scholarly journals Mathematical Framework for Breathing Chimera States

2022 ◽  
Vol 32 (2) ◽  
Author(s):  
O. E. Omel’chenko
Keyword(s):  
Coupled Oscillators ◽  
Analytic Solution ◽  
Coarse Grained ◽  
Mathematical Framework ◽  
Intensive Study ◽  
Phase Oscillators ◽  
Chimera States ◽  
The Subject ◽  
Self Consistency

AbstractAbout two decades ago it was discovered that systems of nonlocally coupled oscillators can exhibit unusual symmetry-breaking patterns composed of coherent and incoherent regions. Since then such patterns, called chimera states, have been the subject of intensive study but mostly in the stationary case when the coarse-grained system dynamics remains unchanged over time. Nonstationary coherence–incoherence patterns, in particular periodically breathing chimera states, were also reported, however not investigated systematically because of their complexity. In this paper we suggest a semi-analytic solution to the above problem providing a mathematical framework for the analysis of breathing chimera states in a ring of nonlocally coupled phase oscillators. Our approach relies on the consideration of an integro-differential equation describing the long-term coarse-grained dynamics of the oscillator system. For this equation we specify a class of solutions relevant to breathing chimera states. We derive a self-consistency equation for these solutions and carry out their stability analysis. We show that our approach correctly predicts macroscopic features of breathing chimera states. Moreover, we point out its potential application to other models which can be studied using the Ott–Antonsen reduction technique.

scholarly journals Cascades of Multiheaded Chimera States for Coupled Phase Oscillators

2014 ◽  
Vol 24 (08) ◽  
pp. 1440014 ◽  
Author(s):  
Yuri L. Maistrenko ◽  
Anna Vasylenko ◽  
Oleksandr Sudakov ◽  
Roman Levchenko ◽  
Volodymyr L. Maistrenko
Keyword(s):  
Periodic Orbit ◽  
Coupled Oscillators ◽  
Phase Oscillators ◽  
Invariant Circle ◽  
Saddle Node Bifurcation ◽  
Chimera States ◽  
Chimera State ◽  
Self Organized ◽  
Saddle Node ◽  
Different Types

Chimera state is a recently discovered dynamical phenomenon in arrays of nonlocally coupled oscillators, that displays a self-organized spatial pattern of coexisting coherence and incoherence. We discuss the appearance of the chimera states in networks of phase oscillators with attractive and with repulsive interactions, i.e. when the coupling respectively favors synchronization or works against it. By systematically analyzing the dependence of the spatiotemporal dynamics on the level of coupling attractivity/repulsivity and the range of coupling, we uncover that different types of chimera states exist in wide domains of the parameter space as cascades of the states with increasing number of intervals of irregularity, so-called chimera's heads. We report three scenarios for the chimera birth: (1) via saddle-node bifurcation on a resonant invariant circle, also known as SNIC or SNIPER, (2) via blue-sky catastrophe, when two periodic orbits, stable and saddle, approach each other creating a saddle-node periodic orbit, and (3) via homoclinic transition with complex multistable dynamics including an "eight-like" limit cycle resulting eventually in a chimera state.

scholarly journals A Demand - and Supply- Side Constrained Model for Liquidation Value and Related Exposure Periods

2018 ◽  
Vol 26 (2) ◽  
pp. 48-59 ◽  
Author(s):  
Vladimir B. Michaletz ◽  
Andrey Artemenkov
Keyword(s):  
Analytical Modeling ◽  
Analytic Solution ◽  
Supply Side ◽  
Eastern European ◽  
Demand And Supply ◽  
Market Values ◽  
Financial Interests ◽  
The Subject ◽  
Constrained Model

Abstract Two problems appear to be most topical in conjunction with mortgage valuation practices during an economic crisis: the assessment of sustainable long-term mortgage values and the assessment of liquidation discounts to prevailing market values which would provide for the most advantageous liquidation/quick sale strategy. This paper addresses the latter issue, which has traditionally proven intractable to analytical modeling. Apart from reviewing some research devoted to the subject of liquidation value modeling, predominantly from the Eastern European perspective, where this issue has, for years, commanded a particular economic interest, this paper synthesizes the best features of this research and builds on it to propose its own model, which lays equal emphasis on both the sellerside and demand-side perspectives. The first perspective accounts for the financial interests of a lender in forced sale disposals, while the latter perspective engages economic analysis on the side of market feasibility of identified efficient lender disposal strategies. By negotiating both perspectives, an optimal analytic solution to the issue of liquidation value discounts can be obtained. This is achieved by what we call a SI-MI framework which is developed throughout the paper. We also adapt this framework specifically to the mortgage banking context where we use it to bring to light some rarely discussed linkages between the LTV policies of a bank and its mortgage liquidation strategies. This also allows us to propose a model and an LTV formula which can help organize thinking about optimal LTV policies in credit issuing processes. We hope that, with the re-appearance of liquidation value basis/premise of valuation as a recognized international basis of valuation in the new edition of the International Valuation Standards (IVS 2017), the findings of this paper will become topical.

scholarly journals MODELLING INFILTRATION ON GRAVEL BEACHES WITH AN XBEACH VARIANT

2011 ◽  
Vol 1 (32) ◽  
pp. 41 ◽  
Author(s):  
Mohamad Hidayat Jamal ◽  
David J. Simmonds ◽  
Vanesa Magar ◽  
Shunqi Pan
Keyword(s):  
Sandy Beaches ◽  
Coarse Grained ◽  
Waves And Currents ◽  
Profile Changes ◽  
The Subject ◽  
Gravel Beaches ◽  
Sediment Transport Equation ◽  
The Uk ◽  
Sand And Gravel

Coarse-grained beaches are particularly prevalent in the UK, composed of accumulations of either gravel, or mixed sand and gravel sediments. Understanding and predicting their morphological behaviour in response to short-term and long-term forcing has been the subject of recent research. Despite the focus on sandy beaches, it is important to understand that the balance of processes that govern different behaviour between sandy and gravel beaches. In this study we show how a public domain numerical model, XBeach, developed for sandy environments (Roelvink et al., 2009) can be modified for use in predicting the cross-shore profile changes of gravel beaches. Improvements investigated here include: use of Lagrangian interpretation of velocity in place of Eulerian for driving sediment movement; incorporation of Packwood’s (1983) pragmatic model of infiltration in the unsaturated area of the swash region; introducing of new morphological module based upon Soulsby’s (1997) sediment transport equation for waves and currents. These changes are suggested in order to significantly improve the application of this model to gravel beaches, especially with regard to swash velocity asymmetry which is responsible for development of the steep accretionary phase steep berm above waterline. The results from the model agree well with the measured experimental data and improve upon the results presented by Pedrozo-Acuña et al. (2006).

Multi-headed loop chimera states in coupled oscillators

2021 ◽  
Vol 31 (1) ◽  
pp. 013135
Author(s):  
Dawid Dudkowski ◽  
Krzysztof Czołczyński ◽  
Tomasz Kapitaniak
Keyword(s):  
Coupled Oscillators ◽  
Chimera States

Expanding Foresight Evaluation Capacity

2019 ◽  
Vol 11 (4) ◽  
pp. 287-291
Author(s):  
Annette L. Gardner ◽  
Peter Bishop
Keyword(s):  
Decision Making ◽  
Professional Practice ◽  
Health Sector ◽  
Systematic Evaluation ◽  
Special Issue ◽  
Scenario Development ◽  
Evaluation Capacity ◽  
The Subject ◽  
Evaluation Approaches

The subject of evaluating foresight work has been around for almost as long as the professional practice itself has, but the field has done little to move closer to a systematic evaluation of its work. This special issue marks the second collection of articles on that project after a special issue of Futures in 2012 (Van Der Duin and Van Der Martin 2012). This issue takes a three-part approach: Part 1: evaluation of foresight in general and evaluation approaches and methods that can support designing an appropriate evaluation; Part 2: evaluation of foresight work in organizations and its impact on long-term thinking and decision-making; and Part 3: evaluation of specific foresight activities—an undergraduate learner foresight experience and a health sector scenario development exercise. The foreword ends with a reflection on the continuing issue of foresight and evaluation.

scholarly journals Non-breeding feather concentrations of testosterone, corticosterone and cortisol are associated with subsequent survival in wild house sparrows

2011 ◽  
Vol 279 (1733) ◽  
pp. 1560-1566 ◽  
Author(s):  
Lee Koren ◽  
Shinichi Nakagawa ◽  
Terry Burke ◽  
Kiran K. Soma ◽  
Katherine E. Wynne-Edwards ◽  
...  
Keyword(s):  
Stress Hormones ◽  
Passer Domesticus ◽  
House Sparrows ◽  
Long Term Study ◽  
Darwinian Fitness ◽  
Liquid Chromatography Tandem Mass ◽  
In The Wild ◽  
The Subject ◽  
As Stress

Potential mechanistic mediators of Darwinian fitness, such as stress hormones or sex hormones, have been the focus of many studies. An inverse relationship between fitness and stress or sex hormone concentrations has been widely assumed, although empirical evidence is scarce. Feathers gradually accumulate hormones during their growth and provide a novel way to measure hormone concentrations integrated over time. Using liquid chromatography–tandem mass spectrometry, we measured testosterone, corticosterone and cortisol in the feathers of house sparrows ( Passer domesticus ) in a wild population which is the subject of a long-term study. Although corticosterone is considered the dominant avian glucocorticoid, we unambiguously identified cortisol in feathers. In addition, we found that feathers grown during the post-nuptial moult in autumn contained testosterone, corticosterone and cortisol levels that were significantly higher in birds that subsequently died over the following winter than in birds that survived. Thus, feather steroids are candidate prospective biomarkers to predict the future survival of individuals in the wild.

The Long-Term Regulation of Safety Standards: The Case of the Electricity Industry in Australia and New Zealand

2012 ◽  
Vol 13 (4) ◽  
pp. 312-332
Author(s):  
Malcolm Abbott
Keyword(s):  
New Zealand ◽  
Electricity Industry ◽  
Political Context ◽  
Safety Standards ◽  
Safety Regulations ◽  
History Of ◽  
The Subject ◽  
Organizational Approach

Throughout much of the history of the electricity industry in Australia and New Zealand the industry has been the subject of safety regulations. Although this regulation has been a constant throughout the life of the industry the organizational approach to regulation has changed over the years. Periodically in Australia and New Zealand history these questions have been raised in a political context, although notably the structure of safety regulators does not get much attention in the standard histories of the industry. The purpose of this paper, therefore, is to discuss some of the general issues that have arisen in the reform of regulation in the case of electricity safety over the longer term and how it relates overall to the development of the electricity industry.

TWOFOLD IMPACT OF DELAYED FEEDBACK ON COUPLED OSCILLATORS

2007 ◽  
Vol 17 (07) ◽  
pp. 2517-2530 ◽  
Author(s):  
OLEKSANDR V. POPOVYCH ◽  
VALERII KRACHKOVSKYI ◽  
PETER A. TASS
Keyword(s):  
Time Delay ◽  
Coupling Strength ◽  
Coupled Oscillators ◽  
Phase Synchronization ◽  
Threshold Value ◽  
Phase Oscillators ◽  
Intermediate Coupling ◽  
Rich Variety ◽  
Dynamical Regimes ◽  
The Impact

We present a detailed bifurcation analysis of desynchronization transitions in a system of two coupled phase oscillators with delay. The coupling between the oscillators combines a delayed self-feedback of each oscillator with an instantaneous mutual interaction. The delayed self-feedback leads to a rich variety of dynamical regimes, ranging from phase-locked and periodically modulated synchronized states to chaotic phase synchronization and desynchronization. We show that an increase of the coupling strength between oscillators may lead to a loss of synchronization. Intriguingly, the delay has a twofold influence on the oscillations: synchronizing for small and intermediate coupling strength and desynchronizing if the coupling strength exceeds a certain threshold value. We show that the desynchronization transition has the form of a crisis bifurcation of a chaotic attractor of chaotic phase synchronization. This study contributes to a better understanding of the impact of time delay on interacting oscillators.

The Making of a Revolution in Tunisia

2011 ◽  
Vol 3 (1-2) ◽  
pp. 68-83 ◽  
Author(s):  
Laryssa Chomiak
Keyword(s):  
North Africa ◽  
Political Institutions ◽  
Political Repression ◽  
Political Liberalization ◽  
Political Activities ◽  
Authoritarian State ◽  
Short And Long Term ◽  
The Subject ◽  
Tunisian Revolution

In their search for explanations for the so-called Tunisian paradox under Ben Ali –a country with comparatively high levels of socio-economic development, yet plagued by the absence of a civil society that could push for political liberalization–analysts primarily investigated the gradual co-optation of political institutions and actors. As research and analytical agendas were consumed by the robustness of Ben Ali’s authoritarian state, little attention was paid to the development of informal and extra-institutional political activities that existed even under deepening political repression. In hindsight, many of these informal activities clearly contributed to the December 2010-January 2011 nation-wide campaign, which eventually led to the Arab World’s fi rst bottom-up revolution ousting an unpopular and illegitimate ruler. Th is article will engage two stories about the Tunisian Revolution that later inspired protests and contentious activities across the Middle East and North Africa. First, it will tell a back-story of contentious activities preceding the January 2011 events that surprised observers, scholars and analysts–even those familiar with the Tunisian case. Second, this article will discuss some of most pressing political dynamics that have emerged in the post-revolutionary (and pre-October 2011 election) environment. The concluding section will subsequently identify avenues for short and long-term research on the subject of contestation, resistance, and the construction of a new political order.

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