230 research outputs found

    Formation of callus on rootstock cuttings with different substrates during the forcing.

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    Nowadays the global viticulture scenario has being verifying high levels of an event known as ?young grapevine decline? related to various diseases, such as Esca, Petri and Black Foot. On the grapevine plant propagation, the process of callus formation is crucial to ensure protection against the infection of these fungus during the rooting process on the field. In the heated rooms, the formation of callus on the rootstock cuttings act like a preventive barrier against a possible infection by these fungus. The callusing process (called ?forcing?) is based on the usage of substrates for the maintenance of humidity of the cuttings and for providing optimum conditions of temperature and relative humidity in the dark chamber

    Padronização da produção de inóculo de fungos micorrízicos arbusculares.

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    Fungos micorrízicos arbusculares (FMA) são organismos benéficos às plantas, formando associação simbiótica com estas. Em virtude de que os FMAs necessitam da presença de raízes vivas para se multiplicarem, torna-se fundamental o aperfeiçoamento das metodologias de produção de inóculo de forma tradicional ou in vitro. Para produção de inóculo, normalmente são empregadas plantas de crescimento rápido, mas a quantidade de inóculo a ser utilizada por planta pode ser definida em relação ao peso do inóculo, utilizando-se normalmente 20 a 30g por vaso, ou pela quantidade de esporos presentes, sendo ideal ter no mínimo 100 esporos/100g de inóculo. Neste trabalho, foi avaliado a variação da colonização de cinco espécies de FMA (Acalospora colombiana - AC, Claroideoglomus etunicatun - CE, Dentiscutta heterogama - DH, Acalospora scrobiculata - AS e Rhizophagus clarus - RC) inoculadas em Avena strigosa Schre, cultivada em casa de vegetação.(Embrapa Uva e Vinho. Documentos, 99

    The origin of variability of the intermediate-mass black-hole ULX system HLX-1 in ESO 243-49

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    The ultra-luminous intermediate-mass black-hole system HLX-1 in the ESO 243-49 galaxy exhibits variability with a possible recurrence time of a few hundred days. Finding the origin of this variability would constrain the still largely unknown properties of this extraordinary object. Since it exhibits an intensity-hardness behavior characteristic of black-hole X-ray transients, we have analyzed the variability of HLX-1 in the framework of the disk instability model that explains outbursts of such systems. We find that the long-term variability of HLX-1 is unlikely to be explained by a model in which outbursts are triggered by thermal-viscous instabilities in an accretion disc. Possible alternatives include the instability in a radiation-pressure dominated disk but we argue that a more likely explanation is a modulated mass-transfer due to tidal stripping of a star on an eccentric orbit around the intermediate-mass black hole. We consider an evolutionary scenario leading to the creation of such a system and estimate the probability of its observation. We conclude, using a simplified dynamical model of the post-collapse cluster, that no more than 1/100 to 1/10 of Mbh < 10^4 Msun IMBHs - formed by run-away stellar mergers in the dense collapsed cores of young clusters - could have a few times 1 Msun Main-Sequence star evolve to an AGB on an orbit eccentric enough for mass transfer at periapse, while avoiding collisional destruction or being scattered into the IMBH by 2-body encounters. The finite but low probability of this configuration is consistent with the uniqueness of HLX-1. We note, however, that the actual response of a standard accretion disk to bursts of mass transfer may be too slow to explain the observations unless the orbit is close to parabolic (and hence even rarer) and/or additional heating, presumably linked to the highly time-dependent gravitational potential, are invoked.Comment: 8 pages, 2 figures. Additional figure, extended discussion. To be published in ApJ, June 10, 2011, v734 -

    Extinction and dawn of the modern world in the Carnian (Late Triassic)

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    The Carnian Pluvial Episode (Late Triassic) was a time of global environmental changes and possibly substantial coeval volcanism. The extent of the biological turnover in marine and terrestrial ecosystems is not well understood. Here, we present a meta-analysis of fossil data that suggests a substantial reduction in generic and species richness and the disappearance of 33% of marine genera. This crisis triggered major radiations. In the sea, the rise of the first scleractinian reefs and rock-forming calcareous nannofossils points to substantial changes in ocean chemistry. On land, there were major diversifications and originations of conifers, insects, dinosaurs, crocodiles, lizards, turtles, and mammals. Although there is uncertainty on the precise age of some of the recorded biological changes, these observations indicate that the Carnian Pluvial Episode was linked to a major extinction event and might have been the trigger of the spectacular radiation of many key groups that dominate modern ecosystems

    Manual de boas práticas de fabricação na vinícola.

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    As Boas Práticas de Fabricação (BPF) tem por objetivo principal a produção de produtos seguros ao consumidor, com consequente preservação da sua vida útil e melhoria em suas qualidades organolépticas. A fim de possibilitar a sistematização desses procedimentos e ajudar o setor vitivinícola, desenvolveu-se um Manual BPF tendo como base as vinícolas que participam do programa de Produção Integrada e a Cantina da Embrapa Uva e Vinho e como referência as Instruções Normativas Nº 05/2000 e Nº 17/2015, do MAPA e a RDC N° 275/2002, da ANVISA. O referido Manual pode ser dividido em três partes: introdutória, onde são descritos objetivos, âmbito de aplicação, legislações de referência, definição de termos técnicos utilizados e campos de identificação do estabelecimento; na segunda parte constam descrições da empresa, condições ambientais, instalações, edificações e saneamento, abastecimento de água, manejo de resíduos, higienização das instalações e equipamentos, móveis e utensílios utilizados, condições dos manipuladores e visitantes, como é realizado o controle integrado de vetores e pragas urbanas, a seleção das matérias-primas, ingredientes e embalagens, e o recolhimento de Alimentos; na última parte constam os fluxogramas dos produtos elaborados, os Procedimentos Operacionais Padrões (POPs), as Instruções de Trabalho e as referências utilizadas.(Embrapa Uva e Vinho. Documentos, 99

    Manual de boas práticas de fabricação/elaboração em vinícola compatível com a produção integrada de uva para processamento.

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    Manual BPF/E vem sendo exigido das vinícolas auditadas pelos fiscais agropecuários a partir da IN n°17/2015 do MAPA (BRASIL, 2015), sobre Registro de Estabelecimento e de Produto sendo, portanto, obrigatóriobitstream/item/177909/1/Livro-Documentos-105-2-ed-2018-maio.pd

    Research Update on Extreme-Mass-Ratio Inspirals

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    The inspirals of stellar-mass mass compact objects into massive black holes in the centres of galaxies are one of the most important sources of gravitational radiation for space-based detectors like LISA or eLISA. These extreme-mass-ratio inspirals (EMRIs) will enable an ambitious research program with implications for astrophysics, cosmology, and fundamental physics. This article is a summary of the talks delivered at the plenary session on EMRIs at the 10th International LISA Symposium. It contains research updates on the following topics: astrophysics of EMRIs; EMRI science potential; and EMRI modeling.Comment: 17 pages, no figures. Proceedings of the LISA Symposium X, to be published at the Journal of Physic

    Massive binary black holes in galactic nuclei and their path to coalescence

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    Massive binary black holes form at the centre of galaxies that experience a merger episode. They are expected to coalesce into a larger black hole, following the emission of gravitational waves. Coalescing massive binary black holes are among the loudest sources of gravitational waves in the Universe, and the detection of these events is at the frontier of contemporary astrophysics. Understanding the black hole binary formation path and dynamics in galaxy mergers is therefore mandatory. A key question poses: during a merger, will the black holes descend over time on closer orbits, form a Keplerian binary and coalesce shortly after? Here we review progress on the fate of black holes in both major and minor mergers of galaxies, either gas-free or gas-rich, in smooth and clumpy circum-nuclear discs after a galactic merger, and in circum-binary discs present on the smallest scales inside the relic nucleus.Comment: Accepted for publication in Space Science Reviews. To appear in hard cover in the Space Sciences Series of ISSI "The Physics of Accretion onto Black Holes" (Springer Publisher

    The S-Star Cluster at the Center of the Milky Way: On the nature of diffuse NIR emission in the inner tenth of a parsec

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    Sagittarius A*, the super-massive black hole at the center of the Milky Way, is surrounded by a small cluster of high velocity stars, known as the S-stars. We aim to constrain the amount and nature of stellar and dark mass associated with the cluster in the immediate vicinity of Sagittarius A*. We use near-infrared imaging to determine the KsK_\mathrm{s}-band luminosity function of the S-star cluster members, and the distribution of the diffuse background emission and the stellar number density counts around the central black hole. This allows us to determine the stellar light and mass contribution expected from the faint members of the cluster. We then use post-Newtonian N-body techniques to investigate the effect of stellar perturbations on the motion of S2, as a means of detecting the number and masses of the perturbers. We find that the stellar mass derived from the KsK_\mathrm{s}-band luminosity extrapolation is much smaller than the amount of mass that might be present considering the uncertainties in the orbital motion of the star S2. Also the amount of light from the fainter S-cluster members is below the amount of residual light at the position of the S-star cluster after removing the bright cluster members. If the distribution of stars and stellar remnants is strongly enough peaked near Sagittarius A*, observed changes in the orbital elements of S2 can be used to constrain both their masses and numbers. Based on simulations of the cluster of high velocity stars we find that at a wavelength of 2.2 μ\mum close to the confusion level for 8 m class telescopes blend stars will occur (preferentially near the position of Sagittarius A*) that last for typically 3 years before they dissolve due to proper motions.Comment: 14 pages, 11 figures, minor changes to match the published version in Astronomy & Astrophysic

    Formation and Evolution of Supermassive Black Holes

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    The correlation between the mass of supermassive black holes in galaxy nuclei and the mass of the galaxy spheroids or bulges (or more precisely their central velocity dispersion), suggests a common formation scenario for galaxies and their central black holes. The growth of bulges and black holes can commonly proceed through external gas accretion or hierarchical mergers, and are both related to starbursts. Internal dynamical processes control and regulate the rate of mass accretion. Self-regulation and feedback are the key of the correlation. It is possible that the growth of one component, either BH or bulge, takes over, breaking the correlation, as in Narrow Line Seyfert 1 objects. The formation of supermassive black holes can begin early in the universe, from the collapse of Population III, and then through gas accretion. The active black holes can then play a significant role in the re-ionization of the universe. The nuclear activity is now frequently invoked as a feedback to star formation in galaxies, and even more spectacularly in cooling flows. The growth of SMBH is certainly there self-regulated. SMBHs perturb their local environment, and the mergers of binary SMBHs help to heat and destroy central stellar cusps. The interpretation of the X-ray background yields important constraints on the history of AGN activity and obscuration, and the census of AGN at low and at high redshifts reveals the downsizing effect, already observed for star formation. History appears quite different for bright QSO and low-luminosity AGN: the first grow rapidly at high z, and their number density decreases then sharply, while the density of low-luminosity objects peaks more recently, and then decreases smoothly.Comment: 31 pages, 13 figures, review paper for Astrophysics Update
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