Background: Rugby injuries are a common phenomenon. The aim of medical professionals is to treat these injuries to the best of their abilities, and if possible, to help prevent their occurrence. Bahr and Holme (2003) argue that sports participation carries with it a risk of injury, with the even more weighty issue that it might later even lead to physical disability. Junge, Cheung, Edwards and Dvorak (2004) recommends the development and implementation of preventative interventions to reduce the rate and severity of injuries in Rugby Union. The Medical and Risk Management Committee of USA Rugby (2003) also reports that the key to preventing injuries in any sport is identifying and addressing the risk factor associated with it. Various studies have identified weakness in plyometric strength, proprioception arid balance as - of lower leg and ankle injuries (Margison, Rowlands, Gleeson arid Eston, 2005; Stasiwpoulos, 2004; Verhagen, Van der Beck, Twisk, Bahr and Mechelen, 2004; Baltaci & Kohl, 2003; Mlophy, Conaoly and Beynnon, 2003; Moss, 2002; Anderson). Aims: ThE aim of this study was to investigate the influence of proprioception, balance and plyometric strength on the occurrence of lower leg injuries in schoolboy rugby players. A further aim was to develop a preventative training programme to address these variables, should they prove to have an influence on lower leg injuries. The possible inclusion of these tests in talent identification test batteries will also be examined. Design: A prospective cohort study. Subjects: A group of 240 schoolboys in U/14, U/15, U/16 and U/18 age groups in two schools (Hoër Volkskool Potchefstroom ("Volkskool") and Potchefstroom Boys High School ("Boys High")) in the North West Province of South Africa was used as the test cohort. Method: At the beginning of the 2006 rugby season all players were tested for proprioception, balance and plyometric strength. These tests were conducted using a computerised tilt board for proprioceptive testing; Star Excursion Balance Test for Balance and an electronic timing mat for plyometric strength. During the season, weekly injury clinics were held at both schools to document all injuries that occurred following the preceding weekend's matches. A statistical analysis was done on all the data collected from the test batteries and injury clinics. Descriptive statistics (means, standard deviation, minimum and maximum) were used as well as practical significant differences (d-values) (Cohen, 1988). The ratios for left and right leg plyometric strength to bilateral plyometric strength (L+R/Bil) and individual left and right leg plyometric strength to bilateral plyometric strength (L/Bil and R/Bil) were also calculated. Results: A profile of proprioception, balance and plyometric strength was compiled for schoolboy rugby players using the test data The U/18 players generally bad the best test results of all the age groups, outperforming U/14, U/15 and U/16 players with most tests. U/15 players outperformed both U/14 and U/16 players. Backline players performed better than loose forwards and forwards in plyometric tests in most age groups. Loose-forwards also outperformed tight-forwards with plyometrics at most age groups. At U/15 and U/16 level, tight-forwards slightly outperformed loose-forwards with Star Excursion Balance Tests. Generally, A-teams performed better than B-teams with all the tests except L+R/Bil; L/Bil and R/BiI. The difference between the teams, however, only had a small to medium effect and cannot be considered practically significant. At U/14 and U/15 levels, there were more practically significant differences between the A- and B-teams, with A-teams outperforming B-teams. The tests could have some value for talent identification at this age level. A rugby epidemiological study was done on the data collected in the weekly injury clinics. This study recorded 54 injuries at the two schools involved during the 2006 season from April to July. Two hundred and forty players were involved in 10890 hours of play. Eight thousand nine hundred and ten of these player hours were practices and 1980 were match hours. These injuries occurred at a prevalence rate of 4.96/1000 player hours. Match injuries accounted for 77.78% of all injuries with training sessions resulting in the remaining 22.22% of injuries, with a match injury rate of 1 injury per individual player every 3.14 matches. U/14 players showed an overall match injury rate of 11.11/1000 match hours. U/15 players showed a rate of 2.47/1000 match hours. The low rate may be attributed to underreporting of injuries by the U/15 players. U/16 players showed a late of 22.33/1000 hours, while U/18 players showed an exceptionally high rate of 45/1000 match hours. The tackle situation was responsible for the highest percentage of injuries (57.14%). Boys High presented with more injuries (57.4%) than Volkskool at a higher prevalence rate (5.60/1000 player hours). In a positional group comparison, backline players presented with 51.85% of injuries. Since backline players only present 46.7% of players in a team, this shows that backline players have a higher risk of injury. A-team players presented with 66.6% of injuries at a prevalence rate of 6.37/1000 player hours. B-team players had an injury rate of 3.43/1000 player hours. The test values for the players suffering lower leg injuries were compared to those for uninjured players. There were eight players with nine lower leg injuries: one player had injuries of both legs. Six of the injuries were intrinsic of nature and two players had extrinsic injuries. Test values for all five tested players with intrinsic injuries were weaker by a high practically significant margin for the L+R/Bil ratio. Conclusion: L+R/Bil proved to be the test result with the most influence on the occurrence of intrinsic lower leg injuries. When the individual test results for the players with intrinsic injuries are compared to the percentiles for all players, it becomes visible that the injured players fall in the 20th percentile for both L+R/Bil and Injured leg/Bil ratios. These 20th percentile values could thus be used as a standard for determining the possible occurrence of intrinsic lower leg injuries. These 20th percentile values are 1.012 for R+L/Bil ratios; 0.483 for L/Bil ratios and 0.492 for R/Bil ratios. This study shows that plyometric ratios for L+R/Bii, L/Bil and R/Bil have an influence on lower leg injuries in schoolboy rugby players. Proprioception and balance did not have any practically significant effects on the occurrence of these injuries. A preventative training programme was also designed following a study of the literature, combined with these results. The tests could also possibly be integrated in talent identification test batteries at U/14 and U/15 level. / Thesis (M.Ed.)--North-West University, Potchefstroom Campus, 2007

In this study we explored some of the factors associated with biased processing of attitude-relevant information. We were particularly interested in the possibility that a self-affirmation, by reducing self-evaluative concerns, might increase participants' willingness to impartially evaluate information that conflicts with their current views. We examined students' reactions to arguments about increasing tuition as a function of four factors: attitude importance, argument strength, the congruence of arguments with existing attitudes, and our experimental manipulation of affirmation. We found that affirmation reduced biased evaluation only for participants who rated the issue as important. We also found that affirmation dramatically impacted the perception of argument strength. Stronger counterattitudinal arguments were rejected by non-affirmed participants, who did not distinguish them from weak arguments, presumably because of the esteem threat posed by a strong ideological challenge. Affirmed participants, though, evaluated strong counterattitudinal arguments more positively.

This thesis is concerned with the study of different effects in protein ultrafiltration including device configuration, solution chemistry and membrane charge In the recent and more established literature membrane fouling remains a challenging problem that limits the wider application of ultrafiltration. Thus, investigations which can aid understanding and potentially reduce membrane fouling are of particular interest and in this study the problem has been addressed from several different angles Polyethersulfone membranes were studied at varying pH and two ionic strengths using bovine serum albumm and lysozyme as the model proteins. The study was conducted both in a stirred cell and a crossflow configuration in order to evaluate the influence of different system hydrodynamics on filtration This work was further substantiated through the application of filtration models An attempt was also made to modify the membrane surface by low temperature plasma modification with the intention to preferentially alter the characteristics of the membrane surface Both unmodified and plasma-modified polyethersulfone membranes were characterised using a range of analytical methods including flux data, streaming potential, contact angle and MWCO measurements to aid results interpretation. The research showed that MWCO data quoted by manufacturers is mostly greater than that obtained during laboratory studies The MWCO technique was also used to highlight differences between the unmodified and plasma-modified membranes demonstrating that the modification resulted in a membrane with tighter pores in the lower molecular weight region. Concentration polarisation effects were found to be reduced as a result of the plasmamodification The study of protein filtration at different pH and ionic strengths demonstrated that ionic strength effects were more pronounced than pH effects It was also shown that changes m the ionic strength can be used to alter the degree of protein rejection for the given system concentration polarisation was found to be higher during crossflow filtration compared to stirred cell filtration The thesis adds to existing knowledge in the area of ultrafiltration emphasizing the importance of device configuration, solution chemistry as well as the potential of charged membranes

Concrete filled steel hollow structural (CFS) sections are increasingly used to support large compressive loads in buildings, with the concrete infill and the steel tube working together to yield several benefits both at ambient temperature and during a fire. These members are now widely applied in the design of highly optimized multi-storey and high rise buildings where fire resistance ratings of two or more hours may be required. Whilst the response and design of these sections at ambient temperatures is reasonably well understood, their response in fire, and thus their fire resistance design, is less well established. Structural fire resistance design guidance is available but has been developed based on tests of predominantly short, concentrically-loaded, small-diameter columns in braced frames using normal strength concrete. The current prescriptive guidance is limited and the design of CFS columns is thus often based on a detailed performance based approach, which can be time consuming and expensive and which is generally not well supported by a deep understanding of CFS columns’ behaviour in real fires. This thesis aims to understand the fundamental thermal and mechanical factors at play within these sections so as to provide guidance on how to improve their design for fire resistance when applied either as unprotected or protected sections. A meta-analysis of available furnace test data is used to demonstrate that current guidance fails to capture the relevant mechanics and thus poorly predicts fire resistance. It is also demonstrated that the predictive abilities of the available design standards vary with physical characteristics of the CFS section such as shape and size. A factor which has been observed in furnace tests on CFS sections but which is not accounted for in available guidance is the formation of an air gap between the steel tube and the concrete core due to differential expansion; this affects their structural response in fire. The insulating effect of air gap formation has not previously been addressed in literature and an experimental program is presented to systematically assess the effects of a gap on the heat transfer through the section; showing that the presence of even a 1 mm gap is important. To explicitly assess the heat transfer response within both unprotected and fire protected (i.e. insulated) CFS sections, 34 large scale standard furnace tests were performed in partnership with an industry sponsor. Fourteen tests on large scale unloaded unprotected CFS sections are presented to assess current capability to predict the thermal response and to assess the effects of different sectional and material parameters on heating. New best practice thermal modelling guidance is suggested based on comparison between the models and observed temperatures from the tests. Twenty CFS specimens of varying size and shape, protected with different types and thicknesses of intumescent paint fire insulation, were also tested unloaded in a furnace to understand the thermal evolution within protected CFS sections and to develop design guidance to support application of intumescent coatings in performance based fire resistance design of CFS sections. These tests demonstrate that the intumescent coatings were far more effective than expected when applied to CFS sections, and that current methods of designing the coatings’ thickness are overly conservative. The reason for this appears to be that the calculation of effective section factor which is used in the prescription of intumescent coating thicknesses is based on the thermal response of unprotected CFS sections which display fundamentally different heating characteristics from protected sections due to the development of a thermal gradient in the concrete core. It is also demonstrated (by calculation supported by the testing presented herein) that the steel failure temperature (i.e. limiting temperature) of an unprotected CFS column in fire is significantly higher than one which is protected; procedures to determine the limiting temperature of protected sections are suggested. Finally, the residual strength of fire-exposed CFS columns is examined through structural testing of 19 of the 34 fire tested columns along with unheated control specimens. The results provide insights into the residual response of unprotected and protected CFS section exposed to fire, and demonstrate a reasonable ability to calculate their residual structural capacity. The work presented in this thesis has shed light on the ability of available guidance to rationally predict the thermal and structural response to fire of CFS columns, has improved the understanding of the thermal evolution within protected and unprotected CFS sections in fire, has provided best-practice guidance and material input parameters for both thermal and structural modelling of CFS sections, and has improved understanding of the residual capacity of CFS sections after a fire.

The purpose was to examine actual force (AF) productions of males for accuracy during leg extensions when given a random desired force (DF) ranging from 10-90% of maximal force (MF). Thirty males ranging from 18 to 30 years of age (M = 21.99 + 3.04), who had no previous experience with the test equipment, went through 9 randomly ordered submaximal efforts followed by a maximal effort. Correlations between AF and DF were high (r > .79) and test-retest was consistent between AF (r = .87) and MF (r = .90). Participants consistently undershot DF on both test and retest from 20-90% and overshot DF only at 10%. Power functions revealed exponents of less than 1, indicating that AF grows slower then DF for both test .70 (.95 CI = .63 - .77) and retest .66 (.95 CI = .60 - .73). The results replicate a prior study by Jackson, Martin, Koziris, Ludtke, and Dishman (2001) that used incremental rather than random increases in DF.

The purpose of this study was to investigate strength and flexibility development as each is affected by three training programs using two apparatuss the Exer-Genie and the Super-Mini-Gym.

Two different weight training programs were compared to determine which was most effective in improving strength. The experiment was conducted with the bench press, leg press, and sitting press for a period of fifteen weeks.

The purpose of this study was to determine the effects of weight loadings and repetitions, frequency of exercise, and knowledge of theoretical principles of weight training on changes in muscular strength. Another purpose was to analyze these effects and determine implications for coaches, physical educators, physical therapists, and others interested in determining the optimum combination of the three variables for increasing muscular strength.

Many chemical and physical factors govern the mobility of metal contaminants in soils and clay systems; some of these chemical factors include mineralogical composition, cation exchange capacity, organic matter content, pH and the ionic strength of soil water. This makes understanding and therefore predicting the fate of metal contaminants in soils a complex undertaking. There were two broad objectives in this study. The first was to investigate binary and ternary sorption systems, with the aim to understand the effects that factors such as pH, ionic strength, organic matter and metal concentrations, have on sorption of simple clay minerals (bentonite and kaolinite) with metals (cadmium, caesium, nickel and strontium). The second was to investigate the retention of heavy metals and radionuclides by well characterised organic-rich and organic-poor clay soils, breaking them down to their individual components to help understand the effects of each component separately, the study also tested to see if the additivity principle holds for these heavy metals and radionuclides, the additivity principle presumes that the overall sorption behaviour of a complex mixture is a summation of the weighted individual sorption behaviours of its constituents. The study also determined the relationship between the natural organic matter (NOM) content and cation exchange capacity (CEC) of the soils and how these affect the mobility of the metals, while also considering the relative importance of the speciation of the metals. Two British clay soils (Mercia Mudstone and London Clay) and two Nigerian soils (an organic-rich Ikeja Loam and the other organic-poor Magodo Laterite) were characterised by X-ray diffraction (XRD) analysis. Batch techniques were employed for the sorption studies, and radiometric techniques, ICP-OES and ICP-MS were used to quantify metal distribution between phases. The sorption of dissolved organic matter to clay minerals is very dependent on pH; this dependence is greater with increasing concentration of organic matter. The formation of metal-humate complexes is dependent on the nature of the metal and pH. Caesium exhibits no discernible sorption to humic acid, cadmium sorption is enhanced by increasing alkalinity but this enhancement is slightly reduced in higher concentrations of humic acid, nickel sorption is mostly unaffected by pH except in higher concentrations of humic acid and enhanced only under very low concentrations of humic acid, while strontium sorption to humic acid is reduced with increasing alkalinity. The nature and preference of humic acid sorption for these metals are vital to understanding the role played by humic acid in the ternary sorption studies of metals, humic acid and clay minerals. Strongly acidic conditions dominate other factors affecting sorption such as ionic strength in sorption of metals to clay minerals. Caesium sorption to bentonite at pH 4 is poor and almost unaffected by ionic strength of the electrolyte solution; saturation of sorption sites is reached with low amounts of adsorbed caesium. Strontium also binds poorly to bentonite at pH 4, more so than caesium, but an ionic strength effect on sorption still exists and is discernible even under these conditions. Increasing alkalinity has the expected effect of increasing sorption capacity of bentonite for both metals. Bentonite has poor sorption properties, having low affinity for caesium and strontium, but has greater affinity for caesium than strontium. The presence of humic acid can enhance or suppresses sorption, this varies from metal to metal and from solid to solid, the degree of enhancement or suppression also depends on humic acid concentration. Kaolinite has better sorption properties than bentonie. Cadmium has greater sorption affinity for kaolinite in the absence of humic acid, but nickel sorption is more enhanced in the presence of humic acid. Although the presence of humic acid enhances cadmium and nickel sorption to kaolinite, low humic acid concentration provides the best conditions for maximum sorption of both metals. High concentrations of humic acid lead to colloid formation which block access of metals with larger hydration radii to sorption sites while also encouraging the formation of humic acid-metal complexes. As with bentonite, caesium and strontium are both poorly sorbed by kaolinite. Unlike with cadmium and nickel however, the enhancement of strontium sorption is supported by higher concentrations of humic acid, these confirm a greater preference for the formation of S-HA-Sr ternary and lower preference for the formation HA-Sr binary complexes. The presence of humic acid inhibits caesium binding, and retention but this reduces with increasing alkalinity, while the reverse is the case with strontium whose retention is very poor and improved in the presence of humic acid and increasing alkalinity. Both caesium and strontium are poorly sorbed and retained by kaolinite but their retention improves with increasing humic acid concentration and pH. Cadmium and nickel also exhibit poor retention to kaolinite but their retentions are more improved under alkaline conditions and higher humic acid concentrations, nickel more so than cadmium. Similar sorption affinities were exhibited by the British (London Clay and Mercia Mudstone) and Nigerian soils (Magodo Laterite and Ikeja Loam) for the metals studied, showing the significance of soil constituent contribution to sorption behaviour. Both British clay matrices have affinity for the metals in the order Cs >> Cd ≈ Ni >> Sr, London Clay has the greater sorption capacity for all the metals, the clay mineral content of Mercia Mudstone is almost entirely made up of Illite while London Clay contains a mixture of smectite, illite and kaolinite with smectite being the most prevalent clay mineral phase. These confirm that smectite-rich clay systems will exhibit better sorption and retention capacities for metal contaminants. Both Nigerian soils showed the same order of affinity for all the metals Cd >> Ni >> Cs >> Sr, cadmium s preferential sorption to kaolinite was observed in its greater sorption and retention by the Nigerian soils which are kaolinite-rich. This preferential sorption of cadmium by kaolinite is confirmed by the Standard Addition experiment where its contribution to cadmium sorption is clearly evident, a trend not replicated with nickel as the sorbing metal. The presence of organic matter in soils or clay systems improves their metal sorption capacity significantly, especially true for insoluble organic matter, however its significance is reduced as pH increases. The contribution of organic matter also depends on the sorption affinity of the metal for organic matter; metals such like strontium are more affected by organic matter presence. The overall sorption behaviour of complex systems such as soils is difficult to attribute to their individual constituents. The laterite soils can be considered a relatively simple soil system containing only four constituents in significant quantities, yet it is difficult to replicate its sorption behaviour using a replicate proportioned mixture of its constituent phases. The additively calculated sorption profiles for the synthetic laterite were different from those obtained experimentally, the reason for this is that the existence of significant particle size differences between the natural and synthetic soils give rise to differences in the availability of sorption sites which is evident from the different CEC values measured for both systems.

Enamel decalcification caused by poor oral hygiene is a significant problem in orthodontics. Bioactive glass-containing resins have been shown to release Ca2+ ions into surrounding solution. The purpose of this study was to determine the shear bond strength of four different compositions of orthodontic resin prepared with bioactive glass (N=20). Premolars were bonded using one of four BAG-BOND compositions. Brackets were debonded and ARI scores were given. The mean shear bond strength was 7.23 ± 2.47 MPa (62 BAG-BOND), 8.25 ± 2.87 MPa (65 BAG-BOND), 8.78 ± 3.08 MPa (81BAG-BOND) and 5.80 ± 2.27 MPa (85 BAG-BOND). 65 and 81 BAG-BOND were significantly higher than 85 BAG-BOND. The 62 BAG-BOND group was not statistically significantly different from any other group. All groups exhibited a cohesive bond failure and were not statistically significant from each other. Three compositions of the novel orthodontic adhesive exhibited adequate bond strength for clinical applications.