421 research outputs found

    The star formation rate cookbook at 1 < z < 3: Extinction-corrected relations for UV & [OII]{\lambda}3727 luminosities

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    We use a spectroscopic sample of 286 star-forming galaxies (SFGs) at 1<z<3 from the GMASS survey to study different star formation rate (SFR) estimators. Infrared (IR) data are used to derive empirical calibrations to correct ultraviolet (UV) and [OII]{\lambda}3727 luminosities for dust extinction and dust-corrected estimates of SFR. In the selection procedure we fully exploit the available spectroscopic information. On the basis of three continuum indices, we are able to identify and exclude from the sample galaxies in which old stellar populations might bring a non-negligible contribution to IR luminosity (LIR) and continuum reddening. Using Spitzer-MIPS and Herschel-PACS data we derive LIR for two-thirds of our sample. The LIR/LUV ratio is used as a probe of effective attenuation (AIRX) to search for correlations with continuum and spectroscopic features. The relation between AIRX and UV continuum slope ({\beta}) was tested for our sample and found to be broadly consistent with the literature results at the same redshift, though with a larger dispersion with respect to UV-selected samples. We find a correlation between the rest-frame equivalent width (EW) of the [OII]{\lambda}3727 line and {\beta}, which is the main result of this work. We therefore propose the [OII]{\lambda}3727 line EW as a dust attenuation probe and calibrate it through AIRX, though the assumption of a reddening curve is still needed to derive the actual attenuation towards the [OII]{\lambda}3727 line. We tested the issue of differential attenuation towards stellar continuum and nebular emission: our results are in line with the traditional prescription of extra attenuation towards nebular lines. A set of relations is provided that allows the recovery of the total unattenuated SFR from UV and [OII]{\lambda}3727 luminosities. (Abridged)Comment: Accepted for publication in A&A; 20 pages, 19 figures, 5 table

    On the nature of the ISO-selected sources in the ELAIS S2 region

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    We have studied the optical, near-IR and radio properties of a complete sample of 43 sources detected at 15-micron in one of the deeper ELAIS repeatedly observed region. The extragalactic objects in this sample have 15-micron flux densities in the range 0.4-10 mJy, where the source counts start diverging from no evolution models. About 90% of the sources (39 out of 43) have optical counterparts brighter than I=21 mag. Eight of these 39 sources have been identified with stars on the basis of imaging data, while for another 22 sources we have obtained optical spectroscopy, reaching a high identification percentage (30/43, ~70%). All but one of the 28 sources with flux density > 0.7 mJy are identified. Most of the extragalactic objects are normal spiral or starburst galaxies at moderate redshift (z_med~0.2); four objects are Active Galactic Nuclei. We have used the 15-micron, H_alpha and 1.4-GHz luminosities as indicators of star-formation rate and we have compared the results obtained in these three bands. While 1.4-GHz and 15-micron estimates are in good agreement, showing that our galaxies are forming stars at a median rate of ~40 Mo/yr, the raw H_alpha-based estimates are a factor ~5-10 lower and need a mean correction of ~2 mag to be brought on the same scale as the other two indicators. A correction of ~2 mag is consistent with what suggested by the Balmer decrements H_alpha/H_beta and by the optical colours. Moreover, it is intermediate between the correction found locally for normal spirals and the correction needed for high-luminosity 15-micron objects, suggesting that the average extinction suffered by galaxies increases with infrared luminosity.Comment: 19 pages, 11 figures (3 in JPEG format), MNRAS, accepte

    O PARADIGMA DA MODERNIDADE E A SITUAÇÃO DE ANOMIA DOS ESQUECIDOS

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    ABSTRACT: this article seeks to relate the anomic society described by the sociologist Robert King Merton with the legal paradigm of modernity, adopted in Latin American countries since colonization. The aim of this study is to rethink the law beyond legal technicality, in order to reconnect this field of knowledge with other sources of knowledge, such as philosophy and anthropology. We work with Merton's concept of anomie, since in anomic society the members of the less favored classes will always be conceived as dangerous and worthy of state repression. As for the 1988 Constitution, there is a criticism, since it has institutionalized meritocracy, without guaranteeing the initial need for equal opportunities. It is concluded that there is a need to typify new rights and subjects of law through the reformulation of the legal paradigm of modernity, as happened with the Constitutions of Ecuador of 2008 and Bolivia of 2009, in order to guarantee the cultural goals for all the population.Este artículo busca relacionar la sociedad anémica descrita por el sociólogo Robert King Merton con el paradigma legal de la modernidad, adoptado en los países latinoamericanos desde la colonización. El objetivo de este estudio es repensar el derecho más allá del tecnicismo jurídico, con el fin de reconectar este campo del conocimiento con otras fuentes de conocimiento, como la filosofía y la antropología. Trabajamos con el concepto de anomía de Merton, ya que en la sociedad anómica los miembros de las clases menos favorecidas siempre serán concebidos como peligrosos y dignos de la represión estatal. En cuanto a la Constitución de 1988, se hace una crítica, ya que institucionalizó la meritocracia, sin garantizar a los más necesitados las oportunidades iniciales. Se concluye que es necesario tipificar nuevos derechos y materias de derecho a través de la reformulación del paradigma jurídico de la modernidad, como sucedió con las Constituciones de Ecuador de 2008 y Bolivia de 2009, con el fin de garantizar objetivos culturales para toda la población.Este artigo busca relacionar a sociedade anômica descrita pelo sociólogo Robert King Merton com o paradigma jurídico da modernidade, adotado nos países latino-americanos desde a colonização. O objetivo deste estudo é repensar o direito para além da tecnicidade jurídica, a fim de reaproximar esse campo do saber com outras fontes de conhecimento, como a filosofia e a antropologia. Trabalha-se com o conceito de anomia de Merton, visto que na sociedade anômica os membros das classes menos favorecidas serão sempre concebidos como perigosos e dignos de repressão estatal. Quanto à Constituição de 1988, faz-se uma crítica, posto que institucionalizou a meritocracia, sem garantir aos mais necessitados a igualdade de oportunidades iniciais. Conclui-se que há a necessidade de se tipificar novos direitos e sujeitos de direito por meio da reformulação do paradigma jurídico da modernidade, como aconteceu com as Constituições do Equador de 2008 e da Bolívia de 2009, de forma a garantir as metas culturais para toda a população

    Organ Neuroprosthetics: Connecting Transplanted and Artificial Organs with the Nervous System

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    Implantable neural interfaces with the central and peripheral nervous systems are currently used to restore sensory, motor, and cognitive functions in disabled people with very promising results. They have also been used to modulate autonomic activities to treat diseases such as diabetes or hypertension. Here, this study proposes to extend the use of these technologies to (re-)establish the connection between new (transplanted or artificial) organs and the nervous system in order to increase the long-term efficacy and the effective biointegration of these solutions. In this perspective paper, some clinically relevant applications of this approach are briefly described. Then, the choices that neural engineers must implement about the type, implantation location, and closed-loop control algorithms to successfully realize this approach are highlighted. It is believed that these new "organ neuroprostheses" are going to become more and more valuable and very effective solutions in the years to come

    PALEORADIOLOGICAL STUDY ON TWO INFANTS DATED TO THE 17th AND 18th CENTURIES

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    During an excavation campaign in the Church of the Conversion of Saint Paul in Roccapelago (North Italy), a hidden crypt was discovered, which yielded the remains of more than 400 individuals. The crypt was used as a cemetery by the inhabitants of the village of Roccapelago between the 16th and 18th centuries. Along the north side of the crypt, an area apparently separated from the rest of the burials was found, bordered by stones, where several burials of newborns and infants were concentrated. From here, five fabric rolls containing bones were recovered, and it was decided not to carry out destructive analyses, allocating the two best examples to a thorough radiological investigation to try to define the type of burial and the complete biological profile of the infant. The two rolls, subjects of this study, can be dated archaeologically between the 17th and 18th centuries. CT analysis shows a varied group of bones with a fairly good state of conservation. The paleoradiological study carried out had the primary objective of avoiding the destruction of the two rolls, ensuring their conservation; but at the same time, providing essential data to understand their nature, defining the biological profile and the type of deposition

    Type 2 Quasars at the heart of dust-obscured galaxies (DOGs) at high z

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    Dust‐obscured galaxies (DOGs) represent a recently‐discovered, intriguing class of mid‐IR luminous sources at high redshifts. Evidence is mounting that DOGs (selected on the basis of extreme optical/mid‐IR color cut and high mid‐IR flux level) may represent systems caught in the process of host galaxy formation and intense SMBH growth. Here we report the results of an X‐ray spectroscopic survey aimed at studying the X‐ray properties of these sources and establishing the fraction of Type 2 quasars among them

    High-z X-ray Obscured Quasars in Galaxies with Extreme Mid-IR/Optical Colors

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    Extreme Optical/Mid‐IR color cuts have been used to uncover a population of dust‐enshrouded, mid‐IR luminous galaxies at high redshifts. Several lines of evidence point towards the presence of an heavily absorbed, possibly Compton‐thick quasar at the heart of these systems. Nonetheless, the X‐ray spectral properties of these intriguing sources still remain largely unexplored. Here we present an X‐ray spectroscopic study of a large sample of 44 extreme dust‐obscured galaxies (EDOGs) with F_(24μm)/F_R > 2000 and F_(24μm) > 1.3 mJy selected from a 6 deg^2 region in the SWIRE fields. The application of our selection criteria to a wide area survey has been capable of unveiling a population of X‐ray luminous, absorbed z > 1 quasars which is mostly missed in the traditional optical/X‐ray surveys performed so far. Advances in the understanding of the X‐ray properties of these recently‐discovered sources by Simbol‐X observations will be also discussed

    A Multimodal Sensory Apparatus for Robotic Prosthetic Feet Combining Optoelectronic Pressure Transducers and IMU

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    Timely and reliable identification of control phases is functional to the control of a powered robotic lower-limb prosthesis. This study presents a commercial energy-store-and-release foot prosthesis instrumented with a multimodal sensory system comprising optoelectronic pressure sensors (PS) and IMU. The performance was verified with eight healthy participants, comparing signals processed by two different algorithms, based on PS and IMU, respectively, for real-time detection of heel strike (HS) and toe-off (TO) events and an estimate of relevant biomechanical variables such as vertical ground reaction force (vGRF) and center of pressure along the sagittal axis (CoPy). The performance of both algorithms was benchmarked against a force platform and a marker-based stereophotogrammetric motion capture system. HS and TO were estimated with a time error lower than 0.100 s for both the algorithms, sufficient for the control of a lower-limb robotic prosthesis. Finally, the CoPy computed from the PS showed a Pearson correlation coefficient of 0.97 (0.02) with the same variable computed through the force platform

    Unveiling obscured accretion in the Chandra Deep Field South

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    A large population of heavily obscured, Compton Thick AGNs is predicted by models of galaxy formation, models of Cosmic X-ray Background and by the ``relic'' super-massive black-hole mass function measured from local bulges. However, so far only a handful of Compton thick AGNs have been possibly detected using even the deepest Chandra and XMM surveys. Compton-thick AGNs can be recovered thanks to the reprocessing of the AGN UV emission in the infrared by selecting sources with AGN luminosity's in the mid-infrared and faint near-infrared and optical emission. To this purpose, we make use of deep HST, VLT, Spitzer and Chandra data on the Chandra Deep Field South to constrain the number of Compton thick AGN in this field. We show that sources with high 24μ\mum to optical flux ratios and red colors form a distinct source population, and that their infrared luminosity is dominated by AGN emission. Analysis of the X-ray properties of these extreme sources shows that most of them (80±15\pm15%) are indeed likely to be highly obscured, Compton thick AGNs. The number of infrared selected, Compton thick AGNs with 5.8μ\mum luminosity higher than 1044.210^{44.2} erg s1^{-1} turns out to be similar to that of X-ray selected, unobscured and moderately obscured AGNs with 2-10 keV luminosity higher than 104310^{43} erg s1^{-1} in the redshift bin 1.2-2.6. This ``factor of 2'' source population is exactly what it is needed to solve the discrepancies between model predictions and X-ray AGN selection.Comment: Revised version, to be published by The Astrophysical Journa
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