The Cosmic Lens All-Sky Survey parent population - I. Sample selection and number counts

We present the selection of the Jodrell Bank Flat-spectrum (JBF) radio source sample, which is designed to reduce the uncertainties in the Cosmic Lens All-Sky Survey (CLASS) gravitational lensing statistics arising from the lack of knowledge about the parent population luminosity function. From observations at 4.86 GHz with the Very Large Array, we have selected a sample of 117 flat-spectrum radio sources with flux densities greater than 5 mJy. These sources were selected in a similar manner to the CLASS complete sample and are therefore representative of the parent population at low flux densities. The vast majority (~90 per cent) of the JBF sample are found to be compact on the arcsecond scales probed here and show little evidence of any extended radio jet emission. Using the JBF and CLASS complete samples we find the differential number counts slope of the parent population above and below the CLASS 30 mJy flux density limit to be -2.07+/-0.02 and -1.96+/-0.12, respectively.Comment: 10 pages, 4 figures, accepted for publication in MNRA

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 $\Bbb R^n$. 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 $\mu$ of large random real symmetric matrices with heavy tailed entries. Specifically, consider the N by N symmetric matrix $Y_N^\sigma$ whose (i,j) entry is $\sigma(i/N,j/N)X_{ij}$ where $(X_{ij}, 0<i<j+1<\infty)$ is an infinite array of i.i.d real variables with common distribution in the domain of attraction of an $\alpha$-stable law, $0<\alpha<2$, and $\sigma$ is a deterministic function. For a random diagonal $D_N$ independent of $Y_N^\sigma$ and with appropriate rescaling $a_N$, we prove that the distribution $\mu$ of $a_N^{-1}Y_N^\sigma + D_N$ 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

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

Global classical solutions for partially dissipative hyperbolic system of balance laws

This work is concerned with ($N$-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

B0850+054: a new gravitational lens system from CLASS

We report the discovery of a new gravitational lens system from the CLASS survey. Radio observations with the VLA, the WSRT and MERLIN show that the radio source B0850+054 is comprised of two compact components with identical spectra, a separation of 0.7 arcsec and a flux density ratio of 6:1. VLBA observations at 5 GHz reveal structures that are consistent with the gravitational lens hypothesis. The brighter of the two images is resolved into a linear string of at least six sub-components whilst the weaker image is radially stretched towards the lens galaxy. UKIRT K-band imaging detects an 18.7 mag extended object, but the resolution of the observations is not sufficient to resolve the lensed images and the lens galaxy. Mass modelling has not been possible with the present data and the acquisition of high-resolution optical data is a priority for this system.Comment: 5 pages, 4 figures, accepted for publication in MNRA