4,685 research outputs found

    Point-Coupling Models from Mesonic Hypermassive Limit and Mean-Field Approaches

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    In this work we show how nonlinear point-coupling models, described by a Lagrangian density that presents only terms up to fourth order in the fermion condensate (ψˉψ)(\bar{\psi}\psi), are derived from a modified meson-exchange nonlinear Walecka model. The derivation can be done through two distinct methods, namely, the hypermassive meson limit within a functional integral approach, and the mean-field approximation in which equations of state at zero temperature of the nonlinear point-coupling models are directly obtained.Comment: 18 pages. Accepted for publication in Braz. J. Phy

    Endometriosis: A Rare Cause of Large Bowel Obstruction.

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    Large bowel obstruction can result in significant morbidity and mortality, especially in cases of acute complete obstruction. There are many possible causes, the most common in adults being colorectal cancer. Endometriosis is a benign disease, and the most affected extragenital location is the bowel, especially the rectosigmoid junction. However, transmural involvement and acute occlusion are very rare events. We report an exceptional case of acute large bowel obstruction as the initial presentation of endometriosis. The differential diagnosis of colorectal carcinoma may be challenging, and this case emphasizes the need to consider intestinal endometriosis in females at a fertile age presenting with gastrointestinal symptoms and an intestinal mass causing complete large bowel obstruction.info:eu-repo/semantics/publishedVersio

    Quality, innovation and performance: an exploratory study

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    The relationship between total quality management and innovation appears contradictory and complex. Literature suggests that conflicting arguments exist and while for some researchers, total quality management practices do not directly improve innovation, for others, there is a positive relationship between management practices of quality and innovation. Similarly, it remains to explain the influence of total quality management and innovation in the organizational performance. In this research, our goal is to understand the synergistic relationships between the three variables: total quality management, organizational innovation and organizational performance. This study is based on two exploratory interviews in two ISO 9000 certified SMEs (Small and Medium sized Enterprises): a Logistics Company and a Fuel Company (household fuel and equipment installation and maintenance). Based on the analysis of these interviews we present a set of propositions about the relationship between those variables. These propositions will support the formulation of hypotheses for future scientific studies in this area. Results of this research can be of high utility in understanding how the variables interact and their impact in different types of organizations

    An evaluation of the accumulation of intracellular inorganic nitrogen pools by marine microalgae in batch cultures

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    Métodos de extração, mudanças na concentração durante o crescimento e efeitos de condições de cultivo sobre conteúdos de nitrogênio inorgânico intracelular (NII - amônia, nitrito e nitrato) foram estudados em nove espécies de microalgas marinhas em cultivos estanques. As microalgas foram analisadas para comparar três métodos de extração de NII, um dos quais desenvolvido neste estudo. A extração de NII ocorre de forma eficiente com os três métodos para quatro espécies. Contudo, para cinco espécies diferenças significativas foram encontradas e os melhores resultados foram obtidos com o método novo. As microalgas acumulam formas inorgânicas de nitrogênio em proporções diferentes. As espécies apresentam concentrações de amônia ou nitrato como as mais altas e sempre menores concentrações de nitrito. Microalgas de menores volumes celulares tendem a atingir valores mais altos de NII por micrômetro cúbico (contrariamente para espécies de volumes celulares maiores), com algumas exceções (Amphidinium carterae e Nannochloropsis oculata). A adição de aeração nos cultivos determina um decréscimo na concentração de NII, favorece a assimilação de nitrogênio e gera um aumento na taxa de crescimento e na razão C:N. Concentrações altas de NII são características da fase de crescimento exponencial, mas em alguns casos sua ocorrência pode resultar de deficiência por carbono.Methods of extraction, changes in concentrations with growth, and effects of culture conditions on intracellular inorganic nitrogen pools (IIN - ammonia, nitrite, and nitrate) were studied in nine species of marine microalgae in batch cultures. The microalgae were analysed to compare three methods of extraction of IIN, one of them developed in this study. The extraction of IIN occurs efficient by with all three methods for four out of the nine species tested. However, for five species significant differences were found among the methods, the best results being obtained with the new method. Microalgae accumulate inorganic forms of nitrogen in different proportions. The species show higher concentrations of either ammonia or nitrate, and always lower concentrations of nitrite. Microalgae of smaller cellular volumes tend to attain higher values of IIN per cubic micrometer (the converse in large-volume species), with some exceptions (Amphidinium carterae and Nannochloropsis oculata). The use of aeration in the cultures determines a decrease in the concentrations of IIN, favours nitrogen assimilation, and generates an increase in growth rates and C:N ratio. High concentrations of IIN are characteristic of the exponential growth phase, but in some cases their occurrence may result from carbon deficiency

    Strategic supplier management: from contractual models to engagement partnerships

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    Nowadays, it is essential to establish a good relationship between a company and its suppliers because otherwise, this relationship cannot last long. In the understanding of recent literature and empirical studies, there is still a lack of collaboration among customers and suppliers. There is a vision for short-term profit in big companies and less attention to the quality of services provided to them. The main objective of this study is to find mechanisms that make companies in the same supply chain thrive together. To this end, 15 companies that provide services to big companies in Portugal were interviewed to assess the problems and needs that exist in relation to this type of customer. The interviewed companies provided valuable information for this study. This allowed the design of two models of good practice in order to support companies in their relations with business partners.info:eu-repo/semantics/acceptedVersio
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