In this thesis, a microsimulation model was developed using methods which were intended to overcome the main criticism of earlier models developed in Australia - that their estimation of the distribution of health benefits1 across income groups was not accurate. To determine whether the new model � called the Person Level Model of Pharmaceutical Benefits (PLM-PB) � was more accurate, two typical means-based models were also built to replicate the most commonly used methods in Australia. A comparison of the results of the three models revealed that while they produced comparable results at the aggregate when compared with administrative data, the PLM-PB was much more accurate in capturing distributional differences by beneficiary and medication type. The PLM-PB also indicated that, as anticipated, PBS benefits were more pro-poor than earlier means-based models had suggested. The PLM-PB had another important advantage in that the method also captured the variation in the use of medication and thus the subsidy received within sub-populations. As the PLM-PB was found to be more accurate than the means-based model, a multivariate analysis of the distribution of PBS subsidy across a number of socio-economic groups was undertaken as an example application of the model. It was found that health status (defined by number of recent illnesses) and concession card type were most important in explaining the amount of PBS subsidy received. This indicates that the distribution of PBS expenditure meets the policy objectives of assisting those most in need, whether need is defined as poor health or low income. 1 Benefits refer to expenditure as transfers from government to individuals rather than the general health benefits of using medication.

Polarization dependences of optical devices in highly-integrated optical systems become a major problem. To overcome this issue, one can implement polarization diversity scheme to achieve a single polarization on-chip network. One of the essential components in a polarization diversity scheme is the polarization beam splitter (PBS). In this thesis, we will a PBS based on a silicon-on-insulator (SOI) platform with reduced device size and broad operation bandwidth. We use the three-dimensional Finite-Difference Time-Domain (3D-FDTD) method to perform the simulation. First, we use two asymmetric waveguides to design an asymmetric directional coupler with only TE-like mode phase matching condition. We then tape the lower waveguide to keep the TE-polarized light, and split the TE- and TM- polarized light. By utilizing an asymmetrical directional coupler with a tapered waveguide, we have achieved a 7.3

abstract: Teachers use different rates of positive feedback with students who are high-risk for emotional and behavioral disorders (EBD) in comparison to the rates of positive feedback teachers' use with low-risk students. By addressing the differential treatment, it may alleviate some of the related negative effects students high-risk for EBD experience, such as poor educational and social outcomes. The study explored the extent of teachers' differential use of feedback toward students identified as high-risk and low-risk for EBD. The data were collected in 56 teachers' classrooms by measuring rates of feedback delivered to 1 high-risk and 1 low-risk student per classroom (112 students total). Results revealed that teachers used positive strategies infrequently with the students high- risk for EBD. Results further indicated that teachers were over reliant upon using negative feedback with high-risk students. Descriptive variables within the study, such as school-wide and teachers' self-evaluations of positive classroom strategies, schools' special education population, and suspension rates were further explored. Implications for professional practice and potential future lines of inquiry on the differential treatment of students at risk for EBD in educational settings are presented. / Dissertation/Thesis / Ph.D. Special Education 2011

Made available in DSpace on 2016-06-02T20:34:08Z (GMT). No. of bitstreams: 1 1951.pdf: 5829403 bytes, checksum: 71b2aeaac3ff3cb7d2f3ba4a25d21975 (MD5) Previous issue date: 2008-03-13 / Financiadora de Estudos e Projetos / This work describes studies on the underpotential deposition (UPD) of selenium, zinc, as well for Zn/Se systems deposited on polycrystalline Pt electrodes in acid solutions. The effects of Zn presence in the Se dissolution process were also investigated in the UPD and bulk potential range, 0.6 and 0.03 V respectively. The measurements were carried out using cyclic voltammetry and electrochemical quartz crystal microbalance (EQCM). Furthermore Lead sulfide (PbS) multilayers were grown on a single crystal Ag(111) substrate by Electrochemical Atomic Layer Epitaxy (ECALE) method. For Zn UPD in sulfuric acid, two different processes were observed, which are attributed to the dissolution of submonolayer of Znads and H-atoms adsorbed on the electrode surface. For Se UPD was observed that hydrogen desorption were completely inhibited indicating that Se film recovered the Pt surface. The deposition of UPD Se in perchloric acid solution showed the transference of 4 electrons with 1.4 and 1.12 active sites of Pt occupied by 1 Se ad-atom in the UPD and bulk potential range, respectively. In the evaluation of the Se monolayers dissolution process formed at 0.03 V during 2000 s a process not mentioned in the literature it was observed which was evaluated by the technique MECQ. The experimental results obtained by this technique allowed to end that the dissolution process occurred by two stages, and the first involved the participation of 6e-. The dissolution mechanism with 6e- happens with the participation of water in the dissolution process of Se, leading to the formation of an oxygenated selenium compound which in next step undergo slow oxidation and is dissolved as soluble Se(VI) species. Then the total dissolution process of Se occurs in a six-electron transfer reaction. For Se deposition in the Zn presence the dissolution charges associated with Se UPD increase, indicating that the presence of Zn favors the deposition of UPD Se. In the case of PbS multilayers on Ag (111) the voltammetric analysis of the first PbUPD and SUPD peaks indicates a mechanism of two-dimensional growth, which is consistent with epitaxial growth. Electrochemical stripping measurements indicate that the amount of Pb and S deposited in a given number of cycles is a function of the number of cycles employed, again suggesting a layer-by-layer growth. This result indicates that the amount of Pb and S in these films corresponds to the stoichiometric 1:1 ratio, indicating the formation of a compound. / Este trabalho descreve os estudos da deposicao em regime de subtensao (DRS) de Se, Zn, assim como para sistemas Zn/Se depositados sobre eletrodos policristalinos de Pt em solucoes acidas. Os efeitos da presenca de Zn no processo de dissolucao de Se tambem foram investigados em uma regiao de potenciais de DRS e deposicao massiva 0,6 V e 0,03 V, respectivamente. As medidas foram realizadas usando voltametria ciclica e microbalanca eletroquimica de cristal de quartzo (MECQ). Alem disso, multicamadas de sulfeto de chumbo (PbS) foram crescidas sobre substrato de Ag(111) utilizando o metodo de deposicao eletroquimica de camadas atomicas epitaxiais (ECALE). Para a DRS de Zn em meio de acido sulfurico dois processos distintos foram observados os quais foram atribuidos a submonocamadas de Znads e atomos de H adsorvidos sobre a superficie do eletrodo. Para a DRS do Se observou-se a inibicao completa da dessorcao de hidrogenio o que indicou recobrimento total da superficie de Pt por ad-atomo de Se. A deposicao de Se em meio de acido perclorico mostrou a transferencia de 4 eletrons com 1,4 e 1,12 sitios da Pt ocupados por cada ad-atomo de Se, em potenciais de deposicao em DRS e sobretensao, respectivamente. Na avaliacao do processo de dissolucao das monocamadas de Se formadas a 0,03 V e por um tempo de deposicao de 2000 s um processo nao mencionado na literatura foi observado o qual foi avaliado pela tecnica MECQ. Os resultados experimentais obtidos por esta tecnica permitiram concluir que o processo de dissolucao do Se ocorria por duas etapas, sendo que a primeira envolvia a participacao de uma 6 eletrons e a segunda de 4 eletrons. O mecanismo de dissolucao com 6 eletrons ocorre com a participacao de agua no processo de dissolucao do Se, levando a formacao de compostos de Se oxigenados, os quais em uma etapa posterior sofrem uma oxidacao lenta e se dissolvem como especies soluveis de Se(VI). Entao o processo total de dissolucao de Se ocorre em uma reacao de transferencia de 6 eletrons. Ja para a deposicao de Se na presenca de Zn pode-se concluir, devido ao aumento da carga de dissolucao da DRS de Se, que a presenca de Zn favorece o processo de deposicao do Se. No caso das multicamadas de PbS o estudo voltametrico das primeiras camadas de Pb DRS e S DRS indicam um mecanismo de crescimento bidimensional, que e consistente com o crescimento epitaxial. As cargas medidas no processo de dissolucao das camadas indicaram que a quantidade de Pb e S depositados para um dado numero de ciclos e uma funcao do numero de ciclos realizados, sugerindo novamente um crescimento camada por camada Este resultado sugere que a quantidade de Pb e S nos filmes possuem uma relacao estequiometrica de 1:1, indicando a formacao de um composto.

Cette thèse consiste en une étude de jonctions tunnels à Quantum Dot (QD) unique. Le second chapitre présentera une introduction aux concepts fondamentaux nécessaires à la description d’une telle jonction. Dans le troisième chapitre, je décrirais les méthodes de fabrications et de mesures. Dans le quatrième chapitre, je décrirais une étude par spectroscopie tunnel de QDs PbS. Trois signatures distinctes du couplage électron-phonon sont observées dans le spectre tunnel. Dans le régime de « remplissage de couches », la dégénérescence d’ordre 8 des états est levée par les interactions de Coulomb et permet l’observation des sous-bandes de phonons résultant de l’émission de phonons optiques. A faible tension, une bande interdite (gap) est observée dans le spectre, laquelle ne peut être fermée avec la tension de grille, ce qui est une signature caractéristique du blocage de France-Condon. A partir de ces données, un facteur de Huang-Rhys de l’ordre de S~1.7-2.5 est obtenu. Finalement, dans le régime de « shell-tunneling », les phonons optiques apparaissent dans le spectre tunnel inélastique d2I/dV2. Dans le cinquième chapitre, je présente une étude du spectre tunnel de QDs HgSe. En appliquant une tension de grille, différents niveaux d’occupation du QD peuvent être atteints. La valeur de la bande interdite change avec le niveau d’occupation. Une valeur de 0.9 eV est observée pour l’inter-bande (QD vide), une valeur de 0.2 eV est observée pour l’intra-bande (QD occupé par 2 e). Sous illumination, un photocourant peut être mesuré en utilisant une technique de démodulation. De cette mesure, une durée de vide τ ~ 65 μs est extraite pour la paire électron-trou photo-générée. / My PhD work consists in a study of single Quantum Dot (QD) tunnel junctions. Following the introduction chapter, the second chapter will present the fundamental concepts needed to describe a single QD junction, such as quantum confinement and Coulomb blockade. In the third chapter, I will describe the sample fabrication methods and the measurement setups. In the fourth chapter, I will describe a tunneling spectroscopy study of single PbS QDs. Three distinct signatures of strong electron-phonon coupling are observed in the Electron Tunneling Spectrum (ETS) of these QDs. In the shell-filling regime, the 8 times degeneracy of the electronic levels is lifted by the Coulomb interactions and allows the observation of phonon sub-bands that result from the emission of optical phonons. At low bias, a gap is observed in the spectrum that cannot be closed with the gate voltage, which is a distinguishing feature of the Franck-Condon blockade. From the data, a Huang-Rhys factor in the range S~ 1.7 - 2.5 is obtained. Finally, in the shell tunneling regime, the optical phonons appear in the inelastic ETS d2I/dV2. In the fifth chapter, I present a tunnel spectroscopy study of single HgSe QDs. Upon tuning the gate voltage, different occupation levels of the QD can be reached. The gap observed in the ETS changes with the occupation level. A large inter-band gap, 0.9~eV, is observed for the empty QDs, and an intra-band gap 0.2~eV is observed for the doubly occupied QD. Upon illuminating the QD, a photocurrent can be measured using an especially designed demodulation technique. From this measurement, the lifetime τ ~65 μs is extracted for the photogenerated electron-hole in the QD.

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This thesis studies lead suphide (PbS) colloidal quantum dots and their photovoltaic applications. Different sizes of PbS QDs were synthesised and characterised using absorption spectroscopy and transmission electron microscopes. PbS QD Schottky junction devices were fabricated with AM1.5 power conversion efficiency up to 1.8 %. The Schottky junction geometry limits the device performance. A semiconductor heterojunction using ZnO as an electron acceptor was built and the device efficiency increased to 3%. By studying the light absorption and charge extraction profile of the bilayer device, the absorber layer has a charge extraction dead zone which is beyond the reach of the built-in electric field. Therefore, strategies to create a QD bulk heterojunction were considered to address this issue by distributing the junction interface throughout the absorber layer. However, the charge separation mechanism of the QD heterojunction is not clearly understood: whether it operates as an excitonic or a depleted p-n junction, as the junction operating mechanism determines the scale of phase separation in the bulk morphology. This study shows a transitional behaviour of the PbS/ZnO heterojunction from excitonic to depletion by increasing the doping density of ZnO. To utilise the excitonic mechanism, a PbS/ZnO nanocrystal bulk heterojunction was created by blending the two nanocrystals in solution such that a large interface between the two materials could facilitate fast exciton dissociation. However, the devices show poor performance due to a coarse morphology and formation of germinate pairs. To create a bulk heterojunction where a built-in electric field could assist the charge separation, a TiO₂ porous structure with the pore size matching with the depletion width was fabricated and successfully in-filled by PbS QDs. The porous device produces 5.7% power conversion efficiency, among one of the highest in literature. The enhancement comes from increased light absorption and suppression of charge recombination.