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To assess the impact of atmospheric aerosols on health, climate, and air traffic, aerosol properties must be measured with fine spatial and temporal sampling. This can be achieved by actively involving citizens and the technology they own to form an atmospheric measurement network. We establish this new measurement strategy by developing and deploying iSPEX, a low-cost, mass-producible optical add-on for smartphones with a corresponding app. The aerosol optical thickness (AOT) maps derived from iSPEX spectropolarimetric measurements of the daytime cloud-free sky by thousands of citizen scientists throughout the Netherlands are in good agreement with the spatial AOT structure derived from satellite imagery and temporal AOT variations derived from ground-based precision photometry. These maps show structures at scales of kilometers that are typical for urban air pollution, indicating the potential of iSPEX to provide information about aerosol properties at locations and at times that are not covered by current monitoring efforts.

This prospective study assesses the prevalence of intrauterine adhesions among women undergoing secondary removal of placental remnants after delivery, or a repeat curettage for incomplete abortions, and evaluates risk factors associated with the presence of intrauterine adhesions. In 50 women, undergoing either a secondary removal of placental remnants more than 24 h after delivery, or a repeat curettage for incomplete abortions, ambulatory hysteroscopy was performed 3 months after the intervention. Intrauterine adhesions were found in 20 of the women (40%): five patients had Asherman's syndrome grade I, six had grade II, six had grade III and three had grade IV. In women with menstrual disorders a statistically significant 12-fold increased risk for Asherman's syndrome grade II-IV was found. Previous abortion as well as infection during surgery were associated with a mildly but non-significant increased risk. Based on our findings, hysteroscopy is recommended only in those patients who develop menstrual disorders, either after secondary intervention for placental remnants after delivery or after a repeat curettage.

We examined the ability of seagrasses to take up dissolved organic nitrogen (DON) with leaves (in situ) and roots (laboratory) in an oligotrophic tropical offshore meadow in Indonesia using 15 N-labeled nitrogen (N) substrates. We compared the uptake of urea and amino acids with that of ammonium (NH z 4 ) and nitrate (NO { 3 ) and determined uptake kinetics of amino acids for the seagrasses Thalassia hemprichii, Halodule uninervis, and Cymodocea rotundata in comparison with the macroalgae Sargassum sp. and Padina sp. Uptake rates of small DON substrates for macroalgae were higher than those for seagrass leaves for all N substrates, but the seagrass roots also had a considerable uptake capacity. Seagrass leaves preferred urea, NH z 4 , and NO { 3 over amino acids, and there were differences between species. Seagrass roots, however, took up amino acids at rates comparable to NH z 4 , whereas uptake rates of urea and NO { 3 were much lower. The ability to take up DON enables seagrasses and macroalgae to shortcut N cycling and gives them access to additional N resources. In oligotrophic environments, uptake of amino acids by roots may provide seagrasses with a competitive advantage over macroalgae.