Mass loss caused by glacier calving is one of the direct contributors to global sea level rise.Reliable calving laws are required for accurate modelling of ice sheet mass balance.Both continuous and discontinuous meth...Mass loss caused by glacier calving is one of the direct contributors to global sea level rise.Reliable calving laws are required for accurate modelling of ice sheet mass balance.Both continuous and discontinuous methods have been used for glacial calving simulations.In this study,the discrete element method(DEM)based on dilated polyhedral elements is introduced to simulate the calving process of a tidewater glacier.Dilated polyhedrons can be obtained from the Minkowski sum of a sphere and a core polyhedron.These elements can be utilized to generate a continuum ice material,where the interaction force between adjacent elements is modeled by constructing bonds at the joints of the common faces.A hybrid fracture model considering fracture energy is introduced.The viscous creep behavior of glaciers on long-term scales is not considered.By applying buoyancy and gravity to the modelled glacier,DEM results show that the calving process is caused by cracks which are initialized at the top of the glacier and spread to the bottom.The results demonstrate the feasibility of using the dilated polyhedral DEM method in glacier simulations,additionally allowing the fragment size of the breaking fragments to be counted.The relationship between crack propagation and internal stress in the glacier is analyzed during calving process.Through the analysis of the Mises stress and the normal stress between the elements,it is found that geometric changes caused by the glacier calving lead to the redistribution of the stress.The tensile stress between the elements is the main influencing factor of glacier ice failure.In addition,the element shape,glacier base friction and buoyancy are studied,the results show that the glacier model based on the dilated polyhedral DEM is sensitive to the above conditions.展开更多
The security of cloud data has always been a concern.Cloud server provider may maliciously tamper or delete user’s data for their own benefit,so data integrity audit is of great significance to verify whether data is...The security of cloud data has always been a concern.Cloud server provider may maliciously tamper or delete user’s data for their own benefit,so data integrity audit is of great significance to verify whether data is modified or not.Based on the general three-party audit architecture,a dynamic auditing scheme without bilinear pairings is proposed in this paper.It utilizes exponential operation instead of bilinear mapping to verify the validity of evidence.By establishing the mapping relation between logic index and tag index of data block with index transformation table,our scheme can easily support dynamic data operation.By hiding random numbers in the integrity evidence,our scheme can protect users’privacy information.Detailed security analysis shows that our scheme is secure against attacks such as forgery,replaying and substitution.Further experiments demonstrate that our scheme has lower computational overhead.展开更多
In recent decades,Arctic climate is warming at a rate of almost twice the global average(Osborne et al.,2018).The surface atmosphere and oceanic temperatures over Arctic Ocean increase leads to the rapid retreat of se...In recent decades,Arctic climate is warming at a rate of almost twice the global average(Osborne et al.,2018).The surface atmosphere and oceanic temperatures over Arctic Ocean increase leads to the rapid retreat of sea ice.The extension and thickness of sea ice in the Arctic,as well as the multi-year ice coverage,have decreased significantly.For example,the September sea ice extent in the Arctic,which is the end of the summer melt season,decreases at a rate of larger than 11%per decade(Polyakov et al.,2012).展开更多
Thrombocytopenia caused by Hemolysis, Elevated Liver enzymes and Low Platelet count (HELLP) syndrome in pre-eclampsia parturients can be associated with substantial maternal and neonatal morbidity. Data on the issue o...Thrombocytopenia caused by Hemolysis, Elevated Liver enzymes and Low Platelet count (HELLP) syndrome in pre-eclampsia parturients can be associated with substantial maternal and neonatal morbidity. Data on the issue of the safety of neuraxial anesthesia with thrombocytopenia in HELLP syndrome is limited. A lower limit of 100,000 per microliter for platelet count was suggested as “safe” for performing neuraxial anesthesia, however there is no supporting data. This lower limit is challenged lately. We present a case of uneventful spinal anesthesia for urgent Cesarean section in a patient with severe pre-eclamsia, HELLP syndrome and precipitous platelet drop from 230,000 to 42,000 per microliter.展开更多
This paper presents a new scheme of flaw searching in surface modeling based on Euler Characteristic. This scheme can be applied to surface construction or reconstruction in computer. It is referred to as Euler Accomp...This paper presents a new scheme of flaw searching in surface modeling based on Euler Characteristic. This scheme can be applied to surface construction or reconstruction in computer. It is referred to as Euler Accompanying Test (EAT) algorithm in this paper. Two propositions in algebraic topology are presented, which are the foundation of the EAT algorithm. As the modeling is the first step for rendering in the animation and visualization, or computer-aided design (CAD) in related applications, the flaws can bring some serious problems in the final image or product, such as an artificial sense in animation rendering or a mistaken product in industry. To verify the EAT progressive procedure, a three-dimensional (3D) stamp model is constructed. The modeling process is accompanied by the EAT procedure. The EAT scheme is verified as the flaws in the stamp model are found and modified.展开更多
In recent years,with the increasing planting area of facility tomato,diseases and insect pests such as tomato grey mold(Botrytis cinerea),early blight(Alternaria solani),late blight(Phytophthora infestans),and whitefl...In recent years,with the increasing planting area of facility tomato,diseases and insect pests such as tomato grey mold(Botrytis cinerea),early blight(Alternaria solani),late blight(Phytophthora infestans),and whitefly(Trialeurodes uaporariorum) occur frequently,causing severe harms and difficulties in prevention and control.In order to ensure the normal production of facility tomato and improve the yield and quality of tomato,the corresponding prevention and control measures are put forward according to the regularity of the occurrence of diseases and insect pests and the characteristics of facility environment,which has certain guiding significance for agricultural production.展开更多
Nest site selection is a vital component of bird reproduction success,and an adaptive behavior conducted to decrease nest predation risk with avoiding external disturbances.Understanding patterns of nest site selectio...Nest site selection is a vital component of bird reproduction success,and an adaptive behavior conducted to decrease nest predation risk with avoiding external disturbances.Understanding patterns of nest site selection can provide insights into how species adapt to changes in their habitat and has important conservation implications.In this study,we used microhabitat variables and multi-scale data with a field survey of nest occurrence to determine nest site selection patterns and adaptive strategies of the breeding Oriental Storks(Ciconia boyciana)in different nest areas.Results demonstrate that the nest site microhabitat characteristics of the breeding Oriental Storks significantly differed among the three nesting areas,and nest height was higher in the middle and lower Yangtze River floodplain than in the Northeast China and Bohai Bay nest areas.The food resources and intensity of human disturbance had the greatest effects on the nest site selection of the breeding Oriental Storks.The intensity of human disturbance was positively correlated with the nest height of the breeding Oriental Storks in Bohai Bay and the middle and lower Yangtze River floodplain;however,nest height decreased with the abundance of food resources in the Northeast China nest area.Our findings indicate that the nest site selection patterns of Oriental Storks showed flexible adaptive strategies.In safer environments,nests were lower and closer to food resources,which allows parent storks to invest more in the nestlings.However,in areas where human activity was intense,nests were higher to ensure the safety of their offspring.Some measures that could be taken to improve the breeding habitat of Oriental Storks include increasing the percentage of wetland areas in nesting areas to enhance food resources availability and setting artificial nests at suitable heights in potential nesting grounds to encourage nesting.Finally,the establishment of soft barriers around the nesting areas could increase the safety of nests.展开更多
Tianfu No. 1 is bred from a plant in the population of Sichuan through system selection,which is characterized with early and uniform germination,hypertrophic shoots,full cover with pekoes and long picking period of s...Tianfu No. 1 is bred from a plant in the population of Sichuan through system selection,which is characterized with early and uniform germination,hypertrophic shoots,full cover with pekoes and long picking period of single shoots. Compared with those of Fuding white tea( CK),the fresh leaf yield,tea polyphenols content,free amino acids content,caffeine content and soluble sugar content of Tianfu No. 1 were increased by 8. 89%,6. 98%,10. 00%,2. 96% and31. 58%,respectively. Tianfu No. 1 is a new rare breakthrough tea variety with high development potential,good intrinsic biochemical quality,and strong adaptability for processing multi-typed tea products such as green tea,white tea,black tea and dark tea,etc. It has strong stress resistance and can still grow better in low-humidity areas. In addition,it is not easy to flower and fruit.展开更多
A 41-year Antarctic sea ice concentration(SIC)dataset derived from satellite passive microwave radiometers during the period of 1979–2019 has been used to analyze sea ice changes in recent decades.The trends of SIC a...A 41-year Antarctic sea ice concentration(SIC)dataset derived from satellite passive microwave radiometers during the period of 1979–2019 has been used to analyze sea ice changes in recent decades.The trends of SIC and sea ice extent(SIE)are calculated during the periods of 1979–2019,1979–2013,and 2014–2019.The trends show regionally dependent features.The SIC shows an increasing trend in most of the regions except the Bellingshausen Sea and Amundsen Sea(BA)during 1979–2019 and 1979–2013.The SIE trend shows a decreasing or decelerating trend in the period of 1979–2019((6835±2210)km^(2)/a)compared with the 1979–2013 period((18600±2203)km^(2)/a).In recent years(2014–2019),the SIC and SIE have exhibited decreasing trends(–(34567±3521)km^(2)/month),especially in the Weddell Sea(WS)and Ross Sea(RS)during summer and autumn.The trends are related to regionally dependent causes.The analyses show that the SIC and SIE decreased in response to the warming trend of 2 m air temperature(T_(a-2m))and have exhibited a good relationship with T_(a-2m) in summer and autumn in recent years.The sea ice decrease in the Antarctic is mainly caused by increases in absorbed energy and southward energy transportation in recent years,such as the increase in gained solar radiation and moist static energy from the south,which demonstrate notable regional characteristics.In the WS region,the local positive feedback from the additional absorbed solar radiation,resulting in warmer air and reduced sea ice,is the main reason for the sea ice decrease in recent years.The increase in southward energy transport has also favored a decrease in sea ice.In the RS region,the increase in southward-transported moist static energy has contributed to the decrease in sea ice,and the increases in cloud cover and longwave radiation have prevented sea ice growth.展开更多
Subseasonal Arctic sea ice prediction is highly needed for practical services including icebreakers and commercial ships,while limited by the capability of climate models.A bias correction methodology in this study wa...Subseasonal Arctic sea ice prediction is highly needed for practical services including icebreakers and commercial ships,while limited by the capability of climate models.A bias correction methodology in this study was proposed and performed on raw products from two climate models,the First Institute Oceanography Earth System Model(FIOESM)and the National Centers for Environmental Prediction(NCEP)Climate Forecast System(CFS),to improve 60 days predictions for Arctic sea ice.Both models were initialized on July 1,August 1,and September 1 in 2018.A 60-day forecast was conducted as a part of the official sea ice service,especially for the ninth Chinese National Arctic Research Expedition(CHINARE)and the China Ocean Shipping(Group)Company(COSCO)Northeast Passage voyages during the summer of 2018.The results indicated that raw products from FIOESM underestimated sea ice concentration(SIC)overall,with a mean bias of SIC up to 30%.Bias correction resulted in a 27%improvement in the Root Mean Square Error(RMSE)of SIC and a 10%improvement in the Integrated Ice Edge Error(IIEE)of sea ice edge(SIE).For the CFS,the SIE overestimation in the marginal ice zone was the dominant features of raw products.Bias correction provided a 7%reduction in the RMSE of SIC and a 17%reduction in the IIEE of SIE.In terms of sea ice extent,FIOESM projected a reasonable minimum time and amount in mid-September;however,CFS failed to project both.Additional comparison with subseasonal to seasonal(S2S)models suggested that the bias correction methodology used in this study was more effective when predictions had larger biases.展开更多
Let G =( V,E) be a connected graph and W = { w_1,w_2,…,w_k} be an ordered subset of V( G).For any vertex v ∈V,the locating code of v with respect to W is the k-vector CW( v) = { d( v,w_1),d( v,w_2),…,d( v,w_k) },W ...Let G =( V,E) be a connected graph and W = { w_1,w_2,…,w_k} be an ordered subset of V( G).For any vertex v ∈V,the locating code of v with respect to W is the k-vector CW( v) = { d( v,w_1),d( v,w_2),…,d( v,w_k) },W is said to be a locating set of G if distinct vertices have the distinct locating code,and the locating number of G is defined as: Loc( G) = min{ | W| : W is a locating set of G}.We study the locating set and locating number of a graph G,obtain some bounds for the locating numbers of graphs,and determine the exact value of Loc( G) for some special classes of graphs,such as cycles,wheels,complete t-partite graph and some Cartesian products of paths and cycles. In addition,we also prove that Loc( T) ≥Δ-1 holds for all trees T with maximum degree Δ,and shows a tree T with Loc( T) = Δ-1.展开更多
Background Collimators in the storage ring of high-energy photon source(HEPS)are used to localize the beam loss,making it possible to set local radiation shields.The motion system of the collimator is used to adjust t...Background Collimators in the storage ring of high-energy photon source(HEPS)are used to localize the beam loss,making it possible to set local radiation shields.The motion system of the collimator is used to adjust the position of the movable jaws for controlling the beam loss precisely.Moreover,dump mode of the collimator increases the risk of jaw damage from beam heat deposition.According to the requirements of motion accuracy and the severe working condition of the collimators,a new design of a two-axis motion system for the movable jaws is proposed,realizing high-precision control and extending the lifetime.Purpose The purpose of this paper is to introduce the designing scheme of the motion system for HEPS storage ring horizontal collimators,including the analyses of the key components,the structure design of the motion system and test results of the prototype.Method Temperature excursions of the movable jaw are calculated theoretically and analyzed by ANSYS,respectively.The motion accuracy of the system is measured by coordinate measuring machine.Result The temperature excursion is simulated as 1883 K while using graphite as the absorbing material at dump mode.The motion system consists of a mobile slide for aperture adjustment and a manual wedge jack for vertical adjustment.The average coupled deviation in horizontal direction of the wedge jack is 0.031 mm,while the maximum positioning deviation of the slide is 0.014 mm,both having good repeatability and being compensable.Conclusion Test results of the prototype indicate that the new design of the motion system is applicable to the horizontal collimator in HEPS storage ring.The problem of the jaw rotation in the horizontal movement is found,and the solution is given.展开更多
The gingiva is a key oral barrier that protects oral tissues from various stimuli.A loss of gingival tissue homeostasis causes periodontitis,one of the most prevalent inflammatory diseases in humans.The human gingiva ...The gingiva is a key oral barrier that protects oral tissues from various stimuli.A loss of gingival tissue homeostasis causes periodontitis,one of the most prevalent inflammatory diseases in humans.The human gingiva exists as a complex cell network comprising specialized structures.To understand the tissue-specific pathophysiology of the gingiva,we applied a recently developed spatial enhanced resolution omics-sequencing(Stereo-seq)technique to obtain a spatial transcriptome(ST)atlas of the gingiva in healthy individuals and periodontitis patients.By utilizing Stereo-seq,we identified the major cell types present in the gingiva,which included epithelial cells,fibroblasts,endothelial cells,and immune cells,as well as subgroups of epithelial cells and immune cells.We further observed that inflammation-related signalling pathways,such as the JAK-STAT and NF-κB signalling pathways,were significantly upregulated in the endothelial cells of the gingiva of periodontitis patients compared with those of healthy individuals.Additionally,we characterized the spatial distribution of periodontitis risk genes in the gingiva and found that the expression of IFI16 was significantly increased in endothelial cells of inflamed gingiva.In conclusion,our Stereo-seq findings may facilitate the development of innovative therapeutic strategies for periodontitis by mapping periodontitis-relevant genes and pathways and effector cells.展开更多
Background Sextupoles in the storage ring of HEPS will be adjusted based on beam trajectory.The mechanical design of a beam-based alignment sextupole mover should be developed.The motion accuracy of the mover should b...Background Sextupoles in the storage ring of HEPS will be adjusted based on beam trajectory.The mechanical design of a beam-based alignment sextupole mover should be developed.The motion accuracy of the mover should be better than 5µm under 450 kg load of sextupoles.The movement range is required to be±0.3 mm in both horizontal direction and vertical direction.And the first-order natural frequency of the magnet support system which include movers should be higher than 54 Hz.Purpose The purpose of this paper is to design a mover prototype and to realize its movement performance and equivalent stiffness.And to find the difficulties of development of this mover.Method Interferometer is used to measure the motion accuracy,and pressure accelerometer is used to test the mover equivalent stiffness.Combining with the actual measurement results of equivalent stiffness,the natural frequency of the magnet support system is simulated.Result The motion accuracy reaches to 5.3µm in vertical direction and 1µm in horizontal direction,respectively.The equivalent stiffness of the mover prototype can just able to meet the requirement of frequency of the HEPS magnet support system.Unwanted movement coupling has occurred during the mover exercises in vertical direction.Conclusions Through the research of experimental mover prototype,the methods have been learnt to improve the movement performance and equivalent stiffness of the mover based on sliding friction under high load.However,further researches and improvements are necessary to fix the coupling error during the vertical movement.展开更多
Background Horizontal collimators in the storage ring of high energy photon source(HEPS)are used to localize the majority of the particle loss,making it possible to set local shields.Moreover,movable jaws of the colli...Background Horizontal collimators in the storage ring of high energy photon source(HEPS)are used to localize the majority of the particle loss,making it possible to set local shields.Moreover,movable jaws of the collimators are also designed as beam dumps for the machine protection,to absorb and scatter the mis-steered beam.Because of the compact lattice,each collimator should be installed between the limited space of 240 mm in the beam direction.It is necessary for the collimators to have good thermal dissipation ability to endure the synchrotron radiation and HOM load,as well as good resistance to thermal-shock from sudden beam loss simultaneously,which brings great challenges to the design.Purpose The purpose of this paper is to introduce the designing scheme of the collimators in HEPS,including the structure design and the analyses of the key components.Method Thermal and mechanical calculation has been done,based on which the jaw structure has been optimized.Besides,the modal analysis of the whole magnet-collimator-support assembly has been studied to optimize the shields structure.Result Graphite will be used as the tip for movable jaws in the collimators,which is attached to copper by vacuum brazing.The maximum temperature of the jaw during normal operation is 131°C,while maximum stress of the graphite–copper weld joint is 15.6 MPa.Graphite tip can resist thermal shock caused by whole mis-steered beam.Eigen frequency of the standard assembly is acceptable for HEPS.Conclusion The results of calculations indicate that the present structure can work well for considered operating modes.展开更多
The promise enabled by boron arsenide’s(BAs)high thermal conductivity(κ)in power electronics cannot be assessed without taking into account the reduction incurred when doping the material.Using first principles calc...The promise enabled by boron arsenide’s(BAs)high thermal conductivity(κ)in power electronics cannot be assessed without taking into account the reduction incurred when doping the material.Using first principles calculations,we determine theκreduction induced by different group IV impurities in BAs as a function of concentration and charge state.We unveil a general trend,where neutral impurities scatter phonons more strongly than the charged ones.CB and GeAs impurities show by far the weakest phonon scattering and retain BAsκvalues of over~1000W⋅K^(−1)⋅m^(−1) even at high densities.Both Si and Ge achieve large hole concentrations while maintaining highκ.Furthermore,going beyond the doping compensation threshold associated to Fermi level pinning triggers observable changes in the thermal conductivity.This informs design considerations on the doping of BAs,and it also suggests a direct way to determine the onset of compensation doping in experimental samples.展开更多
Purpose For the High Energy Photon Source(HEPS),a green-field fourth-generation storage ring light source,the prelimi-nary design report(PDR)was completed in 2018,when the accelerator physics design had been basically...Purpose For the High Energy Photon Source(HEPS),a green-field fourth-generation storage ring light source,the prelimi-nary design report(PDR)was completed in 2018,when the accelerator physics design had been basically finished.During the subsequent hardware and engineering design of the HEPS storage ring based on the PDR design,a few problems and challenges emerged,calling for modifications of the lattice.Method In this paper,we will introduce the background and reasons for the modifications and present the linear optics and simulation results for the nonlinear performance of the modified lattice of the HEPS storage ring.Result and conclusion The modified lattice satisfies the requirements from hardware and engineering design.展开更多
Residue networks are constructed by defining the residues as the vertices and atom contacts between them as the edges. The residue network of a protein complex is divided into two types of networks, i.e. the hydrophob...Residue networks are constructed by defining the residues as the vertices and atom contacts between them as the edges. The residue network of a protein complex is divided into two types of networks, i.e. the hydrophobic and the hydrophilic residue networks. By analyzing the network parameters, it is found that the correct binding complex conformations are of both higher sum of the interface degree values and lower characteristic path length than those incorrect ones. These features reflect that the correct bind-ing complex conformations have better geometric and/or residue type complementarity, and the correct binding modes are very important for preserving the characteristic path lengths of native protein complexes. In addition, two scoring terms are proposed based on the network parameters, in which the characteristics of the entire complex shape and residue type complementarity are taken into account. These network-based scoring terms have also been used in conjunction with other scoring terms, and the new multi-term scoring HPNCscore is devised in this work. It can improve the discrimination of the combined scoring function of RosettaDock more than 12%. This work might enhance our knowledge of the mechanisms of protein-protein interactions and recognition.展开更多
基金The National Key R&D Program of China under contract Nos 2018YFA0605902,2016YFC1402705,2016YFC1402706 and 2016YFC1401505the National Natural Science Foundation of China under contract Nos 41576179 and 51639004+1 种基金the fund of Australian Research Council’s Special Research Initiative for Antarctic Gateway Partnership under contract No.SR140300001the China Postdoctoral Science Foundation under contract No.2020M670746.
文摘Mass loss caused by glacier calving is one of the direct contributors to global sea level rise.Reliable calving laws are required for accurate modelling of ice sheet mass balance.Both continuous and discontinuous methods have been used for glacial calving simulations.In this study,the discrete element method(DEM)based on dilated polyhedral elements is introduced to simulate the calving process of a tidewater glacier.Dilated polyhedrons can be obtained from the Minkowski sum of a sphere and a core polyhedron.These elements can be utilized to generate a continuum ice material,where the interaction force between adjacent elements is modeled by constructing bonds at the joints of the common faces.A hybrid fracture model considering fracture energy is introduced.The viscous creep behavior of glaciers on long-term scales is not considered.By applying buoyancy and gravity to the modelled glacier,DEM results show that the calving process is caused by cracks which are initialized at the top of the glacier and spread to the bottom.The results demonstrate the feasibility of using the dilated polyhedral DEM method in glacier simulations,additionally allowing the fragment size of the breaking fragments to be counted.The relationship between crack propagation and internal stress in the glacier is analyzed during calving process.Through the analysis of the Mises stress and the normal stress between the elements,it is found that geometric changes caused by the glacier calving lead to the redistribution of the stress.The tensile stress between the elements is the main influencing factor of glacier ice failure.In addition,the element shape,glacier base friction and buoyancy are studied,the results show that the glacier model based on the dilated polyhedral DEM is sensitive to the above conditions.
基金This work is supported by the National Key R&D Program of China(2016YFB0800402)partially supported by the National Natural Science Foundation of China under Grant No.61232004and the Fundamental Research Funds for the Central Universities(2016YXMS020).
文摘The security of cloud data has always been a concern.Cloud server provider may maliciously tamper or delete user’s data for their own benefit,so data integrity audit is of great significance to verify whether data is modified or not.Based on the general three-party audit architecture,a dynamic auditing scheme without bilinear pairings is proposed in this paper.It utilizes exponential operation instead of bilinear mapping to verify the validity of evidence.By establishing the mapping relation between logic index and tag index of data block with index transformation table,our scheme can easily support dynamic data operation.By hiding random numbers in the integrity evidence,our scheme can protect users’privacy information.Detailed security analysis shows that our scheme is secure against attacks such as forgery,replaying and substitution.Further experiments demonstrate that our scheme has lower computational overhead.
基金The National Key R&D Program of China under contract No.2016YFC1402700
文摘In recent decades,Arctic climate is warming at a rate of almost twice the global average(Osborne et al.,2018).The surface atmosphere and oceanic temperatures over Arctic Ocean increase leads to the rapid retreat of sea ice.The extension and thickness of sea ice in the Arctic,as well as the multi-year ice coverage,have decreased significantly.For example,the September sea ice extent in the Arctic,which is the end of the summer melt season,decreases at a rate of larger than 11%per decade(Polyakov et al.,2012).
文摘Thrombocytopenia caused by Hemolysis, Elevated Liver enzymes and Low Platelet count (HELLP) syndrome in pre-eclampsia parturients can be associated with substantial maternal and neonatal morbidity. Data on the issue of the safety of neuraxial anesthesia with thrombocytopenia in HELLP syndrome is limited. A lower limit of 100,000 per microliter for platelet count was suggested as “safe” for performing neuraxial anesthesia, however there is no supporting data. This lower limit is challenged lately. We present a case of uneventful spinal anesthesia for urgent Cesarean section in a patient with severe pre-eclamsia, HELLP syndrome and precipitous platelet drop from 230,000 to 42,000 per microliter.
文摘This paper presents a new scheme of flaw searching in surface modeling based on Euler Characteristic. This scheme can be applied to surface construction or reconstruction in computer. It is referred to as Euler Accompanying Test (EAT) algorithm in this paper. Two propositions in algebraic topology are presented, which are the foundation of the EAT algorithm. As the modeling is the first step for rendering in the animation and visualization, or computer-aided design (CAD) in related applications, the flaws can bring some serious problems in the final image or product, such as an artificial sense in animation rendering or a mistaken product in industry. To verify the EAT progressive procedure, a three-dimensional (3D) stamp model is constructed. The modeling process is accompanied by the EAT procedure. The EAT scheme is verified as the flaws in the stamp model are found and modified.
文摘In recent years,with the increasing planting area of facility tomato,diseases and insect pests such as tomato grey mold(Botrytis cinerea),early blight(Alternaria solani),late blight(Phytophthora infestans),and whitefly(Trialeurodes uaporariorum) occur frequently,causing severe harms and difficulties in prevention and control.In order to ensure the normal production of facility tomato and improve the yield and quality of tomato,the corresponding prevention and control measures are put forward according to the regularity of the occurrence of diseases and insect pests and the characteristics of facility environment,which has certain guiding significance for agricultural production.
基金supported by the National Natural Science Foundation of China(Grant No.32171530 and 31472020)。
文摘Nest site selection is a vital component of bird reproduction success,and an adaptive behavior conducted to decrease nest predation risk with avoiding external disturbances.Understanding patterns of nest site selection can provide insights into how species adapt to changes in their habitat and has important conservation implications.In this study,we used microhabitat variables and multi-scale data with a field survey of nest occurrence to determine nest site selection patterns and adaptive strategies of the breeding Oriental Storks(Ciconia boyciana)in different nest areas.Results demonstrate that the nest site microhabitat characteristics of the breeding Oriental Storks significantly differed among the three nesting areas,and nest height was higher in the middle and lower Yangtze River floodplain than in the Northeast China and Bohai Bay nest areas.The food resources and intensity of human disturbance had the greatest effects on the nest site selection of the breeding Oriental Storks.The intensity of human disturbance was positively correlated with the nest height of the breeding Oriental Storks in Bohai Bay and the middle and lower Yangtze River floodplain;however,nest height decreased with the abundance of food resources in the Northeast China nest area.Our findings indicate that the nest site selection patterns of Oriental Storks showed flexible adaptive strategies.In safer environments,nests were lower and closer to food resources,which allows parent storks to invest more in the nestlings.However,in areas where human activity was intense,nests were higher to ensure the safety of their offspring.Some measures that could be taken to improve the breeding habitat of Oriental Storks include increasing the percentage of wetland areas in nesting areas to enhance food resources availability and setting artificial nests at suitable heights in potential nesting grounds to encourage nesting.Finally,the establishment of soft barriers around the nesting areas could increase the safety of nests.
基金Supported by Sichuan Financial Public-Welfare Deepened Engineering Research Project(2016GYSH-019)Earmarked Fund for China Agriculture Research System(CARS-19)
文摘Tianfu No. 1 is bred from a plant in the population of Sichuan through system selection,which is characterized with early and uniform germination,hypertrophic shoots,full cover with pekoes and long picking period of single shoots. Compared with those of Fuding white tea( CK),the fresh leaf yield,tea polyphenols content,free amino acids content,caffeine content and soluble sugar content of Tianfu No. 1 were increased by 8. 89%,6. 98%,10. 00%,2. 96% and31. 58%,respectively. Tianfu No. 1 is a new rare breakthrough tea variety with high development potential,good intrinsic biochemical quality,and strong adaptability for processing multi-typed tea products such as green tea,white tea,black tea and dark tea,etc. It has strong stress resistance and can still grow better in low-humidity areas. In addition,it is not easy to flower and fruit.
基金The National Key R&D Program of China under contract Nos 2018YFA0605902 and 2018YFA0605903the National Natural Science Foundation of China under contract Nos 41606218 and 41941009the fund of Chinese National Antarctic Research Expedition logistics support item.
文摘A 41-year Antarctic sea ice concentration(SIC)dataset derived from satellite passive microwave radiometers during the period of 1979–2019 has been used to analyze sea ice changes in recent decades.The trends of SIC and sea ice extent(SIE)are calculated during the periods of 1979–2019,1979–2013,and 2014–2019.The trends show regionally dependent features.The SIC shows an increasing trend in most of the regions except the Bellingshausen Sea and Amundsen Sea(BA)during 1979–2019 and 1979–2013.The SIE trend shows a decreasing or decelerating trend in the period of 1979–2019((6835±2210)km^(2)/a)compared with the 1979–2013 period((18600±2203)km^(2)/a).In recent years(2014–2019),the SIC and SIE have exhibited decreasing trends(–(34567±3521)km^(2)/month),especially in the Weddell Sea(WS)and Ross Sea(RS)during summer and autumn.The trends are related to regionally dependent causes.The analyses show that the SIC and SIE decreased in response to the warming trend of 2 m air temperature(T_(a-2m))and have exhibited a good relationship with T_(a-2m) in summer and autumn in recent years.The sea ice decrease in the Antarctic is mainly caused by increases in absorbed energy and southward energy transportation in recent years,such as the increase in gained solar radiation and moist static energy from the south,which demonstrate notable regional characteristics.In the WS region,the local positive feedback from the additional absorbed solar radiation,resulting in warmer air and reduced sea ice,is the main reason for the sea ice decrease in recent years.The increase in southward energy transport has also favored a decrease in sea ice.In the RS region,the increase in southward-transported moist static energy has contributed to the decrease in sea ice,and the increases in cloud cover and longwave radiation have prevented sea ice growth.
基金The National Key Research and Development Program of China under contract No.2018YFC1407206the National Natural Science Foundation of China under contract Nos 41821004 and U1606405the Basic Scientific Fund for National Public Research Institute of China(Shu Xingbei Young Talent Program)under contract No.2019S06.
文摘Subseasonal Arctic sea ice prediction is highly needed for practical services including icebreakers and commercial ships,while limited by the capability of climate models.A bias correction methodology in this study was proposed and performed on raw products from two climate models,the First Institute Oceanography Earth System Model(FIOESM)and the National Centers for Environmental Prediction(NCEP)Climate Forecast System(CFS),to improve 60 days predictions for Arctic sea ice.Both models were initialized on July 1,August 1,and September 1 in 2018.A 60-day forecast was conducted as a part of the official sea ice service,especially for the ninth Chinese National Arctic Research Expedition(CHINARE)and the China Ocean Shipping(Group)Company(COSCO)Northeast Passage voyages during the summer of 2018.The results indicated that raw products from FIOESM underestimated sea ice concentration(SIC)overall,with a mean bias of SIC up to 30%.Bias correction resulted in a 27%improvement in the Root Mean Square Error(RMSE)of SIC and a 10%improvement in the Integrated Ice Edge Error(IIEE)of sea ice edge(SIE).For the CFS,the SIE overestimation in the marginal ice zone was the dominant features of raw products.Bias correction provided a 7%reduction in the RMSE of SIC and a 17%reduction in the IIEE of SIE.In terms of sea ice extent,FIOESM projected a reasonable minimum time and amount in mid-September;however,CFS failed to project both.Additional comparison with subseasonal to seasonal(S2S)models suggested that the bias correction methodology used in this study was more effective when predictions had larger biases.
基金Sponsored by the National Natural Science Foundation of China(Grant Nos.11361024,61472138)the Provincial Natural Science Foundation(Grant Nos.20171BAB201009,20161BAB202066)the Jiangxi Provincial Science and Technology Project(Grant No.KJLD12067)
文摘Let G =( V,E) be a connected graph and W = { w_1,w_2,…,w_k} be an ordered subset of V( G).For any vertex v ∈V,the locating code of v with respect to W is the k-vector CW( v) = { d( v,w_1),d( v,w_2),…,d( v,w_k) },W is said to be a locating set of G if distinct vertices have the distinct locating code,and the locating number of G is defined as: Loc( G) = min{ | W| : W is a locating set of G}.We study the locating set and locating number of a graph G,obtain some bounds for the locating numbers of graphs,and determine the exact value of Loc( G) for some special classes of graphs,such as cycles,wheels,complete t-partite graph and some Cartesian products of paths and cycles. In addition,we also prove that Loc( T) ≥Δ-1 holds for all trees T with maximum degree Δ,and shows a tree T with Loc( T) = Δ-1.
基金supported by Key Laboratory of Particle Acceleration Physics&Technology,Institute of High Energy Physics,Chinese Academy of Sciences[JSQ2020ZZ05].
文摘Background Collimators in the storage ring of high-energy photon source(HEPS)are used to localize the beam loss,making it possible to set local radiation shields.The motion system of the collimator is used to adjust the position of the movable jaws for controlling the beam loss precisely.Moreover,dump mode of the collimator increases the risk of jaw damage from beam heat deposition.According to the requirements of motion accuracy and the severe working condition of the collimators,a new design of a two-axis motion system for the movable jaws is proposed,realizing high-precision control and extending the lifetime.Purpose The purpose of this paper is to introduce the designing scheme of the motion system for HEPS storage ring horizontal collimators,including the analyses of the key components,the structure design of the motion system and test results of the prototype.Method Temperature excursions of the movable jaw are calculated theoretically and analyzed by ANSYS,respectively.The motion accuracy of the system is measured by coordinate measuring machine.Result The temperature excursion is simulated as 1883 K while using graphite as the absorbing material at dump mode.The motion system consists of a mobile slide for aperture adjustment and a manual wedge jack for vertical adjustment.The average coupled deviation in horizontal direction of the wedge jack is 0.031 mm,while the maximum positioning deviation of the slide is 0.014 mm,both having good repeatability and being compensable.Conclusion Test results of the prototype indicate that the new design of the motion system is applicable to the horizontal collimator in HEPS storage ring.The problem of the jaw rotation in the horizontal movement is found,and the solution is given.
基金supported by the National Natural Science Foundation of China(82201011,82030031,92149301 and 82270945)the Beijing Municipal Government grant(Beijing Laboratory of Oral Health,PXM2021-014226-000041)+2 种基金the Chinese Academy of Medical Sciences Innovation Fund for Medical Sciences(2019-I2M-5-038)the Science and Technology Project of Guangzhou,China(202206080009)the Postdoctoral Foundation of China(2021M703695 and 2021TQ0308)。
文摘The gingiva is a key oral barrier that protects oral tissues from various stimuli.A loss of gingival tissue homeostasis causes periodontitis,one of the most prevalent inflammatory diseases in humans.The human gingiva exists as a complex cell network comprising specialized structures.To understand the tissue-specific pathophysiology of the gingiva,we applied a recently developed spatial enhanced resolution omics-sequencing(Stereo-seq)technique to obtain a spatial transcriptome(ST)atlas of the gingiva in healthy individuals and periodontitis patients.By utilizing Stereo-seq,we identified the major cell types present in the gingiva,which included epithelial cells,fibroblasts,endothelial cells,and immune cells,as well as subgroups of epithelial cells and immune cells.We further observed that inflammation-related signalling pathways,such as the JAK-STAT and NF-κB signalling pathways,were significantly upregulated in the endothelial cells of the gingiva of periodontitis patients compared with those of healthy individuals.Additionally,we characterized the spatial distribution of periodontitis risk genes in the gingiva and found that the expression of IFI16 was significantly increased in endothelial cells of inflamed gingiva.In conclusion,our Stereo-seq findings may facilitate the development of innovative therapeutic strategies for periodontitis by mapping periodontitis-relevant genes and pathways and effector cells.
文摘Background Sextupoles in the storage ring of HEPS will be adjusted based on beam trajectory.The mechanical design of a beam-based alignment sextupole mover should be developed.The motion accuracy of the mover should be better than 5µm under 450 kg load of sextupoles.The movement range is required to be±0.3 mm in both horizontal direction and vertical direction.And the first-order natural frequency of the magnet support system which include movers should be higher than 54 Hz.Purpose The purpose of this paper is to design a mover prototype and to realize its movement performance and equivalent stiffness.And to find the difficulties of development of this mover.Method Interferometer is used to measure the motion accuracy,and pressure accelerometer is used to test the mover equivalent stiffness.Combining with the actual measurement results of equivalent stiffness,the natural frequency of the magnet support system is simulated.Result The motion accuracy reaches to 5.3µm in vertical direction and 1µm in horizontal direction,respectively.The equivalent stiffness of the mover prototype can just able to meet the requirement of frequency of the HEPS magnet support system.Unwanted movement coupling has occurred during the mover exercises in vertical direction.Conclusions Through the research of experimental mover prototype,the methods have been learnt to improve the movement performance and equivalent stiffness of the mover based on sliding friction under high load.However,further researches and improvements are necessary to fix the coupling error during the vertical movement.
基金supported by Key Laboratory of Particle Acceleration Physics&Technology,Institute of High Energy Physics,Chinese Academy of Sciences[JSQ2020ZZ05].
文摘Background Horizontal collimators in the storage ring of high energy photon source(HEPS)are used to localize the majority of the particle loss,making it possible to set local shields.Moreover,movable jaws of the collimators are also designed as beam dumps for the machine protection,to absorb and scatter the mis-steered beam.Because of the compact lattice,each collimator should be installed between the limited space of 240 mm in the beam direction.It is necessary for the collimators to have good thermal dissipation ability to endure the synchrotron radiation and HOM load,as well as good resistance to thermal-shock from sudden beam loss simultaneously,which brings great challenges to the design.Purpose The purpose of this paper is to introduce the designing scheme of the collimators in HEPS,including the structure design and the analyses of the key components.Method Thermal and mechanical calculation has been done,based on which the jaw structure has been optimized.Besides,the modal analysis of the whole magnet-collimator-support assembly has been studied to optimize the shields structure.Result Graphite will be used as the tip for movable jaws in the collimators,which is attached to copper by vacuum brazing.The maximum temperature of the jaw during normal operation is 131°C,while maximum stress of the graphite–copper weld joint is 15.6 MPa.Graphite tip can resist thermal shock caused by whole mis-steered beam.Eigen frequency of the standard assembly is acceptable for HEPS.Conclusion The results of calculations indicate that the present structure can work well for considered operating modes.
基金This work was supported in part by the Office of Naval Research under MURI grant no.N00014-16-1-2436the Agence Nationale de la Recherche through project ANR-17-CE08-0044-01+1 种基金G.K.H.M.acknowledges funding from the Austrian Science Funds(FWF)under project CODIS(Grant no.FWF-I-3576-N36)We thank Nebil Katcho for providing us with the first version of the code used to compute the phonon-defect scattering rates.D.B.thanks Dr.John Lyons of the Naval Research Laboratory for helpful discussions.
文摘The promise enabled by boron arsenide’s(BAs)high thermal conductivity(κ)in power electronics cannot be assessed without taking into account the reduction incurred when doping the material.Using first principles calculations,we determine theκreduction induced by different group IV impurities in BAs as a function of concentration and charge state.We unveil a general trend,where neutral impurities scatter phonons more strongly than the charged ones.CB and GeAs impurities show by far the weakest phonon scattering and retain BAsκvalues of over~1000W⋅K^(−1)⋅m^(−1) even at high densities.Both Si and Ge achieve large hole concentrations while maintaining highκ.Furthermore,going beyond the doping compensation threshold associated to Fermi level pinning triggers observable changes in the thermal conductivity.This informs design considerations on the doping of BAs,and it also suggests a direct way to determine the onset of compensation doping in experimental samples.
基金supported by the High Energy Photon Source(HEPS),a major national science and technol-ogy infrastructurethe National Natural Science Foundation of China(No.11922512)+1 种基金Youth Inno-vation Promotion Association of Chinese Academy of Sciences(No.Y201904)Bureau of Frontier Sciences and Education of Chinese Academy of Sciences(No.QYZDJ-SSW-SLH001)
文摘Purpose For the High Energy Photon Source(HEPS),a green-field fourth-generation storage ring light source,the prelimi-nary design report(PDR)was completed in 2018,when the accelerator physics design had been basically finished.During the subsequent hardware and engineering design of the HEPS storage ring based on the PDR design,a few problems and challenges emerged,calling for modifications of the lattice.Method In this paper,we will introduce the background and reasons for the modifications and present the linear optics and simulation results for the nonlinear performance of the modified lattice of the HEPS storage ring.Result and conclusion The modified lattice satisfies the requirements from hardware and engineering design.
基金supported by the National Natural Science Foundation of China (Grant Nos. 20773006, 30670497, 10974008)Beijing Natural Science Foundation (Grant No. 4102006) Specialized Research Fund for the Doctoral Program of Higher Education (Grant No. 200800050003)
文摘Residue networks are constructed by defining the residues as the vertices and atom contacts between them as the edges. The residue network of a protein complex is divided into two types of networks, i.e. the hydrophobic and the hydrophilic residue networks. By analyzing the network parameters, it is found that the correct binding complex conformations are of both higher sum of the interface degree values and lower characteristic path length than those incorrect ones. These features reflect that the correct bind-ing complex conformations have better geometric and/or residue type complementarity, and the correct binding modes are very important for preserving the characteristic path lengths of native protein complexes. In addition, two scoring terms are proposed based on the network parameters, in which the characteristics of the entire complex shape and residue type complementarity are taken into account. These network-based scoring terms have also been used in conjunction with other scoring terms, and the new multi-term scoring HPNCscore is devised in this work. It can improve the discrimination of the combined scoring function of RosettaDock more than 12%. This work might enhance our knowledge of the mechanisms of protein-protein interactions and recognition.
