Relative and interactive effects of plant and grazer richness in a benthic marine community

The interactive effects of changing biodiversity of consumers and their prey are poorly understood but are likely to be important under realistic scenarios of biodiversity loss and gain. We performed two factorial manipulations of macroalgal group (greens, reds, and browns) and herbivore species (amphipods, sea urchin, and fish) composition and richness in outdoor mesocosms simulating a subtidal, hard-substratum estuarine community in North Carolina, USA. In the experiment where grazer richness treatments were substitutive, there were no significant effects of algal or herbivore richness on final algal biomass. However, in the experiment in which grazer treatments were additive (i.e., species-specific densities were held constant across richness treatments), we found strong independent and interactive effects of algal and herbivore richness. Herbivore polycultures reduced algal biomass to a greater degree than the sum of the three herbivore monocultures, indicating that the measured grazer richness effects were not due solely to increased herbivore density in the polycultures. Taking grazer density into account also revealed that increasing algal richness dampened grazer richness effects. Additionally, the effect of algal richness on algal biomass accumulation was far stronger when herbivores were absent, suggesting that grazers can utilize the increased productivity and mask the positive effects of plant biodiversity on primary production. Our results highlight the complex independent and interactive effects of biodiversity between adjacent trophic levels and emphasize the importance of performing biodiversity-ecosystem functioning experiments in a realistic multi-trophic context

Grimage: markerless 3D interactions

International audienceGrimage glues multi-camera 3D modeling, physical simulation and parallel execution for a new immersive experience. Put your hands or any object into the interaction space. It is instantaneously modeled in 3D and injected into a virtual world populated with solid and soft objects. Push them, catch them and squeeze them

Comment développer un antidépresseur au mécanisme d’action innovant : l’exemple de l’agomélatine

Divers axes de recherche ont été suivis pour obtenir de nouveaux traitements de la dépression plus efficaces, mieux tolérés et d’action plus rapide. Parmi ces axes de recherche, la mélatonine, synchronisateur endogène des rythmes biologiques chez les mammifères, suscite un intérêt croissant dans la mesure où la désorganisation des rythmes circadiens est caractéristique d’un grand nombre de troubles de l’humeur. L’agomélatine est un antidépresseur qui se distingue par des propriétés agonistes pour les récepteurs mélatoninergiques (MT1 et MT2) ; ses propriétés agonistes ont été confirmées lors d’études in vivo, l’agomélatine améliorant les perturbations des rythmes circadiens observés dans différents modèles animaux. La propriété antidépressive de l’agomélatine a été mise en évidence dans plusieurs modèles animaux validés, dont les tests de la nage forcée, de la résignation acquise ou du stress chronique modéré. De façon tout à fait intéressante, l’activité antidépressive de l’agomélatine ne repose pas uniquement sur une action chronobiotique : en fait, l’agomélatine présente une activité antagoniste sur les récepteurs 5-HT2C, et ce aux doses antidépressives. Par ailleurs, l’absence d’affinité de l’agomélatine vis-à-vis d’un large éventail de récepteurs lui confère un excellent profil de sécurité, particulièrement avantageux par rapport aux antidépresseurs déjà sur le marché (pas de désordres gastro-intestinaux ni de perturbations de la fonction sexuelle ou du sommeil). L’agomélatine inaugure donc un nouveau concept dans le traitement de la dépression.There are now many potentials for the development of more effective, better tolerated, and more rapidly acting antidepressants acting in association and/or beyond the monoamine hypothesis. One of these possibilities is the development of antidepressant drugs with melatonin agonist property. This holds much promise since various affective disorders, including depression, are characterized by abnormal patterns of circadian rhythms. In line with this, the melatoninergic agonist properties of agomelatine, an antidepressant with proven clinical efficacy, may represent a new concept for the treatment of depression. By way of behavioral studies in rodents, it has been shown that administration of agomelatine can mimic the action of melatonin in the synchronization of circadian rhythm patterns. Interest in agomelatine has increased in recent times due to its prospective use as a novel antidepressant agent, as demonstrated in a number of animal studies using well-validated animal models of depression (including the forced swimming test, the learned helplessness, the chronic mild stress). Interestingly, the melatoninergic agonist property of agomelatine may not, alone, be sufficient to sustain its clear antidepressant-like activity. Recent results from receptor binding and in vivo studies gave support to the notion that agomelatine’s effects are also mediated via its function as a competitive antagonist at the 5-HT2C receptor. Finally, thanks to its absence of binding with a broad range of receptors and enzymes, agomelatine is particularly safe and devoid of all the deleterious effects reported with tricyclics and SSRIs

Dialogue on 'Institutional complementarity and political economy'

"Martin Höpner's paper was written to structure discussions at a workshop of the 'Complementarity Project', which was held in Paris, 26-27 September 2003. The project was organized by Bruno Amable and Robert Boyer, Colin Crouch, Martin Höpner and Wolfgang Streeck. The subject of the workshop was the complementarity, real or imagined, of financial markets and industrial relations in present-day 'varieties of capitalism'. Apart from the organizers, participants included Patrick Le Gales, Peter Hall, Gregory Jackson, Bruce Kogut, David Marsden and Pascal Petit. In the follwing we document short excerpts from five out of nine 'reaction papers' written by participants in advance of the workshop." (author's abstract

Simulation Cahn-Hilliard/Navier-Stokes du passage d'une bulle à travers une interface liquide-liquide

Cet article présente et exploite un modèle de Cahn-Hilliard/Navier-Stokes triphasique original par la forme particulière de l'énergie libre et des équations d'évolution des paramètres d'ordre. Des propriétés de consistance algébrique et dynamique avec les systèmes diphasiques sous-jacents sont garanties. Les contraintes interfaciales sont représentées par des forces capillaires volumiques qui rendent compte des trois tensions de surface différentes. Le comportement d'une bulle au passage d'une interface liquide-liquide est calculé avec succès : la bulle peut rester piégée dans l'interface ou la traverser, auquel cas elle peut s'en extraire seule ou entraîner dans son sillage une gouttelette de liquide lourd. La dépendance du volume entraîné avec les propriétés des fluides en présence est étudiée. Les résultats obtenus sont en accord avec les observations expérimentales de la littérature

The Virtualization Gate Project

Ercim News 80International audienceThe Vgate project introduces a new type of immersive environment that allows full-body immersion and interaction with virtual worlds. The project is a joint initiative between computer scientists from research teams in computer vision, parallel computing and computer graphics at the INRIA Grenoble Rhone-Alpes, and the 4D View Solutions company

Factors associated with antiretroviral treatment initiation amongst HIV-positive individuals linked to care within a universal test and treat programme: early findings of the ANRS 12249 TasP trial in rural South Africa

Prompt uptake of antiretroviral treatment (ART) is essential to ensure the success of universal test and treat (UTT) strategies to prevent HIV transmission in high-prevalence settings. We describe ART initiation rates and associated factors within an ongoing UTT cluster-randomized trial in rural South Africa. HIV-positive individuals were offered immediate ART in the intervention arm vs. national guidelines recommended initiation (CD4≤350 cells/mm3) in the control arm. We used data collected up to July 2015 among the ART-eligible individuals linked to TasP clinics before January 2015. ART initiation rates at one (M1), three (M3) and six months (M6) from baseline visit were described by cluster and CD4 count strata (cells/mm3) and other eligibility criteria: ≤100; 100–200; 200–350; CD4>350 with WHO stage 3/4 or pregnancy; CD4>350 without WHO stage 3/4 or pregnancy. A Cox model accounting for covariate effect changes over time was used to assess factors associated with ART initiation. The 514 participants had a median [interquartile range] follow-up duration of 1.08 [0.69; 2.07] months until ART initiation or last visit. ART initiation rates at M1 varied substantially (36.9% in the group CD4>350 without WHO stage 3/4 or pregnancy, and 55.2–71.8% in the three groups with CD4≤350) but less at M6 (from 85.3% in the first group to 96.1–98.3% in the three other groups). Factors associated with lower ART initiation at M1 were a higher CD4 count and attending clinics with both high patient load and higher cluster HIV prevalence. After M1, having a regular partner was the only factor associated with higher likelihood of ART initiation. These findings suggest good ART uptake within a UTT setting, even among individuals with high CD4 count. However, inadequate staffing and healthcare professional practices could result in prioritizing ART initiation in patients with the lowest CD4 counts

The brain signature of paracetamol in healthy volunteers: a double-blind randomized trial

International audienceBackground: Paracetamol’s (APAP) mechanism of action suggests the implication of supraspinal structures but no neuroimaging study has been performed in humans.Methods and results: This randomized, double-blind, crossover, placebo-controlled trial in 17 healthy volunteers (NCT01562704) aimed to evaluate how APAP modulates pain-evoked functional magnetic resonance imaging signals. We used behavioral measures and functional magnetic resonance imaging to investigate the response to experimental thermal stimuli with APAP or placebo administration. Region-of-interest analysis revealed that activity in response to noxious stimulation diminished with APAP compared to placebo in prefrontal cortices, insula, thalami, anterior cingulate cortex, and periaqueductal gray matter.Conclusion: These findings suggest an inhibitory effect of APAP on spinothalamic tracts leading to a decreased activation of higher structures, and a top-down influence on descending inhibition. Further binding and connectivity studies are needed to evaluate how APAP modulates pain, especially in the context of repeated administration to patients with pain

Modélisation tri-dimensionnelle temps-réel et distribuée

National audienceCet article traite du problème de la modélisation 3D en temps-réel à partir d'images issues de plusieurs caméras. Les environnements comportant plusieurs caméras et PC deviennent de plus en plus courants, principalement grâce aux nouvelles technologies des caméras et aux très hautes performances des PC modernes. Cependant la plupart des applications de vision par ordinateur n'utilisent qu'un seul ou un petit nombre de PC et passent mal à l'échelle. La motivation de cet article est donc de proposer un cadre distribué permettant d'obtenir des modèles 3D précis en temps-réel avec un nombre variable de caméras, ceci via une utilisation optimisée de l'ensemble des machines disponibles. Nous nous intéressons particulièrement dans cet article aux méthodes calculant l'enveloppe visuelle à partir des silhouettes et la manière de distribuer leurs calculs sur un ensemble de PC. Notre contribution consiste en une stratégie de distribution s'appliquant à différentes méthodes de ce domaine et permettant de concevoir des applications temps-réel. Cette stratégie repose sur différents niveaux de parallélisation, de la répartition de tâches indépendantes à l'exécution concurrente permettant un contrôle précis à la fois sur la latence et le débit du système de modélisation. Nous détaillons aussi l'implémentation d'une telle stratégie pour des applications de modélisation d'enveloppes visuelles. En particulier, nous montrons que des modèles surfaciques précis peuvent être calculés en temps-réel avec uniquement du matériel standard. Nous donnons aussi des résultats sur des données de synthèse et en conditions réelles