厌氧混合培养条件下六氯苯生物降解的外加碳源必要性

采用标准血清瓶实验探讨了厌氧污泥对六氯苯(HCB)的降解活性以及各种环境因素的影响.结果表明,经过14d的HCB驯化,厌氧污泥具备了较好的降解HCB能力;反应温度对HCB的降解速率有很大影响,适宜温度为35℃左右;葡萄糖、甲酸、乙酸、丙酸和丁酸等有机碳源的存在明显促进了HCB的厌氧降解,其中甲酸和乙酸的加入极其重要;根据实验结果推测出,产甲烷过程对HCB的生物降解发挥了重要作用.     

Statistical Estimation and Model Selection of Species-Accumulation Functions

Abstract:  Soberón and Llorente (1993) proposed pure-birth stochastic processes as theoretical models for species-accumulation curves, and these processes have frequently been used to describe the progress of biological inventories. We describe, in algorithmic form, an alternative statistical analysis based on a likelihood approach ( Díaz-Francés & Gorostiza 2002 ) that provides mathematical rigor to the ideas in Soberón and Llorente (1993) and improves the estimation of the models by incorporating the facts that the variance of the error is not constant and that the observations are correlated. Additionally, we used the likelihood ratios between candidate models as an objective procedure for model selection, allowing comparison between the goodness of fit of various models. The software for these statistical methods can now be downloaded off the Internet. We used two examples of butterfly data sets to illustrate the use of the methods and the software.     

环境因素对六氯苯厌氧降解活性的影响

在厌氧污泥具备了较好的六氯苯（HCB）降解能力的基础上,采用标准血清瓶实验方法考察了反应温度、初始pH、摇床转速和营养元素等环境因素对厌氧污泥降解HCB活性的影响。实验设计的反应温度为25、30、35和40℃;初始pH为5.0、6.0、7.0和8.0;摇床转速为0和150r·min-1;营养元素有葡萄糖和维生素b12。用HCB浓度随时间的减少来表征微生物对其的降解活性。结果表明,反应温度对HCB的降解速率有很大影响,适宜温度为35℃左右。初始pH对HCB降解活性没有显著影响,但显示出有随初始pH增大而HCB降解活性增加的趋势。与静置条件相比,一定的混合作用有利于提高HCB的降解活性。有葡萄糖存在条件下,维生素b12对HCB的降解活性有明显的促进作用。温度及外加碳源（葡萄糖）是影响HCB厌氧降解活性的重要因素,并推测葡萄糖在HCB降解过程中提供电子供体方面发挥了重要作用。     

自适应神经网络在确定落煤残存瓦斯量中的应用

落煤残存瓦斯量的确定是采掘工作面瓦斯涌出量预测的重要环节，它直接影响着采掘工作面瓦斯涌出量预测的精度，并与煤的变质程度、落煤粒度，原始瓦斯含量、暴露时间等影响因素呈非线性关系，人工神经网络具有表示任意非线性关系和学习的能力，是解决复杂非线性，不确定性和时变性问题的新思想和新方法，基于此，作提出自适应神经网络的落煤残丰瓦斯量预测模型，并结合不同矿井落煤残存瓦斯量的实际测定结果进行验证研究，结果表明，自适应调整权值的变步长BP神经网络模型预测精度高，收敛速度快，该预测模型的应用可为采掘工作面瓦斯涌出量的动态预测提供可靠的基础数据，为采掘工作面落煤残存瓦斯量的确定提出了一种全新的方法和思路。     

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.     

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。     

Modelling predation by transient leopard seals for an ecosystem-based management of Southern Ocean fisheries

Correctly quantifying the impacts of rare apex marine predators is essential to ecosystem-based approaches to fisheries management, where harvesting must be sustainable for targeted species and their dependent predators. This requires modelling the uncertainty in such processes as predator life history, seasonal abundance and movement, size-based predation, energetic requirements, and prey vulnerability. We combined these uncertainties to evaluate the predatory impact of transient leopard seals on a community of mesopredators (seals and penguins) and their prey at South Georgia, and assess the implications for an ecosystem-based management. The mesopredators are highly dependent on Antarctic krill and icefish, which are targeted by regional fisheries. We used a state-space formulation to combine (1) a mark-recapture open-population model and individual identification data to assess seasonally variable leopard seal arrival and departure dates, numbers, and residency times; (2) a size-based bioenergetic model; and (3) a size-based prey choice model from a diet analysis. Our models indicated that prey choice and consumption reflected seasonal changes in leopard seal population size and structure, size-selective predation and prey vulnerability. A population of 104 (90–125) leopard seals, of which 64% were juveniles, consumed less than 2% of the Antarctic fur seal pup production of the area (50% of total ingested energy, IE), but ca. 12–16% of the local gentoo penguin population (20% IE). Antarctic krill (28% IE) were the only observed food of leopard seal pups and supplemented the diet of older individuals. Direct impacts on krill and fish were negligible, but the “escapement” due to leopard seal predation on fur seal pups and penguins could be significant for the mackerel icefish fishery at South Georgia. These results suggest that: (1) rare apex predators like leopard seals may control, and may depend on, populations of mesopredators dependent on prey species targeted by fisheries; and (2) predatory impacts and community control may vary throughout the predator's geographic range, and differ across ecosystems and management areas, depending on the seasonal abundance of the prey and the predator's dispersal movements. This understanding is important to integrate the predator needs as natural mortality of its prey in models to set prey catch limits for fisheries. Reliable estimates of the variability of these needs are essential for a precautionary interpretation in the context of an ecosystem-based management.