Ground reaction force measures when running in soccer boots and soccer training shoes on a natural turf surface

There are differences in ground reaction force when wearing soccer boots compared with training shoes on a natural turf surface. Two natural-turf-covered force platforms, located outdoors in a field, allowed comparison of performance when six-studded soccer boots and soccer training shoes were worn during straight fast running (5.4 m s^-1 ± 0.27 m s-1) and slow running (4.4 m^s-1 ± 0.22 m s^-1). Six male soccer players (mean age: 25 ± 4.18 years; mean mass 79.7 ±9.32 kg) struck the first platform with the right foot and the second platform with the left foot. In fast running, the mean vertical impact peak was significantly greater in soccer boots (2.706 BW) than in training shoes (2.496 BW) when both the right and left foot were considered together and averaged (P = 0.003). Similarly, the mean vertical impact peak loading rate was greater when wearing soccer boots at 26.09 BWs^-1 compared to training shoes (21.32 BWs^-1;P = 0.002). Notably, the mean vertical impact peak loading rate of the left foot (boots: 28.07 BWs^-1; shoes: 22.52 BWs^-1) was significantly greater than the right foot (boots: 24.11 BWs^-1; shoes: 20.11 BWs^-1) in both boots and shoes (P = 0.018). The braking force was greater for the left foot (P = 0.013). In contrast, mean peak vertical propulsion forces were greater for the right foot (P > 0.001) when either soccer boots or training shoes were considered. Similar significant trends were evident in slow running, and, notably, in both soccer boots and training shoes medial forces were greater for the left foot (P = 0.008) and lateral forces greater for the right foot (P = 0.011). This study showed the natural turf ground reaction force measurement system can highlight differences in footwear in an ecological environment. Greater forces and impact loading rates occurred during running activity in soccer boots than in training shoes, with soccer boots showing reduced shock attenuation at impact. Such findings may have implications for impact-related injuries with sustained exposure, especially on harder natural-turf surfaces. There were differences in the forces occurring at the right and left feet with the ground, thus suggesting the use of bipedal monitoring of ground reaction forces.     

The playing performance of county cricket pitches

The surface on to which a bowler projects a ball in the game of cricket is made up of hard packed soil with sparse grass cover. This natural turf pitch is of fundamental importance to the play of the game and the quality of the surface is a prime concern of players, officials, commentators and spectators alike. A programme of research has been undertaken to identify the factors that lead to the construction of high quality cricket pitches. This work employed the technology of highspeed video analysis to monitor the performance of first class cricket pitches during county matches. A system for measuring the impact of a cricket ball on a pitch was developed, and over 3000 ball impacts analysed. This analysis enabled pitches to be characterized in terms of pace, bounce and consistency. Soil properties for the monitored pitches were identified and correlations were drawn between pitch performance and soil composition.     

The Vice: Some Historically Inspired and Proof-Generated Steps to Limits of Sequences

This paper proposes a genetic development of the concept of limit of a sequence leading to a definition, through a succession of proofs rather than through a succession of sequences or a succession of εs. The major ideas on which it is based are historical and depend on Euclid, Archimedes, Fermat, Wallis and Newton. Proofs of equality by means of inequalities precede the notion of limit. For example, the determination of the volume of a pyramid precedes the definition of limit. The algebraic details given here are anachronistically modern, and the notion of a vice between two inequalities which provides the distinctive perspective of this paper would not have been recognized in this form by any of the named mathematicians since it presumes the existence of negative numbers and their comparability in a modern sense with positive numbers.     

Colour-based rigid body tracking using three-dimensional graphics models

This paper introduces the first stage of a new model-based approach to three-dimensional (3D) human movement tracking. A ‘generate-and-test’ matching procedure was adopted by matching rendered images of a 3D computer graphics model of the human body to target images of rigid body motion. The set of pixels to be compared were just those corresponding to the model of the body in the rendered images. The matching criterion to optimize model position and orientation was based on the minimisation of the RGB (red-green-blue) colour difference between generated model images and associated target images. The method was able to track synthetic image sequences of a half twisting somersault accurately with root-mean-square (rms) errors of less than 5 mm and 0.3∘ for position and orientation estimates respectively. The suitability of the proposed approach for rigid body motion tracking was supported by additional tracking experiments on video image sequences of ‘wooden cross’ trajectories. Comparisons of tracked estimates against manual digitizing estimates returned relatively small rms difference values on both side somersault and twisting somersault movements. The proposed approach has the potential to track video images of a human torso using a rigid body model and hence to track articulated movements by successively adding segments to the model in a hierarchical manner.     

Writing from the archive: Henry Garnet’s powder-plot letters and archival communication

Through a reading of the archived letters of Henry Garnet (1555–1606), Superior of the Jesuit order in England and suspected Gunpowder plotter, this article investigates the nature of the archive in relation to narrative theory. Figuring the archive as one of the number of narrating voices accrued by the individual record, I argue that models of communication such as those put forward by Roman Jakobson, Wayne C. Booth and Seymour Chatman afford useful insights into the ways in which power is inscribed and reinscribed in the record through successive acts of reading and rewriting.