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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
251

Effect of deformation on the broad and fine structure of the Isovector Giant Dipole Resonance in 142-150 Nd and 152 Sm

Donaldson, Lindsay Michelle January 2016 (has links)
A thesis submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Doctor of Philosophy. Johannesburg, 2016. / This study investigates the e ect of nuclear deformation on both the broad and ne structure of the Isovector Giant Dipole Resonance (IVGDR) in the rareearth region. The IVGDR is strongly excited at and close to zero degrees by virtual-photon Coulomb excitation. As such, the Zero-degree Facility of the K600 magnetic spectrometer of iThemba Laboratory for Accelerator Based Sciences (iThemba LABS) was used with an incident proton beam energy of 200 MeV to measure high energy-resolution (p,p0) scattering on a range of neodymium isotopes from spherical 142 60Nd82 to the permanently deformed 150 60Nd90 and the correspondingly deformed 152 62Sm90 in the region of the IVGDR. It is important to note that for nuclei with 88 N 92, a detailed study of the IVGDR is of speci c interest since it is here that a transition from spherical to permanently deformed nuclei occurs. An extensive data analysis procedure was performed, which included cross section extraction and conversion to equivalent photo-absorption spectra for comparison with existing photo-absorption data and theoretical predictions. For the more deformed 150Nd and 152Sm nuclei, however, the data from this study lack the expected double-peaked structure resulting from the splitting of the IVGDR into K = 0 and K = 1 components, and display a signi cant reduction in the strength of the K = 0 component of the IVGDR in comparison to previously published photo-absorption spectra. This reduced strength near the neutron threshold agrees very well with recent photo-neutron experiments. A ne structure analysis was performed on all of the measured isotopes, that is, 142;144;146;148;150Nd and 152Sm through the use of techniques associated with ii the continuous wavelet transform. Characteristic energy scales for the present high energy-resolution data are extracted using the complex Morlet motherwavelet and compared to those obtained for the theoretically predicted B(E1) strength functions. Finally, conclusions regarding the suitability of the model predictions to the current data are drawn. / GR 2016
252

Caractérisation du rôle de la O-N-acétyl-glucosaminylation dans la structuration sarcomérique du muscle squelettique et de son implication dans certaines pathologies musculaires / Characterization of the role of O-linked N-acetyl-glucosaminylation in the sarcomere structure of skeletal muscle, and its involvement in some muscular diseases

Lambert, Matthias 27 September 2016 (has links)
La structuration sarcomérique, essentielle au muscle squelettique, est remarquablement organisée par de nombreuses protéines myofilamentaires interagissant entre elles. Plusieurs de ces protéines sont modifiées par une glycosylation atypique, la O-N-acétyl-β-D-glucosaminylation (O-GlcNAcylation), similaire en certains aspects à la phosphorylation et connue pour être un modulateur de l’activité contractile. Cependant à ce jour, son rôle dans l’organisation sarcomérique n’a pas été caractérisé. Lors de cette thèse, des traitements pharmacologiques appliqués sur des myotubes C2C12 ont permis de moduler de manière sensible et dynamique le taux de O-GlcNAcylation du myofilament, associé à des changements de la morphométrie du sarcomère et à des remaniements de certains complexes protéiques incluant des protéines structurales clé du sarcomère. En particulier, l’interaction entre la desmine et son chaperon moléculaire, l’αB-cristalline, était modulée dépendamment de la O-GlcNAcylation dans un dialogue étroit et complexe avec la phosphorylation. De plus, certains sites de O-GlcNAcylation ont été localisés sur des protéines myofilamentaires telles que la desmine au niveau d’un site connu pour être muté dans les desminopathies, l’αB-cristalline dans un domaine d’interaction avec la desmine, et la titine où plusieurs sites ont été identifiés en cluster dans un domaine d’interaction essentiel. L’ensemble de ces résultats démontrent que la O-GlcNAcylation est impliquée dans la structure du sarcomère et de son interactome, et amènent de nouvelles données quant à la compréhension de la physiopathologie de certaines maladies musculaires caractérisées par une désorganisation du sarcomère. / The sarcomere structure, essential for skeletal muscle, is strikingly organized by several protein-protein interactions between myofilament proteins. Many of them are modified by an atypical glycosylation, the O-linked N-acetyl-glucosaminylation (O-GlcNAcylation), similar in some aspects to phosphorylation, and known to be a modulator of the contractile activity. However to date, its role in sarcomeric organization remains to be considered. In this Ph.D, some pharmacological treatments applied to C2C12 myotubes have modulated the global O-GlcNAc level of the myofilament-enriched fraction in a dynamic and sensitive manner, associated to changes of the sarcomeric morphometry and of some protein complexes including key structural proteins of the sarcomere. Notably, the interaction between desmin and its molecular chaperone, αB-crystallin, have been modulated depending on the O-GlcNAcylation within an extensive crosstalk and interplay with phosphorylation. Moreover, some O-GlcNAc sites have been located in myofilament proteins, such as desmin in a site known to be mutated in desminopathy, αB-crystallin within a desmin binding domain, and titin where some O-GlcNAc sites have been identified in cluster within an essential interaction domain. Taken together, the results suggested that O-GlcNAcylation is involved in sarcomeric structure and its interactome. This work provide new insights in the understanding of the physiopathology of some muscular diseases where the sarcomere is disorganized.
253

DEVELOPMENT OR UNDERDEVELOPMENT IN IRAN 1940-1978: A COMPARISON OF MODERNIZATION AND WORLD SYSTEM/DEPENDENCY PERSPECTIVES

Unknown Date (has links)
A central issue in the sociology of economic development of nations concerns why and how some countries have developed and others have not. The study of this question becomes important because despite sociology's preoccupation, since classical times, with the transition of societies toward more advanced social stages many questions regarding the nature of national development have been left unanswered, particularly with respect to the nonindustrialized nations. / A major assumption underlying the explanations given by traditional theories (modernization) of development is that each society is basically independent of all others, and that underdevelopment or development of any one society is caused by internal forces. / This study develops another approach based on a world-system/dependency perspective. According to this perspective the poverty of underdeveloped societies are due to their relationship with the advanced capitalist societies rather than being caused by internal conditions. / The question of development and underdevelopment is examined by applying the two theoretical frameworks to Iranian historical experiences from 1940-1978. Modernization hypotheses are found to be logically and empirically problematic or incomplete on political participation, investment capital, and liberal reforms. Alternatively, the world-system/dependency perspective tends to best conform to the Iranian Post-World War II historical experience. / Source: Dissertation Abstracts International, Volume: 43-03, Section: A, page: 0945. / Thesis (Ph.D.)--The Florida State University, 1982.
254

THE DEVELOPMENT OF UNDERDEVELOPMENT IN GRENADA (POLITICAL ECONOMY)

Unknown Date (has links)
Previous studies of development and underdevelopment of the Caribbean have viewed the region's backward state as a consequence of "antiquated institutional structures" or an "insufficiency of resources and skills necessary for economic development." / In contract to these analyses, this study attempts to obtain a better understanding of the production-reproduction of "underdevelopment"--the "development of underdevelopment"--through a detailed investigation of the historical conditions, and the totality of productions relations within one small Caribbean society the microstate of Grenada. The theoretical foundation of the study consists of the works of Marx, as elaborated upon by Andre Gunder Frank and Samir Amin. Frank and Amin are emphasized because their work represents the most comprehensive treatment of peripheral development and underdevelopment. A major assumption underlying their work is that development and underdevelopment is part of the same dynamic process as world capitalist accumulation, where the metropolis developed by exploiting the periphery which in turn became underdeveloped. A shortcoming of Frank and Amin's analysis is their economic deterministic approach to underdevelopment. By their emphasis on the economic they have failed to come to terms with the political, social-cultural, and ideological forces that contribute to underdevelopment. / Consistent with Frank and Amin this study shows that Grenada became underdeveloped as Britain extracted and expatriated the island's resources for the benefit of the metropolis. In contrast to Frank and Amin, however, the results also show that societal forces are complexly and dynamically intertwined, in short overdetermined, and that primacy cannot be attributed to economic factors as major determinants of underdevelopment. The complementarity of these forces are therefore crucial and must be adequately assessed if we are to have a better understanding of underdevelopment--not under-emphasized as Frank and Amin have done. / The findings of this work suggest that a more complete account of development/underdevelopment process emerges by taking the totality of social relations into consideration. Using this approach allows us to uncover some of the dynamic connecting links and basic characteristics of peripheral societal formations, and transformations within them--findings that will provide a more comprehensive understanding of problems of underdevelopment and possibilities for change. / Source: Dissertation Abstracts International, Volume: 46-10, Section: A, page: 3169. / Thesis (Ph.D.)--The Florida State University, 1985.
255

THE CITY AS A SOCIAL SYSTEM: THE EFFECT OF SIZE, PRODUCTIVE OUTPUT, COMPLEXITY, LEVEL OF ENERGY AND GROWTH ON SYSTEM MAINTENANCE AND REGULATION

Unknown Date (has links)
The present research was an analysis of cities as social systems, using data for the 148 SMSA's of 200,000 or larger population in 1970. It examines the relationship among variables representative of several theoretical concepts, which are system size, productive output, complexity, growth, level of energy and system investment in regulatory and maintenance functions. Variables representing the first five concepts were considered independent variables: city size, functional specialization, occupational and racial diversity, population growth and median income. Variables representing the last two concepts were considered dependent variables: city expenditures on such regulatory functions as fire and police protection, and such maintenance functions as education, welfare and health. / The hypothesis tested was that the independent variables would demonstrate a hierarchic pattern in their unique ability to explain variation in cities' expenditures for both regulatory and maintenance activities. From most powerful to least powerful the order of the independent variables was predicted to be: city size; functional specialization; level of energy characteristic of the system, as measured by median income; system complexity, as measured by racial and occupational diversity; and population growth or decline. To determine the relative contributions of each independent variable in explaining variation in the dependent variables, the analysis relied on a multiple regression procedure which isolates the unique explanatory power of each variable. The patterns observed among the independent variables were summarized and compared by describing them with appropriate path models. / Four findings were of particular interest: first, city size, traditionally regarded as a highly important variable, demonstrated little unique ability to explain variation in maintenance expenditures; second, of all types of functional specialization only the degree of specialization in metropolitan functions (financial, diversified trade and service functions) showed significant ability to explain variation in either regulatory or maintenance expenditures; third, while city size and degree of specialization in metropolitan functions were most important in determining regulatory expenditures, system complexity in terms of occupational and racial diversity was most important in determining maintenance expenditures; fourth, population growth or decline was unimportant in unique contribution to any measures of regulatory or maintenance expenditures. / Source: Dissertation Abstracts International, Volume: 43-06, Section: A, page: 2126. / Thesis (Ph.D.)--The Florida State University, 1982.
256

AN APPLICATION OF A RULES-BASED THEORY OF INTERPERSONAL COMMUNICATION: THE RULES OF TABOO COMMUNICATION WITHIN A "GAY COMMUNITY"

Unknown Date (has links)
This study investigated the interpersonal communication rules within a gay community concerning the topic being a homosexual. Though the study attempted to extract rules, its primary emphasis was to describe the factors that affect rule development. To that end, the study did the following: (1) It attempted to discover rules individuals have about what can be said, under what circumstances, and to whom; (2) It examined different labels denoting homosexuality and determined when they may be used and how individuals respond to them; (3) It investigated the information sources and communication networks of the members of a gay community; and (4) It examined the sex differences in communication practices in a gay community. / A structured and open-ended questionnaire was administered by ten interviewers to 108 respondents (fifty-five males and fifty-three females) in the Pittsburgh area. The sample was generated through the snowball technique which uses relational networks. Open-ended questions were content analyzed by four coders using techniques developed for this study. Measures were taken to support intercoder reliability, over time reliability of respondent's answers, and the validity of the content analysis techniques. Both qualitative and quantitative data were used to check the results of the directional hypotheses and research questions. / The results of the study demonstrated the difficulty of predicting the content of interpersonal rules. Whether or not the receiver was gay was not crucial for the rules of self-disclosure. Neither was mutual self-disclosure a prerequisite for self-disclosure of homosexuality. The use of code words was not important in the recognition of another gay person. The most important factor for determining the receivers of self-disclosure was whether the receiver was empathetic to various lifestyles including homosexuality. Respondents had little difficulty stating their rules of taboo communication. / There was weak support for the relationship between extent of relational networks and the restrictiveness of rules of taboo communication. This relationship was stronger for females than for males. There was strong support for the relationship between "coming out" as a homosexual and information provided by the mass media. Twenty-two percent of the sample had come out having received information only from the mass media. There appeared to be a stronger relationship for males between information provided by the mass media and the structure of taboo communication rules. / Females tended more toward interlocking networks than males. Males spent more time and got more information from diverse groups than did females. Females were more comfortable with gay males than straight males, while gay males saw little difference between gay and straight females. / Gay people responded more negatively to labels when used by straight people than to gay people using the same labels. Gay males and gay females perceived some terms differently. This was especially true for words that apply to females, as "dyke" and "lesbian." Most respondents preferred the word "gay" to "homosexual" and considered it a more positive term. Both males and females relied on prevalent stereotypes for recognition of another gay person. / Before coming out, males were dependent upon mass media sources for information, while females were more dependent upon interpersonal sources. After coming out, both groups tended to rely upon same sex gay friends for information. The major stated factor in coming out for males was assertion of self. The major stated factor in coming out for females was the influence of others. / Source: Dissertation Abstracts International, Volume: 41-03, Section: A, page: 1239. / Thesis (Ph.D.)--The Florida State University, 1980.
257

LATENT AND CONSISTENT COMMITMENT: A STUDY OF COMMITMENT AS BOTH A COGNITIVE AND BEHAVIORAL VARIABLE

Unknown Date (has links)
This study was concerned with the effect of social acts upon commitment to social responsibility. Commitment was defined as the pledging or binding of an individual to an act. It was typologized into: (a) commitment to an act which had not been previously performed, termed latent commitment; and (b) commitment to an act which had been previously performed, termed consistent commitment. / This study, basically, examined the effect of two factors upon the two types of commitment. First, the factor explicitness, whether an act is performed publically or privately, was of interest with regard to the influence that it might have upon two types of commitment. Second, the factor of number of acts performed was of interest; whether two, four, or eight acts might result in differences in the two types of commitment. / A modified social responsibility scale was administered to 216 students from East Carolina University both prior to and following the performance of acts which were manipulated in respect to explicitness and number of acts performed. Subjects were randomly assigned to the two levels of explicitness and three levels of numbers of acts. The subjects were randomized to a 2 x 3 factorial research design. / Data on the 216 subjects were analyzed using an analysis of variance (ANOVA) of a social responsibility scale. The independent variables were explicitness and number of acts performed. The conditional variables were latent commitment and consistent commitment. The scores of the subjects above midpoint on the social responsibility scale were taken as the dependent variable. / The results of the analysis of variance indicated that there were no significant differences in the latent commitment condition. The main effects of the interactions were not significantly different as a result of explicitness and/or number of acts performed. / The results of the analysis of variance indicated that there were no significant differences in the consistent commitment condition. Explicitness and number of acts performed made no significant differences in either main effects or interactions. / Source: Dissertation Abstracts International, Volume: 42-06, Section: A, page: 2891. / Thesis (Ph.D.)--The Florida State University, 1981.
258

The state and product cycle in the world system: The industrial change in South Korea

Unknown Date (has links)
East Asia's capitalist growth has generated many interesting questions concerning Third World development. While radical and critical theories tend to ignore East Asia, modernization and neoclassical economic theories offer ahistorical accounts of what has actually happened. Focusing on South Korea's rapid rise in the world-system, this study seeks to address many issues surrounding East Asian development. Three successful export industries have been chosen for a detailed examination of the dialectical interaction between the state and the world-system forces. South Korea's economic success was generally attributed to its well-orchestrated policy of following the product cycle in the international division of labor. The Korean state has effectively mastered the flow of the product cycle in the three industries, but failed to do so in the machinery and chemical sectors. Its strategy of following the product cycle was mediated by the Northeast Asian political economic system, in which Japan played a central role. Since Korea's success is historically as well as regionally specific, its model of development may not be readily adaptable for the other developing countries trying to emulate the country. / Source: Dissertation Abstracts International, Volume: 49-12, Section: A, page: 3892. / Major Professor: Richard Rubinson. / Thesis (Ph.D.)--The Florida State University, 1988.
259

Modelo molecular para sólidos covalentes / Molecular model for covalent solids

Fazzio, Adalberto 20 June 1978 (has links)
Neste trabalho propomos um modelo molecular geral para o estudo da estrutura eletrônica de sólidos covalentes, utilizando o método do Espalhamento Múltiplo. Aplicamos o modelo ao cristal de GaAs com aglomeradosde 17 átomos. Analisamos os efeitos produzidos pelos elétrons pertencentes aos orbitais flutuantes, evidenciando a necessidade de tratarmos corretamente às condições de contôrno do aglomerado. Apresentamos os resultados para o gap de energia, largura da faixa de valência e a curva densidade de estados, resultados estes que concordam satisfatoriamente com a experiência. Utilizando o modelo proposto, estudamos ainda defeitos pontuais no cristal de GaAs tais como vacância de gálio, vacância de arsênio e impurezas substitucionais de cobre e selênio. A simulação de uma vacância de gálio no GaAs provocou o aparecimento de um nível de energia aceitador (profundo) e a vacância de arsênio provocou o aparecimento de 2 níveis doadores (profundos). Com a introdução de uma impureza de cobre no GaAs surgiu um nível aceitador energeticamente próximo ao nível produzido pela vacância de gálio. A impureza de selênio no GaAs provocou o aparecimento de um nível doador (raso) próximo a faixa de condução. Todos os resultados acima apresentados concordam perfeitamente com a evidência experimental. Por último incluímos o operador de massa de Ferreira-Leite para o estudo de níveis rasos de impureza. A partir dos resultados obtidos neste trabalho e da generalidade do modelo proposto abre-se um vasto campo para o estudo defeito em sólidos covalentes. / A molecular cluster model of tetrahedrally coordinated covalent semiconductors is proposed. The boundary condition at the cluster surface is the crucial problem. A general solution to this problem is suggested. The energy spectra of GaAs cluster with seventeen atoms are obtained within the framework of the selfconsistent field multiple scattering method. A critical analysis of the \"dangling bonds\" effects on the electronic structure of the cluster is performed, and a suitable simulation of the rest of the crystal at the cluster boundaries is discussed. lt is show that the main features of the perfect crystal electronic structure emerge from the cluster spectrum, when the proposed boundary condition is assumed. The model was applied to \"the study of the electronic structure of vacancies and substitutional impurities in GaAs. The proposed cluster model leads to the correct location of the electronic levels, introduced by the .impurity, with respect to the band edges. The agreement between the calculated results and the experimental ones suggests that the molecular cluster approach proposed is reliable to deal with a wide range of problems associated with the electronic structure of perfect and imperfect IV and III-V covalent semiconductors.
260

Polarização de spin em sistemas atômicos dentro de um formalismo relativístico / Spin polarization in atomic systems within a relativistic formalism

Antonelli, Alex 08 December 1981 (has links)
O trabalho apresenta um modelo para a descrição autoconsistente da polarização de spin em sistemas atômicos, onde o elétron e tratado como uma partícula de Dirac. O Hamiltoniano de interação de muitas partículas utilizado é obtido via teoria de perturbação covariante até primeira ordem em , constante de estrutura fina, e até termos da ordem (v/c)2, onde v representa a velocidade das partículas. Tal Hamiltoniano é uma boa descrição para sistemas de elétrons interagentes até uma densidade de aproximadamente 10.26 elétrons/cm3. No trabalho procura-se descrever os estados de uma partícula como \"orbitais atômicos\" e para tanto aproximações adicionais fazem-se necessárias. Além disso, a aproximação local por um gás de elétrons livres no tratamento dos termos de \"exchange\" e utilizada. Como aplicação do modelo é feito o cálculo da estrutura de multipletos para alguns sistemas atômicos. Obtém-se, também, um pequeno desdobramento em átomos com camadas fechadas (gases nobres) devido às interações magnética e de retardamento. / A relativistic, spin polarized, self-consistent, atomic system model is presented, the electrons being described as Dirac particles. The many-body interaction Hamiltonian used is correct until the orders and (v/c)2, with standing for the fine structure constant, v and c for the velocities of particles and light respectively. Such Hamiltonian may be used for the description of interacting electrons for densities lower than 10 26 electrons/cm3. The requirement for particles states as \"atomic orbitals\" implies some additional approximation. For exchange terms the local free electron gas approximation is used. As an application the multiplet structure for some atomic systems is presented. The model describes a break of degeneracy for closed shell atoms due to the magnetic and retarded interactions.

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