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Measuring the impact of observations on the predictability of the Kuroshio Extension in a shallow-water model
In this paper sequential importance sampling is used to assess the impact of observations on a ensemble prediction for the decadal path transitions of the Kuroshio Extension (KE). This particle filtering approach gives access to the probability density of the state vector, which allows us to determine the predictive power — an entropy based measure — of the ensemble prediction. The proposed set-up makes use of an ensemble that, at each time, samples the climatological probability distribution. Then, in a post-processing step, the impact of different sets of observations is measured by the increase in predictive power of the ensemble over the climatological signal during one-year. The method is applied in an identical-twin
experiment for the Kuroshio Extension using a reduced-gravity shallow water model. We investigate the impact of assimilating velocity observations from different locations during the elongated and the contracted meandering state of the KE. Optimal observations location correspond to regions with strong potential vorticity gradients. For the elongated state the optimal location is in the first meander of the KE. During the contracted state of the KE it is located south of Japan, where the Kuroshio separates from the coast
Entangled memories: how to study Europe’s cultural heritage
A fruitful direction for research on the European cultural heritage is to adopt a transnational approach. Rather than see cultural heritage as predominantly expressed in national contexts, it could be seen as primarily transnational and as plural. Such a view would also suggest a conception of national histories as themselves products of transnational encounters. In this perspective, the European dimension is not then necessarily something over and above nations, but part of their heritage. Moreover, as fundamentally transnational, the European heritage is not exclusively confined to Europe. Cultural heritage is not something that is fixed or based on an essence; it is produced and reinterpreted by social actors in different but overlapping contexts. This is also an interpretative approach that draws attention to the entangled nature of memories and especially the cultural logic by which new conceptions and narratives of heritage emerge from the encounter and entanglement of different memories. Such an approach offers new opportunities for comparative research on the European heritage as an entangled mosaic of histories and memories. This approach thus rejects not only particularistic but also universalistic ones such as alternative Eurocentric accounts
Resonance tuning and broadening of bowtie nanoantennas on graphene
Cataloged from PDF version of article.Metallic bowtie antennas are used in nanophotonics applications in order to confine the electromagnetic field into volumes much smaller than that of the incident wavelength. Electrically controllable carrier concentration of graphene opens the door to the use of plasmonic nanoantenna structures with graphene so that the resonant nature of nanoantennas can be tuned. In this study, we demonstrated with the Fourier transform infrared (FTIR) spectroscopy and the Finite Difference Time Domain (FDTD) method that the intensity and resonance peak of bowtie nanoantennas on monolayer graphene can be tuned at mid-infrared (MIR) wavelength regime by applying a gate voltage, since the optical properties of graphene change by changing the carrier concentration. (C) 2014 Elsevier B.V. All rights reserved
Dust Attenuation in Late-Type Galaxies. I. Effects on Bulge and Disk Components
We present results of new Monte Carlo calculations made with the DIRTY code
of radiative transfer of stellar and scattered radiation for a dusty giant
late-type galaxy like the Milky Way, which illustrate the effect of the
attenuation of stellar light by internal dust on the integrated photometry of
the individual bulge and disk components. Here we focus on the behavior of the
attenuation function, the color excess, and the fraction of light scattered or
directly transmitted towards the outside observer as a function of the total
amount of dust and the inclination of the galaxy, and the structure of the
dusty interstellar medium (ISM) of the disk. We confirm that dust attenuation
produces qualitatively and quantitatively different effects on the integrated
photometry of bulge and disk, whatever the wavelength. In addition, we find
that the structure of the dusty ISM affects more sensitively the observed
magnitudes than the observed colors of both bulge and disk. Finally, we show
that the contribution of the scattered radiation to the total monochromatic
light received by the outside observer is significant, particularly at UV
wavelengths, even for a two-phase, clumpy, dusty ISM. Thus understanding dust
scattering properties is fundamental for the interpretation of extragalactic
observations in the rest-frame UV.Comment: 62 pages, 28 eps-figures, 1 table, accepted for publication in ApJ
Main Journa
Brightest Cluster Galaxies and Core Gas Density in REXCESS Clusters
We investigate the relationship between brightest cluster galaxies (BCGs) and
their host clusters using a sample of nearby galaxy clusters from the
Representative XMM Cluster Structure Survey (REXCESS). The sample was imaged
with the Southern Observatory for Astrophysical Research (SOAR) in R band to
investigate the mass of the old stellar population. Using a metric radius of
12h^-1 kpc, we found that the BCG luminosity depends weakly on overall cluster
mass as L_BCG \propto M_cl^0.18+-0.07, consistent with previous work. We found
that 90% of the BCGs are located within 0.035 r_500 of the peak of the X-ray
emission, including all of the cool core (CC) clusters. We also found an
unexpected correlation between the BCG metric luminosity and the core gas
density for non-cool core (non-CC) clusters, following a power law of n_e
\propto L_BCG^2.7+-0.4 (where n_e is measured at 0.008 r_500). The correlation
is not easily explained by star formation (which is weak in non-CC clusters) or
overall cluster mass (which is not correlated with core gas density). The trend
persists even when the BCG is not located near the peak of the X-ray emission,
so proximity is not necessary. We suggest that, for non-CC clusters, this
correlation implies that the same process that sets the central entropy of the
cluster gas also determines the central stellar density of the BCG, and that
this underlying physical process is likely to be mergers.Comment: 16 pages, 8 figures, accepted Astrophysical Journa
Herschel observations of gamma-ray burst host galaxies: implications for the topology of the dusty interstellar medium
Long-duration gamma-ray bursts (GRBs) are indisputably related to star
formation, and their vast luminosity in gamma rays pin-points regions of star
formation independent of galaxy mass. As such, GRBs provide a unique tool for
studying star forming galaxies out to high-z independent of luminosity. Most of
our understanding of the properties of GRB hosts (GRBHs) comes from optical and
near-infrared (NIR) follow-up observations, and we therefore have relatively
little knowledge of the fraction of dust-enshrouded star formation that resides
within GRBHs. Currently ~20% of GRBs show evidence of significant amounts of
dust along the line of sight to the afterglow through the host galaxy, and
these GRBs tend to reside within redder and more massive galaxies than GRBs
with optically bright afterglows. In this paper we present Herschel
observations of five GRBHs with evidence of being dust-rich, targeted to
understand the dust attenuation properties within GRBs better. Despite the
sensitivity of our Herschel observations, only one galaxy in our sample was
detected (GRBH 070306), for which we measure a total star formation rate (SFR)
of ~100Mstar/yr, and which had a relatively high stellar mass
(log[Mstar]=10.34+0.09/-0.04). Nevertheless, when considering a larger sample
of GRBHs observed with Herschel, it is clear that stellar mass is not the only
factor contributing to a Herschel detection, and significant dust extinction
along the GRB sightline (A_{V,GRB}>1.5~mag) appears to be a considerably better
tracer of GRBHs with high dust mass. This suggests that the extinguishing dust
along the GRB line of sight lies predominantly within the host galaxy ISM, and
thus those GRBs with A_{V,GRB}>1~mag but with no host galaxy Herschel
detections are likely to have been predominantly extinguished by dust within an
intervening dense cloud.Comment: 14 pages, 7 figures. Accepted for publication in A&
Environmental assessment of light weighting solutions for automotive components: results, trade‐off and challenges from real case studies
In the last few decades, the automotive industry is facing the most deal with sustainability programs due to the increase of legislate limits on CO2 emissions and vehicle recyclability rate. Consequently, decisions on products design and development go together with environmental considerations, by starting to look for the employment of lighter materials, thus reducing vehicle mass weight and therefore fuel consumption and CO2 emissions during the dominant operation stage of a vehicle’s life cycle. To tackle this problem many of today automotive components are made of alternative materials like plastics, polymer composites, lighter metals which should lead to weight reduction with the same mechanical performances. Magneti Marelli® designs and produces hi-tech systems and components for the automotive sector representing a significant contribution on vehicle mass weight with a roughly 15% portion of incidence. So, in accordance to the environmental regulations, the Company has started to get involved into sustainability programs by focusing attention on the environmental impact of its products. In particular since 2012 Magneti Marelli has included in its mission the “improvement of environmental and energy performances of products and relatives processes during their whole life cycle, through innovative methodologies that assess the potential impacts in a quantitative way”, in this way highlighting the importance of meeting the increasing stakeholders’ expectations and their requests for transparency in results’ communication.
This work addresses the main outcomes stemmed from the several LCA studies carried out over different components in terms of materials and technologies production allowing a wider environmental conscious related to the usage of different materials and manufacturing processes.
Results showed that the materials employed offer the major contribution on the total impact especially for raw materials extraction and production and for the vehicle use phase, with a further substantial difference connected to the use of virgin instead of recycled materials.
The main discussed points will be: i) the trade-off between production phase and use phase impacts; ii) End-of-Life analysis at component level beside the ISO 22628:2002 for the whole vehicle; iii) critical analysis and selection of environmental indicators significant for the automotive sector.
Keywords Automotive sector, Life Cycle Assessment, vehicle component, Sustainable Manufacturing, Design for Environment, composites, light weightin
Near-infrared observations of galaxies in Pisces-Perseus: I. H-band surface photometry of 174 spirals
We present near-infrared, H-band (1.65 um), surface photometry of 174 spiral
galaxies in the area of the Pisces-Perseus supercluster. The images, acquired
with the ARNICA camera mounted on various telescopes, are used to derive radial
profiles of surface brightness, ellipticities, and position angles, together
with global parameters such as H-band magnitudes and diameters. The mean
relation between H-band isophotal diameter D_{21.5} and the B-band D_{25}
implies a B-H color of the outer disk bluer than 3.5; moreover, D_{21.5}/D_{25}
depends on (global) color and absolute luminosity. The correlations among the
various photometric parameters suggest a ratio between isophotal radius
D_{21.5}/2 and disk scale length of about 3.5 and a mean disk central
brightness of 17.5 H-mag arcsec^{-2}. We confirm the trend of the concentration
index C_{31} with absolute luminosity and, to a lesser degree, with
morphological type. We also assess the influence of non-axisymmetric structures
on the radial profiles and on the derived parameters.Comment: 10 pages, 11 postscript figures (one table and one figure are
available only at the CDS); to be published on A&A
Near-Infrared Adaptive Optics Imaging of the Central Regions of Nearby Sc Galaxies. II. NGC 247 and NGC 2403
J, H, and K' images obtained with the Canada-France-Hawaii Telescope adaptive
optics system are used to investigate the star-forming histories of the central
regions of the Sc galaxies NGC 247 and NGC 2403. The brightest resolved red
stars within 15 arcsec of the nucleus of each galaxy are red supergiants,
indicating that the central few hundred parsecs of these galaxies experienced
star formation within the last ~ 0.1 Gyr. However, when averaged over Gyr time
scales, the star-forming histories of the inner disks of these galaxies have
been remarkably similar, as expected if the long-term evolution of disks is
defined by local characteristics such as mass density. It is demonstrated that
NGC 247 and NGC 2403, like M33, harbour nuclear star clusters with stellar
contents that differ from the surrounding central light concentrations. The
nucleus of NGC 2403 is significantly bluer than that of the other two galaxies
and the K-band surface brightnesses near the centers of NGC 247 and NGC 2403
are 1 -- 2 mag per square arcsec lower than in M33. Finally, it is noted that
young or intermediate-age nuclear star clusters are a common occurence in
nearby spirals, indicating that nuclear star formation in these objects is
either continuous or episodic on time scales of 0.1 - 1 Gyr.Comment: 27 pages of text and 14 figures; to appear in the Astronomical
Journa
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