With the rapid development of new quality productivity and the in-depth advancement of digital transformation,vocational college libraries,as important supporting institutions for teaching and research,are facing the ...With the rapid development of new quality productivity and the in-depth advancement of digital transformation,vocational college libraries,as important supporting institutions for teaching and research,are facing the dual challenges of service model transformation and capacity improvement.Based on the changes in the demand for digital academic services under the background of new quality productivity,this paper systematically analyzes the current situation and problems of the digital academic service capabilities of librarians in vocational colleges,constructs a capability model including four dimensions:cognitive attitude,knowledge reserve,skill application,and communication and sharing,and proposes capability improvement strategies from aspects such as organizational incentives,professional training,service innovation,and technical support.Research shows that librarians in vocational colleges need to comprehensively enhance their digital academic service capabilities through paths such as concept renewal,skill strengthening,service transformation,and environment optimization,in order to adapt to the demands of educational reform in the era of new quality productivity.展开更多
In this work,we have developed a lignin-derived polymer electrolyte(LSELi),which demonstrates exceptional ionic conductivity of 1.6×10^(-3)S cm^(−1)and a high cation transference number of 0.57 at 25°C.Time ...In this work,we have developed a lignin-derived polymer electrolyte(LSELi),which demonstrates exceptional ionic conductivity of 1.6×10^(-3)S cm^(−1)and a high cation transference number of 0.57 at 25°C.Time of flight secondary ion mass spectrometry(TOF-SIMS)analysis shows that the large-size 1-ethyl-3-methylimidazolium cations(EMIM^(+))can induce the aggregation of the anionic segments in lignosulfonate to reconstruct the three-dimensional(3D)spatial structure of polyelectrolyte,thereby forming a fluent Li^(+)transport 3D network.Dielectric loss spectroscopy further reveals that within this transport network,Li^(+)transport is decoupled from the relaxation of lignosulfonate chain segments,exhibiting characteristics of rapid Li^(+)transport.Furthermore,in-situ distribution of relaxation times analysis indicates that a stable solid electrolyte interface layer is formed at the Li plating interface with LSELi,optimizing the Li plating interface and exhibiting low charge transfer impedance and stable Li plating and stripping.Thus,a substantially prolonged cycling stability and reversibility are obtained in the Li||LSELi||Li battery at 25°C(1800 h at 0.1 mA cm^(−2),0.1 mAh cm^(−2)).At 25°C,the Li||LSELi||LiFePO_(4)cell shows 132 mAh g^(−1)of capacity with 92.7%of retention over 120 cycles at 0.1 mA cm^(−2).展开更多
Fractional optical vortices in the terahertz(THz)regime are supposed to have unique applications in various areas,i.e.,THz communications,optical manipulations,and THz imaging.However,it is still challenging to genera...Fractional optical vortices in the terahertz(THz)regime are supposed to have unique applications in various areas,i.e.,THz communications,optical manipulations,and THz imaging.However,it is still challenging to generate and manipulate high-power THz vortices.Here,we present a way to generate intense THz vortex beams with a continuously tunable topological charge by injecting a weakly relativistic ultrashort laser pulse into a parabolic plasma channel.By adjusting the injection conditions of the laser pulse,the trajectory of the laser centroid can be twisted into a cylindrical spiral,along which laser wakefields are also excited.Due to the inhomogeneous transverse density profile of the plasma channel and laser wakefield excitation,intense THz radiation carrying orbital angular momentum is produced with field strength reaching sub-GV/m,even though the drive laser energy is at a few tens of mJ.The topological charge of such a radiation is determined by the laser trajectories,which are continuously tunable as demonstrated by theoretical analysis as well as three-dimensional particle-in-cell simulations.Such THz vortices with unique properties may find applications in broad areas.展开更多
Ultrasensitive nanomechanical instruments,e.g.atomic force microscopy(AFM),can be used to perform delicate biomechanical measurements and reveal the complex mechanical environment of biological processes.However,these...Ultrasensitive nanomechanical instruments,e.g.atomic force microscopy(AFM),can be used to perform delicate biomechanical measurements and reveal the complex mechanical environment of biological processes.However,these instruments are limited because of their size and complex feedback system.In this study,we demonstrate a miniature fiber optical nanomechanical probe(FONP)that can be used to detect the mechanical properties of single cells and in vivo tissue measurements.A FONP that can operate in air and in liquids was developed by programming a microcantilever probe on the end face of a single-mode fiber using femtosecond laser two-photon polymerization nanolithography.To realize stiffness matching of the FONP and sample,a strategy of customizing the microcantilever’s spring constant according to the sample was proposed based on structure-correlated mechanics.As a proof-of concept,three FONPs with spring constants varying from 0.421 N m^(−1)to 52.6 N m^(−1)by more than two orders of magnitude were prepared.The highest microforce sensitivity was 54.5 nmμN^(−1)and the detection limit was 2.1 nN.The Young’s modulus of heterogeneous soft materials,such as polydimethylsiloxane,muscle tissue of living mice,onion cells,and MCF-7 cells,were successfully measured,which validating the broad applicability of this method.Our strategy provides a universal protocol for directly programming fiber-optic AFMs.Moreover,this method has no special requirements for the size and shape of living biological samples,which is infeasible when using commercial AFMs.FONP has made substantial progress in realizing basic biological discoveries,which may create new biomedical applications that cannot be realized by current AFMs.展开更多
The CO_2 sensing of PrFeO_3 and NdFeO_3 sensors were investigated. Experimental results show that the resistances for PrFeO_3 and NdFeO_3 in CO_2 gas are larger than those in air and the responses for PrFeO_3and NdFeO...The CO_2 sensing of PrFeO_3 and NdFeO_3 sensors were investigated. Experimental results show that the resistances for PrFeO_3 and NdFeO_3 in CO_2 gas are larger than those in air and the responses for PrFeO_3and NdFeO_3 sensors increase with an increase in room-temperature relative humidity. When exposed to1000 ppm CO_2, the response of PrFeO_3 thick film based on nano-powders annealed at 700℃can reach8.44 at 160℃for the background of wet air with 58%of room-temperature relative humidity (RH),which is much larger than the corresponding value (3.03) in wet air with 25%RH. The sensing response S of NdFeO_3 thick-film sensor based on nano-powders annealed at 600℃to 3000 ppm CO_2 at the operating temperature 200℃can reach 2.36 for the background of wet air with 72%RH, which is larger than the corresponding value (1.83) in the air with 25%RH. Compared with other CO_2 sensing materials, the PrFeO_3 sensor has larger response at lower operating temperature for CO_2 gas and may be used as a new CO_2 sensing material.展开更多
In this article, we study the Volterra integral equations with two kinds of delay that are proportional delay and nonproportional delay. We mainly use Chebyshev spectral collocation method to analyze them. First, we u...In this article, we study the Volterra integral equations with two kinds of delay that are proportional delay and nonproportional delay. We mainly use Chebyshev spectral collocation method to analyze them. First, we use variable transformation to transform the equation into an new equation which is defined in [-1,1]. Then, with the help of Gronwall inequality and some other lemmas, we provide a rigorous error analysis for the proposed method, which shows that the numerical error decay exponentially in L~∞ and L_(ω~c)~2-norm. In the end, we give numerical test to confirm the conclusion.展开更多
Superconvergence has been studied for long, and many different numerical methods have been analyzed. This paper is concerned with the problem of superconvergence for a two-dimensional time-dependent linear Schr?dinger...Superconvergence has been studied for long, and many different numerical methods have been analyzed. This paper is concerned with the problem of superconvergence for a two-dimensional time-dependent linear Schr?dinger equation with the finite element method. The error estimate and superconvergence property with order O(hk+1)in the H1norm are given by using the elliptic projection operator in the semi-discrete scheme. The global superconvergence is derived by the interpolation post-processing technique. The superconvergence result with order O(hk+1+ τ2) in the H1norm can be obtained in the Crank-Nicolson fully discrete scheme.展开更多
In this paper,two-grid immersed finite element (IFE) algorithms are proposed and analyzed for semi-linear interface problems with discontinuous diffusion coefficients in two dimension.Because of the advantages of fini...In this paper,two-grid immersed finite element (IFE) algorithms are proposed and analyzed for semi-linear interface problems with discontinuous diffusion coefficients in two dimension.Because of the advantages of finite element (FE) formulation and the simple structure of Cartesian grids,the IFE discretization is used in this paper.Two-grid schemes are formulated to linearize the FE equations.It is theoretically and numerically illustrated that the coarse space can be selected as coarse as H =O(h^1/4)(or H =O(h^1/8)),and the asymptotically optimal approximation can be achieved as the nonlinear schemes.As a result,we can settle a great majority of nonlinear equations as easy as linearized problems.In order to estimate the present two-grid algorithms,we derive the optimal error estimates of the IFE solution in the L^p norm.Numerical experiments are given to verify the theorems and indicate that the present two-grid algorithms can greatly improve the computing efficiency.展开更多
Let b^→=（b1,…,bm）,bi∈∧°βi（R^n）,1≤i≤m,0〈βi〈β,0〈β〈1,[B^→,T]f（x）=∫R^n（b1（x）-b1（y））…（bm（x）-bm（y））K（x-y）f（y）dy,where K is a Calder6n-Zygmund kernel. In this paper, we show that ...Let b^→=（b1,…,bm）,bi∈∧°βi（R^n）,1≤i≤m,0〈βi〈β,0〈β〈1,[B^→,T]f（x）=∫R^n（b1（x）-b1（y））…（bm（x）-bm（y））K（x-y）f（y）dy,where K is a Calder6n-Zygmund kernel. In this paper, we show that [b^→,T] is bounded from L^p（R^n） to Fp^β,∞（R^n）,as well as [b^→,1α]form L^p （R^n） to Fp^β,∞（R^n）,where 1/q=1/p-α/n.展开更多
LaMnO_(3) modified Co_(3)O_(4) nanocomposites were prepared by simple hydrothermal method co mbined with sol-gel method.The gas sensitivity properties of pure Co_(3)O_(4) and LaMnO_(3)/Co_(3)O_(4) with different compo...LaMnO_(3) modified Co_(3)O_(4) nanocomposites were prepared by simple hydrothermal method co mbined with sol-gel method.The gas sensitivity properties of pure Co_(3)O_(4) and LaMnO_(3)/Co_(3)O_(4) with different composite proportions are compared.It is found that 0.6-LMO/Co_(3)O_(4) sensor has higher sensitivity to triethylamine(TEA)than pure Co_(3)O_(4) sensor,which is improved by 9.27 times.And the working temperature is reduced from 150 to 130℃.Besides,it has excellent gas selectivity and repeatability.The improvement of the gas sensitivity of LaMnO_(3)/Co_(3)O_(4) sensor may be due to the fact that LaMnO_(3) is an effective catalyst,and the catalytic performance perhaps is beneficial to improving the sensing performance.In addition,the formation of p-p heterojunctions may be the key factor to improve the gas sensing performance.This work provides a new Co_(3)O_(4)-based gas sensing material for the detection of TEA.展开更多
In this paper,we present a smoothing Newton-like method for solving nonlinear systems of equalities and inequalities.By using the so-called max function,we transfer the inequalities into a system of semismooth equalit...In this paper,we present a smoothing Newton-like method for solving nonlinear systems of equalities and inequalities.By using the so-called max function,we transfer the inequalities into a system of semismooth equalities.Then a smoothing Newton-like method is proposed for solving the reformulated system,which only needs to solve one system of linear equations and to perform one line search at each iteration. The global and local quadratic convergence are studied under appropriate assumptions. Numerical examples show that the new approach is effective.展开更多
Endosperm mutants are critical to the studies on both starch synthesis and metabolism and genetic improvement of starch quality in maize.In the present study,a novel maize endosperm mutant A0178 of natural variation w...Endosperm mutants are critical to the studies on both starch synthesis and metabolism and genetic improvement of starch quality in maize.In the present study,a novel maize endosperm mutant A0178 of natural variation was used as the experimental material and identified and then characterized.Through phenotypic identification,genetic analysis,main ingredients measurement and embryo rescue,development of genetic mapping population from A0178,the endosperm mutant gene was located.The results showed that the mutant exhibited extremely low germination ability as attributed to the inhibited embryo development,and amounts of sugars were accumulated in the mutant seeds and more sugars content was detected at 23 days after pollination(DAP)in A0178 than B73.Employing genetic linkage analysis,the mutant trait was mapped in the bin 5.04 on chromosome 5.Sequence analysis showed that two sites of base transversion and insertion presented in the protein coding region and non-coding region of the mutant brittle-1(bt1),the adenylate translocator encoding gene involved in the starch synthesis.The single base insertion in the coding region cause frameshift mutation,early termination and lose of function of Brittle-1(BT1).All results suggested that bt1 is a novel allelic gene and the causal gene of this endosperm mutant,providing insights on the mechanism of endosperm formation in maize.展开更多
Although tropical cyclones play a critical role in global climate changes,their long-term variations in the past are not well documented.In this article,a sediment core from the South Yellow Sea was studied in order t...Although tropical cyclones play a critical role in global climate changes,their long-term variations in the past are not well documented.In this article,a sediment core from the South Yellow Sea was studied in order to reveal the influence of tropical cyclones on depositional processes.Integrating the results of radiocarbon dating and sediment grain-size analysis,we show that the studied sequence was deposited during the Holocene and the sedimentary dynamics were stable and at a relatively low level,with a median grain-size range of 5.3-8.7μm.It is found that coarse particles were likely transported by highly dynamic depositional events.Based on the findings,a record of paleo-tropical cyclones was derived for the Early Holocene,and several intervals with a reduced influence of tropical cyclones were identified.In addition,it reveals a good agreement between the grain-size results and the changes in solar activity,monsoonal intensity,and the El Ni?o-Southern Oscillation.Overall,it can be concluded that the influence of tropical cyclones on the sedimentary evolution of the muddy zone of the South Yellow Sea was substantial during the Early Holocene on centennial timescales,and that solar maxima may control the intensity of tropical cyclones via strengthening the walker circulation over the tropical Pacific.展开更多
Let T be the singular integral operator with variable kernel, T＊ be the adjoint of T and T# be the pseudo-adjoint of T. Let TIT2 be the product of T1 and T2, T1 o T2 be the pseudo product of T1 and T2. In this paper,...Let T be the singular integral operator with variable kernel, T＊ be the adjoint of T and T# be the pseudo-adjoint of T. Let TIT2 be the product of T1 and T2, T1 o T2 be the pseudo product of T1 and T2. In this paper, we establish the boundedness for commutators of these operators and the fractional differentiation operator D^γ on the weighted Morrey spaces.展开更多
Seamounts are ubiquitous topographic units in global oceans,and their influences on local oceanic circulation have attracted great attention in physical oceanography;however,previous efforts were less made in paleocli...Seamounts are ubiquitous topographic units in global oceans,and their influences on local oceanic circulation have attracted great attention in physical oceanography;however,previous efforts were less made in paleoclimatology and paleoceanography.The Caiwei Guyot in the Magellan Seamounts of the western Pacific is a typical seamount,and in this study,we investigate a well-dated sediment core by magnetic properties to reveal the relationship between deep-sea sedimentary processes and global climate changes.The principal results are as follows:(1)the dominant magnetic minerals in the sediments are low-coercivity magnetite in pseudo-single domain range,probably including a biogenic contribution;(2)the variabilities of magnetic parameters can be clustered into two sections at~500 ka,and the differences between the two units are evident in amplitudes and means;(3)changes in the grainsize-dependent magnetic parameters can be well correlated to records of global ice volume and atmospheric CO;in the middle Pleistocene.Based on these results,a close linkage was proposed between deep-sea sedimentary processes in the Caiwei Guyot and global climate changes.This linkage likely involves different roles of biogenic magnetite in the sediments between interglacial and glacial intervals,responding to changes in marine productivity and deep-sea circulation and displaying a major change in the MidBrunhes climate event.Therefore,we proposed that the sedimentary archives at the bottom of the Caiwei Guyot record some key signals of global climate changes,providing a unique window to observe interactions between various environmental systems on glacial-interglacial timescales.展开更多
In this paper,a Jacobi-collocation spectral method is developed for a Volterraintegro-differential equation with delay,which contains a weakly singular kernel.We use a function transformation and a variable transforma...In this paper,a Jacobi-collocation spectral method is developed for a Volterraintegro-differential equation with delay,which contains a weakly singular kernel.We use a function transformation and a variable transformation to change the equation into a new Volterra integral equation defined on the standard interval[-1,1],so that the Jacobi orthogonal polynomial theory can be applied conveniently.In order to obtain high order accuracy for the approximation,the integral term in the resulting equation is approximated by Jacobi spectral quadrature rules.In the end,we provide a rigorous error analysis for the proposed method.The spectral rate of convergence for the proposed method is established in both the L^(∞)-norm and the weighted L^(2)-norm.展开更多
基金China Transportation Education Research Society Educational Science Research Topic“Research on Improving the Quality of Part-time Teachers in Transportation Vocational Colleges under the Background of New Quality Productivity”(JT2024YB245)。
文摘With the rapid development of new quality productivity and the in-depth advancement of digital transformation,vocational college libraries,as important supporting institutions for teaching and research,are facing the dual challenges of service model transformation and capacity improvement.Based on the changes in the demand for digital academic services under the background of new quality productivity,this paper systematically analyzes the current situation and problems of the digital academic service capabilities of librarians in vocational colleges,constructs a capability model including four dimensions:cognitive attitude,knowledge reserve,skill application,and communication and sharing,and proposes capability improvement strategies from aspects such as organizational incentives,professional training,service innovation,and technical support.Research shows that librarians in vocational colleges need to comprehensively enhance their digital academic service capabilities through paths such as concept renewal,skill strengthening,service transformation,and environment optimization,in order to adapt to the demands of educational reform in the era of new quality productivity.
基金support from the National Natural Science Foundation of China(NSFC,22393901,22021001,22272143,22441030)the National Key Research and Development Program(2021YFA1502300)+1 种基金the Fundamental Research Funds for the Central Universities(20720220009)the Natural Science Foundation of Fujian Province,China(Grant No.2024J01213135)。
文摘In this work,we have developed a lignin-derived polymer electrolyte(LSELi),which demonstrates exceptional ionic conductivity of 1.6×10^(-3)S cm^(−1)and a high cation transference number of 0.57 at 25°C.Time of flight secondary ion mass spectrometry(TOF-SIMS)analysis shows that the large-size 1-ethyl-3-methylimidazolium cations(EMIM^(+))can induce the aggregation of the anionic segments in lignosulfonate to reconstruct the three-dimensional(3D)spatial structure of polyelectrolyte,thereby forming a fluent Li^(+)transport 3D network.Dielectric loss spectroscopy further reveals that within this transport network,Li^(+)transport is decoupled from the relaxation of lignosulfonate chain segments,exhibiting characteristics of rapid Li^(+)transport.Furthermore,in-situ distribution of relaxation times analysis indicates that a stable solid electrolyte interface layer is formed at the Li plating interface with LSELi,optimizing the Li plating interface and exhibiting low charge transfer impedance and stable Li plating and stripping.Thus,a substantially prolonged cycling stability and reversibility are obtained in the Li||LSELi||Li battery at 25°C(1800 h at 0.1 mA cm^(−2),0.1 mAh cm^(−2)).At 25°C,the Li||LSELi||LiFePO_(4)cell shows 132 mAh g^(−1)of capacity with 92.7%of retention over 120 cycles at 0.1 mA cm^(−2).
基金upported by the Strategic Priority Research Program of Chinese Academy of Sciences(Grant Nos.XDA25050100 and XDA25010100)the National Natural Science Foundation of China(Grant Nos.12474428,12135009,11991073,and 11991074)the Science and Technology Commission of Shanghai Municipality(Grant Nos.22JC1401900 and 24ZR1436900).
文摘Fractional optical vortices in the terahertz(THz)regime are supposed to have unique applications in various areas,i.e.,THz communications,optical manipulations,and THz imaging.However,it is still challenging to generate and manipulate high-power THz vortices.Here,we present a way to generate intense THz vortex beams with a continuously tunable topological charge by injecting a weakly relativistic ultrashort laser pulse into a parabolic plasma channel.By adjusting the injection conditions of the laser pulse,the trajectory of the laser centroid can be twisted into a cylindrical spiral,along which laser wakefields are also excited.Due to the inhomogeneous transverse density profile of the plasma channel and laser wakefield excitation,intense THz radiation carrying orbital angular momentum is produced with field strength reaching sub-GV/m,even though the drive laser energy is at a few tens of mJ.The topological charge of such a radiation is determined by the laser trajectories,which are continuously tunable as demonstrated by theoretical analysis as well as three-dimensional particle-in-cell simulations.Such THz vortices with unique properties may find applications in broad areas.
基金supported by the National Natural Science Foundation of China(NSFC)(62122057,62075136,62175165)Natural Science Foundation of Guangdong Province(2022B1515120061,2019B1515120042)Science and Technology Innovation Commission of Shenzhen(RCYX20200714114524139,JCYJ20200109114001806).
文摘Ultrasensitive nanomechanical instruments,e.g.atomic force microscopy(AFM),can be used to perform delicate biomechanical measurements and reveal the complex mechanical environment of biological processes.However,these instruments are limited because of their size and complex feedback system.In this study,we demonstrate a miniature fiber optical nanomechanical probe(FONP)that can be used to detect the mechanical properties of single cells and in vivo tissue measurements.A FONP that can operate in air and in liquids was developed by programming a microcantilever probe on the end face of a single-mode fiber using femtosecond laser two-photon polymerization nanolithography.To realize stiffness matching of the FONP and sample,a strategy of customizing the microcantilever’s spring constant according to the sample was proposed based on structure-correlated mechanics.As a proof-of concept,three FONPs with spring constants varying from 0.421 N m^(−1)to 52.6 N m^(−1)by more than two orders of magnitude were prepared.The highest microforce sensitivity was 54.5 nmμN^(−1)and the detection limit was 2.1 nN.The Young’s modulus of heterogeneous soft materials,such as polydimethylsiloxane,muscle tissue of living mice,onion cells,and MCF-7 cells,were successfully measured,which validating the broad applicability of this method.Our strategy provides a universal protocol for directly programming fiber-optic AFMs.Moreover,this method has no special requirements for the size and shape of living biological samples,which is infeasible when using commercial AFMs.FONP has made substantial progress in realizing basic biological discoveries,which may create new biomedical applications that cannot be realized by current AFMs.
基金supported by National Natural Science Foundation of China(51272133,51472145,51772174 and 51472150)Shandong Natural Science Foundation(ZR2016EMM20)
文摘The CO_2 sensing of PrFeO_3 and NdFeO_3 sensors were investigated. Experimental results show that the resistances for PrFeO_3 and NdFeO_3 in CO_2 gas are larger than those in air and the responses for PrFeO_3and NdFeO_3 sensors increase with an increase in room-temperature relative humidity. When exposed to1000 ppm CO_2, the response of PrFeO_3 thick film based on nano-powders annealed at 700℃can reach8.44 at 160℃for the background of wet air with 58%of room-temperature relative humidity (RH),which is much larger than the corresponding value (3.03) in wet air with 25%RH. The sensing response S of NdFeO_3 thick-film sensor based on nano-powders annealed at 600℃to 3000 ppm CO_2 at the operating temperature 200℃can reach 2.36 for the background of wet air with 72%RH, which is larger than the corresponding value (1.83) in the air with 25%RH. Compared with other CO_2 sensing materials, the PrFeO_3 sensor has larger response at lower operating temperature for CO_2 gas and may be used as a new CO_2 sensing material.
基金supported by National Science Foundation of China(11671157,11626074)Hanshan Normal Uninversity projects(LF201404,Z16027)
文摘In this article, we study the Volterra integral equations with two kinds of delay that are proportional delay and nonproportional delay. We mainly use Chebyshev spectral collocation method to analyze them. First, we use variable transformation to transform the equation into an new equation which is defined in [-1,1]. Then, with the help of Gronwall inequality and some other lemmas, we provide a rigorous error analysis for the proposed method, which shows that the numerical error decay exponentially in L~∞ and L_(ω~c)~2-norm. In the end, we give numerical test to confirm the conclusion.
基金supported by the Nursing Research Fund of Weifang Medical University(2022MS001).
文摘目的 旨在建立一个动态在线诺谟图模型并进行验证,以预测老年心力衰竭住院患者的衰弱风险.方法 2021年12月至2022年11月,选取山东省潍坊市1所三级甲等医院心血管内科住院的451例老年心力衰竭患者为研究对象.采用Bartherl指数、工具性日常生活活动能力量表、迷你营养评估简表、匹兹堡睡眠质量指数量表、Morse跌倒评估量表及一般资料量表收集数据,并通过电子病历收集患者的脑钠肽和超声心动图指标.所有数据使用R软件按7:3的比例随机分为训练集(n=319)和验证集(n=132).采用最小绝对收缩和选择算子(Least Absolute Shrinkage and Selection Operator,LASSO)回归方法筛选建模变量,然后使用多变量逻辑回归建立诺谟图.采用受试者工作特征曲线下面积(area under the curve,AUC)、Hosmer-Lemeshow检验、校准图和决策曲线分析(decision curve analysis,DCA)评估模型性能.结果 衰弱的总体发生率为50.6%.在训练集和验证集中,衰弱发生率分别为51.4%和48.5%.LASSO回归结果显示,饮酒、握力、纽约心脏协会心功能分级、多发疾病、心力衰竭住院史、日常生活活动能力、工具性日常生活活动能力、营养状况、睡眠、跌倒风险和左心房舒张末直径为模型纳入变量.诺谟图的AUC为0.920,敏感性为86.8%,特异性为84.4%.H-L检验P值为0.742,DCA表明诺谟图具有良好的临床适用性.结论 在线动态诺谟图适用于预测老年心力衰竭住院患者的衰弱程度,可以帮助医护人员及时诊断衰弱高危人群,以减轻心力衰竭住院负担.
基金Project supported by the National Natural Science Foundation of China(No.11671157)
文摘Superconvergence has been studied for long, and many different numerical methods have been analyzed. This paper is concerned with the problem of superconvergence for a two-dimensional time-dependent linear Schr?dinger equation with the finite element method. The error estimate and superconvergence property with order O(hk+1)in the H1norm are given by using the elliptic projection operator in the semi-discrete scheme. The global superconvergence is derived by the interpolation post-processing technique. The superconvergence result with order O(hk+1+ τ2) in the H1norm can be obtained in the Crank-Nicolson fully discrete scheme.
基金Project supported by the National Natural Science Foundation of China(Nos.11671157 and11826212)
文摘In this paper,two-grid immersed finite element (IFE) algorithms are proposed and analyzed for semi-linear interface problems with discontinuous diffusion coefficients in two dimension.Because of the advantages of finite element (FE) formulation and the simple structure of Cartesian grids,the IFE discretization is used in this paper.Two-grid schemes are formulated to linearize the FE equations.It is theoretically and numerically illustrated that the coarse space can be selected as coarse as H =O(h^1/4)(or H =O(h^1/8)),and the asymptotically optimal approximation can be achieved as the nonlinear schemes.As a result,we can settle a great majority of nonlinear equations as easy as linearized problems.In order to estimate the present two-grid algorithms,we derive the optimal error estimates of the IFE solution in the L^p norm.Numerical experiments are given to verify the theorems and indicate that the present two-grid algorithms can greatly improve the computing efficiency.
基金Supported by NSF of China (Grant: 10571015)NSF of China (Grant: 10371004)RFDP of China (Grant: 20050027025).
文摘Let b^→=（b1,…,bm）,bi∈∧°βi（R^n）,1≤i≤m,0〈βi〈β,0〈β〈1,[B^→,T]f（x）=∫R^n（b1（x）-b1（y））…（bm（x）-bm（y））K（x-y）f（y）dy,where K is a Calder6n-Zygmund kernel. In this paper, we show that [b^→,T] is bounded from L^p（R^n） to Fp^β,∞（R^n）,as well as [b^→,1α]form L^p （R^n） to Fp^β,∞（R^n）,where 1/q=1/p-α/n.
基金Project supported by the Shandong Natural Science Foundation(ZR2019BF030,ZR2019BEM036)。
文摘LaMnO_(3) modified Co_(3)O_(4) nanocomposites were prepared by simple hydrothermal method co mbined with sol-gel method.The gas sensitivity properties of pure Co_(3)O_(4) and LaMnO_(3)/Co_(3)O_(4) with different composite proportions are compared.It is found that 0.6-LMO/Co_(3)O_(4) sensor has higher sensitivity to triethylamine(TEA)than pure Co_(3)O_(4) sensor,which is improved by 9.27 times.And the working temperature is reduced from 150 to 130℃.Besides,it has excellent gas selectivity and repeatability.The improvement of the gas sensitivity of LaMnO_(3)/Co_(3)O_(4) sensor may be due to the fact that LaMnO_(3) is an effective catalyst,and the catalytic performance perhaps is beneficial to improving the sensing performance.In addition,the formation of p-p heterojunctions may be the key factor to improve the gas sensing performance.This work provides a new Co_(3)O_(4)-based gas sensing material for the detection of TEA.
基金supported by Guangdong Provincial Zhujiang Scholar Award Project,National Science Foundation of China(10671163,10871031)the National Basic Research Program under the Grant 2005CB321703Scientific Research Fund of Hunan Provincial Education Department(06A069,06C824)
文摘In this paper,we present a smoothing Newton-like method for solving nonlinear systems of equalities and inequalities.By using the so-called max function,we transfer the inequalities into a system of semismooth equalities.Then a smoothing Newton-like method is proposed for solving the reformulated system,which only needs to solve one system of linear equations and to perform one line search at each iteration. The global and local quadratic convergence are studied under appropriate assumptions. Numerical examples show that the new approach is effective.
基金This work was financially supported in part by grants from National Science and Technology Support Project of China(2016YFD0101205)the Natural Science Foundation of Jiangsu Province,China(BK20160586)+1 种基金National Transgenic Major Project of China(2019ZX08010-004)as well as Six Talent Peaks Project of Jiangsu Province,China(NY-020).
文摘Endosperm mutants are critical to the studies on both starch synthesis and metabolism and genetic improvement of starch quality in maize.In the present study,a novel maize endosperm mutant A0178 of natural variation was used as the experimental material and identified and then characterized.Through phenotypic identification,genetic analysis,main ingredients measurement and embryo rescue,development of genetic mapping population from A0178,the endosperm mutant gene was located.The results showed that the mutant exhibited extremely low germination ability as attributed to the inhibited embryo development,and amounts of sugars were accumulated in the mutant seeds and more sugars content was detected at 23 days after pollination(DAP)in A0178 than B73.Employing genetic linkage analysis,the mutant trait was mapped in the bin 5.04 on chromosome 5.Sequence analysis showed that two sites of base transversion and insertion presented in the protein coding region and non-coding region of the mutant brittle-1(bt1),the adenylate translocator encoding gene involved in the starch synthesis.The single base insertion in the coding region cause frameshift mutation,early termination and lose of function of Brittle-1(BT1).All results suggested that bt1 is a novel allelic gene and the causal gene of this endosperm mutant,providing insights on the mechanism of endosperm formation in maize.
基金supported by the National Key R&D Program of China (No.2018YFE0202401)the National Natural Science Foundation of China (Nos.41602349 and 41976192)the Marine S&T Fund of Shandong Province for Pilot National Laboratory for Marine Science and Technology (Qingdao)(No.2022QNLM050203)
文摘Although tropical cyclones play a critical role in global climate changes,their long-term variations in the past are not well documented.In this article,a sediment core from the South Yellow Sea was studied in order to reveal the influence of tropical cyclones on depositional processes.Integrating the results of radiocarbon dating and sediment grain-size analysis,we show that the studied sequence was deposited during the Holocene and the sedimentary dynamics were stable and at a relatively low level,with a median grain-size range of 5.3-8.7μm.It is found that coarse particles were likely transported by highly dynamic depositional events.Based on the findings,a record of paleo-tropical cyclones was derived for the Early Holocene,and several intervals with a reduced influence of tropical cyclones were identified.In addition,it reveals a good agreement between the grain-size results and the changes in solar activity,monsoonal intensity,and the El Ni?o-Southern Oscillation.Overall,it can be concluded that the influence of tropical cyclones on the sedimentary evolution of the muddy zone of the South Yellow Sea was substantial during the Early Holocene on centennial timescales,and that solar maxima may control the intensity of tropical cyclones via strengthening the walker circulation over the tropical Pacific.
基金supported by NSF of China (Grant No. 11471033)NCET of China (Grant No. NCET-11-0574)the Fundamental Research Funds for the Central Universities (FRF-TP-12-006B)
文摘Let T be the singular integral operator with variable kernel, T＊ be the adjoint of T and T# be the pseudo-adjoint of T. Let TIT2 be the product of T1 and T2, T1 o T2 be the pseudo product of T1 and T2. In this paper, we establish the boundedness for commutators of these operators and the fractional differentiation operator D^γ on the weighted Morrey spaces.
基金The Natural Science Foundation of Shanghai under contract No.19ZR1459800the Key Special Project for Introduced Talents Team of Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou)under contract No.GML2019ZD0106the Project of Global Changing and Air-sea Interaction under contract No.GASI-GEOGE-04
文摘Seamounts are ubiquitous topographic units in global oceans,and their influences on local oceanic circulation have attracted great attention in physical oceanography;however,previous efforts were less made in paleoclimatology and paleoceanography.The Caiwei Guyot in the Magellan Seamounts of the western Pacific is a typical seamount,and in this study,we investigate a well-dated sediment core by magnetic properties to reveal the relationship between deep-sea sedimentary processes and global climate changes.The principal results are as follows:(1)the dominant magnetic minerals in the sediments are low-coercivity magnetite in pseudo-single domain range,probably including a biogenic contribution;(2)the variabilities of magnetic parameters can be clustered into two sections at~500 ka,and the differences between the two units are evident in amplitudes and means;(3)changes in the grainsize-dependent magnetic parameters can be well correlated to records of global ice volume and atmospheric CO;in the middle Pleistocene.Based on these results,a close linkage was proposed between deep-sea sedimentary processes in the Caiwei Guyot and global climate changes.This linkage likely involves different roles of biogenic magnetite in the sediments between interglacial and glacial intervals,responding to changes in marine productivity and deep-sea circulation and displaying a major change in the MidBrunhes climate event.Therefore,we proposed that the sedimentary archives at the bottom of the Caiwei Guyot record some key signals of global climate changes,providing a unique window to observe interactions between various environmental systems on glacial-interglacial timescales.
基金supported by the State Key Program of National Natural Science Foundation of China(11931003)the National Natural Science Foundation of China(41974133,11671157)。
文摘In this paper,a Jacobi-collocation spectral method is developed for a Volterraintegro-differential equation with delay,which contains a weakly singular kernel.We use a function transformation and a variable transformation to change the equation into a new Volterra integral equation defined on the standard interval[-1,1],so that the Jacobi orthogonal polynomial theory can be applied conveniently.In order to obtain high order accuracy for the approximation,the integral term in the resulting equation is approximated by Jacobi spectral quadrature rules.In the end,we provide a rigorous error analysis for the proposed method.The spectral rate of convergence for the proposed method is established in both the L^(∞)-norm and the weighted L^(2)-norm.
