306 research outputs found

    Instabilities and propagation of neutrino magnetohydrodynamic waves in arbitrary direction

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    In a previous work [16], a new model was introduced, taking into account the role of the Fermi weak force due to neutrinos coupled to magnetohydrodynamic plasmas. The resulting neutrino-magnetohydrodynamics was investigated in a particular geometry associated with the magnetosonic wave, where the ambient magnetic field and the wavevector are perpendicular. The corresponding fast, short wavelength neutrino beam instability was then obtained in the context of supernova parameters. The present communication generalizes these results, allowing for arbitrary direction of wave propagation, including fast and slow magnetohydrodynamic waves and the intermediate cases of oblique angles. The numerical estimates of the neutrino-plasma instabilities are derived in extreme astrophysical environments where dense neutrino beams exist

    Numerical Thermal Analysis of a T Jump System Used for Studying Polymer Behaviour

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    Acknowledgements: The authors would like to acknowledge the financial support from Fundação da Ciência e Tecnologia (Portugal) as part of the UC4EP (Understanding Crystallisation for Enhanced Polymer Properties) at CDRSP PTDC/CTM-POL/7133/2014, UID/Multi/04044/2013, PAMI Nº 022158 and the Fundo Europeu de Desenvolvimento Regional (FEDER), Programa Portugal 2020, through the Programa Operacional Regional do Centro 2020 (CENTRO-01-0145-FEDER-022158). The neutron scattering measurement was performed at the STFC ISIS facilities (United Kingdom).The processing of polymers is highly complex. The study of their crystallisation assumes an important role and needs to be carefully detailed. Scattering experiments can be used to study polymer molecular organisation. However these procedures are still very multifaceted leading to the need for planning all the details in the experiments that are to be performed. This manuscript presents a finite element model developed to study the temperature variation of a T Jump System, which has been used for studying polymer behaviour with the NIMROD instrument at the ISIS Neutron and Muon Source, UK. Results show that the variation across the sample was 2ºC at a maximum temperature of 70ºC and 1ºC at a maximum temperature of 50ºC.info:eu-repo/semantics/publishedVersio

    Particle creation in a Robertson-Walker Universe revisited

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    We reanalyze the problem of particle creation in a 3+1 spatially closed Robertson-Walker space-time. We compute the total number of particles produced by this non-stationary gravitational background as well as the corresponding total energy and find a slight discrepancy between our results and those recently obtained in the literatur

    Temperature inversion symmetry in the Casimir effect with an antiperiodic boundary condition

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    We present explicitly another example of a temperature inversion symmetry in the Casimir effect for a nonsymmetric boundary condition. We also give an interpretation for our result.Comment: 4 page

    Comportamento de espécies de citros para o Citrus Tristeza virus (CTV) em diferentes ecossistemas.

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    A tristeza dos citros, causada pelo Citrus tristeza virus (CTV), levou a dizimação dos pomares brasileiros em décadas passadas. O convívio com esta doença, endêmica no Brasil, só foi possível por meio da utilização de porta-enxertos tolerantes e pela pré-imunização de copas muito suscetíveis. O estabelecimento da citricultura em diferentes ecossistemas na Bahia, associado ao uso de novas variedades, torna necessário estudar o seu comportamento. Isto permitirá a seleção de plantas mais tolerantes para cada local.PDF. 161_11

    Coupling between ion-acoustic waves and neutrino oscillations

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    The work investigates the coupling between ion-acoustic waves and neutrino flavor oscillations in a nonrelativistic electron-ion plasma under the influence of a mixed neutrino beam. Neutrino oscillations are mediated by the flavor polarization vector dynamics in a material medium. The linear dispersion relation around homogeneous static equilibria is developed. When resonant with the ion-acoustic mode, the neutrino flavor oscillations can transfer energy to the plasma exciting a new fast unstable mode in extreme astrophysical scenarios. The growth rate and the unstable wavelengths are determined in typical type II supernova parameters. The predictions can be useful for a new indirect probe on neutrino oscillations in nature

    Leukocyte Associated Immunoglobulin Like Receptor 1 Regulation and Function on Monocytes and Dendritic Cells During Inflammation

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    Inhibitory receptors are crucial immune regulators and are essential to prevent exacerbated responses, thus contributing to immune homeostasis. Leukocyte associated immunoglobulin like receptor 1 (LAIR-1) is an immune inhibitory receptor which has collagen and collagen domain containing proteins as ligands. LAIR-1 is broadly expressed on immune cells and has a large availability of ligands in both circulation and tissues, implicating a need for tight regulation of this interaction. In the current study, we sought to examine the regulation and function of LAIR-1 on monocyte, dendritic cell (DC) and macrophage subtypes, using different in vitro models. We found that LAIR-1 is highly expressed on intermediate monocytes as well as on plasmacytoid DCs. LAIR-1 is also expressed on skin immune cells, mainly on tissue CD14(+) cells, macrophages and CD1c(+) DCs. In vitro, monocyte and type-2 conventional DC stimulation leads to LAIR-1 upregulation, which may reflect the importance of LAIR-1 as negative regulator under inflammatory conditions. Indeed, we demonstrate that LAIR-1 ligation on monocytes inhibits toll like receptor (TLR)4 and Interferon (IFN)-alpha- induced signals. Furthermore, LAIR-1 is downregulated on GM-CSF and IFN-gamma monocyte-derived macrophages and monocyte-derived DCs. In addition, LAIR-1 triggering during monocyte derived-DC differentiation results in significant phenotypic changes, as well as a different response to TLR4 and IFN-alpha stimulation. This indicates a role for LAIR-1 in skewing DC function, which impacts the cytokine expression profile of these cells. In conclusion, we demonstrate that LAIR-1 is consistently upregulated on monocytes and DC during the inflammatory phase of the immune response and tends to restore its expression during the resolution phase. Under inflammatory conditions, LAIR-1 has an inhibitory function, pointing toward to a potential intervention opportunity targeting LAIR-1 in inflammatory conditions

    Patógenos associados a doenças de plantas ornamentais na região metropolitana de Salvador, Bahia.

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    O mercado de flores e plantas ornamentais está se expandido na Bahia, sendo grande a diversidade de espécies cultivadas. Pode-se considerar que, atualmente, a produção de flores e plantas ornamentais é uma importante alternativa de trabalho e renda para as mais diversas classes da população baiana.PDF. 157_11

    Clínica fitopatológica da EBDA ? identificação de agentes etiológicos de doenças em diversos hospedeiros.

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    As plantas cultivadas são acometidas por diversas doenças principalmente em agroecossistemas simplificados, podendo causar grandes perdas na produção e prejuízos aos agricultores. Neste sentido, é recomendada a resolução dos problemas relacionados à ocorrência de doenças de plantas, com base, frequentemente, na conservação dos recursos naturais e no aumento da diversidade biológica, de modo a atender a demanda crescente de práticas mais sustentáveis para a agricultura, sem riscos à saúde humana.PDF. 156_11

    Avaliação do uso de fertilizante foliar no comportamento de maracujazeiro amarelo infectado com o vírus do endurecimento dos frutos.

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    A virose do endurecimento é uma das doenças mais importantes do maracujazeiro, dada a dificuldade de controle. O presente trabalho tem o objetivo de avaliar o uso de fertilizante foliar na indução de resistência em mudas de maracujá amarelo para o vírus do endurecimento dos frutos causados por Potyvirus.PDF. 149_11
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