3,603 research outputs found
An Assembly Contamination Model
Mathematical model of spacecraft contamination for treating contamination amount and its surface distribution on structures as random variable
A preliminary quarantine analysis of a possible Mariner Venus 1972 mission
Spacecraft contamination preliminary quarantine analysis for possible 1972 Mariner Venus prob
Simultaneous Multi-Wavelength Observations of Magnetic Activity in Ultracool Dwarfs. I. The Complex Behavior of the M8.5 Dwarf TVLM513-46546
[Abridged] We present the first simultaneous radio, X-ray, ultraviolet, and
optical spectroscopic observations of the M8.5 dwarf TVLM513-46546, with a
duration of 9 hours. These observations are part of a program to study the
origin of magnetic activity in ultracool dwarfs, and its impact on
chromospheric and coronal emission. Here we detect steady quiescent radio
emission superposed with multiple short-duration, highly polarized flares;
there is no evidence for periodic bursts previously reported for this object,
indicating their transient nature. We also detect soft X-ray emission, with
L_X/L_bol~10^-4.9, the faintest to date for any object later than M5, and a
possible weak X-ray flare. TVLM513-46546 continues the trend of severe
violation of the radio/X-ray correlation in ultracool dwarfs, by nearly 4
orders of magnitude. From the optical spectroscopy we find that the Balmer line
luminosity exceeds the X-ray luminosity by a factor of a few, suggesting that,
unlike in early M dwarfs, chromospheric heating may not be due to coronal X-ray
emission. More importantly, we detect a sinusoidal H-alpha light curve with a
period of 2 hr, matching the rotation period of TVLM513-46546. This is the
first known example of such Balmer line behavior, which points to a co-rotating
chromospheric hot spot or an extended magnetic structure, with a covering
fraction of about 50%. This feature may be transitory based on the apparent
decline in light curve peak during the four observed maxima. From the radio
data we infer a large scale steady magnetic field of ~100 G, in good agreement
with the value required for confinement of the X-ray emitting plasma. The radio
flares, on the other hand, are produced in a component of the field with a
strength of ~3 kG and a likely multi-polar configuration.Comment: 13 pages, 4 figure
The Unidroit Draft Convention on the Hotelkeeper’s Contract: A Major Attempt to Unify the Law Governing Inkeeper-Guest Liability
Biofilm formation is a risk factor for mortality in patients with Candida albicans bloodstream infection-Scotland, 2012-2013
Acknowledgements This work was supported by the Wellcome Trust Strategic Award for Medical Mycology and Fungal Immunology 097377/Z/11/Z. Data collection was supported by a grant from Pfizer. G. Ramage was also supported by a research fellowship grant from Gilead Sciences. We are grateful to microbiology colleagues throughout Scotland for submitting isolates.Peer reviewedPublisher PD
Simultaneous Multi-Wavelength Observations of Magnetic Activity in Ultracool Dwarfs. II. Mixed Trends in VB10 and LSR1835+32 and the Possible Role of Rotation
[Abridged] As part of our on-going investigation of magnetic activity in
ultracool dwarfs we present simultaneous radio, X-ray, UV, and optical
observations of LSR1835+32 (M8.5), and simultaneous X-ray and UV observations
of VB10 (M8), both with a duration of about 9 hours. LSR1835+32 exhibits
persistent radio emission and H-alpha variability on timescales of ~0.5-2 hr.
The detected UV flux is consistent with photospheric emission, and no X-ray
emission is detected to a deep limit of L_X/L_bol<10^-5.7. The H-alpha and
radio emission are temporally uncorrelated, and the ratio of radio to X-ray
luminosity exceeds the correlation seen in F-M6 stars by >2x10^4. Similarly,
L_Halpha/L_X>10 is at least 30 times larger than in early M dwarfs, and
eliminates coronal emission as the source of chromospheric heating. The lack of
radio variability during four rotations of LSR1835+32 requires a uniform
stellar-scale field of ~10 G, and indicates that the H-alpha variability is
dominated by much smaller scales, <10% of the chromospheric volume. VB10, on
the other hand, shows correlated flaring and quiescent X-ray and UV emission,
similar to the behavior of early M dwarfs. Delayed and densely-sampled optical
spectra exhibit a similar range of variability amplitudes and timescales to
those seen in the X-rays and UV, with L_Halpha/L_X~1. Along with our previous
observations of the M8.5 dwarf TVLM513-46546 we conclude that late M dwarfs
exhibit a mix of activity patterns, which points to a transition in the
structure and heating of the outer atmosphere by large-scale magnetic fields.
We find that rotation may play a role in generating the fields as evidenced by
a tentative correlation between radio activity and rotation velocity. The X-ray
emission, however, shows evidence for super-saturation at vsini>25 km/s.Comment: Submitted to Ap
H0LiCOW III. Quantifying the effect of mass along the line of sight to the gravitational lens HE 0435-1223 through weighted galaxy counts
Based on spectroscopy and multiband wide-field observations of the
gravitationally lensed quasar HE 0435-1223, we determine the probability
distribution function of the external convergence for
this system. We measure the under/overdensity of the line of sight towards the
lens system and compare it to the average line of sight throughout the
universe, determined by using the CFHTLenS as a control field. Aiming to
constrain as tightly as possible, we determine
under/overdensities using various combinations of relevant informative weighing
schemes for the galaxy counts, such as projected distance to the lens,
redshift, and stellar mass. We then convert the measured under/overdensities
into a distribution, using ray-tracing through the
Millennium Simulation. We explore several limiting magnitudes and apertures,
and account for systematic and statistical uncertainties relevant to the
quality of the observational data, which we further test through simulations.
Our most robust estimate of has a median value
and a standard deviation of
. The measured corresponds to
uncertainty on the time delay distance, and hence the Hubble constant
inference from this system. The median value
is robust to (i.e. on ) regardless of the adopted
aperture radius, limiting magnitude and weighting scheme, as long as the latter
incorporates galaxy number counts, the projected distance to the main lens, and
a prior on the external shear obtained from mass modeling. The availability of
a well-constrained makes \hequad\ a valuable system for
measuring cosmological parameters using strong gravitational lens time delays.Comment: 24 pages, 17 figures, 6 tables. Submitted to MNRA
Personal, Social, and Environmental Mediators Associated With Increased Recreational Physical Activity in Women and Girls in the Kingdom of Tonga.
BACKGROUND: The purpose of this paper was to identify personal, social, and environmental mediators of recreational physical activity (PA) in a 6-month netball-based intervention for women and girls in Tonga. METHODS: Tonga Netball's "low-engagement village program" was implemented in 10 villages and aimed to increase the recreational PA levels in women and girls through a comprehensive, structured community-level netball program addressing key barriers to participation. In a mixed-methods approach, these mediating barriers were identified through qualitative interviews based on the socioecological model. Quantitative measures for mediators and recreational PA were then developed, and data from 301 women and girls were collected. Standard mediation analyses methods were then applied. RESULTS: Program participation appeared to significantly increase PA levels. Statistically significant personal mediators were body issues, preferring competitions, and clothing. Social mediators were support from sports council, community leaders, friends, and church. Environmental mediators were travel time and access to balls, bibs, and umpires. CONCLUSION: A comprehensive community-level program addressing key participation barriers can increase recreational PA among women and girls in Tonga. Triangulating these results with mediation analyses of variables on the causal pathway can strengthen our understanding of causation and inform funding prioritization for critical program components in similar contexts
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