S L Stephens results 369
· Newest (Page 1/15, per page 25)
Author: S L Stephens ×Clear All Filters
Search Results
Periodical cicada ( Magicicada spp.) ranges have continued to decline even as their habitat has rebounded from historic lows. This counterintuitive trajectory may be a consequence of Magicicada 's limited dispersal capabilities combined with their requirement that individual host trees survive across decades. Indeed, we find that the presence of Magicicada breeding populations is best predicted by tree cover in 1930, not by pr...
Amazon Dry Season Will Lengthen Under Future ClimateNARA Subscribed
The Amazon rainforest is a key component of the Earth system, regulating regional climate, sustaining high biodiversity and carbon stocks. However, it is threatened by climate and land‐use changes. In recent decades, the region has experienced intensified droughts and heatwaves, trends expected to worsen under future warming. In this study, we assess how the timing, length, and spatial distribution of the dry season across the...
Effect of six weeks ubiquinol supplementation on mitochondrial respiratory function and exercise capacity in healthy malesNARA Subscribed
Coenzyme Q10 (CoQ 10 ) is an integral component of the mitochondrial electron transfer system. Most studies have administered the oxidised form of CoQ 10 (ubiquinone) and observed no effects on mitochondrial respiratory function or endurance exercise performance. The reduced form of CoQ 10 , ubiquinol (UQH 2 ), has greater bioavailability than ubiquinone, but the effects of UQH 2 supplementation on mitochondrial respiratory fu...
Interpretable deep learning reveals spatiotemporal MRI features of brain aging that align with neurodegenerationNARA Subscribed
Cortical thinning and atrophy are hallmarks of brain aging that have been characterized using magnetic resonance imaging (MRI). Brain aging involves many neuroanatomic features whose effects on brain structure remain unexplored. To address this challenge, we trained interpretable deep neural networks (DNNs) to estimate brain age (BA) from T 1 -weighted ( T 1 w) MRI. By identifying MRI features unapparent to humans, DNNs can fi...
Assembling the Neotropical Tree Flora: Andean Uplift and the Historical Biogeography of the Brazil Nut Family (Lecythidaceae)NARA Subscribed
Aim The assembly of tropical tree floras is complex, involving many lineage‐specific histories; however, focusing on the biogeographic history of diverse clades can reveal general patterns. We investigated the historical biogeography of the ecologically important Brazil nut clade (Lecythidoideae) to: (1) expand prior phylogenies with greater sampling of the early branching Andean‐centered subclades; (2) infer the ages and disp...
SNAPSHOT USA 2024: Year 6 of the Coordinated National Camera Trap Survey of the United StatesNARA Subscribed
Motivation SNAPSHOT USA is an annual, multi‐contributor camera trap survey of mammals across the United States. The growing SNAPSHOT USA dataset is intended for tracking the spatial and temporal responses of mammal populations to changes in land use, land cover and climate. These data will be useful for exploring the drivers of spatial and temporal changes in relative abundance and distribution, as well as the impacts of speci...
Coexistence of Photosynthetic Marine Microorganisms, Viruses and Grazers: Towards Integration in Ocean Ecosystem ModelsNARA Subscribed
Photosynthetic microorganisms are responsible for primary production at the base of the marine food web and influence global biogeochemistry. Their growth is balanced by mortality processes, including zooplankton grazing and viral lysis. These predators coexist despite competing for the same microorganisms. Here, we develop a community model of photosynthetic microorganisms, grazers and viruses that incorporates elemental quot...
Exploring the potential of liver microphysiological systems of varied configurations to model cholestatic chemical effectsNARA Subscribed
Human in vitro liver tissue models have evolved to maintain hallmarks of hepatocellular function for extended periods with potential to model aspects of cholestasis for drug and chemical safety applications. Microphysiological systems (MPS) have been suggested as promising new approaches to model liver physiology and predict chemical-induced cholestasis in humans. This study comprehensively compared both basal function and tox...
Alzheimer’s disease (AD) disproportionately affects women and carriers of the apolipoprotein E ε4 allele (APOE4), yet little is known about how sex and APOE interact to influence white matter (WM) integrity during disease progression. We integrated diffusion MRI and matched blood transcriptomic data to investigate these interactions and their underlying biological mechanisms. WM microstructure was quantified using diffusion te...
Micro‐Refuges or Ecological Traps: Context‐Dependent Effects of Rock Pools on Intertidal Biodiversity Across LatitudesNARA Subscribed
Aim We investigated how local‐scale environmental heterogeneity influences biodiversity patterns across broad biogeographic gradients, using intertidal microhabitats as a model system within one of the most environmentally stressful ecosystems on Earth. Location Intertidal habitats at 26 locations (two rocky shore sites per location) across six continents, spanning 98° of latitude (38°S to 60°N). Time Period 2019–2022. Major T...
Marine megafauna species are affected by a wide range of anthropogenic threats. To evaluate the risk of such threats, species’ vulnerability to each threat must first be determined. We build on the existing threats classification scheme and ranking system of the International Union for Conservation of Nature (IUCN) Red List of Threatened Species by assessing the vulnerability of 256 marine megafauna species to 23 at‐sea threat...