49 research outputs found

    The evolution of the AGN content in groups up to z~1

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    Determining the AGN content in structures of different mass/velocity dispersion and comparing them to higher mass/lower redshift analogs is important to understand how the AGN formation process is related to environmental properties. We use our well-tested cluster finding algorithm to identify structures in the GOODS North and South fields, exploiting the available spectroscopic redshifts and accurate photometric redshifts. We identify 9 structures in GOODS-south (presented in a previous paper) and 8 new structures in GOODS-north. We only consider structures where at least 2/3 of the members brighter than M_R=-20 have a spectroscopic redshift. For those group members that coincide with X-ray sources in the 4 and 2 Msec Chandra source catalogs respectively, we determine if the X-ray emission originates from AGN activity or it is related to the galaxies' star-formation activity. We find that the fraction of AGN with Log L_H > 42 erg/s in galaxies with M_R < -20 is on average 6.3+-1.3%, much higher than in lower redshift groups of similar mass and more than double the fraction found in massive clusters at a similarly high redshift. We then explore the spatial distribution of AGN in the structures and find that they preferentially populate the outer regions. The colors of AGN host galaxies in structures tend to be confined to the green valley, thus avoiding the blue cloud and, partially, also the red-sequence, contrary to what happens in the field. We finally compare our results to the predictions of two sets of semi analytic models to investigate the evolution of AGN and evaluate potential triggering and fueling mechanisms. The outcome of this comparison attests the importance of galaxy encounters, not necessarily leading to mergers, as an efficient AGN triggering mechanism. (abridged)Comment: 11 pages, 8 figures, Accepted accepted for publication in A&

    A Photometrically Detected Forming Cluster of Galaxies at Redshift 1.6 in the GOODS Field

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    We report the discovery of a localized overdensity at z~1.6 in the GOODS-South Field, presumably a poor cluster in the process of formation. The three-dimensional galaxy density has been estimated on the basis of well calibrated photometric redshifts from the multiband photometric GOODS-MUSIC catalog using the (2+1)D technique. The density peak is embedded in the larger scale overdensity of galaxies known to exist at z=1.61 in the area. The properties of the member galaxies are compared to those of the surrounding field and we found that the two populations are significantly different supporting the reality of the structure. The reddest galaxies, once evolved according to their best fit models, have colors consistent with the red sequence of lower redshift clusters. The estimated M_200 total mass of the cluster is in the range 1.3 x 10^14 - 5.7x 10^14 Msun, depending on the assumed bias factor b. An upper limit for the 2-10 keV X-ray luminosity, based on the 1Ms Chandra observations, is L_X=0.5 x 10^43 erg s^-1, suggesting that the cluster has not yet reached the virial equilibrium.Comment: 6 pages, 5 figures (1 in color), uses emulateapj.cls Latex class file, accepted for publication in Ap

    New driver alterations in non-small cell lung cancer. A narrative review

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    Objective: This review aims to provide an up-to-date snapshot on the state of development of novel biomarker-driven treatments in non-small cell lung cancer (NSCLC). Background: The introduction of immune checkpoint inhibitors and target therapies has revolutionized the natural history of many NSCLCs, allowing for lasting and profound responses. In particular, mutations in the epidermal growth factor receptor (EGFR), rearrangements of the anaplastic lymphoma kinase (ALK), or oncogene c-Ros 1 (ROS1) have marked a paradigm shift in the treatment of NSCLC. Furthermore, new inhibitors for B-Raf proto-oncogene (BRAF), rearranged during transfection (RET), mesenchymal-to-epithelial transition factor (MET), or neurotrophic tyrosine kinase (NTRK) 1–3 have revealed fascinating data, obtaining accelerated approvals from the Food and Drug Administration (FDA) and European Medicines Agency (EMA). Today, the extensive use of next-generation sequencing (NGS) techniques has shown a broad molecular heterogeneity of NSCLC. Many of the mutations identified are considered potential therapeutic targets, and numerous studies are currently evaluating the efficacy of selective inhibitors. Methods: We carried out an extensive review of the literature on PubMed, Web of Science, and Scopus databases and the congress abstracts presented at the American Society of Clinical Oncology (ASCO), European Society for Medical Oncology (ESMO), and World Conference on Lung Cancer (WCLC) in the last 5 years. Our analysis considered works regarding new inhibitors for alterations of Kirsten rat sarcoma viral oncogene homolog (KRAS), PIK3CA, neuregulin-1 (NRG-1), human epidermal growth factor receptor 2 (HER2), fibroblast growth factor receptor (FGFR), genes that have recently become no longer undruggable. Conclusions: Precision oncology is revolutionizing the natural history of NSCLC. Several alterations have been identified as possible treatment targets, and numerous inhibitors show promising results in ongoing clinical trials

    The K20 survey. VI. The Distribution of the Stellar Masses in Galaxies up to z~2

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    We present a detailed analysis of the stellar mass content of galaxies up to z=2.5 in the K20 galaxy sample, that has a 92% spectroscopic completeness and a complete UBVRIzJKsUBVRIzJK_s multicolor coverage. We find that the M/L ratio decreases with redshift: in particular, the average M/L ratio of early type galaxies decreases with zz, with a scatter that is indicative of a range of star--formation time-scales and redshift of formation. More important, the typical M/L of massive early type galaxies is larger than that of less massive ones, suggesting that their stellar population formed at higher z. The final K20 galaxy sample spans a range of stellar masses from M*=10^9Msun to M*=10^12Msun, with massive galaxies ($M*>10^11Msun) detected up to z~2. We compute the Galaxy Stellar Mass Function at various z, of which we observe only a mild evolution (i.e. by 20-30%) up to z~1. At z>1, the evolution of the GSMF appears to be much faster: at z~2, about 35% of the present day stellar mass in objects with M*~10^11Msun appear to have assembled. We also detect a change in the physical nature of the most massive galaxies, since at z>1 a population of massive star--forming galaxies progressively appears. We finally analyze our results in the framework of Lambda-CDM hierarchical models. First, we show that the large number of massive galaxies detected at high z does not violate any fundamental Lambda-CDM constraint based on the number of massive DM halos. Then, we compare our results with the predictions of renditions of both semianalytic and hydro-dynamical models, that range from severe underestimates to slight overestimates of the observed mass density at z<~2. We discuss how the differences among these models are due to the different implementation of the main physical processes. (Abridged)Comment: Accepted for publication on Astronomy & Astrophysic

    The relative abundance of compact and normal massive early-type galaxies and its evolution from redshift z~2 to the present

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    We report on the evolution of the number density and size of early-type galaxies from z~2 to z~0. We select a sample of 563 massive (M>10^{10} Msun), passively evolving (SSFR<10^{-2} Gyr^{-1}) and morphologically spheroidal galaxies at 0<z<2.5, using the panchromatic photometry and spectroscopic redshifts available in the GOODS fields. We combine ACS and WFC3 HST images to study the morphology of our galaxies in their optical rest-frame in the whole 0<z<2.5 range. We find that throughout the explored redshift range the passive galaxies selected with our criteria have weak morphological K-correction, with size being slightly smaller in the optical than in the UV rest-frame (by ~20 and ~10 at z>1.2 and z<1.2, respectively). We measure a significant evolution of the mass-size relation of early-type galaxies, with the fractional increment that is almost independent on the stellar mass. Early-type galaxies (ETGs) formed at z>1 appear to be preferentially small, and the evolution of the mass-size relation at z<1 is driven by both the continuous size growth of the compact galaxies and the appearance of new ETGs with large sizes. We also find that the number density of all passive early-type galaxies increases rapidly, by a factor of 5, from z~2 to z~1, and then more mildly by another factor of 1.5 from z~1 to z~0. We interpret these results as the evidence that the bulk of the ETGs are formed at 1<z<3 through a mechanism that leaves very compact remnants. At z<1 the compact ETGs grow gradually in size, becoming normal size galaxies, and at the same time new ETGs with normal-large sizes are formed.Comment: accepted for publication in Ap

    Far-Ultraviolet and Far-Infrared Bivariate Luminosity Function of Galaxies: Complex Relation between Stellar and Dust Emission

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    Far-ultraviolet (FUV) and far-infrared (FIR) luminosity functions (LFs) of galaxies show a strong evolution from z=0z = 0 to z=1z = 1, but the FIR LF evolves much stronger than the FUV one. The FUV is dominantly radiated from newly formed short-lived OB stars, while the FIR is emitted by dust grains heated by the FUV radiation field. It is known that dust is always associated with star formation activity. Thus, both FUV and FIR are tightly related to the star formation in galaxies, but in a very complicated manner. In order to disentangle the relation between FUV and FIR emissions, we estimate the UV-IR bivariate LF (BLF) of galaxies with {\sl GALEX} and {\sl AKARI} All-Sky Survey datasets. Recently we invented a new mathematical method to construct the BLF with given marginals and prescribed correlation coefficient. This method makes use of a tool from mathematical statistics, so called "copula". The copula enables us to construct a bivariate distribution function from given marginal distributions with prescribed correlation and/or dependence structure. With this new formulation and FUV and FIR univariate LFs, we analyze various FUV and FIR data with {\sl GALEX}, {\sl Spitzer}, and {\sl AKARI} to estimate the UV-IR BLF. The obtained BLFs naturally explain the nonlinear complicated relation between FUV and FIR emission from star-forming galaxies. Though the faint-end of the BLF was not well constrained for high-zz samples, the estimated linear correlation coefficient ρ\rho was found to be very high, and is remarkably stable with redshifts (from 0.95 at z=0z = 0 to 0.85 at z=1.0z = 1.0). This implies the evolution of the UV-IR BLF is mainly due to the different evolution of the univariate LFs, and may not be controlled by the dependence structure.Comment: 10 pages, 7 figures, Earth, Planets and Space, in pres

    Multi-objective optimization using Deep Gaussian Processes: Application to Aerospace Vehicle Design

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    International audienceThis paper is focused on the problem of constrained multi-objective design optimization of aerospace vehicles. The design of such vehicles often involves disciplinary legacy models considered as black-box and computationally expensive simulations characterized by a possible non-stationary behavior (an abrupt change in the response or a different smoothness along the design space). The expensive cost of an exact function evaluation makes the use of classical evolutionary multi-objective algorithms not tractable. While Bayesian Optimization based on Gaussian Process regression can handle the expensive cost of the evaluations, the non-stationary behavior of the functions can make it inefficient. A recent approach consisting of coupling Bayesian Optimization with Deep Gaussian Processes showed promising results for single-objective non-stationary problems. This paper presents an extension of this approach to the multi-objective context. The efficiency of the proposed approach is assessed with respect to classical optimization methods on an analytical test-case and on an aerospace design problem

    L’indagine macrosismica: metodologia, parametri del terremoto, questioni aperte

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    Subito dopo l’evento del 6 aprile 2009, come di consueto Ăš stata realizzata una lunga e complessa indagine macrosismica, promossa dal gruppo operativo QUEST, che ha avuto inizialmente l’obiettivo di delimitare l’area di danneggiamento, a supporto delle attivitĂ  di pronto intervento della Protezione Civile, e successivamente quello di classificare nel modo piĂč accurato e capillare possibile, gli effetti prodotti dall’evento, particolarmente nelle aree danneggiate. A questo scopo Ăš stata prodotta una stima utilizzando la scala MCS (Sieberg, 1930); in un secondo momento Ăš stata rifinita l’indagine per una cinquantina di localitĂ  dell’area maggiormente danneggiata (Is MCS>VII), raccogliendo ed elaborando i dati in termini di scala macrosismica EMS98 (GrĂŒnthal, 1998). Per la complessitĂ  e la dimensione dei problemi affrontati, questo terremoto ha costituito un banco di prova di grande importanza per la macrosismologia italiana. In questo testo viene descritto il lavoro realizzato, discutendo in particolare alcuni aspetti che hanno messo alla prova le metodologie di indagine tradizionali (sistematiche irregolaritĂ  degli insediamenti monitorati, forti divergenze degli scenari di danno rispetto a quelli previsti dalle scale, difficile comparabilitĂ  con scenari storici, ecc.) e presentandone i risultati, in relazione ai parametri epicentrali che ne risultano e il loro contributo piĂč diretto alla comprensione complessiva della sismicitĂ  dell’area

    TOMO-ETNA experiment at Etna volcano: Activities on land

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    In the present paper we describe the on-land field operations integrated in the TOMO-ETNA experiment carried out in June-November 2014 at Mt. Etna volcano and surrounding areas. This terrestrial campaign consists in the deployment of 90 short-period portable three-component seismic stations, 17 broadband seismometers and the coordination with 133 permanent seismic station belonging to Italy’s Istituto Nazionale di Geofisica e Vulcanologia (INGV). This temporary seismic network recorded active and passive seismic sources. Active seismic sources were generated by an array of air-guns mounted in the Spanish oceanographic vessel “Sarmiento de Gamboa” with a power capacity of up to 5200 cubic inches. In total more than 26,000 shots were fired and more than 450 local and regional earthquakes were recorded. We describe the whole technical procedure followed to guarantee the success of this complex seismic experiment. We started with the description of the location of the potential safety places to deploy the portable network and the products derived from this search (a large document including full characterization of the sites, owners and indication of how to arrive to them). A full technical description of the seismometers and seismic sources is presented. We show how the portable seismic network was deployed, maintained and recovered in different stages. The large international collaboration of this experiment is reflected in the participation of more than 75 researchers, technicians and students from different institutions and countries in the on-land activities. The main objectives of the experiment were achieved with great success.PublishedS04272SR. VULCANI - Servizi e ricerca per la SocietàJCR Journalope
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