What we use is not what we know: environmental predictors in plant distribution models

Questions: The choice of environmental predictor variables in correlative models of plant species distributions (hereafter plant SDMs) is crucial to ensure predictive accuracy and model realism, as highlighted in multiple earlier studies. Because variable selection is directly related to a model's capacity to capture important species' environmental requirements, one would expect an explicit prior consideration of all ecophysiologically meaningful variables. For plants, these include temperature, water, soil nutrients, light, and in some cases, disturbances and biotic interactions. However, the set of predictors used in published correlative plant SDM studies varies considerably. No comprehensive review exists of what environmental predictors are meaningful, available (or missing), and used in practice to predict plant distributions. Contributing to answer these questions is the aim of this review. Methods: We carried out an extensive, systematic review of recently published plant SDM studies (years 2010-2015; n = 200) to determine the predictors used in the models. We additionally conducted an in-depth review of SDM studies in selected journals to identify temporal trends in the use of predictors (years 2000-2015; n = 40). Results: Except for the pure climatic studies, a large majority of plant SDM studies neglected several ecophysiologically-meaningful environmental variables, and the number of relevant predictors used in models has stagnated or even declined over the last 15 years. Conclusions: Neglecting ecophysiologically meaningful predictors can result in incomplete niche quantification and can thus limit the predictive power of plant SDMs. Some of these missing predictors are already available spatially or may soon become available (e.g., soil moisture). However, others are not yet easily obtainable across whole study extents (e.g., soil pH and nutrients), and their development should receive increased attention. We conclude that more effort should be made to build ecologically more sound plant SDMs. This requires a more thorough rationale for the choice of environmental predictors needed to meet the study goal, and the development of missing ones. The latter calls for increased collaborative effort between ecological and geo-environmental science

Magmatic plumbing at Lucky Strike volcano based on olivine-hosted melt inclusion compositions

Author Posting. © American Geophysical Union, 2015. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geochemistry, Geophysics, Geosystems 16 (2015): 126–147, doi:10.1002/2014GC005517.Here we present volatile, major, and trace element concentrations of 64 olivine-hosted melt inclusions from the Lucky Strike segment on the mid-Atlantic ridge. Lucky Strike is one of two locations where a crustal melt lens has been seismically imaged on a slow-spreading ridge. Vapor-saturation pressures, calculated from CO2 and H2O contents of Lucky Strike melt inclusions, range from approximately 300–3000 bars, corresponding to depths of 0.5–9.9 km below the seafloor. Approximately 50% of the melt inclusions record crystallization depths of 3–4 km, corresponding to the seismically imaged melt lens depth, while an additional ∼35% crystallize at depths > 4 km. This indicates that while crystallization is focused within the melt lens, significant crystallization also occurs in the lower crust and/or upper mantle. The melt inclusions span a range of major and trace element concentrations from normal to enriched basalts. Trace element ratios at all depths are heterogeneous, suggesting that melts are not efficiently homogenized in the mantle or crust, despite the presence of a melt lens. This is consistent with the transient nature of magma chambers proposed for slower-spreading ridges. To investigate the petrogenesis of the melt inclusion compositions, we compare the measured trace element compositions to theoretical melting calculations that consider variations in the melting geometry and heterogeneities in the mantle source. The full range of compositions can be produced by slight variations in the proportion of an Azores plume and depleted upper mantle components and changes in the total extent of melting.thanked for his help with sample preparation. The GRAVILUCK'06 and Bathyluck'08 cruises where financed by the French Ministry of Research. This work was supported by NSF grant OCE-0926422 to A.M.S., OCE-PRF-1226130 to V.D.W., OCE-1333492 to S.A.S., and EAR-09-48666 to M.D.B., and by ANR (France) Mothseim Project NT05-342213 to J.E.2015-07-2

Extracorporeal Membrane Oxygenation for Severe Acute Respiratory Distress Syndrome associated with COVID-19: An Emulated Target Trial Analysis.

RATIONALE: Whether COVID patients may benefit from extracorporeal membrane oxygenation (ECMO) compared with conventional invasive mechanical ventilation (IMV) remains unknown. OBJECTIVES: To estimate the effect of ECMO on 90-Day mortality vs IMV only Methods: Among 4,244 critically ill adult patients with COVID-19 included in a multicenter cohort study, we emulated a target trial comparing the treatment strategies of initiating ECMO vs. no ECMO within 7 days of IMV in patients with severe acute respiratory distress syndrome (PaO2/FiO2 <80 or PaCO2 ≥60 mmHg). We controlled for confounding using a multivariable Cox model based on predefined variables. MAIN RESULTS: 1,235 patients met the full eligibility criteria for the emulated trial, among whom 164 patients initiated ECMO. The ECMO strategy had a higher survival probability at Day-7 from the onset of eligibility criteria (87% vs 83%, risk difference: 4%, 95% CI 0;9%) which decreased during follow-up (survival at Day-90: 63% vs 65%, risk difference: -2%, 95% CI -10;5%). However, ECMO was associated with higher survival when performed in high-volume ECMO centers or in regions where a specific ECMO network organization was set up to handle high demand, and when initiated within the first 4 days of MV and in profoundly hypoxemic patients. CONCLUSIONS: In an emulated trial based on a nationwide COVID-19 cohort, we found differential survival over time of an ECMO compared with a no-ECMO strategy. However, ECMO was consistently associated with better outcomes when performed in high-volume centers and in regions with ECMO capacities specifically organized to handle high demand. This article is open access and distributed under the terms of the Creative Commons Attribution Non-Commercial No Derivatives License 4.0 (http://creativecommons.org/licenses/by-nc-nd/4.0/)

A flexible polymer–nanoparticle hybrid material containing triazole-based Fe( ii ) with spin crossover properties for magneto-optical applications

International audienceIn the perspective of elaborating functional devices based on inorganic molecular materials, it is important not only to continue research on their synthesis and to understand their properties but also to develop new strategies for their processing and shaping. In this context, we show here that centimeter-scale materials exhibiting solid state-like spin-crossover (SCO) properties and easy handling under ambient conditions can be obtained that preserve their thermochromic properties over months. Combining a tri-azole-based Fe(II) SCO compound with functionalized silica nanoparticles gives rise to nanocomposite soft gels. These gels were used as templates for the formation of a flexible macroporous hybrid silica network via a vapor phase sol-gel process. Further coating with PDMS provided both long-term protection of the material against drying and operationality in aqueous media. Our approach offers new hopes for the development of optical and magnetic devices based on SCO coordination polymers

Scattering by a Thin Slab: Comparison Between Radiative Transfer and Electromagnetic Simulation

International audienceThe paper is devoted to the study of scattering of waves by a slab containing randomly located cylinders. For the first time, the complete transmission problem has been solved numerically. We have compared the radiative transfer theory with a numerical solution of the wave equation. We discuss the coherent effects such as forward scattering dip and backscattering enhancement. It is seen that the radiative transfer equation can be used with great accuracy even for optically thick systems whose geometric thickness is comparable to the wavelength. We have also shown the presence of dependent scattering

Scattering by a slab containing randomly located cylinders: comparison between radiative transfer and electromagnetic simulation

International audienceThis study is devoted to the examination of scattering of waves by a slab containing randomly located cylinders. For the first time to our knowledge, the complete transmission problem has been solved numerically. We have compared the radiative transfer theory with a numerical solution of the wave equation. We discuss the coherent effects, such as forward-scattering dip and backscattering enhancement. It is seen that the ra-diative transfer equation can be used with great accuracy even for optically thin systems whose geometric thickness is comparable with the wavelength. We have also shown the presence of dependent scattering

Functional erythropoietin‐hepcidin axis in recombinant human erythropoietin independent haemodialysis patients

International audienceRelatively few haemodialysis (HD) patients remain independent of recombinant human erythropoietin ('rHU-EPO free patients'). We investigated the role of EPO and hepcidin, two key hormones involved in anaemia

Bacteria encapsulation in a magnetic sol-gel matrix

The encapsulation of Escherichia coli bacteria within ferrihydrite gels favours the long-term viability of the entrapped cells while preserving the magnetic properties of the host material.Fil: Amoura, Makhlouf. Universite de Paris VI; FranciaFil: Brayner, Roberta. Université Paris Diderot - Paris 7; FranciaFil: Perullini, Ana Mercedes. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; ArgentinaFil: Sicard, Clémence. Universite de Paris VI; Francia. Université Paris Diderot - Paris 7; FranciaFil: Roux, Cécile. Universite de Paris VI; FranciaFil: Livage, Jacques. Universite de Paris VI; FranciaFil: Coradin, Thibaud. Universite de Paris VI; Franci