575 resultados para Desalinhamento cambial


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Incluye Bibliografía

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Trees produce different types of woody tissue during growth. The xylem produced in the first years until a certain cambial age is called juvenile wood and has different physical, mechanical, chemical and anatomical characteristics from that produced later, when the cambial cells have matured. Thus, prior knowledge of the quality of the wood is of fundamental importance for choosing the best use of the material. This work aimed at using data from length of the tracheid and wood density to define the age transition from juvenile to mature wood. For this, three Pinus elliottii var. elliottii trees, aged 35 years, were collected at the Itapetininga Experimental Station, located in the state of São Paulo, Brazil. From each tree, disks of about 5 cm thick were obtained 0.05 m above the ground and used to determine the radial density by the gamma ray attenuation method and to measure the length of the tracheids. The results obtained by linear regression analysis showed that juvenile wood is limited to the first seven years of tree growth and the formation of mature wood occurs after twenty years. For the mature wood, there are significant differences among the averages obtained from the tracheid length and wood density.

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Hebanthe eriantha (Poir.) Pedersen, a climbing species of the Amaranthaceae increases in stem thickness by forming successive cambia. The family is dominated by herbaceous species and is constantly under discussion due to its disputed nature of the meristem. In the young stem small alternate segments of vascular cambium cease to divide and new arc of cambium initiates outside to it. The newly formed arcs connect with pre-existing alternate segments of cambium to complete the ring. On the contrary, in thick stems, instead of small segments, complete ring of cambium is replaced by new one. These new alternate segments/cambia originate from the parenchyma cells located outside to the phloem produced by previous cambium. Cambium is storied and exclusively composed of fusiform initials while ray cells remain absent at least in the early part of the secondary growth. However, large heterocellular rays are observed in 15-mm diameter stems but their frequency is much lower. In some of the rays, ray cells become meristematic and differentiate into radially arranged xylem and phloem elements. In fully grown plants, stems are composed of several successive rings of secondary xylem alternating with secondary phloem. Secondary xylem is diffuse-porous and composed of vessels, fibres, axial parenchyma while exceptionally large rays are observed only in the outermost regions of thick stems. Vessel diameter increases progressively from the centre towards the periphery of stems. Although the origin of successive cambia and composition of secondary xylem of H. eriantha remains similar to other herbaceous members of Amaranthaceae, the occurrence of relatively wider and thick-walled vessels and large rays in fully grown plants is characteristic to climbing habit. © 2013 Springer-Verlag Wien.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Incluye Bibliografía

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Pós-graduação em Economia - FCLAR

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Com a disponibilidade de novos dados de comércio foi possível repetir o exercício do estudo R.Baumann, A.M.Franco (2002), Algumas Implicações do NAFTA para a Participação do Brasil na ALCA" para o período 1998-2001, que compreende os efeitos da desvalorização cambial ocorrida a partir do início de 1999 (assim como os efeitos da retração da atividade interna na economia brasileira, que terá contribuído até certo ponto via oferta de excedente exportável). Como resultado, obtém-se um cenário razoavelmente distinto, sugerindo que para alguns setores houve efetivamente uma resposta positiva expressiva nos últimos anos. Dois aspectos diferenciam o período 1998-2001 dos períodos anteriores. A partir do início de 1999 a variação continuada - e por vezes excessiva - da taxa de câmbio, que alterou as condições de competitividade dos produtos de exportação brasileiros. Desde 2000 a essa variação veio se somar a retração do ritmo de atividade econômica, que tornou disponível um maior excedente de produção exportável a preços mais competitivos no mercado internacional. Em suma, a relação comercial com os países-membros do Nafta é tema que demanda pesquisa bem mais detalhada e cuidadosa que a simples análise do movimento dos fluxos comerciais. As explicações para o desempenho exportador brasileiro para aquela área demandam mais conhecimento factual das relações de produção e comércio, assim como das sensibilidades diferenciadas às variações de preços relativos."

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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The Inflation targeting regime is a concept of monetary policy which was adopted by several countries in the 90’s; Brazil being among these countries, having adopted it in 1999 after a currency crisis. With it theoretical structure regulated by the New – Classical theory and having as its main characteristic the prior announcement of a numerical target for the inflation, this regime was adopted by countries attempting to achieve a prices stability. The present project is going to explain the theoretical basis of the regime, as well as its implementation process in Brazil and the criticism it received. However, the main focus will be on the discussion of the employment of the IPCA (Consumer Price Index) as a measuring index for Brazil’s inflation

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Pós-graduação em Economia - FCLAR