2,681 research outputs found
Epitaxial growth and the magnetic properties of orthorhombic YTiO3 thin films
High-quality YTiO3 thin films were grown on LaAlO3 (110) substrates at low
oxygen pressures (<10-8 Torr) using pulsed laser deposition. The in-plane
asymmetric atomic arrangements at the substrate surface allowed us to grow
epitaxial YTiO3 thin films, which have an orthorhombic crystal structure with
quite different a- and b-axes lattice constants. The YTiO3 film exhibited a
clear ferromagnetic transition at 30 K with a saturation magnetization of about
0.7 uB/Ti. The magnetic easy axis was found to be along the [1-10] direction of
the substrate, which differs from the single crystal easy axis direction, i.e.,
[001].Comment: 14 pages, 4 figure
Nonexistence of self-similar singularities for the 3D incompressible Euler equations
We prove that there exists no self-similar finite time blowing up solution to
the 3D incompressible Euler equations. By similar method we also show
nonexistence of self-similar blowing up solutions to the divergence-free
transport equation in . This result has direct applications to the
density dependent Euler equations, the Boussinesq system, and the
quasi-geostrophic equations, for which we also show nonexistence of
self-similar blowing up solutions.Comment: This version refines the previous one by relaxing the condition of
compact support for the vorticit
PRE- AND POST-IMPACT BALL AND RACQUET CHARACTERISTICS DURING TENNIS SERVES PERFORMED BY ELITE MALE AND FEMALE PLAYERS
This study quantified the pre- and post-impad 3-D kinematics of a tennis ball and racquet. Data were collected during the tennis competition of the 1996 Atlanta Olympic Games using two high-speed cameras (200 Hz). Two first serves were analysed for each subject. A one-way ANOVA for the factor of sex (p < .05) was performed for each parameter. The results indicate that, regardless of sex, the ball travelled forward and to the lefl during the flight phase before impact and the ball was hit near the peak height of the racquet. The males had significantly higher height of ball impact, greater pre-impad racquet velocity and greater post-impact ball velocity than their female counterparts. It is not certain whether the techniques used by males and females contributed to the differences in racquet speed observed
Spectral measure of heavy tailed band and covariance random matrices
We study the asymptotic behavior of the appropriately scaled and possibly
perturbed spectral measure of large random real symmetric matrices with
heavy tailed entries. Specifically, consider the N by N symmetric matrix
whose (i,j) entry is where is an infinite array of i.i.d real variables with common
distribution in the domain of attraction of an -stable law,
, and is a deterministic function. For a random diagonal
independent of and with appropriate rescaling , we
prove that the distribution of converges in
mean towards a limiting probability measure which we characterize. As a special
case, we derive and analyze the almost sure limiting spectral density for
empirical covariance matrices with heavy tailed entries.Comment: 31 pages, minor modifications, mainly in the regularity argument for
Theorem 1.3. To appear in Communications in Mathematical Physic
KINEMATIC COMPARISON OF TWO RACING WHEELCHAIR PROPULSION TECHNIQUES
The purpose of this study was to quantify selected 3-D kinematic characteristics of the upper body during racing wheelchair stroking over a roller system using the conventional technique (CVT) and para-backhand technique (PBT). Eight CVT and seven PBT users served as the subjects. Each subject performed maximum effort stroking for 30 s at two loads and was recorded by two S-VHS camcorders (60 Hz). The CVT was found to have significant shorter push time, smaller relative push time, and greater relative recovery time than the PBT. Significant difference in arm position at the instant of hand release was found between the two techniques and the difference may have implications for the stress placed on the structures around the shoulder joint. When compared to each other, the CVT is a more compact stroke and the PBT has a faster overall movement speed
Global classical solutions for partially dissipative hyperbolic system of balance laws
This work is concerned with (-component) hyperbolic system of balance laws
in arbitrary space dimensions. Under entropy dissipative assumption and the
Shizuta-Kawashima algebraic condition, a general theory on the well-posedness
of classical solutions in the framework of Chemin-Lerner's spaces with critical
regularity is established. To do this, we first explore the functional space
theory and develop an elementary fact that indicates the relation between
homogeneous and inhomogeneous Chemin-Lerner's spaces. Then this fact allows to
prove the local well-posedness for general data and global well-posedness for
small data by using the Fourier frequency-localization argument. Finally, we
apply the new existence theory to a specific fluid model-the compressible Euler
equations with damping, and obtain the corresponding results in critical
spaces.Comment: 39 page
THE EFFECTS OF WEARING SPANDEX PANTS ON IMPACT FORCES AND MUSCLE ACTIVITY DURING DROP LANDING
INTRODUCTION: Nigg and Wakeling (2001) proposed that repetitive impact force are not an important form an injury perspective but are the reason for change in muscle activity to minimize soft tissue vibrations. Doan et al. (2003) found that wearing compressive shorts reduced muscle oscillation on landing and concluded that this may have benefit in terms of reduced tissue injury. If wearing spandex pants may tune the muscle to minimize vibration, there is specific adjustment made to reduce joint loading because subsequent changes in muscle activity would change joint stiffness. Since actual effect of wearing spandex pants on muscle activity and impact force are not established, the purpose of this study were to determine how spandex pants affect impact force and muscle activities in the lower extremity
Improved Iterative Coordinated Beamforming Based on Singular Value Decomposition for Multiuser Mimo Systems With Limited Feedforward
Coordinated beamforming based on singular value decomposition is an iterative method to jointly optimize thetransmit beamformers and receive combiners, to achieve high levels of sum rates in the downlink of multiusersystems, by exploiting the multi-dimensional wireless channel created by multiple transmit and receive antennas. The optimization is done at the base station and the quantized beamformers are sent to the users through a low rate link.In this work, we propose to optimize this algorithm by reducing the number of iterations and improving its uncoded bit error rate performance. Simulation results show that our proposal achieves a better bit error rate with a lower number of iterations than the original algorithm
A compact and reconfigurable silicon nitride time-bin entanglement circuit
Photonic chip based time-bin entanglement has attracted significant attention
because of its potential for quantum communication and computation. Useful
time-bin entanglement systems must be able to generate, manipulate and analyze
entangled photons on a photonic chip for stable, scalable and reconfigurable
operation. Here we report the first time-bin entanglement photonic chip that
integrates time-bin generation, wavelength demultiplexing and entanglement
analysis. A two-photon interference fringe with an 88.4% visibility is measured
(without subtracting any noise), indicating the high performance of the chip.
Our approach, based on a silicon nitride photonic circuit, which combines the
low-loss characteristic of silica and tight integration features of silicon,
paves the way for scalable real-world quantum information processors.Comment: 4 pages, 5 figure
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