125 research outputs found

    z'-band Ground-Based Detection of the Secondary Eclipse of WASP-19b

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    We present the ground-based detection of the secondary eclipse of the transiting exoplanet WASP-19b. The observations were made in the Sloan z'-band using the ULTRACAM triple-beam CCD camera mounted on the NTT. The measurement shows a 0.088\pm0.019% eclipse depth, matching previous predictions based on H- and K-band measurements. We discuss in detail our approach to the removal of errors arising due to systematics in the data set, in addition to fitting a model transit to our data. This fit returns an eclipse centre, T0, of 2455578.7676 HJD, consistent with a circular orbit. Our measurement of the secondary eclipse depth is also compared to model atmospheres of WASP-19b, and is found to be consistent with previous measurements at longer wavelengths for the model atmospheres we investigated.Comment: 20 pages, 10 figures. Published in the ApJ Supplement serie

    Dilatonic AdS-Kerr Solution to AdS/CFT Correspondence

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    We consider the AdS5AdS_5 solution deformed by a non-constant dilaton interpolating between the standard AdS (UV region) and flat boundary background (IR region). We show that this dilatonic solution can be generalized to the case of a non-flat boundaries provided that the metric of the boundaries satisfies the vacuum Einstein field equations. As an example, we describe the case when the four-dimensional boundaries represent the Kerr space-time.Comment: Latex, 8 pages, v.2: a reference added; v.3: a reference added, and two misprints are improved, v.4: final published version, minor corrections, final part is extended and references adde

    Kerr Spinning Particle, Strings, and Superparticle Models

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    A combined model of the Kerr spinning particle and superparticle is considered. The structure of the Kerr geometry is presented in a complex form as being created by a complex source. A natural supergeneralization of this construction is obtained corresponding to a complex "supersource". Peforming a supershift to the Kerr and Kerr-Sen solutions we obtain metrics of supergravity black holes with a nonlinear realization of broken supersymmetry.Comment: minor revision, some grammatical changes and correction of the misprint before eq.(10); 13p., Latex, Talk at the International Seminar "Supersymmetry and quantum field theory" dedicated to the memory of D.V.Volkov, Kharkov, January 199

    Experimental investigation of the initial regime in fingering electrodeposition: dispersion relation and velocity measurements

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    Recently a fingering morphology, resembling the hydrodynamic Saffman-Taylor instability, was identified in the quasi-two-dimensional electrodeposition of copper. We present here measurements of the dispersion relation of the growing front. The instability is accompanied by gravity-driven convection rolls at the electrodes, which are examined using particle image velocimetry. While at the anode the theory presented by Chazalviel et al. describes the convection roll, the flow field at the cathode is more complicated because of the growing deposit. In particular, the analysis of the orientation of the velocity vectors reveals some lag of the development of the convection roll compared to the finger envelope.Comment: 11 pages, 15 figures, REVTEX 4; reference adde

    El álbum poético en portugués y en español: sinergia estética entre palabras e ilustraciones

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    Este estudo procurou problematizar a relação textual que se observa entre a palavra e a imagem em um tipo de texto especialmente concebido para crianças: o álbum poético. Para tal, utilizamos alguns exemplos textuais significativos desse subgênero literário/editorial ainda em emergência tanto em Portugal quanto na Espanha, e propusemos uma definição e uma caracterização baseadas no comentário de sequências poéticas nas quais a ilustração sustenta o conteúdo verbal. Efetivamente, centrando a atenção no álbum poético de potencial recepção infanto-juvenil, sugere-se uma análise de diversos títulos de autoria portuguesa e espanhola, assente em uma leitura dialógica do texto verbal e do visual. A sinergia que se concretiza entre as duas componentes enunciadas alicerça essa nova construção estética que tem, na verdade e na sua essência, a poesia como matriz e, em larga medida, é devedora dos efeitos expressivos da metáfora.This study aimed to discuss the relation between words and images in a type of text especially directed to children: the picture-poetry book. From significant examples of this literary subgenre still emerging in both Portugal and Spain, we propose a definition and characterization based on the review of poetic sequences in which illustrations support the verbal content. By focusing on picture-poetry books potentially aimed for adolescents and children, we present an analysis of several titles by Portuguese and Spanish authors, based on the dialogic reading between verbal and visual texts. The synergy found between these two components creates de foundantions of a new aesthetic construction which, in truth and in essence, has poetry as its matrix and owes its expressive effects to metaphors.Este estudio ha tenido como objetivo discutir la relación textual que existe entre la palabra y la imagen en un tipo texto especialmente creado para niños: el álbum poético. Para ello, utilizamos algunos ejemplos textuales significativos de un subgénero literario en emergencia tanto en Portugal cuanto en España, y hemos propuesto una definición de este subgénero y su caracterización a partir del comentario de secuencias poéticas en las cuales la imagen sustenta el contenido verbal. De hecho, centrando la atención en el álbum poético de potencial recepción infantil y juvenil, proponemos un análisis de diversos títulos de autoría portuguesa y española basado en la lectura dialógica entre el texto verbal y el texto ilustrativo. La sinergia que se establece entre estos dos componentes enunciados facilita una nueva construcción estética que da pie, en su esencia, a un tipo de poesía que, en gran medida, es deudora de los efectos expresivos de la metáfora.CIEC - Centro de Investigação em Estudos da Criança, IE, UMinho (UI 317 da FCT), Portugal. Fundos Nacionais através da FCT (Fundação para a Ciência e a Tecnologia) e cofinanciado pelo Fundo Europeu de Desenvolvimento Regional (FEDER) através do COMPETE 2020 – Programa Operacional Competitividade e Internacionalização (POCI) no âmbito do CIEC (Centro de Investigação em Estudos da Criança, da Universidade do Minho) com a referência POCI-01-0145-FEDER-007562info:eu-repo/semantics/publishedVersio

    A compilation of field surveys on gaseous elemental mercury (GEM) from contrasting environmental settings in Europe, South America, South Africa and China: separating fads from facts

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    Mercury is transported globally in the atmosphere mostly in gaseous elemental form (GEM, Hg0 gas), but still few worldwide studies taking into account different and contrasted environmental settings are available in a single publication. This work presents and discusses data from Argentina, Bolivia, Bosnia and Herzegovina, Brazil, Chile, China, Croatia, Finland, Italy, Russia, South Africa, Spain, Slovenia and Venezuela. We classified the information in four groups: (1) mining districts where this contaminant poses or has posed a risk for human populations and/or ecosystems; (2) cities, where the concentration ofatmospheric mercury could be higher than normal due to the burning of fossil fuels and industrial activities; (3) areas with natural emissions from volcanoes; and (4) pristine areas where no anthropogenic influence was apparent. All the surveys were performed using portable LUMEX RA-915 series atomic absorption spectrometers. The results for cities fall within a low GEM concentration range that rarely exceeds 30 ng m-3, that is, 6.6 times lower than the restrictive ATSDR threshold (200 ng m-3) for chronic exposure to this pollutant. We also observed this behavior in the former mercury mining districts, where few data were above 200 ng m-3.We noted that high concentrations of GEM are localized phenomena that fade away in short distances. However, this does not imply that they do not pose a risk for those working in close proximity to the source. This is the case of the artisanal gold miners that heat the Au–Hg amalgam to vaporize mercury. In this respect, while GEM can be truly regarded as a hazard, because of possible physical–chemical transformations into other species, it is only under these localized conditions, implying exposure to high GEM concentrations, which it becomes a direct risk for humans.Grants CGL2009-13171 and CTM2012-33918 from the Spanish Ministry of Economy and Competitiveness and PII1I09-0142- 4389 from theCastilla-LaMancha (Spain)RegionalGovernment.Published713-7346A. Monitoraggio ambientale, sicurezza e territorioJCR Journalrestricte

    A new Late Agenian (MN2a, Early Miocene) fossil assemblage from Wallenried (Molasse Basin, Canton Fribourg, Switzerland)

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    Excavations of two fossiliferous layers in the Wallenried sand- and marl pit produced a very diversified vertebrate fauna. New material allows the reassessment of the taxonomic position of the ruminant taxa Andegameryx andegaviensis and endemic Friburgomeryx wallenriedensis. An emended diagnosis for the second species is provided and additional material of large and small mammals, as well as ectothermic vertebrates, is described. The recorded Lagomorpha show interesting morphological deviations from other Central European material, and probably represent a unique transitional assemblage with a co-occurrence of Titanomys, Lagopsis and Prolagus. Rodentia and Eulipotyphla belong to typical and well-known species of the Agenian of the Swiss Molasse Basin. Abundant small mammal teeth have allowed us to pinpoint the biostratigraphic age of Wallenried to late MN2a. The biostratigraphic age conforms to data derived from the charophyte assemblages and confirms the oldest occurrence of venomous snake fangs. The palaeoenvironmental context is quite complex. Sedimentary structures and fauna (fishes, frogs, salamanders, ostracods) are characteristic for a humid, lacustrine environment within a flood plain system

    The 2016 Feb 19 outburst of comet 67P/CG: an ESA Rosetta multi-instrument study

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    On 2016 Feb 19, nine Rosetta instruments serendipitously observed an outburst of gas and dust from the nucleus of comet 67P/Churyumov-Gerasimenko. Among these instruments were cameras and spectrometers ranging from UV over visible to microwave wavelengths, in situ gas, dust and plasma instruments, and one dust collector. At 09:40 a dust cloud developed at the edge of an image in the shadowed region of the nucleus. Over the next two hours the instruments recorded a signature of the outburst that significantly exceeded the background. The enhancement ranged from 50 per cent of the neutral gas density at Rosetta to factors >100 of the brightness of the coma near the nucleus. Dust related phenomena (dust counts or brightness due to illuminated dust) showed the strongest enhancements (factors >10). However, even the electron density at Rosetta increased by a factor 3 and consequently the spacecraft potential changed from ∼−16 V to −20 V during the outburst. A clear sequence of events was observed at the distance of Rosetta (34 km from the nucleus): within 15 min the Star Tracker camera detected fast particles (∼25 m s−1) while 100 μm radius particles were detected by the GIADA dust instrument ∼1 h later at a speed of 6 m s−1. The slowest were individual mm to cm sized grains observed by the OSIRIS cameras. Although the outburst originated just outside the FOV of the instruments, the source region and the magnitude of the outburst could be determined
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