Timeliness in delivering packets for delay-sensitive applications is an important QoS (Quality of Service) measure in many systems, notably those that need to provide real-time performance. In such systems, if delay-sensitive traffic is delivered to the destination beyond the deadline, then the packets will be rendered useless and dropped after received at the destination. Bandwidth that is already scarce and shared between network nodes is wasted in relaying these expired packets. This thesis proposes that a deterministic per-hop delay can be achieved by using a dynamic queue threshold concept to bound delay of each node. A deterministic per-hop delay is a key component in guaranteeing a deterministic end-to-end delay. The research aims to develop a generic approach that can constrain network delay of delay-sensitive traffic in a dynamic network. Two adaptive queue management schemes, namely, DTH (Dynamic THreshold) and ADTH (Adaptive DTH) are proposed to realize the claim. Both DTH and ADTH use the dynamic threshold concept to constrain queuing delay so that bounded average queuing delay can be achieved for the former and bounded maximum nodal delay can be achieved for the latter. DTH is an analytical approach, which uses queuing theory with superposition of N MMBP-2 (Markov Modulated Bernoulli Process) arrival processes to obtain a mapping relationship between average queuing delay and an appropriate queuing threshold, for queue management. While ADTH is an measurement-based algorithmic approach that can respond to the time-varying link quality and network dynamics in wireless ad hoc networks to constrain network delay. It manages a queue based on system performance measurements and feedback of error measured against a target delay requirement. Numerical analysis and Matlab simulation have been carried out for DTH for the purposes of validation and performance analysis. While ADTH has been evaluated in NS-2 simulation and implemented in a multi-hop wireless ad hoc network testbed for performance analysis. Results show that DTH and ADTH can constrain network delay based on the specified delay requirements, with higher packet loss as a trade-off.

Magneto-sensitive elastomers (MSEs) establish a special class of smart materials, which are able to change their shape and mechanical behavior under external magnetic field. Nowadays, MSEs are one of the most perspective smart materials, since they can be used for design of functionally integrated lightweight structures in sensors, robotics, actuators and damper applications. MSEs typically consist of micron-sized magnetizable particles (e.g. carbonyl iron) dispersed within a non-magnetic elastomeric matrix. The spatial distribution of magnetic particles in MSEs can be either isotropic or anisotropic, depending on whether they have been aligned by an applied magnetic field before the cross-linking of the polymer. Depending on the magnetic properties of the particles, their shape, size and spatial distribution, the MSEs can exhibit different mechanical behavior. Most experimental studies show that MSEs with isotropic distribution of magnetic particles demonstrate a uniaxial expansion along the magnetic field. On the other side, it was shown experimentally that MSEs with anisotropic particle distributions demonstrate a uniaxial contraction along the magnetic field. Also, the experimental works show that the shear moduli of MSEs increase with increasing strength of the magnetic field and depend on the magnetic properties, volume fraction and spatial distribution of particles. Different analytical approaches were used in theoretical studies of the mechanical behavior of MSEs. They can be roughly classified as phenomenological, continuum-mechanics and microscopic approaches. In the phenomenological approaches, the expansion into a series of the shear modulus as a function of the strength of the magnetic field has been proposed, the coefficients of the expansion being considered as phenomenological fitting parameters. In the continuum-mechanics approach, an MSE is considered as continuous magnetic media. It allows us to determine the shape and the change in volume of a spherical MSE sample, placed in a uniform magnetic field. However, this approach is restricted to homogeneous particle distributions. The microscopic approach has a clear advantage, while a discrete particle distribution and pair-wise interactions between induced magnetic dipoles can be considered explicitly. The aim of the present work is to develop a microscopic theory, which properly describes the mechanical behavior of MSEs in the external magnetic field. The theory takes a microscopic structure, finite shape of the samples and magneto-mechanical coupling between particle positions and sample deformation explicitly into account.

This study investigates the relationship between firm performance and institutionalownership in Sweden. This study contributes to the ongoing debate between researchersregarding the potential benefit of institutional owners through increased monitoringcapabilities. A panel data analysis and a fixed effects model estimated with generalized leastsquares is utilized to investigate the relationship between performance and ownership structure,controlling for firm size, foreign ownership, leverage and return on equity. While having astrong theoretical foundation no correlation is found between institutional ownership and firmperformance. This is true even when institutional owners are further divided into pressureresistantand pressure-sensitive owners. This study indicates that institutional ownership has noimpact on firm performance. These findings are consistent with similar studies performed inother Nordic countries. / Master thesis

The work presented in this thesis is concerned with development of spectroscopic detection methods based on absorption spectroscopy using semiconductor lasers, with particular ref- erence to the field of medical diagnostics through breath analysis. The first part of this thesis deals with the design and testing of a prototype analyser for simultaneous monitoring of the exchange gases O₂ , CO₂ and H₂O in breath. The aim of this analyser is to provide information required to monitor respiration, with potential use in intensive care monitoring or during anaesthesia. The relatively high concentrations of these gases in breath and read- ily available diode laser sources make detection in the near-infrared (NIR) ideal. However, the relatively weakly absorbing A-band O₂ transitions at 760 nm require the application of a sensitive spectroscopic method, cavity enhanced absorption spectroscopy (CEAS). In contrast, CO₂ and H₂O are monitored using direct single pass absorption spectroscopy, with transitions arising from the 2ν₁ + ν₃ band at 2 μm and ν₁ + ν₃ band at 1.3 μm, respectively. It has been demonstrated that these gases can be detected simultaneously over a short pathlength (2.74 - 4 cm) in the respiratory flow by combining various spectroscopic methodologies and real-time data analysis. This analyser is shown to offer a viable alter- native for monitoring respiration, exhibiting absolute detection limits of changes of 0.26 % O₂ , 0.02 % CO₂ and 0.003 % H₂O with a 10 ms time resolution, which are comparable to current mass spectrometry based methods, but without their inherent delays. Following this, investigations into the detection of the main gas constituents in breath in the NIR employing noise-reduction modulation based spectroscopic techniques, namely wavelength and frequency modulation (WMS and FMS respectively) are also reported. The described WMS studies on water at 1.37 μm provide a demonstration of conventional WMS detection, as well as a “proof-of-principle” example of a relatively new approach to calibrating the non-absolute information obtained from a WMS absorption signal. Typically WMS spectra are calibrated using mixtures of known gas concentrations or an absolute direct absorption spectrum where possible. In this work however, a self-calibrating method, the phasor decomposition method (PDM), is employed and the returned concentration from this calibration is compared to direct absorption measurement. From this, the calculated concentration using the PDM is found to differ by 9 % from the concentration value obtained by direct absorption, providing an alternative method of calibration for when direct absorption measurements are not possible. The use of FMS in the NIR is also demonstrated as a potential alternative to CEAS for monitoring O₂ at 760 nm. FMS detection is performed on atmospherically broadened O₂ and a time-normalised α_min(t) of 2.45 ×10⁻⁶ cm⁻¹ s^1/2 is obtained, which is two orders of magnitude less sensitive than the value of α_min(t) = 2.35 ×10⁻⁸ cm⁻¹ s^1/2 obtained with CEAS. This combined with the experimental requirements of an FMS system, make its use for detection of O₂ a less practicable option compared to CEAS for real-time breath analysis. The latter work in this thesis involves a change in focus to detection of trace gases in breath in the mid-infrared (MIR). The move of spectroscopic detection to the MIR exploits the larger absorption cross-sections available in this region, and to achieve this, a relatively new form of semiconductor laser, the quantum cascade laser (QCL) is used. The design of a continuous wave QCL spectrometer at 8 μm and its operating characteristics are demon- strated and improvements in its performances are also discussed. This QCL system is then utilised to demonstrate the potential of monitoring species in breath, namely the narrow- band absorber methane and the broadband absorber acetone, taking into consideration the potential interference from other absorbing species in breath and the different spectroscopic characteristics exhibited by these molecules. Finally, the potential to further improve the sensitive detection of trace gases in breath in the MIR is also investigated with studies on the use of CEAS and multipass cells. In this work, the molecule of interest is the biomarker OCS, using transitions of the 2ν₂ band at 1031 cm⁻¹ , that are probed using a 10 μm QCL. The application of CEAS in the MIR is not as well developed as in the NIR, and the experimental consequences of using optical cavities at these wavelengths, where equipment tends to be more limited, are investigated and sensitivities discussed in the context of other literature. The experimental procedure of optimising a cavity for CEAS using the off-axis alignment method is also studied in detail, as well as the addition of WMS to further improve the signal quality. An effective absorption pathlength of ∼ 100 m was achieved in the cavity, with a bandwidth reduced α_min(BW) of 1.7 ×10⁻⁷ cm⁻¹ Hz^−1/2 using WMS CEAS achieved. With the poorer quality optics and limitations in equipment in the MIR for CEAS experiments, the use of a multipass cell, a 238 m Herriott cell, is also investigated as an alternative to the use of an optical cavity at 10 μm. Detection of OCS using direct absorption and WMS is demonstrated in the Herriott cell, achieving α_min(BW) = 2.03×10⁻⁸ cm⁻¹ Hz^−1/2 using WMS. This shows an improvement in sensitivity compared to WMS CEAS, and also shows the potential for future work on biomarker detection, as it approaches the ∼ ppb levels required for breath analysis.

Chez plusieurs espèces, les neurones auditifs sensibles à la durée de la stimulation sont présents au niveau des collicules inférieurs. Toutefois, le décours temporel de leur développement fonctionnel est inconnu. Étant donné que le collicule supérieur est l’un des principaux relais sous-cortical impliqué dans l’intégration des stimuli audio-visuels, nous voulons déterminer si le collicule supérieur du rat contient de tels neurones et s’ils sont sensibles et sélectifs à différentes durées de stimulation auditive. De plus, l'originalité de cette étude est de déterminer les étapes de leur maturation fonctionnelle. Des enregistrements neuronaux unitaires et extra-cellulaires sont effectués dans le collicule supérieur de rats juvéniles (P15-P18, P21-P24, P27-P30) et adultes anesthésiés. La sensibilité à la durée est déterminée lors de la présentation de bruits gaussiens (2-10 dB SPL au-dessus du seuil) de durées variables (3-100 ms). Seulement un faible pourcentage des neurones du collicule supérieur est de type passe-bande (3-9% des neurones parmi les ratons et 20% chez les rats adultes). Une différence significative de la distribution entre les différents types de neurones auditifs sensibles à la durée est présente au cours du développement: les neurones de type passe-haut (63-75%) sont présents en majorité chez les groupes juvéniles alors que 43% des neurones sont de type insensible à la durée de la stimulation auditive chez les rats adultes. Ces résultats montrent qu’une population importante de neurones auditifs du collicule supérieur du rat est sensible à la durée des signaux sonores et qu’un développement fonctionnel important survient au cours du premier mois postnatal. / In many species, duration-sensitive neurons which could possibly analyse species-specific vocalizations are encountered in the inferior colliculus. However, their postnatal development is unknown. Since the superior colliculus is one of the most important subcortical relay implicated in the audiovisual integration, we sought to gain insight on whether the SC of the rat contains such neurons and, if so, whether they are sensitive and selective to duration. Furthermore, the originality of this study is to determine their fonctional maturation. Extracellular single-unit recordings were assessed in the deep layers of the superior colliculus of anesthetized rats throughout postnatal days (P15 – P18, P21 – P24, P27 – P30) and at adulthood. Gaussian noises of different durations (3-100 ms) were presented in free-field in pseudo-random order (2 – 10 dB SPL above threshold). Only few neurons are band-pass: about 3 – 9% across the different age groups (P15 – P30) and 20 % in adults. Thus, in terms of categories of duration-sensitive neurons profiles, a significant difference was evident across postnatal development: long-pass (63-75%) neurons were mostly encountered in the different groups of pups relative to all-pass (43%) in adult rats. These results demonstrate that a large population of neurons in the superior colliculus of the rat is sensitive to noise durations and that important development changes occur during postnatal maturation.

Les micelles complexes de polyions, ou « micelles PIC », formées par interaction électrostatique entre un copolymère à blocs double hydrophile neutre-ionique (DHBC) et un homopolyélectrolyte de charge opposée au DHBC possèdent des propriétés particulièrement intéressantes : solubilité des polyélectrolytes dans l'eau, stabilité des micelles, contrôle de l'association/dissociation micellaire par divers stimuli (pH, force ionique, irradiation lumineuse…). Dans cette thèse, les propriétés physico-chimiques des micelles PIC de type DHBC neutre-cationique/homopolymère anionique et DHBC neutre-anionique/homopolyélectrolyte cationique ont été étudiées en solution aqueuse en vue de leur utilisation comme agent structurant des matériaux siliciques organisés à l'échelle nanométrique. La gamme de pH de formation des micelles PIC, la concentration micellaire critique et le nombre d'agrégation des micelles ont été déterminés pour chacun des systèmes étudiés. Nous avons montré que la formation des micelles suit un mécanisme coopératif qui dépend de la taille de l'homopolymère. Par ailleurs, nous avons proposé une voie originale de formation des micelles PIC photoinduite, basée sur une modification du pH suite à l'irradiation d'une molécule photochrome. Les études concernant l'utilisation des micelles PIC comme agent structurant des matériaux nous ont permis de montrer que la morphologie (nanoparticulaire, massif) et la structure des matériaux (lamellaire, vermiculaire) peuvent être contrôlés par divers paramètres, tels que la concentration en masse du système DHBC/homopolyélectrolyte/précurseur de silice, la teneur en précurseur de silice et le rapport entre les fonctions cationique et anionique des polyélectrolytes. Le lavage des matériaux sous des conditions douces (à l'eau) permet de récupérer l'agent structurant. / Polyion complex micelles, or "PIC micelles", formed by electrostatic interaction between a neutral-ionic double hydrophilic block copolymer (DHBC) and an oppositely charged homopolyelectrolyte possess interesting properties: solubility of the polyelectrolytes in water, stability of micelles, control of the micellar association / dissociation by various stimuli (pH, ionic strength, light irradiation ...). In this thesis, the physico-chemical properties of PIC micelles of neutral-cationic DHBC/ anionic homopolymer and neutral-anionic DHBC/cationic homopolymer were studied in aqueous solution for use as structuring agents of silica-based organized nanomaterials. The pH range of PIC micelle formation, the critical micelle concentration and aggregation number of micelles were determined for each studied system. We have shown that the formation of micelles follows a cooperative mechanism which depends on the size of the homopolymer. Furthermore, we proposed an original way of photoinduced PIC micelle formation, based on a pH change after irradiation of a photochromic molecule. The studies on the PIC micelles as structuring agents of materials have shown that the morphology (nanoparticular, bulk) and the material structure (lamellar, vermicular) can be controlled by various parameters, such as the mass concentration of the DHBC / homopolyelectrolyte / silica precursor system, the content of the silica precursor and the ratio between the functions of the cationic and anionic polyelectrolytes. Finally, the template was removed by washing the hybrid materials under soft conditions in water.

Nous avons analysé l'activité de population au sein du cortex visuel primaire en vue de comprendre (i) les mécanismes mis en jeu lors de l'intégration de l'information visuelle suite à un mouvement oculaire, et inversement (ii) de l'influence du traitement effectué au niveau de V1 sur la génération d'un mouvement oculaire.1. Nous avons enregistré des saccades de fixation, et mis en relation, essai par essai, ces mouvements avec la représentation de la position d'un stimulus local dans V1. Après une saccade de fixation, l'activité se déplace de façon cohérente dans V1. Le décours temporel des réponses au niveau des foyers pre- et post-saccadiques montre une dynamique biphasique. La taille du foyer d'activité augmente. Nous proposons que le comportement des populations de neurones s'explique par deux phénomènes principaux : (i) La réponse suppressive précoce attribuable à la décharge corollaire (ii) de connections latérales qui réactiveraient le foyer pre-saccadique.2. Nous avons enregistré l'OFR, et cherché à savoir si la réponse de V1 l'influençait. Les latences VSD précèdent les latences OFR. Il n'existe pas de corrélation à l'essai unique. Nous avons montré que la force et la dynamique des réponses de V1 n'étaient pas prédictives de l'OFR. La distance de la périphérie à un effet sur la réponse VSD, mais pas sur l'OFR. La dynamique de propagation de cette suppression, nous avons montré deux phases : une précoce sur l'ensemble de la carte, et une plus périphérique tardive. Nous proposons que la suppression précoce soit originaire de projections en retour de structures comme MT et MST, alors que la suppression plus lente s'explique par les connections horizontales. / We analyzed population activity in V1 to understand (i) the consequence of eye movements on integration of visual information, and (ii) the influence of the processing performed at the level of V1 on the generation of eye movements.1. We recorded fixational saccades, relating, trial-by-trial, these eye movements with the representation of the position of a local stimulus in V1. After a fixational saccade, activity moves consistently in V1. However, the time-course of responses display a biphasic dynamic. This results in a global increase of the extent of cortical activity representing the local stimulus. We propose that the behavior of populations of neurons studied is explained by the contribution of two main phenomena: (i) an early suppressive response that could be attributed to the corollary discharge and (ii) the lateral connections generating lateral interactions between pre and post-saccadic lci of activity.2. We recorded the ocular following response, determining whether the response of V1 influences the oculomotor response. We studied the contrast response function of the population V1 activity and the OFR. The dynamics of CRF for a local stimulus are similar and shifted in time. We found no correlations between the single trial latencies between V1 and the OFR. At the chosen scale, surround suppression was found to be distance-dependent only in V1. The dynamics of the surround suppression shows two phases: an early suppression present over a wide cortical area, and a later peripheral spread. We propose that the early surround suppression originates from feedback from MT and MST, while the later is explained by the horizontal connections.

Derrière l’apparent consensus de l’application du registre de la durabilité à la ville, notre recherche contribue à analyser, dans une perspective critique, ce que recouvre la locution de ville durable dans le champ de l’urbanisme. Nos investigations reposent tout d’abord sur l’étude des modalités d’émergence de l’expression, conjuguée à l’examen du traitement dont la notion fait l’objet dans la littérature scientifique et professionnelle. Nourrie du rapport dressé entre méditerranéité et pensée complexe (MORIN 1999), l’approche est ensuite incarnée au sein d’une ville méditerranéenne : Marseille. Elle se fonde alors sur l’analyse des représentations que les acteurs en charge de la fabrique urbaine se font de la ville durable, éclairant ainsi ce qui fonde leurs actions dans ce domaine. L’enjeu réside enfin dans la mise en regard de l’ensemble avec les conséquences matérielles, socio-spatiales et vécues des productions effectives. Celle-ci s'opère à travers un cheminement exploratoire sensible ponctué d’observations et de récits d’habitants, au sein d’un secteur dont les principes de réalisation sont rattachés à l’idée de ville durable. Notre parcours de thèse montre ainsi comment, exogène aux sphères de l’urbanisme, la notion de ville durable ne constitue pas un cadre suffisamment émancipateur et robuste pour permettre aux acteurs du champ de parvenir à un renouvellement des savoirs ni de s’affranchir des contraintes et tendances lourdes qui pèsent sur la fabrique urbaine. Il propose, ce faisant, une démarche écologique permettant d’explorer ce/ceux sur quoi/qui pourraient reposer la ou plutôt les durabilités urbaines et comment. / Whilst there seems to be a consensus on the feasibility of applying sustainability thinking to town and city development, our research contributes to the critical understanding of the notion of a sustainable city within the field of urban planning. We will begin with a study of the modalities of the emergence of this term, combining it with an analysis of the ways in which the notion is used in professional and scientific literature. Following on from the correspondence drawn between "méditerranéité" and complex thinking (MORIN 1999), our approach will then be embodied in the heart of a Mediterranean city : Marseille. Considering the mental pictures conjured up by the notion of sustainable city, we thus analyse the ways in which the elements of meaning previously highlighted are being used or not, interpreted, or even diverted, and how they influence decisions and actions. As the object of our work is the relationship between these and their material, socio-spatial and experiential impact, we then go on to conduct a sensitive exploration using observations and stories told by local residents within a sector in which actualisation principles are relating to the idea of sustainable city. This research shows, in the end, how the notion of sustainable city, which is exogenous to the domain of urban planning, does not offer a sufficiently emancipating or robust framework to allow the development of new “knowledge and know-how” or to outweigh the constraints and forceful trends that hinder the development of the town. This leads us to propose an "ecological" approach to explore what and whose contributions urban sustainability or rather sustainabilities might be built upon.

Cette recherche montre l’écart entre les intentions politiques et institutionnelles et les pratiques des professeurs des écoles, qui sont partielles et hétérogènes. Il existe une pluralité de points de vue sur la légitimité et la pertinence de l’enseignement laïque des faits religieux, qui demeure un objet scolaire discuté. Un pan de notre étude est consacré à l’analyse des pratiques de professeurs enseignant les faits religieux pour éduquer à la laïcité. Ceux-ci, en prenant en charge l’enseignement de questions vives, ont dû faire preuve d’ingéniosité pédagogique, se traduisant par des bricolages rendus nécessaires par la rareté des outils, le manque de formation et l’absence de préconisations institutionnelles quant aux savoirs intermédiaires adéquats. Si, globalement, leurs pratiques répondent aux objectifs principaux de l’enseignement des faits religieux, notamment éduquer à la laïcité, aborder ces sujets suppose un investissement personnel lourd, pour l’enseignant comme pour ses élèves, et renvoie chacun à ses systèmes de valeurs. Les principaux écueils relevés sont liés au respect de l’obligation de neutralité (difficulté à se représenter sa pertinence pédagogique, sa transposition). En l’absence d’outils et de formation dédiés, certains enseignants sont démunis. L’association ENQUÊTE a été créée en 2010 pour répondre à ce besoin. Elle souhaite contribuer à réduire l’écart entre les intentions institutionnelles favorables à l’enseignement des faits religieux dans le cadre d’une éducation à la laïcité et les pratiques des professeurs, via des formations et des outils, et aussi à promouvoir cet enseignement et cette "éducation à" auprès des acteurs politiques et institutionnels. / This research highlights a gap between political and institutional intentions, and practices of school teachers, which are partial and heterogeneous. There is a plurality of views about the legitimacy and relevance of teaching about religions and beliefs in a secular way, which is still a very much debated school subject. One part of this study is dedicated to the analysis of teachers' practices when teaching about religions and beliefs in order to educate to laicity. To address these sensitive education issues demands creativity. Because of a scarcity of tools, lack of training and very few institutional recommendations about adequate intermediate knowledge, teachers have had to cobble together their own teaching materials. Overall, their practices meet the main purposes of teaching about religions, especially to educate to laicity. Nonetheless, dealing with these subjects requires a heavy personal investment, for the teacher as well as for their students, and brings back each one to his own value systems. The main identified pitfalls are linked to the neutrality obligation : they find it difficult to represent their pedagogical relevance and to translate it into their teaching. Many teachers feel helpless when confronted to the lack of dedicated tools and training. ENQUÊTE is an association that was created in 2010 in order to address this issue. Its first objective is to contribute, via trainings and tools, to reducing the gap between institutional intentions that favour teaching about religions and beliefs – as part of the education to laicity – and teachers' practices. Its second goal is to promote this teaching among political and institutional actors.

M.Sc.(Occupational Therapy), Faculty of Health Sciences, University of the Witwatersrand, 2009 / Title: The agreement found between the sensory profiles of children 3-10 years and their parents Author: Elsje Geyser Promoter: Denise Franszen School: Therapeutic Sciences Faculty: Health Sciences Degree: MSc.OT Key Concepts: Sensory modulation dysfunction, sensory processing disorder, high threshold, low threshold, sensory profile, low registration behaviour, sensory seeking behaviour, sensory sensitive behaviour, sensation avoiding behaviour. In order to treat a child with sensory modulation disorder (SMD), the impact of SMD on the child’s occupational sphere should be taken into account. This includes the effect of SMD in the parent on the child’s development and behaviour. This study determined the probability of agreement between the parent and child’s sensory profiles. A quantitative, cross sectional study design established the sensory profiles of 81 children and their parents. Results indicated a moderate probability that a child with SMD may have a parent with SMD. A moderate to high probability existed for a parent with SMD to have a child with SMD. This supports the supposition that there is a hereditary component to SMD, with learned sedentary behavioural patterns. The treatment implications include considering the parent’s reaction to their own sensory thresholds and the influence this has on the child’s treatment and learnt behaviour.