28 research outputs found

    Carbon sequestration in the deep Atlantic enhanced by Saharan dust

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    Enhanced atmospheric input of dust-borne nutrients and minerals to the remote surface ocean can potentially increase carbon uptake and sequestration at depth. Nutrients can enhance primary productivity, and mineral particles act as ballast, increasing sinking rates of particulate organic matter. Here we present a two-year time series of sediment trap observations of particulate organic carbon flux to 3,000‚ÄČm depth, measured directly in two locations: the dust-rich central North Atlantic gyre and the dust-poor South Atlantic gyre. We find that carbon fluxes are twice as high and a higher proportion of primary production is exported to depth in the dust-rich North Atlantic gyre. Low stable nitrogen isotope ratios suggest that high fluxes result from the stimulation of nitrogen fixation and productivity following the deposition of dust-borne nutrients. Sediment traps in the northern gyre also collected intact colonies of nitrogen-fixing Trichodesmium species. Whereas ballast in the southern gyre is predominantly biogenic, dust-derived mineral particles constitute the dominant ballast element during the enhanced carbon fluxes in the northern gyre. We conclude that dust deposition increases carbon sequestration in the North Atlantic gyre through the fertilization of the nitrogen-fixing community in surface waters and mineral ballasting of sinking particles

    The genetic architecture of the human cerebral cortex

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    The cerebral cortex underlies our complex cognitive capabilities, yet little is known about the specific genetic loci that influence human cortical structure. To identify genetic variants that affect cortical structure, we conducted a genome-wide association meta-analysis of brain magnetic resonance imaging data from 51,665 individuals. We analyzed the surface area and average thickness of the whole cortex and 34 regions with known functional specializations. We identified 199 significant loci and found significant enrichment for loci influencing total surface area within regulatory elements that are active during prenatal cortical development, supporting the radial unit hypothesis. Loci that affect regional surface area cluster near genes in Wnt signaling pathways, which influence progenitor expansion and areal identity. Variation in cortical structure is genetically correlated with cognitive function, Parkinson's disease, insomnia, depression, neuroticism, and attention deficit hyperactivity disorder

    Prediction of Neutropenic Events in Chemotherapy Patients: A Machine Learning Approach

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    PURPOSE Severe and febrile neutropenia present serious hazards to patients with cancer undergoing chemotherapy. We seek to develop a machine learning‚Äďbased neutropenia prediction model that can be used to assess risk at the initiation of a chemotherapy cycle. MATERIALS AND METHODS We leverage rich electronic medical records (EMRs) data from a large health care system and apply machine learning methods to predict severe and febrile neutropenic events. We outline the data curation process and challenges posed by EMRs data. We explore a range of algorithms with an emphasis on model interpretability and ease of use in a clinical setting. RESULTS Our final proposed model demonstrates an out-of-sample area under the receiver operating characteristic curve of 0.865 (95% CI, 0.830 to 0.891) in the prediction of neutropenic events on the basis of only 20 clinical features. The model validates known risk factors and offers insight into potential novel clinical indicators and treatment characteristics that elevate risk. It relies on factors that are directly extractable from EMRs, provided a tool can be easily integrated into existing workflows. A cost-based analysis provides insight into optimal risk thresholds and offers a framework for tailoring algorithms to individual hospital needs. CONCLUSION A better understanding of neutropenic risk on an individual level enables a more informed approach to patient monitoring and treatment decisions. </jats:sec