周密. / "2007年9月". / 論文(哲學碩士)--香港中文大學, 2007. / 參考文獻(leaves 110-115). / "2007 nian 9 yue". / Abstract also in English. / Zhou Mi. / Can kao wen xian (leaves 110-115). / Lun wen (zhe xue shuo shi)--Xianggang Zhong wen da xue, 2007. / Chapter 第一章、 --- 引言 --- p.1 / Chapter 第二章、 --- 互聯網與集體行爲 --- p.7 / Chapter 第三章、 --- 中國的網絡控制 --- p.20 / Chapter 第四章、 --- 網上集體行爲的形成：“野百合´ح的個案 --- p.38 / Chapter 第五章、 --- 高校BBS實名製作爲網絡控制：産生網上對抗性集體行爲的動因 --- p.74 / Chapter 第六章、 --- 結論與討論 --- p.106 / 参考文献 --- p.110

Suspensions of the aerobic bacteria {\it Bacilus subtilis} develop patterns and flows from the interplay of motility, chemotaxis and buoyancy.In sessile drops, such bioconvectively driven flows carry plumes down the slanted meniscus and concentrate cells at the drop edge, while in pendant drops such self-concentration occurs at the bottom.These dynamics are explained quantitatively by a mathematical model consisting of oxygen diffusion and consumption, chemotaxis, and viscous fluid dynamics.Concentrated regions in both geometries comprise nearly close-packed populations, forming the collective ``Zooming BioNematic'' (ZBN) phase.This state exhibits large-scale orientational coherence, analogous to the molecular alignment of nematic liquid crystals, coupled with remarkable spatial and temporal correlations of velocity and vorticity, as measured by both novel and standard applications of particle imaging velocimetry.To probe mechanisms leading to this phase, response of individual cells to steric stress was explored, finding that they can reverse swimming direction at spatial constrictions without turning the cell body.The consequences of this propensity to flip the flagella are quantified, showing that "forwards" and "backwards" motion are dynamically and morphologically indistinguishable.Finally, experiments and mathematical modeling show that complex flows driven by previously unknown bipolar flagellar arrangements are induced when {\it B. subtilis} are confined in a thin layer of fluid, between asymmetric boundaries.The resulting driven flow circulates around the cell body ranging over several cell diameters, in contrast to the more localized flows surrounding free swimmers.This discovery extends our knowledge of the dynamic geometry of bacteria and their flagella, and reveals new mechanisms for motility-associated molecular transport and inter-cellular communication.

The purpose of this thesis is to understand the concept of collective behavior from different theoretical perspectives and the policy implications they imply for the Turkish Riot Police Units. The civil disturbances in the 1960s have clearly illustrated range of problems in the domain of crowd control. This work will start with the general characteristics and the classification of collective behavior. Second, two main perspectives on collective behavior, which are the structuralist and the interactionist perspectives, will be examined respectively. The question will be asked whether these two perspectives efficiently and effectively explain the crowds and the crowd control. Finally, the other factors in crowd control will be explored, and recommendations concerning the handling of crowds in a more peaceful manner will be made.

No description available.

Cities are complex systems of transportation and social activity; their structure can be used to model urban street networks i.e. complex network that represents the geometry of a city allowing analytical activities for data-driven decision-making. The geometry of a city holds intrinsic information that can support activities related to the analysis of the urban scenario; of higher importance is the use of such information to enhance the quality of life of its inhabitants and/or to understand the dynamics of an urban center. Several of these analytical processes lacks in-depth methodologies to analyze crime patterns and ill-designed urban structures, which can provide for public safety and urban design. Consequently, it is our goal to provide means for the structural and topological analysis of highly criminal regions of cities represented as complex networks, and for the identification of urban planning inconsistencies that point to regions that lack access from/to points of interest in a city. In this regard, we devised a set of algebraic and algorithmic procedures that are capable of revealing patterns and provide for data comprehension. More specifically, we introduced pre-processing techniques to transform georeferenced electronic maps into graph representations of cities; we used metric-based and epidemic processes to understand the dynamics of cities in what refers to criminality; finally, we introduced a novel set of formalisms and operations based on set theory to identify design flaws concerning access in urban centers. Our results refer to approaches to preprocess and prepare maps in the form of urban street networks; to the analyses of crimes based on their spatial disposition; to the development of a model to describe criminal activities; and, to the advance of a concept based on critical problems in the urban design. / As cidades são sistemas complexos de interação social e de transporte. Suas estruturas podem ser usadas para modelar redes de mobilidade urbana i.e. redes complexas que representam a geometria de uma cidade permitindo a consecução de atividades analíticas para descoberta de padrões e para a tomada de decisão baseada em dados. A geometria da cidade carrega informações intrínsecas que auxiliam atividades relacionadas à análise de dados provenientes do cenário urbano. As informações inerentes a tais análises podem ser usadas para melhorar a qualidade de vida dos habitantes de uma região, ou para entender a dinâmica de centros urbanos. Diversos processos analíticos aplicados a tais cenários carecem de metodologias para analisar o padrão criminal e para identificar estruturas urbanas mal planejadas. Deste modo, este trabalho tem por objetivo prover meios para análise topológica de regiões criminais e para a identificação de inconsistências urbanas, as quais apontam para regiões que carecem de mobilidade e acesso para outras regiões de uma cidade. Neste sentido, foi desenvolvido um conjunto de procedimentos algébricos e algorítmicos capazes de revelar padrões e meios para compreensão e análise dos dados. Mais especificamente, foram desenvolvidos métodos de pré-processamento para transformar mapas eletrônicos georreferenciados em grafos que representam cidades, foi utilizado um conjunto métrico analítico e outro com base em processos epidêmicos para entender a dinâmica intrínseca à criminalidade de uma cidade, e por fim, foi desenvolvido um conjunto de formalismos e operações baseados em teoria dos conjuntos para identificar falhas no desenho das estruturas urbanas que impactam no acesso viário em centros urbanos. Os resultados deste trabalho versam sobre o desenvolvimento de novos métodos para preparar mapas na forma de redes de mobilidade urbana; na análise de crimes baseada em sua disposição espacial; no desenvolvimento de um modelo capaz de descrever a atividade criminal de uma cidade; e, em um conceito baseado na análise de regiões críticas identificadas a partir do desenho urbano.

O comportamento coletivo das formigas é produto de processos auto-organizados, ou seja, as unidades constituintes, cada um dos indivíduos da colônia, age de modo descentralizado, seguindo suas próprias \"regras\" e respondendo aos estímulos do ambiente ao seu entorno. A ação coletiva desses indivíduos produz padrões emergentes complexos e organizados, como no caso das trilhas de forrageio. No presente trabalho investigamos experimental e teoricamente as \"regras\" envolvidas no comportamento de forrageio das formigas e tentamos preencher lacunas teóricas relacionadas a esse comportamento. Nesse contexto o trabalho se compõe de uma revisão acerca das evidências experimentais que permitem tratar dos processos envolvidos na auto-organização em formigas, dois experimentos que tratam da tomada de decisão das formigas em condições que permitem avaliar a flexibilidade comportamental em condições que o modelo comportamental vigente de respostas inflexíveis foi avaliado e um modelo teórico acerca da organização coletiva. Os achados experimentais permitem agregar novas evidências sobre a flexibilidade comportamental de formigas na modulação do recrutamento e formação de trilhas bifurcadas e a dinâmica de atividade envolvendo indivíduos de diferentes tamanhos / Ant´s collective behavior is product of self-organized process. In other words, each unit of a system acts independently, following their own \"rule\" and responding to environment stimuli. The collective action of these individuals produces complex and organized emergent patterns, as can be observed on foraging behavior. When these units work together, they can produce extremely complex and organized patterns, like what occurs in a foraging trail. In the present work we investigate the \"rules\" related to foraging behavior of ants, and we try to solve some theoretical puzzles related to this behavior. The work is composed of a review about the processes involved in the self-organization in ants and the consequences of using a mosaic of evidences; two experiments that deal with the decision making that allow to evaluate the model of inflexible answers; and a theoretical model on collective organization. The experimental findings allow us to add new evidence about ant behavioral flexibility in modulating the recruitment and formation of bifurcated trails and the dynamic of activity involving workers of different sizes

With the cessation of cooperation between groups or individuals comes the threat that temporary competition transforms into destructive intractable conflict. To better understand how intractable conflicts develop, Liebovitch, Naudot, Vallacher, Nowak, Bui-Wrzosinksa, and Coleman (2008) recently developed a non-linear model of two-actor cooperation-competition incorporating interaction feedback and valence. This study tested their model's predictions by investigating attitude and valence change depending on whether a social exchange was cooperative or competitive. Participants experiencing an exchange that switched from cooperation to competition exhibited greater attitude change than participants in the control or the continuously competitive interaction condition and more valence change than the control or competition switching to cooperation condition. These results support the model's prediction that greater attitude and valence fluctuation manifests in interactions transitioning from cooperation to competition, providing the first verification of the model. These findings offer new insights into how human cooperation and competition evolve over time. / by Jay L. Michaels. / Thesis (M.A.)--Florida Atlantic University, 2009. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2009. Mode of access: World Wide Web.

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Orientadora: Maria das Graças Bruno Marietto. / Dissertação (mestrado) - Universidade Federal do ABC. Programa de Pós-graduação em Engenharia da Informação.

The text deals with migration policy. The paper examines the ethical justification for restrictions on migration policy. Follows sections of the historic migration. It focuses on the theme of migration in the biblical context and it try to find basis for restrictions on migration policy in the present. Powered by TCPDF (www.tcpdf.org)