bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Atlantic Meridional Overturning Circulation at 35°N From Deep Moorings, Floats, and Satellite Altimeter
Authors: Le Bras Isabela Alexander‐Astiz , Willis Josh , Fenty Ian 
Published: May 2023

AbstractFrom 2004 to 2014, the Line W moorings measured a 0.7 Sv yr−1 slowing of the deep western boundary current (DWBC) offshore of Cape Cod. Here, we combine these deep mooring observations with float and satellite altimeter data and find that this DWBC change corresponded to a slowing of the cross‐basin Atlantic Meridional Overturning Circulation (AMOC) of about 0.3 Sv yr−1. Our AMOC transport time series corresponds well with the Estimating the Circulation and Climate of the Ocean state estimate, particularly when the Line W mooring data influences our volume closure. We compare our 35°N time series with a similar time series at 41°N as well as the 26°N RAPID AMOC, and find AMOC declines across datasets from 2004 to 2014. However, when we extend our analysis to 2004–2019, there are no significant trends at any latitude. These observations suggest that AMOC decadal variability is meridionally coherent from 26°N to 41°N and that the DWBC may reflect this variability.
Deep Long‐Period Earthquakes at Akutan Volcano From 2005 to 2017 Better Track Magma Influxes Compared to Volcano‐Tectonic Earthquakes
Authors: Song Zilin , Tan Yen Joe , Roman Diana C. 
Published: May 2023

AbstractBoth volcano‐tectonic (VTs) and deep long‐period earthquakes (DLPs) have been documented at Akutan Volcano, Alaska and may reflect different active processes helpful for eruption forecasting. In this study, we perform high‐resolution earthquake detection, classification, and relocation using seismic data from 2005 to 2017 to investigate their relationship with underlying magmatic processes. We find that the 2,787 VTs and 787 DLPs are concentrated above and below the inferred magma reservoir respectively. They both are clustered as swarms and occur preferentially during inflation episodes with no spatial migrations. However, moment release rates of DLP swarms show a stronger correlation with inflation and their low‐frequency content is likely a source instead of a path effect. Therefore, we infer that DLPs are directly related to unsteady magma movement through a complex pathway. In comparison, repeating events are observed in VTs. Thus, we conclude that they represent fault rupture triggered by magma/fluid movement or larger earthquakes.
Upward Lightning at the Gaisberg Tower: The Larger‐Scale Meteorological Influence on the Triggering Mode and Flash Type
Authors: Stucke Isabell , Morgenstern Deborah , Diendorfer Gerhard , Mayr Georg J. , Pichler Hannes , Schulz Wolfgang , Simon Thorsten , Zeileis Achim 
Published: May 2023

AbstractUpward lightning is rarer than downward lightning and requires tall (100+ m) structures to initiate. It may be either self‐initiated or triggered by other lightning discharges. While conventional lightning location systems (LLSs) detect most of the upward lightning flashes superimposed by pulses or return strokes, they miss a specific flash type that consists only of a continuous current. Globally, only few specially instrumented towers can record this flash type. The proliferation of wind turbines in combination with damages from upward lightning necessitates an improved understanding under which conditions self‐initiated upward lightning and the continuous‐current‐only subtype occur. This study uses a random forest machine learning model to find the larger‐scale meteorological conditions favoring the occurrence of the different phenomena. It combines ground truth lightning current measurements at the specially instrumented tower at Gaisberg mountain in Austria with variables from larger‐scale meteorological reanalysis data (ERA5). These variables reliably explain whether upward lightning is self‐initiated or triggered by other lightning discharges. The most important variable is the height of the −10°C isotherm above the tall structure: the closer it is, the higher is the probability of self‐initiated upward lightning. For the different flash types, this study finds a relationship to the larger‐scale electrification conditions and the LLS‐detected lightning situation in the vicinity. Lower amounts of supercooled liquid water, solid, and liquid differently sized particles and no LLS‐detected lightning events nearby favor the continuous‐current‐only subtype compared to the other subtypes, which preferentially occur with LLS‐detected lightning events within 3 km from the Gaisberg Tower.
Deep Learning for Downscaling Tropical Cyclone Rainfall to Hazard‐Relevant Spatial Scales
Authors: Vosper Emily , Watson Peter , Harris Lucy , McRae Andrew , Santos‐Rodriguez Raul , Aitchison Laurence , Mitchell Dann 
Published: May 2023

AbstractFlooding, driven in part by intense rainfall, is the leading cause of mortality and damages from the most intense tropical cyclones (TCs). With rainfall from TCs set to increase under anthropogenic climate change, it is critical to accurately estimate extreme rainfall to better support short‐term and long‐term resilience efforts. While high‐resolution climate models capture TC statistics better than low‐resolution models, they are computationally expensive. This leads to a trade‐off between capturing TC features accurately, and generating large enough simulation data sets to sufficiently sample high‐impact, low‐probability events. Downscaling can assist by predicting high‐resolution features from relatively cheap, low‐resolution models. Here, we develop and evaluate a set of three deep learning models for downscaling TC rainfall to hazard‐relevant spatial scales. We use rainfall from the Multi‐Source Weighted‐Ensemble Precipitation observational product at a coarsened resolution of ∼100 km, and apply our downscaling model to reproduce the original resolution of ∼10 km. We find that the Wasserstein Generative Adversarial Network is able to capture realistic spatial structures and power spectra and performs the best overall, with mean biases within 5% of observations. We also show that the model can perform well at extrapolating to the most extreme storms, which were not used in training.
Temporal Evolution of Dune Number Density in a Barchan Dune Field
Authors: Xiao Xiang , Liu Hongyou , Zheng Xiaojing 
Published: May 2023

AbstractThe present work examines the temporal evolution of dune number density in desert barchan dune fields and the effects of wind velocity, particle diameter and sand supply thickness using the Comprehensive Scale‐Coupled Model of dune field considering turbulence. Results show that the dune number density exhibits a temporal evolution trend of “increase—decrease—tend to be stable,” which is similar to the “overshoot” phenomenon of the per unit width sand transport rate evolving with time. The larger the wind velocity and the smaller the particle diameter are, the enhanced surface sand transport by wind causes the dune number density peak to be larger and appear earlier, but the more active dune interactions result in a higher decay rate during the decline stage. In addition, a small sand supply thickness slows sand accumulation and thus delays the initial development of barchans. With an increase in the sand supply thickness, more small‐scale barchans are formed earlier in dune fields due to gradually sufficient sand amounts, which promotes dune interactions and thus accelerates the decay of dune number density. Nevertheless, as the sand supply thickness continuously increases, the barchans link together to form dune chains, resulting in a slowed migration velocity and a reduced spatial density of interactions. The present work makes up for the lack of understanding of the initial evolution stage of barchan dune fields and the dune interactions in existing studies, and thus may be helpful for gaining insight into the dynamic evolution process of aeolian dune systems.
Methane Emissions in Seagrass Meadows as a Small Offset to Carbon Sequestration
Authors: Yau Yvonne Y. Y. , Reithmaier Gloria , Majtényi‐Hill Claudia , Serrano Oscar , Piñeiro‐Juncal Nerea , Dahl Martin , Mateo Miguel Angel , Bonaglia Stefano , Santos Isaac R. 
Published: May 2023

AbstractSeagrass meadows are effective carbon sinks due to high primary production and sequestration in sediments. However, methane (CH4) emissions can partially counteract their carbon sink capacity. Here, we measured diffusive sediment‐water and sea‐air CO2 and CH4 fluxes in a coastal embayment dominated by Posidonia oceanica in the Mediterranean Sea. High‐resolution timeseries observations revealed large spatial and temporal variability in CH4 concentrations (2–36 nM). Lower sea‐air CH4 emissions were observed in an area with dense seagrass meadows compared to patchy seagrass. A 6%−40% decrease of CH4 concentration in the surface water around noon indicates that photosynthesis likely limits CH4 fluxes. Sediments were the major CH4 source as implied from radon (a natural porewater tracer) observations and evidence for methanogenesis in deeper sediments. CH4 sediment‐water fluxes (0.1 ± 0.1–0.4 ± 0.1 μmol m−2 d−1) were higher than average sea‐air CH4 emissions (0.12 ± 0.10 μmol m−2 d−1), suggesting that dilution and CH4 oxidation in the water column could reduce net CH4 fluxes into the atmosphere. Overall, relatively low sea‐air CH4 fluxes likely represent the net emissions from subtidal seagrass habitat not influenced by allochthonous CH4 sources. The local CH4 emissions in P. oceanica can offset less than 1% of the carbon burial in sediments (142 ± 69 g CO2eq m−2 yr−1). Combining our results with earlier observations in other seagrass meadows worldwide reveals that global CH4 emissions only offset a small fraction (<2%) of carbon sequestration in sediments from seagrass meadows.
Constraints on Bend‐Faulting and Mantle Hydration at the Marianas Trench From Seismic Anisotropy
Authors: Mark Hannah F. , Lizarralde Daniel , Wiens Douglas A. 
Published: May 2023

AbstractSubduction zones are a key link between the surface water cycle and the solid Earth, as the incoming plate carries pore water and hydrous minerals into the subsurface. However, water fluxes from surface to subsurface reservoirs over geologic time are highly uncertain because the volume of water carried in hydrous minerals in the slab mantle is poorly constrained. Estimates of slab mantle hydration based on seismic tomography assume bulk serpentinization, representing an upper bound on water volume. We measure azimuthal seismic anisotropy near the Marianas Trench, use spatial variations in anisotropy to constrain the extent and geometry of bend‐related faulting, and place a lower bound on slab mantle water content for the case where serpentinization is confined within fault zones. The seismic observations can be explained by a minimum of ∼0.85 wt% water in the slab mantle, compared to the upper bound of ∼2 wt% obtained from tomography.
Asymmetry in the Seasonal Cycle of Zonal‐Mean Surface Air Temperature
Authors: Roach Lettie A. , Eisenman Ian , Wagner Till J. W. , Donohoe Aaron 
Published: May 2023

AbstractAt most latitudes, the seasonal cycle of zonal‐mean surface air temperature is notably asymmetric: the length of the warming season is not equal to the length of the cooling season. The asymmetry varies spatially, with the cooling season being ∼40 days shorter than the warming season in the subtropics and the warming season being ∼100 days shorter than the cooling season at the poles. Furthermore, the asymmetry differs between the Northern Hemisphere and the Southern Hemisphere. Here, we show that these observed features are broadly captured in a simple model for the evolution of temperature forced by realistic insolation. The model suggests that Earth's orbital eccentricity largely determines the hemispheric contrast, and obliquity broadly dictates the meridional structure. Clouds, atmospheric heat flux convergence, and time‐invariant effective surface heat capacity have minimal impacts on seasonal asymmetry. This simple, first‐order picture has been absent from previous discussions of the surface temperature seasonal cycle.
Magnetic Resonance Imaging of Multi‐Phase Lava Flow Analogs: Velocity and Rheology
Authors: Birnbaum Janine , Zia Wasif , Bordbar Alireza , Lee Ray F. , Boyce Christopher M. , Lev Einat 
Published: May 2023

AbstractThe rheology of lavas and magmas exerts a strong control on the dynamics and hazards posed by volcanic eruptions. Magmas and lavas are complex mixtures of silicate melt, suspended crystals, and gas bubbles. To improve the understanding of the dynamics and effective rheology of magmas and lavas, we performed dam‐break flow experiments using suspensions of silicone oil, sesame seeds, and N2O bubbles. Experiments were run inside a magnetic resonance imaging (MRI) scanner to provide imaging of the flow interior. We varied the volume fraction of sesame seeds between 0 and 0.48, and of bubbles between 0 and 0.21. MRI phase‐contrast velocimetry was used to measure liquid velocity. We fit an effective viscosity to the velocity data by approximating the stress using lubrication theory and the imaged shape of the free surface. In experiments with both particles and bubbles (three‐phase suspensions), we observed shear banding in which particle‐poor regions deform with a lower effective viscosity and dominate flow propagation speed. Our observations demonstrate the importance of considering variations in phase distributions within magmatic fluids and their implications on the dynamics of volcanic eruptions.
Obesity impairs cardiolipin-dependent mitophagy and therapeutic intercellular mitochondrial transfer ability of mesenchymal stem cells
Authors: Sagar Shakti , Faizan Md Imam , Chaudhary Nisha , Singh Vandana , Singh Praveen , Gheware Atish , Sharma Khushboo , Azmi Iqbal , Singh Vijay Pal , Kharya Gaurav , Mabalirajan Ulaganathan , Agrawal Anurag , Ahmad Tanveer , Sinha Roy Soumya 
Published: May 2023

AbstractMesenchymal stem cell (MSC) transplantation alleviates metabolic defects in diseased recipient cells by intercellular mitochondrial transport (IMT). However, the effect of host metabolic conditions on IMT and thereby on the therapeutic efficacy of MSCs has largely remained unexplored. Here we found impaired mitophagy, and reduced IMT in MSCs derived from high-fat diet (HFD)-induced obese mouse (MSC-Ob). MSC-Ob failed to sequester their damaged mitochondria into LC3-dependent autophagosomes due to decrease in mitochondrial cardiolipin content, which we propose as a putative mitophagy receptor for LC3 in MSCs. Functionally, MSC-Ob exhibited diminished potential to rescue mitochondrial dysfunction and cell death in stress-induced airway epithelial cells. Pharmacological modulation of MSCs enhanced cardiolipin-dependent mitophagy and restored their IMT ability to airway epithelial cells. Therapeutically, these modulated MSCs attenuated features of allergic airway inflammation (AAI) in two independent mouse models by restoring healthy IMT. However, unmodulated MSC-Ob failed to do so. Notably, in human (h)MSCs, induced metabolic stress associated impaired cardiolipin-dependent mitophagy was restored upon pharmacological modulation. In summary, we have provided the first comprehensive molecular understanding of impaired mitophagy in obese-derived MSCs and highlight the importance of pharmacological modulation of these cells for therapeutic intervention.
Pathological convergence of APP and SNCA deficiency in hippocampal degeneration of young rats
Authors: Wang Yajie , Miao Zhikang , Xu Chang , Cai Ying , Yang Yuting , Hu Yue , Zhao Mengna , Shao Yue , Li Zhiqiang , Chen Jincao , Chen Shi , Wang Lianrong 
Published: May 2023

AbstractThe common pathogenesis of Alzheimer’s disease (AD) and Parkinson’s disease (PD) has been supported by biochemical, genetic and molecular evidence. Mitochondrial dysfunction is considered to be the common pathology in early AD and PD. The physiological regulation of APP and α-synuclein on mitochondria remains unclear, let alone whether they share common regulatory mechanisms affecting the development of neurodegenerative diseases. By studying gene knockout rats, the commonality of physiological APP and α-synuclein in maintaining mitochondrial function through calcium homeostasis regulation was revealed, which was critical in inhibiting hippocampal degeneration in young rats. APP and α-synuclein both control hippocampal mitochondrial calcium intake and outflow. In the mitochondrial calcium influx regulation, APP and α-synuclein are located on the mitochondrial-associated endoplasmic reticulum membrane (MAM) and converge to regulate the IP3R1-Grp75-VDAC2 axis. Mitochondrial calcium outflow is redundantly promoted by both α-synuclein and APP. Loss of APP or SNCA leads to mitochondrial calcium overload, thus enhancing aerobic respiration and ER stress, and ultimately causing excessive apoptosis in the hippocampus and spatial memory impairment in young rats. Based on this study, we believe that the physiological function impairment of APP and SNCA is the early core pathology to induce mitochondrial dysfunction at the early stage of AD and PD, while the IP3R1-Grp75-VDAC2 axis might be the common drug target of these two diseases.
Cytoprotective autophagy as a pro-survival strategy in ART-resistant malaria parasites
Authors: Kannan Deepika , Joshi Nishant , Gupta Sonal , Pati Soumya , Bhattacharjee Souvik , Langsley Gordon , Singh Shailja 
Published: May 2023

AbstractDespite several initiatives to subside the global malaria burden, the spread of artemisinin-resistant parasites poses a big threat to malaria elimination. Mutations in PfKelch13 are predictive of ART resistance, whose underpinning molecular mechanism remains obscure. Recently, endocytosis and stress response pathways such as the ubiquitin-proteasome machinery have been linked to artemisinin resistance. With Plasmodium, however, ambiguity persists regarding a role in ART resistance for another cellular stress defence mechanism called autophagy. Therefore, we investigated whether, in the absence of ART treatment, basal autophagy is augmented in PfK13-R539T mutant ART-resistant parasites and analyzed whether PfK13-R539T endowed mutant parasites with an ability to utilize autophagy as a pro-survival strategy. We report that in the absence of any ART treatment, PfK13-R539T mutant parasites exhibit increased basal autophagy compared to PfK13-WT parasites and respond aggressively through changes in autophagic flux. A clear cytoprotective role of autophagy in parasite resistance mechanism is evident by the observation that a suppression of PI3-Kinase (PI3K) activity (a master autophagy regulator) rendered difficulty in the survival of PfK13-R539T ART-resistant parasites. In conclusion, we now show that higher PI3P levels reported for mutant PfKelch13 backgrounds led to increased basal autophagy that acts as a pro-survival response to ART treatment. Our results highlight PfPI3K as a druggable target with the potential to re-sensitize ART-resistant parasites and identify autophagy as a pro-survival function that modulates ART-resistant parasite growth.
Circ_0020256 induces fibroblast activation to drive cholangiocarcinoma development via recruitment of EIF4A3 protein to stabilize KLF4 mRNA
Authors: Li Zongyan , Chen Zuxiao , Li Shiying , Qian Xiangjun , Zhang Lei , Long Guojie , Xie Jiancong , Huang Xiaoming , Zheng Zheyu , Pan Weidong , Li Haiyan , Zhang Dawei 
Published: May 2023

AbstractCancer-associated fibroblasts (CAFs) are a kind of stromal cells in the cholangiocarcinoma (CCA) microenvironment, playing crucial roles in cancer development. However, the potential mechanisms of the interaction between CCA cells and CAFs remain obscure. This work investigated the role of circ_0020256 in CAFs activation. We proved circ_0020256 was up-regulated in CCA. High circ_0020256 expression facilitated TGF-β1 secretion from CCA cells, which activated CAFs via the phosphorylation of Smad2/3. Mechanistically, circ_0020256 recruited EIF4A3 protein to stabilize KLF4 mRNA and upregulate its expression, then KLF4 bound to TGF-β1 promoter and induced its transcription in CCA cells. KLF4 overexpression abrogated the inhibition of circ_0020256 silencing in TGF-β1/Smad2/3-induced CAFs activation. Furthermore, CCA cell growth, migration, and epithelial-mesenchymal transition were favored by CAFs-secreted IL-6 via autophagy inhibition. We also found circ_0020256 accelerated CCA tumor growth in vivo. In conclusion, circ_0020256 promoted fibroblast activation to facilitate CCA progression via EIF4A3/KLF4 pathway, providing a potential intervention for CCA progression.
Regorafenib inhibits EphA2 phosphorylation and leads to liver damage via the ERK/MDM2/p53 axis
Authors: Yan Hao , Wu Wentong , Hu Yuhuai , Li Jinjin , Xu Jiangxin , Chen Xueqin , Xu Zhifei , Yang Xiaochun , Yang Bo , He Qiaojun , Luo Peihua 
Published: May 2023

AbstractThe hepatotoxicity of regorafenib is one of the most noteworthy concerns for patients, however the mechanism is poorly understood. Hence, there is a lack of effective intervention strategies. Here, by comparing the target with sorafenib, we show that regorafenib-induced liver injury is mainly due to its nontherapeutic target Eph receptor A2 (EphA2). EphA2 deficiency attenuated liver damage and cell apoptosis under regorafenib treatment in male mice. Mechanistically, regorafenib inhibits EphA2 Ser897 phosphorylation and reduces ubiquitination of p53 by altering the intracellular localization of mouse double minute 2 (MDM2) by affecting the extracellular signal-regulated kinase (ERK)/MDM2 axis. Meanwhile, we found that schisandrin C, which can upregulate the phosphorylation of EphA2 at Ser897 also has protective effect against the toxicity in vivo. Collectively, our findings identify the inhibition of EphA2 Ser897 phosphorylation as a key cause of regorafenib-induced hepatotoxicity, and chemical activation of EphA2 Ser897 represents a potential therapeutic strategy to prevent regorafenib-induced hepatotoxicity.
Endothelial cell-derived stem cell factor promotes lipid accumulation through c-Kit-mediated increase of lipogenic enzymes in brown adipocytes
Authors: Lee Hyuek Jong , Lee Jueun , Yang Myung Jin , Kim Young-Chan , Hong Seon Pyo , Kim Jung Mo , Hwang Geum-Sook , Koh Gou Young 
Published: May 2023

AbstractActive thermogenesis in the brown adipose tissue (BAT) facilitating the utilization of lipids and glucose is critical for maintaining body temperature and reducing metabolic diseases, whereas inactive BAT accumulates lipids in brown adipocytes (BAs), leading to BAT whitening. Although cellular crosstalk between endothelial cells (ECs) and adipocytes is essential for the transport and utilization of fatty acid in BAs, the angiocrine roles of ECs mediating this crosstalk remain poorly understood. Using single-nucleus RNA sequencing and knock-out male mice, we demonstrate that stem cell factor (SCF) derived from ECs upregulates gene expressions and protein levels of the enzymes for de novo lipogenesis, and promotes lipid accumulation by activating c-Kit in BAs. In the early phase of lipid accumulation induced by denervation or thermoneutrality, transiently expressed c-Kit on BAs increases the protein levels of the lipogenic enzymes via PI3K and AKT signaling. EC-specific SCF deletion and BA-specific c-Kit deletion attenuate the induction of the lipogenic enzymes and suppress the enlargement of lipid droplets in BAs after denervation or thermoneutrality in male mice. These data provide insight into SCF/c-Kit signaling as a regulator that promotes lipid accumulation through the increase of lipogenic enzymes in BAT when thermogenesis is inhibited.