Sea ice is a crucial component of the ocean-atmosphere interaction system,particularly Antarctic sea ice,which significantly impacts global climate change.This study analyzes the spatiotemporal variation characteristi...Sea ice is a crucial component of the ocean-atmosphere interaction system,particularly Antarctic sea ice,which significantly impacts global climate change.This study analyzes the spatiotemporal variation characteristics of sea ice extent in Antarctica and its surrounding five sub-regions(Weddell Sea,Indian Ocean,Pacific Ocean,Ross Sea,and Bellingshausen-Amundsen Sea)from 1979 to 2022.Using the time series analysis method of Fourier series expansion,we explore the characteristics and trends of Antarctic sea ice extent changes from two perspectives:periodic fluctuations and trend stability.Our results indicate that:(1)The seasonal variation characteristics of Antarctic sea ice extent are pronounced,with the smallest extent in summer(February)and the largest in winter(September).From 1979 to 2022,the overall trend of changes in Antarctic sea ice extent was not significant,but the periodic characteristics were distinct.During this period,there were several abrupt decreases in sea ice extent,and the extent of Antarctic sea ice in 2022 was the smallest since satellite observations began.From 1980 to 2009,the extent of Antarctic sea ice increased stepwise on an interdecadal scale,while from 2010 to 2022,it decreased.(2)There is one smooth structural break in the sea ice extent of each sub-region of Antarctica.There are three smooth structural breaks in the Antarctic sea ice extent,and the variation differences in the sea ice extent of the surrounding areas contribute to more frequent changes in the overall Antarctic sea ice extent.(3)The changes in Antarctic sea ice are influenced by many factors,and in the future,it is necessary to strengthen observation and simulation to provide a scientific basis for climate change research.展开更多
Latitudinal patterns of treeβ-diversity reveal important insights into the biogeographical processes that influence forest ecosystems.Although previous studies have extensively documentedβ-diversity within relativel...Latitudinal patterns of treeβ-diversity reveal important insights into the biogeographical processes that influence forest ecosystems.Although previous studies have extensively documentedβ-diversity within relatively small spatial extents,the potential drivers ofβ-diversity along latitudinal gradients are still not well understood at larger spatial extents.In this study,we determined whether treeβ-diversity is correlated with latitude in forests of southeastern China,and if so,what ecological processes contribute to these patterns of treeβ-diversity.We specifically aimed to disentangle the relative contributions from interspecific aggregation and environmental filtering across various spatial extents.We delineated regional communities comprising multiple nearby national forest inventory(NFI)plots around random focal plots.The number of NFI plots in a regional community served as a surrogate for spatial extent.We also used a null model to simulate randomly assembled communities and quantify the deviation(β-deviation)between observed and expectedβ-diversity.We found thatβ-diversity decreased along a latitudinal gradient and that this pattern was clearer at larger spatial extents.In addition,latitudinal patterns ofβ-deviation were explained by the degree of species spatial aggregation.We also identified environmental factors that driveβ-deviation in these forests,including precipitation,seasonality,and temperature variation.At larger spatial extents,these environmental variables explained up to 84%of theβ-deviation.Our results reinforce that ecological processes are scale-dependent and collectively contribute to theβ-gradient in subtropical forests.We recommend that conservation efforts maintain diverse forests and heterogeneous environments at multiple spatial extents to mitigate the adverse effects of climate change.展开更多
BACKGROUND Understanding the type and extent of coronary artery involvement in patients with acute type A aortic dissection(ATAAD)is vital for surgical planning.The Neri classification has been proposed as a guide for...BACKGROUND Understanding the type and extent of coronary artery involvement in patients with acute type A aortic dissection(ATAAD)is vital for surgical planning.The Neri classification has been proposed as a guide for surgical strategies,however,its prognostic impact on postoperative mortality rates remains understudied in large-scale cohorts.METHODS We reviewed 600 ATAAD patients who underwent surgery and coronary computed tomography angiography from 2016 to 2020 at Fuwai Hospital,National Center for Cardiovascular Diseases,Chinese Academy of Medical Sciences and Peking Union Medical College,Beijing,China.Patients were classified based on the Neri classification system:no coronary artery involvement,type A(ostial involvement),type B(dissection in coronary body),and type C(circumferential detachment or complete avulsion).The primary endpoint was 30-day mortality.RESULTS Overall,28.3%of the patients had coronary artery involvement,with Neri type A,Neri type B,and Neri type C accounting for 13.3%,11.2%,and 3.8%,respectively.The right coronary artery was more frequently involved(25.3%)than the left coronary artery(8.0%).In the unadjusted analysis,patients with coronary artery involvement exhibited a numerically higher 30-day mortality compared to those without(5.3%vs.2.3%)(OR=2.35,95%CI:0.94–5.88,P=0.07),though this difference did not reach statistical significance.However,multivariable adjustment revealed significant association(adjusted OR=3.71,95%CI:1.05–13.13,P=0.04).Interestingly,after additional adjustment for coronary artery bypass grafting,the impact of coronary artery involvement on 30-day mortality no longer remained statistically significant(adjusted OR=3.13,95%CI:0.85–11.58,P=0.09).The 1-year mortality was higher in those with coronary artery involvement,but this significant association disappeared after adjusting for potential confounding variables.Furthermore,no significant difference in 30-day and 1-year mortality were observed among patients with different Neri classifications.CONCLUSIONS In patients with ATAAD who undergo surgery,the presence of coronary artery involvement is significantly associated with an increased risk of 30-day mortality.Proactive coronary artery bypass grafting may potentially mitigate the adverse impact of coronary artery involvement on 30-day mortality.展开更多
文摘Sea ice is a crucial component of the ocean-atmosphere interaction system,particularly Antarctic sea ice,which significantly impacts global climate change.This study analyzes the spatiotemporal variation characteristics of sea ice extent in Antarctica and its surrounding five sub-regions(Weddell Sea,Indian Ocean,Pacific Ocean,Ross Sea,and Bellingshausen-Amundsen Sea)from 1979 to 2022.Using the time series analysis method of Fourier series expansion,we explore the characteristics and trends of Antarctic sea ice extent changes from two perspectives:periodic fluctuations and trend stability.Our results indicate that:(1)The seasonal variation characteristics of Antarctic sea ice extent are pronounced,with the smallest extent in summer(February)and the largest in winter(September).From 1979 to 2022,the overall trend of changes in Antarctic sea ice extent was not significant,but the periodic characteristics were distinct.During this period,there were several abrupt decreases in sea ice extent,and the extent of Antarctic sea ice in 2022 was the smallest since satellite observations began.From 1980 to 2009,the extent of Antarctic sea ice increased stepwise on an interdecadal scale,while from 2010 to 2022,it decreased.(2)There is one smooth structural break in the sea ice extent of each sub-region of Antarctica.There are three smooth structural breaks in the Antarctic sea ice extent,and the variation differences in the sea ice extent of the surrounding areas contribute to more frequent changes in the overall Antarctic sea ice extent.(3)The changes in Antarctic sea ice are influenced by many factors,and in the future,it is necessary to strengthen observation and simulation to provide a scientific basis for climate change research.
基金supported by the National Natural Science Foundation of China(42271317)the Innovation Research Team Project of the Natural Science Foundation of Hainan Province(422CXTD515)。
文摘Latitudinal patterns of treeβ-diversity reveal important insights into the biogeographical processes that influence forest ecosystems.Although previous studies have extensively documentedβ-diversity within relatively small spatial extents,the potential drivers ofβ-diversity along latitudinal gradients are still not well understood at larger spatial extents.In this study,we determined whether treeβ-diversity is correlated with latitude in forests of southeastern China,and if so,what ecological processes contribute to these patterns of treeβ-diversity.We specifically aimed to disentangle the relative contributions from interspecific aggregation and environmental filtering across various spatial extents.We delineated regional communities comprising multiple nearby national forest inventory(NFI)plots around random focal plots.The number of NFI plots in a regional community served as a surrogate for spatial extent.We also used a null model to simulate randomly assembled communities and quantify the deviation(β-deviation)between observed and expectedβ-diversity.We found thatβ-diversity decreased along a latitudinal gradient and that this pattern was clearer at larger spatial extents.In addition,latitudinal patterns ofβ-deviation were explained by the degree of species spatial aggregation.We also identified environmental factors that driveβ-deviation in these forests,including precipitation,seasonality,and temperature variation.At larger spatial extents,these environmental variables explained up to 84%of theβ-deviation.Our results reinforce that ecological processes are scale-dependent and collectively contribute to theβ-gradient in subtropical forests.We recommend that conservation efforts maintain diverse forests and heterogeneous environments at multiple spatial extents to mitigate the adverse effects of climate change.
基金supported by the National High Level Hospital Clinical Research Funding(No.2024-GSP-TJ-15&No.2023-GSP-QN-17)the Chinese Society of Cardiology’s Foundation(CSCF2023B03).
文摘BACKGROUND Understanding the type and extent of coronary artery involvement in patients with acute type A aortic dissection(ATAAD)is vital for surgical planning.The Neri classification has been proposed as a guide for surgical strategies,however,its prognostic impact on postoperative mortality rates remains understudied in large-scale cohorts.METHODS We reviewed 600 ATAAD patients who underwent surgery and coronary computed tomography angiography from 2016 to 2020 at Fuwai Hospital,National Center for Cardiovascular Diseases,Chinese Academy of Medical Sciences and Peking Union Medical College,Beijing,China.Patients were classified based on the Neri classification system:no coronary artery involvement,type A(ostial involvement),type B(dissection in coronary body),and type C(circumferential detachment or complete avulsion).The primary endpoint was 30-day mortality.RESULTS Overall,28.3%of the patients had coronary artery involvement,with Neri type A,Neri type B,and Neri type C accounting for 13.3%,11.2%,and 3.8%,respectively.The right coronary artery was more frequently involved(25.3%)than the left coronary artery(8.0%).In the unadjusted analysis,patients with coronary artery involvement exhibited a numerically higher 30-day mortality compared to those without(5.3%vs.2.3%)(OR=2.35,95%CI:0.94–5.88,P=0.07),though this difference did not reach statistical significance.However,multivariable adjustment revealed significant association(adjusted OR=3.71,95%CI:1.05–13.13,P=0.04).Interestingly,after additional adjustment for coronary artery bypass grafting,the impact of coronary artery involvement on 30-day mortality no longer remained statistically significant(adjusted OR=3.13,95%CI:0.85–11.58,P=0.09).The 1-year mortality was higher in those with coronary artery involvement,but this significant association disappeared after adjusting for potential confounding variables.Furthermore,no significant difference in 30-day and 1-year mortality were observed among patients with different Neri classifications.CONCLUSIONS In patients with ATAAD who undergo surgery,the presence of coronary artery involvement is significantly associated with an increased risk of 30-day mortality.Proactive coronary artery bypass grafting may potentially mitigate the adverse impact of coronary artery involvement on 30-day mortality.
