906 resultados para Intraclonal division of labor


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The purpose of this research is to identify the impact of recent organizational change upon the culture of firefighting. The experiences of female firefighters were utilized as a measure of cultural change. A purposive sample of twenty-seven male and female firefighters were interviewed in a semi-structured format about their experiences in the fire service. This research found that the culture of firefighting has adjusted to the presence of previously excluded groups by forging a division among the identities and roles of male and female firefighters. The white, male firefighters, who have traditionally constituted a majority of the workforce, have continued to identify with traditional firefighter roles and reported high levels of cohesion. In contrast, the female firefighters showed a greater variance in their identification with traditional roles and decreased levels of cohesion with the main body of the group.

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In 1917 the Board was succeeded by the Division of labor statistics of the Department of labor.

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Description based on: 1969.

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时空异质性是生境的基本特征。几乎所有植物都是在一定尺度的时空异质性环境中完成其生活史的。在进化过程中,植物可能形成了各种有效利用环境异质性的生态适应对策。克隆生长使得克隆植物在理论上更容易适应于异质性环境。本文以匍匐茎和根状茎型草本为材料,应用实验生态学方法研究了游击型克隆植物对异质性环境的生态适应对策。 在沙丘生境(如毛乌素沙地)中,沙埋是植物常常遭遇的事件。由于沙埋在水平空间表现出非均匀性,克隆植物的基株或克隆片断常常经历局部沙埋。通过温室和野外实验,研究了克隆整合作用对鹅绒委陵菜和沙鞭沙埋分株忍受沙埋能力的影响。结果表明,克隆整合显著提高鹅绒委陵菜和沙鞭沙埋分株的存活。进一步的耗-益分析表明,克隆整合使鹅绒委陵菜沙埋分株显著受益,而对非沙埋分株却没有显著耗损,故整个克隆片断的生长得到显著提高。因此,克隆整合是沙丘生境中克隆植物对局部沙埋胁迫的生态适应对策之一。 通过2个温室实验,研究了金戴戴对光照、基质养分和盐分的克隆可塑性。结果表明:光照强度、基质养分和盐分对金戴戴克隆生长和克隆形态均有十分显著的影响。深度遮光、低养和高盐均显著削弱金戴戴的生长,其生物量、叶面积、分株数、匍匐茎长及叶柄长和根冠比对基质盐分的可塑性大小和格局显示出基株间的差异。在低养分条件下,金戴戴匍匐茎节间显著伸长,而分枝强度显著减弱。这些结果与克隆植物觅食模型相符合,表明当生长于异质性环境,金戴戴可凭借克隆可塑性实现的觅养行为来增加对养分资源的摄取。因此,克隆可塑性是克隆植物利用环境异质性的另一条途径。 在另一温室实验中,研究了三种匍匐茎克隆草本鹅绒委陵菜、金戴戴和绢毛匍匐委陵菜对光照和养分资源交互斑块性环境的反应。当置于高光低养下的分株与低光高养下的分株相连时,高光低养分株、低光高养分株以及克隆片断的生物量均得到显著提高。同时,低光高养下分株的根冠比相对增加,而高光低养下分株的根冠比相对下降。这表明,三种克隆植物发生了环境诱导的克隆内分工行为。这种环境诱导的克隆内分工行为有利于整个基株对资源交互斑块性环境的利用,是克隆植物对异质性环境的生态适应对策。

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No more published?

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Mode of access: Internet.

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Shipping list no.: 97-0328-P.

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Vols. for 1869/70-1871/72 issued as documents of the Senate of the General Court of Massachusetts, no. 120, 150, 180; 1872/73 as document of the House of Representatives of the General Court of Massachusetts, no. 173; 1873/74-1878/79 as Massachusetts Public document no. 31; 1879/80- as Public document.