this paper provides insights into the nature of magmatic source rocks and mechanisms of magma generation in Cordilleran-type volcano-plutonic arcs of destructive plate margins. (C) 2010 Elsevier Ltd. All rights reserved.
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This paper discusses the ongoing ethnoarchaeological research carried out in Yamana shell middens of Tierra del Fuego. Ethnoarchaeology is used in this research as a tool to improve the archaeological methodology by testing it against anthropological, ethnographical and ethnological sources for achieving more accurate reconstructions of past societies. The ethnographical/ethnological information also is coupled with an experimental approach devised to understand physical and social processes, such as site formation processes and resource use and management. Specifically, this experimental approach was applied to the archaeological sites Tunel VII and Lanashuaia I (Tierra del Fuego, Argentina). (C) 2011 Elsevier Ltd and INQUA. All rights reserved.
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A tese aborda a constituição e as formas de ação adotadas por três centros de estudos e pesquisas em economia, financiados por grupos de empresas, cujos membros mais destacados chegaram à condução econômica, ocupando, em inúmeras ocasiões, postos governamentais, especialmente ministérios da área, presidência dos bancos centrais e outros cargos relevantes no Brasil e na Argentina, num amplo período compreendido entre os anos de 1961 e 1996, abarcando tanto a crise dos regimes populistas, quanto a passagem dos governos autoritários e democráticos, que lhes sucederam. As instituições de que trata o trabalho são, o Instituto de Pesquisas Econômicas e Sociais (IPÊS), a Fundación de Investigaciones Económicas Latinoamericanas (FIEL) e a Fundación Mediterránea (FM), escolhidas por serem atores fundamentais no desenho das políticas implementadas por distintos governos dos dois países, durante o último terço do século XX. Entidades que podem ser consideradas paradigmas de uma nova matriz de relação entre o Estado, as corporações empresariais e os técnicos vinculados fundamentalmente à área econômica, desenvolvida no período. De modo diferente das corporações de padrão mais antigo, essas instituições contaram com uma estrutura mais dinâmica e atuaram como ponte entre o Estado e os empresários para desenhar e por em prática, seja de forma direta ou indireta, políticas de transformações profundas nas suas estruturas econômicas, afastando-se dos modelos desenvolvimentistas para aproximarem-se, cada vez mais, dos moldes liberais, alcançando certo consenso no interior de diferentes frações das burguesias e de outros setores das sociedades brasileira e argentina.
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The Thermal Corridor of Uruguay River is located in the triple border of Argentine, Brazil and Uruguay, and shows an intense economic thermal tourism activity, mainly based on groundwaters from Guarani Aquifer System (GAS). Recent studies have pointed out the occurrence of high concentrations of arsenic (>10 μg/L) in GAS groundwater in this area. The complex geological and hydrogeological framework in the area is associated to the Paraná Basin geological evolution south of the Assuncion-Rio Grande Arch; it encompass paleozoic marine sequences and continental sequences permian/eotriassic to mesozoic in age, which are covered by basaltic lavas of Serra Geral Formation. Iron oxide coatings have been described in sandstones of Buena Vista and Sanga do Cabral formations, which underlie GAS units. Arsenic occurrence is associated to sodium bicarbonate groundwater with pH values over 8.0. Arsenic is released to groundwater by desorption from iron oxides/hydroxides, as result of the higher pH of these waters, indicating that arsenic is released from the units that underlie GAS units. Increase in chromium and uranium concentrations are also related to high pH groundwaters, thus indicating special care on using groundwater from this region.
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