Un análisis de facies detallado se llevó a cabo en los depósitos fluviales del Grupo Chubut y marinos de la Fm La Colonia que se exponen en el Noreste de la Provincia de Chubut. La Formación Marifil representa las rocas ígneas más antiguas en el área, constituye el basamento sedimentario y perfiles geoeléctricos del subsuelo, determinaron un desarrollo irregular del mismo. Un conjunto de elementos arquitectura-les caracterizan al sistema fluvial del Grupo Chubut: lacustre expuesto sólo al norte, y elementos de canal, faja de canales y de llanura de inundación al sur. Estos últimos, presentan una progresiva variación desde abanicos aluviales en la base, sistemas entrelazados y sistemas de canales arenosos en cinta, depositados en sucesivos episodios con depósitos de desborde. En el tramo superior de la sucesión se reconocieron cinturones meandrosos poco desarrollados y canales aislados, culminando con un importante desarrollo de elementos de llanura de inundación. Asociado a los depósitos de llanura de inundación, se reconocieron rasgos post-depositacionales vinculados con procesos de licuefacción/fluidización, rela-cionados con una etapa de telodiagénesis. Una sucesión vertical de 4,5 m, comprende cuatro intervalos bien definidos: fragmentado in situ, brechado, brechado fango sostenido y superior homogéneo, con potenciales conductos de escape, Constituyen un ejemplo excepcional de desarrollo natural de brechamiento en un medio frágil y los mecanismos dispara-dores podrían estar asociados a actividad sísmica o a impacto de bólidos. A partir del análisis de circones detríticos, se determinó para el Grupo Chubut una edad máxima de deposi-tación albiana, ca. 106 Ma en la localidad de Telsen y ca. 109 Ma en el sector Cañadón Williams. Las fuentes de procedencia para el Grupo corresponden principalmente a la Formación Marifil, cuya edad quedó acotada para el área entre 182 y 188 Ma. La comparación de los datos jurásicos en las dos muestras analizadas, sugiere una modificación progresiva desde el NE al E-SE del sector de aporte al Grupo Chubut. En contacto neto erosivo sobre el Grupo Chubut, se dispone asociado a la Fm La Colonia, un conglomerado tabular basal, que representa una superficie de ravinamiento, de impor-tancia significativa en la estratigrafía secuencial. Fue interpretada como una superficie transgresiva que evidencia para el área de Telsen el comienzo de la ingresión maastri-chtiana. Le suceden hacia arriba, asociaciones de facies de frente de playa a off shore, intermareal (llanura mixta y llanura fangosa), lagunas con influencia marina y lagunas sin aparente conexión marina en el sector supramareal, con esporádicas intercalaciones arenosas con estructura de domo y cuenco en la base. Se indicaron para la Fm La Colonia ambientes restringidos de baja energía, asociados a una costa fangosa, afectada por episodios de tormenta. Considerando el hiato que media entre el Grupo Chubut (Albiano) y Fm La Colonia (Maastrichtiano/Daniano), se propone considerar como Formación La Colonia, al conjunto de pelitas verdosas a grisáceas, de origen marino, ubicadas por encima de la super-ficie transgresiva, mientras que las pelitas continentales por debajo de esta superficie, hasta el momento pertenecientes a la Fm La Colonia, quedarían incluidas en el Grupo Chubut. Una discontinuidad de bajo ángulo, con una inclinación de aproximadamente 0.5%, que trunca al Grupo Chubut y a la Formación La Colonia fue reconocida en el área. Un mapeo de semidetalle de las unidades geológicas y un mapeo de detalle de los paleoambientes, complementan la información cartográfica preexistente. / A detailed facies analysis was performed on the fluvial deposits of the Chubut Group as well as on the marine deposits of La Colonia Formation, both located at Northeast-Chubut Province. The Marifil Formation represents the older igneous rocks in the area, constitutes the sedimen-tary basement and geolectric profiles determined an irregular morphology for the subsurface deposits of the unit. The fluvial system of the Chubut Group is characterized by a number of architectural elements: lacunar in the North, and channel, channel belt and floodplain elements in the South. The last elements, as exposed in a vertical succession, vary progressively from alluvial fans in the bottom, braided systems and multistorey sandstone- dominated ribbon channels with crevasse splay deposits. The upper part of the succession evidences poorly developed meander belts and isolated channels, ending with a significant development of the flood-plain elements. Post-depositional features recognized in the floodplain deposits evidence liquefaction/fluidization pro-cesses and they were associated with a telodiagenetic stage. The 4,5m vertical succession comprises four well-defined intervals: fractured, brecciation, mud-rich breccias and upper fully shared, including potential escape conduits. They represent an exceptional example of naturally developed brecciation in a brittle medium. These processes may have been originated by seismic activity or bolides impact. The analysis of detrital zircon yielded the Aptian as the maximum depositional age for the Chubut Group, ca. 106 Ma in Telsen, and ca. 109 Ma in the Cañadón Williams area. The sources for the Chubut Group correspond mainly to the Marifil Formation, whose age in the area was restricted between 182 and 188 Ma. Comparing the Jurassic data in the two samples analyzed, suggests a progressive modification of the Chubut Group source area from the NE to E-SE. Associated to the La Colonia Formation deposits, a basal tabular conglomerate, lying in sharp erosive contact with the Chubut Group, repre-sents a ravinement surface and constitutes a key surface from a sequence stratigraphy approach. It was interpreted as a transgressive surface and evidences the beginning of the Maastrichtian ingression for the area. Upwardly, this surface is succeeded by facies associations related to shoreface to offshore, intertidal (mixed and mud flat), lagoons under marine influence and lagoons with no apparent marine relation in the supratidal zone. Low-energy restricted environments, associated with a muddy coast affected by storm episodes, were interpreted for the La Colonia Formation. Taking into account the hiatus between the Chubut Group (Albian) and the La Colonia Formation (Maastrichtian/Danian), is herein proposed, that the latter ought to be associated with the set of marine greenish-gray mudstones on top of the trans-gressive surface, while the continental mudstones under this surface -related up to now to La Colonia Formation- should be included in the Chubut Group. A lowangle discontinuity that cut across the Chubut Group and La Colonia Formation, of about 0.5%, was recognized in the area. A semi-detailed mapping of the geological units and a detailed-mapping of the palaeoenvironments, complement the cartographic information available.

Bakgrund: Vid medelåldern drabbas många individer av muskuloskeletala sjukdomar som kan förebyggas och rehabiliteras genom styrketräning. Studier har gjorts på vad som motiverar människor till fysisk aktivitet men är bristfällig gällande motivation till styrketräning. Syfte: Syftet med studien var att undersöka vilka faktorer som motiverar styrketränande personer i medelåldern till att styrketräna, samt att redogöra för hur kön, grupp- och individuell träning, träningsvolym och hur länge en person styrketränat påverkar motivationsfaktorerna. Metod: Femtiofem personer mellan 40-60 år besvarade ett digitalt frågeformulär om vad som motiverar dem till att styrketräna. En del av enkäten innehöll bakgrundsfrågor om deltagarna. Den andra delen innefattade en modifierad version av formuläret RM 4-FM. Resultat: Deltagarna drevs främst av inre motivation och identified regulation. Det fanns en signifikant skillnad i typ av motivation mellan könen, där kvinnorna skattade högre på frågor gällande identified regulation (p=.028). Det fanns ingen signifikant skillnad mellan personer som tränade individuellt eller i grupp (external regulation: p=.500, introjected regulation: p= .517, identified regulation: p=.391, intrinsic regulation: p=.918) och inget samband mellan antal tränade timmar per vecka (p=.109) eller hur länge en person har styrketränat (p=.663) med relative autonomy index (RAI. Konklusion: Resultaten ger insikt i att personer i medelåldern drivs mer av inre motivation till styrketräning och att kvinnor tenderar att motiveras mer av inre drivkrafter, men kan inte generaliseras till hela populationen. Fortsatt forskning krävs för att undersöka relationen mellan motivation och styrketräning hos personer i medelåldern. / Background: During the middle-age, it is common to obtain a variety of musculoskeletal conditions, however, strength training reduces the risk to obtain these complications. There are many studies with the goal to research motivational factors that contribute to physical activity, however, there are few studies that have similar objectives related to strength training.  Objective: The objective of this study was to better understand what motivates middle aged individuals to strength train.  Method: In this study, 55 participants between 40 to 60 years old, completed a questionnaire about motivational factors to strength training. The first part consisted of background questions and the second part, a modified version of the RM 4-FM questionnaire.  Results: The results from the questionnaire showed that a majority of the sample were driven by intrinsic motivation and more specifically identified regulation. Group comparisons showed that women on average scored higher on the questions related to identified regulation (p=.028). There were no significant differences between individuals who train individually or in group (external regulation: p=.500, introjected regulation: p= .517, identified regulation: p=.391, intrinsic regulation: p=.918) nor seen in correlation between training volume (p=.109) and training experience (p=.663) with RAI. Conclusion: The results of this study show that individuals who strength train are predominantly incentivised by intrinsic motivation and women tend to have a stronger intrinsic motivation than men, however further research is required to continue to explore the complex relationship between motivation and strength training habits.

Logging of cores of the Upper Permian and Lower Triassic Khuff Formation, Ghawar, Saudi Arabia, has allowed a high resolution sequence stratigraphic framework to be generated. The lithofacies of this huge, arid epeiric ramp succession include: subaqueous -and supratidal anhydrite, tidal flat laminites, lagoonal mudstone, ooid-peloid grainstone, and subtidal off-shoal open marine mudstone. Third order sequences include the Late Permian upper Khuff C, the Early Triassic Khuff B and the Khuff A sequences, which corrrelate with global cycles. Seven high frequency sequences (HFSs) make up the Changhsingian upper Khuff C. These HFSs are ~400 k.y. duration and probably driven by long term eccentricity. The Early Triassic Khuff B and A sequences are made up of 4 HFSs each, which appear to be ~100 to 200 k.y. duration and not easily tied to eccentricity forcing. The HFSs are in turn composed of parasequences, which appear to be 10 to 20 k.y. average durations, suggesting precessional and half precessional forcing. However, many thin locally developed cycles may be autocycles or subprecessional cycles. Sequence stratigraphic cross sections and facies maps document progradation directions on the platform, reflecting the subtle interplay between the Ghawar structure and regional paleoslopes. Anhydrites are rare in the Permian Upper Khuff C except near the base of the studied interval. Anhydrites are well developed in the Triassic Khuff B and Khuff A where some form transgressive deposits while others are highstand deposits of high frequency sequences. The Permian-Triassic boundary (PTB) on the Arabian Platform marks a significant relative sea-level drop, that exposed from the outcrop belt to somewhere east of Ghawar. This contrasts with transgressive PTB settings elsewhere. Across the PTB the mass extinction is marked by a major decrease in biotic groups. The extinction was followed by development of subtidal thrombolites and increased microbial calcification due to decreased bioskeletonization. The dominant reservoirs in the Permian Upper Khuff C occur in oolite in the uppermost high frequency sequence. In the Triassic Khuff B and A the reservoir facies are commonly non-dolomitized oolitic facies associated with open lagoon carbonates distant from evaporitic tidal flats. Within dolomitized units, best reservoirs are associated with oomoldic porosity, but oolite units proximal to evaporitic tidal flats have porosity plugged by anhydrite. Carbon and oxgyen isotope profiles up to 150 m long were obtained from cored wells of the Khuff Formation, Ghawar Field, Saudi Arabia, across the Permian-Triassic boundary. Major global excursions are at the Changhsingian-Wuchiapingian boundary and the Permian-Triassic boundary, but several smaller excursions also appear to correlate with excursions elsewhere. The presence of the negative C-isotope excursions globally in both δ¹³Ccarbonate and δ¹³C organic as well as in deeper water sections lacking emergence surfaces, strongly supports the idea of these excursions being global phenomena related global C cycling. Over 75% of the negative carbon isotope excursions in Ghawar occur beneath emergence surfaces, including the two major excursions at the Wuchiapingian and Changhsingian stage boundaries. The δ¹³C profiles beneath the boundaries resemble those iii associated with early diagenesis associated with isotopically light soil gas. The δ¹⁸O profiles beneath the surfaces are variable, perhaps reflecting variable effects of evaporation on the meteoric input, mixing or overprinting by burial diagenesis. This suggests that the C-isotope excursions on the Arabian Platform, although global in origin, appear to have been modified by early diagenesis. U depletion across the boundary is compatible with the postulated origins of the PTB event with bottom waters becoming stagnant and reducing, as a result of warming induced by volcanogenic CO₂ released by Siberian trap volcanism, methane release from thermal metamorphism of coals and destabilization of clathrates in the deep sea due to ocean warming. The global extent of the C-isotope and U excursions provides a high resolution correlation tool for Late Permian and Early Triassic successions. / Ph. D.

The wireless communications industry has experienced tremendous growth worldwide in the past decade. Numerous cellular communication systems have been developed to meet this need. In North America, AMPS, IS-54, 1S-95 and GSM are the most popular cellular systems ruling the market. In developing nations, Wireless Local Loop (WLL) services will be in great demand in the coming years. While some service providers may adapt existing cellular standards to this application, WLL does not require the support for mobility which is available in a full cellular system. As a result, substantial cost savings may be obtained through dedicated WLL implementations. In this thesis, a new wireless communication system is investigated. The system combines the low cost and flexibility of analog frequency modulation with the capacity and multipath advantages of a Code Division Multiple Access (CDMA) system. This system aims to provide WLL telephone services at low cost, with wireline grade voice quality, fast infrastructure deployment and ease of planning. In this thesis, a theory for FM/CDMA system performance is established. Closed form analytical expressions of signal to multiple. access interference ratio are obtained using both upper bounds and lower bounds. The hybrid system is also optimized for the optimum combination of modulation index and processing gain. In addition, a software test-bed is developed to model different FM demodulation schemes, evaluate the tradeoff of FM modulation index versus CDMA processing gain and the system robustness, compare the forward link and the reverse link system performance and investigate the effect of power control schemes. / Master of Science

Utilizing Building Information Modeling (BIM) for Facility Management (FM) can reduce interoperability costs during the Operations and Maintenance (OandM) phase by improving data management. However, there are technological, process related, and organizational barriers to successful implementation of BIM integrated FM (BIM-FM), and process related barriers might be solved by the use of BIM integrated FM (BIM-FM) guidelines. However, the guidelines need to be updated with lessons learned from actual practices in order to maintain their validity. In order to diagnose current practices and identify key differences between prescriptive representations and actual practices, this exploratory research compares BIM component data requirements between guidelines and actual practices at public higher education institutions in Virginia. The gap in BIM component data requirements between the guidelines and the actual practices may prevent successful implementation of BIM-FM. This research is composed of three parts: a synthesis of prescriptive representations, determination of actual data requirements in practice, and comparison of differences between guidelines and practices. Document analysis and case study via document analysis and in-person interviews were conducted to collect data. Then, direct comparison was conducted to test the research question. Though the researcher disapproved the established hypothesis of 'There would be some differences in BIM component data requirements between prescriptive representations and actual practices' due to the difference in level of information and details between prescriptive representations and actual practices, this exploratory research provides useful information. / Master of Science

L’ouverture du secteur audiovisuel camerounais a consacré l’avancée du processus d’acquisition et de l’octroi des libertés individuelles commencé autour des années 1990. Le décret d’application d’avril 2003 a entériné une dizaine d’années plus tard, le dispositif enclenché par la loi n°90-052 du 19 décembre 1990 relative à la liberté de communication sociale. Depuis lors, organes de presse et audiovisuels se côtoient et se heurtent à des pesanteurs susceptibles de limiter leur efficacité, en tant qu’outils et moyens de communication de proximité. Leur jeunesse, les problèmes endogènes et exogènes au paysage médiatique camerounais justifierait une étude sur l’existence et la manière dont les organes de communication sociale produisent et diffusent informations et nouvelles en direction des populations ciblées. A ce sujet, la radio communautaire, tout en cherchant à les impliquer et à les faire participer à cet objectif de communication sociale, promeut par ses programmes, la propre image des populations à laquelle elle est destinée. Il ne reste qu’à garantir les modalités pratiques, les conditions nécessaires pour une participation transparente des différents acteurs à la gestion et au fonctionnement de la radio. Pour une grande part, les populations sont prêtes à soutenir les projets de radios communautaires qui s’installent dans les localités. Les différentes techniques d’appropriation et d’usage des médias permettent d’appréhender de l’extérieur les différents enjeux qui se tissent. Elles permettent d’observer les pratiques mises en place et les conditions d’engagement des acteurs sociaux pour garantir, une longue vie à la radio. / The opening of the Cameroonian audiovisual sector dedicated the overhang of the process of acquisition and the granting of the personal freedoms begun around 1990s. The application decree of April, 2003 confirmed a decade later, the plan engaged by the law 90/052 of December 19th, 1990 relative to the freedom of social communication. Since then, newspapers and broadcasting mix and come up against gravities susceptible to limit their efficiency, as tools and means of communication of nearness. Their youth, the endogenous and exogenous problems in the Cameroonian media landscape justify a study on the existence and the way the organs of social communication produce and broadcast information and news in the direction of the targeted populations. For this subject, the community radio, while trying to imply them and to make them participate in this objective of social communication, promotes by its programs, the own image of the populations for which is intended. It remains only to guarantee the practical methods, the necessary conditions for a transparent participation of the various actors in the management and in the functioning of the radio. Mostly, the populations are ready of supporting the projects of community radios which settle down in villages. The various techniques of appropriation and uses of the media allow dreading from the outside the various stakes which weave. They allow observing the organized practices and the conditions of commitment of the civil society to guarantee, a long life on the radio.

Fusarium-Infektionen sind ein ernstes Problem im Weizenanbau, da die ausgeschiedenen Mykotoxine gesundheitsschädlich sind. Die Krankheitssymptome sind durch bildanalytische Methoden im Vorfeld der Ernte detektierbar, so dass befallene Partien getrennt geerntet werden könnten. Künstlich mit Fusarium culmorum infizierte Weizenpflanzen wurden mittels Chlorophyllfluoreszenz- und hyperspektraler Bildanalyse in Zeitreihenversuchen analysiert. Bei den Chlorophyllfluoreszenz-Bildanalysen wurde die photosynthetische Effizienz (Fv/Fm) und deren räumliche Ungleichverteilung genutzt, um den Effekt des Krankheitsgrades auf die photosynthetische Aktivität zu ermitteln. Mit dieser Methode ist eine sehr frühzeitige Erkennung möglich, da eine Verringerung der photosynthetischen Effizienz bei den kranken Ähren zwischen dem 6. und 11. Tag nach Inokulation festgestellt wurde. Der Befallsgrad korreliert mit der photosynthetischen Effizienz. Die Berechnung des kumulativen Fv/Fm bei 0,3 führte zu einer sehr effektiven und genauen Erkennung der Partiellen Taubährigkeit ab einem Befallsgrad von mindestens 5% und einer Differenzierungsgenauigkeit von 10%. Die Chlorophyllfluoreszenz-Bildanalyse war unter Freilandbedingungen bei Einhaltung der Rahmenbedingungen zur Fusarium-Erkennung ebenfalls möglich, wenn auch mit schlechteren Erkennungsraten. Die Aufnahmen im Labor mit einem hyperspektralen Bildanalysesystem im Spektralbereich von 400-1000 nm zeigten Unterschiede in distinkten Wellenlängenbereichen und lassen die Erkennung kranker Ähren in einem Zeitfenster von BBCH 71 bis BBCH 85 zu. Die bildanalytische Klassifizierung mittels des „Spectral Angle Mapper“ liefert gute Ergebnisse, ist aber sehr zeitaufwändig. Alternativ dazu nutzt der neu erstellte head blight-Index (HBI) die spektralen Unterschiede im Bereich 665-675 nm und 550-560 nm und kann eine feldtaugliche Klassifizierungsmöglichkeit zur Erkennung von Partieller Taubährigkeit sein. / Fusarium infections are serious problems in wheat production. Mycotoxins, synthesised by the fungi, are toxic and harmful in both human and animal nutrition. The symptoms of this so-called head blight disease caused by Fusarium spp. are recognizable by various image analysis methods prior to harvest. Using this information, farmer could differently utilize affected cereals, if necessary. Healthy and artificially Fusarium culmorum-infected wheat plants were analyzed with a chlorophyll fluorescence and hyper-spectral imaging system in time series. With chlorophyll fluorescence imaging (CFA), the potential maximum photochemical efficiency (Fv/Fm) and its spatially variable distribution was analyzed to determine the interactions between the degree of disease and the photosynthetic activity. By means of this method, early recognition was reliably achieved by a decreased photochemical efficiency in diseased ears between 6th and 11th day after inoculation. The degree of disease correlated with photochemical efficiency. At a degree of Fusarium infection of 5% and higher, calculation of the cumulative Fv/Fm at 0.3 enabled a very effective and precise determination of Fusarium head blight with a differentiation accuracy of at least 10%. Though less effective, CFA successfully detected head blight under outdoor conditions, if some boundary conditions (e.g. no direct solar irradiation) were observed. In the laboratory, a hyperspectral imaging system (wave length range 400 to 1000 nm) indicated specific spectral differences between affected and unaffected wheat ears. These differences allowed head blight recognition during BBCH 71 to BBCH 85. Imaging classification with the “Spectral Angle Mapper” method achieved good results; it is, however, very time-consuming. Alternatively, the newly derived head blight index (HBI), using spectral differences in the wave length ranges of 665 to 675 nm and 550 to 560 nm, can be a suitable outdoor classification method to evaluate head blight.

Ce travail de thèse concerne le traitement d’image fDOT (fDOT pour fluorescence diffuse optical tomography) suit vers deux axes. Le recalage d'images fDOT à l’aide de l’imagerie TEP (tomographie par émission de positons) et l’amélioration des reconstructions fDOT à l’aide de miroirs pour collecter des projections complémentaires. Il est présenté en deux parties : Dans la première partie, une méthode automatique pour recaler les images de fDOT avec les images de Tomographie par Emission de Positons (TEP) développée dans le but de corréler l’ensemble des informations issues de chaque modalité. Cette méthode de recalage est basée sur une détection automatique de marqueurs fiduciaires présents dans les deux modalités. La particularité de cette méthode est l’utilisation de l’image de surface obtenue en fDOT, qui sert à identifier la position en Z des marqueurs fiduciaires dans les images optiques. Nous avons testé cette méthode sur un modèle de souris porteuses de xénogreffes de tumeurs de cellules cancéreuses MEN2A qui imitent un carcinome thyroïdien médullaire humain, après une double injection de traceur radioactif : [18F]2-fluoro-2-Deoxy-D-glucose (FDG) pour l’imagerie TEP et un traceur optique d’infrarouge fluorescent, le Sentidye. Grâce à la précision de notre méthode, nous arrivons à démontrer que le signal Sentidye est présent à la fois dans la tumeur et les vaisseaux environnants [1]. La qualité des images fDOT est dégradée selon l’axe Z du fait d’un nombre limité de projections pour la reconstruction. Dans la deuxième partie, le travail s’est orienté vers une nouvelle méthode de reconstruction d’images fDOT à partir d’un nouveau système d’acquisition multi-angulaire avec deux miroirs placés de chaque côté de l’animal. Ce travail a été mené en collaboration avec le département CS d’University College London (UCL), partenaire du projet Européen FMT-XCT. Le logiciel TOAST développé par cette équipe a été utilisé comme source pour l’algorithme de reconstruction, et modifié pour s’adapter à notre problématique. Après plusieurs essais concernant l’ajustement des paramètres du programme, nous avons appliqué cette méthode sur un fantôme réaliste des tissus biologiques et chez la souris. Les résultats montrent une amélioration de l’image reconstruite d’un fantôme semi-cylindrique et de l’image de rein chez la souris, pour lesquelles la méthode des miroirs est supérieure à la méthode classique sans miroir. Malgré tout, nous avons observé que les résultats étaient très sensibles à certains paramètres, d’où une performance de reconstruction variable d’un cas à l’autre. Les perspectives futures concernent l’optimisation des paramètres afin de généraliser l’approche multi-angle. / This thesis concerns the image processing of fluorescence diffuse optical tomography (fDOT), following two axes: FDOT image co-registration with PET (positron emission tomography) image and improvement of fDOT image reconstructions using mirrors to collect additional projections. It is presented in two parts:In the first part, an automatic method to co-register the fDOT images with PET images has been developed to correlate all the information from each modality. This co-registration method is based on automatic detection of fiducial markers (FM) present in both modalities. The particularity of this method is the use of optical surface image obtained in fDOT imaging system, which serves to identify the Z position of FM in optical images. We tested this method on a model of mice bearing tumor xenografts of MEN2A cancer cells that mimic a human medullary thyroid carcinoma, after a double injection of radiotracer [18F] 2-fluoro-2-Deoxy-D-glucose ( FDG) for PET imaging and optical fluorescent infrared tracer Sentidye. With the accuracy of our method, we can demonstrate that the signal of Sentidye is present both in the tumor and surrounding vessels.The fDOT reconstruction image quality is degraded along the Z axis due to a limited number of projections for reconstruction. In the second part, the work is oriented towards a new method of fDOT image reconstruction with a new multi-angle data acquisition system in placing two mirrors on each side of the animal. This work was conducted in collaboration with the CS Department of University College London (UCL), a partner of the European project FMT-XCT. TOAST software developed by this team was used as source code for the reconstruction algorithm, and was modified to adapt to the concerned problem. After several tests on the adjustment of program parameters, we applied this method on a phantom that simulating the biological tissue and on mice. The results showed an improvement in the reconstructed image of a semi-cylindrical phantom and the image of mouse kidney, for which the reconstruction of the mirrors geometry is better than that of conventional geometry without mirror. Nevertheless, we observed that the results were very sensitive to certain parameters, where the performance of reconstruction varies from one case to another. Future prospectives concern the optimization of parameters in order to generalize the multi-angle approach.

Dans le contexte de la fusion par confinement inertiel (FCI), le lissage optique est une technique utilisée pour obtenir une irradiation laser aussi homogène que possible, en modifiant les propriétés de cohérence temporelle et spatiale des faisceaux laser. L'utilisation du lissage optique est une nécessité sur les lasers de puissance comme le Laser MégaJoule (LMJ) pour limiter le développement des instabilités paramétriques issues de l'intéraction laser-plasma, et parmi elles, la rétrodiffusion Brillouin stimulée (RBS). Ces instabilités entraînent des défauts d'irradiation sur cible et peuvent aussi être une source d'endommagement dans la chaîne optique. Cependant ces techniques peuvent entraîner d'autres problèmes au niveau de la chaîne laser, tels que la conversion de modulation de phase en modulation d'amplitude (FM-AM), néfastes au bon déroulement des expériences et pouvant également endommager les chaînes laser.On comprend donc qu'il est nécessaire de trouver un compromis autour du lissage optique. L’évolution du compromis du lissage est cependant compliquée car la quantification des gains et des pertes est très difficile à établir. Ainsi, tant que la quantification n’est pas faite, le compromis n’évolue pas : le lasériste souhaite toujours moins de lissage et « l’expérimentateur » toujours plus de lissage mais aucun des deux ne peut apporter suffisamment d’éléments quantitatifs pour faire pencher la balance. Cette thèse propose donc de poser les premières briques permettant d'arriver à ce compromis pour le LMJ, à l'aide d'études théoriques et numériques.Nous comparons soigneusement le lissage longitudinal (LSSD) et transversal (TSSD) par dispersion spectrale dans une configuration de lissage idéale pour chaque cas. Avec des codes 3D, nous avons simulé la RBS dans un plasma d'or, typique des expériences de FCI et favorable au développement de la RBS. Nous montrons que, contrairement aux idées reçues, l'évolution temporelle de la RBS présente certaines différences entre les deux systèmes de lissage. Premièrement, les valeurs asymptotiques des niveaux de saturation ne sont pas tout à fait les mêmes. Avec une simple description des rayons et le calcul du gain RBS pour chaque rayon, nous avons pu expliquer cette différence. En outre, la dynamique de la RBS est également quelque peu différente. Nous avons montré que la dynamique RBS est déterminée par l'évolution temporelle des propriétés des surintensités et en particulier par la longueur d'interaction effective entre la lumière rétrodiffusée Brillouin et les points chauds. Cette longueur d'interaction effective dépend à la fois de la vitesse longitudinale et de la longueur des points chauds. En effet, la synchronisation des longueurs d'interaction effectives des deux schémas de lissage synchronise également la croissance des courbes de rétrodiffusion avant saturation.Nous montrons, également qu'il est possible de faire évoluer les paramètres de lissage du LMJ en illustrant une nouvelle façon de réduire la conversion FM-AM inévitablement présente dans les lasers de forte puissance. En répartissant le spectre total habituellement utilisé par un quadruplet (regroupement de 4 faisceaux), en deux parties de spectres identiques plus petits sur les faisceaux de gauche et de droite, la conversion FM en AM est considérablement réduite de 30% à 5% tout en maintenant la performance de lissage pour la RBS. Nous avons également montré que le temps de cohérence qui en résulte n'a aucun effet sur le niveau maximal de RBS atteint. De la même façon, il faudra étudier l'impact de ces évolutions sur d'autres instabilités telles que le diffusion Raman stimulée ou le transfert d'énergie par croisement de faisceaux. / In the context of inertial confinement fusion (ICF), optical smoothing is a technique used to obtain the most homogeneous laser irradiation possible, by modifying the temporal and spatial coherence properties of the laser beams. The use of optical smoothing is a necessity on high-power lasers such as the Laser Mégajoule (LMJ) to limit the development of parametric instabilities resulting from laser-plasma interaction, and among them, stimulated Brillouin backscattering (SBS). These instabilities lead to target irradiation defects and can also be a source of damage in the optical lines. However, these techniques can lead to other problems in the laser lines, such as the conversion of phase modulation to amplitude modulation (FM-to-AM), which is harmful to the proper conduct of the experiments and can also damage the laser optics.It is therefore a necessity to find a compromise around optical smoothing. The evolution of the smoothing compromise is however complicated because the quantification of gains and losses is very difficult to establish. Thus, as long as quantification is not done, the compromise does not evolve: the laserist always wants less smoothing and the experimentalist always more smoothing, but neither of them can bring enough quantitative elements to tip the balance. This thesis therefore proposes to lay the first groundwork for reaching this compromise for the LMJ, using theoretical and numerical studies.We carefully compare longitudinal (LSSD) and transverse (TSSD) smoothing by spectral dispersion in an ideal smoothing configuration for each case. With 3D codes, we simulated SBS in a gold plasma, typical of ICF experiments and favourable to the development of SBS. We show that, contrary to popular belief, the temporal evolution of SBS shows some differences between the two smoothing schemes. First, the asymptotic values of saturation levels are not quite the same. With a simple description using light rays and the calculation of the SBS gain for each ray, we were able to explain this difference. In addition, the dynamics of SBS are also somewhat different. We have shown that the SBS dynamics is determined by the temporal evolution of the properties of the hot-spots and in particular by the effective interaction length between the Brillouin backscattered light and the hot-spots. This effective interaction length depends on both the longitudinal velocity and the length of the hot-spots. Indeed, the synchronization of the effective interaction lengths of the two smoothing schemes also synchronizes the growth of the backscatter curves before saturation.We also show that it is possible to change the smoothing parameters of the LMJ by illustrating a new way to reduce the FM-to-AM conversion inevitably present in high-power lasers. By splitting the total spectrum usually used by a quadruplet (grouping of 4 beams) into two parts of smaller identical spectra on the left and right beams, the FM-to-AM conversion is significantly reduced from 30% to 5% while maintaining the smoothing performance for SBS. We have also shown that the resulting coherence time of the laser has no effect on the maximum level of SBS achieved. Similarly, the impact of these developments on other instabilities such as stimulated Raman scattering or crossed beam energy transfer will also need to be investigated.

Λαμβάνοντας υπόψη, ότι η αποδοτική σχεδίαση, αξιολόγηση και εγκατάσταση ενός ασύρματου δικτύου επικοινωνιών, απαιτούν τον ακριβή χαρακτηρισμό του καναλιού διάδοσης και ειδικότερα των διαλείψεων μικρής και μεγάλης κλίμακας, το αντικείμενο μελέτης της παρούσας Διδακτορικής Διατριβής (ΔΔ) εστιάζεται στη μοντελοποίηση των διαλείψεων με νέα γενικότερα στατιστικά μοντέλα και απαρτίζεται από τρεις θεματικές ενότητες που αφορούν α) μοντέλα παρουσία συνιστώσας Οπτικής Επαφής (ΟΕ), β) μοντέλα που χαρακτηρίζονται από απουσία συνιστώσας ΟΕ καθώς και γ) χρήσιμες στατιστικές εκφράσεις για τη περιγραφή του τυχαίου θορύβου FM και της μέσης χωρητικότητας του καναλιού για μερικά από τα νέα κανάλια (α-μ, α-η-μ, α-κ-μ και α-λ-η-μ). Με βάση την υφιστάμενη διεθνή βιβλιογραφία, οι κατανομές που περιγράφουν κανάλια διαλείψεων δεν είναι αρκετά ευέλικτες και πολλές φορές είναι ανεπαρκείς για τη προσαρμογή αυτών σε δεδομένα προερχόμενα από πειραματικές μετρήσεις της έντασης ανά μονάδα επιφάνειας του ηλεκτρομαγνητικού πεδίου, τόσο για κανάλια εσωτερικών, όσο και για κανάλια υπαίθριων (εξωτερικών) χώρων. Έτσι, αρχικά δίδεται ο φυσικός μηχανισμός για την ερμηνεία κάθε νέου παρουσιαζόμενου μοντέλου. Χρησιμοποιώντας το μαθηματικό φορμαλισμό που προκύπτει από την μοντελοποίηση του ασύρματου καναλιού μέσω διαφόρων μιγαδικών Gaussian διεργασιών με διαφορετικές ιδιότητες, παρέχονται χρήσιμες εκφράσεις για την περιγραφή και αξιολόγηση των ψηφιακών συστημάτων επικοινωνιών που λειτουργούν σε περιβάλλοντα διαλείψεων. Στη συνέχεια, παρουσιάζεται η μελέτη που αφορά μοντέλα που υποθέτουν ότι η συνιστώσα πολυδιόδευσης συνυπάρχει με συνιστώσα. Έπειτα, πραγματοποιείται μελέτη μοντέλων που λειτουργούν σε συνθήκες διαλείψεων, όπου δεν υφίσταται συνιστώσα ΟΕ. Στη συνέχεια της ΔΔ, αναφορικά με κάποια από τα μοντέλα που παρουσιάστηκαν, πραγματοποιείται μελέτη και διερεύνηση του τυχαίου θορύβου FM και της Μέσης Χωρητικότητας του Καναλιού (ΜΧΚ). / The effective design, assessment, and installation of a wireless radio network require an accurate characterization of the propagation channel and, in particular, the small and large scale fading. By taking this into consideration, the subject of this Philosophy Diploma (PhD) dissertation is summarized in the characterization of fading with new more general statistical models and it is composed from three thematic units that concern: a) models under LOS conditions, v) models that are characterized by lack of a LOS component as well as c) useful statistical expressions for the description of random noise FM and average channel capacity for some of the new channels. A important amount of scientific work shows that the existing distributions are not enough flexible and many times are insufficient for the adaptation in data coming from experimental measurements of intensity per unit of surface of the electromagnetic field for both indoor and outdoor channels. Based on this fact, the objective of the Thesis was the production of new more general models with always natural background. Thus, initially, the natural mechanism is given for the interpretation of each new presented model. Using the mathematic formalism that results from the modelling of wireless channel via various complex Gaussian processes with different attributes, useful expressions are provided for the description and evaluation of digital communication systems that operate in fading environments. Consequently, initially, the basic theoretical background is presented that is rendered useful and essential for the study of fading channels. Next, a study is presented that concerns models that assume that the mulitpath part coexists with a LOS component. Then, a study of models, which assume NLOS conditions, takes place. In the next part of the PhD, in regard to some of the presented models, a study of random noise FM and ACC takes place.