Field evidence of swash groundwater circulation in the microtidal rousty beach, France

International audienceThis manuscript reports on a novel field experiment carried out on a microtidal beach in Camargue, France. For the first time in the field, a comprehensive description of the groundwater dynamics under sandy beach swash zone is presented. A cross-shore network of 15 buried pressure sensors is combined with terrestrial LiDAR measurements to study the swash-groundwater dynamics. The presented data focus on the decay of a moderate storm which allows to monitor the evolution of the groundwater pressure field in response to the retreat of the swash zone. Both horizontal and vertical head gradients are measured within the porous sand soil to estimate the groundwater flow field using Darcy’s law. Time-averaged analysis demonstrates the presence of a rather consistent groundwater circulation pattern under the swash zone, shifting offshore with the swash zone. The main tendency is an offshore directed flow, with infiltration/exfiltration in the upper/lower parts of the swash zone. Time-resolved analysis highlights the typical groundwater response to swash events which consists mainly of an overall infiltration flow during the bed inundation by the swash tongue, a seaward flow during the swash retreat and, for long backwash events, a localized exfiltration flow under the next incoming uprush

RENEB accident simulation exercise

Purpose: The RENEB accident exercise was carried out in order to train the RENEB participants in coordinating and managing potentially large data sets that would be generated in case of a major radiological event. Materials and methods: Each participant was offered the possibility to activate the network by sending an alerting email about a simulated radiation emergency. The same participant had to collect, compile and report capacity, triage categorization and exposure scenario results obtained from all other participants. The exercise was performed over 27 weeks and involved the network consisting of 28 institutes: 21 RENEB members, four candidates and three non-RENEB partners. Results: The duration of a single exercise never exceeded 10 days, while the response from the assisting laboratories never came later than within half a day. During each week of the exercise, around 4500 samples were reported by all service laboratories (SL) to be examined and 54 scenarios were coherently estimated by all laboratories (the standard deviation from the mean of all SL answers for a given scenario category and a set of data was not larger than 3 patient codes). Conclusions: Each participant received training in both the role of a reference laboratory (activating the network) and of a service laboratory (responding to an activation request). The procedures in the case of radiological event were successfully established and tested

Redundant Mechanisms for Regulation of Midline Crossing in Drosophila

During development, all neurons have to decide on whether to cross the longitudinal midline to project on the contralateral side of the body. In vertebrates and invertebrates regulation of crossing is achieved by interfering with Robo signalling either through sorting and degradation of the receptor, in flies, or through silencing of its repulsive activity, in vertebrates. Here I show that in Drosophila a second mechanism of regulation exists that is independent from sorting. Using in vitro and in vivo assays I mapped the region of Robo that is sufficient and required for its interaction with Comm, its sorting receptor. By modifying that region, I generated new forms of Robo that are insensitive to Comm sorting in vitro and in vivo, yet still able to normally translate repulsive activity in vivo. Using gene targeting by homologous recombination I created new conditional alleles of robo that are sorting defective (roboSD). Surprisingly, expression of these modified proteins results in phenotypically normal flies, unveiling a sorting independent mechanism of regulation

Consistent patterns of common species across tropical tree communities

Trees structure the Earth’s most biodiverse ecosystem, tropical forests. The vast number of tree species presents a formidable challenge to understanding these forests, including their response to environmental change, as very little is known about most tropical tree species. A focus on the common species may circumvent this challenge. Here we investigate abundance patterns of common tree species using inventory data on 1,003,805 trees with trunk diameters of at least 10 cm across 1,568 locations1,2,3,4,5,6 in closed-canopy, structurally intact old-growth tropical forests in Africa, Amazonia and Southeast Asia. We estimate that 2.2%, 2.2% and 2.3% of species comprise 50% of the tropical trees in these regions, respectively. Extrapolating across all closed-canopy tropical forests, we estimate that just 1,053 species comprise half of Earth’s 800 billion tropical trees with trunk diameters of at least 10 cm. Despite differing biogeographic, climatic and anthropogenic histories7, we find notably consistent patterns of common species and species abundance distributions across the continents. This suggests that fundamental mechanisms of tree community assembly may apply to all tropical forests. Resampling analyses show that the most common species are likely to belong to a manageable list of known species, enabling targeted efforts to understand their ecology. Although they do not detract from the importance of rare species, our results open new opportunities to understand the world’s most diverse forests, including modelling their response to environmental change, by focusing on the common species that constitute the majority of their trees.Publisher PDFPeer reviewe

Omecamtiv mecarbil in chronic heart failure with reduced ejection fraction, GALACTIC‐HF: baseline characteristics and comparison with contemporary clinical trials

Aims: The safety and efficacy of the novel selective cardiac myosin activator, omecamtiv mecarbil, in patients with heart failure with reduced ejection fraction (HFrEF) is tested in the Global Approach to Lowering Adverse Cardiac outcomes Through Improving Contractility in Heart Failure (GALACTIC‐HF) trial. Here we describe the baseline characteristics of participants in GALACTIC‐HF and how these compare with other contemporary trials. Methods and Results: Adults with established HFrEF, New York Heart Association functional class (NYHA) ≥ II, EF ≤35%, elevated natriuretic peptides and either current hospitalization for HF or history of hospitalization/ emergency department visit for HF within a year were randomized to either placebo or omecamtiv mecarbil (pharmacokinetic‐guided dosing: 25, 37.5 or 50 mg bid). 8256 patients [male (79%), non‐white (22%), mean age 65 years] were enrolled with a mean EF 27%, ischemic etiology in 54%, NYHA II 53% and III/IV 47%, and median NT‐proBNP 1971 pg/mL. HF therapies at baseline were among the most effectively employed in contemporary HF trials. GALACTIC‐HF randomized patients representative of recent HF registries and trials with substantial numbers of patients also having characteristics understudied in previous trials including more from North America (n = 1386), enrolled as inpatients (n = 2084), systolic blood pressure < 100 mmHg (n = 1127), estimated glomerular filtration rate < 30 mL/min/1.73 m2 (n = 528), and treated with sacubitril‐valsartan at baseline (n = 1594). Conclusions: GALACTIC‐HF enrolled a well‐treated, high‐risk population from both inpatient and outpatient settings, which will provide a definitive evaluation of the efficacy and safety of this novel therapy, as well as informing its potential future implementation

Artificial pebbles nourhisment on microtidal sandy beaches

International audienceArtificial beach nourishment has become a common practice in coastal engineering. On sandy beaches, initiatives are emerging concerning pebble nourishment. Indeed, by increasing the granulometry, coastal managers hope to reduce shoreline recession more significantly than what would have been achieved by artificial sand nourishment.In this presentation we estimate the effectiveness and impact of artificial pebble nourishment on two microtidal beaches along the French Mediterranean coastline: (1) exposed to wave in Camargue (annual Hsig = 3.5m) and (2) subjected to low wave (annual Hisg < 2.0m) along the shoreline of the Etang de Berre. In both cases the beach has been recharged in order to widen it. On the beach exposed to waves, the nourishment did not significantly slow the retreat of the shoreline, whereas it succeeded in stabilizing it on the less exposed beach. In the Camargue, pebble deposits reworked by waves take the form of overwash. In both cases, the pebbles are subject to the dominant longshore littoral drift which exports the pebbles outside the nourished zone. We do not observe any significant morphological evolution of the surf zone, although we would expect an increase in slope in relation to the morphology that has become rather reflective in the swash zone. The pebbles remain on the foreshore and beach without moving offshore

Chronic offshore loss of nourishment on Nice beach, French Riviera: A case of over-nourishment of a steep beach?

International audienceThe 4.5 km-long gravel beach fronting the exclusive resort of the city of Nice, on the French Riviera, insoutheastern France, was artificially nourished from 1976 to 2005 to the tune of 558,000 m3, making thislong-term operation one of the most significant for gravel beaches in the world. Nourishment has ranged fromnil in certain years (1979, 1980, 1983–85, and 2001–2002) to a peak of over 97,000 m3 in 2000. Analyses of 50transects covering the beach highlight no significant change in net beach width over this 30-year period ofmassive gravel nourishment. A Principal Components Analysis and a Cluster Analysis used to detect patternsin the 87 beach-width measurement dataset show no clear spatial trends in transect groups that can beinterpreted in terms of the morphology of the beach and the steep inner shoreface. Significant wave height offNice shows no change over the period 1979–2005. Since there is no possibility for alongshore gravel leakageon the strongly embayed Nice beach, the relative stability in beach width clearly implies loss of rechargedgravel offshore. Gravel loss following nourishment is favoured by: (1) the steep inner shoreface inheritedfrom the geological context of Nice beach at the flanks of the southern Alps, and (2) the practise of artificialbeach widening through flattening, in summer, of a narrow (5–15 m-wide) mobile zone of the profile in orderto enhance the ‘carrying’ capacity of this highly touristic beach. Beach widening and flattening followingnourishment bring close to the very steep inner shoreface zone several cubic metres of gravel for each metreof beach that may be permanently lost downslope during autumn and winter storms. Recharged gravel isredistributed alongshore and offshore leakage is probably enhanced where small narrow submarine canyonheads impinge on the beach, resulting in a very narrow shoreface. Mean beach width shows an oscillatingalongshore pattern that may be due to the influence of these canyons as pathways of gravel loss offshore.However, there is no correlation between mean beach width and distance to the 10-m isobath, used as asurrogate for inner shoreface width. Storms are associated with plunging waves that are particularly effectiveand concentrated, on this almost tideless shore, over the narrow mobile zone of the beach profile where aseries of steep reflective berms are built during storms. The high dynamic pressures associated with thisnarrow zone of concentrated wave breaking, and energy reflection from the steepened profile, are deemed tocontribute to the permanent downslope loss of gravel. This situation of long-term gravel loss is probablyaccepted by the beach management authority because of the low cost of obtaining nourishment material andthe advantages derived from a temporarily wider beach in terms of recreational space

Estimation of the number of tree species in French Guiana by extropolation of permanent plots richness

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