Synchronization Phenomena in an Array of Population Dynamic Systems

1998 ◽  
Vol 01 (02n03) ◽  
pp. 181-202 ◽  
Author(s):  
D. E. Postnov ◽  
A. G. Balanov ◽  
E. Mosekilde
Keyword(s):  
Population Dynamic ◽  
Bacterial Population ◽  
Dynamic Models ◽  
Complex Dynamics ◽  
Autonomous Systems ◽  
Continuation Methods ◽  
Global Synchronization ◽  
Unidirectional Flow ◽  
A Chain ◽  
The Individual

The paper applies continuation methods to examine fundFigureamental features of the complex dynamics that can arise in a cascaded system of population dynamic models. The individual model describes a bacterial population interacting with a population of viruses that attack the cells and exploit their reproductive system for their own replication. Coupling between the subsystems is brought about through a unidirectional flow of primary resources. In this way the individual subsystem is modulated by the varying nutrient concentration in the overflow from the upstream habitat. Synchronization of a single subsystem to an external periodic forcing exhibits an unusual bifurcation structure with global bifurcations appearing already at the lowest forcing amplitudes. This peculiarity is also observed for autonomous systems of two and three coupled habitats. Finally, local and global synchronization phenomena are investigated for a chain of 20 coupled population pools.

scholarly journals The dynamical formation of ephemeral groups on networks and their effects on epidemics spreading

2022 ◽  
Vol 12 (1) ◽  
Author(s):  
Marco Cremonini ◽  
Samira Maghool
Keyword(s):  
Dynamic Models ◽  
Complex Dynamics ◽  
Null Model ◽  
Network Models ◽  
Microscopic Level ◽  
Future Research ◽  
Group Dynamic ◽  
Core Element ◽  
The Individual ◽  
Agent Group

AbstractIn network models of propagation processes, the individual, microscopic level perspective is the norm, with aggregations studied as possible outcomes. On the contrary, we adopted a mesoscale perspective with groups as the core element and in this sense we present a novel agent-group dynamic model of propagation in networks. In particular, we focus on ephemeral groups that dynamically form, create new links, and dissolve. The experiments simulated 160 model configurations and produced results describing cases of consecutive and non-consecutive dynamic grouping, bounded or unbounded in the number of repetitions. Results revealed the existence of complex dynamics and multiple behaviors. An efficiency metric is introduced to compare the different cases. A Null Model analysis disclosed a pattern in the difference between the group and random models, varying with the size of groups. Our findings indicate that a mesoscopic construct like the ephemeral group, based on assumptions about social behavior and absent any microscopic level change, could produce and describe complex propagation dynamics. A conclusion is that agent-group dynamic models may represent a powerful approach for modelers and a promising new direction for future research in models of coevolution between propagation and behavior in society.

PREPARING PUBLIC SERVANTS IN EUROPEAN COUNTRIES: ARCHETYPAL APPROACH

2018 ◽  
Vol 1 (14) ◽  
pp. 255-263
Author(s):  
Oleh Ivanovich Rohulskyi
Keyword(s):  
Public Administration ◽  
Public Service ◽  
Professional Training ◽  
European Countries ◽  
Anglo Saxon ◽  
Public Servants ◽  
German Model ◽  
Managerial Positions ◽  
A Chain ◽  
The Individual

The article describes the main components of the institutional framework of an archetypical approach to public administration. It is determined that the system of preparation of public servants is based on a chain of universal foundations of archetype, in particular, it is influenced by the principle of formation of personnel in the public service, formed on the basis of public opinion. Based on two basic principles relating to admission to public service, three basic models of training civil servants in the European country are defined: German. French and Anglo-Saxon. We analyze each of the models and define the archetypes that influenced their formation and development. The advantages of each model are determined, in particular, the benefits are: the German model of training managers is the balancing between the theoretical knowledge and practical skills that a public servant receives during training, but as a disadvantage one can distinguish the orientation of preparation for legal orientation, which limits the ability to hold managerial positions for many employees The French model of professional training of public servants should include a well-balanced understanding of tasks, namely: decentralization and territorial organization of public services, communication, support of territorial communities, in-depth knowledge and understanding of the need for cooperation with institutions of the European Commonwealth, high-quality human resource management and orientation towards environmentally friendly innovations, such a model of training of public servants is holistic, costly and effective; The Anglo-Saxon model of training of public servants is its orientation towards the implementation of the concept of public administration and the individual approach to employee training, taking into account all the specifics of its activities, providing for the formation of personnel capable of solving specific problems. It is concluded that today in most European countries dominated by mixed models that include elements of different models.

scholarly journals Host-pathogen Immune Feedbacks Can Explain Widely Divergent Outcomes from Similar Infections

2021 ◽  
Author(s):  
Stephen Ellner ◽  
Nicolas Buchon ◽  
Tobias Doerr ◽  
Brian P Lazzaro
Keyword(s):  
Bacterial Population ◽  
Dynamic Models ◽  
System Response ◽  
Chronic Infections ◽  
Host Immune Responses ◽  
Lethal Infection ◽  
Negative Feedbacks ◽  
Immune System Response ◽  
Natural Result ◽  
The Cost

A longstanding question in infection biology is why two very similar individuals, with very similar pathogen exposures, may have very different outcomes. Recent experiments have found that even isogenic \emph{Drosophila melanogaster} hosts, given identical inoculations of some bacterial pathogens at suitable doses, can experience very similar initial bacteria proliferation but then diverge to either a lethal infection or a sustained chronic infection with much lower pathogen load. We hypothesized that divergent infection outcomes are a natural result of mutual negative feedbacks between pathogens and the host immune response. Here we test this hypothesis \emph{in silico} by constructing process-based dynamic models for bacterial population growth,host immune induction, and the feedbacks between them, based on common mechanisms of immune system response. Mathematical analysis of a minimal conceptual model confirms our qualitative hypothesis that mutual negative feedbacks can magnify small differences among hosts into life-or-death differences in outcome. However, explaining observed features of chronic infections requires an extension of the model to include induced pathogen modifications that shield themselves from host immune responses at the cost of reduced proliferation rate. Our analysis thus generates new, testable predictions about the mechanisms underlying bimodal infection outcomes.

scholarly journals An MEG Study of Picture Naming

1998 ◽  
Vol 10 (5) ◽  
pp. 553-567 ◽  
Author(s):  
Willem J. M. Levelt ◽  
Peter Praamstra ◽  
Antje S. Meyer ◽  
Päivi Helenius ◽  
Riitta Salmelin
Keyword(s):  
Picture Naming ◽  
Time Windows ◽  
Naming Latency ◽  
Cortical Activation ◽  
Response Patterns ◽  
Phonological Encoding ◽  
A Chain ◽  
Wernicke’S Area ◽  
The Individual ◽  
The Right

The purpose of this study was to relate a psycholinguistic processing model of picture naming to the dynamics of cortical activation during picture naming. The activation was recorded from eight Dutch subjects with a whole-head neuromagnetometer. The processing model, based on extensive naming latency studies, is a stage model. In preparing a picture's name, the speaker performs a chain of specific operations. They are, in this order, computing the visual percept, activating an appropriate lexical concept, selecting the target word from the mental lexicon, phonological encoding, phonetic encoding, and initiation of articulation. The time windows for each of these operations are reasonably well known and could be related to the peak activity of dipole sources in the individual magnetic response patterns. The analyses showed a clear progression over these time windows from early occipital activation, via parietal and temporal to frontal activation. The major specific findings were that (1) a region in the left posterior temporal lobe, agreeing with the location of Wernicke's area, showed prominent activation starting about 200 msec after picture onset and peaking at about 350 msec, (i.e., within the stage of phonological encoding), and (2) a consistent activation was found in the right parietal cortex, peaking at about 230 msec after picture onset, thus preceding and partly overlapping with the left temporal response. An interpretation in terms of the management of visual attention is proposed.

From individual cognition to populational culture

2012 ◽  
Vol 35 (4) ◽  
pp. 245-262 ◽  
Author(s):  
Krist Vaesen
Keyword(s):  
Cognitive Ability ◽  
Population Dynamic ◽  
Cultural Evolution ◽  
Social Cognitive ◽  
Dynamic Models ◽  
Cumulative Culture ◽  
Individual Level ◽  
Full Explanation ◽  
Individual Cognition ◽  
Future Work

AbstractIn my response to the commentaries from a collection of esteemed researchers, I reassess and eventually find largely intact my claim that human tool use evidences higher social and non-social cognitive ability. Nonetheless, I concede that my examination of individual-level cognitive traits does not offer a full explanation of cumulative culture yet. For that, one needs to incorporate them into population-dynamic models of cultural evolution. I briefly describe my current and future work on this.

The ultrastructure of Methanothrix concilii, a mesophilic aceticlastic methanogen

1986 ◽  
Vol 32 (9) ◽  
pp. 703-710 ◽  
Author(s):  
Terry J. Beveridge ◽  
Girish B. Patel ◽  
Bob J. Harris ◽  
G. Dennis Sprott
Keyword(s):  
Cell Wall ◽  
Plasma Membrane ◽  
Circular Plates ◽  
A Cell ◽  
Granular Matrix ◽  
A Chain ◽  
The Individual

Methanothrix concilii strain GP6 consists of a chain of rod-shaped cells, ca. 2.5 μm in length and 0.8 μm in width, which are encased in a tubular proteinaceous sheath. The sheath is composed of annular hoops, ca. 8.0 nm wide and 9.0 nm thick, which are stacked together to form the tube. The ends of the sheath, and therefore the cell filament, are blocked by single, multilayered, 13.5 nm thick, circular plates, designated as "spacer plugs," which contain a series of concentric rings; these also separate the individual cells within each filament. Each cell is therefore bounded by a tubular section of sheath and two spacer plugs. Completely encapsulating each cell, and lying between the sheath and cell, is an amorphous granular matrix. Overlying the plasma membrane and surrounding each protoplast is a thin veil of material which resembles a cell wall, but which is unable to maintain the rod shape when cells are extruded from the sheath.

scholarly journals Deep Sequencing Reveals Highly Complex Dynamics of Human Cytomegalovirus Genotypes in Transplant Patients over Time

2010 ◽  
Vol 84 (14) ◽  
pp. 7195-7203 ◽  
Author(s):  
Irene Görzer ◽  
Christian Guelly ◽  
Slave Trajanoski ◽  
Elisabeth Puchhammer-Stöckl
Keyword(s):  
Human Cytomegalovirus ◽  
Lung Transplant ◽  
Complex Dynamics ◽  
Clinical Samples ◽  
Mixed Genotype ◽  
Transplant Patients ◽  
Highly Sensitive ◽  
The Individual ◽  
Changes Over Time ◽  
Over Time

ABSTRACT In lung transplant patients undergoing immunosuppression, more than one human cytomegalovirus (HCMV) genotype may emerge during follow-up, and this could be critical for the outcome of HCMV infection. Up to now, many cases of infection with multiple HCMV genotypes were probably overlooked due to the limitations of the current genotyping approaches. We have now analyzed mixed-genotype infections in 17 clinical samples from 9 lung transplant patients using the highly sensitive ultradeep-pyrosequencing (UDPS) technology. UDPS genotyping was performed at three variable HCMV genes, coding for glycoprotein N (gN), glycoprotein O (gO), and UL139. Simultaneous analysis of a mean of 10,430 sequence reads per amplicon allowed the relative amounts of distinct genotypes in the samples to be determined down to 0.1% to 1% abundance. Complex mixtures of up to six different HCMV genotypes per sample were observed. In all samples, no more than two major genotypes accounted for at least 88% of the HCMV DNA load, and these were often accompanied by up to four low-abundance genotypes at frequencies of 0.1% to 8.6%. No evidence for the emergence of new genotypes or sequence changes over time was observed. However, analysis of different samples withdrawn from the same patients at different time points revealed that the relative levels of replication of the individual HCMV genotypes changed within a mixed-genotype population upon reemergence of the virus. Our data show for the first time that, similar to what has been hypothesized for the murine model, HCMV reactivation in humans seems to occur stochastically.

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