Collective Behavior

Models of active Brownian motion in two-dimensional (2D) systems developed earlier are investigated with respect to the influence of linear attracting forces and external noise. Our consideration is restricted to the case that the driving is rather weak and that the forces show only weak deviations from radial symmetry. In this case an analytical study of the bifurcations of the system is possible. We show that in the presence of external linear forces with only small deviations from radial symmetry, the system develops rotational excitations with left-right symmetry, corresponding to limit cycles in the 4D phase space, the corresponding distribution has the form of a hoop or a tire in the 4D space. In the last part we apply the theory to swarms of Brownian particles that are held together by weak and attracting forces, which lead to cluster formation. Since near the center the potential is at least approximately parabolic and near to the radial symmetry, the swarm develops rotation...

... Phys. 121 4246. [55] Ramos JAP, Granato E, Achim CV, Ying SC, Elder KR and Ala-Nissila T 2008 Phys. Rev. E 78 031109. ... Rev. E 76 056706. [79] Jaatinen A, Achim CV, Elder KR and Ala-Nissila T 2009 Phys. Rev. E 80 031602. [80] Chu MW et al 2004 Nat. Mater. 3 87. ...

Книга «Политика толп: альтернативная история социологии» Кристиана Борха посвящена исследованию истории появления и развития «семантики» толп. Датский социолог решает сложную задачу по реконструкции широкой научной дискуссии, которая разворачивалась вокруг концептов «масса» и «толпа», а также анализу социально-политических условий, которые повлияли на ее развитие. Повествование затрагивает эволюцию семантики толп во Франции, Германии и США и обращается к общему анализу развития теорий коллективного поведения и массового общества. Автор указывает нa то, что центральные идеи классической семантики толп, такие как иррациональность, де-индивидуализация, «ненормальность» массовой активности вступили в противоречие с либеральной программой современности (modernity), основанной на ценностях индивидуализма и рациональности.  К явным достоинствам рецензируемой книги относятся большой объем использованных литературных источников, анализ различных и сложно сочетаемых друг с другом элементов семантики толп, оригинальное и органичное структурирование содержания работы. К сожалению, автор оставляет недосказанными некоторые делали рассматриваемой им истории – например современное обсуждение толп в контексте появления технологий «краудсорсинга». Он также не всегда однозначно аргументирует свои суждения относительно взглядов на толпу или массу в некоторых из анализируемых им теорий. Тем не менее, «Политика толп», заслуживает внимания читателя. Данная книга представляет научной аудитории новый взгляд на историю семантики толп и затрагивает широкий контекст, демонстрируя нелинейность и многоаспектность истории социальной мысли XX века.

Social networks rely on basic rules of conduct to yield functioning societies in both human and animal populations. As individuals follow established rules, their behavioral decisions shape the social network and give it structure. Using dynamic, self-organizing social network models we demonstrate that defying conventions in a social system can affect multiple levels of social and organizational success independently. Such actions primarily affect actors' own positions within the network, but individuals can also affect the overall structure of a network even without immediately affecting themselves or others. These results indicate that defying the established social norms can help individuals to change the properties of a social system via seemingly neutral behaviors, highlighting the power of rule-breaking behavior to transform convention-based societies, even before direct impacts on individuals can be measured.

In this work we study the collective behaviors arising in a model of a simplified homogeneous society. Each agent is modeled as a binary ``perceptron'', receiving neighbors' opinions as inputs and outputting one of two possible opinions, according to the conformist attitude and to the external pressure of mass media. For a neighborhood size greater than three, the system shows a very complex phase diagram, including a disordered phase and chaotic behavior. We present analytic calculations, mean fields approximation and numeric simulations for different values of the parameters.

Locating the source of an advected chemical signal is a common challenge facing many living organisms. When the advecting medium is characterized by either high Reynolds number or high Peclet number the task becomes highly non-trivial due to the generation of heterogenous, dynamically changing filamental concentrations which do not decrease monotonically with distance to the source. Defining search strategies which

This paper presents an analysis of avoidance strategies developed by small-scale
shrimp fishermen in response to externally imposed regulations that limit their access to
marine resources. The main issue that will be explored is whether fishermen act as
individuals who calculate costs and benefits associated with noncompliance; or as
community members who break the rules in order to serve collective interests within the
communities.

Cette article présente une analyse des stratégies developpées par les pêcheurs de
crevettes à petite échelle en réponse à des réglementations imposés de l'exterieur qui
limitent leur accès au resources marines, ces stratégies consistent à échapper aux
régulations en vigueur. La question principale qui sera investiguée consiste à savoir si les
pêcheurs agissent en tant qu'individus qui calculent coûts et bénéfices associés avec le
non-respect de régulations externes; ou comme membres de la communauté qui rompent
les régles pour le bénéfice de la communauté.

Este artículo representa un análises de las estrategias desarrolladas por los pescadores
de camaron en menor escala como respuesta a las regulaciones externamente impuestas
que limitan su aceseso a los recursos marinos. El tema principal que se va a explorar es
que si los pescadores actúan como individuos que calculan los costos y beneficios
asociados con el implemento de las leyes o regulaciones, o, como miembros de una
comunidad quienes rompen las reglas con fin de servir los intereses colectivos dentro de
sus comunidades.

Research on collective emotions has been limited until recently to theories of irrational crowds, scepticism about genuinely group-level psychological phenomena and analyses of the unconscious or ritual sources of mass affective experience. However, collective emotion is now a thriving research area that combines studies from philosophy, anthropology, sociology, social psychology and neuroscience. This article examines neo-Durkheimian theories of collective emotions and relevant contributions of discursive psychologists and other social scientists influenced by the “turn to affect.” I argue that future theoretical and empirical investigations should do the following: (1) critically examine theories focusing on diffuse emotional energy and discrete collective emotions by also exploring the generation and production of genuinely collective mixed emotions; (2) clarify problems with “bottom-up” models of causal mechanisms through exploration of “affective practices”; and (3) explore the implications of Tuomela's (2013) “top-down” social ontology of “group agents” as a framework for theories and studies of collective emotion.

Cancer cell collective migration is a complex behaviour leading to the invasion of cancer cells into surrounding tissue, often with the aid of stromal cells in the microenvironment, such as macrophages or fibroblasts. Although tumour–tumour and tumour–stromal intercellular signalling have been shown to contribute to cancer cell migration, we lack a fundamental theoretical understanding of how aggressive invasion emerges from the synergy between these mechanisms. We use a computational self-propelled particle model to simulate intercellular interactions between co-migrating tumour and stromal cells and study the emergence of collective movement. We find that tumour–stromal interaction increases the cohesion and persistence of migrating mixed tumour–stromal cell clusters in a noisy and unbounded environment, leading to increased cell cluster size and distance migrated by cancer cells. Although environmental constraints, such as vasculature or extracellular matrix, influence cancer migration in vivo, our model shows that cell–cell interactions are sufficient to generate cohesive and persistent movement. From our results, we conclude that inhibition of tumour–stromal intercellular signaling may present a viable therapeutic target for disrupting collective cancer cell migration.

Michael Bratman has proposed an intention-based account of shared agency. He advocates the benefits of the individual planning theory of agency in explaining both normative and conceptual aspects of cooperative behavior. While refusing to rely on metaphysical structures of collective intentionality, such as Searle’s We-intentions, the planning theory of agency focuses primarily on the psychological continuity between individual and social norms of rationality and planning. This article tries to assess the merits of Bratman’s proposal also by taking into account some competing views such as those of Searle and Gilbert.

Inspired by Weber’s charismatic carrier groups, Eisenstadt coined the term institutional entrepreneur to capture the rare, but epochal individual capable of reorienting a group’s value-orientations and transferring charisma, while making them a force of structural and cultural change. As a corrective to Parsons’ abstract, ‘top-down’ theory of change, Eisenstadt’s theory provided historical context and agency to moments in which societies experienced qualitative transformation. The concept has become central to new institutionalism, neo-functionalism, and evolutionary-institutionalism. Drawing from the former two, a more robust theory of institutional entrepreneurship from an evolutionary-institutionalist’s perspective is posited. Taking seriously Eisenstadt’s observation that entrepreneurs were the sociocultural analogy to biological mutation, this paper elucidates a group selectionist theory of macrosociological evolution. In essence, entrepreneurs formulate institutional projects with dual-logic: a collective side focused on innovation where efforts are directed towards organizational-symbolic mechanisms of integration and a self-interested side directed towards resource-independence, monopolization, mobility, and power-dependence. While outcomes vary based on numerous biotic/environmental factors, success leads to (1) greater structural/symbolic independence and (2) ability to reconfigure physical-temporal-social-symbolic space.

This paper examines the rules set out by a series of imperial charters issued to the cives of Mantua in the eleventh and early twelfth centuries. It argues that these rules were initially more important for their ability to convey the authority of the emperor than for the rights and protections they provided to their recipients. Indeed, these rules were often broken and the rights of the cives were repeatedly disregarded by the Canossan family who dominated the city. However, I will also argue that over the course of this period the rules entailed in these documents increasingly came to reflect realities in Mantua and the growing role of the cives on the political stage.

During the 1970s Keller codified a Ständeordnung (social order) in the cities of Italy in the ninth to twelfth centuries dividing political society into three ordines: the capitanei (high nobility), valvassores (low nobility) and populus (non nobles). This model has had a great impact on historians’ presentation of urban society in the precommunal and communal period and much of the debate of the last thirty years has hinged around how extensively similar models can be applied throughout the cities of Italy. My thesis critiques this discussion, arguing that too much emphasis has been placed on identifying and defining social groups within this period without fully considering the political motivations, social preconceptions and rhetorical techniques of the authors of the medieval texts. I focus on Mantua and Parma and investigate a series of case studies looking at the political and rhetorical strategies pursued by the authors of the sources. This comparative approach is novel and balances a tendency to address the Italian communes either individually or as regional surveys. The use of case studies allows a deeper analysis than the general surveys common to this topic are able to provide. I have reassessed incidents in Mantua and Parma and demonstrated that a number of factors affected different authors’ choices during this period, and that these factors changed over time: most notably from rhetorical need to descriptions of politically activity. Furthermore, I argue that urban collective action was often undertaken by a conglomeration of those who could be defined as any of the ordines described by Keller and others. This has implications for the applicability of Ständeordnung in other cities in Northern Italy which share similar political situations and documentation with Mantua or Parma, suggesting that these social models may need to be redefined. My thesis does not overturn the concept of Ständeordnung but refines it in an original manner contributing a new aspect to the debate.

Le organizzazioni costruiscono un sapere. Nella loro complessità mettono in circolazione una quantità incredibile di informazioni e saperi che quotidianamente vanno a costruire, con la consapevolezza più o meno attiva degli individui, il bagaglio di conoscenze dell’organizzazione stessa. Così come i popoli e le società danno origine, armonizzano e rappresentano la propria cultura e i propri costumi, allo stesso modo le organizzazioni di persone generano conoscenza. Ora, più l’organizzazione incrementa la sua estensione, nello spazio (diventa più grande) e nel tempo (diventa più vecchia), più la serie e i flussi di informazioni e rappresentazioni si moltiplicano e nella molteplicità si disperdono tra la numerosità degli individui.

In trying to understand the development of cultural complexity in Peru during the Late Archaic Period (3,000-1,800 B.C.) scholars have struggled to adequately categorize the types of societies that existed along the north central coast in a region known as the Norte Chico. While the utility of such labels is debatable, the elements of Late Archaic societies typically used to understand social complexity are not those commonly associated with traditional anthropological models of emerging authority. Instead, the distinction between wealth finance and staple finance as methods to mobilize surplus may explain some of the apparently anomalous aspects of Late Archaic political and economic organization in the Norte Chico. In this alternative model, emergent leaders of irrigation-based Norte Chico polities use religious ideologies to emphasize group membership through ritually mobilized staple finance rather than a strategy that emphasizes hierarchical principles.

The fear of an invasion from an advanced alien civilization is increasingly prevalent in human society. The current paper is a discussion on the motivations for this irrational fear considered to stem from the deficient vantage point from which the subject is analyzed by the human mind. It will be shown that contrary to popular culture, species in the universe must follow an inevitable course towards an absolute peaceful society and that such attitude must be true across the universe without exception, which leads into the argumentation of an as of yet poorly explored explanation for the Fermi paradox called the Cosmic Quarantine Hypothesis. Furthermore, the discussion explores the convergence of the definition of “kin” towards compatibility between behavior and attitude rather than physiological compatibility which is argued to be transitory. The universal convergence of behavior towards peacefulness and that of kin towards behavior, give rise to a universal super-species and as such concepts like racial interest, invasion or xenophobia completely loose their significance.

Selection on the level of loosely associated groups has been suggested as a route towards the evolution of cooperation between individuals and the subsequent formation of higher-level biological entities. Such group selection explanations remain problematic, however, due to the narrow range of parameters under which they can overturn within-group selection that favours selfish behaviour. In principle, individual selection could act on such parameters so as to strengthen the force of between-group selection and hence increase cooperation and individual fitness, as illustrated in our previous work. However, such a process cannot operate in parameter regions where group selection effects are totally absent, since there would be no selective gradient to follow. One key parameter, which when increased often rapidly causes group selection effects to tend to zero, is initial group size, for when groups are formed randomly then even moderately sized groups lack significant variance in their composition. However, the consequent restriction of any group selection effect to small sized groups is derived from models that assume selfish types will competitively exclude their more cooperative counterparts at within-group equilibrium. In such cases, diversity in the migrant pool can tend to zero and accordingly variance in group composition cannot be generated. In contrast, we show that if within-group dynamics lead to a stable coexistence of selfish and cooperative types, then the range of group sizes showing some effect of group selection is much larger.

Constant re-evaluation of social affiliations and shifting social network structures can profoundly affect the adaptive fitness of individuals within a population, as well as yielding super-additive effects felt by the population as a whole. To evaluate the impact of different social affiliation choices, and the relative ability of individuals to correctly assess the success of other individuals, we have created a set of mathematical models based on network centrality measures. We choose the hypothetical measures of "popularity", "closeness" and "betweenness" to examine the resulting self-organizations of social groups. Our findings suggest that some different types of social behaviors can lead to the same levels of stability and organizational success, suggesting the possibility that complex organizations could have evolved from simpler ones without any change in the selective pressures acting on the population.

"Few problems have created the combined interest of so many unrelated areas as the evolution of cooperation. As a result, several mechanisms have been identified to work as catalyzers of cooperative behavior. Yet, these studies, mostly grounded on evolutionary dynamics and game theory, have neglected the important role played by intention recognition in behavioral evolution. Here we address explicitly this issue, characterizing the dynamics emerging from a population of intention recognizers. We derive a Bayesian Network model for intention recognition in the context of repeated social dilemmas and evolutionary game theory, by assessing the internal dynamics of trust between intention recognizers and their opponents. Intention recognizers are then able to predict the next move of their opponents based on past direct interactions, which, in turn, enables them to prevail over the most famous strategies of repeated dilemmas of cooperation,
even in presence of noise. Overall, our framework offers new insights on the complexity and beauty of behavioral evolution driven by elementary forms of cognition."

Social networks rely on basic rules of conduct to yield functioning societies in both human and animal populations. As individuals follow established rules, their behavioral decisions shape the social network and give it structure. Using dynamic, self-organizing social network models we demonstrate that defying conventions in a social system can affect multiple levels of social and organizational success independently. Such actions primarily affect actors' own positions within the network, but individuals can also affect the overall structure of a network even without immediately affecting themselves or others. These results indicate that defying the established social norms can help individuals to change the properties of a social system via seemingly neutral behaviors, highlighting the power of rule-breaking behavior to transform convention-based societies, even before direct impacts on individuals can be measured.

This Perspective describes recent progress in the development of functional magnetic nanoparticle assemblies. After describing the formation of two- and three-dimensional particle arrays in terms of the size-dependent driving forces, we focus on magnetic nanoparticle arrays. We discuss how the self-organized structure can modify the magnetic behavior, relative to that of isolated particles. We highlight an important development, described in this issue of ACS Nano by Kostiainen and co-workers, who have demonstrated not only the novel aqueous self-assembly of magnetic particles but also controlled and reversible disassembly. Finally, we explore two inter-related future directions for self-assembly of magnetic nanoparticles: the formation of more complex, hierarchical structures and the integration of self-assembly with fabrication techniques for electronic devices.

One of the steps usually undertaken in the formation of partnerships is the assessment of organisations’ competencies. The typical notion of competencies, which have a functional or technical nature and provide specific outcomes, refers, in fact, to what can be considered as hard competencies. However, the very act of collaboration has its specific requirements, for which the involved organisations must be apt to exercise other types of competencies that affect their own performance and the success of the partnership. These competencies are more of a behavioural nature, and can be named as soft competencies. This study aims at addressing the
effects of the soft competencies on the performance of the hard ones. An extended competencies model is thus proposed, allowing the construction of adjusted competencies profiles, in which the competency levels are dynamically determined according to the requirements of collaboration opportunities. The idea of competencies fitness arises from this adjustment, allowing better selection of partners.