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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.
11

Digital holography and optical contouring

Li, Yan January 2009 (has links)
Digital holography is a technique for the recording of holograms via CCD/CMOS devices and enables their subsequent numerical reconstruction within computers, thus avoiding the photographic processes that are used in optical holography. This thesis investigates the various techniques which have been developed for digital holography. It develops and successfully demonstrates a number of refinements and additions in order to enhance the performance of the method and extend its applicability. The thesis contributes to both the experimental and numerical analysis aspects of digital holography. Regarding experimental work: the thesis includes a comprehensive review and critique of the experimental arrangements used by other workers and actually implements and investigates a number of these in order to compare performance. Enhancements to these existing methods are proposed, and new methods developed, aimed at addressing some of the perceived short-comings of the method. Regarding the experimental aspects, the thesis specifically develops:• Super-resolution methods, introduced in order to restore the spatial frequencies that are lost or degraded during the hologram recording process, a problem which is caused by the limited resolution of CCD/CMOS devices.• Arrangements for combating problems in digital holography such as: dominance of the zero order term, the twin image problem and excessive speckle noise.• Fibre-based systems linked to tunable lasers, including a comprehensive analysis of the effects of: signal attenuation, noise and laser instability within such systems.• Two-source arrangements for contouring, including investigating the limitations on achievable accuracy with such systems. Regarding the numerical processing, the thesis focuses on three main areas. Firstly, the numerical calculation of the Fresnel-Kirchhoff integral, which is of vital importance in performing the numerical reconstruction of digital holograms. The Fresnel approximation and the convolution approach are the two most common methods used to perform numerical reconstruction. The results produced by these two methods for both simulated holograms and real holograms, created using our experimental systems, are presented and discussed. Secondly, the problems of the zero order term, twin image and speckle noise are tackled from a numerical processing point of view, complementing the experimental attack on these problems. A digital filtering method is proposed for use with reflective macroscopic objects, in order to suppress both the zero-order term and the twin image. Thirdly, for the two-source contouring technique, the following issues have been discussed and thoroughly analysed: the effects of the linear factor, the use of noise reduction filters, different phase unwrapping algorithms, the application of the super-resolution method, and errors in the illumination angle. Practical 3D measurement of a real object, of known geometry, is used as a benchmark for the accuracy improvements achievable via the use of these digital signal processing techniques within the numerical reconstruction stage. The thesis closes by seeking to draw practical conclusions from both the experimental and numerical aspects of the investigation, which it is hoped will be of value to those aiming to use digital holography as a metrology tool.
12

La libération modifiée de principes actifs, développement de deux approches / The modified drug release, development of two approaches

Dekyndt, Bérangère 19 January 2015 (has links)
Les thérapeutiques individualisées et ciblées se développent actuellement, les formes galéniques évoluent donc en parallèle pour contrôler la libération des principes actifs (PA) et les conduire au plus proche des sites d’intérêts. Les formes orales solides représentent les formulations galéniques les plus utilisées, faciles d’emploi, indolores et réduisant le risque d’infection. Lors de leur conception, il est aussi possible de moduler la libération du PA.Deux approches sont étudiées dans ce manuscrit, l’une correspond au ciblage de la libération d’un PA vers son site d’action thérapeutique qui est le colon, la seconde consiste à contrôler la libération du PA pour maintenir une concentration constante, minimiser les effets indésirables et les périodes de présence de concentrations sub-thérapeutiques au niveau du site d’action.Première approche :Les traitements des Maladies Inflammatoires Chroniques de l’Intestin (MICI) peuvent être significativement améliorées par une libération localisée du PA. Une des approches est l’utilisation d’enrobages composés de polysaccharides dégradés par les enzymes sécrétées par la microflore colique. Mais l’absence d’une méthode in vitro reproductible simulant les conditions physiologiques du colon et l’impact potentiel des traitements antibiotiques associées qui pourraient affecter la quantité et la qualité des bactéries présentes et des enzymes sécrétées est un obstacle à sa mise au point. L’objectif de l’étude était d’effectuer un screening de polysaccharides ayant un intérêt dans le développement de nouvelles formulations à libération colique. Après cette sélection, la libération des formulations retenues ont été évaluées par une méthode utilisant des selles de patients atteints de MICI traités ou non par antibiothérapie. Enfin, l’utilisation de mélanges bactériens pour un éventuel remplacement de l’utilisation de selles fraiches a été évaluée.Seconde approche : Les formes orales enrobées présentent un grand potentiel pour la libération contrôlée de PA. Néanmoins, il est difficile d’obtenir une libération à vitesse constante avec ce type de formulation. Ceci est généralement dû au rôle prédominant du transport de masse par diffusion, ce qui entraine, avec le temps, une diminution de la concentration en PA au cœur du système, donc une réduction du gradient de concentration qui est la force motrice de la libération du PA. Ce type de cinétique de libération peut être inapproprié pour un traitement médicamenteux sûr et efficace. Malgré l’importance pratique de ce défi crucial de formulation, étonnamment, peu de stratégies efficaces sont connues. Dans cette étude, une nouvelle approche, basée sur une succession de couches de PA et de polymères (initialement dépourvu de PA) présentant une distribution initiale de PA non homogène, associé à un effet de temps de latence et à une diffusion partielle initiale à travers le noyau de la minigranule. Des variations de type, de quantité, d’épaisseur et de séquence des couches de PA et de polymères ont été testées. Un système assez simple composé de quatre couches (deux couches de PA et deux couches de polymère) permettait d’aboutir à une libération relativement constante durant 8h. / Individualized and targeted therapies are currently developed, therefore the dosage forms move in parallel to control the drug release and drive it nearest to interest sites. Solid oral dosage forms are the pharmaceutical formulations the most common, easy to use, painless and reducing the infectious risk. In these formulation designs, it is also possible to adjust the drug release.Two approaches are discussed in this manuscript, the first one targets the drug release to the therapeutic site of action which is the colon, and the second one consists on controlling the drug release to maintain a constant concentration, minimize side effects and periods of presence of sub-therapeutic concentrations at the site of action.The first approach:The treatment of colonic disease like Inflammatory Bowel Diseases (IBD), can be significantly improved via local drug delivery. One approach is to use polysaccharide coatings, which are degraded by enzymes secreted by the colonic microflora. However, the lack of a reliable in vitro test simulating conditions in a living colon and the potential impact of associated antibiotic treatments that could affect the quality and quantity of bacteria and enzymes secreted is an obstacle to its development. The aim of the study was to perform a screening of polysaccharides suitable for the development of new colonic release formulations. After this selection, the drug release of selected formulations were evaluated by a method using the stools of IBD patients treated or not with antibiotics. Finally, the use of bacterial mixtures substituting fresh fecal samples has been evaluated.The second approach: Coated pellets offer a great potential for controlling drug delivery systems. However, constant drug release rates are difficult to achieve with this type of dosage forms if the drug is freely water-soluble. This is because diffusional mass transport generally plays a major role and with time the drug concentration within the system decreases, resulting in decreased concentration gradients, which are the driving forces for drug release. This type of release kinetics might be inappropriate for an efficient and safe drug treatment. Despite the great practical importance of this potentially crucial formulation challenge, surprisingly little is yet known about efficient formulations. In this study, a novel approach is presented based on sequential layers of drug and polymer (initially free of drug) to provide a non-homogeneous initial drug distribution, combined with lag-time effects and partial initial drug diffusion towards the pellet’s core. By changing the type, number, thickness and sequence of the drug and polymer layers, a rather simple 4 layers system (2 drug and 2 polymer layers) allowed an about constant drug release during 8 h.
13

Development of a novel gastro-retentive delivery system using alfuzosin HCl as a model drug

Liu, Quan. January 2010 (has links)
The objectives of this project encompass the design and development of a drug delivery system to continuously deliver therapeutic agents from the stomach to the proximal region of the intestine. The delivery system designed would have sufficient gastric residence time together with near zero-order release kinetics. The physicochemical properties pertaining to the formulation development of the model drug (alfuzosin HCl) were evaluated. Excipients were selected based on the studies of their physicochemical properties and compatibility with the active ingredient. Gastro-retentive dosage forms have been the topic of interest in recent years as a practical approach in drug deliveries to the upper GI tract or for release prolongation and absorption. These dosage forms are particularly suitable for drugs that have local effects on the gastric mucosa in the stomach. Other candidates include drugs that are likely to be absorbed in the upper small intestine, or drugs that are unstable in basic environment of distal intestine and colon or those with low solubility at elevated pH conditions (i.e. weak bases). To develop a gastro-retentive delivery system the following steps were taken. First, to investigate the possible incompatibility issues between the model drug and excipients to be used for the delivery system. Stability and physicochemical properties of the active agent and its mixture with excipients were studied using analytical techniques such as Raman spectroscopy and Differential scanning calorimetry (DSC). No incompatibility issues were detected. Second, Kollidon SR as a relatively new release-rate controlling polymer was incorporated in the final formulation. For solid dosage form the ability of the final powder mix to flow well during manufacturing and the intrinsic characteristics that make it compressible are critical. The in-depth compaction study of Kollidon SR was assessed with the help of a compaction simulator. The flowability, swelling and erosion behavior together with release-rate retarding properties of Kollidon SR were also assessed. The final oral delivery system was based on Kollidon SR and Polyethylene Oxide (PEO) 303 as a monolithic matrix system. The noneffervescent monolithic matrix was made by direct compression. In vitro evaluation of the designed system released the active content in a near zero manner. The dosage form was bouyant in pH 2.0 acidic buffer with no floatation lag time which minimizes the possibility of early gastric emptying. / Pharmaceutics
14

Formulation and Fabrication of a Novel Subcutaneous Implant for the Zero-Order Release of Selected Protein and Small Molecule Drugs

Zhi, Kaining January 2017 (has links)
Diabetes is a leading cause of death and disability in the United States. Diabetes requires a lifetime medical treatment. Some diabetes drugs could be taken orally, while others require daily injection or inhalation to maximize bioavailability and minimize toxicity. Parenteral delivery is a group of delivery routes which bypass human gastrointestinal track. Among all the parenteral methods, we chose subcutaneous implant based on its fast act and high patient compliance. When using subcutaneous implant, drug release needs to be strictly controlled. There are three major groups of controlled release methods. Solvent controlled system is already used as osmotic implant. Matrix controlled system is used in Zoladex® implant to treat cancer. Membrane controlled systems is widely used in coating tablets, but not that popular as an implant. Based on the research reported by previous scientists, we decided to build a hybrid system using both matrix and membrane control to delivery human insulin and other small molecule drugs. Subcutaneous environment is different from human GI track. It has less tolerance for external materials so many polymers cannot be used. From the FDA safe excipient database, we selected albumin as our primary polymer and gelatin as secondary choice. In our preliminary insulin diffusion study, we successfully found that insulin mixed with albumin provided a slower diffusion rate compared with control. In addition, we added zinc chloride, a metal salt that can precipitate albumin. The insulin diffusion rate is further reduced. The preliminary study proved that matrix control using albumin is definitely feasible and we might add zinc chloride as another factor. In order to fabricate an implant with appropriate size, we use lyophilisation technology to produce uniformly mixed matrix. Apart from albumin and human insulin, we added sucrose as protectant and plasticizer. The fine powder after freeze-dry was pressed as a form of tablet. The tablets were sealed in Falcon® cell culture insert. Cell culture insert provide a cylinder shape and 0.3 cm2 surface area for drug release. Insulin release study provided a zero order kinetics from prototypes with zinc chloride or 0.4 micron pore size membrane. Caffeine was used as a model drug to investigate the releasing mechanism. Three pore size membranes (0.4, 3 and 8 micron) were tested with same formulation. While 0.4 micron prototypes provided the slowest release, 3 micron ones surprisingly released caffeine faster than 8 micron implants. We calculated the porosity with pore size and concluded that the percentage of open area on a membrane is the key point to control caffeine release. 0.4 micron membranes were used for future research. We increased the percentage of albumin in our excipient, and achieved a slower caffeine release. However, the zero order release could only last for 3 days. After we replaced sucrose with gelatin, a 5 day zero order release of caffeine was achieved. With all the results, we proposed our “Three Phase” drug release mechanism controlled by both membrane and matrix. Seven other small molecule drugs were tested using our prototype. Cloudy suspension was observed with slightly soluble drugs. We updated our “Three Phase” drug release mechanism with the influence of drug solubility. Data shows that releasing rate with same formulation and membrane follows the solubility in pH 7.4. This result proves that our prototype might be used for different drugs based on their solubility. Finally, with all the information of our prototype, we decided to build a “smart insulin implant” with dose adjustment. We proposed an electrical controlled implant with different porosity membranes. Solenoid was used as the mechanical arm to control membrane porosity. 3-D printing technology was used to produce the first real prototype of our implant. Finally, insulin implant with clinically effective insulin release rate was achieved. / Pharmaceutical Sciences
15

INJECTABLE DELIVERY SYSTEM BASED ON 5-ETHYLENE KETAL-ε -CAPROLACTONE FOR THE DELIVERY OF VEGF AND HGF FOR TREATING CRITICAL LIMB ISCHEMIA

Babasola, IYABO 23 May 2012 (has links)
The aim of this thesis is to determine the feasibility of an injectable delivery system based on 5-ethylene ketal ε-caprolactone for localized delivery of vascular endothelial growth factor (VEGF) and hepatocyte growth factor (HGF) for treating critical limb ischemia. HGF and VEGF were chosen because of their ability to simultaneously stimulate the proliferation and migration of endothelial cells, to initiate the formation of blood vessels and the recruitment of pericytes to stabilize the blood vessels. Homopolymer of 5-ethylene ketal ε-caprolactone and its copolymer with D,L-Lactide were synthesized by ring opening polymerization using hydrophobic initiator (octan-1-ol) or an hydrophilic initiator (MPEG), and stannous octanoate as a co-initiator/catalyst. The resulting polymers were amorphous and viscous liquids at room temperature. The viscosity, biodegradation rate, and release rate were varied by copolymerizing with D,L-lactide and/or initiating with MPEG or octan-1-ol. In vitro, the polymers degraded with surface erosion characterized by a nearly linear mass loss with time with no significant change in number average molecular weight and glass transition temperature. The ratio of EKC to DLLA in the copolymer remained the same throughout the degradation studies. A similar degradation mechanism was observed in vivo when the copolymer initiated with octan-1-ol was implanted subcutaneously in rats. In vivo, the polymer exhibited a moderate chronic inflammatory response, characterized by the presence of neutrophils, macrophages, fibroblasts and fibrous capsule formation. The inflammatory response decreased with time but was still on going after 18 weeks of subcutaneous implantation. Protein release from the polymer was transported by convection through the hydrated polymer region, at a rate determined by the osmotic pressure generated and the hydraulic conductivity of the polymer. Highly bioactive VEGF and HGF were released in a sustained manner, without burst effect for over 41 days when delivered simultaneously, using the osmotic release mechanism. VEGF was released at the rate of 36 ± 7 ng/day for 41 days, while HGF was released at the rate of 16 ± 2 ng/day for 70 days. Factors that influenced release of proteins were their solubility in the concentrated trehalose solution and hydraulic permeability of the polymer. This delivery system can serve as a potential vehicle for controlled release of VEGF and HGF for treating critical limb ischemia or the controlled release of other proteins for other clinical applications. / Thesis (Ph.D, Chemical Engineering) -- Queen's University, 2012-05-23 10:18:48.307
16

Anomalous nature of metamaterial inclusion and compact metamaterial-inspired antennas model for wireless communication systems : a study of anomalous comportment of small metamaterial inclusions and their effects when placed in the vicinity of antennas, and investigation of different aspects of metamaterial-inspired small antenna models

Jan, Naeem A. January 2017 (has links)
Metamaterials are humanly engineered artificial electromagnetic materials which produce electromagnetic properties that are unusual, yet can be observed readily in nature. These unconventional properties are not a result of the material composition but rather of the structure formed. The objective of this thesis is to investigate and design smaller and wideband metamaterial-inspired antennas for personal communication applications, especially for WiMAX, lower band and higher band WLAN applications. These antennas have been simulated using HFSS Structure Simulator and CST Microwave Studio software. The first design to be analysed is a low-profile metamaterial-inspired CPW-Fed monopole antenna for WLAN applications. The antenna is based on a simple strip loaded with a rectangular patch incorporating a zigzag E-shape metamaterial-inspired unit cell to enable miniaturization effect. Secondly, a physically compact, CSRR loaded monopole antenna with DGS has been proposed for WiMAX/WLAN operations. The introduction of CSRR induces frequency at lower WLAN 2.45 GHz band while the DGS has provided bandwidth enhancement in WiMAX and upper WLAN frequency bands, keeping the radiation pattern stable. The next class of antenna is a compact cloud-shaped monopole antenna consisting of a staircase-shaped DGS has been proposed for UWB operation ranges from 3.1 GHz to 10.6 GHz. The novel shaped antenna along with carefully designed DGS has resulted in a positive gain throughout the operational bandwidth. Finally, a quad-band, CPW-Fed metamaterial-inspired antenna with CRLH-TL and EBG is designed for multi-band: Satellite, LTE, WiMAX and WLAN.
17

Anomalous Nature Of Metamaterial Inclusion and Compact Metamaterial-Inspired Antennas Model For Wireless Communication Systems. A Study of Anomalous Comportment of Small Metamaterial Inclusions and their Effects when Placed in the Vicinity of Antennas, and Investigation of Different Aspects of Metamaterial-Inspired Small Antenna Models

Jan, Naeem A. January 2017 (has links)
Metamaterials are humanly engineered artificial electromagnetic materials which produce electromagnetic properties that are unusual, yet can be observed readily in nature. These unconventional properties are not a result of the material composition but rather of the structure formed. The objective of this thesis is to investigate and design smaller and wideband metamaterial-inspired antennas for personal communication applications, especially for WiMAX, lower band and higher band WLAN applications. These antennas have been simulated using HFSS Structure Simulator and CST Microwave Studio software. The first design to be analysed is a low-profile metamaterial-inspired CPW-Fed monopole antenna for WLAN applications. The antenna is based on a simple strip loaded with a rectangular patch incorporating a zigzag E-shape metamaterial-inspired unit cell to enable miniaturization effect. Secondly, a physically compact, CSRR loaded monopole antenna with DGS has been proposed for WiMAX/WLAN operations. The introduction of CSRR induces frequency at lower WLAN 2.45 GHz band while the DGS has provided bandwidth enhancement in WiMAX and upper WLAN frequency bands, keeping the radiation pattern stable. The next class of antenna is a compact cloud-shaped monopole antenna consisting of a staircase-shaped DGS has been proposed for UWB operation ranges from 3.1 GHz to 10.6 GHz. The novel shaped antenna along with carefully designed DGS has resulted in a positive gain throughout the operational bandwidth. Finally, a quad-band, CPW-Fed metamaterial-inspired antenna with CRLH-TL and EBG is designed for multi-band: Satellite, LTE, WiMAX and WLAN.
18

Bimodal Amphiphilic Polymer Conetworks: Structure-Property Characterization, Processing and Applications

Guzman Cardozo, Gustavo A., Guzman January 2016 (has links)
No description available.
19

Caractérisation pharmacocinétique et pharmacodynamique de la lidocaïne avec ou sans adrénaline lors d’un bloc paravertébral du plexus brachial chez le chien

Choquette, Amélie 04 1900 (has links)
Au cours des vingt dernières années, l’anesthésie régionale est devenue, autant en médecine vétérinaire qu’humaine, un outil essentiel à l’élaboration de protocoles analgésiques péri-opératoires. Parmi l’éventail de techniques mises au point en anesthésie canine, le bloc paravertébral du plexus vertébral (PBPB) et sa version modifiée sont d’un grand intérêt pour toute procédure du membre thoracique, dans sa portion proximale. Toutefois, l’essentiel des données publiées à ce jour provient d’études colorimétriques, sans évaluation clinique, et peu d’information est disponible sur les techniques de localisation nerveuse envisageables à ce site. Notre étude visait à décrire une approche échoguidée du PBPB modifié, puis à caractériser ses paramètres pharmacocinétiques et pharmacodynamiques après administration de lidocaïne (LI) ou lidocaïne adrénalinée (LA). Huit chiens ont été inclus dans un protocole prospectif, randomisé, en aveugle et croisé, réparti sur trois périodes. L’impact pharmacodynamique du bloc effectué avec LI ou LA a été évalué régulièrement pour 180 min suivant son exécution. Le traitement à l’adrénaline n’a pas démontré d’impact significatif (P = 0,845) sur la durée du bloc sensitif, tel qu’évalué par un stimulus douloureux mécanique appliqué aux dermatomes ciblés. À l’opposé, l’atteinte proprioceptive évaluée par la démarche a été trouvée prolongée (P = 0,027) et le bloc moteur mesuré par le pic de force verticale (PVF) au trot sur la plaque de force s’est avéré plus marqué (PVF réduit; P = 0,007) sous LA. À l’arrêt comme au trot, le nadir de la courbe PVF-temps a été trouvé retardé (P < 0,005) et la pente ascendante de retour aux valeurs normales adoucie (P = 0,005). Parallèlement aux évaluations cliniques, des échantillons plasmatiques ont été collectés régulièrement afin de quantifier et décrire le devenir pharmacocinétique de la lidocaïne. Parmi les trois élaborés, un modèle bi-compartimental doté d’une double absorption asynchrone d’ordre zéro a finalement été sélectionné et appliqué aux données expérimentales. Sous LA, la Cmax a été trouvée significativement diminuée (P < 0,001), les phases d’absorption prolongées [P < 0,020 (Dur1) et P < 0,001 (Dur2)] et leurs constantes réduites [P = 0,046(k01) et P < 0,001 (k02)], le tout en concordance avec les effets proprioceptifs et moteurs rapportés. Bien que l’extrapolation du dosage soit maintenant théoriquement envisageable à partir du modèle mis en lumière ici, des études supplémentaires sont encore nécessaires afin d’établir un protocole de PBPB d’intérêt clinique. L’analyse sur plaque de force pourrait alors devenir un outil de choix pour évaluer l’efficacité du bloc dans un cadre expérimental. / Over the last decade, regional anaesthesia has become a gold standard for peri-surgical management in veterinary medicine. Among the many techniques developed for analgesia in dogs, the paravertebral brachial plexus block (PBPB) is of great interest when targeting the proximal half of the thoracic limb. Yet, most available data on this technique is based on colorimetric protocols rather than clinical evaluation, and there are very few published results for PBPB execution using nerve location techniques. Through this work, we wished to describe an ultrasound-guided approach of the PBPB and characterize its pharmacokinetic/ pharmacodynamic parameters when executed with either lidocaine alone (LI) or combined to adrenaline (LA). Eight dogs were included in a prospective, randomised, blinded, crossover protocol performed over three distinct periods. Pharmacodynamic impact of LI and LA was compared for 180 minutes after block administration. No significant difference (P = 0.845) was noted between treatments regarding length of the sensitive block, as evaluated regularly through a mechanical painful stimulus applied to selected dermatomes. On the opposite, gait examination showed a longer proprioceptive deficit using LA (P = 0.027). Motor block measured with dynamic force plate analysis showed a lower peak vertical force with LA than LI (P = 0.007). For both dynamic and static evaluations, nadir was clearly delayed (P < 0.005) and the ascending slope back to baseline significantly softened (P = 0.005) in the LA group. Throughout block execution and evaluation, blood samples were collected regularly in order to quantify and describe lidocaine kinetics. Models where developed and compared. A two-compartment model with dual zero-order absorption processes was selected as the best fit for our experimental data. Cmax proved to be significantly reduced with LA (P < 0.001), thus reducing potential toxicity. Absorption phase was prolonged [P < 0.020 (Dur1) and P < 0.001 (Dur2)] and zero-order absorption constant rates lowered [P = 0.046(k01) and P < 0.001 (k02)] following adrenaline addition, in accordance with the previously noted prolonged gait and motor effects. Though dosage extrapolation is now possible using the model developed and tested here, further studies would be needed to establish a PBPB protocol of more clinical interest. Then, force plate analysis could become a key tool for block quality assessment, as both dynamic and static measurements proved to be the reliable ways to collect ground reaction force (GRF) data.
20

Méthodes optiques innovantes pour le contrôle rapide et tridimensionnel de l’activité neuronale / Advanced optical methods for fast and three-dimensional control of neural activity

Hernández Cubero, Óscar Rubén 22 January 2016 (has links)
La révolution en cours des outils optogénétiques - des protéines photosensibles génétiquement induites qui peuvent activer, inhiber et enregistrer l'activité neuronale - a permis d'ouvrir une nouvelle voie pour relier l'activité neuronale et la cognition. Néanmoins, pour profiter au mieux de ces outils nous avons besoin de méthodes optiques qui peuvent projeter des schémas d'illumination complexes dans le cerveau. Pendant mon doctorat, j'ai travaillé sur deux nouveaux systèmes complémentaires pour la stimulation de l'activité neuronale. Le premier système combine des déflecteurs acousto-optiques et une illumination Gaussienne à faible ouverture numérique pour produire une photo activation rapide des outils optogénétiques. La capacité d'accès aléatoire du système permet de délivrer des séquences d'illumination spatialement et temporellement complexes qui simulent avec succès les schémas physiologiques de l'activité des fibres moussues dans des tranches de cerveaux. Ces résultats démontrent que les schémas de stimulation optogénétique peuvent être utilisés pour recréer l'activité en cours et étudier les microcircuits du cerveau dans un environnement physiologique. Alternativement, l'holographie générée par ordinateur (HGO) permet d'améliorer grandement les stimulations optogénétiques en répartissant efficacement la lumière sur plusieurs cibles cellulaires simultanément. Néanmoins, le confinement axial se dégrade pour des schémas d'illuminations larges. Afin de d'améliorer ce point, l’HGO peut être combinée avec une technique de focalisation temporelle qui confine axialement la fluorescence sans dépendre de l'allongement latéral. Les précédentes configurations maintiennent l'excitation non linéaire à un unique plan focal spatiotemporel. Dans cette thèse, je décris deux méthodes différentes qui permettent de dépasser ces limitations et de permettre la génération de schémas focalisés tridimensionnellement, à la fois spatialement et temporellement. / The ongoing revolution of optogenetic tools – genetically encoded light-sensitive proteins that can activate, silence and monitor neural activity – has opened a new pathway to bridge the gap between neuronal activity and cognition. However, to take full advantage of these tools we need optical methods that can deliver complex light patterns in the brain. During my doctorate, I worked on two novel and complementary optical systems for complex spatiotemporally neural activity stimulation. The first system combined acousto-optic deflectors and low numerical aperture Gaussian beam illumination for fast photoactivation of optogenetic tools. The random-access capabilities of the system allowed to deliver complex spatiotemporal illumination sequences that successfully emulated physiological patterns of cerebellar mossy fiber activity in acute slices. These results demonstrate that patterned optogenetic stimulation can be used to recreate ongoing activity and study brain microcircuits in a physiological activity context. Alternatively, Computer Generated Holography (CGH) can powerfully enhance optogenetic stimulation by efficiently shaping light onto multiple cellular targets simultaneously. Nonetheless, the axial confinement degrades for laterally extended illumination patterns. To address this issue, CGH can be combined with temporal focusing that axially confines fluorescence regardless of lateral extent. However, previous configurations restricted nonlinear excitation to a single spatiotemporal focal plane. In this thesis, I describe two alternative methods to overcome this limitation and enable three-dimensional spatiotemporal focused pattern generation.

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