948 research outputs found
Impact of Bias Temperature Instability on Soft Error Susceptibility
In this paper, we address the issue of analyzing the effects of aging mechanisms on ICs' soft error (SE) susceptibility. In particular, we consider bias temperature instability (BTI), namely negative BTI in pMOS transistors and positive BTI in nMOS transistors that are recognized as the most critical aging mechanisms reducing the reliability of ICs. We show that BTI reduces significantly the critical charge of nodes of combinational circuits during their in-field operation, thus increasing the SE susceptibility of the whole IC. We then propose a time dependent model for SE susceptibility evaluation, enabling the use of adaptive SE hardening approaches, based on the ICs lifetime
High resolution forecast of heavy precipitation with Lokal Modell: analysis of two case studies in the Alpine area
Northern Italy is frequently affected by severe precipitation conditions often inducing flood events with associated loss of properties, damages and casualties. The capability of correctly forecast these events, strongly required for an efficient support to civil protection actions, is still nowadays a challenge. This difficulty is also related with the complex structure of the precipitation field in the Alpine area and, more generally, over the Italian territory. Recently a new generation of non-hydrostatic meteorological models, suitable to be used at very high spatial resolution, has been developed. <P style='line-height: 20px;'> In this paper the performance of the non-hydrostatic Lokal Modell developed by the COSMO Consortium, is analysed with regard to a couple of intense precipitation events occurred in the Piemonte region in Northern Italy. These events were selected among the reference cases of the Hydroptimet/INTERREG IIIB project. <P style='line-height: 20px;'> LM run at the operational resolution of 7km provides a good forecast of the general rain structure, with an unsatisfactory representation of the precipitation distribution across the mountain ranges. It is shown that the inclusion of the new prognostic equations for cloud ice, rain and snow produces a remarkable improvement, reducing the precipitation in the upwind side and extending the intense rainfall area to the downwind side. The unrealistic maxima are decreased towards observed values. The use of very high horizontal resolution (2.8 km) improves the general shape of the precipitation field in the flat area of the Piemonte region but, keeping active the moist convection scheme, sparse and more intense rainfall peaks are produced. When convective precipitation is not parametrised but explicitly represented by the model, this negative effect is removed
From blue star-forming to red passive: galaxies in transition in different environments
Exploiting a mass complete (M_*>10^(10.25)M_sun) sample at 0.03<z<0.11 drawn
from the Padova Millennium Galaxy Group Catalog (PM2GC), we use the (U-B)_rf
color and morphologies to characterize galaxies, in particular those that show
signs of an ongoing or recent transformation of their star formation activity
and/or morphology - green galaxies, red passive late types, and blue
star-forming early types. Color fractions depend on mass and only for
M_*<10^(10.7)M_sun on environment. The incidence of red galaxies increases with
increasing mass, and, for M_*<10^(10.7)M_sun, decreases toward the group
outskirts and in binary and single galaxies. The relative abundance of green
and blue galaxies is independent of environment, and increases monotonically
with galaxy mass. We also inspect galaxy structural parameters, star-formation
properties, histories and ages and propose an evolutionary scenario for the
different subpopulations. Color transformations are due to a reduction and
suppression of SFR in both bulges and disks which does not noticeably affect
galaxy structure. Morphological transitions are linked to an enhanced
bulge-to-disk ratio due to the removal of the disk, not to an increase of the
bulge. Our modeling suggests that green colors might be due to star formation
histories declining with long timescales, as an alternative scenario to the
classical "quenching" processes. Our results suggest that galaxy
transformations in star formation activity and morphology depend neither on
environment nor on being a satellite or the most massive galaxy of a halo. The
only environmental dependence we find is the higher fast quenching efficiency
in groups giving origin to post-starburst signatures.Comment: 20 pages, 12 figures, accepted for publication in Ap
The evolution of gender gaps in numeracy and literacy between childhood and young adulthood
Numeracy and literacy are important foundation skills which command significant wage premia in modern labour markets. The existence of gender differences in these skills is therefore of potential concern, and has spurred a large amount of research, especially with respect to numeracy skills. Still, little is known about the moment in which such gaps emerge, how they evolve, and if this evolution differs across countries. We use data from large scale international assessments to follow representative samples of birth-cohorts over time, and analyse how gender gaps in numeracy and literacy evolve from age 10 to age 27. We find that the advantage of boys in numeracy is small at age 10, but grows considerably between age 15 and 27. The gender gap in literacy follows a very different pattern: it is small at age 10, large and in favour of girls at age 15, and negligible by age 27
The star formation history of galaxies: the role of galaxy mass, morphology and environment
We analyze the star formation history (SFH) of galaxies as a function of
present-day environment, galaxy stellar mass and morphology. The SFH is derived
by means of a non-parametric spectrophotometric model applied to individual
galaxies at z ~ 0.04- 0.1 in the WINGS clusters and the PM2GC field. The field
reconstructed evolution of the star formation rate density (SFRD) follows the
values observed at each redshift (Madau & Dickinson 2014), except at z > 2
where our estimate is ~ 1.7x higher than the high-z observed value. The slope
of the SFRD decline with time gets progressively steeper going from low mass to
high mass haloes. The decrease of the SFRD since z = 2 is due to 1) quenching -
50% of the SFRD in the field and 75% in clusters at z > 2 originated in
galaxies that are passive today - and 2) the fact that the average SFR of
today's star-forming galaxies has decreased with time. We quantify the
contribution to the SFRD(z) of galaxies of today's different masses and
morphologies. The current morphology correlates with the current star formation
activity but is irrelevant for the past stellar history. The average SFH
depends on galaxy mass, but galaxies of a given mass have different histories
depending on their environment. We conclude that the variation of the SFRD(z)
with environment is not driven by different distributions of galaxy masses and
morphologies in clusters and field, and must be due to an accelerated formation
in high mass haloes compared to low mass ones even for galaxies that will end
up having the same galaxy mass today.Comment: 16 pages, 10 figures. Published on MNRA
Effect of kinetic resonances on the stability of Resistive Wall Mode in Reversed Field Pinch
The kinetic effects, due to the mode resonance with thermal particle drift
motions in the reversed field pinch (RFP) plasmas, are numerically investigated
for the stability of the resistive wall mode, using a non-perturbative
MHD-kinetic hybrid formulation. The kinetic effects are generally found too
weak to substantially change the mode growth rate, or the stability margin,
re-enforcing the fact that the ideal MHD model is rather adequate for
describing the RWM physics in RFP experiments.Comment: Submitted to: Plasma Phys. Control. Fusio
OmegaWINGS: OmegaCAM@VST observations of WINGS galaxy clusters
The Wide-field Nearby Galaxy-cluster Survey (WINGS) is a wide-field
multi-wavelength survey of X-ray selected clusters at z =0.04-0.07. The
original 34'x34' WINGS field-of- view has now been extended to cover a 1 sq.deg
field with both photometry and spectroscopy. In this paper we present the
Johnson B and V-band OmegaCAM/VST observations of 46 WINGS clusters, together
with the data reduction, data quality and Sextractor photometric catalogs.
With a median seeing of 1arcs in both bands, our 25-minutes exposures in each
band typically reach the 50% completeness level at V=23.1 mag. The quality of
the astrometric and photometric accuracy has been verified by comparison with
the 2MASS as well as with SDSS astrometry, and SDSS and previous WINGS imaging.
Star/galaxy separation and sky-subtraction procedure have been tested comparing
with previous WINGS data.
The Sextractor photometric catalogues are publicly available at the CDS, and
will be included in the next release of the WINGS database on the VO together
with the OmegaCAM reduced images. These data form the basis for a large ongoing
spectroscopic campaign with AAOmega/AAT and is being employed for a variety of
studies. [abridged]Comment: submitted to A&
Magnetic axis safety factor of finite β spheromaks and transition from spheromaks to toroidal magnetic bubbles
The value of the safety factor on the magnetic axis of a finite-beta spheromak is shown to be a function of beta in contrast to what was used in Bellan, Phys. Plasmas 9, 3050 (2002); this dependence on beta substantially reduces the gradient of the safety factor compared to the previous calculation. The method for generating finite-beta spheromak equilibria is extended to generate equilibria describing toroidal magnetic “bubbles,” where the hydrodynamic pressure on the magnetic axis is less than on the toroid surface. This “anti-confinement” configuration can be considered an equilibrium with an inverted beta profile and is relevant to interplanetary magnetic clouds as these clouds have lower hydrodynamic pressure in their interior than on their surface
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