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Feedback loops between strategies and the environment are commonly observed in socio-ecological, evolution-ecological, and psychology-economic systems. However, the impact of mutations in these feedback processes is often overlooked. This study proposes a novel model that integrates the public goods game with environmental feedback, considering the presence of mutations. In our model, the enhancement factor of the public goods game combines positive and negative incentives from the environment. By employing replicator–mutator (RM) equations, we provide an objective understanding of the system's evolutionary state, focusing on identifying conditions that foster cooperation and prevent the tragedy of the commons. Specifically, mutations play a crucial role in the RM dynamics, leading to the emergence of an oscillatory tragedy of the commons. By verifying the Hopf bifurcation condition, we establish the existence of a stable limit cycle, providing valuable insights into sustained oscillation strategies. Moreover, the feedback mechanism inherent in the public goods game model offers a fresh perspective on effectively addressing the classic dilemma of the tragedy of the commons. [ABSTRACT FROM AUTHOR]

Complex networks are widespread in real-world environments across diverse domains. Real-world networks tend to form spontaneously through interactions between individual agents. Inspired by this, we design an evolutionary game model in which agents participate in a prisoner's dilemma game (PDG) with their neighboring agents. Agents can autonomously modify their connections with neighbors using reinforcement learning to avoid unfavorable environments. Interestingly, our findings reveal some remarkable results. Exploiting reinforcement learning-based adaptive networks improves cooperation when juxtaposed with existing PDGs performed on homogeneous networks. At the same time, the network's topology evolves from homogeneous to heterogeneous states. This change occurs as players gain experience from past games and become more astute in deciding whether to join PDGs with their current neighbors or disconnect from the least profitable neighbors. Instead, they seek out more favorable environments by establishing connections with second-order neighbors with higher rewards. By calculating the degree distribution and modularity of the adaptive network in a steady state, we confirm that the adaptive network follows a power law and has a clear community structure, indicating that the adaptive network is similar to networks in the real world. Our study reports a new phenomenon in evolutionary game theory on networks. It proposes a new perspective to generate scale-free networks, which is generating scale-free networks by the evolution of homogeneous networks rather than typical ways of network growth and preferential connection. Our results provide new aspects to understanding the network structure, the emergence of cooperation, and the behavior of actors in nature and society. [ABSTRACT FROM AUTHOR]

The main goal of this paper is to study how a decision-making rule for vaccination can affect epidemic spreading by exploiting the Bush–Mosteller (BM) model, one of the methodologies in reinforcement learning in artificial intelligence (AI), which can realize the systematic process of learning in humans, on complex networks. We consider the BM model with two stages—vaccination and epidemiological processes—and address two independent rules about fixed loss consideration and average payoff of neighbors to update agent's vaccination behavior for various stimuli, such as loss of payoffs and environments during the vaccination process. Higher sensitivity not only favors higher vaccination coverage rates but also delays the transition point in relative vaccination costs when transitioning from full vaccination (inoculation level 1) to incomplete vaccination (inoculation level less than 1). Extensive numerical simulations demonstrate that the vaccination dilemma can be overcome to some extent, and the distribution of the intended vaccination probabilities in both independent rules is either normal or skewed when different parameters are considered. Since AI is contributing to many fields, we expect that our BM-empowered learning can ultimately resolve the vaccination dilemma. [ABSTRACT FROM AUTHOR]

COVID-19 has brought a great challenge to the medical system. A key scientific question is how to make a balance between home quarantine and staying in the hospital. To this end, we propose a game-based susceptible-exposed-asymptomatic -symptomatic- hospitalized-recovery-dead model to reveal such a situation. In this new framework, time-varying cure rate and mortality are employed and a parameter m is introduced to regulate the probability that individuals are willing to go to the hospital. Through extensive simulations, we find that (1) for low transmission rates (β < 0.2), the high value of m (the willingness to stay in the hospital) indicates the full use of medical resources, and thus the pandemic can be easily contained; (2) for high transmission rates (β > 0.2), large values of m lead to breakdown of the healthcare system, which will further increase the cumulative number of confirmed cases and death cases. Finally, we conduct the empirical analysis using the data from Japan and other typical countries to illustrate the proposed model and to test how our model explains reality. [ABSTRACT FROM AUTHOR]

An automatic rice-filling device for lotus root with glutinous rice was developed based on the process of artificial filling. In order to find the best parameters for the vibrating rice-filling device—feeding speed, filling height, funnel diameter, amplitude, and frequency—so as to reduce the time and improve the mass of rice filling, EDEM software (EDEM 2022) was used to conduct numerical simulation of the process and analyze the influence of various factors on the rice-filling time. The optimal combination of parameters for the highest quality of rice filling was determined as follows: rice feeding speed, 1.4 kg/s; height of rice filling, 30 mm; funnel diameter, 55 mm; amplitude, 0.6 mm; frequency, 50 Hz; and filling time, 3.4 s. The simulation experiment results are in good agreement with the prototype experiment, achieving the purpose of improving the efficiency of rice filling. This study provides theoretical guidance for research on an automatic rice-filling device for lotus root with glutinous rice. [ABSTRACT FROM AUTHOR]

Recognizing surrounding situations, such as enemy attacks, which can be realized by predator–prey relationships, is one of the common behaviors of the population in ecosystems. In this paper, we explore the relationship between such species' behavior and biodiversity in the spatial rock–paper–scissors game by employing the ecological concept "vigilance." In order to describe the vigilance process, we adopt a multiplex structure where two distinct layers describe virtual and physical interactions. By investigating the process of evolution in species, we also found that species with different vigilance go together. In addition, by utilizing the dynamic time warping method, we found that species with the same vigilance have consistent behavior, but species with different vigilance have diverse behavior. Our findings may lead to broader interpretations of mechanisms promoting biodiversity via vigilance in species ecosystems. [ABSTRACT FROM AUTHOR]

We investigate evolving dynamics of cyclically competing species on spatially extended systems with considering a specific region, which is called the "wildlife refuge," one of the institutional ways to preserve species biodiversity. Through Monte-Carlo simulations, we found that the refuge can play not groundbreaking but an important role in species survival. Species coexistence is maintained at a moderate mobility regime, which traditionally leads to the collapse of coexistence, and eventually, the extinction is postponed depending on the competition rate rather than the portion of the refuge. Incorporating the extinction probability and Fourier transform supported our results in both stochastic and analogous ways. Our findings may provide valuable evidence to assist fields of ecological/biological sciences in understanding the presence and construction of refuges for wildlife with associated effects on species biodiversity. [ABSTRACT FROM AUTHOR]

For analyzing ejector's performance in the system, an ejector for a 10 kW polymer electrolyte membrane fuel cell (PEMFC) system was first designed, manufactured, and a 10 kW PEMFC system bench was built up. A proportional valve and PI pressure feedback control method were adopted to control the hydrogen supply and anode inlet pressure. During the test, performances between dead-ended anode (DEA) mode and ejector mode were compared. Ejector's performances in the system, i.e., volume flow recirculated ratio, difference pressure, dynamic responses of primary pressure, anode inlet pressure, and recirculated gas flow rate during the purge process and current variation condition, were investigated. The results show that pressure adjustment is accurate, continuous, and fast using the proportional valve and PI pressure feedback control method. The hydrogen consumption rate in the ejector mode can reduce from 5% to 10% compared with the rate in the DEA mode except for the stack current 5 A and 10 A conditions. For better water removal out of the anode channel in ejector mode, the maximum stack power increases from 5.11 kW (DEA mode) to 9.56 kW (ejector mode). Anode pressure surge caused by the purge valve switching enhances the ejector's recirculated performance significantly. • An ejector for a 10 kW PEMFC system is designed, manufactured and evaluated. • The stack in ejector's mode shows a better performance than that in DEA mode. • Hydrogen recirculation can reduce the hydrogen consumption. • The proportional valve with the PI pressure feedback method can accurately control the anode inlet pressure. • Anode pressure surge can enhance ejector's recirculated performance. [ABSTRACT FROM AUTHOR]

Distributions of water and oxygen concentration are the two main factors that influence the consistency of current density in a polymer electrolyte membrane fuel cell. While the former type is relevant to the ohmic loss, the latter one associated with the mass transfer loss. In a self-humidified condition, higher demand for water management is requested as membrane drying often appears. To investigate the effects of flow pattern and hydrogen recirculation on the consistency of current density, the cell is tested under five different conditions, and a quasi-three-dimensional transient non-isothermal model is developed to explain different experimental phenomena in this study. Differences of distributions of current density, resistance and reaction gases are examined by comparing co-flow with counter-flow conditions, humidified with self-humidified conditions and dead-ended anode with hydrogen recirculation conditions. The results show that consistency reduces with the cell current density increasing, and gas humification is significantly beneficial. In co-flow configurations, the standard deviation of local current density increases from 0.02 at 0.2 A cm−2 to 0.14 at 1.2 A cm−2 under the humidified condition, increasing from 0.38 at 0.2 A cm−2 to 0.26 at 1.2 A cm−2 under the self-humidified condition. The water distribution of the cell in counter-flow configuration is more uniform than that in the co-flow configuration under the whole current density conditions. Hydrogen recirculation can improve the water content of segments near the inlet gas channel in the anode, and the consistency is the best when the current density is larger than 0.4 A cm−2. • A segmented single cell model is developed. • It has a higher demand for water management in a self-humidified condition. • Consistency in counter-flow configuration is better than that in co-flow way. • Recycled vapor in anode can improve consistency of local current density. [ABSTRACT FROM AUTHOR]

• Lupus-prone mouse has endothelial dysfunction. • RORα is decreased in aorta of lupus-prone mouse and in SLE medium treated HUVECs. • Melatonin prevents endothelial dysfunction in SLE by activating RORα. Atherosclerotic cardiovascular disease confers significant morbidity and mortality in patients with systemic lupus erythematosus (SLE). A substantial proportion of patients with SLE display accelerated endothelial dysfunction, which precedes cardiovascular disease. Melatonin and its nuclear receptor retinoid-related orphan receptor alpha (RORα) have been reported to have some protective effects on the development of atherosclerosis. However, the function of melatonin in SLE-induced endothelial dysfunction and the role that RORα plays are still unknown. In this study, we found that RORα protein expression was decreased in aortas of lupus-prone mice and in human umbilical vein endothelial cells (HUVECs) cultured with medium containing sera of patients with SLE. Melatonin-treated HUVECs showed a decrease of pro-inflammatory mRNAs [interleukin-1beta (IL-1β), interferon-gamma (IFN-γ), and tumor necrosis factor-alpha (TNF-α)] under the stimulation of SLE medium. Melatonin increased nitric oxide and antioxidant mRNAs (SOD1 , GPX1 , and CAT) and downregulated reactive oxygen species (ROS) level in HUVECs, which may subsequently delay endothelial senescence and promote HUVEC proliferation and repair after injury. Melatonin inhibited SLE medium-induced RAW264.7 macrophage migration. HUVECs pretreated with melatonin expressed less adhesion-related proteins (ICAM-1 and VCAM-1); as a result, these cells adhered to fewer peripheral blood monocytes. In addition, we also showed that the protective effects of melatonin on endothelial cells were largely diminished when RORα was knockdown in HUVECs. In conclusion, by targeting the nuclear receptor RORα, melatonin preserves normal functions of endothelium in SLE by its anti-inflammatory, antioxidant, and anti-senescence effects. RORα may have the potential to become a prophylactic or therapeutic target in preventing endothelial dysfunction and atherosclerotic cardiovascular disease in patients with SLE. [ABSTRACT FROM AUTHOR]

The existence of neutral species carries profound ecological implications that warrant further investigation. In this paper, we study the impact of neutral species on biodiversity in a spatial tritrophic system of cyclic competition, in which the neutral species are identified as the fourth species that may affect the competition process of the other three species under the rock-paper-scissors (RPS) rule. Extensive simulations showed that neutral species can promote coexistence in a high mobility regime within the system. When coexistence occurs, we found that the state can be maintained by two mechanisms: Species can either (i) adhere to traditional RPS rule or (ii) form patches to resist invasion. Our findings might aid in understanding the impact of neutral species on biodiversity in ecosystems.