Une maquette trimestrielle de l’économie française avec anticipations rationnelles et concurrence monopolistique

L’article présente une maquette dynamique, chiffrée sur données trimestrielles de l’économie française, décrivant une situation de concurrence monopolistique à la fois sur le marché des biens et sur celui du travail. Sur ce dernier existe un effet de persistance conforme à la théorie « insider-outsider ». Le modèle est bouclé par la prise en compte de la consommation des ménages (revenu permanent) ainsi que des dépenses publiques et des échanges extérieurs. Après avoir étudié les propriétés de long terme de la maquette et vérifié les conditions d’existence et d’unicité de trajectoires d’anticipations rationnelles au voisinage de la solution stationnaire, des multiplicateurs dynamiques correspondant à des chocs transitoires non anticipés sont calculés et interprétés.We present a small size dynamic macroeconomic model, numerically calibrated on quarterly French data, describing an economy working under imperfect competition on both labour and goods markets. The labour market exhibits a persistence effect relying on the insider-outsider theory. The closure of the model is obtained by household consumption (permanent income), by public spendings and by foreign trade. The long run properties of the model and the conditions for a unique rational expectations path in the neighbourhood of the steady state are successively analysed before computing and interpreting the dynamic multipliers associated with non anticipated transitory shocks

Restauration réussie à Toulouse

Pionnière en 1935, la bibliothèque de Toulouse était devenue inadaptée à l’évolution des services, tout en acquérant une dimension patrimoniale. Inscrite aux monuments historiques, elle est considérée comme l’un des témoignages les plus représentatif de l’architecture publique des années 1930. L’opération BMVR l’a dégagée de ses fonctions de lecture publique, transférées à la nouvelle médiathèque centrale José- Cabanis, permettant de recentrer « la BM de Périgord » sur l’étude et le patrimoine, d’où une nouvelle appellation, BEP. Les travaux entrepris depuis 1999 se sont achevés en février dernier

Découvertes fortuites de stèles protohistoriques en Rouergue méridional

Trois sites du Rouergue méridional ont livré 13 stèles protohistoriques du premier âge du Fer, se rattachant à celles du midi de la France tout en constituant un groupe stylistique original. L’ensemble le plus important provient du promontoire des Touriès près du hameau du Vialaret (Saint-Jean et Saint-Paul, Aveyron). Il comprend 10 stèles, dont près de la moitié sont décorées et une statue d’un guerrier en ronde-bosse, probablement muni d’une cuirasse souple avec kardiophylax. Il s’agit d’un torse, stylistiquement proche du buste du Marduel (Saint-Bonnet-du-Gard), appartenant à une statuaire précoce parfois qualifiée « d’école du Languedoc oriental » en raison de sa répartition géographique. Les stèles décorées des trois sites rouergats semblent présenter une évolution de l’image figurative initiale du guerrier des Touriès, sans doute dans le cadre d’un culte héroïque, selon un schéma peut-être transposable au reste du Midi, en tout cas à une stèle décorée de l’oppidum de la Ramasse (Clermont-l’Hérault).Thirteen protohistorical carved slabs, dating to the first Iron Age and discovered in southern Rouergue, can be related to those of Mediterranean France, but seem to represent an original stylistic group. The most important group comes from the promontory of Touriès, near the village of Vialaret (Saint-Jean et Saint Paul, Aveyron). It comprises 10 carved slabs, half of which are decorated and a warrior sculpture on which is probably figured a flexible armour and a kardiophylax. It is a torso, stylistically similar to the one discovered in Marduel (Saint-Bonnet-du-Gard), which belongs to an early statuary sometimes called « school of eastern Languedoc » given it’s geographical distribution. The steles of these three sites seem to show an evolution of the initial figurative image of the warrior of Touries, perhaps within the scope of a hero cult, according to a schema which may be applied to the rest of Mediterranean France, at least to the decorated stela from the Hill-fort of la Ramasse (Clermont-l’Hérault)

Step-by-step investigation of degradation mechanisms induced by CMAS attack on YSZ materials for TBC applications

Over the past decades, Thermal Barrier Coatings (TBCs) have become essential parts in gas turbine engines. In working conditions, TBCs are subject to many kinds of degradation (erosion, foreign object damage (F.O.D), oxidation, etc.) which deteriorate integrity and mechanical properties of thewhole system.Moreover, with the aim to increase the turbine inlet temperature, a new type of damage has been highlighted: corrosion by molten Calcium–Magnesium–Alumino Silicates, better known as CMAS. In this paper, interactions between yttriastabilized zirconia (YSZ) materials synthesized via sol–gel process and synthetic CMAS powder were investigated via a step-by-step methodology. The approach was conducted starting from the more severe conditions of interactions and then gradually gets closer to the interactions taking place in service. It was proved that CMAS can induce faster densification of the ceramic leading to a loss of strain tolerance of the protective coating. Besides, a dissolution/re-precipitationmechanismcan also take place between YSZ andCMAS leading to the transformation of the initial tetragonal yttria-stabilized zirconia into globular particles of monoclinic zirconia. CMAS were also found to infiltrate the entire thickness of both EBPVD and sol–gel YSZ coatings at 1250 °C for 1 h. Nevertheless, the original non-oriented microstructure provided by sol–gel route leads to a different way of interaction due to the high reactivity of sol–gel precursors and materials. The behaviors of EBPVD and sol–gel coatings under CMAS exposure are discussed in this paper

Stimulating effect of diacerein on TGF-β1 and β2 expression in articular chondrocytes cultured with and without interleukin-1

AbstractObjective: Diacetylrhein or diacerein has shown efficacy in the treatment of both major forms of osteoarthritis (OA), coxarthrosis as well as gonarthrosis, improving clinical symptoms of the disease (pain reduction and algo-functional index). Both in-vitro and animal models studies suggest that diacerein may have also disease-modifying effects. The drug exerts inhibitory effects on interleukin-1-induced expression of cartilage degrading enzymes. However, its mechanism of action is not completely understood. In view of the role that could play the transforming growth factor (TGF)-β system in the repair potentialities of OA cartilage, we studied the effect of diacerein on the expression of TGF-β isoforms 1, 2 and 3 and that of their receptor types I and II in cultured bovine chondrocytes.Methods: Cultured bovine articular chondrocytes were treated with 10−5mdiacerein, 10ng/ml IL-1β or the combination diacerein+interleukin (IL)-1, and the expression of both TGF-β isoforms 1, 2 and 3 and that of their receptors TβR-I and TβR-II was determined by Northern-blot and reverse transcriptase-polymerase chain reaction (RT-PCR). Cell transfections of cDNA constructs containing sequences of the 5′-upstream region of TGF-β1 promoter were also performed to determine their transcriptional activity in diacerein-treated cultures.Results: The data indicated that diacerein enhances the expression of TGF-β1 and TGF-β2. This effect was also found in the presence of IL-1, albeit with smaller intensity. In contrast, the levels of TGF-β3 and receptors I and II remained unaffected or slighty modified by the compound. Treatment of cells transiently transfected with TGF-β1 promoter constructs suggested that the stimulating effect on TGF-β1 expression is mediated by the region −1038 to −1132base pars.Conclusion: The results suggest that diacerein effects on matrix synthesis and turn-over previously reported in cultured articular chondrocytes might be explained in part by the ability of the drug to enhance TGF-β1 and TGF-β2 expression in these cells. This mechanism of action may account for the potential disease-modifying properties of diacerein and might give clues as to how future anti-osteoarthritic drugs should be designed

Comparative Effects of Interleukin-1 and Tumor Necrosis Factor-α on Collagen Production and Corresponding Procollagen mRNA Levels in Human Dermal Fibroblasts

The effects of recombinant human Interleukin-1α (IL-1α), Interleukin-1β (IL-1β), and Tumor Necrosis Factor-α (TNF-α) on collagen biosynthesis were studied in vitro using dermal fibroblast cultures. Both forms of IL-1 and TNF-α induced a dose-dependent inhibition of both types I and III collagen synthesis, as measured by radioimmunoassay, gel electrophoresis, or collagenase-sensitive material. This effect was accompanied by a significant release of postaglandin E2 into the culture medium. However, indomethacin, a potent inhibitor of prostaglandin synthesis, could not prevent the inhibitory effect of the three cytokines on collagen synthesis.Measurement of type I and type III procollagen mRNA levels in IL-1 treated cells revealed that both IL-1α and IL-1β were potent enhancers of procollagen gene expression at pre-translational level. On the other hand, TNF-α was found to reduce the steady-state levels of type I and III procollagen mRNA in a dose-dependent manner.Quantitation of IL-1β and TNF-α transcripts following TNF-α treatment of fibroblasts indicated that this cytokine can induce IL-1β gene expression in these cells. By contrast, TNF-α mRNA remained at a constant level after TNF-α exposure.These data suggest that IL-1 and TNF-α, two cytokines that share several biologic activities, modulate collagen deposition in dermal fibroblasts by mechanisms that are clearly different: TNF-α appears to act at a transcriptional level to inhibit collagen synthesis, whereas IL-1 inhibitory action involves important translational regulation, still unknown, that counterbalances its stimulatory effect on procollagen mRNA levels. Moreover, our data suggest the existence of local fibroblastic cytokine production that may be involved in the modulation of extracellular matrix deposition

Human collagen Krox up-regulates type I collagen expression in normal and scleroderma fibroblasts through interaction with Sp1 and Sp3 transcription factors.

Despite several investigations, the transcriptional mechanisms that regulate the expression of both type I collagen genes (COL1A1 and COL1A2) in either physiological or pathological situations, such as scleroderma, are not completely known. We have investigated the role of hc-Krox transcription factor on type I collagen expression by human dermal fibroblasts. hc-Krox exerted a stimulating effect on type I collagen protein synthesis and enhanced the corresponding mRNA steady-state levels of COL1A1 and COL1A2 in foreskin fibroblasts (FF), adult normal fibroblasts (ANF), and scleroderma fibroblasts (SF). Forced hc-Krox expression was found to up-regulate COL1A1 transcription through a -112/-61-bp sequence in FF, ANF, and SF. Knockdown of hc-Krox by short interfering RNA and decoy strategies confirmed the transactivating effect of hc-Krox and decreased substantially COL1A1 transcription levels in all fibro-blast types. The -112/-61-bp sequence bound specifically hc-Krox but also Sp1 and CBF. Attempts to elucidate the potential interactions between hc-Krox, Sp1, and Sp3 revealed that all of them co-immunoprecipitate from FF cellular extracts when a c-Krox antibody was used and bind to the COL1A1 promoter in chromatin immunoprecipitation assays. Moreover, hc-Krox DNA binding activity to its COL1A1-responsive element is increased in SF, cells producing higher amounts of type I collagen compared with ANF and FF. These data suggest that the regulation of COL1A1 gene transcription in human dermal fibroblasts involves a complex machinery that implicates at least three transcription proteins, hc-Krox, Sp1, and Sp3, which could act in concert to up-regulate COL1A1 transcriptional activity and provide evidence for a pro-fibrotic role of hc-Krox