The clubhead and hand planes in golf draw and fade shots.

Swing planes in golf have become a popular area of research. Cochran and Stobbs (1968) examined the motion of the clubhead and hands qualitatively. Subsequent quantitative analyses have included investigations of the planarity of the whole club (Coleman & Anderson, 2007) and clubhead (Shin, Casebolt, Lambert, Kim, & Kwon, 2008). The aim of this study was to investigate the motion of the clubhead and hands in the downswing quantitatively, and to compare these motions for the fade and draw (as suggested by Coleman and Anderson, 2007). In conclusion, both the clubhead and hand planes in the late downswing were found to differ significantly in relation to the target line between the draw and fade shots. Greater differences were found between golfers, rather than between shots, in the relationship between the clubhead and hand motion during the downswing. Nevertheless, further detailed analysis is warranted of how the motions around impact – especially the clubface orientation – differ between the two types of shot

The clubhead swing plane in golf draw and fade shots

It has become popular to characterise a golf shot in terms of a ‘swing plane’. However Coleman and Anderson (2007) showed that the motion of the whole club in the downswing could not be represented by a single plane in all players. Shin et al. (2008) found that the clubhead motion was consistently planar between the club being horizontal in the downswing and follow-through. Coleman and Anderson (2007) also suggested that the club plane might differ between draw and fade shots. The purpose of this study was to compare draw and fade shots, with a focus on the clubhead motion in the late downswing. The late downswing clubhead plane differs between a draw and a fade shot, even when differences in address angles are accounted for

Measurement of Newtonian fluid slip using a torsional ultrasonic oscillator

The composite torsional ultrasonic oscillator, a versatile experimental system, can be used to investigate slip of Newtonian fluid at a smooth surface. A rigorous analysis of slip-dependent damping for the oscillator is presented. Initially, the phenomenon of finite surface slip and the slip length are considered for a half-space of Newtonian fluid in contact with a smooth, oscillating solid surface. Definitions are revisited and clarified in light of inconsistencies in the literature. We point out that, in general oscillating flows, Navier's slip length b is a complex number. An intuitive velocity discontinuity parameter of unrestricted phase is used to describe the effect of slip on measurement of viscous shear damping. The analysis is applied to the composite oscillator and preliminary experimental work for a 40 kHz oscillator is presented. The Non-Slip Boundary Condition (NSBC) has been verified for a hydrophobic surface in water to within ~60 nm of |b|=0 nm. Experiments were carried out at shear rate amplitudes between 230 and 6800 /s, corresponding to linear displacement amplitudes between 3.2 and 96 nm.Comment: Revised with minor edits for revie

Structural Examination of Au/Ge(001) by Surface X-Ray Diffraction and Scanning Tunneling Microscopy

The one-dimensional reconstruction of Au/Ge(001) was investigated by means of autocorrelation functions from surface x-ray diffraction (SXRD) and scanning tunneling microscopy (STM). Interatomic distances found in the SXRD-Patterson map are substantiated by results from STM. The Au coverage, recently determined to be 3/4 of a monolayer of gold, together with SXRD leads to three non-equivalent positions for Au within the c(8x2) unit cell. Combined with structural information from STM topography and line profiling, two building blocks are identified: Au-Ge hetero-dimers within the top wire architecture and Au homo-dimers within the trenches. The incorporation of both components is discussed using density functional theory and model based Patterson maps by substituting Germanium atoms of the reconstructed Ge(001) surface.Comment: 5 pages, 3 figure

THE EFFECTS OF AUGMENTED BIOFEEDBACK ON NOVEL MOTOR-TASK LEARNING

Biofeedback has been shown to be an influential part of skill acquisition and performance, however, the use of biofeedback for novice, sports specific skill learning has not been assessed. Non-rowers (n=3) performed a 10-minute, novel-rowing task, where joint and rowing ergometer kinematics recorded. Following six non-instructed, subjective reinforcement sessions, participants completed a further six sessions whilst receiving real-time biofeedback. The results show that all subjects changed their rowing technique, moving towards the pattern prescribed by the biofeedback intervention. The elbow remained in greater extension until later in the pull, which induced changes in the temporal aspects of both knee and lumbar spine kinematics

EFFECTS OF NON-INSTRUCTED PRACTICE ON A NOVEL ROWING TASK

Information feedback has been shown to be an important part of the learning process, yet changes have not been assessed within sporting applications. Non-rowers (n=7) performed a 10-minute novel rowing task, and joint and rowing ergometer kinematics recorded. Following four non-instructed practice rowing sessions, their techniques were reassessed. Results showed that the ergometer handle trajectory became more elliptical throughout the stroke and that the knees were more flexed at catch (11°) and more extended at the finish (13°). Changes in the shape of the handle trajectory caused changes in the lengths of the pull and recovery phases and implied changes in the timing of joint motions. This study is a step towards understanding the motor learning of novices

THE EFFECTS OF CONCURRENT BIOFEEDBACK ON ROWING PERFORMANCE

The aim of this study was to assess the effects of concurrent biofeedback (BFb) on the ability of skilled rowers to modify the relative motions of their elbow and knee joints during ergometer rowing. Over 2 weeks, BFb (n=7) and control (n=7) participants completed two maximal rowing tasks (pre-intervention; transfer) separated by three submaximal rowing sessions supplemented with BFb for the BFb group. Pre-intervention to transfer session patterns showed increased elbow extension and knee flexion in the early phases of the pull, which was a move towards the pattern advocated by the BFb intervention. Although these alterations were not universal, BFb appears to be a useful training aid for those further from the target movement pattern

THE EFFECT OF BUNGEE TENSION ON POWER PROFILING IN KAYAK ERGOMETRY

In water sports, where accurate biomechanical measurement in situ is difficult, ergometers are frequently used to test athletes. Many kayak ergometer designs involve a bungee to assist in returning the athlete/paddle to the correct position for the next stroke. The study’s aim was to investigate the effect of bungee tension on the ergometermeasured maximal power-velocity profile of three experienced male kayak athletes. Bungee tension influenced the power-velocity profile, reducing peak power measured by up to 328.4 W from optimal to least optimal tension. Athlete’s anecdotally preferred feel tensions may be optimal, thus these tensions should be considered in investigating power-related factors