1,999 research outputs found
Dynamic System Adaptation by Constraint Orchestration
For Paradigm models, evolution is just-in-time specified coordination
conducted by a special reusable component McPal. Evolution can be treated
consistently and on-the-fly through Paradigm's constraint orchestration, also
for originally unforeseen evolution. UML-like diagrams visually supplement such
migration, as is illustrated for the case of a critical section solution
evolving into a pipeline architecture.Comment: 19 page
Herschel imaging and spectroscopy of the nebula around the luminous blue variable star WRAY 15-751
We have obtained far-infrared Herschel PACS imaging and spectroscopic
observations of the nebular environment of the luminous blue variable WRAY
15-751. These images clearly show that the main, dusty nebula is a shell of
radius 0.5 pc and width 0.35 pc extending outside the H-alpha nebula. They also
reveal a second, bigger and fainter dust nebula, observed for the first time.
Both nebulae lie in an empty cavity, likely the remnant of the O-star wind
bubble formed when the star was on the main sequence. The kinematic ages of the
nebulae are about 20000 and 80000 years and each nebula contains about 0.05
Msun of dust. Modeling of the inner nebula indicates a Fe-rich dust. The
far-infrared spectrum of the main nebula revealed forbidden emission lines
coming from ionized and neutral gas. Our study shows that the main nebula
consists of a shell of ionized gas surrounded by a thin photodissociation
region illuminated by an "average" early-B star. The derived abundance ratios
N/O=1.0+/-0.4 and C/O=0.4+/-0.2 indicate a mild N/O enrichment. We estimate
that the inner shell contains 1.7+/-0.6 Msun of gas. Assuming a similar
dust-to-gas ratio for the outer nebula, the total mass ejected by WRAY 15-751
amounts to 4+/-2 Msun. The measured abundances, masses and kinematic ages of
the nebulae were used to constrain the evolution of the star and the epoch at
which the nebulae were ejected. Our results point to an ejection of the nebulae
during the RSG evolutionary phase of an ~ 40 Msun star. The presence of
multiple shells around the star suggests that the mass-loss was not a
continuous ejection but rather a series of episodes of extreme mass-loss. Our
measurements are compatible with the recent evolutionary tracks computed for an
40 Msun star with little rotation. They support the O-BSG-RSG-YSG-LBV filiation
and the idea that high-luminosity and low-luminosity LBVs follow different
evolutionary paths.Comment: 19 pages, 13 figures, accepted for publication in A&
Natural environments and suicide mortality in the Netherlands: a cross-sectional, ecological study
Background:
Natural outdoor environments, such as green spaces (ie, grass, forests, or parks), blue spaces (ie, visible bodies of fresh or salt water), and coastal proximity, have been increasingly shown to promote mental health. However, little is known about how and the extent to which these natural environments are associated with suicide mortality. Our aim was to investigate whether the availability of green space and blue space within people's living environments and living next to the coast are protective against suicide mortality.
Methods:
In this cross-sectional, ecological study, we analysed officially confirmed deaths by suicide between 2005 and 2014 per municipality in the Netherlands. We calculated indexes to measure the proportion of green space and blue space per municipality and the coastal proximity of each municipality using a geographical information system. We fitted Bayesian hierarchical Poisson regressions to assess associations between suicide risk, green space, blue space, and coastal proximity, adjusted for risk and protective factors.
Findings:
Municipalities with a large proportion of green space (relative risk 0·879, 95% credibility interval 0·779–0·991) or a moderate proportion of green space (0·919, 0·846–0·998) showed a reduced suicide risk compared with municipalities with less green space. Green space did not differ according to urbanicity in relation to suicide. Neither blue space nor coastal proximity was associated with suicide risk. The geographical variation in the residual relative suicide risk was substantial and the south of the Netherlands was at high risk.
Interpretation:
Our findings support the notion that exposure to natural environments, particularly to greenery, might have a role in reducing suicide mortality. If confirmed by future studies on an individual level, the consideration of environmental exposures might enrich suicide prevention programmes
PACS and SPIRE range spectroscopy of cool, evolved stars
Context: At the end of their lives AGB stars are prolific producers of dust
and gas. The details of this mass-loss process are still not understood very
well. Herschel PACS and SPIRE spectra offer a unique way of investigating
properties of AGB stars in general and the mass-loss process in particular.
Methods: The HIPE software with the latest calibration is used to process the
available PACS and SPIRE spectra of 40 evolved stars. The spectra are convolved
with the response curves of the PACS and SPIRE bolometers and compared to the
fluxes measured in imaging data of these sources. Custom software is used to
identify lines in the spectra, and to determine the central wavelengths and
line intensities. Standard molecular line databases are used to associate the
observed lines. Because of the limited spectral resolution of the spectrometers
several known lines are typically potential counterparts to any observed line.
To help identifications the relative contributions in line intensity of the
potential counterpart lines are listed for three characteristic temperatures
based on LTE calculations and assuming optically thin emission. Result: The
following data products are released: the reduced spectra, the lines that are
measured in the spectra with wavelength, intensity, potential identifications,
and the continuum spectra, i.e. the full spectra with all identified lines
removed. As simple examples of how this data can be used in future studies we
have fitted the continuum spectra with three power laws and find that the few
OH/IR stars seem to have significantly steeper slopes than the other oxygen-
and carbon-rich objects in the sample. As another example we constructed
rotational diagrams for CO and fitted a two-component model to derive
rotational temperatures.Comment: A&A accepte
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