Dissertations / Theses on the topic 'D56 2009'

L'objectif principal de cette recherche consiste à identifier et à comparer les perceptions, les valeurs socioculturelles et les attitudes qui entrent en jeu dans le phénomène entrepreneurial en Guinée. Les valeurs modèlent la mentalité de l'entrepreneur, fondent ses activités et leur confèrent une signification et une légitimité. La recherche vise à déterminer celles qui poussent telle ou telle personne éduquée des milieux guinéens peul et soussou à s'adonner à des activités entrepreneuriales. La recherche privilégie une méthodologie mixte : quantitative, qualitative et comparative.
L'objectif principal de cette recherche consiste à identifier et à comparer les perceptions, les valeurs socioculturelles et les attitudes qui entrent en jeu dans le phénomène entrepreneurial en Guinée. Les valeurs modèlent la mentalité de l'entrepreneur, fondent ses activités et leur confèrent une signification et une légitimité. La recherche vise à déterminer celles qui poussent telle ou telle personne éduquée des milieux guinéens peul et soussou à s'adonner à des activités entrepreneuriales. La recherche privilégie une méthodologie mixte : quantitative, qualitative et comparative.
Elle s'appuie sur une recension documentaire relative aux valeurs socioculturelles des ethnies peule et soussou, un questionnaire et des entrevues qualitatives semi-structurées. Les données ont été recueillies auprès d'un échantillon d'entrepreneurs et de non-entrepreneurs issus des principales populations établies en Basse et Moyenne Guinée, tous volontaires et intéressés par la problématique visant à mieux comprendre la création d'entreprise au sein de ces ethnies. Les résultats présentés font état des caractéristiques des répondants et du rôle critique de leur milieu familial et ethnique, de leur entreprise, de leurs expériences entrepreneuriales, de leurs réseaux établis, de leurs valeurs et attitudes et de leurs perceptions de la création d'entreprise au sein de leur groupe d'appartenance.
Elle s'appuie sur une recension documentaire relative aux valeurs socioculturelles des ethnies peule et soussou, un questionnaire et des entrevues qualitatives semi-structurées. Les données ont été recueillies auprès d'un échantillon d'entrepreneurs et de non-entrepreneurs issus des principales populations établies en Basse et Moyenne Guinée, tous volontaires et intéressés par la problématique visant à mieux comprendre la création d'entreprise au sein de ces ethnies. Les résultats présentés font état des caractéristiques des répondants et du rôle critique de leur milieu familial et ethnique, de leur entreprise, de leurs expériences entrepreneuriales, de leurs réseaux établis, de leurs valeurs et attitudes et de leurs perceptions de la création d'entreprise au sein de leur groupe d'appartenance.
Les facteurs socioculturels identifiés associés à l'entrepreneuriat ethnique sont : le degré d'individualisme et de collectivisme au sein de l'ethnie, le degré de masculinité ou de féminité, le niveau de compétition au sein de la fratrie, le niveau de scolarité, la pratique du maraboutisme, l'importance du concept de baraka, l'existence des réseaux de relation, le statut et le revenu des futurs entrepreneurs, et le recours aux sources personnelles et familiales de financement de l'entreprise. Ainsi, l'interaction complexe de ces différents facteurs peut favoriser ou gêner l'émergence des entreprises.
Les facteurs socioculturels identifiés associés à l'entrepreneuriat ethnique sont : le degré d'individualisme et de collectivisme au sein de l'ethnie, le degré de masculinité ou de féminité, le niveau de compétition au sein de la fratrie, le niveau de scolarité, la pratique du maraboutisme, l'importance du concept de baraka, l'existence des réseaux de relation, le statut et le revenu des futurs entrepreneurs, et le recours aux sources personnelles et familiales de financement de l'entreprise. Ainsi, l'interaction complexe de ces différents facteurs peut favoriser ou gêner l'émergence des entreprises.
À la fois expression d'une culture et réaction à une situation de pauvreté, la création d'entreprise apparaît autant comme un choix délibéré pour certaines personnes que comme un passage obligé pour d'autres, qui n'ont pas une autre façon de s'en sortir. Le contexte historique et l'organisation familiale et sociale semblent expliquer le fait qu'il se crée plus d'entreprises au sein de l'ethnie peule que dans l'ethnie soussou. Mots clés : Facteurs socioculturels, création d'entreprise, entrepreneuriat, ethnie, culture, fratrie, baraka, Peul, Soussou, Guinée, Afrique.
À la fois expression d'une culture et réaction à une situation de pauvreté, la création d'entreprise apparaît autant comme un choix délibéré pour certaines personnes que comme un passage obligé pour d'autres, qui n'ont pas une autre façon de s'en sortir. Le contexte historique et l'organisation familiale et sociale semblent expliquer le fait qu'il se crée plus d'entreprises au sein de l'ethnie peule que dans l'ethnie soussou. Mots clés : Facteurs socioculturels, création d'entreprise, entrepreneuriat, ethnie, culture, fratrie, baraka, Peul, Soussou, Guinée, Afrique.

Neste trabalho é proposta a obtenção de filmes de silício aderentes às superfícies de substratos de aço-ferramenta AISI D6 e a caracterização de suas superfícies e interface filme-substrato. Os filmes de silício foram depositados nas superfícies polidas dos substratos metálicos por deposição física via fase vapor com vaporização do silício por feixe de elétrons (EB-PVD - Electron beam vaporization - Physical vapor deposition). Estes filmes foram depositados com espessuras pré-estabelecidas de aproximadamente 20, 100 e 500 nm, na temperatura de 200 oC. As superfícies dos filmes foram caracterizadas por microscopia eletrônica de varredura (MEV), para a análise da morfologia estrutural; por espectrometria por energia dispersiva de raios X (EDX), para a análise química semi-quantitativa; por difração de raios X (DRX), para a identificação de compostos cristalinos; por microscopia de força atômica (AFM - Atomic force microscopy), para a análise topográfica superficial (rugosidade) e espectroscopia Raman (RS - Raman spectroscopy), para análise das tensões residuais nos conjuntos filme-substrato. Os filmes e as interfaces filme-substrato foram analisadas por espectrometria de elétrons Auger (AES - Auger electron spectroscopy), em relação à variação da concentração atômica de silício. Os resultado das análises por MEV e AFM mostraram que os filmes depositados são nanoestruturados (espessuras de » 20 e 100nm) e microestruturados (espessura de 500 mm). As análises por AES mostraram que as espessuras dos filmes e das interfaces são proporcionais aos tempos de deposição. Os filmes depositados na temperatura de 200 oC mostraram a formação de interfaces diluídas por difusão atômica de silício substitucional termicamente ativada na estrutura cristalina do aço. No entanto, os resultados obtidos a partir das análises por espalhamento Raman para as tensões residuais determinadas, para este sistema filme-substrato, não são satisfatórios, provavelmente devido às anisotropias química e estrutural dos filmes e dos substratos. Os resultados indicaram as vantagens e as limitações das técnicas utilizadas para a caracterização destas superfícies e das interfaces filme-substrato.
In this work it is proposed to obtain the silicon thin films adherent on surfaces of tool-steel AISI D6 substrates and the characterization of films, substrate and film-substrate interfaces. Silicon thin films were deposited on polished surfaces of the metallic substrates by physical vapor deposition from the vaporization of silicon by electron beam technique (EB-PVD). These films were deposited with established thickness values of approximately 20, 100 e 500 nm, at 200° C. Film surfaces were characterized by scanning electron microscopy (SEM) to analyze the structural morphologies; by energy dispersive X-ray (EDS) to identify the chemical elements; by X-ray diffraction (XRD) to identify de crystalline chemical compounds; by atomic force microscopy (AFM) to scan the surface morphologies (surface roughness); and by Raman spectroscopy (RS) to analyze the residual surface stresses in the film-substrate assemblies. Film-substrate interfaces were analyzed by Auger electron spectroscopy (AES) to obtain the atomic silicon concentration profile. The results obtained from SEM and AFM analyzes showed that the deposited films presented structures in the nanometric (thickness of @ 20 and 100 nm) and micrometric (thickness of 500 nm) ranges. Films deposited at 200 °C showed the formation of diluted interfaces due to the thermal activated diffusion of silicon atoms, whose the thickness were proportional to the deposition time. However, the results obtained from the Raman spectroscopy analyses of the residual stress of the film-substrate assemblies are not satisfactory. These results are related to the chemical non-homogeneity and structural anisotropy of the films, interfaces and substrates. The results indicate some advantages and limits related to the techniques used for the characterization of the surfaces and the film-substrate interfaces.

Thesis (M.S. in Systems Engineering Management)--Naval Postgraduate School, September 2008.
Thesis Advisor(s): Osmundson, John "September 2008." Description based on title screen as viewed on November 4, 2008. Includes bibliographical references (p. 47-48). Also available in print.

Three very different approaches to understanding developmental biology were taken in this project. The first was an attempt to investigate the subcellular localisation of the Drosophila RhoGEF Pebble (Pbl) in live cells in real time, with an aim to further elucidate the role of Pbl in EMT and mesoderm migration in the embryo. This method, tetracysteine labelling, makes use of a 6 aa tag and a fluorescent, cell permeable, biarsenical ligand. Pioneered in Roger Tsien's laboratory, it utilises the reversible covalent bonds that form between closely spaced pairs of thiols in the tag and arsenical compounds. However, it was unsuccessful in allowing precise localisation of the Pbl protein either in vitro in Drosophila S2 cell culture or in vivo in wholemount embryos. While the approach has had success in the mammalian system, particularly mammalian cell culture, it would appear as though wholemount Drosophila embryos are not amenable to this technology. Secondly, I attempted to delete the PH domain of Pbl using ends out targeted homologous recombination, with an aim to investigate the role of the PH domain in EMT and mesoderm migration in the embryo. The first targeting attempt, to introduce a selectable marker, was successful, with a targeting efficiency of 1 in 160,000. However, the insertion of the PH deletion proved unsuccessful, perhaps due to a small recombination loophole introduced in the first targeting event. Thirdly and finally the development of the binucleate accessory glands was investigated and found to result from a failure of cytokinesis following mitoses that took place between 60 hours and 74 hours after puparium formation. In order to develop tools for the genetic manipulation of this tissue, the expression pattern of two GAL4 drivers, btlGAL4 and prdmf9GAL4, was investigated. prdmf9GAL4 was found to be expressed highly and consistently throughout the binucleate cell formation period and into the adult gland. Whereas, btlGAL4 was more highly expressed in the associated tracheal tissue of the gland during accessory gland development than in the gland itself. Expression of GAL4 by both drivers induced the formation of mononucleate accessory gland cells at different developmental stages, although the reason for this was not elucidated. This mononucleate cell type persisted in some cells of the adult gland in the case of prdmf9GAL4, but were not present in the adult gland in the case of btIGAL4. prdmf9GAL4 presents a potentially useful GAL4 driver for further investigations of the binucleate cell formation in the accessory glands.

The aim of this thesis is to explore how adults affected by the 2003 Canberra bushfires and adults affected by the 2004 tsunami in Aceh perceived and made meaning of their live experiences of dealing with the respective disasters, 5 to 6 years following the acute disaster impact. Semi-structured interviews were conducted with 25 and 29 participants in Canberra and Aceh respectively. The transcripts were analysed using an iterative process of constant comparison that built upon grounded theory method to identify core concepts across the two settings and developed an overarching framework. The research emphasises a dynamic interplay between people's circumstances and how their responses, which is presented using the metaphor of "riding the waves". Reflecting upon central elements expressed by participants, the "waves" pertained to the ebb and flow of threat and support, challenges and opportunities. The framework depicts external aspects as simultaneously demanding and moving a person to do things they may never otherwise see themselves doing. The study identified the following core concepts across the two disasters under the overarching metaphor of "riding the waves": the experience of being propelled (or struck) by extraordinary circumstances, which may result in extraordinary responses, referred to as "rising with the waves"; the experience of "just keep going" and "go with the flow" in order to "stay afloat" in such circumstances; the experience of "going into the depths" due to the gravity of the situation, where people feel the loss and letting reality "sink in" as well as try to uplift themselves by finding aspects of life that give them comfort and finding or creating a deeper sense of meaning. In addition, all of these were experienced in relation to, and together with, other people, through complex and dynamic interactions and connectedness. This thesis contributes by identifying core concepts and conceptualising a cohesive overarching framework that connects two very different socio-cultural and disaster contexts. The use of embodied metaphor allows a common language to convey experiences in a way that transcends linguistic and cultural conceptualisations and creates a mutual understanding based on our shared human nature. This research extends current conceptualisations of what happens to people affected by disasters. Some conceptual metaphors that have been used to describe people's experiences include "trauma", "resilience", and "growth". The concept of "riding the waves" spans from people's reactions during the acute incoming threat through to subsequent years. The image of the "waves" portrayed the size and the dynamic unpredictability of the external circumstances of disaster, while at the same time placed agency in people who navigate their circumstances. Without denying the adverse impacts of disasters, this research study highlights people's potential agency and capacity to respond in the face of uncontrollable forces.

Significant developments have been made in the field of C–H activation. However, various disadvantages, mainly low reactivity and selectivity, limit their usage in large-scale synthesis. It is crucial to understand the mechanisms and the nature of the transient species involved in the C–H activation paths to develop effective catalytic routes for homogeneous C–H functionalization reactions. Computational techniques are employed in this study to throw light on these processes. Chapter 1 briefly introduces C–H activation and functionalization reactions. After classifying the reactions on the basis of mechanisms, computational studies on the mechanisms of C–H activation reactions are described. The challenges involved in the discovery of efficient homogeneous C–H functionalization catalysts and progress made in the field are discussed. The insights provided to overcome the problems associated with the catalytic C–H functionalization reactions in a few examples are highlighted. In Chapter 2, DFT model studies are carried out to estimate the affinity and selectivity of 16-electron half-sandwich d6-metal fragments (η5–C5H5)Re(CO)2 and (η6–C6H6)W(CO)2 for binding with alkane C–H bonds. Different C–H binding sites of pentane, at the M06 level of theory have been evaluated. The effects of ancillary ligand variations on the metal–pentane binding strength are studied by substituting different ligands such as N-heterocyclic carbene (NHC), PF3 and NO+ for one of the carbonyl ligands. Isomers of the metal-pentane C–H σ-complexes studied in this chapter are shown in Scheme 1. Binding energies of the terminal methyl C–H bonds (C1 and C5) are significantly lower than those of the methylene C–H bonds (C2, C3 and C4) in all the cases. The metal–pentane binding interactions of the rhenium complexes are significantly stronger than those of the corresponding tungsten analogs. The PF3 complexes have slightly greater binding energies compared to the CO complexes, in both Re(I) and W(0) analogs. These results are in conformity with the experimental results. The electron-deficient nitrosyl complexes have the highest binding energies. These results illustrate that by proper tuning of the electronic factors of the transition-metal fragments with different ancillary ligands, the alkane C–H binding affinity can be controlled. Energy decomposition analyses (EDA) are carried out to determine the nature of the interaction between the metal fragments and pentane C–H bonds. Scheme 1. Formation of pentane C–H σ-complexes Chapter 3 addresses the energetics of various intramolecular site-exchange (chain walking) processes and C–H oxidative addition reactions (Scheme 2) of the pentane C–H σ-complexes studied in Chapter 2. Four possible site-exchange processes such as 1,2-, 1,3-, 1,4- and 1,5-migration processes are studied using DFT/M06 level of theory. η2-(H,H)···M type transition states are located for these migrations (Scheme 2). The 1,3-migration is the most favorable process. Two different pentyl hydride isomers, as shown in Scheme 2, are obtained for oxidative addition of methyl and methylene C–H bonds of pentane for all systems, at same level of theory. Oxidative insertion of metal into the methyl C–H bonds is more favorable than insertion into the methylene C–H bonds for all complexes. The activation energies of all site-exchange and C–H oxidative addition processes of the Re(I) complexes are significantly greater than those of the corresponding W(0) complexes. For all these processes, the activation barriers of the electron-deficient NO+ complexes are the greatest among all ligand systems studied, in both Re(I) and W(0) systems. These results are consistent with the experimental results and suggest that the experimentally observed pentyl hydride isomer [(η5–C5H5)Re(CO)(PF3)H(C5H11)] might be Isomer B and not Isomer A (Scheme 2). The C–H oxidative addition reactions are less favorable than dynamic site-exchange processes in all complexes. These results imply that the metal fragments migrate along the pentane chain more easily than insert into the pentane C–H bonds. Scheme 2. Alkane chain walking and C–H oxidative addition reactions Chapter 4 deals with the mechanisms and energetics of a unique metal migration process of an olefin complex that proceeds via olefinic (C–H)···Metal interaction. Migration of the Re(I) fragment from one π face of the olefin to the opposite π face in [(η5–C5H5)Re(NO)(PPh3)(PhCH═CH2)]+ has been documented experimentally by Gladysz and coworkers. The experimental results provide evidences for an intramolecular mechanism for this process (i.e., without styrene dissociation from Re(I)) and based on kinetic isotope effects (KIE), the involvement of a trans C–H bond is indicated. Either oxidative addition or a vinylic (C–H)···Re interaction could account for the experimentally observed kinetic isotope effect. In this study, the free energy of activation for the migration of Re from one enantioface of the olefin to the other through various pathways is computed using DFT calculations at the B3LYP and M06 levels. Two pathways, one that involves migration of Re through a trans (C–H)···Re interaction and another that involves oxidative addition of Re into the trans C–H bond, are identified as possible paths (Scheme 3) at the B3LYP level. Surprisingly, at the M06 level, DFT computes a lower energy path for the conducted tour mechanism that is not consistent with the experimental KIE. But the computed energy profiles for the reaction are consistent with the experiment when computations are carried out at the B3LYP level. Scheme 3. Mechanisms of olefin π face exchange reaction In Chapter 5, the mechanistic studies of C–H metathesis of d6 half-sandwich complex [(η5–C5Me5)Ru(CH3)(CO)(C6H6)] are discussed. A 1-step mechanism that proceeds via a four-center transition state and a 2-step Oxidative Addition and Reductive Coupling mechanism (OA/RC) are identified as possible mechanisms (Scheme 4) using DFT/M06 level of theory. The 1-step mechanism is more favorable than the 2-step mechanism. As in the oxidative addition intermediate, metal–hydrogen bond is observed in the four-center transition state of the 1-step mechanism. This mechanism is referred to as Oxidative Hydrogen Migration (OHM) rather than σ-Bond Metathesis (σ-BM) which proceeds via a transition state without M−H bonding. The effects of metal (M = Fe(II), Ru(II) or Os(II)) and ancillary ligand (L = H–, NHC, CO or NO+) variations on the mechanisms and energetics of the model Cp complex [(η5–C5H5)M(CH3)(L)(C6H6)] are also studied (Scheme 4). Scheme 4. Oxidative hydrogen migration vs Oxidative addition/reductive coupling Increase in the electron-density on the metal center, using electron-donating ligands such as H−, favors the formation of the oxidative species (intermediate or transition state) and reduces the activation barriers of the C–H metathesis reaction. Similarly, the electron-withdrawing NO+ ligand, which reduces the electron density on the metal center, increases the activation energies of the C–H metathesis reaction or disfavors the formation of the oxidative species. Factor affecting the choice of the mechanism of the C–H metathesis reaction is found to be the net charge transfer between the two fragments [(η5–C5H5)M(CH3)(L)] and benzene in [(η5–C5H5)M(CH3)(L)(C6H6)]. The computational studies reported in this thesis provide valuable insight into the mechanisms and energetics of C–H binding, activation and fluxional processes of the (C–H)···Metal σ alkane and alkene complexes. These studies will be helpful in solving problems associated with the C–H activation reactions. Reference Thenraj, M.; Samuelson, A. G. Organometallics 2013, 32, 7141. (For structural formula and figures pl see the abstract pdf file.)

Significant developments have been made in the field of C–H activation. However, various disadvantages, mainly low reactivity and selectivity, limit their usage in large-scale synthesis. It is crucial to understand the mechanisms and the nature of the transient species involved in the C–H activation paths to develop effective catalytic routes for homogeneous C–H functionalization reactions. Computational techniques are employed in this study to throw light on these processes. Chapter 1 briefly introduces C–H activation and functionalization reactions. After classifying the reactions on the basis of mechanisms, computational studies on the mechanisms of C–H activation reactions are described. The challenges involved in the discovery of efficient homogeneous C–H functionalization catalysts and progress made in the field are discussed. The insights provided to overcome the problems associated with the catalytic C–H functionalization reactions in a few examples are highlighted. In Chapter 2, DFT model studies are carried out to estimate the affinity and selectivity of 16-electron half-sandwich d6-metal fragments (η5–C5H5)Re(CO)2 and (η6–C6H6)W(CO)2 for binding with alkane C–H bonds. Different C–H binding sites of pentane, at the M06 level of theory have been evaluated. The effects of ancillary ligand variations on the metal–pentane binding strength are studied by substituting different ligands such as N-heterocyclic carbene (NHC), PF3 and NO+ for one of the carbonyl ligands. Isomers of the metal-pentane C–H σ-complexes studied in this chapter are shown in Scheme 1. Binding energies of the terminal methyl C–H bonds (C1 and C5) are significantly lower than those of the methylene C–H bonds (C2, C3 and C4) in all the cases. The metal–pentane binding interactions of the rhenium complexes are significantly stronger than those of the corresponding tungsten analogs. The PF3 complexes have slightly greater binding energies compared to the CO complexes, in both Re(I) and W(0) analogs. These results are in conformity with the experimental results. The electron-deficient nitrosyl complexes have the highest binding energies. These results illustrate that by proper tuning of the electronic factors of the transition-metal fragments with different ancillary ligands, the alkane C–H binding affinity can be controlled. Energy decomposition analyses (EDA) are carried out to determine the nature of the interaction between the metal fragments and pentane C–H bonds. Scheme 1. Formation of pentane C–H σ-complexes Chapter 3 addresses the energetics of various intramolecular site-exchange (chain walking) processes and C–H oxidative addition reactions (Scheme 2) of the pentane C–H σ-complexes studied in Chapter 2. Four possible site-exchange processes such as 1,2-, 1,3-, 1,4- and 1,5-migration processes are studied using DFT/M06 level of theory. η2-(H,H)···M type transition states are located for these migrations (Scheme 2). The 1,3-migration is the most favorable process. Two different pentyl hydride isomers, as shown in Scheme 2, are obtained for oxidative addition of methyl and methylene C–H bonds of pentane for all systems, at same level of theory. Oxidative insertion of metal into the methyl C–H bonds is more favorable than insertion into the methylene C–H bonds for all complexes. The activation energies of all site-exchange and C–H oxidative addition processes of the Re(I) complexes are significantly greater than those of the corresponding W(0) complexes. For all these processes, the activation barriers of the electron-deficient NO+ complexes are the greatest among all ligand systems studied, in both Re(I) and W(0) systems. These results are consistent with the experimental results and suggest that the experimentally observed pentyl hydride isomer [(η5–C5H5)Re(CO)(PF3)H(C5H11)] might be Isomer B and not Isomer A (Scheme 2). The C–H oxidative addition reactions are less favorable than dynamic site-exchange processes in all complexes. These results imply that the metal fragments migrate along the pentane chain more easily than insert into the pentane C–H bonds. Scheme 2. Alkane chain walking and C–H oxidative addition reactions Chapter 4 deals with the mechanisms and energetics of a unique metal migration process of an olefin complex that proceeds via olefinic (C–H)···Metal interaction. Migration of the Re(I) fragment from one π face of the olefin to the opposite π face in [(η5–C5H5)Re(NO)(PPh3)(PhCH═CH2)]+ has been documented experimentally by Gladysz and coworkers. The experimental results provide evidences for an intramolecular mechanism for this process (i.e., without styrene dissociation from Re(I)) and based on kinetic isotope effects (KIE), the involvement of a trans C–H bond is indicated. Either oxidative addition or a vinylic (C–H)···Re interaction could account for the experimentally observed kinetic isotope effect. In this study, the free energy of activation for the migration of Re from one enantioface of the olefin to the other through various pathways is computed using DFT calculations at the B3LYP and M06 levels. Two pathways, one that involves migration of Re through a trans (C–H)···Re interaction and another that involves oxidative addition of Re into the trans C–H bond, are identified as possible paths (Scheme 3) at the B3LYP level. Surprisingly, at the M06 level, DFT computes a lower energy path for the conducted tour mechanism that is not consistent with the experimental KIE. But the computed energy profiles for the reaction are consistent with the experiment when computations are carried out at the B3LYP level. Scheme 3. Mechanisms of olefin π face exchange reaction In Chapter 5, the mechanistic studies of C–H metathesis of d6 half-sandwich complex [(η5–C5Me5)Ru(CH3)(CO)(C6H6)] are discussed. A 1-step mechanism that proceeds via a four-center transition state and a 2-step Oxidative Addition and Reductive Coupling mechanism (OA/RC) are identified as possible mechanisms (Scheme 4) using DFT/M06 level of theory. The 1-step mechanism is more favorable than the 2-step mechanism. As in the oxidative addition intermediate, metal–hydrogen bond is observed in the four-center transition state of the 1-step mechanism. This mechanism is referred to as Oxidative Hydrogen Migration (OHM) rather than σ-Bond Metathesis (σ-BM) which proceeds via a transition state without M−H bonding. The effects of metal (M = Fe(II), Ru(II) or Os(II)) and ancillary ligand (L = H–, NHC, CO or NO+) variations on the mechanisms and energetics of the model Cp complex [(η5–C5H5)M(CH3)(L)(C6H6)] are also studied (Scheme 4). Scheme 4. Oxidative hydrogen migration vs Oxidative addition/reductive coupling Increase in the electron-density on the metal center, using electron-donating ligands such as H−, favors the formation of the oxidative species (intermediate or transition state) and reduces the activation barriers of the C–H metathesis reaction. Similarly, the electron-withdrawing NO+ ligand, which reduces the electron density on the metal center, increases the activation energies of the C–H metathesis reaction or disfavors the formation of the oxidative species. Factor affecting the choice of the mechanism of the C–H metathesis reaction is found to be the net charge transfer between the two fragments [(η5–C5H5)M(CH3)(L)] and benzene in [(η5–C5H5)M(CH3)(L)(C6H6)]. The computational studies reported in this thesis provide valuable insight into the mechanisms and energetics of C–H binding, activation and fluxional processes of the (C–H)···Metal σ alkane and alkene complexes. These studies will be helpful in solving problems associated with the C–H activation reactions. Reference Thenraj, M.; Samuelson, A. G. Organometallics 2013, 32, 7141. (For structural formula and figures pl see the abstract pdf file.)

This thesis explores the use of the border in governing on the China-Laos frontier. By focusing on the notion of ‘frontier’, the thesis breaks with views of border regions as sites of anomie and state avoidance. It presents the frontier not simply as a field of confrontation between state and society but instead, as a “middle ground” (White 1991), a socio-economic and cultural space where the practices of peripheral subjects intersect with central powers, producing heterogeneous scenarios of manoeuvring, negotiation, collaboration, and resistance. By embracing a view of power as simultaneously totalising and individualising, the thesis also stresses the ongoing significance of the nation-state as a regulatory agent of human, capital and goods mobility across borders. It questions the dissolution of borders suggested by some globalisation theories and highlights the current paradox of the simultaneous reinforcement of state authority and the re-opening of international borders in mainland Southeast Asia. It argues that the practices enacted by border dwellers are not to be attributed to a waning of state power on the periphery due to the inroads of globalisation. Rather, they are the product of an ongoing governing pattern of “experimentation under hierarchy” (Heilmann 2008). This is a mechanism whereby the margins are allowed to experiment autonomously under the scrutiny of the Lao and Chinese centres. In this sense, local experimentation flourishes like ‘roses’. When these bloom into a centrifugal vortex, they are contained by an authoritarian backlash which, in extreme cases, resorts to ‘rifles’. Through a historical account and four contemporary ethnographic case studies, the thesis critically interrogates four main themes raised in the literature on theories of globalisation: “graduated sovereignty” (Ong 1999, 2000), unconstrained cross-border mobility, crossborder ethnic re-connectedness, and marginal resistance to the centre of power. First, an analysis of Chinese-driven rubber investments in north-western Laos demonstrates that the circulation of capital across the borders does not translate into an anomalous variegation of sovereignty. The historical account suggests that graduation in sovereignty is a governing model which, despite many changes from pre-colonial, to colonial and post-colonial times, has been variously applied throughout history by the major political entities in the Upper Mekong region. A second case study argues that the socio-economic initiatives of ethnic Akha villagers in Laos across the border are not an effect of “zomia” (Scott 2008, forthcoming; van Schendel 2002), a mechanism whereby unruly peripheral subjects repel central power. They are an expression of an incomplete process of modem state formation and the remnants of pre-colonial patterns of governing. A third case study examines how the notion of belonging among a group of Tai youth in a border village in China is not articulated through a trans-frontier pan-ethnic sentiment of resistance to centralising policies. Rather, it is expressed through social and cultural identification with the Chinese government’s agenda of development and modernisation. A final case study argues that the struggles of a group of Tai traders to assert themselves as “flexible citizens” (Ong 1999) of the frontier demonstrate that mobility of subjects and objects across the border remains constrained by the structuring system of the state, despite the claims of regional economic integration. Therefore, in contrast with the fluidity of the ‘frontier’, the ‘border’ continues to maintain its binding significance and remains the focal point of state regulation.