Within-population variation in ejaculate characteristics in a prolonged breeder,Peron’s tree frog, <Emphasis Type="Italic">Litoria peronii</Emphasis>

Sperm number is often a good predictor of success in sperm competition; however, it has become increasingly clear that, for some species, variation in probability of paternity cannot be explained by sperm number alone. Intraspecific variation in ejaculate characteristics, such as the number of viable sperm and sperm longevity, may play an equally important role in determining fertilization success. Here, we assess variation among ejaculates in three factors that may contribute to fertilization success (number of sperm per ejaculate, viability, and longevity), in a population of Peron’s tree frog (Litoria peronii). We detected large variation among males in the number of sperm per ejaculate and the proportion of viable sperm within ejaculates, which could not be explained by variation in either male size or body condition. However, the proportion of viable sperm released by males increased over the season. Finally, we assessed sperm longevity (proportion viable sperm determined using a dual-fluorochrome vital dye) at two different temperatures. At 23°C, on average, 75% of sperm remained viable after 2 h, but there were significant differences amongst males with the percentage of viable sperm ranging from 43% to 95%. For sperm incubated at 4°C, ejaculates varied fivefold in sperm longevity with some males having 50% viable sperm after 5 days. Our data suggest that ejaculate characteristics (sperm number, viability, and longevity) vary widely in Peron’s tree frog and may therefore play an important role in determining siring success both in the presence and absence of sperm competition. We discuss the results in relation to selection on ejaculate traits via natural and sexual selection in this and other amphibians.     

基于STIRPAT模型的环境压力空间差异分析——以能源消费为例

定量分析区域人文驱动力对环境的影响,对认识我国区域环境压力及其影响因素具有一定的科学意义.利用STIRPAT模型,以人口数量、富裕度为自变量,以能源消费总量为因变量,应用岭回归函数拟合得到环境压力模型.以研究结果为依据.利用Mapinfo7.0 软件分别绘制人口数量和富裕度对环境压力影响的空间差异图.结果显示,不同省份间人口数量和富裕度对环境压力影响存在显著差异.尽管各省份人口数量对环境压力都产生线性正效应影响,但影响强度有明显差异,最大者是最小者的8.079倍.富裕度对环境压力影响,有正效应或者负效应;有线性作用或者弹性作用.30个考察对象中,北京、上海、四川、新疆4个省市的富裕度二次项系数为负,这说明,在数据观测范围内以上4个省市的结果支持富裕度与环境压力间存在倒"U"型环境库兹涅茨曲线的观点;但这4个省市的环境压力并没有出现下降,这是由于各种人文驱动力影响的净效应决定了环境压力变化趋势.人口数量的增长对环境压力的上升存在较强正效应.因此,控制人口数量的速度对改善环境压力将起到关键作用.     

北京市气溶胶的时间变化与空间分布特征

以MODIS气溶胶遥感数据与同期AERONET监测数据为基础,应用统计分析、对比分析、时间序列分析等技术手段,研究了北京地区气溶胶的时间变化和空间分布特征.结果表明,气溶胶MODIS遥感反演数据和同期AERONET监测数据吻合较好,Pearson积矩相关系数为0 789,误差为ΔAOT550 = -0.077AOT 0.03.北京地区气溶胶550 nm光学厚度AOT和细粒比η的时间变化规律性明显:夏季以城市污染气溶胶为主,光学厚度最高,且具细粒特征;春季城市污染气溶胶和春季沙尘共存,光学厚度比较高,且粗粒占一定比例;冬季以采暖燃煤气溶胶为主,光学厚度不高,但是粗粒占较大比例;秋季大气清澈,气溶胶平均光学厚度仅为0.34.空间分布方面,主要受植被覆盖和产业结构等因素影响,位于西部北部山区的延庆、密云、怀柔和门头沟区气溶胶的光学厚度低,位于东南部平原地区的昌平、顺义、通县、大兴和房山区气溶胶光学厚度总体较高.     

Runoff variation affected by precipitation change and human activity in Hailiutu River basin,China

For recent years, runoff generation and hydrological processes in Hailiutu River basin have been greatly changed by climate change and human activity, especially water and soil conservation construction. In this study, the trends in precipitation, evapotranspiration (ET) and river runoff as well as the effects of precipitation change and human activity on runoff variation have been studied. The results showed that during 1960–2000, annual precipitation and river runoff, monthly precipitation and ET in September and October as well as monthly runoff in all months showed a significant decrease. In addition, peak flow and base flow had a large decrease. Under the joint influence of precipitation change and human activity, the mean annual runoff decreased by 35 million m³ from the baseline period (1960–1985) to the change period (1986–2000), which accounted for 60.9% and 39.1% of the total runoff decrease, respectively. Precipitation change played a primary role in the decrease of annual runoff whereas human activity, particularly water and soil conservation construction, also had remarkable impacts on runoff variation.     

企业粉尘职业危害监督量化分级管理指标体系的筛选

目的是建立粉尘职业卫生监督量化分级管理指标体系,为企业的粉尘职业危害防治提供依据。对象与方法是以59名国内职业卫生领域专家为研究对象。通过编制的调查表,让专家依据各指标的重要程度打分。国内职业卫生领域符合条件的专家以电子邮件方式发送调查问卷70份,收回调查表59份。利用变异系数法,计算每一指标的平均分、变异系数和满分比,评价信度和效度,最终筛选确定粉尘企业职业危害监督量化分级管理的指标体系。结果如下,59名专家积极系数84.3%,8项一级指标和69项二级指标的平均值均超过2.5,变异系数均在50%以下,满分比均介于0-1之间,8项一级指标的克朗巴赫值均大于0.6,相关系数介于0.249-0.705之间。除预防措施和粉尘危害项目存在的问题外,其余均具有统计学意义。结论为企业粉尘职业危害监督量化分级管理指标体系经筛选包括8项一级指标和69项二级指标。     

电袋复合除尘器的设计要点及工程应用

电袋复合除尘器是近年来发展起来的一种新的除尘技术,是在结合电除尘器和袋除尘器这两种传统的高效除尘技术的基础之上发展而来的。本文重点讨论了电袋复合除尘器设计过程中应重点关注的设计要点,并通过成功应用的改造工程实例,介绍了其改造过程和改造效果。     

沙田柚根围AM真菌的生境适宜性和季节变化性

以山地长寿沙田柚成年果树为对象,研究不同生境和季节对丛枝菌根(Arbuscular mycorrhiza,AM)真菌侵染以及根围土壤中AM真菌孢子密度的影响.试验结果表明,不同生境下,菌根侵染率和AM真菌孢子密度都是以梯田最高,坡地次之,洼地最低;在坡地和洼地生境下,生草区均高于清耕区.两块试验地AM真菌的菌丝侵染率均为夏季最高(16.8%±1.9%和16.0%±1.8%),秋季次之,冬季最低;丛枝和泡囊的形成也是夏/秋季较高,春/冬季较低;而根围土壤中AM真菌孢子密度则是秋季最高[(159±19)个/100 g和(167±17)个/100 g],夏季次之,冬季最低.总之,对于长寿沙田柚成年果树,AM真菌的菌根侵染率在夏季梯田最高,根围土壤中的AM真菌孢子密度在秋季梯田最高;在坡地和洼地生境中,生草处理均可显著提高菌根侵染率和AM真菌孢子密度.图4参27     

乌鲁木齐市蔬菜基地土壤有效态镉的空间变异特征

以乌鲁木齐市北郊蔬菜基地为典型区,对干旱区绿洲城市郊区土壤有效态镉含量的结构特征进行分析,得出该区有效态镉的空间分布格局,并揭示了引起这种分布格局的成因和污染来源.结果表明,乌鲁木齐市北郊蔬菜基地有效态镉属中等变异.半方差函数模型拟合表明,有效态镉含量可以用指数函数拟合,且在一定范围内存在空间相关性.采用Kriging...     

Archimedean Copulas在降水变异概率分布特征研究中的应用——以新疆福海县为例

探究二维情况下变异不同步,也就是一个变量发生变异,而另一个变量不发生变异的情况,对Copula联合分布的影响.在气温变化的环境下,降水过程发生了显著变异,而年降水量和年总降水天数的联合分布对长期旱涝情况有重要意义.以Copula函数为基础,计算新疆福海站年降水量和年总降水天数联合分布,用传统变异分析方法进行变异分析.针...     

北京市PM2.5水分含量及其变化特征

利用卡尔费休法可直接测定PM_2.5水分含量,方法精密度及准确度均较好.将该方法应用于北京市城区站点2020年全年的PM_2.5分析,结果显示PM_2.5水分浓度年均值为(5.0±4.1)µg/m³,在PM_2.5占比为(12.5±4.8)%,与PM_2.5质量浓度呈显著相关.水分质量浓度与PM_2.5的质量浓度月度及季节变化趋势基本一致.研究发现,随着空气污染加重,水分质量浓度及其在PM_2.5占比均呈上升趋势,二者相关性明显增强.可见污染发生时,水分增加有利于颗粒物吸湿增长从而推高污染水平,对PM_2.5的贡献同步增强.当沙尘污染发生时湿度处于同期较低水平,不利于细颗粒物的吸湿增长,水分质量浓度及其占比均处于较低水平. PM_2.5水分与二次离子及有机物均有很好的相关性,说明水分为气态污染物提供非均相转化载体,促进硝酸盐、硫酸盐、有机物的进一步生成.PM_2.5水分与地壳物质无相关性,证实地壳元素为一次源,不受水分影响.