Magister Chirurgiae Dentium - MChD (Prosthodontics) / The aim of this study was to evaluate and compare the physical properties of two core build-up materials (ParaCore and CoreXflow) and compare this to conventional composite material (Filtek Supreme Plus and SDR Flow) used as core build-up material.

Sammanfattning Syfte och frågeställningar. Syftet med denna studie var att på äldre personer studera olika fysiologiska parametrar före och efter en period på åtta veckor med styrketräning som utförs tre gånger i veckan. Frågeställningarna var: Hur påverkas statisk och dynamisk maximal styrka i främre lårmuskulaturen av styrketräning? Är det någon skillnad i resultat mellan koncentrisk och excentrisk styrka i lårmuskulaturen före och efter styrketräningsperioden? Är det någon skillnad i förändring mellan benstyrka uppmätt med isokinetisk teknik jämfört med uthållighetsstyrka och ett kort funktionellt benstyrketest? Hur påverkas maximal syreupptagningsförmåga registrerad via submaximalt cykeltest respektive vid pyramidtestet av träningsperioden? Metod. I studien deltog 20 generellt ej påtagligt aktiva män och kvinnor i åldrarna 66-79 år. Av dessa var 11 individer slumpvis indelade i en styrketräningsgrupp och övriga nio utgjorde en inaktiv kontrollgrupp. Ett flertal olika fysiologiska tester, som bl.a. prövade testpersonernas styrka samt kondition, utfördes innan och efter träningsperioden. De deltagare som utgjorde träningsgruppen tränades i relativt tung styrketräning i åtta veckor. Resultat. Undersökningen resulterade i en signifikant ökad koncentrisk-, excentrisk- samt statisk momentan benstyrka för träningsgruppen efter de åtta veckorna med relativt tung styrketräning. Vidare kunde även utläsas för dem en signifikant förbättring av uthållighetsstyrka i benen (hastighet vid 50 uppresningar från stol, med 16,9 %) samt vid ett kort funktionellt test (5 uppresningar från stol, med 12,8 %). De träningsgenererade signifikanta ökningarna för träningsgruppen tyder inte på några stora procentuella skillnader mellan statisk (10,4 %) och dynamisk excentrisk (7,8 %) eller koncentrisk maximal styrka (9,5 %). Vid testerna cykelergometertest (kondition), effekt i 5-minuterspyramidtest (ett modifierat steptest) samt distans vid 6-minuters gångtest framkom inga signifikanta förbättringar för träningsgruppen. Ingen i kontrollgruppen visade en signifikant förbättring i någon av de nämnda testerna. Slutsats. Studien visar att interventioner, med åtta veckors intensiv styrketräning, tre gånger per vecka för äldre kvinnor och män, påtagligt kan förbättra resultaten vid styrkemätningar såväl momentant som uthållighetsmässigt och vid ett kort funktionellt test, medan tester av maximal syreupptagningsförmåga (VO2max) inte förbättras. Emellertid framkom i cykelergometertestet en tendens till förbättring för träningsgruppen.

Ergonomics software programs often use an independent axis approach (IAA) to calculate resultant shoulder strength to predict manual arm strength (MAS). The IAA treats strength about each joint axis (joint axis strengths: JAS) in the arm as independent motors, which all combine to complete an exertion. However, this form of modeling is not a true physiological representation of how the shoulder/arm function. The weighted average approach (WAA) was proposed, which combines the axes by weighting each strength based on its relative contribution to the resultant moment vector. The primary purpose of this thesis was to test the IAA using participant-specific JAS values, such that it afforded the IAA the best opportunity to predict MAS accurately. The secondary purpose was to test the WAA, to determine if it was a viable replacement for the IAA. Fifteen university age females completed two data collections. One tested the eight different JASs for the shoulder and elbow, and the other tested participant’s MASs in four hand locations and six exertion directions. The JAS force data, and postural kinematic data (from the MAS collection), were inputs into two models, which completed the MAS predictions. A 4 x 6 x 3 repeated measures ANOVA revealed a significant three-way interaction between hand location, exertion direction, and method of MAS estimation (p<0.0001) on MAS. The most important finding of the thesis was that both the IAA and WAA predictions were significantly different than the MAS values. The IAA and WAA explained only 17.9% & 19.1% of the variance with RMS errors of 74.5 N & 73.4 N, respectively. This indicated that ergonomics software programs, using the IAA, should not be used to make arm strength predictions by ergonomists, and that WAA was not a viable replacement for the IAA. / Thesis / Master of Science in Kinesiology

This review discusses previous literature that has examined the influence of muscular strength on various factors associated with athletic performance and the benefits of achieving greater muscular strength. Greater muscular strength is strongly associated with improved force-time characteristics that contribute to an athlete’s overall performance. Much research supports the notion that greater muscular strength can enhance the ability to perform general sport skills such as jumping, sprinting, and change of direction tasks. Further research indicates that stronger athletes produce superior performances during sport specific tasks. Greater muscular strength allows an individual to potentiate earlier and to a greater extent, but also decreases the risk of injury. Sport scientists and practitioners may monitor an individual’s strength characteristics using isometric, dynamic, and reactive strength tests and variables. Relative strength may be classified into strength deficit, strength association, or strength reserve phases. The phase an individual falls into may directly affect their level of performance or training emphasis. Based on the extant literature, it appears that there may be no substitute for greater muscular strength when it comes to improving an individual’s performance across a wide range of both general and sport specific skills while simultaneously reducing their risk of injury when performing these skills. Therefore, sport scientists and practitioners should implement long-term training strategies that promote the greatest muscular strength within the required context of each sport/event. Future research should examine how force-time characteristics, general and specific sport skills, potentiation ability, and injury rates change as individuals transition from certain standards or the suggested phases of strength to another.

[Truncated abstract] Resistance training is increasingly popular for improving strength qualities such as hypertrophy, maximal strength, endurance and power. Although many resistancetraining programmes now adhere to the concept of periodisation, the number of studies examining its structure and design are few, and there are just a handful of studies that have examined periodised training for the maintenance of strength and power. Even rarer, are periodised resistance-training studies that utilise female subjects. Previous studies have compared non-periodised training regimens such as Progressive Resistance Exercise (PRE), and the two main models of periodisation, Linear Periodisation (LP) and Undulating Periodisation (UP). Results are inconclusive as to whether the efficacy of the periodised training programmes were due to the manipulation of training variables such as volume and intensity, or that training programmes with higher doses of volume induced better training responses. However, to make effective comparisons between training programmes, the training volume or workload (total load lifted x total repetitions) and training intensity have to be equated between the groups under examination. While the intensities (percentage of one-repetition maximum, 1 RM) for improving strength qualities such as hypertrophy and maximal strength have general consensus among resistance-training practitioners, there exists disagreement over the intensity that should be used during the training of power. Thus, it is important to first identify the load for power training before comparisons can be made between LP and UP programmes using equal training volumes. ... The final study found that adhering to two UP maintenance training programmes with equalised volumes and intensities twice a week increased upper-body strength and maintained lower-body strength adequately across a 3-wk phase. The results from these studies support previous results that suggest training programmes with higher workloads and repetitions produce superior strength and power adaptations, and it is not specifically the variation of training volume and intensity within a periodised programme that improves strength qualities. Thus, both periodised programmes used in this thesis can be recommended for untrained and moderatelytrained women as both LP and UP were found to be similarly effective for increasing upper- and lower-body hypertrophy, strength and power.

Interlocking Cross Laminated Timber (ICLT) wall panels are a new wood construction product similar to Cross Laminated Timber panels. Besides being an innovative structural system, they also utilize beetle killed timber from many of the forests that have been devastated by the Mountain Pine Beetle. Three tests were performed on three ply ICLT panels measuring 8 feet (2.44m) wide, 8 feet (2.44m) tall and 8.5 inches (21.6cm) thick to determine the racking, flexural and axial strengths of the wall panels. After each test was performed the walls were disassembled and investigated for cause of failure. Using the data from the tests as a benchmark, simple analytical models to predict the design capacities of the walls for racking, flexural, and axial strengths were established. The analytical models for racking strength, flexural strength and axial strength predicted reasonably well the measured strength values. Additional testing is necessary to increase the available database, further validate the analytical models developed, better understand the structural performance of ICLT panels, and establish acceptable design methodology for ICLT wall panels.

Call number: LD2668 .T4 1964 J58 / Master of Science

Unique features of behavior of granular materials make constitutive modeling of these materials a challenge that has not yet been answered completely. Because volume changes are so important for the type of behavior exhibited by frictional materials, it is important to correctly incorporate them in constitutive models, both in terms of their rate of development and their magnitude. In this study a number of consolidated drained triaxial tests are performed to find those features of sand behavior that can be considered "material parameters" and can be used for constitutive modeling of granular soils. Special attention is given to those features of material behavior that are related to dilatancy. A number of published experimental data are also analyzed and useful trends of soil behavior are found.

Thesis (M.Tech.: Chiropractic)--Durban University of Technology, 2008 / The core stability, club head velocity and ball carry in golfers with and without low back pain – a comparative study. Objective: The aims of this study was to establish whether an observable difference exists in the abdominal core stability of two comparable groups of golfers: one asymptomatic and the other suffering from low back pain, and whether an observable reduction of performance, expressed as club head velocity and ball carry can be observed in those with low back pain. First Objective was to differentiate the groups at baseline with respect to core stability strength between asymptomatic golfers and golfers suffering from low back pain. Whereas the Second Objective was to establish whether a relationship exists between abdominal core stability, CHV and ball carry in the two population groups under study. Following the above the Third Objective was to establish which other factors besides core stability strength have an effect on CHV and ball carry. And lastly the Fourth Objective was to establish the correlation between CHV and ball carry. Design: A comparative study was carried out between the two sample groups. A sample of forty patients were selected for this study, where twenty patients were asymptomatic and had no current episode of low back pain and were able to maintain a core contraction; and the other twenty patients low back pain and could not maintain a core contraction. Because the patients presented in a random manner, the patients were matched as close as possible according to age, so as to have better comparative value between the groups (the maximum age difference of a year was instituted). This allowed for comparisons among similar ages, with the difference being their low back pain and core contraction status. Outcome Measure: Each golfer was required to hit 5 balls using a standard club (in this study, a standard driver was used), after which an average value v was calculated for CHV and ball carry. All measurements were carried out using the Flightscope Pro machine at the Durban Pro Shop. Results: Core stability and low back pain did not influence CHV. However there was a non significant trend which indicated higher ball carry in the group with better core stability and no low back pain than in the group with low back pain and poor core stability. Increasing age and handicap reduced the CHV and ball carry values significantly. Ball carry and CHV were positively correlated together in both groups.

In this thesis, I investigated effects of conflict strength and ageing on cognitive control. Conflict strength was manipulated in the Eriksen flanker task using two different approaches: 1. independent variation of flanker and target contrast; 2. manipulation of stimulus onset asynchrony (SOA). Reducing flanker contrast relative to target contrast decreased conflict strength, as shown by a reduction in compatibility effects, when contrast conditions were presented in a randomized fashion but not when they were presented block-wise. An SOA of 100 ms did lead to increased compatibility effects compared to SOAs of 0 ms and 200 ms. Effects of conflict appear to be reflected in the N2 component of the ERP. Although priming played a crucial role in the emergence of the sequential adjustment effect, conflict strength also influenced this effect to a certain degree, supporting the claim that sequential adjustments represent an adaptation of cognitive control. Post-error slowing and error-related ERP components, on the other hand, were not affected by the conflict manipulations, suggesting that errors cannot be explained in terms of conflict processing. Effects of ageing on cognitive control were investigated in a group of middle-aged participants. Although physiological indicators of conflict and error processing were compromised in this age group and overall response times were increased, compatibility, sequential adjustment, and post-error slowing effects were of comparable size as in young adults. These findings suggest that participants could successfully compensate for age-related physiological changes at this early stage of ageing. In conclusion, the research presented in this thesis provided important information to extend our knowledge of factors influencing cognitive control processes.