Age-related physical and cognitive changes hinder the ability of older adults to operate smartphones. While many user interface (UI) heuristics exist today, there is a need for an updated set designed specifically to assess the usability of mobile devices for an older audience. Smartphone evaluation heuristics for older adults based on age-related changes in vision, hearing, attention, memory and motor control were developed in this thesis by analyzing literature on age-related physical and cognitive changes impacting smartphone usability. Support for heuristics was found by gathering information on how older adults use cell phones through interviews and an online survey. It was demonstrated that strength of support for some heuristics increases with age. The evaluated heuristics provide usability practitioners and designers with a framework for evaluating the usability of smartphones for older adults.

The visual system and good ocular motor control play an important role in the effective development of gross motor, sport, fine motor and academic skills (Erhardt et al., 1988:84; Desrocher, 1999:36; Orfield, 2001:114). Various researchers report a link between ocular motor problems and attention–deficit hyperactivity disorder (ADHD) (Cheatum & Hammond, 2000:263; Farrar et al., 2001:441; Gould et al., 2001:633; Armstrong & Munoz, 2003:451; Munoz et al., 2003:510; Borsting et al., 2005:588; Hanisch et al., 2005:671; Mason et al., 2005:1345; Loe et al., 2009:432). A few studies were carried out to analyse the links between ADHD and ocular motor control with regard to matters like visual attention, visual perception and ocular motor control like eye movement outside the normal fixation point, but no studies have been reported on the status of the ocular motor control of South African populations, and the effect of visual–motor intervention on the ocular motor control or visual–motor integration of learners with ADHD. The aim of the study was twofold, namely firstly to determine the ocular motor control functions and status of visual–motor integration of a selected group of 6– tot 8–year–old learners with ADHD in Brakpan, South Africa, while the second aim was to determine whether a visualmotor– based intervention programme can improve the ocular motor control and status of the visual–motor integration of a selected group of 6– to 8–year–old learners with ADHD in Brakpan, South Africa. Statistica for Windows 2010 was used to analyse the data. The Sensory Input Screening measuring instrument and the Quick Neurological Screening Test II (QNST–II) were used to assess the ocular motor control functions (fixation, ocular alignment, visual tracking and convergence–divergence), while the Beery Developmental Test of Visual–Motor Integration (VMI–4de weergawe) was used to determine the status of the learners’ visual–motor integration (VMI), visual perception (VP) and motor coordination (MC). The Disruptive Behaviour Scale, a checklist for ADHD (Bester, 2006), was used as measuring instrument to identify the learners with ADHD. Fifty–six learners (31 boys, 25 girls, with an average age of 7,03 years +0,65) participated in the pre–test and were divided into an ADHD (n=39) and a non–ADHD (n=16) group for aim one. Two–way tables were used to determine the percentage of ocular motor control deficits in the learners with and without ADHD, and an independent t–test was used to analyse the visual–motor integration of these learners. The Pearson Chi–squared test was used to determine the practical significance of differences in VMI and VP (d>0,05). The results of the study reveal that the majority of learners displayed ocular motor control deficits, regardless of whether they were classified with ADHD or not. The biggest percentage of learners fell into Class 2 (moderate deficits), particularly with regard to horizontal (68,57%; 52,63%; w=0,16) and vertical tracking (65,71%; 73,68%), as well as convergence–divergence (80%; 78,95%; w=0,11). However, it appears that ADHD learners experience more serious problems (Class 3) with visual tracking than learners without ADHD (both eyes: 22,86%; compared to 10,53% (w=0,22); right eye: 11,43% compared to 0% (p=0,05; w=0,34); left eye: 14,29% compared to 0% (p=0,02; w=0,38)). Learners with and without ADHD displayed a practically significant difference with respect to visual perception (d=0,37) and motor coordination (d=0,5) compared to learners without ADHD (who achieved better results). For aim 2 the subjects were divided into three groups. A pre–test–post–test design compiled from an availability sample of three groups (intervention group with ADHD (n=20); control group with ADHD (n=10) and control group without ADHD (n=17)) was used for this part of the study. The intervention group participated in a nine–week (3x/week and for 45 minutes) visualmotor– based intervention programme in which the ocular motor control functions section was applied for about 5 minutes per learner. Forty–seven learners (25 boys and 22 girls) with an average age of 6,95 years (+0,69) constituted the experimental group, while a control group with ADHD with an average age of 7,2 years (+0,79) and a control group without ADHD with an average age of 7,12 years (+0,60) did not receive any intervention and just participated in the pre– and post–test opportunity. A two–way cross–tabulation table was used to determine the changes in ocular motor control functions. These results mainly revealed that practically significant changes occurred in all three groups, be it improvement or deterioration in the various classes of ocular motor control. It appears that as far as horizontal and vertical visual tracking is concerned, and with convergence–divergence, more subjects were moved back from Class 3 (serious cases) to Class 1 (no deficits) and 2 (moderate deficits) in particular than in the other two groups that had received no intervention. Independent t–testing was used to analyse intragroup differences in the visual–motor integration subdivisions, while a covariance analysis (ANCOVA) (corrected for pre–test differences) was used to determine adjusted average post–test difference values. These results revealed that the motor coordination of the intervention group improved more than that of the control group with ADHD (p=0,18). This can lead to the conclusion that the intervention programme did have an effect on this specific skill. Abstract The overall indications of the results are that learners with ADHD have a general tendency to achieve poorer results in ocular motor control tests and with skills involving visual–motor integration, visual perception and motor coordination than learners without ADHD. Although only a minor improvement was identified in the experimental group after participation in the intervention programme, it is recommended with regard to motor coordination in particular that a similar programme be compiled for ADHD learners that focuses more specifically on the ocular motor control needs of each learner, and that it be presented on a more individual basis in order to accomplish greater improvement. / Thesis (M.A. (Kinderkinetics))--North-West University, Potchefstroom Campus, 2012.

The visual system and good ocular motor control play an important role in the effective development of gross motor, sport, fine motor and academic skills (Erhardt et al., 1988:84; Desrocher, 1999:36; Orfield, 2001:114). Various researchers report a link between ocular motor problems and attention–deficit hyperactivity disorder (ADHD) (Cheatum & Hammond, 2000:263; Farrar et al., 2001:441; Gould et al., 2001:633; Armstrong & Munoz, 2003:451; Munoz et al., 2003:510; Borsting et al., 2005:588; Hanisch et al., 2005:671; Mason et al., 2005:1345; Loe et al., 2009:432). A few studies were carried out to analyse the links between ADHD and ocular motor control with regard to matters like visual attention, visual perception and ocular motor control like eye movement outside the normal fixation point, but no studies have been reported on the status of the ocular motor control of South African populations, and the effect of visual–motor intervention on the ocular motor control or visual–motor integration of learners with ADHD. The aim of the study was twofold, namely firstly to determine the ocular motor control functions and status of visual–motor integration of a selected group of 6– tot 8–year–old learners with ADHD in Brakpan, South Africa, while the second aim was to determine whether a visualmotor– based intervention programme can improve the ocular motor control and status of the visual–motor integration of a selected group of 6– to 8–year–old learners with ADHD in Brakpan, South Africa. Statistica for Windows 2010 was used to analyse the data. The Sensory Input Screening measuring instrument and the Quick Neurological Screening Test II (QNST–II) were used to assess the ocular motor control functions (fixation, ocular alignment, visual tracking and convergence–divergence), while the Beery Developmental Test of Visual–Motor Integration (VMI–4de weergawe) was used to determine the status of the learners’ visual–motor integration (VMI), visual perception (VP) and motor coordination (MC). The Disruptive Behaviour Scale, a checklist for ADHD (Bester, 2006), was used as measuring instrument to identify the learners with ADHD. Fifty–six learners (31 boys, 25 girls, with an average age of 7,03 years +0,65) participated in the pre–test and were divided into an ADHD (n=39) and a non–ADHD (n=16) group for aim one. Two–way tables were used to determine the percentage of ocular motor control deficits in the learners with and without ADHD, and an independent t–test was used to analyse the visual–motor integration of these learners. The Pearson Chi–squared test was used to determine the practical significance of differences in VMI and VP (d>0,05). The results of the study reveal that the majority of learners displayed ocular motor control deficits, regardless of whether they were classified with ADHD or not. The biggest percentage of learners fell into Class 2 (moderate deficits), particularly with regard to horizontal (68,57%; 52,63%; w=0,16) and vertical tracking (65,71%; 73,68%), as well as convergence–divergence (80%; 78,95%; w=0,11). However, it appears that ADHD learners experience more serious problems (Class 3) with visual tracking than learners without ADHD (both eyes: 22,86%; compared to 10,53% (w=0,22); right eye: 11,43% compared to 0% (p=0,05; w=0,34); left eye: 14,29% compared to 0% (p=0,02; w=0,38)). Learners with and without ADHD displayed a practically significant difference with respect to visual perception (d=0,37) and motor coordination (d=0,5) compared to learners without ADHD (who achieved better results). For aim 2 the subjects were divided into three groups. A pre–test–post–test design compiled from an availability sample of three groups (intervention group with ADHD (n=20); control group with ADHD (n=10) and control group without ADHD (n=17)) was used for this part of the study. The intervention group participated in a nine–week (3x/week and for 45 minutes) visualmotor– based intervention programme in which the ocular motor control functions section was applied for about 5 minutes per learner. Forty–seven learners (25 boys and 22 girls) with an average age of 6,95 years (+0,69) constituted the experimental group, while a control group with ADHD with an average age of 7,2 years (+0,79) and a control group without ADHD with an average age of 7,12 years (+0,60) did not receive any intervention and just participated in the pre– and post–test opportunity. A two–way cross–tabulation table was used to determine the changes in ocular motor control functions. These results mainly revealed that practically significant changes occurred in all three groups, be it improvement or deterioration in the various classes of ocular motor control. It appears that as far as horizontal and vertical visual tracking is concerned, and with convergence–divergence, more subjects were moved back from Class 3 (serious cases) to Class 1 (no deficits) and 2 (moderate deficits) in particular than in the other two groups that had received no intervention. Independent t–testing was used to analyse intragroup differences in the visual–motor integration subdivisions, while a covariance analysis (ANCOVA) (corrected for pre–test differences) was used to determine adjusted average post–test difference values. These results revealed that the motor coordination of the intervention group improved more than that of the control group with ADHD (p=0,18). This can lead to the conclusion that the intervention programme did have an effect on this specific skill. Abstract The overall indications of the results are that learners with ADHD have a general tendency to achieve poorer results in ocular motor control tests and with skills involving visual–motor integration, visual perception and motor coordination than learners without ADHD. Although only a minor improvement was identified in the experimental group after participation in the intervention programme, it is recommended with regard to motor coordination in particular that a similar programme be compiled for ADHD learners that focuses more specifically on the ocular motor control needs of each learner, and that it be presented on a more individual basis in order to accomplish greater improvement. / Thesis (M.A. (Kinderkinetics))--North-West University, Potchefstroom Campus, 2012.

Experience Mapping based Prediction Control (EMPC) is a new type of controller presented in literature, which is based on the concept of Human Motor Control (HMC). During the developmental phase, called the initial learning phase, the controller records the experience in a knowledge base, through online interactions with the system to be controlled. This knowledge base created using the experience maps is termed as Experience Mapped Knowledge Base (EMK). The controller envisages the development of EMK only through interaction with the system, without the need for knowledge of the detailed plant model. The EMPC controls the system through prediction of actions based on the mapped experiences of EMK. Depending on the nature of control required for the system chosen, various strategies can be used to achieve control using the EMK. The above controller has previously been utilized for motion control applications. In the present work an effort has been made to study the suitability of the EMPC for the voltage regulation of switching converters. The plant chosen for the control study is a discontinuous conduction mode (DCM) buck converter. The parameter to be monitored for the purpose of control is the load voltage. The control input from the EMPC to the converter is a duty ratio value based pulse-width modulated (PWM) signal. Two strategies of control have been proposed: steady state control and transient control. Steady state control action maintains the steady state output voltage at the required value for a given load. The transient control action is used to improve the transient performance of the system. Iterative predictive action and iterative transient actions are used to facilitate convergence of the output voltage to within the required range in presence of non-linearities and uncertainties in the system. Impulse action is introduced to further improve the transient performance of the system. The EMPC is compared a proportional-integral (PI) controller for the given DCM buck system.

The present study is the first to examine the effect of first versus second language (L1 versus L2) speech production on specific temporal parameters of speech in bilingual speakers with neurogenic speech disorders. Three persons with apraxia of speech (AOS), three with phonemic paraphasia (PP) and five normal speaking participants were included as subjects in the study. Subjects were required to read phonemically similar L1 and L2 target utterances in a carrier phrase, five times each, at a normal and fast speaking rate, respectively. This rendered four speaking contexts that included speech production in L1 at either a normal (L1NR) or fast speaking rate (L1FR) and speech production in L2 at either a normal (L2NR) or fast speaking rate (L2FR). Acoustic analysis of on-target productions involved measurement of utterance onset duration, vowel duration, utterance duration and voice onset time. Results revealed that in normal speakers, speech production in L2 results in greater token-to-token variability than in L1. However, token-to-token variability in the experimental subjects did not tend to increase whilst speaking in L2, most probably because these subjects generally decreased their speaking rate in this context, resulting in more consistent production. The subjects with AOS and PP seemed to be influenced by the increased processing demands of speaking in L2 to a greater extent than the normal speakers, in that they more frequently experienced difficulty with durational adjustments (decreasing duration in the fast speaking rate) in L2 than in L1. Furthermore, the subjects with AOS or PP also exhibited a greater extent of durational adjustment in L1 than in L2. The durations of most of the subjects with either AOS or PP tended to differ from those of the normal group to a greater extent in L2FR that was hypothesized to be the most demanding speaking context for these subjects. The longer than normal durations and greater than normal token-to-token variability in the subjects with either AOS or PP imply the presence of a motor control deficit. The extent of the motor control deficit appears to be more severe in AOS than in PP as is evident from the finding that the subjects with AOS generally exhibited longer durations and greater token-to-token variability than the subjects with PP. The pattern of breakdown in respect of different parameters and utterance groups also differed between subjects with AOS and PP. The nature of the disorder in AOS and PP thus appears to be both quantitatively and qualitatively different. Regarding measurement of the different temporal parameters, voice onset time appears to be less subject to the influence of L2 than the other measured temporal parameters. The results of this study imply that bilingual AOS is as much a reality as bilingual aphasia. Furthermore, the results underscore the importance of taking contextual factors, specifically L1 versus L2, into account when compiling assessment and treatment procedures for persons with either AOS or PP, since speech production in L2 appears to be motorically more difficult than in L1 for persons with neurogenic involvement. The significance of the results is discussed with reference to the influence of speech production in L2 on temporal control and the underlying nature of AOS and PP with regard to theories of speech sensorimotor control. Copyright / Dissertation (DPhil (Communication Pathology))--University of Pretoria, 2004. / Speech-Language Pathology and Audiology / unrestricted

Il existe des projections corticospinales (CS) vers les motoneurones (MNs) aussi bien contra- (c) qu’ipsilatérales (i). Les influences CSc sur les MNs du poignet sont connues pour être modulées entre autres par la position du poignet et les afférences cutanées. Pour cette raison, notre objectif était de vérifier si ces caractéristiques sont aussi valides pour les influences CSi. En utilisant la stimulation transcrânienne magnétique au niveau du cortex primaire droit, nous avons tout d’abord comparé les influences CSi sur les MNs des fléchisseurs du poignet à des positions maintenues de flexion et d’extension durant une tâche uni-manuelle ainsi que deux tâches bimanuelles, ceci chez des sujets droitiers (n=23). Nous avons ensuite comparé les influences CSi dans cinq tâches bi-manuelles de tenue d’objet durant lesquelles les sujets avaient à tenir entre leurs mains un bloc à la surface soit lisse, soit rugueuse, dont le poids était supporté ou non, ceci en position de flexion (n=21). Dans une tâche, un poids était ajouté au bloc lisse en condition non supportée pour amplifier les forces de préhension requises. Une modulation positiondépendante était observée au niveau des potentiels évoqués moteurs (iPEM), mais seulement lors de la tâche bi-manuelle quand les deux mains interagissaient via un bloc (p= 0.01). Une modulation basée sur la texture était également présente, quel que soit le support de poids, et le bloc lisse était associé avec des iPEMs plus importants en comparaison avec le bloc rugueux (p= 0.001). Ainsi, les influences CSi sur les MNs n’étaient modulées que lors des tâches bi-manuelles et dépendaient de la manière dont les mains interagissaient. De plus, les afférences cutanées modulaient les influences CSi facilitatrices et pourraient ainsi participer à la prise en main des objets. Il en est conclu que les hémisphères droit et gauche coopèrent durant les tâches bimanuelles impliquant la tenue d’objet entre les mains, avec la participation potentielle de projections mono-, et poly-synaptiques, transcallosales inclues. La possibilité de la contribution de reflexes cutanés et d’étirement (spinaux et transcorticaux) est discutée sur la base de la notion que tout mouvement découle du contrôle indirect, de la « référence » (referent control). Ces résultats pourraient être essentiels à la compréhension du rôle des interactions interhémisphériques chez les sujets sains et cliniques. / There are both contra- (c) and ipsilateral (i) corticospinal (CS) projections to motoneurons (MNs). There is evidence that cCS influences on wrist MNs are modulated by wrist position and cutaneous afferents. Thus, we aimed to test whether these findings are valid for iCS influences as well. Using transcranial magnetic stimulation applied over the right primary motor cortex, we first compared iCS influences on wrist flexor MNs at actively maintained flexion and extension wrist positions in one uni- and two bimanual tasks in right-handed subjects (n=23). We further compared iCS influences in five bimanual holding tasks in which subjects had to hold a smooth or coarse block between their hands, with or without its weight being supported, in flexion position (n=21). In one task, a weight was added to the unsupported smooth block to increase load forces. A position-dependent modulation of the short-latency motor evoked potential (iMEP) was observed, but only in the bimanual task when the two hands interacted through a block (p=0.01). A texture-dependent modulation was present regardless of the weight supported, and the smooth block was associated with larger iMEPs in comparison to the coarse block (p=0.001). Hence, iCS influences on MNs were modulated only in bimanual tasks and depended on how the two hands interacted. Furthermore, cutaneous afferents modulated facilitatory iCS influences and thus may participate to grip forces scaling and maintaining. It is concluded that the left and right cortices cooperate in bimanual tasks involving holding an object between the hands, with possible participation of mono- and poly-synaptic, including transcallosal projections to MNs. The possible involvement of spinal and trans-cortical stretch and cutaneous reflexes in bimanual tasks when holding an object is discussed based on the notion that indirect, referent control underlies motor actions. Results might be essential for the understanding of the role of intercortical interaction in healthy and neurological subjects.

No description available.

No description available.