67639 research outputs found
Sort by
Coral bleaching: the equatorial-refugia hypothesis
No full textThe rising threat of marine heatwaves has led to numerous predictions that coral reefs, especially those near the Equator, will be severely degraded by the end of the current century. Yet, environmental conditions near the Equator may regionally moderate coral bleaching by reducing thermal stress during marine heatwaves. We deployed a Bayesian spatio-temporal model over Earth to examine which environmental conditions may characterize marine-heatwave refugia for coral reefs by testing the relationship between the severity of coral bleaching and a suite of temperature, hydrodynamic, topographic, atmospheric, and biological variables. The model considered the severity of coral bleaching as the proportion of bleached hard corals during 30,266 coral-reef surveys conducted at 8,728 sites, at depths up to 20 meters, and located between 35 degrees north and south of the Equator across 81 countries, from 2002 to 2020. Except for the eastern Pacific Ocean, the severity of coral bleaching during marine heatwaves was lower on equatorial reefs than on higher-latitude reefs, suggesting that marine-heatwave refugia for corals have been concentrated in the equatorial Coral Triangle region. Indeed, equatorial reefs in the Coral Triangle were, on average, exposed to the weakest marine heatwaves, potentially because they were shielded from extreme isolation by frequent cloud coverage in the Intertropical Convergence Zone. Coral bleaching may also be moderated during marine heatwaves in refugia that experience high wave energy, high current velocity, high cloud frequency, or turbidity. Coral bleaching was also less severe on reefs that historically endured frequent heatwaves than on reefs that were naive to thermal stress. Based on modern and historical responses of coral reefs to acute thermal stress, we hypothesize that many equatorial reefs will continue to serve as marine-heatwave refugia for corals.We thank Sandra van Woesik and Chelsey Kratochwill for providing helpful editorial comments on the manuscript draft, Pallav Ray for an insightful discussion on cloud dynamics, and three anonymous reviewers for helpful comments and suggestions that improved the manuscript. We also thank Keith Van Graafeiland for deriving the tidal range data from the Finite Element Solution 2022 Tide product, which was (i) funded by the Centre National d’Etudes Spatiales, (ii) produced by the Laboratoire d'Etudes en Géophysique et Océanographie Spatiales, NOVELTIS, and Collecte Localisation Satellites, and (iii) made freely available by Archivage, Validation et Interprétation des données des Satellites Océanographiques. The National Science Foundation (NSF) Graduate Research Fellowship Program provided funding to RvW and ZF under award NSF DGE-2240237. NSF also provided funding to RvW under award NSF OCE-2048319. This is contribution number 260 from the Institute for Global Ecology at the Florida Institute of Technology
The emerging contribution of Tigris Euphrates basin dust emissions to extreme dust activity over the Arabian Peninsula.
No full textThe Arabian Peninsula (AP) is an epicenter of global dust activity, shaped by both local emissions and long-range transport. Recent observational studies suggest that the Tigris-Euphrates river basin (TE) is the dominant contributor to the intense dust periods over the AP. This study, for the first time, quantifies the influence of TE during these periods using a regionally tuned Weather Research and Forecasting model coupled with chemistry (WRF-Chem). Two simulations were conducted with WRF-Chem for three extreme dust seasons (March-August; 2009, 2011, and 2012): one with dust emissions from all sources, including TE, and the other with TE emissions excluded. Results show that excluding TE emissions significantly reduces mean atmospheric dust loading and decreases dust concentrations across atmospheric layers over the AP. Reduced dust concentrations enhance surface shortwave radiation, increasing solar energy potential and improving regional particulate air quality. This also contributes to cooler nighttime temperatures by limiting trapping of longwave radiation.Critically, our findings indicate that the dust transport from TE controls the intensity and frequency of dust events in the AP during the study period. Suppressing TE dust emissions leads to a substantial reduction over 50% in the occurrence of extreme dust events over the AP. At the same time, it increases the prevalence of moderate and heavy dust events across most of the region. The Kingdom of Saudi Arabia (KSA) is pursuing ambitious strategies to mitigate dust extremes. Effective action depends on identifying dominant sources and their contributions. This study quantifies the impact of the remote TE source on KSA dust extremes, offering a strong basis for targeted control measures.This research was supported by the Climate Change Centre at KAUST, an initiative of the National Center for Meteorology (NCM), Kingdom of Saudi Arabia (Ref No: RGC/03/4829–01-01)
Unprecedented 2020 coral bleaching reveals unexpected taxa-specific responses in the central Red Sea.
No full textSea surface temperature of the Red Sea has increased by up to 0.45 °C per decade over the last 30 years, and coral bleaching events are becoming more frequent. A reef bleaching event was observed in October 2020, whereby some parts of the Red Sea experienced more than 12 °C-weeks. The study sites spanned nearly three degrees of latitude along the central Saudi Arabian Red Sea and were surveyed via structure-from-motion photogrammetry in October 2020 during the bleaching event and again in October 2022 to track the fate of the coral colonies. The in situ temperatures in 2020 ranged from 31.9 °C to 32.7 °C, and overall, 65% of the colonies exhibited some bleaching. Nearly half of the colonies exhibited partial or complete mortality in 2022, although 18% exhibited complete mortality. Approximately 27% of the colonies presented no visible change in coloration over the study period, whereas 21% presented recovery over the two years. Porites, Montipora, Pocillopora, and Stylophora were classified as winners, whereas Acropora, Goniastrea, Xeniidae, and Sclerophytum were classified as losers. At the time of this study, this research was the first to assess the longest-term changes in coral colonies following a major reef bleaching event in the central Saudi Arabian Red Sea. The results suggest that the 2020 bleaching event may be the most severe event on record for the region at the time of the study, and our data underscore the need for enhanced monitoring of corals and environmental data to better understand coral reef ecosystem resilience in a historically data scarce region.We would like to thank Dream Divers for their support at sea and KAUST Coastal and Marine core labs for providing technical support onboard. We would like to thank Dr. Tullia Terraneo for planning the 2020 expedition and Dr. Fabio Marchese for planning the 2022 expedition. We further appreciate Dr. Ivor Williams, Rhonda Suka, and Dr. Luis Silva for their collaboration in developing a standardized SfM field methodology and Brian Nieuwenhuis for statistical analysis support
In Situ High Selectivity Contact-Electroreduction of CO2 to Methanol Using an Imine-Mediated Metal-Free Vitrimer Catalyst.
No full textMetal catalysts for CO2 reduction reaction (CO2RR) face challenges such as high cost, limited durability and environmental impact. Although various diverse and functional metal-free catalysts have been developed, they often suffer from slow kinetics, low selectivity, and non-recyclability, significantly limiting their practical applications. In this study, we introduce a recyclable non-metallic polymer material (vitrimer) for a new platform in contact-electro-catalysis. This approach harnesses the contact charges generated between water droplets and vitrimer to drive CO2RR, achieving methanol selectivity exceeding 90%. The imine groups within the vitrimer play a dual role, facilitating CO2 adsorption and enriching friction-generated electrons, thereby mediating efficient electron transfer between the imine groups and CO2 to promote CO2RR. After 84 h, the system achieved a methanol production rate of 13 nmol·h-1, demonstrating the excellent stability of the method. Moreover, the vitrimer retains its high-performance electrocatalytic activity even after recycling. Mechanistic studies reveal that, compared to traditional metal catalysts, the N-O bond in the imine, which adsorbs the key intermediate *OCH3, breaks more readily to produce methanol, resulting in enhanced product selectivity and yield. This efficient and environmentally friendly contact-electroreduction strategy for CO2 offers a promising pathway toward a circular carbon economy by leveraging natural water droplet-based contact-electrochemistry
Optical identification and anti-counterfeiting based on plasmonic core–shell nanoparticles with Fano resonance
No full textFano resonance with an asymmetric and ultrasharp resonant line shape has been extensively studied in various light scattering scenes, unlocking several applications for sensing, information processing, and optical identification. Fano resonance appearing in multilayered nanoparticles (NPs) is particularly intriguing as its sharp and comb-like resonant line shape may enable optical identification at the nanoscale. We herein propose the concept of the optical physical unclonable function (PUF) based on the scattering responses of core–shell (plasmonic-dielectric) NPs. Specifically, the sharp, asymmetric spectral responses near the Fano resonance frequency, which are highly sensitive to perturbations (e.g., nanomanufacturing imperfections), can be exploited as a unique electromagnetic fingerprint for PUF-based identification and anti-counterfeiting applications. Here, we theoretically and statistically demonstrate that scattering from Fano-resonant multilayered NPs can be regarded as a perfect entropy source for the generation of PUF encryption keys, with outstanding performance in terms of uniqueness, randomness, encoding capacity, and NIST randomness test results. The proposed optical PUF opens pathways to implement nano-tags for optical identification, authentication, and anti-counterfeiting applications
CRISPR Diagnostics as Next-Generation Tools for Rapid and Accessible Molecular Testing: Innovations and Applications
No full textRapid and accurate diagnostic testing is critical for patient care, outbreak containment, and optimized allocation of healthcare resources. Standard nucleic acid–based testing, such as PCR, immunoassays, and culture techniques, is subject to considerable trade-offs, leaving room for compromises between speed, precision, and availability.
CRISPR-based testing using Cas12 and Cas13 effectors provides for programmable and rapid alternatives using collateral cleavage activity with fluorescent reporters for sensitive identifications of DNA or RNA targets. While advantageous, platforms using CRISPR are subject to disadvantages such as pre-amplification dependency (LAMP, RPA, PCR), sequence constraints (PAM/PFS requirements), collateral cleavage activity, sample-preparation challenges, and commercialization and regulatory challenges.
Recent innovations—specifically one-pot closed-tube assays, thermostable and genetically engineered nucleases, photoswitchable guides, transduction systems without amplification, microfluidic and electrochemical readouts, and multiplexed platforms such as CARMEN—remediate numerous of these challenges. CRISPR testing instruments have been applied broadly as tools for the identifications of infectious diseases, point-of-care testing, oncological testing, environmental and food safety monitoring, and large-scale pathogen surveillance. Overall, such innovations showcase CRISPR-based testing instruments as versatile, rapid, and field-deployable tools capable of disrupting
conventional diagnostic trade-offs and providing a means towards timely, accurate, and accessible testing across a variety of clinical and public-health applications.We acknowledge KAUST Academy and Prof. Magdy Mahfouz for supporting this work
FCPCA: Fuzzy clustering of high-dimensional time series based on common principal component analysis
No full textClustering multivariate time series data is a crucial task in many domains, as it enables the identification of meaningful patterns and groups in time-evolving data. Traditional approaches, such as crisp clustering, rely on the assumption that clusters are sufficiently separated with little overlap. However, real-world data often defy this assumption, showing overlapping distributions or overlapping clouds of points and blurred boundaries between clusters. Fuzzy clustering offers a compelling alternative by allowing partial membership in multiple clusters, making it well-suited for these ambiguous scenarios. Despite its advantages, current fuzzy clustering methods primarily focus on univariate time series, and for multivariate cases, even datasets of moderate dimensionality become computationally prohibitive. This challenge is further exacerbated when dealing with time series of varying lengths, leaving a clear gap in addressing the complexities of modern datasets. This work introduces a novel fuzzy clustering approach based on common principal component analysis to address the aforementioned shortcomings. Our method has the advantage of efficiently handling high-dimensional multivariate time series by reducing dimensionality while preserving critical temporal features. Extensive numerical results show that our proposed clustering method outperforms several existing approaches in the literature. An interesting application involving brain signals from different drivers recorded from a simulated driving experiment illustrates the potential of the approach.We sincerely thank the three referees for their careful review and valuable comments, which have greatly helped us improve the quality of our manuscript. This research was supported by King Abdullah University of Science and Technology (KAUST)
Non-Euclidean Broximal Point Method: A Blueprint for Geometry-Aware Optimization
No full textThe recently proposed Broximal Point Method (BPM) [Gruntkowska et al., 2025] offers an idealized optimization framework based on iteratively minimizing the objective function over norm balls centered at the current iterate. It enjoys striking global convergence guarantees, converging linearly and in a finite number of steps for proper, closed and convex functions. However, its theoretical analysis has so far been confined to the Euclidean geometry. At the same time, emerging trends in deep learning optimization, exemplified by algorithms such as Muon [Jordan et al., 2024] and Scion [Pethick et al., 2025], demonstrate the practical advantages of minimizing over balls defined via non-Euclidean norms which better align with the underlying geometry of the associated loss landscapes. In this note, we ask whether the convergence theory of BPM can be extended to this more general, non-Euclidean setting. We give a positive answer, showing that most of the elegant guarantees of the original method carry over to arbitrary norm geometries. Along the way, we clarify which properties are preserved and which necessarily break down when leaving the Euclidean realm. Our analysis positions Non-Euclidean BPM as a conceptual blueprint for understanding a broad class of geometry-aware optimization algorithms, shedding light on the principles behind their practical effectiveness.The research reported in this publication was supported by funding from King Abdullah University of Science and Technology (KAUST): i) KAUST Baseline Research Scheme, ii) CRG Grant ORFS-CRG12-2024-6460, and iii) Center of Excellence for Generative AI, under award number 5940
CCDC 2347189: Experimental Crystal Structure Determination : tetrakis(N,N-diethyl-N-methylethanaminium) heptakis(thiocyanato)-erbium(iii)
No full textAn entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures
Dynamic construction of a durable epitaxial catalytic layer for industrial alkaline water splitting
No full textOptimizing the catalyst-electrolyte interface structure is crucial for enhancing the performance of electrochemical alkaline hydrogen evolution reaction. Traditional approaches typically focus on regulating the thermodynamic barriers of adsorption and desorption for reactants, intermediates, and ions at active sites on the solid electrode surface. However, the structure of the electrical double layer influences the concentration of intermediates, adsorption energy, and surface reaction kinetics. Here, we dynamically construct a dense epitaxial hydroxide layer on nickel molybdate, forming an effective protective barrier to prevent molybdenum leaching and enhance material stability. This optimization enhances local electric field increasing the concentration of hydrated potassium ions within the outer Helmholtz plane. As a result, the interfacial hydrogen-bond network improves, water availability on the catalyst surface increases, and reaction kinetics accelerate. The optimized material operates stably for 1400 h at a current density of 0.45 A cm-2 in an industrial alkaline electrolyzer. Our dual-optimization strategy of dynamically constructing an epitaxial catalytic layer offers valuable insights for developing stable, high-current-density electrocatalytic materials.This work received financial support from King Abdullah University of Science and Technology (KAUST) and Center of Excellence for Renewable Energy and Storage Technologies under award number 5937, National Natural Science Foundation of China (52202366), Natural Science Foundation of Shandong Province (2025HWYQ-050, ZR2021QE011, ZR2021JQ15), Taishan Scholar Project of Shandong Province (tstp20240515, tsqn202312217), and Innovative Team Project of Jinan (2021GXRC019). For computer time, this research used Shaheen III and Ibex managed by the KAUST Supercomputing Core Laboratory under project K10175