The need for non-contact micromanipulation methods is apparent for a number of different applications. Optical tweezers, a technique which uses highly focused laser beams to trap and move microscopic objects, has become an important tool for many applications owing to its incredible precision and dexterity. Optical trapping is, however, limited in several ways. It often struggles with particles larger than 10 micrometers, agglomerates and large numbers of particles. Complimentary technologies such as acoustic trapping, aim to overcome some of these limitations. This technique, also termed as Sonotweezers, uses ultrasonic fields to manipulate particles and can manipulate large particles with ease and manipulate large numbers of polydisperse particles and agglomerations, although they currently lack the dexterity of optical tweezers. Combining these two trapping modalities overcomes the some of the limitations of both of them and opens up a new range of useful applications. Three main types of hybrid optical and acoustic traps have been devised and are presented here. The first is an acoustic Bessel beam trap which is used to arrange a large number of polydisperse particles into concentric rings whereupon the smaller particles can then be further manipulated using a single beam optical tweezer. A rudimentary optical sorting system, which pushes particles in a flow laterally using an optical trap, has been combined with an acoustic levitator, which moves all particles away from the edges of the microfluidic channel reducing on sticking and other negative effects. A novel optically transparent ultrasonic device has been developed for easier integration into optical traps without the need for modication. This transparent trap has also been used in combination with a multibeam interference optical sorter to improve the separation between 5 and 10 micron particles.

Neste trabalho, foi realizado o crescimento de nanotubos de carbono pela técnica de deposição química a vapor (CVD) térmica catalítica, utilizando-se filmes finos de níquel como material catalisador, gás metano (CH4) como fonte de hidrocarboneto e nitrogênio (N2) como gás de arraste. Amostras processadas sobre filmes de Ni de 15 nm de espessura, depositados sobre substrato de óxido de silício (SiO2), com temperatura de processo de 900 ºC e tempo de 15 minutos promoveram uma maior densidade de síntese de nanotubos de carbono, utilizando-se um fluxo na proporção de 2 partes de N2 para 1 parte de CH4. Comprovou-se sua síntese através da visualização de sua morfologia por microscopia eletrônica de varredura (SEM) e microscopia eletrônica de transmissão (TEM), além da extração de seu espectro característico por espectroscopia Raman e espectroscopia de dispersão de raio-X (EDS). Em um segundo estudo, depositaram-se sobre substratos de vidro filmes transparentes e condutores (TCF) à base de nanotubos de carbono de paredes múltiplas (MWCNT) comerciais, pela técnica de dip coating. Para isso, realizou-se a dispersão dos nanotubos sob diversas concentrações em água deionizada (DI) com o auxílio do surfactante dodecil sulfato de sódio (SDS), com posterior funcionalização através do ataque químico por ácido nítrico (HNO3), visando sua aplicação na fabricação de células solares. Foram utilizados os equipamento de quatro pontas e curva corrente x tensão (IV) para caracterização elétrica, transmitância por espectrofotometria para caracterização óptica, SEM para a visualização de sua morfologia e espectroscopia Raman para a análise química de suas estruturas. Valores de resistência de folha de 2x105 W/ e transmitância de 65% foram obtidos nas amostras mais concentradas, com 0,2 mg de nanotubos por ml de água DI. Uma etapa de limpeza em água DI pós deposição foi feita para remoção do excesso de surfactante presente no filme, o que prejudica tanto as características elétricas e ópticas, por ser um dielétrico e não ser transparente. Essa limpeza melhorou o valor de transmitância, porém aumentou a resistência de folha, devido à remoção parcial dos nanotubos presentes no filme, interrompendo em certos pontos a malha que promovia a passagem de corrente elétrica. O ataque químico por HNO3 promoveu a criação de algumas quebras na estrutura do carbono, o que é verificado pelo aumento da banda D, característico da presença de defeitos. / In this work, the growth of CNTs was investigated, using chemical vapor deposition (CVD) thermal catalytic technique, carried out by utilizing thin films of nickel as catalyst material, methane (CH4) as hydrocarbon source and nitrogen (N2) as carrier gas. Samples processed onto 15 nm thick Ni films, deposited on silicon oxide (SiO2) substrates, at a temperature of 900 °C for 15 minutes, promoted a higher density of carbon nanotubes, using a gas mixture at the ratio of 2 parts of N2 and 1 part of CH4. This was verified by analysing the nanotubes morphology by scanning electron microscopy (SEM) and transmission electronic microscopy (TEM) and by the extraction of its characteristic spectrum by Raman spectroscopy and energy dispersive spectroscopy (EDS). In a second study, transparent conductive films (TCF) based on commercial multi-walled carbon nanotubes (MWCNT) were deposited on glass substrates by the dip coating technique. To do so, carbon nanotubes (CNTs) with different concentrations were dispersed in deionized water (DI) with the addition of the surfactant sodium dodecyl sulfate (SDS), and subsequent functionalization through chemical attack by nitric acid (HNO3), aiming their application in solar cell fabrication. The four point probe equipment and current x voltage curve (IV) was used for electrical characterization, transmittance for optical characterization, SEM to visualize their morphology and Raman spectroscopy for chemical analysis of their structures. Sheet resistance values of 2x105 W/ and transmittance of 65% were obtained in the most concentrated samples, with 0.2 mg per ml of nanotubes in deionized water (DI). A cleaning stage in DI water after deposition was taken for removal of surfactant excess in the film, which harms both the electrical and optical characteristics, as it is a dielectric and not transparent. This cleaning improved the transmittance value, but increased the sheet resistance due to partial removal of the nanotubes in the film, interrupting at certain points the mesh of CNTs that promoted the passage of electric current. The chemical attack by HNO3 promoted the functionalization by creating some breaks in the carbon structure, which is checked by the observation of the increasing in D band, which is characteristic of defects.

Hydrogen exposure of insulating d0-titanates, such as SrTiO3 (STO), has displayed the formation of intriguing conducting states. These conducting states form through the use of forming gas (N2/H2) annealing or hydrogen plasma exposure, where hydrogen gas is exposed to high energy microwaves. The exposure of STO to hydrogen causes metallic conductivity due to the introduction of hydrogen cations on some of the oxygen sites. However, the optical properties of this hydrogen-exposed STO have not been well-studied. Further, Ba0.5Sr0.5TiO3 (BST), an insulating dielectric, also shows changes in its conductivity upon hydrogen exposure. Unlike STO where the conductivity of the hydrogen-exposed material has been characterized, the optical, electronic, and transport properties of hydrogen exposed BST have not been studied. Thus, by studying hydrogen-exposed BST and STO, our understanding of the effects of hydrogen on insulators can be enhanced. In the first study, the effects of the exposure of insulating dielectric BST thin films to a hydrogen plasma is presented. These BST thin films are deposited on GdScO3 (GSO) substrates via Pulsed Laser Deposition (PLD). After deposition, the thin films are exposed to a hydrogen plasma. Just five minutes of hydrogen plasma exposure is enough to induce conductivity in the BST thin film. This conducting state is dominated by the interplay of disorder and strong electron correlations introduced during hydrogen exposure. Further, the optical properties indicate the formation of a transparent conductor, as the introduction of disorder and strong correlations has not changed the optical properties of the BST thin film in the visible spectrum. BST demonstrates an example of a new type of transparent conductor that utilizes large effective mass carriers to generate conductivity. In the second study, the effects of hydrogen doping on the surface of STO is explored. The conducting heterointerface that forms between PLD-deposited thin films of LaAlO3 (LAO) on STO is used as the standard to explore this hydrogen surface doping. The optical, electronic, and transport properties of water-leached and buffered hydrofluoric acid (BHF) etched heterointerfaces are characterized and compared. The recently developed water-leaching method is compared with the well-known BHF etching method, which has been shown to unintentionally dope the STO surface with fluorine and hydrogen. Both methods generate single-terminated atomically flat STO substrate surfaces that are ideal for heterointerface formation. After deposition, the optical, electronic, and transport properties of both the water-leached and BHF-etched heterointerfaces show no meaningful difference, demonstrating that water-leaching may also unintentionally dope the STO substrate surface with hydrogen. However, these results confirm that water-leaching generates a high-quality conducting heterointerface without the safety concerns of BHF.

The current study investigates the effect of auditory and visual speech information and orthographic information on second/foreign language (L2) acquisition. To test this, native speakers of Turkish (a language with a transparent orthography) and native speakers of Australian English (a language with an opaque orthography) were exposed to Spanish (transparent orthography) and Irish (opaque orthography) legal non-word items in four experimental conditions: auditory-only, auditory-visual, auditory-orthographic, and auditory-visual-orthographic. On each trial, Turkish and Australian English speakers were asked to produce each Spanish and Irish legal non-words. In terms of phoneme errors it was found that Turkish participants generally made less errors in Spanish than their Australian counterparts, and visual speech information generally facilitated performance. Orthographic information had an overriding effect such that there was no visual advantage once it was provided. In the orthographic conditions, Turkish speakers performed better than their Australian English counterparts with Spanish items and worse with Irish terms. In terms of native speakers' ratings of participants' productions, it was found that orthographic input improved accent. Overall the results confirm findings that visual information enhances speech production in L2 and additionally show the facilitative effects of orthographic input in L2 acquisition as a function of orthographic depth. Inter-rater reliability measures revealed that the native speaker rating procedure may be prone to individual and socio-cultural influences that may stem from internal criteria for native accents. This suggests that native speaker ratings should be treated with caution. / Master of Arts (Hons)

People rely on off-the-shelf commercial single-user software systems in their daily lives and work to perform single-user tasks. People also need groupware systems to perform collaborative or group tasks. The goal of this thesis work is to develop innovative techniques for building computer applications that combine conventional single-user functionalities with advanced collaboration capabilities to effectively support people's individual and group work. This thesis work contributes an innovative Transparent Adaptation (TA) approach and associated supporting techniques that can be used to convert existing or new single-user applications into real-time multi-user collaborative versions without changing their source code. The transparently adapted collaborative systems not only support unconstrained collaboration and other collaboration features that were previously seen only in advanced groupware research prototypes, but also maintain the conventional functionalities and interface features that were previously seen only in commercial off-the-shelf single-user applications. Major technical contributions of the TA approach include techniques for adapting the single-user application programming interface to the data and operation models of the underlying generic collaboration technique and a generic system architecture for collaborative systems. The Operation Transformation (OT) technique has been chosen as the underlying collaboration technique for the TA approach due to its capability of supporting unconstrained collaboration and application independence. This thesis work has also made important contributions to OT by extending OT from supporting only collaborative plain text editing to supporting collaboration on complex data structures and comprehensive functionalities. To support the adaptation of complex data and operation models in a range of applications, this thesis work has contributed a package of advanced adaptation techniques for collaborative table editing and graphic object grouping. These techniques have not only increased the capability of TA, but have also advanced the state-of-the-art of collaborative editing techniques. To facilitate natural and smooth collaboration, this thesis work has contributed a multi-functional workspace awareness framework which is able to reduce the effort for developing workspace awareness features, and to be extended to support new workspace awareness features. Most importantly, this framework is able to deliver correct and precise workspace awareness information in the face of dynamic content and view changes in TA-based systems, which is an innovative feature unavailable in existing techniques. The TA approach and supporting techniques were developed and tested in the process of transparently converting two commercial off-the-shelf single-user applications - Microsoft Word and PowerPoint - into real-time collaborative applications, called CoWord and CoPowerPoint, respectively. CoWord and CoPowerPoint not only retain the functionalities and the 'look-and-feel' of their single-user counterparts, but also provide advanced multi-user collaboration capabilities for supporting multiple interaction paradigms, ranging from concurrent and free interaction to sequential and synchronized interaction, and for supporting detailed workspace awareness, including multi-user tele-pointers and radar views. The TA-based collaborative system architecture and the generic collaboration engine software component developed from this work can be reused in adapting a wide range of single-user applications.

An underlying issue which inheres in any taxation framework relates to the manner in which it operates and the actual distribution of its imposts or appropriations. In this respect, a tax system needs to confront two fundamental (and interrelated) questions – first, precisely how the tax or impost should be imposed and, secondly, who should bear the legal obligation or onus of payment. These issues can be conceptualised not only from a purely legal or positivist perspective, in terms of identifying who will incur the obligation to pay tax, but also in terms of a more economic and instrumental standpoint as to which entity or individual should effectively be paying the tax. These alternatives may not result in the same conclusions, particularly for the taxation of business forms. To provide one example, if the business form has separate legal entity status from its members, should the business form, as a legal person, be subject to tax separately from its members? From a legal standpoint the response to this question is that such a business form should bear the impost. However, from an economical perspective it may be preferable that the business income and/or losses are directly allocated to its members. Indeed, tax transparency (aggregate approach) has been argued as an economically superior model, although it is not without its critics...

Offrir un accès transparent et sécurisé à un ensemble de ressources passe par la définition de logiciels de médiation qui rendent la complexité de l'architecture sous-jacente transparente à l'utilisateur en offrant des facilités de conception, d'intégration, d'interrogation et d'administration permettant le partage de données et de programmes d'une manière fiable et efficace. Un très gros effort a été mené ces vingt dernières années pour aider à la mise en œuvre de ces logiciels de médiation, que cela soit par la communauté bases de données ou par la communauté systèmes distribués. Ces deux communautés adressent différemment le problème de l'accès transparent et sécurisé à des ressources largement distribuées, il est donc important aujourd'hui de comprendre la variabilité des solutions en termes de fonctionnalités, de design, d'algorithmes et d'architectures afin d'identifier les différentes dimensions du problème. <br />Ce mémoire retrace l'ensemble de mes activés de recherche réalisées à partir de 1992 au sein du thème SBD (Systèmes et Bases de Données) du laboratoire PRISM de l'Université de Versailles-St-Quentin, et depuis 2002, dans le cadre du projet SMIS (Secure & Mobile Information System) à l'INRIA. Il détaille les aspects pluridisciplinaires de l'accès transparent aux données comme la conception et le développement de systèmes de médiation de données pour l'interopérabilité de bases de données relationnelles, objets et XML, et la problématique d'accès aux données dans les systèmes à objets distribués à l'aide d'annuaires. Il aborde également la problématique d'accès sécurisé aux données, notamment dans un contexte XML. <br />Ce mémoire détaille l'ensemble de mes contributions scientifiques autour de ces trois thèmes, indique pour chacun d'eux le contexte historique de l'époque et le replace vis-à-vis de l'existant. Pour conclure, il liste un ensemble de perspectives et directions de recherche à la lueur de mon expérience pluridisciplinaire et du constat de l'adoption croissante de XML comme fondation technologique pour l'accès transparent et sécurisé aux données largement distribuées.

De nombreuses études ont été réalisées autour du problème du routage et de l'affectation de longueur d'onde dans les réseaux WDM transparents. La majorité de ces études néglige les effets physiques liés à la transmission sur fibre. En effet, le signal optique subit le long de son trajet plusieurs dégradations, à savoir les effets linéaires et les effets non-linéaires. Dans les réseaux WDM opaques, la qualité du signal optique est considérée comme toujours satisfaisante car le signal est régénéré à chaque nœud du réseau. Cependant, cette faculté de régénération coûte très cher à l'opérateur et rigidifie totalement la capacité du réseau. Les réseaux WDM translucides présentent une nouvelle alternative. Ils offrent la possibilité de régénérer le signal à un nœud intermédiaire dès que la qualité de celui-ci devient inadmissible par rapport aux contraintes imposées par l'opérateur. Dans cette thèse, on s'intéresse au problème de la planification des réseaux WDM translucides de façon à garantir une certaine qualité de transmission. Nous proposons un nouvel outil de dimensionnement, LERP (Lightpath Establishment and Regenerator Placement), dont l'objectif est de fournir une solution permettant d'optimiser à la fois l'utilisation des ressources du réseau et la qualité de transmission sur l'ensemble de connexions établies. Le facteur Q permettant d'évaluer la qualité du signal est calculé au moyen d'un outil que nous avons également développé : BER-Predictor. Cet outil tient compte de quatre dégradations liées à la transmission sur fibre, à savoir la dispersion chromatique, la dispersion modale de polarisation, la phase non-linéaire et l'émission spontanée amplifiée.

The focus of this thesis involves development of highly transparent, n-channel, accumulation- mode thin-film transistors employing a zinc tin oxide (ZTO) channel layer. ZTO-based transparent thin-film transistors (TTFTs) show improved device performance compared to ZnO-based TTFTs. An estimated peak effective mobility for these devices as high as ~100 cm² V⁻¹sec⁻¹ has been observed, although effective mobilities in the range of 20-50 cm²V⁻¹sec⁻¹ are more common. This performance inconsistency may be due, in part, to the large device dimensions employed in developmental test structures and/or to shadow mask misalignment. Typical drain current on-to-off ratios are > 10⁶. Variation in the post-deposition annealing cycle is found to be an effective means to control the threshold voltage and to improve device performance. Optical characterization of these devices indicates ~84% transparency in the visible spectrum as viewed through the source/drain. Another aspect of this thesis research involves the utilization and extension of quantitative polycrystalline TFT device models with the intention of guiding the design and optimization of future TFTs. In particular, subthreshold conduction is assessed in order to estimate the bulk (and/or grain boundary) and interface trap densities. This leads to a consideration of threshold voltage and channel mobility extraction, as well as establishment of the turn-on voltage, V[subscript turn-on] Finally, a third aspect of this thesis research involves a new radio-frequency (RF) magnetron sputtering system, custom-designed and constructed at OSU by Chris Tasker. Contributions to the development of this tool include assisting in the design and implementation of the computer-controlled interlocks utilized for operation of the tool. The experimental flexibility of this new tool is discussed with respect to its applicability in the design and fabrication of future TTFTS. / Graduation date: 2004

Coccolithophores are unicellular microscopic algae (Haptophyta) surrounded by calcium carbonate plates that are produced during their life cycle. These species, whose contemporary contributor is Emiliania huxleyi, are mainly found in the sub-polar and temperate oceans, where they produce huge blooms visible from space. Coccolithophores are sensitive to ocean acidification that results from the ongoing accumulation of anthropogenic carbon dioxide (CO2) in the atmosphere. The response of these organisms to global change appears to be related to the reduction of their ability to produce calcium carbonate at the cellular level. At the community levels, one anticipates changes in the carbon fluxes associated to their blooms as calcification is reduced. However, the consequences of such environmental changes on this species are speculative and require improvements in the description of the mechanisms controlling the organic and inorganic carbon production and export. The first aspect of this work was to study the response of these organisms to artificially modified CO2 concentrations representative of the conditions occurring in the past (glacial) and those expected by the end of the century (2100). Two different levels were examined: the continuous monospecific cultures (chemostats) allowed us to work at the cellular level while the mesocosms gave light to the mechanisms taking place in an isolated fraction of the natural community. The second aspect of this work consisted of field studies carried out during four cruises (2002, 2003, 2004 and 2006) in the northern Bay of Biscay, where the occurrence of E. huxleyi blooms were observed in late spring and early summer. We describe the vertical profiles of biogeochemical variables (nutrients, chlorophyll-a, dissolved inorganic chemistry, particulate carbon, transparent exopolymer particles (TEP)) and study processes such as primary production, calcification and bacterial production. The properties of these blooms are compared with those reported in the literature and enriched with original measurements such as the abundance and concentration of TEP that could play an important role in carbon export to the deep ocean, modifying the properties of the settling ballasted aggregates.