Doctor of Philosophy / Department of Psychological Sciences / Patrick A. Knight / A significant body of academic work has amassed supporting the importance of employee engagement in the workplace and its ability to influence business outcomes. However, much of this research has been concentrated in high-contact occupations in which the relationship between the employee and the customer is prolonged and involved (e.g., financial consulting, nursing, etc.). The current study utilized movie theatre environments to determine if the ability of employee engagement to influence service delivery and business outcomes persists in low-contact service environments. This research found that even in settings characterized by brief and perfunctory employee-customer interactions, employee engagement at the business unit level significantly influenced service delivery as measured by the resulting overall guest satisfaction. Furthermore, this relationship was fully mediated by guest satisfaction with friendliness of employees, speed of service and cleanliness of the environment which previous research has found to be the primary drivers of overall guest satisfaction within this environment. Partial support was found for the ability of employee engagement to significantly predict reductions in employee turnover as well as reductions in operational inefficiency and negligence. No support was found linking employee engagement to the productivity/profitability of the business unit. Given these research findings which provide additional support for the importance of having an engaged workforce, we examined how employee satisfaction with various aspects of the company and occupational environment correlate to the employee’s level of engagement. We further segment these correlations by demographic groups to better understand the relationships and more effectively target future initiatives geared toward the improvement of employee engagement.

M.Phil. (Optometry) / Please refer to full text to view abstract

Single Point Diamond Turning (SPDT) is a technology widely applied for the fabrication of contact lenses. One of the limiting factors in polymer machining is wear of the diamond tool due to electrostatic discharge resulting in poor surface quality of the machined products. The research work presented in this dissertation highlights the electrostatic properties of contact lenses during machining operations and the effects these properties have on the surface quality of the work piece materials. Two contact lens samples were experimented on, Definitive 74 (Silicone Hydrogel) and Tyro 97 (Rigid Gas Permeable). The electrostatic surface potentials (ESPs) were measured during turning operations using an electrostatic voltmeter and the surface roughness measurements were taken using a surface profilometer. Response Surface Methodology (RSM) techniques were employed to create predictive models for both surface roughness and ESPs with respect to the cutting speed, feed rate and depth of cut. Predictive surface roughness models were successfully generated for both materials and the cutting speed and feed rate were identified as the parameters with most effect on surface roughness. In addition, an electrostatic model was successfully generated for the Definitive 74 contact lens material which cited the cutting speed and feed rate as the most effective parameters on the material’s electrostatic behaviour. However, no relationship was evident between the machining parameters and electrostatic behaviour of Tyro 97.

This dissertation investigates the linguistic outcomes of Japanese-English language contact in Canada. Adopting a sociolinguistic variationist framework (Labov 1966; Sankoff & Labov 1985), the main objective is to determine whether or not Japanese spoken in Canada (hereafter, heritage Japanese) is showing structural change due to prolonged contact with English. The study is based on naturalistic speech data collected from 16 Japanese-English bilingual speakers in Canada. A key component of this dissertation is the use of a comparative sociolinguistic framework (Poplack and Tagliamonte 2001; Tagliamonte 2002) to assess structural affinities between heritage Japanese and the homeland Japanese benchmark variety. Speech patterns in heritage Japanese are systematically compared with patterns found in a commensurate monolingual benchmark variety of Japanese with regard to three linguistic variables, which are considered to be vulnerable to contact-induced language change (i.e. Bullock 2004, Sorace 2011). In terms of the first variable analyzed, variable realization of subject pronouns, it was found that the underlying grammar in heritage Japanese is shared by the homeland benchmark variety, showing that the variable is conditioned by the factor groups of subject continuity (i.e. switch reference) and grammatical person; the null variant is favoured by the same subject referent and the second person pronoun. Second, with regard to variable case marking on subject nouns and variable case marking on direct object nouns, it was found that the same underlying grammar is shared for case marking. For example, the constraint hierarchies in heritage Japanese were identical with those in the homeland variety for focus particles, with presence of a focus particle favouring null marking consistently for all types of nouns (i.e. English-origin nouns and Japanese nouns in heritage Japanese, and Japanese nouns and loanwords in homeland Japanese). The constraint hierarchies (and direction of the effect) for the other significant factor groups of verbal adjacency and sentence-final particle were identical between heritage Japanese and the homeland variety, with the exception of a reversed direction of effect for loanword subject nouns in heritage Japanese for the non-significant factor group of verbal adjacency, and a neutralized effect for Japanese nouns in heritage Japanese and loanwords in homeland Japanese when these nouns are located in direct object position. Considered in the aggregate, constraint hierarchies were found to exhibit a number of parallels across comparison varieties. This finding bolsters the general conclusion that there is little evidence indicating that extensive contact with English has had any discernible impact on structural patterns in these sectors of the heritage grammar. Furthermore, it was shown that no social factor group (i.e. length of stay in Canada) has an appreciable effect on heritage Japanese. Summarizing, the multiple lines of evidence emerging from the empirical quantitative analyses of the variables targeted in this dissertation converge in indicating that heritage Japanese, as spoken in Canada, broadly shares the same underlying grammar as homeland Japanese. Structural affinities in variable patterning shared by heritage and homeland varieties reveal little compelling evidence indicating that heritage Japanese exhibits structural change due to contact with English.

Les endommagements provoqués par le fretting sont multiples et peuvent causer de sévères disfonctionnements. Il est donc nécessaire d’étudier le fretting, en particulier dans le cas des alliages de titanes fréquemment employés dans l’aéronautique. Les endommagements générés par fretting peuvent être de l’usure, de la fissuration ou bien une combinaison des deux. La distinction entre ces deux comportements entraine régulièrement une dichotomie dans le choix des sujets traités. L’étude présentée ici fait le choix de rassembler en une seule démarche les études d’usure et de fissuration. Cette approche permet d’avoir une vision d’ensemble du comportement en fretting et fretting-fatigue d’un contact aube-disque dans un compresseur haute pression. Afin de respecter les contraintes industrielles, l’étude est réalisée à haute température (450°C) avec un contact plan sur plan revêtu. Pour réaliser cette étude, un dispositif expérimental original a été mis en place et validé. Les premiers résultats tribologiques montrent un effet majeur de la pression de contact sur le comportement tribologique de l’interface. Le coefficient de frottement du traitement de surface étudié diminue quand la pression de contact augmente. Une hypothèse d’expulsion du lubrifiant solide inclus dans le dépôt est proposée pour expliquer ce phénomène. Les résultats d’usure et notamment les analyses physicochimiques montrent un comportement sacrificiel du dépôt qui est usé préférentiellement au contre-corps. Cette caractéristique est bénéfique car dans l’application industrielle le contre-corps (le disque) doit être protégé en priorité par rapport à la pièce revêtue (l’aube). Les résultats d’usure dans la configuration industrielle sont complétés par une étude plus fondamentale mettant en évidence l’influence de la fréquence et du cycle de chargement du contact. La morphologie des traces d’usure est modifiée par ces deux facteurs, et le taux d’usure énergétique est également modifié. L’étude de la fissuration est menée en fretting simple et en fretting-fatigue. La fissuration du contre-corps non revêtu est modifiée par l’application d’un dépôt sur le poinçon revêtu. L’effet est principalement observable sur la longueur maximale de fissure, qui est divisée par deux dans le cas revêtu. Les résultats en fretting-fatigue sont également modifiés par la présence du revêtement, dont l’effet est plus présent pour les grands nombre de cycles. Enfin, une représentation des résultats sous forme de diagramme polaire normalisé est proposée afin de donner une image claire de l’ensemble des performances du dépôt. / Fretting damage is a major cause of defect. It is mandatory to study fretting in order to improve material performances, especially for titanium alloys used in aeronautics. Fretting induces wear, cracking or both damages in bodies in contact. The usual topics of fretting studies deal with one of these damages. In the one presented here, wear and cracking are studied simultaneously. This point of view allows a global approach of the blade-disk contact behavior in case of fretting in a turbojet high pressure compressor. Due to industrial constraints, the temperature of this study is 450°C and the contact geometry is coated plane on plane. This study is performed on an original experimental setup made for it. This setup enables fretting-fatigue tests at constant fretting force even if fatigue force varies. The first’s results regard tribological behavior. A significant effect of pressure is shown: the more the pressure, the smaller the coating friction coefficient. The given hypothesis is an expulsion of solid lubricant contained in surface treatment. Wear results show a sacrificial behavior of the coating. The surface treatment is worn preferentially than counter-body. From an industrial point of view, this characteristic is a good way to protect the uncoated counter-body (disk) instead of coated part (blade). In parallel, another study shows effect of frequency and load variation during cycle in a more fundamental case. Wear scar profile and wear rate is modified by these two parameters. Plain fretting tests and fretting-fatigue tests are performed to study fretting cracking process. Fretting induced cracking on counter-body is modified by coating on the punch. Maximal crack length is twice as short in coating condition as in uncoated condition. In fretting-fatigue, the coating is more efficient in high cycle fatigue. As a conclusion, a polar diagram is used in order to present global results and performances of the coating.

Les contraintes thermiques et mécaniques vues par les turbines haute pression ont conduit à la conception de turbines à aubes monocristallines. Ces aubes utilisent des nuances présentant d’excellentes propriétés en fluage selon les directions cristallographiques de type <001> et ont ainsi permis, en augmentant la température des gaz et la vitesse de rotation de la turbine, une amélioration des performances spécifiques des turbomachines. En utilisation, les aubes sont principalement soumises à l’accélération centrifuge induite par la rotation de la turbine autour de son axe. Ce chargement est cyclique avec des cycles qui correspondent au décollage/atterrissage, mais aussi à des vibrations aux fréquences plus hautes pendant la phase de vol. Le chargement de la pale est transmis au disque de turbine par une liaison de type pied de sapin, qui par nature contient un jeu. Au niveau du contact aube/disque les contraintes sont très élevées et des mouvements oscillatoires de faible amplitude apparaissent. Cette configuration de contact est appelée fretting et sa superposition avec la fatigue oligocyclique est appelée fretting fatigue. On rencontre le phénomène de fretting fatigue dans la plupart des contacts quasi-statiques subissant de la fatigue et des vibrations. C’est un phénomène qui réduit considérablement la durée de vie des assemblages. Les travaux de cette thèse se sont articulés autour de deux grands thèmes ; la connaissance du matériau et en particulier de la couche corticale (couche superficielle de la matière modifiée par le traitement de grenaillage) et l’étude des endommagements subits lors des différents chargements mécaniques élémentaire de l’attache aube/disque. Le grenaillage fait partie du processus de fabrication des pieds de pales. Il permet d’aplanir les rainures de rectification et de pré-contraindre localement le matériau en compression. Il a été montré par le passé qu’il augmentait la durée de vie moyenne en fatigue des éprouvettes technologiques représentatives de l’attache aube/disque. C’est donc un traitement mécanique fondamental. Sur un monocristal le grenaillage, en déformant plastiquement la couche corticale, modifie profondément la structure du matériau, et augmente significativement la concentration en dislocation. Ce nombre important de dislocations contribue à une rotation locale du réseau cristallographique. Ainsi la couche corticale ne peut plus être considérée comme orthotrope. Pour caractériser ces rotations, deux techniques ont été utilisées. Dans un premier temps, l’observation de la matrice γ a permis d’identifier la rotation du réseau cristallographique, ensuite une série de mesures par EBSD a permis de la quantifier. Par la suite, c’est la relaxation de la contrainte résiduelle introduite par le grenaillage dans un alliage polycristallin à base de nickel qui a été étudiée. Deux processus de relaxation ont été étudiés, le premier thermique et le second mécanique. Ces deux processus ont des cinétiques extrêmement importantes comparées à la durée de vie d’un moteur. Pour analyser le comportement en fissuration d’un plan monocristallin (MC2) soumis à une sollicitation de fretting imposée par un cylindre polycristallin (Udimet 720), trois orientations ont été sélectionnées parcourant l’ensemble des configurations rencontrées sur une aube. Les premiers résultats montrent que l’orientation du plan n’a pas d’influence sur le coefficient de frottement. Ensuite, le seuil d’amorçage a été déterminé, ce faisant les observations fractographiques des plans de MC2 ont mis en valeur l’importance de l’orientation relative des plans octaédriques et de la direction de fretting sur la direction de croissance des fissures. Ces constatations ont conduit à la réalisation de modèles éléments finis prenant en compte le caractère cubique des monocristaux de nickel et permettant d’évaluer l’amplitude du cisaillement résolu subi par un plan de fretting. [...] / No abstract

Allergic contact dermatitis is an important occupational health disease. It represents a useful experimental paradigm in which the mechanisms and characteristics of cutaneous immune responses can be investigated. This thesis has focused on the sensitization phase of contact allergy, including Langerhans’ cell (LC) migration, cytokine expression and the ability of the protein lactoferrin (LF) to modulate aspects of these processes. Lactoferrin was originally identified as an antimicrobial protein. However, it is being recognized increasingly to have immunomodulatory effects on the cells of the immune system. Migration of LC in mice and in humans is mediated via two independent cytokine signals delivered by tumour necrosis factor (TNF)-α and interleukin (IL)-1β, which were thought to derive from keratinocytes and LC, respectively. Further, topical application of LF was shown to inhibit LC migration in both man and mouse potentially through the inhibition of de novo TNF-α production. The inhibitory effect of LF on LC mobilization induced by the contact allergen 4-ethoxymethylene-2-phenyl-2-oxazolin-5-one (oxazolone) has been confirmed in these investigations. Conversely, LF did not inhibit LC migration triggered by another contact allergen, 2,4-dinitrochlorobenzene (DNCB). That result prompted a comparison between oxazolone and DNCB with respect to their ability to induce LC migration and to provoke cutaneous cytokine production. It was discovered that DNCB induced LC mobilization in the absence of TNF-α signalling. Moreover, exposure to superoptimal doses of oxazolone resulted in TNF-α independent LC migration. Further experiments revealed that TNF-α independence might be mediated partially by the elevated concentration of IL-1β produced in the skin following exposure to DNCB and these superoptimal concentrations of oxazolone. Investigations of the immunomodulatory mechanism of LF in vitro demonstrated that it did not inhibit TNF-α production by THP-1 macrophages. On the contrary, LF was shown to stimulate TNF-α and IL-8 release by THP-1 macrophages in a dose dependent manner, via endotoxin-independent and nucleolin-dependent mechanism. Subsequently, the role of LF in modulation of keratinocyte activation was investigated. Keratinocytes expressed high levels of inducible TNF-α mRNA, however, this was not modulated specifically by LF. Additional examination of the effects of LF in vivo revealed that it inhibited cutaneous IL-17 and CXCL1 mRNA expression, induced by IL-1β and IL-1α, respectively. Lactoferrin treatment did not affect oxazolone-induced lymph node (LN) cell proliferation. However, it was demonstrated to decrease IL-17 production by LN cells 24h following exposure to oxazolone, which may be important in driving the vigour and/or quality of response to the contact allergen. Overall, these investigations have demonstrated a divergence within the family of contact allergens with regard to the requirement for TNF-α signalling for LC mobilization. It was established that when elevated concentrations of IL-1β are present LC migration can occur in the absence of TNF-α signalling. Moreover, a dual nature of LF, which can act in a stimulatory as well as inhibitory manner, was confirmed. These investigations have revealed a potential role for CXCL1 and IL-17 in the process of LC migration. Furthermore, it was shown that the inhibitory effect of LF on oxazolone induced LC migration might be mediated via its effect on IL-17.

Code-switching is a language-contact phenomenon in which the juxtaposition of languages is intentional and purposeful. The Kuwaiti speech community has a distinctive code-switching mechanism because of the unique sociolinguistic and cultural setting; as they code-switch to English even though they are neither an immigrant community nor are/were colonised by an English speaking country. In Kuwait, code-switching between Kuwaiti Arabic and English is very common among the youth, even though English is considered to be a foreign language. It is observed that the code-switching behaviour of Kuwaiti bilinguals attending bilingual/multilingual schools differs from that of those attending monolingual schools. In this thesis, an ethnographic study has been conducted to corroborate this observation. Both bilingual/multilingual school students and bilingual students attending monolingual schools were interviewed in order to identify the motivations behind their code-switching behaviour. The interviews were analysed sequentially by adopting the conversational analysis framework. The sequential approach (Auer 1984) focuses on a turn-by-turn participant-oriented analysis (Li Wei 1994) to seek answers to the questions of how and why bilingual speakers code-switch. Here, the different code-switching behaviours of these young Kuwaitis were investigated in an attempt to analyse the conversational functions behind them. Without exception, bilinguals in monolingual schools preferred conversing in Kuwaiti Arabic with a few one-word English insertions here and there, even though free language choice was emphasised at the beginning of each conversation. On the other hand, the language choice of bilingual school students varied from choosing Kuwaiti Arabic or English as the language of conversation to code-switching between the two languages on a continuous basis. Code-switching ranged from English insertions into Kuwaiti Arabic speech or Kuwaiti Arabic insertions into English speech to alternating between the two languages. In addition to the different code-switching styles, various conversational functions behind code-switching were also recognised. In this thesis, code-switching was treated as a contextualisation cue (Gumperz 1982), highlighting the pragmatic functions and contributing to an understanding of the intended meaning. At least five motivations behind code-switching among bilingual school students were identified in our corpus: accommodation, repair, contrastiveness, filling linguistic gaps, and floor holding, among others.

The launch of silicone hydrogel contact lenses has led to a rise in the incidence of mechanically-related clinical complications, which is thought to be due to the increased stiffness of these materials compared to conventional hydrogel lens materials. The mechanical characteristics of hydrogel contact lenses have traditionally been investigated using tensile testing which investigated the bulk material characteristics. This thesis presents a study intended to establish a repeatable method for local mechanical measurement of hydrogel contact lenses using nanoindentation. Hydrogel materials in phosphate buffered saline were indented using a Hysitron Triboindenter mounted on a Veeco Explorer AFM using Triboscope software (version 3.5a) with a specially constructed wet cell. A model hydrogel (poly(HEMA-MMA)) was used to validate the methodology and investigate a the effect of controlled change in specimen thickness. A range of commercially available hydrogel contact lenses were then characterised (including conventional and silicone hydrogel lenses) using the same method. Two different analytical techniques were employed to determine the mechanical properties data; elastic analysis and a time-dependent viscoelastic analytical technique.A strong influence of specimen thickness on apparent mechanical properties was seen with the elastic analysis and an empirical relationship was derived to correct for this which was found to be appropriate for all contact lens specimens studied and reported in the thesis. The viscoelastic analysis results were more complex and exhibited a less clear influence of specimen thickness. However, as this is a very simple approximation as contact lenses are suspected to be poroelastic rather than viscoelastic this work could not be fully resolved in the scope of this thesis. For all contact lenses analysed, nanoindentation produced data similar to that found with conventional tensile testing, however, there was evidence for a slight dependence of elastic properties across the lens that does not correlate with sample thickness. This thesis shows the development of a way of accounting for the variation of thickness of a range of contact lenses, and demonstrated that traditional analysis is accurate enough to determine local differences in modulus across contact lenses. The viscoelastic analysis may be more appropriate for hydrogels, however, it produced irregularities that will require further work to fully resolve.

Les enjeux de consommation d'énergie et de sécurité ont fait du frottement entre les pneumatiques et la chaussée une propriété importante lors de la conception de nouveaux pneumatiques. Pour mesurer ces efforts de frottement deux cinématiques sont couramment utilisées : la mise en glissement et le roulement/glissement. Les lois de frottement issues des expériences de mise en glissement sont assez bien interprétées. En revanche, le lien qui existe entre ces lois de frottement et le comportement en roulement/glissement est encore mal compris. En particulier, les modèles de roulement/glissement n'incorporent pas la transition entre frottement statique et frottement dynamique, bien que cette phénoménologie soit bien établie expérimentalement. Dans cette thèse, nous proposons différents modèles de frottement en roulement/glissement qui étendent ceux de la littérature en intégrant explicitement la transition de frottement statique/dynamique. Pour tester ces modéles dans le cas du contact pneu/chaussée, nous avons réalisé des expériences selon les deux cinématiques, sur un contact simplifié élastomère/chaussée. A partir des expériences de mise en glissement, les paramètres de la loi de frottement sont identifiés, en fonction de la force normale appliquée, de la vitesse de glissement et de la nature de la chaussée. Ces résultats sont implémentés dans nos modèles, pour produire des prédictions en roulement/glissement, qui sont finalement comparées avec les mesures obtenues en roulement/glissement. De plus, certaines hypothèses des modèles ont été testées par des expériences de visualisation in situ du contact. En particulier nous confirmons, sur une interface élastomère/verre, la présence simultanée d'une zone collée et d'une zone en glissement en conditions de roulement/glissement. / For safety and energy consumption issues, tyre friction has become an important property when designing tyres. There are two main kinematic conditions which are commonly used to measure friction forces : the onset of sliding and the rolling/sliding. The friction laws which are extracted from the onset of sliding experiments are rather well interpreted. In contrast, the link between those frictions laws and the rolling/sliding behaviour remains incompletely understood. In particular, the rolling/sliding models do not take into account the transition between static friction and dynamic friction, although it is a well-established phenomenology. In this manuscript, we propose diérent models of friction in rolling/sliding, which extend those of the literature by explicitly integrating a static/dynamic friction transition. To test these models in the case of a tyre/road contact, we performed experiment in the two kinematic conditions, on a simpliéd elastomer/road contact. From the onset of sliding experiments, we identify the parameters of the friction law as functions of the applied normal force, the sliding speed and the type of road. These results are used as inputs in our models to predict the rolling/sliding behaviour, and are eventually compared with the corresponding experiments. In addition, we have tested several assumptions made in the models by performing in situ contact imaging experiments. In particular we con_rm, on an elastomer/glass interface, the simultaneous presence of a sticking and a slipping zone in rolling/sliding conditions.