49 research outputs found
The evolution of the AGN content in groups up to z~1
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
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
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) 1â3 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
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 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 , 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
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
Far-ultraviolet (FUV) and far-infrared (FIR) luminosity functions (LFs) of
galaxies show a strong evolution from to , 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- samples, the estimated linear
correlation coefficient was found to be very high, and is remarkably
stable with redshifts (from 0.95 at to 0.85 at ). 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
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
Lâindagine macrosismica: metodologia, parametri del terremoto, questioni aperte
Subito dopo lâevento 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 lâobiettivo di delimitare lâarea 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 dallâevento, 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 lâindagine per una cinquantina di localitĂ dellâarea 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 dellâarea
TOMO-ETNA experiment at Etna volcano: Activities on land
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 Italyâs 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
âSarmiento de Gamboaâ 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 SocietĂ JCR Journalope