Direct laser writing of a new type of optical waveguides and components in silver containing glasses

"Thèse en cotutelle, Doctorat en physique; Université Laval, Québec, Canada et Université de Bordeaux, Talence, France"L'inscription laser directe est un domaine de recherche en croissance depuis ces deux dernières décennies, fournissant un moyen efficace et robuste pour inscrire directement des structures en trois dimensions (3D) dans des matériaux transparents tels que des verres en utilisant des impulsions laser femtosecondes. Cette technique présente de nombreux avantages par rapport à la technique de lithographie, qui se limite à la structuration en deux dimensions (2D) et implique de nombreuses étapes de fabrication. Cela rend la technique d’inscription laser directe bien adaptée aux nouveaux procédés de fabrication. Généralement, l’inscription laser dans les verres induit des changements physiques tels qu'un changement permanent de l'indice de réfraction localisé. Ces modifications ont été classées en trois types distincts:(type I, type II et type III). Dans ce travail, nous présentons un nouveau type de changement d'indice de réfraction, appelé type A qui est basé sur la création d’agrégats d'argent photo-induits. En effet, dans des verres dans lesquels sont incorporés des ions argent Ag+, lors de leur synthèse, l’inscription laser directe induit la création d’agrégats d’argent fluorescents Agmx+ au voisinage du voxel d’interaction. Ces agrégats modifient localement les propriétés optiques comme la fluorescence, la non-linéarité et la réponse plasmonique du verre. Ainsi, différents guides d'ondes, un séparateur de faisceau 50-50, ainsi que des coupleurs optiques ont été inscrits en se basant sur ce nouveau type A et complétement caractérisés. D'autre part, une étude comparative entre les deux types de guides d'ondes (type A et type I) est présentée, tout en montrant qu’en ajustant les paramètres laser, il est possible de déclencher soit le type I soit le type A. Enfin, en se basant sur des guides d’ondes de type A inscrits proche de la surface du verre, un capteur d'indice de réfraction hautement sensible a été inscrit dans une lame de verre de 1 cm de long. Ce capteur miniaturisé peut présenter deux fenêtres de détection d’indice, ce qui constitue une première mondiale. Les propriétés des guides d'ondes inscrits dans ces verres massifs ont été transposées à des fibres en forme de ruban, du même matériau contenant de l'argent. Les résultats obtenus dans ce travail de thèse ouvrent la voie à la fabrication de circuits intégrés en 3D et de capteurs à fibre basés sur des propriétés optiques originales inaccessibles avec des guides d’onde de type I standard.Direct Laser Writing (DLW) has been an exponentially growing research field during the last two decades, by providing an efficient and robust way to directly fabricate three dimensional (3D) structures in transparent materials such as glasses using femtosecond laser pulses. It exhibits many advantages over the lithography technique, which is mostly limited to two dimensional (2D) structuring and involves many fabrication steps. This competitive aspect makes the DLW technique suitable for future technological transfer to advanced industrial manufacturing. Generally, DLW in glasses induces physical changes such as permanent local refractive index modifications that have been classified under three distinct types: (Type I, Type II & Type III). In silver containing glasses with embedded silver ions Ag+, DLW induces the creation of fluorescent silver clusters Agmx+ at the vicinity of the interaction voxel. In this work, we present a new type of refractive index change, called type A occurring in the low pulse energy regime that is based on the creation of the photo-induced silver clusters allowing the creation of new linear and nonlinear optical waveguides in silver containing glasses. Various waveguides, a 50- 50 Y beam splitter, as well as optical couplers, were written based on type A modification inside bulk glasses and further characterized. In addition, a comparitive study between type A and type I waveguides is presented, showing that finely tuning the laser parameters allows the creation of either type A or type I modifications inside silver containing glasses. Finally, based on type A near-surface waveguides, a highly sensitive refractive index sensor is created in a 1 cm glass chip, which could exhibit a pioneer demonstration of double sensing refractive ranges. The waveguiding properties observed and reported in the bulk of such silver containing glasses were transposed to ribbon shaped fibers of the same material. Those results pave the way towards the fabrication of 3D integrated circuits and fiber sensors with original fluorescent, nonlinear and plasmonic properties that are not accessible using the standard type I modification

Bioremediation of petroleum hydrocarbons in coastal sediments

The biodegradation of dispersed crude oil in the ocean is relatively rapid (a half-life of a few weeks). However, it is often much slower on shorelines, usually attributed to low moisture content, nutrient limitation, and higher oil concentrations in beaches than in dispersed plumes. Another factor may be the increased salinity of the upper intertidal and supratidal zones since these parts of the beach are potentially subject to prolonged evaporation and only intermittent inundation. Therefore, two laboratory experiments are conducted to investigate whether such an increase in porewater salinity results in additional inhibitory effects on oil biodegradation in seashores. In the first experiment, oil biodegradation is investigated in seawater at different salinities by evaporating sampled seawater to a concentrated brine and then adding it to fresh seawater to generate high salinity microcosms. Artificially weathered Hibernia crude oil is added, and biodegradation is followed for 76 days. Results show that the biodegradation of hydrocarbons is substantially inhibited at high salinities, whereby the half-life slows down by 20-fold when increasing the salinity from 30 to 160 g/L. Genera of well-known aerobic hydrocarbonoclastic bacteria are only identified at 30 g/L salt in the presence of oil, and only a few halophilic hydrocarbon-degrading microorganisms show a slight enrichment at higher salt concentrations. In the second experiment, oil biodegradation is investigated in coastal sediments. Lightly weathered Hibernia crude oil is added to beach sand at 1 or 10 mL/kg, and fresh seawater, at salinities of 30, 90, and 160 g/L, is added to 20% saturation. The sand mixtures are placed in glass cylinders, with and without the addition of nutrients. All microcosms are analyzed every 30 days for a total incubation period of 180 days. Results show that the biodegradation of oil is slower at higher salinities, where the half-life increases from 40 days at 30 g/L salt to 58 and 76 days at 90 and 160 g/L salt, respectively, and adding fertilizers somewhat enhances oil biodegradation. Increasing oil concentration in the sand, from 1 to 10 mL/kg, slows the half-life by about 10-fold. Interestingly, the biodegradation of aromatic hydrocarbons is much slower at higher salinities, while that of alkanes is not considerably affected. The relative abundance and diversity of genera vary significantly with the increase in porewater salinity, whereby halophilic hydrocarbon-degrading microorganisms, particularly the ones of the Marinobacter genus, are the most abundant only under hypersaline conditions. Enzymes pertaining to hydrocarbon biodegradation pathways are noticeably less abundant at high salinities, specifically for those pertaining to the degradation pathways of aromatics. Both experiments indicated that high porewater salinity in the upper parts of sandy beaches could significantly slow down the microbial degradation of crude oil, specifically that of the aromatic fraction. Consequently, occasional irrigation with seawater (i.e., to decrease the salinity) with fertilization could be a suitable bioremediation strategy for the upper parts of contaminated beaches. However, given that the high oil concentration in sandy beaches also plays a major role in the persistence of petroleum hydrocarbons on contaminated shorelines, chemically dispersing the spilled oil at sea and preventing it from reaching the coast is probably the most suitable option for its optimal removal from marine and coastal ecosystems

Event Driven Tactile Sensors for Artificial Devices

Present-day robots are, to some extent, able to deal with high complexity and variability of the real-world environment. Their cognitive capabilities can be further enhanced, if they physically interact and explore the real-world objects. For this, the need for efficient tactile sensors is growing day after day in such a way are becoming more and more part of daily life devices especially in robotic applications for manipulation and safe interaction with the environment. In this thesis, we highlight the importance of touch sensing in humans and robots. Inspired by the biological systems, in the the first part, we merge between neuromorphic engineering and CMOS technology where the former is a eld of science that replicates what is biologically (neurons of the nervous system) inside humans into the circuit level. We explain the operation and then characterize different sensor circuits through simulation and experiment to propose finally new prototypes based on the achieved results. In the second part, we present a machine learning technique for detecting the direction and orientation of a sliding tip over a complete skin patch of the iCub robot. Through learning and online testing, the algorithm classies different trajectories across the skin patch. Through this part, we show the results of the considered algorithm with a future perspective to extend the work

Birkhoff normal form in low regularity for the nonlinear quantum harmonic oscillator

Given small initial solutions of the nonlinear quantum harmonic oscillator on $\mathbb{R}$, we are interested in their long time behavior in the energy space which is an adapted Sobolev space. We perturbate the linear part by $V$ taken as multiplicative potentials, in a way that the linear frequencies satisfy a non-resonance condition. More precisely, we prove that for almost all potentials $V$, the low modes of the solution are almost preserved for very long times

Levetiracetam in the treatment of epilepsy

Epilepsy is a common chronic disorder that requires long-term antiepileptic drug therapy. Approximately one half of patients fail the initial antiepileptic drug and about 35% are refractory to medical therapy, highlighting the continued need for more effective and better tolerated drugs. Levetiracetam is an antiepileptic drug marketed since 2000. Its novel mechanism of action is modulation of synaptic neurotransmitter release through binding to the synaptic vesicle protein SV2A in the brain. Its pharmacokinetic advantages include rapid and almost complete absorption, minimal insignificant binding to plasma protein, absence of enzyme induction, absence of interactions with other drugs, and partial metabolism outside the liver. The availability of an intravenous preparation is yet another advantage. It has been demonstrated effective as adjunctive therapy for refractory partial-onset seizures, primary generalized tonic-clonic seizures, and myoclonic seizures of juvenile myoclonic epilepsy. In addition, it was found equivalent to controlled release carbamazepine as first-line therapy for partial-onset seizures, both in efficacy and tolerability. Its main adverse effects in randomized adjunctive trials in adults have been somnolence, asthenia, infection, and dizziness. In children, the behavioral adverse effects of hostility and nervousness were also noted. Levetiracetam is an important addition to the treatment of epilepsy

Cold dark matter in brane cosmology scenario

We analyze the dark matter problem in the context of brane cosmology. We investigate the impact of the non-conventional brane cosmology on the relic abundance of non-relativistic stable particles in high and low reheating scenarios. We show that in case of high reheating temperature, the brane cosmology may enhance the dark matter relic density by many order of magnitudes and a stringent lower bound on the five dimensional scale is obtained. We also consider low reheating temperature scenarios with chemical equilibrium and non-equilibrium. We emphasize that in non-equilibrium case, the resulting relic density is very small. While with equilibrium, it is increased by a factor of O(10^2) with respect to the standard thermal production. Therefore, dark matter particles with large cross section, which is favored by detection expirements, can be consistent with the recent relic density observational limits.Comment: 14 pages, 1 figur

A New Treatment for Aphasia? Borrowing from the Field of Foreign Language Learning

This is a report of a new type of aphasia treatment using a single subject design. The treatment was based on the principles of TPR (Total Physical Response), an innovative method for teaching language, whose main principle is that language is best learned when paired with movement and gesture. The underlying principle of TPR for aphasia treatment lies in the recruitment of the right hemisphere to help in language reorganization. We present a subject with severe fluent aphasia, 2 years post-stroke with no prior treatment, and report on his progress during TPR-based therapy

Characteristics of polyps in Lebanese population

Background: The objective of this study is to describe characteristics of the polyps in Lebanese population and evaluate the dysplasia and its relation to the polyps’ locations. Methods: Retrospective descriptive study was conducted at the Department of National Institute of Pathology in Lebanon and comprised biopsy of colonic polyps or resected polyps from patients from 2007 to 2009. We collected demographic data and polyps’ characteristics. Then, we divided patients according to age sex, location, histology. Results: With 2298 polyps in 1470 patients, the mean age was 57.45 with 68% aged more than 50yo. 75.6% have one polyps and multiple polyps more commonly found in older patient (> 50 years). More than 20 % of polyps found in the recto-sigmoid area. In the right colon, people older than 50 years were more likely to have polyps (19%) compared to those < 30 years (8.3%) (p < 0.05). In the rectum, people < 30 years were more likely to have polyps compared to those > 50 years (p < 0.01). Concerning the histology, tubular adenoma is the most common type and more prevalent in left colon. Hyperplastic polyps mainly found in the recto-sigmoid area and mainly in age group 30-50 in contrast to adenomatous polyps found over 50yo. Adenocarcinomas and/or degenerative polyps were founded in 5.9% of our population. Conclusion: This study gives valuable information on colorectal polyp in Lebanese population about age, sex, dominant histology and anatomic location. We noted a male predominance and mainly above 50 years old. The majority had single polyps, >50% of polyps were localized in the recto sigmoid. Adenomatous polyps were the most common type

L’ART POST-CATASTROPHE : UN TÉMOIN ACTIVISTE

Le Liban, un pays riche artistiquement et intellectuellement, est la scène par excellence d’un enchainement de catastrophes depuis sa naissance jusqu’à nos jours. L’explosion du port de Beyrouth le 4 Août 2020 en constitue l’ultime épisode et peut-être le plus dramatique de tous. Un phénomène inédit s’est révélé suite à cette tragédie sans précédent : la scène culturelle s’est immédiatement mobilisée sans passer par une étape mnésique post catastrophe comme c’est en général le cas après un désastre. Que s’est-il passé ? Pourquoi une telle urgence ? Comment les artistes ont-ils utilisé leur créativité pour exprimer l’indicible, le penser, en témoigner, sensibiliser et commencer un processus de guérison des blessures traumatiques ? Afin de répondre à cette problématique, nous allons explorer une création post-catastrophe relevant des arts visuels. L’exposition L\u27Art Blessé présentée du 16 décembre 2020 au 16 janvier 2021 à La Villa Audi, propose une série d’oeuvres sinistrées provenant de collections privées beyrouthines. Les dommages subis vont engendrer une mise en abyme où les traces se métamorphosent en oeuvre dans l’oeuvre. La scénographie de l’architecte Jean Louis Mainguy, accompagnée de poèmes et de musique, est ancrée dans l’interdisciplinarité