Centralités et territorialités artistiques dans la structuration des espaces urbains

La culture apparaît comme un élément de la définition du statut métropolitain d’une ville et comme un argument de distinction dans un contexte de compétition internationale entre les villes. La présence artistique dans les villes est souvent associée à des dynamiques de transformation et de revalorisation des espaces urbains. Cette thèse place au centre de l’analyse les espaces urbains de l'art contemporain dans deux métropoles artistiques majeures Paris et Berlin. Elle aborde de manière conj..

Centralités et territorialités artistiques dans la structuration des espaces urbains. Le cas de Paris et Berlin

Culture is considered as an important element defining metropolitan status as well as a distinguishing argument in the context of international and inter-urban competition. Within cities, artistic presence is frequently associated with the transformation and revaluation of urban spaces. Contemporary art - as a global object, locally produced - and its urban spaces are the core of this research, which explores the issues related to both the cultural visibility of a city as well as artistic presence. The spatial organisation of contemporary art spaces, in Paris and in Berlin, that was taken into account thanks to the construction of an original database, shows, beyond differences that are linked to particular historic and urban contexts, the importance of multipolarised urban systems, where artistic diffusion and creation contribute to the emergence of specialised centralities. The involvement of Paris and Berlin in artistic networks mirrors the interdependencies that are revealed by functional specialisations. The artistic exchanges that we consider through contemporary art exhibitions underline the global dimension of the artistic networks. They also show that the artistic systems in Paris and Berlin are structured by intra-metropolitan exchanges between spaces of creation and spaces of diffusion. The coexistence of strong endogenous dynamics and significant artistic exchanges at different scales underline the pivotal role played by Paris and Berlin, at the interface of multiple artistic networks. Spatial practices of artists are examined at the local scale of urban spaces of creation, in Montreuil, for the Parisian case and in Neukölln for Berlin. We show that they play an important role in the collective affirmation of a creative identity. They also underline the interactions and interdependencies that contribute to urban concentration of artistic creation. This research highlights, through a comparative and multiscalar approach, urban spaces of art whose dynamics contribute to reinforce metropolitan centralities as well as contributing to the emergence of artistic centralities. We pay particular attention to artistic circulation that increases the diversity of the metropolitan connections defining the position of both cities, as well as contributing to the emergence of transnational spaces within each city. This research, crossing case studies, approaches and scales, shows the role of art spaces in the urban production processes, contributing to the reinforcment of existing centralities, as well as the emergence of more speciific and specialised centralities.La culture apparaît comme un élément de la définition du statut métropolitain d'une ville et comme un argument de distinction dans un contexte de compétition internationale entre les villes. La présence artistique dans les villes est souvent associée à des dynamiques de transformations et de revalorisation des espaces urbains. Cette thèse place au centre de l'analyse les espaces urbains de l'art contemporain dans deux métropoles artistiques majeures Paris et Berlin. Elle aborde de manière conjointe des enjeux liés au rayonnement culturel des deux métropoles et à la présence artistique. L'organisation des espaces urbains de l'art à Paris et à Berlin, mise en évidence grâce à un recensement original des lieux de création et de diffusion artistiques, montre - malgré des différences qui tiennent à des histoires et des contextes urbains particuliers - l'existence de structures métropolitaines multipolaires caractérisées par des centralités spécialisées. Ces spécialisations tiennent d'une part à la nature même de l'activité artistique des lieux d'exposition et, d'autre part aux échanges artistiques observés au prisme des expositions d'art contemporain organisées à Paris et à Berlin et qui contribuent à souligner l'insertion de ces deux métropoles dans les réseaux artistiques globaux. Cette thèse donne donc à voir dans un premier temps des systèmes artistiques parisiens et berlinois où coexistent une dynamique d'échanges endogène forte et une animation de réseaux artistiques majeurs à différentes échelles soulignant ainsi le rôle de pivots de Paris et Berlin, à l'interface de réseaux artistiques locaux et globaux. Les pratiques spatiales des artistes sont interrogées à l'échelle locale d'espaces urbains marqués par la création, comme à Montreuil dans le cas parisien et à Neukölln dans le cas de Berlin. Cette thèse montre, dans un second temps, comment ces pratiques sont déterminantes à la fois dans la définition d'espaces de création et dans les processus à l'œuvre dans l'affirmation collective d'une identité créatrice. En portant une attention particulière aux circulations des artistes, cette thèse explicite également le fonctionnement de territoires transnationaux au sein des métropoles. À travers une approche qui croise les contextes urbains, les échelles d'analyse et les méthodes, cette thèse montre le rôle des espaces de l'art dans la fabrique de l'urbain, contribuant au renforcement des centralités métropolitaines existantes et aussi à l'émergence de centralités artistiques plus spécifiques et spécialisées

Evidence for a Cr metastable phase as a tracer in DLI-MOCVD chromium hard coatings usable in high temperature environment

Cr deposits are widely used as protective coatings but multifunctional performances are required in harsh environments motivating research on new processes. MOCVD of Cr metal coatings was carried out by direct liquid injection (DLI) of a unique solution containing bis(ethylbenzene)chromium as metal source and thiophenol as inhibitor of carbide formation. A low amount (<6%) of the metastable δ-Cr phase was found embedded in the stable α-Cr phase. The formation of this metastable phase originates from both the low deposition temperature (<723 K) and the use of thiophenol. It was not reported under other CVD conditions. Dense coatings were deposited by implementing a multilayer growth mode. Such coatings exhibit a high nanohardness of about 17 GPa. The δ-Cr metastable phase undergoes an irreversible structural transformation to bcc-Cr above 723 K. The mechanical properties of coatings are not affected by the structural transformation because of the similarity of their crystallographic structures (both cubic), their density very close (a volume contraction of only 0.4% during the transformation) and its low content. This metastable phase is a signature of the DLI-MOCVD process and it can be used as a tracer for Cr coatings operating in high temperature environment without loss of the basic properties

Effects of PDE4 inhibitors on lipopolysaccharide-induced priming of superoxide anion production from human mononuclear cells.

AIMS: Phosphodiesterase 4 (PDE4) inhibitors have been described as potent anti-inflammatory compounds, involving an increase in intracellular levels of cyclic 3',5'-adenosine monophosphate (AMP). The aim of this study was to compare the effects of selective PDE4 inhibitors, rolipram and RP 73-401 with the cell permeable analogue of cyclic AMP, dibutyryl-cyclic AMP (db-cAMP) and the anti-inflammatory cytokine interleukin-10 (IL-10) on superoxide anion production from peripheral blood mononuclear cells preincubated with lipopolysaccharide (LPS). MAJOR FINDINGS: We report that, after incubation of the cells with LPS, a large increase in superoxide anion production was observed. Rolipram or RP 73-401 (10(-8) to 10(-5) M) induced significant reductions of fMLP-induced superoxide anion production in cells incubated with or without LPS. The db-cAMP (10(-5) to 10(-3) M) also elicited dose-dependent inhibitions of the fMLP-induced superoxide anion production. In contrast, IL-10 (1 or 10 ng/ml) did not elicit a reduction in fMLP-induced superoxide anion production in both conditions. PRINCIPAL CONCLUSION: These results suggest that the inhibitory activity of PDE4 inhibitors on fMLP-induced production of superoxide anion production is mediated by db-cAMP rather than IL-10

Heat transfer intensification using a cellular automaton

Paper presented at the 5th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, South Africa, 1-4 July, 2007.The aim of this study is to propose an optimisation method for heat transfer in a complex configuration inspired from well known constructal theory. Two cases of optimisation will be presented here: the case of a square heater cooled by a single-sided heat sink and the case of a disc-shaped area to be cooled with a central heat sink. The method used for optimisation is a cellular automaton which can progressively modify the shape of a conductive path linked to the heat sink with very simple rules. The rules imitate natural morphogenesis: as motionless organisms can grow along nutrient or water gradients with roots and pseudopodia, the cellular automaton created here initiates growth around the conductive path where thermal gradients are high and initiates destruction of conductive matter where gradients are low, so that the amount of conductive matter remains constant. The actual limitations of this procedure are exposed.cs201

Chromium carbide growth at low temperature by a highly efficient DLI-MOCVD process in effluent recycling mode

The effect of direct recycling of effluents on the quality of CrxCy coatings grown by MOCVD using direct liquid injection (DLI) of bis(ethylbenzene)chromium(0) in toluene was investigated. The results are compared with those obtained using non-recycled solutions of precursor. Both types of coatings exhibit the same features. They are amorphous in the temperature range 673–823 K. They exhibit a dense and glassy-like microstructure and a high hardness (> 23 GPa). Analyses at the nanoscale revealed a nanocomposite microstructure consisting of free-C domains embedded in an amorphous Cr7C3 matrix characterized by strong interfaces and leading to an overall composition slightly higher than Cr7C3. The stiffness and strength of these interfaces are mainly due to at least two types of chemical bonds between Cr atoms and free-C: (i) Cr intercalation between graphene sheets and(ii) hexahapto η6-Cr bonding on the external graphene sheets of the free-C domains. The density of these interactions was found increasing by decreasing the concentration of the injected solution, as this occurred using a recycled solution. As a result, “recycled” coatings exhibit a higher nanohardness (29 GPa) than “new” coatings (23 GPa). This work demonstrates that using bis(arene)M(0) precursors, direct recycling of effluents is an efficient route to improve the conversion yield of DLI-MOCVD process making it cost-effective and competitive to produce protective carbide coatings of transition metals which share the same metal zero chemistry

Phosphodiesterase 4 inhibitors and db-cAMP inhibit TNF-α release from human mononuclear cells. Effects of cAMP and cGMP-dependent protein kinase inhibitors

We investigated the effects of specific inhibitors of cAMP-dependent protein kinase (PKA) and cGMP-dependent protein kinase (PKG) on the inhibitory activity of phosphodiesterase (PDE) type 4 inhibitors and of the cell permeable analogue of cAMP, db-cAMP on LPS-induced TNF-α release from human mononuclear cells. Incubation from 30 min of mononuclear cells with dbcAMP (10−5 to 10−3 M), rolipram (10−9 M to 10−5 M) or Ro 20-1724 (10−9 M to 10−5 M) significantly inhibited LPS-induced TNF-α release. When mononuclear cells were preincubated for 30 min with the selective PKA inhibitor, H89 (10−4 M), but not with the selective PKG inhibitor, Rp-8-pCPT-cGMPs (10−4 M), a significant reduction of the inhibitory effect of db-cAMP was noted. Thirty min incubation of mononuclear cells with Rp-8-pCPT-cGMPs induced a significant reduction of the inhibitory activities of both rolipram and Ro 20-1724 (10−9 to 10−5 M) on LPS-induced TNF-α release, whereas H89 elicited a moderate, but significant inhibition. The present data indicate that db-cAMP inhibits TNF-α release from human mononuclear cells through a PKA-dependent mechanism. In contrast, PDE 4 inhibitors elicit their in vitro anti-inflammatory activities via a PKG-dependent rather than PKA-dependent activation

éditorial : Art(s) & Espace(s) / Art(s) & Space(s)

Pour qui s’intéresse à la géographie et aux propositions qui émanent de ses chercheurs anglophones ou francophones, cela n’a pu échapper : les événements et les publications qui mêlent approche spatiale, artistes et productions artistiques se suivent et ne se ressemblent pas. Ce qui, il n’y a pas si longtemps, pouvait apparaître comme des pratiques et objets de recherche très marginaux, s’affirme désormais dans le paysage scientifique contemporain de la géographie sous la bannière encore mou..

éditorial : Art(s) & Espace(s) / Art(s) & Space(s)

Pour qui s’intéresse à la géographie et aux propositions qui émanent de ses chercheurs anglophones ou francophones, cela n’a pu échapper : les événements et les publications qui mêlent approche spatiale, artistes et productions artistiques se suivent et ne se ressemblent pas. Ce qui, il n’y a pas si longtemps, pouvait apparaître comme des pratiques et objets de recherche très marginaux, s’affirme désormais dans le paysage scientifique contemporain de la géographie sous la bannière encore mou..

The absence of reactive oxygen species production protects mice against bleomycin-induced pulmonary fibrosis

BACKGROUND: Reactive oxygen species and tissue remodeling regulators, such as metalloproteinases (MMPs) and their inhibitors (TIMPs), are thought to be involved in the development of pulmonary fibrosis. We investigated these factors in the fibrotic response to bleomycin of p47(phox )-/- (KO) mice, deficient for ROS production through the NADPH-oxidase pathway. METHODS: Mice are administered by intranasal instillation of 0.1 mg bleomycin. Either 24 h or 14 days after, mice were anesthetized and underwent either bronchoalveolar lavage (BAL) or lung removal. RESULTS: BAL cells from bleomycin treated WT mice showed enhanced ROS production after PMA stimulation, whereas no change was observed with BAL cells from p47(phox )-/- mice. At day 1, the bleomycin-induced acute inflammatory response (increased neutrophil count and MMP-9 activity in the BAL fluid) was strikingly greater in KO than wild-type (WT) mice, while IL-6 levels increased significantly more in the latter. Hydroxyproline assays in the lung tissue 14 days after bleomycin administration revealed the absence of collagen deposition in the lungs of the KO mice, which had significantly lower hydroxyproline levels than the WT mice. The MMP-9/TIMP-1 ratio did not change at day 1 after bleomycin administration in WT mice, but increased significantly in the KO mice. By day 14, the ratio fell significantly from baseline in both strains, but more in the WT than KO strains. CONCLUSIONS: These results suggest that NADPH-oxidase-derived ROS are essential to the development of pulmonary fibrosis. The absence of collagen deposition in KO mice seems to be associated with an elevated MMP-9/TIMP-1 ratio in the lungs. This finding highlights the importance of metalloproteinases and protease/anti-protease imbalances in pulmonary fibrosis