The use of in-situ deployments to examine the success of water quality mitigation measures on a watercress farm

Watercress has long been believed to affect macroinvertebrate communities in chalk streams. Harvesting and washing watercress damages plant tissues and releases isothiocyanates which are potential toxicants to Gammarus pulex (L.). This study examined whether impacts on G. pulex of watercress farm factory wash water could be mitigated by treating via recirculation through the watercress beds

Friction at the tennis shoe-court interface: how biomechanically informed lab-based testing can enhance understanding

This paper presents some of the methodology, observations and findings from a 30-month study, aiming to improve the understanding of tennis shoe-court interactions and the biomechanical implications of changes in friction between the shoe and surface. A detailed programme of biomechanical player testing on different court surfaces provided the boundary conditions with which to develop a lab-based rig capable of simulating the key aspects of shoe-surface interaction that are required for acceptable performance (e.g. push-off to accelerate) within expected levels of consistency (e.g. for a controlled slide). Large- scale parametric testing could then be carried out for a variety of surface types and components under a range of loading conditions, without the risk of injury to human participants. Two case studies are described to demonstrate the value of a combined approach of biomechanical field testing and lab-based rigs that simulate shoe-court interactions. These include a study that compared different artificial clay court designs; and a study that examined the effect of different acrylic hard court parameters on friction and the tribological mechanisms that explain the observed interactio

Effect of varying the volume infill sand on synthetic clay surfaces in terms of the shoe-surface friction

The friction developed by the shoe-surface interface on artificial clay has not been widely studied, and can influence player's performance and injury risk. The aim of this research was to investigate the effect of varying the quantity of infill sand on shoe- surface friction on an artificial clay court tennis surface. A laboratory-based mechanical test rig was used to measure the friction force developed at the shoe-surface interface. Additionally, the perception of a group of participants, performing a turning movement on the same surface under dry conditions, was collected in order to compare against the mechanical results. The relationship between the normal force and friction generated by the shoe-surface interaction was examined for surfaces with different sand in-fill volumes. The mechanical testing was performed under dry and wet conditions, showing strong and significant differences. Results indicated that the normal force significantly influenced the static and dynamic frictional forces. For lower sand infill volumes, as normal loading increased, the dry condition was found to exhibit the lowest peak static friction force and highest average dynamic friction force. However, for higher sand infill volume conditions, the opposite behaviour was observed. Strong and significant positive linear relationships were found between peak friction force and average dynamic friction force for all infill sand volumes and conditions. The mechanical results were in agreement with the perception data, which suggests that the participants were sensitive to the small changes in sand infill volumes. The findings of this study will therefore aid the understanding of tennis players’ perceived response to a tennis court surface. In order to get a better understanding of friction behaviour, further testing needs to be performed, and once the mechanisms involved are understood, surface properties could be modified to increase performance and reduce injury risk

Ion milling - the perfect cross-section of a painted textile

The successful study and conservation of historical objects is greatly enhanced by accurate materials analysis. Here embedded cross-sections from a processional marching banner were viewed by scanning electron microscopy (SEM) pre and post ion milling The application of ion-milling to the resin embedded cross-sections of the painted textile improved the sample surface resulting in greatly enhanced SEM images by producing clear distinctions between layers. It also enabled clear images which show the areas where ingress of the ground paint layer had seeped into the textile support in some areas and not on others. This perhaps indicates deliberate differences in the preparation layer depending on the type of final painting layer or it could simply be due to a lack of accuracy in its application prior to painting. The analysis of cross-section samples from painted textiles often includes the textile itself making sample preparation more complex due to the possibility of fraying of the textile during sample polishing; the ion-milling technique prevented this from occurring. To enhance findings further analysis on these ion milled cross-section samples by the use of mapping spectroscopic techniques such as Fourier transform infrared spectroscopy (FTIR) and Raman would facilitate material identification of the layers

The Coupling of Yang-Mills to Extended Objects

The coupling of Yang-Mills fields to the heterotic string in bosonic formulation is generalized to extended objects of higher dimension (p-branes). For odd p, the Bianchi identities obeyed by the field strengths of the (p+1)-forms receive Chern-Simons corrections which, in the case of the 5-brane, are consistent with an earlier conjecture based on string/5-brane duality.Comment: 14 Page

Chern-Simons forms, Mickelsson-Faddeev algebras and the p-branes

In string theory, nilpotence of the BRS operator \d for the string functional relates the Chern-Simons term in the gauge-invariant antisymmetric tensor field strength to the central term in the Kac-Moody algebra. We generalize these ideas to p-branes with odd p and find that the Kac-Moody algebra for the string becomes the Mickelsson-Faddeev algebra for the p-brane.Comment: 11 pages, CTP-TAMU-45-92, (Correction of some minor sign errors and typos