Interannual Dynamics of Ice Cliff Populations on Debris-Covered Glaciers From Remote Sensing Observations and Stochastic Modeling.

Ice cliffs are common on debris-covered glaciers and have relatively high melt rates due to their direct exposure to incoming radiation. Previous studies have shown that their number and relative area can change considerably from year to year, but this variability has not been explored, in part because available cliff observations are irregular. Here, we systematically mapped and tracked ice cliffs across four debris-covered glaciers in High Mountain Asia for every late ablation season from 2009 to 2019 using high-resolution multi-spectral satellite imagery. We then quantified the processes occurring at the feature scale to train a stochastic birth-death model to represent the cliff population dynamics. Our results show that while the cliff relative area can change by up to 20% from year to year, the natural long-term variability is constrained, thus defining a glacier-specific cliff carrying capacity. In a subsequent step, the inclusion of external drivers related to climate, glacier dynamics, and hydrology highlights the influence of these variables on the cliff population dynamics, which is usually not a direct one due to the complexity and interdependence of the processes taking place at the glacier surface. In some extreme cases (here, a glacier surge), these external drivers may lead to a reorganization of the cliffs at the glacier surface and a change in the natural variability. These results have implications for the melt of debris-covered glaciers, in addition to showing the high rate of changes at their surface and highlighting some of the links between cliff population and glacier state.

[Management of severe neonatal Rh disease following in utero exchange transfusion: towards a new strategy]. / Prise en charge néonatale des allo-immunisations Rhésus sévères après exsanguinotransfusion in utero: vers une nouvelle stratégie.

Important changes in the prevention, diagnosis, and in utero treatment, of Rhesus allo-immunization in the past 30 years, have led to new neonatal clinical presentations. Based upon the analysis of 14 successive pregnancies with severe hemolytic disease, requiring in utero exchange-transfusion, it appears that the current management is no longer adapted to the new resulting clinical postnatal presentations. In the acute phase, intensive phototherapy associated with regular blood cell transfusion as required, appears to be a better policy than traditional postnatal systematic exchange transfusions. In addition endogenous erythropoiesis stimulation should be included in order to avoid any unnecessary transfusion.