5,537 research outputs found

    Imagery and long-slit spectroscopy of the Polar-Ring Galaxy AM2020-504

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    Interactions between galaxies are very common. There are special kinds of interactions that produce systems called Polar Ring Galaxies (PRGs), composed by a lenticular, elliptical, or spiral host galaxy, surrounded by a ring of stars and gas, orbiting in an approximately polar plane. The present work aims to study AM2020-504, a PRG with an elliptical host galaxy, and a narrow and well defined ring, probably formed by accretion of material from a donor galaxy, collected by the host galaxy. Our observational study was based on BVRI broad band imagery as well as longslit spectroscopy in the wavelenght range 4100--8600\AA, performed at the 1.6m telescope at the Observat\'orio do Pico dos Dias (OPD), Brazil. We estimated a redshift of z= 0.01683, corresponding a heliocentric radial velocity of 5045 +/-23 km/s. The (B-R) color map shows that the ring is bluer than the host galaxy, indicating that the ring is a younger structure. Standard diagnostic diagrams were used to classify the main ionizing source of selected emission-line regions (nucleus, host galaxy and ring). It turns out that the ring regions are mainly ionized by massive stars while the nucleus presents AGN characteristics. Using two empirical methods, we found oxygen abundances for the HII regions located in the ring in the range 12+log(O/H)=8.3-8.8 dex, the presence of an oxygen gradient across the ring, and that AM2020-504 follows the metallicity-luminosity relation of spiral galaxies. These results support the accretion scenario for this object and rules out cold accretion as source for the HI gas in the polar ring

    Statistical stability of equilibrium states for interval maps

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    We consider families of multimodal interval maps with polynomial growth of the derivative along the critical orbits. For these maps Bruin and Todd have shown the existence and uniqueness of equilibrium states for the potential ϕt:x↩−tlog⁥∣Df(x)∣\phi_t:x\mapsto-t\log|Df(x)|, for tt close to 1. We show that these equilibrium states vary continuously in the weak∗^* topology within such families. Moreover, in the case t=1t=1, when the equilibrium states are absolutely continuous with respect to Lebesgue, we show that the densities vary continuously within these families.Comment: More details given and the appendices now incorporated into the rest of the pape

    A frictionless microswimmer

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    We investigate the self-locomotion of an elongated microswimmer by virtue of the unidirectional tangential surface treadmilling. We show that the propulsion could be almost frictionless, as the microswimmer is propelled forward with the speed of the backward surface motion, i.e. it moves throughout an almost quiescent fluid. We investigate this swimming technique using the special spheroidal coordinates and also find an explicit closed-form optimal solution for a two-dimensional treadmiler via complex-variable techniques.Comment: 6 pages, 4 figure

    Acquired-Transient Factor X Deficiency in a Teenager with Extensive Burns

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    Acquired factor X deficiency is an extremely rare situation. It has shown to be associated with systemic amyloidosis, respiratory mycoplasma infection, factor X inhibitors, antiphospholipid antibodies, vitamin K defi ciency/liver disease as well as the use of certain medications (meropenem, valproic acid). The pathogenesis and transient nature of this deficit remain poorly understood. The authors describe the case of a teenager hospitalised for extensive burns that developed active bleeding after removal of central venous catheter. He was diagnosed with transient factor X deficiency. Normalisation of coagulation status and factor X levels occurred spontaneously 10 days after the bleeding episode

    The governance of formal university–industry interactions: understanding the rationales for alternative models

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    This article develops a conceptual framework to explain the economic rationale underpinning the choice of different modes of governance of formal university–industry interactions: personal contractual interactions, where the contract regulating the collaboration involves a firm and an individual academic researcher, and institutional interactions, where the relationship between the firm and the academic is mediated by the university. Although institutional interactions, for numerous reasons, have become more important, both governance modes are currently being implemented. We would argue that they have some important specificities that need to be understood if university–industry knowledge transfer is to be managed effectively and efficiently

    Efeito de årea e densidade de årvores sobre a probabilidade de ocupação de manchas florestais no Pantanal por corujas pretas (Strix huhula).

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    A fragmentação e a degradação de habitats estĂŁo entre os principais problemas para a conservação da biodiversidade. No Pantanal, muitas vezes considera do o ecossistema mais preservado do Brasil, a criação de gado bovino hĂĄ mais de dois sĂ©culos na regiĂŁo se baseia em prĂĄticas de manejo da vegetação utilizadas de formas diversas, em especial o uso do fogo. Entretanto, os efeitos de distĂșrbios crĂŽnicos sobre a estrutura de habitats e seus efeitos sobre as espĂ©cies nĂŁo tem sido estudados. NĂłs utilizamos a modelagem de ocupação para avaliar os efeitos da estrutura de habitats forestais sobre a coruja preta, com base em amostragem em 36 pontos localizados na porção oeste da NhecolĂąndia, Pantanal, CorumbĂĄ, MS, entre fevereiro e junho de 2013. O melhor modelo de probabilidade de ocupação inclui tanto a ĂĄrea das manchas florestais qunanto a densidade de ĂĄrevores maiorres que 50 cm de circunferencia ĂĄ altura do peito. Os resultados indicam que distĂșrbios crĂŽnicos podem estar afetando a estrutura de habitats, por interferencia na dinamica da vegetação, e consequentemente afetando espĂ©cies da fauna associadas Ă  habitats florestais, como a coruja preta

    Disorder effects at low temperatures in La_{0.7-x}Y_{x}Ca_{0.3}MnO_{3} manganites

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    With the aim of probing the effect of magnetic disorder in the low-temperature excitations of manganites, specific-heat measurements were performed in zero field, and in magnetic fields up to 9 T in polycrystalline samples of La_{0.7-x}Y_{x}Ca_{0.3}MnO_{3}, with Y concentrations x=0, 0.10, and 0.15. Yttrium doping yielded the appearance of a cluster-glass state, giving rise to unusual low-temperature behavior of the specific-heat. The main feature observed in the results is a strong enhancement of the specific-heat linear term, which is interpreted as a direct consequence of magnetic disorder. The analysis was further corroborated by resistivity measurements in the same compounds.Comment: 9 pages, 2 figure

    Travel of studies: cities of JoĂŁo Pessoa, Maceio, Natal and Recife: a look on the urban space and brazilian architectural production

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    Ponencia presentada a Session 8: Dimensiones psicosociales de la arquitectura y el urbanismo / Psycological dimensions of architecture and planningThis article aims to present the methodology and the final results of the elective course “Travel of Studies” which belongs to the new pedagogical project from the Architecture and Urbanism course at the University Federal of Pernambuco. It was offered for the first time in 2013.The discipline was organized to occur in four long weekends through visits of four capitals of the Northeast of Brazil: Recife, João Pessoa, Natal and Maceió. The purpose was to allow the students to apprehend the cities through four axis: intervention in historical center (axis 1), production of urban space (axis 2), production of coastline space (axis 3) and contemporary architecture (axis 4). After the four visits were complete, we prepared a poster with the comparison of the cities based on the identification of the similarities and differences of each axis we have studied
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