The upper-tropospheric tropical easterly jet (TEJ) is one of the most important systems in modulating the Asian summer monsoon rainfall. In addition to the intensity variability that has been ...extensively studied, the TEJ’s core experiences remarkable changes in the zonal and meridional directions. The TEJ can be identified as three locational patterns using the cluster analysis: the east, northwest, and southwest modes. The frequencies of the three locational modes exhibit discernable changes on the monthly and the interannual-decadal time scales. While the anomalous zonal divergent circulation with the convergent/divergent center over the tropical Indian Ocean (IO) determines the zonal location of the TEJ’s core, the meridional temperature gradient between the Eurasian continent and the tropical IO distinguishes the meridional location of the TEJ’s core. It reflects the fundamental role of the large-scale east-west and north-south thermal contrasts in the movement of the TEJ’s core location. The variability of the TEJ’s core location has distinct impacts on the summer monsoon precipitation via redistributing the upper-level divergence and modulating the monsoon meridional circulation, especially in South, Southeast, and East Asia. In conjunction with the thermal effect of the Tibetan Plateau, the meridional shift of the TEJ’s core can affect the precipitation along the south slope of the Tibetan Plateau. These findings highlight the cause of the diversified TEJ’s core location and the significant impacts on the summer monsoon rainfall.
The sea‐ice extent (SIE) in the Weddell Sea plays a crucial role in the Antarctic climate system. Many studies have examined its long‐term trend, however whether its year‐to‐year variation has ...changed remains unclear. We found an amplified year‐to‐year variance of the Weddell Sea SIE in austral summer since 1998/1999 in observational datasets. Analyses of sea‐ice concentration budget and surface fluxes indicate that it is the thermodynamic process that drives the amplification of SIE variations, rather than the sea‐ice‐drift‐related dynamic process. Compared to 1979–1998, the Southern Annular Mode in the preceding spring shows a closer linkage with the Weddell Sea SIE in 1999–2021 through a stronger and more prolonged impact on sea surface temperature, which thermodynamically modulates local sea ice via changing surface heat and radiation fluxes. Our study helps advance the understanding of extreme low Antarctic‐SIE records occurring in recent decades and improve future projections of the Antarctic sea‐ice variability.
Plain Language Summary
Unlike Arctic sea ice, which has significantly declined in recent decades, Antarctic sea ice possesses a moderate increase with large spatial and seasonal discrepancies. The amount of austral‐summer sea ice extent (SIE) around the Antarctica exhibits more pronounced year‐to‐year variations in the 21st century. Interestingly, we found that the amplified SIE variation is most significant in the Weddell Sea, east of the Antarctic Peninsula. This amplified variations in Weddell Sea SIE apparently cannot be fully explained by anthropogenic forcing, suggesting an important role of internal variability in the Antarctic climate system. Our analyses showed that the late‐1990s changes in the Southern Annular Mode (SAM)—the predominant mode of climate variability in the extratropical Southern Hemisphere—might cause the interdecadal amplification of the summer sea‐ice variation in the Weddell Sea via the thermodynamic process.
Key Points
The year‐to‐year variability of summer sea‐ice extent in the Weddell Sea, Antarctica, has significantly increased since 1998/1999
This interdecadal change in sea‐ice extent is dominated by changes in thermodynamic process rather than dynamic and mechanical processes
The Southern Annular Mode contributes to such a sea‐ice change via altering sea surface temperature and thus local thermodynamic processes
Stem cell transplantation is a promising method in the treatment of spinal cord injury (SCI). Researches have shown that stem cell-derived exosomes as well as its contents such as microRNAs ...contribute to the protective effects of stem cell against SCI. However, the effects of exosomes derived from bone marrow stem cells on SCI and the underlying mechanisms remain unknown. In this study, we collected bone marrow stem cells derived exosomes (BMSCs-exo) to deal with SCI rats and LPS induced microglia to explore the possible mechanisms. We found that BMSCs-exo showed significant effects on decreasing pro-inflammatory cytokines as well as increasing Basso–Beattie–Bresnahan score after acute SCI. MicroRNA-181c levels in tissue were elevated with the use of BMSCs-exo. Then we verified the effect in vitro and found that in LPS induced microglia, the administration of BMSCs-exo could inhibit the expression of pro-inflammatory cytokines, and the phosphorylation of NF-κB signal was also suppressed. During which, the expression of microRNA-181c in microglia was elevated. When LPS induced microglia were treated with BMSCs-exo over-expressing microRNA-181c, the levels of pro-inflammatory cytokines decreased. Then bioinformatics techniques were used to detect the possible target gene of microRNA-181c and then PTEN was found as a candidate. Further experiments showed that the protection effects of BMSCs-exo over-expressing microRNA-181c could be antagonized by the elevation of PTEN expression both in vitro and in vivo. In conclusion, we verified that BMSCs-exo could protect against SCI through its content microRNA-181c which suppressed the inflammation in microglia and spinal cord. It was related to the inhibition of PTEN and the suppression of NF-κB signal, and finally decreasing inflammation and apoptosis in spinal cord and improved SCI.
The interdecadal enhancement in the interannual variability of summer monsoon meridional circulation (SMMC) over the South China Sea around the early 1990s is investigated. Results show the change in ...the SMMC variability may arise from the interdecadal shift in the leading modes of low-level geopotential height over East Asia–Australia and Indo–Pacific sea surface temperature anomalies (SSTAs) in boreal summer. Before the early 1990s, the leading mode of Indo–Pacific SSTAs shows a zonal tripole pattern, with abnormally warm eastern Pacific and northern Indian Ocean and cold western Pacific. At the lower level, the western North Pacific cooling and northern Indian Ocean warming generate an anticyclonic anomaly over western North Pacific, while the cooling over the Maritime Continent and east of Australia favors an abnormal anticyclone over Australia. Hence region-wide positive geopotential height anomalies cover East Asia–Australia, which resemble the major mode of geopotential height and generate weak south–north pressure gradient and SMMC variability. After the early 1990s, the leading SSTAs mode shifts to a zonal dipole with abnormally cold western Pacific and warm equatorial central–eastern Pacific. The central Pacific warming induces an anomalous low-level cyclone over Philippines and it is further maintained by the Maritime Continent cooling. Meanwhile, the cooling over the east of Australia and Maritime Continent favors an abnormal Australian anticyclone. The low-level geopotential height thus shows south–north dipole anomalies over East Asia–Australia, resembling its major mode and generating obvious meridional pressure gradient and SMMC variability. The atmospheric responses to different SSTAs modes are confirmed by CAM4 experiments.
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•The mantle source for Eocene mafic rocks was the asthenospheric mantle with the recycled oceanic crust.•The mantle source for Miocene mafic rocks was the (asthenospheric or ...lithospheric) mantle with continental crust.•Evolution from oceanic to continental crust subduction in southern Tibet was recorded in the Cenozoic mafic rocks.
We collated existing data for the Eocene Langshan mafic rocks (Eocene mafic rocks) and the Miocene potassic–ultrapotassic mafic rocks (Miocene mafic rocks) in southern Tibet to investigate the tectonic transition from Neo-Tethyan oceanic crust subduction to Indian continental crust subduction. The Eocene mafic rocks have high Na2O contents (K2O/Na2O = 0.03–0.2) and show OIB-like trace element patterns (e.g., positive Nb and Ta anomalies) and depleted radiogenic Sr–Nd isotope compositions (87Sr/86Sr of apatite = 0.7031, εNd(t) = +5.1 to +6.1). In contrast, the Miocene mafic rocks have high K2O contents (K2O/Na2O = 1.9–8.5) and exhibit arc-like trace element patterns (enrichment in LILEs and depletion in HFSEs) and enriched radiogenic Sr–Nd isotope compositions (87Sr/86Sr = 0.7115–0.7362, εNd(t) = −16 to −12.4). The mantle source for the Eocene mafic rocks was generated by reactions between asthenospheric mantle wedge and felsic melts from subducted Neo-Tethyan oceanic crust (outside the field of rutile stability). In contrast, the mantle source of the Miocene mafic rocks was generated by reactions between asthenospheric (or lithospheric) mantle wedge and felsic melts from subducted Indian continental crust. Taking into account the regional tectonic evolution, we propose that break-off of the Neo-Tethyan oceanic slab and roll-back and/or break-off of the Indian continental slab were the most likely geodynamic mechanisms that led to the production of the Eocene and Miocene mafic rocks, respectively. Therefore, the transition from the Eocene to Miocene mafic rocks in southern Tibet provides an opportunity to understand the tectonic transition from Neo-Tethyan oceanic to Indian continental crust subduction.
Ellagic acid (EA) was reported to play protective roles in rheumatoid arthritis (RA). It was found that the level of metastasis-associated gene 1 (MTA1)/histone deacetylase 1 (HDAC1) protein complex ...was downregulated by polyphenols in several human disorders. Notably, inhibition of MTA1 or HDAC1 has anti-inflammatory effects on RA. Therefore, our study is aimed at investigating whether EA prevents RA progression through regulating the MTA1/HDAC1 complex. Herein, the human fibroblast-like synoviocyte (FLS) cell line MH7A was treated with TNF-α to induce an inflammation model in vitro and then incubated with different concentrations of EA. Western blot analysis showed that EA reduced MTA1 expression in a dose-dependent manner in MH7A cells. Then, TNF-α-treated MH7A cells were incubated with EA alone or together with MTA1 overexpression plasmid (pcDNA-MTA1), and we found that EA inhibited proliferation, inflammation cytokine levels, and oxidative stress marker protein levels and promoted apoptosis in MH7A cells, while MTA1 overexpression abolished these effects. Moreover, coimmunoprecipitation assay verified the interaction between MTA1 and HDAC1. EA downregulated the MTA1/HDAC1 complex in MH7A cells. MTA1 knockdown inhibited proliferation, inflammation, and oxidative stress and promoted apoptosis in MH7A cells, while HDAC1 overexpression reversed these effects. Moreover, chromatin immunoprecipitation assay indicated that EA inhibited HDAC1-mediated Nur77 deacetylation. Rescue experiments demonstrated that Nur77 knockdown reversed the effects of EA on MH7A cell biological behaviors. Additionally, EA treatment attenuated arthritis index, paw swelling, synovial hyperplasia, and inflammation in collagen-induced arthritis (CIA) rats. In conclusion, EA inhibited proliferation, inflammation, and oxidative stress and promoted apoptosis in MH7A cells and alleviated the severity of RA in CIA rats though downregulating MTA1/HDAC1 complex and promoting HDAC1 deacetylation-mediated Nur77 expression.
Farmland loss in drastically urbanizing landscapes has long been a research concern for resource management, landscape planning, and spatial governance, especially in the context of China. In recent ...years, the issue of urbanization-associated farmland loss (UAFL) seems to be increasingly recognized as relevant to sustainability. To date, however, existing studies have not yet comprehensively addressed the research gap between UAFL and sustainability. Here, we aim to help fill this knowledge gap by considering UAFL research as an example of the broader land/landscape-related literature, in a hope of informing future studies to better advance sustainability through land-related approaches. Specifically, we combined bibliometric analyses with code-based content analysis to reveal the knowledge base, thematic evolution, and historiographic paths of the literature on UAFL across China and the empirical case studies’ relevance to sustainability. Our main findings include: (1) the examined literature barely draws insights from sustainability science and sustainability only started to arise as a notable topic at around 2016; (2) over half of the empirical studies show awareness in advancing sustainability and interest in understanding the social-environmental drivers and processes underlying landscape dynamics, yet few demonstrate methodological transdisciplinarity; (3) those sustainability-relevant studies either frame UAFL as depletion of the farmland resource that may threat China’s food security and consequently hinder sustainable urbanization or frame UAFL as part of widespread landscape dynamics that affect the environmental outcome(s) or social–environmental tradeoffs of landscape multi-functions; and (4) existing empirical studies are disproportionately focused on 1991–2006, national, regional, and city scales, and some of China’s most developed areas. Our findings provide an overview of this specific research avenue on UAFL and, more importantly, point to the imperative for land/landscape scholars to break out of their disciplinary silos, especially in the natural sciences, to generate more actionable sustainability insights.
Study of resource and environmental carrying capacity is an important research content of sustainable development science and the theoretical support for land space optimization. Existing research ...theories need to be deepened, and spatial simulation studies are relatively lacking. This study aimed to assess the current and future resource and environmental carrying capacity in the Yangtze River Delta region’s coastal zone and enhance sustainable development by exploring the application of shared socioeconomic pathway (SSPs) scenarios at the spatial pattern scale in regional resource and environmental carrying capacity simulation studies. Based on the FLUS and InVEST models, this study introduced the Coastal Resource and Environmental Carrying Capacity Index (CRECC) from the dimensions of “pressure” and “support” using land use remote sensing monitoring data and SSPs scenario data. A CRECC evaluation index system and quantitative evaluation method for the Yangtze River Delta were constructed. The results showed that from 2000 to 2020, the CRECC of the Yangtze River Delta coastal zone increased, the carrying capacity decreased, and the spatial distribution was low in the north and high in the south. The carrying capacity under the five SSP scenarios did not improve. The mismatch between natural ecological conditions and the intensity of human activities in the shoreline area was more prominent than in the study area, with the SSP1 and SSP5 scenarios being the most obvious. The supporting indicators have a more significant influence on improving CRECC than the pressure indicators, among which the supply capacity of water resources, land resources, and atmospheric environmental quality are the main limiting factors in the process of future sustainable economic-ecological development. This study provides ideas and examples for exploring spatial and temporal predictions of resources and environmental carrying capacity in coastal zones.
Cognitive impairment is a well-defined complication of chronic kidney disease (CKD), but the neural mechanisms are largely unknown.
The study aimed to assess white matter (WM) microstructure changes ...and their relationship with cognitive impairment development during CKD progression.
Diffusion tensor imaging (DTI) datasets were acquired from 38 patients with CKD (19 patients were at stage 3; 19 patients were at stage 4) and 22 healthy controls (HCs). Tract-based spatial statistics (TBSS) was implemented to assess the differences in WM integrity among the three groups. The associations between abnormal WM integrity and clinical indicators (digit symbol test scores, the type A number connection test scores, hemoglobin, serum urea, serum creatinine, serum calcium, and serum potassium levels) were also computed.
Compared with patients with CKD at stage 3 and HCs, patients with CKD at stage 4 showed significantly lower fractional anisotropy (FA) and higher mean diffusivity (MD) in the corpus callosum (CC), anterior thalamic radiation, inferior fronto-occipital fasciculus, and inferior longitudinal fasciculus. Correlation analysis showed that the MD in the genu of CC was negatively associated with the digit symbol test scores (
= -0.61,
= 0.01), and the FA in the left anterior thalamic radiation was positively associated with the level of serum calcium (
= 0.58,
= 0.01).
Patients with non-end-stage CKD have multiple abnormalities in WM regions. DTI metrics change with the progression of CKD and are primarily associated with cognitive impairment. The reduced integrity of WM tracts may be related to a low level of blood calcium.
Land use multifunctionality (LUMF) is a pragmatic means of resolving land use conflicts and realising regional sustainability and has critical importance in land system science. In this study, we ...constructed LUMF classifications from a sustainable perspective and quantified and analysed the deliveries of land use functions (LUFs) in the coastal area of Jiangsu Province, China. On this basis, the “bundle” concept was innovatively introduced into the LUMF research framework to analyse the spatiotemporal effects of trade-offs and synergies among multiple LUFs. The results showed that high-value LUF geographic units tended to cluster in human-dominated landscapes. During the study period (2000–2018), the average provision of regional multifunction increased slightly, while the subfunctions changed in different trends. Four LUF bundles (agricultural zone, mosaic cropland–rural housing zone, coastal natural and seminatural landscape zone, urban development zone) were identified, each having different dominant LUFs and landscape configurations. In each LUF bundle, the most common trade-offs were observed in the environmental and economic functions. The space incompatibilities caused by land development demand in different subregions created a trade-off and synergy among multiple functions. Moreover, LUF relations were not static over time, owing to the effects of urbanisation, coastal reclamation activities, and agriculture protection policies. Based on the above results, this research proposes land use optimisations for different multifunctional areas.
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