Morphologies and dynamics of the interfaces between active and passive phases

Soft Matter ◽  
2021 ◽  
Author(s):  
Guoqing Xu ◽  
Tao Huang ◽  
Yilong Han ◽  
Yong Chen

Active matters exhibit interesting collective behaviors and novel phases, which provide an important platform for the study of nonequilibrium physics. Mixtures of active and passive particles have been intensively studied...

GEOgraphia ◽  
2018 ◽  
Vol 19 (41) ◽  
pp. 39
Author(s):  
Agripino Souza Coelho Neto

Resumo: O presente texto pretende analisar o papel das ações coletivas (associações, cooperativas e sindicatos de agricultores) no acionamento e na ativação das escalas geográficas para o desenvolvimento de suas atividades. O estudo foi realizado no Espaço Sisaleiro da Bahia (Brasil), onde um conjunto significativo de associações e cooperativas de agricultores e sindicatos de trabalhadores rurais tem se organizado em torno das escalas espaciais para viabilizar sua ação político-institucional e econômico-produtiva. A ação desses coletivos organizados em rede tem permitido a conformação e o fortalecimento de novas escalas de ação política, como no caso da criação do conselho territorial para viabilização da implantação de políticas de governo. Cooperativas, associações e sindicatos se apoiam nas escalas para compor organizações em diferentes níveis escalares (escala local, escala regional, escala do estado federado e escala nacional), buscando fortalecer seus propósitos e ampliar seu poder de barganha e influência. Analisando o comportamento espacial dessas variadas modalidades de ações coletivas, é possível considerar que elas desenvolvem políticas de escala, ou seja, a escala passa a significar muito mais que uma categoria de análise, mas se torna uma categoria da prática social e política. Nesse sentido, parte-se do pressuposto de que os grupos humanos produzem e tornam efetivas suas próprias escalas visando a alcançar suas metas e organizar seus comportamentos coletivos. Palavras-chave: Escala. Rede. Cooperativismo. Associativismo. Sindicalismo. Espaço Sisaleiro da Bahia. SCALE POLICIES AND THE DEVELOPMENT OF NETWORK STRATEGIES OF COLLECTIVE ACTIONS IN THE SISAL REGION OF BAHIA (BRAZIL)Abstract: This paper aims to analyze the role of collective initiatives of associations, cooperatives and farmers’ unions in the mobilization and activation of geographical scales for the development of their activities. The study was conducted in the Sisal Region of Bahia (Brazil), where a significant number of farmers associations and cooperatives and rural workers’ unions have been organizing their actions around spatial scales to enable their political-institutional and economic-productive influence. The gathering and action of these organized groups in a network have allowed the establishment and strengthening of new scales of political action, as seem in the case of the creation of a territorial council to facilitate the implementation of government policies. Cooperatives, associations, and unions rely on scales to form organizations at different scale levels (local, regional, federal and national scales), seeking to strengthen their performance and increase their bargaining power and influence. After analyzing the spatial behavior of these various forms of collective actions, it’s reasonable to say that they develop scale policies, which means the scale becomes more than a category of analysis, but also a category of social and political practice. In this sense, it’s assumed that human groups produce and utilize the scales in order to reach their goals and organize their own collective behaviors. Keywords: Scale. Network. Cooperativism. Associativism. Syndicalism. Sisal Region of Bahia. POLITIQUES D’ÉCHELLE ET FORMATION DES STRATÉGIES-RÉSEAU DES ACTIONS COLLECTIVES DANS LA RÉGION DU SISAL DE L’ÉTAT DE BAHIA Resumé: Cet article analyse le rôle des actions collectives (associations, coopératives et syndicats d’agriculteurs) dans la prise en compte et l’utilisation des échelles géographiques pour le développement de leurs activités. L’étude a été menée dans la région du sisal à Bahia (Brésil), où un ensemble important d’associations et de coopératives d’agriculteurs et de syndicats de travailleurs ruraux se sont organisés autour d’échelles spatiales pour que puisse être mise en place leur action politique et institutionnelle, économique et productive. L’action de ces groupements organisés en réseaux a permis la conformation et le renforcement de nouvelles échelles d’action politique, comme lors de la création du conseil territorial, pour permettre la mise en œuvre des politiques gouvernementales. Les coopératives, les associations et les syndicats prennent les échelles comme point de départ pour former des organisations à différents niveaux scalaires (échelle locale, échelle régionale, échelle fédérée et échelle nationale), dans le but de renforcer leurs objectifs et d’accroître leur pouvoir de négociation et d’influence. Si nous analysons le comportement spatial de ces diverses formes d’action collective il est possible de considérer qu’ils développent des politiques d’échelle, à savoir l’échelle vient signifier bien plus qu’une catégorie d’analyse, puisqu’elle devient une catégorie de la pratique sociale et politique. En ce sens, on suppose que les groupes humains produisent et rendent efficaces leurs propres échelles pour atteindre leurs objectifs et organiser leurs comportements collectifs. Mots-clés: Échelle. Réseau. Coopérativisme. Associations. Syndicalisme. Région du sisal de l’État de Bahia.


2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Katarzyna Bozek ◽  
Laetitia Hebert ◽  
Yoann Portugal ◽  
Greg J. Stephens

AbstractFrom cells in tissue, to bird flocks, to human crowds, living systems display a stunning variety of collective behaviors. Yet quantifying such phenomena first requires tracking a significant fraction of the group members in natural conditions, a substantial and ongoing challenge. We present a comprehensive, computational method for tracking an entire colony of the honey bee Apis mellifera using high-resolution video on a natural honeycomb background. We adapt a convolutional neural network (CNN) segmentation architecture to automatically identify bee and brood cell positions, body orientations and within-cell states. We achieve high accuracy (~10% body width error in position, ~10° error in orientation, and true positive rate > 90%) and demonstrate months-long monitoring of sociometric colony fluctuations. These fluctuations include ~24 h cycles in the counted detections, negative correlation between bee and brood, and nightly enhancement of bees inside comb cells. We combine detected positions with visual features of organism-centered images to track individuals over time and through challenging occluding events, recovering ~79% of bee trajectories from five observation hives over 5 min timespans. The trajectories reveal important individual behaviors, including waggle dances and crawling inside comb cells. Our results provide opportunities for the quantitative study of collective bee behavior and for advancing tracking techniques of crowded systems.


2021 ◽  
Vol 33 (7) ◽  
pp. 076602
Author(s):  
Guo-Liang Peng ◽  
Jun-Jie Zhang ◽  
Jian-Nan Chen ◽  
Tai-Jiao Du ◽  
Hai-Yan Xie

2012 ◽  
Vol 2012 ◽  
pp. 1-24 ◽  
Author(s):  
Erik Cuevas ◽  
Mauricio González ◽  
Daniel Zaldivar ◽  
Marco Pérez-Cisneros ◽  
Guillermo García

A metaheuristic algorithm for global optimization called the collective animal behavior (CAB) is introduced. Animal groups, such as schools of fish, flocks of birds, swarms of locusts, and herds of wildebeest, exhibit a variety of behaviors including swarming about a food source, milling around a central locations, or migrating over large distances in aligned groups. These collective behaviors are often advantageous to groups, allowing them to increase their harvesting efficiency, to follow better migration routes, to improve their aerodynamic, and to avoid predation. In the proposed algorithm, the searcher agents emulate a group of animals which interact with each other based on the biological laws of collective motion. The proposed method has been compared to other well-known optimization algorithms. The results show good performance of the proposed method when searching for a global optimum of several benchmark functions.


PLoS ONE ◽  
2016 ◽  
Vol 11 (3) ◽  
pp. e0151834 ◽  
Author(s):  
Miguel Duarte ◽  
Vasco Costa ◽  
Jorge Gomes ◽  
Tiago Rodrigues ◽  
Fernando Silva ◽  
...  
Keyword(s):  

2021 ◽  
Vol 24 (2) ◽  
pp. 216-222
Author(s):  
Anne Templeton

During the COVID-19 pandemic, organizers of crowd events must facilitate physical distancing in environments where attendees previously enjoyed being close with ingroup members, encourage accurate perception of health risks and close adherence to safety guidance, and stop expected normative behaviors that may now be unsafe. Research from crowd psychology demonstrates how group processes are integral to each of these issues. The COVID-19 pandemic, however, has created an extreme case environment in which to evaluate the collective findings from previous research and identify future research directions. This paper outlines how organizers of crowd events and researchers can work together to further develop our understanding of social connectedness in crowds, reasons for risk-taking behavior, and level of engagement in new collective behaviors. By working together to address these issues, practitioners and researchers can develop our understanding of crowd processes and improve safety at future crowd events.


2021 ◽  
Author(s):  
Xu Li ◽  
Tingting Xue ◽  
Yu Sun ◽  
Jingfang Fan ◽  
Hui Li ◽  
...  

Abstract Living systems are full of astonishing diversity and complexity of life. Despite differences in the length scales and cognitive abilities of these systems, collective motion of large groups of individuals can emerge. It is of great importance to seek for the fundamental principles of collective motion, such as phase transitions and their natures. Via an eigen microstate approach, we have found a discontinuous transition of density and a continuous transition of velocity in the Vicsek models of collective motion, which are identified by the finite-size scaling form of order-parameter. At strong noise, living systems behave like gas. With the decrease of noise, the interactions between the particles of a living system become stronger and make them come closer. The living system experiences then a discontinuous gas-liquid like transition of density. The even stronger interactions at smaller noise make the velocity directions of particles become ordered and there is a continuous phase transition of collective motion in addition.


2013 ◽  
Vol 30 (2) ◽  
pp. 77-102
Author(s):  
Mahmoud Dhaouadi

This paper claims that human beings are first of all Homo Culturus and only then Homo Politicus, Homo Sociologus, or Homo Oeconomicus. Human beings are distinguished from all other species by what I call human symbols (HS), namely, language, thought, religion, knowledge/science, myths, laws, and cultural values and norms. As such, they are central to the human identity of individuals, groups, and societies and therefore basic keys for understanding and explaining individual as well as collective behaviors in human societies. The theoretical framework/paradigm of Homo Culturus also helps to explain the phenomenon of the human mind in its various forms: the illiterate mind, the educated mind, and the highly intellectual minds of scientists and scholars such as Ibn Khaldun.


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