761 research outputs found

    Publicidad contextual: Una alternativa de la eficacia en Internet

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    Proponemos analizar la “publicidad interactiva” en España y, de forma particular del formato denominado “publicidad contextual” o de “enlaces patrocinados” (entre otros, sus aspectos funcionales y operativos). La velocidad de los procesos de esta nueva forma de comunicación y la falta de estudios relacionados con el tema, invita a discutir y profundizar en los aspectos singulares que pudiera aportar Internet como herramienta en la gestión del marketing, en esa búsqueda constante por contactar con el público objetivo determinado. La accesibilidad que caracteriza a este formato -se le podría denominar como “democrático”, ya que no necesita grandes inversiones para alcanzar una elevada efectividad-, y su transparencia y rapidez en la evaluación de los resultados lo hacen interesante para cualquier organización que considere estratégica la utilización de Internet como medio para sus comunicaciones comerciales. La inclusión del desarrollo de un proyecto real, además de ser un apoyo explicativo a nuestro discurso, permite evaluar en sus aspectos cuantitativos y cualitativos las características de nuestro objeto de estudio.We aim to analyse “interactive advertising” in Spain, particularly the format known as “contextual advertising” or “sponsored links” (including their functional and operative aspects). The speed of processes in this new form of communication and the absence of studies on the matter invite discussion, examining the special features that Internet could contribute as a marketing management tool, in that constant striving to contact a given target public. The accessibility that characterises this format -it could be called “democratic” since it can be highly effective without requiring heavy investment- and its transparency and speed in assessing results make it interesting for any organisation that considers Internet a strategic medium for commercial communication. By including the development of a real project, apart from backing up our dissertation, we are able to assess the quantitative and qualitative aspects of our subject matter

    Aprender a reconocer la manipulación en informativos de TV : el caso de Telemadrid, 2003-2012

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    Las noticias en formato audiovisual inundan las distintas pantallas, y en muchas ocasiones como elaboraciones y contenidos que sobrepasan los límites de la función informativa hacia la propaganda, la voluntad comercial o la opinión. Una sociedad democrática idealmente sana debería estar formada por ciudadanos capaces de seleccionar los mensajes de su interés, analizarlos y evaluar sus contenidos, diferenciando entre los que responden al derecho a la libertad de información y los que pretenden otras intenciones. Estos son algunos de los objetivos de la iniciativa para la alfabetización mediática e informacional (o, en sus siglas en inglés, MIL, Media Information Literacy). El establecimiento de la agenda, el estudio del énfasis, la enunciación o la reiteración de enunciados no son las únicas fórmulas de manipulación de los noticieros audiovisuales diarios. A algunos vicios periodísticos ya conocidos hay que añadir los procedimientos manipuladores que corresponden a las técnicas del montaje audiovisual. Partiendo de la premisa de que cualquier forma de construcción es manipulable, este trabajo propone un debate sobre las estructuras de montaje audiovisual a distintos niveles -programación, articulación de la escaleta de noticias, montaje-, con la finalidad de poner de relieve que, en muchas ocasiones, la mera formación en análisis de textos audiovisuales no es suficiente para desvelar prácticas de manipulación deshonesta en la construcción de la noticia y que, por lo tanto, es necesario que la alfabetización incluya un adiestramiento en las prácticas de producción profesionales, que capacite para detectar la intención manipulativa en el propio proceso de escritura audiovisual. Se utilizan como ejemplo, en este caso negativo, noticias y tratamientos informativos que Telemadrid ha mostrado en sus pantallas durante la década 2003-2012

    The cosmic evolution of the spatially-resolved star formation rate and stellar mass of the CALIFA survey

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    We investigate the cosmic evolution of the absolute and specific star formation rate (SFR, sSFR) of galaxies as derived from a spatially-resolved study of the stellar populations in a set of 366 nearby galaxies from the CALIFA survey. The analysis combines GALEX and SDSS images with the 4000 break, H_beta, and [MgFe] indices measured from the datacubes, to constrain parametric models for the SFH, which are then used to study the cosmic evolution of the star formation rate density (SFRD), the sSFR, the main sequence of star formation (MSSF), and the stellar mass density (SMD). A delayed-tau model, provides the best results, in good agreement with those obtained from cosmological surveys. Our main results from this model are: a) The time since the onset of the star formation is larger in the inner regions than in the outer ones, while tau is similar or smaller in the inner than in the outer regions. b) The sSFR declines rapidly as the Universe evolves, and faster for early than for late type galaxies, and for the inner than for the outer regions of galaxies. c) SFRD and SMD agree well with results from cosmological surveys. At z< 0.5, most star formation takes place in the outer regions of late spiral galaxies, while at z>2 the inner regions of the progenitors of the current E and S0 are the major contributors to SFRD. d) The inner regions of galaxies are the major contributor to SMD at z> 0.5, growing their mass faster than the outer regions, with a lookback time at 50% SMD of 9 and 6 Gyr for the inner and outer regions. e) The MSSF follows a power-law at high redshift, with the slope evolving with time, but always being sub-linear. f) In agreement with galaxy surveys at different redshifts, the average SFH of CALIFA galaxies indicates that galaxies grow their mass mainly in a mode that is well represented by a delayed-tau model, with the peak at z~2 and an e-folding time of 3.9 Gyr.Comment: 23 pages, 16 figures, 6 tables, accepted for publication in Astronomy & Astrophysics. *Abridged abstract

    EFFECT OF DISSOLVED ORGANIC MATTER ON COPPER BIOAVAILABILITY TO A COASTAL DINOFLAGELLATE

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    Metal complexation by dissolved organic matter (DOM) is considered to decrease metal bioavailability by lowering the free metal ion concentration, therefore protecting organisms from the deleterious effects of metals (Campbell et al., 2002). In coastal lagoons like Mar Menor, with high terrestrial influence and low exchange with open sea, the levels of both DOM and metals are one or two orders of magnitude higher than in open-waters. In order to verify the free ion activity model (FIAM), copper internalization by Prorocentrum micans, a cosmopolitan dinoflagellate also present in the Mar Menor, was tested in the absence and presence of two types of DOM, commercially available fulvic acids from riverine origin (SRFA) and coastal DOM obtained by ultrafiltration (UF-DOM). The microalgae were exposed to artificial sea water enriched with increasing amounts of Cu65 isotope, at levels from 5 to 100 nM Cu, solely and in combination with DOM. After one-hour exposure, samples were centrifuged and washed and pellets were digested with nitric acid at 90ºC, following Sánchez-Marín et al (2010) and Croteau and Luoma (2005). In parallel, careful measurements of metal complexation by anodic stripping voltammetry (ASV) were performed and total Cu concentrations were measured by ICP-MS. Preliminary results show that copper internalization by the microalgae increases linearly as a function of labile Cu, both in the absence and presence of DOM, in agreement with FIAM and with labile Cu measurements performed by ASV. Future work might include testing the influence of competing metals, such as Pb or Zn, on Cu internalization, and to study Cu bioavailability in natural samples collected in the Mar Menor, in order to shed light into the factors that control Cu bioavailability in coastal lagoons

    The spatially resolved star formation history of CALIFA galaxies: Cosmic time scales

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    This paper presents the mass assembly time scales of nearby galaxies observed by CALIFA at the 3.5m telescope in Calar Alto. We apply the fossil record method of the stellar populations to the complete sample of the 3rd CALIFA data release, with a total of 661 galaxies, covering stellar masses from 108.4^{8.4} to 1012^{12} M_{\odot} and a wide range of Hubble types. We apply spectral synthesis techniques to the datacubes and process the results to produce the mass growth time scales and mass weighted ages, from which we obtain temporal and spatially resolved information in seven bins of galaxy morphology and six bins of stellar mass (M_{\star}) and stellar mass surface density (Σ\Sigma_{\star}). We use three different tracers of the spatially resolved star formation history (mass assembly curves, ratio of half mass to half light radii, and mass-weighted age gradients) to test if galaxies grow inside-out, and its dependence with galaxy stellar mass, Σ\Sigma_{\star}, and morphology. Our main results are as follows: (a) The innermost regions of galaxies assemble their mass at an earlier time than regions located in the outer parts; this happens at any given M_{\star}, Σ\Sigma_{\star}, or Hubble type, including the lowest mass systems. (b) Galaxies present a significant diversity in their characteristic formation epochs for lower-mass systems. This diversity shows a strong dependence of the mass assembly time scales on Σ\Sigma_{\star} and Hubble type in the lower-mass range (108.4^{8.4} to 1010.4^{10.4}), but a very mild dependence in higher-mass bins. (c) All galaxies show negative \langlelog ageM\rangle_{M} gradients in the inner 1 HLR. The profile flattens with increasing values of Σ\Sigma_{\star}. There is no significant dependence on M_{\star} within a particular Σ\Sigma_{\star} bin, except for the lowest bin, where the gradients becomes steeper.Comment: 15 pages, 13 figures, 3 tables, accepted for publication in Astronomy & Astrophysics. *Abridged abstract

    Una propuesta que facilita el uso eficaz de los libros de texto a los futuros profesores de matemáticas

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    En este trabajo se presentan los primeros resultados de una experiencia piloto desarrollada en el marco del Máster de Formación de Profesores de Matemáticas de Secundaria, Bachillerato e Idiomas (MFP) de la Universidad Rey Juan Carlos de Madrid (URJC), en la que se trata de obtener información, a través de cuestionarios diseñados a tal efecto por el equipo de investigadores que presenta esta propuesta, sobre qué conocimientos matemáticos específicos necesita un profesor de matemáticas para usar de manera eficaz en el aula el libro de texto. Como punto de partida, y a través del trabajo colaborativo de los autores de la propuesta aquí presentada, se ha diseñado un conjunto de ítems para analizar minuciosamente los contenidos de una Unidad Didáctica de un libro de texto

    The spatially-resolved star formation histories of CALIFA galaxies: Implications for galaxy formation

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    This paper presents the spatially resolved star formation history (SFH) of nearby galaxies with the aim of furthering our understanding of the different processes involved in the formation and evolution of galaxies. To this end, we apply the fossil record method of stellar population synthesis to a rich and diverse data set of 436 galaxies observed with integral field spectroscopy in the CALIFA survey. The sample covers a wide range of Hubble types, with stellar masses ranging from M109M_\star \sim 10^9 to 7×1011M7 \times 10^{11} M_\odot. Spectral synthesis techniques are applied to the datacubes to retrieve the spatially resolved time evolution of the star formation rate (SFR), its intensity (ΣSFR\Sigma_{\rm SFR}), and other descriptors of the 2D-SFH in seven bins of galaxy morphology (E, S0, Sa, Sb, Sbc, Sc, and Sd), and five bins of stellar mass. Our main results are: a) Galaxies form very fast independently of their current stellar mass, with the peak of star formation at high redshift (z>2z > 2). Subsequent star formation is driven by MM_\star and morphology, with less massive and later type spirals showing more prolonged periods of star formation. b) At any epoch in the past the SFR is proportional to MM_\star, with most massive galaxies having the highest absolute (but lowest specific) SFRs. c) While nowadays ΣSFR\Sigma_{\rm SFR} is similar for all spirals, and significantly lower in early type galaxies (ETG), in the past ΣSFR\Sigma_{\rm SFR} scales well with morphology. The central regions of today's ETGs are where ΣSFR\Sigma_{\rm SFR} reached the highest values (>103M> 10^3 \,M_\odot\,Gyr1^{-1}\,pc2^{-2}), similar to those measured in high redshift star forming galaxies. d) The evolution of ΣSFR\Sigma_{\rm SFR} in Sbc systems matches that of models for Milky-Way-like galaxies, suggesting that the formation of a thick disk may be a common phase in spirals at early epochs.Comment: 21 pages, 11 figures, 1 table, accepted for publication in Astronomy & Astrophysics, abstract abridged for arXiv submissio
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