4,121 research outputs found

    The rotational shear layer inside the early red-giant star KIC 4448777

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    We present the asteroseismic study of the early red-giant star KIC 4448777, complementing and integrating a previous work (Di Mauro et al. 2016), aimed at characterizing the dynamics of its interior by analyzing the overall set of data collected by the {\it Kepler} satellite during the four years of its first nominal mission. We adopted the Bayesian inference code DIAMOND (Corsaro \& De Ridder 2014) for the peak bagging analysis and asteroseismic splitting inversion methods to derive the internal rotational profile of the star. The detection of new splittings of mixed modes, more concentrated in the very inner part of the helium core, allowed us to reconstruct the angular velocity profile deeper into the interior of the star and to disentangle the details better than in Paper I: the helium core rotates almost rigidly about 6 times faster than the convective envelope, while part of the hydrogen shell seems to rotate at a constant velocity about 1.15 times lower than the He core. In particular, we studied the internal shear layer between the fast-rotating radiative interior and the slow convective zone and we found that it lies partially inside the hydrogen shell above r0.05Rr \simeq 0.05R and extends across the core-envelope boundary. Finally, we theoretically explored the possibility for the future to sound the convective envelope in the red-giant stars and we concluded that the inversion of a set of splittings with only low-harmonic degree l3l\leq 3, even supposing a very large number of modes, will not allow to resolve the rotational profile of this region in detail.Comment: accepted for publication on Ap

    The Reach-Avoid Problem for Constant-Rate Multi-Mode Systems

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    A constant-rate multi-mode system is a hybrid system that can switch freely among a finite set of modes, and whose dynamics is specified by a finite number of real-valued variables with mode-dependent constant rates. Alur, Wojtczak, and Trivedi have shown that reachability problems for constant-rate multi-mode systems for open and convex safety sets can be solved in polynomial time. In this paper, we study the reachability problem for non-convex state spaces and show that this problem is in general undecidable. We recover decidability by making certain assumptions about the safety set. We present a new algorithm to solve this problem and compare its performance with the popular sampling based algorithm rapidly-exploring random tree (RRT) as implemented in the Open Motion Planning Library (OMPL).Comment: 26 page

    Transferibilidade de locos SSR de Astrocaryum aculeatum Mart. para Astrocaryum vulgare Mart.

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    Este trabalho foi realizado com o objetivo de testar a transferibilidade de locos SSR de Astrocaryum aculeatum para a espécie Astrocaryum vulgare. Para isso, foram aplicados doze locos desenvolvidos para A. aculeatum em seis amostras de DNA obtidas de matrizes de A. vulgare de diferentes procedências. As reações de amplificação foram conduzidas de acordo com o protocolo desenvolvido por Ramos (2012), com pequenas adaptações. Os produtos amplificados foram aplicados em gel de agarose ultra pura a 1,5%, corado com brometo de etídio e submetido à eletroforese horizontal por 1:30 horas. Os perfis dos géis foram fotodocumentados e as imagens armazenadas digitalmente. A transferibilidade dos locos foi avaliada com base na amplificação de produtos e na sua nitidez. Dos doze locos testados, seis apresentaram amplificação satisfatória (visualização do produto), perfazendo uma taxa de transferibilidade de 50%, sugerindo que as espécies possuam alto grau de parentesco. Em todos os locos amplificados não foi detectada a presença de produtos secundários, sendo, portanto, úteis para acessar o genoma de A. vulgare

    Aumento da vida útil pós colheita de pedúnculos de cajueiro anão precoce pela redução da temperatura de armazenamento.

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    Conduziu-se este estudo, realizado no Laboratório de Fisiologia e Tecnologia Pós-Colheita da Embrapa Agroindústria Tropical em Fortaleza (CE), com o objetivo de aumentar o tempo de conservação pós-colheita de pedúnculos dos clones CCP 76 e END 183 de cajueiro anão precoce por meio da redução da temperatura de armazenamento. Foi adotado um fatorial em delineamento inteiramente casualizado, cujos fatores foram os clones e o tempo de armazenamento (0, 5, 10, 15, 20, 25 e 30 dias), avaliados em três repetições. Os frutos, colhidos manualmente, no início da manhã, no Município de Beberibe, Ceará, foram acondicionados em caixas plásticas ainda no campo e transportados para o laboratório onde, acondicionados em bandejas de isopor, foram armazenados a 3,4 ± 0,6ºC e umidade relativa de 85 ± 11%, sob atmosfera modificada. Os parâmetros avaliados foram perda de massa, aparência, cor da película, firmeza da polpa, sólidos solúveis totais, pH, acidez total titulável, SST/ATT, ácido ascórbico, açúcares solúveis totais, antocianinas totais e fenólicos. Os resultados mostraram que os pedúnculos do clone CCP 76 têm vida útil pós-colheita de 18 dias, enquanto o END 183, de 28 dias, ambos com reduzida perda de massa, firmeza e antocianinas totais

    Biogeochemistry of carbon in the Amazonian Floodplains over a 2000-km reach: insights from a process-based model.

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    The influence of Amazonian floodplains on the hydrological, sedimentary, and biogeochemical river budget was investigated over a 2000-km reach. A process-based model relying on the closure of chemical fluxes and isotopic signals was implemented. On average for the whole studied reach, the overall fluxes of carbon associated with mineralization and aquatic photosynthesis were estimated to 35.7 and 15.3 Tg C yr21, respectively. Almost 57% of the carbon sequestrated by photosynthesis comes from aerial sources (flooded forest); the remaining 43% resulted from aquatic sources (va´rzea grasses and phytoplankton). The process rates substantially fluctuate over the annual cycle, depending particularly on the extension of flooded area and on the river?floodplain connectivity. As the river level declines, the drastic decrease of turbidity and the lower supply of carbon substrates promote autotrophy to the detriment of heterotrophy, leading to substantial changes of pH and gaseous equilibria in the river water. The main consequences are (i) the side-chain oxidation of dissolved organic matter leading to the concomitant rises of the carbon to nitrogen atomic ratio and nitrate contents and (ii) the sorption of hydrophobic humic acids, which fractionate 13C and thus lead to 13C-depleted particulate organic matter (fine fraction) compared to remaining dissolved organic matter. As the river flow rises, the heterotrophy prevails over autotrophy and this tends to attenuate the chemical signature imprinted by the latter. The significant contribution of aerial autochthonous sources to the budget of carbon indicates that the fluxes of mineralization are sustained by the net primary production of river corridors. The variable extension of submerged areas defines the proportions of CO2 exported by the river and released to the atmosphere. The rate of CO2 outgassing on the studied reach (18.8 Tg C yr21) represents about 50% of the incoming dissolved inorganic carbon flux. The rate of methane emission is estimated as 2.2 Tg C yr21 and that of denitrification is estimated as 0.87 Tg N yr21, representing 1.5 times the flux of dissolved inorganic nitrogen (DIN) exported by the Amazon River at the station of O ´ bidos (0.64 Tg N yr21)
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