Autumn leaf colouration: a new hypothesis involving plant–ant mutualism via aphids

Several recent hypotheses on the adaptive significance of autumn leaf colours have focused on specialist aphids. However, these hypotheses have overlooked several factors: the preferential investment by healthy vigorous trees in growth rather than defence against herbivores, variation among aphid species in their responses to bright autumn leaves and plant defences and the occurrence of tritrophic interactions in tree crowns. I incorporate these factors into a hypothesis that autumn leaf colours signal tree quality to myrmecophilous specialist aphids, with the aphids, in turn, attracting aphid-tending ants during the following spring, and the ants defending the trees from other aphids and herbivores. Therefore, bright autumn leaves may have adaptive significance, attracting myrmecophilous specialist aphids and their attending ants and, thus, reducing herbivory and competition among aphids.     

Effects of an Alien Ant Invasion on Abundance,Behavior, and Reproductive Success of Endemic Island Birds

Abstract: Biological invaders can reconfigure ecological networks in communities, which changes community structure, composition, and ecosystem function. We investigated whether impacts caused by the introduced yellow crazy ant (Anoplolepis gracilipes), a pantropical invader rapidly expanding its range, extend to higher‐order consumers by comparing counts, behaviors, and nesting success of endemic forest birds in ant‐invaded and uninvaded rainforest on Christmas Island (Indian Ocean). Point counts and direct behavioral observations showed that ant invasion altered abundances and behaviors of the bird species we examined: the Island Thrush (Turdus poliocephalus erythropleurus), Emerald Dove (Chalcophaps indica natalis), and Christmas Island White‐eye (Zosterops natalis). The thrush, which frequents the forest floor, altered its foraging and reproductive behaviors in ant‐invaded forest, where nest‐site location changed, and nest success and juvenile counts were lower. Counts of the dove, which forages exclusively on the forest floor, were 9–14 times lower in ant‐invaded forest. In contrast, counts and foraging success of the white‐eye, a generalist feeder in the understory and canopy, were higher in ant‐invaded forest, where mutualism between the ant and honeydew‐secreting scale insects increased the abundance of scale‐insect prey. These complex outcomes involved the interplay of direct interference by ants and altered resource availability and habitat structure caused indirectly by ant invasion. Ecological meltdown, rapidly unleashed by ant invasion, extended to these endemic forest birds and may affect key ecosystem processes, including seed dispersal.     

城镇油气管道事故应急疏散决策优化

为实现油气管道事故中城镇大规模应急疏散的智慧决策,构建基于改进的自适应蚁群算法的应急疏散路径优化模型,开发基于油气管道典型事故后果分析的城镇大规模应急疏散决策优化系统平台(LSSED)。LSSED在地理信息系统平台上,针对油气管道泄漏引起的扩散、喷射火、池火、BLEVE、蒸气云爆炸等典型事故进行事故后果分析,对疏散通道当量长度和疏散时间成本函数进行定量评价,实现大规模应急疏散方案的智慧决策和避难方案的全局优化。案例分析表明,LSSED平台实现了基于地理信息系统的典型事故时变环境信息和应急疏散路径优化算法的数据传递及系统集成,实现了基于事故后果分析的城镇大规模人群疏散路径和避难方案优化,可为城镇安全规划和应急管理提供参考和借鉴。     

酵母双杂交技术构建重组人雌激素受体基因酵母

应用酵母双杂交技术构建重组人雌激素受体基因酵母,用以检测类/抗雌激素化合物和环境样品的类/抗雌激素活性.采用多聚酶链反应(PCR)法扩增人雌激素受体(hER)基因,构建诱饵质粒pGBKT7-ER LBD;分别提取并纯化两种含有ER共激活因子基因的靶质粒pGAD424-GRIP1和pGAD424-SRC1;诱饵质粒和靶质粒同时转染酵母细胞Y187,于营养缺陷型培养基(SD/-Trp/-Leu)上筛选阳性菌落,分别构建两种ER双杂交酵母ER+GRIP1和ER+SRC1.考察双杂交酵母与不同激素:17β-雌二醇(E2)、二氢睾酮(DHT)、孕酮(PG)以及三碘甲状腺原氨酸(T3)的结合情况,并考察了雌激素受体拮抗剂4-羟基他莫昔芬(4-OHT)与酵母的相互作用.结果表明:ER+GRIP1和ER+SRC1酵母均能够专一性的和E2结合,并存在显著的剂量-效应关系,E2对ER+GRIP1和ER+SRC1酵母β-半乳糖苷酶活性诱导的EC50值分别为7.3×10-11mol·L-1和1.5×10-10mol·L-1,其中ER+GRIP1酵母细胞诱导产生的酶活性值明显高于ER+SRC1酵母细胞.4-OHT能够抑制E2诱导ER+GRIP1酵母细胞产生的酶活性,并存在显著的剂量-效应关系,IC50值为1.0×10-7mol·L-1.表明重组人雌激素受体基因酵母可以用于检测化合物和环境样品的类/抗雌激素活性.     

基于蚁群神经网络的煤矿瓦斯预测模型

为了提高煤矿瓦斯涌出量的预测精度和预测速度,用蚁群算法和神经网络相结合的方法进行预测模型设计。选择瓦斯涌出的重要影响因素,建立其神经网络的预测模型。以网络的均方误差为目标函数,通过蚁群算法的迭代运算,实现BP网络的权值优化,并用优化好的BP网络进行瓦斯涌出预测。仿真结果表明,该方法具有较高的拟合预测精度。     

多碍航物水域救援船路径规划方法

为提升救援船在复杂环境中的适用性,基于安全距离约束法和改进蚁群算法,提出一种救援船路径规划方法。首先,根据救援船的初始位置和目标位置确定目标水域范围,运用栅格法将水域环境划分为可航水域和不可航水域,并通过安全距离约束的方法保障救援船与碍航物间的最小安全距离;然后,优化信息素初始浓度、启发因子和挥发因子,设置期望值启发因子和距离启发函数,改进蚁群算法,提升算法搜索的目的性和快速性,并将其运用于栅格地图中,规划救援船的路径;最后,选取舟山群岛附近水域作为试验水域,以东海救102救援船为试验船舶进行验证。结果表明:与传统方法相比,所提出的救援船路径规划方法收敛速度更快,且给出的路径长度更短,转向点更少,运行时间更短;该方法能够克服救援船路径规划过程中面临的收敛速度慢和局部最优问题,增强鲁棒性。     

基于自适应调整蚁群-RBF神经网络模型的中长期径流预测

径流预测历来是水利部门的一项重要工作,针对水库和河流中长期径流预测精度不高,提出了自适应调节人工蚁群算法(ARACS),对RBF神经网络参数进行优化,建立了自适应调节人工蚁群-RBF神经网络组合算法(ARACS-RBF)预测模型,综合考虑影响径流预变化因素,对安康水库进行中长期径流预测。对预测效果进行检验,结果证实该模型可真实地反映河川径流变化的总体趋势, 并为判断时间序列数据的非线性提供了一种新方法。与RBF神经网络模型、人工蚁群-RBF神经网络模型预测结果进行对比,结果表明,应用ARACS-RBF模型对中长期径流量进行预测,预测精度更高、效果更好。该方法克服了RBF神经网络和人工蚁群算法易陷于局部极值、搜索质量差和精度不高的缺点,改善了RBF神经网络的泛化能力,收敛速度快,输出稳定性好,提高了径流预测的精度,置信度为98%时的预测相对误差小于6.5%。可有效用于水库和河川中长期径流预测。     

基于蚁群算法的商业步行街应急疏散决策优化*

为分析基于决策优化的应急疏散方案引导下,商业步行街发生突发事件时大规模人群应急疏散的安全性,以某商业步行街为例,利用改进的自适应蚁群算法,进行疏散决策优化和疏散方案的优化设计;结合Pathfinder软件对基于优化疏散方案的人员疏散行为进行数值模拟,对比分析决策优化前后商业步行街大规模人群疏散的效率和安全性。结果表明:基于优化疏散方案对大规模人群进行疏散,在无火灾环境下疏散效率提高了8.86%;在火灾环境下疏散效率提高了6.57%。基于大规模应急疏散决策优化的应急疏散方案可有效缓解部分安全出口的人员群集滞留状况,实现应急疏散决策的全局优化。     

带时间窗的危险货物车辆路径问题2阶段优化

为有效降低危险货物道路运输的风险和成本,针对带时间窗的危险货物车辆路径问题(HMVRPTW),设计2阶段优化方法。首先,根据特征将该问题分解为双目标最短路径问题和带时间窗双目标车辆路径问题(VRP),分别建立数学模型并设计2阶段方法求解,第1阶段采用脉冲算法初筛路径,第2阶段设计针对带时间窗双目标VRP蚁群算法;然后,以9个节点和17条边的测试为例,说明求解过程;最后,以兰州市主城区16个加油站油品配送为例,采用该方法分配运输车辆,计算平均用时为24.38 s,可获得Pareto最优解,而采用多目标遗传算法平均用时为41.05 s。结果表明:所提方法通过初筛路径能够简化问题规模,充分考虑危险货物运输风险变化及时间窗因素,引导蚂蚁在指定搜索空间中寻优,在效率方面较多目标遗传算法具有明显优势。