Evidence of multi-phase Cretaceous to Quaternary alkaline magmatism on Tore-Madeira Rise and neighbouring seamounts from 40Ar/39Ar ages.

The Tore-Madeira Rise is a seamount chain located 300 km off the Portugal and Morocco coastsattributed to hotspot activity. U-Pb ages of lavas from the northern and central Tore-Madeira Rise rangebetween 103 and 80.5 Ma whereas 40Ar/39Ar ages from the central and southern Tore-Madeira Rise yield ages ranging from 94.5 to 0.5 Ma. We performed new 40Ar/39Ar measurements to better understand the geodynamic history of the Tore-Madeira Rise. Plagioclase ages from the Bikini Bottom and Torillon seamounts suggest ages of .90 Ma and >60 Ma, respectively. Amphiboles from the Seine seamount yield an age of 24.0 +- 0.8 Ma. Biotites from lavas of the Ashton seamount give ages of 97.4 +- 1.1 Ma and 97.8 +- 1.1 Ma. The geochronological database available on the Tore-Madeira Rise has been filtered on statistical criteria to eliminate unreliable ages. The resulting database reveals three pulses of alkaline magmatism on the Tore-Madeira Rise at 103-80.5 Ma, at c. 68 Ma and between 30 Ma and the present. The magmatism was continuous from 103 Ma until c. 68 Ma and from c. 30 Ma until the present on the Tore-Madeira Rise, the surrounding seamounts and the Portugal coast. We suggest that the space-time distribution of this magmatism results from the interaction between a wide thermal anomaly emitting magmatic pulses and the complex motion of the Iberian plate

Theory of superfluidity and drag force in the one-dimensional Bose gas

The one-dimensional Bose gas is an unusual superfluid. In contrast to higher spatial dimensions, the existence of non-classical rotational inertia is not directly linked to the dissipationless motion of infinitesimal impurities. Recently, experimental tests with ultracold atoms have begun and quantitative predictions for the drag force experienced by moving obstacles have become available. This topical review discusses the drag force obtained from linear response theory in relation to Landau's criterion of superfluidity. Based upon improved analytical and numerical understanding of the dynamical structure factor, results for different obstacle potentials are obtained, including single impurities, optical lattices and random potentials generated from speckle patterns. The dynamical breakdown of superfluidity in random potentials is discussed in relation to Anderson localization and the predicted superfluid-insulator transition in these systems.Comment: 17 pages, 12 figures, mini-review prepared for the special issue of Frontiers of Physics "Recent Progresses on Quantum Dynamics of Ultracold Atoms and Future Quantum Technologies", edited by Profs. Lee, Ueda, and Drummon

Coincident beach surveys using UAS, vehicle mounted and airborne laser scanner: point cloud inter-comparison and effects of surface type heterogeneity on elevation accuracies

Reliable and consistent topographic data is key to a multitude of environmental manangement and research applications. Unmanned Aerial Systems (UAS) are fast establishing themselves as a promising additional remote sensing platform that provides high spatial resolution not only of topography but also surface types and coastal features together with comparatively low costs and high deployment flexibility. However, comprehensive information on the accuracy of UAS-based elevation models in comparison to other available surveying methodology is regulary limited to be referenced to individual methods. This paper addresses this shortcoming by comparing coincident beach surveys of three different point cloud generating methods: ATV mounted mobile laser scan (MLS), airborne LiDAR (ALS), and UAS. This was complemented by two RTK-GPS surveys on a pole with wheel attachment and mounted on an ATV. We present results in relation to elevation accuracies on a concrete control surface, the entire beach and for six different beach surface types together with how differences between point clouds propagate during the construction of gridded elevation models. Overall, UAS point cloud elevations were consistently higher than those of ALS (+0.063 m) and MLS (+0.087 m). However, these results for the entire beach mask larger and smaller differences related to the individual surface characteristics. For all surface types, UAS records higher (from 0.006 m for wet sand to 0.118 m for cobbles, average of 0.063 m) elevations than ALS. The MLS on the other hand, records predominantly lower elevation than ALS (-0.005 m for beach gravel to -0.089 m for soft mud, average of -0.025 m) except for cobbles, where elevations are 0.056 m higher. The comparison shows that all point cloud methods produce elevations that are suitable for monitoring changes in beach topography in the context of operational coastal management applications. However, due to the systematic differences between respective monitoring approaches, care needs to be taken when analysing beach topographies for the same area based on different methods. The eventual choice of monitoring method is therefore guided by a range of practical factors, including capital cost of the system and operating costs per survey area, conditions under which the system can operate, data processing time, and legal restrictions in the use of the system such as air safety regulations or limitation of ground access to areas with environmental protection

Finding the engram.

Many attempts have been made to localize the physical trace of a memory, or engram, in the brain. However, until recently, engrams have remained largely elusive. In this Review, we develop four defining criteria that enable us to critically assess the recent progress that has been made towards finding the engram. Recent \u27capture\u27 studies use novel approaches to tag populations of neurons that are active during memory encoding, thereby allowing these engram-associated neurons to be manipulated at later times. We propose that findings from these capture studies represent considerable progress in allowing us to observe, erase and express the engram

Efficient three-dimensional reconstruction of aquatic vegetation geometry: Estimating morphological parameters influencing hydrodynamic drag

Aquatic vegetation can shelter coastlines from energetic waves and tidal currents, sometimes enabling accretion of fine sediments. Simulation of flow and sediment transport within submerged canopies requires quantification of vegetation geometry. However, field surveys used to determine vegetation geometry can be limited by the time required to obtain conventional caliper and ruler measurements. Building on recent progress in photogrammetry and computer vision, we present a method for reconstructing three-dimensional canopy geometry. The method was used to survey a dense canopy of aerial mangrove roots, called pneumatophores, in Vietnam’s Mekong River Delta. Photogrammetric estimation of geometry required 1) taking numerous photographs at low tide from multiple viewpoints around 1 m2 quadrats, 2) computing relative camera locations and orientations by triangulation of key features present in multiple images and reconstructing a dense 3D point cloud, and 3) extracting pneumatophore locations and diameters from the point cloud data. Step 3) was accomplished by a new ‘sector-slice’ algorithm, yielding geometric parameters every 5 mm along a vertical profile. Photogrammetric analysis was compared with manual caliper measurements. In all 5 quadrats considered, agreement was found between manual and photogrammetric estimates of stem number, and of number × mean diameter, which is a key parameter appearing in hydrodynamic models. In two quadrats, pneumatophores were encrusted with numerous barnacles, generating a complex geometry not resolved by hand measurements. In remaining cases, moderate agreement between manual and photogrammetric estimates of stem diameter and solid volume fraction was found. By substantially reducing measurement time in the field while capturing in greater detail the 3D structure, photogrammetry has potential to improve input to hydrodynamic models, particularly for simulations of flow through large-scale, heterogenous canopies

Validation of a relapse prevention strategy based on the extinction of the conditioned incentive effects of cocaine

L’addiction aux drogues d’abus se caractérise par une prise compulsive de drogue et par des épisodes récurrents de rechute après abstinence. Ces épisodes de rechute, parfois mortels, sont généralement précédés par un désir intense et irrépressible pour la drogue, appelé aussi craving. Bien que le rôle causal du craving dans la rechute reste encore à démontrer, la prévention du craving est devenue récemment un enjeu important des recherches clinique et préclinique. Chez l’homme l’amorçage du craving s’effectue après exposition ou réexposition à la drogue elle-même, à un stress, ou à des stimuli conditionnés à la prise de drogue. Chez l’animal, cet amorçage peut être modélisé par la reprise du comportement de recherche de drogue après arrêt du renforcement. Cette reprise peut être amorcée par les mêmes facteurs amorçant le craving chez l’homme, notamment par la réexposition à la drogue elle-même, ce qui suggère qu’elle exprime un état ressemblant au craving. Selon une hypothèse récente, l’amorçage du craving par la drogue serait dû à un conditionnement intéroceptif. Ce conditionnement se formerait au cours de l’acquisition où les animaux apprendraient à associer les stimuli intéroceptifs périphériques de la drogue avec la disponibilité du renforcement. Après arrêt du renforcement, la réexposition à ces stimuli intéroceptifs conditionnés provoquerait la reprise de la recherche de drogue en signalant (faussement) aux animaux le retour du renforcement. Cette hypothèse a permis le développement et la validation récente d’une stratégie anti-craving basée sur l’extinction de ces stimuli conditionnés de la cocaïne. Dans ce contexte, mon travail de thèse a eu pour but principal d’évaluer l’efficacité potentielle de cette stratégie à prévenir la rechute proprement dite, c’est-à-dire le retour aux niveaux de prise de cocaïne avant l’extinction. Ce travail a permis de démontrer : 1) qu’il est possible d’éteindre complètement l’amorçage du craving par la cocaïne chez l’animal ; 2) que cette extinction est accompagnée par une perte des réponses neuronales à la cocaïne dans les régions du cerveau causalement impliquées dans l’amorçage du craving (i.e., cortex préfrontal prélimbique et partie « core » du noyau accumbens); 3) mais que malgré nos attentes initiales, l’extinction complète et prolongée de l’amorçage du craving par la cocaïne n’a aucun effet préventif majeur sur la rechute, suggérant une dissociation entre craving et rechute, du moins chez l’animal ; enfin, 4) que cet échec relatif est dû en grande partie à l’existence d’une forme résiduelle de recherche de cocaïne résistante à l’extinction, fréquemment rapportée dans la littérature mais généralement ignorée. Cibler cette résistance à l’extinction afin de l’éradiquer devrait représenter un enjeu majeur pour la recherche future dans le domaine.Craving often precedes relapse into cocaine addiction. This explains why considerable research effort is being expended to try to develop anti-craving strategies for relapse prevention. Recently, we discovered using the classic reinstatement model of cocaine craving that the reinstating or priming effect of cocaine can be extinguished with repeated priming – a phenomenon dubbed extinction of cocaine priming. Such extinction has been interpreted as evidence that the priming effect of cocaine on reinstatement of cocaine seeking depends on an interoceptive drug conditioning mechanism whereby the interoceptive cues of cocaine become reliable conditioned Pavlovian predictors of the availability of cocaine reinforcement. Regardless of the underlying mechanisms, however, extinction of drug priming has been proposed as a potential cocaine exposure therapy for relapse prevention that may complement other, more traditional exteroceptive cue exposure therapies. The goal of my PhD thesis was to measure the potential beneficial effect of this novel extinction strategy on subsequent relapse (i.e., return to the pre-extinction pattern of cocaine self-administration once the drug is made again available after extinction). Overall and contrary to our initial hope, extensive and complete extinction of cocaine priming had no major impact on relapse. This lack of effect occurred despite evidence for post-extinction loss of neuronal responsiveness to cocaine priming in brain regions causally involved in cocaine-induced reinstatement (i.e., the anterior cingulate and prelimbic prefrontal cortex, and the core of the nucleus accumbens). An effect of extinction of cocaine priming on relapse was only observed when cocaine was available for self-administration under more demanding conditions. However, this effect was modest and short-lived. Finally, we were able to trace the origin of our failure to prevent relapse to an extinction-resistant form of cocaine seeking that is commonly reported, though often overlooked, in other reinstatement studies. We propose that this behavior should become a novel target for future preclinical research on anti-craving strategies for relapse prevention

Validation d’une stratégie de prévention de la rechute basée sur l’extinction des effets incitatifs de la cocaïne

Craving often precedes relapse into cocaine addiction. This explains why considerable research effort is being expended to try to develop anti-craving strategies for relapse prevention. Recently, we discovered using the classic reinstatement model of cocaine craving that the reinstating or priming effect of cocaine can be extinguished with repeated priming – a phenomenon dubbed extinction of cocaine priming. Such extinction has been interpreted as evidence that the priming effect of cocaine on reinstatement of cocaine seeking depends on an interoceptive drug conditioning mechanism whereby the interoceptive cues of cocaine become reliable conditioned Pavlovian predictors of the availability of cocaine reinforcement. Regardless of the underlying mechanisms, however, extinction of drug priming has been proposed as a potential cocaine exposure therapy for relapse prevention that may complement other, more traditional exteroceptive cue exposure therapies. The goal of my PhD thesis was to measure the potential beneficial effect of this novel extinction strategy on subsequent relapse (i.e., return to the pre-extinction pattern of cocaine self-administration once the drug is made again available after extinction). Overall and contrary to our initial hope, extensive and complete extinction of cocaine priming had no major impact on relapse. This lack of effect occurred despite evidence for post-extinction loss of neuronal responsiveness to cocaine priming in brain regions causally involved in cocaine-induced reinstatement (i.e., the anterior cingulate and prelimbic prefrontal cortex, and the core of the nucleus accumbens). An effect of extinction of cocaine priming on relapse was only observed when cocaine was available for self-administration under more demanding conditions. However, this effect was modest and short-lived. Finally, we were able to trace the origin of our failure to prevent relapse to an extinction-resistant form of cocaine seeking that is commonly reported, though often overlooked, in other reinstatement studies. We propose that this behavior should become a novel target for future preclinical research on anti-craving strategies for relapse prevention.L’addiction aux drogues d’abus se caractérise par une prise compulsive de drogue et par des épisodes récurrents de rechute après abstinence. Ces épisodes de rechute, parfois mortels, sont généralement précédés par un désir intense et irrépressible pour la drogue, appelé aussi craving. Bien que le rôle causal du craving dans la rechute reste encore à démontrer, la prévention du craving est devenue récemment un enjeu important des recherches clinique et préclinique. Chez l’homme l’amorçage du craving s’effectue après exposition ou réexposition à la drogue elle-même, à un stress, ou à des stimuli conditionnés à la prise de drogue. Chez l’animal, cet amorçage peut être modélisé par la reprise du comportement de recherche de drogue après arrêt du renforcement. Cette reprise peut être amorcée par les mêmes facteurs amorçant le craving chez l’homme, notamment par la réexposition à la drogue elle-même, ce qui suggère qu’elle exprime un état ressemblant au craving. Selon une hypothèse récente, l’amorçage du craving par la drogue serait dû à un conditionnement intéroceptif. Ce conditionnement se formerait au cours de l’acquisition où les animaux apprendraient à associer les stimuli intéroceptifs périphériques de la drogue avec la disponibilité du renforcement. Après arrêt du renforcement, la réexposition à ces stimuli intéroceptifs conditionnés provoquerait la reprise de la recherche de drogue en signalant (faussement) aux animaux le retour du renforcement. Cette hypothèse a permis le développement et la validation récente d’une stratégie anti-craving basée sur l’extinction de ces stimuli conditionnés de la cocaïne. Dans ce contexte, mon travail de thèse a eu pour but principal d’évaluer l’efficacité potentielle de cette stratégie à prévenir la rechute proprement dite, c’est-à-dire le retour aux niveaux de prise de cocaïne avant l’extinction. Ce travail a permis de démontrer : 1) qu’il est possible d’éteindre complètement l’amorçage du craving par la cocaïne chez l’animal ; 2) que cette extinction est accompagnée par une perte des réponses neuronales à la cocaïne dans les régions du cerveau causalement impliquées dans l’amorçage du craving (i.e., cortex préfrontal prélimbique et partie « core » du noyau accumbens); 3) mais que malgré nos attentes initiales, l’extinction complète et prolongée de l’amorçage du craving par la cocaïne n’a aucun effet préventif majeur sur la rechute, suggérant une dissociation entre craving et rechute, du moins chez l’animal ; enfin, 4) que cet échec relatif est dû en grande partie à l’existence d’une forme résiduelle de recherche de cocaïne résistante à l’extinction, fréquemment rapportée dans la littérature mais généralement ignorée. Cibler cette résistance à l’extinction afin de l’éradiquer devrait représenter un enjeu majeur pour la recherche future dans le domaine

Stereoselective Synthesis of the Core of Naturally Occurring Anti-HIV Isolitseane B

International audienceA key intermediate in the total synthesis of naturally occurring anti-HIV Isolitseane B has been prepared in five steps from propargyl alcohol, featuring a highly selective mono-transacetalization and a stereoselective Pauson-Khand cyclization

Loss of resistance to punishment of cocaine use after prior experience

One behavioral feature of drug addiction is continued drug use despite awareness that this causes negative consequences. Attempts to model this feature in animals typically involve punishing drug self-administration with a brief electrical footshock and look for resistance to punishment. Though all individual animals eventually stop self-administering the drug with increasing intensity of punishment, some individuals do so at higher intensities than other individuals. The greater relative resistance to punishment of the former individuals is generally interpreted as evidence for a compulsion-like behavior. Here we show that resistance to footshock punishment is in fact not a stable individual behavioral feature. Specifically, when rats are retested for their resistance to increasing intensity of footshock punishment, they become much less resistant. As a result, they suppress their cocaine intake even when punished with an initially low and ineffective intensity. A series of original behavioral experiments reveals that this low resistance to footshock punishment is rapidly acquired after rats experience a punishment intensity that leads them to near-completely suppress their cocaine intake. Passive exposure to the same intensity does not induce this effect. Once acquired, low resistance to punishment persists during at least one month, but can nevertheless be extinguished by retesting rats on a daily basis. Interestingly, this acquired low resistance to footshock punishment does not generalize to a non-painful form of punishment (i.e., histamine) that is also seldom used in animal drug self-administration studies. We discuss some possible theoretical and methodological implications of these findings for future research on animal models of compulsion-like behavior

Increased responsiveness to punishment of cocaine self-administration after experience with high punishment.

International audienceOne behavioral feature of drug addiction is continued drug use despite awareness that this causes negative consequences. Attempts to model this feature in animals typically involve punishing drug self-administration with electrical footshock to identify individuals whose drug use is differently suppressed by punishment. Here we sought to further study individual responsiveness of drug use to punishment in rats self-administering intravenous cocaine. Rats were first trained during several weeks to self-administer cocaine under a fixed-ratio 3 schedule of reinforcement. Then, their self-administration behavior was punished with increasing intensity of footshock (i.e., from 0.1 mA to 0.9 mA, every 30 min). With increasing intensity of punishment, rats first continued to self-administer cocaine before eventually stopping near completely. When retested, however, drug use became more responsive to punishment and was suppressed by a low and initially ineffective footshock intensity (i.e., 0.1 mA). This increase in responsiveness to punishment was seen in all individuals tested, albeit with varying degrees, and was acquired after one single experience with an intensity of punishment that near completely suppressed drug self-administration. Mere passive, non-contingent exposure to the same intensity, however, had no such effect. Once acquired, increased responsiveness to punishment persisted during at least one month when rats were tested every week, but not every day. Finally, increased responsiveness to punishment was not observed after exposure to a non-painful form of punishment (i.e., histamine). Overall, this study reveals that initial responsiveness of drug use to punishment can change rapidly and persistently with experience. We discuss several possible mechanisms that may account for this change in punishment responsiveness and also draw some of the implications and future perspectives for research on animal models of compulsion-like behavior