18,475 research outputs found
Possibly New Charmed Baryon States from Decay
We examine the invariant mass spectrum of in decay measured by BABAR and find that through the 2-step processes of
, where denotes a
charmed baryon state, some of the peaks can be identified with the established
, and . Moreover, in
order to account for the measured spectrum, it is necessary to introduce a new
charmed baryon resonance with MeV.Comment: 8 pages, 1 figure, title changed and discussions updated, version
accepted for publication in Phys. Rev.
Tracking the Evolution of A Coherent Magnetic Flux Rope Continuously from the Inner to the Outer Corona
The magnetic flux rope (MFR) is believed to be the underlying magnetic
structure of coronal mass ejections (CMEs). However, it remains unclear how an
MFR evolves into and forms the multi-component structure of a CME. In this
paper, we perform a comprehensive study of an extreme-ultraviolet (EUV) MFR
eruption on 2013 May 22 by tracking its morphological evolution, studying its
kinematics, and quantifying its thermal property. As EUV brightenings begin,
the MFR starts to rise slowly and shows helical threads winding around an axis.
Meanwhile, cool filamentary materials descend spirally down to the
chromosphere. These features provide direct observational evidence of
intrinsically helical structure of the MFR. Through detailed kinematical
analysis, we find that the MFR evolution experiences two distinct phases: a
slow rise phase and an impulsive acceleration phase. We attribute the first
phase to the magnetic reconnection within the quasi-separatrix-layers
surrounding the MFR, and the much more energetic second phase to the fast
magnetic reconnection underneath the MFR. We suggest that the transition
between these two phases be caused by the torus instability. Moreover, we
identify that the MFR evolves smoothly into the outer corona and appears as a
coherent structure within the white light CME volume. The MFR in the outer
corona was enveloped by bright fronts that originated from plasma pile-up in
front of the expanding MFR. The fronts are also associated with the preceding
sheath region followed the outmost MFR-driven shock.Comment: 9 pages, 6 figures, and 1 table, accepted by ApJ; any comments are
welcome
Upper bounds on the first eigenvalue for a diffusion operator via Bakry-\'{E}mery Ricci curvature II
Let be a symmetric diffusion operator
with an invariant measure on a complete Riemannian
manifold. In this paper we prove Li-Yau gradient estimates for weighted
elliptic equations on the complete manifold with
and -dimensional Bakry-\'{E}mery Ricci curvature bounded below by some
negative constant. Based on this, we give an upper bound on the first
eigenvalue of the diffusion operator on this kind manifold, and thereby
generalize a Cheng's result on the Laplacian case (Math. Z., 143 (1975)
289-297).Comment: Final version. The original proof of Theorem 2.1 using Li-Yau
gradient estimate method has been moved to the appendix. The new proof is
simple and direc
Contextual cropping and scaling of TV productions
This is the author's accepted manuscript. The final publication is available at Springer via http://dx.doi.org/10.1007/s11042-011-0804-3. Copyright @ Springer Science+Business Media, LLC 2011.In this paper, an application is presented which automatically adapts SDTV (Standard Definition Television) sports productions to smaller displays through intelligent cropping and scaling. It crops regions of interest of sports productions based on a smart combination of production metadata and systematic video analysis methods. This approach allows a context-based composition of cropped images. It provides a differentiation between the original SD version of the production and the processed one adapted to the requirements for mobile TV. The system has been comprehensively evaluated by comparing the outcome of the proposed method with manually and statically cropped versions, as well as with non-cropped versions. Envisaged is the integration of the tool in post-production and live workflows
Wetting transitions of Ne
We report studies of the wetting behavior of Ne on very weakly attractive
surfaces, carried out with the Grand Canonical Monte Carlo method. The Ne-Ne
interaction was taken to be of Lennard-Jones form, while the Ne-surface
interaction was derived from an ab initio calculation of Chizmeshya et al.
Nonwetting behavior was found for Li, Rb, and Cs in the temperature regime
explored (i.e., T < 42 K). Drying behavior was manifested in a depleted fluid
density near the Cs surface. In contrast, for the case of Mg (a more attractive
potential) a prewetting transition was found near T= 28 K. This temperature was
found to shift slightly when a corrugated potential was used instead of a
uniform potential. The isotherm shape and the density profiles did not differ
qualitatively between these cases.Comment: 22 pages, 12 figures, submitted to Phys. Rev.
Towards End-to-end Video-based Eye-Tracking
Estimating eye-gaze from images alone is a challenging task, in large parts
due to un-observable person-specific factors. Achieving high accuracy typically
requires labeled data from test users which may not be attainable in real
applications. We observe that there exists a strong relationship between what
users are looking at and the appearance of the user's eyes. In response to this
understanding, we propose a novel dataset and accompanying method which aims to
explicitly learn these semantic and temporal relationships. Our video dataset
consists of time-synchronized screen recordings, user-facing camera views, and
eye gaze data, which allows for new benchmarks in temporal gaze tracking as
well as label-free refinement of gaze. Importantly, we demonstrate that the
fusion of information from visual stimuli as well as eye images can lead
towards achieving performance similar to literature-reported figures acquired
through supervised personalization. Our final method yields significant
performance improvements on our proposed EVE dataset, with up to a 28 percent
improvement in Point-of-Gaze estimates (resulting in 2.49 degrees in angular
error), paving the path towards high-accuracy screen-based eye tracking purely
from webcam sensors. The dataset and reference source code are available at
https://ait.ethz.ch/projects/2020/EVEComment: Accepted at ECCV 202
Plastic flow and failure resistance of metallic glass: Insight from \u3cem\u3ein situ\u3c/em\u3e compression of nanopillars
We report in situ nanocompression tests of Cu-Zr-Al metallic glass (MG) pillars in a transmission electron microscope. This technique is capable of spatially and temporally resolving the plastic flow in MGs. The observations reveal the intrinsic ability of fully glassy MGs to sustain large plastic strains, which would otherwise be preempted by catastrophic instability in macroscopic samples and conventional tests. The high ductility in volume-limited MGs and the sample size effects in suppressing the rapid failure common to MGs are analyzed by modeling the evolution of the collectivity of flow defects toward localization
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