6,973 research outputs found
Lupus-TR-3b: A Low-Mass Transiting Hot Jupiter in the Galactic Plane?
We present a strong case for a transiting Hot Jupiter planet identified
during a single-field transit survey towards the Lupus Galactic plane. The
object, Lupus-TR-3b, transits a V=17.4 K1V host star every 3.91405d.
Spectroscopy and stellar colors indicate a host star with effective temperature
5000 +/- 150K, with a stellar mass and radius of 0.87 +/- 0.04M_sun and 0.82
+/- 0.05R_sun, respectively. Limb-darkened transit fitting yields a companion
radius of 0.89 +/- 0.07R_J and an orbital inclination of 88.3 +1.3/-0.8 deg.
Magellan 6.5m MIKE radial velocity measurements reveal a 2.4 sigma K=114 +/-
25m/s sinusoidal variation in phase with the transit ephemeris. The resulting
mass is 0.81 +/- 0.18M_J and density 1.4 +/- 0.4g/cm^3. Y-band PANIC image
deconvolution reveal a V>=21 red neighbor 0.4'' away which, although highly
unlikely, we cannot conclusively rule out as a blended binary with current
data. However, blend simulations show that only the most unusual binary system
can reproduce our observations. This object is very likely a planet, detected
from a highly efficient observational strategy. Lupus-TR-3b constitutes the
faintest ground-based detection to date, and one of the lowest mass Hot
Jupiters known.Comment: 4 pages, 4 figures, accepted for publication in ApJ
Morphological Classification of Galaxies by Shapelet Decomposition in the Sloan Digital Sky Survey II: Multiwavelength Classification
We describe the application of the `shapelet' linear decomposition of galaxy
images to multi-wavelength morphological classification using the
and -band images of 1519 galaxies from the Sloan Digital Sky Survey. We
utilize elliptical shapelets to remove to first-order the effect of inclination
on morphology. After decomposing the galaxies we perform a principal component
analysis on the shapelet coefficients to reduce the dimensionality of the
spectral morphological parameter space. We give a description of each of the
first ten principal component's contribution to a galaxy's spectral morphology.
We find that galaxies of different broad Hubble type separate cleanly in the
principal component space. We apply a mixture of Gaussians model to the
2-dimensional space spanned by the first two principal components and use the
results as a basis for classification. Using the mixture model, we separate
galaxies into three classes and give a description of each class's physical and
morphological properties. We find that the two dominant mixture model classes
correspond to early and late type galaxies, respectively. The third class has,
on average, a blue, extended core surrounded by a faint red halo, and typically
exhibits some asymmetry. We compare our method to a simple cut on color
and find the shapelet method to be superior in separating galaxies.
Furthermore, we find evidence that the decision boundary may not be
optimal for separation between early and late type galaxies, and suggest that
the optimal cut may be .Comment: 42 pages, 18 figs, revised version in press at AJ. Some modification
to the technique, more discussion, addition/deletion/modification of several
figures, color figures have been added. A high resolution version may be
obtained at
http://bllac.as.arizona.edu/~bkelly/shapelets/shapelets_ugriz.ps.g
Analyzing Feshbach resonances -- A Li -Cs case study
We provide a comprehensive comparison of a coupled channels calculation, the
asymptotic bound state model (ABM), and the multichannel quantum defect theory
(MQDT). Quantitative results for Li -Cs are presented and compared
to previously measured Li -Cs Feshbach resonances (FRs) [M. Repp et
al., Phys. Rev. A 87 010701(R) (2013)]. We demonstrate how the accuracy of the
ABM can be stepwise improved by including magnetic dipole-dipole interactions
and coupling to a non-dominant virtual state. We present a MQDT calculation,
where magnetic dipole-dipole and second order spin-orbit interactions are
included. A frame transformation formalism is introduced, which allows the
assignment of measured FRs with only three parameters. All three models achieve
a total rms error of < 1G on the observed FRs. We critically compare the
different models in view of the accuracy for the description of FRs and the
required input parameters for the calculations.Comment: 16 pages, 3 figures, 1 tabl
Setting a precautionary catch limit for Antarctic krill
A revised precautionary catch limit for Antarctic krill (Euphausia superba) in the Scotia Sea of 4 million tons was recently adopted by the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR). The limit was based on a total biomass of 44.3 million tons, as estimated from an acoustic and net survey of krill across the Scotia Sea sector of the Southern Ocean, and a harvest rate of 9.1%, as determined from an analysis of the risks of exceeding defined conservation criteria. We caution, however, that before the fishery can expand to the 4-inillion-ton level it will be necessary to establish mechanisms to avoid concentration of fishing effort, particularly in proximity to colonies of land-breeding krill predators, and to consider the effects of krill immigrating into the region from multiple sources
‘Perceptions of non-accidental child deaths as preventable events: The impact of probability heuristics and biases on child protection work'
Anxiety about the possibility of non-accidental deaths of children has had a major influence on child care policy and practice over the last 40 years. The formal inquiry reports and media coverage of these rare events serve to maintain the perception that these are regular incidents that happen far too often and that they could have been prevented. This focus on individual events tends to distort a clear view of the actual probability of non-accidental deaths and serves to reinforce the notion that potentially all child care cases are risky and that any social work practitioner could be involved in such a case. As a result, work with children has become highly risk averse. However, in statistical terms, the probability of non-accidental child deaths is very low and recently has averaged about 55 deaths a year. Children are at considerably higher risk of being killed on the roads.
This paper examines the way in which perceptions of the ‘high’ level of risk of possible child deaths are maintained despite the very low statistical probability of such incidents. It draws on thinking from behavioural psychology and, in particular the work of Kahneman and Tversky, to consider some of the biases in probability reasoning affecting people’s perception of risk and explores how inquiry reports into single past events reconfirm risk perceptions. It is suggested that recognition of the essentially unpredictable nature of future non-accidental child deaths would free up childcare professionals to work in a more positive and less risk-averse manner in the present
Power transformer dissolved gas analysis through Bayesian networks and hypothesis testing
Accurate diagnosis of power transformers is critical for the reliable and cost-effective operation of the power grid. Presently there are a range of methods and analytical models for transformer fault diagnosis based on dissolved gas analysis. However, these methods give conflicting results and they are not able to generate uncertainty information associated with the diagnostics outcome. In this situation it is not always clear which model is the most accurate. This paper presents a novel multiclass probabilistic diagnosis framework for dissolved gas analysis based on Bayesian networks and hypothesis testing. Bayesian network models embed expert knowledge, learn patterns from data and infer the uncertainty associated with the diagnostics outcome, and hypothesis testing aids in the data selection process. The effectiveness of the proposed framework is validated using the IEC TC 10 dataset and is shown to have a maximum diagnosis accuracy of 88.9%
Altered Resting-State Functional Connectivity of the Frontal-Striatal Reward System in Social Anxiety Disorder
We investigated differences in the intrinsic functional brain organization (functional connectivity) of the human reward system between healthy control participants and patients with social anxiety disorder. Functional connectivity was measured in the resting-state via functional magnetic resonance imaging (fMRI). 53 patients with social anxiety disorder and 33 healthy control participants underwent a 6-minute resting-state fMRI scan. Functional connectivity of the reward system was analyzed by calculating whole-brain temporal correlations with a bilateral nucleus accumbens seed and a ventromedial prefrontal cortex seed. Patients with social anxiety disorder, relative to the control group, had (1) decreased functional connectivity between the nucleus accumbens seed and other regions associated with reward, including ventromedial prefrontal cortex; (2) decreased functional connectivity between the ventromedial prefrontal cortex seed and lateral prefrontal regions, including the anterior and dorsolateral prefrontal cortices; and (3) increased functional connectivity between both the nucleus accumbens seed and the ventromedial prefrontal cortex seed with more posterior brain regions, including anterior cingulate cortex. Social anxiety disorder appears to be associated with widespread differences in the functional connectivity of the reward system, including markedly decreased functional connectivity between reward regions and between reward regions and lateral prefrontal cortices, and markedly increased functional connectivity between reward regions and posterior brain regions.Massachusetts Institute of Technology (Janet and Sheldon Razin Fellowship
Comparative evaluation of enteric bacterial culture and a molecular multiplex syndromic panel in children with acute gastroenteritis
Bogomol'nyi Limit For Magnetic Vortices In Rotating Superconductor
This work is the sequel of a previous investigation of stationary and
cylindrically symmetric vortex configurations for simple models representing an
incompressible non-relativistic superconductor in a rigidly rotating
background. In the present paper, we carry out our analysis with a generalized
Ginzburg-Landau description of the superconductor, which provides a
prescription for the radial profile of the normal density within the vortex.
Within this framework, it is shown that the Bogomol'nyi limit condition marking
the boundary between type I and type II behavior is unaffected by the rotation
of the background.Comment: 7 pages, uses RevTeX, submitted to Phys.Rev.
- …
