• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 199
  • 65
  • 49
  • 48
  • 18
  • 14
  • 13
  • 9
  • 6
  • 4
  • 4
  • 4
  • 4
  • 4
  • 4
  • Tagged with
  • 521
  • 66
  • 56
  • 42
  • 33
  • 31
  • 31
  • 28
  • 28
  • 28
  • 27
  • 27
  • 27
  • 27
  • 23
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
361

Excitabilité du système miroir : une étude de stimulation magnétique transcrânienne sur le chant et le langage

Royal, Isabelle 09 1900 (has links)
La perception de mouvements est associée à une augmentation de l’excitabilité du cortex moteur humain. Ce système appelé « miroir » sous-tendrait notre habileté à comprendre les gestes posés par une tierce personne puisqu’il est impliqué dans la reconnaissance, la compréhension et l’imitation de ces gestes. Dans cette étude, nous examinons de quelle façon ce système miroir s’implique et se latéralise dans la perception du chant et de la parole. Une stimulation magnétique transcrânienne (TMS) à impulsion unique a été appliquée sur la représentation de la bouche du cortex moteur de 11 participants. La réponse motrice engendrée a été mesurée sous la forme de potentiels évoqués moteurs (PÉMs), enregistrés à partir du muscle de la bouche. Ceux-ci ont été comparés lors de la perception de chant et de parole, dans chaque hémisphère cérébral. Afin d’examiner l’activation de ce système moteur dans le temps, les impulsions de la TMS ont été envoyées aléatoirement à l’intérieur de 7 fenêtres temporelles (500-3500 ms). Les stimuli pour la tâche de perception du chant correspondaient à des vidéos de 4 secondes dans lesquelles une chanteuse produisait un intervalle ascendant de deux notes que les participants devaient juger comme correspondant ou non à un intervalle écrit. Pour la tâche de perception de la parole, les participants regardaient des vidéos de 4 secondes montrant une personne expliquant un proverbe et devaient juger si cette explication correspondait bien à un proverbe écrit. Les résultats de cette étude montrent que les amplitudes des PÉMs recueillis dans la tâche de perception de chant étaient plus grandes après stimulation de l’hémisphère droit que de l’hémisphère gauche, surtout lorsque l’impulsion était envoyée entre 1000 et 1500 ms. Aucun effet significatif n’est ressorti de la condition de perception de la parole. Ces résultats suggèrent que le système miroir de l’hémisphère droit s’active davantage après une présentation motrice audio-visuelle, en comparaison de l’hémisphère gauche. / The perception of movements is associated with increased activity in the human motor cortex. This system underlies our ability to understand one’s actions, as it is implicated in the recognition, understanding and imitation of actions. In this study, we investigated the involvement and lateralization of this “mirror neuron” system (MNS) in the perception of singing and speech. Transcranial magnetic stimulation (TMS) was applied over the mouth representation of the motor cortex in 11 participants. The generated motor response was measured in the form of motor evoked potentials (MEPs), recorded from the mouth muscle. The MEPs were compared for the singing and speech conditions in each cerebral hemisphere. Furthermore, to investigate the time course of the MNS activation, TMS pulses were randomly emitted in 7 time windows (ranging from 500 to 3500 milliseconds after stimulus onset). The stimuli for the singing condition consisted in 4-second videos of singers producing a 2-note ascending interval. Participants had to judge whether the sung interval matched a written interval, previously presented on the screen. For the speech condition, 4-second videos of a person explaining a proverb were shown. Participants had to decide whether this explanation matched a written proverb previously displayed on the screen. Results show that the MEP amplitudes were higher after stimulation of the right hemisphere in the singing condition. More specifically, sending TMS pulses between 1000 and 1500 milliseconds over the right hemisphere yielded higher MEPs as compared to the left hemisphere. No effect was found in the speech condition. These results suggest that the right MNS is more activated after an audiovisual motor presentation compared to the left hemisphere.
362

A contribution to photonic MEMS : study of optical resonators and interferometers based on all-silicon Bragg reflectors

Malak Karam, Maurine 17 November 2011 (has links) (PDF)
This research work has been conducted to introduce a novel class of Fabry-Perot (FP) resonators : curved FP cavity based on coating-free Bragg mirrors of cylindrical shape, obtained by silicon micromachining. Another specificity is the rather large cavity lengths (L>200 µm) combined with high quality factor Q (up to 104), for the purpose of applications requiring cavity enhanced absorption spectroscopy, in which the product Q.L is a figure of merit. In this contest, the basic architecture has been modeled analytically to know the high order transverse modes supported by such cavities. Hence, the experimental conditions which lead to preferential excitation (or rejection) of these modes have been tested experimentally leading to the validation of our theoretical model and to a better understanding of the cavity behaviour. A second architecture, based on the curved FP together with a fiber rod lens has been developed for the purpose of providing stable designs. It was also modeled, fabricated and characterized leading to the expected performance improvements. On another side, a highlight on one of the potential applications that we identified for the curved cavities is presented by inserting the cavity into an electro-mechanical system. It consists of exciting and measuring tiny vibration through opto-mechanical coupling in a MEMS mechanical resonator embedding an FP cavity.Finally, as a complement to our study on resonators, we started exploring applications of optical interferometers based on similar micromachined silicon Bragg mirrors. For this purpose, an optical measurement microsystem was designed, fabricated and characterized ; it consists of an optical probe for surface profilometry in confined environments, based on an all-silicon Michelson interferometer
363

Effect of timing training in golf and soccer players : skill, movement organization, and brain activity

Sommer, Marius January 2014 (has links)
Background Although trainers and athletes consider ‘good timing skills’ to be critical for optimal sport performance, little is known in regard to how sport-specific skills may benefit from timing training. Thus, assuming that all motor performances are mediated by an internal timing mechanism, enhanced motor timing is expected to have positive effects on both planning and execution of movement performance, and consequently on complex sports actions as golf or soccer. Accordingly, in order to increase our knowledge of the importance of motor timing and possible effects of timing training, this thesis examines the effects of synchronized metronome training (SMT), thought to improve the execution of motor programs and to enhance motor skills in golf and soccer players. Methods Study I examined the effects of SMT on motor timing abilities and its potential effect on golf shot accuracy and consistency in 25 experienced male golfers. Additionally, Study II examined the effects of SMT on the spatiotemporal movement organisation and dynamics of the golf swing performance, as captured by kinematic measurements and analyses in thirteen male golfers. Study III examined the effect of SMT on accuracy and variability in a soccer specific, cross-pass task in elite and sub-elite female soccer players. Moreover, the underlying brain activity was assessed by means of functional magnetic resonance imaging (fMRI) to investigate the corresponding neural activity when passively observing the cross-pass task, and the possible pre- to post training effects. Results SMT was shown to improve motor timing ability, by means of less timing asynchrony and with associated changes in timing variability, in both golf- and soccer-players. Additionally, significant improvements in golf shot and soccer cross-pass performance, by means of significant increase in outcome accuracy combined with a decrease in outcome variability was found. From the kinematic investigation in Study II, results indicate that improved motor timing, as an effect of SMT, lead to a more coordinated and dynamic swing performance, and with decreased variability in the temporal structure of the swing motion. Finally, it was found that SMT induces changes in the activity of the action observation network (AON), underpinning action observation and action prediction, by means of decreased activation within bilateral cerebellum, fusiform gyrus and superior temporal gyrus. These findings hint at a more efficient pattern of neural recruitment during action observation, after SMT. Conclusion In summary, this thesis provides evidence that four weeks of SMT improved the participant’s motor timing and synchronization abilities, and showed influence on both behavioral and neurophysiological motor programs and skill performance in golf and soccer players. Thus, by improved outcome accuracy and decreased variability, affecting the coordinated movement pattern and organisation, as well as affecting the associated underlying brain activation.
364

An Embodied Account of Action Prediction

Elsner, Claudia January 2015 (has links)
Being able to generate predictions about what is going to happen next while observing other people’s actions plays a crucial role in our daily lives. Different theoretical explanations for the underlying processes of humans’ action prediction abilities have been suggested. Whereas an embodied account posits that predictive gaze relies on embodied simulations in the observer’s motor system, other accounts do not assume a causal role of the motor system for action prediction. The general aim of this thesis was to augment current knowledge about the functional mechanisms behind humans’ action prediction abilities. In particular, the present thesis outlines and tests an embodied account of action prediction. The second aim of this thesis was to extend prior action prediction studies by exploring infants’ online gaze during observation of social interactions. The thesis reports 3 eye-tracking studies that were designed to measure adults’ and infants’ predictive eye movements during observation of different manual and social actions. The first two studies used point-light displays of manual reaching actions as stimuli to isolate human motion information. Additionally, Study II used transcranial magnetic stimulation (TMS) to directly modify motor cortex activity. Study I showed that kinematic information from biological motion can be used to anticipate the goal of other people’s point-light actions and that the presence of biological motion is sufficient for anticipation to occur. Study II demonstrated that TMS-induced temporary lesions in the primary motor cortex selectively affected observers’ gaze latencies. Study III examined 12-month-olds’ online gaze during observation of a give-and-take interaction between two individuals. The third study showed that already at one year of age infants shift their gaze from a passing hand to a receiving hand faster when the receiving hand forms a give-me gesture compared to an inverted hand shape. The reported results from this thesis make two major contributions. First, Studies I and II provide evidence for an embodied account of action prediction by demonstrating a direct connection between anticipatory eye movements and motor cortex activity. These findings support the interpretation that predictive eye movements are driven by a recruitment of the observer’s own motor system. Second, Study III implicates that properties of social action goals influence infants’ online gaze during action observation. It further suggests that at one year of age infants begin to show sensitivity to social goals within the context of give-and-take interactions while observing from a third-party perspective.
365

Adult support for lesbian, gay, bisexual, transgender, queer and questioning (LGBTQQ) youth in high school : a project based upon an independent investigation /

Starfield, Amanda Louise. January 2008 (has links)
Thesis (M.S.W.)--Smith College School for Social Work, Northampton, Mass., 2008. / Typescript. Includes bibliographical references (leaves 65-69).
366

Manual Motor Development in Infancy : Execution and Observation of Actions

Ljunghammar Ekberg, Therese January 2015 (has links)
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.
367

Interaction entre le schéma corporel et les comportements moteurs dans l'anorexie mentale et chez le sujet sain / Interaction between body schema and motor behaviors in anorexia nervosa and healthy subjects

Metral, Morgane 06 April 2016 (has links)
Le schéma corporel est une représentation interne et dynamique du corps, de la morphologie, et des positions relatives des segments corporels. Celui-ci serait le support à partir duquel une motricité adaptée va pouvoir se mettre en place. L’objectif principal de ce travail doctoral était d’évaluer plus précisément cette intrication entre schéma corporel et comportements moteurs. Nous avons ainsi évalué à la fois l'effet de différentes distorsions du schéma corporel sur le comportement moteur, et inversement l'effet des comportements moteurs sur la modulation éventuelle du schéma corporel.Tout d’abord, nous avons testé si la distorsion morphologique du schéma corporel rapportée récemment dans l’anorexie mentale avait un retentissement sur la locomotion des patientes, dans une tâche de passabilité d’ouvertures (Etude 1). Les patientes ont effectivement tourné leurs épaules pour des largeurs d’ouvertures qui, compte tenu de leur nouvelle morphologie, ne nécessitaient pas une telle contorsion. Des comportements moteurs identiques ont été observés chez une patiente ayant perdu massivement et rapidement du poids, mais sans souffrir d’anorexie mentale (Etude 2). Ces résultats dans leur ensemble soulignent la rigidité du schéma corporel face à des changements corporels majeurs, ainsi que son incidence forte sur le comportement moteur dans l’anorexie mentale.Dans un deuxième temps, nous avons induit chez le sujet sain, grâce au paradigme miroir, souvent utilisé en réadaptation motrice, une distorsion entre schéma corporel et segments corporels, afin d’en évaluer les conséquences sur le comportement moteur volontaire (coordination bimanuelle, Etude 3) et involontaire (post-effet moteur, Etude 4). Les résultats de nos études font apparaître que la modulation des comportements moteurs dans le paradigme miroir serait plus liée aux afférences proprioceptives du bras face au miroir ou encore à une meilleure répartition des processus attentionnels, plutôt qu’à la distorsion du schéma corporel via le miroir.Enfin, nous avons testé si les comportements moteurs, ou tout du moins l’intention motrice à l’origine, pouvaient en retour moduler le schéma corporel et le sens du mouvement (Etude 5). Les illusions de mouvement induites dans le paradigme miroir ont bien été modulées selon que l’intention motrice du bras soumis à l’illusion soit congruente ou non avec le sens du mouvement illusoire généré.Compte tenu de l’implication de l’intention motrice dans la mise à jour du schéma corporel, nous suggérons que la prise en charge des troubles du schéma corporel (e.g. dans l’anorexie mentale), souvent basée sur une réadaptation visuelle de la représentation du corps, devrait être complétée par une remédiation sensori-motrice.Mots clefs : schéma corporel, comportement moteur, anorexie mentale, paradigme miroir, kinesthésie / The body schema is an internal and dynamic representation of the body, of the relative positions of body parts, but also of their metrics. It is supposed to be the support for motor behavior to develop appropriately. The main purpose of this doctoral work was to better assess this entanglement between body schema and motor behaviors. Specifically, we sought to evaluate how different motor behaviors are affected by distortions of the body schema, and conversely how the body schema could be modulated by motor behaviors.First, we tested whether the distortion between body schema and body morphology, recently reported in the anorexia nervosa patients, had an impact on their motor behaviors during a locomotion task of door crossing (Study 1). Results show that these patients are actually turning their shoulders for door widths which, given their body morphology, do not require such a contortion. Similar motor behaviors were observed on a patient who lost weight massively and quickly, without suffering from anorexia nervosa (Study 2). Altogether these results confirm the rigidity of body schema towards major body changes, as well as its significant impact on motor behavior in anorexia nervosa.In the second part of this work, we sought to experimentally induce a visual distortion between body schema and segmental positions in healthy subjects, with a mirror paradigm, usually used as therapeutic tool, and to assess the implications for a voluntary motor behavior (bimanual coordination task - Study 3) and an involuntary one (post-contraction response- Study 4). These results show that modulation on motor behaviors is more related to proprioceptive inputs from one arm facing the mirror or better allocation of attention, rather than distortions of the body schema and mirror itself.Finally, our last aim was to test whether the motor behavior, or at least the original motor intention, could in turn modulate the body schema (Study 5). Our results revealed that illusions of movement induced in the mirror paradigm were regulated by whether the participant conducted a motor intention, with the arm subject to the illusion, that was congruent or not with the induced illusory motion.Given the involvement of motor intention in updating the body schema, we suggest that the treatment of body schema disorders (e.g. anorexia nervosa), often based on a visual rehabilitation of the body representation, should be supplemented by a sensorimotor remediation.Keywords: body schema, motor behavior, anorexia nervosa, mirror paradigm, kinesthesia
368

Porovnání výtěžnosti kapra obecného (Cyprinus carpio) dle typu ošupení / Comparison proportion of Cyprinus carpio according to scale

ŠIKOVÁ, Jana January 2014 (has links)
The aim of the study was to compare the yield of scaly carp and mirror carp, two major representatives of the common carp (Cyprinus carpio), predominantly bred in the Czech Republic. The yield comparisons were performed in a newly created company store, where it was important to assess the suitability of fish for different products. A partial objective was, through a questionnaire survey, to determine the popularity and frequency of the consumption of carp. Finally, the intensity of individual forms of carp was monitored. The experiment was conducted in the years 2012-2013 during the four seasons spring, summer, autumn and after relaying. The evaluation took place for two types of carp, the mirror carp and the scaly carp. Another reference subject was two ponds, the naturally fed Vrbský Pond and the feeding pond Musik. Both carp are characterized by distinct developmental and life cycles. The mirror carp, the body structure of which is smaller than the scaly carp, demonstrated a higher yield in all monitored aspects at the end of the evaluation. At the same time, the fillet yield of both representatives achieved similar values and ranged from about 43-48%. The carp from the feeding pond Musik gave a surprising result, where a lower yield was expected due to the lower amount of plankton and zoobenthos, a natural food for fish. During the monitored period, the highest yield was recorded in the period after relaying, while the lowest yield in the spring, due to the selected increased fish stock for the given year.
369

Porovnání biometrických a výtěžnostních ukazatelů kříženců kapra obecného s využitím dvou různých linií Amurského lysce / Comparison of biometrical and slaughtering indicators of crossbreeds of common carp with using two different breeds of Amur mirror carp

PRCHAL, Martin January 2013 (has links)
The objective of this thesis was to compare biometrical and slaughtering indicators of common carp crossbreeds using two different breeds of Amur mirror carp in performance testing. We applied top-crossing for the test establishment, using the Hungarian mirror carp (M2) on the maternal position. Males of Hungarian mirror carp (for the production of purebreed), Northern mirror carp (M72) and two breeds of Amur mirror carp (ALP ? bred in Pohořelice, ALV ? bred in Vodňany) were crossed on this breed and hybrids of scaly phenotype between Ropsha (ROP) and Tata carp (TAT) were used as a control group. The performance testing started in ponds (in the total of five localities) in the semi ? intensive way of management by releasing yolk sac fry (K0) and its subsequent rearing to the market size (K3). The performance test was completed in ponds after the third year of testing and the tested groups of fish were evaluated for biometrical and slaughtering indicators. In the overall evaluation of the edible parts of the body (processed body and fillets) by the ANCOVA method was not found a statistical difference among the mirror tested groups of fish. The only exception was the proportion of fillets without skin, which was significantly higher in the hybrid M2 x ALP than in breed M2, therefore I would not recommend this breed (M2) to commercial breeding. When comparing my results with other publications, the hybrid M2 x M72 could be used for commercial breeding together with the two hybrids of Amur mirror carp, who not only achieve high yield of edible parts of the body, but also the earlier tests confirmed higher growth, better survival and resistance to the KHV virus.
370

Light and single-molecule coupling in plasmonic nanogaps

Chikkaraddy, Rohit January 2018 (has links)
Plasmonic cavities confine optical fields at metal-dielectric interfaces via collective charge oscillations of free electrons within metals termed surface plasmon polaritons (SPPs). SPPs are confined in nanometre gaps formed between two metallic surfaces which creates an optical resonance. This optical resonance of the system is controlled by the geometry and the material of the nanogap. The focus of this work is to understand and utilize these confined optical modes to probe and manipulate the dynamics of single-molecules at room temperature. In this thesis, nanogap cavities are constructed by placing nanoparticles on top of a metal-film separated by molecular spacers. Such nanogaps act as cavities with confined optical fields in the gap. Precise position and orientation of single-molecules in the gap is obtained by supramolecular guest-host assembly and DNA origami breadboards. The interaction of light and single-molecules is studied in two different regimes of interaction strength. In the perturbative regime molecular light emission from electronic and vibrational states is strongly enhanced and therefore is used for the detection of single-molecules. In this regime the energy states remain unaltered, however profound effects emerge when the gap size is reduced to < 1 nm. New hybridized energy states which are half-light and half-matter are then formed. Dispersion of these energies is studied by tuning the cavity resonance across the molecular resonance, revealing the anti-crossing signature of a strongly coupled system. This dressing of molecules with light results in the modification of photochemistry and photophysics of single-molecules, opening up the exploration of complex natural processes such as photosynthesis and the possibility to manipulate chemical bonds.

Page generated in 0.0548 seconds