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  • 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.
1

Etude biomécanique de la distraction ostéogénique et de sa mise en oeuvre en chirurgie maxillofaciale / Biomechanical study of the distraction ostéogénésis and its application in maxillofacial surgery

Dubois, Guillaume 18 November 2008 (has links)
La distraction ostéogénique est une technique chirurgicale visant à reconstruire les defects osseux ou à allonger les os du corps humain. Elle met à profit la capacité du tissu osseux à se régénérer sous une stimulation mécanique appropriée. L'objectif général de ce travail est l'optimisation des moyens permettant de mettre en œuvre ce procédé en chirurgie maxillo-faciale. Plus particulièrement, il est focalisé sur le Distracteur Ostéogénique Sur mesure (DEOS) de la société OBL et les protocoles associés. Pour cela, un modèle micromécanique de guérison osseuse a été développé afin de permettre de simuler numériquement les transformations mécano-biologiques se produisant au sein du régénérat de distraction. Après son implémentation dans une routine de calcul, cette approche a été appliquée à un modèle simplifié de la distraction. Elle a ainsi pu permettre de reproduire des phénomènes encore jamais décrits numériquement et d'établir des propositions pratiques pour l'amélioration des protocoles et des dispositifs de distraction. D'autre part, la force de transport osseux lors de l'utilisation du DEOS a été étudiée. Une méthode originale de mesure de cet effort a été développée en tenant compte des spécificités de l'expérimentation en biomécanique. Une campagne d'essais a alors été menée avec la participation de deux patients bénéficiant du DEOS pour constituer une base de résultats qui a ensuite été analysée. Enfin, l'ensemble des résultats obtenus a servi à l'optimisation des caractéristiques du DEOS selon les souhaits des cliniciens et des patients. Elle a abouti à des avancées notables sur les paramètres essentiels que sont sa masse, son encombrement et sa fonctionnalité / Distraction osteogenesis is a process used to restore bone defects or to lengthen bone segments of the human body. It takes advantage of bone tissue ability to regenerate itself under an appropriate mechanical stimulation. The goal of this work is the optimisation of the ways this technique is implemented in maxillofacial surgery. A special focus has been done on the DEOS device from OBL company and on the associated protocols. In order to simulate mechanobiological changes happening in the distraction regenerate a micromechanical bone healing model was developed. After it was implemented in a computational routine, this approach was applied to a simplified bone distraction model. It allowed the numerical investigations of phenomena never simulated before. It also permitted to propose practical improvements of distraction protocols and devices. Moreover, the bone distraction force when using the DEOS was studied. An original method for the measurement of this force was set up taking into account restrictions of biomechanical tests. An experimental campaign was led with two patients benefiting from the DEOS. A database was then created and analysed. Finally, all the results obtained were used to optimise the DEOS up to clinicians and patients wishes. This has come to noticeable improvements of essential parameters as mass, size and practicality of this device
2

Visual demand and the introduction of advanced driver information systems into road vehicles

Lansdown, Terry C. January 1996 (has links)
This thesis contains six studies investigating the impact of advanced in-vehicle information systems on the visual demands of the driver. The experiments, while self-contained were conceived to relate together in a cohesive manner. The first study investigated the reliability of visual behaviour assessment. Video tape records from experimental trials were analysed post-hoc. Significant test/retest correlations were obtained. Experiment two considered the visual demands of the driving task without intervention from new technologies. Results from road trials using an instrumented vehicle suggested changes in the subject's visual scanning which could be related to the roadway environment (i.e., rural, urban and motorway driving). In experiment three the effects of the introduction of a driver information system were assessed using a congestion warning device on public roads. System use resulted in significantly greater: subjective mental workload, glance duration and frequency, and percentage time (eyes) away from the forward view; than the in-car entertainment system, or the control (normal driving). Experiment four replicated experiment three in a fixed base driving simulator. It aimed to establish the value of the simulator for the assessment of driver visual demand. The same significant differences presented in the road trial were observed in the simulation study. In the penultimate study, opportunities for the reduction of driver visual demand were investigated. The subjects were presented with: visual, auditory or visual and auditory route guidance information. Results suggest use of auditory information to supplement visual displays significantly reduces visual demand on the driver. The final study considered the effect of information availability on the distribution of visual scanning. Driver control of in-vehicle information presentation enabled self-determination of visual scanning strategies. Information system control of information presentation was found to disrupt the driver's visual checking. The interface design was shown to force the driver to adopt different visual scanning strategies. The contribution of the experimental work to the assessment of driver visual demand is discussed and the relationships between the experiments explored.
3

The differential effects of mental fatigue and alcohol on selective attention /

Bloesch, Emily Keller. January 2008 (has links)
Thesis (M.A.)--Western Kentucky University, 2008. / Includes bibliographical references (leaves 35-40).
4

Presenteeism a comparative analysis /

O'Donnell, James E., January 2009 (has links)
Thesis (M.S.)--University of Massachusetts Amherst, 2009. / Open access. Includes bibliographical references (p. 95-100).
5

Mémoire à court terme chez les personnes qui souffrent de schizophrénie : étude du traitement de l'information spatiale et de la résistance à la distraction /

Cellard, Caroline. January 2004 (has links)
Thèse (M.Ps.)--Université Laval, 2004. / Bibliogr.: f. 54-59. Publié aussi en version électronique.
6

Effect of acceptance, distraction, and sensory monitoring on acute pain and attention

Kyle, Brandon N. January 2007 (has links)
Thesis (M.S.)--West Virginia University, 2007. / Title from document title page. Document formatted into pages; contains vii, 105 p. : ill. Includes abstract. Includes bibliographical references (p. 51-63).
7

INVESTIGATIONS OF DISTRACTOR STRENGTH ON ATTENTIONAL PROCESSING IN A MIXED BLOCK DESIGN

Unknown Date (has links)
In everyday life, we come across visual distractors such as crossing the street or driving down the highway, but what properties of distractors determine whether they will affect cognitive processing? Relatively little is known about how the strength of a distractor or changing it over time affects the ability to deploy attention. Previous studies have shown that suprathreshold stimuli interfere more in the Simon Effect than near threshold stimuli. However, it is unknown whether this effect is due simply to motor inhibition or generalizes to tasks without a motor component. To test the generalizability of this effect, an attentional blink task was presented in which a coherent motion stimulus surrounded a rapid serial visual presentation stream. The study demonstrated that the highest coherence condition presented first had the greatest effect on performance accuracy. This is suggestive of a diffused attentional state. / Includes bibliography. / Thesis (M.A.)--Florida Atlantic University, 2021. / FAU Electronic Theses and Dissertations Collection
8

Pre-clinical evaluation of the forces during limb lengthening using manual and automated devices

Sinclair, Rhona Ann January 2011 (has links)
Limb lengthening procedures use fixation devices to extend the constantly regenerating bone and surrounding soft tissues. Automated devices have been developed that aim to provide a more gradual tissue extension, resulting in better quality of treatment for the patient. Benefits include pain reduction and probable enhanced tissue outcomes. The development of one such new smart lengthening device is described. An integrated numerical model of tissue mechanics during lengthening is presented. It represents the mechanical environment in which the devices extend. The mechanism of the automated device is also modelled using Matlab software and validation was achieved through experimental testing. Validation of the tissue model includes the design of an experimental hydraulic system with the ability to control the peak loads and relaxation over time. A simplified mechanobiological model for the longer term healing effects is proposed. Calibration of the tissue model to clinical data allows for direct comparison of the load and extension of identical tissues, one being lengthened by a traditional device, the other an automated device. This simulation can be extended to include a range of lengthening rates and frequencies of distraction alongside various patient dependent tissue properties. The models also provide the opportunity to assess the effects of iterative changes to the device parameters (such as stiffness) on its performance as well as analyse the effect that these changes have on tissue extension and loading. Use of these models to optimise the device design alongside optimisation of the extension regime can result in improved device design and consequently improved patient outcomes.
9

Next-Generation Smart Cars: Towards a More Intelligent Interactive Infotainment System

January 2017 (has links)
abstract: Today, in a world of automation, the impact of Artificial Intelligence can be seen in every aspect of our lives. Starting from smart homes to self-driving cars everything is run using intelligent, adaptive technologies. In this thesis, an attempt is made to analyze the correlation between driving quality and its impact on the use of car infotainment system and vice versa and hence the driver distraction. Various internal and external driving factors have been identified to understand the dependency and seriousness of driver distraction caused due to the car infotainment system. We have seen a number UI/UX changes, speech recognition advancements in cars to reduce distraction. But reducing the number of casualties on road is still a persisting problem in hand as the cognitive load on the driver is considered to be one of the primary reasons for distractions leading to casualties. In this research, a pathway has been provided to move towards building an artificially intelligent, adaptive and interactive infotainment which is trained to behave differently by analyzing the driving quality without the intervention of the driver. The aim is to not only shift focus of the driver from screen to street view, but to also change the inherent behavior of the infotainment system based on the driving statistics at that point in time without the need for driver intervention. / Dissertation/Thesis / Masters Thesis Software Engineering 2017
10

Surface structure and saccadic control

Jardine, Nicole 01 May 2018 (has links)
Saccadic eye movements are guided by attention. Indeed, some saccade trajectory effects serve as an index the attentional strength of visual objects in the map of visual space used to plan a saccade. One approach to understanding saccade planning relies on simple tasks in sparse displays (containing a single target and distractor object) to develop neurophysiologically plausible models of saccade behavior. Under tightly controlled conditions, saccade trajectories can be well predicted by representing displays of objects with simple visual features and their relative salience. But the world in which the saccade system typically operates is not sparse, and observer eye movements are guided by more than just salience. As such, another approach has been to examine saccadic behavior in complex scenes and complicated goals. Such scene context can drastically affect saccades in ways that are not well predicted by a context-free and expectation-free representation of visual salience. This dissertation starts to bridge this gap between these literatures by focusing on object surfaces. Covert shifts of attention operate on representations informed not just by stimulus salience and location-based expectations, but also by the perceptual organization of object surfaces. Covert attention can be guided by surface context, such that targets and distractors are processed differently as a function of whether they are on the same or different surface. These effects are fragile, however, and have previously only been demonstrated in relatively engaging tasks and with strong perceptions of objecthood. The present work tested the strength of the relationship between attention and saccades by testing whether surface context guides orienting eye movements. Observers made saccades to objects that could be organized with different surface structure. In four experiments (Chapters 2 and 3) I found no evidence that the saccade map encoded surface context. But in two experiments (Chapters 4 and 5) I demonstrate saccade trajectories are sensitive to surface context, independently of low or high task engagement. This demonstrates that object surface-based representations are not necessarily fragile and can affect the oculomotor map even for simple saccadic orienting for which the surface is task-irrelevant. This lends evidence to the theory that the nature of the representation of vision is one of object surfaces, and suggests that the strength of object encoding is stronger than has been previously demonstrated.

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