Abstract: We study the perceptual problem related to image quantization from an optimization point of view, using different metrics on the color space. A consequence of the results presented is that quantization using histogram equalization provides optimal perceptua

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Abstract: This work establishes a connection between gravitational quantum cohomology and enumerative geometry of rational curves (in a projective homogeneous variety) subject to conditions of infinitesimal nature like, for example, tangency. The key concept is that

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Abstract: Let M be an n-dimensional closed minimally immersed hypersurface in the unit sphere Sn+1. Assume in addition that M has constant scalar curvature or constant Gauss-Kronecker curvature. In this note we announce that ifM has (n−1) principal curvatures w

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Abstract: An erratum to Lemma 2.1 in Do Carmo and Zhou (2000) is presented.

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Abstract: Cell volume changes are associated with alterations of intrinsic optical signals (IOS). In submerged brain slices in vitro, afferent stimulation induces an increase in light transmission. As assessed by measurement of the largely membrane impermeant ion tet

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Abstract: The brain is an excitable media in which excitationwaves propagate at several scales of time and space. ‘‘Onedimensional’’ action potentials (millisecond scale) along the axon membrane, and spreading depressionwaves (seconds to minutes) at the three dimensi

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Abstract: The ability to introduce genetic modifications in the germ line of complex organisms has been a long-standing goal of those who study developmental biology. In this regard, the mouse, a favorite model for the study of the mammals, is unique: indeed not only

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Abstract: Developmental biology and evolutionary biology are both mature integrative disciplines which started in the 19th century and then followed parallel and independent scientific pathways. Recently, a genetical component has stepped into both disciplines (devel

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Abstract: Systematic geological studies performed in the study area allowed the characterization of six lithodemic units: three gneissic, one amphibolitic, one supracrustal and one fissure mafic. The mineral assemblage and the structural record of these lithodemic un

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Abstract: Relatively few investigations have employed electrical methods in the submarine environment, which may be promising for mineral deposits or threatened by environmental problems. We have measured the electric field using both disk and bar electrodes in the s

Resumo: Relativamente poucas investigações têm empregado métodos elétricos no ambiente submarino, o qual pode ser promissor para depósitos minerais ou ameaçado por problemas ambientais. Nós medimos o campo elétrico usando eletrodos em forma de disco e de barra na

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Abstract: U-Pb SHRIMP and Sm-Nd isotopic ages were determined for felsic metavolcanic rocks from the Silvânia Sequence and Jurubatuba Granite in the central part of the Brasília Belt. Zircon grains from a metavolcanic sample yielded 2115±23 Ma and from the granite yi

Resumo: Idades isótopicas U-Pb SHRIMP e Sm-Nd foram determinadas em rochas metavulcânicas félsicas da Seqüência de Silvânia e Granito Jurubatuba na porção central da Faixa Brasília. Grãos de zircão da rocha metavulcânica da Seqüência de Silvânia e do granito forne

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