牛科(哺乳纲:偶蹄目)动物与食物有关的适应形态模式

利用逐步分辨分析方法（Stepwise discriminant analysis,SCDA）检测了广义牛科动物的颅齿部结构,这些结构特征可以作为采食行为生态适应特征。在本研究中,测量了72种广义牛科动物的28个颅齿部结构。逐步分辨分析方法得出了6种采食方式适应类型：一般粗食者、新鲜禾草粗食者、开阔生境混合型采食者、精食者、郁闭生境混合型采食者、食果者。用103个标本检测了分辨指标的预测能力,所用标本为缺损标本,大多数缺少一项或多项结构。从这些标本获得的分辨函数的平均预测能力为94％,比用72种广义牛科动物标本建立的分辨函数的平均预测能力（98％）低一些。从一个颅齿部结构小样本建立的分辨函数可以用于考古发掘物中不完整标本的研究。这些指标与用颅下结构测量建立的运动能力和生境选择的指标相结合,可以推断古牛科动物的个体生态学以及古环境重建。     

Stepwise gatekeeping procedures in clinical trial applications

This paper discusses multiple testing problems in which families of null hypotheses are tested in a sequential manner and each family serves as a gatekeeper for the subsequent families. Gatekeeping testing strategies of this type arise frequently in clinical trials with multiple objectives, e.g., multiple endpoints and/or multiple dose-control comparisons. It is demonstrated in this paper that the parallel gatekeeping procedure of Dmitrienko, Offen and Westfall (2003) admits a simple stepwise representation (n null hypotheses can be tested in n steps rather than 2n steps required in the closed procedure). The stepwise representation considerably simplifies the implementation of gatekeeping procedures in practice and provides an important insight into the nature of gatekeeping inferences. The derived stepwise gatekeeping procedure is illustrated using clinical trial examples.     

Bonferroni parallel gatekeeping - transparent generalizations, adjusted p -values, and short direct proofs

In the two-step version (Dmitrienko, Tamhane, Wang and Chen, 2006) of the Bonferroni parallel-gatekeeping multiple-testing procedure (MTP): (a) a family F1 of null hypotheses H is used as a gatekeeper for another family F2 in that no H in F2 can be rejected unless at least one H is rejected in F1; (b) a Bonferroni MTP is used for F1 at local multiple-level alpha in the first step; and (c) Holm's (1979) step-down MTP is used in the second step for F2 at a local multiple level that depends on the rejections made in the first step. It is shown in this article that this two-step procedure can be generalized in that any MTP with multiple-level control and available multiplicity-adjusted p -values can be used instead of Holm's MTP in the second step. A further generalization related to what Dmitrienko, Molenberghs, Chuang-Stein and Offen (2005) called modified Bonferroni parallel gatekeeping is also given where in case all H s in F2 are rejected, additional rejections in F1 can be made in a third step at local multiple-level alpha through any MTP that is more powerful than the initial Bonferroni MTP, e.g. Holm's MTP. The proofs that these two generalized Bonferroni parallel-gatekeeping MTPs have multiple-level alpha are short and direct, without closed-testing arguments. Multiplicity-adjusted p -values can easily be calculated for these MTPs. The extensions to several successive gatekeeper families are straightforward. An illustration is given.     

Analytical grade C-phycocyanin obtained by a single-step purification process

C-phycocyanin (C-PC) is a phycobiliprotein that can be used as a natural blue dye in the food and cosmetic industries, as a biomarker or as an agent in medical treatments, depending on its purity grade. Here we described for the first time a single-step purification process of C-PC extracted from the wet biomass of Spirulina (Arthrospira) platensis LEB-52 using ion exchange chromatography with pH gradient elution. Different conditions varying the elution buffers and volumes, the loading pH and the addition of salt in the elution buffer were studied. The chromatographic condition that resulted in high recovery and purity consisted in equilibration and washing with 0.025 mol/L Tris-HCl buffer pH 6.5 and elution combining a step with 0.08 mol/L NaCl in 0.025 mol/L Tris-HCl buffer pH 6.5 and a pH gradient elution with 0.05 mol/L citrate buffer pH 6.2–3.0. This process resulted in C-PC with purities of 4.2 and 3.5 with recoveries of 32.6 and 49.5 %, respectively, in one purification step.     

Effects of variable hydroperiods and water level fluctuations on denitrification capacity, nitrate removal, and benthic-microbial community structure in constructed wetlands

The hydrologic character of wetlands is one of the attributes by which they are defined. There are, however, conflicting reports about the detrimental versus beneficial responses of wetland systems to water level fluctuations and variable hydroperiods. We conducted water level and hydroperiod fluctuation studies in full-scale experimental wetlands in order to determine the effects of hydraulic operation on wetland performance (in terms of nutrient removal), and benthic-bacterial community function (in terms of denitrification potential, DNP) and structure (via terminal restriction fragment length polymorphisms, T-RFLP). In our comparison, detention time was the controlling factor for nitrate removal at the system level. However, widely fluctuating water levels and variable hydroperiods did not diminish either the nitrate removal capacity of the experimental wetlands, or the size or composition of benthic-bacterial communities relative to the more stable water level systems. Rather, significant differences in denitrification potential rates, bacterial cell densities, and benthic community structure were a function of sampling location within the experimental wetlands regardless of hydraulic operation. The results of this study support the need for reconsidering the hydraulic criteria for wetland delineation.     

A Phylogenetic Perspective on Sequence Evolution in Microsatellite Loci

We examined the evolution of the repeat regions of three noncoding microsatellite loci in 58 species of the Polistinae, a subfamily of wasps that diverged over 140 million years ago. A phylogenetic approach allows two new kinds of approaches to studying microsatellite evolution: character mapping and comparative analysis. The basic repeat structure of the loci was highly conserved, but was often punctuated with imperfections that appear to be phylogenetically informative. Repeat numbers evolved more rapidly than other changes in the repeat region. Changes in number of repeats among species seem consistent with the stepwise mutation model, which is based on slippage during replication as the main source of mutations. Changes in repeat numbers can occur even when there are very few tandem repeats but longer repeats, especially perfect repeats led to greater rates of evolutionary change. Species phylogenetically closer to the one from which we identified the loci had longer stretches of uninterrupted repeats and more different motifs, but not longer total repeat regions. The number of perfect repeats increased more often than it decreased. However, there was no evidence that some species have consistently greater numbers of repeats across loci than other species have, once ascertainment bias is eliminated. We also found no evidence for a population size effect posited by one form of the directionality hypothesis. Overall, phylogenetic variation in repeat regions can be explained by adding neutral evolution to what is already known about the mutation process. The life cycle of microsatellites appears to reflect a balance between growth by slippage and degradation by an essentially irreversible accumulation of imperfections. Received: 13 April 1999 / Accepted: 8 September 1999     

侧位X片上颅内面积的研究—其逐步回归方程式与评价

本文对１８－７６岁正常成人１０４人（男６７,女３７）的Ｘ线颅侧位片进行了颅最大长（Ｘ１）、颅高（Ｘ２）、颅底长（Ｘ３）、鼻根点－枕外隆凸点长（Ｘ４）、耳上颅高（Ｘ５）、颅矢状弧（Ｘ６）和侧位片上颅腔面积（Ｙ）的测量,用电子计算机对数据进行了逐步回归分析处理,筛选出推算颅腔侧面积的最佳因子Ｘ１、Ｘ２和Ｘ４。它们之间呈正相关关系,其复相关系数Ｒ＝０．６２,Ｐ〈〈０．０００５,相关系数有高度显著性。故建     

A two-stage stepwise estimation procedure

Summary .   This article proposes a two-stage simultaneous confidence procedure for the comparisons of k pairs of population means, without using multiplicity adjustment of more than two populations. The proposed procedure can be broadly applied to parametric or nonparametric models. It is robust and versatile because its derivation only utilizes a partitioning approach in conjunction with a bivariate adjustment, without any assumption on the underlying distribution. To elucidate the application, the proposed procedure is intertwined with the estimation of the therapeutic window of a drug. It provides confidence limits for the efficacy and the toxicity of the effective doses, highest ineffective dose, safe doses, and lowest unsafe dose, simultaneously. Such estimation information facilitates follow-up studies in clinical trials. As an illustrative example, the new procedure is applied to analyze a data set on molecular cancer therapeutics regarding the apoptotic killing effects of different chemical compounds on two leukemia cell lines.     

陕西黄龙山林区褐马鸡春季觅食地选择

2006年4～5月,在陕西黄龙山林区采用样带法对褐马鸡(Crossoptilon mantchuricum)春季觅食地选择进行了研究.共测定了9条样带上的54个随机样方和54个栖息地利用样方的20个生态因子.结果表明,褐马鸡春季觅食期间偏好利用针阔混交林,避免针叶林和阔叶林;偏向于下坡位,避免上坡位和中坡位;偏向于中等坡度的山坡(10～20°),避免坡度较大和较小的山坡;对坡向没有明显的选择性.对利用样方和随机样方进行比较,发现利用样方具有海拔较低、与林间小路和水源较近、乔木种类较少、乔木密度较小、乔木最大胸径较大、乔木最大高度较高、灌木种类较少、灌木密度较小、食物丰富度较大、灌木层植物盖度较小、乔木层植物盖度较大、隐蔽级较小等特征.逐步判别分析表明,乔木密度、与水源距离、灌木密度、灌木种类、乔木最大高度、海拔具有重要作用,由这6个变量构成的方程在对繁殖季节觅食地利用样方和对照样方进行区分时,正确判别率可以达到97.22%.褐马鸡春季觅食地选择主要与食物条件、隐蔽条件和水源有关.