Dust traps in the protoplanetary disc MWC 758: two vortices produced by two giant planets?

Resolved ALMA and VLA observations indicate the existence of two dust traps in the protoplanetary disc MWC 758. By means of 2D gas+dust hydrodynamical simulations post-processed with 3D dust radiative transfer calculations, we show that the spirals in scattered light, the eccentric, asymmetric ring and the crescent-shaped structure in the (sub)millimetre can all be caused by two giant planets: a 1.5-Jupiter mass planet at 35 au (inside the spirals) and a 5-Jupiter mass planet at 140 au (outside the spirals). The outer planet forms a dust-trapping vortex at the inner edge of its gap (at ~85 au), and the continuum emission of this dust trap reproduces the ALMA and VLA observations well. The outer planet triggers several spiral arms which are similar to those observed in polarised scattered light. The inner planet also forms a vortex at the outer edge of its gap (at ~50 au), but it decays faster than the vortex induced by the outer planet, as a result of the disc's turbulent viscosity. The vortex decay can explain the eccentric inner ring seen with ALMA as well as the low signal and larger azimuthal spread of this dust trap in VLA observations. Finding the thermal and kinematic signatures of both giant planets could verify the proposed scenario.Comment: 18 pages, 8 figures, accepted for publication in MNRA

Dust traps in the protoplanetary disc MWC 758: two vortices produced by two giant planets?

International audienc

Cm-wavelength observations of MWC 758: resolved dust trapping in a vortex

International audienc

L’histoire des disciplines : un champ de recherche en mutation

Trente ans après la publication par André Chervel d’un article novateur sur l’histoire des disciplines scolaires, ce dossier veut mettre en perspective les mutations et les tendances actuelles de ce champ de recherche, aujourd’hui marqué par un intérêt croissant pour les acteurs, c’est-à-dire pour ceux qui « produisent » les disciplines. Il cherche à expliciter les aspects épistémologiques et méthodologiques de cette évolution, en la resituant dans le champ, plus large de la recherche sur les contenus d’enseignement. L’introduction pose donc, sur cet objet précis, la question d’une spécificité de l’approche historique sur les phénomènes éducatifs, par rapport aux regards croisés des autres sciences humaines et sociales. Portant sur l’enseignement secondaire (puis du second degré) français au XXe siècle, le dossier articule ainsi perspectives disciplinaires et perspectives curriculaires. Il s’attache à mettre en lumière la multiplicité des acteurs impliqués dans la fabrication comme dans l’organisation des disciplines ou des champs disciplinaires, depuis les enseignants de terrain jusqu’aux cabinets ministériels, ainsi que la variété de leurs actions, individuelles ou collectives. Il met plus particulièrement l’accent sur le rôle des enseignants dans la définition des contenus d’enseignement comme dans l’affirmation de la légitimité de leurs disciplines dans le champ scolaire. Thirty years after André Chervel’s innovative article on the history of school subjects, this special issue aims to put into perspective the recent changes and trends in this field of research, which is now characterised by a growing interest in actors, i.e. those who "produce" the disciplines. It seeks to clarify the epistemological and methodological aspects of this evolution, resituating it in the broader field of research on curriculum and teaching content. The introduction thus questions the specificity of French historical scholarship in this research field, compared with the contributions of other disciplinary approaches, in France and abroad. Focusing on French post-elementary and secondary education in the 20th century, the special issue combines disciplinary and curricular perspectives. It seeks to highlight the multiplicity of actors involved in the design and organisation of school subjects or disciplinary fields - from practising teachers to minister’s advisers - as well as their different actions, both individual and collective. It places particular emphasis on the role of teachers in developing curricula and in asserting the legitimacy of their subjects in the school arena

PRADOC: a trial on the efficiency of a transition care management plan for hospitalized patients with heart failure in France

International audienceAims: Transition care programmes are designed to improve coordination of care between hospital and home. For heart failure patients, meta-analyses show a high efficacy but with moderate evidence level. Moreover, difficulties for implementation of such programmes limit their extrapolation.Methods and results: We designed a mixed-method study to assess the implementation of the PRADO-IC, a nationwide transition programme that aims to be offered to every patient with heart failure in France. This programme consists essentially in an administrative assistance to schedule follow-up visits and in a nurse follow-up during 2 to 6 months and aims to reduce the annual heart failure readmission rate by 30%. This study assessed three quantitative aims: the cost to avoid a readmission for heart failure within 1 year (primary aim, intended sample size 404 patients), clinical care pathways, and system economic outcomes; and two qualitative aims: perceived problems and benefits of the PRADO-IC. All analyses will be gathered at the end of study for a joint interpretation. Strengths of this study design are the randomized controlled design, the population included in six centres with low motivation bias, the primary efficiency analysis, the secondary efficacy analyses on care pathway and clinical outcomes, and the joint qualitative analysis. Limits are the heterogeneity of centres and of intervention in a control group and parallel development of other new therapeutic interventions in this field.Conclusions: The results of this study may help decision-makers to support an administratively managed transition programme

CdSe quantum dot-sensitized solar cells exceeding efficiency 1% at full-sun intensity

Colloidal cadmium selenide (CdSe) quantum dots QDs) have been prepared and exploited as inorganic dyes to sensitize a large-band-gap TiO2 layer for QD-sensitized solar cells. The optimized QD-sensitized solar cells exhibited an unprecedented incident photon-to-charge carrier generation efficiency of 36% and an overall conversion efficiency of over 1.7% at 0.1 sun and 1% at full sun intensity with a cobalt(II/III)-based redox system. The photovoltaic characteristics of CdSe QD-sensitized cells are compared with standard dye-sensitized solar cells, in which the former exhibited about half of the efficiency of the latter. From the kinetics of charge transfer monitored using transient spectroscopic and voltage decay measurements in the CdSe QD-sensitized cell, the regeneration yield of oxidized QDs was found to be close to almost unity, and the electron lifetime was longer in the CdSe QD-sensitized cell than in the dye-sensitized solar cellclose26

Science and technology roadmap for graphene, related two-dimensional crystals, and hybrid systems

We present the science and technology roadmap for graphene, related two-dimensional crystals, and hybrid systems, targeting an evolution in technology, that might lead to impacts and benefits reaching into most areas of society. This roadmap was developed within the framework of the European Graphene Flagship and outlines the main targets and research areas as best understood at the start of this ambitious project. We provide an overview of the key aspects of graphene and related materials (GRMs), ranging from fundamental research challenges to a variety of applications in a large number of sectors, highlighting the steps necessary to take GRMs from a state of raw potential to a point where they might revolutionize multiple industries. We also define an extensive list of acronyms in an effort to standardize the nomenclature in this emerging field