Air quality in eastern China has becoming more and more worrying in recent years, and haze is now No.1 air pollution issue. Results in this study show the decreasing Arctic sea ice(ASI) is an important contributor to ...Air quality in eastern China has becoming more and more worrying in recent years, and haze is now No.1 air pollution issue. Results in this study show the decreasing Arctic sea ice(ASI) is an important contributor to the recent increased haze days in eastern China. The authors find that the number of winter haze days(WHD) in eastern China is strongly negatively correlated with the preceding autumn ASI during 1979–2012, and about 45%– 67% of the WHD interannual to interdecadal variability can be explained by ASI variability. Following previous studies on the impact of ASI loss on the northern hemisphere climate, the authors' studies further reveal that the reduction of autumn ASI leads to positive sea-level pressure anomalies in mid-latitude Eurasia, northward shift of track of cyclone activity in China, and weak Rossby wave activity in eastern China south of 40N during winter season. These atmospheric circulation changes favor less cyclone activity and more stable atmosphere in eastern China, leading to more haze days there. Furthermore, the patterns of circulation changes associated with autumn ASI and WHD are in very good agreement over the East Asia, particularly in eastern China. The authors suggest that haze pollution may continue to be a serious issue in the near future as the decline of ASI continues under global warming.展开更多
By using the radiosonde measurements collected at Shouxian,China,we examined the dynamics and thermodynamics of single- and two-layer clouds formed at low and middle levels.The analyses indicated that the horizontal w...By using the radiosonde measurements collected at Shouxian,China,we examined the dynamics and thermodynamics of single- and two-layer clouds formed at low and middle levels.The analyses indicated that the horizontal wind speed above the cloud layers was higher than those within and below cloud layers.The maximum balloon ascent speed(5.3 m s^(-1)) was located in the vicinity of the layer with the maximum cloud occurrence frequency(24.4%),indicating an upward motion(0.1-0.16 ms^(-1)).The average thickness,magnitude and gradient of the temperature inversion layer above single-layer clouds were117±94 m,1.3±1.3℃ and 1.4±1.5℃(100 m)^(-1),respectively.The average temperature inversion magnitude was the same(1.3℃) for single-low and single-middle clouds;however,a larger gradient[1.7±1.8℃(100 m)^(-1)]and smaller thickness(94±67 m) were detected above single-low clouds relative to those above single-middle clouds[0.9±0.7℃(100 m)^(-1) and157±120 m].For the two-layer cloud,the temperature inversion parameters were 106±59 m,1.0±0.9℃ and 1.0±1.0℃(100 m)^(-1) above the upper-layer cloud and 82 ± 60 m,0.6±0.9℃ and 0.7±0.6℃(100 m)^(-1) above the low-layer cloud.Absolute differences between the cloud-base height(cloud-top height) and the lifting condensation level(equilibrium level)were less than 0.5 km for 66.4%(36.8%) of the cases analyzed in summer.展开更多
Recent studies demonstrate that the Antarctic Ozone Hole has important influences on Antarctic sea ice.While most of these works have focused on effects associated with atmospheric and oceanic dynamic processes caused...Recent studies demonstrate that the Antarctic Ozone Hole has important influences on Antarctic sea ice.While most of these works have focused on effects associated with atmospheric and oceanic dynamic processes caused by stratospheric ozone changes,here we show that stratospheric ozone-induced cloud radiative effects also play important roles in causing changes in Antarctic sea ice.Our simulations demonstrate that the recovery of the Antarctic Ozone Hole causes decreases in clouds over Southern Hemisphere(SH)high latitudes and increases in clouds over the SH extratropics.The decrease in clouds leads to a reduction in downward infrared radiation,especially in austral autumn.This results in cooling of the Southern Ocean surface and increasing Antarctic sea ice.Surface cooling also involves ice-albedo feedback.Increasing sea ice reflects solar radiation and causes further cooling and more increases in Antarctic sea ice.展开更多
Dominant statistical patterns of winter Arctic surface wind(WASW) variability and their impacts on Arctic sea ice motion are investigated using the complex vector empirical orthogonal function(CVEOF) method. The resul...Dominant statistical patterns of winter Arctic surface wind(WASW) variability and their impacts on Arctic sea ice motion are investigated using the complex vector empirical orthogonal function(CVEOF) method. The results indicate that the leading CVEOF of Arctic surface wind variability, which accounts for 33% of the covariance, is characterized by two different and alternating spatial patterns(WASWP1 and WASWP2). Both WASWP1 and WASWP2 show strong interannual and decadal variations, superposed on their declining trends over past decades. Atmospheric circulation anomalies associated with WASWP1 and WASWP2 exhibit, respectively, equivalent barotropic and some baroclinic characteristics, differing from the Arctic dipole anomaly and the seesaw structure anomaly between the Barents Sea and the Beaufort Sea. On decadal time scales, the decline trend of WASWP2 can be attributed to persistent warming of sea surface temperature in the Greenland—Barents—Kara seas from autumn to winter, reflecting the effect of the Arctic warming. The second CVEOF, which accounts for 18% of the covariance, also contains two different spatial patterns(WASWP3 and WASWP4). Their time evolutions are significantly correlated with the North Atlantic Oscillation(NAO) index and the central Arctic Pattern, respectively, measured by the leading EOF of winter sea level pressure(SLP) north of 70°N. Thus, winter anomalous surface wind pattern associated with the NAO is not the most important surface wind pattern. WASWP3 and WASWP4 primarily reflect natural variability of winter surface wind and neither exhibits an apparent trend that differs from WASWP1 or WASWP2. These dominant surface wind patterns strongly influence Arctic sea ice motion and sea ice exchange between the western and eastern Arctic. Furthermore, the Fram Strait sea ice volume flux is only significantly correlated with WASWP3. The results demonstrate that surface and geostrophic winds are not interchangeable in terms of describing wind field variability over the Arctic Ocean. The results have important implications for understanding and investigating Arctic sea ice variations: Dominant patterns of Arctic surface wind variability, rather than simply whether there are the Arctic dipole anomaly and the Arctic Oscillation(or NAO), effectively affect the spatial distribution of Arctic sea ice anomalies.展开更多
Many flaviviruses are emerging and reemerging pathogens,such as West Nile virus(WNV) ,dengue virus(DENV) ,yellow fever virus(YFV) ,and Japanese encephalitis virus. Serological assay is the dominant method for diagnosi...Many flaviviruses are emerging and reemerging pathogens,such as West Nile virus(WNV) ,dengue virus(DENV) ,yellow fever virus(YFV) ,and Japanese encephalitis virus. Serological assay is the dominant method for diagnosis of flavivirus infections in human. Because antibodies generated during flavivirus infections cross-react with other flavivirus members,plaque reduction neutralization test(PRNT) is the only available assay to determine the infecting flavivirus type. Since PRNT requires culturing raw viruses,it must be performed in biosafety level-3 or level-4 containment for many flaviviruses,and takes more than ten days to complete. To overcome these problems,we have developed flavivirus viral-like particles(VLPs) that could be used to replace raw viruses in the neutralization assay. The VLPs were prepared by trans packaging a luciferase-reporting replicon with viral structural proteins. This novel assay involves three simple steps:(i) VLPs from a panel of flaviviruses are incubated with flavivirus-infected sera at 37℃ for 1 h;(ii) the neutralized VLPs are used to infect Vero cells;and(iii) the infected cells are measured for luciferase activities at 22 h post-infection. The virus type whose VLP is most efficiently neutralized by the serum specimen(as quantified by the luciferase activities) is the etiologic agent. As a proof-of-concept,we show that a WNV-infected mouse serum neutralized the WNV VLP more efficiently and selectively than the DENV and YFV VLPs. Our results demonstrate that the VLP neutralization assay maintains the "gold standard" of the classic PRNT;importantly,it shortens the assay time from >10 days to <1 day,and can be performed in biosafety level-2 facility.展开更多
Determining the species of origin of skeletal remains is critical in a forensic and anthropologic context. However, there are very few methods that use a chemical approach to assist in this determination. In this stud...Determining the species of origin of skeletal remains is critical in a forensic and anthropologic context. However, there are very few methods that use a chemical approach to assist in this determination. In this study, Raman spectroscopy was used to discriminate bone samples originating from four different species (bovine, porcine, turkey and chicken). Spectra were obtained using a near infrared laser at 785-nm. All spectra were combined in a single matrix and processed using partial least squares discriminate analysis (PLS-DA) with leave-one-out cross-validation. Three com-ponents were found to adequately describe the system. The first two components which contributed over 85% of spec-tral data was seen to completely separate the four species of origin in a two dimensional scores plot. A 95% confidence interval was draw around score points of each species class with very slight overlap. The first two components were seen to have large contributions from bioapatite and collagen, the main components of bone. This study serves as a preliminary investigation to evaluate the effectiveness of Raman spectroscopy to discriminate the species of origin of bone tissue.展开更多
OBJECTIVE Hybrid coronary revascularization(HCR)combines a minimally invasive surgical approach to the left anterior descending(LAD)artery with percutaneous coronary intervention(PCI)for non-LAD diseased coronary arte...OBJECTIVE Hybrid coronary revascularization(HCR)combines a minimally invasive surgical approach to the left anterior descending(LAD)artery with percutaneous coronary intervention(PCI)for non-LAD diseased coronary arteries.It is associated with shorter hospital lengths of stay and recovery times than conventional coronary artery bypass surgery,but there is little information comparing it to isolated PCI for multivessel disease.Our objective is to compare long-term outcomes of HCR and PCI for patients with multivessel disease.METHODS This cohort study used data from New York’s cardiac surgery and PCI registries in 2010−2016 to examine mortality and repeat revascularization rates for patients with multivessel coronary artery disease who underwent HCR and PCI.Cox proportional hazards methods were used to reduce selection bias.Patients were followed for a median of four years.RESULTS There was a total of 335 HCR patients(1.2%)and 25,557 PCI patients(98.8%)after exclusions.There was no difference in 6-year risk adjusted survival between HCR and PCI patients 83.17%vs.81.65%,adjusted hazard ratio(aHR)=0.90(95%CI:0.67−1.20).However,HCR patients were more likely to be free from repeat revascularization in the LAD artery(91.13%vs.83.59%,aHR=0.51(95%CI:0.34−0.77)).CONCLUSIONS For patients with multi-vessel coronary artery disease,HCR is rarely performed.There are no differences in mortality rates after four years,but HCR is associated with lower repeat revascularization rates in the LAD artery,presumably due to better longevity in left arterial mammary grafts.展开更多
Seasonal minimum Antarctic sea ice extent(SIE)in 2022 hit a new record low since recordkeeping began in 1978 of 1.9 million km^(2) on 25 February,0.17 million km^(2) lower than the previous record low set in 2017.Sign...Seasonal minimum Antarctic sea ice extent(SIE)in 2022 hit a new record low since recordkeeping began in 1978 of 1.9 million km^(2) on 25 February,0.17 million km^(2) lower than the previous record low set in 2017.Significant negative anomalies in the Bellingshausen/Amundsen Seas,the Weddell Sea,and the western Indian Ocean sector led to the new record minimum.The sea ice budget analysis presented here shows that thermodynamic processes dominate sea ice loss in summer through enhanced poleward heat transport and albedo-temperature feedback.In spring,both dynamic and thermodynamic processes contribute to negative sea ice anomalies.Specifically,dynamic ice loss dominates in the Amundsen Sea as evidenced by sea ice thickness(SIT)change,while positive surface heat fluxes contribute most to sea ice melt in the Weddell Sea.展开更多
Several consecutive extreme cold events impacted China during the first half of winter 2020/21,breaking the low-temperature records in many cities.How to make accurate climate predictions of extreme cold events is sti...Several consecutive extreme cold events impacted China during the first half of winter 2020/21,breaking the low-temperature records in many cities.How to make accurate climate predictions of extreme cold events is still an urgent issue.The synergistic effect of the warm Arctic and cold tropical Pacific has been demonstrated to intensify the intrusions of cold air from polar regions into middle-high latitudes,further influencing the cold conditions in China.However,climate models failed to predict these two ocean environments at expected lead times.Most seasonal climate forecasts only predicted the 2020/21 La Niña after the signal had already become apparent and significantly underestimated the observed Arctic sea ice loss in autumn 2020 with a 1-2 month advancement.In this work,the corresponding physical factors that may help improve the accuracy of seasonal climate predictions are further explored.For the 2020/21 La Niña prediction,through sensitivity experiments involving different atmospheric-oceanic initial conditions,the predominant southeasterly wind anomalies over the equatorial Pacific in spring of 2020 are diagnosed to play an irreplaceable role in triggering this cold event.A reasonable inclusion of atmospheric surface winds into the initialization will help the model predict La Niña development from the early spring of 2020.For predicting the Arctic sea ice loss in autumn 2020,an anomalously cyclonic circulation from the central Arctic Ocean predicted by the model,which swept abnormally hot air over Siberia into the Arctic Ocean,is recognized as an important contributor to successfully predicting the minimum Arctic sea ice extent.展开更多
To improve the Arctic sea ice forecast skill of the First Institute of Oceanography-Earth System Model(FIO-ESM)climate forecast system,satellite-derived sea ice concentration and sea ice thickness from the Pan-Arctic ...To improve the Arctic sea ice forecast skill of the First Institute of Oceanography-Earth System Model(FIO-ESM)climate forecast system,satellite-derived sea ice concentration and sea ice thickness from the Pan-Arctic IceOcean Modeling and Assimilation System(PIOMAS)are assimilated into this system,using the method of localized error subspace transform ensemble Kalman filter(LESTKF).Five-year(2014–2018)Arctic sea ice assimilation experiments and a 2-month near-real-time forecast in August 2018 were conducted to study the roles of ice data assimilation.Assimilation experiment results show that ice concentration assimilation can help to get better modeled ice concentration and ice extent.All the biases of ice concentration,ice cover,ice volume,and ice thickness can be reduced dramatically through ice concentration and thickness assimilation.The near-real-time forecast results indicate that ice data assimilation can improve the forecast skill significantly in the FIO-ESM climate forecast system.The forecasted Arctic integrated ice edge error is reduced by around 1/3 by sea ice data assimilation.Compared with the six near-real-time Arctic sea ice forecast results from the subseasonal-toseasonal(S2 S)Prediction Project,FIO-ESM climate forecast system with LESTKF ice data assimilation has relatively high Arctic sea ice forecast skill in 2018 summer sea ice forecast.Since sea ice thickness in the PIOMAS is updated in time,it is a good choice for data assimilation to improve sea ice prediction skills in the near-realtime Arctic sea ice seasonal prediction.展开更多
In this work, we addressed the inhomogeneity problem in gamma spectrometry caused by hot particles, which are dispersed into environment from large nuclear reactor accidents such as at Chernobyl and Fukushima. Using M...In this work, we addressed the inhomogeneity problem in gamma spectrometry caused by hot particles, which are dispersed into environment from large nuclear reactor accidents such as at Chernobyl and Fukushima. Using Monte Carlo simulation, we have determined the response of a gamma spectrometer to individual and grouped hot particles randomly distributed in a soil matrix of 1-L and 0.6-L sample containers. By exploring the fact that the peak-to-total ratio of efficiencies in gamma spectrometry is an empirical parameter, we derived and verified a power-law relationship between the peak efficiency and peak-to-total ratio. This enabled creation of a novel calibration model which was demonstrated to reduce the bias range and bias standard deviation, caused by measuring hot particles, by several times, as compared with the homogeneous calibration. The new model is independent of the number, location, and distribution of hot particles in the samples. In this work, we demonstrated successful performance of the model for a single-peak <sup>137</sup>Cs radionuclide. An extension to multi-peak radionuclide was also derived.展开更多
1 Background and purpose of workshop The Southern Ocean plays a fundamental role in the function of the Earth System,influencing climate,sea level,biogeochemical cycles,and biological productivity on a variety of scal...1 Background and purpose of workshop The Southern Ocean plays a fundamental role in the function of the Earth System,influencing climate,sea level,biogeochemical cycles,and biological productivity on a variety of scales[1].Observations from the Southern Ocean suggest that dramatic changes are taking place,which are展开更多
Several studies have compared outcomes for coronary-artery bypass grafting(CABG) and percutaneous coronary intervention(PCI), but most were done before the availability of stenting, which has revolutionized the latter...Several studies have compared outcomes for coronary-artery bypass grafting(CABG) and percutaneous coronary intervention(PCI), but most were done before the availability of stenting, which has revolutionized the latter approach. METHODS: We used New York’ s cardiac registries to identify 37,212 patients with multivessel disease who underwent CABG and 22,102 patients with multivessel disease who underwent PCI from January 1, 1997, to December 31, 2000. We determined the rates of death and subsequent revascularization within three years after the procedure in various groups of patients according to the number of diseased vessels and the presence or absence of involvement of the left anterior descending coronary artery. The rates of adverse outcomes were adjusted by means of proportional-hazards methods to account for differences in patients’ severity of illness before revascularization. RESULTS: Risk-adjusted survival rates were significantly higher among patients who underwent CABG than among those who received a stent in all of the anatomical subgroups studied. For example, the adjusted hazard ratio for the long-term risk of death after CABG relative to stent implantation was 0.64(95 percent confidence interval, 0.56 to 0.74) for patients with three-vessel disease with involvement of the proximal left anterior descending coronary artery and 0.76(95 percent confidence interval, 0.60 to 0.96) for patients with two-vessel disease with involvement of the nonproximal left anterior descending coronary artery. Also, the three-year rates of revascularization were considerably higher in the stenting group than in the CABG group(7.8 percent vs. 0.3 percent for subsequent CABG and 27.3 percent vs. 4.6 percent for subsequent PCI). CONCLUSIONS: For patients with two or more diseased coronary arteries, CABG is associated with higher adjusted rates of long-term survival than stenting.展开更多
This paper describes the latest progress of a collaborative research program entitled "Modeling Aerosol Climate Effects over Monsoon Asia", under the Climate Sciences agreement between the U.S. Department of...This paper describes the latest progress of a collaborative research program entitled "Modeling Aerosol Climate Effects over Monsoon Asia", under the Climate Sciences agreement between the U.S. Department of Energy and the Chinese Academy of Sciences(in the early 1980 s, Professor Duzheng YE played a critical role in leading and formalizing the agreement). Here, the rationale and approach for pursuing the program, the participants, and research activities of recent years are first described, and then the highlights of the program's key findings and relevant scientific issues, as well as follow-up studies, are presented and discussed.展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos. 41421004 and 41210007)
文摘Air quality in eastern China has becoming more and more worrying in recent years, and haze is now No.1 air pollution issue. Results in this study show the decreasing Arctic sea ice(ASI) is an important contributor to the recent increased haze days in eastern China. The authors find that the number of winter haze days(WHD) in eastern China is strongly negatively correlated with the preceding autumn ASI during 1979–2012, and about 45%– 67% of the WHD interannual to interdecadal variability can be explained by ASI variability. Following previous studies on the impact of ASI loss on the northern hemisphere climate, the authors' studies further reveal that the reduction of autumn ASI leads to positive sea-level pressure anomalies in mid-latitude Eurasia, northward shift of track of cyclone activity in China, and weak Rossby wave activity in eastern China south of 40N during winter season. These atmospheric circulation changes favor less cyclone activity and more stable atmosphere in eastern China, leading to more haze days there. Furthermore, the patterns of circulation changes associated with autumn ASI and WHD are in very good agreement over the East Asia, particularly in eastern China. The authors suggest that haze pollution may continue to be a serious issue in the near future as the decline of ASI continues under global warming.
基金the ARM program sponsored by the U.S. DOEsupported by the National Natural Science Foundation of China (Grant Nos. 40975001 and 61327810)+2 种基金the Special Fund for Public Welfare Industry (Meteorology) (Grant No. GYHY201106046)the support of a grant (to SUNYA) from the Office of Science (BER),U.S. DOEthe Key National Basic Research Program on Global Change (Grant No. 2013CB955803)
文摘By using the radiosonde measurements collected at Shouxian,China,we examined the dynamics and thermodynamics of single- and two-layer clouds formed at low and middle levels.The analyses indicated that the horizontal wind speed above the cloud layers was higher than those within and below cloud layers.The maximum balloon ascent speed(5.3 m s^(-1)) was located in the vicinity of the layer with the maximum cloud occurrence frequency(24.4%),indicating an upward motion(0.1-0.16 ms^(-1)).The average thickness,magnitude and gradient of the temperature inversion layer above single-layer clouds were117±94 m,1.3±1.3℃ and 1.4±1.5℃(100 m)^(-1),respectively.The average temperature inversion magnitude was the same(1.3℃) for single-low and single-middle clouds;however,a larger gradient[1.7±1.8℃(100 m)^(-1)]and smaller thickness(94±67 m) were detected above single-low clouds relative to those above single-middle clouds[0.9±0.7℃(100 m)^(-1) and157±120 m].For the two-layer cloud,the temperature inversion parameters were 106±59 m,1.0±0.9℃ and 1.0±1.0℃(100 m)^(-1) above the upper-layer cloud and 82 ± 60 m,0.6±0.9℃ and 0.7±0.6℃(100 m)^(-1) above the low-layer cloud.Absolute differences between the cloud-base height(cloud-top height) and the lifting condensation level(equilibrium level)were less than 0.5 km for 66.4%(36.8%) of the cases analyzed in summer.
基金the National Key R&D Program of China(2018YFA0605901)Y.XIA and Y.Y.HU are supported by the National Natural Science Foundation of China(NSFC)(Grant Nos.41530423 and 41761144072)+4 种基金Y.XIA is supported by the China Postdoctoral Science Foundation funded project(Grant No.2018M630027)Y.HUANG is supported by the Discovery Program of the Natural Sciences and Engineering Council of Canada(Grant No.RGPIN 418305-13)the Team Research Project Program of the Fonds de RechercheNature et Technologies of Quebec(Grant No.PR-190145)J.P.LIU is supported by the Climate Observation and Earth System Science Divisions,Climate Program Office,NOAA,U.S.Department of Commerce(Grant Nos.NA15OAR4310163 and NA14OAR4310216)J.T.LIN is supported by the NSFC(Grant No.41775115)and the 973 program(Grant No.2014CB441303).
文摘Recent studies demonstrate that the Antarctic Ozone Hole has important influences on Antarctic sea ice.While most of these works have focused on effects associated with atmospheric and oceanic dynamic processes caused by stratospheric ozone changes,here we show that stratospheric ozone-induced cloud radiative effects also play important roles in causing changes in Antarctic sea ice.Our simulations demonstrate that the recovery of the Antarctic Ozone Hole causes decreases in clouds over Southern Hemisphere(SH)high latitudes and increases in clouds over the SH extratropics.The decrease in clouds leads to a reduction in downward infrared radiation,especially in austral autumn.This results in cooling of the Southern Ocean surface and increasing Antarctic sea ice.Surface cooling also involves ice-albedo feedback.Increasing sea ice reflects solar radiation and causes further cooling and more increases in Antarctic sea ice.
基金supported by the National Natural Science Foundation of China[grant number 41176169]the National Basic Research Program of China[grant number 2011CB309704]
基金supported by the National Key Basic Research Project of China (Grant nos.2013CBA01804,2015CB453200)the National Natural Science Foundation of China (Grant nos.41475080,41221064)the Ocean Public Welfare Scientific Research Project of China (Grant no.201205007)
文摘Dominant statistical patterns of winter Arctic surface wind(WASW) variability and their impacts on Arctic sea ice motion are investigated using the complex vector empirical orthogonal function(CVEOF) method. The results indicate that the leading CVEOF of Arctic surface wind variability, which accounts for 33% of the covariance, is characterized by two different and alternating spatial patterns(WASWP1 and WASWP2). Both WASWP1 and WASWP2 show strong interannual and decadal variations, superposed on their declining trends over past decades. Atmospheric circulation anomalies associated with WASWP1 and WASWP2 exhibit, respectively, equivalent barotropic and some baroclinic characteristics, differing from the Arctic dipole anomaly and the seesaw structure anomaly between the Barents Sea and the Beaufort Sea. On decadal time scales, the decline trend of WASWP2 can be attributed to persistent warming of sea surface temperature in the Greenland—Barents—Kara seas from autumn to winter, reflecting the effect of the Arctic warming. The second CVEOF, which accounts for 18% of the covariance, also contains two different spatial patterns(WASWP3 and WASWP4). Their time evolutions are significantly correlated with the North Atlantic Oscillation(NAO) index and the central Arctic Pattern, respectively, measured by the leading EOF of winter sea level pressure(SLP) north of 70°N. Thus, winter anomalous surface wind pattern associated with the NAO is not the most important surface wind pattern. WASWP3 and WASWP4 primarily reflect natural variability of winter surface wind and neither exhibits an apparent trend that differs from WASWP1 or WASWP2. These dominant surface wind patterns strongly influence Arctic sea ice motion and sea ice exchange between the western and eastern Arctic. Furthermore, the Fram Strait sea ice volume flux is only significantly correlated with WASWP3. The results demonstrate that surface and geostrophic winds are not interchangeable in terms of describing wind field variability over the Arctic Ocean. The results have important implications for understanding and investigating Arctic sea ice variations: Dominant patterns of Arctic surface wind variability, rather than simply whether there are the Arctic dipole anomaly and the Arctic Oscillation(or NAO), effectively affect the spatial distribution of Arctic sea ice anomalies.
基金supported by National Institute of Health grants U01 AI061193 and U54-AI057158 (Northeast Biodefense Center).
文摘Many flaviviruses are emerging and reemerging pathogens,such as West Nile virus(WNV) ,dengue virus(DENV) ,yellow fever virus(YFV) ,and Japanese encephalitis virus. Serological assay is the dominant method for diagnosis of flavivirus infections in human. Because antibodies generated during flavivirus infections cross-react with other flavivirus members,plaque reduction neutralization test(PRNT) is the only available assay to determine the infecting flavivirus type. Since PRNT requires culturing raw viruses,it must be performed in biosafety level-3 or level-4 containment for many flaviviruses,and takes more than ten days to complete. To overcome these problems,we have developed flavivirus viral-like particles(VLPs) that could be used to replace raw viruses in the neutralization assay. The VLPs were prepared by trans packaging a luciferase-reporting replicon with viral structural proteins. This novel assay involves three simple steps:(i) VLPs from a panel of flaviviruses are incubated with flavivirus-infected sera at 37℃ for 1 h;(ii) the neutralized VLPs are used to infect Vero cells;and(iii) the infected cells are measured for luciferase activities at 22 h post-infection. The virus type whose VLP is most efficiently neutralized by the serum specimen(as quantified by the luciferase activities) is the etiologic agent. As a proof-of-concept,we show that a WNV-infected mouse serum neutralized the WNV VLP more efficiently and selectively than the DENV and YFV VLPs. Our results demonstrate that the VLP neutralization assay maintains the "gold standard" of the classic PRNT;importantly,it shortens the assay time from >10 days to <1 day,and can be performed in biosafety level-2 facility.
文摘Determining the species of origin of skeletal remains is critical in a forensic and anthropologic context. However, there are very few methods that use a chemical approach to assist in this determination. In this study, Raman spectroscopy was used to discriminate bone samples originating from four different species (bovine, porcine, turkey and chicken). Spectra were obtained using a near infrared laser at 785-nm. All spectra were combined in a single matrix and processed using partial least squares discriminate analysis (PLS-DA) with leave-one-out cross-validation. Three com-ponents were found to adequately describe the system. The first two components which contributed over 85% of spec-tral data was seen to completely separate the four species of origin in a two dimensional scores plot. A 95% confidence interval was draw around score points of each species class with very slight overlap. The first two components were seen to have large contributions from bioapatite and collagen, the main components of bone. This study serves as a preliminary investigation to evaluate the effectiveness of Raman spectroscopy to discriminate the species of origin of bone tissue.
文摘OBJECTIVE Hybrid coronary revascularization(HCR)combines a minimally invasive surgical approach to the left anterior descending(LAD)artery with percutaneous coronary intervention(PCI)for non-LAD diseased coronary arteries.It is associated with shorter hospital lengths of stay and recovery times than conventional coronary artery bypass surgery,but there is little information comparing it to isolated PCI for multivessel disease.Our objective is to compare long-term outcomes of HCR and PCI for patients with multivessel disease.METHODS This cohort study used data from New York’s cardiac surgery and PCI registries in 2010−2016 to examine mortality and repeat revascularization rates for patients with multivessel coronary artery disease who underwent HCR and PCI.Cox proportional hazards methods were used to reduce selection bias.Patients were followed for a median of four years.RESULTS There was a total of 335 HCR patients(1.2%)and 25,557 PCI patients(98.8%)after exclusions.There was no difference in 6-year risk adjusted survival between HCR and PCI patients 83.17%vs.81.65%,adjusted hazard ratio(aHR)=0.90(95%CI:0.67−1.20).However,HCR patients were more likely to be free from repeat revascularization in the LAD artery(91.13%vs.83.59%,aHR=0.51(95%CI:0.34−0.77)).CONCLUSIONS For patients with multi-vessel coronary artery disease,HCR is rarely performed.There are no differences in mortality rates after four years,but HCR is associated with lower repeat revascularization rates in the LAD artery,presumably due to better longevity in left arterial mammary grafts.
基金supported by the National Natural Science Foundation of China(Grant Nos.41941009,41922044,and 42006191)the Guangdong Basic and Applied Basic Research Foundation(Grant No.2020B1515020025)+1 种基金the Fundamental Research Funds for the Central Universities(Grant No.19lgzd07)the Norges Forskningsråd(Grant no.328886).
文摘Seasonal minimum Antarctic sea ice extent(SIE)in 2022 hit a new record low since recordkeeping began in 1978 of 1.9 million km^(2) on 25 February,0.17 million km^(2) lower than the previous record low set in 2017.Significant negative anomalies in the Bellingshausen/Amundsen Seas,the Weddell Sea,and the western Indian Ocean sector led to the new record minimum.The sea ice budget analysis presented here shows that thermodynamic processes dominate sea ice loss in summer through enhanced poleward heat transport and albedo-temperature feedback.In spring,both dynamic and thermodynamic processes contribute to negative sea ice anomalies.Specifically,dynamic ice loss dominates in the Amundsen Sea as evidenced by sea ice thickness(SIT)change,while positive surface heat fluxes contribute most to sea ice melt in the Weddell Sea.
基金supported by the Key Research Program of Frontier Sciences,CAS (Grant No. ZDBS-LY-DQC010)the National Natural Science Foundation of China (Grant Nos. 41876012 and 41861144015,42175045)the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No.XDB42000000).
文摘Several consecutive extreme cold events impacted China during the first half of winter 2020/21,breaking the low-temperature records in many cities.How to make accurate climate predictions of extreme cold events is still an urgent issue.The synergistic effect of the warm Arctic and cold tropical Pacific has been demonstrated to intensify the intrusions of cold air from polar regions into middle-high latitudes,further influencing the cold conditions in China.However,climate models failed to predict these two ocean environments at expected lead times.Most seasonal climate forecasts only predicted the 2020/21 La Niña after the signal had already become apparent and significantly underestimated the observed Arctic sea ice loss in autumn 2020 with a 1-2 month advancement.In this work,the corresponding physical factors that may help improve the accuracy of seasonal climate predictions are further explored.For the 2020/21 La Niña prediction,through sensitivity experiments involving different atmospheric-oceanic initial conditions,the predominant southeasterly wind anomalies over the equatorial Pacific in spring of 2020 are diagnosed to play an irreplaceable role in triggering this cold event.A reasonable inclusion of atmospheric surface winds into the initialization will help the model predict La Niña development from the early spring of 2020.For predicting the Arctic sea ice loss in autumn 2020,an anomalously cyclonic circulation from the central Arctic Ocean predicted by the model,which swept abnormally hot air over Siberia into the Arctic Ocean,is recognized as an important contributor to successfully predicting the minimum Arctic sea ice extent.
基金The National Key Research and Development Program of China under contract Nos 2018YFC1407205 and2018YFA0605901the Basic Scientific Fund for National Public Research Institute of China(ShuXingbei Young Talent Program)under contract No.2019S06+1 种基金the National Natural Science Foundation of China under contract Nos 41821004,42022042 and 41941012the China-Korea Cooperation Project on Northwestern Pacific Climate Change and its Prediction。
文摘To improve the Arctic sea ice forecast skill of the First Institute of Oceanography-Earth System Model(FIO-ESM)climate forecast system,satellite-derived sea ice concentration and sea ice thickness from the Pan-Arctic IceOcean Modeling and Assimilation System(PIOMAS)are assimilated into this system,using the method of localized error subspace transform ensemble Kalman filter(LESTKF).Five-year(2014–2018)Arctic sea ice assimilation experiments and a 2-month near-real-time forecast in August 2018 were conducted to study the roles of ice data assimilation.Assimilation experiment results show that ice concentration assimilation can help to get better modeled ice concentration and ice extent.All the biases of ice concentration,ice cover,ice volume,and ice thickness can be reduced dramatically through ice concentration and thickness assimilation.The near-real-time forecast results indicate that ice data assimilation can improve the forecast skill significantly in the FIO-ESM climate forecast system.The forecasted Arctic integrated ice edge error is reduced by around 1/3 by sea ice data assimilation.Compared with the six near-real-time Arctic sea ice forecast results from the subseasonal-toseasonal(S2 S)Prediction Project,FIO-ESM climate forecast system with LESTKF ice data assimilation has relatively high Arctic sea ice forecast skill in 2018 summer sea ice forecast.Since sea ice thickness in the PIOMAS is updated in time,it is a good choice for data assimilation to improve sea ice prediction skills in the near-realtime Arctic sea ice seasonal prediction.
文摘In this work, we addressed the inhomogeneity problem in gamma spectrometry caused by hot particles, which are dispersed into environment from large nuclear reactor accidents such as at Chernobyl and Fukushima. Using Monte Carlo simulation, we have determined the response of a gamma spectrometer to individual and grouped hot particles randomly distributed in a soil matrix of 1-L and 0.6-L sample containers. By exploring the fact that the peak-to-total ratio of efficiencies in gamma spectrometry is an empirical parameter, we derived and verified a power-law relationship between the peak efficiency and peak-to-total ratio. This enabled creation of a novel calibration model which was demonstrated to reduce the bias range and bias standard deviation, caused by measuring hot particles, by several times, as compared with the homogeneous calibration. The new model is independent of the number, location, and distribution of hot particles in the samples. In this work, we demonstrated successful performance of the model for a single-peak <sup>137</sup>Cs radionuclide. An extension to multi-peak radionuclide was also derived.
基金hosted and sponsored by the Polar Research Institute of China (PRIC), with additional sponsorship by the State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics (LASG), Institute of Atmospheric Physics, Chinese Academy of Sciences (IAP/CAS), the World Climate Research Programme (WCRP) "Climate and the Cryosphere" project (CliC), the Scientific Committee on Antarctic Research (SCAR), and the Scientific Committee on Oceanic Research (SCOR). SOOS acknowledges the support of its host institute, the Institute for Marine and Antarctic Studies (IMAS, University of Tasmania, Australia), and sponsors, Australian Antarctic Division, Antarctica New Zealand, and the New Zealand Antarctic Research Institute.
文摘1 Background and purpose of workshop The Southern Ocean plays a fundamental role in the function of the Earth System,influencing climate,sea level,biogeochemical cycles,and biological productivity on a variety of scales[1].Observations from the Southern Ocean suggest that dramatic changes are taking place,which are
文摘Several studies have compared outcomes for coronary-artery bypass grafting(CABG) and percutaneous coronary intervention(PCI), but most were done before the availability of stenting, which has revolutionized the latter approach. METHODS: We used New York’ s cardiac registries to identify 37,212 patients with multivessel disease who underwent CABG and 22,102 patients with multivessel disease who underwent PCI from January 1, 1997, to December 31, 2000. We determined the rates of death and subsequent revascularization within three years after the procedure in various groups of patients according to the number of diseased vessels and the presence or absence of involvement of the left anterior descending coronary artery. The rates of adverse outcomes were adjusted by means of proportional-hazards methods to account for differences in patients’ severity of illness before revascularization. RESULTS: Risk-adjusted survival rates were significantly higher among patients who underwent CABG than among those who received a stent in all of the anatomical subgroups studied. For example, the adjusted hazard ratio for the long-term risk of death after CABG relative to stent implantation was 0.64(95 percent confidence interval, 0.56 to 0.74) for patients with three-vessel disease with involvement of the proximal left anterior descending coronary artery and 0.76(95 percent confidence interval, 0.60 to 0.96) for patients with two-vessel disease with involvement of the nonproximal left anterior descending coronary artery. Also, the three-year rates of revascularization were considerably higher in the stenting group than in the CABG group(7.8 percent vs. 0.3 percent for subsequent CABG and 27.3 percent vs. 4.6 percent for subsequent PCI). CONCLUSIONS: For patients with two or more diseased coronary arteries, CABG is associated with higher adjusted rates of long-term survival than stenting.
基金support by a grant from the Office of Sciences(BER),U.S.DOEsupport from the Key National Basic Research Program on Global Change(Grant No.2013CB955803)to facilitate the visits to Peking University and the Institute of Atmospheric Physics
文摘This paper describes the latest progress of a collaborative research program entitled "Modeling Aerosol Climate Effects over Monsoon Asia", under the Climate Sciences agreement between the U.S. Department of Energy and the Chinese Academy of Sciences(in the early 1980 s, Professor Duzheng YE played a critical role in leading and formalizing the agreement). Here, the rationale and approach for pursuing the program, the participants, and research activities of recent years are first described, and then the highlights of the program's key findings and relevant scientific issues, as well as follow-up studies, are presented and discussed.
