Linear stability analysis of transverse dunes

Sand-moving winds blowing from a constant direction in an area of high sand availability form transverse dunes, which have a fixed profile in the direction orthogonal to the wind. Here we show, by means of a linear stability analysis, that transverse dunes are intrinsically unstable. Any along-axis perturbation on a transverse dune amplify in the course of dune migration due to the combined effect of two main factors, namely: the lateral transport through avalanches along the dune's slip-face, and the scaling of dune migration velocity with the inverse of the dune height. Our calculations provide a quantitative explanation for recent observations from experiments and numerical simulations, which showed that transverse dunes moving on the bedrock cannot exist in a stable form and decay into a chain of crescent-shaped barchans.Comment: 8 pages, 4 figure

Rings in the Solar System: a short review

Rings are ubiquitous around giant planets in our Solar System. They evolve jointly with the nearby satellite system. They could form either during the giant planet formation process or much later, as a result of large scale dynamical instabilities either in the local satellite system, or at the planetary scale. We review here the main characteristics of rings in our solar system, and discuss their main evolution processes and possible origin. We also discuss the recent discovery of rings around small bodies.Comment: Accepted for the Handbook of Exoplanet

The multifaceted nature of diabetes mellitus induced by checkpoint inhibitors

Immune checkpoint inhibitors (CPI) are increasingly being used in oncology, and many autoimmune side effects have been described. Diabetes mellitus (DM) has been reported in approximately 1% of subjects treated with programmed cell death-1 and programmed death ligand 1 (PD-1/PD-L1) inhibitors, alone or in association with CTLA-4 inhibitors. In the present mini-review, we aimed to describe different clinical pictures and pathophysiology associated with these forms of diabetes. Data on CPI-related DM was gathered from the largest case series in the literature and from our centre dedicated to immunotherapy complications (ImmuCare-Hospices Civils de Lyon). Most cases are acute autoimmune insulin-dependent diabetes which are similar to fulminant diabetes (extremely acute onset with concomitant near-normal HbA1c levels). Other cases, however, have a phenotype close to type 2 diabetes or appear as a decompensation of previously known type 2 diabetes. The occurrence of diabetes can also be a complication of autoimmune pancreatitis induced by CPI use. Finally, two cases of diabetes in a context of autoimmune lipoatrophy have recently been described. Regarding the wide variety of CPI-induced diabetes, the discovery of a glucose disorder under CPI should motivate specialised care for aetiological diagnosis and appropriate treatment

Diabetes mellitus induced by PD-1 and PD-L1 inhibitors: description of pancreatic endocrine and exocrine phenotype

AIMS: Programmed cell death-1 and programmed death ligand 1 (PD-1/PD-L1) inhibitors restore antitumor immunity, but many autoimmune side-effects have been described. Diabetes mellitus is a rare complication, and little data concerning its pathophysiology and phenotype have been published. This study aimed to describe both pancreatic endocrine and exocrine functions, immunological features and change in pancreas volume in subjects with diabetes mellitus induced by PD-1 and PD-L1 inhibitors. METHODS: We analyzed the data of six subjects treated with immunotherapy who presented acute diabetes. RESULTS: There were five men and one woman. Median age was 67 years (range 55-83). Three subjects were treated with nivolumab, two with pembrolizumab and one with durvalumab. Median time to diabetes onset after immunotherapy initiation was 4 months (range 2-13). Four patients presented fulminant diabetes (FD); none of these had type 1 diabetes (T1D)-related autoantibodies, none of them had T1D or FD-very high-risk HLA class II profiles. The bi-hormonal endocrine and exocrine pancreatic failure previously reported for one FD patient was not found in other FD subjects, but glucagon response was blunted in another FD patient. Pancreas volume was decreased at diabetes onset in 2 FD patients, and all patients presented a subsequent decrease of pancreas volume during follow-up. CONCLUSIONS: In the patients presented herein, immunotherapy-induced diabetes was not associated with T1D-related autoantibodies. The hormonal and morphological analysis of the pancreatic glands of these six cases contributes to the understanding of the underlying and probably heterogeneous mechanisms. There is a need to find biomarkers to identify patients at risk to develop these new forms of diabetes at early stages of the process to prevent ketoacidosis and to evaluate preventive strategies

Titan's Longitudinal Dunes in the Lab.

International audienc

Titan's Longitudinal Dunes in the Lab.

International audienc

Titan's Longitudinal Dunes in the Lab.

International audienc