"Eating alone is painful" : an interdisciplinary and ethnographically inspired sociolinguistic investigation into Vietnamese mealtime ritual invitations : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Linguistics at Massey University, Auckland, New Zealand

Invitations are a commonplace part of language ritual at meals in Vietnamese culture. They are verbal and non-verbal signals extended around everyday meals and interpreted as offers or invitations for food and/or company at meals. These invitations form communal and familial bonds and serve as a means to maintain hierarchical order. However, the commonly-held misperceptions of these invitations include them being explicitly verbalised, occurring only at meal-starts, and being specific to regions and people groups. Previous studies discussed the language of invitations from a narrow linguistic perspective which led to limited understandings of their nature and of how contextual and social factors govern their usage. My research examines linguistic and cultural perceptions and usage of Vietnamese mealtime ritual invitations (VMRIs) by about 350 native speakers of Vietnamese in New Zealand and Vietnam. My study draws on 18 months of ethnographic fieldwork data, including participant observations, informal talks, diaries, video-recordings, and interviews. This is an interdisciplinary study drawing upon theoretical ideas from Sociolinguistics and Cultural Anthropology to analyse and interpret the data. The main findings are from two perspectives. From a linguistic perspective, VMRIs exhibit several features. Firstly, their linguistic variants are diverse. Secondly, particular linguistic features can express formality, politeness, hierarchical respect, and communicative conventions. Thirdly, key sociocultural variables (age, gender, familiarity, perception, and socio-family status) appear to influence usage. From an anthropological perspective, VMRIs are daily-life ritual practices manifesting the value of food in Vietnamese socio-cultural and historical context of food insecurity, the significance of family meals and meal manners, and the role of women. This study on Vietnamese mealtime ritual invitations expands the conceptual boundaries of invitations as multiplex discourses by showing how context (food and family meals) and other factors (status, familiarity, age, gender, and perception) generate and constrain language use. It also highlights the interrelationship between language and behaviour, the ritual practice of familial bonding during mealtimes, and the role of women in Vietnamese society. The findings emphasise the importance not only of taking account of speakers and hearers’ identities and discursive contexts when interpreting contextual language use but also of identifying those contexts

Estimation of the Hurst and the stability indices of a HH-self-similar stable process

In this paper we estimate both the Hurst and the stable indices of a H-self-similar stable process. More precisely, let $X$ be a $H$-sssi (self-similar stationary increments) symmetric $\alpha$-stable process. The process $X$ is observed at points $\frac{k}{n}$, $k=0,\ldots,n$. Our estimate is based on $\beta$-variations with $-\frac{1}{2}<\beta<0$. We obtain consistent estimators, with rate of convergence, for several classical $H$-sssi $\alpha$-stable processes (fractional Brownian motion, well-balanced linear fractional stable motion, Takenaka's processes, L\'evy motion). Moreover, we obtain asymptotic normality of our estimators for fractional Brownian motion and L\'evy motion. Keywords: H-sssi processes; stable processes; self-similarity parameter estimator; stability parameter estimator

Chemical probes of surface layer biogenesis in Clostridium difficile

The bacterium Clostridium difficile is responsible for recent epidemics of gastroenteritis and currently causes over twice as many deaths per year as the other major hospital ‘superbug’, MRSA. Since the bacterium is resistant to conventional antibiotics there is an urgent need to develop novel therapies. C. difficile secretes a family of proteins that are held in place on the cell wall by non-covalent forces, producing a proteinaceous coat (the surface layer or S-layer) that surrounds the entire cell. These S-layer proteins (SLPs) are immunogenic in humans and play a role in binding to host cells. Synthesis of the C. difficile S-layer involves site-specific proteolytic cleavage of the SlpA precursor by an as yet unidentified C. difficile protease. Identification of the protease that processes SlpA has proven challenging, due in part to a lack of established genetic tools in C. difficle. Here the development of novel chemical probes that can disrupt S-layer formation by inhibiting the protease are described, and found to be powerful chemical proteomic tools for both protease identification and exploring the process of S-layer formation. Screening and inhibition experiments were first performed to identify novel synthetic irreversible protease inhibitors combining an electrophilic warhead with a specific sequence element matching the SlpA cleavage. These compound series were shown to possess structure-dependent activity, and inhibited cultures were also more sensitive to lysozyme-induced cell lysis, suggesting that correct processing and assembly of the S-layer is important for cell envelope integrity. Optimised inhibitors were further developed into ‘activity-based probes’ (ABPs) carrying an affinity tag, and were successfully used to isolate and identify de novo the key protease involved in cleavage of SlpA, Cwp84, using a combination of different labelling and proteomics approaches. These probes also permitted identification of Cwp84 activity across a wide range of clinical strains. In later work, the scope of the warhead element was explored in more detail, and the potential antibacterial effects of the inhibitors were investigated in both wild type and genetically engineered strains. Finally, the contributions of this work in terms of both chemical technology and C. difficile biology are critically assessed