Article
Multidisciplinary Sciences
Clovis Ntahkie Takembo, Michael Ekonde Sone
Summary: This study investigates the effect of external electric fields on biological neurons, finding that such fields can induce cell polarization and charge fluctuations, thereby modulating the multiple firing modes of cell electrical activity. An improved neural network model explores wave propagation and mode transition of slightly perturbed plane waves, revealing wave patterns and mode transitions dependence on different parameters of external electric fields. The study shows that under certain conditions, external electric fields can lead to bursting synchronization in the neural network, potentially offering insights into the occurrence of epileptic seizures.
Article
Mechanics
Muhammad Ishaq, Zhi-Min Chen, Qingkai Zhao
Summary: In this study, the ideal fluid model of an inviscid fluid is considered, assuming adiabatic and incompressible flow that is irrotational. The derived system of equations describes motion in two dimensions using Laplace equation with appropriate boundary conditions. The nonlinear Korteweg-De Vries equation is derived to investigate the interaction of multiple periodic waves, revealing wave energy transfer and characteristics of solitons.
Article
Physics, Fluids & Plasmas
Fangping Wang, Juanfang Han, Wenshan Duan
Summary: In this study, analysis of the nonlinear coupled equations between a fast magnetosonic wave and a slow Alfven wave provided the dispersion relation and growth rate of the perturbation wave. It was observed that the growth rate increases with background magnetic field, and a critical perturbation wave number was identified.
PLASMA SCIENCE & TECHNOLOGY
(2021)
Article
Physics, Fluids & Plasmas
Jinbing Chen, Dmitry E. Pelinovsky
Summary: The DNLS equation is a model for studying nonlinear wave dynamics in plasma physics and optics. The study shows that rogue waves can only be localized in space-time if the periodic standing wave is modulationally unstable, otherwise they degenerate into algebraic solitons. The maximal amplitudes of rogue waves have been analytically derived and numerically confirmed.
Article
Optics
Stefano Negrini, Jean Baptiste Ceppe, Matteo Conforti, Auro M. Perego, Alexandre Kudlinski, Arnaud Mussot
Summary: In this study, we experimentally and numerically investigate the dynamics of a fiber ring cavity and demonstrate that two different instabilities can be excited individually or collectively depending on the control parameters of pump power and cavity detuning. The experimental observations are in good agreement with numerical simulations.
Article
Optics
Guillaume Vanderhaegen, Pascal Szriftgiser, Alexandre Kudlinski, Andrea Armaroli, Matteo Conforti, Stefano Trillo, Arnaud Mussot
Summary: We report the observation of parametric gain band distortion in the nonlinear regime of modulation instability in dispersion oscillating fibers. We show that the maximum gain is shifted beyond the boundaries of the linear parametric gain band. Experimental findings are validated using numerical simulations.
Article
Optics
Pan Wang, Jiangyong He, Xiaosheng Xiao, Zhi Wang, Yange Liu
Summary: This study presents theoretical investigations on the filter-induced instability mechanism in passive driven fiber resonators. Numerical simulations demonstrate coherent frequency combs with rates up to sub-terahertz level. The comparison with other types of instabilities reveals the intrinsic distinction in the family of modulation instabilities. These findings have significant implications for the development of ultrahigh-repetition-rate frequency comb generation.
PHOTONICS RESEARCH
(2022)
Article
Physics, Fluids & Plasmas
Y. He, A. Witt, S. Trillo, A. Chabchoub, N. Hoffmann
Summary: Modulation instability is a focusing mechanism that can generate strong wave localizations on water surfaces and in other nonlinear dispersive media. By studying the exact solutions of the nonlinear Schrodinger equation, it has been found that phase-shift localization applied to the background can trigger extreme events.
Article
Multidisciplinary Sciences
John Jumper, Richard Evans, Alexander Pritzel, Tim Green, Michael Figurnov, Olaf Ronneberger, Kathryn Tunyasuvunakool, Russ Bates, Augustin Zidek, Anna Potapenko, Alex Bridgland, Clemens Meyer, Simon A. A. Kohl, Andrew J. Ballard, Andrew Cowie, Bernardino Romera-Paredes, Stanislav Nikolov, Rishub Jain, Jonas Adler, Trevor Back, Stig Petersen, David Reiman, Ellen Clancy, Michal Zielinski, Martin Steinegger, Michalina Pacholska, Tamas Berghammer, Sebastian Bodenstein, David Silver, Oriol Vinyals, Andrew W. Senior, Koray Kavukcuoglu, Pushmeet Kohli, Demis Hassabis
Summary: Proteins are essential for life, and accurate prediction of their structures is a crucial research problem. Current experimental methods are time-consuming, highlighting the need for accurate computational approaches to address the gap in structural coverage. Despite recent progress, existing methods fall short of atomic accuracy in protein structure prediction.
Article
Physics, Multidisciplinary
Yiming Pan, Moshe-Ishay Cohen, Mordechai Segev
Summary: We propose superluminal solitons residing in the momentum gap (k gap) of nonlinear photonic time crystals. These solitons are structured as plane waves in space while periodically selfreconstructing wave packets in time. Compared to the stationary nature of Bragg gap solitons, the k-gap solitons emerge from modes with infinite group velocity, causing superluminal evolution.
PHYSICAL REVIEW LETTERS
(2023)
Article
Physics, Multidisciplinary
Yuchen He, Alexey Slunyaev, Nobuhito Mori, Amin Chabchoub
Summary: The study discusses the formation mechanism of nonlinear wave focusing and the role of modulation instability in this process. Experimental evidence is used to demonstrate that MI can still exist stably in the scenario of two counterpropagating wave trains, unaffected by the broadband or directional wave field.
PHYSICAL REVIEW LETTERS
(2022)
Article
Physics, Multidisciplinary
Daniel Leykam, Ekaterina Smolina, Aleksandra Maluckov, Sergej Flach, Daria A. Smirnova
Summary: The modulational instability of nonlinear Bloch waves in topological photonic lattices is influenced by topological band inversions, leading to the creation of topologically nontrivial wave fields. Nonlinear wave mixing plays a role in spreading energy through the entire band and creating wave polarization singularities.
PHYSICAL REVIEW LETTERS
(2021)
Article
Computer Science, Artificial Intelligence
Biao Sun, Chaoxu Mu, Zexu Wu, Xinshan Zhu
Summary: The article introduces a new CS framework called APGen for reconstructing action potentials without the need for training, providing higher accuracy, computational efficiency, and robustness. This method shows potential for long-term, resource-constrained, and large-scale wireless neural recording.
IEEE TRANSACTIONS ON NEURAL NETWORKS AND LEARNING SYSTEMS
(2022)
Article
Optics
A. Verbitskiy, A. Yulin, A. G. Balanov
Summary: We investigated the response of an optical system with Kerr nonlinearity to a periodic train of coherent pulses. The intensity of the excited field in the system was found to depend resonantly on the pulses' period. Numerical and analytical results demonstrated that the system's response is stronger when the pulse period is commensurate with the period of Bloch oscillations. Moreover, sufficiently large pulses can induce instabilities leading to chaotic Bloch oscillations of the wave-function envelope in both time and space. These instabilities are associated with period-doubling bifurcations, with a cascade of such bifurcations triggering the chaotic behavior.
Article
Biochemical Research Methods
Gang Xu, Qinghua Wang, Jianpeng Ma
Summary: The study developed an open-source toolkit named OPUS-X for predicting protein 3D structure, consisting of three modules: OPUS-TASS2, OPUS-Contact, and OPUS-Fold2. OPUS-TASS2 integrates global protein structure information, OPUS-Contact combines multiple raw features, and OPUS-Fold2 utilizes different protein folding methods.
Article
Computer Science, Hardware & Architecture
K. Zourmba, C. Fischer, J. Y. Effa, B. Gambo, A. Mohamadou
Summary: This study presents a simple and feasible third-order chaotic oscillator by bridging an inductor to implement a memristor bipole with an active Wien-bridge oscillator. The dynamical characteristics of the proposed circuit are investigated theoretically and numerically, revealing an unstable equilibrium point and various behaviors such as limit cycle orbit, quasi-periodic behavior, chaotic behavior, and bursting behavior. The feasibility of the theoretical model is confirmed through Pspice simulations and a physical realization based on an electronic analog implementation of the model.
JOURNAL OF CIRCUITS SYSTEMS AND COMPUTERS
(2023)
Article
Engineering, Mechanical
R. Mbakob Yonkeu, B. A. Guimfack, C. B. Tabi, A. Mohamadou, T. C. Kofane
Summary: This paper addresses the dynamics of a modified Van der Pol (VDP) oscillator driven by fractional time-delay feedback under correlated noise. It is found that the system exhibits tristability with the coexistence of three stable limit cycles in the deterministic case. The equivalent VDP equation is obtained using the generalized harmonic balance technique, and the stochastic averaging method provides analytical solutions for the equivalent stochastic equation. The critical parametric conditions for stochastic P-bifurcation are obtained, and the accuracy of the theoretical predictions is confirmed through comparison with direct numerical simulations.
NONLINEAR DYNAMICS
(2023)
Article
Engineering, Electrical & Electronic
P. H. Tatsing, A. C. Chamgoue, E. Kengne, A. Mohamadou, T. C. Kofane
Summary: We investigate the saturation effects on modulational instability (MI) in a model of three-core PIM-NIM-PIM coupler with Kerr-type saturable nonlinearity. The analytical results show significant changes in MI gain compared to previous studies without saturable parameter. Power and nonlinear parameters are found to be effective in controlling MI. Numerical simulation reveals the generation of periodic solitons in the presence of nonlinear saturation, while in the absence of saturable parameter, solitons transform into a turbulent state and MI occurs.
OPTICAL AND QUANTUM ELECTRONICS
(2023)
Article
Engineering, Mechanical
Thierry Kenne Tiayo, Armand Sylvin Eteme, Conrad Bertrand Tabi, Henri Paul Ekobena Fouda, Timoleon Crepin Kofane
Summary: This study investigates two-dimensional Ca2+ oscillations in a cell network with bidirectional paracrine signaling interactions. A proposed model based on Ca2+-induced Ca2+ release and the degradation of IP3 by a3-kinase shows the role of these factors in the propagation of intercellular Ca2+ wave. The strength of paracrine coupling and the leak rate of Ca2+ from the endoplasmic reticulum to the cytosol determine the synchronization and pattern formation of Ca2+ waves. Weak paracrine coupling leads to the appearance of spiral and target Ca2+ waves, while strong coupling results in disintegration into turbulent patterns.
NONLINEAR DYNAMICS
(2023)
Article
Optics
Martin Djoko, Alain Djazet, Conrad Bertrand Tabi, T. C. Kofane
Summary: We investigate the impact of higher-order correction terms of the nonlinear refractive index and nonlinear-gain absorption on soliton dynamics in a three-dimensional dissipative medium described by the (3+1)D CQS-CGL equation. Through direct numerical simulation, we find that these parameters significantly influence the formation of solitons. Different combinations of the parameters result in various soliton solutions, including bell-shaped, snail, and creeping dissipative solitons. The propagation distance is also an important parameter that affects soliton formation.
Article
Physics, Multidisciplinary
Camus Gaston Latchio Tiofack, Conrad Bertrand Tabi, Hippolyte Tagwo, Timoleon Crepin Kofane
Summary: This study addresses the modulational instability (MI) in an optical fiber under competing effects, including pure-quartic dispersion, self-steepening, and intrapulse Raman response. The self-steepening parameter reduces the maximum MI gain and frequency bandwidth. The combined effects of self-steepening and intrapulse Raman scattering result in more spectral windows in the gain spectrum due to increased Raman effect. Numerical results confirm the theoretical predictions, showing the emergence of ultrashort pulses trains and rogue wave breathing trains. Asymmetric sidebands appear in the spectral and temporal evolution of the pulse trains under increasing self-steepening effect, which can be reversed via the Raman scattering effect, demonstrating tunability of energy transfer between modes during signal propagation. This research provides further insights into mechanisms for generating ultrashort pulses in optical media under higher-order nonlinearities, with potential applications in silicon photonic crystal waveguides and silica photonic crystal fibers.
Article
Engineering, Mechanical
L. Tiam Megne, C. B. Tabi, J. A. Ambassa Otsobo, C. M. Muiva, T. C. Kofane
Summary: This paper presents an explicit derivation of a (3+1)-dimensional cubic-quintic-septic complex Ginzburg-Landau equation, which describes the dynamics of dissipative light bullets in nonlinear metamaterials. Numerical simulations show the evolution of various dissipative optical bullets in metamaterials with different topological charges. It is found that with the right choice of higher-order parameters, the stability of the system can be achieved.
NONLINEAR DYNAMICS
(2023)
Article
Physics, Multidisciplinary
Blaise P. Edouma Biloa, Conrad B. Tabi, Henri P. Ekobena Fouda, Timoleon Kofane
Summary: This paper addresses the existence of modulated nonlinear periodic wave trains in a system of self-propelled particles. The mathematical model used in the study is reduced to a one-dimensional complex Ginzburg-Landau equation. The modulational instability phenomenon and solutions for the model equations are analyzed and discussed.
Article
Materials Science, Multidisciplinary
Edmond B. Madimabe, Conrad B. Tabi, Camus G. Latchio Tiofack, Timoleon C. Kofane
Summary: This paper demonstrates the existence of modulational instability in nonlinear exciton-polariton condensates. The growth rate expression is derived through linear stability analysis of continuous waves, and a parametric study of modulational instability is conducted. The results show that the photonic spin-orbit coupling and the pumping power have an impact on the growth rate spectrum.
Article
Physics, Fluids & Plasmas
Conrad Bertrand Tabi, Etienne Wamba, Emmanual Nare, Timoleon Crepin Kofane
Summary: This study investigates the nonlinear dynamics induced by the modulation instability of a binary mixture in an atomic Bose-Einstein condensate, considering the effects of higher-order residual nonlinearities and helicoidal spin-orbit coupling. The analysis is based on modified coupled Gross-Pitaevskii equations, and the stability of plane-wave solutions is studied to obtain the modulation instability gain. Parametric analysis reveals regions of instability and the effects of higher-order interactions and spin-orbit coupling under different combinations of interaction strengths. Numerical calculations support the analytical predictions, showing that the residual nonlinearity can preserve and reinforce the stability of miscible pairs of condensates with spin-orbit coupling.
Article
Physics, Multidisciplinary
C. N. Takembo, H. P. E. Fouda, T. C. Kofane
Summary: This paper investigates the impact of electric field on the emergence and propagation of a nonlinear wave impulse in an improved neuronal network. The angular frequency of the modulated impulse wave along the network is obtained through the application of the multiple scale expansion method. The frequency is found to be dependent on the electric field feedback gain and the coupling strength of the network. The results confirm the formation of localized nonlinear wave patterns and show that electric feedback gain and high-frequency field promote the emergence of chaotic-like wave patterns, while high-intensity external electric field suppresses wave patterns completely. The sampled time series analysis reveals that high-intensity external field suppresses electrical activities by reducing the output to a quiescent state. Extensive numerical simulations also demonstrate burst synchronization in the network, recurrently manifesting as paroxysmal epilepsy.
INDIAN JOURNAL OF PHYSICS
(2023)
Article
Physics, Multidisciplinary
R. Kengne, M. Motchongom Tingue, A. Kammogne Souop Tewa, G. Djuidje Kenmoe, T. C. Kofane
Summary: This paper addresses the optimal phase control in a system with Remoissenet-Peyrard substrate potential through numerical and analogical investigations. The numerical results show that the behavior of the system can be controlled from chaotic dynamics to periodic dynamics by applying a weak perturbation parameter to the elastic and friction terms of the equation describing the motion of the system. The analogical results confirm the stick-slip phenomenon in the system and demonstrate the effectiveness of the control strategy.
INDIAN JOURNAL OF PHYSICS
(2023)
Article
Mathematics, Interdisciplinary Applications
Bo Li, Tian Huang
Summary: This paper proposes an approximate optimal strategy based on a piecewise parameterization and optimization (PPAO) method for solving optimization problems in stochastic control systems. The method obtains a piecewise parameter control by solving first-order differential equations, which simplifies the control form and ensures a small model error.
CHAOS SOLITONS & FRACTALS
(2024)
Article
Mathematics, Interdisciplinary Applications
Guram Mikaberidze, Sayantan Nag Chowdhury, Alan Hastings, Raissa M. D'Souza
Summary: This study explores the collective behavior of interacting entities, focusing on the co-evolution of diverse mobile agents in a heterogeneous environment network. Increasing agent density, introducing heterogeneity, and designing the network structure intelligently can promote agent cohesion.
CHAOS SOLITONS & FRACTALS
(2024)
Article
Mathematics, Interdisciplinary Applications
Gengxiang Wang, Yang Liu, Caishan Liu
Summary: This investigation studies the impact behavior of a contact body in a fluidic environment. A dissipated coefficient is introduced to describe the energy dissipation caused by hydrodynamic forces. A new fluid damping factor is derived to depict the coupling between liquid and solid, as well as the coupling between solid and solid. A new coefficient of restitution (CoR) is proposed to determine the actual physical impact. A new contact force model with a fluid damping factor tailored for immersed collision events is proposed.
CHAOS SOLITONS & FRACTALS
(2024)
