12,791 research outputs found

    Conditions for the onset of the current filamentation instability in the laboratory

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    Current Filamentation Instability (CFI) is capable of generating strong magnetic fields relevant to explain radiation processes in astrophysical objects and lead to the onset of particle acceleration in collisionless shocks. Probing such extreme scenarios in the laboratory is still an open challenge. In this work, we investigate the possibility of using neutral e−e^{-} e+e^{+} beams to explore the CFI with realistic parameters, by performing 2D particle-in-cell simulations. We show that CFI can occur unless the rate at which the beam expands due to finite beam emittance is larger than the CFI growth rate and as long as the role of competing electrostatic two-stream instability (TSI) is negligible. We also show that the longitudinal energy spread, typical of plasma based accelerated electron-positron fireball beams, plays a minor role in the growth of CFI in these scenarios

    The pinewood nematode, Bursaphelenchus xylophilus, in Madeira Island

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    The environmental conditions in Madeira Island are favorable for the presence and dissemination of the pinewood nematode (PWN), Bursaphelenchus xylophilus. Five hundred Pinus pinaster wood samples were collected in several forest areas and PWN was detected in 22.8 % of the samples. Bursaphelenchus xylophilus isolates from Madeira Island displayed the species-specific diagnostic characters. A morphological variation in the female tail terminus was detected. In most females, the tail presented a broadly rounded terminus and, occasionally, a digitate terminus with a terminal nipple-like extension resembling a mucro. PCR ITS-RFLP analysis revealed that Madeira Island isolates exhibited patterns specific to the species B. xylophilus and similar to virulent isolates. Amplified ITS regions were further sequenced and no genetic diversity was found for this genomic region among 17 Portuguese isolates (Madeira Island and Continental Portugal). Phylogenetic analysis revealed that Portuguese isolates grouped with isolates from China, Korea and one isolate from Japa

    Direitos das criança hospitalizada: evidências da investigação académica produzida em Portugal

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    Poster apresentado nas I Jornadas do Mestrado de Enfermagem de Saúde Infantil e Pediatria, organizadas pela Escola Superior de Enfermagem do Port

    Avaliação de novas variedades de mangueiras com potencial para mesa e indústria no Recôncavo Baiano.

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    O Brasil é o sétimo produtor mundial de manga, com aproximadamente 1,25 milhão de toneladas por ano em área superior a 76 mil hectares, e o segundo maior exportador com mais de 127 mil toneladas. O Nordeste participa com mais de 70% da produção nacional e a Bahia é o primeiro estado em área plantada com 26.991 ha, correspondendo a 42% da produção nacional
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