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CONVERGENCE OF AN ALtERNAtING A-φ SChEME FOR QUASI-MAGNEtOStAtIC EDDY CURRENt PROBLEM

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Journal of Computational Mathematics 2004年第5期22卷 661-670页

作者： chang-fengMa DepartmentofMathematics HuazhongUniversityofScienceandTechnologyWuhan430074China

We propose in this paper an alternating A-φ method for the quasi-magnetostatic eddy current problem by means of finite element approximations. Bounds for continuous and discrete error in finite time are given. And it is verified that provided the time step τ is sufficiently small, the proposed algorithm yields for finite time t an error of O(h+τ^1/2) in the L^2-norm for the magnetic field h(=μ^-1△↓×A), where h is the mesh size, μ the magnetic permeability.

关键词： Alternating A-φ method Eddy current problem Error estimates Finite element approximation

Succession of aquatic microbial communities as a result of the water quality variations in continuous water

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Journal of Environmental Sciences 2004年第5期16卷 772-778页

作者： WANGRong-chang WENXiang-hua QIANYi EnvironmentStimulationandPollutionControlStateKeyLaboratory DepartmentofEnvironmentalScienceandEngineeringTsinghuaUniversityBeijing100084China

the changes of structural and functional parameters of aquatic microbial communities in continuous water on campus of tsinghua University, China are investigated by polyurethane foam unit(PFU) method. the measured compositions of the communities include alga, protozoa, and some metazoa(such as rotifers). the measured indicators of water quality include water temperature, ph value, dissolved oxygen(DO), potassium permanganate index(COD Mn ), total nitrogen(tN), total phosphorus(tP) and chlorophyll-a(Chla). the trophic level, expressed by the trophic level indices(tLIc), is assessed with analytic hierarchy process and principal component analysis(AhP-PCA) method. the changing trends of the structural and functional parameters of aquatic microbial communities, such as Margalef index of diversity(D), Shannon-weaver index of diversity (h), heterotropy index(hI), number of species when the colonization gets equilibrium(S eq ), colonizing speed constant(G) and time spent when 90 percent of S eq colonized in PFU(t 90% ), are also analyzed. the experimental results showed the succession of aquatic microbial communities along the water flow is consistent with the water quality changes, so the parameters of microbial community can reflect the changes of water quality from the ecological view.

关键词： succession aquatic microbial community polyurethane foam unit(PFU) method water quality biodiversity biomonitoring

Urban Air Pollution May Enhance COVID-19 Case-Fatality and Mortality Rates in the United States

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the Innovation 2020年第3期1卷 114-122页

作者： Donghai Liang Liuhua Shi Jingxuan Zhao Pengfei Liu Jeremy A.Sarnat Song Gao Joel Schwartz Yang Liu Stefanie t.Ebelt Noah Scovronick howard h.chang Gangarosa Department of Environmental health Rollins School of Public HealthEmory University1518 Clifton Road NEAtlantaGA 30322USA Surveillance and health Services Research Program American Cancer SocietyAtlantaGAUSA School of Earth and Atmospheric Sciences Georgia Institute of TechnologyAtlantaGAUSA GeoDS Lab Department of GeographyUniversity of Wisconsin-MadisonMadisonWIUSA Department of Environmental health Harvard T.H.Chan School of Public HealthBostonMAUSA Department of Biostatistics and Bioinformatics Rollins School of Public HealthEmory UniversityAtlantaGAUSA

BACKGROUND the novel human coronavirus disease 2019(COVID-19)pandemic has claimed more than 600,000 lives worldwide,causing tremendous public health,social,and economic *** the risk factors of COVID-19 are still under investigation,environmental factors,such as urban air pollution,may play an important role in increasing population susceptibility to COVID-19 *** We conducted a cross-sectional nationwide study using zero-inflated negative binomial models to estimate the association between longterm(2010–2016)county-level exposures to NO2,PM2.5,and O3 and county-level COVID-19 case-fatality and mortality rates in the United *** used both single-and multi-pollutant models and controlled for spatial trends and a comprehensive set of potential confounders,including state-level test positive rate,county-level health care capacity,phase of epidemic,population mobility,population density,sociodemographics,socioeconomic status,race and ethnicity,behavioral risk factors,and *** From January 22,2020,to July 17,2020,3,659,828 COVID-19 cases and 138,552 deaths were reported in 3,076 US counties,with an overall observed case-fatality rate of 3.8%.County-level average NO2 concentrations were positively associated with both COVID-19 case-fatality rate and mortality rate in single-,bi-,and tri-pollutant *** adjusted for co-pollutants,per interquartile-range(IQR)increase in NO2(4.6 ppb),COVID-19 case-fatality rate and mortality rate were associated with an increase of 11.3%(95%CI 4.9%–18.2%)and 16.2%(95%CI 8.7%–24.0%),*** did not observe significant associations between COVID-19 case-fatality rate and long-term exposure to PM2.5 or O3,although per IQR increase in PM2.5(2.6 mg/m3)was marginally associated,with a 14.9%(95%CI 0.0%–31.9%)increase in COVID-19 mortality rate when adjusted for *** Long-term exposure to NO2,which largely arises from urban combustion sources such as traffic,may enhanc

关键词： AIR POLLUtION NItROGEN DIOXIDE COVID-19 CASEFAtALItY RAtE MORtALItY

CONVERGENCE OF A CONSERVAtIVE DIFFERENCE SChEME FOR thE ZAKhAROV EQUAtIONS IN tWO DIMENSIONS

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Journal of Computational Mathematics 1997年第3期15卷 219-232页

作者： Guo, BL chang, QS INSt APPL PhYS & COMPUtAt MAth BEIJING 100088PEOPLES R CHINA ChINESE ACAD SCI INST APPL MATHBEIJINGPEOPLES R CHINA

A conservative difference scheme is presented for the initial-boundary-value problem of a generalized Zakharov equations. On the basis of a prior estimates in L-2 norm, the convergence of the difference solution is proved in order O(h(2) + r(2)). In the proof, a new skill is used to deal with the term of difference quotient (e(j,k)(n))t. this is necessary, since there is no estimate of E(x, y, t) in L-infinity norm.

关键词： Math CONVERGENCE OF A CONSERVAtIVE DIFFERENCE SChEME FOR thE ZAKhAROV EQUAtIONS IN tWO DIMENSIONS

应用微束质子激发X荧光分析研究Ca和S在头发中的分布模式

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科学通报 2007年第9期52卷 1003-1006页

作者：童永彭 chang Ming Li John h.t.Luong 深圳大学核技术应用联合研究所 School of Chemical and Biomedical Engineering Nanyang Technological Uni-versitySingapore 639798 Biotechnology Research Institute National Research Council CanadaMontrealQuebecCanada H4P 2R2.

应用微束质子激发X荧光分析研究了20余根来自几个成年中国人头发中的Ca和S的分布模式.成年女性头发S含量沿生长方向呈月周期的变化,而Ca含量在男女性生长期头发的中间层均明显偏高且呈现出昼夜周期.Ca的含量在脱落头发中从末梢到根部是... 详细信息

应用微束质子激发X荧光分析研究了20余根来自几个成年中国人头发中的Ca和S的分布模式.成年女性头发S含量沿生长方向呈月周期的变化,而Ca含量在男女性生长期头发的中间层均明显偏高且呈现出昼夜周期.Ca的含量在脱落头发中从末梢到根部是逐渐降低的,而且黑头发中的Ca含量显著高于白头发中.

关键词：激发X荧光分析 Ca S 头发

IMPAIRED ANGIOGENESIS FOLLOWING hIND-LIMB ISChEMIA IN DIABEtES MELLItUS MICE

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Chinese Medical Sciences Journal 2007年第4期22卷 232-237页

作者： Yong-jun Li heng Guan Surovi hazarika chang-wei Liu Brain h Annex Department of Vascular Surgery Peking Union Medical College Hospital Chinese Academy of Medical Sciences ＆ Peking Union Medical College Beijing 100730 Division of Cardiology Department of Medicine Durham VA and Duke University Medical Center Durham North Carolina 27710 USA

Objective to investigate vascular endothelial growth factor(VEGF) and its signaling pathway spontaneous response in type 2 diabetes mellitus(t2DM) mice to surgery-induced hind-limb *** Sixty mice were randomly divided into two groups,one was fed with normal chow as control,and another was fed with high fat diet to induce *** weeks later,mice were surgically induced to hind-limb *** flow restoration was monitored with laser Doppler perfusion *** anterior muscle was collected after 3 days of hind-limb *** mRNA and protein expressions were analyzed using real-time PCR and ELISA;expressions of VEGF downstream signal molecules and receptors were analyzed using Western blotting and Rt-PCR,*** Perfusion recovery 10,20,30 days after ischemia was significantly attenuated in t2DM compared with control group(Pt2DM impaired VEGF signaling pathway although VEGF levels increased in t2DM *** ischemia,t2DM group had a comparable increase in VEGF expression compared with control group,but still had an impaired VEGF signaling *** VEGF signaling pathway is abnormal in t2DM mice,although VEGF had a response to the ischemic stimulation.

关键词： vascular disease diabetes mellitus angiogenesis vascular endothelial growth factor

Efficacy of gecko polysaccharide on suppressed immune response induced by cyclophosphamide in mice

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Journal of traditional Chinese Medicine 2021年第4期41卷 539-545页

作者： ZhOU Xingqin chang Yazhou JI Bin ZhAO hongyu ShEN Chaoyan chang Renan Department of Radiotherapy Affiliated Hospital of Nantong UniversityNangtong 226001China School of Medicine Southeast UniversityNanjing 210009China Department of Radiotherapy Affiliated Hospital of Nantong University20 Xisi roadNangtongJiangsu Province 226001China

OBJECtIVE:to evaluate the efficacy of gecko polysaccharide on the cyclophosphamide-induced suppressed immune response in ***:Polysaccharides were extracted from fresh gecko for the first time using an orthogonal method and protein was removed using Sevag reagent(chloroform∶N-butanol,5∶1,v/v).the gecko polysaccharide(GPCE)content was determined by the phenol-concentrated sulfuric acid *** immunocompromised mouse model was established by intraperitoneally injecting cyclophosphamide at 100 mg/kg into 48 *** effects of GPCE on immune regulation in mice were assessed by a thymus-spleen index,serum hemolysin levels,and the proliferation of splenic *** cell CD4+,CD8+,and the CD4+/CD8+ ratio were evaluated by flow cytometry and the tumor necrosis factor-α(tNF-α)levels were measured by ***:the optimal extraction process for gecko polysaccharide included a 1∶20 ratio of material to liquid(v/v),an extraction temperature of 60℃ and a time of 2 *** polysaccharide content of the extract was 65.74%.GPCE was analyzed by hPLC and primarily contained glucose and small amounts of mannose,rha,and *** with the model,the thymus index,the spleen index were indices for GPCE increased with dose,whereas the high and medium groups exhibited significant differences(Phigher doses of GPCE increased serum tNF-αlevels and there was a significant difference between the medium and high GPCE doses and the model(Pthe number of CD4+ cells and the CD4+/CD8+ ratio in the gecko polysaccharide group were increased(Pthere was no statistical difference in the number of CD8+ cells in the gecko polysaccharide group(P>0.05);the high GPCE dose significantly increased the level of serum hemolysin(Pharide significantly improved the suppressed immune response induced by cyclophosphamide in mice and promoted the secretion of tumor necrosis *** mechanism of gecko polysaccharide as an a

关键词： lizards polysaccharides cyclophosphamide tumor necrosis factor-alpha immune function

Laguerre calculus and Paneitz operator on the heisenberg group

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Science China Mathematics 2009年第12期52卷 2549-2569页

作者： chang Der-Chen Department of Mathematics Georgetown University

Laguerre calculus is a powerful tool for harmonic analysis on the heisenberg group. Many sub-elliptic partial differential operators can be inverted by Laguerre calculus. In this article, we use Laguerre calculus to find explicit kernels of the fundamental solution for the Paneitz operator and its heat equation. the Paneitz operator which plays an important role in CR geometry can be written as follows: $$ {\mathcal{P}_\alpha} = {\mathcal{L}_\alpha} \bar {\mathcal{L}_\alpha} = \fract t\left[ {\sum\limits_{j = 1}^n {\left( {Z_j \bar Z_j + \bar Z_j Z_j } \right)} } \right]^2 + \alpha ^2 t^2 $$ here “Z j ” j=1 n is an orthonormal basis for the subbundle t (1,0) of the complex tangent bundle t ?(h n ) and t is the “missing direction”. the operator $ \mathcal{L}_\alpha $ is the sub-Laplacian on the heisenberg group which is sub-elliptic if α does not belong to an exceptional set Λ α . We also construct projection operators and relative fundamental solution for the operator $ \mathcal{L}_\alpha $ while α ∈ Λ α .

关键词： Paneitz operator heisenberg group Laguerre calculus fundamental solution heat kernel spectrum 35h20 53C44

PREDICtION OF FLOW StRESS OF hIGh-SPEED StEEL DURING hOt DEFORMAtION BY USING BP ARtIFICIAL NEURAL NEtWORK

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Acta Metallurgica Sinica(English Letters) 2000年第1期13卷 394-400页

作者： J. t. Liu h.B. chang R.h. Wu t. Y. hsu(Xu Zuyao) and X.R. Ruan( 1)Department of Plasticity technology, Shanghai Jiao tong University, Shanghai 200030, China 2)School of Materials Science and Engineering, Shanghai Jiao tong University, Shanghai 200030,

the hot deformation behavior of tI (18W-4Cr-1V) high-speed steel was investigated by means of continuous compression tests performed on Gleeble 1500 thermomechan- ical simulator in a wide range of tempemtures (950℃-1150℃) with strain rotes of 0.001s-1-10s-1 and true strains of 0-0. 7. the flow stress at the above hot defor- mation conditions is predicted by using BP artificial neural network. the architecture of network includes there are three input parameters:strain rate,temperature t and true strain , and just one output parameter, the flow stress ,2 hidden layers are adopted, the first hidden layer includes 9 neurons and second 10 negroes. It has been verified that BP artificial neural network with 3-9-10-1 architecture can predict flow stress of high-speed steel during hot deformation very well. Compared with the prediction method of flow stress by using Zaped-holloman parumeter and hyperbolic sine stress function, the prediction method by using BP artificial neurul network has higher efficiency and accuracy.

关键词： t1 high-speed steel flow stress prediction of flow stress back propagation (BP) artificial neural network (ANN)