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1
Almeida, Michael J. "Collective Rationality and Simple Utilitarian Theories". Dialogue 33, n. 3 (1994): 363–76. http://dx.doi.org/10.1017/s0012217300039019.
Abstract (sommario):
Much of recent moral philosophy has been concerned with the relation between individual rationality and individual obligation. Familiar gametheoretic analyses, in particular the Prisoner's Dilemma, at least suggest that unconstrained pursuit of rational self-interest leads to collective ill. The difficulty is nicely illustrated by comparing the preference-orderings of distinct individuals over the possible outcomes of their actions to their collective preference-ordering. Consider the following typical version of the Prisoner's Dilemma, where R2 and C2 represent respectively “R has confessed to the crime” and “C has confessed to the crime,” and Rl and Cl correspond to “It is not the case that R has confessed” and “It is not the case that C has confessed.”
2
Noto, Daisuke, e Hugo N. Ulloa. "Simple tracking of occluded self-propelled organisms". Measurement Science and Technology 35, n. 3 (28 dicembre 2023): 035705. http://dx.doi.org/10.1088/1361-6501/ad1813.
Abstract (sommario):
Abstract Deepening our understanding of animals’ collective motions represents a multidisciplinary goal. Yet, quantifying the motions of hundreds of animals in the laboratory and nature posits a fundamental challenge for digital image processing: How do we track each object out of the crowd while allowing them to move freely in a three-dimensional (3D) domain? Here, we present a simple tracking strategy to reconstruct 3D trajectories with the aid of a mirror, even if moving objects experience occlusion. We explain the method using synthetically generated datasets and apply it to measure collective motions of phototactic zooplankton, Daphnia magna, swimming in a lab-scale aquarium at intermediate Reynolds numbers, 1 < R e < 13 . The method enables measuring statistics of characteristic features of D. magna swarm, including sinking velocities and flapping frequencies. Beyond the lab-scale animal tracking, we foresee further implementations of the method to study wild animals freely behaving in 3D environments irrespective of their species.
3
Sumpter, D. J. T. "The principles of collective animal behaviour". Philosophical Transactions of the Royal Society B: Biological Sciences 361, n. 1465 (28 novembre 2005): 5–22. http://dx.doi.org/10.1098/rstb.2005.1733.
Abstract (sommario):
In recent years, the concept of self-organization has been used to understand collective behaviour of animals. The central tenet of self-organization is that simple repeated interactions between individuals can produce complex adaptive patterns at the level of the group. Inspiration comes from patterns seen in physical systems, such as spiralling chemical waves, which arise without complexity at the level of the individual units of which the system is composed. The suggestion is that biological structures such as termite mounds, ant trail networks and even human crowds can be explained in terms of repeated interactions between the animals and their environment, without invoking individual complexity. Here, I review cases in which the self-organization approach has been successful in explaining collective behaviour of animal groups and societies. Ant pheromone trail networks, aggregation of cockroaches, the applause of opera audiences and the migration of fish schools have all been accurately described in terms of individuals following simple sets of rules. Unlike the simple units composing physical systems, however, animals are themselves complex entities, and other examples of collective behaviour, such as honey bee foraging with its myriad of dance signals and behavioural cues, cannot be fully understood in terms of simple individuals alone. I argue that the key to understanding collective behaviour lies in identifying the principles of the behavioural algorithms followed by individual animals and of how information flows between the animals. These principles, such as positive feedback, response thresholds and individual integrity, are repeatedly observed in very different animal societies. The future of collective behaviour research lies in classifying these principles, establishing the properties they produce at a group level and asking why they have evolved in so many different and distinct natural systems. Ultimately, this research could inform not only our understanding of animal societies, but also the principles by which we organize our own society.
4
Engelking, Anna. "Simple Hardworking Christian Folks, or the Self-Image of Contemporary Belarusian Kolkhozniks". East European Politics and Societies: and Cultures 27, n. 2 (10 gennaio 2013): 260–79. http://dx.doi.org/10.1177/0888325412469663.
Abstract (sommario):
This article concerns the anthropological inquiry about collective identity of contemporary Belarusian kolkhozniks. The author had conducted her field research (1993-2011) in both west and east Belarus. Source materials consist of about seven hundred conversations with individuals overwhelmingly more than sixty years of age. By analyzing and interpreting their narrative, the author traced the implicit values, norms, rules, basic semiotic dichotomies, and distinctive attributes in search of an unbiased insight into the content, structure, and building process of collective identity of the subjects under study. She concludes that the dichotomies, constitutive for collective identity of kolkhozniks—“peasant” versus “lord,” “peasant” versus “Jew,” and “Christian” versus “Jew”—result in the self-definition of muzhik-kolkhoznik as a simple, hard-working man “from here” belonging to a “Christian nation.” Neither the nation nor motherland, state nor language, belongs to the principal values of this group, which are “working the land” and “faith in God.” As a result of the petrifaction of the old model of the serfdom manor by the Soviet kolkhoz system, in a Belarusian village we presently encounter one of the last European residuals of premodern mentality and social identity. The image of Belarusian kolkhozniks’ collective identity has little to do with the popular category of Homo sovieticus and with the common stereotype of the kolkhoz. The human subject of the author’s anthropological reflection shows up as a person dealing amazingly well with extremely difficult living conditions and the modern, vivid personification of the archaic Homo religiosus.
5
Flechsig, Holger, e Alexander S. Mikhailov. "Simple mechanics of protein machines". Journal of The Royal Society Interface 16, n. 155 (giugno 2019): 20190244. http://dx.doi.org/10.1098/rsif.2019.0244.
Abstract (sommario):
While belonging to the nanoscale, protein machines are so complex that tracing even a small fraction of their cycle requires weeks of calculations on supercomputers. Surprisingly, many aspects of their operation can be however already reproduced by using very simple mechanical models of elastic networks. The analysis suggests that, similar to other self-organized complex systems, functional collective dynamics in such proteins is effectively reduced to a low-dimensional attractive manifold.
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Rodríguez, Alejandro, e James A. Reggia. "Extending Self-Organizing Particle Systems to Problem Solving". Artificial Life 10, n. 4 (settembre 2004): 379–95. http://dx.doi.org/10.1162/1064546041766424.
Abstract (sommario):
Self-organizing particle systems consist of numerous autonomous, purely reflexive agents (“particles”) whose collective movements through space are determined primarily by local influences they exert upon one another. Inspired by biological phenomena (bird flocking, fish schooling, etc.), particle systems have been used not only for biological modeling, but also increasingly for applications requiring the simulation of collective movements such as computer-generated animation. In this research, we take some first steps in extending particle systems so that they not only move collectively, but also solve simple problems. This is done by giving the individual particles (agents) a rudimentary intelligence in the form of a very limited memory and a top-down, goal-directed control mechanism that, triggered by appropriate conditions, switches them between different behavioral states and thus different movement dynamics. Such enhanced particle systems are shown to be able to function effectively in performing simulated search-and-collect tasks. Further, computational experiments show that collectively moving agent teams are more effective than similar but independently moving ones in carrying out such tasks, and that agent teams of either type that split off members of the collective to protect previously acquired resources are most effective. This work shows that the reflexive agents of contemporary particle systems can readily be extended to support goal-directed problem solving while retaining their collective movement behaviors. These results may prove useful not only for future modeling of animal behavior, but also in computer animation, coordinated movement control in robotic teams, particle swarm optimization, and computer games.
7
ALEKSIEJUK, AGATA, JANUSZ A. HOŁYST e GUEORGI KOSSINETS. "SELF-ORGANIZED CRITICALITY IN A MODEL OF COLLECTIVE BANK BANKRUPTCIES". International Journal of Modern Physics C 13, n. 03 (marzo 2002): 333–41. http://dx.doi.org/10.1142/s0129183102003164.
Abstract (sommario):
The question we address here is of whether phenomena of collective bankruptcies are related to self-organized criticality. In order to answer it we propose a simple model of banking networks based on the random directed percolation. We study effects of one bank failure on the nucleation of contagion phase in a financial market. We recognize the power law distribution of contagion sizes in 3d- and 4d-networks as an indicator of SOC behavior. The SOC dynamics was not detected in 2d-lattices. The difference between 2d- and 3d- or 4d-systems is explained due to the percolation theory.
8
Otsuka, T., Y. Tsunoda, T. Togashi, N. Shimizu e T. Abe. "Single-particle states vs. collective modes: friends or enemies ?" EPJ Web of Conferences 178 (2018): 02003. http://dx.doi.org/10.1051/epjconf/201817802003.
Abstract (sommario):
The quantum self-organization is introduced as one of the major underlying mechanisms of the quantum many-body systems. In the case of atomic nuclei as an example, two types of the motion of nucleons, single-particle states and collective modes, dominate the structure of the nucleus. The collective mode arises as the balance between the effect of the mode-driving force (e.g., quadrupole force for the ellipsoidal deformation) and the resistance power against it. The single-particle energies are one of the sources to produce such resistance power: a coherent collective motion is more hindered by larger spacings between relevant single particle states. Thus, the single-particle state and the collective mode are “enemies” against each other. However, the nuclear forces are rich enough so as to enhance relevant collective mode by reducing the resistance power by changing single-particle energies for each eigenstate through monopole interactions. This will be verified with the concrete example taken from Zr isotopes. Thus, the quantum self-organization occurs: single-particle energies can be self-organized by (i) two quantum liquids, e.g., protons and neutrons, (ii) monopole interaction (to control resistance). In other words, atomic nuclei are not necessarily like simple rigid vases containing almost free nucleons, in contrast to the naïve Fermi liquid picture. Type II shell evolution is considered to be a simple visible case involving excitations across a (sub)magic gap. The quantum self-organization becomes more important in heavier nuclei where the number of active orbits and the number of active nucleons are larger.
9
MEHANDIA, VISHWAJEET, e PRABHU R. NOTT. "The collective dynamics of self-propelled particles". Journal of Fluid Mechanics 595 (8 gennaio 2008): 239–64. http://dx.doi.org/10.1017/s0022112007009184.
Abstract (sommario):
We propose a method for the dynamic simulation of a collection of self-propelled particles in a viscous Newtonian fluid. We restrict attention to particles whose size and velocity are small enough that the fluid motion is in the creeping flow regime. We propose a simple model for a self-propelled particle, and extended the Stokesian Dynamics method to conduct dynamic simulations of a collection of such particles. In our description, each particle is treated as a sphere with an orientation vector p, whose locomotion is driven by the action of a force dipole Sp of constant magnitude S0 at a point slightly displaced from its centre. To simplify the calculation, we place the dipole at the centre of the particle, and introduce a virtual propulsion force Fp to effect propulsion. The magnitude F0 of this force is proportional to S0. The directions of Sp and Fp are determined by p. In isolation, a self-propelled particle moves at a constant velocity u0p, with the speed u0 determined by S0. When it coexists with many such particles, its hydrodynamic interaction with the other particles alters its velocity and, more importantly, its orientation. As a result, the motion of the particle is chaotic. Our simulations are not restricted to low particle concentration, as we implement the full hydrodynamic interactions between the particles, but we restrict the motion of particles to two dimensions to reduce computation. We have studied the statistical properties of a suspension of self-propelled particles for a range of the particle concentration, quantified by the area fraction φa. We find several interesting features in the microstructure and statistics. We find that particles tend to swim in clusters wherein they are in close proximity. Consequently, incorporating the finite size of the particles and the near-field hydrodynamic interactions is of the essence. There is a continuous process of breakage and formation of the clusters. We find that the distributions of particle velocity at low and high φa are qualitatively different; it is close to the normal distribution at high φa, in agreement with experimental measurements. The motion of the particles is diffusive at long time, and the self-diffusivity decreases with increasing φa. The pair correlation function shows a large anisotropic build-up near contact, which decays rapidly with separation. There is also an anisotropic orientation correlation near contact, which decays more slowly with separation. Movies are available with the online version of the paper.
10
Papadopoulou, Marina, Hanno Hildenbrandt, Daniel W. E. Sankey, Steven J. Portugal e Charlotte K. Hemelrijk. "Self-organization of collective escape in pigeon flocks". PLOS Computational Biology 18, n. 1 (10 gennaio 2022): e1009772. http://dx.doi.org/10.1371/journal.pcbi.1009772.
Abstract (sommario):
Bird flocks under predation demonstrate complex patterns of collective escape. These patterns may emerge by self-organization from local interactions among group-members. Computational models have been shown to be valuable for identifying what behavioral rules may govern such interactions among individuals during collective motion. However, our knowledge of such rules for collective escape is limited by the lack of quantitative data on bird flocks under predation in the field. In the present study, we analyze the first GPS trajectories of pigeons in airborne flocks attacked by a robotic falcon in order to build a species-specific model of collective escape. We use our model to examine a recently identified distance-dependent pattern of collective behavior: the closer the prey is to the predator, the higher the frequency with which flock members turn away from it. We first extract from the empirical data of pigeon flocks the characteristics of their shape and internal structure (bearing angle and distance to nearest neighbors). Combining these with information on their coordination from the literature, we build an agent-based model adjusted to pigeons’ collective escape. We show that the pattern of turning away from the predator with increased frequency when the predator is closer arises without prey prioritizing escape when the predator is near. Instead, it emerges through self-organization from a behavioral rule to avoid the predator independently of their distance to it. During this self-organization process, we show how flock members increase their consensus over which direction to escape and turn collectively as the predator gets closer. Our results suggest that coordination among flock members, combined with simple escape rules, reduces the cognitive costs of tracking the predator while flocking. Such escape rules that are independent of the distance to the predator can now be investigated in other species. Our study showcases the important role of computational models in the interpretation of empirical findings of collective behavior.
11
Gloag, Erin S., Lynne Turnbull e Cynthia B. Whitchurch. "Bacterial Stigmergy: An Organising Principle of Multicellular Collective Behaviours of Bacteria". Scientifica 2015 (2015): 1–8. http://dx.doi.org/10.1155/2015/387342.
Abstract (sommario):
The self-organisation of collective behaviours often manifests as dramatic patterns of emergent large-scale order. This is true for relatively “simple” entities such as microbial communities and robot “swarms,” through to more complex self-organised systems such as those displayed by social insects, migrating herds, and many human activities. The principle of stigmergy describes those self-organised phenomena that emerge as a consequence of indirect communication between individuals of the group through the generation of persistent cues in the environment. Interestingly, despite numerous examples of multicellular behaviours of bacteria, the principle of stigmergy has yet to become an accepted theoretical framework that describes how bacterial collectives self-organise. Here we review some examples of multicellular bacterial behaviours in the context of stigmergy with the aim of bringing this powerful and elegant self-organisation principle to the attention of the microbial research community.
12
Bleibel, J., M. Habiger, M. Lütje, F. Hirschmann, F. Roosen-Runge, T. Seydel, F. Zhang, F. Schreiber e M. Oettel. "Two time scales for self and collective diffusion near the critical point in a simple patchy model for proteins with floating bonds". Soft Matter 14, n. 39 (2018): 8006–16. http://dx.doi.org/10.1039/c8sm00599k.
13
Yoshinaga, Natsuhiko. "Simple Models of Self-Propelled Colloids and Liquid Drops: From Individual Motion to Collective Behaviors". Journal of the Physical Society of Japan 86, n. 10 (15 ottobre 2017): 101009. http://dx.doi.org/10.7566/jpsj.86.101009.
14
Camazine, Scott, e James Sneyd. "A model of collective nectar source selection by honey bees: Self-organization through simple rules". Journal of Theoretical Biology 149, n. 4 (aprile 1991): 547–71. http://dx.doi.org/10.1016/s0022-5193(05)80098-0.
15
Heyde, Alexander, Lijie Guo, Christian Jost, Guy Theraulaz e L. Mahadevan. "Self-organized biotectonics of termite nests". Proceedings of the National Academy of Sciences 118, n. 5 (19 gennaio 2021): e2006985118. http://dx.doi.org/10.1073/pnas.2006985118.
Abstract (sommario):
The termite nest is one of the architectural wonders of the living world, built by the collective action of workers in a colony. Each nest has several characteristic structural motifs that allow for efficient ventilation, cooling, and traversal. We use tomography to quantify the nest architecture of the African termite Apicotermes lamani, consisting of regularly spaced floors connected by scattered linear and helicoidal ramps. To understand how these elaborate structures are built and arranged, we formulate a minimal model for the spatiotemporal evolution of three hydrodynamic fields—mud, termites, and pheromones—linking environmental physics to collective building behavior using simple local rules based on experimental observations. We find that floors and ramps emerge as solutions of the governing equations, with statistics consistent with observations of A. lamani nests. Our study demonstrates how a local self-reinforcing biotectonic scheme is capable of generating an architecture that is simultaneously adaptable and functional, and likely to be relevant for a range of other animal-built structures.
16
Knifsend, Casey A., Leigh A. Green e Kathryn L. Clifford. "Extracurricular Participation, Collective Self-Esteem, and Academic Outcomes Among College Students". Psi Chi Journal of Psychological Research 25, n. 4 (2020): 318–26. http://dx.doi.org/10.24839/2325-7342.jn25.4.318.
Abstract (sommario):
Participating in extracurricular activities during college has been linked with positive peer relations and academic success (e.g., Astin, 1984; Stuart et al., 2011). Yet, less research has focused on identity development and collective self-esteem within extracurricular activities, or whether such positive attitudes about one’s activity membership are associated with academic outcomes. In the current study, analyses focused primarily on those who were in at least one activity (n = 109), who reported on friendships within their activity, perceptions of interdependence among members, and collective self-esteem within their activity, as well as their feelings of belonging on campus and grade point average. Regression analyses suggested that having friends in one’s activity (β = .33, p = .001) and higher interdependence (β = .51, p < .001) predicted higher collective self-esteem, with a total adjusted R2 = .44. In turn, greater collective self-esteem was associated marginally with higher feelings of belonging (β = .20, p = .07, adjusted R2 = .07) and grade point average for those in fraternities or sororities (interaction β = .34, p = .006; adjusted R2 = .17; simple slope for Greek organizations: β = .42, p = .07). These findings underscore the importance of considering different dimensions of extracurricular involvement (i.e., both whether one is involved, as well as positive feelings about one’s activity), and provide recommendations to student affairs professionals as to how activities may be structured to promote optimal outcomes during college.
17
DE CARA, M. ÁNGELES R., ÓSCAR PLA e FRANCISCO GUINEA. "LEARNING, COMPETITION AND COOPERATION IN SIMPLE GAMES". International Journal of Theoretical and Applied Finance 03, n. 03 (luglio 2000): 463–64. http://dx.doi.org/10.1142/s0219024900000395.
Abstract (sommario):
The Minority Game was introduced to study the competition between agents with bounded rationality. As the amount of information available decreases, agents manage to arbitrage away all the information, and collective gain is then reduced. This crowd effect arises from the fact that only a minority can profit at each moment, while all agents make their choices using the same input. The properties of the model change drastically if agents make choices based on their individual histories, keeping all remaining rules unaltered. This variation reduces the intrinsic frustration of the model, and improves the tendency towards cooperation and self organization. Finally, we study the stable mixing of individual and cooperative behavior.
18
RODRÍGUEZ, ALEJANDRO, ALEXANDER GRUSHIN e JAMES A. REGGIA. "SWARM INTELLIGENCE SYSTEMS USING GUIDED SELF-ORGANIZATION FOR COLLECTIVE PROBLEM SOLVING". Advances in Complex Systems 10, supp01 (agosto 2007): 5–34. http://dx.doi.org/10.1142/s0219525907001069.
Abstract (sommario):
Drawing inspiration from social interactions in nature, the field of swarm intelligence has presented a promising approach to the design of complex systems consisting of numerous, usually homogeneous, simple parts, to solve a wide variety of problems. Like cellular automata, swarm-intelligence systems involve highly parallel computations across space, based heavily on self-organization, the emergence of global behavior through local interactions of components, and the absence of centralized or global control. However, this has a disadvantage as the desired behavior of a system becomes hard to predict or design based on its local interaction rules. In our ongoing research, we propose to provide greater control over a system, and potentially more useful, goal-oriented behavior, by introducing layered, hierarchical controllers in the particles or components. The layered controllers allow each particle to extend their reactive behavior in a more goal-oriented style, while keeping the locality of the interactions and the general simplicity of the system. In this paper, we present three systems designed using this approach: a competitive foraging system, a system for the collective transport and distribution of goods, and a self-assembly system capable of creating complex structures in a 3D world. Our simulation results show that in all three cases it was possible to guide the self-organization process at different levels of the designated task, suggesting that the self-organizing behavior of swarm-intelligence systems may be extendable to support problem solving in various contexts, such as coordinated robotic teams.
19
Turgut, Ali Emre, İhsan Caner Boz, İlkin Ege Okay, Eliseo Ferrante e Cristián Huepe. "Interaction network effects on position- and velocity-based models of collective motion". Journal of The Royal Society Interface 17, n. 169 (agosto 2020): 20200165. http://dx.doi.org/10.1098/rsif.2020.0165.
Abstract (sommario):
We study how the structure of the interaction network affects self-organized collective motion in two minimal models of self-propelled agents: the Vicsek model and the Active-Elastic (AE) model. We perform simulations with topologies that interpolate between a nearest-neighbour network and random networks with different degree distributions to analyse the relationship between the interaction topology and the resilience to noise of the ordered state. For the Vicsek case, we find that a higher fraction of random connections with homogeneous or power-law degree distribution increases the critical noise, and thus the resilience to noise, as expected due to small-world effects. Surprisingly, for the AE model, a higher fraction of random links with power-law degree distribution can decrease this resilience, despite most links being long-range. We explain this effect through a simple mechanical analogy, arguing that the larger presence of agents with few connections contributes localized low-energy modes that are easily excited by noise, thus hindering the collective dynamics. These results demonstrate the strong effects of the interaction topology on self-organization. Our work suggests potential roles of the interaction network structure in biological collective behaviour and could also help improve decentralized swarm robotics control and other distributed consensus systems.
20
Maggi, Giovanni, e Massimo Morelli. "Self-Enforcing Voting in International Organizations". American Economic Review 96, n. 4 (1 agosto 2006): 1137–58. http://dx.doi.org/10.1257/aer.96.4.1137.
Abstract (sommario):
Some international organizations are governed by unanimity rule, others by (simple or qualified) majority rules. Standard voting models, which assume that the decisions made by voting are perfectly enforceable, have a hard time explaining the observed variation in governance mode, and in particular the widespread occurrence of the unanimity system. We present a model whose main departure from standard voting models is that the organization cannot rely on external enforcement mechanisms: each country is sovereign and cannot be forced to comply with the collective decision or, in other words, the voting system must be self-enforcing. The model identifies conditions under which the organization adopts the unanimity rule, and yields rich comparative-statics predictions on the determinants of the mode of governance.
21
Hordijk, Wim, Mike Steel e Stuart Kauffman. "Autocatalytic Sets Arising in a Combinatorial Model of Chemical Evolution". Life 12, n. 11 (26 ottobre 2022): 1703. http://dx.doi.org/10.3390/life12111703.
Abstract (sommario):
The idea that chemical evolution led to the origin of life is not new, but still leaves open the question of how exactly it could have led to a coherent and self-reproducing collective of molecules. One possible answer to this question was proposed in the form of the emergence of an autocatalytic set: a collection of molecules that mutually catalyze each other’s formation and that is self-sustaining given some basic “food” source. Building on previous work, here we investigate in more detail when and how autocatalytic sets can arise in a simple model of chemical evolution based on the idea of combinatorial innovation with random catalysis assignments. We derive theoretical results, and compare them with computer simulations. These results could suggest a possible step towards the (or an) origin of life.
22
Sawada, Yasuyuki, Ryuji Kasahara, Keitaro Aoyagi, Masahiro Shoji e Mika Ueyama. "Modes of Collective Action in Village Economies: Evidence from Natural and Artefactual Field Experiments in a Developing Country". Asian Development Review 30, n. 1 (marzo 2013): 31–51. http://dx.doi.org/10.1162/adev_a_00002.
Abstract (sommario):
In a canonical model of collective action, individual contribution to collective action is negatively correlated with group size. Yet, empirical evidence on the group size effect has been mixed, partly due to heterogeneities in group activities. In this paper, we first construct a simple model of collective action with the free rider problem, altruism, public goods, and positive externalities of social networks. We then empirically test the theoretical implications of the group size effect on individual contribution to four different types of collective action, i.e., monetary or nonmonetary contribution to directly or indirectly productive activities. To achieve this, we collect and employ artefactual field experimental data such as public goods and dictator games conducted in southern Sri Lanka under a natural experimental situation where the majority of farmers were relocated to randomly selected communities based on the government lottery. This unique situation enables us to identify the causal effects of community size on collective action. We find that the levels of collective action can be explained by the social preferences of farmers. We also show evidence of free riding by self-interested households with no landholdings. The pattern of collective action, however, differs significantly by mode of activity—collective action that is directly rather than indirectly related to production is less likely to suffer from the free rider problem. Also, monetary contribution is less likely to cause free riding than nonmonetary labor contribution. Unlike labor contributions, monetary contributions involve collection of fees which can be easily tracked and verified, possibly leading to better enforcement of collective action.
23
Grigera, Tomás S. "Correlation functions as a tool to study collective behaviour phenomena in biological systems". Journal of Physics: Complexity 2, n. 4 (30 novembre 2021): 045016. http://dx.doi.org/10.1088/2632-072x/ac2b06.
Abstract (sommario):
Abstract Much of interesting complex biological behaviour arises from collective properties. Important information about collective behaviour lies in the time and space structure of fluctuations around average properties, and two-point correlation functions are a fundamental tool to study these fluctuations. We give a self-contained presentation of definitions and techniques for computation of correlation functions aimed at providing students and researchers outside the field of statistical physics a practical guide to calculating correlation functions from experimental and simulation data. We discuss some properties of correlations in critical systems, and the effect of finite system size, which is particularly relevant for most biological experimental systems. Finally we apply these to the case of the dynamical transition in a simple neuronal model.
24
MARCOZZI, ANDREA, e DAVID HALES. "EMERGENT SOCIAL RATIONALITY IN A PEER-TO-PEER SYSTEM". Advances in Complex Systems 11, n. 04 (agosto 2008): 581–95. http://dx.doi.org/10.1142/s0219525908001787.
Abstract (sommario):
Many peer-to-peer (P2P) applications require that nodes behave altruistically in order to perform tasks collectively. Here we examine a class of simple protocols that aim to self-organize P2P networks into clusters of altruistic nodes that help each other to complete jobs requiring diverse skills. We introduce a variant (called ResourceWorld) of an existing model (called SkillWorld) and compare results obtained in extensive (ten billion interactions) simulation experiments. It was found that for both model variants altruistic behavior was selected when certain cost/benefit constraints were met. Specifically, ResourceWorld selects for altruism only when the collective benefit of an action is at least as high as the individual cost. This gives a minimal method for realizing so-called "social rationality," where nodes select behaviors for the good of the collective even though actions are based on individual greedy utility maximization. Interestingly, the SkillWorld model evidences a kind of superaltruism in which nodes are prepared to cooperate even when the cost is higher than the benefit.
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Heinrich, Mary Katherine, Mohammad Divband Soorati, Tanja Katharina Kaiser, Mostafa Wahby e Heiko Hamann. "Swarm robotics: Robustness, scalability, and self-X features in industrial applications". it - Information Technology 61, n. 4 (27 agosto 2019): 159–67. http://dx.doi.org/10.1515/itit-2019-0003.
Abstract (sommario):
Abstract Applying principles of swarm intelligence to the control of autonomous systems in industry can advance our ability to manage complexity in prominent and high-cost sectors—such as transportation, logistics, and construction. In swarm robotics, the exclusive use of decentralized control relying on local communication and information provides the key advantage first of scalability, and second of robustness against failure points. These are directly useful in certain applied tasks that can be studied in laboratory environments, such as self-assembly and self-organized construction. In this article, we give a brief introduction to swarm robotics for a broad audience, with the intention of targeting future industrial applications. We then present a summary of four examples of our recently published research results with simple models. First, we present our approach to self-reconfiguration, which uses collective adjustment of swarm density in a dynamic setting. Second, we describe our robot experiments for self-organized material deployment in structured and semi-structured environments, applicable to braided composites. Third, we present our machine learning approach for self-assembly, motivated as a simple model developing foundational methods, which generates self-organizing robot behaviors to form emergent patterns. Fourth, we describe our experiments implementing a bioinspired model in a robot swarm, where we show self-healing of damage as the robots collectively locate a resource. Overall, the four examples we present concern robustness, scalability, and self-X features, which we propose as potentially relevant to future research in swarm robotics applied to industry sectors. We summarize these approaches as an introduction to our recent research, targeting the broad audience of this journal.
26
Murakami, Hisashi, Masato S. Abe e Yuta Nishiyama. "Toward Comparative Collective Behavior to Discover Fundamental Mechanisms Underlying Behavior in Human Crowds and Nonhuman Animal Groups". Journal of Robotics and Mechatronics 35, n. 4 (20 agosto 2023): 922–30. http://dx.doi.org/10.20965/jrm.2023.p0922.
Abstract (sommario):
This article provides comparative perspectives on collective behaviors that are widely found throughout the animal kingdom, ranging from insect and crustacea swarms, fish schools, bird flocks, and mammal herds to human crowds. Studies of nonhuman animal and human collective behaviors have progressed almost separately even though they have a similar history. Theoretical studies have investigated the reproduction of collective phenomena from simple inter-individual rules, and subsequent empirical and experimental studies have found diverse and complex collective behaviors that are difficult to explain with classical theoretical models. As a consequence, a wide variety of interaction rules have been proposed. To determine models to be implemented in nature and find fundamental mechanisms of collective behaviors, this paper argues that we should compare collective behaviors among various species while adopting Tinbergen’s four questions regarding mechanism, function, development, and evolution as a methodological basis. As an example of a comparative collective behavior paradigm, we introduce our studies in which a mutual anticipation mechanism inspired by nonhuman animal collective behaviors can be linked to a self-organization function in human collective behaviors. We expect that the study of comparative collective behaviors will expand, the methodology will become more sophisticated, and new perspectives regarding the multitemporal features of collective behaviors will emerge.
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Ali, Zain Anwar, Zhangang Han e Rana Javed Masood. "Collective Motion and Self-Organization of a Swarm of UAVs: A Cluster-Based Architecture". Sensors 21, n. 11 (31 maggio 2021): 3820. http://dx.doi.org/10.3390/s21113820.
Abstract (sommario):
This study proposes a collective motion and self-organization control of a swarm of 10 UAVs, which are divided into two clusters of five agents each. A cluster is a group of UAVs in a dedicated area and multiple clusters make a swarm. This paper designs the 3D model of the whole environment by applying graph theory. To address the aforesaid issues, this paper designs a hybrid meta-heuristic algorithm by merging the particle swarm optimization (PSO) with the multi-agent system (MAS). First, PSO only provides the best agents of a cluster. Afterward, MAS helps to assign the best agent as the leader of the nth cluster. Moreover, the leader can find the optimal path for each cluster. Initially, each cluster contains agents at random positions. Later, the clusters form a formation by implementing PSO with the MAS model. This helps in coordinating the agents inside the nth cluster. However, when two clusters combine and make a swarm in a dynamic environment, MAS alone is not able to fill the communication gap of n clusters. This study does it by applying the Vicsek-based MAS connectivity and synchronization model along with dynamic leader selection ability. Moreover, this research uses a B-spline curve based on simple waypoint defined graph theory to create the flying formations of each cluster and the swarm. Lastly, this article compares the designed algorithm with the NSGA-II model to show that the proposed model has better convergence and durability, both in the individual clusters and inside the greater swarm.
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Tyaningsih, Anisa Rara, Suryadi Suryadi e Desi Rahmawati. "Self-Efficacy, Teacher Leadership and Teacher Professionalism in Secondary School". Jurnal Iqra' : Kajian Ilmu Pendidikan 6, n. 2 (15 luglio 2021): 1–12. http://dx.doi.org/10.25217/ji.v6i2.1331.
Abstract (sommario):
The article was to determine the effect of self-efficacy on teacher professionalism, the effect of teacher leadership on teacher professionalism, and the effect of self-efficacy on teacher leadership. The research was conducted at 14 secondary school in West Jakarta, Indonesia by using survey method and testing the hypothesis with path analysis. Sample of this study consisted of 85 teachers selected by simple random sampling. The data collection technique was conducted by using an online questionnaire which was google form. The variable of self-efficacy includes learning strategies, class management, and student engagement. Then, the variable of teacher leadership includes four dimensions, namely collective leadership, leadership opportunity, leadership engagement, and supra-practitioner. Meanwhile, the teacher professionalism variable includes four domains, namely professional skills, autonomy in decision making, collaborative practice and commitment. The result shows that there was a positive direct effect of the self-efficacy variable on the teacher professionalism variable, there was a positive direct effect of the teacher leadership variable on the teacher professionalism variable and there was a positive direct effect of the self-efficacy variable on the teacher leadership variable. The result of the study was discussed by considering the relevant literature and implications were made.
Keywords: Teacher Leadership, Teacher Professionalism, Secondary School
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OBER, JOSIAH. "Democracy's Dignity". American Political Science Review 106, n. 4 (13 settembre 2012): 827–46. http://dx.doi.org/10.1017/s000305541200038x.
Abstract (sommario):
Dignity, as equal high standing characterized by nonhumiliation and noninfantilization, is democracy's third core value. Along with liberty and equality, it is a necessary condition for collective self-governance. Dignity enables robust exercise of liberty and equality while resisting both neglectful libertarianism and paternalistic egalitarianism. The civic dignity required for democracy is specified through a taxonomy of incompletely and fully moralized forms of dignity. Distinctive features of different regimes of dignity are modeled by simple games and illustrated by historical case studies. Unlike traditional meritocracy and universal human dignity, a civic dignity regime is theoretically stable in a population of self-interested social agents. It is real-world stable because citizens are predictably well motivated to defend those threatened with indignity and because they have resources for effective collective action against threats to dignity. Meritocracy and civic dignity are not inherently liberal, but may persist within a liberal democracy committed to universal human dignity.
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Karthika, T. "Women Empowerment through Self Help Group in Velappanadaroor at Sankarankovil Taluk". Shanlax International Journal of Commerce 7, n. 3 (1 luglio 2019): 90–94. http://dx.doi.org/10.34293/commerce.v7i3.537.
Abstract (sommario):
Self Help Groups are small voluntary associations of rural people, preferably womenfolk from the same socioeconomic background. They come together to solve common problems.The empowerment of women through Self Help Groups (SHGs) would lead to benefits not only to the individual women but also for the family and community as a whole through collective action for development. This paper is an attempt to analyze the women empowerment through self-help group. A simple random sampling technique is used to collect data. Both primary and secondary data were used. Fifty self-help group members’samples were collected through a structured questionnaire. Data were analyzed through statistical tools such as a percentage. This study concludes that the economic activities of the Self Help Group are quite successful. In this way Self Help Group in Sankarankovil Taluk Velappanadaroor area the very successful develop women empowerment and rural areas.
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Puckett, James G., e Nicholas T. Ouellette. "Determining asymptotically large population sizes in insect swarms". Journal of The Royal Society Interface 11, n. 99 (6 ottobre 2014): 20140710. http://dx.doi.org/10.1098/rsif.2014.0710.
Abstract (sommario):
Social animals commonly form aggregates that exhibit emergent collective behaviour, with group dynamics that are distinct from the behaviour of individuals. Simple models can qualitatively reproduce such behaviour, but only with large numbers of individuals. But how rapidly do the collective properties of animal aggregations in nature emerge with group size? Here, we study swarms of Chironomus riparius midges and measure how their statistical properties change as a function of the number of participating individuals. Once the swarms contain order 10 individuals, we find that all statistics saturate and the swarms enter an asymptotic regime. The influence of environmental cues on the swarm morphology decays on a similar scale. Our results provide a strong constraint on how rapidly swarm models must produce collective states. But our findings support the feasibility of using swarms as a design template for multi-agent systems, because self-organized states are possible even with few agents.
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Mracek, Maik, Tobias Hemsel, Piotr Vasiljev e Jörg Wallaschek. "Self Configuration of a Novel Miniature Ultrasonic Linear Motor". Solid State Phenomena 113 (giugno 2006): 167–72. http://dx.doi.org/10.4028/www.scientific.net/ssp.113.167.
Abstract (sommario):
Rotary ultrasonic motors have found broad industrial application in camera lens drives and other systems. Linear ultrasonic motors in contrast have only found limited applications. The main reason for the limited range of application of these very attractive devices seems to be their small force and power range. Attempts to build linear ultrasonic motors for high forces and high power applications have not been truly successful yet. To achieve drives, larger force and higher power, and multiple miniaturized motors can be combined. This approach, however, is not as simple as it appears at first glance. The electromechanical behavior of individual motors differs slightly due to manufacturing and assembly tolerances. Individual motor characteristics are strongly dependent on the driving parameters (frequency, voltage, temperature, pre-stress, etc.) and the driven load and the collective behavior of the swarm of motors is not just the linear superposition of the individual drive’s forces.
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Gautrais, Jacques, Christian Jost, Raphael Jeanson e Guy Theraulaz. "How individual interactions control aggregation patterns in gregarious arthropods". Interaction Studies 5, n. 2 (6 settembre 2004): 245–69. http://dx.doi.org/10.1075/is.5.2.05gau.
Abstract (sommario):
Aggregation is one of the most widespread phenomena in animal groups and often represents a collective dynamic response to environmental conditions. In social species the underlying mechanisms mostly obey self-organized principles. This phenomenon constitutes a powerful model to decouple purely social components from ecological factors. Here we used a model of cockroach aggregation to address the problems of sensitivity of collective patterns and control of aggregation dynamics. The individual behavioural rules (as a function of neighbour density) and the emergent collective patterns were previously quantified and modelled by Jeanson et al. (2003, 2004). We first present the diverse spatio-temporal patterns of a derived model in response to parameter changes, either involving social or non-social interactions. This sensitivity analysis is then extended to evaluate the evolution of these patterns in mixed societies of sub-populations with different behavioural parameters. Simple linear or highly non-linear collective responses emerge. We discuss their potential application to control animal populations by infiltration of biomimetic autonomous robots that mimic cockroach behaviour. We suggest that detailed behavioural models are a prerequisite to do so.
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Ong, Elvin. "Online Repression and Self-Censorship: Evidence from Southeast Asia". Government and Opposition 56, n. 1 (30 aprile 2019): 141–62. http://dx.doi.org/10.1017/gov.2019.18.
Abstract (sommario):
AbstractGovernments around the world have crafted new laws to threaten, arrest, prosecute and incarcerate online political activists. While the primary effect of online repression is to silence criticism and forestall collective action, a secondary effect is to induce self-censorship among the masses. Yet scant research examines how self-censorship works, nor discusses its implications for entrenching authoritarianism and encouraging democratic backsliding. This article proposes a simple expected utility model of self-censorship, arguing that citizens will more likely self-censor when the expected costs of online political expression outweigh its benefits. Analysing the fourth wave of the Asian Barometer survey of 10,216 respondents across eight Southeast Asian countries, I find that higher income politically engaged social media users are indeed less likely to express their political opinions. Additionally, this correlation holds in states where online repression is most severe, but is non-existent in countries where online repression is moderate or low.
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LESHANSKY, ALEXANDER M., JEFFREY F. MORRIS e JOHN F. BRADY. "Collective diffusion in sheared colloidal suspensions". Journal of Fluid Mechanics 597 (1 febbraio 2008): 305–41. http://dx.doi.org/10.1017/s0022112007009834.
Abstract (sommario):
Collective diffusivity in a suspension of rigid particles in steady linear viscous flows is evaluated by investigating the dynamics of the time correlation of long-wavelength density fluctuations. In the absence of hydrodynamic interactions between suspended particles in a dilute suspension of identical hard spheres, closed-form asymptotic expressions for the collective diffusivity are derived in the limits of low and high Péclet numbers, where the Péclet number ${\it Pe}\,{=}\,\gamdot a^2/D_0$ with $\gamdot$ being the shear rate and D0 = kBT/6πη a is the Stokes–Einstein diffusion coefficient of an isolated sphere of radius a in a fluid of viscosity η. The effect of hydrodynamic interactions is studied in the analytically tractable case of weakly sheared (Pe ≪ 1) suspensions.For strongly sheared suspensions, i.e. at high Pe, in the absence of hydrodynamics the collective diffusivity Dc = 6 Ds∞, where Ds∞ is the long-time self-diffusivity and both scale as $\phi \gamdot a^2$, where φ is the particle volume fraction. For weakly sheared suspensions it is shown that the leading dependence of collective diffusivity on the imposed flow is proportional to D0 φPeÊ, where Ê is the rate-of-strain tensor scaled by $\gamdot$, regardless of whether particles interact hydrodynamically. When hydrodynamic interactions are considered, however, correlations of hydrodynamic velocity fluctuations yield a weakly singular logarithmic dependence of the cross-gradient-diffusivity on k at leading order as ak → 0 with k being the wavenumber of the density fluctuation. The diagonal components of the collective diffusivity tensor, both with and without hydrodynamic interactions, are of O(φPe2), quadratic in the imposed flow, and finite at k = 0.At moderate particle volume fractions, 0.10 ≤ φ ≤ 0.35, Brownian Dynamics (BD) numerical simulations in which there are no hydrodynamic interactions are performed and the transverse collective diffusivity in simple shear flow is determined via time evolution of the dynamic structure factor. The BD simulation results compare well with the derived asymptotic estimates. A comparison of the high-Pe BD simulation results with available experimental data on collective diffusivity in non-Brownian sheared suspensions shows a good qualitative agreement, though hydrodynamic interactions prove to be important at moderate concentrations.
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Lutz, Matthew J., Chris R. Reid, Christopher J. Lustri, Albert B. Kao, Simon Garnier e Iain D. Couzin. "Individual error correction drives responsive self-assembly of army ant scaffolds". Proceedings of the National Academy of Sciences 118, n. 17 (23 aprile 2021): e2013741118. http://dx.doi.org/10.1073/pnas.2013741118.
Abstract (sommario):
An inherent strength of evolved collective systems is their ability to rapidly adapt to dynamic environmental conditions, offering resilience in the face of disruption. This is thought to arise when individual sensory inputs are filtered through local interactions, producing an adaptive response at the group level. To understand how simple rules encoded at the individual level can lead to the emergence of robust group-level (or distributed) control, we examined structures we call “scaffolds,” self-assembled by Eciton burchellii army ants on inclined surfaces that aid travel during foraging and migration. We conducted field experiments with wild E. burchellii colonies, manipulating the slope over which ants traversed, to examine the formation of scaffolds and their effects on foraging traffic. Our results show that scaffolds regularly form on inclined surfaces and that they reduce losses of foragers and prey, by reducing slipping and/or falling of ants, thus facilitating traffic flow. We describe the relative effects of environmental geometry and traffic on their growth and present a theoretical model to examine how the individual behaviors underlying scaffold formation drive group-level effects. Our model describes scaffold growth as a control response at the collective level that can emerge from individual error correction, requiring no complex communication among ants. We show that this model captures the dynamics observed in our experiments and is able to predict the growth—and final size—of scaffolds, and we show how the analytical solution allows for estimation of these dynamics.
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Giomi, L., N. Hawley-Weld e L. Mahadevan. "Swarming, swirling and stasis in sequestered bristle-bots". Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 469, n. 2151 (8 marzo 2013): 20120637. http://dx.doi.org/10.1098/rspa.2012.0637.
Abstract (sommario):
The collective ability of organisms to move coherently in space and time is ubiquitous in any group of autonomous agents that can move and sense each other and the environment. Here, we investigate the origin of collective motion and its loss using macroscopic self-propelled bristle-bots, simple automata made from a toothbrush and powered by an onboard cell phone vibrator-motor, that can sense each other through shape-dependent local interactions, and can also sense the environment non-locally via the effects of confinement and substrate topography. We show that when bristle-bots are confined to a limited arena with a soft boundary, increasing the density drives a transition from a disordered and uncoordinated motion to organized collective motion either as a swirling cluster or a collective dynamical stasis. This transition is regulated by a single parameter, the relative magnitude of spinning and walking in a single automaton. We explain this using quantitative experiments and simulations that emphasize the role of the agent shape, environment and confinement via boundaries. Our study shows how the behavioural repertoire of these physically interacting automatons controlled by one parameter translates into the mechanical intelligence of swarms.
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Shrivastava, Ashish K., e Dr Ajit Singh Patel. "Culture and Leadership in the Collective and Sustainable Growth of an Organization". International Journal of Management and Humanities 9, n. 9 (30 maggio 2023): 22–26. http://dx.doi.org/10.35940/ijmh.i1602.059923.
Abstract (sommario):
Fine art, classical music, and gourmet cuisine made "culture" aristocratic. City life became "culture" "civilization" (from lat. oivitas, city). Folktales helped Romantics see themselves as a "culture." "Low culture," the culture of social misfits, and "high culture" usually contrast. European culture developed in reaction to social inequalities in the late 18th and early 19th centuries. Europeans like Jean-Jacques Rousseau and Thomas Hobbes associated "culture" with "anarchy" and "nature." Native Americans, governed by Europeans since the 16th century, symbolised this contrast. Culture-advanced people and groups are hypothesised. Lewis's distinction may have affected Henry Morgan's cultural evolution theory and Herbert Spencer's social Darwinism. The split between high and low cultures has been attributed to the struggle between European colonial powers and European elites and non-elites. Leadership is visible and teachable, research shows. It's simple. Experience, constructive criticism, and chances may benefit potential leaders. Leaders grow via self-reflection, academics, experience, formal education, and training. You must recognise, grasp, and act on certain traits, concepts, and behaviours to encourage greater collaboration. Easy-to-learn skills are more useful. Leaders always improve. This paper will summarize the organizational culture and leader qualities and form a link in between.
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Ghaffarinejad, A., e F. Estilai. "Persian talismans and psychology". European Psychiatry 26, S2 (marzo 2011): 1054. http://dx.doi.org/10.1016/s0924-9338(11)72759-6.
Abstract (sommario):
Talisman is writing on metal, paper or animals skin which is a collection of diagrams, words, numbers and amazing patterns. Talismans usually are an illegible writings and not comprehensible for everyone.Talismans have had an important role in ordinary life and interpersonal relations of Iranians since the years.These talismans have used for making kindness, removing the evil eye effect, marriage, birth and…Despite, these are not studied scientifically and this question that talismans actually are archetype has no answer yet.Archetypes are a collection of perception and over perception which a group inherits. They are simple pictures and have dynamic process of collective unconscious.In this view, the talismans are a type of archetypes; they are natural process frequently repeat and have relation with inner and outer events of human's life.Major archetypes are Self, Shadow, Anima and Animus. In this article we try finding some of these archetypes in texts and pictures of ancient Iranian talismans base on Carl Gustav Jung psychology by using images and explain them.
40
Takada, K., Y. R. Shimizu e H. Thorn. "Application of the Dyson-type non-unitary representation of the self-consistent collective-coordinate method to simple models (I). SU(3) model". Nuclear Physics A 485, n. 2 (agosto 1988): 189–209. http://dx.doi.org/10.1016/0375-9474(88)90097-8.
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Thorn, H., Y. R. Shimizu e K. Takada. "Application of the Dyson-type non-unitary representation of the self-consistent collective-coordinate method to simple models (II). O(4) Model". Nuclear Physics A 486, n. 2 (settembre 1988): 221–34. http://dx.doi.org/10.1016/0375-9474(88)90231-x.
42
Posner, Eric A. "Human Rights, the Laws of War, and Reciprocity". Law & Ethics of Human Rights 6, n. 2 (17 gennaio 2013): 147–71. http://dx.doi.org/10.1515/1938-2545.1071.
Abstract (sommario):
Abstract Human rights law does not appear to enjoy as high a level of compliance as the laws of war, yet is institutionalized to a greater degree. This Article argues that the reason for this difference is related to the strategic structure of international law. The laws of war are governed by a regime of reciprocity, which can produce selfenforcing patterns of behavior, whereas the human rights regime attempts to produce public goods and is thus subject to collective action problems. The more elaborate human rights institutions are designed to overcome these problems but fall prey to second-order collective action problems. The simple laws of war institutions have been successful because they can exploit the logic of reciprocity. The Article also suggests that limits on military reprisals are in tension with self-enforcement of the laws of war. The U.S. conflict with Al Qaeda is discussed.
43
Chaté, Hugues. "Dry Aligning Dilute Active Matter". Annual Review of Condensed Matter Physics 11, n. 1 (10 marzo 2020): 189–212. http://dx.doi.org/10.1146/annurev-conmatphys-031119-050752.
Abstract (sommario):
Active matter physics is about systems in which energy is dissipated at some local level to produce work. This is a generic situation, particularly in the living world but not only. What is at stake is the understanding of the fascinating, sometimes counterintuitive, emerging phenomena observed, from collective motion in animal groups to in vitro dynamical self-organization of motor proteins and biofilaments. Dry aligning dilute active matter (DADAM) is a corner of the multidimensional, fast-growing domain of active matter that has both historical and theoretical importance for the entire field. This restrictive setting only involves self-propulsion/activity, alignment, and noise, yet unexpected collective properties can emerge from it. This review provides a personal but synthetic and coherent overview of DADAM, focusing on the collective-level phenomenology of simple active particle models representing basic classes of systems and on the solutions of the continuous hydrodynamic theories that can be derived from them. The obvious fact that orientational order is advected by the aligning active particles at play is shown to be at the root of the most striking properties of DADAM systems: ( a) direct transitions to orientational order are not observed; ( b) instead generic phase separation occurs with a coexistence phase involving inhomogeneous nonlinear structures; ( c) orientational order, which can be long range even in two dimensions, is accompanied by long-range correlations and anomalous fluctuations; ( d) defects are not point-like, topologically bound objects.
44
Chow, Chee W., F. Johnny Deng e Joanna L. Ho. "The Openness of Knowledge Sharing within Organizations: A Comparative Study of the United States and the People's Republic of China". Journal of Management Accounting Research 12, n. 1 (1 gennaio 2000): 65–95. http://dx.doi.org/10.2308/jmar.2000.12.1.65.
Abstract (sommario):
This study examines empirically the interaction effects of national culture and contextual factors (nature of the knowledge and the relationship between the knowledge sharer and recipient) on employees' tendency to share knowledge with co-workers. Quantitative and open-ended responses to two scenarios were collected from 142 managers (104 from the U.S. and 38 from the People's Republic of China). These two nations were selected due to their divergence on salient aspects of national culture, as well as their global political and economic importance. The focus on interaction effects was aimed at providing a more powerful test of culture's effects than simple comparisons of means typical of prior related research. Consistent with culture-based expectation, the quantitative results indicated that Chinese vs. U.S. nationals' openness of knowledge sharing was related to their different degrees of collectivism—the relative emphasis on self vs. collective interests—as well as whether knowledge sharing involved a conflict between self and collective interests. Also consistent with prediction, Chinese relative to U.S. nationals shared knowledge significantly less with a potential recipient who was not a member of their “ingroup.” Content analysis of the open-ended responses further showed that the quantitative results are the aggregated outcomes of trade-offs across cultural attributes and their interactions with contextual factors.
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Yalamova, Rossitsa. "Financial Engineering in Complex Dynamic Systems". Financial Engineering 1 (28 novembre 2023): 345–52. http://dx.doi.org/10.37394/232032.2023.1.32.
Abstract (sommario):
This paper explores the dynamic nature of financial markets through the lens of complex adaptive systems (CAS) theory, aiming to provide a comprehensive understanding of how financial markets deviate from the Efficient Market Hypothesis in extreme events such as bubbles and crashes. Traditional economic models often struggle to capture the intricate dynamics of 'self-organizing' financial markets, particularly the interaction between supply and demand in the face of evolving risks. CAS theory offers a promising framework for modeling asset prices, emphasizing the interconnectedness and adaptability of various agents within the system. The literature review highlights the significance of CAS theory in understanding the collective adaptation that emerges from interactions among heterogeneous agents. Notably, researchers such as Holland (1995) and Axelrod (1997) have demonstrated how simple agent-level rules can lead to sophisticated, self-organizing behaviors at the system level, resulting in more efficient outcomes. This paper also discusses the pivotal role of financial engineering in enhancing the adaptive capacity of socioeconomic systems under extreme stress. In an increasingly unpredictable world characterized by natural disasters, economic crises, and other unforeseen events, risk management serves as a vital mechanism for volatility mitigation and financial protection. By spreading risk collectively through hedging strategies, financial engineering not only provides portfolio security but also contributes to the resilience of financial and economic systems. By merging insights from CAS theory and the role of financial engineering in increasing adaptive capacity, this paper contributes to a more comprehensive understanding of the risk dynamics in financial markets impacting economic activities. Financial engineering tools mitigate negative shocks and reduce the severity of recessionary cycles. An attempt is made to explain how collective adaptation can lead to more efficient risk management and pricing, ultimately helping policymakers, fund managers, and researchers navigate the complexities of modern financial markets and fortify socioeconomic systems against extreme stressors.
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DECRAENE, JAMES, e BARRY MCMULLIN. "THE EVOLUTION OF COMPLEXITY IN SELF-MAINTAINING CELLULAR INFORMATION PROCESSING NETWORKS". Advances in Complex Systems 14, n. 01 (febbraio 2011): 55–75. http://dx.doi.org/10.1142/s0219525911002913.
Abstract (sommario):
We examine the role of self-maintenance (collective autocatalysis) in the evolution of computational biochemical networks. In primitive proto-cells (lacking separate genetic machinery) self-maintenance is a necessary condition for the direct reproduction and inheritance of what we here term Cellular Information Processing Networks (CIPNs). Indeed, partially reproduced or defective CIPNs may generally lead to malfunctioning or premature death of affected cells. We explore the interaction of this self-maintenance property with the evolution and adaptation of CIPNs capable of distinct information processing abilities. We present an evolutionary simulation platform capable of evolving artificial CIPNs from a bottom-up perspective. This system is an agent-based multi-level selectional Artificial Chemistry (AC) which employs a term rewriting system called the Molecular Classifier System (MCS.bl). The latter is derived from the Holland broadcast language formalism. Using this system, we successfully evolve an artificial CIPN to improve performance on a simple pre-specified information processing task whilst subject to the constraint of continuous self-maintenance. We also describe the evolution of self-maintaining, cross-talking and multi-tasking, CIPNs exhibiting a higher level of topological and functional complexity. This proof of concept aims at contributing to the understanding of the open-ended evolutionary growth of complexity in artificial systems.
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Baylis, James R., Ju Hun Yeon, Max H. Thomson, Amir Kazerooni, Xu Wang, Alex E. St. John, Esther B. Lim et al. "Self-propelled particles that transport cargo through flowing blood and halt hemorrhage". Science Advances 1, n. 9 (ottobre 2015): e1500379. http://dx.doi.org/10.1126/sciadv.1500379.
Abstract (sommario):
Delivering therapeutics deep into damaged tissue during bleeding is challenging because of the outward flow of blood. When coagulants cannot reach and clot blood at its source, uncontrolled bleeding can occur and increase surgical complications and fatalities. Self-propelling particles have been proposed as a strategy for transporting agents upstream through blood. Many nanoparticle and microparticle systems exhibiting autonomous or collective movement have been developed, but propulsion has not been used successfully in blood or used in vivo to transport therapeutics. We show that simple gas-generating microparticles consisting of carbonate and tranexamic acid traveled through aqueous solutions at velocities of up to 1.5 cm/s and delivered therapeutics millimeters into the vasculature of wounds. The particles transported themselves through a combination of lateral propulsion, buoyant rise, and convection. When loaded with active thrombin, these particles worked effectively as a hemostatic agent and halted severe hemorrhage in multiple animal models of intraoperative and traumatic bleeding. Many medical applications have been suggested for self-propelling particles, and the findings of this study show that the active self-fueled transport of particles can function in vivo to enhance drug delivery.
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Shaukat, Mansoor, e Mandar Chitre. "Adaptive behaviors in multi-agent source localization using passive sensing". Adaptive Behavior 24, n. 6 (20 settembre 2016): 446–63. http://dx.doi.org/10.1177/1059712316664120.
Abstract (sommario):
In this paper, the role of adaptive group cohesion in a cooperative multi-agent source localization problem is investigated. A distributed source localization algorithm is presented for a homogeneous team of simple agents. An agent uses a single sensor to sense the gradient and two sensors to sense its neighbors. The algorithm is a set of individualistic and social behaviors where the individualistic behavior is as simple as an agent keeping its previous heading and is not self-sufficient in localizing the source. Source localization is achieved as an emergent property through agent’s adaptive interactions with the neighbors and the environment. Given a single agent is incapable of localizing the source, maintaining team connectivity at all times is crucial. Two simple temporal sampling behaviors, intensity-based-adaptation and connectivity-based-adaptation, ensure an efficient localization strategy with minimal agent breakaways. The agent behaviors are simultaneously optimized using a two phase evolutionary optimization process. The optimized behaviors are estimated with analytical models and the resulting collective behavior is validated against the agent’s sensor and actuator noise, strong multi-path interference due to environment variability, initialization distance sensitivity and loss of source signal.
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Pearce, D. J. G., e M. S. Turner. "Emergent behavioural phenotypes of swarming models revealed by mimicking a frustrated anti-ferromagnet". Journal of The Royal Society Interface 12, n. 111 (ottobre 2015): 20150520. http://dx.doi.org/10.1098/rsif.2015.0520.
Abstract (sommario):
Self-propelled particle (SPP) models are often compared with animal swarms. However, the collective animal behaviour observed in experiments often leaves considerable unconstrained freedom in the structure of a proposed model. Essentially, multiple models can describe the observed behaviour of animal swarms in simple environments. To tackle this degeneracy, we study swarms of SPPs in non-trivial environments as a new approach to distinguish between candidate models. We restrict swarms of SPPs to circular (periodic) channels where they polarize in one of two directions (like spins) and permit information to pass through windows between neighbouring channels. Co-alignment between particles then couples the channels (anti-ferromagnetically) so that they tend to counter-rotate. We study channels arranged to mimic a geometrically frustrated anti-ferromagnet and show how the effects of this frustration allow us to better distinguish between SPP models. Similar experiments could therefore improve our understanding of collective motion in animals. Finally, we discuss how the spin analogy can be exploited to construct universal logic gates, and therefore swarming systems that can function as Turing machines.
50
Barrett, Scott. "Coordination vs. voluntarism and enforcement in sustaining international environmental cooperation". Proceedings of the National Academy of Sciences 113, n. 51 (7 novembre 2016): 14515–22. http://dx.doi.org/10.1073/pnas.1604989113.
Abstract (sommario):
The fates of “transboundary” environmental systems depend on how nation states interact with one another. In the absence of a hegemon willing and able to coerce other states into avoiding a “tragedy of the commons,” shared environments will be safeguarded if international cooperation succeeds and degraded or even destroyed if it fails. Treaties and related institutions of international law give form to these efforts to cooperate. Often, they implore states to act in their collective (as opposed to their national) interests. Sometimes, they impel cooperating states to punish free riders. A few agreements coordinate states’ behavior. Here, I present simple game-theoretic models showing whether and how treaties and related institutions can change incentives, aligning states’ self-interests with their collective interests. I show that, as a general matter, states struggle to cooperate voluntarily and enforce agreements to cooperate but that they find it relatively easy to coordinate actions. In some cases, the need for coordination is manifest. In other cases, it requires strategic thinking. Coordination may fall short of supporting an ideal outcome, but it nearly always works better than the alternatives.