1,930 research outputs found
Antecedents, Psychological Bonds to Multiple Targets and Outcomes: A qualitative Approach of their Links
Based on the re-conceptualization of the work commitment construct and on the notion of quondam commitment (Klein and al., 2012, 2014, 2017), this paper examines all the psychological bond types to multiple workplace targets, using a qualitative methodology approach. After providing a reminder of the theoretical background, the results of a case study, conducted in a major company, are presented. For that purpose, semi-structured interviews with 26 employees and the HR Manager were carried out and completed with a documentary analysis of the company’s website and corporate documents. A manual content analysis has been processed, using the NVivo software. The results show how complex and multifaceted the links between antecedents, psychological bonds towards different targets and their attitudinal/behavioural consequences are and provide a better understanding of the process model of commitment development or loss. Finally, we discuss key theoretical and managerial implications of our study
Studying the evolution of galaxies in compact groups over the past 3 Gyr - II. The importance of environment in the suppression of star formation
We present an in depth study on the evolution of galaxy properties in compact
groups over the past 3 Gyr. We are using the largest multi-wavelength sample
to-date, comprised 1770 groups (containing 7417 galaxies), in the redshift
range of 0.01<z<0.23. To derive the physical properties of the galaxies we rely
on ultraviolet (UV)-to-infrared spectral energy distribution modeling, using
CIGALE. Our results suggest that during the 3 Gyr period covered by our sample,
the star formation activity of galaxies in our groups has been substantially
reduced (3-10 times). Moreover, their star formation histories as well as their
UV-optical and mid-infrared colors are significantly different from those of
field and cluster galaxies, indicating that compact group galaxies spend more
time transitioning through the green valley. The morphological transformation
from late-type spirals into early-type galaxies occurs in the mid-infrared
transition zone rather than in the UV-optical green valley. We find evidence of
shocks in the emission line ratios and gas velocity dispersions of the
late-type galaxies located below the star forming main sequence. Our results
suggest that in addition to gas stripping, turbulence and shocks might play an
important role in suppressing the star formation in compact group galaxies.Comment: (Accepted for publication in MNRAS, date of submission November 18,
2015
Integration of landslide susceptibility maps for land use planning and civil protection emergency management
Landslides are one of the most relevant geomorphological hazards in Portugal, by the high levels of people affected, destruction of assets and disruption of economic and social activities. Regarding the Portuguese territorial land use planning and emergency management, regulation, practice, prevention and risk management have been promoted in different ways. In Portugal, the areas susceptible to landslides are included in the 'National Ecological Reserve', which is a public utility restriction legal figure that rules the land use planning at the municipal level. In addition, the Municipal Emergency Plans include landslide susceptibility maps that are combined with the map of the exposed elements, allowing the assessment of exposure to landslides. This study is applied to the Loures municipality located to the north of Lisbon. In this municipality 621 landslides registered in a landslide inventory (rotational slides, deep-seated translational slides and shallow translational slides) that affected 1,469,577 m2 (0.87 %) of the Loures territory. The final landslide susceptibility map shows that in Loures municipality 1,347 ha are associated to a Very high landslide susceptibility and 2,372 ha to High landslide susceptibility, which corresponds both to 22.1 % of the
entire municipality, and constitutes the larger fraction of the National Ecological Reserve, related to landslides. These areas do not present geomorphological and geotechnical suitability for building structures or infrastructures. From the civil protection and emergency management point of views 34 classes of exposed elements were identified in the municipality, with point, linear and polygonal representations. The elements at risk located in the Very High or High landslide susceptibility classes were summarized and correspond to: high voltage poles; wind turbines; transmission/reception antennas; industrial areas; water tanks; silo; gas station/tank; service area; buildings of educational institutions; worship buildings; buildings of electricity facilities; regular buildings; gas pipeline; motorways; national roads; and municipal roads.info:eu-repo/semantics/publishedVersio
Herschel Extreme Lensing Line Observations: Dynamics of two strongly lensed star forming galaxies near redshift z = 2
We report on two regularly rotating galaxies at redshift z=2, using high
resolution spectra of the bright [CII] 158 micron emission line from the HIFI
instrument on the Herschel Space Observatory. Both SDSS090122.37+181432.3
("S0901") and SDSS J120602.09+514229.5 ("the Clone") are strongly lensed and
show the double-horned line profile that is typical of rotating gas disks.
Using a parametric disk model to fit the emission line profiles, we find that
S0901 has a rotation speed v sin(i) = 120 +/- 7 km/s and gas velocity
dispersion sigma < 23 km/s. The best fitting model for the Clone is a
rotationally supported disk having v sin(i) = 79 +/- 11 km/s and sigma < 4km/s.
However the Clone is also consistent with a family of dispersion-dominated
models having sigma = 92 +/- 20 km/s. Our results showcase the potential of the
[CII] line as a kinematic probe of high redshift galaxy dynamics: [CII] is
bright; accessible to heterodyne receivers with exquisite velocity resolution;
and traces dense star-forming interstellar gas. Future [CII] line observations
with ALMA would offer the further advantage of spatial resolution, allowing a
clearer separation between rotation and velocity dispersion.Comment: 20 pages, 4 figures; in press at The Astrophysical Journa
Optical performance of the JWST MIRI flight model: characterization of the point spread function at high-resolution
The Mid Infra Red Instrument (MIRI) is one of the four instruments onboard
the James Webb Space Telescope (JWST), providing imaging, coronagraphy and
spectroscopy over the 5-28 microns band. To verify the optical performance of
the instrument, extensive tests were performed at CEA on the flight model (FM)
of the Mid-InfraRed IMager (MIRIM) at cryogenic temperatures and in the
infrared. This paper reports on the point spread function (PSF) measurements at
5.6 microns, the shortest operating wavelength for imaging. At 5.6 microns the
PSF is not Nyquist-sampled, so we use am original technique that combines a
microscanning measurement strategy with a deconvolution algorithm to obtain an
over-resolved MIRIM PSF. The microscanning consists in a sub-pixel scan of a
point source on the focal plane. A data inversion method is used to reconstruct
PSF images that are over-resolved by a factor of 7 compared to the native
resolution of MIRI. We show that the FWHM of the high-resolution PSFs were
5-10% wider than that obtained with Zemax simulations. The main cause was
identified as an out-of-specification tilt of the M4 mirror. After correction,
two additional test campaigns were carried out, and we show that the shape of
the PSF is conform to expectations. The FWHM of the PSFs are 0.18-0.20 arcsec,
in agreement with simulations. 56.1-59.2% of the total encircled energy
(normalized to a 5 arcsec radius) is contained within the first dark Airy ring,
over the whole field of view. At longer wavelengths (7.7-25.5 microns), this
percentage is 57-68%. MIRIM is thus compliant with the optical quality
requirements. This characterization of the MIRIM PSF, as well as the
deconvolution method presented here, are of particular importance, not only for
the verification of the optical quality and the MIRI calibration, but also for
scientific applications.Comment: 13 pages, submitted to SPIE Proceedings vol. 7731, Space Telescopes
and Instrumentation 2010: Optical, Infrared, and Millimeter Wav
The Antares Neutrino Telescope and Multi-Messenger Astronomy
Antares is currently the largest neutrino telescope operating in the Northern
Hemisphere, aiming at the detection of high-energy neutrinos from astrophysical
sources. Such observations would provide important clues about the processes at
work in those sources, and possibly help solve the puzzle of ultra-high energy
cosmic rays. In this context, Antares is developing several programs to improve
its capabilities of revealing possible spatial and/or temporal correlations of
neutrinos with other cosmic messengers: photons, cosmic rays and gravitational
waves. The neutrino telescope and its most recent results are presented,
together with these multi-messenger programs.Comment: 10 pages, 7 figures. Proceedings of the 14th Gravitational Wave Data
Analysis Workshop (GWDAW-14) in Roma - January 26th-29th, 201
Assessment of physical vulnerability of buildings and analysis of landslide risk at the municipal scale: application to the Loures municipality, Portugal
This study offers a semi-quantitative assessment
of the physical vulnerability of buildings to landslides in a
Portuguese municipality (Loures), as well as the quantitative
landslide risk analysis computed as the product of the
landslide hazard by the vulnerability and the economic value
of the buildings. The hazard was assessed by combining the
spatiotemporal probability and the frequency–magnitude relationship
of the landslides. The physical vulnerability assessment
was based on an inquiry of a pool of European landslide
experts and a sub-pool of landslide experts who know
the study area, and the answers’ variability was assessed with
standard deviation. The average vulnerability of the basic geographic
entities was compared by changing the map unit
and applying the vulnerability to all the buildings of a test
site, the inventory of which was listed on the field. The economic
value was calculated using an adaptation of the Portuguese
Tax Services approach, and the risk was computed
for different landslide magnitudes and different spatiotemporal
probabilities. As a rule, the vulnerability values given by
the sub-pool of experts who know the study area are higher
than those given by the European experts, namely for the
high-magnitude landslides. The obtained vulnerabilities vary
from 0.2 to 1 as a function of the structural building types and
the landslide magnitude, and are maximal for 10 and 20m
landslide depths. However, the highest risk was found for the
landslides that are 3m deep, because these landslides combine
a relatively high frequency in the Loures municipality
with a substantial potential damage.info:eu-repo/semantics/publishedVersio
Shock excitation of H in the James Webb Space Telescope era
(Abridged) H2 is the most abundant molecule in the Universe. Thanks to its
widely spaced energy levels, it predominantly lights up in warm gas, T > 100 K,
such as shocked regions, and it is one of the key targets of JWST observations.
These include shocks from protostellar outflows, all the way up to starburst
galaxies and AGN. Shock models are able to simulate H2 emission. We aim to
explore H2 excitation using such models, and to test over which parameter space
distinct signatures are produced in H2 emission. We present simulated H2
emission using the Paris-Durham shock code over an extensive grid of 14,000
plane-parallel stationary shock models, a large subset of which are exposed to
an external UV radiation field. The grid samples 6 input parameters: preshock
density, shock velocity, transverse magnetic field strength, UV radiation field
strength, cosmic-ray-ionization rate, and PAH abundance. Physical quantities,
such as temperature, density, and width, have been extracted along with H2
integrated line intensities. The strength of the transverse magnetic field, set
by the scaling factor, b, plays a key role in the excitation of H2. At low
values of b (<~ 0.3, J-type shocks), H2 excitation is dominated by
vibrationally excited lines; at higher values (b >~ 1, C-type shocks),
rotational lines dominate the spectrum for shocks with an external radiation
field comparable to (or lower than) the solar neighborhood. Shocks with b >= 1
can be spatially resolved with JWST for nearby objects. When the input kinetic
energy flux increases, the excitation and integrated intensity of H2 increases
similarly. An external UV field mainly serves to increase the excitation,
particularly for shocks where the input radiation energy is comparable to the
input kinetic energy flux. These results provide an overview of the energetic
reprocessing of input kinetic energy flux and the resulting H2 line emission.Comment: Published in A&
Turbulent molecular gas and star formation in the shocked intergalactic medium of Stephan's Quintet
We report on single-dish radio CO observations towards the inter-galactic
medium (IGM) of the Stephan's Quintet (SQ) group of galaxies. Extremely bright
mid-IR H2 rotational line emission from warm molecular gas has been detected by
Spitzer in the kpc-scale shock created by a galaxy collision. We detect in the
IGM CO(1-0), (2-1) and (3-2) line emission with complex profiles, spanning a
velocity range of 1000 km/s. The spectra exhibit the pre-shock recession
velocities of the two colliding gas systems (5700 and 6700 km/s), but also
intermediate velocities. This shows that much of the molecular gas has formed
out of diffuse gas accelerated by the galaxy-tidal arm collision. A total H2
mass of 5x10^9 Msun is detected in the shock. The molecular gas carries a large
fraction of the gas kinetic energy involved in the collision, meaning that this
energy has not been thermalized yet. The turbulent kinetic energy of the H2 gas
is at least a factor of 5 greater than the thermal energy of the hot plasma
heated by the collision. The ratio between the warm H2 mass derived from
Spitzer IRS spectroscopy and the H2 mass derived from CO fluxes is ~0.3 in the
IGM of SQ, which is 10-100 times higher than in star-forming galaxies. In the
shocked region, the ratio of the PAH-to-CO surface luminosities, commonly used
to measure the star formation efficiency of the H2 gas, is lower (up to a
factor 75) than the observed values in star-forming galaxies. We suggest that
turbulence fed by the galaxy-tidal arm collision maintains a high heating rate
within the H2 gas. This interpretation implies that the velocity dispersion on
the scale of giant molecular clouds in SQ is one order of magnitude larger than
the Galactic value. The high amplitude of turbulence may explain why this gas
is not forming stars efficiently. [abridged version]Comment: Revised abstract and small editing to match published version. 15
pages, 5 figures. Accepted for publication in Ap
- …