Les activités humaines ont, depuis plus d'une centaine d'années, influencé de plus en plus fortement les cycles géochimiques contrôlant les niveaux d'acidité et de disponibilité en azote dans la nature. Les dépôts acides et azotés conduisent à une modification des conditions du milieu et notamment à des changements sensibles de la composition des communautés d'espèces végétales. L'objectif de cette thèse est de retracer l'évolution spatio-temporelle de l'acidité et de la disponibilité en azote des sols forestiers français au cours du 20ème siècle à partir du caractère bio-indicateur de la flore, à l'échelle locale ainsi globale. L'utilisation de la flore comme bio-indicateur vise à pallier l'absence de données de mesures directes des conditions édaphiques et des dépôts atmosphériques acides et azotés couvrant une large emprise spatio-temporelle. Premièrement, les variations de pH (indicateur d'acidité) et C:N (indicateur de disponibilité en azote) bio-indiquées ont été calculées à partir d'environ 100 000 relevés floristiques temporaires réalisés dans toute la France de 1910 à 2010. Elles ont été analysées par une méthode novatrice de comparaison spatio-temporelle, en différenciant les zones forestières sur substrat acide et non-acide ainsi que les forêts de conifères et de feuillus. Dans un second temps, nous avons analysé les changements des conditions édaphiques entre 1972 et 2011 à l'échelle de la forêt de Villey-Le-Sec, et ceux de la flore qu'ils induisent en lien avec d'autres évolutions environnementales, toujours à partir du caractère bio-indicateur de la flore.À l'échelle globale, nous avons observé une acidification des forêts françaises en milieu acide (-0.34 unités du pH en moyenne) et milieu non-acide (-0.19 unités du pH en moyenne), respectivement, jusqu'en 1984 et 1997. Nous avons ensuite mis en évidence, pour la première fois à notre connaissance, un arrêt dans l'acidification des sols forestiers et même une diminution de l'acidité sur substrat non-acide ainsi que un décalage temporel entre l'acidification des zones acides et non-acides. Cette évolution apparaît tout à fait cohérente avec celle connue des dépôts atmosphériques acidifiants en France depuis le début du 20ème siècle. Spatialement, nous confirmons la tendance temporelle, montrons une évolution régionalisée de l'acidification principalement sur substrat non-acide et soulignons la grande variabilité spatiale des changements de pH des sols forestiers. Concernant l'évolution de la disponibilité en azote, nous observons une diminution non attendue de celle-ci jusqu'en 1984 et 1997, respectivement, dans les forêts de conifères (+0.79 unités de C:N en moyenne) et de feuillus (+0.74 unités de C:N en moyenne). Une tendance à l'eutrophisation des sols forestiers a ensuite été observée dans les forêts de conifères et de feuillus à partir de 1997 (-0.10 et -0.16 unités de C:N en moyenne, respectivement). Cette évolution apparaît décalée par rapport à celle des dépôts azotés en France. [...] Suite et fin du résumé dans la thèse. / Human activities have, over the last century, strongly influenced the cycles controlling the levels of acidity and nitrogen availability in nature. Acidifying and eutrophying deposition lead to a change in environmental conditions and particularly to sensitive changes in plant communities' composition.The objective of this Ph.D work is to reconstruct the spatiotemporal evolution of the acidity and nitrogen availability in French forest soils over the 20th century using the bioindicator character of plants, into local and global scales. The use of plants as bioindicator seeks to mitigate the lack of direct measurements of soil conditions and atmospheric deposition, over a wide spatiotemporal extent. First, changes in bioindicated soil pH (indicator of acidity conditions) and C:N (indicator of nitrogen availability status) were computed from approximately 100 000 temporary floristic plots carried out throughout France from 1910 to 2010. They were analyzed using an innovative method of spatiotemporal comparison, where acidic and nonacidic forest areas and coniferous and broadleaved forests were differentiated. Secondly, and always from the bioindicator character of plants, changes in soil conditions between 1972 and 2011 across Villey forest as well as floristic changes they induce related with other environmental changes were analyzed.At the global level, we observed acidification in acidic forest areas (-0.34 pH units on average) and in nonacidic areas (-0.19 pH units on average), respectively, until 1984 and 1997. We demonstrated for the first time (to our knowledge) a cessation of acidification of forest soils and even a decrease in acidity in nonacidic forest areas, as wella as a time lag for acidification between acidic and nonacidic areas. This trend is consistent with the trend of acidifying deposition in France since the early 20th century. Spatially, our results confirm the temporal trends, show a regional geographic pattern of acidification (mainly observed in nonacidic areas), and highlight the high spatial variability of soil pH changes. Concerning the evolution of nitrogen availability conditions, we observed an unexpected decrease in available nitrogen until 1984 and 1997, respectively, in coniferous (+0.79 C:N units on average) and broadleaved forests (+0.74 C:N units on average). A trend to eutrophisation of forest soils was then observed in coniferous and broadleaved forests since 1997 (-0.10 and -0.16 C:N units on average, respectively). This trend is not consistent with the trend of nitrogen atmospheric deposition in France. ”Last and final summary in the thesis.”

L’isolation par rideaux d’air, avant d’être un confort, est actuellement un enjeu énergétique majeur. Malgré toutes les évolutions dans ce domaine, la nature du régime de l’écoulement du rideau d’air reste un facteur très influant sur les performances et la qualité de l’isolation. Il est impératif de trouver comment le stabiliser et éviter ou éloigner la région de la turbulence. Dans ce contexte, on a mis en oeuvre un ensemble d’outils de traitements d’images spécifiques aux textures présentes dans les images du jet rond basé sur des techniques de rehaussement d’images issues des méthodes d’interpolation. Plusieurs analyses de séquences d’images avec suivi spatio-temporel ont été effectuées en vue de prédire le passage à la turbulence. Une modélisation géométrique originale a été développée pour une meilleure compréhension du mouvement 3D du jet rond / Before being a comfort, the air curtain insulation is currently a major energy issue. Despite all the developments in this field, the nature of the air curtain flow regime remains a very influential factor on the performance and quality of insulation. It is imperative to find ways to stabilize it and to prevent the turbulence zone. In this context, we have implemented a set of specific processing tools for image textures present in the round jet images. Several analysis of image sequences with spatio-temporal monitoring were performed to predict the transition to turbulence. Original geometric modeling has been developed for better understanding of the 3D motion of the round jet

Durant cette thèse, nous abordons le problème de la fouille exhaustive de motifs pour un cas particulier de graphes : les grilles. Ces grilles peuvent être utilisées pour modéliser des objets ayant une structure régulière. Ces structures sont naturellement présentes dans de nombreux jeux de plateaux (les dames, les échecs ou le go par exemple) ou encore dans les modélisations d’écosystèmes utilisant des automates cellulaires. On les retrouve également à un plus bas niveau dans les images, qui sont des grilles 2D de pixels ou encore les vidéos, qui sont des grilles spatio-temporelles 2D+t de pixels. Au cours de cette thèse, nous avons proposé un nouvel algorithme de fouille de motifs fréquents dédié aux grilles spatio-temporelles, GriMA. L’usage des grilles régulières permet à notre algorithme de réduire la complexité des tests d’isomorphismes. Ces tests sont souvent utilisés par les algorithmes génériques de fouilles de graphes mais ayant une complexité importante, cela limite leur usage sur des données réelles. Deux applications ont été proposées pour évaluer notre algorithme : la classification d’images pour la fouille de grilles 2D et la prédiction d’automates cellulaires pour la fouille de grilles 2D+t. / During this thesis, we consider the exhaustive graph mining problem for a special kind of graphs : the grids. Theses grids can be used to model objects that present a regular structure. These structures are naturally present in multiple board games (checkers, chess or go for instance) or in ecosystems models using cellular automata. It is also possible to find this structure in a lower level in images, which are 2D grids of pixels, or even in videos, which are 2D+t spatio-temporal grids of pixels. In this thesis, we proposed a new algorithm to find frequent patterns dedicated to spatio-temporal grids, GriMA. Use of regular grids allow our algorithm to reduce the complexity of the isomorphisms test. These tests are often use by generic graph mining algorithm but because of their complexity, they are rarely used on real data. Two applications were proposed to evaluate our algorithm: image classification for 2D grids mining and prediction of cellular automata for 2D+t grids mining.

Nas últimas décadas, testemunhou-se um crescente interesse no estudo de sistemas complexos. Tais sistemas são compostos por pelo menos dois componentes fundamentais: elementos dinâmicos individuais e uma estrutura de organização definindo a forma de interação entre estes. Devido a dinâmica de cada elemento e a complexidade de acoplamento, uma grande variedade de fenômenos espaço-temporais podem ser observados. Esta tese tem como objetivo principal explorar o uso da dinâmica espaço-temporal em redes visando a solução de alguns problemas computacionais. Com relação aos mecanismos dinâmicos, a sincronização entre osciladores acoplados, a caminhada aleatória-determinística e a competição entre elementos na rede foram considerados. Referente à parte estrutural da rede, tanto estruturas regulares baseadas em reticulados quanto redes com estruturas mais gerais, denominadas redes complexas, foram abordadas. Este estudo é concretizado com o desenvolvimento de modelos aplicados a dois domínios específicos. O primeiro refere-se à utilização de redes de osciladores acoplados para construção de modelos de atenção visual. Dentre as principais características desses modelos estão: a seleção baseada em objetos, a utilização da sincronização/ dessincronização entre osciladores neurais como forma de organização perceptual, a competição entre objetos para aquisição da atenção. Além disso, ao comparar com outros modelos de seleção de objetos baseados em redes osciladores, um número maior de atributos visuais é utilizado para definir a saliência dos objetos. O segundo domínio está relacionado ao desenvolvimento de modelos para detecção de comunidades em redes complexas. Os dois modelos desenvolvidos, um baseado em competição de partículas e outro baseado em sincronização de osciladores, apresentam alta precisão de detecção e ao mesmo tempo uma baixa complexidade computacional. Além disso, o modelo baseado em competição de partículas não só oferece uma nova técnica de detecção de comunidades, mas também apresenta uma abordagem alternativa para realização de aprendizado competitivo. Os estudos realizados nesta tese mostram que a abordagem unificada de dinâmica e estrutura é uma ferramenta promissora para resolver diversos problemas computacionais / In the last decades, an increasing interest in complex system study has been witnessed. Such systems have at least two integrated fundamental components: individual dynamical elements and an organizational structure which defines the form of interaction among those elements. Due to the dynamics of each element and the coupling complexity, various spatial-temporal phenomena can be observed. The main objective of this thesis is to explore spatial-temporal dynamics in networks for solving some computational problems. Regarding the dynamical mechanisms, the synchronization among coupled oscillators, deterministic-random walk and competition between dynamical elements are taken into consideration. Referring to the organizational structure, both regular network based on lattice and more general network, called complex networks, are studied. The study of coupled dynamical elements is concretized by developing computational models applied to two specific domains. The first refers to the using of coupled neural oscillators for visual attention. The main features of the developed models in this thesis are: object-based visual selection, realization of visual perceptual organization by using synchronization / desynchronization among neural oscillators, competition among objects to achieve attention. Moreover, in comparison to other object-based selection models, more visual attributes are employed to define salience of objects. The second domain is related to the development of computational models applied to community detection in complex networks. Two developed models, one based on particle competition and another based on synchronization of Integrate-Fire oscillators, present high detection rate and at the same time low computational complexity. Moreover, the model based on particle competition not only offers a new community detection technique, but also presents an alternative way to realize artificial competitive learning. The study realized in this thesis shows that the unified scheme of dynamics and structure is a powerful tool to solve various computational problems

Made available in DSpace on 2016-08-10T11:06:59Z (GMT). No. of bitstreams: 1 LUCILELIA LEMES DE CASTRO SILVA NASCIMENTO.pdf: 1559212 bytes, checksum: f28a9b74e30c324bec433f840c7af921 (MD5) Previous issue date: 2014-04-11 / This study investigates a range of poetic works created with and disseminated through digital computer media, for their visual, kinetic, and textual practices. We seek to articulate an analytic method grounded in close readings of selected poems out of several contemporary subgenres chosen to focus on poetic practices that raise questions about spatiality, temporality, kineticism, and word-and-image construction. Our chief interest lies in the systematization of the management procedures to access cyber poetry as a poetic form that emerges and is orchestrated in digital media and the forms of engagement presented to the reader. We focus the study on three clusters of poems, the poetic events, the cinematographic poems and visual noise poems. In this study, the attention to the material is applied on the analyzed digital poems. We base on the N. Katherine Hayles s analysis of media. In studying the selected digital poems, we highlighted their spatiotemporal properties and the kinetic and word-picture constructions. We dealt with Flash and animated Poems in the visual noise poetry. We argue that the reader/user s active embodied engagement that is required in the poems analyzed in chapter two and the denial of an active participation in the poems of chapter three is part of the materiality of the works. We emphasize that digital poetry is in a field that is expanding and changing, we dare to say that the poetic writing exploration and experimentation in the age of new media has just begun. / Este estudo investiga uma série de obras poéticas criadas e divulgadas através das mídias digitais, por meio de suas práticas visuais, cinéticas e textuais. Procuramos articular um método analítico fundamentado em leituras de poemas selecionados em vários subgêneros contemporâneos escolhidos para se concentrarem em práticas poéticas que levantem questões sobre a espacialidade, a temporalidade, o cinetismo e a construção de palavras e imagens. O nosso foco principal reside na sistematização dos procedimentos de manejo para acesso à ciberpoesia como forma poética que emerge e é orquestrada em mídias digitais e as formas de engajamento que são apresentadas ao leitor. Concentramos o estudo em três grupos de poemas: os Eventos Poéticos, Poemas Cinematográficos e os Poemas de Ruído Visual. Neste estudo, a atenção ao material é exercida sobre os poemas digitais analisados. Baseamo-nos na análise de mídia de N. Katherine Hayles. Ao estudarmos os poemas digitais selecionados, destacamos as suas propriedades espaço-temporais, as construções cinéticas de palavra-eimagem. Tratamos de poemas em Flash e poemas animados na poesia de ruído visual. Defendemos que o engajamento ativo incorporado que é exigido do leitor/usuário nos poemas analisados no capítulo dois e a negação de uma participação ativa nos poemas do capítulo três faz parte da materialidade das obras. Ressaltamos que a poesia digital constitui-se em um campo que está se expandindo e mudando, não seria ousadia afirmar que a exploração e a experimentação da escrita poética na era das novas mídias apenas começaram.

Informações que caracterizam o risco quebra de produção agrícola são necessárias para a precificação de prêmio do seguro agrícola de produção e de renda. A distribuição de probabilidade da variável rendimento agrícola é uma dessas informações, em especial aquela que descreve a variável aleatória rendimento agrícola condicionada aos fatores de risco climáticos. Este trabalho objetiva aplicar redes Bayesianas (grafo acíclico direcionado, ou modelo hierárquico Bayesiano) a estimação da distribuição de probabilidade de rendimento da soja em alguns municípios do Paraná, com foco na analise comparativa de riscos. Dados meteorológicos (ANA e INMET, período de 1970 a 2011) e de sensoriamento remoto (MODIS, período de 2000 a 2011) são usados conjuntamente para descrever espacialmente o risco climático de quebra de produção. Os dados de rendimento usados no estudo (COAMO, período de 2001 a 2011) requerem agrupamento de todos os dados ao nível municipal e, para tanto, a seleção de dados foi realizada nas dimensões espacial e temporal por meio de um mapa da cultura da soja (estimado por SVM - support vector machine) e os resultados de um algoritmo de identificação de ciclo de culturas. A interpolação requerida para os dados de temperatura utilizou uma componente de tendência estimada por dados de sensoriamento remoto, para descrever variações espaciais da variável que são ofuscadas pelos métodos tradicionais de interpolação. Como resultados, identificou-se relação significativa entre a temperatura observada por estações meteorológicas e os dados de sensoriamento remoto, apoiando seu uso conjunto nas estimativas. O classificador que estima o mapa da cultura da soja apresenta sobre-ajuste para safras das quais as amostras usadas no treinamento foram coletadas. Além da seleção de dados, a identificação de ciclo também permitiu obtenção de distribuições de datas de plantio da cultura da soja para o estado do Paraná. As redes bayesianas apresentam grande potencial e algumas vantagens quando aplicadas na modelagem de risco agrícola. A representação da distribuição de probabilidade por um grafo facilita o entendimento de problemas complexos, por suposições de causalidade, e facilita o ajuste, estruturação e aplicação do modelo probabilístico. A distribuição log-normal demonstrou-se a mais adequada para a modelagem das variáveis de ambiente (soma térmica, chuva acumulada e maior período sem chuva), e a distribuição beta para produtividade relativa e índices de estado (amplitude de NDVI e de EVI). No caso da regressão beta, o parâmetro de precisão também foi modelado com dependência das variáveis explicativas melhorando o ajuste da distribuição. O modelo probabilístico se demonstrou pouco representativo subestimando bastante as taxas de prêmio de seguro em relação a taxas praticadas no mercado, mas ainda assim apresenta contribui para o entendimento comparativo de situações de risco de quebra de produção da cultura da soja. / Information that characterize the risk of crop losses are necessary to crop and revenue insurance underwriting. The probability distribution of yield is one of this information. This research applies Bayesian networks (direct acyclic graph, or hierarchical Bayesian model) to estimate the probability distribution of soybean yield for some counties in Paraná state (Brazil) with focus on risk comparative analysis. Meteorological data (ANA and INMET, from 1970 to 2011) and remote sensing data (MODIS, from 2001 to 2011) were used to describe spatially the climate risk of production loss. The yield data used in this study (COAMO, from 2001 to 2011) required grouping to county level and, for that, a process of data selection was performed on spatial and temporal dimensions by a crop map (estimated by SVM - support vector machine) and by the results of a crop cycle identification algorithm. The interpolation required to spatialize temperature required a trend component which was estimated by remote sensing data, to describe the spatial variations of the variable obfuscated by traditional interpolation methods. As results, a significant relation between temperature from meteorological stations and remote sensing data was found, sustaining the use of the supposed relation between the two variables. The soybean map classifier shown over-fitting for the crop seasons for which the training samples were collected. Besides the data collection, a seeding dates distribution of soybean in Paraná state was obtained from the crop cycle identification process. The Bayesian networks showed big potential and some advantages when applied to agronomic risk modeling. The representation of the probability distribution by graphs helps the understanding of complex problems, with causality suppositions, and also helps the fitting, structuring and application of the probabilistic model. The log-normal probability distribution showed to be the best to model environment variables (thermal sum, accumulated precipitation and biggest period without rain), and the beta distribution to be the best to model relative yield and state indexes (NDVI and EVI ranges). In the case of beta regression, the precision parameter was also modeled with explanation variables as dependencies increasing the quality of the distribution fitting. In the overall, the probabilistic model had low representativity underestimating the premium rates, however it contributes to understand scenarios with risk of yield loss for the soybean crop.

Os efeitos de borda e a alteração da estrutura das paisagens constituem consequências negativas da fragmentação florestal responsáveis por transformações nos processos ecológicos. Decorrentes da expansão desordenada de atividades antrópicas, estas alterações podem comprometer o futuro dos remanescentes florestais e a manutenção dos recursos naturais na superfície terrestre. Nesta dissertação a dinâmica da vegetação arbórea foi analisada em oito transectos perpendiculares às bordas de seis remanescentes florestais entre 1996 e 2012. As paisagens do entorno destes transectos foram caracterizadas a partir de imagens orbitais de 1995 e 2011 para a verificação das mudanças ocorridas no uso do solo e para a investigação da influência de seus parâmetros físicos e estruturais sobre as taxas de mortalidade e recrutamento de espécies. Os resultados indicaram que, ao longo do tempo, a influência das bordas se pronunciou em direção ao interior dos remanescentes florestais, enquanto que o contraste entre a borda e o interior se atenuou. A distância média da borda das espécies: pioneiras/iniciais, anemocóricas e de dossel foi significativamente maior em 2012 do que em 1996. A comunidade arbórea apresentou menor similaridade em sua composição ao longo do tempo a menores distâncias da borda. Apesar da dinâmica verificada no uso do solo, a proporcionalidade dos parâmetros físicos e estruturais das paisagens se manteve entre 1995 e 2011. De maneira geral, estes parâmetros apresentaram pouca influência sobre a dinâmica da comunidade arbórea. Apenas as taxas de mortalidade das espécies exóticas e as taxas de recrutamento das espécies pioneiras/inicias apresentam forte relação com o tamanho e o número dos fragmentos florestais nas paisagens. Estes resultados indicam que os efeitos de borda precisam ser atenuados e que o contexto das paisagens deve ser incorporado às estratégias conservacionistas para que estas sejam efetivas e o futuro dos remanescentes florestais não seja comprometido. / Edge effects and landscape structure alterations are among the negative consequences of forest fragmentation responsible for ecological process alterations on the earths surface. Originated from the disordered expansion of anthropogenic activities these alterations may endanger the remaining forest patches future and the maintenance of natural resources. This dissertation was pledged to analyze the vegetation dynamics at forest edges and its relations with landscape features. The vegetation dynamics was examined through eight perpendicular-to-edge transects within six forest patches and the alterations on the arboreal community distribution and composition were assessed between 1996 and 2012. The surrounding landscapes of the analyzed transects were characterized from 1995 and 2011 orbital images and its land use changes were evaluated. Landscape structure and physical parameters influence were analyzed over species recruitment and mortality. The results indicated that the distance of edge influence increased over time while its magnitude was attenuated. The average distance from the edge of pioneer/earlysuccessional species, wind-dispersed and canopy species in 2012 became significantly larger than in 1996. Over time lower similarities in species composition were found to be closer to the edges. Although the observed land use changes in the surrounding landscapes of the edge transects landscape structure and physical parameters proportionality was maintained between 1995 and 2011. Overall the arboreal community dynamics were poorly associated with landscape features. A strong relation of the variables was only found between the exotic and pioneer/early-successional species mortality and recruitment and the size and the amount of forest patches within the landscapes. These results indicate that to be effective conservation planning must tackled edge effects and incorporate the landscape context otherwise they will fail for the maintenance of the future of forest patches.

Entre les fleuves Amazone et Orénoque, la frange côtière atlantique de l’Amérique du Sud (1500 km) est considérée comme la plus vaseuse au monde, conséquence des apports de sédiments en suspension de l’Amazone. Malgré la forte variabilité et l’instabilité de ces vasières uniques au monde, elles apparaissent comme des écosystèmes très productifs et sont des habitats clés dans l’accomplissement du cycle de vie des espèces de poissons et d’oiseaux qui les exploitent. Cependant, les connaissances sur les communautés biologiques qui y sont associées restent au niveau exploratoire. Ce travail de thèse vise donc à décrire la structure de l’endofaune benthique intertidale des vasières guyanaises et à définir son fonctionnement dans des environnements vaseux tropicaux très instables. Comme prévu, la forte instabilité des sédiments a entraîné une très faible diversité des assemblages de la macrofaune et de la méiofaune. Néanmoins, les communautés benthiques des vasières guyanaises ont montré une abondance remarquablement élevée avec la dominance d'espèces opportunistes de petites tailles. 39 taxons de la macrofaune ont été trouvés tandis que la méiofaune était moins diversifiée avec la présence de 34 taxons. Le tanaidacée Halmyrapseudes spaansi et le polychète Sigambra grubii sont les deux espèces de macrofaune les plus abondantes, largement réparties le long de la côte guyanaise. De même, le nématode Pseudochromadora spp., suceur d’épistrate, et Halomonhystera sp. 1 (non deposit feeders) étaient les deux espèces de méiofaune les plus abondantes sur chacune des stations. La distribution des communautés benthiques sont spécifiques aux sites d’étude et varie saisonnièrement. Les assemblages en zone estuarienne (Sinnamary) étaient plus diversifiées que dans la zone de vasière nue (Awala), alors que les abondances des communautés benthiques étaient toujours plus élevées en saison humide qu’en saison sèche. Les facteurs abiotiques et biotiques ont influencé significativement les communautés benthiques. Néanmoins, les changements dans la structure de la communauté benthique induits par la disponibilité des sources alimentaires (chl a) et la pression de prédation étaient tout aussi importantes que les variations des assemblages imposées par les paramètres abiotiques (teneur en eau, salinité ...). En particulier, une forte corrélation a été trouvée entre la méiofaune et le microphytobenthos. Les mesures isotopiques de différents compartiments des vasières ont non seulement révélé le rôle central du microphytobenthos dans la composition du régime alimentaire de la méiofaune, mais ont également montré l'importance écologique de la méiofaune comme principale source de nourriture pour les petits oiseaux limicoles et les poissons côtiers. La méiofaune et le microphytobenthos rentrent dans le régime alimentaire de trois poissons côtiers en grande proportion, alors que les oiseaux limicoles migrateurs présentaient une plus grande diversité de proies. Cependant, la contribution relative des tanaidacées dans le régime alimentaire des oiseaux limicoles était étonnamment faible. Le travail de thèse a permis d'améliorer notre compréhension de la structure de l’endofaune benthique intertidale des vasières guyanaises et de définir son fonctionnement dans des environnements vaseux tropicaux très instables. Ce travail a permis de construire, pour la première fois, un modèle conceptuel de réseau trophique des vasières intertidales mobiles guyanaises. / Locating between the Amazon and Orinoco Rivers, the 1500 km-long Atlantic coastline of South America are considered as the muddiest areas in the world due to the large discharge of suspended sediment from the Amazon. Despite the extreme morphodynamics of these ecosystems, the Guianas mudflats are important feeding zones for many shorebirds and fish. However, the state of knowledge on benthic organisms associated with these highly unstable environments is still at an exploratory stage. This study, therefore, aims to describe the structure and dynamics of the intertidal benthic infauna in the Guianas mudflats and to define its functioning in such highly unstable tropical muddy environments. As expected, the high instability of the sediment resulted in very low diversity of both macrofauna and meiofauna assemblages. Nonetheless, the infauna communities of the Guianas mudflats showed remarkably high abundance with the predominance of small-sized opportunistic species. A total of 39 operational taxonomic units of macrofauna was recorded while meiofauna was less diverse with the occurrence of 34 taxa. The tanaid Halmyrapseudes spaansi and the polychaeta Sigambra grubii are the two most abundant macrofauna species, which widely distributed along the Guianas coast. Likewise, the nematodes epistrate feeder Pseudochromadora spp. and non-deposit feeders Halomonhystera sp. 1 were the principal components of meiofauna communities in every station. The distribution patterns of the infauna were both site-specific and seasonal variation. The assemblages in estuarine habitat were more diverse than in the bare mudflat habitat, while infauna abundances in the WS were always higher than in the DS. Both abiotic and biotic factors significantly influenced the benthic communities. Nevertheless, the changes in benthic community structure induced by food source availability (chl a) and predation pressure were more prominent than the assemblage variations imposed by abiotic parameters (mud content, salinity…). Particularly, the tight coupling between meiofauna and MPB was observed in both distribution patterns and trophic structures. The isotopic measurements of different intertidal compartments not only revealed the pivotal role of MPB on structuring meiofaunal coummunities, but also indicated the ecological importance of meiofauna as the main food source for the small shorebirds and coastal fish. Meiofauna and MPB entered the diet of three coastal fish in great proportion, whereas the migrating shorebirds showed a wider diet breadth. The isotopic ratios were perfectly matched with the feeding guilds assigned by morphological features. However, the relative contribution of tanaids to the top epibenthic predators were surprisingly lower than expected. The thesis has increased our understanding of the Guianas infauna communities, and revealed for the first time a conceptual food web model of these unique intertidal mudflats.

In this thesis, the basic tools of spatial statistics and time series analysis are applied to the case study of the earthquakes in a certain geographical region and time frame. Then some of the existing methods for joint analysis of time and space are described and applied. Finally, additional research questions about the spatial-temporal distribution of the earthquakes are posed and explored using statistical plots and models. The focus in the last section is in the relationship between number of events per year and maximum magnitude and its effect on how clustered the spatial distribution is and the relationship between distances in time and space in between consecutive events as well as the distribution of the distances.

La circulation routière est une source majeure de pollution atmosphérique dans les zones urbaines. Les décideurs insistent pour qu’on leur propose de nouvelles solutions, y compris de nouvelles stratégies de management qui pourraient directement faire baisser les émissions de polluants. Pour évaluer les performances de ces stratégies, le calcul des émissions de pollution devrait tenir compte de la dynamique spatiale et temporelle du trafic. L’utilisation de capteurs traditionnels sur route (par exemple, capteurs inductifs ou boucles de comptage) pour collecter des données en temps réel est nécessaire mais pas suffisante en raison de leur coût de mise en oeuvre très élevé. Le fait que de telles technologies, pour des raisons pratiques, ne fournissent que des informations locales est un inconvénient. Certaines méthodes devraient ensuite être appliquées pour étendre cette information locale à une grande échelle. Ces méthodes souffrent actuellement des limites suivantes : (i) la relation entre les données manquantes et la précision de l’estimation ne peut être facilement déterminée et (ii) les calculs à grande échelle sont énormément coûteux, principalement lorsque les phénomènes de congestion sont considérés. Compte tenu d’une simulation microscopique du trafic couplée à un modèle d’émission, une approche innovante de ce problème est mise en oeuvre. Elle consiste à appliquer des techniques de sélection statistique qui permettent d’identifier les emplacements les plus pertinents pour estimer les émissions des véhicules du réseau à différentes échelles spatiales et temporelles. Ce travail explore l’utilisation de méthodes statistiques intelligentes et naïves, comme outil pour sélectionner l’information la plus pertinente sur le trafic et les émissions sur un réseau afin de déterminer les valeurs totales à plusieurs échelles. Ce travail met également en évidence quelques précautions à prendre en compte quand on calcul les émissions à large échelle à partir des données trafic et d’un modèle d’émission. L’utilisation des facteurs d’émission COPERT IV à différentes échelles spatio-temporelles induit un biais en fonction des conditions de circulation par rapport à l’échelle d’origine (cycles de conduite). Ce biais observé sur nos simulations a été quantifié en fonction des indicateurs de trafic (vitesse moyenne). Il a également été démontré qu’il avait une double origine : la convexité des fonctions d’émission et la covariance des variables de trafic. / Road traffic is a major source of air pollution in urban areas. Policy makers are pushing for different solutions including new traffic management strategies that can directly lower pollutants emissions. To assess the performances of such strategies, the calculation of pollution emission should consider spatial and temporal dynamic of the traffic. The use of traditional on-road sensors (e.g. inductive sensors) for collecting real-time data is necessary but not sufficient because of their expensive cost of implementation. It is also a disadvantage that such technologies, for practical reasons, only provide local information. Some methods should then be applied to expand this local information to large spatial extent. These methods currently suffer from the following limitations: (i) the relationship between missing data and the estimation accuracy, both cannot be easily determined and (ii) the calculations on large area is computationally expensive in particular when time evolution is considered. Given a dynamic traffic simulation coupled with an emission model, a novel approach to this problem is taken by applying selection techniques that can identify the most relevant locations to estimate the network vehicle emissions in various spatial and temporal scales. This work explores the use of different statistical methods both naïve and smart, as tools for selecting the most relevant traffic and emission information on a network to determine the total values at any scale. This work also highlights some cautions when such traffic-emission coupled method is used to quantify emissions due the traffic. Using the COPERT IV emission functions at various spatial-temporal scales induces a bias depending on traffic conditions, in comparison to the original scale (driving cycles). This bias observed in our simulations, has been quantified in function of traffic indicators (mean speed). It also has been demonstrated to have a double origin: the emission functions’ convexity and the traffic variables covariance.