scholarly journals An Entropic Gradient Structure in the Network Dynamics of a Slime Mold

Symmetry ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1385
Author(s):  
Vincenzo Bonifaci
Keyword(s):  
Relative Entropy ◽  
Replicator Dynamics ◽  
Slime Mold ◽  
The State ◽  
Global Minimizer ◽  
Information Theoretic ◽  
Informational Divergence ◽  
The Stability ◽  
The Cost ◽  
Over Time

The approach to equilibrium in certain dynamical systems can be usefully described in terms of information-theoretic functionals. Well-studied models of this kind are Markov processes, chemical reaction networks, and replicator dynamics, for all of which it can be proven, under suitable assumptions, that the relative entropy (informational divergence) of the state of the system with respect to an equilibrium is nonincreasing over time. This work reviews another recent result of this type, which emerged in the study of the network optimization dynamics of an acellular slime mold, Physarum polycephalum. In this setting, not only the relative entropy of the state is nonincreasing, but its evolution over time is crucial to the stability of the entire system, and the equilibrium towards which the dynamics is attracted proves to be a global minimizer of the cost of the network.

scholarly journals Brief communication: A fast vortex-based smearing correction for the actuator line

2020 ◽  
Vol 5 (1) ◽  
pp. 349-353 ◽  
Author(s):  
Alexander R. Meyer Forsting ◽  
Georg R. Pirrung ◽  
Néstor Ramos-García
Keyword(s):  
Computational Cost ◽  
Original Method ◽  
The Self ◽  
Original Formulation ◽  
Dynamic Correction ◽  
The Stability ◽  
The Cost ◽  
Aerodynamic Surfaces ◽  
Lifting Line ◽  
Over Time

Abstract. The actuator line is a lifting line representation of aerodynamic surfaces in computational fluid dynamics applications but with non-singular forces, which reduces the self-induced velocities at the line. The vortex-based correction by Meyer Forsting et al. (2019a) recovers this missing induction and thus the intended lifting line behaviour of the actuator line. However, its computational cost exceeds that of existing tip corrections and quickly grows with blade discretization. Here we present different methods for reducing its computational cost to the level of existing corrections without jeopardizing the stability or accuracy of the original method. The cost is reduced by at least 98 %, whereas the power is maximally affected by 0.8 % with respect to the original formulation. This accelerated smearing correction remains a dynamic correction by modelling the variation in trailed vorticity over time. The correction is openly available (Meyer Forsting et al., 2019b).

scholarly journals Second-order freeriding on antisocial punishment restores the effectiveness of prosocial punishment

2017 ◽  
Author(s):  
Attila Szolnoki ◽  
Matjaž Perc
Keyword(s):  
Public Goods ◽  
Synergistic Effects ◽  
Evolutionary Stability ◽  
Second Order ◽  
Public Goods Game ◽  
Microscopic Mechanism ◽  
Spatial Pattern Formation ◽  
The Stability ◽  
The Cost ◽  
Over Time

Economic experiments have shown that punishment can increase public goods game contributions over time. However, the effectiveness of punishment is challenged by second-order freeriding and antisocial punishment. The latter implies that non-cooperators punish cooperators, while the former implies unwillingness to shoulder the cost of punishment. Here we extend the theory of cooperation in the spatial public goods game by considering four competing strategies, which are traditional cooperators and defectors, as well as cooperators who punish defectors and defectors who punish cooperators. We show that if the synergistic effects are high enough to sustain cooperation based on network reciprocity alone, antisocial punishment does not deter public cooperation. Conversely, if synergistic effects are low and punishment is actively needed to sustain cooperation, antisocial punishment does act detrimental, but only if the cost-to-fine ratio is low. If the costs are relatively high, cooperation again dominates as a result of spatial pattern formation. Counterintuitively, defectors who do not punish cooperators, and are thus effectively second-order freeriding on antisocial punishment, form an active layer around punishing cooperators, which protects them against defectors that punish cooperators. A stable three-strategy phase that is sustained by the spontaneous emergence of cyclic dominance is also possible via the same route. The microscopic mechanism behind the reported evolutionary outcomes can be explained by the comparison of invasion rates that determine the stability of subsystem solutions. Our results reveal an unlikely evolutionary escape from adverse effects of antisocial punishment, and they provide a rationale for why second-order freeriding is not always an impediment to the evolutionary stability of punishment.

On the Robustness of Solution Strategy Classifications

2010 ◽  
Vol 31 (2) ◽  
pp. 68-73 ◽  
Author(s):  
María José Contreras ◽  
Víctor J. Rubio ◽  
Daniel Peña ◽  
José Santacreu
Keyword(s):  
Individual Differences ◽  
Study Strategies ◽  
Solution Strategy ◽  
Specific Test ◽  
Spatial Tasks ◽  
The Stability ◽  
Strategy Changes ◽  
Over Time

Individual differences in performance when solving spatial tasks can be partly explained by differences in the strategies used. Two main difficulties arise when studying such strategies: the identification of the strategy itself and the stability of the strategy over time. In the present study strategies were separated into three categories: segmented (analytic), holistic-feedback dependent, and holistic-planned, according to the procedure described by Peña, Contreras, Shih, and Santacreu (2008) . A group of individuals were evaluated twice on a 1-year test-retest basis. During the 1-year interval between tests, the participants were not able to prepare for the specific test used in this study or similar ones. It was found that 60% of the individuals kept the same strategy throughout the tests. When strategy changes did occur, they were usually due to a better strategy. These results prove the robustness of using strategy-based procedures for studying individual differences in spatial tasks.

On the Stability of Evaluative Conditioning Effects

2013 ◽  
Vol 44 (6) ◽  
pp. 380-389 ◽  
Author(s):  
Sabine Förderer ◽  
Christian Unkelbach
Keyword(s):  
Evaluative Conditioning ◽  
Indirect Measures ◽  
The Stability ◽  
Over Time

Evaluative conditioning (EC) refers to valence changes in neutral stimuli (CSs) through repeated pairing with liked or disliked stimuli (USs). The present study examined the stability of EC effects in the course of 1 week. We investigated how this stability depends on memory for US valence and US identity. We also investigated whether CSs evaluations occurring immediately after conditioning (i.e., evaluative consolidation) are necessary for stable EC effects. Participants showed stable EC effects on direct and indirect measures, independent of evaluations immediately after conditioning. EC effects depended on memory for US valence but not for US identity. And although memory decreased significantly over time, EC effects remained stable. These data suggest that evaluative consolidation is not necessary, and that conditioned preferences and attitudes might persist even when people do not remember the concrete source anymore.

The cost of homelessness: Assessing change over time

2003 ◽  
Author(s):  
M. Spano ◽  
P. Toro ◽  
M. Goldstein
Keyword(s):  
Change Over Time ◽  
The Cost ◽  
Over Time

Opponent Center-Surround Contrast: Colour to Grey Conversion

2020 ◽  
Vol 2020 (1) ◽  
pp. 105-108
Author(s):  
Ali Alsam
Keyword(s):  
Evolutionary Algorithms ◽  
Three Dimensional ◽  
The State ◽  
Colour Space ◽  
Vision Science ◽  
State Of Art ◽  
Over Time

Vision is the science that informs us about the biological and evolutionary algorithms that our eyes, opticnerves and brains have chosen over time to see. This article is an attempt to solve the problem of colour to grey conversion, by borrowing ideas from vision science. We introduce an algorithm that measures contrast along the opponent colour directions and use the results to combine a three dimensional colour space into a grey. The results indicate that the proposed algorithm competes with the state of art algorithms.

The Internet Trap

2018 ◽  
Author(s):  
Matthew Hindman
Keyword(s):  
The Internet ◽  
Net Neutrality ◽  
The Public ◽  
Attention Economy ◽  
Digital News ◽  
The Cost ◽  
Over Time

The Internet was supposed to fragment audiences and make media monopolies impossible. Instead, behemoths like Google and Facebook now dominate the time we spend online—and grab all the profits from the attention economy. This book explains how this happened. It sheds light on the stunning rise of the digital giants and the online struggles of nearly everyone else—and reveals what small players can do to survive in a game that is rigged against them. The book shows how seemingly tiny advantages in attracting users can snowball over time. The Internet has not reduced the cost of reaching audiences—it has merely shifted who pays and how. Challenging some of the most enduring myths of digital life, the book explains why the Internet is not the postindustrial technology that has been sold to the public, how it has become mathematically impossible for grad students in a garage to beat Google, and why net neutrality alone is no guarantee of an open Internet. It also explains why the challenges for local digital news outlets and other small players are worse than they appear and demonstrates what it really takes to grow a digital audience and stay alive in today's online economy. The book shows why, even on the Internet, there is still no such thing as a free audience.

Cracking national integration after the events (the Arab Spring) and its impact On regional stability

2019 ◽  
Vol 3 (6) ◽  
pp. 1
Author(s):  
Muhannad Al Janabi Al Janabi
Keyword(s):  
Arab Spring ◽  
The State ◽  
The Political ◽  
Prominent Feature ◽  
Regional Stability ◽  
National Integration ◽  
Arab Region ◽  
Political Media ◽  
The Stability ◽  
The Arab Spring

Since late 2010 and early 2011, the Arab region has witnessed mass protests in Tunisia, Egypt, Libya, Syria, Yemen, Iraq, Bahrain and other countries that have been referred to in the political, media and other literature as the Arab Spring. These movements have had a profound effect on the stability of the regimes Which took place against it, as leaders took off and contributed to radical reforms in party structures and public freedoms and the transfer of power, but it also contributed to the occurrence of many countries in an internal spiral, which led to the erosion of the state from the inside until it became a prominent feature of the Arab) as is the case in Syria, Libya, Yemen and Iraq.

PREREQUISITES FOR THE FORMATION OF A MECHANISM FOR STATE REGULATION OF SOCIAL GUARANTEES IN THE REGION

2017 ◽  
Author(s):  
Vitaly Lobas ◽  
◽  
Elena Petryaeva ◽  
Keyword(s):  
Social Protection ◽  
Well Being ◽  
State Regulation ◽  
The State ◽  
Point Of View ◽  
Periodic Review ◽  
Cost Of Living ◽  
Economic Relations ◽  
State Management ◽  
The Cost

The article deals with modern mechanisms for managing social protection of the population by the state and the private sector. From the point of view of forms of state regulation of the sphere of social protection, system indicators usually include the state and dynamics of growth in the standard of living of the population, material goods, services and social guarantees for the poorly provided segments of the population. The main indicator among the above is the state of the consumer market, as one of the main factors in the development of the state. Priority areas of public administration with the use of various forms of social security have been identified. It should be emphasized that, despite the legislative conflicts that exist today in Ukraine, mandatory indexation of the cost of living is established, which is associated with inflation. Various scientists note that although the definition of the cost of living index has a well-established methodology, there are quite a lot of regional features in the structure of consumption. All this is due to restrictions that are included in the consumer basket of goods and different levels of socio-economic development of regions. The analysis of the establishment and periodic review of the minimum consumer budgets of the subsistence minimum and wages of the working population and the need to form state insurance funds for unforeseen circumstances is carried out. Considering in this context the levers of state management of social guarantees of the population, we drew attention to the crisis periods that are associated with the market transformation of the regional economy. In these conditions, there is a need to develop and implement new mechanisms and clusters in the system of socio-economic relations. The components of the mechanisms ofstate regulation ofsocial guarantees of the population are proposed. The deepening of market relations in the process of reforming the system of social protection of the population should be aimed at social well-being.

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