The design of columns relies heavily on the basis of Leonhard Euler’s Theory of Elastic Buckling.However,to increase the accuracy in determining the maximum critical load a column can withstand before buckling,a cons...The design of columns relies heavily on the basis of Leonhard Euler’s Theory of Elastic Buckling.However,to increase the accuracy in determining the maximum critical load a column can withstand before buckling,a constant was introduced.This dimensionless coefficient is K,also known as the effective-length factor.This constant is often found in building design codes and varies in value depending on the type of column support that is applied.This paper presents experimental and analytical studies on the determination of the effective-length factor in the buckling stability of columns with partially-fixed support conditions.To this end,the accurate K value of the columns tested by the Instron Testing Machine(ITM)at California State University,Northridge’s(CSUN’s)Mechanics Laboratory is determined.The ITM is used in studying the buckling of columns where the supports are neither pinned nor fixed,and the material cross-section rather rests upon the machine while loading is applied axially.Several column specimens were tested and the experimental data were analyzed in order to estimation of the accurate effective-length factor.The calculations from the tested results as well as the conducted probabilistic analysis shed light on how a fragility curve may aid in predicting the effective-length value of future tests.展开更多
Ultrasonic biometry was done in 232 normal eyes and 138 eyes with primary angle closure glaucoma (ACG), using Ultrascan Digital B System IV (10 MHz). The ratio between the lens thickness and the axial length (lens thi...Ultrasonic biometry was done in 232 normal eyes and 138 eyes with primary angle closure glaucoma (ACG), using Ultrascan Digital B System IV (10 MHz). The ratio between the lens thickness and the axial length (lens thickness to axial length factor, LAF) was evaluated as a biometric index for assessing the eye with primary ACG in Chinese. LAF of 2.00 was found to be ideal point of demarcation between ACG and normal eyes (i.e., lens thickness equals to 1/5 of axial length). It appears that LAF is helpful i...展开更多
In previous work, the electron radius was identified as the “actual electron radius.” However, this is more accurately described as the electron radius at rest. This study reexamines the electron with an emphasis on...In previous work, the electron radius was identified as the “actual electron radius.” However, this is more accurately described as the electron radius at rest. This study reexamines the electron with an emphasis on the electron radius under motion, incorporating the effects of length contraction. The findings suggest that the radius is subject to Lorentz contraction, which has interesting implications for relativistic effects at the subatomic level.展开更多
The slope length factor is one of the parameters of the Universal Soil Loss Equation(USLE)and the Revised Universal Soil Loss Equation(RUSLE)and is sometimes calculated based on a digital elevation model(DEM).The meth...The slope length factor is one of the parameters of the Universal Soil Loss Equation(USLE)and the Revised Universal Soil Loss Equation(RUSLE)and is sometimes calculated based on a digital elevation model(DEM).The methods for calculating the slope length factor are important because the values obtained may depend on the methods used for calculation.The purpose of this study was to compare the difference in spatial distribution of the slope length factor between the different methods at a watershed scale.One method used the uniform slope length factor equation(USLFE)where the effects of slope irregularities(such as slope gradient,etc.)on soil erosion by water were not considered.The other method used segmented slope length factor equation(SSLFE)which considered the effects of slope irregularities on soil erosion by water.The Arc Macro Language(AML)Version 4 program for the revised universal soil loss equation(RUSLE).which uses the USLFE,was chosen to calculate the slope length factor.In a parallel analysis,the AML code of RUSLE Version 4 was modified according to the SSLFE to calculate the slope length factor.Two watersheds with different slope and gully densities were chosen.The results show that the slope length factor and soil loss using the USLFE method were lower than those using the SSLFE method,especially on downslopes watershed with more frequent steep slopes and higher gully densities.In addition,the slope length factor and soil loss calculated by the USLFE showed less spatial variation.展开更多
Background: Geographic variation in body size is assumed to reflect adaptation to local environmental conditions. Although Bergmann's rule is usually sufficient to explain such variation in homeotherms, some excep...Background: Geographic variation in body size is assumed to reflect adaptation to local environmental conditions. Although Bergmann's rule is usually sufficient to explain such variation in homeotherms, some exceptions have been documented. The relationship between altitude, latitude and body size, has been well documented for some vertebrate taxa during the past decades. However, relatively little information is available on the effects of climate variables on body size in birds.Methods: We collected the data of 267 adult Eurasian Tree Sparrow(Passer montanus) specimens sampled at 48 localities in China's mainland, and further investigated the relationships between two response variables, body mass and wing length, as well as a suit of explanatory variables, i.e. altitude, latitude, mean annual temperature(MAT), annual precipitation(PRC), annual sunshine hours(SUN), average annual wind speed(WS), air pressure(AP) and relative humidity(RH).Results: Our study showed that(1) although the sexes did not differ significantly in body mass, males had longer wings than females;(2) body mass and wing length were positively correlated with altitude but not with latitude;(3) body mass and wing length were negatively correlated with AP and RH, but not significantly correlated with WS. Body mass was positively correlated with SUN and inversely correlated with MAT. Wing length was not correlated with MAT in either sex, but was positively correlated with SUN and negatively correlated with PRC in male sparrows;(4) variation in body mass could be best explained by AP and SUN, whereas variation in wing length could be explained by RH and AP in both sexes. In addition, variation in male sparrows can be explained by SUN, WS and PRC but not in females.Conclusions: Two different proxies of body size, body mass and wing length, correlated with same geographic factors and different climate factors. These differences may reflect selection for heat conservation in the case of body mass, and for efficient flight in the case of wing length.展开更多
目的探讨影响单侧髋膝关节置换术后住院时间(length of stay,LOS)的围术期因素。方法通过筛选纳入我院行单侧髋或膝关节置换术的患者1490例;记录术前一般情况、合并症、药物使用、手术方式、手术医生、麻醉方式、麻醉用药、手术时间、...目的探讨影响单侧髋膝关节置换术后住院时间(length of stay,LOS)的围术期因素。方法通过筛选纳入我院行单侧髋或膝关节置换术的患者1490例;记录术前一般情况、合并症、药物使用、手术方式、手术医生、麻醉方式、麻醉用药、手术时间、液体出入量和种类等相关参数;采用单因素、多因素线性回归模型,分析患者关节置换术后影响LOS的因素。结果术后LOS为(9.63±5.13)d;THA、TKA和股骨头置换术后LOS分别为(8.80±4.70)d、(10.25±4.41)d和(11.94±7.09)d;手术时长(97.00±43.00)min;术后情况有急性肾功能损伤(AKI)80例(5.4%)、转入ICU病房99例(6.6%)、死亡5例(0.3%);其中年龄(P<0.001)、术前合并肺部感染(P=0.004)、手术医生的手术量和工作年限(P<0.001)、术中异体红细胞输注(P=0.028)、手术时长(P<0.001)、术后进入ICU(P<0.001)及术后发生AKI(P=0.047)与LOS的变化有显著相关性;术中异体红细胞输注患者LOS增加2 d;术后入住ICU比未入住者LOS延长4 d;术后发生AKI的患者LOS增加3 d。结论年龄>70岁、术前合并肺部感染、手术时间>120 min、工作年限短和年手术量少的手术医生、术中输注红细胞、术后转入ICU以及发生AKI是髋膝关节置换术后LOS增加的独立风险因素。展开更多
Human activities to improve the quality of life have accelerated the natural rate of soil erosion.In turn,these natural disasters have taken a great impact on humans.Human activities,particularly the conversion of veg...Human activities to improve the quality of life have accelerated the natural rate of soil erosion.In turn,these natural disasters have taken a great impact on humans.Human activities,particularly the conversion of vegetated land into agricultural land and built-up area,stand out as primary contributors to soil erosion.The present study investigated the risk of soil erosion in the Irga watershed located on the eastern fringe of the Chota Nagpur Plateau in Jharkhand,India,which is dominated by sandy loam and sandy clay loam soil with low soil organic carbon(SOC)content.The study used the Revised Universal Soil Loss Equation(RUSLE)and Geographical Information System(GIS)technique to determine the rate of soil erosion.The five parameters(rainfall-runoff erosivity(R)factor,soil erodibility(K)factor,slope length and steepness(LS)factor,cover-management(C)factor,and support practice(P)factor)of the RUSLE were applied to present a more accurate distribution characteristic of soil erosion in the Irga watershed.The result shows that the R factor is positively correlated with rainfall and follows the same distribution pattern as the rainfall.The K factor values in the northern part of the study area are relatively low,while they are relatively high in the southern part.The mean value of the LS factor is 2.74,which is low due to the flat terrain of the Irga watershed.There is a negative linear correlation between Normalized Difference Vegetation Index(NDVI)and the C factor,and the high values of the C factor are observed in places with low NDVI.The mean value of the P factor is 0.210,with a range from 0.000 to 1.000.After calculating all parameters,we obtained the average soil erosion rate of 1.43 t/(hm^(2)•a),with the highest rate reaching as high as 32.71 t/(hm^(2)•a).Therefore,the study area faces a low risk of soil erosion.However,preventative measures are essential to avoid future damage to productive and constructive activities caused by soil erosion.This study also identifies the spatial distribution of soil erosion rate,which will help policy-makers to implement targeted soil erosion control measures.展开更多
基金The authors would like to express their great appreciation for funding made possible in support of this research endeavor through the CSU-LSAMP(California State University Louis Stokes Alliance for Minority Participation)program via the NSF(National Science Foundation)grant#HRD-1302873the Chancellor’s Office of the California State University。
文摘The design of columns relies heavily on the basis of Leonhard Euler’s Theory of Elastic Buckling.However,to increase the accuracy in determining the maximum critical load a column can withstand before buckling,a constant was introduced.This dimensionless coefficient is K,also known as the effective-length factor.This constant is often found in building design codes and varies in value depending on the type of column support that is applied.This paper presents experimental and analytical studies on the determination of the effective-length factor in the buckling stability of columns with partially-fixed support conditions.To this end,the accurate K value of the columns tested by the Instron Testing Machine(ITM)at California State University,Northridge’s(CSUN’s)Mechanics Laboratory is determined.The ITM is used in studying the buckling of columns where the supports are neither pinned nor fixed,and the material cross-section rather rests upon the machine while loading is applied axially.Several column specimens were tested and the experimental data were analyzed in order to estimation of the accurate effective-length factor.The calculations from the tested results as well as the conducted probabilistic analysis shed light on how a fragility curve may aid in predicting the effective-length value of future tests.
文摘Ultrasonic biometry was done in 232 normal eyes and 138 eyes with primary angle closure glaucoma (ACG), using Ultrascan Digital B System IV (10 MHz). The ratio between the lens thickness and the axial length (lens thickness to axial length factor, LAF) was evaluated as a biometric index for assessing the eye with primary ACG in Chinese. LAF of 2.00 was found to be ideal point of demarcation between ACG and normal eyes (i.e., lens thickness equals to 1/5 of axial length). It appears that LAF is helpful i...
文摘In previous work, the electron radius was identified as the “actual electron radius.” However, this is more accurately described as the electron radius at rest. This study reexamines the electron with an emphasis on the electron radius under motion, incorporating the effects of length contraction. The findings suggest that the radius is subject to Lorentz contraction, which has interesting implications for relativistic effects at the subatomic level.
基金Research for this paper was funded by Program for Changjiang Scholars and Innovative Research Team in University and the Fundamental Research Funds for the Central Universities.
文摘The slope length factor is one of the parameters of the Universal Soil Loss Equation(USLE)and the Revised Universal Soil Loss Equation(RUSLE)and is sometimes calculated based on a digital elevation model(DEM).The methods for calculating the slope length factor are important because the values obtained may depend on the methods used for calculation.The purpose of this study was to compare the difference in spatial distribution of the slope length factor between the different methods at a watershed scale.One method used the uniform slope length factor equation(USLFE)where the effects of slope irregularities(such as slope gradient,etc.)on soil erosion by water were not considered.The other method used segmented slope length factor equation(SSLFE)which considered the effects of slope irregularities on soil erosion by water.The Arc Macro Language(AML)Version 4 program for the revised universal soil loss equation(RUSLE).which uses the USLFE,was chosen to calculate the slope length factor.In a parallel analysis,the AML code of RUSLE Version 4 was modified according to the SSLFE to calculate the slope length factor.Two watersheds with different slope and gully densities were chosen.The results show that the slope length factor and soil loss using the USLFE method were lower than those using the SSLFE method,especially on downslopes watershed with more frequent steep slopes and higher gully densities.In addition,the slope length factor and soil loss calculated by the USLFE showed less spatial variation.
基金supported by grants from the National Natural Science Foundation of China (NSFC, 31330073, 31672292)the Natural Science Foundation of the Department of Education, Hebei Province (YQ2014024)
文摘Background: Geographic variation in body size is assumed to reflect adaptation to local environmental conditions. Although Bergmann's rule is usually sufficient to explain such variation in homeotherms, some exceptions have been documented. The relationship between altitude, latitude and body size, has been well documented for some vertebrate taxa during the past decades. However, relatively little information is available on the effects of climate variables on body size in birds.Methods: We collected the data of 267 adult Eurasian Tree Sparrow(Passer montanus) specimens sampled at 48 localities in China's mainland, and further investigated the relationships between two response variables, body mass and wing length, as well as a suit of explanatory variables, i.e. altitude, latitude, mean annual temperature(MAT), annual precipitation(PRC), annual sunshine hours(SUN), average annual wind speed(WS), air pressure(AP) and relative humidity(RH).Results: Our study showed that(1) although the sexes did not differ significantly in body mass, males had longer wings than females;(2) body mass and wing length were positively correlated with altitude but not with latitude;(3) body mass and wing length were negatively correlated with AP and RH, but not significantly correlated with WS. Body mass was positively correlated with SUN and inversely correlated with MAT. Wing length was not correlated with MAT in either sex, but was positively correlated with SUN and negatively correlated with PRC in male sparrows;(4) variation in body mass could be best explained by AP and SUN, whereas variation in wing length could be explained by RH and AP in both sexes. In addition, variation in male sparrows can be explained by SUN, WS and PRC but not in females.Conclusions: Two different proxies of body size, body mass and wing length, correlated with same geographic factors and different climate factors. These differences may reflect selection for heat conservation in the case of body mass, and for efficient flight in the case of wing length.
基金the financial support received from the University Grants Commission (UGC) in the form of a Junior Research Fellowship (JRF)。
文摘Human activities to improve the quality of life have accelerated the natural rate of soil erosion.In turn,these natural disasters have taken a great impact on humans.Human activities,particularly the conversion of vegetated land into agricultural land and built-up area,stand out as primary contributors to soil erosion.The present study investigated the risk of soil erosion in the Irga watershed located on the eastern fringe of the Chota Nagpur Plateau in Jharkhand,India,which is dominated by sandy loam and sandy clay loam soil with low soil organic carbon(SOC)content.The study used the Revised Universal Soil Loss Equation(RUSLE)and Geographical Information System(GIS)technique to determine the rate of soil erosion.The five parameters(rainfall-runoff erosivity(R)factor,soil erodibility(K)factor,slope length and steepness(LS)factor,cover-management(C)factor,and support practice(P)factor)of the RUSLE were applied to present a more accurate distribution characteristic of soil erosion in the Irga watershed.The result shows that the R factor is positively correlated with rainfall and follows the same distribution pattern as the rainfall.The K factor values in the northern part of the study area are relatively low,while they are relatively high in the southern part.The mean value of the LS factor is 2.74,which is low due to the flat terrain of the Irga watershed.There is a negative linear correlation between Normalized Difference Vegetation Index(NDVI)and the C factor,and the high values of the C factor are observed in places with low NDVI.The mean value of the P factor is 0.210,with a range from 0.000 to 1.000.After calculating all parameters,we obtained the average soil erosion rate of 1.43 t/(hm^(2)•a),with the highest rate reaching as high as 32.71 t/(hm^(2)•a).Therefore,the study area faces a low risk of soil erosion.However,preventative measures are essential to avoid future damage to productive and constructive activities caused by soil erosion.This study also identifies the spatial distribution of soil erosion rate,which will help policy-makers to implement targeted soil erosion control measures.
