用地理信息系统实现舞毒蛾危害的预测(英文)

本文提出了预测舞毒蛾危害造成树木失叶的逻辑斯蒂回归模型。数据调查是以100m×100m为一格的小尺度下进行的,回归自变量是卵密度、雄蛾密度、前一年的失叶情况和到前一年最近的失叶格的距离,预测结果是一个失叶概率的分布图。我们用文中模型模拟了目前舞毒蛾综合管理中的防治决策过程,结果表明本文提出的模型在应用于实际的管理决策中是很合适的。     

A critique of silvicultural approaches to managing defoliating insects in North America

1 A variety of silvicultural techniques have been suggested for managing forest defoliating insects. The objectives focus on minimizing defoliation or minimizing damage from defoliation. 2 The theoretical foundations of many approaches have been built upon observation and correlation, and very little reliable empirical evidence exists to support the objectives of silvicultural manipulations. Existing experimental data have yielded inconsistent results. 3 We review the conceptual framework and underlying assumptions of the major silvicultural approaches recommended or in use in North America. 4 Well‐designed, long‐term studies are needed to clarify the effect of silviculture on defoliators and their effect on forests.     

具有附加信息的一种线性模型的理论

文〔1〕在研究树木材积与胸径或树高的关系时,应用了具有附加信息的一种线性模型（称为随机限制模型）．本文对这种模型从理论上进行了研究,得到了统计量H及τ的分布密度函数,给出了分位数H-α及τ-α的简单近似算法,并证明了其合理性．     

具常投放率的反应扩散系统的渐近性质

本文研究一类具常投放率的人口动力学中反应扩散系统的Neumann初边值问题,应用比较函数讨论其解的渐近性态,给出稳态解的存在条件．     

A CONCEPTUAL MODEL OF A SILTATION SYSTEM IN SHALLOW LAKES WITH LITTORAL VEGETATION

SUMMARY

In shallow lakes a siltation system develops when wind driven water turbulence erodes the lake floor, silt is resuspended and transported by means of waterdrift into the littoral vegetation. Here, due to the resistance of the vegetation, the turbulence is reduced and the silt deposited. Through this mechanism, the prevailing winds have a major rôle in the erosion and siltation pattern, lake morphology, vegetation pattern and in the mixing of water and nutrients from the open water and the reedswamp and vice versa. The model explains the uneven distribution of vegetation at the lakes Neusiedlersee (Austria) and Chilwa (Malawi) satisfactorily, if one assumes a positive correlation between siltation and reedswamp growth and spread.     

氢离子选择性微电极细胞内pH测量系统的研制

本文叙述我们建立的以 IBM PC/XT 兼容机为核心的细胞内 pH 值的测量系统。着重说明对氢离子敏感的离子选择性微电极的制作方法,与其连接的极高输入阻抗的微电极放大器的设计,以及为提高测量的精度而采取的多种措施。阐述了系统的性能、并对其测量精度、优缺点进行了分析与讨论。     

A CETACEAN BIOPSY SYSTEM USING LIGHTWEIGHT PNEUMATIC DARTS, AND ITS EFFECT ON THE BEHAVIOR OF KILLER WHALES

Lightweight untethered pneumatic darts were used to biopsy killer whales, Orcinus orca , for genetic and toxicological analysis. Samples of epidermal, dermal, and hypodermal tissue weighing approximately 0.5 g were obtained by 65% of the 91 darts fired during the study. Sufficient DNA for multiple analyses was extracted from the biopsies, which were also used for fatty acid and toxic contaminant analyses. Reactions such as momentary shakes or accelerations were observed after 81% of the dart hits and 53% of the misses. Aversion to the research vessel was assessed by reapproaching target whales after the sampling attempts. In 6% of the hits and 8% of the misses aversion to the research boat increased immediately following the attempt. No similar increases in aversion were seen when killer whales were reapproached one day to one year after being hit. The darts were also tested successfully on humpback whales, Megaptera novaeangliae . In view of the simplicity of the system, its effectiveness in acquiring multipurpose samples, and the apparently short-term disturbance it caused, it is recommended for future cetacean biopsy studies.     

生态学中一类具时滞反应扩散方程组解的性质

本文讨论一类具时滞反应扩散方程组初边值问题,得到该问题解的存在唯一性并讨论解的渐近性态．     

人巨细胞病毒中枢神经系统先天性感染小鼠模型的电镜研究

目的 应用人巨细胞病毒（ＨＣＭＶ）建立先天性中枢神经系统感染小鼠模型。以电镜研究探讨ＨＣＭＶ先天性感染对中枢神经系统损伤的机制和程度。方法 将ＨＣＭＶ腹腔内中纯系６－８周龄Ｂａｌｂ／ｃ雌雄小鼠成功后给予酱受孕,待雌鼠临产时取出胎鼠脑双侧大脑皮层,进行病毒分离、病理学检验和电镜研究。结果 在鼠脑组织上清液中分离出ＨＣＭＶ;病理学证实,鼠脑为侵袭性脑膜脑炎性病理改变;电镜下研究,在感染组子代鼠脑组织血     

一个高分辨率的凝胶电泳系统及其从蓝藻中分离的叶绿素蛋白复合体

用一高分辨率的凝胶电泳系统从蓝藻类囊体膜中分离出至少１３ 个清晰的叶绿素带,它们是ＣＰＩａ、ＣＰＩｂ、ＣＰＩｃ、ＣＰＩｄ、ＣＰＩｅ、ＣＰＩｆ、ＣＰＩｇ、ＣＰＩｈ、ＣＰａ１、ＣＰａ２、ＣＰａ３、ＣＰａ４ 和ＦＣ,其分辨率较传统方法高出１ 倍多。ＣＰＩａ—ＣＰＩｈ ８ 种组分有相同的吸收光谱,其红峰和蓝峰的位置分别位于６７６ ｎｍ 和４３６ ｎｍ 处。它们都属于光系统Ｉ叶绿素蛋白复合体。ＣＰａ１—ＣＰａ４ ４ 种组分的光谱性质亦基本相同,其吸收峰的位置分别位于６７０—６７２ ｎｍ 和４３６ ｎｍ 处,而低温荧光发射峰的位置都位于６８５ ｎｍ 处。它们都属于光系统Ⅱ叶绿素蛋白复合体     

云南大叶茶体细胞胚发生及体细胞胚苗形成体系的建立

利用云南大叶茶(Camellia sinensis var.assamica Kitamura)胚性细胞系(CL_1)中悬浮培养物,建立了高频率同步化体细胞胚发生及体胚苗形成体系。以改良的MS为基本培养基,将CL_1中培养物由液体保持培养基(0.1mg/L 2,4-D 0.5mg/L 6-BA)继代转入液体诱导培养基(0.05mg/L 2,4-D 0.50mg/L6-BA),暗培养诱导28d,转入不含任何激素的液体分化培养基中再培养28d,获得了不同发育时期的体细胞胚,其发生频率为81.5％。不同发育时期的体细胞胚用不同目的细胞筛收集,在液体生长培养基(1/2 MS 1.0mg/L GA_3 0.5mg/L 6-BA)中培养发育成熟。ABA有利于高质量体细胞胚的形成。20～70月大小的体细胞胚在固体生长培养基中成苗转换率为75％。在液体悬浮培养条件下观察记录了体细胞胚发育过程,证实其过程与合子胚的形态发生过程相似。     

A mathematical model for chronic myelogenous leukemia (CML) and T cell interaction

In this paper, we propose and analyse a mathematical model for chronic myelogenous leukemia (CML), a cancer of the blood. We model the interaction between naive T cells, effector T cells, and CML cancer cells in the body, using a system of ordinary differential equations which gives rates of change of the three cell populations. One of the difficulties in modeling CML is the scarcity of experimental data which can be used to estimate parameters values. To compensate for the resulting uncertainties, we use Latin hypercube sampling (LHS) on large ranges of possible parameter values in our analysis. A major goal of this work is the determination of parameters which play a critical role in remission or clearance of the cancer in the model. Our analysis examines 12 parameters, and identifies two of these, the growth and death rates of CML, as critical to the outcome of the system. Our results indicate that the most promising research avenues for treatments of CML should be those that affect these two significant parameters (CML growth and death rates), while altering the other parameters should have little effect on the outcome.     

THE CONTRIBUTION OF MATING SYSTEM VARIATION TO REPRODUCTIVE ISOLATION IN TWO CLOSELY RELATED CENTAURIUM SPECIES (GENTIANACEAE) WITH A GENERALIZED FLOWER MORPHOLOGY

In closely related plant species that display strong similarities in phenology and pollinator communities, differences in breeding system and associated shifts in floral traits may have important effects on the magnitude and direction of heterospecific pollen flow and hybridization. Here, we quantified the strength of several pre‐ and postzygotic barriers acting between the facultatively outcrossing Centaurium erythraea and the predominantly selfing C. littorale via a suite of experiments, and estimated the frequency of hybridization in the field using molecular markers. The reproductive barriers primarily responsible for preventing hybridization were essentially prezygotic and these acted asymmetrically. Due to differences in floral display, pollen production, and pollen transfer rates, heterospecific pollen flow occurred predominantly from C. erythraea to C. littorale. In C. littorale, on the other hand, close anther–stigma positioning and resulting higher capacity for autonomous selfing functioned as an efficient barrier to counterbalance the higher risk for hybrid mating. In both species the action of all reproductive barriers resulted in a small opportunity for hybrid establishment, which was confirmed by the occurrence of only ～1% putative hybrids in the field. Our findings confirm that differences in breeding system affect heterospecific pollen transfer patterns and that autonomous selfing may efficiently prevent hybridization.     

A PRELIMINARY EVALUATION OF ASPECTS OF SASS (SOUTH AFRICAN SCORING SYSTEM) FOR THE RAPID BIOASSESSMENT OF WATER QUALITY IN RIVERS,WITH PARTICULAR REFERENCE TO THE INCORPORATION OF SASS IN A NATIONAL BIOMONITORING PROGRAMME

Summary

The rapid bioassessment method, SASS (South African Scoring System) has been developed to assess water quality in riverine ecosystems. It is a scoring system based on the presence or absence of macroinvertebrate groups, and yields three values, namely SASS4 Score, Number of Taxa and Average Score Per Taxon (ASPT). The current and future use of SASS, including incorporation into the National Biomonitoring Programme for Riverine Ecosystems, necessitates evaluation of this bioassessment method. This study focuses on three aspects. namely spatial variation in SASS scores, including regional and longitudinal (sub-regional) variation; temporal variation in SASS scores, and the effect of biotope availability on SASS scores.