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Dissolved organic carbon (DOC) released by macroalgae is important in the context of coral reef degradation as it contributes to coral mortality via promoting bacterial metabolism on the coral surface. Using experimental carbon dioxide (CO2 ) manipulations in outdoor flow-through tanks, we found that seawater CO2 enrichment enhances daily net DOC release in a range of macroalgal species in the Great Barrier Reef (Australia). There was however, large variability in DOC release among species, light and dark conditions, and CO2 exposure times. Under light conditions, DOC release in the red macroalga Amansia was 15 times higher under high CO2 conditions compared to ambient CO2 , however, CO2 enhancement did not affect DOC production in the other species. Results from the night incubations were more consistent as three of the four species (Amansia, Lobophora, and Sargassum) enhanced DOC release when enriched with CO2 . DOC fluxes shifted from production in the 1-d incubations to consumption in the 19-d experiment under light conditions, suggesting an important role of bacteria in DOC balances. The results suggest that rising CO2 (and ocean acidification) will continue to intensify space competition in favour of the macroalgae, potentially exacerbating reef degradation and ecological phase shifts from coral to macroalgal dominance. This article is protected by copyright. All rights reserved.In nitrogen (N)-limited boreal forests, trees depend on the decomposing activity of their ectomycorrhizal (ECM) fungal symbionts to access soil N. A large fraction of this N exists as proteinaceous compounds associated with mineral particles. However, it is not known if ECM fungi can access these mineral-associated proteins; accordingly possible acquisition mechanisms have not been investigated. With tightly controlled isotopic, spectroscopic and chromatographic experiments, we quantified and analyzed the mechanisms of N acquisition from iron oxide mineral-associated proteins by Paxillus involutus, a widespread ECM fungus in boreal forests. The fungus acquired N from the mineral-associated proteins. The collective results indicated a proteolytic mechanism involving formation of the crucial enzyme-substrate complexes at the mineral surfaces. Hence, the enzymes hydrolyzed the mineral-associated proteins without initial desorption of the proteins. The proteolytic activity was suppressed by adsorption of proteases to the mineral particles. This process was counteracted by fungal secretion of mineral-surface-reactive compounds that decreased the protease-mineral interactions and thereby promoted the formation of enzyme-substrate complexes. The ability of ECM fungi to simultaneously generate extracellular proteases and surface-reactive metabolites suggests that they can play an important role in un-locking the large N pool of mineral-associated proteins to trees in boreal forests. This article is protected by copyright. All rights reserved.Prestigious University is a large, private educational institution with a medical school, a university hospital, a law school, and graduate and undergraduate colleges all on a single campus. In the face of the Covid-19 pandemic, students were told during spring break to return to campus only briefly to retrieve their belongings. Classes then went online. On March 23, 2020, the faculty, students, and staff were emailed the following by the university's director of infection control and public health We have become aware that a Prestigious University staff member has tested positive for the virus that causes Covid-19. The individual, who was last on campus on March 16, is now in isolation at their permanent residence and is doing well clinically. The university has already identified those members of our community who may have been in close contact with this individual, and we are working to notify them. Further, this individual's local health department has a protocol for identifying people who have been in direct contact with anyone testing positive for Covid-19 (such as this Prestigious University staff member) so that they can self-quarantine and watch for COVID-19 symptoms for a period of 14 days from their last contact with the infected individual. A professor in the Philosophy Department has asked the ethicists at the medical school whether such contact tracing suffices. Divarasib mouse "Don't the members of the community deserve to know who this is? Isn't there a mandate to identify this person in order to maximize public health benefits and slow the spread of this deadly virus?" © 2020 The Hastings Center.PURPOSE To develop a magnetic resonance (MR)-based method for estimation of continuous linear attenuation coefficients (LAC) in positron emission tomography (PET) using a physical compartmental model and ultrashort echo time (UTE)/multi-echo Dixon (mUTE) acquisitions. METHODS We propose a three-dimensional (3D) mUTE sequence to acquire signals from water, fat, and short-T2 components (e.g., bones) simultaneously in a single acquisition. The proposed mUTE sequence integrates 3D UTE with multi-echo Dixon acquisitions and uses sparse radial trajectories to accelerate imaging speed. Errors in the radial k-space trajectories are measured using a special k-space trajectory mapping sequence and corrected for image reconstruction. A physical compartmental model is used to fit the measured multi-echo MR signals to obtain fractions of water, fat and bone components for each voxel, which are then used to estimate the continuous LAC map for PET attenuation correction. RESULTS The performance of the proposed method was evaluated via phantom and in vivo human studies, using LACs from Computed Tomography (CT) as reference. Compared to Dixon- and atlas-based MRAC methods, the proposed method yielded PET images with higher correlation and similarity in relation to the reference. The relative absolute errors of PET activity values reconstructed by the proposed method were below 5% in all of the four lobes (frontal, temporal, parietal, occipital), cerebellum, whole white matter and gray matter regions across all subjects (n=6). CONCLUSIONS The proposed mUTE method can generate subject-specific, continuous LAC map for PET attenuation correction in PET/MR. This article is protected by copyright. All rights reserved.