9,189 research outputs found
SPIDER X - Environmental effects in central and satellite early-type galaxies through the stellar fossil record
A detailed analysis of how environment affects the star formation history of
early-type galaxies (ETGs) is undertaken via high signal to noise ratio stacked
spectra obtained from a sample of 20,977 ETGs (morphologically selected) from
the SDSS-based SPIDER survey. Two major parameters are considered for the
study: the central velocity dispersion (sigma), which relates to local drivers
of star formation, and the mass of the host halo, which relates to
environment-related effects. In addition, we separate the sample between
centrals (the most massive galaxy in a halo) and satellites. We derive trends
of age, metallicity, and [alpha/Fe] enhancement, with sigma. We confirm that
the major driver of stellar population properties in ETGs is velocity
dispersion, with a second-order effect associated to the central/satellite
nature of the galaxy. No environmental dependence is detected for satellite
ETGs, except at low sigma - where satellites in groups or in the outskirts of
clusters tend to be younger than those in the central regions of clusters. In
contrast, the trends for centrals show a significant dependence on halo mass.
Central ETGs in groups (i.e. with a halo mass >10^12.5 M_Sun) have younger
ages, lower [alpha/Fe], and higher internal reddening, than "isolated" systems
(i.e. centrals residing in low-mass, <10^12.5 M_Sun, halos). Our findings imply
that central ETGs in groups formed their stellar component over longer time
scales than "isolated" centrals, mainly because of gas-rich interactions with
their companion galaxies.Comment: 22 pages, 19 figures, accepted for publication in MNRA
Influence of the hydrostatic and the deviatoric components of stress on ductility of metals
Failure of ductile metals occurring as microvoids growth is known to strongly depend on the stress triaxiality parameter which is a conventional measure of the first stress invariant normalized with respect to the equivalent von Mises stress, which in turn is a conventional measure of the second stress invariant. The triaxiality parameter is usually assumed to not influence the stress-strain behavior of metals according to the von Mises plasticity. The effects of the Lode angle and of the stress triaxiality are investigated here with regard to ductile failure and to
the stress-strain behavior. Experimental results and numerical predictions are compared for different metals and different specimen geometries, by investigating about
various failure criteria and a procedure for the
post-necking stress-strain characterization. Tensile specimens and notched plates are loaded up to failure, then finite elements simulations are verified by comparison with experimental data. The verified numerical data are then used to calculate local variables within the volume of
failing specimens; the knowledge of these local variables enables to predict global and local failure conditions according to the selected failure models
Electrical Characterization of a Thin Edgeless N-on-p Planar Pixel Sensors For ATLAS Upgrades
In view of the LHC upgrade phases towards the High Luminosity LHC (HL-LHC),
the ATLAS experiment plans to upgrade the Inner Detector with an all-silicon
system. Because of its radiation hardness and cost effectiveness, the n-on-p
silicon technology is a promising candidate for a large area pixel detector.
The paper reports on the joint development, by LPNHE and FBK of novel n-on-p
edgeless planar pixel sensors, making use of the active trench concept for the
reduction of the dead area at the periphery of the device. After discussing the
sensor technology, and presenting some sensors' simulation results, a complete
overview of the electrical characterization of the produced devices will be
given.Comment: 9 pages, 9 figures, to appear in the proceedings of the 15th
International Workshops on Radiation Imaging Detector
High resolution radio study of the Pulsar Wind Nebula within the Supernova Remnant G0.9+0.1
We have conducted a radio study at 3.6, 6 and 20 cm using ATCA and VLA and
reprocessed XMM-Newton and Chandra data of the pulsar wind nebula (PWN) in the
supernova remnant (SNR) G0.9+0.1. The new observations revealed that the
morphology and symmetry suggested by Chandra observations (torus and jet-like
features) are basically preserved in the radio range in spite of the rich
structure observed in the radio emission of this PWN, including several arcs,
bright knots, extensions and filaments. The reprocessed X-ray images show for
the first time that the X-ray plasma fills almost the same volume as the radio
PWN. Notably the X-ray maximum does not coincide with the radio maximum and the
neutron star candidate CXOU J174722.8-280915 lies within a small depression in
the radio emission. From the new radio data we have refined the flux density
estimates, obtaining S(PWN) ~ 1.57 Jy, almost constant between 3.6 and 20 cm.
For the whole SNR (compact core and shell), a flux density S(at 20 cm)= 11.5 Jy
was estimated. Based on the new and the existing 90 cm flux density estimates,
we derived alpha(PWN)=-0.18+/-0.04 and alpha(shell)=-0.68+/- 0.07. From the
combination of the radio data with X-ray data, a spectral break is found near
nu ~ 2.4 x 10^(12) Hz. The total radio PWN luminosity is L(radio)=1.2 x 10^(35)
erg s^(-1) when a distance of 8.5 kpc is adopted. By assuming equipartition
between particle and magnetic energies, we estimate a nebular magnetic field B
= 56 muG. The associated particle energy turns out to be U(part)=5 x 10^(47)
erg and the magnetic energy U(mag)=2 x 10^(47) erg. Based on an empirical
relation between X-ray luminosity and pulsar energy loss rate, and the
comparison with the calculated total energy, a lower limit of 1100 yr is
derived for the age of this PWN.Comment: 10 pages,8 figures, accepted for publication in A&A, June 13 200
Performance of Irradiated Thin Edgeless N-on-P Planar Pixel Sensors for ATLAS Upgrades
In view of the LHC upgrade phases towards the High Luminosity LHC (HL-LHC),
the ATLAS experiment plans to upgrade the Inner Detector with an all-silicon
system. Because of its radiation hardness and cost effectiveness, the n-on-p
silicon technology is a promising candidate for a large area pixel detector.
The paper reports on the joint development, by LPNHE and FBK of novel n-on-p
edgeless planar pixel sensors, making use of the active trench concept for the
reduction of the dead area at the periphery of the device. After discussing the
sensor technology, a complete overview of the electrical characterization of
several irradiated samples will be discussed. Some comments about detector
modules being assembled will be made and eventually some plans will be
outlined.Comment: 6 pages, 13 figures, to appear in the proceedings of the 2013 Nuclear
Science Symposium and Medical Imaging Conference. arXiv admin note: text
overlap with arXiv:1311.162
Wireless communication, identification and sensing technologies enabling integrated logistics: a study in the harbor environment
In the last decade, integrated logistics has become an important challenge in
the development of wireless communication, identification and sensing
technology, due to the growing complexity of logistics processes and the
increasing demand for adapting systems to new requirements. The advancement of
wireless technology provides a wide range of options for the maritime container
terminals. Electronic devices employed in container terminals reduce the manual
effort, facilitating timely information flow and enhancing control and quality
of service and decision made. In this paper, we examine the technology that can
be used to support integration in harbor's logistics. In the literature, most
systems have been developed to address specific needs of particular harbors,
but a systematic study is missing. The purpose is to provide an overview to the
reader about which technology of integrated logistics can be implemented and
what remains to be addressed in the future
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