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131.
Male competition in Cardiocondyla ants 总被引:3,自引:0,他引:3
The two types of males in the ant genus Cardiocondyla differ remarkably in morphology and behavior. Ergatoid males are wingless fighters whose spermatogenesis continues throughout
their entire adult lives and which therefore have an “unlimited” sperm supply. They attempt to kill all eclosing ergatoid
rivals and thus to increase their share in copulations with the virgin queens reared in their nests. Winged males, on the
other hand, are docile and emigrate from the nests a few days after eclosion, probably to mate with queens from other colonies.
By this time, their testes have fully degenerated and all sperm is stored in the seminal vesicles. Before emigration, winged
males may mate with virgin queens in their maternal nests, but they are nevertheless rarely attacked by ergatoid males. In
the laboratory, the life expectancy of ergatoid males is only slightly higher than that of winged males, but because of the
emigration of the latter the difference is likely to be more pronounced in the field. Both male morphs are capable of inseminating
more than 35 virgin queens. However, winged males older than 14 days mate less often than ergatoid males of similar age, probably
due to sperm depletion in later life. The spermathecae of queens inseminated by ergatoid males contained significantly more
sperm than those of queens which mated with winged males. We discuss the evolution of intranidal mating and male polymorphism
in ants.
Received: 8 August 1997 / Accepted after revision: 6 October 1997 相似文献
132.
Current organizational theory and research affirm the beneficial effects of experiencing positive affect at work. In recent years, researchers have begun to question the popular notion that the more positive affect at work, the better—that more positive affect is desirable for work‐related outcomes. In this article, we propose a rationale for why more positive affect may not be better for proactive behaviors at work. Findings from two field studies using two unique data sources demonstrate support for our hypothesis, suggesting that intermediate levels of positive affect are most beneficial for proactive behaviors. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
133.
This study compared the actual and perceived social norms regarding road crossing behaviors, and aimed at uncovering a misperception of group norms. The basic notion underlying the study was that if children perceived the behaviors and attitudes of their friends regarding road crossing as more negative than they actually are, this might lead the children to adopt riskier behavior when crossing the road. The participants were comprised of 123 elementary school children (ages from 6 to 13; 78 boys - 65% and 42 girls - 35%) from Beitar-Ilit, a religious city in Israel. A questionnaire especially constructed for the study was administered to the participants. A t-test yielded a significant difference between the child’s own attitudes score and the perceived peers’ attitudes score. On average, children perceive their friends’ attitudes with regard to road crossing behaviors as being more negative compared to their own attitudes. A second t-test yielded a significant difference between the child’s own behavior score and the perceived peers’ behavior score. Children perceived the road crossing behavior of their friends as riskier relative to their own crossing behavior. A regression test revealed that the variables, perceived peers’ attitudes and perceived peers’ behaviors, contributed significantly to the explained variance: the more risky the perceived peers’ attitudes and behaviors with regard to road crossing, the more risky the child’s own behavior when crossing the road. It is hoped that an interventional educational program based on positive norms in the social group will encourage children to exhibit safe behavior in the roads. 相似文献
134.
大采高综采技术是厚煤层开采工艺的重要发展方向,越来越多的被采用,矿压事故在矿山生产安全事故中占有较大比例,有效掌握矿压规律,采用合理生产工艺是采矿生产过程中必须认真考虑的问题。大采高综采工作面采场顶板跨度大、高度高,矿山压力复杂,矿压显现规律特殊,管理难度大。针对某煤矿9、10号煤层大采高综采工作面顶板坚硬特性,为掌握类似地质条件下大采高工作面矿压显现规律,作者从理论分析入手,采用相似模拟实验方法,经过对模拟实验数据进行研究分析,得出了本矿区特定坚硬顶板条件下大采高工作面矿压显现规律,认为类似地质条件大采高工作面,顶板垮落易造成动力冲击,顶板破坏形式主要是拉断和剪断,最大压力值发生在工作面中部前方,采空区积水的影响情况和地表的沉陷状况,还需通过其他方法进行进一步的分析、论证,提出了针对类似围岩条件采煤工作面的安全技术和管理措施。 相似文献
135.
基于人工社会模型的退田还湖生态补偿机制实例研究 总被引:7,自引:0,他引:7
基于补偿者和受偿者意愿的研究方法是建立切实可行的生态补偿机制的有效手段。为探讨在我国许多地区开展退田还湖生态补偿政策的有效实施机制,减少洪涝灾害与生态环境退化负面效应,研究构建了基于农户、政府和企业三类主体及其相互作用的生态补偿模型,并重点分析生态补偿标准、洪灾风险、生态环境保护、劳动力本地转移政策等因素对农户主体土地利用决策的影响。以鄱阳湖区莲湖乡为实例,以农户和企业从事生产活动的行为特征和政府宏观调控方式为基本准则,利用构建的多主体模型模拟了不同补偿机制下退田还湖政策可能产生的土地利用长期效应。结果表明,政府给予农户的经济补偿可以使农户自愿实施退田,但在不同情景下,政府实施退田还湖的代价和达到预期目标的时限差距显著。企业参与不仅能减轻政府的经济负担,同时也有利于剩余农村劳动力的转移。政府发展壮大当地经济,提高农业劳动力向非农产业转移的速度和质量,均有助于推进退田还湖政策的有效实施。 相似文献
136.
Significant quantities of wastes are generated as the waste materials or byproducts every day from stainless steel processes. According to the origins and characteristics, the stainless steel wastes can be mainly classified into two categories, slags and dusts. They usually contained considerable quantities of valuable metals and materials. This paper summarized and analyzed the generation, composition, characteristics and the leaching behaviors of the most of wastes obtained from the stainless steel processes. On this basis, a review of several methods for treating the various stainless steel wastes was made. It is very essential not only for recycling the valuable metals and mineral resources but also for protecting the environment. 相似文献
137.
138.
Devising effective strategies to facilitate waste reuse depends on the solid understanding of reuse behaviors. However, previous studies of reuse behavior have been limited in scope, focusing mostly on household recycling behaviors or very limited types of industrial wastes. To gain a better understanding of the business reuse behaviors, this study examined the impact of various factors in technical, economic, regulatory, and behavioral categories in the case of coal ash generated in the United States. The results of fixed effect models for fly ash and bottom ash particularly showed the significance role of the behavioral factor. In both models, a proxy variable, which represents knowledge sharing among the power plants or the utility's decision-making, turned out to be statistically significant and had the largest coefficient estimates among a group of variables. This finding may imply that the characteristics of waste reuse behavior are determined more by business decision-making behaviors than by market or institutional factors. However, the role of the behavioral variable was stronger in the bottom ash models than in the fly ash models. While the reuse of bottom ash was determined primarily by the behavioral variable, fly ash reuse was determined by more diverse factors including economic and regulatory variables. This could be explained by material characteristics in relation to competing resources and the nature of reuse applications. 相似文献
139.
有效防治工业污染、改善环境是工业企业的基本责任。以能够反映企业环境行为的信息为基础,通过建立科学的百分制量化评价体系,对H省具有代表性和典型性的重点排污工业企业的环境守法行为、企业污染控制行为、环境信息公开行为等环境行为进行评价。分析结果表明,该省企业环境行为有较大提升空间,重污染行业形势令人担忧,由此明确企业改善环境行为的关键因素和影响机制,并从企业、政府、社会三个角度提出措施改善企业环境行为的建议。 相似文献
140.