Дисертації з теми "Lumière adaptative"
Оформте джерело за APA, MLA, Chicago, Harvard та іншими стилями
Ознайомтеся з топ-27 дисертацій для дослідження на тему "Lumière adaptative".
Біля кожної праці в переліку літератури доступна кнопка «Додати до бібліографії». Скористайтеся нею – і ми автоматично оформимо бібліографічне посилання на обрану працю в потрібному вам стилі цитування: APA, MLA, «Гарвард», «Чикаго», «Ванкувер» тощо.
Також ви можете завантажити повний текст наукової публікації у форматі «.pdf» та прочитати онлайн анотацію до роботи, якщо відповідні параметри наявні в метаданих.
Переглядайте дисертації для різних дисциплін та оформлюйте правильно вашу бібліографію.
Gemayel, Pierre. "Optique adaptative par modulateur spatial de lumière en microscopie et holographie." Thesis, Mulhouse, 2016. http://www.theses.fr/2016MULH9294/document.
Since the 50s, recovering the phase information of a diffracted beam has a major interest in several fields such as microscopy, astronomy and many others. Generally, the solutions fall into two broad categories: interferometric methods and iterative methods based on beam propagation. The advantage of the latter is that they are less sensitive to noise, and their experimental implementation is simpler. Also, the progress in computer technologies as well in digital imaging devices makes the application of this approach easier and more interesting. However, even if the effectiveness of these methods has been demonstrated in several fields, their use remained limited because of certain requirements on the experimental conditions and the non-convergence of their algorithm to a single solution in many cases. This is even more true for the so-called "complex objects", having an amplitude and a phase, which can greatly reduce their field of application. To overcome the convergence problems and improve the robustness of these methods, many experimental strategies have been employed. They are all based on the same principle, which consists of introducing new well-known constraints in the object plane. This increases the number of acquired spectrum, and therefore diversifies the sources of information about the starting object, which will help the iterative algorithm to converge more quickly towards the final solution. As examples of such experimental strategies, one can record several spectra from different areas of the object, or modulate the wavelength of the incident beam, or also acquire the spectrums across two or more parallel planes connected through Fresnel or Fourier transform.In this context, the present work aims to experimentally demonstrate a technique known as SSPR (Spread Spectrum Phase Retrieval), proposed in 2007 by Zhang, while modifying it in order to make it more flexible. The idea is to introduce, using a liquid crystal spatial light modulator M strong phase modulation into the object field, then record in the Fourier plane the M corresponding spectrums. These M acquisitions will then be used in an iterative algorithm what will allow us to recover the object wavefront by simulating the propagation of the light between spatial and frequency spaces. The first part of this thesis includes a complete study on spatial light modulators; in order to select which one will be best suited for our application. Once liquid crystal spatial light modulators are selected, we present their technical characteristics, as well as the calibration tests needed to ensure their linear and optimal functioning. Then we show several possible applications with this type of component, in various scientific fields, like holography, microscopy, adaptive optics and interferometric methods to reconstruct the phase of a beam.In the second part, we focus our work around the SSPR iterative method. We will show how to make the application of this method simpler by using a liquid crystal spatial light modulator, and by working in Fourier plane instead of Fresnel plane. However, after applying SSPR we have noticed that the quality of experimental results is very inferior to the quality of simulation results. Therefore, a detailed study of the noise sources is conducted. Each of these noise sources adds its own contribution, yet modulator cross-talk remains the factor that deteriorates the most the quality of reconstruction. In fact liquid crystal spatial light modulators are known to have a strong cross-talk between their pixels commonly recognized as fringing field effect. As the pixels are micrometric, each addressed one affects its neighbors, and thus, the phase retardation obtained from a pixel will not be uniform over its entire surface. This will result in a blurring effect of the desired sharp edge between the pixels; therefore, the real displayed phase map will be very different from the addressed one. [...]
Abelard, Clément. "Micro modulateur spatial de lumière transmissif pour modulation de phase et d’amplitude." Thesis, Université Grenoble Alpes (ComUE), 2018. http://www.theses.fr/2018GREAT092/document.
LETI possesses an expertise allowing to realize Spatial Light Modulators (SLMs) made in microelectronic technology on silicon, having very high resolutions and very small pixel steps. LETI wishes to use a specific LCD technology (IPS technology), on the one hand the electro-optical performances in the field of micro-display had to be investigated but on the other hand allows to keep costs down and reduce the number of manufacturing steps. The objective of this thesis is to evaluate on the basis of simulations and technical achievements, the performance of a micro-SLM IPS used in phase modulation and amplitude.Our investigations have been carried out on four major areas of study. The first axis is the search and testing of a specific software (LCDMaster) to simulate liquid crystal cells and floating electrodes. The second axis according to different designs of pixel and the different liquid crystal alignment modes (Homogeneous, vertical and twisted) with an IPS type control, to investigate the performances in modulation phase. The best results were obtained for a vertical alignment providing a phase shift of 2π. In addition, the performance of an adaptive optics device integrating the studied SLM has been investigated. The third axis of study focused on the performance investigation of a liquid crystal SLM with an IPS-type control using a homogeneous alignment in amplitude modulation (static and dynamic study). This study also makes it possible to study the possibilities of reducing the response time of the cell. It resulted in two SLM designs. The first design with two levels of electrodes separated by an insulator to reproduce a Faraday type effect. The second has drastically reduced the response time. The fourth area of research consists in testing prototypes based on these two designs to validate the performances obtained in simulation. Concordant results have been obtained and new types of IPS-controlled SLMs with state-of-the-art refreshing times have thus been designated and characterized
Peigné, Arnaud. "Holographie adaptative pour la réalisation de capteurs à fibres optiques de très grande sensibilité : application à la détection d’ondes acoustiques sous-marines." Thesis, Nice, 2016. http://www.theses.fr/2016NICE4005/document.
Fiber optic sensors are a key technology for future developments with a large field of applications ranging from structure health monitoring to medical applications. Due to its high compactness, its electromagnetic immunity and the low transmission losses in the telecom window, optical fibers are very promising for underwater acoustic waves detection. We present a method relying on adaptive holographic interferometry based on two beam coupling in an optically addressed spatial light modulator (OASLM). This method allows filtering the slow phase perturbations coming from the environment directly on the sensing optical fiber. In this work, we will first introduce the OASLM operating at 1,55 μm that we have manufactured and the realization of an adaptive holographic interferometer based on this component. Moreover, we will show that it is possible to associate this demodulation method with a multimode optical fiber to reach a better sensitivity. Finally, we will focus on sensors architectures to evaluate the benefit of this technology compared to conventional techniques
Jorand, Raphaël. "Amélioration des voies de détection et d'illumination d'un microscope SPIM pour l'imagerie 3D des sphéroïdes." Toulouse 3, 2013. http://thesesups.ups-tlse.fr/2267/.
The aim of our thesis work was to improve spheroid imaging quality focusing on the study and development of both illumination and detection path of the SPIM. This work shows the possibility to improve deep image quality by using an adaptive optics loop consisting of a deformable mirror and a Shack Hartmann wavefront sensor. In order to work, the loop needs fluorescent source points known as "guide stars", which was also a part of our study. Furthermore, we have also compared different light sheet illumination modalities (1 photon versus 2 photons, Gaussian beam or Bessel beam. . . ) as well as developing an automated and standardized image analysis procedure
Morgado, Brajones Javier. "OPTO-MECA-SPIM : imagerie dynamique et interactive de phénomènes mécanobiologiques dans les tissus." Thesis, Toulouse 3, 2019. http://www.theses.fr/2019TOU30252.
In recent years, tissue mimics (TMs) such as microtissues, spheroids, and organoid cultures have become increasingly important in life-science research, as they provide a physiologically relevant environment for cell growth, tissue morphogenesis, and stem cell differentiation. Selective Plane Illumination Microscopy (SPIM) is one of the most prominent microscopy modalities for three-dimensional tissue imaging, and a sine qua non tool to understand cell biology in TMs. However, while SPIM is regarded as a very powerful tool for TM imaging, optical microscopy suffers from certain limitations when imaging 3D samples. Indeed, scattering, absorption and optical aberrations limit the depth at which useful imaging can be done, typically no more than 100 µm. Adaptive Optics (AO) is a technique capable of improving image quality at depth by correcting the optical aberrations introduced by the sample which is seeing increasing use in fluorescence microscopes. For this thesis, I have incorporated a wavefront sensor AO scheme to SPIM, able to correct aberrations in optically thick TMs such as multi-cellular tumor spheroids (MCTS). Due to the low amount of light produced by non-linear guide stars such as the one used in our system, a custom high-sensitivity Shack-Hartmann wavefront sensor (SHWFS) was developed for our needs. In this work, I characterize the performance of this SHWFS and the ability of our system to correct aberration in various conditions, including inside TMs. I show unprecedented image quality improvements for in-depth imaging of MCTS, in regard of high-frequency detail and resolution. This allowed us to identify biologically relevant features at depths inaccessible to conventional SPIM. Up-converting nanoparticles (UCNP) are rare-earth based particles that are able to undergo photon up-conversion when illuminated, emitting light of a shorter wavelength than that of the illumination. Guide stars made from UCNP are especially attractive due to the possibility of them being excited in the near-infrared while emitting visible light, reducing photodamage produced by the illumination light. The viability of using UCNP as guide stars in biological samples in explored in this thesis
Sisaykeo, Phimpha. "Coopération internationale et protection du patrimoine au Laos : analyse du programme UNESCO-Chinon-Luang Prabang à la lumière des Policy transfer studies." Thesis, Lyon 2, 2015. http://www.theses.fr/2015LYO20155.
The development cooperation brings into play powerful forces of change and resistance at the interface of different culturally, economically, politically and institutionally systems of actors. Requests for assistance are emitted and services offerings are proposed on problems for which must be built answers adapted to situations for which they are requested. How are these answers built ? How are taken into account specificities of the actors ? How are integrated the partners cultural, economic, political and institutional characteristics in situation of significant otherness ? Finally, how is a solution of development in cooperation worked out ? This research proposes replies starting from the cooperation to heritage protection between Luang Prabang, Chinon and UNESCO from 1995 to 2015, and the mobilization of a protocol of research whose principal tools are borrowed from the analyses in terms of transfer studies
Ansarnia, Masoomeh. "Development and Test of Computer Vision and Deep Learning Methods for Dynamic Management of Urban Lighting." Electronic Thesis or Diss., Université de Lorraine, 2023. http://www.theses.fr/2023LORR0272.
This doctoral thesis has been conducted within the framework of a research contract between the French urban lighting design and manufacturing company, Eclatec, and the Jean Lamour Institute in Nancy. The overarching goal of this research is to enhance nighttime urban lighting while simultaneously reducing electrical consumption and light pollution. To achieve this, an RGB camera is integrated into the streetlamp's light source, serving as the primary data collection point. This choice necessitated the use of a wide-angle lens with a slight vertical tilt in its axis. Although this configuration allows for the observation of a significant portion of the illuminated area, it results in highly distorted images. From this system, four major research challenges were investigated:1. The first challenge concerns video detection of individuals in close proximity to the luminaire under very low lighting conditions, with the aim of achieving dynamic lighting adjustment. This detection relies on deep learning models from the Yolo family, which were fine-tuned through transfer learning using a specific collection of images. These images were captured at various locations in the Nancy metropolitan area, at heights ranging from 6 to 8 meters. Under conditions of 10 lux illumination, an aperture of f/3.5, and a fixed sensitivity of 3200 ISO, the detection rate for pedestrians and vehicles exceeds 97%. The model, implemented on the embedded NVidia Jetson Nano GPU, achieves a frame rate of approximately 10 FPS, which proves adequate for our application. 2. The second research direction explores the recognition of the environment surrounding the luminaire through semantic segmentation of images. This segmentation will subsequently be employed to adapt the light distribution of the LED matrix to the encountered urban scenario. To accomplish this, we employed the OCR-HRNet neural network, which enhances high-resolution segmentation by incorporating contextual representation that considers pixel aggregation. This architecture is well-suited to images of non-uniform surfaces, characteristic of the ground beneath the luminaire. The results demonstrate excellent identification of structures and vegetated areas. However, the distinction between sidewalk and road remains challenging, particularly when road surfaces exhibit similar reflectance and textures. A post-image virtual marking solution significantly improves segmentation accuracy, especially in sunny scenes with numerous shadowed areas. 3. In a third phase, we modeled the optical system to enable the estimation of the real-world positions of ground points based on their images. A simple Cam To World transformation is proposed, accounting for extrinsic parameters of the viewpoint (height, pitch, and resolution), and the lens distortion function, approximated as an equidistant projection law. Given that stringent precision is not critical, a rigorous system calibration was not conducted. For an effective observation zone of 20 m × 50 m, the localization error is on the order of meters. 4. Finally, we propose an avenue for utilizing the lighting infrastructure to analyze traffic flow fluidity. The proposed method analyzes apparent motion of users by estimating the mean optical flow within each bounding box detected by Yolo. Currently, optical flow determination is performed offline using the deep learning algorithm FlowNet2. In the range of 0 to 15 m/s, the estimated speed of the moving object exhibits an error of less than 1 m/s
Bourget, Pierre. "Coronographie à masque adaptatif pour imagerie et détection à haute dynamique." Thesis, Aix-Marseille, 2014. http://www.theses.fr/2014AIXM4375.
High contrast imaging of extra-solar planets and environments of bright astro- physical objects in general, such as stars, active galactic nuclei or objects of the Solar System is a challenging task. Different approaches are needed if the bright region to occult is optically resolved or not. We present the Adaptive Mask concept, observations on sky and numerical simulations show the usefulness of the proposed methods to optimize the efficiency of the coronagraphs for optically resolved or non resolved objects. Accessing small IWA is considered as an edge as it provides substantial scientific and technical advantages. One of the difficulties of accessing small IWA is that coronagraphs become very sensitive to low-order aberrations such as tip-tilt. Our original approach aims at integrating the small IWA capability and the mitigation of sensitivity to low-order aberrations within the coronagraph itself. Our concept is applicable to both low and high Strehl regimes, corresponding to current and next generation AO systems. The adaptive coronagraph can adapt dynamically, in quasi real time, to adjust to the observing conditions to deliver a stable and optimized contrast at the science image level. The mask adaptability both in size, phase and amplitude also compensates for manufacturing errors of the mask itself, and potentially for chromatic effects. The mask adaptability concept using a local phase modulation in the focal plane allows synchronous modulation for high dynamic range synchronous detection of a faint target immersed in a background. The coherence of the speckles with the central star is used to discriminate them from proper companions
Li, Wanjing. "Développement d'un système stéréoscopique adaptatif à l'aide de lumière structurée." Dijon, 2009. http://www.theses.fr/2009DIJOS026.
In the context of the 3D reconstruction of scenes by using active vision system, we propos two approaches of Regions Of Interest (ROI) localization in the scene. Once integrated in a commercial 3D scanner as pre-processing process, each approach would be capable to indicate the zones of scanning. In this way, the reconstruction time would be largely reduced, and the obtained point cloud would be much less important, whereas almost all pertinent date would be conserved. The first approach called “passive” is based on the 2D information of the scene. It consists in localizing, in the scene observed, the objects of specific type. This approach was developed under the assumption that the target objects have the shape of a tube. Firstly, several image processing tools are applied to determine contours of the tubes in the images; and finally, the scanning zones are determined in the space of the projector. This approach can be eventually generalized to apply to other types of forms. The second approach called “active” is based on the 3D information extracted from the scene by an iterative process. The process begins by a regular point pattern; based on the estimation of local surface curvature around each reconstructed 3D point, a new pattern is generated in order to project more points, during the next iteration, in the zones with strong curvature; as soon as the iterative process stops, the ROI can be determined in the space of the projector. The major advantage of this approach is that no constraint is necessary on the form of the ROI
Im Zusammenhang mit der 3D Rekonstruktion von Objekten mittels aktiver Projektion werden zwei Ansätze zur Detektion wichtiger Oberflächenbereiche für die Punktbestimmung vorgestellt. Die beiden Ansätze wurden mittels eines aktiven Stereosystems entwickelt. Im Falle einer Integration in kommerzielle 3D Scanner (Lasersystem, Projektionssystem) erlauben beide Ansätze den Messbereich im Sinne einer Vorverarbeitung auf die morphologisch relevanten Bereiche zu beschränken. Dementsprechend wird die Messzeit deutlich verkürzt, die Punktwolke erheblich verkleinert und trotzdem alles Wichtige erhalten. Der erste Ansatz basiert auf 2D-Daten des zu messendem Feldes. Dabei sind in diesen Daten die Messobjekte zu lokalisieren. Derzeit ist dieser Ansatz unter der Annahme realisiert, dass zu erfassende Objekte eine zylindrische Form haben. Die Wahl der Zylindergeometrie erfolgte dabei stellvertretend für andere denkbare Geometrien, auf die das Vorgehen einfach übertragen werden kann. Der zweite Ansatz fußt auf 3D-Daten, die in einem iterativen Prozess aus dem Messfeld gewonnen werden. Zunächst wird ein reguläres Muster auf das Objekt projiziert und mittels Stereotriangulation eine entsprechende 3D-Punktwolke erzeugt. In der Punktwolke wird für jeden Punkt die Oberflächenkrümmung im Raum ermittelt und in der Nachbarschaft von Punkten mit starker Krümmung ein neues, dichteres Muster projiziert. Der iterative Prozess ist beendet, sobald die verbleibenden Krümmungen unterhalb eines Grenzwertes liegen. Diese Methode eignet sie sich für die Digitalisierung von Innenbereichen in Gebäuden, über die man keinerlei a prioi- Information über die zu findenden Objekte besitzt
Fiorucci, Anne-Sophie. "Étude des mécanismes chromatiniens dans l’adaptation des plantes à la lumière." Thesis, Paris 11, 2014. http://www.theses.fr/2014PA112245.
Plants are sessile organisms that successfully face variations of the environment by taking advantage of their ability to adapt their physiology and morphology. In particular, light perception constitutes an essential source of information used throughout their life cycle to fine‐tune development. The work presented was aimed at studying the role of chromatin‐associated mechanisms on adaptive responses to light cues at two different timescales in the model plant species Arabidopsis thaliana. In a first part, the role of chromatin dynamics in the regulation of gene expression was assessed during de‐etiolation, a developmental transition of seedlings that is triggered upon the first perception of light. It focused mainly on the trimethylation of histone H3 at lysine 4 (H3K4me3), a post‐translational modification associated with transcriptionally active states. To gain new insights into this pathway, the SWD2‐Like b (S2Lb) gene was characterized and shown to represent a new partner of plant COMPASS‐like complexes and a major determinant of H3K4me3 in A.thaliana. Loss‐of‐function plant lines for the S2Lb gene revealed that a default in H3K4me3 enrichment correlates with impaired inducibility of several light‐responsive genes during de‐etiolation. The findings described here set the bases to investigating how this mark and the associated factors influence the modulation of gene expression in relation with other chromatin marks. The second part of this thesis was aimed at assessing the impact of epigenetic variation on the capacity of plants to undergo the shade‐avoidance response (SAR), an adaptive developmental response to unfavorable light conditions produced by competitors. A population of epigenetic Recombinant Inbred Lines (epiRILs), in which epigenetic variation (DNA cytosine methylation) is maximized and nucleotidic sequence variation is minimized, was used for a large‐scale phenotyping under two light conditions triggering opposite responses. The epiRIL population exhibited larger amplitude of phenotypic variation than wild‐type parents in each condition as well as a wider range of response to shade. A region at the beginning of chromosome 3 was identified by QTL mapping to specifically associate to the SAR. Though it remains to be characterized, the locus involved may represent a first “epigenetic QTL” influencing phenotypic plasticity in response to environmental changes
Florentin, Raphaël. "Propagation et contrôle adaptatif de la lumière amplifiée dans une fibre multimode." Thesis, Limoges, 2017. http://www.theses.fr/2017LIMO0069/document.
For a long time, multimode fibers were sparsely investigated because of the spatial and temporal distortions occurring during propagation across the fiber. Those distortions are consequences of mode coupling and modal propagation constant disparity. Although the propagation in a multimode waveguide is complex, it is deterministic and can be controlled by spatial shaping of the excitation. Considering an amplifying medium, the problem, at the heart of this thesis, is more complex because of nonlinear propagation due to heterogeneous gain saturation. Two kinds of Ytterbium doped multimode fiber amplifiers were tested: a step index fiber with a large core diameter and a coupled core multicore fiber. Spatial control of the output of the amplifier was achieved using a deformable mirror in combination with an iterative algorithm. In the case of a continuous wave excitation of the amplifier, we demonstrated that it was possible to confine light in a single-phase spot with a 2,8 W average power and 12 dB gain. We also demonstrated that the spatial shaping of the output has no effect on the amplifier gain. Furthermore, we obtained more complex output fields of multi-spot structure. Finally, focalization through the amplifying fiber was successfully demonstrated in femtosecond regime for which spatio-temporal couplings occur. A 120 kW peak power spot with a gain of 14 dB in a 350 fs pulse was obtained in a first experimental proof of concept. The spatial shaping allows also to control the duration of the amplified pulse by selection of modes with close group velocities
SIGNORATO, RICCARDO. "Optiques réflectives pour les lignes de lumière ESRF en mode actif/adaptatif." Université Joseph Fourier (Grenoble), 1997. http://www.theses.fr/1997GRE10302.
Caglar, Alper Harun. "Structures adaptatives en fonction de la lumière : DARMIN comme outil de génération d'ambiances architecturales dynamiques." Master's thesis, Université Laval, 2014. http://hdl.handle.net/20.500.11794/25448.
This research proposes a virtual environment as a device for morphological representation of luminous ambiances generated by an adaptive and dynamic structure, linking the relationship between the outside and inside at the stage of architectural conception. This developed tool called DARMIN « Daylight Adaptive aRchitecture Modeling INterface », becomes an exploratory inductor within the creative process through its interactive system. The designer, in typologically formal exploration phase, exploits the potential and qualities of architectural space that luminous ambiances harbors. In this way, the proposed research offers the possibility of the emergence of new complex morphological responses supporting the process of design. It also allows designers to experiment with a wide range of possible solutions in a virtual laboratory, controlled design environment that enhances the creativity of the architect. Thus, the presented research is particularly interested in showing the potential of adaptive architectural structure that quantitatively and qualitatively improves the experience of internal and external space through the dynamic nature of the luminous ambiances.
Langlois-Marcotte, Dominic. "Adaptation cinématographique de la nouvelle Femme de lumière de Claude Vallières : scénario, film, démarche de création et réflexion sur la lumière dans le film noir." Thesis, Université Laval, 2011. http://www.theses.ulaval.ca/2011/28116/28116.pdf.
Chanteloup, Jean-Christophe. "Contrôle et mise en forme des fronts de phase et d'énergie." Phd thesis, Palaiseau, Ecole polytechnique, 1998. http://tel.archives-ouvertes.fr/tel-00003131/en/.
La première partie est consacrée à la conception et la réalisation d'une boucle d'optique adaptative pour la correction des distorsions de surface d'onde sur la chaîne laser de puissance 100 Térawatts du Laboratoire pour l'Utilisation des Lasers Intenses. Cette boucle repose sur l'utilisation d'un dispositif à cristaux liquides comme modulateur de phase et d'un interféromètre à décalage comme senseur de front d'onde. L'association de ces deux dispositifs a permis la construction d'un système innovant de mesure et mise en forme de la surface d'onde d'impulsions lasers ultra-intenses. Il est démontré qu'il permet de corriger une surface d'onde présentant d'importantes distorsions et ainsi améliorer grandement la qualité de focalisation de faisceaux lasers. Cette boucle d'optique adaptative a été testée avec succès sur la chaîne 100 Térawatts et une correction de la surface d'onde de l'ordre de 60% a ainsi pu être démontrée.
La seconde partie du mémoire traite de la mise en forme d'une impulsion laser inhomogène brève permettant le pompage du milieu à gain (un plasma) d'un laser à rayons X. L'idée consiste à jouer sur le parallélisme du système de compression d'impulsions utilisé en fin de chaîne 100 Térawatts. Un modèle expliquant la génération d'une impulsion inhomogène laser brève à l'aide de ce compresseur à réseaux de diffraction est développé. Une campagne expérimentale Laser X a notamment permis de valider les prédictions théoriques annoncées par ce modèle et a montré la nécessité d'utiliser une telle impulsion inhomogène afin d'obtenir une émission laser X lorsque le pompage s'effectue par impulsion brève.
Bailleul, Benjamin. "Mécanismes de réponse à la lumière chez trois organismes photosynthétiques unicellulaires marins : Acaryochloris marina, Ostreococcus et Phaeodactylum tricornutum." Paris 6, 2009. http://www.theses.fr/2009PA066336.
Cartron, Leila. "Perception de la polarisation de la lumière chez la seiche Sepia officinalis : développement, fonction et approche comparative." Caen, 2012. http://www.theses.fr/2012CAEN2076.
Morin, Philippe-Israël. "Acclimatation à la nuit polaire puis au retour de la lumière chez la diatomée arctique Fragilariopsis cylindrus." Master's thesis, Université Laval, 2017. http://hdl.handle.net/20.500.11794/27908.
Polar winter in the Arctic can last as long as 6 months each year at high latitude. During this period, no light is available for photoautotrophic growth. Nevertheless, when light returns in spring, a sea-ice algae and phytoplankton bloom develops in the surface ocean layers. Therefore, the following questions can be asked: How do photoautotrophic communities (mainly diatoms) survive through winter darkness until light returns in spring? What are the physiological mechanisms underlying such survival? Our goal was to understand the acclimation processes at stake in both darkness and during the return to light by closely looking at the changes in intra-cellular content and functional capacity of a polar sea-ice diatom, Fragilariopsis cylindrus. We measured a set of parameters at specific time-points: the first days and first weeks up to 3 months of darkness, and the first hours up to 6 days upon return to light. This set included cell number and cytometry, cellular carbon and nitrogen quotas, lipid and pigment contents, fluorescence determinations, photosynthetic proteins (D1, RUBISCO), photosynthetic parameters and non-photochemical quenching (NPQ). A rather stable state was reached few days following transition to dark and was maintained throughout until the return of light: stable cell size and number, low energy reserve consumption, slow decrease of photosynthetic pigments and very low photosynthetic capacities. Subsequent transition to light after 1.5 months induced strong NPQ activity and reassembly/renewal of photosynthetic components, followed by metabolic recovery and cell growth. Transition after 3 months showed a much slower recovery and no cell growth, highlighting the increase of potential mortality with longer periods of darkness.
Massier, Sébastien. "Effets du traitement par la Lumière Pulsée sur la physiologie de Pseudomonas aeruginosa et d'Enterococcus faecalis." Rouen, 2011. http://www.theses.fr/2011ROUES030.
This work is devoted to the study of the bacterial response of Pseudomonas and Enterococcus genus against Pulsed Light treatment (PL). First, the characterization of the PL decontamination unit has chosen a configuration for achieving uniform treatment and to know the physical characteristics. On the other hand, very rapid kinetics destructions of bacterial cultures are obtained in this configuration (reduction of 9 logarithm units a few seconds). In this study, we showed that Pseudomonas aeruginosa is usually more sensitive than Enterococcus faecalis with respect to the same intensity treatment. However and interestingly Pseudomonas aeruginosa is able to adapt to a lethal treatment LP when subjected to sublethal PL doses. While Enterococcus faecalis showed a mutation rate increased after treatment. These different mechanisms used by bacteria in order to cope with the deleterious PL effects were identified by two-dimensional electrophoresis analysis to elucidate the molecular mechanisms involved in these responses
Sutour, Camille. "Vision nocturne numérique : restauration automatique et recalage multimodal des images à bas niveau de lumière." Thesis, Bordeaux, 2015. http://www.theses.fr/2015BORD0099/document.
Night vision for helicopter pilots is artificially enhanced by a night vision system. It consists in a light intensifier (LI) coupled with a numerical camera, and an infrared camera. The goal of this thesis is to improve this device by analyzing the defaults in order to correct them.The first part consists in reducing the noise level on the LI images. This requires to evaluate the nature of the noise corrupting these images, so an automatic noise estimation method has been developed. The estimation is based on a non parametric detection of homogeneous areas.Then the noise statistics are estimated using these homogeneous regions by performing a robust l`1 estimation of the noise level function.The LI images can then be denoised using the noise estimation. We have developed in the second part a denoising algorithm that combines the non local means with variational methods by applying an adaptive regularization weighted by a non local data fidelity term. Then this algorithm is adapted to video denoising using the redundancy provided by the sequences, hence guaranteeing temporel stability and preservation of the fine structures.Finally, in the third part data from the optical and infrared sensors are registered. We propose an edge based multimodal registration metric. Combined with a gradient ascent resolution and a temporel scheme, the proposed method allows robust registration of the two modalities for later fusion
PLATA, GOMEZ ARTURO. "Algorithmes de detection de phase dedies a l'interferometrie en lumiere polychromatique : application et apport des systemes adaptatifs a la profilometrie." Besançon, 1997. http://www.theses.fr/1997BESA2064.
Paquin, Éric. "Le récit épistolaire féminin au tournant des Lumières et au début du XIXe siècle, 1793-1837, adaptation et renouvellement d'une forme narrative." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape9/PQDD_0015/NQ43737.pdf.
Deslous, Paul. "Towards the characterization of regulators involved in the metabolism of ascorbic acid in tomato : Impact of environmental conditions on plant adaptation." Thesis, Bordeaux, 2018. http://www.theses.fr/2018BORD0372.
Ascorbic acid (AsA, vitamin C) is one of the most important biochemical in living organisms. Due to its high antioxidant potential, AsA represents an important trait of nutritional quality in fruits and vegetables. In addition to its beneficial health value in fruit consumption, increasing fruit AsA content would likely affect postharvest quality and resistance to pathogens. Thus, understanding the regulation of AsA accumulation in order to improve crop species of agronomical interest is an important issue in plant breeding for many fleshy fruit species. To get a better understanding of the regulation of AsA level in plants and its impact on fruit quality, a highly mutagenized EMS tomato collection (cv. Micro-Tom) was screened for AsA+ fruit mutants. This forward genetic strategy combined with a mapping-by-sequencing approach, had allowed identifying new genes related to the AsA+ trait. One of the mutant line named P21H6, displayed an AsA-enrichment 2 to 4 fold that of the WT, and was the first to be genetically characterized. It allowed highlighting a new class of photoreceptor involved in blue light sensing named SlPLP as a negative regulator of AsA accumulation in tomato. We confirmed the role of the PLP in the fruit AsA+ phenotype using a directed mutagenesis strategy, undertaking its functional characterization. We demonstrate that PLP interacts with GGP (GDP-L-galactose phosphorylase), a key enzyme of the L-Galactose pathway, under blue light control and that this interaction takes place in the cytoplasm and the nucleus. Our results strengthen the central role of GGP in the AsA biosynthesis and suggest a new regulation mechanism by blue light of the GGP function in addition to its metabolic activity. Besides we started the characterization another mutant, the P17C5-3, which displayed the highest level of AsA (up to 10 times the WT). Beyond its AsA+ content, the P17C5 mutant showed strong morphological alterations including a seedless phenotype making the mapping difficult at first. Thanks to the crossing with the commercial M82 tomato cultivar, the causal mutation was identified in a cis-acting ORF, upstream of the GGP gene. This result confirmed the key role of GGP in the L-Galactose pathway. Preliminary studies related to the parthenocarpic phenotype suggest a problem of male sterility associated with pollen development processes. Finally, in the study of the post-harvest fruit quality, chilling stress experiments carried out with the P21H6 fruits seem to demonstrate that increasing AsA content improve the fruit shelf life and its maturation capacity. Taken as a whole, our results confirmed the key position of the GGP protein in the AsA biosynthesis pathway and they provided precious tools and plant material for deciphering the regulation of AsA and its physiological role in fruit quality and post-harvest traits
Pensieri, Pasquale. "Rôle d'Otx2 dans les photorécepteurs de la rétine mature." Thesis, Université Côte d'Azur (ComUE), 2019. http://www.theses.fr/2019AZUR6038.
Although the role of Otx2 transcription factor in retinal development is well understood, its function in the adult retina remains unclear. Otx2 expression is maintained in Retinal Pigmented Epithelium (RPE), photoreceptors (PRs) and bipolar cells throughout life. Previous works from our lab showed that Otx2 ablation in the adult retina leads to photoreceptor degeneration, suggesting a role in their maintenance. It was then showed that RPE-restricted Otx2 expression was both necessary and sufficient for photoreceptor maintenance, indicating a non-cell-autonomous neuroprotective function. This left unexplained the function of endogenous Otx2 in PRs. In order to elucidate it, we performed PR-specific Otx2 knockout, using the inducible PR-specific Crx-CreERT2 mouse line. Histology confirmed that endogenous Otx2 is not required for PR survival or maintenance of their cell identity in the adult. However, we found that Otx2 is implicated in visual adaptation, by regulating the light induced movement of arrestin in photoreceptors. Arrestin shuttles between PR outer segments, where it accumulates in the light, and inner segments and soma, where it accumulates in the dark, to modulate PR sensitivity, in response to different light intensities. Such trafficking is compromised in PR-specific Otx2 KO mice, where arrestin remains blocked in inner segments and soma, even after prolonged light exposure. Behavioural tests showed that PR-specific Otx2 KO mice are strongly photophobic. The detailed mechanisms remain to be elucidated.To decipher the genetic network controlled by Otx2 in PRs, we carried out time series RNA-seq analyses following PR-specific Otx2 knockout. No photo-transduction gene was found to be deregulated. Instead of that, we found down-regulation of extracellular matrix genes and, surprisingly, of a group of RPE-specific genes involved in melanogenesis, genes that were already known to be direct targets of Otx2. Careful examination of PR-specific Otx2 KO mice confirmed that Otx2 protein level in the RPE nuclei was reduced while some Otx2protein could now be detected in PR outer segments. According to such data and to the neuroprotective effect of RPE-restricted Otx2, we hypothesized a direct Otx2 protein transfer from RPE to PRs. To prove this hypothesis, viral vectors driving tagged-Otx2 expression specifically in RPE cells were generated and used for sub-retinal injection in mice. After RPE transduction, tagged-Otx2 could be detected in the PRs. We found that in wild type retina, constitutive Otx2 transfer is active at low rate. After KO induction in the PRs, the transfer rate is increased, probably acting as a neuroprotective response. Such increment in the transfer explains well the reduction of Otx2 protein level in the RPE and the subsequent downregulation of melanogenesis genes. Transferred Otx2 appears to travel across PR cells from the inner and outer segments to the synapse in the outer plexiform layer, suggesting its neuroprotective function involves mechanisms that are different from its classical genomic function of transcription factor.In conclusion, this study disclosed a new function of endogenous Otx2 in PR light adaptation and demonstrated the existence of a transfer of Otx2 from RPE to PR cells, with a putative neuroprotective role
Humbert, Lionel. "Tolérance et largeur de niche des espèces herbacées des forêts québécoises vis-à-vis du PH et de la lumière." Mémoire, 2006. http://www.archipel.uqam.ca/3175/1/M9466.pdf.
Paquin, Éric. "Le récit épistolaire féminin au tournant des Lumières et au début du XIXe siècle (1793-1837) : adaptation et renouvellement d'une forme narrative." Thèse, 1998. http://hdl.handle.net/1866/6765.
Dubouchet, Renaud Adrien. "Une approche fréquentielle pratique pour l'échantillonnage adaptatif en espace image." Thèse, 2014. http://hdl.handle.net/1866/12834.
In realistic image synthesis, a pixel's final intensity is computed by estimating a multi-dimensional shading integral. A large part of the research in this domain is thus aimed at finding new techniques to reduce the computational cost of rendering while preserving the fidelity and correctness of the resulting images. When trying to reduce rendering costs to approach real-time computation, complex realistic effects are often left aside or replaced by clever but mathematically incorrect tricks. To accelerate rendering, previous directions of work have either addressed the computation of individual pixels by improving the underlying numerical integration routines; or have sought to amortize the computation across regions of an image using adaptive methods based on predictive models of light transport. This thesis' - and resulting paper's - objective is to build upon the latter of the aforementioned classes of methods[Durand2005], and foray into fast adaptive rendering techniques using frequency-based light transport analysis to efficiently guide and prioritize ray tracing. We thus propose an adaptive sampling and reconstruction approach to render animated scenes lit by environment lighting and faithfully reconstruct all-frequency shading effects such as shadows and reflections while preserving temporal coherency.