The ~ 73 ka ‘super-eruption’ of the Toba caldera in Sumatra is the largest known eruption of the Quaternary. The products of this eruption, the Youngest Toba Tuff (YTT), have been implicated in global and regional climate deterioration with widespread ecological effects. In this thesis I study the YTT co-ignimbrite ashfall, in particular the mechanisms of transport, sedimentation and preservation of ash deposits. I use distal marine and terrestrial ash sediments: a) to estimate the volume of YTT ash fallout; b) to quantify variability in the geochemistry of YTT ash; c) to assess the reliability of YTT ash as a chronostratigraphic marker; and d) to determine local influences on the reworking of YTT ash deposits. Following the introductory chapters, I address topics a) and b) through detailed investigations of published physical and chemical evidence. Chapter three shows that particle size and sediment thickness do not decline exponentially with distance from the eruption vent, highlighting the limitations of current methods of volume estimation for co-ignimbrite super-eruptions. Chapter four analyses geochemical variation in 72 YTT samples, and reveals the signatures of magma chamber zonation and post-depositional alteration. I address topics c) and d) through fieldwork in six locations, and detailed analysis of ash samples from a wide variety of local depositional environments. Chapter five uses high-resolution stratigraphic analysis of the YTT layer in the Son Valley, India, to show that variable deposition and sediment reworking may compromise the reliability of the ash layer as an isochronous marker for interpreting archaeological sequences. Chapter six combines a new understanding of the mechanisms of reworking, using new data on microscopic characteristics of reworked ash at four sites in Malaysia to demonstrate the necessity of accounting for reworking in palaeoenvironmental reconstructions. I conclude that accurate analyses of distal ash deposits can reliably determine the chemical properties of the YTT eruption, and that a detailed understanding of deposition and reworking processes is essential to inference of the environmental impacts of super-eruptions.

The objective of this research is to develop suitable models to simulate and analyse Electrical Vehicle (EV) power-trains to identify and improve some of the deficiencies of EVs and investigate new system architectures. Although some electro-chemical batteries improvements have lately been achieved in specific-energy, the power density is still low. Therefore, an efficient, cost-effective and high power density support unit could facilitate EV competitiveness compared to conventional internal combustion engine powered vehicles in the near future. The Na-Ni-Cl2, or ZEBRA battery as it is most commonly known, has good energy and power densities; it is very promising electro-chemical battery candidate for EV's. The thesis presents a detail simulation model for the ZEBRA technology and investigates its application in an EV power-train with regard to state-of-charge and voltage transients. Unlike other battery systems, the ZEBRA technology can sustain about 5-10% of failed cells. While this is advantageous in single series string or single battery operation it is problematic when higher numbers of batteries are connected in parallel. The simulation model is used to investigate faulted operation of parallel battery configurations. A non-linear capacitance versus voltage function is implemented for the supercapacitor model which yields good energy and terminal voltage predictions when the supercapacitor is cycled over dynamic regimes common to EV applications. A thermal model is also included. Multiple energy source systems are modelled and studied in the form of an energy dense ZEBRA battery connected in parallel with a power dense supercapacitor system. The combination is shown to increase available power, reduce the maximum power demanded from the battery and decrease battery internal power loss. Consequently, battery life would be increased and more energy would be recovered from regenerative braking, enhancing the energy conversion efficiency of the power-train.A combination of ICE and ZEBRA battery is implemented as a range extender for London taxi driving from Manchester to London. The hybridisation ratio of the system is discussed and applied to fulfil the requirement with minimum emissions. This study offers a suitable model for different energy sources, and then optimises the vehicle energy storage combination to realize its full potential. The developed model is used to assess different energy source combinations in order to achieve an energy efficient combination that provides an improved vehicle performance, and, importantly, to understand the energy source interconnection issues in terms of energy flow and circuit transients.

The present study compared the career development concerns and other vocationally relevant variables of employees of organizations who have and have not engaged in downsizing within a one year timeframe. The sample consisted of 162 participants, 72 layoff survivors (those who remained in an organization after its downsizing) and 92 non-survivors (employees in organizations who have not downsized within 12 months). Significant results were found that differentiated the career related experiences of participants in the survivors group, survivors from non-survivors, and participants in general regardless of survivorship status. In general, results indicated that non-survivors reported greater job satisfaction and job security than layoff survivors, that being married with children may increase job satisfaction, and social support may buffer the grief reactions that survivors have to the loss of their co-worker friends. Furthermore, Super's age-associated stages within the Life-Span, Life-Space Theory were moderately upheld in the sample, especially for the Exploration stage. However, younger workers demonstrated more Maintenance concerns that would be predicted by the theory. A discussion of the relevant literature is included as well as possible explanations of the results, small sample size, and implications for future research.

Magíster en Ciencias, Mención Computación / Ingeniero Civil en Computación / En esta tesis se aborda el problema de analizar el rendimiento de cuatro algoritmos de super-resolución multi-imagen cuando éstos son usados para recuperar imágenes astronómicas de alta resolución. Super-resolución multi-imagen es el nombre dado a los procesos que usan un conjunto de imágenes de baja resolución de una misma escena para obtener una nueva imagen con mayor resolución espacial, además de menos desenfoque y ruido, que cualquiera de las imágenes utilizadas como input. Estos algoritmos funcionan mediante la minimización de una función de costo, donde un prior es incluido para regularizar el proceso de reconstrucción, usando para ello un procedimiento de optimización basado en el cálculo del gradiente. Cada uno de los cuatro algoritmos desarrollados corresponde a una de las cuatro posibles combinaciones entre dos priors (Laplaciano y gradiente) para la función de costo y dos mecanismos para calcular su gradiente (la expresión analítica de dicho gradiente y la aproximación de Zomet). El principal objetivo de esta investigación consiste en estudiar el comportamiento del rendimiento de estos algoritmos en función de la Razón Señal-a-Ruido (SNR) de la imágenes de baja resolución empleadas como input en el proceso de reconstrucción. Para lograr este objetivo se requiere hacer uso de simulaciones, ya que se necesitan conjuntos de imágenes de baja resolución caracterizados por distintos valores de SNR para testear el funcionamiento de los cuatro algoritmos. Las imágenes simuladas fueron obtenidas usando dos herramientas de simulación, una basada en la replicación del proceso mediante el cual una imagen es adquirida por un dispositivo y que se conoce como Modelo de Observación de Imágenes (IOM), y otra basada en un enfoque de Monte Carlo y cuyo nombre es PhoSim. Considerando un rango de siete valores de SNR, muestreados en intervalos regulares entre 1 y 100 con una escala logarítmica, y usando un grupo de 100 templates de alta-resolución, se generaron 700 conjuntos, compuesto cada uno por 10 imágenes simuladas de baja resolución, utilizando para ello las dos herramientas de simulación previamente mencionadas. Luego, cada uno de los cuatro algoritmos fue empleado para reconstruir una imagen de alta resolución usando cada uno de estos conjuntos como input. El experimento descrito se llevó a cabo en dos instancias, primero usando registro afín para alinear las imágenes de baja resolución contenidas en cada conjunto utilizado como input, y luego utilizando registro cuadrático para cumplir dicha tarea. El rendimiento de los algoritmos fue evaluado, luego de realizar estos experimentos, usando como métricas el Peak de la Razón Señal-a-Ruido (PSNR) y el χ² reducido. De acuerdo a los resultados obtenidos, para cada uno de los algoritmos el PSNR aumenta a medida que la SNR crece, mientras que el χ² reducido se mantiene relativamente constante independientemente de la SNR. Los resultados correspondientes al PSNR sugieren que para valores pequeños de la SNR la aproximación de Zomet y el prior Laplaciano representan la mejor opción, mientras que para valores altos de la SNR la expresión analítica del gradiente junto al prior gradiente son la mejor opción, aunque, en este caso, por un margen estrecho. La magnitud de la disminución de rendimiento que se observa cuando los parámetros de registro y desenfoque son estimados es mayor cuando se usa PhoSim que cuando se usa el IOM. La utilización de diferentes procedimientos de registro no implicó variaciones significativas en el rendimiento de los cuatro algoritmos de super-resolución multi-imagen.

The effect of involvement with program context has long been an imperative factor in understanding advertising processing. However, contradictory theses and inconsistent findings demand better clarifications. This thesis bridges a gap between the key constructs of program intensity and product involvement in terms of TV advertising effects with the consideration of antecedents of program involvement. Following the “Cognitive Efficacy principle, the Wyer-Srull model, Limited Capacity Model and ELM model has been adopted to examine the theoretical frameworks of contextual and serial TV advertising position effects. With the emphasis on the concept of involvement, both situational and enduring involvement has been contemplated to explore the theoretical framework of TV advertising message processing. With the unit of analysis set at the advertised brand level, a naturalistic field study has been conducted to examine program intensity induced involvement (situational), product involvement (enduring) and audiences’ intrinsic involvement (enduring) effects on live TV advertising utilizing twelve years of Super Bowl broadcasting content analysis and survey data. The results have indicated that the advertisements subsequent to high intensity TV program contents are more likely to be memorized, yet it is moderated by product involvement. In other words the scoring segments would tend to have a positive effect on low involvement products and negative effect on high involvement products in terms of viewers’ memory. Additionally, the same effect patterns have been revealed on both high involvement (Fans) and low involvement (Non-Fans) viewers. However, the pattern of impact has not been witnessed on viewers’ attitude. The results have also validated serial position effects. The findings have revealed the dynamics created by program intensity and its interaction with product involvement on advertisement effects. The outcome also provided an in-depth understanding of TV ads positions for practical implications

Realtime Magnetic Resonance Imaging (MRI) is a method used for human anatomical study. MRIs give exceptionally detailed information about soft-tissue structures, such as tongues, that other current imaging techniques cannot achieve. However, the process requires special equipment and is expensive. Hence, it is not quite suitable for all patients. Speech diagrams show the side view positions of organs like the tongue, throat, and lip of a speaking or singing person. The process of making a speech diagram is like the semantic segmentation of an MRI, which focuses on the selected edge structure. Speech diagrams are easy to understand with a clear speech diagram of the tongue and inside mouth structure. However, it often requires manual annotation on the MRI machine by an expert in the field. By using machine learning methods, we achieved transferring images between MRI and speech diagrams in two directions. We first matched videos of speech diagram and tongue MRIs. Then we used various image processing methods and data augmentation methods to make the paired images easy to train. We built our network model inspired by different cross-domain image transfer methods and applied reference-based super-resolution methods—to generate high-resolution images. Thus, we can do the transferring work through our network instead of manually. Also, generated speech diagram can work as an intermediary part to be transferred to other medical images like computerized tomography (CT), since it is simpler in structure compared to an MRI. We conducted experiments using both the data from our database and other MRI video sources. We use multiple methods to do the evaluation and comparisons with several related methods show the superiority of our approach.

Recent development of super-resolution (SR) fluorescence microscopy techniques has provided a new tool for direct visualization of subcellular structures and their dynamics in cells. The homing of Hematopoietic stem/progenitor cells (HSPCs) to bone marrow is a multistep process that is initiated by tethering of HSPCs to endothelium and mediated by spatiotemporally organised ligand-receptor interactions of selectins expressed on endothelial cells to their ligands expressed on HSPCs which occurs against the shear stress exerted by blood flow. Although molecules and biological processes involved in this multi-step cellular interaction have been studied extensively, molecular mechanisms of the homing, in particular the nanoscale spatiotemporal behaviour of ligand-receptor interactions and their role in the cellular interaction, remain elusive. Using our new method of microfluidics-based super-resolution fluorescence imaging platform we can now characterize the correlation between both nanoscale ligand-receptor interactions and tethering/rolling of cells under external shear stress. We found that cell rolling on E-selectin caused significant reorganization of the nanoscale clustering behavior of CD44 and CD43, from a patchy clusters of ~ 200 nm in size to an elongated network-like structures where for PSGL-1 the clustering size did not change significantly as it was 85 nm and after cell rolling the PSGL-1 aggregated to one side or even exhibited an increase in the footprint. Furthermore, I have established the use of 3D SR images that indicated that the patchy clusters of CD44 localize to protruding structures of the cell surface. On the other hand, a significant amount of the network-like elongated CD44 clusters observed after the rolling were located in the close proximity to the E-selectin surface. The effect of the nanoscale reorganization of the clusters on the HSPC rolling over selectins is still an open question at this stage. Nevertheless, my results further demonstrate that this mechanical force-induced reorganisation is accompanied by a large structural reorganisation of actin cytoskeleton. Our microfluidics-based SR imaging also demonstrate an essential role of the nanoscale clustering of CD44 on stable rolling behaviours of cells. Our new experimental platform enhances understanding of the relationship between nanoscopic ligand-receptor interactions and macroscopic cellular interactions, providing a foundation for characterizing complicated HSPC homing

京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第21948号 / 理博第4526号 / 新制||理||1650(附属図書館) / 京都大学大学院理学研究科物理学・宇宙物理学専攻 / (主査)准教授 WENDELL Roger, 教授 中家 剛, 教授 鶴 剛 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DFAM

京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第22326号 / 医博第4567号 / 新制||医||1041(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 滝田 順子, 教授 小川 誠司, 教授 遊佐 宏介 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

京都大学 / 新制・課程博士 / 博士(理学) / 甲第23004号 / 理博第4681号 / 新制||理||1671(附属図書館) / 京都大学大学院理学研究科物理学・宇宙物理学専攻 / (主査)准教授 WENDELL Roger, 教授 中家 剛, 准教授 久徳 浩太郎 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DFAM