830 research outputs found
Spontaneous fourfold-symmetry breaking driven by electron-lattice coupling and strong correlations in high- cuprates
Using dynamical-mean-field theory for clusters, we study the two-dimensional
Hubbard model in which electrons are coupled with the orthorhombic lattice
distortions through the modulation in the hopping matrix. Instability towards
spontaneous symmetry breaking from a tetragonal symmetric phase to an
orthorhombic distorted phase is examined as a function of doping and
interaction strength. A very strong instability is found in the underdoped
pseudogap regime when the interaction strength is large enough to yield the
Mott insulating phase at half filling. The symmetry breaking accompanies the
recovery of quasiparticle weights along one of the two antinodal directions,
leading to the characteristic Fermi arc reconnection. We discuss the
implications of our results to the fourfold symmetry breaking reported in
systems where the underlying crystal does not have any structural anisotropy.Comment: 6 pages with 4 figure
Temporal shape super-resolution by intra-frame motion encoding using high-fps structured light
One of the solutions of depth imaging of moving scene is to project a static
pattern on the object and use just a single image for reconstruction. However,
if the motion of the object is too fast with respect to the exposure time of
the image sensor, patterns on the captured image are blurred and reconstruction
fails. In this paper, we impose multiple projection patterns into each single
captured image to realize temporal super resolution of the depth image
sequences. With our method, multiple patterns are projected onto the object
with higher fps than possible with a camera. In this case, the observed pattern
varies depending on the depth and motion of the object, so we can extract
temporal information of the scene from each single image. The decoding process
is realized using a learning-based approach where no geometric calibration is
needed. Experiments confirm the effectiveness of our method where sequential
shapes are reconstructed from a single image. Both quantitative evaluations and
comparisons with recent techniques were also conducted.Comment: 9 pages, Published at the International Conference on Computer Vision
(ICCV 2017
Confidence intervals of prediction accuracy measures for multivariable prediction models based on the bootstrap-based optimism correction methods
In assessing prediction accuracy of multivariable prediction models, optimism
corrections are essential for preventing biased results. However, in most
published papers of clinical prediction models, the point estimates of the
prediction accuracy measures are corrected by adequate bootstrap-based
correction methods, but their confidence intervals are not corrected, e.g., the
DeLong's confidence interval is usually used for assessing the C-statistic.
These naive methods do not adjust for the optimism bias and do not account for
statistical variability in the estimation of parameters in the prediction
models. Therefore, their coverage probabilities of the true value of the
prediction accuracy measure can be seriously below the nominal level (e.g.,
95%). In this article, we provide two generic bootstrap methods, namely (1)
location-shifted bootstrap confidence intervals and (2) two-stage bootstrap
confidence intervals, that can be generally applied to the bootstrap-based
optimism correction methods, i.e., the Harrell's bias correction, 0.632, and
0.632+ methods. In addition, they can be widely applied to various methods for
prediction model development involving modern shrinkage methods such as the
ridge and lasso regressions. Through numerical evaluations by simulations, the
proposed confidence intervals showed favourable coverage performances. Besides,
the current standard practices based on the optimism-uncorrected methods showed
serious undercoverage properties. To avoid erroneous results, the
optimism-uncorrected confidence intervals should not be used in practice, and
the adjusted methods are recommended instead. We also developed the R package
predboot for implementing these methods (https://github.com/nomahi/predboot).
The effectiveness of the proposed methods are illustrated via applications to
the GUSTO-I clinical trial
Analytical investigations of thermodynamic effect on cavitation characteristics of sheet and tip leakage vortex cavitation
Vapor production in cavitation extracts the latent heat of evaporation from the surrounding liquid, which decreases the local temperature, and hence the local vapor pressure in the vicinity of cavity. This is called thermodynamic/thermal effect of cavitation. In the present study, the thermodynamic effect on cavitation characteristics such as cavitation compliance and mass flow gain factor, which are known to be important parameters for cavitation instabilities appearing in turbopumps, were studied. Main cavitations in turbopumps, blade and tip leakage vortex cavitations were separately analyzed by simple analytical methods developed based on the potential flow theory, taking account of the latent heat extraction and heat transfer between the cavity and the surrounding fluid. The cavitation characteristics were estimated for the partial cavity and the tip leakage vortex cavity, and the thermodynamic effects on those characteristics were discussed.http://deepblue.lib.umich.edu/bitstream/2027.42/84240/1/CAV2009-final40.pd
Royal Jelly Facilitates Restoration of the Cognitive Ability in Trimethyltin-Intoxicated Mice
Trimethyltin (TMT) is a toxic organotin compound that induces acute neuronal death selectively in the hippocampal dentate gyrus (DG) followed by cognition impairment; however the TMT-injured hippocampal DG itself is reported to regenerate the neuronal cell layer through rapid enhancement of neurogenesis. Neural stem/progenitor cells (NS/NPCs) are present in the adult hippocampal DG, and generate neurons that can function for the cognition ability. Therefore, we investigated whether royal jelly (RJ) stimulates the regenerating processes of the TMT-injured hippocampal DG, and found that orally administered RJ significantly increased the number of DG granule cells and simultaneously improved the cognitive impairment. Furthermore, we have already shown that RJ facilitates neurogenesis of cultured NS/NPCs. These present results, taken together with previous observations, suggest that the orally administered RJ may be a promising avenue for ameliorating neuronal function by regenerating hippocampal granule cells that function in the cognition process
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