Modern pollen assemblages from grazed vegetation in the western Pyrenees, France: a numerical tool for more precise reconstruction of past cultural landscapes

International audienceModern pollen assemblages from grazed vegetation in the Pyrenees Mountains (France) were studied with the aim of providing a calibrated model for reconstructing past pastoral activities. The modern analogues were selected to cover the major gradients of grazing pressure and degree of openness. The vegetation was surveyed by means of the synusial integrated method, assessing the structure and the patchiness of the pastoral phytoceonoses. A correlative model (Redundancy analysis) was devised relating 61 modern pollen spectra with 37 explanatory vegetation and land-use variables. It was shown that wooded, open grazed and nitrophilous sites are clearly separated from one another and that the model can be simplified using three relevant vegetation types as explanatory variables: dry heathland, semi-open oak forest and overgrazed community, respectively related to gradients of openness, soil richness and grazing pressure. When reconstructing past pastoral activities with fossil pollen spectra, it is important to consider scale-dependent influences of plant species. Low frequencies of well-dispersed taxa such as Artemisia, Chenopodiaceae, Plantago lanceolata and Plantago major/media must be interpreted with care since they reflect more regional, rather than local, input into the pastoral landscape. In contrast, the simultaneous occurrence of Asteroideae, Cichorioideae, Cirsium-type, Galium-type, Ranunculaceae, Stellaria-type and Potentilla-type pollen is clearly related to grazing on a local scale. Calculation of Davis indices also shows that Cichorioideae, Galium-type and Potentilla-type indicate the very local presence of the corresponding plants. These pastoral plant indicators may have a limited geographical validity, ie, mountainous regions with crystalline bedrock, which may indeed also provide the framework for the application to fossil spectra of the modern pollen/vegetation/land-use models presented here

Globalization and the Growth of Chinese Cities

China experiences rapid growth in urbanization. This paper investigates whether openness may, ceteris paribus, partly explain the urbanization process. Trade openness and foreign direct investments are often regarded as important explanatory variables during the nineties. However, the impact of the later is expected to be positive, as FDI are mostly concentrated in few urban areas, whereas the impact of the former is a priori less clear. A cross section of 132 cities (data are averaged over the period 1992-1998) is used to carry out an econometric analysis. Trade openness appears only significant and negative for the sub-sample of coastal cities, when Beijing, Tianjin and Shanghai are excluded from the data. Foreign direct investments are significant and positive for the sub-sample of cities with more than one million inhabitants. These results contradict the common view of openness as a positive factor of urbanization in the nineties.urbanization, Trade, panel data, Openness, FDI, cities, China

Small scale structure in diffuse molecular gas from repeated FUSE and visible spectra of HD 34078

We present preliminary results from an ongoing program devoted to a study of small scale structure in the spatial distribution of molecular gas. Our work is based on multi-epoch FUSE and visible observations of HD34078. A detailed comparison of H2, CH and CH+ absorption lines is performed. No short term variations are seen (except for highly excited H2) but long-term changes in N(CH) are clearly detected when comparing our data to spectra taken about 10 years ago.Comment: 4 pages, 2 figures, To appear in the Proceedings of the XVII IAP Colloquium "Gaseous Matter in Galaxies and Intergalactic Space

La céramique antique de deux établissements ruraux en territoire ségusiave : Grand’Plantes à Fleurieux-sur-l’Arbresle et Les Fourches à Lentilly (Rhône)

Deux fermes antiques en territoire ségusiave, dont une particulièrement bien caractérisée, ont livré des lots de mobilier qui permettent de montrer l’évolution du faciès céramique depuis la fin du Ier s. av. J.-C. jusqu’au IIIe s. de notre ère. À proximité de la colonie romaine de Lugdunum, au sud, et de Forum Segusiavorum, la capitale de cité ségusiave, à l’est, les sites sont également dans l’aire d’influence de l’axe Rhône-Saône. L’étude des céramiques communes et une attention particulière aux pâtes ont révélé une grande variété de faciès morphologiques avec des influences de la vallée de la Loire, de Lyon et Vienne dans la vallée du Rhône mais aussi de la plaine de la Saône.Two Antique farms in the Segusiavi region, including one that is particularly well characterized, yielded artifact assemblages that show the evolution of the ceramic facies from the end of the 1st c. BC to the 3rd c. AD. Located near the Roman colony of Lugdunum to the south, and the Forum Segusiavorum, the capital of the Segusiavi city, to the east, the sites are also in the zone of influence of the Rhône-Saône axis. The study of the common ceramics, with specific attention paid to the clays, revealed a wide variety of morphological facies with influences from the Loire Valley, Lyon and Vienne in the Rhône Valley, as well as from the Saône plain.Die Keramikserien aus zwei antiken ländlichen Siedlungen auf dem Gebiet der Segusiaver, eine der beiden Siedlungen ist sehr charakteristisch, erlauben es die Entwicklung der Keramik vom Ende des 1. Jh. v. Chr. bis zum 3. Jh. n. Chr. zu nachzuverfolgen. Die Siedlungen liegen südlich der römischen Kolonie Lugdunum und östlich von Forum Segusiavorum, dem Hauptort der Segusiaver, und befinden sich zudem im Einflussbereich der Achse Rhône-Saône. Die Untersuchung der Gebrauchskeramik, bei der den verwendeten Tonen besondere Aufmerksamkeit gewidmet wurde, hat eine große morphologische Vielfalt mit Einflüssen des Loiretals, Lyon und Vienne im Rhonetal, doch auch der Saône-Ebene aufgezeigt

Gold Nanoparticle Uptake in Tumor Cells: Quantification and Size Distribution by sp-ICPMS

Gold nanoparticles (AuNPs) are increasingly studied for cancer treatment purposes, as they can potentially improve both control and efficiency of the treatment. Intensive research is conducted in vitro on rodent and human cell lines to objectify the gain of combining AuNPs with cancer treatment and to understand their mechanisms of action. However, using nanoparticles in such studies requires thorough knowledge of their cellular uptake. In this study, we optimized single particle ICPMS (sp-ICPMS) analysis to qualify and quantify intracellular AuNP content after exposure of in vitro human breast cancer cell lines. To this aim, cells were treated with an alkaline digestion method with 5% TMAH, allowing the detection of gold with a yield of 97% on average. Results showed that under our experimental conditions, the AuNP size distribution appeared to be unchanged after internalization and that the uptake of particles depended on the cell line and on the exposure duration. Finally, the comparison of the particle numbers per cell with the estimates based on the gold masses showed excellent agreement, confirming the validity of the sp-ICPMS particle measurements in such complex samples

La construction du site pédagogique numérique CHIMACTIV : analyse d'une coopération réussie entre enseignants

International audienceUn collectif d'enseignants inter-établissements s'est organisé pour concevoir et co-construire un site pédagogique numérique. L'équipe de conception initiale a fortement coopéré (au sein de chaque établissement et entre établissements) et interagi étroitement avec différents acteurs (cellules TICE, étudiants, prestataires externes) pour aboutir à une version bilingue du site. La volonté d'élargir et de diversifier le champ des utilisateurs (enseignants et étudiants) a conduit à ouvrir ce collectif à de nouveaux enseignants, afin de faire évoluer le site et compléter son contenu. Après une analyse de l'organisation mise en place, nous discuterons des obstacles à surmonter, des facteurs de réussite et du ressenti des enseignants ayant vécu cette coopération, avant de conclure sur ce qu'apporte l'aspect « numérique » des ressources développées dans la coopération entre enseignants sur la base de notre expérience

Bye bye les friches! Densifier la ville sur les friches, une panacée?

peer reviewedDensifier les friches, une panacée pour promouvoir la ville compacte ? Le collectif Inter-Friches interroge les différents modes de régulation des friches et les formes d'action publique qu'elles suscitent en France, en Belgique et en Suisse

Exploring Functional β-Cell Heterogeneity In Vivo Using PSA-NCAM as a Specific Marker

BACKGROUND:The mass of pancreatic beta-cells varies according to increases in insulin demand. It is hypothesized that functionally heterogeneous beta-cell subpopulations take part in this process. Here we characterized two functionally distinct groups of beta-cells and investigated their physiological relevance in increased insulin demand conditions in rats. METHODS:Two rat beta-cell populations were sorted by FACS according to their PSA-NCAM surface expression, i.e. beta(high) and beta(low)-cells. Insulin release, Ca(2+) movements, ATP and cAMP contents in response to various secretagogues were analyzed. Gene expression profiles and exocytosis machinery were also investigated. In a second part, beta(high) and beta(low)-cell distribution and functionality were investigated in animal models with decreased or increased beta-cell function: the Zucker Diabetic Fatty rat and the 48 h glucose-infused rat. RESULTS:We show that beta-cells are heterogeneous for PSA-NCAM in rat pancreas. Unlike beta(low)-cells, beta(high)-cells express functional beta-cell markers and are highly responsive to various insulin secretagogues. Whereas beta(low)-cells represent the main population in diabetic pancreas, an increase in beta(high)-cells is associated with gain of function that follows sustained glucose overload. CONCLUSION:Our data show that a functional heterogeneity of beta-cells, assessed by PSA-NCAM surface expression, exists in vivo. These findings pinpoint new target populations involved in endocrine pancreas plasticity and in beta-cell defects in type 2 diabetes