We found an insignificant change in ACL laxity from follicular to luteal phases of the menstrual cycle. This indicates that no single phase of the menstrual cycle clinically affects the ACL more than the next. Although the presence of sex hormones-particularly estrogen-may indeed predispose females to higher ACL injury rates, we did not find any evidence that hormonal level changes equate with significant ACL laxity changes. We conclude that the menstrual cycle does not significantly affect ACL laxity in the competitive adolescent female athlete.

Autonomous survey vessels can increase the efficiency and availability of wide-area river environment surveying as a tool for environment protection and conservation. A key challenge is the accurate localisation of the vessel, where bank-side vegetation or urban settlement preclude the conventional use of line-of-sight global navigation satellite systems (GNSS). In this paper, we evaluate unaided visual odometry, via an on-board stereo camera rig attached to the survey vessel, as a novel, low-cost localisation strategy. Feature-based and appearance-based visual odometry algorithms are implemented on a six degrees of freedom platform operating under guided motion, but stochastic variation in yaw, pitch and roll. Evaluation is based on a 663 m-long trajectory (>15,000 image frames) and statistical error analysis against ground truth position from a target tracking tachymeter integrating electronic distance and angular measurements. The position error of the feature-based technique (mean of ±0.067 m) is three times smaller than that of the appearance-based algorithm. From multi-variable statistical regression, we are able to attribute this error to the depth of tracked features from the camera in the scene and variations in platform yaw. Our findings inform effective strategies to enhance stereo visual localisation for the specific application of river monitoring.

Using pressure transducers in soil surfaces prepared in controlled conditions, the vertical stress was recorded at 100 mm, 200 mm, and 350 mm depth within two soil surfaces of 1460 kg/m 3 and 1590 kg/m 3 for five subjects of 747-843 N body weight running at 4 m/s (5 per cent). Simultaneous in-shoe pressure data were collected to investigate the influence of soil density on loading experienced by the player and to provide information on the load applied to the surface. For each soil density, the subjects wore three different footwear types: soccer boots with traditional studs, boots with moulded studs, and boots designed for synthetic turf. For the mean of all subjects, there was no significant difference in the maximum vertical soil stress or loading rate between surfaces at any depth but within each surface there was a significant reduction of 32 kPa between -100 mm and the other depths. The peak loading rate was two orders of magnitude greater at -100 mm than at -200 mm or -350 mm. The variation in maximum vertical stress at -100 mm for different subjects was significant (p < 0.001) and increased with increasing subject weight (R 2 ¼ 0.87); at -200 mm and -350 mm there was no significant subject or density effect; a similar pattern was observed with the peak loading rate, with a linear relationship between the loading rate and the subject weight. In-shoe pressure data revealed no significant differences in the peak force or loading rate between surfaces, but a significantly lower heel pressure for the soft (1460 kg/m 3 ) surface compared with the hard (1590 kg/m 3 ) surface (p < 0.05). Wearing of different footwear had no influence on the peak force or pressure but revealed a lower rate of loading of force for the moulded boot than for the studded boot when performing on the hard surface. There was a low and non-significant relationship between the peak input force and the peak force experienced within the surface (R 2 ¼ 0.01; p > 0.05), however, peak resultant pressure data were used successfully to model the vertical stress distribution during running using a linear elastic model of soil behaviour. This novel approach to understanding the behaviour of the soil surface and the player has revealed a complex relationship between the input load and the load experienced by the surface. Future models will seek to understand this relationship further.

The reported research work was a multi-disciplinary, collaborative effort. Author SPD is the lead researcher and author of this manuscript. A detailed literature review and information regarding the ROP of lactide in the literature was conducted by author SPD as part of his doctoral thesis. Authors SPD, VM, HAA, JLB and KB contributed to the development of detailed study for the state-of-the art in the field of chronological development in the field of PLA processing. The author's contributed equally for making the manuscript more scientific and meaningful in terms of English language.

PLA is one of the most promising bio-compostable and bio-degradable thermoplastic polymers made from renewable sources. PLA is generally produced by ring opening polymerization (ROP) of lactide using the metallic/bimetallic catalyst (Sn, Zn, and Al) or other organic catalysts in a suitable solvent. In this work, reactive extrusion experiments using stannous octoate Sn(Oct) 2 and tri-phenyl phosphine (PPh) 3 were considered to perform ROP of lactide. Ultrasound energy source was used for activating and/or boosting the polymerization as an alternative energy (AE) source. Ludovic ® software, designed for simulation of the extrusion process, had to be modified in order to simulate the reactive extrusion of lactide and for the application of an AE source in an extruder. A mathematical model for the ROP of lactide reaction was developed to estimate the kinetics of the polymerization process. The isothermal curves generated through this model were then used by Ludovic software to simulate the "reactive" extrusion process of ROP of lactide. Results from the experiments and simulations were compared to validate the simulation methodology. It was observed that the application of an AE source boosts the polymerization of lactide monomers. However, it was also observed that the predicted residence time was shorter than the experimental one. There is potentially a case for reducing the residence time distribution (RTD) in Ludovic ® due to the 'liquid' monomer flow in the extruder. Although this change in parameters resulted in validation of the simulation, it was concluded that further research is needed to validate this assumption.