355 resultados para Brazilian crystalline shield

em Scielo Saúde Pública - SP


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Thirteen main landform units are distinguished for the whole of the forested Amazon region, each with its specific soil pattern and vegetation structure. These landform-soil-vegetation units are delineated on a small-scale map and illustrated by a schematic cross-section. Floristic diversity of the gamma type is to be highest on the steepland-and-valley complexes of the Andean fringe, on the crystalline shield uplands, on the inselberg complexes, and on the eutric variant of the western sedimentary plains. Endemism is expected to be highest on the sandy plains, and parts of the table lands and inselberg complexes. Speciation, linked to the concept of forest refuge areas, is likely to be highest on the sandstone table lands, on the stretches of Amazon planalto, and in the areas of relict valleys, in view of the prolonged geomorphological stability of these units.

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Floristic composition and structure of vegetation were studied in two rocky outcrop areas in the semi-arid region of northeastern Brazil. From April 2007 to September 2008, 18 monthly field trips were carried out. Vascular plants were randomly collected throughout the outcrop areas. For structural analysis, 30 plots of 1 × 1 m were set in the vegetation islands. The checklist presented combines 211 species (69 families and 168 genera), although only 56 species were collected in the plots. Fabaceae (18 spp.; 8.5%), Asteraceae (17 spp.; 8%), Orchidaceae (13 spp.; 6.1%), Euphorbiaceae (13 spp.; 6.1%), Bromeliaceae (10 spp.; 4.7%), and Poaceae (eight spp.; 3.8%) are the richest families. Overall, 1,792 shrub and herbaceous specimens were counted in the plots. The Shannon-Wiener (H) diversity index values were 2.572 and 2.547 nats individual-1. The species that presented the highest absolute abundance values (number of plants) had low frequencies in the plots and vice-versa. The biological spectrum had a high proportion of phanerophytes and therophytes, followed by cryptophytes, chamaephytes, and hemicryptophytes. The studied flora shares floristic components similar to other rocky outcrop areas of the semi-arid region in northeastern Brazil, including in relation to dominant groups in the vegetation structure.

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Blood erythrocytes of Brazilian tree-frogs, Phrynohyas venulosa were found to frequently contain single, small, densely staining inclusions. Electron microscopy showed these to be icosahedral viral particles which measured from 250-280 nm in diameter; they were devoid of an envelope, and thus differed from previously described viruses of frog erythrocytes. The infected erythrocytes lacked a crystalline body.

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Changes in land use and management can affect the dynamic equilibrium of soil systems and induce chemical and mineralogical alterations. This study was based on two long-term experiments (10 and 27 years) to evaluate soil used for no-tillage maize cultivation, with and without poultry litter application (NTPL and NTM), and with grazed native pasture fertilized with cattle droppings (GrP), on the chemical and mineralogical characteristics of a Rhodic Paleudult in Southern Brazil, in comparison with the same soil under native grassland (NGr). In the four treatments, soil was sampled from the 0.0-2.5 and 2.5-5.0 cm layers. In the air-dried fine soil (ADFS) fraction (∅ < 2 mm), chemical characteristics of solid and liquid phases and the specific surface area (SSA) were evaluated. The clay fraction (∅ < 0.002 mm) in the 0.0-2.5 cm layer was analyzed by X-ray diffraction (XRD) after treatments for identification and characterization of 2:1 clay minerals. Animal waste application increased the total organic C concentration (COT) and specific surface area (SSA) in the 0.0-2.5 cm layer. In comparison to NGr, poultry litter application (NTPL) increased the concentrations of Ca and CECpH7, while cattle droppings (GrP) increased the P and K concentrations. In the soil solution, the concentration of dissolved organic C was positively related with COT levels. With regard to NGr, the soil use with crops (NTM and NTPL) had practically no effect on the chemical elements in solution. On the other hand, the concentrations of most chemical elements in solution were higher in GrP, especially of Fe, Al and Si. The Fe and Al concentrations in the soil iron oxides were lower, indicating reductive/complexive dissolution of crystalline forms. The X-ray diffraction (XRD) patterns of clay in the GrP environment showed a decrease in intensity and reflection area of the 2:1 clay minerals. This fact, along with the intensified Al and Si activity in soil solution indicate dissolution of clay minerals in soil under cattle-grazed pasture fertilized with animal droppings.

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This study analyzes the impact of globalisation on the organization and strategies outlined by the Brazilian Ministry of Foreign Affairs. The study intends to understand how countries from the periphery deal with new institutional challenges resulting from globalization, using the case of the Brazilian diplomatic service.

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The central goal of this paper is thinking about the Brazilian military power and its linking to the international ambitions of the country in the 21st century. After a comparative analysis to other BRICs and with a historical one about Brazil's strategic irrelevance, we aim to establish what the minimum military capacity Brazil would need in order to meet the country's latest international interests. Similarly, it will be discussed if the National Strategy of Defense, approved in 2008, and the recent strategic agreements signed with France represent one more step toward this minimum military capacity.

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The article analyses how Brazilian state actions and policies regarding peace operations during the Presidency of Lula da Silva relate to the country's positions and attitudes towards United Nations peacekeeping. It argues that the inconsistencies identified on the Brazilian positions reflect the lack of a clear strategic horizon guiding the country's participation in UN peacekeeping, which consequentially hinders the country emergence as a great power.

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The article deals with the internationalization of Brazilian businesses in the current decade. In the 1990s, Brazil embraced economic neoliberalism and promoted a huge opening up of its economy. At that time, Brazilian companies had to adapt rapidly. Twenty years later, the country has reinforced its presence in Latin America and has ensured a better position in the global markets, especially by through agricultural exports.

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Although Brazil has traditionally been characterized by a culture of inward-looking policy making, the presence of foreign firms in the Brazilian productive sector has always been significant. The share of foreign-owned firms is one of the highest that can be found among developing countries. This article discusses the main features of the external sector of the Brazilian economy, regarding trade flows, foreign investment, the internationalization of Brazilian entrepreneurial groups and the short-term financial requirements in foreign currencies

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The aim of this article is to analyze Brazil's foreign policy towards the South American region during President Lula's administration. As such, the article intends to highlight two specific dimensions: the extent to which foreign policy during this period has differed from previous periods and the relative importance granted by Brazilian diplomacy to recent cooperation and integration efforts, more specifically the Unasur and Mercosur. The article argues that the Lula administration has behaved differently from its predecessors by prioritizing the building up of Brazilian leadership in South America on several different fronts, especially by strengthening multilateral institutions in the region

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In the post-Cold War world, Africa has been an important focus of Brazilian foreign policy. Having a significant historical weight in building our nation, African countries are also part of the moves adopted by Brazil's foreign policy. The main purpose of the present text is to show this relevant regional dimension regarding Brazil's international insertion during the Lula era. The work is divided in two parts: the first part approaches Africa's international insertion throughout recent years and the second analyses the dimension occupied by African affairs in Brazil during the Lula era. The main argument is that the new role played by Africa in the international scene coincides with a global Brazil

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Foreign Minister of Brazil since 2003, Ambassador Celso Amorim outlines the main guidelines and accomplishments of Brazil's foreign policy under President Luiz Inácio Lula da Silva. The article provides a full-fledged, although not exhaustive, narrative of a number of diplomatic initiatives championed by Brazil over the last eight years: from the gathering of the group of developing countries in a World Trade Organization (WTO) meeting in Cancun to the negotiations that led to the Declaration of Tehran, as well as the challenges the country has been facing as its international weight grows.

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This article describes the Brazilian position on forests and climate change from 1997 to 2012. It argues that it has evolved from a veto, which excluded from the climate change regime emissions from the conversion of native forests, to a proposition, as Brazil offered its approach to the international community. It explains the change with domestic developments: governance over deforestation, the emergence of new and relevant actors, and presidential diplomacy.

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With regards to the debate about governance of climate change, it should be assumed that the Amazon region plays an important role, as this large area is highly vulnerable to its effects. In this sense, this article aims to discuss how some Amazonian municipalities of Brazil have been taking part in the complexes and multilayered processes of climate governance.