Evolutionary approach to bilingualism

The ability to learn multiple languages simultaneously is a fundamental human linguistic capacity. Yet there has been little attempt to explain this in evolutionary terms. Perhaps one reason for this lack of attention is the idea that monolingualism is the default, most basic state and so needs to be explained before considering bilingualism. When thinking about bilingualism in this light, a paradox appears: Intuitively, learning two languages is harder than learning one, yet bilingualism is prevalent in the world. Previous explanations for linguistic diversity involve appeals to adaptation for group resistance to freeriders. However, the first statement of the paradox is a property of individuals, while the second part is a property of populations. This thesis shows that the properties of cultural transmission mean that the link between individual learning and population-level phenomena can be complex. A simple Bayesian model shows that just because learning one language is easier than two, it doesn't mean that monolingualism will be the most prevalent property of populations. Although this appears to resolve the paradox, by building models of bilingual language evolution the complexity of the problem is revealed. A bilingual is typically defined as an individual with "native-like control of two languages" (Bloomfield, 1933, p. 56), but how do we define a native speaker? How do we measure proficiency? How do we define a language? How can we draw boundaries between languages that are changing over large timescales and spoken by populations with dynamic structures? This thesis argues that there is no psychological reality to the concept of discrete, monolithic, static `languages' - they are epiphenomena that emerge from the way individuals use low-level linguistic features. Furthermore, dynamic social structures are what drives levels of bilingualism. This leads to a concrete definition of bilingualism: The amount of linguistic optionality that is conditioned on social variables. However, integrating continuous variation and dynamic social structures into existing top-down models is difficult because many make monolingual assumptions. Subsequently, introducing bilingualism into these models makes them qualitatively more complicated. The assumptions that are valid for studying the general processes of cultural transmission may not be suitable for asking questions about bilingualism. I present a bottom-up model that is specifically designed to address the bilingual paradox. In this model, individuals have a general learning mechanism that conditions linguistic variation on semantic variables and social variables such as the identity of the speaker. If speaker identity is an important conditioning factor, then `bilingualism' emerges. The mechanism required to learn one language in this model can also learn multiple languages. This suggests that the bilingual paradox derives from focussing on the wrong kind of question. Rather than having to explain the ability to learn multiple languages simultaneously as an adaptation, we should be asking how and why humans developed a flexible language learning mechanism. This argument coincides with a move in the field of bilingualism away from asking `how are monolinguals and bilinguals different?' to `how does the distribution of variation affect the way children learn?'. In this case, while studies of language evolution look at how learning biases affect linguistic variation, studies of bilingualism look at how linguistic variation affects learning biases. I suggest that the two fields have a lot to offer each other

Superparamagnetic Iron Oxide Nanoparticles: foundations for novel bioconjugate species and multimodal contrast agents

The properties of superparamagnetic iron oxide nanoparticles (SPION) have led to them being a major area of research within the ‘nano-revolution’. A number of SPION species have been used in disease imaging, including multimodal contrast agents active in positron emission tomography (PET) and magnetic resonance imaging (MRI), as well as bioconjugate species where biomolecules have been immobilised on the nanoparticle’s surface. The western world faces an epidemic of conditions for which monoclonal antibodies (mAbs)have become seen as a ‘magic bullet’. However, the expense of mAb therapy, possible side effects and the desire to maximise treatment success require improvements in patient stratification and selection. Chapter 1 introduces the field of biomedical imaging and immunotherapy and describes how research into immunoPET and PET/MRI imaging overlap in the following chapters. Chapter 2 describes the development of reliable, reproducible methods of synthesising SPION and introducing a number of biocompatible coatings with useful functionalities. These techniques underlie the chemistry to be discussed in Chapter 3- the immobilisation of biomolecules on the surface of SPION. Typical linker chemistry is discussed, with the relative merits of different approaches expanded upon. The effect of initial reaction stoichiometry on enzymatic activity is explored as a model for later experiment design. Chapter 4 incorporates several of the aspects examined in earlier chapters to describe the synthesis of radiolabelled SPION bioconjugated to the clinically approved antibody trastuzumab to give a novel immunoPET contrast agent. Fluorescence activated cell sorting (FACS) analysis and fluorescence microscopy confirm the in vitro validation of these agents. In vivo experiments show how these agents require further development before reaching a human clinical context. Chapter 5 relates the effort to synthesise novel coordination systems based on the hypoxiaselective imaging agent 64Cu-ATSM. The co-ordination chemistry of these systems with several metals is described

ColloCaid: A real-time tool to help academic writers with English collocations”

Writing is a cognitively challenging activity that can benefit from lexicographic support. Academic writing in English presents a particular challenge, given the extent of use of English for this purpose. The ColloCaid tool, currently under development, responds to this challenge. It is intended to assist academic English writers by providing collocation suggestions, as well as alerting writers to unconventional collocational choices as they write. The underlying collocational data are based on a carefully curated set of about 500 collocational bases (nouns, verbs, and adjectives) characteristic of academic English, and their collocates with illustrative examples. These data have been derived from state-of-the-art corpora of academic English and academic vocabulary lists. The manual curation by expert lexicographers and reliance on specifically Academic English textual resources are what distinguishes ColloCaid from existing collocational resources. A further characteristic of ColloCaid is its strong emphasis on usability. The tool draws on dictionary-user research, findings in information visualization, as well as usability testing specific to ColloCaid in order to find an optimal amount of collocation prompts, and the best way to present them to the user

Developing a writing assistant to help EAP writers with collocations in real time

Corpora have given rise to a wide range of lexicographic resources aimed at helping novice users of academic English with their writing. This includes academic vocabulary lists, a variety of textbooks, and even a bespoke academic English dictionary. However, writers may not be familiar with these resources or may not be sufficiently aware of the lexical shortcomings of their emerging texts to trigger the need to use such help in the first place. Moreover, writers who have to stop writing to look up a word can be distracted from getting their ideas down on paper. The ColloCaid project aims to address this problem by integrating information on collocation with text editors. In this paper, we share the research underpinning the initial development of ColloCaid by detailing the rationale of (1) the lexicographic database we are compiling to support novice EAP users’ collocation needs and (2) the preliminary visualisation decisions taken to present information on collocation to EAP users without disrupting their writing. We conclude the paper by outlining the next steps in the research