Competition Choice Research Articles

Divergence of sexual size dimorphism between wild and hatchery chum salmon under intensive Japanese hatchery programs

Artificial propagation weakens sexual selection by reducing male-male competition and female choice, which favor larger males in natural reproduction. If homing ability and sexual selection were strong, wild-origin salmon would exhibit more pronounced male-biased sexual size dimorphism (SSD) than their hatchery-origin counterparts. We conducted field sampling of chum salmon (Oncorhynchus keta) in two Japanese rivers, where hatchery fish were marked using otolith thermal marking. The length at maturity of hatchery salmon differed by only 1–2 cm between males and females, whereas the length at maturity of wild-dominated salmon was 5–6 cm larger in males than in females. The mean age at maturity of wild-dominated fish was 0.2–0.3 years higher than that of hatchery fish, but no significant sex differences were observed in either origin. Additionally, macro-level comparisons of SSD, calculated as log<sub>10</sub>(male length/female length), among 21 populations showed that wild-dominated populations had significantly higher SSD than hatchery-dominated populations. Overall, hatchery salmon exhibited weaker SSD, consistent with reduced sexual selection in the hatchery.

Male secreted short glycoproteins link sperm competition to the reproductive isolation of species.

Sperm competition is found across multicellular organisms1,2,3,4 using both external and internal fertilization.5,6 Sperm competition and post-copulatory cryptic female choice can promote incompatibility between species due to the antagonistic coevolution of the sexes within a species.7,8,9,10,11 This between-species incompatibility is accelerated and markedly asymmetrical when sexual mode differs, producing the "weak inbreeder, strong outcrosser" (WISO) pattern.12 Here, we show that male secreted short (MSS) sperm glycoproteins of nematodes constitute a gametic effector of WISO. In obligately outcrossing Caenorhabditis, MSS is dispensable for baseline fertility but required for intraspecific sperm competitiveness.13 MSS is lost in self-fertile lineages, likely as a response to selection for a hermaphrodite-biased sex ratio.14 Selfing hermaphrodites that mate with males of closely related outcrossing species are rapidly sterilized due to ovarian sperm invasion.11 The simplification of the male proteome in selfing species suggests that many factors could contribute to invasivity.13,15,16 However, restoration of just MSS to the self-fertile C.briggsae is sufficient to induce mild invasivity. Further, MSS+ sperm appear to derive their competitive advantage from this behavior, directly linking interspecies incompatibility with intraspecific competition. MSS-related proteins (MSRPs) remaining in the C.briggsae genome are similar in structure, expression, and localization to MSS but are not necessary for normal sperm competitiveness. Further, overexpression of the MSRP most similar to MSS, Cbr-MSRP-3, is insufficient to enhance competitiveness. We conclude that outcrossing species retain sperm competition factors that contribute to their reproductive isolation from selfing relatives that lost them.

Does Mixed-Ownership Reform Affect SOEs' Competitive Strategies?

State-owned enterprises (SOEs) are the leading force of the socialist economy, and their competitive strategy choice is the key to the high-quality development of micro-enterprises and even the national economy. This paper constructs the variables of mixed-ownership reform from shareholder power and board power and explores the impact of mixed-ownership reform on the competitive strategy of SOEs. We find that the higher the degree of SOEs' mixed-ownership reform, the greater the shareholder power and the board power held by non-state-owned shareholders, and the more inclined they are to carry out a differentiation strategy. The mechanism test shows that mixed-ownership reform eases the financing constraints and improves the risk-taking level, facilitating SOEs to choose a differentiation strategy. Further research states that the positive effect of mixed-ownership reform on differentiation strategy is more evident in SOEs with a better external institutional environment and higher internal control quality. This study enriches the relevant literature in mixed-ownership reform and strategic management, provides empirical evidence for perfecting the governance practice at the strategic level, and has certain reference value for further promoting the sustainable development of SOEs.

Anticompetitive Consequences of Exclusivity Clauses Contained in Shopping Centres’ Lease Agreements

This article discusses the impact of commercial lease agreements concluded in shopping centres that contain exclusivity clauses on competition. It assesses whether these clauses restrict equitable retailer participation in shopping centres, thereby denying consumers competitive prices and product choices. It also demonstrates that the South African Competition Commission has classified lease agreements' exclusivity clauses as problematic and persuaded the major grocery retailers to phase them out. While this is a positive step, this article argues that there should be some regulatory framework that can ensure that none of these retailers continue to restrict competition in shopping centres by enforcing exclusivity clauses. The Commission should play a prominent role in ensuring that the terms of the consent orders signed by some of these retailers are respected to ensure that competition is promoted in shopping centres in South Africa.

Evidence for Significant Skew and Low Heritability of Competitive Male Mating Success in the Yellow Fever Mosquito Aedes aegypti.

Aedes aegpyti mosquitoes are vectors of several viruses of major public health importance, and many new control strategies target mating behaviour. Mating in this species occurs in swarms characterised by male scramble competition and female choice. These mating swarms have a male-biased operational sex ratio, which is expected to generate intense competition among males for mating opportunities. However, it is not known what proportion of swarming males successfully mate with females, how many females each male is able to mate with, and to what extent any variation in the male mating success phenotype can be explained by genetic variation. Here, we describe a novel assay to quantify individual male mating success in the presence of operational sex ratios characteristic of Ae. aegypti. Our results demonstrate that male mating success is skewed. Most males do not mate despite multiple opportunities, and very few males mate with multiple females. We compared measures of male mating success between fathers and sons and between full siblings to estimate the heritability of the trait in the narrow and broad sense, respectively. We found significant broad sense heritability estimates but little evidence for additive genetic effects, suggesting a role for dominance or epistatic effects and/or larval rearing environment in male mating success. These findings enhance our understanding of sexual selection in this species and have important implications for mass-release programmes that rely on the release of competitive males.

Ticketmaster's Monopoly Undermines Fair Competition in Live Entertainment Ticketing

This study investigates the monopolistic control exerted by Ticketmaster, a subsidiary of Live Nation Entertainment, within the U.S. live entertainment ticketing industry, where it holds approximately 70-80% of the primary ticketing market and 50-60% of the secondary market as of 2022. Ticketmaster’s 2010 merger with Live Nation significantly bolstered its dominance, creating a vertically integrated entity that controls artist promotion, venue management, and ticket sales, thereby limiting market competition and consumer choice. Through exclusive contracts with major venues, bundled services, and dynamic pricing practices, Ticketmaster effectively stifles alternative ticketing providers and limits consumers’ ability to choose, often resulting in inflated prices and restricted access to popular events. Utilizing a multi-faceted approach that includes market share analysis, antitrust case reviews, consumer testimony, and comparative analyses with countries such as the UK, this paper underscores the challenges posed by Ticketmaster’s market concentration. Quantitative analysis, including the Herfindahl-Hirschman Index (HHI), shows post-merger concentration levels that far exceed thresholds for competitive markets, emphasizing the lack of feasible alternatives for consumers. The Taylor Swift "Eras Tour" ticketing controversy is a case in point, illustrating the consumer impact of Ticketmaster's monopoly through reported price inflation, limited availability, and repeated service failures. The paper concludes by proposing regulatory reforms to break up the Ticketmaster-Live Nation merger, cap dynamic pricing practices, and mandate transparent fee disclosures, aiming to curb anti-competitive practices and enhance consumer protections within the ticketing industry, fostering a fairer and more accessible live entertainment ecosystem.

Pre-Copulatory Sexual Selection Predicts Sexual Size Dimorphism: A Meta-Analysis of Comparative Studies.

Size differences between males and females are common across the tree of life (termed sexual size dimorphism; SSD), and have fundamental implications for ecology, life history and behaviour of both sexes. Conventionally, SSD is thought to evolve in response to sex-specific sexual selection but more recent work suggests that ecological processes can also promote sex-differences in size. Here, we provide a global test for the role of sexual selection in the evolution of sexual size dimorphism using data from 77 comparative studies spanning the major classes of the animal kingdom. We show that intense sexual selection typically correlates with male-biased SSD across species. Importantly, pre-copulatory but not post-copulatory sexual selection predicts SSD, suggesting a pervasive role of premating male-male competition and female choice to drive sex differences in body size. Collectively, our findings suggest that pre-copulatory sexual selection plays a major role in the evolution of male-biased SSD.

Natural variation in sexual traits and gene expression between selfing and outcrossing Arabidopsis lyrata suggests sexual selection at work.

Flowering plants show significant diversity in sexual strategies, profoundly impacting the evolution of sexual traits and associated genes. Sexual selection is one of the primary evolutionary forces driving sexual trait variation, particularly evident during pollen-pistil interactions, where pollen grains compete for fertilization and females select mating partners. Multiple mating may intensify competition among pollen donors for siring, while in contrast, self-fertilization reduces sire-sire competition, relaxing the sexual selection pressure. Traits involved in male-male competition and female choice are well described, and molecular mechanisms underlying pollen development and pollen-pistil interactions have been extensively studied in the model species Arabidopsis thaliana. However, whether these molecular mechanisms are involved in sexual selection in nature remains unclear. To address this gap, we measured intrinsic pollen performance and its interaction with female choice, and investigated the associated gene expression patterns in a selfing and an outcrossing population of Arabidopsis lyrata. We found that pollen germination and pollen tube growth were significantly higher in outcrossers than selfers, and this difference was accompanied by changes in expression of genes involved in vesicle transport and cytoskeleton. Outcrosser mother plants showed a negative impact on pollen tube growth compared to selfer mother plants, together with a difference of expression for genes involved in auxin and stress response, suggesting a potential mechanism for female choice through molecular crosstalk at the post-pollination stage. Our study provides insight on the impact of sexual selection on the evolution of sexual gene expression in plants.

Metal‐loaded slot antenna with flat gain and one‐sided radiation

AbstractA metal‐loaded double‐layer unidirectional radiation slot antenna with flat gain is proposed for millimeter‐wave (mm‐wave) operations. Our presented antenna is constituted of a slot antenna with metal vias, an inner floating metal, a metal line, and ground patch. With the help of inner metal excited by the coupling of the slot antenna, an additional resonance point around 26 GHz could be obtained and the antenna gain is enhanced. To verify the design, the antenna has been fabricated with the prepreg technology. The whole fabricated size is only 0.62 × 0.62λ0² with a thickness of 0.057λ0 (λ0 is the free‐space wavelength at 26 GHz). The measured impedance bandwidth is from 25.1 to 26.55 GHz. Moreover, the proposed antenna obtains a wide flat gain (5.78 ± 0.48 dBi) within the bandwidth and stable one‐sided radiation patterns. The above characteristics show that the proposed antenna is a competitive choice for mm‐wave systems.

An Overview of the Extent of the Powers of South African Competition Authorities in the Regulation of Price Discrimination under the Competition Act 89 of 1998 in the Context of Digital Transformation

The purpose of the Competition Act 89 of 1998 as amended (the Competition Act) is, among others, to promote the efficiency, adaptability and development of the economy as well as to provide consumers with competitive prices and product choices. In line with this purpose, the Competition Act provides that a dominant firm is prohibited from engaging in price discrimination if such conduct will likely substantially prevent or lessen competition, which would be to the detriment of consumers. Notably the Competition Act has established various bodies to regulate competition and act against any conduct prohibited by this Act in South Africa. These bodies include the Competition Commission, the Competition Tribunal, and the Competition Appeal Court. Notwithstanding the prohibition of price discrimination, the Competition Act does not expressly provide adequate enforcement tools for competition authorities to combat uncompetitive practices in the digital era. Moreover, the Competition Act does not expressly grant these statutory bodies clear roles and mandates on providing consumers with adequate and suitable redress when they have been victims of algorithmic price discrimination. With recent technological developments, electronic commerce (e-commerce), and digital transformation, consumers have become vulnerable to various challenges such as excessive pricing, data breaches and algorithmic pricing. The online and digital markets are characterised by complex transactions, innovative technologies and business practices which expose all consumers, including vulnerable consumers, to different risks. As such, the role of the competition authorities needs to be recalibrated to enhance consumer protection on the pricing of goods and services. To this end this paper seeks to investigate the role and ambit of the powers of these competition authorities in the regulation of price discrimination in the context of digital transformation and the digital economy. This is done to assess whether the competition authorities have the necessary tools of enforcement to ensure that markets are competitive and to combat uncompetitive conduct in the digital economy and online markets.

Production of activated carbon from spent coffee grounds (SCG) for removal of hexavalent chromium from synthetic wastewater solutions

In this research, spent coffee grounds (SCG) are converted into a highly valuable porous adsorbent which removes chromium (VI) from wastewater with high efficiency. A set of nine Spent Coffee Ground Activated Carbon (SCG-AC) adsorbent samples were synthesized, by varying key parameters including pyrolysis temperature (400, 600 °C), pyrolysis duration (1 and 2 h), and the impregnation ratio of the activating agent, KOH (ranging from 0:1 to 2:1). Characterizations of these adsorbent samples were conducted by advanced analytical tools including SEM, EDX, XRD, FTIR, TGA, and BET. Furthermore, we carried out adsorption studies, exploring the effects of temperature and dosage variations. Additionally, point zero charge experiments and desorption studies were carried out to further understand the adsorption process. The outcomes of our investigation demonstrate the successful synthesis of these spent coffee ground-derived adsorbents, with a yield of up to 34%. Notably, these adsorbents exhibited high efficiency in extracting chromium (VI) from water, with removal efficiencies ranging from 75% to 100%. The adsorption isotherms revealed the Langmuir model to be the most fitting descriptor of the adsorption behavior. Moreover, a thermodynamics study revealed the process to be endothermic in nature which furthers our understanding of the underlying mechanisms. Importantly, our cost assessment shows the economic advantage of the synthesized adsorbent over commercial counterparts such as zeolite, making it a competitive choice for real-world applications. In summation, the study not only introduces an innovative and sustainable utilization of spent coffee grounds but also delivers an in-depth exploration of the synthesized adsorbent's ability in chromium (VI) removal. Our holistic approach, encompassing thorough experimentation, characterization, and economic evaluation, solidifies the significance of this research in tackling environmental concerns and propelling advancements in wastewater treatment methodologies.

Markov game for CV joint adaptive routing in stochastic traffic networks: A scalable learning approach

This study proposes a learning-based approach to tackle the challenge of joint adaptive routing in stochastic traffic networks with Connected Vehicles (CVs). We introduce a Markov Routing Game (MRG) to model the adaptive routing behavior of all vehicles in such networks, thereby incorporating both competitive route choices and real-time decision-making. We establish the existence of the Nash policy (i.e., optimal joint adaptive routing policy) within the MRG that enables vehicles to adapt optimally to real-time traffic conditions online through efficient communication. To enhance scalability, we innovate with a homogeneity-based mean-field approximation method and, based on that, further develop the Homogeneity-based Mean-Field Deep Reinforcement Learning (HMF-DRL) algorithm to learn the Nash policy within the MRG. Through numerical experiments on the Nguyen–Dupuis network, we demonstrate our algorithm’s ability to efficiently converge and learn the joint adaptive routing policy that significantly enhances traffic network efficiency. Furthermore, our study provides insights into the effects of travel demand, penetration of CVs, and levels of uncertainty on the performance of the joint adaptive routing policy. This paper presents a significant step towards improving network efficiency and reducing the travel time for a majority of vehicles amid uncertain traffic conditions.

Energy sales activities development in electric power market

The energy sales activities development processes in the electric power industry have been studied. The factors determining the infrastructural nature of activity in the modern market, aimed at supporting opportunities for implementing competitive transactions of electric power purchase and sale, have been formulated. The process of planning to implement in 2005–2008 a “resale” scheme for organizing energy sales activities in the course of developing a new market model has been assessed. The choice of such a scheme is not simple and not the best of possible solutions. The problems arising for economic entities in the modern Russian electric power market under the conditions of the “resale” scheme for organizing energy sales activities have been characterized. Mechanisms and procedures of the market do not provide its subjects with acceptable competition conditions. This is largely due to the fact that energy sales companies, seeking to preserve and expand the monopoly sale of electricity, suppress the possibility of competitive choice of its suppliers and consumers, creating conditions of entrepreneurship low efficiency in the market. The article proposes approaches to improving energy sales activities based on the implementing the “agency” scheme within the framework of the electric power market digital model with the solution of tasks to provide its subjects with opportunities for competitive choice, ensuring fair competition conditions for detecting and implementing opportunities to obtain entrepreneurial benefits.

Design and development of a 4He sub-Kelvin sorption cooler

The sub-Kelvin sorption cooler (SKSC) has emerged as a reliable and vibration-free solution for space cryogenics, establishing itself as a highly competitive choice. This paper focuses on the development of a 4He SKSC prototype designed for precooling an adiabatic demagnetization refrigerator (ADR). Based on the sorption refrigeration mechanism, the relationship between the amount of working medium and cooling performance is analyzed. Subsequently, each component of the SKSC is designed and constructed, resulting in the successful creation of a 4He SKSC prototype. Experimental testing demonstrates its capability to achieve a minimum temperature of 773 mK and provide a cooling capacity of 100 μW at 803 mK.

Ag-MWCNT Composites for Improving the Electrical and Thermal Properties of Electronic Paste.

With the development of microelectronics products with high density and high power, it is urgent to improve the electrical and thermal conductivity of electronic paste to achieve the new requirements of packaging materials. In this work, a new synthesis method of Ag-MWCNTs was designed: Firstly, carboxylated MWCNTs and stannous chloride were used as raw materials to prepare high-loading-rate Sn-MWCNT composite material to ensure the high loading rate of metal on the MWCNT surface. Then, Ag-MWCNT composite material was prepared by the chemical displacement method to solve the problem of the low loading rate of silver nanoparticles on the MWCNT surface. On the basis of this innovation, we analyzed and compared the electrical, thermal, and mechanical properties of Ag-MWCNT composite electronic paste. Compared with the electronic paste without adding Ag-MWCNTs, the resistivity was reduced by 77%, the thermal conductivity was increased by 66%, and the shear strength was increased by 15%. Therefore, the addition of Ag-MWCNTs effectively improves the electrical, thermal, and mechanical properties of the paste, making it a promising and competitive choice for new packaging materials in the future.

Trends and Paradoxes of Competitive Evolution in the Predation Mechanism

We give a series of numerical examples of competitive evolution in the predation system, showing in some cases how the choice is made to increase the efficiency of the predation mechanism (or other significant parameters) to the detriment of populations (both of prey and predators). We then develop the mathematical theory that enables us to understand the causality involved, and we identify a trend towards the emergence of the functional predation mechanism as such (and not of populations of the species involved). The realization of this trend only takes place when the conditions for it are offered by the hazards proposed to successive competitive choices. The logical structure of this trend is similar to that of the “tendency of rate of profit to fall” in certain economic models.

Paternity bias and cryptic female choice in chickens

Sperm competition and cryptic female choice (CFC) are two significant mechanisms of postcopulatory sexual selection that greatly impact fertilization success in various species. Despite extensive research has conducted on sperm competition and the evolution of sperm traits in internal fertilizers, our understanding of the female preferences in selecting sperm is still limited. Here, we aimed to investigate the characteristics of CFC in chickens by utilizing artificial insemination with mixed semen to control for variations in male fertilization success caused by female perception of male quality and mating order. Our results revealed that the offspring from multiple-mated females exhibited mixed paternity. Although the males had an equal number of viable sperm, one male consistently exhibited a 15% higher success rate on average, regardless of whether the insemination was performed with fresh or diluted semen. This result suggested that this male demonstrates superior performance in sperm competition, and exhibited a potential advantage in fertilization success. While the dominant male generally made a greater genetic contribution to most offspring, the degree of this advantage varied greatly, ranging from 11.11% to 75.00%. Furthermore, our study provided evidence of female preferences influenced the precedence of sperm from certain males over others. Interestingly, this bias is not consistently observed among all individuals, as offspring derived from some females were predominantly sired by an overall disadvantaged male while others were predominantly by a different disadvantaged male. Overall, these results underscored the complex processes involved in sperm selection and emphasized the importance of females in sexual selection theory.

Digital transformation, competitive strategy choices and firm value: evidence from China

PurposeThis research aims to examine the effects of corporate digital transformation on firm value, with a particular focus on the mediating roles played by cost leadership and differentiation strategies.Design/methodology/approachThis study employs word frequency analysis to create corporate digital transformation indicators and determine how corporate digital transformation impacts firm value. The data used in the analysis comes from 2,056 listed manufacturing enterprises in China between 2010 and 2019.FindingsThis study demonstrates that digital transformation has a favorable impact on firm value, and that cost leadership strategy and differentiation strategy significantly mediate the relationship between both of them.Research limitations/implicationsThis study utilized word frequency analysis to assess the state of corporate digital transformation. It lacked a more thorough description of internal production processes, operational efficiency, and the pace of digital transformation.Practical implicationsThe results of this study can not only promote the digital transformation and firm value, but also provide a theoretical basis for enterprises to choose a reasonable competitive strategy in the digital transformation.Originality/valueThis study contributes significantly to the field of firm value research by including digital transformation as a fundamental component. Furthermore, it investigates how cost leadership strategy and differentiation strategy play mediating roles, providing a new perspective and explanatory mechanism for understanding the influence of digital transformation on firm value.

Nigella sativa Embedded Co-axial Electrospun PVA–Collagen Composite Nanofibrous Membrane for Biomedical Applications

Mitigating health issues utilizing medicinal plants is an ancient practice that has surged in recent times due to the advent of sophisticated technology. Plant extracts incorporated in electrospun nanofibers having biocompatibility and germicidal activity are, therefore, become a competitive choice for biomedical applications. In this study, a novel co-axial electrospun nanofibrous mat with enhanced antimicrobial performance was successfully developed using poly (vinyl alcohol) in the core and collagen– Nigella sativa in the sheath. The structural analysis of the developed nanofibrous mat through a scanning electron microscope revealed the formation of nanofibers with diameters varying from 205 to 250 nm randomly oriented in the membrane. The FT-IR spectroscopy confirmed the existence of poly(vinyl alcohol), collagen, and nigella extract in the nanofibrous mat from their respective characteristic peaks. The bactericidal assay against Gram-positive Staphylococcus aureus bacteria through the agar diffusion method demonstrated an improved antibacterial performance with a higher zone of inhibition (17 and 37 mm) of the coaxial electrospun nanofibers with the increased amount of nigella extract. The moisture management profile indicated an adequate interaction between nanofibers and moisture/liquid, transferring the fluids through the membrane satisfactorily. The formation of such electrospun nanofibers will pave the way for selecting electrospinning techniques for appropriate designing and fabricating nanofibrous materials with enhanced functional properties for biomedical applications.

Strategic behaviour and decision making in competitive hospital markets: an experimental investigation

We investigate quality provision and the occurrence of strategic behaviour in competitive hospital markets where providers are assumed to be semi-altruistic towards patients. For this, we employ a laboratory experiment with a hospital market framing. Subjects decide on the quality levels for one of three competing hospitals respectively. We vary the organizational aspect of whether quality decisions within hospitals are made by individuals or teams. Realized monetary patient benefits go to real patients outside the lab. In both settings, we find that degrees of cooperation quickly converge towards negative values, implying absence of collusion and patient centred or competitive quality choices. Moreover, hospitals treat quality as a strategic complement and adjust their quality choice in the same direction as their competitors. The response magnitude for team markets is weaker; this is driven by non-cooperative or altruistic teams, which tend to set levels of quality that are strategically independent.