Redox‐Active Organic Compounds for Future Sustainable Energy Storage System

Utilizing redox‐active organic compounds for future energy storage system (ESS) has attracted great attention owing to potential cost efficiency and environmental sustainability. Beyond enriching the pool of organic electrode materials with molecular tailoring, recent scientific efforts demonstrate the innovations in various cell chemistries and configurations. Herein, recent major strategies to build better organic batteries, are highlighted: diversifying charge‐carrying ions, modifying electrolytes, and utilizing liquid‐type organic electrodes. Each approach is summarized along with their advantages over Li‐ion batteries (LIBs). An outlook is also provided on the practical realization of organic battery systems, which hints at possible solutions for future sustainable ESSs.     

Bounds on the number of ESSs of a matrix game

It is well known that for any evolutionary game there may be more than one evolutionarily stable strategy (ESS). In general, the more ESSs there are, the more difficult it is to work out how the population will behave (unless there are no ESSs at all). If a matrix game has an ESS which allows all possible pure strategies to be played, referred to as an internal ESS, then no other ESS can exist. In fact, the number of ESSs possible is highly dependent upon how many of the pure strategies each allow to be played, their support size. It is shown that if alpha is the ratio of the mean support size to the number of pure strategies n, then as n tends to infinity the greatest number of ESSs can be represented by a continuous function f(alpha) with useful regularity properties, and bounds are found for both f(alpha) and the value alpha(*), where it attains its maximum. Thus we can obtain a limit on the complexity of any particular system as a function of its mean support size.     

Systematic identification and analysis of exonic splicing silencers

Exonic splicing silencers (ESSs) are cis-regulatory elements that inhibit the use of adjacent splice sites, often contributing to alternative splicing (AS). To systematically identify ESSs, an in vivo splicing reporter system was developed to screen a library of random decanucleotides. The screen yielded 141 ESS decamers, 133 of which were unique. The silencer activity of over a dozen of these sequences was also confirmed in a heterologous exon/intron context and in a second cell type. Of the unique ESS decamers, most could be clustered into groups to yield seven putative ESS motifs, some resembling known motifs bound by hnRNPs H and A1. Potential roles of ESSs in constitutive splicing were explored using an algorithm, ExonScan, which simulates splicing based on known or putative splicing-related motifs. ExonScan and related bioinformatic analyses suggest that these ESS motifs play important roles in suppression of pseudoexons, in splice site definition, and in AS.     

Models of parent-offspring conflict. IV. Suppression: Evolutionary retaliation by the parent

We have earlier analysed ESSs for the amount of parental investment (PI) that offspring are expected to solicit from their parents, given that parents acquiesce to offspring demands. The present paper considers evolutionary retaliation by the parent for species where only one parent provides PI. Two genetic loci are envisaged: one (the ‘conflictor’ locus) determines the extent of offspring solicitation; the other (the ‘suppressor’ locus) determines how parents retaliate. Solicitation is assumed to carry a cost which may affect a particular offspring uniquely if time and energy are the major costs, or may affect all offspring in a brood equally if the main cost is predation risk. Two kinds of parental retaliation are possible. Parents may supply PI in proportion to offspring demands, or may ignore solicitation altogether and give a fixed PI. Analytical models of conflict in which the parent supplies PI in proportion to solicitation yield pure ESSs with PI at a compromise level between parent and offspring interests. These are termed ‘pro rata’ ESSs. Where solicitation costs are high, an ‘offspring wins’ ESS (offspring get all they ‘want’) is possible especially for forms of conflict that affect future sibs, and a ‘parent wins’ ESS (parent supplies its optimum) is possible especially for conflict that affects contemporary sibs. When parental retaliation takes the form of ignoring offspring solicitation, this can lead to a ‘parent wins’ ESS if costs of ignoring solicitation are negligible, but where parental insensitivity carries costs, the result is an unresolvable evolutionary chase with cycling frequencies of alleles coding for parent and offspring strategies. ‘Pro rata’ ESSs cannot be invaded by ‘ignore solicitation’ mutants but ‘pro rata’ mutants can often invade at certain stages in ‘ignore solicitation’ limit cycles. We therefore conclude that the probable evolutionary end product for most species will be the ‘pro rata’ ESS in which the parent supplies more PI than would be optimal in the absence of conflict, but less PI than would be an ESS for the offspring in the absence of parental retaliation. Such ESSs will be characterized by solicitation costs; offspring will ‘ask’ for more PI than they get. In nature, under similar conditions, highest conflict will occur when both parents sustain equally the effects of conflict, or when conflict affects contemporary rather than future sibs.     

Nash equilibrium and evolutionary stability in large- and finite-population "playing the field" models

This paper studies the correspondence between Nash equilibrium and evolutionary stability in large- and finite-population "playing the field" models. Whenever the fitness function is sufficiently continuous, any large-population ESS corresponds to a symmetric Nash equilibrium in the game that describes the simultaneous interaction of the individuals in the population, and any strict, symmetric Nash equilibrium in that game corresponds to a large-population ESS. This correspondence continues to hold, approximately, in finite populations; and it holds exactly for strict pure-strategy equilibria in sufficiently large finite populations. By contrast, a sequence of (mixed-strategy) finite-population ESSs can converge, as the population grows, to a limit that is not a large-population ESS, and a large-population ESS need not be the limit of any sequence of finite-population ESSs.     

General and specific functions of exonic splicing silencers in splicing control

Correct splice site recognition is critical in pre-mRNA splicing. We find that almost all of a diverse panel of exonic splicing silencer (ESS) elements alter splice site choice when placed between competing sites, consistently inhibiting use of intron-proximal 5' and 3' splice sites. Supporting a general role for ESSs in splice site definition, we found that ESSs are both abundant and highly conserved between alternative splice site pairs and that mutation of ESSs located between natural alternative splice site pairs consistently shifted splicing toward the intron-proximal site. Some exonic splicing enhancers (ESEs) promoted use of intron-proximal 5' splice sites, and tethering of hnRNP A1 and SF2/ASF proteins between competing splice sites mimicked the effects of ESS and ESE elements, respectively. Further, we observed that specific subsets of ESSs had distinct effects on a multifunctional intron retention reporter and that one of these subsets is likely preferred for regulation of endogenous intron retention events. Together, our findings provide a comprehensive picture of the functions of ESSs in the control of diverse types of splicing decisions.     

On the war of attrition and other games among kin

Evolutionarily stable strategies or ESSs of games among kin have been calculated in the literature by both personal-fitness and inclusive-fitness methods. These methods were compared by Hines and Maynard Smith (1979) for games with bilinear payoffs. Although Hines and Maynard Smith regarded the first method as correct, they regarded the second method as useful because the inclusive-fitness conditions for an ESS gave necessary conditions for a personal-fitness ESS in the class of games they considered. In general, however, satisfying the inclusive-fitness conditions is neither necessary nor sufficient for satisfying the personal-fitness conditions, although the two methods may often yield identical ESSs. This result is established by reformulating the classic war-of-attrition model to allow variation in energy reserves, assumed to have a Gamma distribution. For this game, the two methods may disagree for intermediate values of relatedness. By the correct method, if the coefficient of variation in energy reserves is sufficiently high, then the game has a unique ESS in pure strategies at which populations with higher coefficients of variation or relatedness display for shorter times. Unrelated contestants are prepared to expend at least half of their reserves. For populations with lower variation coefficients, the ESS exists only if the cost of displaying per unit time is low compared to the rate at which remaining reserves translate into expected future reproductive success for the victor. The critical variation coefficient, below which the ESS exists regardless of cost, decreases from 0.52 to 0 as the coefficient of relatedness increases from 0 to 1. Although there is no assessment, contests are always won by the animal with greater energy reserves in a population at the ESS.     

Recent Progress in Electrode Materials for Sodium‐Ion Batteries

Grid‐scale energy storage systems (ESSs) that can connect to sustainable energy resources have received great attention in an effort to satisfy ever‐growing energy demands. Although recent advances in Li‐ion battery (LIB) technology have increased the energy density to a level applicable to grid‐scale ESSs, the high cost of Li and transition metals have led to a search for lower‐cost battery system alternatives. Based on the abundance and accessibility of Na and its similar electrochemistry to the well‐established LIB technology, Na‐ion batteries (NIBs) have attracted significant attention as an ideal candidate for grid‐scale ESSs. Since research on NIB chemistry resurged in 2010, various positive and negative electrode materials have been synthesized and evaluated for NIBs. Nonetheless, studies on NIB chemistry are still in their infancy compared with LIB technology, and further improvements are required in terms of energy, power density, and electrochemical stability for commercialization. Most recent progress on electrode materials for NIBs, including the discovery of new electrode materials and their Na storage mechanisms, is briefly reviewed. In addition, efforts to enhance the electrochemical properties of NIB electrode materials as well as the challenges and perspectives involving these materials are discussed.     

Simulating natural selection as a culling mechanism on finite populations with the hawk-dove game

The behaviors of individuals and species are often explained in terms of evolutionary stable strategies (ESSs). The analysis of ESSs determines which, if any, combinations of behaviors cannot be invaded by alternative strategies. Two assumptions required to generate an ESS (i.e., an infinite population and payoffs described only on the average) do not hold under natural conditions. Previous experiments indicated that under more realistic conditions of finite populations and stochastic payoffs, populations may evolve in trajectories that are unrelated to an ESS, even in very simple games. The simulations offered here extend earlier research by employing truncation selection with random parental selection in a hawk-dove game. Payoffs are determined in pairwise contests using either the expected outcome, or the result of a random variable. In each case, however, the mean fraction of hawks over many generations and across many independent trials does not conform to the expected ESS. Implications of these results and philosophical underpinnings of ESS theory are offered.     

Compromised strategy resolves intersexual conflict over pre-copulatory guarding duration

Summary An evolutionarily stable strategy (ESS) on pre-copulatory mate-guarding duration is separately obtained for males and females, by assuming that either the male or female can control perfectly the timing of guarding. A difference between sexes in an ESS brings on an intersexual conflict, in particular when the ESS of the actively searching sex (usually male) is longer than that of the other. We analyse two extreme situations, in which the female mating stages are either perfectly synchronized or uniformly distributed. The analysis reveals that (1) the male ESS for guarding duration is longer than the female ESS in the synchronized case if the sex ratio is male-biased, (2) the difference in ESSs is higher for a more male-biased sex ratio, less guarding costs or a higher encounter rate, and (3) an asynchronous female mating cycle extends the conflict region towards female-biased sex ratios. We show by including conflict costs in fitnesses of both sexes that intersexual conflict may be resolved by a compromised solution, where the starting time of mate guarding is an intermediate value between the ESSs of the two sexes. This compromised strategy depends on both fitness increments of winning the conflict and physical power in controlling the opponent and tends to approach the ESS of the commoner sex in highly biased sex ratios. If both actors engaged in a conflict have enough information on each other, a compromise without an overt struggle may be reached.     

Why do some nectar foragers perch and others hover while probing flowers?

Diurnal hawkmoths, Hemaris fuciformis, and bumblebees, Bombus pasquorum, were observed foraging for nectar in flowers of Viscaria vulgaris. The hawkmoths hovered in front of the flowers, while the bees perched on them. The hawkmoths had a faster probing rate than the bees, and consequently also had higher gross and net rates of energy gain. A model is presented that shows that hovering only yields a higher net rate of energy gain (NREG) than perching when nectar volumes are high due to low competition for the resource. The difference in NREG of perchers and hoverers decreases with an increase of competition, and eventually perching yields the highest NREG. This is an effect of the higher cost of hovering. The results suggest that hovering can only evolve as a pure evolutionarily stable strategy (ESS) if competition is reduced, for example by co-evolutionary specializations with plants. The possibility that it has evolved as a mixed ESS (i.e. individuals can both hover and perch depending on the resource level) is discussed. The evolution of optimal foraging strategies is discussed, and it is pointed out that the rate of gain of an animal is independent of the strategy used when all competing foragers use the same strategy, but competitively superior strategies will nevertheless evolve because they are ESSs. Competition between strategies with different energy costs are special, because resource availability determines which strategy is competitively superior. A high-cost strategy can only evolve as a pure ESS at high resource levels, or as a mixed ESS at intermediate levels.     

Maximal ecological diversity exceeds evolutionary diversity in model ecosystems

Understanding community saturation is fundamental to ecological theory. While investigations of the diversity of evolutionary stable states (ESSs) are widespread, the diversity of communities that have yet to reach an evolutionary endpoint is poorly understood. We use Lotka–Volterra dynamics and trait-based competition to compare the diversity of randomly assembled communities to the diversity of the ESS. We show that, with a large enough founding diversity (whether assembled at once or through sequential invasions), the number of long-time surviving species exceeds that of the ESS. However, the excessive founding diversity required to assemble a saturated community increases rapidly with the dimension of phenotype space. Additionally, traits present in communities resulting from random assembly are more clustered in phenotype space compared to random, although still markedly less ordered than the ESS. By combining theories of random assembly and ESSs we bring a new viewpoint to both the saturation and random assembly literature.     

Extended secondary structures in proteins

Supersecondary structures of proteins have been systematically searched and classified, but not enough attention has been devoted to such large edifices beyond the basic identification of secondary structures. The objective of the present study is to show that the association of secondary structures that share some of their backbone residues is a commonplace in globular proteins, and that such deeper fusion of secondary structures, namely extended secondary structures (ESSs), helps stabilize the original secondary structures and the resulting tertiary structures. For statistical purposes, a set of 163 proteins from the protein databank was randomly selected and a few specific cases are structurally analyzed and characterized in more detail. The results point that about 30% of the residues from each protein, on average, participate in ESS. Alternatively, for the specific cases considered, our results were based on the secondary structures produced after extensive Molecular Dynamics simulation of a protein–aqueous solvent system. Based on the very small width of the time distribution of the root mean squared deviations, between the ESS taken along the simulation and the ESS from the mean structure of the protein, for each ESS, we conclude that the ESSs significantly increase the conformational stability by forming very stable aggregates. The ubiquity and specificity of the ESS suggest that the role they play in the structure of proteins, including the domains formation, deserves to be thoroughly investigated.     

ORGANIZATION OF PREDATOR-PREY COMMUNITIES AS AN EVOLUTIONARY GAME

We consider a simple predator-prey model of coevolution. By allowing coevolution both within and between trophic levels the model breaks the traditional dichotomy between coevolution among competitors and coevolution between a prey and its predator. By allowing the diversity of prey and predator species to emerge as a property of the evolutionarily stable strategies (ESS), the model breaks another constraint of most approaches to coevolution that consider as fixed the number of coevolving species. The number of species comprising the ESS is influenced by a parameter that determines the predator's niche breadth. Depending upon the parameter's value the ESS may contain: 1) one prey and one predator species, 2) two prey and one predator, 3) two prey and two predators, 4) three prey and two predators, 5) three prey and three predators, etc. Evolutionarily, these different ESSs all emerge from the same model. Ecologically, however, these ESSs result in very different patterns of community organization. In some communities the predator species are ecologically keystone in that their removal results in extinctions among the prey species. In others, the removal of a predator species has no significant impact on the prey community. These varied ecological roles for the predator species contrasts sharply with the essential evolutionary role of the predators in promoting prey species diversity. The ghost of predation past in which a predator's insignificant ecological role obscures its essential evolutionary role may be a frequent property of communities of predator and prey.     

A two-trial two-strategy conflict

Iterated conflicts allow the possibility of co-operative-like behaviour in games such as the Prisoner's Dilemma. The present paper is an attempt to initiate the study of iterated conflicts when, (a) the number of iterations is fixed and finite and (b) the underlying payoff matrix is general, e.g. a mixed Evolutionary Stable Strategy (ESS) could occur in the non-iterated coflict. These assumptions are in contrast to the Iterated Prisoner's Dilemma. We consider a somewhat special case which none the less produces results of an interesting nature. For those cases where there is no internal ESS in the one trial case the two-trial case is easily resolved. When the former has an internal ESS then the two-trial case yields two ESSs whose supports are a partition of the space of strategies.     

HnRNP L represses exon splicing via a regulated exonic splicing silencer

Skipping of mammalian exons during pre-mRNA splicing is commonly mediated by the activity of exonic splicing silencers (ESSs). We have recently identified a regulated ESS within variable exon 4 of the CD45 gene, named ESS1, that is necessary and sufficient for partial exon repression in resting T cells and has additional silencing activity upon T-cell activation. In this study, we identify three heterogeneous nuclear ribonucleoproteins (hnRNPs) that bind specifically to ESS1. The binding of one of these proteins, hnRNP-L, is significantly decreased by mutations that disrupt both the basal and induced activities of ESS1. Recombinant hnRNP-L functions to repress exon inclusion in vitro in an ESS1-dependent manner. Moreover, depletion of hnRNP-L, either in vitro or in vivo, leads to increased exon inclusion. In contrast, the other ESS1-binding proteins, PTB and hnRNP E2, do not discriminate between wild-type and mutant ESS1 in binding studies, and do not specifically alter ESS1-dependent splicing in vitro. Together, these studies demonstrate that hnRNP-L is the primary protein through which CD45 exon 4 silencing is mediated by the regulatory sequence ESS1.     

Evolutionarily stable sets in symmetric extensive two-person games.

Evolutionarily stable (ES) sets are characterized for evolutionary games in extensive form. It is shown that, for the normal form of games involving informational symmetries or repeated play, the standard approach of determining evolutionarily stable strategies (ESSs) often fails to predict the evolutionary outcome. The dynamic stability of ES sets is proved in both the pure strategy and mixed strategy models. ES sets are shown to also generalize the notion of direct ESSs (an earlier attempt to apply ESS theory to extensive games). The theory is illustrated by three examples of biological games in extensive form.     

Are there really no evolutionarily stable strategies in the iterated prisoner's dilemma?

The evolutionary form of the iterated prisoner's dilemma (IPD) is a repeated game where players strategically choose whether to cooperate with or exploit opponents and reproduce in proportion to game success. It has been widely used to study the evolution of cooperation among selfish agents. In the past 15 years, researchers proved over a series of papers that there is no evolutionarily stable strategy (ESS) in the IPD when players maintain long-term relationships. This makes it difficult to make predictions about what strategies can actually persist as prevalent in a population over time. Here, we show that this no ESS finding may be a mathematical technicality, relying on implausible players who are "too perfect" in that their probability of cooperating on any move is arbitrarily close to either 0 or 1. Specifically, in the no ESS proof, all strategies were allowed, meaning that after a strategy X experiences any history H, X cooperates with an unrestricted probability p (X, H) where 0< or =p (X, H)< or =1. Here, we restrict strategies to the set S in which X is a member of S [corrected] if after any H, X cooperates with a restricted probability p (X, H) where e< or =p (X, H)< or =1-e and 0相似文献   

Genetical ESS-models. I. Concepts and basic model

Evolutionarily Stable Strategies (ESS) in phenotypic models are used to explain the evolution of animal interactive behaviour. As the behavioural features under consideration are assumed to be genetically determined, the question arises how underlying a genetical system might affect the results of phenotypic ESS-models. This question can be fully treated in terms of ESS-theory. A method of designing Genetical ESS-Models is proposed, which transfers the question of evolutionary stability to a "lower" level, the genetical basis. Genetical ESS-models - although nonlinear even in the simplest cases - can be analysed in a way that is familiar to ESS-theorists and yield immediate results on gene pool ESSs, which then may or may not maintain ESSs on the phenotypic level. Moreover, general results can be obtained to characterize evolutionarily stable gene pool states and their interrelation with commonsense, phenotypic ESSs. This part of the article presents the basic concepts and an outline of the method of genetical ESS-models. It gives, as a demonstration, a complete analysis for phenotypic two-strategy models (linear or nonlinear) based on a diploid, diallelic single-locus system under random mating. The results in this case suggest that a phenotypic ESS should indeed be expected to evolve but, maybe, only after passing through a succession of temporarily stable states.     

The evolution of aggressive losers

We examine the question of when aggressive behavior of likely losers should be part of an evolutionarily stable strategy. We modified an earlier model by the authors that found situations where likely losers initiate aggressive interactions more often than likely winners. The modifications allowed us to examine the robustness of the previous study by including an unusually high number of possible strategies (n=81) and to examine a wide range of parameter settings. First, we show that restricting attention to only a few most plausible strategies may change the overall results. Second, within the space where escalation is predicted, for a large percentage of the parameter settings (85%), an ESS exists that leads to a somewhat counterintuitive situation where escalation is more often initiated by the likely loser than by the likely winner of the contest. In contrast, an ESS that favors escalation by likely winners was found only for about 3% of parameter settings. Furthermore, we use simulations of evolution in a finite population to verify for certain parameter settings that the analytically predicted ESS's could in fact evolve. Our results suggest that ESSs in which the likely loser rather than the likely winner is expected to initiate escalation are generic and ESSs in which the opposite is true need to be explained by incorporating specific features of the biology of a given species into more detailed models.