WEIGHT TRANSFER CHANGES DURING GOLF SHOTS FROM DIFFERENT LIES

The aim of the present study was to examine changes in weight transfer during golf shots from flat, uphill, and downhill lies. Twelve male amateur golfers with a mean handicap of 1.6 ± 2.4 hit a total of 30 golf shots from flat, downhill, and uphill lies. A computer assisted rehabilitation environment (CAREN) was used to collect 3D kinematics and kinetics and a Foresight GC2 launch monitor was used to measure performance outcomes (ball speed, launch angle, azimuth, side spin, and offline displacement). The mean position of the centre of pressure moved approximately 9.4% closer to the front foot for downhill lies and approximately 8.9% closer to the back foot for uphill lies. The speed of the ball was not significantly affected by the lie, but the distance the ball travelled was. An uphill lie encourages spin of the ball to the left, and may increase the risk of playing a hook shot

Quantum Blobs

Quantum blobs are the smallest phase space units of phase space compatible with the uncertainty principle of quantum mechanics and having the symplectic group as group of symmetries. Quantum blobs are in a bijective correspondence with the squeezed coherent states from standard quantum mechanics, of which they are a phase space picture. This allows us to propose a substitute for phase space in quantum mechanics. We study the relationship between quantum blobs with a certain class of level sets defined by Fermi for the purpose of representing geometrically quantum states.Comment: Prepublication. Dedicated to Basil Hile

ADJUSTMENT IN THE FLIGHT PHASE OF 1M SPRINGBOARD FORWARD PIKE DIVES

The aim of this study was to investigate the variability in 1m springboard forward pike dives (101B). Variability of body orientation angle at takeoff and water entry together with joint angle time histories of 15 forward pike dives, performed by an international diver, were determined using video analysis. A computer simulation model was used to investigate the effects of initial conditions variability and flight phase configuration variability on outcome (orientation at entry) variability. It was found that the variation in the simulated orientation at entry arising from variability in the initial conditions was greater than the actual variation. This indicates that the diver used feedback correction to make adjustments during flight to reduce the variability of his entry angle

A region segmentation method to measure multiple features using a tactile scanning probe

Coordinate measuring machines (CMMs) have been widely used in industry to precisely measure parts for inspection or quality control. One of the main barriers to using a CMM touch-trigger probe is the cumbersome programming work required to identify the probing points and for scan path planning. In this paper, we propose a practical data-segmentation method to continuously measure multiple features of the workpiece using a scanning probe. This approach takes advantage of the fast data-capture capability of the scanning probe and, subsequently, the point dataset is segmented using the information extracted from the CAD model of the part. This methodology does not require tedious programming and all desired measurement results can be obtained from a single scan. The principle of the method is presented, and the feasibility of the method is experimentally verified on a bridge-type Hexagon DEA Global CMM equipped with a Leitz LSP-X1 probe. The proposed method avoids manual operation errors and generates more sampling points than traditional methods; therefore, theoretically providing lower measurement uncertainty. The test results also indicate that the new method using a scanning probe is easy to implement and can save more than 90% measurement time in comparison with a conventional touch-trigger method

Antiferromagnetism at T > 500 K in the Layered Hexagonal Ruthenate SrRu2O6

We report an experimental and computational study of magnetic and electronic properties of the layered Ru(V) oxide SrRu2O6 (hexagonal, P-3 1m), which shows antiferromagnetic order with a N\'eel temperature of 563(2) K, among the highest for 4d oxides. Magnetic order occurs both within edge-shared octahedral sheets and between layers and is accompanied by anisotropic thermal expansivity that implies strong magnetoelastic coupling of Ru(V) centers. Electrical transport measurements using focused ion beam induced deposited contacts on a micron-scale crystallite as a function of temperature show p-type semiconductivity. The calculated electronic structure using hybrid density functional theory successfully accounts for the experimentally observed magnetic and electronic structure and Monte Carlo simulations reveals how strong intralayer as well as weaker interlayer interactions are a defining feature of the high temperature magnetic order in the material.Comment: Physical Review B 2015 accepted for publicatio

Clifford Algebras in Symplectic Geometry and Quantum Mechanics

The necessary appearance of Clifford algebras in the quantum description of fermions has prompted us to re-examine the fundamental role played by the quaternion Clifford algebra, C(0,2). This algebra is essentially the geometric algebra describing the rotational properties of space. Hidden within this algebra are symplectic structures with Heisenberg algebras at their core. This algebra also enables us to define a Poisson algebra of all homogeneous quadratic polynomials on a two-dimensional sub-space, Fa of the Euclidean three-space. This enables us to construct a Poisson Clifford algebra, H(F), of a finite dimensional phase space which will carry the dynamics. The quantum dynamics appears as a realization of H(F) in terms of a Clifford algebra consisting of Hermitian operators.Comment: 17 page

ADJUSTMENT IN THE TAKEOFF PHASE OF 1-M SPRINGBOARD FORWARD DIVES

The aim of this study was to investigate whether any adjustment is made during the board contact phase of 1-m springboard forward dives. Variability of body orientation angle at landing from hurdle (touchdown) and at takeoff together with joint angle time histories of 15 forward pike dive takeoffs, performed by an international diver, were determined using video analysis. A computer simulation model of a diver and springboard was used to determine the effects of perturbations of initial conditions on takeoff variability. The variation at takeoff obtained in the simulation outcome was much greater than in the actual performance, indicating that the diver made adjustments during the board contact phase. The diver varied his body configuration during the board recoil phase to adjust his body orientation, leading to low variability at takeoff