12,529 research outputs found
Thermoelectric properties of (an-)isotropic QGP in magnetic fields
The Seebeck effect and the Nernst effect, reflecting the appearances of a
longitudinal electric field and a transverse electric field, and
, respectively, induced by a longitudinal thermal gradient, are studied
in QGP at a perpendicular magnetic field placed in -axis. We calculate the
associated Seebeck coefficient () and Nernst signal () using the
relativistic Boltzmann equation under the relaxation time approximation. In an
isotropic QGP, the influences of magnetic field () and quark chemical
potential () on these thermoelectric transport coefficients are
investigated. In the presence (absence) of weak magnetic field, we find
for a fixed is negative (positive) in sign, indicating that
the dominant carriers for converting heat gradient to electric field are
negatively (positively) charged quarks. The absolute value of
decreases with increasing temperature. Unlike , the sign of is
independent of charge carrier type, and its thermal behavior displays a peak
structure. In the presence of strong magnetic field, the motions of
(anti-)quarks perpendicular to magnetic field can be quantized, only the
Seebeck coefficient along the direction of magnetic field, , is
concentrated. Our results show that the value of at a fixed
in lowest Landau level (LLL) approximation always remains positive. Within the
effect of high Landau levels, exhibits a thermal structure similar to
that in LLL approximation. As Landau level increases further,
decreases and even its sign changes from positive to negative. The computation
of these thermoelectric transport coefficients are also extended to a medium
with momentum-anisotropy induced by initial spatial expansion as well as strong
magnetic field.Comment: 20 pages, 7 figure
5-(1H-Indol-3-ylmethylidene)-2,2-dimethyl-1,3-dioxane-4,6-dione
In the title compound, C15H13NO4, the conjugated double-bond system between the two rings adopts a cis configuration and there is an intramolecular indole–ketone C—H⋯O interaction. The indole N—H group forms an intermolecular hydrogen bond with a ketone O-atom acceptor, giving a chain structure along the ab direction. The O-heterocyclic ring adopts a boat conformation and makes a dihedral angle of 16.72 (6)° with the indole ring system
Consolidation effect of visual function training on children with different degrees of amblyopia
AIM: To observe the consolidation effect of visual function training in amblyopic therapy on children with amblyopia of different degrees(mild, moderate and severe)which had been normalized. <p>METHODS: Totally 78 amblyopic children were divided into two groups: visual function training group(<i>n</i>=36, 70 eyes)and control group(<i>n</i>=42, 67 eyes). The rollback situation of the two groups in 6, 12, 24 and 36 months were observed after visual acuity reached 0.9 during treatment.<p>RESULTS: The rollback rates were both 0 in visual function training group and control group with different degrees of amblyopia after 6 months. There was no significant difference in rollback rate between the 2 groups with different degrees of amblyopia after 6 and 12 months. There was no significant difference in rollback rate between the two groups with mild amblyopia after 24 and 36 months(<i>P</i>=0.269, 0.269). However, the rollback rate in training group with moderate amblyopia was significantly different from in control group after 24 and 36 months(<i>P</i>=0.004, 0.002). There was no significant difference in rollback rate between the two groups with severe amblyopia after 24 and 36 months. <p>CONCLUSION: Visual function training can reduce the rollback rate and consolidate the effect of amblyopic treatment effectively for children with moderate amblyopia. However, the effect is not as good for children with mild and severe amblyopia
Joint event extraction based on hierarchical event schemas from framenet
Event extraction is useful for many practical applications, such as news summarization and information retrieval. However, the popular automatic context extraction (ACE) event extraction program only defines very limited and coarse event schemas, which may not be suitable for practical applications. FrameNet is a linguistic corpus that defines complete semantic frames and frame-to-frame relations. As frames in FrameNet share highly similar structures with event schemas in ACE and many frames actually express events, we propose to redefine the event schemas based on FrameNet. Specifically, we extract frames expressing event information from FrameNet and leverage the frame-to-frame relations to build a hierarchy of event schemas that are more fine-grained and have much wider coverage than ACE. Based on the new event schemas, we propose a joint event extraction approach that leverages the hierarchical structure of event schemas and frame-to-frame relations in FrameNet. The extensive experiments have verified the advantages of our hierarchical event schemas and the effectiveness of our event extraction model. We further apply the results of our event extraction model on news summarization. The results show that the summarization approach based on our event extraction model achieves significant better performance than several state-of-the-art summarization approaches, which also demonstrates that the hierarchical event schemas and event extraction model are promising to be used in the practical applications
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