Micromorfologia aplicada a morfometria de agregados.

A morfometria geralmente é utilizada para análise grãos em pedologia, no entanto este trabalho teve como objetivo utilizar a técnica da micromorfologia para estudo de morfometria de agregados dos solos para que possa servir como subsídio a caracterização da estrutura do solo em escala micro. Foi realizada análise de 8 lâminas correspondente a diferentes classes de solos. Foram calculadas a porosidade e atributos morfométricos, como: área, perímetro, arredondamento, maior eixo e menor eixo utilizando o software Quantiporo. Com auxílio do Microsoft® Office Excel complementou-se os atributos alongamento e compacidade dos agregados. Em geral, os resultados de porosidade concordam com classe textural e estrutura de cada perfil, encontrando-se maior porosidade em solos mais argilosos e siltosos do que nos arenosos; isso devido a quantidade de microporos nesses solos. Encontraram-se maiores semelhanças dos atributos de solos nas classes de tamanho de agregados do que em relação as diferentes classes de solos. Mesmo sendo analisada uma parte muito pequena de solo para representar uma classe de solo, os resultados mostraram coerência, visto que, houve uma similaridade entre os perfis de mesma classe e também aqueles representando uma mesma profundidade (0-10 cm)

Uniform approximation for the overlap caustic of a quantum state with its translations

The semiclassical Wigner function for a Bohr-quantized energy eigenstate is known to have a caustic along the corresponding classical closed phase space curve in the case of a single degree of freedom. Its Fourier transform, the semiclassical chord function, also has a caustic along the conjugate curve defined as the locus of diameters, i.e. the maximal chords of the original curve. If the latter is convex, so is its conjugate, resulting in a simple fold caustic. The uniform approximation through this caustic, that is here derived, describes the transition undergone by the overlap of the state with its translation, from an oscillatory regime for small chords, to evanescent overlaps, rising to a maximum near the caustic. The diameter-caustic for the Wigner function is also treated.Comment: 14 pages, 9 figure

Avaliação dos danos mecânicos na colheita de milho de alta qualidade protéica (QPM).

A maioria dos genótipos de milho contém entre 9 e 10% de proteína, pobre em lisina e triptofano, os quais são dois aminoácidos essenciais. Com a descoberta de um gene mutante chamado Opaco, que modifica a composição da proteína, obteve-se um milho com alto teor de lisina e triptofano no endosperma branco, opaco e macio, sendo estas três últimas características indesejáveis. através de ciclos avançados de seleção, obteve-se a variedade BR 2121 enriquecida dos aminoácidos essenciais, com endosperma de cor amarela, vítreo e semiduro. O objetivo do presente trabalho foi avaliar os danos mecânicos causados durante a colheita e debulha de cultivares de milho híbridos semiduros (BR 2121-QPM, "Quality Protein Maize" - milho de alta qualidade protéica e BR 3123 Normal) em duas faixas de umidade (14 16% E 16 a 18%) e quatro velocidades de rotação do cilindro debulhador (0, 500, 600 700 rpm). As espigas foram desbulhadas, utilizando-se uma colhedora-trilhadora modelo Nursey-master hidrostatic. As análises de determinação de germinação e vigor objetivaram informar sobre a qualidade das sementes, a fim de possibilitar a observação do comportamento dos grãos apos o processo de debulha (manual e mecânica). Em ambos cultivares foi observado um decréscimo da qualidade das sementes, porém mais acentuadas para a cultivar de alto valor protéico

Decoherence of Semiclassical Wigner Functions

The Lindblad equation governs general markovian evolution of the density operator in an open quantum system. An expression for the rate of change of the Wigner function as a sum of integrals is one of the forms of the Weyl representation for this equation. The semiclassical description of the Wigner function in terms of chords, each with its classically defined amplitude and phase, is thus inserted in the integrals, which leads to an explicit differential equation for the Wigner function. All the Lindblad operators are assumed to be represented by smooth phase space functions corresponding to classical variables. In the case that these are real, representing hermitian operators, the semiclassical Lindblad equation can be integrated. There results a simple extension of the unitary evolution of the semiclassical Wigner function, which does not affect the phase of each chord contribution, while dampening its amplitude. This decreases exponentially, as governed by the time integral of the square difference of the Lindblad functions along the classical trajectories of both tips of each chord. The decay of the amplitudes is shown to imply diffusion in energy for initial states that are nearly pure. Projecting the Wigner function onto an orthogonal position or momentum basis, the dampening of long chords emerges as the exponential decay of off-diagonal elements of the density matrix.Comment: 23 pg, 2 fi

Ornithogenic soil toposequence on Rata island, Fernando de Noronha archipelago, south atlantic and quaternary paleoclimatic implications.

The formation of highly phosphatized soils on sites of avian activity is a common feature of oceanic islands. We characterized a toposequence of phosphatic soils on Rata Island, to evaluate the soil genesis based on local topographic variations. For this purpose, four soils ranging from the upper hill down to the lowest landscape position on the island, representing a range of parent materials (basalt and calcareous sands), were analyzed. In the lowest landscape position a shallow Entisol was identified, strongly influenced by birds and marine sprays (Litholic Neosol), developed on " karstified" Pleistocene calcarenites; the three other soils in the upper part of the toposequence are Ornithogenic Inceptsols (Cambisols), ranging from a deep Cambisol profile on Basalt lava to intermediate Cambisols on mixed colluvial sediments of the basalt/calcareous. The lowermost Litholic Neosol is associated with a rugged landscape with strong calcarenite dissolution and karstification, related to a former wetter climate. The soil phosphatization is clearly an inherited process of the Late Quaternary age, when climate conditions were different. Initial weathering took place in the last interglacial period, under wetter conditions during which the Tertiary basalts were strongly weathered, leaving corestones in a saprolitic, oxidized mass. In the late Pleistocene, a gentle surface distributed these weathering products along the pediment slopes as colluvial materials, whereas in the coastal areas aeolian processes formed large sand dunes composed of reworked calcareous sands from marine sources during a time of very low sea level. During this time, widespread bird activity accounted for secondary apatite formation on the surface of calcareous oolites. Finally, the Holocene warming was accompanied by increasing sea level, enhanced tropical weathering, Fe and Al mobility and variscite formation superimposed on degraded Ca-phosphates, forming two phase phosphatic aggregates

Factors controlling spatio-temporal variation in carbon dioxide efflux from surface litter, roots, and soil organic matter at four rain forest sites in the eastern Amazon

[1] This study explored biotic and abiotic causes for spatio-temporal variation in soil respiration from surface litter, roots, and soil organic matter over one year at four rain forest sites with different vegetation structures and soil types in the eastern Amazon, Brazil. Estimated mean annual soil respiration varied between 13-17 t C ha(-1) yr(-1), which was partitioned into 0-2 t C ha(-1) yr(-1) from litter, 6-9 t C ha(-1) yr(-1) from roots, and 5-6 t C ha(-1) yr(-1) from soil organic matter. Litter contribution showed no clear seasonal change, though experimental precipitation exclusion over a one-hectare area was associated with a ten-fold reduction in litter respiration relative to unmodified sites. The estimated mean contribution of soil organic matter respiration fell from 49% during the wet season to 32% in the dry season, while root respiration contribution increased from 42% in the wet season to 61% during the dry season. Spatial variation in respiration from soil, litter, roots, and soil organic matter was not explained by volumetric soil moisture or temperature. Instead, spatial heterogeneity in litter and root mass accounted for 44% of observed spatial variation in soil respiration (p < 0.001). In particular, variation in litter respiration per unit mass and root mass accounted for much of the observed variation in respiration from litter and roots, respectively, and hence total soil respiration. This information about patterns of, and underlying controls on, respiration from different soil components should assist attempts to accurately model soil carbon dioxide fluxes over space and time

Rendimento industrial e composição centesimal de cultivares de arroz vermelho, integral e semipolido.

O objetivo deste trabalho foi caracterizar o rendimento industrial e a composição centesimal cultivares de arroz vermelho, integral e semi-polido. As amostras foram oriundas da EMBRAPA Meio Norte, sendo as cultivares Caqui e Vermelho, tradicionais da região, e a MNA901 oriunda do programa de Melhoramento Genético desta Unidade. O arroz foi avaliado na forma integral e semi-polido, procurando-se obter visualmente o mesmo grau de processamento de uma amostra comercial