Host-size-dependent sex ratio in a parasitoid wasp

Charnov's host-size model explains parasitoid host-size-dependent sex ratio as an adaptive consequence when there is a differential effect of host size on the offspring fitness of parasitoid males versus females. This article tests the predictions and the assumptions of the host-size model. The parasitoid wasp Pimpla nipponica Uchida (Hymenoptera: Ichneumonidae) laid more female eggs in larger or fresher host pupae when choice among hosts of different sizes or ages was allowed. Then, whether an asymmetrical effect of host size and age on the fitness of females versus males existed in P. nipponica was examined. Larger or fresher host pupae yielded larger wasps. Larger females lived longer, whereas male size did not influence male longevity. Large males mated successfully with relatively large females but failed with small females, whereas small males could mate successfully either with small or with large females. Thus, small-male advantages were found, and this held true even under male–male competition. Ovariole and egg numbers at any one time did not differ among females of different sizes. Larger females attained higher oviposition success and spent less time and energy for oviposition in hosts. Larger females produced more eggs from a single host meal. Taken together, females gained more, and males lost more, by being large. Host size and age thus asymmetrically affected the fitness of offspring males versus females through the relationships between host size or hast age and wasp size, which means the basic assumption of the host-size model was satisfied. Therefore, sex ratio control by P. nipponica in response to host size and age is adaptive. Received: November 13, 1998 / Accepted: January 18, 1999     

战略实施与企业绩效:项目管理机制的中介效应

项目管理理论认为,战略可以通过项目管理机制得以实施,但多数文献对项目管理机制在业务战略和企业绩效之间的作用机理缺乏系统的研究.本研究把"项目管理办公室"、"项目群管理"、"阶段门审查"等项目管理机制作为中介变量.引入到业务战略对企业绩效的影响过程中.研究发现,三种项目管理机制都对低成本战略一企业绩效有显著的中介效应,项目管理办公室对差异化战略一企业绩效有显著的中介效应,从而证实了项目管理机制在不同程度上可以作为战略实施的有效方式.     

市政建设项目社会效益和环境效益经济评价的实例研究

市政建设项目的直接经济效益往往很小 ,其主要效果表现为社会效益和环境效益等无形效益。目前 ,使用货币单位估价无形效果的方法 ,仍处于研究探索阶段。以南京地铁南北线一期工程为实例 ,提出了社会效益和环境效益定量化和货币化的方法 ,并进行了详细的经济评价     

全项目实战型实践教学模式在社会工作人才培养中的开发与应用

为更好提升社会工作人才职业性、专业性的素质要求,切实解决在专业人才培养过程中的实际问题,契合社会工作专业人才市场发展趋势的内在要求,从服务区域经济社会发展需求出发,贯穿于理论讲授、实习实践,毕业设计各环节,探索教师、学生和服务机构工作人员共同参与的"全项目全过程实战实践教学模式",从理论课程教学设计、实践课程教学设计、专业教师的督导制度、实习实训基地建设、社会服务项目实战等教学实践环节全面实施,明显提升学生专业视野、专业认知、专业技能等,教师的教学能力与科研水平在项目实践中得到了提高,项得到了实习机构的高度认可,打开了就业市场,赢得了就业单位的好评。     

Information Systems Project Continuation in Escalation Situations: A Real Options Model

Software project escalation has been shown to be a widespread phenomenon. With few exceptions, prior research has portrayed escalation as an irrational decision‐making process whereby additional resources are plowed into a failing project. In this article, we examine the possibility that in some cases managers escalate their commitment not because they are acting irrationally, but rather as a rational response to real options that may be embedded in a project. A project embeds real options when managers have the opportunity but not the obligation to adjust the future direction of the project in response to external or internal events. Examples include deferring the project, switching the project to serve a different purpose, changing the scale of the project, implementing it in incremental stages, abandoning the project, or using the project as a platform for future growth opportunities. Although real options can represent a substantial portion of a project's value, they rarely enter into a project's formal justification process in the traditional quantitative discounted cash‐flow‐based project valuation techniques. Using experimental data collected from managers in 123 firms, we demonstrate that managers recognize and value the presence of real options. We also assess the relative importance that managers ascribe to each type of real option, showing that growth options are more highly valued than operational options. Finally, we demonstrate that the influence of the options on project continuation decisions is largely mediated by the perceived value that they add. Implications for both theory and practice are discussed.     

五行理论与《喜福会》的成功

美国华人作家谭恩美因其第一部小说《喜福会》走红而一夜成名。谭恩美之所以成功,部分原因要归结于她在小说中对中国传统文化要素之一的五行理论的生动描述。     

高职院校实施教学质量工程的探索与实践

本文以我院实施＂教学质量工程＂为主线,以制定人才培养方案为逻辑起点,通过在校企合作、工学结合、师资队伍建设、专业建设、课程和教材建设、实践教学体系建设、共享型教学资源库建设和校园文化建设等方面所进行的探索与实践,有效地提升了人才培养质量,提高了毕业生就业工作水平,充分发挥了作为＂国家示范性高职院校＂立项建设单位服务区域经济建设和社会发展,为我国尤其是西部地区装备制造业培养更多高素质技能型人才的作用。     

高校公共体育课引入Project Adventure的探讨

心理健康、社会适应能力健康、身体健康与道德健康一起构成了人类健康的共同要素。本研究通过文献资料调研、动态性现场实验等方法,对高校体育课程中运用Project Adventure体育教育模式的可行性和必要性进行了分析,试图将目前成功应用于社会培训业的Project Adventure引入高校,通过新的整合,以此来探索高校对大学生进行心理健康教育和社会适应能力培养的新途径,表明了高校引入Project Adventure的意义和内涵,并提出了高校开设体育Project Adventure课的实施对策。     

“三个代表”是检验党的全部工作得失成败的根本标准

“三个代表”是对实践标准、生产力标准和“三个有利于”标准的继承和发展 ,是衡量党的全部工作得失成败的科学尺度和价值尺度 ,用“三个代表”检验党的全部工作具有全面性、过程性、直观现实性等鲜明特点。总之 ,“三个代表”是检验党的全部工作得失成败的根本标准     

民间文学普查的基础问题

根据文化部民族民间文化遗产保护工程的要求和十部中国民间文艺集成志书工作基础,提出需要完成民间文学普查项目13项意见。最核心的要求是普查中要注意"立体描写","全面","立体的全面的科学记录"。不仅要深入民间,抢救保护老歌手、老故事家、老戏曲、曲艺艺人和老演员及其保存的口传的作品,也要抢救保护十套集成志书普查时已经采录到手的资料和老文化工作者、老专家学者及其学术积累的资料。建立民间文化资料馆。保护和抢救要统一起来。