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Not AvailableMethane emissions from Kentucky underground coal mines were measured using near-infrared spectrometers deployed on a vehicle, an airplane, and a small uncrewed aerial system (sUAS), offering insights into the effectiveness of these methods under real-world conditions. From 2021–2022, surveys covered 14 active, 4 inactive, and 4 abandoned mines across Kentucky’s coal-producing basins. Vehicle-based surveys at 13 active mines detected methane anomalies at 9 sites with anomaly lengths spanning tens to hundreds of meters and peak emissions of 665 ± 229 kg h–1 from two Cardinal mine fans. Airborne GHGSat surveys identified anomalies at 3 sites, including a peak of 1062 ± 386 kg h–1 at Cardinal, consistent with the EPA’s Greenhouse Gas Reporting Program (GHGRP) ranges. sUAS emissions measured at Straight Creek were 65 ± 22 kg h–1 (below the GHGRP reporting threshold). Aeris vehicle-based estimates more closely matched GHGRP values than GHGSat estimates and exhibited smaller uncertainties. For example, at Cardinal Nebo, Aeris reported 228 ± 142 kg h–1 versus GHGRP’s 360 kg h–1, while GHGSat reported 716 ± 355 kg h–1. These results have important implications, where terrain and road access permit, vehicle-based methods can yield emissions estimates comparable to aircraft- and satellite-based approaches. Additionally, the higher detection rate of vehicle-based surveys suggests superior performance in identifying methane anomalies. This study highlights the spatial and temporal variability of methane emissions from underground coal mines and emphasizes the importance of integrating multiple observational strategies to improve monitoring in underrepresented regions. It also provides a transferable framework for areas where limited data availability has hindered effective methane tracking and mitigation planning. 

Abstract The Last Glacial Maximum (19–23 thousand years ago) was characterized by low greenhouse gas concentrations and continental ice sheets that covered large parts of North America and Europe¹. Glacial climate was therefore very different, with colder global mean temperatures and an increased Equator-to-pole temperature gradient, probably resulting in stronger westerlies². However, the state of the deep North Atlantic Ocean under these glacial climate forcings remains uncertain^3–6, particularly owing to the rarity of deep-ocean temperature and salinity constraints. Here we show that the temperature of the glacial deep (>1.5 km) Northwest Atlantic was approximately 0–2 °C (only 1.8 ± 0.5 °C (2 s.e.) colder than today), and, after accounting for the whole-ocean change, seawater δ¹⁸O was 0.3 ± 0.1‰ (2 s.e.) higher and can be traced back to the surface subtropics via the subpolar Northeast Atlantic and Nordic Seas. Together, our hydrographic data reveal the thermal and isotopic structure of the deep Northwest Atlantic and suggest sustained production of relatively warm and probably salty North Atlantic Deep Water during the Last Glacial Maximum. Furthermore, our results provide updated constraints for benchmarking Earth system models used to project future climate change. 

Ocean acidification poses a threat to coral skeleton formation via reductions in the saturation state of aragonite (Ω_Ar) in seawater. Given that corals precipitate their skeletons from a calcifying fluid supplied by seawater, reductions in seawater Ω_Arshould, in theory, confound calcification. Here, we reconstruct up to 200 years of coral calcifying fluid Ω_Ar, using Raman spectroscopy techniques, at approximately monthly resolution in twoPoritessp. skeletal cores from the Coral Sea region to investigate (i) the regulation of coral calcifying fluid Ω_Arand (ii) the skeletal calcification response to industrial-era ocean acidification. Our results reveal a significant increase in calcifying fluid Ω_Ar, suggesting that some corals may adjust to the pace of acidification in the wild more effectively than suggested by short-term laboratory studies. 

An analysis of the language we use in scientific practice is critical to developing more rigorous and sound methodologies. This article argues that how certain methods of description are commonly employed in cognitive science risks obscuring important features of an agent’s cognition. We propose to make explicit a method of description whereby the concept of cognitive distinctions is the core principle. A model of referential communication is developed and analyzed as a platform to compare methods of description. We demonstrate that cognitive distinctions, realized in a graph theoretic formalism, better describe the behavior and perspective of a simple model agent than other, less systematic or natural language–dependent methods. We then consider how different descriptions relate to one another in the broader methodological framework of minimally cognitive behavior. Finally, we explore the consequences of, and challenges for, cognitive distinctions as a useful concept and method in the tool kit of cognitive scientists. 

Abstract Experimental studies have demonstrated that solid solutions of minerals from the alunite group, with chemical compositions intermediate between the Al and Fe end-members, can be readily synthesized in the laboratory. In contrast, up until about a dozen years ago, there were no confirmed reports of alunite group minerals with intermediate Al-Fe compositions in natural settings, leading some to suggest that minerals with such compositions might not exist in nature. In recent years, however, alunite group minerals with intermediate Al-Fe compositions have been documented in a few isolated locations, which were previously limited to basalt-hosted acid-sulfate fumarole deposits and acid mine drainage pit lakes. These occurrences contrast with nearly all other reports of minerals from this group, whose measured chemical compositions are very close to either the Al or Fe end-members. Here, we report jarosite-alunite solid solutions containing approximately equal amounts of Al and Fe, which are found in mineralized fractures of the Aztec Sandstone in southeast Nevada. Analysis of the minerals by X-ray diffraction, Raman spectroscopy, and visible-near infrared spectroscopy confirms that they are bona fide solid solutions and not intimate mixtures of end-member minerals. This study represents the first documented occurrence of alunite group solid solutions with intermediate Al-Fe compositions in sedimentary rocks. The results further demonstrate that alunite group minerals with a wide range of Al-Fe compositions occur naturally and can persist for millions of years or more in natural systems. 

Synapses of retinal rod photoreceptors involve deep invaginations occupied by second-order rod bipolar cell (RBP) and horizontal cell (HC) dendrites. Synaptic vesicles are released into this invagination at multiple sites beneath an elongated presynaptic ribbon. To study the impact of this architecture on glutamate diffusion and receptor activity, we reconstructed four rod terminals and their postsynaptic dendrites from serial electron micrographs of the mouse retina. We incorporated these structures into anatomically realistic Monte Carlo simulations of neurotransmitter diffusion and receptor activation. By comparing passive diffusion of glutamate in realistic structures with geometrically simplified models, we found that glutamate exits anatomically realistic synapses 10-fold more slowly than previously predicted. Constraining simulations with physiological data, we modeled activity of EAAT5 glutamate transporters in rods, AMPA receptors on HC dendrites, and metabotropic glutamate receptors (mGluR6) on RBP dendrites. Simulations suggested that ∼3,000 EAAT5 populate rod membranes. While uptake by surrounding glial Müller cells retrieves most glutamate released by rods, binding and uptake by EAAT5 influence RBP kinetics. Glutamate persistence allows mGluR6 on RBP dendrites to integrate the stream of vesicles released by rods in darkness. Glutamate’s tortuous diffusional path confers quantal variability, as release from nearby ribbon sites exerts larger effects on RBP and HC receptors than release from more distant sites. Temporal integration supports slower sustained release rates, but additional quantal variability can impede postsynaptic detection of changes in release produced by rod light responses. These results show an example of the profound impact that synaptic architecture can have on postsynaptic responses.