714 research outputs found
Monitoring evolved stars for binarity with the HERMES spectrograph
Binarity is often invoked to explain peculiarities that can not be explained
by the standard theory of stellar evolution. Detecting orbital motion via the
Doppler effect is the best method to test binarity when direct imaging is not
possible. However, when the orbital period exceeds the duration of a typical
observing run, monitoring often becomes problematic. Placing a high-throughput
spectrograph on a small semi- robotic telescope allowed us to carry out a
radial-velocity survey of various types of peculiar evolved stars. In this
review we highlight some findings after the first four years of observations.
Thus, we detect eccentric binaries among hot subdwarfs, barium, S stars, and
post- AGB stars with disks, which are not predicted by the standard binary
interaction theory. In disk objects, in addition, we find signs of the on-
going mass transfer to the companion, and an intriguing line splitting, which
we attribute to the scattered light of the primary.Comment: To appear in the proceedings of the conference "Setting a new
standard in the analysis of binary stars", A. Tkachenko (ed.), European
Astron. Soc. Publ. Se
Divertor conditions relevant for fusion reactors achieved with linear plasma generator
Intense magnetized hydrogen and deuterium plasmas have been produced with electron densities up to 3.6¿×¿1020¿m-3 and electron temperatures up to 3.7¿eV with a linear plasma generator. Exposure of a W target has led to average heat and particle flux densities well in excess of 4¿MW m-2 and 1024¿m-2 s-1, respectively. We have shown that the plasma surface interactions are dominated by the incoming ions. The achieved conditions correspond very well to the projected conditions at the divertor strike zones of fusion reactors such as ITER. In addition, the machine has an unprecedented high gas efficiency
An index to quantify an individual's scientific research output that takes into account the effect of multiple coauthorship
I propose the index ("hbar"), defined as the number of papers of an
individual that have citation count larger than or equal to the of all
coauthors of each paper, as a useful index to characterize the scientific
output of a researcher that takes into account the effect of multiple
coauthorship. The bar is higher for .Comment: A few minor changes from v1. To be published in Scientometric
Is green space in the living environment associated with people's feelings of social safety?
Abstract.
The authors investigate whether the percentage of green space in people's living environ-
ment affects their feelings of social safety positively or negatively. More specifically they investigate
the extent to which this relationship varies between urban and rural areas, between groups in the
community that can be identified as more or less vulnerable, and the extent to which different types of
green space exert different influences. The study includes 83736 Dutch citizens who were interviewed
about their feelings of social safety. The percentage of green space in the living environment of each
respondent was calculated, and data analysed by use of a three-level latent variable model, controlled
for individual and environmental background characteristics. The analyses suggest that more green
space in people's living environment is associated with enhanced feelings of social safetyöexcept in
very strongly urban areas, where enclosed green spaces are associated with reduced feelings of social
safety. Contrary to the common image of green space as a dangerous hiding place for criminal activity
which causes feelings of insecurity, the results suggest that green space generally enhances feelings of
social safety. The results also suggest, however, that green space in the most urban areas is a matter
of concern with respect to social safety.
The power of interdependence: Linking health systems, communities, and health professions educational programs to better meet the needs of patients and populations
Promoting optimal health outcomes for diverse patients and populations requires the acknowledgement and strengthening of interdependent relationships between health professions education programs, health systems, and the communities they serve. Educational programs must recognize their role as integral components of a larger system. Educators must strive to break down silos and synergize efforts to foster a health care workforce positioned for collaborative, equitable, community-oriented practice. Sharing interprofessional and interinstitutional strategies can foster wide propagation of educational innovation while accommodating local contexts. This paper outlines how member schools of the American Medical Association Accelerating Change in Medical Education Consortium leveraged interdependence to accomplish transformative innovations catalyzed by systems thinking and a community of innovation
Divertor conditions relevant for fusion reactors achieved with linear plasma generator
The Spitzer Spectroscopic Survey of S-type Stars
S-type AGB stars are thought to be in the transitional phase between M-type
and C-type AGB stars. Because of their peculiar chemical composition, one may
expect a strong influence of the stellar C/O ratio on the molecular chemistry
and the mineralogy of the circumstellar dust. In this paper, we present a large
sample of 87 intrinsic galactic S-type AGB stars, observed at infrared
wavelengths with the Spitzer Space Telescope, and supplemented with
ground-based optical data. On the one hand, we derive the stellar parameters
from the optical spectroscopy and photometry, using a grid of model
atmospheres. On the other, we decompose the infrared spectra to quantify the
flux-contributions from the different dust species. Finally, we compare the
independently determined stellar parameters and dust properties. For the stars
without significant dust emission, we detect a strict relation between the
presence of SiS absorption in the Spitzer spectra and the C/O ratio of the
stellar atmosphere. These absorption bands can thus be used as an additional
diagnostic for the C/O ratio. For stars with significant dust emission, we
define three groups, based on the relative contribution of certain dust species
to the infrared flux. We find a strong link between group-membership and C/O
ratio. We show that these groups can be explained by assuming that the
dust-condensation can be cut short before silicates are produced, while the
remaining free atoms and molecules can then form the observed magnesium
sulfides or the carriers of the unidentified 13 and 20 micron features.
Finally, we present the detection of emission features attributed to molecules
and dust characteristic to C-type stars, such as molecular SiS, hydrocarbons
and magnesium sulfide grains. We show that we often detect magnesium sulfides
together with molecular SiS and we propose that it is formed by a reaction of
SiS molecules with Mg.Comment: Accepted for publication in A&
Manipulating the Optical Properties of Carbon Dots by Fine-Tuning their Structural Features
Contains fulltext :
207736.pdf (publisher's version ) (Closed access)11 p
LiMeS-Lab:An Integrated Laboratory for the Development of Liquid–Metal Shield Technologies for Fusion Reactors
The liquid metal shield laboratory (LiMeS-Lab) will provide the infrastructure to develop, test, and compare liquid metal divertor designs for future fusion reactors. The main research topics of LiMeS-lab will be liquid metal interactions with the substrate material of the divertor, the continuous circulation and capillary refilling of the liquid metal during intense plasma heat loading and the retention of plasma particles in the liquid metal. To facilitate the research, four new devices are in development at the Dutch Institute for Fundamental Energy Research and the Eindhoven University of Technology: LiMeS-AM: a custom metal 3D printer based on powder bed fusion; LiMeS-Wetting, a plasma device to study the wetting of liquid metals on various substrates with different surface treatments; LiMeS-PSI, a linear plasma generator specifically adapted to operate continuous liquid metal loops. Special diagnostic protection will also be implemented to perform measurements in long duration shots without being affected by the liquid metal vapor; LiMeS-TDS, a thermal desorption spectroscopy system to characterize deuterium retention in a metal vapor environment. Each of these devices has specific challenges due to the presence and deposition of metal vapors that need to be addressed in order to function. In this paper, an overview of LiMeS-Lab will be given and the conceptual designs of the last three devices will be presented.</p
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