M.A. / Since the end of the Cold War era, peace and security have been the first priority of the African states. Africa has been afflicted by armed conflicts, wars and genocide since the African states gained their independence in 1960s. Presently, there are still some countries that are involved in conflicts including Sudan and Somalia. Armed conflicts undermine Africa's social and economic developments. Furthermore, this situation threatens African political stability in particular, peace and security. The international community is actively engaged in promoting peace, security and stability in Africa. So far, the United Nations (UN) has conducted eighteen peacekeeping operations and it still leads eight peacekeeping operations in Africa. It was found that peacekeeping operations are crucial to sustain peace and stability on the continent. The focus and aim of this study is to investigate cooperation between the European Union (EU) and the African Union (AU) with regard to peacemaking and peacekeeping in Africa. It was found that cooperation between the EU and AU has increased since the first EU-Africa Summit in Cairo in 2000. Both the EU and the AU have recently strengthened their relationship in a wide range of activities including human rights and governance, economic growth as well as peace and security. Importantly, the second EU-Africa Summit was held in Lisbon, in December 2007. At this, the EU highlighted the importance of a comprehensive, robust and long-term framework for its relations with the AU. The EU and Africa are connected by strong historical, trade and colonial links and the EU has a deep interest in a prosperous and stabilised Africa. Meanwhile, armed conflicts not only paralyse the African continent's, but also the European states' interests. Thus, the EU has reinforced its relationship with the AU in the fields of peace and security.

Les représentations de l’au-delà en Grèce ancienne, depuis Homère jusqu’auIVe siècle après J.-C., posent la question de l’élaboration d’un espace imaginaire etde la perception du temps dans une société. Le choix de privilégier des cadresd’étude limités mais suffisamment documentés permet d’établir des stratessuccessives de représentation de l’au-delà, toutes dominées par l’angoisse du passagedans l’autre monde. La comparaison des sources littéraires et des sourcesépigraphiques met en lumière les sentiments par rapport à l’au-delà et par rapport à lamort. Si le fatalisme domine largement à travers les époques, l’émergenceprogressive d’un jugement des défunts dans l’au-delà apporte l’espoir. Par ailleurs,les épitaphes permettent de distinguer ce qui relève des représentations collectives etdes représentations individuelles . Dans ces dernières, une large place est faite auxsentiments familiaux et à l’espoir de conserver une vie sociale dans l’au-delà. Lesreprésentations élaborées par des groupes religieux accentuent cet espoir qui est lamarque de l’initié. Le judaïsme hellénisé et le christianisme inscrivent cette attentede l’au-delà pour le fidèle dans une théologie de la rétribution.Les stéréotypes tenaces associés à l’au-delà, qui sont le plus souvent héritésde grands auteurs, de grands textes ou encore de l’iconographie attique se retrouventfortement nuancés. Le voyage dans la barque de Charon ou la présence de Cerbère nesont que des représentations d’une époque donnée. L’au-delà n’est donc pas unespace figé mais, bien au contraire, il évolue en fonction de circonstances sociales etculturelles / Representations of afterlife in ancient Greece, from Homer to the fourthcentury AD, raise the question of the elaboration of an imaginary space and timeperception in a society. The decision to focus on limited but well documentedspecific studies allows the identification of successive layers of representation ofafterlife, all dominated by the fear of crossing into the netherworld. The comparisonbetween the literary texts and epigraphic materials highlights the feelings concerningafterlife and death. If fatalism dominates throughout the ages, the gradual emergenceof a judgment of the deceased in the afterlife brings hope. Moreover, the epitaphsmake it possible to distinguish what belongs to the collective representations fromwhat belongs to the individual. In those ones, emphasis is given to family feelingsand the hope of maintaining a social life in the hereafter. Representations elaboratedby religious communities emphasize that very hope, which is the mark of the insider.Hellenized Judaism along with Christianism engrave this expectation of the afterlifefor the believers in a theology of retribution.Persistent stereotypes associated with afterlife - which are mostly inheritedfrom great authors, great texts or Attic iconography - are highly qualified. The trip inCharon’s boat, or the presence of Cerberus are only representations of a given era.Afterlife is not a fixed space but, quite the opposite, it evolves according to socialand cultural circumstances

Trace amounts of carbon monoxide, typically as low as 10 ppm CO, have a deleterious effect on the activation overpotential losses in proton exchange membrane (PEM) fuel cells. This is because CO preferentially adsorbs on the Pt electrocatalyst at the anode at typical PEM fuel cell operating temperatures, thereby preventing the absorption and ionisation of hydrogen. The inability of current preferential oxidation steps to completely remove CO from hydrogen-rich gas streams has stimulated research into CO tolerant anodes. As opposed to other CO oxidation catalysts, metal oxide supported gold catalysts have been shown to be active for the afore mentioned reaction at low temperatures, making it ideal for the 80°C operating temperatures of PEM fuel cells. The objective of this study was to investigate the viability of incorporating titanium dioxide supported gold (Au/TiO2) catalysts inside a PEM fuel cell system to remove CO to levels low enough to prevent poisoning of the Pt-containing anode. Two distinct methods were investigated. In the first method, the incorporation of the said Au/TiO2 catalyst inside the membrane electrode assembly (MEA) of a PEM fuel cell for the selective/preferential oxidation of carbon monoxide to carbon dioxide in hydrogen-rich gas fuels, facilitated by the injection of an air bleed stream, was investigated. It was important for this study to simulate typical fuel cell operating conditions in an external CO oxidation test rig. Factors such as gold loading, oxygen concentration, temperature, pressure, membrane electrode assembly constituents, water formation, and selectivity in hydrogen-rich gas streams, were investigated. The Au/TiO2 catalysts were prepared via deposition-precipitation, a preparation procedure proven to yield nano-sized gold particles, suggested in literature as being crucial for activity on the metal oxide support. The most active catalysts were incorporated into the MEA and its performance tested in a single cell PEM fuel cell. The catalysts proved to yield exceptional activity for all test conditions inside the CO oxidation test rig. However, no significant improvement in CO tolerance was observed when these catalysts were incorporated into the MEA. It was concluded that the thin bilayer configuration resulted in mass transfer and contact time limitations between the catalysts and the simulated reformate gas mixture. Other factors highlighted as possible causes of deactivation included the deleterious effect of the acidic environment in the fuel cell, the formation of liquid water on the catalyst’s surface, and the adverse effect of the organic MEA constituents during the MEA production procedure. The second method investigated was the incorporation of the Au/TiO2 catalyst in an isolated catalyst chamber in the hydrogen feed line to the fuel cell, between the CO contaminated hydrogen gas cylinder and the anode humidifier. Test work in a CO oxidation test rig indicated that with this configuration, the Au/TiO2 catalysts were able to remove CO from concentrations of 2000 ppm to less that 1.3 ppm at a space velocity (SV) of 850 000 ml.gcat -1.h-1 while introducing a 2 per cent air bleed stream. Incorporation of this Au/TiO2 preferential oxidation system into a Johnson Matthey single cell PEM fuel cell test station prevented any measurable CO poisoning when 100 and/or 1000 ppm CO, 2 per cent air in hydrogen was introduced to a 0.39 mg Pt.cm-2 Pt/C anode. These results were superior compared to other state of the art CO tolerance technologies. An economic viability study indicated that the former can be achieved at a cost of gold equal to 0.8 per cent of the USDoE target cost of $45/kW. This concept might allow fuel cells to operate on less pure hydrogen-rich gas, e.g. from H2 that would be stored in a fuel tank/cylinder but that would have some CO contamination and would essentially be dry. The use of less pure H2 should allow a cost incentive to the end user in that less pure H2 can be produced at a significantly lower cost.

Master of Science - Science / The theoretical investigation of the Optical Kerr Effect (OKE) and Third- Harmonic Generation (THG) of Au-VO2 nanocomposite thin-films undertaken in this project is motivated by the potential use of the Au-VO2 nanocomposite in nonlinear optical (NLO) devices. NLO devices are a driving force in today fs high technology industry. In this thesis the OKE is estimated and computed and will be compared later to the measured OKE using the Z-scan interferometric laser technique [47]. This is a simple yet highly sensitive single-beam experimental technique used to determine the real part of the dielectric susceptibility. The study of the OKE in these composites has shown that it has a high value, comparable to that found in Au-SiO2, Au-TiO2 and Au-Al2O3 thin-films [29, 33]. This is despite the fact that the Au volumetric concentration in the Au-VO2 composites considered here is 10 percent at most, whereas in the other above mentioned composite thin-films the volumetric concentration range was between 5 − 60 percent. Moreover, it has been demonstrated that the OKE is thermally tunable in the Au-VO2 thin-films, owing to the thermally tunable optical properties of the VO2 [8, 38]. It is found that the magnitude of the OKE is of the order of 10−6 esu when the composite is below 68 0C and it is of the order of 10−7 esu when the nanocomposite thin-film is above 68 0C. The large enhancement of the OKE is due to the surface plasmon resonance (SPR) of the nanogold particles. Its fast response, which is of the order of few picoseconds [4, 6, 7], makes the Au-VO2 nanocomposite a good candidate as a fast thermally tunable optical switch or modulator. The modelling here of high-order harmonic generation in strongly absorbing media, as regards the amplitude of the primary beam, takes into account pump attenuation only, due to the absorption of light by the media. It is not concerned with pump depletion which is a consequence of the transfer of energy to the harmonics and which is small by comparison with attenuation in absorbing media. The modelling is applied to the so-called transmission and reflection configurations. The former refers to the case in which the high-order harmonic wave is monitored in the same direction as the input fundamental wave, whereas the latter describes the situation in which the fundamental wave is in the opposite direction to the high-order harmonic one. To analyse high-order harmonic generation one has to relate the high-order harmonic intensity to the fundamental intensity [1, 9, 10, 34-36]. In so doing, a general formula for analysing high-order harmonic generation is obtained and reduced to the particular case pertaining to THG in strongly absorbing media. The ratio of the third-harmonic intensity to the fundamental intensity is termed the conversion coefficient or the conversion efficiency, and it is denoted by ƒÅ [23, 34]. It is useful in the sense that it expresses quantitatively the amount of input light of frequency ƒÖ converted into light of frequency nƒÖ, where n is the order of nonlinear polarisation [1]. It is found that the THG conversion coefficient is higher the higher the laser intensity. It is thus advantageous to use a pulsed laser, which achieved very high intensities for short periods, separated by long off periods. The net harmonic output in this case is much higher than one would obtain with a continous laser of the same average output. It is found here that ƒÅ is greater in the reflection configuration compared to the transmission one above and below Tt in the photon energy range 1.0 − 3.0 eV, see Fig. 5.1 to 5.8. However, the conversion efficiency for THG in the Au-VO2 nanocomposites for the picoseconds laser illumination we have considered, is still extremely low, and it is difficult to see a potential use for this system as a tunable frequency converter. The situation would become more favorable with the use of femtosecond laser pulses, where for the same pulse energy the intensity is much greater. The laser pulse energy must be limited to avoid excessive heating of the thin-film. The heat generated as a consequence of the illumination of the thin-film by the laser [23] may be controlled by using a simple cooling device which consists of a substrate on which the thin-film is deposited. The choice of such a substrate depends on whether THG is monitored in the transmission or reflection configuration. In the former a transparent substrate must be used (for example diamond) whereas in the latter an opaque substrate may be used (for example Ag). Calculations pertaining to the removal of heat from the illuminated film are reported, and show that thermal control is manageable but only within limits. To avoid a temperature rise of more than 5 0K the peak laser intensity we found must not exceed 7.4 ~105Wcm−2 with a pulse duration of 5 ps.

The growing fields of spintronics and nanotechnology have created increased interest in developing the means to manipulate the spin of electrons. One such method arises from the combination of the spin-orbit interaction and the broken inversion symmetry that arises at surfaces and interfaces, and has prompted many recent investigations on metallic surfaces. A method by which surface states, in the absence of spin orbit effects, have been successfully investigated is the Green function embedding scheme of Inglesfield. This has been integrated into a self consistent FLAPW density functional framework based on the scalar relativistic K¨olling Harmon equation. Since the spin of the electron is a direct effect of special relativity, calculations involving the spin orbit interaction are best performed using solutions of the Dirac equation. This work describes the extension of Green’s function embedding to include the Dirac equation and how fully relativistic FLAPW surface electronic structure calculations are implemented. The general procedure used in performing a surface calculation in the scalar relativistic case is closely followed. A bulk transfer matrix is defined and used to generate the complex band structure and an embedding potential. This embedding potential is then used to produce a self consistent surface potential, leading to a Green’s function from which surface state dispersions and splittings are calculated. The bulk embedding potential can also be employed in defining channel functions and these provide a natural framework in which to explore transport properties. A relativistic version of a well known expression for the ballistic conductance across a device is derived in this context. Differences between the relativistic and nonrelativistic methods are discussed in detail. To test the validity of the scheme, a fully relativistic calculation of the extensively studied spin orbit split L-gap surface state on Au(111) is performed, which agrees well with experiment and previous calculations. Contributions to the splitting from different angular momentum channels are also provided. The main advantages of the relativistic embedding method are the full inclusion of the spin orbit interaction to all orders, the true semi infinite nature of the technique, allowing the full complex bands of the bulk crystal to be represented and the fact that a only small number of surface layers is needed in comparison to other existing methods.

Les verres de phosphates à faible Tg et forte stabilité thermique sont étudié dans le système (66-x)ZnO- xNa2O-33.4 P2O5. Les mesures DSC ont montré un écart Tx-Tg de 197 °C et une Tg de 339 °C pour x= 20. La RMN 31P 1D/2D révèle la diminution du désordre due à la substitution progressive de Zn par Na. Les formulations x=20 et x=33 ont été dopé par de l’Al2O3, B2O3 et SiO2 (1-4 % mol.) et ses effets sur les propriétés physiques comme la température de transition vitreuse, la stabilité thermique et la durabilité chimique ont été investiguées. La DRX et la RMN 31P ont été réalisés pour suivre le processus de cristallisation en isotherme à 130°C (au-delà de la Tg). La plus forte stabilité thermique a été identifiée pour les verres dopés au bore. Le Raman et la RMN 31P ont mis en évidence l’existence de connections P-O-X (X=27Al ou 11B). La RMN a entre autre montré la coordinence majoritaire VI, IV et IV respectivement pour l’aluminium, le bore et la silice. L’utilisation de D-INEPT, REDOR et DQ-SQ permet d’approfondir nos connaissances sur la structure particulièrement sur les connectivités P-O-X mais également la diversité des connections possibles. / Pyrophosphate glass with low Tg and high stability is investigated within the (66-x) ZnO- xNa2O-33.4 P2O5 system. DSC measurement indicated Tx-Tg=197 °C with Tg = 339 °C at x= 20. 1D/2D 31P NMR revealed the decrease in extent of disorder with the progressive substitution of Zn by Na. The x=20 and x=33 formulations were doped with (1-4 mol.%) of Al2O3, B2O3 and SiO2 and its effect on the physical properties such as the glass transition temperature, thermal stability and chemical durability is investigated. XRD and 1D 31P solid state NMR were used to monitor the isothermal crystallization process occurring at 130 °C above Tg and the highest thermal stability is presented by the B-doped glasses. Raman and 31P NMR suggested the existence of P-O-X (X=27Al or 11B) bonds. The MAS NMR distinguished the dominant coordination states of doping elements AlVI , BIV and SiIV respectively. The use of D-INEPT, REDOR and DQ-SQ helped in producing deeper insights onto the glass structure about the P-O-X connectivity, the wide range of phosphate speciation.

Le confort est devenu un enjeu major dans le monde de travail. Parmi les diverses disciplines qui s’intéressent à ce concept, nous avons choisi d’articuler deux disciplines, l’architecture et la psychologie environnementale, pour mieux le cerner. Ainsi nous nous sommes appuyés sur les travaux de Vischer (2004) et Rioux (2013) en psychologie environnementale et ceux de « la démarche HQE » en architecture pour définir le confort par deux dimensions : physique et psycho-environnemental (évaluatif et psychologique). La dimension physique sera cernée par « la démarche HQE » et la dimension psycho-environnementale par la satisfaction environnementale au travail (confort évaluatif) et l’attachement au lieu de travail (confort psychologique). Notre travail de doctorat se propose de comparer le confort psycho-environnemental des soignants dans deux structures hospitalières tunisiennes se différenciant par leur architecture (pavillonnaire et monobloc) et de cerner l’impact des variables psycho-organisationnelles (épuisement professionnel, stress au travail et stratégies de coping) sur le confort psychologique dans ces deux hôpitaux. Une enquête par questionnaire a été menée auprès de 297 soignants travaillant dans les deux hôpitaux. Les résultats montrent notamment que les soignants de l’hôpital monobloc sont plus attachés mais moins satisfaits de leur environnement de travail que ceux de l’hôpital pavillonnaire ; ils se sentent plus épuisés et stressés et utilisent davantage de stratégies de coping centré sur l’émotion. L’impact des variables psycho-organisationnelles sur le confort psychologique des soignants diffèrent en fonction du type d’hôpital. / Comfort has become a major issue in the world of work. Among the various disciplines that have been interested in this concept, we have chosen to articulate two disciplines, notably architecture and environmental psychology. As such, this research relies on the work of Vischer (2004) and Rioux (2013) in environmental psychology and those of the « HQE Approach » in architecture in order to define comfort in terms of two dimensions: physical and psycho-environmental (evaluative and psychological). The physical dimension will be identified through the « HQE Approach » while the psycho-environmental dimension will be detected via the environmental satisfaction in the workplace (evaluative comfort) and via the attachment to the workplace (psychological comfort).Our research is meant to compare the psycho-environmental comfort of professional care providers in two different Tunisian hospital structures and whose difference lies in the architecture (pavilion and monobloc). The research attempts to detect the impact of psycho-organisational variables (professional burn out, perceived occupational stress and coping strategies) on the psychological comfort of professional care providers in these two different hospitals. Therefore, a questionnaire survey covering 297 professional care providers working in the two hospitals has been relied upon as a research tool. The findings of the analysis tend to indicate that monobloc professional care providers are more attached to their workplace but they are less satisfied with their working environment than those working in the pavilion hospital. They are more exhausted and more stressed and they rather use the coping strategies which is centred on emotions. The impact of psycho-organisational variables on the psychological comfort of professional care providers depends on the type of hospital.

A l'époque de l'Internet des Objets, le nombre de dispositifs communicants ne cesse d'augmenter. Souvent, les objets connectés utilisent des bandes de fréquences « industriel, scientifique et médical (ISM) » pour effectuer les communications. Ces bandes sont disponibles sans licence, ce qui facilite le déploiement de nouveaux objets connectés. Cependant, cela mène aussi au fait que le niveau d'interférences augmente dans les bandes ISM. Les interférences ont non seulement un impact négatif sur la qualité de service, mais aussi elles causent des pertes de messages couteuses en énergie, ce qui est particulièrement nocif pour les nœuds capteurs souvent limités en énergie. Dans cette thèse, l'impact des interférences sur la consommation énergétique des nœuds est étudié expérimentalement. Les résultats de ces expérimentations sont utilisés pour estimer la durée de vie des nœuds en fonction de différents niveaux d’interférence subis. Puis, un algorithme de Radio Cognitive (RC) basé sur la technique d’ échantillonnage de Thompson est proposé et évalué par la simulation et implémentation. Les résultats montrent que l'approche proposée trouve le meilleur canal plus vite que les autres techniques. De plus, une extension multi sauts pour RC est proposée et évaluée par expérimentation lors d'une compétition EWSN Dependability Competition. Finalement, le protocole adaptatif WildMAC est proposé pour le cas d'usage du projet LIRIMA PREDNET qui consiste à surveiller des animaux sauvages. Les performances sont évaluées par simulation avec le simulateur WSNet. Les résultats montrent que la solution proposée respecte les contraintes imposées par le projet PREDNET dans la zone ciblée. / In the era of the Internet of Things, the number of connected devices is growing dramatically. Often, connected objects use Industrial, Scientific and Medical radio bands for communication. These kinds of bands are available without license, which facilitates development and implementation of new connected objects. However, it also leads to an increased level of interference in these bands. Interference not only negatively affects the Quality of Service, but also causes energy losses, which is especially unfavorable for the energy constrained Wireless Sensor Networks (WSN). In the present thesis the impact of the interference on the energy consumption of the WSN nodes is studied experimentally. The experimental results were used to estimate the lifetime of WSN nodes under conditions of different levels of interference. Then, a Thompson sampling based Cognitive Radio (CR) adaptive solution is proposed and evaluated via both, simulation and hardware implementation. Results show that this approach finds the best channel quicker than other state of the art solutions. An extension for multihop WSN was proposed for this CR solution and evaluated by hardware implementation in the framework of EWSN Dependability Competition. Finally, an adaptive WildMAC MAC layer protocol is proposed for the usecase of the LIRIMA PREDNET wildlife animal tracking project. Obtained field range test data were used to theoretically estimate cell densities and deployment zone coverage in this Low Power Widea Area Network (LPWAN). Then performance of the protocol was evaluated in WSNet simulation. The results show performance that allows to respect PREDNET project requirements with the given coverage.

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