Simulation models based on the elliptic mild or steep slope wave equation are frequently used to estimate wave properties needed for the engineering calculations of harbors. To increase the practical applicability of such models, a method is developed to include the effects of rubble mound structures that may be present along the sides of entrance channels into harbors. The results of this method are found to match those of other mathematical models (i.e. parabolic approximation & three-dimensional solution) under appropriate conditions, but they also deviate from results of parabolic approximations in some cases because dissipation can create angular scattering. Comparison with hydraulic model data also shows that this approach is useful for designing pocket wave absorbers that are used to reduce wave heights in entrance channels.

Natural graphite from cheap and abundant natural sources is an attractive anode material for lithium ion batteries. We report on modifications of such a common natural graphite, whose electrochemical performance is very poor, with solutions of (NH4)2S2O8, concentrated nitric acid, and green chemical solutions such of e.g. hydrogen peroxide and ceric sulfate. These treatments resulted in markedly im-proved electrochemical performance (reversible capacity, coulombic efficiency in the first cycle and cycling behavior). This is attributed to the effective removal of active defects, formation of a new dense surface film consisting of oxides, improvement of the graphite stability, and introduction of more nanochannels/micropores. These changes inhibit the decomposition of electrolyte solution, pre-vent the movement of graphene planes along a-axis direction, and provide more passage and storage sites for lithium. The methods are mild, and the uniformity of the product can be well controlled. Pilot experiments show promising results for their application in industry.

Children with mild disabilities are known to have difficulties with developing mathematical skills (Hoard, Geary, & Hamson, 1999). Yet, children with mild intellectual disabilities (MIDs) have rarely been included in rigorous scientific research. The present study has three goals. The first goal was to determine the structure of mathematics achievement in elementary aged children with MIDs and children with reading disabilities (RDs) without accompanying mathematics disabilities. The second goal was to establish the measurement stability of mathematics achievement. The third goal was to evaluate students’ response to a mathematics intervention. The participants were 265 children with MIDs and 137 children with RDs. Confirmatory factor analysis and measurement invariance evaluation was utilized to determine the structure of mathematics achievement and to ensure reliable and valid measurement of mathematics achievement between groups across three time points. The results of measurement invariance evaluation indicated that a joint model specification, characterized by two groups, both of which included children with MIDs and children with RDs who were differentiated according to intervention condition participation (not disability status), provided the best account of the underlying data structure. Further, the structure of mathematics achievement in the present sample was unidimensional, and the measurement of mathematics achievement was temporally stable between groups. Finally, latent mathematics achievement growth was evaluated. The results indicated that students in the mathematics intervention condition evidenced an advantage over those in a reading intervention condition at mid- and post-intervention evaluation, while also evidencing more growth in this conceptual domain. Instructional implications are discussed in terms of topic choice and pacing.

Mild cognitive impairment (MCI) has long been associated with depression; however, few studies have addressed the presence of (prolonged) intrapersonal grief or its contribution to emotional distress in MCI. This may be a result of both an over-reliance on interpersonal models of grief (i.e. bereavement) and a systematic undervaluing of MCI individuals’ perspectives. Thus, this study took a qualitative approach, using interpretive description, to understand the first-hand experience of persons with MCI, with the intent of 1) determining whether grief occurs for this group and, if so, 2) comparing this experience to well-defined grief constructs. Six themes were identified: Uncertainty and ambiguity, losses of self and role, disenfranchisement and disconnection, primacy of MCI, emotional distress, and coping. A relationship between themes was found, such that uncertainty and ambiguity, losses of self and role, and disenfranchisement and disconnection comprised the core dimensions of the MCI experience, with losses of self and role serving a central and binding role between the other two. These core dimensions then contributed individually and collectively to the primacy of the MCI experience and emotional distress, which in turn exhibited a reciprocal relationship with coping. The overall experience of MCI reflects features of several grief reactions to nonfinite loss, most notably chronic sorrow and disenfranchised grief. Implications for practice and further investigation are discussed. / Graduate

M. Tech. Chemical Engineering. / Discusses the effect of ferrous gluconate (FG) and zinc gluconate (ZG) as novel corrosion inhibitors on the corrosion rate of mild steel and aluminium alloy in 3.5% NaCl and 0.5 M H2SO4 media was investigated by electrochemical and weight loss techniques. The effect of inhibitor concentration was investigated. The concentration of these inhibitor ranges from 0.5 to 2.0% g/v at a temperature of 28OC. The synergetic effect of these inhibitors was also studied. High resolution scanning electron microscopy equipped with energy dispersive spectroscopy (HR-SEM/EDS) and Raman spectroscopy was used to characterize the surface morphology of the metals before and after corrosion. Experimental results revealed that ferrous gluconate and zinc gluconate in 3.5% NaCl and 0.5 M H2SO4 solution decreased the corrosion rate at the different concentrations studied. Maximum inhibition efficiency of 100% was achieved for mild steel at 0.5% g/v concentration of FG, 0.5% g/v concentration of ZG and 1.5% g/v synergetic of FG + ZG in 3.5% NaCl solution. Similarly, 100% inhibition efficiency was obtained for aluminium alloy at different media studied (3.5% NaCl and 0.5 M H2SO4). The experimental results obtained from potentiodynamic polarization method showed that the presence of FG and ZG in 3.5% NaCl and 0.5 M H2SO4 solutions decreases the corrosion current densities (icorr) and corrosion rates (CR), and increases the polarization resistance (Rp). It was observed that the inhibitor efficiency depends on the corrosive media, concentration of the inhibitor and the substrate material. The adsorption characteristics of FG and ZG were best described by the Langmuir and Freundlich isotherms. Good correlation exists between the results obtained from both polarization and weight loss methods.

M. Tech. Engineering Metallurgy. / Aims to improve the mechanical and chemical properties of mild steel, by developing highly corrosion resistant surface coatings of zinc-aluminum using the electro-deposition techniques. Properties that are targeted are specifically hardness, wear and corrosion resistances.

Denna studie bygger på empiri från två genomförda fokusgrupper med syftet att undersöka hur elever med lindrig utvecklingsstörning på gymnasiesärskolan upplever termen särskola. Den teoretiska referensram som använts är ett socialkonstruktionistiskt perspektiv med sär-skild fördjupning på teorier om kategorisering. Studiens resultat analyserades genom tematisk innehållsanalys och resultatet visade att samtliga elever som deltog i fokusgrupperna upplevde termen särskola negativ och att de önskade att termen togs bort. Termen särskola bidrog till tankar och känslor av att vara mindre värd och att vara avvikande. De nackdelar eleverna lyfte med termen och skolformen var att det bidrar till begränsningar, mobbing och stämpling. Ena fokusgruppen upplevde att skolformen som sådan är positiv, medan den andra fokusgruppen upplevde att den är negativ. I båda fokusgrupperna lyftes att vilken annan term som helst vore bättre än termen särskola, men att det inte borde finnas en särskilt term överhuvudtaget. I ena fokusgruppen lyftes oro kring att en förändrad term inte skulle göra någon skillnad. Studiens slutsatser är att terminologin och samhällets attityder bör förändras. Särskild vikt bör läggas vid att informera professionella, som har kontakt med elever på särskolan, om elevernas upp-levelser av termen. Vidare bör termen särskola studeras ytterligare, särskilt ur ett elevperspek-tiv. / This study is based on empirical data from two completed focus groups that explore how stu-dents with mild intellectual disabilities in special secondary schools perceive the term “sär-skola”. A social constructionist perspective is used with particular specialization in theories of categorization. Study results were analyzed trough thematic content analysis and the result showed all participating students experienced disadvantages of the term “särskola”, which they wanted removed. The term contributed to thoughts and feelings of being inferior and deviant. The disadvantages students raised with the term were that it contributes to limits, bullying and stamping. One focus group felt that the school form as such is positive, while the other focus group felt that it is negative. Both groups highlighted that any other term than the existing would be better, but they preferred no special term at all. Concerns were raised that a changed terminology would not make any long-term difference. The study’s conclusions are that the terminology and society's attitudes should change. Particular attention should be paid to inform the professionals, who have contact with students in special curriculum, of students’ experiences of the term. Furthermore, the term should be studied further, particularly from a student perspective.

Die Überlebensrate von Reanimations-Patienten ist seit Jahrzehnten gleichbleibend gering. Die milde therapeutische Hypothermie (MTH) hat als bisher einzige Therapieoption gezeigt, dass das Gesamtüberleben und neurologische Outcome nach Wiedererlangen eines Kreislaufs signifikant verbessert wurde. Eine mögliche Kühlungsmethode ist die Hochvolumengabe 2-4°C kalter Infusionen zur Induktion und Aufrechterhaltung einer Körperkerntemperatur (KKT) von <34°C über 12-24 Stunden. Da nach kardiopulmonaler Reanimation häufig eine myokardiale Dysfunktion sowie eine systemische Entzündungsreaktion (SIRS) mit einhergehender Kreislaufinstabilität im Rahmen des Postreanimationssyndroms (PCAS) auftreten, könnten Bedenken bezüglich der Induktion eines Lungenödems bestehen. In dieser Arbeit wurde daher der Einfluss von kalten Infusionen auf die respiratorische Funktion untersucht. Ebenfalls wurde evaluiert, inwiefern sich die milde therapeutische Hypothermie auf die Katecholamin-Dosierung zur Kreislaufstabilisierung sowie auf Herz-Kreislauf-Parameter auswirkt. Dazu wurden retrospektiv die Daten von 166 Patienten bezüglich respiratorischer Parameter und von 159 Patienten bezüglich kardialer Parameter während des Kühlungszeitraums statistisch analysiert. Respiratorische Daten: Die Ejektionsfraktion (EF) betrug bei Aufnahme 34,8%. Dies entspricht einer mittelgradig eingeschränkten linksventrikulären (LV)-Funktion. Bei Ankunft auf der Intensivstation betrug der Horovitz-Quotient (PaO2/FiO2) als Maß für die Oxygenierungsfunktion der Lunge 210 mmHg bei einem PEEP von 7 mbar. Dies entspricht einem milden bis moderaten akuten Atemnotsyndrom (ARDS). Bis zu einer Zieltemperatur von ≤34°C (4,5 h) wurden 3.279 ml kaltes Volumen infundiert. Der Horovitz-Quotient verblieb dennoch unverändert bei 210 mmHg, der PEEP bei 7 mbar. Es zeigte sich ein schwacher, aber signifikanter, negativer linearer Zusammenhang zwischen Horovitz-Quotient und der Menge an infundiertem kaltem Volumen bei einer infundierten Flüssigkeitsmenge zwischen 0-11.000 ml. Diese Ergebnisse zeigen, dass die Oxygenierungsfunktion der Lunge durch die Volumengabe nicht beeinträchtigt wird. Dennoch sollten aufgrund des schwachen linearen Zusammenhangs von Infusionsmenge und Horovitz-Quotient die respiratorischen Parameter während der Gabe großer Mengen an kaltem Volumen engmaschig überwacht werden. Herz-Kreislauf-Daten: Initial bestand eine mittelgradig eingeschränkte LV-Funktion (EF 34,7%), die sich im Verlauf auf 41,5% verbesserte. Unter MTH konnte die Infusionsrate von Adrenalin signifikant reduziert werden, die Noradrenalin-Dosierung wurde hingegen signifikant erhöht. Die Herzfrequenz sank im gleichen Zeitraum signifikant. Diese Ergebnisse bestätigen vorherige Studien, die zeigen, dass die MTH eine positiv inotrope Wirkung besitzt und die HF senkt. Der zusätzliche Bedarf an Vasokonstriktoren ist wahrscheinlich auf eine im Rahmen des PCAS auftretende Vasodilatation zurückzuführen.

Introduction-Physical activity can reduce the risk of contracting many of the 'diseases of the sedentary', such as coronary heart disease and cancer (Blair et al., 1996). Recognition of this protective effect has led to the development of many programmes designed to promote the benefit of participation in sport and physical exercise (Hillary Commission, 1993; Nicholl et aI., 1995). With participation in sport, especially contact sport, the risk for injuries increases, including injuries to the head and neck (Wilberger, 1993; Wekesa et al., 1996; Pettersen, 2002). Mild traumatic brain injuries (MTBI) or concussion as used interchangeably in the literature (Maroon et al., 2000; Wills & Leathem, 2001) are an important public health concern, due to the high incidence and frequently persisting symptomatology (Evans, 1992). Mild traumatic brain injury is defined as a complex patho-physiological process affecting the brain induced by traumatic biomechanical forces (Aubry et al., 2002; McCrory et al., 2004). A sub-concussive injury or very mild traumatic brain injury (vMTBI) may be defined as an apparent brain insult with insufficient force to cause hallmark symptoms of concussion (Jordan, 2000; Webbe & Bath, 2003). The high incidence of sport related head injuries in South Africa is alarming, although the prevalence thereof is unknown and difficult to assess, as the seemingly trivial injuries frequently remain unreported (Roux et al., 1987). This is especially applicable in sport where a milder form of head injury is common. This is cause for concern as cumulative head injuries traditionally regarded as trivial or 'minor' may result in players running the risk of increasingly negative consequences following repetitive 'minor' head injuries. In contact sport such as rugby, players are at great risk of sustaining repetitive mild traumatic brain injuries. The negative outcome following these repetitive minor head injuries has been demonstrated by numerous studies on boxers and other athletes exposed to repeated MTBI and vMTBI (McLatchie et aI., 1987). The incidence of vMTBI has not yet been researched in school rugby and this study is the first to report the incidence of vMTBI in a secondary school rugby team. Obiectives - The objectives of this study were to determine the incidence, the neuropsychological consequences and the effect on the academic performance of repeated mild (MTBI) and very mild traumatic brain injuries (vMTBI) in a secondary school rugby team during one playing season. Methods - A cohort of 35 secondary school male rugby players divided into a vMTBI (group 1) (n=26) and a MTBI (group 2) (n=9) from a local secondary school's first and second team, was followed for a full competitive season by a trained Biokineticist, who was present at all the games and contact sessions played. All vMTBI and MTBI and the severity of these injuries were documented. A control (group 3) that consisted of 10 secondary school non-rugby players were compared with the vMTBI and MTBI groups. The incidence of repeated MTBI and vMTBI in a secondary school rugby team were gathered by questionnaires and observation next to the field by a trained Biokineticist. Pre-season and post-season neuropsychological tests were conducted on the research groups and the control group. The neuropsychological tests that were conducted on the three groups were the Colour Trial Test 1 and 2 (CTT 1 + 2), the Symbol Digit Modalities Test (SDMT), the Wechsler Memory Scale-Revised (WMS-R) and the Standardised Assessment of Concussion (SAC). After each match played throughout the season the research group also completed a SAC test. The academic results of the final examination (year 1) of the year of the specific rugby season were obtained, as well as the academic results of the final examination of the preceding two years (year 2 and 3). The programme STATISTICA (version 7.0, Stat soft, Tulsa, OK) was used to analyse the data. Descriptive statistics, one-way ANOVA's, two-way repeated measures ANOVA's, Post-hoc Tuckey HSD analysis and Pearson's product moment correlation were used for all the statistical analyses. Results - This study of a secondary school rugby team has shown 726 vMTBI's and 18 MTBI's throughout one rugby season. This relates to 1951 vMTBI's per 1000 player hours and 48 MTBI's per 1000 player hours. Reductions in delayed memory (p=O.O1)from preseason to post-season in a group of players with repetitive vMTBI's during a single rugby season were found. This was the first evidence of possible neurocognitive deficits towards delayed memory in very mild traumatic brain injuries at secondary school level. Statistically significant (p<=0.05)results of the SAC test totals between both the vMTBI and MTBI groups were documented in the different games throughout the rugby season and compared with the baseline test. No statistically significant differences (p<=0.05) between the pre-season and post-season's scores of the SAC test totals were documented. A decrease in academic performance in the subject Afrikaans (year 1 compared with year 2) with a p-value of p=O.O17(group 1) and p=O.O16(group 2) respectively was found. Conclusion - The findings of this study indicate a high incidence of vMTBI in a cohort of secondary school rugby players in one season, a statistically significant reduction (p=O.O1 )in delayed memory of the vMTBI rugby players and a statistically significant decrease in academic performance p=O.O17 (group 1) and p=O.O16 (group 2) in the subject Afrikaans from year 1 to year 2 final examinations. / Thesis (Ph.D. (Human Movement Science))--North-West University, Potchefstroom Campus, 2006.

Background: Parkinson’s disease (PD) is a chronic and progressive neurodegenerative disease. The diagnosis is based on a combination of the motor signs: tremor, bradykinesia, rigidity and postural abnormalities. Mild Cognitive Impairment (MCI) is common early in the disease and a large proportion of patients with PD develop dementia (PDD). Associations between motor symptoms and cognitive decline have been suggested but the results are inconclusive due to differences in the selection of participants and variables tested. Large population based studies with comprehensive neuropsychological investigation in newly diagnosed cases with PD followed prospectively are rare. The aim of this thesis was to improve characterization and understanding of cognition in PD, and to explore the relationship to motor impairment in the early phase of PD. Methods: All new patients with suspected idiopathic parkinsonism in the catchment area (142 ooo inhabitants) were examined during a period of five years and four months. Among other investigations, a comprehensive neuropsychological evaluation was carried out in 119 of 148 patients with PD together with 30 age matched healthy controls. Assessments were repeated after one three and five years. Results: Patients performed worse than healthy controls in a majority of neuropsychological tests. MCI at the time of diagnosis were found in 36% according to recently published MCI criteria. Thirty % were cognitively impaired using another definition. One fourth of the patients developed PDD within five years after diagnosis and 25 % of those with MCI at baseline reversed back to normal cognition. Age and MCI were significant predictors of dementia. Education was an independent predictor for severe cognitive dysfunction at diagnosis but did not predict PDD. Patients with MCI converting to PDD had worse performance on visuospatial function, semantic fluency, episodic memory, mental flexibility and conceptual thinking. There were no differences in cognitive performance between patients with predominant Postural and Gait Disturbances (PIGD) and the tremor dominant subtype at the baseline investigation and belonging to the PIGD subgroup at baseline did not predict PDD. Dementia converters declined more rapidly than non-converters in posture/gait function. Associations between bradykinesia and measures of executive functions and working memory were found, and between posture and gait disturbances and visuospatial function. Some of these associations were persistent after one year. Patients receiving the dopamine agonist pramipexole performed significantly worse on a measure of verbal fluency at the one year follow up. Conclusions: The differences in proportions of cognitively impaired in the different studies emphasize the value of joint criteria for PD-MCI. Even when using such criteria, a substantial proportion of patients revert back to normal function. The increase in motor disability in patients with PDD could have several different causes that need to be further investigated. Associated motor and cognitive dysfunctions could reflect common pathophysiological processes in partly shared networks. Both dopaminergic and non-dopaminergic motor and cognitive functions seems to be involved in PDD which suggests that pharmacological treatment in PD needs to go beyond the scope of dopaminergic deficiency in search for new therapies that would also be effective for non-motor symptoms. / NYPUM