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Millions of employees around the world work in irregular rosters. The quality of these rosters is of utmost importance. High-quality rosters should be attractive on an individual level, but also divide the work fairly over the employees. We develop novel methodology to compute the trade-off between fairness and attractiveness in crew rostering. First, we propose an intuitive fairness scheme for crew rostering and analyze its theoretical performance. To do so, we introduce the approximate resource-allocation problem. This extension of the resource-allocation problem provides a framework for analyzing decision making in contexts where one relies on approximations of the utility functions. Fairness is a typical example of such a context due to its inherently subjective nature. We show that the scheme has “optimal” properties for a large class of approximate utility functions. Furthermore, we provide a tight bound on the utility loss for this scheme. We then present a unified approach to crew rostering. This approach integrates our proposed fairness scheme with a novel mathematical formulation for crew rostering. We call the resulting problem the Fairness-Oriented Crew Rostering Problem and develop a dedicated exact Branch-Price-and-Cut solution method. We conclude by applying our solution approach to practical instances from Netherlands Railways, the largest passenger railway operator in the Netherlands. Our computational results confirm the importance of taking the fairness–attractiveness trade-off into account. This paper was accepted by Yinyu Ye, optimization.

There is much variation in ownership concentration among entrepreneurial firms cross-sectionally and over time. Growth potential, risk-sharing, and demand for external capital seem to be the main reasons behind the choice of low ownership concentration, and firms with diluted ownership show strong growth. After controlling for the firm fixed effects or the sample selection bias, we do not find any evidence suggesting a link between ownership concentration and other dimensions of firm performance. Therefore, the trade-off between growth aspiration and retention of dominant control of the firms may be critical in ownership structure decisions among entrepreneurial firms.

In many insect taxa, there is a well‐established trade‐off between flight capability and reproduction. The wing types of Acridoidea exhibit extremely variability from full length to complete loss in many groups, thus, provide a good model for studying the trade‐off between flight and reproduction. In this study, we completed the sampling of 63 Acridoidea species, measured the body length, wing length, body weight, flight muscle weight, testis and ovary weight, and the relative wing length (RWL), relative flight muscle weight (RFW), and gonadosomatic index (GSI) of different species were statistically analyzed. The results showed that there were significant differences in RWL, RFW, and GSI among Acridoidea species with different wing types. RFW of long‐winged species was significantly higher than that of short‐winged and wingless species (p, Flight‐capable individuals (long‐winged) of Acridoidea expend energy developing and maintaining the flight apparatus at the expense of reproduction. Flight‐incapable individuals (short‐winged or wingless) cannot fly, but has a greater reproductive output. The results provide evidence for the trade‐off between flight and reproduction in Acridoidea.

International audience; Multiple infections, either simultaneous or sequential, affecting a single plant or crop are now recognized to be common in plant disease epidemics. These multiple infections thus generate a range of competitive interactions (exploitation competition, apparent competition, or interference competition) that directly impact competitors' life history traits, and hence fitness. While a theoretical framework, based primarily on three ecological theories-niche exclusion, the "tragedy of the commons", and the virulence-transmission trade-off, provides insights into potential outcomes of multiple infections on pathogen evolution and virulence and on disease dynamics, experimental observations, although rather rare so far, strongly suggest that unexpected outputs can also occur. This review therefore attempts to provide a comprehensive overview of both theoretical and empirical knowledge about multiple infection in plants. It highlights the need for a detailed assessment of pathogen life history traits and their modulation according to competition types, host receptivity, and pathogen life strategies for a better understanding and prediction of the evolutionary and demographic outcomes of multiple infections, as well as research questions still open in this emerging field of plant pathology.

This paper proposes a vector error correction model to investigate the relationship between polluting emissions and GDP levels in Japan, in the period 1970-2014, and tests the validity of the Environmental Kuznets Curve (EKC) hypothesis driven by tourist arrivals. Our results validate the existence of two different causality channels among the selected variables. In particular, we find that a trade-off might exist between increasing the number of tourists, which drives economic growth, and the pattern of a sustainable development, due to the increase of polluting emissions. The analysis allows us to propose appropriate policy strategies to promote a robust and sustainable long run economic growth.

Eusocial insect societies possess complex multilevel disease defences, including individual level protection conferred by physical (e.g. cuticle) and immunological obstacles and colony level protection mediated by collective behaviours (social immunity). It remains unclear whether and how these two levels of disease protection are related to one another in jointly driving colonies’ susceptibility to disease. Here, we examine whether a relationship exists between individual worker survival after exposure to a fungal pathogen (a proxy for immunity) and corpse removal (a colony level social immunity metric) in the acorn ant Temnothorax curvispinosus. Since behavioural avoidance is the first line of defence against infection, we also tested whether individual ants exhibited parasite avoidance behaviour during exploration and whether colonies exhibit avoidance behaviour during foraging. We found that individual level and colony level immunity were negatively correlated: colonies that removed corpses more rapidly contained workers with weaker individual defences. We did not detect parasite avoidance behaviour by individual workers or whole colonies, nor were these two factors related. These data suggest that individual immunity and social immunity may trade off, regulating overall parasite protection. Alternatively, optimized social immunity at the colony level may compensate for disease vulnerability to infection at the individual level, and thus provide a protective benefit in overall colony defence in the absence of pathogen avoidance.

The proximate and ultimate mechanisms behind individual behavioural phenotypes are still only partially understood, with studies often focusing on a single or a few factor(s) that affect behaviour in a controlled environment. To understand the development and consequences of individual behavioural phenotypes in their complexity, a comprehensive approach is needed that analyses the effects of a broad spectrum of factors and their interactions on behaviour within the natural environment. We used focal observations to quantify four key behavioural components of Gala = pagos sea lion, Zalophus wollebaeki, pups under natural conditions: general social interactions, swimming, resting and social play behaviour. We then investigated the influence and interplay of age, sex, body condition, basal cortisol and testosterone levels, personality scores and the social environment on the observed behaviour. We identified significant correlations between all measured factors and behaviour. Complex interactions between testosterone, boldness and social play especially stand out, with the effect of boldness on social play being dependent on testosterone levels. We also demonstrate the importance of the early social environment, defined as local population density, for social play and, interestingly, time spent swimming. This could have consequences for the development of social and hunting skills, crucial for later stages of ontogeny. For this endangered pinniped, a decline in the diversity of social environments due to dwindling population numbers could lead to a decline in behavioural diversity and lower coping abilities towards future changes in their environment. Our study reveals important factors for the development of individual behavioural phenotypes of young Gala = pagos sea lions and elucidates some aspects of the architecture behind this individual variation in behaviour. (c) 2021 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.

Pandemics attack the primary asset (labor) of peasant households and the rural poor. Peasant households must simultaneously allocate labor between farm and household activities, where the demand for agricultural labor is seasonal, which limits intra-temporal substitution, without perfect foresight. A pandemic reduces the supply of labor, through deaths and morbidity, with the scale of reductions in labor supply depending on the seasons in which a pandemic occurs. The analyses, using a recursive dynamic economy-wide model for Bhutan, demonstrate that outbreaks in high labor demand seasons cause increases in wage rates almost three times as high as for outbreaks in low labor demand seasons. Increases in wage rates induce peasant households to reallocate labor time between farm and household activities through the labor-leisure trade-off mechanism. Such changes in the allocation of labor time are important elements of peasants’ mitigation responses, and can reduce the negative economic implications of a pandemic. © 2021 The International Input--Output Association.

In this study, we investigated which strategy Macrobrachium amazonicum populations use to survive in river and estuary environments. In each environment, abiotic factors were analyzed in situ, and ovigerous females and males of M. amazonicum specimens were captured. To determine ovarian maturity and morphotypes, gonads were removed and processed histologically, and the gonadosomatic index and condition factor (K) were determined. Ovigerous females were analyzed to determine the relationship between ovarian maturation and the embryonic phases of eggs in the brood pouch. Precipitation, turbidity and dissolved oxygen showed differences between the estuary and river. The population of ovigerous females showed that ovarian maturation was simultaneous with embryonic development. However, the freshwater prawn populations in the river were smaller and consisted of a greater number of ovigerous females with maturing and mature ovaries. In the estuary, ovigerous females with spawned and reorganized ovaries were observed more frequently. In males, the GC morphotype was absent in the river, where the TC morphotype predominated and showed similar reproductive conditions as the GC morphotype in the estuary. M. amazonicum has strategies for allocating energy for reproduction or growth in different environments. This description established the trade-off as a strategy used by M. amazonicum to maintain the population in adverse environments.

Growth and reproduction are two essential life‐history traits for fungi. Understanding life‐history strategies provides insight into the environmental adaption of species. Here, we investigated the colonial morphology, vegetative growth, and asexual reproduction of the ascomycete fungus Bionectria ochroleuca in response to a variety of environmental conditions. We demonstrated that the increased temperature from 15 to 25°C induced mycelial growth and conidiation in B. ochroleuca. We also found that the optimal temperatures for mycelial growth and conidial formation in this fungus species were 25 and 30°C, respectively. However, as the temperature increased from 25 to 30°C, mycelial growth was suppressed, but the total number of conidia was significantly increased. The shift in light–dark cycles dramatically changed the morphological features of the colonies and affected both vegetative growth and asexual reproduction. Under incubation environments of alternating light and dark (16:8 and 8:16 light:dark cycles), conidiophores and conidia in the colonies formed dense‐sparse rings and displayed synchronous wave structures. When the light duration was prolonged in the sequence of 0, 8, 16, and 24 hr per day, mycelial growth was suppressed, but conidiation was promoted. Together, our results indicate that temperature and light period may trigger a trade‐off between vegetative growth and asexual reproduction in B. ochroleuca.

Males have the ability to compete for fertilizations through both precopulatory and postcopulatory intrasexual competition. Precopulatory competition has selected for large weapons and other adaptations to maximize access to females and mating opportunities, while postcopulatory competition has resulted in ejaculate adaptations to maximize fertilization success. Negative associations between these strategies support the hypothesis that there is a trade‐off between success at pre‐ and postcopulatory mating success. Recently, this trade‐off has been demonstrated with experimental manipulation. Males of the leaf‐footed cactus bug Narnia femorata use hind limbs as the primary weapon in male–male competition. However, males can drop a hind limb to avoid entrapment. When this autotomy occurs during development, they invest instead in large testes. While evolutionary outcomes of the trade‐offs between pre‐ and postcopulatory strategies have been identified, less work has been done to identify proximate mechanisms by which the trade‐off might occur, perhaps because the systems in which the trade‐offs have been investigated are not ones that have the molecular tools required for exploring mechanism. Here, we applied knowledge from a related model species for which we have developmental knowledge and molecular tools, the milkweed bug Oncopeltus fasciatus, to investigate the proximate mechanism by which autotomized N. femorata males developed larger testes. Autotomized males had evidence of a higher rate of transit amplification divisions in the spermatogonia, which would result more spermatocytes and thus in greater sperm numbers. Identification of mechanisms underlying a trade‐off can help our understanding of the direction and constraints on evolutionary trajectories and thus the evolutionary potential under multiple forms of selection.

The role of natural enemies in promoting coexistence of competing species has generated substantial debate. Modern coexistence theory provides a detailed framework to investigate this topic, but there have been remarkably few empirical applications to the impact of natural enemies. We tested experimentally the capacity for a generalist enemy to promote coexistence of competing insect species, and the extent to which any impact can be predicted by trade-offs between reproductive rate and susceptibility to natural enemies. We used experimental mesocosms to conduct a fully factorial pairwise competition experiment for six rainforest Drosophila species, with and without a generalist pupal parasitoid. We then parameterised models of competition and examined the coexistence of each pair of Drosophila species within the framework of modern coexistence theory. We found idiosyncratic impacts of parasitism on pairwise coexistence, mediated through changes in fitness differences, not niche differences. There was no evidence of an overall reproductive rate-susceptibility trade-off. Pairwise reproductive rate-susceptibility relationships were not useful shortcuts for predicting the impact of parasitism on coexistence. Our results exemplify the value of modern coexistence theory in multi-trophic contexts and the importance of contextualising the impact of generalist natural enemies to determine their impact. In the set of species investigated, competition was affected by the higher trophic level, but the overall impact on coexistence cannot be easily predicted just from knowledge of relative susceptibility. Methodologically, our Bayesian approach highlights issues with the separability of model parameters within modern coexistence theory and shows how using the full posterior parameter distribution improves inferences. This method should be widely applicable for understanding species coexistence in a range of systems.同生态位物种间的共存受到它们共同天敌的调控。这一调控的影响仍备受争议。现代共存理论为这一问题提供了量化的研究框架, 但相关的实证研究还远远落后于理论进展。 我们通过实验探究了非特异性寄生蜂如何调控其宿主之间的竞争性共存, 并尝试用宿主的繁殖力与免疫力间的关系对共存结果加以解释。 在实验室的模拟实验中, 我们将六个热带雨林果蝇物种两两组合后放置于有或者没有寄生蜂的环境下, 记录子代果蝇的数量。我们用这些实验数据拟合出宿主间的物种竞争模型, 再通过现代共存理论推导宿主间的共存关系。 我们发现非特异性寄生蜂改变了不同宿主物种间的适合度差异, 但并没有改变它们的生态位差异。非特异性寄生蜂最终的调控效果依宿主组合的不同而不同, 并没有统一的规律。宿主的繁殖力和免疫力间并不普遍存在此消彼长的关系。即使在某几对宿主间存在负相关性, 寄生蜂的调控也并不总是促进共存。 我们的研究示范了如何将现代共存理论应用于多营养级生态网络,强调了寄生蜂对宿主间共存的影响依具体情况而定: 宿主物种间的竞争受到更高营养级的调控, 而此调控对宿主间共存的影响并不能简单地通过它们的对寄生蜂的免疫能力进行预测。另外, 我们的统计分析指出了在应用现代共存理论到实际系统时将面临的参数协变性问题, 并展示了如何利用贝叶斯统计方法完善对物种共存关系的推测。我们推荐这一方法被更广泛地应用于物种间共存的研究。.

Adaptation to environmental temperature depends on both direct and correlated responses to selection for reproduction and survival at elevated temperature. Sexual selection is one of the most powerful of all evolutionary forces and we tested both fecundity and longevity for their correlated responses to sexual selection on the ability to mate (mating success) at high temperature. Replicated lines selected for 15 generations of mating at 33 °C (S lines) were compared to their respective controls (C lines) in D. buzzatii in three thermal regimes: 25 °C, 30 °C and a cyclic thermal regime for longevity from 17 to 32 °C. Previous work showed that S lines successfully responded for the trait selected and the present results show a trade-off in males between mating success at elevated temperature and longevity in all three thermal regimes tested. In addition, inter-sexual relationships of trade-offs were apparent between male longevity and female fecundity as correlated selection responses. In this sex-specific association of trade off, S females exhibited higher fecundity than C females at 30 °C only if females were exposed to a limited social environment of a single male. Overall, selection for mating at high temperature increases female fecundity at high temperature but decreases longevity in males. This sex-specific and negative impact on longevity in males could be the result of a genetic correlation between mating success at high temperature and reduced longevity in this sex.

We investigated the performance trade-offs of fleas (Siphonaptera) while adapting to a novel host using two host generalists (Xenopsylla conformis and Xenopsylla ramesis) and one host specialist (Parapulex chephrenis) maintained on their principal hosts (Meriones crassus for Xenopsylla and Acomys cahirinus for P. chephrenis). We asked whether, over generations, (i) a host generalist may become a specialist by evolving the ability to exploit a novel host and losing the ability to exploit an original host and (ii) a host specialist can become a generalist by evolving the ability to exploit a novel host without losing the ability to exploit an original host. We established an experimental line of each species on a novel host (Acomys russatus for Xenopsylla and M. crassus for P. chephrenis) and maintained this line on this host during 23 generations. We compared reproductive performance of progenitors of each line and their descendants when they exploited either original or novel host in terms of egg number and size, hatching success, offspring production, and offspring size. We found changes in performance over generations in female offspring size only. Xenopsylla conformis demonstrated a tendency to become a host specialist (increased performance on the novel host with a concomitant decreased performance on the original host), whereas P. chephrenis demonstrated a tendency to become a host generalist (increased performance on the novel host without a concomitant decreased performance on the original host). We conclude that the probability of generalist to specialist transition, and vice versa, is context-dependent and varies between species.

In many vertebrate societies dominant individuals breed at substantially higher rates than subordinates, but whether this hastens ageing remains poorly understood. While frequent reproduction may trade off against somatic maintenance, the extraordinary fecundity and longevity of some social insect queens highlight that breeders need not always suffer more rapid somatic deterioration than their nonbreeding subordinates. Here, we used extensive longitudinal assessments of telomere dynamics to investigate the impact of dominance status on within-individual age-related changes in somatic integrity in a wild social bird, the white-browed sparrow-weaver (Plocepasser mahali). Dominant birds, who monopolise reproduction, had neither shorter telomeres nor faster telomere attrition rates over the long-term (1-5 years) than their subordinates. However, over shorter (half-year) time intervals dominants with shorter telomeres showed lower rates of telomere attrition (and evidence suggestive of telomere lengthening), while the same was not true among subordinates. Dominants may therefore invest more heavily in telomere length regulation (and/or somatic maintenance more broadly); a strategy that could mitigate the long-term costs of reproductive effort, leaving their long-term telomere dynamics comparable to those of subordinates. Consistent with the expectation that reproduction entails short-term costs to somatic integrity, telomere attrition rates were most severe for all birds during the breeding seasons of wetter years (rainfall is the key driver of reproductive activity in this arid-zone species). Our findings suggest that, even in vertebrate societies in which dominants monopolise reproduction, dominants may experience long-term somatic integrity trajectories indistinguishable from those of their nonreproductive subordinates.

It is crucial to evaluate ethical issues regarding evacuation orders, especially after a nuclear disaster. After the Fukushima accident in 2011, the Japanese government ordered the affected people to evacuate. The evacuation orders have now been lifted in many areas. A risk trade-off analysis between benefits and risk associated with returning home would help in evaluating the justification for the lifting of the evacuation order in the aftermath of a nuclear disaster. Here, we performed a risk trade-off analysis among people returning home after the lifting of an evacuation order between an increase in emotional happiness (positive effect) and loss of life expectancy due to additional radiation exposure (negative effect), using a happy life expectancy (HpLE) indicator. Emotional happiness was estimated using questionnaires distributed among the affected people who lived in municipalities where evacuation orders were lifted. Loss of life expectancy was estimated under a scenario that returnees received 20 mSv in the year of return and subsequent radiation exposure. Increase in emotional happiness due to returning home was ~1–2 orders of magnitude higher among women aged 20, 40 and 65 years than the loss of life expectancy due to additional radiation exposure. This finding has implications for the justification for the lifting of evacuation orders.

Goal: This research aims to examine the trade-off behaviour between productivity, quality and maintenance performance and evaluate the efficiency of the framework integrated to a time variability in operational management. Design / Methodology / Approach: The proposed framework integrates a stochastic analysis of process and TVM to manage process variability and analyse the trade-off behaviour between quality, productivity, and maintenance efficiency. The framework generates a control chart for each workstation and analyses the operator's time to execute an assembly process for six workstations. The processes are characterised and evaluated via stochastic simulation, resulting in a trade-off analysis with a multicriteria approach. Results: A relational graphic of performance dimensions shows that productivity and maintenance performance have a high dependency on time variability management, whereas quality has a minor impact over trade-off decisions. The proposed framework has a huge significance to operational management which allow to apply complex models to time variability analysis and organisation performance. Limitations of the investigation: The trade-off analysis in this study is limited to a constant trade-off model to validate the framework. Practical implications: This framework, used in association with traditional management philosophies, is a powerful tool that permits managers to develop a trade-off analysis and make decisions on workstations. Thus, a research field that correlates time variability with performance dimensions may be validated by this framework. Originality / Value: A framework that allows the use of MCDM to analyse the trade-off behaviour on organization performance and a trade-off analysis between performance dimensions and time variability management in operational performance.

The mainstream strategy in the coordination of agri-food chains has traditionally focused more on the enhancement of chain performance by adopting lean and highly integrated strategies. These strategies are premised on the principle that governance structures are the result of tactics that economize on transaction costs in exchanges in chains. Due to existing interdependencies between chain players such strategies expose these chains to detrimentally disruptive uncertainty. This paper adopted a heuristic stress-testing approach to measure the fragility of South African egg value chain and performed a comparative fragility analysis of two coordination approaches in the egg chain. Additionally, the analysis of results indicated that the egg chain strategy with high levels of interdependencies between its chain players as significantly fragile. Precisely, the difference between the chain strategies was associated with a variety of differences at the factor and chain player levels that led up to a higher overall chain fragility of the chain with higher levels of interdependency. Inevitably, the paper propositions that there is a trade-off between chain performance and fragility. The results of the study affirmed that there is a trade-off between chain performance and fragility which needs to be balanced.

Do people prefer a job that promotes feelings of enjoyment, or of competence? The present research examined the role of individuals’ happiness in choosing the type of work to engage in when selecting between two characteristics of the work—enjoyment and perceived competence. Studies 1, 2, and 3 revealed that happier people are more likely to value (Study 1) and to choose (Studies 2 and 3) work they enjoy over work in which they expect high competence. In Study 3, a direct manipulation of happiness increased preference for enjoyment, but not for competence. Finally, Study 4 found that happy people, when compared with their unhappy counterparts, retain their jobs because they enjoy doing their work. Together, the findings suggest that happiness leads people to place more weight on enjoyment than on competence in the enjoyment-competence trade-off context.

Trade-offs between attributes are common when making product choices. Prior research suggests that consumers tend to avoid the extremes and opt for the middle options when they make a trade-off decision between two key product attributes (e.g., tastiness and healthiness of food items) in one step. In this research, we examine how consumers make such trade-off decisions in a two-step choice process in which consumers first choose between product categories competing on two key attributes and then make a final choice within the chosen category. In three studies, we show that when holding the actual choice options unchanged, consumers are more likely to make a more extreme final choice, prioritizing a single attribute rather than compromising when they follow a two-step choice process instead of a one-step process.

Overwintering is a challenging period in the life of temperate insects. A limited energy budget characteristic of this period can result in reduced investment in immune system. Here, we investigated selected physiological and immunological parameters in laboratory‐reared and field‐collected harlequin ladybirds (Harmonia axyridis). For laboratory‐reared beetles, we focused on the effects of winter temperature regime (cold, average, or warm winter) on total haemocyte concentration aiming to investigate potential effects of ongoing climate change on immune system in overwintering insects. We recorded strong reduction in haemocyte concentration during winter; however, there were only limited effects of winter temperature regime on changes in haemocyte concentration in the course of overwintering. For field‐collected beetles, we measured additional parameters, specifically: total protein concentration, antimicrobial activity against Escherichia coli, and haemocyte concentration before and after overwintering. The field experiment did not investigate effects of winter temperature, but focused on changes in inducibility of insect immune system during overwintering, that is, measured parameters were compared between naïve beetles and those challenged by Escherichia coli. Haemocyte concentration decreased during overwintering, but only in individuals challenged by Escherichia coli. Prior to overwintering, the challenged beetles had a significantly higher haemocyte concentration compared to naïve beetles, whereas no difference was observed after overwintering. A similar pattern was observed also for antimicrobial activity against Escherichia coli as challenged beetles outperformed naïve beetles before overwintering, but not after winter. In both sexes, total protein concentration increased in the course of overwintering, but females had a significantly higher total protein concentration in their hemolymph compared to males. In general, our results revealed that insect’s ability to respond to an immune challenge is significantly reduced in the course of overwintering., Prior to overwintering, the challenged insects had a significantly higher haemocyte concentration compared to naïve insects, whereas no difference was observed after overwintering. A similar pattern was observed also for antimicrobial activity against Escherichia coli as challenged insects outperformed naïve insects before overwintering, but not after winter.

Life‐history trade‐offs are important coexistence mechanisms in plant communities. In particular, a trade‐off between seed quality and seed output may explain coexistence among species with a wide variety of seed sizes in heterogeneous landscapes with varying degrees of local stresses such as shade, drought and browsing. Under spatially implicit formulations of the tolerance‐fecundity trade‐off, species diversity is only bounded by community size and environmental heterogeneity. However, these formulations leave unanswered the question of how dispersal limitation, an important aspect of real communities, impacts the ability of the tolerance‐fecundity trade‐off to support coexistence. Here we show using stochastic cellular automata that coexistence under the tolerance‐fecundity trade‐off in a spatially structured landscape is strongly modulated by the interactions between the spatial scales of species dispersal and environmental variability. Specifically, coexistence in a patchy landscape is higher under short dispersal scales relative to the scale of environmental variation. These conditions allow species to segregate spatially and thus avoid interspecific competition. In addition to dispersal limitation, coexistence under the tolerance‐fecundity trade‐off is promoted by a sharp drop in tolerance as local environmental stress increases, a high overall seed output across species, local homogeneity in environmental conditions and weak age structure in fertility. In particular, coexistence is much higher when species have full tolerance to stress levels below a threshold and zero tolerance above that threshold, with nothing in between. This steep gradient contributes to coexistence because it maximizes niche separation between similar species. Synthesis. When plants compete for space, dispersal limitation and landscape spatial structure can conspire to boost coexistence and diversity. Our results show that the tolerance‐fecundity trade‐off is a strong niche differentiation mechanism when species experience a well‐defined distinction between suitable and unsuitable environments, and supports higher diversity when dispersal scales are shorter than the scales of variation in the environment. We conclude that the trade‐off is more likely to be a relevant coexistence mechanism in the context of large‐scale environmental variation, such as topography, than small‐scale variation, such as in litter cover and canopy shading.

Research aim : This study aimed to strengthen empirical evidence that the trade-off (TOT) and pecking order (POT) theories in Indonesia are non-mutually exclusive. Design/methodology/approach : This study employed a sample of 636 manufacturing companies from 2014 to 2018. Research finding : The results revealed that companies in Indonesia used a Capital Structure consistent (CS) with the TOT and POT, or in other words, the TOT and POT theories are non-mutually exclusive. Theoretical contribution/originality : This study is different from previous research on data analysis strengthened by separating underleveraged and overleveraged companies. Practitioner/Policy implication : CS in Indonesia is following the TOT if it is underleveraged and according to POT if it is overleveraged. Research limitation/implication : This study has the limitation of only using a sample of manufacturing companies in Indonesia. Subsequent research can provide comprehensive results by increasing the sample of all companies excludes the financial sector.

In this article, we carry out a combined econometric and multiobjective analysis using data from a representative sample of Andalusian schools. In particular, four econometric models are estimated in which the students’ academic performance (scores in math and reading, and percentage of students reaching a certain threshold in both subjects, respectively) are regressed against the satisfaction of students with different aspects of the teaching-learning process. From these estimates, four objective functions are defined which have been simultaneously maximized, subject to a set of constraints obtained by analyzing dependencies between explanatory variables. This multiobjective programming model is intended to optimize the students’ academic performance as a function of the students’ satisfaction. To solve this problem we use a decomposition-based evolutionary multiobjective algorithm called Global WASF-GA with different scalarizing functions which allows generating an approximation of the Pareto optimal front. In general, the results show the importance of promoting respect and closer interaction between students and teachers, as a way to increase the average performance of the students and the proportion of high performance students.

Oogenesis in mammalian females, including humans, is arrested prior to birth. Females, therefore, are born with a limited number of primary oocytes. This is in direct contrast to males in whom spermatogenesis continues during the entire lifespan following puberty. Here, we discuss possible evolutionary advantages that this confers and contrast this with age-related decline in oocyte quality that results in diminished fertility with advancing maternal age. We believe that a better understanding of these processes would be helpful in developing strategies to preserve fertility as maternal age increases, especially in the context of the current demographic shift with more and more women seeking fertility treatment at advanced age.

The paper revisits the theory of the quantity–quality trade-off and demonstrates that the relationship between quantity and health of children is subject to occupational variation in physical energ...

Behavioural thermoregulation can ameliorate thermal stress but is costly. For species that court in a thermally stressful microhabitat, sexual selection via endurance rivalry favours individuals that are able and willing to endure harsh conditions in the courtship habitat, as retreats to a thermal refuge will reduce mating opportunities. The relative costs and benefits of refuge use versus continued courtship in the face of thermal risk, which vary across abiotic and biotic contexts, determine the optimal behavioural strategy. We examined the social and abiotic factors driving behavioural decisions related to thermoregulatory retreat in the fiddler crab Austruca mjoebergi. Male fiddler crabs perform a courtship display on the thermally stressful intertidal sediment surface. Time on the surface, and thus time available for display, was limited by high temperatures; as temperature increased, surface time decreased. Yet when presented with a stimulus female, males were more likely to perform the courtship display, displayed at a higher rate and increased time spent on the surface. These results demonstrate that behavioural decisions related to thermal retreat depend both on the abiotic conditions that influence the degree of thermal stress and on the social conditions that influence the reproductive prospects of the individual.

Using the data from two leading online lending platforms in the US and China, Lending Club and Renrendai, respectively, we compare the behaviors of risk aversion and risk-return trade-off among US and Chinese online lending investors. We use the event of the implementation of “de-guarantee” policy as a quasi-natural experiment to evaluate the impact of the policy on the behaviors of online lending investors. The results of our study show that prior to 2018, the seemingly irrational behavior of Chinese lenders – blindly pursuing high interest rates regardless of default risk – is a rational response to the fact that the loans they invest in are guaranteed, and after the implementation of the “de-guarantee” policy, Chinese online lending investors exhibit similar risk-averse behaviors as US investors. In addition, we find that lenders on the US online platform consistently exhibit risk aversion behaviors and risk-return trade-off on the interest rate, while Chinese lenders do not demonstrate this trade-off before the implementation of the “de-guarantee” policy.

While aging population and technological innovation are expected to increase healthcare demand in the future, increase in healthcare spending is not likely to be sustainable in times of fiscal constraint. This might lead to a tightening of hospital capacity and, potentially, to higher patient waiting times. This paper studies waiting times and quality in a healthcare market where semi-altruistic hospitals operate at full capacity. We show that in this context a trade-off between waiting times and quality emerges which, if hospitals dislike patients to wait, decreases the incentive for the quality of care. We also show that, when hospitals operate at full capacity, standard waiting time policies involving targets and penalties (e.g., "Targets and Terror" in England) can meet the target at the expense of a lower quality of care, with relevant implications for the empirical evaluation of waiting time policy.

We study the adaptive dynamics of the colonization rate of species living in a patchy habitat when there is a trade-off with the competitive strength for individual patches. To that end, we formulate a continuous-time competition-colonization model that also includes ownership effects as well as random disturbance affecting the mortality rate. We find that intermediate disturbance (as measured by the fluctuation intensity of the mortality rate), a strong competition-colonization trade-off, and a weak ownership effect are necessary conditions for evolutionary branching and hence for the emergence of polymorphisms (i.e., coexistence) by small evolutionary steps. Specifically, concerning ownership we find that with low-intermediate disturbance, a weak ownership advantage favours evolutionary branching while ownership disadvantage does not. This asymmetry disappears at the higher-intermediate disturbance. Moreover, at a low-intermediate disturbance, the effect of the strength of the competition-colonization trade-off on evolutionary branching is non-monotonic disappears because the possibility of branching disappears again when the trade-off is too strong. We also find that there can be multiple evolutionary attractors for polymorphic populations, each with its own basin of attraction. With small but non-zero random evolutionary steps and depending on the initial polymorphic condition just after branching, a coevolutionary trajectory may come arbitrarily close to the shared boundary of two such basins and may even jump from one side to the other, which can lead to various kinds of long-term evolutionary dynamics, including evolutionary branching-extinction cycles. (C) 2021 The Author(s). Published by Elsevier Ltd.

Habits involve regular, cue-triggered routines. In a field experiment, we tested whether incentivizing exercise routines—paying participants each time they visit the gym within a planned, daily two-hour window—leads to more persistent exercise than offering flexible incentives—paying participants each day they visit the gym, regardless of timing. Routine incentives generated fewer gym visits than flexible incentives, both during our intervention and after incentives were removed. Even among subgroups that were experimentally induced to exercise at similar rates during our intervention, recipients of routine incentives exhibited a larger decrease in exercise after the intervention than recipients of flexible incentives. This paper was accepted by Yan Chen, decision analysis.

Organisms in the wild have to allocate limited resources towards competing functions such as reproduction, growth, and self-maintenance. These competing investments create significant changes in physiological activity, and we still know little about the relationship between physiological activity and reproductive investment in natura. We investigated trade-offs between physiological activity and reproductive investment in the parthenogenetic Colorado checkered whiptail, Aspidoscelis neotesselata, across three different sites at the US Army Fort Carson Military Installation near Colorado Springs, CO, throughout the reproductive season in 2018 and 2019. We measured clutch size and reproductive activity and quantified plasma corticosterone (CORT), reactive oxygen metabolites (ROMs), and bacterial killing ability (BKA) to examine how energy-mobilizing hormones, oxidative stress, and immunity change in light of reproductive investment across different sub-populations. Circulating CORT increased with reproductive investment across all sub-populations, and increased clutch size led to a decrease in BKA in one sub-population, suggesting that habitat and nutritional availability may mediate this relationship. Oxidative stress, CORT, and innate immunity were not correlated with the exception of a trade-off between ROMs and BKA. This indicates individuals that have a better capacity to fight-off pathogens suffered increased reactive oxygen metabolites across all sub-populations, independently of habitat characteristics, which has important implications for A. neotesselata conservation.

The paper brings together two distinct strands of literature that discuss the process of convergence in the EU and the impact of public debt on growth. It makes a contribution to both literatures, ...

The trade-off between quality and quantity pervades many domains of life, including that of making product choices for ourselves and others, whether as gifts or as everyday favors. In five studies (four pre-registered), participants preferred quality over quantity when choosing for a friend versus for themselves. We demonstrate that one reason why this difference in choice for self and other arises is because of heightened self-presentation concerns: People choosing for friends (vs. self) are more concerned about conveying poor taste, thus increasing choice of quality (vs. quantity). Consistent with this process, the effect is mitigated when choosing for a nonjudgmental friend or when choosing for a person whom one does not highly value. Finally, this effect is particular to quality-quantity trade-offs; it does not occur for flavor-quantity trade-offs, indicating that the effect is driven by the quality aspect rather than by the quantity aspect or by cost-per-unit considerations.

Trade-off problems concentrate on balancing the main parameters of a project as completion time, total cost and quality of activities. In this study, the problem of project time-cost-quality trade-off is formulated and solved from a new standpoint. For this purpose, completion time and crash cost of project are illustrated as fuzzy goals, also the dependency of implementing time of each activity and its execution-quality is described by a fuzzy number. The overall quality of the project execution is defined as the minimum execution-quality of the project activities that should be maximized. Based on some real assumptions, a three-objective programming problem associated with the time-cost-quality trade-off problem is formulated; then with the aim of identifying a fair and appropriate trade-off, the research problem is reformulated as a single objective linear programming by utilizing a fuzzy decision-making methodology. Generating a final preferred solution, rather than a set of Pareto optimal solutions, and having a reasonable interpretation are two most important advantages of the proposed approach. To explain the practical performance of the proposed models and approach, a time-cost-quality trade-off problem for a project with real data is solved and analyzed.

Many animals make contingent decisions, such as when and where to feed, as trade-offs between growth and risk when these vary not only with activity and location but also 1) in cycles such as the daily light cycle and 2) with feedbacks due to competition. Theory can assume an individual decides whether and where to feed, at any point in the light cycle and under any new conditions, by predicting future conditions and maximizing an approximate measure of future fitness. We develop four such theories for stream trout and evaluate them by their ability to reproduce, in an individual-based model, seven patterns observed in real trout. The patterns concern how feeding in four circadian phases—dawn, day, dusk, and night—varies with predation risk, food availability, temperature, trout density, physical habitat, day length, and circadian cycles in food availability. We found that theory must consider the full circadian cycle: decisions at one phase must consider what happens in other phases. Three theories that do so could reproduce almost all the patterns, and their ability to let individuals adapt decisions over time produced higher average fitness than any fixed behavior cycle. Because individuals could adapt by selecting among habitat patches as well as activity, multiple behaviors produced similar fitness. Our most successful theories base selection of habitat and activity at each phase on memory of survival probabilities and growth rates experienced 1) in the three previous phases of the current day or 2) in each phase of several previous days.

Development of insecticide resistance often changes life history traits of insect pests, because metabolic detoxification of insecticides in insect bodies requires huge energetic reserves. The brown planthopper, Nilaparvata lugens (Stål), an important insect pest of rice crop in East and Southeast Asia, has developed strong resistance to imidacloprid from mid-2000s. The aim of this study was to examine the costs of life history traits and reveal changes in energy reserves with developing imidacloprid resistance. We compared the life history traits (survival time, fecundity, developmental time, and hatchability) and total lipid content between imidacloprid-resistant and imidacloprid-susceptible (control) brown planthopper strains. As compared to the control strains, adults’ survival time of the resistant females was shorter, and their fecundity was lower; the other life history traits did not differ significantly between the resistant and control strains. As the results, net reproductive rates (R0) were lower in the resistant strains than in the susceptible strains. However, the amount of stored lipids was larger in resistant females than control ones. Our findings demonstrated a physiological trade-off between the development of imidacloprid resistance and the reproductive traits of brown planthopper. The imidacloprid-resistant strains are likely to store lipids for metabolic detoxification rather than consume them for reproduction.

During egg laying, females face a trade‐off between self‐maintenance and investment into current reproduction, since providing eggs with resources is energetically demanding, in particular if females lay one egg per day. However, the costs of egg laying not only relate to energetic requirements, but also depend on the availability of specific resources that are vital for egg production and embryonic development. One of these compounds are carotenoids, pigments with immuno‐stimulatory properties, which are crucial during embryonic development. In this study, we explore how carotenoid availability alleviates this trade‐off and facilitates egg laying in a small bird species, the blue tit (Cyanistes caeruleus). Blue tits have among the largest clutch size of all European passerines and they usually lay one egg per day, although laying interruptions are frequent. We performed a lutein supplementation experiment and measured potential consequences for egg laying capacity and egg quality. We found that lutein‐supplemented females had less laying interruptions and thus completed their clutch faster than control females. No effects of treatment were found on the onset of egg laying or clutch size. Experimentally enhanced carotenoid availability did not elevate yolk carotenoid levels or egg mass, but negatively affected eggshell thickness. Our results provide hence evidence on the limiting role of carotenoids during egg laying. However, the benefits of laying faster following lutein supplementation were counterbalanced by a lower accumulation of calcium in the eggshell. Thus, even though single components may constrain egg laying, it is the combined availability of a range of different resources which ultimately determines egg quality and thus embryonic development., This study provides the first evidence of limiting role of carotenoid during egg production. Experimentally enhanced carotenoid availability facilitated egg laying in blue tit females.

Time, cost and quality are major concerns in construction project management. To achieve a balance between time-cost and time-quality, a trade-off problem among time-cost-quality (TCQ) is proposed for optimisation by the application of a genetic algorithm (GA). A GA attempts to minimise a fitness function that describes the objective to be achieved. The fitness function is specifically designed according to the nature and characteristics of the construction project. By inputting the project parameters, the fitness function should be able to provide a balance between the time, cost and quality of the project. This study applied a GA to strategically search for the best project parameters for an offshore wind farm project to achieve a more accurate prediction for construction time, cost and quality of the project in the pre-construction stage. A series of practical mathematical models are developed through a review of previous studies based on specific merits, and a real offshore wind farm project is studied to identify and verify the applicability and viability of the mathematical models. After the process of optimisation, the results show that the output data is very close to the actual case in terms of construction time, cost and quality.

Additive manufacturing (AM) is a technology that creates parts directly from 3D CAD files based on a layer-by-layer manufacturing process. Quality and productivity are the two key concerns in powder-bed AM processes, which are one of the most widely used AM in the industry. Because of the keyholes and porosity formation occurring in the object’s structure during a printing process, quality is considered a difficult factor to manage. On the other side, focusing only improving quality could result in higher building cost and inefficient printing operations. Thus, a trade-off between these two concerns is vital for maintaining competitiveness of AM. To the best of our knowledge, there is no study in the literature that has yet considered this trade-off in a systematic way and can provide optimal results for productivity based on a desired quality level. This study combined equations from previous studies in a systematic way to create an empirical model to optimize major process parameters, including laser power, scan speed, layer thickness, hatch distance, and laser spot size for a trade-off between quality and productivity in powder-bed AM processes. The combined and individual effects of all process parameters were analyzed in a numerical experiment to show their significance for the printing process. The case study also showed that the proposed empirical optimization model yielded lower building costs than those from similar studies in the literature and is effective on maximizing productivity at the desired quality level.

In this work, the author proposes a optimal process mean setting for product with quality loss and process adjustment cost. Assume that the quality characteristic is exponentially distributed with ...

In this paper, I revisit the central trade-off between insurance and incentives in the design of unemployment insurance policies. The generosity of unemployment insurance benefits differs not only across countries, but also across workers within countries. After illustrating some important dimensions of heterogeneity in a cross-country analysis, I extend the standard Baily–Chetty formula to identify the key empirical moments and elasticities required to evaluate the differentiated unemployment policy within a country. I also review some prior work and aim to provide guidance for future work trying to inform the design of unemployment policies.

In this study, the author considers the problem about economic process mean selection of product with the quality loss and process adjustment cost. Assume that the quality characteristic is normall...

This article analyzes one aspect of the trade-off between state aid and mergers faced by ailing firms when they want to avoid bankruptcy. It questions the existence of strategic aid made with the unique goal of influencing the competition authority’s beliefs regarding the competition. To analyze those aids, we create a model in which an authority is trying to deter strategic aid while being uninformed about competition. We show that when firms in difficulty know about the authority’s beliefs regarding competition, they implement strategic aid. The authority is able to deter them, but has to choose between deterring them and maximizing firms’ survival. When firms do not know the authority’s beliefs, strategic aid exists, and the authority is not able to minimize the percentage of aid. Nevertheless, the authority is efficient since simulations show that less than 1% of firms in difficulty are implementing strategic aid, thanks to this policy.

Strategic managers are consistently faced with decisions of how to allocate a company's scarce resources to meet the demands of shareholders and other powerful and legitimate stakeholders. This article analyses whether higher union density at company level pushes management to engage more in corporate social responsibility (CSR). Drawing from stakeholder theory and the resource allocation approach of CSR as well as union voice and monopoly models, this article finds that companies have to substitute non–employee‐oriented CSR with employee‐oriented CSR as union density increases but is still at low levels. At higher levels of union density, companies can complement both types of CSR. This perhaps represents a reinforcement of mutual interests between management and organized labour, which has implications for managerial prerogatives as well as union positioning in the labour and political process.\ud \ud

This article asks whether the strengthened, institutionalised role that some European agencies play in delegated decision-making endangers their actual independence. In some particular sensitive policy domains, such as pharmaceuticals security, financial markets and energy, European agencies exist which are formal agenda-setters in delegated decision-making, meaning that the European Commission can either accept or reject their proposals but is hardly allowed to change them. These procedures were established to guarantee particularly expert-based decision-making. However, the article argues that under these conditions, the Commission will be eager to interfere with the agencies’ proposal preparation to ensure that the proposal is in line with its position, thereby weakening the de facto independence of agencies. Such procedures come, therefore, with unexpected effects in practice. However, the article demonstrates that these effects vary with organisational resources on the agencies’ and the Commission’ side and the expected constraining effects of the decisions taken.