The pandemic COVID-19 has caused severe losses in public health and economy. One of the most difficult problems in prevention of the disease spread is the emergence of new variants. In this paper, a ...mathematical model is formulated, which captures the main feature of COVID-19 spread with two viral strains. It is shown by analytical method that the model exhibits the competitive exclusion principle, where one viral strain with the larger basic reproduction number is dominant and the viral strain with the smaller reproduction number is excluded. The results are important for the deployment of prevention policy of COVID-19.
The theory of the principal eigenvalue is developed for an elliptic eigenvalue problem associated with a linear parabolic cooperative system with some zero diffusion coefficients. Then the basic ...reproduction number and its computation formulae are established for reaction-diffusion epidemic models with compartmental structure. These theoretical results are applied to a spatial model of rabies to study the influence of spatial heterogeneity and population mobility on disease transmission. PUBLICATION ABSTRACT
In this paper, we consider a class of non-cooperative diffusion–reaction systems, which include prey–predator models and disease-transmission models. The concept of weak traveling wave solutions is ...proposed. The necessary and sufficient conditions for the existence of such solutions are obtained by the Schauder's fixed-point theorem and persistence theory. The introduction of persistence theory is very technical and crucial. The LaSalle's invariance principle is applied to show that traveling wave solutions connect two equilibria. The nonexistence of traveling wave solutions is proved by introducing a negative one-sided Laplace transform. The results are applied to a prey–predator model and a disease-transmission model with specific interaction functions. We find that the profile of traveling wave solutions may depend on different eigenvalues according to the corresponding condition, which is a new phenomenon.
Steep-slope vineyards are widely distributed in the Mediterranean region and have a pivotal role in wine production, economic development, and cultural heritage. Nevertheless, they are threatened by ...climate change in terms of opposite weather extremes, such as heavy rainfalls and long-lasting droughts. In response, rainwater harvesting systems have emerged as valuable solutions for managing water resources and controlling related problems. Of primary importance is the identification of suitable sites for installation. However, a systematic selection procedure still needs to be explored; it is necessary for morphologically complex vineyards that include historical features of significant cultural value (such as terraced systems). To fill this gap, this study employed a high-resolution overflow simulation model that combines a set of criteria to identify the optimal network of water harvesting structures (also drawing on traditional knowledge) and quantify the potential for water storage during rainfall of varying intensities. The study area considered is located within the “Soave Traditional Vineyards” (north of Italy) site, a Globally Important Agricultural Heritage System (GIAHS) recognized by FAO. The surface overflow was simulated considering two key rainstorms that occurred in the last few years at different time intervals. 53 potential sites for water harvesting were selected according to field survey, runoff simulation, and topographic analysis. The results indicate that the water potentially collected from designed sites could have a double function: (1) mitigate the surface overflow that can potentially cause downslope terrace collapse or even flooding villages; (2) provide irrigation water for vineyards during water scarcity scenarios. The spatial distribution of the water collected could undoubtedly guide sustainable decisions in steep-slope viticultural systems under climate change forcing.
•Steep-slope vineyards are a cultural heritage threatened by increasing weather extremes: intense rainfall and drought.•A prototype of low-impact micro storages is tested to improve resilience to climate change of steep-slope viticulture.•High-resolution topography is necessary to optimally identify rainwater harvesting facilities.•Micro-water storage can significantly reduce runoff and harvest water for emergency irrigation.
A mathematical model is proposed that incorporates the key routes of COVID-19 resurgence: human-to-human transmission and indirect transmission by inhaling infectious aerosols or contacting public ...facilities with the virus. The threshold condition for the disease invasion is established, and the relationships among the basic reproduction number, peak value and final size are formulated. The model is validated by matching the model with the data on cases of COVID-19 resurgence in April of 2020 from Heilongjiang province in China, which indicates that the predictive values from the mathematical model fit the real data very well. Based upon the computations from the model and analytical formulae, we reveal how the indirect transmission from environmental pathogens contribute to the disease outbreak and how the input of asymptomatic individuals affect the disease spread. These findings highlight the importance of mass detection and environmental disinfection in the control of COVID resurgence.
While long-term dynamic breath-holding training has been extensively studied to enhance cardiopulmonary function in athletes, limited research has explored the impact of a single breath-holding ...session on subsequent athletic capacity. In addition, Dry Dynamic Apnea (DA) has a more immediate physiological response than wet and static breath-holding. This study aims to assess the immediate effects of a single session of DA on the aerobic power and hematological parameters of elite athletes.
Seventeen elite male rugby athletes (average age 23.5 ± 1.8) participated in this study. Two warm-up protocols were employed prior to incremental exercise: a standard warm-up (10 min of no-load pedaling) and a DA warm-up (10 min of no-load pedaling accompanied by six maximum capacity breath holds, with 30 s between each breath hold). Fingertip blood indicators were measured before and after warm-up. The incremental exercise test assessed aerobic parameters with self-regulation applied throughout the study.
Compared to the baseline warm-up, the DA warm-up resulted in a significant increase in VO2peak from 3.14 to 3.38 L/min (7.64% change,
< 0.05). HRmax increased from 170 to 183 bpm (7.34% change,
< 0.05), and HRpeak increased from 169 to 182 bpm (7.52% change,
< 0.05). Hematocrit and hemoglobin showed differential changes between the two warm-up methods (P
= 0.674; P
= 0.707).
This study investigates how DA influences physiological factors such as spleen contraction, oxygen uptake, and sympathetic nerve activation compared to traditional warm-up methods. Immediate improvements in aerobic power suggest reduced vagus nerve stimulation, heightened sympathetic activity, and alterations in respiratory metabolism induced by the voluntarily hypoxia-triggered warm-up. Further research is warranted to comprehensively understand these physiological responses and optimize warm-up strategies for elite athletic performance.
The basic reproduction ratio and its computation formulae are established for a large class of compartmental epidemic models in periodic environments. It is proved that a disease cannot invade the ...disease-free state if the ratio is less than unity and can invade if it is greater than unity. It is also shown that the basic reproduction number of the time-averaged autonomous system is applicable in the case where both the matrix of new infection rate and the matrix of transition and dissipation within infectious compartments are diagonal, but it may underestimate and overestimate infection risks in other cases. The global dynamics of a periodic epidemic model with patch structure is analyzed in order to study the impact of periodic contacts or periodic migrations on the disease transmission.
A nonlocal and time-delayed reaction-diffusion model of dengue fever is first proposed that incorporates the aquatic stage, the winged stage, and the incubation periods of the dengue virus within ...mosquitos and hosts. Then the basic reproduction number R₀ is established for the model system, and an explicit formula of R₀ is obtained in the case of spatially homogeneous infections. It is shown that this R₀ gives the threshold dynamics in the sense that the disease-free equilibrium is asymptotically stable if R₀ < 1 and the disease is uniformly persistent if R₀ > 1. The influences of diffusion coefficients, time delays, and infection heterogeneity on the spread of the disease are also studied via numerical simulations. It turns out that the infection risk may be underestimated if the spatially averaged parameters are used to compute the basic reproduction number for spatially heterogeneous infections.
New services, such as distributed photovoltaic regulation and control, pose new service requirements for communication networks in the new power system. These requirements include low latency, high ...reliability, and large bandwidth. Consequently, power heterogeneous communication networks face the challenge of maintaining quality of service (QoS) while enhancing network resource utilization. Therefore, this paper puts forward a highly efficient optimization algorithm for resource slicing and scheduling in power heterogeneous communication networks. Our first step involves establishing an architectural description model of heterogeneous wireless networks for electric power based on hypergraph. This model characterizes complex dynamic relationships among service requirements, virtual networks, and physical networks. The system congruence entropy characterizes the degree of matching between the service demand and resource supply. Then an optimization problem is formed to maximize the system congruence entropy through dynamic resource allocation. To solve this problem, a joint resource allocation and routing method based on Lagrangian dual decomposition is proposed. These methods provide the optimal solutions of the nodes and link mappings of service function chains. The simulation results demonstrate that the proposed algorithm in this paper can greatly enhance resource utilization and also meet the QoS requirements of various services.
In response to the escalating demand for real-time and accurate fault detection in power transmission lines, this paper undertook an optimization of the existing YOLOv4 network. This involved the ...substitution of the main feature extraction network within the original YOLOv4 model with a lighter EfficientNet network. Additionally, the inclusion of Grouped Convolution modules in the feature pyramid structure replaced conventional convolution operations. The resulting model not only reduced model parameters but also effectively ensured detection accuracy. Moreover, in enhancing the model's reliability, data augmentation techniques were employed to bolster the robustness of the power transmission line fault detection algorithm. This optimization further utilized the DIoU loss function to stabilize target box regression. Comparative experiments demonstrated the improved YOLOv4 model's superior performance in terms of loss function optimization while significantly enhancing detection speed under equivalent configurations. The parameter capacity was reduced by 81%, totaling merely 43.65 million, while the frame rate surged by 85% to achieve 24 frames per second. These experimental findings validate the effectiveness of the algorithm.
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