Nous avons développé un système de transfert des surfaces monocristallines préparées sous ultra-haut vide (UHV) vers un milieu électrolytique pour effectuer des mesures voltampérométriques. Ce système original très compact comprend une valise sous vide et une cellule électrochimique dédiée. Le système a été testé avec succès sur des surfaces monocristallines de platine, en particulier la surface Pt(111) très sensible à la qualité de la préparation sous UHV. Puis nous avons utilisé ce système pour caractériser les propriétés électrochimiques du système Pt/W(111) avec d'une part l'effet des contraintes élastiques pour les couches ultra-minces planaires de Pt épitaxié ainsi que la stabilité en milieu électrolytique de nano-pyramides obtenues par déstabilisation en température des surfaces Pt/W(111). Ce travail ouvre des perspectives intéressantes pour l'étude électrochimiques des surfaces modèles préparées sous UHV. / In this work, we developed a system for transferring single crystal surfaces prepared in ultra-high vacuum (UHV) to an electrolytic medium where voltammetric measurements are carried out. This unique system includes a compact vacuum chamber and its dedicated electrochemical cell. The system was successfully tested on platinum single-crystal surfaces; in particular the Pt (111) surface which is well known for it's sensitive to the quality of the preparation under UHV. Then we used this system for characterizing the electrochemical properties of the Pt / W (111) system, both the effect of elastic strain of ultrathin epitaxial planar Pt films and the stability of nano-pyramids obtained after a temperature annealing of the planar Pt / W (111) system. This work opens up interesting perspectives for the study of electrochemical model surfaces prepared in UHV.

Fear of missing out (FoMO) is a type of internet slang used to describe the “pervasive apprehension that others might be having rewarding experiences from which one is absent” (Przybylski, Murayama, DeHaan & Gladwell, 2013, p. 1841). This pervasive fear encompasses an individual’s life and it is exacerbated by the social media updates of online counterparts. A study conducted by a South African pharmaceutical company revealed that 62% of the respondents have a constant fear of missing out on something that might be happening elsewhere. This study underscores the relevance of studying FoMO as a construct in the South African context. The current study aims to investigate the relationship between FoMO and satisfaction with life, as these two constructs have previously shown to be negatively correlated. The self-proclaimed FoMO sufferers who will be partaking in this study will be requested to complete an online questionnaire to establish the nature of the relationship between FoMO and satisfaction with life. / Psychology / M.A. (Clinical Psychology)

We firstly numerically recalculate the Ricci tensor of non-stationary axisymmetric space-times (originally calculated by Chandrasekhar) and we find some discrepancies both in the linear and non-linear terms. However, these discrepancies do not affect the results concerning linear perturbations of a Schwarzschild black hole. Secondly, we use these Ricci tensors to derive the Zerilli and Regge-Wheeler equations and use the Newman-Penrose formalism to derive the Bardeen-Press equation. We show the relation between these equations because they describe the same linear perturbations of a Schwarzschild black hole. Thirdly, we illustrate heuristically (when the angular momentum (l) is 2) the relation between the linearized solution of the Einstein vacuum equations obtained from the Bondi-Sachs metric and the Zerilli equation, because they describe the same linear perturbations of a Schwarzschild black hole. Lastly, by means of a coordinate transformation, we extend Chandrasekhar's results on linear perturbations of a Schwarzschild black hole to the Bondi-Sachs framework. / Mathematical Sciences / M. Sc. (Applied Mathematics)

Between 1980-2006, thousands of South African pension funds converted members from defined benefit to defined contribution structures. This research set out to answer the questions of why this phenomenon occurred and whether peculiar environmental circumstances influenced the outcome. The research framework identified various stakeholders in the retirement fund industry - government; regulator; pension fund adjudicator; ombudsman for long term insurance; trade unions; members; trustees; business; employers and service providers - and isolated the elements to be considered in the research. Industry experts were interviewed to obtain a macro view of the phenomenon and specific manifestations of the phenomenon were also considered in case studies. The purpose of the research was to develop a model for managers to assist them in dealing with environmental change. Qualitative research methodology was utilised and feedback from semi-structured interviews was categorised into several emergent themes. Within-case and cross-case analyses were conducted. Research results indicate that the conversion phenomenon occurred in two waves - one initiated in the 1980s and driven by the trade unions and a second in the 1990s, driven by employers, often at the advice of their consultants. Evidence of the start of a third wave also emerged. Results indicate that an environmental shock exerted a substantial influence on the course of events. Under these:  Various factors combined to drive organisational evolution (i.e. adaptation to the environment).  Adaptation speed was inappropriate and exceeded that which was required for sufficient thought.  Uncertainty and vacuum circumstances arose leading to consequences that require redress.  The power of the relative stakeholders changed and influenced the strategic outcome.  An imbalance in stakeholder interests arose and ethical factors became consequential.  Business acted to restore certainty for itself. Existing literature explained organisational behaviour in environments of competitive shock and high turbulence, but not in circumstances of environmental shock. A model emerged to assist managers to deal with environmental change, which was applied to an analysis of pension fund reform. It was also applied to the pension fund perspective on Broad-Based Black Economic Empowerment. This model may also be applied in analysis of land redistribution, sanctions and constitutional development. / Business Management / DBL

This thesis investigates the period in Judah which took place precisely a century between the death ofHezekiah (687 BCE) and the final fall of Jerusalem (587 BCE) Seldom has a nation experienced so many dramatically sudden reversals of fortune in so relatively short a time. Throughout the first half of the seventh century BCE the Assyrian empire reigned supreme. In the second half, in rapid succession, Judah, as a vassal, experienced periods of independence and of subjection, first to Egypt, then to Babylonia, before finally destroying herself in a futile rebellion against the latter. The aim of the thesis was to set Judah in the global context and investigate the role she played. To this end the Great Powers, namely Assyria, Egypt and Babylonia were surveyed, as well as were the Small Powers, like Judah, Phoenicia and the Transjordanian states, and the relationships probed. The thesis traces the life of the wicked but extraordinarily successful King Manasseh, and his equally reprobate son, Amon, who was brutally murdered by his servants, and was avenged by 'the people of the land'. Josiah is the only monarch who fits the Deuteronomistic requirements of a good king. Religious and national reform generally go hand in hand with politics, and the cultic reform and centralization of the cult characterise his reign. · With the fall of Assyria, the temporary surge into prominence by Egypt and the tragic death of Josiah in 609 BCE, Judah experienced radical political fluctuations and with them alternate subjugation by, and rebellion against, each of the major powers. Inexperienced leadership and a situation of dual kings, followed Josiah's death. The rapidly changing international scene demanded of the rulers of Judah skillful manoeuvring and exceptional adaptability, and frequently confronted them with ominous political situations. Judaean leaders and the puppet King Zedekiah, propped up by false prophets, failed to grasp the shift in the balance of power, and clung to questionable Egyptian aid against the new world power, Babylonia. Highly vulnerable and left in the lurch, Jerusalem faced protracted siege and famine in Jerusalem, destruction ofthe Temple, and deportation ofthe cream ofher people. / Classics and Modern European Languages / D. Litt. et Phil. (Judaica)

La spectroscopie EPES (Elastic Peak Electron Spectroscopy) permet de mesurer le pourcentage he d’électrons rétrodiffusés élastiquement par la surface d’un échantillon soumis à un bombardement électronique. C’est une méthode non destructive et extrêmement sensible à la surface. L'objectif de ce travail est de modéliser le cheminement des électrons élastiques dans la matière grâce à une simulation informatique basée sur la méthode Monte Carlo. Cette simulation contribue de manière essentielle à la connaissance et à l'interprétation des résultats expérimentaux obtenus par spectroscopie EPES. Nous avons, de plus, adapté cette simulation à différentes surfaces transformées à l’échelle micrométrique et nanométrique. A l’aide d’une méthode originale, basée sur une description couche par couche du matériau, j’ai réalisé un programme informatique (MC1) rendant compte du cheminement des électrons élastiques dans les différentes couches du matériau. Le nombre d’électrons ressortant de la surface dépend de nombreux paramètres comme : la nature du matériau à étudier, l’énergie des électrons incidents, l’angle d’incidence, les angles de collection des analyseurs. De plus, je me suis intéressé à l’effet de la rugosité de la surface et j’ai démontré qu’elle joue un rôle déterminant sur l’intensité du pic élastique. Ensuite, grâce à l’association de la spectroscopie EPES et de la simulation Monte Carlo, j’ai déduit les modes de croissance de l’or sur substrat d’argent et de cuivre. Les effets de l’arrangement atomique et des pertes énergétiques de surfaces ont ensuite été étudiés. Pour cela, une deuxième simulation MC2 tenant compte de ces deux paramètres a été réalisée permettant d’étudier les surfaces à l’échelle nanométriques. Ces paramètres jusqu’alors non pris en compte dans notre simulation MC1, joue un rôle essentiel sur l’intensité élastique. Ensuite, j’ai obtenu une formulation simple et exploitable pour l’interprétation des résultats obtenus par la simulation MC2 pour un analyseur RFA. Afin de valider, les différents résultats de la simulationMC2, j’ai réalisé des surfaces de silicium nanostructurées, à l’aide de masques d’oxyde d’alumine réalisés par voie électrochimique. J’ai pu créer des nano-pores par bombardement ionique sous ultravide sur des surfaces de silicium. Afin de contrôler la morphologie de la surface, j’ai effectué de l’imagerie MEB ex-situ. La simulation Monte Carlo développée associée aux résultats EPES expérimentaux permet d’estimer la profondeur, le diamètre et la morphologie des pores sans avoir recours à d’autres techniques ex-situ.Cette simulation MC2 permet de connaître la surface étudiée à l’échelle nanométrique. / EPES (Elastic Peak Electron Spectroscopy) allows measuring the percentage he of elastically backscattered electrons from the surface excited by an electron beam. This is a non destructive method which is very sensitive to the surface region. The aim of this work is to model the trajectory of elastic electrons in the matter with a computer simulation based on Monte Carlo method. This simulation allows interpreting experimental results of the EPES spectroscopy. We have moreover adapted this simulation for different surfaces transformed to micrometer and nanometer scales. Using an original method, based on a description of material layer by layer, I realized a computer program (MC1) that takes into account the path of elastic electrons in different layers of material. The number of electrons emerging from the surface depends on many parameters such as: the electron primary energy, the nature of the material, the incidence angle and the collection angles of the analyzer. In addition, I was interested in the effect of surface roughness and I showed that it plays an important role in the intensity of the elastic peak. Then, through an association of the EPES and the Monte Carlo simulation results, I deduced the growth patterns of gold on silver and copper substrates. The effects of the atomic arrangement and the surface excitations were then studied. For this, a new simulation MC2 that takes into account these two parameters has been developed to study nanoscale surfaces. These parameters not previously included in our MC1simulation play a important role in the elastic intensity. Then I have got a simple formula for interpreting the results obtained by the simulation for a RFA analyzer. To validate the different results of the simulation MC2, I realized nano-structured silicon surfaces, using aluminium oxide masks. Nano-pores have been created by Ar+ ions bombardment in UHV chamber on silicon surfaces.To control the morphology of the surfaces, I realized SEM images (Techinauv Casimir) ex-situ. The Monte Carlo simulations, developed here, associated with the EPES experimental results can estimate the depth, the diameter, the morphology of pores without the help of other ex-situ techniques.

Afin de pouvoir continuer la miniaturisation de la brique de base des circuits électroniques, le transistor MOS, l’introduction d’oxyde de grille à haute permittivité était inévitable. Un empilement de type high-k/grille métal en remplacement du couple SiO2 /Poly-Si est introduit afin de limiter le courant de fuite tout en conservant un bon contrôle électrostatique du canal de conduction. L’introduction de ces matériaux pose naturellement des questions de fiabilité des dispositifs obtenus et ce travail s’inscrit dans ce contexte. Afin de réaliser des mesures de durée de vie sans avoir à finir les dispositifs, une méthode utilisant le C-AFM sous ultravide est proposée. Le protocole expérimental repose sur une comparaison systématique des distributions des temps de claquage obtenues à l’échelle du composant et à l’échelle nanométrique. La comparaison systématique des mesures s’avère fiable si l’on considère une surface de contact entre la pointe et le diélectrique de l’ordre du nm². Des distributions de Weibull présentant une même pente et un même facteur d’accélération en tension sont rapportées montrant une origine commune pour le mécanisme de rupture aux deux échelles.Une résistance différentielle négative, précédant la rupture diélectrique, est rapportée lors de mesures courant–tension pour certaines conditions de rampe. Ce phénomène de dégradation de l’oxyde, visible grâce au C-AFM , est expliqué et modélisé dans ce manuscrit par la croissance d’un filament conducteur dans l’oxyde. Ce même modèle permet aussi de décrire la rupture diélectrique.Finalement, l’empilement de grille bicouche du noeud 28nm est étudié. Une preuve expérimentale montrant que la distribution du temps de claquage du bicouche est bien une fonction des caractéristiques de tenue en tension propres de chaque couche est présentée. / In order to continue the scaling of the MOS transistor the replacement of the gate oxide layer by a high K/Metal gate was mandatory. From a reliability point of view, the introduction of these new materials could cause a lifetime reduction. To test the lifetime of the device a new technique using the C-AFM under Ultra High Vacuum is proposed. The experimental approach is based on a systematic comparison between the time to failure distribution obtained at device scale and at nanoscale. The comparison is reliable if we assume a contact surface of several nm² under the tip. Weibull distributions with a same slope and a same voltage acceleration factor have been found exhibiting a common origin of breakdown at both scales.We have reported a negative differential resistance phenomenon during Current-Voltage measurements. This degradation phenomenon has been modelled and explained by the growth of a conductive filament in the oxide layer. This model is also able to describe the breakdown of the oxide layer.Finally the bi layer gate stack of the 28nm node was studied. The first experimental proof confirming that the lifetime distribution of the bi-layer gate stack is a function of the lifetime of each layer taken separately is presented.

System on Chip (SoC) and System in Package (SiP) are two electronic technologies that involve integrating multiple functionalities onto a single platform. When the platform is a single wafer, as in SOC, it requires the ability to deposit various materials that enable the different functions on to an underlying substrate that can host the electronic circuitry. Transition metal oxides which have a wide range of properties are ideal candidates for the functional material. Si wafer on which micro-electronics technology is widely commercialized is the ideal host platform. Integrating oxides with Si, generally in the form of thin films as required by microelectronics technology, is however a challenge. It starts with the fact that the properties of crystalline oxides to be exploited in performing various functions are direction dependent. Thus, thin films of these oxides need to be deposited on Si in certain crystallographic orientations. Even if a suitably oriented Si wafer surface were available, it does not always provide for epitaxial growth a critical requirement for controlling the crystalline orientation of thin films. This is because Si surface is covered by an amorphous oxide of Si (SiOx). Thus, during growth of the functional oxide, an ambience in which the Si itself will not oxidize needs to be provided. In addition, during thin film growth on either Si or SiOx surface stresses are generated from various sources. Stress and its relaxation are also associated with the formation and evolution of defects. Both, stress and defects need to be managed in order to harness their beneficial effects and prevent detrimental ones. Given the requirement of SoC technology and the problem associated, the research work reported in this thesis was hence concerned with the precise controlling the stress and microstructure in oxide thin films deposited on Si substrates. In order to do so a versatile, ultra high vacuum (UHV) thin film with a base pressure of 10-9 Torr was designed and built as part of this study. The chamber is capable of depositing films by both sputtering (RF & DC) and pulsed laser ablation (PLD). The system has been designed to include an optical curvature measurement tool that enabled real-time stress measurement during growth. Doped zirconia, ZrO2, was chosen as the first oxide to be deposited, as it is among the few oxides that is more stable than SiOx. It is hence used as a buffer layer. It is shown in this thesis that a change in the growth rate at nucleation can lead to (100) or (111) textured films. These two are among the most commonly preferred orientation. Following nucleation a change in growth rate does not affect orientation but affects stress. Thus, independent selection of texture and stress is demonstrated in YSZ thin films on Si. A quantitative model based on the adatom motion on the growth surface and the anisotropic growth rates of the two orientations is used to explain these observations. This study was then subsequent extended to the growth on platinized Si another commonly used Si platform.. A knowledge of the stress and microstructure tailoring in cubic zirconia on Si was then extended to look at the effect of stress on electrical properties of zirconia on germanium for high-k dielectric applications. Ge channels are expected to play a key role in next generation n-MOS technology. Development of high-k dielectrics for channel control is hence essential. Interesting stress and property relations were analyzed in ZrO2/Ge. Stress and texture in pulsed laser deposited (PLD) oxides on silicon and SrTiO3 were studied. It is shown in this thesis that stress tuning is critical to achieve the highest possible dielectric constant. The effect of stress on dielectric constant is due to two reasons. The first one is an indirect effect involving the effect of stress on phase stability. The second one is the direct effect involving interatomic distance. By stress control an equivalent oxide thickness (EOT) of 0.8 nm was achieved in sputter deposited ZrO2/Ge films at 5 nm thickness. This is among the best reported till date. Finally, the effect of growth parameters and deposition geometry on the microstructural and stress evolution during deposition of SrTiO3 on Si and BaTiO3 on SrTiO3 by pulsed laser deposition is the same chamber is described.

This thesis studies the interaction between the bare Cu{311} surface with NO and NH3,individually and co-adsorbed using reflection-absorption infrared spectroscopy (RAIRS). In addition to the bare Cu{311} surface, the interaction of NO and NH3 with the various oxygen phases of the Cu{311} surface phases was also studied. Several other techniques were used in tandem to support the study, such as low energy electron diffraction (LEED) and temperature programmed desorption (TPD) experiments using mass spectrometry. The study was carried out in pursuit an understanding of the underlying mechanism of the selective catalytic reduction (SCR) of NO using NH3 in current diesel engines. The dosing of NO onto the Cu{311} surface at 100 K leads to the initial adsorption of intact NO. After an exposure threshold is reached, individual NO molecules react with another NO molecule to form (NO)2 dimers. These dimer species subsequently form N2O, leaving O(a) on the surface. Oxygen was found to be an inhibitor for the reaction, either due to the reaction in a self-poisoning process or from oxygen pre-dosing onto the Cu{311} surface. Temperature plays a minor role with regards to NO/Cu{311}, as it only affects the amount of NO on the surface along with adsorbate surface mobility. Similarly, NH3 was found to adsorb intact onto the Cu{311} surface and not to react or dissociate at 100 K. Oxygen acts as a site blocker for the adsorption, but can also stabilise NH3 to remain on the surface at higher temperatures due to electronic effects. At 300 K, it was found that both the bare and oxygen pre-covered Cu{311} surface was able to dissociate NH3 into NH2. The co-adsorption of NO and that of NH3 onto the Cu{311} surface were found to be largely independent of each other and the interaction is dominated by the displacement of NO by NH3. However, as NO adsorption on the Cu{311} surface forms O(a), it indirectly affects the adsorption of NH3 by creating an oxygen covered Cu{311} surface, which changes how NH3 adsorbs onto the surface.

Submitted by Geandra Rodrigues (geandrar@gmail.com) on 2018-05-15T19:23:47Z No. of bitstreams: 1 tiberiodepaulanetto.pdf: 1926871 bytes, checksum: 17bceffda5c85de37a0d50a14f4f3f04 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2018-05-22T14:37:09Z (GMT) No. of bitstreams: 1 tiberiodepaulanetto.pdf: 1926871 bytes, checksum: 17bceffda5c85de37a0d50a14f4f3f04 (MD5) / Made available in DSpace on 2018-05-22T14:37:09Z (GMT). No. of bitstreams: 1 tiberiodepaulanetto.pdf: 1926871 bytes, checksum: 17bceffda5c85de37a0d50a14f4f3f04 (MD5) Previous issue date: 2017-02-22 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Nesta tese, exploram-se diferentes aspectos e aplicações das teorias gravitacionais com correções quânticas. O texto é dividido em três partes principais. Na primeira parte, são consideradas as soluções linearizadas em diferentes teorias de gravitação com derivadas superiores. O potencial Newtoniano é calculado nos modelos locais, super-renormalizáveis no nível quântico, e mostra-se que a singularidade Newtoniana é cancelada devido a contribuição dos modos massivos extras. Logo depois, o colapso gravitacional de uma pequena massa é estudado na gravitação não-local livre de fantasmas, sendo o principal resultado a ausência da singularidade na solução do campo gravitacional e a possibilidade da não formação do miniburaco negro como resultado do colapso. Na segunda parte, algumas questões sobre a inflação induzida pela anomalia conforme são estudadas. É discutida a possibilidade da transição entre os períodos de inflação estável para instável. É mostrado que esta transição é automática se as correções quânticas nesse período forem desprezadas. Em seguida, considera-se o efeito de termos que violam as simetrias de CPT e Lorentz na inflação induzida pela anomalia conforme. É demonstrado que os novos termos responsáveis por violar essas simetrias não afetam a dinâmica do fator de escala da métrica. Por fim, na terceira parte as correções quânticas para o modelo dos Galileons e para as teorias dos campos massivos tensoriais antissimétricos são obtidas. É mostrado que o propagador da teoria dos Galileons recebe correções quânticas com derivadas superiores e que o teorema de não-renormalização do modelo dos Galileons permanece, de uma maneira generalizada, válido na região das baixas energias. Depois, por meio de cálculos explícitos das correções quânticas semiclássicas não-locais é confirmada a equivalência quântica entre os modelos dos campos tensoriais antissimétricos massivos com a teoria de Proca e com o modelo do campo escalar massivo mínimo. / In this thesis, different aspects and applications of gravitational theories with quan-tum corrections are explored. The text is divided into three main parts. In the first part, the linearized solutions in different gravity theories with higher derivatives are considered. The Newtonian potential is calculated in the local models, super-renormalizable at the quantum level, and it is shown that the Newtonian singularity is cancelled due to the contributions of the extra massive modes. Then the gravitational collapse of a small mass is studied in non-local ghost-free gravity, being the main result the absence of singularity in the gravitational field solution and the possibility of non-mini black hole formation as the collapse result. In the second part, some issues about anomaly-induced inflation are studied. It is discussed the possibility of the transition between stable to unstable periods of inflation. It is shown that this transition is automatic if the quantum corrections in this period are neglected. In the following, we consider the effect of CPT and Lorentz-violating terms in the conformal anomaly-induced inflation. It is shown the new terms responsible to violate these symmetries do not affect the dynamics of the metric scale factor. Finally, in the third part, the quantum corrections for the Galileon model and for the theory of the massive antisymmetric tensor fields are obtained. It is shown that the propaga-tor of Galilean theory receives quantum corrections with higher derivatives and that the non-renormalization theorem for Galileon models remains, in a generalized way, valid in the low-energy region. Then, by means of explicit calculations of non-local semiclassical quantum corrections, the quantum equivalence between the massive antisymmetric tensor field models with the Proca theory and minimal massive scalar field model is confirmed.