Evolutionary strategy

  • 文章类型: Journal Article
    传统制造业正处于向低碳创新生产转型的初期,迫切需要低碳创新体系来实现碳中和的目标。为了实现对企业碳排放的有效监管,本文构建了一个企业间的三方演化博弈模型,从动态补贴和税收的角度来看政府和公众。主要结果如下。首先,政府补贴的增加在一定程度上有助于鼓励企业选择低碳创新生产战略,但是更多的补贴并不总是更好的。过度的补贴会增加政府监管的成本,降低政府监管的概率。第二,在静态补贴和税收机制下,三方进化博弈系统不收敛。但是,在动态补贴和税收的情况下,该系统可以迅速收敛到稳定状态。稳定点是企业低碳创新的状况,政府监管,和公众监督。第三,公众的干预和监督可以有效防止政府不当行为和企业过度排放生产的现象。而公共奖惩的影响对政府比对企业更有效。
    Traditional manufacturing industry is in the early stages of transition to low-carbon innovative production, and is in urgent need of a low-carbon innovation system to achieve the goal of carbon neutrality. In order to realize the effective supervision of enterprise carbon emissions, this paper constructs a tripartite evolutionary game model among the corporate, government and public from the perspective of dynamic subsidies and taxes. The main results are as follows. First, the increase in government subsidies to a certain extent will help encourage companies to choose low-carbon innovative production strategies, but more subsidies are not always better. Excessive subsidies will increase the cost of government regulation and reduce the probability of government regulation. Second, the tripartite evolutionary game system does not converge under the static subsidies and taxes mechanism. But the system could quickly converges to the stable condition under dynamic subsidies and taxes. The stable point is the situation of corporate low-carbon innovation, government regulation, and public supervision. Third, the public intervention and supervision can effectively prevent the phenomenon of government misconduct and enterprises over-emission production. And the influence of public reward and punishment is more effective for the government than for enterprises.
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  • 文章类型: Journal Article
    生物材料表现出复杂的结构-性质关系,这是自然界经过数百万年的进化而设计的。解开这些关系背后的基本物理原理对于创造具有先进功能的生物材料和结构至关重要。蛋壳是一个非凡的例子,它具有精心设计的结构来平衡权衡,因为它提供了机械保护,同时仍然易于孵化。在这项研究中,我们通过实验和模拟相结合,研究了鸡蛋壳在各种加载条件下的基本机械设计原理。蛋壳的独特几何形状和结构在实现机械韧性和易于孵化之间的出色平衡中起着关键作用。阐明了蛋壳膜的作用以调节蛋壳的机械性能以进一步增强这种平衡。此外,基于这些设计原则,提出了基于力学的三指标模型,建议最佳的蛋壳厚度设计,以提高在各种不同大小的禽类物种中的生存能力。生存能力-设计关系对于开发用于运动安全设备和包装行业的改进结构材料具有巨大潜力。重要声明:在这项研究中揭示了生物材料中复杂的结构-性质关系的基本物理原理,以特别关注鸡蛋壳为例。通过对其机械设计的调查,我们揭示了蛋壳几何形状和结构在实现韧性和易于孵化之间的平衡的关键作用。具体来说,观察到裂纹静止效应,使蛋壳从内部比从外部更容易破裂。此外,我们探索蛋壳膜对这种平衡的影响,有助于增强蛋壳的机械性能。第一次,我们提出了一个三指数模型,揭示了控制蛋壳厚度演变的基本原理。该模型提出了针对多种鸟类的最佳厚度设计,以提高卵子的生存能力为目标。这些发现可以指导具有先进功能的改进结构材料的开发,在广泛的应用中实现更高的安全性和效率。
    Biological materials exhibit complex structure-property relationships which are designed by nature\'s evolution over millions of years. Unlocking the fundamental physical principles behind these relationships is crucial for creating bioinspired materials and structures with advanced functionalities. The eggshell is a remarkable example with a well-designed structure to balance the trade-off as it provides mechanical protection while still being easy for hatching. In this study, we investigate the underlying mechanical design principles of chicken eggshells under various loading conditions through a combination of experiments and simulations. The unique geometry and structure of the eggshell play a critical role in achieving an excellent balance between mechanical toughness and ease of hatching. The effects of eggshell membranes are elucidated to tune the mechanical properties of the eggshell to further enhance this balance. Moreover, a mechanics-based three-index model is proposed based on these design principles, suggesting the optimal eggshell thickness design to improve survivability across a broad range of avian species with varying egg sizes. The survivability-design relationships hold great potential for the development of improved structural materials for applications in sports safety equipment and the packaging industry. STATEMENT OF SIGNIFICANCE: The fundamental physical principles underlying the complex structure-property relationships in biological materials are uncovered in this study, with a particular focus on chicken eggshells as a prime example. Through the investigation of their mechanical design, we reveal the critical role of eggshell geometry and structure in achieving a balance between toughness and ease of hatching. Specifically, the crack resting effect is observed, making the eggshell easier to break from the inside than from the outside. Additionally, we explore the influence of eggshell membranes on this balance, contributing to the enhancement of the eggshell\'s mechanical properties. For the first time, we propose a three-index model that uncovers the underlying principles governing the evolution of eggshell thickness. This model suggests optimal thickness designs for diverse avian species, with the goal of enhancing egg survivability. These findings can guide the development of improved structural materials with advanced functionalities, enabling greater safety and efficiency in a wide range of applications.
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  • 文章类型: Journal Article
    这项研究的目的是为依赖基于尿素的生物能源的自供电生物传感器的电化学性能创建可靠的预测模型。具体来说,该模型侧重于开发基于汗液中尿素利用的人体能量收集模型,这将使自供电生物传感器的发展成为可能。在这个过程中,在脲酶存在下尿素水解的潜力被用作自供电生物传感器的生物反应。酶促反应产生正电位差,可用于为生物燃料电池(BFC)提供动力,并充当生物传感器的能源。该过程提供了自供电生物传感器作为生物燃料电池(BFC)所需的能量。为此,最初,铂电极被多壁碳纳米管修饰以增加其导电性。在铂电极表面稳定脲酶后,测量过程中产生的电流量。实验的优化设计是基于Taguchi方法进行的,以研究尿素浓度的影响,缓冲液浓度,和pH值对产生的电流。使用通用方程作为预测模型,并使用进化策略计算其系数。此外,有效参数的评估是基于错误率进行的。得到的结果表明,所建立的模型以尿素浓度预测电流,缓冲液浓度,和pH精度高。
    The objective of this study is to create a reliable predictive model for the electrochemical performance of self-powered biosensors that rely on urea-based biological energy sources. Specifically, this model focuses on the development of a human energy harvesting model based on the utilization of urea found in sweat, which will enable the development of self-powered biosensors. In the process, the potential of urea hydrolysis in the presence of a urease enzyme is employed as a bioreaction for self-powered biosensors. The enzymatic reaction yields a positive potential difference that can be harnessed to power biofuel cells (BFCs) and act as an energy source for biosensors. This process provides the energy required for self-powered biosensors as biofuel cells (BFCs). To this end, initially, the platinum electrodes are modified by multi-walled carbon nanotubes to increase their conductivity. After stabilizing the urease enzyme on the surface of the platinum electrode, the amount of electrical current produced in the process is measured. The optimal design of the experiments is performed based on the Taguchi method to investigate the effect of urea concentration, buffer concentration, and pH on the generated electrical current. A general equation is employed as a prediction model and its coefficients calculated using an evolutionary strategy. Also, the evaluation of effective parameters is performed based on error rates. The obtained results show that the established model predicts the electrical current in terms of urea concentration, buffer concentration, and pH with high accuracy.
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  • 文章类型: Journal Article
    人工神经网络(ANN)已被成功训练以执行各种感觉运动行为。相比之下,训练以执行类似行为的尖峰神经元网络(SNN)模型的性能仍然相对次优。在这项工作中,我们旨在通过探索不同学习机制的潜力来实现最佳性能,从而推动SNNs领域的发展。我们使用两种在不同时间尺度上运行的学习机制训练SNN来解决CartPole强化学习(RL)控制问题:(1)与尖峰时间相关的强化学习(STDP-RL)和(2)进化策略(EVOL)。虽然STDP-RL在生物系统中的作用已经确立,其他几种机制,虽然没有完全理解,在体内学习过程中协同工作。重新创建准确的模型来捕获STDP-RL与这些不同的学习机制的相互作用是极其困难的。EVOL是一种替代方法,已成功用于许多研究,以适应模型神经反应性电生理记录和,在某些情况下,用于分类问题。EVOL的一个优点是它可能不需要捕获突触可塑性的所有相互作用成分,因此提供了STDP-RL的更好替代方案。这里,我们比较了每种算法在训练后的性能,这表明EVOL是训练SNN执行感觉运动行为的一种强大方法。我们的建模为RL中的SNN开辟了新的功能,可以作为神经生物学家的测试平台,旨在了解神经元回路中的多时间尺度学习机制和动力学。
    Artificial neural networks (ANNs) have been successfully trained to perform a wide range of sensory-motor behaviors. In contrast, the performance of spiking neuronal network (SNN) models trained to perform similar behaviors remains relatively suboptimal. In this work, we aimed to push the field of SNNs forward by exploring the potential of different learning mechanisms to achieve optimal performance. We trained SNNs to solve the CartPole reinforcement learning (RL) control problem using two learning mechanisms operating at different timescales: (1) spike-timing-dependent reinforcement learning (STDP-RL) and (2) evolutionary strategy (EVOL). Though the role of STDP-RL in biological systems is well established, several other mechanisms, though not fully understood, work in concert during learning in vivo. Recreating accurate models that capture the interaction of STDP-RL with these diverse learning mechanisms is extremely difficult. EVOL is an alternative method and has been successfully used in many studies to fit model neural responsiveness to electrophysiological recordings and, in some cases, for classification problems. One advantage of EVOL is that it may not need to capture all interacting components of synaptic plasticity and thus provides a better alternative to STDP-RL. Here, we compared the performance of each algorithm after training, which revealed EVOL as a powerful method for training SNNs to perform sensory-motor behaviors. Our modeling opens up new capabilities for SNNs in RL and could serve as a testbed for neurobiologists aiming to understand multi-timescale learning mechanisms and dynamics in neuronal circuits.
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  • 文章类型: Journal Article
    病毒基因组中的同义密码子偏倚影响蛋白质翻译和基因表达,这表明同义密码子突变体在影响毒力和进化中起着至关重要的作用。然而,隐性突变形式如何有助于病毒进化仍然难以捉摸。在本文中,我们描述了SenecavirusA(SVA),一种小核糖核酸病毒,利用同义密码子突变来影响其进化,导致病毒向不利环境的适应性进化。构建了全球这些SVA谱系的系统发育树和中值连接(MJ)网络,以揭示SVA三阶段遗传发育簇。此外,我们分析了选定菌株的SVA基因组的密码子偏好,发现SVA可以增加某些氨基酸同义密码子的第三个碱基的GC含量,以增强病毒RNA的适应性进化。我们的结果强调了病毒密码子偏倚的隐性突变对SVA进化的影响,并揭示了以前被低估的SVA进化策略。他们还强调了了解SVA的遗传进化以及SVA如何适应外部压力的不利影响的重要性。
    Synonymous codon bias in the viral genome affects protein translation and gene expression, suggesting that the synonymous codon mutant plays an essential role in influencing virulence and evolution. However, how the recessive mutant form contributes to virus evolvability remains elusive. In this paper, we characterize how the Senecavirus A (SVA), a picornavirus, utilizes synonymous codon mutations to influence its evolution, resulting in the adaptive evolution of the virus to adverse environments. The phylogenetic tree and Median-joining (MJ)-Network of these SVA lineages worldwide were constructed to reveal SVA three-stage genetic development clusters. Furthermore, we analyzed the codon bias of the SVA genome of selected strains and found that SVA could increase the GC content of the third base of some amino acid synonymous codons to enhance the viral RNA adaptive evolution. Our results highlight the impact of recessive mutation of virus codon bias on the evolution of the SVA and uncover a previously underappreciated evolutionary strategy for SVA. They also underline the importance of understanding the genetic evolution of SVA and how SVA adapts to the adverse effects of external stress.
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  • 文章类型: Journal Article
    微生物群落不断暴露于其环境中不可预测的变化。为了在这种动态的栖息地中茁壮成长,微生物已经发展出容易转换表型的能力,导致许多表达各种性状的不同适应的亚群。在进化生物学中,在不可预测的变化环境中进化的表型异质性的特殊情况已被定义为下注对冲。押注对冲是一种风险分散策略,在这种策略中,等基因种群随机(随机)使其表型多样化,通常导致适应不良的个体生殖成功率较低。在特定环境中的这种健身权衡可能在突然的环境转变时具有选择性优势。因此,赌注对冲策略允许种群坚持在非常动态的栖息地,但是有特殊的健身费用。近年来,已经观察到不同微生物的表型异质性的许多例子,一些人建议押注对冲。这里,我们重点介绍了有关各种微生物中押注对冲现象的最新报告,以显示这种策略在微生物领域中的用途。本文分为:传染病>分子和细胞生理学。
    Microbial communities are continuously exposed to unpredictable changes in their environment. To thrive in such dynamic habitats, microorganisms have developed the ability to readily switch phenotypes, resulting in a number of differently adapted subpopulations expressing various traits. In evolutionary biology, a particular case of phenotypic heterogeneity that evolved in an unpredictably changing environment has been defined as bet-hedging. Bet-hedging is a risk-spreading strategy where isogenic populations stochastically (randomly) diversify their phenotypes, often resulting in maladapted individuals that suffer lower reproductive success. This fitness trade-off in a specific environment may have a selective advantage upon the sudden environmental shift. Thus, a bet-hedging strategy allows populations to persist in very dynamic habitats, but with a particular fitness cost. In recent years, numerous examples of phenotypic heterogeneity in different microorganisms have been observed, some suggesting bet-hedging. Here, we highlight the latest reports concerning bet-hedging phenomena in various microorganisms to show how versatile this strategy is within the microbial realms. This article is categorized under: Infectious Diseases > Molecular and Cellular Physiology.
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  • 文章类型: Journal Article
    Viruses are known to have some of the highest and most diverse mutation rates found in any biological replicator, with single-stranded (ss) RNA viruses evolving the fastest, and double-stranded (ds) DNA viruses having rates approaching those of bacteria. As mutation rates are tightly and negatively correlated with genome size, selection is a clear driver of viral evolution. However, the role of intragenomic interactions as drivers of viral evolution is still unclear. To understand how these two processes affect the long-term evolution of viruses infecting humans, we comprehensively analyzed ssRNA, ssDNA, dsRNA, and dsDNA viruses, to find which virus types and which functions show evidence for episodic diversifying selection and correlated evolution. We show that selection mostly affects single stranded viruses, that correlated evolution is more prevalent in DNA viruses, and that both processes, taken independently, mostly affect viral replication. However, the genes that are jointly affected by both processes are involved in key aspects of their life cycle, favoring viral stability over proliferation. We further show that both evolutionary processes are intimately linked at the amino acid level, which suggests that it is the joint action of selection and correlated evolution, and not just selection, that shapes the evolutionary trajectories of viruses-and possibly of their epidemiological potential.
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  • 文章类型: Journal Article
    Backward or subcritical bifurcation is usually considered an undesirable phenomenon in epidemiology since control measures require a reduction in R0 not below one but below a much smaller value. However, there are contexts for which a backward or subcritical bifurcation is not a bad thing; it can even be desirable. Such is the case for any characteristic that can be passed to the next generation (genetically fixed or not) and that increases the effective reproductive rate of the host or the total number of individuals. In the present work, we study an epidemiological model consisting of two classes, susceptible and \"infected\" individuals; the model considers a characteristic that is passed from \"infected\" to \"susceptible\" by direct \"contact,\" for instance increased fecundity. We analyze conditions for the appearance of a backward or subcritical bifurcation. We discuss the advantage for the population under infection, since the total number of individuals increases at equilibrium. If one takes that as a proxy for increased fitness, it would increase the species\' ecological success. One key element in the model is the fact that \"susceptible\" individuals have \"susceptible\" descendants, but \"infected\" individuals can have \"infected\" descendants as well as \"susceptible\" ones. A somehow rare addition for epidemiological models, the fact that \"infected\" individuals reproduce more rapidly than the susceptible ones, leads to unexpected consequences. Facilitating the \"inoculation\" increases the total population size, i.e., the backward or subcritical bifurcation appears, with desirable consequences for the population. We show that an increase in the number of susceptible newborns is the main reason for the appearance of a backward or subcritical bifurcation, which induces a bigger population size. We analyze the effect of different combinations of susceptible/infected birth rates. This kind of phenomenon has been observed for bacterial infections in several insects-bacteria and nematodes-bacteria interactions; in particular, it has been intensely studied in interactions of wasps and flies with the genus Wolbachia. It has also been shown in amphibians.
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  • 文章类型: Journal Article
    UNASSIGNED: A profile-comparison method with position-specific scoring matrix (PSSM) is among the most accurate alignment methods. Currently, cosine similarity and correlation coefficients are used as scoring functions of dynamic programming to calculate similarity between PSSMs. However, it is unclear whether these functions are optimal for profile alignment methods. By definition, these functions cannot capture nonlinear relationships between profiles. Therefore, we attempted to discover a novel scoring function, which was more suitable for the profile-comparison method than existing functions, using neural networks.
    UNASSIGNED: Although neural networks required derivative-of-cost functions, the problem being addressed in this study lacked them. Therefore, we implemented a novel derivative-free neural network by combining a conventional neural network with an evolutionary strategy optimization method used as a solver. Using this novel neural network system, we optimized the scoring function to align remote sequence pairs. Our results showed that the pairwise-profile aligner using the novel scoring function significantly improved both alignment sensitivity and precision relative to aligners using existing functions.
    UNASSIGNED: We developed and implemented a novel derivative-free neural network and aligner (Nepal) for optimizing sequence alignments. Nepal improved alignment quality by adapting to remote sequence alignments and increasing the expressiveness of similarity scores. Additionally, this novel scoring function can be realized using a simple matrix operation and easily incorporated into other aligners. Moreover our scoring function could potentially improve the performance of homology detection and/or multiple-sequence alignment of remote homologous sequences. The goal of the study was to provide a novel scoring function for profile alignment method and develop a novel learning system capable of addressing derivative-free problems. Our system is capable of optimizing the performance of other sophisticated methods and solving problems without derivative-of-cost functions, which do not always exist in practical problems. Our results demonstrated the usefulness of this optimization method for derivative-free problems.
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  • 文章类型: Journal Article
    The ability to navigate is a hallmark of living systems, from single cells to higher animals. Searching for targets, such as food or mates in particular, is one of the fundamental navigational tasks many organisms must execute to survive and reproduce. Here, we argue that a recent surge of studies of the proximate mechanisms that underlie search behavior offers a new opportunity to integrate the biophysics and neuroscience of sensory systems with ecological and evolutionary processes, closing a feedback loop that promises exciting new avenues of scientific exploration at the frontier of systems biology.
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