Extensive amenability and an application to interval exchanges

Extensive amenability is a property of group actions which has recently been used as a tool to prove amenability of groups. We study this property and prove that it is preserved under a very general construction of semidirect products. As an application, we establish the amenability of all subgroups of the group IET of interval exchange transformations that have angular components of rational rank~${\leq 2}$. In addition, we obtain a reformulation of extensive amenability in terms of inverted orbits and use it to present a purely probabilistic proof that recurrent actions are extensively amenable. Finally, we study the triviality of the Poisson boundary for random walks on IET and show that there are subgroups $G <IET$ admitting no finitely supported measure with trivial boundary.Comment: 28 page

Equipement de chasse, équipement domestique : une distinction efficace ? Réflexion sur la notion d'investissement technique dans les industries aurignaciennes

National audienceL'Aurignacien est associé à une série d'innovations majeures qui caractérisent, plus largement, l'ensemble du Paléolithique supérieur. Cela concerne notamment l'avènement de manifestations artistiques (mobiles ou pariétales), le développement de la parure et d'un équipement en matières dures animales. Notre propos a pour ambition de réfléchir à la façon dont peuvent être abordées certaines des manifestations socio-économiques susceptibles d'accompagner ce profond phénomène d'évolution culturelle. En l'occurrence, concentrant notre travail sur les productions lithiques et osseuses de plusieurs ensembles appartenant à l'Aurignacien ancien des Pyrénées et du Jura souabe, nous cherchons à discuter de la pertinence et de la valeur de la partition, entre équipement domestique et équipement de chasse. Avec l'Aurignacien, il semble que ces deux grands registres d'activités reposent sur la mise en œuvre de chaînes opératoires différentes, faisant appel à des concepts techniques spécifiques. Ils sont en outre intégrés à des stratégies économiques où chacun d'entre-eux tient une place propre, en particulier dans le domaine de l'industrie osseuse. Il serait toutefois trop simple de considérer que cette distinction, effective sur certains plans, recoupe de façon claire une quelconque hiérarchie en termes d'investissement technique et économique

Diversité des logiques de travail dans les exploitations maraîchères en circuits courts

Les circuits courts alimentaires font aujourd'hui l'objet d'une attention grandissante, aussi bien de la part des producteurs que des consommateurs. Fondés sur une réduction du nombre d'intermédiaires marchands, ces modes de commercialisation répondent à une forte demande de consommation locale et seraient susceptibles de constituer une voie de dynamisation de l'économie agricole locale. Ces systèmes participeraient de plus à un processus de revalorisation économique et sociale du métier d'agriculteur, notamment au travers des liens qu'ils induisent avec les consommateurs et de l'indépendance qu'ils confèrent aux producteurs dans l'exercice de leur activité. Cependant, une des principales limites de ces systèmes de commercialisation serait celle liée à l'organisation du travail et à la gestion du temps sur l'exploitation. Il est en effet souvent souligné que la gestion de la commercialisation combinée à la maitrise d'un système d'exploitation souvent complexe et diversifié entraine une surcharge de travail pour le producteur. Dans cette communication, nous nous intéresserons à la dimension " travail " dans les exploitations maraichères en circuits courts. Nous montrerons que les résultats en termes de temps de travail et de chiffres d'affaire des exploitations semblent dépendre du rapport que les agriculteurs entretiennent avec leur travail, au-delà du fait de commercialiser en circuits courts. Cette notion de rapport au travail sera d'abord vue comme une grille de lecture permettant de mieux cerner la diversité des exploitations maraichères en circuits courts. Elle nous permettra ensuite de mettre en évidence les différentes logiques de travail pouvant expliquer la variabilité des résultats technico-économiques et de soulever les principales problématiques liées à l'organisation du travail dans ces exploitations

Optimized Homomorphic Evaluation of Boolean Functions

We propose a new framework to homomorphically evaluate Boolean functions using the Torus Fully Homomorphic Encryption (TFHE) scheme. Compared to previous approaches focusing on Boolean gates, our technique can evaluate more complex Boolean functions with several inputs using a single bootstrapping. This allows us to greatly reduce the number of bootstrapping operations necessary to evaluate a Boolean circuit compared to previous works, thus achieving significant improvements in terms of performances. We define theoretically our approach which consists in adding an intermediate homomorphic layer between the plain Boolean space and the ciphertext space. This layer relies on so-called p-encodings embedding bits into Zp. We analyze the properties of these encodings to enable the evaluation of a given Boolean function and provide a deterministic algorithm (as well as an efficient heuristic) to find valid sets of encodings for a given function. We also propose a method to decompose any Boolean circuit into Boolean functions which are efficiently evaluable using our approach. We apply our framework to homomorphically evaluate various cryptographic primitives, and in particular the AES cipher. Our implementation results show significant improvements compared to the state of the art

Optimized Homomorphic Evaluation of Boolean Functions

We propose a new framework to homomorphically evaluate Boolean functions using the Torus Fully Homomorphic Encryption (TFHE) scheme. Compared to previous approaches focusing on Boolean gates, our technique can evaluate more complex Boolean functions with several inputs using a single bootstrapping. This allows us to greatly reduce the number of bootstrapping operations necessary to evaluate a Boolean circuit compared to previous works, thus achieving significant improvements in terms of performances. We define theoretically our approach which consists in adding an intermediate homomorphic layer between the plain Boolean space and the ciphertext space. This layer relies on so-called $p$-encodings embedding bits into $\mathbb{Z}_p$. We analyze the properties of these encodings to enable the evaluation of a given Boolean function and provides a deterministic algorithm (as well as an efficient heuristic) to find valid sets of encodings for a given function. We also propose a method to decompose any Boolean circuit into Boolean functions which are efficiently evaluable using our approach. We apply our framework to homomorphically evaluate various cryptographic primitives, and in particular the AES cipher. Our implementation results show significant improvements compared to the state of the art

Odorant metabolism catalyzed by olfactory mucosal enzymes influences peripheral olfactory responses in rats.

International audienceA large set of xenobiotic-metabolizing enzymes (XMEs), such as the cytochrome P450 monooxygenases (CYPs), esterases and transferases, are highly expressed in mammalian olfactory mucosa (OM). These enzymes are known to catalyze the biotransformation of exogenous compounds to facilitate elimination. However, the functions of these enzymes in the olfactory epithelium are not clearly understood. In addition to protecting against inhaled toxic compounds, these enzymes could also metabolize odorant molecules, and thus modify their stimulating properties or inactivate them. In the present study, we investigated the in vitro biotransformation of odorant molecules in the rat OM and assessed the impact of this metabolism on peripheral olfactory responses. Rat OM was found to efficiently metabolize quinoline, coumarin and isoamyl acetate. Quinoline and coumarin are metabolized by CYPs whereas isoamyl acetate is hydrolyzed by carboxylesterases. Electro-olfactogram (EOG) recordings revealed that the hydroxylated metabolites derived from these odorants elicited lower olfactory response amplitudes than the parent molecules. We also observed that glucurono-conjugated derivatives induced no olfactory signal. Furthermore, we demonstrated that the local application of a CYP inhibitor on rat olfactory epithelium increased EOG responses elicited by quinoline and coumarin. Similarly, the application of a carboxylesterase inhibitor increased the EOG response elicited by isoamyl acetate. This increase in EOG amplitude provoked by XME inhibitors is likely due to enhanced olfactory sensory neuron activation in response to odorant accumulation. Taken together, these findings strongly suggest that biotransformation of odorant molecules by enzymes localized to the olfactory mucosa may change the odorant's stimulating properties and may facilitate the clearance of odorants to avoid receptor saturation

Aromatase in the brain of teleost fish: expression, regulation and putative functions.

International audienceUnlike that of mammals, the brain of teleost fish exhibits an intense aromatase activity due to the strong expression of one of two aromatase genes (aromatase A or cyp19a1a and aromatase B or cyp19a1b) that arose from a gene duplication event. In situ hybridization, immunohistochemistry and expression of GFP (green fluorescent protein) in transgenic tg(cyp19a1b-GFP) fish demonstrate that aromatase B is only expressed in radial glial cells (RGC) of adult fish. These cells persist throughout life and act as progenitors in the brain of both developing and adult fish. Although aromatase B-positive radial glial cells are most abundant in the preoptic area and the hypothalamus, they are observed throughout the entire central nervous system and spinal cord. In agreement with the fact that brain aromatase activity is correlated to sex steroid levels, the high expression of cyp19a1b is due to an auto-regulatory loop through which estrogens and aromatizable androgens up-regulate aromatase expression. This mechanism involves estrogen receptor binding on an estrogen response element located on the cyp19a1b promoter. Cell specificity is achieved by a mandatory cooperation between estrogen receptors and unidentified glial factors. Given the emerging roles of estrogens in neurogenesis, the unique feature of the adult fish brain suggests that, in addition to classical functions on brain sexual differentiation and sexual behaviour, aromatase expression in radial glial cells could be part of the mechanisms authorizing the maintenance of a high proliferative activity in the brain of fish

Therapeutic Anticoagulant Does not Modify Thromboses Rate Vein after Venous Reconstruction Following Pancreaticoduodenectomy

Recommendations for anticoagulation following major venous reconstruction for pancreatic adenocarcinoma (PA) are not clearly established. The aim of our study was to find out the relation between postoperative anticoagulant treatment and thrombosis rate after portal venous resection. Materials and methods. Between 1986 and 2006, twenty seven portal vein resections were performed associated with pancreaticoduodenectomies (n = 27) (PD).We defined four types of venous resection: type I was performed 1 cm above the confluent of the superior mesenteric vein (SMV) (n = 12); type II lateral resection and venorrhaphy at the level of the confluent SMV (n = 12); type III (n = 1) resulted from a primary end-to-end anastomosis above confluent and PTFE graph was used for reconstruction for type IV (n = 2). Curative anticoagulant treatment was always indicated after type IV (n = 2) resection, and after resection of type II when the length of venous resection was longer than ≥2 cm. Results. Venous thrombosis rate reached: 0%, 41%, and 100% for type I, II, IV resections, respectively. Among them four patients received curative anticoagulant treatment. Conclusion. After a portal vein resection was achieved in the course of a PD, curative postoperative anticoagulation does not prevent efficiently the onset of thrombosis

Du Mésolithique au Néolithique en Méditerranée occidentale: l’impact africain - MeNeMOIA

[EN] Between the 8th and 5th millennia BC, the human societies of the Western Mediterranean underwent several major changes. The first occurred during the 7th millennium with the appearance of the ‘Second Mesolithic’. It can be seen mainly in the material productions of these populations, in particular their stone tool industries, by a fundamental change in production, operating sequences and technical procedures. Deeper changes in the social organization of these societies are also perceptible, in particular through changes in rites and funeral practices. The precise origin of these changes escapes us at present, but they seem to occur initially in North Africa before spreading rapidly along the Mediterranean shores and reaching Western Europe. A second major upheaval took place a few centuries later, with the appearance of the Neolithic. In this extensive process, the southern shores of the Mediterranean should not be ignored. Recent data suggest that, during the 6th millennium before our era, human communities practicing hunting and gathering and having acquired ceramic technology, occupied parts of the Maghreb. Interactions with spheres of the Impresso / Cardial complex occurred in southern Italy and, at the other end, southern Spain. This seems to be indicated by some traits of the technical systems of the first Neolithic communities of Andalusia. These hypotheses should now be tested by close examination of timelines and technical systems which if confirmed may offer a possible alternative to the strictly European scenarios. The international program of research, MeNeMOIA, financed for 2016 and 2017, will attempt to estimate the importance of a North African impact on European societies of recent prehistory (Second Mesolithic, Early Neolithic), a scenario breaking with the traditional scenario which, since decolonization, has recognized in Europe only movements of east-west diffusion and completely ignored any that might indicate movement from the south northward (or from the north southward) on both shores of the western Mediterranean.[FR] Entre les viiie et ve millénaires avant notre ère, les sociétés humaines du Bassin occidental de la Méditerranée connaissent plusieurs évolutions majeures. La première d’entre elles se déroule durant le viie millénaire avec l’apparition du «Second Mésolithique». Elle se matérialise principalement dans les productions matérielles de ces populations, et notamment dans leurs industries lithiques par un bouleversement des modes de production, des séquences opératoires et des gestes techniques. Des évolutions plus profondes, dans l’organisation sociale même de ces sociétés, sont également sensibles, notamment au travers de l’évolution des rites et pratiques funéraires. L’origine précise de ces évolutions nous échappe encore actuellement, mais elles semblent se produire initialement en Afrique du Nord avant de diffuser ensuite le long des rivages méditerranéens de manière rapide, et gagner ensuite l’ensemble de l’Europe occidentale. Un second bouleversement majeur se déroule quelques siècles après le précédent, avec l’apparition du Néolithique. Dans ce vaste processus, les rives sud de la Méditerranée ne doivent pas être ignorées. De récentes données suggèrent en effet que, durant le vie millénaire avant notre ère, des communautés humaines pratiquant chasse et cueillette et ayant acquis la technologie céramique occupaient certaines parties du Maghreb. Des interactions avec les sphères du complexe Impresso / Cardial ont ainsi pu voir le jour dans le Sud italien et, à l’autre extrémité, dans le sud de l’Espagne. C’est d’ailleurs ce que semblent montrer certains caractères des systèmes techniques des premières communautés néolithiques d’Andalousie. Ces hypothèses qu’il faut désormais confirmer par la confrontation étroite des chronologies et des systèmes techniques offrent donc une alternative possible aux scénarios classiques strictement européens. Le programme international de recherche MeNeMOIA, financé par l’IDEX toulousain pour 2016 et 2017, va donc s’attacher à évaluer l’importance des impacts nord-africains sur les sociétés européennes de la Préhistoire récente (Second Mésolithique, Néolithique ancien), scénario rompant avec les schémas traditionnels qui, depuis la décolonisation, se cantonnent à ne reconnaitre en Europe que des mouvements de diffusion est-ouest et ignorent complètement ceux allant du sud vers le nord (ou du nord vers le sud) de part et d’autre du Bassin occidental de la Méditerranée.Peer Reviewe