Synthesis of Shape‐Persistent Macrocycles with Three 1,8‐Diazaanthracene Units and Their Packing in the Single Crystal

The synthesis of four shape‐persistent macrocycles with three 1,8‐diazaanthracene units each is reported ( 2 , 3 a – 3 c ). For two of them single crystals could be obtained and the structures in the crystal be solved. The structures reveal that macrocycle 2 self‐dimerizes in the solid state; surprisingly it also forms a stable dimer in solution. The reason for this is seen in unusually efficient dispersion interactions as a consequence of the large contact areas in the dimer. All macrocycles are assessed as to their applicability in lateral polymerizations in the single crystal as well as in solution.     

Interactional models for adults of two populations with maturation delays

This paper is concerned with interactional models for adults of two species delayed by their mature periods. The existence and local stability of equilibria are discussed thoroughly for competitive systems, cooperative systems and predator-prey systems, respectively. For systems with interaction of competition and cooperation, it is found that the two populations are uniformly persistent if the positive equilibrium is stable. For predator-prey interaction, however, some further conditions are needed to guarantee the persistence of the systems.     

一类具有扩散的捕食系统的持久性

研究了一类具有Michaclis-menten型反应函数的扩散系统的持久性问题,利用比较原理,得到了系统一致持久的充分条件.     

双营养Chemostat模型的渐近性态

研究了含有时滞的双营养chemostat模型的渐近性态.首先利用泛函微分方程的单调理论分析了单种群chemostat模型正平衡点的全局渐近稳定性.对于两种群chemostat模型,利用无限维动力系统的理论给出了该系统一致持续生存的充分条件.     

中国股市波动率变化特征的实证分析

将体制转换模型与广义自回归条件异方差(GARCH)模型相结合,用以对上证综合指数和深圳成分指数进行实证分析.刻画中国股市的波动持续性和体制变化特征,解决单体制GARCH模型的伪高度持续性问题,识别出两市高低波动体制.从分析结果发现,中国股市存在着明显的体制变化特征,高低波动体制显著相异;引进转换体制之后,持续性系数显著降低;T 1体制和涨跌停板制度对于抑制过度投机起着重要作用.     

证券投资基金业绩评估探析

从传统收益—风险评价模型、股票与时机选择能力分析模型、基金业绩的持续性与生存偏差以及其他模型等方面,对基金业绩评估主流思想进行了介绍与总结。     

Simplicial Persistence of Financial Markets: Filtering,Generative Processes and Structural Risk

We introduce simplicial persistence, a measure of time evolution of motifs in networks obtained from correlation filtering. We observe long memory in the evolution of structures, with a two power law decay regimes in the number of persistent simplicial complexes. Null models of the underlying time series are tested to investigate properties of the generative process and its evolutional constraints. Networks are generated with both a topological embedding network filtering technique called TMFG and by thresholding, showing that the TMFG method identifies high order structures throughout the market sample, where thresholding methods fail. The decay exponents of these long memory processes are used to characterise financial markets based on their efficiency and liquidity. We find that more liquid markets tend to have a slower persistence decay. This appears to be in contrast with the common understanding that efficient markets are more random. We argue that they are indeed less predictable for what concerns the dynamics of each single variable but they are more predictable for what concerns the collective evolution of the variables. This could imply higher fragility to systemic shocks.     

JAIN SLEE中异步持久化方案的设计与实现

JAIN SLEE是一种异步、事件驱动的融合网络应用环境核心,其可靠性需要持久化方案来保存并恢复业务处理组件的相关状态,但目前缺少JAIN SLEE异步持久化技术．本文提出一种异步持久化方案,并设计和实现了持久化资源适配器,经测试方案能保障JAIN SLEE的可靠性,且相比J2EE成熟的同步持久化方案,具有更高的性能．     

Dynamic Analysis of an Impulsive Chemostat Model with Microbial Competition and Nonlinear Perturbation

In this paper, we propose an impulsive chemostat model with microbial competition and nonlinear perturbation. First, thresholds for the extinction of both microoganisms are given. Second, we investigate the persistence in mean and boundedness of the chemostat system by constructing Lyapunov function. Moreover, we obtain the sufficient condition for the existence of an ergodic stationary distribution of the system. At last, numerical simulations are presented, and the results show that the competition between two species tends to make one species disappear from their common habitat, especially when the competition is concentrated in a single resource.     

Dynamical Behavior of a Stochastic Nutrient-Plankton Food Chain Model with L\''{e}vy Jumps

In aquatic ecosystem, plankton populations are easily affected by environmental fluctuations due to the unpredictability of many physical factors. To better understand how environmental fluctuations influence plankton populations, in this paper, we propose and investigate a stochastic nutrient-plankton food chain model with L$\acute{\rm e}$vy jumps. Firstly, by constructing a suitable Lyapunov function, we prove that the stochastic model has a unique global positive solution for any given positive initial value. Then, we establish sufficient conditions for the persistence and extinction of plankton. Finally, we provide some numerical simulations to illustrate the analytical results.