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The first part of this thesis examines and compares the separate closure formalisms of Wyld and Martin, Siggia, and Rose (MSR). The simplicity of Wyld’s perturbation scheme is offset by an incorrect renormalisation, this contrasts with the formally exact analysis of MSR. The work here shows that a slight change in Wyld’s renormalisation keeps the main results intact and, in doing so, demonstrates that this formalism is equivalent to MSR. The remainder of the thesis is concerned with turbulent dissipation. A numerical solution of the Local Energy Transfer theory, or LET, is reworked and extended to compute decaying and forced turbulence at large Reynolds numbers. Using this numerical simulation, the phenomenon of turbulent dissipation is investigated. In order to use decaying turbulence to study the turbulent dissipation rate as a function of Reynolds number, it is necessary to choose an appropriate time with which a measurement can be taken. Using phenomenological arguments of the evolution of a turbulent fluid, criteria for establishing such a time are developed. An important study in turbulence is the dissipation rate in the limit of vanishing viscosity, also known as the dissipation anomaly. This thesis derives an equation for the dissipation rate from the spectral energy balance equation. Using the LET computation for both decaying and forced turbulence, results are obtained that can be used along with the equation to study the mechanisms behind the dissipation anomaly. It is found that there is a difference in the behaviour of the normalised dissipation rate between decaying and forced turbulence and, for both cases, it is largely controlled by the energy flux.

<p> The need for higher bandwidth and people's desire to be "always connected" have spurred a new era of silicon photonics. The traditional integrated electrical transmission lines have been an obstacle preventing ultra high speed communication. Using monolithic chips of integrated optoelectronic circuits from silicon provides an economic way to realize Tetra Byte/Second bandwidth in a variety of areas such as "fiber to the home" and the buses linking chips inside computer.</p> <p> The heart of such optoelectronics-silicon laser-is still in pursuit. One of the most promising approaches is the erbium doped silicon nanocrystals embedded in silica system. External photon or hot electrons injection excites the silicon nanocrystals, which then transfer their energies to nearby erbium ions to emit light at 1.55 μm wavelength range.</p> <p> In this thesis, we investigate the effects of cavity and electric field on energy transfer from Si nanocrystals (Si-nc's) to Er ions, and simulate material gain in such systems. Our results show that microcavity can enhance the Forster energy transfer and material gain, reducing the requirements for Si-nc pumping. The electric field will hinder the radiation decay of Si-nc, but we have to further explore the tunneling mechanism before concluding the overall effect of electric field. Some future work needs to be done, which will shine some light on the design of the silicon laser.</p> / Thesis / Master of Applied Science (MASc)

To date, there exists no complete, computationally efficient, physics-based model to compute the radar backscatter from forest canopies. Several models attempt to predict the backscatter coefficient for random forest canopies by using the Vector Radiative Transfer (VRT) Theory with success, however, these models often rely on purely time-harmonic formulations and approximations to integrals. Forms of VRT models have recently been developed which account for a Gaussian pulse incident waveform, however, these models often rely heavily on very specific and obfuscated approximations to solve the associated integrals. This thesis attempts to resolve this problem by outlining a method by which existing, proven, time harmonic solutions to the VRT equation can be modified to account for arbitrary pulse waveforms through simple path delay method. These techniques lend physical insight into the actual scattering mechanisms behind the returned waveform, as well as offer explanations for why approximations of previous authors' break down in certain regions. Furthermore, these radiative transfer solutions can be reformulated into a convolutional model which is capable of quickly and accurately predicting the radar return of random volumes. A brief overview of radiative transfer theory as it applies to remote sensing is also given. / Master of Science

Le test de rotation mentale (TRM) est robuste pour faire émerger une grande différence de sexe en faveur des hommes. Il existe un stéréotype, communément admis, de moins bonnes performances des femmes en aptitude spatiale. Deux théories explicatives cohabitent. La première, biologique, est liée à une masculinisation du cerveau des garçons sous l'action des androgènes durant la vie fœtale. Dans cette hypothèse, et en raison d'un transfert d'hormones supposé durant la vie intra-utérine, les femmes qui ont un cojumeau doivent avoir des performances meilleures que celles ayant une cojumelle (Vuoksimaa et al., 2010). L'autre hypothèse, que nous défendons, suppose que les différences de sexe au TRM peuvent être socialement construites ou activées par des éléments du Contexte évaluatif et ceci quel que soient les compétences des personnes. Nous avons, pour la première fois dans une étude gémellaire, confronté ces deux hypothèses. Des paires de jumeaux jeunes adultes dizygotes de même sexe (DZMS), 23 paires d'hommes et 34 paires de femmes, et de sexe différent (DZSD), 62 paires, ont passé un TRM informatisé dans deux conditions expérimentales où l'exactitude des réponses et les temps de réponse sont enregistrés. Dans une condition, les consignes du test rendent la situation de comparaison au cojumeau possible (CSP) : « vous et votre jumeau ferez le même test aujourd'hui », dans l'autre condition (CSI) la comparaison est rendue improbable : « vous et votre jumeau ferez des tâches différentes ». Nos résultats n'accréditent pas la théorie biologique et sont en faveur d'une explication en termes d'interférence du stéréotype. / The mental rotation test (MRT) is the most robust test revealing that men outperform women. Two major causes have been proposed for explaining the origin of this difference. The first focused on brain masculinization under the action of androgen during the fetal development. Vuoksimaa et al., (2010) showed that dizygotic opposite-sex female have greater performances than dizygotic same-sex female. For the second hypothesis, sex difference is mainly due to social regulation factors and stereotype threat interaction. We test here this second hypothesis. In a twin design we tested, for the first time, these two causal explanations. Same-sex dizygotic young adult pairs (23 pairs of males and 34 pairs of females), and opposite-sex dizygotic pairs (62 pairs) took a computerized MRT in two experimental co-action conditions. In the first condition, the experimental situation make the co-twin comparison possible (CSP): “you and your co-twin do the same test today”, and in the other experimental condition called, improbable comparison situation (CSI), they are told that: “you and your co-twin do different test today”. Accuracy and responses time where analyzed. Our results do not support the biological model but, in contrary, support the social regulation and stereotype threat model.

Die Off-Axis-Elektronenholographie ist eine interferometrische Methode zur experimentellen Bestimmung von relativen Phasenschiebungen einer Elektronenwelle. Der Zugang zu diesen Phasenschiebungen ermöglicht z.B. die Bestimmung von intrinsischen elektrischen und magnetischen Feldern eines Objektes im Nanometerbereich. Für eine quantitative Interpretation der Resultate ist die Kenntnis des Rauschens der holographisch rekonstruierten Größen von hoher Bedeutung. In dieser Arbeit wird ein allgemeiner Formalismus abgeleitet, der den Rauschtransfer vom detektierten Hologramm in die rekonstruierten Amplituden- und Phasenbilder beschreibt. Anhand zielgerichteter Experimente wird dieser Formalismus unter Berücksichtigung von gemessenen Rauscheigenschaften des Detektors verifiziert. Im Zuge dessen wird eine experimentelle Methode entwickelt, die es erlaubt, durch Serienaufnahmen und Mittelungsprozeduren das Signal-zu-Rauschverhältnis in den holographischen Resultaten bei gleichbleibender Ortsauflösung erheblich zu verbessern. Daran knüpft sich eine Vielzahl von Anwendungen an, welche in dieser Arbeit in Auszügen aufgeführt werden. Die Grundlage für all diese Experimente besteht in den Welleneigenschaften des Elektrons, welche in der Interferenzfähigkeit (Kohärenz) des Elektrons zum Ausdruck kommen. Elektronen, welche unelastisch an einem Objekt streuen, verlieren diese Eigenschaft und es stellt sich die Frage, ob aus diesem Verlust zusätzliche Informationen über den Streuprozess bzw. über das Objekt selbst gewonnen werden können. Eine Größe, die neben der Intensität auch die Kohärenz der Elektronen beschreibt, ist die reduzierte Dichtematrix. Das motiviert, die Methode der Off-Axis-Elektronenholographie in der Sprache der Dichtematrizen zu formulieren und eine allgemeine Übertragungstheorie für ein holographiefähiges Transmissionselektronenmikroskop abzuleiten. Diese Theorie umfasst alle bisher bekannten Phänomene im Rahmen der Elektronenholographie und bietet darüber hinaus neue instrumentelle Ansätze zur Optimierung des Signal-zu-Rausch-Verhältnisses und zur Überwindung auflösungsbegrenzender Aberrationen. Vor diesem Hintergrund wird weiterhin die Kohärenz von Elektronen mittels energiegefilterter Off-Axis-Elektronenholographie untersucht, welche unelastisch an Siliziumoberflächen streuen und charakteristische Oberflächenplasmonen anregen. Für die Interpretation der Resultate werden zwei Modelle für die Dekohärenz des Elektrons infolge der Wechselwirkung mit einer Objektoberfläche entwickelt und unter Berücksichtigung der Aberrationen des Energiefilters mit dem Experiment verglichen. / Off-axis electron holography provides access to the relative phase shift of an electron wave and allows the experimental determination of intrinsic electric and magnetic fields within an object at nanometre scale. A quantitative interpretation of the results requires the knowledge about the noise in the reconstructed data. In this work, a general formalism is derived describing the transfer of noise from an experimental hologram into reconstructed amplitude and phase images. Concerted experiments verify this formalism under consideration of measured noise properties of the detector. In this frame, a method based on series acquisition and averaging is developed to improve significantly the signal-to-noise ratio of the reconstructed amplitude and phase images at constant spatial resolution. The usefulnes of this method is demonstrated by selected experimental examples from the materials sciences. The capability to show interference, i.e. to be coherent, is a consequence of the electron's wave nature and provides the fundament for all applications of electron holography. By inelastic interaction with the object, the electron loses coherence and the question comes up, whether this loss mechanism contains additional information about the scattering process or even about the object itself. The reduced density matrix is introduced as a suitable quantity describing both intensity and coherence of scattered electrons. That motivates to formulate off-axis electron holography in the language of density matrices and to derive a general transfer theory for this quantity in a holography-dedicated transmission electron microscope. This theory reproduces all known phenomena related to off-axis electron holography and provides new instrumental approaches to improve the signal-to-noise ratio and to overcome resolution limiting aberrations. In this context, the coherence of electrons, which are inelastically scattered by silicon surfaces and have excited characteristic surface plasmons, is investigated by energy-filtered electron holography. For the interpretation of the experimental results, two models are developed for the decoherence of the electron by interaction with an object surface and are compared to the experiment under consideration of the aberrations of the energy-filter.

Die Off-Axis-Elektronenholographie ist eine interferometrische Methode zur experimentellen Bestimmung von relativen Phasenschiebungen einer Elektronenwelle. Der Zugang zu diesen Phasenschiebungen ermöglicht z.B. die Bestimmung von intrinsischen elektrischen und magnetischen Feldern eines Objektes im Nanometerbereich. Für eine quantitative Interpretation der Resultate ist die Kenntnis des Rauschens der holographisch rekonstruierten Größen von hoher Bedeutung. In dieser Arbeit wird ein allgemeiner Formalismus abgeleitet, der den Rauschtransfer vom detektierten Hologramm in die rekonstruierten Amplituden- und Phasenbilder beschreibt. Anhand zielgerichteter Experimente wird dieser Formalismus unter Berücksichtigung von gemessenen Rauscheigenschaften des Detektors verifiziert. Im Zuge dessen wird eine experimentelle Methode entwickelt, die es erlaubt, durch Serienaufnahmen und Mittelungsprozeduren das Signal-zu-Rauschverhältnis in den holographischen Resultaten bei gleichbleibender Ortsauflösung erheblich zu verbessern. Daran knüpft sich eine Vielzahl von Anwendungen an, welche in dieser Arbeit in Auszügen aufgeführt werden. Die Grundlage für all diese Experimente besteht in den Welleneigenschaften des Elektrons, welche in der Interferenzfähigkeit (Kohärenz) des Elektrons zum Ausdruck kommen. Elektronen, welche unelastisch an einem Objekt streuen, verlieren diese Eigenschaft und es stellt sich die Frage, ob aus diesem Verlust zusätzliche Informationen über den Streuprozess bzw. über das Objekt selbst gewonnen werden können. Eine Größe, die neben der Intensität auch die Kohärenz der Elektronen beschreibt, ist die reduzierte Dichtematrix. Das motiviert, die Methode der Off-Axis-Elektronenholographie in der Sprache der Dichtematrizen zu formulieren und eine allgemeine Übertragungstheorie für ein holographiefähiges Transmissionselektronenmikroskop abzuleiten. Diese Theorie umfasst alle bisher bekannten Phänomene im Rahmen der Elektronenholographie und bietet darüber hinaus neue instrumentelle Ansätze zur Optimierung des Signal-zu-Rausch-Verhältnisses und zur Überwindung auflösungsbegrenzender Aberrationen. Vor diesem Hintergrund wird weiterhin die Kohärenz von Elektronen mittels energiegefilterter Off-Axis-Elektronenholographie untersucht, welche unelastisch an Siliziumoberflächen streuen und charakteristische Oberflächenplasmonen anregen. Für die Interpretation der Resultate werden zwei Modelle für die Dekohärenz des Elektrons infolge der Wechselwirkung mit einer Objektoberfläche entwickelt und unter Berücksichtigung der Aberrationen des Energiefilters mit dem Experiment verglichen. / Off-axis electron holography provides access to the relative phase shift of an electron wave and allows the experimental determination of intrinsic electric and magnetic fields within an object at nanometre scale. A quantitative interpretation of the results requires the knowledge about the noise in the reconstructed data. In this work, a general formalism is derived describing the transfer of noise from an experimental hologram into reconstructed amplitude and phase images. Concerted experiments verify this formalism under consideration of measured noise properties of the detector. In this frame, a method based on series acquisition and averaging is developed to improve significantly the signal-to-noise ratio of the reconstructed amplitude and phase images at constant spatial resolution. The usefulnes of this method is demonstrated by selected experimental examples from the materials sciences. The capability to show interference, i.e. to be coherent, is a consequence of the electron's wave nature and provides the fundament for all applications of electron holography. By inelastic interaction with the object, the electron loses coherence and the question comes up, whether this loss mechanism contains additional information about the scattering process or even about the object itself. The reduced density matrix is introduced as a suitable quantity describing both intensity and coherence of scattered electrons. That motivates to formulate off-axis electron holography in the language of density matrices and to derive a general transfer theory for this quantity in a holography-dedicated transmission electron microscope. This theory reproduces all known phenomena related to off-axis electron holography and provides new instrumental approaches to improve the signal-to-noise ratio and to overcome resolution limiting aberrations. In this context, the coherence of electrons, which are inelastically scattered by silicon surfaces and have excited characteristic surface plasmons, is investigated by energy-filtered electron holography. For the interpretation of the experimental results, two models are developed for the decoherence of the electron by interaction with an object surface and are compared to the experiment under consideration of the aberrations of the energy-filter.

The unprecedented turbulence and uncertainty experienced in global economic and financial markets because of the 'credit crunch' has had a damaging impact on consumer confidence. Trust and credibility have been eroded as many customers feel let down by the banks suggesting the need for banks to rebuild constructive dialogue and long-term, meaningful relationships with their customers again. Though financial service, in this case, is considered a utilitarian service, based on the fact that money is needed to support people‘s daily activities, the present state of financial service has suggested the need for banks to appeal to consumers‘ emotions with the aim of improving their reputation. Also, the competition within the industry also could suggest the need to adopt an emotionally appealing advertisement strategy as emotions are known to play an influential role in building robust brand preference. This study builds on the communication theory, meaning transfer theory and consumer involvement theory, to understand the messages the banks are sending out and to elicit consumers‘ emotional reaction. One thousand, two hundred and seventy-four UK bank advertisements in nine national newspapers were content-analysed to identify the emotional appeals presented by the banks. The perception of these appeals and their associated meanings were sought through semi-structured interviews with 33 participants in London and Luton. The results of the analysis indicated that UK Banks are utilising emotional appeal in their advertisements to reach out to the consumers to convince them to upgrade their account, to open an additional account or switch their account. The most predominantly used appeals were relief and relaxation followed by excitement and happiness or satisfaction with the bank, and finally, security and adventure. However, variations were found in different financial products that employed emotional appeals. It was found that high-involvement products such as mortgages and loans used fewer emotional appeals. Both bank groups - high street banks, including the big four (Barclays, HSBC, Lloyds and RBS) and non-high street banks, such as the new entrants, supermarket brands, and online banks were using emotional appeals. However, it is acknowledged that the communication strategies between these banks could be different as the non-high street banks are more likely to repeat and publish the same messages across many newspapers, instead of publishing different emotionally appealing advertisements. Though consumers acknowledged these emotional appeals in the advertisements, they were more concerned about their relationship with the banks as they don‘t rely on advertisements to make a financial decision. Rather, recommendations from families, friends and associates and also branch location are more important when deciding on which bank to choose. The lack of congruency between financial services and emotional appeals in advertisements is also observed as customers are more likely to be persuaded by rational appeals however this study has not completely ruled out emotional appeals in bank advertisements as the use of both types of appeals is recommended. The study provides important theoretical and managerial contributions to understanding how the consumers understand meaning-embedded advertisements produced by the banks. Managers will be able to consider the implications of advertisements in enhancing their brand equity and building relationships with customers in anticipation that, by word of the mouth and established relationship, their bank‘s reputation will be enhanced. Limitations of the study and opportunities for future research are identified.