2,960 results match your criteria equilibrium points

Discrete dynamical models on infection frequency in mosquito populations with biased release ratios.

Yantao Shi Bo Zheng

J Biol Dyn 2021 Sep 17:1-20. Epub 2021 Sep 17.

College of Mathematics and Information Sciences, Guangzhou University, Guangzhou, People's Republic of China.

We develop two discrete models to study how supplemental releases affect the spreading dynamics in cage mosquito populations. The first model focuses on the case when only infected males are released at each generation. This release strategy has been proved to be capable of speeding up the persistence by suppressing the compatible matings between uninfected individuals. Read More

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September 2021

Modeling the impact of early interventions on the transmission dynamics of coronavirus infection.

F1000Res 2021 30;10:518. Epub 2021 Jun 30.

Department of Engineering, School of Engineering, University for Development Studies,, Tamale,, UER, +233, Ghana.

A deterministic model is proposed to describe the transmission dynamics of coronavirus infection with early interventions. Epidemiological studies have employed modeling to unravel knowledge that transformed the lives of families, communities, nations and the entire globe. The study established the stability of both disease free and endemic equilibria. Read More

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Farming awareness based optimum interventions for crop pest control.

Math Biosci Eng 2021 Jun;18(5):5364-5391

Center for Research and Development in Mathematics and Applications (CIDMA), Department of Mathematics, University of Aveiro, 3810-193 Aveiro, Portugal.

We develop a mathematical model, based on a system of ordinary differential equations, to the upshot of farming alertness in crop pest administration, bearing in mind plant biomass, pest, and level of control. Main qualitative analysis of the proposed mathematical model, akin to both pest-free and coexistence equilibrium points and stability analysis, is investigated. We show that all solutions of the model are positive and bounded with initial conditions in a certain significant set. Read More

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Reproduction number and sensitivity analysis of cassava mosaic disease spread for policy design.

Math Biosci Eng 2021 Jun;18(5):5069-5093

School of Crop Production Technology, Suranaree University of Technology, Nakhon Ratchasima 30000, Thailand.

We develop a mathematical model for the dynamics of Cassava Mosaic Disease (CMD), which is driven by both planting of infected cuttings and whitefly transmission. We use the model to analyze the dynamics of a CMD outbreak and to identify the most cost-effective policy for controlling it. The model uses the reproduction number $ \mathscr{R}_0 $ as a threshold, calculated using the Next-Generation Method. Read More

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Chaotic dynamics in a novel COVID-19 pandemic model described by commensurate and incommensurate fractional-order derivatives.

Nonlinear Dyn 2021 Sep 3:1-13. Epub 2021 Sep 3.

Dipartimento Ingegneria Innovazione, Universita del Salento, 73100 Lecce, Italy.

Mathematical models based on fractional-order differential equations have recently gained interesting insights into epidemiological phenomena, by virtue of their memory effect and nonlocal nature. This paper investigates the nonlinear dynamic behavior of a novel COVID-19 pandemic model described by commensurate and incommensurate fractional-order derivatives. The model is based on the Caputo operator and takes into account the daily new cases, the daily additional severe cases, and the daily deaths. Read More

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September 2021

Optimal ligand discrimination by asymmetric dimerization and turnover of interferon receptors.

Proc Natl Acad Sci U S A 2021 Sep;118(37)

Institute for Theoretical Physics, Heidelberg University, 69120 Heidelberg, Germany;

In multicellular organisms, antiviral defense mechanisms evoke a reliable collective immune response despite the noisy nature of biochemical communication between tissue cells. A molecular hub of this response, the interferon I receptor (IFNAR), discriminates between ligand types by their affinity regardless of concentration. To understand how ligand type can be decoded robustly by a single receptor, we frame ligand discrimination as an information-theoretic problem and systematically compare the major classes of receptor architectures: allosteric, homodimerizing, and heterodimerizing. Read More

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September 2021

Analysis of fractional model of guava for biological pest control with memory effect.

J Adv Res 2021 09 10;32:99-108. Epub 2020 Dec 10.

Department of Mathematics, Faculty of Arts and Sciences, Cankaya University, Eskisehir Yolu 29. Km, Yukarıyurtcu Mahallesi Mimar Sinan Caddesi No: 4 06790, Etimesgut, Turkey.

Introduction: Fractional operators find their applications in several scientific and engineering processes. We consider a fractional guava fruit model involving a non-local additionally non-singular fractional derivative for the interaction into guava pests and natural enemies. The fractional guava fruit model is considered as a Lotka-Volterra nature. Read More

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September 2021

Stability behavior of a two-susceptibility SHIR epidemic model with time delay in complex networks.

Nonlinear Dyn 2021 Aug 30:1-28. Epub 2021 Aug 30.

School of Mathematics, Hunan University, Changsha, 410082 People's Republic of China.

Taking two susceptible groups into account, we formulate a modified subhealthy-healthy-infected-recovered (SHIR) model with time delay and nonlinear incidence rate in networks with different topologies. Concretely, two dynamical systems are designed in homogeneous and heterogeneous networks by utilizing mean field equations. Based on the next-generation matrix and the existence of a positive equilibrium point, we derive the basic reproduction numbers and which depend on the model parameters and network structure. Read More

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Chaos control in a multiple delayed phytoplankton-zooplankton model with group defense and predator's interference.

Chaos 2021 Aug;31(8):083101

Department of Mathematics, BITS Pilani, Pilani Campus, Pilani 333031, Rajasthan, India.

Phytoplankton-zooplankton interaction is a topic of high interest among the interrelationships related to marine habitats. In the present manuscript, we attempt to study the dynamics of a three-dimensional system with three types of plankton: non-toxic phytoplankton, toxic producing phytoplankton, and zooplankton. We assume that both non-toxic and toxic phytoplankton are consumed by zooplankton via Beddington-DeAngelis and general Holling type-IV responses, respectively. Read More

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A hyperchaotic cycloid map with attractor topology sensitive to system parameters.

Chaos 2021 Aug;31(8):083132

School of Physics and Electronics, Central South University, Changsha 410083, China.

We propose herein a novel discrete hyperchaotic map based on the mathematical model of a cycloid, which produces multistability and infinite equilibrium points. Numerical analysis is carried out by means of attractors, bifurcation diagrams, Lyapunov exponents, and spectral entropy complexity. Experimental results show that this cycloid map has rich dynamical characteristics including hyperchaos, various bifurcation types, and high complexity. Read More

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Handling of beam spectra in training and application of proton RBE models.

Phys Med Biol 2021 Sep 16;66(18). Epub 2021 Sep 16.

Medical Radiation Sciences, Department of Immunology, Genetics and Pathology, Uppsala University, Akademiska Sjukhuset, Uppsala, Sweden.

Published data from cell survival experiments are frequently used as training data for models of proton relative biological effectiveness (RBE). The publications rarely provide full information about the primary particle spectrum of the used beam, or its content of heavy secondary particles. The purpose of this paper is to assess to what extent heavy secondary particles may have been present in published cell survival experiments, and to investigate the impact of non-primary protons for RBE calculations in treatment planning. Read More

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September 2021

Transmission dynamic of stochastic hepatitis C model by spectral collocation method.

Comput Methods Biomech Biomed Engin 2021 Aug 30:1-15. Epub 2021 Aug 30.

Department of Mathematics, HITEC University, Pakistan.

In this research work, we present an exciting mathematical analysis of a stochastic model, using a standard incidence function, for infectious disease hepatitis C transmission dynamics. In this model, we divided the infected population into three different classes with two different infection stages known as chronic class and acute class while the third is an isolation class. We also presents briefly the Legendre spectral method for the numerical solution to the proposed model. Read More

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Smart Hydrogels: Preparation, Characterization, and Determination of Transition Points of Crosslinked -Isopropyl Acrylamide/Acrylamide/Carboxylic Acids Polymers.

Gels 2021 Aug 8;7(3). Epub 2021 Aug 8.

Chemistry Department, Science Faculty, Sivas Cumhuriyet University, Sivas 58140, Turkey.

Smart hydrogels (SH) were prepared by thermal free radical polymerization of -isopropyl acrylamide (NIPAAm), acrylamide (AAm) with acrylic acid (A) or maleic acid (M), and ,'-methylene bisacrylamide. Spectroscopic and thermal characterizations of SHs were performed using FTIR, TGA, and DSC. To determine the effects of SHs on swelling characteristics, swelling studies were performed in different solvents, solutions, temperatures, pHs, and ionic strengths. Read More

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Electrochemical properties of the non-excitable tissue stria vascularis of the mammalian cochlea are sensitive to sounds.

J Physiol 2021 Aug 23. Epub 2021 Aug 23.

Division of Glocal Pharmacology, Department of Pharmacology, Graduate School of Medicine, Osaka University, Suita, Osaka, Japan.

Excitable cochlear hair cells convert the mechanical energy of sounds into the electrical signals necessary for neurotransmission. The key process is cellular depolarization via K entry from K -enriched endolymph through hair cells' mechanosensitive channels. Positive 80 mV potential in endolymph accelerates the K entry, thereby sensitizing hearing. Read More

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Fractional optimal control of COVID-19 pandemic model with generalized Mittag-Leffler function.

Adv Differ Equ 2021 19;2021(1):387. Epub 2021 Aug 19.

Mathematics Department, City University of Science and Information Technology, Peshawar, Pakistan.

In this paper, we consider a fractional COVID-19 epidemic model with a convex incidence rate. The Atangana-Baleanu fractional operator in the Caputo sense is taken into account. We establish the equilibrium points, basic reproduction number, and local stability at both the equilibrium points. Read More

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Exponentially Accelerated Approach to Stationarity in Markovian Open Quantum Systems through the Mpemba Effect.

Phys Rev Lett 2021 Aug;127(6):060401

Institut für Theoretische Physik, Universität Tübingen, Auf der Morgenstelle 14, 72076 Tübingen, Germany.

Ergodicity breaking and slow relaxation are intriguing aspects of nonequilibrium dynamics both in classical and quantum settings. These phenomena are typically associated with phase transitions, e.g. Read More

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Protection against allergies: Microbes, immunity, and the farming effect.

Eur J Immunol 2021 Aug 20. Epub 2021 Aug 20.

Institute for Asthma and Allergy Prevention, Helmholtz Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany.

The prevalence of asthma and other allergic diseases has rapidly increased in "Westernized" countries over recent decades. This rapid increase suggests the involvement of environmental factors, behavioral changes or lifestyle, rather than genetic drift. It has become increasingly clear that the microbiome plays a key role in educating the host immune system and, thus, regulation of disease susceptibility. Read More

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Breaking of time-reversal symmetry for a particle in a parabolic potential that is subjected to Lévy noise: Theory and an application to solar flare data.

Phys Rev E 2021 Jul;104(1-1):014119

Department of Physics, East Carolina University, Greenville, North Carolina 27858, USA.

The noise in nonequilibrium systems commonly contains more outliers as compared to equilibrium systems and is often best described with a Lévy distribution. Many systems in which there are fluctuations around a steady-state throughput can be modeled as a Lévy-noise-subjected particle in a parabolic potential. We consider an overdamped particle in a parabolic potential that is subjected to noise. Read More

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Mathematical analysis of a measles transmission dynamics model in Bangladesh with double dose vaccination.

Sci Rep 2021 Aug 16;11(1):16571. Epub 2021 Aug 16.

School of Computing and Mathematics, Charles Sturt University, Wagga Wagga, NSW, 2678, Australia.

Although the availability of the measles vaccine, it is still epidemic in many countries globally, including Bangladesh. Eradication of measles needs to keep the basic reproduction number less than one [Formula: see text]. This paper investigates a modified (SVEIR) measles compartmental model with double dose vaccination in Bangladesh to simulate the measles prevalence. Read More

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A SEIR model with memory effects for the propagation of Ebola-like infections and its dynamically consistent approximation.

Comput Methods Programs Biomed 2021 Sep 29;209:106322. Epub 2021 Jul 29.

Department of Mathematics, Faculty of Sciences, University of Central Punjab, Lahore, Pakistan. Electronic address:

Background And Objective: We present and analyze a nonstandard numerical method to solve an epidemic model with memory that describes the propagation of Ebola-type diseases. The epidemiological system contemplates the presence of sub-populations of susceptible, exposed, infected and recovered individuals, along with nonlinear interactions between the members of those sub-populations. The system possesses disease-free and endemic equilibrium points, whose stability is studied rigorously. Read More

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September 2021

A computational theory for the production of limb movements.

Emmanuel Guigon

Psychol Rev 2021 Aug 12. Epub 2021 Aug 12.


Motor control is a fundamental process that underlies all voluntary behavioral responses. Several different theories based on different principles (task dynamics, equilibrium-point theory, passive-motion paradigm, active inference, optimal control) account for specific aspects of how actions are produced, but fail to provide a unified view on this problem. Here, we propose a concise theory of motor control based on three principles: optimal feedback control, control with a receding time horizon, and task representation by a series of via-points updated at fixed frequency. Read More

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Gas-cycle-assisted headspace solid-phase microextraction coupled with gas chromatography for rapid analysis of organic pollutants.

Chem Commun (Camb) 2021 Sep 12;57(70):8810-8813. Epub 2021 Aug 12.

Henan International Joint Laboratory of Medicinal Plants Utilization, College of Chemistry and Chemical Engineering, Henan University, Kaifeng 475004, Henan, China.

Herein, a new gas-cycle-assisted (GCA) headspace solid-phase microextraction (HS-SPME) device was designed to rapidly extract organic pollutants with high K and boiling points, which have difficulty in volatilization from matrix to headspace. Organic pollutants, including three polycyclic aromatic hydrocarbons (PAHs), four polychlorinated biphenyls (PCBs), and five phthalate esters (PAEs), were selected to evaluate the performance of GCA HS-SPME. Compared with conventional HS-SPME, the equilibrium times of GCA HS-SPME for extraction of PAHs, PCBs, and PAEs were greatly shortened from 70-90 to 5-11 min. Read More

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September 2021

Dynamics of Tuberculosis (TB) with Drug Resistance to First-Line Treatment and Leaky Vaccination: A Deterministic Modelling Perspective.

Comput Math Methods Med 2021 27;2021:5593864. Epub 2021 Jul 27.

Department of Mathematics and Statistics, University of Energy and Natural Resources, Sunyani, Ghana.

A deterministic model was formulated and employed in the analysis of the dynamics of tuberculosis with a keen emphasis on vaccination and drug resistance as the first line of treatment. It was assumed that some of the susceptible population were vaccinated but with temporal immunity. This is due to the fact that vaccines do not confer permanent immunity. Read More

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Analytic approaches to periodically driven closed quantum systems: methods and applications.

J Phys Condens Matter 2021 Aug 24;33(44). Epub 2021 Aug 24.

School of Physical Sciences, Indian Association for the Cultivation of Science, 2A and 2B Raja S C Mullick Road, Jadavpur 700032, India.

We present a brief overview of some of the analytic perturbative techniques for the computation of the Floquet Hamiltonian for a periodically driven, or Floquet, quantum many-body system. The key technical points about each of the methods discussed are presented in a pedagogical manner. They are followed by a brief account of some chosen phenomena where these methods have provided useful insights. Read More

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Computational Analysis of Oscillatory Bio-Signals: Two-Parameter Bifurcation Diagrams.

Entropy (Basel) 2021 Jul 8;23(7). Epub 2021 Jul 8.

Department of Computer Science, Opole University of Technology, 45-758 Opole, Poland.

Two types of bifurcation diagrams of cytosolic calcium nonlinear oscillatory systems are presented in rectangular areas determined by two slowly varying parameters. Verification of the periodic dynamics in the two-parameter areas requires solving the underlying model a few hundred thousand or a few million times, depending on the assumed resolution of the desired diagrams (color bifurcation figures). One type of diagram shows oscillations, that is, periodic oscillations having maximum values in one period. Read More

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Analysis and Design of Multivalued High-Capacity Associative Memories Based on Delayed Recurrent Neural Networks.

IEEE Trans Cybern 2021 Aug 4;PP. Epub 2021 Aug 4.

This article aims at analyzing and designing the multivalued high-capacity-associative memories based on recurrent neural networks with both asynchronous and distributed delays. In order to increase storage capacities, multivalued activation functions are introduced into associative memories. The stored patterns are retrieved by external input vectors instead of initial conditions, which can guarantee accurate associative memories by avoiding spurious equilibrium points. Read More

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Multistability of Dynamic Memristor Delayed Cellular Neural Networks With Application to Associative Memories.

IEEE Trans Neural Netw Learn Syst 2021 Aug 4;PP. Epub 2021 Aug 4.

Recently, dynamic memristor (DM)-cellular neural networks (CNNs) have received widespread attention due to their advantage of low power consumption. The previous works showed that DM-CNNs have at most 318 equilibrium points (EPs) with n=16 cells. Since time delay is unavoidable during the process of information transmission, the goal of this article is to research the multistability of DM-CNNs with time delay, and, meanwhile, to increase the storage capacity of DM-delay (D)CNNs. Read More

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Subcritical Andronov-Hopf scenario for systems with a line of equilibria.

Chaos 2021 Jul;31(7):073102

FEMTO-ST Institute/Optics Department, CNRS and University Bourgogne Franche-Comté, 15B avenue des Montboucons, Besançon Cedex 25030, France.

Using numerical simulation methods and analytical approaches, we demonstrate hard self-oscillation excitation in systems with infinitely many equilibrium points forming a line of equilibria in the phase space. The studied bifurcation phenomena are equivalent to the excitation scenario via the subcritical Andronov-Hopf bifurcation observed in classical self-oscillators with isolated equilibrium points. The hysteresis and bistability accompanying the discussed processes are shown and explained. Read More

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The Impact of Functional and Structural Maturation of the Kidney on Susceptibility to Drug and Chemical Toxicity in Neonatal Rodents.

Toxicol Pathol 2021 Aug 2:1926233211035683. Epub 2021 Aug 2.

Private Consultant, Alligator Point, FL, USA.

Drug responses are often unpredictable in juvenile animal toxicity studies; hence, optimizing dosages is challenging. Renal functional differences based on age of development will often result in vastly different toxicologic responses. Developmental changes in renal function can alter plasma clearance of compounds with extensive renal elimination. Read More

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Analytic and Integrative Framework for Understanding Human Sympathetic Arterial Baroreflex Function: Equilibrium Diagram of Arterial Pressure and Plasma Norepinephrine Level.

Front Neurosci 2021 16;15:707345. Epub 2021 Jul 16.

Department of Biomedical Engineering, Autonomic Dysfunction Center, Vanderbilt University Medical Center, Vanderbilt University, Nashville, TN, United States.

Background: The sympathetic arterial baroreflex is a closed-loop feedback system for stabilizing arterial pressure (AP). Identification of unique functions of the closed system in humans is a challenge. Here we propose an analytic and integrative framework for identifying a static operating point and open-loop gain to characterize sympathetic arterial baroreflex in humans. Read More

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