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41.
This investigation conducted a full-scale survey the drinking water distribution system in Kaohsiung city, Taiwan. The aim was to investigate whether the distribution system was capable of maintaining high water quality from the water treatment facilities through to the end user. The results showed that the distribution system can maintain high water quality, except for suitable chlorine residuals. The authors plotted chlorine residual contour maps to identify areas with low chlorine residuals, helping them prioritize sections that must be flushed or renewal. The contour maps also provide sufficient and clear information for locating booster chlorination stations. Contour maps enable water facilities to identify how water quality decays in the distribution systems and the locations of such decay. Water quality decay can be caused by properties of pipeline materials, hydraulic conditions, and/or biofilm thickness. However, understanding the exact reasons is unnecessary because the contour maps provide sufficient information for trouble-shooting the distribution systems.  相似文献   
42.
DNA fingerprinting was combined with field observations over four breeding seasons to investigate the social structure and mating system of the laughing kookaburra (Dacelo novaeguineae). Groups comprised a socially dominant pair and up to six helpers of either sex. Helpers were always recruited from young hatched in the group. Territorial inheritance, which is a feature of other cooperative breeders and an oft-cited benefit of philopatry, did not occur. Helpers only attained dominant status in an established group by dispersing into a vacant dominant position in that group. However, helpers could also form new groups by excising a new territory, often through a ”budding” process. The mating system was overwhelmingly monogamous. There were no cases of extra-group parentage in a sample of 140 nestlings; within groups of three or more birds, dominance predicted parentage almost perfectly (99.2% of 129 nestlings), irrespective of whether helpers in the group were related to one or both dominant birds. This is contrary to predictions from models of reproductive skew, possibly because they currently fail to incorporate the willingness of females to share reproduction among males. Received: 15 May 1999 / Received in revised form: 2 November 1999 / Accepted: 6 November 1999  相似文献   
43.
In the meerkat (Suricata suricatta), a cooperative mongoose, pups follow potential feeders while the group is foraging and emit incessant calls when soliciting food from them. In contrast to a ’stationary’ brood of chicks, in which nestlings are fed at a fixed location, meerkat pups are ’mobile’ and become spread out. The question arises whether meerkat pups that experience different constraints to those facing chicks have evolved similar begging strategies. This paper describes the vocalisations that meerkat pups emit in the context of begging and investigates the influence of these calls on food allocation by older group members and on the behaviour of littermates. Meerkat pups use two types of calls when soliciting food from a potential feeder. The most common is a ’repeat’ call, which pups emit continuously when following an older forager over several hours a day. In addition, when a potential feeder finds a prey item, the pups next to it emit a bout of calls with increased calling rate, amplitude and fundamental frequency, termed ’high-pitched’ calls. Observations, together with playback experiments, showed that more prey was allocated to pups that called longer and more intensely. The pup closest to a feeder was almost always fed. The probability of emitting high-pitched calls did not depend on the time since a pup had received food, and the change from repeat to high-pitched calls occurred suddenly. The main function of the high-pitched call, therefore, does not appear to be to signal a pup’s hunger state. More likely, the two calls, in the context of begging, may be an adaptation to energetic constraints in a mobile feeding system. Pups, which are dispersed during foraging, may emit repeat calls over long periods to prevent potential feeders from eating all the prey themselves. At the moment a potential feeder finds prey, pups may give the more intense high-pitched calls to direct feeders to bring the food item to them and not to a littermate. Therefore, unlike the stationary feeding system where chicks emit one type of begging call when the feeder approaches the nest, meerkats, with a mobile feeding system, have evolved two discrete types of vocalisations in the context of begging. Received: 22 November 1999 / Revised: 1 July 2000 / Accepted: 17 July 2000  相似文献   
44.
One of the most interesting aspects of the mating system of pied flycatchers is the regular occurrence of polygyny. Here we present data on the reproductive success of polygynously paired pied flycatcher males compared to monogamous males based on paternity analyses through DNA fingerprinting. Males paired with two females suffered a higher loss in reproductive output per female compared to monogamous males due to (1) a greater proportion of unhatched eggs in their broods, (2) greater nestling mortality and (3) a greater probability of being cuckolded. Nevertheless, the number of fledglings was significantly greater for polygynous males. Based on the number of nestlings that returned for subsequent breeding seasons, however, the reproductive success of monogamous and polygynous males did not differ significantly. These data raise the question as to why males attempt polygyny. Received: 16 August 1999 / Received in revised form: 15 March 2000 / Accepted: 18 March 2000  相似文献   
45.
在长期定位监测的基础上,研究了耕作改制对土壤肥力的影响,结果表明,耕作改制后,肥料投入明显增加,养分平衡朝着有利于提高肥力的方向发展;因土、因作物进行配方施肥,并实行秸秆还田,则改制后土壤肥力能得到提高;合理耕作轮作,有利于解决地力矛盾和季节矛盾,实现高产、稳产、低成本。  相似文献   
46.
美国海军舰艇命名体系由任命前缀、舰艇名称、分类代号、舷号4类要素构成,首先分析了每类要素对于命名体系的贡献,然后基于美国海军舰艇命名体系,以美国海军舰艇名册为数据源,通过要素提取、规则建立等步骤分析美国海军现役舰艇组成。经过分析,美国现役715艘舰艇分为战斗舰、辅助舰、战斗艇、支援艇、未在分类代号中定义等5大类67类型177级别,通过对比基于类型与级别规则、基于任命前缀规则的结果挖掘出美国海军现役舰艇组成规律。  相似文献   
47.
Comprehensive temperature monitoring was done in an in-vessel forced-aeration static-bed composting process using sewage sludge. The three layers that divided the compost pile horizontally showed different temperature distributions. The temperature of the top layer appeared not to be influenced by the ambient temperature. The temperature of the center area of the top layer was taken to be the representative temperature for evaluating composting start-up performance. The temperature of the bottom layer was strongly influenced by the ambient temperature, and the temperature of the center area of the bottom layer was taken to be the representative temperature for pathogen control as it was the minimum temperature in the reactor. Composting start-up performance was influenced by several factors when the ambient temperature was either below or above 20°C. When the ambient temperature was below 20°C, the time taken to reach 65°C (T 65) was influenced by the temperature of inflowing air, but when the temperature was higher than 20°C, it was influenced by the ratio of sewage sludge to seed compost (F/S). T 65 was least when F/S was 1–2. Received: January 9, 2001 / Accepted: October 10, 2001  相似文献   
48.
人工湿地污水处理系统脱氮研究进展   总被引:5,自引:1,他引:5  
系统地介绍了人工湿地去除污水中氮污染物的机理及国内外研究进展,详细阐述了影响人工湿地污水处理系统脱氮的内、外界因素,对于人工湿地污水处理工艺的推广应用提供科学依据。  相似文献   
49.
集体林地使用权市场制度的建立与完善   总被引:6,自引:0,他引:6  
集体林地使用权市场将是我国南方集体林区土地市场发展的主要内容,它的健康发展需要一套制度来保障.在介绍集体林地使用权市场类型的基础上,分析了我国集体林地使用权市场制度的建设状况,并提出了今后急待建立和完善的林地使用权市场制度的主要内容.  相似文献   
50.
随着经济的高速发展,环境污染事故也呈现出上升的势头,环境污染事故不仅造成了环境危害,而且对人民群众的安全产生了重大威胁。鉴于环境污染事故的多发性、危害性,应急处置显然非常重要,而构建强大的应急处置信息系统有助于应急处置和分析决策的顺利进行。本文分析了环境应急处置需求,提出了建立环境污染应急管理信息系统的设计框架。  相似文献   
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