Dissertations / Theses on the topic 'Microanalyis'

Cette thèse a pour objet l’œuvre du poète britannique Ted Hughes et se concentre sur la question de l’accomplissement de l’être et du langage. Le poète décrit le parcours de l’homme du « logos », héritier de Socrate et de Descartes, criminel châtié pour avoir voulu, par la seule force de son esprit, se faire maître et possesseur de son corps et de la nature tout entière. La mythologie personnelle que Ted Hughes développe dans son œuvre poétique et critique lui permet d’y tracer l’infini cheminement du sujet humain qui, reconnaissant ses torts envers la Déesse de l'Être Complet, sa Terre-Mère et sa Fiancée Sacrée, à la fois Reine des Enfers et Fleur du Paradis, renonce à tout et accepte de s’offrir en un don absolu. C’est par cette métamorphose qu’a lieu l’ultime et inespéré « miracle poétique » qui révèle le noyau vital, divin et insondable de l’être poétique. Il faut, selon le poète, parler comme les animaux et les oiseaux, qui, bien au-delà des mots des hommes, parviennent à faire valoir la vérité de l’existence dans ce qu’elle a de plus « étrange, beau, pathétique et terrible ». Il faut comprendre la musique silencieuse du vent, de l’herbe et des pierres : ils portent la vérité ineffable d’une Déesse sans nom, « Annonciation de glaise, d’eau et de soleil » ou « crocus évangile » qui impose à l’homme de tout risquer et de s’offrir sans réserve. C’est le don du funambule errant qui danse sur un fil infini comme s’il était déjà mort : il connaît la douceur de l’agonie et la douleur de l’extase, il en a fait sa plaie noire et son joyau arc-en-ciel, magie de poésie qui fonde le cœur insondable de l’être et du langage
This thesis explores Ted Hughes’s poetic work and focuses on the question of the completion of being and of language. The poet sheds light on the man of ‘logos’, heir to Socrates and Descartes, criminal because he wanted, by the sole force of his rational mind, to own and control the outer world of nature and to be the master of the inner world of his individuality, body and soul alike. The myths and stories that fill Ted Hughes’s poetic and critical work trace the trajectory of a human being who has acknowledged the harm he has done and asks for forgiveness to the Goddess of Complete Being, both his Mother-Earth and Sacred Bride, both Queen of Hell and Flower of Paradise. As he surrenders to her unconditionally, an ultimate and ‘last-ditch miracle’ occurs, one that reveals his true and divine ‘self at the source’, his ‘vital nucleus’ and ‘the most inaccessible thing of all’. According to the poet, one should speak like the animals and the birds that, far beyond human words, manage to ‘express this being pure and without effort’ and a truth ‘at the core of us – strange, beautiful, pathetic, terrible’. One should decipher the inaudible music of the wind, the grass and the rocks, because it bears the truth of a nameless Goddess, the ‘Annunciation of clay, water and sunlight’, or the ‘crocus evangels’, which tell man that he should take all the risks throughout his journey. The human being that the poet describes has a black wound on his body and a rainbow jewel in his soul; he has been through the softness of agony and the sorrows of ecstasy – and thus he feels the inmost core of being and of language, and the secret of the magic spell cast by poetry

The discrimination and/or matching of dye extracts is an important aspect of forensic investigations involving textile samples. The aim of this work was to study the use of Fourier transform infrared spectrometry and diffuse reflectance to obtain IR spectra of dye samples, and the subsequent analysis of these spectra using library searching and principle component analysis. The work in this thesis has demonstrated the development of a simple method for obtaining DRIFT spectra of dye samples. Library searching and principle component analysis were used to distinguish between many types of dye samples, including extracts that were not distinguished using TLC.

Low doses of dopamine autoreceptor (DA) agonists are presumed to act by stimulating DA autoreceptors on the sona/dendrites and axon terminals of DA neurons. Low doses of apomorphine reduced food Intake, in a microstructural analysis paradigm, by reducing both the time spent feeding and the rate of food ingestion. The reduction of eating time was shown to result from the stimulation of DA autoreceptors located on the cell bodies and dendrites of the mesolimbic DA system. The reduction of eating rate however, appeared to result from the activation of axon terminal DA autoreceptors. The significance of this dissociation is discussed in relation to the mechanisms through which presynaptic DA receptors on the same neuron may subserve different behavioural functions. The observation that apomorphine administration resulted in a selective manipulation of the microstructural parameters of feeding, was then used to assess the action of antidepressant drugs on DA autoreceptor function. In both normal and chronically stressed rats, chronic antidepressant treatment failed to alter the sensitivity of DA autoreceptors. However, on withdrawal, the sensitivity of cell body DA autoreceptors appeared reduced, as apomorphine no longer in any way influenced the time spent feeding in the microstructural paradigm. The Implications of these findings are discussed in relation to the hypothesis that antidepressant drugs increase DA function by reducing the sensitivity of presynaptic DA receptors.

L'analyse par microsonde électronique (EPMA) permet de quantifier, avec une grande précision, les concentrations élémentaires d'échantillons de compositions inconnues. Elle permet, par exemple, de quantifier les actinides présents dans les combustibles nucléaires neufs ou irradiés, d'aider à la gestion des déchets nucléaires ou encore de dater certaines roches. Malheureusement, ces analyses quantitatives ne sont pas toujours réalisables dû à l'indisponibilité des étalons de référence pour certains actinides. Afin de pallier cette difficulté, une méthode d'analyse dite « sans standard » peut-être employée au moyen d'étalons virtuels. Ces derniers sont obtenus à partir de formules empiriques ou à partir de calculs basés sur des modèles théoriques. Toutefois, ces calculs requièrent la connaissance de paramètres physiques généralement mal connus, comme c'est le cas pour les sections efficaces de production de rayons X. La connaissance précise de ces sections efficaces est requise dans de nombreuses applications telles que dans les codes de transport de particules et dans les simulations Monte-Carlo. Ces codes de calculs sont très utilisés en médecine et particulièrement en imagerie médicale et dans les traitements par faisceau d'électrons. Dans le domaine de l'astronomie, ces données sont utilisées pour effectuer des simulations servant à prédire les compositions des étoiles et des nuages galactiques ainsi que la formation des systèmes planétaires.Au cours de ce travail, les sections efficaces de production des raies L et M du plomb, du thorium et de l'uranium ont été mesurées par impact d'électrons sur des cibles minces autosupportées d'épaisseur variant de 0,2 à 8 nm. Les résultats expérimentaux ont été comparés avec les prédictions théoriques de sections efficaces d'ionisation calculées grâce à l'approximation de Born en ondes distordues (DWBA) et avec les prédictions de formules analytiques utilisées dans les applications pratiques. Les sections efficaces d'ionisation ont été converties en sections efficaces de productions de rayons X grâce aux paramètres de relaxation atomique extraits de la littérature. Les résultats théoriques du modèle DWBA sont en excellents accords avec les résultats expérimentaux. Ceci permet de confirmer les prédictions de ce modèle et de valider son utilisation pour le calcul de standards virtuels.Les prédictions de ce modèle ont été intégrées dans le code Monte-Carlo PENELOPE afin de calculer l'intensité de rayons X produite par des standards pur d'actinides. Les calculs ont été réalisés pour les éléments dont le numéro atomique est 89 ≤ Z ≤ 99 et pour des tensions d'accélération variant du seuil d'ionisation jusque 40 kV, par pas de 0,5 kV. Pour une utilisation pratique, les intensités calculées pour les raies L et M les plus intenses ont été regroupées dans une base de données.Les prédictions des standards virtuels ainsi obtenus ont été comparées avec des mesures effectuées sur des échantillons de composition connue (U, UO2, ThO2, ThF4, PuO2…) et avec les données acquises lors de précédentes campagnes de mesures. Le dosage des actinides à l'aide de ces standards virtuels a montré un bon accord avec les résultats attendus. Ceci confirme la fiabilité des standards virtuels développés et démontre que la quantification des actinides par microsonde électronique est réalisable sans standards d'actinides et avec un bon niveau de confiance
Electron probe microanalysis (EPMA) is used to quantify with a high accuracy the amount of different elements present on a sample of unknown composition. EPMA is largely used to quantify the amount of actinides present in fresh and irradiated fuels, to manage waste disposal and to date rocks. However, quantitative EPMA is not always possible to achieve for these materials due to the lack of suitable reference standards for the radionuclides. To overcome this difficulty, standardless methods of analysis are employed with mean of virtual calculated standards. These calculated standards are generally obtained from empirical formulae based on experimental extrapolations or from theoretical calculations that require physical parameters which are poorly known as it is the case for the X-ray production cross section.The accurate knowledge of these cross sections is required in many applications such as in particle transport code and in Monte Carlo simulations. The computer simulations are widely used in the medical field and particularly in medical imaging and in electron beam therapy. In the field of astronomy, these data are used to perform simulations that predict the compositions of stars and galactic clouds, and the formation of planetary systems.In the present work, L- and M-shell absolute x-ray production cross sections were determined experimentally for elements lead, thorium and uranium by electron impact using ultrathin self-supporting targets with thickness varying from 0.2 to 8 nm. The measured cross sections have been compared, with the distorted-wave Born approximation (DWBA) calculated by Bote et al. and with the predictions of analytical formulae widely used in practical applications. For the conversion of inner-shell ionization cross sections into x-ray production cross sections, atomic relaxation parameters were extracted from the literature. The predictions of the DWBA calculations are in excellent agreement with our measured x-ray production cross sections. This confirms the predictive results of this model and its usefulness for the calculation of virtual standards.The DWBA calculations were used into the Monte Carlo simulation code PENELOPE to calculate the X-ray intensity produced by pure actinide standards. The X-ray intensities were calculated for elements with atomic number 89 ≤ Z ≤ 99 and for accelerating voltage ranging from the ionization threshold up to 40 kV with a step of 0.5 kV. For a practical use, the calculated intensities for the most intense L and M lines were stored in a database.The predictions of our calculated standards have been compared with the x-ray intensity of known composition actinide samples (such as U, UO2, ThO2, ThF4, PuO2…) and with the data acquired during previous measurement projects. Actinide quantifications performed by virtual standards were found to be in fair agreement with the expected results. This confirms the reliability of the developed virtual standards and demonstrates that actinide quantification by EPMA can now be possible to perform without material actinide standards and with a good level of accuracy

Nombreuses prévues et études sur la transmission inter et trans-générationnelle du traumatisme nous confirment l'évidence de la transmission sans pour autant en donner une description détaillé du processus qui pourrait être à la base de la transmission directe de la mère au bébé. La compréhension de ce processus pourrait permettre de penser et promouvoir des dispositifs de soin précoce pour les mères traumatisées et leurs bébés. Cela s'avère d'autant plus important dans les contextes de trauma collectif, comme les situations d'urgence humanitaire, où une large partie de la population est exposée à des événements traumatiques extrêmes et répétés. Dans le but d’identifier les déterminantes propres à la transmissions directe du traumatise psychique de la mère au bébé en contexte humanitaire, nous avons recrutées vingt-quatre dyades mère-bébé, en trois pays affectés par la crise politico-religieuse centrafricaine démarrée en 2013 (République Centrafricaine, Tchad et Cameroun). Dans les vingt-quatre dyades, les mères ont été exposées à un ou plusieurs événements traumatiques, en l'absence du bébé, avant sa naissance ou pendant la grossesse ; l'âge de bébé est compris entre un mois et trois ans. Ces Mères et bébés ont étés rencontré lors d'un entretien semi structuré que nous avons filmé. Cela pour permettre une microanalyse des interactions trans-modales (visuelles, corporelles, vocales) entre mère et bébé, dans l'idée de comprendre si pendant la révocation de l'événement traumatique de la part de la mère, les interactions subissaient des modifications et dans ce cas, lesquels. Les interactions dyadiques ont été aussi observées dans une situation de jeu libre sans la présence d'interviewer. Les représentations maternelles ainsi que les marqueurs traumatiques dans le discours ont été pris en compte comme facteurs contributeurs de la transmission traumatique. Les résultats de l'analyse des échanges dyadiques pendant l'entretien, montrent une évidence dans le changement d'interactions dans le moment de révocation traumatique de la mère. Les détails de cette différence d'interaction entre mère et bébé sont présentés dans la session de résultats. Dans la discussion ils sont ensuite mis en relation avec le discours de la mère où nous pouvons remarquer le rôle de représentations maternelle à propos du bébé qui ont une implication importante dans la transmission traumatique. L'analyse de toutes ces composantes multiples semble nous indiquer que le traumatisme maternelle influence les représentations de la mère à propos du bébé, de sa relation avec lui et du mandat transgénérationnelle dont le bébé va être investi. De plus les mères traumatisées, envahies par leur propre état émotionnel négatif ont des difficultés à interpréter correctement les expressions verbales et non verbales du bébé et à trouver des réponses appropriées. Cette difficulté se traduit dans la transmission de son état émotionnel négatif au bébé, qui interprète l'absence de réponse de la mère ou les réponses pas adéquates à ses sollicitations, comme des signaux négatifs vis-à-vis de son propre état émotionnel. Lé bébé et il n'a pas d' autres stratégies que celle d'internaliser l'état affectif négatif maternel et de le transformer dans son propre état interne. Malgré l'évidence de la transmission de l état émotionnel négatif de la mère au bébé, nous avons pu observer certains facteurs de protection qui peuvent préserver les mères et les bébés de l'inévitabilité de cette transmission. Les mères et les bébés montrent plusieurs ressources et compétences internes qui nous laissent penser qu'une réparation est possible ainsi qu'une prévention de la transmission traumatique quand le processus est déjà démarré. Pour conclure ce travail nous présentons de propositions cliniques de prise en charge des mère ayant vécu un traumatisme et leur bébé, dans le but de réduire les effets de la possible transmission du traumatisme au bébé ou, quand possible, de la prévenir
Several studies on the inter- and trans-gerational transmission of trauma confirm the evidence of transmission without giving a detailed description of the process that could be the basis of mother to child direct transmission. Understanding this process could help to think and promote early care for traumatized mothers and their children. This is especially important in contexts of collective trauma, such as humanitarian emergencies, where a large part of the population is exposed to extreme and repeated traumatic events. In order to identify the determinants of the mother to child direct transmission in a humanitarian context, we recruited twenty-four mother-child dyads, in three countries affected by the Central African political and religious crisis started in 2013 (Central African Republic, Chad and Cameroon). The twenty-four dyads were composed by mothers exposed to one or more traumatic events, in the absence of the child, before childbirth or during pregnancy and their children, aged from one month to three years. We met the mother-child dyads during a semi-structured interview that we filmed in order to allow a microanalysis of the cross-modal (visual, bodily, vocal) interactions between mother and child. The objective was to understand whether interactions underwent modifications during the revocation of the traumatic event by the mother, and if yes, to have a better comprehension of these changes. Dyadic interactions were also observed in a free play situation without the presence of interviewers. Maternal representations as well as traumatic markers in mother discourse have been taken into account as factors contributing to the traumatic transmission. The results of the dyadic exchanges analysis during the interview show some evidences in the modification of interactions during the traumatic revocation of the mother. The details of this difference in mother-child interactions are presented in the results session. In the discussion session, the results from the microanalysis of interactions, have been connected to the mother's speech where we can notice the role of maternal representations about the child that have an important involvement in traumatic transmission. The analysis of all these multiple components seems to indicate that maternal trauma influences the mother's representations about the child, her relationship with him and the intergenerational mandate of which the child will be assigned to. In addition, traumatized mothers who are overwhelmed by their own negative emotional state, have difficulties in interpreting the child's verbal and non-verbal expressions correctly and finding appropriate answers. This difficulty is reflected in the transmission of mother negative emotional state to the child, who interprets the mother's lack of response or inadequate responses to his solicitations, as negative signals about his own emotional state. The child has no other strategies than internalizing the maternal negative affective state and transforming it into its own internal state. Despite the evidence of the transmission of the negative emotional state from the mother to the child, we have observed some protective factors that can preserve mothers and children from the inevitability of this transmission. Mothers and children show many internal resources and skills that suggest a possible recovery as well as give the basis to think about the prevention of traumatic transmission, when the process is already underway. To conclude this work we present clinical applications for the management of traumatized mothers and their young children in order to reduce the effects of the possible transmission of trauma to the child or, where possible, to prevent it
Diversi studi sulla trasmissione inter e tran-generazionale del trauma confermano l'evidenza della trasmissione, ma senza fornire una descrizione dettagliata del processo che potrebbe essere alla base della trasmissione diretta dalla madre al bambino. Comprendere questo processo potrebbe aiutare a pensare e promuovere la cura precoce delle madri traumatizzate e dei loro bambini. Ciò è tanto più importante nelle situazioni di trauma collettivo, come possono essere le emergenze umanitarie, dove una gran parte della popolazione è esposta a eventi traumatici estremi e ripetuti. Al fine di individuare le caratteristiche specifiche della trasmissione diretta del trauma psichico dalla madre al bambino in ambito umanitario, abbiamo reclutato ventiquattro diadi madre-bambino in tre paesi colpiti dalla crisi politico-religiosa della Repubblilca Centrafricana che ha avuto inizio nel 2013 (Centrafrica, Ciad e Camerun). Nelle ventiquattro diadi, la madre ha assistito a uno o più eventi traumatici in assenza del bambino, prima della nascita o durante la gravidanza e il bambino ha un'età compresa tra un mese e tre anni. Hanno partecipato a un' intervista semi-strutturata che abbiamo filmato per consentire la microanalisi delle interazioni cross-modali (visive, corporee, vocali) tra madre e bambino, con l'obiettivo di comprendere se durante la rievocazione dell'evento traumatico della madre, le interazioni madre-bambino si modificano e in questo caso, come. Le interazioni diadiche sono state osservate anche in una situazione di gioco libero senza la presenza d¿intervistatori. Le rappresentazioni materne e gli elementi identificatori del trauma nel discorso della madre sono stati considerati come fattori che contribuiscono alla trasmissione traumatica. I risultati delle analisi dell'interazione diadica durante l'intervista mostrano un cambiamento evidente dell'interazione nel momento della narrazione traumatica della madre. I dettagli delle differenze osservate nell'interazione madre-bambino sono presentati nella sessione dei risultati e nella discussione sono messi in relazione con il contenuto e la forma del discorso della madre, in cui è possibile vedere il ruolo delle rappresentazioni materne à proposito del bambino, nella trasmissione del trauma. L'analisi di tutti queste componenti multiple suggerisce che il trauma materno ha un impatto sulle rappresentazioni della madre a proposito del suo bambino, del rapporto che ha con lui e del mandato transgenerazionale di cui il bambino sarà portatore. Inoltre, le madri traumatizzate, invase dal proprio stato emotivo negativo, mostrano una difficoltà a interpretare correttamente le espressioni verbali e non verbali del bambino e a trovare delle risposte adeguate alle sue sollicitazioni. Questa difficoltà si traduce nella trasmissione dello stato emotivo negativo della madre al bambino, che interpreta la mancanza di risposta della madre o le risposte inadeguate alle sue richieste, come segnali negativi rispetto al suo stato emotivo. Il bambino non riesce a trovare altre strategie oltre a quella di interiorizzare lo stato emotivo negativo della madre e trasformarlo nel proprio stato emotivo interno. Nonostante le prove della trasmissione dello stato emotivo negativo dalla madre al bambino, abbiamo osservato alcuni fattori protettivi in grado di preservare le madri e i bambini dall'inevitabilità della trasmissione. Madri e bambini mostrano diverse risorse e competenze interne che ci portano a immaginare che una "riparazione" è possibile, cosi come anche la prevenzione della trasmissione traumatica, nel caso in cui il processo è già avviato. Per concludere questo lavoro, presentiamo delle proposte cliniche destinate alle madri traumatizzate e ai loro bambini, al fine di ridurre gli effetti della possibile trasmissione del trauma al bambino o, quando possibile, per impedirla

Carbon nanotubes (CNTs) are a highly promising material for future interconnects. It is expected that the decoration of CNTs with Cu particles or also the filling of the interspaces between the CNTs with Cu instead of the currently used SiO2 can enhance the performance of CNT-based interconnects. Due to the high aspect ratio of CNTs an appropriate deposition technique has to be applied which is able to coat such structures uniformly. The current work is therefore considered with thermal atomic layer deposition (ALD) of CuxO from the liquid Cu (I) β-diketonate precursor [(nBu3P)2Cu(acac)] and wet oxygen at 135°C on variously pretreated multi-walled CNTs. The different in-situ pre-treatments of the CNTs with oxygen, water vapor and wet oxygen in a temperature range from 100 to 300°C at a pressure of 1.33 mbar have been carried out prior to the ALD to enable uniform nucleation on the otherwise chemical inert CNT surface. The reduction of the CuxO as well as the filling of the space between the CNTs is not part of this work. Variations of the oxidation temperature as well as the oxidation agents resulted in different growth modes of the CuxO. An oxidation with wet oxygen at 300°C yielded in a partially layer like growth of the CuxO. It is expected that this growth mode is connected to a partial destruction of the outer CNT shell due to the oxidation. However, the damage introduced to the CNTs was not high enough to be detected by Raman spectroscopy. For all other investigated pretreatments, the formation of nanoparticles (NPs) was observed by electron microscopy. This formation of CuxO NPs can be explained by the metal-tube-interaction. Furthermore, the NPs probably decorate defect sites of the CNTs due to their higher reactivity. Additionally, analysis of energy-dispersive X-ray spectroscopy and spectroscopic ellipsometry measurements suggests that the used precursor [(nBu3P)2Cu(acac)] requires reactive oxygen surface groups for initiating the ALD growth. The observation of layer-like growth of CuxO on CNTs pretreated with wet oxygen at 300°C appears promising for deposition processes of Cu seed layers on CNTs. However, more aggressive pretreatments at higher temperatures or with more aggressive oxidation agents could be required to enable layer like growth on the entire CNTs.

La grande majorite des materiaux dans l'environnement humain sont des materiaux isolants. Ces materiaux jouent un role tres important dans differents domaines d'etude notamment en geologie et en biologie. Il est bien connu que ces materiaux sont difficiles a caracteriser a l'aide de techniques utilisant des particules chargees (microscopie electronique et techniques associees (epma, cathodoluminescence, etc. )). En effet, sous irradiation electronique, ils developpent une charge d'espace qui perturbe l'observation et l'analyse. Le but de ce travail, est de montrer l'influence de cette charge sur les signaux x emis, que l'echantillon soit recouvert par un film metallique mis a la masse ou non. L'etude des isolants recouverts est abordee theoriquement en utilisant les simulations de monte-carlo. Il s'agit d'inclure dans ces simulations le champ electrique interne resultant de la charge d'espace pour determiner les variations du signal x emis dues soit aux modifications des parametres d'interaction electron-matiere, soit aux modification chimiques (electromigration). Une etude experimentale de ces phenomenes (effets de charge) a ete realisee pour valider ces simulations. Dans cette etude nous avons mesure pour la premiere fois la quantite de charge piegee dans l'isolant recouvert par une methode basee sur le phenomene d'influence. Les isolants nus sont abordes qualitativement. Nous avons mis en evidence a l'aide d'un spectrometre d'electrons de type toroidal, une source d'electrons parasite responsable d'un spectre d'emission x perturbateur qui deforme le spectre initial, empechant toute analyse meme qualitative. D'autre part, nous avons mis en cause les methodes mesurant le potentiel de surface utilisant la limite de duane-hunt.

Le but de cette thèse est de comprendre les changements dans les propriétés électriques et optiques des matériaux à large bande interdite à l'échelle nanométrique par rapport au matériau massif et en présence d'un champ électrique statique intense. Le diamant en forme de nano-aiguille a été choisi comme matériau d'étude en raison de sa large bande interdite, sa haute résistance aux contraintes externes et sa conduction thermique élevée. Le diamant présente également une résistance électrique élevée, ce qui en fait un bon candidat pour l'étude des modifications de conduction électrique sous des champs électriques et optiques forts. Afin d'étudier les propriétés de conduction électrique, deux différentes techniques expérimentales ont été utilisées : la microscopie ionique à effet de champ et la microscopie électronique à effet de champ avec et sans éclairement laser. Les observations expérimentales ont été couplées à des modèles de conduction électrique qui décrivent qualitativement et quantitativement les résultats obtenus. Pour l'étude des propriétés optiques, une microscopie électronique à émission de champ assistée par laser a été réalisée. Dans ce cas, l'étude a été menée dans deux configurations expérimentales : l'une en éclairant l'ensemble de l'échantillon par le faisceau laser et l'autre en focalisant le laser uniquement sur le sommet de la nano-pointe où le champ électrique est augmenté et les électrons sont émis dans le vide. Les résultats décrivent les propriétés de conduction électrique et d'émission d'électrons des nano-aiguilles de diamant dans l'obscurité et sous un éclairement laser. En tant qu'émetteurs d'électrons, les nano-aiguilles de diamant présentent des avantages par rapport aux pointes métalliques telles qu'une stabilité d'émission et un seuil de dommage plus élevés sous éclairement laser. Les résultats sont prometteurs pour le développement d'une nouvelle source de photo- électrons pour la microscopie électronique résolue en temps
The aim of this thesis is to understand the changes in the electrical and optical properties of large band-gap materials at the nanoscale in the presence of a huge static electric _eld. Diamond nano-needle has been chosen as a study material, thanks to its wide band gap, high resistance to external stress and high thermal conduction. Diamond presents also high electrical resistance, making it a good candidate for the study of electrical conduction modi_cations under high electric and optical _elds. In order to study the electrical conduction properties, two di_erent experimental tech- niques were used: Field Ion microscopy and Field Emission Microscopy with and without laser illumination. The experimental observations were coupled with electrical conduction models which describe qualitatively and quantitatively the obtained results. For the study of the optical properties, laser-assisted Field Emission Microscopy was performed. In this case, the study was performed in two experimental con_gurations: one by illuminating the whole sample by the laser beam and the other by focusing the laser beam only on the apex of the nano-tip where the electric _eld is enhanced and the electrons are emitted into vacuum. The results describe the electrical conduction and electron emission properties of the diamond nano-needles in dark and under laser illumination. As _eld emitters, diamond nano-needles show advantages compared to metallic tips such as: higher emission stability and higher damage threshold under laser illumination. The results are promising for the development of novel photo-electron sources for time- resolved electron microscopy

Coatings are often used on critical components in machines and engines to reduce wear and to provide low friction in order to reduce energy losses and the environmental impact. A triboactive coating not only provides this desired performance, it also actively maintains the low friction by a structural or chemical change in a very thin top layer of these already micrometer thin coatings. This so-called tribofilm is often 5-50 nm thick and can be formed either from the coating itself or by a reaction with the counter surface or the surrounding atmosphere, i.e. gas, fuel, oil, etc. The tribofilm will maintain the wanted performance for as long as the system is not chemically disturbed. This thesis provides a detailed overview of the functionality of triboactive low-friction coatings, in many different systems. The majority of the tribofilms discussed, formed in very different environments, are built up by tungsten disulfide (WS2), which is a material similar to graphite, with a lamellar structure where strongly bonded atomic planes may slip over each other almost without resistance. The major difference is that WS2 is an intrinsically triboactive material, while graphite is not. However, graphite and other carbon-based materials can be made triboactive in certain atmospheres or by addition of other elements, such as hydrogen. The remarkable affinity and driving force to form such WS2 low-friction tribofilms, regardless of the initial states of the sulfur and tungsten, and even when the forming elements are present only at ppm levels, is a recurrent observation in the thesis. Addition of an alloying element to sputtered coatings of WS2 can improve its mechanical and frictional properties significantly. Several promising attempts have been made to find good candidates, out of which a few important ones are investigated in this thesis. Their achievable potential in friction reductions is demonstrated. By reducing friction, energy losses can be avoided, which also results in lower particle and exhaust emissions, which directly reduces the environmental impact. Triboactive coatings are shown to be a promising route to significantly improve tribological applications and allow more environmental friendly and energy efficient vehicles.

This thesis set out to identify the various techniques used by stand-up comedians to invite laughter and other affiliative responses from their audiences. A corpus of 13 televised stand-up comedy performances was analysed both qualitatively and quantitatively, and comparative analyses of different audience responses (including laughter and applause) were presented. Coding schemes that had been designed for analysing audience applause during political speeches were found to account for many of the audience responses during stand-up comedy performances, but differences between both performer and audience behaviours in the two genres were also identified. A taxonomy of comedy invitation devices was proposed, containing 16 different verbal and non-verbal invitational techniques that were observed in the corpus. In a quantitative comparison of two ofthese, no statistical difference was found between the invitational use of gestures and standard rhetorical devices, although both techniques were used during all of the performances in the corpus. An analysis ofpotential forms of disaffiliation suggested that non-responses were more disaffiliative than either uninvited responses or invited responses ofweak affiliation intensity. Finally, a number of ways of identifying skill as a stand-up comedian were proposed, including the use of subtle invitational cues, combining several comedy invitation devices at salient response invitation points, and moving on swiftly and fluently when laughter invitations are not taken up by the audience.

The main objective of this project was to master the electron probe x-ray microanalysis technique to permit one to obtain physiologically meaningful quantitative elemental profiles (Na, Cl, K, P, Mg, Ca & S) for the components of a given cell. The techniques which had to be mastered were: preparation of mammalian (rat) cardiac muscle; 'rapid' cryofixation using a Reichert-Jung MM80E 'impact freezer'; cryosectioning using a Reichert-Jung FC4 cryoultramicrotome; transfer and freeze-drying; electron probe x-rays collection using the EDAX 9100 Series Energy Dispersive X-ray Analysis Systems attached to a Philips TEM 420; quantitative analysis using the Hall equation and thin membrane aminoplastic standards. Different methods of transfer and freeze-drying were compared. Method I-a. Cryotransfer to the electron microscope using a modified Philips Cryotransfer system, freeze-drying in the column of the electron microscope, x-rays collection at low temperature; Method I-b. Cryotransfer to the electron microscope using a modified Philips Cryotransfer system, freeze-drying in the column of the electron microscope, x-rays collection at ambient temperature; Method II. Cryotransfer to a vacuum chamber (Edward-Coating System E306 A) using a precooled metal carrier, freeze-drying in a vacuum chamber while warming at ambient temperature, transfer and x-rays collection at ambient temperature. (Abstract shortened by UMI.)

The objective of the research that I have undertaken was to develop two quantitative techniques used in analytical electron microscopy, energy dispersive X-ray microanalysis (EDX) and electron energy loss spectroscopy (EELS) and to apply those techniques to a selected biological system. More specifically the aim was to develop a technique for quantifying, at high spatial resolution, trace concentrations of Al in mineralised bone. The Al was highly localised and therefore it was important to select the microanalytical technique with the required spatial resolution (m) compatible with the highest sensitivity. In practice, the choice was relatively simple because the signals from the trace concentrations could not be detected using EELS due to the combined effects of plural inelastic scattering in the sample, and a low signal to background ratio. The former problem resulted from the difficulty in preparing sufficiently thin samples, and the latter is an inherent problem of EEL spectroscopy. Therefore, EDX was chosen for the mineralised bone study. As is always the case, artefacts are introduced into the spectral data by the measurement system itself and it was necessary to first quantify these artefacts before attempting to process the EDX spectra. Standards of accurately known composition are often used to quantify the characteristic signals extracted from EDX spectra. Unfortunately, suitable standards were not available for the elements of interest. Therefore, a standardless quantitation procedure was used. Since the accuracy of the method was dependent upon the accuracy of the parameterised characteristic cross-sections, some time was spent determining the optimal parameterisation. Significant problems exist when attempting to extract the Al and Mg signals from the EDX mineralised bone spectra. Essentially these are due to the extensive overlap between the major P peak and the vanishingly small Al (and Mg) signals of interest. In addition it is difficult to model the bremsstrahlung background (for characteristic signal extraction) at the Al and Mg X-ray energies because of the combined effects of absorption in the detector and specimen, and incomplete charge collection in the detector. However, a technique was developed which greatly improves the accuracy of the characteristic signal extraction over existing methods. A new method of EEL spectral processing was developed in which the characteristic signals are separated from the background counts and quantified in a single process. This `single-stage' technique appears to have some advantages over the standard `extrapolation' method of spectral processing: e.g. when dealing with adjacent edge signals or small signals on relatively large backgrounds. A detailed investigation was made into all the problems associated with the application of EELS to the mineralised bone study of interest here; i.e. the difficulties of EEL mineralised bone specimen preparation and the very low Al signal/background ratio which is predicted, even if suitable mineralised bone samples could have been prepared. Finally, a brief investigation was made into the physiological implications of the mineralised bone atomic ratios obtained in the EDX study.

La problématique des émissions de particules fines, posant des risques sanitaires et environnementaux avérés, a été très médiatisée ces dernières années. La solution mise en place consiste à aider financièrement les particuliers pour renouveler le parc d’appareils. Or, une utilisation non optimisée d’un appareil dégrade de manière significative ses émissions. Afin d’amender entre autres cette réflexion, de nombreuses campagnes expérimentales ont été menées au travers de caractérisations physico-chimiques complètes et innovantes des fumées, en particulier des particules fines : la Microscopie Electronique à Balayage, la microanalyse X et la détermination du type de carbone constitutif (Carbone Elémentaire, Carbone Organique). En premier lieu, la définition des paramètres d’utilisation de l’appareil et leurs niveaux de réponse ont permis de proposer une réduction significative des émissions dont celles de particules fines. Ainsi, les impacts des paramètres comme la nature du combustible, le mode d’allumage et l’injection d’air secondaire ont été quantifiés. Ensuite, les mécanismes de formations des particules ont été définis. Dans un second temps, ce travail de thèse s’est intéressé à l’évolution des caractéristiques des particules entre la chambre de combustion de l’appareil et le champ proche, permettant d’aller au-delà de l’étude normative classique. De nouveaux savoirs sur les particules ont ainsi été mis en évidence. L’ensemble de ces nouvelles connaissances, aidant à mieux connaître les particules produites par la combustion de bois dans des appareils indépendants, permettront dans le futur de créer des systèmes de traitement spécifiques et efficaces
The issue of the emissions of fine particles, known for their health and environmental hazards, has been significantly covered in recent years. The governments made the decision to help mainly financially the private individuals in order to renew the domestic appliances stock. However, a non-optimized use of an energy-efficient appliance can degrade system performances. In order to solve this issue, many experimental campaigns have been achieved through complete and innovative physicochemical characterizations of the smoke, especially of the fine particles : Scanning Electron Microscope, X-ray microanalysis and assessment of the constitutive Carbon (Elemental Carbon, Organic Carbon). First of all, the definition of the use parameters for the appliance and their impacts allowed offering a significant reduction of the fine particles emissions. In this work, the influences of the parameters such as the nature of the fuel, the ignition mode and the air secondary injection were in this way quantified. In order to better understand the origin of these emissions produced regardless of the combustion quality, the mechanisms of formation of all kinds of particles were defined. In a second phase, this work paid attention to the evolution of the characteristics of particles from the combustion room to the near-field. This enabled to go over the classic normative study. New knowledge on particles was brought to light, helping to better know the particles generation from domestic wood appliances. This could allow in the future to create some specific and efficient treatment systems

The present study is a microanalytic analysis of the communicative interaction between Inuit caregivers and their children at 16 and 20 months of age. The caregivers in the study included an older more traditional mother, a younger less traditional mother, and a teenage sibling caregiver. Videotaped samples of naturalistic interaction between the Inuit caregivers and children were coded for communicative intent using the Inventory of Communicative Acts-Abridged (Ninio, Wheeler, Snow, Pan, & Rollins, 1991). Preliminary comparisons between the Inuit data and the results of studies of white middle-class caregiver-child interaction were also assessed. Results of the study demonstrate that there are differences in caregiver-child interaction within the Inuit culture and between the Inuit and the white-middle class culture. The implications of these findings for interactionist theories of language acquisition such as Bruner's Language Acquisition Support System (1981, 1985) are discussed.

The overview of the history of quantitative x-ray microanalysis shows the efficiency of the use of standards to achieve the most reliable quantification. State-of-the-art cold field emission gun scanning electron microscopes offer excellent resolution but lack a sufficient level of beam current stability essential for reliable quantitative microanalysis. The purpose of this work is to develop a new method for quantitative x-ray microanalysis adapted to unstable beam current conditions.
In the Cliff and Lorimer method, which was developed for the analytical transmission electron microscope, the composition was calculated from the ratio of the characteristic x-ray intensities of two elements in the same spectrum. In this work, this ratio method is applied to bulk specimens in a scanning electron microscope (SEM). In order to reduce the amplitude of error propagation, the proposed ratio for SEM quantitative microanalysis is the intensity of a x-ray divided by the sum of intensities of one or more characteristic lines of each of tire elements found in the specimen. Moreover, the calculated x-ray intensities are corrected for the effects of absorption, fluorescence and Coster-Kronig yields, and other physical factors normally considered in microbeam analysis. Uncertainties in physical parameters and models, clue to the lack of exhaustive measurements as well as their scattering, revealed by a disaggrement between the measured and calculated ratios, are minimized by the use of a calibration factor inserted into the ratio. This calibration factor is determined using a standard for a given element. It can be used as often as needed and allows for the correction of uncertainties in the x-ray detector efficiency. In order to quantify the specimen, the measured experimental ratio is compared to a simulated ratio with the appropriate calibration factor. The composition is interpolated from the theoretical ratio curves. Two methods of calculation of emitted x-ray intensity are proposed, by analytical calculations using the Pouchou and Pichoir model or by an in-house developed Monte Carlo simulation program. Two sets of National Bureau of Standards (NBS) microanalysis standard reference materials, AuCu (SRM 482) and AuAg (SRM 481), are used to validate this method.
The comparison of calculated composition with the nominal one underlines the need for a beam-energy-dependent calibration factor, particularly because of ionization cross-section uncertainties. The use of high energy characteristic x-ray lines (above 5 keV) permits accuracy around 3% with a beam-energy-dependent calibration factor. The effects of beam energy, ionization cross-section models, mass-absorption coefficients and x-ray generation methods are compensated by the appropriate calibration factor. The change of the family of characteristic lines affects the accuracy. Finally, as in any quantitative microanalysis, the use of a filter to extract the characteristic intensity causes errors for low energy peaks. The analysis of the effect of calibration factors and mass-absorption coefficient enhances the need for refining the x-ray generation and emission parameters.
The error propagation is less important than if using the classical Cliff and Lorimer method in a SEM. However, the use of appropriate calibration factors and pair of lines offers promising accuracy in almost any conditions. This method is independent of the beam current, which is the purpose of this work. Despite many uncertainties of physical parameters, this method offers an efficient and reliable alternative to quantitative x-ray microanalysis with any electron microscope. Although developed for a binary material, the method can be extended to heterogeneous, rough, multiple-component materials, inasmuch as it can be simulated with a Monte Carlo program or any other method that computes characteristic x-ray lines intensities.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 2013.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 127-134).
Antibodies are higher order protein structures produced by a subset of lymphocytes (B cells) in the immune system for protection against pathogenic species. These homodimers of heterodimers form highly specific interactions with their cognate antigens and hence have become very important for the development of prophylactic or therapeutic agents against different disease pathogens. A key step in the development of human monoclonal antibodies as therapeutics is identification of candidate antibodies either by direct screening of human antibody repertoires or by filtering through combinatorial libraries of human variable genes using display technologies. Combinatorial libraries of human variable genes afford the flexibility to pursue many targets of interest, but often result in the selection of low affinity antibodies or unnatural heavy and light chain pairings that would have been selected against in vivo. With direct screening of the human B cell repertoire, the challenge is how to efficiently isolate clones of interest. Presented in this thesis is a high-throughput, integrated, single-cell methodology based on microengraving that allows the rapid recovery of antigen-specific human B cells. Microengraving is an analytical technique wherein secreted molecules from individual cells seeded into a dense array of subnanoliter wells are captured on the surface of a glass slide, generating a microarray from which desirable cells can be identified and recovered. Combined with high resolution epifluorescence microscopy and single-cell RT-PCR, we have developed assays for the simultaneous profiling of surface-expressed phenotypes of primary antibodyproducing cells, as well as functional characteristics of their secreted antibodies and germline variable gene usage. Using clinical samples from HIV- and West Nile virus-infected subjects, we demonstrate that the method can identify antigen-specific neutralizing antibodies from both plasmablast/ plasma cell and memory B cell populations, and is ideal for the detailed characterization of cells from anatomical sites where sample sizes are often limited and disease pathophysiology is poorly understood (e,g. gut tissue, bone marrow).
by Adebola O. Ogunniyi.
Ph.D.

Thesis advisor: Gregory McMahon
Thesis advisor: Barbara Adams Hebard
A terracotta portrait bust of the Marquis de Lafayette with the signature “houdon an. 1790”, now broken, was given to Boston College by Edward S. Ryan in 1966. The two objectives of this study were: (1) To determine the methods used to create this bust and (2) whether or not it could have been made in the studio of Jean-Antoine Houdon. A materials analysis using Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDS) was performed on five representative samples from different regions of the bust. Three samples were unpolished and two were polished using an argon beam milling technique, completely preserving the heterogeneous samples. It was found that the bust was created by pressing wet clay into piece mold, the waxy surface is not original to the sculpture, and the pink layer is the result of a higher iron particle concentration. It is almost impossible to absolutely determine whether or not Houdon made the bust, due to uncertainties in provenance and the large number of busts made by, and copied from, Houdon. However, it is clear that the materials original to the sculpture correlate with the time Houdon lived and the methods he used
Thesis (BS) — Boston College, 2011
Submitted to: Boston College. College of Arts and Sciences
Discipline: College Honors Program
Discipline: College Honors Program

Bibliography: pages 94-99.
This thesis describes work performed to establish and demonstrate a quantitative trace element microanalysis technique for geological material using protons accelerated by the Van de Graaff Accelerator at the National Accelerator Centre (NAC) in Faure near Cape Town. The method relies on the analysis of Proton Induced X-ray Emission (PIXE) spectra, interpreted with the help of the GeoPIXE software package. The use of the Si(Li) energy dispersive detector provides simultaneous multi-element detection at the parts-per-million (ppm) level, and a scanning beam facility permits trace element distributions to be studied at these levels. The calibration of the detector efficiency and the thicknesses of selectable X-ray attenuating filters was performed using pure elemental samples. This involved the accurate determination of the target to detector distance, the thickness of the active volume of the Si(Li) detector crystal, the thicknesses of all the absorbing layers between the sample and the detector crystal, and the assessment of the effects of incomplete charge collection in the detector.

"Radionuclides in particulate matter associated with outdoor and indoor dusts were analyzed to determine the form and concentration of radioactive isotopes present. These radioactive isotopes, such as Strontium 90, Cesium 137, and Uranium 235, consist of, or are sorbed onto fine particulate matter, (PM). The airborne dispersion of this fine particulate matter results in the facilitated transport of these sorbed or neat radionuclides. Sources of particulate-bound radioactive contaminants include fallout from weapons testing, accumulation of radon daughters, transport of soils containing naturally-occurring radioactive material, remediation of radiologically-contaminated sites, and nuclear material processing. Radiological contaminants in PM, may exist as trace contamination in homogenous collections of particles, but may also exist heterogeneously, as a small number of high-concentration radionuclides among a larger set of uncontaminated particles. A total of 114 samples of indoor and outdoor airborne dusts were collected from a former nuclear weapons production facility near Richland, WA, the Los Alamos National Laboratory, and the Yakama Indian Nation in Wapato, WA. Los Alamos, NM was also the site of the May 2000 Cerro Grande wildfire. The wildfire created very large amounts of airborne particulate matter, including smoke and soot. The area affected by open burning included 43,000 acres. At the national laboratory, greater than 7600 acres were affected, including some areas that were radiologically- contaminated, such as a U-238 ammunition firing area. (LANL, 2007) This introduces a potential source of hot particles in dusts and other archived particulate matter, which may remain in the environment. LANL Airborne radionuclide surveillance has historically found higher uranium levels during windy periods, and saw elevated air uranium levels associated with the Cerro Grande fire. (Ibid, p. 108) Dust samples were sieved to pass a 150 micron screen and analyzed by gamma spectroscopy. Samples with higher activity were analyzed by Scanning Electron Microscopy/Energy Dispersive X-ray analysis, SEM/EDS. The results of gamma spectroscopy and individual particle counts were compared to determine the degree of radioactive heterogeneity in each sample. Radioactive heterogeneity, isotopic distribution, and particle size can be related to the source of the radioactive PM. Radiological contaminants in particulate matter, (PM), may exist as trace contamination in homogenous collections of particles, but may also exist heterogeneously, as a small number of high-concentration radionuclides among a larger set of uncontaminated particles. Residential and source area dusts were collected from locations surrounding, and potentially impacted, by operational and remedial activities at the HNR. The dust samples were analyzed, by multiple means, in order to identify those with radiologically- contaminated particles. Samples with higher activity were further analyzed by Scanning Electron Microscopy/Energy Dispersive X-ray analysis, (SEM/EDS), to determine if the radiological contamination was homogenous or heterogeneous. Two case studies were followed. The method isolated and analyzed lead and bismuth from naturally occurring radioactive material in coal fly ash. The method isolated and fingerprinted thorium, and the rare earths cerium, lanthanum, samarium, neodymium, and gadolinium in sedimentary cerium monazite minerals, nuclear waste processing dusts, and fission waste products in a WWTP effluent channel."

L’objet de l’étude concerne la caractérisation physico-chimique des revêtements superficiels par microanalyse x et son application a l’étude des revêtements prothétiques phosphocalciques. Nous avons étudies les mécanismes de formation des phosphates de calcium par electrodeposition. Nous avons vérifie les hypothèses avancées par une étude portant sur l’influence de la densité de courant sur les phosphates de calcium électrodéposés. Pour caractériser ces revêtements, nous avons développé une méthodologie en microanalyse x basée sur la complémentarité de la microscopie électronique a balayage et de la microscopie électronique a balayage transmission. Par la suite, nous nous sommes intéressés aux cartographies quantitatives des films minces sur substrats. Nous avons illustre l’impact de l’hétérogénéité du substrat sur la quantification des films minces ; puis, nous avons présente TF_Quantif, l’algorithme de quantification (concentrations et épaisseurs) que nous préconisons pour s’affranchir de ces problèmes. Nous avons aussi mené une étude théorique pour déterminer les limites d’application de TF_Quantif. Enfin, nous avons présenté les développements logiciels et instrumentaux nécessaires a l’utilisation de TF_Quantif et nous avons effectue des profils et cartographies quantitatifs sur des films minces (de composition et d’épaisseur connue) sur substrats hétérogènes ainsi que sur un revêtement de phosphate de calcium. Les résultats ont été compares avec ceux obtenus par un logiciel de quantification que nous avons développé a partir du logiciel commercial STRATAGem (SAMx, France)
This work deals with electron probe microanalysis of thin films and its application to thickness and concentration determination in the case of prosthetic calcium phosphate coatings. In a first part, we have studied the formation mechanisms of calcium phosphate elaborated by electrodeposition. We carried out a methodology based on the complementarities of scanning electron microscopy and scanning transmission microscopy both associated to x-ray microanalysis. This method allowed us to verify our hypothesis about calcium phosphate formation and showed that the current density is directly connected to the kind of electrodeposited calcium phosphate. In a second part, we have carried out quantitative elemental mapping of thin film on heterogeneous substrate. Through different examples, we showed that substrate heterogeneity has a direct influence on the thin film quantification. We developed a new quantification algorithm called “tf_quantif” which allows us removing substrate effects during the analysis associated to a theoretical approach which determine the thickness limit of this method. Moreover, we presented the quantification software and experimental setup developed in order to use “tf_quantif”. Finally, we applied “tf_quantif” on quantitive profiles and maps on several kinds of thin films on heterogeneous substrate (including electrodeposited calcium phosphate coatings). The results were compared to those obtained from commercial software (stratagem, samx, france). We showed that our quantification algorithm gave better results in the case of thickness determination and could be successfully applied in the case of quantitative maps of thin film on heterogeneous substrate