4,201 research outputs found

    Applications of Green Walls in Urban Design

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    Green walls are a choice towards achieving sustainable urban rehabilitation, due to the lack of free space in the consolidated urban fabric. Nowadays, green walls are considered to be an innovation in the fields of ecology, horticulture or buildings. Nevertheless, in the domain of urban design, they are still surprising and unexpected ideas. Thus, this research aims to reflect on green walls as a feature in urban design and rehabilitation, identifying the advantages of their utilization as an enhancement of the quality of city’s image, especially in dense urban areas. It aims to demonstrate some practical applications of green walls in urban design proposals, showing model solutions and their real application in several architectural examples.info:eu-repo/semantics/publishedVersio

    A search for magnetic fields on central stars in planetary nebulae

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    One of the possible mechanisms responsible for the panoply of shapes in planetary nebulae is the presence of magnetic fields that drive the ejection of ionized material during the proto-planetary nebula phase. Therefore, detecting magnetic fields in such objects is of key importance for understanding their dynamics. Still, magnetic fields have not been detected using polarimetry in the central stars of planetary nebulae. Circularly polarized light spectra have been obtained with the Focal Reducer and Low Dispersion Spectrograph at the Very Large Telescope of the European Southern Observatory and the Intermediate dispersion Spectrograph and Imaging System at the William Herschel Telescope. Nineteen planetary nebulae spanning very different morphology and evolutionary stages have been selected. Most of central stars have been observed at different rotation phases to point out evidence of magnetic variability. In this paper, we present the result of two observational campaigns aimed to detect and measure the magnetic field in the central stars of planetary nebulae on the basis of low resolution spectropolarimetry. In the limit of the adopted method, we can state that large scale fields of kG order are not hosted on the central star of planetary nebulae.Comment: Paper accepted to be published in Astronomy and Astrophysics on 20/01/201

    The Spitzer South Pole Telescope Deep Field Survey: Linking galaxies and halos at z=1.5

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    We present an analysis of the clustering of high-redshift galaxies in the recently completed 94 deg2^2 Spitzer-SPT Deep Field survey. Applying flux and color cuts to the mid-infrared photometry efficiently selects galaxies at z1.5z\sim1.5 in the stellar mass range 10101011M10^{10}-10^{11}M_\odot, making this sample the largest used so far to study such a distant population. We measure the angular correlation function in different flux-limited samples at scales >6>6^{\prime \prime} (corresponding to physical distances >0.05>0.05 Mpc) and thereby map the one- and two-halo contributions to the clustering. We fit halo occupation distributions and determine how the central galaxy's stellar mass and satellite occupation depend on the halo mass. We measure a prominent peak in the stellar-to-halo mass ratio at a halo mass of log(Mhalo/M)=12.44±0.08\log(M_{\rm halo} / M_\odot) = 12.44\pm0.08, 4.5 times higher than the z=0z=0 value. This supports the idea of an evolving mass threshold above which star formation is quenched. We estimate the large-scale bias in the range bg=24b_g=2-4 and the satellite fraction to be fsat0.2f_\mathrm{sat}\sim0.2, showing a clear evolution compared to z=0z=0. We also find that, above a given stellar mass limit, the fraction of galaxies that are in similar mass pairs is higher at z=1.5z=1.5 than at z=0z=0. In addition, we measure that this fraction mildly increases with the stellar mass limit at z=1.5z=1.5, which is the opposite of the behavior seen at low-redshift.Comment: 32 pages, 22 figures. Published in MNRA
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