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Les avancées de la génomique montrent que les êtres vivants produisent de nombreux long ARNs noncodant, dont les fonctions restent globalement mal connues. Des données récentes indiquent que ces long ARNs apparemment noncodants peuvent cependant traduire des peptides à partir de petits cadres ouverts de lecture (smORFs). Si différentes approches établissent l'existence de ces smORF peptides, un enjeu important est d'élucider leur mode d'action et de déterminer s'ils peuvent participer à la régulation du développement. Notre équipe étudie le développement de l'épiderme chez la drosophile. Des travaux antérieurs ont bien établi le rôle clé d'un facteur de transcription, OvoL/Shavenbaby (Svb), qui gouverne la différenciation des cellules à trichomes de l'épiderme. Des études récentes de l'équipe ont permis d'identifier le répertoire des gènes cibles de Svb, qui codent différents effecteurs cellulaires collectivement responsables de la formation des trichomes. De manière inattendue, la différentiation des trichomes nécessite aussi la fonction d'un ARN atypique: polished rice / tarsal less / mille pattes (pri). Initialement découvert comme un long ARN noncodant, pri agit en réalité par la production de quatre smORF peptides (11-32aa). Une collaboration internationale a permis de démontrer que les peptides Pri induisent une maturation post-traductionnelle de la protéine Svb, la transformant d'un répresseur à un activateur de transcription. Ainsi, alors que l'expression de Svb définit le registre spatial des cellules à trichome, les peptides Pri sont requis pour mettre en route le programme transcriptionnel de leur différenciation. Si les travaux de l'équipe viennent d'identifier les mécanismes moléculaires de l'activation de Svb par les peptides Pri, la logique développementale de cette régulation complexe restait à explorer. Pour aborder cette question, mes travaux de thèse ce sont concentrés sur la recherche des mécanismes transcriptionnels contrôlant l'expression du gène pri. En effet, cette problématique apparaissait particulièrement importante car c'est finalement l'expression de pri qui va déclencher la formation des trichomes dans les cellules Svb positives. Dans une première étape, j'ai utilisé une série de chromosomes bactériens artificiels introduits chez la drosophile pour délimiter l'étendue du locus génétique indispensable à la fonction de pri. Bien que pri code un ARN sans intron d'environ 1,5 kilobases (kb), mes test génétiques ont montré que l'unité fonctionnelle du gène pri s'étend sur plus de 50kb ! J'ai construit une batterie de lignées transgéniques rapportrices, qui ont permis d'identifier un ensemble de régions cis-régulatrices distinctes, dirigeant l'expression de pri dans différents tissus et stades de développement. / Recent advances in genomics have revealed that most species produce a broad variety of long non-coding RNAs, whose functions remain generally not well understood. A growing body of evidence yet indicates that apparently non-coding RNAs can often encode peptides from small Open-Reading Frames (smORFs). While additional data clearly support their translation in cells, an important issue is to elucidate the putative mode of action of smORF peptides and whether these peptides could contribute to the regulation of differentiation or development. Our team is studying the development of epidermal derivatives in flies. Previous work has identified a key transcription factor, OvoL/Shavenbaby (Svb) that governs the differentiation of epidermal trichomes, which are cuticle extensions contributing to different aspects of the insect life. Svb is both required and sufficient to determine trichome formation, and thus Svb expression defines which subsets of cells form trichomes. Recent studies showed that Svb directly activates the expression of a large number of genes encoding cellular effectors, collectively responsible for trichome differentiation. Unexpectedly, trichome formation also requires an atypical RNA, called polished rice/ tarsal less/ mille pattes (pri), which was initially considered as non-coding but that acts through the production of four smORF peptides (11-32aa). The absence of pri leads to embryos lacking any trichomes, as seen following the inactivation of Svb, thus suggesting a functional interaction between Pri & Svb. Indeed, a collaborative work has demonstrated that Pri peptides induce a post-translational maturation of the Svb protein, switching its activity from a transcriptional repressor to an activator. Therefore, whereas Svb expression defines the spatial pattern of epidermal cells forming trichomes, Pri peptides are required to turn ON the genetic program of trichome differentiation. While recent work in the team now unravels the molecular mechanisms by which Pri peptides achieve Svb maturation, the developmental rationale of such a complex process remained to be explored. To address this question, the aim of my PhD has been to investigate the transcriptional control of pri expression. This issue appeared important since this is ultimately the onset of pri expression that defines when the transcriptional program of trichome is executed, in Svb positive cells. In a first step, I used a series of bacterial artificial chromosomes to functionally delineate the extent of the pri genetic locus. Although pri is an intron-less RNA of approx. 1.5kb, rescuing assays showed that pri function relies on distant genomic regions, spanning more than 50 kb. Using a battery of in vivo reporter constructs, I then characterized pri genomic regions and found that they include a large array of cis-regulatory regions driving pri expression in different tissues, and at several stages of embryonic and post-embryonic development. In collaboration with other members of the team, our studies further demonstrate that pri expression is regulated by the ecdysone steroid hormone, a signaling pathway well known for providing a temporal control of developmental transitions. We collected a set of complementary pieces of evidence showing that the Ecdysone Receptor activates the expression of pri, directly binding to different enhancers that drive various spatiotemporal patterns of pri expression. All together, these data establish that a main role of pri is to mediate the systemic signal of steroid hormone to precisely time the execution of epidermal differentiation, at the successive stages of Drosophila development. This allows us to explain the developmental importance of Pri peptides in the temporal control of epidermis differentiation, and additional results suggest a broader implication of Pri in implementing ecdysone signaling for the timing of different programs of development.

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Side-polished fiber allows access to the evanescent field propagating in the cladding of a few-mode fiber. This cladding mode is analyzed and experimentally validated to further the design of a novel class of fiber optic devices. To do this, specific modes are excited in the polished fiber using a phase-only spatial light modulator to determine spatial mode distribution. Each mode is excited and compared to the expected field distribution and to confirm that higher order modes can propagate through side-polished fiber. Based on each mode’s distribution, a side-polished fiber can be designed so that perturbations on the polished portion of the fiber effect each mode independently. By carefully analyzing the effects of identical perturbations on each mode, it is determined that each mode can be isolated based on the geometry of the polished fiber and careful alignment of the mode field. This research has the potential to advance the development of novel fiber-based sensors and communications devices utilizing mode-based interferometry and mode multiplexing. / M.S. / Fiber optic devices have seen significant advancement since the realization of the laser and low-loss optical fiber. Modern day fiber optics are commonly utilized for high-bandwidth communications and specialized sensing applications. Utilizing multiple modes, or wave distributions, in a fiber provides significant advantages towards increasing bandwidth for communications and provides potential for more accurate sensing techniques. Significant research has been conducted in both the sensing and communication field, but mode-domain devices have the capability to significantly advance the field of fiber optic devices. This thesis demonstrates the potential for side-polished fiber geometry to effect each mode independently, thus allowing side-polished fiber to be utilized for realizing novel devices such as multiplexing devices and fiber optic sensors.

Several next generation astronomical telescopes or large optical systems utilize aspheric/freeform optics for creating a segmented optical system. Multiple mirrors can be combined to form a larger optical surface or used as a single surface to avoid obscurations. In this paper, we demonstrate a specific case of the Daniel K. Inouye Solar Telescope (DKIST). This optic is a 4.2 m in diameter off-axis primary mirror using ZERODUR thin substrate, and has been successfully completed in the Optical Engineering and Fabrication Facility (OEFF) at the University of Arizona, in 2016. As the telescope looks at the brightest object in the sky, our own Sun, the primary mirror surface quality meets extreme specifications covering a wide range of spatial frequency errors. In manufacturing the DKIST mirror, metrology systems have been studied, developed and applied to measure low-to-mid-to-high spatial frequency surface shape information in the 4.2 m super-polished optical surface. In this paper, measurements from these systems are converted to Power Spectral Density (PSD) plots and combined in the spatial frequency domain. Results cover 5 orders of magnitude in spatial frequencies and meet or exceed specifications for this large aspheric mirror. Precision manufacturing of the super-polished DKIST mirror enables a new level of solar science.

Yes / Confocal microscopy has been increasingly employed in the field of traceology to acquire metrological data of surface changes on a micro-scale. However, its advantages for a traditional visual inspection of use-wear are rarely highlighted. As traditional optical microscopy (OM) has proven unable to entirely fulfil the prerequisites for an ideal observation of highly reflective and irregular materials, alternative ways for providing better observation conditions must be sought. In this contribution, we explore the combination of laser scanning confocal (LSCM) and scanning electron microscopy (SEM) micro-graphs for the visual characterisation of wear on quartzite and evaluate the potential of both techniques. / AHRC Fragmented Heritage project (AH/L00688X/1) at the University of Bradford, and of the MICINN-FEDER (PGC2018-093925-B-C32), the AGAUR (SGR 2017-1040) and the URV (2018PFR-URV-B2-91) projects at IPHES-URV. One of the authors (A.P.) was beneficiary of a Catalan pre-doctoral grant (2014FI B 00539), at the Rovira i Virgili University (URV), the IPHES and the Muséum national d’Histoire naturelle of Paris.

Une étude expérimentale est menée afin de comprendre le phénomène de nucléation lors de l'ébullition. Cette étude est menée sur des surfaces polies miroir ou ultra-polies en aluminium, l’acétone étant le fluide de travail. L'analyse est réalisée en fonction de la topographie de la surface liée au degré de polissage et en fonction du revêtement de la surface dans le but de modifier sa mouillabilité. L’étude a mis en avant trois catégories de comportement, fonctions de l’état de surface : les surfaces nano lisses, les surfaces nano lisses avec défauts et les surfaces rugueuses. Les bonnes caractéristiques obtenues avec des échantillons nano lisses comportant des défauts aléatoirement répartis ont conduit à la réalisation d’échantillons nano lisses avec des défauts de position et de taille contrôlés. Les résultats obtenus avec ces derniers échantillons présentent les meilleures performances. Une amélioration supérieure à un facteur deux par rapport aux surfaces rugueuses est observée, ce qui représente un gain substantiel. Bien qu’il soit le fondement de la plupart des modèles théoriques, le nucléus à l’origine de la formation d’une bulle n’a jamais été observé expérimentalement car sa taille dépasse la capacité des moyens de mesure traditionnels. Dans ce mémoire, une méthode optique - basée sur la résonnance de plasmons sur des surfaces comportant un réseau de diffraction - est utilisée dans le but d’étudier ce phénomène. Les expériences mettent en évidence la capacité de cette méthode à mesurer la variation de la température pariétale de l’échantillon avant le déclenchement de l’ébullition. Les mesures de résonance plasmon montrent qu’il n’y a pas de modification de la densité du fluide au voisinage de la paroi pour des surchauffes proches du déclenchement de l’ébullition. La nucléation est trop rapide pour être mesurée. Cependant, des premiers nuclei de condensation ont été détectés par cette méthode, ce qui constitue un résultat très prometteur. / An experimental study was conducted in order to understand the phenomenon of nucleation in boiling. This study was done on smooth surface or ultra-smooth surface made of aluminum, the working fluid is acetone. The analysis was realized as a function of the topography of the sample, roughness level, and as a function of nanocoating of the surface in order to modify the wettability. The study classed the sample in three categories, depending on the surface condition: the ultra-smooth surface, the ultra-smooth surface with defect and the rough surface. The good characteristics were obtained for the ultra-smooth sample with randomly distributed defects led to the fabrication of ultra-smooth sample with controlled artificial cavity. The results obtained with these latter samples present the best performances. A two-fold improvement over rough surfaces is observed, representing a substantial gain. Although it is the foundation of most theoretical models, the nucleus at the origin of the formation of a bubble has never been observed experimentally because its size exceeds the capacity of the traditional means of measurement. In this memory, an optical method - based on the resonance of plasmons on surfaces with a diffraction grating - is used to study this phenomenon. The experiments demonstrate the ability of this method to measure the temperature variation in the wall of the sample before boiling. Plasmon resonance measurements show that there is no change in the density of the fluid near the wall for overheating close to the boiling point. The nucleation is too fast to be measured. However, first nuclei of condensation were detected by this method, which is a very promising result.

No presente trabalho realizamos uma análise das lâminas líticas polidas produzidas pelos habitantes pré-históricos no território brasileiro, provenientes de diferentes regiões, grupos e modos de vida. A partir do estudo de coleções arqueológicas e de experimentações pretendemos compreender melhor as diferenças e semelhanças apresentadas por estas lâminas polidas em cada região e sua resistência a testes de impacto em laboratório. Foram analisados 926 artefatos, entre lâminas, fragmentos e alguns percutores. São peças que integram coleções de museus centrais em diferentes regiões do Brasil (Norte, Nordeste, Sudeste e Sul). São principalmente coleções antigas, que apresentam objetos provenientes de diversas partes de cada um dos estados, possibilitando uma cobertura territorial ampla. A despeito dos parcos dados de procedência das peças foi possível caracterizálas regionalmente de forma bastante clara, demonstrando que morfológica e tecnologicamente há variações significativas de uma região para a outra. Em alguns casos foi possível ir ainda mais longe, permitindo propor atribuições culturais a determinados tipos, relacionando-os a algumas Tradições Arqueológicas. No entanto, se tornou evidente também que a partilha dos modos de fazer regionais tem importância capital, que quase sempre vai além das escolhas culturais de um grupo específico. Os trabalhos experimentais (de compressão e impacto) evidenciaram a força necessária para a fragmentação de uma lâmina de basalto de tamanho intermediário, durante seu uso no corte, bem como permitiu estimar a força utilizada por um lenhador mediano, possibilitando compreender melhor algumas relações entre força de impacto, quebras e formas de encabamentos. Finalmente, conseguimos lançar luz sobre a importância das lâminas, tanto para as sociedades do passado, quanto para os arqueólogos do presente, mostrando-as como ferramentas importantes para a compreensão dos modos de vida e dos processos de ocupação do território. / In the present work, we performed an analysis of lithic polished blades produced by the prehistoric inhabitants of the Brazilian territory, from different regions, groups and ways of life. From the study of archaeological assemblages and of experimental archaeology we aim to better understand the differences and similarities presented by these polished blades in each region and their resistance to impact tests. We analyzed 926 artifacts, including blades, fragments and some hammerstones. These items integrate collections of central museums in different regions of Brazil (North, Northeast, Southeast and South). The collections were formed mostly from the middle of the XX century on and present objects from different parts of each of the states, making possible a wide territorial coverage. Despite the scarce data provenance for the pieces it was possible to characterize them regionally quite clearly, showing that morphologically and technologically there are significant variations from one region to another. In some cases it was possible to go even further, allowing the proposition of some cultural attributions to certain types of artifacts, relating them to some Archaeological Traditions. However, it also became clear that sharing the ways of doing things has a major role importance, which often goes beyond the cultural choices of a specific group. The experimental work (of compression and impact) revealed the force required to break a basalt blade of average size during its use in chopping, and allowing us to estimate the force used by an average lumberjack, then enabling a better understanding of some relationships between impact force, breakages and forms of hafting. Finally, we shed light on the importance of the blades, both for past societies, as to the present day archaeologists, showing them as important tools for understanding the ways of life and the processes involved in the human occupation of the territory.

No presente trabalho realizamos uma análise das lâminas líticas polidas produzidas pelos habitantes pré-históricos no território brasileiro, provenientes de diferentes regiões, grupos e modos de vida. A partir do estudo de coleções arqueológicas e de experimentações pretendemos compreender melhor as diferenças e semelhanças apresentadas por estas lâminas polidas em cada região e sua resistência a testes de impacto em laboratório. Foram analisados 926 artefatos, entre lâminas, fragmentos e alguns percutores. São peças que integram coleções de museus centrais em diferentes regiões do Brasil (Norte, Nordeste, Sudeste e Sul). São principalmente coleções antigas, que apresentam objetos provenientes de diversas partes de cada um dos estados, possibilitando uma cobertura territorial ampla. A despeito dos parcos dados de procedência das peças foi possível caracterizálas regionalmente de forma bastante clara, demonstrando que morfológica e tecnologicamente há variações significativas de uma região para a outra. Em alguns casos foi possível ir ainda mais longe, permitindo propor atribuições culturais a determinados tipos, relacionando-os a algumas Tradições Arqueológicas. No entanto, se tornou evidente também que a partilha dos modos de fazer regionais tem importância capital, que quase sempre vai além das escolhas culturais de um grupo específico. Os trabalhos experimentais (de compressão e impacto) evidenciaram a força necessária para a fragmentação de uma lâmina de basalto de tamanho intermediário, durante seu uso no corte, bem como permitiu estimar a força utilizada por um lenhador mediano, possibilitando compreender melhor algumas relações entre força de impacto, quebras e formas de encabamentos. Finalmente, conseguimos lançar luz sobre a importância das lâminas, tanto para as sociedades do passado, quanto para os arqueólogos do presente, mostrando-as como ferramentas importantes para a compreensão dos modos de vida e dos processos de ocupação do território. / In the present work, we performed an analysis of lithic polished blades produced by the prehistoric inhabitants of the Brazilian territory, from different regions, groups and ways of life. From the study of archaeological assemblages and of experimental archaeology we aim to better understand the differences and similarities presented by these polished blades in each region and their resistance to impact tests. We analyzed 926 artifacts, including blades, fragments and some hammerstones. These items integrate collections of central museums in different regions of Brazil (North, Northeast, Southeast and South). The collections were formed mostly from the middle of the XX century on and present objects from different parts of each of the states, making possible a wide territorial coverage. Despite the scarce data provenance for the pieces it was possible to characterize them regionally quite clearly, showing that morphologically and technologically there are significant variations from one region to another. In some cases it was possible to go even further, allowing the proposition of some cultural attributions to certain types of artifacts, relating them to some Archaeological Traditions. However, it also became clear that sharing the ways of doing things has a major role importance, which often goes beyond the cultural choices of a specific group. The experimental work (of compression and impact) revealed the force required to break a basalt blade of average size during its use in chopping, and allowing us to estimate the force used by an average lumberjack, then enabling a better understanding of some relationships between impact force, breakages and forms of hafting. Finally, we shed light on the importance of the blades, both for past societies, as to the present day archaeologists, showing them as important tools for understanding the ways of life and the processes involved in the human occupation of the territory.