Comparison of corneal endothelial mosaic according to the age: the corimmo 3D project

International audienceAim: The human corneal endothelium is a monolayer of flat hexagonal cells. It is a nearly regular hexagonal tessellation during the first years of life, but with age, becomes less regular in shape and size. The aim is to evaluate geometrically the age of an endothelial mosaic.Material and methods: Segmented endothelial mosaics of healthy subjects of different age groups are compared by morphological criteria. The mosaics are studied according to their age group (decades), their age and their location (center or mid-periphery of the cornea). The measures used are: the cell density, the Ripley's L function and the cell area and perimeter density.Results: These measures point out the endothelial cell density decrease, the cell area, perimeter and diameter increase, the cell heterogeneity increase, and the differences between central and mid-peripheral cells increases with age.Conclusion: These measures are able to characterize healthy mosaics

Modelling the porewater chemistry of the Callovian–Oxfordian formation at a regional scale

International audienceIn ANDRA's studies to characterize the Callovian-Oxfordian formation, porewater chemistry is a key topic. Indeed, chemistry determines the durability of the repository materials (bentonite, concrete, metals, nuclear glass) and the speciation (and thus the mobility) of radionuclides. The method developed in the frame of the THERMOAR project enables the acquisition of a complete set of data from core samples to model the porewater chemistry. The method requires a detailed mineralogical study, a model of free-water/bound-water distribution, leaching experiments, adsorbed ion measurements, ion-exchange constant acquisition, and CO2 partial-pressure measurements. These experiments and measurements were done on samples from the site of the Meuse/Haute-Marne laboratory and from ANDRA's regional boreholes. The regional stability of a great number of parameters can be observed, except for a decrease of the Na and Cl concentration following a NE-SW axis passing through the laboratory. The water/rock equilibrium model makes it possible to calculate the chemical composition of interstitial waters of the formation

Transit timings variations in the three-planet system: TOI-270

We present ground- and space-based photometric observations of TOI-270 (L231-32), a system of three transiting planets consisting of one super-Earth and two sub-Neptunes discovered by TESS around a bright (K-mag = 8.25) M3V dwarf. The planets orbit near low-order mean-motion resonances (5:3 and 2:1) and are thus expected to exhibit large transit timing variations (TTVs). Following an extensive observing campaign using eight different observatories between 2018 and 2020, we now report a clear detection of TTVs for planets c and d, with amplitudes of ∼10 min and a super-period of ∼3 yr, as well as significantly refined estimates of the radii and mean orbital periods of all three planets. Dynamical modelling of the TTVs alone puts strong constraints on the mass ratio of planets c and d and on their eccentricities. When incorporating recently published constraints from radial velocity observations, we obtain masses of Mb=1.48± 0.18, M⊕, Mc=6.20± 0.31, M⊕, and Md=4.20± 0.16, M⊕ for planets b, c, and d, respectively. We also detect small but significant eccentricities for all three planets: eb = 0.0167 ± 0.0084, ec = 0.0044 ± 0.0006, and ed = 0.0066 ± 0.0020. Our findings imply an Earth-like rocky composition for the inner planet, and Earth-like cores with an additional He/H2O atmosphere for the outer two. TOI-270 is now one of the best constrained systems of small transiting planets, and it remains an excellent target for atmospheric characterization

Enabling planetary science across light-years. Ariel Definition Study Report

Ariel, the Atmospheric Remote-sensing Infrared Exoplanet Large-survey, was adopted as the fourth medium-class mission in ESA's Cosmic Vision programme to be launched in 2029. During its 4-year mission, Ariel will study what exoplanets are made of, how they formed and how they evolve, by surveying a diverse sample of about 1000 extrasolar planets, simultaneously in visible and infrared wavelengths. It is the first mission dedicated to measuring the chemical composition and thermal structures of hundreds of transiting exoplanets, enabling planetary science far beyond the boundaries of the Solar System. The payload consists of an off-axis Cassegrain telescope (primary mirror 1100 mm x 730 mm ellipse) and two separate instruments (FGS and AIRS) covering simultaneously 0.5-7.8 micron spectral range. The satellite is best placed into an L2 orbit to maximise the thermal stability and the field of regard. The payload module is passively cooled via a series of V-Groove radiators; the detectors for the AIRS are the only items that require active cooling via an active Ne JT cooler. The Ariel payload is developed by a consortium of more than 50 institutes from 16 ESA countries, which include the UK, France, Italy, Belgium, Poland, Spain, Austria, Denmark, Ireland, Portugal, Czech Republic, Hungary, the Netherlands, Sweden, Norway, Estonia, and a NASA contribution

Transit timings variations in the three-planet system : TOI-270

We present ground- and space-based photometric observations of TOI-270 (L231-32), a system of three transiting planets consisting of one super-Earth and two sub-Neptunes discovered by TESS around a bright (K-mag = 8.25) M3V dwarf. The planets orbit near low-order mean-motion resonances (5:3 and 2:1) and are thus expected to exhibit large transit timing variations (TTVs). Following an extensive observing campaign using eight different observatories between 2018 and 2020, we now report a clear detection of TTVs for planets c and d, with amplitudes of ∼10 min and a super-period of ∼3 yr, as well as significantly refined estimates of the radii and mean orbital periods of all three planets. Dynamical modelling of the TTVs alone puts strong constraints on the mass ratio of planets c and d and on their eccentricities. When incorporating recently published constraints from radial velocity observations, we obtain masses of Mb=1.48±0.18M⊕⁠, Mc=6.20±0.31M⊕⁠, and Md=4.20±0.16M⊕ for planets b, c, and d, respectively. We also detect small but significant eccentricities for all three planets : eb = 0.0167 ± 0.0084, ec = 0.0044 ± 0.0006, and ed = 0.0066 ± 0.0020. Our findings imply an Earth-like rocky composition for the inner planet, and Earth-like cores with an additional He/H2O atmosphere for the outer two. TOI-270 is now one of the best constrained systems of small transiting planets, and it remains an excellent target for atmospheric characterization

A Possible Alignment Between the Orbits of Planetary Systems and their Visual Binary Companions

Astronomers do not have a complete picture of the effects of wide-binary companions (semimajor axes greater than 100 au) on the formation and evolution of exoplanets. We investigate these effects using new data from Gaia Early Data Release 3 and the Transiting Exoplanet Survey Satellite mission to characterize wide-binary systems with transiting exoplanets. We identify a sample of 67 systems of transiting exoplanet candidates (with well-determined, edge-on orbital inclinations) that reside in wide visual binary systems. We derive limits on orbital parameters for the wide-binary systems and measure the minimum difference in orbital inclination between the binary and planet orbits. We determine that there is statistically significant difference in the inclination distribution of wide-binary systems with transiting planets compared to a control sample, with the probability that the two distributions are the same being 0.0037. This implies that there is an overabundance of planets in binary systems whose orbits are aligned with those of the binary. The overabundance of aligned systems appears to primarily have semimajor axes less than 700 au. We investigate some effects that could cause the alignment and conclude that a torque caused by a misaligned binary companion on the protoplanetary disk is the most promising explanation

Multidimensional signals and analytic flexibility: Estimating degrees of freedom in human speech analyses

Recent empirical studies have highlighted the large degree of analytic flexibility in data analysis which can lead to substantially different conclusions based on the same data set. Thus, researchers have expressed their concerns that these researcher degrees of freedom might facilitate bias and can lead to claims that do not stand the test of time. Even greater flexibility is to be expected in fields in which the primary data lend themselves to a variety of possible operationalizations. The multidimensional, temporally extended nature of speech constitutes an ideal testing ground for assessing the variability in analytic approaches, which derives not only from aspects of statistical modeling, but also from decisions regarding the quantification of the measured behavior. In the present study, we gave the same speech production data set to 46 teams of researchers and asked them to answer the same research question, resulting insubstantial variability in reported effect sizes and their interpretation. Using Bayesian meta-analytic tools, we further find little to no evidence that the observed variability can be explained by analysts’ prior beliefs, expertise or the perceived quality of their analyses. In light of this idiosyncratic variability, we recommend that researchers more transparently share details of their analysis, strengthen the link between theoretical construct and quantitative system and calibrate their (un)certainty in their conclusions

Animal models for corneal research. Animal experiments and innovative alternatives

La cornée est le hublot transparent de l’oeil. Bien que de nombreux modèles alternatifs utilisant des cornées animales ex vivo aient vu le jour durant ces 30 dernières années, les recherches préclinique (étude de nouvelles stratégies diagnostiques et thérapeutiques) et fondamentale sur la cornée ont toujours besoin de l’expérimentation animale in vivo. Elle fait aujourd’hui l’objet d’une réglementation stricte afin d’éviter tout abus et maltraitance. Les animaux les plus fréquemment utilisés en recherche cornéenne sont des mammifères (souris, rat, lapin, chat, chien, cochon, boeuf et primate non humain). Malgré leur proximité phylogénétique de l’Homme, ces animaux peuvent présenter des différences notables avec la cornée humaines qui doivent être connues pour ne pas induire de biais dans l’expérimentation. Les objectifs de cette thèse sont de mettre au point les modèles animaux et les méthodes alternatives nécessaires aux travaux du laboratoire BiiGC (EA 2521, Université de Saint-Étienne, France). Ils sont illustrés par 3 projets innovants : 1/une étude préclinique utilisant un modèle de kératoplastie transfixiante chez le lapin pour évaluer la prévention du rejet d’allogreffe de cornée par implant sous conjonctival de déxamethasone ; 2/Le développement d’un bioréacteur cornéen porcin pour l’analyse de la cicatrisation épithéliale ; 3/ l’utilisation d’un modèle lapin de lésion endothéliale pour l’étude de la régénération endothéliale. Ces 3 travaux innovant démontrent la diversité des modèles animaux nécessaires en recherche fondamentale et translationnelle.The cornea is the clear window of the eye. Although many alternative models using ex vivo animal corneas have emerged during the last 30 years, preclinical research (study of new diagnostic and therapeutic strategies) and fundamental corneal research still need animal experiments in vivo. The most commonly used animals in corneal research are mammals (mouse, rat, rabbit, cat, dog, pig, beef and non-human primate). Despite their phylogenetic proximity to humans, these animals may exhibit notable differences with the human cornea, which must be known so as not to induce bias into the experiment. The aims of this thesis are to develop the animal models and the alternative models necessary for the work of the BiiGC laboratory (EA2521, University of Saint-Etienne, France). They illustrated by 3 innovative projects: 1/ a preclinical study using penetrating keratoplasty model in rabbits to evaluate the prevention of corneal allografts rejection by a conjunctival implant of dexamethasone; 2/ The development of a porcine corneal bioreactor for the analysis of epithelial wound healing; 3/ The use of rabbit endothelial lesion model for the study of endothelial regeneration. These 3 innovative works demonstrate the diversity of animal models needed in fundamental and translational researc

Specular Microscopy of Human Corneas Stored in an Active Storage Machine

Purpose: Unlike corneas stored in cold storage (CS) which remain transparent and thin, corneas stored in organoculture (OC) cannot be assessed by specular microscopy (SM), because edema and posterior folds occur during storage and prevent from specular reflection. We previously developed an active storage machine (ASM) which restores the intraocular pressure while renewing the storage medium, thus preventing major stromal edema. Its transparent windows allow multimodal corneal imaging in a closed system. Aim: to present SM of corneas stored in this ASM. Methods: Ancillary study of two preclinical studies on corneas stored for one and three months in the ASM. A prototype non-contact SM was developed (CMOS camera, ×10 objective, collimated LED source, micrometric stage). Five non-overlapping fields (935 × 748 μm) were acquired in exactly the same areas at regular intervals. Image quality was graded according to defined categories (American Cornea Donor Study). The endothelial cell density (ECD) was measured with a center method. Finally, SMECD was also compared to Hoechst-stained cell nuclei count (HoechstECD). Results: The 62 corneas remained thin during storage, allowing SM at all time points without corneal deconditioning. Image quality varied depending on donors and days of control but, overall, in the 1100 images, we observed 55% of excellent and 30% of good quality images. SMECD did not differ from HoechstECD (p = 0.084). Conclusions: The ASM combines the advantages of CS (closed system) and OC (long-term storage). Specular microscopy is possible at any time in the ASM with a large field of view, making endothelial controls easy and safe

Specular Microscopy of Human Corneas Stored in an Active Storage Machine

Purpose: Unlike corneas stored in cold storage (CS) which remain transparent and thin, corneas stored in organoculture (OC) cannot be assessed by specular microscopy (SM), because edema and posterior folds occur during storage and prevent from specular reflection. We previously developed an active storage machine (ASM) which restores the intraocular pressure while renewing the storage medium, thus preventing major stromal edema. Its transparent windows allow multimodal corneal imaging in a closed system. Aim: to present SM of corneas stored in this ASM. Methods: Ancillary study of two preclinical studies on corneas stored for one and three months in the ASM. A prototype non-contact SM was developed (CMOS camera, ×10 objective, collimated LED source, micrometric stage). Five non-overlapping fields (935 × 748 μm) were acquired in exactly the same areas at regular intervals. Image quality was graded according to defined categories (American Cornea Donor Study). The endothelial cell density (ECD) was measured with a center method. Finally, SMECD was also compared to Hoechst-stained cell nuclei count (HoechstECD). Results: The 62 corneas remained thin during storage, allowing SM at all time points without corneal deconditioning. Image quality varied depending on donors and days of control but, overall, in the 1100 images, we observed 55% of excellent and 30% of good quality images. SMECD did not differ from HoechstECD (p = 0.084). Conclusions: The ASM combines the advantages of CS (closed system) and OC (long-term storage). Specular microscopy is possible at any time in the ASM with a large field of view, making endothelial controls easy and safe