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- 2019
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Tidskriftsartikel (refereegranskat)
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| 2. |
- Feng, X. Y., et al.
(författare)
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Tree-ring cellulose oxygen isotopes indicate atmospheric aridity in the western Kunlun Mountains
- 2022
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Ingår i: Ecological Indicators. - : Elsevier BV. - 1470-160X. ; 137
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Tidskriftsartikel (refereegranskat)abstract
- As an important indicator of atmospheric aridity, the vapor pressure deficit (VPD) is being paid increasing attention in global change researches during recent decades. However, available proxy data with the capability to represent VPD is still scarce in the globe. Herein we demonstrated a "hidden " frequency-dependent indication of tree-ring cellulose oxygen isotope (delta(OTRC)-O-18) to atmospheric aridity in the western Kunlun Mountains, Central Asia. In applying correlation and partial correlation analysis, frequency-dependent climatic drivers triggering the delta(OTRC)-O-18 values were detected. For the raw data with inter-decadal variability, delta(OTRC)-O-18 variations mainly indicated May-August precipitation (Local: r = -0.59, p < 0.001; Moisture source: r = -0.53, p < 0.001), evapotranspiration (ET) (Local: r = -0.57, p < 0.001; Moisture source: r = -0.51, p < 0.001). After a 5-year high-pass filter, the delta(OTRC)-O-18 series revealed highly significant correlation with May-August VPD (Local: r = 0.82, p < 0.001; Moisture source: r = 0.80, p < 0.001). The partial correlation further confirmed the strong linkages with high-frequency VPD when the impact of any additional eco-climatological variable (precipitation, temperature, ET, soil moisture 0-40 cm) was excluded. In contrast, if the effect of May-August VPD was excluded, relationships between delta(OTRC)-O-18 and other variables turned insignificant. Collectively, it was concluded that delta 18OTRC from the western Kunlun Mountains may indicate VPD at timescales < 5 years. Our results suggest that frequency dependent climatic significances should be considered when interpreting multi-process determined delta(OTRC)-O-18 as a climate-proxy.
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| 3. |
- Gao, Shengjun, et al.
(författare)
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Urbanization-induced warming amplifies population exposure to compound heatwaves but narrows exposure inequality between global North and South cities
- 2024
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Ingår i: NPJ CLIMATE AND ATMOSPHERIC SCIENCE. - 2397-3722. ; 7:1
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Tidskriftsartikel (refereegranskat)abstract
- Urban populations face heightened extreme heat risks attributed to urban heat islands and high population densities. Although previous studies have examined global urban population exposure to heatwaves, the influence of urbanization-induced warming is still not quantified. Here, leveraging satellite-derived near-surface air temperature data, we assess the impacts of urbanization-induced warming on heat exposure in 1028 cities worldwide. Additionally, we investigate its role in shaping disparities in heat exposure between global North and South cities. Our findings reveal that urbanization-amplified compound heatwaves exacerbate heat exposure risk in more than 90% of cities, and that this amplification is stronger in high urbanization areas. Moreover, our analysis highlights the potential for overestimating disparities between global North and South cities if urbanization-induced warming is overlooked. The inequality of higher heat exposure in the global South cities than in the global North cities will be narrowed in real scenarios due to more intense urbanization-induced warming in the global North cities. We emphasize the pivotal role of urbanization-induced heatwave intensification in heat exposure assessments and call for its inclusion in future population vulnerability evaluations to extreme heat.
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| 4. |
- Jiang, Qiyun, et al.
(författare)
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Development and Validation of a Risk Score Screening Tool to Identify People at Risk for Hypertension in Shanghai, China.
- 2022
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Ingår i: Risk management and healthcare policy. - 1179-1594. ; 15, s. 553-562
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Tidskriftsartikel (refereegranskat)abstract
- This study aimed to develop a screening tool based on a risk scoring approach that could identify individuals at high risk for hypertension in Shanghai, China.A total of 3147 respondents from the 2013 Shanghai Chronic Disease and Risk Factor Surveillance were randomly divided into the derivation group and validation group. The coefficients obtained from multivariable logistic regression were used to assign a score to each variable category. The receiver operating characteristic (ROC) curve was used to find the optimal cut-off point and to evaluate the screening performance.Age, family history of hypertension, having diabetes, having dyslipidemia, body mass index, and having abdominal obesity contributed to the risk score. The area under the ROC curve was 0.817 (95% CI: 0.797-0.836). The optimal cut-off value of 20 had a sensitivity of 83.4%, and a specificity of 64.3%, demonstrating good performance.We developed a simple and valid screening tool to identify individuals at risk for hypertension. Early detection could be beneficial for high-risk groups to better manage their conditions and delay the progression of hypertension and related complications.
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| 5. |
- Ren, Zhihui, et al.
(författare)
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Temporal Scaling Characteristics of Sub-Daily Precipitation in Qinghai-Tibet Plateau
- 2024
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Ingår i: EARTHS FUTURE. - 2328-4277. ; 12:3
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Tidskriftsartikel (refereegranskat)abstract
- The Qinghai-Tibet Plateau (QTP) is highly susceptible to destructive rainstorm hazards and related natural disasters. However, the lack of sub-daily precipitation observations in this region has hindered our understanding of rainstorm-related hazards and their societal impacts. To address this data gap, a new approach is devised to estimate sub-daily precipitation in QTP using daily precipitation data and geographical information. The approach involves establishing a statistical relationship between daily and sub-daily precipitation based on data from 102 observation sites. This process results in a set of functions with six associated parameters. These parameters are then modeled using local geographical and climatic information through a machine learning algorithm called support vector regression. The results indicated that the temporal scaling characteristics of sub-daily precipitation can be accurately described using a logarithmic function. The uncertainty of the estimates is quantified using the coefficient of variance and coefficient of skewness, which are estimated using a logarithmic and linear curve, respectively. Additionally, the six parameters are found to be closely linked to geographical conditions, enabling the creation of a 1-km parameters data set. This data set can be utilized to quantitatively describe the probabilistic distribution and extract key information about maximum precipitation duration (from 1 to 12 hr). Overall, the findings suggest that the generated parameters data set holds significant potential for various applications, including risk analysis, forecasting, and early warning for rainstorm-related natural disasters in QTP. The innovative method developed in this study proves to be an effective approach for estimating sub-daily precipitation and assessing its uncertainty in ungauged regions. As one of famous hotspots for natural disaster studies on Earth, the Qinghai-Tibet Plateau (QTP) is highly vulnerable to destructive rainstorm hazard and related natural disasters, causing significant damage to property, infrastructure, agriculture, and resulting in extensive loss of life. Short-duration heavy precipitation at sub-daily scales is an important trigger for flash flood, debris flows and other disasters in QTP. However, it is a poorly gauged high mountain region, observed data for sub-daily precipitation is extremely limited. Although there have been several satellite products and reanalysis data for sub-daily precipitation in QTP, their quality has large bias and uncertainty compared to observations. It leaves a large data gap of sub-daily precipitation, hindering the studies of rainstorm-related natural disasters in the region. In this work, we develop a new strategy to quantify the temporal scaling characteristics of sub-daily precipitation, as a basis of temporal downscaling. Then we use the new strategy to generate a parameters data set, to fill the data gap of sub-daily precipitation in QTP. The parameters data set generated provides an effective way to estimate sub-daily precipitation and its uncertainty, which can effectively serve for the rainstorm-related natural disasters study in QTP. A high-resolution gridded parameters data set is generated to estimate sub-daily precipitation and its uncertainty in QTP The temporal scaling characteristics of sub-daily precipitation in QTP is well described by a logarithmic function Spatial heterogeneity in the temporal scaling characteristics of sub-daily precipitation in QTP is closely related to geographical conditions
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| 6. |
- Tan, Youwen, et al.
(författare)
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The naturally occurring YMDD mutation among patients chronically infected HBV and untreated with lamivudine: A systematic review and meta-analysis
- 2012
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 7
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Recension (övrigt vetenskapligt/konstnärligt)abstract
- Background: Several recent reports have demonstrated that tyrosine (Y)-methionine (M)-aspartic acid (D)-aspartic acid (D) (YMDD) motif mutations can naturally occur in chronic HBV patients without antiviral treatment such as lamivudine therapy. This paper aims to assess the overall spontaneous incidence and related risk factors of YMDD-motif mutations among lamivudine-naïve chronic HBV carriers, so as to provide some clue for clinical treatment of hepatitis B. Methodology/Principal Findings: Chinese and English literatures were searched for studies reporting natural YMDD mutations among untreated chronic HBV patients from 2001 to 2010. The incidence estimates were summarized and analyzed by meta-analyses. Forty-seven eligible articles from eight countries were selected in this review (13 in English and 34 in Chinese). The pooled incidence of YMDD-motif mutation among untreated chronic HBV patients from eight countries was 12.21% (95% CI: 9.69%-14.95%). China had an incidence of 13.38% (95% CI: 10.90%-16.07%) and seven other countries had an incidence of 9.90% (95% CI: 3.28%-19.55%), respectively. Lamivudine therapy would increase the risk of mutations 5.23 times higher than the untreated patients. A higher HBV DNA copy number was associated with increased incidence of natural YMDD mutation. No significant difference was found in YMDD mutation incidence between groups of different gender, age, HBeAg status, patients' ALT (alanine aminotransferase) level, and between the groups of HBV genotype B and C. Conclusions: The YMDD-motif mutations can occur spontaneously with a relatively high incidence in CHB patients untreated with lamivudine. These mutations might be the consequence of accumulated base mismatch due to the nature of viral polymerase. More fundamental and clinical studies are needed to clarify the influence of YMDD mutations in hepatitis B progression and antiviral treatment. © 2012 Tan et al.
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