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221.
Scientific assessments of environmental problems, and policy responses to those problems, involve uncertainties of many sorts. Meanwhile, potential impacts of wrong decisions can be far-reaching. This article explores views on uncertainty and uncertainty communication in the Dutch science-policy interface and studies several issues concerning presentation of uncertainty information. Respondents considered uncertainty communication to be important, but it should be concise and policy relevant. Several factors influence policy relevance, including the place of an issue in the policy cycle, and its novelty, topicality and controversiality. Respondents held particular interest in explicit communication on the implications of uncertainty. Related to this, they appreciated information on different sources and types of uncertainty and qualitative aspects of uncertainty (e.g. pedigree charts). The article also studies probability terms, particularly for IPCC's 33–66% probability interval (‘about as likely as not’). Several terms worked reasonably well, with a median interpretation of 40–60%. Finally, as various target groups have different information needs and different amounts of attention for various parts of a report or communication process, it is important to progressively disclose uncertainty information throughout the communication. Improved communication of uncertainty information leads to a deeper understanding and increased awareness of the phenomenon of uncertainty and its policy implications.  相似文献   
222.
Distinct acoustic whistles are associated with the wing-beats of many doves, and are especially noticeable when doves ascend from the ground when startled. I thus hypothesized that these sounds may be used by flock-mates as cues of potential danger. To test this hypothesis, I compared the responses of mourning doves (Zenaida macroura), northern cardinals (Cardinalis cardinalis), and house sparrows (Passer domesticus) to audio playbacks of dove ‘startle wing-whistles’, cardinal alarm calls, dove ‘nonstartle wing-whistles’, and sparrow ‘social chatter’. Following playbacks of startle wing-whistles and alarm calls, conspecifics and heterospecifics startled and increased vigilance more than after playbacks of other sounds. Also, the latency to return to feeding was greater following playbacks of startle wing-whistles and alarm calls than following playbacks of other sounds. These results suggest that both conspecifics and heterospecifics may attend to dove wing-whistles in decisions related to antipredator behaviors. Whether the sounds of dove wing-whistles are intentionally produced signals warrants further testing.  相似文献   
223.
杨强  胡磬遥  黄成  陈昀  刘佳栋  李莉  熊忠亮  唐伟 《环境科学》2018,39(10):4463-4471
SCR技术是降低包括常规、混合动力公交车在内的重型柴油车NO_x排放的重要手段.基于无线远程通讯技术,对杭州市秋冬季11辆实际运行的混合动力公交车SCR系统的运行和NO_x排放特性进行了研究.分别研究了混合动力公交车内燃机模式下车速及发动机运行工况和环境温度对SCR催化器后温度、尿素喷射量和SCR催化器后NO_x排放浓度的影响.结果表明,安装有SCR系统的混合动力公交车有(32.4±4)%的运行时间处于内燃机模式下,模式下平均有(26.9±11)%的运行时间SCR没有工作;SCR系统正常工作的混合动力公交车的NO_x平均减排率约为59%;SCR系统未达到运行要求而不工作和SCR催化器低温转化效率低是造成公交车NO_x排放较高的主要原因;当车速高于40 km·h-1时,SCR催化器后温度上升至230℃以上,SCR系统的工作比例和尿素喷射量上升的同时NO_x排放大幅下降;进入冬季,随着环境温度的降低,混合动力公交车SCR催化器出口温度降低的同时,平均尿素喷射量降低导致NO_x排放恶化.  相似文献   
224.
目的为提升战场电磁环境环境复杂度评估的客观性,基于电磁环境与通信性能的相关性提出一种电磁环境复杂度评估方法。方法该方法以层次分析法和混合加权理论为基础,以典型通信系统为例,建立语音通信和数据通信设备性能和电磁环境复杂度等级的映射,并据此建立通信网系性能和电磁环境复杂度的等级映射,从目标层、准则层、指标层给出五级量化指标体系。结果在50 km×50 km典型地域中,上述评估方法给出了10部高频和10部超高频通信设备组成的通信网络各单链路通信质量,分别为Ⅳ、Ⅳ、Ⅰ、Ⅳ、Ⅲ、Ⅱ、Ⅳ、Ⅴ、Ⅳ、Ⅲ、Ⅱ、Ⅱ、Ⅲ、Ⅴ、Ⅱ、Ⅰ、Ⅴ、Ⅳ、Ⅴ、Ⅴ,并在此基础上评估了整个网系的通信质量等级和整个通信网系面临的电磁环境复杂度(Ⅳ)。结论上述研究验证了方法的可行性,同时证实了同一环境下不同设备所受的电磁环境影响具有个体差异性,整体通信网系的受影响程度有别于单一设备。研究结果可为通信网系的电磁环境适应性试验、电磁干扰效应评估等研究提供基础和有益的参考。  相似文献   
225.
/ In modern intensive animal farming the disposal of a large amount of waste is of great concern, as, if not properly performed, it can cause the pollution of water, mainly because of the high content of nitrate and phosphate. This paper presents the results of a study intended to assess the environmental sustainability of animal waste disposal on agricultural soils in the alluvial plain of the River Chiana (Tuscany, Italy), a particularly sensitive area because of the high vulnerability of the shallow aquifer and of the intensive agricultural and breeding activities. With this aim, a strategy has been employed, that consists of the integrated use of a management model and GISs. The consequences on groundwater of applying animal waste to different kind of soils and crop arrangements have been simulated by means of the management model GLEAMS (Groundwater Loading Effects of Agricultural Management Systems, ver 2.01). As the huge amount of data required by such a sophisticated model does not allow applications at a scale larger than the field size, IDRISI and GRASS GIS packages have been used to divide the study area into land units, with homogeneous environmental characteristics, and then to generalize on these units the outputs of the model. The main conclusions can be synthesized as follows: The amount of animal waste produced in some of the investigated areas (i.e., municipal territory) is greater than that disposable on their own agricultural soil with no risks to the groundwater; consequently a cooperative approach among municipalities is necessary in order to plan waste disposal in a comprehensive and centralized way.KEY WORDS: Land use; Animal waste disposal; Groundwater protection; GIS, Management models  相似文献   
226.
The function of the vibration signal of the honey bee (Apis mellifera) during house hunting was investigated by removing vibrating bees from swarms and examining the effects on waggle dancing for nest sites, liftoff preparations and swarm movement. We compared house hunting among three swarm types: (1) test swarms (from which vibrating bees were removed), (2) manipulated control (MC) swarms (from which randomly selected workers and some waggle dancers were removed), and (3) unmanipulated control (UC) swarms (from which no bees were removed). The removal of vibrating bees had pronounced effects on liftoff preparations and swarm movement. Compared to the MC and UC swarms, the test swarms had significantly greater liftoff-preparation periods, were more likely to abort liftoff attempts, and in some cases were unable to move to the chosen site after the swarm became airborne. However, the three swarm types did not differ in overall levels of waggle dance activity, the time required to achieve consensus for a nest site, the rate at which new waggle dancers were recruited for the chosen site, or the ability to maintain levels of worker piping necessary to prepare for flight. The removal of vibrating bees may therefore have altered liftoff behavior because of a direct effect on vibration signal activity. A primary function of the signal during house hunting may be to generate a level of activity in workers that enhances and coordinates responses to other signals that stimulate departure and movement to a new location.Communicated by R. Page  相似文献   
227.
Some sexual selection models envisage exaggerated male secondary sexual characters to be costly and therefore reliable indicators of the quality of potential mates to choosy females. If male secondary sexual characters have a natural selection cost, they may be linked to each other by reciprocally constraining relationships that would prevent individual males from increasing their level of multiple signaling. Barn swallow (Hirundo rustica) males have at least two costly signals relevant to socio-sexual interactions: tail length and song. Under the hypothesis that a trade-off exists between male signals, we manipulated the maintenance cost of tail ornaments to test whether this reduced the quantity and quality of song, a condition-dependent, phenotypically plastic signal. Contrary to our expectation, tail elongation had no effect on singing activity and song complexity. However, tail-elongated males produced songs with longer terminal parts ('rattles'). Long rattles are associated with highly competitive social contexts and high circulating levels of testosterone, suggesting that tail-elongated males were more frequently involved in either male-male aggressive or inter-sexual interactions. Therefore, this study shows that males are not displaying multiple signals at the maximum possible level, implying that this system is open to unreliable communication. However, long-term trade-offs between signal expression and viability may prevent males from displaying both signals at higher rates.Communicated by: M. Webster  相似文献   
228.
Summary Urine odors from 4 species of blind subterranean mole rats belonging to theSpalax ehrenbergi superspecies in Israel were evaluated to determine whether there were discriminable differences in the odors that were specific to different individuals, populations, and species of mole rats. Trained laboratory rats assessed these differences in an automated olfactometer using an operant conditioning paradigm. They demonstrated the discriminability of the urine odors in the 3 categories by their correct responses in generalization trials. These characteristic species, population and individual odors may provide these solitary, territorial and blind rodents a means for diverse chemical communication in spacing behavior, reproduction, species isolation and speciation.  相似文献   
229.
The structure of dominance relationships among individuals in a population is known to influence their fitness, access to resources, risk of predation, and even energy budgets. Recent advances in global positioning system radio telemetry provide data to evaluate the influence of social relationships on population spatial structure and ranging tactics. Using current models of socio-ecology as a framework, we explore the spatial behaviors relating to the maintenance of transitive (i.e., linear) dominance hierarchies between elephant social groups despite the infrequent occurrence of contests over resources and lack of territorial behavior. Data collected from seven families of different rank demonstrate that dominant groups disproportionately use preferred habitats, limit their exposure to predation/conflict with humans by avoiding unprotected areas, and expend less energy than subordinate groups during the dry season. Hence, our data provide strong evidence of rank derived spatial partitioning in this migratory species. These behaviors, however, were not found during the wet season, indicating that spatial segregation of elephants is related to resource availability. Our results indicate the importance of protecting preexisting social mechanisms for mitigating the ecological impacts of high density in this species. This analysis provides an exemplar of how behavioral research in a socio-ecological framework can serve to identify factors salient to the persistence and management of at risk species or populations. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.  相似文献   
230.
Many animal signals are performed in a highly redundant manner as in some bird species where males sing several renditions of one song type before switching to another. However, differences in signal redundancy between contexts and between individuals are only poorly understood. We found that chaffinches (Fringilla coelebs) in noisier areas (i.e., close to waterfalls and torrents) sang longer bouts of the same song type before switching to a new type, suggesting that they use increased serial redundancy to get the message across in noisy conditions. This is the first evidence of a noise-dependent adjustment of signal redundancy in a songbird. In addition, we found that song types with faster trills were sung in shorter bouts suggesting that the performance of highly redundant song series is probably limited by motor constraints. Thus, in noisy environments, serial redundancy in bird song may reflect a trade-off between successful signal transmission and preventing motor fatigue.  相似文献   
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