The Interior of Jupiter

Jupiter, owing to its large mass and rapid formation, played a crucial role in shaping the solar system as we know it today. Jupiter mostly contains hydrogen and helium (more than 87% by mass), and as such bears a close resemblance to the Sun. However, the Sun has only 2% of its mass in elements other than hydrogen and helium (the heavy elements), whereas Jupiter has between 3 and 13%. The exact amount of these heavy elements in the planet and their distribution are keys to understanding how the solar system formed

Une introduction à la nature et au fonctionnement de la physique pour des élèves de seconde.

National audienceCet article propose, décrit et justifie une séquence d'enseignement de seconde ayant pour but de profiter d'une partie du programme actuel de la classe de seconde pour proposer aux élèves une première approche de la nature et du fonctionnement de laphysique, de ses objets d'étude et de ses limites. Cette démarche, conforme aux programmes en vigueur, permet aux enseignants d'initier leurs élèves à l'activité de modélisation et de mettre en évidence sa place centrale en physique ; les élèves sont capablesde la comprendre si les enseignants prennent le temps d'expliciter les choix faits lors de cette démarche de modélisation. Les auteurs donnent aussi les points de vue, souvent proches, d'élèves de seconde et d'enseignants sur ce qu'est la physique et sur ce qu'estun modèle. Comme aboutissement de ce travail, une carte conceptuelle est proposée à l'enseignant pour permettre une analyse plus fine des démarches classiques demandées aux élèves lors de leur activité en classe de physique. L'utilisation de cette carte est illustrée sur une courte partie de la séquence proposée

Liposome retention in size exclusion chromatography

BACKGROUND: Size exclusion chromatography is the method of choice for separating free from liposome-encapsulated molecules. However, if the column is not presaturated with lipids this type of chromatography causes a significant loss of lipid material. To date, the mechanism of lipid retention is poorly understood. It has been speculated that lipid binds to the column material or the entire liposome is entrapped inside the void. RESULTS: Here we show that intact liposomes and their contents are retained in the exclusion gel. Retention depends on the pore size, the smaller the pores, the higher the retention. Retained liposomes are not tightly fixed to the beads and are slowly released from the gels upon direct or inverted eluent flow, long washing steps or column repacking. Further addition of free liposomes leads to the elution of part of the gel-trapped liposomes, showing that the retention is transitory. Trapping reversibility should be related to a mechanism of partitioning of the liposomes between the stationary phase, water-swelled polymeric gel, and the mobile aqueous phase. CONCLUSION: Retention of liposomes by size exclusion gels is a dynamic and reversible process, which should be accounted for to control lipid loss and sample contamination during chromatography

Methicillin-Resistant Staphylococcus aureus, Geneva, Switzerland, 1993–2005

Molecular characterization of methicillin-resistant Staphylococcus aureus (MRSA) strains different from those of an endemic healthcare-associated clone was conducted over 13 years in Geneva, Switzerland. We demonstrated strain diversity, including clones rarely found in Europe. Local epidemiology of community-associated MRSA is diverse and is evolving by importation and transmission of new strains

Remote monitoring of patients with implantable cardioverter-defibrillators: Can results from large clinical trials be transposed to clinical practice?

SummaryBackgroundRemote monitoring (RM) is increasingly used to follow up patients with implantable cardioverter-defibrillators (ICDs). Randomized control trials provide evidence for the benefit of this intervention, but data for RM in daily clinical practice with multiple-brands and unselected patients is lacking.AimsTo assess the effect of RM on patient management and clinical outcome for recipients of ICDs in daily practice.MethodsWe reviewed ICD recipients followed up at our institution in 2009 with RM or with traditional hospital only (HO) follow-up. We looked at the effect of RM on the number of scheduled ambulatory follow-ups and urgent unscheduled consultations, the time between onset of asymptomatic events to clinical intervention and the clinical effectiveness of all consultations. We also evaluated the proportion of RM notifications representing clinically relevant situations.ResultsWe included 355 patients retrospectively (RM: n=144, HO: n=211, 76.9% male, 60.3±15.2years old, 50.1% with ICDs for primary prevention and mean left ventricular ejection fraction 35.5±14.5%). Average follow-up was 13.5months. The RM group required less scheduled ambulatory follow-up consultations (1.8 vs. 2.1/patient/year; P<0.0001) and a far lower median time between the onset of asymptomatic events and clinical intervention (7 vs. 76days; P=0.016). Of the 784 scheduled ambulatory follow-up consultations carried out, only 152 (19.4%) resulted in therapeutic intervention or ICD reprogramming. We also found that the vast majority of RM notifications (61.9%) were of no clinical relevance.ConclusionRM allows early management of asymptomatic events and a reduction in scheduled ambulatory follow-up consultations in daily clinical practice, without compromising safety, endorsing RM as the new standard of care for ICD recipients

The SARS algorithm: detrending CoRoT light curves with Sysrem using simultaneous external parameters

Surveys for exoplanetary transits are usually limited not by photon noise but rather by the amount of red noise in their data. In particular, although the CoRoT spacebased survey data are being carefully scrutinized, significant new sources of systematic noises are still being discovered. Recently, a magnitude-dependant systematic effect was discovered in the CoRoT data by Mazeh & Guterman et al. and a phenomenological correction was proposed. Here we tie the observed effect a particular type of effect, and in the process generalize the popular Sysrem algorithm to include external parameters in a simultaneous solution with the unknown effects. We show that a post-processing scheme based on this algorithm performs well and indeed allows for the detection of new transit-like signals that were not previously detected.Comment: MNRAS accepted. 5 pages, 3 figure

EU DEMO Remote Maintenance System development during the Pre-Concept Design Phase

During the EU DEMO Pre-Concept Design Phase, the remote maintenance team developed maintenance strategies and systems to meet the evolving plant maintenance requirements. These were constrained by the proposed tokamak architecture and the challenging environments but considered a range of port layouts and handling system designs. The design-driving requirements were to have short maintenance durations and to demonstrate power plant relevant technologies. Work concentrated on the in-vessel maintenance systems, where the design constraints are the most challenging and the potential impact on the plant design is highest. A robust blanket handling system design was not identified during the Pre-Concept Design Phase. Novel enabling technologies were identified and, where these were critical to the maintenance strategy and not being pursued elsewhere, proof-of-principle designs were developed and tested. Technology development focused on pipe joining systems such as laser bore cutting and welding, pipe alignment, and on the control systems for handling massive blankets. Maintenance studies were also conducted on the ex-vessel plant to identify the additional transport volumes required to support the plant layout. The strategic implications of using vessel casks, and of using containment cells with cell casks, was explored. This was motivated by the costs associated with the storage of casks, one of several ex-vessel systems that can drive the overall plant layout. This paper introduces the remote maintenance system designs, describes the main developments and achievements, and presents conclusions, lessons learned and recommendations for future work

Au pays maya des lacs et des marais recherches archéologiques et géographiques (1999-2001)

National audienceLes sociétés mayas des hautes terres ont connu un déclin culturel marqué à la fin du Préclassique (vers 100-250 apr. JC) au moment où, pour la plupart, les cités mayas des basses terres prenaient leur essor au début du Classique (250-300 apr. J.C.). Environ 600 ans plus tard, celles du Petén (Guatemala) étaient presque toutes abandonnées alors que celles des basses terres du nord connaissaient leur apogée jusqu'au début du Postclassique. En termes géographiques, il s'agit d'analyser l'évolution d'anthropo-systèmes formés en forêt tropicale humide de mousson, soit une des rares zones où s'est développée dans le passé une civilisation puissante, agricole et urbaine sur une longue durée. Le projet Petén nord-ouest La Joyanca a pour objet l'étude d'une communauté socio-politique de rang moyen, d'époque classique, située dans une région des basses terres jusqu'à présent quasiment inconnue du point de vue archéologique. Ce projet est particulier, d'une part car il associe une approche archéologique et géographique, cherchant à restituer l'histoire des hommes en même temps que l'histoire du milieu, d'autre part parce que l'initiative de cette recherche et son financement proviennent d'une compagnie pétrolière. Ce site de la Joyanca apporte des éléments nouveaux dans le corpus des "cités" mayas classiques des basses terres du Petén : désintégration du centre politico-religieux et des ensembles de palais, association étroite au centre, dans le temps et dans l'espace, des lieux de culte et d'un grand édifice politique complexe, faible densité de l'habitat

Community-Level Responses to Iron Availability in Open Ocean Plankton Ecosystems

Predicting responses of plankton to variations in essential nutrients is hampered by limited in situ measurements, a poor understanding of community composition, and the lack of reference gene catalogs for key taxa. Iron is a key driver of plankton dynamics and, therefore, of global biogeochemical cycles and climate. To assess the impact of iron availability on plankton communities, we explored the comprehensive bio-oceanographic and bio-omics data sets from Tara Oceans in the context of the iron products from two state-of-the-art global scale biogeochemical models. We obtained novel information about adaptation and acclimation toward iron in a range of phytoplankton, including picocyanobacteria and diatoms, and identified whole subcommunities covarying with iron. Many of the observed global patterns were recapitulated in the Marquesas archipelago, where frequent plankton blooms are believed to be caused by natural iron fertilization, although they are not captured in large-scale biogeochemical models. This work provides a proof of concept that integrative analyses, spanning from genes to ecosystems and viruses to zooplankton, can disentangle the complexity of plankton communities and can lead to more accurate formulations of resource bioavailability in biogeochemical models, thus improving our understanding of plankton resilience in a changing environment