http://hdl.handle.net/11343/159 Thu, 22 Jun 2017 21:30:38 GMT 2017-06-22T21:30:38Z http://hdl.handle.net/11343/177358 Optimal market thickness and market design Muir, Ellen Victoria In this thesis we primarily focus on developing tractable dynamic market models, together with applications of these models. We also address several open questions concerning the statistical properties of static market models. The original research contained in this thesis begins when we define a new distribution, called a general non-central hypergeometric distribution, which models biased sampling without replacement. We then consider a classic mechanism design market model with unit traders in which buyer valuations and seller costs are independent and, on each side of the market, identically distributed. We show that the equilibrium quantity traded has a general non-central hypergeometric distribution under a broad class of mechanisms, where the sampling bias encodes information about the distribution of buyer values relative to seller costs, strategic behaviour of market participants and rent extraction by the market intermediary. We then extend this work by developing a general approach to approximating outcomes in large markets. In particular, we show that the joint distribution of the equilibrium quantity traded and welfare is asymptotically normal, compute the parameters of the approximating normal distribution and bound the approximation rate. We then turn our attention to dynamic market models in which traders with persistent types arrive over time and focus on optimally assessing the tradeoff between the benefits of increasing market thickness and the cost of delay. We start by considering a two-period extension of the classic model of Myerson and Satterthwaite and derive the class of Bayesian optimal mechanisms. Investigating the properties of these mechanisms, we compare them to benchmark static mechanisms and find that dynamics tends to increase the convexity of the region of trade in period one. Motivated by the computational complexity of these optimal mechanisms, we consider approximate implementation in the form of a price-posting mechanism, before turning our attention to models with simpler type spaces. Finally, we consider an infinite-horizon market model in which agents have binary type spaces. Assuming that a buyer-seller pair arrives in each period and agents are privately informed about their types, we introduce notions of dynamic efficiency and optimality and construct the class of Bayesian optimal mechanisms. We demonstrate that, provided the discount factor is sufficiently large, a profit-maximising two-sided platform creates higher welfare compared to a less centralised, welfare-targeting market maker. Further, the main benefits from dynamic mechanisms are reaped by clearing markets at fixed, optimally chosen frequencies. We consider a variety of economic applications including in-house production by the designer, taxation policy and asymptotically optimal prior-free mechanisms. With minor qualifications (including a dynamic generalisation of Myerson regularity), our analysis and main results apply to more general arrival processes and type spaces. © 2017 Dr. Ellen Victoria Muir Sun, 01 Jan 2017 00:00:00 GMT http://hdl.handle.net/11343/177358 2017-01-01T00:00:00Z http://hdl.handle.net/11343/177357 How cinema surrounds us: the psychology of psychogeography in the works of Sofia Coppola Henderson, Laura Clare Mereki The settings and spaces presented to the spectator by a film can be some of the most memorable and pleasurable elements of cinema. While the affective turn in screen theory has moved towards a consideration of an embodied spectator, there is still little consideration of how the spectator experiences filmic space. Moreover, although there is significant evidence that many elements of this interaction occur at a neurological level, few scholars have taken this into consideration. This dissertation aims to address these gaps by engaging contemporary film theory with recent areas of psychological research. By juxtaposing these two bodies of knowledge in an analogic flow, new ways of understanding how the spectator interacts with a cinematic world emerge. Taking the work of Sofia Coppola as a case study, the thesis builds on Giuliana Bruno’s account of the psychogeography of cinema, and demonstrates that the perception of filmic landscapes is a neurally embodied, intimate and intersubjective practice. The major findings presented concern the ways the perception of cinematic psychogeographies mirror, incite and operate upon the neural underpinnings of consciousness. The research also interrogates how a spectator constructs personal relationships with film spaces, how these spaces change our perception of the material world, and how this might impact on the study of film spectatorship. The personal construction of film spaces indicates a direct and neurally intimate relationship between text and spectator. This thesis tenders a possible (and currently unexplored) avenue for the study of spectatorship that reflects this relationship. © 2017 Dr. Laura Clare Mereki Henderson Sun, 01 Jan 2017 00:00:00 GMT http://hdl.handle.net/11343/177357 2017-01-01T00:00:00Z http://hdl.handle.net/11343/177356 The genomic basis of climate and host adaptation Rane, Rahul Vivek Many species are currently threatened by the direct and indirect effects of anthropogenically driven climate change. The elevation of global temperatures and increase in variability in both temperature and precipitation pose a risk to biodiversity as species are pushed close to their thermal safety margins. Current predictions suggest a dramatic loss of species diversity and the contraction of geographical ranges of many species. Many ectothermic insects that cannot regulate their body temperature are likely to be threatened, particularly ecologically- restricted herbivorous insects that depend for on plants for food and that are often in phenological synchrony with their plant hosts. However, adaptive shifts in these species in response to host loss and climatic extremes may counter the effects of climate change to some extent. This highlights the importance of studying species-specific adaptation mechanisms including host interactions. This dissertation contributes to this overall aim by studying the genomic basis of climatic and host adaptation. I use Drosophila melanogaster as a model system at the intraspecific level, and Drosophila species from the repleta group as a model system for the comparative level. In assessing the genomic basis of host responses, I consider a much broader range of insect taxa. This dissertation begins with a study on the use of chromosome level sequencing of D. melanogaster populations from two ends of a thermal cline. I present genomic evidence for the role of the inversion 3R Payne in capturing alleles favourable to local climatic conditions in the non-inverted form, and therefore driving adaptation to climate change. The study further elucidates the impact of climatically important chromosomal inversions in driving higher linkage disequilibrium on the non-inverted form - potentially benefiting both karyotypes. In the second chapter, I develop a new pipeline, Orthonome, and tools for multi-species comparisons for prediction of orthologues and inparalogues with the highest accuracy and recall. Using Orthonome, I was able to identify a much greater level of conservation across Drosophilid lineages than earlier thought, amounting to nearly 33% better resolution than industry-accepted methods. I then use Orthonome in the third chapter to compare the genomes of 58 insect species – most of which are known to be agricultural pests. Testing across eight gene families, I present evidence for genomic patterns in only four gene families (P450s, CCEs, GSTs and ABCs) as being associated with polyphagy or particular host ranges. While three of them have been reported before, I find that ABC transporters present much stronger evidence than reflected in earlier studies, with feeding behaviour as well as host tissue displaying an effect on gene gain in more voracious pest species. Finally, in the last study, I use novel genomic data and evidence from the repleta group of drosophilids to carry out phylogenetically constrained analyses of genes potentially associated with host and thermal stress adaptation. My aim here is to find mutually exclusive evolutionary pathways to neofunctionalisation between stress tolerant cactophilic specialists and less tolerant generalists in the group. I also find a different adaptive response in the cactophilic species compared to the generalist species; these species show little lineage specific gene gain, suggesting an exception to current standing theories on neofunctionalisation for adaptation. I further discuss the applicability the species level and order level analyses for an overall detailed and systematic approach to identify the genomic basis of climatic and host adaptation. © 2017 Dr. Rahul Vivek Rane Sun, 01 Jan 2017 00:00:00 GMT http://hdl.handle.net/11343/177356 2017-01-01T00:00:00Z http://hdl.handle.net/11343/176339 Unfolding/Folding JUST, KATHLEEN Fri, 01 Jan 2016 00:00:00 GMT http://hdl.handle.net/11343/176339 2016-01-01T00:00:00Z