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81.
82.
Ingrid born Anna-Karin Modin-Edman Helena Bengtsson Gunnela M. Gustafson Eva Salomon S.Ingvar Nilsson Johan Holmqvist Simon Jonsson Harald Sverdrup 《Ambio-人类环境杂志》2005,34(4)
通过把全面的农田试验和矿质风化释放养分以及微量元素循环具体研究结合起来,用一个系统分析方法来评价农场尺度上的养分和微量元素可持续性.为了比较有机和常规农业管理方式,在瑞典北部的Ojebyn奶牛场进行了一个包括磷、钾和锌在内的农场尺度上的实例研究.通过结合不同的元素平衡法(农场总体尺度、畜舍尺度和农田尺度)以及进一步把这些方法应用到FARMFLOw模型,我们能够把子系统内质量流和库结合起来并建立子系统之间联系,来进行农场尺度上的预测.研究发现农场内部的元素流动大,而且农场有内部源(锌)和损失项(钾).在Ojebyn奶牛场形成并得到验证的方法是很有前途的,认为可以应用到任何农场. 相似文献
83.
The advantages of a routine screening or indication-based ultrasound investigation during pregnancy are still under debate. This is the first study where both methods are compared in two different time periods. More malformations were diagnosed before the 24th week of gestation by means of screening-based than indication-based investigation (18 per cent vs. 5 per cent, P<0·005), and before 28 weeks in 26 per cent compared with 15 per cent respectively (P<0·01). Twenty-six per cent of all malformations were detected by means of screening-based investigations as opposed to 15 per cent by means of indication-based scans. Primary fetal malformations were also diagnosed much earlier (25 weeks vs. 30 weeks). Except for the fetal head, the detection rate of malformations was higher in nearly all other body regions of the fetus in the screening-based investigation. The most important advantage of a screening-based ultrasound investigation during pregnancy is to detect the malformations early enough in pregnancy for possible intrauterine treatment or to offer safe termination of pregnancy for the woman, at least for those anomalies that are lethal or significantly handicapping. 相似文献
84.
85.
Ingrid Bouwer Utne 《Journal of Cleaner Production》2009,17(3):335-344
Systems engineering principles in fisheries management may structure and improve the decision-making process. Sustainability in the fishing fleet is comprised of economic, environmental, and social dimensions. Even though the total system value may be constituted by economic factors and technical factors, non-market issues, such as environmental and social issues, have an increasingly important impact on the economic performance of a system or company. Life cycle cost (LCC) is related to the systems engineering process, because economic considerations are very important in the process of creating systems. LCC involves evaluation of all future costs related to the life cycle of a system. The main objective of this article is to discuss the usefulness of LCC as a method to enhance sustainable designs of fishing vessels for ship owners, and to improve the decision-bases for fisheries management. 相似文献
86.
An important policy question receiving considerable attention concerns the risk perception–risk mitigation process that guides how individuals choose to address natural hazard risks. This question is considered in the context of wildfire. We analyze the factors that influence risk reduction behaviors by homeowners living in the wildland–urban interface. The factors considered are direct experience, knowledge of wildfire risk, locus of responsibility, fulltime/seasonal status, and self-efficacy. Survey data from three homeowner associations in the western U.S. are used to estimate the direct and indirect effects of this relationship. Our results indicate that the effects of knowledge and locus of responsibility are mediated by homeowners' risk perceptions. We also find that beliefs of self-efficacy and fulltime/seasonal status have a direct influence on risk reduction behaviors. Finally, we find, surprisingly, that direct experience with wildfire does not directly influence the risk perception–risk mitigation process. 相似文献
87.
Ingrid Strid Eriksson Helena Elmquist Thomas Nybrant 《Ambio-人类环境杂志》2005,34(4):382-386
农业生产系统的生态可持续性评估亟需一些有效工具.本文所描述的SALSA(可持续农业系统分析,Systems Analysis forSustainable Agriculture)是一种环境系统分析工具.它由各种物流模型构成,并运用生命周期评价法阐释模拟结果.SALSA的一个示范性应用案例就是3种不同的生猪养殖情景在各自能源投入以及对全球变暖、富营养化和酸化作用方面的环境影响的比较分析.其中综合了不含大豆粉的低蛋白食料、改良后的肥料管理技术、低氮损失的情景是全部影响分类研究中的最佳选择.SALSA模型的优势在于它捕捉不同管理选择的后果的能力,这些管理选择对一个农场的一些过程有某种影响.这也使得文中描述的复杂研究成为可能. 相似文献
88.
89.
Ingrid Ahnesjö 《Behavioral ecology and sociobiology》1996,38(3):167-172
Embryo success was studied in the paternally brooding pipefish Syngnathus typhle. During brooding, which lasts about a month, males provide embryos in their brood pouch with nutrients and oxygen via a placenta-like
structure. Egg size depends on female size. In aquaria, males were mated with differently sized females to give the following
treatments: M, mixed-egg-size broods of approximately half large and half small eggs; L, single-egg-size broods of large eggs;
S, single-egg-size broods of small eggs; and F, field mated males. All males were kept in aquaria for a full brooding period.
For each egg-size category, the number of newborn was compared with the number of eggs the male initially fertilized in his
brood pouch. Within mixed-egg-size broods, a higher proportion of large eggs survived and large eggs resulted in heavier newborn
than small eggs. Indeed, small eggs from a mixed-egg-size brood had significantly lower relative success (proportion of embryos
surviving to birth) than those from a brood entirely composed of small eggs. The implication is that embryos compete for resources
within the brood pouch, and that competitive success depends on egg size. Given that females produce eggs corresponding in
size to their body size, and that females are known to compete indirectly for access to mates (i.e., the sex-roles are reversed),
this intrabrood competition could be seen as an extension of female-female competition, but alternative explanations are discussed.
Received: 28 April 1995/Accepted after revision: 28 October 1995 相似文献
90.
Kenyon?B.?MobleyEmail author Charlotta?Kvarnemo Ingrid?Ahnesj? Charlyn?Partridge Anders?Berglund Adam?G.?Jones 《Behavioral ecology and sociobiology》2011,65(6):1169-1177
The occurrence of male pregnancy in the family Syngnathidae (seahorses, pipefishes, and sea dragons) provides an exceptionally
fertile system in which to investigate issues related to the evolution of parental care. Here, we take advantage of this unique
reproductive system to study the influence of maternal body size on embryo survivorship in the brood pouches of pregnant males
of the broad-nosed pipefish, Syngnathus typhle. Males were mated with either two large females, two small females, a large then a small female, or a small then a large
female. Our results show that offspring survivorship depends on an interaction between female body size and the number of
eggs transferred by the female. Eggs of larger females deposited in large numbers are more likely to result in viable offspring
than eggs of smaller females laid in large numbers. However, when females deposited smaller numbers of eggs, the eggs from
smaller females were more likely to produce viable offspring compared to those from larger females. We found no evidence that
this result was based on mating order, the relative sizes of competing females, or egg characteristics such as dry weight
of eggs. Additionally, male body size did not significantly influence the survivorship of offspring during brooding. Our results
suggest that the factors underlying offspring survivorship in pipefish may be more complex than previously believed, with
multiple factors interacting to determine the fitness of individual offspring within the broods of pregnant males. 相似文献