Refurbishing Voyager 1 & 2 Planetary Radio Astronomy (PRA) Data

Voyager/PRA (Planetary Radio Astronomy) data from digitized tapes archived at CNES have been reprocessed and recalibrated. The data cover the Jupiter and Saturn flybys of both Voyager probes. We have also reconstructed goniopolarimetric datasets (flux and polarization) at full resolution. These datasets are currently not available to the scientific community, but they are of primary interest for the analysis of the Cassini data at Saturn, and the Juno data at Jupiter, as well as for the preparation of the JUICE mission. We present the first results derived from the re-analysis of this dataset.Comment: Accepted manuscript for PRE8 (Planetary Radio Emission VIII conference) proceeding

Self-oscillation and Synchronisation Transitions in Elasto-Active Structures

The interplay between activity and elasticity often found in active and living systems triggers a plethora of autonomous behaviors ranging from self-assembly and collective motion to actuation. Amongst these, spontaneous self-oscillations of mechanical structures is perhaps the simplest and most wide-spread type of non-equilibrium phenomenon. Yet, we lack experimental model systems to investigate the various dynamical phenomena that may appear. Here, we report self-oscillation and synchronization transitions in a centimeter-sized model system for one-dimensional elasto-active structures. By combining precision-desktop experiments of elastically coupled self-propelled particles with numerical simulations and analytical perturbative theory, we demonstrate that the dynamics of single chain follows a Hopf bifurcation. We show that this instability is controlled by a single non-dimensional elasto-active number that quantifies the interplay between activity and elasticity. Finally, we demonstrate that pairs of coupled elasto-active chains can undergo a synchronization transition: the oscillations phases of both chains lock when the coupling link is sufficiently stiff. Beyond the canonical case considered here, we anticipate our work to open avenues for the understanding and design of the self-organisation and response of active artificial and biological solids, e.g. in higher dimensions and for more intricate geometries

Testing the relationship between Saturn's ENA and narrowband radio emissions

Saturn’s kilometric radiation (SKR) and Energetic Neutral Atom (ENA) emissions are important remote diagnostics of the planet’s magnetospheric dynamics, intensifying during periods of global-scale plasma injection, and displaying characteristic planetary periodicity. Global-scale ENA signatures have been associated with narrowband radio emissions around 5 and 20 kHz, particularly at evening local times where plasma injections are expected to have moved inwards through the magnetosphere, triggering interchange instabilities. Narrowband radio emission sources are associated with density gradients at the inner edges of the Enceladus plasma torus that promote wave mode conversion, but any radial distance dependence with the ENA emission is untested. We constrain ENA keograms to distances covering the ‘inner’ and ‘outer’ magnetosphere separately, and quantify the correlation between the ENA intensity with narrowband flux density in the 5 and 20 kHz emission bands. One case study shows a spiral ENA morphology that indicates global-scale plasma injection activity. ‘Bursts’ of narrowband emission coincide with the rotation of ENA enhancements through the dusk-midnight local time sector in the inner magnetosphere, but at earlier times in the outer magnetosphere, consistent with inward flow of the injected plasma as it drifts around the planet. A second case study with similar observing conditions shows clear 5 kHz radio bursts, but very low levels of ENA detections, indicating that the relationship is not always so general in these data. These results contribute towards our developing picture of how global plasma injection events can influence Saturn’s inner magnetosphere, linking together two valuable sources of remotely sensed global emissions, the ENAs and narrowband radio emissions

Fine structures of radio bursts from flare star AD Leo with FAST observations

Radio bursts from nearby active M-dwarfs have been frequently reported and extensively studied in solar or planetary paradigms. Whereas, their sub-structures or fine structures remain rarely explored despite their potential significance in diagnosing the plasma and magnetic field properties of the star. Such studies in the past have been limited by the sensitivity of radio telescopes. Here we report the inspiring results from the high time-resolution observations of a known flare star AD Leo with the Five-hundred-meter Aperture Spherical radio Telescope (FAST). We detected many radio bursts in the two days of observations with fine structures in the form of numerous millisecond-scale sub-bursts. Sub-bursts on the first day display stripe-like shapes with nearly uniform frequency drift rates, which are possibly stellar analogs to Jovian S-bursts. Sub-bursts on the second day, however, reveal a different blob-like shape with random occurrence patterns and are akin to solar radio spikes. The new observational results suggest that the intense emission from AD Leo is driven by electron cyclotron maser instability which may be related to stellar flares or interactions with a planetary companion.Comment: 25 pages, 12 figures, accepted for publication in Ap

Impact des organokines dans l'insuffisance rénale induite par l'obésité

The growing increase of obesity intensifies the incidence of chronic kidney disease (CKD) across the world. We previously showed that AMP-activated protein kinase (AMPK) plays a critical role in regulating the chronic cellular response to lipid excess. Indeed, we established that high-fat diet (HFD)-induced kidney disease is characterized by renal hypertrophy, increased albuminuria and elevated markers of renal fibrosis and inflammation while these HFD-induced markers were reversed by pharmacological AMPK activation. In addition, we also showed that HFD alters lipid metabolism, leading to lipid accumulation in the kidney. While these features were highlighted in male mice, we recently demonstrated that female mice are protected from disturbed renal lipid metabolism. Indeed, lipidomic analysis revealed a significant increase in ceramide and phospholipids species in HFD-fed mice but not in HFD-fed female. Interestingly, these results were associated to a sustained plasma adiponectin level and renal AMPK activity (Juszczak et al., 2023). Therefore, to better understand the organ crosstalk during obesity-induced kidney disease, different organokines will be analyzed. Organokines like myokines, adipokines, hepatokines are peptides released in the blood by different organs (muscle, adipose tissue or liver respectively). Organokines may impact entire body metabolism and by extension renal function. In an obesity context, adipokine production variates leading to metabolic perturbation to other organs. Consequently, these latter will have an alteration of their organokine production leading to global organ cross talk disturbance. Here, we will characterize the organokines produced in male and female lean and obese mice and investigate their impact on the AMPK activity and renal lipotoxicity in primary proximal tubular epithelial cells. To do so, blood organokine levels are studied thank to Multiple Reaction Monitoring - Mass Spectrometry (MRM-MS) (MS-QUANTA, Bioprofiling platform, UMONS) and correlations are carried out with metabolic and renal function readouts. Up to now, adiponectin, leptin and adipsin are analyzed in MRM MS. First of all, serum organokine levels were analyzed in lean female and male mice with MRM-MS. Serum adiponectin level was significantly higher in female compared to male (Figure 1A). However, leptin and adipsin levels did not show any difference (Figures 1B and 1C-1). Thereafter, mice were fed with HFD and low-fat diet (LFD) for 20 weeks. Only adipsin level was reduced in obese male mice compared to lean male (Figure 1C-2). Currently, more analyzes are performing in HFD fed female mice, on kidney injury markers and on renal lipid metabolism to perform correlation with organokine level. Our principal objective is to develop organokine dosage method based on MRM-MS which is cheaper and more sensitive than antibody-based methods. This approach will be further developed in clinical studies in order to better understand organ cross talk mechanism notably in obesity induced CKD. This method aims to determine other potential biomarkers and to help therapeutic strategy

Autonomous navigation system for free floating experiments in parabolic flights

This paper presents the development of an Extended Kalman Filter for the navigation system of a spacecraft in a parabolic flight. The algorithm blends the measurements coming from two Inertia Measurement Units, one mounted on the spacecraft and one on the baseplate of the aircraft; and a camera system connected to the baseplate as well. During the zero-g phases the attitude and position of the spacecraft in the experimental area are recovered thanks to a series of Alvar markers attached on the spacecraft casing and detected by the camera system. Results from parabolic test campaign of October 2019 are finally presented

Ultrasound assessments of organs and blood vessels before and after 40 days isolation in a cavern (deep time experiment 2021)

Introduction: Spaceflight simulation studies like confinement in small volume habitat with limited physical activity have reported even after 60 days an abnormal arterial wall adaptation with increase thickness or stiffness. The purpose of the current study was to determine the effects on blood vessel and organ structure of 40 days of isolation in a huge habitat with intensive physical activity.Method: Data were collected from 14 individuals (7 male) who isolated in a cavern for 40-days while performing normal daily activities without time references. Ultrasound assessments were performed pre- and post-isolation using a teleoperated system with eight different acoustic windows to obtain 19 measurements on 12 different organ/vascular structures which included the common carotid artery, femoral artery, tibial artery, jugular vein, portal vein, bile duct, kidney, pancreas, abdominal aorta, cervical and lumbar vertebral distance, and Achilles tendon.Results: Common carotid artery measures, including the intima media thickness, stiffness index, and the index of reflectivity measured from the radiofrequency signal, were not changed with isolation. Similarly, no differences were found for femoral artery measurements or measurements of any of the other organs/vessels assessed. There were no sex differences for any of the assessments.Discussion: Results from this study indicate a lack of physiological effects of 40-days of isolation in a cavern, contrary to what observed in previous 60 days confinement. This suggests a potential protective effect of sustained physical activity, or reduced environmental stress inside the huge volume of the confined facility

Ponts mixtes bois béton collés: Etude de l’interface sous chargement thermo-hygromécanique

Dans ce papier sont présentés les premiers résultats d’une étude globale visant à consolider, puis proposer des règles de dimensionnement de ponts mixtes bois / béton collés. La liaison collée est explorée de manière expérimentale avec des essais de cisaillement utilisant du lamellé collé et du LVL. Afin d’anticiper le vieillissement de cette liaison, des essais ont été réalisés à différentes humidités. Dans une deuxième partie, le développement d’outils de simulation par éléments finis est présenté. La modélisation thermo-hydrique est appliquée sur des temps longs à des sections correspondant aux nervures bois d’un pont. Les phénomènes mécaniques à prendre en compte sont listés.Conseil Régional Bourgogne Franche-Comt