40 research outputs found
Changes in snow depth under elevationâdependent warming over the Tibetan Plateau
Abstract Snow plays an essential role in regulating climate change, the hydrological cycle, and various biological processes. Passive microwave snow depth data and gridded data from the Climate Research Unit (CRU_TS4.04) are utilized in this study to investigate spatiotemporal variations of snow depth over the Tibetan Plateau (TP), with special focus on the vertical dimension. The response of snow to elevationâdependent warming (EDW) is determined accordingly. High mountains experience more rapid warming than lower elevations. During 1980â2014, the total snow depth over the TP decreased; areas with the most significant decreasing trends are mainly concentrated in the northwestern and southwestern parts of the TP. The plateauâwide decrease in snow depth (â0.24âcm/decade) is mainly affected by increasing temperature (0.30°C/decade). The reduction in snow depth trend intensifies as subâregional mean elevation increases from 3,332âm (IID2) to 5,074âm (ID1). A stronger snow depth decrease in highâelevation subâregions generally corresponds to higher warming rates, which demonstrates EDW. The most pronounced correlation between snow depth decrease rate and elevation occurs in the southeastern TP, which covers the largest elevation range on the plateau (from 2,000 to 6,000âm)
Interannual variability of extreme precipitation in late summer over west China during 1961â2021
The characteristics and related mechanisms of the interannual variability of late summer (August) extreme precipitation in West China (WC) were investigated from 1961 to 2021. Precipitation and extreme precipitation (defined as the 99th percentile) generally decreased in the southeast-northwest direction, with a maximum in the Sichuan Basin. The non-linear trends in extreme precipitation have increased since the 1980s. Therefore, we further found that the interannual increase in extreme precipitation in the WC was significantly related to the eastward-strengthened South Asian high, western-stretched Western Pacific Subtropical high, enhanced westerly jet, anomalous cyclone in Mongolia, and anomalous anticyclone in the western Pacific. The anti-cyclonic anomaly is a Gill-type response to increase the sea surface temperature in the western Pacific. A mid-high latitude barotropic Rossby-wave train can be induced and has essential effects on the above key circulation patterns, further cooperating with the strong updrafts rather than strengthening and maintaining extreme precipitation in the WC
Protective role of curcumin in disease progression from non-alcoholic fatty liver disease to hepatocellular carcinoma: a meta-analysis
Background: Pathological progression from non-alcoholic fatty liver disease (NAFLD) to liver fibrosis (LF) to hepatocellular carcinoma (HCC) is a common dynamic state in many patients. Curcumin, a dietary supplement derived from the turmeric family, is expected to specifically inhibit the development of this progression. However, there is a lack of convincing evidence.Methods: The studies published until June 2023 were searched in PubMed, Web of Science, Embase, and the Cochrane Library databases. The SYstematic Review Center for Laboratory animal Experimentation (SYRCLE) approach was used to evaluate the certainty of evidence. StataSE (version 15.1) and Origin 2021 software programs were used to analyze the critical indicators.Results: Fifty-two studies involving 792 animals were included, and three disease models were reported. Curcumin demonstrates a significant improvement in key indicators across the stages of NAFLD, liver fibrosis, and HCC. We conducted a detailed analysis of common inflammatory markers IL-1ÎČ, IL-6, and TNF-α, which traverse the entire disease process. The research results reveal that curcumin effectively hinders disease progression at each stage by suppressing inflammation. Curcumin exerted hepatoprotective effects in the dose range from 100 to 400 mg/kg and treatment duration from 4 to 10 weeks. The mechanistic analysis reveals that curcumin primarily exerts its hepatoprotective effects by modulating multiple signaling pathways, including TLR4/NF-ÎșB, Keap1/Nrf2, Bax/Bcl-2/Caspase 3, and TGF-ÎČ/Smad3.Conclusion: In summary, curcumin has shown promising therapeutic effects during the overall progression of NAFLDâLFâHCC. It inhibited the pathological progression by synergistic mechanisms related to multiple pathways, including anti-inflammatory, antioxidant, and apoptosis regulation
Inhibition of Endothelial Cell Proliferation and Tumor Angiogenesis by Up-Regulating NDRG2 Expression in Breast Cancer Cells
The N-myc downstream-regulated gene 2 (NDRG2) is involved in tumor cell differentiation and apoptosis, but its function in tumor angiogenesis remains to be established. Here, we employed adenovirus overexpressing NDRG2 (Ad-NDRG2) to efficiently up-regulate target gene expression in the NDRG2-low-expressing, breast cancer cell line MCF-7. Moreover, VEGF secretion was decreased in MCF-7 cells infected by Ad-NDRG2, and medium conditioned by these infected cells could significantly inhibit the proliferation, tube formation and invasion of human umbilical vein endothelial cells (HUVECs). Further study indicated that the angiogenesis promoting factors VEGF and HIF-1α were down-regulated, whereas the angiogenesis suppressing factors p53 and VHL were up-regulated in MCF-7 cells infected by Ad-NDRG2. Finally, in a nude mouse model, intratumoral injections of Ad-NDRG2 every 3 days for 20 days significantly inhibited the growth and angiogenesis of xenografted MCF-7 tumors. In summary, these data indicate that NDRG2 may be involved in angiogenesis by impacting the expression of angiogenesis related factors. Thus, specific overexpression of NDRG2 by adenovirus represents a promising approach for the treatment of tumor angiogenesis
Seasonal and Regional Variability of Long-Wave Effective Radiation in China and Associated Modulating Factors
Variations in all-sky and clear-sky long-wave effective radiation (LER) in China during the period 2001â2016 were determined using monthly radiative datasets from the Clouds and the Earthâs Radiant Energy System (CERES). Annual and seasonal spatial distributions are found to be quite similar and show a decreasing trend from northwest to southeast, although highest values are found in spring. Mean LER under clear-sky conditions is approximately 20â30 Wmâ2 higher than that under all-sky conditions. There is a consistent downward trend in annual and seasonal variations of LER under different weather conditions in China especially after 2007. In northwest China, the eastern Tibetan Plateau, and southeast and northeast China, LER is significantly reduced in two weather conditions and this is more pronounced in spring. However, decreases in clear-sky LER are more obvious. Empirical orthogonal function (EOF) results for LER differences between all-sky conditions and clear-sky conditions were used to analyze regional characteristics and modulating factors. The first mode shows that the LER differences of two weather conditions over China become larger and significant after 2007. The second mode reflects the spatial characteristics, and four climate regions are divided according to the second pattern. According to the definition of LER, regression analysis shows that downward long-wave radiation has a greater influence on LER. When considering cloud effects and other modulating factors, LER has higher correlation with relative humidity in climate regions 3 and 4. However, there are higher negative correlations with middle and high clouds in regions 1 and 2, which are modulated by cloud characteristics. When these factors influence LER together, their correlation is significant in all regions (correlation coefficients are on average higher than 0.7). In summary, changes of LER can well reflect the change of climate system
Observed and Future Spatiotemporal Changes of Rainfall Extreme Characteristics and Their Dynamic Driver in June-August Season over Africa
Climate change has increased extreme events over globe and the most robust occurrences of concurrent drought and floods have become more common in Africa. This study focuses on the observed and projected analysis of rainfall extremes of consecutive dry day (CDD) and maximum monthly five day precipitation (RX5day) from Expert Team on Climate Change Detection and Indices (ETCCDI) in June-August season over Africa. The daily CORDEX Africa, reanalysis and CRU datasets were analyzed for extreme trends under RCP4.5 and RCP8.5 scenarios for the periods of 1980 to 2100. The spatiotemporal variability, trend, and magnitude of JJA seasonal rainfall performance exhibits a significant decreasing tendency over Eastern Africa compared to West Africa. The observed results of consecutive dry day (CDD) reveal that increasing trend and moreover RX5day shows that promising positive trend. Both rainfall extremes are influenced by the combined effect of large scale indexes and appear to be correlated negatively and positively with ENSO, NAO and AO. The CORDEX ensemble mean projections of JJA seasonal rainfall performance show a widespread significant change and the first mode of EOF depicts that 13.8% and 24.9% under the RCP4.5 and the highest variability is under RCP8.5 scenario. The projected CDD extreme exhibit an increasing trend in the coming periods and the percentage change revealed that increasing from 25.11%, 28.02% over West and 26.49%, 31.66% East Africa under RCP4.5 and RCP8.5 scenarios respectively. This situation will exacerbate increasing of frequent and intensified drought extremes over Africa. Additionally, the future RX5day indicated that mixed trend and revealed that increasing 3.72%, 2.54% over West and decreases -16.12%, -22.47% over East Africa under RCP4.5 and RCP8.5 respectively. Generally, rainfall extremes of CDD are projected to increase and RX5day shows a mixed trend in the coming periods over Africa and calls for further verification by using high resolution datasets
A TEST FOR IEEETRAN.CLS â [RUNNING ENHANCED CLASS V1.5] 1 Address-Free Memory Access Based on Program Syntax Correlation of Loads and Stores
Abstract â An increasing cache latency in next-generation processors incurs profound performance impacts in spite of advanced out-of-order execution techniques. One way to circumvent this cache latency problem is to predict load values at the onset of pipeline execution by exploiting either the load value locality or the address correlation of stores and loads. In this paper, we describe a new load value speculation mechanism based on the program syntax correlation of stores and loads. We establish a Symbolic Cache (SC), which is accessed in early pipeline stages to achieve a zero-cycle load. Instead of using memory addresses, the SC is accessed by the encoding bits of base register ID plus the displacement directly from the instruction code. Performance evaluations using SPEC95 and SPEC2000 integer programs on SimpleScalar simulation tools show that the SC achieves higher prediction accuracy in comparison with other load value speculation methods, especially when hardware resources are limited. I
Symbolic Cache: Fast Memory Access Based on Program Syntax Correlation of Loads and Stores
An increasing cache latency in next-generation processors incurs profound performance impacts in spite of advanced out-of-order execution techniques. One way to circumvent this cache latency problem is to predict load values at the onset of pipeline execution by exploiting either the load value locality or the address correlation of stores and loads. In this paper, we describe a new load value speculation mechanism based on the program syntax correlation of stores and loads. We establish a Symbolic Cache, which is accessed by the content of memory load and store instructions in early pipeline stages to achieve a zero-cycle load. Performance evaluation using SPEC95 and SPEC2000 integer programs with SimpleScalar tools shows that the symbolic cache provides higher accuracy than both the memory renaming and the value prediction scheme, especially when hardware resources are limited