The purpose of this study was to explore differences in movement initiation and execution, and their associations with amount of physical activity (PA) and cognitive abilities, in 6 to 8 year old children born PT compared to peers born at term. The sample consisted of in total 78 children divided in subgroups, 16 born very preterm (VPT), 24 born moderate preterm (MPT) and 38 age matched controls born at term (FT) with no diagnosed cognitive or motor impairments. Three-dimensional (3D) kinematic recordings of wrist movements during two bimanual tapping tasks (horizontal and vertical) were finalized and kinematic outcome measures were investigated in relation to PA and performance on WISC-IV. Children born VPT showed significantly longer Latency times and longer Duration of movement execution compared to children born MPT and FT. No significant within group correlations between PA and movement performance were found. Duration of movement execution and Total duration of movement execution were negatively associated with Full-scale intelligence quotient (FSIQ) and processing speed index (SI) in the PT group. Early school aged children born VPT need longer planning time to initiate and execute goal directed bimanual movements, compared to peers born MPT and FT. Kinematic performance did not evidently associate with amount of PA, although kinematics, by means of longer Latency time and Duration of movement execution, negatively associated with SI. / Syftet med denna studie var att undersöka skillnader i initiering och utförande av en rörelse samt deras associationer med fysisk aktivitet och kognitiv förmåga hos förtidigt födda barn i åldrarna 6 till 8 år samt åldersmatchade fullgångna jämnåriga barn. Urvalet bestod av total 78 barn uppdelade i subgrupper, 16 väldigt förtidigt födda, 24 moderat förtidigt födda och 38 åldersmatchade fullgångna kontroller utan några kända kognitiva eller motoriska nedsättningar. Tredimensionella (3D) kinematiska registreringar av handledsrörelser under två bimanuella knapptrycksuppgifter (horisontell och vertikal) genomfördes. Utfallet av rörelsemätningarna studerades i association till fysisk aktivitet och resultat på WISC-IV. Väldigt förtidigt födda barn visade längre latenstid och längre duration av rörelse jämfört med moderat förtidigt födda och fullgångna barn. Inga signifikanta inom grupps korrelationer mellan fysisk aktivitet och rörelseutförande hittades. Utförandets duration samt hela utförandets duration associerade negativt med IQ kvot och processhastighet (SI) hos för tidigt födda barn. Väldigt förtidigt födda barn i tidig skolålder behöver mer tid till rörelseplanering, initiering och utförande av viljestyrda målinriktade rörelser jämfört med jämnåriga barn födda senare i graviditeten. Kinematiskt utfall associerade inte signifikant med fysisk aktivitet, däremot associerade kinematiskt utfall, i form av längre latenstid och duration av utförande, negativt med kognitiv processhastighet.

La spectroscopie sans fente a longtemps été considérée comme une technique compliquée de part ses effets d’auto- et d’inter-contamination. Toutefois, depuis l’ère des instruments du Télescope Spatial Hubble qui offrent un bruit de fond faible et une bonne résolution spatiale, la spectroscopie sans fente est devenue un outil largement utilisé pour les sondages spatiaux astrophysiques et cosmologiques. Dans ce contexte, nous nous sommes intéresser à l’application de cette technique pour l’étude individuelle d’objets. Dans les sondages actuels, l’analyse de ces spectres s’effectue généralement à partir de méthodes inverses qui ne tiennent pas compte de l’effet d’auto-contamination et mé- langent donc les propriétés morphologiques et spectrales de la galaxie. Les objectifs de cette thèse sont tout d’abord de prendre en compte cet effet de contamination qui dégrade la résolution spec- trale effective en fonction de l’extension spatiale de la source, afin de mesurer plus précisément le redshift et autres propriétés spectrales intégrées. Nous explorons aussi la faisabilité de la mesure de quantitées spatialement résolues telle que la cinématique interne des galaxies. Nous construisons alors un modèle complet qui peut être quantitativement comparé aux observations actuelles dans une approche forward. Ce modèle est par la suite testé sur des données sélectionnées des relevés GLASS et 3D-HST, afin de contraindre en particulier le redshift et les paramètres cinématiques modélisant la courbe de rotation de la galaxie. Notre approche forward permet d’atténuer l’effet d’auto-contamination et donc d’améliorer la précision sur la mesure du redshift. Dans un sous-échantillon de galaxies spirales isolées et résolues, il est alors possible de contrainte assez significativement les paramètres cinématiques. Nous étudions également les systématiques liées aux hypothèses de notre modèle grâce à des simulations avec les données du relevé de spectroscopie à champ intégral MaNGA, qui tendent à montrer que la mesure de ces paramètres reste assez difficile pour la plupart des données récentes de spectroscopie sans fente. Néanmoins, ces simulations indiquent que le modèle forward contraint relativement bien le redshift. Enfin, ces travaux montrent des applications prometteuses pour les futures grands relevés spectroscopiques tel que Euclid / Slitless spectroscopy has long been considered as a complicated and confused technique because of its self- and cross-confusion effets. However, since the era of the Hubble Space Telescope (HST) instruments which offer a low background and fine spatial resolution, slitless spectroscopy has become an adopted cosmological survey tool to study galaxy evolution from space. Within this context, we investigate its application to single object studies. In recent surveys, the spectra analysis is usually done using backward extraction which mixes spatial and spectral properties and therefore does not take into account self-confusion effect. The goals of this PhD is firstly to include this effect which degrades the effective spectral resolution (which depends on the extent of the source), in order to make the redshift and other integrated spectral features measure- ments more accurate. We also explore the feasibility to measure spatially resolved quantities such as galaxy kinematics. We build a complete forward model to be quantitatively compared to actual slitless observations. The model is tested on selected observations from 3D-HST and GLASS surveys, to estimate redshift and kinematic parameters (modeling the galaxy rotation curve) on several galaxies mea- sured with one or more roll angles. Our forward approach allows to mitigate self-confusion effect, and therefore to increase the precision of redshift measurements. In a sub-sample of well-resolved spiral galaxies from HST surveys, it is possible to significantly constrain galaxy rotation curve pa- rameters. We also study the systematics effects induced by the hypothesis of our model by building slitless simulations with the data of the integral field spectrograph survey MaNGA. These simu- lations suggest that the precise measurement of the kinematics parameters is difficult for most of the current slitless observations. Nethertheless, they point out that this forward model contrains significantly well the redshift. Finally, this work is promising for future large slitless spectroscopic surveys such as Euclid

In this work we study the processes near the Galactic centre, which serves as a paradigm for low- luminosity galactic nuclei. The introductory part of the thesis is a brief review on the radio source Sagittarius A* in the Galactic centre and on its immediate surroundings. The main part of the thesis focuses on the hypothetical population of neutron stars that should be present in large numbers in this region. We analyse the predictions concerning the encounters of this observationally unexplored population with the ambient interstellar medium and we discuss the distribution of their interaction modes with respect to the parameters of the system. We find out that this distribution is strongly dependent on the density of the ambient medium, whereas only weakly dependent on its temperature. The effect of the prolongation of rotational period is negligible on the time-scale of about ten thousand years. In the second part, we predict the evolution of the high-eccentricity passages of clouds and dust- enshrouded stars (with pericentre distances at about 1000 Schwarzschild radii from the black hole). In all studied cases a major part of the matter is diverted from the original path. Powered by TCPDF (www.tcpdf.org)

The observed properties of galaxies are intricately connected to their respective evolutionary histories. Establishing these connections – tying the morphologies, dynamics, and other properties of galaxies to the dominant events and processes from which they originate – is the central challenge in creating a self-consistent framework for how galaxies form and evolve. Overcoming this challenge requires that two criteria be satisfied: (1) accurate characterization of the physical states of galaxies; and (2) creation of models that connect the observed features of galaxies to their evolutionary histories. This thesis chiefly concerns the identification and characterization of morphological and kinematic indicators for structural transformation in galaxies and their connections to galaxy mergers – including merger status (merger or non-merger) and merger stage. Accurate measurement of the morphological structures of galaxies is a cornerstone for making connections to their evolutionary pathways. However, without significant overlap between the observational footprints of deep and shallow galaxy imaging surveys, the extent to which structural measurements for large galaxy samples are robust to image quality (e.g. depth, spatial resolution) cannot be established. Deep images from the Sloan Digital Sky Survey (SDSS) Stripe 82 co-adds provide a unique solution to this problem – offering 1.6 − 1.8 magnitudes improvement in depth with respect to SDSS Legacy images. Having similar spatial resolution to Legacy, the co-adds make it possible to examine the sensitivity of parametric morphologies to depth alone. Using the GIM2D surface-brightness decomposition software, I provide public morphology catalogs for 16,908 galaxies in the Stripe 82 ugriz co-adds. The methods and selection are completely consistent with those of previous analyses in the shallow images. Measurements in the deep and shallow images are rigorously compared. No systematics in total magnitudes and sizes are found except for faint galaxies in the u-band and the brightest galaxies in each band. However, characterization of bulge-to-total fractions is significantly improved in the deep images. Furthermore, statistics used to determine whether single-Sérsic or two-component (e.g. bulge+disc) models are required become more bimodal in the deep images. Lastly, I show that morphological asymmetries (commonly linked to mergers) are enhanced in the deep images and that the enhancement is positively correlated with the asymmetries measured in Legacy images. Recently, machine learning has become a popular tool to quantify galaxy morphologies and identify mergers – exploiting the often disturbed and asymmetric morphological features present in merging galaxies. However, this technique relies on using an appropriate set of training data to be successful. By combining hydrodynamical simulations, synthetic observations and convolutional neural networks (CNNs), I quantitatively assess how realistic simulated galaxy images must be in order to reliably classify real mergers. Specifically, I compare the performance of CNNs trained with two types of galaxy images, stellar maps and images with full radiative transfer through internal dust, each with three levels of observational realism: (1) no observational effects (idealized images), (2) realistic sky and point spread function (semi-realistic images), (3) insertion into a real sky image (fully realistic images). I show that networks trained on either idealized or semi-real images have poor performance when applied to survey-realistic images. In contrast, networks trained on fully realistic images achieve 87.1% classification performance. Importantly, the level of realism in the training images is much more important than whether the images included radiative transfer, or simply used the stellar maps (87.1% compared to 79.6% accuracy, respectively). Therefore, one can avoid the large computational and storage cost of running radiative transfer with a relatively modest compromise in classification performance. Making photometry-based networks insensitive to colour incurs a very mild penalty to performance with survey-realistic data (86.0% with r-only compared to 87.1% with gri). This result demonstrates that while colour can be exploited by colour-sensitive networks, it is not necessary to achieve high accuracy and so can be avoided if desired. I provide the public release of the statistical observational realism suite, RealSim, as a companion to this work. Galaxy kinematics derived from observational integral field spectroscopy (IFS) may offer an orthogonal and highly-complimentary basis to photometry for accurately identifying and characterizing observed galaxy mergers. As with morphology, mergers can trigger kinematic disturbances in galaxies resulting in irregular and asymmetric kinematic structure. However, these kinematic disturbances are not always reflected in the morphologies. The current and future state-of-the-art IFS instruments which provide spatially-resolved kinematics for many thousands of galaxies make kinematic merger studies statistically viable. Anticipating the demand for realistic synthetic IFS and kinematic data for calibrating merger classification models with simulations, I present RealSim-IFS: a novel tool that emulates the instrumental response of current and future fibre-based IFS instruments. Components of RealSim-IFS are tested on real IFS data from the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey to demonstrate the high precision that is achieved by RealSim-IFS. In a further demonstration with RealSim-IFS, I generate realistic synthetic MaNGA kinematic observations for a sample of galaxies from the IllustrisTNG cosmological hydrodynamical simulations. The survey-realistic kinematic maps for post-merger galaxies are compared with non-merging galaxies to illustrate the potential role of kinematics in enabling more accurate identification and characterization of galaxy mergers – either independently or in tandem with photometry. / Graduate

Aging in humans is often associated with reduced muscle strength and difficulty in elevating the arm and sustaining it at a certain position. The aim of this master thesis is to propose a number of technical solutions integrated into a complete electronic system which can be used to support the user's muscle capacity and partially resist gravitational load. An electronic system consisting of sensors, a control unit and an actuator has been developed. The system is able to detect the user's motion intention based on an angle detection algorithm and perform kinematic control over the user's arm by adjusting the level of support at different degrees of elevation. A force control algorithm has been developed for controlling the actuating mechanism, providing the user with a natural and intuitive support during arm elevation. The implemented system is a first step towards the development of a medical assistive device for the elderly or patients with reduced muscle strength allowing them to independently perform a number of personal activities of daily life where active participation of the upper limb is required.

Ankle sprains are among the most common injuries for participants in running and jumping sports. Following an initial sprain injury, many (30-40%) will develop chronic ankle instability (CAI), characterized by a perception of instability and repeated sprain injuries. Quasi-static test methods indicate poor postural stability and joint position sense (JPS) as associated motor control deficits. Little research, though, has investigated ankle motor control under dynamic (simulated sport) or fatigue conditions. To better understand factors contributing to the increased sprain rate in adults with CAI, three studies were completed investigating the roles of running speed, fatigue, and ankle bracing on motor control in adults with CAI. First, two groups with and without ankle instability performed dynamic athletic maneuvers at each of two running speeds. Joint kinematics and kinetics were measured to identify differences in motor control strategies. Participants also completed two quasi-static tests (JPS and single leg drop landings). The level of correspondence between quasi-static and dynamic test methods was of particular interest. A second study compared fatigue development and fatigue adaptations when executing single leg drop landings. Strength loss and ratings of perceived exertion measured fatigue development, and joint kinematics, kinetics, and muscle activation quantified drop landing performance. A final study examined whether ankle braces, a common treatment for ankle sprains, retained their effectiveness when an athlete was fatigued. JPS and ankle stiffness were measured before and after a fatigue protocol while using each of three brace conditions. Overall, results indicated that adults with CAI exhibit distinct adaptations to changes in speed and to fatigue that may increase their risk for ankle reinjury. Specific changes, however, depended on the particular activity being performed. Single leg drop landing kinematics may be a good representation of kinematics during dynamic athletic performance. Neither test brace improved JPS following fatigue, but each may be effective in providing mechanical stiffness compared to an unbraced condition. The effectiveness of a particular test brace, however, may be gender-specific. Future work should focus on identifying the benefits of different braces under broader conditions to help inform brace selection. / Ph. D.

In this work, we study two problems in quantum field theory from a boundary point of view. Our perspective is motivated by the bootstrap philosophy, which aims to understand how principles such as kinematics, unitarity, and symmetry constrain physical observables. Regarding kinematics, we actually first relax the unitarity constraint and investigate thenon-unitary representations of the boundary superconformal algebra for AdS4 with N = 2 supercharges. In particular, we identify multiplets containing partially massless (PM) fields, as well as other exotic shortening conditions and structures exclusive to the nonunitary regime. Then, turning on interactions, we study a problem centered in dynamics: we investigate the structure of the flat space wavefunctional in scalar field theories with nonlinearly realized symmetries. In particular, we highlight the so-called exceptional scalar field theories, which are the nonlinear sigma model, Dirac-Born-Infeld, and (special) galileon theories. We find that nonlinearly realized symmetries imply soft theorems which must be obeyed by the wavefunction. Moreover, we develop bootstrap techniques utilizing this information along with the singularity structure of the wavefunction to fix its form. In addition, we systematize this construction into a novel set of recursion relations.

This study examined kinematic and acoustic adaptation following the placement of electromagnetic articulography (EMA) sensors, which measure speech articulator movements. Sixteen typical native English speakers had eight EMA sensors attached to obtain kinematic data: three to the tongue (front, mid, and back at midline), one on the lower incisors (jaw), two on the lips (one on each lip at midline), and two reference sensors on the eyeglass frames worn by the participants. They repeated the same sentence stimuli 5 times every two minutes (0, 2, 4, 6 minutes post-attachment) while both acoustic and kinematic data were recorded. Global kinematic measures of tongue activity were computed using articulatory stroke metrics, while point measures were gathered from one syllable in the target sentence. The first two formant frequencies of that syllable were measured. Statistical analysis revealed several significant changes over time and differences between genders. There was a significant increase in the syllable speed and decrease in sentence duration over time. The first formant was significantly lower over time correlating with decreased hull area, representing higher tongue position and smaller movements as speakers adapted to the sensors. Tongue displacement during the syllable production decreased over time; there was not a significant gender difference for displacement measures. The number of articulatory strokes decreased over time, suggesting improved articulatory steadiness. It can be concluded that participants demonstrated faster, smaller movements over time, but it is not clear how much of the change was a result of kinematic adaptation or task familiarity. Future research is needed to compare the direct relationship between kinematic, acoustic, and perceptual measures in response to the attachment of these EMA sensors.

This paper compares the two heuristic inverse kinematics methods: Forward And Backward Reaching Inverse Kinematics (FABRIK) and Cyclic Coordinate Descent (CCD) in the use cases concerning quadruped models. Unoptimised versions of the two algorithms were implemented into a game engine and evaluated on a quadruped model. The two algorithms were evaluated by computational time, iterations and average error. The results show that FABRIK outperformed CCD in all of our test scenarios, in number of iterations required, average error as well as function execution time. However, results also showed that FABRIK was less superior when targets were barely within reach, since one leg might be able to reach a target, but two connected legs might not be able to reach two targets because of their interference with each other. This suggests that to improve on FABRIK it should be optimised when considering a bipedal or quadruped model. / Den här artikeln jämför de två heuristiska Inverse Kinematics-metoderna: Forward And Backward Reaching Inverse Kinematics (FABRIK) och Cyclic Coordinate Descent (CCD) i användningsfallet fyrbenta modeller. Ooptimerade versioner av de två algoritmerna implementerades i en spelmotor och utvärderades på en fyrbent modell. De två algoritmerna utvärderades därefter baserat på beräkningstid, antal iterationer och avstånd till målet. Resultaten visar att FABRIK överträffade CCD i alla testscenarium, i antal iterationer, avstånd till mål samt funktionskörningstid. Resultaten visade dock även att FABRIK var mindre överlägsen när målen var precis utom räckhåll; detta då ett ben kunde nå ett mål om det utvärderades ensamt, men när benet kopplades samman med motstående ben via en höftled kunde inget av benen nå sina mål på grund av att de påverkade varandra. Detta tyder på att för att förbättra FABRIK bör den optimeras till att ta hänsyn till huruvida modellen har två eller fyra ben.

In gymnastics, the performance is evaluated by a subjective rating, whereby one of the biggest problems is the validity and reliability of judgment. The process of observing and evaluating complex motor skills such as those found in gymnastics is located in the cyclical interaction between perception and action, raising the key question, how the quantifiable movement execution is related to the perceived movement quality. Therefore, the thesis aimed at a first step to kinematically analyze selected prototypical gymnastics skills to investigate at a second step the underlying perceptual-cognitive mechanism when observing and evaluating those skills. In the analysis of kinematics, it was focused on the classification and structuring of temporal-spatial continuous kinematic movement patterns and their relationship to the perceived movement quality. In the investigation of the perceptual-cognitive mechanism, it was focused on how skill kinematics are related to the perceived movement quality. Furthermore, the gaze pattern was evaluated and examined during the observation. Five consecutive studies were conducted to achieve those objectives. It was shown that complex gymnastics skills can be kinematically structured into prototypical movement patterns, which differ concerning certain variant and invariant kinematic characteristics. The results of a model-based approach to predict perceived movement quality out of the kinematics of gymnastics skills showed a significant relationship between the predicted score and the true score. Overall, the models worked best for the vault skill, which was the shortest skill with the least spatial variability. Out of all models, the neural network approach showed the best results. Furthermore, it was found, that the similarity of the kinematics of gymnastics skills did not correlate with the similarity of the perceived movement quality. During the evaluation, the gaze pattern was influenced by the manipulation of the amount of non-kinematic information. This was especially the case for the last skill. Expertise seemingly influenced the perceptual-cognitive mechanism partially, but no clear pattern was visible. The results provided first insights on how gymnastics performances and the resulting judgment scores are related. The complexity of gymnastics skills and additionally, the similarity of the performance level in high elite sport is increasing. This challenge as well as the fast development of technologies leads to the occurrence of computer-based judging systems. Their reliability and validity, but also their challenges and opportunities in artistic gymnastics should be further investigated.