5,185 research outputs found

    Insights into a dinoflagellate genome through expressed sequence tag analysis

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    BACKGROUND: Dinoflagellates are important marine primary producers and grazers and cause toxic "red tides". These taxa are characterized by many unique features such as immense genomes, the absence of nucleosomes, and photosynthetic organelles (plastids) that have been gained and lost multiple times. We generated EST sequences from non-normalized and normalized cDNA libraries from a culture of the toxic species Alexandrium tamarense to elucidate dinoflagellate evolution. Previous analyses of these data have clarified plastid origin and here we study the gene content, annotate the ESTs, and analyze the genes that are putatively involved in DNA packaging. RESULTS: Approximately 20% of the 6,723 unique (11,171 total 3'-reads) ESTs data could be annotated using Blast searches against GenBank. Several putative dinoflagellate-specific mRNAs were identified, including one novel plastid protein. Dinoflagellate genes, similar to other eukaryotes, have a high GC-content that is reflected in the amino acid codon usage. Highly represented transcripts include histone-like (HLP) and luciferin binding proteins and several genes occur in families that encode nearly identical proteins. We also identified rare transcripts encoding a predicted protein highly similar to histone H2A.X. We speculate this histone may be retained for its role in DNA double-strand break repair. CONCLUSION: This is the most extensive collection to date of ESTs from a toxic dinoflagellate. These data will be instrumental to future research to understand the unique and complex cell biology of these organisms and for potentially identifying the genes involved in toxin production

    Microwave-assisted generation and reactivity of aza- and diazafulvenium methides: heterocycles via pericyclic reactions

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    Azafulvenium methides and diazafulvenium methides have been generated under microwave irradiation from 2,2-dioxo-1H,3H-pyrrolo[1,2-c]thiazoles and 2,2-dioxo-1H,3H-pyrazolo[1,5-c]thiazoles, respectively. Pericyclic reactions of these 1,7-dipole intermediates, namely, sigmatropic [1,8]H shifts, 1,7-electrocyclization or [8[pi]+2[pi]] cycloaddition led to the synthesis of a range of pyrrole and pyrazole derivatives. The first evidence for the azafulvenium methides by intermolecular trapping via [8[pi]+2[pi]] cycloaddition is reported.http://www.sciencedirect.com/science/article/B6THS-4SP3SM3-6/1/d6303d9db78919cfe9cd796c1a17d44

    Contribution of Expatriates in the Management of Subsidiaries to the Corporate Governance of International Firms: the Case of Vale

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    In the current context of globalization, where firms are increasingly operating in networks of relationships with international subsidiaries, the relevance of their corporate governance has become evident. By the same token, the contribution to corporate governance of expatriates in these subsidiaries has become an important topic of discussion. The literature is not unanimous in recognizing the contribution of expatriates. However, the question as to whether the participation of expatriates in the management of international firms’ subsidiaries is a critical success factor for their corporate governance has not been fully analyzed. This article presents the results of a study of a leading international firm - Vale - that investigated this question from a network perspective, with a view to narrowing this gap. The case study method was adopted and data collected from various sources - documental investigation, structured questionnaires and interviews. The results suggested that expatriates can contribute to the success of corporate governance, especially through informal elements pertinent to social mechanisms of governance, such as commitment, communication, flexibility, trust and interdependence. The study thus provided insights for both managers of international firms and academics on corporate governance from a network perspective

    ISOLATION AND CHARACTERIZATION OF CARBENDAZIM DEGRADING Trichoderma harzianum RIFAI MUTANTS

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    Mutants of Trichoderma harzianum Rifai, obtained after ultraviolet (UV) light exposure, showed high resistant to the fungicide benomyl. A mutant (2B6) was capable of degrading carbendazim, other fungicide of the benzimidazole fungicide. This mutant degraded 41.5% of the molecule within five days. This and others mutants (2B1 and 2B2) presented variation in size and frequency of uni-nucleated and/or bi-nucleated spores compared to the wild type. Four primers generated RAPDs patterns that allowed the mutant to be differentiated from the wild-type. It is concluded that using UV mutagenization, it is feasible to obtain strains of T. harzianum with improved pesticide degradation ability

    A First-order e-approximation algorithm for linear programs and a second-order implementation

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    This article presents an algorithm that finds an e-feasible solution relatively to some constraints of a linear program. The algorithm is a first-order feasible directions method with constant stepsize that attempts to find the minimizer of an exponential penalty function. When embedded with bisection search, the algorithm allows for the approximated solution of linear programs. We present applications of this framework to set-partitioning problems and report some computational results with first-order and second-order implementations

    Application of the volume algorithm to the approximate and exact solving of the asymmetric

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    Neste artigo apresentamos resultados computacionais obtidos com o algoritmo volumétrico, uma variante do método do subgradiente, na resolução da relaxação linear que decorre da formulação estendida de fluxo desagregado para o problema do Caixeiro Viajante Assimétrico. As experiências computacionais foram realizadas numa selecção de instâncias da TSPLib e num conjunto de instâncias geradas aleatoriamente de acordo com o Dimacs Implementation Challenge. Também experimentámos a aplicação de heurísticas durante a execução do algoritmo volumétrico. As experiências computacionais mostram sucesso moderado com instâncias de média dimensão.In this paper we present computational results with the volume algorithm, a variant of the subgradient method, when solving the linear relaxation that stems from the extended disaggregated °ow formulation of the Asymmetric Travelling Salesman Problems. Computational experiments were performed on a selection of instances from the TSPLib and some randomly generated instances according to the Dimacs Implementation Challenge. We have also tried ATSP heuristics within the volume algorithm. Computational experiments show moderated success on medium-scale instances.Fundação para a Ciência e Tecnologia - Projecto POCTI/MAT/14243/199

    Isolation of phytopathogenic fungi in seeds Caatinga tree

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    A qualidade sanitária é um parâmetro que avalia a incidência de patógenos em sementes, principalmente em espécies de produção agrícola, havendo poucos estudos sobre espécies florestais arbóreas. O presente trabalho tem como objetivo avaliar a qualidade sanitária em sementes de espécies arbóreas da Caatinga. O experimento foi conduzido no Laboratório de Fitopatologia do Centro de Ciências e Tecnologia Agroalimentar da UFCG, campus de Pombal-PB. Foram estudadas sementes de quatro espécies arbóreas: Myracrodruon urundeuva (Allemão): aroeira, Poincianella pyramidalis (Tul.): catingueira, Mimosa tenuiflora (Willd.)Poiret: jurema-preta e Libidibia ferrea (Mart) ex Tul.: pau-ferro, as mesmas foram divididas em duas subamostras, sendo uma submetida à desinfestação superficial por imersão em hipoclorito de sódio (NaClO) a 2% por 5 minutos . A sanidade das sementes foi avaliada pelo “blotter test”. Os gêneros fúngicos comumente detectados nas sementes das espécies estudadas foram: Aspergillus spp., Cladosporium spp., Fusarium spp., Penicillium spp. e Trichoderma spp.. A desinfestação com hipoclorito de sódio a 2% reduziu a incidência de fungos nas sementes das espécies estudadas. O gênero Aspergillus apresentou o maior número de colônias e diversidade de espécies fúngicas nas sementes tratadas e não tratadas, estando presente em todas as espécies arbóreas. A menor incidência de colônias fúngicas ocorreu na espécie Mimosa tenuiflora.The sanitary quality is a parameter that evaluates the incidence of pathogens in seeds, especially in species of agricultural production, so that there are few studies on forest tree species. This study aims to evaluate the sanitary quality and the effect on seeds of four species from the Caatinga region. The experiment was conducted at the Laboratory of Phytopathology from the Centre for Agri-Food Science and Technology at UFCG, Pombal - PB. Seeds from four species were studied: Myracrodruon urundeuva (Allemão): aroeira, Poincianella pyramidalis (Tul.) L.P. Queiroz: catingueira, Mimosa tenuiflora (Willd.) Poiret: jurema-preta and Libidibia ferrea (Mart ex Tul.) L.P. Queiroz: pau-ferro. The seed health was assessed using the “blotter test”. The genera of fungi commonly found in the seeds of the studied species were Aspergillus spp., Cladosporium spp., Fusarium spp., Penicillium spp. and Trichoderma spp. The disinfection with 2% sodium hypochlorite reduced the incidence of fungi on seeds of the studied species. The genus Aspergillus presented the highest number of colonies and diversity of fungal species in treated and untreated seeds, being present in all four species. The lowest incidence of fungal colonies occurred in the species Mimosa tenuiflora.Facultad de Ciencias Agrarias y Forestale

    New chemistry of diazafulvenium methides: one way to pyrazoles

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    Diazafulvenium methides generated from the solution pyrolysis of pyrazolo[1,5-c][1,3]thiazole-2,2-dioxides participate in [8[pi]+2[pi]] cycloadditions giving pyrazolo[1,5-a]pyridine derivatives. 1-Methyl-diazafulvenium, generated under flash vacuum pyrolysis reaction conditions, undergoes an intramolecular sigmatropic [1,8]H shift giving 1-vinyl-1H-pyrazoles.http://www.sciencedirect.com/science/article/B6THS-4HR7298-7/1/af0dd8d679e7977f53bc0d4af9a5b68

    Treatment of left main coronary artery lesion after late thoracic radiotherapy

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    A prevenção de complicações cardiovasculares tardias após radioterapia (RT) para tratamento de um tumor maligno é um desafio. Relatamos o caso de um jovem paciente com linfoma de Hodgkin submetido a tratamento com RT que desenvolveu doença cardíaca isquêmica no seguimento, embora não apresentasse fatores de risco cardiovasculares. Concluímos que pacientes submetidos a RT que apresentam dor torácica deveriam ser criteriosamente avaliados em relação à doença arterial coronariana.Prevention of late cardiovascular complications after radiation therapy (RT) for treatment of a malignant tumor is challenging. We report the case of a young male patient with Hodgkin's lymphoma treated with RT, who developed ischemic heart disease during follow-up, although he had no cardiovascular risk factors. We conclude that patients undergoing RT who experience chest pain should be fully investigated for coronary artery disease
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