Tree-ring width(RW),density,elemental com-position,and stable carbon and oxygen isotope(δ^(13)C,δ^(18)O)are widely used as proxies to assess climate change,ecology,and environmental pollution;however,a specific pret...Tree-ring width(RW),density,elemental com-position,and stable carbon and oxygen isotope(δ^(13)C,δ^(18)O)are widely used as proxies to assess climate change,ecology,and environmental pollution;however,a specific pretreat-ment has been needed for each proxy.Here,we developed a method by which each proxy can be measured in the same sample.First,the sample is polished for ring width meas-urement.After obtaining the ring width data,the sample is cut to form a 1-mm-thick wood plate.The sample is then mounted in a vertical sample holder,and gradually scanned by an X-ray beam.Simultaneously,the count rates of the fluorescent photons of elements(for chemical characteriza-tion)and a radiographic grayscale image(for wood density)are obtained,i.e.the density and the element content are obtained.Then,cellulose is isolated from the 1-mm wood plate by removal of lignin,and hemicellulose.After producing this cellulose plate,cellulose subsamples are separated by knife under the microscope for inter-annual and intra-annual stable carbon and oxygen isotope(δ^(13)C,δ^(18)O)analysis.Based on this method,RW,density,elemental composition,δ^(13)C,and δ^(18)O can be measured from the same sample,which reduces sample amount and treatment time,and is helpful for multi-proxy comparison and combination research.展开更多
Using five well-replicated Qilian juniper (Sabina przewalskii Kom.) tree-ring width index se- ries, monthly normalized difference vegetation index (NDVI) of grassland, and climatic data from 1982 to 2001, the relation...Using five well-replicated Qilian juniper (Sabina przewalskii Kom.) tree-ring width index se- ries, monthly normalized difference vegetation index (NDVI) of grassland, and climatic data from 1982 to 2001, the relationships between tree-ring width index, NDVI of grassland, and climatic data were analyzed firstly. Then, the relationship between tree-ring width index and NDVI of grassland was explored. The re- sults showed that: (1) Temperature and precipitation in June influenced tree-ring width index and NDVI of grassland deeply in Delingha. (2) There were sig- nificant relationships between five tree-ring width index series (DLH1-DLH5) and monthly NDVI of grassland from June to September, with the most significant relationship being between tree-ring width index series and NDVI of grassland in August. (3) The PC1 (the first principal component derived from DLH1-DLH5 series) exhibited good agreement with monthly NDVI of grassland in the grass growth sea- son (from June to September) and the averaged NDVI in the growth season, which was attributed to their common responses to water-supply limit in Delingha. This study may allow an increase in studying the past dynamics of grassland in Delingha in that the variation of grassland NDVI during the last millennium has been reconstructed from PC1.展开更多
Tree-ring standardized chronologies are developed by 78 cores collected from the eastern and western Helan Mountain. Statistical analysis shows that both the STD and RES chronologies correlate negatively with the temp...Tree-ring standardized chronologies are developed by 78 cores collected from the eastern and western Helan Mountain. Statistical analysis shows that both the STD and RES chronologies correlate negatively with the temperature of different periods of early half year, especially with January to August mean (JA) temperature, which means that JA temperature is one of the predominant limiting factors of tree growth in the Helan Mountain. Based on this analysis, we reconstructed JA temperature, and the explained variance is 43.3% (F=21.422, p〈0.001 ). The comparatively high temperature periods in the reconstruction were: 1805-1818 1828-1857, 1899-1907, 1919-1931 and 1968-1995; and the comparatively low temperatu re periods happened in 1858-1872, 1883-1895 and 1935-1953. Ten-year moving average curve shows three slow uplifting trends: 1766-1853, 1862-1931 and 1944-1995. Each temperature increase was followed by a sudden temperature decrease about 10 years, that is to say, the JA temperature in the Helan Mountain is characterized by slow increase and sudden decrease. The 70- and 10.77-year periodicities detected in the temperature series correspond to the Gleissberg (80-year) and Schwabe (11-year) periodicities of solar activity respectively, the 2.11-2.62 years cycles are considered to be influenced by QBO (Quasi-Biennial-Oscillation) and the local environmental change.展开更多
Based on the analysis of the correlation between the tree-ring width of Pinus tabulaeformis and the climate factors in the western Hedong sandy land of Ningxia, a conversion equation between the annual precipitation a...Based on the analysis of the correlation between the tree-ring width of Pinus tabulaeformis and the climate factors in the western Hedong sandy land of Ningxia, a conversion equation between the annual precipitation and the tree-ring width since 1899 was reconstructed. The results of cross verification indicated that the conversion equation is stable and the reconstructed results are reliable. The result of reconstructed annual precipitation showed the remarkable fluctuation of precipitation and dry-to-wet variation before the 1940s. The smaller fluctuation and high frequent changes of precipitation occurred during the period of 1940s-1980s and after the 1980s the change trend of the precipitation became high periodic extent and low frequent. The study found that there were some coincidences with the climate change in Changling Mountains, Helan Mountains and the east of Qilian Mountains. The relatively dry periods in the beginning of 20th century, 1920s to 1930s, the end of the 20th century and 2004 to 2006 in the western Hedong sandy land of Ningxia accelerated the desertification, while the relatively humid period during the periods of the 1910s-1920s, 1930s-1940s and 1990s is favorable to prevent and control the desertification, and to weaken the climate warming and drying. The periods of annual precipitation variation in the western Hedong sandy land of Ningxia since 1899 are approximately 2-4 years, 5-7 years and 10 years.展开更多
Regional tree-ring width chronology of the Scots pine (Pinus sylvestris L.) was constructed from 8 sites in the forest-steppe belt situated in the foothills of the Selenga River basin, Russia. Moisture information con...Regional tree-ring width chronology of the Scots pine (Pinus sylvestris L.) was constructed from 8 sites in the forest-steppe belt situated in the foothills of the Selenga River basin, Russia. Moisture information contained in tree-ring width chronology was obtained through linear regression reconstruction models of annual August–July precipitation and annual water discharge of the Selenga River during the period 1767–2015. Comparison of the smoothed series allowed estimating long-term variation component of these moisture regime parameters with a high precision. At the same time, regional drought indices are less correlated with pine radial growth, because they have contribution of the other environmental variables, which are much less reflected in the tree-ring of the investigated pine forest stands. Reconstructed dynamic of the moisture regime parameters is supported by documental evident of many socially significant events in the regional history, such as crop failures caused by both droughts and floods, and catastrophic fire in the Irkutsk City in 1879. Also, dependence of the amount of precipitation in the study area on the atmospheric circulation in Central Asia is revealed to have a similar pattern with other regions, i.e., a negative relationship of precipitation with the development of large high atmospheric pressure area within its center in the Altai and Tianshan mountains.展开更多
August-June precipitation has been reconstructed back to AD 1720 for the northern Greater Higgnan Mountains, China, by use ofPinus sylvestris var. mongolica tree-ring width. The reconstruction explains the variance of...August-June precipitation has been reconstructed back to AD 1720 for the northern Greater Higgnan Mountains, China, by use ofPinus sylvestris var. mongolica tree-ring width. The reconstruction explains the variance of 39% in observed precipitation from 1973 to 2008. Some extremely dry/wet signals in historical documents and other precipitation reconstructions in previous studies are precisely captured in our reconstruction. Wet periods occurred during the periods of 1730 to 1746, 1789 to 1812, 1844 to 1903, 1920 to 1930, 1942 to 1961, and 1985 to 1998; while periods of 1747 to 1788, 1813 to 1843, 1904 to 1919, 1931 to 1941, and 1962 to 1984 were relatively dry. Power spectral and wavelet analyses demon- strated the existence of significant 24-year, 12-year, and 2-year cycles of variability.展开更多
Reconstructing the hydrological change based on dendrohydrological data has important implications for understanding the dynamic distribution and evolution pattern of a given river. The widespread, long-living conifer...Reconstructing the hydrological change based on dendrohydrological data has important implications for understanding the dynamic distribution and evolution pattern of a given river. The widespread, long-living coniferous forests on the Altay Mountains provide a good example for carrying out the dendrohydrological studies. In this study, a regional composite tree-ring width chronology developed by Lariat sibirica Ledeb. and Picea obovata Ledeb. was used to reconstruct a 301-year annual (from preceding July to succeeding June) streamflow for the Haba River, which originates in the southern Altay Mountains, Xinjiang, China. Results indicated that the reconstructed streamflow series and the observations were fitting well, and explained 47.5% of the variation in the observed streamflow of 1957-2008. Moreover, floods and droughts in 1949-2000 were precisely captured by the streamflow reconstruction. Based on the frequencies of the wettest/driest years and decades, we identified the 19th century as the century with the largest occurrence of hydrological fluctuations for the last 300 years. After applying a 21-year moving average, we found five wet (1724-1758, 1780-1810, 1822-1853, 1931-1967, and 1986-2004) and four dry (1759-1779, 1811-1821, 1854-1930, and 1968-1985) periods in the streamflow reconstruction. Furthermore, four periods (1770-1796, 1816-1836, 1884-1949, and 1973-1997) identified by the streamflow series had an obvious increasing trend. The increasing trend of streamflow since the 1970s was the biggest in the last 300 years and coincided with the recent warming-wetting trend in northwestern China. A significant correlation between streamflow and precipitation in the Altay Mountains indicated that the streamflow reconstruction contained not only local, but also broad-scale, hydro-climatic signals. The 24-year, 12-year, and 2.2-4.5-year cycles of the reconstruction revealed that the streamflow variability of the Haba River may be influenced by solar activity and the atmosphere-ocean system.展开更多
Tree-ring width chronologies of Larix chinensis were developed from the northern and southern slopes of the Qinling Mountains in Shaanxi Province,and climatic factors affecting the tree-ring widths of L.chinensis were...Tree-ring width chronologies of Larix chinensis were developed from the northern and southern slopes of the Qinling Mountains in Shaanxi Province,and climatic factors affecting the tree-ring widths of L.chinensis were examined.Correlation analysis showed that similar correlations between tree-ring width chronologies and climatic factors demonstrated that radial growth responded to climate change on both slopes.The radial growth of L.chinensis was mainly limited by temperature,especially the growing season.In contrast,both chronologies were negatively correlated with precipitation in May of the previous year and April of the current year.Spatial climate-correlation analyses with gridded land-surface climate data revealed that our tree-ring width chronologies contained a strong regional temperature signal over much of northcentral and eastern China.Spatial correlation with seasurface temperature fields highlights the influence of the Pacific Ocean,Indian Ocean,and North Atlantic Ocean.Wavelet coherence analysis indicated the existence of some decadal and interannual cycles in the two tree-ring width chronologies.This may suggest the influences of El Nin˜o-Southern Oscillation and solar activity on tree growth in the Qinling Mountains.These findings will help us understand the growth response of L.chinensis to climate change in the Qinling region,and they provide critical information for future climate reconstructions based on this species in semi-humid regions.展开更多
BACKGROUND Compared with patients with other causes of acute pancreatitis,those with hypertriglyceridemia-induced acute pancreatitis(HTG-AP)are more likely to develop persistent organ failure(POF).Therefore,recognizin...BACKGROUND Compared with patients with other causes of acute pancreatitis,those with hypertriglyceridemia-induced acute pancreatitis(HTG-AP)are more likely to develop persistent organ failure(POF).Therefore,recognizing the individuals at risk of developing POF early in the HTG-AP process is a vital for improving outcomes.Bedside index for severity in acute pancreatitis(BISAP),a simple parameter that is obtained 24 h after admission,is an ideal index to predict HTG-AP severity;however,the suboptimal sensitivity limits its clinical application.Hence,current clinical scoring systems and biochemical parameters are not sufficient for predicting HTG-AP severity.AIM To elucidate the early predictive value of red cell distribution width(RDW)for POF in HTG-AP.METHODS In total,102 patients with HTG-AP were retrospectively enrolled.Demographic and clinical data,including RDW,were collected from all patients on admission.RESULTS Based on the Revised Atlanta Classification,37(33%)of 102 patients with HTG-AP were diagnosed with POF.On admission,RDW was significantly higher in patients with HTG-AP and POF than in those without POF(14.4%vs 12.5%,P<0.001).The receiver operating characteristic curve demonstrated a good discrim-inative power of RDW for POF with a cutoff of 13.1%,where the area under the curve(AUC),sensitivity,and specificity were 0.85,82.4%,and 77.9%,respectively.When the RDW was≥13.1%and one point was added to the original BISAP to obtain a new BISAP score,we achieved a higher AUC,sensitivity,and specificity of 0.89,91.2%,and 67.6%,respectively.CONCLUSION RDW is a promising predictor of POF in patients with HTG-AP,and the addition of RDW can promote the sensitivity of BISAP.展开更多
目的探讨外周血红细胞分布宽度(red blood cell distribution width,RDW)、系统免疫炎症指数(systemic immune-inflammation index,SⅡ)与重性抑郁障碍(major depressive disorder,MDD)的相关性。方法回顾性分析2020-2022年于我院临床...目的探讨外周血红细胞分布宽度(red blood cell distribution width,RDW)、系统免疫炎症指数(systemic immune-inflammation index,SⅡ)与重性抑郁障碍(major depressive disorder,MDD)的相关性。方法回顾性分析2020-2022年于我院临床心理科住院的176例MDD患者和常规体检的209例非MDD对照者的临床资料。从血液分析结果中,得到RDW、SⅡ、红细胞分布宽度与血小板计数比值(RDW to platelet ratio,RPR)。绘制受试者操作特征(receiver operator characteristic,ROC)曲线以确定RDW区分患者与对照的最佳临界值及曲线下面积(area under the curve,AUC)。结果MDD组患者的RDW[中位数及四分位数:13.20(12.70,13.98)vs.12.80(12.40,13.35)]、SⅡ水平[中位数及四分位数:510.87(350.95,878.12)vs.405.33(313.74,539.92)]高于非MDD组对照者,差异有统计学意义(P<0.05),两组间RPR差异无统计学意义(P>0.05)。多因素logistic回归分析结果显示,调整混杂因素后,RDW与MDD呈正关联(OR=3.086,95%CI:1.926~4.944)。ROC曲线结果显示,RDW区分MDD与非MDD的最佳临界值为12.85,AUC为0.647(95%CI:0.592~0.702;P<0.001)。结论高RDW可能是MDD发生的危险因素,是对MDD诊断有价值的重要参数。展开更多
Extreme droughts are anticipated to have detrimental impacts on forest ecosystems,especially in water-limited regions,due to the influence of climate change.However,considerable uncertainty remains regarding the patte...Extreme droughts are anticipated to have detrimental impacts on forest ecosystems,especially in water-limited regions,due to the influence of climate change.However,considerable uncertainty remains regarding the patterns in species-specific responses to extreme droughts.Here,we conducted a study integrating dendrochronology and remote sensing methods to investigate the mosaic-distributed maple-oak(native)natural forests and poplar plantations(introduced)in the Horqin Sandy Land,Northeast China.We assessed the impacts of extreme droughts on tree performances by measuring interannual variations in radial growth and vegetation index.The results showed that precipitation and self-calibrated palmer drought severity index(scPDSI)are the major factors influencing tree-ring width index(RWI)and normalized difference vegetation index(NDVI).The severe droughts between 2000 and 2004 resulted in reduced RWI in the three studied tree species as well as led to NDVI reductions in both the maple-oak natural forests and the poplar plantations.The RWI reached the nadir during the2000-2004 severe droughts and remained at low levels two years after the severe drought,creating a legacy effect.In contrast to the lack of significant correlation between RWI and scPDSI,NDVI exhibited a significant positive correlation with scPDSI indicating the greater sensitivity of canopy performance to droughts than radial growth.Furthermore,interspecific differences in RWI and NDVI responses were observed,with the fast-growing poplar species experiencing a more significant RWI decrease and more negative NDVI anomaly during severe droughts than native species,highlighting the species-specific trade-offs between drought resilience and growth rate.This study emphasizes the importance of combining tree-level radial growth with landscape-scale canopy remote sensing to understand forest resilience and response.Our study improves our understanding of forest responses to extreme drought and highlights species differences in climate responses,offering crucial insights for optimizing species selection in sustainable afforestation and forest management in water-limited regions under the influence of climate change.展开更多
Changes in annual radial growth is an important indication of climate change. Dendroclimatology studies in northern China have focused on linear statistical analysis,but lacking studies based on the process of ring fo...Changes in annual radial growth is an important indication of climate change. Dendroclimatology studies in northern China have focused on linear statistical analysis,but lacking studies based on the process of ring formation to clarify the radial growth of trees. Tree-ring width standard chronology(STD) was established using samples of Larix principis-rupprechtii collected at 2303 m altitude on Luya Mountain. Using the Vaganov-Shashkin(VS) model to simulate growth and development, the internal physiological mechanism of radial growth is identified. It was concluded that:(1) the growing season of L. principis-rupprechtii was May to September;(2) soil moisture was a significant factor in the early and late growing seasons, and temperature was the dominant factor in its main growth period;and(3) formation of narrow ring widths was closely related to drought stress, the development of wide ring widths will be restricted by increasing future temperatures. The VS model is applicable for radial growth simulation of subalpine coniferous forests and for guiding the cultivation of local tree species in the future.展开更多
The choice of extrusion process is a decisive factor that affects the finished product quality for polybag manufacturing. One important component influencing the quality of the finished product is the selection of the...The choice of extrusion process is a decisive factor that affects the finished product quality for polybag manufacturing. One important component influencing the quality of the finished product is the selection of the extrusion technique. Two popular procedures that vary in the kind of dye used and the final product’s texture are cast film and blown film. In the horizontal extrusion moulding method known as “cast film”, heated resin is injected into a flat dye and allowed to cool on chill rolls. The film produced is clear, lightweight, and appropriate for lamination;its thickness varies based on the winding speed and the film is slower to crystallize and has less clarity but more durability because the resin molecules have reoriented, facing limitation of high wastage generation. This study primarily focused on the preparation of polybag film using the blown film extrusion process, utilizing high-quality polymer resins such as polyester polyethylene (PP) and linear low-density polyethylene (LLDPE) to minimize waste generation. The novelty of the process was reflected in minimising the waste generation. The control parameters considered in this study are temperature, pressure, and air intake volume. We investigated the influence of these critical process control parameters on the gauge thickness, optical properties, and mechanical strength of the polybag film produced through blown film extrusion. Additionally, we replicated the blown film process using simulation software developed at Pennsylvania College of Technology. The simulation results confirmed the overall stability of the polybag film produced through the blown film extrusion process.展开更多
基金supported the National Natural Science Foundation of China (42022059,41888101)the Strategic Priority Research Program of the Chinese Academy of Sciences,China (Grant No.XDB26020000)+1 种基金the Key Research Program of the Institute of Geology and Geophysics (CAS Grant IGGCAS-201905)the CAS Youth Interdisciplinary Team (JCTD-2021-05).
文摘Tree-ring width(RW),density,elemental com-position,and stable carbon and oxygen isotope(δ^(13)C,δ^(18)O)are widely used as proxies to assess climate change,ecology,and environmental pollution;however,a specific pretreat-ment has been needed for each proxy.Here,we developed a method by which each proxy can be measured in the same sample.First,the sample is polished for ring width meas-urement.After obtaining the ring width data,the sample is cut to form a 1-mm-thick wood plate.The sample is then mounted in a vertical sample holder,and gradually scanned by an X-ray beam.Simultaneously,the count rates of the fluorescent photons of elements(for chemical characteriza-tion)and a radiographic grayscale image(for wood density)are obtained,i.e.the density and the element content are obtained.Then,cellulose is isolated from the 1-mm wood plate by removal of lignin,and hemicellulose.After producing this cellulose plate,cellulose subsamples are separated by knife under the microscope for inter-annual and intra-annual stable carbon and oxygen isotope(δ^(13)C,δ^(18)O)analysis.Based on this method,RW,density,elemental composition,δ^(13)C,and δ^(18)O can be measured from the same sample,which reduces sample amount and treatment time,and is helpful for multi-proxy comparison and combination research.
基金This work Was supported by the Key Program of the National Natural Science Foundation of China (Grant No. 40331006) the Key Project of Knowledge Innovation of the Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences (Grant No. CXI0G-E01-05 -02).
文摘Using five well-replicated Qilian juniper (Sabina przewalskii Kom.) tree-ring width index se- ries, monthly normalized difference vegetation index (NDVI) of grassland, and climatic data from 1982 to 2001, the relationships between tree-ring width index, NDVI of grassland, and climatic data were analyzed firstly. Then, the relationship between tree-ring width index and NDVI of grassland was explored. The re- sults showed that: (1) Temperature and precipitation in June influenced tree-ring width index and NDVI of grassland deeply in Delingha. (2) There were sig- nificant relationships between five tree-ring width index series (DLH1-DLH5) and monthly NDVI of grassland from June to September, with the most significant relationship being between tree-ring width index series and NDVI of grassland in August. (3) The PC1 (the first principal component derived from DLH1-DLH5 series) exhibited good agreement with monthly NDVI of grassland in the grass growth sea- son (from June to September) and the averaged NDVI in the growth season, which was attributed to their common responses to water-supply limit in Delingha. This study may allow an increase in studying the past dynamics of grassland in Delingha in that the variation of grassland NDVI during the last millennium has been reconstructed from PC1.
基金National Natural Science Foundation of China, No.40525004 No.40599420+2 种基金 No.90211081 No.40531003 No.40121303
文摘Tree-ring standardized chronologies are developed by 78 cores collected from the eastern and western Helan Mountain. Statistical analysis shows that both the STD and RES chronologies correlate negatively with the temperature of different periods of early half year, especially with January to August mean (JA) temperature, which means that JA temperature is one of the predominant limiting factors of tree growth in the Helan Mountain. Based on this analysis, we reconstructed JA temperature, and the explained variance is 43.3% (F=21.422, p〈0.001 ). The comparatively high temperature periods in the reconstruction were: 1805-1818 1828-1857, 1899-1907, 1919-1931 and 1968-1995; and the comparatively low temperatu re periods happened in 1858-1872, 1883-1895 and 1935-1953. Ten-year moving average curve shows three slow uplifting trends: 1766-1853, 1862-1931 and 1944-1995. Each temperature increase was followed by a sudden temperature decrease about 10 years, that is to say, the JA temperature in the Helan Mountain is characterized by slow increase and sudden decrease. The 70- and 10.77-year periodicities detected in the temperature series correspond to the Gleissberg (80-year) and Schwabe (11-year) periodicities of solar activity respectively, the 2.11-2.62 years cycles are considered to be influenced by QBO (Quasi-Biennial-Oscillation) and the local environmental change.
基金supported by the National Natural Science Foundation of China (40801004, 40671184)the Research Fund for the Doctoral Program of Higher Education (20070027019)
文摘Based on the analysis of the correlation between the tree-ring width of Pinus tabulaeformis and the climate factors in the western Hedong sandy land of Ningxia, a conversion equation between the annual precipitation and the tree-ring width since 1899 was reconstructed. The results of cross verification indicated that the conversion equation is stable and the reconstructed results are reliable. The result of reconstructed annual precipitation showed the remarkable fluctuation of precipitation and dry-to-wet variation before the 1940s. The smaller fluctuation and high frequent changes of precipitation occurred during the period of 1940s-1980s and after the 1980s the change trend of the precipitation became high periodic extent and low frequent. The study found that there were some coincidences with the climate change in Changling Mountains, Helan Mountains and the east of Qilian Mountains. The relatively dry periods in the beginning of 20th century, 1920s to 1930s, the end of the 20th century and 2004 to 2006 in the western Hedong sandy land of Ningxia accelerated the desertification, while the relatively humid period during the periods of the 1910s-1920s, 1930s-1940s and 1990s is favorable to prevent and control the desertification, and to weaken the climate warming and drying. The periods of annual precipitation variation in the western Hedong sandy land of Ningxia since 1899 are approximately 2-4 years, 5-7 years and 10 years.
基金funded by the Russian Foundation for Basic Research (17-04-00315)the Russian Science Foundation (14-14-00219)
文摘Regional tree-ring width chronology of the Scots pine (Pinus sylvestris L.) was constructed from 8 sites in the forest-steppe belt situated in the foothills of the Selenga River basin, Russia. Moisture information contained in tree-ring width chronology was obtained through linear regression reconstruction models of annual August–July precipitation and annual water discharge of the Selenga River during the period 1767–2015. Comparison of the smoothed series allowed estimating long-term variation component of these moisture regime parameters with a high precision. At the same time, regional drought indices are less correlated with pine radial growth, because they have contribution of the other environmental variables, which are much less reflected in the tree-ring of the investigated pine forest stands. Reconstructed dynamic of the moisture regime parameters is supported by documental evident of many socially significant events in the regional history, such as crop failures caused by both droughts and floods, and catastrophic fire in the Irkutsk City in 1879. Also, dependence of the amount of precipitation in the study area on the atmospheric circulation in Central Asia is revealed to have a similar pattern with other regions, i.e., a negative relationship of precipitation with the development of large high atmospheric pressure area within its center in the Altai and Tianshan mountains.
基金supported by the Climate Change Special Project of China Meteorological Administration (CCSF201438)the Meteorology Public Welfare Industry Research Special Project (GYHY201106013-3 and GYHY200806011)the Basic Research Operating Expenses of the Central-level Public Welfare Research Institutes (IDM201204)
文摘August-June precipitation has been reconstructed back to AD 1720 for the northern Greater Higgnan Mountains, China, by use ofPinus sylvestris var. mongolica tree-ring width. The reconstruction explains the variance of 39% in observed precipitation from 1973 to 2008. Some extremely dry/wet signals in historical documents and other precipitation reconstructions in previous studies are precisely captured in our reconstruction. Wet periods occurred during the periods of 1730 to 1746, 1789 to 1812, 1844 to 1903, 1920 to 1930, 1942 to 1961, and 1985 to 1998; while periods of 1747 to 1788, 1813 to 1843, 1904 to 1919, 1931 to 1941, and 1962 to 1984 were relatively dry. Power spectral and wavelet analyses demon- strated the existence of significant 24-year, 12-year, and 2-year cycles of variability.
基金supported by the National Natural Science Foundation of China (41275120, 41605047)the Shanghai Cooperation Organization Science and Technology Partnership (2017E01032)+1 种基金the Special Foundation for Asian Regional Cooperation (Climate Reconstruction of Tian Shan in China, Kyrgyzstan and Tajikistan)the Autonomous Region Youth Science and Technology Innovation Talents Training Project (qn2015bs025)
文摘Reconstructing the hydrological change based on dendrohydrological data has important implications for understanding the dynamic distribution and evolution pattern of a given river. The widespread, long-living coniferous forests on the Altay Mountains provide a good example for carrying out the dendrohydrological studies. In this study, a regional composite tree-ring width chronology developed by Lariat sibirica Ledeb. and Picea obovata Ledeb. was used to reconstruct a 301-year annual (from preceding July to succeeding June) streamflow for the Haba River, which originates in the southern Altay Mountains, Xinjiang, China. Results indicated that the reconstructed streamflow series and the observations were fitting well, and explained 47.5% of the variation in the observed streamflow of 1957-2008. Moreover, floods and droughts in 1949-2000 were precisely captured by the streamflow reconstruction. Based on the frequencies of the wettest/driest years and decades, we identified the 19th century as the century with the largest occurrence of hydrological fluctuations for the last 300 years. After applying a 21-year moving average, we found five wet (1724-1758, 1780-1810, 1822-1853, 1931-1967, and 1986-2004) and four dry (1759-1779, 1811-1821, 1854-1930, and 1968-1985) periods in the streamflow reconstruction. Furthermore, four periods (1770-1796, 1816-1836, 1884-1949, and 1973-1997) identified by the streamflow series had an obvious increasing trend. The increasing trend of streamflow since the 1970s was the biggest in the last 300 years and coincided with the recent warming-wetting trend in northwestern China. A significant correlation between streamflow and precipitation in the Altay Mountains indicated that the streamflow reconstruction contained not only local, but also broad-scale, hydro-climatic signals. The 24-year, 12-year, and 2.2-4.5-year cycles of the reconstruction revealed that the streamflow variability of the Haba River may be influenced by solar activity and the atmosphere-ocean system.
基金funded by National Natural Science Foundation of China(No.31370587)
文摘Tree-ring width chronologies of Larix chinensis were developed from the northern and southern slopes of the Qinling Mountains in Shaanxi Province,and climatic factors affecting the tree-ring widths of L.chinensis were examined.Correlation analysis showed that similar correlations between tree-ring width chronologies and climatic factors demonstrated that radial growth responded to climate change on both slopes.The radial growth of L.chinensis was mainly limited by temperature,especially the growing season.In contrast,both chronologies were negatively correlated with precipitation in May of the previous year and April of the current year.Spatial climate-correlation analyses with gridded land-surface climate data revealed that our tree-ring width chronologies contained a strong regional temperature signal over much of northcentral and eastern China.Spatial correlation with seasurface temperature fields highlights the influence of the Pacific Ocean,Indian Ocean,and North Atlantic Ocean.Wavelet coherence analysis indicated the existence of some decadal and interannual cycles in the two tree-ring width chronologies.This may suggest the influences of El Nin˜o-Southern Oscillation and solar activity on tree growth in the Qinling Mountains.These findings will help us understand the growth response of L.chinensis to climate change in the Qinling region,and they provide critical information for future climate reconstructions based on this species in semi-humid regions.
基金the Science and Technology Program of Guiyang Baiyun District Science and Technology Bureau.No.[2017]50Science and Technology Program of Guiyang Municipal Bureau of Science and Technology,No.[2018]1-72Science and Technology Fund Project of Guizhou Provincial Health Commission,No.gzwkj2021-127.
文摘BACKGROUND Compared with patients with other causes of acute pancreatitis,those with hypertriglyceridemia-induced acute pancreatitis(HTG-AP)are more likely to develop persistent organ failure(POF).Therefore,recognizing the individuals at risk of developing POF early in the HTG-AP process is a vital for improving outcomes.Bedside index for severity in acute pancreatitis(BISAP),a simple parameter that is obtained 24 h after admission,is an ideal index to predict HTG-AP severity;however,the suboptimal sensitivity limits its clinical application.Hence,current clinical scoring systems and biochemical parameters are not sufficient for predicting HTG-AP severity.AIM To elucidate the early predictive value of red cell distribution width(RDW)for POF in HTG-AP.METHODS In total,102 patients with HTG-AP were retrospectively enrolled.Demographic and clinical data,including RDW,were collected from all patients on admission.RESULTS Based on the Revised Atlanta Classification,37(33%)of 102 patients with HTG-AP were diagnosed with POF.On admission,RDW was significantly higher in patients with HTG-AP and POF than in those without POF(14.4%vs 12.5%,P<0.001).The receiver operating characteristic curve demonstrated a good discrim-inative power of RDW for POF with a cutoff of 13.1%,where the area under the curve(AUC),sensitivity,and specificity were 0.85,82.4%,and 77.9%,respectively.When the RDW was≥13.1%and one point was added to the original BISAP to obtain a new BISAP score,we achieved a higher AUC,sensitivity,and specificity of 0.89,91.2%,and 67.6%,respectively.CONCLUSION RDW is a promising predictor of POF in patients with HTG-AP,and the addition of RDW can promote the sensitivity of BISAP.
文摘目的研究术前血小板分布宽度(Platelet volume distribution width,PDW)联合系统性炎症指数(Systemic inflammation response index,SIRI)对结肠癌术后复发转移的预测价值。方法以2020年1月-2021年6月江苏大学附属医院胃肠外科就诊并接受根治性切除手术治疗的194例结肠癌患者为结肠癌组,选择同期在本院体检中心招募的100例健康体检者为对照组。术前检测并记录PDW和SIRI,收集患者的一般资料包括:性别、年龄、身高、体重、家族肿瘤史、是否吸烟、酗酒、体质指数(Body mass index,BMI)、肿瘤最大径、TNM分期(Tumor node metastasis,TNM)和分化程度。对患者随访2年,记录结肠癌复发转移情况。采用ROC曲线确定相关变量的临界最佳值,通过AUC(ROC曲线下面积)评价其预后的准确性。结果与对照组比较,结肠癌组PDW和SIRI均显著增高,差异有统计学意义(P<0.05)。术后发生复发转移患者术前PDW与SIRI高于术后未发生复发转移的患者,差异有统计学意义(P<0.05)。TNM分期Ⅲ~Ⅳ期和中低分化程度术后复发转移患者的PDW高于Ⅰ~Ⅱ期患者和高分化程度患者,差异有统计学意义(P<0.05)。肿瘤最大径≥5 cm、TNM分期Ⅲ~Ⅳ期和中低分化程度术后复发转移患者的PDW高于肿瘤最大径<5 cm、TNM分期Ⅰ~Ⅱ期和高分化程度的患者,差异有统计学意义(P<0.05)。PDW、SIRI及两者联合预测结肠癌术后复发转移的曲线下面积(Area under curve,AUC)分别为0.761(95%CI:0.691~0.831),0.836(95%CI:0.775~0.897)和0.918(95%CI:0.876~0.960)。术后复发转移患者的PDW与SIRI呈显著正相关关系(r=0.574,P=0.003)。结论PDW、SIRI与结肠癌患者临床病理特征和术后复发转移有关,两者联合预测术后复发转移的效能较好,可为临床应用提供一定参考价值。
文摘目的探讨外周血红细胞分布宽度(red blood cell distribution width,RDW)、系统免疫炎症指数(systemic immune-inflammation index,SⅡ)与重性抑郁障碍(major depressive disorder,MDD)的相关性。方法回顾性分析2020-2022年于我院临床心理科住院的176例MDD患者和常规体检的209例非MDD对照者的临床资料。从血液分析结果中,得到RDW、SⅡ、红细胞分布宽度与血小板计数比值(RDW to platelet ratio,RPR)。绘制受试者操作特征(receiver operator characteristic,ROC)曲线以确定RDW区分患者与对照的最佳临界值及曲线下面积(area under the curve,AUC)。结果MDD组患者的RDW[中位数及四分位数:13.20(12.70,13.98)vs.12.80(12.40,13.35)]、SⅡ水平[中位数及四分位数:510.87(350.95,878.12)vs.405.33(313.74,539.92)]高于非MDD组对照者,差异有统计学意义(P<0.05),两组间RPR差异无统计学意义(P>0.05)。多因素logistic回归分析结果显示,调整混杂因素后,RDW与MDD呈正关联(OR=3.086,95%CI:1.926~4.944)。ROC曲线结果显示,RDW区分MDD与非MDD的最佳临界值为12.85,AUC为0.647(95%CI:0.592~0.702;P<0.001)。结论高RDW可能是MDD发生的危险因素,是对MDD诊断有价值的重要参数。
基金supported by the National Natural Science Foundation of China(Nos.32220103010,32192431,31722013)the National Key R&D Program of China(Nos.2023YFF1304201,2020YFA0608100)+1 种基金the Major Program of Institute of Applied EcologyChinese Academy of Sciences(No.IAEMP202201)。
文摘Extreme droughts are anticipated to have detrimental impacts on forest ecosystems,especially in water-limited regions,due to the influence of climate change.However,considerable uncertainty remains regarding the patterns in species-specific responses to extreme droughts.Here,we conducted a study integrating dendrochronology and remote sensing methods to investigate the mosaic-distributed maple-oak(native)natural forests and poplar plantations(introduced)in the Horqin Sandy Land,Northeast China.We assessed the impacts of extreme droughts on tree performances by measuring interannual variations in radial growth and vegetation index.The results showed that precipitation and self-calibrated palmer drought severity index(scPDSI)are the major factors influencing tree-ring width index(RWI)and normalized difference vegetation index(NDVI).The severe droughts between 2000 and 2004 resulted in reduced RWI in the three studied tree species as well as led to NDVI reductions in both the maple-oak natural forests and the poplar plantations.The RWI reached the nadir during the2000-2004 severe droughts and remained at low levels two years after the severe drought,creating a legacy effect.In contrast to the lack of significant correlation between RWI and scPDSI,NDVI exhibited a significant positive correlation with scPDSI indicating the greater sensitivity of canopy performance to droughts than radial growth.Furthermore,interspecific differences in RWI and NDVI responses were observed,with the fast-growing poplar species experiencing a more significant RWI decrease and more negative NDVI anomaly during severe droughts than native species,highlighting the species-specific trade-offs between drought resilience and growth rate.This study emphasizes the importance of combining tree-level radial growth with landscape-scale canopy remote sensing to understand forest resilience and response.Our study improves our understanding of forest responses to extreme drought and highlights species differences in climate responses,offering crucial insights for optimizing species selection in sustainable afforestation and forest management in water-limited regions under the influence of climate change.
基金supported by Alpine timberline fluctuations and the response to climate change at centennial to millennial time scales in the Qinling Mountains (no.42371072)a General Programfrom the Natural Science Foundation of Shaanxi Province (no.2014JQ5172)+1 种基金the Open Fund Project of the State Key Laboratory of Loess and Quaternary Geology (no.SKLLQG1611)the National Forestry Public Welfare Industry Scientific Research Project of China (no.201304309).
文摘Changes in annual radial growth is an important indication of climate change. Dendroclimatology studies in northern China have focused on linear statistical analysis,but lacking studies based on the process of ring formation to clarify the radial growth of trees. Tree-ring width standard chronology(STD) was established using samples of Larix principis-rupprechtii collected at 2303 m altitude on Luya Mountain. Using the Vaganov-Shashkin(VS) model to simulate growth and development, the internal physiological mechanism of radial growth is identified. It was concluded that:(1) the growing season of L. principis-rupprechtii was May to September;(2) soil moisture was a significant factor in the early and late growing seasons, and temperature was the dominant factor in its main growth period;and(3) formation of narrow ring widths was closely related to drought stress, the development of wide ring widths will be restricted by increasing future temperatures. The VS model is applicable for radial growth simulation of subalpine coniferous forests and for guiding the cultivation of local tree species in the future.
文摘The choice of extrusion process is a decisive factor that affects the finished product quality for polybag manufacturing. One important component influencing the quality of the finished product is the selection of the extrusion technique. Two popular procedures that vary in the kind of dye used and the final product’s texture are cast film and blown film. In the horizontal extrusion moulding method known as “cast film”, heated resin is injected into a flat dye and allowed to cool on chill rolls. The film produced is clear, lightweight, and appropriate for lamination;its thickness varies based on the winding speed and the film is slower to crystallize and has less clarity but more durability because the resin molecules have reoriented, facing limitation of high wastage generation. This study primarily focused on the preparation of polybag film using the blown film extrusion process, utilizing high-quality polymer resins such as polyester polyethylene (PP) and linear low-density polyethylene (LLDPE) to minimize waste generation. The novelty of the process was reflected in minimising the waste generation. The control parameters considered in this study are temperature, pressure, and air intake volume. We investigated the influence of these critical process control parameters on the gauge thickness, optical properties, and mechanical strength of the polybag film produced through blown film extrusion. Additionally, we replicated the blown film process using simulation software developed at Pennsylvania College of Technology. The simulation results confirmed the overall stability of the polybag film produced through the blown film extrusion process.