1,530 research outputs found
A gas-rich AGN near the centre of a galaxy cluster at z ~ 1.4
The formation of the first virialized structures in overdensities dates back
to ~9 Gyr ago, i.e. in the redshift range z ~ 1.4 - 1.6. Some models of
structure formation predict that the star formation activity in clusters was
high at that epoch, implying large reservoirs of cold molecular gas. Aiming at
finding a trace of this expected high molecular gas content in primeval
clusters, we searched for the 12CO(2-1) line emission in the most luminous
active galactic nucleus (AGN) of the cluster around the radio galaxy 7C
1756+6520 at z ~ 1.4, one of the farthest spectroscopic confirmed clusters.
This AGN, called AGN.1317, is located in the neighbourhood of the central radio
galaxy at a projected distance of ~780 kpc. The IRAM Plateau de Bure
Interferometer was used to investigate the molecular gas quantity in AGN.1317,
observing the 12CO(2-1) emission line. We detect CO emission in an AGN
belonging to a galaxy cluster at z ~ 1.4. We measured a molecular gas mass of
1.1 x 10^10 Msun, comparable to that found in submillimeter galaxies. In
optical images, AGN.1317 does not seem to be part of a galaxy interaction or
merger.We also derived the nearly instantaneous star formation rate (SFR) from
Halpha flux obtaining a SFR ~65 Msun/yr. This suggests that AGN.1317 is
actively forming stars and will exhaust its reservoir of cold gas in ~0.2-1.0
Gyr.Comment: 5 pages, 3 figures, accepted for publication in Astronomy &
Astrophysic
Municipal solid waste prevention: A review of market-based instruments in six European Union countries
This article focuses on quantitative prevention of municipal solid waste among the 28 member countries of the European Union. A strict definition of waste prevention is used, including waste avoidance, waste reduction at source or in process, and product reuse, while recycling is outside the scope of this article. In order to provide a solid overview of the European situation, the study selected six countries (Belgium, Bulgaria, Italy, the Netherlands, Romania and Spain). Several selection requirements have been considered, such as geographic location or municipal solid waste per capita production trends from 1995 to 2017. A review of prevention programmes and other national strategic documents has been conducted. Extended producer responsibility, Pay-As-You-Throw schemes, Deposit-Refund Systems and Environmental Taxes implementation among the selected countries have been studied in order to understand how these market-based instruments can be used for the sake of waste prevention. Each market-based instrument has been further analysed using the Drivers Pressures State Impact Response model. Based on the results of this study, the effectiveness of market-based instruments implementation is strictly related to the context they are enforced in. It is particularly important to tailor the market-based instruments based on the implementation area. Nevertheless, market-based instruments, which are now mostly meant to boost the recycling sector of the considered Member States, should be designed to improve waste prevention performances, ensuring the achievement of the highest level of waste hierarchy promoted by the European Union
DESIGNING WITH EMOTIONAL AWARENESS
Abstract. The Italian school building heritage built between the seventies and eighties is every year increasingly abandoned and it remains in a state of neglect. It is increasingly necessary a recovery and enhancement methodology that preserves the memory of the place and at the same time, it makes it capable of adapting to the new needs of the city. The proposed research project originates from the study of the interactions between man and the environment applied to an architectural context with the identification of emotions. This methodology applied to citizenship, aims to make the population participate in the improvement from the point of view of well-being. This process was possible thanks to the combined use of immersive reality (VR) and the use of the GEW model, the data of which are the foundation and verification of the choices of architectural design, analyzed through the impacts on humans
Human-robot coexistence and interaction in open industrial cells
Recent research results on human\u2013robot interaction and collaborative robotics are leaving behind the traditional paradigm of robots living in a separated space inside safety cages, allowing humans and robot to work together for completing an increasing number of complex industrial tasks. In this context, safety of the human operator is a main concern. In this paper, we present a framework for ensuring human safety in a robotic cell that allows human\u2013robot coexistence and dependable interaction. The framework is based on a layered control architecture that exploits an effective algorithm for online monitoring of relative human\u2013robot distance using depth sensors. This method allows to modify in real time the robot behavior depending on the user position, without limiting the operative robot workspace in a too conservative way. In order to guarantee redundancy and diversity at the safety level, additional certified laser scanners monitor human\u2013robot proximity in the cell and safe communication protocols and logical units are used for the smooth integration with an industrial software for safe low-level robot control. The implemented concept includes a smart human-machine interface to support in-process collaborative activities and for a contactless interaction with gesture recognition of operator commands. Coexistence and interaction are illustrated and tested in an industrial cell, in which a robot moves a tool that measures the quality of a polished metallic part while the operator performs a close evaluation of the same workpiece
Earthquake Characteristics and Structural Properties of the Southern Tyrrhenian Basin from Full Seismic Wave Simulations
Modelling the response of seismic wavefields to sharp lateral variations in crustal discontinuities is essential for seismic tomography application and path effects correction in earthquake source characterization. This is particularly relevant when wavefields cross back-arc oceanic basins, i.e. mixed continental-oceanic settings. High-frequency (> 0.05 Hz) seismic waves resonate and get absorbed across these settings due to a shallow Moho, crustal heterogeneities, and energy leakage. Here, we provide the first high-frequency wave-equation model of full seismograms propagating through realistic 3D back-arc basins. Inversion by parameters trial based on correlation analyses identifies P-, S-and coda-wave as attributes able to estimate jointly 3D Moho variations, sediment thickness, and earthquake source characteristics using data from a single regional earthquake. We use as data waveforms produced by the Accumoli earthquake (Central Italy, 2016), propagating across the Southern Tyrrhenian basin and recorded across Southern Italy. The best model comprises a deep Moho ( similar to 18 km) in the middle of the basin and a crustal pinch with the continental crust in Sicily. The deep Moho corresponds to the Issel Bridge, a portion of continental crust trapped between the Vavilov and Marsili volcanic centres. The Accumoli earthquake is optimally described at a depth of 7.3 km using a boxcar with rise time of 6 s. Our results show that the early S-wave coda comprises trapped and reverberating phases sensitive to crustal interfaces. Forward modelling these waves is computationally expensive; however, adding these attributes to tomographic procedures allows modelling both source and structural parameters across oceanic basins
HII regions within a compact high velocity cloud. A nearly star-less dwarf galaxy?
Within the SECCO survey we identified a candidate stellar counterpart to the
Ultra Compact High Velocity Cloud (UCHVC) HVC274.68+74.70-123, that was
suggested by Adams et al. (2013) as a possible mini-halo within the Local Group
of galaxies. The spectroscopic follow-up of the brightest sources within the
candidate reveals the presence of two HII regions whose radial velocity is
compatible with physical association with the UVHVC. The available data does
not allow us to give a definite answer on the nature of the newly identified
system. A few alternative hypotheses are discussed. However, the most likely
possibility is that we have found a new faint dwarf galaxy residing in the
Virgo cluster of galaxies, which we name SECCO-1. Independently of its actual
distance, SECCO-1 displays a ratio of neutral hydrogen mass to V luminosity of
M_{HI}/L_V>= 20, by far the largest among local dwarfs. Hence, it appears as a
nearly star-less galaxy and it may be an example of the missing links between
normal dwarfs and the dark mini halos that are predicted to exist in large
numbers according to the currently accepted cosmological model.Comment: Accepted for publication in ApJ Letters. Pdflatex, emulateapj.cls. 6
pages, 3 figures, 2 table
Cool gas and dust in M33: Results from the Herschel M33 extended survey (HERM33ES)
We present an analysis of the first space-based far-IR-submm observations of
M 33, which measure the emission from the cool dust and resolve the giant
molecular cloud complexes. With roughly half-solar abundances, M33 is a first
step towards young low-metallicity galaxies where the submm may be able to
provide an alternative to CO mapping to measure their H content. In this
Letter, we measure the dust emission cross-section using SPIRE and
recent CO and \HI\ observations; a variation in is present from a
near-solar neighborhood cross-section to about half-solar with the maximum
being south of the nucleus. Calculating the total H column density from the
measured dust temperature and cross-section, and then subtracting the \HI\
column, yields a morphology similar to that observed in CO. The H/\HI\ mass
ratio decreases from about unity to well below 10% and is about 15% averaged
over the optical disk. The single most important observation to reduce the
potentially large systematic errors is to complete the CO mapping of M 33.Comment: 5 pages, 5 figures Accepted for publication in Astronomy and
Astrophysic
Gas accretion as the origin of chemical abundance gradients in distant galaxies
It has recently been suggested that galaxies in the early Universe can grow
through the accretion of cold gas, and that this may have been the main driver
of star formation and stellar mass growth. Because the cold gas is essentially
primordial, it has a very low abundance of elements heavier than helium
(metallicity). As it is funneled to the centre of a galaxy, it will lead the
central gas having an overall lower metallicity than gas further from the
centre, because the gas further out has been enriched by supernovae and stellar
winds, and not diluted by the primordial gas. Here we report chemical
abundances across three rotationally-supported star-forming galaxies at z~3,
only 2 Gyr after the Big Bang. We find an 'inverse' gradient, with the central,
star forming regions having a lower metallicity than less active ones, opposite
to what is seen in local galaxies. We conclude that the central gas has been
diluted by the accretion of primordial gas, as predicted by 'cold flow' models.Comment: To Appear in Nature Oct 14, 2010; Supplementary Information included
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Planetary nebulae in M33: probes of AGB nucleosynthesis and ISM abundances
We have obtained deep optical spectrophotometry of 16 planetary nebulae in
M33, mostly located in the central two kpc of the galaxy, with the Subaru and
Keck telescopes. We have derived electron temperatures and chemical abundances
from the detection of the [OIII]4363 line for the whole sample. We have found
one object with an extreme nitrogen abundance, 12+log(N/H)=9.20, accompanied by
a large helium content. After combining our data with those available in the
literature for PNe and HII regions, we have examined the behavior of nitrogen,
neon, oxygen and argon in relation to each other, and as a function of
galactocentric distance. We confirm the good correlation between Ne/H and O/H
for PNe in M33. Ar/H is also found to correlate with O/H. This strengthens the
idea that at the metallicity of the bright PNe analyzed in M33, which is
similar to that found in the LMC, these elements have not been significantly
modified during the dredge-up processes that take place during the AGB phase of
their progenitor stars. We find no significant oxygen abundance offset between
PNe and HII regions at any given galactocentric distance, despite the fact that
these objects represent different age groups in the evolution of the galaxy.
Combining the results from PNe and HII regions, we obtain a representative
slope of the ISM alpha-element (O, Ar, Ne) abundance gradient in M33 of -0.025
+/- 0.006 dex/kpc. Both PNe and HII regions display a large abundance
dispersion at any given distance from the galactic center. We find that the N/O
ratio in PNe is enhanced, relative to the HII regions, by approximately 0.8
dex.Comment: 21 pages, 20 figures. Accepted for publication in MNRA
Biological and molecular structure analyses of the controls on soil organic matter dynamics
Includes bibliographical references (page 170).The dynamics of soil organic carbon (SOC) are controlled by the interaction of biological, physical, and chemical parameters. These are best measured by a combination of techniques such as long-term field sites with a C3↔C4 plant switch. Acid hydrolysis and 14C- dating measure the mean residence time (MRT) of the resistant fraction. Long-term incubation allows the in situ biota to identify and decompose the labile SOC components. Statistical analysis (curve fitting) of the CO2 release curves, determines the pool size and of the two labile fractions (1). The effect of chemical structure is measured with pyrolysismolecular beam mass spectrometry (py-MBMS). The dynamics of charcoal, clay and silt are measured with both 13C and 14C
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