On price convergence in Eurozone

We investigate price level convergence with Germany in eleven countries belonging to the Eurozone between January 1970 and July 2011. Relying on smooth transition regression models, we show that the price convergence process is nonlinear, depending on the size of the price differential: for most countries, price convergence occurs only when price differentials with Germany exceed a certain threshold. Moreover, our findings put forward some heterogeneity across the Eurozone members in terms of price convergence speed, that can be explained by the evolution of price-competitiveness, rigidities in labor markets, but also by specialization patterns.price convergence, Eurozone, smooth transition regression models, half-life

Is price dynamics homogeneous across Eurozone countries?

The aim of this paper is to investigate whether price dynamics is homogeneous across the Eurozone countries. Relying on monthly data over the January 1970-July 2011 period, we test for the absolute purchasing power parity (PPP) hypothesis through the implementation of second-generation panel unit root and cointegration tests. Our results show that price dynamics are heterogeneous depending on both the time period and the considered group of countries. More specifically, while PPP is validated for the core EMU countries, this hypothesis does not hold for Northern peripheral economies. Turning to the Southern countries, PPP is observed only before the launch of the euro.price convergence, Eurozone, panel unit root tests, half-life

Dynamic behavior and microstructural properties of cancellous bone

The aim of the presented study is to identify some properties of the dynamic behavior of the cancellous bone and to identify the link between this mechanical behavior and the microstructural properties. 7 cylinders of bovine cancellous bone (diameter 41 mm, thickness 14 mm) were tested in quasi static loading (0.001 s-1), 8 in dynamic loading (1000 s-1) and 10 in dynamic loading (1500 s-1) with a confinement system. All the specimens were submitted to imaging before the tests (pQCT) in order to indentify two microstructural properties: Bone Volume / Total Volume ? BV/TV ? and Trabeculae Thickness ? Tb.Th. The behavior of bovine cancellous bone under compression exhibits a foam-type behavior over the whole range of strain rates explored in this study. The results show that for the quasi-static tests only the stresses are correlated with BV/TV. For the unconfined dynamic tests, the yield stress is correlated to BV/TV and the plateau stress to BV/TV and Tb.Th. For the confined tests, only the plateau stress is correlated to BV/TV and Tb.Th. The effect of strain rate is an increase of the yield stress and the plateau stress. The confinement has an effect on the measured values of compression stresses that confirms the importance of marrow flow in the overall behavior

Des bibliothèques décomplexées

On ne se lasse pas de revenir aux Pays-Bas. La visite 2011, complémentaire des précédentes, aura permis de visiter des bibliothèques moins connues mais tout aussi décapantes : architecture extensible à volonté (Leyde), organisation des espaces sur un modèle commercial (Lelystad, Almere) ou zen (Utrecht)… de quoi stimuler l’imagination

Universal classification of twisted, strained and sheared graphene moir\'e superlattices

Moir\'e superlattices in graphene supported on various substrates have opened a new avenue to engineer graphene's electronic properties. Yet, the exact crystallographic structure on which their band structure depends remains highly debated. In this scanning tunneling microscopy and density functional theory study, we have analysed graphene samples grown on multilayer graphene prepared onto SiC and on the close-packed surfaces of Re and Ir with ultra-high precision. We resolve small-angle twists and shears in graphene, and identify large unit cells comprising more than 1,000 carbon atoms and exhibiting non-trivial nanopatterns for moir\'e superlattices, which are commensurate to the graphene lattice. Finally, a general formalism applicable to any hexagonal moir\'e is presented to classify all reported structures.Comment: 14 pages, 6 figure

Reconstructing historical trends of polycyclic aromatic hydrocarbon deposition in a remote area of Spain using herbarium moss material

Herbarium mosses from 1879-1881, 1973-1975 and 2006-2007 were used to investigate the historical changes of atmospheric deposition of polycyclic aromatic hydrocarbons (PAHs) at a remote site located in Northern Spain. Natural abundance of nitrogen and carbon isotopes was also measured in order to assess the evolution of emissions from anthropogenic sources. Nitrogen concentrations, 13C, 13N and PAH levels were significantly higher in 19th century samples with respect to the present century samples. Moreover, PAH distribution varied over the centuries, following a tendency of light PAH enrichment. The carbon, nitrogen and PAH levels measured in the mosses tally with the historic evolution of anthropogenic emissions in the area, mainly influenced by changes of economic activities, domestic heating and road traffic density. Mosses provided by herbaria seem to offer the possibility to study long-term temporal evolution of atmospheric PAH deposition

Expression of neurogenin3 reveals an islet cell precursor population in the pancreas

Differentiation of early gut endoderm cells into the endocrine cells forming the pancreatic islets of Langerhans depends on a cascade of gene activation events controlled by transcription factors including the basic helix-loop-helix (bHLH) proteins. To delineate this cascade, we began by establishing the position of neurogenin3, a bHLH factor found in the pancreas during fetal development. We detect neurogenin3 immunoreactivity transiently in scattered ductal cells in the fetal mouse pancreas, peaking at embryonic day 15.5. Although not detected in cells expressing islet hormones or the islet transcription factors Isl1, Brn4, Pax6 or PDX1, neurogenin3 is detected along with early islet differentiation factors Nkx6.1 and Nkx2.2, establishing that it is expressed in immature cells in the islet lineage. Analysis of transcription factor-deficient mice demonstrates that neurogenin3 expression is not dependent on neuroD1/BETA2, Mash1, Nkx2.2, Nkx6.1, or Pax6. Furthermore, early expression of neurogenin3 under control of the Pdx1 promoter is alone sufficient to drive early and ectopic differentiation of islet cells, a capability shared by the pancreatic bHLH factor, neuroD1/BETA2, but not by the muscle bHLH factor, MyoD. However, the islet cells produced in these transgenic experiments are overwhelmingly α cells, suggesting that factors other than the bHLH factors are required to deviate from a default α cell fate. These data support a model in which neurogenin3 acts upstream of other islet differentiation factors, initiating the differentiation of endocrine cells, but switching off prior to final differentiation. The ability to uniquely identify islet cell precursors by neurogenin3 expression allows us to determine the position of other islet transcription factors in the differentiation cascade and to propose a map for the islet cell differentiation pathway

Impact of the chemical composition of poly-substituted hydroxyapatite particles on the in vitro pro-inflammatory response of macrophages

International audienceTo improve the biological properties of calcium phosphate (CaP) bone substitute, new chemical compositions are under development. In vivo such materials are subject to degradation that could lead to particles release and inflammatory reactions detrimental to the bone healing process. This study aimed at investigating the interactions between a murine macrophage cell line (RAW 264.7) and substituted hydroxyapatite particles presenting promising biological properties. Micron size particles of stoichiometric and substituted hydroxyapatites (CO 3 substitution for PO 4 and OH; SiO 4 substitution for PO 4; CO 3 and SiO 4 co-substitution) were obtained by aqueous precipitation followed by spray drying. Cells, incubated with four doses of particles ranging from 15 to 120 µg/mL, revealed no significant LDH release or ROS production, indicating no apparent cytotoxicity and no oxidative stress. TNF-α production was independent of the chemistry of the particles; however the particles elicited a significant dose-dependent pro-inflammatory response. As micron size particles of these hydroxyapatites could be at the origin of inflammation, attention must be paid to the degradation 2 behavior of substituted hydroxyapatite bone substitute in order to limit, in vivo, the generation of particulate debris

Les compétences distinctives en fonction de la largeur et de la profondeur des connaissances : le cas des systèmes de surveillance du trafic aérien au sein d’Eurocontrol.

Les compétences technologiques et organisationnelles sont difficiles à identifier, en particulier dans des périodes de changement de contexte. Si la littérature sur les compétences et les connaissances est riche, la possibilité d’opérationnaliser les concepts demeure souvent limitée. En particulier les organisations sont souvent démunies pour répondre aux questions suivantes : • Comment les compétences de l’organisation doivent-elles évoluer face à un changement de contexte ? • Quelles compétences l’organisation doit préserver en interne ou au contraire externaliser ? • Quelles sont les incidences d’une identification des compétences distinctives de l’organisation au niveau des compétences individuelles ? Cet article propose une méthode d’identification des compétences technologiques et organisationnelles et une analyse de leur évolution à partir des concepts de profondeur et la largeur des connaissances actionnées par les organisations. Nous proposons d’identifier la profondeur des connaissances en analysant la capacité de l’organisation à identifier et résoudre les problèmes qu’elle rencontre. La largeur des connaissances est analysée à partir de la diversité des connaissances concrètes et abstraites mobilisées par l’organisation dans la résolution de problèmes. Cette approche permet non seulement de caractériser les compétences au niveau de l’organisation mais aussi de faire le lien avec les compétences individuelles. L’analyse proposée apporte un éclairage sur l’évolution de la frontière des organisations dans les environnements turbulents. Cette recherche est fondée sur une méthode de recherche intervention réalisée au sein de l’unité SPS d’Eurocontrol, organisation inter-gouvernementale européenne en charge de missions dans le cadre de la sécurité de la navigation aérienne. Elle est confrontée à une évolution de son environnement aux plans économique, technologique et institutionnel. C’est dans ce contexte qu’a été menée une réflexion sur le positionnement stratégique quant aux systèmes et produits de surveillance.Compétences; connaissances; résolution de problèmes; environnements turbulents;