Filamentary fragmentation in a turbulent medium

We present the results of smoothed particle hydrodynamic simulations investigating the evolution and fragmentation of filaments that are accreting from a turbulent medium. We show that the presence of turbulence, and the resulting inhomogeneities in the accretion flow, play a significant role in the fragmentation process. Filaments which experience a weakly turbulent accretion flow fragment in a two-tier hierarchical fashion, similar to the fragmentation pattern seen in the Orion Integral Shaped Filament. Increasing the energy in the turbulent velocity field results in more sub-structure within the filaments, and one sees a shift from gravity-dominated fragmentation to turbulence-dominated fragmentation. The sub-structure formed in the filaments is elongated and roughly parallel to the longitudinal axis of the filament, similar to the fibres seen in observations of Taurus, and suggests that the fray and fragment scenario is a possible mechanism for the production of fibres. We show that the formation of these fibre-like structures is linked to the vorticity of the velocity field inside the filament and the filament's accretion from an inhomogeneous medium. Moreover, we find that accretion is able to drive and sustain roughly sonic levels of turbulence inside the filaments, but is not able to prevent radial collapse once the filaments become supercritical. However, the supercritical filaments which contain fibre-like structures do not collapse radially, suggesting that fibrous filaments may not necessarily become radially unstable once they reach the critical line-density.Comment: (Accepted for publication in MNRAS

The development of a universal diagnostic probe system for Tokamak fusion test reactor

The Tokamak Fusion Test Reactor (TFTR), the largest such facility in the U.S., is discussed with respect to instrumentation in general and mechanisms in particular. The design philosophy and detailed implementation of a universal probe mechanism for TFTR is discussed

CONTROLE E DISPUTA PELA DEMOCRACIA NA COMUNICAÇÃO SOCIAL

This article analyzes the current state of the Brazilian media in relation to the influence of the companies that constitute Mass Communication Enterprises in Brazil . On the other hand, observes the participation of the movements for democratizing the media. The paper looks to contribute for the theoretical debate and of perspectives for a better performance on the part of the activists of communitarian communication, as well as the popular movement. The article goes through a bibliographical and documental research, besides the analysis of recent data, looking to evidence the importance of the constitution of democratic public politics for the people empowerment in our country

Variedades de abacaxi.

Todas as variedades de abacaxi cujo interesse é o fruto, seja para consumo in natura ou para processamento, pertencem à espécie Ananas comosus var. comosus. Alguns clones de Ananas comosus var. erectifolius, Ananas comosus var. ananassoides e Ananas comosus var. bracteatus são cultivados para produção de fibra ou para fins ornamentais. Recentemente, houve grande incremento nestas formas de utilização. A variedade de abacaxi predominantemente cultivada no mundo é a Smooth Cayenne, responsável por cerca de 70% da produção mundial de abacaxi. Contudo, outras variedades como Singapore Spanish, Queen, Red Spanish, Pérola e Perolera são muito cultivadas e difundidas em nível mundial (Leal, 1990). No Brasil, onde a área de plantio em 2002 foi de 62.597 ha, com produção de 1.430.018 mil frutos e rendimento de 22.845 frutos/ha (IBGE, 2003), a variedade mais plantada é a Pérola, responsável por cerca de 80% da produção brasileira de abacaxi havaiano, cujos plantios se concentram no Sudeste do país, principalmente em São Paulo e na região do Triângulo Mineiro.bitstream/item/81569/1/Circular-Tecnica-63-Variedade-Abacaxi-Renato-Cabral-2003.pdfMemória

Daytime turbulent exchange between the Amazon forest and the atmosphere

Detailed observations of turbulence just above and below the crown of the Amazon rain forest during the wet season are presented. The forest canopy is shown to remove high frequency turbulent fluctuations while passing lower frequencies. Filter characteristics of turbulent transfer into the Amazon rain forest canopy are quantified. Simple empirical relations that relate observed turbulent heat fluxes to horizontal wind variance are presented. Changes in the amount of turbulent coupling between the forest and the boundary layer associated with deep convective clouds are presented both as statistical averages and as a series of case studies. These convective processes during the rainy season are shown to alter the diurnal course of turbulent fluxes. In wake of giant coastal systems, no significant heat or moisture fluxes occur for up to a day after the event. Radar data is used to demonstrate that even small raining clouds are capable of evacuating the canopy of substances normally trapped by persistent static stability near the forest floor. Recovery from these events can take more than an hour, even during mid-day. In spite of the ubiquitous presence of clouds and frequent rain during this season, the average horizontal wind speed spectrum is well described by dry CBL similarity hypotheses originally found to apply in flat terrain

Bipolar HII regions - Morphology and star formation in their vicinity - I - G319.88++00.79 and G010.32−-00.15

Our goal is to identify bipolar HII regions and to understand their morphology, their evolution, and the role they play in the formation of new generations of stars. We use the Spitzer and Herschel Hi-GAL surveys to identify bipolar HII regions. We search for their exciting star(s) and estimate their distances using near-IR data. Dense clumps are detected using Herschel-SPIRE data. MALT90 observations allow us to ascertain their association with the central HII region. We identify Class 0/I YSOs using their Spitzer and Herschel-PACS emissions. These methods will be applied to the entire sample of candidate bipolar HII regions. This paper focuses on two bipolar HII regions, one interesting in terms of its morphology, G319.88$+$00.79, and one in terms of its star formation, G010.32$-$00.15. Their exciting clusters are identified and their photometric distances estimated to be 2.6 kpc and 1.75 kpc, respectively. We suggest that these regions formed in dense and flat structures that contain filaments. They have a central ionized region and ionized lobes perpendicular to the parental cloud. The remains of the parental cloud appear as dense (more than 10^4 per cm^3) and cold (14-17 K) condensations. The dust in the PDR is warm (19-25 K). Dense massive clumps are present around the central ionized region. G010.32-00.14 is especially remarkable because five clumps of several hundred solar masses surround the central HII region; their peak column density is a few 10^23 per cm^2, and the mean density in their central regions reaches several 10^5 per cm^3. Four of them contain at least one massive YSO; these clumps also contain extended green objects and Class II methanol masers. This morphology suggests that the formation of a second generation of massive stars has been triggered by the central bipolar HII region. It occurs in the compressed material of the parental cloud.Comment: 32 pages, 28 figures, to be published in A&

Botulismo Infantil em Portugal – Um Lactente com Hipotonia

O Botulismo Infantil (BI) constitui uma síndrome neuroparalítica rara, potencialmente fatal, causada pela neurotoxina do Clostridium botulinum. Descreve-se o primeiro caso reportado desde o início da notificação obrigatória em Portugal (1999). Lactente de dois meses, internado por prostração, dificuldade alimentar e obstipação. Constatou-se envolvimento inicial dos pares cranianos associado a fraqueza muscular progressiva, descendente e simétrica. Constituíam factores de risco o consumo de mel caseiro e o banho com ervas de camomila. A confirmação diagnóstica foi efectuada pela pesquisa de esporos de Clostridium botulinum nas fezes e pela prova de inoculação em ratinhos. O tratamento implicou suporte respiratório e nutricional, e imunoglobulina humana anti-toxina, com evolução favorável. A clínica e o contexto epidemiológico são importantes para o diagnóstico, permitindo a instituição precoce do tratamento