991 resultados para 1995_01210410 TM-38 4301706
Resumo:
A implantaçao da obrigatoriedade do acesso à escola pública de Ensino Fundamental no Brasil, a partir do final dos aos 1980, produziu uma nova realidade no sistema de ensino. Por um lado, a taxa de frequência da escola básica passou de 75,03 (1990) para 92,14 (2010). Em contrapartida, a taxa de analfabetismo de pessoas com mais de 18 anos ainda é de 10,19 e somente 54,92 das pessoas com 18 anos ou mais tem Ensino Fundamental completo. Um conjunto de contradiçoes produzidas e reproduzidas sob o enfoque da justiça escolar a qual, norteia à universalizaçao do acesso a escola básica. Neste sentido, a ideia central desse trabalho foi reconhecer o perfil socioeducacional dos alunos em situaçao de fracasso escolar (repetência, distorçao idade-série e evasao escolar) no estado brasileiro que apresenta o melhor índice desenvolvimento da escola básica. Para tanto, foram analisadas as respostas de 87.607 questionários respondidos por alunos do 9o ano, participantes da Prova Brasil 2011. Com auxílio do software SPSS, foram produzidos procedimentos estatísticos para sistematizar e ampliar a análise que teve com suporte teórico as reflexoes preconizadas por distintos autores da Sociologia da Educaçao
Resumo:
Measurements of 87Sr/86Sr ratios of interstitial waters from leg 25, site 245 and leg 38, site 336 of the Deep Sea Drilling Project show that the enrichment of Sr[2+] with depth is caused both by the alteration of volcanic material and by the introduction of strontium derived from calcium carbonate. 87Sr/86 Sr ratios range from 0.70913 to 0.70794 at site 245 and from 0.70916 to 0.70694 at site 336. The low ratios compared with contemporaneous seawater reflect the release of Sr from a volcanic source having, according to material-balance calculations, a 87Sr/86 Sr ratio of about 0.7034 at site 336. At this site the source appears to be volcanic ash and not basaltic basement which acts as a sink for Sr[2+] during in situ low-temperature weathering. The volcanic contribution to the strontium enrichment in the basal interstitial waters varies from <10% at site 245 to >50% at site 336. The remaining Sr[2+] is derived from Sr-rich biogenic carbonate during diagenetic recrystallization to form Sr-poor calcite.
Resumo:
Red-brown dolomitic claystones overlay the Marsili Basin basaltic basement at ODP Site 650. Sequential leaching experiments reveal that most of the elements considered to have a hydrothermal or hydrogenous origin in a marine environment, such as Fe, Cu, Zn, Pb, Co, Ni, are present mainly in the aluminosilicate fraction of the dolomitic claystones. Their vertical distribution, content and partitioning chemistry of trace elements, and REE patterns suggest enhanced terrigenous input during dolomite formation, but no significant hydrothermal influence from the underlying basaltic basement. Positive correlations in the C and O isotopes in the dolomites reflect complex conditions during the dolomitization. The stable isotopes can be controlled in part by temperature variations during the dolomitization. Majority of the samples, however, form a trend that is steeper than expected for only temperature control on the C and O isotopes. The latter indicates possible isotopic heterogeneity in the proto-carbonate that can be related to arid climatic conditions during the formation of the basal dolomitic claystones. In addition, the dolostones stable isotopic characteristics can be influenced by diagenetic release of heavier delta18O from clay dehydration and/or alteration of siliciclastic material. Strontium and Pb isotopic data reveal that the non-carbonate fraction, the "dye" of the dolomitic claystones, is controlled by Saharan dust (75%-80%) and by material with isotopic characteristics similar to the Aeolian Arc volcanoes (20%-25%). The non-carbonate fraction of the calcareous ooze overlying the dolomitic claystones has a Sr and Pb isotopic composition identical to that of the dolomitic claystones, indicating that no change in the input sources to the sedimentary basin occurred during and after the dolomitization event. Combination of climato-tectonic factors most probably resulted in suitable conditions for dolomitization in the Marsili and the nearby Vavilov Basins. The basal dolomitic claystone sequence was formed at the initiation of the opening of the Marsili Basin (~2 Ma), which coincided with the consecutive glacial stage. The glaciation caused arid climate and enhanced evaporation that possibly contributed to the stable isotope variations in the proto-carbonate. The conductive cooling of the young lithosphere produced high heat flow in the region, causing low-temperature passive convection of pore waters in the basal calcareous sediment. We suggest that this pumping process was the major dolomitization mechanism since it is capable of driving large volumes of seawater (the source of Mg2+) through the sediment. The red-brown hue of the dolomitic claystones is terrigenous contribution of the glacially induced high eolian influx and was not hydrothermally derived from the underlying basaltic basement. The detailed geochemical investigation of the basal dolomitic sequence indicates that the dolomitization was most probably related to complex tectono-climatic conditions set by the initial opening stages of the Marsili Basin and glaciation.
Resumo:
A implantaçao da obrigatoriedade do acesso à escola pública de Ensino Fundamental no Brasil, a partir do final dos aos 1980, produziu uma nova realidade no sistema de ensino. Por um lado, a taxa de frequência da escola básica passou de 75,03 (1990) para 92,14 (2010). Em contrapartida, a taxa de analfabetismo de pessoas com mais de 18 anos ainda é de 10,19 e somente 54,92 das pessoas com 18 anos ou mais tem Ensino Fundamental completo. Um conjunto de contradiçoes produzidas e reproduzidas sob o enfoque da justiça escolar a qual, norteia à universalizaçao do acesso a escola básica. Neste sentido, a ideia central desse trabalho foi reconhecer o perfil socioeducacional dos alunos em situaçao de fracasso escolar (repetência, distorçao idade-série e evasao escolar) no estado brasileiro que apresenta o melhor índice desenvolvimento da escola básica. Para tanto, foram analisadas as respostas de 87.607 questionários respondidos por alunos do 9o ano, participantes da Prova Brasil 2011. Com auxílio do software SPSS, foram produzidos procedimentos estatísticos para sistematizar e ampliar a análise que teve com suporte teórico as reflexoes preconizadas por distintos autores da Sociologia da Educaçao
Resumo:
Subduction related mafic/ultramafic complexes marking the suture between the Wilson Terrane and the Bowers Terrane in northern Victoria Land (Antarctica) are well-suited for evaluating the magmatic and structural evolu- tion at the Palaeo-Pacific continental margin of Gondwana. One of these intru- sions is the "Tiger Gabbro Complex" (TGC), which is located at the southern end of the island-arc type Bowers Terrane. The TGC is an early Palaeozoic island-arc related layered igneous complex characterized by extraordinarly fresh sequences of ultramafic, mafic and evolved lithologies and extensive development of high-temperature high-strain zones. The goal of the present study is to establish the kinematic, petrogenetic and temporal development of the TGC in order to evaluate the magmatic and structural evolution of the deep crustal roots of this Cambrian-aged island-arc. Fieldwork during GANOVEX X was carried out to provide insight into: (i) the spatial relations between the different igneous lithologies of the TGC, (ii) the nature of the contact between the TGC and Bowers Terrane, and (iii) the high-temperature shear zones exposed in parts of the TGC. Here, we report the results of detailed field and petrological observations combined with new geochronological data. Based on these new data, we tentatively propose a petrogenetic-kinematic model for the TGC, which involves a two-phase evolution during the Ross orogeny. These phases can be summarized as: (i) an early phase (maximum age c. 530 Ma) involving tectono-magmatic processes that were active at the deep crustal level represented by the TGC within the Bowers island arc and within a general NE-SW directed contractional regime and (ii) a late phase (maximum age c. 490 Ma) attributed to the late Ross orogenic intrusion of the TGC into the higher-crustal metasedimentary country rocks of the Bowers Terrane under NE-SW directed horizontal maximum stress and subsequent cooling.