Aguilar-Canto, Fernando Javierde Leon, Ugo Avila-PonceAvila-Vales, Eric
18页
查看更多>>摘要：In response to the ongoing pandemic of COVID-19, several companies across the world have proposed a wide variety of vaccines of different mechanisms of action. As a consequence, a new scenario of multiple imperfect vaccines against the SARS-CoV-2 arose. Mathematical modeling needs to consider this complex situation with different vaccines, some of them with two required doses. Using compartmental models we can simplify, simulate and most importantly, answer questions related to the development of the outbreak and the vaccination campaign. We present a model that addresses the current situation of COVID19 and vaccination. Two important questions were considered in this paper: are more vaccines useful to reduce the spread of the coronavirus? How can we know if the vaccination campaign is sufficient? Two sensitivity criteria are helpful to answer these questions. The first criterion is the Multiple Vaccination Theorem, which indicates whether a vaccine is giving a positive or negative impact on the reproduction number. The second result (Insufficiency Theorem) provides a condition to answer the second question. Finally, we fitted the parameters with data and discussed the empirical results of six countries: Israel, Germany, the Czech Republic, Portugal, Italy, and Lithuania.(c) 2022 Elsevier Ltd. All rights reserved.
查看更多>>摘要：The evolutionary game of cyclic competition has been extensively studied to gain insight into one of the most fundamental phenomena in nature: biodiversity. The three-species Rock-Paper-Scissors (RPS) game and its extension Rock-Paper-Scissors-Lizard-Spock (RPSLS) game are typical models in this field. However, in real ecosystems, species richness can be easily influenced by the interaction structure among species. In this paper, we investigate species coexistence in modified RPSLS games by removing certain predator-prey interactions. We find that the interaction structure impacts the evolutionary dynamics and different interaction structures allow for different states of multi-species coexistence. We also find that the competition between different three-species-cyclic interactions is crucial for the realization of different asymptotic behaviors at low mobility. Our findings may be useful to understand the subtle effects of competitive structure on species coexistence and evolutionary game outcomes. (C) 2022 Elsevier Ltd. All rights reserved.
Romero-Bustamante, Jorge A. A.Velazquez-Camilo, OscarGarcia-Hernandez, AngelesRivera, Victor M. M....
10页
查看更多>>摘要：This work presents a proposal for the indirect monitoring of cane sugar crystallization using the multiscale analysis of temperature, pH, and torque time series. The time series were obtained at different crystallizer operating conditions; an experimental design considering four cooling profiles and three seed sizes was performed. Three multiscale methodologies (i.e., Detrended Fluctuation Analysis (DFA), R/S analysis, and Power Spectral Density (PSD)) were applied, identifying that the analyzed time series exhibit fractal behavior in three characteristic scale intervals, which suggests that the time series fluctuations may be a response to the interactions between transport phenomena inherent in the cane sugar crystallization process. By calculating the dynamic fractal dimension for the different characteristic scale intervals, correlations between the fractal dimension (FD) and the experimental measures of the key variables were identified, i.e., average crystal size,% volume, and formed mass crystal with FD calculated by temperature, pH, and torque time-series, respectively. Temperature, pH, and torque measurements are inexpensive, easy to implement, and can be obtained in real-time. The results suggest that multiscale time series analysis captured during the cane sugar crystallization has a high potential for indirect online monitoring with low economic and computational costs. (c) 2022 Elsevier Ltd. All rights reserved.
查看更多>>摘要：We investigate dynamical robustness in a network of oscillators having a simultaneous presence of attrac-tive coupling along with a repulsive coupling. Our study reveals that the interplay of attractive-repulsive interactions in oscillators gives rise to complex aging transition dynamics. In particular, we show that due to the counteracting effects of attractive-repulsive interactions, aging transition happens through both homogeneous as well as inhomogeneous steady state. Our result establishes that while attractive interac-tion decreases dynamical robustness, repulsive interaction might enhance it depending on the parameter space. Parameter values for which aging transition occurs through the homogeneous steady state, dynam-ical robustness improves with the increment of repulsive coupling strength. For aging transition through inhomogeneous steady state phase transition is quite dramatic. It follows a discontinuous jump in the order parameter mediated by the inhomogeneous steady state. We also show that depending upon dis-tinct coupling ranges, aging transition happens without a single inactive oscillator due to presence of inhomogneous steady state. We also study the bifurcations responsible for such complex aging transition phenomena.
Gorshkov, O. N.Agudov, N. V.Carollo, A.Valenti, D....
6页
查看更多>>摘要：The effects of temperature on the switching kinetics of an yttrium-stabilized zirconia-based memristor from a low-resistance state to a high-resistance state have been experimentally investigated. It was found that the memristor relaxation time depends on the temperature in a non-monotonous way, with a maximum observed at the temperature close to 55 degrees C. This nonmonotonic behavior is a signature of the noise-enhanced stability phenomenon observed in all physical and complex systems characterized by metastable states. (c) 2022 Elsevier Ltd. All rights reserved.
查看更多>>摘要：It is shown that the mathematical description of the ion transport across passive or active biological neuron membrane, voltage propagation along neuron axons and dendrites having passive or active membrane and ion transport in biological neuron networks, using general temporal Caputo or general temporal Riemann-Liouville fractional order derivatives, is objective. The basic idea is that different observers using this type of description obtain results which can be reconciled, i.e., transformed into each other using only formulas that link the coordinates of a point in two fixed orthogonal reference frames and the numbers representing a moment of time in two different choices of the origin of time measurement. This requirement was pointed out by Galileo Galilee (1564-1642), Isaac Newton (1643-1727), Albert Einstein (1879-1955) in the context of mathematical description of mechanical movement: "The mechanical event is independent on the observer ". (C) 2022 Published by Elsevier Ltd.
查看更多>>摘要：A stochastic cholera model with saturation recovery rate is discussed. Firstly, the existence and unique-ness of the global positive solution of the system are proved. Secondly, the asymptotic behavior of the solutions of the stochastic cholera model near the disease-free equilibrium and the corresponding de-terministic endemic equilibrium is discussed. Then, the phenomenon that the large noise can cause the extinction of cholera is obtained. Furthermore, on the basis of the stochastic model, the optimal control is added and studied to provide a theoretical basis for the prevention and control of cholera. Finally, the theoretical results are verified by numerical simulations and some suggestions on how to better control the disease are presented.(c) 2022 Elsevier Ltd. All rights reserved.
查看更多>>摘要：In this study, four specimens of pure tungsten, which have been irradiated with a high-temperature plasma with 20, 40, 60, and 80 pulses, respectively, are considered. Scanning electron microscopy (SEM) and optical microscope (OM) images of these specimens are used to search for more suitable degrees of darkness for binarizing the images for multifractal analysis. The multifractal characteristics obtained from SEM and OM images are then compared for the same specimens. The study shows the application of multifractal analysis to SEM images is robust enough as the change of binarization level in a range of 30-70% leads to a change of multifractal characteristics about 0.5%. It has been found that the optimal binarization level for OM images is about 10%.(c) 2022 Published by Elsevier Ltd.
查看更多>>摘要：The fractional Brownian motion (FBM) is a common model for long and short-range dependent phenomena that appears in different fields, including physics, biology, and finance. In the current work, a new spectral technique named the fractional Wiener Hermite Expansion (FWHE) is developed to analyze stochastic models with FBM. The technique has a theoretical background in the literature and proof of convergence. A new complete orthogonal Hermite basis set is developed. Calculus derivations and statistical analysis are performed to handle the mixed multi-dimensional fractional and/or integer-order integrals that appear in the analysis. Formulas for the mean and variance are deduced and are found to be based on fractional integrals. Using the developed expansion with the statistical properties of the basis functionals will help to reduce the stochastic model to equivalent deterministic fractional models that can be analyzed numerically or analytically with the well-known techniques. A numerical algorithm is developed to be used in case there is no available analytical solution. The numerical algorithm is compared with the fractional Euler-Maruyama (EM) technique to verify the results. In comparison to sampling based techniques, FWHE provides an efficient analytical or numerical alternative. The applicability of FWHE is demonstrated by solving different examples with additive and multiplicative FBM.
查看更多>>摘要：Phenomenological and deterministic models are often used for the estimation of transmission parameters in an epidemic and for the prediction of its growth trajectory. Such analyses are usually based on single peak outbreak dynamics. In light of the present COVID-19 pandemic, there is a pressing need to better understand observed epidemic growth with multiple peak structures, preferably using first-principles methods. Along the lines of our previous work [Physica A 574, 126014 (2021)], here we apply 2D random-walk Monte Carlo calculations to better understand COVID-19 spread through contact interactions. Lockdown scenarios and all other control interventions are imposed through mobility restrictions and a regulation of the infection rate within the stochastically interacting population. The susceptible, infected and recovered populations are tracked over time, with daily infection rates obtained without recourse to the solution of differential equations. The simulations were carried out for population densities corresponding to four countries, India, Serbia, South Africa and USA. In all cases our results capture the observed infection growth rates. More importantly, the simulation model is shown to predict secondary and tertiary waves of infections with reasonable accuracy. This predictive nature of multiple wave structures provides a simple and effective tool that may be useful in planning mitigation strategies during the present pandemic. (C) 2022 Elsevier Ltd. All rights reserved.
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