12,255 results match your criteria chaotic

[Results of optical coherence tomography angiography in choroidal melanoma].

A S Stoyukhina

Vestn Oftalmol 2021 ;137(2):18-25

Research Institute of Eye Diseases, Moscow, Russia.

Blood supply is known to be required for tumor growth and metastasis, and the formation of the tumor's own vasculature plays a critical role in the development of solid neoplasms. The method of optical coherence tomography angiography (OCTA) is considered promising for the study of angioarchitectonics.

Purpose: To evaluate the OCTA signs of choroidal melanoma (CM) depending on its sizes. Read More

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January 2021

Patterns of bacterial motility in microfluidics-confining environments.

Proc Natl Acad Sci U S A 2021 Apr;118(17)

Faculty of Engineering, Department of Bioengineering, McGill University, Montreal, QC H3A 0C3, Canada;

Understanding the motility behavior of bacteria in confining microenvironments, in which they search for available physical space and move in response to stimuli, is important for environmental, food industry, and biomedical applications. We studied the motility of five bacterial species with various sizes and flagellar architectures (, , , , and ) in microfluidic environments presenting various levels of confinement and geometrical complexity, in the absence of external flow and concentration gradients. When the confinement is moderate, such as in quasi-open spaces with only one limiting wall, and in wide channels, the motility behavior of bacteria with complex flagellar architectures approximately follows the hydrodynamics-based predictions developed for simple monotrichous bacteria. Read More

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Weak Feature Extraction and Strong Noise Suppression for SSVEP-EEG Based on Chaotic Detection Technology.

IEEE Trans Neural Syst Rehabil Eng 2021 Apr 19;PP. Epub 2021 Apr 19.

Brain computer interface (BCI) is a novel communication method that does not rely on the normal neural pathway between the brain and muscle of human. It can transform mental activities into relevant commands to control external equipment and establish direct communication pathway. Among different paradigms, steady-state visual evoked potential (SSVEP) is widely used due to its certain periodicity and stability of control. Read More

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Predicting the Patriarchal Politics of Pandemics From Mary Shelley to COVID-19.

Front Sociol 2021 24;6:624909. Epub 2021 Mar 24.

Department of Political Science, College of Arts and Letters, University of Notre Dame, Notre Dame, IN, United States.

I examine the predictive powers of the political science fictions of Mary Shelley, Octavia Butler, and Margaret Atwood for understanding the patriarchal-or men-dominant-dynamics of the politics of pandemics in the twenty-first century. Like her literary followers in post-apocalyptic plague literature, Butler and Atwood, Shelley foresaw that the twenty-first century would be the age of lethal pandemics. Their post-apocalyptic fictions also projected the ways that patriarchal and authoritarian forms of populism could shape the cultural circumstances that can turn a local outbreak of a new and deadly contagious disease, like COVID-19, into a politically chaotic and economically devastating global plague. Read More

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The Sovereign Ascendant: Financial Collapse, Status Anxiety, and the Rebirth of the Sovereign Citizen Movement.

Edwin Hodge

Front Sociol 2019 26;4:76. Epub 2019 Nov 26.

Department of Sociology, University of Victoria, Victoria, BC, Canada.

As many scholars have noted, periods of economic or social unrest often bring about the growth or resurgence of extremist social movements on both the political left and the right. The 1990s saw the rise of the American militia movement, largely in response to the emergence of international organizations like the North American Free Trade Agreement, the General Agreement on Tariffs and Trade, and an increasingly internationalist American administration. Earlier still, during the agricultural depression of the 1920s, the chaotic social, political, and economic order proved to be fertile ground for the resurgent Ku Klux Klan. Read More

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November 2019

Quantum chaos and the correspondence principle.

Phys Rev E 2021 Mar;103(3):L030201

Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China.

The correspondence principle is a cornerstone in the entire construction of quantum mechanics. This principle has been recently challenged by the observation of an early-time exponential increase of the out-of-time-ordered correlator (OTOC) in classically nonchaotic systems [E. B. Read More

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Self-organized criticality in neural networks from activity-based rewiring.

Phys Rev E 2021 Mar;103(3-1):032304

Institut für Theoretische Physik, Universität Bremen, Germany.

Neural systems process information in a dynamical regime between silence and chaotic dynamics. This has lead to the criticality hypothesis, which suggests that neural systems reach such a state by self-organizing toward the critical point of a dynamical phase transition. Here, we study a minimal neural network model that exhibits self-organized criticality in the presence of stochastic noise using a rewiring rule which only utilizes local information. Read More

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Transport of pseudothermal photons through an anharmonic cavity.

Sci Rep 2021 Apr 15;11(1):8328. Epub 2021 Apr 15.

Dukhov Research Institute of Automatics (VNIIA), Moscow, Russia, 127055.

Under nonequilibrium conditions, quantum optical systems reveal unusual properties that might be distinct from those in condensed matter. The fundamental reason is that photonic eigenstates can have arbitrary occupation numbers, whereas in electronic systems these are limited by the Pauli principle. Here, we address the steady-state transport of pseudothermal photons between two waveguides connected through a cavity with Bose-Hubbard interaction between photons. Read More

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Transportation as a barrier to colorectal cancer care.

BMC Health Serv Res 2021 Apr 13;21(1):332. Epub 2021 Apr 13.

Department of Population Health Sciences, Duke University School of Medicine, Durham, NC, 27701, USA.

Background: Transportation barriers limit access to cancer care services and contribute to suboptimal clinical outcomes. Our objectives were to describe the frequency of Veterans reporting and the factors associated with transportation barriers to or from colorectal cancer (CRC) care visits.

Methods: Between November 2015 and September 2016, Veterans with incident stage I, II, or III CRC completed a mailed survey to assess perceived barriers to recommended care. Read More

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Impacts of autapse on chaotic resonance in single neurons and small-world neuronal networks.

Philos Trans A Math Phys Eng Sci 2021 May 12;379(2198):20200237. Epub 2021 Apr 12.

Department of Biomedical Engineering, Zonguldak Bulent Ecevit University, 67100 Zonguldak, Turkey.

Chaotic resonance (CR) is a new phenomenon induced by an intermediate level of chaotic signal intensity in neuronal systems. In the current study, we investigated the effects of autapse on the CR phenomenon in single neurons and small-world (SW) neuronal networks. In single neurons, we assume that the neuron has only one autapse modelled as electrical, excitatory chemical and inhibitory chemical synapse, respectively. Read More

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Chaotic Dynamics on Air Quality and Human Health: Evidence from China, India, and Turkey.

Nonlinear Dynamics Psychol Life Sci 2021 Apr;25(2):207-236

Yildiz Technical University, Istanbul, Turkey.

The chaotic structure of air pollution, human health, the evidence of cointegration and causality between the air pollution, transportation, tourism, construction, and manufacturing industries and the evidence of cointegration and causality between the air pollution, transportation, tourism, construction, and manufacturing industries and mortality rate were explored for China, India, and Turkey in the period of 1975-2018 by using four different methods. Firstly, Lyapunov and Shannon tests were applied to determine chaotic dynamics. The maximum Lyapunov test, for the selected variables, found the evidence of chaotic dynamics. Read More

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Large-scale nonlinear Granger causality for inferring directed dependence from short multivariate time-series data.

Sci Rep 2021 Apr 9;11(1):7817. Epub 2021 Apr 9.

Department of Biomedical Engineering, University of Rochester, Rochester, New York, USA.

A key challenge to gaining insight into complex systems is inferring nonlinear causal directional relations from observational time-series data. Specifically, estimating causal relationships between interacting components in large systems with only short recordings over few temporal observations remains an important, yet unresolved problem. Here, we introduce large-scale nonlinear Granger causality (lsNGC) which facilitates conditional Granger causality between two multivariate time series conditioned on a large number of confounding time series with a small number of observations. Read More

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Synchronization of Chaotic Neural Networks: Average-Delay Impulsive Control.

IEEE Trans Neural Netw Learn Syst 2021 Apr 9;PP. Epub 2021 Apr 9.

In the brief, delayed impulsive control is investigated for the synchronization of chaotic neural networks. In order to overcome the difficulty that the delays in impulsive control input can be flexible, we utilize the concept of average impulsive delay (AID). To be specific, we relax the restriction on the upper/lower bound of such delays, which is not well addressed in most existing results. Read More

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Stablity based on PI control of three-dimensional chaotic oscillatory system via DNA chemical reaction networks.

IEEE Trans Nanobioscience 2021 Apr 9;PP. Epub 2021 Apr 9.

The classical proportional integral (PI) controller of SISO linear system is realized by DNA chemical reaction networks (CRNs) in the previous work. Up to now, few works have been done to realize PI controller of chaotic system through DNA CRNs. In this paper, a three-dimensional chaotic oscillatory system and a PI controller of three-dimensional chaotic oscillatory system are proposed by DNA CRNs. Read More

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Signatures of Chaos in Nonintegrable Models of Quantum Field Theories.

Phys Rev Lett 2021 Mar;126(12):121602

Faculty of Mathematics and Physics, University of Ljubljana, Ljubljana SI 1000, Slovenia.

We study signatures of quantum chaos in (1+1)D quantum field theory (QFT) models. Our analysis is based on the method of Hamiltonian truncation, a numerical approach for the construction of low-energy spectra and eigenstates of QFTs that can be considered as perturbations of exactly solvable models. We focus on the double sine-Gordon, also studying the massive sine-Gordon and ϕ^{4} model, all of which are nonintegrable and can be studied by this method with sufficiently high precision from small to intermediate perturbation strength. Read More

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Hydrodynamic Stabilization of Self-Organized Criticality in a Driven Rydberg Gas.

Phys Rev Lett 2021 Mar;126(12):123401

Department of Physics and Institute for Quantum Information and Matter, California Institute of Technology, Pasadena, California 91125, USA.

Signatures of self-organized criticality (SOC) have recently been observed in an ultracold atomic gas under continuous laser excitation to strongly interacting Rydberg states [S. Helmrich et al., Nature, 577, 481-486 (2020)]. Read More

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Multiple Morbidities in an Inner-City English Substance Misuse Treatment Service: Hierarchical Cluster Analysis to Derive Treatment Segments.

J Dual Diagn 2021 Apr 8:1-8. Epub 2021 Apr 8.

Statistical Services Centre, Reading, UK.

Objectives: Comorbid needs of people attending substance use treatment has been well documented although there is an assumption of heterogeneity in the treated population. This study utilized hierarchical cluster analysis to explore the extent and nature of client segments within the treated population. A retrospective review of comorbid health and social needs of a random sample of client case-notes ( = 300) was undertaken on all people known to treatment in an urban, inner-London community out-patient treatment service during 2018-2019. Read More

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Batman or Joker? A mixed-method approach to understanding children's perceptions of dentists.

Burak Buldur

Eur J Oral Sci 2021 Apr 7:e12787. Epub 2021 Apr 7.

Department of Pediatric Dentistry, Faculty of Dentistry, Sivas Cumhuriyet University, Sivas, Turkey.

It is important to understand children's perceptions of dentists in order to improve child-dentist communication. The aim of this mixed-methods study was to develop and validate a conceptual model of individual determinants of children's perceptions of dentists. A total of 1014 children completed an oral health behaviour form, a metaphor form, the Children's Fear Survey Schedule-Dental Subscale, the Dental Trust Scale, and the Early Childhood Oral Health Impact Scale. Read More

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Signature of Universal Fast Scrambling in the Transient Response of a Driven Mott Insulator System.

J Phys Condens Matter 2021 Apr 7. Epub 2021 Apr 7.

Department of Theoretical Physics, TIFR, Homi Bhabha Road, Navy Nagar, Mumbai, Maharashtra, 400005, INDIA.

The scrambling rate λa measure of the early growth of decoherence in an interacting quantum system, has been conjectured to have a universal saturation bound, λ≤ 2πkT/ℏ, where T is the temperature. This decoherence arises from the spread of quantum information over a large number of untracked degrees of freedom. The commonly studied indicator of scrambling is the out of time-ordered correlator (OTOC) of noncommuting quantum operators, in-turn related to generalized uncertainty relations, and reminiscent of the Lyapunov exponent of classically chaotic systems. Read More

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Improving mealtimes for patients and staff within an eating disorder unit: understanding of the problem and first intervention during the pandemic-an initial report.

BMJ Open Qual 2021 04;10(2)

Safety and Quality Improvement, Oxford Health NHS Foundation Trust, Oxford, UK.

Background: Mealtimes occur six times a day on eating disorder (ED) inpatient units and are a mainstay of treatment for EDs. However, these are often distressing and anxiety provoking times for patients and staff. A product of patients' distress is an increase in ED behaviours specific to mealtimes. Read More

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DCS-ELM: a novel method for extreme learning machine for regression problems and a new approach for the SFRSCC.

PeerJ Comput Sci 2021 12;7:e411. Epub 2021 Mar 12.

Firat University, Elazig, Turkey.

Extreme learning machine (ELM) algorithm is widely used in regression and classification problems due to its advantages such as speed and high-performance rate. Different artificial intelligence-based optimization methods and chaotic systems have been proposed for the development of the ELM. However, a generalized solution method and success rate at the desired level could not be obtained. Read More

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An efficient multi-factor authentication scheme based CNNs for securing ATMs over cognitive-IoT.

PeerJ Comput Sci 2021 2;7:e381. Epub 2021 Mar 2.

Department of Computer Science and Engineering, Faculty of Electronic Engineering, Menouf, Menoufia, Egypt.

Nowadays, the identity verification of banks' clients at Automatic Teller Machines (ATMs) is a very critical task. Clients' money, data, and crucial information need to be highly protected. The classical ATM verification method using a combination of credit card and password has a lot of drawbacks like Burglary, robbery, expiration, and even sudden loss. Read More

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Steganography in color images with random order of pixel selection and encrypted text message embedding.

PeerJ Comput Sci 2021 28;7:e380. Epub 2021 Jan 28.

Department of Computer Systems and Technologies, Faculty of Mathematics and Computer Science, Konstantin Preslavsky University of Shumen, Shumen, Shumen, Bulgaria.

Information security is major concern in modern digital ages, and the outdated algorithms need to be replaced with new ones or to be improved. In this article a new approach for hiding secret text message in color images is presented, combining steganography and cryptography. The location and the order of the image pixels chosen for information embedding are randomly selected using chaotic pseudo-random generator. Read More

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January 2021

Clinical Interpretation of Cardiopulmonary Exercise Testing: Current Pitfalls and Limitations.

Front Physiol 2021 18;12:552000. Epub 2021 Mar 18.

Laboratory of Clinical Exercise Physiology and Respiratory Investigation Unit, Queen's University and Kingston General Hospital, Kingston, ON, Canada.

Several shortcomings on cardiopulmonary exercise testing (CPET) interpretation have shed a negative light on the test as a clinically useful tool. For instance, the reader should recognize patterns of dysfunction based on clusters of variables rather than relying on rigid interpretative algorithms. Correct display of key graphical data is of foremost relevance: prolixity and redundancy should be avoided. Read More

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Real-time transition dynamics and stability of chip-scale dispersion-managed frequency microcombs.

Light Sci Appl 2020 Apr 3;9(1):52. Epub 2020 Apr 3.

Fang Lu Mesoscopic Optics and Quantum Electronics Laboratory, University of California, Los Angeles, CA, 90095, USA.

Femtosecond mode-locked laser frequency combs have served as the cornerstone in precision spectroscopy, all-optical atomic clocks, and measurements of ultrafast dynamics. Recently frequency microcombs based on nonlinear microresonators have been examined, exhibiting remarkable precision approaching that of laser frequency combs, on a solid-state chip-scale platform and from a fundamentally different physical origin. Despite recent successes, to date, the real-time dynamical origins and high-power stabilities of such frequency microcombs have not been fully addressed. Read More

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Revisiting the memory capacity in reservoir computing of directed acyclic network.

Chaos 2021 Mar;31(3):033106

Complex Systems Group, Department of Mathematics and Statistics, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia.

Reservoir computing (RC) is an attractive area of research by virtue of its potential for hardware implementation and low training cost. An intriguing research direction in this field is to interpret the underlying dynamics of an RC model by analyzing its short-term memory property, which can be quantified by the global index: memory capacity (MC). In this paper, the global MC of the RC whose reservoir network is specified as a directed acyclic network (DAN) is examined, and first we give that its global MC is theoretically bounded by the length of the longest path of the reservoir DAN. Read More

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Diffusion-induced regular and chaotic patterns in a ratio-dependent predator-prey model with fear factor and prey refuge.

Chaos 2021 Mar;31(3):033128

Centre for Mathematical Biology and Ecology, Department of Mathematics, Jadavpur University, Kolkata 700032, India.

Population distribution of interacting species in a large scale natural system is heterogeneous and subject to change for various reasons. Here, we explore how behavioral modification in prey species due to fear of predator and mutual interference between predators can create different spatiotemporal patterns in population distribution. We show that the fear factor and diffusion in a ratio-dependent predator-prey model may show more complex dynamics than observed earlier. Read More

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Symbolic partition in chaotic maps.

Chaos 2021 Mar;31(3):033144

School of Science, Beijing University of Posts and Telecommunications, Beijing 100876, China.

In this work, we only use data on the unstable manifold to locate the partition boundaries by checking folding points at different levels, which practically coincide with homoclinic tangencies. The method is then applied to the classic two-dimensional Hénon map and a well-known three-dimensional map. Comparison with previous results is made in the Hénon case, and Lyapunov exponents are computed through the metric entropy based on the partition to show the validity of the current scheme. Read More

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On the determination of the optimal parameters in the CAM model.

Chaos 2021 Mar;31(3):033113

Dipartimento di Fisica, Università di Pisa, 56126 Pisa (PI), Italy.

In the field of complex systems, it is often possible to arrive at some simple stochastic or chaotic Low Order Models (LOMs) exploiting the time scale separation between leading modes of interest and fast fluctuations. These LOMs, although approximate, might provide interesting qualitative insights regarding some important aspects like the average time between two extreme events. Recently, the simplest example of a LOM with multiplicative noise, namely, a linear system with a linearly state dependent noise [also called correlated additive and multiplicative (CAM) model], has been considered as archetypal for numerous phenomena that present markedly non-Gaussian statistics. Read More

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Parameter extraction with reservoir computing: Nonlinear time series analysis and application to industrial maintenance.

Chaos 2021 Mar;31(3):033122

ARC Centre for Transforming Maintenance Through Data Science, The University of Western Australia, Crawley, Western Australia 6009, Australia.

We study the task of determining parameters of dynamical systems from their time series using variations of reservoir computing. Averages of reservoir activations yield a static set of random features that allows us to separate different parameter values. We study such random feature models in the time and frequency domain. Read More

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