Laboratoire Printemps

Iron refractory iron deficiency anemia is a hereditary recessive anemia due to a defect in the TMPRSS6 gene encoding Matriptase-2. This protein is a transmembrane serine protease that plays an essential role in down-regulating hepcidin, the key regulator of iron homeostasis. Hallmarks of this disease are microcytic hypochromic anemia, low transferrin saturation and normal/high serum hepcidin values. The anemia appears in the post-natal period, although in some cases it is only diagnosed in adulthood. The disease is refractory to oral iron treatment but shows a slow response to intravenous iron injections and partial correction of the anemia. To date, 40 different Matriptase-2 mutations have been reported, affecting all the functional domains of the large ectodomain of the protein. In vitro experiments on transfected cells suggest that Matriptase-2 cleaves Hemojuvelin, a major regulator of hepcidin expression and that this function is altered in this genetic form of anemia. In contrast to the low/undetectable hepcidin levels observed in acquired iron deficiency, in patients with Matriptase-2 deficiency, serum hepcidin is inappropriately high for the low iron status and accounts for the absent/delayed response to oral iron treatment. A challenge for the clinicians and pediatricians is the recognition of the disorder among iron deficiency and other microcytic anemias commonly found in pediatric patients. The current treatment of iron refractory iron deficiency anemia is based on parenteral iron administration; in the future, manipulation of the hepcidin pathway with the aim of suppressing it might become an alternative therapeutic approach.

[1] A 5+ year record of satellite measurements of nitrogen dioxide columns from the Ozone Monitoring Instrument (OMI) is evaluated to establish the quality of the OMI retrievals and to test our understanding of stratospheric NO2. The use of assimilation techniques to retrieve stratospheric vertical columns of NO2 from OMI slant column observations is described in detail. Over remote areas the forecast model state is generally within 0.15 × 1015 molecules/cm2 of the analysis. Dutch OMI NO2 (DOMINO) and Standard Product (SP) stratospheric NO2 columns agree within 0.3 × 1015 molecules/cm2 (13%) with independent, ground-based measurements. This is comparable to the level of consistency (15–20%) among ground-based techniques. On average, DOMINO stratospheric NO2 is higher than SP by 0.2 × 1015 molecules/cm2, but larger differences occur on the synoptic scale. Overlapping OMI orbits poleward of 30° enabled us to extract information on the diurnal variation in stratospheric NO2. We find that in the Arctic, the daytime increase of NO2 has a distinct seasonal dependence that peaks in spring and fall. Daytime increase rates inside the denoxified Arctic polar vortex are low, but we find high rates (>0.4 × 1015 molecules/cm2/h) outside the vortex. A multilinear regression to the DOMINO record shows a distinct quasi-biennial oscillation (QBO) signal in stratospheric NO2 columns over the tropics. The QBO's amplitude is comparable to the annual cycle and stronger over the Southern Hemisphere than over the Northern Hemisphere. We infer near-identical trends from DOMINO observations (+0.4%/decade) as from ground-based instrumentation over Lauder (+0.6%/decade) in the 2004–2010 period.

Context. The Gaia Data Release 2 (DR2) contains the first release of radial velocities complementing the kinematic data of a sample of about 7 million relatively bright, late-type stars. Aims. This paper provides a detailed description of the Gaia spectroscopic data processing pipeline, and of the approach adopted to derive the radial velocities presented in DR2. Methods. The pipeline must perform four main tasks: (i) clean and reduce the spectra observed with the Radial Velocity Spectrometer (RVS); (ii) calibrate the RVS instrument, including wavelength, straylight, line-spread function, bias non-uniformity, and photometric zeropoint; (iii) extract the radial velocities; and (iv) verify the accuracy and precision of the results. The radial velocity of a star is obtained through a fit of the RVS spectrum relative to an appropriate synthetic template spectrum. An additional task of the spectroscopic pipeline was to provide first-order estimates of the stellar atmospheric parameters required to select such template spectra. We describe the pipeline features and present the detailed calibration algorithms and software solutions we used to produce the radial velocities published in DR2. Results. The spectroscopic processing pipeline produced median radial velocities for Gaia stars with narrow-band near-IR magnitude G RVS ≤ 12 (i.e. brighter than V ~ 13). Stars identified as double-lined spectroscopic binaries were removed from the pipeline, while variable stars, single-lined, and non-detected double-lined spectroscopic binaries were treated as single stars. The scatter in radial velocity among different observations of a same star, also published in Gaia DR2, provides information about radial velocity variability. For the hottest ( T eff ≥ 7000 K) and coolest ( T eff ≤ 3500 K) stars, the accuracy and precision of the stellar parameter estimates are not sufficient to allow selection of appropriate templates. The radial velocities obtained for these stars were removed from DR2. The pipeline also provides a first-order estimate of the performance obtained. The overall accuracy of radial velocity measurements is around ~200–300 m s −1 , and the overall precision is ~1 km s −1 ; it reaches ~200 m s −1 for the brightest stars.

Abstract. Accurate long-term monitoring of total ozone is one of the most important requirements for identifying possible natural or anthropogenic changes in the composition of the stratosphere. For this purpose, the NDACC (Network for the Detection of Atmospheric Composition Change) UV-visible Working Group has made recommendations for improving and homogenizing the retrieval of total ozone columns from twilight zenith-sky visible spectrometers. These instruments, deployed all over the world in about 35 stations, allow measuring total ozone twice daily with limited sensitivity to stratospheric temperature and cloud cover. The NDACC recommendations address both the DOAS spectral parameters and the calculation of air mass factors (AMF) needed for the conversion of O3 slant column densities into vertical column amounts. The most important improvement is the use of O3 AMF look-up tables calculated using the TOMS V8 (TV8) O3 profile climatology, that allows accounting for the dependence of the O3 AMF on the seasonal and latitudinal variations of the O3 vertical distribution. To investigate their impact on the retrieved ozone columns, the recommendations have been applied to measurements from the NDACC/SAOZ (Système d'Analyse par Observation Zénithale) network. The revised SAOZ ozone data from eight stations deployed at all latitudes have been compared to TOMS, GOME-GDP4, SCIAMACHY-TOSOMI, SCIAMACHY-OL3, OMI-TOMS, and OMI-DOAS satellite overpass observations, as well as to those of collocated Dobson and Brewer instruments at Observatoire de Haute Provence (44° N, 5.5° E) and Sodankyla (67° N, 27° E), respectively. A significantly better agreement is obtained between SAOZ and correlative reference ground-based measurements after applying the new O3 AMFs. However, systematic seasonal differences between SAOZ and satellite instruments remain. These are shown to mainly originate from (i) a possible problem in the satellite retrieval algorithms in dealing with the temperature dependence of the ozone cross-sections in the UV and the solar zenith angle (SZA) dependence, (ii) zonal modulations and seasonal variations of tropospheric ozone columns not accounted for in the TV8 profile climatology, and (iii) uncertainty on the stratospheric ozone profiles at high latitude in the winter in the TV8 climatology. For those measurements mostly sensitive to stratospheric temperature like TOMS, OMI-TOMS, Dobson and Brewer, or to SZA like SCIAMACHY-TOSOMI, the application of temperature and SZA corrections results in the almost complete removal of the seasonal difference with SAOZ, improving significantly the consistency between all ground-based and satellite total ozone observations.

In 1976, the Viking landers carried out the most comprehensive search for organics and microbial life in the martian regolith. Their results indicate that Mars' surface is lifeless and, surprisingly, depleted in organics at part-per-billion levels. Several biology experiments on the Viking landers gave controversial results that have since been explained by the presence of oxidizing agents on the surface of Mars. These oxidants may degrade abiotic or biological organics, resulting in their nondetection in the regolith. As several exploration missions currently focus on the detection of organics on Mars (or will do so in the near future), knowledge of the oxidative state of the surface is fundamental. It will allow for determination of the capability of organics to survive on a geological timescale, the most favorable places to seek them, and the best methods to process the samples collected at the surface. With this aim, we review the main oxidants assumed to be present on Mars, their possible formation pathways, and those laboratory studies in which their reactivity with organics under Mars-like conditions has been evaluated. Among the oxidants assumed to be present on Mars, only four have been detected so far: perchlorate ions (ClO4−) in salts, hydrogen peroxide (H2O2) in the atmosphere, and clays and metal oxides composing surface minerals. Clays have been suggested as catalysts for the oxidation of organics but are treated as oxidants in the following to keep the structure of this article straightforward. This work provides an insight into the oxidizing potential of the surface of Mars and an estimate of the stability of organic matter in an oxidizing environment. Key Words: Mars surface—Astrobiology—Oxidant—Chemical reactions. Astrobiology 16, 977–996.

La construction sociale de l’insertion professionnelle L’article explicite les significations les plus fréquentes de l’expression “construction sociale” en prenant comme exemple l’insertion des jeunes dans le travail. Le premier sens renvoie au fait que les faits sociaux — par exemple l’insertion— sont des productions de l’histoire. Le fait, pour des jeunes, de devoir chercher, de manière souvent longue et difficile, un emploi en sortant du système scolaire est relativement récent et résulte d’un double mouvement historique: celui qui sépare la formation du travail et celui, plus récent, qui brise les règles d’équivalence automatique entre niveaux de formation et niveaux d’emploi. Le second sens renvoie aux spécificités “sociétales” de chaque nation qui organisent de manières diverses les relations entre modes d’apprentissage, organisation du travail et relations industrielles. Le dernier est celui qui résulte d’un point de vue stratégique sur le social — l’insertion— en en faisant la résultante du jeu des acteurs pourvus d’intérêts divergents et de valeurs différentes. La combinaison de ces trois sens rend les approches empiriques de l’insertion complexes puisque devant tenir compte de la genèse historique, des comparaisons internationales et d’un travail de terrain auprès de tous les acteurs concernés, y compris les jeunes eux-mêmes.

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Abstract. We show that a fire plume injected into the lower stratosphere at high northern latitudes during the Canadian wildfire event in August 2017 partly reached the tropics. The transport to the tropics was mediated by the anticyclonic flow of the Asian monsoon circulation. The fire plume reached the Asian monsoon area in late August/early September, when the Asian monsoon anticyclone (AMA) was still in place. While there is no evidence of mixing into the center of the AMA, we show that a substantial part of the fire plume is entrained into the anticyclonic flow at the AMA edge and is transported from the extratropics to the tropics, and possibly the Southern Hemisphere particularly following the north–south flow on the eastern side of the AMA. In the tropics the fire plume is lifted by ∼5 km in 7 months. Inside the AMA we find evidence of the Asian tropopause aerosol layer (ATAL) in August, doubling background aerosol conditions with a calculated top of the atmosphere shortwave radiative forcing of −0.05 W m−2. The regional climate impact of the fire signal in the wider Asian monsoon area in September exceeds the impact of the ATAL by a factor of 2–4 and compares to that of a plume coming from an advected moderate volcanic eruption. The stratospheric, trans-continental transport of this plume to the tropics and the related regional climate impact point to the importance of long-range dynamical interconnections of pollution sources.

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Négociations, contre-interprétations, ajustements de sens Dans la sociologie française l’entretien, à orientation biographique, apparaît comme une méthode particulièrement prisée. Pourtant la réflexivité des sociologues sur cette méthode s’exerce trop souvent à distance des aspects les plus concrets du travail d’enquête. En effet, les préceptes de bienveillance et de neutralité restent à l’écart de la conduite effective de l’entretien, et l’assimilation du rapport d’enquête à une domination est insuffisante pour saisir le travail d’interprétation de la situation par les protagonistes. A rebours, cet article considère l’entretien biographique au plus près de sa production, à travers l’interaction entre le sociologue et l’interviewé. Il met l’accent sur les définitions de situation, les échanges et les ajustements portant sur ce que les participants font. Leur activité, discursive et interprétative, est saisie à partir de de trois enquêtes empiriques menées auprès de populations différenciées, qui proposent au sociologue interviewer, selon des modalités spécifiques, des interprétations contrastées de la situation d’enquête.

Abstract. In this paper we present the latest refinements brought to the DARDAR-CLOUD product, which contains ice cloud microphysical properties retrieved from the cloud radar and lidar measurements from the A-Train mission. Based on a large dataset of in situ ice cloud measurements, the parameterizations used in the microphysical model of the algorithm – i.e. the normalized particle size distribution, the mass–size relationship, and the parameterization of the a priori value of the normalized number concentration as a function of temperature – were assessed and refined to better fit the measurements, keeping the same formalism as proposed in DARDAR basis papers. Additionally, in regions where lidar measurements are available, the lidar ratio retrieved for ice clouds is shown to be well constrained by the lidar–radar synergy. Using this information, the parameterization of the lidar ratio was also refined, and the new retrieval equals on average 35±10 sr in the temperature range between −60 and −20 ∘C. The impact of those changes on the retrieved ice cloud properties is presented in terms of ice water content (IWC) and effective radius. Overall, IWC values from the new DARDAR-CLOUD product are on average 16 % smaller than the previous version, leading to a 24 % reduction in the ice water path. In parallel, the retrieved effective radii increase by 5 % to 40 %, depending on temperature and the availability of the instruments, with an average difference of +15 %. Modifications of the microphysical model strongly affect the ice water content retrievals with differences that were found to range from −50 % to +40 %, depending on temperature and the availability of the instruments. The largest differences are found for the warmest temperatures (between −20 and 0 ∘C) in regions where the cloud microphysical processes are more complex and where the retrieval is almost exclusively based on radar-only measurements. The new lidar ratio values lead to a reduction of IWC at cold temperatures, the difference between the two versions increasing from around 0 % at −30 ∘C to 70 % below −80 ∘C, whereas effective radii are not impacted.

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Abstract The Imaging UltraViolet Spectrograph (IUVS) instrument of the Mars Atmosphere and Volatile EvolutioN (MAVEN) mission has acquired data on Mars for more than one Martian year. During this time, beginning with March 2015, hundreds of stellar occultations have been observed, in 12 dedicated occultation campaigns, executed on average every 2 to 3 months. The occultations cover the latitudes from 80°S to 75°N and the full range longitude and local times with relatively sparse sampling. From these measurements we retrieve CO 2 , O 2 , and O 3 number densities as well as temperature profiles in the altitude range from 20 to 160 km, covering 8 orders of magnitude in pressure from ∼2 × 10 1 to ∼4 × 10 −7 Pa. These data constrain the composition and thermal structure of the atmosphere. The O 2 mixing ratios retrieved during this study show a high variability from 1.5 × 10 −3 to 6 × 10 −3 ; however, the mean value seems to be constant with solar longitude. We detect ozone between 20 and 60 km. In many profiles there is a well‐defined peak between 30 and 40 km with a maximum density of 1–2 ×10 9 cm −3 . Examination of the vertical temperature profiles reveals substantial disagreement with models, with observed temperatures both warmer and colder than predicted. Examination of the altitude profiles of density perturbations and their variation with longitude shows structured atmospheric perturbations at altitudes above 100 km that are likely nonmigrating tides. These perturbations are dominated by zonal wave numbers 2 and 3 with amplitudes greater than 45%.

La variation des postures dans l’activité discursive implique des variations dans les distributions du vocabulaire qui ne sont pas sans effet sur la discrimination des mondes lexicaux par la méthode statistique d’analyse des textes ALCESTE (Analyse des Lexèmes Cooccurrents pour un Ensemble de Segmentations du Texte en Énoncés). En 1992, lors de nos premières rencontres, Pierre Achard s’aperçut que les trois mondes lexicaux résultants de l’analyse des 220 récits de cauchemars de l’étude que nous lui soumettions permettaient de différencier également les trois positions d’énonciation qu’il avait distinguées dans son article de mars 1991, « Une approche discursive des questionnaires » à propos d’une enquête pendant la guerre d’Algérie. Peut-on aujourd’hui donner quelques pistes sur les raisons de cette convergence ? C’est ce que nous tenterons de discuter ici.

Abstract The Earth's hydrogen exosphere Lyman‐ α radiation was mapped with the Solar Wind Anisotropies/Solar and Heliospheric Observatory (SWAN/SOHO) instrument in January 1996, 1997, and 1998 (low solar activity). The use of a hydrogen absorption cell allowed to disentangle the interplanetary emission from the geocoronal one and to assign the absorbed signal almost entirely to the geocorona. The geocorona was found to extend at least up to 100 Earth radii ( R E ) with an intensity of 5 Rayleigh, an unprecedented distance well exceeding the recent results of Lyman Alpha Imaging Camera (LAICA) imager (∼50 R E ), and encompassing the orbit of the Moon (∼60 R E ). We developed a numerical kinetic model of the hydrogen atoms distribution in the exosphere, which includes the solar Lyman‐ α radiation pressure and the ionization. The radiation pressure compresses the H exosphere on the dayside, producing a bulge of H density between 3 and 20 R E , which fits observed intensities very well. The SWAN Lyman‐ α distribution of intensity was compared both to LAICA (2015) and to Orbiting Geophysical Observatory number 5 (1968) measurements. Integrated H densities of SWAN at a tangent distance of 7 R E are larger than LAICA/Orbiting Geophysical Observatory number 5 by factors 1.1–2.5, while we should expect a stronger effect of the radiation pressure at solar max. We discuss the possible role of H atoms in satellite orbits to explain this apparent contradiction. An onion‐peeling technique is used to retrieve hydrogen number density in the exosphere for the three SWAN observations. They show an excess of density versus models at large distances, which is likely due to nonthermal atoms (not in the model).

Les articles rassemblés dans ce dossier pointent, chacun à leur manière et sur des terrains différents, le caractère problématique des processus de professionnalisation. Quels que soient les phénomènes étudiés, la professionnalisation apparaît inachevée, inaccomplie, incomplète, imparfaitement réalisée. Elle est prise dans une tension entre une perspective désirable (pour certains acteurs et institutions au moins) et les difficultés qui entravent la progression vers cet objectif. Avec leur or...

Abstract The Perseverance rover landed in the ancient lakebed of Jezero crater, Mars on February 2021. Here, we assess the mineralogy of the rocks, regolith, and dust measured during the first year of the mission on the crater floor, using the visible and near‐infrared spectrometer of SuperCam onboard the Perseverance rover. Most of the minerals detected from orbit are present in the bedrock, with olivine‐bearing rocks at the bottom of the stratigraphy and high‐Ca pyroxene‐bearing rocks at the top. This is distinct from the overall low‐Ca pyroxene‐bearing composition of the watershed of Jezero and points toward an igneous origin. Alteration mineral phases were detected in most of the rocks analyzed in low proportions, suggesting that aqueous alteration of the crater floor has been spatially widespread, but limited in intensity and/or time. The diverse aqueous mineralogy suggests that the aqueous alteration history of the crater floor consists of at least two stages, to form phyllosilicates and oxyhydroxides, and later sulfates. We interpret their formation in a lake or under deeper serpentinization conditions and in an evaporative environment, respectively. Spectral similarities of dust with some rock coatings suggest widespread past processes of dust induration under liquid water activity late in the history of Jezero. Analysis of the regolith revealed some local inputs from the surrounding rocks. Relevant to the Mars Sample Return mission, the spectral features exhibited by the rocks sampled on the crater floor are representative of the diversity of spectra measured on the geological units investigated by the rover.

Abstract Over the Southern Ocean (SO, 40°S–70°S), climate models have consistently underestimated solar reflection. Here we evaluate the relationship between cloud profiles, cloud phase and radiation over the SO in Coupled Model Intercomparison Project Phase 6 (CMIP6) models against Clouds and the Earth's Radiant Energy System and Cloud‐Aerosol Lidar and Infrared Pathfinder Satellite Observations. We find that the lack of solar reflection is slightly improved in CMIP6 models compared to CMIP5's, attributable to a better representation of cloud fraction and phase. We show that clouds have a different vertical structure and radiative effect south and north of where the 0°C isotherm meets the surface (∼55°S). Although the models capture the greater vertical extent of clouds south of 55°S, they fail to reproduce the observed increase in solar reflection, which we pinpoint to cloud phase biases. Increasing CMIP6 supercooled liquid cloud opacity should help reduce their persistent shortwave biases.

En combinant analyses quantitative et qualitative (données de l’Enquête nationale sur les violences envers les femmes d’une part, entretiens approfondis ad hoc d’autre part), cet article explore les relations entre sentiment d’insécurité, expérience de victimation et mobilité des femmes dans les espaces publics, questions généralement évoquées deux à deux. Si les femmes sont relativement peu nombreuses à déclarer spontanément leurs peurs de sortir seule, l’étude de leurs pratiques effectives et du contenu de leurs discours permet de nuancer un tel constat. En effet, bon nombre de femmes ne sont pas confrontées à la question de sortir seule le soir, notamment celles qui vivent en couple ou celles qui, par la division sexuelle du travail, manquent de temps libre. De plus, l’analyse des pratiques de celles qui sortent seules laisse penser que leurs déplacements nocturnes font l’objet d’une vaste mise en condition : il existe une véritable vigilance mentale qui se révèle au travers de nombreuses et incontournables tactiques d’évitement et que renforce encore l’expérience de victimation. Les agressions subies dans les espaces publics ne semblent pas entraver la mobilité des femmes. Toutefois, les violences, mêmes les plus anodines en apparence, limitent leur liberté en portant une menace qui pèse, au-delà du moment où elles se produisent, et accroissent les sentiments de crainte que de nombreuses femmes disent éprouver à l’égard de l’extérieur.

Abstract The dual spacecraft mission BepiColombo is the first joint mission between the European Space Agency (ESA) and the Japanese Aerospace Exploration Agency (JAXA) to explore the planet Mercury. BepiColombo was launched from Kourou (French Guiana) on October 20th, 2018, in its packed configuration including two spacecraft, a transfer module, and a sunshield. BepiColombo cruise trajectory is a long journey into the inner heliosphere, and it includes one flyby of the Earth (in April 2020), two of Venus (in October 2020 and August 2021), and six of Mercury (starting from 2021), before orbit insertion in December 2025. A big part of the mission instruments will be fully operational during the mission cruise phase, allowing unprecedented investigation of the different environments that will encounter during the 7-years long cruise. The present paper reviews all the planetary flybys and some interesting cruise configurations. Additional scientific research that will emerge in the coming years is also discussed, including the instruments that can contribute.