40,032 research outputs found
Plasma injection into a solar coronal loop
Context. The details of the spectral profiles of extreme UV emission lines
from solar active regions contain key information to investigate the structure,
dynamics, and energetics of the solar upper atmosphere. Aims. We characterize
the line profiles not only through the Doppler shift and intensity of the bulk
part of the profile. More importantly, we investigate the excess emission and
asymmetries in the line wings to study twisting motions and helicity. Methods.
WeusearasterscanoftheInterfaceRegionImagingSpectrograph(IRIS)inanactive region.
We concentrate on the Si iv line at 1394 {\AA} that forms just below 0.1 MK and
follow the plasma in a cool loop moving from one footpoint to the other. We
apply single-Gaussian fits to the line core, determine the excess emission in
the red and blue wings, and derive the red-blue line asymmetry. Results. The
blue wing excess at one footpoint shows injection of plasma into the loop that
is then flowing to the other side. At the same footpoint, redshifts of the line
core indicate that energy is deposited at around 0.1 MK. The enhanced pressure
would then push down the cool plasma and inject some plasma into the loop. In
the middle part of the loop, the spectral tilts of the line profiles indicate
the presence of a helical structure of the magnetic field, and the line wings
are symmetrically enhanced. This is an indication that the loop is driven
through the injection of helicity at the loop feet. Conclusions.
Iftheloopisdriventobehelical,thenonecanexpectthatthemagneticfieldwill be in a
turbulent state, as it has been shown by existing MHD models. The turbulent
motions could provide an explanation of the (symmetric) line wing enhancements
which have been seen also in loops at coronal temperatures, but have not been
understood so far.Comment: 26 pages, 11 figures, Accepted for publication in A&
Articulated Pose Estimation Using Hierarchical Exemplar-Based Models
Exemplar-based models have achieved great success on localizing the parts of
semi-rigid objects. However, their efficacy on highly articulated objects such
as humans is yet to be explored. Inspired by hierarchical object representation
and recent application of Deep Convolutional Neural Networks (DCNNs) on human
pose estimation, we propose a novel formulation that incorporates both
hierarchical exemplar-based models and DCNNs in the spatial terms.
Specifically, we obtain more expressive spatial models by assuming independence
between exemplars at different levels in the hierarchy; we also obtain stronger
spatial constraints by inferring the spatial relations between parts at the
same level. As our method strikes a good balance between expressiveness and
strength of spatial models, it is both effective and generalizable, achieving
state-of-the-art results on different benchmarks: Leeds Sports Dataset and
CUB-200-2011.Comment: 8 pages, 6 figure
Examining research productivity of Chinese TEFL academics across departments and institutes
This study aims to benchmark Chinese TEFL academics’ research productivities, as a way to identify and, subsequently, address research productivity issues. This study investigated 182 Chinese TEFL academics’ research outputs and perceptions about research across three Chinese higher education institutions using a literature-based survey. ANOVA, t-tests and descriptive statistics were used to analyse data from and between the three institutions. Findings indicated that more than 70% of the TEFL academics had produced no research in 10 of the 12 research output fields during 2004-2008. The English Language and Literature Department in the national university outperformed all other departments at the three institutes for most of the research output categories. While a majority of the participants seemed to hold positive perceptions about research, t-tests and ANOVA indicated that their research perceptions were significantly different across institutes and departments. Developing TEFL research capacity requires tertiary institutions to provide research-learning opportunities
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