Dissertations / Theses on the topic 'Diagram correlation'

Neuroscientists are increasingly overwhelmed by new recordings of the nervous system. These recordings are significantly increasing in size due to new electrophysiological techniques, such as multi-electrode arrays. These techniques can simultaneously record the electrical activity (or spike trains) from thousands of neurons. These new datasets are larger than the traditional datasets recorded from single electrodes where fewer than ten spike trains are usually recorded. Consequently, new tools are now required to effectively analyse these new datasets. This thesis describes how techniques from the field of Visual Analytics can be applied to detect specific patterns in spike train data. These techniques are realised in a software tool called Neurigma. Neurigma is a collection of visual representations of spike train data that are unified to provide a coordinated representation of the data. The visual representations within Neurigma include: an interactive raster plot, an improved correlation grid, a novel representation called the correlation plot (which includes a novel coupling estimation algorithm), and a novel network diagram. These views provide insight into spike train data, and particularly, they identify correlated patterns, called functional connectivity. Within this thesis Neurigma is used to analyse synthetically generated datasets and experimental recordings. Three main findings are presented. First, propagating spiral patterns are identified within recordings from the neonatal mouse retina. Second, functional connectivity is identified within the cat visual cortex. Finally, the functional connectivity of a large synthetic dataset, of 1000 spike trains, is accurately classified into direct, indirect and common input coupling.

There has been very little research into the bioanalytical application of Microemulsion High Performance Liquid Chromatography (MELC), a recently established technique for separating an active pharmaceutical ingredient from its related substances and for determining the quantity of active drug in a dose. Also, the technique is not good at separating hydrophilic drugs of very similar chemical structures. Different phase diagrams of oil (octane or ethyl acetate), co-surfactant (butanol), surfactant (sodium dodecyl sulphate (SDS) or Brij-35) and buffer (Phosphate pH 3) were developed and several nanoemulsion mobile phases identified. Nanoemulsion mobile phase that is, prepared with SDS, octane, butanol and a phosphate buffer, failed to separate hydrophilic compounds with a very close chemical structure, such as terbutaline and salbutamol. A nanoemulsion mobile phase containing a non-ionic surfactant (Brij-35) with ethyl acetate, butanol and a phosphate buffer, was, however, successful in achieving a base line separation, and the method was validated for simultaneous determination of terbutaline and salbutamol in aqueous and urine samples. An oil-in-water (O/W) NELC method was developed and validated for the determination of formoterol in an Oxis® Turbuhaler® using pre-column fluorescence derivatisation. Although the same mobile phase was extended for separation of formoterol in urine, the formoterol peak¿s overlap with endogenous peaks meant that fluorescence detection could not determine formoterol in urine samples. Solid phase extraction, concentrating the final analyte 40 times, enabled determination of a low concentration of formoterol in urine samples by UV detection. The method was validated and an acceptable assay precision %CV <4.89 inter-day and %CV <2.33 intra-day was achieved. Then after the application of O/W nanoemulsion mobile phase for HPLC was extended for the separation of lipophilic drugs. The nanoemulsion liquid chromatography (NELC) method was optimised for the determination of salmeterol and fluticasone propionate in good validation data was achieved. This thesis shows that, in general, the performance of O/W NELC is superior to that of conventional High Performance Liquid Chromatography (HPLC) for the analysis of both hydrophilic and lipophilic drugs in inhaled dosage formulations and urine samples. It has been shown that NELC uses cheaper solvents and that analysis time is faster for aqueous and urine samples. This considerable saving in both cost and time will potentially improve efficiency within quality control.

There has been very little research into the bioanalytical application of Microemulsion High Performance Liquid Chromatography (MELC), a recently established technique for separating an active pharmaceutical ingredient from its related substances and for determining the quantity of active drug in a dose. Also, the technique is not good at separating hydrophilic drugs of very similar chemical structures. Different phase diagrams of oil (octane or ethyl acetate), co-surfactant (butanol), surfactant (sodium dodecyl sulphate (SDS) or Brij-35) and buffer (Phosphate pH 3) were developed and several nanoemulsion mobile phases identified. Nanoemulsion mobile phase that is, prepared with SDS, octane, butanol and a phosphate buffer, failed to separate hydrophilic compounds with a very close chemical structure, such as terbutaline and salbutamol. A nanoemulsion mobile phase containing a non-ionic surfactant (Brij-35) with ethyl acetate, butanol and a phosphate buffer, was, however, successful in achieving a base line separation, and the method was validated for simultaneous determination of terbutaline and salbutamol in aqueous and urine samples. An oil-in-water (O/W) NELC method was developed and validated for the determination of formoterol in an Oxis® Turbuhaler® using pre-column fluorescence derivatisation. Although the same mobile phase was extended for separation of formoterol in urine, the formoterol peak's overlap with endogenous peaks meant that fluorescence detection could not determine formoterol in urine samples. Solid phase extraction, concentrating the final analyte 40 times, enabled determination of a low concentration of formoterol in urine samples by UV detection. The method was validated and an acceptable assay precision %CV <4.89 inter-day and %CV <2.33 intra-day was achieved. Then after the application of O/W nanoemulsion mobile phase for HPLC was extended for the separation of lipophilic drugs. The nanoemulsion liquid chromatography (NELC) method was optimised for the determination of salmeterol and fluticasone propionate in good validation data was achieved. This thesis shows that, in general, the performance of O/W NELC is superior to that of conventional High Performance Liquid Chromatography (HPLC) for the analysis of both hydrophilic and lipophilic drugs in inhaled dosage formulations and urine samples. It has been shown that NELC uses cheaper solvents and that analysis time is faster for aqueous and urine samples. This considerable saving in both cost and time will potentially improve efficiency within quality control.

In thisproject, solubility of butyl paraben in 7 puresolvents and 5 ethanol aqueous solvents has been determined at from 1 ℃to 50 ℃. Thermodynamic properties of butyl paraben have been measured by DifferentialScanning Calorimetey. Relationship between molar solubility of butyl paraben in6 pure solvents and thermodynamic properties has been analyzed. Thisrelationship suggests a method of estimating activity of solute at equilibrium fromcombining solubility data with DSC measurements. Then, activity coefficient accordingto the solubility at different temperatures can be estimated. Duringthe solubility measurements in ethanol aqueous solvents, it is found that whenbutyl paraben is added into aqueous solutions with certain proportion ethanol,solutions separates into two immiscible liquid layers in equilibrium. Water andethanol are primary in top layer, while the butyl paraben is primary in bottomlayer, but the solution turns to cloudy when two layers of solution are mixed. Theaim of this work was to present the phase behaviour of liquid-liquid-phaseseparation for (butyl paraben + water + ethanol) ternary system from 1 ℃ to 50 ℃at atmospheric pressure. Thearea of liquid-liquid-phase separation region in the ternary phase diagram increaseswith the increasing temperature from 10 ℃to 50 ℃. In thisstudy, more than several hundreds of nucleation experiments of butyl paraben havebeen investigated in ethyl acetate, propanol, acetone and 90% ethanol aqueoussolution. Induction time of butyl paraben has been determined at 3 differentsupersaturation levels in these solvents, respectively. Free energy ofnucleation, solid-liquid interfacial energy, and nuclei critical radius havebeen determined according to the classical nucleation theory. Statistical analysis ofinduction time reveals that the nucleation is a stochastic process with widevariation even at the same experiment condition. Butyl paraben nucleates most difficultlyin 90 % ethanol than in other 3 solvents, and most easily in acetone. The interfacialenergy of butyl paraben in these solvents tends to increasing with decreasemole fraction solubility in these solvents. Coolingcrystallizations with different proportions of butyl paraben, water and ethanolhave been observed by Focused Beam Reflectance Method, Parallel VirtualMachine, and On-line Infrared. The FBRM, IR curves and the PVM photos show someof the solutions appeared liquid-liquid phase separation during coolingcrystallization process. The results suggest that if solutions went throughliquid-liquid phase separation region during the cooling crystallizationprocess the distribution of crystals crystal was poor. Droplets from solutions withsame proportion butyl paraben but different proportions of water and ethanolhave been observed under microscope. Induction time of the droplets has been determinedunder the room temperature. Droplets from top layer or bottom layer of solutionwith liquid-liquid phase separation on small glass or plastic plates were alsoobserved under microscope. The microscope photos show that the opposite flows ofcloudy solution on the glass and the plastic plate before nucleation. The resultsof the cooling and evaporation crystallization experiments both revealed thatnucleation would be prevented by the liquid-liquid phase separation.
QC 20110630

Nous avons fait une etude theorique de certaines proprietes du reseau kondo dans sa phase paramagnetique, utilisant un modele incorporant des correlations antiferromagnetiques a courte portee. Nous nous sommes limites au cas de la bande de conduction a moitie pleine et avons utilise une methode de champ moyen. Les resultats obtenus sont les suivants : _ on montre qu'il est possible d'obtenir des solutions metalliques pour une bande de conduction a moitie pleine en modifiant la structure de bande, ceci nous amene a definir une temperature de transition isolant-metal qui est comparee aux temperatures kondo et de coherence. _ nous recherchons ensuite des phases magnetiquement ordonnees par deux methodes : introduction d'un moment magnetique sur chaque site comme parametre de champ moyen et etude de la susceptibilite statique en rpa. Nous obtenons ainsi des phases purement kondo ou purement magnetiques, mais nous n'avons pas trouve de phase mixte kondo-magnetique. _ les fluctuations des parametres kondo et magnetique sont ensuite traitees dans le cadre de l'approximation rpa. Ceci permet de calculer leur contribution a la chaleur specifique. Un comportement de fermion lourd est mis en evidence pour certaines valeurs des constantes de couplage. Au voisinage de la transition isolant-metal, un comportement de non liquide de fermi est obtenu.

Orientador: Rogério Custodio
Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Química
Made available in DSpace on 2018-08-18T08:56:05Z (GMT). No. of bitstreams: 1 Abreu_Leandrode_M.pdf: 3333566 bytes, checksum: 9df2fe3268e83e70fae31b792fc76513 (MD5) Previous issue date: 2011
Resumo: Este trabalho avaliou o cálculo de energias de ionização verticais e as possibilidades de construção e interpretação de diagramas de correlação através do uso dos métodos Monte Carlo Quântico (MCQ) e Outer Valence Green¿s Function (OVGF). O trabalho foi dividido em quatro partes: Energias de ionização simples: Avaliou-se a capacidade dos métodos MCQ e OVGF em descrever os valores de energia de ionização de valência e de caroço e testou-se o uso de funções de onda relaxadas. A faixa dos desvios observados obtidas com o método Monte Carlo Quântico de Difusão (MCQD), em relação aos valores experimentais, é comparável a de outros métodos, como DFT (Teoria do Funcional de Densidade - Density Functional Theory) e CCGF (Funções de Green com Pares Acoplados - Coupled-Cluster Green¿s Function), 0,01 a 2 eV, e verificou-se que uso das funções de onda relaxadas é importante na descrição das ionizações de caroço. Energias de ionização sucessivas: Estimou-se as energias de ionização sucessivas dos elementos do 2º período a partir das energias orbitais do sistema neutro e comparou-se com resultados obtidos através dos métodos MCQ utilizando-se a função de onda do sistema não-ionizado. Pode-se demonstrar a falha das energias orbitais em descrever as energias de ionização sucessivas e obter correções com o uso dos métodos MCQ. Diagramas de correlação: Construíram-se diagramas de energia eletrônica total e de correlação quantitativos utilizando energia de ionização como binding energy para moléculas do tipo BAB (H2O e Li2O) através do uso dos métodos MCQ. Foram construídos diagramas de cargas parciais de Bader através das distribuições discretas de carga obtidas com os métodos MCQ para tentar interpretar os diagramas de correlação, porém a interpretação por comparação direta não foi possível, contudo foram obtidas informações importantes através dos diagramas de cargas parciais. Energias de dupla ionização: Foram calculadas energias de dupla ionização de sistemas atômicos e moleculares através do método OVGF e compararam-se os resultados obtidos com a Teoria do Funcional de Densidade (DFT). O método OVGF mostrou-se tão preciso quanto a teoria DFT na descrição das energias de dupla ionização
Abstract: The study was divided into 4 parts: Simple Ionization Energies: We evaluated the ability of MQC and OVGF methods in describing the values of the ionization energy of valence and core and tested the use of relaxed wave functions. The range of deviations obtained with the method of diffusion quantum Monte Carlo (MCQD), in relation to the experimental values, is comparable to other methods such as DFT (Density Functional Theory) and CCGF (Coupled-Cluster Green's Function), from 0.01 to 2 eV, and it was found that the use of the relaxed wave functions is important in the description of core ionizations. Successive Ionization Energies: We estimated the successive ionization energies of successive elements of the 2nd period from the orbital energies of the neutral system and compared with results obtained using the methods MCQ with the wave function of nonionized system. It can be shown the failure of the orbital energies to describe the successive ionization energies and to obtain corrections with the use of MCQ methods. Correlation Diagrams: Diagrams of total electronic energy and quantitative correlation diagrams were constructed using the ionization energy as binding energy for molecules of the type BAB (Li2O and H2O) through the use of MCQ methods. We constructed Bader¿s partial charges diagrams with the discrete charge distributions obtained with MCQ methods to try to interpret the correlation diagrams, but the interpretation by direct comparison was not possible, however, important information was obtained through diagrams of partial charges. Double Ionization Energies: We calculated double ionization energies of atomic and molecular systems by the OVGF method and compared the results obtained with the Density Functional Theory (DFT). The OVGF method proved to be as accurate as the DFT theory in describing the double ionization energies
Mestrado
Físico-Química
Mestre em Química

Cette thèse s'intéresse à deux types de systèmes de différents degrés de liberté en interaction, et soumis à des fluctuations quantiques.Dans le premier projet abordé dans le manuscrit, on établit un diagramme de phase d'électrons en interactions dans un cristal bidimensionnel à géométrie kagome. Ce diagramme de phase est dressé en fonction de deux paramètres étant les interactions coulombiennes entre électrons sur un même atome pour le premier, et sur des atomes plus proches voisins pour le second. Les énergies caractéristiques de ces deux interactions sont quantifiées par rapport à une énergie de référence étant celle des fluctuations quantiques. On met alors en évidence quatre phases dont deux sont nouvelles, alors que les deux autres font le lien avec la littérature déjà existante, et sont en accord avec cette dernière. Ces deux nouvelles phases émergent lorsque l'énergie de répulsion coulombienne entre électrons sur un même atome domine devant l’énergie caractéristique des fluctuations quantiques. En présence d’une forte répulsion coulombienne entre électrons sur des atomes plus proches voisins, les charges électroniques ne peuvent se délocaliser pour former des ondes de Bloch et sont soumis à ce que l’on appelle une contrainte locale de charge. Apparaissent alors sous la compétition de ces deux interactions coulombiennes, des modes unidimensionnels collectifs le long des chaines d’atomes antiferromagnétiquement ordonnées. Ces modes ont la particularité d’être stabilisés à la fois par les fluctuations des degrés de liberté de spin, et de charge des électrons. La seconde de ces nouvelles phases émerge lorsque la répulsion coulombienne entre électrons sur des atomes voisins devient faible devant les fluctuations quantiques. La contrainte locale est alors relâchée et les électrons forment des ondes de Bloch le long de ce qui s’apparente à des bulles quantiques unidimensionnelles et polarisées en spin. Ces bulles sont alors piégées dans un cristal d’électrons inversement polarisés, avec lesquels elles sont en interaction antiferromagnétique.Le second projet porte sur l’étude d’un aimant moléculaire de Terbium Double-Decker. Cette molécule peut être modélisée par trois degrés de liberté interagissant en cascade les uns avec les autres. Le premier d’entre eux est un degré de liberté de spin nucléaire porté par le noyau de l’ion terbium de la molécule. Ce spin nucléaire est en interaction d’échange avec un degré de liberté de spin électronique porté par les électrons de l’ion terbium. Enfin, en première approximation, ce spin électronique génère un champ dipolaire auquel sont soumis les deux ligands de l’aimant moléculaire. Ces deux ligands sont couplés à deux électrodes de source et de drain, assurant le transport d’électrons uniques à travers ces deniers. Le tout forme donc un transistor à électron unique dans lequel les ligands servent de boîte quantique. Par mesure de magnéto-conductance, il est donc possible par une lecture en cascade, de remonter à l’état du spin électronique et du spin nucléaire. La première étape du projet a donc consisté à établir un modèle décrivant l’aimant moléculaire couplé à ces deux électrodes, afin de prédire les mesures de conductance réalisées au travers du transistor lors des thèses de Stefen Thiele et Clément Godfrin. Les résultats théoriques et expérimentaux obtenus sont en accord quantitatifs.D’autres part, à l’aide de champs électriques radio-fréquences, il est possible de manipuler expérimentalement et de façon cohérente le spin nucléaire. Cette manipulation cohérente du spin nucléaire se fait par l’intermédiaire du nuage électronique de l’ion, et permet ainsi d’être en mesure de réaliser un algorithme quantique sur le spin nucléaire de l’ion terbium. La réalisation d’un programme de simulation a permis de guider la réalisation expérimentale de l’algorithme de Grover, lequel a été implémenté avec succès au cours de la thèse de Clément Godfrin
This thesis focuses on two different spin and charge systems, interacting under the effect of quantum fluctuations.The first project highlights the phase diagram of interacting electrons on a kagome lattice. This diagram is driven by two Coulomb repulsions. The first is a on site repulsion, and the second a nearest neighbor one. These two repulsions are in competition with quantum fluctuations of electronic charges. Four phases are depicted, two are unknown and the two other are in agreement with the literature. The two new phases are stabilized in the strong on site repulsion regime. When nearest neighbor repulsions are strong enough to induce a charge local constraint, the system enters in a so called Heisenberg-Loop Phase. These loops are antiferromagnetically arranged and can be described by a Heisenberg-like model in which both charge and spin play surprisingly a role in the exchange interaction. The second new phase is stabilized in the regime where nearest neighbor interactions are too weak to maintain the local constraint. Then, half of the electrons are delocalized in unidimensional Bloch states similar to quantum polarized electronic bubbles. These bubbles are trapped in an inversely polarized electronic cristal formed by the other electrons. This peculiar phase is favored by both quantum charge fluctuations in the bubbles, and antiferromagnetic exchanges between their electrons and the cristal ones.The second project deals with a Terbium Double-Decker molecular magnet. This molecule is modeled by three interacting degrees of freedom. The first is a nuclear spin of the Terbium ion, and the second is the electronic spin of this same ion. The two spins interact via a magnetic exchange.In a first approximation, the effect of the electronic spin is to induce a dipolar field. Finally, the last degree of freedom is carried by two ligands under the influence of the dipolar field. The ligands play the role of a read-out quantum dot, and by conductance measurements through this last one, we can probe the electronic spin and then, the nuclear spin. The first step of this project highlights the modeling of the global system. Then numerical computations are depicted and are in a quantitative agreement with the experimental measurements realized during the thesis of Stefan Thiele and Clément Godfrin.On the other hand, by applying electrical Radio Frequency Fields, we can drive quantum fluctuations on the nuclear spin. This quantum manipulation of the spin is realized by the dynamic deformation of the electron cloud under the effect of the Radio Frequency Field. As a result, we are able to implement a Grover Quantum Algorithm on the nuclear field. This thesis focuses on the realization of a simulation program that was a tool used by Clément Godfrin to successfully implement the Grover Algorithm

The concept of the transfer Hamiltonian formalism has been reconsidered and generalized to include the non-orthogonality between the electron states in an interacting region, e.g. quantum dot (QD), and the states in the conduction bands in the attached contacts. The electron correlations in the QD are described by means of a diagram technique for Hubbard operator Green functions for non-equilibrium states.

It is shown that the non-orthogonality between the electrons states in the contacts and the QD is reflected in the anti-commutation relations for the field operators of the subsystems. The derived forumla for the current contains corrections from the overlap of the same order as the widely used conventional tunneling coefficients.

It is also shown that kinematic interactions between the QD states and the electrons in the contacts, renormalizes the QD energies in a spin-dependent fashion. The structure of the renormalization provides an opportunity to include a spin splitting of the QD levels by polarizing the conduction bands in the contacts and/or imposing different hybridizations between the states in the contacts and the QD for the two spin channels. This leads to a substantial amplification of the spin polarization in the current, suggesting applications in magnetic sensors and spin-filters.

La découverte en 2008 de supraconductivité à relativement haute température (Tc,max = 56K) dans les pnictures de Fer a ravivé les questions fondamentales sur l'origine et la nature de la supraconductivité posés par les supraconducteurs non conventionnels. En particulier, la présence d'une phase antiferromagnétique à proximité de celle supraconductrice dans leur diagramme de phase pose la question du lien entre magnétisme et supraconductivité. Ces supraconducteurs à base de Fe présentent un diagramme de phase générique, mais quelques exceptions remettent en question une description qui se voudrait universelle. Nous avons choisi d'étudier ces cas particuliers grâce à une sonde locale, la résonance magnétique nucléaire (RMN). Nos observations nous ont non seulement permis de comprendre la raison de ces exceptions, mais aussi de s'en servir pour mieux sonder les corrélations magnétiques dans ces matériaux, un ingrédient clé pour la compréhension de la supraconductivité. Premier sujet, la coexistence de supraconductivité et de magnétisme : celle-ci a été observée dans la plupart des supraconducteurs à base de Fer de façon homogène ou inhomogène, mais toujours pour des états magnétiques à faible TN et faibles moments en accord avec des descriptions itinérantes à faibles corrélations. Pourtant un nouveau composé au Sélénium est venu remettre en cause ces conclusions en présentant une apparente coexistence homogène entre une forte supraconductivité macroscopique (Tc ≈ 30K) et un très fort antiferromagnétisme (TN ≈ 600K, moments magnétiques de valeur élevée de 3.3µB). Cette observation suggère donc une description ici plutôt en terme d'isolants de Mott contrairement aux autres supraconducteurs à base de Fer. Nos mesures RMN permettent de montrer en fait l'existence d'une séparation de phase et de statuer sur la stœchiométrie et les propriétés électroniques des différentes phases, pour finalement réconcilier ce composé et les autres familles. Deuxième exception : dans la famille archétype BaFe₂As₂, tous les dopages sur site Fer ou Arsenic ou même l'application de pression mènent à la supraconductivité, sauf dans le cas du dopage au Manganèse ou au Chrome en site Fer, qui ne provoquent pas l'apparition de la supraconductivité. Nos mesures RMN nous ont permis de sonder la nature de la transition magnétique, mais aussi l'état métallique de ces composés substitués. Nous montrons en particulier que le trou supplémentaire du Manganèse substitué à la place du Fer reste en fait localisé sur son site et se manifeste alors par un moment magnétique localisé. Cette étude du dopage par le Manganèse ouvre la voie à l'idée d'utiliser le Manganèse en faible concentration comme source de moments localisés qui polarisent magnétiquement leur environnement. Cette polarisation permet en effet de caractériser la nature même des corrélations de spin. Nous avons donc utilisé la RMN ainsi que la magnétométrie-SQUID pour mesurer cette polarisation dans des composés supraconducteurs pour sonder les corrélations de spins de ces systèmes. Nous concluons que ces corrélations sont plutôt faibles et indépendantes de la température dans les composés dopés en électrons.

Der erste Teil dieser Arbeit ist dem Kondogittermodell gewidmet. Für ein Elektron, das in einen ferromagnetisch gesättigten Hintergrund aus lokalen Spinmomenten eingebracht wird (ferromagnetisches Polaron), wird die stationäre Schrödingergleichung gelöst und das vollständige Eigenwertspektrum im endlichen und unendlichen Gitter abgeleitet. Danach wird die zeitabhängige Schrödingergleichung für beliebige Anfangsbedingungen gelöst und eine detaillierte Analyse des Down-Elektron-Zerfalls vorgenommen. Für endliche Bandfüllungen wird im Anschluss das magnetische Grundzustandsphasendiagramm mit Hilfe einer Molekularfeldtheorie bestimmt. Der Einfluss von Verdünnung/Unordnung im lokalen Momentensystem auf die auftretenden Phasen wird analysiert. Im zweiten Teil der Arbeit wird das Hubbardmodell untersucht. Für dieses wird mit Hilfe einer modifizierten Störungstheorie (englisch: modified perturbation theory, MPT) eine wellenzahlabhängige (nicht-lokale) Selbstenergie abgeleitet, die sowohl für schwache als auch für starke Coulombwechselwirkungen gute Ergebnisse liefert. Mit dieser werden dann Spektraldichten und Quasiteilchenzustandsdichten berechnet, wobei insbesondere die nicht-lokalen Korrelationseffekte im Fokus stehen. Daneben werden Ergebnisse für die optische Leitfähigkeit, die in einer renormierten diagrammatischen Ein-Schleifen-Näherung berechnet wurden, besprochen. Es wird dann gezeigt, dass nur unter Beachtung der nicht-lokalen Korrelationseffekte ein ferromagnetisches Phasendiagramm konstruiert werden kann, das in Einklang mit dem Mermin-Wagner-Theorem steht.
The first part of this work deals with the Kondo-lattice model. The stationary Schrödinger equation is solved for the case of one electron in a ferromagnetically saturated local moment system (the magnetic polaron). The complete eigensystem is derived for the finite and infinite lattice. The time-dependent Schrödinger equation is then solved for arbitrary initial conditions and a detailed analysis of the down-electron decay dynamics is given. For finite band occupations the magnetic ground-state phase diagram is constructed within a mean-field theory. The effect of disorder/dilution in the local moment system on the phase diagram is discussed. The second part concentrates on the investigation of the Hubbard model. A nonlocal self-energy is derived within a modified perturbation theory that interpolates between weak and strong Coulomb repulsion. Results for the spectral density and quasiparticle density of states are shown with special attention to the effects of nonlocal correlations. Results for the optical conductivity within a renormalized one-loop approximation are also discussed. The main result of this section is the importance of nonlocal correlations for the fulfillment of the Mermin-Wagner theorem. A phase diagram that shows regions of ferromagnetic order is calculated for the simple cubic lattice.

Etude théorique de la réactivité photochimique mono- et poly moléculaire des états de Rydberg infèrieurs de NH::(3), H::(2)O, CH::(4), alkylamines, alcools, radicaux méthyle, éthyle et ammonium de petits agrégats de NH::(3) ET NH::(3)-H::(2)O, de la photocyclodimèrisation de C::(2)H::(4), de l'extinction de l'état singulet excité de H::(2) par H::(2) à l'état fondamental, de la solvatation du radical NH::(4) dans un état de Rydberg par NH::(3), de l'interaction de H::(2) et HE avec NH::(3) excité, par la détermination des surfaces d'énergie potentielle par des méthodes ab initio quantitatives et des diagrammes de corrélation qualitatifs étendus aux états de Rydberg, en réunissant les différents concepts contenus dans les diagrammes de corrélation de l'atome unifié, dans le diagramme de Woodward Hoffmann, dans les règles de "topicité" et le concept de "rydbergnisation".

碩士
國立高雄大學
土木與環境工程學系碩士班
97
This study explored the application of 3D-Digital Image Correlation（3D-DIC） method to establish Forming Limit Diagram（FLD）. FLD can be established by ball punch deformation test. Grid method is usually used to measure the strain in this test. However, the precision of this method is not good enough and its process is complicated. DIC method is a non-contact measurement technique. It provides accurate measurements of the full field strain distribution, and the process of this method is simple. In this study, the 3D-DIC method, in which only one camera is used, is applied in the ball punch deformation test and the advantage and disadvantage of this method and the grid method are compared. 　　According to the result of the experiments, 3D-DIC method can measure the major strain and the minor strain successfully in the ball punch deformation test. Moreover, the 3D-DIC method is easier and more accurate than grid test. 　　A numerical simulation is also carried out in this research. The major and minor strains obtained from the simulation are different from that measured by DIC and grid method. But the tendency of the strain path is very similar to that from DIC. And this strain path can not be measured by the grid method. As a result, the 3D-DIC method has a great potential in the ball punch deformation test.

The Ellisras Basin, with huge coal resources, is fault-bounded along its southern and northern margins and is a graben-type deposit. The study area is situated in the south-western part of the Limpopo Province of the Republic of South Africa and is geologically located in the Ellisras Basin. In this area the basin is influenced by three major fault zones, the Eenzaamheid Fault delineating its southern limit, the Zoetfontein Fault near its northern limit and the Daarby Fault, with a down-throw of approximately 350 m towards the north-east. Sedimentological facies changes also influence the continuity of the coal zones, with deterioration in coal development. The exploration project was a collaboration between two of the large role players in the South African coal mining industry Sasol and Exxaro, for the purpose of identifying whether the coal in the Ellisras Basin could be used for gasification purposes in the Sasol process, and that enough resources exist on the farms on which the two companies have the exploration rights.. The prospecting method used at the Project area, situated 50 kilometer west of the town of Lephalale in the Limpopo Province of South Africa, comprises the drilling of cored exploration boreholes on a random spacing of ± 1 000 m x 1 000 m, together with infill percussion drilling. The use of slimline geophysical methods to log lithologies is a technique which has been used extensively in the mining industry over a number of years. At the Project area the correlation between the measured densities derived from the traditional method of air and water measurement and those derived from Vectar processed derived densities from geophysical logging is better than 95%. As a method of “fingerprinting” the various coal zones and samples it was decided to calculate the distribution of relative densities in the chosen geological intersection. The data was then used to portray geophysically derived relative density cumulative distribution line diagrams (GDCDD) of the various lithotypes on either a sample-by-sample or zone-by-zone basis. Using the classification method proposed, the various coal seams and zones can be correlated to a high degree and discrepancies easily identified. The lateral correlation between lithologies can be accurately described and substantiated, and this would convince a Competent Person that the method proposed is invaluable in classifying coal resources in the coal basins.
Thesis (PhD)--University of Pretoria, 2014.
lk2014
Geology
PhD
Unrestricted

Text in Afrikaans
Due to the radical reform in mathematics education worldwide, the mathematics curriculum underwent dramatic changes in order to meet the new objectives in mathematics. This has placed a huge responsibility on curriculum compilers and the authors of mathematics textbooks and mathematics teachers to enhance the cognitive development of learners. This study takes the view that: What happens in the class is what you get. Based on the above statement, the foundation of mathematics teaching, namely the mathematics curriculum, the mathematics textbook and the teacher’s instruction in the teaching venue were scrutinised. During a diagnostic examination of teachers’ interpretation, knowledge and application of the mathematics curriculum and the content of mathematics textbooks on the East Rand, the following problems regarding mathematics teaching emerged: The most important finding of TIMMS is that the differences in performance in mathematics between different countries can be linked to the way teachers interpret and present the content of mathematics. Research has revealed that the interaction of teachers with curriculum content follow a dynamic and constructive application instead of direct application based on the mathematics curriculum. Teachers often change the prescriptions and order of content in the mathematics curriculum to suit their teaching style, knowledge and previous experience. Consequently, align application of mathematical concepts and skills does not take place and this creates a gap in learners’ cognitive development. It also leaves a gap in the application of the Type 5 cognitive development tasks in mathematics which enable a verifying deductive application of concepts. The action research created a structure which could meet this need. Authors of mathematics textbooks present their own vision, interpretation and style in mathematics textbooks, which influences the order of mathematics content and concepts. The result is that mathematics content and concepts are at times not aligned with representations in the mathematics curriculum and objectives are therefore not reached. The different interpretations of mathematics textbooks by teachers differ greatly and these differences place great pressure on teachers to decide how the mathematics textbook will be used in the teaching venue. In this study a mathematics textbook profile and a task analysis were formulated in the cause of action research which will enable teachers to make a professional analysis which they can use. Because a variety of mathematics textbooks are selected for use in schools, teachers assume that these approved mathematics textbooks focus on the curriculum. They therefore slavishly follow the mathematics textbooks without consulting the mathematics curriculum. Shortcomings in mathematics textbooks and teachers’ own interpretation of mathematics content leave a big gap in their own alignment of mathematics teaching. To satisfy this need, an assessment profile and an methodology for alignment are provided to enable teachers to monitor the curriculum alignment presentation of concepts and skills.
As gevolg van die radikale hervorming in wiskunde-onderrig wêreldwyd het die wiskundekurrikulum dramatiese veranderings ondergaan ten einde die nuwe doelstellings in wiskunde te bereik. Dit het enorme verantwoordelikheid geplaas op kurrikulumsamestellers en outeurs van wiskundehandboeke en wiskunde-onderwysers om die kognitiewe ontwikkeling van leerders te bevorder. In hierdie studie is van die volgende standpunt uitgegaan: What happens in the class is what you get. Derhalwe is die fondasie van wiskunde-onderrig, naamlik die wiskundekurrikulum, wiskundehandboek en die onderwyser se instruksies in die klaskamer ondersoek. In `n diagnostiese ontleding van onderwysers se interpretasie, kennis en toepassing van die wiskundekurrikulum en die wiskundehandboekinhoude aan die Oos-Rand het die volgende probleme in verband met wiskunde-onderrig na vore gekom: Die belangrikste bevinding van TIMMS is dat die verskille in wiskundeprestasie tussen lande verband hou met die wyse waarop onderwysers die wiskudekurrikuluminhoude interpreteer en aanbied. Navorsing toon dat die interaksie van onderwysers met kurrikulummateriaal op ʼn dinamiese en konstruktiewe toepassing geskied in plaas van direkte toepassing vanuit die wiskundekurrikulum. Onderwysers verander dikwels die wiskundekurrikulum se voorskrifte en volgorde van inhoude om by hulle onderrigstyl, kennis en vorige ervarings te pas. Die gevolg is dat geen inlyntoepassing van wiskundebegrippe en vaardighede plaasvind nie en dit laat ʼn leemte in leerders se kognitiewe ontwikkeling. Verder laat dit ʼn leemte in die toepassing van die 5-tipe kognitiewe ontwikkelingstake in wiskunde wat ʼn verifiërend deduktiewe toepassing van begrippe bewerkstellig. In die aksienavorsing is ʼn struktuur geskep wat in hierdie behoefte voorsien. Outeurs van wiskundehandboeke het ʼn eie visie, interpretasie en styl wat hulle in wiskundehandboeke aanbied. Dit het ʼn invloed op die volgorde van wiskunde-inhoude en begrippe en gevolglik is wiskunde-inhoude en -begrippe soms nie inlyn geplaas met voorstellings van die wiskundekurrikulum nie, en word doelstellings nie bereik nie. Onderwysers se verskillende interpretasies van wiskundehandboekinhoude verskil radikaal van mekaar en plaas gevolglik groot druk op onderwysers om ʼn keuse te maak wat betref die gebruik van ʼn wiskundehandboek vir gebruik in die klaskamer. In die studie is ʼn wiskundehandboekprofiel en ʼn taakontleding tydens aksienavorsing geformuleer wat onderwysers in staat sal stel om ʼn professionele ontleding te maak vir gebruik. As gevolg van die verskeidenheid wiskundehandboeke wat gekeur word vir gebruik in skole neem onderwysers aan dat hierdie gekeurde wiskundehandboeke op die kurrikulum gerig is. Gevolglik word wiskundehandboeke slaafs nagevolg sonder om die wiskundekurrikulum te raadpleeg. Tekortkominge in wiskundehandboeke en die eie interpretasie van wiskundeinhoude deur onderwysers laat ʼn groot leemte in hul eie inlynwiskunde-onderrig. Om te voorsien in hierdie behoefte is ʼn assesseringsprofiel en ʼn inlynmetodiek saamgestel om onderwysers in staat te stel om die inlynaanbieding van begrippe en vaardighede te monitor.
Curriculum and Instructional Studies
D. Ed. (Didaktiek)