Identification du bâti à partir d'images satellitaires à très hautes résolutions spatiales

Résumé: L'urbanisation est un phénomène croissant qui touche l'ensemble du globe et qui a comme conséquence l'étalement des surfaces urbanisées. L'ampleur et la rapidité de cet étalement posent partout des problèmes socio-économiques et environnementaux. Pour réduire au maximum ces problèmes, les aménageurs ont besoin de données spatiales à intégrer aux outils de gestion et de planification. Dans ce contexte général, l'apparition des images satellitaires à Très Haute Résolution Spatiale (THRS) suscitent de fortes attentes. Ces images conjuguent en effet des résolutions spatiales fines, à des coûts raisonnables d'acquisition et à des courtes périodes de revisites. Les méthodes d'interprétation actuelles apparaissent cependant inadaptées à ces nouvelles images. À partir de cette problématique, l'objectif de notre recherche est identifié comme l'élaboration d'une méthode d'extraction semi-automatique des bâtiments à partir d'images THRS. Pour atteindre cet objectif, nous avons déterminé plusieurs étapes. Chacune d'elles est associée à un chapitre de cette thèse. Le premier chapitre expose le contexte général de notre recherche et conduit à l'identification de notre objectif. Nous présentons tout d'abord un bref historique de l'urbanisation avant de nous concentrer sur le phénomène d'étalement et sur les problèmes qu'il engendre. Nous nous intéressons ensuite à ce que la géographie peut apporter pour diminuer ces problèmes. Les positionnements conceptuels, théoriques et méthodologiques de l'analyse géographique des villes sont suivis d'une présentation des principaux outils de gestion et de planification urbaine. Il ressort un besoin croissant en données spatiales à intégrer à ces outils, besoin à partir duquel nous identifions notre objectif. Dans le second chapitre, nous vérifions la faisabilité de notre objectif à travers l'analyse des caractéristiques techniques des images puis des perturbations subies par le signal. La capacité des images à représenter fidèlement les objets urbains est ensuite abordée à travers les notions de qualité et d'interprétabilité des images. Les résultats confirment l'intérêt de l'utilisation des images satellitaires THRS pour l'analyse des objets urbains. Le troisième chapitre présente les phases préliminaires à l'élaboration de notre méthode d'extraction des bâtiments. Nous évaluons tout d'abord la qualité (géométrique et radiométrique) de l'image Ikonos support d'étude. Une revue des méthodes existantes fait ensuite ressortir une limite commune : la délimitation précise des bâtiments. Ce constat nous conduit à évaluer la qualité des méthodes de segmentation puis à réorienter nos choix méthodologiques. Le quatrième chapitre présente ce qui constitue le coeur de notre travail, à savoir le développement d'une méthode d'extraction du bâti. Après une formalisation rigoureuse des objectifs, nous présentons les principes théoriques de notre approche qui s'appuie sur une définition texturale des bâtiments. Le processus d'identification est basé sur la prise en compte conjointe, à l'aide d'un paramètre unique, de la variance du bâtiment et de celle de son entourage proche. Des informations additionnelles (présence d'ombre et de végétation) sont ensuite intégrées dans le but de diminuer les erreurs de commission. Le cinquième chapitre présente les résultats. Il montre la capacité de la méthode à identifier les bâtiments malgré certaines limites d'applicabilité, en particulier dans le cas des grands bâtiments et/ou dans les milieux hétérogènes. Des pistes d'améliorations sont proposées ainsi que des perspectives d'applications. Il ressort de ce travail que le principal apport tient dans l'originalité de l'approche théorique qui ouvre de nouvelles pistes de réflexion pour les travaux futurs.||Abstract: Urbanisation still remains one of the main problems worldwide. The extent and rapidity of the urban growth induce a number of socio-economic and environmental conflicts everywhere. In order to reduce these problems, urban planners need to integrate spatial information in planning tools. Actually high expectations are made on Very High Spatial Resolution imagery (VHSR). These high-spatial resolution images are available at a reasonable price and due to short revisit periods, they offer a high degree of actuality. However, interpretation methods seem not to be adapted to this new type of images. The aim of our study is to develop a new method for semi-automatic building extraction with VHSR. The different steps performed to achieve our objective are each presented in a chapter. In the first chapter, the general context of our research is described with the definition of our objective. After a short historical review of urbanisation, we focus on urban growth and associated problems. In the following we discuss the possible contributions of geography to reduce these problems. After discussing concepts, theories and methodologies of geographical analysis in urban areas, we present existing general urban planning tools. Finally, we show the special interest of our study that is due to a growing need to integrate spatial information in these decision support tools. In the second chapter we verify the possibility of reaching our objective by analysing the technical characteristics of the images, the noise and the distortions which affect the images. Quality and interpretability of the studied image is analysed in order to show the capacity of these image to represent urban objects as close to reality as possible. The results confirm the potential of VHSR Imagery for urban objects analysis. The third chapter deal with the preliminary steps necessary for the elaboration of our method of building extraction. First, we evaluate the quality of the Sherbrooke Ikonos image (geometric and radiometric quality), the basic image of our analysis. A review of existing methods clearly show a common limit: the detection of building boundaries. Consequently, we evaluate the efficiency of several segmentation methods that finally induces a change in our methodological approach. The fourth chapter contains the central part of our work, which consists in the development of a building extraction method. After strict formalisation of our, objectives, we present the theoretical principles of our approach based on textural buildings definition. In the identification process we use only one parameter that accounts at the same time for the variance of the building and the variance of its immediate surroundings. In the following, additional information (shadow and vegetation) is integrated to reduce commission errors. The last chapter exposes the results. They clearly show the capacity of our method for building identification. However, they show some limitations of application, especially on large size buildings and/or in heterogeneous areas. We also propose possible applications such as analysis of suburban buildings or detection of natural disaster damages. The main outcome of this work is the originality of our theoretical approach that encourages new reflections for future research

A polyphasic approach to study the dynamics of microbial population of an organic wheat sourdough during its conversion to gluten-free sourdough

To develop a method for organic gluten-free (GF) sourdough bread production, a long-term and original wheat sourdough was refreshed with GF flours. The dynamics of the sourdough microbiota during five months of back-slopping were analyzed by classical enumeration and molecular methods, including PCR-temporal temperature gel electrophoresis (PCR-TTGE), multiplex PCR, and pulsed field gel electrophoresis (PFGE). The results showed that the yeast counts remained constant, although Saccharomyces cerevisiae, present in the initial wheat sourdough, was no longer detected in the GF sourdough, while lactic acid bacteria (LAB) counts increased consistently. In the first phase, which was aimed at obtaining a GF sourdough from wheat sourdough, Lactobacillus sanfranciscensis, L. plantarum, and L. spicheri were the main LAB species detected. During the second phase, aimed at maintaining the GF sourdough, the L. plantarum and L. spicheri populations decreased whereas L. sanfranciscensis persisted and L. sakei became the predominant species. Multiplex PCRs also revealed the presence of several L. sakei strains in the GF sourdough. In a search for the origin of the LAB species, PCR-TTGE was performed on the flour samples but only L. sanfranciscensis was detected, suggesting a flour origin for this typical sourdough species. Thus, while replacement of the wheat flour by GF flour influenced the sourdough microbiota, some of the original sourdough LAB and yeast species remained in the GF sourdough. [Int Microbiol 2014; 17(1):1-9]Keywords: Lactobacillus spp. · Saccharomyces · Candida ·  sourdough · gluten-free food · organic · lactic acid bacteria · yeas

Inflammatory cells dynamics control neovascularization and tissue healing after localized radiation induced injury in mice

Abstract Local overexposure to ionizing radiation leads to chronic inflammation, vascular damage and cachexia. Here we investigate the kinetics of inflammatory cells from day (D)1 to D180 after mouse hindlimb irradiation and analyze the role of monocyte (Mo) subsets in tissue revascularization. At D1, we find that Mo and T cells are mobilized from spleen and bone marrow to the blood. New vessel formation during early phase, as demonstrated by ~1.4- and 2-fold increased angiographic score and capillary density, respectively, correlates with an increase of circulating T cells, and Mohi and type 1-like macrophages in irradiated muscle. At D90 vascular rarefaction and cachexia are observed, associated with decreased numbers of circulating Molo and Type 2-like macrophages in irradiated tissue. Moreover, CCR2- and CX3CR1-deficency negatively influences neovascularization. However adoptive transfer of Mohi enhances vessel growth. Our data demonstrate the radiation-induced dynamic inflammatory waves and the major role of inflammatory cells in neovascularization

Hepatitis E Virus Strains in Rabbits and Evidence of a Closely Related Strain in Humans, France

Hepatitis E virus (HEV) strains from rabbits indicate that these mammals may be a reservoir for HEVs that cause infection in humans. To determine HEV prevalence in rabbits and the strains’ genetic characteristics, we tested bile, liver, and additional samples from farmed and wild rabbits in France. We detected HEV RNA in 7% (14/200) of bile samples from farmed rabbits (in 2009) and in 23% (47/205) of liver samples from wild rabbits (in 2007–2010). Full-length genomic sequences indicated that all rabbit strains belonged to the same clade (nucleotide sequences 72.2%–78.2% identical to HEV genotypes 1–4). Comparison with HEV sequences of human strains and reference sequences identified a human strain closely related to rabbit strain HEV. We found a 93-nt insertion in the X domain of open reading frame 1 of the human strain and all rabbit HEV strains. These findings indicate that the host range of HEV in Europe is expanding and that zoonotic transmission of HEV from rabbits is possible

Risk of zoonotic transmission of HEV from rabbits

International audienceHepatitis E virus strains from rabbits indicate that these mammals may be a reservoir for HEVs that cause infection in humans. Further issues remain to be clarified, including whether the genotype of rabbit HEV differs from human and swine HEV genotype 3 and whether rabbit HEV can infect human and other animals. HEV was found in farmed rabbits in several geographic areas of China, in USA and more recently in France. The prevalence of antibodies against HEV was 36%, 57% and 55% in rabbits from Virginia (USA), Gansu Province and Beijing (China), respectively. HEV RNA was detected in 16.5% of serum samples from farmed rabbits in Virginia, 7.5% in Gansu Province and 7.0% in Beijing. HEV RNA was detected in 7% of bile samples from farmed rabbits and in 23% of liver samples from wild rabbits in France. The full-length genomic sequences analysis indicates that all the rabbit strains belong to the same clade. Nucleotide sequences were 72.2-78.2% identical to HEV genotypes 1-4. Comparison with HEV sequences of human strains circulating in France and reference sequences identified a human strain closely related to rabbit HEV. A 93-nucleotide insertion in the X domain of the ORF1 of the human strain and in all the rabbit HEV strains was found. Moreover, the ability of rabbit HEV to cause cross-species infection in a pig model has recently been demonstrated. Rabbit HEV can replicate efficiently in human cell lines. Collectively, these data support the possibility of zoonotic transmission of HEV from rabbits. (C) 2013 Published by Elsevier B.V

Oligonucleotides-derivatized with luminescent and photoreactive Ru(II) complexes: models for photo-electron transfer and photocrosslinking

info:eu-repo/semantics/publishe

Ru-labeled oligonucleotides for photoinduced reactions on targeted DNA guanines

A series of 17-mer oligonucleotides labeled with [Ru(tap)2(dip)]2+ (tap = 1,4,5,8-tetraazaphenanthrene; dip = 4,7-diphenylphenanthroline) at position 5 of an uracil residue in the middle of the sequence (e.g. see scheme) have been prepared and characterized. The luminescence of the chemically attached complex is quenched by hybridization with the complementary sequence, when it contains guanines in the vicinity of the Ru site. This electron-transfer quenching process generates a photoproduct on the illuminated duplex, that is responsible for an irreversible photocrosslinking of the two strands.FLWINinfo:eu-repo/semantics/publishe