A chemical survey of exoplanets with ARIEL

Thousands of exoplanets have now been discovered with a huge range of masses, sizes and orbits: from rocky Earth-like planets to large gas giants grazing the surface of their host star. However, the essential nature of these exoplanets remains largely mysterious: there is no known, discernible pattern linking the presence, size, or orbital parameters of a planet to the nature of its parent star. We have little idea whether the chemistry of a planet is linked to its formation environment, or whether the type of host star drives the physics and chemistry of the planet’s birth, and evolution. ARIEL was conceived to observe a large number (~1000) of transiting planets for statistical understanding, including gas giants, Neptunes, super-Earths and Earth-size planets around a range of host star types using transit spectroscopy in the 1.25–7.8 μm spectral range and multiple narrow-band photometry in the optical. ARIEL will focus on warm and hot planets to take advantage of their well-mixed atmospheres which should show minimal condensation and sequestration of high-Z materials compared to their colder Solar System siblings. Said warm and hot atmospheres are expected to be more representative of the planetary bulk composition. Observations of these warm/hot exoplanets, and in particular of their elemental composition (especially C, O, N, S, Si), will allow the understanding of the early stages of planetary and atmospheric formation during the nebular phase and the following few million years. ARIEL will thus provide a representative picture of the chemical nature of the exoplanets and relate this directly to the type and chemical environment of the host star. ARIEL is designed as a dedicated survey mission for combined-light spectroscopy, capable of observing a large and well-defined planet sample within its 4-year mission lifetime. Transit, eclipse and phase-curve spectroscopy methods, whereby the signal from the star and planet are differentiated using knowledge of the planetary ephemerides, allow us to measure atmospheric signals from the planet at levels of 10–100 part per million (ppm) relative to the star and, given the bright nature of targets, also allows more sophisticated techniques, such as eclipse mapping, to give a deeper insight into the nature of the atmosphere. These types of observations require a stable payload and satellite platform with broad, instantaneous wavelength coverage to detect many molecular species, probe the thermal structure, identify clouds and monitor the stellar activity. The wavelength range proposed covers all the expected major atmospheric gases from e.g. H2O, CO2, CH4 NH3, HCN, H2S through to the more exotic metallic compounds, such as TiO, VO, and condensed species. Simulations of ARIEL performance in conducting exoplanet surveys have been performed – using conservative estimates of mission performance and a full model of all significant noise sources in the measurement – using a list of potential ARIEL targets that incorporates the latest available exoplanet statistics. The conclusion at the end of the Phase A study, is that ARIEL – in line with the stated mission objectives – will be able to observe about 1000 exoplanets depending on the details of the adopted survey strategy, thus confirming the feasibility of the main science objectives.Peer reviewedFinal Published versio

Embedded Virtual Views for Augmented Reality Navigation

Figure 1: An embedded virtual view allows users to follow a guided route, without leaving the egocentric viewpoint. (a) The navigation aid turns around the corner and the user’s view is blocked by the building. (b) By extending the egocentric viewpoint with an additional embedded virtual view, the user is still able to perceive the route indicated by the navigation aid. Note that the additional view embeds the navigation aid correctly in the environment. In this paper, we present virtual embedded views used for turnbased pedestrian navigation in Augmented Reality (AR). Embedded views allow users to see around occluding structures and at the same time seamlessly integrate the augmented navigation aid into the otherwise occluded view. Users get a preview on upcoming route changes, without the need to consult an additional map view. We compare embedded views to other methods revealing the occluded navigation aids. We demonstrate that the technique is more screen-space efficient when compared to a typical x-ray vision technique, and may better facilitate the mental linking of information, when compared to a mirror

Transitional Augmented Reality navigation for live captured scenes

Figure 1: After placing physical objects on a table, our system offers the possibility to structurally navigate an unprepared scene with a set of new transitional navigation techniques in AR (Left) and VR (Right) modes. The techniques seamlessly switch from AR to VR modes. Augmented Reality (AR) applications require knowledge about the real world environment in which they are used. This knowledge is often gathered while developing the AR application and stored for future uses of the application. Consequently, changes to the real world lead to a mismatch between the previously recorded data and the real world. New capturing techniques based on dense Simul-taneous Localization and Mapping (SLAM) not only allow users to capture real world scenes at run-time, but also enables them to capture changes of the world. However, instead of using previously recorded and prepared scenes, users must interact with an unpre-pared environment. In this paper, we present a set of new interaction techniques that support users in handling captured real world envi-ronments. The techniques present virtual viewpoints of the scene based on a scene analysis and provide natural transitions between the AR view and virtual viewpoints. We demonstrate our approach with a SLAM based prototype that allows us to capture a real world scene and describe example applications of our system

Effect of oral citrulline supplementation on whole body protein metabolism in adult patients with short bowel syndrome A pilot, randomized, double-blind, cross-over study

International audienceBACKGROUND & AIMS: As citrulline is produced by small intestine, plasma citrulline concentration is decreased and may become essential in patients with short bowel syndrome (SBS). In a rat model of SBS, citrulline supplementation enhanced muscle protein synthesis. The aim of the study was to determine whether citrulline impacts whole body protein metabolism in patients with SBS. METHODS: Nine adults with non-malignant SBS (residual small bowel 90 ± 48 cm; mean ± SD) who were in near-normal nutritional status without any artificial nutrition, were recruited long after surgery. They received 7-day oral supplementation with citrulline (0.18 g/kg/day), or an iso-nitrogenous placebo in a randomized, double-blind, cross-over design with a 13-day wash-out between regimens, and an intravenous 5-h infusion of L-[1-13C]-leucine in the postabsorptive state to assess protein metabolism after each regimen. RESULTS: Plasma citrulline concentration rose 17-fold (25 ± 9 vs. 384 ± 95 μmol/L) and plasma arginine 3-fold after oral citrulline supplementation (both p < 4 × 10-6). Supplementation did not alter leucine appearance rate (97 ± 5 vs. 97 ± 5 μmol kg-1.h-1; p = 0.88), leucine oxidation (14 ± 1 vs. 12 ± 1 μmol kg-1.h-1; p = 0.22), or non-oxidative leucine disposal (NOLD), an index of whole-body protein synthesis (83 ± 4 vs. 85 ± 5 μmol kg-1.h-1; p = 0.36), nor insulin or IGF-1 plasma concentrations. In each of the 3 patients with baseline citrulline<20 μmol/L, citrulline supplementation increased NOLD. Among the 7 patients with plasma citrulline <30 μmol/L, the effect of supplementation on NOLD correlated inversely (r2 = 0.81) with baseline plasma citrulline concentration. CONCLUSION: 1) Oral citrulline supplementation enhances citrulline and arginine bioavailability in SBS patients. 2) Oral citrulline supplementation does not have any anabolic effect on whole body protein metabolism in patients with SBS in good nutritional status, in the late phase of intestinal adaptation, and with near-normal baseline citrulline homeostasis. 3) Whether oral citrulline would impact whole body protein anabolism in severely malnourished SBS patients in the early adaptive period, and with baseline plasma citrulline below 20 μmol/L, warrants further study. Registered under ClinicalTrials.gov Identifier no. NCT01386034

Omnikinect: Real-time dense volumetric data acquisition and applications

Real-time three-dimensional acquisition of real-world scenes has many important applications in computer graphics, computer vision and human-computer interaction. Inexpensive depth sensors such as the Microsoft Kinect allow to leverage the development of such applications. However, this technology is still relatively recent, and no detailed studies on its scalability to dense and view-independent acquisition have been reported. This paper addresses the question of what can be done with a larger number of Kinects used simultaneously. We describe an interference-reducing physical setup, a calibration procedure and an extension to the KinectFusion algorithm, which allows to produce high quality volumetric reconstructions from multiple Kinects whilst overcoming systematic errors in the depth measurements. We also report on enhancing image based visual hull rendering by depth measurements, and compare the results to KinectFusion. Our system provides practical insight into achievable spatial and radial range and into bandwidth requirements for depth data acquisition. Finally, we present a number of practical applications of our system

Study of the suitability of 3D printing for Ultra-High Vacuum applications

International audienceIn the recent year additive manufacturing (3D printing) has revolutionized mechanical engineering by allowing the quick production of mechanical components with complex shapes. So far most of these components are made in plastic and therefore can not be used in accelerator beam pipes. We have investigated samples printed using a metal 3D printer to study their behavior under vacuum. We report on our first tests showing that such samples are vacuum compatible and comparing pumping time

Varia 80

À NOS LECTEURS Dans le numéro précédent, nous annoncions : « une fois n’est pas coutume », pour expliquer que cette livraison ne présentait qu’un dossier thématique sans autres articles versés dans la rubrique « varia ». En conséquence, nous disposions de plusieurs contributions qui étaient en attente depuis quelques mois et qu’il était impossible de rassembler dans un dossier thématique. Il importait donc de les publier sans trop tarder. D’où la décision de les donner à lire dans ce n° 80 qui ne contient, lui aussi de manière inhabituelle, qu’un dossier seul se caractérisant par la diversité des sujets traités. Ce dossier est, en quelque sorte, un ensemble de « varia » suffisamment copieux pour nous dispenser de publier, dans la rubrique « édition », un document ou un témoignage ou encore une traduction. Pour les prochains numéros à venir, nous renouerons avec nos habitudes en présentant un dossier thématique – défini jusqu’en 2022 – des articles variés et des publications d’inédits. Les articles en attente que nous possédions parlent de littérature, de poésie, d’historiens, de « motif aggadique » et aussi des ouvriers du diamant à Anvers. Cette énumération dit la diversité que peuvent recouvrir les études juives. Ce constat nous a guidés dans le choix du titre attribué au dossier. Une difficulté a surgi : trouver une illustration pour la première page de couverture pouvant évoquer cet ensemble quelque peu disparate. Après des hésitations, notre décision s’est arrêtée sur une estampe d’Abram Krol qui se trouve au Musée d’Art et d’Histoire du Judaïsme à Paris(n° d’inventaire97.19.016.6). Nous remercions vivement le Musée pour nous avoir autorisés à utiliser son fonds très riche. Cela nous fournit l’occasion de faire connaître davantage le graveur Abram Krol. Originaire de Pabianice près de Lodz et issu d’une famille juive religieuse, Abram Krol (1919-2001) arrive en France en 1938 pour suivre des études à l’Institut technique de Caen. La déclaration de guerre vient troubler ce projet et le jeune Abram s’engage dans la Légion étrangère (Régiment de Marche des Volontaires Étrangers). Démobilisé après la défaite de la France, il se trouve en Avignon, sans famille et sans le sou. Il déniche un pénible travail dans un garage mais la rencontre avec un ébéniste le convainc de suivre un enseignement artistique à l’École des Beaux Arts d’Avignon. L’occupation de toute la France vient perturber cet autre projet et Abram Krol, proscrit, doit vivre sous une fausse identité jusqu’à la fin de la guerre qui le trouve à Paris. En 1947, il se lie avec Joseph Hecht (1891-1951), Polonais et juif également, qui l’initie à la gravure. Après le décès de son maître, il crée ses propres œuvres et commence à connaître un certain renom[1]. Andrée Lerousseau a écrit un bel hommage au poète Claude Vigée, disparu le 2 octobre dernier, à la veille de son centième anniversaire. Il était né le 3 janvier 1921 dans cette Alsace à laquelle il accorda une grande amitié et une fidélité inébranlable tout en assumant sa judéité ; deux belles raisons pour qu’il s’engage dans la Résistance. L’absence de la rubrique « Varia » a permis d’en introduire une autre : « Lecture ». Monique Heddebaut a transformé une note de lecture en un quasi article de six pages. Avec force détails, elle rend compte d’un ouvrage de Georges Waysand, Profession du père, fusillé, et s’attarde fort heureusement sur le parcours des parents de l’auteur qu’elle a côtoyé. Polonais, juifs et communistes, présents auprès des Républicains dans la Guerre d’Espagne, tout naturellement ils entrent en Résistance au prix de la fusillade pour le père et de la déportation pour la mère qui doit cacher son enfant né dans la clandestinité. Nous reprenons notre habitude en consacrant les dernières pages à quelques recensions d’ouvrages. À toutes et à tous, bonne lecture Tsafon Remarque : Comme toujours, nous laissons aux auteurs le choix d’écrire le substantif « juif » avec ou sans majuscule. [1] Cette trop courte biographie doit beaucoup à la présentation de Pierre-Yves Corbel sur le site internet du Centre national des arts plastiques (CNAP)

Is it Possible to Use Additive Manufacturing for Accelerator UHV Beam Pipes?

International audienceRecently, additive manufacturing (AM) has revolutionized mechanical engineering by allowing the quick production of mechanical components with complex shapes. AM by selective laser melting (SLM) is an advanced manufacturing process which uses lasers to melt metal powders one layer at a time to produce final 3D components. This technology could be also used to make Ultra High Vacuum components. Therefore, we investigated in this work the reproducibility of AM 316L stainless steel properties for different specimen supplied by several manufacturers with the same SLM process. Clearly, the microstructure and therefore the mechanical properties of the investigated AM samples are different as a function of manufacturers: indeed, they are largely influenced by processing parameters, which produces heterogeneous and anisotropic microstructures that differ from traditional wrought counterparts. Samples were also submitted to bake cycles at high temperature, in order to check the structural stability of material properties after heat treatments. The outgassing rates and the secondary emission yield of vacuum components constructed from AM 316L were also measured. Finally, the possibility to use AM for accelerator beam pipes will be discussed