Dissertations / Theses on the topic 'Action Observation System'

L’imitation volontaire est établie comme l’un des modes principaux d’acquisition des habiletés motrices. Il existe également une autre forme d’imitation, automatique et involontaire, étudiée initialement en psychologie sociale du fait de son interaction étroite avec les comportements pro-sociaux. Récemment, et sous l’influence de travaux des années 1990 mettant en lumière des substrats neuronaux communs à l’observation et à l’exécution du mouvement, les recherches scientifiques se sont concentrées sur cette notion d’imitation automatique et ont investigué, via différents paradigmes expérimentaux, les effets de facilitation et d’interférence entre mouvements observés et exécutés. Le travail réalisé dans le cadre de cette thèse vise à améliorer notre compréhension des mécanismes de contagion motrice et à identifier leurs applications possibles au réentraînement moteur. Dans une première étude, nous avons évalué l’impact de l’observation de mouvements de déséquilibre sur le balancement postural d’observateurs jeunes (24,5 ± 5 ans), sans troubles posturaux. Le contrôle de l’équilibre orthostatique fait principalement intervenir des structures sous-corticales pour le maintien du tonus postural et l’intégration multisensorielle. Ces substrats neuronaux seraient, de la même manière que les fonctions végétatives indépendantes du contrôle volontaire, plus facilement contaminés par les mouvements observés. Cependant, l’observation d’un déséquilibre sollicite également des mécanismes de régulation posturale, qui restreignent le balancement de l’observateur et se surajoutent à des processus inhibiteurs prévenant l’imitation compulsive des mouvements observés. Par conséquent, ce paradigme expérimental nous a permis de tester les limites des effets de contagion à partir d’une situation où les processus inhibiteurs et régulateurs de la posture étaient fortement sollicités. Cette étude nous a conduits à mettre en évidence une contamination du balancement postural des sujets par le déséquilibre observé, ce qui a confirmé l’importance et la prédominance des processus d’imitation. Ce résultat soulève des questions importantes en termes d’applications au réentraînement moteur chez les patients souffrant de troubles posturaux, en particulier chez les personnes âgées qui présentent une altération de leurs fonctions de stabilisation. En effet, si l’observation d’un déséquilibre conduit à une réaction de contagion motrice, il est vraisemblable qu’elle sollicite également des fonctions inhibitrices et régulatrices permettant la stabilisation de l’observateur. La visualisation répétée d’un déséquilibre peut-elle alors conduire à une amélioration de la stabilisation chez les personnes à risque ? Pour étudier cette question, il serait nécessaire de répéter ce protocole chez le public cible - les réponses pouvant être modulées par l’âge et les aptitudes motrices des personnes. Notre seconde étude visait à évaluer l’impact du répertoire moteur sur les réactions de contagion motrice. S’il est admis que le système moteur (contraintes biomécaniques, niveau d’expertise) affecte les processus perceptifs, son effet sur les réactions d’imitation automatique a été peu étudié. Nous avons analysé les réactions posturales d’observateurs jeunes (24,2 ± 3,7 ans), sains, face à des séquences de déséquilibre antéro-postérieur et médio-latéral. Les stratégies d’équilibration posturale sont associées à des contraintes différentes selon ces deux axes, avec une symétrie médio-latérale et une asymétrie antéropostérieure – asymétrie résultant d’une position du centre de masse en avant de l’articulation de la cheville, qui induit une sollicitation accrue des muscles du plan postérieur pour la stabilisation posturale. Un impact du système moteur sur le processus de contagion serait donc susceptible de se traduire par des réactions posturales différentes dans nos deux conditions d’observation. etc
Voluntary imitation is known as a major means of acquisition of motor skills. Besides, another form of imitation, automatic and involuntary, was initially more extensively studied in social psychology, perhaps because of its close interaction with prosocial behaviors. Recently, there was a renewal of interest in automatic imitation, following research works of the 1990s that highlighted common neural substrates for movement observation and execution. In this context, scientific studies started, through various experimental paradigms, to investigate facilitation and interference effects between observed and executed movements. Research work presented in this thesis aims to improve our understanding of the mechanisms involved in motor contagion and to identify their possible application to motor retraining. For this purpose, we evaluated, in our first study, the impact of observation of postural imbalance on body sway of young (24.5 ± 5 years), healthy observers. Postural control mainly relies on subcortical structures for maintaining postural tonus and ensuring multisensory integration. Similarly to vegetative functions that are independent of voluntary control, these neural substrates would be more easily contaminated by observed movements. However in response to observed imbalance, postural regulation mechanisms, superimposed to inhibitory processes that prevent compulsive imitation, restrain observers’ disequilibrium. Therefore, this experimental paradigm enabled us to test the limits of contagion mechanisms in a situation highly soliciting inhibitory and regulation processes. Our results led us to highlight a contagion effect of observed imbalance on subjects’ postural sway, which confirmed the importance of imitation processes. These results raise an important question in terms of applications for movement retraining in patients with postural disorders, more specifically in elderly patients with impaired stabilization functions. In effect, if observation of postural imbalance leads to a motor contagion response, it is also likely to solicit regulatory and inhibitory functions for observers’ postural stabilization. Thus, could repeated observation of such disequilibrium movements lead to an improvement of stabilization functions for subjects with postural deficits? To investigate this question, it will be necessary to repeat this protocol with the target population, since observers’ response is likely to vary with age and motor competences. To complete this work, we conducted a second study to assess the impact of the motor repertoire on motor contagion responses. Although it is widely accepted that the motor system (biomechanical constraints, level of expertise) affects perceptual processes, its effect on imitative responses has been little studied. We analyzed postural reactions of young (24.2 ± 3.7 years), healthy observers when presented with sequences of anteroposterior and medio-lateral imbalance. Postural equilibration strategies are associated with different constraints along these two axes, with a medio-lateral symmetry and an anteroposterior asymmetry – this latter asymmetry results from a location of the center of mass ahead of the ankle joint, which induces an increased solicitation of muscles from the posterior plane for stabilization. An impact of the motor system on the contagion process could therefore appear in the form of different postural responses in our two observation conditions. Our results indicated a greater contagion effect during observation of anteroposterior compared to medio-lateral imbalance. Postural contagion is therefore conditioned by observers’ equilibration strategy. In our third study, we considered using this contagion effect for perceptual training aimed at the maintenance and improvement of elderly subjects’ motor performances. The issue of an observational training device is especially relevant when considering people for whom physical exercise is limited due to fatigue or pain.etc

A key factor to the Scottish Governments' public policy and public service reconfiguration is collaborative working between service providers and service users in a framework of co-production. A second key factor in this reform is a place-based approach. Despite this rhetoric of co-production of health services having been used for some time in health policy, and considering the numerous interpretations of the meaning of both co–production and 'place' in the academic and professional literature, how rural dwellers experience rurality in terms of places and space, and how this may in turn affect health and interactions with co-production, remains underrepresented in health policy planning. In light of changes in health service provision, rural health care poses itself as a potentially emotive and sometimes volatile topic. A co-productive approach may encourage understanding, acceptance and better usage of health services and neighbourhood resources, by the residents registered as patients with local medical practices. This doctoral research study considered the use of participatory mapping techniques to generate, gather and capture the local voice of residents from two rural Scottish communities, regarding the self-perception of their health in relation to the place they call home. Through a participatory action research approach, using iterative co-design, residents were asked how their environment impacted on their health, and in particular their cardiovascular health. Qualitative data were collected through participatory mapping techniques and co- analysed using a thematic analysis process. The application of the concept of therapeutic landscapes revealed the importance of the 'sense of place' and its impact on health, along with the physical, social and cultural environmental aspects traditionally considered in public health disciplines. Results were digitised using geographic information systems (GIS) to illustrate the interactions between place, people and health, through a relational lens. This research demonstrates a working example of how, drawing from the discipline of health geography, a place based approach can make an important contribution to rural health service co- planning within a co-production framework.

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The Mental Simulation theory suggests activation of the motor network during imagery and execution of movements, similarly to the activation during observation and execution of actions, which is mediated by the Mirror Neuron System. This activation can be measured using eletroencefalography register of Mu rhythm suppression. It is propose that motor network activation and therefore increase of cortical excitability at primary motor cortex and Mu dessynchronization are due to premotor Miror-Neuron System inputs. Transcranial direct current stimulation is a neuromodulation technique that induce facilitation and inhibition of neural firing leading to enhance or decrease in cortical excitability, respectively. Thus, we propose to evaluate the polarity dependent effects of this technique in the Mu rhythm during biological and non-biological movements observation and imagery tasks. Therefore we applied anodal, cathodal and sham stimulation in 21 male subjects (mean age 23.8+3,06), over left primary motor cortex (2mA for 20min) and immediately after we registered the electroencephalography considering the electrodes C3, C4 and surrounding C3 and C4 and Cz. Analyses of C3 and C4 showed significant effects according to Movement (p=0.005), and also for the interactions between type of stimulation and hemisphere (p=0.04) and type of stimulation, movement and hemisphere (p=0.02). Surrounding electrodes analyses revealed significant effect for the interaction between stimulation type, task condition and movement type (p=0.03). Thus, the main findings of this study were i. Mu suppression for biological movement (in both imagery and observation) of the hand region in the contralateral hemisphere after sham stimulation, ii. reverse effect for the surrounding electrodes during imagery condition and iii. polarity-dependent neuromodulation of the Mu rhythm. The results are discussed considering focal ERD/ surrounding ERS according to the type of task. We concluded that there are contralateral focal Mu dessynchronization during observation and imagery of biological movements together with syncronizarion of the motor areas not involved in the task only for the imagery condition and that transcranial direct current stimulation has a significant effect under the entire electrode and according to the applied polarity. The use of transcranial direct current stimulation followed by observation and imagery tasks might be an interesting intervention strategy for disturbances involving motor ability impairment as well as deficits related to imitation and comprehension of other s actions.
A teoria de simulação mental sugere ativação da rede neural motora durante mentalização e execução de movimentos, de maneira análoga à ativação em observação e execução de ações, o que é mediado pelo Sistema de Neurônios-Espelho. Esta ativação pode ser mensurada por supressão do ritmo Mu registrado por eletroencefalografia. É proposto que a ativação de áreas motoras e, portanto, o aumento de excitabilidade cortical em cortex motor primário e a dessincronização do ritmo Mu ocorram em consequência de insumo proveniente do Sistema Neurônios-Espelho pré-motor. A estimulação transcraniana por corrente contínua consiste numa técnica de neuromodulação por facilitação e inibição de disparo neuronal levando a aumento e redução de excitabilidade cortical, respectivamente. Assim, foi proposto avaliar os efeitos polaridade dependentes desta técnica sobre ritmo Mu durante tarefas de observação e mentalização de movimentos biológicos e não biológicos. Para tal, aplicamos estimulação anódica, catódica e placebo em 21 homens destros (idade média de 23.8+3,06), sobre córtex motor primário esquerdo (2mA por 20min) e, em seguida foi feito o registro eletroencefalográfico considerando os eletrodos C3, C4 e entorno de C3 e C4 e Cz. A análise de C3 e C4 apresentou efeitos significativos quanto ao tipo de Movimento (p=0.005) e ainda quanto as interações entre tipo de estimulação e hemisfério (p=0.04) e tipo de estimulação, de movimento e hemisfério (p=0.02). A análise dos eletrodos do entorno revelou efeito significativo para a interação entre tipo de estimulação, condição da tarefa e tipo de movimento (p=0.03). Assim, os principais achados do estudo foram i. supressão de Mu para movimento biológico (em mentalização e observação) da região da mão em hemisfério contralateral após estimulação placebo, ii. efeitos inversos para eletrodos de entorno em condição de mentalização e iii. neuromodulação polaridade dependente de ritmo Mu. Os resultados de oscilação de Mu são discutidos considerando ERD focal/ ERS entorno de acordo com o tipo de tarefa. Concluímos que há dessincronização contralateral focal de Mu durante observação e mentalização de movimentos biológicos, acompanhada por sincronização de áreas motoras não envolvidas na tarefa apenas na condição de mentalização e que a estimulação transcraniana por corrente contínua tem efeito sob toda a superfície do eletrodo e difere de acordo com a polaridade aplicada. O uso da estimulação transcraniana por corrente contínua combinada com tarefas de observação e mentalização pode conferir uma estratégia interessante de intervenção em distúrbios envolvendo comprometimento das habilidades motoras bem como comprometimento de habilidades de imitação e compreensão das ações do outro.

L'obiettivo principale del lavoro è stato di valutare il ruolo della neurostimolazione e della multimodalità (intesa come la presentazione visiva di un modello che esegue un movimento assieme a una musica sincrona) nell’apprendimento motorio, indagando sia gli effetti sugli adulti sani sia su pazienti affetti da Morbo di Parkinson (MP). Per raggiungere tale obiettivo, sono state condotte tre ricerche sperimentali e longitudinali, utilizzando diversi strumenti, come tDCS, biofeedback e KinectTM. Partendo da una sistematica revisione della letteratura nel campo della riabilitazione neuromotoria, sono state identificate tre forme di trattamento che sembrano efficaci contro i sintomi motori del MP. Tuttavia, pur riconoscendo la loro efficacia, non sono mai stati combinati nella pratica riabilitativa: l’Action Observation Learning (basato sulla teoria del sistema dei neuroni specchio), la neurostimolazione anodica non-invasiva sulla zona motoria primaria e l'uso della musica. I risultati dimostrano un chiaro sostegno della multimodalità e della neuro stimolazione nella fase di encoding e un loro supporto nel migliorare le funzioni motorie, anche a distanza di un mese. Questo lavoro offre nuove indicazioni per lo sviluppo di approcci innovativi ed efficaci nel campo dell’apprendimento motorio.
The main objective was to assess the role of neurostimulation and multimodality (namely the presentation of a visual model together with a synchronized musical track) in motor learning, by considering both healthy adults and Parkinsonian patients (PD). In order to achieve this goal, three experimental and longitudinal studies were carried out, using different tools such as tDCS, biofeedback and KinectTM. Starting with a systematic review, three innovative approaches which seem to be effective in treating the motor symptoms of PD, were identified. However, while recognizing the effectiveness of these three promising approaches, they have never been combined: Action Observation Learning (based on the theory of mirror neuron system), the non-invasive anodal neurostimulation on the primary motor area and the use of music. The results showed a clear support of multimodality and neurostimulation during the encoding phase and in improving motor functions, even after one month. This work provides new suggestions for innovative and effective treatments in motor learning field.

Cette thèse s'intéresse au diagnostic et à l'observation de systèmes linéaires à commutations et à l'application au convertisseur multicellulaire série. L'objectif est de proposer des solutions pour des sous-systèmes non-observables au sens classique et dont des fautes continues ou discrètes peuvent être présentes. Après la présentation d'un état de l'art sur les techniques d'observation et de diagnostic pourles systèmes à commutations, le mémoire est scindé en deux parties. La première partie propose, d'une part, une stratégie d'estimation des états discret et continu d'un système linéaire à commutation soumis à une entrée inconnue. Un observateur hybride basé sur la théorie des modes glissants d'ordre supérieur est développé. D'autre part, deux procédures de diagnostic sont présentées. La première combine un observateur hybride et un diagnostiqueur pour détecter une faute continue. Pour la seconde, un diagnostic actif est défini sur la base de la théorie du test afin de détecter et d'isoler une faute discrète. Dans la seconde partie de ce mémoire, les étapes de la réalisation d'un convertisseur multicellulaire sont détaillées. Ensuite, un chapitre est dédié à la validation des approches théoriques d'observation et de diagnostic sur le convertisseur à trois cellules. Un observateur est synthétisé afin d'estimer les tensions des capacités. Les deux procédures de diagnostic sont appliquées pour la détection d'une variation des valeurs des capacités et le diagnostic de cellules bloquées. Enfin, une commande binaire pour le convertisseur est proposée. L'application de cette stratégie permettra, par la suite, la commande tolérante aux fautes du convertisseur.

Das Gebiet der bodengebundenen Gamma-Astronomie bietet Zugang zu Photonen im TeV-Energiebereich und hat sich in den letzten Jahrzehnten vor allem durch den Erfolg der abbildenden atmosphärischen Cherenkov-Technik profiliert. In dieser Arbeit werden zwei dieser Cherenkov-Teleskop-Systeme, VERITAS und das zukünftige CTA, mit Hilfe von Monte-Carlo-Simulationen in Hinblick auf deren Sensitivität auf hochenergetische Gammastrahlung (E > 50 GeV) untersucht. Besonderes Augenmerk wird hierbei auf die Beobachtungsmöglichkeit mit CTA unter Mondlicht gelegt. Es wird gezeigt, dass dadurch eine Beobachtungszeitverlängerung um etwa 30% ohne signifikante Sensitivitätsverluste erreicht werden kann, was besonders wichtig für zeitlich variable Quellen ist. Eine dieser variablen Quellklassen sind aktive Galaxienkerne, welche zur Zeit etwa ein Drittel der bekannten hochenergetischen Gammastrahlungsquellen repräsentieren. Die meisten davon sind Blazare, deren Emission durch nicht-thermische Strahlung aus gebündelten Strömen von Materie und Energie (sogenannten Jets) dominiert wird. Diese Jets breiten sich mit annähernd Lichtgeschwindigkeit aus und sind in Sichtlinie des Betrachters ausgerichtet. Der Blazar B2 1215+30 wurde zwischen 2008 und 2012 mit VERITAS fast 100 Stunden beobachtet. Die Datenanalyse, welche in dieser Arbeit präsentiert wird, weist die Quelle mit einer Signifikanz von neun sigma nach und offenbart Langzeitvariabilität mit einem hellen Flusszustand im Jahr 2011. Multi-Wellenlängen-Daten werden verwendet um die spektrale Energieverteilung von B2 1215+30 zu konstruieren, welche gut mit einem leptonischen Ein-Zonen-Modell beschrieben werden kann. Das verwendete Modell wird im Detail vorgestellt und mögliche Einschränkungen an den Modellparameterraum untersucht. Die Ergebnisse der Modellierung von B2 1215+30 werden diskutiert und in Zusammenhang mit anderen bekannten hochenergetischen Gammastrahlen-Blazaren gesetzt.
Ground-based gamma-ray astronomy, which provides access to photons in the TeV energy range, has been a rapidly developing discipline over the past decades. In this thesis, the performance of the current- and next-generation imaging atmospheric Cherenkov telescopes VERITAS and CTA is evaluated using Monte Carlo simulations. Special emphasis is given to the possible extension of the duty cycle of CTA. It is shown that an increase of about 30% in observation time can be achieved through operation under partial moonlight without significant losses in performance. The increased observation time is especially important when studying astronomical objects which are variable at very high energies (VHE; E>50 GeV), such as active galactic nuclei (AGN), as this allows the extension of monitoring or multi-wavelength campaigns on these occasionally flaring sources. AGN represent to date about one third of the population of known VHE gamma-ray sources. Most of them are blazars, whose emission is dominated by non-thermal radiation of relativistic jets closely aligned to the line of sight of the observer. The blazar B2 1215+30 has been observed by VERITAS for nearly 100 hours between 2008 and 2012. The data analysis presented in this thesis yields a detection significance of 9.0 sigma and shows long-term variability with a relatively bright flux state in 2011. Multi-wavelength data are used to construct the spectral energy distribution of B2 1215+30 which is well described by a one-zone leptonic model. The model is presented in detail and possible constraints are investigated. The results of the modeling are discussed and put in context with other VHE-detected blazars.

Notre travail de recherche porte sur l’analyse de l’action du professeur et ses interactions avec les élèves dans le domaine spécifique de l’étude du numérique en Cours Préparatoires. L’objectif de notre thèse est d’analyser l’action du professeur et ses pratiques didactiques en classes, et formatives dans une Cellule d’Animation Pédagogique. La première partie comporte une présentation du contexte socio économique et éducatif du Niger. Nous nous interrogeons ensuite sur les pratiques professorales permettant ou non aux élèves de prendre de réelles responsabilités par rapport aux savoirs, et sur la pertinence du travail de conception collective de séances. Dans la deuxième partie, nous exposons nos outils théoriques, les travaux antérieurs en lien avec nos objets de recherche, et la problématique générale de notre travail. La troisième partie est consacrée à la démarche méthodologique qui fonde notre étude sur l’analyse des manuels, des vidéos de classe et les observations in situ. La quatrième partie examine les ressources mathématiques utilisées à l’écoleprimaire au Niger, en interrogeant l’influence de ces ressources sur les pratiques habituelles des professeurs enquêtés. Les cinquième et sixième parties analysent les séances empiriques en termes de topogénèse, et de recours aux systèmes sémiotiques pour étudier le savoir en jeu dans les situations didactiques. Dans la septième partie, nous proposons un dispositif innovant de formation continue sur la conception collective de leçons dans une CAPED. En conclusion, dans une huitième partie nous présentons d’abord une synthèse de nos résultats, et nous exposons ensuite les perspectives que ce travail de recherche offre en termes de propositions en vue de l'élaboration d'ingénieries didactiques qui pourraient permettre la mise en place d’un travail coopératif entre professeurs et chercheurs
Our research focuses on the teacher's action and his interactions with students in the specific field of the study of digital in grade 2. The objective of this PhD dissertation is to analyze the teacher's action and his didactic practices in classes, and training practices in a CAPED in the Niger context. The first part of this PhD dissertation includes a presentation of the socio-economic and educational contexts in Niger. Then we examine the teaching practices in order to see if they allow students to take or not real responsibilities in relation to knowledge, and the appropriateness of collective design work sessions.In the second part, we present our theoretical tools, previous work related to our research objects, and the general problem tackled by our work. The third part is devoted to our methodological approach based on the study of textbook analyze, videos of classes and field observations. The fourth section discusses the mathematic resources used in the primary education in Niger and question the impact of these resources on the observed teachers' usual practices. The fifth and sixth sessions analyze empirical lessons in terms of topogenesis, and semiotic systems to study the knowledge involved in the didactic situations. In the seventh part, we propose an innovative in-service training based on the design of lessons in a collective CAPED. In conclusion, in an eighth part we first present a summary of our results, and then we present the perspectives that this research offers in terms of further developments of didactic engineering that could allow the implementation of a collaborative work between teachers and researchers

Today, the main research field for the automotive industry is to find solutions for active safety. In order to perceive the surrounding environment, tracking nearby traffic objects plays an important role. Validation of the tracking performance is often done in staged traffic scenarios, where additional sensors, mounted on the vehicles, are used to obtain their true positions and velocities. The difficulty of evaluating the tracking performance complicates its development. An alternative approach studied in this thesis, is to record sequences and use non-causal algorithms, such as smoothing, instead of filtering to estimate the true target states. With this method, validation data for online, causal, target tracking algorithms can be obtained for all traffic scenarios without the need of extra sensors. We investigate how non-causal algorithms affects the target tracking performance using multiple sensors and dynamic models of different complexity. This is done to evaluate real-time methods against estimates obtained from non-causal filtering. Two different measurement units, a monocular camera and a LIDAR sensor, and two dynamic models are evaluated and compared using both causal and non-causal methods. The system is tested in two single object scenarios where ground truth is available and in three multi object scenarios without ground truth. Results from the two single object scenarios shows that tracking using only a monocular camera performs poorly since it is unable to measure the distance to objects. Here, a complementary LIDAR sensor improves the tracking performance significantly. The dynamic models are shown to have a small impact on the tracking performance, while the non-causal application gives a distinct improvement when tracking objects at large distances. Since the sequence can be reversed, the non-causal estimates are propagated from more certain states when the target is closer to the ego vehicle. For multiple object tracking, we find that correct associations between measurements and tracks are crucial for improving the tracking performance with non-causal algorithms.

This thesis focuses on the development of a robotic device to be used in parallel with observational learning techniques for facilitating the recovery of the upper limb in post-stroke patients. It has been shown in the existing observational learning literature that observational practice for the execution of goal-directed single arm movements can engage the mirror neuron system and motor areas involved in learning motor actions. On the other hand, robotic-based therapy protocols have proven successful in which participants are able to learn the required perception-action skill. However, robotics have not been overly successful in the generalization of learning to other tasks and this is an essential aspect on improving performance on Activities of Daily Life (ADL). Observational learning of motor skills has been shown to produce transfer across limbs and generalization across muscle groups in the same limb, as well as transfer to perceptual tasks. Therefore, our long-term hypothesis is that a combination of interactive robotics and action observation techniques might offer a greater benefit regarding transfer to ADLs in comparison to pure robotic training. The results from this research broaden the theoretical understanding of observational learning and drive the future development of rehabilitation protocols using the combination of robotic and observational learning techniques. We hypothesize that if the application of these techniques, for non-stroke individuals, yield benefits for the learning of motor/skill actions, then such paradigm will serve as a foundation in the future development of methods for facilitating the recovery of upper limb function after stroke.

Of all motor skills, manual reaching might be the one ability that matters most for infants’ perceptual, cognitive and social development. Reaching allows infants to learn about object properties, but also gives opportunities for socializing with others. The general aim of the present thesis was to study the importance of manual motor development in infancy from different perspectives; first, through examining stereopsis as a prerequisite for efficient reaching development, second, with regard to understanding others goal-directed reach actions by means of the mirror neuron system (MNS), and third, in relation to possible atypical development, with a specific focus on autism spectrum disorder (ASD). Study I shows that under monocular viewing conditions, infants at six, eight and 10 months of age perform slower and less accurate reaches. Longer times to object contact during monocular trials specifically imply that motor prediction is less effective when depth and distance information is compromised. Study II demonstrates that, by eight months of age, infants seem to have a MNS that functions in a similar manner to the adult MNS, thus activity can be registered over the motor cortex when infants simply observe an action they can master themselves. This activation is predictive, indicating anticipation of the goal of the observed reach. Study III indicates that infants at elevated familial risk for ASD present with reduced prospective motor control at 10 months of age. Compared to a low-risk control sample, high-risk infants perform reactive rather than predictive reach actions. Follow-up assessment at 36 months will show whether this measure can be used as a predictive diagnostic marker for ASD. The main contribution given by this work is the insight that it is important to take manual motor aspects into account when considering typical as well as atypical cognitive and social development, and in addition, that motor prediction is a key factor behind being able to timely execute and understand reaching actions.

The present International Celestial Reference Frame (ICRF), the ICRF-3 is based on a catalogue of 4536 quasar positions obtained from Very Long Baseline Interferometry (VLBI) radio measurements. This radio frame is crucial for many applications, from measurements of Earth’s orientation in space to spacecraft navigation and measurements of sea-level rise. However, the deficit in ICRF source density in the South and lack of dedicated imaging campaigns in the South, to monitor structural changes, remain a big concern. These ICRF sources can exhibit spatially extended emission structures that can have a significant effect on astrometric VLBI measurements. The Celestial Reference Frame Deep South (CRDS) is a dedicated astrometric VLBI programme to observe Southern ICRF sources on a regular basis. In an effort to improve the situation in the South, these CRDS sessions have recently been optimized for VLBI imaging. In this thesis, I present VLBI images and source structure analysis results for southern ICRF sources observed in four of these CRDS sessions. For some of these sources, I present the very first high-resolution radio images. I also present results from source structure analysis and a corresponding assessment of astrometric quality, and I also present results from efforts to increase the ICRF source density in the South.
Mathematical Sciences
Ph. D. (Astronomy)

Tesis (Doctor en Astronomía)--Universidad Nacional de Córdoba, Facultad de Matemática, Astronomía, Física y Computación, 2018.
Los núcleos activos de galaxias (AGN) se diferencian de las galaxias "normales" por el hecho de emitir una fracción significativa de energía que no puede ser explicada como resultado de procesos estelares. Esta fracción, proveniente de una región central muy compacta de la galaxia, es muy difícil de cuantificar. Los AGN del tipo "Narrow Line Seyfert 1" (NLS1) son una subclase de AGN con características de Seyfert 1 pero sin líneas anchas evidentes, lo cual implica grandes interrogantes sobre su estructura, dinámica y fuente central de excitación. A este tipo de galaxias se las define con el criterio de que el ancho a mitad de altura (FWHM) de la componente ancha de Hβ sea menor que 2000 km s-1 y que el cociente [OIII]λ5007/Hβ sea menor que 3. El estudio de los NLS1 puede brindarnos importante información sobre la evolución de los AGN y los mecanismos de ionización dominantes en las regiones más internas de estos objetos. Para estudiar estos objetos, seleccionamos una muestra de espectros a z < 0,1 obtenidos a partir del Sloan Digital Sky Survey. Utilizando la técnica de la síntesis espectral, separamos las diferentes componentes que contribuyen al espectro observado, a saber la componente estelar y no-estelar, y también la emisión del gas ionizado. En este trabajo se pretende cuantificar la contribución del núcleo activo al total del flujo observado y determinar el índice espectral más representativo en la región óptica del espectro en las galaxias NLS1. A partir de la técnica de síntesis espectral, también obtuvimos información sobre las diferentes poblaciones estelares presentes en estas galaxias. Por medio del espectro de emisión del gas, se determinó la dinámica y luminosidad de diferentes líneas de emisión, con las cuales estimamos masas de agujeros negros y tasas de acreción. Por último, se presenta un estudio detallado de la dinámica del gas y en particular de los vientos en la región central de la galaxia SDSS J093643.13+505249.6. Para ello se realizaron observaciones utilizando el Gemini Multi-Object Spectrographs con el Integral Field Unit (GMOS – IFU) en la región de Hβ + [OIII]λ5007 del espectro. De esta manera, obtuvimos mapas de flujo y de velocidades de estas líneas de emisión, con los cuales estimamos la extensión de los vientos en la región central de esta galaxia.
Active galactic nuclei (AGN) differ from "normal" galaxies in that they emit a significant fraction of energy that cannot be explained as the result of stellar processes. This fraction, coming from a very compact central region of the galaxy, is very difficult to quantify. Narrow Line Seyfert 1 (NLS1) AGNs are a subclass of AGNs with Seyfert 1 characteristics but without obvious broad lines, which implies big questions about their structure, dynamics and central source of excitation. These types of galaxies are defined by the criterion that the width at half maximum (FWHM) of the broad Hβ component is less than 2000 km s-1 and that the [OIII]λ5007/Hβ ratio is less than 3. The study of NLS1s can provide us with important information about the evolution of AGNs and the dominant ionization mechanisms in the innermost regions of these objects. To study these objects, we selected a sample of spectra at z < 0.1 obtained from the Sloan Digital Sky Survey. Using the spectral synthesis technique, we separate the different components contributing to the observed spectrum, namely the stellar and non-stellar component, and also the emission from ionized gas. In this work we aim to quantify the contribution of the active nucleus to the total observed flux and to determine the most representative spectral index in the optical region of the spectrum in NLS1 galaxies. From the spectral synthesis technique, we also obtained information about the different stellar populations present in these galaxies. By means of the gas emission spectra, we determined the dynamics and luminosity of different emission lines, with which we estimate black hole masses and accretion rates. Finally, a detailed study of the gas dynamics and in particular of the winds in the central region of the galaxy SDSS J093643.13+505249.6 is presented. For this purpose, observations were made using the Gemini Multi-Object Spectrographs with the Integral Field Unit (GMOS - IFU) in the Hβ + [OIII]λ5007 region of the spectrum. In this way, we obtained flux and velocity maps of these emission lines, with which we estimated the extent of the winds in the central region of this galaxy.
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Fil: Oio, Gabriel Andrés. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía, Física y Computación; Argentina.

Community development and in particular participatory development is about people. This means that the person who studies or practices participatory development or any other of the participatory pratices should have a particular way of thinking about people. The main aim motivating this study was to investigate the paradigm/s about people on which participatory practices are based. This included a literature research on five participatory practices namely participatory development; participatory communication; participatory learning; participatory research; and participatory management. A guideline for paradigm analysis was developed by using Schriver's (1995) and Capra's (1996) descriptions of a paradigm as well as ideas of hermeneutics. From the paradigm analysis on the participatory practices two themes emerged: A shift from modernism to post modernism in the thinking processes and participatory practices. From the participatory practices the same concepts repeatedly emerged indicating a similar paradigm for all the participatory practices. Three post modern theories were therefore applied to enhance the description of the different concepts. The end result of this study is the development of an evolving paradigm for participatory practices in order to give enhanced meaning to concepts in the participatory vocabulary. Finally a critical reflection was done on the post modern research process.
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Social Work
D.Phil. (Social Work)