9,132 research outputs found

    The feminine face of Science

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    Uno de los objetivos fijados en la asignatura Ciencias para el mundo contemporáneo (1º de Bachillerato) es el de superar el escaso interés que siente el alumnado hacia la ciencia. Es necesario para tal fin un cambio en los planteamientos tanto metodológicos como temáticos, respecto a las asignaturas de ciencias tradicionales. Con la intención de contribuir a este cambio se han diseñado actividades en las que confluyen características que podrán ayudar a conseguirlo. En el caso propuesto se escogió una temática controvertida a lo largo de la historia: Mujeres y Ciencia; eligiendo como estrategia de aprendizaje las webquests y publicando en la red las tareas realizadas por el alumnado, todo esto con la finalidad de romper las paredes del aula y hacer extensiva la cultura científica al resto de la comunidad educativa y público en general

    Nonminimal Inflation on the Randall-Sundrum II Brane with Induced Gravity

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    We study an inflation model that inflaton field is non-minimally coupled to the induced scalar curvature on the Randall-Sundrum (RS) II brane. We investigate the effects of the non-minimal coupling on the inflationary dynamics of this braneworld model. Our study shows that the number of e-folds decreases by increasing the value of the non-minimal coupling. We compare our model parameters with the minimal case and also with recent observational data. In comparison with recent observation, we obtain a constraint on the values that the non-minimal coupling attains.Comment: 15 pages, 5 figure

    Control of fluorescence in quantum emitter and metallic nanoshell hybrids for medical applications

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    We study the light emission from quantum emitter and double metallic nanoshell hybrid systems. Quantum emitters act as local sources which transmit their light efficiently due to a double nanoshell near field. The double nanoshell consists a dielectric core and two outer nanoshells

    Retired galaxies: not to be forgotten in the quest of the star formation -- AGN connection

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    We propose a fresh look at the Main Galaxy Sample of the Sloan Digital Sky Survey by packing the galaxies in stellar mass and redshift bins. We show how important it is to consider the emission-line equivalent widths, in addition to the commonly used emission-line ratios, to properly identify retired galaxies (i.e. galaxies that have stopped forming stars and are ionized by their old stellar populations) and not mistake them for galaxies with low-level nuclear activity. We find that the proportion of star-forming galaxies decreases with decreasing redshift in each mass bin, while that of retired galaxies increases. Galaxies with M>1011.5MM_\star > 10^{11.5} M_\odot have formed all their stars at redshift larger than 0.4. The population of AGN hosts is never dominant for galaxy masses larger than 1010M10^{10} M_\odot. We warn about the effects of stacking galaxy spectra to discuss galaxy properties. We estimate the lifetimes of active galactic nuclei (AGN) relying entirely on demographic arguments --- i.e. without any assumption on the AGN radiative properties. We find upper-limit lifetimes of about 1--5 Gyr for detectable AGN in galaxies with masses between 101010^{10}--1012M10^{12} M_\odot. The lifetimes of the AGN-dominated phases are a few 10810^8 yr. Finally, we compare the star-formation histories of star-forming, AGN and retired galaxies as obtained by the spectral synthesis code STARLIGHT. Once the AGN is turned on it inhibits star formation for the next \sim 0.1 Gyr in galaxies with masses around 1010M10^{10} M_\odot, \sim 1 Gyr in galaxies with masses around 1011M10^{11} M_\odot.Comment: accepted for MNRAS figure resolution has been degraded with respect to what will be published in MNRA

    Topological defects and misfit strain in magnetic stripe domains of lateral multilayers with perpendicular magnetic anisotropy

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    Stripe domains are studied in perpendicular magnetic anisotropy films nanostructured with a periodic thickness modulation that induces the lateral modulation of both stripe periods and inplane magnetization. The resulting system is the 2D equivalent of a strained superlattice with properties controlled by interfacial misfit strain within the magnetic stripe structure and shape anisotropy. This allows us to observe, experimentally for the first time, the continuous structural transformation of a grain boundary in this 2D magnetic crystal in the whole angular range. The magnetization reversal process can be tailored through the effect of misfit strain due to the coupling between disclinations in the magnetic stripe pattern and domain walls in the in-plane magnetization configuration
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