联立方程模型在作物栽培技术上的应用

本文应用联立方程模型,建立了威优青杂交早稻的农艺措施与每公顷产量、每公顷有效穗数、每穗实粒数、千粒重四项生态指标间的联立方程模型,使之比相应的正交旋转回归模型更符合实际情况,并应用此联立模型给出了产量≥9000kg／ha的最适宜的栽培方案,依此可以更有效地指导生产,以获得高产．     

On the statistical analysis of multiple-choice feeding preference experiments

A stopping rule for an experiment defines when (under what conditions) the experiment is terminated. I investigated the stopping rules used in numerous multiple–choice feeding-preference experiments and also examined a recently proposed method for analyzing the data arising from such experiments. All of the surveyed experiments imposed stopping rules which result in a random total food consumption. If an acceptable quantification of preference is relative consumption of different food types, then the proposed analysis will likely misstate the information about preference conveyed by the data. This is due to the fact that the method may confound differences in preferences among food types with differences in the total consumption across trials. I discuss this issue in detail and present an alternative procedure which is appropriate under all stopping regimes when preference is quantified through relative consumption. The procedure I suggest uses an index which is a multivariate generalization of the preference index suggested by Kogan and Goeden (Ann Entomol Soc 1970; 63: 1175–1180) and Kogan (Ann Entomol Soc 1972; 65: 675–683) and which is analogous to a selection index for discrete food units proposed by Manly (Biometrics 1974; 30: 281–294). Received: 29 November 1997 / Accepted: 20 April 1998     

On randomization testing in vegetation science: multifactor comparisons of relevé groups

Abstract. Hypothesis testing in phytocoenological applications is likely to be hindered when based on conventional statistical methods. The problem created by unrealistic assumptions can, however, be overcome by randomization. This paper discusses the general idea of randomization testing, describes a method and interprets its application in group comparisons. Two sets of variables are involved, the vegetation set on the basis of which the groups are compared and the environmental factors which delimit the groups under different analytical designs. Although simple partitioning of sum of squares is at the core of the test, the method has versatility of testing uni- or multifactor designs, which is novel in phytocoenological applications. The algorithm has been implemented in programs SYNCSA and MULTIV by V.P. Data from the Campos of southern Brazil are used for illustration.     

Cloning of highly polymorphic microsatellites in the horse

We have isolated equine microsatellites by screening a genomic library with (TG)n and (TC)n probes. TG microsatellites were found to be more abundant than TC repeats, with an estimated frequency of one per 100,000bp. Sequence analysis of eight TG-positive clones revealed varying structures of the repeat regions; perfect stretches of TG repeats, imperfect stretches of TG repeats and compound regions of TG and TC repeats. Five loci were analysed by PCR and showed extensive polymorphism; three to seven alleles and heterozygosities of 0.40-0.76 were observed when screening 20-30 unrelated individuals. The high degree of polymorphism, their abundance and the possibility of automating the typing procedure make these loci ideal for standardized paternity testing in the horse. Furthermore, we demonstrate that single hairs can be used as starting material for the PCR analysis.     

Stomach lysozyme gene of the langur monkey: Tests for convergence and positive selection

Summary Genomic blotting and enzymatic amplification show that the genome of the langur monkey (like that of other primates) contains only a single gene for lysozymec, in contrast to another group of foregut fermenters, the ruminants, which have a multigene family encoding this protein. Therefore, the langur stomach lysozyme gene has probably evolved recently (i.e., within the period of monkey evolution) from a conventional primate lysozyme. The sequences of cDNAs for the stomach lysozyme of langur and the conventional lysozymes of three other Old World monkeys were determined. Identification of the promoter for the stomach gene and comparison to the human gene, which is expressed conventionally in macrophages, show that both lysozyme genes use the same promoter. This suggests that the difference in expression patterns is due to change(s) in enhancer or silencer regulatory elements. With the cDNA sequences the hypothesis that the langur stomach lysozyme has converged in amino acid sequence upon the stomach lysozymes of ruminants is tested. Consistent with the convergence hypothesis, only those sites that specify amino acids in the mature lysozyme are shared uniquely with ruminant lysozyme genes. None of the silent sites at third positions of codons or in noncoding regions support a link between the langur and ruminants. Statistical analysis based on silent sites rules out the possibility of horizontal transfer of a stomach lysozyme gene between the langur and ruminant lineages and supports the close relationship of the langur lysozyme gene to that of other monkeys.     

应用非序列联配方法对哺乳动物系统发育关系的探讨

非序列联配的序列分析方法,将序列中特定寡聚核苷酸的kmer统计频率作为特征,在序列间按特征进行比较和分析。这种方法综合考虑了所有变异类型对序列整体特征的影响,因而在组学数据分析上有独特的优势。但是,这类方法在复杂多细胞生物基因组系统发育中的适用性仍然有待检验。在本文中,我们使用基于非序列联配方法的CVTree软件,以45种哺乳动物的蛋白质组数据建立了系统发育关系NJ树,并据此探讨了哺乳动物系统发育的若干问题。在广受关注的真兽下纲四个总目的关系问题上,CVTree支持形态学的普遍结论即上兽类(Epitheria)假说。这与基于序列联配方法支持的外非洲胎盘类(Exafro-placentalia )假说不同。在哺乳动物内部目的层次上,CVTree树的结论与分子和形态所普遍接受的系统发育关系基本一致。但是在目的内部,CVTree树会有较多的差异。研究结果初步显示非序列联配方法在使用复杂多细胞生物的组学数据进行系统发育关系分析中的可行性。对非序列联配方法自身的改进及其与传统基于取代的序列联配方法之间的比较仍有待深入研究。     

基于ST-PCA-BP神经网络的檀香叶片全氮含量无损检测

氮素是植物生长需要的大量元素之一,生产经营者在植物生长过程中往往施加大量的氮肥,但过量的肥料会造成地下水污染.本文针对珍贵树种檀香,提出了一种基于ST-PCABP神经网络的檀香叶片全氮含量无损检测方法,为檀香的经营培育提供参考.结果表明:将野外获取到的檀香图像由RGB转换到L~*a~*b~*系统,可以较好地完成自然图像中的檀香分割.这是由于L~*a~*b~*系统色域宽,受光照变化的影响较小.ST-PCA-BP神经网络的特点是通过显著性检验(ST)筛选变量,使用方差膨胀因子和条件指数分析筛选结果的共线性,主成分分析法(PCA)消除共线性.该处理方法有效地减小了BP神经网络陷入局部最小值的概率,与原始数据、ST处理和PCA处理相比,决定系数最高,平均残差和均方根误差最小,是檀香叶片全氮含量无损、实时检测的最佳方法.