230 research outputs found
Long-term polarization observations of Mira variable stars suggest asymmetric structures
Mira and semi-regular variable stars have been studied for centuries but
continue to be enigmatic. One unsolved mystery is the presence of polarization
from these stars. In particular, we present 40 years of polarization
measurements for the prototype o Ceti and V CVn and find very different
phenomena for each star. The polarization fraction and position angle for Mira
is found to be small and highly variable. On the other hand, the polarization
fraction for V CVn is large and variable, from 2 - 7 %, and its position angle
is approximately constant, suggesting a long-term asymmetric structure. We
suggest a number of potential scenarios to explain these observations.Comment: 2 pages, 1 figure, poster presented at IAU Symposium 301, Precision
Asteroseismology, August 2013, Wroclaw, Polan
Detecting foraminiferal photosymbionts in the fossil record: a combined micropalaeontological and geochemical approach
Poster from International Conference on Paleoceanography 12 (ICP 12). See the above link for more information on the conference
A Multi-Year Photopolarimetric Study of the Semi-Regular Variable V CVn and Identification of Analogue Sources
The semi-regular variable star V Canum Venaticorum (V CVn) is well-known for
its unusual linear polarization position angle (PA). Decades of observing V CVn
reveal a nearly constant PA spanning hundreds of pulsation cycles. This
phenomenon has persisted through variability that has ranged by 2 magnitudes in
optical brightness and through variability in the polarization amplitude over
0.3% and 6.9%. Additionally, the polarization fraction of V CVn varies
inversely with brightness.
This paper presents polarization measurements obtained over three pulsation
cycles. We find that the polarization maximum does not always occur precisely
at the same time as the brightness minimum. Instead, we observe a small lead or
lag in relation to the brightness minimum, spanning a period of a few days up
to three weeks. Furthermore, the PA sometimes exhibits a non-negligible
rotation, especially at lower polarization levels.
To elucidate the unusual optical behavior of V CVn, we present a list of
literature sources that also exhibit polarization variability with a roughly
fixed PA. We find this correlation occurs in stars with high tangential space
velocities, i.e., "runaway" stars, suggesting that the long-term constant PA is
related to how the circumstellar gas is shaped by the star's high-speed motion
through the interstellar medium.Comment: 9 pages + appendices, 7 figures, accepted for publication in A&
X-Ray Observations of the Peculiar Cepheid V473 Lyr Identify A Low-mass Companion
V473 Lyr is a classical Cepheid which is unique in having substantial
amplitude variations with a period of approximately 3.3 years, thought to be
similar to the Blazhko variations in RR Lyrae stars. We obtained an {\it
XMM-Newton} observation of this star to followup a previous detection in
X-rays. Rather than the X-ray burst and rapid decline near maximum radius seen
in Cephei itself, the X-ray flux in V473 Lyr remained constant for a
third of the pulsation cycle covered by the observation. Thus the X-rays are
most probably not produced by the changes around the pulsation cycle. The X-ray
spectrum is soft (kT = 0.6 keV), with
X-ray properties which are consistent with a young low mass companion.
Previously there was no evidence of a companion in radial velocities or in {\it
Gaia} and {\it Hipparcos} proper motions. While this rules out companions which
are very close or very distant, a binary companion at a separation between 30
and 300 AU is possible. This is an example of an X-ray observation revealing
evidence of a low mass companion, which is important in completing the mass
ratio statistics of binary Cepheids. Furthermore, the detection of a young
X-ray bright companion is a further indication that the Cepheid (primary) is a
Population I star, even though its pulsation behavior differs from other
classical Cepheids.Comment: Accepted by A
Associations of airway inflammation and responsiveness markers in non asthmatic subjects at start of apprenticeship
<p>Abstract</p> <p>Background</p> <p>Bronchial Hyperresponsiveness (BHR) is considered a hallmark of asthma. Other methods are helpful in epidemiological respiratory health studies including Fractional Exhaled Nitric Oxide (FENO) and Eosinophils Percentage (EP) in nasal lavage fluid measuring markers for airway inflammation along with the Forced Oscillatory Technique measuring Airway resistance (AR). Can their outcomes discriminate profiles of respiratory health in healthy subjects starting apprenticeship in occupations with a risk of asthma?</p> <p>Methods</p> <p>Rhinoconjunctivitis, asthma-like symptoms, FEV1 and AR post-Methacholine Bronchial Challenge (MBC) test results, FENO measurements and EP were all investigated in apprentice bakers, pastry-makers and hairdressers not suffering from asthma. Multiple Correspondence Analysis (MCA) was simultaneously conducted in relation to these groups and this generated a synthetic partition (EI). Associations between groups of subjects based on BHR and EI respectively, as well as risk factors, symptoms and investigations were also assessed.</p> <p>Results</p> <p>Among the 441 apprentice subjects, 45 (10%) declared rhinoconjunctivitis-like symptoms, 18 (4%) declared asthma-like symptoms and 26 (6%) suffered from BHR. The mean increase in AR post-MBC test was 21% (sd = 20.8%). The median of FENO values was 12.6 ppb (2.6-132 range). Twenty-six subjects (6.7%) had EP exceeding 14%. BHR was associated with atopy (p < 0.01) and highest FENO values (p = 0.09). EI identified 39 subjects with eosinophilic inflammation (highest values of FENO and eosinophils), which was associated with BHR and atopy.</p> <p>Conclusions</p> <p>Are any of the identified markers predictive of increased inflammatory responsiveness or of development of symptoms caused by occupational exposures? Analysis of population follow-up will attempt to answer this question.</p
Twinkle -- a small satellite spectroscopy mission for the next phase of exoplanet science
With a focus on off-the-shelf components, Twinkle is the first in a series of
cost competitive small satellites managed and financed by Blue Skies Space Ltd.
The satellite is based on a high-heritage Airbus platform that will carry a
0.45 m telescope and a spectrometer which will provide simultaneous wavelength
coverage from 0.5-4.5 . The spacecraft prime is Airbus Stevenage
while the telescope is being developed by Airbus Toulouse and the spectrometer
by ABB Canada. Scheduled to begin scientific operations in 2025, Twinkle will
sit in a thermally-stable, sun-synchronous, low-Earth orbit. The mission has a
designed operation lifetime of at least seven years and, during the first three
years of operation, will conduct two large-scale survey programmes: one focused
on Solar System objects and the other dedicated to extrasolar targets. Here we
present an overview of the architecture of the mission, refinements in the
design approach, and some of the key science themes of the extrasolar survey.Comment: Presented at SPIE Astronomical Telescopes & Instrumentation 202
Sense of coherence and diabetes: A prospective occupational cohort study
<p>Abstract</p> <p>Background</p> <p>Sense of coherence (SOC) is an individual characteristic related to a positive life orientation leading to effective coping. A weak SOC has been associated with indicators of general morbidity and mortality. However, the relationship between SOC and diabetes has not been studied in prospective design. The present study prospectively examined the relationship between a weak SOC and the incidence of diabetes.</p> <p>Methods</p> <p>The relationship between a weak SOC and the incidence of diabetes was investigated among 5827 Finnish male employees aged 18–65 at baseline (1986). SOC was measured by questionnaire survey at baseline. Data on prescription diabetes drugs from 1987 to 2004 were obtained from the Drug Imbursement Register held by the Social Insurance Institution.</p> <p>Results</p> <p>During the follow-up, 313 cases of diabetes were recorded. A weak SOC was associated with a 46% higher risk of diabetes in participants who had been =<50 years of age on entry into the study. This association was independent of age, education, marital status, psychological distress, self-rated health, smoking status, binge drinking and physical activity. No similar association was observed in older employees.</p> <p>Conclusion</p> <p>The results suggest that besides focusing on well-known risk factors for diabetes, strengthening SOC in employees of =<50 years of age can also play a role in attempts to tackle increasing rates of diabetes.</p
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