5,309 research outputs found

    The Kinematic Evolution of Strong MgII Absorbers

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    We consider the evolution of strong (W_r(2796) > 0.3A) MgII absorbers, most of which are closely related to luminous galaxies. Using 20 high resolution quasar spectra from the VLT/UVES public archive, we examine 33 strong MgII absorbers in the redshift range 0.3 < z < 2.5. We compare and supplement this sample with 23 strong MgII absorbers at 0.4 < z < 1.4 observed previously with HIRES/Keck. We find that neither equivalent width nor kinematic spread (the optical depth weighted second moment of velocity) of MgII2796 evolve. However, the kinematic spread is sensitive to the highest velocity component, and therefore not as sensitive to additional weak components at intermediate velocities relative to the profile center. The fraction of absorbing pixels within the full velocity range of the system does show a trend of decreasing with decreasing redshift. Most high redshift systems (14/20) exhibit absorption over the entire system velocity range, which differs from the result for low redshift systems (18/36) at the 95% level. This leads to a smaller number of separate subsystems for high redshift systems because weak absorping components tend to connect the stronger regions of absorption. We hypothesize that low redshift MgII profiles are more likely to represent well formed galaxies, many of which have kinematics consistent with a disk/halo structure. High redshift MgII profiles are more likely to show evidence of complex protogalactic structures, with multiple accretion or outflow events. Although these results are derived from measurements of gas kinematics, they are consistent with hierarchical galaxy formation evidenced by deep galaxy surveys.Comment: Accepted to the Astrophysical Journa

    Livre et lecture & Éducation artistique et culturelle

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    Etude publiée par la FILL menée sur 2013 et 2014 sur les projets d\u27action culturelle et artistique centrés sur le livre, réalisés par les structures régionales pour le livre. Ce travail en trois volets a débuté au premier semestre 2013 par le recensement auprès des structures régionales pour le livre membres de la Fill des actions d\u27éducation artistique et culturelle qu\u27elles mènent au profit des élèves de leur région (prioritairement lycéens et apprentis) ou d\u27actions exemplaires menées sur leur territoire. Les deuxième et troisième volets ont été réalisés pour la Fill par Emmanuelle Le Brun (Population & territoire) en 2014, qui a été missionnée pour réaliser, d\u27une part, une étude qualitative de trois dispositifs particulièrement stimulants et rodés portés par des SRL sur trois domaines du secteur - la traduction littéraire avec les ateliers de traduction littéraire d\u27Écla Aquitaine, proposés depuis 2002 aux élèves des lycées aquitains, la critique littéraire, avec le prix littéraire des lycéens et apprentis de la Région Paca, lancé en 2005 et organisé par l\u27ARL Paca, et le patrimoine écrit, avec le projet du Siècle de Gutenberg, action sur trois années à destination de collégiens, coordonnées par Accolad en Franche-Comté à et d\u27autre part, en s\u27appuyant sur ces trois expériences, de proposer des outils communs à partager avec l\u27ensemble des membres de la Fill, pour décrire et évaluer les dispositifs d\u27EAC, afin d\u27en publier un catalogue commun et d\u27en tirer des éléments de renforcement et d\u27évolution au bénéfice des élèves. Les outils sont d\u27ores et déjà testés par certaines SRL et les résultats seront partagés avec les membres de la commission Fill-Élargissement des publics de la Fill

    Biblioteca Pública digital de Huesca: ¿hacia una nueva cultura rural?

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    This article describes the project of a digital public library for the Spanish province of Huesca. Its aims are three: first, creating a public centre for information access; second, establishing a place for information technologies instruction; and, last, facilitating that citizens may create their own digital contentsPresenta la génesis del proyecto de la Biblioteca Pública Digital de Huesca. Se relacionan sus objetivos primordiales: en primer lucar, y fundamentalmente, ser un centro público de acceso a la información; en segundo lugar, constituirse en centro de formación en nuevas tecnologías; y, por último, facilitar a los ciudadanos la difusión de su propia información por medios digitales. (Autor

    Survivin as a therapeutic target in Sonic hedgehog-driven medulloblastoma.

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    Medulloblastoma (MB) is a highly malignant brain tumor that occurs primarily in children. Although surgery, radiation and high-dose chemotherapy have led to increased survival, many MB patients still die from their disease, and patients who survive suffer severe long-term side effects as a consequence of treatment. Thus, more effective and less toxic therapies for MB are critically important. Development of such therapies depends in part on identification of genes that are necessary for growth and survival of tumor cells. Survivin is an inhibitor of apoptosis protein that regulates cell cycle progression and resistance to apoptosis, is frequently expressed in human MB and when expressed at high levels predicts poor clinical outcome. Therefore, we hypothesized that Survivin may have a critical role in growth and survival of MB cells and that targeting it may enhance MB therapy. Here we show that Survivin is overexpressed in tumors from patched (Ptch) mutant mice, a model of Sonic hedgehog (SHH)-driven MB. Genetic deletion of survivin in Ptch mutant tumor cells significantly inhibits proliferation and causes cell cycle arrest. Treatment with small-molecule antagonists of Survivin impairs proliferation and survival of both murine and human MB cells. Finally, Survivin antagonists impede growth of MB cells in vivo. These studies highlight the importance of Survivin in SHH-driven MB, and suggest that it may represent a novel therapeutic target in patients with this disease

    Identification of Single Amino Acid Changes in the Rift Valley Fever Virus Polymerase Core Domain Contributing to Virus Attenuation In Vivo

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    Rift Valley fever (RVF) is an arboviral zoonotic disease affecting many African countries with the potential to spread to other geographical areas. RVF affects sheep, goats, cattle and camels, causing a high rate of abortions and death of newborn lambs. Also, humans can be infected, developing a usually self-limiting disease that can turn into a more severe illness in a low percentage of cases. Although different veterinary vaccines are available in endemic areas in Africa, to date no human vaccine has been licensed. In previous works, we described the selection and characterization of a favipiravir-mutagenized RVFV variant, termed 40Fp8, with potential as a RVF vaccine candidate due to the strong attenuation shown in immunocompromised animal models. Compared to the parental South African 56/74 viral strain, 40Fp8 displayed 7 amino acid substitutions in the L-protein, three of them located in the central region corresponding to the catalytic core of the RNAdependent RNA polymerase (RdRp). In this work, by means of a reverse genetics system, we have analyzed the effect on virulence of these amino acid changes, alone or combined, both in vitro and in vivo. We found that the simultaneous introduction of two changes (G924S and A1303T) in the heterologous ZH548-RVFV Egyptian strain conferred attenuated phenotypes to the rescued viruses as shown in infected mice without affecting virus immunogenicity. Our results suggest that both changes induce resistance to favipiravir likely associated to some fitness cost that could be the basis for the observed attenuation in vivo. Conversely, the third change, I1050V, appears to be a compensatory mutation increasing viral fitness. Altogether, these results provide relevant information for the safety improvement of novel live attenuated RVFV vaccines.info:eu-repo/semantics/publishedVersio

    A catalogue of damped Lyman alpha absorption systems and radio flux densities of the background quasars

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    We present a catalogue of the 322 damped Lyman alpha absorbers taken from the literature. All damped Lyman alpha absorbers are included, with no selection on redshift or quasar magnitude. Of these, 123 are candidates and await confirmation using high resolution spectroscopy. For all 322 objects we catalogue the radio properties of the background quasars, where known. Around 60 quasars have radio flux densities above 0.1 Jy and approximately half of these have optical magnitudes brighter than V = 18. This compilation should prove useful in several areas of extragalactic/cosmological research.Comment: 26 Pages, 12 PS tables, 1 embedded table. Accepted by PASA. Continuously updated online catalogue available at http://www.phys.unsw.edu.au/~sjc/dl

    Hubble Space Telescope Observations of Element Abundances in Low-redshift Damped Lyman-alpha Galaxies and Implications for the Global Metallicity-Redshift Relation

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    Most models of cosmic chemical evolution predict that the mass-weighted mean interstellar metallicity of galaxies should rise with time from a low value 1/30\sim 1/30 solar at z3z \sim 3 to a nearly solar value at z=0z = 0. In the absence of any selection effects, the damped Lyman-alpha absorbers (DLAs) in quasar spectra are expected to show such a rise in global metallicity. However, it has been difficult to determine whether or not DLAs show this effect, primarily because of the very small number of DLA metallicity measurements at low redshifts. In an attempt to put tighter constraints on the low-redshift end of the DLA metallicity-redshift relation, we have observed Zn II and Cr II lines in four DLAs at 0.09<z<0.520.09 < z < 0.52, using the Space Telescope Imaging Spectrograph (STIS) onboard the Hubble Space Telescope (HST). These observations have provided the first constraints on Zn abundances in DLAs with z<0.4z < 0.4. In all the three DLAs for which our observations offer meaningful constraints on the metallicity, the data suggest that the metallicities are much lower than the solar value. These results are consistent with recent imaging studies indicating that these DLAs may be associated with dwarf or low surface brightness galaxies. We combine our results with higher redshift data from the literature to estimate the global mean metallicity-redshift relation for DLAs. We find that the global mean metallicity shows at most a slow increase with decreasing redshift. ...(Please see the paper for the complete abstract).Comment: 56 pages, including 13 figures. Accepted for publication in the Astrophysical Journa

    System for Corrosion Inspection and Monitoring

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    This paper contains has conducted research and analysis on different corrosion identification and monitoring methods to develop an autonomous corrosion inspection system to solve the challenge issued by the University Student Design and Applied Solutions Competition. This challenge is to build an autonomous corrosion detection and monitoring system to help provide new ideas and innovations to the Department of Defense. Using research and stakeholder analysis, this research produced a system to best meet the demands of the competition and determine the best possible solution to the design challenge. Our integrated team used a systems engineering approach to produce the design that will be fielded at the competition in April 2016
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