基于PMF-PCA/APCS与PERI的菏泽油用牡丹种植区表层土壤重金属潜在来源识别及生态风险评估

研究特色农产品产区土壤重金属来源及其潜在风险,对科学管理、安全利用土壤和作物资源具有重要意义.以菏泽油用牡丹种植区为研究对象,采集并测定了254件表层土壤样品As、Cd、Cr、Cu、Hg、Ni、Pb和Zn等8种重金属的含量.采用多元统计法分析了重金属的含量特征及相关性,利用地累积指数（I_geo）、正定矩阵因子分解法（PMF）和主成分分析/绝对主成分分数法（PCA/APCS）相结合的手段解析了表层土壤中重金属的来源,借助潜在生态风险指数（PERI）对该8种重金属的生态风险进行了评估.结果表明,土壤中除Cd元素的平均值高于菏泽市背景值1.44倍之外,其余7种重金属的平均含量均与菏泽市土壤元素背景值基本一致;经相关分析和聚类分析,土壤中Pb、Hg和Cd元素受后期人为活动的干扰影响较大;研究区8种重金属的来源为自然源、农业化肥源、工业燃煤源和生活交通源,贡献率分别为81.31%、15.45%、2.74%和0.50%;研究区84.25%的点位处于轻微生态风险,而中度风险和强风险点位占比分别为14.96%和0.79%,其中Cd和Hg是研究区生态风险主导元素.     

蒙城地震台地磁绝对观测数据处理分析软件

蒙城地震台地磁绝对观测数据主要通过手工方式计算处理,由于内容多而繁琐,很容易出现人为错误,而且工作效率不高。本文介绍了“蒙城地震台地磁绝对观测数据处理分析软件”,该软件将绝对观测日常数据处理工作有效整合,形成了流程,提高了数据处理效率。并能够对数据进行误差统计、趋势分析等,以了解观测资料的实际状况。     

The estimated reduction in the odds of loss-of-control type crashes for sport utility vehicles equipped with electronic stability control

INTRODUCTION: Using data from the NASS General Estimates System (GES), the method of induced exposure was used to assess the effects of electronic stability control (ESC) on loss-of-control type crashes for sport utility vehicles. METHOD: Sport utility vehicles were classified into crash types generally associated with loss of control and crash types most likely not associated with loss of control. Vehicles were then compared as to whether ESC technology was present or absent in the vehicles. A generalized additive model was fit to assess the effects of ESC, driver age, and driver gender on the odds of loss of control. In addition, the effects of ESC on roads that were not dry were compared to effects on roads that were dry. RESULTS: Overall, the estimated percentage reduction in the odds of a loss-of-control crash for sport utility vehicles equipped with ESC was 70.3%. Both genders and all age groups showed reduced odds of loss-of-control crashes, but there was no significant difference between males and females. With respect to driver age, the maximum percentage reduction of 73.6% occurred at age 27. The positive effects of ESC on roads that were not dry were significantly greater than on roads that were dry.     

Demography and disappearing merchandise: How older workforces influence retail shrinkage

Prior research on retail shrinkage has taken a largely individual‐level approach to theorizing about why it occurs, showing that older employees are less prone to theft and more vigilant in preventing customer shoplifting than younger personnel. However, given the influence of organizational contexts on organizational behavior, theorizing about shrinkage may be enhanced by the consideration of business‐unit level contextual variables. The present study addressed this concern by examining the relationship between store‐level age composition, whistle‐blowing (WB) climate, and shrinkage in 726 retail stores. Results indicated that the negative mean age–shrinkage relationship was stronger when there was less age diversity or a climate more supportive of WB. Moreover, the negative WB climate–shrinkage linkage was stronger when the mean age was higher. Copyright © 2011 John Wiley & Sons, Ltd.     

Comparison of Canadian firefighters and healthy controls based on submaximal fitness testing and strength considering age and gender

Introduction. Few studies have addressed whether firefighters are fitter than the general population and possess sufficient levels of aerobic capacity and muscle strength to perform on-duty tasks in a safe and efficient manner, considering age and gender. We aimed to evaluate the fitness levels of Hamilton firefighters, and to determine the effects of age and gender. Methods. In total, 89 participants were recruited. The modified Canadian aerobic fitness test was used to determine participants’ estimated maximal oxygen consumption (V_O2max) levels. For upper and lower body strength levels, a calibrated J-Tech hand-held dynamometer and a National Institute for Occupational Safety and Health (NIOSH) lifting device was used respectively. Results. Firefighters’ mean (SD) V_O2max level was 40.30?±?6.25?ml·kg^?1·min^?1. Age proved to have a statistically significant impact on V_O2max (p?<?0.001). Gender displayed statistically significant effects on strength levels. Firefighters’ age was the only statistically significant independent variable, and accounted for 61.00% of the variance in firefighters’ aerobic capacity levels. Conclusions. Firefighters possessed somewhat similar aerobic capacities but much higher levels of body strength when compared with the general population. With age, firefighters’ aerobic capacities decreased; however, their upper and lower body strength levels remained the same.     

浙江天台山茶树光合日变化及光响应

自然条件下使用LCA－4型便携式光合测定系统研究了栽培天天台山主峰华顶山的茶树连体叶片的光合日变化及光响应。结果表明：在初夏晴天,上年越冬叶片（下称二年生叶）的光合速率,表观量子效率,羧化效率和饱和光强比展叶红16d的一年生叶高,CO2补偿点和光补偿点比一年生叶低,两者的净光合速率日进程曲线均为“双峰”型,午间胞间CO2浓度上升表明,此时净光合速率下降主要受非气孔限制因素的影响。一年生叶蒸腾速率高于二年生叶,它们日进程曲线为单峰河,午间最高,而气孔阻力进间最低。不同时段作光响应和CO2响应试验表明,上午茶树的表观量子效率,饱和光强和羧化效率较高,光补偿点和CO2补偿点较低。图3表4参26     

Prenatal diagnosis in advanced maternal age. Amniocentesis or CVS,a patient's choice or lack of information?

Ninety-six women of advanced maternal age were interviewed about the way they obtained information on prenatal diagnosis and about how the decision was made as to what procedure was to be performed (transabdominal chorionic villus sampling (TA-CVS) or amnio-centesis). In the CVS group, women visited their physician or midwife earlier in pregnancy (mean 7.1 weeks) than those in the amniocentesis group (mean 10.7 weeks). The availability of prenatal diagnosis was not mentioned during the first antenatal visit in 55 per cent of women from the amniocentesis group as opposed to 25 per cent from the TA-CVS group. Approximately 40 per cent of women eligible for prenatal diagnosis did not receive any information from the referring body prior to counselling at our centre. Only 29 per cent of women who underwent amniocentesis had actually chosen this procedure; 71 per cent were too late to undergo TA-CVS at 12 weeks. It is concluded that information to the patient must be improved in order to ensure early referral for prenatal diagnosis.     

Seasonal variations of monoterpene emissions from coniferous trees of different ages in Korea

Seasonal variations of emission rates and compositions from coniferous species were measured under controlled conditions using a vegetation enclosure method. Total emission rates and compositions of monoterpene compounds from young and adult trees in different seasons were compared.

It was found that the total emission rates and the components of monoterpene varied significantly with tree species, age, and season. Total emissions from C. japonica and P. koraiensis were higher for older trees than for younger trees; however, significantly higher emissions were found from younger trees for C. obtusa. Higher monoterpene emission rates from each plant were found in spring and summer compared with autumn and winter emissions.