Super-heavy fermion material as metallic refrigerant for adiabatic demagnetization cooling

Low-temperature refrigeration is of crucial importance in fundamental research of condensed matter physics, as the investigations of fascinating quantum phenomena, such as superconductivity, superfluidity and quantum criticality, often require refrigeration down to very low temperatures. Currently, cryogenic refrigerators with $^3$He gas are widely used for cooling below 1 Kelvin. However, usage of the gas is being increasingly difficult due to the current world-wide shortage. Therefore, it is important to consider alternative methods of refrigeration. Here, we show that a new type of refrigerant, super-heavy electron metal, YbCo$_2$Zn$_{20}$, can be used for adiabatic demagnetization refrigeration, which does not require 3He gas. A number of advantages includes much better metallic thermal conductivity compared to the conventional insulating refrigerants. We also demonstrate that the cooling performance is optimized in Yb$_{1-x}$Sc$_x$Co$_2$Zn$_{20}$ by partial Sc substitution with $x\sim$0.19. The substitution induces chemical pressure which drives the materials close to a zero-field quantum critical point. This leads to an additional enhancement of the magnetocaloric effect in low fields and low temperatures enabling final temperatures well below 100 mK. Such performance has up to now been restricted to insulators. Since nearly a century the same principle of using local magnetic moments has been applied for adiabatic demagnetization cooling. This study opens new possibilities of using itinerant magnetic moments for the cryogen-free refrigeration

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

The Athena X-ray Integral Field Unit: a consolidated design for the system requirement review of the preliminary definition phase

The Athena X-ray Integral Unit (X-IFU) is the high resolution X-ray spectrometer, studied since 2015 for flying in the mid-30s on the Athena space X-ray Observatory, a versatile observatory designed to address the Hot and Energetic Universe science theme, selected in November 2013 by the Survey Science Committee. Based on a large format array of Transition Edge Sensors (TES), it aims to provide spatially resolved X-ray spectroscopy, with a spectral resolution of 2.5 eV (up to 7 keV) over an hexagonal field of view of 5 arc minutes (equivalent diameter). The X-IFU entered its System Requirement Review (SRR) in June 2022, at about the same time when ESA called for an overall X-IFU redesign (including the X-IFU cryostat and the cooling chain), due to an unanticipated cost overrun of Athena. In this paper, after illustrating the breakthrough capabilities of the X-IFU, we describe the instrument as presented at its SRR, browsing through all the subsystems and associated requirements. We then show the instrument budgets, with a particular emphasis on the anticipated budgets of some of its key performance parameters. Finally we briefly discuss on the ongoing key technology demonstration activities, the calibration and the activities foreseen in the X-IFU Instrument Science Center, and touch on communication and outreach activities, the consortium organisation, and finally on the life cycle assessment of X-IFU aiming at minimising the environmental footprint, associated with the development of the instrument. Thanks to the studies conducted so far on X-IFU, it is expected that along the design-to-cost exercise requested by ESA, the X-IFU will maintain flagship capabilities in spatially resolved high resolution X-ray spectroscopy, enabling most of the original X-IFU related scientific objectives of the Athena mission to be retained. (abridged).Comment: 48 pages, 29 figures, Accepted for publication in Experimental Astronomy with minor editin

The Athena X-ray Integral Field Unit: a consolidated design for the system requirement review of the preliminary definition phase

The Athena X-ray Integral Unit (X-IFU) is the high resolution X-ray spectrometer studied since 2015 for flying in the mid-30s on the Athena space X-ray Observatory. Athena is a versatile observatory designed to address the Hot and Energetic Universe science theme, as selected in November 2013 by the Survey Science Committee. Based on a large format array of Transition Edge Sensors (TES), X-IFU aims to provide spatially resolved X-ray spectroscopy, with a spectral resolution of 2.5 eV (up to 7 keV) over a hexagonal field of view of 5 arc minutes (equivalent diameter). The X-IFU entered its System Requirement Review (SRR) in June 2022, at about the same time when ESA called for an overall X-IFU redesign (including the X-IFU cryostat and the cooling chain), due to an unanticipated cost overrun of Athena. In this paper, after illustrating the breakthrough capabilities of the X-IFU, we describe the instrument as presented at its SRR (i.e. in the course of its preliminary definition phase, so-called B1), browsing through all the subsystems and associated requirements. We then show the instrument budgets, with a particular emphasis on the anticipated budgets of some of its key performance parameters, such as the instrument efficiency, spectral resolution, energy scale knowledge, count rate capability, non X-ray background and target of opportunity efficiency. Finally, we briefly discuss the ongoing key technology demonstration activities, the calibration and the activities foreseen in the X-IFU Instrument Science Center, touch on communication and outreach activities, the consortium organisation and the life cycle assessment of X-IFU aiming at minimising the environmental footprint, associated with the development of the instrument. Thanks to the studies conducted so far on X-IFU, it is expected that along the design-to-cost exercise requested by ESA, the X-IFU will maintain flagship capabilities in spatially resolved high resolution X-ray spectroscopy, enabling most of the original X-IFU related scientific objectives of the Athena mission to be retained. The X-IFU will be provided by an international consortium led by France, The Netherlands and Italy, with ESA member state contributions from Belgium, Czech Republic, Finland, Germany, Poland, Spain, Switzerland, with additional contributions from the United States and Japan.The French contribution to X-IFU is funded by CNES, CNRS and CEA. This work has been also supported by ASI (Italian Space Agency) through the Contract 2019-27-HH.0, and by the ESA (European Space Agency) Core Technology Program (CTP) Contract No. 4000114932/15/NL/BW and the AREMBES - ESA CTP No.4000116655/16/NL/BW. This publication is part of grant RTI2018-096686-B-C21 funded by MCIN/AEI/10.13039/501100011033 and by “ERDF A way of making Europe”. This publication is part of grant RTI2018-096686-B-C21 and PID2020-115325GB-C31 funded by MCIN/AEI/10.13039/501100011033

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/)

Pierre sculptée et écrite de Ksar Sbahi (Algérie)

Février Paul-Albert, Marcillet-Jaubert Jean. Pierre sculptée et écrite de Ksar Sbahi (Algérie). In: Mélanges d'archéologie et d'histoire, tome 78, n°1, 1966. pp. 141-185

Bases et perspectives d’une évaluation formative des pratiques langagières au service de la construction des connaissances dans les disciplines scolaires

Grundlagen und Perspektiven einer formativen Evaluation der sprachlichen Tätigkeiten als Ansätze eines Aufbaus der Kenntnisse innerhalb der Schuldisziplinen, Jean-Paul Bernié, Martine Jaubert et Maryse Rebière, IUFM d’Aquitaine, université Bordeaux 2 Die zur formativen Evaluation angewendeten Verfahren weisen oft auf eine soziale Tätigkeit hin, die der innerhalb des Schulfachs, in dem die Sprachproduktion verlangt wird, geförderten Tätigkeit entgegengestzt ist. Um das ursprüngliche Ausbildungsprojekt durchzuführen, muss man auf die didaktikchen und pädagogischen Bedingungen und Zusammenhänge zurückkommen, in denen der Schüler in eine für das betroffene Schulfach stichhaltige Rednerposition versetzt wird, und man muss auch das “eventuelle Handeln” analysieren , das den interaktiven Erwerb von Kenntnissen und diskursiven Fertigkeiten dabei reguliert. Diese Art von im Verfahren eingefügter Bewertung verankert sich in der metadiskursiven Dimension von sprechlichen Austauschen, die darauf hinzielen, Verträge klarzumachen, die Rollenverteilung zu definieren, und für den Aufbau von wirksamen sprachlichen Benehmen im Rahmen einer aktiven diskursiven Gemeinschaft zu sorgen. Sie trägt auch dazu bei, Ziele und Modalitäten von spezifischen Evaluationsverfahren zu definieren, die durch die übergänglichen Sprechaktivitäten und die “ verschobenen” Situationen angedeutet werden, bei denen Alltags-und Schulrealitäten einander treffen und aneinander stoßen. Dieser Blick auf die Evaluation stellt also Fragen an die Unterrichtsverfahren des Schulfachs Französisch, denn letzteres ist für die Entwicklung einer persönlichen innerlichen wie äuBerlichen Meinung des Schülers über seine eigene Sprachtätigkeit verantwortlich.Foundations and perspectives of a formative evaluation of language practices to contribute to the construction of acqisitions in the different school subjects, Jean-Paul Bernié, Martine Jaubert et Maryse Rebière, IUFM d’Aquitaine, université Bordeaux 2 The different forms taken up by formative evaluation often reflect a social activity which is completely different from the one which is appealed to by the activity on a subject within which the linguistic activity is required. In order to achieve the initial formative project, it is necessary to reexamine the didactic and pedagogical conditions and context in which a pupil gains the posture of a relevant enunciator in one or other subject and analyse the «evolutional action» which regulates the interactive acquisition of knowledge and discursive skills. This integrated evaluation is rooted in the metadiscursive dimension of interactions aiming to clarify the contracts, favour the devolution of situations, ensure the construction of efficient postures through that of a discursive community in permanent tension. It also contributes to put forward the objectives and methods of specific evaluative practices such as what intermediate linguistic activities and «delayed » situations prefigure each in their own way, when everyday life and school life come together and clash. Therefore this look into evaluation propitiously leads to key questions on the teaching device implemented fot the French language, which can be held responsible for the construction in the pupils’ minds of both an internal and external point of view on their own linguistic activities.Les formes prises par l’évaluation formative renvoient souvent à une activité sociale en rupture avec celle qui est sollicitée par l’activité disciplinaire au sein de laquelle la production langagière est demandée. Pour accomplir le projet formatif initial, il est nécessaire de revenir aux conditions et aux contextes didactiques et pédagogiques dans lesquels l’élève conquiert une position d’énonciateur pertinent pour tel champ disciplinaire, et d’analyser «l’agir évaluationnel» qui y régule l’acquisition interactive de connaissances et de capacités discursives. Cette évaluation incorporée s’ancre dans la dimension métadiscursive d’échanges visant à clarifier les contrats, à favoriser la dévolution des situations, à assurer la construction de postures efficaces à travers celle d’une communauté discursive en tension permanente. Elle contribue également à suggérer objectifs et modalités de pratiques évaluatives spécifiques, telles que les préfigurent, chacune à leur manière, activités langagières intermédiaires et situations «différées» , où s’organisent rencontre et choc du quotidien et du scolaire. Ce regard sur l’évaluation est donc porteur de questions au dispositif disciplinaire du français, responsable de la formation chez l’élève d’un point de vue à la fois interne et extérieur sur sa propre activité langagière.Bases y perspectivas de una evaluación formativa de las prácticas de lengua al servicio de la construcción de los conocimientos dentro de las disciplinas escolares, Jean-Paul Bernié, Martine Jaubert et Maryse Rebière, IUFM d’Aquitaine, université Bordeaux 2 Las formas tomadas por la evaluación formativa remiten a menudo a una actividad social en ruptura con la que va solicitada por la actividad disciplinaria, dentro de la cual la producción del lenguaje es requerida. Para realizar el proyecto formativo inicial, es necesario volver a las condiciones y a los contextos didácticos y pedagógicos dentro de los cuales, el alumno consigue una posición enunciativa pertinente para tal sector disciplinario y entonces es necesario analizar la actuación que valoriza y regula la adquisición interactiva de conocimientos y capacidades discursivas. La incorporación de esta valorización estriba en la dimensión metadiscursiva de los intercambios, la cual pretende esclarecer los contratos, favorecer la devolución de las situaciones, asegurar la construcción de posturas eficaces entre las de una comunidad discursiva, permanentemente desarrolada. Contribuye igualmente a sugerir objetivos y modalidades de prácticas evaluativas específicas, tales como las que prefiguran, cada una a su manera, las actividades intermediarioas del lenguaje y las situaciones diferidas, donde se organizan el encuentro y el choque de lo cotidiano con lo escolar. Así, este enfoque de la evaluación está lleno de interrogantes en cuanto al dispositivo disciplinario del francés, responsable de la formación del alumno desde un punto de vista a la par interno y externo, sobre su misma actividad del lenguaje.Bernié Jean-Paul, Jaubert Martine, Rebière Maryse. Bases et perspectives d’une évaluation formative des pratiques langagières au service de la construction des connaissances dans les disciplines scolaires. In: Repères, recherches en didactique du français langue maternelle, n°31, 2005. L'évalutaion en didactique du français : résurgence d'une problématique. pp. 189-210