Dissertationen zum Thema „Brain capacity“

Limited capacity for perception results in various phenomena of inattentional blindness in task conditions that load perceptual capacity. These effects have been extensively studied under the load theory framework, with numerous demonstrations spanning a wide variety of perceptual load manipulations. Research also established contrasting effects of loading perception versus cognitive control functions (e.g. working memory). The convergence of findings across different manipulations of perceptual load together with the contrasting effects of cognitive control load suggests a generalised capacity for perception, which is distinct from general cognitive capacity. The purpose of this thesis was to examine this hypothesis further, using an individual differences approach and relating traditional visual perception and awareness paradigms to the phenomenon of subitizing: the ability to detect a limited number of items in parallel from a brief exposure that has traditionally been studied within the enumeration literature. The research first extended perceptual load effects to measures of unattended processing in an enumeration paradigm, demonstrating that distractor effects are only found within subitizing capacity but not in set sizes that exceed capacity (Chapter 2). A series of individual differences experiments then revealed significant correlations between tasks involving subitizing, motion tracking, ‘change blindness’ and ‘inattentional blindness’. These relationships were furthermore established to withstand controls for non-perceptual factors, establishing perceptual capacity as distinct from working memory capacity or general cognitive effort (Chapters 3-4). Finally, voxel-based morphometry analyses of structural brain images established distinct correlates of grey matter density for perceptual capacity across tasks (Chapter 5). Taken together, the results of this thesis establish individual differences in perceptual capacity across a diverse range of paradigms and stimuli, demonstrating a common, general capacity limit for perception which correlates with individual differences in performance and grey-matter density and is independent from other cognitive constructs such as number estimation abilities and executive working memory.

This thesis consists of two volumes: a clinical and a research volume. The clinical volume contains five clinical practice reports; the research volume contains a systematic review and an empirical study. The systematic review explores the effectiveness of cognitive rehabilitation of problem-solving, planning and reasoning in people with traumatic brain injury. The findings suggest that Short-Term Executive Plus (STEP) can decrease executive dysfunction and improve problem-solving, however, more research would strengthen the findings. Evidence for the use of ‘gist reasoning’ training is growing. Training multitasking remains an approach with insufficient evidence to support it. Finally, although the findings in relation to telephone counselling seem promising, more research could help to clarify its effectiveness. The empirical study aimed to establish whether the Iowa Gambling Task (IGT) adds to the predictive potential of three tests of executive function in the assessment of capacity to take part in research in people with acquired brain injury. Stroop errors on the inhibition task and Wisconsin Card Sorting Test (WCST) total errors emerged as potential screening tools; the IGT was not among the predictors. Suggestions for future research are provided. Replication with a larger sample is needed to confirm the findings.

This study investigated, within the context of Brain Reserve Capacity (BRC) theory, whether repeated concussions resulted in residual deficits in cognitive and academic functioning of early adolescent rugby players relative to non-contact sports controls.

Les capacités de réserve cérébrale représentent les capacités de résilience du cerveau face à différents processus lésionnels comme ceux induit par la maladie d’Alzheimer (MA). Plusieurs hypothèses ont été proposées afin d’expliquer ce mécanisme. Les deux concepts les plus validés sont celui de la réserve cérébrale faisant référence au substrat cérébral et la réserve cognitive faisant référence à la fonctionnalité cérébrale. Les données épidémiologiques puis d’imagerie ont permis d’identifier des expériences de vie associées à de meilleures capacités de réserve cérébrale. Le niveau d’études, la profession exercée et la pratique d’activités de loisirs sont ainsi des indicateurs du niveau potentiel de capacités de réserve d’un sujet. L’objectif général de ce travail de thèse avait pour objectif de mieux caractériser les relations entre ces indicateurs et les capacités de réserve cérébrale. Tout d’abord, nous nous sommes intéressés à la relation entre ces expériences de vie et le substrat cérébral à partir de données d’imagerie recueillies au cours du suivi de la cohorte des 3 cités à Bordeaux. Nous avons ainsi montré que seul le niveau d’éducation était associé à des différences de volume de substance grise et de substance blanche entre les sujets de haut et bas niveau d’études. Par ailleurs, les sujets de haut niveau d’études présentaient une progression moindre en hypersignaux de substance blanche au cours du suivi de la cohorte des 3 cités indépendamment de la présence de facteurs de risque cardiovasculaires. Le niveau d’étude semble avoir une place non négligeable dans la constitution des capacités de réserve cérébrale et aussi bien dans la réserve cognitive que la réserve cérébrale. Ceci explique le rôle protecteur du niveau d’études vis à vis du risque de démence. Dans un 3ème travail, nous nous sommes servis de cette relation particulière entre le niveau d’études et la démence afin d’illustrer comment un facteur social peut être un facteur de maladie chronique liée à l’âge et comment en le modifiant, on peut éventuellement modifier la survenue de cette maladie. Enfin, nous nous sommes intéressés à la relation entre la pratique d’activités de loisirs au cours de la retraite et le risque de démence à partir des données de la cohorte Paquid. La pratique de jeux de société est associée à un moindre risque de démence mais le lien fort avec la cognition ne permet pas d’éliminer une causalité inverse. Cependant, un engagement plus important dans la pratique d’activités de loisirs au cours de la retraite est associé à un risque moindre de démence équivalent à des sujets ayant toujours pratiqué des activités. Des essais d’intervention permettraient de confirmer l’effet bénéfique de la pratique d’activités de loisirs sur la cognition et le risque de démence
The brain reserve capacities represent the resilience of the brain to cope against different pathological processes such as Alzheimer's disease (AD). Several hypotheses have been proposed to explain this mechanism. The two most validated concepts are the brain reserve referring to brain volume and cognitive reserve referring to brain function. Epidemiological and imaging data helped identify life experiences associated with better brain reserve capacities. Thus, the education, occupation and practice of leisure activities are recognized as proxies of the brain reserve capacities. The main objective of this thesis aimed to better characterize the relationship between these proxies and the brain reserve capacities. First, from brain imaging data collected during follow-up of the three cities cohort of Bordeaux, we examined the relationship between life experiences and brain volume. Only the education was associated with differences in gray and white matter volume. In addition, highly educated subjects had a smaller progression of white matter hyperintensities during the follow-up of this cohort independently of the presence of cardiovascular risk factors. Education seems to have a significant role in the formation of brain reserve capacities in both cognitive reserve and brain reserve. This explains the protective role of educational level against dementia. In a third work, we used this particular relationship between educational level and dementia to illustrate how a social factor can be a factor of a chronic disease related to aging and can modify the occurrence of this disease. Finally, we are interested in the relationship between the practice of leisure activities during retirement and the risk of dementia from data of Paquid study. The practice of playing board games is associated with a lower risk of dementia, but the strong link with cognition not eliminates reverse causality. However, a greater engagement in the practice of leisure activities in retirement is associated with a lower risk of dementia similar to subjects who always practiced activities. Intervention trials could confirm the beneficial effect of the practice of leisure activities on cognition and dementia risk

Since the introduction of helmets the incidence of traumatic brain injuries (TBI) in ice hockey has greatly decreased, but the incidence of concussions has essentially remained unchanged. Despite goaltenders in ice hockey being the only players on the ice for the entire game, few have assessed the performance of ice hockey goaltender masks. In ice hockey, goaltenders are exposed to impacts from collisions, falls and projectiles. The objective of this study was to assess the protective capacity of ice hockey goaltender masks for three accident events associated with concussion. A helmeted and unhelmeted medium NOCSAE headform were tested under conditions representing three common accident events in ice hockey. Falls were reconstructed using a monorail drop. A pneumatic linear impactor was used to reconstruct collisions and projectile impacts were reconstructed using a pneumatic puck launcher. Three impact locations and three velocities were selected for each accident event based on video analysis of real world concussive events. Peak resultant linear acceleration, peak resultant rotational acceleration and rotational velocity of the headform were measured. The University College Dublin Brain Trauma Model (UCDBTM) was used to calculate maximum principal strain (MPS) and von Mises stress in the cerebrum. The results demonstrated the importance of assessing the protective capacity of ice hockey goaltenders masks for each accident, as each event created a unique response. A comparison of unhelmeted and helmeted impacts revealed ice hockey goaltender masks are effective at reducing the risk of both concussion and TBI for falls and projectiles, but less so for collisions. Further, the risk of more serious injuries was found to increase for falls and collisions as impact velocity increased. The results highlight the importance of impacting multiple locations when assessing the protective capacity of ice hockey goaltenders masks, as different impact locations result in unique responses. Overall this study demonstrated ice hockey goaltenders masks capacity to reduce the risk of concussion across three accident events.

Heat stress and dehydration pose a severe challenge to physiological function and the capability to perform physical work. There is, however, limited knowledge on the regional haemodynamic and metabolic responses to strenuous exercise in environmentally stressful conditions. The primary aim of this thesis was to examine whether dehydration and heat stress compromise brain, muscle and systemic blood flow and metabolism, and whether depressed brain and muscle oxygen delivery underpin reduced exercise capacity during graded incremental and prolonged exercise. This thesis makes an original contribution to the knowledge by showing for the first time that dehydration markedly accelerates the decline in cerebral blood flow during maximal incremental (Chapter 4) and prolonged sub-maximal exercise (Chapter 5) in the heat. Cerebral metabolism, however, is preserved by compensatory increases in substrate extraction. Falling carbon dioxide tension underpinned the decline in CBF. However, a distinct regional distribution of blood flow across the head was observed, suggesting that different mechanisms are responsible for the regulation of regional blood flow within the head. A reduced cerebral metabolism is therefore an unlikely factor explaining the compromised exercise capacity in physiologically stressful hot environments. Rather, restrictions in active muscle blood flow and oxygen supply, which are not apparent during sub-maximal exercise, may explain the reduced maximal aerobic power in heat stressed conditions. For the first time we have manipulated skin and core temperature to show that combined internal and skin hyperthermia reduces maximal aerobic power in association with restrictions in limb, brain and systemic blood flow and skeletal muscle metabolism (Chapter 6). Overall, the findings of the present thesis provide novel information on how circulatory limitations across contracting skeletal muscle, brain and systemic tissues and organs might underpin the impairment in exercise capacity in physiologically taxing environments evoking significant dehydration and hyperthermia.

Aims

The aims of the thesis were to validate investigation instruments for stroke patients with dysphagia, and to improve oropharyngeal dysphagia therapies.

Methods/Results

A Lip Force Meter, LF 100, affirmed excellent intra- and inter-reliability, sensitivity and specificity. Controls had significantly stronger lip force (LF) and swallowing capacity (SC) than stroke patients. A normal lower limit of LF was set to 15 Newton. Dysphagia symptoms improved in 7 stroke patients after a 5-week sensorimotor stimulation therapy comprising manual body and facial regulation in combination with palatal plate application. Impaired LF and impaired SC were parallel phenomena in 22 acute stroke patients and did not differ regardless of presence or absence of facial palsy. LF and SC improved and were parallel phenomena in 30 stroke patients and did not differ regardless of presence or absence of facial palsy, time lag between stroke attack and start of treatment, or age. SC was normalized in 19 of 30 dysphagia patients after a 5-8-week daily lip muscle self-training with an oral screen.

Conclusions

LF100 is an appropriate and reliable instrument for measuring lip force. Dysphagia improvement, by body and facial sensorimotor stimulation in combination with palatal plate application, or by training with an oral screen is excellent examples of brain plasticity and cortical reorganisation. . Swallowing capacity and lip force in stroke patients are parallel phenomena. A sub clinical facial paresis seems to be present in most stroke patients. Training with an oral screen can improve LF and SC in stroke patients with oropharyngeal dysphagia.

Inom en snar framtid kan effektiva behandlingsmetoder mot antisocial personlighetsstörning komma att bli tillgängliga för användning. I denna uppsats driver jag en tes om hur vi på ett etiskt försvarbart sätt skulle kunna använda dessa metoder. Tesen begränsar sig till (1) tvångsbehandling (2) av våldsamma återfallsbrottslingar (3) som diagnostiserats med antisocial personlighetsstörning och psykopati, samt till (4) behandlingsmetoder som klassificeras som kapacitetsförbättringar riktade mot moralisk kompetens. Jag argumenterar för att vi har starka skäl att godta tesen, främst med hänseende på fördelarna det skulle innebära för patienten, potentiella brottsoffer, och samhället i stort. Jag diskuterar också de två allvarligaste invändningarna mot min tes – att behandlingen hotar patientens autonomi, respektive personliga identitet – men konstaterar slutligen att de inte tycks kunna falsifiera tesen.

Acquired brain injury (ABI) often results in prolonged periods of immobility which exacerbates physiological and psychological problems resulting from initial injury. A randomised controlled study had determined the effect of 3 months of exercise training on rehabilitation outcomes, impairment, mobility and activity in adults with ABI. This thesis reports changes in exercise capacity related to impairment, mobility and activity following exercise training during rehabilitation following ABI. Exercise capacity was compared using maximum oxygen uptake (VO2) and heart rate monitored graded exercise testing (HR GXT) with a cycle ergometer; changes in impairment were assessed by Motricity Index, isometric muscle strength; mobility with Berg Balance Scale, Rivermead Mobility Index, 10-m walk velocity; and activity with Functional Independence Measure , Barthel Index and Nottingham Extended Activities of Daily Living Index. Data was collected at 4 regional neurological rehabilitation units. Logistics, protocols and methodological issues associated with reliability were explored. Blind assessments were completed at baseline, 6 weeks (T2), at end of training 3 months (T3), and 3 months after training (T4) in 157 adults 43.2 ± 13.9 years old recruited 24.2 ± 14.7 weeks after a single incident ABI. Differences between VCh GXT and predicted maximal exercise data were found (p<0.000) and correlations (p<0.01-0.05) were established between VCh max and functional scores in a sample of the study population at baseline (n=43). After training, exercising subjects (n=20) increased their VChmax (p<0.02), cycled for longer and were more efficient than relaxation control subjects (n=22, p=0.03). Changes in HR GXT performance were examined in depth in a different subgroup (n=61) and exercising subjects (n=30) showed larger (p=0.02) increases at T3 than controls (n=31) for maximum work rate, but there were no associated changes in measures of impairment, mobility or activity. The improvements in exercise capacity were similar to changes seen in the VCh tested subjects. Comparison of HR GXT with VOi max testing validated the use of HR GXT in the clinic. Guidelines based on mobility and activity for selecting suitable patients for exercise testing are proposed and analysis of exercise training has provided guidelines for increasing exercise capacity. This study demonstrated that younger adults in the first year after ABI have markedly reduced exercise capacity which can be increased and responds normally to cycle ergometer training undertaken in the clinical setting.

Existing neurocomputational and empirical data link deficient neuromodulation of the fronto-parietal and hippocampal-striatal circuitries with aging-related increase in processing noise and declines in various cognitive functions. Specifically, the theory of aging neuronal gain control postulates that aging-related suboptimal neuromodulation may attenuate neuronal gain control, which yields computational consequences on reducing the signal-to-noise-ratio of synaptic signal transmission and hampering information processing within and between cortical networks. Intervention methods such as cognitive training and non-invasive brain stimulation, e.g., transcranial direct current stimulation (tDCS), have been considered as means to buffer cognitive functions or delay cognitive decline in old age. However, to date the reported effect sizes of immediate training gains and maintenance effects of a variety of cognitive trainings are small to moderate at best; moreover, training-related transfer effects to non-trained but closely related (i.e., near-transfer) or other (i.e., far-transfer) cognitive functions are inconsistent or lacking. Similarly, although applying different tDCS protocols to reduce aging-related cognitive impairments by inducing temporary changes in cortical excitability seem somewhat promising, evidence of effects on short- and long-term plasticity is still equivocal. In this article, we will review and critically discuss existing findings of cognitive training- and stimulation-related behavioral and neural plasticity effects in the context of cognitive aging, focusing specifically on working memory and episodic memory functions, which are subserved by the fronto-parietal and hippocampal-striatal networks, respectively. Furthermore, in line with the theory of aging neuronal gain control we will highlight that developing age-specific brain stimulation protocols and the concurrent applications of tDCS during cognitive training may potentially facilitate short- and long-term cognitive and brain plasticity in old age.

O declínio das capacidades motoras é inevitável ao longo do envelhecimento, porém, a curva desse declínio pode ser reduzida quando o exercício físico é utilizado como forma de intervenção. Em geral, envolvem a repetição de movimentos cíclicos e de baixa complexidade, com o objetivo de aumentar a eficiência fisiológica dos praticantes. Entretanto, há evidências que comprovam a plasticidade cerebral de animais, inclusive em animais idosos, que foram expostos a ambientes e experiências enriquecedoras. Estudos com humanos permitiram observar que os efeitos da aprendizagem de habilidades motoras estão associados a mudanças não apenas comportamentais, mas também nas estruturas cerebrais. Os resultados desses estudos têm sido discutidos em termos do esforço cognitivo relativo ao processo de aprendizagem e, em especial, das habilidades motoras complexas. Neste sentido, este estudo pretendeu verificar os efeitos de dois programas de exercícios físicos nas estruturas cerebrais e capacidades motoras de idosas. Mais especificamente, em uma situação experimental de ensino, foram aplicados dois programas de exercícios físicos, um voltado para a prática de habilidades motoras complexas e o outro voltado especificamente para a prática de movimentos de baixa complexidade (simples). Foram avaliados os efeitos desses programas sobre as estruturas cerebrais, por meio de ressonância magnética cerebral e, também, sobre as capacidades motoras, por meio de testes de capacidade funcional. Participaram do estudo 40 mulheres com idade média de 66,56 anos. Foram formados 3 grupos: Condicionamento Físico, Jogos e Controle. O programa de exercícios teve a duração de 14 semanas, com 3 sessões semanais. As avaliações ocorreram no início e no final dos programas nos 3 grupos. Os resultados revelaram que o grupo controle não apresentou mudanças significantes nas capacidades motoras nem em relação às estruturas cerebrais. O grupo Condicionamento Físico obteve melhora significante no desempenho dos testes de força de membros superiores, flexibilidade de membros inferiores e agilidade/equilíbrio dinâmico. Já o grupo Jogos demonstrou aumento significante no desempenho dos testes de flexibilidade de membros inferiores, agilidade/equilíbrio dinâmico e equilíbrio pé direito olho aberto. Entretanto, nenhum dos grupos, inclusive daqueles que praticaram exercícios físicos, apresentou mudanças significantes no que diz respeito às estruturas cerebrais. Concluiu-se que os programas de exercícios físicos foram parcialmente efetivos para a melhora das capacidades motoras, mas não promoveram alterações na estrutura cerebral
Although the diminishing in the motor abilities is inevitable along the aging process, the tendency of this decrease may be reduced when physical exercise is used as an intervention. These interventions, in general, include the repetition of movements which are cyclical and have low complexity, aiming to increase physiological efficiency of the practitioners. There are evidences of animal\'s brain plasticity, including elderly animals, which have been exposed to enriching environments and experiences. Studies with human beings have lead to the conclusion that the motor learning effects are associated to changes not only behavioral, but also in brain structure. The results of these studies have been discussed in terms of the cognitive effort related to the learning process and, specially, to the complex motor skills. Therefore this study aimed to verify the effects of two programs of physical exercises on the brain structure and motor capacities of elderly women. Specifically, in an experimental teaching condition, there have been developed two physical exercises programs: one oriented to the practice of complex motor skills; and the other directed to the practice of low complexity movements (simple). The effects of these programs in the brain structure have been evaluated through cerebral magnetic resonance and, also, in the motor capacities through functional capacities tests. Forty women with mean age of 66.56 years old have taken part of the study. There were three groups: Fitness, Games and Control. The exercises programs were developed during 14 weeks, with 3 sessions per week. The evaluations were in the beginning and in the end of the program. Results showed that the Control group has neither presented changes in their motor capacities nor related to their brain structures. The Fitness group significantly improved its performance in the tests for upper body strength, flexibility of the limbs and agility/ dynamic balance. The Games group demonstrated significant increase in the test for flexibility of the limbs, agility/dynamic balance and balance right foot open eye. Even though, none of the groups, including those which have practiced physical exercises, presented changes in their brain structures. In conclusion, the physical exercise programs have been partially effective for the improvement of the motor capacities, but have not brought changes in the brain structure

This dissertation examines the role of language directionality in conference interpret-ing in South Africa with the purpose of highlighting the need for bidirectional inter-preting in a South African context. Western mainstream doctrines prescribe for in-terpreters to work only towards their native (mother) tongue. However, in the multi-lingual South African context, where the majority of the population speaks at least two languages, the idea of language directionality has not been given much thought. Nevertheless, there seems to be a demand for bidirectional interpreters. The study aims to argue in favour of a language bi-directionality in interpreting through empha-sising its theoretical plausibility and practical evidence within the field of conference interpreting in South Africa. The dissertation is the result of an extended literature review and a survey carried out in South Africa in 2013 among conference interpreters working in the country.
Mini-dissertation (MA)--University of Pretoria, 2014.
tm2015
Modern European Languages
MA
Unrestricted

Rugby is a popular sport in South Africa, and has been played by young boys from as early as seven years old (South African Rugby Union [SARU], 2011). Despite various physical health benefits, it carries a high risk for injury, especially head injury, and consequently has a high incidence of concussion (Alexander, 2009; Laubscher, 2006; Shuttleworth-Edwards, Smith & Radloff, 2008). It is common for 12 to 13 per cent of adolescent rugby players to report mild traumatic brain injury or concussion per season (Laubscher, 2006; Shuttleworth-Edwards et al., 2008). The true incidence is however considered to be higher, even as high as 70.4% (Shuttleworth-Edwards et al., 2008). Concussion, otherwise known as mild traumatic brain injury (mTBI) is described as a traumatically induced alteration in mental status, or traumatically induced cerebral dysfunction (Kraus, McArthur, Silvermand & Jayaraman, 1996) which may, or may not involve loss of consciousness (Quality Standards Subcommittee, American Academy of Neurology [AAN], 1997). The nature of concussion has traditionally been considered to be transient, and symptoms are usually resolved within a few days or weeks (Kirkwood et al., 2008; Taylor et al., 2010). However, when concussions are not fully resolved prior to players returning to the game, they may be vulnerable to second impact syndrome. This syndrome causes herniation and brain oedema, which may result in death (Patel, 2005), as has been reported in South African press (Alexander, 2009; South African Press Association [SAPA], 2012). Even without second impact syndrome, repeated concussions may render the brain neurocognitively vulnerable, leading to an array of short- and long-term cognitive symptoms (Alexander, 2009; Shuttleworth-Edwards et al., 2008). Short-term problems include difficulties with attention, focus and concentration; following multi-step instruction, engaging in mental problem-solving; verbal expression, receiving and processing verbal and visual information; maintaining effective levels of mental and physical energy; controlling mood; suppressing impulsive behaviours; initiating and maintaining productive interpersonal relationships with peers; engaging in meaningful conversation and participating in group activities (Jantz & Coulter, 2007). Short-term cognitive impairments due to repeated concussion have also been found, and include amongst the former symptoms, also problems with delayed memory, learning, social functioning, and abstract thinking (Anderson, Brown, Newitt & Hoile, 2011; Laubscher, 2006). Long-term sequelae follow when children did not return to their baseline level of functioning after three months (Kirkwood et al., 2008; Taylor et al., 2010). Long-term sequelae include problems with memory, visuo-motor processing, executive functioning, learning and abstract thinking (Anderson, 2002; Anderson et al., 2010; Horton et al., 2010; Lezak et.al., 2004; Shuttleworth-Edwards & Radloff, 2008). As mTBI is traditionally thought to be of transient nature, researchers tend to investigate moderate to severe TBI, rather than mTBI (Alexander, 2009; Anderson et al., 2010; Patel, 2005). This could easily lead to important facts about mTBI being missed or not acknowledged. Nevertheless, recent investigations are uncovering facts about mTBI that could transform the way in which we understand mTBI, providing increasing evidence that mTBI is more serious than widely believed (Blakemore, 2012; Maxwell, 2011; Toleda et al., 2012). However, there remains a lack of research investigating mTBI from a single cause. Considering the above information, the current study provides unique information about mTBI. It specifically investigated the long-term effects of mTBI on adolescents from a homogenous cause, which makes results more comparable. The importance of this study is highlighted in the face of evidence for the long-term effects of multiple concussions, that were sustained during school rugby, on academic achievement (Alexander, 2009; Laubscher, 2006).In the light of grey areas in existing research, the aim of this current study was to investigate whether there is a significant difference in academic achievement within and between two groups of adolescents that had either played rugby and sustained multiple concussions, or had not played rugby nor sustained any concussions, when measured at four points in time over six years. A retrospective data-analysis was performed on matched, controlled, prospective longitudinal data, which was obtained from a study that evaluated the impact of repeated mTBI on the cognitive and academic functioning of early adolescent rugby players over time (Alexander, 2009). This study elaborates on a subset of the previous data, adding the gr. 12 results for academic aggregate scores, to the previously reported academic dataset. Participants were selected from Alexander‟s study (2009), and had either played rugby and obtained two or more concussions (Rugby/Concussed (RC- group); n=17), or did not play rugby nor sustained any concussions (Non-rugby/Non-concussed (NRC-group); n=13). Academic aggregate scores from baseline (gr. 7) through gr. 12 were analysed using quantitative statistical measures. A normal probability plot determined that the data was distributed normally. Descriptive statistics were reported, where after repeated measures ANOVA‟s were conducted to determine the statistical significance of differences in academic scores between and within the groups over time. These results indicated that the NRC-group displayed statistically significant increase in academic achievement over time (p = .000), whereas the RC-group did not display any significant differences, despite displaying a downwards trend in achievement. The difference between the two groups was measured at its highest in gr. 12 (p = .003), indicating that the NRC-group performed statistically significantly better than the RC-group over time. However, a Pearson‟s correlation test revealed that the estimated IQ (Vocabulary subscale of the WISC-III) (Wechsler, 1991) had a positive correlation on academic achievement [r(34) = .54, p < .05)]. To control for the effect that this correlation had on the academic results, an ANCOVA was conducted. This analysis indicated a statistically significant difference in academic achievement between the two groups in gr.12 (p = .004), with a large effect size (d = 1.41), implicating practical significance. Findings consequently confirmed our hypothesis. The significant increase in academic achievement observed within the NRC-group over time, is consistent with what could be expected if the brain is allowed to develop normally without disruption such as mTBI (Blakemore, 2012; Horton et al., 2010). The finding that the RC group did not display statistically significant intra-group differences in academic achievement when measured over time, but that academic achievement followed a downward trend, is difficult to substantiate in the literature. The few research studies on the effect of cumulative concussion on young athletes do not isolate academic achievement as a variable (Iverson et al., 2004; Shuttleworth-Edwards et al., 2008). Further research into intra-group differences in this specific area of enquiry and population group is therefore necessary. Normal cognitive and brain development, maintains that the brain develops in a posterior to anterior direction, and the prefrontal regions which are vulnerable to concussion, develop last (Anderson, 2010; Blakemore, 2012; Lezak, 2004). Whereas the primary motor and sensory areas and areas for receptive and expressive language are fully developed by the age of ten years, the prefrontal brain areas that are responsible for more complex and abstract thought repertoires only start maturing in early adolescence and this development continues up to the age of 24 and even into the early 30s (Toleda et al., 2012). Injury to the developing brain at this critical stage of maturation may adversely affect the development of cognitive skills, preventing the child from acquiring the effective cognitive strategies needed for normal academic functioning and adequate academic achievement after TBI (Horton et al., 2010). However, if there is no insult to the brain, cognitive functions are expected to develop normally as a result of synaptic pruning and increased white-matter volume in the prefrontal cortex (Blakemore, 2012), making it likely that the maturation of these abilities will lead to greater cognitive and academic ability (Blakemore & Choudhury, 2006), such as seen for the NRC-group in this study. Limitations for this study include a small sample size and the testing of only one variable. It is therefore recommended that future studies include more variables, and aim at creating a larger, randomized sample size, possibly providing a more representative pool of participants to study this phenomenon in South African context. It is also advised that future studies consider using neuropsychological measures to test cognitive functioning. As previous studies have indicated specific impairment in executive functioning after TBI, it may be worth researching the effect of concussion on executive functioning more thoroughly (Anderson, 2002; Anderson et al., 2010; Horton et al., 2010). Further it may be valuable to consider using functional MRI studies to broaden existing knowledge about the interaction between pathophysiology and cognitive functioning This study also highly recommends that schools and rugby clubs catering for child and adolescent players reconsider the importance of implementing proper return to play protocols after players obtain concussions.
Thesis (MA (Clinical Psychology))--North-West University, Potchefstroom Campus, 2013

Hur kan man genom grafisk design främja lärandet om en eller flera delar av hjärnans kapaciteter? Också, hur kan man genom grafisk design gynna utvecklingen av en eller flera delar av hjärnans kapaciteter? Med grafisk design har jag skapat ett verktyg som hjälper dig att planera dina studier samt hjälper dig att stimulera hjärnan inför studierna. Beteendedesign, metakognition och gamification är de teoretiska grunder arbetet vilar på. Jag vill uppmana dig som läser detta att reflektera kring din egen hjärnkapacitet. Upplever du ofta svårigheter med att fokusera, att sova eller kanske att planera? Det finns många sätt att stimulera hjärnan så att svårigheter kan bli lättare. Det sistnämnda är just det Charlie kan hjälpa dig med, att planera. En app som i nuläget är en prototyp hjälper dig att skapa vanor kringdina studier och utmanar dig att utveckla dina beteenden. Charlie uttryckeroch kombinerar planeringsverktyg och kunskap om hjärnstimulans på ett sätt som inte gjorts förut. Intrycket målgruppen får lämnar ett avtryck där beteendeförändring blir möjlig. Kunskap om och beteenden som främjar hjärnans kapacitet kombineras effektivt med de stunder då en använder stora delar av hjärnan, vilket gynnar förändringen i sig. Testa att utmana dig själv i vad din hjärna är kapabel till. Du sitter inte fast, du kan ändra dina vanor när du vill!
How can you through graphic design encourage schooling of one or multiple parts of the brain’s capacity? Furthermore, how can you through graphic design promote the evolvement of one or multiple parts of the brain’s capacity? With the help of graphic design, I have created a tool that helps you schedule your studies as well as it stimulates your brain pre-studying. Behavioral design, metacognition, and gamification are the theoretical foundations this study relies on. I want to encourage you, the one reading this, to reflect on your own brain capacity. Are you having a hard time focusing, sleeping, or planning things ahead? There are multiple ways to stimulate your brain so these difficulties become easier. The latter is the one Charlie can help you with, to plan ahead. An app, that’s currently a prototype, helps you create new habits around your studies, and challenges you to expand your behavior. Charlie, with the help of planning tools and knowledge about brain stimulation, coaches you in a way that’s never been done before. The impression my target group gets leaves a print where behavior change becomes a possibility. Knowledge about the behavior that encourages the brain’s capacity combined with the moments when we use most parts of our brain, benefits the evolution itself. Have the courage to challenge yourselves in what your brain is capable of. You’re not stuck, you can change your habits whenever you want!

In the first paper, the effects of trade openness and conflict risk on income inequality are investigated. I obtain that the effect of trade openness on inequality depends on the level of conflict risk. More precisely, there exists a threshold effect: trade openness worsens income inequality in countries where the risk of internal and external conflicts is high. Moreover, I find that countries with higher risk of conflicts are more unequal, and that more ethnically diverse countries increase income inequality. Finally, I obtain that democratic regimes decrease inequality. In the second paper, we analyze the general-equilibrium consequences of property right enforcement in the natural resource sector. Assuming that exclusion requires both private and public enforcement efforts, we compare states that differ by their ability to provide protection services. This ability is referred to as state capacity. We obtain that public protection services can effectively act as either substitutes or complements to private enforcement, and this strongly depends on state capacity. Under low state capacity, an increase in state protection services leads to a drop in national income as labor is drawn away from the directly productive activities. The opposite holds for high-capacity states. As a result, public protection services have an ambiguous effect on national income even though they can unambiguously increase resource rents. In the third paper, we argue that the right to hold dual citizenship can generate important social and economic benefits beyond its political dimension. We assemble a large panel dataset on dual citizenship. We find that in developing countries, dual citizenship recognition increases remittance inflows by US$1.19 billion, GDP and household consumption, and improves child survival. In developed countries, however, dual citizenship recognition decreases remittance inflows by US$1.44 billion, but increases FDI by US$828 billion, raises household consumption, gross capital formation and trade, and provides incentives for skilled workers to move to other countries.

The main objective of this study was to investigate the fibers and their effects and availability in ketchup (tomato fiber) and cake (wheat bran fiber) production. In order to this, rheological properties of ketchups with tomato fiber, and cake (100, 80, 60 g flour formulations) with wheat bran fiber in different concentrations were investigated. Tomato powder in ketchup and wheat bran in cake was used for comparison. The samples studied had pseudoplastic behavior having a definite yield stress with a good fit for the Herschel-Bulkley model. The viscosity and yield stress values increased as the percentage of fiber increased. Moreover the samples were found to be more elastic than viscous (G&rsquo
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values increased with oscillatory frequency, percentage of fiber, and in cake samples decreased as the amount of flour decreased. Stability measurements of ketchups studied were done by using Lumisizer. The microstructure of tomato powder, wheat bran and fibers were investigated under SEM. It was seen that the fibers had branched, long and thin structure while the other two had lumy and thick structure. The pressure used, resulted in this structure with increased surface area and finally increased water holding capacity in fibers. Moreover, texture of cakes prepared was all investigated in terms of volume, outer surface, hardness, cohesiveness and gumminess. Finally it was found to be possible to produce healthier ketchups and cakes with fiber in a good quality by decreasing the other undesired ingredients.

Le génome des rotavirus (RV) comporte 11 segments d’ARN double brin. Dans des conditions de haute multiplicité d’infection, un dysfonctionnement de l’ARN polymérase virale peut induire le réarrangement d’un segment d’ARN par duplication partielle de sa séquence. In vivo, la survenue de réarrangements n’a été décrite qu’au cours d’infections chroniques chez des enfants immunodéprimés. Nous avons caractérisé les segments 7 et 11 réarrangés (7R et 11R) d’une souche de RV humain. Nous avons montré que le segment 7R n’était pas stable lors de la propagation du virus en culture et subissait une délétion aboutissant à l’expression d’une protéine NSP3 modifiée. L’analyse des séquences des segments 7R et 11R nous a permis de proposer un mécanisme théorique du réarrangement, fondé sur les structures secondaires des ARNm. Nous avons ensuite montré que des réarrangements du segment 11 pouvaient survenir lors d’infections aiguës à RV chez des enfants immunocompétents. Ces réarrangements surviennent en des points précis de la séquence au niveau de courtes répétitions, qui pourraient intervenir dans le mécanisme du réarrangement. Lors de l’infection aiguë, les virus à génome réarrangé restent très minoritaires par rapport aux virus sauvages, peut-être du fait d’une vitesse de réplication virale amoindrie. Nous avons montré que les RV à segment 7R avaient une cinétique de réplication inférieure ou égale à celle de virus sauvages. Paradoxalement, lorsque ces virus sont mis en compétition avec des virus sauvages, le segment 7R est sélectionné dans la descendance virale, suggérant une encapsidation préférentielle du segment réarrangé par rapport à son homologue normal lors de la réplication.

Conselho Nacional de Desenvolvimento Científico e Tecnológico
Two experiments were carried out in Rabbit Laboratory of Animal Science Department at Federal University of Santa Maria, RS, where were studied the influence of different fractions of fiber from agricultural by-products (citrus pulp, soybean hulls, linseed bran and corn gluten meal) on performance, digestibility coefficients, blood parameters and meat quality of rabbits submitted to diets. The diets were isoproteic and isoenergetic, 18% of crude protein and 3,000 kcal/kg of digestible energy, respectively. Eight New Zealand White rabbits were utilized to each treatment, from 40 to 89 days of age. At the first experiment, the treatments were: AHcontrol diet, with alfalfa hay; CP- total substitution of alfalfa hay by citrus pulp and SH- total substitution of alfalfa hay by soybean hulls. The animals of the treatments CP and SH showed similar performance, carcass weight and carcass dressing percentage to the animals of the treatment AH. The DM, OM, CP and NDF apparent digestibility coefficients were superior for the diet SH, due to fiber quality. Reductions on triglycerides, cholesterol, hemoglobin and glucose levels were observed in the blood of the animals fed with citrus pulp, because of the high cation-exchange capacity of this by-product. Meat tenderness was higher for those animals that consumed the diet with soybean hulls, due to better nutrients digestibility. The different fiber fractions from citrus pulp and soybean hulls do not affect animals performance and weight and dressing carcass, showing that these ingredients can substitute the alfalfa hay on rabbits diet. Fiber quality of citrus pulp decrease animals blood triglycerides and cholesterol levels. The lower amount of lignin in relation to cellulose and hemicellulose of the soybean hulls provides better nutrients digestibility coefficients. At the second experiment the treatments were: AH- control diet, with alfalfa hay; LB- total substitution of alfalfa hay by linseed bran and GM- total substitution of alfalfa hay by corn gluten meal (20% of crude protein). The animals from GM treatment showed similar performance in relation to the ones from AH treatment, although the carcass dressing percentage did not differ among the byproducts. Linseed bran proportioned lower performance, due to higher fiber hydration capacity and gel formation. The DM, OM, CP and NDF apparent digestibility coefficients were superior for GM treatment, due to fiber quality. Meat tenderness was higher for those animals that consumed the diet of the treatment GM because of the better digestibility coefficients. Corn gluten meal can substitute alfalfa hay on rabbits diet. Linseed bran, due to high amount of soluble fiber and high hydration capacity, affects animal performance and meat tenderness.
Dois experimentos foram realizados no Laboratório de Cunicultura do Departamento de Zootecnia, da Universidade Federal de Santa Maria, RS, onde se estudou a influência das diferentes frações de fibra advindas de co-produtos agroindustriais (polpa de citros, casca de soja, farelo de linhaça e farelo proteinoso de milho) sobre o desempenho, coeficientes de digestibilidade, parâmetros sanguíneos e características da carne de coelhos submetidos às dietas. As dietas foram isoprotéicas (18% PB) e isoenergéticas (3000 kcal/kg ED). Foram utilizados oito coelhos da raça Nova Zelândia Branca por tratamento, testados dos 40 aos 89 dias de idade. No primeiro experimento, os tratamentos foram: FA- ração controle, com feno de alfafa; PC- substituição total do feno de alfafa por polpa de citros e CS- substituição total do feno de alfafa por casca de soja. Os animais dos tratamentos PC e CS apresentaram desempenho, peso e rendimento de carcaça semelhantes aos animais do tratamento FA. Os coeficientes de digestibilidade aparente da MS, MO, PB e FDN foram superiores para a dieta com casca de soja, em função da qualidade de fibra deste ingrediente. Foi observado redução nos níveis séricos de triglicerídeo, colesterol, hemoglobina e glicose dos animais alimentados com polpa de citros, devido à alta capacidade de ligação catiônica deste co-produto. A maciez da carne foi superior para os animais que consumiram a dieta com casca de soja, em virtude da melhor digestibilidade dos nutrientes. As diferentes frações da fibra advindas da polpa de citros e casca de soja não afetam o desempenho dos animais e o peso e rendimento de carcaça, mostrando que estes ingredientes podem substituir o feno de alfafa na dieta de coelhos. A qualidade de fibra da polpa de citros reduz os níveis séricos de triglicerídeo e colesterol dos animais. A baixa quantidade de lignina em relação à celulose e hemicelulose da casca de soja propicia melhores coeficientes de digestibilidade dos nutrientes. No segundo experimento, os tratamentos foram: FA- ração controle, com feno de alfafa; FL- substituição total do feno de alfafa por farelo de linhaça e FP- substituição total do feno de alfafa por farelo proteinoso de milho (20% PB). Os animais do tratamento FP apresentaram desempenho semelhante aos animais do tratamento FA. Porém, o rendimento de carcaça não diferiu entre os co-produtos testados. O farelo de linhaça proporcionou desempenho inferior aos demais ingredientes, devido à alta capacidade de hidratação da fibra e formação de gel. Os coeficientes de digestibilidade aparente da MS, MO, PB e FDN foram superiores para o tratamento FP, em função da qualidade de fibra. A maciez da carne foi superior para os animais que consumiram a dieta do tratamento FP, em virtude da melhor digestibilidade dos nutrientes. O farelo proteinoso de milho pode substituir o feno de alfafa na dieta de coelhos. O farelo de linhaça, pela grande quantidade de fibra solúvel e alta capacidade higroscópica, prejudica o desempenho dos animais e maciez da carne.

The desire to enhance and make ourselves better is not a new one and it has continued to intrigue throughout the ages. Individuals have continued to seek ways to improve and enhance their well-being for example through nutrition, physical exercise, education and so on. Crucial to this improvement of their well-being is improving their ability to remember. Hence, people interested in improving their well-being, are often interested in memory as well. The rationale being that memory is crucial to our well-being. The desire to improve one’s memory then is almost certainly as old as the desire to improve one’s well-being. Traditionally, people have used different means in an attempt to enhance their memories: for example in learning through storytelling, studying, and apprenticeship. In remembering through practices like mnemonics, repetition, singing, and drumming. In retaining, storing and consolidating memories through nutrition and stimulants like coffee to help keep awake; and by external aids like notepads and computers. In forgetting through rituals and rites. Recent scientific advances in biotechnology, nanotechnology, molecular biology, neuroscience, and information technologies, present a wide variety of technologies to enhance many different aspects of human functioning. Thus, some commentators have identified human enhancement as central and one of the most fascinating subject in bioethics in the last two decades. Within, this period, most of the commentators have addressed the Ethical, Social, Legal and Policy (ESLP) issues in human enhancements as a whole as opposed to specific enhancements. However, this is problematic and recently various commentators have found this to be deficient and called for a contextualized case-by-case analysis to human enhancements for example genetic enhancement, moral enhancement, and in my case memory enhancement (ME). The rationale being that the reasons for accepting/rejecting a particular enhancement vary depending on the enhancement itself. Given this enormous variation, moral and legal generalizations about all enhancement processes and technologies are unwise and they should instead be evaluated individually. Taking this as a point of departure, this research will focus specifically on making a case for ME and in doing so assessing the ESLP implications arising from ME. My analysis will draw on the already existing literature for and against enhancement, especially in part two of this thesis; but it will be novel in providing a much more in-depth analysis of ME. From this perspective, I will contribute to the ME debate through two reviews that address the question how we enhance the memory, and through four original papers discussed in part three of this thesis, where I examine and evaluate critically specific ESLP issues that arise with the use of ME. In the conclusion, I will amalgamate all my contribution to the ME debate and suggest the future direction for the ME debate.

Due to physical, cognitive and emotional impairments, many individuals are unemployed or under-employed following a traumatic brain injury. The research evidence links the rigour of a vocational evaluation to future employment outcomes. Despite this link, no specific guidelines exist for vocational evaluations. Using the research evidence and a diverse panel of clinical and academic experts, the primary objective of this doctoral research was to develop an inter-professional clinical practice guideline for vocational evaluation following traumatic brain injury. The objective of the guideline is to make explicit the processes and factors relevant to vocational evaluation, to assist evaluators (i.e. clients, health and vocational professionals, and employers) in collaboratively determining clients’ work abilities and developing recommendations for work entry, re-entry or vocational planning. The steps outlined in the Canadian Medical Association's Handbook on Clinical Practice Guidelines were utilized to develop the guideline and include the following: 1) identifying the guideline’s objective/questions; 2) performing a systematic literature review; 3) gathering a panel; 4) developing recommendations; 4) guideline writing; 5) pilot testing. The resulting guideline includes 17 key recommendations within the following seven domains: 1) evaluation purpose and rationale; 2) initial intake process; 3) assessment of the personal domain; 4) assessment of the environment; 5) assessment of occupational/job requirements; 6) analysis and synthesis of assessment results; and 7) development of evaluation recommendations. Results from an exploratory study of the guideline’s implementation by occupational therapists in their daily practices revealed that clinicians used the guideline to identify practice gaps, systematize their evaluation processes, enhance inter-professional and inter-stakeholder communication, and re-conceptualize their vocational evaluations across disability groups. Statistically significant improvements were also noted in clients’ participation scores on the Mayo-Portland Adaptability Inventory–4 following guideline use. This guideline may be applicable to individuals with TBI, clinicians, health and vocational professionals, employers, professional organizations, administrators, policy makers and insurers.

Introduction: Internal Carotid Stump Syndrome may be one of the possible causes of ischemic stroke (iCMP), as well as retinal infarction (RI). Syndrome of the occluded internal carotid (ACI) (stump syndrome) is a nosological unit, which is characterized by an onset of ipsilateral iCMP or RI of thromboembolic ethiology in patients with occlusion of ACI via the externa carotid or arteria ophthalmica. In my thesis, I have concentrated upon the specification of the stump syndrome, its diagnostics and treatment; furthermore I have assessed the appropriateness of surgical approach in comparison with conservative approach. Material and methods: A total of 621 patients with occlusion were treated in two centres in the course of five years. In a group of 40 patients, the ACI occlusion was detected sonographically, the length of the occluded ACI being >5 mm, with normal vasoreactivity based upon SPECT CO2 and excluded cardiogenic cause of iCMP. The patients were divided in two groups - surgical and conservative. Patients were monitored in 6-month intervals for the total period of four years. Results: No RI or iCMP were detected in the surgical group; one patient died six months after surgery. We observed one case of amaurosis fugax in the conservative group. Conclusion: Ultrasound examination is a fully sufficient...

Pour être performant au plus haut niveau, les athlètes doivent posséder une capacité perceptivo-cognitive supérieure à la moyenne. Cette faculté, reflétée sur le terrain par la vision et l’intelligence de jeu des sportifs, permet d’extraire l’information clé de la scène visuelle. La science du sport a depuis longtemps observé l’expertise perceptivo-cognitive au sein de l’environnement sportif propre aux athlètes. Récemment, des études ont rapporté que l’expertise pouvait également se refléter hors de ce contexte, lors d’activités du quotidien par exemple. De plus, les récentes théories entourant la capacité plastique du cerveau ont amené les chercheurs à développer des outils pour entraîner les capacités perceptivo-cognitives des athlètes afin de les rendre plus performants sur le terrain. Ces méthodes sont la plupart du temps contextuelles à la discipline visée. Cependant, un nouvel outil d’entraînement perceptivo-cognitif, nommé 3-Dimensional Multiple Object Tracking (3D-MOT) et dénué de contexte sportif, a récemment vu le jour et a fait l’objet de nos recherches. Un de nos objectifs visait à mettre en évidence l’expertise perceptivo-cognitive spécifique et non-spécifique chez des athlètes lors d’une même étude. Nous avons évalué la perception du mouvement biologique chez des joueurs de soccer et des non-athlètes dans une salle de réalité virtuelle. Les sportifs étaient systématiquement plus performants en termes d’efficacité et de temps de réaction que les novices pour discriminer la direction du mouvement biologique lors d’un exercice spécifique de soccer (tir) mais également lors d’une action issue du quotidien (marche). Ces résultats signifient que les athlètes possèdent une meilleure capacité à percevoir les mouvements biologiques humains effectués par les autres. La pratique du soccer semble donc conférer un avantage fondamental qui va au-delà des fonctions spécifiques à la pratique d’un sport. Ces découvertes sont à mettre en parallèle avec la performance exceptionnelle des athlètes dans le traitement de scènes visuelles dynamiques et également dénuées de contexte sportif. Des joueurs de soccer ont surpassé des novices dans le test de 3D-MOT qui consiste à suivre des cibles en mouvement et stimule les capacités perceptivo-cognitives. Leur vitesse de suivi visuel ainsi que leur faculté d’apprentissage étaient supérieures. Ces résultats confirmaient des données obtenues précédemment chez des sportifs. Le 3D-MOT est un test de poursuite attentionnelle qui stimule le traitement actif de l’information visuelle dynamique. En particulier, l’attention sélective, dynamique et soutenue ainsi que la mémoire de travail. Cet outil peut être utilisé pour entraîner les fonctions perceptivo-cognitives des athlètes. Des joueurs de soccer entraînés au 3D-MOT durant 30 sessions ont montré une amélioration de la prise de décision dans les passes de 15% sur le terrain comparés à des joueurs de groupes contrôles. Ces données démontrent pour la première fois un transfert perceptivo-cognitif du laboratoire au terrain suivant un entraînement perceptivo-cognitif non-contextuel au sport de l’athlète ciblé. Nos recherches aident à comprendre l’expertise des athlètes par l’approche spécifique et non-spécifique et présentent également les outils d’entraînements perceptivo-cognitifs, en particulier le 3D-MOT, pour améliorer la performance dans le sport de haut-niveau.
To perform at the top, athletes must possess a special perceptual-cognitive ability. This talent is the capacity to extract key information from a visual scene and is reflected by sportsmen’s vision and intelligence of play. For a long time, sport science has reported perceptual-cognitive expertise inside the domain-specific sport environment of athletes. But more recently, evidence has shown that expertise could also been reflected outside of this context, in daily activities for instance. Moreover, recent theories surrounding brain plasticity have driven researchers to develop new tools to train perceptual-cognitive skills of athletes in order to increase performance on the field. Those methods are mostly contextual to the athlete’s discipline. However, a new perceptual-cognitive training methodology, called 3-Dimensional Multiple Object Tracking (3D-MOT), which is deprived of sport context, has recently been developed and took a center part in our researches. One of the main objectives was to observe athletes’ specific and non-specific expertise during the same study. We evaluated biological motion perception in soccer players and non-athletes in a virtual reality environment. Sportsmen were systematically more efficient and faster compared to novices when discriminating the direction of the biological motion during a soccer specific exercise (shot) but also during a daily action (walk). The results suggest that athletes are better capable in perceiving human biological motions performed by others. Soccer activity seems to confer a fundamental advantage that goes beyond sport specific functions. Concurrent with those discoveries, we observed the amazing ability of an athlete’s performance to process dynamic and neutral visual scenes. Soccer players outperformed novices throughout the 3D-MOT test which consists in tracking moving targets and simulates perceptual-cognitive skills. Their visual tracking speed and their learning ability were superior. The results confirm previous data obtained by sport experts. The 3D-MOT is an attentional tracking paradigm that stimulates active processing of dynamic visual information. In particular, it targets selective, dynamic and sustained attention, as well as working memory. This tool can be used to train perceptual-cognitive functions of athletes. Soccer players trained with the 3D-MOT throughout 30 sessions have shown an increase in passing decision making (15%) on the field compared to control groups. For the first time, the results demonstrate a perceptual-cognitive transfer from the laboratory to the field following a non-contextual perceptual-cognitive training program. Our research helps to understand athletes’ expertise by using both specific and non-specific approaches and also present perceptual-cognitive training tools, in particular the 3D-MOT technique, to improve performance in sport.

About 50 million people worldwide suffer from epilepsy and one third of them have seizures that are refractory to medication. In the past few decades, deep brain stimulation (DBS) has been explored by researchers and physicians as a promising way to control and treat epileptic seizures. To make the DBS therapy more efficient and effective, the feedback loop for titrating therapy is required. It means the implantable DBS devices should be smart enough to sense the brain signals and then adjust the stimulation parameters adaptively. This research proposes a signal-sensing channel configurable to various neural applications, which is a vital part for a future closed-loop epileptic seizure stimulation system. This doctoral study has two main contributions, 1) a micropower low-noise neural front-end circuit, and 2) a low-power configurable neural recording system for both neural action-potential (AP) and fast-ripple (FR) signals. The neural front end consists of a preamplifier followed by a bandpass filter (BPF). This design focuses on improving the noise-power efficiency of the preamplifier and the power/pole merit of the BPF at ultra-low power consumption. In measurement, the preamplifier exhibits 39.6-dB DC gain, 0.8 Hz to 5.2 kHz of bandwidth (BW), 5.86-μVrms input-referred noise in AP mode, while showing 39.4-dB DC gain, 0.36 Hz to 1.3 kHz of BW, 3.07-μVrms noise in FR mode. The preamplifier achieves noise efficiency factor (NEF) of 2.93 and 3.09 for AP and FR modes, respectively. The preamplifier power consumption is 2.4 μW from 2.8 V for both modes. The 6th-order follow-the-leader feedback elliptic BPF passes FR signals and provides -110 dB/decade attenuation to out-of-band interferers. It consumes 2.1 μW from 2.8 V (or 0.35 μW/pole) and is one of the most power-efficient high-order active filters reported to date. The complete front-end circuit achieves a mid-band gain of 38.5 dB, a BW from 250 to 486 Hz, and a total input-referred noise of 2.48 μVrms while consuming 4.5 μW from the 2.8 V power supply. The front-end NEF achieved is 7.6. The power efficiency of the complete front-end is 0.75 μW/pole. The chip is implemented in a standard 0.6-μm CMOS process with a die area of 0.45 mm^2. The neural recording system incorporates the front-end circuit and a sigma-delta analog-to-digital converter (ADC). The ADC has scalable BW and power consumption for digitizing both AP and FR signals captured by the front end. Various design techniques are applied to the improvement of power and area efficiency for the ADC. At 77-dB dynamic range (DR), the ADC has a peak SNR and SNDR of 75.9 dB and 67 dB, respectively, while consuming 2.75-mW power in AP mode. It achieves 78-dB DR, 76.2-dB peak SNR, 73.2-dB peak SNDR, and 588-μW power consumption in FR mode. Both analog and digital power supply voltages are 2.8 V. The chip is fabricated in a standard 0.6-μm CMOS process. The die size is 11.25 mm^2. The proposed circuits can be extended to a multi-channel system, with the ADC shared by all channels, as the sensing part of a future closed-loop DBS system for the treatment of intractable epilepsy.

Chronic recording of neural signals is indispensable in designing efficient brain machine interfaces and to elucidate human neurophysiology. The advent of multi-channel micro-electrode arrays has driven the need for electronic store cord neural signals from many neurons. The continuous increase in demand of data from more number of neurons is challenging for the design of an efficient neural recording frontend(NRFE). Power consumption per channel and data rate minimization are two key problems which need to be addressed by next generation of neural recording systems. Area consumption per channel must be low for small implant size. Dynamic range in NRFE can vary with time due to change in electrode-neuron distance or background noise which demands adaptability. In this thesis, techniques to reduce power-per-channel and area-per-channel in a NRFE, via new circuits and architectures, are proposed. An area efficient low power neural LNA is presented in UMC 0.13 μm 1P8M CMOS technology. The amplifier can be biased adaptively from 200 nA to 2 μA , modulating input referred noise from 9.92 μV to 3.9μV . We also describe a low noise design technique which minimizes the noise contribution of the load circuitry. Optimum sizing of the input transistors minimizes the accentuation of the input referred noise of the amplifier. It obviates the need of large input coupling capacitance in the amplifier which saves considerable amount of chip area. In vitro experiments were performed to validate the applicability of the neural LNA in neural recording systems. ADC is another important block in a NRFE. An 8-bit SAR ADC along with the input and reference buffer is implemented in 0.13 μm CMOS technology. The use of ping-pong input sampling is emphasized for multichannel input to alleviate the bandwidth requirement of the input buffer. To reduce the output data rate, the A/D process is only enabled through a proposed activity dependent A/D scheme which ensures that the background noise is not processed. Based on the dynamic range requirement, the ADC resolution is adjusted from 8 to 1 bit at 1 bit step to reduce power consumption linearly. The ADC consumes 8.8 μW from1Vsupply at1MS/s and achieves ENOB of 7.7 bit. The ADC achieves FoM of 42.3 fJ/conversion in 0.13 μm CMOS technology. Power consumption in SARADCs is greatly benefited by CMOS scaling due to its highly digital nature. However the power consumption in the capacitive DAC does not scale as well as the digital logic. In this thesis, two energy-efficient DAC switching techniques, Flip DAC and Quaternary capacitor switching, are proposed to reduce their energy consumption. Using these techniques, the energy consumption in the DAC can be reduced by 37 % and 42.5 % compared to the present state-of-the-art. A novel concept of code-independent energy consumption is introduced and emphasized. It mitigates energy consumption degradation with small input signal dynamic range.

The main aim of this study was to classify and describe the plant communities in the home range of white rhinoceros in order to understand the animal seasonal foraging ecology. To provide a detailed habitat description, forty sample plots were stratified randomly. A TWINSPAN classification, refined by Braun-Blanquet procedures, was carried out on the Viewpoint section of the reserve. Ten plant communities, grouped into five major community types, were identified. The veld condition and ecological carrying capacity in these communities were measured, stating an abundance of food on long grass while the short grass equal the number of short grass feeders. A number of behavioural aspects such as activity data, home range utilization and dietary usage were examined. Statistical methods such as the Spearman rank-order correlation, Wilcoxon sign test and Student T-test were used on rhino data. The difference in usage of the home range during wet and dry seasons was insignificant.
Environmental Sciences
M.Sc. (Environmental Management)

The main aim of this study was to classify and describe the plant communities in the home range of white rhinoceros in order to understand the animal seasonal foraging ecology. To provide a detailed habitat description, forty sample plots were stratified randomly. A TWINSPAN classification, refined by Braun-Blanquet procedures, was carried out on the Viewpoint section of the reserve. Ten plant communities, grouped into five major community types, were identified. The veld condition and ecological carrying capacity in these communities were measured, stating an abundance of food on long grass while the short grass equal the number of short grass feeders. A number of behavioural aspects such as activity data, home range utilization and dietary usage were examined. Statistical methods such as the Spearman rank-order correlation, Wilcoxon sign test and Student T-test were used on rhino data. The difference in usage of the home range during wet and dry seasons was insignificant.
Environmental Sciences
M.Sc. (Environmental Management)