Who hits and hoots at whom? Potential for interference competition between barred and northern spotted owls

The northern spotted owl (Strix occidentalis caurina) is a controversial species in the Pacific Northwest that is listed as threatened under the Endangered Species Act. The barred owl (Strix varia), a species historically restricted to eastern North America, has recently expanded its range to completely overlap that of the northern spotted owl. Recent evidence suggests that barred owls may compete with northern spotted owls and may be one cause for recent declines in some northern spotted owl populations. Our focus was to examine whether barred owls have the potential to competitively exclude northern spotted owls from their territories through interference competition. We used a playback experiment to quantify aggressive vocal and physical behavior of barred and northern spotted owls during territorial defense. Experimental trials consisted of displaying northern spotted or barred owl taxidermy mounts, and broadcasting recorded vocalizations of the corresponding species, in both barred and northern spotted owl territories. The frequency of interspecific interactions was lower compared to intraspecific interactions between northern spotted owls alone. However, barred owls responded with higher levels of vocal and physical aggression than did northern spotted owls when agonistic interspecific interactions occurred. Our results suggest that barred owls are likely to assume the dominant role during interspecific interactions with northern spotted owls. Thus, interference competition is a plausible mechanism by which barred owls could contribute to observed population declines of northern spotted owls in areas where the species co-occur.     

面向单点渐进成形工艺的成形路径生成方法

在分析单点渐进成形工艺特点的基础上,指出该工艺成形路径生成目前存在的问题,提出了一种面向该工艺的成形路径计算方法,及基于该方法的等高线成形路径生成算法。上述方法已应用到日本Amino公司单点渐进成形设备专用的工艺规划软件AFS2中,实际加工得到的零件表面具有较高质量。有限元模拟结果及试验结果表明,采用该算法生成的成形路径合理可行。     

邻体干扰指数模型的改进及其应用研究

在前人研究工作基础上提出邻体干扰指数的改进模型H.,以马尾松人工林邻体干扰为对象探讨了改进模型的具体应用,并与前人提出的主要模型进行了比较分析.实例应用结果表明,改进的指数模型能够解释马尾松人工林生长速度变异的83%左右,因此可以说改进模型优于原先的指数模型,具有更大的适用性和灵活性,可在植物邻体干扰研究中应用.马尾松人工林邻体干扰的灵敏度分析表明,基株大小对邻体干扰指数的影响较邻体大小和基株到邻体之间距离更灵敏,是决定邻体干扰的主要因素.     

Interference by amino acids during the determination of N ammonium in soil

In the study of terrestrial N cycling, NH₄⁺ concentration and ¹⁵N enrichment are routinely determined by colorimetric continuous flow analysis and microdiffusion methods. Amino acids can interfere in these determinations; consequently the aim of the present study was to evaluate the significance of the interference. Glycine and glutamine are key amino acids in soil and were therefore used as ‘models’. Both glycine and glutamine interfered during continuous flow analysis, whereas interference during microdiffusion was of little importance. The effects of interference can be significant, e.g. estimates of gross mineralisation rate were reduced up to 33%, where we allowed for amino acid interference during determination of NH₄⁺ concentration. The potential influence of amino acid interference emphasises that development of continuous flow analysis to increase NH₄⁺ specificity is needed.     

邻体干扰改进模型在竹类研究中的利用——以小蓬竹为例

依据改进的邻体干扰模型,利用喀斯特适生竹种小蓬竹样地实际调查的基株与邻体的数据,研究基株竹高、冠幅以及枝下高与干扰指数的关系,结果表明:基株的冠幅、树高与枝下高与干扰指数之间呈显著的负相关关系。不同样地因为密度不同,相同因子相同数值决定的干扰指数不一样。该研究结果为合理营造和经营竹类林分提供理论依据。     

数控车床实习中减少事故的方法

文章介绍了一些在数控车床实习中减少安全事故的方法,有利于提高数控车床实习安全性,降低安全事故发生率,保证数控实习教学的顺利进行.     

禽呼肠孤病毒σNS和σC基因shRNA载体构建及其干扰效果测定

禽呼肠孤病毒σC基因是病毒粘附蛋白,σNS基因具有结合单链RNA活性。根据siRNA靶序列设计原则,设计并合成siRNA模板并克隆到shRNA表达载体pSilencer-CMV 4.1 neo。分别构建了针对σC基因的shRNA载体C1、C2、C3和针对σNS基因的shRNA载体NS1、NS2、NS3。将构建的shRNA载体和阴性对照分别与表达σC和σNS基因的融合蛋白的真核表达载体pEGFP-σC及pEGFP-σNS共转染DF-1细胞。荧光显微镜观察结果表明,6个shRNA片段不同程度地抑制各自融合蛋白的表达。Real-time PCR检测结果表明,C3和NS1体外干扰病毒复制的效果最佳。     

细叶百合的生殖特性和繁育规律研究

 研究结果表明, 栽培条件下2年生细叶百合实生苗中不抽茎、抽茎不开花和开花的比例分别为: 38.79% , 47.66%和13.55%。3年生和4年生细叶百合全部开花, 且开花比例随栽培年龄增加而增大。花粉和胚珠比为: 栽培164.9～175.2; 野生284.4～315.6, 其繁育系统为兼性自交。全光栽培下, 相对生殖成功率随植株年龄增加而增大, 2年生植株, 全光条件的相对生殖成功率是林下的7.5倍; 野生与全光下的相对生殖成功率相差无几。在开花前5 d其柱头即有可授性, 花前1 d授粉的结实率最高。细叶百合无多父本效应, 单一父本结实率和种子产量反而较高。人工同株异花、自花授粉坐果率为自然传粉坐果率的1 /2左右, 毛百合及松叶百合的花粉对其生殖有很强的干扰作用。     

新型珠光颜料—云母钛

本文简述了珠光颜料的主要类型及特性。着重介绍了云母钛珠光颜料的制法、特性、应用及发展。并概要地讨论了云母钛珠光颜料的结构及干涉色与二氧化钛色膜厚度及拄度间的关系。     

龟纹瓢虫对苜蓿蚜的捕食效应(简报)

苜蓿蚜(Aphis medicaginis Koch)又名豆蚜、花生蚜、槐蚜等,是危害豆科牧草苜蓿(Medicago sativa)、沙打旺(Astragalus adsurgens)等的主要害虫之一,每年6、7月在苜蓿上大发生,受害植株长势慢,枝叶畸形化,使豆荚畸形变小,籽粒减少,导致植株提前死亡,影响其作为饲草品质与产量,对苜蓿产业构成严重威胁。