<p>This paper analyses the pricing on spare parts. Empirical studies have showed that manufacturers of durable goods make an unproportional large profit on its spare parts in relation to the revenue it generates. It is first showed that according to the standard economic model the price on spare part ought to be zero since the producer include an insurance in the price of the main good. Further it is showed that moral hazard alone do not explain the pricing found in the studies. Finally an analysis of whether consumers with present-biased preferences could be a possible explanation is made. The analysis finds that it is a possibility however somewhat unlikely.</p>

Thesis (Ph. D.)--University of Texas at Austin, 2006. / Vita. Includes bibliographical references.

This paper analyses the pricing on spare parts. Empirical studies have showed that manufacturers of durable goods make an unproportional large profit on its spare parts in relation to the revenue it generates. It is first showed that according to the standard economic model the price on spare part ought to be zero since the producer include an insurance in the price of the main good. Further it is showed that moral hazard alone do not explain the pricing found in the studies. Finally an analysis of whether consumers with present-biased preferences could be a possible explanation is made. The analysis finds that it is a possibility however somewhat unlikely.

A la hora de comprar a crédito, la evidencia empírica así como la meramente anecdótica sugieren que los consumidores se centras más en la cuantía de los pagos mensuales que en el tipo de interés del préstamo o la cantidad total que han de pagar. Los dos primeros capítulos de esta tesis exploran el papel del los problemas de auto control a la hora de explicar este comportamiento. Nuestro análisis se basa en el supuesto de descuento hiperbólico (Laibson (1997)) como forma de modelar el auto control. En el primer capitulo de la tesis consideramos un modelo de equilibrio parcial en el que la duración del préstamo y el tipo de interés están fijos y los consumidores pueden elegir cuánto tomar prestado y como repartir la devolución del préstamo entre los diferentes periodos. Mostramos que tener problemas de auto control implica mayores niveles de endeudamiento y que ser consciente de estos problemas o poseer la capacidad de comprometerse a un curso de acción reduce la presión sobre esos niveles. También demostramos que tener problemas de auto control y ser naif sobre ellos puede inducir una preferencia por los préstamos que requieren mayores cuotas hacia el final de su duración. El segundo capitulo analiza la interacción entre un prestamista monopolístico y un consumidor con descuento cuasi hiperbólico en un modelo en el que asumimos cuotas mensuales idénticas y permitimos al consumidor elegir entre distintas duraciones del préstamo. Obtenemos que mientras el tipo de interés del préstamo permanezca por encima del tipo de interés de mercado, en un contrato de equilibrio los consumidores con preferencias dinámicamente inconsistentes eligen préstamos con mayor duración (y por lo tanto con cuotas mensuales más bajas)El tercer capitulo de esta tesis, un trabajo conjunto con Alena Bicakova, proporciona evidencia empírica sobre el impacto de los problemas de auto control en el comportamiento de los consumidores a la hora de pagar sus deudas. El análisis viene motivado por resultados de encuestas que indican que un porcentaje significativo de los prestatarios atribuyen a una mala gestión de la deuda sus dificultades financieras. Esto contrasta con el argumento económico estándar según el cual la falta de pago de una deuda se debe a shocks negativos inesperados ya sea en los ingresos o en los gastos. Nuestra conjetura es que la mala gestión de la deuda y la falta de autocontrol están relacionadas y que tienen efectos adversos sobre el comportamiento de los prestatarios a la hora de devolver su deuda. Con el fin de verificar esta conjetura utilizamos una base de datos única en su naturaleza y procedente de una organización benéfica dedicada a la orientación a consumidores con créditos del Reino Unido. La orientación de crédito asiste a prestatarios seriamente endeudados mediante la elaboración y administración de unos planes de repago llamados Planes de Gestión de Deuda (DMP en ingles). Mostramos que la probabilidad de abandonar un DMP aumenta en un 12% y en un 31% respectivamente cuando las razones que se aducen para explicar el exceso de deuda (relacionadas con su mala gestión) y fumar se utilizan como indicadores. Como hasta cierto punto estos indicadores pueden usarse como una medida aproximada de los problemas de auto control, nuestros resultados sugieren una potencial relación entre las tasas de morosidad y la falta de auto control. / When buying on credit, anecdotal and empirical evidence suggest that the consumers focus more on the size of the monthly payments than on the interest charged on the loan or the total amount they pay. The first two chapters of this thesis aim to explore the role of self-control problems in explaining this puzzling behaviour. Our analysis relies on the assumption of the "quasi-hyperbolic discounting" (Laibson (1997)) to model self-control. In the first chapter of the thesis, we consider a partial equilibrium setting in which the loan maturity and the interest rates are fixed and the consumers can choose how much to borrow and how to allocate the repayments between different periods. We show that having self-control problems implies higher levels of borrowing whilst awareness of self-control problems or a lack of commitment puts downward pressure on that level. We also demonstrate that having self-control problems and being naive about them can induce a preference for back-loaded repayment plans which require higher repayments towards the end of the loan term. The second chapter looks at the interaction between a monopolistic lender and a consumer with quasi-hyperbolic discounting in a setting where we assume equal monthly payments and allow the consumer to choose between different loan maturities. We show that when market risk free rate exceeds the long run discount rate, in an equilibrium contract, the consumers with dynamically inconsistent preferences choose the loan with longer maturity (hence lower monthly payments). Third chapter of this thesis, which is a joint work with Alena Bicakova, provides empirical evidence on the impact of self-control problems on consumers' debt repayment behaviour. The analysis is motivated by the survey evidence which shows that a significant percentage of borrowers blame the debt mismanagement as the reason for running into financial troubles. This contrasts with the standard economic argument that default on debt is caused by the unexpected negative shocks to income or to expenditure. Our conjecture is that the debt mismanagement and lack of self-control are linked, and they have adverse effects on the debt repayment performance of the borrowers. In order to test this conjecture, we use a unique administrative data set of a major consumer credit counselling charity in the UK. Credit counselling assists heavily indebted borrowers by setting up and administering repayment plans, so called debt management plans or DMPs. We show that probability of dropping out from a DMP increases by 12 per cent and 31 cent when the self-reported reasons for becoming overindebted (related to debt mismanagement) and smoking are used as indicators, respectively. To the extent that these indicators can be used as a valid proxy for self-control problems, our results point to a potential link between default rates and lack of self-control.

Accelerator architectures are used to accelerate the simulation of nonlinear hyperbolic PDEs. Three different architectures, a multicore CPU using threading, IBM’s Cell Processor, and Nvidia’s Tesla GPUs are investigated. Speed-ups of between 40-75× relative to a single CPU core in single precision are obtained using the Cell processor and the GPU. The three implementations are extended to parallel computing clusters by making use of the Message Passing Interface (MPI). The resulting hybrid-parallel code is investigated for performance and scalability on both a GPU and Cell computing cluster.

Accelerator architectures are used to accelerate the simulation of nonlinear hyperbolic PDEs. Three different architectures, a multicore CPU using threading, IBM’s Cell Processor, and Nvidia’s Tesla GPUs are investigated. Speed-ups of between 40-75× relative to a single CPU core in single precision are obtained using the Cell processor and the GPU. The three implementations are extended to parallel computing clusters by making use of the Message Passing Interface (MPI). The resulting hybrid-parallel code is investigated for performance and scalability on both a GPU and Cell computing cluster.

The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Title from PDF of title page (University of Missouri--Columbia, viewed on January 14, 2010). Thesis advisor: Dr. Alex Iosevich. Includes bibliographical references.

This dissertation provides the first known examples of finite co-volume Kleinian groups which have co- final towers of finite index subgroups with positive rank gradient. We prove that if the fundamental group of an orientable finite volume hyperbolic 3-manifold has fi nite index in the reflection group of a right-angled ideal polyhedron in H^3 then it has a co-fi nal tower of fi nite sheeted covers with positive rank gradient. The manifolds we provide are also known to have co- final towers of covers with zero rank gradient. We also prove that the reflection groups of compact right-angled hyperbolic polyhedra satisfying mild conditions have co-fi nal towers of fi nite sheeted covers with positive rank gradient. / text

We construct Fuchsian groups [Gamma] of signature (0 : 2, ... ,2 ;1;0) so that the set of hyperbolic fixed points of [Gamma] will contain a given finite collection of elements in the boundary of the hyperbolic plane. We use this to establish that there are infinitely many non-commensurable non-cocompact Fuchsian groups [Delta] of finite covolume sitting in PSL₂(Q) so that the set of hyperbolic fixed points of [Delta] will contain a given finite collection of rational boundary points of the hyperbolic plane. We also give a parameterization of Fuchsian groups of signature (0:2,2,2;1;0) and investigate when particular hyperbolic elements have rational fixed points. Moreover, we include a detailed list of the group elements and their killer intervals for the known pseudomodular groups that Long and Reid found; in addition, the list contains a new list of killer intervals for a pseudomodular group not found by Long and Reid. / text

This report discusses two examples of the use of Poincare disc models and their different relationships to Euclidean geometry. The topics include light reflection in hyperbolic geometry and the Hyperbolic Pythagorean Theorem; all in relation to the Poincare unit disc and Poincare upper half plane model. / text