12,484 research outputs found

    Efeitos de doses de lodo de esgoto na população da broca-da-bananeira.

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    bitstream/CNPMA/6001/1/comunicado_34.pd

    Topological insulator particles as optically induced oscillators: towards dynamical force measurements and optical rheology

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    We report the first experimental study upon the optical trapping and manipulation of topological insulator (TI) particles. By virtue of the unique TI properties, which have a conducting surface and an insulating bulk, the particles present a peculiar behaviour in the presence of a single laser beam optical tweezers: they oscillate in a plane perpendicular to the direction of the laser propagation, as a result of the competition between radiation pressure and gradient forces. In other words, TI particles behave as optically induced oscillators, allowing dynamical measurements with unprecedented simplicity and purely optical control. Actually, optical rheology of soft matter interfaces and biological membranes, as well as dynamical force measurements in macromolecules and biopolymers, may be quoted as feasible possibilities for the near future.Comment: 6 pages, 5 figures. Correspondence and requests for Supplementary Material should be addressed to [email protected]

    Caracterização do sistema produtivo da mangabeira no município de Itaporanga D'Ajuda, Sergipe.

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    bitstream/CPATC-2010/21506/1/bp-48.pd

    Exactly Solvable Models of Interacting Spin-s Particles in one-dimension

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    We consider the exact solution of a many-body problem of spin-ss particles interacting through an arbitrary U(1) invariant factorizable SS-matrix. The solution is based on a unified formulation of the quantum inverse scattering method for an arbitrary (2s+1)(2s+1)-dimensional monodromy matrix. The respective eigenstates are shown to be given in terms of 2s2s creation fields by a general new recurrence relation. This allows us to derive the spectrum and the respective Bethe ansatz equations.Comment: 10 pages, plain late

    Alteração na fotossíntese causada pela mancha de alternaria (Alternaria helianthi) em girassol.

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    A mancha de Alternaria (Alternaria helianthi) diminui a área fotossintética da planta, devido à formação de manchas foliares que podem coalescer, formando áreas extensas de tecido necrosado, provocando seca prematura da folha. Objetivou-se avaliar as alterações na fotossíntese causada pela mancha de Alternaria em quatro genótipos de girassol (BRS 324, BRS 321, BRS 323 e HLA 887). O delineamento experimental foi inteiramente casualizado com 4 tratamentos e 6 repetições. Plantas de girassol cultivadas em vaso foram inoculadas com o fungo, no estágio V8 (oito folhas verdadeiras). Após 32 horas, foi feita a leitura da fotossíntese líquida nas folhas 3 e 4, utilizando o analisador de fotossíntese LI-6400XT. A taxa líquida de fotossíntese foi relacionada à severidade da doença por meio do modelo Px/Po=(1-x)b, onde Px representa a taxa fotossintética líquida de folhas com severidade de doença x (em proporção), Po representa a taxa fotossintética líquida média de folhas sadias e b representa a relação entre a lesão virtual (área foliar sem sintomas mas com fotossíntese nula) e a lesão visual (área foliar coberta por sintomas). Os valores de b determinados por regressão não-linear (R2 de 0,35 a 0,52 para os diferentes materiais) variaram entre 0,77 a 2,18. Observou-se diferença na taxa de fotossíntese líquida para os genótipos BRS 324 (1,93), BRS 321 (2,15) e BRS 323 (2,17), que apresentaram b maior que 1. Esta alteração na atividade fotossintética pode ser causada por redução na interceptação da radiação (RI), resultante da perda de área foliar fotossintetizante nas áreas próximas à região necrosada

    Young Super Star Clusters in the Starburst of M82: The Catalogue

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    Recent results from Hubble Space Telescope (HST) have resolved starbursts as collections of compact young stellar clusters. Here we present a photometric catalogue of the young stellar clusters in the nuclear starburst of M82, observed with the HST WFPC2 in Halpha (F656N) and in four optical broad-band filters. We identify 197 young super stellar clusters. The compactness and high density of the sources led us to develop specific techniques to measure their sizes. Strong extinction lanes divide the starburst into five different zones and we provide a catalogue of young super star clusters for each of these. In the catalogue we include relative coordinates, radii, fluxes, luminosities, masses, equivalent widths, extinctions, and other parameters. Extinction values have been derived from the broad-band images. The radii range between 3 and 9 pc, with a mean value of 5.7 +/- 1.4pc, and a stellar mass between 10e4 and 10e6 Mo. The inferred masses and mean separation, comparable to the size of super star clusters, together with their high volume density, provides strong evidence for the key ingredients postulated by Tenorio et al. (2003) as required for the development of a supergalactic wind.Comment: 45 pages, 5 figures, 12 tables. Accepted for publication in ApJ. Added Erratu

    On topological spin excitations on a rigid torus

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    We study Heisenberg model of classical spins lying on the toroidal support, whose internal and external radii are rr and RR, respectively. The isotropic regime is characterized by a fractional soliton solution. Whenever the torus size is very large, RR\to\infty, its charge equals unity and the soliton effectively lies on an infinite cylinder. However, for R=0 the spherical geometry is recovered and we obtain that configuration and energy of a soliton lying on a sphere. Vortex-like configurations are also supported: in a ring torus (R>rR>r) such excitations present no core where energy could blow up. At the limit RR\to\infty we are effectively describing it on an infinite cylinder, where the spins appear to be practically parallel to each other, yielding no net energy. On the other hand, in a horn torus (R=rR=r) a singular core takes place, while for R<rR<r (spindle torus) two such singularities appear. If RR is further diminished until vanish we recover vortex configuration on a sphere.Comment: 11 pages, 9 figure

    Deforestation within the higher Paraguay river basin: Brazilian Pantanal wetland: until 1976.

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    Evaluations about deforestation, until 1976, will be presented in this article, representing the decade of the 70s. Being this, the first of a series of three evaluations, that will include the decades of the 80s and the 90s. In this context, the objective of this research is to map and quantify deforested areas in the Higher Paraguay river Basin (HPB), providing the resuls per State (MT and MS), Pantanal, plateau, sub-regions and counties.SBSR 2001
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