1,025 research outputs found

    Scaling of variables and the relation between noncommutative parameters in Noncommutative Quantum Mechanics

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    We consider Noncommutative Quantum Mechanics with phase space noncommutativity. In particular, we show that a scaling of variables leaves the noncommutative algebra invariant, so that only the self-consistent effective parameters of the model are physically relevant. We also discuss the recently proposed relation of direct proportionality between the noncommutative parameters, showing that it has a limited applicability.Comment: Revtex4, 4 pages; version to match the published on

    First transgenic geminivirus-resistant plant in the field.

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    Bean golden mosaic virus (BGMV) belongs to the genus Begomovirus, whose genome is composed of two single-stranded DNA molecules, designated DNA-A and DNA-B, both of which are essential for infectivity. BGMV is transmitted by the whitefly Bemisia tabaci (Gennadius) in a persistent, circulative manner, causing golden mosaic in common bean. This disease is characterized by yellow-green mosaic of leaves, stunted growth and distorted pods, which may vary among genotypes

    Conversion from forests to pastures in the Colombian Amazon leads to contrasting soil carbon dynamics depending on land management practices

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    This is the author accepted manuscript. The final version is available from Wiley via the DOI in this recordStrategies to mitigate climate change by reducing deforestation and forest degradation (e.g. REDD+) require country- or region-specific information on temporal changes in forest carbon (C) pools to develop accurate emission factors. The soil C pool is one of the most important C reservoirs, but is rarely included in national forest reference emission levels due to a lack of data. Here, we present the soil organic C (SOC) dynamics along 20 years of forest-to-pasture conversion in two subregions with different management practices during pasture establishment in the Colombian Amazon: high-grazing intensity (HG) and low-grazing intensity (LG) subregions. We determined the pattern of SOC change resulting from the conversion from forest (C3 plants) to pasture (C4 plants) by analysing total SOC stocks and the natural abundance of the stable isotopes (13) C along two 20-year chronosequences identified in each subregion. We also analysed soil N stocks and the natural abundance of (15) N during pasture establishment. In general, total SOC stocks at 30 cm depth in the forest were similar for both subregions, with an average of 47.1 ± 1.8 Mg C ha(-1) in HG and 48.7 ± 3.1 Mg C ha(-1) in LG. However, 20 years after forest-to-pasture conversion SOC in HG decreased by 20%, whereas in LG SOC increased by 41%. This net SOC decrease in HG was due to a larger reduction in C3-derived input and to a comparatively smaller increase in C4-derived C input. In LG both C3- and C4-derived C input increased along the chronosequence. N stocks were generally similar in both subregions and soil N stock changes during pasture establishment were correlated with SOC changes. These results emphasize the importance of management practices involving low-grazing intensity in cattle activities to preserve SOC stocks and to reduce C emissions after land-cover change from forest to pasture in the Colombian Amazon.This study was funded by AXA Research Fund (2012‐Doc‐University‐of‐Exeter‐NAVARRETE‐D)

    Isolation and characterization of a myo-inositol-1-phosphate synthase gene from yellow passion fruit (Passiflora edulis f. flavicarpa) expressed during seed development and environmental stress.

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    Made available in DSpace on 2018-06-06T01:04:45Z (GMT). No. of bitstreams: 1 ID287091.pdf: 450380 bytes, checksum: d46d711f882606cf1b3e4e52c40c88fb (MD5) Previous issue date: 2008-01-18bitstream/item/178147/1/ID-28709-1.pd

    Avaliação do desempenho reprodutivo do rebanho leiteiro do Estado de RondÎnia: formação e gestão de banco de dados.

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    Para que o produtor se adapte aos novos moldes de produção, um intenso controle sobre os dados do rebanho deve ser empregado nos sistemas de produção de leite. AlĂ©m de produzir com eficiĂȘncia, sustentabilidade ambiental, responsabilidade social e sem desperdĂ­cios Ă© preciso desenvolver habilidades no gerenciamento e motivação de pessoas para comprar insumos, na venda da produção e na gestĂŁo adequada dos custos. Desta forma, hĂĄ necessidade que o produtor desenvolva ferramentas e prĂĄticas de monitoramento de seus dados para processar, interpretar e transformá–los em informação. VĂĄrios fatores afetam o registro e gestĂŁo dos dados da fazenda. O efetivo uso de registros representa um “divisor de ĂĄguas” na medicina moderna do gado de leite. A coleta de dados permite a definição de valores-referĂȘncia (benchmarks), padrĂ”es, nĂ­veis de interferĂȘncia e objetivos. Os registros proveem acesso aos resultados de performance do rebanho e, quando surgem os problemas, servem como a maior fonte de informação para o diagnĂłstico. Como a produção de leite tem aumentado consideravelmente na maioria das bacias leiteiras do Brasil, os profissionais “de campo” devem estar cada vez mais dedicados Ă  anĂĄlise e organização dos dados de produção.bitstream/item/57917/1/doc142-rebanholeiteiro.pd

    Probing protein sequences as sources for encrypted antimicrobial peptides

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    Starting from the premise that a wealth of potentially biologically active peptides may lurk within proteins, we describe here a methodology to identify putative antimicrobial peptides encrypted in protein sequences. Candidate peptides were identified using a new screening procedure based on physicochemical criteria to reveal matching peptides within protein databases. Fifteen such peptides, along with a range of natural antimicrobial peptides, were examined using DSC and CD to characterize their interaction with phospholipid membranes. Principal component analysis of DSC data shows that the investigated peptides group according to their effects on the main phase transition of phospholipid vesicles, and that these effects correlate both to antimicrobial activity and to the changes in peptide secondary structure. Consequently, we have been able to identify novel antimicrobial peptides from larger proteins not hitherto associated with such activity, mimicking endogenous and/or exogenous microorganism enzymatic processing of parent proteins to smaller bioactive molecules. A biotechnological application for this methodology is explored. Soybean (Glycine max) plants, transformed to include a putative antimicrobial protein fragment encoded in its own genome were tested for tolerance against Phakopsora pachyrhizi, the causative agent of the Asian soybean rust. This procedure may represent an inventive alternative to the transgenic technology, since the genetic material to be used belongs to the host organism and not to exogenous sources
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