33,191 research outputs found
Fermi surface evolution in the antiferromagnetic state for the electron-doped t-t'-t''-J model
By use of the slave-boson mean-field approach, we have studied the
electron-doped t-t'-t''-J model in the antiferromagnetic (AF) state. It is
found that at low doping the Fermi surface (FS) pockets appear around
and , and upon increasing doping the other ones will
form around . The evolution of the FS with
doping as well as the calculated spectral weight are consistent with the
experimental results.Comment: Fig. 4 is updated, to appear in Phys. Rev.
Antiarrhythmic and proarrhythmic effects of subcutaneous nerve stimulation in ambulatory dogs
Background
High output subcutaneous nerve stimulation (ScNS) remodels the stellate ganglia and suppresses cardiac arrhythmia.
Objective
To test the hypothesis that long duration low output ScNS causes cardiac nerve sprouting, increases plasma norepinephrine concentration and the durations of paroxysmal atrial tachycardia (PAT) in ambulatory dogs.
Methods
We prospectively randomized 22 dogs (11 males and 11 females) into 5 different output groups for 2 months of ScNS: 0 mA (sham) (N=6), 0.25 mA (N=4), 1.5 mA (N=4), 2.5 mA (N=4) and 3.5 mA (N=4).
Results
As compared with baseline, the changes of the durations of PAT episodes per 48 hours were significantly different among different groups (sham, -5.0±9.5 s; 0.25 mA 95.5±71.0 s; 1.5 mA, -99.3±39.6 s; 2.5 mA, -155.3±87.8 s and 3.5 mA, -76.3±44.8 s, p<0.001). The 3.5 mA group had greater reduction of sinus heart rate than the sham group (-29.8±15.0 bpm vs -14.5±3.0 bpm, p=0.038). Immunohistochemical studies showed that the 0.25 mA group had a significantly increased while 2.5 mA and 3.5 mA stimulation had a significantly reduced growth-associated protein 43 nerve densities in both atria and ventricles. The plasma Norepinephrine concentrations in 0.25 mA group was 5063.0±4366.0 pg/ml, which was significantly higher than other groups of dogs (739.3±946.3, p=0.009). There were no significant differences in the effects of simulation between males and females.
Conclusions
In ambulatory dogs, low output ScNS causes cardiac nerve sprouting, increases plasma norepinephrine concentration and the duration of PAT episodes while high output ScNS is antiarrhythmic
Construction of optimal locally recoverable codes and connection with hypergraph
Locally recoverable codes are a class of block codes with an additional property called locality. A locally recoverable code with locality r can recover a symbol by reading at most r other symbols. Recently, it was discovered by several authors that a q-ary optimal locally recoverable code, i.e., a locally recoverable code achieving the Singleton-type bound, can have length much bigger than q + 1. In this paper, we present both the upper bound and the lower bound on the length of optimal locally recoverable codes. Our lower bound improves the best known result in [12] for all distance d ≥ 7. This result is built on the observation of the parity-check matrix equipped with the Vandermonde structure. It turns out that a parity-check matrix with the Vandermonde structure produces an optimal locally recoverable code if it satisfies a certain expansion property for subsets of Fq. To our surprise, this expansion property is then shown to be equivalent to a well-studied problem in extremal graph theory. Our upper bound is derived by an refined analysis of the arguments of Theorem 3.3 in [6]
Stability of Transonic Characteristic Discontinuities in Two-Dimensional Steady Compressible Euler Flows
For a two-dimensional steady supersonic Euler flow past a convex cornered
wall with right angle, a characteristic discontinuity (vortex sheet and/or
entropy wave) is generated, which separates the supersonic flow from the gas at
rest (hence subsonic). We proved that such a transonic characteristic
discontinuity is structurally stable under small perturbations of the upstream
supersonic flow in . The existence of a weak entropy solution and Lipschitz
continuous free boundary (i.e. characteristic discontinuity) is established. To
achieve this, the problem is formulated as a free boundary problem for a
nonstrictly hyperbolic system of conservation laws; and the free boundary
problem is then solved by analyzing nonlinear wave interactions and employing
the front tracking method.Comment: 26 pages, 3 figure
The contributions of components to the axial charges of proton and its resonances
We calculate the axial charges of the proton and its resonances in the
framework of the constituent quark model, which is extended to include the
components. If 20% admixtures of the components in
the proton are assumed, the theoretical value for the axial charge in our model
is in good agreement with the empirical value, which can not be well reproduced
in the traditional constituent quark model even though the symmetry breaking or relativistic effect is taken into account. We also
predict an unity axial charge for with 30%
components constrained by the strong and electromagnetic decays.Comment: 4 pages, 4 table
Experimental investigation of color reproduction quality of color 3D printing based on colored layer features
Color three-dimensional (3D) printing is an advanced 3D printing technique for reproducing colorful 3D objects, but it still has color accuracy issues. Plastic-based color 3D printing is a common color 3D printing process, and most factors affecting its color reproduction quality have been studied from printing materials to parameters in the fixed consecutive layers. In this work, and combined with variable stair thickness, the colored layer sequence in sliced layers of a specific 3D color test chart is deliberately changed to test the effects of colored layer features on its final color reproduction quality. Meanwhile, the colorimetric measurement and image acquisition of printed 3D color test charts are both achieved under standard conditions. Results clearly show that the chromatic aberration values and mean structural similarity (MSSIM) values of color samples have a significant correlation with the colored stair thickness, but both did not display a linear relationship. The correlation trends between colored layer sequence and the above two indexes are more localized to the colored stair thickness. Combined with color structural similarity (SSIM) maps analysis, a comprehensive discussion between colored layer features and color reproduction quality of color 3D printing is presented, providing key insights for developing further accurate numerical models
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