Le contrôle des polluants environnementaux présents à faible concentration a conduit à la création de détecteurs miniaturisés, à bas coûts et ultra-sensibles, capables d’identifier spécifiquement certaines substances. Dans cette thèse, la méthode de détection explorée repose sur la sensibilité de micro-lasers polymères à une variation d’indice de réfraction. Cette approche a été mise en application pour détecter des métaux lourds (mercure – Hg2+, cadmium – Cd2+ et plomb – Pb2+) dans l’eau potable. En effet les fréquences de résonance de ces micro-cavités sont particulièrement sensibles à l’indice de réfraction du milieu extérieur et se déplacent lorsque celui-ci est modifié. Ce système permet ainsi une détection sans marqueur (« label ») en recouvrant la cavité d’une couche de reconnaissance spécifique de l’espèce recherchée. L’originalité de ce travail repose sur l’utilisation de micro-cavités actives, ou micro-lasers, fabriquées avec des polymères dopés par des colorants lasers. En effet les micro-lasers permettent d’augmenter le rapport signal/bruit et de profiter de pics de résonance étroits, même pour des facteurs de qualité de l’ordre de quelques milliers seulement. Le choix de matériaux organiques comme milieu à gain a été dicté par les nombreux avantages qu’ils offrent. Contrairement aux semi-conducteurs inorganiques, les polymères peuvent être fonctionnalisés de manière relativement aisée et l’utilisation de matériaux poreux devrait augmenter la sensibilité en faisant circuler le fluide à tester à l’intérieur même du résonateur. De plus le protocole de fabrication des micro-lasers organiques reste d’un coût modéré et permet une intégration aisée en micro-fluidique. Deux voies différentes ont été explorées dans cette thèse : détection d’une variation d’indice de réfraction avec des cavités non-fonctionnalisées et détection d’ions lourds avec des cavités fonctionnalisées. Dans le premier cas, la sensibilité obtenue est comparable à ce qui est publié pour des micro-résonateurs passifs. Dans le second cas, nous avons réussi à mettre en évidence la présence d’ions mercure jusqu’à 10-6 M. Quelques approches ont été envisagées pour diminuer encore le seuil de détection dont certaines ont été vérifiées expérimentalement. Ainsi, cette étude propose un prototype de composant sur puce pour la détection d’espèces chimiques ou biologiques. / Monitoring of environmental pollutants present at low concentrations requires creation of miniature, low-cost, and highly sensitive detectors that are capable to specifically identify target substances. In this thesis, a detection approach based on refractive index sensing with polymer micro-lasers is proposed and its application to the detection of heavy metal pollutants in water (mercury – Hg2+, cadmium – Cd2+ and lead – Pb2+) is studied. The resonance frequencies of the microcavity are highly sensitive to the refractive indices of the resonator surrounding: the resonances shift by a small amount when the surface refractive index changes, resulting from the interaction of the mode evanescent field with the surrounding medium. This permits label-free detection by coating the resonator with a suitable recognition species. The originality of this work lies in the utilization of active microcavities, or microlasers, created of the dye-doped polymers. Active microcavities offer an enhanced signal/noise ratio as compared to the passive ones and very narrow resonance peaks even at moderate quality factors (Q &#8805- 6000). The choice of polymers as an active medium is connected with a number of advantages they offer: as opposite to semiconductors, polymers can be easily functionalized, integrated in microfluidic circuits and are cheaper in processing. Moreover, the use of porous polymer matrices may allow accumulation of analyte ions inside the microcavity and thus enhance the sensitivity. Two possible applications of microlasers are investigated in the thesis: refractive index variation sensing with non-functionalized cavities and heavy metal ion detection with functionalized cavities. In the first case, the sensitivity values have been obtained, comparable with the reported in literature for planar passive microresonators. In the second case, the experimental proofs of specific detection of mercury ions in liquid are presented. The ways of sensitivity improvement are discussed and verified and a foundation is layed for the creation of integrated Lab-on-Chip microfluidic biochemical detector.

La production de masse de cavités accélératrices supraconductrices en régime radiofréquence (SRF) est un réel défi industriel non seulement du fait du nombre croissant de cavité pour les futurs grands projets mais également de par les besoins en terme de fiabilité, reproductibilité et performances demandées très proches des limites physiques du Niobium. De nos jours, XFEL (DESY) et le LHC (CERN) sont les deux accélérateurs les plus importants utilisant la technologie supraconductrice. Des projets accélérateurs encore plus ambitieux, tels que l’ILC (International Linear Collider) et FCC (Future Circular Collider) sont en cours d’étude. Pour de tels projets, il est encore nécessaire d’améliorer les performances et de réduire les coûts de fabrication et d’opération avant d’engager la phase d’industrialisation.Une voie d’amélioration des performances et de réduction des coûts a été étudiée. Ceci consiste à améliorer les procédés de nettoyage des surfaces. En effet, la pollution et les dommages causés à la structure cristalline durant la fabrication d’une cavité supraconductrice doivent être impérativement retirés afin de garantir des performances optimales. Cette régénération des surfaces est couramment réalisée à l’aide de deux types de polissages chimiques : par BCP (Buffered Chemical Polishing) ou par électro-polissage (EP). Cependant, ces techniques utilisent des acides très concentrés qui entrainent des coûts d’opération très conséquents du fait des problèmes de sécurité. Une voie d’amélioration pouvant rendre possible la construction de telles machines serait de remplacer totalement ou partiellement l’utilisation des acides par des techniques de polissage alternatives.Le polissage mécanique a été étudié durant des décennies et plus spécifiquement les techniques par centrifugation (CBP). Cette technique permet d’atteindre des rugosités de surface bien meilleures et est bien plus efficace pour retirer certains défauts de surface comparé aux procédés chimiques. Cependant, cette technique n’est pas envisageable comme solution alternative à cause des fortes pollutions de surface et des durées de traitement très longues. La première partie de la thèse a consisté à reproduire l’état de l’art, comprendre les limitations réelles de cette technique et essayer d’améliorer le procédé en réduisant la pollution de surface générée par le piégeage des abrasifs en surface ainsi que la durée de traitement (réduction du nombre d’étapes intermédiaires). Il a été conclu que ce procédé ne peut pas être considéré comme alternatif mais complémentaire aux traitements chimiques.La deuxième partie du travail de thèse s’est concentrée sur la méthode de polissage métallographique. Cette dernière ne peut s’appliquer que sur plaques et non sur des géométries complexes, cependant elle retire très efficacement toutes les impuretés et dommages cristallins formés durant la fabrication des tôles de Niobium. Un procédé optimisé à 2 étapes, inspiré des techniques conventionnelles (typiquement 5-6 étapes) a été développé avec succès et optimisé pour les contraintes particulières du Niobium pour les applications SRF. Ce procédé permet non seulement d’obtenir une rugosité de surface incomparable mais préserve également la structure cristalline. Des études complémentaires sont encore requises afin d’améliorer les techniques de formage des tôles ou même caractériser des solutions alternatives permettant des limiter les dégâts en surface et de préserver la qualité du matériau.Finalement, ce travail mené est d’une importance capitale pour le futur des cavités accélératrices supraconductrices, c’est-à-dire l’utilisation de nouveaux matériaux supraconducteurs sous forme de couche mince. La qualité des couches minces de ces matériaux alternatifs dépend très fortement de l’état de surface du substrat (typiquement niobium ou cuivre poly cristallin). / Large-scale production of superconducting radio-frequency (SRF) cavities is an industrial challenge, not only because of the increasing number of unit for future projects but also because of requirements in term of reliability, reproducibility and performances very close to the physical limit of polycrystalline bulk Niobium. Nowadays, XFEL (DESY) and LHC (CERN) are the largest existing accelerators which are based on SRF technology. Even more challenging SRF accelerator projects like ILC (International Linear Collider) and FCC (Future Circular Collider) are being studied. For such large-scale facilities, higher performances, reduction in fabrication and operation costs are required and essential to proceed with industrialization.A pathway to reduce these costs and improve performances has been studied in this work. It consists in optimizing the cleaning process of cavity surfaces. Indeed, pollution and crystal defects on the surface created during fabrication steps of a SRF cavity have to be removed to ensure optimal superconducting performances. In order to get rid of impurities and to recover crystal structure, two polishing techniques are routinely used: the buffered chemical polishing (BCP) and electro-polishing (EP). However, these techniques involve highly concentrated acids, which lead to high operation costs and safety concerns. A way to overcome the aforementioned drawbacks and make the construction of future accelerators possible would be to replace or complement the conventional chemical polishing by alternative polishing techniques.Mechanical polishing has already been applied in SRF-community for decades by using centrifugal barrel polishing (CBP). This technique could provide a better surface roughness and could be more efficient at removing some surface defects compared to EP and BCP. However, this process does not satisfy requirements for large-scale production due to strong surface pollution and an extremely long processing time. The first part of the PhD work consisted in reproducing the state of the art, understanding its limitations and optimizing the recipe by the reduction of the surface pollution (embedded abrasives) and processing time (reduction of intermediate steps). As a conclusion to this first study, CBP could only be a complementary polishing technique to chemical treatments.The second part of the work focused on metallographic flat polishing. This technique cannot be directly applied on enclosed geometries however, it can remove efficiently surface defects (impurities and crystal damages) created during the fabrication of Niobium sheet. A 2-step process, inspired from metallographic techniques (typically 5-6 steps) has been successfully developed and optimized on Niobium for SRF applications. This process provides not only an improved roughness compared to conventional chemical treatments but also preserve the crystal quality underneath the surface, over the field penetration depth. Additional studies have to be now carried out to optimize conventional forming process or characterize alternative techniques to limit surface damages and preserve material quality as much as possible.Last but not least, the work done is of first importance for the future of SRF cavities meaning the use of new superconducting materials as thin films. The quality of thin-films of alternative superconductors depends strongly on the surface state of the substrate, typically polycrystalline bulk Niobium or Copper.

Birds may have the ability to view their environments at a wide range of spatial scales; accordingly, they may make habitat-selection decisions at multiple spatial scales. I investigated the implications of hierarchy theory and a landscape perspective on nestsite selection in cavity-nesting birds in the Uinta Mountains in northeastern Utah. I used · three different approaches to address the concept of a multi-scaled nest-site selection Ill process. First, I conducted an exploratory study in which I investigated nest-site selection at three spatial scales for Red-naped Sapsucker (Sphyrapicus nuchalis), Northern Flicker (Colaptes auratus), Tree Swallow (Tachycineta bicolor), and Mountain Chickadee (Parus gambeli). By conducting a hierarchically structured analysis, I was able to investigate the habitat relationships that might result from a hierarchically organized nest site selection process . I found that the four species were associated with patterns of vegetation at three spatial scales and that these associations combined in such a way as to imply a process of nest-site selection that may be more complex than that posited by the niche-gestalt concept. Second, I conducted an experiment in which I investigated nest-site selection at two spatial scales. I compared the use of four types of aspen stands in a two-by-two factorial design according to within-stand structure and landscape context. Stands were classified as either dense or sparse and as having predominantly meadow or forested edges. To address nest-site selection by secondary cavity nesters , who may be limited by cavity availability, I augmented the natural cavities with nest boxes. I found that birds predominantly nested in sparse stands and in stands with meadow edges. Although only five nest boxes were used for nesting, all five of these boxes were in sparse stands with meadow edges. The third way in which I investigated the process of nest-site selection was to build and test predictive models using associations between birds and landscape patterns. By using landscape patterns to predict habitat, I was able to build models that were easily applied ; predictions could be made without any additional data collection in the field. The models were very accurate for both Red-naped Sapsuckers and Tree Swallows (86- 98% and 53-93% nests correctly predicted, respectively) but were less accurate for Mountain Chickadees and Northern Flickers (33-42% and 19-37%, respectively) .

When a sphere or a stream of water hits the surface of a pool of water and enters a crater or air cavity often forms. This topic has been studied, both formally and informally, for a long time. This dissertation investigates four areas of water impact that are still poorly understood using high-speed photography. First, it examines a stream of droplets impacting on a pool of water, similar to a faucet drizzling into a full bucket. For these types of impacts we predict the depth, diameter, velocity, and shape of the cavities that the droplet stream forms. Second, it examines what occurs when a sphere impacts a pool of soapy water, such as a bubble bath or kitchen sink. The minimum velocity for a cavity to form decreases when soap is present. If the water has bubbles on the surface, the sphere will always form a cavity. Third, it examines how different coatings on a sphere (car wax, etc.) affect whether the sphere forms a cavity, and it shows how the coating affect the shape of that cavity. Fourth, when objects impact a water surface they experience a large force, which many people have noticed when participating in cliff jumping, high diving, and belly flop competitions. We show that the force of impact can be reduced by 75% simply by allowing a mass of water to impact in front of the object.

La capacité des sources laser à concentrer une quantité d’énergie énorme intéresse beaucoup le secteur industriel pour l’usinage et la structuration de la matière. Il faut pour cela rassembler une forte puissance optique sur une surface infime: on parle alors de luminance. La combinaison cohérente permet de répondre à la problématique de l’augmentation de la luminance d’un système laser. Dans le cadre du projet européen BRIDLE, ces travaux sont focalisés sur la combinaison cohérente de lasers à semi-conducteur. Ce type de combinaison nécessite un accord de phase stable entre les différents émetteurs. Plusieurs techniques permettent cette mise en phase; nous étudions en particulier les techniques d’amplification en parallèle ainsi que l’utilisation d’une cavité externe commune. L’originalité se situe dans le développement d’une architecture nouvelle, pensée pour optimiser l’extraction de puissance. La technique consiste à utiliser une cavité étendue commune aux émetteurs à combiner pour leur mise en phase, placée sur leur face arrière. Tout en fournissant un fort retour optique arrière nécessaire à la mise en phase, l’extraction de puissance est maximisée sur la face avant où les faisceaux sont par la suite combinés extracavité. Ce document démontre la bonne adéquation de cette architecture avec les meilleures diodes laser en termes de luminance : les émetteurs à section évasée. L’étude est étendue à une barrette de diodes par l’utilisation d’éléments diffractifs optique permettant la séparation et la combinaison des faisceaux. / Scaling up the brightness of laser diodes is a major research objective in the laser community. The coherent beam of several emitters is the most efficient technique to increase the brightness by constructive interference. An efficient combination can only be achieved in an arrangement that forces the required phase relation between the emitters. Different approaches are investigated: either active phase-locking of amplifiers seeded by a single-frequency laser split into N beams and amplified in parallel, or passive selforganization of emitters in a common laser cavity. We investigate a new coherent combining architecture using a common extended cavity on the back side of diode lasers for phase locking. As a result, the efficiency of the phase-locked laser cavity is increased as compared to standard front-side configurations. Moreover, such an extended cavity placed on the rear-side provides the strong optical feedback required for phase-locked operation. This configuration is demonstrated with high-brightness tapered devices, highlighting the capability of such setup for high power operation. This architecture is then extended to diode laser arrays by the use of diffractive optical elements.

Nonthermal plasma-assisted combustion (PAC) has been demonstrated to be a promising potential method to enhance combustion performance and reduce the pollutant emissions. To better understand the mechanism in PAC, we have conducted a series of studies on the combustion enhancement by plasma using a home-developed PAC platform which employs a nonthermal microwave argon plasma and a suit of optical diagnostic tools including optical imaging, optical emission spectroscopy, and cavity ringdown spectroscopy. A new PAC system in which a continuous atmospheric argon microwave plasma jet is employed to enhance combustion of methane/air mixtures was reported. Reactive species in PAC were characterized in a state-resolved manner including the simultaneously measurements of OH(A) and OH(X) radicals in the PAC flames. Roles of the state-resolved OH(A) and OH(X) radicals in microwave PAC of premixed methane/air mixture were explored. It was concluded that if both OH(A) and OH(X) radicals assisted the ignition and flame stabilization processes, then we may hypothesize that the role of OH(A) was more dominant in the ignition enhancement but the role of OH(X) was more dominant in the flame stabilization. The effect of fuel injection configurations was investigated in the comparative study between PAC of the premixed and nonpremixed methane/air mixtures. It was found that emissions from the CH (A-X) and C2 Swan systems only exist in the nonpremixed PAC which suggest that the reaction pathways are different between premixed and nonpremixed PAC. The PAC of premixed methane/oxygen/argon mixtures was investigated. A U-shaped dual-layer curve of fuel ignition/flame stabilization limit showing the effects of the plasma power on the fuel ignition and flame stabilization was observed and reported. A parametric study of the microwave PAC of the premixed ethylene/air mixtures was conducted. Behavior of the OH, CH, and C2 radicals and their dependence on plasma power, argon flow rate, and total ethylene/air mixture flow rate were also studied.

京都大学 / 新制・課程博士 / 博士(医学) / 甲第24129号 / 医博第4869号 / 新制||医||1059(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 平井 豊博, 教授 中島 貴子, 教授 森本 尚樹 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

Rafinesque’s big-eared bats (Corynorhinus rafinesquii; RBEB) and southeastern myotis (Myotis austroriparius; SEM) are listed on IUCN Red List of Threatened Species. Limited information on roost sites exists. I conducted roost surveys for RBEB and SEM on public forest lands in central Mississippi during winter and spring 2010. During winter, RBEB and SEM roosted in cavity trees with greater trunk diameters. In spring, roost trees used by SEM were located in forested areas of lower elevation, less slope, and greater distances from roads. Because imperfect detection can affect occupancy estimates, I estimated detection probabilities under different survey methods. Detection probability ranged from 95 – 100% and 92 – 99% when one to 2 observers used repeated surveys and removal method, respectfully. When estimating for abundance, presence of ≤20 bats led to count errors of <4%. When >20 bats were present, count errors were 38.1%. Observers correctly identified species 91% of the time.

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