Field sources in a Lorentz symmetry breaking scenario with a single background vector

This paper is devoted to investigating the interactions between stationary sources of the electromagnetic field, in a model which exhibits explicit Lorentz-symmetry breaking due to the presence of a single background vector. We focus on physical phenomena that emerge from this kind of breaking and which have no counterpart in Maxwell Electrodynamics

Generation of higher derivatives operators and electromagnetic wave propagation in a Lorentz-violation scenario

We study the perturbative generation of higher-derivative operators as corrections to the photon effective action, which are originated from a Lorentz violation background. Such corrections are obtained, at one-loop order, through the proper-time method, using the zeta function regularization. We focus over the lowest order corrections and investigate their influence in the propagation of electromagnetic waves through the vacuum, in the presence of a strong, constant magnetic field. This is a setting of experimental relevance, since it bases active efforts to measure non linear electromagnetic effects. After surprising cancellations of Lorentz violating corrections to the Maxwell's equation, we show that no effects of the kind of Lorentz violation we consider can be detected in such a context.Comment: v2: 13 pages, no figures, section IV considerably rewritten, main results unchanged and are now obtained in a simpler way. To appear in PL

Desempenho da bananeira em diferentes manejos do solo no sistema orgânico.

A banana (Musa spp.), uma das frutas mais consumidas mundialmente, é cultivada na maioria dos países tropicais. A produção mundial de banana em 2009 foi de aproximadamente 97,3 milhões de toneladas, ocupando o Brasil a quinta posição (7,0%).Em paralelo aconteceram também os seguintes eventos: V Seminário de Pesquisa do Recôncavo da Bahia; V Seminário Estudantil de Pesquisa da UFRB; V Seminário da Pós-Graduação da UFRB; II Seminário Regional de Pesquisa da EBDA; 5ª Jornada Científica da Embrapa Mandioca e Fruticultura; VIII Seminário Estudantil de Pesquisa e Extensão da FAMAM; Semana de Ciência, Tecnologia e Inovação no Agronegócio; Fórum de Gestores de Iniciação Científica e Tecnológica da Bahia; II Simpósio Baiano de Defesa Agropecuária; I Semana de Educação Tutorial da UFRB

Modificações na composição química e padrão de fermentação em silagens de seis híbridos de milho.

Empresas de melhoramento genético vegetal lançam vários híbridos de milho no mercado todos os anos. Grande parte desses híbridos é utilizada para a produção de silagem. Dessa forma, esse trabalho objetivou estudar as principais modificações da composição química e o padrão de fermentação das silagens produzidas por seis híbridos de milho (HD 9481, P 3041, C 435, HT 951005, HT 47C e AG 5011). As plantas inteiras do milho foram ensiladas no estádio de maturidade fisiológica (3/4 de "linha do leite"), em silos laboratoriais de PVC, com 10 cm de diâmetro. A forragem foi avaliada com 0 (zero), 1, 3, 5, 7, 14, 28 e 56 dias após a ensilagem. Foram analisados os teores de matéria seca (MS), de carboidratos solúveis (CS), de fibra detergente neutro (FDN), de proteína bruta (PB), de nitrogênio amoniacal e o pH. Os teores médios de MS nas silagens variaram de 34,51 a 42,90%. A maior parte dos CS foi consumida até o 5º dia da fermentação. Os teores de PB e de FDN permaneceram praticamente estáveis durante a ensilagem. Os valores de pH se estabilizaram a partir do 5º dia da fermentação, para a maioria dos híbridos, e foram sempre menores que 3,82 no 56º dia. Os teores de nitrogênio amoniacal, embora não tenham se estabilizado até o 56º dia da ensilagem, foram sempre menores que 10%. As silagens foram classificadas como de boa qualidade

Consumo e digestibilidade aparente da matéria seca, da proteína bruta e da energia de silagens de quatro genotipos de sorgo (Sorghum bicolor (L.) Moench) por ovinos.

The nitrogen balance, the consumption and the apparent digestibility of dry matter, crude protein and the energy of the silages of four genotypes of sorghum were evaluated. The consumption of dry matter and crude energy did not differ among the hibrids. The largest apparent digestibility of dry matter, crude energy and the consumption of digestible dry matter and energy, were observed for BR601 genotype. The largest consumption of crude protein, was observed for BR700 and the smallest for AG2002 genotypes (P<0.05). The largest apparent digestibility of protein was observed for BR601 and the smallest one for BR701 (P<0.05) genotype. The consumption of digestible protein was larger for BR601 and BR700. All treatments showed positive nitrogen balance and did not differ among them

Whole Genome Analysis of Gene Expression Reveals Coordinated Activation of Signaling and Metabolic Pathways during Pollen-Pistil Interactions in Arabidopsis

Plant reproduction depends on the concerted activation of many genes to ensure correct communication between pollen and pistil. Here, we queried the whole transcriptome of Arabidopsis (Arabidopsis thaliana) in order to identify genes with specific reproductive functions. We used the Affymetrix ATH1 whole genome array to profile wild-type unpollinated pistils and unfertilized ovules. By comparing the expression profile of pistils at 0.5, 3.5, and 8.0 h after pollination and applying a number of statistical and bioinformatics criteria, we found 1,373 genes differentially regulated during pollen-pistil interactions. Robust clustering analysis grouped these genes in 16 time-course clusters representing distinct patterns of regulation. Coregulation within each cluster suggests the presence of distinct genetic pathways, which might be under the control of specific transcriptional regulators. A total of 78% of the regulated genes were expressed initially in unpollinated pistil and/or ovules, 15% were initially detected in the pollen data sets as enriched or preferentially expressed, and 7% were induced upon pollination. Among those, we found a particular enrichment for unknown transcripts predicted to encode secreted proteins or representing signaling and cell wall-related proteins, which may function by remodeling the extracellular matrix or as extracellular signaling molecules. A strict regulatory control in various metabolic pathways suggests that fine-tuning of the biochemical and physiological cellular environment is crucial for reproductive success. Our study provides a unique and detailed temporal and spatial gene expression profile of in vivo pollen-pistil interactions, providing a framework to better understand the basis of the molecular mechanisms operating during the reproductive process in higher plants.Fundação para a Ciência e a Tecnologia grants: (FCT–PTDC/QUI/64339/06, SFRH/BD/1128/2000)