15,069 research outputs found
Sharp Cusa and Becker-Stark inequalities
We determine the best possible constants θ,ϑ,α and β such that the inequalities ((2+cosx)/3)^θ < sinx/x < ((2+cosx)/3)^ϑ and ((π^2)/(π^2-4×^2))^α < tan×/× < ((π^2)/(π^2-4×^2))^β are valid for 0 < × < π/2. Our results sharpen inequalities presented by Cusa, Becker and Stark.published_or_final_versio
Elastic Wave Scattering and Dynamic Stress Concentrations in Stretching Thick Plates with Two Cutouts by Using the Refined Dynamic Theory
Based on the refined dynamic equation of stretching plates, the elastic tension–compression wave scattering and dynamic stress concentrations in the thick plate with two cutouts are studied. In view of the problem that the shear stress is automatically satisfied under the free boundary condition, the generalized stress of the first-order vanishing moment of shear stress is considered. The numerical results indicate that, as the cutout is thick, the maximum value of the dynamic stress factor obtained using the refined dynamic theory is 19% higher than that from the solution of plane stress problems of elastic dynamics
Sharpness of Wilker and Huygens type inequalities
We present an elementary proof of Wilker's inequality involving trigonometric functions, and establish sharp Wilker and Huygens type inequalities. Mathematics Subject Classification 2010: 26D05.published_or_final_versio
Temporal HeartNet: Towards Human-Level Automatic Analysis of Fetal Cardiac Screening Video
We present an automatic method to describe clinically useful information
about scanning, and to guide image interpretation in ultrasound (US) videos of
the fetal heart. Our method is able to jointly predict the visibility, viewing
plane, location and orientation of the fetal heart at the frame level. The
contributions of the paper are three-fold: (i) a convolutional neural network
architecture is developed for a multi-task prediction, which is computed by
sliding a 3x3 window spatially through convolutional maps. (ii) an anchor
mechanism and Intersection over Union (IoU) loss are applied for improving
localization accuracy. (iii) a recurrent architecture is designed to
recursively compute regional convolutional features temporally over sequential
frames, allowing each prediction to be conditioned on the whole video. This
results in a spatial-temporal model that precisely describes detailed heart
parameters in challenging US videos. We report results on a real-world clinical
dataset, where our method achieves performance on par with expert annotations.Comment: To appear in MICCAI, 201
Diastolic funciton correlates with the degree of iron overload in patients with haemoglobin H disease
published_or_final_versio
Holographic Superconductors from Einstein-Maxwell-Dilaton Gravity
We construct holographic superconductors from Einstein-Maxwell-dilaton
gravity in 3+1 dimensions with two adjustable couplings and the charge
carried by the scalar field. For the values of and we
consider, there is always a critical temperature at which a second order phase
transition occurs between a hairy black hole and the AdS RN black hole in the
canonical ensemble, which can be identified with the superconducting phase
transition of the dual field theory. We calculate the electric conductivity of
the dual superconductor and find that for the values of and where
is small the dual superconductor has similar properties to the
minimal model, while for the values of and where is
large enough, the electric conductivity of the dual superconductor exhibits
novel properties at low frequencies where it shows a "Drude Peak" in the real
part of the conductivity.Comment: 25 pages, 13 figures; v2, typos corrected; v3, refs added, to appear
in JHE
The removal of thermally aged films of triacylglycerides by surfactant solutions
Thermal ageing of triacylglycerides (TAG) at high temperatures produces films which resist removal using aqueous surfactant solutions. We used a mass loss method to investigate the removal of thermally aged TAG films from hard surfaces using aqueous solutions of surfactants of different charge types. It was found that cationic surfactants are most effective at high pH, whereas anionics are most effective at low pH and a non-ionic surfactant is most effective at intermediate pH. We showed that the TAG film removal process occurs in several stages. In the first ‘‘lag phase’’ no TAG removal occurs; the surfactant first partitions into the thermally aged film. In the second stage, the TAG film containing surfactant was removed by solubilisation into micelles in the aqueous solution. The effects of pH and surfactant charge on the TAG removal process correlate with the effects of these variables on the extent of surfactant partitioning to the TAG film and on the maximum extent of TAG solubilisation within the micelles. Additionally, we showed how the TAG removal is enhanced by the addition of amphiphilic additives such as alcohols which act as co-surfactants. The study demonstrates that aqueous surfactant solutions provide a viable and more benign alternative to current methods for the removal of thermally aged TAG films
Refractive index in holographic superconductors
With the probe limit, we investigate the behavior of the electric
permittivity and effective magnetic permeability and related optical properties
in the s-wave holographic superconductors. In particular, our result shows that
unlike the strong coupled systems which admit a gravity dual of charged black
holes in the bulk, the electric permittivity and effective magnetic
permeability are unable to conspire to bring about the negative
Depine-Lakhtakia index at low frequencies, which implies that the negative
phase velocity does not appear in the holographic superconductors under such a
situation.Comment: JHEP style, 1+15 pages, 11 figures, version to appear in JHE
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