The effects of success-failure on the perception of threat in a competitive situation.
Explore the source record for details and available documents.
Achievement↗
SEARCH · PubMed Health
Results for “Competitive Behavior”
Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
The effects of training and position on judges' ratings of a gymnastic event.
Explore the source record for details and available documents.
Competitive Behavior↗
Effect of cadmium level and exposure time on the competition between zooplankton species Moina macrocopa (Cladocera) and Brachionus calyciflorus (Rotifera).
Competition among zooplankton is a natural phenomenon and often cladocerans are competitively superior to rotifers. However, anthropogenic factors including the release of industrial effluents, may influence this interaction. In this study, we evaluated the effect of cadmium (0.05 and 0.1 mg L(-1) as CdCl(2)) on competition between the cladoceran Moina macrocopa and the rotifer Brachionus calyciflorus. Since the release of industrial effluents is generally pulsed, we also exposed the test zooplankton species at different exposure periods (3, 6, 12 and 24 h) to the heavy metal. Regardless of exposure time and the presence of competing species, an increase in concentration of Cd resulted in decreased population growth of M. macrocopa and B. calyciflorus. Regardless of presence of the competing species and Cd concentration, an increase in exposure period resulted in decreased population growth rates of both the zooplankton species. In mixed cultures, in general, M. macrocopa outcompeted B. calyciflorus and completely eliminated it under conditions of high toxicant concentrations and longer exposure time.
Animals↗
Institutional collaboration and competition in community-based education.
We sought to determine whether competition for community-based training sites exists among health professions schools, and to examine faculty and senior administrators' perspectives on institutional collaboration for community-based education. Eight academic health centers (AHCs) in the USA were selected by objective criteria for their significant community involvement. Chief executive officers, vice chancellors, deans, and the individuals responsible for community-based education, research and community service responded to written surveys. The overall response rate was 79% (n = 91). Responses were subjected to quantitative and qualitative analyses. Leaders of community-based education reported that "competition for community-based training sites" is a barrier to community involvement. "Competition for community-based training sites"was positively related to 'call for increasing percentage of graduates to enter primary care careers' (0.30, p < 0.01) and negative related to "collaboration exists between the community and your school/AHC" ( - 0.28, p < 0.05). Respondents reported that a moderate level of collaboration across schools exists. While medical school respondents reported having collaborative relationships with other health professions schools and with the community, nursing respondents reported medicine's performance at a significantly lower level. Public health and nursing faculty reported that they are competing with medical schools for sites they had traditionally used for their students. Competition for sites is an unintended outcome of the increased emphasis on community-based education in health professions curricula. We recommend AHCs form joint committees across schools to effectively address community-based sites as a limited resource, and to consider a wider range of community-based organizations as training partners.
Area Health Education Centers↗
Kinetic studies on the inhibition of GABA-T by gamma-vinyl GABA and taurine.
Gamma-aminobutyric acid transaminase (GABA-T, EC 2.6.1.19) is a pyridoxal phosphate (PLP) dependent enzyme that catalyzes the degradation of gamma-aminobutyric acid. The kinetics of this reaction are studied in vitro, both in the absence, and in the presence of two inhibitors: gamma-vinyl GABA (4-aminohex-5-enoic acid), and a natural product, taurine (ethylamine-2-sulfonic acid). A kinetic model that describes the transamination process is proposed. GABA-T from Pseudomonas fluorescens is inhibited by gamma-vinyl GABA and taurine at concentrations of 51.0 and 78.5 mM. Both inhibitors show competitive inhibition behavior when GABA is the substrate and the inhibition constant (Ki) values for gamma-vinyl GABA and taurine were found to be 26 +/- 3 mM and 68 +/- 7 mM respectively. The transamination process of alpha-ketoglutarate was not affected by the presence of gamma-vinyl GABA, whereas, taurine was a noncompetitive inhibitor of GABA-T when alpha-ketoglutarate was the substrate. The inhibition dissociation constant (Kii) for this system was found to be 96 +/- 10 mM. The Michaelis-Menten constant (Km) in the absence of inhibition, was found to be 0.79 +/- 0.11 mM, and 0.47 +/- 0.10 mM for GABA and alpha-ketoglutarate respectively.
4-Aminobutyrate Transaminase↗
Off-side front foot drives in men's high performance cricket.
We investigated the techniques used by nine right-handed, international batsmen to perform front foot off-side drives in first class and international matches. All strokes were captured using two synchronised high-speed video cameras; nine were selected for kinematic analysis. These movement sequences were then manually digitised at a sampling frequency of 125 Hz using APAS motion analysis software. The results of this study indicated that the batsmen used movement patterns that enabled important aspects of stroke production, such as the front stride and the downswing of the bat, to be delayed so that additional information from ball flight could be assimilated. Front upper limb segments were constrained to work in a unitary fashion, with the peak horizontal end point speed of each segment occurring almost simultaneously just before impact. It has been suggested that these strategies serve to enhance stroke accuracy. Other aspects of their techniques included a distinctively looped bat path, a front foot placement that occurred only just before impact, and a front ankle that was positioned well inside the line of the ball at impact. Various technical parameters, such as the alignment of the trunk relative to ground and the continuous flow of the bat between the backswing and downswing, were similar to findings in previous batting research. Other characteristics of stroke production not previously addressed, including the path of the bat and the timing of the front stride, may challenge some long held beliefs evident in current coaching literature.
Biomechanical Phenomena↗
Equipment set-up among Olympic sprint and slalom kayak paddlers.
The anthropometry and equipment set-up for sprint (31 male; 11 female) and slalom (12 male; 12 female) kayak paddlers who competed at the 2000 Olympic Games in Sydney were measured in the 15 day period before competition. This paper provides normative data for equipment set-up in these sports, as well as information about differences in rigging and paddle dimensions between sprint and slalom kayak paddlers. These differences were consistent for both male and female athletes, with sprint paddlers seated higher and using longer paddles with longer, though narrower, blades (p < 0.0001). Among male sprint paddlers, only minor differences in equipment set-up were found between competitors ranked in the top 10 places compared to the rest of the field. Considering all male paddlers initially, then sprint paddlers alone, significant (p < 0.01) regression equations were developed for the prediction of foot bar distance (r2 = 0.482 and 0.589 respectively) and hand grip distance (r2 = 0.400 and 0.541 respectively). The process of fine tuning equipment set-up often requires hours of practice with subjective feedback from the athlete. The normative data presented in this paper should assist coaches with this process as their athletes evolve toward their individual optimum set-up.
Adult↗
Variations of stroking parameters associated with 200 m competitive performance improvement in top-standard front crawl swimmers.
The aim of this study was to analyse the variations of stroking parameters (speed, stroke length, stroke rate, and stroke index) associated with the 200 m front crawl competitive performance improvement. Two races completed by 17 top swimmers were analysed in the 200 m freestyle final of French or European championships, each final being separated by two years. All the swimmers' performances were bettered in the second race (mean +/- SD: 113.44 +/- 2.50 vs 111.78 +/- 2.71 s; p < 0.01) and were associated with a significant increase of stroke rate without variation of average stroke length and stroke index values (p > 0.05). Swimmers emphasized the first part of the race, with higher speed in the first three lengths, higher stroke rate in the first two lengths and lower stroke length in the first one. Stroke length and stroke rate variations were highly correlated (r = 0.98; p < 0.05). In 11 of the 17 swimmers, the improvement was concomitant with a decrease in stroke length and an increase in stroke rate. Only one swimmer's improvement was associated with a substantial increase in stroke length. These results highlighted that stroke length and stroke index cannot be considered as the only parameters linked to improvement in a 200 m crawl in adult swimmers competing at high standard. Moreover, an increase in stroke rate associated with a slight decrease in stroke length should not be considered as ineffective, especially at top standard.
Adaptation, Physiological↗
Dynamic perception in chess.
The present study examines the dynamic aspects of perceptual processes in expert chess players. This topic is approached in terms of the anticipation processes carried out by experienced players during the encoding of chess positions. The aim of the first experiment, which used a short-term comparison task, was to stress the role of anticipation, which allows expert players to focus their attention on the area of the studied position where they expect the likely standard move to occur. The second experiment used a long-term recognition task. The results showed that expert players made many false recognitions on the new positions that could be expected from the positions presented in the preliminary study phase. Taken together, the results of the two experiments highlight the anticipatory component of expert perception.
Adolescent↗
On the coexistence of perennial plants by the competition-colonization trade-off.
Explore the source record for details and available documents.
Competitive Behavior↗
High reproductive rates result in high predation risks: a mechanism promoting the coexistence of competing prey in spatially structured populations.
I tested the hypothesis that spatial structure provides a trade-off between reproduction and predation risk and thereby facilitates predator-mediated coexistence of competing prey species. I compared a cellular automata model to a mean-field model of two prey species and their common predator. In the mean-field model, the prey species with the higher reproductive rate (the superior competitor) always outcompeted the other species (the inferior competitor), both in the presence of and the absence of the predator. In the cellular automata model, both prey species, which differed only in their reproductive rates, coexisted for a long time in the presence of their common predator at intermediate levels of predation. At low predation rates, the superior competitor dominated, while high predation rates favored the inferior competitor. This discrepancy in the results of the different models was due to a trade-off that spontaneously emerged in spatially structured populations; that is, the more clustered distribution of the superior competitor made it more susceptible to predation. In addition, coexistence of competing prey species declined with increasing dispersal ranges of either prey or predator, which suggests that the trade-off that results from spatial structure becomes less important as either prey or predator disperse over a broader range.
Animals↗
Changes in vigilance with group size under scramble competition.
Explore the source record for details and available documents.
Animals↗
Landmarks in territory partitioning: a strategically stable convention?
A convention is a rule based on arbitrary cues that allows quick resolution of potentially protracted disputes. A familiar example is the Bourgeois strategy, in which the second of two animals to discover a resource yields it to the first, even though it may be stronger than its opponent. Here we develop a game-theoretic model to show that neighbors with imperfect information about one another's fighting abilities can be favored to accept a landmark as the designator of a territory boundary, even when the resulting territory is smaller than the one that would have been won through fighting. Thus, the use of landmarks or other mutually obvious solutions can serve as a convention for territory partitioning. For a distribution of fighting ability with low variance and high skew, there is a remarkably high probability that an animal will accept a smaller territory than it would have won through fighting. The analysis provides a possible explanation for the observed use of landmarks as boundary markers by territorial animals in a variety of taxa, including birds, fish, insects, and mammals. The analysis also suggests why territory boundaries are stable, once established, despite changes in characteristics of the residents or the environment.
Biological Evolution↗
A new version of the size-advantage hypothesis for sex change: incorporating sperm competition and size-fecundity skew.
Traditional sex-change theory cannot explain the existence of protogynous species in which the largest females do not change sex when provided an opportunity. We present an expected reproductive success threshold model that incorporates previously unconsidered factors (size-fecundity skew and sperm competition) that can strongly affect reproductive expectations. The model predicts a variety of circumstances when the largest females remaining in a social group should not change sex in the absence of the dominant male, yet it also predicts that these same conditions should promote sex change in smaller females. If a large female's fecundity is markedly higher than the aggregate of the other members of her social group (i.e., there exists a skew in the size-fecundity distribution that raises a large female's expected reproductive success threshold), she should defer from sex change. Sperm competition can strongly lower the expectation of paternity obtained as a sex-changed male, and this also raises the threshold. The model suggests that deferral of sex change should be more common in species in which intense sperm competition is prevalent (such as fishes living in seagrass beds). This prediction appears consistent with patterns seen in nature.
Animals↗
Reproductive uncertainty and the relative competitiveness of simultaneous hermaphroditism versus dioecy.
Hermaphroditism is typically associated with a sedentary existence, whereas dioecy is associated with mobility. This pattern is reflected within flowering plants, as dioecious species commonly possess traits that promote high dispersal. We investigated these associations with three population dynamics models (an individual-based simulation and two mathematical models, one deterministic and the other stochastic) that allowed us to examine competition for space between a hermaphroditic and dioecious species from different perspectives. The competing species are identical in every way but their sexual system. Separation of the sexes increases the variances of pollen import and seed dispersal for the dioecious species. These variances propagate through subsequent reproductive processes and ultimately reduce mean recruitment as a result of nonlinear averaging (Jensen's inequality). A dioecious species could overcome this disadvantage simply by producing more gametes than hermaphrodites; however, in line with the association with mobility, selection on dioecious species should also favor traits that reduce reproductive uncertainty, such as extensive dispersal.
Biological Evolution↗
Ecological dynamics of mutualist/antagonist communities.
One approach to understanding how mutualisms function in community settings is to model well-studied pairwise interactions in the presence of the few species with which they interact most strongly. In nature, such species are often specialized antagonists of one or both mutualists. Hence, these models can also shed light on the problem of when and how mutualisms are able to persist in the face of exploitation. We used spatial stochastic simulations to model the ecological dynamics of obligate, species-specific mutualisms between plants and pollinating seed parasite insects (e.g., yuccas and yucca moths) in the presence of one of two obligate antagonist species: flower-feeding insects (florivores) or insects that parasitize seeds but fail to pollinate (exploiters). Our results suggest that mutualisms can persist surprisingly well in the presence of highly specialized antagonists but that they exhibit distinctly different temporal and spatial dynamics when antagonists are present. In our models, antagonists tend to induce oscillations in the mutualist populations. As the number of per capita visits by antagonists increase, the system's oscillatory dynamics become more extreme, finally leading to the extinction of one or more of the three species. When the antagonists exhibit high per capita visitation frequencies and long dispersal distances, significant spatial patchiness emerges within these tripartite interactions. We found surprisingly little difference between the ecological effects of florivores and exploiters, although in general florivores tended to drive themselves (and sometimes the mutualists) to extinction at parameter values at which the exploiters were able to persist. These theoretical results suggest several testable hypotheses regarding the ecological and evolutionary persistence of mutualisms. More broadly, they point to the critical importance of studying the dynamics of pairwise interactions in community contexts.
Animals↗
Competition and coexistence: exploring mechanisms that restrict and maintain diversity within mutualist guilds.
Mutualistic interactions are diverse and widespread and often involve multispecies guilds of mutualists competing for access to one or more partner species. Despite the ubiquity of these interactions, we know little about the dynamics of competition and coexistence within these guilds or how interactions between mutualists and their shared resource (the partner species) may influence these dynamics. In this article, we review the evidence for interspecific competition for partners within mutualist guilds in both plant-pollinator and ant-myrmecophyte systems. We then review evidence for the operation of different coexistence mechanisms within these guilds and discuss how the dynamics of competition and coexistence may be uniquely shaped by multispecies mutualist interactions. In particular, we note that adaptive and plastic responses by mutualists to variation in partner quality are likely to play an important role in determining these dynamics. We summarize by considering the ecological conditions that are likely to restrict or promote species coexistence within mutualist guilds. We suggest that these guilds may provide powerful model systems for exploring multiple mechanisms of species coexistence, and we discuss how these mechanisms may be modified by evolutionary adaptation.
Adaptation, Biological↗
Determinism in a transient assemblage: the roles of dispersal and local competition.
Both dispersal and local competitive ability may determine the outcome of competition among species that cannot coexist locally. I develop a spatially implicit model of two-species competition at a small spatial scale. The model predicts the relative fitness of two competitors based on local reproductive rates and regional dispersal rates in the context of the number, size, and extinction probability of habitat patches in the landscape. I test the predictions of this model experimentally using two genotypes of the bacteriophagous soil nematode Caenorhabditis elegans in patchy microcosms. One genotype has higher fecundity while the other is a better disperser. With such a fecundity-dispersal trade-off between competitors, the model predicts that relative fitness will be affected most by local population size when patches do not go extinct and by the number of patches when there is a high probability of patch extinction. The microcosm experiments support the model predictions. Both approaches suggest that competitive dominance in a patchily distributed transient assemblage will depend upon the architecture and predictability of the environment. These mechanisms, operating at a small scale with high spatial admixture, may be embedded in a larger metacommunity process.
Animals↗