Fluctuating Asymmetry in Cranial Measurements of East European Voles (Microtus rossiaemeridionalis Ognev, 1924) from the Zone of Radioactive Contamination

Fluctuating asymmetry (FA) in eight cranial measurements was studied in Microtus rossiaemeridionalis voles from two sites of the zone affected by the Totsk Radioactive Trace (TRT) and in the control population. In the affected populations, generalized mean population parameters of FA were significantly higher than in the control and tended to increase in relatively larger animals. The disturbance of ontogenetic homeostasis in voles from the TRT zone probably resulted from environmental stress caused by contamination with radionuclides (primarily plutonium), which entailed irradiation of many vole generations over more than 40 years.     

Phenogenetic monitoring of the weeping birch (<Emphasis Type="Italic">Betula pendula</Emphasis> Roth.) in the Middle Urals: testing a new method for assessing developmental instability in higher plants

Variation of bilateral leaf structures in Middle Ural cenopopulations of the weeping birch (Betula pendula Roth.) growing in gradients of industrial pollution was studied to test the efficiency of a new method of population and individual phenogenetic monitoring allowing an indirect assessment of developmental destabilization by segregating the variance of total asymmetry (TA _R ²) into its additive components, the variances of fluctuating asymmetry (FA _R ²) and directional asymmetry (DA _R ²). The method was tested in the impact zones of two copper-smelting plants in the Middle Urals. The degree of impact was characterized by the index of technogenic pollution (ITP) reflecting the average total contents of 15 water-soluble pollutants in snow samples. The level of asymmetry was estimated from the numbers of denticles with incoming veins (dentovenal elements) on the left and right leaf margins. Spearman’s coefficient of rank correlation between the group values of variance in fluctuating asymmetry (FA _R ²) and corresponding ITP values reached r _S = 0.914 (p < 0.001), providing evidence that the method is highly appropriate for ecological indication of the phenogenetic response of trees to environmental pollution.     

基于数字锁相技术的飞机货舱火灾烟雾光学参数方法研究*

为解决飞机货舱火灾光学探测易受环境杂光和空气中灰尘、水汽干扰,误报率高的问题,提出1种基于数字锁相的双波长火灾烟雾探测方法。利用数字锁相技术调制双波长光源,选择性地提取微弱光散射信号,并设计前、后双向散射光探测光路。采用常见火灾材料及干扰源进行真假火源实验,依据米氏散射理论及不同粒径气溶胶颗粒对不同波长光的散射效应差异,以不对称比（AR）和双波长光强比（DWIR）作为火灾检测参数对不同粒径颗粒进行区分,根据2种火灾检测参数建立数据样本,利用BP神经网络进行分析,并加入复合式传感器实验作为对比。研究结果表明:基于数字锁相技术的火灾烟雾光学探测方法能够在一定程度上区分火灾烟雾和干扰源,误报率小于3.5%。     

新疆伊犁州2次6级地震加速度记录特征对比分析

分析了伊犁州2次6级地震地震动峰值不对称比、持时、峰值衰减特征和规律,选取5个典型台站的加速度记录,其中2个台站获得了较大加速度峰值,仪器烈度达VIII度,另外3个台站在2次地震中都获取记录,一个位于伊犁河谷、一个位于北天山山前、一个位于南天山山前,分别进行了地震动反应谱和傅氏谱比特征的对比分析。通过对2次地震强震动记录特征研究,探讨新疆伊犁州地区中强地震的强震动特征。     

地震动特征的统计分析

统计了国内外287次5级以上的实际地震记录,研究了地震动峰值不对称比、持时、地震荷载类型的统计特征和规律。结果表明：地震动峰值具有明显的不对称性,可以用峰值不对称比描述,统计结果具有规律性,其平均值总体上随震级加大而略有降低,从5级到8级地震其范围变化为1.4～1.2;地震动持时随震级增大而增大,近似于线性增长,震级从...     

The role of size inequality in self-thinning: A pattern-oriented simulation model for arid savannas

The self-thinning line is a very robust pattern, which can be obtained in modeling studies by a variety of different mechanistic assumptions. Our opinion is that we can only advance in our understanding of mechanisms leading to the self-thinning relationship if we demand that the model also reproduces several other characteristic features (patterns) of the self-thinning process such as the degree of size inequality and the average size. We use a pattern-oriented modeling approach to develop a model of self-thinning under size inequality in overcrowded, even-aged stands, which reproduces these three patterns simultaneously. Our approach is to first develop an initial model based on our current ecological knowledge and then to refine the model by modifying the initial model to derive the model that reproduces all patterns of interest.The initial model is as simple as possible while avoiding incidental, ecologically unjustified, assumptions. It is a further development of zone of influence-simulation models: each plant is described by two circles, one describing a minimum-domain-area and one describing the zone of influence. In the initial model, mortality is “death-by-contact” of minimum-domain-areas and growth is a function of inter-tree competition, i.e. overlapping zones of influence. Model parameterization is based on field data on Acacia reficiens in southern Africa. Simulations follow patches of initially small trees through time for up to 1000 years with five parameters, three describing growth and two describing inter-tree competition. A sensitivity analysis shows that all parameters of the initial model contribute significantly to the number and size of plants through time. The two competition parameters, which describe competitive asymmetry and the size of the zone of influence relative to canopy size, are both important for generating size inequality. Thus, both competitive asymmetry and spatial pattern contribute to size inequality, and their relative importance may vary greatly.The sensitivity analysis suggests that all processes included in the initial model are essential to the evolution of size inequality. However, size inequality under the initial model is below field values, meaning that additional, as yet unconsidered processes, contribute to size inequality. Our best-fit model additionally contains details on growth stochasticity.This study establishes the often-proposed direct link between mortality driven by local competition and self-thinning and highlights the importance of stochasticity in ecological processes.     

Habitat preference increases territorial defence in brown trout (Salmo trutta)

The striking ability of territory owners to repel intruders has generated a number of theoretical explanations as well as experimental studies in many animal species. However, effects of individual habitat preferences on territorial defence have rarely been studied. From the territory value hypothesis, we predicted that owners of preferred habitats should invest more resources in defence than owners of non-preferred habitats. We tested this prediction with young territorial brown trout in a two-stage experiment. First, trout were allowed to choose individually between gravel and a uniform bright substrate. As expected, they showed a significant (79%) preference for gravel. However, there was considerable variation between individuals in substrate preference, with a few fish preferring the bright substrate. Half of the tested fish were then transferred to a gravel substrate and the rest to a bright substrate, manipulating habitat type in relation to preference. Territory owners were then staged against size-matched intruders whereupon contest aggression was observed and the winner of each contest determined. Overall, owners won most of the contests. Satisfied owners won 86% and owners of less preferred territories, 74% of the contests. Furthermore, more satisfied owners attacked sooner and were more aggressive relative to the intruders. We conclude that brown trout show individual variation in habitat preference, which appears to be linked with their investment in territorial defence. These results suggest that understanding and modelling of animal contests could benefit from considering how territorial defence is influenced by individual habitat preference and specialisation. Received: 25 February 2000 / Revised: 22 May 2000 / Accepted: 25 June 2000     

旅游市场信息不对称的状况及对策研究

旅游市场信息不对称现象具有特定的表现形式,它不仅造成了旅游市场的不正当竞争,而且对旅游者权益造成了极大的危害。改善旅游市场信息不对称现象,是规范旅游市场、维护良好市场秩序、促进旅游业健康发展的保证。从市场信息不对称的状况入手,立足于对旅游地、旅行社和旅游者三方信息不对称的客观现实,分析了信息不对称的表现形式及其危害,重点研究了如何改善旅游市场信息不对称现象。     

Patterns of fluctuating asymmetry in beetle horns: an experimental examination of the honest signalling hypothesis

Recent theoretical arguments have claimed that negative relationships between the size and symmetry of secondary sexual traits are indicative of honest signalling of male quality. The patterns of fluctuating asymmetry in beetle horns have been proposed to support the honest signalling hypothesis. Here we examine three assumptions of the hypothesis, (1) that traits are costly to produce; (2) the levels of fluctuating asymmetry are indicative of stress imposed during development; and (3) that males with larger traits should have more symmetrical traits, using the horned beetle, Onthophagus taurus. Experimental manipulations of brood mass were used to manipulate horn size and asymmetry. The development of horns was found to be environmentally determined and costly in terms of delayed development and increased risk of pre-adult mortality. Decreasing resource availability increased relative horn asymmetry. However, horn height was positively related to absolute horn asymmetry. While the results do support the hypothesis that sexual selection on secondary sexual traits should increase levels of fluctuating asymmetry, they provide no support for the notion that the patterns of asymmetry honestly signal male quality. Horns are used in disputes between males and may be indicative of male parental investment. Thus, we conclude that while horn size may be an indication of male quality, the patterns of fluctuating asymmetry are not. Received: 16 December 1996 / Accepted after revision: 5 May 1997