分子距边矢量与烃类化合物的溶解度及辛醇/水分配系数定量关系的研究

定义并计算了烃类化合物（包括链烃、环烃、芳香烃）的分子距离－边数矢量（μ矢量），藉助多元线性回归技术分别建立了137个烃类化合物的μ矢量与这些物质的正辛醇／水分配系数lgKow及水溶解度的定量结构／性质相关关系模型。模型具有良好的稳定性和预测能力。说明经改进的μ矢量能更好地反映烃类化合物的结构特性。     

La在模拟水生态系统中的动力学行为

采用140La放射示踪技术，研究了稀土元素镧（La）在模拟水生态系统各组分中的迁移分布规律．并建立了相应的数学模型．结果表明，La在模拟水生态系统各组分中的积累率大小依次为：金鱼藻＞底泥＞螺蛳＞鱼，La在系统内的动态变化规律可用封闭分室模型来描述．     

模拟酸雨对红壤铝形态的影响

用动态淋洗试验，研究了不同pH的模拟酸雨对红壤中铝形态和性质的影响．结果表明，酸雨淋洗引起红壤中盐基离子的淋失和土壤铝的溶出．随着酸雨溶液pH的降低，盐基淋矢量和铝溶出量增加．酸雨淋洗影响土壤铝形态的转化，使红壤中交换态铝上升，吸附态羟基铝有所下降．这说明在酸雨长期作用下，羟基铝溶解，并转化为交换态铝和引起铝的溶出，使铝进入环境，危害生态系统．     

沿河城市多点污染排放量优化控制

本文针对沿河城市污染排放的情况,分析了污染物排放对河流造成的污染,并根据Streeter—Phelps模型和城市河流对水质的要求,建立了沿河城市多点污染排放优化控制的线性规划模模,并编制了计算程序用来求解该数学模型.文中提供的算例及计算结果表明,本文提出的沿河城市多点污染排放量优化控制方法对城市排水系统的建设有较大的指导意义.     

亚热带草地资源综合评价的数学模型

本文在前人工作的基础上,对亚热带草地资源评定因素进行了筛选与合理组合,编排了各评定因素的多层次评判顺序,组建了综合评价草地资源的模糊数学模型。首次应用数学模型对我国亚热带草地资源进行了综合评价。为验证该数学模型的灵敏度,笔者列举了我国南方四个草地类型,作了具体计算。结果表明,数学模型本身具有较高的灵敏度,完全可以用于评价我国南方天然草地资源。     

我国污水处理的发展趋势

目前我国污水处理的总体发展趋势；一是普及城市污水处理，二是提高工业废水排放达标率，三是推广污水回用。论文重点介绍了城市污水的强化一级处理、数学模型用于精确控制的技术，清洁生产在提高工业废水排放达标方面的作用，以及再生水作为环境用水的回用方式。     

QuickPanel在油浆过滤自动控制系统中的应用研究

阐述了油浆过滤控制系统的硬件配置、分程控制及顺序控制等．通过控制系统的控制,过滤器A、B轮流进行过滤、再生步骤,将油品内51μm以上的颗粒过滤掉,达到提高油品质量、延迟装置检维修期的目标．图1,参5．     

南亚热带丘陵土壤水分循环及其有效性的研究──Ⅷ.丘陵赤红壤水分循环与平衡数学模型

依据田间实测资料，在分析丘陵赤红壤水分性质的基础上，建立了土壤有效含水量与土壤物理粘粒含量之间的数学模型、土壤水分特征曲线数学模型、土壤月均贮水量与月降雨总量之间的数学模型和径流率与土壤表层初始含水量之间的数学模型，研究了土壤水分循环与平衡数学模型及各分量与参数的确定方法.     

铁盐和铝盐混凝剂对消毒副产物的控制作用及机制研究

以三氯化铁和硫酸铝为研究对象,探讨了两种混凝剂对三氯甲烷生成量的控制作用及控制机制．结果表明,与硫酸铝相比,三氯化铁可以更好地控制三氯甲烷的生成量,对有机物的去除方面,也具有良好的效果．E4／E6变化表明,三氯化铁和硫酸铝对水中有机物的去除机制不同,硫酸铝主要去除水中大分子的有机物,三氯化铁更倾向于去除水中小分子有机物,而这些小分子有机物通常是消毒副产物的前体物,从而使三氯化铁对消毒副产物的控制作用较硫酸铝明显．     

沉积物中多环芳烃和有机氯农药定量分析的质量保证和质量控制

以美国ＥＰＡ为方法为基础,进行了沉积物中多环芳烃和有机氯农药分析的质量保证和质量控制实验,采用回收率指示物控制回收率,用内标法定量。结果表明多环芳烃的指示物回收率为５０．６７－９７．３３％,目标化合物的回收率为５８．６７－９６．３３％,方法检测限为３．３０－９．２６μｇ．ｋｇ＾－１。     

Parental favouritism strategies in the asynchronously hatching European Roller (<Emphasis Type="BoldItalic">Coracias garrulus</Emphasis>)

In altricial birds, resource allocation during early developmental stages is the result of an interaction between parental feeding decisions and scramble competition between nestmates. Hatching asynchrony in birds leads to a pronounced age hierarchy among their offspring. Therefore, whenever parents exert control over resource allocation parents feeding asynchronous broods should simultaneously assess individual offspring internal condition and age. In this study, we first studied whether the highly ultraviolet (UV) reflective body skin of nestlings in the asynchronous European Roller (Coracias garrulus; roller hereafter) relates to nestling quality. In a second stage, we experimentally studied parental biases in food allocation towards senior and junior sibling rollers in relation to a manipulation of UV reflectance of the skin of their offspring. Heavier roller nestlings had less brilliant and less UV saturated skins than weaker nestlings. In our experiment, we found that parents with large broods preferentially fed nestlings presenting skin coloration revealing small body size (i.e. control nestlings) over nestlings presenting skin coloration revealing large body size (i.e. UV-blocked nestlings). Within the brood, we found that parental food allocation strategy depended on nestling age: parents preferentially fed senior nestlings signalling small body size, but did not show preference between control and UV-blocked junior nestlings. These results emphasise that parent rollers use UV cues of offspring quality while balancing the age of their offspring to adjust their feeding strategies, and suggest that parents may adopt finely tuned strategies of control over resource allocation in asynchronous broods.     

Using the maximum principle of impulse control for ecology-economical models

In this work we present mathematical models for population of single cohort and homogeneous animals. Investigating these mathematical models, we determine structure of optimal impulsive control which used maximum principle for optimal processes with impulse control.     

The function of hatching asynchrony in the blue-footed booby

The blue-footed booby (Sula nebouxii) commonly hatches two eggs 4 days apart; then the senior (first-hatched) chick aggressively dominates the other and sometimes kills it. Two hypotheses explaining the function of the hatching interval were tested by creating broods with synchronous hatching: the facultative brood reduction hypothesis of Lack (1954) and the sibling rivalry reduction hypothesis of Hahn (1981). The results contradicted most predictions of both hypotheses: synchronous broods formed an aggressive hierarchy similarly to asynchronous broods (controls), and subordinate chicks grew poorly (Fig. 1) and died frequently, similarly to junior chicks in control broods. However, compared with synchronous broods, asynchronous broods showed less aggression (Fig. 2), diminished food allocation to subordinate chicks (Fig. 3) and less total food consumption (30% fewer feeds at age 0–10 days). These behavioral comparisons took into account the different ages of chicks in different treatments. The results suggest that natural asynchrony makes brood reduction more efficient and decreases the costs of sibling aggression to parents, in terms of their future survival or fecundity, as proposed by Mock and Ploger (1987). Further, in exaggeratedly asynchronous broods (8-day hatch interval) junior chicks suffered more aggression (Fig. 4) and grew more slowly than junior chicks in control broods. This result supports the hypothesis of optimal hatch asynchrony of Mock and Ploger (1987).     

Is asynchronous hatching adaptive in herring gulls (Larus argentatus)?

Hatching asynchrony commonly induces a size hierarchy among siblings and the resultant competition for food between siblings can often lead to starvation of the smallest chicks within a brood. We created herring gull (Larus argentatus) broods with varying degrees of hatching synchrony by manipulating the timing of incubation while maintaining the originally laid eggs. The degree of hatching asynchrony affected sibling size hierarchy at the time of hatching of the last-hatched ”c-chick.” In unmanipulated broods, there was no disadvantage of being a c-chick. However, when asynchrony was experimentally increased, we found reduced survival of the c-chick only in the exaggerated asynchronous experimental group. The effects were observable only during the first 10 days of chick life. We recorded no cases of the chicks dying of starvation. Furthermore, behavioral observations indicated that there was no sibling competition, and no selective feeding of larger sibs in the study colony. We propose that the observed lower survival rates of c-chicks in exaggerated asynchronous broods resulted from their lesser motor abilities, affecting their chances of escaping predators. Fledging success for the whole colony was generally high and almost half of all pairs fledged all three chicks, which is indicative of a good feeding environment. We argue that normal hatching asynchrony is a favorable solution in a good feeding environment, but that increased asynchrony reduces breeding success. We do not view asynchrony in the herring gull as an adaptation for brood reduction and propose instead that it may come about because there has been selection for incubation to start before clutch completion. Received: 14 April 1999 / Received in revised form: 20 October 1999 / Accepted: 23 January 2000     

Maternal effects on begging behaviour: an experimental demonstration of the effects of laying sequence, hatch order, nestling sex and brood size

Differential resource allocation by females across the laying sequence has been hypothesised as a mechanism through which females could either compensate nestlings that hatch last in asynchronous broods or promote brood reduction. In this study we artificially incubated eggs and cross-fostered offspring to manipulate nestlings’ position in the hatching order, to identify whether the competitive ability of nestlings is dependent on position in the laying sequence. In both control and experimentally reversed broods, first hatched chicks had a higher survival than last hatched siblings. Yet, nestlings that hatched from eggs laid in the second half of a clutch begged with a greater intensity than nestlings hatched from eggs laid in the first half of a clutch. In natural broods, the greater begging competitiveness of nestlings from later-laid eggs led to a moderation of sibling competition and these nestlings achieved the same body size and weight as nestlings from eggs laid in the first half of the clutch. The lack of a substantial difference in the size and condition of surviving nestlings in respect to laying order suggests that differential resource allocation across the egg-laying sequence partially compensates for hatching last in asynchronous broods and reduces the negative effects of the nestling size hierarchy. The effect of laying order, brood size and experimental treatment also differed for male and female nestlings. Our study highlights the need to be aware of the complex and subtle effects of nestling sex and laying sequence when investigating genetic and environmental influences on individual fitness.     

Invasion with stage-structured coupled map lattices: Application to the spread of scentless chamomile

Two fundamental aspects of invasion dynamics are population growth and population spread. These quantities have been subject of study in biological invasions and can be used to study management and control of organisms. In this paper we derive formulae to calculate wave speed and rates of spread for coupled map lattices. Coupled map lattice models are dynamical models where space and time are discrete. We also show how wave speed and rate of spread can be calculated for structured population coupled map lattices in deterministic, stochastic environments and heterogeneous landscapes. Coupled map lattices are simple mathematical models that can be easily linked to landscape data to study invading organisms control strategies.     

Food-dependent benefits of hatching asynchrony in American kestrels Falco sparverius

Food supply and hatching asynchrony were manipulated for 90 broods of American kestrels (Falco sparverius) during 1989–1991. We measured the growth and mortality of nestlings within four treatment groups (asynchronous, synchronous, food-supplemented, unsupplemented) to test the brood reduction hypothesis of Lack (1947, 1954). Fledging success did not differ between synchronous and asynchronous broods when food was poor but consistent with the brood reduction hypothesis, nestlings died at a younger age in asynchronous broods. When food was supplemented, mortality did not occur in the synchronous broods but youngest nestlings still died in asynchronous nests despite apparently adequate food for the brood. Oldest nestlings in asynchronous broods fledged with a greater mass than their younger siblings, also consistent with Lack's hypothesis. Average nestling quality in synchronous broods was very dependent on food levels. Synchronous young that were supplemented were, on average, the heaviest of any treatment group but young from unsupplemented synchronous broods were the lightest. Overall, patterns of mortality and growth for kestrels support the brood reduction hypothesis when food is limited, but not when it is abundant. This food-dependent benefit of asynchrony in the nestling period is a prerequisite for facultatively adjusted hatching spans during laying.     

Sibling aggression, hatching asynchrony, and nestling mortality in the black kite (Milvus migrans)

In siblicidal species, hatching asynchrony could act to reduce sibling rivalry or promote the death of last-hatched chicks. The pattern of hatching asynchrony was experimentally altered in the black kite Milvus migrans. Hatching asynchrony in control broods was intermediate between those of experimentally synchronised and asynchronised broods. Sibling aggression and wounds on the chicks were more commonly observed early in the nestling period and in synchronous nests. Serious injuries were observed on last-hatched chicks in asynchronous nests, as were observations of intimidated or crushed chicks. Sibling aggression was related to food abundance, but some chicks died at an early age in nests with abundant food (cainism). Cainism was more commonly found in asynchronous nests. For species with facultative siblicide, moderate hatching asynchrony could be a compromise between reducing sibling rivalry and avoiding large size differences between sibs that would result in cainism. Female black kites preferentially fed the smallest chicks and exhibited behaviours to reduce sibling aggression, contrary to observations in other siblicidal species. In a highly opportunistic forager such as the black kite, a strategy may exist to protract the life of all the chicks in the brood, waiting for unpredictable situations of food overabundance. This would induce the appearance of a parent-offspring conflict over brood reduction, reflected in the existence of a possible anticipated response by some of the chicks (cainism) and in the appearance of special behaviours by the parents to selectively feed smaller chicks or reduce sibling aggression. In this facultatively siblicidal species, cainism does not seem to be the final stage of an evolutionary trend favouring the raising of high-quality chicks, but a manifestation of a parent-offspring conflict over brood size. Received: 9 March 1998 / Accepted after revision: 8 August 1998     

Assessment of spatial distribution of submerged vegetation in the Orbetello lagoon by means of a mathematical model

Coastal lagoons are characterized by a constant threat of eutrophication and a critical coexistence of differing submerged vegetation forms. This paper investigates the competitive equilibrium of macroalgae and phanerogams in the Orbetello lagoon in relation to physico-chemical and environmental factors, including wind, nutrients in the water column, and sediment characteristics. A mathematical model describing the evolution of the submerged vegetation as a function of the abiotic parameters is used here in conjunction with specific experimental studies to explain the relationship between phanerogams (seagrasses) prairie expansion, water movements, and sediment characteristics. The combination of specific sediment sampling and mathematical modelling shows that water circulation and the state of the upper sediment are both dominant factors in determining the phanerogams distribution in the lagoon and the mutually exclusive growth of these groups in differing parts of the lagoon. Water currents control the distribution of floating macroalgae, resulting in an uneven accumulation of decomposing biomass and phanerogams seed dispersal. The oxygenation provided by the rooted phanerogams affects the sediment characteristics, making them suitable for further prairie expansion. In addition to sediment analysis the use of a mathematical model combining the hydrodynamics and the water quality of the lagoon provides a thorough explanation of the expansion of the rooted vegetation in critical areas. A further result of this research is the validation of the model, originally calibrated with the lagoon central stations’ data, with the newly acquired data from several other parts of the ecosystem. The model predictions are in good agreement with the field observations under a number of environmental conditions and explain the observed expansion trend of phanerogams, which are beneficial for the lagoon ecology, more thoroughly than by relying on the sediment observations alone.     

An economic assessment of air pollution damages to selected annual crops in Southern California

Agricultural production is influenced by many factors beyond the control of individual producers. In recent decades, air pollution has become one of these exogenous factors. This study uses a price-endogenous mathematical programming model to assess the economic benefits of reducing 1976 ambient oxidant exposures of 14 annual crops in southern California. A measure of the distributional consequences of these benefits across producers, consumers and locations is also provided. Results indicate that 1976 benefits of control for the fourteen included crops would have been approximately $46 million.