Fire is a fundamental ecological driver shaping natural vegetation patterns.In the semi-arid southern Espinal-Monte ecotone of Argentina,the spatiotemporal patterns of fire occurrence related to and modulated by clima...Fire is a fundamental ecological driver shaping natural vegetation patterns.In the semi-arid southern Espinal-Monte ecotone of Argentina,the spatiotemporal patterns of fire occurrence related to and modulated by climatic gradients and antecedent conditions are not well researched.This study examined fire occurrence in the semi-arid southern Espinal-Monte ecotone(southeastern La Pampa,northeastern Río Negro,and southwestern Buenos Aires with an area of 68×103 km2)of Argentina,a key environmental transition zone with pronounced climatic and vegetation gradients.The objective was to identify the spatiotemporal patterns of fire occurrence and their relationship with climatic variables.Thermal anomaly(TA)data from the MODIS(Moderate Resolution Imaging Spectrometer;MOD14)sensor(November 2000–March 2020)with confidence levels>65.0%were analyzed.Climatic variables(rainfall isohyets and aridity indices)were obtained from the WorldClim datasets,and annual meteorological conditions(rainfall and potential evapotranspiration)were calculated using the climatic research unit(CRU)database.Monthly data and moving averages of rainfall and aridity indices from distinct periods(two and three years preceding fire events)were integrated.Spatial analysis was conducted using kernel density estimation on a 10 km×10 km grid to correlate TA with climatic gradients,while linear regression examined relationships between summer TA and meteorological variables over different periods.Results showed that the highest fire occurrence was recorded in summer,with peaks in December and January.Spatially,55.0%of TA occurred in areas with annual rainfall of 300–400 mm,and 64.5%in areas with an aridity index of 0.3–0.4,forming an arc-like distribution in the center of the ecotone.The highest TA densities were observed in southeastern La Pampa and northeastern Río Negro,decreasing toward southwestern Buenos Aires.Significant correlations(R2>0.700)were found among TA accumulation,aridity index values,and cumulative rainfall from previous two and three years,at both vegetation unit and provincial levels.Summer was the critical season for fire occurrence,with spatial distribution primarily determined by the interaction between climatic conditions and woody biomass availability.The lower fire incidence in southwestern Buenos Aires was linked to sparse woody vegetation and agricultural expansion,which reduced fuel load.These findings reinforce that fuel availability,modulated by climatic conditions from previous years,is a key limiting factor for fire dynamics in this area,and that human activities such as agriculture and grazing alter fire regimes by affecting fuel structure and continuity.展开更多
Lightweight nodes are crucial for blockchain scalability,but verifying the availability of complete block data puts significant strain on bandwidth and latency.Existing data availability sampling(DAS)schemes either re...Lightweight nodes are crucial for blockchain scalability,but verifying the availability of complete block data puts significant strain on bandwidth and latency.Existing data availability sampling(DAS)schemes either require trusted setups or suffer from high communication overhead and low verification efficiency.This paper presents ISTIRDA,a DAS scheme that lets light clients certify availability by sampling small random codeword symbols.Built on ISTIR,an improved Reed–Solomon interactive oracle proof of proximity,ISTIRDA combines adaptive folding with dynamic code rate adjustment to preserve soundness while lowering communication.This paper formalizes opening consistency and prove security with bounded error in the random oracle model,giving polylogarithmic verifier queries and no trusted setup.In a prototype compared with FRIDA under equal soundness,ISTIRDA reduces communication by 40.65%to 80%.For data larger than 16 MB,ISTIRDA verifies faster and the advantage widens;at 128 MB,proofs are about 60%smaller and verification time is roughly 25%shorter,while prover overhead remains modest.In peer-to-peer emulation under injected latency and loss,ISTIRDA reaches confidence more quickly and is less sensitive to packet loss and load.These results indicate that ISTIRDA is a scalable and provably secure DAS scheme suitable for high-throughput,large-block public blockchains,substantially easing bandwidth and latency pressure on lightweight nodes.展开更多
Heart transplantation is a life-saving procedure for many people throughout the world.Data shows that in 2024,there was an increase in the volume of adult heart transplantation in the United States even as there was a...Heart transplantation is a life-saving procedure for many people throughout the world.Data shows that in 2024,there was an increase in the volume of adult heart transplantation in the United States even as there was a decrease in the volume of pediatric heart transplantation to the lowest volume in a decade.Organ availability remains a major limiting factor affecting transplant volume.This mandates that innovation must take place to increase the supply of donor organs.While some strategies such as donation after cardiac death,hepatitis C virus+transplantation,and ABO-incompatible transplantation have increased the pool for donation,it still falls short of meeting the demand.Other proposed strategies include splitting the donor heart to provide multiple partial heart transplants,domino partial heart transplantation,changes in legislation including opt-out legislation,and xenotransplantation.Further evolution and refinement of these strategies will make a meaningful impact on patients awaiting life-saving heart transplants.展开更多
The Reference Listed drug(RLD)plays a critical role in the development and research of generic medicinal products,serving as the comparator product used in the marketing authorization application of new generic medici...The Reference Listed drug(RLD)plays a critical role in the development and research of generic medicinal products,serving as the comparator product used in the marketing authorization application of new generic medicinal product and re-evaluation of generic medicinal product.In China,RLDs are sourced from various origins,but their quality and market availability can be constrained by multiple factors,including emergent issues such as nitrosamine impurities.Five classes of medicinal products have been reported to be at risk for containing nitrosamine impurities:sartan-based medicines,metformin-containing products,ranitidine medicines,rifampicin medicines,and Champix.This paper explores the control strategies implemented by drug regulatory agencies in the United States and the European Union to manage nitrosamine impurities and assesses their impact on the market availability and quality of RLDs in China.The aim is to offer valuable insights for generic drug manufacturers and regulatory bodies both domestically and internationally.展开更多
Recent work analysing magnesium hydrogenation using Reflecting Electron Energy Loss Spectroscopy(REELS)and Density Function Theory(DFT)has indicated interfacial polarisation and interstitial hydrogen clustering influe...Recent work analysing magnesium hydrogenation using Reflecting Electron Energy Loss Spectroscopy(REELS)and Density Function Theory(DFT)has indicated interfacial polarisation and interstitial hydrogen clustering influence the reaction rate.The site availability model has been modified to include interstitial hydrogen clustering within the site availability factor and interface polarisation using interface treatment.The new model,SAM-CV-S,has demonstrated improved modelling of magnesium hydrogenation across wide operating conditions,such as temperatures from 330 to 400℃and pressures up to 40 bar.This wide applicability makes it a robust model that can be used to simulate bed performance in solid-state hydrogen stores.Thus,the site availability factor successfully combines interstitial hydrogen clustering with thermal resistance effects,which are known to strongly influence metal hydride reactor designs at scale.The next phase of the model is to incorporate a predictive hydrogen capacity method into the model.展开更多
Four different methods,namely mineralogical analysis,three-stage BCR sequential extraction procedure,dynamic leaching test and Hakanson Potential Ecological Risk Index Method were used to access the environmental acti...Four different methods,namely mineralogical analysis,three-stage BCR sequential extraction procedure,dynamic leaching test and Hakanson Potential Ecological Risk Index Method were used to access the environmental activity and potential ecological risks of heavy metals in zinc leaching residue.The results demonstrate that the environmental activity of heavy metals declines in the following order：CdZnCuAsPb.Potential ecological risk indices for single heavy metal are CdZnCuAsPb.Cd has serious potential ecological risk to the ecological environment and contributes most to the potential toxicity response indices for various heavy metals in the residue.展开更多
A multi-component system has the long fixed maintenance time, so the opportunistic maintenance policy is adopted to put preventive replacement and corrective replacement together, so that the long fixed maintenance ti...A multi-component system has the long fixed maintenance time, so the opportunistic maintenance policy is adopted to put preventive replacement and corrective replacement together, so that the long fixed maintenance time can be shared by more than one component, and the system availability can be improved. Then, the generation characteristics of the random failure time are researched based on the replacement maintenance and the minima[ maintenance. Furthermore, by choosing the opportunistic replacement ages of each component as opti- mized variables, a simulation algorithm based on an opportunistic maintenance policy is designed to maximize the total availability. Finally, the simulation result shows the validity of the algorithm by an example.展开更多
A laboratory simulated freeze-thaw was conducted to determine the effects of freeze-thaw on soil nutrient availability in temperate semi-arid regions. Soil samples were collected from sandy soils （0-20 cm） of three ...A laboratory simulated freeze-thaw was conducted to determine the effects of freeze-thaw on soil nutrient availability in temperate semi-arid regions. Soil samples were collected from sandy soils （0-20 cm） of three typical ecosystems （grassland, Mongolian pine plantation and poplar plantation） in southeastern Keerqin Sandy Lands of China and subjected to freeze-thaw treatment （-12℃ for 10 days, then r 20℃ for 10 days） or incubated at constant temperature （20℃ for 20 days）. Concentrations of the soil NO3^--N, NH4^＋-N, NaHCO3 extractable inorganic P （LPi） and microbial biomass P （MBP） were determined on three occasions： at the start of the incubation, immediate post-thawing and at the 10th day post-thawing. The results showed that soil net nitrification and N mineralization rates at three sites were negatively affected by freeze-thaw treatment, and decreased by 50%-85% as compared to the control, of which the greatest decline occurred in the soil collected from poplar plantation. In contrast, the concentration of soil NH4^＋-N, NaHCO3 extractable inorganic P （LPi） and microbial biomass P were insignificantly influenced by freeze-thaw except that LPi and NH4^＋-N showed a slight increase immediate post-thawing. The effects of freeze-thaw on soil N transformation were related to soil biological processes and the relatively constant available P was ascribed to severe soil aridity.展开更多
Based on the assay of the total content and available content of the trace nutrient elements and the soil pH and organic matter of the soil samples,the characteristic of the available content of the trace nutrient ele...Based on the assay of the total content and available content of the trace nutrient elements and the soil pH and organic matter of the soil samples,the characteristic of the available content of the trace nutrient elements and their affecting factors are studied. The results show that the available B in western Jilin is in a middle level,the content in Nong'an is higher than that in the others; the available Mn is extremely abundant; the available Cu in Nong'an is obviously higher than other areas,and the content in Da'an differs greatly; the available Zn is in a middle level; the severe shortage of available Mo differs between different areas; and the available Fe is extremely abundant. The available Mn,Cu and Fe have significantly positive correlation with their total content; the available B has significantly positive correlation with pH,and Zn has obviously negative correlation with pH; the available Mn and Fe had significantly positive correlation with soil organic matter.展开更多
To cope with the problem of low protocol efficiency of the standard ad hoc on-demand distance vector （AODV） routing protocol with the periodic Hello message broadcast mechanism, a new link availability prediction ba...To cope with the problem of low protocol efficiency of the standard ad hoc on-demand distance vector （AODV） routing protocol with the periodic Hello message broadcast mechanism, a new link availability prediction based strategy is introduced to reduce the amount of Hello messages. In this strategy, a novel wireless link availability prediction model under line-of-sight （LOS） propagation environments is proposed based on which the parameter of Hello Interval in AODV can be dynamically adjusted to achieve the goal of changing the frequency of Hello message broadcasts under different link stability degrees. Simulation results demonstrate that, compared with the standard AODV with the periodic Hello message broadcast mechanism, the proposed protocol effectively reduces unnecessary control message overhead and greatly improves the performance in terms of end-to-end delay and efficiency.展开更多
Through indoor culture experiments, the effects of continuous irrigation of biogas slurry on the forms and biological availability of Pb in soil of a tea garden were studied. The results show that continuous irrigatio...Through indoor culture experiments, the effects of continuous irrigation of biogas slurry on the forms and biological availability of Pb in soil of a tea garden were studied. The results show that continuous irrigation of biogas slurry could change the forms of Pb in the soil, and exchangeable Pb, Pb bonded to iron and manganese oxides, and Pb bonded to carbonates transformed to Pb bonded to or- ganic matter and residual Pb in the soil. Among various forms of Pb in the soil, the content of residual Pb was the highest in the soil irrigated with biogas slurry contin- uously in various treatments, accounting for 54.56%, 60.00% and 60.70% in the treatments T1, T2 and T3 respectively. Compared with the CK, the application of bio- gas slurry could decrease the biological activity and biological availability of Pb in the soil obviously, and the reduction of the biological activity was 21.26%-22.83%. In a word, the application of biogas slurry in soil of the tea garden could inhibit the biological activity and biological availability of Pb.展开更多
基金funded by the National University of Río Negro Research Project (40-C-658)
文摘Fire is a fundamental ecological driver shaping natural vegetation patterns.In the semi-arid southern Espinal-Monte ecotone of Argentina,the spatiotemporal patterns of fire occurrence related to and modulated by climatic gradients and antecedent conditions are not well researched.This study examined fire occurrence in the semi-arid southern Espinal-Monte ecotone(southeastern La Pampa,northeastern Río Negro,and southwestern Buenos Aires with an area of 68×103 km2)of Argentina,a key environmental transition zone with pronounced climatic and vegetation gradients.The objective was to identify the spatiotemporal patterns of fire occurrence and their relationship with climatic variables.Thermal anomaly(TA)data from the MODIS(Moderate Resolution Imaging Spectrometer;MOD14)sensor(November 2000–March 2020)with confidence levels>65.0%were analyzed.Climatic variables(rainfall isohyets and aridity indices)were obtained from the WorldClim datasets,and annual meteorological conditions(rainfall and potential evapotranspiration)were calculated using the climatic research unit(CRU)database.Monthly data and moving averages of rainfall and aridity indices from distinct periods(two and three years preceding fire events)were integrated.Spatial analysis was conducted using kernel density estimation on a 10 km×10 km grid to correlate TA with climatic gradients,while linear regression examined relationships between summer TA and meteorological variables over different periods.Results showed that the highest fire occurrence was recorded in summer,with peaks in December and January.Spatially,55.0%of TA occurred in areas with annual rainfall of 300–400 mm,and 64.5%in areas with an aridity index of 0.3–0.4,forming an arc-like distribution in the center of the ecotone.The highest TA densities were observed in southeastern La Pampa and northeastern Río Negro,decreasing toward southwestern Buenos Aires.Significant correlations(R2>0.700)were found among TA accumulation,aridity index values,and cumulative rainfall from previous two and three years,at both vegetation unit and provincial levels.Summer was the critical season for fire occurrence,with spatial distribution primarily determined by the interaction between climatic conditions and woody biomass availability.The lower fire incidence in southwestern Buenos Aires was linked to sparse woody vegetation and agricultural expansion,which reduced fuel load.These findings reinforce that fuel availability,modulated by climatic conditions from previous years,is a key limiting factor for fire dynamics in this area,and that human activities such as agriculture and grazing alter fire regimes by affecting fuel structure and continuity.
基金supported in part by the Research Fund of Key Lab of Education Blockchain and Intelligent Technology,Ministry of Education(EBME25-F-08).
文摘Lightweight nodes are crucial for blockchain scalability,but verifying the availability of complete block data puts significant strain on bandwidth and latency.Existing data availability sampling(DAS)schemes either require trusted setups or suffer from high communication overhead and low verification efficiency.This paper presents ISTIRDA,a DAS scheme that lets light clients certify availability by sampling small random codeword symbols.Built on ISTIR,an improved Reed–Solomon interactive oracle proof of proximity,ISTIRDA combines adaptive folding with dynamic code rate adjustment to preserve soundness while lowering communication.This paper formalizes opening consistency and prove security with bounded error in the random oracle model,giving polylogarithmic verifier queries and no trusted setup.In a prototype compared with FRIDA under equal soundness,ISTIRDA reduces communication by 40.65%to 80%.For data larger than 16 MB,ISTIRDA verifies faster and the advantage widens;at 128 MB,proofs are about 60%smaller and verification time is roughly 25%shorter,while prover overhead remains modest.In peer-to-peer emulation under injected latency and loss,ISTIRDA reaches confidence more quickly and is less sensitive to packet loss and load.These results indicate that ISTIRDA is a scalable and provably secure DAS scheme suitable for high-throughput,large-block public blockchains,substantially easing bandwidth and latency pressure on lightweight nodes.
文摘Heart transplantation is a life-saving procedure for many people throughout the world.Data shows that in 2024,there was an increase in the volume of adult heart transplantation in the United States even as there was a decrease in the volume of pediatric heart transplantation to the lowest volume in a decade.Organ availability remains a major limiting factor affecting transplant volume.This mandates that innovation must take place to increase the supply of donor organs.While some strategies such as donation after cardiac death,hepatitis C virus+transplantation,and ABO-incompatible transplantation have increased the pool for donation,it still falls short of meeting the demand.Other proposed strategies include splitting the donor heart to provide multiple partial heart transplants,domino partial heart transplantation,changes in legislation including opt-out legislation,and xenotransplantation.Further evolution and refinement of these strategies will make a meaningful impact on patients awaiting life-saving heart transplants.
基金Subject construction funding project of Institute for Chemical Drug Control(Grant No.2024HYZX42)in National Institutes for Food and Drug Control,Beijing,China。
文摘The Reference Listed drug(RLD)plays a critical role in the development and research of generic medicinal products,serving as the comparator product used in the marketing authorization application of new generic medicinal product and re-evaluation of generic medicinal product.In China,RLDs are sourced from various origins,but their quality and market availability can be constrained by multiple factors,including emergent issues such as nitrosamine impurities.Five classes of medicinal products have been reported to be at risk for containing nitrosamine impurities:sartan-based medicines,metformin-containing products,ranitidine medicines,rifampicin medicines,and Champix.This paper explores the control strategies implemented by drug regulatory agencies in the United States and the European Union to manage nitrosamine impurities and assesses their impact on the market availability and quality of RLDs in China.The aim is to offer valuable insights for generic drug manufacturers and regulatory bodies both domestically and internationally.
基金funded through Engineering and Physical Sciences Research Council(EPSRC)[grant numbers EP/W005131/1,EP/V042556/1].
文摘Recent work analysing magnesium hydrogenation using Reflecting Electron Energy Loss Spectroscopy(REELS)and Density Function Theory(DFT)has indicated interfacial polarisation and interstitial hydrogen clustering influence the reaction rate.The site availability model has been modified to include interstitial hydrogen clustering within the site availability factor and interface polarisation using interface treatment.The new model,SAM-CV-S,has demonstrated improved modelling of magnesium hydrogenation across wide operating conditions,such as temperatures from 330 to 400℃and pressures up to 40 bar.This wide applicability makes it a robust model that can be used to simulate bed performance in solid-state hydrogen stores.Thus,the site availability factor successfully combines interstitial hydrogen clustering with thermal resistance effects,which are known to strongly influence metal hydride reactor designs at scale.The next phase of the model is to incorporate a predictive hydrogen capacity method into the model.
基金Project(50925417) supported by the National Natural Science Funds for Distinguished Young Scholar of ChinaProject(2010AA065203) supported by the High Technology Research and Development Program of China+2 种基金Project(2010-609) Supported by the Scientific Research Foundation for the Returned Overseas Chinese Scholars,Ministry of Education,ChinaProject(ncet-10-0840) supported by Program for New Century Excellent Talents in UniversityProject(2012FJ1080) supported by Key Projects of Science and Technology of Hunan Province,China
文摘Four different methods,namely mineralogical analysis,three-stage BCR sequential extraction procedure,dynamic leaching test and Hakanson Potential Ecological Risk Index Method were used to access the environmental activity and potential ecological risks of heavy metals in zinc leaching residue.The results demonstrate that the environmental activity of heavy metals declines in the following order：CdZnCuAsPb.Potential ecological risk indices for single heavy metal are CdZnCuAsPb.Cd has serious potential ecological risk to the ecological environment and contributes most to the potential toxicity response indices for various heavy metals in the residue.
文摘A multi-component system has the long fixed maintenance time, so the opportunistic maintenance policy is adopted to put preventive replacement and corrective replacement together, so that the long fixed maintenance time can be shared by more than one component, and the system availability can be improved. Then, the generation characteristics of the random failure time are researched based on the replacement maintenance and the minima[ maintenance. Furthermore, by choosing the opportunistic replacement ages of each component as opti- mized variables, a simulation algorithm based on an opportunistic maintenance policy is designed to maximize the total availability. Finally, the simulation result shows the validity of the algorithm by an example.
基金the grants from the National Natural Science Foundation of China (No. 30471377)the National Key Basic Research Program of China (No. 2007CB106803)the National Key Technologies R & D Program of China (No. 2006BAD26B0201-1)
文摘A laboratory simulated freeze-thaw was conducted to determine the effects of freeze-thaw on soil nutrient availability in temperate semi-arid regions. Soil samples were collected from sandy soils （0-20 cm） of three typical ecosystems （grassland, Mongolian pine plantation and poplar plantation） in southeastern Keerqin Sandy Lands of China and subjected to freeze-thaw treatment （-12℃ for 10 days, then r 20℃ for 10 days） or incubated at constant temperature （20℃ for 20 days）. Concentrations of the soil NO3^--N, NH4^＋-N, NaHCO3 extractable inorganic P （LPi） and microbial biomass P （MBP） were determined on three occasions： at the start of the incubation, immediate post-thawing and at the 10th day post-thawing. The results showed that soil net nitrification and N mineralization rates at three sites were negatively affected by freeze-thaw treatment, and decreased by 50%-85% as compared to the control, of which the greatest decline occurred in the soil collected from poplar plantation. In contrast, the concentration of soil NH4^＋-N, NaHCO3 extractable inorganic P （LPi） and microbial biomass P were insignificantly influenced by freeze-thaw except that LPi and NH4^＋-N showed a slight increase immediate post-thawing. The effects of freeze-thaw on soil N transformation were related to soil biological processes and the relatively constant available P was ascribed to severe soil aridity.
基金Supported by a Sub-project "Ecological Geochemical Survey of Oil Crop (sunflower) Producing Area in Western Jilin" of the Project of China Geological Survey and Jilin Provincial Government " Agricul-tural Geological Survey of Jilin Province"~~
文摘Based on the assay of the total content and available content of the trace nutrient elements and the soil pH and organic matter of the soil samples,the characteristic of the available content of the trace nutrient elements and their affecting factors are studied. The results show that the available B in western Jilin is in a middle level,the content in Nong'an is higher than that in the others; the available Mn is extremely abundant; the available Cu in Nong'an is obviously higher than other areas,and the content in Da'an differs greatly; the available Zn is in a middle level; the severe shortage of available Mo differs between different areas; and the available Fe is extremely abundant. The available Mn,Cu and Fe have significantly positive correlation with their total content; the available B has significantly positive correlation with pH,and Zn has obviously negative correlation with pH; the available Mn and Fe had significantly positive correlation with soil organic matter.
基金The National High Technology Research and Development Program of China (863Program)(No2006AA01Z268)
文摘To cope with the problem of low protocol efficiency of the standard ad hoc on-demand distance vector （AODV） routing protocol with the periodic Hello message broadcast mechanism, a new link availability prediction based strategy is introduced to reduce the amount of Hello messages. In this strategy, a novel wireless link availability prediction model under line-of-sight （LOS） propagation environments is proposed based on which the parameter of Hello Interval in AODV can be dynamically adjusted to achieve the goal of changing the frequency of Hello message broadcasts under different link stability degrees. Simulation results demonstrate that, compared with the standard AODV with the periodic Hello message broadcast mechanism, the proposed protocol effectively reduces unnecessary control message overhead and greatly improves the performance in terms of end-to-end delay and efficiency.
基金Supported by Scientific Research Project of Education Department of Zhejiang Province(Y201328325)Public Welfare Project of Lishui City(2012JYZB47)+1 种基金Project for Highlevel Talents of Lishui City(2014RC04)Project for the Transformation of Agricultural Scientific and Technological Achievements(2012NZH0205)~~
文摘Through indoor culture experiments, the effects of continuous irrigation of biogas slurry on the forms and biological availability of Pb in soil of a tea garden were studied. The results show that continuous irrigation of biogas slurry could change the forms of Pb in the soil, and exchangeable Pb, Pb bonded to iron and manganese oxides, and Pb bonded to carbonates transformed to Pb bonded to or- ganic matter and residual Pb in the soil. Among various forms of Pb in the soil, the content of residual Pb was the highest in the soil irrigated with biogas slurry contin- uously in various treatments, accounting for 54.56%, 60.00% and 60.70% in the treatments T1, T2 and T3 respectively. Compared with the CK, the application of bio- gas slurry could decrease the biological activity and biological availability of Pb in the soil obviously, and the reduction of the biological activity was 21.26%-22.83%. In a word, the application of biogas slurry in soil of the tea garden could inhibit the biological activity and biological availability of Pb.
