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This paper investigates quenching solutions of an one-dimensional, two-sided Riemann–Liouville fractional order convection–diffusion problem. Fractional order spatial derivatives are discretized using weighted averaging approximations in conjunction with standard and shifted Grünwald formulas. The advective term is handled utilizing a straightforward Euler formula, resulting in a semi-discretized system of nonlinear ordinary differential equations. The conservativeness of the proposed scheme is rigorously proved and validated through simulation experiments. The study is further advanced to a fully discretized, semi-adaptive finite difference method. Detailed analysis is implemented for the monotonicity, positivity and stability of the scheme. Investigations are carried out to assess the potential impacts of the fractional order on quenching location, quenching time, and critical length. The computational results are thoroughly discussed and analyzed, providing a more comprehensive understanding of the quenching phenomena modeled through two-sided fractional order convection-diffusion problems. 

Introduction to the project. 

ABSTRACT Recently, there has been a surge of international interest in extraterrestrial exploration targeting the Moon, Mars, the moons of Mars, and various asteroids. This contribution discusses how current state‐of‐the‐art Earth‐based testing for designing rovers and landers for these missions currently leads to overly optimistic conclusions about the behavior of these devices upon deployment on the targeted celestial bodies. The key misconception is that gravitational offset is necessary during theterramechanicstesting of rover and lander prototypes on Earth. The body of evidence supporting our argument is tied to a small number of studies conducted during parabolic flights and insights derived from newly revised scaling laws. We argue that what has prevented the community from fully diagnosing the problem at hand is the absence of effective physics‐based models capable of simulating terramechanics under low‐gravity conditions. We developed such a physics‐based simulator and utilized it to gauge the mobility of early prototypes of the Volatiles Investigating Polar Exploration Rover. This contribution discusses the results generated by this simulator, how they correlate with physical test results from the NASA‐Glenn SLOPE lab, and the fallacy of the gravitational offset in rover and lander testing. The simulator, which is open‐source and publicly available, also supports studies for in situ resource utilization activities, for example, digging, bulldozing, and berming, in low‐gravity environments. 

The realized niche of many sessile intertidal organisms is constrained by different stressors that set boundaries for their distribution based on tidal elevation. Higher tidal elevation increases desiccation risk but can provide a refuge from predation. Conversely, deeper water increases feeding time and growth but also increases vulnerability to benthic predators. Eastern oysters Crassostrea virginica harden their shells in response to predator cues, which reduces their mortality from predation. We performed a field study to investigate if this defense mechanism could be manipulated to expand their realized niche and increase space for oyster survival and growth. We raised oysters in the presence of predators (blue crabs Callinectes sapidus) or in nopredator controls, measured changes in shell morphology, and then monitored oyster survival at different tidal elevations across 7 locations with different predator and salinity regimes. Oyster survival was significantly higher at the highest tidal elevations tested. Exposure to predators before deployment also significantly increased shell hardness and survival, with intertidal oysters experiencing greater improvement in survival from cue exposure than subtidal oysters. Intertidal placement (>15% exposure time) had larger effects on survival than predator exposure, but predator exposure increased oyster survival at all tidal elevations, suggesting that predator induction could help oysters both deter predators and resist abiotic stressors like desiccation, and perhaps increase the spatial areas where oysters can be restored 

Abstract. Reducing methane emissions from the oil and gas (oil–gas) sector has been identified as a critically important global strategy for reducing near-term climate warming. Recent measurements, especially by satellite and aerial remote sensing, underscore the importance of targeting the small number of facilities emitting methane at high rates (i.e., “super-emitters”) for measurement and mitigation. However, the contributions from individual oil–gas facilities emitting at low emission rates that are often undetected are poorly understood, especially in the context of total national- and regional-level estimates. In this work, we compile empirical measurements gathered using methods with low limits of detection to develop facility-level estimates of total methane emissions from the continental United States (CONUS) midstream and upstream oil–gas sector for 2021. We find that of the total 14.6 (12.7–16.8) Tg yr−1 oil–gas methane emissions in the CONUS for the year 2021, 70 % (95 % confidence intervals: 61 %–81 %) originate from facilities emitting <100kgh-1 and 30 % (26 %–34 %) and ∼80 % (68 %–90 %) originate from facilities emitting <10 and <200kgh-1, respectively. While there is variability among the emission distribution curves for different oil–gas production basins, facilities with low emissions are consistently found to account for the majority of total basin emissions (i.e., range of 60 %–86 % of total basin emissions from facilities emitting <100kgh-1). We estimate that production well sites were responsible for 70 % of regional oil–gas methane emissions, from which we find that the well sites that accounted for only 10 % of national oil and gas production in 2021 disproportionately accounted for 67 %–90 % of the total well site emissions. Our results are also in broad agreement with data obtained from several independent aerial remote sensing campaigns (e.g., MethaneAIR, Bridger Gas Mapping LiDAR, AVIRIS-NG (Airborne Visible/Infrared Imaging System – Next Generation), and Global Airborne Observatory) across five to eight major oil–gas basins. Our findings highlight the importance of accounting for the significant contribution of small emission sources to total oil–gas methane emissions. While reducing emissions from high-emitting facilities is important, it is not sufficient for the overall mitigation of methane emissions from the oil and gas sector which according to this study is dominated by small emission sources across the US. Tracking changes in emissions over time and designing effective mitigation policies should consider the large contribution of small methane sources to total emissions. 

Carotenoid cleavage dioxygenases (CCDs) are non-heme FeII enzymes that catalyze the oxidative cleavage of alkene bonds in carotenoids, stilbenoids, and related compounds. How these enzymes control the reaction of O2 with their alkene substrates is unclear. Here, we apply spectroscopy in conjunction with X-ray crystallography to define the iron coordination geometry of a model CCD, CAO1, in its resting state and following substrate binding and coordination sphere substitutions. Resting CAO1 exhibits a five-coordinate (5C), square pyramidal FeII center that undergoes steric distortion towards a trigonal bipyramidal geometry in the presence of piceatannol. Titrations with the O2-analog, nitric oxide (NO), show a >100-fold increase in iron-NO affinity upon substrate binding, defining a crucial role for the substrate in activating the FeII site for O2 reactivity. The importance of the 5C FeII structure for reactivity was probed through mutagenesis of the second-sphere Thr151 residue of CAO1, which occludes ligand binding at the sixth coordination position. A T151G substitution resulted in the conversion of the iron center to a six-coordinate (6C) state and a 135-fold reduction in apparent catalytic efficiency towards piceatannol compared to the wild-type enzyme. Substrate complexation resulted in partial 6C to 5C conversion, indicating solvent dissociation from the iron center. Additional substitutions at this site demonstrated a general functional importance of the occluding residue within the CCD superfamily. Taken together, these data suggest an ordered mechanism of CCD catalysis occurring via substrate-promoted solvent replacement by O2. CCDs thus represent a new class of mononuclear non-heme FeII enzymes. 

One approach to improve long-term coral restoration success utilizes naturally stress-tolerant corals from the wild. While the focus has primarily been on thermal stress, low oxygen is a growing threat to coral reefs and restoration efforts should also consider hypoxia tolerance. Here we determine if Siderastrea siderea and Agaricia tenuifolia populations from a reef with a historical record of low oxygen exhibit evidence of local adaptation to hypoxic events, compared to populations from a reference reef. We employed a laboratory-based reciprocal transplant experiment mimicking a severe 14-night hypoxic event and monitored bleaching responses, photo-physiology, metabolic rates, and survival of all four populations during, and for two weeks following the event. In both species, we found the populations from the hypoxic reef either fully persisted or recovered within 3 days of the event. In contrast, the conspecific naïve populations from the well-oxygenated reference reef experienced bleaching and death. This showcases the vulnerability of naïve corals exposed to low oxygen but also suggests that corals from the hypoxic reef locally adapted to survive severe episodic hypoxia. Other reefs with past episodic low oxygen may also be home to corals with adaptation signatures to hypoxia and may be useful for restoration efforts. 

Feminist political ecologies of land have long traced how land dispossession impacts women and exacerbates gender inequalities. However, there remains limited work on land compensation in extractive economies. In this article, we take this up via a focus on oil development in Uganda. We examine how compensation is bound up with, and reinforces, power inequalities of gender, marital status, ethnicity, and class. In particular, we focus on women positioned as non-favored or ‘secondary’ wives, highlighting their particular vulnerabilities to dispossession during compensation and resettlement. Our research is based on interviews, participant observation, and focus groups with secondary wives conducted in 2015, 2018 and 2024 in Kabaale Parish in the Albertine Graben region of Western Uganda. We trace the legal and socio-cultural norms that enable women’s dispossession, as well as their resilience following land loss. We trace the ways that intimacies of family, marriage, and interpersonal relationships are tightly interwoven with state policy, land wealth, access to compensation, and control of resources. We show that the land dispossession of secondary wives is not only a fall-out of oil extraction, but also facilitates it, making the process more lucrative for companies, the Ugandan state and, to a lesser extent, for resettled husbands. Our work makes important contributions to feminist political ecologies of land, marriage, and oil and gas industrial development in Global South settings. Given the centrality of patriarchy to extractive theft, we assert that analyses of this industry must consider the intimate and intersectional politics of compensation. 

We define the equivariant degree and local degree of a proper G-equivariant map between smooth G-manifolds when G is a compact Lie group and prove a local to global result. We show the local degree can be used to compute the equivariant Euler characteristic of a smooth, compact G-manifold and the Euler number of a relatively oriented G-equivariant vector bundle when G is finite. As an application, we give an equivariantly enriched count of rational plane cubics through a G-invariant set of 8 general points in ℂℙ2, valued in the representation ring and Burnside ring of a finite group. When ℤ/2 acts by pointwise complex conjugation this recovers a signed count of real rational cubics.