R/S法的土石坝施工期沉降规律及预警标准研究

为提高施工期土石坝沉降安全性,研究其具有复杂非线性特征的施工期沉降规律和相应的预警标准。基于国内某在建高土石坝的沉降数据,采用R/S法分析坝体不同高程测点、同高程测点和同测点不同时期沉降数据的Hurst指数及分形维数,提出评价坝体施工期沉降安全性的预警标准。结果表明:各测点的Hurst指数最小值为0.763,坝内各处沉降仍处于快速增长阶段;坝体下部比上部、中部比下游堆石区沉降能更快趋于稳定,且坝体下部的沉降速率已经渐趋平缓。     

民营企业安全文化模型及其实证分析

针对民营企业特点,基于交互安全文化模型,建立民营企业安全文化模型并辨识 关键元素,以赛轮金宇股份有限公司为例进行实证分析。在广泛参考国内外相关研究的 基础上,设计调查问卷,运用粗糙集ROSETTA软件对测量结果进行属性简约,最终确定 15个安全文化元素;借助MATLAB,采用熵权法确定各元素权重,然后进行可拓综合评价 。评价结果表明该企业的“高层管理者重视”一项得分为4.82,水平较高,整体文化等 级属于“良”,级别特征变量j*=3.138 1。“创造安全舒适的工作环境”、“建立合理 的奖惩制度”、“定期进行应急演练”3个方面得分偏低,是安全文化建设需要重点加 强的方面。     

New mine capacity from yet-to-be found copper deposits

The copper industry in the USA is declining, but exploration for copper has been particularly promising in western Montana. The potential copper mine capacity of the area was estimated by using an interdisciplinary geological-economical assessment technique that categorizes deposits on the basis of development probability. Development probability is quantified and aggregated into potential new mine supply curves, which summarize resource potential of the region. The results suggest that copper resources in Montana and elsewhere are potentially large and that these resources probably will be mined at higher copper prices. This mineral assessment technique increases the usefulness of traditional methods for planners and policy makers.     

基于MODIS植被指数的浑善达克沙地植被物候变化

基于近20a MODIS的2种植被指数数据,利用Logistic曲线曲率极值法和动态阈值法,对浑善达克沙地植被物候进行了提取,分析其时空变化,并利用研究结果数据,分析植被物候对高程和气象因子的响应.结果表明,2000~2019年间研究区的植被物候呈微弱波动趋势,浑善达克沙地植被返青期（SOS）主要集中在110~140d,枯黄期（EOS）主要集中在250~280d,整体呈微弱推迟趋向（0.28d/a）,生长季长度（LOS）主要集中在120~170d,整体呈微弱延长趋向（0.23d/a）.在空间分布上,占研究区51.51%的区域植被SOS呈提前趋势;占研究区67.02%的区域植被EOS呈提前趋势,并且占研究区32.98%的区域植被EOS呈推迟趋势.占研究区62.71%的区域植被LOS呈延长趋势.在海拔900~1500m区间,随着海拔升高,SOS显著推迟,EOS不显著提前,LOS显著缩短.前一年11、12月和当年1、2、4月降水量对SOS有提前作用.6、7、8、9月份气温和降水都对EOS推迟有明显的作用.总的来说,浑善达克沙地植被物候与气候因子的相应规律比较复杂,表现出季节性的差别及地形的差异性.     

Variation in Assemblages of Small Fishes and Microcrustaceans After Inundation of Rarely Flooded Wetlands of the Lower Okavango Delta, Botswana

Water extraction from floodplain river systems may alter patterns of inundation of adjacent wetlands and lead to loss of aquatic biodiversity. Water reaching the Okavango Delta (Delta), Botswana, may decrease due to excessive water extraction and climate change. However, due to poor understanding of the link between inundation of wetlands and biological responses, it is difficult to assess the impacts of these future water developments on aquatic biota. Large floods from 2009 to 2011 inundated both rarely and frequently flooded wetlands in the Delta, creating an opportunity to examine the ecological significance of flooding of wetlands with widely differing hydrological characteristics. We studied the assemblages of small fishes and microcrustaceans, together with their trophic relationships, in temporary wetlands of the lower Delta. Densities of microcrustaceans in temporary wetlands were generally lower than previously recorded in these habitats. Microcrustacean density varied with wetland types and hydrological phase of inundation. High densities of microcrustaceans were recorded in the 2009 to 2010 flooding season after inundation of rarely flooded sites. Large numbers of small fishes were observed during this study. Community structure of small fishes differed significantly across the studied wetlands, with poeciliids predominant in frequently flooded wetlands and juvenile cichlids most abundant in rarely flooded wetlands (analysis of similarity, P < 0.05). Small fishes of <20 mm fed largely on microcrustaceans and may have led to low microcrustacean densities within the wetlands. This result matched our prediction that rarely flooded wetlands would be more productive; hence, they supported greater populations of microcrustaceans and cichlids, which are aggressive feeders. However, the predominance of microcrustaceans in the guts of small fishes (<20 mm) suggests that predation by fishes may also be an important regulatory mechanism of microcrustacean assemblages during large floods when inundated terrestrial patches of wetlands are highly accessible by fish. We predict that a decline in the amount of water reaching the Delta will negatively affect fish recruitment, particularly the cichlids that heavily exploited the rarely flooded wetlands. Cichlids are an important human food source, and their decline in fish catches will negatively affect livelihoods. Hence, priority in the management of the Delta’s ecological functioning should be centred on minimising natural water-flow modifications because any changes may be detrimental to fish-recruitment processes of the system.     

3-Indolepropionic acid prevented chlorpyrifos-induced hepatorenal toxicities in rats by improving anti-inflammatory,antioxidant, and pro-apoptotic responses and abating DNA damage

Environmental Science and Pollution Research - The application of chlorpyrifos (CPF), an organophosphorus pesticide to control insects, is associated with oxidative stress and reduced quality of...