70,558 research outputs found
Solar transition region in the quiet Sun and active regions
The solar transition region (TR), in which above the photosphere the tempera-
ture increases rapidly and the density drops dramatically, is believed to play
an important role in coronal heating and solar wind acceleration. Long-lasting
up-flows are present in the upper TR and interpreted as signatures of mass
supply to large coronal loops in the quiet Sun. Coronal bright points (BPs) are
local heating phenomena and we found a different Doppler-shift pattern at TR
and coronal temperatures in one BP, which might be related to the twisted loop
system. The dominant energy loss in the lower TR is the Ly-alpha emission. It
has been found that most Ly-alpha radiance profiles are stronger in the blue
peak, an asymmetry opposite to higher order Lyman lines. This asymmetry is
stronger when the downflow in the middle TR is stronger, indicating that the TR
flows play an important role in the line formation process. The peak separation
of Ly-alpha is found to be larger in coronal holes than in the quiet Sun,
reflecting the different magnetic structures and radiation fields between the
two regions. The Lyman line profiles are found to be not reversed in sunspot
plume and umbra regions, while they are obviously reversed in the surrounding
plage region. At TR temperatures, the densities of the sunspot plume and umbra
are a factor of 10 lower than of the plage, indicating that the sunspot plasma
emitting at TR temperatures is higher and possibly more extended above sunspots
than above the plage region.Comment: This paper has been withdrawn by the author because it's not a
referred pape
The Tensor Current Divergence Equation in U(1) Gauge Theories is Free of Anomalies
The possible anomaly of the tensor current divergence equation in U(1) gauge
theories is calculated by means of perturbative method. It is found that the
tensor current divergence equation is free of anomalies.Comment: Revtex4, 7 pages, 2 figure
Egocentric Hand Detection Via Dynamic Region Growing
Egocentric videos, which mainly record the activities carried out by the
users of the wearable cameras, have drawn much research attentions in recent
years. Due to its lengthy content, a large number of ego-related applications
have been developed to abstract the captured videos. As the users are
accustomed to interacting with the target objects using their own hands while
their hands usually appear within their visual fields during the interaction,
an egocentric hand detection step is involved in tasks like gesture
recognition, action recognition and social interaction understanding. In this
work, we propose a dynamic region growing approach for hand region detection in
egocentric videos, by jointly considering hand-related motion and egocentric
cues. We first determine seed regions that most likely belong to the hand, by
analyzing the motion patterns across successive frames. The hand regions can
then be located by extending from the seed regions, according to the scores
computed for the adjacent superpixels. These scores are derived from four
egocentric cues: contrast, location, position consistency and appearance
continuity. We discuss how to apply the proposed method in real-life scenarios,
where multiple hands irregularly appear and disappear from the videos.
Experimental results on public datasets show that the proposed method achieves
superior performance compared with the state-of-the-art methods, especially in
complicated scenarios
Observation of Landau level-like quantizations at 77 K along a strained-induced graphene ridge
Recent studies show that the electronic structures of graphene can be
modified by strain and it was predicted that strain in graphene can induce
peaks in the local density of states (LDOS) mimicking Landau levels (LLs)
generated in the presence of a large magnetic field. Here we report scanning
tunnelling spectroscopy (STS) observation of nine strain-induced peaks in LDOS
at 77 K along a graphene ridge created when the graphene layer was cleaved from
a sample of highly oriented pyrolytic graphite (HOPG). The energies of these
peaks follow the progression of LLs of massless 'Dirac fermions' (DFs) in a
magnetic field of 230 T. The results presented here suggest a possible route to
realize zero-field quantum Hall-like effects at 77 K
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