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http://dx.doi.org/10.1038/472048a | DOI Listing |
Chaos
January 2025
Institute for Theoretical Physics, University of Leipzig, D-04081 Leipzig, Germany.
We consider a dynamical system undergoing a saddle-node bifurcation with an explicitly time-dependent parameter p(t). The combined dynamics can be considered a dynamical system where p is a slowly evolving parameter. Here, we investigate settings where the parameter features an overshoot.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
February 2025
Department of Psychology, University of Potsdam, Potsdam 14476, Germany.
Measurement literacy is required for strong scientific reasoning, effective experimental design, conceptual and empirical validation of measurement quantities, and the intelligible interpretation of error in theory construction. This discourse examines how issues in measurement are posed and resolved and addresses potential misunderstandings. Examples drawn from across the sciences are used to show that measurement literacy promotes the goals of scientific discourse and provides the necessary foundation for carving out perspectives and carrying out interventions in science.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
February 2025
Department of Marine Microbiology and Biogeochemistry, Royal Netherlands Institute for Sea Research (NIOZ), Den Burg 1790 AB, The Netherlands.
Heterocytes, specialized cells for nitrogen fixation in cyanobacteria, are surrounded by heterocyte glycolipids (HGs), which contribute to protection of the nitrogenase enzyme from oxygen. Diverse HGs preserve in the sediment and have been widely used as evidence of past nitrogen fixation, and structural variation has been suggested to preserve taxonomic information and reflect paleoenvironmental conditions. Here, by comprehensive HG identification and screening of HG biosynthetic gene clusters throughout cyanobacteria, we reconstruct the convergent evolutionary history of HG structure, in which different clades produce the same HGs.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
February 2025
Department of Earth System Sciences, Center for Earth System Research and Sustainability, University of Hamburg, Hamburg 20146, Germany.
As an essential micronutrient, phosphorus plays a key role in oceanic biogeochemistry, with its cycling intimately connected to the global carbon cycle and climate change. Authigenic carbonate fluorapatite (CFA) has been suggested to represent a significant phosphorus sink in the deep ocean, but its formation mechanisms in oceanic low-productivity settings remain poorly constrained. Applying X-ray absorption near edge structure, transmission electron microscopy, and laser ablation inductively coupled plasma mass spectrometer analyses, we report a unique mineral assemblage where CFA crystals coat phillipsite in abyssal sediments of the East Mariana Basin and the Philippine Sea.
View Article and Find Full Text PDFISME J
January 2025
Australian Antarctic Program Partnership (AAPP), Institute for Marine and Antarctic Studies, University of Tasmania, 20 Castray Esplanade, Battery Point, TAS, 7004, Australia.
Iron plays a pivotal role in regulating ocean primary productivity. Iron is supplied from diverse sources such as the atmosphere and the geosphere, and hence iron biogeochemical research has focused on identifying and quantifying such sources of "new" iron. However, the recycling of this new iron fuels up to 90% of the productivity in vast oceanic regions.
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