一类扩散的种内相食系统正平衡态的全局渐近稳定性

讨论一类扩散的种内相食的捕食者-食饵模型,该模型带有齐次Neumann边界条件.通过迭代的方法证明:在适当的条件下,该模型唯一正常数平衡解全局渐近稳定.     

一类传染病模型的扩散性质

讨论了扩散对传染病模型的阈值的影响、扩散对传染病模型中染病者人数的影响以及扩散对传染病模型的平衡点的几何性质的影响．     

若干具有非线性传染力的传染病模型的稳定性分析

讨论了具有常数迁入和非线性传染力的三类传染病模型,即SIRI模型,SIRI框架下的DS模型及SIR框架下的DI模型。给出了它们基本再生数R0的表达式,证明了R0≤1时无病平衡点是全局稳定的,同时证明了如果地方病平衡点存在,则必是全局稳定的结果（从而必唯一）对第一和第三个模型还给出了R0＞1时地方病平衡点的存在唯一性。     

具有扩散和群体防卫的简单食物链模型的动力性态

本文研究一类具有扩散和群体防卫的简单食物链的确定模型,我们用Ｇａｌｅｒｋｉｎ方法证明了问题整体解的存在唯一性,进而证明了方程所生成的算子半群拥有整体吸引子。     

一类S-I传染病模型行波解的存在性

本文研究了一类具有扩散且是非线性传染率的SI传染病模型,分析了模型的行波解的存在性条件,给出了最小波速与产生单调和振荡行波解的条件,并且进行了计算机仿真．     

一类带有隔离项和分布时滞的SIQS模型的稳定性分析

研究了一类带有隔离项和分布时滞的SIQS模型,利用局部线性化方法并构造了适当的Liapunov函数,获得了该系统平衡点的稳定性结论.     

具有竞争和阶段结构的Lotka-Volterra扩散模型稳定性分析（英文）

研究一类具有竞争和阶段结构Lotka-Volterra扩散模型,并由线性化方法和Lyapunov函数方法给出了该模型正平衡点局部和全局渐近稳定的条件.     

基于GARP的三种芒果象甲在中国的适生性分析

芒果象甲Sternochetus Pierce昆虫是芒果的重要害虫,明确其可能适牛的区域对该虫的科学监测及防治意义重大.本文利用芒果象甲属中主要3种:印度果核芒果象S.mangiferae Fabricius、果核芒果象S.olivieri Faust、果肉芒果象S.frigidus Fabrieius的已知分布点数据和亚洲地区的14个环境地理变量图层,运用GARP生态位模型结合GIS空间分析模块预测了该虫在中国的潜在地理分布,结果表明芒果象甲具有较强的扩散蔓延趋势,对我国的芒果产业构成较大的潜在威胁.     

关于膜蛋白侧向限制扩散的讨论

讨论了膜骨架栅栏模型和系链模型解释膜蛋白侧向限制扩散时的困难。在蛋白质一维约束扩散实验现象的基础上,提出了膜蛋白的两维约束扩散模型,并用这个模型讨论了膜蛋白的多种运动模式。     

具脉冲收获与脉冲单边扩散的单种群动力学模型研究

建立了一类具脉冲收获与脉冲单边扩散在不同固定脉冲时刻的单种群动力学模型利用离散动力系统频闪映射理论,得到了脉冲收获的阈值.该结论说明只要收获量不超过其阈值通过扩散则种群可以保持持续生存.     

矿区生态产业共生系统的稳定性

以矿区生态产业共生系统为研究对象,重点研究了影响其稳定性的因素。从矿区生态产业共生系统的共生模式及其共生策略两方面对系统稳定性进行了深入探讨。利用Logistic模型分析共生模式对系统稳定性的影响;利用博弈论分析共生策略对系统稳定性的影响。在此基础上,提出了相应的解决方案,从而有助于解决矿区生态产业共生系统的稳定性问题。     

稳定性视角下黄土高原生态系统与生计系统的冲突与耦合——以陕西省佳县为例

黄土高原地区是我国生态脆弱和深度贫困的高度耦合区,长期面临生态治理和生计保障的双重压力,如何协调乡村生态系统与农户生计系统之间的平衡成为区域人地系统稳定和可持续发展的关键。基于稳定性概念内涵,以黄土高原佳县为例,采用地理空间数据和问卷调查数据,定量评价生态系统和生计系统现状,利用耦合协调度和相对发展度模型,梳理两个系统之间的相互作用关系并划分冲突与耦合类型区,在此基础上分析冲突关系的成因并提出分类治理建议,以期为区域人地矛盾缓解和可持续治理提供参考。结果表明：(1)佳县生态系统稳定性整体较高,但空间分异特征明显。县域生态稳定性格局呈“北部低值成片,南部低值分散”的特征,以道路交通用地和建设用地为表征的人为因素对生态稳定性的影响显著;(2)佳县生计系统稳定性整体处于中等级,农户生计方式已趋于多元,但生计资本仍较为匮乏。多样化的生计在一定程度上能够弥补生计资本的欠缺,而地理区位和自然条件对生计系统稳定性的维持作用仍不容忽视;(3)佳县生态系统与生计系统的相互关系以冲突为主,中度冲突、轻度冲突、濒临冲突和勉强平衡四种类型同时存在,勉强平衡区属于生态系统和生计系统稳定性双低的假性平衡,人地矛盾...     

金融稳定性与生态稳定性

亚洲金融危机以后,世界各国评估和诊断金融体系稳健程度的实务性研究取得了很大进展,但金融稳定性问题的理论研究仍相对滞后.本文讨论了用生态稳定性思想方法研究金融稳定性问题.文章先比较了金融稳定性的概念和生态学中有关稳定性的概念的异同,把生态稳定性概念移植、引申到金融系统中,建立了金融群落数学模型,给出了金融群落金融稳定的定义,论证了金融种群确定模型和随机模型的稳定性,介绍了金融群落随机模型的稳定性,最后分析了金融群落等级结构的稳定性.     

The Linnaean system and its 250-year persistence

The Linnaean system of nomenclature has been used and adapted by biologists over a period of almost 250 years. Under the current system of codes, it is now applied to more than 2 million species of organisms. Inherent in the Linnaean system is the indication of hierarchical relationships. The Linnaean system has been justified primarily on the basis of stability. Stability can be assessed on at least two grounds: the absolute stability of names, irrespective of taxonomic concept; and the stability of names under changing concepts. Recent arguments have invoked conformity to phylogenetic methods as the primary basis for choice of nomenclatural systems, but even here stability of names as they relate to monophyletic groups is stated as the ultimate objective. The idea of absolute stability as the primary justification for nomenclatural methods was wrong from the start. The reasons are several. First, taxa are concepts, no matter the frequency of assertions to the contrary; as such, they are subject to change at all levels and always will be, with the consequence that to some degree the names we use to refer to them will also be subject to change. Second, even if the true nature of all taxa could be agreed upon, the goal would require that we discover them all and correctly recognize them for what they are. Much of biology is far from that goal at the species level and even further for supraspecific taxa. Nomenclature serves as a tool for biology. Absolute stability of taxonomic concepts—and nomenclature—would hinder scientific progress rather than promote it. It can been demonstrated that the scientific goals of systematists are far from achieved. Thus, the goal of absolute nomenclatural stability is illusory and misguided. The primary strength of the Linnaean system is its ability to portray hierarchical relationships; stability is secondary. No single system of nomenclature can ever possess all desirable attributes: i.e., convey information on hierarchical relationships, provide absolute stability in the names portraying those relationships, and provide simplicity and continuity in communicating the identities of the taxa and their relationships. Aside from myriad practical problems involved in its implementation, it must be concluded that “phylogenetic nomenclature” would not provide a more stable and effective system for communicating information on biological classifications than does the Linnaean system.     

湖滨湿地生态系统稳定性评价

根据生态系统稳定性的产生原因,将稳定性划分为系统整体稳定性和系统结构稳定性。从系统的稳定性出发,以生态系统的整体稳定性和结构稳定性两个方面为对象,对湖滨湿地生态恢复所产生的生态效益进行了研究。针对系统整体稳定性,给出了生物多样性指数、自然保护区比重和自然灾害等级3个评价指标,并介绍了相应的指标量化方法。与此同时结合能值理论,准确地分析了湖滨湿地生态系统的结构稳定性,为评价湖滨湿地生态恢复的生态效益评价提供了客观的标尺。     

A model of neuro-musculo-skeletal system for human locomotion under position constraint condition

The human locomotion was studied on the basis of the interaction of the musculo-skeletal system, the neural system and the environment. A mathematical model of human locomotion under position constraint condition was established. Besides the neural rhythm generator, the posture controller and the sensory system, the environment feedback controller and the stability controller were taken into account in the model. The environment feedback controller was proposed for two purposes, obstacle avoidance and target position control of the swing foot. The stability controller was proposed to imitate the self-balancing ability of a human body and improve the stability of the model. In the stability controller, the ankle torque was used to control the velocity of the body gravity center. A prediction control algorithm was applied to calculate the torque magnitude of the stability controller. As an example, human stairs climbing movement was simulated and the results were given. The simulation result proved that the mathematical modeling of the task was successful.     

Stability analysis of a continuum-based constrained mixture model for vascular growth and remodeling

A stabilizing criterion is derived for equations governing vascular growth and remodeling. We start from the integral state equations of the continuum-based constrained mixture theory of vascular growth and remodeling and obtain a system of time-delayed differential equations describing vascular growth. By employing an exponential form of the constituent survival function, the delayed differential equations can be reduced to a nonlinear ODE system. We demonstrate the degeneracy of the linearized system about the homeostatic state, which is a fundamental cause of the neutral stability observations reported in prior studies. Due to this degeneracy, stability conclusions for the original nonlinear system cannot be directly inferred. To resolve this problem, a sub-system is constructed by recognizing a linear relation between two states. Subsequently, Lyapunov’s indirect method is used to connect stability properties between the linearized system and the original nonlinear system, to rigorously establish the neutral stability properties of the original system. In particular, this analysis leads to a stability criterion for vascular expansion in terms of growth and remodeling kinetic parameters, geometric quantities and material properties. Numerical simulations were conducted to evaluate the theoretical stability criterion under broader conditions, as well as study the influence of key parameters and physical factors on growth properties. The theoretical results are also compared with prior numerical and experimental findings in the literature.     

Characterization of the stability of recombinant protein production in the GS-NS0 expression system

The GS-NS0 system is an important mammalian expression system used largely within industry for the high-level expression of recombinant proteins for therapeutic use. It is essential that the productivity of this system remains stable throughout culture expansion for the successful long-term production of recombinant proteins. Here we present a study of the stability of recombinant protein production from unamplified GS-NS0 cell lines over extended period of continuous culture. The cell lines used in this study were generated by the transfection of NS0 cells with DNA encoding for a secreted recombinant protein and by two subsequent rounds of limiting dilution cloning prior to analysis of stability. The stability of recombinant protein production was assessed at intervals over a period of 134 days using repeated batch culture in shake flasks. Heterogeneous stability was identified. The productivity of some clones remained consistent throughout 134 days of continuous culture. Others exhibit rapid and progressive loss of productivity. Analysis of the causal relationships underlying stability indicates that the initial transfectant determines the susceptibility to loss or retention of productivity. Selection of production clones on the basis of growth and productivity alone will not predict stability during long-term culture. Our research indicates that stable high-producing clones can readily be obtained from use of the GS-NS0 system in the absence of amplification but there may be molecular features of the original transfectants that could serve as very important predictive indicators of the stability of recombinant protein production.     

Relative efficiency of abdominal muscles in spine stability

Using an iterative kinematics-driven nonlinear finite element model, relative efficiency of individual abdominal muscles in spinal stability in upright standing posture was investigated. Effect of load height on stability and muscle activities was also computed under different coactivity levels in abdominal muscles. The internal oblique was the most efficient muscle (compared with the external oblique and rectus abdominus) in providing stability while generating smaller spinal loads with lower fatigue rate of muscles. As the weight was held higher, stability deteriorated requiring additional flexor-extensor activities. The stabilising efficacy of abdominal muscles diminished at higher activities. The difference in critical loads in frontal and sagittal planes computed in the absence of abdominal coactivity disappeared under prescribed coactivities suggesting an optimal system in stability. The central nervous system may settle for a less stable spine in favour of lowering the risk of injury. Findings could help introduce stability criterion in optimisation models.