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Complex-phase (CP) steels are employed in applications that require high-strength and good edge formability. These steels derive their strength from a fine-grained bainite-ferrite microstructure, and alloying to provide solid-solution and precipitation strengthening. CP steels are produced industrially through a process of controlled rolling and cooling to produce desirable microstructures. Hole-expansion tests are typically used as a measure of edge formability for applications such as stretch-flanges. It has been shown that CP microstructures are susceptible to large fluctuations in hole-expansion performance with little change in processing or resulting tensile properties. The steel’s characteristics of damage evolution are critical to the hole-expansion performance. This study investigates the role of microstructure in the development of damage in CP microstructural variants. Two variant pairs of different thicknesses were produced from the leading and trailing edge of industrially produced hot-rolled sheet. Each pair consisted of a variant with poor hole-expansion performance, and a variant with good hole-expansion performance. Each variant was tested via interrupted double-notched uniaxial tension testing to induce damage. Damage evolution in each variant was quantified by X-ray micro-computed tomography (XµCT), and supplementary optical micrography. The damage results were correlated with microstructural characteristics. It was shown that poor hole-expansion variants failed by intergranular fracture. In these variants, void damage induced by hard martensite and retained austenite was not critical in producing failure. Purely void-damaged microstructures failed by ductile fracture, whereas cracked microstructures failed in a mixed brittle-ductile failure initiated by planar cracks. Microstructural banding of large elongated ferrite grains correlated with the existence of intergranular planar fractures. / Thesis (Master, Mechanical and Materials Engineering) -- Queen's University, 2013-12-17 15:03:02.206

The study of DNA variation is one of the most promising avenues for learning about the evolutionary and historical past of humans and other species. However, the difficulty associated with obtaining DNA directly from ancient remains have for long kept genomic studies of population history trapped in time; confined to interpreting patterns of modern-day variation without direct historical observations. In this thesis, I outline new approaches for the retrieval, analysis and interpretation of large-scale genomic data from ancient populations, including solutions to overcome problems associated with limited genome coverage, modern-day contamination, temporal differences between samples, and post-mortem DNA damage. I integrate large-scale genomic data sets from ancient remains with modern-day variation to trace the human past; from traits targeted by natural selection in the early ancestors of anatomically modern humans, to their descendants' interbreeding with archaic populations in Eurasia and the spread of agriculture in Europe and Africa. By first reconstructing the earliest population diversification events of early modern humans using a novel large-scale genomic data set from Khoe-San populations in southern Africa, I devise a new approach to search for genomic patterns of selective sweeps in ancestral populations and report evidence for skeletal development as a major target of selection during the emergence of early modern humans. Comparing publicly available genomes from archaic humans, I further find that the distribution of archaic human ancestry in Eurasia is more complex than previously thought. In the first direct genomic study of population structure in prehistoric populations, I demonstrate that individuals associated with farming- and hunter-gatherer complexes in Neolithic Scandinavia were strongly genetically differentiated, and direct comparisons with modern-day populations as well as other prehistoric individuals from Southern Europe suggest that this structure originated from Northward expansion of Neolithic farming populations. Finally, I develop a bioinformatic approach for removing modern-day contamination from large-scale ancient DNA sequencing data, and use this method to reconstruct the complete mitochondrial genome sequence of a Siberian Neandertal that is affected by substantial modern-day contamination.

The water vole is common in Middle and Late Pleistocene temperate Palaearctic faunas. It is widely used in biostratigraphy because of tem- poral trends in the size, shape and structure of the first lower molar (M1). However, geographic variation in the evolutionary development of the M1 has restricted the precision and accuracy of age-estimations. This thesis explores morphological variation in the M1 of fossil and extant populations of the lineage Mimomys savini–Arvicola, and uses the phenotype and the genotype to develop evolutionary hypotheses. Geometric and traditional morphometric methods are used to quantify tooth shape and enamel thickness from over 4000 digital photographs of M1s taken from specimens originating from 146 modern and fossil groups across the western Palaearctic. M1s are photographed to ob- tain a true cross-section, giving a more accurate description of molar shape. Morphological variation is explored in terms of sample-size, taphonomy, and ontogeny. Sample sizes of less than 10 are likely to provide inaccurate summary statistics of morphometric variables but depositional type appears to have no systematic effect on within-group variation. Change in the morphology of M1s through ontogeny is an im- portant source of morphological variation, explaining up to 29% of mo- lar shape within-specimens and up to 95% of enamel thickness within enamel layers of specimens. Removal of ontogenetic variation from mo- lar shape improves congruence between morphological and molecular data, indicating age-corrected variables should be used when assessing evolutionary patterns. Temporal and spatial patterns in the enamel thickness quotient (SDQ), based on age-corrected enamel thicknesses, mirror those from published data but differ in some details. Method- ological differences mean absolute SDQ values cannot be compared. Qualitative patterns include a large decrease in SDQ across MIS 12 and a steep east–west morphocline during the late Middle Pleistocene.

This thesis examines the evolutionary biology of the RNA viruses, a diverse group of pathogens that cause significant diseases. The focus of this work is the relationship between the processes driving the evolution of virus populations within individual hosts and at the epidemic level. First, Chapter One reviews the basic biology of RNA viruses, the current state of knowledge in relevant topics of evolutionary virology, and the principles that underlie the most commonly used methods in this thesis. In Chapter Two, I develop and test a novel framework to estimate the significance of phylogeny-trait association in viral phylogenies. The method incorporates phylogenetic uncertainty through the use of posterior sets of trees (PST) produced in Bayesian MCMC analyses. In Chapter Three, I conduct a comprehensive analysis of the substitution rate of hepatitis C virus (HCV) in within- and between-host data sets using a relaxed molecular clock. I find that within-host substitution rates are more rapid than previously appreciated, that heterotachy is rife in within-host data sets, and that selection is likely to be a primary driver. In Chapter Four I apply the techniques developed in Chapter Two to successfully detect compartmentalization between peripheral blood and cervical tissues in a large data set of human immunodeficiency virus (HIV) patients. I propose that compartmentalization in the cervix is maintained by selection. I extend the framework developed in Chapter Two in Chapter Five and explore the Type II error of the statistics used. In Chapter Six I review the findings of this thesis and conclude with a general discussion of the relationship between within- and among-host evolution in viruses, and some of the limitations of current techniques.

Pragmatics is the branch of linguistics that addresses the relationship between language and its external environment – in particular the communicative context. Social evolution (or sociobiology) is the branch of the biological sciences that studies the social behaviour of organisms, particularly with respect to the ecological and evolutionary forces with which it must interact. These two disciplines thus share a natural epistemic link, one that is concerned with the relationship between behaviour and the environment. There has, however, historically been no dialogue between them. This thesis attempts to fill that void: it examines pragmatics from the perspective of social evolution theory. Chapter 1 gives a brief introduction to the two fields and their key ideas, and also discusses why an evolutionary understanding of pragmatics is crucial to the study of language origins. In chapter 2 the vexed question of the biological function of language is discussed. Responses are given to the claims, common in the evolutionary linguistics literature, that the processes of exaptation, self‑organisation and cultural transmission provide alternatives to natural selection as a source of design in nature. The intuitive conclusion that the function of language is communication is provisionally supported, subject to a proper definition of communication. Chapter 3 reviews previous definitions and consequently argues for an account predicated on the designedness of signals and responses. This definition is then used to argue that an evolutionarily coherent model of language should recognise the pragmatic realities of ostension and inference and reject the code‑like idealisation that is often used in its place. Chapter 4 observes that this fits the argument that the biological function of language is communication and then addresses the key question faced by all evolved communication systems – that of evolutionary stability. The human capacity to record and remember the past behaviour of others is seen to be critical. Chapter 5 uses the definition of communication from chapter 3 to describe a very general model of evolved communication, and then uses the constraints of that model to argue that Relevance Theory, or at least some theory of pragmatics with a very similar logical structure, must be correct. Chapter 6 then applies the theoretical apparatus constructed in chapters 2 to 5 to a crucial and topical issue in evolutionary linguistics: the emergence of learnt, symbolic communication. It introduces the Embodied Communication Game, an experimental tool whose basic structure is significantly informed by both social evolutionary and, in particular, pragmatic theory. The novelty of the game is that participants must find a way to communicate not just the content that they wish to convey, but also the very fact that a given behaviour is communicative in nature, and this constraint is found to fundamentally influence the type of system that emerges. Chapter 7, which concludes the thesis, recounts and clarifies what it tells us about the origins and evolution of language, and suggests a number of possible avenues for future research.