In this thesis, we study the open book decompositions in high dimensional contact manifolds. We focus on the results about open book decomposition of manifolds and their relationship with contact geometry.

This thesis examines and compares the effectiveness of direct and indirect types of contact in leading to short- or longer-term prejudice-reducing outcomes in Cyprus. Chapter 1 provides a background to the relations between Greek and Turkish Cypriots and Chapter 2 provides a theoretical introduction to the intergroup contact hypothesis (Allport, 1954) and to extended friendships (Wright, Aron, McLaughlin-Volpe, & Ropp, 1997), vicarious contact (Mazziotta, Mummendey, & Wright, 2011), and imagined contact (Crisp & Turner, 2009) which have been suggested to be alternatives and a stepping stone to direct contact when the latter is absent. Chapter 3 consists of three experiments assessing the relative effects of direct and vicarious contact (Experiments 1 and 2) and imagined contact (Experiment 3). The results show that direct, and to a weaker extent, vicarious contact lead to more positive outgroup attitudes, but that a week after contact this effect is lost. All types of contact yield less anxiety, an effect that endures in time, and direct and imagined contact yield more positive action tendencies, an effect that remains significant in time only for direct contact. Chapter 4 consists of two experiments further exploring the capacity of imagined contact to yield positive intergroup outcomes. Experiment 4 tests whether the induction of interpersonal and intergroup similarities and/or differences into a positive imagined contact scenario affects participants evaluation of the outgroup. The results show, in line with the Optimal Distinctiveness Theory (Brewer, 1971), that ‘balanced similarity’ which incorporates both similarities and differences yields more positive outgroup attitudes than the conditions focusing only on similarities or only on differences. Experiment 5 compares ‘balanced similarity’ with positive imagined contact and finds that only the former affects variables related to preparing individuals for future contact. Chapter 5 consists of a three-wave longitudinal study examining the temporal effects of direct and extended friendships on outgroup attitudes and their mediation. Both types of friendships yield a significant indirect effect on attitudes which is stronger for direct friendships and is mediated by intergroup anxiety for both types of friendships and also by ingroup norms for direct friendships. Chapter 6 presents and discusses the key findings, outlines the limitations of these studies, and suggests avenues for future research.

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published_or_final_version / Mechanical Engineering / Doctoral / Doctor of Philosophy

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La recherche de batteries lithium-ion de hautes performances est nécessaire pour assurer nos besoins croissants en mobilité électrique. L’optimisation des matériaux d’électrodes et des électrolytes sont des voies très explorées. Par ailleurs, les collecteurs de courant jouent un rôle clé vis-à-vis des performances et de leur maintien au cours du cyclage en raison des problématiques d’adhésion, de résistance de contact électrique, et de corrosion, à l’interface électrode/collecteur. Dans ce but, des revêtements conducteurs et protecteurs pour collecteurs de courant en aluminium d’électrode positive ont été développés. Les phénomènes à l’interface entre l’électrode, de type LiFePO4 – PVdF, et le collecteur de courant ont été étudiés. Le mouillage de cette interface par l’électrolyte est apparu comme une origine majeure de la résistance de contact, probablement par la formation d’une double couche électrochimique. La sélection des matériaux utilisés dans la formulation des revêtements a permis de protéger la surface d’aluminium de ce contact avec l’électrolyte. Les conséquences sont très bénéfiques : diminution de la résistance de contact, augmentation des densités de puissance et d’énergie à hauts régimes, et protection de l’aluminium contre la corrosion dans un électrolyte de type LiTFSI. Il a notamment été montré qu’une des principales limitations d’une électrode de type LiFePO4 est sa résistance de contact avec le collecteur de courant, et qu’un revêtement performant permet d’éliminer totalement la part de carbone conducteur dans cette électrode tout en conservant de très bonnes performances. / Performance improvement is necessary in order to fulfill our increasing needs in electric mobility. Electrode and electrolyte materials optimization are privileged research directions. Furthermore, current collectors have a key role in the performance and their preservation, associated with electrode delamination, electrical contact resistance and corrosion issues at the current collector/electrode interface. To this end, conductive and protective coatings for aluminum current collectors have been developed. Interactions between a LiFePO4 – PVdF type electrode and current collectors were studied. The electrolyte wettability of this interface appeared to be a major contact resistance contribution, probably due to the formation of the electrochemical double layer. Protection of this interface was achieved through coatings’ material selection. Performance improvements have been observed: contact resistance decrease, higher power and energy densities at high rates and corrosion protection of aluminum substrates in LiTFSI-based electrolyte. It has been demonstrated that the contact resistance with current collectors is one of the major drawback of LiFePO4 electrodes, and an effective coating can allow the suppression of the electrode’s conductive carbon additives whereas performance are preserved.

The transition of neighbourhoods in post apartheid South Africa has not received adequate attention. Mondeor, a previously White populated suburb in the South of Johannesburg has been identified as progressively diverse in respect of racially diverse neighbourhoods in the aftermath of Apartheid. By focusing on this suburb, the current study investigated whether increased contact with members from different race groups in a residential neighbourhood promotes the formation of inter-racial friendships and social mixing. In addition, it explored whether there were particular associations which promoted interracial friendships or social mixing. Finally, the different types of contact occurring within the suburb were explored. In order to address the above questions the study followed a Qualitative Cross Sectional design. Data for the study was attained through in-depth interviews from twenty residents of Mondeor. The sample was further divided into five participants from each of the four major race groups prevalent in South Africa( African Black, White, and Indian and so-called Coloured). The results from this study found that racial proximity facilitated for much social mixing and a few friendship formations. Closer examination found that there was a reluctance to mix in the suburb however religious and educational institutions as well as recreational facilities in the neighbourhood promoted some integration in the area. In conclusion, the area was racially diverse however not significantly integrated.