Sperm precedence, mating interval, and a novel mechanism of paternity bias in a beetle (Tenebrio molitor L.)

When females mate with more than one male, the ensuing sperm competition leads to the evolution of male mechanisms that skew paternity. Males of the yellow mealworm beetle (Tenebrio molitor) transfer a spermatophore to females during copulation, but sperm release and storage occur later. We investigated how the interval between two matings with different males affects sperm precedence by varying the interval between the copulations so that the second mating was either: (1) before sperm release from the first spermatophore (<5 min); (2) after sperm release but before spermatophore ejection (15–20 min); (3) after spermatophore ejection but before sperm storage (4 h), or (4) after complete sperm storage (24 h). We collected offspring over a period of 2 weeks and determined paternity by protein electrophoresis. There was second-male sperm precedence in all treatments, but when the interval was <5 min, the second male usually (86% of cases) had complete sperm precedence (i.e., P ₂=1). Investigations into the mechanism of second-male sperm precedence during <5-min mating intervals indicate that sperm release from the first spermatophore is inhibited, a phenomenon which has not been previously documented. Received: 31 January 2000 / Revised: 9 June 2000 / Accepted: 26 August 2000     

压力管道施工、检验和使用管理环节的探讨

本文以压力管道相关规范和日常工作实际为基础,对压力管道定义进行剖析,着重从使用单位角度上讨论了压力管道施工、检验和使用管理环节需要了解和注意的问题.通过本文对压力管道各管理环节的阐述,表明了压力管道管理的重要性,它需要各岗位人员意识到压力管道管理方面所承担的责任,需要各部门各岗位通力合作,通过过程管理实现本质安全.     

曳引式电梯补偿链长度的检验

本文通过电梯补偿链过长过短影响电梯正常检验和使用的实例,阐述电梯补偿链固定点在电梯运行使用过程中存在空间位置的变化的原因,强调电梯补偿链长度在检验中应注意的事项。     

Control strategies for vehicular NOx emissions in Guangzhou, China

Guangzhou is a city in southern China that has experienced very rapid economic development in recent years. The city's air has very high concentrations of various pollutants, including sulphur dioxide (SO₂), oxides of nitrogen (NOx), ozone (O₃) and particulate. This paper reviews the changes in air quality in the city over the past 15 years, and notes that a serious vehicular-related emissions problem has been superimposed on the traditional coal-burning problem evident in most Chinese cities. As NOx concentrations have increased, oxidants and photochemical smog now interact with the traditional SO₂ and particulate pollutants, leading to increased health risks and other environmental concerns.
Any responsible NOx control strategy for the city must include vehicle emission control measures. This paper reviews control strategies designed to abate vehicle emissions to fulfill the city's air quality improvement target in 2010. A cost-effectiveness analysis suggests that, while NOx emission control is expensive, vehicular emission standards could achieve a relatively sizable emissions reduction at reasonable cost. To achieve the 2010 air quality target of NOx, advanced implementation of EURO3 standards is recommended, substituting for the EURO2 currently envisioned in the national regulations. Related technical options, including fuel quality improvements and inspection/maintenance (I/M) upgrades (ASM or IM240), are assessed as well.     

主动为环境监督管理服务

分析了一些县级监测站存在的只注重监测数据，缺乏主动为环境管理服务的思想，介绍了海门市则站主动为环境管理及时提供的监测数据，促进了环境监督管理。     

浅谈环境风险防范现场检查与验收

简述了环境风险防范现场检查与验收的主要内容,对在环境影响评价及批复、环境监理、事故应急水池、报警和监控设备、环境与安全风险之间的关系、竣工环境保护验收技术规范等方面存在的问题进行了分析,提出了相应建议。     

中原城市群水环境指标体系监测及改进对策

对中原城市群供排水环境指标进行了检测和分析,其中包括供水水质标准、污水排放水质标准、回用水水质指标、水环境质量标准等.其次,将各类水质检测结果与有关国家或行业标准对比分析,提出了中原城市群水环境质量标准中存在的问题.最后,提出了改善中原城市群水环境质量标准措施.研究成果对于提高各类水质监测技术水平和方法,改善水环境质量,实现中原城市群水务标准化管理等具有参考意义.     

谈水污染治理设施运行的监督管理

就目前水污染治理设施运行中存在的问题，提出了对策和建议。指出，只有加强全方位的监督管理，才能确保水污染治理设施和正常运行。