Cette thèse est consacrée à la modélisation d'une structure constituée de l'assemblage de deux solides Ω+ et Ω− à l'aide d'une couche mince (d'épaisseur d'ordre ε) très rigide (d'ordre 1/ε), où ε est un petit paramètre. Différentes situations et considérations sont prises en compte. Dans un premier temps, on se place dans le cadre de l'élasticité linéaire. Une analyse asymptotique formelle conduit à un problème posé sur Ω+UΩ-US où S est l'intersection des frontières . Nous nous intéressons dans cette partie aux deux aspects suivants : - Prise en compte de la géométrie et de la rigidité de la couche intermédiaire : résultats de convergence faible et forte pour des modèles de plaques et de coques ; - Proposition de méthodes de résolution numérique par décomposition de domaine ou avec pénalisation. Nous proposons ensuite une modélisation dans un cadre plus général et obtenons dans le cadre de la Γ-convergence, un modèle en élasticité linéaire non isotrope et un modèle en élasticité non linéaire. Lorsque le matériau dans la couche rigide présente des transitions de phase solide/solide, sa densité d'énergie g possède plusieurs puits de potentiel rendant compte de microstructures. Pour modéliser ces microstructures, il convient de réécrire l'énergie dans la couche en terme de mesures de Young. L'énergie de la structure est alors donnée par une bifonctionnelle ayant pour argument un couple déplacement-mesure de Young. Une des deux fonctions marginales de la fonctionnelle limite nous redonne l'énergie (classique) du modèle limite obtenu précédemment par Γ-convergence . Nous pouvons également réécrire l'énergie de toute la structure en terme de mesures de Young. Nous montrons alors comment les solutions du problème formulé en terme de mesures de Young donnent une description microscopique des solutions classiques. Enfin, lorsque la couche mince a un comportement plastique, des difficultés liées à la croissance linéaire de l'énergie de densité g apparaissent. En s'inspirant des méthodes de régularisation de Norton-Hoff, nous étudions le cas où g est à croissance d'ordre p, 1< p <2, la densité d'énergie f dans le reste de la structure étant à croissance d'ordre 2. Nous obtenons un premier modèle limite lorsque ε tend vers 0. Nous étudions ensuite la Γ-convergence de la fonctionnelle limite obtenue lorsque p tend vers 1. Mots clés : élasticité, multi-matériau, Γ-convergence, analyse asymptotique, mesures de Young.

Published in Lietuvos Matematikos Rinkinys, Vol. 46, No. 3, pp. 332–350, July–September, 2006.

Video game journalism has been accused for lack in journalistic legitimacy for decades. The historical relation between video game journalists and video game publishers has always been problematic from an objective point of view, as publishers have the power to govern and dictate journalistic coverage by withdrawing financial funding and review material. This has consequently lead to lack in journalistic legitimacy when it comes to video game coverage. However, as the grass roots media movement gained popularity and attention in the mid 2000s, a new more direct and personal way of coverage became evident. Nowadays, grass roots media producers operate within the same field of practice as traditional journalists and the difference between entertainment and journalism has become harder than ever to distinguish. The aim of this master thesis is to discover if grass roots media is more critical than traditional video game journalism regarding industry coverage. The study combines Communication Power theory, Web 2.0 and Convergence Culture, as well as Alternative Media and Participatory Journalistic theory, to create an interdisciplinary theoretical framework. The theoretical framework also guides our choice in methodology as a grounded theory study, where the aim of analysis is to present or discover a new theory or present propositions grounded in our analysis. To reach this methodological goal, 10 different grass roots media producers were interviewed at 6 different occasions. The interviewees were asked about their opinions regarding grass roots media production, their own contribution, as well how they identified journalistic coverage. It was discovered that the grass roots media producers were not more critical than traditional video game journalists. This was because grass roots media producers operate under the rules of entertainment production. It was discovered that if grass roots media producers break out of the normative rules of entertainment production, they would either loose their autonomous freedom or funding, resulting in a catch-22 situation. Furthermore, it was found that grass roots media producers did not identify themselves as journalists; rather they identified themselves as game critics or reviewers. Thus, a video game journalist is categorised as an individual that report writes or edits video game news as an occupation, with formal journalistic training. However, since neither grass roots media producers nor industry veterans in general have journalistic training, it is still unclear who is a video game journalist. Lastly, we found that grass roots media producers have little possibility to influence traditional video game journalism. The only way to increase the status of journalistic legitimacy is by encouraging journalism itself, to engage in critical media coverage. As there is a public demand for industry coverage, and journalistic legitimacy is grounded on the normative democratic self-descriptions of the profession, video game journalism needs to move beyond entertainment and engage in democratically, constructive and critical coverage.

Various researchers have found that visual problems can contribute to clumsiness in children with DCD. One cause of motor development shortfalls that contribute to a DCD classification seems to be weak eye muscle functions. The visual system as well as well-developed eye muscle functions, play an important role in die development of balance, spatial orientation, body awareness and coordination (hand-eye, foot-eye, hand-foot-eye coordination). It also emerges from the literature that children with DCD do not usually outgrow their problems, although controversy still surrounds this aspect. The aim of this study was twofold. The first aim was to determine, as established by eye muscle functions, what the nature and scope of visual problems are, that is associated with DCD in 7 and 8 year-old children in Potchefstroom. The second aim was to determine whether 7 and 8 year-old Potchefstroom children will outgrow their DCD status without any motor intervention, and what the relationship between vision and the lasting effects of DCD status is. Thirty-two children (20 boys and 12 girls) with an average age of 95.66 months engaged in the study. During a follow-up study after a year of baseline testing at 83.33 months, the researcher wanted to determine whether the subjects diagnosed with DCD had possibly outgrown their DCD status. The Movement Assessment Battery for Children (MABC) (Henderson & Sugden, 1992) was applied for this purpose. The Sensory Input Screening Test (Pyfer, 1987), and the "Quick Neurological Screening Test" (QNST) (Mutti et al., 1998) test batteries were employed to determine the visual status of the children. The "Statistica for Windows 2008" computer software was used to analyse the data. Correlation coefficients as well as two-way variance tables were used for objective one to analyse the relationship between DCD and vision. The results confirmed correlations between DCD and eye muscle functions. Relationships were found between different eye muscle functions (fixation, visual pursuit, left and right eye, ocular alignment right eye) and the MABC total. Significant correlations, with small practical significance (p 10.2) was found between fine motor skills and fixation with both eyes, and with the left eye separately, visual pursuit with the right eye, as well as ocular alignment with the right eye, while a correlation with moderate practical significance (p 10.5) was found with fixtion with the right eye. All six eye muscle functions showed significant correlations with small practical significance (p 10.2) with ball skills. Static and dynamic balance also showed significant correlations with small practical significance (p 10.2) with fixation with both eyes, the left and right eye separately as well as with ocular alignment with the right eye. The results further indicated that in most cases where children have been diagnosed with serious DCD, they were classified in Class 3 (where more than three visual deviations occurred in the subject) regarding their vision. These percentages varied from 36.67% to 83.33%, with the highest percentage problems found in visual pursuit with the right eye. For objective 2, a dependent t-test was employed to determine the state of the children's DCD after a year has lapsed since diagnosis. The differences between the testing showed that most of the children have not outgrown their DCD status, but that the motor performance of a majority of the children has deteriorated over a period of one year (p 10.00). Furthermore, the percentage visual problems in the group with sustained DCD ranged from 71,87% - 100% (visual pursuit, fixation and ocular alignment), with the most visual problems found in fixation and visual pursuit skills. It can be concluded from the results that a significant relationship exists between DCD and a variety of visual functions, as determined by the different eye muscle functions. This evidence also indicated that most children will not outgrow their DCD status without any motor intervention programme. Intervention of children who are diagnosed with DCD should therefor include visual therapy. / Thesis (M.A. (Human Movement Science))--North-West University, Potchefstroom Campus, 2009.

Various researchers have found that visual problems can contribute to clumsiness in children with DCD. One cause of motor development shortfalls that contribute to a DCD classification seems to be weak eye muscle functions. The visual system as well as well-developed eye muscle functions, play an important role in die development of balance, spatial orientation, body awareness and coordination (hand-eye, foot-eye, hand-foot-eye coordination). It also emerges from the literature that children with DCD do not usually outgrow their problems, although controversy still surrounds this aspect. The aim of this study was twofold. The first aim was to determine, as established by eye muscle functions, what the nature and scope of visual problems are, that is associated with DCD in 7 and 8 year-old children in Potchefstroom. The second aim was to determine whether 7 and 8 year-old Potchefstroom children will outgrow their DCD status without any motor intervention, and what the relationship between vision and the lasting effects of DCD status is. Thirty-two children (20 boys and 12 girls) with an average age of 95.66 months engaged in the study. During a follow-up study after a year of baseline testing at 83.33 months, the researcher wanted to determine whether the subjects diagnosed with DCD had possibly outgrown their DCD status. The Movement Assessment Battery for Children (MABC) (Henderson & Sugden, 1992) was applied for this purpose. The Sensory Input Screening Test (Pyfer, 1987), and the "Quick Neurological Screening Test" (QNST) (Mutti et al., 1998) test batteries were employed to determine the visual status of the children. The "Statistica for Windows 2008" computer software was used to analyse the data. Correlation coefficients as well as two-way variance tables were used for objective one to analyse the relationship between DCD and vision. The results confirmed correlations between DCD and eye muscle functions. Relationships were found between different eye muscle functions (fixation, visual pursuit, left and right eye, ocular alignment right eye) and the MABC total. Significant correlations, with small practical significance (p 10.2) was found between fine motor skills and fixation with both eyes, and with the left eye separately, visual pursuit with the right eye, as well as ocular alignment with the right eye, while a correlation with moderate practical significance (p 10.5) was found with fixtion with the right eye. All six eye muscle functions showed significant correlations with small practical significance (p 10.2) with ball skills. Static and dynamic balance also showed significant correlations with small practical significance (p 10.2) with fixation with both eyes, the left and right eye separately as well as with ocular alignment with the right eye. The results further indicated that in most cases where children have been diagnosed with serious DCD, they were classified in Class 3 (where more than three visual deviations occurred in the subject) regarding their vision. These percentages varied from 36.67% to 83.33%, with the highest percentage problems found in visual pursuit with the right eye. For objective 2, a dependent t-test was employed to determine the state of the children's DCD after a year has lapsed since diagnosis. The differences between the testing showed that most of the children have not outgrown their DCD status, but that the motor performance of a majority of the children has deteriorated over a period of one year (p 10.00). Furthermore, the percentage visual problems in the group with sustained DCD ranged from 71,87% - 100% (visual pursuit, fixation and ocular alignment), with the most visual problems found in fixation and visual pursuit skills. It can be concluded from the results that a significant relationship exists between DCD and a variety of visual functions, as determined by the different eye muscle functions. This evidence also indicated that most children will not outgrow their DCD status without any motor intervention programme. Intervention of children who are diagnosed with DCD should therefor include visual therapy. / Thesis (M.A. (Human Movement Science))--North-West University, Potchefstroom Campus, 2009.

This paper adopts a spatial econometric perspective to analyse regional convergence of per capita income in Europe in 1995 to 2000 and, moreover, relaxes the assumption of a single steady-state growth path which appears to be out of tune with reality of empirical dynamics. The two-club spatial error convergence model with groupwise heteroskedasticity is found to be most appropriate for the data at hand. Two empirical key findings are worthwhile to note. The first is that the data provide much support for unconditional ß-convergence in Europe. The second is that the usual convergence conclusions hold. But they do so for reasons that are not revealed by the classical test equation that is typical in mainstream economics literature. (authors' abstract)

The effect of the element length is examined in modelling crack growth in fatigue loading of an adhesive joint. This is done for a cohesive element using an expression for the damage evolution developed at the University of Skövde which is implemented using the UMAT subroutine in the FE-solver Abaqus. These analyses are done for pure mode I loading by analysing a DCB-specimen loaded by a pure moment. An expression is developed in which the critical element length is dependent on the geometry of the specimen (in the form of the wave number of the adhesive joint), the element length, the material properties of the adhesive (in form of the material parameters , , ), the load applied (in form of the stress in the crack tip), the time step used in the analysis and the crack growth rate. It is shown that the results converge by decreasing the element length and the time step used. Therefore an expression for the crack growth rate as a function of the remaining parameters can be determined. Another expression is thereafter developed for the element length needed in order to get a crack growth rate within a certain range of the critical element length. The results show a regular pattern but are not monotone. Therefor two different definitions of the critical element length are tested, either by defining the critical element length as the point where the error is greater than an arbitrary boundary of 1 % of a converged result or where a least square approximation of the error is within 1 % of the converged results. The first method shows a highly irregular result which makes it difficult to develop an expression out of these results. The second method on the other hand gives results that are predictable enough to develop a function out of them. This is done using a regression analysis with all parameters of a third order expression in order to get an expression.

Phonetic accommodation is the process whereby speakers in an interaction modify their speech in response to their interlocutor. The social-psychological theory of Communication Accommodation Theory (Giles 1973) predicts that speakers will converge towards (become more similar to) their interlocutors in order to decrease social distance, whereas they will diverge from (become less similar to) their interlocutors to accentuate distinctiveness or show disdain. Previous studies have found that phonetic accommodation is affected by many social, situational and linguistic factors (Abrego-Collier et al. 2011; Black 2012; Babel 2009, 2010, 2012; Babel et al. 2012; Kim, Horton & Bradlow 2011; Nielsen 2011; Pardo et al. 2012). With respect to accommodation across dialects, a handful of studies have suggested that the perceptual salience of the various differences between two dialects might affect the pattern; however, these studies make conflicting predictions. Trudgill (1986) predicts that speakers will converge more towards the more salient dialectal differences, while Kim et al. (2011) and Babel (2009, 2010) suggest the opposite: that speakers will converge on the less salient differences. This thesis investigates how the perceptual salience of 6 differences between Buenos Aires Spanish and Madrid Spanish affect the pattern of phonetic accommodation in conversation. The results are considered both in terms of the magnitude of the changes that the participants make as well as the direction of the change (convergence or divergence). The results show that perceptual salience has a significant effect on the magnitude of the change, with all participants making greater changes as perceptual salience increases. On the other hand, perceptual salience was found not to have a consistent effect for all speakers on the likelihood of converging or diverging on the dialectal differences. I argue that the lack of consistent effect of salience on the direction of the change stems from individual differences in motivation to take on the opposing dialect norms and issues of personal identity, whereas the very consistent effect of salience on the magnitude of the change suggests that there is something more basic or systematic about how salience interacts with the extent to which speakers accommodate.

The objective of this dissertation is to apply radiogenic isotopes extracted from marine sediments to investigate aspects of global climate change over the past 25 kyr, especially ocean and atmospheric circulation, continental aridity, and hydrology. By focusing on the geochemical records from marine sediments and authigenic precipitates preserved in these sediments, I aim to better understand climate forcing and feedback mechanisms, which are critical to models of climate change. Firstly, I have investigated the dynamics of the Intertropical Convergence Zone (ITCZ) over the past 25 kyr in the eastern equatorial Pacific by fingerprinting dust provenance using radiogenic isotopes (Nd, Sr, Pb) and trace elements (Fe, Si, Ba) in the detrital fraction of marine sediments along a transect across the equator at 110ºW. Results from this study suggest no glacial-Holocene difference in the mean position of the ITCZ, but a more northerly, possibly stronger, deglacial ITCZ. Secondly, I have applied Nd isotope ratios from authigenic precipitates extracted from marine sediments and those from fish debris to trace past intermediate water circulation changes on glacial-interglacial and millennial timescales. The authigenic Nd isotope record from the Florida Straits suggests a reduced circulation of Antarctic Intermediate Water (AAIW) into the tropical North Atlantic during the Younger Dryas (YD) and Heinrich 1 (H1) events, associated with a significant reduction in AMOC. However, in the Southern Caribbean, apparent deviations in the Nd isotopic compositions between the acid-reductive leachate and the fish debris suggest that the leachate method is not reliable at this location and that it needs to be tested in more detail in various oceanic settings. In the Southern Caribbean, the fish debris Nd isotope results suggest a two-step recovery of the upper North Atlantic Deep Water during the last deglaciation. Comparing our new fish debris Nd isotope data to authigenic Nd isotope data for sediments from the Florida Straits and the Demarara Rise, we propose that glacial and deglacial AAIW does not penetrate beyond the lower depth limit of modern AAIW in the tropical North Atlantic. Both studies suggest a tight connection between Atlantic intermediate water circulation variability and high-latitude North Atlantic climate change.

As the capabilities of autonomous vehicles increase, their use in situations that are dangerous or dull for humans is becoming more popular. Autonomous systems are currently being used in several military and civilian domains, including search and rescue operations, disaster relief coordination, infrastructure inspection and surveillance missions. In order to perform high level mission autonomy tasks, a method is required for the vehicle to localize itself, as well as generate a map of the environment. Algorithms which allow the vehicle to concurrently localize and create a map of its surroundings are known as solutions to the Simultaneous Localization and Mapping (SLAM) problem. Certain high level tasks, such as drivability analysis and obstacle avoidance, benefit from the use of a dense map of the environment, and are typically generated with the use of point cloud data. The point cloud data is incorporated into SLAM algorithms with scan registration techniques, which determine the relative transformation between two sufficiently overlapping point clouds. The Normal Distributions Transform (NDT) algorithm is a promising method for scan registration, however many issues with the NDT approach exist, including a poor convergence basin, discontinuities in the NDT cost function, and unreliable pose estimation in sparse, outdoor environments. This thesis presents methods to overcome the shortcomings of the NDT algorithm, in both 2D and 3D scenarios. To improve the convergence basin of NDT for 2D scan registration, the Multi-Scale k-Means NDT (MSKM-NDT) algorithm is presented, which divides a 2D point cloud using k-means clustering and performs the scan registration optimization over multiple scales of clustering. The k-means clustering approach generates fewer Gaussian distributions when compared to the standard NDT algorithm, allowing for evaluation of the cost function across all Gaussian clusters. Cost evaluation across all the clusters guarantees that the optimization will converge, as it resolves the issue of discontinuities in the cost function found in the standard NDT algorithm. Experiments demonstrate that the MSKM-NDT approach can be used to register partially overlapping scans with large initial transformation error, and that the convergence basin of MSKM-NDT is superior to NDT for the same test data. As k-means clustering does not scale well to 3D, the Segmented Greedy Cluster NDT (SGC-NDT) method is proposed as an alternative approach to improve and guarantee convergence using 3D point clouds that contain points corresponding to the ground of the environment. The SGC-NDT algorithm segments the ground points using a Gaussian Process (GP) regression model and performs clustering of the non ground points using a greedy method. The greedy clustering extracts natural features in the environment and generates Gaussian clusters to be used within the NDT framework for scan registration. Segmentation of the ground plane and generation of the Gaussian distributions using natural features results in fewer Gaussian distributions when compared to the standard NDT algorithm. Similar to MSKM-NDT, the cost function can be evaluated across all the clusters in the scan, resulting in a smooth and continuous cost function that guarantees convergence of the optimization. Experiments demonstrate that the SGC-NDT algorithm results in scan registrations with higher accuracy and better convergence properties than other state-of-the-art methods for both urban and forested environments.