La fabrique d’Archipel (1971-1982)

L’histoire de la revue Archipel avec les cahiers, les dictionnaires, a cinquante ans aujourd’hui. Cela signifie que l’essentiel de son histoire relève d’une génération qui s’en va, ou qui s’en est déjà allée, en tout cas que les lecteurs d’aujourd’hui ne peuvent pratiquement pas connaître. Qui plus est, l’histoire des revues n’est pas un genre très prisé. Elle s’efface derrière les auteurs comme si son autonomie était limitée et comme s’il ne pouvait y être question que de débats d’arrière-cu..

Adolphe Combanaire (1859-1939). La gloire de l’explorateur.

Adolphe Combanaire (1859-1939) est surtout connu pour sa traversée de Bornéo en 1898 dans des conditions périlleuses et rocambolesques. Il illustre un type particulier d’explorateur, qui se développe à la fin du XIXe siècle sur le vecteur des entreprises coloniales. Mais alors que la plupart des voyageurs se protègent par des missions de la Société de géographie ou de l’Instruction publique, Adolphe Combanaire, lui, s’est entiché de la gutta percha qui commence à manquer dramatiquement pour les câbles téléphoniques. Il explore seul l’Asie du Sud-Est en joignant avec succès l’entreprise à l’aventure. Mais en même temps il veille soigneusement à sa réputation d’intrépidité par la publication du récit de ses aventures de Bornéo à Saïgon dans le Journal des voyages. Le dernier chapitre de ce parcours mouvementé se déplace sur le front de la Grande Guerre où il perd un bras. La fin de sa vie à Châteauroux est consacrée à ferrailler dans la politique locale, pour la défense des Poilus.Adolphe Combanaire (1859-1939) is best known for his journey through Borneo in 1898 under dangerous and incredible conditions. He represents a particular type of explorer that developed in the late nineteenth century in the wake of colonial companies. But while most travelers operated through missions organized under auspices of the Society of Geography or the Ministry of Public Education, Adolphe Combanaire took a shine to the gutta percha, which began to run out dramatically in the making of telephone cables. He explored Southeast Asia alone, successfully combining business and adventure. But at the same time he carefully made sure to maintain his reputation for fearlessness by publishing the story of his adventures from Borneo to Saigon in the Journal des voyages. The last chapter of this turbulent journey shifted to the front lines of the First World War, during which he lost an arm. Near the end of his life, he lived in Chateauroux crossing swords in local politics in defense of the Poilus

In memoriam : Christian Pelras (1934-2014)

Christian Pelras était l’un des fondateurs de la revue Archipel. Avec sa disparition s’arrête une longue collaboration de quarante-trois années qui correspondent à l’émergence de l’Insulinde dans la recherche française. Il était en quelque sorte le dernier des pionniers. Mais au moment d’écrire un aperçu de sa carrière, il paraît difficile de le cerner parce qu’il a été un homme aux fidélités multiples, aux activités diversifiées. Il a été attentif aux hommes, aux objets, aux techniques, arpe..

Polynomial growth of volume of balls for zero-entropy geodesic systems

The aim of this paper is to state and prove polynomial analogues of the classical Manning inequality relating the topological entropy of a geodesic flow with the growth rate of the volume of balls in the universal covering. To this aim we use two numerical conjugacy invariants, the {\em strong polynomial entropy $h_{pol}$} and the {\em weak polynomial entropy $h_{pol}^*$}. Both are infinite when the topological entropy is positive and they satisfy $h_{pol}^*\leq h_{pol}$. We first prove that the growth rate of the volume of balls is bounded above by means of the strong polynomial entropy and we show that for the flat torus this inequality becomes an equality. We then study the explicit example of the torus of revolution for which we can give an exact asymptotic equivalent of the growth rate of volume of balls, which we relate to the weak polynomial entropy.Comment: 22 page

What does the Covid-19 crisis reveal about economics and the economy? Introduction to this issue

Just a year after it was announced that a new virus had been discovered in the city of Wuhan, China, the world is no longer the same. The transformations wrought by the pandemic and the collective responses to it (lockdown of populations, drastic cuts in the movement of goods and more widely in economic and social activity) will entail structural effects. However, it is difficult to get a handle on the scope and nature of those effects. The Revue de la régulation posted a call for papers to j..

Nemesia Root Hair Response to Paper Pulp Substrate for Micropropagation

Agar substrates for in vitro culture are well adapted to plant micropropagation, but not to plant rooting and acclimatization. Conversely, paper-pulp-based substrates appear as potentially well adapted for in vitro culture and functional root production. To reinforce this hypothesis, this study compares in vitro development of nemesia on several substrates. Strong differences between nemesia roots growing in agar or in paper-pulp substrates were evidenced through scanning electron microscopy. Roots developed in agar have shorter hairs, larger rhizodermal cells, and less organized root caps than those growing on paper pulp. In conclusion, it should be noted that in this study, in vitro microporous substrates such as paper pulp lead to the production of similar root hairs to those found in greenhouse peat substrates. Consequently, if agar could be used for micropropagation, rooting, and plant acclimatization, enhancement could be achieved if rooting stage was performed on micro-porous substrates such as paper pulp

Ice-sheet melt drove methane emissions in the Arctic during the last two interglacials

Circum-Arctic glacial ice is melting in an unprecedented mode, and release of currently trapped geological methane may act as a positive feedback on ice-sheet retreat during global warming. Evidence for methane release during the penultimate (Eemian, ca. 125 ka) interglacial, a period with less glacial sea ice and higher temperatures than today, is currently absent. Here, we argue that based on foraminiferal isotope studies on drill holes from offshore Svalbard, Norway, methane leakage occurred upon the abrupt Eurasian ice-sheet wastage during terminations of the last (Weichselian) and penultimate (Saalian) glaciations. Progressive increase of methane emissions seems to be first recorded by depleted benthic foraminiferal δ13C. This is quickly followed by the precipitation of methane-derived authigenic carbonate as overgrowth inside and outside foraminiferal shells, characterized by heavy δ18O and depleted δ13C of both benthic and planktonic foraminifera. The similarities between the events observed over both terminations advocate for a common driver for the episodic release of geological methane stocks. Our favored model is recurrent leakage of shallow gas reservoirs below the gas hydrate stability zone along the margin of western Svalbard that can be reactivated upon initial instability of the grounded, marine-based ice sheets. Analogous to this model, with the current acceleration of the Greenland ice melt, instabilities of existing methane reservoirs below and nearby the ice sheet are likely

Impact of gneissic layering and localized incipient melting upon melt flow during experimental deformation of migmatites

International audienceIn this study, we test experimentally the role of compositional layering as a key parameter for controlling melt flow in a natural migmatite during coaxial deformation. We performed in – situ pure-shear experiments on two natural gneisses. The first gneiss is weakly foliated with minerals homogenously distributed. The second gneiss shows a pronounced compositional layering of alternating quartz – feldspar – rich and biotite – muscovite – rich layers. Experimental conditions were selected to obtain homogeneous melt distribution in the homogeneous gneiss and heterogeneous melt distribution in the layered gneiss. Initial melt distribution is not modified by deformation in experiments on the homogeneous gneiss, implying that melting products did not migrate from their initiation sites. In contrast, melt flowed in shear zones or in inter-boudin positions during experimental deformation of the heterogeneous gneiss. These experiments attest to the strong influence of initial gneissic layering on melting pattern, melt segregation and flow during deformation of partially molten rocks

Neurotrophins are expressed in giant cell arteritis lesions and may contribute to vascular remodeling

International audienceIntroduction: Giant cell arteritis (GCA) is characterized by intimal hyperplasia leading to ischaemic manifestations that involve large vessels. Neurotrophins (NTs) and their receptors (NTRs) are protein factors for growth, differentiation and survival of neurons. They are also involved in the migration of vascular smooth muscle cells (VSMCs). Our aim was to investigate whether NTs and NTRs are involved in vascular remodelling of GCA.Methods: We included consecutive patients who underwent a temporal artery biopsy for suspected GCA. We developed an enzymatic digestion method to obtain VSMCs from smooth muscle cells in GCA patients and controls. Neurotrophin protein and gene expression and functional assays were studied from these VSMCs. Neurotrophin expression was also analysed by immunohistochemistry in GCA patients and controls.Results: Whereas temporal arteries of both GCA patients (n = 22) and controls (n = 21) expressed nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), tropomyosin receptor kinase B (TrkB) and sortilin, immunostaining was more intense in GCA patients, especially in the media and intima, while neurotrophin-3 (NT-3) and P75 receptor (P75NTR) were only detected in TA from GCA patients. Expression of TrkB, a BDNF receptor, was higher in GCA patients with ischaemic complications. Serum NGF was significantly higher in GCA patients (n = 28) vs. controls (n = 48), whereas no significant difference was found for BDNF and NT-3. NGF and BDNF enhanced GCA-derived temporal artery VSMC proliferation and BDNF facilitated migration of temporal artery VSMCs in patients with GCA compared to controls.Conclusions: Our results suggest that NTs and NTRs are involved in vascular remodelling of GCA. In GCA-derived temporal artery VSMC, NGF promoted proliferation and BDNF enhanced migration by binding to TrkB and p75NTR receptors. Further experiments are needed on a larger number of VSMC samples to confirm these results