576 research outputs found
The Collapse of the Wien Tail in the Coldest Brown Dwarf? Hubble Space Telescope Near-Infrared Photometry of WISE J085510.83-071442.5
We present Hubble Space Telescope (HST) near-infrared photometry of the
coldest known brown dwarf, WISE J085510.83071442.5 (WISE 08550714). WISE
08550714 was observed with the Wide Field Camera 3 (WFC3) aboard HST using
the F105W, F125W, and F160W filters, which approximate the , , and
near-infrared bands. WISE 08550714 is undetected at F105W with a
corresponding 2 magnitude limit of 26.9. We marginally detect
WISE 08550714 in the F125W images (S/N 4), with a measured magnitude
of 26.41 0.27, more than a magnitude fainter than the band magnitude
reported by Faherty and coworkers. WISE J08550714 is clearly detected in the
F160W band, with a magnitude of 23.90 0.02, the first secure detection of
WISE 08550714 in the near-infrared. Based on these data, we find that WISE
08550714 has extremely red F105WF125W and F125WF160W colors relative
to other known Y dwarfs. We find that when compared to the models of Saumon et
al. and Morley et al., the F105WF125W and F125WF160W colors of WISE
08550714 cannot be accounted for simultaneously. These colors likely
indicate that we are seeing the collapse of flux on the Wien tail for this
extremely cold object.Comment: Accepted for publication in ApJ Letter
Three New Cool Brown Dwarfs Discovered with the Wide-field Infrared Survey Explorer (WISE) and an Improved Spectrum of the Y0 Dwarf WISE J041022.71+150248.4
As part of a larger search of Wide-field Infrared Survey Explorer (WISE) data
for cool brown dwarfs with effective temperatures less than 1000 K, we present
the discovery of three new cool brown dwarfs with spectral types later than T7.
Using low-resolution, near-infrared spectra obtained with the NASA Infrared
Telescope Facility and the Hubble Space Telescope we derive spectral types of
T9.5 for WISE J094305.98+360723.5, T8 for WISE J200050.19+362950.1, and Y0: for
WISE J220905.73+271143.9. The identification of WISE J220905.73+271143.9 as a Y
dwarf brings the total number of spectroscopically confirmed Y dwarfs to
seventeen. In addition, we present an improved spectrum (i.e. higher
signal-to-noise ratio) of the Y0 dwarf WISE J041022.71+150248.4 that confirms
the Cushing et al. classification of Y0. Spectrophotometric distance estimates
place all three new brown dwarfs at distances less than 12 pc, with WISE
J200050.19+362950.1 lying at a distance of only 3.9-8.0 pc. Finally, we note
that brown dwarfs like WISE J200050.19+362950.1 that lie in or near the
Galactic plane offer an exciting opportunity to measure their mass via
astrometric microlensing.Comment: Accepted for publication in the Astronomical Journa
The 2MASS Wide-Field T Dwarf Search. II. Discovery of Three T Dwarfs in the Southern Hemisphere
We present the discovery of three new Southern Hemisphere T dwarfs identified
in the Two Micron All Sky Survey. These objects, 2MASS 0348-6022, 2MASS
0516-0445, and 2MASS 2228-4310, have classifications T7, T5.5, and T6.5,
respectively. Using linear absolute magnitude/spectral type relations derived
from T dwarfs with measured parallaxes, we estimate spectrophotometric
distances for these discoveries; the closest, 2MASS 0348-6022, is likely within
10 pc of the Sun. Proper motions and estimated tangential velocities are
consistent with membership in the Galactic disk population. We also list
Southern Hemisphere T dwarf candidates that were either not found in subsequent
near-infrared imaging observations and are most likely uncatalogued minor
planets, or have near-infrared spectra consistent with background stars.Comment: 12 pages including 4 figures (one as jpeg), accepted to A
Exploring the use of paragraph-level annotations for sentiment analysis of financial blogs
In this paper we describe our work in the area of topic-based sentiment analysis in the domain of financial blogs. We explore the use of paragraph-level and document-level annotations, examining how additional information from paragraph-level annotations can be used to increase the accuracy of document-level sentiment classification. We acknowledge the additional effort required to provide these paragraph-level annotations, and so we compare these findings against an automatic means of generating topic-specific sub-documents
Topic-dependent sentiment analysis of financial blogs
While most work in sentiment analysis in the financial domain has focused on the use of content from traditional finance news, in this work we concentrate on more subjective sources of information, blogs. We aim to automatically determine the sentiment of financial bloggers towards companies and their stocks. To do this we develop a corpus of financial blogs, annotated with polarity of sentiment with respect to a number of companies. We conduct an analysis of the annotated corpus, from which we show there is a significant level of topic shift within this collection, and also illustrate the difficulty that human annotators have when annotating certain sentiment categories. To deal with the problem of topic shift within blog articles, we propose text extraction techniques to create topic-specific sub-documents, which we use to train a sentiment classifier. We show that such approaches provide a substantial improvement over full documentclassification and that word-based approaches perform better than sentence-based or paragraph-based approaches
The effect of a national ambulance Quality Improvement Collaborative on performance in care bundles for acute myocardial infarction and stroke
Background: National ambulance service indicators showed considerable variation in care for acute myocardial infarction (AMI) and stroke. We aimed to improve reliability of pre-hospital care processes for these conditions using a Quality Improvement Collaborative (QIC). The QIC involved educating ambulance staff in Quality Improvement (QI) methods, and the use of plan-do-study-act cycles (PDSA) to implement changes. Ambulance staff were provided with feedback on the effect of the PDSA cycles and the QIC provided an environment to share successful strategies within and across services to improve care bundles for AMI and stroke.
Methods: We analysed change over time using logistic regression with three predictor variables: time (measured in weeks), sex, and age, to measure the effect of the national QIC on delivery of pre-hospital care bundles for AMI (aspirin, glyceryl trinitrate, pain assessment and analgesia) and stroke (face-arm-speech-test, blood pressure, blood glucose). The coefficient for time and its standard error were then extracted from each fit and plotted using forest plots.
Results: There were statistically significant improvements in nine (of 12) participating trusts for the AMI care bundle (OR 2.06, 95% CI 1.88 to 2.07) and nine (of 12) for the stroke care bundle (OR 2.84, 95% CI 2.45 to 3.30). Eleven of 12 trusts showed a significant improvement in either the AMI or stroke care bundle, and seven (of 12) showed significant improvements for both AMI and stroke. Overall performance for the care bundle for AMI increased nationally in England from 43 to 79 percent and for stroke from 83 to 96 percent.
Limitations: Our analysis was limited by lack of a comparison group.
Conclusion and recommendations: Implementing care bundles as part of a national QIC led to significant improvements care for AMI and stroke provided by English ambulance services. We are using a multisite comparative case study to explain why and how the QIC changed care
Rediscovery of the critically endangered ‘scarce yellow sally stonefly’ Isogenus nubecula in United Kingdom after a 22 year period of absence.
The critically endangered ‘scarce yellow sally stonefly’ Isogenus nubecula (Newman, 1833) (Plecoptera: Perlodidae) was rediscovered in the United Kingdom (UK) in 2017. This rediscovery comes after a 22-year period of absence despite numerous surveys since its last record in 1995. This species is one of the rarest stoneflies in the UK and Europe and its rediscovery is of international significance, being the westernmost point in Europe where the species is found, with the next nearest populations occurring in Austria and western Hungary, Slovakia, and central Sweden. The species is classed as pRDB2 (vulnerable), however is not listed in the British Red Data Book despite only being present (as far as records detail) in one river, the River Dee in North Wales, UK. Only fourteen individuals were caught and the need for conservation of this rare stonefly is therefore of paramount importance. We have made recommendations for the need to increase survey effort using environmental DNA (eDNA) techniques in order to fully understand the species range in this river and those in the surrounding area. The DNA sequence of I. nubecula has been uploaded on GenBank for further genetic studies. Captive rearing could also be explored with possible reintroductions to sites within its former UK range
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