Self-organization Phenomena Research Articles

Self-organization dynamics of charge carrier concentration in semiconductors due to the charge injection

The purpose of this study is to investigate the phenomenon of self-organization of the dynamics of charge carriers in semiconductor structures. Investigate the basic model, give a numerical estimate for given parameters and propose its modification. Determine the dependence of the evaluation results on the control parameter. Consider the dynamics when the control parameter depends on time. Carry out theoretical analysis, numerical simulation and build graphs. Methods. In this paper, we investigate the possibilities and limitations of the basic model of generation-recombination dynamics in semiconductors, proposed earlier by other researchers. A modification of this model was proposed and considered. Results. Various types of charge carrier concentration dynamics are demonstrated.Theoretical analysis of the model was carried out. Numerical simulation has shown that for certain values of the control parameter, stable states are observed. Numerical estimates of the control parameter were obtained, phase portraits of the nonlinear equation were constructed, and the behavior of the dynamical system was considered when the control parameter is periodic. The extended model showed a qualitatively new behavior in comparison with the basic one. Conclusion. It is shown that charge dynamics in semiconductor structures can exhibit different behaviors. The patterns and estimates obtained are consistent with those obtained earlier. The results obtained can be verified experimentally and will be useful in the development of photo- and beta-voltaic devices.

Self-organization phenomena in cold atmospheric pressure plasma slit jet

The radio frequency plasma slit jet, which produces 150 mm wide streaming plasma outside the jet body, exhibits exciting self-organization phenomena that resemble the self-organized patterns of dielectric barrier discharge (DBD) filaments. Similarly, as in DBD, the filaments are surrounded by an inhibition zone that does not allow two filaments to come closer to each other. With fast camera imaging, we observed the filamentary character of the discharge in all the studied gas feeds (Ar, Ar/N2, and Ar/O2). Still, the visual appearance of the filaments in the plasma and their interaction with a dielectric surface depended significantly on the gas feed. As the breakdown voltage in pure Ar is relatively low compared to the applied one, new filaments form frequently. Such newly created filaments disrupted the characteristic inter-filament distance, forcing the system to rearrange. The frequent ignition and decay processes in Ar led to short filament lifetimes (0.020–0.035 s) and their high jitter speed (0.9–1.7 m s−1), as determined with an image processing custom code based on Gwyddion libraries. The number of filaments was lower in the Ar/O2 and Ar/N2 mixtures. It was attributed to a loss of energy in the excitation of rotational and vibrational levels and oxygen electronegativity. Since the probability of low-current side discharges transitioning into the full plasma filaments was limited in these gas mixtures, the self-organized pattern was seldom disrupted, leading to lesser movement and longer lifetimes. Unlike in Ar or Ar/O2, the constricted filaments in Ar/N2 were surrounded by diffuse plasma plumes, likely connected to the presence of long-lived nitrogen species. We demonstrated in the polypropylene treatment that the self-organization phenomena affected the treatment uniformity.

Stress anisotropy in confined populations of growing rods.

A central feature of living matter is its ability to grow and multiply. The mechanical activity associated with growth produces both macroscopic flows shaped by confinement, and striking self-organization phenomena, such as orientational order and alignment, which are particularly prominent in populations of rod-shaped bacteria due to their nematic properties. However, how active stresses, passive mechanical interactions and flow-induced effects interact to give rise to the observed global alignment patterns remains elusive. Here, we study in silico colonies of growing rod-shaped particles of different aspect ratios confined in channel-like geometries. A spatially resolved analysis of the stress tensor reveals a strong relationship between near-perfect alignment and an inversion of stress anisotropy for particles with large length-to-width ratios. We show that, in quantitative agreement with an asymptotic theory, strong alignment can lead to a decoupling of active and passive stresses parallel and perpendicular to the direction of growth, respectively. We demonstrate the robustness of these effects in a geometry that provides less restrictive confinement and introduces natural perturbations in alignment. Our results illustrate the complexity arising from the inherent coupling between nematic order and active stresses in growing active matter, which is modulated by geometric and configurational constraints due to confinement.

Plant water stress, not termite herbivory, causes Namibia’s fairy circles

The fairy circles of Namibia form a remarkable gap pattern in arid grassland along the Namib Desert. The origin of the fairy circles is subject to an ongoing debate. Solving the mystery of the fairy circles (FCs) requires the right timing in fieldwork after rainfall, as the newly appearing grasses complete their life cycle within only a few weeks. Here we followed the rains along the Namib between 2020 and 2022 and assessed the cause of the grass death within FCs at different time intervals after grass-triggering rainfall. To assess whether termite herbivory was the cause, we used grass excavations and observations on the roots and shoots. To test if edaphic differences may explain the grass death in FCs, we undertook infiltration measurements in 10 FC-hotspot regions. Finally, we used continuous soil-moisture measurements from the dry into the rainy seasons to examine how the newly emerging grasses affect the soil-water content in space and time. Generally, in study plots that received grass-triggering rainfall most recently, the roots of the dead grasses in FCs were in 100 % of the cases undamaged, root-shoot ratios were significantly greater, and the roots were as long or even longer as those of the surrounding matrix grasses outside of the FCs. This indicates that drought stress caused grasses in the FCs to invest resources into roots to reach the percolating water. The results also show that the cause of the grass death in fairy circles was not induced by termite herbivory. Also, we found no systematic differences in the rate of water infiltration between FCs and the matrix, hence the plant wilting cannot result from quicker percolation within FCs. However, the soil-moisture measurements indicate that the matrix grasses strongly depleted the upper soil water of the FCs after rainfall, which explains why most grasses cannot establish and quickly die in the FCs. The research shows that grass death in fairy circles occurs immediately after rainfall due to plant water stress but not due to termite activity. Our results conform with previous fieldwork, pattern analysis and theoretical modeling, suggesting that Namibia’s fairy circles are a self-organized vegetation phenomenon induced by ecohydrological feedbacks.

Effect of interaction network structure in a response threshold model

Task allocation is a characteristic feature of social insects. This phenomenon is self-organized by workers in a colony without central instructions. Workers perform the necessary tasks while communicating and determining their colony’s local situations or outside environments. They can also allocate the workload of the task to finish quickly. To explain the self-organized phenomenon, we develop a theoretical model that includes the local interaction mechanism among the workers. We extend the fixed response threshold model by introducing the interaction network among workers. The new model is called the interaction network response threshold model. This model analyzes the effects of the interaction network structure on the workload allocation mechanism using the Gini coefficient. We find that the network structure affects the information diffusion process, and the network features affect workload allocation. Our results indicate that communication among the workers in a colony is an essential system for workload allocation.

Self-organisation phenomena in pedestrian counter flows and its modelling

We implement avoidance and following behaviour in a force-based model (AFFM) to develop realistic simulations of pedestrian counter flows. Using this innovative approach, we summarise an accelerate-then-decelerate lateral movement mode for pedestrians that minimised their required effort to avoid collisions with oncoming pedestrians travelling in the opposite direction. Then, we use the transfer entropy (TE) method to determine the spontaneous following behaviour of pedestrians to align their motion with a leading pedestrian moving towards the same destination. We also introduce a new parameter, lane entropy, to measure the motion smoothness of pedestrians and explain the quantitative characteristics of the lane formation phenomenon. The performance of the proposed model is compared with that of two other force-based models in terms of their ability to replicate the experimentally observed pedestrian flow patterns in a mock corridor, as designed by Feliciani and Nishinari in 2016. The results show that the AFFM performs well at reproducing microscopic behaviours observed in the experiments while consistently presenting the empirically observed lane formation phenomenon with quantitatively self-organised features (e.g., the order parameter and lane entropy). The proposed model is an efficient tool for future applications that can realistically model pedestrian counter flows under varying conditions.

Development of a Controlled Injection Method Using Support Templates for the Production of Chemobrionic Materials.

Chemobrionics is a research field about the well-known self-organized inorganic structures. Numerous research works have focused on controlling their growth pattern and characteristic features. In the present study, a controlled injection method is proposed to produce more regular self-assembled chemobrionics compared to the standard direct injection technique. This method involves the injection of a metal salt solution into an agarose support template filled with an anionic solution. The obtained structures were studied by scanning electron microscopy, X-ray microtomography, X-ray photoelectron spectroscopy, Raman spectroscopy, Fourier-transform IR spectroscopy, and thermogravimetric analysis. Despite the complex mechanism and chemistry underlying the self-organization phenomena, the controlled injection method enabled the generation of regular standard chemobrionic structures with high experimental reproducibility. It provided the extraction of tubular structures from the reaction vessel without breakage, thus allowing comprehensive characterization. Furthermore, the morphological, chemical, and thermal features of these structures were highly correlated with the standard chemobrionics obtained in the direct injection method. The proposed controlled injection method holds great promise for understanding and controlling the properties of chemobrionics and related structures.

Self-Organization of the Retina during Eye Development, Retinal Regeneration In Vivo, and in Retinal 3D Organoids In Vitro.

Self-organization is a process that ensures histogenesis of the eye retina. This highly intricate phenomenon is not sufficiently studied due to its biological complexity and genetic heterogeneity. The review aims to summarize the existing central theories and ideas for a better understanding of retinal self-organization, as well as to address various practical problems of retinal biomedicine. The phenomenon of self-organization is discussed in the spatiotemporal context and illustrated by key findings during vertebrate retina development in vivo and retinal regeneration in amphibians in situ. Described also are histotypic 3D structures obtained from the disaggregated retinal progenitor cells of birds and retinal 3D organoids derived from the mouse and human pluripotent stem cells. The review highlights integral parts of retinal development in these conditions. On the cellular level, these include competence, differentiation, proliferation, apoptosis, cooperative movements, and migration. On the physical level, the focus is on the mechanical properties of cell- and cell layer-derived forces and on the molecular level on factors responsible for gene regulation, such as transcription factors, signaling molecules, and epigenetic changes. Finally, the self-organization phenomenon is discussed as a basis for the production of retinal organoids, a promising model for a wide range of basic scientific and medical applications.

New insights into spatio-temporal dynamics of irradiation defects rafting

The self-organization of irradiation defects has continuously attracted numerous experimental and theoretical attentions, due to its influence on the service performance of irradiated materials. This work developed the discrete dislocation dynamics method by considering the thermal fluctuations, in order to statistically clarify the contribution of elastic interactions and thermal fluctuations to the temporal and spatial dynamics of raft formation. On temporal scales, this work for the first time demonstrates the existence of power-law scaling of raft formation time, and its insensitivity to the thermal fluctuations, and loop size distribution. The power-law exponent is consistent with many other self-organized critical phenomena, such as earthquakes, sandpile sliding, and dislocation avalanches, etc. On spatial scales, the deviation between the normal direction of the raft habit plane and the Burgers vector of the irradiation-induced interstitial loops was carefully analyzed, which agrees well with the experimental results.

An extended queueing model based on vision and morality for crowd evacuation

As one of the most common self-organizing phenomena in social systems, queueing has been attracting a lot of interest. Understanding the local interaction mechanism in queueing behaviors is a critical issue in the field of crowd dynamics. However, most studies ignore the heuristic decision during queueing processes. Even less is known about the effect of queueing behaviors on the collective movement. Therefore, an extended social force queueing model is proposed, which is based on vision and morality. Guided by visual and moral information, the desired speed and direction are heuristically adjusted in the self-driven force. Numerical simulations indicate that our model constructs a more realistic and detailed framework for the interpretation of pedestrian queueing. This model successfully predicts the emergence of the “detours” phenomenon, which is beneficial for reducing crowd pressure. Furthermore, our model may provide guidance for crowd management in safety science and navigation in autonomous robots.

Emergence and Artificial Intelligence in the Performing Arts

Starting from a brief analysis of the validity and applicability as a cognitive tool of the concept of emergency in the examination of the theatrical phenomenon, we evaluate the aspects related to the radical novelty that emergence implies as a phenomenon of systemic self-organization. Thus, taking into account both the ostensible nature of theatrical process and emergency and their ambiguous nature, any theatre performance can be considered as characterized by emergency. At the same time, the unpredictability of emergence makes it difficult to establish which of the current trends of theatrical manifestation will be validated by the appearance of theatrical novelty. Obviously, the impact that information technology has in the field of performing arts seems to imply that novelty might come from this dimension of theatrical activity. However, even if we can note performances played by actroids or performances whose texts are created by robots, we should treat carefully the idea that emergence might occur from this direction. In fact, there is a similarity in reception between, for example, animation theatre and performances based on actroids. We can also notice a similarity between a text created with the means of artificial intelligence and the collage technique. That is why we ask ourselves if what Martin Scorsese observed, namely that some films that benefit from a substantial contribution of the film trick made with the help of computer technology can no longer be included in the concept of cinematography, does not have the same kind of impact in the performing arts. Thus, the emergence, in the performing arts, does not necessarily lead to the renewal of the system, but can also lead to the appearance of a parallel system, different from the existing one. It remains to be seen to what extent a performance can still be defined as a theatre performance when the spectator becomes a robot.

Self-ordering of individual photons in waveguide QED and Rydberg-atom arrays

The scattering between light and individual saturable quantum emitters can induce strong optical nonlinearities and correlations between individual light quanta. Typically, this leads to an effective attraction that can generate exotic bound states of photons, which form quantum mechanical precursors of optical solitons, as found in many optical media. Here, we study the propagation of light through an optical waveguide that is chirally coupled to three-level quantum emitters. We show that the additional laser-coupling to a third emitter state not only permits to control the properties of the bound state but can even eliminate it entirely. This makes it possible to turn an otherwise focussing nonlinearity into a repulsive photon-photon interaction. We demonstrate this emerging photon-photon repulsion by analysing the quantum dynamics of multiple photons in large emitter arrays and reveal a dynamical fragmentation of incident uncorrelated light fields and self-ordering into regular trains of single photons. These striking effects expand the rich physics of waveguide quantum electrodynamics into the domain of repulsive photons and establish a conceptually simple platform to explore optical self-organization phenomena at the quantum level. We discuss implementations of this setting in cold-atom experiments and propose a new approach based on arrays of mesoscopic Rydberg-atom ensembles.

THE ROLE OF RECURSION IN THE SELF-ORGANIZATION OF THINKING

The article deals with the problem of thinking in the context of modern ideas about self-organization and related phenomena. Attention is drawn to the need to take into account the phenomenon of recursion as a possible basis for the self-organization of human thinking. A description of recursion and recursive thinking from the theoretical positions of the works of N. Luhmann, N. Chomsky, M. Korbalis and others is offered. The specifics of self-organization of thinking on the basis of the theoretical approaches of constructivism and autopoiesis are considered. The manifestations of recursion at the level of thinking and communication are considered. The role of recursion in such manifestations of self-organization of thinking as operational closure, self-reference and reflexive loop is analyzed. The article offers an explanation of the implementation of operational isolation in mental activity through recursive work with information as a necessary initial condition for self-organization that increases the autonomy of the thinking system. Special importance is attached to self-reference and reflexive loop, which allows, through recursive comparison, to provide important properties of self-organization of complex systems associated with self-reproduction and self-regulation. Attention is drawn to the close relationship of operational closure, self-reference and reflexive loops, mediated recursive processes. The main functions performed by each of the phenomena under consideration in the self-organization of thinking are determined. Conclusions are drawn about the presence of three main properties of self-organization of thinking realized through recursion: autonomy of the thinking system, its reproduction and provision of positive feedback.

Mechanisms driving self-organization phenomena in random plasmonic metasurfaces under multipulse femtosecond laser exposure: a multitime scale study

Abstract Laser-induced transformations of plasmonic metasurfaces pave the way for controlling their anisotropic optical response with a micrometric resolution over large surfaces. Understanding the transient state of matter is crucial to optimize laser processing and reach specific optical properties. This article proposes an experimental and numerical study to follow and explain the diverse irreversible transformations encountered by a random plasmonic metasurface submitted to multiple femtosecond laser pulses at a high repetition rate. A pump-probe spectroscopic imaging setup records pulse after pulse, and with a nanosecond time resolution, the polarized transmission spectra of the plasmonic metasurface, submitted to 50,000 ultrashort laser pulses at 75 kHz. The measurements reveal different regimes, occurring in different ranges of accumulated pulse numbers, where successive self-organized embedded periodic nanostructures with very different periods are observed by post-mortem electron microscopy characterizations. Analyses are carried out; thanks to laser-induced temperature rise simulations and calculations of the mode effective indices that can be guided in the structure. The overall study provides a detailed insight into successive mechanisms leading to shape transformation and self-organization in the system, their respective predominance as a function of the laser-induced temperature relative to the melting temperature of metallic nanoparticles and their kinetics. The article also demonstrates the dependence of the self-organized period on the guided-mode effective index, which approaches a resonance due to system transformation. Such anisotropic plasmonic metasurfaces have a great potential for security printing or data storage, and better understanding their formation opens the way to smart optimization of their properties.

Microscopic Characteristics and Modelling of Pedestrian Inflow Process with Inactive Persons

Inflow and outflow processes are common phenomena in daily life. Many types of research have been conducted to study the features of the outflow process, especially in scenarios with a single room or a straight corridor. A few scholars have paid attention to the movement characteristics of pedestrian inflow. Further explorations are still under great demand. In this contribution, a set of pre-conducted experiments are used to analyze the characteristics of the pedestrian inflow process with inactive persons. In these experiments, inactive persons were required to randomly cease within the room, leading to intensive detour behavior of pedestrians. The characteristics are carefully investigated using gradient analysis and curl analysis. To mimic the aforementioned inflow process, static global field is constructed to heuristically navigate a social force based microscopic model. The proposed model can reproduce the self-organized phenomena in the experiments. Our work can help understand the field feature of the pedestrian inflow process with inactive persons. High chaos level areas can be marked out providing practical information for managers.

Lipid islands on liquid crystal shells

By inducing phase separation in lipid monolayers on liquid crystal (LC) shells---thin hollow spheres of LC with water inside and outside---we reveal a rich set of coupled two- and three-dimensional (2D and 3D) self-organization phenomena enabled by the dual closely spaced internal and external spherical LC-water interfaces. Spindle-shaped 2D islands of condensed lipid monolayer first form at the primary interface where lipids are deposited, later also at the initially unexposed secondary interface, because lipids transfer through the LC. The LCs' elastic response to the 3D deformation caused by islands moves them from thin to thick regions on the shell and creates an attraction between opposite-side islands, topologically separated by the LCs, until they stack in a sandwich-like manner. We propose that the phase separation may be used for studying liposome adsorption on soft hydrophobic substrates, and to create unconventional colloidal particles with programmed interactions.

Topological synchronization of chaotic systems

A chaotic dynamics is typically characterized by the emergence of strange attractors with their fractal or multifractal structure. On the other hand, chaotic synchronization is a unique emergent self-organization phenomenon in nature. Classically, synchronization was characterized in terms of macroscopic parameters, such as the spectrum of Lyapunov exponents. Recently, however, we attempted a microscopic description of synchronization, called topological synchronization, and showed that chaotic synchronization is, in fact, a continuous process that starts in low-density areas of the attractor. Here we analyze the relation between the two emergent phenomena by shifting the descriptive level of topological synchronization to account for the multifractal nature of the visited attractors. Namely, we measure the generalized dimension of the system and monitor how it changes while increasing the coupling strength. We show that during the gradual process of topological adjustment in phase space, the multifractal structures of each strange attractor of the two coupled oscillators continuously converge, taking a similar form, until complete topological synchronization ensues. According to our results, chaotic synchronization has a specific trait in various systems, from continuous systems and discrete maps to high dimensional systems: synchronization initiates from the sparse areas of the attractor, and it creates what we termed as the ‘zipper effect’, a distinctive pattern in the multifractal structure of the system that reveals the microscopic buildup of the synchronization process. Topological synchronization offers, therefore, a more detailed microscopic description of chaotic synchronization and reveals new information about the process even in cases of high mismatch parameters.

Specifics of Self-Organization of Student’s Educational Activity During the COVID-19 Pandemic

Education is one of the most severely impacted sectors by Covid-19. One of the problems in the context of the organization and implementation of distance learning is the readiness of students to self-organize their learning activities. The issue of self-organization has been the focus of this article. Analysis and generalization of various studies show that in the conditions of quarantine, the effectiveness of learning directly depends on the processes of self-organization. To activate the process of self-organization, the student should initiate the process of the activity itself, and then update personal priorities to achieve the goal according to value dominants, motives, meanings, and prospects. The basic psychological and pedagogical concepts of self-organization have been analyzed. The role of the self-organization of educational activity in the student's academic success has been discussed. It was proved that formed self-organization of educational activity is a system-forming characteristic of the individual, which determines the value readiness of a student for independent lifelong learning, provides a high level of adaptability in the conditions of social and economic changes, and the ability to develop new technologies and new models of social interaction and behavior. The analysis has provided key insights into phenomena of self-organization in general and student’s self-organization of educational activity in particular. Based on the study and the practical experience of the authors, the model of self-organization of independent work of students has been presented. It comprises seven main blocks: introductory; actualization of knowledge; reflexive; competencies; diagnostic-reflexive; programming; self-education.

Guiding Self-Assembly of Active Colloids by Temporal Modulation of Activity.

Self-organization phenomena in ensembles of self-propelled particles open pathways to the synthesis of new dynamic states not accessible by traditional equilibrium processes. The challenge is to develop a set of principles that facilitate the control and manipulation of emergent active states. Here, we report that dielectric rolling colloids energized by a pulsating electric field self-organize into alternating square lattices with a lattice constant controlled by the parameters of the field. We combine experiments and simulations to examine spatiotemporal properties of the emergent collective patterns and investigate the underlying dynamics of the self-organization.We reveal the resistance of the dynamic lattices to compression and expansion stresses leading to a hysteretic behavior of the lattice constant. The general mechanism of pattern synthesis and control in active ensembles via temporal modulation of activity can be applied to other active colloidal systems.

Formation and evolution of striation plasma in high-pressure argon glow discharge

The self-organized striation phenomenon in the positive column region of glow discharge plasma is a basic problem in gas discharge physics, which involves rich physics such as electron dynamics, transport process, discharge instability and nonlinear phenomenon. It is an important topic in basic physics and practical application. In this work an argon glow discharge striation plasma at high pressure is reported. The electrical, optical and ionization wave propagation characteristics of the striation plasma, and the evolution of the striation plasma with pressure and impurity gas are investigated experimentally. The generation and quenching mechanism of argon striation plasma are analyzed. The results show that the striation length is about 1.5 mm, and decreases with pressure increasing, and the velocity and frequency of the ionization wave are estimated at 1.87 m/s and 1.25 kHz, respectively. The measurement of optical emission spectrum shows that the generation of striation plasma is probably related to the argon metastable atoms. The stepwise ionization process caused by metastable atoms triggers off an ionization instability. The instability propagates in the form of ionization wave, which leads the plasma parameters to be modulated longitudinally, thus, forming an alternating bright and dark striation plasma. The adding of nitrogen can effectively quench metastable argon atoms and change the electron energy distribution function, which destroys the instability conditions of the plasma, therefore, the striation plasma disappears. This work provides a new insight into the understanding of the formation and annihilation mechanism of glow discharge striation plasma at high pressure.