Browsing Exact and Earth Sciences by Title

Now showing items 1-20 of 3924

    • A 0.8-2.4 μm spectral atlas of active galactic nuclei 

      Riffel, Rogemar André; Rodriguez-Ardila, Alberto; Pastoriza, Miriani Griselda (2006) [Journal article]
      Aims. We present a near-infrared spectral atlas of 47 active galactic nuclei (AGN) of all degrees of activity in the wavelength interval of 0.8–2.4 μm, including the fluxes of the observed emission lines. We analyze the ...

    • 18 Sco : a solar twin rich in refractory and neutron-capture elements, implications for chemical tagging 

      Meléndez, Jorge; Ramírez, Iván; Karakas, Amanda I.; Yong, David; Monroe, TalaWanda Rose; Bedell, Megan; Bergemann, Maria; Asplund, Martin; Maia, Marcelo Tucci; Bean, Jacob L.; Nascimento Júnior, José Dias do; Bazot, Michael; Alves-Brito, Alan; Freitas, Fabrício Catani de; Castro, Matthieu Sébastien (2014) [Journal article]
      We study with unprecedented detail the chemical composition and stellar parameters of the solar twin 18 Sco in a strictly differential sense relative to the Sun. Our study is mainly based on high-resolution (R ∼ 110,000), ...

    • 2006 Whole Earth Telescope observations of GD358 : a new look at the prototype DBV 

      Provencal, Judith L.; Montgomery, Michael Houston; Kanaan Neto, Antonio Nemer; Shipman, Harry L.; Childers, D.; Baran, Andrzej; Kepler, Souza Oliveira; Reed, M. D.; Zhou, Ai-Ying; Eggen, J.; Watson, Todd K.; Winget, Donald Earl; Thompson, S. E.; Riaz, B.; Nitta, Atsuko; Kleinman, Scot James; Crowe, Richard A.; Slivkoff, Jay; Sherard, P.; Purves, Norman G.; Binder, Philippe M.; Knight, R.; Kim, Seung-Lee; Chen, Wen-Ping; Yang, M.; Lin, Hung-Chin; Lin, Chien-Cheng; Chen, C.-W.; Jiang, Xiaojun; Sergeev, A.; Mkrtichian, David; Andreev, M.; Janulis, Rimvydas; Siwak, Michal; Zola, Staszek; Koziel-Wierzbowska, Dorota; Stachowski, G.; Paparo, Margit; Bognár, Zsófia; Handler, Gerald; Lorenz, Denise; Steininger, Bruno; Beck, Paul; Nagel, Thorsten; Kusterer, D.; Hoffman, A.; Reiff, E.; Kowalski, R.; Vauclair, Gérard; Charpinet, Stéphane; Chevreton, Michel; Solheim, Jan-Eric; Pakstiene, Erika; Fraga, Luciano; Dalessio, J. (2009) [Journal article]
      We report on the analysis of 436.1 hr of nearly continuous high-speed photometry on the pulsating DB white dwarf GD358 acquired with the Whole Earth Telescope (WET) during the 2006 international observing run, designated ...

    • 2D nanoporous membrane for cation removal from water : effects of ionic valence, membrane hydrophobicity, and pore size 

      Köhler, Mateus Henrique; Bordin, José Rafael; Barbosa, Marcia Cristina Bernardes (2018) [Journal article]
      Using molecular dynamic simulations, we show that single-layers of molybdenum disulfide (MoS2) and graphene can effectively reject ions and allow high water permeability. Solutions of water and three cations with different ...

    • 2D stellar population and gas kinematics of the inner 1.5 kpc of the post-starburst quasar SDSS J0210−0903 

      Sanmartim, David; Storchi-Bergmann, Thaisa; Brotherton, Mike (2013) [Journal article]
      Post-starburst quasars (PSQs) are hypothesized to represent a stage in the evolution of massive galaxies in which the star formation has been recently quenched due to the feedback of the nuclear activity. In this paper, ...

    • 2D stellar population and gas kinematics of the inner kiloparsec of the post-starburst quasar SDSS J0330−0532 

      Sanmartim, David; Storchi-Bergmann, Thaisa; Brotherton, Mike (2014) [Journal article]
      We have used optical Integral Field Spectroscopy in order to map the star formation history of the inner kiloparsec of the post-starburst quasar (PSQ) J0330−0532 and to map its gas and stellar kinematics as well as the gas ...

    • 3-arylisoxazolyl-5-carboxylic acid and 5-(hydroxymethyl)-3-aryl-2-isoxazoline as molecular platforms for liquid-crystalline materials 

      Tavares, Aline; Livotto, Paolo Roberto; Goncalves, Paulo Fernando Bruno; Merlo, Aloir Antonio (2009) [Journal article]
      A síntese de uma plataforma molecular para materiais líquido-cristalinos derivados do ácido 3-arilisoxazolil-5-carboxílico (1) e do 5-(hidroximetil)-3-aril-2-isoxazolina (2) é descrita. Os intermediários 1 e 2 são obtidos ...

    • 3-Mercaptopropionic, 4-mercaptobenzoic, and oleic acid-capped CdSe quantum dots : interparticle distance, anchoring groups, and surface passivation 

      Santos, José Augusto Lucena dos; Baum, Fabio; Kohlrausch, Emerson Cristofer; Tavares, Fabiele Collovini; Pretto, Tatiane; Santos, Francisco Paulo dos; Ferreira, Jacqueline; Khan, Sherdil; Santos, Marcos José Leite (2019) [Journal article]
      The optoelectronic properties of quantum dots are strongly controlled by the chemical nature of their surface-passivating ligands. In this work, we present the synthesis, characterization, and surface modification of CdSe ...

    • 60 anos da geografia UFRGS 

      Rego, Nelson (2007) [Journal article]

    • Uma abordagem conceitual e fenomenológica dos postulados da física quântica 

      Pereira, Alexsandro Pereira de; Pessoa Junior, Osvaldo; Cavalcanti, Claudio Jose de Holanda; Ostermann, Fernanda (2012) [Journal article]
      No presente trabalho, apresentamos uma discussão sobre os postulados da física quântica a partir de uma “tradução” do formalismo matemático para uma linguagem “operacional” e que envolve uma discussão conceitual e ...

    • Uma abordagem de ensino de reações químicas entre compostos inorgânicos referenciada em mecanismos de reação 

      Nardin, Cláudia Schneiders; Loguercio, Rochele de Quadros; Del Pino, Jose Claudio (2004) [Journal article]
      O ensino do conteúdo relacionado aos compostos inorgânicos se apresenta tradicionalmente, com uma abordagem que pode levar os alunos a uma aprendizagem memorística. Com uma metodologia referenciada na teoria da aprendizagem ...

    • Aborto e coerção sexual : o contexto de vulnerabilidade entre mulheres jovens 

      Pilecco, Flávia Bulegon; Knauth, Daniela Riva; Vigo, Álvaro (2011) [Journal article]
      Neste estudo investigou-se a relação entre a prática do aborto e a declaração de coerção sexual. Os dados foram provenientes do GRAVAD, inquérito domiciliar com amostragem probabilística estratificada, realizado com jovens ...

    • Abra sua janela para o céu 

      Livi, Silvia Helena Becker (1987) [Journal article]
      Resumo não disponível

    • Absolutely continuous invariant mesures for a class of affine interval exchange maps 

      Coelho, Zaqueu; Lopes, Artur Oscar; Rocha, Luiz Fernando Carvalho da (1995) [Journal article]
      We consider a class A of affine interval exchange maps of the interval and we analyse several ergodic properties of the elements of this class, among them the existence of absolutely continuous invariant probability measures. ...

    • Acacia bark residues as filler in polypropylene composites 

      Taflick, Ticiane; Maich, Élida Gonçalves; Ferreira, Laís Dias; Bica, Clara Ismeria Damiani; Rodrigues, Silvia Rosane Santos; Nachtigall, Sonia Marli Bohrz (2015) [Journal article]
      Large amounts of acacia bark residues are produced each day after tannin extraction with hot water, being generally burned. This by-product was chemically characterized and used as filler in polypropylene (PP) composites, ...

    • Accumulation horizons and period adding in optically injected semiconductors lasers 

      Bonatto, Cristian; Gallas, Jason Alfredo Carlson (2007) [Journal article]
      We study the hierarchical structuring of islands of stable periodic oscillations inside chaotic regions in phase diagrams of single-mode semiconductor lasers with optical injection. Phase diagrams display remarkable ...

    • Accuracy of the maximum entropy method 

      Strauss, Federico Maximo (1980) [Journal article]
      Although the maximum entropy method is capable of giving the period of a pure sine wave with very few data points, it is very sensitive to noise. The half power width of a spectral peak obtained by this method is proportional ...

    • Accurate atmospheric parameters at moderate resolution using spectral indices : preliminary application to the MARVELS survey 

      Ghezzi, Luan; Ferreira, Letícia D.; Lorenzo-Oliveira, Diego; Mello, Gustavo Frederico Porto de; Santiago, Basilio Xavier; De Lee, Nathan M.; Lee, Brian L.; Costa, Luiz N. da; Maia, Marcio Antonio Geimba; Ogando, Ricardo L.C.; Wisniewski, J.P.; González Hernández, Jonay I.; Stassun, Keivan G.; Fleming, S.W.; Schneider, D.P.; Mahadevan, Suvrath; Cargile, Phillip A.; Ge, Jian; Pepper, J.; Wang, Ji; Paegert, Martin (2014) [Journal article]
      Studies of Galactic chemical, and dynamical evolution in the solar neighborhood depend on the availability of precise atmospheric parameters (effective temperature Teff, metallicity [Fe/H], and surface gravity log g) for ...

    • Acerca de um mito: o vórtice de Coriolis no ralo da pia 

      Silveira, Fernando Lang da; Axt, Rolando (2000) [Journal article]
      A explicação usual que afirma ser a força de Coriolis responsável pelos redemoinhos ou vórtices em ralos de pias, tanques ou banheiras é questionada. Descrevem-se os experimentos realizados por Shapiro (1962), com o objetivo ...

    • Ácidos naftênicos no petróleo 

      Gruber, Liliane Dailei Almeida; Damasceno, Flaviana Cardoso; Caramão, Elina Bastos; Jacques, Rosângela Assis; Geller, Ana Maria; Campos, Maria Cecília Vaz de (2012) [Journal article]
      Brazilian petroleum is known by its high acidity due to the presence of acidic constituents, especially naphthenic acids (NA). The total characterization of the NA in petrochemical samples has been receiving special attention ...