The Ionospheric Connection Explorer - Prime Mission Review.

The two-year prime mission of the NASA Ionospheric Connection Explorer (ICON) is complete. The baseline operational and scientific objectives have been met and exceeded, as detailed in this report. In October of 2019, ICON was launched into an orbit that provides its instruments the capability to deliver near-continuous measurements of the densest plasma in Earth's space environment. Through collection of a key set of in-situ and remote sensing measurements that are, by virtue of a detailed mission design, uniquely synergistic, ICON enables completely new investigations of the mechanisms that control the behavior of the ionosphere-thermosphere system under both geomagnetically quiet and active conditions. In a two-year period that included a deep solar minimum, ICON has elucidated a number of remarkable effects in the ionosphere attributable to energetic inputs from the lower and middle atmosphere, and shown how these are transmitted from the edge of space to the peak of plasma density above. The observatory operated in a period of low activity for 2 years and then for a year with increasing solar activity, observing the changing balance of the impacts of lower and upper atmospheric drivers on the ionosphere.

Identifying proxies and mapping heavy metals concentrations in city road dusts: A case study in the Brussels-Capital Region, Belgium.

This paper investigates the spatial distribution of heavy metals (HMs) concentrations in road dusts over a part of the Brussels-Capital Region (BCR), with the aim of identifying the most relevant factors impacting these concentrations and subsequently mapping them over all road segments. For this goal, a set of 128 samples of road dusts was collected over a three years time span in the Anderlecht municipality, that covers about a tenth of the BCR area. The concentrations of Cd, Cr, Cu, Ni, Pb and Zn have been measured in the finest fraction ( ⌀ < 250 µm) using ICP-OES. In parallel, continuous and categorical-valued proxies have been collected over all road segments. Using a multivariate linear modeling (MLR) approach, the most influential proxies that have been identified are the distance to the center of the BCR, land use, road hierarchy and roadside parking occupation. The performance of the MLR models remains however limited, with adjusted R 2 values around 0.5 for all HMs. From a spatial analysis of the regression residuals, it is likely that some useful proxies could have been overlooked. Although these models have clear limitations for reliably predicting HMs concentrations at specific locations, the corresponding maps drawn over all road segments provide a useful overview and help designing sound monitoring policies as well appropriate implementation of mitigation measures at places where road dust pollutants tend to concentrate. Further studies are needed to confirm this, but it is expected that our models will perform reasonably well over a large part of the BCR. It is believed too that our findings are relevant for modeling road dusts pollution in other cities as well.

First fossil record of parasitism in Devonian calcareous sponges (stromatoporoids).

INTRODUCTION: Palaeozoic calcareous sponges (stromatoporoids) are common bio-constructing fossils; they are sometimes found in association with helicoidal structures of unknown biological affinities. The interaction between the tube-forming organisms has usually been classified as commensalism. METHODS: About 260 stromatoporoid skeletons from the Middle Devonian (Givetian) of the Mont d'Haurs section near Givet (Champagne-Ardenne, France) were thin-sectioned and analysed under transmitted light. RESULTS: Approximately 10% of the examined stromatoporoids (mainly belonging to the genera Actinostroma, Stromatopora and Stromatoporella) contain tubes classified as Torquaysalpinx sp. The Torquaysalpinx organisms penetrated the skeletons of stromatoporoids in vivo (as evidenced by skeletal overgrowths); around the infesting organisms, growth bands are bent down. CONCLUSION: Diminished growth rates around the infesting organism demonstrate a negative influence on the host, similar to that seen in the modern demosponge-polychaete association of Verongia-Haplosyllis. This is demonstrated by changes in growth bands. As in the above-mentioned association, the endosymbiont might have been feeding directly upon the tissues of the host. The Torquaysalpinx organisms were gaining habitat and possibly also food resources - for them this interaction was clearly positive. This long-term association can therefore be classified as parasitism. This is the first evidence for parasitism in Palaeozoic sponges.