Does female plumage coloration signal parental quality? A male removal experiment with the bluethroat (Luscinia s. svecica)

Females in several sexually dimorphic species with conventional sex roles possess ornamental traits that resemble those found in males. The evolution of such traits, however, is still poorly understood. Bluethroats (Luscinia s. svecica) are socially monogamous, sexually dichromatic passerine birds, in which female throat patch coloration varies from near absence to near full expression of male-like coloration. A recent study, demonstrating that male bluethroats prefer colourful females, suggests that female coloration is subject to sexual selection through male choice. However, the benefits males may gain from mating with colourful females have not yet been identified. In this study we tested the hypothesis that female coloration signals parental quality (the good-parent hypothesis). During the course of the same day, we recorded female care both in the presence and the absence of the male mate. The latter was done to eliminate the confounding effect of variable male care by removing the male temporarily. Female coloration did not correlate with female feeding rates either in the presence or in the absence of the male. Female feeding rates in the absence and the presence of the male were positively, although weakly, correlated. Female coloration did not correlate with female ability to compensate for the loss of male care, or with the change in brood mass during male removal. Therefore, there is no evidence for the good-parent hypothesis to explain female plumage coloration in bluethroats. Received: 4 March 1999 / Received in revised form: 14 October 1999 / Accepted: 23 October 1999     

Sexual dimorphism in house sparrow eggs

Recent evidence has revealed an apparently high degree of control by female birds over the physiological aspects of their reproduction and offspring sex allocation, consistent with adaptive hypotheses of sex allocation and differential investment in their offspring. In the house sparrow, we investigated possible mechanisms that may be used by females to enhance the fitness returns from a reproductive effort. Using molecular techniques, we demonstrate that house sparrow eggs containing male embryos are significantly larger than those containing female embryos. We also found that male embryos were laid randomly with respect to laying order. We speculate that this sexual dimorphism of eggs is adaptive, because male house sparrows show greater variance in condition-dependent reproductive success than females. More important, the result provides further evidence of the ability of females to detect or control ovulation of either male or female ova and to differentially invest in one sex over the other. Received: 19 January 2000 / Revised: 29 June 2000 / Accepted 20 July 2000     

北京市第三产业用水特征及其发展策略

第三产业在北京市的产业格局中占有日益重要的地位,从水资源配置的视角探寻三产结构优化策略具有重要现实意义。采用LMDI分解方法,定量分析北京市第三产业用水结构变化驱动力特征,基于投入产出法计算各行业部门的用水系数,并进行用水特性和行业关联的聚类分析。结果表明,产业规模的快速增长是第三产业用水需求增长的决定性因素,2007-2013年间,累计使总用水量增加了34 476.24万m~3,产业结构效应和技术效应则对用水量的增加起抑制作用,两者分别使用水量减少2 861.29万m~3和21 908.17万m~3,产业结构效应和技术效应对用水的抑制作用不及经济产出效应对用水的拉动作用,最终导致用水量的增长。不同行业之间的用水系数有较大差异,水利、环境和公共设施管理、教育等行业的用水系数相对较大,批发和零售业、金融业的用水系数相对较小,科学研究技术服务和地质勘查等行业的用水乘数较大。第三产业中的高用水行业包括住宿和餐饮业等7个行业部门,潜在高用水行业包括批发和零售业等6个行业;一般用水行业为居民服务和其他服务业。聚类分析结果表明,对于诸如租赁和商务服务业及科学研究技术服务业等感应度系数较大的行业,应优先保障水资源的供给,使用高配额、低水价的管理方式;对于文化体育业等感应度系数较小的行业,可使用低配额、高水价的管理方式,限制用水量;对于配额高且水耗低的产业,可采取水权转让手段,将富余的水权转让给水耗高且产出高的产业。最后,针对研究结果,提出水权交易、技术推广、政策管理与机制构建四方面建议,为第三产业经济增长与用水之间的协调发展提供借鉴。     

Polybrominated diphenyl ethers occurrence in major inflowing rivers of Lake Chaohu (China): Characteristics,potential sources and inputs to lake

Eight commonly occurring polybrominated diphenyl ethers (PBDEs), including BDE 28, 47, 99, 100, 153, 154, 183, 207, and 209, were investigated in water samples from seven major inflowing rivers of Lake Chaohu to determine the distribution characteristics, potential sources and inputs to the lake. The sum of 8 BDE congeners (Σ₈PBDEs) had a concentration varied from 0.31 to 84 ng L⁻¹, with those of BDE 209, BDE 47, BDE 99, and BDE 153 being 0.31–83, <0.012–0.36, <0.012–1.3, and <0.012–0.77 ng L⁻¹, respectively. These levels were in the high range of the global PBDEs concentrations in the water environments. The highest concentrations of Σ₈PBDEs were detected in the western rivers, of which the main pollution sources were strongly related to human activities in urban centers, such as automobile-derived wastes. A sewage treatment plant was likely an important source of the lower brominated BDEs input to one western river. The correlation analyses (all p < 0.05) between PBDEs and DOC, TN, TP, and EC, suggested that the distributions and sources of PBDEs in rivers might also be related with the soil erosion by heave floods. Σ₈PBDEs input to Lake Chaohu from the rivers outlets was estimated at 344 kg yr⁻¹ during the flood season. BDE 209 was the dominant contributor with an input of 340 kg yr⁻¹, followed by BDE 99 (1.3 kg yr⁻¹), BDE 47 (0.83 kg yr⁻¹) and BDE 153 (0.60 kg yr⁻¹).     

以应对自然灾害为核心的应急资源投入保障机制研究

应急资源是应急管理工作的重要支撑力量,其保障能力的形成是通过应急资源投入保障机制实现的。针对以应对自然灾害为核心的应急资源投入保障机制,以应急资源投入保障机制的五大主体(中央政府、地方政府、中央部门、地方部门、社会力量)为研究枢纽,系统地梳理了我国应急资源投入保障机制的现状;结合重大案例,以保障过程的三个环节(资金筹集、资金使用和保障能力形成、监督协调)为研究线索分析当前我国应急资源投入保障机制存在的问题,并寻找出其核心症结,即缺少专门的应急资金体系支持应急管理工作和没有统一的应急管理机构;针对核心症结,进行思考并提出相应的政策建议:设立应急管理专用资金体系和建立一体化的应急管理机构。     

Spatial distribution of dissolved Pb, Hg, Cd, Cu and As in the Bohai Sea

Characteristics of the spatial distribution of selected dissolved heavy metals were analyzed during large scale surveys from August 12 to 25,2003 in the Bohai Sea.Dissolved Pb was the only element with average concentrations higher than the grade-one sea water quality standard of China.The spatial distribution of dissolved Pb in surface water was similar to those of Cd,Cu and As,where the isopleths generally indicated decreasing values from the bays to the central areas.Only for Hg did the high concentrations not only appear in Liaodong Bay,Bohai Bay and Laizhou Bay,but also in the Central Area,viz.not only in inshore but also in offshore areas. Vertical distributions of dissolved Pb,Cd,Cu and As were largely uniform,while that of dissolved Hg increased with depth.We infer that the input of pollutants from land was the main influencing factor for the detected distribution patterns of dissolved heavy metals, followed by the dynamics of sea water,release from bottom sediments and biochemical processes.Comparing with historical data, average concentrations of dissolved heavy metals appear to decline in recent years.     

Environmentally Sensitive Productivity Analysis of the Canadian Pulp and Paper Industry, 1959-1994: An Input Distance Function Approach

This study employs a parametric input distance function that incorporates both desirable and undesirable outputs to provide a more complete representation of the production technology from which environmentally sensitive productivity and efficiency measures can be generated. This framework also generates pollution abatement cost estimates that are useful for policy making. An input-based Malmquist index of productivity growth that appropriately credits the producer not only for increases in marketable or desirable outputs but also for the production of improved environmental quality through pollution abatement activities is derived from the input distance function. The method was applied to time series data from the Canadian pulp and paper industry. Our shadow price estimates indicate that the marginal cost to producers of pollution control has been rising. The main conclusion of this study is that productivity improvement, from the social viewpoint, has been stronger than conventional measures would suggest.     

Home range overlap of mothers and their offspring in the sleepy lizard, Tiliqua rugosa

This paper reports a field investigation of interactions between juveniles and their mothers in the Australian sleepy lizard, Tiliqua rugosa. In their first spring season, juvenile lizards maintain home ranges largely within the home range of their mother. Juvenile home ranges are significantly smaller than those of adult males and females, and juveniles move significantly less often and significantly shorter distances than adults. While siblings were never found together in the spring, they showed a significant tendency to be closer to each other than if they were randomly located in their home ranges. Juveniles and mothers were never found together, nor was there any evidence for any positive (or negative) spatial association. Nevertheless, the extended tolerance of home range overlap represents a greater degree of mother-offspring association than has been previously reported for other lizards. Despite this, the level of parental care can only be described as minimal. Received: 20 June 1997 / Accepted after revision: 29 December 1997     

从语言输入输出理论谈互动式课堂教学

通过对语言输入与输出理论以及互动式教学法的分析,作者认为把前者融入到后者之中来进行英语教学可取得更好的效果,还强调既要重视语言输入,又要强调语言的输出。     

内蒙古温带草原羊草叶片功能特性与光合特征对外源氮输入的响应

以内蒙古锡林河流域羊草草原典型植被羊草(Leymus chinensis)为研究对象,探讨了4个不同氮素输入水平(0、5、10和20g·m-·2a-1)下羊草叶片功能特性与光合特征的响应,并分析了外源氮输入背景下草地生态系统固碳潜势的变化.结果表明:中等水平施氮(10g·m-·2a-1)显著增加了羊草叶面积、叶绿素相对含量、叶氮浓度与净光合速率,但与中氮相比,高氮(20g·m-·2a-1)输入下却有所下降;施氮不仅对叶片净光合速率有一定程度的促进作用,而且延长了光合作用高峰期的持续时间;随着氮素添加梯度的增加,羊草叶片蒸腾速率降低,瞬时水分利用效率增高,气孔导度增大,胞间CO2浓度逐渐减小.从光合固碳的角度来看,适量的外源氮素输入有利于草地生态系统固定更多的CO2.