Can human disturbance promote nestedness? Songbirds and noise in urban parks as a case study

Several explanations have been proposed to understand the existence of nested subset patterns in biological communities, including selective extinction, differential colonization, nested species-habitat relationships, random placement from a common species pool, and human disturbance. We study if songbird assemblages inhabiting urban parks in the Puebla-Cholula Metropolitan Area (Mexico, an urbanizing country) exhibit a nested subset pattern, and apply information-theoretic (IT) methods to rank the likelihood of the abovementioned processes as competing hypotheses explaining nestedness. A total of 21 study sites were considered, where 38 Passeriformes species were retained for nestedness analyses (13 species with preferences for forest habitats, and 25 for non-forest habitats). Neither the number of species per site nor the number of sites per species followed expectations from the random placement hypothesis. In addition, using the NODF index for measuring nestedness and different null models for generating random matrices, we found that songbird assemblages inhabiting urban parks were significantly more nested than expected. The IT approaches we followed evidenced that the two most important ecological processes promoting nestedness were selective extinction and human disturbance: site richness orderly increased according to area, and decreased according to background noise levels. Results are discussed taking into account habitat-related sound degradation and transmission properties, and differential susceptibility to anthropogenic noise among songbirds with preferences for forest versus non-forest habitats. To the best of our knowledge, this is the first time that noise pollution, a pervasive kind of human disturbance in modern cities, is acknowledged as a factor promoting nestedness in bird communities.     

土工格栅嵌锁力的理论计算方法探讨

针对土工格栅嵌锁力提出了一套简化的理论计算方法。通过对碎石填料和格栅作用模型的简化处理,给出了一种格栅与填料颗粒的单元嵌锁模式,并通过对该嵌锁模式下的填料颗粒的两种运动趋势—平移和转动进行讨论和分析,推导了不同条件下格栅的极限拉力,得出了最终的单元嵌锁力。     

Comparative study of the physico-chemical parameters of the coastal waters in rivers Matla and Saptamukhi: Impacts of coastal water coastal pollution

A qualitative and quantitative research has been performed on the physico-chemical parameters of the neighboring coastal waters of the rivers Matla and Saptamukhi in the Sunderban district, West Bengal. The distribution pattern of eight physico-chemical parameters, namely pH, salinity, dissolved oxygen, suspended solids, nitrogen and phosphorus concentrations (inorganic and total) has been graphed and compared for the two rivers over a time period of ten years (??90s decade). A statistical analysis has been carried out and the correlation data between these parameters has been rationalized based on both natural and man-made activities during that time. This has pointed to various causes behind coastal pollution of river waters. The changes in water quality have been related to flood impacts, storm surge, eutrophication, domestic sewage, agricultural and industrial wastes. In order to avoid coastal degradation and maintain environmental balance, it is very important to understand the impact of these parameters on coastal zones.     

油气处理终端山体滑坡风险评估及治理措施研究

某陆上油气终端处理厂作为海洋石油开采过程中的重要组成部分,计划在温州洞头县新建,终端场地为原采石场开挖后所形成,由于人工开挖,终端场地一侧为梯形开挖山体,山体表面情况复杂,滑坡风险大,通过采用边坡稳定性分析工具对山体滑坡风险进行分析,并结合滑坡灾害破坏机理对滑坡后的破坏范围和程度进行了分析研究,在此基础上提出了相应的治理措施和建议。风险评估技术路线可以应用于类似工程施工山体滑坡风险评估和治理项目中,进而有效控制山体滑坡风险。     

我国城市基础设施建设资金运作模式研究

首先回顾了我国城建资金相关政策的历史演变,以及我国城建资金总量及构成的变动情况;然后从城建资金来源、支出和相关运作单位和部门三方面总结了我国城建资金整体运作模式,重点分析了政府部门主导型、城投公司主导型以及BOT等公私合作型运作模式的特点,并进一步分析了乡镇、县和地级市三个不同行政级别城建资金运作模式的特点。最后,总结了我国城建资金运作模式的特点及现状问题,并对城市规划中如何引入并强化城建资金研究及实践提出了建议。     

基于转角位移法对正交各向异性桥面板内力的分析计算

由于大量的焊接连接件、高度集中荷载作用和它们导致的大量应力循环,正交各向异性桥面板对疲劳破坏非常敏感。在公路桥中,焊接在桥面板的加劲腹板通常易于遭受疲劳破坏。开发了一个分析模型,可以运用转角-位移法计算应力。它构建了一个桥面板的横截面模型,但是其中考虑了整个正交板的水平和竖向刚度以及纵向加劲肋的扭转刚度。这种方法可以计算桥面板横截面上的所有内力。     

大跨径混凝土拱桥拱上立柱接头施工质量控制

阐述了广西柳州市三江县中山大桥拱上立柱预制与现浇接头施工,介绍了接头模式、预制及现浇立柱端头处理、接头对接、接头混凝土施工控制要点,结合实际提出了对缺陷处理的措施,从而为实际工程施工积累经验。     

Study on Urban Infrastructure Development Financing in China(Ⅱ)

4.Typical modes of infrastructure financing in China After summarizing the general situations of infrastructure financing in China,further analyses will be made on several typical modes of infrastructure financing on the basis of the interviews,surveys,and data collections in certain Chinese cities.     

Trace elements in home-produced eggs in Belgium: Levels and spatiotemporal distribution

The purpose of this study was to evaluate the levels of arsenic, cadmium, lead, copper and zinc in home-produced eggs, soils and kitchen waste samples of private chicken owners in Belgium, and to determine spatiotemporal differences in trace element contents in eggs. Eggs were sampled in all provinces of Belgium in autumn 2006 and spring 2007. A total number of 59 private chicken owners participated in the study. Trace elements were determined by inductively coupled plasma-mass spectrometry except for mercury, which was determined by atomic absorption of mercury vapour. The mean fresh weight concentrations in eggs in autumn and spring respectively were < 8.0 and < 8.0 µg/kg for arsenic, 0.5 and < 0.5 µg/kg for cadmium, 116 and 74 µg/kg for lead, 0.43 and 0.52 mg/kg for copper, 20.3 and 19.2 mg/kg for zinc, and 3.15 and 4.44 µg/kg for mercury. Analysis of variance determined significant differences in some trace element concentrations in eggs among seasons and regions in Belgium. Average concentrations of arsenic, cadmium and mercury corresponded well with values measured in other countries, while copper and zinc concentrations were within the same order of magnitude as in other countries. Average lead concentrations were high compared to concentrations in eggs from other countries and correlated well with lead concentrations in soil, indicating that the soil is an important source. Other sources of trace elements in eggs might be home-grown vegetables and forage (grass and herbs), and indirectly, air pollution.     

Influence of microbiological activity in granular activated carbon filters on the removal of organic compounds

In order to show the influence of bacterial activity in GAC filters on the removal of organic matter, experiments were carried out with diluted aqueous solutions of biodegradable and of non-biodegradable compounds under sterile and non sterile conditions. Productions of CO₂ show clearly that the bacterial activity can lead to a complete elimination of the biodegradable solute and to a partial microbiological regeneration of the adsorbent. By its influence on the competitive adsorption, the biological removal of biodegradable compounds leads to an increase of GAC adsorptive capacities for the non-biodegradable organic matter.