Expanding hot flow in the black hole binary SWIFT J1753.5-0127: evidence from optical timing

We describe the evolution of optical and X-ray temporal characteristics during the outburst decline of the black hole X-ray binary SWIFT J1753.5-0127. The optical/X-ray cross-correlation function demonstrates a single positive correlation at the outburst peak, then it has multiple dips and peaks during the decline stage, which are then replaced by the precognition dip plus peak structure in the outburst tail. Power spectral densities and phase lags show a complex evolution, revealing the presence of intrinsically connected optical and X-ray quasi-periodic oscillations. For the first time, we quantitatively explain the evolution of these timing properties during the entire outburst within one model, the essence of which is the expansion of the hot accretion flow towards the tail of the outburst. The pivoting of the spectrum produced by synchrotron Comptonization in the hot flow is responsible for the appearance of the anti-correlation with the X-rays and for the optical quasi-periodic oscillations. Our model reproduces well the cross-correlation and phase lag spectrum during the decline stage, which could not be understood with any model proposed before.Comment: 13 pages, 11 figures, MNRAS submitte

Adjusting particle-size distributions to account for aggregation in tephra-deposit model forecasts

Volcanic ash transport and dispersion (VATD) models are used to forecast tephra deposition during volcanic eruptions. Model accuracy is limited by the fact that fine-ash aggregates (clumps into clusters), thus altering patterns of deposition. In most models this is accounted for by ad hoc changes to model input, representing fine ash as aggregates with density ρagg, and a log-normal size distribution with median μagg and standard deviation σagg. Optimal values may vary between eruptions. To test the variance, we used the Ash3d tephra model to simulate four deposits: 18 May 1980 Mount St. Helens; 16-17 September 1992 Crater Peak (Mount Spurr); 17 June 1996 Ruapehu; and 23 March 2009 Mount Redoubt. In 192 simulations, we systematically varied μagg and σagg, holding ρagg constant at 600 kgm-3. We evaluated the fit using three indices that compare modeled versus measured (1) mass load at sample locations; (2) mass load versus distance along the dispersal axis; and (3) isomass area. For all deposits, under these inputs, the best-fit value of μagg ranged narrowly between ∼2.3 and 2.7φ (0.20-0.15 mm), despite large variations in erupted mass (0.25-50 Tg), plume height (8.5- 25 km), mass fraction of fine ( \u3c 0.063 mm) ash (3-59 %), atmospheric temperature, and water content between these eruptions. This close agreement suggests that aggregation may be treated as a discrete process that is insensitive to eruptive style or magnitude. This result offers the potential for a simple, computationally efficient parameterization scheme for use in operational model forecasts. Further research may indicate whether this narrow range also reflects physical constraints on processes in the evolving cloud

Ice nucleation and overseeding of ice in volcanic clouds

Water is the dominant component of volcanic gas emissions, and water phase transformations, including the formation of ice, can be significant in the dynamics of volcanic clouds. The effectiveness of volcanic ash particles as ice-forming nuclei (IN) is poorly understood and the sparse data that exist for volcanic ash IN have been interpreted in the context of meteorological, rather than volcanic clouds. In this study, single-particle freezing experiments were carried out to investigate the effect of ash particle composition and surface area on water drop freezing temperature. Measured freezing temperatures show only weak correlations with ash IN composition and surface area. Our measurements, together with a review of previous volcanic ash IN measurements, suggest that fine-ash particles (equivalent diameters between approximately 1 and 1000 μm) from the majority of volcanoes will exhibit an onset of freezing between ∼250–260 K. In the context of explosive eruptions where super-micron particles are plentiful, this result implies that volcanic clouds are IN-rich relative to meteorological clouds, which typically are IN-limited, and therefore should exhibit distinct microphysics. We can expect that such “overseeded” volcanic clouds will exhibit enhanced ice crystal concentrations and smaller average ice crystal size, relative to dynamically similar meteorological clouds, and that glaciation will tend to occur over a relatively narrow altitude range

Cod response to past and current warm phases in the Seas of Iceland, a time series analysis

Climate change, and in particular global warming, is already affecting the Arctic and is expected to continue in the near future. A sustainable use the Arctic resources requires an increased understanding of its functioning that helps us anticipate change and adapt to it. Cod time series in Iceland cover a period of more than 50 years. Three distinct phases can be identified over this span of time: (1) the current warm phase characterised by relatively high cod biomasses, (2) an earlier phase (around the 1950s) with similar conditions separated by (3) some 20 years of cold temperatures and low biomasses. The aim of this study is to identify possible regime-dependent dynamics associated to these warm and cold phases that can help us identify key drivers in the current and future warm regime. To do this we compiled a database of fishing pressure, hydrographical and biological (copepods and euphausiids) variables as well as three cod population descriptors: (i) total spawning stock biomass, (ii) the population growth rate derived from matrix population models and (iii) disaggregated number at age time series. These three cod indices were subsequently regressed (GAM and threshold GAM) against the environmental and anthropogenic variables. Our results point out a probable regime-dependent mechanism where plankton effects would only be important for cod under warm conditions. No threshold-like responses were found in the population growth rate nor in the number at age for the various age classes

Infectious abortion in swine

Cover title.Includes bibliographical references

Structure of 2,5-dimethyl-1,3,4,6-tetraazacycl[3.3.3]azine, C10H9N5

Orientador: Prof. Dr. Ramón Sigifredo Cortés ParedesCoorientadora: Profª. Drª. Maria Lúcia Leite Ribeiro OkimotoTese (doutorado) - Universidade Federal do Paraná, Setor de Tecnologia, Programa de Pós-Graduação em Engenharia Mecânica. Defesa : Curitiba, 20/02/2019Inclui referências: p. 202-219Área de concentração: ManufaturaResumo: A cor é um dos elementos mais importantes da vida humana, estando conscientes disso ou não. A cor está em tudo, desde a natureza, em todos os ambientes internos e externos, nos objetos circundantes, vestuários e, até mesmo, como forma de expressão verbal, ou seja, inimaginável a vida sem cor. No entanto, milhares de pessoas no mundo não têm acesso a esta informação. O presente trabalho refere-se ao desenvolvimento de código em relevo com o objetivo de possibilitar a identificação das cores às pessoas com deficiência visual por meio do tato. Esta abordagem científica e inovadora é composta de elementos em formato tridimensional, com dimensões mínimas, inspirado no elemento principal do Sistema Braille, o ponto. A abordagem metodológica partiu de revisão bibliográfica sobre o tema, investigação e avaliação criteriosa dos códigos de cores preexistentes e o desenvolvido de um sistema inovador, fundamentado na Teoria da Cor. Os códigos foram produzidos e experimentados em duas técnicas distintas: na técnica da Manufatura Aditiva (impressão em 3D) e na impressão em papel microcapsulado que produz relevos por meio de fusora térmica. Para a realização dos experimentos participaram 18 voluntários divididos em grupos de pessoas cegas, com baixa visão e com visão normal. Sendo nove mulheres e nove homens, com idades entre 25 a 64 anos. Os resultados da pesquisa evidenciaram que este sistema de código foi facilmente assimilado e memorizado pelos participantes com o tempo médio de 18,5 minutos para o ensino-aprendizado. A análise dos valores obtidos com o tempo médio de 14,08 segundos para o reconhecimento das cores através do código, comprovou que este sistema é eficaz e eficiente no que se propôs: o reconhecimento das cores pelo sentido do tato para promover inclusão e a acessibilidade da informação às pessoas com deficiência visual. Palavras-chave: Código de cor. Tecnologia Assistiva. Acessibilidade. Comunicação. Cegueira. Deficiência visual.Abstract: Color is one of the most important elements of human life, whether you are aware of it or not. The color is at all, from nature, in all internal and external environments, in the surrounding objects, garments and, even, as a form of verbal expression, unimaginable life without color. However, thousands of people in the world do not have access to this information. The present work refers to the development of code in relief with the objective of enabling the identification of the colors to people with visual impairment through tact. This scientific and innovative approach is composed of elements in three-dimensional format, with minimal dimensions, inspired by the main element of the Braille System, the point. The methodological approach was based on a bibliographic review of the theme, investigation and judicious evaluation of the pre-existing color codes and the development of an innovative system, grounded in the Color Theory. The codes were produced and tried in two distinct techniques: in the additive manufacturing technique (3D printing) and the microcapsulated paper printing that produces reliefs by means of thermal fuser. Eighteen volunteers were divided into groups of blind people, low vision and normal vision to perform the experiments. Nine women and nine men, aged between 25 and 64 years. The results of the research evidenced that this system of code was easily assimilated and memorized by the participants with an average time of 18,5 minutes for teaching/learning. The analysis of the values obtained with the average time of 14,08 seconds for the recognition of colors through the code, proved that this system is effective and efficient with has been proposed: the recognition of colors by the sense of touch to promote inclusion and accessibility information to visually impaired persons. Keywords: Color code. Assistive Technology. Accessibility. Communication. Blindness. Visual impairment.

Development and resilience in three Arctic ecosystems: Baltic, Barents and Iceland Seas

In this GreenMAR project we look into the historical development of the marine ecosystems that surround the Nordic countries in an effort to forecast their future evolution. We pay particular attention to the way their food webs responded to similar stressors (warming) and fishing regimes in the past. We have compiled historical information on environmental and biological components, from plankton to fish, over the last 25 to 45 years, depending on the system. On these four ecosystems we have: (i) carried out multivariate analyses to describe their main trends and (ii) constructed stability landscapes to quantify their resilience. We will show these results and discuss their implications