Predicting Long‐Term Changes in Riparian Bird Communities in Floodplain Landscapes

As anthropogenic impacts on riverine ecosystems expand, both aquatic and terrestrial ecosystems are influenced over large spatiotemporal scales. We predicted how riparian bird communities changed in response to long‐term changes in floodplain landscapes such as woodland expansion (i.e. rapid increases in vegetation cover on gravel bars and the progress of vegetation succession due to a decrease in the frequency and magnitude of flood disturbance). To test the hypothesis that woodland expansion after dam construction reduces the abundance of gravel bar‐nesting birds and increases the abundance of forest‐nesting birds, we estimated historical changes between past and present bird abundances using species distribution models across multiple rivers that were either unregulated or regulated by dams. We created past and present vegetation maps from remote sensing images and used habitat quantities as explanatory variables in the species distribution models. As we hypothesized, the estimated abundance of gravel bar‐nesting birds decreased and that of forest‐nesting birds increased because of woodland expansion in some regulated rivers. This suggests that anthropogenic alterations of riverine conditions (e.g. dam construction) can affect terrestrial ecosystems (e.g. riparian bird communities) through changes in floodplains (e.g. woodland expansion). In addition, our findings highlight the efficacy of combining spatial and temporal analyses when examining long‐term ecological dynamics. Copyright © 2013 John Wiley & Sons, Ltd.     

滨海湿地原生灌草群落土壤养分与盐分关系

通过灌草群丛划分、土壤采样以及室内测定、数理统计等方法,分析了黄河三角洲原生湿地灌草群落土壤的养分、盐分分布特征及相互关系,发现原生灌草群落土壤可溶性盐的垂直分布变异性较大,其中,碱蓬群丛与柽柳群丛土壤可溶性盐分布具有较强的表聚性,而土壤有机质含量表现为芦苇群丛>柽柳群丛>碱蓬群丛,且灌草群落中土壤C/N值都大于5,表明其有机质腐殖化程度较高。另一方面,土壤全氮与有机质存在明显的线性正相关;而土壤全盐与有机质、全氮之间存在明显的倒数关系,表明全盐对二者的制约作用,其中15~20g/kg的土壤盐分范围对应的是土壤全氮、有机质由迅速减少向缓慢减少的变化趋势。研究结果可以为盐碱土改良提供重要参考。     

The lesbian,gay, bisexual and transgender community online: discussions of bullying and self-disclosure in YouTube videos

Computer-mediated communication has become a popular platform for identity construction and experimentation as well as social interaction for those who identify as lesbian, gay, bisexual or transgender (LGBT). The creation of user-generated videos has allowed content creators to share experiences on LGBT topics. With bullying becoming more common amongst LGBT youth, it is important to obtain a greater understanding of this phenomenon. In our study, we report on the analysis of 151 YouTube videos which were identified as having LGBT- and bullying-related content. The analysis reveals how content creators openly disclose personal information about themselves and their experiences in a non-anonymous rhetoric with an unknown public. These disclosures could indicate a desire to seek friendship, support and provide empathy.     

Spatial variability of thermal regimes and other environmental determinants of stream fish communities in the Great Lakes Basin,Ontario, Canada

Temperature is one of the most important environmental variables in stream ecosystems because it affects the growth, survival and distribution of stream biota. This study examined if the spatial variability of thermal regimes and 18 other environmental variables were associated with fish communities in watersheds throughout the Great Lakes Basin (GLB), Ontario. The thermal regimes were defined as regimes 1, 2 and 3 and had maximum water temperatures of 26.4, 28.4 and 23.5°C, and spring warming rates of 0.20, 0.12 and 0.10 °C d^?1, respectively. The spatial variability of the thermal regimes (VTR) within the watersheds was summarized into four VTR groups: S1, S2, M23 and M123. Stream sites in S1 watersheds had temperatures characteristic of regime 1 whereas stream sites in S2 watersheds followed regime 2. M23 watersheds had sites with a mix of regimes 2 and 3 whereas M123 watersheds had all three thermal regimes at sites throughout watersheds. Canonical correspondence analysis (CCA) indicated that 16% of the variation in fish communities was related to the spatial VTR in the watersheds. Forward selection CCA indicated that elevation, the S1 VTR group, sparse forest cover, wetland area, base flow index (groundwater discharge potential), flow and industrial stress explained 42% of the variance in the fish communities. Simplified indicator species analysis (ISA) showed that different species could be used as indicators for each of the VTR groups. Human activities such as industrial development, deforestation, groundwater withdrawal and flow alteration all may affect the environmental variables related to stream fish communities. Copyright © 2010 John Wiley & Sons, Ltd.     

采用双层协调机制的服务社区模型

Web服务的动态组合技术作为有效实现服务增值功能的重要方法已成为业界研究和发展的焦点,纵观已有的研究成果,其协调机制可分为集中和分散两种.但实际应用中,这两种机制都存在不足.针对这一问题,提出了一种采用双层协调机制的服务社区模型,并讨论了该模型的体系结构、注册原理、发现算法、替换规则等问题,最后与传统模型进行对比分析.结果表明,这种采用传统集中和分散相结合协调机制的模型,将UDDl分层设计与管理,可以更好地支持存储和管理资源;社区的内部自治性有利于提高服务发现和替换的效率,从而更有效地支持Web服务的动态组合过程.     

面向联合检修的电力信息物理系统输电线路脆弱相关性辨识

为减少用户停电时间,电力企业常采取“一停多用,联合检修”模式。然而,检修计划往往侧重于关注线路本身的运行状态,而缺乏对电网整体运行性能的考虑。在跨区联合检修中,由于多条线路陆续停电检修,系统的脆弱性可能被放大。电力信息物理系统之间的融合关系也可能加剧故障跨域传播的深度和广度。在协同破坏效应下,系统存在连锁故障及大停电的可能。为此,提出一种该场景下输电线路脆弱相关性的辨识方法。首先,对联合检修中的能量流动和信息传输过程建模,构建联合检修事故记录数据库。其次,挖掘数据库中存在脆弱相关性的线路组合,通过计算线路组合在诱发停电事故时的贡献度,实现脆弱相关性的量化。仿真结果表明：联合检修时,脆弱相关的线路组在物理层和信息层都表现出了协同破坏效应。所提方法能有效地辨识和量化线路组的脆弱相关性,为制定更加合理的联合检修计划、避免大停电事故的发生提供理论指导。     

On the linguistic nature of cyberspace and virtual communities

This paper argues for a linguistic explanation of the nature of Virtual Communities. Virtual Communities develop and grow in electronic space. or cyberspace. Authors such as Benedikt Meyrowitz and Mitchell have theorised about the nature of electronic space whilst Lefebvre. Popper, Hakim Bey (aka Lamborn Wilson) and Kuhn have theorised more generally about the nature of space. Extending this tradition and the works of these authors, this paper presents a language based perspective on the nature of electronic spaces. Behaviour in cyberspace is based on and regulated by hardware, software tools and interfaces. A definition of electronic space cannot be given beyond its linguistic characteristics, which underlie and sustain it. The author believes that the more users and developers understand the relationship between language and cyberspace, the more they will be able to use specific metaphors for dwelling and inhabiting it. In particular, MUDs/MOOs and the Web are interesting places for testing and observing social behaviours and dynamics.     

A web-based self-testing system with some features of Web 2.0: Design and primary implementation

Self-testing is a means to check learning effect. Besides time–space restriction, there are many deficiencies in traditional offline self-testing. With the development of information technology, learners can have self-testing on the Internet. Self-testing on Internet, namely, web-based self-testing, overcomes time–space limitation of traditional offline self-testing, but there are still several disadvantages such as monotony and lack of interaction. In the article, a web-based self-testing system with some features of Web 2.0 is designed and implemented, aiming at overcoming the weaknesses of current online self-testing system. Firstly, taking English self-testing as an example, the framework of the system and functions of its main modules is designed according to theories of social learning and constructivism as well as the idea of Web 2.0 and the characteristics of server-side programming. Secondly, in accordance with the design above, a new system is implemented for English learners primarily by using HTML, JavaScript, PHP, and MySQL comprehensively. The role and duty of webmaster are also described briefly. To test the system, some English learners were invited randomly to use it, and feedback information was collected from them after a period of time. It is shown by feedbacks that most learners are satisfied with the system, and the system is of distinct features and favorable practicality compared with other systems, but it still needs to be improved in the design of user interface and some other details. Results in the article demonstrate that the new system can overcome the shortcomings of current systems to some extent.