Inflammation is an integral part of the body defense mechanism that occurs in vascularized tissue in response to harmful stimuli that is perceived as being a threat to tissue homeostasis. It is a complex physiological host response that is designed to neutralize and eliminate harmful agents, initiate tissue healing, and orchestrate a return to tissue homeostasis. While inflammation is designed to be an acute event that resolves following the elimination of harmful stimuli and tissue healing, there are instances where inflammation fails to resolve and instead evolves into chronic inflammation. It is now well understood that ongoing inflammation can serve as the underlying cause of many chronic inflammatory diseases, including atherosclerosis. In fact, one of the most pressing issues that is currently faced in the field of inflammation research, one that has also become the focus of numerous ongoing investigations, is how to turn this excessive, unwarranted and undesirable inflammation response off. Once thought to be a passive and simple process, resolution is now understood to be an active and complex process that is orchestrated by various inflammatory mediators, signaling pathways and biophysical processes. The discovery of novel biosynthetic pathways that turn on the pro-resolution signals has lead to a surge in research aimed at taking a closer look at processes that can stimulate the resolution of inflammation. While major advances in the field have resulted in a better understanding of the proactive nature of resolution, many of the mechanisms involved are still unknown. To date, the repertoire of chemokine receptors that participate in macrophage clearance during resolution, for the most part, remain unidentified. Overall, there is a growing appreciation that the discovery of mechanisms involved in the resolution responses can lead to the development of novel therapeutic approaches to resolve many chronic inflammatory diseases. Syndecan-1 (Sdc-1), a member of a family of cell surface proteoglycans, has been previously shown to regulate events relevant to tissue repair and chronic injury responses. Macrophage Sdc-1 expression during inflammation has been reported to be protective in various inflammatory models. Given these observations, we hypothesize that Sdc-1 expression on macrophages is a critical component of an anti-inflammatory, pro resolution program necessary for the successful resolution of inflammatory response. In this dissertation, we report the presence of a unique population of macrophages expressing Sdc-1 that are present within the vascular wall of mice undergoing atherosclerosis. Consistent with previous publications, the presence of Sdc-1 expressing macrophages was found to limit atherosclerosis progression. In addition, Sdc-1 expression on macrophages was associated with anti-inflammatory M2 polarization state and high intrinsic motility. Macrophage Sdc-1 expression was also linked with efferocytosis and enhanced macrophage egress from the site of inflammation to the draining lymphatic network. Moreover, we discovered that the chemokine receptor CXCR4, which was found on Sdc-1 expressing macrophages, was also involved in macrophage egress during inflammation resolution. In summary, while the overall mechanism regulating resolution processes is still unknown, our work has managed to identify two components that are involved in the process: macrophage Sdc-1 and CXCR4. Collectively, these results reinforce the physiological significance of macrophage efferocytosis and macrophage motility as endogenous modulators of the inflammatory response.

Although utilization of polarimetry techniques for recognition of military and civilian targets is well established in the narrowband context, it is not yet fully established in a broadband sense as compared to planetary area of research. The concept of combining polarimetry together with certain areas of broadband technology and thus forming a robust signature and feature set has been the main theme of this thesis. This is important, as basing the feature set on multiple types of signatures can increase the accuracy of the recognition process. In this thesis, the concept of radar target recognition based upon a polarization signature in a broadband context is examined. A proper UWB radar signal can excite the target dominant resonances and, consequently, reveal information about the target principle dimensions; while diversity in the polarization domain revealed information about the target shape. The target dimensions are used to classify the target, and then information about its shape is used to identify it. Fused together and inferred from the target characteristic polarization states, it was verified that the polarization information at dominant resonant frequencies have both a physical interpretation and attributes (as seen in section ‎3.4.3) related to the target symmetry, linearity, and orientation. In addition, this type of information has the ability to detect the presence of major scattering mechanisms such as strong specular reflection as in the case of the cylinder flat ends. Throughout the thesis, simulated canonical targets with similar resonant frequencies were used, and thus identification of radar targets was based solely on polarization information. In this framework, the resonant frequencies were merely identified as peaks in the frequency response for simple or low damping targets such as thin metal wires, or alternatively identified as the imaginary parts of the complex poles for complex or high damping targets with significant diameter and dielectric properties. Therefore, the main contribution of this thesis originates from the ability to integrate the optimum polarization states in a broadband context for improved target recognition performance. In this context, the spectral dispersion originating from the broad nature of the radar signal, the lack of accuracy in extracting the target resonances, the robustness of the polarization feature set, the representation of these states in time domain, and the feature set modelling with spatial variation are among the important issues addressed with several approaches presented to overcome them. The general approach considered involved a subset of “representative” times in the time domain, or correspondingly, “representative frequencies” in the frequency domain with which to associate optimum polarization states with each member of the subset are used. The first approach in chapter ‎3 involved the polarization representation by a set of frequency bands associated with the target resonant frequencies. This type of polarization description involved the formulation of a wideband scattering matrix to accommodate the broad nature of the signal presentation with appropriate bandwidth selection for each resonance; good estimation of the optimum polarization states in this procedure was achievable even for low signal-to-noise ratios. The second approach in chapter ‎4 extended the work of chapter ‎3 and involved the modification of the optimum polarization states by their associated powers. In addition, this approach included an identification algorithm based on the nearest neighbour technique. To identify the target, the identification algorithm involved the states at a set of resonant frequencies to give a majority vote. Then, a comparison of the performance of the modified polarization states and the original states demonstrated good improvement when the modified set is used. Generally, the accuracy of the resonance set estimate is more reliable in the time domain than the frequency domain, especially for resonances well localized in time. Therefore, the third approach in chapter ‎5 deals with the optimum states in the time domain where the extension to a wide band context was possible by the virtue of the polarization information embodied in the energy of the resonances. This procedure used a model-based signature to model the target impulse response as a set of resonances. The relevant resonance parameters, in this case, the resonant frequency and its associated energy, were extracted using the Matrix Pencil of Function algorithm. Again, this approach of sparse representation is necessary to find descriptors from the target impulse response that are time-invariant, and at the same time, can relate robustly to the target physical characteristics. A simple target such as a long wire showed that indeed polarization information contained in the target resonance energies could reflect the target physical attributes. In addition, for noise-corrupted signals and without any pulse averaging, the accuracy in estimating the optimum states was sufficiently good for signal to noise ratios above 20dB. Below this level, extraction of some members of the resonance set are not possible. In addition, using more complex wire models of aircraft, these time-based optimum states could distinguish between similar dimensional targets with small structural differences, e.g. different wing dihedral angles. The results also showed that the dominant resonance set has members belonging to different structural sections of the target. Therefore, incorporation of a time-based polarization set can give the full target physical characteristics. In the final procedure, a statistical Kernel function estimated the feature set derived previously in chapter ‎3, with aspect angle. After sampling the feature set over a wide set of angular aspects, a criterion based on the Bayesian error bisected the target global aspect into smaller sectors to decrease the variance of the estimate and, subsequently, decrease the probability of error. In doing so, discriminative features that have acceptable minimum probability of error were achievable. The minimum probability of error criterion and the angular bisection of the target could separate the feature set of two targets with similar resonances.

Ce mémoire présente les travaux effectués sur le développement d’un dispositif tout-optique de contrôle de l’état de polarisation de la lumière, appelé attracteur de polarisation. En effet, cette caractéristique de la lumière demeure une variable incontrôlable qui peut dégrader les performances des dispositifs tout-optiques. Basé sur l’interaction non linéaire entre deux ondes contrapropagatives au sein d’une fibre optique, ce dispositif permet de contrôler l’état de polarisation de la lumière sans pertes dépendantes de la polarisation.Il est tout d’abord effectué une étude approfondie des propriétés de l’attracteur de polarisation qui conduit au contrôle et à la stabilisation de l’état de polarisation d’un flux de données optiques aux formats NRZ et RZ cadencé à 10 Gb/s dans des fibres de plusieurs kilomètres. Par la suite, cette fonction de régénération tout-optique est associée à d’autres fonctions de régénération telles que l’amplification Raman et le régénérateur de Mamyshev dans le but de régénérer des flux de données optiques à des débits supérieurs à 10 Gb/s.Enfin, une extension de l’attracteur de polarisation, appelé Omnipolariseur, est étudiée où la lumière interagit avec elle-même grâce à un dispositif de réflexion inséré à l’autre extrémité de la fibre optique. La lumière est alors capable d’auto-organiser son état de polarisation, ce qui démontre la capacité de l’Omnipolariseur par exemple à stabiliser l’état de polarisation d’un flux de données optiques RZ à 40 Gb/s à 1550 nm / This thesis deals with the work the development of an all-optical device for the control of the polarization state of light. Actually, this feature of light remains so far an uncontrolled variable, which can degrade the performances of all-optical systems. Based on nonlinear interaction between two counterpropagating waves inside an optical fiber, this device called polarization attractor allows to control the polarization state of light without polarization dependent losses.In a first part, we carry out extensive studies of the polarization attractor properties leading to the control and the regeneration of the polarization state of the 10-Gb/s NRZ and RZ telecommunication signals. Then, this all-optical regeneration function is associated with other regeneration functions, like Raman amplification and Mamyshev regenerator, in order to regenerate optical telecommunication signals at rates exceeding 10-Gb/s.Finally, we present an extension of polarization attractor, called Omnipolarizer, where the light interacts with herself by means of a reflective element inserted at the opposite end of the optical fiber. In that case, the light is able to organize its own polarization state, demonstrating the ability of Omnipolarizer to stabilize by example the polarization state of a 40-Gb/s RZ telecommunication signal at 1550 nm

La thématique de cette thèse est l'alignement moléculaire. Celui-ci est un sujet très important qui ouvre la voie sur un contrôle beaucoup plus fin de nombreux phénomènes. Ainsi, nous avons développé une nouvelle technique de mesure de l’alignement moléculaire suivant un axe et permettant d’en conserver le signe. Celle-ci est, à l’instar des techniques de mesure de l’alignement moléculaire développées dans l’équipe, basée sur la mesure de variation d’indice de réfraction induite par l’alignement moléculaire. La technique développée ensuite permet également la mesure de l’alignement moléculaire, tout en étant aussi une application de celui-ci puisqu’il permet ici la génération de troisième harmonique. L’alignement moléculaire est également mis en oeuvre dans la dernière étude puisque nous montrons qu’il apporte la résolution nécessaire à l’étude de la thermalisation d’un échantillon moléculaire excité / The thematic of this thesis is molecular alignment. The latter is a very important topic that opens the way toward a much more thin control of many phenomenons. So, we have developed a new measurement technique of the molecular alignment along one axis that permits to preserve the sign of alignment. This one is, like other measurement techniques developed by the team,based on the measurement of the refractive index variation induced by the molecular alignment.The technique developed then also permits the molecular alignment measurement, being also an application of it because it allows the third harmonic generation. In the last study, molecular alignment is implemented to show that it brings the necessary resolution for the study of an excited molecular sample thermalization

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