509 research outputs found

    Evaluation of Guineagrass (\u3ci\u3ePanicum maximum\u3c/i\u3e Jacq) Hybrids in Brazil

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    Guineagrass (Panicum maximum Jacq.) is responsible for a high percentage of cattle finishing and milk production in Brazil, but presents problems of pasture degradability due to high soil fertility requirements and uneven production distribution. In order to search for new varieties to reduce these problems, over four hundred apomictic accessions of guineagrass and several sexual plants were introduced to Brazil in 1982. Agronomic evaluation took place at the National Beef Cattle Research Center of the Brazilian Agricultural Research Corporation (Embrapa Beef Cattle), in Campo Grande, MS, Brazil. Breeding of the apomictic species began in 1990 using sexual x apomictic crosses. Three sexual plants and five apomictic accessions were used in the crosses. Seventy-nine hybrids were evaluated in small plots, for forage yield, regrowth after cuts, flowering and vigor during three years. The best families were identified for each characteristic evaluated. Multivariate analysis using principal components grouped the hybrids into six clusters according to their production. Due to superior performance, hybrids in groups 6 and 2 (22 hybrids) were indicated for future regional trials in small plot evaluations and grazing studies, aiming at releasing new cultivars for pasture diversification in Brazil

    Higher-U(2,2)-spin fields and higher-dimensional W-gravities: quantum AdS space and radiation phenomena

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    A physical and geometrical interpretation of previously introduced tensor operator algebras of U(2,2) in terms of algebras of higher-conformal-spin quantum fields on the anti-de Sitter space AdS_5 is provided. These are higher-dimensional W-like algebras and constitute a potential gauge guide principle towards the formulation of induced conformal gravities (Wess-Zumino-Witten-like models) in realistic dimensions. Some remarks on quantum (Moyal) deformations are given and potentially tractable versions of noncommutative AdS spaces are also sketched. The role of conformal symmetry in the microscopic description of Unruh and Hawking's radiation effects is discussed.Comment: LaTeX, 30 pages, 2 figures, final version to appear in Class. and Quant. Gra

    Structure Constants for New Infinite-Dimensional Lie Algebras of U(N+,N-) Tensor Operators and Applications

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    The structure constants for Moyal brackets of an infinite basis of functions on the algebraic manifolds M of pseudo-unitary groups U(N_+,N_-) are provided. They generalize the Virasoro and W_\infty algebras to higher dimensions. The connection with volume-preserving diffeomorphisms on M, higher generalized-spin and tensor operator algebras of U(N_+,N_-) is discussed. These centrally-extended, infinite-dimensional Lie-algebras provide also the arena for non-linear integrable field theories in higher dimensions, residual gauge symmetries of higher-extended objects in the light-cone gauge and C^*-algebras for tractable non-commutative versions of symmetric curved spaces.Comment: 8 pages, LaTeX, no figures; minor comments added; to appear in J. Phys A (Math. Gen.

    Documentação fotográfica do desempenho silvicultural de espécies arbóreas na recuperação de áreas degradadas pela deposição de rejeitos finos da mineração de cobre.

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    O presente trabalho documenta fotograficamente o desempenho silvicultural de espécies arbóreas plantadas numa área degradada pela deposição de rejeitos finos da Mineração Caraíba situada no sertão baiano, em Jaguarari,BA. A primeira fase de seleção das espécies mais tolerantes às áreas de rejeito aconteceu no período de 1991 até 1995, sendo as espécies arbóreas/arbustivas testadas: algaroba (Prosopis juliflora), angico (Anadenanthera columbina),aroeira(Myracrod), entre outras

    Sampling Theorem and Discrete Fourier Transform on the Riemann Sphere

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    Using coherent-state techniques, we prove a sampling theorem for Majorana's (holomorphic) functions on the Riemann sphere and we provide an exact reconstruction formula as a convolution product of NN samples and a given reconstruction kernel (a sinc-type function). We also discuss the effect of over- and under-sampling. Sample points are roots of unity, a fact which allows explicit inversion formulas for resolution and overlapping kernel operators through the theory of Circulant Matrices and Rectangular Fourier Matrices. The case of band-limited functions on the Riemann sphere, with spins up to JJ, is also considered. The connection with the standard Euler angle picture, in terms of spherical harmonics, is established through a discrete Bargmann transform.Comment: 26 latex pages. Final version published in J. Fourier Anal. App

    Therapeutic intranasal vaccine HB-ATV-8 prevents atherogenesis and non-alcoholic fatty liver disease in a pig model of atherosclerosis

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    BACKGROUND AND AIMS: Atherosclerosis as an inflammatory disease involved in the etiology of cardiovascular disease worldwide, in our days demands an array of different therapeutic approaches in order to soon be able to visualize an effective prevention. Based on an immunotherapeutic approach, we designed a non-invasive vaccine (HB-ATV-8), contained in a micellar nanoparticle composed of lipids and a peptide segment derived from the C-terminus of the cholesterol-ester transfer protein (CETP). Now we extend our successful proof of concept from the rabbit to a porcine model and investigated its effect in an attempt to undoubtedly establish the efficacy of vaccination in a model closer to the human. METHODS: A preclinical trial was designed to study the efficacy of vaccine HB-ATV-8 in pigs (Large White × Landrace). Male experimental animals were fed with standard diet (control), high fat diet (HFD) or the same HFD but treated with HB-ATV-8 (HFD + Vaccine) applied nasally for up to 7 months. All biochemical and enzymatic analyses were performed in peripheral venous blood and thoracic aorta and liver samples examined using conventional, two-photon excitation and second harmonic generation microscopy to identify atherosclerotic and hepatic lesions. mRNA concentrations for KLF2, ACTA2, SOD1, COL1A1 genes and protein levels for PPARα and ABCA1 were quantified in aorta and liver respectively using qPCR and Western blot analysis. RESULTS: The administration of vaccine HB-ATV-8 induced anti-CETP IgG antibodies and reduced atherosclerotic and hepatic lesions promoted by the high fat diet. In addition, plasma triglyceride levels of vaccine treated pigs fed the HFD were similar to those of control group, in contrast to high concentrations reached with animals exclusively fed with HFD. Moreover, HFD promotes a tendency to decreased hepatic PPARα levels and increase in aorta gene expression of KLF2, ACTA2, SOD1 and COL1A1, while vaccine application promotes recovery close to control values. CONCLUSIONS: Vaccine HB-ATV-8 administration constitutes a promissory preventive approach useful in the control of atherogenesis and fatty liver disease. The positive results obtained, the non-invasive characteristics of the vaccine, the simple design employed in its conception and its low production cost, support the novelty of this therapeutic strategy designed to prevent the process of atherogenesis and control the development of fatty liver disease

    Geoelectric method applied in correlation between physical characteristics and electrical properties of the soil.

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    This paper presents the study of the relationship between electrical properties and physical characteristics of the soil. Measures of apparent electrical resistivity of the soil were made for different types of soil, varying moisture content gradually while maintaining a constant compaction, and then varying the compaction and relating it to a constant humidity. Development of a correlation surface is proposed in order to identify granulometry of the soil from moisture and compaction measurements. For the study of spatial variability, two areas were chosen to allow the change of moisture content and compaction in order to verify the measurement capacity of apparent electrical resistivity of the soil as methodology to identify change in soil dynamics. Results obtained show correlations among apparent electrical resistivity of the soil, moisture, soil compaction and clay content

    Symmetries of Non-Linear Systems: Group Approach to their Quantization

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    We report briefly on an approach to quantum theory entirely based on symmetry grounds which improves Geometric Quantization in some respects and provides an alternative to the canonical framework. The present scheme, being typically non-perturbative, is primarily intended for non-linear systems, although needless to say that finding the basic symmetry associated with a given (quantum) physical problem is in general a difficult task, which many times nearly emulates the complexity of finding the actual (classical) solutions. Apart from some interesting examples related to the electromagnetic and gravitational particle interactions, where an algebraic version of the equivalence principle naturally arises, we attempt to the quantum description of non-linear sigma models. In particular, we present the actual quantization of the partial-trace non-linear SU(2) sigma model as a representative case of non-linear quantum field theory.Comment: 24 pages, LaTeX, no figure
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