变系数变时滞BAM神经网络概周期解的存在性与全局吸引性

利用指数二分性、Banach不动点定理与微分不等式分析技巧,在不要求激活函数有界的条件下,给出了变系数变时滞的BAM神经网络概周期解的存在唯一性和全局吸引性的充分条件．所得结果推广和改进了相应文献的结果。对设计BAM神经网络概周期振荡有重要意义．     

具有一般形式饱和接触率SEIS模型渐近分析

研究具有一般形式饱和接触率SEIS模型渐近性态,得到决定疾病绝灭和持续的阈值-基本再生数R0。当R0 ≤ 1时,仅存在无病平衡点P^0;当R0＞1时,除存在无病平衡点P^0外,还存在惟一的地方病平衡点P^＊。当R0＜1时,无病平衡点P^0全局渐近稳定;当R0＞1时,地方病平衡点P^＊局部渐近稳定。特别地,无因病死亡时,极限方程地方病平衡点P^-＊全局渐近稳定。     

Relationship between ovarian cycle phase and sexual behavior in female Japanese macaques (Macaca fuscata)

We conducted behavioral observations simultaneously with fecal sample collection on eight nonlactating females 2-3 times per week, October 1997-March 1998, to examine the relationship between ovarian hormones and the sexual behavior of female Japanese macaques (Macaca fuscata) during the mating season. We analyzed samples by enzyme immunoassay for fecal hormone levels. Hormone profiles of estrone-glucuronide (E1) and pregnanediol-glucuronide (PdG) were used to separate ovarian cycles into three phases (follicular, periovulatory, and luteal). Hormonal profiles indicate average cycle lengths of 27.6 +/- 4.2 days (+/- SD; n = 26). Average lengths of the luteal and follicular phases were 12.3 +/- 3.8 days (+/- SD) and 8.3 +/- 3.4 days (+/- SD), respectively. We observed female Japanese macaques engaging in sexual activity throughout the ovarian cycle, with the highest rates occurring during the follicular and periovulatory phases as compared to the luteal phase. The attractivity of female Japanese macaques increased significantly during the follicular and periovulatory phases of the ovarian cycle, when E1 levels are peaking and PdG levels drop to baseline. In addition, females displayed a significant increase in proceptive behavior during the follicular and periovulatory phases. Grooming bouts, as well as proximity between female and male macaques, also increased significantly during the follicular and periovulatory phases. We conclude that fluctuating levels of ovarian hormones in different phases of the cycle are significantly associated with variable rates of copulatory and pericopulatory behaviors in these Japanese macaque females.     

Evolution of honest reward signal in flowers

Some flowering plants signal the abundance of their rewards by changing their flower colour, scent or other floral traits as rewards are depleted. These floral trait changes can be regarded as honest signals of reward states for pollinators. Previous studies have hypothesized that these signals are used to maintain plant-level attractiveness to pollinators, but the evolutionary conditions leading to the development of honest signals have not been well investigated from a theoretical basis. We examined conditions leading to the evolution of honest reward signals in flowers by applying a theoretical model that included pollinator response and signal accuracy. We assumed that pollinators learn floral traits and plant locations in association with reward states and use this information to decide which flowers to visit. While manipulating the level of associative learning, we investigated optimal flower longevity, the proportion of reward and rewardless flowers, and honest- and dishonest-signalling strategies. We found that honest signals are evolutionarily stable only when flowers are visited by pollinators with both high and low learning abilities. These findings imply that behavioural variation in learning within a pollinator community can lead to the evolution of an honest signal even when there is no contribution of rewardless flowers to pollinator attractiveness.     

具有时滞的非自治差分竞争系统的渐近行为研究(英文)

提出了一个具有时滞的非自治差分竞争系统.分别利用差分不等式及Lyapunov离散函数技巧,得到了系统永久持续生存和正解全局吸引的充分条件.数值模拟验证了理论结果的正确性.     

害虫生物防治的数学模型

文章讨论一类捕食者（天敌）具脉冲放养与食饵（害虫）具阶段结构时滞的捕食-食饵模型,得到了害虫灭绝周期解全局吸引的充分条件和害虫的密度可以控制在经济危害水平E（EIL）之下的脉冲存放周期．为现实的害虫管理提供一定的理论依据．     

Olfactory responses of tsetse flies to phenols from buffalo urine

Abstract A comparison was made of the EAG responses of males and females of Glossina morsitans morsitans Westwood, G.austeni Newstead and G.tachinoides , Westwood to various doses of compounds known to be components of ox and buffalo urine fractions which are attractive to tsetse in the field (phenol, 3- and 4-methylphenol, 3- and 4-ethylphenol, 4-n-propylphenol, dimethylsulfone). All three species did not respond to dimethylsulfone. The overall responses to the phenolic substances were higher in females than in males in G.m.morsitans and higher in males than in females in G.austeni and G.tachinoides. Response spectra of the species for the phenolic substances suggested that G.m.morsitans and G. austeni were most responsive to 3- and 4-methylphenol and 3-ethylphenol, whereas G. tachinoides was most sensitive to 3-ethylphenol and 3-methylphenol, and only moderately sensitive to 4-methylphenol.
Cross-adaptation experiments, in which l-octen-3-ol, acetone, 4-heptanone and 3-nonanone were also included, revealed that all phenolic compounds stimulated one and the same class of receptors, which differed from the class of receptors activated by l-octen-3-ol. The ketones also had their own receptors. Hence, the flies can obtain information about the presence of attractants by at least three different receptor classes. It was concluded that phenol and any individual alkylphenol found in ox and buffalo urine should be attractive to tsetse flies, provided that stimulus intensity is above threshold and not beyond optimum. One class of receptors may respond more strongly in males than in females, whereas another class is more responsive in females than in males. This may result in a change in sex ratios in catches depending on the odour bait used.     

带有食饵保护的Gause型扩散捕食系统的稳定性分析

考虑了具有扩散项和食饵保护的Gause型捕食系统.该模型带有齐次Neumann边界条件.讨论了系统的全局吸引性以及系统非负常数平衡态的局部稳定性和全局稳定性.其条件依赖于食饵保护参数,表明了食饵保护对系统动力学行为的影响.     

非自治阶段结构合作系统的持久性与周期解

本文研究一类非自治阶段结构的合作系统,得到系统的最终有界性,对应周期系统正周期解的存在性,唯一性以及全局渐近稳定性的充分条件。     

具有脉冲和Holling Ⅲ类功能反应的捕食系统的持续生存和周期解

利用含脉冲的比较原理和分段Lyapunov方法,讨论了具有脉冲项和Holling Ⅲ类功能反应的捕食系统的持续生存性、周期解的存在唯一性和全局吸引性,给出了保持这些性质时脉冲项应满足的界限,系统的特例改进了相关文献所得结果。