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Aplicações de técnicas de RMN à determinação estrutural de intermediários sintéticos. / Applications of NMR techniques in structural determination of synthetic intermediate.Lacerda Júnior, Valdemar 30 March 2000 (has links)
A conhecida regra do acoplamento em W, que estabelece que núcleos na conformação em W planar exibem valores significativos de constantes de acoplamento através de quatro ligações, tem sido uma ferramenta útil para a determinação estrutural desde o início do uso da RMN para essa finalidade. Muitas configurações e conformações foram decididas com base nessa regra. A contínua evolução do equipamento de RMN, porém, resulta em modificações na qualidade e no número dos dados experimentais obtidos, obrigando os químicos a freqüentes revisões de seus pontos de vista sobre a importância relativa dos dados que podem ser obtidos dos espectros de RMN. O equipamento mais recente tem uma resolução maior e várias características adicionais que obscurecem um pouco os conceitos mais antigos: por um lado, o alto valor informativo de algumas técnicas modernas tais como NOE DIFF e outros métodos multi-dimensionais reduzem a importância das constantes de acoplamento; por outro lado, agora é possível determinar um número muito maior de constantes de acoplamento, devido principalmente à maior resolução. Uma conseqüência natural é que o químico agora pode explorar o uso de desdobramentos sutis em análise conformacional. Como parte de nosso trabalho de pesquisa na síntese de produtos naturais, preparamos há algum tempo um número apreciável de derivados de ciclopentanos. Nossa atenção foi fortemente atraída para certas constantes de acoplamento a longa distância (4JHH) que ocorriam em alguns destes compostos, já que uma conformação W planar não parece ser possível em ciclopentanos. Decidimos então iniciar um estudo mais detalhado dos espectros de RMN desses compostos, com vistas a uma interpretação mais clara dos dados. Inicialmente fizemos as atribuições para todos os hidrogênios, incluindo a estéreo-química de cada um, e medimos todos os valores de J para os compostos; para tanto fizemos extenso uso dos espectros de RMN tanto de 1H (300 MHz)como de 13C (75 MHz), medidas de efeito NOE, etc. Os ângulos entre as ligações e os ângulos diedros (de torção) foram calculados com programas de modelagem molecular; vários programas e métodos diferentes foram usados, para aumentar a confiabilidade. O primeiro resultado obtido é a confirmação de que 4JHH 'diferente' 0 pode ocorrer mesmo em casos em que uma conformação W planar não é possível. Mais importante, porém, é a conclusão de que há uma relação entre os valores de 4JHH e os ângulos diedros envolvidos. O acoplamento entre H1 e H2 ocorre através das quatro ligações 'sigma' definidas pelo caminho H1-C1-C2-C3-H2 e envolve dois ângulos diedros 'teta'1 e 'teta'2. Os valores de 4JHH foram plotados contra (cos2'teta'1 x cos2'teta'2) (uma simples extensão da equação de Karplus); os pontos resultantes não se alinham com perfeição sobre uma curva contínua, mas mostram clara tendência de aumento do valor de 4JHH conforme os ângulos 'teta'1 e 'teta'2 se afastam de 90º e se aproximam de 180º. / The well known W rule, which establishes that nuclei in a planar W arrangement exhibit significant four bond coupling constants, has been a useful tool in molecular structure determination since early times of the use of nmr spectra for this purpose. Many configurations and conformations have been decided based on this rule. The continuous evolution of the nmr equipment, however, produces modifications in quality and number of available experimental data, thus forcing the chemists to frequent revisions of their points of view about the relative importance of the data that can be obtained from nmr spectra. The more recent equipment has a higher resolution and several additional features that throw some shadow over early concepts: on one hand, the high power of modern techniques such as NOE DIFF and other multi-dimensional methods reduce the importance of coupling constants; on the other hand, it is now possible to determine many more coupling constants, due mainly to the higher resolution. A natural consequence is that the chemist can now exploit the use of subtle splittings in conformational analysis. As part of our research work on the synthesis of natural products, we have prepared a number of cyclopentane derivatives. Our attention was strongly attracted to the long-range (4JHH) coupling constants that occurred in some of these compounds, as no planar W conformation seems to be possible in cyclopentanes. We have thus decided to start a more detailed study of the nmr spectra of these compounds, seeking for more clear interpretation of the data. We have first assigned all hydrogens, including the stereochemistry of each hydrogen, and measured all J values for the compounds; for this task we have used nmr spectra both of 1H (300 MHz) and 13C (75 MHz), NOE measurements, etc. Bond angles and dihedral (torsion) angles were calculated with molecular modeling programs; several different programs and methods were used to improve reliability. The first result obtained is a confirmation that a 4JHH 'different' 0 occurs even in cases where a planar W conformation is not possible. More important, however, is the conclusion that there is a correlation between the 4JHH values and the involved dihedral angles. There are two dihedral angles in the path through the bonds between two hydrogens which show 4JHH coupling. When 4JHH values are plotted against(cos2'teta'1 x cos2'teta'2) (a simple extension of Karplus equation) the points are not aligned over a continuous curve, but they show a clear tendency: 4JHH values become higher as the angles 'teta'1 and 'teta'2 vary from 90 to 180º.
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Alliages Ni-W : de la mise en oeuvre par frittage flash aux micro-mécanismes de déformation et d'endommagement / Ni-W alloys : from the Processing by Spark Plasma Sintering to the Deformation Micro-mechanisms and DamageSadat, Tarik 18 December 2015 (has links)
Dans le cadre de ce projet de thèse, des microstructures innovantes « composites » Ni-W constituées d’amas de Tungstène multi-cristallins (à grains fins) immergés dans une matrice de la solution solide Ni(W) cfc ont été élaborées par frittage flash (Spark Plasma Sintering (SPS)). Différents alliages ont ainsi été fabriqués en contrôlant de manière très précise les fractions volumiques respectives des deux élément Ni et W. En outre, le fait que le Ni soit un matériau particulièrement ductile contrairement au W plus résistant, peut conférer au matériau un bon compromis ductilité/résistance mécanique. Ainsi, en ajustant les taux respectifs de Ni et/ou de W, nous avons réussi à faire cohabiter dans un même matériau les micro-mécanismes de déformation propres à chaque phase, dont les caractéristiques et les évolutions sont ensuite analysées lors de sollicitations mécaniques conventionnelles ou in situ sous Synchrotron. Ainsi, nous avons mis en évidence le rôle de chacune des phases constituant la microstructure vis-à-vis du comportement macroscopique. Il est clairement montré que la proportion et l’arrangement spatial de la phase de W sont des facteurs influents sur la fragilité d’ensemble ainsi que sur les transferts de charge entre phases. Concernant la phase ductile, nous avons pu mesurer des déformations du réseau cristallin d’amplitude inhabituelle, que nous avons reliées à la densité initiale importante de joints de type ∑3, densité qui ensuite diminue fortement sous sollicitation mécanique. / As part of this thesis project, innovative “composites” microstructures Ni-W composed by clusters of multi crystallized (ultra fine grain) W embedded in a matrix of a cfc Ni(W) solid solution were elaborated by spark plasma sintering (SPS). Several alloys were processed by controlling precisely the respective volume fractions of the two elements Ni and W. In addition, Ni is a particularly ductile material unlike the more resistant W. So, it may give to the material a good compromise between ductility and mechanical resistance. Thus, by adjusting the respective fractions of Ni and/or W, we obtained in the same material the specific deformation micro-mechanisms of each phase, the characteristics and evolutions of those deformations were after analyzed during conventional mechanical stresses or under in situ Synchrotron. Thus, we have highlighted the role of each phase constituting the microstructure regarding the macroscopic behavior. It is clearly shown that the proportion and spatial distribution of the W phase are key factors on the overall brittleness as well as on the load transfer between the phases. Concerning the ductile phase, we underscored deformations of unusual amplitude, which are connected to the high initial density of ∑3 boundary grains, which then decreases sharply under mechanical stress.
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Experiência estética e Educação: a contribuição filosófica de Theodor Wiesengrund-AdornoKiihl, Raniely do Nascimento 28 March 2013 (has links)
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Previous issue date: 2013-03-28 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / A intenção principal desta pesquisa foi extrair elementos e inspiração do conceito de experiência estética presente na filosofia adorniana com o intuito de contribuir para o fortalecimento da teorização educacional crítica. Procuramos com isso pensar a escola enquanto lugar de experiência. Optamos por realizar uma pesquisa teórica na tentativa de ir a contrapelo aos aspectos pragmáticos do conhecimento. Dessa forma, não pretendemos dar respostas prontas à práxis educacional, mas sim refletir sobre o que compõe o trabalho educativo. Utilizamos como principal referencial teórico o filósofo Theodor W. Adorno, um dos teóricos mais eminentes da Escola de Frankfurt. Adorno considera que os produtos da indústria cultural operam no processo de regressão dos sentidos humanos e tem a semiformação como aliada e consequência direta da sua ação. A reflexão sobre a experiência com a arte se faz necessária diante deste contexto em que a arte se transforma em mercadoria e perde autenticidade e autonomia, ao mesmo tempo em que a sensibilidade é danificada frente à relação de troca estimulada pela sociedade do consumo. Ao final do estudo, foi possível concluir que, para Adorno, a experiência estética não é apenas emoção, mas também um processo de reflexão, de conhecimento e de formação. Dessa forma, o conceito pode servir de inspiração para se pensar o trabalho educativo no âmbito das teorias educacionais críticas, pois possui a responsabilidade de enriquecer o repertório cultural dos alunos e permite que tenham condições objetivas para se apropriarem do legado material e não material historicamente produzido / The main intention of this research was to extract elements and inspiration from the concept of aesthetic experience this philosophy Adorno in order to contribute to the strengthening of critical educational theory. We try to think that the school as a place of experience. We chose to perform a theoretical research in an attempt to go against the grain to the pragmatic aspects of knowledge. Thus, we do not intend to give prompt answers to educational praxis, but think about what makes up educational work. We used as the main theoretical philosopher Theodor W. Adorno, one of the most prominent theorists of the Frankfurt School. Adorno believes that the cultural industry products operate in the process of regression of human senses and has a semi-formation as an ally and a direct consequence of his action. Reflecting on the experience with art is necessary within this context in which art becomes a commodity and loses authenticity and autonomy, while the sensitivity is impaired compared to the exchange ratio stimulated by consumer society. At the end of the study, it was concluded that, for Adorno, the aesthetic experience is not only emotion, but also a process of reflection, knowledge and training. Thus, the concept can serve as inspiration to think the educational work within the educational theories criticism because it has a responsibility to enrich the cultural repertoire of the students and allows them to have objective conditions to appropriate the legacy material and nonmaterial historically produced
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Mesure du rapport des sections efficaces des bosons W et Z produits en association avec un jet dans les collisions proton-proton a √ s=7 TeV avec le detcteur ATLAS / Measurement of the ratio of the W and Z cross sections with exactly one associated jet in pp collisions at √ s=7 TeV with ATLASXu, Chao 05 June 2012 (has links)
Dans cette thèse la mesure du rapport des sections efficaces de production de bosons W et Z en association avec un jet au LHC est effectuée.Le rapport des sections efficaces est mesuré à l'aide des données issues de collisions proton-proton au LHC à une énergie dans le centre de masse de 7 TeV, recueillies par l'expérience ATLAS en 2010, correspondant à une luminosité intégrée d'environ 40 pb-1. L'analyse est effectuée à l’aide de bosons W et Z se désintégrant dans le canal muon.Il s'agit de la première mesure du rapport des taux de production de bosons W et Z associés à un jet réalisée à une si haute énergie dans le centre de masse, la mesure est la également la première effectuée au LHC. Cette mesure constitue un test très important des calculs théoriques perturbatifs et tire avantage des annulations partielles ou totales de diverses incertitudes expérimentales.La mesure sert aussi pour les recherches de nouveaux phénomènes de physique au LHC à contraindre les bruits de fonds ayant les mêmes signatures topologiques.La valeur du rapport de mesuré est présentée en fonction de différents seuils d’impulsion transverse de jet cumulatifs et est trouvé, a l’intérieur de la précision statistique, en bon accord avec prédictions pertubatives de QCD aux LO et NLO. / In this thesis an investigation of the ratio of the production cross section of W and Z bosons in association with one jet at LHC is performed.The cross-section ratio is measured with LHC proton-proton collision data at a center-of-mass energy of 7 TeV, collected by the ATLAS experiment in 2010, corresponding to an integrated luminosity of approximately 40 pb-1. The analysis is performed selecting W and Z bosons decaying in the muon channel.It is the first time the ratio of W and Z bosons production associated with one jet is measured at such a high center-of-mass energy, the measurement is the first one at the LHC. This measurement constitutes a very important test of perturbative theoretical calculations based on the advantage of the partial and full cancellations of various uncertainties.It also serves as constraining backgrounds with similar topological signatures in the search for new physics phenomena at the LHC. The measured ratio value is presented as a function of cumulative jet transverse momentum thresholds and found, within statistical precision, to agree well with perturbative LO and NLO QCD predictions.
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Contributions à une première mesure de la masse du boson W dans le canal électronique auprès du détecteur ATLAS / Contributions to a first measurement of the W-boson mass in the electron channel with the ATLAS detectorHanna, Rémie 29 September 2015 (has links)
Dans ce document, je présente mes contributions à une première mesure de la masse du boson W au LHC, exploitant 4.7 fb⁻¹ de données à 7 TeV, collectées en 2011. Je me concentre surtout sur le canal électronique, W → eν. Dans la première partie, j’aborde des études de performance du calorimètre électromagnétique d’ATLAS, proposant une méthode innovante de correction des profils latéraux de dépôt d'énergie des électrons. Des études de différentes versions de Geant4 sont également abordées. Dans la deuxième partie, je détaille mes contributions après avoir introduit la méthode globale de mesure de la masse du boson W adoptée par ATLAS : je présente dans un premier temps le calcul d’incertitudes systématiques introduites par la modélisation des gerbes de partons dans Pythia8, et une optimisation de l’intervalle d’ajustement en utilisant l’impulsion transverse du lepton, dans le but de réduire les incertitudes correspondantes. Dans un deuxième temps, je présente une estimation de bruit de fond provenant de jets de partons, dans le canal W → eν, en développant une méthode basée sur les données, ainsi que les résultats correspondants, en termes de nombre d’événements et de fractions par rapport aux données. Les incertitudes sur la masse du W provenant de cette méthode sont aussi détaillées. Enfin, un état de l’art de l’analyse est montré, en détaillant les incertitudes dans le canal électronique, en fonction de la pseudo-rapidité et du bruit d’empilement. / In this document, I present my contributions to a first measurement of the W-mass in the LHC using 4.7 fb⁻¹ of 7 TeV data, taken in 2011. I focus on the electron decay channel, W → eν. In the first part, I discuss a study regarding the performance of the electromagnetic calorimeter of the ATLAS detector, presenting a novel method to correct the lateral profiles of electron energy deposit, along with various studies of the different Geant4 physics lists versions. In the second part, I introduce the global methodology for the W-mass measurement used in ATLAS, and discuss my contributions in details. I show in a first step the assessment of uncertainties coming from the parton shower modeling in Pythia8, and the optimization of the lepton's transverse momentum fitting range in order to reduce the systematic uncertainty. In a second step, I present an elaborate data-driven method for the estimation of the multijet background in the W → eν channel, as well as the corresponding results in terms of event yields and fractions with respect to the signal data. The corresponding uncertainties on the W-mass are also shown. Finally, I show the state of the art of the analysis, by gathering the full breakdown of the uncertainties, in bins of pseudorapidity and average pileup.
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Multilateralism à la Carte? : The Bush II administration and US foreign policyZyla, Benjamin January 2007 (has links)
The use of unilateral force under George W. Bush is not a new phenomenon in US foreign policy. As the author argues, it is merely a continuation of Bill Clinton’s foreign policy and is deeply rooted in both the foreign policy traditions of Jacksonianism and Wilsonianism. The analysis concludes that Clinton used unilateralist foreign policy with a 'smile' whereas the Bush administration uses it with an attitude. / Die unilaterale Außenpolitik unter George W. Bush ist kein neues Phänomen der US-Diplomatie. Dem Autor zufolge ist sie vielmehr eine Fortführung der Politik der Clinton-Regierung und hat ihre Wurzeln in den Traditionen eines Andrew Jackson und Woodrow Wilson. Clinton vermochte jedoch seine unilaterale Politik mit einem "Lächeln" zu verkaufen, wohingegen die Art und Weise der Bush-Administration stets Irritationen hervorrief.
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Unterstützung der ukrainischen Genehmigungs- und Aufsichtsbehörde bei der Einrichtung einer verbesserten betrieblichen Überwachung für das KKW Rovno (5. Realisierungsstufe)Carl, Helmar, Beyer, Matthias, Kriks, Jakob 31 March 2010 (has links) (PDF)
In Analogie zum Pilotprojekt für den 5. Block vom KKW Saporoshje - WWER-1000/W-320 - wurde für die beiden WWER-440/W-213 Blöcke vom KKW Rovno eine verbesserte betriebliche Überwachung eingerichtet. Dazu werden dem Vor-Ort-Inspektor am KKW Standort und der Aufsichtsbehörde in Kiew einmal pro Minute 55 aktuelle sicherheitsrelevante Parameter pro Block und 7 standortspezifische Parameter zur Erfassung und Bewertung mittels moderner technischer Mittel on-line zur Verfügung gestellt. Die zur Ausstattung des Arbeitsplatzes des Vor-Ort-Inspektors unbedingt benötigten Ausrüstungen wurden unter Berücksichtigung der aktuellen Anforderungen des KKW Rovno spezifiziert, beschafft und der ukrainischen Seite unentgeltlich überlassen. Bei Funktionstests Ende 1998/Anfang 1999 wurden Datensätze aus dem lokalen Rechnernetz des KKW Rovno fehlerfrei nach Kiew übertragen und auf einem Rechner im Informations- und Krisenzentrum in Form von Tabellen, Grafiken und Schemata dargestellt.
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W. H. Hudson between art and science /Imhoff, Joshua L.. January 2009 (has links)
Title from first page of PDF document. Includes bibliographical references (p. 43-45).
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Geology, surface hydrology, and fish habitat relationships in the upper Shavers Fork drainage basin, West VirginiaGaujot, Ryan Cooley. January 2002 (has links)
Thesis (M.S.)--West Virginia University, 2002. / Title from document title page. Document formatted into pages; contains x, 85 p. : ill. (some col.), maps (some col.). Includes abstract. Includes bibliographical references (p. 62-69).
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Native literature in Canada a comparative study of the coyote trickster in the literature of Thomas King and W.P. Kinsella /Fergusson, Stephen, January 1900 (has links) (PDF)
Thesis (M.A.)--Université de Sherbrooke, 1999. / Includes bibliographical references.
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