18,240 research outputs found

    Some remarks on the attractor behaviour in ELKO cosmology

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    Recent results on the dynamical stability of a system involving the interaction of the ELKO spinor field with standard matter in the universe have been reanalysed, and the conclusion is that such system does not exhibit isolated stable points that could alleviate the cosmic coincidence problem. When a constant parameter δ\delta related to the potential of the ELKO field is introduced in the system however, stable fixed points are found for some specific types of interaction between the ELKO field and matter. Although the parameter δ\delta is related to an unknown potential, in order to satisfy the stability conditions and also that the fixed points are real, the range of the constant parameter δ\delta can be constrained for the present time and the coincidence problem can be alleviated for some specific interactions. Such restriction on the ELKO potential opens possibility to apply the ELKO field as a candidate to dark energy in the universe, and so explain the present phase of acceleration of the universe through the decay of the ELKO field into matter.Comment: 17 pages, section III with minor changes and section IV rewritten with a new analysi

    Sistematização de experiências para a transição agroecológica no Distrito Federal.

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    Como objetivo de sistematizar algumas experiências de transição agroecológica no Distrito Federal esse trabalho foi realizado tendo como base o manejo de hortaliças em unidades familiares de produção. Foram selecionadas 07 propriedades em processo de transição agroecológica e realizado um diagnóstico em quatro fases: fase I - identificação de propriedades em transição agroecológica no DF; fase II- construção de um questionário semi estruturado para o diagnóstico das propriedades; fase III entrevista aos técnicos extensionistas e agricultores e ; fase IV análise dos dados.Trabalho 4. Seminário de Agroecologia do Distrito Federal e Entorno, Brasilia, DF

    Effective lagrangian for a mass dimension one fermionic field in curved spacetime

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    In this work we use momentum-space techniques to evaluate the propagator G(x,x)G(x,x^{\prime}) for a spin 1/21/2 mass dimension one spinor field on a curved Friedmann-Robertson-Walker spacetime. As a consequence, we built the one-loop correction to the effective lagrangian in the coincidence limit. Going further we compute the effective lagrangian in the finite temperature regime. We arrive at interesting cosmological consequences, as time-dependent cosmological `constant', fully explaining the functional form of previous cosmological models.Comment: 9 pages, 0 figure

    Batata 'Macaca' (Macaquinha, Rosa redonda, rosa Maçã)

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    Mapeamento por associação em plantas: conceitos básicos e perspectivas de uso no melhoramento de batata.

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    bitstream/item/35353/1/documento-248.pd

    Screening forCronobacterSpecies in Powdered and Reconstituted Infant Formulas and from Equipment Used in Formula Preparation in Maternity Hospitals

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    Background/Aims: Cronobacter spp. have been identified as being of considerable risk to neonates. The occurrence of organism in infant formulas is therefore of considerable interest. Methods: The occurrence of Cronobacter spp. in infant feeds (formulas and fortified cow’s milk) was determined using most probable number (MPN) analysis, and from formula preparation utensils. Ninety nine samples were analyzed, of which 42 were unopened cans of powdered infant formula (PIF), 25 reconstituted infant formulas in feeding bottles, 27 utensils used from the preparation of infant formula, and 5 samples of fortified cow’s milk. Presumptive Cronobacter spp. isolates were identified using the 7 allele multilocus sequence typing (MLST) scheme. Results: C. sakazakii, C. malonaticus and C. muytjensii were recovered from PIF. Although the incidence of Cronobacter in PIF was 29% (12/42), the level was low with an average of 0.54 MPN/100g. According to MLST profiling, C. sakazakii was the most frequently isolated Cronobacter species, and C. sakazakii ST4 (associated with neonatal meningitis) was recovered from 2/42 PIF samples at 0.51 and 0.92 MPN/100g. Conclusions: Cronobacter spp. can be isolated from PIF and therefore strict hygienic practices during PIF preparation are important to minimize neonate exposure and reduce the risk of severe infections
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