Because of the difficulty to obtain the traffic flow information of lanes at non-detector intersections in most metropolises of the world,based on the relationships between the lanes of signal-controlled intersections...Because of the difficulty to obtain the traffic flow information of lanes at non-detector intersections in most metropolises of the world,based on the relationships between the lanes of signal-controlled intersections,cluster analysis and stepwise regression are integrated to predict the traffic volume of lanes at non-detector isolated controlled intersections.First cluster analysis is used to cluster the lanes of non-detector isolated signal-controlled intersections and the lanes of all signal-controlled intersections with detectors.Then, by the results of cluster analysis,the traffic volume samples are selected randomly and stepwise regression is used to predict the traffic volume of lanes at non-detector isolated signal-controlled intersections.The method is tested by the traffic volume data of lanes of the road network of Nanjing city.The problem of predicting the traffic volume of lanes at non-detector isolated signal-controlled intersections was resolved and can be widely used in urban traffic flow guidance and urban traffic control in cities without enough intersections equipped with detectors.展开更多
[Objective] The research aimed to study the significant influence factors of the population variations of oriental fruit fly. [Method] Using stepwise regression analysis, the population variations law of oriental frui...[Objective] The research aimed to study the significant influence factors of the population variations of oriental fruit fly. [Method] Using stepwise regression analysis, the population variations law of oriental fruit fly in Jianshui County of Yunnan province and the meteorological factors that caused its occurrence were analyzed. And the regression model was built. Finally, the regression model was tested on the basis of the data in Jianshui County of Yunnan Province during 2004-2006.[Result] The main meteorological factors that influenced the occurrence of oriental fruit fly were relative humidity, the lowest monthly temperature and rainfall. [Conclusion] This study will provide certain reference for the prediction researches on the time, quantity and occurrence peak of oriental fruit fly.展开更多
Computational tool-assisted primer design for real-time reverse transcription(RT)PCR(qPCR)analysis largely ignores the sequence similarities between sequences of homologous genes in a plant genome.It can lead to false...Computational tool-assisted primer design for real-time reverse transcription(RT)PCR(qPCR)analysis largely ignores the sequence similarities between sequences of homologous genes in a plant genome.It can lead to false confidence in the quality of the designed primers,which sometimes results in skipping the optimization steps for qPCR.However,the optimization of qPCR parameters plays an essential role in the efficiency,specificity,and sensitivity of each gene’s primers.Here,we proposed an optimized approach to sequentially optimizing primer sequences,annealing temperatures,primer concentrations,and cDNA concentration range for each reference(and target)gene.Our approach started with a sequence-specific primer design that should be based on the single-nucleotide polymorphisms(SNPs)present in all the homologous sequences for each of the reference(and target)genes under study.By combining the efficiency calibrated and standard curve methods with the 2−ΔΔCt method,the standard cDNA concentration curve with a logarithmic scale was obtained for each primer pair for each gene.As a result,an R 2≥0.9999 and the efficiency(E)=100±5% should be achieved for the best primer pair of each gene,which serve as the prerequisite for using the 2^(−ΔΔCt) method for data analysis.We applied our newly developed approach to identify the best reference genes in different tissues and at various inflorescence developmental stages of Tripidium ravennae,an ornamental and biomass grass,and validated their utility under varying abiotic stress conditions.We also applied this approach to test the expression stability of six reference genes in soybean under biotic stress treatment with Xanthomonas axonopodis pv.glycines(Xag).Thus,these case studies demonstrated the effectiveness of our optimized protocol for qPCR analysis.展开更多
The idtal time for selecting portal hypertension operation is the accurate judgement of the grade of liver function.yet the present criterion in grading liver functicn is controversial.tco pztitnts vith 20 factoxs rel...The idtal time for selecting portal hypertension operation is the accurate judgement of the grade of liver function.yet the present criterion in grading liver functicn is controversial.tco pztitnts vith 20 factoxs related to poxttl hypeitersor wexe undergone stepwise discriminant analysis by using SAS software on the IBM/PC computer(significance levtl α=0.05).The results show that ascites degree prothrombin tmie(PT),serum total bilirubin,serum albumin content,main portal vein flow are significant fators.In the light of above variates contributing to grading liver function as to estblish a discriminant eqation,it was found that the total agreement rate between replaceable discimination and original Child-Pugh classification is 86%.A test for agieement was performed between discriminant and original classificaton,showing that the two kinds of classification methods have a good agreement rates (Kppa=0.7856),indicating the discriminant classification is of practica values.展开更多
Quantitatively determining the sources of dune sand is one of the problems necessarily and urgently to be solved in aeolian landforms and desertification research. Based on the granulometric data of sand materials fro...Quantitatively determining the sources of dune sand is one of the problems necessarily and urgently to be solved in aeolian landforms and desertification research. Based on the granulometric data of sand materials from the Hulun Buir Sandy Land, the paper employs the stepwise discriminant analysis technique (SDA) for two groups to select the principal factors determining the differences between surface loose sediments. The extent of similarity between two statistical populations can be described quantitatively by three factors such as the number of principal variables, Mahalanobis distance D 2 and confidence level 琢for F-test. Results reveal that: 1) Aeolian dune sand in the region mainly derives from Hailar Formation (Q 3 ), while fluvial sand and palaeosol also supply partially source sand for dunes; and 2) in the vicinity of Cuogang Town and west of the broad valley of the lower reaches of Hailar River, fluvial sand can naturally become principal supplier for dune sand.展开更多
The impact of different global and local variables in urban development processes requires a systematic study to fully comprehend the underlying complexities in them.The interplay between such variables is crucial for...The impact of different global and local variables in urban development processes requires a systematic study to fully comprehend the underlying complexities in them.The interplay between such variables is crucial for modelling urban growth to closely reflects reality.Despite extensive research,ambiguity remains about how variations in these input variables influence urban densification.In this study,we conduct a global sensitivity analysis(SA)using a multinomial logistic regression(MNL)model to assess the model’s explanatory and predictive power.We examine the influence of global variables,including spatial resolution,neighborhood size,and density classes,under different input combinations at a provincial scale to understand their impact on densification.Additionally,we perform a stepwise regression to identify the significant explanatory variables that are important for understanding densification in the Brussels Metropolitan Area(BMA).Our results indicate that a finer spatial resolution of 50 m and 100 m,smaller neighborhood size of 5×5 and 3×3,and specific density classes—namely 3(non-built-up,low and high built-up)and 4(non-built-up,low,medium and high built-up)—optimally explain and predict urban densification.In line with the same,the stepwise regression reveals that models with a coarser resolution of 300 m lack significant variables,reflecting a lower explanatory power for densification.This approach aids in identifying optimal and significant global variables with higher explanatory power for understanding and predicting urban densification.Furthermore,these findings are reproducible in a global urban context,offering valuable insights for planners,modelers and geographers in managing future urban growth and minimizing modelling.展开更多
[Objectivc] This study aimed to investigate the chilling tolerance of seedlings of different cotton genotypes and screen appropriate indicators for assess- ing chilling tolerance, to establish reliable mathematical ev...[Objectivc] This study aimed to investigate the chilling tolerance of seedlings of different cotton genotypes and screen appropriate indicators for assess- ing chilling tolerance, to establish reliable mathematical evaluation model for chilling tolerance of cotton, thus providing theoretical basis for breeding and promoting new chilling-tolerant cotton germplasms and large-scale evaluation of chilling tolerance of cotton varieties. [Method] Fifteen cotton varieties （lines） were used as experimental materials. The photosynthetic gas exchange parameters, chlorophyll fluorescence ki- netic parameters, chlorophyll content, relative soluble sugar content, malonaldehyde content, relative proiine content, relative conductivity and other 12 physiological indi- cators of seedling leaves under low temperature treatment （5 ℃, 12 h） and recovery treatment （25 ℃. 24 h） were determined; based on the chilling tolerance coefficient （CTC） of various individual indicators, the comprehensive evaluation of chilling toler- ance was conducled by using principal component analysis, hierarchical cluster anal- ysis and stepwise regression analysis. [Result] The results showed that the 12 indi- vidual physiological indicators could be classified into 7 independent comprehensive components by principal component analysis; 15 cotton varieties （lines） were clus- tered into three categories by using membership function method and hierarchical cluster analysis; the mathematical model for evaluating chilling tolerance of cotton seedlings was established： D =0.275 -0.244Fo1 ＋0.206Fv/Fm1＋0.326g,%-0.056SS ＋ 0.225MDA＋O.O38REC （FF=0.995）, and the evaluation accuracy of the equation was higher than 94.25%,0. Six identification indicators closely related to chilling tolerance were screened, including Fo,, Fv/Fm1, Seedling leaves of cotton varieties （lines） gs2, SS, MDA, and REC. [Conclusion] with high chilling tolerance are less dam- aged under low temperature stress, and are able to maintain relatively high photo- synthetic electron transport capacity and high stomatal conductance after recovery treatment, which is contributed to gas exchange and recovery of photosynthetic ca- pacity. Determination of the six indicators under the same stress condition can be adopted for rapid identification and prediction of the chilling tolerance of other cotton varieties, which provides basis for the breeding, promotion, identification and screen- ing of chilling tolerant germplasms.展开更多
Five statistical methods including simple correlation, multiple linear regression, stepwise regression, principal components, and path analysis were used to explore the relationship between leaf water use efficiency ...Five statistical methods including simple correlation, multiple linear regression, stepwise regression, principal components, and path analysis were used to explore the relationship between leaf water use efficiency （WUE） and physiological traits （photosynthesis rate, stomatal conductance, transpiration rate, intercellular CO2 concentration, etc.） of 29 wheat cultivars. The results showed that photosynthesis rate, stomatal conductance, and transpiration rate were the most important leaf WUE parameters under drought condition. Based on the results of statistical analyses, principal component analysis could be the most suitable method to ascertain the relationship between leaf WUE and relative physiological traits. It is reasonable to assume that high leaf WUE wheat could be obtained by selecting breeding materials with high photosynthesis rate, low transpiration rate, and stomatal conductance under dry area.展开更多
The COVID-19 pandemic has resulted in over 33 million confirmed cases and over 1 million deaths globally,as of 1 October 2020.During the lockdown and restrictions placed on public activities and gatherings,green space...The COVID-19 pandemic has resulted in over 33 million confirmed cases and over 1 million deaths globally,as of 1 October 2020.During the lockdown and restrictions placed on public activities and gatherings,green spaces have become one of the only sources of resilience amidst the coronavirus pandemic,in part because of their positive effects on psychological,physical and social cohesion and spiritual wellness.This study analyzes the impacts of COVID-19 and government response policies to the pandemic on park visitation at global,regional and national levels and assesses the importance of parks during this global pandemic.The data we collected primarily from Google’s Community Mobility Reports and the Oxford Coronavirus Government Response Tracker.The results for most countries included in the analysis show that park visitation has increased since February 16th,2020 compared to visitor numbers prior to the COVID-19 pandemic.Restrictions on social gathering,movement,and the closure of workplace and indoor recreational places,are correlated with more visits to parks.Stay-at-home restrictions and government stringency index are negatively associated with park visits at a global scale.Demand from residents for parks and outdoor green spaces has increased since the outbreak began,and highlights the important role and benefits provided by parks,especially urban and community parks,under the COVID-19 pandemic.We provide recommendations for park managers and other decision-makers in terms of park management and planning during health crises,as well as for park design and development.In particular,parks could be utilized during pandemics to increase the physical and mental health and social well-being of individuals.展开更多
There are various analytical, empirical and numerical methods to calculate groundwater inflow into tun- nels excavated in rocky media. Analytical methods have been widely applied in prediction of groundwa- ter inflow ...There are various analytical, empirical and numerical methods to calculate groundwater inflow into tun- nels excavated in rocky media. Analytical methods have been widely applied in prediction of groundwa- ter inflow to tunnels due to their simplicity and practical base theory. Investigations show that the real amount of water infiltrating into jointed tunnels is much less than calculated amount using analytical methods and obtained results are very dependent on tunnel＇s geometry and environmental situations. In this study, using multiple regression analysis, a new empirical model for estimation of groundwater seepage into circular tunnels was introduced. Our data was acquired from field surveys and laboratory analysis of core samples. New regression variables were defined after perusing single and two variables relationship between groundwater seepage and other variables. Finally, an appropriate model for estima- tion of leakage was obtained using the stepwise algorithm. Statistics like R, R2, R2e and the histogram of residual values in the model represent a good reputation and fitness for this model to estimate the groundwater seepage into tunnels. The new experimental model was used for the test data and results were satisfactory. Therefore, multiple regression analysis is an effective and efficient way to estimate the groundwater seeoage into tunnels.展开更多
Hydropower has made a significant contribution to the economic development of Vietnam,thus it is important to monitor the safety of hydropower dams for the good of the country and the people.In this paper,dam horizont...Hydropower has made a significant contribution to the economic development of Vietnam,thus it is important to monitor the safety of hydropower dams for the good of the country and the people.In this paper,dam horizontal displacement is analyzed and then forecasted using three methods:the multi-regression model,the seasonal integrated auto-regressive moving average(SARIMA)model and the back-propagation neural network(BPNN)merging models.The monitoring data of the Hoa Binh Dam in Vietnam,including horizontal displacement,time,reservoir water level,and air temperature,are used for the experiments.The results indicate that all of these three methods can approximately describe the trend of dam deformation despite their different forecast accuracies.Hence,their short-term forecasts can provide valuable references for the dam safety.展开更多
To study the relationship between environmental variables and chlorophyll a of spring algal bloom in Xiangxi Bay of Three Gorges Reservoir, stepwise multiple binomial regression and grey relative analysis methods were...To study the relationship between environmental variables and chlorophyll a of spring algal bloom in Xiangxi Bay of Three Gorges Reservoir, stepwise multiple binomial regression and grey relative analysis methods were adopted. In surveys, 13 stations have been investigated and 143 samples were collected weekly from March 4 to May 13 in 2007. The study shows environmental variables (turbidity, total nitrogen, dissolved oxygen, total phosphates and silicate) are key factors during algal bloom. The grey relative values and their permutation indicated that turbidity was the most important factor and had comprehensive effect on chlorophyll a. The more number of interactive variables is found to be an indication of biochemical activity during spring algal bloom in Xiangxi Bay such as DO×TN, Turb×TP and so on. There was good linear relationship between chlorophyll a and the interaction of DO with TN ( , ).The interac-tion of nutrients (TP×TN, TP×SiO4, TN×SiO4) had significant influence to chlorophyll a and probably determined the inter-specific competition at different nutrient concentrations.展开更多
背景:近年来,膝骨关节炎阶梯化手术治疗相关文献数量逐年增加,但缺少相关文献计量学研究。目的:分析2009-2023年全球范围内运用全膝关节置换、单髁置换、胫骨截骨阶梯化手术治疗膝骨关节炎的研究现状,预测3种术式的治疗趋势和发展情况...背景:近年来,膝骨关节炎阶梯化手术治疗相关文献数量逐年增加,但缺少相关文献计量学研究。目的:分析2009-2023年全球范围内运用全膝关节置换、单髁置换、胫骨截骨阶梯化手术治疗膝骨关节炎的研究现状,预测3种术式的治疗趋势和发展情况。方法:从Web of Science核心合集和中国知网(CNKI)中检索2009年1月至2023年12月发表与3种术式相关的文献,使用Microsoft Office Excel 2019、COOC、NoteExpress 4.0.0.9756、文献计量在线分析平台、CiteSpace 6.3.R1、VOSviewer 1.6.20和Biblioshiny进行统计分析和文献可视化分析。结果与结论:①共检索和分析研究类文献英文7102篇、中文2203篇,此领域文献数量呈逐年波动性增加趋势;②分析CNKI的中文文献,《中国组织工程研究》载文量127篇为最多;首都医科大学附属北京积水潭医院矫形骨科发文21篇,为发文最多的机构;聚类分为3部分,一是围术期管理与手术材料技术,二是核心术式与技术创新,三是病因解剖与疗效评估;③分析Web of Science核心合集的英文文献可知,美国发表文献量最多,其次是中国;美国为发表3种术式相关文献总引用量最高的国家,其次是英国,二者与其他国家合作较多;Journal of Arthroplasty刊载文章数量最多,共733篇;纽约特种外科医院是发表文献数量最多的机构,共201篇;④在共现分析中,3种术式相关关键词可以分为3类,分别围绕围术期术式与疗效评估、疾病分类与病理机制、跨关节治疗与综合评估展开;研究全膝关节置换的文献量最大,其次是单髁置换和胫骨截骨,其中单髁置换和胫骨截骨的关键词平均出现时间较晚但处于上升趋势,其中胫骨截骨术也逐渐呈现出追平单髁置换的趋势,全膝关节置换则一直是研究热点;⑤提示随着老龄化趋势加深,膝骨关节炎发病率及该领域发文量将持续增长,“保膝”手术单髁置换和胫骨截骨的研究量将不断增多,全膝关节置换作为骨关节炎终末期治疗的经典手术仍将是研究热点。展开更多
土壤盐碱化是威胁全球农业可持续发展的关键非生物限制因子,严重制约苦荞等耐逆作物的生产潜力。为了筛选苦荞耐盐碱种质资源以及建立耐盐碱评价模型,以160份苦荞种质资源为材料,采用双层滤纸法进行萌发期试验,设置中性盐NaCl、Na_(2)SO...土壤盐碱化是威胁全球农业可持续发展的关键非生物限制因子,严重制约苦荞等耐逆作物的生产潜力。为了筛选苦荞耐盐碱种质资源以及建立耐盐碱评价模型,以160份苦荞种质资源为材料,采用双层滤纸法进行萌发期试验,设置中性盐NaCl、Na_(2)SO_(4)与碱性盐NaHCO_(3)、Na_(2)CO_(3)各5个梯度胁迫,测定发芽势(GP)等5个萌发参数、根长(RL)等4个生长指标,计算各指标的耐盐指数。采用多元统计分析方法对苦荞耐盐性进行综合评价及耐盐指标的筛选。结果表明,9个指标的耐盐系数在不同的盐种类间均存在不同程度的变异,各单项指标间均存在一定的相关性,碱性盐(NaHCO_(3)/Na_(2)CO_(3))对苦荞萌发的抑制阈值(0.10%)显著低于中性盐(0.25%),盐类的抑制强度排序为Na_(2)CO_(3)>NaHCO_(3)>Na_(2)SO_(4)≈NaCl(高浓度时)。通过主成分分析,4种盐均从9个指标的耐盐系数中提取了2个主成分,其累计方差贡献率达80.12%~84.07%,PC1(萌发活力因子,贡献率54.60%~58.13%)包含活力指数(VI)、发芽指数(GI)和发芽率(GR),PC2(生物量因子,贡献率25.21%~27.96%)包含鲜重(FW)、干重(DW)和芽长(SL)。利用隶属函数分析法计算160份苦荞种质资源的综合评价值(D值),并在此基础上采用聚类分析,将种质资源分为高耐(HT)、较耐(RT)、中等(MT)、敏感(SS)、极敏(HS)5个等级,筛选到14份种质在NaCl、Na_(2)SO_(4)、NaHCO_(3)和Na_(2)CO_(3)四种单盐胁迫下均表现出高耐特性。进一步利用逐步回归分析建立最优线性回归方程,NaCl、Na_(2)SO_(4)与NaHCO_(3)筛选出的VI、GI、FW、SL和GR与D值呈显著相关(R^(2)=0.994~0.999,P<0.01),Na_(2)CO_(3)筛选出的GI、FW、SL和RL与D值呈显著相关(R^(2)=0.998,P<0.01),以上可作为耐盐的鉴定指标,活力指数(VI)作为综合生理指标较传统发芽率具有更高的区分度。本研究结果为苦荞耐盐种质资源鉴定及后续开展全基因组关联分析(genome-wide association study,GWAS)挖掘耐盐碱相关的数量性状位点(quantitative trait locus,QTL)及基因奠定了表型组学基础。展开更多
基金The National Natural Science Foundation of China(No.50378016).
文摘Because of the difficulty to obtain the traffic flow information of lanes at non-detector intersections in most metropolises of the world,based on the relationships between the lanes of signal-controlled intersections,cluster analysis and stepwise regression are integrated to predict the traffic volume of lanes at non-detector isolated controlled intersections.First cluster analysis is used to cluster the lanes of non-detector isolated signal-controlled intersections and the lanes of all signal-controlled intersections with detectors.Then, by the results of cluster analysis,the traffic volume samples are selected randomly and stepwise regression is used to predict the traffic volume of lanes at non-detector isolated signal-controlled intersections.The method is tested by the traffic volume data of lanes of the road network of Nanjing city.The problem of predicting the traffic volume of lanes at non-detector isolated signal-controlled intersections was resolved and can be widely used in urban traffic flow guidance and urban traffic control in cities without enough intersections equipped with detectors.
基金Supported by National Key Technology R&D Program in the11th Five Year Plan of China(2006BAD10A14)~~
文摘[Objective] The research aimed to study the significant influence factors of the population variations of oriental fruit fly. [Method] Using stepwise regression analysis, the population variations law of oriental fruit fly in Jianshui County of Yunnan province and the meteorological factors that caused its occurrence were analyzed. And the regression model was built. Finally, the regression model was tested on the basis of the data in Jianshui County of Yunnan Province during 2004-2006.[Result] The main meteorological factors that influenced the occurrence of oriental fruit fly were relative humidity, the lowest monthly temperature and rainfall. [Conclusion] This study will provide certain reference for the prediction researches on the time, quantity and occurrence peak of oriental fruit fly.
基金The authors thank the USDA National Institute of Food and Agriculture Hatch project 02685 and North Carolina State University for the startup funds to the Liu laboratorythe NSFC fund 31871646 to the Zhao laboratory。
文摘Computational tool-assisted primer design for real-time reverse transcription(RT)PCR(qPCR)analysis largely ignores the sequence similarities between sequences of homologous genes in a plant genome.It can lead to false confidence in the quality of the designed primers,which sometimes results in skipping the optimization steps for qPCR.However,the optimization of qPCR parameters plays an essential role in the efficiency,specificity,and sensitivity of each gene’s primers.Here,we proposed an optimized approach to sequentially optimizing primer sequences,annealing temperatures,primer concentrations,and cDNA concentration range for each reference(and target)gene.Our approach started with a sequence-specific primer design that should be based on the single-nucleotide polymorphisms(SNPs)present in all the homologous sequences for each of the reference(and target)genes under study.By combining the efficiency calibrated and standard curve methods with the 2−ΔΔCt method,the standard cDNA concentration curve with a logarithmic scale was obtained for each primer pair for each gene.As a result,an R 2≥0.9999 and the efficiency(E)=100±5% should be achieved for the best primer pair of each gene,which serve as the prerequisite for using the 2^(−ΔΔCt) method for data analysis.We applied our newly developed approach to identify the best reference genes in different tissues and at various inflorescence developmental stages of Tripidium ravennae,an ornamental and biomass grass,and validated their utility under varying abiotic stress conditions.We also applied this approach to test the expression stability of six reference genes in soybean under biotic stress treatment with Xanthomonas axonopodis pv.glycines(Xag).Thus,these case studies demonstrated the effectiveness of our optimized protocol for qPCR analysis.
文摘The idtal time for selecting portal hypertension operation is the accurate judgement of the grade of liver function.yet the present criterion in grading liver functicn is controversial.tco pztitnts vith 20 factoxs related to poxttl hypeitersor wexe undergone stepwise discriminant analysis by using SAS software on the IBM/PC computer(significance levtl α=0.05).The results show that ascites degree prothrombin tmie(PT),serum total bilirubin,serum albumin content,main portal vein flow are significant fators.In the light of above variates contributing to grading liver function as to estblish a discriminant eqation,it was found that the total agreement rate between replaceable discimination and original Child-Pugh classification is 86%.A test for agieement was performed between discriminant and original classificaton,showing that the two kinds of classification methods have a good agreement rates (Kppa=0.7856),indicating the discriminant classification is of practica values.
文摘Quantitatively determining the sources of dune sand is one of the problems necessarily and urgently to be solved in aeolian landforms and desertification research. Based on the granulometric data of sand materials from the Hulun Buir Sandy Land, the paper employs the stepwise discriminant analysis technique (SDA) for two groups to select the principal factors determining the differences between surface loose sediments. The extent of similarity between two statistical populations can be described quantitatively by three factors such as the number of principal variables, Mahalanobis distance D 2 and confidence level 琢for F-test. Results reveal that: 1) Aeolian dune sand in the region mainly derives from Hailar Formation (Q 3 ), while fluvial sand and palaeosol also supply partially source sand for dunes; and 2) in the vicinity of Cuogang Town and west of the broad valley of the lower reaches of Hailar River, fluvial sand can naturally become principal supplier for dune sand.
基金funded by the INTER program and cofunded by the Fond National de la Recherche,Luxembourg(FNR)and the Fund for Scientific Research-FNRS,Belgium(F.R.S-FNRS),T.0233.20-‘Sustainable Residential Densification’project(SusDens,2020–2024).
文摘The impact of different global and local variables in urban development processes requires a systematic study to fully comprehend the underlying complexities in them.The interplay between such variables is crucial for modelling urban growth to closely reflects reality.Despite extensive research,ambiguity remains about how variations in these input variables influence urban densification.In this study,we conduct a global sensitivity analysis(SA)using a multinomial logistic regression(MNL)model to assess the model’s explanatory and predictive power.We examine the influence of global variables,including spatial resolution,neighborhood size,and density classes,under different input combinations at a provincial scale to understand their impact on densification.Additionally,we perform a stepwise regression to identify the significant explanatory variables that are important for understanding densification in the Brussels Metropolitan Area(BMA).Our results indicate that a finer spatial resolution of 50 m and 100 m,smaller neighborhood size of 5×5 and 3×3,and specific density classes—namely 3(non-built-up,low and high built-up)and 4(non-built-up,low,medium and high built-up)—optimally explain and predict urban densification.In line with the same,the stepwise regression reveals that models with a coarser resolution of 300 m lack significant variables,reflecting a lower explanatory power for densification.This approach aids in identifying optimal and significant global variables with higher explanatory power for understanding and predicting urban densification.Furthermore,these findings are reproducible in a global urban context,offering valuable insights for planners,modelers and geographers in managing future urban growth and minimizing modelling.
基金Supported by"11thFive-Year Plan"National Science and Technology Support Program(2009BADA4B01-3)~~
文摘[Objectivc] This study aimed to investigate the chilling tolerance of seedlings of different cotton genotypes and screen appropriate indicators for assess- ing chilling tolerance, to establish reliable mathematical evaluation model for chilling tolerance of cotton, thus providing theoretical basis for breeding and promoting new chilling-tolerant cotton germplasms and large-scale evaluation of chilling tolerance of cotton varieties. [Method] Fifteen cotton varieties （lines） were used as experimental materials. The photosynthetic gas exchange parameters, chlorophyll fluorescence ki- netic parameters, chlorophyll content, relative soluble sugar content, malonaldehyde content, relative proiine content, relative conductivity and other 12 physiological indi- cators of seedling leaves under low temperature treatment （5 ℃, 12 h） and recovery treatment （25 ℃. 24 h） were determined; based on the chilling tolerance coefficient （CTC） of various individual indicators, the comprehensive evaluation of chilling toler- ance was conducled by using principal component analysis, hierarchical cluster anal- ysis and stepwise regression analysis. [Result] The results showed that the 12 indi- vidual physiological indicators could be classified into 7 independent comprehensive components by principal component analysis; 15 cotton varieties （lines） were clus- tered into three categories by using membership function method and hierarchical cluster analysis; the mathematical model for evaluating chilling tolerance of cotton seedlings was established： D =0.275 -0.244Fo1 ＋0.206Fv/Fm1＋0.326g,%-0.056SS ＋ 0.225MDA＋O.O38REC （FF=0.995）, and the evaluation accuracy of the equation was higher than 94.25%,0. Six identification indicators closely related to chilling tolerance were screened, including Fo,, Fv/Fm1, Seedling leaves of cotton varieties （lines） gs2, SS, MDA, and REC. [Conclusion] with high chilling tolerance are less dam- aged under low temperature stress, and are able to maintain relatively high photo- synthetic electron transport capacity and high stomatal conductance after recovery treatment, which is contributed to gas exchange and recovery of photosynthetic ca- pacity. Determination of the six indicators under the same stress condition can be adopted for rapid identification and prediction of the chilling tolerance of other cotton varieties, which provides basis for the breeding, promotion, identification and screen- ing of chilling tolerant germplasms.
基金supported by the Key Technologies R&D Program of China during the 11th Five-Year Plan period (2008BAD98B03)
文摘Five statistical methods including simple correlation, multiple linear regression, stepwise regression, principal components, and path analysis were used to explore the relationship between leaf water use efficiency （WUE） and physiological traits （photosynthesis rate, stomatal conductance, transpiration rate, intercellular CO2 concentration, etc.） of 29 wheat cultivars. The results showed that photosynthesis rate, stomatal conductance, and transpiration rate were the most important leaf WUE parameters under drought condition. Based on the results of statistical analyses, principal component analysis could be the most suitable method to ascertain the relationship between leaf WUE and relative physiological traits. It is reasonable to assume that high leaf WUE wheat could be obtained by selecting breeding materials with high photosynthesis rate, low transpiration rate, and stomatal conductance under dry area.
基金supported by the APFNet National Park Research Project(2017SP2-UBC).
文摘The COVID-19 pandemic has resulted in over 33 million confirmed cases and over 1 million deaths globally,as of 1 October 2020.During the lockdown and restrictions placed on public activities and gatherings,green spaces have become one of the only sources of resilience amidst the coronavirus pandemic,in part because of their positive effects on psychological,physical and social cohesion and spiritual wellness.This study analyzes the impacts of COVID-19 and government response policies to the pandemic on park visitation at global,regional and national levels and assesses the importance of parks during this global pandemic.The data we collected primarily from Google’s Community Mobility Reports and the Oxford Coronavirus Government Response Tracker.The results for most countries included in the analysis show that park visitation has increased since February 16th,2020 compared to visitor numbers prior to the COVID-19 pandemic.Restrictions on social gathering,movement,and the closure of workplace and indoor recreational places,are correlated with more visits to parks.Stay-at-home restrictions and government stringency index are negatively associated with park visits at a global scale.Demand from residents for parks and outdoor green spaces has increased since the outbreak began,and highlights the important role and benefits provided by parks,especially urban and community parks,under the COVID-19 pandemic.We provide recommendations for park managers and other decision-makers in terms of park management and planning during health crises,as well as for park design and development.In particular,parks could be utilized during pandemics to increase the physical and mental health and social well-being of individuals.
文摘There are various analytical, empirical and numerical methods to calculate groundwater inflow into tun- nels excavated in rocky media. Analytical methods have been widely applied in prediction of groundwa- ter inflow to tunnels due to their simplicity and practical base theory. Investigations show that the real amount of water infiltrating into jointed tunnels is much less than calculated amount using analytical methods and obtained results are very dependent on tunnel＇s geometry and environmental situations. In this study, using multiple regression analysis, a new empirical model for estimation of groundwater seepage into circular tunnels was introduced. Our data was acquired from field surveys and laboratory analysis of core samples. New regression variables were defined after perusing single and two variables relationship between groundwater seepage and other variables. Finally, an appropriate model for estima- tion of leakage was obtained using the stepwise algorithm. Statistics like R, R2, R2e and the histogram of residual values in the model represent a good reputation and fitness for this model to estimate the groundwater seepage into tunnels. The new experimental model was used for the test data and results were satisfactory. Therefore, multiple regression analysis is an effective and efficient way to estimate the groundwater seeoage into tunnels.
基金This research was funded by the China Scholarship Council(CSC)and partially supported by the Project 911(Vietnam).The data analysis was carried out as a part of the second author’s PhD studies at the School of Geodesy and Geomatics,Wuhan University,People’s Republic of China[grant number 2011GXZN02].
文摘Hydropower has made a significant contribution to the economic development of Vietnam,thus it is important to monitor the safety of hydropower dams for the good of the country and the people.In this paper,dam horizontal displacement is analyzed and then forecasted using three methods:the multi-regression model,the seasonal integrated auto-regressive moving average(SARIMA)model and the back-propagation neural network(BPNN)merging models.The monitoring data of the Hoa Binh Dam in Vietnam,including horizontal displacement,time,reservoir water level,and air temperature,are used for the experiments.The results indicate that all of these three methods can approximately describe the trend of dam deformation despite their different forecast accuracies.Hence,their short-term forecasts can provide valuable references for the dam safety.
文摘To study the relationship between environmental variables and chlorophyll a of spring algal bloom in Xiangxi Bay of Three Gorges Reservoir, stepwise multiple binomial regression and grey relative analysis methods were adopted. In surveys, 13 stations have been investigated and 143 samples were collected weekly from March 4 to May 13 in 2007. The study shows environmental variables (turbidity, total nitrogen, dissolved oxygen, total phosphates and silicate) are key factors during algal bloom. The grey relative values and their permutation indicated that turbidity was the most important factor and had comprehensive effect on chlorophyll a. The more number of interactive variables is found to be an indication of biochemical activity during spring algal bloom in Xiangxi Bay such as DO×TN, Turb×TP and so on. There was good linear relationship between chlorophyll a and the interaction of DO with TN ( , ).The interac-tion of nutrients (TP×TN, TP×SiO4, TN×SiO4) had significant influence to chlorophyll a and probably determined the inter-specific competition at different nutrient concentrations.
文摘背景:近年来,膝骨关节炎阶梯化手术治疗相关文献数量逐年增加,但缺少相关文献计量学研究。目的:分析2009-2023年全球范围内运用全膝关节置换、单髁置换、胫骨截骨阶梯化手术治疗膝骨关节炎的研究现状,预测3种术式的治疗趋势和发展情况。方法:从Web of Science核心合集和中国知网(CNKI)中检索2009年1月至2023年12月发表与3种术式相关的文献,使用Microsoft Office Excel 2019、COOC、NoteExpress 4.0.0.9756、文献计量在线分析平台、CiteSpace 6.3.R1、VOSviewer 1.6.20和Biblioshiny进行统计分析和文献可视化分析。结果与结论:①共检索和分析研究类文献英文7102篇、中文2203篇,此领域文献数量呈逐年波动性增加趋势;②分析CNKI的中文文献,《中国组织工程研究》载文量127篇为最多;首都医科大学附属北京积水潭医院矫形骨科发文21篇,为发文最多的机构;聚类分为3部分,一是围术期管理与手术材料技术,二是核心术式与技术创新,三是病因解剖与疗效评估;③分析Web of Science核心合集的英文文献可知,美国发表文献量最多,其次是中国;美国为发表3种术式相关文献总引用量最高的国家,其次是英国,二者与其他国家合作较多;Journal of Arthroplasty刊载文章数量最多,共733篇;纽约特种外科医院是发表文献数量最多的机构,共201篇;④在共现分析中,3种术式相关关键词可以分为3类,分别围绕围术期术式与疗效评估、疾病分类与病理机制、跨关节治疗与综合评估展开;研究全膝关节置换的文献量最大,其次是单髁置换和胫骨截骨,其中单髁置换和胫骨截骨的关键词平均出现时间较晚但处于上升趋势,其中胫骨截骨术也逐渐呈现出追平单髁置换的趋势,全膝关节置换则一直是研究热点;⑤提示随着老龄化趋势加深,膝骨关节炎发病率及该领域发文量将持续增长,“保膝”手术单髁置换和胫骨截骨的研究量将不断增多,全膝关节置换作为骨关节炎终末期治疗的经典手术仍将是研究热点。
文摘土壤盐碱化是威胁全球农业可持续发展的关键非生物限制因子,严重制约苦荞等耐逆作物的生产潜力。为了筛选苦荞耐盐碱种质资源以及建立耐盐碱评价模型,以160份苦荞种质资源为材料,采用双层滤纸法进行萌发期试验,设置中性盐NaCl、Na_(2)SO_(4)与碱性盐NaHCO_(3)、Na_(2)CO_(3)各5个梯度胁迫,测定发芽势(GP)等5个萌发参数、根长(RL)等4个生长指标,计算各指标的耐盐指数。采用多元统计分析方法对苦荞耐盐性进行综合评价及耐盐指标的筛选。结果表明,9个指标的耐盐系数在不同的盐种类间均存在不同程度的变异,各单项指标间均存在一定的相关性,碱性盐(NaHCO_(3)/Na_(2)CO_(3))对苦荞萌发的抑制阈值(0.10%)显著低于中性盐(0.25%),盐类的抑制强度排序为Na_(2)CO_(3)>NaHCO_(3)>Na_(2)SO_(4)≈NaCl(高浓度时)。通过主成分分析,4种盐均从9个指标的耐盐系数中提取了2个主成分,其累计方差贡献率达80.12%~84.07%,PC1(萌发活力因子,贡献率54.60%~58.13%)包含活力指数(VI)、发芽指数(GI)和发芽率(GR),PC2(生物量因子,贡献率25.21%~27.96%)包含鲜重(FW)、干重(DW)和芽长(SL)。利用隶属函数分析法计算160份苦荞种质资源的综合评价值(D值),并在此基础上采用聚类分析,将种质资源分为高耐(HT)、较耐(RT)、中等(MT)、敏感(SS)、极敏(HS)5个等级,筛选到14份种质在NaCl、Na_(2)SO_(4)、NaHCO_(3)和Na_(2)CO_(3)四种单盐胁迫下均表现出高耐特性。进一步利用逐步回归分析建立最优线性回归方程,NaCl、Na_(2)SO_(4)与NaHCO_(3)筛选出的VI、GI、FW、SL和GR与D值呈显著相关(R^(2)=0.994~0.999,P<0.01),Na_(2)CO_(3)筛选出的GI、FW、SL和RL与D值呈显著相关(R^(2)=0.998,P<0.01),以上可作为耐盐的鉴定指标,活力指数(VI)作为综合生理指标较传统发芽率具有更高的区分度。本研究结果为苦荞耐盐种质资源鉴定及后续开展全基因组关联分析(genome-wide association study,GWAS)挖掘耐盐碱相关的数量性状位点(quantitative trait locus,QTL)及基因奠定了表型组学基础。
