25,493 research outputs found
Vigorous atmospheric motion in the red supergiant star Antares
Red supergiant stars represent a late stage of the evolution of stars more
massive than about nine solar masses, in which they develop complex,
multi-component atmospheres. Bright spots have been detected in the atmosphere
of red supergiants using interferometric imaging. Above the photosphere of a
red supergiant, the molecular outer atmosphere extends up to about two stellar
radii. Furthermore, the hot chromosphere (5,000 to 8,000 kelvin) and cool gas
(less than 3,500 kelvin) of a red supergiant coexist at about three stellar
radii. The dynamics of such complex atmospheres has been probed by ultraviolet
and optical spectroscopy. The most direct approach, however, is to measure the
velocity of gas at each position over the image of stars as in observations of
the Sun. Here we report the mapping of the velocity field over the surface and
atmosphere of the nearby red supergiant Antares. The two-dimensional velocity
field map obtained from our near-infrared spectro-interferometric imaging
reveals vigorous upwelling and downdrafting motions of several huge gas clumps
at velocities ranging from about -20 to +20 kilometres per second in the
atmosphere, which extends out to about 1.7 stellar radii. Convection alone
cannot explain the observed turbulent motions and atmospheric extension,
suggesting that an unidentified process is operating in the extended
atmosphere.Comment: 27 pages, 8 figures, published in Natur
Interpersonal Emotion Regulation Questionnaire (IERQ): scale development and psychometric characteristics
Despite the popularity of emotion regulation in the contemporary literature, research has almost exclusively focused on only intrapersonal processes, whereas much less attention has been placed in interpersonal emotion regulation processes. In order to encourage research on interpersonal emotion regulation, we present a series of 4 studies to develop the Interpersonal Emotion Regulation Questionnaire (IERQ). The final scale consists of 20 items with 4 factors containing 5 items each. The 4 factors are: Enhancing Positive Affect; Perspective Taking; Soothing; and Social Modeling. The scale shows excellent psychometric characteristics. Implications for future research are discussed.R01 MH078308 - NIMH NIH HHS; R34 MH086668 - NIMH NIH HHS; R01 AT007257 - NCCIH NIH HHS; R21 MH101567 - NIMH NIH HHS; R34 MH099311 - NIMH NIH HHS; R21 MH102646 - NIMH NIH HHS; K23 MH100259 - NIMH NIH HHS; R01 MH099021 - NIMH NIH HH
Quantum walk versus classical wave: Distinguishing ground states of quantum magnets by spacetime dynamics
We investigate wave packet spreading after a single spin flip in prototypical two-dimensional ferromagnetic and antiferromagnetic quantum spin systems. We find characteristic spatial magnon density profiles: While the ferromagnet shows a square-shaped pattern reflecting the underlying lattice structure, as exhibited by quantum walkers, the antiferromagnet shows a circular-shaped pattern which hides the lattice structure and instead resembles a classical wave pattern. We trace these fundamentally different behaviors back to the distinctly different magnon energy-momentum dispersion relations and also provide a real-space interpretation. Our findings point to opportunities for real-time, real-space imaging of quantum magnets both in materials science and in quantum simulators
Entanglement and four wave mixing effects in the dissipation free nonlinear interaction of two photons at a single atom
We investigate the nonlinear interaction between two photons in a single
input pulse at an atomic two level nonlinearity. A one dimensional model for
the propagation of light to and from the atom is used to describe the precise
spatiotemporal coherence of the two photon state. It is shown that the
interaction generates spatiotemporal entanglement in the output state similar
to the entanglement observed in parametric downconversion. A method of
generating photon pairs from coherent pump light using this quantum mechanical
four wave mixing process is proposed.Comment: 10 pages, including 3 figures, correction in eq.(7), updated
references, final version for publication in PR
Learning Arbitrary Statistical Mixtures of Discrete Distributions
We study the problem of learning from unlabeled samples very general
statistical mixture models on large finite sets. Specifically, the model to be
learned, , is a probability distribution over probability
distributions , where each such is a probability distribution over . When we sample from , we do not observe
directly, but only indirectly and in very noisy fashion, by sampling from
repeatedly, independently times from the distribution . The problem is
to infer to high accuracy in transportation (earthmover) distance.
We give the first efficient algorithms for learning this mixture model
without making any restricting assumptions on the structure of the distribution
. We bound the quality of the solution as a function of the size of
the samples and the number of samples used. Our model and results have
applications to a variety of unsupervised learning scenarios, including
learning topic models and collaborative filtering.Comment: 23 pages. Preliminary version in the Proceeding of the 47th ACM
Symposium on the Theory of Computing (STOC15
Effect of treatments for depression on quality of life: a meta-analysis
Published in final edited form as: Cogn Behav Ther. 2017 June; 46(4): 265–286. doi:10.1080/16506073.2017.1304445.Cognitive-behavioral therapy (CBT) and selective serotonin reuptake inhibitors (SSRIs) are the two first-line treatments for depression, but little is known about their effects on quality of life (QOL). A meta-analysis was conducted to examine changes in QOL in adults with major depressive disorder who received CBT (24 studies examining 1969 patients) or SSRI treatment (13 studies examining 4286 patients) for their depression. Moderate improvements in QOL from pre to post-treatment were observed in both CBT (Hedges' g = .63) and SSRI (Hedges' g = .79) treatments. The effect size remained stable over the course of the follow-up period for CBT. No data were available to examine follow-ups in the SSRI group. QOL effect sizes decreased linearly with publication year, and greater improvements in depression were significantly associated with greater improvements in QOL for CBT, but not for SSRIs. CBT and SSRIs for depression were both associated with moderate improvements in QOL, but are possibly caused by different mechanisms.This work was supported in part from NIH/NCCIH [grant number R01AT007257], NIH/NIMH [grant numbers R01MH099021; R34MH099311; R34MH086668; R21MH102646; R21MH101567; K23MH100259]. (R01AT007257 - NIH/NCCIH; R01MH099021 - NIH/NIMH; R34MH099311 - NIH/NIMH; R34MH086668 - NIH/NIMH; R21MH102646 - NIH/NIMH; R21MH101567 - NIH/NIMH; K23MH100259 - NIH/NIMH
The intravenous glucose tolerance test and the behaviour of the free fatty acids in the detection of latent diabetes mellitus
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