Boom and bust in continuous time evolving economic model

We show that a simple model of a spatially resolved evolving economic system, which has a steady state under simultaneous updating, shows stable oscillations in price when updated asynchronously. The oscillations arise from a gradual decline of the mean price due to competition among sellers competing for the same resource. This lowers profitability and hence population but is followed by a sharp rise as speculative sellers invade the large un-inhabited areas. This cycle then begins again.     

Synchronization in evolving snowdrift game model

The interaction between the evolution of the game and the underlying network structure with evolving snowdrift game model is investigated. The constructed network follows a power-law degree distribution typically showing scale-free feature. The topological features of average path length, clustering coefficient, degree-degree correlations and the dynamical feature of synchronizability are studied. The synchronizability of the constructed networks changes by the interaction. It will converge to a certain value when sufficient new nodes are added. It is found that initial payoffs of nodes greatly affect the synchronizability. When initial payoffs for players are equal, low common initial payoffs may lead to more heterogeneity of the network and good synchronizability. When initial payoffs follow certain distributions, better synchronizability is obtained compared to equal initial payoff. The result is also true for phase synchronization of nonidentical oscillators.     

Socio-economical dynamics as a solvable spin system on co-evolving networks

We consider social systems in which agents are not only characterized by their states but also have the freedom to choose their interaction partners to maximize their utility. We map such systems onto an Ising model in which spins are dynamically coupled by links in a dynamical network. In this model there are two dynamical quantitieswhich arrange towards a minimum energy state in the canonical framework:the spins, s_i, and the adjacency matrix elements, c_ij.The model is exactly solvable because microcanonical partition functions reduce to productsof binomial factors as a direct consequence of the c_ij minimizing energy. We solve the system for finite sizes and for the two possible thermodynamic limits and discussthe phase diagrams.     

Interplay of noise and coupling in heterogeneous ensembles of phase oscillators

We study the effects of noise on the collective dynamics of an ensemble of coupled phase oscillators whose natural frequencies are all identical, but whose coupling strengths are not the same all over the ensemble. The intensity of noise can also be heterogeneous, representing diversity in the individual responses to external fluctuations. We show that the desynchronization transition induced by noise may be completely suppressed, even for arbitrarily large noise intensities, is the distribution of coupling strengths decays slowly enough for large couplings. Equivalently, if the response to noise of a sufficiently large fraction of the ensemble is weak enough, desynchronization cannot occur. The two effects combine with each other when the response to noise and the coupling strength of each oscillator are correlated. This combination is quantitatively characterized and illustrated with explicit examples.     

Cost estimation algorithm and decision-making model for curriculum modification in educational organization

The decision about curriculum modification usually takes place at the knowledge level, mainly with consideration of individual academic staff competences and qualifications. However, traditional approaches to cost estimation of curriculum modification are focused on material resources only. In this paper we present a cost estimation method and decision model for curriculum modification in educational organizations. The proposed method works at the knowledge level and employs competence sets as knowledge representation models in educational organizations. Authors used the theory of hierarchical, multilevel systems in order to define the model of the decision-making process of curriculum modification and its dimension. Basing on this and also using a fuzzy competence model the cost estimation algorithm in the form of a group competences expansion algorithm is proposed. The algorithm focuses on the cost of staff competence expansion caused by the knowledge development process.     

街区土地利用、交通供给特征与大型超市购物出行模式研究

基于杭州城西9个街区1 365份大型超市出行数据,利用居民个体属性、出行距离和土地利用特征3组变量,构建了多项逻辑斯蒂克决策模型,分析了街区土地利用特征对大型超市出行模式的影响.结论为大城市街区的“可达性提高”和“商住混合度增加”,可以明显提高大型超市出行的步行(2 km内)、自行车(4 km内)选择概率;公交服务水平的提升可鼓励大型超市出行的非机动化,但公交密度本身不足以抑制小汽车的选择.提出在“社区商圈”尺度中,有必要遵循空间组织的渐进规划思路,通过“土地利用-交通”一体化措施,优化大型超市的出行结构.     

企业研发组织沟通网络实证及优化策略研究

鉴于企业研发组织内部沟通网络对研发组织中高效、低成本地实现技术信息共享的重要性,本文首先介绍了结构洞的测度方法,并对中间中心性方法进行改进;其次分析了某企业研发组织沟通网络的结构洞情况,指出非正式沟通网络和专业沟通网络的相关性;然后通过比较改进的中心度算法、传统的中心度算法与限制度指标的相似性,验证了该算法的有效性;最后提出一种削弱沟通网络中“核心人物”垄断地位的“搭桥”策略。结果发现:改进的中心度算法适用于带权值沟通网络结构洞的测定,验证了该算法加权方法的有效性,并给出通过非正式组织促进技术信息共享的对策     

Network ecology: topological constraints on ecosystem dynamics

Ecological systems are complex assemblages of various species with interactions between them. The interactions can be even more important than the species themselves for understanding how the whole system is functioning and organized. For the representation of the topological space of interspecific relationships, graph theory is a suitable mathematical tool: the network perspective and the various techniques of network analysis are more and more elaborated and invading ecology. Beyond a static view on networks, fundamental questions can only be answered if dynamical analyses are also made, and now it is clear that structural and dynamical studies must not “compete” but strongly complement each other. Our aim is to give a menu of classical and more recently suggested network indices and to discuss what do we know about their relations to ecosystem dynamics. Since ecologists have very diverse problems, they need diverse techniques and a good insight in matching the adequate method to a particular problem. The main question is how to link certain graph properties to understanding and predicting the behaviour of an ecosystem. We wish to contribute to bridging the gap between extreme structural and extreme dynamical views.     

Fabrication of Nanofiber Scaffolds With Gradations in Fiber Organization and Their Potential Applications

A new and simple method for fabrication of nanofiber scaffolds with gradations in fiber organization is reported. The nanofiber organization, achieved by deposition of random fibers on the uniaxially aligned nanofiber mat in a gradient manner, directed morphological changes of applied adipose‐derived stem cells. These morphological changes and resultant biochemical changes can help mimic the structural orientation of complex biomechanical structures like the collagen fiber structure at the tendon‐to‐bone insertion site. In addition, chemical gradients can be established through nanoencapsulation in this novel scaffold allowing for enhanced biomedical applications.

     

Pre-organization of the core structure of E-selectin antagonists

A new class of N-acetyl-D-glucosamine (GlcNAc) mimics for E-selectin antagonists was designed and synthesized. The mimic consists of a cyclohexane ring substituted with alkyl substituents adjacent to the linking position of the fucose moiety. Incorporation into E-selectin antagonists led to the test compounds 8 and the 2'-benzoylated analogues 21, which exhibit affinities in the low micromolar range. By using saturation transfer difference (STD)-NMR it could be shown that the increase in affinity does not result from an additional hydrophobic contact of the alkyl substituent with the target protein E-selectin, but rather from a steric effect stabilizing the antagonist in its bioactive conformation. The loss of affinity found for antagonists 10 and 35 containing a methyl substituent in a remote position (and therefore unable to support to the stabilization of the core) further supports this hypothesis. Finally, when a GlcNAc mimetic containing two methyl substituents (52 and 53) was used, in which one methyl was positioned adjacent to the fucose linking position and the other was in a remote position, the affinity was regained.