Biofilm Responses to Flow Regulation by Dams in Mediterranean Rivers

Dams regulate downstream hydrology and modify water quality, which in turn can impinge on the biota, especially in rivers naturally subject to large hydrological variability, such as those under Mediterranean climate. The effect of dams on biofilms was analysed in three tributaries (Cinca, Siurana and Montsant) of the Ebro River (NE Spain). We hypothesized that flow regulation would lead to lower spatial variability of biofilms on the streambed and to a decrease in their metabolic rate per unit biomass, especially during low flow periods. Biofilm characteristics were studied in five transects evenly spaced along river reaches upstream (control) and downstream (impact) of dams in each river, along with riverbed granulometry, hydraulics and water chemistry. Chlorophyll‐a, respiratory activity, photosynthetic capacity and efficiency, and extracellular enzymatic activities (β‐d ‐glucosidase, alkaline phosphatase and leucine‐amino‐peptidase) of epilithic biofilms were measured in different seasons. Spatial variability of chemical and biological variables was reduced downstream of the dams. Chlorophyll‐a concentration, photosynthetic efficiency and respiration capacity were higher in impact than in control reaches, but generally, low inorganic phosphorus concentrations resulted in comparable phosphatase activities downstream and upstream of dams. On the other hand, β‐d ‐glucosidase and leucine‐amino‐peptidase activities were higher at impact reaches. Biofilms were thicker and metabolically more active at the impact reaches, with higher ability to transform dissolved organic matter. Overall, results from this study provide evidence that dams can largely affect the structure and activity of river biofilms, with foreseeable important consequences for river ecosystem functioning. Copyright © 2014 John Wiley & Sons, Ltd.     

河南省水生态文明建设试点城市生态系统健康评价

在总结城市生态系统的属性并分析其健康内涵的基础上, 通过频度统计法, 建立评价指标体系。采用海明贴 近度, 建立模糊物元模型, 对河南省第一批水生态文明城市建设试点郑州、 洛阳、 许昌 2000 年- 2013 年间城市生态 系统的健康水平进行评价, 分析影响城市生态系统健康发展的各要素, 结果表明: 郑州、 洛阳和许昌整体的城市生态 系统健康水平呈上升趋势, 但健康改善程度并不显著, 且部分指标有恶化趋势; 相同时期内, 城市生态系统的健康水 平排序由高到低依次为郑州、 洛阳、 许昌, 但其增长速率则为许昌最快、 郑州最慢; 各城市不同要素之间的健康程度 差别较大, 且不同城市各要素之间的协调性较低。因此, 未来应针对健康程度较差的要素重点发展, 提高各要素之 间的协调性, 进一步提高城市生态系统整体的健康水平。     

普适计算环境下基于情境的提醒服务自协调策略研究

由于老年人生理机能减退,针对老年人的提醒服务应用十分广泛.该类服务应考虑到老人的活动特征和环境特征才能提高服务效果,减少不必要的干扰.情境感知技术的发展为提醒服务的改进提供了契机,将情境引入到提醒服务的设计中,采用OWL本体方法构建领域内情境与服务知识的语义模型,以提醒服务平台的方式集成领域内提醒相关的设备与服务,并结合本体模型采用SWRL规则设计提醒服务的自协调策略,从而提高平台上不同提醒服务的自适应能力.通过模拟若干情境,采用Protégé和Pellet推理机验证了本体模型的正确性和协调规则的有效性.     

一种新的数字图书馆云服务用户满意度模型

随着云计算技术的发展,数字图书馆云服务评价成为迫切需要解决的问题.基于层次分析法(AHP),设计一种新的用户满意度模型评估数字图书馆云服务;为了从评估者角度获得测评指标的相对重要程度,提出一种新的AHP算法判断矩阵构造方式.实例表明:1)用户满意度模型能准确定位评估人员迫切需要改进的数字图书馆云服务; 2)改进的AHP算法能够从评估人员角度获得测评指标的权重值,有助于提高用户满意度的准确性.     

碟形湖在鄱阳湖湿地生态系统的作用和意义

"碟形湖"是指鄱阳湖湖盆区内枯水季节显露于洲滩之中的季节性子湖泊,具有特殊的地貌特征和水文特性、复杂多变的湿地景观和丰富的生物多样性等特征.在碟形湖及其周边,湿生与水生植物群落有序分布、季节性演替;静水水域有利于底栖动物和鱼类生长育肥;缓慢下降的水位、逐渐伸展的泥滩为越冬候鸟持续提供丰富的食物和歇息环境,全湖80%以上的水鸟在碟形湖区域越冬.高低不一、分布广泛的碟形湖群有效地缓解了干旱、洪水灾害对鄱阳湖湿地生态系统的冲击,对于维护全球生态系统的完整性和生物多样性具有重要作用.最后提出了加强碟形湖保护和管理的对策.     

超级计算中心客户细分及差异化服务策略研究

本文以中国科学院计算机网络信息中心超级计算中心（以下简称超级计算中心）客户服务工作为研究对象,运用 K-means 算法对客户进行细分,进而对每类客户群提出相应的差异化服务策略。实施差异化服务策略可以更好地分配资源、提供更有效的客户服务。     

基于XML元素加密的Web服务安全策略

Web服务使开发人员能够建立一种面向服务的、平台无关的、分布式的应用程序架构,另一方面Web服务使用XML在网络中进行数据交换,如何提高Web服务的安全性则成为需要解决的关键问题。本文论述了基于对XML文件中的元素进行加密的策略,从而保证了Web服务安全性。     

Using the World Wide Web for Art and Humanities Reference Services

Abstract

This paper describes what the World Wide Web is and what is needed in order to access its information. It discusses the future of art and humanities reference resources and presents criteria for evaluating Web sites. A review of the literature related to “Generation X” and their information expectations was done. There is an annotated list of specific World Wide Web resources related to African Diaspora, American Poetry, Comparative Literature, Gay and Lesbian Literature, and Outsider Art. This list provides examples for evaluation and is not meant to be exhaustive.