基于Copula 函数的边坡可靠度高效分析方法

将Copula函数与高效蒙特卡洛方法结合,提出了含相关随机变量的边坡可靠度高效分析方法。以两个岩质边坡稳定性问题为例验证了所提方法的有效性。结果表明,该方法相比于直接蒙特卡洛方法在保证边坡失效概率的准确性的同时计算效率更高。Copula函数可以构造出具有不同相关结构的岩土体参数的联合概率分布,与高效蒙特卡洛方法(即蒙特卡洛重要抽样方法和子集模拟)结合能高效地处理含多种相关随机变量的边坡可靠度计算问题,相比于现行的Nataf变换方法结果更能体现岩土边坡真实稳定性。此外,该方法也能高效地计算含有复杂的隐式功能函数的边坡可靠度,研究成果拓展了高效蒙特卡洛方法在边坡可靠度分析中的应用。     

Genetic diversity of herbicide-resistant and -susceptible Avena fatua populations in North Dakota and Minnesota

Genetic diversity within and among 20 herbicide-resistant (HR) and 16 herbicide-susceptible (HS) Avena fatua multi-field populations was determined using 82 polymorphic loci resulting from two intersimple sequence repeat (ISSR) primers and one long-primer random amplified polymorphic DNA (LP-RAPD) primer. Collections from the Red River Valley of North Dakota and Minnesota, sampled in 1964 and 2000, represented A. fatua populations before and after intensive exposure to herbicides. A 1995 collection from south-west North Dakota represented A. fatua exposed to low herbicide selection. Despite differences in years of herbicide exposure among collections, both HR and HS populations from every collection maintained nearly similar levels of ISSR and RAPD diversity. Genetic differentiation among populations (G_ST) varied from 11% to 13% among HR populations and from 9% to 16% among HS populations, indicating that 84–91% of total variation remained within HS or within HR populations. Minimal difference in gene diversity between HR and HS is consistent with multiple origins of resistance, where HR A. fatua most likely evolved from diverse founding individuals.     

计算机软件的硬加密卡

提出了软件的一种智能硬加密方法．利用8位单片机、PCI总线结构设计了一种直接插在计算机总线上的硬件加密卡．加密程序设为中断程序，以陷阱中断的方式启动该中断程序．采用随机数实时核对加密方法，加密卡中随机数生成电路经A／D转换后、通过外部中断方式存入片内RAM中，成为被加密数．因该数是随机产生的，所以解密很困难．单片机与PC机间数据传输的端口地址译码采用GAL16V8完成，既具有保密性，又减少成本，节省了系统地址资源．     

Effect of mate selection on fuzzy selective mating criteria in closed dairy multiple ovulation and embryo transfer nucleus programs

In order to control rates of response and inbreeding, mate selection using fuzzy selective mating criteria (FMC) was investigated in adult multiple ovulation and embryo transfer nucleus schemes for dairy cattle. Stochastic simulation was used to model the closed nucleus scheme. This mate selection was examined in four alternative mating and male selection schemes: (i) a hierarchical scheme; (ii) a hierarchical sibship scheme (two males per sibship); (iii) a factorial scheme (two sires per dam); and (iv) a factorial sibship scheme (two males per sibship and two sires per dam). Genetic response and inbreeding rate tended to be reduced by increasing the trade-off parameter of FMC between the expected breeding value and inbreeding of progeny. Inbreeding rates in all schemes were reduced by reducing the variance of family size through selection and the average coancestry of mating pairs through mate allocation.     

The Biology of the Larger Grain Borer, Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae)

After about 25 years of intensive research a substantial moment of information has accumulated on the basic biology of Prostephanus truncatus in stored products. This article reviews the literature on the geographical distribution, biotypes, symbiotic associations, mating and flight behaviour, oviposition, and development on both agricultural and non-agricultural hosts. The current knowledge about the nutritional biology (including the role of symbionts) and host finding behaviour (including the inter-linked roles of plant chemicals and the insect's own pheronones) are highlighted as research areas which deserve future attention. In addition, few studies have been conducted to determine the extent to which the biology of P. truncatus permits it to survive and reproduce in non-agricultural environments. These areas of study should be pursued as possible routes to providing more effective integrated pest managements strategies for the larger grain borer.     

Potential of sexual reproduction among host-adapted populations of Phytophthora infestans sensu lato in Ecuador

To determine the potential of sexual reproduction among host-adapted populations of Phytophthora infestans sensu lato in Ecuador, 13 A1 isolates belonging to clonal lineages US-1, EC-1 and EC-3, and 11 A2 isolates belonging to the clonal lineage EC-2, were paired on agar plates to induce crossing. In the first experiment, six A1 isolates (three US-1, two EC-1 and one EC-3) were each crossed with three A2 isolates (total = 18 crosses). Matings involving isolates of the EC-1 lineage produced more oospores of healthy appearance than did matings with isolates of US-1 or EC-3. In the second experiment, the oospores of 35 crosses (21 EC-1 × EC-2; 10 US-1 × EC-2; four EC-3 × EC-2) were dispersed on water agar to assess oospore germination. Overall, germination percentages were low. Only one cross produced enough progeny for evaluation. Twenty-three single-oospore offspring were isolated and evaluated for mating type; electrophoretic patterns of glucose-6-phosphate isomerase ( Gpi ) and peptidase ( Pep ) alloenzyme loci; mitochondrial DNA haplotype; and genomic DNA fingerprint. Multilocus genotype data indicated that all 23 isolates resulted from meiotic recombination. Four progeny with homothallic phenotype appeared to be unstable heterokaryons. Markers at several loci segregated according to simple Mendelian expectations for a diploid organism, but the ratios of three RFLP loci and the Pep locus were not consistent with Mendelian expectations. All progeny were nonpathogenic on hosts of the parental genotypes. Reduced mating success and reduced pathogenic fitness of progeny appear to be postmating mechanisms of reproductive isolation in populations of P. infestans sensu lato in Ecuador.     

小菜蛾对溴氢菊酯抗药性的随机扩增多态性DNA分析

利用室内选育119代的抗溴氰菊酯小菜蛾Plutella xylostella品系和敏感品系，通过反复回交和自交建立近等基因系。用Operon公司合成的20个引物对近等基因系基因组DNA进行PCR扩增。3个引物在抗性品系中分别产生1条特异扩增带，4个引物在敏感品系中分别产生了1～5条特异扩增带。由于在近等基因系中，除了与抗性相关的基因区外，其它的遗传背景是相同的，因此可以认为这些特异带与小菜蛾对溴氰菊酯的抗性有关。     

云南省马铃薯晚疫病菌的交配型、抗药性及生理小种分布的研究

 从云南省陆良县、建水县和南涧县采集2000年秋播的马铃薯晚疫病标本,分离获得124个致病疫霉菌株,连同1999~2000年分离自昆明、曲靖等地的春播马铃薯晚疫病的10个菌株共134个,采用常规技术对这些菌株进行了交配型、抗药性及生理小种的研究。交配型测定结果为:陆良县的18个菌株中有3个为A₂交配型,其余15个菌株为A₁交配型,建水县和南涧县的106个菌株及昆明、曲靖1999~2000年的10个菌株都是A₁交配型。测定了83个菌株对瑞毒霉(metalaxyl)和烯酰吗啉(dimethomorph)的抗药性,结果有12.0%的菌株对瑞毒霉表现抗性,16.9%表现中抗,71.1%表现敏感,其中陆良、昆明和曲靖的抗瑞毒霉菌株的比例大于建水和南涧的抗药性菌株的比例;所测定的83个菌株都对烯酰吗啉表现敏感。生理小种鉴定结果表明,云南晚疫病菌为3.4、0、3和4生理小种,分别占鉴定菌株总数的48.0%、32.5%、15.6%和3.9%。但南涧仅发现3.4和0小种,而昆明有0、3、3.4和4小种,陆良有0、3和3.4小种,可见昆明和陆良地区的晚疫病菌生理小种比南涧地区的生理小种的组成更趋多样。     

猕猴桃叶片叶绿素含量高光谱估算模型研究

【目的】研究猕猴桃叶片叶绿素含量的高光谱估算方法,为猕猴桃长势的遥感监测提供理论依据。【方法】以陕西杨凌蒋家寨村2018年不同生育期(初花期、幼果期、膨果期、壮果期、果实成熟期)的猕猴桃叶片为研究对象,分别测定其高光谱反射率和叶绿素含量(SPAD值),分析原始光谱和5个常见的植被指数(归一化植被指数、归一化叶绿素指数、改进的叶绿素吸收反射率指数、MERIS地面叶绿素指数、土壤调整指数)与叶绿素含量之间的相关关系,提取各生育期的特征波段,分别建立基于特征波段和植被指数的单波段叶绿素含量一元线性估算模型。利用主成分分析对原始光谱数据进行降维,将得到的主成分得分作为随机森林模型的输入变量,建立基于多波段信息的叶绿素含量多元估算模型,并对模型进行精度验证和分析。【结果】不同生育期猕猴桃叶片光谱反射率变化趋势基本一致,整体趋势为可见光波段反射率低,近红外波段反射率高;在可见光波段,光谱反射率随着叶绿素含量的升高而降低;在近红外波段,光谱反射率则随着叶绿素含量的增加而升高。通过相关性分析可知,初花期、幼果期、膨果期、壮果期、果实成熟期原始光谱的特征波段分别为729,548,707,707和712 nm,估算模型决定系数(R~2)分别为0.18,0.85,0.54,0.85和0.82,其中初花期估算模型未通过显著性检验,其余生育期均通过极显著性检验。在5个常用植被指数中,初花期与叶绿素含量相关性最高的是归一化叶绿素指数(NPCI),但是估算模型决定系数R~2只有0.1,未通过显著性检验;其他生育期与叶绿素含量相关性最高的是MERIS地面叶绿素指数(MTCI),所建立的估算模型拟合效果好,预测精度高。基于主成分分析和随机森林回归建立的不同生育期猕猴桃叶片叶绿素含量估算模型的R~2在0.91～0.98,均通过极显著性检验,其拟合效果和预测精度远高于单波段一元线性回归和基于植被指数的一元线性回归模型,是估算猕猴桃叶片叶绿素含量的最优模型。【结论】基于主成分分析的随机森林模型包含了更完整的波段信息,对不同生育期猕猴桃叶片叶绿素含量具有较好的预测能力。