Group Approach to Quantization of Yang-Mills Theories: A Cohomological Origin of Mass

New clues for the best understanding of the nature of the symmetry-breaking mechanism are revealed in this paper. A revision of the standard gauge transformation properties of Yang-Mills fields, according to a group approach to quantization scheme, enables the gauge group coordinates to acquire dynamical content outside the null mass shell. The corresponding extra (internal) field degrees of freedom are transferred to the vector potentials to conform massive vector bosons.Comment: 21 pages, LaTeX, no figures; final for

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

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.

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

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

A exploração de algumas características agronômicas e morfológicas na seleção de Panicum maximum para condições silvipastoris.

Sistemas silvipastoris são uma alternativa sustentável de produção animal e vegetal e sua utilização tem crescido nos últimos anos. Seu sucesso depende da identificação de gramíneas tolerantes ao sombreamento. Com o objetivo de avaliar parâmetros genéticos que possam determinar a seleção e o melhoramento de Panicum maximum, foi realizado um experimento na Embrapa Gado de Corte, em Campo Grande, MS, em vasos, com 25 genótipos promissores sob três níveis de sombreamento artificial (0, 50 e 70%). Foram realizados quatro cortes e avaliados as produções das matérias secas total e foliar e de raízes no último corte, porcentagem de folhas, altura das plantas, número de perfilhos e valores SPAD. Altas herdabilidades foram encontradas para numero de perfilhos, porcentagem de folhas e altura das plantas, indicando uma elevada acurácia na seleção para estas características. Com exceção da variável matéria seca de raízes, as outras características apresentaram uma alta correlação entre os ambientes, portanto, a seleção pode ser realizada independente dos níveis de sombreamento. O número de perfilhos apresentou a maior variação genética disponível para a realização do melhoramento, devido ao seu alto coeficiente de variação genética. A variável produção de raízes, é importante na seleção de genótipos em condições de sombreamento, por ter sido a variável que mais foi afetada pelos níveis de sombreamento.CNPGC

Germinação de esporos de Puccinia polysora por extratos aquosos de Mikania glomerata

Corn rust requires chemical fungicides as the main method for its control. This research aimed to evaluate the spore germination of the fungus Puccinia polysora, responsible for corn rust, using static aqueous extract of guaco (Mikania glomerata). The extract was obtained by hydrating whole leaves of guaco in distilled water and then it was kept in the refrigerator for 24 hours. Afterwards, the extract was filtered with filter paper and diluted in water until it reached the concentrations of 1, 2, 3, 4 and 5%. The control was prepared with distilled water. Aliquots of 40 µL of the extract and 40 µL of spore suspension of P. polysora (1 x 104 spores mL-1), obtained in a commercial farming area in Toledo (Paraná, Brazil), were spread over the surface of a microscope slide covered with a thin layer (1 mL) of water agar at 1%, placed in gerbox boxes and kept in the dark for 24 hours at 22 °C. Later, the percentage of germinated spores was determined by counting them under the microscope. The results were analyzed by ANAVA and regression test, and they indicated that all the concentrations inhibited the germination of spores, reaching 74% in the highest concentration tested, when compared to the control.A ferrugem polisora do milho possui como principal método de controle os fungicidas químicos. Esta pesquisa visou avaliar a germinação dos esporos do fungo Puccinia polysora, responsável pela ferrugem do milho, com extrato aquoso estático de guaco (Mikania glomerata). O extrato de guaco foi obtido por meio da hidratação das folhas inteiras em água destilada e mantido na geladeira por 24 horas. Em seguida, filtrou-se com papel filtro e diluiu-se em água até atingir as concentrações de 1, 2, 3, 4 e 5%. A testemunha foi representada com água destilada. Alíquotas de 40 µL do extrato e 40 µL da suspensão de esporos de P. polysora (1x104 esporos mL-1) obtidas em uma lavoura comercial da cidade de Toledo (PR), foram distribuídas sobre a superfície da lâmina de microscopia revestida por fina camada (1 mL) de ágar-água a 1% e acondicionadas em caixas de gerbox no escuro por 24 horas em temperatura de 22 ºC. Posteriormente, determinou-se a porcentagem de esporos germinados por contagem em microscópio. Os resultados foram analisados pela ANAVA e pelo teste de regressão e indicaram que todas as concentrações inibiram a germinação de esporos, atingindo 74% na maior concentração testada, quando comparada a testemunha

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

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

Preventive and Therapeutic Euphol Treatment Attenuates Experimental Colitis in Mice

BACKGROUND: The tetracyclic triterpene euphol is the main constituent found in the sap of Euphorbia tirucalli. This plant is widely known in Brazilian traditional medicine for its use in the treatment of several kinds of cancer, including leukaemia, prostate and breast cancers. Here, we investigated the effect of euphol on experimental models of colitis and the underlying mechanisms involved in its action. METHODOLOGY/PRINCIPAL FINDINGS: Colitis was induced in mice either with dextran sulfate sodium (DSS) or with 2,4,6-trinitrobenzene sulfonic acid (TNBS), and the effect of euphol (3, 10 and 30 mg/kg) on colonic injury was assessed. Pro-inflammatory mediators and cytokines were measured by immunohistochemistry, enzyme-Linked immunoabsorbent assay (ELISA), real time-polymerase chain reaction (RT-PCR) and flow cytometry. Preventive and therapeutic oral administration of euphol attenuated both DSS- and TNBS-induced acute colitis as observed by a significant reduction of the disease activity index (DAI), histological/microscopic damage score and myeloperoxidase (MPO) activity in colonic tissue. Likewise, euphol treatment also inhibited colon tissue levels and expression of IL-1β, CXCL1/KC, MCP-1, MIP-2, TNF-α and IL-6, while reducing NOS2, VEGF and Ki67 expression in colonic tissue. This action seems to be likely associated with inhibition of activation of nuclear factor-κB (NF-κB). In addition, euphol decreased LPS-induced MCP-1, TNF-α, IL-6 and IFN-γ, but increased IL-10 secretion from bone marrow-derived macrophages in vitro. Of note, euphol, at the same schedule of treatment, markedly inhibited both selectin (P- and E-selectin) and integrin (ICAM-1, VCAM-1 and LFA-1) expression in colonic tissue. CONCLUSIONS/SIGNIFICANCE: Together, these results clearly demonstrated that orally-administered euphol, both preventive or therapeutic treatment were effective in reducing the severity of colitis in two models of chemically-induced mouse colitis and suggest this plant-derived compound might be a potential molecule in the management of inflammatory bowel diseases