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PubMed2001

Implementing managed competition in Israel.

As of January 1, 1995, Israel's National Health Insurance (NHI) Law laid the foundations for regulating competition among the country's four private, not-for-profit sick funds. Prior to NHI the sick funds (SFs) had competed without governmental control. Extensive research on NHI implementation and the behavior of the sick funds (SFs) after passage of NHI reveals a paradoxical development: The NHI bill drew on the rhetoric of managed competition and did indeed establish a legal and structural framework for regulating competition among the SFs. Nevertheless, in practice, SF autonomy was constrained and competition over provision of statutory care was limited. Rather than fostering competition, the main thrust of the NHI reforms was to enhance central government's control over SF expenses in order to constrain government expenditures. The NHI reforms did encourage the SFs to cut costs and make visible service improvements. However, the reforms did not lead the SFs to reorganize, expand the scope of their services, or improve clinical quality, as the reformers had hoped. Nor did the reforms help eliminate the SF's operating deficits or insure financial stability for the whole health system. Furthermore, the reforms had unanticipated and undesired outcomes, including aggressive and illegal marketing by SFs and collaboration among SFs to restrict the extent of care provided under compulsory insurance. The Israeli case suggests that the theory of managed competition contains unrealistic assumptions about the types of competitive behavior that result from exposure to managed competition and the capacity of government and health providers to monitor quality. In addition to stemming from universal limitations to the managed competition model, the implementation pattern in Israel reflects local, historical forces and the interplay of Israel's powerful health system actors.

Facility Regulation and Control↗
PubMed2000

Perceived competition in private dental practice in Finland.

A questionnaire study was conducted among 350 private dentists in Finland to investigate their perception of competition and how this associated with practice characteristics. The questionnaire comprised 46 questions dealing with perceptions of competition, marketing, and collegiality, respondents' personal and practice characteristics, including age, sex, area of main practice location, weekly hours in private practice, functioning in solo or in joint practice, cooperation with other dentists, and whether practicing in more than one location. The majority of these private dental practitioners perceived much competition between themselves. Almost all (96%) of those feeling much competition today expected it to be more intense after 5 years, compared to 60% of those not perceiving much competition today (P < 0.001). Private practitioners perceiving much competition also felt it from public health centers significantly (P < 0.001) more often (46%) than others (24%). Logistic regression models revealed that those with a practice in more than one location were over 7 times more likely not to perceive competition. Those practicing outside metropolitan Helsinki area had 3.6 times the odds of not perceiving competition, and for women overall the odds ratio was 2.5. Increasing competition in private practice is a widely felt concern, and it may diminish the willingness of new graduates to attempt penetration of the market and establish their clinics.

Adult↗
PubMed2000

Temporal patterning of competitive emotions: a critical review.

An interactional model of stress that integrates current research on competitive affects and emphasizes the temporal dimensions of the stress process is forwarded. The literature reveals that the study of athletes' affective responses to competition has been narrowly focused on pre-competitive anxiety. Equivocal findings on temporal patterning of competitive anxiety suggest that a fundamental change in the empirical approach is needed because the current conceptualization of anxiety and other complex emotions is imprecise. The analysis of secondary emotions as patterns of discrete basic emotions, as suggested by differential emotions theorists, is proposed for consideration in future research. In this view, competitive anxiety is considered as a set of patterns of emotions rather than a unitary affect. The adoption of this approach could result in better operationalization of competitive anxiety as well as other secondary performance-related emotions. We propose that research on competitive affects should follow two parallel lines. The first should focus on the description of complex emotional states that reflect the idiosyncratic emotional experience and vocabulary of the athlete. The second should examine the sets of basic emotions experienced throughout competition, and focus on individual differences and factors determining those differences. The integration of the two approaches could lead to a better understanding of whether, how and why individuals differ in the interpretation of specific secondary emotions and their effect on performance. Moreover, it would permit the analysis of intra-individual variations in labelling secondary emotions with respect to different competitive contexts and temporal aspects.

Anxiety↗
PubMed2000

Dwarfs and Giants: Cannibalism and Competition in Size-Structured Populations.

Cannibals and their victims often share common resources and thus potentially compete. Smaller individuals are often competitively superior to larger ones because of size-dependent scaling of foraging and metabolic rates, while larger ones may use cannibalism to counter this competition. We study the interplay between cannibalism and competition using a size-structured population model in which all individuals consume a shared resource but in which larger ones may cannibalize smaller conspecifics. In this model, intercohort competition causes single-cohort cycles when cannibalism is absent. Moderate levels of cannibalism reduce intercohort competition, enabling coexistence of many cohorts. More voracious cannibalism, in combination with competition, produces large-amplitude cycles and a bimodal population size distribution with many small and few giant individuals. These coexisting ``dwarfs'' and ``giants'' have very different life histories, resulting from a reversal in importance of cannibalism and competition. The population structure at time of birth determines whether individuals suffer severe cannibalism, with the few survivors reaching giant sizes, or whether they suffer intense intracohort competition, with all individuals remaining small. These model results agree remarkably well with empirical data on perch population dynamics. We argue that the induction of cannibalistic giants in piscivorous fish is a population-dynamic emergent phenomenon that requires a combination of size-dependent cannibalism and competition.

Perca fluviatilis↗
PubMed2000

The Interaction between Competition and Predation: A Meta-analysis of Field Experiments.

Ecologists working with a range of organisms and environments have carried out manipulative field experiments that enable us to ask questions about the interaction between competition and predation (including herbivory) and about the relative strength of competition and predation in the field. Evaluated together, such a collection of studies can offer insight into the importance and function of these factors in nature. Using a new factorial meta-analysis technique, we combined the results of 20 articles reporting on 39 published field experiments to ask whether the presence of predators affects the intensity of competitive effects and to compare the average effects of competition and predation. Across all studies, the effects of competition in the presence of predators were less than in the absence of predators, and the interaction between competition and predation for most response variables was statistically significant. Removal of competitors had much more positive effects on organisms' growth and mass than did exclusion of predators. Predator exclusion had much more beneficial effects on organisms' survival than did competition. The mean effects of competition and predation on density did not differ from one another. The results differed among trophic levels. Further understanding would benefit greatly from more field experiments that manipulate both competition and predation, that focus on a wider range of organisms and environments, that focus on population-level parameters such as density, and that report results more completely, including data such as sample sizes and variances.

competition↗
PubMed1997

Competition, ownership, and access to hospital services. Evidence from psychiatric hospitals.

OBJECTIVES: This article examines the impact of increasing competition among hospitals on access to inpatient services and preexisting differences in access between nonprofit and for-profit facilities. It tests theoretical propositions that suggest that nonprofit and for-profit hospitals will respond in different ways and to differing degrees to changing competitive pressures. METHODS: Drawing data from a 1987-88 national survey of psychiatric hospitals, the authors measured access in terms of the availability of different types of services and the provision of uncompensated care. The impact of hospital ownership, competition as well as the interaction of ownership and competition was assessed through a set of regression models, controlling for other characteristics of the hospital markets and local service system. RESULTS: Nonprofit psychiatric hospitals provide greater access than their for-profit counterparts under conditions of limited competition. Increased competition reduces the ownership-related differences in uncompensated care, but increases the differences for marginally profitable services. The market share of for-profit hospitals had an independent negative effect on access, holding constant the intensity of competition. CONCLUSIONS: The interaction of ownership and competition explains some seemingly inconsistent finding in the literature and points to the complexity of relying on ownership-based policies to protect access in an increasingly competitive health-care system.

Diagnosis-Related Groups↗
PubMed2003

Perspective: repression of competition and the evolution of cooperation.

Repression of competition within groups joins kin selection as the second major force in the history of life shaping the evolution of cooperation. When opportunities for competition against neighbors are limited within groups, individuals can increase their own success only by enhancing the efficiency and productivity of their group. Thus, characters that repress competition within groups promote cooperation and enhance group success. Leigh first expressed this idea in the context of fair meiosis, in which each chromosome has an equal chance of transmission via gametes. Randomized success means that each part of the genome can increase its own success only by enhancing the total number of progeny and thus increasing the success of the group. Alexander used this insight about repression of competition in fair meiosis to develop his theories for the evolution of human sociality. Alexander argued that human social structures spread when they repress competition within groups and promote successful group-against-group competition. Buss introduced a new example with his suggestion that metazoan success depended on repression of competition between cellular lineages. Maynard Smith synthesized different lines of thought on repression of competition. In this paper, I develop simple mathematical models to illustrate the main processes by which repression of competition evolves. With the concepts made clear, I then explain the history of the idea. I finish by summarizing many new developments in this subject and the most promising lines for future study.

Animals↗
PubMed2003

Competition, payers, and hospital quality.

OBJECTIVE: To estimate the effects of competition for both Medicare and HMO patients on the quality decisions of hospitals in Southern California. DATA SOURCE: Secondary discharge data from the Office of Statewide Health Planning and Development for the State of California for the period 1989-1993. STUDY DESIGN: Outcome variables are the risk-adjusted hospital mortality rates for pneumonia (estimated by the authors) and acute myocardial infarction (AMI) (reported by the state of California). Measures of competition are constructed for each hospital and payer type. The competition measures are formulated to mitigate the possibility of endogeneity bias. The relationships between risk-adjusted mortality and the different competition measures are estimated using ordinary least squares. PRINCIPAL FINDINGS: The study finds that an increase in the degree of competition for health maintenance organization (HMO) patients is associated with a decrease in risk-adjusted hospital mortality rates. Conversely, an increase in competition for Medicare enrollees is associated with an increase in risk-adjusted mortality rates for hospitals. CONCLUSIONS: In conjunction with previous research, the estimates indicate that increasing competition for HMO patients appears to reduce prices and save lives and hence appears to improve welfare. However, increases in competition for Medicare appear to reduce quality and may reduce welfare. Increasing competition has little net effect on hospital quality in our sample.

California↗
PubMed2026

Rgg144/SHP144-controlled streptolancidin D mediates intra-species competition in Streptococcus pneumoniae with cumulative effect from other bacteriocins and fratricide.

UNLABELLED: Streptococcus pneumoniae is a major colonizer of the human nasopharynx, where inter- and intra-strain competition plays a critical role in shaping population structure and influencing vaccine outcomes. Bacteriocins are key mediators of intra-species competition, yet many of their functions and regulatory mechanisms remain poorly understood. Here, we identify and characterize streptolancidin D, a previously uncharacterized bacteriocin encoded by the sldA-T locus, and demonstrate its contribution to pneumococcal competition. Using isogenic streptolancidin-producing and non-producing variants of a naturally colonizing strain, we show that sldA-T contributes to the inhibition of competitor strains in in vitro biofilms and during murine co-colonization. Importantly, streptolancidin D also inhibited in vitro a subset of genetically diverse pneumococcal isolates representing multiple serotypes, whereas non-producing variants showed no activity. This indicates that its effect is broad and not restricted to isogenic interactions. Genomic analysis of over 7,500 pneumococcal genomes revealed that sldA-T is present in ~12% of isolates, with lineage-associated distribution patterns, and is consistently encoded downstream of the Rgg144/SHP144 quorum sensing system. We further demonstrate that sldA-T is regulated by this system, with sldA-T promoter activity abolished in a SHP-deficient background and partially restored by exogenous peptide stimulation. Finally, we show that streptolancidin D acts in concert with other bacteriocin systems and competence-mediated fratricide, highlighting a multifactorial antimicrobial strategy that enhances pneumococcal competitiveness. Overall, our findings identify a quorum sensing-regulated bacteriocin that contributes to pneumococcal competition and helps shape population dynamics. IMPORTANCE: Bacteriocins are central to bacterial competition and niche occupation, particularly in structured environments like the human nasopharynx. While several pneumococcal bacteriocins have been characterized, the functions of many remain unknown, limiting our understanding of how these systems shape strain fitness and population dynamics. We characterize streptolancidin D, a bacteriocin that enhances intraspecies competitiveness in vitro and in vivo and contributes to the inhibition of genetically diverse pneumococcal strains. We demonstrate that its expression is tightly regulated by the conserved Rgg144/SHP144 quorum sensing system and that the locus is distributed and shows synteny across multiple pneumococcal lineages. Our findings reveal that streptolancidin D operates within a broader network of bacteriocins and competence-associated mechanisms that collectively shape competitive interactions. By integrating genomic, functional, and regulatory analyses, this work expands the known repertoire of pneumococcal antimicrobial systems and provides new insights into the mechanisms underpinning competition and population structure in S. pneumoniae.

Bacteriocins↗
PubMed2006

Intensity and direction dimensions of competitive state anxiety: a time-to-event approach.

The purpose of the present study was to examine the temporally patterned changes in intensity and direction of competitive state anxiety prior to and during competition as well as correlations among intensity and direction on the Competitive State Anxiety Inventory-2D subscale scores. 99 athletes completed the inventory one day before and an hour before the competition, based on how they felt during that time, and 30 min. after the competition with reference to how they felt during the competition. Analysis indicated different temporal patterning in subscale scores prior to competition. Correlations were medium (.40) for Intensity and Direction dimensions. Significant differences were noted between scores of those classified as Facilitators and Debilitators on the Intensity dimension. The results support the multidimensional nature of competitive anxiety. Moreover, additional information lies in directional interpretation of competitive anxiety and self-confidence.

Adolescent↗
PubMed2005

The evolution of sperm-allocation strategies and the degree of sperm competition.

The prevailing viewpoint in the study of sperm competition is that male sperm-allocation strategies evolve in response to the degree of sperm competition an ejaculate can expect to experience within a given mating. If males cannot assess the degree of sperm competition their ejaculate will face and/or they are unable to facultatively adjust sperm investment in response to perceived levels of competition, high sperm allocation (per mating) is predicted to evolve in the context of high sperm competition. An implicit assumption of the framework used to derive this result is that the degree of sperm competition is unaffected by changes in sperm-allocation strategies. We present theory based on an alternative perspective, in which the degree of sperm competition and the sperm-allocation strategy are coupled traits that coevolve together. Our rationale is that the pattern of sperm allocation in the population will, in part, determine the level of sperm competition by affecting the number of ejaculates per female in the population. In this setting, evolution in sperm-allocation strategies is driven by changes in underlying environmental parameters that influence both the degree of sperm competition and sperm allocation. This change in perspective leads to predictions that are qualitatively different from those of previous theory.

Animals↗
PubMed1988

Genetic analysis of larval competition in Drosophila melanogaster.

A chromosome assay was employed to determine the genetic basis of the competitive ability of the larvae of Drosophila melanogaster when competing for a controlled amount of food. The effects of increasing stress due to intra- and inter-genotypic competition were analysed using a yield-density regression analysis producing estimates of the absolute performance at a standard reference density (e-values), the magnitude of intra-genotypic competition and the inter-genotypic competitive effect of one genotype on another. A distinction was made between the Sensitivity and the Pressure components of inter-genotypic competition. The probability of survival and mean adult weight were used as measures of competitive success. The genetic analysis revealed high levels of heterosis for the e-values and inter-genotypic pressure, with correspondingly high inter-chromosomal interactions. Inter-genotypic sensitivity was less consistently heterotic and less epistatic. All dominance was directed towards a competitively superior genotype and both major autosomes were involved in the determination of competitive ability with the greater effect residing on the third chromosome. There was evidence of early non-competitive larval mortality in one of the two sets of substitution lines investigated and the effect of this on the estimation of the genetic parameters is discussed.

Animals↗
PubMed2002

Sperm competition and the maintenance of polymorphism.

Sperm competition may occur whenever sperm from more than one male are present in the reproductive tract of the female. Studies of field-caught Drosophila reveal that a substantial fraction (80%) of females clearly have sperm from more than one male, and the figure is probably higher because only a small number of progeny are typically surveyed, so a strong skew in paternity can make multiply-mated females appear as singly mated unless appropriate models are applied. Examination of genetic variation in aspects of sperm competition has revealed some striking patterns, particularly in the implications for the maintenance of polymorphism. The magnitude of variation in sperm competitive ability is as great as that for other fitness components, and the males with the strongest displacement also appear to be the ones with the greatest positive effect on fertility. Why then does not the most competitive allele simply go to fixation? Such synergistic pleiotropy makes the polymorphism even more unexpected. Examination of patterns of competitive success of pairs of male genotypes, and of female-male interactions, demonstrate clearly that the outcome of sperm competition is not a simple property of each male. That is, sperm competitive ability of male genotypes cannot simply be ranked from best to worst. Rather, the outcome of each competitive bout depends on the particular pair of males. These results have intriguing implications for the molecular biology of genes involved in the determination of sperm competitive success, and on the opportunity for maintenance of polymorphism in those genes.

Animals↗
PubMed2002

Comparison of competitive-nested PCR and real-time PCR in detecting BCR-ABL fusion transcripts in chronic myeloid leukemia patients.

Real-time RT-PCR has great advantages for estimating transcript levels in a variety of situations. These include relative rapid assay times (hours), reliability and ease of performing replicate analyses. In contrast, competitive PCR is a very labor-intensive procedure requiring a few days to generate useful data. We compared the same samples from CML patients by both methods. Importantly, we used the Bcr-Abl junction plasmid DNA, which is used as a competitor in the manual competitive PCR assay, to generate a standard curve for the real-time assay. This permitted reporting the real-time data as the number of BCR-ABL transcripts per microg of total RNA, which is the same format used for the competitive PCR assay. In this study, a total of 435 peripheral blood and marrow samples from 285 CML patients were analyzed by RT-PCR; these patients were undergoing therapy by STI-571, interferon, and bone marrow transplantation treatment. Most samples also had assay values for the Philadelphia chromosome (Ph), FISH and Western blotting for the Bcr-Abl oncoprotein. Our findings indicated that the real-time assay was less sensitive than the manual competitive RT-PCR assay (t = 5.118; P < 0.001). Of interest, the transcript levels in cell line mixtures with various ratios of K562/KG-1 (BCR-ABL positive/negative) cells were also significantly higher with the competitive RT-PCR assays than real-time RT-PCR, except for levels of BCR-ABL below 200 transcripts per microg of RNA. In both patient and cell line experiments, dividing the BCR-ABL transcripts by the total ABL transcripts virtually eliminated the difference between real-time BCR-ABL transcript values and quantitative competitive BCR-ABL transcript values, indicating that both BCR-ABL and ABL transcripts were underestimated by the real-time assay. In addition, the increased sensitivity of the nested, competitive RT-PCR was readily apparent in patients with minimal residual disease, which by the real-time were negative in the majority of patients but were positive by nested, competitive RT-PCR in 44.6% (n = 29) of samples analyzed (n = 65). These findings indicate that real-time RT-PCR, when normalized for the total ABL transcripts, can be used to monitor CML patients during therapy, but we suggest that nested, competitive RT-PCR be used to determine BCR-ABL/ABL transcript ratios at low transcript values or especially when real-time analyses are negative.

Fusion Proteins, bcr-abl↗
PubMed1996

Significant competitive advantage conferred by meiosis and syngamy in the yeast Saccharomyces cerevisiae.

The presumed advantages of genetic recombinations are difficult to demonstrate directly. To investigate the effects of recombination and background heterozygosity on competitive ability, we have performed serial-transfer competition experiments between isogenic sexual and asexual strains of the yeast Saccharomyces cerevisiae. The members of these diploid pairs of strains differed only in being heterozygous (sexual) or homozygous (asexual) at the mating type or MAT locus. Competing pairs had either a completely homozygous or a heterozygous genetic background, the latter being heterozygous at many different loci throughout the genome. A round of meiotic recombination (automixis) conferred a large and statistically significant enhancement of competitive ability on sexual strains with a heterozygous genetic background. By contrast, in homozygous background competitions, meiosis decreased the sexual strains' initial relative competitive ability. In all cases, however, the sexual strains outcompeted their isogenic asexual counterparts, whether meiotic recombination had occurred or not. In some genetic backgrounds, this was due in part to an overdominance effect on competitive advantage of heterozygosity at the MAT locus. The advantage of the sexual strains also increased significantly during the course of the homozygous background competitions, particularly when meiosis had occurred. This latter effect either did not occur or was very weak in heterozygous background competitions. Overall, sexual strains with heterozygous genetic backgrounds had a significantly higher initial relative competitive ability than those with homozygous backgrounds. The advantage of mating type heterozygosity in this organism extends far beyond the ability to recombine meiotically.

Biological Evolution↗
PubMed2006

The role of immune-mediated apparent competition in genetically diverse malaria infections.

Competitive interactions between coinfecting genotypes of the same pathogen can impose selection on virulence, but the direction of this selection depends on the mechanisms behind the interactions. Here, we investigate how host immune responses contribute to competition between clones in mixed infections of the rodent malaria parasite Plasmodium chabaudi. We studied single and mixed infections of a virulent and an avirulent clone and compared the extent of competition in immunodeficient and immunocompetent mice (nude mice and T cell-reconstituted nude mice, respectively). In immunocompetent mice, the avirulent clone suffered more from competition than did the virulent clone. The competitive suppression of the avirulent clone was alleviated in immunodeficient mice. Moreover, the relative density of the avirulent clone in mixed infections was higher in immunodeficient than in immunocompetent mice. We conclude that immune-mediated interactions contributed to competitive suppression of the avirulent clone, although other mechanisms, presumably competition for resources such as red blood cells, must also be important. Because only the avirulent clone suffered from immune-mediated competition, this mechanism should contribute to selection for increased virulence in mixed infections in this host-parasite system. As far as we are aware, this is the first direct experimental evidence of immune-mediated apparent competition in any host-parasite system.

Animals↗
PubMed2005

Competition for nitrogen between Australian native grasses and the introduced weed Nassella trichotoma.

BACKGROUND: and Aims Nassella trichotoma is an unpalatable perennial grass weed that invades disturbed native grasslands in temperate regions of south-eastern Australia. This experiment investigated whether elevated N levels, often associated with disturbance, increases the competitiveness of N. trichotoma relative to C3 and C4 native Australian grasses. METHODS: A pot experiment investigated competitive interactions between four native grasses, two C3 species (Microlaena stipoides and Austrodanthonia racemosa) and two C4 species (Themeda australis and Bothriochloa macra), and N. trichotoma at three different N levels (equivalent to 0, 60 and 120 kg ha-1) and three competing densities (zero, one and eight neighbouring plants), using an additive design. KEY RESULTS: All native grasses were competitive with N. trichotoma at low N levels, but only M. stipoides was competitive at high N. High densities of native grasses (8:1) had a major competitive effect on N. trichotoma at all N levels. The competitive ranking of native grasses, across all N levels, on N. trichotoma was: M. stipoides>A. racemosa>B. macra>T. australis. The C3 species were generally more competitive than the C4 species and C4 grasses were not inherently more productive at low N levels, in contrast to the results of other studies. CONCLUSION: To resist invasion from N. trichotoma, these native grasses need to be maintained at a high density and/or biomass. The results do not support the theory that species such as N. trichotoma, with high tissues density, are always less competitive than those of low tissue density; in this case competitiveness depended on N levels. The ability of N. trichotoma to accumulate biomass at a higher rate than these native grasses, helps to explain why it is a major weed in disturbed Australian native grasslands.

Australia↗
PubMed1993

Evaluation of a strategy for identifying nodulation competitiveness genes in Rhizobium leguminosarum biovar phaseoli.

Rhizobium leguminosarum biovar phaseoli strain KIM5s is consistently much more competitive than strain CE3 in nodulation of beans (Phaseolus vulgaris L.) in the laboratory and in the field. To identify genes that contribute to the competitiveness of KIM5s, we transferred a cosmid library containing KIM5s DNA into CE3 and applied the transconjugants to bean plants to allow the plants to enrich for those with enhanced nodulation competitiveness. The nodule isolates were then applied to plants for further enrichment. Of 75 isolates from nodules sampled after the two enrichments, 9 were more competitive than CE3. For example, when outnumbered in the inocula 40-fold by a reference strain, these nine strains typically occupied 15-40% of the nodules compared with 0-3% for CE3. However, when these strains were cured of the cosmids, they remained highly competitive, demonstrating that the enhanced competitiveness of the strains was not associated with the cosmids. We found no evidence for cosmid insertion into the chromosome or for cosmid-induced genetic changes in these cured strains. We found some evidence suggesting that their altered competitiveness was due to spontaneous genetic changes that did not involve the cosmids. Although these highly competitive variants remain genetically uncharacterized, they may provide insight into bacterial traits that contribute to, or detract from, successful nodulation competitiveness.

Cosmids↗