A existência de associações bidirecionais entre o Sistema Nervoso e o Sistema Imune reforça a hipótese de que mudanças no Sistema Nervoso Central (SNC) influenciam a resposta imune e a susceptibilidade orgânica às doenças. De fato, em contextos de estresse físico ou psicológico, glicocorticóides liberados pelo córtex das adrenais e catecolaminas produzidas pelo Sistema Nervoso Autônomo Simpático (SNAS) e pela medula das adrenais, modulam a atividade do Sistema Imune. O estresse psicológico associado no ser humano ao ato de cuidar e conviver com companheiros acometidos por diversos tipos de enfermidades crônicas ou transtornos psíquicos têm sido correlacionado ao aparecimento de alterações comportamentais, tais como depressão e ansiedade, assim como alterações imunes e queda da resistência orgânica às infecções. Em nosso laboratório, camundongos que conviveram por 14 dias com coespecíficos portadores de um tumor ascítico de Ehrlich (TAE) apresentaram importantes alterações comportamentais e de imunidade inata, atribuídas tanto à estimulação do sistema catecolaminérgico central e do SNAS. Desta forma, pareceu-nos relevante estudar mais profundamente e dentro de uma perspectiva neuroimune o envolvimento do SNAS com os efeitos desencadeados pela convivência com dois portadores do TAE usando como ferramentas farmacológicas o propranolol (antagonista -adrenérgico) e o ICI-118,551 (antagonista β2-adrenérgico). Os resultados obtidos mostraram que o bloqueio dos receptores β-adrenérgicos nos animais companheiros do doente: 1) reverteu o comportamento do tipo-ansioso, uma vez que os camundongos voltaram a frequentar a zona central do campo aberto e reduziu a velocidade média dos animais no campo aberto, porém, não alterou de forma significante a distância total percorrida; 2) reverteu a diminuição nos níveis de noradrenalina e aumentou os níveis do metabólito VMA no hipotálamo, mas não alterou o turnover hipotalâmico de noradrenalina ou os níveis de monoaminas e de seus metabólitos no córtex frontal e no bulbo olfatório; 3) não alterou os níveis séricos de corticosterona; 4) não alterou o peso relativo das adrenais; 5) não alterou a contagem de células na medula óssea; 6) modulou a porcentagem de células natural killer (NK) sanguíneas e esplênicas e diminuiu a expressão da molécula CD69 em células NK esplênicas, mas não alterou a expressão da molécula CD69 em células NK sanguíneas; 7) não alterou o burst basal ou induzido por PMA ou por SAPI e a fagocitose de neutrófilos. O bloqueio dos receptores β2-adrenérgicos nos animais companheiros do doente alterou apenas a expressão da molécula CD69 em células NK sanguíneas, mas não modificou de forma significante quaisquer dos parâmetros comportamentais e neuroquímicos analisados. Conclui-se, então, que algumas das alterações imunes e comportamentais desencadeadas pela convivência com coespecíficos portadores de TAE sejam mediadas pelo SNAS via receptores beta-adrenérgicos / The existence of bi-directional interactions between the Nervous System and the Immune System reinforces the hypothesis that changes in Central Nervous System (CNS) activity modify not only the immune response but also the susceptibility to diseases. Indeed, in presence of physical or psychological stress, glucocorticoids released by the cortex of the adrenal gland and catecholamines released by the Autonomic Sympathetic Nervous System (ASNS) activation and the adrenal glands were reported to modulate the activity of the Immune System. Psychological stress was described in human caregivers of sick partners, especially when they present chronic diseases and/or psychological disorders, such as depression and anxiety; immune disorders and decreased host resistance to infections were also reported in caregivers. In our laboratory, Swiss mice that lived for 14 days with Ehrlich ascetic tumor bearing conspecifics showed interesting behavioral and innate immune changes that were attributed to catecholaminergic activation within the Central Nervous System or to ASNS activation. Thus, it seemed relevant to study more deeply and under a neuroimmune perspective the involvement of the ASNS in the effects triggered by cohabitation with two sick partners using as pharmacological tools: propranolol (β-adrenergic antagonist) and ICI-118.551 (β2-adrenergic antagonist). Our results showed that β-adrenergic receptors blockade: 1) reversed the anxiety-like behavior induced by cohabitation, once the animals returned to visit the central area of the open field arena and abrogated the effects of the housing condition on the average speed of locomotion measured in those animals; 2) reversed the decrease in norepinephrine levels and increased VMA levels in the hypothalamus; 3) modulated the percentage of natural killer (NK) cells in both, spleen and blood; also, decreased the expression of CD69 molecule on splenic NK cells. Further analysis showed no changes in: 4) the total distance traveled in the open field; 5) the hypothalamic norepinephrine turnover and the levels of monoamines and their metabolites in the frontal cortex and olfactory bulb; 6) the serum corticosterone levels; 7) the relative adrenal glands; 8) cell number in the bone marrow; 9) the basal oxidative burst or those induced by PMA or SAPI in neutrophils and in neutrophils phagocytosis. The blockade of β2-adrenergic receptors by ICI-118.551 changed only the CD69 expression in NK blood cells, being unable to modify any of the behavioral and neurochemical parameters analyzed. Therefore, it seems that only some of the immune and behavioral changes triggered by cohabitation with two sick partners present a relevant participation of SNAS through beta-adrenergic receptors

In OFDM systems carrier frequency offset is observed due to Doppler shift and transmitter-receiver frequency mismatches. This offset induces ICI (Intercarrier Interference). In this thesis, repeated data methods and pilot-aided carrier frequency offset(CFO) estimation methods and windowing techniques are used to mitigate the frequency offset problem and a performance comparison is made between these ICI cancellation techniques. Repeated data methods use only half of the bandwidth for information transmission to eliminate the ICI at the receiver. We have implemented repeated data methods including Self cancellation scheme and Symmetric Symbol Repetition (SSR) schemes to overcome ICI problem. We have also implemented Adjacent Conjugate Symbol Repetiton (ACSR) and Symmetric Conjugate Symbol Repetiton (SCSR) methods to mitigate both phase rotations and ICI. CFO estimation and correction methods generally use pilot sequences. We implemented the &ldquo / Conventional Pilots&rdquo / and &ldquo / Clustered Pilots&rdquo / pilot-aided CFO estimation techniques for ICI cancellation. Furthermore, we also implemented a new scheme by using the odd symmetry between pilot symbols. Nyquist windowing techniques apply windowing at the receiver side. We have implemented second order polynomial class of Nyquist windows and Nyquist window with Franks pulse used to mitigate ICI. These ICI cancellation methods are compared in AWGN and multipath Rayleigh fading channel models in terms of BER and carrier to interference ratio. It is shown that repeated data methods shows better performances than pilot-aided CFO estimation methods with a cost of increased bandwidth usage especially in high SNR&rsquo / s.

In this thesis, we investigate a wireless communications system with distributed transmit antennas. Under such system scenario, the received signal has multiple carrier frequency offsets (CFOs) since each transmitter has its own oscillator, leading to serious inter-carrier interference (ICI) at the receiver end. Therefore, an ICI self-cancellation scheme is proposed in this thesis, where two different relay nodes use different sub-carriers. When the signals from different relay nodes are combined at the destination node, the ICI self-cancellation can be achieved. In addition, the quality of the received signal can be further improved if the residual CFO can be properly compensated. Traditionally, the medium value of the various CFOs is taken for compensation because of its simplicity. However, a medium value does not result in the optimal performance. In this thesis, a close form expression of optimal CFO is derived to maximize the average signal to interference power ratio. It is shown that the optimal CFO compensation is a function of channel state and individual CFOs. Simulation experiments are conducted to investigate the performance of the proposed scheme. It is shown that the system bit error rate can be substantially improved when the CFO is less than 0.3 subcarrier spacing.

ITC/USA 2013 Conference Proceedings / The Forty-Ninth Annual International Telemetering Conference and Technical Exhibition / October 21-24, 2013 / Bally's Hotel & Convention Center, Las Vegas, NV / Systems using single carrier modulations for flight test transmissions perfectly fit noisy and time selective channels. However, the densification of the airport environment now makes the aero channel also frequency selective due to multiple reflections on surrounding buildings, especially while taxiing and taking off. Obviously, this has a direct consequence on hardware resources and user data rates. In such a context, COFDM represents an appealing solution thanks to its inherent robustness to multipath fading channels. But a direct application of an off-the-shelf COFDM standard is not straightforward as these standards are designed for specific channels whose characteristics are quite different from the aero one. That is why we made an experiment at Toulouse-Blagnac airport to jointly sound the channel and qualify a COFDM waveform. This paper then describes the construction of the waveform and the results of the channel sounding. From this, different standard paradigms are compared.

In order to support the new paradigm shift in fifth generation (5G) mobile communication, radically different network architectures, associated technologies and network operation algorithms, need to be developed compared to existing fourth generation (4G) cellular solutions. The evolution toward 5G mobile networks will be characterized by an increasing number of wireless devices, increasing device and service complexity, and the requirement to access mobile services ubiquitously. To realise the dramatic increase in data rates in particular, research is focused on improving the capacity of current, Long Term Evolution (LTE)-based, 4G network standards, before radical changes are exploited which could include acquiring additional spectrum. The LTE network has a reuse factor of one; hence neighbouring cells/sectors use the same spectrum, therefore making the cell-edge users vulnerable to heavy inter cell interference in addition to the other factors such as fading and path-loss. In this direction, this thesis focuses on improving the performance of cell-edge users in LTE and LTE-Advanced networks by initially implementing a new Coordinated Multi-Point (CoMP) technique to support future 5G networks using smart antennas to mitigate cell-edge user interference in uplink. Successively a novel cooperative uplink inter-cell interference mitigation algorithm based on joint reception at the base station using receiver adaptive beamforming is investigated. Subsequently interference mitigation in a heterogeneous environment for inter Device-to-Device (D2D) communication underlaying cellular network is investigated as the enabling technology for maximising resource block (RB) utilisation in emerging 5G networks. The proximity of users in a network, achieving higher data rates with maximum RB utilisation (as the technology reuses the cellular RB simultaneously), while taking some load off the evolved Node B (eNodeB) i.e. by direct communication between User Equipment (UE), has been explored. Simulation results show that the proximity and transmission power of D2D transmission yields high performance gains for D2D receivers, which was demonstrated to be better than that of cellular UEs with better channel conditions or in close proximity to the eNodeB in the network. It is finally demonstrated that the application, as an extension to the above, of a novel receiver beamforming technique to reduce interference from D2D users, can further enhance network performance. To be able to develop the aforementioned technologies and evaluate the performance of new algorithms in emerging network scenarios, a beyond the-state-of-the-art LTE system-level-simulator (SLS) was implemented. The new simulator includes Multiple-Input Multiple-Output (MIMO) antenna functionalities, comprehensive channel models (such as Wireless World initiative New Radio II i.e. WINNER II) and adaptive modulation and coding schemes to accurately emulate the LTE and LTE-A network standards.

Cette thèse analyse comment le déplacement, autant géographique qu’ontologique, est mis en scène dans trois recueils de poésie issus de la francophonie canadienne, soit La Voyageuse d’Andrée Lacelle, Rues étrangères de Sarah Marylou Brideau et Poste restante : cartes poétiques du Sénégal de Lise Gaboury-Diallo. Le premier chapitre explore comment l’ici est construit poétiquement au sein des trois recueils et comment celui-ci diffère, ou non, de l’ici réel de la communauté d’appartenance de la poète. Le deuxième chapitre examine comment les personnages-poètes transitent de l’ici vers l’ailleurs; j’y étudie comment cet espace transitoire et le voyage dans l’entre-deux sont représentés. Je tente aussi de déterminer si le voyage physique va de pair avec un cheminement psychologique. Enfin, le troisième chapitre porte sur les diverses rencontres avec l’altérité qui découlent des voyages. Je montre qu’elles permettent aux personnages-poètes de redéfinir leur identité et de se (re)constituer un soi qui leur est propre.

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